JP4555056B2 - Electronic endoscope device - Google Patents

Description

  The present invention relates to an electronic endoscope apparatus including a video scope having an image sensor, and more particularly, to a brightness adjustment process for a subject image.

In an electronic endoscope device, in order to maintain a subject image displayed on a monitor or the like with an appropriate brightness, the amount of illumination light to the subject is adjusted by opening / closing control of the aperture, or the subject is made using an electronic shutter function. Adjust the image brightness. When using the electronic shutter function, a configuration is known in which a diaphragm is provided for adjusting the amount of illumination light. For example, when the light amount becomes insufficient due to the change of the light source lamp over time, the diaphragm is driven to increase the light amount (see Patent Document 1). On the other hand, in order to prevent heat generation at the distal end of the scope, a dimming process is performed when the diaphragm is continuously opened for a predetermined time or more (see Patent Document 2).
Japanese Patent No. 3343278 JP 2002-282207 A

  Heat generation at the distal end of the scope should be avoided as much as possible in consideration of the influence on the circuit provided at the distal end and the particularity of the scope distal end being fed into the human body. Therefore, it is not practical to use the illumination light amount that can be obtained as much as possible by the illumination light of the light source lamp, and the diaphragm, the shielding plate, etc. are arranged in the optical path so as to be less than the predetermined light amount, and the illumination light amount is suppressed in advance. . As a result, when observing and photographing a wide part of the internal space such as the stomach, the amount of illumination is insufficient, making observation difficult, and blurring occurs in the photograph. In Patent Document 1, it is possible to cope with a change with time over the lifetime of the lamp, but it is not possible to quickly cope with a temporal change in light quantity (excessive or insufficient light quantity) due to the position of the scope tip.

  The electronic endoscope apparatus according to the present invention is an electronic endoscope apparatus including a video scope having an image sensor, and the video scope is connected to a processor or a light source device. The electronic endoscope apparatus includes a light source that illuminates a subject, and a luminance calculation unit that calculates a luminance value based on an image signal corresponding to the subject image read from the image sensor. For example, the luminance calculation means may sequentially calculate the luminance value based on image signals read out from the image sensor at predetermined time intervals in accordance with the television standard or the like. The luminance value may be a value representing the representative brightness of the subject image, and for example, an average luminance value is calculated. The electronic endoscope apparatus can adjust the brightness by the electronic shutter function. The brightness of the subject image displayed on the display device or the like is set to a predetermined value by adjusting the charge accumulation time in the image sensor according to the calculated luminance value. Brightness adjusting means for adjusting at time intervals is provided. If the amount of illumination light is insufficient, the charge accumulation time becomes longer, and if the amount of illumination light increases more than necessary, the charge accumulation time becomes shorter. The brightness value may be adjusted at a time interval (for example, 1/60 second) according to the television standard.

  The electronic endoscope apparatus of the present invention includes a light amount control unit different from the brightness adjustment unit, and the light amount control unit sets the upper limit set value based on the illumination state in which the light amount needs to be increased. If it exceeds (exceeds) over the first allowable time, the illumination light quantity is increased. On the other hand, if the charge accumulation time exceeds (below) the second allowable time or more than the lower limit set value based on the lighting state where the light quantity needs to be reduced, that is, if the charge accumulation time is smaller than the lower limit set value, the light quantity control is performed. Means reduce the amount of illumination light.

The upper limit set value is a value based on an illumination state in which the amount of light needs to be increased. For example, the upper limit value is close to the upper limit side (side where the amount of light is insufficient) having a large value in the charge accumulation time range in which the amount of light is not increased. Value is set. For example, the upper limit setting value may be set to a value that affects blurring of still image shooting (for example, 1/125 sec = 8.0 msec). The first allowable time is set to 1 second or several seconds, for example. On the other hand, the lower limit set value is a value based on an illumination state in which the light amount needs to be reduced. For example, the lower limit side (the side on which the light amount is sufficient) where the value of the charge accumulation time range in which the light amount does not need to be reduced is small. A value close to the value is set. For example, the lower limit set value may be set to a value (for example, 1/4000 sec = 0.25 msec) in consideration of preventing heat at the scope tip. The second allowable time may also be set to 1 second or several seconds.

