JP2017099455A - Endoscope system and control method of the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an endoscope system which includes a CMOS-type imaging element for reading out a signal by one pixel array in order and a semiconductor light source and which can obtain sufficient light amount, and a control method of the same.SOLUTION: A light source part includes a first light source on which a plurality of first semiconductor light-emitting elements emitting a first light are provided. An endoscope includes a CMOS-type imaging element in which a plurality of pixel arrays are configured and which reads out a signal by one pixel array in order. An image control part drives the CMOS-type imaging element per a frame period T, and performs a read-out of a signal by one pixel array in order within each of the frame period T. A light source control part turns off light of the plurality of first semiconductor light-emitting elements during a signal read-out period (t3 - t0) of the CMOS-type imaging element, and turns on the light by applying a drive current of a non-linear region to at least one of the plurality of first semiconductor light-emitting elements during a light receivable period (t1 - t3) in which the plurality of pixel arrays can receive light.SELECTED DRAWING: Figure 17

Description

  The present invention relates to an endoscope system and a control method thereof.

  In recent medical treatments, diagnosis using an endoscope system including an electronic endoscope (hereinafter referred to as an endoscope), an endoscope light source device (hereinafter referred to as a light source device), and a processor device is widely performed. It has been broken. The light source device generates illumination light. The endoscope is supplied with illumination light from the light source device, and irradiates the specimen with the illumination light from the tip. In addition, the endoscope captures an image of the inside of the specimen irradiated with the illumination light with an imaging element built in the distal end portion, and generates an imaging signal. The processor device performs image processing on the imaging signal generated by the endoscope, and generates an observation image to be displayed on the monitor.

  In a conventional endoscope system, a CCD (Charge Coupled Device) type image pickup device is used as an image pickup device of an endoscope. In recent years, a CMOS (Complementary Metal-Oxide Semiconductor) type image pickup device is being used. Yes (see Patent Document 1). In general, a CMOS type image sensor employs a rolling shutter system in which a plurality of pixel rows configured in an image pickup unit sequentially read out signals for each pixel row.

  In the rolling shutter system, since the exposure timing is sequentially shifted for each pixel row, it is necessary to control the turning on and off of illumination light in order to ensure so-called synchronism. Specifically, the simultaneity is ensured by turning off the illumination light during the signal readout period and turning on the illumination light during the other periods.

  In addition, a light source device has conventionally used a lamp light source such as a xenon lamp or a halogen lamp that emits white light as illumination light. Recently, a laser diode that emits light of a specific color instead of a lamp light source. Semiconductor light sources such as LD (Laser diode) and light emitting diodes (LED) are being used (see Patent Document 2).

  However, since the brightness of the semiconductor light source is lower than that of the lamp light source, higher brightness is desired. In a semiconductor light source, white light is generated by mixing light of at least three colors of red light, green light, and blue light. Among these, green light is the most attributed to luminance, so green light It has been proposed to increase the amount of light (see, for example, Patent Document 3). In Patent Document 3, a blue laser light source and a green phosphor are provided, and the amount of green light is increased by exciting the green phosphor with blue laser light.

JP 2013-174905 A JP 2013-042854 A JP 2013-215435 A

  As described in Patent Document 1, when a rolling shutter type CMOS image sensor is used as an image sensor of an endoscope, it is necessary to provide an extinguishing period in which illumination light is extinguished to ensure simultaneity. It is necessary to shorten the emission time of the illumination light for the extinguishing period. When driving a CMOS image sensor at a high frame rate, it is necessary to set the light emission time shorter.

  However, in an endoscope system using a rolling shutter CMOS image sensor, when a semiconductor light source is used as described in Patent Document 2, it is necessary to set the light emission intensity of the semiconductor light source to be short and to set the light emission time short. As a result, sufficient light quantity cannot be obtained. As described in Patent Document 3, an increase in the amount of green light is desired. However, in an endoscope system using a rolling shutter type CMOS image sensor and a semiconductor light source, a sufficient amount of light cannot be obtained. is the current situation.

  In addition, when a plurality of semiconductor light sources having different colors are sequentially turned on within one frame period (time-division lighting), it is necessary to set the light emission time per semiconductor light source to be shorter, so that the amount of light is further insufficient. There is a problem.

  An object of the present invention is to provide an endoscope system and a control method therefor that include a CMOS type image pickup device that sequentially reads out signals for each pixel row and a semiconductor light source, and that can obtain a sufficient amount of light. To do.

  In order to achieve the above object, an endoscope system according to the present invention includes a light source unit, an endoscope, an imaging control unit, and a light source control unit. The light source unit includes a first light source provided with a plurality of first semiconductor light emitting elements that emit first light. The endoscope includes a CMOS type imaging device that includes a plurality of pixel rows and sequentially reads out signals for each pixel row. The imaging control unit drives the CMOS image sensor for each frame period, and sequentially reads out signals for each pixel row within each frame period. The light source control unit turns off the plurality of first semiconductor light emitting elements during the signal readout period in which the signal readout of the CMOS image sensor is performed, and the plurality of first semiconductor light emission during the light receiving period in which the plurality of pixel rows can receive light. Light is applied to at least one first semiconductor light emitting element among the elements by applying a driving current in a non-linear region in which the relationship between the light emission intensity and the driving current is non-linear.

  The light source controller preferably controls the amount of light emitted from the first light source by controlling the application time of the drive current.

  The light source control unit applies a driving current in a non-linear region to at least one first semiconductor light emitting element among the plurality of first semiconductor light emitting elements, and applies a current in a linear region to at least one other first semiconductor light emitting element. It is preferable to apply.

  The light source control unit has a setting table in which setting values of driving currents for the plurality of first semiconductor light emitting elements are stored, and the light source control unit supplies driving currents to the plurality of first semiconductor light emitting elements based on the setting values stored in the setting tables. Is preferably applied.

  It is preferable that a setting value is stored in the setting table for each type of endoscope.

  The endoscope has an identification information storage unit that stores identification information indicating the type of endoscope, and the light source control unit is based on a setting value selected from a setting table according to the type of endoscope. Thus, it is preferable to apply a driving current to the plurality of first semiconductor light emitting elements.

  The imaging control unit preferably shortens the frame period and increases the frame rate when the application time is shorter than the predetermined time.

  The light source unit includes a second light source that emits light having a color different from that of the first light source, and the light source control unit illuminates light by lighting the first light source and the second light source in a time-division manner within one frame period. Is preferably generated.

  It is preferable that the imaging control unit resets the CMOS imaging device immediately before the start of illumination light generation within one frame period.

  According to an endoscope system control method of the present invention, a light source unit having a first light source provided with a plurality of first semiconductor light emitting elements that emit first light and a plurality of pixel rows are configured, and each pixel row is sequentially arranged. In a control method of an endoscope system including an endoscope having a CMOS image sensor that performs signal readout, the CMOS image sensor is driven every frame period, and signals are sequentially read out by one pixel row within each frame period. The plurality of first semiconductor light emitting elements are turned off during the signal readout period in which the signal readout of the CMOS image sensor is performed, and the plurality of first semiconductor light emitting elements are received during the light receiving period in which the plurality of pixel rows can receive light. The at least one first semiconductor light emitting element is lit by applying a driving current in a non-linear region where the relationship between the light emission intensity and the driving current is non-linear.

