JPS62203486A - Image pickup device - Google Patents

Abstract

PURPOSE:To successively vary an image pickup direction and to recognize by a display a shadow image pickup or not in case zooming is performed by providing the first and the second gate means, a detection mixing means, a comparison means, and a display means. CONSTITUTION:Video signals respectively supplied to integrating circuits 22, 23 are integrated herein, smoothed, and thereafter detected in detection circuits 24, 25, respectively. Thereby, the detection circuits 24, 25 respectively output the average voltage of the video signals of an upper part 21a and a central part 21b in a picture 21. The output average voltage of the respective detection circuits 24, 25 is held for a fixed period in direct current hold circuits 33, 34. The output average voltage of the direct current hold circuit 33 is adjusted in level in a variable resistance 26, supplied to the mixer 27 thereafter, herein, the output average voltage of the direct current hold circuit 24 is subtracted and mixed to obtain a difference voltage. The difference voltage is supplied to the inverse input terminal of the comparator 28. When the output of the comparator 28 goes to an H level, a current passes through a light emitting diode 30, it emits light to display the shadow image picking up state.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a mud statue neck, and more particularly to an AD statue neck mounting that uses an automatic aperture function.

2. Description of the Related Art Imaging devices such as Piteo cameras are equipped with an automatic iris device for proper exposure.

The automatic aperture device described above performs photometry by detecting the average value or peak value of the video signal obtained by the imaging device, and opens and closes the aperture at aIl+nu L. The photometry described in F includes full-surface photometry that detects the video signal uniformly over the entire screen, center-weighted photometry that detects the video signal only in the center of the screen, and center-weighted photometry as described in JP-A-58-111489. There are photometry methods such as photometry.

Normally, by metering the frame and controlling the aperture, it is possible to obtain the optimal exposure for that frame. In such cases, full-plane photometry would make the subject too dark, so center-weighted photometry or center-weighted photometry is used.

The problem IId that the invention seeks to solve is that imaging is performed to produce an image to be displayed in a viewfinder. However, when the imaging direction of the camera is continuously tilted or when zooming to capture an ILD image, the only person looking at the image displayed in the viewfinder must be able to determine whether the camera is backlit or not. No. 1 - It's always difficult to do.

However, even if it is determined that there is backlight, at that point the aperture must be adjusted by operating a predetermined switch, which is a problem in that the operation is time-consuming.

Therefore, the present invention provides first and second gate means.

It is an object of the present invention to provide an imaging ia that solves the above problems by using a detection mixing means, a comparison means, and a display means or a blanking means.

Means for Solving the Problems In the first invention, the first gate means extracts a video signal of a predetermined part different from the center part of the screen from the image No. 42 obtained by the eye image. 2 goo]・By means,
From the video signal obtained by imaging, the video signal of the central part where the subject is located is extracted.

The detection and mixing means obtains a difference signal between a signal obtained by detecting the output video No. 15 of the first gate means and a signal obtained by detecting the output movie signal of the second gate means. The comparison means compares the difference signal with the reference signal to detect backlight. The display means displays the backlit image state based on the output signal of the comparison means.

In the second invention, the output signal of the comparison means is supplied to the blanking circuit, and when the backlit image state is instructed, the blanking circuit detects the portion of the screen where the backlit light source is located based on the video signal obtained by imaging. The video signal is removed and supplied to a detection circuit for automatic aperture adjustment.

In the first operation 11, whether or not the image is a backlit l!i2 image is detected by the comparison means and displayed on the display means.

In addition, in the second invention, the image No. 11 of the light source part is blanked in the backlight "1," and the automatic aperture adjustment is performed using the detection output of the blanked video signal, so that the exposure suitable for the brightness of the subject is adjusted. It becomes possible.

Embodiment FIG. 1 shows a block system diagram of an embodiment of an imaging apparatus according to the first invention. This video signal is supplied to a detection circuit 11 and gate circuits 12 and 13, respectively.

The detection circuit 11 performs, for example, peak detection on the supplied full-screen video signal, and narrows down the obtained detected signal to the circuit 1
Supply to 4. The aperture control circuit 14 generates a control signal according to the level of the detected signal and supplies it to the aperture mechanism 15, which in turn adjusts the aperture to an opening degree according to the control signal.

A vertical synchronization signal VD, a horizontal synchronization signal 1"D, and a clock signal GK are input to the terminals 16, 17, and 18, respectively, to the synchronization signal generation circuit (not shown) in the imaging device. are supplied to counters 19 and 20, respectively. The above-mentioned clock signal is a signal with a sufficiently short period compared to the water-V Kaimei No. 3 1''D signal.