  If the state where the amount of light is insufficient continues for a certain period, it is detected that the state where the charge accumulation time exceeds the upper limit set value (exceeds) exceeds the allowable time, and the amount of light is increased. As a result, the observation site is irradiated while the illumination light quantity of the light source is maximally utilized. Since the state where the charge storage time is long does not continue, no blur occurs even when timely shooting is performed. Further, it is detected that the state where the charge accumulation time exceeds the lower limit set value (below) exceeds the allowable time, and the amount of light is reduced. As a result, the burn at the observation site and the heat generation at the distal end of the scope are suppressed although it is a minor problem compared to this.

  Regarding the brightness adjustment by the electronic shutter function, the brightness adjustment means may be configured only inside the video scope, or may be provided in the processor (light source device). Further, the light quantity control means may be configured by a diaphragm or the like and provided in a processor (light source device), or may be provided in a video scope by being configured by an LED or the like. For example, the light quantity control means includes a stop arranged in the optical path of the illumination light and a stop drive means for driving the stop.

  In order to prevent the observer from noticing that the light amount has changed, it is desirable that the light amount control means change the illumination light amount step by step when increasing or decreasing the illumination light amount.

  After increasing the illumination light amount, the light amount control means may return the illumination light amount before the increase if the charge accumulation time exceeds the lower limit boundary value for the third allowable time or longer (below). In addition, the light amount control means may return the illumination light amount to the state before the decrease when the charge accumulation time exceeds the upper limit boundary value for the fourth allowable time or longer after the illumination light amount is decreased. Good. The lower limit boundary value is set smaller than the upper limit set value, and the upper limit boundary value is set larger than the lower limit set value.

  The brightness adjustment apparatus for an endoscope of the present invention is calculated by luminance calculation means for calculating a luminance value based on an image signal corresponding to a subject image read from an image pickup device of a videoscope by illuminating the subject. By adjusting the charge accumulation time in the image sensor according to the brightness value, the brightness adjustment means that adjusts the brightness of the subject image at predetermined time intervals, and the upper limit set value based on the illumination state that needs to increase the amount of light When the accumulation time exceeds (exceeds) the first allowable time or more, the illumination light quantity is increased, while the charge accumulation time is set to the second lower limit set value based on the illumination state where the light quantity needs to be reduced. It is characterized by comprising a light quantity control means for reducing the illumination light quantity when it exceeds (below) the permissible time.

  A program for an electronic endoscope apparatus according to the present invention includes a luminance calculation unit that calculates a luminance value based on an image signal corresponding to a subject image read from an image pickup device of a videoscope by illuminating the subject, and a calculated luminance By adjusting the charge accumulation time in the image sensor according to the value, the brightness adjustment means for adjusting the brightness of the subject image at predetermined time intervals, and the upper limit set value based on the illumination state that needs to increase the amount of light If the time exceeds (exceeds) the first permissible time or more, the amount of illumination light is increased while the lower limit set value based on the illumination state where the light amount needs to be reduced is the second permissible charge accumulation time. When it exceeds (below) for more than time, the light quantity control means for reducing the illumination light quantity is made to function.

  According to the present invention, even when the brightness is adjusted using the electronic shutter function, the affected part can be appropriately observed and photographed without being affected by a situation where the amount of illumination light is insufficient or the influence of the heat at the distal end of the scope. .

  Hereinafter, an electronic endoscope apparatus according to an embodiment of the present invention will be described with reference to the drawings.

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

  The electronic endoscope apparatus includes a video scope 50 having a CCD 54 and a processor 10 that processes an image signal read from the CCD 54, and a monitor 32 and a keyboard 34 that display a subject image are connected to the processor 10. The video scope 50 is detachably connected to the processor 10.

