JPH0549600A - Electronic endoscope apparatus - Google Patents

Abstract

PURPOSE:To obtain an image of high quality by setting a gain varying range of an AGC according to scopes to perform an automatic gain control for each scope on optimum operating conditions. CONSTITUTION:An image of an object is taken with solid image sensor 11 and is outputted adjusting the level of an output signal of the solid image sensor 11 to a optimum level with an AGC circuit 12. A maximum/minimum gain memory means 20 stores an allowable adjusting range of the output signal for each endoscope. A scope judging means 19 judges intrinsic information to each endoscope based on an output of a judgment signal generation means 18. A output signal level of the AGC circuit 12 is evaluated by an image evaluating means 14 and the allowable adjusting range is adjusted corresponding to the endoscope stored in the maximum/minimum memory means 20 based on an output of the image evaluating means 14 by a maximum/minimum gain computing means 17, a minimum gain control means 15, a maximum gain control means 16 and an AGC control means 13 and a control is performed to make the AGC circuit 12 operate within the allowable gain adjusting range.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called electronic endoscope apparatus for observing the inside of a body cavity using a solid-state image pickup device such as a CCD, and more specifically, it is automatic in accordance with the type of scope used. The present invention relates to an electronic endoscope apparatus that switches a variable gain range of a gain control means.

[0002]

2. Description of the Related Art An electronic endoscope apparatus has an optical fiber system that uses an optical fiber as an image transmission means, as compared with a conventional fiberscope.
Since the image quality is not deteriorated due to breakage of the fiber and the image recording is easy, it is widely used as the performance of the solid-state imaging device is improved.

In the endoscope apparatus, various types of scopes having an insertion portion corresponding to a target observation site are provided, and the electronic endoscope apparatus is no exception.

Further, in the electronic endoscope apparatus, in order to provide scopes of various kinds of outer diameters, a plurality of types of solid-state image pickup elements having different numbers of pixels are used according to the type of scope.

As described above, in the electronic endoscope apparatus,
Since the imaging conditions are different depending on the scope, when a plurality of types of scopes are used in the endoscope apparatus using one signal processing system, it is necessary to set the signal processing conditions according to the type of scope.

An example of a device for performing signal processing according to the type of scope is that disclosed in Japanese Patent Laid-Open No. 1-297043. In this device, the variable gain range of the automatic gain control circuit (hereinafter referred to as AGC) can be switched by the scope.

[0007]

However, in the above-mentioned conventional electronic endoscope apparatus, since the gain variable range of the AGC is determined depending on the type of scope, for example, the lamp light amount of the light source is lowered by long-term use. Or when combined with a small light source with a small amount of light
The gain of C may be insufficient.

Further, for example, if the maximum gain is determined by AGC so that the noise does not stand out too much even if a scope whose noise level is the upper limit of the standard is used, the gain is insufficient in many other scopes. Therefore, it is necessary to determine the variable gain range in consideration of variations in individual characteristics of the scope such as brightness and noise level.

The present invention has been made in view of these circumstances, and automatic gain control can be performed under optimum operating conditions for each scope by setting the gain variable range of the AGC according to the scope. It is an object of the present invention to provide an electronic endoscope device capable of obtaining a high quality image.

[0010]

An electronic endoscope apparatus according to the present invention includes an endoscope having an image pickup means, an endoscope discriminating means for discriminating information unique to each endoscope, and the image pickup means. Automatic gain control means for adjusting the level of the output signal to an appropriate level, storage means for storing the allowable adjustment range of the output signal of the image pickup means for each endoscope, and the output signal level of the automatic gain control means. Image evaluation means to be evaluated, and a gain for adjusting the allowable adjustment range stored in the storage means based on the output of the image evaluation means, and controlling the automatic gain control means to operate within the allowable gain adjustment range. And an adjustment range control means.

