Light source device and endoscope system

Abstract

The present disclosure proposes a light source device that is capable of avoiding the occurrence of distortion or artifacts due to a rolling shutter of an image pickup element, while being capable of quickly responding to changes occurring during a rolling shutter period (pixel reading period) and performing light quantity control, and that generates illumination light that illuminates a subject, the light source device including: a plurality of semiconductor light emitting elements for emitting light of different wavelength bands; and a control section for controlling light emission profiles of the plurality of semiconductor light emitting elements and driving the plurality of semiconductor light emitting elements, wherein the control section controls the light emission profiles of the plurality of semiconductor light emitting elements so as to perform main light emission during a pseudo-global exposure period of the image pickup element and perform preparatory light emission during at least a part of a pixel reading period of the image pickup element, and the light emission level of the preparatory light emission is lower than the light emission level of the main light emission.

Description

Technical Field

[0001] This disclosure relates to a light source device and an endoscope system. Background Technology

[0002] In a conventional endoscope device equipped with an image sensor using a rolling shutter method, simulated global exposure is performed by turning off the light source during the effective pixel readout period of the image sensor (during the rolling shutter period) and turning on the light source at other times (during the simulated global exposure period) (pulse emission control), thus avoiding unwanted phenomena caused by the rolling shutter, such as distortion or artifacts.

[0003] On the other hand, when the light source is completely extinguished during the rolling shutter, the amount of light will be insufficient depending on the subject (the part of the object being observed), making it impossible to obtain a good image. For example, patent documents 1 to 3 show light source control that includes a portion of the rolling shutter period in the pulsed emission period in order to eliminate this insufficient light.

[0004] Existing technical documents

[0005] Patent documents

[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] The problem that the invention aims to solve

[0010] However, when the light source control is implemented as described in Patent Documents 1 to 3, uneven brightness or horizontal stripes may occur in adjacent frames due to the exposure time difference between each line. Furthermore, due to variations in the pulse emission period of each frame, these uneven brightness or horizontal stripes shift up and down on the displayed screen, becoming glaring. Additionally, when offset emission is performed during rolling shutter speed to eliminate insufficient light, if the offset emission becomes stronger to some extent, unnatural images (artifacts or scan line noise (distortion)) may occur, resulting in a double exposure of a long-exposure image and a high-speed exposure image.

[0011] Furthermore, in the technologies described in Patent Documents 1 to 3, the phenomenon of changes occurring during the light-off period (during the rolling shutter) is not observed during the reading process during this period, but can only be observed in the next reading frame after the next pulse of light exposure. Therefore, there is a risk of perforation or image halo when the tip of the endoscope suddenly approaches the subject. To suppress this risk of perforation or halo, it is necessary to quickly capture the change in image brightness caused by sudden approach and immediately reflect it in the light volume control.

[0012] This disclosure was made in view of this situation, and its purpose is to provide a technique that can avoid distortion or artifacts caused by the rolling shutter of the imaging element, while rapidly responding to changes that occur during the rolling shutter (pixel readout period) and performing light control.

[0013] [Solutions for solving the problem]

[0014] To address the aforementioned issues, this embodiment proposes a light source device for generating illumination light to illuminate a subject. The device comprises: a plurality of semiconductor light-emitting elements that emit light of different wavelengths; and a control unit for controlling the emission profiles of the plurality of semiconductor light-emitting elements and driving the plurality of semiconductor light-emitting elements. The control unit controls the emission profiles of the plurality of semiconductor light-emitting elements to perform main emission during pseudo-global exposure of the imaging element and to perform pre-emission emission during at least a portion of pixel readout of the imaging element, wherein the emission level of the pre-emission emission is lower than the emission level of the main emission emission.

[0015] Furthermore, this embodiment proposes an endoscope system for inserting an endoscope into an object of observation and acquiring an image of the object. The system comprises: a plurality of semiconductor light-emitting elements for emitting light of different wavelengths; an imaging element for illuminating the object with illumination light and detecting reflected light from the object to generate an image signal; a processor for processing the image signal to generate an image of the object and displaying it on a monitor; a main control unit for generating control signals based on the image signals to control the light emission profiles of the plurality of semiconductor light-emitting elements; and a light source control unit for receiving the control signals from the main control unit and driving the plurality of semiconductor light-emitting elements with drive signals corresponding to the light emission profiles. The main control unit controls the light emission profiles of the plurality of semiconductor light-emitting elements to perform main emission during pseudo-global exposure of the imaging element and pre-emission during at least a portion of pixel readout of the imaging element, wherein the emission level of the pre-emission is lower than the emission level of the main emission.

[0016] Further features relating to this disclosure will become apparent from the description and accompanying drawings. Furthermore, this disclosure will be realized and obtained by means of elements and combinations thereof, as well as embodiments described below and in the appended claims.

[0017] It should be understood that the description in this specification is merely exemplary and is not intended to limit the claims or embodiments in any way.

[0018] [Invention Effects]

[0019] According to this disclosure, it is possible to avoid distortion or artifacts caused by the rolling shutter of the imaging element, while rapidly responding to changes that occur during the rolling shutter (pixel readout period) and performing light control. [Image Description]

[0020] Figure 1 This is an example diagram showing the overall appearance of the endoscope system according to this embodiment.

[0021] Figure 2 This is a schematic diagram illustrating the internal structure of the endoscope system according to this embodiment.

[0022] Figure 3 This is a diagram showing an example of the internal configuration of the light source device 201 disposed inside the processor 200.

[0023] Figure 4 This is a graph showing the spectral (wavelength characteristics) of each LED from 2011 to 2015. Figure 5 This is a diagram showing the characteristics of the illumination light (light used to illuminate the observation area) generated by passing each LED through orthogonal prisms 2017 and 2018.

[0024] Figure 6 This is a diagram showing an example of the configuration of a light source using LEDs with different light distributions.

[0025] Figure 7 It is a graph showing the ratio of emitted light to current for each LED.

[0026] Figure 8 This is a diagram showing the effective pixel area and ineffective area of ​​a camera element using a rolling shutter mode, with a CMOS sensor as an example.

[0027] Figure 9 This is a diagram illustrating a typical dimming control process (example) and the observed images acquired in each frame (example).

[0028] Figure 10 This is a diagram illustrating the dimming control process of Control Example 1 of this embodiment (example) and the observation images acquired in each frame (example).

[0029] Figure 11 This is a diagram illustrating the dimming control process of Control Example 2 of this embodiment (example) and the observation images acquired in each frame (example).

[0030] Figure 12 This is a diagram illustrating the dimming control process of Control Example 3 of this embodiment (example) and the observation images acquired in each frame (example).

[0031] Figure 13 This is a diagram illustrating the dimming control process of Control Example 4 of this embodiment (example) and the observation images acquired in each frame (example).

[0032] Figure 14 This is a flowchart illustrating the dimming control process of Control Example 1 and Control Example 2 in this embodiment.

[0033] Figure 15 This is a flowchart illustrating the dimming control process of Control Example 3 and Control Example 4 in this embodiment. [Detailed Implementation]

[0034] The embodiments of this disclosure will now be described with reference to the accompanying drawings. Furthermore, as one embodiment of this disclosure, an endoscope system will be used as an example for description.

[0035] Examples of sites that can be observed using an endoscope include respiratory organs and digestive organs. Examples of respiratory organs include the lungs, bronchi, and ears, nose, and throat. Examples of digestive organs include the large intestine, small intestine, stomach, esophagus, duodenum, uterus, and bladder. When observing these sites, using images that emphasize specific biological structures is more effective.

[0036] Composition of an Endoscopic System

[0037] Figure 1 This is an example diagram showing the overall appearance of the endoscope system according to this embodiment. Figure 2 This is a schematic example diagram showing the internal structure of the endoscope system according to this embodiment. The endoscope system 1 includes an endoscope device (electronic observer) 100, a processor 200, and a monitor 300. The processor side end of the endoscope device 100 is provided with an endoscope connector (hereinafter referred to as "connector") 400, which includes connector circuitry related to the features of this embodiment.

