JP2011212382A - Electronic endoscope system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To achieve a long service life of a lamp while improving the quality of a still image.SOLUTION: This electronic endoscope system includes: a rotary plate having an opening for allowing illumination light to pass through and a shading part for shading the illumination light, and repeatedly generating an opening period for advancing the illumination light to an electronic endoscope, and a shading period for shading the illumination light; a shading plate that can be switched to a transmitting state of allowing the illumination light to pass through, and to a shading state of shading the illumination light; an operating means for starting acquisition of the still image; and a system control part for raising the quantity of the illumination light to perform exposure of an imaging element when a changeover to the acquisition of the still image is made by the operation of the operating means, then lowering the quantity of the illumination light, switching the shading plate to the shading state while the quantity of the illumination light is lowered, to shade the illumination light in the opening period, and returning the quantity of the illumination light to the light quantity for the acquisition of a moving image to return the shading plate to the transmitting state when the acquisition of the still image is switched to the acquisition of the moving image.

Description

  The present invention relates to an electronic endoscope system, and more particularly to an electronic endoscope system including a light source device for emitting illumination light for normal observation and illumination light for special light observation.

  2. Description of the Related Art Conventionally, electronic endoscope systems that can observe and image a target site by inserting a long and narrow insertion portion into a body cavity of a patient have been widely used. An image pickup device (CCD image sensor, CMOS image sensor, etc.) is provided at the distal end of the insertion portion of the electronic endoscope, and an image signal output by photoelectric conversion by the image pickup device is inserted through the electronic endoscope. The data is transmitted to a video processor connected to the electronic endoscope through a transmission cable such as a coaxial cable.

  The electronic endoscope system is provided with a light source device that supplies illumination light for imaging to the electronic endoscope. The amount of illumination light emitted from the light source device is adjusted by the light control device. As one of the light control devices, there is a rotary shutter. Patent Document 1 discloses a light control device using a rotary shutter. The rotary shutter disclosed in Patent Document 1 has two rotating plates each having an opening formed in an arc shape along the circumferential direction, and rotates each rotating plate at a variable rotational speed. The illumination light from the light source device is adjusted to a desired light amount according to the area where the openings overlap each other when passing through the openings of the respective rotating plates, and is supplied to the electronic endoscope. In the light source device, in synchronization with the opening period in which the illumination light passes through the opening of the rotating plate and travels to the electronic endoscope, the lamp current is increased to increase the amount of illumination light. Is decreased to reduce the amount of light, and this is repeated to increase or decrease the amount of illumination light. When changing the light quantity of illumination light, the area which the opening part of each rotating plate overlaps is changed by shifting the rotation phase of each rotating plate relatively.

  In the electronic endoscope system, a moving image and a still image can be acquired. When generating a moving image, the image sensor sequentially reads out the image signals of the odd field and the even field in a state where pixels of adjacent lines are added to each other by a field transfer, for example, every time interval of 1/60 seconds. And output to the monitor. In the electronic endoscope system of Patent Document 1, a light-shielding chopper that shields illumination light supplied to the electronic endoscope is provided. When the surgeon presses an operation button for acquiring a still image provided on the operation unit of the electronic endoscope, a light-shielding chopper is activated to expose the target part, and then the illumination light is shielded, and still image signal processing is performed. Is started. When generating a still image, the pixel signal for the still image is generated by transferring the image signal of all lines including the odd lines and the even lines by using the period in which the light is blocked by the light blocking chopper by frame transfer. can get.

JP 2008-104614 A

  However, in the conventional electronic endoscope system as described above, the light amount at the time of still image acquisition remains the same as that at the time of moving image acquisition. An image may be displayed on the monitor, which may interfere with diagnosis. In addition, when image processing for adjusting brightness, γ value, contrast, and the like is performed in the process of generating a still image, noise included in the image signal may increase and image quality may be degraded.

  The present invention has been made in view of the above circumstances. An object of the present invention is to provide an electronic endoscope system including a light source device capable of improving the quality of a still image while acquiring a good moving image. It is another object of the present invention to suppress current consumption while solving a shortage of light quantity when acquiring a still image.

