JPH03108882A - Photometric circuit - Google Patents

Abstract

PURPOSE:To obtain a pickup pattern suitable for the situation by providing a means limiting an input to a photometric circuit and excluding an input picture signal from an object of photometry when the level of the input picture signal is higher than a prescribed level and its consecutive time has a prescribed period. CONSTITUTION:A picture signal is integrated at a prescribed time constant by a photometry integration device 56 and the result is outputted as a control signal for an AGC circuit and an aperture control circuit or the like. Moreover, the picture signal is fed to an input terminal of an integration device 51 and a comparator 54. An output signal of the comparator 54 is normally at an L level and but at an H level only for a period td when a picture signal level is considerably high. A switch 55 is closed when the output signal of the comparator 54 is at an L level and opened when at an H level. Thus, the picture signal is not fed to the photometry integration device 56 for the period td when a picture signal level is considerably high and the picture signal is excluded from an object of photometry.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a photometry circuit for a video camera device, which includes a photometry means that measures light using an image signal.

[Prior Art 1] In recent years, video camera apparatuses such as electronic cameras that obtain image signals using a solid-state image element such as a COD (charge coupled device) as an image carrier have been put into practical use.

FIG. 14 is a configuration diagram of the electronic endoscope VT device, in which the electronic endoscope a device @1 includes an electronic scope 2, which is elongated so as to be inserted into a body cavity, and an electronic scope 2 (not shown). The body unit 3 to which the universal cord is connected, and the body cavity site 5 based on the output signal of the body unit 3.
and a monitor 4 for displaying subjects such as.

A light guide 6 that transmits illumination light is inserted into the insertion section of the electronic scope 2, and transmits the illumination light supplied from the main unit 3 to the input end to the output end, and from the output end to the intrabody cavity site 5. The direction is to be illuminated. The light reflected from the intrabody cavity site 5 is focused by the objective lens 7 and m*
The light enters the element 8, undergoes photoelectric conversion, becomes an image signal, and reaches the main unit 3.

Further, the electronic scope 2 has a function of inserting a treatment instrument 10 into a body cavity via a channel 9. There are many types of treatment tools 10 depending on the purpose, such as a treatment tool with the function of injecting a staining agent or an image-enhancing agent, a treatment tool with the function of removing a part of tissue in a body cavity, etc., and most of them are made of white Teflon or metal. It is being

The main unit 3 includes a light source section 20 that illuminates the subject;
It consists of an image signal processing section 30 that outputs a video signal to the monitor 4. The light source section 20 includes a lamp 21 and this lamp 21.
an aperture control circuit 23 that generates a control signal to variably control the frontage ratio of this aperture 22, and an aperture control circuit 23 that measures the illuminance of light incident on the image sensor 8 from an image signal. The image signal processing section 30 includes an AGC circuit 31 that amplifies the image signal to an appropriate level, and a photometric circuit 24 that generates a signal to the aperture control circuit 23. Measure AGC
A photometric circuit 33 that generates signals to the circuit 31, and 16 signal processing circuits 3 that perform various signal processing and output to the monitor 4.
It consists of 2.

The photometric circuits 24 and 33 are roughly divided into an average photometric circuit and a peak photometric circuit. The average photometry circuit is a circuit that detects the average value of the image signal level of the entire screen and generates a signal,
When the average value of the image signal level is high, the aperture of the diaphragm 22 is narrowed to reduce the amount of illumination light m directed toward the intrabody cavity site 5. The peak photometry circuit is a circuit that detects the maximum value of the image signal level and generates a signal, and when the maximum value of the image signal level is high, the aperture of the diaphragm 22 is narrowed and illumination light is irradiated toward the intrabody cavity site 5. It is designed to reduce the amount of light.

The AGC circuit is a circuit that amplifies a low image signal level that cannot be compensated for even by widening the aperture 220 to the maximum and maximizing the amount of illumination light to an appropriate level.

When the electronic scope 2 is inserted into the body cavity and the treatment instrument 10 is inserted through the chitunnel 9, an image shown in the example of FIG. 15 can be observed on the monitor 4.

