Light source device and endoscope system

Abstract

In order to ensure a sufficient amount of light while avoiding the generation of distortion and artifacts caused by a rolling shutter, and unevenness in brightness and horizontal stripes are not obvious even if a change in a pulsed light-emitting organ relates to the rolling shutter, the present disclosure proposes a light source device that generates illumination light irradiated to a subject, and that provides a light source device that is capable of generating illumination light that is irradiated to the subject. The semiconductor light-emitting device includes: a semiconductor light-emitting element that emits light; and a light source control unit that generates a light-emitting profile of the semiconductor light-emitting element and drives the semiconductor light-emitting element on the basis of the light-emitting profile. The light source control unit performs: a process of dividing one frame period in an image signal acquired by the imaging element into N (N = 2m) integers; m is an integer of 2 or more); generating a light emission profile in which the light emission intensity is controlled in units of 2k (k = an integer from 0 to m) dimming sections in accordance with the target light amount during one frame; and performing dimming control of the next frame on the basis of the light emission profile (referring to Figure 7B).

Description

Technical Field

[0001] The present disclosure relates to a light source device and an endoscope system. Background Art

[0002] In a conventional endoscope device equipped with an image sensor using a rolling shutter method, simulated global exposure is performed by extinguishing a light source during a period of effective pixel reading of the image sensor (a rolling shutter period) and illuminating the light source (pulse light emission control) during other periods (a simulated global exposure period), thereby avoiding undesirable phenomena caused by the rolling shutter, such as distortion or artifacts.

[0003] On the other hand, if the light source is completely turned off during the rolling shutter period, the amount of light may be insufficient depending on the subject (the part to be observed), and a good image may not be obtained. For example, Patent Documents 1 to 3 etc. show light source control that includes a portion of the rolling shutter period in the pulse light emission period in order to eliminate the insufficient amount of light.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-182580

[0007] Patent Document 2: Japanese Patent No. 5379932

[0008] Patent Document 3: Japanese Patent No. 6239220 Summary of the invention

[0009] Technical problem to be solved by the invention

[0010] However, when the light source control as described in Patent Documents 1 to 3 is performed, uneven brightness or horizontal stripes may occur in the screen due to the difference in exposure time of each line in adjacent frames. In addition, due to the change in the pulse light emission period of each frame, there is a problem that the uneven brightness or horizontal stripes move up and down on the display screen and become dazzling. In addition, when offset light emission is performed during the rolling shutter period to eliminate insufficient light, if the offset light emission becomes stronger to a certain extent, an unnatural image may be generated, such that the long-exposure image and the high-speed exposure image are double-exposed.

[0011] The present disclosure is made in view of such a situation, and its purpose is to propose a technology that ensures a sufficient amount of light while avoiding the distortion and artifacts caused by the rolling shutter, and even if the change in the pulse light emission period involves the rolling shutter period, the brightness unevenness and horizontal stripes are not obvious.

[0012] Solutions for solving technical problems

[0013] In order to solve the above technical problems, the present embodiment proposes a light source device, which generates illumination light to irradiate a subject, and comprises: a semiconductor light emitting element, emitting light; and a light source control unit, generating a light emission profile of the semiconductor light emitting element, and driving the semiconductor light emitting element based on the light emission profile; the light source control unit performs the following processing: dividing a frame period of an image signal obtained by an imaging element into N (N=2 m m is an integer greater than 2) dimming interval; during one frame, a dimming interval of 2 is generated according to the target light amount. k A light emission profile is used to control the light emission intensity in units of a number (k=an integer from 0 to m) of dimming intervals; and a dimming control of the next frame is performed based on the light emission profile.

[0014] In addition, the present embodiment proposes an endoscope system, which inserts an endoscope device into an observation object to obtain an image of the object, and comprises: a light source device; an imaging element, which irradiates the illumination light emitted from the light source device to the object, detects the reflected light from the object and generates an image signal; and a processor, which processes the image signal to generate an image of the object and displays it on a monitor; the light source device comprises: a semiconductor light emitting element, which emits light; and a light source control unit, which generates a light emission profile of the semiconductor light emitting element and drives the semiconductor light emitting element based on the light emission profile; the light source control unit performs the following processing: divides one frame period in the image signal obtained by the imaging element into N (N=2 m m is an integer greater than 2) dimming interval; during one frame, a dimming interval of 2 is generated according to the target light amount. k A light emission profile is used to control the light emission intensity in units of a number (k=an integer from 0 to m) of dimming intervals; and a dimming control of the next frame is performed based on the light emission profile.

[0015] Further features related to the present disclosure can be seen from the description and drawings of this specification. In addition, the present disclosure will be achieved and realized through the combination of elements and various elements and the following detailed description and the embodiments in the appended claims.

[0016] The descriptions in this specification are merely typical examples and are not intended to limit the claims or application examples in any way.

[0017] Effects of the Invention

[0018] According to the present disclosure, while avoiding the generation of distortion and artifacts caused by a rolling shutter, a sufficient amount of light is ensured, and even if changes in the pulse light-emitting organ are involved in a rolling shutter period, uneven brightness and horizontal stripes can be made less noticeable. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a diagram showing an example of the overall appearance of the endoscope system according to the present embodiment.

[0020] Figure 2 It is a diagram showing an example of a schematic internal configuration of the endoscope system according to the present embodiment.

[0021] Figure 3 1 is a diagram showing an example of the internal configuration of the light source device 101 provided inside the processor 200 .

[0022] Figure 4 1011 to 1015 are diagrams showing the spectrum (wavelength characteristics) of each of the LEDs 1011 to 1015 .

[0023] Figure 5 101 and 1018 are diagrams showing characteristics of illumination light (light that illuminates an observation area) generated by allowing each LED to pass through the orthogonal prisms 1017 and 1018 .

[0024] Figure 6 This is a diagram showing an effective pixel area and an invalid area of ​​an imaging element of a rolling shutter method using a CMOS sensor as an example.

[0025] Fig. 7A FIG. 1 is a diagram for explaining an outline of a dimming control process 1 (Example 1) according to the present embodiment.

[0026] Figure 7B FIG. 2 is a diagram for explaining an overview of the dimming control process 1 (Example 1) according to the present embodiment.

[0027] Figure 8 This is a flowchart for explaining the details of the light emission profile generation process according to the dimming control process 1 (Example 1) of the present embodiment.

[0028] Fig.9A FIG. ( 1 ) is a diagram for explaining an overview of a dimming control process 2 (Example 2) according to the present embodiment.

[0029] Fig. 9B FIG. (2) is a diagram for explaining an overview of the dimming control process 2 (Example 2) of the present embodiment.

[0030] Fig.10 This is a flowchart for explaining the details of the light emission profile generation process according to the dimming control process 1 (Example 2) of the present embodiment. DETAILED DESCRIPTION

[0031] Hereinafter, an embodiment of the present disclosure will be described with reference to the accompanying drawings. In addition, below, as one embodiment of the present disclosure, an endoscope system is described as an example.

[0032] The observation target parts of the endoscope system include respiratory organs, digestive organs, etc. Examples of respiratory organs include lungs, bronchi, and ears, nose, and throat. Examples of digestive organs include large intestine, small intestine, stomach, esophagus, duodenum, uterus, and bladder. When observing the target parts as described above, it is more effective to use images that emphasize specific biological structures.

[0033] In addition, the technology disclosed in this embodiment can also be applied to the case where the light source device is provided in a processor, and can also be applied to the case where the light source device is provided in a space that is limited in volume and sealed, that is, in an endoscope device. Therefore, in this embodiment, the structure of the latter is mainly described (refer to Figure 2 ).