  When a lamp lighting switch (not shown) is operated and turned on, power is supplied from the lamp power source 11 including the lamp control unit 11A to the light source lamp 12. The light emitted from the light source 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 an optical fiber bundle that transmits light emitted from the light source lamp 12 to the distal end side of the video scope 50. Light that has passed through the light guide 51 is emitted from the emission end 51B, and is a light distribution lens that is a diffusion lens. The observation site S is irradiated with light through 52.

  The light reflected at the observation site S passes through the objective lens 53 and reaches the CCD 54, whereby a subject image of the observation site S is formed on the light receiving surface of the CCD 54. In this embodiment, a single plate simultaneous 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 pixels on the light receiving surface. In the CCD 54, the image signal of the subject image corresponding to the color passing through the complementary color filter is generated by photoelectric conversion, and the image signal for one frame or one field is sequentially read according to the color difference line sequential method at every predetermined time interval. For example, the NTSC system is applied as a color television system, and image signals for one frame (one field every 1/60 second interval) are sequentially read out every 1/30 second interval, and the AGC ( The signal is sent to the signal processing circuit 55 via Auto Gain Control (not shown here).

  In the signal processing circuit 55, amplification processing, separation processing for separating luminance signals and color signals, matrix calculation for generating R, G, B signals, white balance adjustment, gamma correction, luminance, color difference signal generation processing, and the like are executed. . A video signal is generated by performing various processes on the image signal input to the signal processing circuit 55 and sent to the processor 10. On the other hand, a luminance value indicating the brightness of the subject image is calculated based on the input image signal and sent to the scope controller 56. Further, a CCD drive circuit that outputs a drive signal at a predetermined timing is provided to drive the CCD 54.

  In the processor signal processing circuit 28, predetermined processing is performed on the video signal transmitted from the signal processing circuit 55. The processed video signal is output to the monitor 32 as a video signal such as an NTSC composite signal, a Y / C separation signal (S video signal), or an RGB separation signal, whereby a subject image is displayed on the monitor 32.

  A system control circuit 22 including a CPU 24 controls the entire processor 10 and outputs a control signal to each circuit such as the lamp control unit 11A of the lamp power supply 11, the motor driver 20, and the processor signal processing circuit 28. 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 stores a program related to processor control in advance, and the RAM 26 stores data sent from the video scope 50.

  In the video scope 50, a scope control unit 56 that controls the entire video scope 50 and a data rewritable EEPROM 57 are provided, and a program related to the scope control is stored in the ROM 58 in the scope control unit 56. The scope control unit 56 reads data from the EEPROM 57 and controls the signal processing circuit 55. When the video scope 50 is connected to the processor 10, timely data is transmitted and received between the scope control unit 56 and the system control circuit 22, and from the scope control unit 56 to the system control circuit 22 as necessary, or the system control circuit. Data is transmitted from 22 to the scope control unit 56.

  The video scope 50 can execute the brightness adjustment processing of the subject image using the electronic shutter function, and the signal processing circuit 55 generates a luminance value indicating the brightness of the subject image based on the image signal. To the scope control unit 56. A control signal is sent from the scope control unit 56 to the signal processing circuit 55 in order to control the electronic shutter speed based on the detected luminance value and a reference value indicating appropriate brightness. Based on this control signal, a drive signal for determining the charge accumulation time in the CCD 54 is output from the signal processing circuit 55 to the CCD 54.

  Between the light source lamp 12 and the incident end 51 </ b> A of the light guide 51, a diaphragm 16 that adjusts the amount of illumination light in three stages is provided. The diaphragm 16 is driven by a motor 18 and rotates based on a drive signal from the motor driver 20 so that the diaphragm 16 blocks a part of the optical path. Here, the illumination light amount when increasing the light amount is defined as Q1, the normal illumination light amount is defined as Q2, and the illumination light amount when decreasing the light amount is defined as Q3. The diaphragm 16 is positioned so that the light quantity Q1 is 1.5 times the light quantity Q2 and the light quantity Q3 is 2/3 times the light quantity Q2. Here, the light amount is a light amount incident on the incident end 51 </ b> A of the light guide 51.