  According to the present invention, the light source unit includes the first light source provided with the plurality of first semiconductor light emitting elements that emit the first light, and the light source control unit reads the signal of the CMOS image sensor. The plurality of first semiconductor light emitting elements are turned off during the period, and the light emission intensity and driving are applied to at least one first semiconductor light emitting element among the plurality of first semiconductor light emitting elements during the light receiving period in which the plurality of pixel rows can receive light. Since lighting is performed by applying a driving current in a nonlinear region in which the relationship with the current is nonlinear, a sufficient amount of light can be obtained.

It is an external view of an endoscope system. It is a front view of the front-end | tip part of an endoscope. It is a figure which shows the structure of a light guide and a light guide rod. It is a block diagram which shows the electric constitution of an endoscope system. It is a figure which shows the structure of a CMOS type image pick-up element. It is a figure which shows the structure of a color filter array. It is a graph which shows the light transmittance of a color filter. It is a figure which shows the circuit structure of a pixel. It is a figure which shows the structure of a light source part. It is a graph which shows the wavelength spectrum of illumination light. It is a figure which shows the structure of a 1st light source. It is a graph which shows the spectral wavelength characteristic of the filter for narrow band light observation. It is a graph which shows the characteristic of the emitted light intensity with respect to the drive current of a LED chip. It is a figure which shows an example of a setting table. It is a figure which shows arrangement | positioning of a 1st LED chip. It is a figure which shows the relationship between the drive current with respect to four 1st LED chips, and total light emission intensity. It is a figure which shows the light emission and imaging timing in narrow band light observation mode. It is a figure which shows the light emission and imaging timing at the time of the largest light emission in narrow band light observation mode. It is a figure which shows the light emission and imaging timing in normal light observation mode. It is a figure which shows the modification of light emission and an imaging timing. It is a figure which shows the example which offset the center of the light emission surface of a 1st light source with respect to the optical axis of a condensing optical system. It is a figure which shows the modification of the relationship between the drive current with respect to four 1st LED chips, and total light emission intensity.

  In FIG. 1, an endoscope system 10 includes an electronic endoscope (hereinafter simply referred to as an endoscope) 11 that images an observation site in a living body as a specimen, and an observation site based on an imaging signal obtained by imaging. A processor device 12 that generates a display image, an endoscope light source device (hereinafter simply referred to as a light source device) 13 that supplies illumination light for irradiating an observation site to the endoscope 11, and a monitor 14 that displays the display image It has. An operation input unit 15 such as a keyboard or a mouse is connected to the processor device 12.

  The endoscope 11 includes an insertion unit 16 to be inserted into a living body (digestive organ and bronchus), an operation unit 17 provided at a proximal end portion of the insertion unit 16, and the endoscope 11 to a processor device 12 and a light source. And a universal cord 18 for connection to the device 13. The insertion part 16 is comprised by the front-end | tip part 19, the bending part 20, and the flexible tube part 21, and is connected in this order from the front end side.

  As shown in FIG. 2, two illumination windows 22 that irradiate the observation site with illumination light, an observation window 23 for capturing an image of the observation site, and the observation window 23 are washed on the distal end surface of the distal end portion 19. Therefore, an air supply / water supply nozzle 24 for supplying air and water and a forceps outlet 25 for performing various treatments by projecting a treatment tool such as a forceps or an electric knife are provided. A CMOS image sensor 35 (see FIG. 4) is built in the back of the observation window 23.

  The bending portion 20 is composed of a plurality of connected bending pieces, and bends in the vertical and horizontal directions according to the operation of the angle knob 26 of the operation portion 17. By curving the bending portion 20, the distal end portion 19 is directed in a desired direction. The flexible tube portion 21 has flexibility and can be inserted into a tortuous tube passage such as an esophagus or an intestine. A signal cable (not shown), a light guide rod 32 and a light guide 33 (see FIG. 4) are inserted through the insertion portion 16. The signal cable transmits a drive signal for driving the CMOS image sensor 35 and an image signal output from the CMOS image sensor 35. The light guide rod 32 and the light guide 33 guide the illumination light supplied from the light source device 13 to the illumination window 22. The light guide rod is also referred to as a light pipe.

  In addition to the angle knob 26, the operation unit 17 includes a forceps port 27 for inserting a treatment instrument, an air / water supply button 28 that is operated when air / water is supplied from the air / water supply nozzle 24, a still image. A freeze button (not shown) or the like is provided for photographing the image.

  A communication cable extending from the insertion portion 16, a light guide rod 32, and a light guide 33 are inserted into the universal cord 18, and a connector 29 is attached to one end of the processor device 12 and the light source device 13. ing. The connector 29 is a composite type connector composed of a communication connector 29a and a light source connector 29b. The communication connector 29a and the light source connector 29b are detachably connected to the processor device 12 and the light source device 13, respectively. One end of a communication cable is disposed on the communication connector 29a. A light guide rod 32 is disposed on the light source connector 29b.

  In FIG. 3, the light guide rod 32 is disposed on the light source device 13 side of the light guide 33. The incident end surface 32 a of the light guide rod 32 is a light incident surface (hereinafter, referred to as a light incident surface 32 a) on which illumination light emitted from the light source device 13 is incident. The light guide rod 32 is formed of a solid transparent material (transparent resin material such as polycarbonate or transparent glass). The light guide rod 32 has a cylindrical shape, and its cross-sectional shape orthogonal to the central optical path L1 is circular. That is, the shape of the light incident surface 32a is a circle. Here, the central optical path L1 indicates the central axis of the optical path of light propagating in the light guide rod 32 (that is, the central axis of the light guide rod 32).

  The light guide 33 is a fiber bundle in which a plurality of optical fibers 34 are bundled, and the cross-sectional shape orthogonal to the central optical path L2 is circular. The light guide 33 includes hundreds to thousands of optical fibers 34. The exit end face 32b of the light guide rod 32 and the entrance end face 33a of the light guide 33 are optically joined in a state of facing each other. The central optical path L1 of the light guide rod 32 and the central optical path L2 of the light guide 33 are substantially coincident. Here, “optically bonded” means that the light guide rod 32 and the light guide 33 are held in contact with each other, or the light guide rod 32 and the light guide 33 are made of a transparent adhesive. The state where it is joined using. Here, the central optical path L2 indicates the central axis of the optical path of light propagating through the light guide 33 (that is, the central axis of the light guide 33).

  The diameter (cross-sectional diameter) D1 of the light guide rod 32 and the diameter (cross-sectional diameter) D2 of the light guide 33 are set so as to satisfy the relationship D1 ≧ D2. That is, the exit end face 32 b of the light guide rod 32 covers the incident end face 33 a of the light guide 33. This is because uniform light is supplied from the light guide rod 32 to each optical fiber 34 of the light guide 33.

  The light guide 33 is branched into two on the exit end face side opposite to the entrance end face 33a so as to guide the light to the two illumination windows 22, respectively.

