JP5749633B2 - Endoscope light source device - Google Patents

Description

  The present invention relates to an endoscope light source device that supplies illumination light including fluorescence emitted from a phosphor to an endoscope.

  As illumination light for normal observation in an endoscope, in addition to broadband light such as a xenon lamp, white light including fluorescence excited and emitted by a phosphor with excitation light has been used. In recent years, in order to perform special light observation such as highlighting of superficial microvessels, in addition to white light containing fluorescence, narrow-band light of a specific wavelength is also mixed and simultaneously irradiated into the body. .

  In this way, in the case of illumination using the fluorescence of the phosphor, it is possible to increase the brightness, and since installation space is not required as in the case of illumination such as a xenon lamp, the entire apparatus can be made compact. it can. On the other hand, some new problems that did not exist when using a xenon lamp or the like have also appeared. For example, when blue excitation light is also included as white light used during normal observation, the amount of green and red fluorescent light is determined by the amount of blue excitation light. In this case, since the amount of fluorescent light cannot be controlled independently regardless of the amount of excitation light, it may be difficult to match the color tone of white light. Further, when special light observation using an RGB imaging device is used, when blue excitation light is used and blue narrowband light is used as other narrowband light for special observation, it is fixed by simultaneous irradiation of these lights. If the amount of light exceeds the amount of light, there may be a problem that the B pixel of the RGB image sensor is saturated.

  In order to deal with these problems, Patent Document 1 uses ultraviolet excitation light as phosphor excitation light. Since the excitation light in the ultraviolet region is invisible light, even if the excitation light in the ultraviolet region is included in the illumination light, the color tone of the illumination light is not affected. In addition, since the excitation light in the ultraviolet region is completely shielded by the RGB imaging device, it is saturated even when a narrow band light for special observation with a relatively high light amount enters a special observation pixel such as a B pixel. There is no fear.

JP 2009-297311 A

  In the case of illumination using a phosphor, in addition to the above problems, there is a problem of temperature characteristics in which the light emission efficiency of the fluorescence is reduced due to heat generated when the fluorescence is excited and emitted. As shown in FIG. 13, the light emission efficiency of green fluorescence (G fluorescence) excited by the green phosphor and red fluorescence (R fluorescence) excited by the red phosphor decreases as the temperature of the phosphor increases. Further, the decrease in the emission efficiency of red fluorescence is larger than the decrease in the emission efficiency of green fluorescence, and the difference in the emission efficiency increases as the temperature increases.

  Therefore, when a green phosphor and a red phosphor are mixed and excited and emitted by mixing green phosphor and red phosphor, the mixed fluorescence will change in color tone as the temperature increases. (That is, color unevenness occurs). Therefore, it has been required to stabilize the color tone of illumination light including fluorescence emitted from the phosphor by preventing heat generation in the phosphor.

  Further, when irradiating a subject with a plurality of illumination lights having different wavelengths at the time of special observation, it is necessary to combine the illumination lights having a plurality of wavelengths. As a means for multiplexing, the use of a dichroic prism as shown in Patent Document 1 is conceivable. However, from the viewpoint of cost and installation space, a method of multiplexing is required without using an optical member such as a dichroic prism. ing.

  The present invention aims to prevent heat generation in the phosphor when generating illumination light including fluorescence excited by the phosphor and light of a plurality of wavelengths other than that, and to convert the fluorescence and the light of the plurality of wavelengths into a dichroic prism. An object of the present invention is to provide an endoscope light source device that can be combined without using an optical member such as the above.

In order to achieve the above object, the present invention emits excitation light having a wavelength region other than the visible light region in an endoscope light source device that supplies light to an endoscope inserted into a subject. An excitation light source, an illumination light source that emits first illumination light having a wavelength region in the visible light region, a first optical surface on which the excitation light is incident, and the excitation light are different from the first illumination light. A wavelength conversion unit that converts the wavelength of the illumination light into a second illumination light having a wavelength region of visible light, and the second illumination that is provided on the opposite side of the first optical surface and receives the first illumination light. a second optical surface for reflecting light, a wavelength converting unit that emitted from said first optical surface of the first illumination light and the second illumination light multiplexed by, emitted from the wavelength conversion means Supply means for supplying the first and second illumination lights to the endoscope. To.

The illumination light source is preferably provided directly on the second optical surface of the wavelength conversion means . The wavelength conversion unit is preferably provided on a transparent substrate, and the illumination light source is preferably provided on the second optical surface side of the wavelength conversion unit with the transparent substrate interposed therebetween. The transparent substrate is preferably heat radiating means for radiating heat generated in the wavelength conversion means. The transparent substrate is preferably composed of a sapphire substrate that is transparent and has high thermal conductivity.

Monitoring means for monitoring the light quantity of the first illumination light and the light quantity of the second illumination light , and controlling the light quantity of the first and second illumination light based on the result of the monitoring; It is preferable to include a heat generation prevention means for preventing heat generation at the wavelength conversion means or the illumination light source. Color tone stabilization means for stabilizing the color tone of the illumination light including the first and second illumination lights by independently controlling the light quantity of the first illumination light and the light quantity of the second illumination light. It is preferable to provide.

