JP2012143319A - Endoscope system and method for driving the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope system having a distal end equipped with an MOS type solid-state image pickup element, wherein a low-noise observation image is obtained by preventing an increase in temperature of the solid-state image pickup element.SOLUTION: The endoscope system includes: an electronic endoscope which has a distal end equipped with the MOS type solid-state image pickup element and an illumination portion adjacent to the MOS type solid-state image pickup element, causes the illumination portion to illuminate a subject in a body cavity when the distal end portion is inserted into the cavity, and captures an image of the subject by the MOS type solid-state image pickup element; a temperature detecting means which detects the temperature of the MOS type solid-state image pickup element; and a processor in which when the detected temperature by the temperature detecting means increases and reaches a threshold in the process where the MOS type solid-state image pickup element is driven at a drive mode for causing the MOS type solid-state image pickup element to output an image of the subject at a first frame (Fig.5(a)), the MOS type solid-state image pickup element is driven at a drive mode for changing the frame rate from the first frame rate to a second frame rate lower than the first one (Fig.5(b)).

Description

  The present invention relates to an endoscope system including an electronic endoscope having a MOS type solid-state imaging device mounted at the distal end portion of the endoscope, and a driving method thereof.

  In the medical field, medical diagnosis using an endoscope system is actively performed. The endoscope system includes an electronic endoscope (scope) having an insertion portion that is inserted into a body cavity, and a main body device to which the electronic endoscope is detachably connected.

  The main body device receives an imaging signal output from a solid-state imaging device built in the electronic endoscope, performs image processing, and outputs an observation image to a monitor, and is inserted into the electronic endoscope A light source device for generating light for illuminating the inside of the body cavity through the light guide.

  In recent years, as described in Patent Document 1, a solid-state imaging device mounted at the distal end of an insertion portion of an electronic endoscope is a CMOS (which can be driven at a low voltage and can easily be increased in number of pixels and at high speed. Complementary Metal Oxide Semiconductor) type is increasing.

  In general, in many CMOS solid-state imaging devices, a plurality of pixels are arranged in a matrix on a light receiving surface (imaging surface), and exposure control is performed by a rolling shutter which is a kind of electronic shutter.

  That is, as shown in FIG. 8, the light incident on the light receiving surface is accumulated in the photosensor of each pixel as a charge at a timing sequentially shifted in the time axis direction for each pixel row. The charges accumulated in the photosensors of the pixels by such sequential exposure control are read out as pixel signals at timings that are sequentially shifted in the time axis direction for each pixel row.

  In the example shown in FIG. 8, the field period (one vertical synchronization period) is 1/60 second, and the charge signals of all the pixel rows are sequentially read out by the progressive scanning method every field period. That is, an image signal (imaging signal) for one frame is output from the solid-state imaging device every 1/60 seconds.

  However, in the CMOS type solid-state imaging device in which the exposure control is performed by the rolling shutter, the exposure period is shifted for each pixel row as shown in FIG. There is a problem that the captured image is distorted.

  In addition, an illumination window for irradiating subject illumination light is provided on the distal end surface of the insertion portion of the electronic endoscope in the vicinity of the observation window opened in the light receiving surface of the solid-state imaging device. The illumination window is provided with a concave lens, a phosphor or the like that diffuses illumination light irradiated from the light source device side and incident through the light guide. When the illumination time becomes longer, these generate heat and raise the temperature of the solid-state imaging device.

  Compared to CCD solid-state image sensors, CMOS solid-state image sensors are less likely to generate heat due to their low drive voltage, but if there is a heating element nearby, the temperature rises and noise in the captured image increases. The problem arises.

  Therefore, although it is an example of a CCD type solid-state imaging device, the temperature of the solid-state imaging device is detected, the maximum exposure time is changed based on the detected temperature, or a mode corresponding to the detected temperature among a plurality of long-time exposure modes provided A technique for selecting is described in Patent Document 2.

  However, if the temperature of the solid-state imaging device rises during observation of the subject and the maximum exposure time or the like changes, the image quality of the subject image being observed changes abruptly. Further, when this problem occurs simultaneously with the above-described distortion of the captured image, the operator (observer: doctor) of the electronic endoscope feels uncomfortable.

