JPS6029091A - Photographing device - Google Patents

Abstract

PURPOSE:To adjust rapidly and precisely the luminance of the picture signal, by repeating electrically the control of the luminance and contrast and converging the black and white levels of the picture on the CRT to the upper and lower limits of the effective photographing luminance. CONSTITUTION:The picture signal S1 is inputted to the hold circuit 20 and the black and white level signals of the picture signal held by the circuit 20 are inputted to an interruption circuit 22. The circuit 22 is inputted the signal of the black level and white level inputted interruptingly, to the signal S1 and inputted to the contrast control circuit 10. The luminance signal of the white level target detected by the sensor circuit 26 is inputted to the circuit 10 and the luminance of the black level target is inputted to the intensity control circuit 12. The circuit 10 matches the white level target luminance displayed on the CRT14 based upon the inputted measuring luminance, to the effective photographing luminance upper limit. The circuit 12 matches the black level target luminance displayed on the CRT14, to the effective photographing luminance lower limit.

Description

Detailed Description of the Invention Technical Field The present invention relates to a photographing device, and particularly to a photographing device that adjusts the brightness of a video signal so that its black level and white level become the lower and upper limits of effective photographing brightness and displays the image on a CRT for photographing. Concerning improvements to equipment.

2. Description of the Related Art Photographing apparatuses for photographing images displayed on a CRT have been well known, and are widely used, for example, for photographing diagnostic images of ultrasonic diagnostic apparatuses, for straddling, and for other purposes.

However, the photographs used with such photographic devices generally have non-linear density characteristics with respect to the amount of incident light, so in order to faithfully photograph the image displayed on a CRT using such a photographic device, it is necessary to It is necessary to consider the influence of density characteristics on the amount of incident light of the photograph used.

Figure 1 shows the general density characteristics of photographs.
AH and B1 indicate the lower limit and upper limit of the effective photographing brightness of the photograph. Therefore, when photographing an image displayed on a CRT using a photographing device, only the image in which the amount of incident light from the CRT falls within the range of effective photographing brightness A to B is photographed, and there is no difference from the displayed image. If the amount of incident light from the display image is less than the lower limit A1 of the effective shooting brightness, that part of the photograph will be solid black, and if the amount of incident light from the display image is more than the upper limit B1 of the effective photographing brightness, the part of the photograph will become solid black. That part causes halation and shatters, making it impossible to take a photograph of that part. Therefore, when photographing an image displayed on a CRT, it is necessary to adjust the amount of light of the image displayed on the CRT to within the range of effective photographing brightness A1 to B1 described above.

Here, the brightness characteristics for the CRT input signal are:
As shown in Figure 2, it has nonlinear characteristics, so the third
As shown in the figure, A of the signals input to the CRT. From B. Only signals within the range will be displayed as images on the CRT with effective photographing brightness.

Therefore, in order to display all of the information contained in the video signal as a photographable image on the CRT, the black level run 1 and white level B of the video signal input to the CRT must be adjusted. It is necessary to adjust the brightness of the video signal so that the black level and white level of the video signal match the lower limit value A and the upper limit value B of the effective photographing brightness.

FIG. 4 shows a conventional device that performs such brightness adjustment, and this device uses a contrast control circuit 10 and an intensity control circuit 12 to enable the white level and black level of the video (8) signal. The brightness is adjusted to match the upper and lower limits of the photographing brightness, and the image is displayed on the photographing CRT]4.

Here, the contrast control circuit 10 controls the CRT1.
The contrast adjustment is performed by adjusting the degree of amplification of the video signal using the gain adjuster 15. Intensity adjustment by the reduced intensity control circuit 12 is generally performed by adjusting the DC bias voltage applied to the first grid of the CRT 14.

Brightness adjustment performed using such a device begins with photographing the image displayed on the CRT 14 using the camera 16, and then adjusting the CRT based on this photograph.
RT14 Determine whether the image displayed above has been adjusted to optimal brightness. As a result, the black level of the video signal is A. and white level B. However, as shown in FIG. 5 or 6, the lower limit value and upper limit value B of the effective photographing range. If it is determined that the brightness adjustment of the image displayed on the CRT 14 is not appropriate, the black level A of the video signal displayed on the CRT 14. and white level B. is the lower limit value A of the effective shooting range. and the upper limit Bo′
Control intensity and contrast.