FIG. 16 shows a certain horizontal scanning line A- of the image shown in FIG.
Focusing on A', the image signal level is illustrated in time series of horizontal positions. The treatment instrument 10 protrudes at a position closer to the m-image element 8 than the intrabody cavity site 5, and since it is made of white Teflon or the like, it reflects the illumination light with high efficiency.
As shown in FIG. 6, the image signal level VS is much higher than the average value Va of the image signal level of the intra-body cavity region 5. Therefore, the photometric circuit 24.33 has a high average value in the average photometric circuit, and a high maximum value in the peak photometric circuit, so the signal generated by the photometric circuit 24.33 is no longer an appropriate value, and 5 decreases, and the amplification degree of the AGC circuit 31 also decreases. Therefore, the entire image on the monitor 4 becomes dark.

A prior art technique for reducing the influence of such a change in the level of an image signal in a specific portion of a captured image on photographing a subject is illustrated in, for example, Japanese Patent Laid-Open No. 110369/1983.

[Problem to be Solved by the Invention] The above prior art example is effective only when the peripheral part of the photographing screen has a subject with higher brightness than the center part of the screen, and an electronic endoscope device is taken as an example. However, it is not effective for subjects with high brightness from the periphery of the screen to the center of the screen due to treatment instruments or the like.

The present invention has been made in view of the above-mentioned points, and an object of the present invention is to provide a photometry circuit that prevents a subject having a higher tlU than the average brightness of the photographing screen from affecting the entire photographing screen. .

[Means and effects for solving the problem] The photometric circuit of the present invention includes: an integrating means for integrating an input image signal with a predetermined time constant; a comparing means for comparing the output of the integrating means with the input image signal; Means is provided for limiting the input to the photometric circuit based on the output signal of the comparing means.

With this configuration, if the input image signal is higher than a predetermined value and its duration is a predetermined period, the input image signal is excluded from the photometry target.

[Example] Hereinafter, the present invention will be described in detail with reference to the drawings.

1 and 2 relate to a first embodiment of the present invention; FIG. 1 shows the configuration of a photometric circuit, and FIG. 2 is an explanatory diagram showing the operation of the photometric circuit.

A photometric circuit 50 shown in FIG. 1 has the configuration of a photometric circuit for a video camera device such as an electronic endoscope, and includes an integrator 51, a bias power source 53, and an addition that adds the output of the integrator 51 and the bias power source 53. a comparator 54 that compares the image signal with the output of the adder 52, a switch 55 that turns on and off the image signal according to the output of the comparator 54, and a switch 55.
The photometric integrator 56 integrates the image signal transmitted through the photometric integrator 56.

In FIG. 1, an image signal is supplied from the input end of a photometric circuit 50 to a photometric integrator 56 via a switch 55.
This photometric integrator 56 integrates with a predetermined time constant,
It is designed to be output as a control signal for the AGC circuit, aperture control circuit, etc.

This image signal is also applied to the input ends of the integrator 51 and comparator 54.

The image signal inputted to the integrator 51 and having a period td during which the signal level of the image signal becomes significantly high, as shown by the solid line in FIG. At step 52, the potential vb of the bias power supply 53 set to the minimum value of the image signal 5) level is added to the second voltage.
As shown by the broken line in FIG. 5A, the signal level of the image signal becomes an averaged signal level, which is applied to one input terminal of the comparator 54. Further, the other input terminal of the comparator 54 receives the same image signal as the input terminal of the integrator 51, which has a portion where the signal level is extremely high and is indicated by a solid line in FIG. 2(a). The output signal of the comparator 54 is normally II L 11, as shown in FIG. 4(b), and becomes II I'11 only during the period td when the image signal level is significantly high. The switch 55 is on when the output signal of the comparator 54 is "L11" and off when the output signal is "H".

Therefore, during the period td in which the signal level of the image signal becomes significantly high, the image signal is no longer applied to the photometric integrator 56 and is excluded from the photometric target.

By using this photometry circuit and appropriately selecting the time constant of the integrator and the potential vb of the bias power supply, for example, in an electronic endoscope, an image signal of a high brightness object such as a treatment tool can be applied to the photometry integrator. First, the phenomenon in which the entire image becomes brighter due to the reduction in the amplification degree of the AGC circuit and the closing of the aperture by the aperture control circuit is eliminated, making it easier to observe the subject.

3 and 4 relate to a second embodiment of the present invention, FIG. 3 shows the configuration of a photometric circuit, and FIG. 4 is an explanatory diagram showing the operation of the photometric circuit.

The photometric circuit 60 shown in FIG. 3 has the same configuration as the first embodiment, and includes an integrator 51, a subtracter 62 for subtracting the output signal of the integrator 51 from the image signal, and a reference power source 6.
3, a comparator 54 that compares the output signal of the subtracter 62 and the reference power source 63, a switch 55 that turns on and off the image signal according to the output of the comparator 54, and integrates the image signal via the switch 55. and a photometric integrator 56.