[0011]

The object image is picked up by the image pickup means, and the level of the output signal of the image pickup means is adjusted to an appropriate level and output by the automatic gain control means. Further, the storage unit stores the allowable adjustment range of the output signal of the image pickup unit for each endoscope. Then, the endoscope discriminating means discriminates the unique information for each endoscope. The image evaluation unit evaluates the output signal level of the automatic gain control unit, and the gain adjustment range control unit sets the allowable adjustment range corresponding to the endoscope stored in the storage unit based on the output of the image evaluation unit. The automatic gain control means is controlled to operate within this allowable gain adjustment range.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 7 relate to a first embodiment of the present invention, FIG. 1 is a block diagram showing a schematic configuration of a signal processing section of an electronic endoscope apparatus, and FIG. 2 is a diagram showing the overall configuration of the electronic endoscope apparatus. FIG. 4 is an explanatory diagram showing the AGC gain variable range, FIG.
1 is a block diagram showing a specific configuration example of the signal processing unit of FIG. 1, FIG. 5 is a circuit diagram showing a configuration example of a maximum / minimum gain control circuit, and FIG. 6 is a configuration example of a scope discrimination signal generation circuit and a scope discrimination circuit. FIG. 7 is a flow chart for explaining the maximum / minimum gain calculation.

As shown in FIG. 2, the electronic endoscope apparatus 1 includes
An electronic endoscope 2 having an image pickup means, a light source device 3 for supplying illumination light to the electronic endoscope 2, a signal processing device 4 for performing signal processing on the electronic endoscope 2, and this signal processing device. 4 and a monitor 5 for displaying a video signal output from the monitor 4. The electronic endoscope 2 is adapted to be connected to the light source device 3 via the connector 6 and to the signal processing device 4 via the connector 7, respectively. Is output to the signal processing device 4.

The schematic configuration of the signal processing section of the electronic endoscope 2 and the signal processing device 4 is as shown in FIG.
The electronic endoscope 2 includes a solid-state image sensor (S
ID) 13 is provided. A subject image of a target observation site is formed on the image pickup surface of the solid-state image pickup device 11 by an illumination optical system and an image pickup optical system (not shown), and is photoelectrically converted by the solid-state image pickup device 11 to be a video signal. Solid-state image sensor 1
1 is connected to the AGC circuit 12 in the signal processing device 4, and the video signal is input to the AGC circuit 12 and amplified. The output signal of the AGC circuit 12 is sent to the signal processing circuit of the next stage and is also input to the AGC control means 13 and the image quality evaluation means 14.

The AGC control means 13 sets A so that the video signal level of the output of the AGC circuit 12 becomes a predetermined level.
The AGC control signal for controlling the gain of the GC circuit 12 is generated, and this control signal is input to the AGC circuit 12 via the minimum gain control means 15 and the maximum gain control means 16.
The variable range of gain is set and controlled. The image quality evaluation means 14 extracts brightness, noise level, etc. from the video signal output from the AGC circuit 12, and outputs the evaluation signal to the maximum / minimum gain calculation means 17.

Further, the electronic endoscope 2 is provided with a discrimination signal generating means 18 for discriminating the type of scope. The discrimination signal generating means 18 is connected to the scope discrimination means 19 in the signal processing device 4, and the discrimination signal is discriminated by the discrimination means 19 to discriminate the type of scope. The output signal of the discrimination means 19 is input to the maximum / minimum gain calculation means 17.

The maximum / minimum gain calculating means 17 is connected to the maximum / minimum gain storing means 20 in which the maximum / minimum gain of the AGC for each connected scope is stored. The maximum / minimum gain calculation means 17 updates the maximum / minimum gain values stored in the maximum / minimum gain storage means 20 in accordance with the type of the connected scope and the output of the image quality evaluation means 14, and the minimum gain control. The means 15 outputs the minimum gain value and the maximum gain control means 16 outputs the maximum gain value.