JP 2009-201540 A JP 2005-323984 A

  An object of the present invention is to make it possible to suppress an increase in temperature even when the temperature of a solid-state image sensor rises, and that a captured image is distorted even when a subject moves relatively quickly with respect to the solid-state image sensor. It is an object of the present invention to provide an endoscope system and a driving method thereof.

  In the endoscope system and the driving method thereof according to the present invention, a MOS type solid-state imaging device is mounted at a distal end portion, and an illumination unit is provided adjacent to the MOS solid-state imaging device, and the distal end portion is placed in a body cavity of a subject. An electronic endoscope that illuminates a subject in the body cavity with the illuminating unit and captures an image of the subject with the MOS type solid-state image sensor when the camera is inserted, and temperature detection that detects the temperature of the MOS type solid-state image sensor And detecting the temperature while driving the MOS solid-state image sensor in a drive mode in which an image of the subject is output from the MOS solid-state image sensor at a first frame rate. Driving the MOS solid-state imaging device in a driving mode in which the frame rate is set to a second frame rate lower than the first when the temperature detected by the means rises and reaches a threshold value And features.

  Preferably, the light source is controlled to be turned on and off, and the light source is turned on only for a predetermined period in a period in which all pixel rows of the MOS type solid-state imaging device driven by a rolling shutter are in a light-receiving state. And

  According to the present invention, since the subject image is captured at a high frame rate (first frame rate), there is little image distortion, and when the temperature rises, the temperature also decreases to achieve a low frame rate (second frame rate). An object image with low noise can be obtained.

  Furthermore, since the light source is turned on only for a predetermined period during the period in which all the pixel rows of the MOS type solid-state imaging device driven by the rolling shutter are in the light receiving state, there is no time shift between the pixel rows and image distortion is avoided. The Since the illumination part at this time is intermittently irradiated with light from the light source, the light source off period becomes the cooling period of the illumination part, and the temperature rise is suppressed.

1 is an overall configuration diagram of an endoscope system according to an embodiment of the present invention. It is a front end surface front view of the front-end | tip part of the electronic endoscope shown in FIG. FIG. 2 is a cross-sectional view of a distal end portion of the electronic endoscope shown in FIG. It is a block block diagram of the control system of the endoscope system shown in FIG. It is 1st drive mode explanatory drawing of the endoscope system which concerns on embodiment of this invention. It is 2nd drive mode explanatory drawing of the endoscope system which concerns on embodiment of this invention. It is a 3rd drive mode explanatory view of the endoscope system concerning the embodiment of the present invention. It is explanatory drawing of the rolling shutter used with a CMOS type solid-state image sensor.

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

  FIG. 1 is an overall configuration diagram showing a schematic configuration of an endoscope system according to an embodiment of the present invention. The endoscope system 10 according to the present embodiment includes an electronic endoscope 12, a processor device 14 and a light source device 16 constituting a main body device. The electronic endoscope 12 includes a flexible insertion portion 20 that is inserted into a body cavity of a patient (subject), an operation portion 22 that is connected to a proximal end portion of the insertion portion 20, a processor device 14, and a light source. And a universal cord 24 connected to the device 16.

  A distal end portion 26 is connected to the distal end of the insertion portion 20, and an imaging chip (imaging device) 54 (see FIG. 3) for intra-body cavity imaging is built in the distal end portion 26. Behind the distal end portion 26 is provided a bending portion 28 in which a plurality of bending pieces are connected. When the angle knob 30 provided in the operation section 22 is operated, the bending section 28 is bent / moved in the vertical and horizontal directions by pushing / pulling the wire inserted in the insertion section 20. Thereby, the front-end | tip part 26 is orientated in the desired direction within a body cavity.

  A connector 36 is provided at the base end of the universal cord 24. The connector 36 is of a composite type and is connected to the light source device 16 in addition to being connected to the processor device 14.

  The processor device 14 supplies power to the electronic endoscope 12 via a cable 68 (see FIG. 3) inserted into the universal cord 24, controls the driving of the imaging chip 54, and connects the cable 68 from the imaging chip 54. The received image signal is received, and various signal processing is performed on the received image signal to convert it into image data.