  FIG. 2 is a flowchart showing overall control processing executed by the system control circuit 22 of the processor 10.

  In step S101, the aperture position and variables are initialized. Here, the aperture position is set to a position where the light quantity becomes Q2 (normal illumination light quantity). The light quantity variable q corresponding to the light quantity is set to q = 2. In step S102, processing related to the connection of the video scope 50 is executed. In step S 103, communication processing with the video scope 50 is executed, and data corresponding to the charge accumulation time of the CCD 54 in the brightness adjustment processing is sent from the video scope 50. In step S104, processing related to the keyboard 34 is executed. In step S105, processing for the panel switch on the front panel of the processor 10 is executed, and in step S106, other processing is executed. While the power of the processor 10 is ON, steps S102 to S106 are repeatedly executed.

  3 and 4 are flowcharts showing the light amount control processing executed in the system control circuit 22 of the processor 10. FIG. 5 is a diagram showing the position of the diaphragm and the value of the light quantity variable. FIG. 6 is a diagram illustrating a correspondence relationship between the upper limit set value ET1, the lower limit boundary value ET2, the upper limit boundary value ET3, the lower limit set value ET4, and the illumination light amounts Q1 to Q4 of the charge accumulation time. In accordance with the NTSC system, the brightness adjustment process is executed by interrupting the entire process of FIG. 2 at 1/60 second intervals.

  Note that the scope control unit 56 of the video scope 50 receives a luminance value indicating the brightness of the subject image from the signal processing circuit 55. Then, the brightness value is compared with a reference value indicating the appropriate brightness of the subject image, and an exposure time, that is, a charge accumulation time et is set. The luminance value of the subject image is calculated as an average luminance value, and the luminance value is set to an integer value of 0 to 255 so that the brightness of the subject image is represented by 256 levels of luminance levels. Here, the charge accumulation time et is set in a range of 0 to 17 msec (= 1/60 sec). When the luminance value is larger than the reference value, the charge accumulation time et is reduced by a predetermined fluctuation time Δt (> 0) in order to shorten the charge accumulation time. On the other hand, when the luminance value is smaller than the reference value, a predetermined fluctuation time Δt is added to the charge accumulation time et in order to lengthen the charge accumulation time. The set charge accumulation time et is transmitted to the signal processing circuit 55, and the CCD 54 is driven based on the transmitted charge accumulation time et. Further, the charge accumulation time et data is transmitted to the system control circuit 22 of the processor 10.

  In step S201, it is determined whether or not the value of the light quantity variable q is 1. The light quantity variable q is a variable corresponding to the light quantity incident on the incident end 51A of the light guide 51, that is, the illumination light quantity, q = 1 when the light quantity is Q1, q = 2 when the light quantity is Q2, and q = 3 when the light quantity is Q3. Determined. The amount of illumination light is discriminated based on the value of the light amount variable q. Here, it is determined whether or not the amount of illumination light is larger than the normal amount of illumination light.

  If it is determined in step S201 that the light quantity variable q is 1, the process proceeds to step S202. In step S202, it is determined whether or not the charge accumulation time et is longer than the lower limit boundary value ET2. The lower limit boundary value ET2 is a boundary value that needs to be returned from the state of the light quantity Q1 (the state in which the light quantity is increased) to the normal light quantity Q2, and is set to 4.0 msec (1/250 sec) here. Yes. A large value for the charge accumulation time is defined as the upper limit side, and a small value is defined as the lower limit side (see FIG. 6).

  If it is determined in step S202 that the charge accumulation time et is smaller than the lower limit boundary value ET2, the process proceeds to step S203, and 1 is incremented to the second count variable c2. The second count variable c2 is a variable for counting the time when the charge accumulation time et exceeds (below) the lower limit boundary value ET2. In step S204, it is determined whether or not the second count variable c2 is larger than the second count constant CN2. The value of the second count constant CN2 is set to 60. Here, it is determined whether or not the time that exceeds (below) the lower limit boundary value ET2 is 1 second or more. On the other hand, if it is determined in step S202 that the charge accumulation time et is not shorter than the lower limit boundary value ET2, the process proceeds to step S206, and the second count variable c2 is set to zero.