Here, for example, as shown in FIG.
In the case where the gain of the AGC circuit 12 increases as the voltage of the control signal increases, the minimum gain control means 15 outputs the output below Emin even if the input AGC control voltage decreases below the voltage Emin corresponding to the minimum gain. Acts as a limiter so as not to go down. Similarly, the maximum gain control means 16 works so that the AGC control voltage does not rise above the voltage Emax corresponding to the maximum gain.

Next, a specific configuration example of the signal processing unit shown in FIG. 1 will be described with reference to FIG. The CCD 21 as a solid-state image sensor provided in the electronic endoscope 2 is connected to a CCD drive circuit 22 that drives the CCD 21 provided in the signal processing device 4. Also, C
The CD 21 is connected to the AGC circuit 23 and the dimming signal generation circuit 24 in the signal processing device 4,
The video signal read from the CCD 21 is supplied to these circuits. Dimming signal generation circuit 24
Outputs to the light source device 3 a dimming signal for setting an appropriate video signal level corresponding to the input signal level. This dimming signal controls the amount of illumination light so that an image that is easy to diagnose and inspect can be obtained when the usage conditions change, for example, when the usage conditions change from a close distance to the subject to a relatively long distance. It is designed so that it can be automatically set to an appropriate lighting intensity.

The AGC circuit 23 is connected to the signal processing circuit of the next stage, and is also connected to the integrating circuit 25 and the high pass filter (HPF) 26. The output terminal of the integrating circuit 25 is connected to the negative input terminal of the error generating circuit 27, and the video signal amplified by the AGC circuit 23 is integrated into the integrating circuit 2.
It is integrated in 5 and supplied to the error generating circuit 27. on the other hand,
A preset reference level EA is supplied to the positive input terminal of the error generating circuit 27.
The difference between and is output. The output end of the error generation circuit 27 is connected to the negative input end of the offset addition circuit 28. Further, the offset voltage EOS is supplied to the positive input terminal of the offset addition circuit 28, and the offset voltage EOS is added to the output of the error generation circuit 27,
It is supplied to the maximum / minimum gain control circuit 29. The control signal from the maximum / minimum gain control circuit 29 is A
The gain is controlled by being input to the GC circuit 23.

The maximum / minimum gain control circuit 29 is constructed, for example, as shown in FIG. The maximum / minimum gain control circuit 29 is provided with a first inverting amplifier 51 composed of resistors R1 and R2 and an operational amplifier A1, and a second inverting amplifier 52 composed of resistors R3 and R4 and an operational amplifier A2. Therefore, the input signal is inverted and amplified by the first inverting amplifier 51, then inverted and amplified by the second inverting amplifier 52, and output from the output end. A first limiter circuit 53 and a second limiter circuit 54 are provided in parallel between the first inverting amplifier 51 and the second inverting amplifier 52. The outputs are input to the first limiter circuit 53 and the second limiter circuit 54, and the outputs of these limiter circuits are input to the second inverting amplifier 5
2 is input.

The first limiter circuit 53 includes a resistor R
5, R6, R7, R8, operational amplifier A3, diode D
1 and D2, and the voltage Emax corresponding to the maximum gain of the AGC circuit 23 is applied to the operational amplifier A3 via the resistor R6. This first limiter circuit 5
No. 3 is set so that even if the level of the input signal becomes high, the signal is not output above Emax. That is, no voltage is generated at the point a unless the input signal exceeds Emax. This is because the diode D1 is reverse biased when the input level is equal to or lower than Emax. On the other hand, when the input level becomes equal to or higher than Emax, a voltage having a polarity opposite to that at the point b is generated at the point a by a voltage exceeding Emax. That is, the level of the input signal is Ema
When x is exceeded, the excess is offset and the output does not increase above Emax.

On the other hand, resistors R9, R10, R11, R1
A voltage Emin corresponding to the minimum gain of the AGC circuit 23 is applied to the input terminal of the operational amplifier A4 via the resistor R10 in the second limiter circuit 54 composed of 2, the operational amplifier A4, the diodes D3 and D4. It has become. In the second limiter circuit 54, when the input level becomes equal to or lower than Emin, a voltage having a polarity opposite to that of point b and smaller than Emin is generated at the point c, and the reduced voltage is offset to be equal to or less than Emin. The output does not decrease.