  The image data converted by the processor device 14 is displayed as an endoscopic image on a monitor 38 connected to the processor device 14 by a cable. The processor device 14 is also electrically connected to the light source device 16 via the connector 36, and comprehensively controls the operation of the endoscope system 10 including the light source device 16.

  FIG. 2 is a front view showing the distal end surface 26 a of the distal end portion 26 of the electronic endoscope 12. As shown in FIG. 2, an observation window 40, an illumination window 42, a forceps outlet 44, and an air / water supply nozzle 46 are provided on the distal end surface 26 a of the distal end portion 26.

  The observation window 40 is arranged eccentrically at the center and one side of the distal end surface 26a. Two illumination windows 42 are arranged at symmetrical positions with respect to the observation window 40, and irradiate illumination light from the light source device 16 to a site to be observed in the body cavity. A concave lens may be used as the illumination window 42 to spread the illumination light over a wide range.

  The forceps outlet 44 is connected to a forceps channel 70 (see FIG. 3) disposed in the insertion portion 20 and communicates with a forceps port 34 (see FIG. 1) provided in the operation portion 22. Various treatment tools having an injection needle, a high-frequency knife or the like disposed at the distal end are inserted into the forceps port 34, and the distal ends of the various treatment instruments are ejected from the forceps outlet 44 into the body cavity.

  The air supply / water supply nozzle 46 is cleaned from the air supply / water supply device built in the light source device 16 in accordance with the operation of the air supply / water supply button 32 (see FIG. 1) provided in the operation unit 22. Water or air is jetted toward the observation window 40 or the body cavity.

  FIG. 3 is a longitudinal sectional view of the distal end portion 26 of the electronic endoscope 12. As shown in FIG. 3, a lens barrel 52 that holds an objective optical system 50 for taking in image light of a site to be observed in the body cavity is disposed behind the observation window 40. The lens barrel 52 is attached so that the optical axis of the objective optical system 50 is parallel to the central axis of the insertion portion 20. Connected to the rear end of the lens barrel 52 is a prism 56 that guides the image light of the site to be observed via the objective optical system 50 toward the imaging chip 54 by bending it at a substantially right angle.

  The imaging chip 54 is a monolithic semiconductor (so-called CMOS sensor chip) in which a CMOS solid-state imaging device 58 and a peripheral circuit 60 that drives the solid-state imaging device 58 and inputs / outputs signals are integrally formed. Implemented above.

  The imaging surface (light receiving surface) 58 a of the solid-state imaging device 58 is disposed so as to face the emission surface of the prism 56. On the imaging surface 58a, a rectangular plate-like cover glass 64 is attached via a rectangular frame-like spacer 63. The imaging chip 54, the spacer 63, and the cover glass 64 are assembled through an adhesive, and thereby the imaging surface 58a is protected from intrusion of dust and the like.

  A plurality of input / output terminals 62 a are arranged in the width direction of the support substrate 62 at the rear end portion of the support substrate 62 extending toward the rear end of the insertion portion 20. The input / output terminal 62a is joined to a signal line 66 for mediating the exchange of various signals with the processor device 14 via the universal cord 24. The input / output terminal 62a is a wiring formed on the support substrate 62. And a peripheral circuit 60 in the imaging chip 54 through a bonding pad or the like (not shown).

  The signal lines 66 are collectively inserted into a flexible tubular cable 68. The cable 68 is inserted through each of the insertion unit 20, the operation unit 22, and the universal cord 24 and is connected to the connector 36.

  Although not shown in FIGS. 2 and 3, an illumination unit is provided in the back of the illumination window 42. The illumination section is provided with an emission end 120a of a light guide 120 (see FIG. 4) for guiding illumination light from the light source device 16, and in this embodiment, a phosphor is provided between the emission end and the illumination window 42. 53 is provided. Similarly to the cable 68, the light guide 120 is inserted through each of the insertion unit 20, the operation unit 22, and the universal cord 24, and the incident end is connected to the connector 36.