  If it is determined in step S204 that the second count variable c2 is greater than the second count constant CN2, the process proceeds to step S205. In step S205, the second count variable c2 is set to 0, and the value of the light quantity variable q is set to 2. Further, the value of the stepwise light quantity variable qt is set to 11. The stepwise light quantity variable qt is a value indicating the position of the diaphragm 16 and the illumination light quantity when shifting between the light quantities Q1 and Q2 and between the light quantities Q2 and Q3 (see FIG. 6). When step S205 is executed, the process proceeds to step 225. On the other hand, if it is determined in step S204 that the second count variable c2 is not greater than the second count constant CN2, the process proceeds to step S225 as it is.

  If it is determined in step S201 that the value of the light quantity variable q is not 1, that is, the illumination light quantity is not increased (light quantity Q1), the process proceeds to step S207. In step S207, it is determined whether or not the value of the light quantity variable q is 2, that is, whether or not it is a normal illumination light quantity.

  When it is determined in step S207 that the value of the light quantity variable q is 2, the process proceeds to step S208. In step S208, it is determined whether the charge accumulation time et is longer than the upper limit set value ET1. That is, it is determined whether there is a need to increase the amount of illumination light. The upper limit set value ET1 is a boundary value on the upper limit side of the range where there is no need to increase the light amount in the state of the light amount Q2, and is set to 8.0 msec (1/125 sec) here.

  If it is determined in step S208 that the charge accumulation time et is longer than the upper limit set value ET1, the process proceeds to step S209, and 1 is incremented to the first count variable c1. The first count variable c1 is a variable for counting the time during which the charge accumulation time et exceeds the upper limit set value ET1. In step S210, it is determined whether or not the first count variable c1 is larger than the first count constant CN1. The value of the first count constant CN1 is set to 60. Here, it is determined whether or not the time exceeding the upper limit set value ET1 is 1 second or more.

  If it is determined in step S210 that the first count variable c1 is not greater than the first count constant CN1, the process proceeds to step S225. On the other hand, if it is determined in step S210 that the first count variable c1 is greater than the first count constant CN1, the process proceeds to step S211. In step S211, the first count variable c1 is set to 0, and the value of the light quantity variable q is set to 1. Also, the value of the stepwise light quantity variable qt is set to 1.

On the other hand, if it is determined in step S208 that the charge accumulation time et is not longer than the upper limit set value ET1, the process proceeds to step S212, and the first count variable c1 is set to zero. In step S213, it is determined whether the charge accumulation time et is smaller than the lower limit set value ET4. The lower limit set value ET4 is a lower limit side boundary value in a range where there is no need to reduce the light amount in the state of the light amount Q2, and is set to 0.25 msec ( 1/4000 sec) here.

  If it is determined in step S213 that the charge accumulation time et is smaller than the lower limit set value ET4, the process proceeds to step S214, and 1 is incremented to the fourth count variable c4. The fourth count variable c4 is a variable for counting the time when the charge accumulation time et exceeds (below) the lower limit set value ET4. In step S215, it is determined whether the fourth count variable c4 is greater than the fourth count constant CN4. The value of the fourth count constant CN4 is set to 60, and it is determined here whether or not the time that exceeds (below) the lower limit set value ET4 is 1 second or more. On the other hand, if it is determined in step S213 that the charge accumulation time et is not smaller than the lower limit set value ET4, that is, an appropriate illumination light quantity is supplied in the state of the light quantity Q2, the process proceeds to step S217, and the fourth count variable c4 is set to 0, and the routine goes to Step S225.

  If it is determined in step S215 that the fourth count variable c4 is not greater than the fourth count constant CN4, the process proceeds to step S225. On the other hand, if it is determined in step S215 that the fourth count variable c4 is greater than the fourth count constant CN4, the process proceeds to step S216. In step S216, the fourth count variable c4 is set to 0, and the value of the light quantity variable q is set to 3. Also, the value of the stepwise light quantity variable qt is set to 21. When step S216 is executed, the process proceeds to step S225.