[0038] The endoscope device 100 includes an elongated tubular insertion portion 11 that is inserted into the body of the patient. For example, the endoscope device 100 includes an LCB (Light Carrying Bundle) 101 for guiding illumination light from the light source device 201 described later; a light distribution lens 102 disposed at the exit end of the LCB 101; an imaging unit 103 that receives reflected light from the irradiated portion (observation area) through an objective lens (not shown); a drive signal processing circuit 105 for driving the imaging unit 103; and a first memory 106.

[0039] Irradiation light from the light source device 201 enters the LCB 101 and propagates through repeated total internal reflection within the LCB 101. The illumination light (light source) propagating within the LCB 101 exits from the exit end of the LCB 101, which is located in the front end portion 12 of the insertion portion 11, and illuminates the observation area via the light distribution lens 102. The return light from the illuminated portion passes through the objective lens and is projected onto the pixels on the light-receiving surface of the imaging unit 103 to form an optical image.

[0040] The imaging unit 103 is disposed within the front end portion 12 of the insertion portion 11, and can be a CMOS (Complementary Metal Oxide Semiconductor) image sensor that is a rolling shutter type image sensor. The imaging unit 103 accumulates the optical image (return light from living tissue) formed by each pixel of the light-receiving surface into a charge corresponding to the amount of light, and generates and outputs R, G, B image signals. In addition, the imaging unit 103 is not limited to a CMOS image sensor, and can be any image sensor based on the rolling shutter type, and can also be replaced with other types of imaging devices. The signals output from the imaging unit 103 are processed by the lens connector circuit 401 provided in the lens connector 400, as described below.

[0041] The processor 200 is an integrated device comprising a signal processing unit for processing signals from the endoscope device 100, and a light source device for illuminating the interior of a body cavity that is inaccessible to natural light via the endoscope device 100. In other embodiments, the signal processing unit and the light source device may be configured separately. The processor 200 includes a light source device 201, a system controller 202, a photometer 203, a pre-processing signal circuit 205, a color conversion circuit 206, a post-processing signal circuit 207, and a second memory 208.

[0042] The processor 200 may also have an operation panel (not shown). The operation panel can take various forms. Specifically, it can be, for example, hardware keys for each function packaged on the front of the processor 200, a touchpad-style GUI (graphical user interface), or a combination of hardware keys and a GUI. The operator (physician) can perform the mode switching operations described later through the operation panel.

[0043] The metering unit 203 obtains the brightness information of the image signal obtained by shooting from the gain circuit included in the color conversion circuit 206, compares it with a predetermined appropriate brightness value (for example, the information of the appropriate brightness value can be stored in advance in the internal memory of the metering unit 203, not shown), and notifies the system controller 202 of the comparison result (whether the current brightness value is appropriate, high or low).

[0044] The system controller 202 executes various programs stored in a memory (not shown) and centrally controls the entire endoscope system 1. The system controller 202 uses control signals to control the operation and timing of various circuits in the processor 200 to properly process the endoscope device 100 connected to the processor 200. Additionally, the system controller 202 can be connected to the aforementioned operation panel.

[0045] In addition, the system controller 202 receives a comparison result from the metering unit 203 after comparing it with an appropriate brightness value, determines whether the current exposure should be maintained, whether the exposure should be increased (including the increased level value), or whether the exposure should be decreased (including the decreased level value), and outputs it to the light source device 201 as an exposure control signal.

[0046] Furthermore, the system controller 202 modifies various actions of the endoscope system 1 and the parameters for each action based on instructions from the operator input from the operation panel. For example, when the operator selects an observation mode (mode switching operation) via the operation panel, the system controller 202 outputs a mode selection signal to the light source device 201, which is used to cause the light source corresponding to the observation mode to emit light. As described later, the light source device 201 can, for example, use multiple LEDs (Light Emitting Diodes) that emit light of different wavelengths (see [reference]). Figure 3 When an operator selects an observation mode (e.g., normal observation mode, special light observation mode, SatO2 mode, etc.) by operating a mode selection switch set on the processor 200, the system controller 202 generates a mode selection signal corresponding to the selected mode and provides it to the light source control unit 2016 of the light source device 201 (see reference). Figure 3The light source control unit 2016 determines the combination of light-emitting LEDs, their intensity, and light quantity based on the mode selection signal (for example, pre-stores the combination of light-emitting LEDs corresponding to the mode selection signal in an internal memory not shown), and outputs the necessary LED control signals from each LED 2011 to 2015. When each LED 2011 to 2015 emits light of a different wavelength according to the LED control signals provided from the light source control unit 2016, the emitted light is combined by orthogonal prisms to generate illumination light (composite light).

[0047] Data communication between the endoscope device 100 and the processor 200 can be achieved using wired communication or optical wireless communication.

[0048] like Figure 2 As shown, the endoscope device 100 and the processor 200 are connected via a scope connector 400. The scope connector 400 includes an LCB, which is part of an LCB101 extending from the processor 200 to the endoscope device 100, and a scope connector circuit 401. In this embodiment, the scope connector circuit 401 is disposed within the scope connector 400, but this circuit does not necessarily have to be located within the scope connector 400. For example, a circuit equivalent to the scope connector circuit 401 may be disposed in a connector on the processor 200 side or inside the processor 200.

[0049] <Example of the internal structure of the light source device 201>

[0050] Figure 3 This is a diagram illustrating an example of the internal configuration of a light source device 201, for example, disposed inside a processor 200.

[0051] The light source device 201 includes: a green LED 2011 that emits green light, a blue LED 2012 that emits blue light, a red LED 2013 that emits red light, an amber LED 2014 that emits amber light, a UV LED 2015 that emits UV light, a light source control unit 2016 for controlling the emission of light from each of the LEDs 2011 to 2015, and orthogonal prisms 2017 and 2018.

[0052] When the light source control unit 2016 receives an exposure control signal from the system controller 202, it changes the emission profile of each LED by controlling the emission period and applied current value of each currently emitting LED (the combination of emitting LEDs is determined according to the observation mode) and performs exposure adjustment (light intensity adjustment) (see below). Figure 12For example, after changing the light emission profile by one level, the light source control unit 2016 determines whether to change the light emission profile again to adjust the exposure based on the exposure control signal determined by the light measurement result of the light metering unit 203 (a comparison result after comparing with an appropriate brightness value).

[0053] Furthermore, the light source control unit 2016 determines the combination of LEDs to emit light based on a mode selection signal, which indicates the observation mode selected by the operator. At the start of the emission phase, the light source control unit 2016 controls the emission of each LED according to, for example, a predetermined emission profile (default emission period and drive current value), and then performs exposure adjustments as described above.

[0054] <About the various LED light sources>

[0055] Figure 4 This is a graph showing the spectral (wavelength characteristics) of each LED from 2011 to 2015. Furthermore, Figure 5 This is a diagram showing the characteristics of the illumination light (light used to illuminate the observation area) generated by passing each LED through orthogonal prisms 2017 and 2018.

[0056] The green LED 2011 has a transmission band of 540nm to 575nm, a peak wavelength of 550nm, and a half-width of 30nm. For example... Figure 4 As shown, a phosphor is mounted on the green LED 2011, through which light with a transmission wavelength range of approximately 400nm to 780nm is emitted. That is, white light is essentially emitted through the green LED and phosphor, but this white light is an intermediate product. As described later, the transmission band is narrowed by the orthogonal prism 2018, and the green light is then directed onto the observation area. The blue LED 2012 has a transmission band of 460nm to 490nm, a peak wavelength of 456nm, and a half-width of 21nm. The red LED 2013 has a transmission band of 630nm to 1000nm, a peak wavelength of 650nm, and a half-width of 20nm. The amber LED 2014 has a transmission band of 600nm to 615nm, a peak wavelength of 613nm, and a half-width of 19nm. The UV LED 2015 has a transmission band of 385nm to 425nm, a peak wavelength of 405nm, and a half-width of 14nm.

