Digital Camera Patent Abstract
A digital electronic camera is hermetically sealed in a housing,
typically inexpensive clear plastic. Digital electrical signals
for downloading image information from the camera are converted
to radio or, more preferably, infrared optical signals. These signals
are communicated through the radiation-transparent housing to an
external radio transceiver or infrared adapter connected to a personal
computer. The bi-directional pc-to-camera communication is typically
completely opaque to the picture-capturing pc and to its operating
software. Electrical operation of the digital camera's shutter circuit
is through the sealed housing by manually moving a magnet relative
to an internal sensor, typically a Hall-effect sensor or a reed
switch. Recharging a power source--normally a battery--for the digital
camera and all associated circuitry within the sealed housing transpires
by inductively inducing an alternating current in an coil internal
to the housing, with subsequent rectification and conditioning of
this current. The entire housing may be filled with liquid, preferably
mineral oil or ethyl alcohol, to permit usage of the digital electronic
camera at great depth. Digital Camera Patent Claims
What is claimed is:
1. A waterproof digital electronic camera system comprising: a
digital electronic camera having an RS-232 digital electrical signal
interface for downloading image information from the camera; a converter
converting signals upon the digital electrical signal interface
to serial signals radiating in space; an enclosure hermetically
sealing water and air tight both the digital electronic camera and
the converter, the enclosure being transparent in at least an area
of (i) an optical lens of the digital electronic camera so that
pictures may be taken through the enclosure, and (ii) a radiation
signal output of the converter so that radiation signals containing
image information are communicable exterior to the camera; said
converter comprising: an RS-232 to TTL signal converter converting
RS-232 serial digital electrical signals to Transistor-Transistor
Logic (TTL) serial digital electrical signals; an encoder-decoder
converting the TTL electrical signals to electrical signals that
are suitably encoded so as to be converted to optical signals for
further transmission; and an electrical-to-optical signal converter
converting the encoded electrical signals to optical signals, and
transmitting the optical signals through the at least one transparent
area of the enclosure.
2. A waterproof digital electronic camera system comprising: a
digital electronic camera having a digital electrical signal interface
for downloading image information from the camera; said camera having
a shutter circuit for activating the shutter, to which shutter circuit
electrical connection may suitably be made; a converter converting
signals from the digital electrical signal interface to radiation
signals; an enclosure hermetically sealing water and air tight both
the digital electronic camera and the converter, the enclosure being
transparent in at least an area of (i) an optical lens of the digital
electronic camera so that pictures may be taken through the enclosure,
and (ii) a radiation signal output of the converter so that radiation
signals containing image information are communicable exterior to
the camera; a trigger circuit, also within the enclosure and electrically
connected to the shutter circuit of the digital electronic camera,
responsive to a stimulus external to the enclosure to produce an
electrical signal responsively to which the shutter circuit will
activate the shutter of the digital electronic camera; said trigger
circuit comprising: a Hall-effect sensor responsive to a magnetic
field to produce a signal output; and an amplifier amplifying the
signal output of the Hall-effect sensor for application to the shutter
circuit as the electrical signal responsively to which the shutter
circuit will activate the shutter of the digital electronic camera.
3. A waterproof digital electronic camera system comprising: a
digital electronic camera having a digital electrical signal interface
for downloading image information from the camera; said camera having
a shutter circuit for activating the shutter, to which shutter circuit
electrical connection may suitably be made; a converter converting
signals from the digital electrical signal interface to radiation
signals; an enclosure hermetically sealing water and air tight both
the digital electronic camera and the converter, the enclosure being
transparent in at least an area of (i) an optical lens of the digital
electronic camera so that pictures may be taken through the enclosure,
and (ii) a radiation signal output of the converter so that radiation
signals containing image information are communicable exterior to
the camera; a trigger circuit, also within the enclosure and electrically
connected to the shutter circuit of the digital electronic camera,
responsive to a stimulus external to the enclosure to produce an
electrical signal responsively to which the shutter circuit will
activate the shutter of the digital electronic camera; and said
trigger circuit comprising: a reed switch responsive to a magnetic
field to gate an electrical signal responsively to which the shutter
circuit will activate the shutter of the digital electronic camera.
4. A waterproof digital electronic camera system comprising: a
digital electronic camera having a digital electrical signal interface
for downloading image information from the camera; a converter converting
signals from the digital electrical signal interface to radiation
signals; an enclosure hermetically sealing water and air tight both
the digital electronic camera and the converter, the enclosure being
transparent in at least an area of (i) an optical lens of the digital
electronic camera so that pictures may be taken through the enclosure,
and (ii) a radiation signal output of the converter so that radiation
signals containing image information are communicable exterior to
the camera; a rechargeable power source for providing power to at
least the digital electronic camera and the converter; and a charging
circuit, also within the enclosure, for converting some stimuli
external to the enclosure to power suitable to recharge the rechargeable
power source.
5. The waterproof digital electronic camera system according to
claim 4 wherein the rechargeable power source comprises: a battery.
6. The waterproof digital electronic camera system according to
claim 5 wherein the battery is located within a cavity sealed to
the exterior of the camera by a frangible membrane; wherein the
membrane may be broken, the battery replaced, and the cavity resealed.
7. The waterproof digital electronic camera system according to
claim 4 wherein the charging circuit comprises: an inductive coil
in which alternating current is induced by an oscillatory magnetic
field external to the enclosure; a bridge rectifier rectifying the
alternating current of the inductive coil to produce a direct current;
and a regulating and charging circuit conditioning the direct current
into power to charge the rechargeable power source.
8. A method of communicating with a sealed digital electronic camera
comprising: hermetically housing a digital electronic camera having
an RS232 serial digital electrical signal interface for downloading
image information from the camera in a housing that is optically
transparent in at least an area of a lens of the digital electronic
camera so that pictures may be taken through the housing; converting
signals upon the RS232 serial digital electrical signal interface
of the digital electronic camera to radiation signals by the steps
of: first-converting RS-232 serial digital electrical signals to
Transistor-Transistor Logic (TTL) serial digital electrical signals
in a RS-232 to TTL signal converter; second-converting the TTL electrical
signals to electrical signals that are suitably encoded so as to
be converted to optical signals for further transmission in an encoder-decoder;
and third-converting the encoded electrical signals to optical signals,
and transmitting the optical signals through the enclosure, in an
electrical-to-optical signal converter; and radiatively communicating
the radiation signals through the housing.
9. A method of communicating with a sealed digital electronic camera
comprising: hermetically housing a digital electronic camera having
a digital electrical signal interface for downloading image information
from the camera in a housing that is optically transparent in at
least an area of a lens of the digital electronic camera so that
pictures may be taken through the housing; converting signals upon
the digital electrical signal interface of the digital electronic
camera to radiation signals; radiatively communicating the radiation
signals through the housing; activating a shutter in and by a shutter
circuit to which electrical connection may suitably be made; and
triggering the shutter circuit in and by a trigger circuit, also
within the enclosure and electrically connected to the shutter circuit
of the digital electronic camera, responsive to a stimulus external
to the housing; wherein the triggering of the shutter circuit is
in and by a Hall-effect trigger circuit.
10. A method of communicating with a sealed digital electronic
camera comprising: hermetically housing a digital electronic camera
having a digital electrical signal interface for downloading image
information from the camera in a housing that is optically transparent
in at least an area of a lens of the digital electronic camera so
that pictures may be taken through the housing; converting signals
upon the digital electrical signal interface of the digital electronic
camera to radiation signals; radiatively communicating the radiation
signals through the housing; activating a shutter in and by a shutter
circuit to which electrical connection may suitably be made; and
triggering the shutter circuit in and by a trigger circuit, also
within the enclosure and electrically connected to the shutter circuit
of the digital electronic camera, responsive to a stimulus external
to the housing; wherein the triggering of the shutter circuit is
in and by a reed switch trigger circuit.