In this embodiment, the image signal is supplied from the input end of the photometric circuit 60 to the photometric integrator 56 via the switch "f-55," and is integrated by the photometric integrator 56 at a predetermined time constant. It is designed to be output as a υ control signal for an aperture control circuit, etc.

The image signal is also applied to the input ends of the integrator 51 and the subtracter 62.

The image signal input to the integrator 51 and having a period td in which the signal level of the image signal shown by the solid line in FIG. The signal level becomes the signal level shown by the broken line in (a), and is subtracted from the image signal level by the subtracter 62.
As shown in FIG.
It is added to one input end of 4. Further, the other input terminal of the comparator 54 is connected to the base III! The base tp potential Vref of the power supply 63 is applied.

The output signal of the comparator 54 is normally 111 jl as shown in FIG. . The switch 55 is on when the output signal of the comparator 54 is 11 L jl, and is off when the output signal is 1''.

Therefore, during the period td in which the signal level of the image signal is significantly high, the image signal is no longer applied to the photometric integrator 56 and is excluded from the photometric target.

Therefore, in this embodiment as well, by appropriately selecting the time constant of the integrator and the reference potential Vref of the reference power source, the first
Effects similar to those of the embodiment can be obtained.

5 and 6 relate to a third embodiment of the present invention, FIG. 5 shows the configuration of a photometric circuit, and FIG. 6 is an explanatory diagram showing the operation of the photometric circuit.

The photometric circuit 70 shown in FIG. 5 has the same configuration as the first embodiment, and includes an integrator 51, a subtracter 62 for subtracting the output signal of the integrator 51 from the image signal, and a reference power source 6.
3, and the subtracter 62 whose potential is higher than the potential of the base t\main power supply 3.
a clip circuit 74 that extracts the output signal of the clip circuit 74, and a subtracter 7 that subtracts the output signal of the clip circuit 74 from the image signal.
7, and a photometric integrator 56 that integrates the output signal of the n subtractor 77.

In FIG. 5, the image signal is applied from the input end of the photometric circuit 70 to the input ends of the integrator 51, the subtracter 62, and the subtracter 77.

The image signal inputted to the integrator 51 during the period td in which the signal level of the image signal shown by the solid line in FIG. The signal level is shown by the broken line in (a), and is subtracted from the image signal level by the subtracter 62, and is subtracted from the image signal level in FIG.
), the signal level is averaged over the portion where the signal level of the image signal is extremely high, and the clip circuit 7
In addition to 4, as shown in FIG. 6(b), the part of the potential higher than the clip potential VrGf of the reference power source 63 becomes an extracted analog signal, and as shown in FIG. It is subtracted from the image signal level, added to the photometric integrator 56, integrated by the photometric integrator 56 with a predetermined time constant, and output as a control signal for the AGC circuit, aperture control circuit, etc.

In this embodiment, the time constant of the integrator and the reference power supply 63
By appropriately selecting the clipping potential Vref, it is possible to apply the same image signal level to the photometric integrator 51 as in other periods even during the period td in which the signal level of the image signal is significantly high. continues to perform integral operation.

7 to 12 relate to the fourth embodiment of the present invention,
Figure 7 shows that the external endoscope is an electronic one using a television camera?
! A block diagram showing the configuration of the mirror device, FIG. 8 is an explanatory diagram of the endoscope display screen, FIG. 9 is a waveform diagram showing the f[signal in the case of FIG. 8, and FIG. 10 is the electronic endoscope device. 11 is an explanatory diagram showing the control of the photometric circuit,
FIG. 12 is a block diagram of the photometric circuit.

As shown in Fig. 7, an electronic endoscope device using a television camera (hereinafter referred to as a TV camera) as an external endoscope is as follows.
It is composed of an endoscope 11 using an image guide described later, a TV camera 12 detachably connected to the endoscope 11, and a main body unit 13 to which the endoscope 11 and TV camera 12 are connected. It has become so.