The wavelength converting means is a green phosphor having an excitation wavelength band in an ultraviolet region, the illumination light source is a semiconductor light source, the first illumination light is light emitted from the semiconductor light source, The illumination light 2 is preferably green fluorescence excited and emitted from the green phosphor by the excitation light in the ultraviolet region.

  It is preferable that the endoscope is supplied with white light in which the first illumination light including the blue band and the red band and the second illumination light of green fluorescence are mixed. The endoscope is supplied with white light in which the first illumination light including the blue band and the red band and the second illumination light of green fluorescence are mixed, and the peak intensity in the blue band of the first illumination light is: It is preferable that the green fluorescence and the peak intensity in the red band of the first illumination light be larger.

  According to the present invention, the first illuminating light emitted from the illuminating light source and the second illuminating light excited and emitted by the exciting light are multiplexed in the wavelength converting means, so that an optical such as a dichroic prism is used. Without using a member, it is possible to multiplex the wavelength-converted light and other wavelengths of light.

  Further, since the excitation light is incident and the second illumination light is emitted through the same first optical surface, an illumination light source is provided on the second optical surface side opposite to the first optical surface. In addition, it is possible to provide a heat dissipating means for dissipating heat generated by the wavelength converting means. Thereby, the change of the color tone of the illumination light by the heat generation in the wavelength conversion means can be prevented. Further, in order to make the excitation light incident and the second illumination light emitted through the same first optical surface, it is necessary to make the excitation light obliquely incident on the same. For this purpose, a considerable space is required in which the excitation light source and the wavelength conversion member can be spatially separated, but such a space is not an endoscope that is inserted into the subject, but the endoscope. If it is a light source device connected to, it is possible to ensure enough.

It is a figure which shows the outline of an endoscope system. It is a figure which shows the internal structure of the light source device and processor device in 1st Embodiment. It is a figure for demonstrating the incident angle of the excitation light which injects diagonally with respect to the fluorescent substance without an AR film. It is a figure for demonstrating the incident angle of the excitation light which injects diagonally with respect to the fluorescent substance with AR film | membrane. It is a graph which shows the spectral transmission factor of the excitation light with respect to fluorescent substance. It is a graph which shows the spectral transmittance of a dichroic mirror, and the emitted light intensity of 1st blue light, 2nd blue light, green fluorescence, and red light. It is a graph which shows the light emission pattern and light emission intensity in normal light observation mode. 5 is a graph showing a light emission pattern and light emission intensity in a first special light observation mode. It is a graph which shows the light emission pattern and light emission intensity in 2nd special light observation mode. It is a graph which shows the light emission pattern and light emission intensity in oxygen saturation observation mode. It is a figure for demonstrating PNM, PDM, and PWM. It is a graph which shows the spectral transmittance of a color image sensor. It is a figure for demonstrating the production | generation method of a normal light image. It is a figure for demonstrating the production | generation method of a 1st special light image. It is a figure for demonstrating the production | generation method of a 2nd special light image. It is a figure for demonstrating the production | generation method of an oxygen saturation image. It is a figure which shows the internal structure of the light source device and processor device in 2nd Embodiment. It is a figure which shows the internal structure of the light source device and processor device in 3rd Embodiment. It is a figure which shows the internal structure of the light source device and processor device in embodiment different from 1st-3rd embodiment. It is a graph which shows the temperature characteristic of fluorescent substance.

  As shown in FIG. 1, an endoscope system 10 according to a first embodiment includes an electronic endoscope 11 that images an inside of a subject, a light source device 12 that generates light that illuminates the subject, and an electronic endoscope. The image processing apparatus 13 includes a processor device 13 that generates an image based on an image pickup signal from the image sensor and performs various types of image processing, and a monitor 14 that displays an endoscopic image.

  In this endoscope system 10, a normal light observation mode in which a normal light image in a subject illuminated with white light is displayed on the monitor 14, the fine blood vessels and fine structures on the surface layer are highlighted on the normal light image. A first special light observation mode for displaying a first special light image on the monitor 14; a second special light observation mode for displaying a second special light image in which surface microvessels and middle-deep blood vessels are represented in pseudo color on the monitor 14; There are provided four modes of an oxygen saturation observation mode in which an oxygen saturation image obtained by imaging the oxygen saturation of blood hemoglobin is displayed on the monitor 14. These modes are appropriately switched by mode switching SW15.

