JP6240700B2 - Endoscope device - Google Patents

Description

  The present invention relates to an endoscope apparatus.

  2. Description of the Related Art Endoscopic devices that observe tissue in a body cavity are widely known. In general, an endoscope apparatus irradiates white light (irradiation light) emitted from a white light source such as a xenon lamp onto an observation area in a body cavity through a light guide, and an image based on reflected light from the observation area. Is received by an image sensor and an observation image is generated.

  Also, in recent years, special light such as narrow-band light observation for observing capillaries and fine structures on the tissue surface layer by irradiating a biological tissue with narrow-band light of a specific wavelength, or autofluorescence, fluorescence observation by drug fluorescence, etc. An endoscope apparatus having the observation mode used is also used. As the special light, a mixture of light from a white light source such as a xenon lamp and narrow band light from a semiconductor light source such as a laser diode is known (Patent Document 1).

  In the method described in Patent Document 1, since a xenon lamp is used as a white light source, it is difficult to finely control the emission light amount ratio between white light and narrowband light. Therefore, instead of a xenon lamp as a white light source, it is possible to use a light source that combines a light emitting diode (LED) with a long life and little output fluctuation and a phosphor. As described above, when two semiconductor light sources are used as the light sources during special light observation, the output of the semiconductor light sources can be finely controlled, so that the wavelength balance (emitted light quantity ratio) can be set with high accuracy.

  However, it is not easy to intensity-modulate each of the two semiconductor light sources while maintaining the wavelength balance with high accuracy. In particular, when using a light source having a region where the characteristic of the emitted light quantity with respect to the input current value is nonlinear, such as an LED, control in consideration of this nonlinearity is required.

JP 2009-201940 A

  The present invention has been made in view of the above circumstances, and an object of the present invention is an endoscope apparatus using two light sources including at least a semiconductor light source having a region in which a characteristic of an emitted light amount with respect to an input current value is nonlinear. When performing special light observation, the mixing ratio of light from these two light sources is kept constant with high accuracy so that a desired observation image can be acquired.

An endoscope apparatus according to the present invention is an endoscope apparatus that irradiates a subject with illumination light from the tip of an endoscope insertion portion, receives reflected light from the subject, and obtains an image signal of the subject. In addition, the observation mode selection unit that switches the observation mode including the normal observation mode and the narrow-band light observation mode, the endoscope having the image pickup device that images the subject, and the light emission intensity characteristic with respect to the drive current value are nonlinear. A white light source that emits white light using a light emitting diode having a region, and a narrow band light source that emits light in a narrower wavelength range than the white light source, and the amount of light emitted from the white light source and the narrow band light source When the observation mode selected by the observation mode selection unit is a narrow-band light observation mode, the ratio of the amount of light emitted from the white light source and the narrow-band light source is controlled, and the white light source and the narrow-band light source The total amount of emitted light And a control device that emits light only from the white light source when the observation mode selected by the observation mode selection unit is a normal observation mode, and the control device has the set light amount Is the range from the maximum value to the threshold value, the first drive current value supplied to the white light source and the second drive current value supplied to the narrowband light source are set regardless of the set light amount. Each of the white light source and the narrow-band light source is set to a constant value according to a ratio of emitted light, and the current based on the first driving current value set to the constant value is set to the white light source. By supplying a current based on the second drive current value set to the constant value for a time corresponding to the set light amount, and driving the white light source and the narrowband light source, White light Wherein the quantity of light emitted from and controls a constant light quantity ratio of the amount of light emitted from the narrowband light source.

  According to the present invention, when performing special light observation with an endoscope apparatus using two light sources including at least a semiconductor light source having a region in which the characteristic of the emitted light quantity with respect to the input current value is nonlinear, the two light sources It is possible to obtain a desired observation image while keeping the light mixing ratio constant with high accuracy.

