JP2002223388A - Device and method for controlling iris and television camera - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a wide and dynamic range video signal with an enhanced hierarchical reproduction ability in a wide dynamic range television camera which uses an auto-iris lens for inputting video signal and controlling an iris. SOLUTION: A long-time exposure video signal component between long-time and short-time exposure video signals which are outputted from a solid-state imaging device by time division is divided into optional areas. The area with the minimum luminance level is detected from the divided areas and the long- time exposure video signal of the area except the detected area is weighted to reduce a signal level. Then the iris of the auto-iris lens is controlled in accordance with the weighted long-time exposure video signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a television camera for obtaining a video signal having a wider dynamic range, and more particularly, to a diaphragm of an auto iris lens for condensing imaging light in accordance with a captured video signal. The present invention relates to an apparatus and a method for controlling the aperture of a television camera for controlling the camera, and a television camera using the same.

[0002]

2. Description of the Related Art Conventionally, a long-time exposure video signal (long-exposure video signal) obtained by photoelectrically converting long-time exposure imaging light and a short-time exposure signal obtained by photoelectrically converting the short-time exposure imaging light. There is a television camera that obtains a video signal with a wide dynamic range by using a solid-state imaging device that can output an exposure video signal (short exposure video signal) in a time-division manner. As a lens with an automatic iris control used in this television camera, that is, an auto iris lens, a DC voltage control method, for example, a galvanometer type auto iris lens is realized.

FIG. 1 shows a configuration of a conventional wide dynamic television camera in the case where an auto iris lens of a type in which an aperture is controlled by inputting a video signal is used.
The conventional technology will be described with reference to FIG. In this figure, the image pickup light from the subject is
And is incident on a solid-state imaging device (CCD) 18.
The CCD 18 is, for example, a short-time exposure video signal obtained by exposing the imaging light for 1/2000 seconds, and exposing the imaging light for a time longer than that of the short-time exposure video signal, for example, about 1/60 second. And the long-time exposure video signal obtained as a result. Here, for example, a long-exposure video signal for one horizontal scan and a short-exposure video signal for one horizontal scan are output within one horizontal scan period.
The video signal output from the CCD 18 is sampled and held by a CDS (correlated double sampling) circuit 19, and the sampled and held signal is automatically gained by an AGC (automatic gain control) circuit 20 so that the signal has a predetermined level. Controlled. Further, the video signal subjected to the automatic gain control is converted from an analog video signal into a digital video signal by the A / D converter 21.

[0006] The video signal sampled and held by the CDS circuit 19 is further input to an auto iris lens 17 as an iris control signal.
Reference numeral 7 performs aperture control according to the input iris control signal.

On the other hand, the digital video signal output from the A / D converter 21 is input to a synchronization circuit 22, where it is separated into a long-exposure video signal and a short-exposure video signal. Each signal is lengthened in time. The time-expanded long-exposure video signal and the short-exposure video signal are synchronized so that they are simultaneously output.

[0006] The long-time exposure video signal synchronized by the synchronization circuit 22 is input to a synthesizing circuit 31, where these signals are synthesized, and the synthesized video signal is input to a video signal processing circuit 32. You. The video signal processing circuit 32
The input video signal is subjected to predetermined video signal processing, for example, gamma correction, enhancer processing, white balance processing, and the like, and output to a subsequent stage (not shown).

[0007] The microcomputer (CPU) 33
It controls the operations of the AGC circuit 20, the video signal processing circuit 32, and the synthesizing circuit 31, and performs, for example, automatic gain control processing.
Built-in software for controlling white balance processing, synthesis processing, etc.

On the other hand, a television camera configured as shown in FIG. 2 has been proposed by the present applicant. In the configuration of FIG. 2, a long-exposure video signal synchronized by the synchronization circuit 22 is a long exposure video signal. Similarly, the short-time exposure video signal is input to the short-exposure video signal processing circuit 24. The long-exposure video signal processing circuit 23 and the short-exposure video signal processing circuit 24 perform predetermined video signal processing on the input video signals, respectively.
For example, gamma correction, enhancer processing, white balance processing, and the like are performed.

