KR950006046B1 - Image sensing device - Google Patents

Abstract

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Description

Imager

1 is a circuit block diagram of an image pickup apparatus according to an embodiment of the present invention.

2 is a metering area setting pulse circuit according to an embodiment of the present invention.

3 (a) to 3 (e) are signal waveforms in each part, FIG. 3 (a) shows a horizontal synchronization signal, FIG. 3 (b) shows the left end setting signal of the photometric area, and FIG. FIG. 3D is an image signal, and FIG. 3E is a waveform diagram of a metering area image signal.

4 is a diagram showing an example of one setting of the light quantity measuring area on an image pickup screen.

5 is a view showing a light quantity measuring area of a camera for a door phone.

6 is an installation state of the camera for the door phone.

7 is a circuit block diagram of a conventional imaging device.

8 shows a conventional captured screen.

* Explanation of symbols for main parts of the drawings

1: subject 2: optical lens system

3: imaging device 4: preamplifier

5: image signal processing circuit 6: automatic iris control mechanism

15: Image information selection circuit for metering 17: Blank circuit for metering area

18: metering area setting pulse circuit

The present invention relates to an image pickup apparatus capable of backlight compensation for adjusting a cooking system according to the amount of light at a subject position.

Examples of an image pickup apparatus for recording an image by photographing a subject include a video camera, a still image camera using a magnetic disk plate, or an optical camera for photosensitive film.

When photographing using these imaging apparatuses, it is necessary to perform aperture (iris) adjustment to insert an appropriate amount of light into the camera along with focus (focus) adjustment and shutter speed.

Therefore, in the conventional imaging device, an auto iris control mechanism for automatically adjusting the iris in accordance with the image information of the imaging screen is used.

For example, in the conventional video camera, as shown in FIG. 7, the shape of the subject 1 is projected onto an image pickup device 3 such as a CCD through the optical lens system 2. The projected image is photoelectrically converted in the image pickup device 3 to be an electric image signal and sent to the preamplifier 4. The image signal amplified by the preamplifier 4 is subjected to various image signal processing by the image signal processing circuit 5 and output as the video signal 100.

Next, in the automatic iris control mechanism 6 shown in FIG. 7, the image signal processing circuit 5 before mixing the composite synchronous signal 101 in the synchronous signal generator 7 with the video signal 100 is used. The image signal 102 is extracted and used as a feedback signal of the auto iris control mechanism.

The image signal 102 is passed through the low pass filter 8 and then integrated through the detection circuit 9, and thus the average value of the image signal 102 is obtained by converting it into a direct current component. Since this average value is proportional to the average amount of light of the entire captured image, the difference data is obtained by comparing the reference voltage value of the reference voltage source 11 in the voltage comparison circuit 10.

The control circuit 12 then outputs an aperture value according to the difference data, and drives the next driving circuit 13 to adjust the aperture of the imaging device 3. Thereby, the incident light amount of the imaging device was adjusted.

As described above, in the conventional imaging apparatus, the aperture is adjusted according to the average amount of light of the entire captured image, so if the amount of light of the subject and the background is about the same or if the subject occupies most of the captured image, appropriate aperture adjustment for the subject is performed. It will run automatically.

However, for example, as shown in FIG. 8, when there is a light source such as the sun in the background portion of the image pickup screen 14 and the amount of light in the background portion is stronger than that of the subject 1 (i.e., back light), The average amount of light rises. For this reason, the aperture is automatically controlled in the direction of limiting the amount of incident light to the image pickup device, so that the image of the background part is clear, but there is a problem that the important subject 1 becomes dark.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, and to provide an image capturing apparatus in which the iris is automatically adjusted so that a subject is clearly captured even when photographing in a backlight state.

In order to achieve the above object, the present invention provides an image pickup apparatus having an aperture adjusting mechanism for automatically adjusting aperture according to light quantity information of an object to be imaged, comprising: area setting means for setting an arbitrarily designated light quantity reference region in the whole image pickup screen; And extracting means for extracting the light quantity information in the set light quantity reference region from the light quantity information of the entire screen and outputting the extracted light quantity information to the aperture adjusting mechanism.