  The endoscope 11 configured as described above differs in the outer diameter of the insertion portion 16, the diameter D1 of the light guide rod 32, the diameter D2 of the light guide 33, and the like depending on the type. A plurality of types of endoscopes 11 can be connected to the light source device 13. Examples of the endoscope 11 include an upper digestive organ endoscope, a lower digestive organ endoscope, and a bronchoscope.

  The arrangement of the illumination window 22, the observation window 23, the air / water supply nozzle 24, and the forceps outlet 25 illustrated in FIG. 2 is an example of an endoscope 11. The arrangement of the illumination window 22, the observation window 23, the air / water supply nozzle 24, and the forceps outlet 25 and the number of the illumination windows 22 differ depending on the type of the endoscope 11.

  4, the processor device 12 is provided with an endoscope connecting portion 12a to which a communication connector 29a of the endoscope 11 is detachably connected. The light source device 13 is provided with an endoscope connecting portion 13a to which a light source connector 29b of the endoscope 11 is detachably connected.

  The light source device 13 includes a light source unit 30 and a light source control unit 31. The light source unit 30 generates and outputs illumination light based on the control of the light source control unit 31. The illumination light output from the light source unit 30 enters the light incident surface 32a of the light source connector 29b of the endoscope 11 connected to the endoscope connection unit 13a.

  The endoscope 11 includes a light guide rod 32, a light guide 33, a CMOS type image pickup device 35, an image pickup drive unit 36, an irradiation lens 37, an objective optical system 38, and an identification information storage unit 39. ing. When the light source connector 29 b is connected to the endoscope connecting portion 13 a, the incident end surface (light incident surface) 32 a of the light guide rod 32 disposed on the light source connector 29 b faces the emission end of the light source unit 30.

  The irradiation lens 37 is arranged corresponding to each illumination window 22. The illumination light supplied from the light source device 13 is guided to each irradiation lens 37 via the light guide rod 32 and the light guide 33. The irradiation lens 37 is a concave lens and irradiates the illumination light emitted from the light guide 33 to a wide range of the observation site via the illumination window 22.

  The objective optical system 38 is disposed corresponding to the observation window 23. The CMOS image sensor 35 is disposed corresponding to the objective optical system 38. The optical image (reflected light) of the observation region irradiated with the illumination light is incident on the objective optical system 38 through the observation window 23 and is imaged on the imaging surface 35 a of the CMOS image sensor 35 by the objective optical system 38.

  The CMOS image sensor 35 is a simultaneous color sensor, and receives the return light from the observation target irradiated with the illumination light and outputs an image signal. The CMOS image sensor 35 can receive light for each of blue (B), green (G), and red (R) colors, and can change the light receiving period for each color. The CMOS image sensor 35 outputs an RGB image signal composed of a B pixel signal, a G pixel signal, and an R pixel signal as an image signal.

  The identification information storage unit 39 stores identification information including type information indicating the type of the endoscope 11 and usable examination item information. Here, the type information includes information representing the diameter D1 of the light guide rod 32. The identification information storage unit 39 is read by the controller 40 in the processor device 12 when the endoscope 11 is connected to the processor device 12.

  The processor device 12 includes a controller 40 as a control unit, a DSP (Digital signal processor) 41, a frame memory 42, an image processing unit 43, and a display control unit 44. The controller 40 includes a CPU (Central Processing Unit), a ROM (Read-only memory) that stores control programs and setting data necessary for control, a RAM (Random-access memory) as a working memory for loading the control programs, and the like. And the CPU executes the control program to control each unit of the processor device 12, the light source control unit 31, and the imaging drive unit 36. The controller 40 also functions as an imaging control unit.

  The controller 40 drives the CMOS image sensor 35 periodically (every frame period). The DSP 41 performs signal processing such as pixel interpolation processing, gamma correction, and white balance correction on the image pickup signal input from the CMOS image pickup device 35 in the endoscope 11 via the communication connector 29a. In the pixel interpolation processing, pixel interpolation processing is performed for each of the R signal, the G signal, and the B signal. The DSP 41 causes the frame memory 42 to store the imaged signal subjected to signal processing as image data for each frame period.

  The DSP 41 has a function of calculating the amount of light incident on the CMOS image sensor 35 based on the image signal input from the CMOS image sensor 35. For example, the DSP 41 calculates a luminance value for each pixel based on an R signal, a G signal, and a B signal, and calculates an incident light amount based on an integrated value obtained by integrating the luminance values over all the pixels.

  The image processing unit 43 reads image data from the frame memory 42, performs predetermined image processing, and generates an observation image. The display control unit 44 converts the image generated by the image processing unit 43 into a video signal such as a composite signal or a component signal and outputs the video signal to the monitor 14.

  In FIG. 5, a CMOS image sensor 35 includes a pixel array unit 50, a readout scanning circuit 51, a reset scanning circuit 52, a column ADC (Analog-to-digital converter) circuit 53, a line memory 54, and column scanning. A circuit 55 and a timing generator (TG) 56 are included. The TG 56 generates a timing signal based on an imaging control signal input from the controller 40 of the processor device 12 and controls each unit.

  The pixel array unit 50 includes a plurality of pixels 50a two-dimensionally arranged in a matrix in the row direction (X direction) and the column direction (Y direction), and is provided on the imaging surface 35a. In the pixel array unit 50, a row selection line LS and a row reset line LR are arranged along the row direction, and a column signal line LV is arranged along the column direction.

  The row selection line LS and the row reset line LR are provided for each pixel row. The column signal line LV is provided for each pixel column. Here, the pixel row refers to one row of pixels 50a arranged in the row direction. The pixel column refers to one column of pixels 50a arranged in the column direction.

  As shown in FIG. 6, a color filter array 58 is provided on the light incident side of the pixel array unit 50. The color filter array 58 includes a green (G) filter 58a, a blue (B) filter 58b, and a red (R) filter 58c. Any one of these filters is arranged on each pixel 50a. The color array of the color filter array 58 is a Bayer array, and the G filters 58a are arranged in a checkered pattern every other pixel, and the B filter 58b and the R filter 58c are arranged in a square lattice pattern on the remaining pixels. Is arranged.

  The color filter array 58 has the spectral characteristics shown in FIG. The G filter 58a has a high light transmittance with respect to a wavelength region of about 450 to 630 nm. The B filter 58b has a high light transmittance with respect to a wavelength region of about 380 to 560 nm. The R filter 58c has a high light transmittance with respect to a wavelength region of about 580 to 760 nm.

  Hereinafter, the pixel 50a in which the G filter 58a is disposed is referred to as a G pixel, the pixel 50a in which the B filter 58b is disposed is referred to as a B pixel, and the pixel 50a in which the R filter 58c is disposed is referred to as an R pixel. B pixels and G pixels are alternately arranged in each pixel row of even numbers (0, 2, 4,..., N−1). G pixels and R pixels are alternately arranged in each odd (1, 3, 5,..., N) pixel row. Each pixel 50a in one pixel row is commonly connected to the row selection line LS and the row reset line LR.

