JP6180612B2 - 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 supplies white light emitted from a white light source such as a xenon lamp as illumination light to a region to be observed in a body cavity through a light guide, and from the region to be observed by irradiation of the white light. An image based on the reflected light is picked up by an image pickup device 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 a light source for an endoscope device that emits special light, light from a white light source such as a xenon lamp is selectively extracted through a rotary filter having a predetermined light absorption characteristic. A configuration for irradiating a subject is known (see Patent Document 1). In the endoscope apparatus having the above-described configuration, B light and G light having a narrow band wavelength can be irradiated at a predetermined emission light amount ratio as special light for narrow band light observation. The intensity of the special light in this case is adjusted by a diaphragm device provided in the middle of the optical path from the white light source, and the emission ratio of G light to G light is the light transmittance of the B filter and G filter of the rotary filter. Is set.

JP 2006-218283 A

  However, since the intensity of the output light from the light source generally decreases due to deterioration with time, the ratio of the emitted light quantity of B light and G light specified by the transmittance of the rotary filter changes, and the wavelength balance of the emitted light is lost. There is. The wavelength balance of the emitted light affects the degree of projection of the feature amount component in the observation image. If the emitted light deviates from the desired wavelength balance, the feature amount may not be sufficiently observed.

Therefore, instead of a white light source such as a xenon lamp, it is possible to use a semiconductor light source including a laser light source having a long lifetime and little output fluctuation, and a semiconductor light emitting element such as a light emitting diode. In this case, the output of the semiconductor light source can be finely controlled, and the wavelength balance can be set with high accuracy. However, when intensity modulation is performed, it is difficult to intensity-modulate each of the plurality of types of semiconductor light sources while maintaining wavelength balance with high accuracy. For example, the amount of light can be controlled with high accuracy using a narrow pulse generator or a high-resolution PWM controller, but all of these devices are expensive and it is not practical to install them in an endoscope apparatus. .
As described above, there are still many problems in controlling the amount of light of a semiconductor light source as much as or more than that of a white light source such as a xenon lamp.

An object of the present invention is to provide an endoscope apparatus that can be controlled to a target light amount with high accuracy without breaking the balance of the emitted light amount ratios of a plurality of semiconductor light sources.

The present invention has the following configuration.
An endoscope apparatus having imaging means for generating illumination light using light emitted from a plurality of semiconductor light sources that emit light having different spectra and imaging reflected light from a subject by the illumination light,
A target light amount setting means for setting a target amount of the total amount of emitted light which is the sum of the amount of light emitted from the plurality of semiconductor light sources,
A light amount ratio setting means for setting an output light amount ratio of the plurality of semiconductor light sources;
An amplitude value setting means for setting the amplitude value of the driving signal to the plurality of semiconductor light sources based on the set light emission amount ratio,
In the narrow-band light observation mode, pulse modulation is performed in accordance with the target light amount set by the target light amount setting unit, and a driving pulse that is synchronized with an exposure period of the imaging unit is generated to drive the plurality of semiconductor light sources A single light source control means;
With
The semiconductor light source includes a white light source for generating white light, and a narrow band light source for generating narrow band light having a predetermined wavelength range,
The said light source control means is an endoscope apparatus which lights both the said light source for white light, and the said light source for narrow-band light in the same said exposure period.

According to the endoscope apparatus of the present invention, the target light quantity can be controlled with high accuracy without breaking the balance of the emitted light quantity ratios of the plurality of semiconductor light sources. Thereby, the illumination light of the endoscope in normal observation or special light observation can be accurately set to an arbitrary intensity while maintaining a desired emission light amount ratio.

It is a figure for describing an embodiment of the present invention, and is a lineblock diagram of an endoscope apparatus showing each apparatus to which an endoscope and an endoscope are connected. It is an external view which shows the specific structural example of an endoscope apparatus. It is a graph which shows the spectral characteristic of emitted light. It is explanatory drawing which shows the result of having calculated | required the contrast (luminance ratio) of the blood vessel and mucous membrane according to the emitted light quantity ratio of each laser light source. It is a graph which shows the relationship with the emitted light quantity with respect to target light quantity when the emitted light quantity ratio of each laser light source is set to Ra: Rb. It is a block diagram of control by an image pick-up signal processing part. It is a timing chart of the example of control of a drive pulse. It is a graph which shows the content of the pulse control with respect to each light quantity from the maximum light quantity to the minimum light quantity.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a diagram for explaining an embodiment of the present invention. FIG. 1 is a configuration diagram of an endoscope apparatus representing an endoscope and each apparatus to which the endoscope is connected. FIG. 2 is a specific example of the endoscope apparatus. It is an external view which shows a structural example.
As shown in FIG. 1, the endoscope apparatus 100 inputs information to an endoscope scope (hereinafter referred to as an endoscope) 11, a control device 13, a display unit 15 such as a monitor, and the control device 13. And an input unit 17 such as a keyboard and a mouse. The control device 13 includes a light source device 19 and a processor 21 that performs signal processing of a captured image.