  On the other hand, if it is determined in step S207 that the value of the light quantity variable q2 is not 2, the process proceeds to step S218. In step S218, it is determined whether or not the value of the light quantity variable q is 3, that is, the illumination light quantity is reduced (light quantity Q3).

If it is determined in step S218 that the value of the light amount variable light amount variable q is 3, the process proceeds to step S219, and it is determined whether or not the charge accumulation time et is greater than the upper limit boundary value ET3. The upper limit boundary value ET3 is a boundary value in the light amount range that does not need to be returned from the state of the light amount Q3 (the state in which the light amount is decreased) to the normal light amount Q2, and here, 0.5 msec ( 1/2000 sec).

  If it is determined in step S219 that the charge accumulation time et is longer than the upper limit boundary value ET3, the process proceeds to step S220, and 1 is incremented to the third count variable c3. The third count variable c3 is a variable for counting the time during which the charge accumulation time et exceeds (exceeds) the upper limit boundary value ET3. In step S221, it is determined whether the third count variable c3 is larger than the third count constant CN3. The value of the third count constant CN3 is set to 60. Here, it is determined whether or not the time that exceeds (exceeds) the upper limit boundary value ET3 is 1 second or more. On the other hand, when it is determined in step S219 that the charge accumulation time et is not longer than the upper limit boundary value ET3, that is, the illumination light quantity is appropriate in the state of the light quantity Q3, the process proceeds to step S223, and the third count variable c3 is set to 0. Then, the process proceeds to step S225.

  If it is determined in step S221 that the third count variable c3 is not greater than the third count constant CN3, the process proceeds to step S225. On the other hand, if it is determined in step S221 that the third count variable c3 is greater than the third count constant CN3, the process proceeds to step S222. In step S222, the third count variable c3 is set to 0, and the value of the light quantity variable q is set to 2. Further, the value of the stepwise light quantity variable qt is set to 31. When step S222 is executed, the process proceeds to step S225.

  On the other hand, if it is determined in step S218 that the value of the light quantity variable q is not 3, the process proceeds to step S224. This indicates that the value of the light quantity variable q is out of the definition range and is strange. Step S224 is processing in the case of emergency. In step S224, the value of the light quantity variable q is set to 2, and the value of the stepwise light quantity variable qt is set to 17. When step S224 is executed, the process proceeds to step S225.

  In step S225 of FIG. 4, it is determined whether or not the value of the stepwise light quantity variable qt is a value other than zero. When it is determined that the value of the stepwise light quantity variable qt is 0, the interrupt routine ends. On the other hand, if it is determined that the value of the stepwise light quantity variable qt is a value other than 0, the process proceeds to step S226, and 1 is incremented to the value of the stepwise light quantity variable qt.

  In step S227, it is determined whether or not the value of the stepwise light quantity variable qt is an even number. When switching from the light quantity Q2 to the light quantity Q1, from the light quantity Q1 to the light quantity Q2, or from the light quantity Q2 to the light quantity Q3, and from the light quantity Q3 to the light quantity Q2, the light quantity is changed stepwise at intervals of two fields (= 1/30 sec). A drive signal is output to the diaphragm 16 only when the value of the variable qt is an even number.

  If it is determined in step S227 that the value of the stepwise light quantity variable qt is an odd number, the interrupt routine ends as it is. On the other hand, when it is determined in step S227 that the value of the stepwise light quantity variable qt is an even number, the process proceeds to step S228, the position of the diaphragm 16 is set, and a control signal is output.

  As shown in FIG. 5, each value of the stepwise variable qt is associated with the position of the diaphragm 16. A light quantity Q12 to a light quantity Q28 are set corresponding to each value of the stepwise variable qt. When the aperture position is I12, the light quantity Q1 (= Q12), when the aperture position is I20, the light quantity Q2 (= Q20), and the aperture position is At I28, the light quantity is set to Q3 (= Q28). For example, when switching from the normal light quantity Q2 to the light quantity Q1, the initial value of the stepwise light quantity variable qt is set to 1 in step S211, and the value of the stepwise light quantity variable qt is 2, 4, 6, 8. Sometimes, the control signal is output so that the position of the diaphragm 16 changes in steps of I18, I16, I14, and I12. When step S228 is executed, the process proceeds to step S229.

