JP2003250761A - Automatic light regulator for endoscope and electronic endoscope unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To regulate the quantity of light for maintaining images of objects at proper brightness while controlling the generation of halation. <P>SOLUTION: In the electronic endoscope unit equipped with a video scope 50 having a CCD 54 and a processor 10, a stop 34 is provided between a histogram circuit 23, a light source lamp 12 and the emission end 51A of an optical fiber bundle 51. The histogram circuit 23 generates histogram data pertaining to the brightness of images of the object from image signals corresponding to the images of the object. The ratio of the generation of halation is calculated based on the histogram data to detect possible halation from the ratio of the generation of halation. When the halation is generated, the stop 34 is closed to reduce the quantity of light to the object while, when no halation is generated, the stop 34 is opened according to the brightness of the images of the object to increase the quantity of light. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an endoscope apparatus capable of observing an image of a predetermined portion by inserting an endoscope (scope) into an organ such as a stomach, and more particularly to the brightness of a subject image. The present invention relates to automatic light control for adjusting the amount of illumination light applied to an observation site so that the light intensity is constant.

[0002]

2. Description of the Related Art In a conventional endoscope apparatus, the brightness of a subject (luminance of the subject) is determined based on an image signal corresponding to a subject image.
Is detected, and the light amount of the illumination light is adjusted by comparing with a reference value indicating appropriate brightness of the subject. If the brightness value is larger than the reference value, the diaphragm is closed to reduce the light amount, and conversely, if the brightness value is smaller than the reference value, the diaphragm is opened to increase the light amount. As a value representing the brightness of the subject image to be compared with the reference value, an average luminance value indicating the average brightness of the entire subject,
Alternatively, the peak brightness value representing the maximum brightness is applied, and the operator can change the level of the reference value by operating the switch provided in the processor.

[0003]

When the light amount is adjusted by comparing the average luminance value with the reference value, halation (a state in which a part of the subject image appears in white) easily occurs,
It interferes with inspection and treatment. On the other hand, when the light intensity is adjusted by comparing the peak brightness value with the reference value, halation can be suppressed, but the observed subject image tends to be dark as a whole. Although the brightness problem can be solved to some extent by changing the setting of the reference value level, it is difficult for the operator to change the setting of the reference value level while operating the endoscope.
For this reason, it becomes difficult to always maintain the brightness of the subject at an appropriate brightness while performing a treatment or the like.

Therefore, an object of the present invention is to obtain an electronic endoscope apparatus and an automatic light control apparatus for an endoscope, which can adjust the light quantity for keeping the subject image at an appropriate brightness while suppressing the occurrence of halation. To do.

[0005]

An electronic endoscope apparatus according to the present invention is an electronic endoscope apparatus including a videoscope having an image pickup device and a processor to which the videoscope is connected. The image signal read from is processed and a video signal is output to a monitor or the like. The electronic endoscope apparatus of the present invention, in order to obtain histogram data regarding the brightness of a subject image, a histogram processing unit that performs a predetermined histogram process based on an image signal read from an image sensor, and a halation based on the histogram data. And a halation detecting means for detecting whether or not For example, based on the histogram data, a halation ratio indicating the ratio of the number of high-luminance pixels to the total number of pixels forming the subject image is calculated, and it is determined whether the halation ratio is a value other than 0. Halation should be detected.
The brightness value indicating the brightness of the subject image is set to any value in the range of 0 to 255 as the brightness level, for example. The high-brightness pixel is a pixel having a brightness value equal to or higher than the halation boundary brightness value, and the halation boundary brightness value is a brightness value serving as a threshold value (boundary value) for halation occurrence. For example, when the brightness value is in the range of 0 to 255, it is set to any value of 220 to 230. The electronic endoscope apparatus includes a light amount adjusting unit that adjusts the light amount of the light that illuminates the subject such that the subject image displayed on the monitor or the like has a brightness corresponding to the brightness level of the reference value. ,
The light amount is adjusted at predetermined time intervals based on the presence or absence of halation. The adjustment of the light amount may be performed, for example, in each reading period of the image signal for one frame.