The long-exposure video signal and the short-exposure video signal which have been subjected to predetermined video signal processing by the long-exposure video signal processing circuit 23 and the short-exposure video signal processing circuit 24 are both synthesized and processed. Input to a tone correction processing circuit 25, where they are combined using a combining method for expanding the dynamic range of the video signal, and the combined video signal is subjected to gradation correction processing to obtain a wide dynamic range. It becomes a video signal. Then, the wide dynamic range video signal is output to a subsequent stage (not shown).

The microcomputer (CPU) 26 comprises:
The AGC circuit 20 controls the operations of the AGC circuit 20, the long exposure video signal processing circuit 23, the short exposure video signal processing circuit 24, and the synthesizing / gradation correction processing circuit 25. For example, automatic gain control processing, white balance processing, and synthesizing processing It has software for performing such controls.

[0011]

Here, an auto iris lens of a television camera for obtaining a video signal of a wide dynamic range using a solid-state imaging device capable of time-divisionally outputting a long-exposure video signal and a short-exposure video signal. It is conceivable to perform aperture control according to a low-luminance area of a subject to be imaged. For example, as illustrated in FIG. 4, a subject in a low-luminance area (for example, a dark indoor where a person under fluorescent lighting is present) indicated by a halftone area and a high-luminance area (an area without halftone dots) For example, a case will be described in which an image of a brighter subject under sunlight is captured. In this case, as a synthesizing method for expanding the dynamic range of the video signal in the synthesizing circuit 31 and the synthesizing / gradation correction processing circuit 25, for example, a long-exposure video signal is selected for a low luminance area, For the high luminance area, short-time exposure video signals are selected, and these selected video signals are synthesized.

By the way, if the aperture value of the auto iris lens of the television camera is controlled so as to be suitable only for the indoor subject, the video signal output from the CCD 18 may be used for a long time under indoor exposure conditions. By controlling the exposure time for the short-exposure video signal at the same time as obtaining the exposure video signal, a short-exposure video signal with exposure conditions is output almost outdoors. Then, when these signals are combined, a wide dynamic range video signal in which gradations are similarly well reproduced for indoor and outdoor subjects can be obtained.

However, in the case of the configurations shown in FIGS. 1 and 2, the iris control signal for controlling the aperture of the auto iris lens 17 is created based on a signal in which a long exposure video signal and a short exposure video signal are mixed. ing. With the iris control signal generated based on such mixed signals, it becomes impossible to control the aperture so as to suit only the indoor subject. Therefore, in the case where such an iris control signal is subjected to average detection processing inside the auto iris lens, if an image of a subject as shown in FIG. 4 is taken, the aperture value is set to be more suitable for a subject outdoors (high-luminance area). Value.

At this time, as an output video signal after the synthesis, an object in the outdoors (high luminance area) has a higher tone reproduction, while a subject in the indoor (low luminance area) is blackened. There is a danger that a video signal that has caused the blackout may be obtained. Therefore, if the video signal has a blackout condition, there is a disadvantage that an appropriate wide dynamic range video signal cannot be obtained.

It is an object of the present invention to obviate this disadvantage.
An object of the present invention is to provide an aperture control device and method for a television camera and a television camera using the same. Another object of the present invention is to use an auto iris lens for performing iris control based on a signal obtained by performing an average detection process on an input video signal, and to use the indoor (low luminance area) subject and the outdoor (high luminance area) as described above. Even at the time of imaging in which the subject is mixed and imaged, control is performed such that the aperture control of the auto iris lens is more suitable for the low luminance area,
Provided are an aperture control device and method for a television camera capable of obtaining a wide dynamic range video signal that enables good gradation reproduction of both indoor and outdoor subjects, and a television camera using the same. That is.

