JPH05122599A - Exposure controller for video camera - Google Patents

Abstract

PURPOSE:To make possible shooting close to human senses by correcting the standard set value of exposure control corresponding to the brightness of an object. CONSTITUTION:After an input signal is detected by a detection circuit 22, the signal is integrated by an integration circuit 30, inputted to an iris driving circuit 32 as an average photometric value and compared with a standard set value for iris, and an iris 12 is controlled. A signal from an AGCAMP 20 is passed through a detection circuit 26, integrated by an integration circuit 34 and compared with a standard set value for AGC, and the gain of the AGCAMP 20 is controlled by an AGC control circuit 36. Further, according to a correcting signal calculating exposure corresponding to the brightness of the object at an exposure calculation circuit 38 based on a signal corresponding to the aperture of the iris and an AGC gain control signal, the standard set values of the iris driving circuit 32 and the AGC control circuit 36 are corrected. Thus, the standard set values are corrected according to brightness, shooting close to the sense of human eyes is enabled.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an exposure control device for a video camera, and more particularly to an exposure control device for a video camera which automatically controls the exposure according to the brightness of a subject.

[0002]

2. Description of the Related Art A conventional exposure control device for a video camera is
The exposure is automatically controlled so that an image with a constant brightness can be obtained regardless of the brightness of the subject. That is, adjust the iris opening according to the brightness of the subject,
The amount of incident light entering the image sensor via the iris is set to the standard setting value, and the signal level of the electric signal converted by the image sensor is set to the standard setting value.
The gain of the C amplifier is adjusted. The exposure control here means control of the amount of light incident on the image sensor, gain control after conversion into an electric signal, and the like.

Further, as a recent exposure control device for video cameras, when the average luminance value of the central portion of the screen is higher than the average luminance value of the peripheral portion, the photometry value for exposure control is calculated by the center-weighted photometry method. When the abnormal light is determined to be present in the central portion of the screen, it has been proposed to correct the exposure control photometric value so that the peripheral portion does not become too dark (Japanese Patent Application No. 1-203580). Specification).

Further, the luminance signal of the subject image is input to the divided photometric circuit through the high luminance clip circuit, the state of the photographing scene is discriminated based on each photometric information from the divided photometric circuit, and the discriminated photographing is conducted. When a scene is a backlight scene, a video camera exposure control device is proposed in which the clip level in the high-luminance clipping circuit is lowered to reduce the influence of backlight in calculating the photometric value (Japanese Patent Laid-Open No. 2-268080). Publication).

[0005]

However, according to the exposure control of the conventional exposure control device for the video camera of this kind, even if the subject is very bright or very dark, the brightness of the preset standard set value is set. Will be photographed.
Therefore, there is a problem that the brightness of the photographed subject is considerably different from that of the subject actually seen by the human eye, which is rather unnatural.

The exposure control device for a video camera disclosed in Japanese Unexamined Patent Publication No. 1-203580 only supports the center-weighted photometry method, and only when the central portion is bright, and when it is extremely dark. Is not considered. In addition, since two types of exposure are switched, one with abnormal light and one without abnormal light, the exposure changes abruptly during switching, resulting in an unnatural image.

On the other hand, in the case of the exposure control device for a video camera disclosed in Japanese Unexamined Patent Publication No. 2-268080, since the clipped luminance signal is used, the luminance cannot be compared normally and the abnormal light is erroneously discriminated. May occur. In order to avoid this, in addition to the clipped luminance signal, it is necessary to measure the non-clipped luminance signal at the same time, which increases the circuit scale.

The present invention has been made in view of the above circumstances, and a bright subject can be photographed relatively brightly, and a dark subject can be photographed relatively darkly, and a photograph closer to the feeling as seen by human eyes is possible. An object is to provide an exposure control device for a video camera. Another object of the present invention is to prevent the ambient light from becoming too dark by reducing the spotlight correction amount for extremely bright abnormal light, and to perform excessive backlight correction when an extremely dark subject is photographed. It is an object of the present invention to provide an exposure control device for a video camera that can prevent the surroundings from becoming too bright.