Here, when the intensity or contrast ratio of the CRT 14 is changed, the black level AO' of the video signal is changed.
and white level B. ′ both move at the same time. For this reason, the intensity and contrast are fully adjusted and the black level Ao and white level B of the video signal are adjusted. ' is the lower limit value A of the effective shooting range. and upper limit B. In order to control the movement of the black level A0 and white level B0' separately in your head, adjust the intensity and contrast alternately to control the movement of Ao and Bo' independently. Shiten and B. It is necessary to control it so that it matches.

5 and 6 show the black level A of the video signal as a result of photographing the image displayed on the CRT, 14. and white level B. is the lower limit value A of the effective shooting range. and upper limit B
. An example of the operation procedure for brightness adjustment when it is determined that the brightness does not match is shown.

For example, as shown by the solid line in FIG. 5, when the black level and white level of the video signal are at the positions AO and BO', the intensity is first lowered to the black level A. ′
is the lower limit value A of the effective shooting range. to be located. However, since the amplitude is still large in this state, the contrast is then lowered and the amplitude of the video signal is controlled to be small. When the contrast is lowered in this way, the previous lower limit value A is reached. Since the black level Ao', which was made to match the black level Ao', shifts, the intensity is then lowered again, thereby adjusting the black level Ao' and white level Bo' to the lower limit value A of effective photographing brightness. and upper limit B. , and finish adjusting the brightness.

The operating procedure for brightness adjustment shown by the solid line in FIG. 5 explained above is to control the intensity, adjust the black level of the video signal to the lower limit of the effective shooting range (i^A By controlling the white level of the video signal, the white level of the video signal is adjusted to the upper limit value BO of the entire effective shooting range, but conversely, as shown by the broken line in Figure 5, the black level of the video signal is adjusted by controlling the contrast. may be adjusted to the lower limit value A of the effective photographing range, and the white level of the video signal may be adjusted to the upper limit value B of the effective photographing range by controlling the intensity.

Further, as shown in FIG. 6, the black level and white level of the video signal are A. If it is at the ', go' position, first set the amplitude of the contrast level-up video signal to A. and B. Set equal to the amplitude of However, when the contrast is increased in this way, the eight black levels shift, so next, the intensity is increased to adjust the black level A (1 and white level B) of the video signal, the lower limit of the effective shooting range Ao and The brightness adjustment is completed by matching the upper limit of 1st page B.

However, in such conventional devices, when adjusting the intensity and contrast, the adjustments are first made manually after taking a photograph, and the black level A'o and contrast of the video signal are determined by relying on intuition and experience. The white level Bt is the lower limit value A of the effective shooting range. and upper limit B. Since the brightness is controlled so as to match the brightness, the brightness adjustment operation becomes very complicated, and there is a drawback that the brightness cannot be adjusted quickly and accurately.

Furthermore, in such conventional devices, even if the image displayed on the CRT 4 can be adjusted to the optimal shooting brightness,
If there is a change in the brightness of the image displayed on the CRT over time due to deterioration of the electron gun and phosphor screen of the CRT 14 itself or drift of the electronic circuit, manual operation must be performed again to correct the change. However, the drawback was that the intensity and contrast had to be readjusted, relying on so-called intuition and experience.

Purpose of the Invention The present invention was made in view of the above-mentioned conventional problems, and its purpose is to quickly and accurately capture the black and white levels of a video signal when capturing an image displayed on a CRT. An object of the present invention is to provide a photographing device capable of adjusting brightness so that it matches a lower limit value and an upper limit value of brightness.