Further, in order to discriminate between different scope types, the electronic endoscope 2 is provided with a discrimination signal generating circuit 31, and the signal processing device 4 side is provided with a scope discrimination circuit 32. By the scope discrimination circuit 32, the discrimination signal generation circuit 3
The discrimination signal from 1 is discriminated, and the discrimination result is parallel I / O.
C via an interface (hereinafter referred to as PIO) 33
It is adapted to be input to the PU 34. FIG. 6 shows a configuration example of the discrimination signal generation circuit 31 and the scope discrimination circuit 32.

The discrimination signal generating circuit 31 is composed of a discrimination resistor Ra having connector pins P1 and P2 connected to both ends thereof. On the other hand, the pin receivers connected to the connector pins P1 and P2 provided in the determination circuit 32 are connected to the output end of the constant current source 55 and the ground, respectively. The constant current I output from the constant current source 55 flows through the resistor Ra, and the resulting voltage RaI is applied to one input end of one of the two comparators 56 and 57. Constant voltages V1 and V2 are applied to the other input terminals of these comparators 56 and 57, respectively, and the voltage R
Compared with aI. In this case, three types of scopes can be discriminated from the relationship between these voltages V1, V2 and RaI. Comparators 56 and 57 of the discrimination circuit 32
Each output of is input to the CPU 34 through the PIO 33. The discrimination signal generation circuit 31 also has information for discriminating each scope, and the discrimination result for each scope is input to the CPU 34.

The data bus 35 of the CPU 34 has a memory 36, a minimum gain output D / A converter 37, a maximum gain output D / A converter 38, and an image quality evaluation value input A / D.
The converter 39 is connected. The memory 36 stores values corresponding to maximum and minimum gains for each scope. Minimum and maximum gain output D / A converter 3
7 and 38 are Emax and E of the maximum / minimum gain control circuit 29.
Each is connected to the min input terminal. Further, the AGC circuit 23 is provided in the A / D converter 39 for inputting the image quality evaluation value.
The detection signal of the noise component detection circuit composed of the HPF 26 and the integration circuit 40 is input with the video signal from the.

Next, the operation of this embodiment will be described.
The insertion portion of the electronic endoscope 2 is inserted to a target observation site, and a subject image is captured. At this time, the CCD 21 is driven by the CCD drive circuit 22. The video signal read from the CCD 21 is input to the AGC circuit 23 and the dimming signal generation circuit 24 for controlling the light amount of the light source after the carrier is removed by a pre-process circuit (not shown). To be done. In the dimming signal generation circuit 24, a dimming signal corresponding to the input signal level is generated and supplied to the light source device, and the illumination light amount of the light source device is controlled so that the illumination intensity becomes appropriate.

The video signal amplified by the AGC circuit 23 is integrated by the integration circuit 25 to generate a signal corresponding to the brightness. This signal is input to the error generating circuit 27, and the difference from the preset reference level EA is output. That is, the output of the integrating circuit 25 is the reference level EA
A lower value gives a positive output, and a higher value than EA gives a negative output. This difference output is input to the offset addition circuit 28, the offset voltage EOS is added, and the maximum / minimum gain control circuit 29 is input.

On the other hand, the scope discriminating circuit 32 discriminates the scope type and individual scope, and the discriminating circuit 32
Is input to the CPU 34 through the PIO 33. The CPU 34 reads the maximum / minimum gain values stored in the memory 36 according to the connected scope, and H
The maximum and minimum gains are updated in consideration of the values corresponding to the noise components obtained by the PF 26 and the integrating circuit 40, and the AGC
The gain variable range of the circuit 23 is set. In FIG. 7, CPU3
4 shows a flowchart of an AGC control operation that is part of the operation of No.

