JPH0299930A - Electronic camera - Google Patents

Abstract

PURPOSE:To set an optimum exposure condition and to miniaturize and simplify the constitution of the title camera by supplying the detecting signal of a photometry element and the video signal of an image sensor to the same A/D converter, and setting shutter speed with an output signal from the A/D converter at the time of photometry. CONSTITUTION:An electronic camera is provided with a switching means 15 by which the output signal of the photometry element 14 is supplied to the A/D converter 16 at the time of photometry and the output signal of the image sensor 13 is supplied to the same A/D converter 16 at the time of photographing. The electronic camera is provided with a shutter speed control means 19 which set the optimum shutter speed of the electronic shutter by a mechanical shutter 12 or an image sensor 13 itself based on the output signal from the A/D converter 16 at the time of the photometry and constituted so that photographing is carried cut under the optimum exposure condition. Simultaneously shutter speed can be controlled with high accuracy through digital signal processing. Thus, the constitution of the camera can be miniaturized and simplified.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention captures an image with a color image sensor having a photoelectric conversion function, and converts the video signal generated by the imaging into a digital signal and records it. Regarding electronic cameras.

[Conventional technology]

Conventionally, as such an electronic camera, Japanese Patent Laid-Open No. 59-18
There is one shown in No. 3582. This electronic camera is
As shown in Figure 3, there is an optical system 1 that forms an optical image of a subject, and a color image sensor (surface An analog video signal is read out by horizontally and vertically scanning the color image sensor 2 in synchronization with a drive signal output from a driver circuit 3. The analog video signal read out by this scanning is converted into a digital signal by the A'/D converter 4, and is stored in the semiconductor memory 5 in synchronization with the address signal at a predetermined timing output from the driver circuit 6 and in correspondence with the pixel arrangement. It is supposed to be done. In the present invention, an electronic viewfinder function is provided by supplying a video signal to an electronic viewfinder 9 via a D/A converter 7 and a switching circuit 8, and outdoor photography using a battery 10 is made possible.

[Problem to be solved by the invention]

In such an electronic camera, it is necessary to set the optimum exposure state using a shutter or aperture (not shown) in the optical system 1. In particular, if a photograph is taken with an exposure amount that deviates from the optimum state, the image may become distorted. This may cause problems such as the inability to record good video due to limitations in the dynamic range of the sensor 2 and the signal processing system connected to it.
It is desired to develop a more precise exposure control means.

[Means to solve the problem]

The present invention has been made in view of such problems,
It is an object of the present invention to provide an electronic camera having a simple structure and having a highly accurate exposure control means.

In order to achieve this object, the present invention supplies an output signal of a photometric element to an A/D converter during photometry, and supplies an output signal of an image sensor to the same A/D converter during photography. and a shutter control means for setting an optimum shutter speed of a mechanical shutter or an electronic shutter by the image sensor itself based on an output signal from the A/D converter during photometry. The camera is configured to take pictures under optimal exposure conditions.

[Effect]

In the present invention having such a configuration, the optimum exposure state can be set by the photometry means and the shutter control means, and the accuracy can be improved by digital signal processing in the shutter control means. Furthermore, since the output signal of the image sensor and the output signal of the photometric element are generated by the same A/D converter, the configuration can be made compact and simple.

〔Example〕

An embodiment of the present invention will be described below with reference to FIG. First, to explain the configuration, in the figure, a mechanical shutter 12 and a CC
A color image sensor 13 consisting of D, etc. is arranged in sequence, and an optical image of a subject incident through the optical system 11 passes through a mechanical shutter 12 and is sent to the color image sensor 1.
It is designed to form an image on 3. Furthermore, a photometric element 14 for photometry such as a phototransistor is provided in a separate light input section.

Reference numeral 15 denotes a switching means consisting of an analog switch, etc., in which the video signal read out from the color image sensor 13 is transmitted to the switching contact a, and the detection signal of the photometric element 14 is transmitted to the switching contact 2. Contact a
, b selectively transfers one signal to the output contact C.

16 is an A/D converter, which converts the signal at the output contact C into a digital signal.

Reference numeral 17 denotes a video signal processing circuit, which performs so-called γ correction and white balance adjustment on the digital video signal output from the A/D converter 16, separates the luminance signal and color difference signal, and generates a readable and writable random signal. Access memory (RA
M) is stored in the card-type memory device 18 containing the file.

The output terminal of the A/D converter 16 is connected to the shutter control circuit 19.
The shutter control circuit 19 is also connected to the A/D converter 1.
A shutter speed for setting the optimum exposure amount is set in the mechanical shutter 12 according to the digital detection signal outputted from the shutter 6. That is, the mechanical shutter 12 does not operate at the set speed due to mechanical factors such as collisions between shutter blades, so the mechanical shutter 12 does not operate at the set speed. Control is performed to automatically adjust the actuation timing of the shutter 12.