Structure of the Invention In order to achieve this object, the apparatus of the present invention adjusts the brightness of the video signal so that the point level and white level match the lower and upper limits of effective photographing brightness, and displays the image on a CRT for photographing. In a photographing device, there is a hold circuit that holds the black level and white level signals included in the video signal, and the black level and white level signals held in this hold circuit are input as an interrupt input to the video signal to control the black level and white level. An interrupt circuit that displays an image on a CRT as a level target, a sensor circuit that uses a photosensor to measure the brightness of a black level and white level target displayed on a CRT, and one side that is measured by this sensor circuit. An intensity control circuit that controls the intensity of the CRT based on the brightness of the target, and a contrast control circuit that controls the contrast of the CRT based on the brightness of the other target measured by the sensor circuit, and displays on the CRT. The main feature of the present invention is to make the black level and white level match the lower and upper limits of effective photographing brightness.

Example Next, a preferred embodiment of the present invention will be described based on the drawings.

Note that members corresponding to those of the conventional example shown in FIG. 4 will be described with the same reference numerals.

FIG. 7 shows a preferred embodiment of the photographing apparatus of the present invention. The black level A of the video signal displayed on the CRT by repeatedly controlling the contrast and intensity of the video signal. ' and white level Bo' are the lower limit value A of effective shooting brightness
. and upper limit B. The brightness is controlled so that the brightness automatically converges on the brightness.

First, for example, when a video signal SI as shown in FIG. 8 is input, this video signal S1 is input to the hall echo circuit 20. The hold circuit 20 holds the lowest amplitude value of the input video signal SI as the black level, and holds the maximum amplitude value of the video signal S1 as the white level. In the embodiment, the hold circuit 20 holds the black level by holding the pedestal voltage included in the video signal S, and holds the white level by holding the maximum amplitude f7I in the input video signal S1.
-, - This is done by doing the following. The black level, - level and white level signals of the video signal held by the halt circuit 20 are input to the interrupt circuit 22.

The interrupt circuit 22 converts the black level and white level signals inputted in this manner into a video signal S1 as shown in FIG.
An interrupt input is made to the contrast control circuit 10. Here, when the interrupt circuit 22 interrupts the black level and white level signals, the black level and white level signals are sent to the black level and white level targets as shown in FIG. Vertical and horizontal synchronizing signals V of the CRT 14 so that the image is displayed as (a)
S.

This is done in synchronization with HS.

And, like this, the contrast control circuit 1.

The amplitude of the interrupt video signal S2 inputted to the CRT 14 is controlled by this contrast control circuit, and then inputted to the CRT 14.

The characteristic feature of the present invention is that the target luminance of the black level and white level of the video signal is displayed on the CRjlJ as described above, and the luminance of the target of the displayed black level and white level is the lower limit and upper limit of the effective shooting luminance. The purpose of this method is to repeatedly control the contrast and intensity so that the contrast and intensity become sharp, thereby automatically converging the black level and white level of the video signal displayed on the CRT 14 to the lower and upper limits of effective shooting brightness. It is possible.

Such brightness control controls the intensity so that the brightness of the black level target displayed on the CRT 14 becomes the lower limit of effective shooting brightness, and the brightness of the white level target becomes the upper limit of effective shooting brightness. On the contrary, by fully controlling the contrast, the result is even better.
The intensity may be constrained to 1 so that the brightness of the white level target becomes the upper limit of the effective shooting brightness, and the contrast is controlled so that the brightness of the black level target becomes the lower limit of the effective shooting brightness.

The device of this embodiment adopts the former brightness adjustment method. Therefore, in the device of this embodiment, the photosensor 24 is used to adjust the black level and white level targets displayed on the CRT 14. A sensor circuit 26 for measuring brightness is provided, and the brightness of the white level target detected by this sensor circuit 26 is input to the contrast control circuit 10, and the brightness of the black level target detected in the same way is input to the intensity. It is input to the control circuit 12.

Contrast control circuit 10. controls the amplification degree of the video signal input to the CRT 14 based on the measured brightness of the white level target input in this way, and sets the brightness of the white level target displayed on the CRT 14 to the upper limit of the effective shooting brightness. Match.

In addition, the intensity control circuit 12 controls the intensity control circuit 12 based on the measured luminance of the black level target inputted from the sensor circuit 26.
．． Controls the intensity of CRT14,
The brightness of the black level target displayed above is made to match the lower limit of effective shooting brightness.

Such contrast and intensity control is provided by C.
It is necessary to perform this in constant synchronization with the raster screen scanning of RT14.