[0009]

In order to achieve the above object, the present invention provides at least one of the amount of incident light entering the image pickup device from the taking lens through the iris and the signal level of the electric signal converted by the image pickup device. An exposure control device for a video camera that controls one of them to be a standard setting value. A detection unit that detects the brightness of a subject and a brighter unit when the brightness of the subject detected by the detection unit is brighter than usual. And a correction unit that corrects the standard setting value in the direction of shooting and corrects the standard setting value in the direction of shooting dark when the brightness of the subject is darker than usual. still,
The correction means may correct the standard setting value only in a direction in which a bright image is taken or a direction in which a dark image is taken.

Further, a correction means for obtaining an exposure correction amount on the basis of a luminance signal representing a subject image and correcting the standard set value according to the exposure correction amount, a detection means for detecting the brightness of the subject, When the brightness of the subject detected by the detecting means becomes high, the spot light correction amount in the exposure correction amount is reduced, and when the brightness of the subject becomes low, the backlight correction amount in the exposure correction amount is reduced. Means and are provided. The exposure correction amount limiting means may be configured to reduce the correction amount only when the brightness of the subject becomes high or low.

[0011]

According to the present invention, the standard set value for exposure control is corrected according to the brightness of the subject. That is, when the brightness of the subject is brighter than usual, the standard set value is corrected in a direction in which the image is taken brightly, and when the brightness of the subject is darker than usual, the standard set value is corrected in a direction in which the image is taken dark. As a result, a bright subject can be photographed relatively brightly, and a dark subject can be photographed relatively darkly.

According to another aspect of the present invention, an exposure correction amount is obtained based on a luminance signal indicating a subject image, and a standard set value is corrected according to the exposure correction amount, whereby the inside of the subject screen is displayed. When the brightness distribution is in the backlight or spotlight illumination state, the exposure correction is performed so that the central portion of the screen becomes appropriate. The upper limit of the exposure correction amount is limited according to the brightness of the subject, and the correction amount is reduced for extremely bright extraordinary light to prevent the surroundings from becoming too dark. It is also possible to prevent the surroundings from becoming too bright due to excessive backlight compensation when shooting.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of an exposure control device for a video camera according to the present invention will be described in detail below with reference to the accompanying drawings. [First Embodiment] FIG. 1 is a block diagram of a video camera including a first embodiment of an exposure control device for a video camera according to the present invention. An example of application to a video movie camera having an average photometric exposure control device is shown. Shows.

In the figure, the subject light is the photographing lens 10.
Also, an image is formed on the light receiving surface of the image sensor (CCD) 14 via the iris 12. The CCD 14 accumulates incident light as a charge,
The accumulated charge is read in synchronization with the timing pulse applied from the timing generator 16. The electric signal read from the CCD 14 in this way is amplified by the preamplifier 18 and then added to the AGC amplifier 20 and the detection circuit 22.

An AGC gain control signal, which will be described later, is applied to the AGC amplifier 20, and the AGC amplifier 20 amplifies the electric signal with a gain controlled by the AGC gain control signal, and the amplified signal is supplied to the video signal processing circuit 24. And output to the detection circuit 26. The video signal processing circuit 24 includes a white balance circuit, a γ correction circuit, a matrix circuit, an encoder circuit, etc., and after performing predetermined signal processing by these circuits, outputs an NTSC system video signal to the recording device 28, for example. The recording device 28 includes a recording circuit,
Here, after converting the video signal into a recording signal suitable for magnetic recording, the recording signal is magnetically recorded on a recording medium such as a video tape via a magnetic head.

On the other hand, the detection circuit 22 for inputting the electric signal from the preamplifier 18 detects the input signal and integrates it.
Then, the integrating circuit 30 integrates the input signal for one field, and outputs the integrated value to the iris driving circuit 32 as an average photometric value. The iris drive circuit 32 is preset with a standard set value for iris, and the iris drive circuit 32 compares the standard set value for iris with the average photometric value, and the average photometric value is higher than the standard set value for iris. If it is larger, it is judged to be too bright, and the iris 12 is driven in the closing direction. On the other hand, if the average photometric value is smaller than the standard setting value for iris, it is judged to be too dark and the iris 12 is opened. To drive.