  As shown in FIG. 8, each pixel 50a includes a photodiode PD1, an amplifier transistor M1, a pixel selection transistor M2, and a reset transistor M3. The photodiode PD1 photoelectrically converts incident light to generate a signal charge corresponding to the amount of incident light, and accumulates it. The amplifier transistor M1 converts the signal charge accumulated in the photodiode PD1 into a voltage value (pixel signal). The pixel selection transistor M2 is controlled by the row selection line LS, and outputs the pixel signal generated by the amplifier transistor M1 to the column signal line LV. The reset transistor M3 is controlled by the row reset line LR and discards (resets) the signal charge accumulated in the photodiode PD1 to the power supply line.

  The read scanning circuit 51 generates a row selection signal based on the timing signal input from the TG 56. The readout scanning circuit 51 applies a row selection signal to the row selection line LS during the signal readout operation, thereby causing the pixel signal of the pixel 50a connected to the row selection line LS to which the row selection signal is applied to be output to the column signal line LV. To output.

  The reset scanning circuit 52 generates a reset signal based on the timing signal input from the TG 56. During the reset operation, the reset scanning circuit 52 applies a reset signal to the row reset line LR, thereby resetting the pixels 50a connected to the row reset line LR to which the reset signal is applied.

  The column ADC circuit 53 receives the pixel signal output to the column signal line LV during the signal read operation. The column ADC circuit 53 includes an ADC connected to each column signal line LV, and compares the pixel signal input from each column signal line LV with a reference signal (ramp wave) that changes stepwise with time. , Converted into a digital signal and output to the line memory 54.

  The line memory 54 holds pixel signals for one row digitized by the column ADC circuit 53. The column scanning circuit 55 sequentially outputs pixel signals from the output terminal Vout by scanning the line memory 54 based on the timing signal input from the TG 56. The pixel signal for one frame output from the output terminal Vout is the aforementioned RGB image signal.

  The CMOS type image sensor 35 performs signal readout by a “sequential readout method” as a signal readout method. Specifically, the row selection signal is given to the selected row selection line LS while the row scanning line LS of each pixel row is sequentially selected by the readout scanning circuit 51. As a result, for all the pixels 50a in the pixel array unit 50, signal reading is sequentially performed for each pixel row from the first pixel row “0” to the last pixel row “N”.

  The CMOS image sensor 35 can execute a “sequential reset method” and a “batch reset method” as a reset method. In the sequential reset method, the reset signal is given to the selected row reset line LR while the row reset line LR is sequentially selected by the reset scanning circuit 52. As a result, in the sequential reset method, the reset is performed sequentially for each pixel row from the first pixel row “0” to the last pixel row “N”.

  In the collective reset method, all the row reset lines LR are selected by the reset scanning circuit 52, and a reset signal is collectively applied to all the row reset lines LR. Thereby, all the pixel rows of the pixel array unit 50 are simultaneously reset at the same time.

  Although not shown in FIG. 5, the CMOS image sensor 35 is appropriately provided with a correlated double sampling (CDS) circuit and an automatic gain control (AGC) circuit. The CDS circuit performs correlated double sampling processing on the pixel signal output from the pixel 50a to each column signal line LV. The AGC circuit performs gain adjustment on the pixel signal on which the correlated double sampling processing has been performed.

  In FIG. 9, the light source unit 30 includes a first light source 60, a second light source 61 and a third light source 62 as semiconductor light sources, and a condensing optical system 63. The first light source 60 includes four rectangular first LED chips 60a and a substrate 60b on which the first LED chips 60a are mounted. The first light source 60 is provided with a plurality of first LED chips 60a in order to increase the luminance.

  On the other hand, the second light source 61 is composed of one rectangular second LED chip 61a and a substrate 61b on which the second LED chip 61a is mounted. Similarly, the third light source 62 includes one rectangular third LED chip 62a and a substrate 62b on which the third LED chip 62a is mounted. The first to third LED chips 60a to 62a are semiconductor light emitting elements.

  The first light source 60, the second light source 61, and the third light source 62 are driven and controlled by the light source control unit 31, respectively. As shown in FIG. 10, the first LED chip 60a emits green light (first light) LG having an emission wavelength band of about 470 nm to 590 nm and a peak wavelength of about 540 nm. The second LED chip 61a emits blue light (second light) LB having an emission wavelength band of about 430 nm to 480 nm and a peak wavelength of about 455 nm. The third LED chip 62a emits red light (third light) LR having an emission wavelength band of about 580 nm to 640 nm and a peak wavelength of about 620 nm.

  The condensing optical system 63 includes first to third collimator lenses 64 to 66, a condensing lens 67, and first and second dichroic mirrors (DM) 68 and 69. The first collimator lens 64 collects the green light LG emitted from the first light source 60 and emits the collected green light LG as parallel light. The second collimator lens 65 collects the blue light LB emitted from the second light source 61 and emits the collected blue light LB as parallel light. The third collimator lens 66 condenses the red light LR emitted from the third light source 62 and emits the condensed red light LR as parallel light. Note that the light collimated by the first to third collimator lenses 64 to 66 does not have to be completely parallel light as long as it can be regarded as substantially parallel. The parallelism of the parallel light is preferably higher as the distance from the lens positions of the first to third collimator lenses 64 to 66 to the position of the condenser lens 67 is longer.

  The optical path of the green light LG emitted from the first collimator lens 64 and the optical path of the blue light LB emitted from the second collimator lens 65 are orthogonal to each other, and the first DM 68 is disposed at this intersection. The green light LG is incident on one surface of the first DM 68 at an angle of 45 °, and the blue light LB is incident on the other surface at an angle of 45 °. The first DM 68 has a threshold value between the wavelength band of the green light LG and the wavelength band of the blue light LB, transmits the green light LG, and reflects the blue light LB. Therefore, the first DM 68 integrates the optical path with the blue light LB into the optical path of the green light LG.

  The optical path of the green light LG integrated by the first DM 68 and the optical path of the red light LR emitted from the third collimator lens 66 are orthogonal to each other, and the second DM 69 is disposed at this intersection. The green light LG and the blue light LB are incident on one surface of the second DM 69 at an angle of 45 °, and the red light LR is incident on the other surface at an angle of 45 °. The second DM 69 has a threshold between the wavelength band of the red light LR and the wavelength band of the green light LG, transmits the green light LG and the blue light LB, and reflects the red light LR. Therefore, the second DM 69 integrates the optical path of the red light LR into the optical path of the green light LG and the blue light LB.

  The green light LG, the blue light LB, and the red light LR emitted from the second DM 69 are incident on the condenser lens 67 as illumination light. The condensing lens 67 condenses the incident illumination light on the region R1 including the light incident surface 32a of the endoscope 11 connected to the endoscope connecting portion 13a. The optical axis Lc of the condensing optical system 63 is set so as to substantially coincide with the center (center optical path L1) of the light incident surface 32a. Therefore, the condensing optical system 63 aligns the optical axis Lc with the center of the light incident surface 32a, and condenses the illumination light in the region R1 including the light incident surface 32a. Note that the center of the first collimator lens 64 coincides with the optical axis Lc of the condensing optical system 63.

  Since the region R1 is a region onto which the light image of the light emitted from each of the first light source 60, the second light source 61, and the third light source 62 is projected by the condensing optical system 63, hereinafter, the projection region R1. Call it.