The endoscope 1111 includes, for example, an elongated insertion section that can be inserted into a body cavity, and a large-diameter operating section connected to the rear end of the insertion section. This family celebration &i
Inside the insertion section 11 is a light guide 1 that transmits illumination light.
4 is inserted, and the illumination light supplied from the main body unit 13 to the input end is transmitted to the output end, and is irradiated from the output end to the intrabody cavity site 5. The intrabody cavity site 5 illuminated by this illumination light is imaged by the objective lens 15 on the incident end of the image guide 16, and is guided through the image guide 16 to the eyepiece section provided at the rear end of the operating section. It is designed to be observed with the naked eye through an eyepiece lens 17. Furthermore, the aforementioned TV camera 12 is detachably connected to this eyepiece.

This TV camera 12 has an eyepiece lens 1 of the endoscope 11.
A lens 18 is provided at a position opposite to 7, and an image sensor 19, which is a COD, for example, is provided at the rear end of this lens 18. The above-mentioned image of the opposing internal region 5 is captured by the lens 1
8, the image is formed on the image carrying plane of the image sensor 19.

Further, a signal line is connected to the image pickup element 19, and this signal line is connected to the main body unit 13 in a detachable manner.

The main unit 13 includes a light source section 20 that illuminates the subject.
and an image signal processing unit 30 that outputs the video signal to the monitor 4.
Consisting of The light source unit 20 includes a lamp 21, an aperture 22 that adjusts the illumination light of the lamp 21, an aperture control circuit 23 that generates a control signal for variably controlling the aperture ratio of the aperture 22, and an image The image signal processing section 3 includes a photometry circuit 25 that measures the illuminance of light incident on the m-mechanical element 19 from the signal and generates a signal to the aperture control circuit 23;
0 is an AGC circuit 3 that amplifies the image signal to an appropriate level.
1, and a photometry circuit 3 that measures the illuminance of illumination light incident on the image sensor 19 from an image signal and generates a signal to the AGC circuit.
4, and a signal processing circuit 32 for performing various signal processing and outputting the processed signals to the monitor 4.

When the TV camera 12 is connected to the eyepiece of the endoscope $111 and the endoscope 11 is inserted into the body cavity, an image shown in the example of FIG. 8 can be observed on the monitor 4. FIG. 9 focuses on a certain horizontal scan 11B-8' of the image shown in FIG. 8, and shows the image signal level and the output level of the integrator 51 in the above-described embodiment in time series. As shown in FIG. 8, the image displayed on the monitor 4 has a high brightness in a substantially circular shape, for example, having the same shape as the end surface of the image guide 16, centered on the center of the screen.

Therefore, the image signal level sharply increases at the center of the horizontal position as shown by the solid line in FIG. 9, and therefore the output level of the integrator 51 becomes flat as shown by the broken line 1 in FIG. I end up. As a result, the image signal is not applied to the photometric integrator 56, and the brightness at the center of the screen increases, resulting in a self-flying state.

Therefore, in this embodiment, in order to avoid the above-mentioned situation, a regulating means is provided for regulating the action of the input limiting means for limiting the input to the photometric circuit.

The control means for controlling this regulating means will be explained using the electronic endoscope 1 shown in FIG. 10.

The main body unit 80 of the electronic endoscopic device includes, for example, an electronic scope 81 that is formed into an elongated shape so that it can be inserted into a body cavity.
Alternatively, a TV camera 86 connectable to the eyepiece of the endoscope 11 can be detachably connected.7゜Furthermore, the endoscope 11 can also be detachably connected. .

A light guide 6 for transmitting illumination light is inserted into the insertion section of the electronic scope 81, and transmits the illumination light supplied from the main body unit 80 to the input end to the output end, and from the output end to the intrabody cavity site 5. The direction is designed to irradiate. The light reflected from the intra-body cavity site 5 is focused by an objective lens 7, enters an image sensor 8, undergoes photoelectric conversion, becomes an image signal, and reaches a main body unit 80. Further, this electronic scope 81 is provided with a discrimination circuit 82 for controlling a photometry circuit, which will be described later.

The TV camera 86 is the same as the TV camera 12 described above, but is provided with a discrimination circuit 87 for controlling a photometry circuit, which will be described later.