  In this embodiment, a temperature sensor 55 that detects the temperature of the image sensor chip 54 is embedded in the chip 54 or in the support substrate 62, and the detection signal is transmitted to the processor device 14 through the signal line 66.

  FIG. 4 is a block diagram showing a control system of the endoscope system 10. As shown in FIG. 4, a solid-state image sensor 58, an analog signal processing circuit (AFE: analog front end) 72, a TG (timing generator) 78, and a CPU 80 are provided at the distal end portion 26 of the electronic endoscope 12. Is provided.

  The TG 78 generates a driving pulse (vertical / horizontal scanning pulse, reset pulse, etc.) for the solid-state imaging device 58 and a synchronization pulse for the AFE 72 based on the control of the CPU 80. The solid-state imaging device 58 is driven by a driving pulse input from the TG 78, photoelectrically converts an optical image formed on the imaging surface 58a via the objective optical system 50, and outputs it as an imaging signal.

  A large number of pixels are arranged in a matrix on the imaging surface 58a of the solid-state imaging element 58, and a photosensor (photoelectric conversion element) is provided for each pixel. Light incident on the imaging surface 58a of the solid-state imaging device 58 is accumulated as a charge in the photosensor of each pixel. The signal charge amount accumulated in the photosensor of each pixel is sequentially read out as a pixel signal by scanning in the vertical and horizontal directions by a vertical scanning circuit and a horizontal scanning circuit (both not shown), and a predetermined frame rate is obtained. Is output.

  Although not shown, the solid-state image sensor 58 is a solid-state image sensor of a single plate color imaging system provided with a color filter composed of a plurality of color segments (for example, a primary color filter with a Bayer array).

  The configuration of a signal readout circuit that reads out the accumulated charge of each photosensor of the solid-state imaging device 58 as an imaging signal is well known, and a general configuration such as a 3-transistor configuration or a 4-transistor configuration can be applied. There is no explanation here.

  The AFE 72 includes a correlated double sampling (CDS) circuit, an automatic gain circuit (AGC), and an A / D converter. The CDS circuit performs correlated double sampling processing on the imaging signal output from the solid-state imaging device 58 to remove reset noise and amplifier noise generated in the solid-state imaging device 58.

  The AGC amplifies the image signal from which noise has been removed by the CDS circuit with a gain (amplification factor) designated by the CPU 80. The A / D converter converts the imaging signal amplified by the AGC into a digital signal having a predetermined number of bits and outputs the digital signal.

  The imaging signal (digital imaging signal) digitized and output by the AFE 72 and the temperature detection signal of the solid-state imaging device 58 are input to the processor device 14 through the signal line 66.

  The processor device 14 includes a CPU 82, a ROM 84, a RAM 85, an image processing circuit (DSP) 86, and a display control circuit 88.

  The CPU 82 controls each part in the processor device 14 and controls the entire endoscope system 10 in an integrated manner. The ROM 84 stores various programs and control data for controlling the operation of the processor device 14. The RAM 85 temporarily stores programs executed by the CPU 82 and data.

  The DSP 86 performs color interpolation, color separation, color balance adjustment, gamma correction, image enhancement processing, and the like on the imaging signal input from the AFE 72 under the control of the CPU 82 to generate image data.

  The image data output from the DSP 86 is input to the display control circuit 88, and the display control circuit 88 converts the image data input from the DSP 86 into a signal format corresponding to the monitor 38 and displays it on the screen of the monitor 38.

  The operation unit 90 of the processor device 14 is provided with a mode switching button for selecting or switching the operation mode of the solid-state imaging device 58, and various buttons for receiving other user instruction inputs.

  The light source device 16 includes a light source 100, a light source driving circuit 112, and a CPU 114. The CPU 114 communicates with the CPU 82 of the processor device 14 and controls the light source driving circuit 112.

  The light source 100 is a blue laser diode in this embodiment, and is ON / OFF controlled by the light source driving circuit 112. Blue laser light emitted from the blue laser diode is introduced into the incident end of a light guide 120 configured by bundling a plurality of optical fibers.

