JP2014023630A - Light source unit and electronic endoscope apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To align more LEDs in an LED array, and to efficiently utilize light emitted by each LED.SOLUTION: A light source unit 13 comprises: an LED array 24 where a plurality of LEDs 31 are aligned; and a lens array 25. The lens array 25 is disposed between a light guide 22 and the LED array 24, and includes two types of lens parts 34 and 35 for condensing light of each LED 31 to an incident end face 22a of the light guide 22. The second lens part 35 is disposed adjacent to at least one or more of the first lens parts 34, and it has radius of curvature smaller than that of the first lens part 34.

Description

  The present invention relates to a light source unit using an LED as a light source and an electronic endoscope apparatus.

  In a light source unit of a conventional electronic endoscope apparatus, a xenon lamp is mainly used as a light source. This is because the emission spectrum of the xenon lamp is similar to that of natural light and has good color rendering. In addition, a longer life than a filament type lamp is one factor in using a xenon lamp. However, although it has a long life, a so-called ball breakage occurs even with a xenon lamp. If a ball break occurs during use of the electronic endoscope apparatus, observation must be interrupted or stopped, which imposes a great burden on the patient. Moreover, in order to prevent the observation interruption due to unexpected ball breakage, for example, it must be periodically replaced with a new one before the ball breakage occurs, which increases running costs.

  As is well known, LEDs have a longer lifetime than xenon lamps. An LED that emits white (or pseudo white) is also known. For this reason, when using an LED, the risk of running out of the bulb is lower than when using a xenon lamp, and the running cost can be reduced. However, the conventional white LED is insufficient in luminance for use in an electronic endoscope device, and is practically used. It was not reached.

  However, in recent years, high-intensity white LEDs have begun to appear, and it has become practical to replace xenon lamps with white LEDs. However, even if the white LEDs are becoming brighter, it is not possible to obtain a sufficient amount of light for observation from one (one chip) LED, so the high-brightness white LEDs are used as the light source for endoscopes. However, it is necessary to use an LED array in which a plurality of LEDs are arranged.

  Further, the electronic endoscope apparatus guides light from the light source unit into the subject by the light guide inserted into the endoscope main body, so that the light from each LED of the LED array is incident on the incident end face of the light guide. Must be incident. However, since the size of the entire LED array is usually larger than the incident end face of the light guide, the light from the LEDs arranged at an angle when viewed from the incident end face of the light guide remains as it is. It may not be incident on the end face well. For this reason, when an LED array is used for the light source unit, it is necessary to devise a method for efficiently making the light from each LED incident on the incident end face of the light guide.

  For example, an endoscope using an LED array in which each LED is arranged to be inclined toward the light guide in order to cause a light beam emitted from each LED of the LED array to enter the light guide is known (Patent Document 1). . Also, a microlens is formed on each LED, and the light is condensed on the light guide by the microlens (Patent Document 2), or the light flux of each LED is arranged by arranging each LED on the concave surface. A light guide (Patent Documents 3 and 4) is also known.

JP 2002-65604 A JP-A-5-146403 JP 2002-360514 A JP 2001-078961 A

  When an LED array is used as an endoscope light source, in order to allow the luminous flux of each LED to enter the light guide without waste, the luminous flux of all LEDs should be incident at an angle corresponding to the numerical aperture (NA) of the light guide. Is preferred. For this reason, the range in which the LEDs can be arranged is generally determined by the NA of the light guide.

  Moreover, since the light emission amount of each LED is small, a lens for condensing the light of each LED on the incident end face of the light guide must be provided as in Patent Document 2, for example, but sufficient light is collected from each LED. For this purpose, a relatively large lens is required as compared with the LED chip. For this reason, even if the arrangement interval of the LEDs is simply reduced to increase the number of LEDs used, the lenses physically interfere with each other and the effective diameter is sacrificed, so that it becomes difficult to obtain a necessary light amount. Sometimes. That is, it can be said that the minimum interval between the LEDs of the LED array is roughly determined by the required lens size.

  For these reasons, for example, when the LED array is close to the incident end of the light guide, the number of LEDs that can be used in the LED array is small, and even if a high-intensity white LED is used, the amount of light may be insufficient. On the other hand, in order to compensate for the shortage of light quantity due to the limitation on the number of LEDs arranged, it is necessary to separate the LED array from the incident end of the light guide and use more LEDs, and an increase in the size of the light source unit is inevitable. In particular, in a light source unit for an endoscope apparatus using an existing xenon lamp, when the xenon lamp is replaced with an LED array, the distance at which the LED array can be arranged with respect to the incident end face of the light guide can be arbitrarily extended. Since it is not possible, the LED array may not be replaced.

  Patent Documents 1 to 4 disclose a configuration for increasing the incident efficiency to the light guide on the premise that the light quantity necessary for endoscopic observation can be obtained by the number of LEDs in the LED array as described above. However, no mention is made of the above-mentioned problems and solutions.

  In the present invention, when the NA of the light guide and the distance from the incident end surface of the light guide to the LED array are predetermined values, more LEDs are arranged in the LED array and light emitted from each LED is efficiently used. The purpose is to make it possible.

  The light source unit of the present invention includes an LED array in which a plurality of LEDs are arranged, a first lens unit, and a second lens unit. The first lens unit is provided between the light guide and the LED array, and condenses light emitted from a predetermined LED of the plurality of LEDs on the incident end surface of the light guide. The second lens unit condenses the light emitted from the LED disposed adjacent to the LED corresponding to the first lens unit on the incident end surface, and is adjacent to the first lens unit at one or more locations, The radius of curvature is smaller than the part.

  The first lens unit and the second lens unit are an integrated lens array.

  It is preferable that the plurality of LEDs include white LEDs that emit white light.