  The projection region R1 is larger than the light incident surface 32a of the endoscope 11 having the largest diameter D1 of the light guide rod 32 among the endoscopes 11 that can be connected to the endoscope connecting portion 13a. That is, the condensing optical system 63 causes the illumination light to enter the projection region R1 including the light incident surfaces 32a of all types of endoscopes 11 that can be connected to the endoscope connecting portion 13a.

  In FIG. 11, the four first LED chips 60a included in the first light source 60 have the same shape and are arranged in a two-dimensional array on the substrate 60b. Specifically, two first LED chips 60a are arranged in each of the row direction (X direction) and the column direction (Y direction) orthogonal to the optical axis Lc of the condensing optical system 63 and orthogonal to each other. . The light emitting surface (first light emitting surface) 60c of the first light source 60 is composed of four first LED chips 60a arranged in a two-dimensional array. The light axis 60 is orthogonal to the light emitting surface 60c.

  The four first LED chips 60a are arranged as much as possible, but there is a slight gap between the two first LED chips 60a adjacent in the row direction and the column direction. Moreover, even if it mounts so that the clearance gap between the adjacent 1st LED chips 60a may be eliminated completely, since the peripheral part of the 1st LED chip 60a does not light-emit, in the light emission surface 60c, two adjacent 1st LED chips 60a of A non-light-emitting zone B where no green light LG is emitted is generated at the boundary. In the present embodiment, since the first LED chip 60a has a “2 × 2” two-dimensional array arrangement, the non-light-emitting band B occurs in a cross shape. Note that the non-light emission band B is not limited to a region where the green light LG is completely zero, but also includes a region where the amount of light is lower than the surroundings.

  In the present embodiment, the first light source 60 is arranged in a state where the center Ac of the light emitting surface 60 c coincides with the optical axis Lc of the condensing optical system 63. The light image of the green light LG condensed from the condensing region R2 in the light emitting surface 60c is projected to the projection region R1 located on the light incident surface 32a after being approximately equal or enlarged by the condensing optical system 63. .

  Since the second light source 61 has only one second LED chip 61a, as shown in FIG. 9, the center of the light emitting surface (second light emitting surface) 61c of the second light source 61 is that of the condensing optical system 63. It arrange | positions so that it may correspond with the optical axis Lc. Similarly, the third light source 62 is arranged so that the center of the light emitting surface (third light emitting surface) 62 c coincides with the optical axis Lc of the condensing optical system 63.

  In the condensing optical system 63, a movable narrowband light observation filter 70 is disposed between the second DM 69 and the condensing lens 67. The narrowband light observation filter 70 is inserted into and removed from the optical path between the second DM 69 and the condenser lens 67 by a drive unit (not shown). The drive control of the narrowband light observation filter 70 is performed by the light source control unit 31.

  The endoscope system 10 is capable of a normal light observation mode and a narrow band light observation mode. The narrowband light observation filter 70 is detached from the optical path in the normal light observation mode, and is inserted on the optical path in the narrowband light observation mode. The normal light observation mode is a normal observation mode in which imaging is performed by irradiating the observation site with broadband light as illumination light. The narrow-band light observation mode is a special observation mode in which imaging is performed by irradiating an observation site with narrow-band light as illumination light. The narrow-band light observation mode is used for observing microvessels on the mucosal surface layer.

As shown in FIG. 12, the narrowband light observation filter 70 includes a first transmission band part TB1 and a second transmission band part TB2. The first transmission band portion TB1 is a wavelength band having a wavelength equal to or less than the first wavelength λ ₁ and has a light transmittance of almost 100%. The second transmission band portion TB2 is a wavelength band having a wavelength not less than the second wavelength λ _{2 and not} more than the third wavelength λ ₃ , and has a light transmittance of almost 100%. In the wavelength bands other than the first transmission band part TB1 and the second transmission band part TB2, the light transmittance is almost 0%. In this embodiment, λ ₁ = 450 nm, λ ₂ = 530 nm, and λ ₃ = 550 nm.

  The first transmission band section TB1 transmits blue components having a wavelength of 450 nm or less from the blue light LB to generate blue narrow band light NLB. The second transmission band unit TB2 transmits a part of the wavelength components (components having a wavelength of 530 to 550 nm) from the green light LG to generate the green narrowband light NLG.

The light source control unit 31 controls the emission intensity of each of the first light source 60, the second light source 61, and the third light source 62 based on the control of the controller 40. Each of the first to third LED chips 60 a to 62 a emits light when a drive current is applied by the light source control unit 31. As shown in FIG. 13, there are a linear region LR and a nonlinear region NR in the characteristics of the emission intensity of each of the first to third LED chips 60a to 62a with respect to the drive current. The linear region LR is a region below the predetermined current I _TH , and the nonlinear region NR is a region larger than the predetermined drive current I _TH . In the linear region LR, the relationship between the emission intensity and the drive current is linear. In the non-linear region NR, the relationship between the light emission intensity and the drive current is non-linear. Further, in the non-linear region NR, the amount of increase in light emission intensity with respect to the amount of increase in drive current is smaller than that in the linear region LR.

  The light source control unit 31 sets a drive current to be applied to the first to third LED chips 60a to 62a according to the type of the endoscope 11 connected to the endoscope connecting unit 13a. Specifically, the controller 40 reads the identification information from the identification information storage unit 39 of the endoscope 11, and based on the read identification information, generates a drive current that can obtain a light emission intensity suitable for each type of the endoscope 11. The light source controller 31 sets the first to third LED chips 60a to 62a.

  As shown in FIG. 14, the controller 40 has a setting table ST in which setting values of drive currents corresponding to the types of the endoscope 11 are stored. The controller 40 determines drive currents for the first to third LED chips 60a to 62a based on the setting table ST. The setting table ST stores a set value of the drive current for each observation mode. A setting table ST illustrated in FIG. 14 is an example of a setting table used in the narrowband light observation mode.

  For example, the lower gastrointestinal endoscope requires less light than the upper gastrointestinal endoscope, so the driving current for the lower gastrointestinal endoscope is set lower than that for the upper gastrointestinal endoscope. Has been. Similarly, since the bronchoscope requires a smaller amount of light for imaging than the lower digestive organ endoscope, the drive current for the bronchoscope is set lower than that for the lower digestive organ endoscope.

A first 2LED chip 61a included in the second light source 61, for a first 3LED chip 62a included in the third light source 62, as the drive current, on-current I _ON in the non-linear region NR as shown in FIG. 13 is applied The This on-current I _ON is stored in the setting table ST for each type of endoscope 11. In the narrow-band light observation mode, the third light source 62 is turned off. Therefore, in the setting table ST shown in FIG. 14, the setting value of the driving current of the third LED chip 62a is 0.0 A (ampere). ing.