The light quantity adjusting means according to the present invention reduces the light quantity when the halation is occurring and increases the light quantity at a constant time interval until just before the halation is occurring when the halation is not occurring. Go. For example, the light source unit is a light source such as a halogen lamp,
In the case of a configuration in which a diaphragm is provided between the entrance end of an optical fiber bundle provided in the videoscope, the light quantity is increased or decreased by opening and closing the diaphragm. Further, in the case where the light emitting diode is provided at the tip of the videoscope, the amount of light is increased or decreased by adjusting the amount of current sent to the light emitting diode. It is preferable that the constant time interval for increasing the light amount is matched with a predetermined time interval for adjusting the light amount.

Since the light amount is adjusted by detecting the presence or absence of halation instead of using the average luminance value, a subject image without halation can be displayed on a monitor or the like. In addition, the light intensity is increased at regular intervals until just before halation occurs, so the subject image is not kept dark as in the case of light intensity adjustment using the peak brightness value. , It is possible to always display a bright and easy-to-see subject image on the monitor.

When the subject image is dark, it is desirable to increase or decrease the amount of light according to the degree of darkness. Therefore, the electronic endoscope apparatus is preferably a dark part ratio calculating means for calculating a dark part ratio indicating a ratio of the number of pixels having a predetermined luminance or less to the number of all pixels forming the subject image, and a value of the dark part ratio. And a dark area ratio determining means for determining whether or not is greater than or equal to a reference dark area reference value. When the value of the dark part ratio is equal to or more than the value of the dark part reference ratio, the light amount adjusting unit increases the light amount more than when it is equal to or less than the dark part reference ratio. As a result, even when the subject image becomes dark, it is possible to immediately restore the proper brightness. However, the dark portion reference ratio represents a reference value for increasing the amount of light with respect to the entire subject image.

The automatic light control apparatus for an endoscope of the present invention, in order to obtain histogram data relating to the brightness of a subject image, a histogram processing means for performing a predetermined histogram process based on an image signal corresponding to the subject image, and a histogram processing means. Based on the data, a halation detecting unit that detects whether or not halation has occurred, and based on the presence or absence of halation, a predetermined amount of light that illuminates the subject so that the brightness of the subject image becomes appropriate brightness. And a light amount adjusting means for adjusting each time interval, the light amount adjusting means reduces the light amount when halation is occurring, and when halation is not occurring, a constant time interval until just before the halation occurs The feature is that the amount of light is increased by.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An electronic endoscope apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram of an electronic endoscope apparatus according to this embodiment. The electronic endoscope device is a device for performing inspections, operations, and the like on internal organs such as the stomach,
When the examination or the like is started, the videoscope is inserted into the body for photographing the observation site.

In the electronic endoscope apparatus, CC is used as an image pickup element.
Videoscope 50 having D54, and processor 1 for processing image signals sent from the videoscope 50
0 and a monitor 32 ′ for displaying a subject image is connected to the processor 10. The video scope 50 is detachably connected to the processor 10, and the keyboard 34 is connected to the processor 10.

The light emitted from the light source lamp 12 is incident on an incident end 51A of an optical fiber bundle 51 provided in the videoscope 50 via a condenser lens (not shown). The optical fiber bundle 51 is an optical fiber that transmits the light emitted from the lamp 12 to the tip side of the videoscope 50 having the observation site, and the light that has passed through the optical fiber bundle 51 is emitted from the emission end 51B. As a result, the observation site S is irradiated with light.

The light reflected at the observation area S reaches the light receiving surface of the CCD 54 through an objective lens (not shown), and an image of the observation area S is formed on the light receiving surface of the CCD 54. In the present embodiment, the single-plate simultaneous type is applied as a color imaging method, and yellow (Ye), cyan (Cy), magenta (Mg), and green (G) color elements are in a checkered pattern 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 pixels on the light receiving surface. In the CCD 54, an image signal of a subject image corresponding to a color passing through a complementary color filter is generated by photoelectric conversion, and an image signal for one frame or one field is sequentially read out at predetermined time intervals according to the color difference line sequential method. As a color television system, for example, N
The TSC system is applied, and image signals for one frame (one field) are sequentially read out at intervals of 1/30 (1/60) seconds and sent to the processor 10.