[0034] <Positioning of this technology>

[0035] The inventors have developed the technology disclosed in Japanese Patent Application No. 2020-179317 (filing date: October 27, 2020; Japanese Patent Application No. 2022-070310) as an association of the present technology. The earlier application discloses an intensity-time restoration process in order to avoid the scan line noise generated when switching from pulsed light to continuous light, and the double exposure image generated when controlling the luminous intensity during the rolling shutter, which responds to the change in image brightness by controlling the luminous intensity during the rolling shutter, and then gradually restores the luminous intensity to the luminous time. The intensity-time restoration process is a process of converting the luminous time into the luminous intensity while keeping the total area of ​​the luminous contour representing the cumulative value of the light amount constant in units of frames. When implementing this process, complex operations such as logarithmic operations or floating-point multiplication must be performed in units of frames, which will not be particularly inconvenient when resources such as processors are sufficient. However, if a light source device is provided on the endoscope device side, for example, the computing resources are insufficient. Therefore, although it is also considered to add resources (such as CPU, etc.) for the above-mentioned complex calculations, since the endoscope device is a closed space to ensure waterproofness, if the CPU is used to perform the above-mentioned complex calculations, it may also affect the operator's operation due to heat. In addition, it may also exceed the rated temperature of the equipment and fall into a dangerous situation. It is also considered to set up a special heat dissipation mechanism to avoid this situation, but the setting of a heat dissipation mechanism will increase the manufacturing cost of the device itself, which is not preferred. Therefore, it is expected that the dimming control will be completed by the light source control unit (FPGA) of the light source device. However, the light source control unit is different from the CPU and is not suitable for performing complex calculations, so it is necessary to simplify the calculations used for dimming control.

[0036] In view of this situation, in this embodiment, a dimming control process is described, whose computational complexity is overwhelmingly less than the above-mentioned intensity-time restoration process, and can be executed using a light source control unit (FPGA). Like the above-mentioned intensity-time restoration process, it can avoid the generation of scan line noise and double exposure images.

[0037] <Configuration of the endoscope system>

[0038] Figure 1 1 is a diagram showing an example of the overall appearance of an endoscope system according to the present embodiment. Figure 2 1 is a diagram showing an example of the schematic internal structure of an endoscope system according to the present embodiment. The endoscope system 1 includes an endoscope device (electronic endoscope) 100, a processor 200, and a monitor 300. In addition, a scope connector (hereinafter referred to as "connector") 400 is provided at the end portion on the processor side of the endoscope device 100, which includes a connector circuit related to the features of the present embodiment.

[0039] The endoscope device 100 includes a long and thin tubular insertion portion 11 inserted into a subject. The endoscope device 100 includes, for example, a light source device 101, an LCB (Light Carrying Bundle) 102 for guiding irradiation light from the light source device 101, a light distribution lens 103 provided at the emission end of the LCB 102, an image pickup unit 104 for receiving return light from an irradiated portion (observation site) via an objective lens (not shown), a drive signal processing circuit (not shown) for driving the image pickup unit 104, and a first memory (not shown).

[0040] The irradiation light from the light source device 101 is incident on the LCB 102, and propagates by repeatedly being totally reflected in the LCB 102. The irradiation light (illumination light) propagating in the LCB 102 is emitted from the exit end of the LCB 102 disposed in the front end portion 12 of the insertion portion 11, and irradiates the observation part through the light distribution lens 103. The return light from the irradiated part passes through each pixel on the light receiving surface of the imaging unit 104 through the objective lens to form an optical image.

[0041] The camera unit 104 is arranged in the front end portion 12 of the insertion portion 11, and a CMOS (Complementary Metal Oxide Semiconductor) image sensor as a rolling shutter type image sensor can be used. The camera unit 104 accumulates the optical image formed by each pixel of the light receiving surface (the return light from the living tissue) as an electric charge corresponding to the amount of light, and generates and outputs R, G, B image signals. In addition, the camera unit 104 is not limited to a CMOS image sensor, as long as it is an image sensor based on the rolling shutter method, it can also be replaced by other types of camera devices. The signal output from the camera unit 104 is processed by the scope connector circuit 401 provided in the scope connector 400, as described below.

[0042] The processor 200 is an integrated device, which includes a signal processing device for processing a signal from the endoscope device 100, and a light source device for irradiating the inside of a body cavity that cannot be reached by natural light through the endoscope device 100. In other embodiments, the signal processing device and the light source device may be configured separately. The processor 200 includes a system controller 201, a photometric unit 202, a front-stage signal processing circuit 203, a color conversion circuit 204, a rear-stage signal processing circuit 205, and a second memory 206.

[0043] The processor 200 may also include an operation panel (not shown). The operation panel may be configured in various forms. As a specific configuration of the operation panel, for example, a hardware key for each function encapsulated on the front of the processor 200, or a touch panel GUI (Graphical User Interface), a combination of a hardware key and a GUI, etc. may be considered. The operator (physician) can perform a mode switching operation described later through the operation panel.

[0044] The light metering unit 202 obtains brightness information of the image signal obtained by shooting from the gain circuit included in the color conversion circuit 204, compares it with a predetermined appropriate brightness value (for example, the information on the appropriate brightness value can be pre-stored in an internal memory of the light metering unit 202, not shown in the figure), and notifies the system controller 201 of the comparison result (whether the current brightness value is appropriate, high or low).

[0045] The system controller 201 executes various programs stored in a memory (not shown) and centrally controls the entire endoscope system 1. The system controller 201 controls the actions and timings of various circuits in the processor 200 using control signals so as to perform appropriate processing on the endoscope device 100 connected to the processor 200. In addition, the system controller 201 can be connected to the above-mentioned operation panel.

[0046] In addition, the system controller 201 receives the comparison result with the appropriate brightness value from the metering unit 202, determines whether the current exposure should be maintained, whether the exposure should be increased (including an increased level value), or whether the exposure should be reduced (including a reduced level value), and outputs it to the light source device 101 as an exposure control signal.

[0047] Furthermore, the system controller 201 changes each action of the endoscope system 1 and the parameters used for each action according to the instructions from the operator input through the operation panel. For example, when the operator selects an observation mode (mode switching operation) through the operation panel, the system controller 201 outputs a mode selection signal to the light source device 101, and the mode selection signal is used to make the light source corresponding to the observation mode emit light. As described later, as the light source device 101, for example, a plurality of LEDs (Light Emitting Diodes) each emitting light of different wavelength bands can be used (see Figure 3 When the operator selects an observation mode (e.g., normal observation mode, special light observation mode, SatO2 mode, etc.) by, for example, operating a mode selection switch provided on the processor 200, the system controller 201 generates a mode selection signal corresponding to the selected mode and provides it to the light source control unit (light source control circuit: FPGA) 1016 of the light source device 101 (see Figure 3 ). The light source control unit 1016 determines the combination of light-emitting LEDs and their intensities and light amounts based on the mode selection signal (for example, the combination of light-emitting LEDs corresponding to the mode selection signal is pre-stored in an internal memory not shown), and outputs necessary LED control signals to each of the LEDs 1011 to 1015. When each of the LEDs 1011 to 1015 emits light of each wavelength band according to the LED control signal provided from the light source control unit 1016, each emitted light is synthesized by an orthogonal prism to generate irradiation light (synthesized light).

[0048] Data communication between the endoscope device 100 and the processor 200 can use a wired electrical communication method or an optical wireless communication method.