  The electronic endoscope 11 includes a flexible insertion portion 16 to be inserted into a body cavity, an operation portion 17 provided at a proximal end portion of the insertion portion 16, an operation portion 17, a light source device 12, and a processor device 13. And a universal cord 18 for connecting the two. A bending portion 19 in which a plurality of bending pieces are connected is formed at the distal end of the insertion portion 16. The bending portion 19 is bent in the vertical and horizontal directions by operating the angle knob 21 of the operation portion. At the distal end of the bending portion 19, a distal end portion 16 a incorporating a color imaging element 20 (for example, a color CCD) that images the inside of the body cavity is provided. The distal end portion 16 a is directed in a desired direction within the body cavity by the bending operation of the bending portion 19.

  A connector 24 is attached to the universal cord 18 on the light source device 12 and the processor device 13 side. The connector 24 is a composite type connector including a communication connector and a light source connector, and the electronic endoscope 11 is detachably connected to the light source device 12 and the processor device 13 through the connector 24.

  A light guide 25 and a signal cable 26 are provided inside the electronic endoscope 11. The light guide 25 is a bundle optical fiber capable of guiding a plurality of types of light having different wavelengths, and guides the light from the light source device 12 to the distal end portion 16a. The guided light is emitted from the distal end portion 16a toward the body cavity. The signal cable 26 sends the imaging signal from the imaging device to the processor device 13.

  As shown in FIG. 2, the light source device 12 includes an excitation light source 30 that emits excitation light having a wavelength range in the ultraviolet region, green fluorescence that emits excitation light by excitation light from the excitation light source 30, and a first light having a center wavelength of 405 nm. A light emitting unit 31 that emits blue light, second blue light having a central wavelength of 470 nm, and red light having a central wavelength of 625 nm, and the amount of green fluorescence, first blue light, second blue light, or red light is detected from the light emitting unit 31. The light guide 25 is combined with the monitoring unit 35, the light emitted from the green fluorescent light, the first blue light, the second blue light, and the light source control unit 37 that controls the light emission intensity and the light emission timing of the red light, and the light transmitted through the monitoring unit 33. And a condensing lens 39 that condenses toward the incident surface.

  The excitation light source 30 is composed of a semiconductor light source such as a laser diode or a light emitting diode. The excitation light source 30 emits excitation light for exciting and emitting green fluorescence from the phosphor of the light emitting unit 31. This excitation light has a peak wavelength at 365 nm, 380 nm, or 395 nm within the wavelength range of the ultraviolet region which is a non-visible light region. The excitation light is irradiated toward the phosphor 42 of the light emitting unit 31 through the irradiation lens 30a.

  The light emitting unit 31 includes a phosphor 42 that emits green fluorescence by excitation light, a first blue light source 45 that emits first blue light having a central wavelength of 405 nm, and a second blue light source that emits second blue light having a central wavelength of 470 nm. 46, a red light source 47 that emits red light having a center wavelength of 625 nm, a light source substrate 49 having a substantially rectangular parallelepiped shape provided with these light sources, and heat dissipation that dissipates heat generated by the phosphor 42 and the light sources 45 to 47. Part 50.

The phosphor 42 is formed by being hardened with a glass resin or the like and a binder, and has a substantially rectangular parallelepiped shape. The phosphor 42 has a high light absorption characteristic for excitation light in the ultraviolet region, but has no light absorption characteristic for a visible light region exceeding a wavelength of 400 nm (excitation wavelength band is ultraviolet). The excitation light that is invisible light belongs to the excitation wavelength band of the phosphor 42, but the first blue light, the second blue light that are visible light, The wavelength range of red light does not belong to the excitation wavelength band of the phosphor 42). In accordance with this, a fluorescent material that emits green fluorescent light with high light emission intensity and light emission efficiency is used. In the present embodiment, “BaMgAl ₁₀ O ₁₇ : Eu, Mn” is used as a phosphor satisfying these conditions. “BaMgAl ₁₀ O ₁₇ : Eu, Mn” has an absorption rate of “66.8%” for the excitation light when the peak wavelength of the excitation light is “378 nm”, and the luminous efficiency is “55.8%”. Is. The light absorption rate and the light emission efficiency are higher than “Li _0.6 Na _0.4 W ₂ O ₈ ”, and the light emission intensity is higher than “Li _0.6 Na _0.4 W ₂ O ₈ ”.

  The first blue light source 45 emits first blue light having a center wavelength of 405 nm, the second blue light source 46 emits second blue light having a center wavelength of 470 nm, and the red light source 47 emits red light having a center wavelength of 625 nm. The light source substrate 49 is formed on the phosphor mounting surface side and includes a substantially concave light source installation portion 49a for installing the three light sources 45 to 47.

  The first blue light source 45, the second blue light source 46, and the red light source 47 are configured by semiconductor light sources such as a laser diode and a light emitting diode, similarly to the excitation light source 30. The light sources 45 to 47 are controlled in light emission timing and light quantity by a light source control unit via a common light source substrate 49.