The first light source 60, includes four first 1LED chip 60a, the at least one first 1LED chip 60a of these, on current I _ON in the non-linear region NR is applied. For example, as shown in FIG. 15, the four first LED chips 60a are distinguished from the first LED chips G1 to G4. In this case, as shown in FIG. 16, the first LED chips G1 to G4 that are selected to apply the _ON current ION in the non-linear region NR and the driving current that is set to “0” are selected. The device is driven with a drive current in the linear region LR. Thereby, the relationship between the total light emission intensity of the first light source 60 and the drive current can be made substantially linear. In this case, the on-current I _ON is approximately twice the predetermined current I _TH described above, and preferably satisfies the relationship “2L _TH > L _ON ”. Here, “L _TH ” is the emission intensity (see FIG. 13) obtained when a predetermined current I _TH is applied to one first LED chip 60a. Further, “L _ON ” is the light emission intensity (see FIG. 13) obtained when the on-current I _ON is applied to one first LED chip 60a.

Specifically, in the first region A, the drive currents of the first LED chips G3 and G4 are increased or decreased in the linear region LR in a state where the drive currents of the first LED chips G1 and G2 are both “0”. In each of the first LED chips G3 and G4, the light emission intensity changes linearly in the range of “0 to L _TH ” by changing the drive current between “0 and I _TH ”. That is, the first LED chips G3 and G4 can change the light emission intensity linearly between “0 to 2L _TH ” with respect to the drive current by a combination of both. Since the relationship of "2L _TH> L _ON", the increase or decrease of the 1LED chip G3, G4 of the drive current in the linear region LR, the total luminous intensity, in a range of "0 to L _ON", the drive current It is possible to change to linear.

In the second region B, and the 1LED chip G1 is applied an ON current I _ON, in the state in which the driving current of the 1LED chip G2 is "0", the 1LED chip G3, G4 of the drive current in each linear region LR Increase or decrease. For the same reason as described above, the total light emission intensity is changed linearly with respect to the drive current in the range of “L _{ON to} 2L _ON ” by increasing / decreasing the drive current of the first LED chips G3, G4 in the linear region LR. Is possible.

In the third region C, and it is applied together on current I _ON in the 1LED chip G1, G2, increasing or decreasing the 1LED chip G3, G4 of the drive current in each linear region LR. For the same reason as described above, the total emission intensity is changed linearly with respect to the drive current in the range of “2L _{ON to} 3L _ON ” by increasing / decreasing the drive current of the first LED chips G3, G4 in the linear region LR. Is possible.

Then, in the fourth area D, while applying together on current I _ON in the 1LED chip G1 to G3, increases or decreases the drive current of the 1LED chip G4 each linear region LR. By increasing or decreasing the drive current of the first LED chip G4 in the linear region LR, the total light emission intensity can be changed linearly with respect to the drive current in the range of “3L _{ON to} 3L _ON + L _TH ”.

  In the setting table ST described above, the drive current is stored for each of the first LED chips G1 to G4 for each type of the endoscope 11. The total light emission intensity of the first light source 60 is determined based on the relationship between the total light emission intensity and the drive current shown in FIG.

  Further, the light source control unit 31 controls the light emission timing and the light emission time of each of the first light source 60, the second light source 61, and the third light source 62 based on the control of the controller 40. The light source control unit 31 controls the emission light amounts of the first to third light sources 60 to 62 by keeping the driving current applied to the first to third LED chips 60a to 62a constant and controlling the application time of the driving current. To do.

  For example, in the narrow-band light observation mode, the light source control unit 31 controls the application time of the drive current to turn on the first light source 60 and the second light source 61 sequentially in a time division manner. The controller 40 causes the light source control unit 31 to control turning on and off of the first light source 60 and the second light source 61 in synchronization with the imaging operation of the CMOS type imaging device 35.

Specifically, as shown in FIG. 17, the first light source 60 and the second light source 61 are lit in a time-division manner within one frame period T _C of the CMOS image sensor 35, respectively, and the green narrowband light NLG Blue narrowband light NLB is generated. Note that the lighting order of the first light source 60 and the second light source 61 is not limited to this order, and may be reversed.

In the present embodiment, it is assumed that the CMOS image sensor 35 performs a reset operation by the “sequential reset method” and performs a signal read operation by the “sequential read method”. The time when signal reading is completed in a certain frame period T _C is set as the start time t0 of the subsequent frame period T _C.

The first light source 60 starts to be lit at a time t1 after a predetermined time has elapsed from the start time t0. I _G (total luminous intensity of the four first 1LED chip 60a) first luminous intensity of the light source 60 at this time corresponds to the drive current set in the first 1LED chip 60a on the basis of the setting table ST described above. Then, the first light source 60 is turned off at time t2 when a predetermined green light emission time _TG has elapsed from time t1.

  In the present embodiment, the CMOS image sensor 35 sequentially performs a reset operation by a reset method so that the reset of the last pixel row “N” is completed at time t1. That is, the reset operation is performed immediately before the start of illumination light generation.

The second light source 61 is turned on at time t2. The I _B (emission intensity of one of the first 2LED chip 61a) a second luminous intensity of the light source 61 of the case, corresponding to the driving current set to a 2LED chip 61a on the basis of the setting table ST described above. The second light source 61, a predetermined blue emission time T _B from the time t2 is turned off at time t3 has elapsed. The CMOS type image pickup device 35 performs signal readout by the “sequential readout method” from time t3. That is, the first light source 60 and the second light source 61 are turned off during the signal readout period in which the signal readout from the CMOS image sensor 35 is performed.

The above lighting and extinguishing control is repeatedly performed every frame period T _C. The period from time t1 to time t3 is the light emission period T _ON , and the other periods (t0 to t1 and t3 to t0) are the extinguishing period T _OFF . Therefore, the light emission period T _ON and the extinguishing period T _OFF are repeated during the imaging operation. As described above, the signal reading operation and the reset operation are performed during the extinguishing period T _OFF .

  The CMOS type image pickup device 35 performs the signal readout by the sequential readout method, and thus is a rolling shutter method. Since the light source 61 emits light, the exposure period during which the illumination light is actually exposed is the same for all pixel rows. Therefore, so-called simultaneity is ensured by the above-described lighting and extinguishing control.

The light source control unit 31, under control of the controller 40, depending on the amount of light entering the CMOS image sensor 35 calculated by DSP 41, changes the green light emission time T _G and the blue light emission time T _B. For example, when the incident light intensity in a certain frame period T _C is smaller than a predetermined value, the subsequent frame period T _C, together longer green light emission time T _G and the blue light emission time T _B. When changing the green light emission time T _G and the blue light emission time T _B is preferably changed while maintaining the ratio of the green light emission time T _G and the blue light emission time T _B in the same. In FIG. 17, T _G / T _B = 1 is set, but the ratio T _G / T _B is not limited to “1”.

Further, when changing the green light emission time T _G and the blue light emission time T _B, the time t3 for the start time t0 is unchanged, to change the time t1 and the time t2 with respect to the start time t0. Further, when the first light source 60 and the second light source 61 are set to the maximum light emission amounts, as shown in FIG. 18, the reset operation is sequentially performed in parallel with the signal reading operation, and the first light source 60 and the second light source 61 are immediately after the start time t0. The lighting of one light source 60 is started. In this case, the pixel row “M−1” of the previous row is reset simultaneously with the signal readout of a certain pixel row “M”.