For this reason, the device of the embodiment is provided with a sync separation circuit 28 that outputs a vertical sync signal VS and a horizontal sync signal H82 based on the input video signal, and a vertical sync signal output from this sync separation circuit 28. vS and the horizontal synchronization signal H8 are input to the time base circuit 30. The time base circuit 30 controls the hold circuit 20 and the interrupt circuit 22 based on the vertical synchronization signal S and the horizontal synchronization signal H8 input in this way, and controls the black level and white level targets displayed on the CRT 14. It also controls the contrast control circuit 10 and the intensity control circuit 12, and adjusts the contrast and intensity control timing.

In this way, according to the apparatus of the present invention, each time the CRT 14 performs raster screen scanning, contrast and intensity control is repeatedly performed, and the black level and white level of the video signal displayed on the CRT are The brightness is adjusted so that the brightness automatically converges to the lower and upper limits of the effective photographing brightness.

Therefore, according to the apparatus of the present invention, it is possible to quickly and accurately set contrast and intensity to optimal photographing conditions, compared to conventional manually operated photographing apparatuses.

Note that the contrast and intensity control may be performed alternately each time the raster screen is scanned.
It is also possible to perform these operations simultaneously during scanning of the same Lasque image.

Next, detailed embodiments of the apparatus of the present invention will be described based on the drawings.

FIG. 11 shows an embodiment of the details of the photographing device of the present invention, and as shown in FIG. When an instruction is given to photograph an image, various signals shown in FIGS. 12 to 14 are output from the time base circuit 30, and the black level and white level of the video signal are automatically adjusted to the lower and upper limits of effective photographing brightness. After the adjustment is completed, a shutter control signal g' is output, and the image displayed on the CRT 14 is photographed by the camera 16.

Here, the characteristics of this embodiment are such that the brightness adjustment i of the video signal is performed, black level and white level targets are alternately displayed on the CRT 14 for each raster, and the black level and white level targets are The purpose is to alternately control the intensity and contrast in synchronization with the white level display.

Next, details of this embodiment will be explained based on the drawings.

In the embodiment, the hold circuit 20 includes a sample hold circuit 32 and a peak hold circuit 34. Then, as shown in FIG. 13, the sample hold circuit 32
The peak hold circuit 34 holds the black level signal of the video signal S based on the sample gate signal a output from the time base circuit 30, and the peak hold circuit 34 holds the black level signal of the video signal S1 based on the signal S output from the time base circuit 30. Holds the white level signal. In this way, each hold circuit 3
The black level signal S3 and the white level signal S4 held by 2.34 are input to the interrupt circuit 22.

The interrupt circuit 22 includes a changeover switch 36 that selects the output of each of the hold circuits 32 and 34, and a changeover switch 38 that interrupts the selected signal into the video signal S1. Here, the changeover switch 36 switches its input terminal based on the changeover signal S output from the time base circuit 30, and outputs either the black level signal S3 output from the sample hold circuit 32 or the output from the peak hold circuit 34. Select one of the white level signals and input it to the selector switch 38. The changeover switch 38 normally outputs the signal from the video signal S1 to the contrast control circuit 10, but when the interrupt signal C is output from the time base circuit 30, the changeover switch 38 temporarily switches its input terminal. Then, a signal of black level S3 or white level S4 selected by switch 36 is inserted into this video signal S.

FIG. 13 shows a timing chart of how to interrupt the video signal S1 with a black level signal.

The contrast control circuit 10 thus adjusts the contrast by amplifying the video signal S2 outputted from the changeover switch 38 by a predetermined magnification using the multiplier 40.
Input to CRT14. As a result, an image of the white level or black level is displayed on the CRT 14.

In the embodiment, the interrupts of the black level signal S3 and the white level signal S4 in the interrupt circuit 22 are performed alternately every raster and image scan, as shown in the switching signal of FIG. Therefore, a black level target and a white level target are alternately displayed on the CRT 14 every raster and image scan.