  In the present embodiment, excitation light is incident on the phosphor 42 obliquely in order to perform excitation light incidence and green fluorescence emission on the same plane. In order to realize the oblique incidence of the excitation light, the excitation light source 30 and the phosphor 42 are installed spatially separated from each other. Excitation light from the excitation light source 30 enters the phosphor 42 through the convex lens 60 and the first optical surface 42 a of the phosphor 42. Part of the excitation light incident on the phosphor 42 is absorbed by the phosphor 42 and emits green fluorescence. The excited green light is emitted through the first optical surface 42a.

  On the other hand, the light that has not been absorbed by the phosphor 42 is reflected by the optical filter 43 provided on the second optical surface 42b opposite to the first optical surface 42a. The optical filter 43 has reflection characteristics in the wavelength range of the excitation light, and has transmission characteristics in the wavelength ranges of the first blue light, the second blue light, and the red light. The excitation light reflected by the optical filter 43 is absorbed by the phosphor 42 and emits green fluorescence. The excited green light is emitted from the first optical surface 42a. The green fluorescence emitted from the first optical surface 42 a is emitted toward the monitoring unit 35 through the convex lens 60.

  Further, the first blue light, the second blue light, and the red light other than the green fluorescence are emitted to the monitoring unit 35 through the phosphor 42. Therefore, the phosphor 42 and the phosphor mounting surface of the light source substrate 49 are bonded with silicon grease or the like (not shown) having low thermal resistance (high heat conductivity). The first blue light, the second blue light, and the red light from each of the light sources 45 to 47 enter the phosphor 42 through the optical filter 43 having transmission characteristics for the light. Since none of these lights are included in the excitation wavelength band of the phosphor 42, the fluorescence is emitted from the first optical surface 42a without being excited and emitted. The first blue light, the second blue light, and the red light emitted from the first optical surface 42 a are emitted toward the monitoring unit 35 through the convex lens 60.

  As described above, the excitation light is incident and the green fluorescence is emitted from the same first optical surface 42a, and the first blue light and the second blue other than the green fluorescence are formed on the opposite second optical surface 42b side. By providing light emitting means for emitting light and red light, the green fluorescence, the first blue light, the second blue light, and the red light are multiplexed without using a multiplexing means such as the dichroic prism disclosed in Patent Document 1. be able to. The convex lens 60 is designed so that the green fluorescence emitted from the phosphor 42 and the first blue light, the second blue light, and the red light emitted from the light sources 45 to 47 are located on the optical axis of the light guide 25. Therefore, the light combined with the light is irradiated into the body without color unevenness. Further, in the present embodiment, in order to make the excitation light incident on the phosphor 42 obliquely, an installation space for installing the excitation light source 30 spatially separated from the phosphor 42 is necessary. In this respect, it is easier to secure the installation space in the light source device than in the distal end portion 16a of the electronic endoscope.

  In addition, among the illumination light that illuminates the inside of the subject, green fluorescence is used as green light instead of a semiconductor light source such as an LED for the following reason. As the ride guide 25 of the endoscope, one having a small diameter is used from the viewpoint of reducing the diameter of the insertion portion, so that the light incident portion is small. Therefore, it is necessary to make illumination light with high luminance enter the light guide 25. That is, a light source having a large output per unit area is required. At present, it is known that blue light and red light of illumination light can be emitted with high brightness by a semiconductor light source such as LED and LD. On the other hand, for the green light, three light emitting means of a green LED, a green semiconductor laser, and a green phosphor can be considered.

  As for the green LED, there is only an LED element whose luminous efficiency is drastically decreased from blue to red like the current gallium nitride LED. Further, even if a high-brightness LED can be manufactured, it is conceivable that the half width is narrower than that of the laser diode. Therefore, when it is used as illumination for an endoscope, the light emission half-value width becomes too narrow, so that the color rendering property may be inferior. On the other hand, although the green semiconductor laser is a high-intensity light source, the emission half-value width is too narrow. Therefore, when used as illumination light, it is difficult to obtain a reflection signal such as an object having steep light absorption or reflection (for example, a dye used in an endoscope). At present, the green semiconductor laser has problems in terms of output and life.

  On the other hand, the green phosphor does not have a problem like the green LED and the green semiconductor laser. Therefore, green phosphor is most suitable as the light emitting means used for endoscope illumination.

  When excitation light is incident on the phosphor 42, it is preferable that the excitation light is not reflected by the first optical surface 42a. If the excitation light reflected by the first optical surface 42a is irradiated into the body through the light guide 25, several problems may occur. As one of the problems, since the excitation light can also be an excitation light for an autofluorescent substance in a living tissue, unnecessary autofluorescence may be excited and emitted from the body. Since this unnecessary autofluorescence is noise for the observation image, it is preferable that excitation light does not enter the body.