1 is an external view of an endoscope apparatus 100 for explaining an embodiment of the present invention. The figure which shows the internal structure of the endoscope apparatus 100 shown by FIG. The figure which shows the relationship between the wavelength of the light radiate | emitted from light source K1, K2, and emitted light intensity. The figure which shows the relationship between the amplitude value of the drive pulse supplied to light source K1, K2, and the emitted light quantity of light source K1, K2. The figure which shows an example of the drive signal common to the light sources K1 and K2 which the light source control part 49 produces | generates

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

  FIG. 1 is an external view of an endoscope apparatus 100 for explaining an embodiment of the present invention.

  The endoscope apparatus 100 includes an endoscope 11, a control device 13, a display unit 15 such as a liquid crystal display device, and an input unit 17 such as a keyboard and a mouse for inputting information to the control device 13.

  The control device 13 includes a light source device 45 and a processor 47 that performs signal processing of a captured image signal output from the endoscope 11.

  The endoscope 11 includes an endoscope insertion portion 19 that is inserted into a subject, an operation portion 23 that performs an operation for bending and observing the distal end of the endoscope insertion portion 19, and the endoscope 11. Connector portions 25 and 27 are detachably connected to the control device 13.

  The endoscope insertion portion 19 includes a flexible soft portion 29, a bending portion 31, and a distal end portion (hereinafter also referred to as an endoscope distal end portion) 33.

  Although not shown, various channels such as a forceps channel for inserting a tissue collection treatment instrument and the like, a channel for air supply / water supply, and the like are provided inside the operation unit 23 and the endoscope insertion unit 19. .

  FIG. 2 is a diagram showing an internal configuration of the endoscope apparatus 100 shown in FIG.

  The endoscope distal end portion 33 includes an illumination window 35 for irradiating light to an observation region, a diffusion plate 58 disposed opposite to the illumination window 35, and an illumination disposed between the diffusion plate 58 and the illumination window 35. Lens 59, imaging element 21 such as a CCD (Charge Coupled Device) image sensor or CMOS (Complementary Metal-Oxide Semiconductor) image sensor that receives reflected light from the observation region, and a light receiving surface of imaging element 21. An observation window 40 for allowing reflected light from the observation region to enter, and an objective lens unit 39 provided between the observation window 40 and the image sensor 21 are provided.

  The bending portion 31 is provided between the soft portion 29 and the distal end portion 33, and can be bent by a turning operation of an angle knob 43 (see FIG. 1) disposed in the operation portion 23.

  The bending portion 31 can be bent in an arbitrary direction and an arbitrary angle according to a part of the subject in which the endoscope 11 is used, and the illumination window 35 and the observation window of the endoscope distal end portion 33. 40 can be directed to the desired viewing site.

  The control device 13 includes a light source device 45 that generates illumination light supplied to the observation region from the illumination window 35 of the endoscope distal end portion 33, and red (R), green (G), And a processor 47 that processes a blue (B) captured image signal. The light source device 45 and the processor 47 are connected to the endoscope 11 via connector portions 25 and 27, respectively.

  The light source device 45 includes a light source controller 49, a light source K1 that emits white light using an LED as a light source, a light source K2 that emits narrowband light having a center wavelength of 405 nm, an optical fiber bundle 51, and an optical fiber 53. With.

  The light source K1 is a light source for normal observation (white light observation). The light source K1 is composed of an LED and a phosphor covering the LED. In the present embodiment, the light source K1 includes an LED that emits blue light having a wavelength of 445 nm and a YAG-based phosphor that emits yellow fluorescence using light emitted from the LED as excitation light. The yellow light excited by a part of the blue light emitted from the LED and the blue light transmitted through the phosphor are combined to emit white light from the light source K1. Since the light source K1 includes an LED, as shown in FIG. 4 to be described later, the light source K1 has a region where the characteristic of the emitted light quantity with respect to the amplitude value (input current value) of the drive signal is nonlinear.