Counters 19 and 20 each include a first counter that outputs a pulse of the horizontal synchronization signal HD after being reset by the vertical synchronization signal (No. 3 Vl), and a first counter that outputs a pulse of the clock signal after being reset by the horizontal synchronization signal HD. and a second counter for counting. The counter 19 receives the horizontal synchronizing signal 1-I shown in FIG. 3(A) during the H level period of the signal of the waveform shown in FIG. Figure 3 synchronized with D ([3)
A gate signal having a waveform shown in is generated and supplied to the goo 1-circuit 12.

Further, the counter 20 has a second counter synchronized with the vertical synchronization signal VD.
During the 14 level period of the signal with the waveform shown in Figure (C),
A gate signal having the waveform shown in FIG. 3(C) synchronized with the horizontal synchronizing signal 1-ID is generated and supplied to the gate circuit 13.

The gate circuit 12 extracts the video signal coming from the terminal 10 only during the H level period of the gate signal from the counter 19. Therefore, the video signal on the upper part 21a of the screen 21 shown in FIG. 4 (A>) is taken out. The gate circuit 13 receives the goo 1 from the h-counter 20 and supplies it to the integrating circuit 22.
- Takes out the video signal that enters the terminal 10 only during the I'' level period of the signal. Therefore, the video signal of the central portion 21b of the screen 21, not shown in FIG. 4(B), is taken out and supplied to the integrating circuit 23.

The video signals supplied to each of the integration circuits 22 and 23 are integrated and smoothed here, and then detected by each of the detection circuits 24 and 25. As a result, the detection circuits 24 and 25 each output the average voltage of the video signal of the upper part 21ε1 and the center part 21b within the screen 21. The average output voltage of each of the detection circuits 24 and 25 is held for a certain period of time by each of the DC hold circuits 33 and 34.

The average output voltage of the DC hold circuit 33 is determined by the variable resistor 26.
After level adjustment, the voltage is supplied to the U combiner 27, where the output average voltage of the DC hold circuit 34 is subtracted and mixed by 0 to obtain a differential voltage. This differential voltage is supplied to the inverting input terminal of comparator 28.

A reference voltage is supplied from a variable resistor 29 to a non-inverting input terminal of the comparator 28, and the comparator 28 is connected to a Zener diode Dz and has hysteresis characteristics.

By the way, in front lighting 111a where the light source is behind the camera, the brightness of the subject at the center 21b of the screen 21,
The difference from the background glow melon in the upper part 21a of the screen 21 is small. When backlighting ftifm, in most cases, the bright sky and the sun appear at the top 21a of the screen 21.

Because there is a light source such as a fluorescent lamp or light, the back of the upper part 21a
The brightness is higher than the brightness of the subject in the central portion 21b.

Therefore, the output of the comparator 28 becomes H level when the light is backlit, and becomes L level when the light is forward lit. In addition, comparator 2
The reason why the hysteresis characteristic is given to the comparator 28 is to prevent chattering from occurring in the output of the comparator 28 when the imaging direction slightly changes while the differential voltage output from the mixer 27 is approximately the same as the reference voltage. This is to do so.

When the output of the comparator 28 becomes 1 to 1000 lb, a current flows to the light emitting diode 30, which emits light and backlights MAf'
It will display that it is in li state. When the user recognizes that there is backlight from this display and performs a predetermined switch operation, for example, the user operates the aperture control circuit 14 from the terminal 32 (
No. 3 is supplied, and the aperture control circuit 14 changes the aperture in the direction of opening it. As a result, an image is captured with an exposure suitable for the subject in the center portion 21b of the screen 17.

Note that the output signal of the comparator 28 taken out from the terminal 31 is supplied to, for example, an on-screen circuit (not shown), where a video signal for displaying characters 1, backlight 1, etc. is generated, and this video signal V) is It is mixed with the image obtained from the image pickup tube or the decoy IgI and supplied to the electronic viewfinder (I!
etc. may be displayed.

FIG. 5 shows a block system diagram of an embodiment of the km system fj7+ according to the second invention. In the figure, the same parts as in FIG. 1 are designated by the same reference numerals, and their explanations will be omitted.

In FIG. 5, an image signal from an X-J6 image pickup tube or an image pickup device is supplied to a terminal 10 to gate circuits 12 and 13, and is also supplied to a blanking circuit 4. Also,
The gate signal outputted by the counter 19 is Goo 1 - Circuit 12
and is supplied to the blanking control circuit +tFI41.