  The electronic endoscope system of the present invention is generated by an electronic endoscope having an image sensor for acquiring a moving image or a still image of a target part, a light source for supplying illumination light for imaging the target part, and the image sensor A video processor having a processing circuit that converts an image signal of a moving image or a still image of a target region into a video signal, and an electronic endoscope having a monitor that receives and displays the video signal from the video processor In the system, the electronic endoscope system further includes an opening that allows the illumination light to pass therethrough and a light shielding portion that blocks the illumination light, and rotates the illumination light through the opening by rotating at a predetermined rotation speed. A rotating plate that repeatedly generates an opening period for proceeding to the electronic endoscope and a light shielding period for shielding the illumination light by the light shielding unit, a transmission state for passing the illumination light, and shielding the illumination light. A light shielding plate that can be switched between a light shielding state, an operation unit for starting acquisition of a still image, and a light amount of illumination light when switching from acquisition of a moving image to acquisition of a still image by a still image acquisition operation by the operation unit After the image sensor has been exposed to light, the illumination light amount is reduced, and while the illumination light amount is reduced, the light shielding plate is switched from the transmissive state to the light shielding state to block the illumination light during the opening period. When switching from acquisition of a still image to acquisition of a moving image, the rotating plate, the light source, and the light shielding plate are controlled so that the light amount of the illumination light is returned to the light amount at the time of moving image acquisition and the light shielding plate is returned to the transmission state. And a system control unit.

  Preferably, when a still image acquisition operation is performed by the operation unit, the system control unit increases the amount of illumination light in synchronization with the opening period, and after the opening period when the amount of illumination light is increased, a predetermined light source Only during the cooling period, the amount of illumination light is made lower than the amount of illumination light at the time of moving image acquisition, the light shielding plate is switched from the transmission state to the light shielding state during the predetermined light source cooling period, and after the predetermined light source cooling period has elapsed. The light amount of the illumination light emitted from the light source is returned to the light amount at the time of moving image acquisition, and after maintaining the light shielding state of the light shielding plate in the opening period overlapping the predetermined light source cooling period, the light shielding plate is returned to the transmissive state. The rotating plate, the light source and the light shielding plate are controlled.

  More preferably, the predetermined light source cooling period is obtained by the following equation (1).

Here, T _cool is a predetermined light source cooling period, I _max is the current value of the current supplied to the light source when the amount of illumination light is increased in synchronization with the opening period, and I _min is the amount of illumination light stationary. the current value of the current supplied to the light source unit when the lower than the amount of illumination light before the start of the acquisition of the image, I _r is the rated value of the current supplied to the light source unit, T _bst is the opening period This is a current amplification period of the current supplied to the light source unit when the amount of the illumination light is increased synchronously. Further, the operation means is included in the operation unit of the electronic endoscope or the front panel of the video processor.

  According to the electronic endoscope system of the present invention, since the current to the light source is increased only at the time of still image acquisition, it is not necessary to repeatedly increase and decrease the current to the light source as in the conventional electronic endoscope system. Further, since the opening period of the rotating plate and the increase in the current to the light source are synchronized, the amount of illumination light can be increased for a required time. Furthermore, the light source cooling period is ensured after increasing the current to the light source. Therefore, the lifetime of the light source can be increased. In addition, since the amount of light is not increased when moving images are acquired, the quality of still images can be improved without causing halation in the moving images.

FIG. 1 is a schematic diagram showing an electronic endoscope system according to an embodiment of the present invention. FIG. 2 is a schematic diagram illustrating a rotating plate of the electronic endoscope system according to the embodiment of the present invention. FIG. 3 is a timing chart of processing of each unit of the electronic endoscope system according to the embodiment of the present invention.

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

  FIG. 1 shows a schematic diagram of an electronic endoscope system 100 in the present embodiment. The electronic endoscope system 100 includes an electronic endoscope 1, a video processor 2, a monitor 3, and a keyboard 4. The lamp 33 of the video processor 2 includes a high-intensity lamp such as a xenon lamp, a halogen lamp, a mercury lamp, or a metal halide lamp as a light source, and generates illumination light such as white light for imaging by the electronic endoscope 1. Power for the lamp 33 is supplied from the lamp control unit 34. The illumination light emitted from the lamp 33 is incident on the first rotating plate 12 and the second rotating plate 17 via a light shielding plate 35 connected to a condensing optical system 32 and a solenoid as an actuator. The light shielding plate 35 functions as a shutter that shields illumination light by electromagnetically driving a solenoid based on the control of the system control unit 26.

  The first rotating plate 12 rotates around the rotation axis by the driving force of the motor 13. The motor 13 is provided with a rotary encoder 14. The rotary encoder 14 detects control information such as the rotation frequency of the motor 13 and sends it to the motor control circuit 16. The motor control circuit 16 sends a control signal to the driver 15 based on the timing control signal from the timing control unit 27 and the control information from the rotary encoder 14. The driver 15 drives the motor 13 based on a control signal from the motor control circuit 16. The feedback control of the motor 13 in this way causes the first rotary plate 12 to rotate at a desired rotational speed.