The luminance of the black level and white level targets alternately displayed as images fJ on the CRT 14 in this manner is determined by the sensor circuit 26. In the embodiment, the sensor circuit 26 is provided with a telescope (not shown), and the target force and light of the black level and white level displayed on the CRT 14 are inputted to the photosensor 24 through this telescope. are doing. The brightness of the target detected by the photosensor 24 in this manner is converted into a voltage S corresponding to the detected brightness by the photosensor 1 circuit 42 and output.

Here, as shown in FIG. 14, the target display 1d on the CRT 14 is performed only when the time base circuit 30 outputs the interrupt signal C. Therefore, the photosensor circuit 42 outputs the The signal S, which is output from the time base circuit 30 outputs a voltage corresponding to the target luminance of the black level or white level only when the interrupt signal - is output from the time base circuit 30. Therefore, the - -11-..., JJ-1 number of items 9
A sample hold circuit 4 holds the signal voltage S output from the photosensor circuit 42 based on the sample gate signal d output from the time base circuit 30.
The signal S held by the sample and hold circuit 44 is outputted to the intensity control circuit 12 and the contrast control circuit 10, respectively.

The intensity control circuit 12 includes a reference voltage setter 46 that outputs a voltage corresponding to the target brightness of the black level target displayed on the CRT 14, and a comparison unit 4
8, the black level target hold signal S6 outputted from the sample hold circuit 44 and the reference voltage outputted from the reference voltage setter 46 are compared and calculated;
The voltage difference between the two is input to the automatic intensity adjustment circuit 50. The intensity automatic adjustment circuit 50 samples and holds the differential voltage inputted in this way in synchronization with the sample gate signal e output from the time base circuit 30, and controls the CRT 14 so that this differential voltage becomes zero.
Automatically adjust the intensity of In the embodiment, the automatic intensity adjustment circuit 50 adjusts the intensity by controlling the DC bias voltage applied to the first grid of the CRT 14.

Further, the contrast control circuit 10 of the embodiment includes a CRT 14
It has a reference voltage setter 52 that outputs a reference voltage corresponding to the target setting brightness of the white level target displayed above, and the comparing section 54 holds the white level target input from the sample hold circuit 44. The signal S6 and the reference voltage inputted from the reference voltage setter 52 are compared and calculated, and the difference voltage between the two is inputted to the automatic contrast adjustment circuit 56. Contrast automatic adjustment circuit 56
samples and holds the differential voltage input in this way based on the sample gate signal f output from the time base circuit 30, and automatically adjusts the amplification factor of the multiplier 40 so that this differential voltage becomes zero. There is.

The present embodiment has the above configuration, and its operation will be explained next.

First, as shown in FIG. 12, when the photographing switch 18f is turned on and an instruction is given to photograph all images displayed on the CRT 14, the black level contained in the video signal S1 is determined by the sample hold circuit 32 and the peak hold circuit 34. and white level signal S3. S4 is held. and,
The thus held black level signal S3 and white level signal S4 are alternately input into the video signal S1 in the interrupt circuit 22 every raster screen scan, and are input to the video signal S1 via the multiplier 40. and is input to CR'T14.

Therefore, a black level target and a white level target are alternately displayed on the CRT 14 every scan of one screen.

Here, when a black level target is displayed as an image on the CRT 14, the luminance of the target is measured by the sensor circuit 26 and input to the intensity control circuit 12. The intensity control circuit 12 compares the luminance of the black level target inputted in this manner with the target luminance of the black level target preset by the reference voltage setter 46, and determines that the difference between the two luminances becomes zero. CRT
14 intensities are controlled.

Further, when a white level target is displayed on the CRT 14, the brightness of this target is measured by the sensor circuit 26 and input to the contrast control circuit 10. The contrast control circuit 10 compares the brightness of the white level target input in this way with the target setting brightness of the white level target preset by the reference voltage setter 52,
The amplification degree of the multiplier 40, that is, the contrast, is adjusted so that the difference between both luminances becomes zero.

In this way, the apparatus of this embodiment adjusts the intensity and the white level in synchronization with the image display of the target each time the black level and white level targets are alternately displayed on the CRT 14 for each screen scan of one rask. Contrast control is repeatedly performed to converge the black level and white level of the video signal displayed on the CRT 14 to the lower and upper limits of effective photographing brightness.