According to the image capturing apparatus of the above configuration, the aperture control mechanism can be controlled according to only the quantity of light information in the region by arbitrarily designating the quantity of light reference area, so that the image of the subject can be captured at an appropriate exposure by setting the quantity of light reference area on the subject to be captured. You can then run

In other words, even when the backlight is turned on, the aperture control mechanism is properly operated to capture a clear image of the subject.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of an imaging device to which the present invention is applied will be described below with reference to the drawings.

1 is a circuit block diagram showing an image pickup apparatus according to an embodiment of the present invention.

The imaging device of FIG. 1 is a video camera constructed in much the same way as the conventional example shown in FIG. 7. The same reference numerals (1) to (13) in the drawings are denoted by the same reference numerals to omit duplicate explanation. .

The characteristic configuration of this embodiment is that the photometric image information selection circuit 15 for selectively extracting only the image signal in the light quantity measuring area at the predetermined position of the subject among the image signals 102 is provided.

The photometric image information selection circuit 15 is composed of a photometric area blank circuit 17 and a photometric area setting pulse circuit 18 here.

First, the photometric area setting pulse circuit 18 is composed of a circuit as shown in FIG. 2, and the composite synchronous signal 101 sent from the synchronization signal generator 7 of FIG. The signal separation circuit 19 separates the horizontal synchronous signal 104 and the vertical synchronous signal 105.

The horizontal synchronizing signal 104 is input to the A terminal of the monostable multivibrator 20 and triggered on the rising edge to add the resistance CX of the capacitor 21 and the resistance 22 and the variable resistor 23 added thereto. By RX, the output pulse width 200 shown in Fig. 3B is set by the following first equation, and at the Q terminal, the left end setting signal 106 of the photometric area is output. K is an output pulse width constant.

Output pulse width = KRX.CX… … … … … … … … … … … … … … … … … … … … … (Formula 1)

The left end setting signal 106 of the photometric area is input to the B terminal of the next monostable multivibrator 24, and triggers on the falling, so that the capacitor CX of the capacitor 25, the resistor 26 and the variable resistor 27 By the added resistance value RX, the output pulse width 201 shown in FIG. 3C is set by the same formula as in the first equation, and is output as the photometric area right end setting signal 107 at the Q terminal.

The vertical synchronizing signal 105 is also processed in the same manner as the horizontal synchronizing signal 104. That is, the vertical synchronizing signal 105 is input to the A terminal of the monostable multivibrator 28, triggered on the rising edge, and the resistor CX of the capacitor 29 and the resistor 30 and the variable resistor 31 added together. The output pulse width is set by the value similar to the above by the value RX, and is output as the metering area upper limit setting signal 108 at the Q terminal.

The metering area upper end setting signal 108 is input to the B terminal of the next monostable multivibrator 32, and triggers on the falling, which causes the capacitor CX and the resistor 34 and the variable resistor 35 of the capacitor 33 to fall. The output pulse width is set by the same formula as described above by the resistance value RX to which? Is added, and is output as the lower end setting signal 109 at the Q terminal.

The above-mentioned photometric area setting signals in the horizontal and vertical directions are combined in the AND circuit 36 of the next stage, and are inverted in the inverter circuit 37 so as to be blank pulse signals 103 for the photometric area blank circuit 17. Is sent).

In the photometry area blank circuit 17, the image signal in the preset light quantity measurement area among the image signals 102 input from the image signal processing circuit 5 shown in FIG. 1 by the blank pulse signal 103 is used. Only extraction 102 is carried out.

Referring to FIG. 4, these signal processes are set in advance in the light quantity measuring area 16 indicated by hatching in the lower part of the center of the image pickup screen 14. In this embodiment, only the image signal 102 in this area is measured for photometry. The information is selected by the information selection circuit 15.

The extracted signal is output from the photometric area blank circuit 17 of the photometric image information selection circuit 15 as the photometric area image signal 110 shown in FIG. It is input to the filter (8). The signal waveform is as shown in FIG. 3E, for example, and it can be seen that only image signals of a constant region are output.