  The endoscope 11 includes a main body operation unit 23 and an insertion unit 25 that is connected to the main body operation unit 23 and is inserted into a subject (body cavity). A universal cable 27 is connected to the main body operation unit 23, and the tip of the universal cable 27 is connected to the light source device 19 via a light guide (LG) connector 29A, and to the processor 21 via a video connector 29B. It is connected.

  As shown in FIG. 2, the main body operation unit 23 of the endoscope 11 switches a button for performing suction, air supply, and water supply on the distal end side of the insertion unit 25, a shutter button during imaging, and an observation mode. Various operation buttons 31 such as an observation mode switching button 30 are provided together with a pair of angle knobs 33.

  The insertion portion 25 is composed of a flexible portion 35, a bending portion 37, and a distal end portion (endoscope distal end portion) 39 in order from the main body operation portion 23 side. The bending portion 37 rotates the angle knob 33 of the main body operation portion 23. The bending operation is performed remotely by moving. Thereby, the front-end | tip part 39 can be turned to a desired direction.

  As shown in FIG. 1, an observation window 41 of an imaging optical system and light irradiation windows 43A and 43B of an illumination optical system are arranged at the endoscope front end 39. Reflected light from the subject due to illumination light emitted from each of the light irradiation windows 43 </ b> A and 43 </ b> B is captured by the image sensor 45 through the observation window 41. The captured observation image is displayed on the display unit 15 connected to the processor 21.

  Here, the imaging optical system includes optical elements such as a CCD (Charge Coupled Device) type image sensor and a CMOS (Complementary Metal Oxide Semiconductor) type image sensor, and a lens that forms an observation image on the imaging element 45. Member 47. The observation image formed and captured on the light receiving surface of the image sensor 45 is converted into an electric signal and input to the image signal processing unit 53 of the processor 21 through the signal cable 51, and is converted into a video signal by the image signal processing unit 53. The Although details will be described later, the imaging signal processing unit 53 functions as a light amount detection unit that detects the light amount of the subject image based on the imaging signal output from the imaging element 45.

  On the other hand, the illumination optical system includes a light source device 19, a pair of optical fibers 55A and 55B connected to the light source device 19, and wavelength converters 57A and 57B disposed at the light emitting ends of the optical fibers 55A and 55B, respectively. Have. The light source device 19 includes laser light sources LD1 and LD2 that are semiconductor light emitting elements, a light source control unit 59 that drives and controls each of the laser light sources LD1 and LD2, a combiner 61 that combines light emitted from the laser light sources LD1 and LD2, A coupler 63 that demultiplexes the combined light into two optical paths (a pair of optical fibers 55A and 55B), an amplitude value setting unit 65, and a drive signal generation unit 67, which will be described in detail later. That is, the light source device 19 functions as an illumination device that supplies illumination light to the distal end of the endoscope insertion portion.

  The laser light sources LD1 and LD2 are connected in common to the light source control unit 59 and emit light upon receiving a drive signal from the same light source control unit 59.

  The optical fibers 55A and 55B guide the laser light emitted from the laser light sources LD1 and LD2 to the endoscope distal end portion 39. The laser light guided to the endoscope distal end 39 generates white illumination light in which the light emitted from the wavelength conversion units 57A and 57B and the laser light are combined. The wavelength converters 57A and 57B include a phosphor that emits and emits light by laser light. The laser light sources LD1 and LD2 receive a drive signal from the light source control unit 59 based on a command from the endoscope control unit 69 provided in the processor 21 and emit light having a desired intensity.

  The endoscope control unit 69 is connected to a memory 71 as a storage unit that stores an imaging signal and various types of information, and an image processing unit 73. The endoscope control unit 69 performs appropriate image processing on the image data output from the imaging signal processing unit 53 by the image processing unit 73 and displays the image data on the display unit 15. In addition, the entire endoscope apparatus 100 is controlled such as being connected to a network such as a LAN (not shown) and distributing information including image data.