  The light source K2 is a light source for narrow-band light observation and is made of a semiconductor element. As the light source K2, a laser diode in which the characteristic of the emitted light quantity with respect to the amplitude value of the drive signal is linear, or an LED having a region in which the characteristic of the emitted light quantity with respect to the amplitude value of the drive signal is nonlinear can be used. An example is a violet-emitting semiconductor laser having a central wavelength of 405 nm. As the laser light source, for example, a broad area type InGaN laser diode can be used. The light source K2 can perform good narrow-band light observation in which capillaries and fine structures on the mucosal surface layer are emphasized when the center wavelength of the emitted light is in the range of 370 to 470 nm.

  The light emitted from each of the light sources K1 and K2 is individually controlled by the light source control unit 49. The light source control unit 49 emits light only from the light source K1 in the normal observation mode. The light source control unit 49 emits light only from the light source K2 in the fluorescence observation mode. Further, the light source control unit 49 simultaneously emits light from the light sources K1 and K2 at a predetermined emission light amount ratio in the narrow-band light observation mode in which capillaries and fine structures on the tissue surface layer are observed.

  FIG. 3 is a diagram showing the relationship between the wavelength of light emitted from the light sources K1 and K2 and the emission intensity. In FIG. 3, symbol S1 indicates light emitted from the light source K1, and symbol S2 indicates light emitted from the light source K2. As shown in FIG. 3, the light from the light source K2 has almost no intensity in the wavelength range of 445 nm or more. Therefore, it is possible to control the ratio of the emitted light amounts of the light sources K1 and K2 with high accuracy. In addition, fluctuations in the intensity of light from the light source K2 do not substantially affect the white light from the light source K1. As a result, the image quality at the time of narrow band light observation can be improved.

  White light emitted from the light source K1 is input to the optical fiber bundle 51 by a condenser lens (not shown). Purple light emitted from the light source K2 is input to the optical fiber 53 by a condenser lens (not shown). The optical fiber bundle 51 and the optical fiber 53 are bundled together by a light guide 55, and the light guide 55 extends to the endoscope distal end portion 33 through the connector 25. The light emitted from the end face of the light guide 55 on the endoscope distal end 33 side is diffused by the diffusion plate 58 and then emitted from the observation window 35 through the lens 59.

  The light source controller 49 controls the light sources K1 and K2 by pulse driving. That is, the light source control unit 49 supplies a drive signal (a drive pulse pattern) to the light sources K1 and K2. The light sources K1 and K2 emit light during the period when the drive pulse is at a high level.

  The display unit 15 and the input unit 17 are connected to the processor 47. The processor 47 includes a signal processing unit 66, a control unit 69, and a storage unit 71.

  The signal processing unit 66 performs signal processing on the captured image signal transmitted from the endoscope 11 according to an instruction from the operation unit 23 or the input unit 17 of the endoscope 11 to generate captured image data. In addition, the signal processing unit 66 calculates luminance information (brightness information of the subject image) of the captured image signal from the captured image signal transmitted from the endoscope 11, and sends the luminance information to the control unit 69. Output. The captured image data generated in the signal processing unit 66 is reproduced on the display unit 15 or stored in the storage unit 71 under the control of the control unit 69.

  The storage unit 71 stores a luminance-target light amount table in which the luminance information of the captured image signal is associated with the target light amount value for one frame of light emitted from the light source device 45.

  In addition, the storage unit 71 outputs an amplitude value (drive current value) of a drive pulse constituting a drive signal supplied to the LED of the light source K1 and an emitted light amount per unit time of the light source K1 (one drive pulse is emitted). The light source K1 table associated with the light amount, the amplitude value (drive current value) of the drive pulse constituting the drive signal supplied to the light source K2, and the emitted light amount per unit time of the light source K2 (with one drive pulse). And a table for the light source K2 in which the amount of light emitted is associated with each other. As shown in FIG. 4, the relationship between the drive current of the light source K1 and the amount of emitted light is linear up to a certain drive current, but is nonlinear after the drive current is exceeded. Further, the relationship between the drive current of the light source K2 and the amount of emitted light is linear in all regions.