[0049] like Figure 2 As shown, the endoscope device 100 and the processor 200 are connected via a scope connector 400. The connector 400 includes a scope connector circuit 401. In addition, in the present embodiment, the scope connector circuit 401 is provided in the scope connector 400, but it is not necessarily provided inside the scope connector 400. For example, a circuit equivalent to the scope connector circuit 401 may be provided in the connector portion on the processor 200 side or inside the processor 200.

[0050] <Internal Configuration Example of Light Source Device 101>

[0051] Figure 3 1 is a diagram showing an example of the internal configuration of a light source device 101 provided inside the endoscope device 100 , for example.

[0052] The light source device 101 includes a green LED 1011 that emits green light, a blue LED 1012 that emits blue light, a red LED 1013 that emits red light, an amber LED 1014 that emits amber light, a UV LED 1015 that emits UV light, a light source control unit 1016 that controls light emission from each of the LEDs 1011 to 1015, and orthogonal prisms 1017 and 1018.

[0053] The light source control unit 1016 may be constituted by, for example, an FPGA, and upon receiving an exposure control signal from the system controller 201, the light source control unit 1016 changes the light emission profile of each LED and performs exposure adjustment (light quantity adjustment) by controlling the light emission period and the applied current value of each LED currently emitting light (the combination of LEDs emitting light is determined according to the observation mode). For example, after the light emission profile is changed by one level, the light source control unit 1016 determines whether to change the light emission profile again to perform exposure adjustment (dimming control) based on the exposure control signal determined by the light measurement result (comparison result with the appropriate brightness value) of the light measurement unit 202.

[0054] In addition, the light source control unit 1016 determines the combination of LEDs to be emitted according to the mode selection signal, which is used to indicate the observation mode selected by the operator. At the start of the emission, the light source control unit 1016 controls the emission of each LED according to, for example, a predetermined emission profile (default emission period and drive current value), and then performs the exposure adjustment as described above.

[0055] <About each LED light source>

[0056] Figure 4 1 is a diagram showing the spectrum (wavelength characteristics) of each LED 1011 to 1015. Figure 5 101 and 1018 are diagrams showing characteristics of illumination light (light that illuminates an observation area) generated by allowing each LED to pass through the orthogonal prisms 1017 and 1018 .

[0057] The transmission wavelength of the green LED 1011 is 540nm to 575nm, the peak wavelength is 550nm, and the half-value width is 30nm. Figure 4As shown, a phosphor is mounted on the green LED 1011, and light with a transmission band of about 400nm to 780nm is emitted through the phosphor. That is, white light is actually emitted through the green LED and the phosphor, but the white light is an intermediate product, and as described later, the transmission band is narrowed by the orthogonal prism 1018, and the green light is irradiated onto the observation part. The transmission band of the blue LED 1012 is 460nm to 490nm, the peak wavelength is 456nm, and the half-value width is 21nm. The transmission band of the red LED 1013 is 630nm to 1000nm, the peak wavelength is 650nm, and the half-value width is 20nm. The transmission band of the amber LED 1014 is 600nm to 615nm, the peak wavelength is 613nm, and the half-value width is 19nm. The transmission band of the UV LED 1015 is 385nm to 425nm, the peak wavelength is 405nm, and the half-value width is 14nm.

[0058] When the various lights (white light, blue light, red light, amber light, and UV light as intermediate products) generated by the various LEDs 1011 to 1015, including the green LED 1011 equipped with a phosphor, pass through the orthogonal prisms 1017 and 1018, they become Figure 5 The observation part is irradiated with each light of the characteristics shown. In detail, the white light generated by the green LED 1011 + phosphor is limited to the transmission band by the orthogonal prism 1018 and becomes a green light of 520nm to 595nm. The blue light emitted by the blue LED 1012 is converted into a blue light of 440nm to 500nm through the orthogonal prisms 1017 and 1018. In addition, the red light emitted by the red LED 2013 is converted into a red light of 620nm to 630nm through the orthogonal prisms 1017 and 1018. The amber light emitted by the amber LED 1014 is converted into amber light of 580nm to 630nm through the orthogonal prisms 1017 and 1018. Further, the UV light emitted by the UVLED 1015 is converted into UV light of 380nm to 450nm through the orthogonal prism 1018.

[0059] <Configuration Example of Imaging Surface of Imaging Element>

[0060] Figure 6: This is a diagram showing the effective pixel area and invalid area of ​​an imaging element of a rolling shutter method using a CMOS sensor as an example. The CMOS sensor includes an effective pixel area that can be photographed and an invalid area that cannot be photographed. In addition, a part of the effective pixel area (the peripheral part) is shielded, and it actually becomes an area where the image signal cannot be obtained. In the case of shooting using such an imaging element (global exposure), various phenomena (features) appear in the captured image. In addition, in this embodiment, the period that is not displayed on the screen is set as the global exposure period, but the technical concept of this embodiment is not limited to this case.

[0061] <Basic Concept of Dimming Control Processing in This Embodiment>

[0062] In this embodiment, the light source control unit 1016 (see Figure 3 ) alone performs dimming control processing that does not generate scan line noise and double exposure images, or is not noticeable. Specifically, by dividing one frame period into N=2 m The interval of the number (power of 2: 2, 4, 8, 16, 32, 64, 128, ...) is used, and the necessary division is only the division that can be realized by the bit shift operation. It is possible to perform the dimming control processing only by the light source control unit (FPGA) 1016 without adding a CPU, thereby realizing resource saving. Here, the number of divisions during one frame is determined to be N = 2 m The width (time width) of a divided interval falls within the global exposure period. In addition, there is no upper limit to the number of divisions. In other words, even if the number of divisions is very large, the dimming control process can be implemented by displacement calculation, so the load on the light source control unit 1016 will not be too large.

[0063] <Overview of Dimming Control Process 1: Embodiment 1>

[0064] Fig. 7A and Figure 7B This is a diagram for explaining the outline of the dimming control process 1 (Example 1) according to the present embodiment.

[0065] exist Fig. 7A and Figure 7B As an example, a frame period (33.33 ms) of the imaging unit 104 (eg, CMOS sensor) driven at 30 frames per second (FPS) is divided into 32 (2 5 ) interval to perform dimming control processing. Fig. 7A and Figure 7BIn the 701st embodiment, the global exposure period 701 is equivalent to the blanking period and is used to accumulate effective charges for all pixels in the next reading operation. For example, it is set to 1.2ms. After 1.2ms from the beginning of a frame period, the remaining 32.13ms are used to perform the rolling shutter reading operation of the effective pixels (rolling shutter period 702). Depending on how the dimming control process is performed during the rolling shutter period 702, scanning line noise or double exposure images may be generated. In addition, during Fig. 7A and Figure 7B When the required light amount is 100%, the luminous intensity is set to the maximum intensity determined by the heat at the front end of the mirror body or the rated current of the light source, and the dimming control is to make all 32 intervals illuminated, that is, continuous light.

[0066] In the dimming control process of this embodiment, the light quantity is controlled (increased or decreased) based on the comparison result of the brightness cumulative value of the current image (captured image) and the target cumulative value determined (instructed) by the operator. However, even when light quantity control is required, a sudden change in light quantity (brightness) will become stressful for the operator, so the light quantity is controlled by gradually increasing or decreasing (for example, increasing or decreasing by 5% each time) so as not to cause a sudden brightness change.