[0016]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, an object of the present invention is to provide a diaphragm control device for a television camera, comprising: a long-exposure video signal obtained from imaging light for exposing a subject for a long time; A solid-state image sensor for time-divisionally outputting a short-exposure video signal obtained from imaging light for short-time exposure, a dividing unit for dividing an imaging screen of the long-exposure video signal into a plurality of predetermined regions, A detection unit that detects a first region and a second region having different luminance levels, and a weighting unit that applies different weights to the long-exposure video signals of the first region and the second region, respectively. A control unit that controls a diaphragm of a lens through which imaging light supplied to the solid-state imaging device passes according to the weighted long exposure video signal.

In the present invention, the first area may be an area in which the average luminance level of the long exposure video signal is minimum, and the weighting unit may be configured to output the video signal of the long exposure video signal in the second area. Weighting to decrease the level may be applied. Further, the weighting unit may perform predetermined weighting such that a reduction rate of a level of the long exposure video signal of the first region is larger than a long exposure video signal of the second region. The weighted long exposure video signal may be supplied to the lens in synchronization with the video signal from the solid-state imaging device.

According to another aspect of the present invention, there is provided a television camera, comprising: a lens unit having an aperture; and imaging light from a subject being given through the lens to expose the subject for a long time. A solid-state image sensor that outputs a long-exposure video signal obtained from imaging light and a long-exposure video signal obtained from imaging light that exposes the subject for a short time in a time-division manner; A detector for detecting a first area and a second area having different luminance levels of the long exposure video signal, and a long exposure video for the first area and the second area, respectively. A weighting unit for applying different weights to the signals, a combining unit for combining the long exposure video signal and the short exposure video signal, and a diaphragm for the lens according to the weighted long exposure video signal. In which a control unit for controlling.

In the present invention, the weighting section may further perform weighting to reduce a video signal level of a long exposure video signal of the second area, and the combining section may apply a weight to the first area. The long exposure video signal may be selected, the short exposure video signal may be selected for the second region, and the long exposure video signal and the short exposure video signal may be combined. .

According to another aspect of the present invention, there is provided an aperture control method for a television camera.
A long-exposure video signal obtained from the imaging light for exposing the subject for a long time and a long-exposure video signal obtained from the imaging light for short-time exposure of the subject are output in a time-division manner. Dividing into a plurality of regions, detecting a first region and a second region having different luminance levels of the long exposure video signal, and detecting the first region and the second region with respect to the long exposure video signal. Different weights are applied, and the aperture of the lens through which the imaging light supplied to the solid-state imaging device of the television camera passes is controlled in accordance with the weighted long exposure video signal.

Further, according to the present invention, the luminance level of the long exposure video signal in the first area may be minimum.
Further, the weighting step may further reduce a video signal level of the long exposure video signal of the second area, and the weighting step may include a long exposure video signal of the second area. The predetermined weighting may be performed so that the rate of decrease in the level of the long-exposure video signal in the first area is greater than that in the first area.

In the present invention, the step of controlling the aperture may supply the weighted long-exposure video signal to the lens in synchronization with a video signal from the solid-state imaging device. .

According to another aspect of the present invention, a long-exposure video signal obtained by photoelectrically converting imaging light subjected to long exposure and a photoelectric conversion of the imaging light subjected to short exposure are provided. A television camera comprising: a solid-state imaging device that outputs the obtained short-time exposure video signal in a time-division manner; and a control unit that controls a diaphragm of a lens that focuses the imaging light in accordance with the video signal. Means for dividing the exposure video signal for each of a plurality of predetermined areas; means for detecting a first area of the plurality of areas in which the luminance level of the long-time exposure video signal is minimum; Means for applying a predetermined weight to the long-time exposure video signal in the area (a), wherein the control means controls the aperture of the lens according to the weighted long-time exposure video signal.

Further, in the present invention, the luminance level may be an average luminance level of a long-time exposure video signal of the divided area.

Further, in the present invention, the weighting means may be arranged so that the gain of the first area is lower than the gain of the video signal level of the detected area. A predetermined weight may be applied to the long-time exposure video signal in the outer region.