11. A method of communicating with a sealed digital electronic
camera comprising: hermetically housing a digital electronic camera
having a digital electrical signal interface for downloading image
information from the camera in a housing that is optically transparent
in at least an area of a lens of the digital electronic camera so
that pictures may be taken through the housing; converting signals
upon the digital electrical signal interface of the digital electronic
camera to radiation signals; radiatively communicating the radiation
signals through the housing; providing power to at least the digital
electronic camera with a rechargeable power source; and converting
some stimulus external to the enclosure into power to recharge the
rechargeable power source.
12. The method according to claim 11 wherein the converting comprises:
inducing an alternating current in an inductive coil inside the
housing; rectifying in a bridge rectifier the alternating current
of the inducing to produce a direct current; and regulating and
conditioning the direct current into power to charge the rechargeable
power source.
13. A digital electronic camera CHARACTERIZED IN THAT: the optics
and electronics of the camera are permanently within a solid mass
of optically clear dielectric material; the camera is potted inside
and out in a solid block of said optically clear dielectric material;
the camera contains essentially no gases whatsoever; and communication
of image data from the camera to the exterior of the solid mass
is via an optical link; wherein the camera may suitably be immersed
to a depth of at least a mile within the ocean without crushing.
14. A digital electronic camera CHARACTERIZED IN THAT: the optics
and electronics of the camera are permanently within a solid mass
of optically clear dielectric material; the camera is potted inside
and out in a solid block of said optically clear dielectric material;
the camera contains essentially no gases whatsoever; and communication
of an actuation signal to a shutter of the camera is via a magnetic
link; wherein the camera may suitably be immersed to a depth of
at least a mile within the ocean without crushing.
15. A digital electronic camera CHARACTERIZED IN THAT: the optics
and electronics of the camera are permanently within a solid mass
of optically clear dielectric material; the camera is potted inside
and out in a solid block of said optically clear dielectric material;
the camera contains essentially no gases whatsoever; and communication
of power to the camera is via inductive coupling; wherein the camera
may suitably be immersed to a depth of at least a mile within the
ocean without crushing.
16. A waterproof digital electronic camera system comprising: a
digital electronic camera having a digital electrical signal interface
for downloading image information from the camera; a converter converting
signals from the digital electrical signal interface to radiation
signals; wherein the converter is converting signals from the digital
electrical signal interface to serial signals radiating in space;
a shutter circuit for activating the shutter, to which shutter circuit
electrical connection may suitably be made; a trigger circuit, also
within the enclosure and electrically connected to the shutter circuit
of the digital electronic camera, responsive to a stimulus external
to the enclosure to produce an electrical signal responsively to
which the shutter circuit will activate the shutter of the digital
electronic camera; a rechargeable power source for providing power
to at least the digital electronic camera and the converter; a charging
circuit, also within the enclosure, for converting some stimuli
external to the enclosure to recharge the rechargeable power source;
and an enclosure hermetically sealing water and air tight both the
digital electronic camera and the converter, the enclosure being
transparent in at least an area of (i) an optical lens of the digital
electronic camera so that pictures may be taken through the enclosure,
and (ii) a radiation signal output of the converter so that radiation
signals containing image information are communicable exterior to
the enclosure.
17. The waterproof digital electronic camera system according to
claim 16 wherein the digital electronic camera has an RS-232 serial
digital electrical signal interface; and wherein the converter is
converting signals from the RS-232 serial digital electrical signal
interface to serial signals radiating in space.
18. The waterproof digital electronic camera system according to
claim 17 wherein the converter comprises: an RS-232 to TTL signal
converter converting RS-232 serial digital electrical signals to
Transistor-Transistor Logic (TTL) serial digital electrical signals;
an encoder-decoder converting the TTL electrical signals to electrical
signals that are suitably encoded so as to be converted to optical
signals for further transmission; and an electrical-to-optical signal
converter converting the encoded electrical signals to optical signals,
and transmitting the optical signals through the at least one transparent
area of the enclosure.
19. The waterproof digital electronic camera system according to
claim 16 wherein the trigger circuit comprises: a Hall-effect sensor
responsive to a magnetic field to produce a signal output; and an
amplifier amplifying the signal output of the Hall-effect sensor
for application to the shutter circuit as the electrical signal
responsively to which the shutter circuit will activate the shutter
of the digital electronic camera.
20. The waterproof digital electronic camera system according to
claim 16 wherein the trigger circuit comprises: a reed switch responsive
to a magnetic field to gate an electrical signal responsively to
which the shutter circuit will activate the shutter of the digital
electronic camera.
21. The waterproof digital electronic camera system according to
claim 16 wherein the rechargeable power source comprises: a battery.
22. The waterproof digital electronic camera system according to
claim 21 wherein the battery is located within a cavity sealed to
the exterior of the camera by a frangible membrane; wherein the
membrane may be broken, the battery replaced, and the cavity resealed.
23. The waterproof digital electronic camera system according to
claim 16 wherein the charging circuit comprises: an inductive coil
in which alternating current is induced by an oscillatory magnetic
field external to the enclosure; a bridge rectifier rectifying the
alternating current of the inductive coil to produce a direct current;
and a regulating and charging circuit conditioning the direct current
into power to charge the rechargeable power source.
24. A method of communicating with a sealed digital electronic
camera comprising: hermetically housing a digital electronic camera
having a digital electrical signal interface for downloading image
information from the camera in a housing that is optically transparent
in at least an area of a lens of the digital electronic camera so
that pictures may be taken through the housing: converting signals
from the digital electrical signal interface of the digital electronic
camera to radiation signals; and radiatively communicating the radiation
signals through the housing: first-converting RS-232 serial digital
electrical signals to Transistor-Transistor Logic (TTL) serial digital
electrical signals in a RS-232 to TTL signal converter; second-converting
the TTL electrical signals to electrical signals that are suitably
encoded so as to be converted to optical signals for further transmission
in an encoder-decoder; third-converting the encoded electrical signals
to optical signals, and transmitting the optical signals through
the enclosure, in an electrical-to-optical signal converter, activating
a shutter in and by a shutter circuit to which electrical connection
may suitably be made; triggering the shutter circuit in and by a
trigger circuit, also within the enclosure and electrically connected
to the shutter circuit of the digital electronic camera, responsive
to a stimulus external to the housing providing power to at least
the digital electronic camera with a rechargeable power source;
converting some stimulus external to the enclosure into power to
recharge the rechargeable power source.
25. The method according to claim 24 wherein the converting comprises:
inducing an alternating current in an inductive coil inside the
housing; rectifying in a bridge rectifier the alternating current
of the inducing to produce a direct current; and regulating and
conditioning the direct current into power to charge the rechargeable
power source.
26. The method according to claim 24 further wherein the triggering
of the shutter circuit is in and by a Hall-effect trigger circuit.
27. The method according to claim 24 further wherein the triggering
of the shutter circuit is in and by a reed switch trigger circuit.
28. A digital electronic camera CHARACTERIZED IN THAT the optics
and electronics of the camera are permanently within a solid mass
of optically clear dielectric material, and the camera contains
essentially no gases whatsoever; wherein the camera may suitably
be immersed to a depth of at least a mile within the ocean without
crushing; wherein the camera is potted inside and out in a solid
block of said optically clear dielectric material; wherein the camera
is within an optically clear liquid dielectric material; wherein
the camera and its liquid are held within a liquid-tight exterior
case that is itself optically clear in at least a region where an
image is received through the case and into a lens of the camera;
wherein image data is communicated from the camera to the exterior
of the solid mass; wherein an actuation signal is communicated to
a shutter of the camera from the exterior of the solid mass; wherein
the power source for the camera is rechargeable; and wherein power
is communicated to the power source from the exterior of the solid
mass.
