JPH04317275A - Image pickup device - Google Patents

Abstract

PURPOSE:To obtain an image having large depth of field in short accumulation time even for the image with low frightness by controlling the amplification factor of an amplification means and the charge accumulation time of an image pickup element by means of the detection value of a detection means and the photometric value of a photometric means. CONSTITUTION:When a user selects a depth on field priority mode, a CPU 8 detects the signal of a mode detection part 10, reads out the signal of a depth of field detection part 11, and calculates an aperture value from the detection result. At the same time, it reads the photometric value of a photometric part 9 and calculates the charge accumulation time and the amplification factor of an amplifier 5. After calculating an aperture value from the signal of the depth of field detection part 11, the CPU 8 changes the aperture value and the accumulation time so that the appropriate exposure can be obtained with sensitivity fixed. Then it fixes the aperture value and the accumulation time, changes the amplification factor of the amplifier 5 to change the sensitivity so that the under-exposure can be compensated.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an imaging apparatus having means for amplifying a video signal from an imaging element with a variable amplification factor.

0002

2. Description of the Related Art Conventionally, cameras have been known that have a shooting mode that prioritizes depth of field and use silver halide film as a recording medium. In such a camera, when the photographer determines the depth of field, an aperture value is calculated inside the camera, and an exposure time is determined based on the aperture value and the photometric value.

0003

[Problems to be Solved by the Invention] However, with the above-mentioned conventional cameras, when the depth of field required by the photographer is deep and the subject is low-luminance, the camera requires a long exposure time in order to obtain sufficient exposure. ■. Exceeding the limits of camera shake.

[0004]■. In continuous shooting mode, the continuous shooting speed becomes slower. There were such issues.

SUMMARY OF THE INVENTION In view of the above-mentioned problems, an object of the present invention is to provide an imaging device such as an electronic still camera that can obtain an image with a deep depth of field in a short storage time even for a low-luminance object. There is a particular thing.

[0006]

[Means for Solving the Problems] The imaging device of the present invention includes a photometry means for detecting the brightness of an object, a detection means for detecting the depth of field, and an amplification device for amplifying the charge of the image sensor with a variable amplification rate. and controlling the amplification factor of the amplification means and the charge accumulation time of the image pickup device based on the detection value of the detection means and the photometry value of the photometry means.

[0007]

[Operation] The present invention controls the charge accumulation time of the image sensor and the amplification factor of the charge amplification means based on the depth of field and the photometric value. This makes it possible to obtain images with a deep depth of field.

[0008]

Embodiments Hereinafter, embodiments of the present invention will be explained in detail with reference to the drawings.

FIG. 1 is a block diagram showing the basic configuration of an embodiment of an electronic still camera using the present invention. 1 is
In the optical lens, 2 is the aperture. Optical lens 1, aperture 2
The image projected through the image sensor 3 is converted into electric charges in the image sensor 3, and sent to the amplifier 5 by the image sensor driver 4. The signal output from the amplifier 5 is converted into an appropriate format by the signal processing section 6 and stored in the storage section 7. The storage unit 7 uses a disk, a memory, or the like as a storage carrier. The CPU 8 drives or controls each of the blocks.

9 is a photometering unit that detects the brightness of the subject; 1
0 is a mode detection unit that detects a mode such as normal mode or depth of field priority mode. 11 is a depth of field detection unit that detects the depth of field, and has a method of reading out a preset value,
A method may be considered in which the photographer selects the depth by operating a switch or the like.

The operation of the electronic still camera configured as described above will be explained next.

When the photographer selects the depth of field priority mode, the CPU 8 detects the signal from the mode detection section 10, reads the signal from the depth of field detection section 11, and calculates the aperture value from the detection result. do. At the same time, the photometric values of the photometric section 9 are read, and the charge accumulation time and the amplification factor of the amplifier 5 are calculated from these results.

FIG. 2 is an example of a program diagram showing such an operation, where Av is the aperture value, Tv is the charge accumulation time, and Bv
is the brightness of the subject. Sv is the sensitivity, and the sensitivity can be changed by changing the amplification factor of the amplifier 5.

In such a coordinate system, the CPU 8
When the aperture value is calculated as Av2 or more from the signal of the depth of field detection section 11, the output of the photometry section 9 becomes Bv1 to Bv2 (Bv1
>Bv2), the aperture value (Av1 to Av2) and the storage time (Tv1 to Tv2) are changed, and the sensitivity Sv1 is kept fixed and controlled so that appropriate exposure can be obtained. Tv2 at this time is a value determined from camera shake, continuous shooting speed, etc.

The output of the photometer 9 is Bv2 to Bv3 (Bv2
>Bv3), the aperture value and accumulation time are each Av.
2, Tv2 is fixed, and the amplification factor of the amplifier 5 is changed to change the sensitivity and compensate for the lack of exposure.

In the embodiment described above, an electronic shutter method is assumed as a method for controlling the accumulation time, but there is no difference even if a mechanical shutter method is used. Further, the present invention is not particularly limited to electronic still cameras, but can be used in imaging devices having means for amplifying video signals from an imaging device with variable amplification factors, such as 8 mm video.

[0017]

[Effects of the Invention] As explained above, according to the present invention,
By controlling the charge accumulation time of the image sensor and the amplification factor of the amplification means based on the depth of field and photometric values, images with a deep depth of field can be obtained in a short accumulation time even for low-brightness subjects. be able to.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the basic configuration of an embodiment of an electronic still camera using the present invention.

FIG. 2 is a program diagram in a depth of field priority mode of an embodiment of an electronic still camera using the present invention.

[Explanation of symbols]

1 Optical lens 2 Aperture 3 Imaging device 4 Drive section 5 Amplifier 6 Signal processing section 7. Storage section 8 CPU 9 Photometry section 10 Mode detection section 11 Depth of field detection section

Claims (1)

[Claims] 1. A photometer that detects the brightness of a subject, a detection device that detects the depth of field, and an amplification device that amplifies the charge of an image sensor with a variable amplification rate, the detection device of the detection device An imaging apparatus characterized in that the amplification factor of the amplification means and the charge accumulation time of the image pickup element are controlled based on the photometry value of the photometry means and the photometry value of the photometry means.