Furthermore, the output signal g of the comparator 28 is supplied to the planning control 211 circuit 41.

The blanking control circuit 41 controls the counter 1 when the output confidence of the comparator 28 becomes 1 level in the backlit va image.
A blanking circuit 40 extracts the gate signal from 9
It is supplied to In other words, the planking 1III control circuit 41 can be constituted by, for example, an AND circuit. The blanking circuit 40 forcibly sets the video signal from the terminal 10 to, for example, a pedestal level when the gate signal supplied from the blanking υ control circuit 41 is at a torque level, and outputs an image of 1m 4A 5'i when the gate signal is at a torque level. The signal is taken out and supplied to the detection circuit 11. Here, comparator 2
When the output signal of 8 is a trubel, the 1 ranking circuit 40
Of course, the video signal from the terminal 10 is supplied directly to the detection circuit 11.

Therefore, for the backlight 11iU F* +cl,
), the video signal of the upper part 21a where there is a backlit light source is blanked, and the upper part 21a is set as a dead band.As a result, the detection circuit 1
1, peak detection is performed on the video signal of the portion 2IC on both sides 21 excluding the above-mentioned 21a. The portion 210 is the central portion 21
The brightness of the subject and its vicinity can be measured accurately, and the detection signal level is higher than that when detecting the entire video signal (Y-) of the screen 21.

It gets lower. Therefore, the aperture is automatically opened by that amount, and exposure-C imaging suitable for the subject in the center portion 21b is performed.

Note that during backlight imaging, the blanking circuit 40
It is also possible to plan a portion other than the central portion 21b and supply only the video signal of the central portion 21b to the detection circuit 11, and the integrating circuits 22 and 23 may not necessarily be installed. The present invention is not limited to the J'' embodiment shown in FIGS. 1 and 5 above.

Effects of the Invention As described above, the first invention includes the first and second gate means, the detection and mixing means, the comparison means, and the display means, so that it is possible to continuously vary the tl[1a direction and zoom. Even when performing a backlit silver image, the display indicates whether it is a backlit silver image or not; 4
It has features such as being easy to understand.

In addition, the 2nd R light uses a blanking means to blank the video signal of the backlit light source area, and automatically adjusts the aperture to the appropriate exposure for the subject in the center of the screen, making it easy to take pictures. have.

[Brief explanation of drawings]

FIG. 1 is a block system diagram of an embodiment of the first invention, FIGS. 2 and 3 are waveform diagrams of an embodiment of each gate signal, and FIG.
The figure is a diagram to explain the photometry range of the screen.
FIG. 1 is a block system diagram of an embodiment of the invention. 11.24.25...Detection circuit, 12.13...Goo 1-circuit, 14...Aperture control circuit, 19.20...
- Counter, 22.23... Integrating circuit, 27... Mixer, 28... Comparator, 30... Light emitting diode, 40... Blanking circuit, 41... Blanking v control circuit, Dz...Zener diode.

Claims (2)

[Claims] (1) In an imaging device that detects a video signal obtained by imaging with a detection circuit and performs automatic aperture adjustment based on the detected signal, a video signal of a predetermined part of the screen different from the center part of the screen is detected from the video signal obtained by imaging. a first gate means for extracting, a second gate means for extracting a video signal of the central part where the subject is located from the video signal obtained by the imaging, and a signal obtained by detecting the output video signal of the first gate means. and a signal obtained by detecting the output video signal of the second gate means, a detection and mixing means for obtaining a difference signal between the output video signal and a signal obtained by detecting the output video signal of the second gate means, a comparison means for detecting backlight by comparing the difference signal with a reference signal, and an output of the comparison means. An imaging device comprising: a display means for displaying a backlight imaging state based on a signal. (2) In an imaging device that detects a video signal obtained by imaging with a detection circuit and performs automatic aperture adjustment based on the detected signal, a video signal of a predetermined part of the screen different from the center part of the screen is detected from the video signal obtained by imaging. a first gate means for extracting, a second gate means for extracting a video signal of the central part where the subject is located from the video signal obtained by the imaging, and a signal obtained by detecting the output video signal of the first gate means. and a signal obtained by detecting the output video signal of the second gate means, a detection and mixing means for obtaining a difference signal between the output video signal and a signal obtained by detecting the output video signal of the second gate means, a comparison means for detecting backlight by comparing the difference signal with a reference signal, and an output of the comparison means. When a backlight imaging state is instructed by a signal, the blanking circuit removes the video signal of the part of the screen where the backlight light source is located from the video signal obtained by the imaging and supplies it to the detection circuit. Characteristic imaging device.