  In step S229, it is determined whether or not the value of the stepwise light quantity variable qt is 8, 18, 28, or 38. That is, it is determined whether or not the diaphragm 16 has reached the final position in order to switch the illumination light quantity (see FIG. 5). If it is determined that the value of the stepwise light quantity variable qt is not 8, 18, 28, or 38, the interrupt routine ends. On the other hand, if it is determined that the value of the stepwise light quantity variable qt is 8, 18, 28, or 38, the process proceeds to step S230, and the value of the stepwise light quantity variable qt is set to 0. When step S230 is executed, the interrupt routine ends.

  As described above, according to the present embodiment, the charge accumulation time et exceeds the upper limit set value ET1 (exceeds) in the state where the brightness adjustment process is performed by the electronic shutter function in the state of the light quantity Q2. If the state continues for 1 second or longer (Yes at Steps S208 and S210), the position of the diaphragm 16 moves stepwise (Steps S211, S228), and the illumination light quantity shifts from the light quantity Q2 to the light quantity Q1. If the charge accumulation time et is shorter than the lower limit set value ET4 for 1 second or longer (steps S213 Yes, S215 Yes), the position of the diaphragm 16 moves stepwise (steps S216, S228), and the illumination light quantity is light quantity. Transition from Q2 to light quantity Q3. Thereby, the amount of light increases when the illumination is insufficient, and the amount of light decreases when the illumination is excessive.

  On the other hand, when the state where the charge accumulation time et is smaller than the lower limit boundary value ET2 continues for 1 second or more in the state where the light amount is increased (light amount Q1) (Yes at Steps S202 and S204), the position of the diaphragm 16 moves stepwise (Step S202). S205, S228), the illumination light quantity returns from the light quantity Q1 to the light quantity Q2. Further, when the charge accumulation time et is longer than the upper limit boundary value ET3 for 1 second or longer in the light amount decreased state (light amount Q3) (Yes in Steps S219 and S221), the position of the diaphragm 16 moves stepwise (Step S219). S222, S228), the illumination light quantity returns from the light quantity Q3 to the light quantity Q2.

  When the illumination light quantity is insufficient, the electronic shutter speed can be kept short in order to increase the illumination light quantity. Therefore, even when the subject is away from the distal end of the scope in still image shooting, no blurring occurs and observation is not hindered. In addition, since the illumination light amount is not always used at the maximum, and the maximum light amount is set only when necessary, it is possible to suppress the burn at the observation site and the heat generation at the distal end of the scope, which is a trivial problem.

  Here, the light quantity Q1 after the increase is set to 1.5 times the light quantity Q2 before the increase with respect to the illumination light quantity, but it may be set at a ratio other than that. The diaphragm 16 is selectively disposed in the optical path to increase the amount of light, but the amount of light may be adjusted by other configurations. The same applies to the light quantity Q2 and the light quantity Q3.

  Regarding the light amount control, an LED is provided at the distal end of the scope, and the light emission amount of the LED may be controlled. In this case, the light amount control is executed within the scope, and the light emission amount of the LED may be set and adjusted. In this case, since the light emission quantity is not always set to the maximum value but is set to the maximum value only when necessary, the lifetime of the LED can be extended. Also, with this configuration, all processing relating to brightness adjustment processing and light amount control can be performed by the video scope alone. Further, the brightness adjustment process may be executed inside the processor 10 instead of the scope control unit 56.

  Although the signal processing unit and the light source unit are integrally configured in the processor 10, the diaphragm may be provided in a light source device that is configured separately.

  Regarding the switching of the illumination light quantity, it may be set to a number of stages (for example, four stages) larger than the light quantities Q1, Q2, and Q3.