  The laser light source LD1 is a blue-emitting semiconductor laser having a central wavelength of 445 nm. The laser light source LD1 emits blue laser light whose emission light amount is controlled by the light source control unit 59, and the emitted light is irradiated to the wavelength conversion units 57A and 57B of the endoscope distal end portion 39 through the optical fibers 55A and 55B. . As this laser light source LD1, for example, a broad area type InGaN laser diode can be used.

The wavelength converters 57A and 57B absorb a part of the laser beam emitted from the laser light source LD1 and excite and emit green to yellow light (for example, YAG phosphor or BAM (BaMgAl ₁₀ O _37). ) And the like. As a result, as shown in FIG. 3, the laser light from the laser light source LD1 and the green to yellow excitation light obtained by wavelength conversion of the laser light are combined and shown in the profile S1, as shown in the spectral characteristics of the emitted light. White light is generated.

  The laser light source LD2 is a violet-emitting semiconductor laser having a central wavelength of 405 nm. The amount of light emitted from the laser light source LD2 is also controlled in the same manner, and is emitted from the light irradiation windows 43A and 43B of the distal end portion 39 of the endoscope. The light emitted from the laser light source LD2 is slightly wavelength-converted by the wavelength conversion units 57A and 57B compared with the light emitted from the laser light source LD1, and as shown by a profile S2 in FIG. 3, a narrowband light having a center wavelength of 405 nm. Is emitted.

Next, a procedure for special light observation using the endoscope apparatus 100 having the above-described configuration will be described.
The light source control unit 59 receives white illumination light from the laser light source LD1 (center wavelength 445 nm) and narrowband light from the laser light source LD2 (center wavelength 405 nm) individually in response to an instruction from the endoscope control unit 69. Controls the amount of emitted light.

For example, different observation images can be obtained by setting the emission light quantity ratio between the laser light source LD1 and the laser light source LD2 as follows.
(1) When LD1: LD2 is set to 1: 0, a white illumination image in the normal observation mode is obtained.
(2) When LD1: LD2 is set to about 1: 4, it is a narrow-band light observation mode, and an observation image in which capillaries and fine patterns on the surface of a living tissue are emphasized is obtained.
(3) LD1: LD2 about 7: If set to 1, a narrow band light observation mode, the observation image bright capillary vessels and fine patterns in the distant view is displayed can be obtained.
(4) When LD1: LD2 is set to 0: 1, a fluorescence observation image in the fluorescence observation mode is obtained.

  Here, FIG. 4 shows an example of the result of determining the contrast (luminance ratio) between the blood vessel and the mucous membrane according to the ratio of the emitted light quantity of the laser light sources LD1 and LD2. As shown in Evaluation Examples 1 to 7, the contrast between the blood vessel (observation target) and the mucous membrane (background image) in the observation image is 1.4 to 1.8 due to the change in the amount of light emitted from the laser light sources LD1 and LD2. In particular, when the contrast of Evaluation Examples 1 and 2 is 1.6 or more, sufficient surface layer blood vessel extraction capability can be obtained. Thus, a clear difference occurs in the observation image of the tissue surface layer according to the ratio of the emitted light quantity of the laser light sources LD1 and LD2.

  For this reason, it is possible to adjust the emission light amount ratio of the laser light sources LD1 and LD2 to a desired light amount ratio with high accuracy and to accurately match the total output light amount of the laser light sources LD1 and LD2 to the target light amount. This is important for obtaining an observation image of proper exposure in which information is projected well.

  FIG. 5 shows the target light amounts P1 and P2 of the laser light sources LD1 and LD2 so as to show the relationship between the output light amount with respect to the target light amount when the output light amount ratio LD1: LD2 of the laser light sources LD1 and LD2 is Ra: Rb. The individual emitted light quantity is controlled so that the ratio Ra: Rb of the emitted light quantity ratio is always kept constant even if the target light quantities P1 and P2 change. As a result, the sum of the emitted light amounts of the laser light sources LD1 and LD2 is controlled to the desired target light amount while the emitted light amount ratio of the laser light sources LD1 and LD2 is maintained at the desired light amount ratio.

Next, a procedure for increasing / decreasing the light emission intensity of the laser light sources LD1 and LD2 of the endoscope apparatus 100 as described above will be described.
First, an endoscope control unit is provided when an operator presses an observation mode switching button 30 provided in the main body operation unit 23 of the endoscope 11 illustrated in FIG. 1 and functioning as a light amount ratio setting unit and an observation mode selection unit. 69 performs control to switch to various observation modes such as normal observation, narrow-band light observation, and fluorescence observation. That is, in the normal observation mode, the emission light quantity ratio LD1: LD2 of the laser light sources LD1, LD2 is set to 1: 0. In the narrow-band light observation mode, LD1: LD2 is set to an arbitrary preset ratio such as 1: 4 or 7: 1. In the fluorescence observation mode, LD1: LD2 is set to 0: 1.