The signal processing circuit 20 of the processor 10 includes:
A CCD gain control circuit for controlling the gain of the image signal output from the CCD 54, a timing circuit for adjusting the timing (delay time) of reading the image signal, an R for controlling the R, G, B gains for white balance adjustment, A G and B gain control circuit, a gamma correction circuit for performing gamma correction, a color matrix circuit for generating a luminance signal, a color difference signal, and the like are included (all not shown). Various processes are performed on the image signal input to the signal processing circuit 20 in each circuit, and as a result, a video signal is generated. The generated video signal is output to the monitor 32 'as a video signal such as an NTSC composite signal, a Y / C separated signal (S video signal), an RGB separated signal, etc., whereby a subject image is displayed on the monitor 32'.

CPU (Central Processing Unit) 24
Controls the entire processor 10 and outputs a control signal to each circuit such as a signal processing circuit 20 including an IC chip, and a ROM (not shown) storing a program for performing light amount adjustment and the like. Have. The data rewritable EEPROM 57 is provided in the video scope 50.
Is provided, and data relating to the characteristics of the video scope 50 is stored in the EEPROM 57 in advance. When the video scope 50 is connected to the processor 10, the data stored in the EEPROM 57 is sent to the processor 10 and stored in the memory 26.

A series of panel switches 30 are provided on the front panel of the processor 10, and a process according to an operation on the panel switches 30 is executed. Also,
When a key operation is performed on the keyboard 34 to display character information such as patient information on the monitor 32 ', a signal corresponding to the operation of the keyboard 34 is input to the CPU 24,
CRTC (CRT controller) 22 based on the signal
A control signal is sent to. Then, a character signal corresponding to the key operation is output from the CRTC 22 and superimposed on the video signal. In addition, RTC (Real Time
Clock) 28, the date and time data is read by the CPU 24, and the character signal according to the current date and time is displayed on the CRT.
It is output from C22.

The incident end 51A of the light guide 51 and the light source 1
2 is provided with a diaphragm 34 for adjusting the amount of light irradiated to the subject S, and the diaphragm 34 is a motor 3
It is opened and closed by the drive of 3. The motor 33 is a stepping motor and is driven (rotated) according to the pulse signal sent from the aperture control circuit 32. Therefore, the drive amount of the diaphragm 34, that is, the change amount of the opening degree of the diaphragm 34 follows the pulse signal. In the present embodiment, the number of pulses required to drive the diaphragm 34 from fully open to fully closed is 240. The signal processing circuit 20 generates a luminance signal for one frame based on the image signal sent, and sends it to the histogram circuit 23. The histogram circuit 23 generates histogram data regarding the brightness of the subject image based on the transmitted luminance signal, and outputs the histogram data to the CPU 24. Then, a control signal is output to the aperture control circuit 32 based on the histogram data, and the aperture 34 is opened and closed so that the brightness of the subject image becomes appropriate brightness.

FIG. 2 is a diagram showing a main routine executed by the CPU 24 in the processor 10.

In step S101, the CPU 24 and variables are initialized. In step S102, a process regarding the panel switch 30 is performed, and when a predetermined switch is operated, the process for the switch is performed. In step S103, the process relating to the keyboard 34 is performed, and when a predetermined key is operated, the process corresponding to the key operation is performed.

In step S104, clock processing is performed, data corresponding to the date and time is read from the RTC 28, and the date and time are displayed on the monitor 32 '. In step S105, processing relating to the video scope 50 is performed. Then, in step S106, other processing is performed. Steps S102 to S106 are repeatedly executed until the main power supply of the processor 10 is turned off.

FIG. 3 is a diagram showing an interrupt routine for executing automatic light control processing. In this embodiment, 1/30
The automatic dimming process is performed every second by interrupting the main routine.

In step S201, the histogram circuit 23 generates data of a histogram (see FIG. 4) relating to the brightness of the subject image for one screen, and the CPU 24
Read by. Histogram monitor 32 '
The luminance signal of one frame sent from the signal processing circuit 20 (FIG. 1) to the histogram circuit 23 (FIG. 1) with the horizontal axis representing a possible luminance value of each pixel forming the subject image displayed in FIG. 4 is a graph in which the vertical axis represents the number (frequency) of pixels corresponding to each luminance value on the horizontal axis of all the pixels constituting the. In this embodiment, the brightness of the subject image is set to any value in the range of 0 to 255 as the brightness value. When step S201 is executed, the process proceeds to step S202.