[0057] When the light emitted from each of the LEDs 2011 to 2015, including the green LED 2011 equipped with a phosphor (white light, blue light, red light, amber light, and UV light as intermediate products), passes through the orthogonal prisms 2017 and 2018, it will become... Figure 5The various types of light, exhibiting the characteristics shown, are irradiated onto the observation area. Specifically, the white light emitted from the green LED2011 + phosphor is confined to the transmission band by the orthogonal prism 2018, becoming green light in the range of 520nm to 595nm. The blue light emitted from the blue LED2012 is transformed into blue light in the range of 440nm to 500nm by the orthogonal prisms 2017 and 2018. Furthermore, the red light emitted from the red LED2013 is transformed into red light in the range of 620nm to 630nm by the orthogonal prisms 2017 and 2018. The amber light emitted from the amber LED2014 is transformed into amber light in the range of 580nm to 630nm by the orthogonal prisms 2017 and 2018. Further, the UV light emitted from the UV LED2015 is transformed into UV light in the range of 380nm to 450nm by the orthogonal prism 2018.

[0058] <Correction of linearity difference for each LED>

[0059] In the case where the light source device 201 is composed of multiple LEDs, not only are there differences in the wavelengths of the light emitted by each LED 2011 to 2015, but there are also differences in the light distribution (photometric distribution in each direction) (see reference). Figure 6 (Example of a light source configuration using LEDs with different light distributions). The color and light distribution of the emitted light from each LED 2011 to 2015 may vary. Furthermore, depending on the LED type, when the forward voltage is reduced to decrease the drive current, the drive current drops sharply, and the LED stops emitting light; therefore, sometimes the drive current cannot be reduced significantly. To address this situation, the linearity of the emitted light quantity / current ratio of each LED 2011 to 2015 must be dynamically corrected by controlling the drive current of each LED 2011 to 2015.

[0060] However, since the process of dynamically correcting linearity errors is complex, it is preferable to predetermine the drive current value to avoid linearity errors. Therefore, in this embodiment, a calibration table for correcting the linearity of the emitted light quantity / current ratio is prepared in advance, and the drive current value of each LED 2011 to 2015 is determined using this calibration table. Figure 7 This is a graph showing the emitted light quantity / current ratio of each LED. Figure 7 In this example, only the relationship between two LEDs (LED1 and LED2) is shown, but the same applies when using the five LEDs 2011 to 2015 shown in this embodiment. Figure 7The emitted light intensity / current ratio of each LED can be obtained by pre-measuring each LED. Therefore, as a correction value, a correction table (stored in memory) is prepared in advance, using the reciprocal of the emitted light intensity / current ratio as the correction parameter. The light source control unit 2016 calculates the corrected drive current value by multiplying it by the correction parameter corresponding to the desired emitted light intensity (the target emitted light intensity obtained through exposure adjustment), and drives each LED. In this way, even when the wavelength or light distribution of the emitted light from each LED is different, the linearity of the emitted light intensity / current ratio can be appropriately controlled.

[0061] <Example of the configuration of the imaging surface of an imaging element>

[0062] Figure 8 This diagram illustrates the effective pixel area and ineffective area of ​​a rolling shutter imaging element, using a CMOS sensor as an example. The CMOS sensor includes an effective pixel area that can be captured and an ineffective area that cannot. Furthermore, a portion (peripheral area) of the effective pixel area is obscured, effectively becoming an area where an image signal cannot be acquired. When shooting with such an imaging element (in the case of global exposure), various phenomena (features) appear in the captured image. Additionally, in this embodiment, the period not displayed on the screen is defined as the global exposure period, but the technical concept of this embodiment is not limited to this.

[0063] <General dimming control processing>

[0064] Figure 9 This is a diagram illustrating a typical dimming control process (example) and the observed images acquired in each frame (example).

[0065] like Figure 9As shown, frames F1 and F2 can be observed with appropriate light intensity (the metering results are appropriate). Furthermore, during the pseudo-global exposure period between frames F2 and F3, the amount of light illuminating the subject is insufficient due to the sudden movement of the endoscope tip away from the subject, resulting in a darker image in frame F3. The amount of light acquired when the image in frame F3 is dominated by the light emitted during the pseudo-global exposure period between the previous frame (frame F2) and the current frame (frame F3) (strong light emission: also known as main light emission). Therefore, when the distance to the subject changes after the pseudo-global exposure period, light emission (dimming control) that follows this distance change is executed starting from the next frame (frame F4). Thus, during the pseudo-global period between frames F3 and F4, dimming control is progressively executed based on the metering results (light emission control is progressively executed over time (frames F4→F5→F6) (changing the light emission profile)), determining an appropriate amount of light (light intensity increase control), and illuminating the subject with an appropriate amount of light. After the endoscope tip is moved away from the subject (between F2 and F3), an observation image based on the appropriate amount of light can be acquired in frame F5.

[0066] During the pseudo-global exposure period between frames F5 and F6, the distance between the endoscope tip and the subject is the same as in the previous frame F5, resulting in illumination with the same outline as during the pseudo-global exposure period between frames F4 and F5. Therefore, the observed image obtained in frame F6 is identical to the observed image obtained in frame F5. However, in reality, during the pixel readout period of frame F6 (during the rolling shutter), the endoscope tip suddenly approaches the subject. Therefore, the amount of illumination based on the latest illumination outline is unsuitable for the observation of the next frame, leading to excess illumination and a halo effect in the image of frame F7. This is because the amount of illumination (illumination outline) during the pseudo-global exposure period between frames F6 and F7 is determined based on the metering results of the image acquired in frame F6 (the metering results of the observed image in frame F6 are appropriate). Moreover, only after obtaining the metering results of the observed image in frame F7, which results in excess illumination, can the excess illumination caused by the sudden approach to the subject (including collision) be corrected. That is, the emission profile changes for the first time during the pseudo-global exposure between frames F7 and F8 (and changes gradually as the light intensity decreases, just as it does when the light intensity increases).

[0067] As described above, according to standard dimming control procedures, when the endoscope tip suddenly approaches the subject, the dimming control (amount reduction) is delayed by one frame. In the event of this sudden approach, excessive light results in a halo effect on the observed image, which is very difficult for the operator to observe.

[0068] This embodiment discloses a method for correcting the defects of the above-mentioned general dimming control (delay in the change of the light emission profile).

[0069] <Dimming control processing involved in this embodiment>

[0070] (i) Control Example 1

[0071] Figure 10 This is a diagram illustrating the dimming control processing of Control Example 1 of this embodiment (example) and the observed images acquired in each frame (example). Additionally, in Figure 10 In order to differentiate from general dimming control processing ( Figure 9 The distance between the endoscope tip and the subject is changed in the same way as the comparison.

[0072] Control Example 1 differs from typical dimming control processing in that it involves globally executing a weak pre-illumination (continuous light) dimming control process. In Control Example 1, the sum of the illumination time and illumination level of the weak pre-illumination (continuous light) is sufficiently smaller than the sum of the illumination time and illumination level of the strong illumination during pseudo-global exposure. Furthermore, this pre-illumination is an illumination with an intensity that allows unwanted phenomena (e.g., distortion or artifacts such as scan line noise) caused by rolling shutter to be ignored by the illumination (pre-illumination), and that the intensity of the illumination (pre-illumination) can be identified when the endoscope tip suddenly approaches the subject. Specifically, the sum of the illumination time and illumination level of the pre-illumination can be 10% or less of the sum of the illumination time and illumination level of the strong illumination, preferably 2% or less, and more preferably 1% or less.

[0073] In the dimming control process based on Control Example 1 (continuous pre-emission), such as Figure 10 As shown, when the tip of the endoscope is far from the subject, the same general dimming control process as described above is performed (refer to...). Figure 9The same process applies. That is, for example, frames F1 and F2 can be observed with appropriate light intensity (the metering results are appropriate). Furthermore, during the pseudo-global exposure period between frames F2 and F3, the amount of light illuminating the subject is insufficient because the endoscope tip suddenly moves away from the subject, resulting in a darker image in frame F3. The amount of light acquired when the image in frame F3 is dominated by the light emitted during the pseudo-global exposure period between the previous frame (frame F2) and the current frame (frame F3). Therefore, if the distance to the subject changes after the pseudo-global exposure period, the next frame (frame F4) performs (reflects) light emission (dimming control) that follows this distance change. Moreover, during the pseudo-global period between frames F3 and F4, dimming control is performed progressively based on the metering results (light emission control is performed progressively over time (frames F4→F5→F6) (changing the light emission profile)), determining an appropriate amount of light (light intensity increase control), and illuminating the subject with an appropriate amount of light. After the endoscope tip is moved away from the subject (between F2 and F3), an observation image based on appropriate light intensity can be acquired in frame F5. Furthermore, the metering result can be either the metering value of the central portion of the observation image or the average of the metering values ​​of all pixels.