29. The digital electronic camera according to claim 28 FURTHER
CHARACTERIZED IN THAT said optically clear liquid dielectric material
is ethanol.
30. The digital electronic camera according to claim 28 FURTHER
CHARACTERIZED IN THAT communication of the image data is via an
optical link.
31. The digital electronic camera according to claim 28 FURTHER
CHARACTERIZED IN THAT communication of the actuation signal is via
a magnetic link.
32. The digital electronic camera according to claim 28 FURTHER
CHARACTERIZED IN THAT communication of power to the power source
is via inductive coupling.
Digital Camera Patent Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally concerns digital electronic cameras,
and waterproof housings for cameras including digital electronic
cameras.
The present invention particularly concerns the communication of
(i) information, (ii) control and (iii) power across a watertight
barrier, particularly such as may serve to protect an electronic
instrument, most commonly a digital electronic camera, including
when the instrument is immersed in water.
2. Description of the Prior Art
Relevant Previous Patents
A significant body of prior art concerning waterproof housings
for conventional film cameras is substantially irrelevant to the
present invention for several reasons. First, the housing or case
for a conventional, non-electronic, camera must open for retrieval
and replacement of the film--as will prove to be unnecessary with
a digital electronic camera. Second, since the camera's case or
housing will open, and required replacement of batteries is readily
accomplished by physical substitution, no battery recharging need
transpire through the case or housing.
The case and its waterproof seals can be, and often are, quite
sophisticated in supporting the transmission of mechanical forces
and adjustments as may attend, inter alia, adjustment of the camera's
focus and/or the actuation of its shutter. However, and although
a digital electronic camera may have a focus adjustment and will
have a shutter, these mechanisms can be electrically, as opposed
to mechanically, actuated.
Accordingly, the present invention will prove more analogous to
certain prior art underwater electronic devices--including electronic
imaging devices such as, inter alia, a video tape recorder--than
to underwater film cameras. (Of course, even with a video tape recorder,
a watertight enclosure will open for access to the videotape.)
In this regard, U.S. Pat. No. 3,952,190 to Perkins for an UNDERWATER
STROBE FLASH UNIT concerns a method of waterproofing a strobe flash
unit for use in underwater photography. A mold is formed and a strobe
flash unit is mounted within the mold. Epoxy resin is poured into
the mold to surround the strobe flash unit with the resin. The resin
is then cured until it hardens, at which time the mold is removed
from the epoxy resin and strobe flash unit. The resultant product
is a strobe flash unit encapsulated in a transparent waterproof
casing. Such encapsulation will be seen to be suitably employed
in the present invention.
As regards the communication of power to a hand held underwater
electronic imaging device, U.S. Pat. No. 4,009,419 to Ligman for
a SAFETY CIRCUIT FOR VIDEO DIVER concerns an underwater diver who
is provided with a video camera, light, and communications all of
which is supplied with electrical current from the surface by a
shipboard electrical circuit. The diver is protected from accidental
excessive voltages and current by magnetically isolating the diver's
current from the shipboard current and by employing optical feedback
to control the voltages for the diver. Additionally, a standby battery
is employed to energize this equipment when the shipboard power
fails. The entire shipboard power supply is contained in a waterproof
box upon which is also mounted a video monitor and a video recorder,
both secured in watertight fashion to the box. The present invention
will be seen to involve the transmission of power into a waterproof
enclosure, but not while the enclosure is immersed, and normally
not while an electronic digital camera within the enclosure is in
use.
The present invention will be seen to involve optical data transmission.
U.S. Pat. No. 5,847,753 to Gabello, et al., for a CAMERA SYSTEM
FOR SCANNING A MOVING SURFACE concerns a camera system utilizing
a line scan (linear array) camera designed to scan a moving surface
and subsequently to generate and to transmit a high quality digitized
video signal over a long a distance by an optical fiber. The primary
function of the system is: to scan a moving surface using a 2048
or a 1024 linear array; to condition and digitize the array analog
video signal; and subsequently to transmit to a computer processing
unit, without a noticeable loss in fidelity, the digitized video
data over a long distance by means of an optical fiber connected
to the camera and the computer processing unit. The system also
functions to transmit both video signals and non-video information
signals over a fiber optic link from the camera to the computer
processing unit.
An Exemplary Modification of an Existing Digital Camera
The present invention will be seen to employ but very, very slight--substantially
inconsequential--physical and electrical modifications to an existing
digital electronic camera. No modifications at all are required
by the present invention in the personal computer, nor in the operating
software, that are commonly used to recover digital images from
the digital electronic camera. However, all these things are readily
susceptible of modification, if required.
It is thus useful to consider the susceptibility of a digital electronic
camera to electrical and/or physical modification. An example of
modifications--much more extensive than are required by the present
invention--to an existing digital camera to support of its use in
a non-standard, space borne, environment is shown in a Stanford
University student project.
An Exemplary Existing Digital Electronic Camera
The Logitech Fotoman Plus digital electronic camera is a 8-bit
grayscale digital camera, capable of storing 32 JPEG compressed
pictures in memory. Its specifications, according to Logitech, are
as follows:
The camera dimensions are 16.8 centimeters (6.7 inches) by 8.1
cm (3.2 in) by 3 cm (1.2 in). The camera weight is 284 grams (10
ounces).
Camera image quality is 256 gray levels over 496.times.360 pixels,
for an equivalent resolution of 120 dots per inch (120 dpi) over
a photo approximately 4 in (12.7 cm) wide.times.3 in (8.9 cm) high.
The lens is fixed focus with a 8.5 millimeters (mm) focal length,
f/4.5. The 35 mm camera equivalent focal length is 64 mm. Shooting
range is 3 feet (1 meter) to infinity.
The camera's equivalent film sensitivity is approximately ASA 200
without the neutral density filter, and approximately ASA 25 with
the filter.
The camera's electronic shutter speed is 40 milliseconds (.about.1/30)
with the flash, and 0.5 to 50 msec (1/2000 to 1/20) without the
flash.
The flash guide number equivalent is 27 at ASA 200. The flash shooting
range 3 ft (1 m) to 8 ft (2.5 m). The life of the flash is 10,000
flashes.
The image capacity of camera is 32 pictures in an image storage
medium: namely, solid state (dram) memory with battery backup.
The image sensor type is a CCD (charge-coupled device). The raw
image size is 179 kb (8 bits per pixel). Compressed image size varies
with the image. Average compressed image size is 23 kb with 8:1
compression using the JPEG image compression method.
The adapter rings have a small end of 27 mm threaded outer diameter,
and a large end of 37 mm threaded inner diameter.
The camera cable length is 6 ft. (2 m) of cable suitable for the
camera's RS423 serial interface (which is simply +/- 5v version
of the more famous RS232 serial interface, which will be seen to
be the type used in the preferred embodiment of the present invention).
The baud rate of the interface is 9.6 K baud receive, and 9.6K,
19.2K, 38.4K, 57.6K, of 115k baud transmit.
The main power source of the camera is two rechargeable nickel-cadmium
batteries, AA size, 600 ma, 1.2 V. The time needed to charge these
Ni-Cad batteries is 6 hours minimum. In estimating loss of charge
in the Ni-Cad batteries assume that, at room temperature, the batteries
lose about 20% of a full charge every time the camera takes one
full load of photos (32 photos). The batteries lose about 15% of
a full charge every time the camera goes 24 hours without recharging.
The battery charger has an output 12 vdc +4 v, -2 v, 500 mah minimum.
The polarity-positive pole is at center.
A memory power source is based on a 3 v lithium cell.
Camera operating temperature and humidity is 0 to 40.degree. C.
at 95% humidity or less. Camera storage temperature and humidity
is -40 to 50.degree. C. at 95% humidity or less.