[0067] (i) When the light intensity is controlled within the range of 50% or more and 100% or less

[0068] When the light intensity (target light intensity) is A% (50≤A≤100) through the dimming control process of Example 1, the first half of the intervals (e.g., 16 intervals) of all intervals of a frame (e.g., N=32 intervals) are controlled to emit light at the maximum intensity, and the second half of the intervals (16 intervals) are controlled to emit light at an intensity of (A×2-100)%. That is, the dimming control is performed according to the following light emission profile: before A=50%, the first half of the intervals emit light at the maximum intensity, while the second half of the intervals gradually reduce the intensity, and when A=50%, the intensity is set to 0 (no light emission) (refer to Figure 7B luminous outline 703 to luminous outline 705).

[0069] (ii) When the light intensity is controlled within the range of 25% or more and less than 50%

[0070] When the light amount (target light amount) is set to B% (25≤B<50) through the dimming control processing of Example 1, the first 1 / 4 intervals (8 intervals) of all intervals of a frame (for example, N=32 intervals) are controlled to emit light at the maximum intensity, and the next 1 / 4 intervals (8 intervals) are controlled to emit light at an intensity of (B×4-100)%. In addition, the second half of the intervals (16 intervals) of all intervals (32 intervals) are kept at an intensity of 0 (extinguished state). That is, dimming control is performed using the following light emission profile: before B=25%, the first 1 / 4 interval emits light at the maximum intensity, and the next 1 / 4 interval gradually reduces the intensity, and when B=25%, it is set to an intensity of 0 (no light) (refer to Figure 7B luminous outline 705 to luminous outline 707).

[0071] (iii) Control the light intensity to 100 / 2 n+2 % or more and less than 100 / 2 n+1 % range, when the light intensity (target light intensity) is set to C% by the dimming control process of Example 1 (100 / 2 n+2 ≤C<100 / 2 n+1 ), the first N / 2 of all intervals of a frame (e.g., N=32 intervals) n+2 intervals (for example, when N=32, 4 intervals (when n=1), 2 intervals (when n=2), or 1 interval (when n=3); in addition, in the case of 32 divisions, a maximum of n=3) are used to control the light emission at the maximum intensity, and the next N / 2 intervals are n+2 intervals (when N=32, 4 intervals (when n=1), 2 intervals (when n=2), or 1 interval (when n=3)) with (C×2 n+2 -100)% intensity for light emission control. In addition, the remaining (1-N / 2 n+2 ) intervals (when N=32, 24 intervals (when n=1), 28 intervals (when n=2), or 30 intervals (when n=3)) are maintained at intensity 0 (extinguished state).

[0072] For example, before C=12.5%, the dimming control is performed with the following lighting profile: the first 1 / 8 interval (4 intervals) is lit at maximum intensity, and the intensity is gradually reduced in the next 1 / 8 interval (4 intervals), and when C=12.5%, the intensity is set to 0 (no light) (refer to Figure 7B The remaining 3 / 4 intervals (24 intervals) are kept at an intensity of 0 (off state).

[0073] In addition, until C=6.25%, the dimming control is performed with the following luminous profile: the first 1 / 16 interval (2 intervals) emits light at the maximum intensity, and the intensity is gradually reduced in the next 1 / 16 interval (2 intervals), and the intensity is set to 0 (no light) when C=6.25% (refer to Figure 7B The remaining 7 / 8 intervals (28 intervals) are kept at an intensity of 0 (off state).

[0074] Furthermore, until C=3.125%, the dimming control is performed with the following luminous profile: the first 1 / 32 interval (1 interval) emits light at the maximum intensity, and the intensity is gradually reduced in the next 1 / 32 interval (1 interval), and the intensity is set to 0 (no light) when C=3.125% (refer to Figure 7B The remaining 15 / 16 intervals (30 intervals) are kept at an intensity of 0 (off state).

[0075] <Details of Dimming Control Process 1: Example 1>

[0076] Figure 8 This is a flowchart for explaining the details of the light emitting contour generation process of the dimming control process 1 (Example 1) based on the present embodiment. Here, the action subject of each step of the flowchart is additionally set, or can also be set to the CPU or system controller (control device) of the processor 200. As described above, when the light source device 101 is set inside the endoscope device 100, the action subject is the light source control unit (FPGA) 1016. In the following, the light source control unit 1016 is described as the action subject. However, for example, when the light source device 101 is set on the processor 200 side, the action subject can also be set to other control devices (CPU, etc.) (it can still be set to the light source control unit 1016). In addition, this flowchart is a light emitting contour generation process performed in one frame (current frame), and the light emitting contour generation process is repeated until the target brightness specified by the operator (the target cumulative value described below) is reached. That is, based on the cumulative brightness value generation of the current frame (according to Figure 8 The luminous profile (generated by the flowchart) is used in the dimming control processing of the next frame.

[0077] (i)S801

[0078] The light source control unit 1016 illuminates the subject according to the luminous intensity and luminous time calculated in the previous frame (luminous profile generated in the previous frame), obtains the image signal captured by the camera unit 104 (the signal of one pixel in the current frame), and converts it into brightness data.

[0079] (ii)S802

[0080] The light source control unit 1016 accumulates the brightness data (brightness value of one pixel) of the video signal acquired in S801 .

[0081] (iii)S803

[0082] The light source control unit 1016 determines whether the brightness data of the image signal of the current frame has been obtained. When the brightness data of the current frame has been obtained (when "Yes" in S803), the process goes to S804. When all the brightness data of the current frame has not been obtained (when "No" in S803), the process returns to S801 and continues the process from S801 to S803 until the brightness data of all pixels in the current frame are obtained.

[0083] (iv)S804

[0084] The light source control unit 1016 completes the integration of the brightness data. Thus, the light source control unit 1016 has acquired the brightness integration value of the current frame (for one frame).

[0085] (v)S805

[0086] The light source control unit 1016 determines whether the brightness cumulative value of the current frame acquired in S804 is equal to the target cumulative value. Here, the target cumulative value is a value determined corresponding to the brightness level specified (indicated) by the operator in the UI (user interface) of the endoscope device 100 (for example, a table of target cumulative values ​​corresponding to the brightness levels is pre-designated).

[0087] When the brightness cumulative value acquired in S804 is equal to the target cumulative value (Yes in S805), the process proceeds to S806. When the brightness cumulative value acquired in S804 is different from the target cumulative value (No in S805), the process proceeds to S807.

[0088] (vi)S806

[0089] The light source control unit 1016 maintains the current light amount (the light emission intensity and light emission time of the calculation result of the previous frame: the light emission profile).

[0090] (vii)S807

[0091] The light source control unit 1016 determines whether the brightness cumulative value of the current frame obtained in S804 is greater than the target cumulative value. When the brightness cumulative value obtained in S804 is greater than the target cumulative value (when "yes" in S807), the process goes to S808. When the brightness cumulative value obtained in S804 is less than the target cumulative value (when "no" in S807), the process goes to S809.

[0092] (viii)S808

[0093] The light source control unit 1016 reduces the light amount set in the previous frame at a predetermined ratio (the light amount of the fixed value component may be reduced), and determines the light amount in the next frame (target light amount). The lower limit of the reduction is set to 3.125%.

[0094] (ix)S809

[0095] The light source control unit 1016 increases the light amount set in the previous frame (the light amount to which a fixed value component may be added) by a predetermined ratio and determines the light amount in the next frame (target light amount). The upper limit of the increase is set to 100%.

[0096] (x)S810

[0097] The light source control unit 1016 determines whether the maintained light amount, the light amount obtained after the reduction, or the light amount obtained after the increase (target light amount A) falls within the range of 50% to 100% (or "greater than 50%). When the target light amount A% is within the range of 50% to 100% (when "Yes" in S810: the light amount at this time is set to A%), the process goes to S811. When the target light amount A% is outside the range of 50% to 100% (when "No" in S810), the process goes to S812.