The main body unit 80 includes a light source section 2o that supplies illumination light to the light guide 14 of the endoscope 11 or the light guide 6 of the electronic scope 81, and an image signal processing section 30 that outputs a video signal to the monitor 4. Become. The light source section 2
0 is the lamp 21 and the illumination light b1 of this lamp 21
an aperture 22 that adjusts the aperture ratio; an aperture υ control circuit 23 that generates a control signal for variable control of the aperture ratio of the aperture 22; The image signal processing section 30 includes a photometry circuit 26 that measures the illuminance of light incident on the lens 19 and generates a signal to the aperture control circuit 23;
an AGC circuit 31 that amplifies the image signal to an appropriate level;
A photometry circuit 35 measures the illuminance of the illumination light incident on the image sensor 8 of the electronic scope 810 or the image sensor 19 of the TV camera 86 from the image signal and generates a signal to the AGC circuit, and a photometry circuit 35 performs various signal processing and monitors. 4, and a signal processing circuit 32 for outputting to the signal processing circuit 4. Further, a discrimination circuit 82 provided in the electronic scope 81 or a discrimination circuit 87 provided in the TV camera 86 is connected to the photometry circuit 26.35.

The main body unit 8o includes the electronic scope 81 or the TV, as shown in FIGS. 11(a) and 11(b), for example.
A terminal 83 and a terminal 84 are provided in communication with the camera 86 . The terminal 83 is connected to the photometric circuit 26.35, and the terminal 84 is connected to a power source.

For example, as shown in FIG.
4 are electrically connected.

The discrimination circuit 87, as shown in FIG.
is in an open state with no connection.

Specifically, the photometric circuit 26.35 is comprised of a photometric circuit 90 shown in FIG. 12, for example. Note that the same functions as those in the above-described embodiment are designated by the same reference numerals, and the explanation thereof will be omitted.

The photometric circuit 90 includes an integrator 51, an adder 52, a bias power supply 53, a comparator 54, a switch 55, and a switch 91 that restricts the switch 55 from being controlled by the comparator 54. , a photometric integrator 56, and a pull-down resistor 97, which will be described later.

A control terminal for turning on and off the switch 91 is connected to the terminal 83 described above and is also grounded via the resistor 97.

The switch 91 is turned on when power is supplied to the terminal 83, a current flows through the resistor 97, a voltage is generated in the resistor 97, and the control terminal becomes "HT+". That is, as described above, the main unit 80 By connecting the electronic scope 81 to the photometry circuit 90, the photometry circuit 90 performs the same operation as in the first embodiment.

Further, the switch 91 is off when power is not supplied to the terminal 83 and the control terminal is "L".

That is, as mentioned above, the TV camera 8 is attached to the main unit 80.
6 is connected, the output signal of the comparator 54 is not applied to the switch 56, the switch 55 is always on, and the photometric integrator 56 continues to perform the integration operation.

That is, in this embodiment, when it is necessary to observe a low-brightness part of the screen, the effect is the same as in the first to third embodiments, and when it is necessary to observe a high-brightness part of the screen, the effect is the same as in the first to third embodiments. Appropriate photometry operation can be performed even in
There is an effect that the IJ of the low m degree part or the high brightness part can be easily switched.

FIG. 13 is a configuration diagram of a photometric circuit according to a fifth embodiment of the present invention. Note that the same reference numerals are used for parts that perform the same functions as those in the above-described embodiment, and the description thereof will be omitted.

The photometric circuit 100 of this embodiment includes an integrator 51 and an adder 5.
2, bias power supply 53, comparison ♂54, and switch 5
5, switch 91, photometric integrator 56, and resistor 97
and an AND circuit 103 that controls the switch 91 υ.

A first input terminal of the AND circuit 103 of the photometric circuit 100 is connected to the terminal 83 and grounded via the resistor 97. Further, a second input terminal of the AND circuit 103 is connected to an output terminal of a peak photometry/average photometry discrimination circuit (hereinafter referred to as a peak/average discrimination circuit) 102, which will be described later.

A momentary switch (hereinafter referred to as a switch) 101 provided, for example, on the exterior surface of the main unit 80 is connected to the input end of the peak/average discrimination circuit 102. In this peak/average discrimination circuit 102, when the switch 101 is pressed, the output signal at the output end alternately changes from L to 11"H", ie, II I 11 in the case of peak photometry and "H" in the case of average photometry. It is designed to be. Further, whether photometry is being performed using a peak value or an average value is displayed, for example, on a display section provided in the main unit 80 (not shown).

A control terminal for turning on and off the switch 91 is grounded to the output terminal of the AND circuit 103.

At the output end of the AND circuit 103, power is supplied to the terminal 83 connected to the first input end, current flows through the resistor 97, a voltage is generated in the resistor 97, and the first input end becomes '[bi'].
And since the output signal of the peak/average discrimination circuit 102 connected to the second input terminal becomes "H11", I
I 1'' becomes 11. Therefore, the switch 91 is connected to the output terminal of the AND circuit 103 connected to the control terminal. It is turned on by becoming 11. That is, as described above, the electronic scope 81 is attached to the main body unit 80.
is connected and average metering is selected,
This photometric circuit 90 performs the same operation as in the first embodiment.

