Light source device and electronic endoscope system

Abstract

To make it possible to timely detect a decrease in output of a light source device that generates light for illuminating a subject.SOLUTION: One aspect of the present invention is a light source module 30 that includes a substrate 300, an LED 31 that is arranged on the substrate 300 and emits illumination light for a subject, a photodetector 34 that is arranged on the substrate 300 and detects the illumination light emitted by the LED 31, and a control unit 21 that determines whether or not the LED 31 has deteriorated on the basis of the difference between the current detection value and the previous detection value of the amount of illumination light when the amount of illumination light is detected multiple times by the photodetector 34 under the same conditions. A slit 50 is formed in the substrate 300 as a through groove to suppress heat conduction from the LED 31 to the photodetector 34.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a light source device that generates light for irradiating a biological tissue.

Background Art

[0002] In the field of medical devices, an endoscope system capable of generating a suitable image for diagnosing a lesion hidden in a body cavity by illuminating a biological tissue in the body cavity and imaging the illuminated biological tissue in the body cavity as a subject is known. Conventionally, lamp light sources such as xenon lamps and halogen lamps that emit white light have been used as illumination light, but recently, light sources such as light emitting diodes (LEDs) that emit light in a specific wavelength band have been used instead of lamp light sources (for example, Patent Document 1).

[0003] Patent Document 1 describes an endoscope including an illumination unit including a plurality of LEDs. In this endoscope, a photometric value is derived by a photometric circuit based on imaging data (image signal) obtained by the imaging unit, and an automatic dimming control unit that controls the light amount of each LED based on the derived photometric value is provided.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the conventional lighting unit (i.e., light source device) described in Patent Document 1, automatic dimming control is performed based on the amount of reflected light from the subject incident on the imaging unit from the subject. Therefore, it is impossible to detect a decrease in output due to the secular deterioration of the light source itself. That is, just by observing the reflected light from the subject, it is impossible to determine whether the amount of reflected light has decreased due to the characteristics of the subject and / or the distance from the subject, or whether the amount of reflected light has decreased due to the deterioration of the light source itself.

[0006] Therefore, an object of the present invention is to enable timely detection of a decrease in output of a light source device that generates light for irradiating a subject.

Means for Solving the Problems

[0007] One aspect of the present disclosure is a substrate, a light emitting unit disposed on the substrate that emits illumination light toward a subject, a light detection unit disposed on the substrate that detects the illumination light emitted by the light emitting unit, a control unit that determines the presence or absence of deterioration of the light emitting unit based on a difference between a current detection value and a previous detection value of the amount of the illumination light when the light detection unit detects the amount of the illumination light a plurality of times under the same conditions. The light source device includes: A through groove is formed in the substrate so as to suppress heat conduction from the light emitting unit to the light detection unit.

[0008] The through groove may extend so as to cross a virtual line between the light emitting unit and the light detection unit when the substrate is viewed in a plan view.

[0009] The through groove may be formed in a U shape so as to surround three sides of the light emitting unit and / or the light detection unit when the substrate is viewed in a plan view.

[0010] When the control unit determines that there is no deterioration of the light emitting unit, the control unit may correct the light emission intensity of the light emitting unit based on a difference between a reference value and the current detection value of the illumination light detected by the light detection unit.

[0011] Another aspect of the present disclosure is the above-described light source device and, an endoscope having an imaging device and configured to acquire an imaging image of a biological tissue based on illumination light irradiated from the light source device onto the biological tissue, a processor configured to process the imaging image of the biological tissue acquired by the endoscope, and an electronic endoscope system including the same.

Advantages of the Invention

[0012] According to the above-described light source device, it is possible to timely detect a decrease in the output of the light source device that generates light for irradiating a subject.

Brief Description of the Drawings

[0013]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

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Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the electronic endoscope system according to the present embodiment will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing an example of the configuration of the electronic endoscope system 1 of the present embodiment. As shown in FIG. 1, the electronic endoscope system 1 is a system specialized for medical use, and includes an electronic scope (endoscope) 10, an endoscope processor 20 (hereinafter simply referred to as "processor 20") to which the electronic scope 10 is connected by a connector, and a monitor 40.