[0098] (xi)S811

[0099] The light source control unit 1016 divides one frame time into N parts to generate the following light-emitting profile: the light is emitted at maximum intensity (100%) in the first (first half) N / 2 intervals (interval 1 to N / 2: when N=32, interval 1 to interval 16) of the interval divided into N parts, and the light is emitted at (target light amount A×2-100)% in the other N / 2 intervals (interval 17 to interval 32).

[0100] (xii)S812

[0101] The light source control unit 1016 determines whether the maintained light amount, the light amount obtained after the reduction, or the light amount obtained after the increase (target light amount B) falls within the range of 25% or more and less than 50% (it can also be "greater than 25%" or "less than 50%"). When the target light amount B is within the range of 25% or more and less than 50% (when "yes" in S812: the light amount at this time is set to B%), the processing goes to S813. When the target light amount B is outside the range of 25% or more and less than 50% (when "no" in S812: less than 25%), the processing goes to S814.

[0102] (xiii)S813

[0103] The light source control unit 1016 generates the following light emission profile: the first N / 4 intervals of the interval divided by N (interval 1 to interval N / 4: when N=32, interval 1 to interval 8) emit light at maximum intensity (100%), the next N / 4 intervals (interval (N / 4)+1 to interval N / 2: when N=32, interval 9 to interval 16) emit light at (target light amount B×4-100)%, and the other N / 2 intervals (interval (N / 2)+1 to interval N: when N=32, interval 17 to interval 32) are set to non-light emission (off state).

[0104] (xiv)S814

[0105] When the target light is less than 25%, it is 100 / 2 n+2 Above and less than 100 / 2 n+1 When (at this time, the target light amount is C%), the following light profile is generated: the first N / 2 of all intervals (for example, N = 32 intervals) of a frame n+2 The interval (interval 1 to interval N / 2 n+2 Until then) emits light at maximum intensity (100%), and in the next N / 2 n+2 Interval (interval N / 2 n+2 +1 to interval N / 2 n+1 (target light intensity C×2 n+2 -100)% intensity, and in other intervals (interval N / 2 n+1 +1 to interval N) is set to intensity 0 (off state).

[0106] Furthermore, when N=32, n=1 to 3, when n=1, it is 12.5% ​​or more and less than 25%, when n=2, it is 6.25% or more and less than 12.5%, and when n=3, it is 3.125% or more and less than 6.25%.

[0107] (xv) As described above, based on the light emission profile generated for the current frame by the light emission profile generation process including S801 to S814, the dimming control process for the next frame is executed (Example 1). If the brightness cumulative value obtained by the dimming control process in the next frame is different from the target cumulative value, further execution is performed. Figure 8 The light emitting outline generation process is repeated until the brightness cumulative value in the current frame is equal to the target cumulative value.

[0108] In addition, according to Example 1, when the target light amount is between 25% and 100% (when the target light amount is A% or B%), the period of light emission at maximum intensity is equivalent to half of the light emission period, and the period of light emission not at maximum intensity must be less than half of the total light emission period (also less than half of the total divided period). For example, if the condition is that the target light amount A is 50% or more and 100%, light is emitted at maximum intensity during half of the total period, and light is emitted at an intensity weaker than the maximum intensity during the remaining period. The reason why the double exposure image is generated is that the difference in area between the maximum intensity period (for example, 16 periods when N=32) and the period other than the maximum intensity is large. Therefore, by making their area ratio less than 1.0, the influence of the double exposure image can be reduced.

[0109] <Overview of Dimming Control Process 2: Embodiment 2>

[0110] Fig.9A and Fig. 9B This is a diagram for explaining the outline of the dimming control process 2 (Example 2) according to the present embodiment.

[0111] exist Fig.9A and Fig. 9B In, with Fig. 7A and Figure 7B Similarly, as an example, a frame period (33.33 ms) of the imaging unit 104 (eg, a CMOS sensor) driven at 30 frames per second (FPS) is divided into 32 (2 5 ) interval to perform dimming control processing. Fig.9A and Fig. 9B In the embodiment, the global exposure period 901 is also equivalent to the blanking period, and is a period for all pixels to accumulate effective charges in the next reading operation, and is set to 1.2ms, for example. After 1.2ms from the start of one frame period, the remaining 32.13ms are used to perform the rolling shutter reading operation of the effective pixels (rolling shutter period 902). Depending on how the dimming control process is performed during the rolling shutter period 902, scanning line noise or double exposure images may be generated.

[0112] As described above, in the dimming control process of this embodiment, light quantity control (increase or decrease) is performed based on the comparison result of the brightness cumulative value of the current image (captured image) and the target cumulative value determined (instructed) by the operator. However, even when light quantity control is required, a sudden change in light quantity (brightness) will become stressful for the operator, so the light quantity is gradually increased or decreased (for example, by 5% each time) to control so as not to cause a sudden brightness change.

[0113] (i) When the light intensity is controlled within the range of 50% or more and 100% or less

[0114] When the light intensity (target light intensity) is set to A% (50≤A≤100) by the dimming control process of Example 2, the light emission control is performed at an intensity of A% in all intervals of a frame (for example, N=32 intervals), and there is no interval where the light is not emitted (extinguished). That is, the dimming control is performed with the following light emission profile: the intensity is gradually reduced in all intervals from interval 1 to interval N (N=32) until A=50%, and when A=50%, the intensity is halved in all intervals (refer to Fig. 9B luminous outline 903 to luminous outline 705).

[0115] (ii) When the light intensity is controlled within the range of 25% or more and less than 50%

[0116] When the light quantity (target light quantity) is set to B% (25≤B<50) by the dimming control process of Example 2, the first 1 / 4 intervals (8 intervals) of all intervals in a frame (for example, N=32 intervals) are controlled to emit light at an intensity of (150-B×2)%, and the remaining 3 / 4 intervals (24 intervals) are controlled to emit light at an intensity of (B-25)×2%. That is, the dimming control is performed with the following light emission profile: before reaching B=25%, the intensity of the first 1 / 4 intervals gradually increases from 50%, and is set to the maximum intensity (100%) when B=25%, and the intensity of the remaining 3 / 4 intervals (24 intervals) gradually decreases from 50%, and is set to an intensity of 0 (no light emission) when B=25% (refer to Fig. 9B luminous outline 905 to luminous outline 907).

[0117] (iii) Control the light intensity to 100 / 2 n+2 % or more and less than 100 / 2 n+1 % range: The dimming control process less than 25% is the same as that in Example 1

[0118] When the light intensity (target light intensity) is set to C% by the dimming control process of Example 2 (100 / 2 n+2 ≤C<100 / 2 n+1 ), the first N / 2 of all intervals of a frame (e.g., N=32 intervals) n+2 intervals (for example, when N=32, 4 intervals (when n=1), 2 intervals (when n=2), or 1 interval (when n=3); in addition, in the case of 32 divisions, a maximum of n=3) are used to control the light emission at the maximum intensity, and the next N / 2 intervals are n+2 intervals (when N=32, 4 intervals (when n=1), 2 intervals (when n=2), or 1 interval (when n=3)) with (C×2 n+2 -100)% intensity for light emission control. In addition, the remaining (1-N / 2n+2 ) intervals (when N=32, 24 intervals (when n=1), 28 intervals (when n=2), or 30 intervals (when n=3)) are maintained at intensity 0 (extinguished state).