  As described above, the phosphor 53 is provided between the emission end 120a of the light guide 120 and the tip observation window 40 of the electronic endoscope 12. The blue laser light that has passed through the light guide 120 is irradiated onto the phosphor 53 to bring the phosphor 53 into an excited state, and part of the phosphor 53 is transmitted through the phosphor 53 and emitted from the illumination window 42 as blue light.

  The phosphor 53 is excited by blue laser light and emits a wide range of light (yellow as a color) from the wavelength range per blue / green boundary to the red wavelength range in terms of the wavelength band of light. The yellow light and the blue light are mixed to become white light, and the subject is illuminated through the illumination window 42.

  The reflected light from the subject (affected part) illuminated with white light including red (R) light, blue (B) light, and green (G) light is reflected by a solid-state imaging device 58 equipped with color filters of three primary colors of RGB. By receiving light, a color image of the subject is reproduced.

  When the inside of the body cavity is observed with the endoscope system 10 configured as described above, the electronic endoscope 12, the processor device 14, the light source device 16, and the monitor 38 are turned on, and the electronic internal The insertion part 20 of the endoscope 12 is inserted into the body cavity, and the image in the body cavity imaged by the solid-state imaging device 58 is observed on the monitor 38 while illuminating the body cavity with the illumination light from the light source device 16. .

  FIGS. 5A and 5B are diagrams for explaining the basic principle of the driving method of the CMOS type solid-state imaging device 58 in the present embodiment. When the temperature of the imaging device 58 rises, further temperature rise is suppressed. It is a figure explaining the operation | movement method to do.

  The CMOS type solid-state imaging device 58 basically captures a subject as a moving image by driving a rolling shutter, and for each pixel row, the exposure period (a timing at which the reset signal 101 is applied to a certain pixel row) A time lag occurs until the read signal 102 for reading out the pixel signal of the pixel row is applied.

  In the present embodiment, as shown in FIG. 5A, one frame of the subject image is basically taken in 1/60 seconds, and 60 frames of the subject image are taken in one second. Since shooting is performed at a high frame rate of 60 frames per second, the image is not greatly distorted even if the endoscope distal end portion 26 is moved with respect to the subject. At this time, the blue laser diode (light source) 100 is photographed while continuing to emit light.

  When the light source 100 continues to emit light and the phosphor 53 continues to be irradiated with blue laser light, the temperature of the phosphor 53 rises. When observation continues for a long time, the temperature of the phosphor 53 increases, and heat is conducted to the solid-state image sensor 58 provided at a position sandwiched between the two illumination windows 42, and the temperature of the solid-state image sensor 58 is reduced. Will be raised.

  Since the solid-state image sensor 58 itself is a heat generating element, the temperature rises when observation takes a long time, and the temperature of the solid-state image sensor 58 further rises when the heat of the phosphor 53 arranged in close proximity thereto propagates. There is a risk that the noise included in the observed image cannot be ignored.

  Therefore, in this embodiment, when the detection temperature of the solid-state image sensor 58 exceeds a certain threshold temperature, the frame rate is reduced to half as shown in FIG. 5B, and 30 frames of subject images are captured per second. Change to the drive mode. Since the frame rate is halved, the amount of heat generated by the solid-state image sensor 58 is reduced, and the temperature of the solid-state image sensor 58 is lowered.

  Since the temperature of the solid-state imaging device 58 is lowered and the exposure period for each frame is doubled, the signal amount of the image of one frame is increased, and the image quality is improved as compared with 1/60 seconds. Become. In order to suppress a change in image brightness when the frame rate is switched, the AGC amplification factor in the AFE 72 may be controlled to be halved only during the switching.

  As described above, in this embodiment, when the temperature of the solid-state imaging device 58 becomes high, the frame rate is reduced from 60 frames per second to 30 frames per second. When the endoscope distal end portion 26 is moved, there is a high possibility that the image is distorted.

  When a 1-frame image is captured in 1/30 seconds, the image is not distorted when observed without moving the endoscope distal end portion 26 so much, and the imaging is simultaneous in each pixel row of the solid-state image sensor 58. Does not matter much.