Similarly, the detection circuit 26, which receives the electric signal from the AGC amplifier 20, detects the input signal and outputs it to the integration circuit 34. The integration circuit 34 integrates the input signal for one field, and the integrated value. To the AGC control circuit 36. When the AGC standard setting value is preset in the AGC control circuit 36, the AGC control circuit 36 compares the AGC standard setting value with the integral value, and when the integral value is larger than the AGC standard setting value. It is judged that it is too bright, and the gain of the AGC amplifier 20 is reduced.
The gain control signal is output to the AGC amplifier 20, while
When the integrated value is smaller than the standard setting value for AGC, it is judged to be too dark, and the AGC gain control signal is output to the AGC amplifier 20 so as to increase the gain of the AGC amplifier 20.

An exposure correction signal is applied to each of the iris driving circuit 32 and the AGC control circuit 36, and the iris standard setting value and the AGC standard setting value are corrected by the exposure correction signal. That is, a signal corresponding to the opening degree of the iris 12 from the hall element 40 is applied to the exposure calculation circuit 38 via the hall element amplifier 42, and the signal A output from the AGC control circuit 36 is output.
A GC gain control signal has been added. Exposure calculation circuit 3
8 is a signal corresponding to the opening of these iris 12,
The exposure corresponding to the brightness of the subject is calculated from the AGC gain control signal. Note that the smaller the opening of the iris 12, the brighter the subject, and the more the gain by the AGC gain control signal, the darker the subject.

The correction amount calculation circuit 44 calculates the exposure correction amount with respect to the standard setting value from the signal indicating the exposure input from the exposure calculation circuit 38, and outputs the exposure correction signal indicating this correction amount to the iris drive circuit 32 and the AGC control circuit 36. In addition, increase or decrease each standard setting value. The input / output characteristics of the correction amount calculation circuit 44 are as shown in the graph of FIG. 2, for example. In the figure, the maximum value of the correction amount is ± 0.3 EV to ±
The correction amount is 0.5 EV, and the transitional correction amount from the correction amount 0 state to the maximum correction amount gradually changes according to the brightness of the subject.

By correcting the standard setting value according to the brightness of the subject as described above, a bright subject can be photographed relatively brightly, and a dark subject can be photographed relatively darkly, and a photograph closer to the feeling as seen by human eyes can be taken. Will be possible. The first
It is not limited to the case where the standard setting value is corrected both when the brightness of the subject is brighter than normal and when it is dark as in the embodiment, and only one of them may be corrected. [Second Embodiment] FIG. 3 is a block diagram of a video camera including a second embodiment of the exposure control device for a video camera according to the present invention.

In the first embodiment shown in FIG. 1, the standard setting value of the exposure control is corrected according to the brightness of the subject, but in the second embodiment, the abnormal light is adjusted according to the brightness of the subject. The amount of correction for is limited. Incidentally, FIG.
The same parts as those of the first embodiment shown in are denoted by the same reference numerals, and detailed description thereof will be omitted. In FIG.
A low-pass filter (hereinafter referred to as LPF) 100 that receives an electric signal from the preamplifier 18 detects the input signal into a signal indicating a luminance signal. The A / D converter 102 is an LPF
The brightness signal that has passed 100 is converted into a digital signal, and the converted brightness data is output to the screen center integration circuit 104 and the entire screen integration circuit 106.

A window signal indicating the timing at which the window data generating circuit 108 outputs the luminance data of the screen central portion (the range of the broken line in FIG. 4) in one field is added to the screen central portion integrating circuit 104. The center-of-screen integration circuit 104 integrates only the brightness data of the center part of the screen in one field among the brightness data to be input by this window signal, and divides the integrated data by the area within the range of the broken line in FIG. Partial brightness data I ₁
(Microprocessor unit) 110.

Similarly, to the whole screen integration circuit 106, a window signal indicating the timing at which the window signal generation circuit 108 outputs the brightness data of substantially the entire screen (the range indicated by the alternate long and short dash line in FIG. 4) is added. , the entire screen integrating circuit 106 by the window signal, approximately 1 integrated field of luminance data to be input, the entire portion average luminance data I ₂ obtained by dividing the area in the range of one-dot chain line in FIG. 4 and the integrated data to MPU110 Output.