[0015] The processor 20 includes a control unit 21. The control unit 21 has a CPU that executes various programs stored in the memory 23, and integrally controls the entire electronic endoscope system 1. Further, the control unit 21 is connected to an operation panel 24. The control unit 21 changes each operation of the electronic endoscope system 1 and parameters for each operation according to an instruction from an operator input to the operation panel 24. The control unit 21 supplies a clock pulse serving as a reference for the timing of operations of each part in the electronic endoscope system 1 to each part in the system.

[0016] A light source module 30 is provided in the processor 20. The light source module 30 has a light emitting element (LED: Light Emitting Device) that emits illumination light for illuminating a subject such as a living tissue in a body cavity. When one LED is used, the LED is preferably a white LED. Although not shown, a plurality of LEDs may be provided. The plurality of LEDs each have a different wavelength band of emitted light. In one example, they include a UV LED, a blue LED, a green LED, an amber LED, and a red LED. The illumination light is white light or pseudo-white light obtained by synthesizing the emitted light of the plurality of LEDs. White light is light having a flat spectral intensity distribution in the visible light band, and pseudo-white light is light in which the spectral intensity distribution is not flat and light in a plurality of wavelength bands is mixed. The illumination light of the light source module 30 is condensed on the incident end face of the LCB (Light Carrying Bundle) 11 provided in the electronic scope 10 and enters the LCB 11. Further, the illumination light emitted from the exit end face of the LCB 11 is irradiated onto the subject through the light distribution lens 12. The return light from the subject illuminated by the illumination light from the light distribution lens 12 forms an optical image on the light receiving surface of the image sensor 14 through the objective lens 13.

[0017] In one embodiment, the light source module 30 is configured to be incorporable into the housing (not shown) of the processor 20. Calibration for each LED is performed during the manufacture of the light source module 30, and then the calibrated light source module 30 is incorporated into the processor 20. Further, when the light source module 30 fails or deteriorates over time, a new light source module 30 can be incorporated into the processor 20 after calibration. Note that in FIG. 1, an example in which the light source module is incorporated into the processor 20 is shown, but it is not limited thereto. The light source module may be incorporated into the electronic scope 10, or may be provided separately from the processor 20 and the electronic scope 10. In that case, the portion related to the light source control of the control unit 21 and the memory 23 described later may be incorporated into the light source module.

[0018] The image sensor 14 is an image sensor having a Bayer-type pixel arrangement. The image sensor 14 accumulates the optical image formed at each pixel on the light receiving surface as charges according to the amount of light, reads them out, and generates and outputs imaging data. Note that a CMOS image sensor, a CCD image sensor, or other types of imaging devices can be adopted as the image sensor 14. The image sensor 14 may also be equipped with a complementary color filter.

[0019] The electronic scope 10 includes a signal processing unit 15 in the connection part with the processor 20. The signal processing unit 15 performs a process of driving the image sensor 14 under the control of the control unit 21 and acquires imaging data from the image sensor 14. In one embodiment, the signal processing unit 15 supplies a synchronization signal (e.g., a vertical synchronization signal) for one frame to the image sensor 14, acquires imaging data of the subject from the image sensor 14 in frame units, and transmits it to the image processing unit 22 of the processor 20. The frame period is, for example, 1 / 30 second or 1 / 60 second. Note that the signal processing unit 15 is not limited to supplying a synchronization signal for one frame. Depending on the image sensor, it may transmit imaging data based on a synchronization signal created by itself. In that case, it is not necessary for the signal processing unit 15 to supply a synchronization signal for one frame to the image sensor.

[0020] After buffering the imaging data output from the signal processing unit 15 and performing predetermined image processing on the imaging data, the image processing unit 22 of the processor 20 generates a video format signal and outputs it to the monitor 40. Examples of image processing include demosaicing processing, matrix operation, edge enhancement processing, and the like.