  However, depending on the observation state, the endoscope distal end 26 may be moved quickly. In this case, there is a problem of image distortion due to lack of simultaneity of photographing for each pixel row. Therefore, in the present embodiment, as shown in FIG. 6B (FIG. 6A is the same as FIG. 5B), on / off control of the light source 100 is executed.

  That is, the light source 100 is turned on only for an arbitrary predetermined period in the period from the last timing of the reset signal application timing of all pixel rows to the first readout signal application timing of all pixel rows, and otherwise the light source 100 is turned on. Turns off.

  In each pixel row, light can be received during a period from the reset signal application timing to the read signal application timing. However, since the inside of the body cavity is in a dark place, signal charges are not accumulated in each pixel even if light can be received. That is, only the period during which the light source 100 is turned on is the actual “exposure period”.

  As a result, the exposure periods of all the pixel rows of the solid-state imaging device 58 are at the same timing, the simultaneity of photographing of all the pixel rows is guaranteed, and image distortion is eliminated. Compared to the exposure period of FIG. 6A, the exposure period becomes shorter and the signal amount decreases, but the AGC amplification factor in the AFE 72 may be increased accordingly.

  Further, when performing image processing, the noise removal processing is strengthened (for example, when the noise removal processing is performed once on the captured image obtained by turning on the light source 100, this noise removal processing is performed twice. It can be strengthened by repeating the process three times), and the emphasis of noise components can be suppressed by weakening the process of emphasizing contour lines and the like.

  The exposure period in FIG. 6B may be the same as the exposure period (1/60 seconds) in FIG. 5A, for example, so as to realize an image quality equivalent to the image quality in FIG. .

  Since the exposure period in FIG. 6B is shorter than the exposure period in FIG. 6A, and the extinction period in which the phosphor 53 is not irradiated with laser light is provided, the temperature of the phosphor 53 decreases, The amount of heat that propagates to the solid-state image sensor 58 also decreases. As a result, the temperature of the solid-state image sensor 58 is lowered.

  The drive modes in FIGS. 5A and 5B are switched according to the detected temperature of the solid-state image sensor 58. However, the drive modes in FIGS. 6A and 6B are switched by the endoscope. It may be performed by an operator switching instruction, or may be automatically switched to the drive mode of FIG. 6B when the CPU 82 analyzes the observation image and the movement of the image becomes a predetermined threshold value or more. .

  For example, when the endoscope system 10 is driven in the driving mode shown in FIG. 6B, the output of the light source 100 may be set to a high output to capture a high brightness image. In such a case, the observation takes a long time, and the temperature of the phosphor 53 rises to raise the temperature of the solid-state image sensor 58.

  Therefore, in such a case, in this embodiment, the endoscope system is driven in the driving mode as shown in FIG. 7B (FIG. 7A is the same as FIG. 6B) and is described above. The simultaneous imaging of each pixel row is ensured and the temperature rise of the phosphor 53 is suppressed.

  In FIG. 7B, the exposure period for capturing an image of each frame is divided into a plurality of exposure periods 103 and 104 (two in this example), and the extinction period 105 is set between the exposure periods (the laser light source on period). The phosphor 53 is cooled in the extinguishing period 105. Accordingly, it is possible to capture a high-luminance image while guaranteeing simultaneity, and it is possible to suppress an increase in temperature of the solid-state imaging device and capture a low-noise image.

  In the above-described embodiment, the solid-state imaging device using a CMOS transistor as a signal readout circuit has been described as an example. However, the signal readout circuit is not limited to a CMOS transistor, and may be another MOS transistor such as an NMOS transistor. Needless to say, the solid-state imaging device may be a MOS type solid-state imaging device. The light source 100 is not limited to a laser light source, and may be an LED light source.

  Further, in the above-described embodiment, after reducing the frame rate to a low frame rate (1/30 seconds in the embodiment), as shown in FIG. 6B, the exposure periods of all the pixel rows are synchronized. However, as shown in FIG. 5A, at the high frame rate (in the embodiment, 1/60 seconds), the exposure period of all the pixel rows may be synchronized as in FIG. 6B.