On the other hand, in the normal light observation mode, the light source control unit 31 turns on the first light source 60, the second light source 61, and the third light source 62 sequentially in a time-division manner. Specifically, in the normal light observation mode, as shown in FIG. 19, the third light source 62, the first light source 60, and the second light source 61 are within the one frame period T _C of the CMOS image sensor 35. Time-division lighting is performed in order, and red light LR, green light LG, and blue light LB are generated.

  Since the red light LR, the green light LG, and the blue light LB are irradiated to the observation region within the exposure period of the CMOS image sensor 35, the return light from the observation region is incident on the CMOS image sensor 35. For the CMOS type image pickup device 35, it is equivalent to irradiation with white light in which red light LR, green light LG, and blue light LB are mixed. Since the lighting and extinguishing control in the normal light observation mode is the same as the lighting and extinguishing control in the narrow-band light observation mode except that the third light source 62 is lit, detailed description is omitted.

  Next, the operation of the endoscope system 10 will be described. When a user such as a doctor performs an endoscopic diagnosis, he or she selects one corresponding to the diagnosis from a plurality of types of endoscopes 11 and connects the selected endoscope 11 to the processor device 12 and the light source device 13. When the processor device 12 and the light source device 13 are powered on, the endoscope system 10 is activated.

  When the endoscope system 10 is activated, the controller 40 in the processor device 12 reads identification information from the identification information storage unit 39 of the endoscope 11. The controller 40 is a control method suitable for the type of endoscope 11 based on the read identification information, and the light emission operation of the light source unit 30, the imaging operation of the CMOS image sensor 35, and the image processing operation of the image processing unit 43. Control etc.

For example, in the narrow-band light observation mode, the first light source 60 and the second light source 61 are driven based on the control of the controller 40. At this time, a driving current based on a setting value selected from the setting table ST according to the identification information is applied to each of the first to third LED chips 60a to 62a. The first light source 60 includes four first LED chips G1 to G4, and the driving currents of the first LED chips 60a are individually set based on the setting table ST. At this time, an on-current I _ON (for example, 9.0 A) in the non-linear region NR is set to at least one first LED chip 60a.

As shown in FIG. 17, the first light source 60 and the second light source 61 are driven in synchronization with the frame period T _C of the CMOS image sensor 35. Specifically, during the period from the time t1 when the sequential reset operation of the CMOS image sensor 35 ends to the time t3 when the signal read operation starts, the first LED chip 60a and the second LED chip 61a have the above drive currents respectively predetermined. It is applied for a time and lights up in a time-sharing manner.

  In the narrowband light observation mode, the narrowband light observation filter 70 is inserted on the optical path. Accordingly, when the first light source 60 is turned on, the green narrow band light NLG is output from the light source unit 30, and when the second light source 61 is turned on, the blue narrow band light NLB is output from the light source unit 30. The green narrowband light NLG and the blue narrowband light NLB are condensed as illumination light on the projection region R1 including the light incident surface 32a of the endoscope 11. Of the illumination light collected on the projection region R1, the light corresponding to the light incident surface 32a enters the light guide rod 32 from the light incident surface 32a.

In the endoscope 11, illumination light is guided to the illumination window 22 via the light guide rod 32 and the light guide 33, and is irradiated from the illumination window 22 to the observation site. The light image (reflected light) of the observation site irradiated with the illumination light enters the CMOS image sensor 35 from the observation window 23 via the objective optical system 38. The CMOS image sensor 35 photoelectrically converts incident light every frame period T _C to generate an image signal. This imaging signal is input to the DSP 41 of the processor device 12.

The DSP 41 performs signal processing such as pixel interpolation processing, gamma correction, and white balance correction on the digital imaging signal input from the endoscope 11 in units of frames to obtain image data, and this image data is stored in the frame memory. 42 is stored. The image processing unit 43 performs predetermined image processing on the image data stored in the frame memory 42 to generate an observation image. This observation image is displayed on the monitor 14 via the display control unit 44. The observation image displayed on the monitor 14 is updated every frame period T _C.

As described above, in the CMOS type image sensor 35 that performs the signal readout operation of the sequential readout method as the image sensor, it is necessary to set the signal readout period to the extinguishing period T _OFF in order to ensure simultaneity. As a result, the ratio of the light emission period T _ON in one frame period T _C decreases, and the amount of light is insufficient. In particular, since green light is related to brightness, an increase in the amount of light is desired. In the present embodiment, four first LED chips 60a are provided in the first light source 60, and at least one of them emits light intensity. A sufficient amount of light can be obtained because it is driven by a drive current in a non-linear region NR having a large value. Thereby, the brightness of the illumination light is increased, and the brightness of the observation image is improved.

In the above embodiment, the reset operation of the CMOS image sensor 35 is sequentially performed by the reset method, but may be performed by the collective reset method instead. In this case, as shown in FIG. 20, it is preferable to perform batch reset at the start time t1 of the light emission period T _ON (that is, immediately before the start of illumination light generation).

  In the above embodiment, the first light source 60 is arranged in a state where the center Ac of the light emitting surface 60c coincides with the optical axis Lc of the condensing optical system 63, but instead, as shown in FIG. The center Ac of the light emitting surface 60c may be arranged in an offset state in the row direction and the column direction with respect to the optical axis Lc of the condensing optical system 63. In this case, the areas of the four first LED chips G1 to G4 occupying in the condensing region R2 are different.

The area of the first LED chip G1 in the condensing region R2 is A _G1 , the area of the first LED chip G2 in the condensing region R2 is A _G2 , and the area of the first LED chip G3 in the condensing region R2 is A _G3 . Assuming that the area of the first LED chip G4 in the region R2 is A _G4 , in the example shown in FIG. 21, the relationship is A _G2 > A _G3 > A _G4 > A _G1 . In this case, it is preferable that the drive current for the first LED chip G2 having the largest area in the light condensing region R2 is the non-linear region NR, and the drive current for the other first LED chips G1, G3, G4 is the linear region LR.

  The set value of the drive current in the setting table ST is preferably determined in consideration of the area ratio of the four first LED chips G1 to G4 occupying in the condensing region R2. Further, the setting value of the drive current in the setting table ST is the area ratio of the four first LED chips G1 to G4 occupying in the region projected on the light incident surface 32a of the light guide rod 32 in the light condensing region R2. It is also preferable that it is determined in consideration. This area ratio varies depending on the size of the light incident surface 32a. Since the size of the light incident surface 32 a of the light guide rod 32 varies depending on the type of the endoscope 11, the four first LED chips occupying the region projected onto the light incident surface 32 a for each type of the endoscope 11. It is preferable that the set value is determined in consideration of the area ratio of G1 to G4.

  Moreover, in the said embodiment, although the setting table ST is provided in the controller 40, it may replace with this and may be provided in the light source control part 31. FIG. In this case, the light source control unit 31 receives the identification information indicating the type of the endoscope 11 from the controller 40, extracts the set value of the drive current corresponding to the received identification information from the setting table ST, and first to first The 3LED chips 60a to 62a are driven.

  Moreover, in the said embodiment, although the total light emission intensity | strength of the 1st light source 60 is determined based on the relationship between the total light emission intensity | strength shown in FIG. 16, and a drive current, it replaces with this and the total light emission shown in FIG. You may determine based on the relationship between intensity | strength and a drive current.