  In the narrow-band light observation mode, control is performed so that the total emitted light amount of the laser light sources LD1 and LD2 is set to the target light amount while the outputs of both the laser light sources LD1 and LD2 are maintained at the above-described emitted light amount ratio. Hereinafter, a procedure for generating desired illumination light by driving the laser light sources LD1 and LD2 in the narrow-band light observation mode will be described.

  First, at the time of endoscopic observation, the operator operates the observation mode switching button 30 so that the endoscope control unit 69 sets the emitted light amount ratio in a desired observation mode. The emission light quantity ratios Ra: Rb of the laser light sources LD1 and LD2 are prepared in advance and stored in the memory 71 so that they can be switched by the observation mode switching button 30. The endoscope control unit 69 reads out the emitted light amount ratio Ra: Rb corresponding to the observation mode designated by the observation mode switching button 30 and transmits it to the light source control unit 59.

  The light source control unit 59 receives the information of the emitted light amount ratio Ra: Rb transmitted from the endoscope control unit 69, and based on this emitted light amount ratio, the amplitude value setting unit 65, which is an amplitude value setting unit, uses the laser light source LD1. , The amplitude value (current value) of the individual drive signal for driving LD2 is set. Specifically, the current values of the individual drive signals of the laser light sources LD1 and LD2 are increased or decreased from the standard drive current value, and the integrated intensity of both the individual drive signals is set to the standard drive current value. Set to be equal to the integrated intensity.

  On the other hand, the endoscope control unit 69 sets the target light amount with respect to the total amount of light emitted from the laser light sources LD1 and LD2 based on the signal of the captured image from the image sensor 45.

  An imaging signal processing unit 53 provided in the processor 21 shown in FIG. 1 receives RAW data output from the imaging device 45 of the endoscope 11 connected to the processor 21 and receives an endoscope control unit 69 that is also a target light quantity setting unit. Outputs information on the target light amount for controlling the drive signals of the laser light sources LD1 and LD2 to the light source controller 59 so that the optimal illumination light amount according to the luminance information of the RAW data is obtained.

  FIG. 6 shows a block diagram of control by the imaging signal processing unit 53. The RAW data (raw image information) output from the image sensor 45 is input to the imaging signal processing unit 53, and the histogram creation unit 75 creates a histogram of the amount of light corresponding to the RAW data, and a photometric value calculation unit 77. Output to. The photometric value calculation unit 77 calculates a photometric value based on the input histogram and the brightness detection value obtained by various photometric modes (peak value, average value, etc.). Then, the target light amount calculation unit 79 obtains the target light amount of the next frame according to the calculated photometric value.

  The memory 71 stores the value of the target light amount with respect to the luminance information of the RAW data, and the endoscope control unit 69 refers to the memory 71 and corresponds to the luminance information input from the imaging signal processing unit 53. Find the target light intensity. The endoscope control unit 69 transmits this target light amount to the light source control unit 59. The target light amount is a value corresponding to the aperture value of a white light source such as a conventional xenon lamp. This target light quantity is expressed by, for example, 12-bit gradation (0 to 4096).

  Next, the individual drive signals of the laser light sources LD1 and LD2 are generated by common pulse modulation control based on the set amplitude and target light amount of the drive signal. The light source control unit 59 drives information on the target light amount with respect to the total light amount obtained by summing the amplitude value of the drive signal set by the amplitude value setting unit 65 in the drive signal generation unit 67 and the light amounts emitted from the laser light sources LD1 and LD2. It transmits to the signal generation part 67. The drive signal generation unit 67 obtains a drive pulse signal that is pulse-modulated in accordance with a target light amount, which will be described in detail later, and sets the amplitude of the drive pulse for each of the laser light sources LD1 and LD2 as an amplitude value setting unit 65. Change to the amplitude value set by.

That is, the drive pulse signal corresponding to the target light amount is commonly used, and the individual drive signal for driving the laser light source LD1 and the individual drive signal for driving the laser light source LD2 are generated based on the signal of the common drive pulse. , Respectively, by changing the amplitude value. The waveform patterns of the individual drive signal for driving LD1 and the individual drive signal for driving LD2 have a waveform pattern of drive pulses corresponding to the target light amount, and only the amplitude values thereof are different. In this way, a drive pulse corresponding to the target light amount is commonly obtained for each individual drive signal, and each of the individual drive signals is set to an amplitude value corresponding to a specified emission light amount ratio, thereby each laser light source LD1, The total light amount emitted from the LD 2 is matched with the target light amount. When the target light amount changes, the waveform pattern of the drive pulse is changed in common while the amplitude value of each individual drive signal is fixed. Thereby, even if the pulse modulation control is performed according to the change of the target light amount, the light amount ratio of the emitted light remains fixed, and the light amount ratios emitted from the laser light sources LD1 and LD2 are not disturbed.