According to the present invention configured as described above, two subjects having different luminance level differences, such as a mixture of an indoor (low luminance region) subject and an outdoor (high luminance region) subject, are simultaneously imaged. However, since it is possible to control the auto iris so that the aperture control of the auto iris diagram matches the low brightness area, it is possible to realize a television camera that has a wide dynamic range video signal with gradation reproduction capability indoors and outdoors. it can.

[0027]

An embodiment of the present invention will be described below with reference to FIG. In this figure, imaging light from a subject is condensed by an auto iris lens 1 and is incident on a solid-state imaging device (CCD) 2. For example, the CCD 2 exposes the short-time exposure video signal obtained by exposing the imaging light for 1/2000 second and the imaging light for about 1/60 second longer than the case of the short-time exposure video signal. And the long-time exposure video signal obtained as a result. here,
For example, within one horizontal scanning period, a time-compressed long exposure video signal for one horizontal scan and a short exposure video signal for one horizontal scan are output. The video signal output from the CCD 2 is sampled and held by the CDS circuit 3, and the sampled and held signal is subjected to automatic gain control by the AGC circuit 4 so that the signal has a predetermined level.
Further, the video signal subjected to the automatic gain control is supplied to the A / D converter 5.
Is converted from an analog video signal to a digital video signal.

The digital video signal output from the A / D converter 5 is input to a synchronization circuit 6, where it is separated into a long-exposure video signal and a short-exposure video signal. Are respectively time-expanded. The time-expanded long-exposure video signal and the short-exposure video signal are synchronized so that they are simultaneously output.

The long exposure video signal synchronized by the synchronization circuit 6 is input to the long exposure video signal processing circuit 7, while the short exposure video signal also synchronized by the synchronization circuit 6 is short exposure video signal. To the video signal processing circuit 8. The long-exposure video signal processing circuit 7 and the short-exposure video signal processing circuit 8 perform predetermined video signal processing on the input video signals, for example, perform gamma correction, enhancer processing, white balance processing, and the like. .

The long-exposure video signal and the short-exposure video signal which have been subjected to predetermined video signal processing by the long-exposure video signal processing circuit 7 and the short-exposure video signal processing circuit 8, respectively, are combined and processed. Input to the tone correction processing circuit 9,
Therefore, they are combined, and the combined video signal is subjected to gradation correction processing to become a wide dynamic range video signal. The synthesis / gradation correction processing circuit 9 selects a long-exposure video signal for a low-luminance area of the subject to be imaged, and selects a short-exposure video signal for a high-luminance area. A long-time and short-time exposure video signal is synthesized. As a method of synthesizing such a video signal, for example, Japanese Patent Application No. 11-15979 filed by the present applicant has been proposed.
The method disclosed in Japanese Patent Laid-Open No. 1 may be used. And
The wide dynamic range video signal thus synthesized is output to a subsequent stage (not shown).

The microcomputer (CPU) 10 is A
It controls the operations of the GC circuit 4, the long exposure video signal processing circuit 7, the short exposure video signal processing circuit 8, and the synthesis / gradation correction processing circuit 9. For example, an automatic gain control process,
Software for controlling white balance processing, synthesis processing, and the like is built in, and a control signal for performing the above-described control is output in accordance with processing by the software.

The video signal output from the CCD 2 is input to the CDS circuit 3 as described above, and is further input to the CDS circuit 11 for generating an iris control signal for controlling the aperture of the auto iris lens 1. The video signal input to the CDS circuit 11 is sampled and held there, and is converted from an analog video signal to a digital video signal by the A / D converter 12.

In this television camera, the CPU 10 determines that the long exposure video signal from the long exposure video signal processing circuit 7 is lower than the predetermined level when an image of a dark subject having a predetermined brightness level or less is picked up. When detected,
The CPU 10 does not perform signal amplification by automatic gain control on the video signal input to the CDS circuit 11 and sampled and held. As a result, the aperture of the auto iris lens 1 can be kept open. By doing so, when capturing a dark subject having a brightness level equal to or less than a predetermined luminance level, the aperture control of the auto iris lens 1 and the hunting by the automatic gain control, which may occur when the signal is amplified by the automatic gain control. The operation is prevented from occurring by not performing the automatic gain control described above.