[0074] During the pseudo-global exposure period between frames F5 and F6, the distance between the endoscope tip and the subject is the same as in the previous frame F5, thus emitting light with the same outline as during the pseudo-global exposure period between frames F4 and F5. However, during the pixel readout period of frame F6 (during the rolling shutter), a weak pre-illumination is performed, so that if the endoscope tip suddenly approaches the subject, the change in brightness of the observed image can be captured (detecting the approach of the subject). Therefore, the observed image obtained in frame F6 is brighter than the observed image obtained in frame F5; that is, the effect of excess light caused by the sudden approach of the endoscope tip to the subject during the pixel readout period of frame F6 (during the rolling shutter) immediately appears in the observed image. Therefore, when acquiring the observed image in the next frame F7, dimming control processing to reflect this excess light can be performed, and processing to reduce the strong luminescence level during the pseudo-global exposure period between frames F6 and F7 can be performed. However, instead of abruptly reducing it, the luminescence level is gradually reduced to make the brightness change more natural for the operator. For example, such as Figure 10 As shown, the luminance is first reduced to a predetermined value during the pseudo-global exposure period between frames F6 and F7, and then further reduced to the predetermined value during the next pseudo-global exposure period (between frames F7 and F8). The amount of luminance control (e.g., the reduction magnitude) can be a constant value or the luminance profile can be determined based on the degree of excess of the metering results relative to the appropriate value.

[0075] As described above, according to the dimming control process of Control Example 1, a weak pre-light emission (continuous light) is performed during pixel readout (during rolling shutter). Therefore, in response to changes in imaging conditions during pixel readout (e.g., the endoscope tip suddenly approaches the subject), dimming control can be implemented 1 frame earlier than in general dimming control processes, and the appropriate exposure level can be obtained (appropriate metering results can be obtained in advance).

[0076] (ii) Control Example 2

[0077] Figure 11 This is a diagram illustrating the dimming control processing of Control Example 2 of this embodiment (example) and the observed images acquired in each frame (example). Additionally, in Figure 11 In order to differentiate from general dimming control processing ( Figure 9 The distance between the endoscope tip and the subject is changed in the same way as the comparison.

[0078] Control Example 2 differs from general dimming control processing in that it is a dimming control process that globally executes a weak pre-illumination (pulse light). The value of the emission time × emission level of the weak pre-illumination (pulse light) in Control Example 2 is the same as in Control Example 1, and is sufficiently smaller than the value of the emission time × emission level of the strong emission during pseudo-global exposure. Furthermore, this pre-illumination is an emission with an intensity that allows the emission (pre-illumination) to ignore unwanted phenomena caused by rolling shutter (e.g., distortion or artifacts (scan line noise, etc.)), and that can be identified when the endoscope tip suddenly approaches the subject. Specifically, the value of the pre-illumination emission time × emission level can be less than 10% of the aforementioned value of the strong emission time × emission level, preferably less than 2%, and more preferably less than 1%. Additionally, in Control Example 2, pulse light is used as the weak pre-illumination, but the frequency of the pulse is set to a predetermined value or higher. For example, the frequency of the pulse light is set such that when the endoscope tip approaches the subject, the observed image does not appear striped, and the overall image becomes brighter (whiter).

[0079] The content and effect of the dimming control processing based on Control Example 2 are the same as those of the dimming control processing based on Control Example 1 described above, so its description is omitted.

[0080] (iii) Control Example 3

[0081] Figure 12 This is a diagram illustrating the dimming control processing of Control Example 3 of this embodiment (example) and the observed images acquired in each frame (example). Additionally, in Figure 12 In order to differentiate from general dimming control processing ( Figure 9 The distance between the endoscope tip and the subject is changed in the same way as the comparison.

[0082] Control Example 3 performs a weak pre-emission (continuous light) dimming control process only during a predetermined period of a portion of the pixel readout period (roll shutter period) (e.g., the last predetermined period of the roll shutter period (or the predetermined period immediately before the next pseudo global exposure period)).

[0083] In the dimming control processing based on Control Example 3 (the same as Control Example 4 described later), compared to Control Examples 1 and 2 (where pre-exposure is performed during the entire pixel readout (rolling shutter) period), when approaching the subject, double exposure is performed only in a predetermined area at the bottom of the image via pre-exposure. Therefore, according to Control Example 3, discomfort caused to the endoscope user due to double exposure can be reduced, and if the pre-exposure period is adjusted, it can be limited to an area within the observed image where banding caused by double exposure does not need to be considered. For example, if the frame rate is 60Hz (16.6ms) and the global exposure period (in Figure 12In a single frame, the second line from the top and bottom: the line covered by the electron mask and the line of invalid pixels. If the time interval is 2ms, then the remaining 14.6ms is the reading period for the valid lines. At this time, when pre-illumination is performed for 50% = 7.33ms of the valid line reading period, the boundary between the double-exposed area and the unexposed area is at the center of the image, which will cause greater discomfort to the operator. Therefore, for example, a) if 25% = 3.67ms or less, the boundary is located in the lower 1 / 4 of the image and is not noticeable compared to the center; furthermore, b) if 10% = 1.46ms or less, the boundary is located in the lower 1 / 10 of the image, and since it is only slightly reflected at the ends of the image, the operator will hardly notice it; furthermore, c) if it is only a few lines (e.g., less than 10 lines) in a predetermined area of ​​the image to be observed (e.g., the lower area), the boundary roughly coincides with the electron mask boundary, and the operator cannot identify a clear boundary. At this point, if the total value of the pre-illumination period × pre-illumination level is not sufficiently less than the illumination period × illumination level of the strong illumination during the pseudo-global exposure period, the aforementioned dividing line can be clearly seen. Under conditions such as a) or b) above, although the dividing line is not obvious, the operator can identify it; therefore, it needs to be sufficiently small compared to the strong illumination period × illumination level (e.g., illumination with an intensity such that undesirable phenomena (e.g., distortion or artifacts) caused by rolling shutter can be ignored by the pre-illumination, and the intensity of the illumination (pre-illumination) can be identified when the endoscope tip suddenly approaches the subject). Specifically, similar to Control Example 1 and Control Example 2, the value of the pre-illumination time × illumination level can be less than 10% of the aforementioned strong illumination time × illumination level value, preferably less than 2%, and more preferably less than 1%. On the other hand, under conditions such as c) above, since the operator cannot identify the dividing line, the pre-illumination intensity can be equal to (or greater than) the strong illumination intensity. That is, because the pre-emission period is short, it is easy to make its product with the pre-emission intensity smaller. However, it is not a problem to make it greater than the intensity of the strong emission period × the emission level, for example, by making the pre-emission instantaneously reach 1000 times the intensity of the strong emission.

[0084] In summary, regarding the amount of light to be emitted, in cases a) and b) above, the emission profile is controlled so that the total value (area value) of the pre-emission period × pre-emission level is less than 10%, less than 2%, or 1% of the value (area value) of the emission period × emission level of the strong emission (main emission). However, in case c) above, such a condition is not imposed, and the pre-emission level can be increased to an extreme degree (not subject to the constraints of the above conditions such as less than 10%), depending on its relationship with the lines read in the observed image.