[0119] For example, before C=12.5%, the dimming control is performed with the following lighting profile: the first 1 / 8 interval (4 intervals) is lit at maximum intensity, and the intensity is gradually reduced in the next 1 / 8 interval (4 intervals), and when C=12.5%, the intensity is set to 0 (no light) (refer to Fig. 9B The remaining 3 / 4 intervals (24 intervals) are kept at an intensity of 0 (off state).

[0120] In addition, until C=6.25%, the dimming control is performed with the following luminous profile: the first 1 / 16 interval (2 intervals) emits light at the maximum intensity, and the intensity is gradually reduced in the next 1 / 16 interval (2 intervals), and the intensity is set to 0 (no light) when C=6.25% (refer to Fig. 9B The remaining 7 / 8 intervals (28 intervals) are kept at an intensity of 0 (off state).

[0121] Furthermore, until C=3.125%, the dimming control is performed with the following luminous profile: the first 1 / 32 interval (1 interval) emits light at the maximum intensity, and the intensity is gradually reduced in the next 1 / 32 interval (1 interval), and the intensity is set to 0 (no light) when C=3.125% (refer to Fig. 9B The remaining 15 / 16 intervals (30 intervals) are kept at an intensity of 0 (off state).

[0122] <Details of Dimming Control Process 2: Example 2>

[0123] Fig.10This is a flowchart for explaining the details of the light emitting contour generation process of the dimming control process 1 (Example 2) based on the present embodiment. Here, the action subject of each step of the flowchart is additionally set, or can also be set to the CPU or system controller (control device) of the processor 200. As described above, when the light source device 101 is set inside the endoscope device 100, the action subject is the light source control unit (FPGA) 1016. In the following, the light source control unit 1016 is described as the action subject. However, for example, when the light source device 101 is set on the processor 200 side, the action subject can also be set to other control devices (such as CPU) (it can still be set to the light source control unit 1016). In addition, this flowchart is a light emitting contour generation process performed in one frame (current frame), and the light emitting contour generation process is repeated until the target brightness specified by the operator (the target cumulative value described below) is reached. That is, based on the cumulative brightness value generation of the current frame (according to Fig.10 The luminous profile (generated by the flowchart) is used in the dimming control processing of the next frame.

[0124] (i)S1001

[0125] The light source control unit 1016 illuminates the subject according to the luminous intensity and luminous time calculated in the previous frame (luminous profile generated in the previous frame), obtains the image signal captured by the camera unit 104 (the signal of one pixel in the current frame), and converts it into brightness data.

[0126] (ii)S1002

[0127] The light source control unit 1016 accumulates the brightness data (brightness value of one pixel) of the video signal acquired in S1001 .

[0128] (iii)S1003

[0129] The light source control unit 1016 determines whether the brightness data of the image signal of the current frame has been obtained. When the brightness data of the current frame has been obtained (when "yes" in S1003), the process goes to S1004. When all the brightness data of the current frame has not been obtained (when "no" in S1003), the process returns to S1001, and the processes from S1001 to S1003 are continued until the brightness data of all pixels in the current frame are obtained.

[0130] (iv)S1004

[0131] The light source control unit 1016 completes the integration of the brightness data. Thus, the light source control unit 1016 has acquired the brightness integration value of the current frame (for one frame).

[0132] (v)S1005

[0133] The light source control unit 1016 determines whether the brightness cumulative value of the current frame acquired in S1004 is equal to the target cumulative value. Here, the target cumulative value is a value determined corresponding to the brightness level specified (indicated) by the operator in the UI (user interface) of the endoscope device 100 (for example, a table of target cumulative values ​​corresponding to the brightness levels is pre-designated).

[0134] When the brightness cumulative value acquired in S1004 is equal to the target cumulative value (YES in S1005), the process proceeds to S1006. When the brightness cumulative value acquired in S1004 is different from the target cumulative value (NO in S1005), the process proceeds to S1007.

[0135] (vi)S1006

[0136] The light source control unit 1016 maintains the current light amount (the light emission intensity and light emission time of the calculation result of the previous frame: the light emission profile).

[0137] (vii)S1007

[0138] The light source control unit 1016 determines whether the brightness cumulative value of the current frame obtained in S1004 is greater than the target cumulative value. When the brightness cumulative value obtained in S1004 is greater than the target cumulative value (when "yes" in S1007), the process goes to S1008. When the brightness cumulative value obtained in S1004 is less than the target cumulative value (when "no" in S1007), the process goes to S1009.

[0139] (viii)S1008

[0140] The light source control unit 1016 reduces the light amount set in the previous frame at a predetermined ratio (the light amount of the fixed value component may be reduced), and determines the light amount in the next frame (target light amount). The lower limit of the reduction is set to 3.125%.

[0141] (ix)S1009

[0142] The light source control unit 1016 increases the light amount set in the previous frame (the light amount to which a fixed value component may be added) by a predetermined ratio and determines the light amount in the next frame (target light amount). The upper limit of the increase is set to 100%.

[0143] (x)S1010

[0144] The light source control unit 1016 determines whether the maintained light amount, the light amount obtained after the reduction, or the light amount obtained after the increase (target light amount) falls within the range of 50% to 100% (or "greater than 50%). When the target light amount is within the range of 50% to 100% (when "yes" in S1010: the light amount at this time is set to A%), the process goes to S1011. When the target light amount is outside the range of 50% to 100% (when "no" in S1010), the process goes to S1012.

[0145] (xi)S1011

[0146] The light source control unit 1016 divides one frame time into N parts, and generates a light emission profile in which light is emitted at an intensity of A% of the target light amount in all the N divided sections (sections 1 to 32 when N=32).

[0147] (xii)S1012

[0148] The light source control unit 1016 determines whether the maintained light amount, the light amount obtained after the reduction, or the light amount obtained after the increase (target light amount) falls within the range of 25% or more and less than 50% (it can also be "greater than 25%" or "less than 50%"). When the target light amount is within the range of 25% or more and less than 50% (when "yes" in S1012: the light amount at this time is set to B%), the processing goes to S1013. When the target light amount is outside the range of 25% or more and less than 50% (when "no" in S1012: less than 25%), the processing goes to S1014.

[0149] (xiii)S1013

[0150] The light source control unit 1016 generates the following light emission profile: in the first N / 4 intervals of the interval divided by N (interval 1 to interval N / 4: when N=32, interval 1 to interval 8), light is emitted with an intensity of (150-target light amount B×2)%, and in the remaining 3×(N / 4) intervals (interval (N / 4)+1 to interval N: when N=32, intervals 9 to 32), light is emitted with an intensity of (target light amount B-25)×2%.

[0151] (xiv)S1014

[0152] When the target light is less than 25%, it is 100 / 2 n+2 Above and less than 100 / 2 n+1 When (at this time, the target light amount C%) is set, the following light profile is generated: the first N / 2 of all intervals (for example, N = 32 intervals) of a frame n+2 The interval (interval 1 to interval N / 2 n+2Until then) emits light at maximum intensity (100%), and in the next N / 2 n+2 Interval (interval N / 2 n+2 +1 to interval N / 2 n+1 (target light intensity C×2 n+2 -100)% intensity, and in other intervals (interval N / 2 n+1 +1 to interval N) is set to intensity 0 (off state).

[0153] Furthermore, when N=32, n=1 to 3, when n=1, it is 12.5% ​​or more and less than 25%, when n=2, it is 6.25% or more and less than 12.5%, and when n=3, it is 3.125% or more and less than 6.25%.