In this embodiment, the integration is performed through the detection circuit 9 on the low pass filter 8 of the automatic iris control mechanism 6 shown in FIG. 1 using the photometric area image signal 110 obtained as described above. Then, the average value of the photometric region image signal 110 is obtained by converting the signal to a direct current component. This average value is proportional to the average amount of light in the light quantity measuring area 16, and the difference data is taken in comparison with the reference voltage value of the reference voltage source 11 in the voltage comparison circuit 10.

The control circuit 12 outputs a control signal of the drive circuit 13 for adjusting the iris of the imaging device 3 in accordance with this difference data. The drive circuit 13 adjusts the aperture in accordance with the control signal.

As described above, in the imaging device of the present embodiment, for example, the amount of light for adjusting the aperture is determined as the lower mid-point side light at the center of the imaging screen 14, so that the background portion of the imaging screen 14 is shown in FIG. Even when the sun or the sky with a strong light level are photographed and the backlight 1 in which the subject 1 is shaded, the amount of light is measured at the center of the person to determine the aperture value so that the person can be photographed brightly.

That is, when photographing a person or the like, as shown in FIG. 4, the frame setting is naturally performed so as to center the photographing object (here, the person), so that the body part of the person is located below the center of the image pickup screen 14. If the composition is to be increased, and the part is set as the light quantity measuring area 16 in advance, the person (subject) part occupies most of the area, and less of the scenery or the sky enters the area. For this reason, light quantity can be measured centering on the person which is a subject.

Moreover, even when the subject is other than a person, frame setting is performed at the lower portion of the center of the image pickup screen 14, where the scenery, buildings, and the like on the ground naturally enter the subject, not the sun or the sky with a strong light amount. For this reason, if the light quantity measuring area 16 is set below the center of the image pickup screen, in most cases, appropriate automatic iris adjustment can be performed.

As described above, according to the present exemplary embodiment, the aperture can be adjusted according to the subject by setting the light quantity measuring area for adjusting the aperture to the subject position instead of the entire image pickup screen as in the prior art. Images can be obtained.

In the present embodiment, the light quantity measuring region 16 is set below the central portion of the image pickup screen 14, but the present invention is not limited to this. When the light quantity measuring region 16 is changed, the respective variable resistors 23, 27, 31 and 35 in the photometric region setting pulse circuit 18 shown in FIG. As a result, a light quantity measuring area having a desired size can be set at a desired position of the captured image.

For example, when the door phone using the television camera 38 is installed in the front door 39 as shown in FIG. 6, the subject 1 is shown in FIG. Tends to be skewed to the right. In such a situation, as shown in FIG. 5, the light quantity measuring region 16 is set to the lower side near the right side of the image pick-up screen 14, thereby making it possible to perform metering according to the subject position.

In the above embodiment, a video camera that outputs an image in real time is used. However, a camera may be used to optically photograph a still image or to record on a magnetic disk plate, and the same effects as in the above embodiment are obtained.

As described above, the image capturing apparatus of the present invention can set a desired light quantity measuring area according to the position of the subject, so that it can cope with a camera for various uses.

In addition, since the aperture is adjusted according to the amount of light partially metered in accordance with the position of the subject, the aperture can be automatically adjusted so that the subject is clearly captured even when shooting in backlight.

Claims (2)

The image signal processing unit 5 which processes the signal from the subject and outputs the first signal 102, obtains an average value from the second signal 110, compares the average value with a preset reference value, and automatically adjusts the aperture. Among the third signal 101, which is a composite synchronous signal from the iris control means 6 and the automatic iris control means 6, an arbitrarily designated light amount reference region is set to receive the fourth signal 103 which is a blank pulse. The second signal 110 which is the light quantity information by extracting the light quantity information in the light quantity reference region set by inputting the area setting means 18 and the first signal 102 and the fourth signal 103 as output. ) Has an extraction means 17 for outputting to the automatic iris control mechanism 6, wherein the arbitrarily designated light quantity reference region adjusts the variable resistors 23, 27, 31, 35 in the region setting means 18. The imaging device set by doing. An image pickup apparatus according to claim 1, wherein said area setting means (18) has a horizontal vertical synchronization signal for separating said third signal (101) into a horizontal synchronization signal (104) and a vertical synchronization signal (105).