For example, as shown in FIG. 3A, when an AR (Anti Reflection) film is not provided on the incident / exit surface 42a, the polarization plane of the excitation light is p-polarized, and the incident angle θ of the excitation light is the Brewster angle. “56 °” is preferable (θ = ArcTan (n2 / n1) (n1: refractive index of air, n2 (1.5): refractive index of phosphor-containing glass))). As shown in FIG. 3B, when the AR film 50 is provided on the incident / exit surface 42a, it is preferable that the polarization plane of the excitation light is p-polarized and the incident angle θ of the excitation light is “50 °”. (Θ = ArcTan (n2 / n1) (n1: refractive index of air, n2 (1.5): refractive index of phosphor-containing glass))). Here, the AR film 50 is composed of a magnesium fluoride MgF ₂ (refractive index n3, approximately 1.38) film 50a and alumina Al ₂ O ₃ (refractive index n4, approximately 2.1 to 2.4. When changed, it is preferable to form the film 50b of 2.3). With regard to magnesium fluoride MgF ₂ and alumina Al ₂ O ₃ , it is preferable that the thickness is ½λ respectively when the design wavelength λ is 405 nm. Therefore, the refractive index is preferably in the relationship of n1 <n3 <n2 <n4.

  3A and 3B, as shown in the transmission distribution T (p) of FIG. 4, the transmittance to the phosphor 42 around “365 nm, 380 nm, or 395 nm” that is the peak wavelength of the excitation light. Is close to “99.98%”. Therefore, the excitation light is reliably incident on the phosphor 42 without being reflected by the first optical surface 42a. When the polarization plane of the excitation light is s-polarized light, the transmittance around “365 nm, 380 nm, or 395 nm” is “90%” as shown in the transmission distribution T (s). About 10% of the excitation light to be reflected is reflected by the first optical surface 42a.

  As shown in FIG. 2, the heat radiating unit 50 is provided with a Peltier element 52, a heat sink 54, and a fan 56 in order from the phosphor 42 and the light source substrate 49 side. The Peltier element 52 includes a cooling plate 52 a attached to the Peltier attachment surface of the light source substrate 49 and a heat radiating plate 52 b provided on the heat sink 54 side. By driving the Peltier element 52 by an element driving unit (not shown), the heat generated in the phosphor 42 and the light source substrate 49 moves to the heat radiating plate 52b side through the cooling plate 52a. The heat sink 54 is provided with a plurality of metal square pillars so that heat generated from the heat radiating plate 52b is easily diffused. Wind from the fan 56 is blown against the heat sink 54. Thereby, the heat accumulated in the heat sink 54 is dissipated to the outside of the light source device 12.

  The monitoring unit 35 transmits most of the first blue light, the second blue light, the green fluorescence, and the red light from the light emitting unit 31 toward the condensing lens 39 as shown in the spectral transmission distribution Ta in FIG. On the other hand, a dichroic mirror 72 that reflects a small amount of light for detecting the amount of light, a first blue light PD (Photo Detector) 74a that monitors the amount of light reflected by the dichroic mirror 72, a second blue light PD 74b, It includes four photosensors, a green fluorescent PD 74c and a red light PD 74d. The monitoring results of the first blue light PD 74a, the second blue light PD 74b, the green fluorescence PD 74c, and the red light PD 74d are transmitted to the light source control unit 37.

  The light source control unit 37 has the excitation light source 30, the first blue light source 45, the second blue light source 46, and the red so that the light quantity ratio among the first blue light, the second blue light, the green fluorescence, and the red light is constant. The light source 47 is controlled. The light amount control of the excitation light source 30 is performed by the excitation light control unit 37a, the light amount control of the first blue light source 45 is performed by the first blue light control unit 37b, and the light amount control of the second blue light source 46 is performed by the second blue light control unit. 37c, and the light amount control of the red light source 47 is performed by the red light control unit 37d. These control units 37a to 37d enable independent light quantity control of the first blue light, the second blue light, the green fluorescence, and the red light. Further, while each light is emitted, the light amount is kept constant by the light amount feedback control based on the monitoring results of the PDs 74a to 74d.

  The light emission timing and the light amount ratio of the first blue light, the second blue light, the green fluorescence, and the red light are predetermined for each mode. When the normal light observation mode is set, as shown in FIG. 6A, first blue light, green fluorescence, and red light are emitted. At this time, light is emitted so that the peak intensities are the same. Therefore, the inside of the body is irradiated as white light in which the first blue light, green fluorescence, and red light are mixed.

  Here, since the first blue light, green fluorescence, and red light can be independently controlled in light quantity, their light quantity ratios can be kept constant. In addition, since the excitation light is outside the visible light region, even if the excitation light enters the body, the color of white light is not affected. From the above, the color of the white light irradiated into the body is kept constant without changing.

  When the first special light observation mode is set, as shown in FIG. 6B, first blue light, green fluorescence, and red light are emitted. At this time, the first blue light is emitted so that the peak intensity of the first blue light is higher than the peak intensity of the other green fluorescence and red light, and the contrast ratio between the blood vessel and the mucous membrane in the body becomes “1.6” or more. Light is emitted at the first light quantity ratio. As described above, the first blue light, the green fluorescence, and the red light can be independently controlled in light quantity, so that the first light quantity ratio can be kept constant.