The digital video signal from the A / D converter 12 is input to the synchronization circuit 13, where the long-exposure video signal is separated and time-expanded to a signal of one horizontal scanning period. Further, a long-exposure video signal that is extended for the time is output. The long-time exposure video signal output from the synchronization circuit 13 may be output in synchronization with the video signal output from the synchronization circuit 6 described above.

The long-time exposure video signal output from the synchronization circuit 13 is input to the weighting circuit 14. In the weighting circuit 14, the details of the operation will be described later, but different weights are applied to the portion corresponding to the high-brightness region of the subject to be imaged and the portion corresponding to the low-brightness region of the subject of the input long-exposure video signal. By doing so, the signal level of the long exposure video signal is corrected. The long-time exposure video signal whose signal level has been corrected by the weighting circuit 14 is D
The digital video signal is converted into an analog video signal by the / A converter 15 and output as an iris control signal for controlling the auto iris lens 1. The iris of the auto iris lens 1 is controlled by the iris control signal.
It should be noted that the reason why the iris control signal is generated based on the long-exposure video signal instead of the short-exposure video signal is that the iris control signal is generated based on the long-exposure video signal in order to further suppress the video signal level in the high luminance area of the subject. This is because the gradation reproducibility can be further improved for the objects in the high luminance and low luminance regions.

Here, the operation of the weighting circuit 14 and the control of the operation by the CPU 10 will be described in detail. First, the long-exposure video signal output from the synchronization circuit 6 is input to the long-exposure video signal processing circuit 7 and also to the region division processing circuit 16. In the area division processing circuit 16, the imaging screen is divided into a plurality of predetermined areas,
The average luminance value data of all the video signals corresponding to each of the divided areas is calculated. In the present embodiment, it is assumed that the image data is divided into five regions and processed as shown in an example in FIG. As a method for dividing the imaging screen, it is sufficient to divide the image into three or more regions, and preferably, into four or more regions.

The calculated average luminance value data for each area is input to the CPU 10. FIG. 8 is a flowchart illustrating an example of a processing operation by the CPU 10. CPU
At 10, the average luminance value data of the five regions from the region division processing circuit 16 is fetched (step 100), and the region having the lowest average luminance value data among the five regions, that is, the darkest average luminance A value area (hereinafter, referred to as a low luminance area) is detected (step 101). Based on the detection result, the CPU 10 performs synchronization so that the video signal levels of all other areas (hereinafter, referred to as high-luminance areas) except the detected darkest area become lower than the current level. A parameter or weighting signal W for weighting the long-time exposure video signal output from the conversion circuit 13;
Output to the weighting circuit 14 (step 102).

Here, the weighting of the long-time exposure video signal corresponding to the high-luminance area is such that the average luminance value of the video signal in the high-luminance area is substantially the same as the average luminance value of the video signal in the low-luminance area (the second luminance value). (1 desired value). Alternatively, if the subject in the low-luminance area does not cause blackout, the average luminance value of the video signal in the high-luminance area is slightly larger than the average luminance value of the video signal in the low-luminance area (second
(A desired value) may be set.

Alternatively, the low-luminance area and the high-luminance long-time exposure video signal are so adjusted that the reduction rate of the video signal level in the high-luminance area is greater than the reduction rate of the video signal level in the low-luminance area. A predetermined weight may be applied.

The setting of the weighting (that is, the setting value of the parameter or the weighting signal W) is performed gradually so that the average luminance value of the video signal in the high luminance area becomes the first or second desired value. You may control it. Alternatively, a memory (for example, RAM) in the CPU 10
A table corresponding to the first or second desired value according to the average luminance value of the video signal in the high luminance area and the average luminance value of the video signal in the low luminance area, The level of the weighting signal W is written in advance, and the level of the parameter or the weighting signal is read and output according to the average luminance value of the video signal in the high luminance area and the average luminance value of the video signal in the low luminance area. May be. The above steps 101 to 103 may be performed for each frame of the video signal, or may be performed for a plurality of frames.