[0085] In the dimming control process based on control example 3 (continuous pre-emission during a portion of the pixel readout period), such as Figure 12 As shown, when the tip of the endoscope is far from the subject, the same general dimming control process as described above is performed (refer to...). Figure 9 The same process applies. That is, for example, frames F1 and F2 can be observed with appropriate light intensity (the metering results are appropriate). Furthermore, during the pseudo-global exposure period between frames F2 and F3, the amount of light illuminating the subject is insufficient because the endoscope tip suddenly moves away from the subject, resulting in a darker image in frame F3. The amount of light acquired when the image in frame F3 is dominated by the light emitted during the pseudo-global exposure period between the previous frame (frame F2) and the current frame (frame F3) (strong light emission). Therefore, if the distance to the subject changes after the pseudo-global exposure period, the next frame (frame F4) performs (reflects) light emission (dimming control) that follows this distance change. Therefore, during the pseudo-global period between frames F3 and F4, dimming control is performed progressively based on the metering results (light emission control is performed progressively over time (frames F4→F5→F6) (changing the light emission profile)), determining an appropriate amount of light (light intensity increase control), and illuminating the subject with an appropriate amount of light. After the endoscope tip is moved away from the subject (between F2 and F3), an observation image based on the appropriate amount of light can be acquired in frame F5.

[0086] During the pseudo-global exposure period between frames F5 and F6, the distance between the endoscope tip and the subject is the same as in the previous frame F5, thus emitting light with the same outline as the emission during the pseudo-global exposure period between frames F4 and F5. However, during the final predetermined period of the pixel readout period (roll shutter period) of frame F6 (e.g., the period of reading the last k lines (where k = 1 to n: n is an integer obtained by rounding up 1% of the number of valid lines (first decimal place) (example)), a weak pre-emission emission (continuous light) is performed, thus enabling the capture of brightness changes in the observed image (detecting the approach of the subject) in the event that the endoscope tip suddenly approaches the subject. Figure 12 As shown, in the observation image of frame F6, the portion (region 1201) formed by pixels read during the pre-illumination period appears whiter (brighter) compared to other portions. That is, during the pixel reading period of frame F6 (during the rolling shutter), the effect of excessive light caused by the sudden approach of the endoscope tip to the subject immediately appears in a portion of the observation image. Therefore, when acquiring the observation image in the next frame F7, dimming control processing to reflect this excessive light can be performed, and processing to reduce the strong luminescence level during the pseudo-global exposure period between frames F6 and F7 (adjusting for appropriate exposure) can be performed. However, instead of abruptly reducing it, the luminescence level is gradually reduced to make the change in brightness more natural for the operator. For example, as... Figure 12 As shown, the luminance is first reduced to a predetermined value during the pseudo-global exposure period between frames F6 and F7, and then further reduced to the predetermined value during the next pseudo-global exposure period (between frames F7 and F8). The amount of luminance control (e.g., the reduction magnitude) can be a constant value or the luminance profile can be determined based on the degree of excess of the metering results relative to the appropriate value.

[0087] As described above, according to the dimming control processing of Control Example 3, a weak pre-illumination (continuous light) is performed only during a predetermined period of the pixel readout period (roll shutter period) (e.g., the last predetermined period of the roll shutter period (or the predetermined period immediately before the next pseudo global exposure period)). Therefore, in response to changes in imaging conditions during the pixel readout period (e.g., the endoscope tip suddenly approaches the subject), dimming control can be implemented 1 frame earlier than in general dimming control processing, and the appropriate exposure level can be obtained (appropriate metering results can be obtained in advance).

[0088] (iv) Control Example 4

[0089] Figure 13 This is a diagram illustrating the dimming control processing of Control Example 4 of this embodiment (example) and the observed images acquired in each frame (example). Additionally, in Figure 13 In order to differentiate from general dimming control processing ( Figure 9 The distance between the endoscope tip and the subject is changed in the same way as the comparison.

[0090] Control Example 4 performs dimming control processing for a weak pre-light emission (pulsed light) only during a predetermined period of a portion of the pixel readout period (roll shutter period) (e.g., the last predetermined period of the roll shutter period (or the predetermined period immediately preceding the next pseudo-global exposure period)). The value of the emission time × emission level of the weak pre-light emission in Control Example 4 is the same as in Control Examples 1 to 3, and is sufficiently smaller than the value of the emission time × emission level of the strong emission during the pseudo-global exposure period. Furthermore, this pre-light emission is an emission intensity that allows unwanted phenomena (e.g., distortion or artifacts (scan line noise, etc.)) caused by the roll shutter to be ignored by the emission (pre-light emission), and that the intensity of the emission (pre-light emission) can be identified when the endoscope tip suddenly approaches the subject. Specifically, the value of the pre-light emission time × emission level can be less than 10% of the aforementioned value of the strong emission time × emission level, preferably less than 2%, and more preferably less than 1%. Additionally, in Control Example 4, pulsed light is used as the weak pre-light emission, but the frequency of the pulse is set to a predetermined value or higher. For example, the frequency of the pulsed light is set such that when the tip of the endoscope approaches the subject, a portion of the observed image (area 1301) becomes brighter (whiter).

[0091] The content and effect of the dimming control processing based on Control Example 4 are the same as those of the dimming control processing based on Control Example 3 described above, so its description is omitted.

[0092] <Dim control processing in Control Examples 1 and 2: Flowchart>

[0093] Figure 14 This is a flowchart illustrating the dimming control process of Control Example 1 and Control Example 2 in this embodiment. Although the following steps are mainly described with the system controller 202 as the main operator, the present invention is not limited thereto, and a control unit (processor) for performing action control or calculation processing may also be provided and made to perform the operation. Furthermore, the light source control unit 2016 of the light source device 201 may be configured to have the functions of the system controller 202. Therefore, the dimming control process may be part of the overall operation of the endoscope system 1 or part of the operation of the light source device 201. In this case, the light source control unit 2016 becomes the main operator of each step.

[0094] (i) Step 1401

[0095] The light source control unit 2016 receives a mode selection signal from the system controller 202 corresponding to the observation mode selected by the operator, and uses the above-mentioned calibration table to correct the linearity of the emitted light quantity / current ratio of each light source (any combination of green LED 2011 to UV LED 2015) for each light source to emit light.

[0096] (ii) Step 1402

[0097] The light source control unit 2016 drives each light source to emit light using a drive current linearly corrected for the emitted light quantity / current ratio, generating illumination light and illuminating the subject. Furthermore, the strong emission profile during the pseudo-global exposure period can be set to a predetermined value (default value), or the emission profile used in the last operation during the last use of the endoscope can be used. Moreover, as described above, the emission profile is determined such that the emission period × emission level of the weak pre-emission (continuous light or pulsed light) during the pixel readout period (rolling shutter period) is less than 10%, less than 2%, or less than 1% (see reference) of the emission period (which can also be shorter than the pseudo-global exposure period) × emission level of the strong emission during the pseudo-global exposure period. Figure 10 and Figure 11 ).

[0098] (iii) Step 1403

[0099] The imaging element (e.g., a CMOS sensor) of the imaging unit 103 detects the reflected light from the subject (observation area) generated by illuminating the subject with illumination light, and sends the imaging image signal to the processor 200 via the lens connector circuit 401. Furthermore, the system controller 202 begins acquiring data for one frame of image (each pixel) via the metering unit 203.

[0100] (iv) Step 1404

[0101] System controller 202 determines whether the acquired pixel (input pixel) is a valid pixel (refer to...). Figure 8 (Pixels in the effective area of ​​the CMOS sensor). If the acquired pixel is a valid pixel (if "Yes" is true in step 1404), the process proceeds to step 1405. On the other hand, if the acquired pixel is not a valid pixel (invalid pixel or valid but masked pixel: if "No" is true in step 1404), the process proceeds to step 1406.

[0102] (v) Step 1405

[0103] The system controller 202 accumulates the photometric values ​​(brightness values) of each effective pixel obtained from the photometer unit 203.

[0104] (vi) Step 1406

[0105] The system controller 202 determines whether one frame of valid pixels has been acquired. If one frame of valid pixels has been acquired (if "yes" in step 1406), the process proceeds to step 1407. On the other hand, if one frame of valid pixels has not been acquired (if "no" in step 1406), the process returns to step 1403.