When the maximum / minimum gain calculation task shown in FIG. 7 is called, in step S1 (hereinafter, the step is omitted and simply referred to as S1), scope type discrimination information is acquired from the PIO 33. Then, in S2, PI
Depending on the scope discrimination signal input via O33,
The data corresponding to the maximum / minimum gain stored in the corresponding area of the memory 36 is read. Next, in S3, the image quality evaluation value inputting A / D converter 39 performs A / D conversion to obtain a value corresponding to the noise component in the image.
Then, in S4, the difference (ΔEmax, ΔEmin) between the maximum and minimum gains is determined corresponding to the value corresponding to the noise component. For example, if there are many noise components, the maximum / minimum gain is lowered, and conversely, if there are few noise components, the difference data that increases the maximum / minimum gain is stored in advance in the memory 36, and A / A is stored. The difference data corresponding to the D-converted data is read. After that, in S5, new maximum / minimum gains (Emax, Emin) including the difference data are added.
) Is stored in the corresponding area of the memory 36, and S6
And the minimum and maximum gain output D / A converters 37, 3
In step 8, Emax and Emin are D / A converted and output. The above-described maximum / minimum gain calculation task may be called at any time, for example, every few seconds at all times, or at the time of image freeze (freeze) accompanying photography.

By the above maximum and minimum gain calculation tasks,
The maximum gain Emax and the minimum gain Emin are input to the maximum / minimum gain control circuit 29, and the variable gain range of the AGC circuit 23 is set so that automatic gain control is performed within this maximum / minimum gain range.

The CCD drive circuit 22 is connected to the scope discrimination circuit 32, and the CCD 21 can be driven according to the type of scope.

As described above, according to the present embodiment, the maximum / minimum gain of the AGC circuit is determined based on the noise component in the image signal and the values are stored for each connected scope. The maximum AGC gain can be set in a range where noise is not noticeable for each scope, and the best image quality can be obtained.

Further, by providing the maximum / minimum gain storage means, it is not necessary to adjust and reset the maximum / minimum gain every time the scope is connected, and the update period of the variable range of the AGC gain can be made long. Is possible. This makes it possible to easily set the optimum variable gain range for each scope without repeating unnecessary setting operations.

In this embodiment, the variable gain range is set for each of the maximum gain and the minimum gain. However, for example, only the maximum gain side may be variably set.

8 and 9 relate to the second embodiment of the present invention, FIG. 8 is a block diagram showing the configuration of the signal processing unit of the electronic endoscope apparatus, and FIG. 9 is a flow chart for explaining the maximum / minimum gain calculation. Is.

As shown in FIG. 8, in the second embodiment, the maximum and minimum gains are set by inputting the brightness level of the image signal when the aperture of the light source is fully opened. The same components as those in the first embodiment are designated by the same reference numerals and the description thereof will be omitted.

In the second embodiment, the A / D for inputting the image quality evaluation value
The HPF 26 of the first embodiment is connected to the input section of the converter 39.
And a noise component detection circuit composed of the integration circuit 40, instead of the low-pass filter (LPF) 41 and the integration circuit 42.
There is provided a brightness detection circuit for obtaining the brightness of the image constituted by. The dimming signal output from the dimming signal generation circuit 24 is sent to the light source device 3 and
It is input to one input terminal of the comparator 43. The reference voltage Vref is connected to the other input terminal of the comparator 43. The output terminal of the comparator 43 is the PIO 33.
Is input to the CPU 34 via.

Further, the CPU 34 is adapted to be supplied with an image freeze (freeze) instruction signal from a freeze switch or the like of the main body of the electronic endoscope 2 not shown.
Others are the same as those in the first embodiment.

Next, the operation of the electronic endoscope apparatus of this embodiment will be described. When the subject becomes a long distance, the dimming signal generation circuit 24 opens the diaphragm of the light source device 3 to increase the amount of emitted light, so that the level of the dimming signal increases. Further, when the subject is far away, the dimming signal becomes maximum and the diaphragm is fully opened. Here, the reference voltage Vref is preset to a voltage such that the output of the comparator 43 is inverted when the aperture of the light source device 3 is fully opened.