[0021] Next, with reference to FIG. 2, the part related to light source control in the electronic endoscope system 1 of FIG. 1 will be described. FIG. 2 is a block diagram showing in more detail the part related to light source control of the electronic endoscope system 1. In FIG. 2, the light source module 30, the control unit 21, and the memory 23 constitute an example of a light source device.

[0022] Referring to FIG. 2, the light source module 30 includes an LED 31, a driver circuit 32, a photodetector 34, ADCs (Analogue to Digital Converters) 35, 37, and a thermistor 36. The control unit 21 has a CPU 25 and a gain adjustment unit 26. As described above, the light source module 30 includes one or more LEDs. Since the configuration for processing each LED is the same, hereinafter, one set of LEDs will be described. For example, in FIG. 2, the light source module 30 shows one set of driver circuits 32 and LEDs 31 for the analog dimming signal and the PWM dimming signal supplied from the control unit 21. When a plurality of LEDs are provided, a plurality of sets corresponding to the number of actually provided LEDs are provided in the light source module 30.

[0023] In general, PWM dimming and analog dimming are known as LED dimming methods. PWM dimming is a method of adjusting the illuminance of an LED by adjusting the duty ratio of a PWM signal, and analog dimming is a method of adjusting the illuminance of an LED by changing the amount of current supplied to the LED. Hereinafter, an example in the case where the LED is analog dimming will be described, but the case of PWM dimming can be applied in the same manner.

[0024] The memory 23 stores the light quantity data of the LED 31 measured at the time of factory shipment of the light source module 30 or at the first system startup after the light source module 30 is incorporated into the processor 20 (for example, the value of the light quantity detected by the photodetector 34 when a current of the reference current value flows through the LED 31 (referred to as the "reference light quantity value"). data). In addition, in the memory 23, at each startup of the system, the value of the light quantity detected by the photodetector 34 when a current of the above reference current value flows through the LED 31 and the detection value of the thermistor 36 described later are recorded. In one embodiment, instead of the value of the light quantity at each startup of the system, it may be the average value of the light quantity from the first system startup after the light source module 30 is incorporated into the processor 20, or the average value of the light quantity at a plurality of recent system startups. The variance of the light quantity for a plurality of times may be recorded.

[0025] When the processor 20 starts up, the CPU 25 generates and outputs an analog dimming signal IL indicating the value of the current flowing through the LED 31 of the light source module 30. The generated signal IL is a value corresponding to the required illuminance based on the operation input to the operation panel 24 or the automatic dimming control (not shown). Note that the generation and output of the signal IL may be executed by an ASIC, FPGA, etc. (not shown) instead of the CPU 25.

[0026] The gain adjustment unit 26 amplifies the signal IL supplied from the CPU 25 based on the gain indicated by the CPU 25, and outputs the amplified signal IL_OUT. Here, the CPU 25 determines the gain based on the difference between the light amount reference value stored in the memory 23 and the light amount of the illumination light of the LED 31 detected by the photodetector 34 (an example of the current detection value this time) when a current of the reference current value is passed through the LED 31 at the start of the system. For example, when the current detection value this time has decreased by 20% from the light amount reference value, the gain is determined to compensate for the 20% decrease. When calculating the difference, instead of the current light amount of the illumination light of the LED 31 detected by the photodetector 34, an average value of the current light amount and the detection values of the light amounts at a plurality of recent system startups may be used.

[0027] The driver circuit 32 drives the LED 31 based on the signal IL_OUT supplied from the control unit 21. The larger the value of the current indicated by the signal IL_OUT, the more the driver circuit 32 drives the LED 31 so that a larger current flows through the LED 31.