An existing Logitech Fotoman Plus digital camera (the "Fotoman
camera") is modified by, among other things, placing it in
a protective box. The capabilities of this digital camera include
JPEG image compression, storage in DRAM of up to 32 496.times.360
images with 8-bit gray scale in compressed form. The compression
results in a JPEG image size of about 23 Kb.
A serial link to the CPU, RS-232, is used to load into the Fotoman
camera memory its operating software, to give it instructions, and
to transfer back the camera status and full images.
The digital camera can be powered on/off, from the +5 V bus of
the spacecraft. A voltage regulator and a bypass capacitor are used
to replace the Ni-Cad batteries normally used to power the Fotoman
Plus (see schematic) A lithium battery, used by the Fotoman to maintain
the operating software in memory, is left in the camera.
2.2.2 Exemplary Previous Electrical Modifications to an Existing
Digital Electronic Camera
In accordance with the present invention, connection will be made
to the circuitry of a digital electronic camera. That a connection
to--and more, rising to the level of actual modification of--the
circuitry of an existing digital electronic camera might be made
is known.
For example, the aforementioned Fotoman Plus digital electronic
camera was subjected to electronic modifications. The Fotoman Plus
camera was already designed with appropriate digital communications
interfaces without the need for any custom adapter. However, an
external switch controlled by the on/off command from the CPU and
voltage regulation had to be added. It was so added by wiring an
existing RS423 serial interface from a bottom 6 electrodes already
present in the camera. (With the lens on top, the six electrodes
from left to right are: 1. Connection directly to the battery through
a fuse, located in the camera, which is used to monitor battery
level in manufacturing. A battery eliminator could be connected,
but the fuse would have to be bypassed; 2. RS423 out; 3. Charge
in (+12 V); 4. RS423 in; 5. Ground, used for both power and RS423;
and 6. Unused.)
Next, a power regulation and switching circuit were designed to
turn on the Fotoman camera if a "on" signal was received
from the CPU through the bus of the space satellite in which the
modified camera was to be flown, and contained.
Finally, the flash had to be selectively electronically disabled
by removing certain components off the PCB. (The components were
C32, Q18, Q24, Q27, R94, and R93, as indicated on the printed circuit
board of the camera.)
2.2.3 Exemplary Modifications to the Software-Based Interface and
Control of an Existing Digital Electronic Camera
It will be seen to be one of the strengths of the present invention
that no modification is needed to the firmware within the camera,
nor the software within a connecting computer. It will be understood,
however, that such minor modifications as might be required are
well within the skills of a practitioner of the digital computer
programming arts.
For example, the Fotoman Plus camera has a command set the detail
nature of which is not of particular concern in the present application.
Using this instruction set software for control of the camera was
modified in accordance with the space mission of the camera.
The Fotoman Plus camera software architecture is based on a boot
code stored in the Fotoman Plus camera ROM. This main code stored
in the Fotoman Plus camera RAM is known as FOTOWARE. This code operates
the Fotoman Plus camera, performs the data compression, and manages
the communications with an external computer through a serial link.
The Fotoman Plus camera software architecture is also based on
an exploitation code, known as FOTOTOUCH, based on an external computer.
This code contains a dialogue/acquisition segment, an executable
named FOTOMAN.EXE, and an image processing segment.
Finally, the Fotoman Plus camera software architecture is also
based a native mode communication program TERM permitting ASCII
commands--used in commanding the Fotoman Plus camera--to be entered
via a keyboard.
The camera modification plan called for a special version of the
FOTOWARE that permitted programmed (i) disabling of the flash, (ii)
manual setting of the exposure time, and (iii) control of the battery
counter. The battery counter is a model of the battery maintained
by the FOTOWARE, which does not measure any physical quantity from
the batteries. However, the battery counter must be above a certain
level, before the Fotoman can take a picture.
However, if the camera batteries are removed and replaced, the
on=board software assumes that the replacement batteries are uncharged.
As the power circuitry for the digital camera replaces the batteries,
on power up, the counter will read zero and the camera will not
be able to take a picture. By controlling the counter, the programmer(s)
can change the erroneous indication of insufficient power, and can
take a picture immediately. Flash control is recommended, as the
flash will be physically disabled.
FOTOTOUCH or any other standard image manipulation package can
be used in the ground station to view and process the images, which
are downloaded in standard JPEG format.
2.2.4 Exemplary Use of a Modified Existing Digital Electronic Camera
The present invention deals with a digital electronic camera modified
for underwater use. It is known to attempt to modify a digital electronic
camera for a specific applications environment, to wit: the space
borne application of the Fotoman Plus camera.
In that application full new software supports camera dialogue/acquisition
with the spacecraft CPU, and interfaces the camera into the main
control module of the spacecraft. This software performs the following
tasks: 1. turning on and off the Fotoman Plus; 2. uploading FOTOWARE
from the PROM into the Fotoman Plus RAM at a given time; 3. sending
orders to take pictures to the Fotoman; 4. Request and receiving
status, contact, and image inventory information; and 5. retrieving
pictures from the Fotoman, to be stored in the CPU, which will be
sent at a later time to the ground station.
These tasks can be performed using the 16 commands set of provided
in the Native Mode Toolkit.
Typical tasks for the modified FotoMan executable under software
control are to 1. take a picture at a given time (using the on-board
clock); and 2. download a picture #n stored in CPU memory.
For further explanation see the Fotoman Plus camera User's Guide
(a basic user's guide) and the Fotoman Plus Camera Native Mode Toolkit
(logical interface specifications) supplied by Logitech Inc., Fremont
Calif. 94555. See also JPEG documentation and source code at ftp
site: ftp.uu.net /graphics/jpeg file jpegsrc.v4.tar.Z; and general
information on image compression from the list at FAQ of the Internet
newsgroup at comp.compression.research.
SUMMARY OF THE INVENTION
The present invention contemplates a weathertight and watertight
digital electronic device, particularly a digital camera, that is
designed to operate both on land and underwater to great depths.
The camera is preferably hermetically sealed, and is thus impervious
to contamination both from the atmosphere--such as may arise from
wind-blown sand and smoke--and from water and like fluids, including
during full immersion including at great depths and pressures.
The hermetic sealing is realized by an encapsulating housing, or
case. This housing is totally without any passage of (i) electrical
wires or cables conducting electrical current, or of (ii) mechanical
plungers or actuators imparting mechanical force(s), through its
wall(s). Thus when the housing is described as "hermetically
sealed" in this specification then this term means more than
"airtight", but, as will be seen, less than "immune
to external influence"--as are both dictionary definitions
of the word "hermetic". The concept of "hermetic
sealing" of a digital electronic device, or camera, in accordance
with the present invention is this: there are no seals, nor any
points of substantially different vulnerability to breach, within
the entire housing. Indeed, the housing may be molded as a monolithic
block. Its surface may be fashioned--at least so far as regards
possibilities and potential for ingress or egress to the digital
camera or other electronic device contained inside--as a continuum,
meaning by dictionary definition something of which no distinction
of content may be affirmed except by reference to something else.
In simplest terms, once sealed shut the housing is solid, and like
as a monolith without any physical passages whatsoever within its
surface.
Nonetheless that the watertight digital electronic camera of the
present invention is hermetically sealed--or possibly because it
is so hermetically sealed--its housing, and all necessary electrical
and digital electrical communication with the camera, are economical
to manufacture. This economy results primarily because, as explained
above, there are absolutely no physical passages though the housing
of the camera, nor are any expensive waterproof fittings employed.
Indeed, in one of its embodiments the housing of the camera is formed
by completely encapsulating the camera, and some modest auxiliary
electronics, within a solid block of, preferably, plastic during
a potting process.
