JP4464083B2 - Electronic endoscope device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electronic endoscope apparatus including a video scope having an image sensor. In particular, the present invention relates to brightness adjustment for detecting the brightness of a displayed subject image and maintaining the brightness of the subject image appropriately.
[0002]
[Prior art]
In a conventional electronic endoscope apparatus, when an image signal corresponding to a subject image is read from an image sensor in a video scope, a luminance value indicating the brightness of the subject image (hereinafter referred to as a representative luminance value) is calculated. Based on the difference between this luminance value and the reference luminance value indicating appropriate brightness, for example, the brightness is adjusted by opening and closing the aperture. It is also known to perform brightness adjustment using an electronic shutter function for an image sensor, and an electronic endoscope apparatus that uses both the electronic shutter function and light amount adjustment such as a diaphragm has been proposed (for example, , See Patent Document 1). When the electronic shutter function is used, the diaphragm is fixed at a substantially constant opening.
[0003]
[Patent Document 1]
JP 2002-119469 A (FIG. 1)
[0004]
[Problems to be solved by the invention]
In the case of adjusting the light amount by the diaphragm, the diaphragm is driven by an actuator such as a motor. The actuator has an operation characteristic that the follow-up is delayed with respect to a sudden change. Therefore, when the change in the brightness of the subject image changes abruptly, it is difficult to quickly adjust the brightness by opening and closing the aperture quickly. On the other hand, when the brightness is adjusted by the electronic shutter function, the amount of illumination light is suppressed to some extent in order to prevent burns on the inner wall of the organ due to light from the light source. Therefore, the brightness adjustment is always performed in a state where the light amount is insufficient.
[0005]
Therefore, an object of the present invention is to obtain an electronic endoscope apparatus or the like that can perform brightness adjustment quickly and appropriately even when the brightness of a subject image fluctuates rapidly.
[0006]
[Means for Solving the Problems]
An electronic endoscope apparatus according to the present invention includes a light source for illuminating a subject, a video scope having an image sensor that reads an image signal based on reflected light from the illuminated subject, and a subject based on the image signal. An electronic endoscope apparatus including a display unit that displays an image, a luminance signal is generated based on an image signal read from an image sensor, and the representative brightness of the entire subject image displayed on the display unit Representative luminance calculating means for calculating the luminance and brightness adjusting means for adjusting the brightness of the displayed subject image based on the representative luminance. At this time, the brightness adjustment is performed based on the difference amount from the reference brightness indicating the standard brightness.
[0007]
The brightness adjustment unit of the present invention includes a light amount adjustment unit that adjusts the amount of illumination light on the subject, and a charge accumulation time adjustment unit that adjusts the charge accumulation time for the image sensor. The light amount adjusting means has a diaphragm, for example, and adjusts the light amount to the subject by opening and closing the diaphragm. Alternatively, the intensity of light emitted from the light source may be adjusted. On the other hand, the charge accumulation time adjustment means can adjust a so-called electronic shutter speed, and adjusts the charge accumulation time based on, for example, a clock pulse signal of a CCD driver. The brightness adjusting unit controls the charge accumulation time adjusting unit according to the change amount of the difference amount. For example, the charge accumulation time may be adjusted according to the change amount of the difference amount.
[0008]
The operation of an actuator such as a motor is difficult to follow fast luminance fluctuations, but the electronic shutter speed can be switched at a very high speed compared to the actuator. Since the brightness is adjusted by adjusting the charge accumulation time for the luminance variation of the subject image, it is possible to quickly cope with the sudden luminance variation.
[0009]
The brightness adjustment means controls the amount of control proportional to the amount of difference between the representative brightness and the reference brightness that is the standard for brightness adjustment, and the control for eliminating the mismatch between the reference brightness and the representative brightness when the brightness is appropriate. The light amount adjusting means is preferably controlled according to the amount.
[0010]
For example, the brightness adjustment unit includes a differential compensator, an integral compensator, and a gain compensator in order to execute PID control. In this case, the charge accumulation time adjustment unit may be controlled according to the amount of change in the difference amount corresponding to the subject image obtained in the differential compensator. Further, the light amount adjusting means may be controlled in accordance with the control amounts output from the integral compensator and gain compensator.
[0011]
The brightness adjustment apparatus for an endoscope of the present invention is displayed based on a luminance signal generated from an image signal read from an image sensor of a videoscope that receives reflected light from a subject illuminated by light from a light source. The brightness of the displayed subject image based on the difference between the representative brightness calculating means for calculating the representative brightness indicating the brightness of the subject image and the reference brightness indicating the brightness of the subject image as a reference. Brightness adjustment means for adjusting the amount of light, and the brightness adjustment means includes a light amount adjustment means for adjusting the amount of light to the subject and a charge accumulation time adjustment means for adjusting the charge accumulation time for the image sensor. The charge accumulation time adjusting means is controlled in accordance with the amount of change.