A parameter or a weighting signal W for performing such weighting is output from the CPU 10 to the weighting circuit 14. In the weighting circuit 14,
The parameter or weighting signal W is input, and the long exposure video signal input from the synchronization circuit 13 in accordance with the input parameter or weighting signal W corresponds to the portion corresponding to the high volatility region of the subject to be imaged. An iris control signal corrected so that the video signal level in the high-brightness area is reduced from the current level by performing different weighting on the portion corresponding to the low-brightness area of the subject.

Hereinafter, a method of correcting the video signal signal level will be described with reference to FIGS. 4, 5, 6, and 7. FIG.
Here, the case where the weight signal W is output from the CPU 10 will be described, and a specific example of the weight signal W will be described.

In the example of FIG. 4, the high luminance area is the area 3 of FIG.
, And the low-luminance area corresponds to the other distributions 1, 2, 4, 5 in FIG.
Corresponding to Therefore, different weights are applied to the portion corresponding to the region 3 and the portions corresponding to the regions 1, 2, 4, and 5 of the long-exposure video signal, and specifically, the video signal level of the region 3 becomes higher than the current level. Weighting is performed so as to decrease. Therefore, in FIG. 5, the vertical scanning area Va1 includes the distribution areas 2 and 3, and the horizontal scanning line L1 of the area Va1 is included.
As shown in FIG. 6A, the weighting signal W1 corresponding to the region 2 has a different level between the portion corresponding to the region 2 and the portion corresponding to the region 3; The portion corresponding to 3 is set to a high level. Similarly, in the vertical scanning area Va2, the areas 1, 2, 2
3 and the horizontal scanning line L2 in the area Va2.
As shown in FIG. 6B, the weighting signal W2 corresponding to the area 2 and the area 1 has a low level, and the area corresponding to the area 3 has a high level. On the other hand, in the vertical scanning areas Va3 and Va4,
, And regions 1, 4, 5 and 4,
5 only. Therefore, the vertical scanning area Va3
And the weighting signals W3 and W4 corresponding to the horizontal scanning lines L3 and L4 in Va4 are all set to the low level as shown in FIG.

These weighting signals are supplied to the synchronization circuit 13
Are output in synchronization with the long-time exposure video signal output from.

FIG. 7 shows each vertical scanning area Va1 to Va4.
5 is a diagram showing a correspondence relationship between signal levels of weighting signals W1 to W4 and a signal level of an iris control signal in FIG.

FIGS. 7A and 7B show the weighting signal W1 and the signal W1 in the vertical scanning area Va1, respectively.
5 shows a waveform of the iris control signal I1 weighted according to the following equation. In FIG. 7B, the waveform of the unweighted iris control signal (the long-time exposure video signal output from the synchronization circuit 13) represented by the solid line 100 has the darkest average luminance value of the signal level. Region (low-luminance region) A (FIG. 5)
Region 2) and a region (high-luminance region) B (corresponding to region 3 in FIG. 5) other than that region. As described above, in this example, the area A corresponds to a low-luminance area where an indoor subject is photographed, and the area B corresponds to a high-luminance area where an outdoor subject is photographed.

Here, the level of the iris control signal is controlled in accordance with the level of the weighting signal W1 as described above. Specifically, while the weighting signal W1 is at the low level (corresponding to the area 2 in FIG. 5), the level of the iris control signal in the area A is not changed correspondingly, but while the weighting signal W1 is at the high level (see FIG. 5). 5 (corresponding to region 3), the level of the iris control signal in region B is correspondingly reduced from the current level, resulting in a waveform as indicated by a dotted line 101.

The weighted iris control signal waveform represented by the dotted line 101 obtained by performing the weighting process is compared with the signal level of the region B indicated by the solid line 100 in the region B ′ indicated by the dotted line 101. The average luminance value of the signal level is made smaller. The iris control signal I1 thus obtained is output from the CCD 2, for example,
It is output from the D / A converter 15 and given to the lens 1 at such a timing as to control the lens 1 in synchronization with the video signal of the next frame (or a frame after a plurality of frames).