  As described above, since the drive pulse corresponding to the target light amount is used in common for each individual drive signal, the modulation control is performed compared to the case where each individual control signal is individually subjected to pulse modulation control. Can be simplified. Further, even when a plurality of laser light sources are provided, the pulse modulation control for the target light quantity ratio of each laser light source can be shared by all the laser light sources, and the drive circuit can be prevented from becoming complicated.

Next, a specific example will be described in which the drive pulse for the total target light amount of the laser light sources LD1 and LD2 is obtained by pulse modulation control common to the laser light sources LD1 and LD2.
The light source control unit 59 shown in FIG. 1 receives the instruction from the endoscope control unit 69 and controls the lighting of the light emission amounts of the laser light sources LD1 and LD2 with a predetermined drive pulse. The driving pulse is generated by the endoscope control unit 69 with reference to the memory 71. The drive pulse is controlled using three types of control: pulse number control (PNM) and pulse density control (PDM) and pulse width control (PWM). Is done.

  FIG. 7 shows a timing chart of an example of driving pulse control. The drive pulse [1] for lighting all of the exposure period W of the electronic shutter within the period of one frame of the image defined by the vertical synchronization signal VD is the maximum light amount. Here, one frame period is 33 ms, and the shutter speed is 1/60 s. In addition, the frequency of the drive pulse [1] is 120 kHz, and 2000 pulses are included in the exposure period of the electronic shutter.

  When reducing the light intensity from the maximum light intensity of the drive pulse [1], PNM control in the first pulse modulation area, PDM control in the second pulse modulation area, and PWM control in the third pulse modulation area in descending order of the light intensity And gradually reduce the amount of light.

  First, in the PNM control, the number of pulses is reduced from the entire exposure period W of the electronic shutter by the back-alignment on the time axis, and the lighting period is shortened. That is, for the exposure period within one frame by the electronic shutter, as shown in drive pulse [2], the number of drive pulses is decreased so that the drive start timing is delayed until the predetermined minimum ratio is reached, and the laser light source Reduce the lighting period. Note that the maximum light amount may not be the entire exposure period W of the electronic shutter, but may be lit for the entire period of one frame, or may be continuously lit.

  Next, as shown in drive pulse [3], after the lighting period of the laser light source is shortened to a predetermined lighting period Wmin by PNM control, a process of thinning the drive pulse by PDM control is performed. In this PDM control, the pulse density in the lighting period is reduced by thinning out drive pulses at predetermined intervals with respect to the lighting period shortened to the predetermined lighting period Wmin.

  Then, as shown in the drive pulse [4], PDM control is performed until the pulse interval of the drive pulse reaches the thinning limit, that is, until the drive pulse reaches a predetermined minimum pulse density.

  Next, as shown in drive pulse [5], after the drive pulse reaches a predetermined minimum number of pulses, the pulse width of the drive pulse is reduced by PWM control. Then, as shown in drive pulse [6], PWM control is performed until the pulse width of the drive pulse reaches the PWM control limit.

  The contents of the control parameter information for each light quantity from the maximum light quantity to the minimum light quantity are summarized in FIG. The control parameter information shown in FIG. 8 and Table 1 is stored in the memory 71 shown in FIG. 1, and is referenced from time to time by the endoscope control unit 69 to generate a desired drive pulse.

  As described above, when the light amount is controlled to be reduced, the PNM control is first performed from the maximum light amount, so that the lighting period of the laser light source can be shortened and the occurrence of image blurring of the captured image due to blurring can be suppressed. Further, since the non-lighting time of the laser light source becomes longer, the effect of reducing the heat generation of the light source itself and each optical member on the optical path can be obtained as compared with the case of continuous lighting.

  In addition, by switching from PNM control to PDM control when the predetermined lighting period is shortened, an appropriate lighting period (144 pulses in the above example) is maintained, and flicker during movie observation can be suppressed.

  The number of pulses that is the lower limit of PDM control (16 pulses in the above example) can prevent the dimming resolution by PDM control from becoming coarse.