  The control unit 69 obtains a target light amount corresponding to the luminance information from the luminance information input from the signal processing unit 66 and the luminance-target light amount table stored in the storage unit 71, and obtains information on the target light amount. It transmits to the light source control part 49.

  The light source control unit 49 receives the information on the target light amount received from the control unit 69 and the ratio of the emitted light amount per one driving pulse of the light source K1 and the light source K2 set by the control unit 69 during the narrow-band light observation (emitted light intensity). Ratio) and the light source K1 table and the light source K2 table stored in the storage unit 71, while maintaining the emission light amount ratio per drive pulse of the light source K1 and the light source K2 at a set value, the light source K1 , K2 generates a drive signal such that the total amount of emitted light in one frame becomes the target amount of light, and supplies this drive signal to each of the light sources K1, K2.

  Hereinafter, the operation of the endoscope apparatus 100 in the narrow-band light observation mode will be described.

  First, when an operator presses an observation mode switching button 73 (see FIG. 2) that is provided in the endoscope 11 and functions as an observation mode selection unit, the control unit 69 performs normal observation, narrow-band light observation, fluorescence Control to switch to various observation modes such as observation is performed. In the normal observation mode, the control unit 69 sets the emitted light amount ratio Ra: Rb of the light sources K1, K2 to 1: 0. In the narrow-band light observation mode, the control unit 69 sets the outgoing light amount ratio Ra: Rb to an arbitrary preset ratio such as 2: 1. In the fluorescence observation mode, the control unit 69 sets the emission light amount ratio Ra: Rb to 0: 1.

  In the narrow-band light observation mode, the light source controller 49 controls the total light output from the light sources K1 and K2 to be the target light amount while maintaining the outputs of both the light sources K1 and K2 at the above-described light output ratio. . Hereinafter, a procedure for generating desired illumination light by driving the light sources K1 and K2 in the narrow-band light observation mode will be described.

  First, the control unit 69 reads the emission light amount ratio Ra: Rb (hereinafter, Ra = 2, Rb = 1) of the light source L1 and the light source L2 corresponding to the narrow-band light observation mode from the storage unit 71, It transmits to the control part 49. The light source control unit 49 that has received the information on the emitted light quantity ratio Ra: Rb sets the emitted light quantity ratio Ra: Rb as the designated emitted light quantity ratio.

  When the captured image signal is input to the signal processing unit 66, the signal processing unit 66 generates luminance information from the captured image signal. The control unit 69 sets a target light amount based on the luminance information and the luminance-target light amount table stored in the storage unit 71, and transmits information on the target light amount to the light source control unit 49.

  Next, the light source control unit 49 receives the information of the emission light amount ratio 2: 1 received from the control unit 69, the light source K1 table and the light source K2 table stored in the storage unit 71, and the control unit 69. Based on the information on the target light quantity, the amplitude value (drive current value) of the drive pulse constituting each drive signal supplied to the light sources K1 and K2 is set.

  Specifically, when the target light amount is equal to or greater than the threshold value, the light source control unit 49 determines a predetermined reference value (for example, the amplitude value of the light source K1 is the amplitude value of each drive pulse supplied to the light sources K1 and K2). Set to the maximum amplitude value combination). When the target light amount is less than the threshold, the light source control unit 49 sets the amplitude value of each drive pulse supplied to the light sources K1 and K2 to a value corresponding to the target light amount.

  For example, as shown in FIG. 4, when the target light amount is equal to or larger than the threshold value, the light source control unit 49 sets the amplitude value of the drive pulse supplied to the light source K1 to the maximum value i3a, and the amplitude value i3a The amplitude value i3b when the light amount half of the emitted light amount is obtained is set as the amplitude value of the drive pulse supplied to the light source K2. On the other hand, when the target light amount is less than the threshold, the light source control unit 49 sets the amplitude value of each drive pulse supplied to the light sources K1 and K2 as the target light amount decreases.