FIGS. 7C and 7D show the weighting signal W2 and the signal W2 in the vertical scanning area Va2, respectively.
Shows the waveform of the iris control signal I2 weighted according to While the weighting signal W2 is at the low level (corresponding to the areas 2 and 1 in FIG. 5), the level of the iris control signal I2 in the area C is not changed correspondingly, but while the weighting signal W2 is at the high level (FIG. (Corresponding to the area 3 of FIG. 3)), the level of the iris control signal I2 in the area D is reduced from the current level, and the waveform becomes as shown by the dotted line 103. Note that a solid line 102 shows an iris control signal waveform before weighting.

FIGS. 7E and 7F show the weighting signal W3 and the signal W3 in the overlapping direct scanning area Va3, respectively.
Shows the waveform of the iris control signal I3 weighted according to The weighting signal W3 remains at the low level as a whole (corresponding to the regions 4, 1, and 5 in FIG. 5), and the level of the iris control signal I3 in the entire region E is not changed correspondingly. Accordingly, the levels of the iris control signal I3 before and after the weighting have the same waveform as shown by the solid line 104 and the dotted line 105. Similarly, (E) and (F) of FIG. 7 respectively show the weighted signal W4 in the double direct scan distribution area Va4 and the iris control signal I weighted according to the signal W4.
4 shows the waveform of FIG. The weighting signal W4 remains at the low level as in the case of the signal W3 (regions 4 and 5 in FIG. 5).
Corresponding to the iris control signal I of the entire area E.
Level 4 remains unchanged. Therefore, the level of the iris control signal I4 before and after weighting is indicated by a solid line 104 and a dotted line 1
The same waveform as shown by 05 is obtained.

The iris control signal is output from the D / A converter 15 at such a timing as to control the lens 1 in synchronization with the video signal of a frame after a plurality of frames output from the CCD 2. In this case, the response of the iris control can be slowed.

By weighting in this manner, depending on the weighted iris control signal of the dotted line 101, the aperture control of the auto iris lens 1 can be controlled more appropriately for the imaging light from the subject in the low luminance area. It becomes possible.

In the above description, the weighting signal W
(W1 to W4) have been described as binary signals of a high level and a low level. However, the value of the weighting signal W may be a value corresponding to the average luminance value of each area, and in this case, there are more than two values. It may be a multi-valued signal. Then, the iris control signals in the region excluding the region where the average luminance value is the smallest are weighted according to the values of the corresponding weighting signals.

[0054]

As described above, according to the present invention,
Even if two subjects having different luminance level differences, such as a mixture of an indoor (low-luminance region) subject and an outdoor (high-luminance region) subject, are imaged simultaneously, the aperture control of the auto iris lens is more suitable for the low-luminance region. Since the auto iris control can be performed as described above, it is possible to realize a television camera that obtains a wide dynamic range video signal with enhanced tone reproduction capability both indoors and outdoors.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration example of a television camera according to a conventional technique.

FIG. 2 is a block diagram showing a configuration of a television camera according to a related technique of the present invention.

FIG. 3 is a block diagram showing a configuration of a television camera according to one embodiment of the present invention.

FIG. 4 is a diagram showing an example of a subject imaged by a television camera.

FIG. 5 is a diagram showing an example in which an imaging screen is divided into a plurality of regions according to the present invention.

FIG. 6 is a view showing an example of a weighting signal waveform corresponding to an area of the imaging screen in FIG. 5;

FIG. 7 is a diagram showing an example of a weighting signal and an iris control signal corresponding to an area of the imaging screen in FIG. 5;

FIG. 8 is a flowchart showing a control operation example of a CPU in the television camera according to the embodiment of the present invention.