To the other input of the MPU 110, a signal corresponding to the opening degree of the iris 12 from the hall element 40 is passed through the hall element amplifier 42 and the A / D converter 44 to the iris 1
2 is added as the opening degree data and the AGC gain control signal output from the AGC control circuit 36 is A / D.
It is added as AGC gain data via the converter 112.

The MPU 110 inputs the brightness data I ₁ ,
I ₂ , the opening data of the iris 12, and the AGC gain data are processed based on a program stored in a ROM (Read Only Memory) 114 and a look-up table described later, and are processed via the D / A converters 116 and 118. It outputs an exposure correction signal and a drive speed control signal, respectively.

That is, the MPU 110 first obtains the logarithm of the ratio of the central average brightness data I ₁ and the overall average brightness data I ₂ , D = log (I ₁ / I ₂ ). In addition, the opening data of the iris 12 and the AGC
A value obtained by taking the logarithm of the absolute value of the brightness of the subject from the gain data is calculated.

When the absolute value | D | exceeds the threshold Th _D , the exposure correction signal is sent to the D / A converter 116 so that the center-weighted photometry (exposure control mode in which the center of the screen is emphasized) is set. It is output to the iris driving circuit 32 and the AGC control circuit 36 via the iris driving circuit 32. The exposure correction signal limits the exposure correction amount so that it falls within the range of FIG. 5 according to the calculated brightness of the subject. That is, as shown in FIG. 5, when the brightness of the subject is high, the spot light correction amount for the average photometric value is reduced, and when the brightness is low, the backlight correction amount for the average photometric value is reduced.

As a result, when the brightness distribution in the subject screen is in the backlight or spotlight illumination state, the exposure is corrected so that the central portion of the screen becomes appropriate, but the correction amount is adjusted for extremely bright abnormal light. Can be prevented from becoming too bright and the surroundings can also be prevented from becoming too bright due to excessive backlight compensation when an extremely dark subject is photographed.

When the correction amount is reduced as described above
To gradually decrease the correction amount according to the brightness of the subject.
Changes, which results in a natural projection without sudden changes in exposure.
I am trying to get an image. Also, | D | ≦ Th_Dof
In this case, the average metering will be used and the exposure compensation signal will not be the standard value.
It The MPU 110 performs the above exposure compensation and
In the central part, average brightness data I ₁And average brightness data
I₂Are compared before and after the elapse of a predetermined time. And that
Estimate how the shooting scene before and after changed.

That is, as shown in FIG. 6, for the central portion average luminance data I ₁ and the whole portion average luminance data I ₂ , T ₀
The respective values at the time points of I ₁₀ and I ₂₀ , and the values at the time point of T ₁ after ΔT are respectively I ₁₁ and I ₂₁ , and the absolute value symbol is
When expressed by BS, the values of K ₁ = ABS (I ₁₁ −I ₁₀ ) K ₂ = ABS (I ₂₁ −I ₂₀ ) are obtained, and these values are the respective threshold values Th ₁ and Th.
Compared to ₂ . Then, the comparison results are classified as shown in Table 1 below. In the case of | D ₀ |> Th _D , it corresponds to the exposure control by the center-weighted photometry at the time of T _{0.
When 0} | ≦ Th _D , it corresponds to the fact that the exposure control is performed by the average photometry. The table 1 is stored in the ROM 114 as a lookup table.

When these conditions (1) to (3) are actually associated with the shooting scenes before and after ΔT, the conditions: only the background changes, the main subject moves, the shooting scene switching conditions: almost no change Conditions: Only the background changes Conditions: The main subject moves to the center of the screen Conditions: Shooting scene switching conditions: It can be estimated that there is almost no change. It should be noted that the sub-classification in the conditions, _{"| D 1 |> | D 0} | " In conditions A, "| D ₁ |
> | D ₀ | ”is the condition B, and the condition A is assumed to be, for example, a scene in which the main subject has moved to the center of the screen.