In step S202, a variable vp1 representing the halation occurrence rate is calculated based on the histogram data.
A variable vp2 representing the high-luminance pixel ratio and a variable vdp representing the dark part ratio are calculated. Halation rate v
p1 represents the ratio of pixels having a luminance equal to or higher than the halation boundary luminance value (variable CB1) among all the pixels forming the subject image. The halation boundary brightness value CB1 is a brightness value at which halation is considered to occur on the screen of the monitor 32 ′ if it is equal to or greater than this value, and is set to 227, for example, here (see FIG. 4). The high-brightness pixel ratio vp2 indicates the ratio of pixels having a brightness equal to or higher than the high-brightness boundary brightness value (variable CB2) among all the pixels forming the subject image. The high-brightness boundary brightness value CB2 is a brightness value that is considered to be high brightness if it is greater than or equal to this value, and is set here to 197, for example (see FIG. 4). Dark area ratio vdp
Indicates the ratio of pixels having a luminance equal to or lower than the low luminance boundary luminance value (variable CD) among all the pixels forming the subject image. The low-luminance boundary luminance value CD is a luminance value that is considered to hinder observation if it is less than this value, and is set to 33 here, for example. When step S202 is executed, the process proceeds to step S203.

In step S203, the calculated halation ratio vp1 is the reference halation ratio (variable CP
1) It is determined whether or not it is greater than. The reference halation ratio CP1 is a ratio that serves as a reference for executing the light amount adjustment. If the halation ratio vp1 is larger than the reference halation ratio CP1, the light amount is reduced. Here, the reference halation ratio CP1 is set to 1% in consideration of maximizing the occurrence of halation. That is, the occurrence of halation is detected even if halation occurs in a very small part of the subject image. In step S203, the calculated halation ratio vp1
When it is determined that is larger than the reference halation ratio CP1, the process proceeds to step S215.

In step S215, a control signal for driving the diaphragm 34 by a predetermined amount is output to the diaphragm control circuit 32 so that the subject image has an appropriate brightness. In this embodiment, the driving amount of the diaphragm 34 is proportional to the rotation speed of the stepping motor, and the rotation amount of the stepping motor follows the number of pulses output from the diaphragm control circuit 32. As shown in FIG. 5, in the present embodiment, the number of pulses when the light amount is reduced is determined from the table T1 showing the correspondence relationship between the number of pulses and the high luminance pixel ratio vp2. Therefore, step S20
The number of pulses, that is, the driving amount of the diaphragm 34 is determined based on the value of the high-luminance pixel ratio vp2 calculated in 2. When step S215 is executed, the process proceeds to step S216, and the interrupt processing counter variable vc is set to 0.
The interrupt process counter variable vc is a variable for counting the number of interrupt processes. When step S216 is executed, the interrupt routine ends.

On the other hand, in step S203, the calculated halation ratio vp1 is the reference halation ratio C.
If it is determined that it is not larger than P1, that is, if halation has not occurred, the process proceeds to step S204, and 1 is added to the interrupt processing counter variable vc. Then, in step S205, the calculated dark area ratio vdp.
Is greater than the dark area reference ratio (variable CD1). The dark portion reference ratio CD1 indicates a dark portion ratio which is a standard for determining how much the light amount is increased. Here, the dark portion reference ratio CD1 is set to 15%. When the dark part ratio vdp is equal to or more than the dark part reference ratio CD1, the subject image is in an extremely dark state, and therefore, the process for increasing the light amount is performed in steps S211 to S2.
14 is executed. On the contrary, when the dark portion ratio vdp is smaller than the dark portion reference ratio CD1, the subject image is not in an extremely dark state, and thus the light amount increase is suppressed in steps S206 to S210.