[Explanation of symbols]

1: Auto iris lens 2: Solid-state image sensor (CC
D), 3,11: CDS (correlated double sampling) circuit, 4: AGC (automatic gain control) circuit, 5, 12:
A / D converter, 6, 13: synchronization circuit, 7: video signal processing circuit for long exposure, 8: video signal processing circuit for short exposure, 9: synthesis / gradation correction processing circuit, 10: microcomputer (CPU ), 14: weighting circuit, 1
5: D / A converter, 16: area division processing circuit.

Claims (13)

[Claims] 1. An aperture control device for a television camera, in which a long exposure video signal obtained from imaging light for exposing a subject for a long time and a short exposure video signal obtained from imaging light for exposing the subject for a short time are time-divided. A solid-state imaging device to be output, a division unit for dividing the imaging screen of the long exposure video signal into a plurality of predetermined regions, and a first region and a second region having different luminance levels of the long exposure video signal. A detecting unit for detecting, a weighting unit for applying different weights to the long-exposure video signals of the first area and the second area, and an aperture of a lens through which imaging light supplied to the solid-state imaging device passes And a control unit for controlling the weighting according to the weighted long exposure video signal. 2. The aperture control device according to claim 1, wherein the first area is an area where the average luminance level of the long exposure video signal is minimum. 3. The aperture control device according to claim 1, wherein the weighting section performs weighting to reduce a video signal level of a long exposure video signal of the second area. 4. The aperture control device according to claim 1, wherein the weighting section has a rate of decrease in the level of the long-exposure video signal of the first area larger than that of the long-exposure video signal of the second area. Aperture control device characterized in that predetermined weighting is applied. 5. The aperture control device according to claim 1, wherein the control unit supplies the weighted long exposure video signal to the lens in synchronization with a video signal from the solid-state imaging device. An aperture control device characterized by the above-mentioned. 6. A television camera, comprising: a lens unit having an aperture; and imaging light from a subject given through the lens, and a long-exposure video signal obtained from imaging light for exposing the subject for a long time. A solid-state image sensor for time-divisionally outputting a long-exposure video signal obtained from imaging light for short-time exposure, a dividing unit for dividing an imaging screen of the long-exposure video signal into a plurality of predetermined regions, A detection unit that detects a first region and a second region having different luminance levels, and a weighting unit that applies different weights to the long-exposure video signals of the first region and the second region, respectively. A synthesizing unit for synthesizing the long-exposure video signal and the short-exposure video signal, and a control unit for controlling the aperture of the lens according to the weighted long-exposure video signal. Television camera. 7. The television camera according to claim 6, wherein the weighting section performs weighting to reduce a video signal level of the long-exposure video signal of the second area. 8. The television camera according to claim 6, wherein the synthesizing unit selects the long-exposure video signal for the first area and the short-exposure video signal for the second area. A television camera, wherein an exposure video signal is selected, and the long exposure video signal and the short exposure video signal are combined. 9. A method for controlling an aperture of a television camera, wherein a long exposure video signal obtained from imaging light for exposing a subject for a long time and a long exposure video signal obtained from imaging light for exposing the subject for a short time are time-divided. Outputting the long-exposure video signal, dividing the imaging screen into a plurality of predetermined areas, detecting a first area and a second area having different luminance levels of the long-exposure video signal, respectively, Different weights are applied to the long-exposure image signals of the area and the second area, and the aperture of a lens through which imaging light supplied to the solid-state imaging device of the television camera passes is changed to the weighted long-exposure image signal. An aperture control method characterized by performing control in accordance with a signal. 10. The aperture control method according to claim 9, wherein the luminance level of the long exposure video signal in the first area is minimum. 11. The aperture control method according to claim 9, wherein said weighting step further reduces a video signal level of a long exposure video signal of said second area. Method. 12. The aperture control method according to claim 9, wherein the step of weighting is performed such that a rate of decrease in the level of the long-exposure video signal in the first area is higher than that in the second area. An aperture control method, wherein a predetermined weight is applied so as to increase the aperture. 13. The aperture control method according to claim 9, wherein the step of controlling the aperture includes transmitting the weighted long-exposure video signal to the lens so as to synchronize with the video signal from the solid-state imaging device. An aperture control method characterized in that the aperture is supplied.