  When the second special light observation mode is set, as shown in FIG. 6C, first blue light and green fluorescence are emitted. At this time, light is emitted at a second light quantity ratio at which the contrast ratio between the blood vessel and the mucous membrane in the body is “1.6” or more. As described above, since the first blue light and the green fluorescence can be controlled independently, the second light quantity ratio can be kept constant.

  When the oxygen saturation observation mode is set, as shown in FIG. 6D, the emission of only the second blue light and the emission of green fluorescence and red light are alternately repeated every frame. At this time, light is emitted such that the third light quantity ratio among the second blue light, green fluorescence, and red light is constant. As described above, the amount of light of the second blue light, green fluorescence, and red light can be controlled independently, so that the third light amount ratio can be kept constant.

  Note that the light amount control by the light source control unit is preferably performed by pulse modulation control based on a predetermined driving pulse for the light emission amount of each light source. The pulse modulation control is performed by pulse number control (PNM), pulse density control (PDM: Pulse Density Modulation), and pulse width control (PWM: Pulse Width Modulation).

  Specifically, as shown in FIG. 7, the light amount control is performed by performing pulse modulation of any one of PNM, PDM, and PWM during the charge accumulation period of the color image sensor 20 in one frame. Here, in FIG. 7, the light sources 30, 45 to 47 are turned on when the pulse rises, and the light sources are turned off at other times. Note that one frame period is 33 ms and the shutter speed is 1/60 s. At the maximum light amount, as shown in the drive pulse [1], 2000 pulses are included in the charge accumulation period of the color image sensor 20 (frequency is 120 kHz).

  When reducing the light amount between the maximum light amount and the minimum light amount, first the number of pulses is reduced by PNM control, then the pulse density is reduced by thinning out the pulses by PDM control, and finally the pulse width by PWM control. The amount of light is gradually reduced by narrowing.

  In the PNM control, as shown in the drive pulse [2], the number of pulses is decreased within the charge accumulation period to shorten the lighting period. As the number of pulses decreases, the amount of light also decreases. Then, as shown in drive pulse [3], after shortening to a predetermined lighting period Wmin by PNM control, a process of thinning drive pulses 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 a certain limit width (PWM control limit).

  By using the pulse modulation method, even if the light emission wavelength varies in accordance with the amount of light in a semiconductor light emitting device such as a semiconductor laser or a light emitting diode, the variation in the color tone of the illumination light can be minimized. Moreover, although the luminous efficiency of the phosphor 42 is also dependent on the excitation wavelength, fluctuations in the luminous efficiency can be further suppressed by the pulse modulation.

  As illustrated in FIG. 2, the processor device 13 generates an observation image in the subject based on the reception unit 80 that receives the imaging signal from the electronic endoscope 11 and the imaging signal received by the reception unit 80. In addition to the image generating unit 81, the receiving unit 80 and the image generating unit 81, the light source control unit 37 in the light source device 12, the mode switching SW 15 of the electronic endoscope 11, the monitor 14 and the like are electrically connected to the processor device. And a controller 82 that controls the entire system 12 in an integrated manner.

  The receiving unit 80 receives an imaging signal output from the color imaging element 20 of the electronic endoscope 11. The color image pickup device 20 includes a large number of B pixels, G pixels, and R pixels provided with B filters, G filters, and R filters having spectral transmittances as shown in FIG. Therefore, when the color imaging element 20 images the inside of the subject, a blue signal is output from the B pixel, a green signal is output from the G pixel, and a red signal is output from the R pixel for each frame.

  The image generation unit 81 generates an observation image corresponding to the set mode. When the normal light observation mode is set, as shown in FIG. 9A, a normal light image is generated based on the blue signal Bc, the green signal Gc, and the red signal Rc from the reception unit. In the normal light observation mode, white light having the same peak intensity of each color (blue, green, red) is irradiated into the body, so that each signal Bc, Gc, Rc has substantially the same signal value. . Accordingly, a bright normal light image is displayed on the monitor 14 as a whole.

  When the first special light observation mode is set, as shown in FIG. 9B, the first special light image is generated based on the blue signal Bm, the green signal Gm, and the red signal Rm from the receiving unit. To do. In the first special light observation mode, white light whose blue peak intensity is higher than other colors (green, red) is irradiated into the body, so that the blue signal Bm has a higher signal value than the green signal Gm and the red signal Rm. have. That is, the blue signal Bm contains a large amount of information of blue components such as microvessels and microstructures on the surface layer. Therefore, the monitor 14 displays the first special light image in which the fine blood vessels and the fine structure of the surface layer are clearly displayed on the normal light image that is bright overall.

  When the second special light observation mode is set, as shown in FIG. 9C, a second special light image is generated based on the blue signal Be and the green signal Ge from the reception unit. When generating the second special light image, the blue signal Be is assigned to the B and G channels for monitor display, and the green signal Ge is assigned to the R channel for monitor display. Therefore, the monitor 14 has a second special light image in which the information on the surface blood vessels included in the blue signal Be is a brown tone pattern and the information on the middle and deep blood vessels included in the green signal Ge is expressed in a cyan tone pattern. Is displayed.