After performing the above-described arithmetic processing, the MPU 110 estimates the state of the shooting scene before and after the ΔT time and changes the operation speed of the exposure / gain control. That is, the operation speed of the iris 12 and the AGC amplifier 20 becomes slower when the shooting scene is determined to be the condition B, and the iris 12 and the AGC are set when the shooting scene is determined to be the condition A. Amplifier 2
The drive speed control signals are respectively sent via the D / A converter 118 so that the operating speed of 0 becomes faster.
And to the AGC control circuit 36. Incidentally, the drive speed control signal is a control signal such as how many EVs can be moved per second. For example, when the speed is 10 EV / sec, the operation speed is fast, and when it is 0.5 EV / sec. The operation speed is slow.

The operation of the video camera exposure control device configured as described above will be described with reference to the flowchart shown in FIG. The exposure / gain control is started by the start of recording, and at the same time, the central portion average luminance data I ₁ and the whole portion average luminance data I ₂ are divided and metered. Then, exposure / gain control by average photometry is first performed on the basis of the overall average brightness data I ₂ . In this case, the MPU 110 does not output the exposure correction signal, and therefore the total amount of light received by the CCD 14 is adjusted to be constant. Further, in this case, a high speed signal is output from the MPU 110 as a drive speed control signal. As described above, the exposure / gain adjustment is instantaneously performed in the average photometry mode at the start of recording, whereby it is possible to prevent the exposure amount of the main subject from deviating extremely from the proper value.

The value of D is subsequently calculated and compared with the value of Th _D. When “| D |> Th _D ”, the central part average luminance data I ₁ and the whole part average luminance data I ₂ are in a state of being greatly different, and the probability that the main subject is located in the central part of the screen is high. In consideration of this, when the exposure control is performed in the average photometry mode as it is, the exposure amount of the main subject is often incorrect. Therefore, "| D |>
When it is determined to be “Th _D ”, a flag F _C indicating that the mode is shifted to the center-weighted photometry mode is set, and
The exposure compensation signal corresponding to the central average brightness data I ₁ is MP
The drive speed control signal output from U110 via the D / A converter 116 and increasing the operation speed is MPU110.
Is output via the D / A converter 118. In addition, "|
When D | ≦ Th _D ”, the average photometry mode is maintained as it is.

After the exposure / gain control is performed in this way,
After ΔT, the divided photometry is performed again, and the central average brightness data I ₁₀ and the entire average brightness data I ₂₀ obtained by the previous divided photometry are added to the new central average brightness as shown in FIG. The data I ₁₁ and the whole-part average luminance data I ₂₁ are detected. Then, from the absolute value of the difference of each luminance data, K
The values of ₁ and K ₂ are determined. The values of K ₁ and K ₂ are compared with the respective thresholds Th ₁ and Th ₂ and classified according to Table 1 above. In addition, the ΔT time is set to CCD1
It is also possible to match 4 with the field read cycle, and in this case, it is not necessary to separately provide a timer for measuring ΔT.

When the values of K ₁ and K ₂ are obtained in this way,
The state of the shooting scene is estimated before and after the elapse of ΔT time. In the center-weighted photometry mode, when the condition, that is, the center average brightness data I ₁ and the whole part average brightness data I ₂ both greatly change, the shooting scene is switched by, for example, panning the video camera greatly. Since it can be estimated that this is the case, after releasing the center-weighted metering mode, the exposure / gain control is restarted in the average metering mode for a new scene.

Further, when only the central part average brightness data I ₁ largely changes and the whole part average brightness data I ₂ does not change much, and | D ₁ |> | D ₀ | It is a scene in which the main subject has moved to the center of the screen at that time. In this case, the exposure / gain control is performed at high speed based on the center average brightness data I ₁₁ newly detected in the center-weighted metering mode. Let's do it in. still,
Central part average brightness data I ₁ , whole part average brightness data I ₂
If there is almost no change in both, it means that the same scene with similar brightness distribution is being continuously shot, so the center-weighted metering mode is continued and exposure and gain control are performed at high speed. You can leave it alone.