[0106] (vii) Step 1407

[0107] The system controller 202 compares the accumulated metering value of one frame with a predetermined threshold and determines whether the exposure is appropriate. If the metering value is determined to be appropriate (if "yes" in step 1407), the dimming control process ends. On the other hand, if the metering value is determined to be inappropriate (e.g., excessive light due to sudden approach to the subject or insufficient light due to distance from the subject) (if "no" in step 1407), the process proceeds to step 1408.

[0108] (viii) Step 1408

[0109] The system controller 202 changes the emission profile and sends the emission profile to the light source control unit 2016 of the light source device 201. The change of the emission profile may be, for example, by reducing or increasing a predetermined amount of light, or the profile may be determined based on the degree of excess or deficiency relative to an appropriate value.

[0110] Furthermore, the changing patterns of the emission profile can also be pre-stored in a memory (not shown) (e.g., a table is created), and the system controller 202 determines the emission profile based on the deviation between the measured photometric value and the appropriate photometric value (e.g., 3dB excess → emission mode 1, 6dB excess → emission mode 2, 3dB deficiency → emission mode 3, ... etc.).

[0111] Furthermore, as a change to the emission profile, the emission level (and / or emission period) of the strong emission during the pseudo-global exposure can be gradually increased or decreased every frame time (e.g., 60Hz = 16.6ms) (see [reference]). Figure 10 and Figure 11 (F6→F7→F8). This avoids drastic changes in brightness, thus allowing for the acquisition of natural-looking images.

[0112] <Dim control processing in examples 3 and 4: Flowchart>

[0113] Figure 15 This is a flowchart illustrating the dimming control processing of Control Examples 3 and 4 in this embodiment. Although the following steps are primarily described with the system controller 202 as the main operator, the present invention is not limited thereto; a control unit (processor) for performing action control or computational processing may also be provided and executed. Furthermore, the light source control unit 2016 of the light source device 201 may be configured to have the functions of the system controller 202. Therefore, the dimming control processing can be part of the overall operation of the endoscope system 1 or part of the operation of the light source device 201. In this case, the light source control unit 2016 becomes the main operator of each step.

[0114] (i) Step 1501

[0115] The light source control unit 2016 receives a mode selection signal from the system controller 202 corresponding to the observation mode selected by the operator, and uses the above-mentioned calibration table to correct the linearity of the emitted light quantity / current ratio of each light source (any combination of green LED 2011 to UV LED 2015) for each light source to emit light.

[0116] (ii) Step 1502

[0117] The light source control unit 2016 drives each light source to emit light using a drive current linearly corrected for the emitted light quantity / current ratio, generating illumination light and illuminating the subject. Furthermore, the strong emission profile during the pseudo-global exposure period can be set to a predetermined value (default value), or the emission profile used in the last operation during the last use of the endoscope can be used. In addition, in control examples 3 and 4, a weak pre-emission emission (continuous light or pulsed light) is performed during a portion of the pixel readout period (roll shutter period) (the last predetermined period of the pixel readout period). As described above, the emission profile is determined such that the emission period × emission level of this weak pre-emission emission is less than 10%, less than 2%, or less than 1% (see reference) of the emission period × emission level of the strong emission period during the pseudo-global exposure period (which may also be shorter than the pseudo-global exposure period). Figure 10 and Figure 11 ).

[0118] (iii) Step 1503

[0119] The imaging element (e.g., a CMOS sensor) of the imaging unit 103 detects the reflected light from the subject (observation area) generated by illuminating the subject with illumination light, and sends the imaging image signal to the processor 200 via the lens connector circuit 401. Furthermore, the system controller 202 begins acquiring data for one frame of image (each pixel) via the metering unit 203.

[0120] (iv) Step 1504

[0121] System controller 202 determines whether the acquired pixel (input pixel) is a valid pixel (refer to...). Figure 8 (Pixels in the effective area of ​​the CMOS sensor). If the acquired pixel is a valid pixel (if "Yes" is true in step 1504), the process proceeds to step 1505. On the other hand, if the acquired pixel is not a valid pixel (invalid pixel or valid but masked pixel: if "No" is true in step 1504), the process proceeds to step 1509.

[0122] (v) Step 1505

[0123] The system controller 202 determines whether the acquired (input) valid pixels are pixels in the row to be illuminated. The read row number in the frame (image) and the timing of the weak pre-illumination are predetermined. For example, the row number and illuminating MIG information are stored in the internal memory of the system controller 202 or in a memory not shown. Therefore, the system controller 202 can determine on which row the weak pre-illumination should be performed.

[0124] If it is determined that the acquired pixel is a pixel used to form the pre-illumination row (if "yes" is true in step 1505), the process proceeds to step 1506. On the other hand, if it is determined that the acquired pixel is not related to the pre-illumination row (if "no" is true in step 1505), the process proceeds to step 1507.

[0125] (vi) Step 1506

[0126] The system controller 202 accumulates the brightness values ​​of the pixels in the row used to perform weak pre-illumination and obtains a pre-illumination metering value (since the pre-illumination row is also affected by the strong illumination during pseudo-global exposure, it is the metering value of the strong illumination plus the weak pre-illumination). That is, the brightness values ​​of each pixel constituting the row related to pre-illumination are accumulated pixel by pixel, and finally, the pre-illumination metering value for one frame is calculated. Furthermore, the pre-illumination metering value for one frame is stored in the internal memory of the system controller 202 or in a memory not shown.

[0127] (vii) Step 1507

[0128] The system controller 202 accumulates the brightness values ​​of input pixels other than the pre-illumination row and calculates the normal illumination metering value based on the strong illumination during pseudo-global exposure. That is, the brightness values ​​of each pixel used to form rows other than the pre-illumination row are accumulated pixel-by-pixel to finally calculate the normal illumination metering value for one frame. Furthermore, the normal illumination metering value for one frame is stored in the internal memory of the system controller 202 or in a memory not shown.

[0129] (viii) Step 1508

[0130] The system controller 202 adds the pre-luminescence photometric value calculated in step 1506 and the normal luminescence photometric value calculated in step 1507 to calculate the overall photometric value of one frame (assuming).

[0131] (ix) Step 1509

[0132] The system controller 202 determines whether one frame of valid pixels has been acquired. If the acquisition of one frame of valid pixels has been completed (if "yes" in step 1509), the process proceeds to step 1510. On the other hand, if the acquisition of one frame of valid pixels has not been completed (if "no" in step 1509), the process returns to step 1503. Furthermore, if "yes" in step 1509, the overall metering value of one frame (assumed) obtained in step 1508 is the overall metering value of one frame (determined).

[0133] (x) Step 1510

[0134] The system controller 202 compares the overall metering value of one frame (determines) with a predetermined threshold (overall metering threshold) and determines whether it is an appropriate metering value. Alternatively, the overall metering threshold can also be a value with a predetermined width (range).

[0135] If the overall metering value of a frame is determined to be appropriate (if "Yes" is true in step 1510), the process proceeds to step 1511. On the other hand, if the overall metering value of a frame is determined to be inappropriate (if "No" is true in step 1510), the process proceeds to step 1512.

[0136] (xi) Step 1511

[0137] The system controller 202 acquires the aforementioned pre-emission photometric value in the frame, compares it with a predetermined threshold (pre-emission threshold), and determines whether it is an appropriate photometric value. Furthermore, the pre-emission threshold and the overall photometric threshold are the same, and can be values ​​with a predetermined width (range).

[0138] If the pre-emission photometric value is determined to be appropriate (if "Yes" is indicated in step 1511), the dimming control process ends. On the other hand, if the pre-emission photometric value is determined to be inappropriate (if "No" is indicated in step 1511), the process proceeds to step 1512.

[0139] (xii) Step 1512

[0140] The system controller 202 changes the emission profile and sends the emission profile to the light source control unit 2016 of the light source device 201. The change of the emission profile may be, for example, by reducing or increasing a predetermined amount of light, or the profile may be determined based on the degree of excess or deficiency relative to an appropriate value.

[0141] Alternatively, the changing patterns of the emission profile can be pre-stored in a memory (e.g., a table) and the system controller 202 determines the emission profile based on the deviation between the measured photometric value and the appropriate photometric value (e.g., 3dB excess → emission mode 1, 6dB excess → emission mode 2, 3dB deficiency → emission mode 3, etc.).