The hermetically sealed watertight digital electronic camera so
constructed is characterized by having all necessary (i) signal,
(ii) control and (iii) power communication with the camera transpire
by and through radiation links that pass through the housing of
the camera.
Regarding (i) signal communication, the communication of image
data from the camera to the exterior of its transparent case is
preferably via a radio or, more preferably, an optical link, most
preferably an infrared optical link.
Regarding (ii) control communication, the watertight digital electronic
camera so constructed is further characterized in that communication
of an actuation signal to the shutter of the camera preferably transpires
via a magnetic link. In the preferred embodiment a trigger circuit
based on a Hall-effect sensor or a reed switch, and located interior
to the sealed case, produces an electrical signal suitable to actuate
the camera's existing shutter circuit whenever a small permanent
magnet exterior to the case is brought into proximity, normally
by manual movement in a simple sliding mechanism in a manner suggestive
of a standard shutter release.
Regarding (iii) power communication, the watertight digital electronic
camera so constructed is still further characterized in that the
camera has, quite conventionally, a rechargeable source of power,
normally a battery. This power source is, however, quite unconventionally
recharged via an inductive coupling. In the preferred embodiment
of the camera an oscillating, alternating current (a.c.), electromagnetic
field external to the camera housing is inductively coupled into
(i) an inductive coil internal to the housing. Also internal to
the housing, (ii) a bridge rectifier rectifies the alternating current
induced in the inductive coil to produce a direct current, and (iii)
a regulating and charging circuit conditions this direct current
into power to charge the rechargeable power source.
As a still further major aspect of the present invention, the housing--which
is normally formed quite snug to the camera and its auxiliary electronic
circuits--may be filled with an optically-transparent electrically-dielectric
liquid. The housing may even be formed by potting: solidifying a
liquid polymer that extends into all regions and volumes of the
housing--including inside the camera proper--into a solid block
of optically-transparent electrically-dielectric plastic. This construction,
which leaves the enclosed volume of the housing substantially entirely
devoid of gas, permits that the waterproof camera may be used at
great depths of at least a mile, and may be non-destructively subjected
to correspondingly great hydrostatic pressures. Any necessary preset
to the lens system of the camera to account for the differing indexes
of refraction of air and of the potting plastic is contemplated.
1. An Underwater Digital Electronic Camera System
Therefore, in one of its aspects the present invention will be
recognized to be embodied in a waterproof digital electronic camera
system suitable for use underwater. The system includes (i) a digital
electronic camera, and (ii) a converter, in (iii) an enclosure.
The (i) digital electronic camera has a digital electrical signal
interface for downloading image information from the camera.
The (ii) converter converts signals upon the digital electrical
signal interface to optical or to radio frequency signals.
The (iii) enclosure hermetically seals water and air tight both
(i) the digital electronic camera and (ii) the converter. The enclosure
is transparent in at least an area of lens of the digital electronic
camera so that pictures may be taken through the enclosure. The
enclosure is additionally transparent to radiation so that either
an optical, or a radio frequency, signal output of the converter--which
signal contains image information --is communicable exterior to
the camera.
The (i) digital electronic camera typically has a serial digital
electrical signal interface, and most commonly an RS-232 interface,
thus making that (ii) the converter is converting signals upon this
serial digital electrical signal interface to serial optical, or
radio frequency, signals. The preferred converter in particular
includes (a) an RS-232 to TTL signal converter converting RS-232
serial digital electrical signals to Transistor-Transistor Logic
(TTL) serial digital electrical signals, and (b) an encoder-decoder
converting the TTL electrical signals to electrical signals that
are suitably encoded so as to be converted to optical or radio frequency
signals for further transmission. The converter further has (c)
an electrical-to-optical, or an electrical-to-radio, signal converter
for converting the encoded electrical signals to optical or radio
signals, and for transmitting the optical or radio signals through
the at least one radiation-transparent area of the enclosure.
Conversion need not be realized in a converter having these exact
functional or physical sections (a)-(c). For example, in one embodiment
of the invention an RS-232(C) electrical signal to and from the
camera goes directly to a (spread-spectrum) radio frequency transceiver
module for bi-directional communication outside the camera. Moreover,
in many embodiments of the camera system some or all of these three
sections (a)-(c) of the converter may be hard to locate, and distinctly
identify. For example, all three sections (a)-(c) may be combined
in an optical, or in a radio, transceiver. It will be recognized
by a practitioner of the electromagnetic communication arts that
there are diverse ways of communicating electrical signals upon
an electronic device, particularly a digital electronic camera,
bi-directionally through a radiation-transparent window located
in a case encapsulating the device (the camera).
Further in the preferred system of the invention, the digital electronic
camera conventionally has a shutter circuit for activating the shutter,
to which shutter circuit electrical connection may suitably be made.
Meanwhile, the overall system additionally includes a trigger circuit.
This trigger circuit is within the enclosure and is electrically
connected to the shutter circuit of the digital electronic camera.
It serves to respond to some stimulus external to the enclosure
so as to produce responsively thereto an electrical signal which,
as and when supplied to the shutter circuit, will activate the shutter
of the digital electronic camera.
The trigger circuit may be implemented in several different variants.
A Hall-effect sensor responsive to a magnetic field can be used
to produce a signal output, with an amplifier amplifying this signal
output for application to the shutter circuit as the electrical
signal responsively to which the shutter circuit will activate the
shutter of the digital electronic camera. Triggering of the Hall-effect
sensor may be realized by the simple expedient of manually moving
a permanent magnet, external to the enclosure, into physical proximity
to the Hall-effect sensor that is within the enclosure.
Alternatively, the trigger circuit may be based on a reed switch,
or sensor, that is also responsive to a magnetic field to gate an
electrical signal responsively to which the shutter circuit will
activate the shutter of the digital electronic camera.
Still further in the preferred system of the invention, the digital
electronic camera has, as is again conventional, a rechargeable
power source, normally a battery, for providing power to at least
the digital electronic camera and also, in the case of the system
of the invention, the converter. In this eventuality the overall
system preferably further includes a charging circuit, also within
the enclosure, for converting some stimulus external to the enclosure
to power suitable to recharge the rechargeable power source. The
stimulus is preferably an oscillating, alternating current (a.c.),
electromagnetic field. Accordingly, the preferred charging circuit
includes (i) an inductive coil in which alternating current is induced
by an oscillatory magnetic field external to the enclosure, (ii)
a bridge rectifier rectifying the alternating current of the inductive
coil to produce a direct current, and (iii) a regulating and charging
circuit conditioning the direct current into power to charge the
rechargeable power source.
The enclosure of the digital electronic camera and its associated
auxiliary electronics is structurally simple and inexpensive, but
functionally sophisticated. In one preferred variant the camera
and the converter (and any other incorporated features such as the
trigger circuit and/or the charging circuit) are entirely potted
in an optically clear dielectric material. This optically clear
dielectric potting material is preferably drawn from the group consisting
essentially of plastic and any of hydrocarbon liquids, mineral oil,
polyester resin and clear silicone rubber. The optically clear dielectric
potting material is more preferably polycarbonate plastic and ethyl
alcohol.
In a first variant of this potting, discussed further in section
3, below, the potting may extend into the interior volumes of the
camera (and anything else, such as the inductive coil), so that,
ultimately, the enclosure contains only solid masses, and is devoid
of any gas whatsoever.
In another, second, variant the (potted, or otherwise sealed) enclosure
contains both solid and liquid masses, only, and there is still
essentially no gas whatsoever within the enclosure nor within the
camera that is within the enclosure. In this variant the liquid
is an optically clear dielectric, and thus interferes with neither
the optical functions of the camera nor the electrical functions
of the camera and of the converter.