Specifically, in the above embodiment, among the first 1LED chip G1 to G4, and which applies an ON current I _ON in the non-linear region NR, a drive current to select the ones to be "0", other The LED is driven by the drive current in the linear region LR. Instead, the drive current of each of the first LED chips G1 to G4 is set to ON current I _ON or “0”. That is, the drive current of the linear region LR is not applied to any of the first LED chips G1 to G4.

FIG. 22 shows a combination pattern in which the drive currents of the first LED chips G1 to G4 are turned on current I _ON or “0”. This makes it possible to change the total luminous intensity I _G of the first light source _{60, 1L ON, 2L ON,} 3L ON, and the 4 stages of 4L _ON.

In this case, the total light emission intensity I _G of the first light source 60 is set to one of 1L _ON , 2L _ON , 3L _ON , and 4L _ON . The amount of light from the first light source 60 within one frame period T _C is set by changing the green light emission time _TG . When the frame rate is high (short-time exposure), it is preferable to set the emission intensity I _G to 3L _ON or 4L _ON, and to shorten the green emission period _TG accordingly.

As described above, when the drive currents of the first LED chips G1 to G4 are set based on the relationship between the total light emission intensity and the drive current shown in FIG. 22, the on-current I _ON or “0” is set as each drive current. Therefore, the light source control unit 31 simplifies the setting control.

In the above-described embodiment, the frame period T _C is constant, but the controller 40 performs frame processing when the light emission period T _ON (that is, the drive current application time) set by the light source control unit 31 is shorter than the predetermined time. the period T _C is shortened, may be increasing the frame rate. As a result, since the light emission period T _ON is shortened, an increase in the proportion of the extinguishing period T _{OFF in} the frame period T _C is prevented, and the image quality of the observation image is improved.

  In the above embodiment, the four first LED chips 60a are provided in the first light source 60, but the number of the first LED chips 60a is not limited to “4” and may be two or more. Moreover, in the said embodiment, although only the 1st light source 60 is made into the multichip among the 1st light source 60, the 2nd light source 61, and the 3rd light source 62, Of the 2nd light source 61 and the 3rd light source 62 One or both of them may be multichiped.

  In the above embodiment, the first DM 68 has the optical characteristic of transmitting the green light LG and reflecting the blue light LB. However, the condensing optical system 63 is changed by reversing the relationship between the transmission and reflection of the first DM 68. It may be configured. In the above embodiment, the second DM 69 has the optical characteristic of transmitting the green light LG and the blue light LB and reflecting the red light LR. However, the relationship between the transmission and reflection of the second DM 69 is reversed. The condensing optical system 63 may be configured. That is, the first DM 68 only needs to transmit one of the green light LG and the blue light LB and reflect the other. The second DM 69 only needs to transmit one of the green light LG, the blue light LB, and the red light LR and reflect the other.

  In the above embodiment, in the condensing optical system 63, the optical path of the blue light LB and the optical path of the red light LR are integrated in this order into the optical path of the green light LG, but this order is reversed. The arrangement of the second light source 61, the third light source 62, the first DM 68, and the second DM 69 may be changed.

  In the above embodiment, the primary color filter array 58 is provided in the CMOS image sensor 35, but a complementary color filter array may be provided instead.

  In the above embodiment, the first light source 60, the second light source 61, and the third light source 62 are turned on in a time-sharing manner, but some or all of them may be turned on simultaneously.

  In the above embodiment, the first light source 60, the second light source 61, and the third light source 62 are provided in the light source unit 30, but the type of the light source is not limited to these, and for example, a violet light source may be further provided. good.

  In the above-described embodiment, the light source device and the processor device are separately configured, but the light source device and the processor device may be configured as one device.

DESCRIPTION OF SYMBOLS 10 Endoscope system 11 Endoscope 12 Processor apparatus 13 Light source apparatus 30 Light source part 32 Light guide rod 33 Light guide 34 Optical fiber 35 CMOS type image pick-up element 60 1st light source 60a 1st LED chip (1st semiconductor light-emitting device)
61 2nd light source 61a 2nd LED chip (2nd semiconductor light-emitting device)
62 3rd light source 62a 3rd LED chip (3rd semiconductor light-emitting device)
70 Filter for narrow band light observation

Claims (10)

A light source unit having a first light source provided with a plurality of first semiconductor light emitting elements emitting first light;
An endoscope having a CMOS type image pickup device in which a plurality of pixel rows are configured and sequentially reading out signals for each pixel row;
An imaging control unit that drives the CMOS image sensor every frame period and sequentially reads out signals one pixel row at a time in each frame period;
The plurality of first semiconductor light emitting elements are turned off during a signal readout period in which signal readout of the CMOS image sensor is performed, and the plurality of first semiconductor light emitting elements are received during a light receiving period in which the plurality of pixel rows can receive light. A light source controller that turns on at least one of the first semiconductor light emitting elements by applying a driving current in a non-linear region where the relationship between the light emission intensity and the driving current is non-linear;
An endoscope system comprising:   The endoscope system according to claim 1, wherein the light source control unit controls an emission light amount of the first light source by controlling an application time of the driving current.   The light source controller applies a driving current of the nonlinear region to at least one first semiconductor light emitting element among the plurality of first semiconductor light emitting elements, and applies to at least one other first semiconductor light emitting element. The endoscope system according to claim 2, wherein a current in a linear region is applied.   A setting table storing setting values of driving currents for the plurality of first semiconductor light emitting elements; and the light source control unit is configured to store the plurality of first semiconductors based on the setting values stored in the setting table. The endoscope system according to claim 3, wherein the driving current is applied to a light emitting element.   The endoscope system according to claim 4, wherein the setting value is stored for each type of the endoscope in the setting table.   The endoscope includes an identification information storage unit that stores identification information indicating the type of the endoscope, and the light source control unit is selected from the setting table according to the type of the endoscope. The endoscope system according to claim 5, wherein the driving current is applied to the plurality of first semiconductor light emitting elements based on the set value.   The endoscope system according to claim 6, wherein the imaging control unit shortens the frame period and increases a frame rate when the application time is shorter than a predetermined time. The light source unit includes a second light source that emits light having a color different from that of the first light source,
The endoscope according to claim 1, wherein the light source control unit generates illumination light by lighting the first light source and the second light source in a time-division manner within the one frame period. system.   The endoscope system according to claim 8, wherein the imaging control unit resets the CMOS imaging device immediately before the start of generation of the illumination light within the one frame period. Internal view having a light source unit having a first light source provided with a plurality of first semiconductor light emitting elements that emit first light, and a CMOS type image sensor in which a plurality of pixel rows are configured to sequentially read out signals for each pixel row In a control method of an endoscope system including a mirror,
The CMOS image sensor is driven every frame period, and signal readout is sequentially performed for each pixel row within each frame period.
The plurality of first semiconductor light emitting elements are turned off during a signal readout period in which signal readout of the CMOS image sensor is performed, and the plurality of first semiconductor light emitting elements are received during a light receiving period in which the plurality of pixel rows can receive light. A control method for an endoscope system in which at least one first semiconductor light emitting element is turned on by applying a driving current in a non-linear region in which the relationship between light emission intensity and driving current is non-linear.

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