In the case other than the condition A and the condition under the center-weighted photometry mode or the condition under the average photometry mode, the main subject is moving in the subject screen shown in FIG. By panning the video camera in accordance with the movement of the subject, it is estimated that only the brightness changes in the background. In such a case, the MPU 110 outputs, via the D / A converter 118, a drive speed control signal that slows down the operation speed of the exposure / gain control. As a result, both the iris drive circuit 32 and the AGC control circuit 36 operate slowly, and the exposure amount of the main subject does not change rapidly.

When continuity is recognized in the photographic scene as described above, the operation speed of the exposure / gain control is slowed down rather than the exposure / gain control is performed at high speed by following the change in the brightness of the background. The exposure amount is stabilized.
Of course, the background depiction is sacrificed to some extent by performing such control, but in a continuous scene, it is better to keep the exposure of the main subject stable, so that an image with a natural feeling can be obtained during image reproduction.

The determination of the continuity of the photographed scene is not limited to the above embodiment, but the determination can be made based on the spatial frequency component in the luminance signal. For example, BFP with when focusing is performed, the pass bandwidth of the 600KH _Z ~2.4MH _Z is a spatial frequency component having the general subject
(Band pass filter) as shown in FIG.
Is used instead of
The continuity of the shooting scene can be determined based on the output data of No. 4. That is, the autofocus device mounted on the video camera has an area near the area surrounded by the broken line in the center of the screen shown in FIG. 4 as a distance measuring area, and the taking lens 10 focuses on this area. Is going. Since the BPF passes through a spatial frequency component that increases during focusing, the output data from the screen center integration circuit 104 is the integral value of the spatial frequency component in the focused area.

As described above, the integrated values of the spatial frequency components are compared before and after the ΔT time, and when there is a large change, it can be estimated that the object to be measured, that is, the main subject has changed. Therefore, in this case, the operation speed of the exposure / gain control may be increased, and the operation speed of the exposure / gain control may be decreased when the integrated value of the spatial frequency component does not change much.

If the angle of view of the taking lens 10 is θ, the size of the main subject in one direction in the subject screen is L, and the distance to the main embodiment is X, then L∝1 / (tan θ · X ) Have a relationship. Therefore, ΔT
It is possible to presume that the scene has been switched when the comparison is made before and after the time and the change exceeds the predetermined range.

Even if the video camera itself maintains the same posture, the brightness distribution on the screen may change significantly due to zooming. In such a case, it is natural to assume that the scenes have been virtually switched,
It is recommended to increase the exposure / gain control operation speed. In this case, the scene switching determination can be made by detecting the temporal change amount of the zoom position of the taking lens 10.

In the second embodiment, the exposure correction amount is set to be small when the brightness of the subject becomes high and low, but the present invention is not limited to this, and when the brightness of the subject becomes high. Only the exposure correction amount may be reduced, or the exposure correction amount may be reduced only when the brightness of the subject becomes low. The exposure control device for a video camera according to the present invention can be applied not only to a video movie camera but also to an electronic still video camera.

[0045]

As described above, according to the exposure control device for a video camera of the present invention, the standard set value which is the target of the exposure control is corrected by the brightness of the subject, so that the bright subject is relatively bright. A bright or dark subject can be photographed relatively darkly, which makes it possible to photograph a subject closer to what the human eye perceives.

Further, when the brightness distribution in the subject screen is in the backlight or spotlight illumination state, the exposure correction is performed so that the central portion of the screen becomes appropriate, but when the brightness of the subject becomes high, the exposure correction amount When the spot light correction amount is reduced and the brightness of the subject becomes low, the backlight correction amount in the exposure correction amount is reduced, so the correction amount is reduced for extremely bright abnormal light and the surroundings become dark. It is also possible to prevent the surroundings from becoming too bright due to excessive backlight compensation when an extremely dark subject is photographed. Furthermore, when the correction amount is reduced as described above, the correction amount is changed so as to be gradually decreased according to the brightness of the subject, and thereby a natural image without a sudden change in exposure can be obtained. Further, since only absolute brightness is used for correction for abnormal light, there is an advantage that it does not depend on the photometric pattern or the priority position, and is not affected by the clip level of the high brightness clip circuit.

[Brief description of drawings]

FIG. 1 is a block diagram of a video camera including a first embodiment of an exposure control device for a video camera according to the present invention.

FIG. 2 is a graph showing an example of a correction amount of a standard setting value with respect to the brightness of a subject.