  PDM control is performed up to the drive pulse thinning limit, and the PDM control is switched to PWM control when the target light quantity is further reduced. In this PWM control, by changing the duty ratio of each drive pulse, the light quantity in the low light quantity region can be adjusted more finely than the thinning limit, and the dimming resolution is improved.

  By the way, when performing pulse lighting control of the laser light source, the laser light source causes illumination unevenness due to speckle noise. This speckle noise can be reduced by high frequency modulation driving. Therefore, in this control example, pulse driving at 120 kHz is always performed, and in order to obtain a sufficient speckle noise reduction effect, the upper limit of the duty ratio in PWM control is 95%.

  Further, the actual laser beam cannot follow the drive rising signal faithfully, and rises with a certain delay component. Similarly, it has a delay component at the time of falling. Therefore, if the drive pulse is an extremely narrow narrow pulse, it is expected to fall before reaching the target value. Therefore, the lower limit value of the duty ratio at which PWM control can be accurately performed is set to 7.8%. doing.

  The PNM / PDM control and the PWM control are switched according to the target light amount, and any one of the controls is used exclusively with the other controls. The dynamic range of the controllable light amount is 13.9: 1 in the range of maximum value 2000 to minimum value 144 in PNM control, 9: 1 in the range of maximum value 144 to minimum value 16 in PDM control, and in PWM control Is 12.2: 1 in the range of 95% maximum to 7.8% minimum. Therefore, by combining the controls, the controllable dynamic range is 1526: 1.

  When a dynamic range and dimming resolution equivalent to the above are realized by only PNM control, the pulse frequency is about 14.6 MHz (60 Hz × 1526 × 16), and a high-speed drive circuit for the laser light source is required. Similarly, when only PWM control is used, a pulse width control resolution of about 0.34 ns (1 / (120 k × 1526 × 16) is required, and a control circuit operating at about 3 GHz is required. By selecting and controlling PNM control and PDM control in accordance with each dimming area as compared with the method of controlling the light amount by PNM alone or PWM alone, the laser light source driving device can be greatly simplified.

The endoscope control unit 69 (see FIG. 1) considers the following points when calculating the target light amount of the next frame by detecting the RAW data from the image sensor 45 and the brightness in various photometric modes. Thus, it is preferable to set the light emission amount of each laser light source.
(1) Total light quantity limitation When the temperature of the laser light source is detected and the result exceeds a specified temperature, correction control is performed to subtract a predetermined value from the target light quantity control value. On the other hand, when the temperature is within the normal temperature range, a predetermined value is added to the light amount control value subjected to decrease control, and the target light amount control value before correction is restored. This correction control is performed to limit heat generation at the distal end portion of the endoscope.

(2) Correction of individual differences of optical components For the purpose of correcting the difference in model of optical components, the light amount control value of each laser light source after the light amount control of the entire apparatus is multiplied by a coefficient corresponding to the laser light source. However, in order to keep the total light quantity constant, the coefficients are set so that the sum of the coefficients becomes a constant value. In this configuration, since the combiner 61 (see FIG. 1) is used, this correction is unnecessary, but the light amount control value is corrected when light is individually emitted from a plurality of laser light sources.

  According to the illumination device described above and the endoscope device including the illumination device, the emitted light amount from each laser light source can be controlled to the target light amount with high accuracy without breaking the balance of the emitted light amount ratios of the plurality of laser light sources. Moreover, high responsiveness and stability can be obtained by using a semiconductor light source. Thereby, the illumination light of the endoscope in normal observation or special light observation can be accurately set to an arbitrary intensity, and a desired observation image can always be obtained.

  In addition, since the endoscope apparatus of this configuration realizes light source control equivalent to that of an existing configuration such as a xenon lamp, an existing processor can be used as it is, and a configuration with improved versatility can be achieved. Furthermore, since the light source life of the semiconductor light source is much longer than that of a xenon lamp or the like, the maintenance of the equipment can be reduced.

  Further, as a semiconductor light source for narrowband light illumination, a laser light source and a light emitting diode having a center wavelength of 360 to 530 nm can be used, and an enhanced image of capillaries and fine structures on the surface of a living tissue can be obtained. In addition, high-intensity illumination light can be obtained with both power savings.

  The present invention is not limited to the above-described embodiments, and those skilled in the art can change or apply the present invention based on the description of the specification and well-known techniques. included. For example, although an example using a laser light source as a semiconductor light source has been described, a configuration using a light emitting diode may be used. Further, the light amount control can be controlled by combining the exposure control by the electronic shutter of the imaging unit and the light amount control of the light source. In the above description, control of the amount of emitted light with respect to two semiconductor light sources has been described. However, the number of light sources is not limited to this, and any number of light sources may be used. Furthermore, the emitted light amount control can be performed with the amplitude of the drive voltage value instead of the amplitude of the drive current value.