[0012]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0013]
FIG. 1 is a block diagram of an electronic endoscope apparatus according to the first embodiment.
[0014]
The electronic endoscope apparatus includes a video scope 50 having a CCD (Charge-Coupled Device) 54 and a processor 10 for processing a signal read from the CCD 54, and a monitor 32 and a keyboard 34 for displaying a subject image. Are connected to the processor 10. The video scope 50 is detachably connected to the processor 10.
[0015]
When a lamp power switch (not shown) is turned on, power is supplied from the lamp power source 11 including the lamp control circuit 11A to the lamp (light source for illumination) 12, and thereby light is emitted from the lamp 12. The light emitted from the lamp 12 enters the incident end 51 </ b> A of the light guide 51 provided in the video scope 50 through the condenser lens 14. The light guide 51 is a bundle of ultrafine optical fibers that transmits light emitted from the lamp 12 to the distal end portion 60 of the video scope 50 in the vicinity of the observation site S. The light that has passed through the light guide 51 is emitted from the emission end. The light is emitted from 51B. As a result, light is irradiated to the observation region S that is the subject through the light distribution lens 52 that is an illumination lens, and the observation region S is illuminated.
[0016]
The light reflected at the observation site S passes through the objective lens 53 and reaches the light receiving area of the CCD 54, whereby an optical image of the observation site S is formed in the light receiving area of the CCD 54. In the present embodiment, a simultaneous single plate type is applied as a color imaging method, and yellow (Ye), cyan (Cy), magenta (Mg), and green (G) color elements are checked on the light receiving surface of the CCD. Complementary color filters (not shown) arranged in a line are arranged so as to correspond to the respective pixel positions in the light receiving region. In the CCD 54, an image signal composed of a plurality of pixel signals corresponding to the color of light transmitted through each color element of the complementary color filter is generated by photoelectric conversion, and an image signal for one frame or one field is generated at predetermined time intervals. The color difference lines are sequentially read out in accordance with the sequential method. The CCD driver 59 outputs a drive signal to the CCD 54 in order to read out the image signal based on the control signal from the scope control unit 56. In the present embodiment, the NTSC system is applied as a color television system, and image signals for one frame (one field) are sequentially read out every 1/30 (1/60) second interval, and an initial signal processing circuit. 55.
[0017]
The initial signal processing circuit 55 includes a preamplifier, a sample hold circuit, an image memory, an image processing circuit (none of which are shown), and the image signal input to the initial signal processing circuit 55 After processing, it is converted into a digital image signal and temporarily stored in an image memory. The digital image signal read from the image memory is sent to the image processing circuit, subjected to processing such as white balance adjustment and gamma correction, and then sent to the processor signal processing circuit 28 of the processor 10. Also, a luminance signal that is a luminance component of the image signal input to the initial signal processing circuit 55 is generated, converted into a digital signal by an A / D converter (not shown), and then the dimming circuit 23 of the processor 10. Sent to. Here, in accordance with the NTSC system, a luminance signal for one frame is sequentially sent every 1/30 (1/60) second interval.
[0018]
In the processor signal processing circuit 28, predetermined processing is performed on the image signal sent from the initial signal processing circuit 55. The processed image signal is output to the monitor 32 as a video signal (video signal) such as an NTSC composite signal, a Y / C separation signal (so-called S video signal), or an RGB separation signal, whereby a subject image is displayed on the monitor 32. It is.
[0019]
The system control circuit 22 includes a CPU 24, a ROM 25, and a RAM 26. The CPU 24 controls the entire processor 10, and controls signals to each circuit such as the dimming circuit 23, the lamp control circuit 11 A, and the processor signal processing circuit 28. Is output. In the timing control circuit 30, a clock pulse for adjusting a signal processing timing is output to each circuit in the processor 10, and a synchronization signal accompanying the video signal is sent to the processor signal processing circuit 28. The ROM 25 in the system control circuit 22 stores in advance a program for controlling the entire electronic endoscope apparatus.