In step S205, the dark area ratio vd
When it is determined that p is smaller than the dark part reference ratio CD1,
In step S206, the interrupt processing counter variable v
It is determined whether or not c is larger than the light amount increase start reference counter constant C1. Light amount increase start reference counter constant C1
Is a constant corresponding to the period from the execution of the light amount reduction in step S215 to the start of the light amount increase, and is set to 4 here. When it is determined that the interrupt process counter variable vc is not larger than the light amount increase start reference counter constant C1, the diaphragm 34 is in a hunting state because the diaphragm 34 has not been operated for a long time because the light amount has decreased. Therefore, the light intensity increase is not executed, and the interrupt routine ends as it is. On the other hand, when it is determined in step S206 that the interrupt process counter variable vc is larger than the light amount increase start reference counter constant C1, the process proceeds to step S207.

In step S207, it is determined whether the high-brightness pixel ratio (variable vp2) is larger than the high-brightness reference ratio CP2. The high-brightness reference ratio CP2 represents a high-brightness pixel ratio serving as a reference for determining the number of pulses with respect to the increase in the light amount. Here, the high luminance reference ratio CP2 is set to 30%. If it is determined that the high-brightness pixel ratio vp2 is higher than the high-brightness reference ratio CP2, step S20.
Go to 8. In step S208, a control signal is sent to the aperture control circuit 32 so that the aperture 34 is opened by a predetermined number of pulses. The number of pulses is set to a number that does not open the aperture 34 excessively, and is set to 1 here. on the other hand,
When it is determined in step S207 that the high-brightness pixel ratio vp2 is not larger than the high-brightness reference ratio CP2,
It proceeds to step S209. In step S209, the number of pulses is set to a value larger than that in step S208, and a control signal is sent to the aperture control circuit 32 so that the aperture 34 opens by the number of pulses. Here, the number of pulses is set to 2. When step S208 or step S209 is executed, the process proceeds to step S210,
The interrupt processing counter variable vc is the light amount increase presentation constant C2.
Is set to the value of. The light amount increase presentation constant C2 is a constant for indicating that the light amount has been increased, and is set to a value of 2 here. When step S210 is executed, the interrupt routine ends.

On the other hand, if it is determined in step S205 that the dark part ratio vdp is smaller than the dark part reference ratio CD1, the process proceeds to step S211. In step S211, it is determined whether or not the interrupt processing counter variable vc is 1. If it is determined that the interrupt processing counter variable vc is 1, it is not time has passed since the diaphragm 34 was driven to reduce the light amount in step S215, and therefore the diaphragm 34 is not driven to prevent hunting. The interrupt routine ends as it is. on the other hand,
In step S211, the interrupt processing counter variable v
If it is determined that c is not 1, the process proceeds to step S212.

In step S212, it is determined whether the dark portion ratio vdp is smaller than the light amount increasing reference ratio (variable CD2). The light amount increase reference ratio CD2 indicates a dark portion ratio that serves as a reference for determining the light amount increase amount. Here, the light amount increase reference ratio CD2 is set to 30%. When it is determined that the dark portion ratio vdp is smaller than the light amount increasing reference ratio CD2, the process proceeds to step S213. Step S21
In 2, the diaphragm 34 is opened by a predetermined number of pulses,
A control signal is sent to the aperture control circuit 32. The number of pulses is set to 8 here because the subject image is not extremely dark. On the other hand, when it is determined in step S212 that the dark portion ratio vdp is not smaller than the light amount increase reference ratio CD2, the process proceeds to step S214. Step S
At 214, a control signal is sent to the aperture control circuit 32 so that the aperture 34 is opened by a predetermined number of pulses. The number of pulses is set to 14 here in order to raise the brightness level of the subject image to some extent. When step S213 or step S214 is executed, the interrupt routine ends.

As described above, according to the present embodiment, the histogram data is generated in step S201, and in step S202, the halation occurrence rate vp1, the high-luminance pixel rate vp2, and the dark area rate vdp are calculated based on the histogram data. . Then, it is determined whether the halation is occurring or not by the halation occurrence rate vp1.
(S203). If halation occurs, the light amount is reduced (S215). On the other hand, when halation does not occur, the dark area ratio vd
It is determined whether p is smaller than the dark area reference ratio CD1 (step S205). When the dark portion ratio vdp is smaller than the dark portion reference ratio CD1, the diaphragm 34 is driven based on the pulse number that slightly increases the light amount (steps S208, 209). On the other hand, when the dark portion ratio vdp is not smaller than the dark portion reference ratio CD1, the diaphragm 34 is driven so that the light amount increases to some extent (steps S213 and S213).
214).