As described above, the following items are disclosed in this specification.
(1) a plurality of semiconductor light sources that emit light having different spectra according to an input drive signal;
A target light amount setting means for setting a target light amount with respect to a total emitted light amount obtained by totaling the emitted light amounts from the plurality of semiconductor light sources;
A light amount ratio setting means for setting an output light amount ratio of the plurality of semiconductor light sources;
Amplitude value setting means for setting the amplitude value of each drive signal for each of the plurality of semiconductor light sources based on the set emitted light quantity ratio;
Drive signal generating means for generating each of the drive signals by a common pulse modulation control corresponding to the target light amount while maintaining the set amplitude value;
A lighting device.
According to this illuminating device, by setting the amplitude value of the drive signal in accordance with the output light amount ratio and holding the set amplitude value, the drive signal is generated by the common pulse modulation control in accordance with the target light amount. The pulse modulation control according to the target light amount can be performed with the output light amount ratio fixed, and the balance of the output light amount ratio of each semiconductor light source is not lost.

(2) The lighting device of (1),
An illumination device in which the plurality of semiconductor light sources are connected in common to the same drive signal generation unit.
According to this illumination device, the drive circuit is simplified by connecting each semiconductor light source to the same drive signal generating means and receiving the drive signal from the same drive signal generating means so that each semiconductor light source emits light. Is done.

(3) The lighting device according to (1) or (2),
An endoscope apparatus in which the amplitude value of the drive signal is set by increasing or decreasing the drive current value.
According to this illuminating device, the emission light quantity ratio can be set with high accuracy by simple current control by adjusting the amplitude of the drive signal by increasing or decreasing the drive current value.

(4) The lighting device according to any one of (1) to (3),
The semiconductor light source includes a light source for white light for generating white light and a light source for narrow band light for generating narrow band light having a predetermined wavelength range.
According to this illuminating device, the normal observation image and the special light observation image can be obtained in a desired manner by changing the emission light quantity ratio between the light source for white light for normal observation and the light source for narrow band light for special light observation. A desired endoscopic diagnostic image can be obtained by combining at a ratio.

(5) The illumination device according to (4),
The illumination device in which the narrowband light source emits narrowband light having a center wavelength of 360 to 530 nm.
According to this endoscope apparatus, it is possible to obtain an enhanced image of capillaries and fine structures on the surface of a living tissue by using narrowband light in the visible short wavelength region with a central wavelength of 360 to 530 nm.

(6) The illumination device according to (4) or (5),
The light source for white light includes a laser light source and a phosphor that emits light by light emitted from the laser light source, and the white light is emitted by mixing the light emitted from the laser light source and the light emitted from the phosphor. Lighting device to generate.
According to this endoscope apparatus, illumination light having a desired spectrum such as white light can be stably obtained with high light quantity controllability by a laser light source having a long light source lifetime.

(7) An illumination optical system that emits light emitted from the illumination device according to any one of (1) to (6) from the distal end of the endoscope insertion portion;
An imaging optical system for acquiring an observation image of the subject;
An endoscopic apparatus comprising:
According to this endoscope apparatus, the illumination light emitted toward the subject can be supplied without breaking the balance of the emitted light amount ratio of each semiconductor light source, and an observation image in which the feature amount is emphasized as intended is obtained. be able to.

(8) The endoscope apparatus according to (7),
Having an imaging means for adjusting the exposure period by an electronic shutter and imaging the subject;
Pulse modulation control by the drive signal generation means, in order of the target light amount,
A first pulse modulation control period for shortening the lighting period of the semiconductor light source by reducing the number of pulses of the drive pulse until the predetermined lighting period is reached with respect to the exposure period in one frame by the electronic shutter;
A second pulse modulation control period for reducing the pulse density in the lighting period by thinning out the drive pulse at a predetermined interval with respect to the predetermined lighting period in the first pulse modulation region;
A third pulse modulation control period for reducing the pulse width for each drive pulse having the minimum number of pulses in the second control range;
An endoscope apparatus that is implemented.
According to this endoscope apparatus, the pulse modulation by the drive signal generation unit is performed in the descending order of the target light amount with the first to third pulse modulation control periods. For this reason, when the target light quantity is high, priority is given to control for shortening the lighting time of the light source, image blurring of the captured image is suppressed, and heat generation is reduced. In addition, since a plurality of pulses exist within a predetermined lighting period for a low target light amount, occurrence of flicker can be suppressed.