[0142] Furthermore, as a change to the emission profile, the emission level (and / or emission period) of the strong emission during the pseudo-global exposure can be gradually increased or decreased every frame time (e.g., 1 / 30th of a second) (see [reference]). Figure 12 and Figure 13 (F6→F7→F8). This avoids drastic changes in brightness, thus allowing for the acquisition of natural-looking images.

[0143] <Effects of the Implementation Method>

[0144] According to this embodiment, the exposure (the brightness component of the weak pre-emission light) when the endoscope tip (image sensor) suddenly approaches the subject during the rolling shutter is added to the metering result. Considering light intensity, since the brightness component of the strong emission (main emission) during pseudo-global exposure is overwhelmingly greater than the brightness component of the weak pre-emission light during the rolling shutter, the brightness component of the strong emission dominates in the formation of the observed image (however, the emission profile of the strong emission is determined because the distance between the image sensor and the subject is greater than when suddenly approaching, and this is appropriate). On the other hand, when performing weak pre-emission light, when the image sensor suddenly approaches the subject, the entire observed image (control examples 1 and 2) or a portion (the lower portion of the observed image: control examples 3 and 4) turns white, and the metering result based on the weak pre-emission light immediately appears in the observed image, allowing for immediate detection of excess light. Therefore, the dimming control processing according to this embodiment can quickly respond to changes during the rolling shutter (pixel readout period) and perform light control. Furthermore, in cases a) and b) of Control Examples 1 and 2, and Control Examples 3 and 4, the weak pre-illumination is controlled to be less than 10% (preferably less than 2%, more preferably less than 1%) of the main illumination, regarding the value of illumination period × illumination level. Therefore, distortion and artifacts caused by the rolling shutter of the imaging element can be avoided. Furthermore, in case c) of Control Examples 3 and 4, since the pre-illumination period is limited to the period of reading several rows of pixels used to form the lower part of the observed image, even if the illumination level of the pre-illumination is greater than the illumination level of the main illumination, it will not cause discomfort to the operator, and it is possible to quickly detect whether there is excess light in the observed image.

[0145] <Specific matters in this disclosure>

[0146] (1) Specific Item 1

[0147] A light source device is a device for generating illumination light to illuminate a subject, comprising:

[0148] Multiple semiconductor light-emitting elements are used to emit light in different wavelengths;

[0149] and a control unit, which controls the light emission profile of the plurality of semiconductor light-emitting elements and drives the plurality of semiconductor light-emitting elements;

[0150] The control unit controls the light emission profiles of the plurality of semiconductor light-emitting elements to perform main light emission during the pseudo-global exposure of the imaging element and to perform pre-light emission during at least a portion of the pixel readout period of the imaging element.

[0151] The emission level of the pre-emission emission is lower than the emission level of the main emission emission.

[0152] (2) Specific Item 2

[0153] A light source device, in specific item 1,

[0154] The sum of the pre-light emission period × emission level is sufficiently less than the sum of the main light emission period × emission level and reaches a level where noise caused by the rolling shutter of the camera element can be ignored.

[0155] (3) Specific Items 3

[0156] A light source device, in particular item 1 or 2,

[0157] The control unit controls the total value of the pre-light emission period × emission level to be less than 10% of the value of the main light emission period × emission level.

[0158] (4) Specific Items 4

[0159] A light source device, wherein, in any one of the specific items 1 to 3,

[0160] The control unit controls the light emission profile so that the pre-emission is configured as continuous light or pulsed light throughout the entire period of the pixel reading.

[0161] (5) Specific Items 5

[0162] A light source device, wherein, in any one of the specific items 1 to 4,

[0163] The control unit compares the metering value of one frame of the observed image of the subject with a first threshold and determines whether to change the luminous contour.

[0164] (6) Specific Items 6

[0165] A light source device, in specific item 5,

[0166] When the photometric value is greater than the first threshold and there is excess light, the control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

[0167] (7) Specific Items 7

[0168] A light source device, in particular item 1 or 2,

[0169] The control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during pixel reading of pixels in the lower 25% or less of the observed image of the subject.

[0170] (8) Specific Items

[0171] A light source device, in specific item 7,

[0172] The control unit controls the total value of the pre-light emission period × emission level to be less than 10% of the value of the main light emission period × emission level.

[0173] (9) Specific Items 9

[0174] A light source device, in particular item 1 or 2,

[0175] The control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during the pixel reading of a predetermined number of rows of pixels constituting the observed image of the subject.

[0176] (10) Specific Items 10

[0177] A light source device, in specific item 9,

[0178] The control unit controls the light emission profile to perform the pre-emission of the continuous light or the pulsed light during the pixel reading of the pixels constituting the final predetermined number of rows of pixels in the observed image.

[0179] (11) Specific Items 11

[0180] A light source device, in any one of the specific items 7 to 10,

[0181] The control unit compares the metering value based on the pre-emission emission in one frame of the observed image of the subject with a second threshold, and determines whether to change the emission profile.

[0182] (12) Specific Items 12

[0183] A light source device, in specific item 11,

[0184] When the photometric value is greater than the second threshold and there is excess light, the control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

[0185] (13) Specific Items 13

[0186] An endoscope system is an endoscope system that inserts an endoscope into an object of observation and acquires images of the object, comprising:

[0187] Multiple semiconductor light-emitting elements are used to emit light in different wavelengths;

[0188] An imaging element for illuminating the subject with illumination light and detecting reflected light from the subject to generate an image signal;

[0189] A processor for processing the image signal to generate an image of the subject and displaying it on a monitor; a main control unit for generating control signals based on the image signal to control the light emission profiles of the plurality of semiconductor light-emitting elements;

[0190] And a light source control unit, which is used to receive the control signal from the main control unit and drive the plurality of semiconductor light-emitting elements with a drive signal corresponding to the light emission profile;

[0191] The main control unit controls the light emission profiles of the plurality of semiconductor light-emitting elements to perform main light emission during the pseudo-global exposure of the imaging element and to perform pre-light emission during at least a portion of the pixel readout period of the imaging element.

[0192] The emission level of the pre-emission emission is lower than the emission level of the main emission emission.

[0193] (14) Specific Items

[0194] An endoscope system, in specific item 13,

[0195] The sum of the pre-light emission period × emission level is sufficiently less than the sum of the main light emission period × emission level and reaches a level where noise caused by the rolling shutter of the camera element can be ignored.

[0196] (15) Specific Items 15

[0197] An endoscope system, in specific items 13 or 14,

[0198] The main control unit controls the total value of the pre-light emission period × emission level to be less than 10% of the value of the main light emission period × emission level.

[0199] (16) Specific Items 16

[0200] An endoscope system, in any one of items 13 to 15,

[0201] The main control unit controls the light emission profile so that the pre-emission configuration is continuous light or pulsed light throughout the entire period of the pixel reading period.

[0202] (17) Specific Items 17

[0203] An endoscope system, in any one of items 13 to 16,

[0204] The main control unit compares the metering value of one frame of the observed image of the subject with a first threshold, and determines whether to change the luminous contour.

[0205] (18) Specific Matters

[0206] An endoscope system, in specific item 17,

[0207] When the photometric value is greater than the first threshold and there is excess light, the main control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

[0208] (19) Specific Matters 19

[0209] An endoscope system, in specific items 13 or 14,

[0210] The main control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during pixel reading of pixels in the lower 25% or less of the observed image of the subject.

[0211] (20) Specific Matters 20

[0212] An endoscope system, in specific item 19,

[0213] The main control unit controls the total value of the pre-light emission period × emission level to be less than 10% of the value of the main light emission period × emission level.

[0214] (21) Specific Matters 21

[0215] An endoscope system, in specific items 13 or 14,

[0216] The main control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during the pixel reading of a predetermined number of rows of pixels constituting the observed image of the subject.

[0217] (22) Specific Matters 22

[0218] An endoscope system, in specific item 21,

[0219] The main control unit controls the light emission profile to perform the pre-emission of the continuous light or the pulsed light during the pixel reading of the pixels constituting the final predetermined number of rows of pixels in the observed image.