  FIG. 2 shows a schematic diagram of the first rotating plate 12. The first rotating plate 12 is provided with an arc-shaped opening 12 a centering on the rotation axis C along the circumferential direction of the first rotating plate 12. Further, in the first rotating plate 12, a light shielding portion 12b is formed except for the opening portion 12a. Therefore, the illumination light from the lamp 33 (indicated by L in FIG. 2) alternately enters the opening 12a and the light shielding portion 12b in accordance with the rotation of the first rotating plate 12. The illumination light passes through the opening 12a when entering the opening 12a and proceeds to the second rotating plate 17, and is blocked when entering the light shielding part 12b.

  The second rotating plate 17 is rotated by the motor 18 in the same manner as the first rotating plate 12. The motor 13 is provided with a rotary encoder 19, and the rotary encoder 19 is connected to a motor control circuit 21. The motor control circuit 21 is connected to the timing control unit 27 and the driver 20. The driver 20 is connected to the motor 18. Since the processing of each part that controls the rotation of the second rotating plate 17 is the same as that of the first rotating plate 12, illustration and description thereof are omitted. The second rotating plate 17 is also provided with an arc-shaped opening centered on the rotation axis along the circumferential direction of the rotating plate. Further, in the second rotating plate 17, a light shielding part is formed except for the opening part. The opening of the first rotating plate 12 and the opening of the second rotating plate 17 have the same size and shape and are provided at positions separated from the rotation axis by the same distance. Accordingly, the illumination light that has passed through the opening of the first rotating plate 12 is incident on the opening or the light shielding portion in accordance with the rotation of the second rotating plate 17. When the illumination light enters the opening, the illumination light passes through the opening and travels to the diaphragm 22, and when it enters the light shielding portion, the illumination light is shielded.

  The first rotating plate 12 and the second rotating plate 17 have their rotation axes on the same straight line, and rotate in the same direction independently of each other. Further, since the rotational speeds of the first rotating plate 12 and the second rotating plate 17 can be controlled independently, the first rotating plate 12 and the second rotating plate 17 can be moved at a desired rotational phase difference. Can be rotated. Due to the rotational phase difference between the first rotary plate 12 and the second rotary plate 17, the openings of each other rotate with a rotational angle corresponding to the rotational phase difference. By increasing or decreasing the rotational phase difference, the area where the openings overlap each other in the direction of the rotation axis is reduced or increased. Therefore, by changing the rotational phase difference, the amount of illumination light reaching the diaphragm 22 can be reduced or increased. The diaphragm 22 can finely adjust the amount of illumination light transmitted through the first rotary plate 12 and the second rotary plate 17. The opening degree of the diaphragm 22 is controlled by a motor 23. In the light control by the diaphragm 22, for example, the brightness of the observation target part as the subject is determined by the light control circuit 25 from the luminance signal Y generated by the signal processing circuit 8 based on the image signal from the CCD as the image sensor. An average luminance value indicating the average value is calculated. Then, the calculated average luminance value is compared with a reference luminance value indicating the brightness that is the reference of the subject image. Then, based on the difference between the average luminance value and the reference luminance value as the comparison result, the amount of narrowing until the diaphragm 22 reaches the target narrowing position is calculated. A control signal for driving the motor 23 is sent to the driver 24 in accordance with the calculated aperture amount of the aperture 22, and the motor 23 is driven by the control of the driver 24 to change the opening degree of the aperture 22. The amount of light is adjusted.

  The illumination light whose light amount is adjusted by the diaphragm 22 travels to the incident end face of the light guide 11 and propagates to the tip of the electronic endoscope 1. The light guide 11 is inserted through the operation portion 1b and the body cavity insertion portion 1a of the electronic endoscope 1 from the base portion 1c which is a connection portion between the electronic endoscope 1 and the video processor 2, and the distal end of the body cavity insertion portion 1a. It extends to. The operation unit 1b grasped by the surgeon is provided with a plurality of operation buttons 1d for performing various operations by the surgeon, an angle knob (not shown), a treatment instrument insertion port (not shown), and the like. . The treatment instrument insertion port communicates with a treatment instrument opening (not shown) provided at the distal end of the electronic endoscope 1. The operator inserts a treatment tool such as forceps from the treatment tool insertion port, causes the treatment tool to appear and disappear from the treatment tool opening through a treatment tool insertion channel (not shown) provided in the electronic endoscope 1, and the body cavity. Take measures such as collecting tissue inside. The angle knob bends the distal end portion of the body cavity insertion portion 1a of the electronic endoscope 1 according to the turning operation. In addition, by operating each button, there are various types of operations such as air supply and water supply to the observation target part, suction of body fluid, etc., stillness of the screen on the monitor 3, recording of a still image and a moving image of the observation target part on the image recording medium, etc. Processing can be performed.