[0028] Note that the above correction shows an example of adjusting the gain based on a single reference current value, but it is not limited to this. Generally, since the relationship between the current and the light amount of an LED is non-linear, the light amounts of the illumination light of the LED 31 when currents of a plurality of different reference current values are passed through in advance are measured and recorded. At the start of the system, the light amount value of the LED 31 is measured by passing currents of a plurality of corresponding different reference current values, and the coefficients of the polynomial model indicating the relationship between the current value flowing through the LED 31 and the gain may be calculated.

[0029] The photodetector 34 is composed of, for example, a photodiode (PD), and outputs an electrical signal (analog signal) corresponding to the amount of light emitted from the LED 31. As will be described later, since the photodetector 34 is arranged in the vicinity of the LED 31, the amount of light emitted from the LED 31 can be accurately measured. The ADC 35 converts the electrical signal output from the photodetector 34 into a digital signal and sends it to the CPU 25.

[0030] In one embodiment, a thermistor 36 is installed in the light source module 30. The thermistor 36 measures the temperature of the LED 31, and is preferably arranged in the vicinity of the LED 31 on the substrate on which the LED 31 is mounted, but this is not the limit. Since it is only necessary to grasp the relative temperature change of the LED 31, it may be arranged at any position on the substrate on which the LED 31 is mounted. Generally, the characteristics of an LED are temperature-dependent (the light amount decreases as the temperature rises). Therefore, the detected temperature of the thermistor 36 when the light amount reference value is obtained is recorded, and when the difference from the detected temperature of the thermistor 36 when the light amount is obtained at the time of system startup (when correcting the LED 31) is equal to or less than a predetermined value, the correction of the LED 31 may be executed.

[0031] Next, with reference to the flowchart of FIG. 3, the startup process of the electronic endoscope system 1 will be described. When the power of the electronic endoscope system 1 is turned on, the control unit 21 supplies a current of a reference current value to the LED 31 and measures the light amount and temperature of the LED 31 (step S2). At this time, the CPU 25 generates a signal IL corresponding to the reference current value, and controls the gain adjustment unit 26 so as to output a signal IL_OUT without amplifying the signal IL. The output signal IL_OUT is supplied to the driver circuit 32 of the light source module 30. The amount of light of the illumination light emitted from the LED 31 based on the reference current value is detected by the photodetector 34, and the digital value thereof is supplied to the CPU 25. The CPU 25 stores (records) the light amount value of the LED 31 at the reference current value in the memory 23 (step S4).

[0032] The CPU 25 determines whether the light quantity value (the currently detected value) of the LED 31 at the reference current value is within the range where correction is unnecessary (step S6). Specifically, the CPU 25 compares the currently detected value with the light quantity reference value stored in the memory 23. If the difference between the two is equal to or less than a predetermined threshold value, it determines that the currently detected value is within the range where correction is unnecessary (step S6: YES), and ends the startup process.

[0033] On the other hand, if it is determined that the currently detected value is not within the range where correction is unnecessary, the CPU 25 determines whether the currently detected value is a value that requires correction but is not at an abnormal level, or whether it is at an abnormal level (step S8). In step S8, if the difference between the currently detected value and the light quantity reference value stored in the memory 23 is greater than a predetermined second threshold value set to a value larger than the threshold value used in step S6, it is determined that the currently detected value is at an abnormal level. For example, when the output characteristics of the LED 31 deteriorate significantly due to aging deterioration or damage caused by temperature, the currently detected value of the LED 31 becomes an abnormal level. If it is determined that the currently detected value is at an abnormal level (step S8: YES), the CPU 25 performs a predetermined warning output to the monitor 40 (step S10) and ends the startup process.

[0034] If it is determined that the currently detected value is not at an abnormal level (step S8: NO), the CPU 25 determines a gain based on the light quantity reference value so as to correct the output characteristics of the LED 31 (step S12) and ends the startup process. In this case, during the system operation after the startup process, the CPU 25 operates the gain adjustment unit 26 with the gain determined in step S12.

[0035] Next, with reference to FIGS. 4 and 5, the arrangement of the LED 31 and the photodetector 34 in the light source module 30 will be described. FIG. 4 shows a partial plan view of the substrate 300 of the light source module 30. FIG. 5 shows a cross-sectional view taken along line A-A of the plan view.