[0154] (xv) As described above, based on the light emission profile generated for the current frame by the light emission profile generation process including S1001 to S1014, the dimming control process for the next frame is executed (Example 2). If the brightness cumulative value obtained by the dimming control process in the next frame is different from the target cumulative value, further execution is performed. Fig.10 The light emitting outline generation process is repeated until the brightness cumulative value in the current frame is equal to the target cumulative value.

[0155] In addition, according to Example 2, when the target light amount is between 25% and 50% (at the target light amount B%), the area during the period of light emission at (150-target light amount B×2)% is sometimes smaller than the area during the period of light emission at (target light amount B-25)×2%. That is, sometimes the ratio of area=period×intensity is greater than 1.0, but the difference in the intensities of the two in this case is small. Therefore, (due to the situation where light emission is continuously emitted at approximately the same intensity), the influence (difficulty in viewing the image) caused by the generation of a double exposure image is very small.

[0156] Furthermore, in the case of Example 2, under the condition of the target light amount A (when 50%≤A≤100%), a contour is formed that emits continuous light, thereby reducing the discomfort caused to the operator or patient by the flickering of the emitted light when the endoscope device is outside the body cavity.

[0157] <Effects of Implementation Methods>

[0158] According to this embodiment, rolling shutter distortion and artifacts can be avoided while ensuring sufficient light quantity to capture the subject. In addition, since the continuous pulse light emission period does not change during the rolling shutter period, the vertical movement of the horizontal stripes can be made less noticeable.

[0159] Furthermore, by dividing a frame into two m(m is an integer greater than or equal to 2) dimming intervals, the calculation required for generating the light profile is set to only division that can be realized by displacement, and the resource saving of the light source device can be realized only by the light source control unit (FPGA) without using a CPU or other computing elements. Therefore, the light source device can be installed on the side of the endoscope device in a closed space with limited computing resources.

[0160] <Specific Matters of the Present Disclosure>

[0161] (1) Specific matters 1

[0162] A light source device generates illumination light for irradiating a subject, and comprises:

[0163] a semiconductor light emitting element that emits light; and

[0164] A light source control unit, which generates a light emission profile of the semiconductor light emitting element and drives the semiconductor light emitting element based on the light emission profile;

[0165] The light source control unit performs the following processing:

[0166] One frame period of the image signal acquired by the imaging element is divided into N periods (N=2 m m is an integer greater than 2) dimming interval;

[0167] During the one frame, a 2-bit image is generated according to the target light amount. k A light emitting profile for controlling the light emitting intensity of each unit of the dimming interval (k=an integer from 0 to m); and

[0168] Based on the light emitting profile, dimming control of the next frame is performed.

[0169] (2) Specific matters 2

[0170] The light source device according to specific item 1, wherein

[0171] The light source control unit divides the one frame period so that one dimming interval is smaller than a global exposure period.

[0172] (3) Specific matters 3

[0173] The light source device according to specific item 1, wherein

[0174] The light source control unit determines the target light amount by comparing a brightness integrated value of an image signal of a current frame acquired using a light emission profile of a previous frame with an input target brightness integrated value.

[0175] (4) Specific matters 4

[0176] The light source device according to specific item 3, wherein

[0177] When the luminance integrated value of the current frame is different from the target luminance integrated value, the light source control unit performs dimming control so that the light amount is gradually increased or decreased by a predetermined amount or a predetermined ratio to reach the target luminance integrated value.

[0178] (5) Specific matters 5

[0179] The light source device according to specific item 1, wherein

[0180] When the target light amount is in the range of more than 50% and less than 100%, the light source control unit generates the following light emission profile, that is, the light is emitted with maximum intensity in the dimming interval 1 to the dimming interval N / 2, and the light is emitted with an intensity of (target light amount × 2-100)% in the dimming interval (N / 2)+1 to the dimming interval N.

[0181] (6) Specific matters 6

[0182] The light source device according to specific item 5, wherein

[0183] When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, i.e., emitting light with maximum intensity in dimming interval 1 to dimming interval N / 4, emitting light with an intensity of (target light amount × 4-100)% in dimming interval (N / 4)+1 to dimming interval N / 2, and being extinguished in the remaining dimming interval.

[0184] (7) Specific matters 7

[0185] The light source device according to specific item 6, wherein

[0186] When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 % (n=integer from 1 to m-2), the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

[0187] (8) Specific matters 8

[0188] The light source device according to specific item 1, wherein

[0189] When the target light amount is in a range of 50% to 100%, the light source control unit generates the light emission profile such that light is emitted at the intensity of the target light amount in dimming intervals 1 to N.

[0190] (9) Specific matters 9

[0191] The light source device according to specific item 8, wherein

[0192] When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, that is, the light is emitted with an intensity of (150-target light amount×2)% in the dimming interval 1 to the dimming interval N / 4, and the light is emitted with an intensity of (target light amount-25)×2% in the dimming interval (N / 4)+1 to the dimming interval N.

[0193] (10) Specific matters 10

[0194] The light source device according to specific item 9, wherein

[0195] When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 % (n=integer from 1 to m-2), the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

[0196] (11) Specific matters 11

[0197] An endoscope system inserts an endoscope device into an observation object to obtain an image of the object, and comprises:

[0198] Light source device;

[0199] an imaging element that irradiates the subject with illumination light emitted from the light source device and detects reflected light from the subject to generate an image signal; and

[0200] A processor, which processes the image signal to generate an image of the subject and displays it on a monitor;

[0201] The light source device comprises:

[0202] a semiconductor light emitting element that emits light; and

[0203] A light source control unit, which generates a light emission profile of the semiconductor light emitting element and drives the semiconductor light emitting element based on the light emission profile;

[0204] The light source control unit performs the following processing:

[0205] One frame period of the image signal acquired by the imaging element is divided into N periods (N=2 m m is an integer greater than 2) dimming interval;

[0206] During the one frame, a 2-bit image is generated according to the target light amount. k A light emitting profile for controlling the light emitting intensity of each unit of the dimming interval (k=an integer from 0 to m); and

[0207] Based on the light emitting profile, dimming control of the next frame is performed.

[0208] (12) Specific matters 12

[0209] The endoscope system according to specific item 11, wherein

[0210] The light source control unit divides the one frame period so that one dimming interval is smaller than a global exposure period.

[0211] (13) Specific matters 13

[0212] The endoscope system according to specific item 11, wherein

[0213] The light source control unit determines the target light amount by comparing a brightness integrated value of an image signal of a current frame acquired using a light emission profile of a previous frame with an input target brightness integrated value.

[0214] (14) Specific matters 14

[0215] An endoscope system according to specific item 13, wherein:

[0216] When the luminance integrated value of the current frame is different from the target luminance integrated value, the light source control unit performs dimming control so that the light amount is gradually increased or decreased by a predetermined amount or a predetermined ratio to reach the target luminance integrated value.

[0217] (15) Specific matters 15

[0218] The endoscope system according to specific item 11, wherein

[0219] When the target light amount is in the range of more than 50% and less than 100%, the light source control unit generates the following light emission profile, that is, the light is emitted with maximum intensity in the dimming interval 1 to the dimming interval N / 2, and the light is emitted with an intensity of (target light amount × 2-100)% in the dimming interval (N / 2)+1 to the dimming interval N.

[0220] (16) Specific matters 16

[0221] An endoscope system according to specific item 15, wherein:

[0222] When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, i.e., emitting light with maximum intensity in dimming interval 1 to dimming interval N / 4, emitting light with an intensity of (target light amount × 4-100)% in dimming interval (N / 4)+1 to dimming interval N / 2, and being extinguished in the remaining dimming interval.