(9) The endoscope apparatus according to (7) or (8),
The observation mode selection means for selecting any one of the observation modes from a plurality of observation modes different from each other in the observation image,
An endoscope apparatus in which the light amount ratio setting means sets the emitted light amount ratio according to the selected observation mode.
According to this endoscope apparatus, a specific emitted light quantity ratio is selected according to the observation mode, and the emitted light quantity of each semiconductor light source is controlled by the selected emitted light quantity ratio. Thereby, only by selecting the observation mode, the emitted light quantity of each semiconductor light source is controlled with the optimum emitted light quantity ratio for the selected observation mode.

(10) The endoscope apparatus according to any one of (7) to (9),
A light amount detecting means for detecting a light amount of the subject image based on an imaging signal output from the imaging element;
An endoscope apparatus in which the target light amount setting unit sets the target light amount based on a light amount detected by the light amount detection unit.
According to this endoscope apparatus, since the target light amount is set based on the luminance information of the captured observation image, the light amount from the next imaging is appropriate.

DESCRIPTION OF SYMBOLS 11 Endoscope 13 Control apparatus 19 Light source apparatus 21 Processor 25 Insertion part 30 Observation mode switching button 31 Operation button 39 Tip part
DESCRIPTION OF SYMBOLS 41 Observation window 43 Light irradiation window 45 Image pick-up element 53 Imaging signal processing part 57A, 57B Wavelength conversion part 59 Light source control part 65 Amplitude value setting part 67 Drive signal generation part 69 Endoscope control part 71 Memory 73 Image processing part 75 Histogram creation Unit 77 photometric value calculation unit 79 target light amount calculation unit 100 endoscope apparatus

Claims (10)

An endoscope apparatus having imaging means for generating illumination light using light emitted from a plurality of semiconductor light sources that emit light having different spectra and imaging reflected light from a subject by the illumination light,
A target light amount setting means for setting a target amount of the total amount of emitted light which is the sum of the amount of light emitted from the plurality of semiconductor light sources,
A light amount ratio setting means for setting an output light amount ratio of the plurality of semiconductor light sources;
An amplitude value setting means for setting the amplitude value of the driving signal to the plurality of semiconductor light sources based on the set light emission amount ratio,
In the narrow-band light observation mode, pulse modulation is performed in accordance with the target light amount set by the target light amount setting unit, and a driving pulse that is synchronized with an exposure period of the imaging unit is generated to drive the plurality of semiconductor light sources A single light source control means;
With
The semiconductor light source includes a white light source for generating white light, and a narrow band light source for generating narrow band light having a predetermined wavelength range,
The said light source control means is an endoscope apparatus which lights both the said light source for white light, and the said light source for narrow-band light in the same said exposure period.   The endoscope apparatus according to claim 1,
  The said light source control means is an endoscope apparatus which drives the said some semiconductor light source using the set said amplitude value in common using the produced | generated drive pulse.   The endoscope apparatus according to claim 1 or 2, wherein
  An endoscope apparatus in which the amplitude value of the drive signal is an amplitude value of a drive current of the semiconductor light source.   The endoscope apparatus according to any one of claims 1 to 3,
  The said light source control means is an endoscope apparatus which carries out increase / decrease control of the period which makes the said semiconductor light source light a pulse corresponding to the said target light quantity.   The endoscope apparatus according to claim 4, wherein
  The endoscope apparatus in which the light source control means controls a period during which the pulse lighting is performed only within a range of an exposure period of the imaging means.   An endoscope apparatus according to any one of claims 1 to 5,
  The plurality of semiconductor light sources is an endoscope apparatus having at least a semiconductor light source including a center wavelength of emitted light in a range of 360 to 530 nm.   The endoscope apparatus according to any one of claims 1 to 6,
  An endoscope apparatus in which the semiconductor light source is a light emitting diode.   The endoscope apparatus according to any one of claims 1 to 7,
  An endoscope apparatus that includes a phosphor that emits light by light emitted from the white light source, and that generates white illumination light by mixing light emitted from the white light source and light emitted from the phosphor.   The endoscope apparatus according to any one of claims 1 to 8,
  An endoscope having an endoscope insertion portion and an operation portion;
  The said light quantity ratio setting means is an endoscope apparatus provided in the said operation part.   An endoscope apparatus according to any one of claims 1 to 9,
  The imaging device is an endoscope apparatus including a CCD image sensor or a CMOS image sensor.

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