Further, in the present embodiment, when the light amount is not increased so much, the high-brightness pixel ratio vp2 and the high-brightness reference ratio CP2 are compared (step S207), and the value of the pulse number is divided into two levels by the comparison ( 1 pulse and 2 pulses) are set. Further, when increasing the light amount to some extent, the dark portion ratio vdp and the light amount increasing reference ratio CD2 are compared (step S212), and the value of the pulse number is divided into two stages by comparison (8 pulses and 1 pulse).
4 pulses) are set. However, when the number of pulses is set, the number of pulses is not limited to two, and may be set by subdividing.

Regarding the configuration for adjusting the light quantity, instead of adjusting the light quantity of the light incident on the optical fiber bundle by opening and closing the diaphragm, a light emitting diode is provided at the tip of the videoscope and the current supplied to the light emitting diode is controlled. You may adjust the light quantity of the light with which a to-be-photographed object is irradiated. Further, instead of the electronic endoscope device, the configuration for performing the above-described light amount adjustment may be applied to the endoscope light source device.

[0035]

As described above, according to the present invention, it is possible to perform the light amount adjustment for keeping the subject image at an appropriate brightness while suppressing the occurrence of halation.

[Brief description of drawings]

FIG. 1 is a block diagram of an electronic endoscope apparatus according to the present embodiment.

FIG. 2 is a diagram showing a main routine executed by a CPU in a processor.

FIG. 3 is a diagram showing an interrupt routine for executing automatic light control processing.

FIG. 4 is a diagram showing a histogram relating to the brightness of a subject image.

FIG. 5 is a diagram showing a table of a correspondence relationship between a high-luminance pixel ratio and the number of pulses.

[Explanation of symbols]

10 processors 24 CPU 32 Aperture control circuit 33 motor 34 Aperture 50 video scope 54 CCD (imaging device) vp1 halation rate vp2 High brightness pixel ratio vdp dark area ratio CD1 dark area reference ratio

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[Procedure amendment]

[Submission date] November 29, 2002 (2002.11.
29)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0012

[Correction method] Change

[Correction content]

In the electronic endoscope apparatus, CC is used as an image pickup element.
Videoscope 50 having D54, and processor 1 for processing image signals sent from the videoscope 50
0 and a monitor 32 ′ for displaying a subject image is connected to the processor 10. The video scope 50 is detachably connected to the processor 10, and a keyboard 34 'is connected to the processor 10.

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0017

[Correction method] Change

[Correction content]

A series of panel switches 30 are provided on the front panel of the processor 10, and a process according to an operation on the panel switches 30 is executed. Also,
When a key operation is performed on the keyboard 34 to display character information such as patient information on the monitor 32 ', a signal corresponding to the operation of the keyboard 34' is input to the CPU 24, and a CRTC (CRT controller) is based on the signal.
A control signal is sent to 22. Then, a character signal corresponding to the key operation is output from the CRTC 22 and superimposed on the video signal. In addition, RTC (RealTi
The date and time data is read from the meClock) 28 by the CPU 24, and the character signal according to the current date and time is CR.
It is output from TC22.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0020

[Correction method] Change

[Correction content]

In step S101, the CPU 24 and variables are initialized. In step S102, a process regarding the panel switch 30 is performed, and when a predetermined switch is operated, the process for the switch is performed. In step S103, the keyboard 34 '
Is performed and a predetermined key is operated,
The process corresponding to the key operation is executed.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0027

[Correction method] Change

[Correction content]

On the other hand, in step S203, the calculated halation ratio vp1 is the reference halation ratio C.
If it is determined that it is not larger than P1, that is, if halation has not occurred, the process proceeds to step S204, and 1 is added to the interrupt processing counter variable vc. Then, in step S205, the calculated dark area ratio vdp.
Is larger than the dark area reference ratio (constant CD1). The dark portion reference ratio CD1 indicates a dark portion ratio which is a standard for determining how much the light amount is increased. Here, the dark portion reference ratio CD1 is set to 15%. When the dark part ratio vdp is equal to or more than the dark part reference ratio CD1, the subject image is in an extremely dark state, and therefore, the process for increasing the light amount is performed in steps S211 to S2.
14 is executed. On the contrary, when the dark portion ratio vdp is smaller than the dark portion reference ratio CD1, the subject image is not in an extremely dark state, and thus the light amount increase is suppressed in steps S206 to S210.