In yet another, third, variant the (potted, or otherwise sealed)
enclosure may contain solid and/or liquid masses, but with a slight
remaining volume between the elements of a compound lens, and/or
between the lens and the (clear) camera case, in which is captured
gas, normally air. This third variant camera may be quite easily
constructed, typically requiring no alteration, even to the modest
extent of de-focusing, of the optical system of the (digital electronic)
camera. To such extent as the "gas pocket" is well protected,
the camera may function at considerable pressures, and depths ranging
to, typically, hundreds of feet. However, at the very greatest depths
of the ocean, the gas pocket represents a compressible fluid, and
its presence may undesirably physically distort the remaining structure
of the encapsulated camera even if it does not lead to failure by
rupture.
2. An Encapsulated Waterproof Digital Electronic Camera System
Therefore, in another of its aspects the present invention will
be recognized to be embodied in a waterproof digital electronic
camera where the optics and electronics of the camera are permanently
within a solid mass of optically clear dielectric material, and
where the camera contains essentially no gases whatsoever. By this
construction the camera may suitably be immersed to great depth
within the ocean without crushing.
In one variant of construction the digital electronic camera is
potted inside and out to be within a solid block of optically clear
dielectric material, preferably plastic and more preferably polycarbonate
plastic.
In another variant of construction the digital electronic camera
is within an optically clear liquid dielectric material, the camera
and its liquid being held within a liquid-tight exterior case that
is itself optically clear in at least a region where an image is
received through the case and into a lens of the camera. The preferred
liquid is a liquid hydrocarbon, and is more preferably ethanol.
3. An Underwater Watch
As a further extension of the broad concepts of the present invention
a completely sealed underwater watch can be made by encasing a digital
watch, including its electronics and battery, inside a clear plastic
slab. The settings of the watch can be changed using the hall-effect
magnetic proximity switches described above. The watch battery can
also be recharged as previously described for the waterproof digital
electronic camera.
Alternatively, the watch can simply be fitted with a single battery
which will last for several years; the nominal life of the watch.
(An optional photovoltaic array permits recharging.) The watch is
economical yet operable at great depths and pressures since it is
entirely embedded in plastic and there are no, or substantially
no, air spaces inside.
These and other aspects and attributes of the present invention
will become increasingly clear upon reference to the following drawings
and accompanying specification.
BRIEF DESCRIPTION OF THE DRAWINGS
Referring particularly to the drawings for the purpose of illustration
only and not to limit the scope of the invention in any way, these
illustrations follow:
FIG. 1 is a cross-sectional top plan view of an air-filled first
preferred embodiment of a waterproof digital electronic camera system
according to the present invention, this first embodiment communicating
digital information via an optical link.
FIG. 2 is a combination electrical and mechanical detail schematic
diagram of the preferred embodiment of a waterproof digital electronic
camera system according to the present invention, previously seen
in FIG. 1, particularly showing a preferred shutter actuation interface.
FIG. 3 is a combination electrical and mechanical schematic diagram
of a preferred embodiment of a waterproof digital electronic camera
system according to the present invention, previously seen in FIGS.
1 and 2, particularly showing a preferred optical-link data interface.
FIG. 4 is a combination electrical and mechanical detail schematic
diagram of the preferred embodiment of a waterproof digital electronic
camera system according to the present invention, previously seen
in FIGS. 1 through 3, particularly showing a preferred power switch
interface.
FIG. 5 is a combination electrical and mechanical detail schematic
diagram of the preferred embodiment of a waterproof digital electronic
camera system according to the present invention, previously seen
in FIGS. 1 through 4, particularly showing a preferred recharging
interface.
FIG. 6 is a combination electrical and mechanical detail schematic
diagram of the preferred embodiment of a waterproof digital electronic
camera system according to the present invention, previously seen
in FIGS. 1 through 5, particularly showing a first variant of the
construction of a transformer within the preferred recharging interface
previously seen in FIG. 5.
FIG. 7 is a combination electrical and mechanical detail schematic
diagram of the preferred embodiment of a waterproof digital electronic
camera system according to the present invention, previously seen
in FIGS. 1 through 5, particularly showing a second variant of the
construction of the transformer of the preferred recharging interface
previously seen in FIG. 5.
FIG. 8 is a cross-sectional top plan view, similar to FIG. 1, of
an air-filled variant preferred embodiment of a waterproof digital
electronic camera system according to the present invention, this
variant embodiment communicating digital information via a radio
link.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Although specific embodiments of the invention will now be described
with reference to the drawings, it should be understood that such
embodiments are by way of example only and are merely illustrative
of but a small number of the many possible specific embodiments
to which the principles of the invention may be applied. Various
changes and modifications obvious to one skilled in the art to which
the invention pertains are deemed to be within the spirit, scope
and contemplation of the invention as further defined in the appended
claims.
The present invention is embodied in an underwater electronic digital
camera which never needs to be opened except perhaps, optionally,
for replacement of a rechargeable battery. Even this apparent limitation
to, and difficultly in, preserving the watertight integrity of the
camera has a solution which will be described below.
1. The Housing
A cross-sectional top plan view of a first, air-filled, preferred
embodiment of a waterproof digital electronic camera system 1 according
to the present invention is shown in FIG. 1. An entire digital electronic
camera 11, including its optics 111, are contained within a waterproof
case, or housing, 12. The digital camera 11 is preferably Kodak
type DC 210: an electronic digital zoom camera.
The housing 12 is preferably constructed of two plastic encasings
121 and 122, one fitting inside the other. The smaller inner encasing
121 is fitted over the camera 11 and its optics 111, forming a compartment
13. This compartment 13 is filled with air in a first variant embodiment
of the camera system 1 and its housing 12, and with fluid or solid,
polymerized, plastic in a second variant embodiment of the camera
system 1 and its housing 12.
(1) Control wires 14 and (2) power wires 151, 152 connect the camera
11 through holes in the inner housing 121 respectively to (1) switches
161-163 and infrared (IR) PC interface link 17, (2) the power switch
181, and (iii) the battery 184 (itself connected to recharging circuit
183 and charging coil 182). Clear plastic resin is poured into the
space interior to the outer housing 122 but exterior to the inner
housing 121. This forms an economical yet hermetic housing capable
of withstanding high underwater pressures at great depths.
A mass-produced version may be fabricated as a single casting of
polycarbonate or Lucite.TM. plastic (Lucite is a trademark of Rohm
& Haas, Inc.). The inner air compartment then consists of a
thin-walled clear plastic box 121 embedded in a solid potting, or
casting, which holds the optics 111 of the camera 11 aligned in
the air compartment until the plastic cures.
2. The Switches
Switches 161-163, 181 in the form of reed proximity switches or
Hall-effect devices are placed near the outer wall of the outer
housing 122. To the outside of the housing 122, small rubber beads
191-194, each with an associated magnet 201-204 mounted on its outer
surface, are placed near each proximity switch 161-163, 181. By
depressing the rubber beads 191-194 with the fingers the associated
magnets 201-204 are brought closer to the associated switch, activating
the switches 161-163, 181. As may later best be understood by reference
to the partial schematics of FIGS. 3-5, this magnetic switching
may alternatively be accomplished by Hall Effect semiconductor switches
(at least in the locations of switches 161-163)--which also results
in a more sensitive switch design.
Hall-effect semiconductors also have the advantage of no moving
parts without any requirement for such gas space--required by the
reed switches--as may hinder use of the camera at great depth and
pressure. However, for the gating of main power (see the pictorial
partial schematic of FIG. 4) a reed switch is superior since there
will not be any leakage current. The main power switch 181 may be
fashioned unlike the other switches 161-163 in that a latching mechanism
must be provided. A simple sliding element as is diagrammatically
illustrated in FIG. 4, or, alternatively, a sideswipe lever (not
shown), entirely fabricated from plastic can work to selectively
emplace a magnet, normally embedded inside the manually slidable
or otherwise movable part, into proximity with, or separation from,
the switch 181.