  At the tip of the electronic endoscope 1, a light distribution optical system 5 and a condensing optical system 6 are disposed. The light distribution optical system 5 is provided at a position facing the emission end face of the light guide 11 that propagates the illumination light from the lamp 33, and emits the illumination light propagated by the light guide 11 to a target site. The condensing optical system 6 condenses the reflected light from the target part on the light receiving surface of the CCD 7 and forms an image of the target part.

  In the CCD 7, the received light is photoelectrically converted to generate an image signal. The image signal is amplified by a preamplifier (not shown), and then a signal processing circuit 8 provided in the base 1 c of the electronic endoscope 1. Sent to. In the signal processing circuit 8, the image signal is converted into an image signal composed of the luminance signal Y and the color difference signals Cb and Cr, converted into a digital signal, and then sent to the image generation circuit 28 of the video processor 2. Further, in the base 1 c of the electronic endoscope 1, the control circuit 10 is connected to the signal processing circuit 8 and the EEPROM 9. When the electronic endoscope 1 is connected to the video processor 2, the control circuit 10 stores identification information of the electronic endoscope 1 and information related to the CCD 7 that are necessary for performing various controls on the video processor 2 side. The data is read from the EEPROM 9 and sent to the system control unit 26 of the video processor 2. Further, the control circuit 10 controls driving of the CCD 7 and processing of the signal processing circuit 8 based on a signal received from the system control unit 26 of the video processor 2.

  The image generation circuit 28 of the video processor 2 performs various image processing on the image signal sent from the signal processing circuit 8 of the electronic endoscope 1. The image generation circuit 28 amplifies the luminance signal Y and the color difference signals Cb and Cr sent from the signal processing circuit 8 and then performs color correction on the image signal. Further, the image generation circuit 28 converts the input luminance signal Y and color difference signals Cb, Cr into three primary color signals R, G, B having no color mixture, and outputs them. The converted R, G, B image signals are amplified and adjusted to an appropriate signal level, and then stored in an image memory (not shown) in the image generation circuit 28 for each color. A signal for one frame is read from the image memory, and a horizontal synchronization signal and a vertical synchronization signal output from the timing control unit 27 are added to the video process unit 29. In the video process unit 29, the image signal is converted into a digital video signal, an RGB video signal, a composite video signal, an S video signal or the like, and then output to the monitor 3 as a video signal of an observation image. The surgeon observes and treats a site in the body cavity while confirming the observation image displayed on the monitor 3.

  Here, the operation of each part of the electronic endoscope system in the present embodiment will be described with reference to the timing chart of FIG. For convenience, the opening of the rotating plate and the timing of light shielding are shown assuming that the first rotating plate 12 and the second rotating plate 17 are one rotating plate. For convenience, the level of the lamp current supplied to the lamp 33 is divided into three stages of high, medium, and low, and the lamp current is supplied at a medium level when a moving image is captured. In this embodiment, the rotating plate rotates once in 1/30 seconds, the illumination light from the lamp 33 is transmitted through the opening for 1/90 seconds, and the subsequent 1/45 seconds are shielded by the light shielding portion. The illumination light is supplied to the electronic endoscope 1 by repeating the transmission and shielding of the illumination light every 1/30 seconds. The CCD 7 accumulates charges and transfers accumulated charges in synchronization with the opening of the rotating plate and the timing of light shielding. When a moving image is acquired, exposure is performed during the opening period of the rotating plate to accumulate charges, and the accumulated charge is transferred during the light shielding period of the rotating plate.

  In the present embodiment, the CCD 7 performs interlace scanning. When a moving image is displayed on the monitor 3, field readout, that is, field transfer is performed, and adjacent pixels are added to each other at a time interval of 1/60 seconds based on the drive signal sent from the control circuit 10. In this state, the image signals in the odd field and the even field are sequentially read out and transferred to the signal processing circuit 8. That is, the image signal of the CCD 7 is read out by a so-called color difference line sequential method.