As shown in FIG. 12, the brightness adjustment by controlling the intensity and contrast is completed within 20 to 30 raster screen scanning periods after the photographing switch 18 is turned on. When this is completed, the interrupt signal C input from the time base circuit 30 to the switch 38 of the interrupt circuit 22 is turned off, and the video signals S,
Interruptions of white level and black level signals are stopped.

As a result, only the image based on the video signal S1 is displayed on the CRT 14.

Then, in synchronization with the cancellation of such an interrupt, a shutter control signal g is outputted from the time base circuit 30 to the camera 16, and the image displayed on the CRT 14 is transmitted to the camera 16.
Photographed by.

In this way, according to the device of this embodiment, the brightness of the video signal displayed on the CRT 14 is adjusted every time the photographing switch 18 is turned on, so that the image displayed on the CRT 14 is always kept at its highest level. This makes it possible to take pictures under the following brightness conditions.

Further, in the apparatus of the present invention, the luminance of the black level and white level of the video signal displayed on the CRT 14 are mutually controlled by the set voltages of the reference voltage setters 46 and 52 of the intensity control circuit 12 and the contrast control circuit 10. Since the brightness can be set completely independently and mechanically without any influence, this adjustment can be done extremely accurately and quickly compared to conventional devices that rely on human intuition and experience to adjust the brightness. can.

Further, according to the device of this embodiment, the reference voltage setting device 46 can
, 52 by adjusting the set voltages of CR
It is possible to adjust the luminance of the black level and white level of the video signal displayed as an image on T14 to arbitrary values.

Furthermore, according to the device of this embodiment, even when an image is displayed on the CRT 14 with the black level and white level of the video signal intentionally shifted from the lower and upper limits of effective photographing brightness, the standard Based on the set voltages of the voltage setters 46 and 52, it is possible to quantitatively determine which amplitude portion of the video signal S1 is being photographed.

Therefore, for example, when a video signal is displayed on the C, RT 14 with the brightness adjusted to the optimum shooting condition, the reference voltage setter 46 of the intensity control circuit 12 is adjusted to only have the brightness of the black level of the video signal. If you consciously lower the brightness and take a picture, the amplitude part of the video signal that is below the lower limit of the effective shooting brightness will not be taken, but even in such a case, the shot picture will be displayed on the CRT 14. Based on the set voltage of the reference voltage setter 52 of the contrast control circuit 10, it is possible to quantitatively know which part of the amplitude of the video signal is being photographed without comparing it with the video signal that is being photographed.

The device of this embodiment can also adjust the brightness of the video signal to the optimal shooting conditions by remote control. In this case, the intensity control circuit 12 and the contrast control circuit 1
The set voltages of the reference voltage setters 46 and 52 may be adjusted by remote control.

In the embodiment shown in FIG. 11, the intensity and contrast of the image displayed on the CRT are alternately controlled every raster screen scan, but the present invention is not limited to this. For example, black level and white level targets may be displayed simultaneously within the same raster scanning screen, and the intensity and contrast may be controlled while the same raster scanning screen is being scanned.

FIG. 15 shows such an implementation of the present invention, in which the apparatus of the embodiment detects a black level target (Ea) and a white level target within the same raster scanning screen of a CRT 14, as shown in FIG. The level target (Eb) is displayed as an image at the same time, and both the intensity and contrast are controlled simultaneously during the same Lasque screen scanning so that the white level and black level of the video signal become the lower and upper limits of effective shooting brightness. There is.

When the automatic photographing switch 18 is turned on and an instruction is given to photograph the image displayed on the CRT 14, the time base circuit 30 outputs the signal shown in FIG. 17 in synchronization with the vertical synchronizing signal VS, and the image is Signal brightness control is started.

Here, when a video signal S is input, the white level and black level of this video signal S1 are held in a sample hold circuit 32 and a peak hold circuit 34,
The hold signal S3. S4 is input to the interrupt circuit 22, respectively.

In this embodiment, the interrupt circuit 22 is connected to the switch 36 so that the black level interrupt signal output from the time base circuit 30 is output from the time base circuit 30.
The white level interrupt signal i, which is input to the switch 36 and also output from the time base circuit 30, is input to the switch 36.
b. Also, for each of these interrupt signals, i is N
'AND circuit 60f! : It is also input to the switch 38 via.