Further, the output terminal of the AND circuit 103 is connected to the terminal 83 connected to the first JJ terminal, and no power is supplied to it, and the first input terminal is "L", or the output terminal connected to the second input terminal・If the output signal of the average discrimination circuit 102 is “L”
It becomes H. Therefore, the switch 91 is off because the output terminal of the AND circuit 103 connected to the control terminal is "ON". That is, when the TV camera 86 is connected to the main unit 80 or peak photometry is selected as described above, the output signal of the comparator 54 is output to the switch 5.
6, the switch 55 is always on, and the photometric integrator 56 continues to perform the integration operation.

Note that in this embodiment, the peak/average discrimination circuit 102
may be provided within the photometric circuit 100.

Further, the output terminal of the peak/average discrimination circuit 102 may be directly connected to the control terminal of the switch 910, so that even when the TV camera 86 is connected, it is possible to switch between peak photometry and average photometry.

That is, in this embodiment, even in the main unit 80 to which the electronic scope is connected, when it is necessary to observe a high brightness part of the screen, it is possible to easily switch between vA detection of the low 111 degree part or the high brightness part. There is an effect.

Note that when the present invention is applied to a photometry circuit of an electronic endoscope device connected to an electronic scope, the period Cd during which the image signal level from the treatment instrument becomes significantly high is 1 to 2 μs in the NTSG television system, and the integrator 510 Set the time constant to about 160μs
A good effect was obtained when set to .

In addition, high a! r! In order to obtain the same effect as in the above embodiment regardless of the size of the object, a means for varying the time constant of the integrator 51 of the photometric circuit may be provided.

Further, the switch 91 and the configuration related to the switch 91 described in the fourth embodiment or the fifth embodiment are used for controlling the switch 55 in the second embodiment, and for the subtracter 77 in the third embodiment. It may also be used to control the input end connected to the clip circuit 74.

Furthermore, although the embodiments described above have been described using an electronic endoscope device, they may be applied to other video camera devices.

[Effects of the Invention] As described above, according to the present invention, it is possible to easily remove the influence of a subject whose brightness is higher than the average brightness of the decoy screen on the subject of the m-color screen, and to adjust the brightness to suit the situation. This has the effect that a photographic screen can be obtained.

[Brief explanation of drawings]

1 and 2 relate to the first embodiment of the present invention, FIG. 1 is a configuration diagram of a photometric circuit, FIG. 2 is an explanatory diagram showing the operation of the photometric circuit, and FIGS. 3 and 4 are in accordance with the present invention. Regarding the second embodiment of the invention,
Fig. 3 is a block diagram of the photometric circuit, Fig. 4 is an explanatory diagram showing the operation of the photometric circuit, Figs. 5 and 6 relate to the third embodiment of the present invention, and Fig. 5 is a block diagram of the photometric circuit. , FIG. 6 is an explanatory diagram showing the operation of the photometric circuit, FIGS. 7 to 12 relate to the fourth embodiment of the present invention, and FIG. A block diagram showing the configuration of the endoscope device, FIG. 8 is an explanatory diagram of the endoscope display screen, FIG. 9 is a waveform diagram showing the image signal in the case of FIG. 8, and FIG. 10 is the electronic endoscope device. 11 is an explanatory diagram showing the configuration of the photometric circuit, FIG. 12 is a block diagram showing the configuration of the photometric circuit, and FIG.
14 is a block diagram showing a conventional example; FIG. 15 is an explanatory diagram without showing how a treatment instrument appears on an endoscope display screen; FIG. 16 is a waveform diagram showing the image signal in the case of FIG. 15. 50... Photometric circuit 51... Integrator 53...
・Bias power supply 54...Comparator 55...Switch 56...Integrator for photometry

Claims (1)

[Scope of Claims] A photometry circuit of an automatic gain control circuit or an automatic light control circuit of a video camera device, comprising: an integrating means for integrating an input image signal with a predetermined time constant; and an output of the integrating means and the input image signal. A photometry circuit for a video camera apparatus, comprising: a comparison means for comparing the output signal of the photometry circuit; and an input restriction means for limiting an input to the photometry circuit according to an output signal of the comparison means.