[Procedure Amendment 5]

[Document name to be amended] Statement

[Name of item to be corrected] 0030

[Correction method] Change

[Correction content]

On the other hand, if it is determined in step S205 that the dark portion ratio vdp is larger than the dark portion reference ratio CD1, the process proceeds to step S211. In step S211, it is determined whether or not the interrupt processing counter variable vc is 1. If it is determined that the interrupt processing counter variable vc is 1, it is not time has passed since the diaphragm 34 was driven to reduce the light amount in step S215, and therefore the diaphragm 34 is not driven to prevent hunting. The interrupt routine ends as it is. on the other hand,
In step S211, the interrupt processing counter variable v
If it is determined that c is not 1, the process proceeds to step S212.

[Procedure correction 6]

[Document name to be amended] Statement

[Correction target item name] 0031

[Correction method] Change

[Correction content]

In step S212, it is determined whether the dark portion ratio vdp is smaller than the light amount increasing reference ratio (constant CD2). The light amount increase reference ratio CD2 indicates a dark portion ratio that serves as a reference for determining the light amount increase amount. Here, the light amount increase reference ratio CD2 is set to 30%. When it is determined that the dark portion ratio vdp is smaller than the light amount increasing reference ratio CD2, the process proceeds to step S213. Step S21
In 3, the diaphragm 34 is opened by a predetermined number of pulses,
A control signal is sent to the aperture control circuit 32. The number of pulses is set to 8 here because the subject image is not extremely dark. On the other hand, when it is determined in step S212 that the dark portion ratio vdp is not smaller than the light amount increase reference ratio CD2, the process proceeds to step S214. Step S
At 214, a control signal is sent to the aperture control circuit 32 so that the aperture 34 is opened by a predetermined number of pulses. The number of pulses is set to 14 here in order to raise the brightness level of the subject image to some extent. When step S213 or step S214 is executed, the interrupt routine ends.

Claims (3)

[Claims] 1. An electronic endoscope apparatus comprising a videoscope having an image pickup device and a processor to which the videoscope is connected, wherein the electronic endoscope device is read from the image pickup device in order to obtain histogram data relating to the brightness of a subject image. Histogram processing means for performing a predetermined histogram processing based on the image signal to be displayed, halation detection means for detecting whether or not halation is occurring based on the histogram data, and a subject image based on the presence or absence of halation. And a light amount adjusting means for adjusting the light amount of the light for illuminating the subject at predetermined time intervals so that the brightness becomes appropriate brightness, and the light amount adjusting means reduces the light amount when halation occurs. If there is no halation, a fixed time interval is applied until just before the halation occurs. An electronic endoscope device characterized by increasing the amount of light. 2. A dark area ratio calculating means for calculating a dark area ratio indicating a ratio of pixels having a luminance equal to or lower than a predetermined brightness in the entire subject image, and a value of the dark area ratio is equal to or larger than a reference dark area reference ratio. Dark area ratio determining means for determining whether or not, when the value of the dark area ratio is greater than or equal to the reference dark area reference ratio, the light amount adjusting means, when the dark area reference ratio is less than The electronic endoscope device according to claim 1, wherein the amount of light is increased more than that of the electronic endoscope device. 3. Histogram processing means for performing predetermined histogram processing based on an image signal corresponding to the subject image to obtain histogram data relating to the brightness of the subject image, and halation is generated based on the histogram data. Halation detecting means for detecting whether or not there is light, and light quantity adjusting means for adjusting the light quantity of the light for illuminating the subject at predetermined time intervals so that the brightness of the subject image becomes appropriate brightness based on the presence or absence of halation. Wherein the light amount adjusting means decreases the light amount when halation is occurring, and increases the light amount at a constant time interval until just before halation occurs when halation is not occurring. An automatic light control device for endoscopes.