Reference numeral 20 denotes a drive circuit that generates a drive signal for outputting the video signal generated in each pixel of the image sensor 13 by so-called vertical and horizontal scanning readout.

Reference numeral 21 denotes a central control circuit incorporating a microcomputer, etc., which controls the switching operation of the switching means 15, the processing operation of the video signal processing circuit 17, the writing operation of the memory device 18, the operation of the shutter control circuit 19, and the driving of the drive circuit 20. The timing of each operation is centrally controlled.

Next, the operation of this embodiment will be explained. First, when the shutter speed is set and the shutter release button (not shown) is pressed, the switching means 15 switches to the switching contact side, and the light intensity detected by the photometric element 14 from the subject is detected. Signal switching contact b~
The signal is transmitted to the A/D converter 16 via C. The A/D converter 16 converts it into a digital detection signal and supplies it to the shutter control circuit 19, and the shutter control circuit 19 adjusts the operation timing of the mechanical shutter 12 to obtain the optimum exposure amount corresponding to the set shutter speed. Make corrections.

Next, the mechanical shutter 12 performs a shutter operation at a shutter speed that includes the correction value to take a photograph.

Next, the switching means 15 switches to the switching contact a side, and the signal charge generated in each pixel of the image sensor 13 by this photographing is read out in synchronization with the drive signal from the drive circuit 20, thereby producing a video signal. is transmitted to the A/D converter 16 via switching contacts a-c. A/
The D converter 16 converts the video signal into a digital signal and supplies it to the video signal processing circuit 17, and the video signal processing circuit 17 forms a luminance signal and a color difference signal of the NTSC system through digital arithmetic processing and stores them in the memory device 18. let

In this way, this embodiment can set the optimum exposure condition by correcting the timing of the shunter operation caused by the mechanical structure of the mechanical shutter 12, and furthermore, by providing the switching means 15, one A/
Since the D converter 16 enables two different signal processing systems, the structure can be simplified.

Next, another embodiment will be described with reference to FIG. In this figure, the same or corresponding parts as in FIG. 1 are indicated by the same reference numerals.

This embodiment relates to an electronic camera in which the image sensor 13 itself performs a shutter operation.

That is, this image sensor 13 is composed of an interline transfer type charge storage device (CCD), and has a period during which signal charges generated in a group of light receiving elements constituting a pixel are transferred to a vertical transfer path (i.e., a light receiving period). By controlling it, a substantial shank operation is performed. Therefore, no mechanical yutter is provided. Even in such an electronic printer, a phenomenon occurs in which the transfer timing of the signal charge shifts depending on the shutter speed, so the shutter control circuit 19 corrects this and sets the optimum exposure amount.

In the above two embodiments, a circuit configuration in which one A/D converter is used for digital conversion of the video signal and the photometric detection signal is shown, but the digital detection signal to the shutter control circuit is used for aperture adjustment. It may also be applied to signals.

Further, although the case where a memory device containing a semiconductor memory is used as a recording medium has been described, the present invention can also be applied to an electronic camera using a magnetic recording medium.

〔Effect of the invention〕

As explained above, according to the present invention, an image sensor that receives an optical image of a subject and outputs a video signal for each pixel, a photometric element that detects the light intensity of the optical image of a subject, and an A/D
In an electronic camera having a converter, switching means supplies a detection signal of a photometric element to an A/D converter during photometry, and supplies a video signal of an image sensor to the same A/D converter during shooting; , shutter control means for setting the shutter speed of a mechanical shutter or an electronic shutter by the image sensor itself based on the output signal from the A/D converter during photometry, so that the optimum exposure state can be set. In addition, it is possible to improve accuracy by digital signal processing in the shutter control means. Furthermore, since the output signal of the image sensor and the output signal of the photometric element are generated by the same A/D converter, the configuration can be made compact and simple.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment according to the present invention; FIG. 2 is a block diagram of another embodiment; FIG. 3 is a block diagram of a conventional example. In the figure: 12; Mechanical shutter 1〇- Color image sensor Photometric element switching means A/D converter Video signal processing circuit Memory device Shutter control circuit Drive circuit Central control circuit frame

Claims (1)

[Scope of Claims] An electronic camera having an image sensor that receives an optical image of a subject and outputs a video signal for each pixel, a photometric element that detects the light intensity of the optical image of the subject, and an A/D converter. , switching means for supplying the detection signal of the photometric element to the A/D converter during photometry and supplying the video signal of the image sensor to the same A/D converter during photography; An electronic camera characterized by comprising shutter control means for setting the shutter speed of a mechanical shutter or an electronic shutter by the image sensor itself based on an output signal from an A/D converter.