However, for certain digital electronic cameras suitable for use
in the present invention, such as the Kodak DC210, even the power
switch is momentary in operation. Therefore all switches may suitably
be implemented as Hall switches.
A preferred variant of any of the switches 161-163 (shown in FIG.
1) is shown in detail in the combination electrical and mechanical
schematic block diagram of FIG. 2.
The first variant preferred shutter actuation interface includes
a magnet 204 mounted on slide switch 1611 having a sliding lever
1613 and retained in the illustrated position by elastic bands,
or plastic springs, 1612. Pressing with the fingers on the lever
1613 in the direction of vector A moves the side switch into the
stop 1614, positioning magnet 204 proximate to Hall effect sensor
1615 and producing an electrical signal which, as amplified in amplifier
1616, suffices to trigger the shutter of the camera 11 (not shown
in FIG. 2; shown in FIG. 1) electrically connected to wire 1617.
The Hall effect sensor 1615 is preferably Micronics type HAL 1145VA.
The amplifier 1616 is preferably industry standard part number 7400.
The switch 181, which controls the application of power from the
battery 184 to the camera 11, will be more particularly discussed
in following section 4.
3. The Data Interface
The data interface of the waterproof digital electronic camera
system of the present invention, and more preferably an infrared
serial personal computer interface including the infrared (IR) PC
interface link 17 shown in FIG. 1, is illustrated in the combined
schematic and diagram of FIG. 3.
The preferred PC interface takes place through an infrared (IR)
PC interface link 17 consisting of an RS-232C to TTL converter 171,
an encoder-decoder 172 and an infrared IrDa compliant transceiver
173. The RS-232C to TTL converter 171, an industry standard part,
receives serial data in the RS-232C interface format upon two 115,200
bit per second (bps) signal lines 174 from the digital electronic
camera 11.
Then encoder-decoder 172 is preferably Hewlett-Packard type HSDL-7001.
The infrared IrDa compliant transceiver is preferably Hewlett-Packard
type USDL-1001. Together these components transmit the data received
from the digital electronic camera 11 upon a digital optical, and
more particularly an IrDA-compliant infrared, link.
These infrared pulses are detected by an IrDA adapter 3 to a personal
computer (PC) 4. The preferred IrDA adapter 3 is the "Jeteye
IrDA adapter" available from Extended Systems, Inc. This component
converts the received infrared pulses back into an electrical RS-232C,
other standard, interface format.
Accordingly, in the present invention electrical data signals from
the digital electronic camera 11 are translated into optical pulses
in the IR spectrum and passed through the transparent wall of the
camera's housing 12 to an integrated IR detector and signal converter,
or IrDa Adapter 3, on the other side. The IR interface can easily
handle the bandwidth required for data transmission in accordance
with the RS-232C interface standard, even at high baud rates. The
entire process is opaque to both (i) the digital electronic camera
11 and the firmware operating therein, and to (ii) the PC 4 and
the software operating therein.
4. The Power Switch
The preferred power actuation interface shown in FIG. 4 again uses
a magnet 204, now mounted on toggle switch 1811 having a swing arm
1812 retained in the illustrated position by a latch 1813. Moving,
under force of the fingers, the magnet 204 proximate to the Reed
relay switch 181 closes this reed switch 1814, gating power through
the path thereby established from the battery 184 to the camera
11 (both shown in FIG. 1).
4. The Recharging Interface
A charging coil 182, preferably with a ferrite core (as will be
more particularly illustrated in FIGS. 6 and 7) is located inside
the plastic outer housing 122. This charging coil connects to a
charging circuit 183 and through this circuit to a battery 184.
When the battery is to be recharged, another coil carrying an alternating
current (not shown in FIG. 1, shown in FIGS. 6 and 7) is placed
outside the other housing 121 proximately to the charging coil 182,
and is aligned to induce current in this internal charging coil
182. The outer coil acts as the primary winding of a transformer
while the inner, charging, coil 182 acts as the secondary. The alternating
current inductively induced in the inner (secondary) charging coil
182 is then rectified, filtered and regulated in the charging circuit
183 and applied as a d.c. current to charge the battery 184. In
this way the battery 184 can be charged without any need for opening
the housing 122, or even for having any wires to penetrate the housing
122. The battery 184 is charged and recharged entirely while it
is continuously within the plastic housing 122.
The battery 184 may be located behind a frangible barrier, or membrane
(not shown in isolation, but within the surface of the case 12).
This barrier may be broken, pried open or the like, and the battery
replaced. Then the barrier, or a substitute replacement barrier,
is replaced, normally by use of adhesive, so as to again render
the battery 184 and the interior of the case 12 again gas-tight.
A detail combination electrical and mechanical schematic block
diagram of the preferred embodiment of the recharging circuitry
for the waterproof digital electronic camera system according to
the present invention, previously seen in FIGS. 1 through 4, is
shown in FIG. 5. An external source of a.c. power 5 is inductively
coupled through transformer 18, the secondary winding of which is
the charging coil 182 located inside the housing 12 (shown in FIG.
1). The a.c. current induced in the charging coil 182 (a transformer
winding) is communicated to rectifier 1831, normally a simple diode
bridge, and filtered as a d.c. voltage in capacitor 1832. The d.c.
voltage and current is conditioned in battery charging circuit 1833
and applied to charge battery 184. Power from the battery 184 may
optionally be regulated in voltage regulator 1834 before application
to camera 11 (shown in FIG. 1).
These same components of FIG. 5, now in conjunction with a first,
and a second, variant embodiments of the transformer 18, are respectively
illustrated in FIGS. 6 and 7. The physical design of the transformer
18a of FIG. 6 realizes good inductive coupling between the primary
and secondary coils of the transformer because the primary coil
is (in terms of the flow of magnetic flux) located across the secondary
coil. The transformer 18 configuration requires that the charger
for the camera--which is, of course, normally used only when the
camera is not in use for imaging--have a greater thickness than
does the camera, which some users may find objectionable. Although
the primary coil is still, in terms of the flow of magnetic flux,
located across the secondary coil in the variant embodiment of FIG.
7, the primary and secondary windings of the transformer 18 are
of equal thickness, and the charger for the camera 11 may be as
thin as is the camera itself.
5. A Solidly Encapsulated Embodiment
An alternative second embodiment of the hermetically sealed digital
electronic camera in accordance with the present invention is essentially
the same as the first embodiment with one important difference:
the entire camera including both the camera electronic and optics
are cast into clear casing resin or other clear plastic.
The optics are normally constrained to be immovable, and thus focus
free. These focus free optics may be preset, or, in extreme cases,
custom designed by aid of standard ray-tracing lens design programs
that accord consideration to the indices of refraction of all media
in the optical path, so as to correctly accommodate the index of
refraction of the clear plastic medium which is, of course, different
than that of air.
This solidly encapsulated design offers the advantage of easy manufacture
while permitting camera operation to virtually any depth under water
because, with virtually no airspace within the camera, there is
no pressure differential between the outside and the inside of the
camera. Like the more rudimentary hermetic sealing of the camera
with some gas still inside, the second embodiment is enabled by
the fact that the camera never needs to be opened during all phases
of operation.
5.1 A Fluid-Filled Housing Variation on the Second Embodiment
A variation on the second embodiment of the invention employs a
housing that is fluid-filled, or that is at least in part fluid
filled. The preferred fluids are clear dielectrics. Both common
mineral oil and synthetic gel suffice. However, if the fluid is
present in the optical path, fluids with high optical transmissivity
are preferred. These fluids are associated with fluid-filled optical
light pipes, and may readily be located in, inter alia, the patent
literature on this precise subject.