  On the other hand, when the surgeon performs a still image acquisition operation and displays the still image on the monitor 3, frame reading, that is, frame transfer, in which an image signal for one frame is read by the same exposure is performed. That is, an image signal for one frame accumulated in the CCD 7 by one exposure is divided into an odd-numbered line image signal and an even-numbered line image signal in the pixel array of the CCD 7, and each image signal for one field is in turn. Is read out. Accordingly, the odd line and even line image signals for one field are sent to the signal processing circuit 8 respectively, and after the image processing circuit 28 performs image processing as the odd field image signal and the even field image signal, It is output to the monitor 3.

Here, an operation in the electronic endoscope system 100 when acquiring a still image will be described. When acquiring a still image, the operator operates the operation button 1d of the operation unit 1b of the electronic endoscope 1, the buttons provided on the front panel 30 of the video processor 2, the keyboard 4, and the like to acquire the still image. Start. When the surgeon operates the operation button 1d of the operation unit 1b, the button of the front panel 30, or the like, a still image acquisition pulse Tr is sent to the system control unit 26 as a trigger for a still image generation process. System control unit 26 acquires the still image acquisition pulse Tr, sends a control signal to the lamp controller 34, increasing the lamp current level supplied to lamp 33 in accordance with the start of the opening period P ₁ of the rotary plate at a high Thus, the light quantity of the lamp 33 is increased. Further, the system control unit 26, the opening period P ₁ of the rotating plate at the same time to start the closing operation of the light shielding plate 35 when end to increase the amount of light of the lamp 33. In the present embodiment, it is assumed that the opening operation and the closing operation of the light shielding plate 35 each take 1/45 seconds from the operation start to the operation completion. The light shielding plate 35 starts closing operation under the control of the system control unit 26. Timing the opening period P ₂ starts rotating plate closing operation of the light shielding plate 35 is a completed timing coincide. Further, the light shielding plate 35 is maintained in the closed state only for the opening period of the rotating plate of 1/90 seconds after the closing operation is completed under the control of the system control unit 26. The light shielding plate 35 starts to open after being kept closed for 1/90 seconds. Since it takes is from the start to the end of the opening operation 1/45 seconds, the start time of the opening period P ₃ of the completion time of the opening operation of the light shielding plate 35 and the next rotation plate coincide.

Furthermore, the system control unit 26 lowers the lamp current level supplied to lamp 33 in accordance with the end of the opening period P ₁ of the rotary plate lower. As a result, the temperature of the lamp 33 temporarily raised by raising the lamp current level to high and increasing the irradiation light amount is lowered. Here, the lamp cooling period as a period for lowering the lamp current level is obtained by the following equation (2).

Here, T _cool the lamp cooling period, I _max is the current value of the lamp current when the lamp current level is high, I _min is the current value of the lamp current when the lamp current level is low, I _r is the ramp The rated current value, T _bst, is the current amplification period of the lamp current when the lamp current level is increased. The average current consumption of the lamp current in the total duration of the cooling period T _cool and current amplification period T _bst does not exceed the rated value I _r of the lamp current.

The case shown in FIG. 3, the lamp cooling period is less than 1/18 seconds, i.e., 2 lamp current level after the opening period P ₁ of the rotating plate high in to have increased the amount of illumination light is finished One opening period P ₃ of the rotating plate after is less than the time to start. When the lamp cooling period ends, the lamp control unit 34 returns the lamp current level to the middle level for moving image capturing based on the control of the system control unit 26.

The light shielding plate 35, the illuminating light is blocked since the opening period P ₂ in the light shielding plate 35 of the rotating plate which follows after raising the lamp current level to a high is closed. CCD7, the opening period P ₁ of the rotary plate raised lamp current level to a high starts transferring charges accumulated in the still image is terminated. As shown in FIG. 3, the transfer of charge accumulated in the moving picture is executed by the field transfer, from an opening period P ₁ of the rotating plate is finished to the opening period P ₃ is completed, switch from the field transferred to the frame transfer The stored charge of the still image is transferred. As described above, after the lamp is cooled while increasing the light amount of the illumination light only at the time of acquiring the still image and securing the transfer period of the stored image charge from the CCD 7 by the opening / closing operation of the light shielding plate 35, the illumination light is supplied. Can be returned to the level for capturing moving images. Further, even after the still image is displayed on the monitor 3, the light quantity of the lamp can be returned to the state before the process of acquiring the still image, and the moving image capturing process can be continued smoothly.