Therefore, as shown in FIG. 18, when the time base circuit 30 outputs a black level interrupt signal, the switch 38
is turned off, cutting off the input of the video signal S to the multiplier 40, and instead turning on the switch 36a, the black level signal S3 output from the sample hold circuit 32 is
is input as an interrupt.

When the white level interrupt signal l is output from the switched time base circuit 30, the switch 38 similarly turns off, cutting off the input of the video signal S1 to the multiplier 40, and instead, the switch 36b turns on. Then, the white level signal S4 outputted from the peak hold circuit 34 is input as an interrupt.

In this way, from the interrupt circuit 22 of this embodiment (c) the video signal S1 is supplied with a black level signal S3 and a white level signal S.
The signal S2 with the interrupt input of 4 is output and input to the multiplier 40.

Therefore, on the CRT 14 to which the signal S2 is input via the multiplier 40, black level and white level targets are simultaneously displayed as images within the same Lasque scanning screen, as shown in FIG.

The characteristic feature of this embodiment is that, based on the black level and white level targets displayed simultaneously within the same raster scanning screen on the CRT 14, the intensity and contrast are adjusted every time one raster screen is scanned. The goal is to control both at the same time.

Therefore, the sensor circuit 26 of this embodiment includes two sets of photosensors 24a and 24b that measure the luminance of these black level targets and white level targets separately and independently.
and these photosensors 24a.

Two sets of photosensor circuits 42'a and 42b are provided to convert the output of 24b into voltage.

Here, the photosensor circuit 42a is a CRT 14
A DC voltage corresponding to the luminance of the black level target displayed above is output and input to the intensity control circuit 12. The other photosensor circuit 42'b is
The contrast control circuit 1 outputs a DC voltage corresponding to the brightness of the white level target displayed on the CRT1'4.
It is entered as 0.

Since the apparatus of this embodiment has the above configuration, as shown in FIG. A signal as shown in FIG. 17 is output.

By outputting this signal, black level and white level targets are simultaneously displayed as images on the CRT 14 as shown in FIG. Both intensity and contrast are controlled simultaneously during the same Lasque screen scan. Then, such intensity and contrast control is performed for 20 to 30 minutes after turning on the photographing switch 18.
Repeatedly within one raster screen scan, CR
The black level and white level of the video signal displayed on T14 are made to converge to the lower and upper limits of effective photographing brightness.

After such brightness control is completed, the time base circuit 30 outputs the shutter control signal g, and the camera 16 takes a picture.

In this way, in the apparatus of this embodiment, since both intensity and contrast are controlled simultaneously during the same raster screen scan, brightness adjustment can be performed more quickly than in the embodiment shown in FIG. It becomes possible to do so.

In addition, in the embodiment shown in FIG. 11 or FIG. 15,
In both cases, the CRT1 is controlled by the intensity control circuit 12.
4. Control the intensity of the black level target to match the lower limit of effective shooting brightness, and control the contrast of the CRT 14 by the contrast control circuit 10 to match the white level target to the upper limit of effective shooting brightness. The black level and white level of the video signal displayed on the CRT 14 are converged to the lower and upper limits of the effective photographing luminance. However, the present invention is not limited to this. The intensity of the white level target is controlled to match the upper limit of effective shooting brightness, and the contrast control circuit 10 causes the CRT's contrast=i=control nL black level target to match the lower limit of effective shooting brightness. Especially Q.
It is possible to converge the black level and white level of the video signal displayed on the CRT to the lower and upper limits of effective photographing brightness.

In this case, the reference voltage setting value 46 of the intensity control circuit 12 is set to a reference voltage corresponding to the target brightness of the white level target, and the contrast control circuit 100
The reference voltage setter 52 may be set to a reference voltage corresponding to the target brightness of the black level target. In this case, the comparison section 48 of the intensity control circuit 12 receives the measured brightness of the white level target measured by the sensor circuit 26, and the comparison section 54 of the contrast control circuit 10 receives the measured brightness of the white level target as well. The measured brightness of the measured black level target will be input.