Note that certain fluids transmit better in certain regions of
the optical spectrum. Clearly any fluid in the optical path of the
digital camera should be chosen in consideration of the frequency
of the images desired to be registered by the camera. For example,
the electronic sensor array plane of the camera need not be a Charge
Coupled Device (CCD) targeted on visible light, but may instead
be an active pixel array sensitive, in the manner of the common
use of these arrays in telescopes, to infrared light. Clearly if
the digital electronic camera is to capture images in infrared light,
any liquid (or solid) in the optical path would be highly transparent
to light of this frequency.
The housing is closed around the fluid or gel, and experiences
zero pressure differential. Yet the camera electronics are protected.
This variant embodiment has the advantage that housing could be
opened and the camera electronics removed for servicing. Also, in
the event that the camera optics must move, such as to focus, the
fluid or gel can accommodate this.
6. Optional Replacement of the Rechargeable Battery
Any replacement of the rechargeable battery which may at some point
become necessary may, in accordance with the present invention,
optionally be made possible by having a battery compartment located
near the outside of the housing. The battery is installed in a suitable
battery holder and then this sub-compartment is filled with, preferably,
a soft-casting plastic (a silicone seal or similar) which provides
a hermetic seal around the battery and all wires and contacts. When
the battery is to be replaced, the soft silicone is cut away with
a small knife and the battery replaced. Upon replacement of the
battery, the battery compartment is then refilled--normally as tightly
as is possible --and is, at a minimum, capped over with soft silicone
rubber.
7. Gas-filled, and Solid- or Liquid-Filled, Embodiments of the
Underwater Electronic Digital Camera
In one embodiment of an underwater camera in accordance with the
present invention, the optics of the camera, or the entire camera,
is encapsulated within an air compartment within the camera housing.
This design has the advantage that the camera optics do not need
to be redesigned for atmospherically-based usage, but the disadvantage
is that there will be a pressure differential between the outside
water pressure and lower gas (air) pressure inside the compartment,
which will, at some depth, become a limiting factor in the design.
However, even this design is operable at depths of five hundred
feet (500') with the use of only inexpensive plastic materials because
the housing is made from a single piece of cast plastic with no
openings or seals. There is thus no problem with leakage which exists
with conventional 0-ring seal designs for underwater cameras.
In another embodiment of an underwater camera in accordance with
the present invention, the entire camera is embedded in an optically
clear plastic potting material (such as polycarbonate), including,
most notably, the (focus-free) optics of the camera. When the camera
is delivered into use this potting plastic is solid, and permanent.
In a variant of this embodiment the camera, and more normally the
camera and the entire interior of the watertight case within which
it and any accompanying auxiliary electronics are housed, is filled
with a clear liquid, normally ethanol.
This embodiment, and both these variants, have the disadvantage
that the camera optics have to be designed for the different index
of refraction of the clear plastic potting material, or the liquid,
as opposed to air. Also, if the potting plastic solidifies hard
(which is normal), then there cannot be any moving parts, making
that the camera optics have to be focus-free, and unmoving. When
the camera enclosure is filled with a clear dielectric fluid then
mechanical focusing of the camera optics is still permitted. However,
care has to be taken in that (1) the immersion fluid is not normally
a satisfactory lubricant, (2) material from the camera may become
dissolved and/or dispersed in the fluid, clouding its clarity and
interfering with photography, and/or (3), depending upon the differential
compressibility of the immersion fluid versus water, the fluid may
still slightly compress and the camera body distort at very great
depths, normally a mile or more.
The advantage of the second embodiment is that an inexpensively
housed and adapted conventional digital electronic camera can be
made to be operable at essentially any depth. This is because a
total absence of air inside the camera housing precludes that any
pressure differential should arise between the outside and the inside
of the camera. The fact that this can be achieved with an inexpensive
design makes this embodiment of an underwater camera in accordance
with the present invention particularly novel and attractive.
8. A Variant Embodiment Underwater Electronic Digital Camera Communicating
Digital Data Via Radio
A cross-sectional top plan view, similar to FIG. 1, of variant
preferred embodiment of a waterproof digital electronic camera la
according to the present invention is shown in FIG. 8. This variant
embodiment system la communicates digital information via a radio
link.
A digital camera 11 is again preferably Kodak type DC 210. The
RS-232(C) interface 174 to this camera now connects to, and through,
2.4 GHz spread-spectrum transceiver modules 373 to an external personal
computer, or PC, 4. The preferred 2.4 GHz spread-spectrum transceiver
modules 373 are type DG24RFA from the extensive DGRO/DRG24 families
of board level radio frequency transceiver modules available from
FreeWave Technologies, Inc. Radio data transmission may transpire
at speeds up to 115.2 kbaud.
9. Recapitulation, and Extension, of the Concepts of the Present
Invention
There are at least four primary features to the waterproof digital
electronic camera system of the present invention. First, the method
of designing the housing within the housing accords for an air space
which contains the camera or at least the camera optics. Second,
the design of the electronic switches permits operator control of
the camera while it is submerged nonetheless that this these switches
require no holes through the housing whatsoever, thus preserving
the water-tight integrity of the housing. Third, the method of recharging
the battery of the camera does not require opening of the housing,
nor the presence of any holes in the housing. Fourth, the infrared
optical interface to a communicating PC requires neither any opening
of the housing, nor any openings in the housing.
These concepts of the present invention described herein this specification
are of broad applicability. Namely, the concepts of (i) potting
the auxiliary electronics and the digital electronic camera together
to provide an inexpensive watertight housing, (ii) magnetically
activating essential switches of the both the momentary and dual-state
types, (iii) communicating data to a computer upon an infrared optical
data interface through a clear housing, (iv) breaking or otherwise
disrupting a frangible or removable seal to optionally replace a
battery, (v) filling the housing with a dielectric fluid which may
either remain liquid or solidify, and (vi) still other concepts,
can all be applied to diverse underwater devices other than digital
electronic cameras.
For example, an underwater light could be made using these design
features. Also, when an all-digital video camera with no moving
parts becomes a reality, this video camera can be housed the same
way, and the pictures retrieved to a computer interface, in the
identical manner as the digital electronic still camera of the present
invention.
Accordingly, the concepts of the present invention should be understood
to be broadly applicable to digital electronic equipments deployed
in underwater, marine, adverse weather and contaminated environments
of various natures.
By way of a further particular example, and underwater digital
watch can greatly benefit by several of the concepts of the present
invention. The watch may employ each and any of the (i) encapsulating
housing, (ii) inductively coupled battery recharging, and/or (ii)
magnetically actuated switching concepts of the present invention.
The may be, in particular, completely potted and sealed in strong
plastic for underwater operation.
In accordance with the preceding explanation, variations and adaptations
of the hermetically sealed digital electronic camera system in accordance
with the present invention will suggest themselves to a practitioner
of the electronics and optics packaging arts. For example, data
could be communicated to and from the camera over and inductive
electrical link in the manner of U.S. Pat. No. 5,455,466. A design
need not embrace each and every disparate aspect of the present
invention to be within the scope of the invention, as defined by
the attached claims. At least when the battery is not replaced,
the underwater camera of the present invention is the first, to
the inventor's knowledge, to house a function camera in a case that
is totally without such holes, or orifices, as have commonly previously
fitted mechanisms for transmitting mechanical forces, or wires for
communicating electrical power and/or signals. Even if the battery
replacement option is employed, the hermetically sealed digital
electronic camera system of the present invention can fairly be
described as "seal-less" in that its case, while certainly
"sealed", has no "seals" in the sense that some
crack or orifice through which water and/or contamination might
otherwise enter has to be "patched over" with a "seal"
that otherwise permits the movement of something--mechanical force
or electricity or whatever--through the region of the seal.
In accordance with these and other possible variations and adaptations
of the present invention, the scope of the invention should be determined
in accordance with the following claims, only, and not solely in
accordance with that embodiment within which the invention has been
taught.
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