On the other hand, at the timing when the still image (freeze) is instructed from a freeze switch (not shown),
The maximum / minimum gain calculation task is called. This maximum
A flowchart of the minimum gain calculation is shown in FIG.

In FIG. 9, when the image is frozen, the CPU 34 obtains aperture information via the PIO 33 in S11. Here, if the diaphragm is fully open, the operation from S12 onward is performed, and if not, the variable gain range is not set and the task is ended. When the aperture is fully open, S12,
In S13, the scope type discrimination information is acquired as in the first embodiment, and the data corresponding to the maximum / minimum gain stored in the corresponding area of the memory 36 is read in accordance with the scope discrimination signal. Next, in S14, A for inputting the image quality evaluation value
A / D converter 39 performs A / D conversion to obtain data corresponding to the brightness of the image. Based on this brightness information, in S15 to S17, the difference between the maximum and minimum gains (ΔEmax, ΔEmin) is determined corresponding to the value corresponding to the brightness of the image, as in the first embodiment. The new maximum / minimum gain (Emax, Emin) including the difference data is stored in the memory 36.
Is stored in the corresponding area, and Emax and Emin are D / A converted by the minimum and maximum gain output D / A converters 37 and 38, respectively, and output. The variable gain range is set in this way. In this embodiment, the maximum / minimum gain is increased when the brightness data is small, and the maximum / minimum gain is decreased when the brightness data is large. The difference data is defined as follows.

As described above, according to this embodiment, the maximum and minimum gains of the AGC are set based on the brightness of the image at the maximum light amount, and therefore the optimum AGC gain including the combination with the light source device is set. The range can be set for each scope, and it is possible to display an image with good image quality.

[0044]

As described above, according to the present invention, since the variable gain range of the AGC can be set according to the scope, automatic gain control can be performed under optimum operating conditions for each scope. Therefore, there is an effect that a high quality image can be obtained.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a signal processing unit of an electronic endoscope apparatus.

FIG. 2 is a configuration diagram showing an overall configuration of an electronic endoscope apparatus.

FIG. 3 is an explanatory diagram showing a variable gain range of the AGC.

FIG. 4 is a block diagram showing a specific configuration example of a signal processing unit of the electronic endoscope apparatus according to the first embodiment of the present invention.

FIG. 5 is a circuit diagram showing a configuration example of a maximum / minimum gain control circuit.

FIG. 6 is a circuit diagram showing a configuration example of a scope discrimination signal generation circuit and a scope discrimination circuit.

FIG. 7 is a flowchart illustrating maximum / minimum gain calculation according to the first embodiment of the present invention.

FIG. 8 is a block diagram showing the configuration of a signal processing unit of the electronic endoscope apparatus according to the second embodiment of the present invention.

FIG. 9 is a flowchart illustrating maximum / minimum gain calculation according to the second embodiment of the present invention.

[Explanation of symbols]

 11 ... Solid-state image sensor 12 ... AGC circuit 13 ... AGC control means 14 ... Image evaluation means 15 ... Minimum gain control means 16 ... Maximum gain control means 17 ... Maximum / minimum gain calculation means 18 ... Discrimination signal generation means 19 ... Scope discrimination means 20 ... Maximum / minimum gain storage means

Claims (1)

[Claims] 1. An endoscope having an image pickup means, an endoscope discriminating means for discriminating information unique to each endoscope, and an automatic gain for adjusting a level of an output signal of the image pickup means to an appropriate level. Control means, storage means for storing the allowable adjustment range of the output signal of the image pickup means for each endoscope, image evaluation means for evaluating the output signal level of the automatic gain control means, and output for the image evaluation means A gain adjustment range control means for adjusting the allowable adjustment range stored in the storage means based on the above, and controlling the automatic gain control means to operate within the allowable gain adjustment range. Electronic endoscope device.