[0020]
A diaphragm 16 that adjusts the amount of light applied to the subject S is provided between the incident end 51 </ b> A of the light guide 51 and the condenser lens 14, and opens and closes by driving the motor 18. In the present embodiment, the brightness of the subject image displayed on the monitor 32 is adjusted by the light control circuit 23 configured by a DSP (Digital Signal Processor). The dimming circuit 23 outputs a control signal for opening / closing the diaphragm 16 and a control signal for adjusting the brightness by the electronic shutter function based on the luminance signal sequentially sent from the video scope 50, the motor driver 20, and the scope control unit. 56 respectively. The motor driver 20 transmits a drive signal to the motor 18 based on the control signal. As a result, the motor 18 operates and the diaphragm 16 is driven to a predetermined opening. On the other hand, the CCD driver 59 outputs a drive signal at a predetermined timing in order to adjust brightness based on the control signal transmitted to the scope control unit 56. Thereby, the charge accumulation time in the CCD 54 is adjusted.
[0021]
In the video scope 50, a scope control unit 56 for controlling the entire video scope 50 and an EEPROM 57 in which data related to the video scope 50 are stored in advance are provided. The scope control unit 56 controls the initial signal processing circuit 55 and reads scope-related data from the EEPROM 57. When the video scope 50 is connected to the processor 10, data is transmitted and received between the scope control unit 56 and the system control circuit 22, and the data is sent to the system control circuit 22.
[0022]
The front panel 46 is provided with a setting switch 46A for setting the level of the reference luminance value Yr used as a standard in automatic light control. When the operator operates the switch, a signal corresponding to the operation is sent to the system control circuit 22. Sent to. The data of the reference luminance value Yr is temporarily stored in the RAM 26 and sent from the system control circuit 22 to the dimming circuit 23 as necessary.
[0023]
FIG. 2 is a block diagram of the dimming circuit 23.
[0024]
The dimming circuit 23 includes a differential compensator 23A, a gain compensator 23B, and an integral compensator 23C. The level of the luminance signal (representative luminance) Y indicating the brightness of the entire subject image is compared with the level of the reference luminance value Yr, and the difference amount is sent to the differential compensator 23A, gain compensator 23B, and integral compensator 23C, respectively. It is done. Here, the luminance level is classified into 256 levels and is set to any value from 0 to 255.
[0025]
The gain compensator 23B is a compensator for controlling the position of the motor 18. The gain compensator 23B is multiplied by a predetermined gain value (kp) to the input difference amount, and a control signal for determining the operation amount of the motor 18 is output. The When the level of the luminance signal Y is higher than the level of the reference luminance value Yr, a control signal is output so as to suppress the amount of light, and when the level of the luminance signal Y is lower than the level of the reference luminance value Yr, control is performed to increase the amount of light. A signal is output. On the other hand, the integral compensator 23B is a compensator that eliminates an error between the level of the luminance signal Y and the level of the reference luminance value Yr when the brightness of the subject image is appropriate and there is no luminance change, and is multiplied by a coefficient kls. The amount of difference integrated together is output from the integral compensator 23C. The output of the gain compensator 23B and the output of the integral compensator 23C are added and sent to the motor driver 20.
[0026]
The differential compensator 23A is a compensator that follows the change amount of the difference amount, that is, the change of the luminance signal Y. The input difference amount is differentiated and multiplied by the coefficient kD. The signal output from the differential compensator 23A is sent to the scope control unit 56. Based on the control signal output from the scope controller 56 based on the control signal output from the differential compensator 23A, the CCD driver 59 performs charge storage at a predetermined shutter speed corresponding to the luminance change. As shown, a clock pulse signal having a predetermined frequency is output. When the brightness of the subject image changes brightly, a clock pulse signal is output so that the electronic shutter speed decreases. On the other hand, when the brightness of the subject image changes darkly, a clock pulse signal is output so that the electronic shutter speed increases. Is done.
[0027]
As described above, according to the present embodiment, the dimming circuit 23 includes the differential compensator 23A, the gain compensator 23B, and the integral compensator 23C, and is based on the processing results of the gain compensator 23B and the integral compensator 23C. to together sends a control signal to the motor driver 20 to open and close the aperture 16 Te, control to CCD driver 59 via a scope controller 56 to adjust the electronic shutter speed based on the processing result of the differentiator compensator 23A Send a signal. The gain compensator 23 </ b> B and the integral compensator 23 </ b> C are connected to the motor driver 20 via an adder, and a control signal for opening and closing the diaphragm 16 is output to the motor driver 20. On the other hand, the differential compensator 23A is electrically connected to the scope controller 56, and when the brightness of the subject image changes abruptly, the electronic shutter speed is adjusted instead of opening and closing the diaphragm 16. In other words, the dimming circuit 23 performs a process based on PID control on the difference amount between the level of the luminance signal Y and the level of the reference luminance value Yr, and when the change amount of the difference amount is large, the differentiation is performed. The control by the compensator 23A becomes dominant, and the control by the gain compensator 23B becomes dominant as the amount of change in the difference decreases in the process in which the level of the luminance signal Y approaches the level of the reference luminance value Yr. Thus, when the level of the luminance signal Y matches the level of the reference luminance value Yr, the control by the integral compensator 23C becomes dominant, and the level of the luminance signal Y is maintained at the level of the reference luminance value Yr.