  The light source control unit 49 ensures that (whatever the target light amount is), (the emitted light amount per unit time of the light source K1) :( the emitted light amount per unit time of the light source K2) is always 2: 1. The amplitude value of each drive pulse supplied to the light sources K1, K2 is set.

  For example, when the target light amount is a predetermined value smaller than the threshold value, the light source control unit 49 sets the amplitude value of the drive pulse supplied to the light source K1 to i2a as shown in FIG. 4, and the amplitude value is i2a. The amplitude value i2b when the light amount half of the emitted light amount is obtained is set as the amplitude value of the drive pulse supplied to the light source K2. When the target light amount is a value smaller than the predetermined value, the light source control unit 49 sets the amplitude value of the drive pulse supplied to the light source K1 to i1a, and is half the emitted light amount at the amplitude value i1a. Is set as the amplitude value of the drive pulse supplied to the light source K2.

  Next, when the target light amount is equal to or greater than the threshold value, the light source control unit 49 generates a drive signal (drive pulse pattern) common to the light sources K1 and K2 according to the target light amount. Then, the light source controller 49 generates a drive signal for the light source K1 by changing the amplitude value of each drive pulse constituting the drive signal common to the light sources K1 and K2 to a value set for the light source K1. The drive signal for the light source K2 is generated by changing the amplitude value of each drive pulse constituting the drive signal common to the light sources K1 and K2 to a value set for the light source K2.

The light source control unit 49 has a design upper limit value that allows the target light amount to be emitted from the light source device 45 (when the amplitude value of the drive pulse supplied to the light sources K1 and K2 is a reference value). In the range from the value of 1 to the second value smaller than the first value, the total number of emitted light amounts is equal to the target light amount by pulse number control (PNM: Pulse Number Modulation) that changes the number of drive pulses included in the drive signal. The drive signals for the light sources K1 and K2 are generated.

  In addition, the light source control unit 49 generates a drive signal in which the number of drive pulses is reduced to the limit by the pulse number control in a range from the second value to the threshold value that is smaller than the second value. On the other hand, pulse density control (PDM: Pulse Density Modulation) for changing the density of the drive pulse is performed to generate drive signals for the light sources K1 and K2 such that the total emitted light quantity becomes the target light quantity.

  FIG. 5 is a diagram illustrating an example of drive signals common to the light sources K1 and K2 generated by the light source control unit 49.

  When the target light amount is the design upper limit of the total emitted light amount that can be emitted from the light source device 45, the light source control unit 49 is controlled by the electronic shutter within the period of one frame of the image defined by the vertical synchronization signal VD. A drive signal [1] composed of a drive pulse pattern for lighting all the exposure periods W to be generated is generated.

  When the target light amount decreases from the above design upper limit, the light source control unit 49 generates a drive signal in which the number of drive pulses is reduced by shifting the drive signal [1] back to the time axis. The drive signal [2] shown in FIG. 5 shows a signal obtained when the number of drive pulses is decreased with respect to the drive signal [1] so that the supply start timing of the drive pulses is delayed until a predetermined minimum ratio is reached. ing. The light source control unit 49 increases the decrease in the number of drive pulses with respect to the drive signal [1] as the target light amount decreases.

  When the target light quantity further decreases after the lighting time of the light source determined by the decrease in the number of drive pulses reaches the PNM control limit (Wmin in FIG. 5), the light source control unit 49 applies the drive pulse to the drive signal [2]. A drive signal [3] obtained by thinning out is generated. The light source controller 49 increases the thinning rate of the drive pulse for the drive signal [2] as the target light amount decreases.

  The drive pulse [4] in FIG. 5 is when the drive pulse interval in the drive signal generated in common for the light sources K1 and K2 reaches the PDM control limit. When the target light amount is the threshold value, the light source control unit 49 changes the amplitude value of each drive pulse of the drive signal [4] to the reference value of the amplitude value set for the light sources K1 and K2. The generated drive signal is generated. That is, the total amount of emitted light emitted from the light source device 45 in accordance with this drive signal is set as the above-described target light amount threshold.