  When the oxygen saturation observation mode is set, as shown in FIG. 9D, a blue signal B1 obtained when the second blue light is emitted, a green signal G2 obtained when the green fluorescence and the red light are emitted, An oxygen saturation image is generated based on the red signal R2. At the center wavelength 470 nm of the second blue light, the absorption coefficients of oxyhemoglobin and reduced hemoglobin are greatly different, so the blue signal B1 contains a lot of information on the oxygen saturation. Therefore, a change in oxygen saturation can be visually grasped from the oxygen saturation image displayed on the monitor 14. Further, since the second blue light does not belong to the excitation wavelength band of the phosphor 42, unnecessary fluorescence is not emitted from the phosphor 42. Therefore, even if the second blue light passes through the phosphor 42, the subject is irradiated with pure second blue light that does not contain a fluorescent component. Therefore, the blue signal B1 includes only the wavelength component of the second blue light indicating the oxygen saturation change information. As a result, it is possible to display on the monitor 14 an oxygen saturation image that reflects accurate oxygen saturation information.

  Unlike the first embodiment in which the phosphor 42 is directly attached to the light source substrate 49, the second embodiment of the present invention is attached to the phosphor substrate 100 as shown in FIG. The light source substrate 49 is attached to the phosphor substrate 100 at a predetermined interval. Since other than that is the same as that of 1st Embodiment, detailed description is abbreviate | omitted.

  The phosphor substrate 100 is formed of a transparent substrate having high thermal conductivity such as sapphire. A phosphor 42 is attached to the phosphor attachment surface at the center of the phosphor substrate 100, and two heat dissipating parts 103, 104 similar to the heat dissipating part 50 are attached to the periphery thereof. The phosphor mounting surface is tapered, and this phosphor mounting surface has reflection characteristics in the wavelength range of the excitation light, while in the wavelength range of the first blue light, the second blue light, and the red light. Is provided with an optical filter 101 having transmission characteristics. Therefore, since the excitation light from the excitation light source 30 is reflected by the optical filter 101, it is reliably absorbed by the phosphor 42. Thereby, green fluorescence is excited and emitted from the phosphor 42. The excited green light is emitted toward the monitoring unit 35 through the convex lens 60.

  On the other hand, the first blue light, the second blue light, and the red light from the first blue light source 45, the second blue light source 46, and the red light source 47 are transmitted through the optical filter 101 through the transparent phosphor substrate 100. . As a result, the first blue light, the second blue light, and the red light enter the phosphor 42. Since these lights do not belong to the excitation wavelength region of the phosphor 42, they pass through the phosphor 42 as they are. The light transmitted through the phosphor 42 is emitted toward the monitoring unit 35 via the convex lens 60.

  In the second embodiment, since the heat generated in the phosphor 42 and the heat generated in each of the light sources 45 to 47 are radiated by separate heat radiating portions, the temperature of the phosphor 42 is kept constant without increasing, The light sources 45 to 47 are not affected by the temperature. Thereby, since there is no fall of the luminous efficiency in the fluorescent substance 42 and each light source 45-47, stabilization of the color tone of the illumination light irradiated into a body can be aimed at.

  The third embodiment of the present invention differs from the first embodiment in which the heat generated by the phosphor 42 and each of the light sources 45 to 47 is radiated using the heat radiating section 50 such as the Peltier element 52, as shown in FIG. The heat generation of the phosphor 42 and each of the light sources 45 to 47 is prevented only by the light amount feedback control based on the monitoring result in the monitoring unit 35 without using the heat radiating unit. Since other than that is the same as that of 1st Embodiment, detailed description is abbreviate | omitted.

  In the light source control unit 37 according to the third embodiment, when the monitoring unit 35 detects a decrease in the light amount of a certain level or more, it does not increase the light amount of the light whose light amount has decreased, but reduces the heat generation amount by reducing the light amount. Reduce. For example, when the amount of green fluorescent light decreases, the amount of heat generated in the phosphor 42 is reduced by reducing the amount of excitation light. Moreover, when the light quantity of 1st blue light falls, the emitted-heat amount in a 1st blue light source is reduced by reducing the light quantity of the 1st blue light source 45. FIG. As described above, since the amount of heat generation can be sufficiently reduced only by adjusting the light amount of the light source, heat generation can be prevented without separately providing costly heat radiating means such as a Peltier element. When the amount of light is reduced to prevent heat generation, it is preferable to display that fact on the monitor 14.

  In the first to third embodiments, the first blue light, the second blue light, and the red light other than the green fluorescence are incident on the light guide 25 after passing through the phosphor 42. Instead, as shown in FIG. 12, the first blue light source 45, the second blue light source 46, and the red light source 47 are installed on the same plane as the phosphor 42, so that the light from these light sources 45 to 47 is converted into the phosphor. 42 may be incident on the light guide 25 without passing through.