FIG. 3 is a block diagram of a video camera including a second embodiment of an exposure control device for a video camera according to the present invention.

FIG. 4 is an explanatory diagram showing an example of a subject screen.

FIG. 5 is a graph showing a range of an exposure correction amount with respect to the brightness of a subject.

FIG. 6 is a graph showing an example of variations in photometric values in each photometric region.

FIG. 7 is a flow chart used to explain the operation of the embodiment shown in FIG.

[Explanation of symbols]

 10 ... Photographing lens 12 ... Iris 14 ... Imaging device (CCD) 18 ... Preamplifier 20 ... AGC amplifier 22, 26 ... Detection circuit 24 ... Video signal processing circuit 30, 34 ... Integration circuit 32 ... Iris drive circuit 36 ... AGC Control circuit 38 ... Exposure calculation circuit 40 ... Hall element 44 ... Correction amount calculation circuit 100 ... LPF 104 ... Screen central part integration circuit 106 ... Whole screen integration circuit 108 ... Window signal generation circuit 110 ... MPU

Claims (6)

[Claims] 1. An exposure for a video camera, which controls so that at least one of an incident light amount incident on an image pickup device from a taking lens through an iris and a signal level of an electric signal converted by the image pickup device has a standard set value. In the control device, a detection unit that detects the brightness of the subject, and a correction unit that corrects the standard setting value in a direction to make the image brighter when the brightness of the subject detected by the detection unit is brighter than usual, An exposure control device for a video camera, comprising: 2. An exposure for a video camera, which controls so that at least one of an incident light amount incident on an image pickup device from a taking lens through an iris and a signal level of an electric signal converted by the image pickup device becomes a standard set value. In the control device, a detection unit that detects the brightness of the subject, and a correction unit that corrects the standard setting value in a direction in which the brightness of the subject detected by the detection unit is darker than usual, in a direction in which the image is captured darkly. An exposure control device for a video camera, comprising: 3. An exposure for a video camera, which controls so that at least one of an incident light amount incident on an image pickup device from a taking lens through an iris and a signal level of an electric signal converted by the image pickup device has a standard set value. In the control device, detecting means for detecting the brightness of the subject, and when the brightness of the subject detected by the detecting means is brighter than usual, the standard setting value is corrected in a direction to make the subject brighter and An exposure control device for a video camera, comprising: a correction unit that corrects the standard setting value in a direction in which the image is taken darker when the brightness is darker than usual. 4. An exposure for a video camera, which controls so that at least one of an incident light amount incident on an image sensor from a photographing lens through an iris and a signal level of an electric signal converted by the image sensor has a standard set value. In the control device, a correction unit that obtains an exposure correction amount based on a luminance signal indicating a subject image and corrects the standard setting value according to the exposure correction amount; a detection unit that detects the brightness of the subject; An exposure control device for a video camera, comprising: exposure correction amount limiting means for reducing the spot light correction amount in the exposure correction amount when the brightness of the subject detected by the means increases. 5. An exposure for a video camera, which controls so that at least one of an incident light amount incident on an image sensor from a photographing lens through an iris and a signal level of an electric signal converted by the image sensor has a standard set value. In the control device, a correction unit that obtains an exposure correction amount based on a luminance signal indicating a subject image and corrects the standard setting value according to the exposure correction amount; a detection unit that detects the brightness of the subject; An exposure control device for a video camera, comprising: an exposure correction amount limiting device that reduces a backlight correction amount in the exposure correction amount when the brightness of the subject detected by the device becomes low. 6. An exposure for a video camera, which controls so that at least one of an amount of incident light entering an image pickup device from a taking lens through an iris and a signal level of an electric signal converted by the image pickup device has a standard set value. In the control device, a correction unit that obtains an exposure correction amount based on a luminance signal indicating a subject image and corrects the standard setting value according to the exposure correction amount; a detection unit that detects the brightness of the subject; When the brightness of the subject detected by the means is increased, the spot light correction amount in the exposure correction amount is decreased, and when the brightness of the subject is decreased, the backlight correction amount in the exposure correction amount is decreased. And an exposure control device for a video camera.