[0220] (23) Specific Matters

[0221] An endoscope system, in any one of items 19 to 22,

[0222] The main control unit compares the photometric value based on the pre-emission emission in one frame of the observed image of the subject with the second threshold, and determines whether to change the emission profile.

[0223] (24) Specific Matters

[0224] An endoscope system, in specific item 23,

[0225] When the photometric value is greater than the second threshold and there is excess light, the main control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

[0226] <Other>

[0227] The functions described in this embodiment can also be implemented using software program code. In this case, a storage medium containing program code is provided to a system or device, and the computer (or CPU or MPU) of the system or device reads the program code stored in the storage medium. In this case, the program code read from the storage medium itself implements the functions of the aforementioned embodiment, and the program code itself and the storage medium storing it constitute this disclosure. Examples of storage media used to provide such program code include floppy disks, CD-ROMs, DVD-ROMs, hard disks, optical disks, magneto-optical disks, CD-Rs, magnetic tapes, non-volatile memory cards, ROMs, etc.

[0228] Furthermore, according to the instructions of the program code, the OS (operating system) running on the computer may execute part or all of the actual processing, and the functions of the aforementioned embodiments may be realized through this processing. Further, after the program code read from the storage medium is written into the computer's memory, the computer's CPU or other processor may execute part or all of the actual processing according to the instructions of the program code, and the functions of the aforementioned embodiments may be realized through this processing.

[0229] Furthermore, the program code of the software that implements the functions of this embodiment can also be distributed via a network and stored in a storage unit such as a hard disk or memory of the system or device, or in a storage medium such as a CD-RW or CD-R. When in use, the computer (or CPU or MPU) of the system or device reads and executes the program code stored in the storage unit or storage medium.

[0230] Finally, the methods and techniques described herein are not substantially related to any particular device, but can be implemented by any suitable combination of components. Furthermore, various types of devices for general purposes can be used in accordance with the teachings described herein. It is understood that constructing a dedicated device is advantageous for performing the steps of the methods described herein. Moreover, various forms can be formed by appropriate combinations of the various constituent elements disclosed in this embodiment. For example, some constituent elements can be removed from all the constituent elements shown in this embodiment. Furthermore, the constituent elements involved in different embodiments can be appropriately combined. Although this disclosure has been described in conjunction with specific examples, it should not be limited to all aspects. Those skilled in the art will understand that there are various combinations of hardware, software, and firmware suitable for implementing the techniques of this disclosure. For example, the described software can be implemented by various programming or scripting languages ​​such as assembly language, C / C++, Perl, Shell, PHP, Java (registered trademark).

[0231] Furthermore, in the above embodiments, control lines or information lines are shown for illustrative purposes only, and not all control lines or information lines are necessarily shown in the actual product. All configurations can be interconnected.

[0232] [Symbol Explanation]

[0233] 1. Endoscopic system

[0234] 100 Endoscopic Devices

[0235] 103 camera units

[0236] 200 processors

[0237] 201 Light Source Device

[0238] 2011 Green LED

[0239] 2012 Green LED

[0240] 2013 red LED

[0241] 2014 Amber LED

[0242] 2015 UV LED

[0243] 2016 Light Source Control Department

[0244] Orthogonal prisms in 2017 and 2018

[0245] 202 System Controller

[0246] 203 Metering Section

[0247] 300 monitor.

Claims

1. A light source device for generating illumination light to illuminate a subject, comprising: Multiple semiconductor light-emitting elements are used to emit light in different wavelengths; And a control unit, which controls the light emission profile of the plurality of semiconductor light-emitting elements based on the image signal of the camera element, and drives the plurality of semiconductor light-emitting elements with a drive signal corresponding to the light emission profile; in, The control unit controls the light emission profiles of the plurality of semiconductor light-emitting elements to perform main light emission during the pseudo-global exposure of the imaging element, and to perform pre-light emission during at least a portion of the pixel readout periods of the imaging element that are different from the pseudo-global exposure period. The control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during the pixel reading of the final predetermined number of rows of pixels constituting the observed image of the subject. The emission level of the pre-emission emission is lower than the emission level of the main emission emission.

2. The light source device according to claim 1, wherein, The sum of the pre-light emission period × emission level is sufficiently less than the sum of the main light emission period × emission level and reaches a level where noise caused by the rolling shutter of the camera element can be ignored.

3. The light source device according to claim 1, wherein, The control unit controls the total value of the pre-light emission period × emission level to be less than 10% of the value of the main light emission period × emission level.

4. The light source device according to claim 1, wherein, The control unit controls the light emission profile so that the pre-emission is configured as continuous light or pulsed light throughout the entire period of the pixel reading.

5. The light source device according to claim 1, wherein, The control unit compares the metering value of one frame of the observed image of the subject with a first threshold and determines whether to change the luminous contour.

6. The light source device according to claim 5, wherein, When the photometric value is greater than the first threshold and there is excess light, the control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

7. The light source device according to claim 1, wherein, The control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during pixel reading of pixels in the lower 25% or less of the observed image of the subject.

8. The light source device according to claim 7, wherein, The control unit controls the total value of the pre-light emission period × emission level to be less than 10% of the value of the main light emission period × emission level.

9. The light source device according to claim 7, wherein, The control unit compares the metering value based on the pre-emission emission in one frame of the observed image of the subject with a second threshold, and determines whether to change the emission profile.

10. The light source device according to claim 9, wherein, When the photometric value is greater than the second threshold and there is excess light, the control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

11. An endoscope system for inserting an endoscope into an object of observation and acquiring images of the object, comprising: Multiple semiconductor light-emitting elements are used to emit light in different wavelengths; An imaging element for illuminating the subject with illumination light and detecting reflected light from the subject to generate an image signal; A processor for processing the image signal to generate an image of the subject and displaying it on a monitor; a main control unit for generating control signals based on the image signal to control the light emission profiles of the plurality of semiconductor light-emitting elements; And a light source control unit, which is used to receive the control signal from the main control unit and drive the plurality of semiconductor light-emitting elements with a drive signal corresponding to the light emission profile; in, The main control unit controls the light emission profiles of the plurality of semiconductor light-emitting elements to perform main light emission during the pseudo-global exposure of the imaging element, and to perform pre-light emission during at least a portion of the pixel readout periods of the imaging element that are different from the pseudo-global exposure period. The main control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during the pixel reading of the final predetermined number of rows of pixels constituting the observed image of the subject. The emission level of the pre-emission emission is lower than the emission level of the main emission emission.

12. The endoscopic system according to claim 11, wherein, The sum of the pre-light emission period × emission level is sufficiently less than the sum of the main light emission period × emission level and reaches a level where noise caused by the rolling shutter of the camera element can be ignored.

13. The endoscopic system according to claim 11, wherein, The main control unit controls the total value of the pre-light emission period × emission level to be below 10% of the value of the main light emission period × emission level.

14. The endoscope system according to claim 11, wherein, The main control unit controls the light emission profile so that the pre-emission configuration is continuous light or pulsed light throughout the entire period of the pixel reading period.

15. The endoscopic system according to claim 11, wherein, The main control unit compares the metering value of one frame of the observed image of the subject with a first threshold, and determines whether to change the luminous contour.

16. The endoscopic system according to claim 15, wherein, When the photometric value is greater than the first threshold and there is excess light, the main control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

17. The endoscopic system according to claim 11, wherein, The main control unit controls the light emission profile to perform the pre-emission of continuous light or pulsed light during pixel reading of pixels in the lower 25% or less of the observed image of the subject.

18. The endoscopic system according to claim 17, wherein, The main control unit controls the total value of the pre-light emission period × emission level to be below 10% of the value of the main light emission period × emission level.

19. The endoscopic system according to claim 17, wherein, The main control unit compares the photometric value based on the pre-emission emission in one frame of the observed image of the subject with the second threshold, and determines whether to change the emission profile.

20. The endoscopic system according to claim 19, wherein, When the photometric value is greater than the second threshold and there is excess light, the main control unit changes the light emission profile so that the light emission level of the main light emission gradually decreases in multiple frames.

Images