It is a block diagram of the electronic endoscope apparatus which is this embodiment. It is the flowchart which showed the whole control process of the processor. It is the flowchart which showed the light quantity control process in a processor. It is the flowchart which showed the light quantity control process in a processor. It is the figure which showed the value of the position of a stop, and a light quantity variable. It is the figure which showed the correspondence of the upper limit of a charge storage time, a lower limit, a boundary value, and illumination light quantity.

Explanation of symbols

10 processor 12 light source lamp 16 diaphragm 22 system control circuit 50 video scope 54 CCD
56 Scope Control Unit ET1 Upper limit set value ET2 Lower limit boundary value ET3 Upper limit boundary value ET4 Lower limit set value

Claims (9)

An electronic endoscope apparatus including a video scope having an image sensor,
A light source that illuminates the subject;
A luminance calculating means for calculating a luminance value based on an image signal corresponding to a subject image read from the image sensor;
Brightness adjusting means for adjusting the brightness of the subject image at predetermined time intervals by adjusting the charge accumulation time in the image sensor according to the calculated luminance value;
When the charge accumulation time exceeds the upper limit set value based on the illumination state where the light amount needs to be increased over the first allowable time, the illumination light amount is increased while the illumination state where the light amount needs to be decreased And a light amount control means for reducing the amount of illumination light when the charge accumulation time exceeds the second allowable time or more.   The electronic endoscope apparatus according to claim 1, wherein when the light quantity control unit increases or decreases the illumination light quantity, the illumination light quantity is changed stepwise.   2. The light amount control unit, after increasing the illumination light amount, when the charge accumulation time exceeds a lower limit boundary value for a third allowable time or longer, returns the illumination light amount before the increase. The electronic endoscope apparatus described in 1.   2. The light amount control unit returns the illumination light amount to a value before the decrease when the charge accumulation time exceeds an upper limit boundary value for a fourth allowable time or more after the illumination light amount is decreased. The electronic endoscope apparatus described in 1.   The electronic endoscope apparatus according to claim 1, wherein the light amount control unit is disposed inside the processor. The light quantity control means is
A diaphragm arranged in the optical path of the illumination light;
The electronic endoscope apparatus according to claim 1, further comprising: diaphragm driving means for driving the diaphragm. Luminance calculation means for calculating a luminance value based on an image signal corresponding to a subject image read from an image pickup device of a videoscope by illuminating the subject;
Brightness adjustment means for adjusting the brightness of the subject image at predetermined time intervals by adjusting the charge accumulation time in the image sensor according to the calculated luminance value;
When the charge accumulation time exceeds the upper limit set value based on the illumination state where the light amount needs to be increased over the first allowable time, the illumination light amount is increased while the illumination state where the light amount needs to be decreased And a light amount control means for reducing the amount of illumination light when the charge accumulation time exceeds the second allowable time or more. . Luminance calculation means for calculating a luminance value based on an image signal corresponding to a subject image read from an image pickup device of a videoscope by illuminating the subject;
Brightness adjustment means for adjusting the brightness of the subject image at predetermined time intervals by adjusting the charge accumulation time in the image sensor according to the calculated luminance value;
When the charge accumulation time exceeds the upper limit set value based on the illumination state where the light quantity needs to be increased over the first allowable time (exceeds), the illumination light quantity is increased while the light quantity needs to be reduced. And a light amount control means for reducing the amount of illumination light when the charge accumulation time exceeds (below) the second allowable time or less than a lower limit set value based on a characteristic illumination state. And video scope. Luminance calculation means for calculating a luminance value based on an image signal corresponding to a subject image read from an image pickup device of a videoscope by illuminating the subject;
Brightness adjustment means for adjusting the brightness of the subject image at predetermined time intervals by adjusting the charge accumulation time in the image sensor according to the calculated luminance value;
When the charge accumulation time exceeds the upper limit set value based on the illumination state where the light amount needs to be increased over the first allowable time, the illumination light amount is increased while the illumination state where the light amount needs to be decreased And a light amount control means for reducing the amount of illumination light when the charge accumulation time exceeds the second allowable time or more.

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