[0223] (17) Specific matters 17

[0224] The endoscope system according to specific item 16, wherein:

[0225] When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 % (n=integer from 1 to m-2), the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

[0226] (18) Specific matters 18

[0227] The endoscope system according to specific item 11, wherein

[0228] When the target light amount is in a range of 50% to 100%, the light source control unit generates the light emission profile such that light is emitted at the intensity of the target light amount in dimming intervals 1 to N.

[0229] (19) Specific matters 19

[0230] An endoscope system according to specific item 18, wherein:

[0231] When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, that is, the light is emitted with an intensity of (150-target light amount×2)% in the dimming interval 1 to the dimming interval N / 4, and the light is emitted with an intensity of (target light amount-25)×2% in the dimming interval (N / 4)+1 to the dimming interval N.

[0232] (20) Specific matters 20

[0233] An endoscope system according to specific item 19, wherein:

[0234] When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 % (n=integer from 1 to m-2), the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

[0235] (21) Specific matters 21

[0236] The endoscope system according to specific item 11, wherein

[0237] The light source device is disposed inside the endoscope device.

[0238] Description of Reference Numerals

[0239] 1 Endoscope system; 100 Endoscope device; 104 Camera unit; 200 Processor; 101 Light source device; 1011 Green LED; 1012 Blue LED; 1013 Red LED; 1014 Amber LED; 1015 UVLED; 1016 Light source control unit; 1017, 1018 Orthogonal prisms; 201 System controller; 202 Light measuring unit; 300 Monitor.

Claims

1. A light source device for generating illumination light to illuminate a subject, the light source device comprising: A semiconductor light emitting element that emits light; as well as A light source control unit, which generates a light emission profile of the semiconductor light emitting element and drives the semiconductor light emitting element based on the light emission profile; The light source control unit performs the following processing: A frame period of the image signal acquired by the imaging element is divided into N dimming intervals, where: N=2 m An integer of, m is an integer greater than 2; During the one frame, a 2-bit k The light profile of the light intensity is controlled by the units of the dimming interval, wherein k=an integer from 0 to m; as well as Based on the light emitting profile, dimming control of the next frame is performed.

2. The light source device according to claim 1, wherein: The light source control unit divides the one frame period so that one dimming interval is smaller than a global exposure period.

3. The light source device according to claim 1, wherein: The light source control unit determines the target light amount by comparing a brightness integrated value of an image signal of a current frame acquired using a light emission profile of a previous frame with an input target brightness integrated value.

4. The light source device according to claim 3, wherein: When the luminance integrated value of the current frame is different from the target luminance integrated value, the light source control unit performs dimming control so that the light amount is gradually increased or decreased by a predetermined amount or a predetermined ratio to reach the target luminance integrated value.

5. The light source device according to claim 1, wherein: When the target light amount is in the range of more than 50% and less than 100%, the light source control unit generates the following light emission profile, that is, the light is emitted with maximum intensity in the dimming interval 1 to the dimming interval N / 2, and the light is emitted with an intensity of (target light amount × 2-100)% in the dimming interval (N / 2)+1 to the dimming interval N.

6. The light source device according to claim 5, wherein: When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, i.e., emitting light with maximum intensity in dimming interval 1 to dimming interval N / 4, emitting light with an intensity of (target light amount × 4-100)% in dimming interval (N / 4)+1 to dimming interval N / 2, and being extinguished in the remaining dimming interval.

7. The light source device according to claim 6, wherein: When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 %, wherein n=an integer from 1 to m-2, the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

8. The light source device according to claim 1, wherein: When the target light amount is in a range of 50% to 100%, the light source control unit generates the light emission profile such that light is emitted at the intensity of the target light amount in dimming intervals 1 to N.

9. The light source device according to claim 8, wherein: When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, that is, the light is emitted with an intensity of (150-target light amount×2)% in the dimming interval 1 to the dimming interval N / 4, and the light is emitted with an intensity of (target light amount-25)×2% in the dimming interval (N / 4)+1 to the dimming interval N.

10. The light source device according to claim 9, wherein: When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 %, wherein n=an integer from 1 to m-2, the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

11. An endoscope system for inserting an endoscope device into an observation object and acquiring an image of the object, the endoscope system comprising: Light source device; an imaging element that irradiates the subject with illumination light emitted from the light source device and detects reflected light from the subject to generate an image signal; and A processor, which processes the image signal to generate an image of the subject and displays it on a monitor; The light source device comprises: A semiconductor light emitting element that emits light; as well as A light source control unit, which generates a light emission profile of the semiconductor light emitting element and drives the semiconductor light emitting element based on the light emission profile; The light source control unit performs the following processing: A frame period of the image signal acquired by the imaging element is divided into N dimming intervals, wherein: N=2 m An integer of, m is an integer greater than 2; During the one frame, a 2-bit k The light profile of the light intensity is controlled by the units of the dimming interval, wherein k=an integer from 0 to m; as well as Based on the light emitting profile, dimming control of the next frame is performed.

12. The endoscope system according to claim 11, wherein: The light source control unit divides the one frame period so that one dimming interval is smaller than a global exposure period.

13. The endoscope system according to claim 11, wherein: The light source control unit determines the target light amount by comparing a brightness integrated value of an image signal of a current frame acquired using a light emission profile of a previous frame with an input target brightness integrated value.

14. The endoscope system according to claim 13, wherein: When the luminance integrated value of the current frame is different from the target luminance integrated value, the light source control unit performs dimming control so that the light amount is gradually increased or decreased by a predetermined amount or a predetermined ratio to reach the target luminance integrated value.

15. The endoscope system according to claim 11, wherein: When the target light amount is in the range of more than 50% and less than 100%, the light source control unit generates the following light emission profile, that is, the light is emitted with maximum intensity in the dimming interval 1 to the dimming interval N / 2, and the light is emitted with an intensity of (target light amount × 2-100)% in the dimming interval (N / 2)+1 to the dimming interval N.

16. The endoscope system according to claim 15, wherein: When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, i.e., emitting light with maximum intensity in dimming interval 1 to dimming interval N / 4, emitting light with an intensity of (target light amount × 4-100)% in dimming interval (N / 4)+1 to dimming interval N / 2, and being extinguished in the remaining dimming interval.

17. The endoscope system according to claim 16, wherein: When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 %, wherein n=an integer from 1 to m-2, the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

18. The endoscope system according to claim 11, wherein: When the target light amount is in a range of 50% to 100%, the light source control unit generates the light emission profile such that light is emitted at the intensity of the target light amount in dimming intervals 1 to N.

19. The endoscope system according to claim 18, wherein: When the target light amount is in the range of greater than 25% and less than 50%, the light source control unit generates the following light emission profile, that is, the light is emitted with an intensity of (150-target light amount×2)% in the dimming interval 1 to the dimming interval N / 4, and the light is emitted with an intensity of (target light amount-25)×2% in the dimming interval (N / 4)+1 to the dimming interval N.

20. The endoscope system according to claim 19, wherein: When the target light intensity is 100 / 2 n+2 % or more and less than 100 / 2 n+1 %, wherein n=an integer from 1 to m-2, the light source control unit generates the following light emission profile, that is, in the dimming interval 1 to the dimming interval N / 2 n+2 At maximum intensity, in the dimming range (N / 2 n+2 )+1 to dimming interval N / 2 n+1 (target light intensity × 2 n+2 -100)% intensity and is off in the remaining dimming range.

21. The endoscope system according to claim 11, wherein: The light source device is disposed inside the endoscope device.

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