  When the target light quantity becomes smaller than the above threshold value, the pulse light modulation control has already reached the limit, so that the target light quantity cannot be achieved. Therefore, in such a case, the light source control unit 49 sets the amplitude value (reference value) of the drive pulse set for each of the light sources K1 and K2 to a value that is decreased according to the target light amount.

  For example, when the amplitude values (reference values) of the drive pulses set for the light sources K1 and K2 when the target light amount is equal to or greater than the threshold value are i3a and i3b shown in FIG. 71, while maintaining the output light amount ratio at the set value based on the light source K1 table and the light source K2 table stored in 71, information on the target light amount, and the output light amount ratio determined according to the observation mode. The amplitude value (for example, i2a, i2b) of each drive pulse supplied to the light sources K1, K2 is calculated so that the total emitted light amount becomes the target light amount, and this amplitude value is calculated for each drive pulse supplied to the light sources K1, K2. Set as an amplitude value.

  The number of drive pulses included in the drive signal [4] is already known, and the amounts of light emitted from the light sources K1 and K2 with respect to the amplitude value of the drive pulse are known from the light source K1 table and the light source K2 table. For this reason, the light source control unit 49 can calculate how much the amplitude value can be reduced to achieve the target light amount based on such information.

  Then, the light source control unit 49 generates a drive signal for the light source K1 in which the amplitude value of each drive pulse of the drive signal [4] shown in FIG. 5 is i2a and each drive pulse of the drive signal [4] shown in FIG. A drive signal for the light source K2 having an amplitude value i2b is generated. The light source controller 49 supplies these two drive signals to the light sources K1 and K2, respectively. Thereby, even when the target light amount becomes less than the threshold value, the total emitted light amount is controlled to be the target light amount while the emitted light amount ratio is maintained at 2: 1.

  As described above, the light source control unit 49 generates a drive signal corresponding to the target light amount in common between the light sources K1 and K2, and based on this common drive signal, the drive signal for the light source K1 and the light source K2 The drive signal is generated by changing the amplitude value. When the target light amount changes between the set upper limit value of the total emitted light amount that can be emitted from the light source device 45 and the threshold value, the amplitude value of each drive signal remains fixed, and the waveform pattern of each drive signal is common. Changed. Thereby, even if the pulse modulation control is performed according to the change of the target light amount, the emitted light amount ratio remains fixed, and the light amount ratio emitted from each of the light sources K1 and K2 is not disturbed. When the target light amount becomes less than the threshold value, the waveform pattern of each drive signal is fixed, and only the amplitude value of each drive signal is changed according to the target light amount while maintaining the output light amount ratio. Thereby, even when the target light amount is reduced to the limit of the pulse modulation control, the total emitted light amount can be matched with the target light amount, and the light amount ratio emitted from each of the light sources K1 and K2 can be made constant. .

  In the endoscope apparatus 100, the light source control unit 49 sets the amplitude value of the drive pulse supplied to the light sources K1 and K2, using the light source K1 table and the light source K2 table stored in the storage unit 71. To do. For this reason, even if it is the structure of this embodiment which employ | adopted LED with the area | region where the characteristic of an emitted light quantity becomes nonlinear, control of the emitted light quantity ratio of the light sources K1 and K2 can be performed accurately.

  Further, the endoscope apparatus 100 has a configuration in which a drive signal corresponding to the target light amount is commonly used for the light sources K1 and K2. For this reason, the modulation control can be simplified as compared with the case where each drive signal for the light sources K1 and K2 is separately subjected to pulse modulation control. Furthermore, even when a plurality of light sources are provided, the pulse modulation control for the target light quantity ratio of each light source can be made common to all the light sources, and it is possible to prevent the drive circuit from becoming complicated.