[0036] Even when the amount of light emitted by LED31 is small, in order to detect the light amount well and improve the accuracy of correction for LED31, it is necessary to place the photodetector 34 as close as possible to LED31. Also, placing the photodetector 34 as close as possible to LED31 contributes to reducing the space occupied by the light source module 30. On the other hand, when the photodetector 34 is placed close to LED31, the temperature of the photodetector 34 may increase due to the heat generated by LED31, and the photodetector 34 may be damaged, or the linearity of the photodetector 34 may decrease due to an increase in dark current or the like. Therefore, in the light source module 30, while the LED31 and the photodetector 34 are arranged close to each other on the same substrate, slits are formed as through-holes on the substrate 300 in order to suppress heat conduction from the LED31 to the photodetector 34.

[0037] In one embodiment, as shown in the plan view of FIG. 4, a slit 50 including a portion extending across the virtual line IM between the LED31 and the photodetector 34 is provided. By providing a through-hole in the portion extending across the virtual line IM, there is an effect of blocking the flow of heat directly from the LED31 to the photodetector 34. The slit 50 illustrated in FIG. 4 is preferably formed in a U-shape so as to surround three sides of the photodetector 34 as a whole. In this case, not only the heat directly from the LED31 to the photodetector 34 but also the heat from the side to the photodetector 34 can be blocked. That is, the heat transmitted from the LED31 through the substrate 300 can be blocked on three sides.

[0038] On the substrate 300, conductor patterns 41 and 42 extending from the two terminals of the photodetector 34 to the connectors 38 respectively are formed. The conductor patterns extending from each terminal of the LED31 are not shown in FIG. 4. Referring to the cross-sectional view taken along line A-A of FIG. 5, the LED 31 and the photodetector 34 are surface-mounted on the substrate 300. An insulating layer 43, a solder resist 44 or a conductive pattern 45, a solder paste 46, and pads 47 are formed on the substrate 300 in a stacked manner. Each terminal (electrode) of the LED 31 and the photodetector 34 is joined to the pad 47. These stacking and mounting methods can utilize known techniques and will not be described in detail. Note that the formation of the slit 50 is performed before joining the LED 31 and the photodetector 34 to the pad 47.

[0039] In the cross-sectional view taken along line A-A of FIG. 5, the portion of the slit 50 that crosses the virtual line IM in the plan view of FIG. 4 penetrates the substrate 300. Since the substrate 300 is often made of a conductor with high thermal conductivity such as copper or aluminum, by passing the substrate 300 through the slit 50, the heat conduction from the LED 31 to the photodetector 34 is significantly suppressed. Note that if the LED 31 and the photodetector 34 are arranged on two different substrates without providing the slit 50, although the heat conduction from the LED 31 to the photodetector 34 can be blocked, there is a possibility that the detection accuracy of the photodetector 34 may be affected by the arrangement variation of the two substrates, which is not preferable.

[0040] The form of the slit 50 shown in FIG. 4 is only an example, and other forms can also be adopted. FIGS. 6 to 8 show modified examples of the light source module. FIGS. 6 to 8 show slits 51 to 53 in forms different from FIG. 4, respectively. The slit 51 shown in FIG. 6 is common to the slit 50 in FIG. 4 in that it includes a portion extending across the virtual line IM between the LED 31 and the photodetector 34, but is different from the slit 50 in that it is formed in a U shape so as to surround three sides of the LED 31. Also in this case, the heat traveling from the LED 31 to the photodetector 34 can be blocked on three sides.

