Digital Camera Patent

Digital camera having overlapped exposure

Digital Camera Patent Abstract

A digital camera includes a shutter button. When taking a still picture of a subject in response to operation of the shutter button, a TG carries out first exposure and second exposure. The first exposure and the second exposure are simultaneously started by the suspension of outputting a charge sweep-out pulse. Elapsing a first exposure period, the TG reads a first charge out of a part of the light-receiving elements, thereby ending the first exposure. Elapsing a second exposure period, a mechanical shutter is closed thereby ending the second exposure. A second charge produced due to the second exposure is read out after completing the transfer of the first charge. The first and second charges outputted from the CCD imager are combined together by an image combining circuit.

Digital Camera Patent Claims

What is claimed is:

1. A digital camera comprising: an image sensor formed, in a light-receiving surface, with a plurality of first light-receiving elements and a plurality of second light-receiving elements; a first exposer for subjecting said first light-receiving elements to first exposure for a first period; a second exposer for subjecting said second light-receiving elements to second exposure for a second period; an outputter for separately outputting, from said image sensor, a first charge produced in said first light-receiving elements due to the first exposure and a second charge produced in said second light-receiving elements due to the second exposure; and a generator for generating a still image signal of one screen on the basis of said first charge and said second charge, wherein said first period starts simultaneously with said second period, is shorter than said second period and is overlapped in time with said second period, said digital camera further comprising a first applier to apply a first charge read pulse to said first light-receiving elements, a second applier to apply a second charge read pulse to said second light-receiving elements, a third applier to apply a single charge sweep-out pulse to both said first light-receiving elements and said second light-receiving elements, and a shutter member to mechanically cut off incident light on said light-receiving surface, wherein said first exposer controls any two of said first applier, said third applier and said shutter member to carry out the first exposure while said second exposer controls any two of said second applier, said third applier and said shutter member to carry out the second exposure, and wherein said first exposer controls start and end time points of the first exposure by said first applier and said shutter member, respectively, and said second exposer controls start and end time points of the second exposure by said third applier and said shutter member, respectively.

2. A digital camera, comprising: an image sensor formed, in a light-receiving surface, with a plurality of first light-receiving elements and a plurality of second light-receiving elements; a first exposer for subjecting said first light-receiving elements to first exposure for a first period; a second exposer for subjecting said second light-receiving elements to second exposure for a second period; an outputter for separately outputting, from said image sensor, a first charge produced in said first light-receiving elements due to the first exposure and a second charge produced in said second light-receiving elements due to the second exposure; a generator for generating a still image signal of one screen on the basis of said first charge and said second charge, wherein said first period is shorter than said second period and overlapped in time with said second period; and a color filter arranged with a plurality of color elements covering said light-receiving surface, wherein the colors are assigned to both the first light-receiving elements and said second light-receiving elements, and wherein said color filter comprises a plurality of color blocks including each of the colors, said first and second light-receiving elements being alternately arranged, in a predetermined number in each, in at least one of the vertical and horizontal directions, each of the color elements individually corresponding to each of said first and second light-receiving elements, and the predetermined number being coincident with the number of color elements of the color block in a direction said first and second light-receiving elements are alternately arranged.

3. A digital camera, comprising: an image sensor of an interline-transfer type having a light-receiving surface on which a plurality of light-receiving elements and a plurality of vertical transfer registers are formed; a color filter which is arranged with a plurality of color elements respectively corresponding to said plurality of light-receiving elements; a shutter member for mechanically cutting off incident light on said light-receiving surface; a first exposer for subjecting first light-receiving elements, which are a part of said plurality of light-receiving elements, to first exposure for a first period; a second exposer for subjecting second light-receiving elements, which are another part of said plurality of light-receiving elements, to second exposure for a second period; an outputter for separately outputting, from said image sensor, first charges produced by the first exposure and second charges produced by the second exposure; and a generator for generating a still image of one screen on the basis of the first charges and the second charges which are outputted by said outputter, wherein each of said plurality of color elements has any one of a plurality of colors, said plurality of color elements are formed of a plurality of color blocks to each of which all the plurality of colors are assigned, said plurality of light-receiving elements are alternated in a specific direction between the first light-receiving element and the second light-receiving element every predetermined number, the predetermined number is coincident with the number of color elements existing in the specific direction within each of said plurality of color blocks, and the first period is shorter than the second period and is overlapped in time with the second period.

4. A digital camera according to claim 3, further comprising: a first applier for applying a first charge read pulse to said first light-receiving elements; a second applier for applying a second charge read pulse to said second light-receiving elements; and a third applier for applying a charge sweep-out pulse to said first light-receiving elements and said second light-receiving elements, wherein said first exposer controls any two of said first applier, said third applier and said shutter member to carry out the first exposure while said second exposer controls any two of said second applier, said third applier and said shutter member to carry out the second exposure.

5. A digital camera according to claim 4, wherein said first exposer controls start and end time points of the first exposure by said third applier and said first applier, respectively, and said second exposer controls start and end time points of the second exposure by said third applier and said shutter member, respectively.

6. A digital camera according to claim 4, wherein said first exposer controls start and end time points of the first exposure by said first applier and said shutter member, respectively, and said second exposer controls start and end time points of the second exposure by said third applier and said shutter member, respectively.

7. A digital camera according to claim 3, wherein said image sensor is a CCD imager.

8. A digital camera according to claim 3, wherein the specific direction is one of a vertical direction and a horizontal direction.

Digital Camera Patent Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to digital cameras and, more particularly, to a digital camera which generates a still image signal of one screen on the basis of the first charge produced due to first exposure by the image sensor and the second charge produced due to second exposure by the image sensor.

2. Description of the Prior Art

There is an example of a conventional digital camera of this kind as disclosed in Japanese Patent Laid-open No. 75118-1999[H04N5/335, H04N5/232] laid open on Mar. 16, 1999. This prior art aims at generating a still image signal extended in dynamic range by combining the charge acquired by long-time exposure and the charge due to short-time exposure. In the prior art, however, the short-time exposure is carried out after the completion of the long-time exposure. This increases the total time needed for exposure, thus resulting in a blurred picture taken of a subject moving at high speed.

SUMMARY OF THE INVENTION

Therefore, it is a primary object to provide a digital camera capable of preventing against a blurred picture taken of a subject.

A digital camera according to the present invention comprises: an image sensor formed, in a light-receiving surface, with a plurality of first light-receiving elements and a plurality of second light-receiving elements; a first exposer for subjecting the first light-receiving elements to first exposure for a first period; a second exposer for subjecting the second light-receiving elements to second exposure for a second period; an outputter for separately outputting, from the image sensor, a first charge produced in the first light-receiving elements due to the first exposure and a second charge produced in the second light-receiving elements due to the second exposure; and a generator for generating a still image signal of one screen on the basis of the first charge and the second charge; wherein the first period is shorter than the second period and overlapped in time with the second period.

The total exposure period is shortened by the overlap in time of the first and second periods. This suppresses blurring in a picture taken of a subject moving at high speed. Also, the dynamic range is enlarged by generating a still image signal of one screen on the basis of the first and second charges produced by exposures different in period.

In one example of the invention, a first applier applies a first charge read pulse to the first light-receiving elements, a second applier applies a second charge read pulse to the second light-receiving elements, and a third applier applies a charge sweep-out pulse to the first light-receiving elements and the second light-receiving elements. Meanwhile, a shu