  In the endoscope apparatus 100, when the target light amount is equal to or larger than the threshold value, the amplitude value of the light source K1 is set to a maximum value that can be set. The LED used for the light source K1 has a greater color variation as the amplitude value (drive current value) increases. When the target light amount is greater than or equal to the threshold value, it is a bright shooting environment, so that color variations are easily noticeable. Therefore, when the target light quantity is equal to or larger than the threshold value, it is preferable to set the amplitude value of the light source K1 to the maximum value that can be set in order to prevent image quality deterioration due to color variation. In the endoscope apparatus 100, when the target light amount is less than the threshold value, the amplitude value of the light source K1 is decreased from the maximum value. In this case, the subject is dark and the color variation is not noticeable. The impact of is limited.

  In the endoscope apparatus 100, the light source K1 may be provided not at the light source apparatus 45 but at the endoscope distal end portion 33. In this case, a configuration in which the light source K1 is replaced with another type using an adapter or the like is also conceivable. When the light source K1 is replaced with another type, the light source control unit 49 can perform the above-described control only by rewriting the light source K1 table stored in the storage unit 71 with new data.

  In the above description, the light source K1 emits white light and the light source K2 emits narrowband light. However, the light source K1 and the light source K2 may emit light in different wavelength ranges, and may be emitted. The wavelength range of the light to be transmitted is not limited to the combination of white light and narrow band light.

  In the above description, the light source K1 is a light emitting characteristic having a non-linear region (LED + phosphor) and the light source K2 is a linear light emitting characteristic (LD). However, the present invention is not limited to this. Each of the light sources K1 and K2 may have a non-linear region as light emission characteristics (for example, a combination of a light source made of LED + phosphor and a light source made of LED).

  As described above, the following items are disclosed in this specification.

  The disclosed endoscope apparatus is an endoscope apparatus that irradiates a subject with illumination light from the tip of an endoscope insertion portion, detects reflected light from the subject, and obtains an image signal of the subject. A first light source including a semiconductor light source having a region in which a characteristic of light emission intensity with respect to an amplitude value of the drive signal is nonlinear, and a semiconductor light source configured to emit light having a wavelength region different from that of the first light source. Two light sources, a target light amount setting unit for setting a target light amount with respect to a total emitted light amount obtained by summing the emitted light amounts from each of the first light source and the second light source, the first light source, and the second light source. A light amount ratio setting unit that sets the output light amount ratio of each of the light sources, and an information storage unit that stores information indicating the relationship between the amplitude values of the drive signals of each of the first light source and the second light source and the emitted light amount And the output light amount ratio set by the light amount ratio setting unit, A first amplitude value of a drive signal supplied to the first light source based on the information stored in the information storage unit and the target light amount set by the target light amount setting unit; and the second An amplitude value setting unit for setting a second amplitude value of a drive signal supplied to the light source; and a common drive signal for the first light source and the second light source based on the target light amount, A drive signal for the first light source is generated by changing an amplitude value of the drive signal to the first amplitude value, and an amplitude value of the common drive signal is changed to the second amplitude value. A drive signal generator for generating a drive signal for the second light source, supplying the drive signal for the first light source to the first light source, and supplying the drive signal for the second light source to the second light source And a signal supply unit that controls the total emitted light amount to be the target light amount. It is intended.

  The disclosed endoscope apparatus includes an imaging unit that images an object by adjusting an exposure period using an electronic shutter, and the drive signal generation unit is configured such that the target light amount ranges from a maximum value of the total emitted light amount to a threshold value. In the range, with respect to the exposure period within one frame by the electronic shutter, the first pulse modulation control for reducing the number of drive pulses included in the drive signal until the predetermined lighting period is reached, and the first pulse modulation The common drive signal is obtained by performing second pulse modulation control for reducing the drive pulse density by thinning out the drive pulses with respect to the drive signal whose number of drive pulses has been reduced to the limit by the control in order of increasing target light quantity. In the range where the target light amount is less than the threshold value, a drive signal whose drive pulse density has been reduced to the limit by the second pulse modulation control is transmitted to the common drive. The amplitude value setting unit sets an amplitude value predetermined in the information as the first amplitude value when the target light amount is in a range from the maximum value to the threshold value, The second amplitude value is set to an amplitude value at which an emitted light amount is obtained such that a ratio of a light amount emitted from the first light source to a light amount ratio set by the light amount ratio setting unit is In the range where the target light amount is less than the threshold value, the first amplitude value and the second amplitude value are set according to the magnitude of the target light amount.