  As described above, the endoscope system and the driving method thereof according to the present embodiment have a MOS solid-state image sensor mounted at the tip and an illumination unit provided adjacent to the MOS solid-state image sensor. An endoscope that illuminates a subject in the body cavity with the illumination unit when the tip is inserted into the body cavity of the subject, and captures an image of the subject with the MOS solid-state image sensor; and the MOS solid-state image sensor And a temperature detection means for detecting the temperature of the MOS solid-state imaging device in a driving mode in which an image of the subject is output from the MOS solid-state imaging device at a first frame rate. The MOS type solid-state imaging in a drive mode in which the frame rate is set to a second frame rate lower than the first when the temperature detected by the temperature detecting means rises and reaches a threshold value while the temperature is detected. Characterized in that to drive the child.

  In addition, the endoscope system and the driving method thereof according to the embodiment are characterized in that the MOS type solid-state imaging device captures continuous images of the subject for each frame by driving a rolling shutter.

  In addition, the illumination unit of the endoscope system and the driving method thereof according to the embodiment includes a light that allows light emitted from a light source in a light source device provided outside the electronic endoscope to pass through the electronic endoscope. It is characterized by being guided to the illumination unit through a guide.

  In the endoscope system and the driving method thereof according to the embodiment, the illumination unit includes a phosphor that is excited by receiving light emitted from the light source.

  In the endoscope system and the driving method thereof according to the embodiment, the light source is controlled to be turned on / off by an instruction from the processor device, and all the pixel rows of the MOS type solid-state imaging device driven by the rolling shutter can receive light. The light source is turned on only during a predetermined period of the period.

  In addition, the endoscope system and the driving method thereof according to the embodiment are configured to amplify the captured image signal when the captured image is acquired from the MOS type solid-state image sensor while the light source is turned on only for the predetermined period. The processing is made higher than when the captured image is acquired from the MOS type solid-state imaging device with the light source always turned on.

  Further, the endoscope system and the driving method thereof according to the embodiment are configured such that when the captured image is acquired from the MOS type solid-state image sensor while the light source is turned on for the predetermined period, noise removal is performed on the captured image. The processing is strengthened as compared with a case where the light source is always turned on and a captured image is acquired from the MOS type solid-state imaging device.

  In the endoscope system and the driving method thereof according to the embodiment, the light source is a laser light source or an LED light source that emits blue light, and the phosphor emits yellow light including green and red when receiving the blue light. It is a fluorescent substance that emits light.

  According to the embodiments of the present invention described above, when the temperature of the MOS type solid-state imaging device mounted on the distal end portion of the endoscope rises, the frame rate of the image read from the solid-state imaging device is lowered and the illumination mode is further changed. As a result, image distortion due to the guarantee of simultaneity of photographing is avoided and the temperature is lowered, so that a low-noise subject image can be obtained.

  The endoscope system according to the present invention is useful as an endoscope system capable of capturing a high-quality image because it can acquire a low-noise captured image by suppressing the temperature rise of the MOS type solid-state imaging device. .

DESCRIPTION OF SYMBOLS 10 Endoscope system 12 Electronic endoscope 14 Processor apparatus 16 Light source apparatus 26 Tip part 26a Tip part tip surface 40 Observation window 42 Illumination window 53 Phosphor 54 Image sensor chip 55 Temperature sensor 58 Solid-state image sensor 100 Light source 120 Light guide 120a Light guide exit end

Claims (16)