[0041] The slit 52 shown in FIG. 7 is common with the slit 50 in FIG. 4 in that it includes a portion extending across the virtual line IM between the LED 31 and the photodetector 34, but is different from the slit 50 in that it is formed in an I shape rather than a U shape as a whole. Also in this case, the heat transfer from the LED 31 toward the photodetector 34 is suppressed. The slit 52 is preferably made sufficiently long. The slit 53 shown in FIG. 8 is common with the slit 50 in FIG. 4 in that it includes a portion extending across the virtual line IM between the LED 31 and the photodetector 34, but is different from the slit 50 in that it is formed in an H shape as a whole so as to surround three sides of both the LED 31 and the photodetector 34. Also in this case, the heat from the LED 31 toward the photodetector 34 can be blocked on three sides.

[0042] As described above, in the light source module 30, the LED 31 that emits illumination light toward the subject and the photodetector 34 that detects the illumination light emitted by the LED 31 are mounted on the same substrate. When the control unit 21 detects the light amount of the illumination light a plurality of times by the photodetector 34 under the same conditions, it determines the presence or absence of deterioration of the LED 31 based on the difference between the current detected value and the previous detected value of the light amount of the illumination light. Since the photodetector 34 directly receives the emitted light of the LED 31 instead of the reflected light from the subject, it can detect the secular deterioration (for example, a decrease in light amount) of the LED 31 in a timely manner. Moreover, through grooves are formed in the substrate on which the LED 31 and the photodetector 34 are mounted so as to suppress the heat conduction from the LED 31 to the photodetector 34. Therefore, the photodetector 34 can be brought sufficiently close to the LED 31 without being adversely affected by heat. Therefore, even when the light amount of the illumination light of the LED 31 is small, the light amount can be detected well, and when correcting the LED 31 based on the detection value of the photodetector 34, the correction accuracy can be improved.

[0043] As described above, the light source device and the electronic endoscope system of the present invention have been described in detail. However, the light source device and the electronic endoscope system of the present invention are not limited to the above-described embodiments, and various improvements and modifications can of course be made without departing from the gist of the present invention.

Explanation of Symbols

[0044] 1…Electronic endoscope system 10…Electronic scope 11…LCB 12…Light distribution lens 13…Objective lens 14…Image sensor 15…Signal processing unit 20…Processor 21…Control unit 22…Image processing unit 23…Memory 24…Operation panel 25…CPU 26…Gain adjustment unit 30…Light source module 31…LED 32…Driver circuit 34…Photodetector 35,37…ADC 36…Thermistor 38…Connector 40…Monitor 41,42,45…Conductive pattern 43…Insulation layer 44…Soldermask 46…Solder paste 47…Pad 50,51,52,53…Slit 300…Substrate

Claims

1. A substrate, a light-emitting unit disposed on the substrate and emitting illumination light toward a subject, a light detection unit disposed on the substrate and detecting the illumination light emitted by the light-emitting unit, and a control unit that determines whether the light-emitting unit is deteriorated based on a difference between a current detection value and a previous detection value of the amount of the illumination light when the light detection unit detects the amount of the illumination light a plurality of times under the same conditions. The light source device is provided with a through groove formed in the substrate so as to suppress heat conduction from the light-emitting unit to the light detection unit. A light source device, wherein a through groove is formed in the substrate so as to suppress heat conduction from the light-emitting unit to the light detection unit.

2. The through groove extends so as to cross a virtual line between the light-emitting unit and the light detection unit when the substrate is viewed in a plan view. The light source device according to Claim 1.

3. The through groove is formed in a U shape so as to surround three sides of the light-emitting unit and / or the light detection unit when the substrate is viewed in a plan view. The light source device according to Claim 2.

4. When the control unit determines that the light-emitting unit is not deteriorated, the control unit corrects the light emission intensity of the light-emitting unit based on a difference between a reference value and the current detection value of the illumination light detected by the light detection unit. The light source device according to any one of Claims 1 to 3.

5. An electronic endoscope system, comprising: the light source device according to any one of Claims 1 to 4; an endoscope having an imaging device and acquiring an imaging image of a biological tissue based on illumination light irradiated from the light source device to the biological tissue; and a processor that processes the imaging image of the biological tissue acquired by the endoscope. An electronic endoscope system comprising the above components.

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