  In the disclosed endoscope apparatus, the predetermined amplitude value includes the maximum amplitude value in the information about the first light source.

  The disclosed endoscope apparatus includes an observation mode selection unit that selects any one of the observation modes from a plurality of observation modes with different emphasis targets in the observation image acquired by the imaging unit, and the light amount ratio setting unit However, the emission light amount ratio is set in accordance with the selected observation mode.

  The disclosed endoscope apparatus includes a luminance information generation unit that generates luminance information of a subject image based on an imaging signal output from the imaging unit, and the target light amount setting unit is based on the luminance information. The target light quantity is set.

  In the disclosed endoscope apparatus, the first light source includes a light emitting diode and a phosphor, and the second light source includes a laser diode or a light emitting diode.

K1 White light source K2 Narrow band light source 49 Light source control unit 71 Storage unit

Claims (7)

An endoscope apparatus that irradiates a subject with illumination light from the tip of an endoscope insertion portion, receives reflected light from the subject, and obtains an image signal of the subject,
An observation mode selection unit for switching an observation mode including a normal observation mode and a narrow-band light observation mode;
An endoscope having an image sensor for imaging a subject;
A white light source that emits white light using a light emitting diode having a region in which light emission intensity characteristics with respect to a drive current value are nonlinear, and a narrowband light source that emits light in a narrower wavelength range than the white light source, When the amount of light emitted from the white light source and the narrow-band light source is set, and the observation mode selected by the observation mode selection unit is a narrow-band light observation mode, the ratio of the amount of light emitted from the white light source and the narrow-band light source is Control and control the total emitted light amount of the white light source and the narrow-band light source to a target light amount, and emit only from the white light source when the observation mode selected by the observation mode selection unit is the normal observation mode A control device,
The controller is
When the set light amount is in the range from the maximum value to the threshold value,
The first drive current value supplied to the white light source and the second drive current value supplied to the narrow band light source are emitted from the white light source and the narrow band light source , respectively , regardless of the set light amount. A second drive current set to a constant value according to the light amount ratio, a current based on the first drive current value set to the constant value for the white light source, and a constant value for the narrowband light source A current based on the value is supplied for a time corresponding to the set light amount, and the white light source and the narrow-band light source are driven, whereby the emitted light amount from the white light source and the narrow-band light source are An endoscope apparatus that controls the ratio of the quantity of emitted light to be constant. The endoscope apparatus according to claim 1,
The control apparatus includes a luminance information generation unit that generates luminance information of a subject image based on a captured image signal output from the imaging element, and based on the luminance information, the white light source and the narrowband light source An endoscope apparatus for setting the amount of emitted light. The endoscope apparatus according to claim 1 or 2,
The white light source includes a phosphor,
The narrow band light source is an endoscope apparatus configured by a laser diode or a light emitting diode. The endoscope apparatus according to claim 3, wherein
The narrow band light source is an endoscope apparatus configured by a light emitting diode. The endoscope apparatus according to claim 3 or 4,
An endoscope apparatus in which light from the narrow-band light source has almost no intensity at the excitation wavelength of the phosphor. The endoscope apparatus according to any one of claims 1 to 5,
The narrow band light source is an endoscope apparatus including a semiconductor light source in which a center wavelength of emitted light is included in a range of 370 to 470 nm. The endoscope apparatus according to any one of claims 1 to 6,
The said control apparatus is an endoscope apparatus which carries out the pulse drive of the said white light source and the said narrow-band light source.

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