Effects of the Invention As explained above, according to the apparatus of the present invention, the intensity and contrast are repeatedly controlled electrically, and the black level and white level of the video signal displayed on the CRT are adjusted to the effective shooting brightness. Since the brightness is converged to the lower limit value and the upper limit value, it is possible to adjust the brightness of the video signal displayed on the CRT extremely quickly and accurately.

[Brief explanation of the drawing]

Figure 1 is a density characteristic diagram for the amount of incident light in a photo, Figure 2 is a luminance characteristic diagram for the input signal of C1 (T), and Figure 3 is a graph for CR
Figure 4 is a simple illustration of a conventional photographing device, and Figures 5 and 6 are explanations showing the brightness adjustment procedure when photographing an image displayed on a T. 7 is a block diagram showing a preferred embodiment of the device of the present invention, FIGS. 8 and 9 are explanatory diagrams showing signals in each part of the device shown in FIG. 7, and FIG. 10 is a block diagram showing a preferred embodiment of the device of the present invention. FIG. 11 is a circuit diagram showing a detailed embodiment of the device of the present invention, and FIGS. 12 to 14 are the device shown in FIG. 11. 15 is a circuit diagram showing another embodiment of the device of the present invention, FIG. 16 is an explanatory diagram of a luminance measurement target displayed on the CRT shown in FIG. 15, FIG. 17 and FIG. 18 is a timing chart diagram of the apparatus shown in FIG. 15. 10...Contrast control circuit 12...Intensity control circuit 14...CRT 16...Camera 20...Hold circuit 22...Interrupt circuit 24...Photo sensor 26...Sensor circuit Applicant Aloka Co., Ltd. I! Ill:@-world

Claims (1)

[Claims] (1) The brightness of the video signal is adjusted so that its black level and white level become the lower and upper limits of effective photographing brightness.
In a photographing device that displays images on RT, there is a hold circuit that holds black and white level signals included in the video signal, and a hold circuit that interrupts the black and white level signals held in this hold circuit into the video signal. An interrupt circuit that receives input and displays an image on a CRT as a black level and white level target, a sensor circuit that uses a photosensor to measure the brightness of the black level and white level targets displayed on the CRT, and this sensor circuit. an intensity control circuit that controls the intensity of the CRT based on the brightness of one target measured by the sensor circuit; and an intensity control circuit that controls the intensity of the CRT based on the brightness of the other target measured by the sensor circuit.
a contrast control circuit that controls the contrast of T;
What is claimed is: 1. A photographing device comprising: a CRT, which converges a black level and a white level displayed on a CRT to a lower limit value and an upper limit value of effective photographing brightness. (2. In the apparatus described in claim (1), the intensity control circuit controls the intensity of the CRT based on the luminance of the black level target measured by the sensor circuit to enable the luminance of the black level target. The contrast control circuit controls the contrast of the CRT based on the brightness of the white level target measured by the sensor circuit to match the brightness of the white level target with the upper limit of effective photographing brightness. (3) In the device according to claim (1), the contrast control circuit controls the contrast of the CRT based on the luminance of the black level target measured by the sensor circuit to adjust the black level. The intensity control circuit causes the brightness of the CRT target to match the upper limit of the effective shooting brightness of the CRT based on the brightness of the white level target measured by the sensor circuit. A photographing device characterized by: (4) Claim Fi1. In the device according to any one of (2) and (3), the interrupt circuit receives the white level and black level signals held in the hold circuit. is input into the video signal alternately every raster and one screen scan to display the white level and black level targets on the CRT alternately every one raster and one screen scan. An imaging device characterized by using a photosensor to alternately measure the brightness of a target at a white level and a black level displayed on a CRT every scan of one raster screen. (5) Claim (11). (2), (In the apparatus described in any one of (31), the interrupt circuit interrupts and inputs both the white level and black level signals held in the hold circuit to the video signal that is being scanned on the same raster screen. Both white level and black level images are simultaneously displayed on the same raster scanning screen of Targetera 1fcRT, and the sensor circuit uses two photosensors to measure the brightness of both the white level and black level targets displayed on the CRT. A photographing device characterized in that it performs the following during scanning of the same Lasque screen.