A MOS-type solid-state imaging device is mounted at the distal end, and an illumination unit is provided adjacent to the MOS solid-state imaging device. When the distal end is inserted into the body cavity of the subject, the subject in the body cavity is illuminated. An electronic endoscope that illuminates at a portion and shoots an image of the subject with the MOS type solid-state imaging device;
Temperature detecting means for detecting the temperature of the MOS type solid-state imaging device;
While the MOS solid-state image sensor is being driven in the drive mode in which the image of the subject is output from the MOS solid-state image sensor at the first frame rate, the temperature detected by the temperature detecting means rises to the threshold value. An endoscope system comprising: a processor device that drives the MOS type solid-state imaging device in a driving mode in which the frame rate is set to a second frame rate lower than the first frame rate when reached.   2. The endoscope system according to claim 1, wherein the MOS type solid-state imaging device is configured to capture a continuous image of the subject for each frame by driving a rolling shutter.   3. The endoscope system according to claim 2, wherein the illuminating unit inserts light emitted from a light source in a light source device provided outside the electronic endoscope into the electronic endoscope. An endoscope system configured to be guided to the illumination unit through a guide.   The endoscope system according to claim 3, wherein the illumination unit includes a phosphor that is excited by receiving light emitted from the light source.   5. The endoscope system according to claim 4, wherein the light source is on / off controlled by an instruction from the processor device, and all the pixel rows of the MOS type solid-state imaging device driven by the rolling shutter are in a light receiving state. An endoscope system in which the light source is turned on only for a predetermined period of time.   6. The endoscope system according to claim 5, wherein when the light source is turned on for the predetermined period and a captured image is acquired from the MOS type solid-state image sensor, an amplification process is performed on the captured image signal. Endoscope system in which the above-mentioned light source is always turned on and is made higher than when a captured image is acquired from the MOS type solid-state imaging device.   The endoscope system according to claim 5 or 6, wherein when the light source is turned on only during the predetermined period and a captured image is acquired from the MOS solid-state imaging device, the captured image is An endoscope system in which noise removal processing to be performed is made stronger than in a case where a captured image is acquired from the MOS type solid-state imaging device with the light source always turned on.   The endoscope system according to any one of claims 5 to 7, wherein the light source is a laser light source or an LED light source that emits blue light, and the phosphor receives the blue light. An endoscope system that is a phosphor that emits yellow light including green and red. A MOS-type solid-state imaging device is mounted at the distal end, and an illumination unit is provided adjacent to the MOS solid-state imaging device. When the distal end is inserted into the body cavity of the subject, the subject in the body cavity is illuminated. An electronic endoscope that illuminates at a portion and shoots an image of the subject with the MOS type solid-state imaging device;
A method for driving an endoscope system comprising temperature detecting means for detecting the temperature of the MOS type solid-state imaging device,
While the MOS solid-state image sensor is being driven in the drive mode in which the image of the subject is output from the MOS solid-state image sensor at the first frame rate, the temperature detected by the temperature detecting means rises to the threshold value. An endoscope system driving method for driving the MOS type solid-state imaging device in a driving mode in which the frame rate is set to a second frame rate lower than the first frame rate when reaching.   10. The driving method for an endoscope system according to claim 9, wherein the MOS type solid-state imaging device is configured to take a continuous image of the subject for each frame by driving a rolling shutter.   The driving method of an endoscope system according to claim 10, wherein the illuminating unit transmits light emitted from a light source in a light source device provided outside the electronic endoscope through the electronic endoscope. A driving method of an endoscope system configured to be guided to the illumination unit through a light guide to be inserted.   The method for driving an endoscope system according to claim 11, wherein the illumination unit includes a phosphor that is excited by receiving light emitted from the light source.   13. The method for driving an endoscope system according to claim 12, wherein the light source is controlled to be turned on / off by an instruction from the processor device, and all pixel rows of the MOS type solid-state imaging device driven by the rolling shutter can receive light. A driving method of an endoscope system in which the light source is turned on only for a predetermined period in a period in a state.   14. The method for driving an endoscope system according to claim 13, wherein when a captured image is acquired from the MOS type solid-state imaging device while the light source is turned on only for the predetermined period, the captured image signal is output. A method for driving an endoscope system, wherein the amplification processing to be performed is made higher than in a case where a captured image is acquired from the MOS type solid-state imaging device while the light source is always turned on.   15. The method for driving an endoscope system according to claim 13 or 14, wherein when the light source is turned on for the predetermined period and a captured image is acquired from the MOS type solid-state imaging device, the captured image is displayed. The driving method of the endoscope system in which the noise removal processing performed on is strengthened as compared with the case where the light source is always turned on and the captured image is acquired from the MOS type solid-state imaging device.   The driving method of the endoscope system according to any one of claims 13 to 15, wherein the light source is a laser light source or an LED light source that emits blue light, and the phosphor emits the blue light. A driving method of an endoscope system, which is a phosphor that emits yellow light including green and red when received.

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