  In this case, the first blue light source 45, the second blue light source 46, the red light source 47, and the phosphor 42 are provided on the same phosphor / light source substrate 150. The phosphor / light source substrate 150 is the same as the light source substrate 49. Further, a heat radiating portion 152 similar to the heat radiating portion 50 is attached to the phosphor / light source substrate 150. The heat radiating unit 152 radiates heat generated by both the phosphor 42 and the light sources 45 to 47. The phosphor 42 is provided with a highly reflective portion 153 (formed of silver, aluminum, or an alloy thereof) that reflects excitation light or green fluorescence.

  Further, on the phosphor / light source substrate 150, the excitation light from the excitation light source 30 is condensed and the first blue light, the second blue light, the green fluorescence, and the red light are collected as in the above embodiment. A convex lens 155 that collects light toward the monitoring unit 35 is provided. The convex lens 155 is optically designed so that the excitation light from the excitation light source 30 is condensed only on the phosphor 42. In addition, the convex lens 155 causes the green fluorescence excited and emitted from the phosphor 42 and the first blue light, the second blue light, and the red light emitted from the light sources 45 to 47 to approach the optical axis of the light guide 25 as much as possible. So that it is optically designed.

  In the above embodiment, blue light (first and second blue light) and red light are emitted from the semiconductor light source, and green fluorescence is excited and emitted from the phosphor. Instead, blue light and green light are emitted. For light, light may be emitted from a semiconductor light source, and for red light, red fluorescence may be excited and emitted from a red phosphor.

  In the above embodiment, in order to prevent excitation light in the ultraviolet region from entering the subject, the excitation light is cut or dimmed on the optical path from the phosphor to the tip of the electronic endoscope. It is preferable to provide an excitation light cut filter. Further, by using a light guide having extremely low transmission characteristics in the ultraviolet region, the excitation light may be cut or dimmed by the ride guide.

12 Light source device 30 Excitation light source 37 Light source control unit 42 Phosphor 45 First blue light source 46 Second blue light source 47 Red light source 50, 103, 104, 152 Radiation unit 74a First blue light PD
74b Second blue light PD
74c Green fluorescent PD
74d PD for red light
100 Phosphor substrate

Claims (10)

In an endoscope light source device that supplies light to an endoscope inserted into a subject,
An excitation light source that emits excitation light having a wavelength region other than the visible light region;
An illumination light source that emits first illumination light having a wavelength region of visible light region;
A first optical surface on which the excitation light is incident; a wavelength conversion unit that converts the wavelength of the excitation light into second illumination light having a visible light wavelength range different from that of the first illumination light; and the first And having a second optical surface on which the first illumination light is incident and which reflects the second illumination light, the first illumination light and the second illumination light. Wavelength converting means for combining and emitting from the first optical surface;
An endoscope light source device comprising: supply means for supplying first and second illumination light emitted from the wavelength conversion means to the endoscope. The endoscope light source device according to claim 1, wherein the illumination light source is directly provided on a second optical surface of the wavelength conversion unit . The wavelength converting means is provided on a transparent substrate,
The endoscope light source device according to claim 1, wherein the illumination light source is provided on the second optical surface side of the wavelength conversion unit with the transparent substrate interposed therebetween. 4. The endoscope light source device according to claim 3, wherein the transparent substrate is provided with heat radiating means for radiating heat generated by the wavelength converting means .   The endoscope light source device according to claim 4, wherein the transparent substrate is a sapphire substrate that is transparent and has high thermal conductivity. Monitoring means for monitoring the light quantity of the first illumination light and the light quantity of the second illumination light;
Based on the results of the monitoring, by controlling the amount of the first and second illumination light, and characterized by comprising a heating prevention means for preventing heat generation in the wavelength conversion unit or the illumination light source The light source device for an endoscope according to any one of claims 1 to 5.   Color tone stabilization means for stabilizing the color tone of the illumination light including the first and second illumination lights by independently controlling the light quantity of the first illumination light and the light quantity of the second illumination light. The endoscope light source device according to any one of claims 1 to 6, further comprising: The wavelength conversion means is a green phosphor having an excitation wavelength band in the ultraviolet region,
The illumination light source is a semiconductor light source,
The first illumination light is light emitted from the semiconductor light source,
8. The endoscope light source device according to claim 1, wherein the second illumination light is green fluorescence excited and emitted from the green phosphor by the excitation light in an ultraviolet region. 9. .   9. The endoscope according to claim 8, wherein the endoscope is supplied with white light in which first illumination light including a blue band and a red band and second illumination light of green fluorescence are mixed. Light source device.   The endoscope is supplied with white light in which the first illumination light including the blue band and the red band and the second illumination light of green fluorescence are mixed, and the peak intensity in the blue band of the first illumination light is: The endoscope light source device according to claim 8, wherein the intensity of the green fluorescence is higher than a peak intensity in a red band of the first illumination light.

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