[0028]
The electronic shutter speed can be switched at a very high time interval of the field frequency. Therefore, when the amount of change in the difference between the level of the luminance signal Y and the level of the reference luminance value Yr is large, the charge accumulation amount in the CCD 54 is instantaneously changed, and the brightness of the subject image whose luminance has suddenly changed is set to an appropriate brightness. You can go back to it quickly. In addition, when the brightness of the subject image changes brightly, the scope tip 60 is often close to the observation unit. Since the electronic shutter speed shifts to a high speed, blurring of the displayed subject image is reduced.
[0029]
【The invention's effect】
As described above, according to the present invention, it is possible to quickly and appropriately adjust the brightness even when the brightness of the subject image fluctuates rapidly.
[Brief description of the drawings]
FIG. 1 is a block diagram of an electronic endoscope apparatus according to a first embodiment.
FIG. 2 is a block diagram of a dimming circuit.
[Explanation of symbols]
10 Processor 12 Lamp (light source)
16 Aperture 23 Dimming circuit 23A Differential compensator 23B Gain compensator 23C Integration compensator 50 Video scope 54 CCD (imaging device)

Claims (2)

A light source for illuminating a subject, a videoscope having an image sensor that reads an image signal based on reflected light from the illuminated subject, and a display unit that displays a subject image based on the image signal An electronic endoscope device,
Based on a luminance signal generated from an image signal read from the image sensor, a representative luminance calculating unit that calculates a representative luminance indicating the brightness of the subject image displayed on the display unit for each frame (field) period. When,
Based on the difference amount between the reference luminance indicating the brightness of the subject image to be the representative luminance and the reference, and a brightness adjusting means for adjusting the brightness of the object image to be displayed,
The brightness adjusting means is
A light amount adjusting means for adjusting the amount of illumination light to the subject, and a charge accumulation time adjusting means for adjusting a charge accumulation time for the image sensor,
The brightness adjusting means includes a differential compensator, a gain compensator, and an integral compensator for executing PID control, and the differential compensator calculates a control amount proportional to the amount of change in the difference amount to calculate the charge. Output to the accumulation time adjusting means, the gain compensator calculates a control amount proportional to the difference amount and outputs it to the light amount adjusting means, and further, a reference luminance when the integral compensator is appropriate in brightness And a control amount for eliminating the discrepancy between the representative luminance and the representative luminance is calculated and output to the light amount adjusting means.
The charge accumulation time adjusting means adjusts the charge accumulation time according to a control amount proportional to the change amount of the difference amount,
The electronic endoscope apparatus , wherein the light amount adjusting unit adjusts the illumination light amount according to a control amount proportional to the difference amount and a control amount for eliminating a mismatch between the reference luminance and the representative luminance . Based on the luminance signal generated from the image signal read from the imaging device of the videoscope that receives the reflected light from the subject illuminated by the light from the light source , the displayed subject image is displayed every frame (field) period . Representative luminance calculating means for calculating representative luminance indicating brightness;
Based on the difference amount between the reference luminance indicating the brightness of the subject image to be the representative luminance and the reference, and a brightness adjusting means for adjusting the brightness of the subject image displayed,
The brightness adjusting means is
A light amount adjusting means for adjusting the light amount to the subject, and a charge accumulation time adjusting means for adjusting a charge accumulation time for the image sensor,
The brightness adjusting means includes a differential compensator, a gain compensator, and an integral compensator for executing PID control, and the differential compensator calculates a control amount proportional to the amount of change in the difference amount to calculate the charge. Output to the accumulation time adjusting means, the gain compensator calculates a control amount proportional to the difference amount and outputs it to the light amount adjusting means, and further, a reference luminance when the integral compensator is appropriate in brightness And a control amount for eliminating the discrepancy between the representative luminance and the representative luminance is calculated and output to the light amount adjusting means.
The charge accumulation time adjusting means adjusts the charge accumulation time according to a control amount proportional to the change amount of the difference amount,
The brightness adjustment for an endoscope , wherein the light amount adjusting means adjusts the illumination light amount according to a control amount proportional to the difference amount and a control amount for eliminating a mismatch between the reference luminance and the representative luminance. apparatus.

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