The above is the description regarding the embodiment of the present invention. The present invention is not limited to the above-described configuration, and various modifications can be made within the scope of the technical idea of the present invention. In the above description, since the lamp cooling period is less than 1/18 sec, although the opening period of the rotary plate that is blocked by the light blocking plate 35 is only the period P _2, the lamp cooling period is equal to or greater than 1/18 seconds In this case, the light shielding plate 35 can shield light over the opening periods of the plurality of rotating plates. For example, during each of the opening periods P ₂ and P ₃ , the processing of each unit can be performed so that the illumination light is shielded by the light shielding plate 35 and the moving image capturing is restarted from the opening period P ₄ . In the above description, the image signal for moving images is transferred by field transfer and the image signal for still images is transferred by frame transfer. However, the lamp cooling period is secured and the process returns to image processing of moving images. If possible, any transfer method can be employed. Further, the time required for the closing operation and the opening operation of the light shielding plate 35 is not limited to 1/45 seconds in the case of the above embodiment as long as the closed state can be maintained in the opening period of the rotating plate during the lamp cooling period. The operation may be enabled in a short time. Further, the light shielding plate 35 is not limited to the position between the lamp 33 and the first rotating plate 12 and can be disposed at an arbitrary position on the optical path of the illumination light.

1 Electronic Endoscope 1b Operation Unit 1d Operation Button 7 CCD
12, 17 Rotating plate 12a Opening portion 12b Light shielding portion 33 Lamp 34 Lamp control portion 35 Light shielding plate

Claims (5)

An electronic endoscope having an image sensor for acquiring a moving image or a still image of a target part, a light source that supplies illumination light for imaging the target part, and a moving image of the target part generated by the image sensor or In an electronic endoscope system comprising: a video processor having a processing circuit that performs signal processing of an image signal of a still image to convert it into a video signal; and a monitor that receives and displays the video signal from the video processor.
The electronic endoscope system further includes:
It has an opening that allows the illumination light to pass therethrough and a light-shielding portion that blocks the illumination light, and rotates at a predetermined rotation speed so that the illumination light passes through the opening and proceeds to the electronic endoscope. A rotating plate that repeatedly generates an opening period and a light shielding period in which the illumination light is shielded by the light shielding unit;
A light shielding plate capable of switching between a transmissive state that allows the illumination light to pass therethrough and a light shielding state that shields the illumination light;
Operation means for starting acquisition of a still image;
When switching from acquisition of a moving image to acquisition of a still image by a still image acquisition operation by the operation means, after increasing the amount of illumination light and exposing the image sensor, the amount of illumination light is decreased and the illumination While the amount of light is being reduced, the light shielding plate is switched from the transmission state to the light shielding state, the illumination light is shielded during the opening period, and the illumination is switched from acquisition of a still image to acquisition of a moving image. A system control unit that controls the rotating plate, the light source, and the light shielding plate so as to return the light amount to the light amount at the time of moving image acquisition and to return the light shielding plate to a transmission state;
An electronic endoscope system characterized by that. The system control unit is
When a still image acquisition operation is executed by the operation means,
Increasing the amount of illumination light in synchronization with the opening period,
After the elapse of the opening period in which the light amount of the illumination light is increased, the light amount of the illumination light is lower than the light amount of the illumination light at the time of moving image acquisition only during a predetermined light source cooling period,
During the predetermined light source cooling period, the light shielding plate is switched from a transmission state to a light shielding state,
After the elapse of the predetermined light source cooling period, the light amount of the illumination light emitted from the light source is returned to the light amount at the time of moving image acquisition,
Controlling the rotating plate, the light source, and the light shielding plate so as to return the light shielding plate to a transmissive state after maintaining the light shielding state of the light shielding plate in an opening period overlapping the predetermined light source cooling period;
The electronic endoscope system according to claim 1. The predetermined light source cooling period is obtained by the following equation (1).

Here, T _cool is the predetermined light source cooling period, I _max is the current value of the current supplied to the light source when the amount of illumination light is increased in synchronization with the opening period, and I _min is the illumination light. the current value of the current supplied to the light source when the lower than the amount of light amount of illumination light before the start of the acquisition of a still image, the rated value of the current I _r to be supplied to the light source, T _bst is opening It is a current amplification period of the current supplied to the light source when the amount of the illumination light is increased in synchronization with the period.
The electronic endoscope system according to claim 2.   The electronic endoscope system according to any one of claims 1 to 3, wherein the operation means is included in an operation unit of the electronic endoscope.   The electronic endoscope system according to any one of claims 1 to 4, wherein the operation unit is included in a front panel of the video processor.

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