  The white LED preferably includes an LED that emits excitation light and a phosphor that emits fluorescence when the excitation light passes through, and generates white light by the excitation light that has passed through the fluorescence and the phosphor.

  As the plurality of LEDs, it is preferable to have two types of LEDs, a large area LED having a large area and a small area LED having a small area.

  The large area LED is preferably disposed under the first lens portion, and the small area LED is preferably disposed under the second lens portion.

  The plurality of LEDs preferably include a narrowband light LED that emits a predetermined narrowband light.

  The narrowband light LED is preferably disposed under the second lens portion.

  The plurality of LEDs preferably include a white LED that emits white light and a single-color LED.

  The monochromatic LED is preferably disposed under the second lens portion.

  When the LED is not in front of the incident end face of the light guide, the first lens part and the second lens part are preferably arranged so as to be shifted from the position directly above the corresponding LED toward the center where the incident end face is located.

  The LEDs may be arranged in a straight line.

  The LEDs may be arranged two-dimensionally.

  The LEDs may be arranged in a concave shape with respect to the incident end face of the light guide.

  It is preferable that all the second lens parts are adjacent to at least one first lens part.

  The electronic endoscope apparatus of the present invention includes the above-described light source unit.

  According to the present invention, by using adjacent lens portions having different curvature radii, when the distance from the light guide NA and the light guide incident end surface to the LED array is a predetermined value, more LEDs are provided in the LED array. And the light emitted from each LED can be used efficiently.

It is an external view of an electronic endoscope apparatus. It is explanatory drawing which shows the structure of a light source unit. It is the top view and sectional drawing which show the structure of a LED array and a lens array. It is a graph which shows the directivity of LED. It is explanatory drawing which shows the outline | summary of simulation. It is a graph which shows the result of simulation. It is sectional drawing of the LED array and lens array of a comparative example. It is sectional drawing of the LED light source in the case of using LED using a fluorescent substance. It is a graph which shows the directivity of LED using a fluorescent substance. It is explanatory drawing which shows the structure of the electronic endoscope apparatus of a modification. It is a graph which shows the effect | action of a modification. It is sectional drawing of the LED light source in the case of using together LED from which an area differs. It is a graph which shows an effect | action at the time of using together LED from which an area differs. It is sectional drawing of the LED light source which used together LED using a fluorescent substance, and LED which does not use a fluorescent substance. It is a top view of an LED array and a microphone lens when LEDs are two-dimensionally arranged. It is sectional drawing of an LED array and a lens array in the case of arrange | positioning five LED one-dimensionally. It is sectional drawing of an LED array and a lens array in the case of arranging five LED chips two-dimensionally. It is a top view of an LED array and a lens array when three types of microlenses are used. It is explanatory drawing which shows the example which arranged LED on the concave surface. It is explanatory drawing which shows the example which deform | transformed the incident end surface of the light guide. It is explanatory drawing which shows the example which adjusted the position of the optical axis of each lens part in a peripheral part. This is an electronic endoscope apparatus in which a phosphor is disposed in front of an emission end face of a light guide. A light source unit using a rotary filter.

  As shown in FIG. 1, the electronic endoscope apparatus 10 includes an endoscope main body 11, a processor unit 12, a light source unit 13, a monitor 19, and the like.

  The endoscope body 11 includes an insertion unit 14, an operation unit 16, a universal cord 17, and the like. The insertion portion 14 is a portion that is inserted into the subject and is flexible. In addition, an imaging optical system such as a lens or a prism that forms an image on the imaging element of light incident through the imaging element and the imaging window is provided at the distal end 14 a of the insertion portion 14. The imaging element is a known type such as a CMOS type or a CCD type.

  On the end surface of the tip 14a, together with an imaging window, an illumination window for irradiating illumination light into the subject, a forceps outlet for projecting a treatment instrument such as a forceps, and air and water are jetted into the subject. Air supply / water supply ports are provided. A projection optical system for irradiating the entire field of view with illumination light guided from the light source unit 13 through a light guide (see FIG. 2) is provided behind the illumination window. The forceps outlet is an end of the forceps channel, and the other end of the forceps channel, which is a forceps insertion port, is provided in the operation unit 16.

  The operation unit 16 is provided at a proximal end portion of the insertion unit 14, and ejects air and water from an angle knob for bending the distal end 14a of the insertion unit 14 vertically and horizontally, and an air / water supply port. An air / water button for recording, a freeze button for recording a still image, a zoom button for instructing enlargement / reduction of an observation image to be displayed on the monitor 19, and the like are provided. In addition, a control circuit for controlling the operation of the image sensor is provided inside the operation unit 16.

  The endoscope body 11 is connected to the processor unit 12 and the light source unit 13 via a universal cord 17 and a connector 18 provided at an end of the universal cord 17. In the universal cord 17, a transmission cable for transmitting and receiving control signals and images to and from the processor unit 12 and a light guide are inserted.

  The processor unit 12 is electrically connected to the endoscope main body 11 and the light source unit 13 and comprehensively controls the operation of the electronic endoscope apparatus 10. For example, the processor unit 12 performs various image processing such as a DSP for imaging an imaging signal transmitted from the endoscope body 11 and electronic scaling, color enhancement processing, and edge enhancement processing on the captured image. A DIP or the like is provided. The processor unit 12 adjusts the amount of illumination light by controlling the operation of each part of the light source unit 13 by the light source driving unit 21 (see FIG. 2). The light source driving unit 21 is a control circuit for controlling the operation of each unit of the light source unit 13.

  The processor unit 12 is connected to the monitor 19. The monitor 19 displays an image captured by the endoscope main body 11, information on the subject, a setting screen for performing detailed settings for image processing performed by DIP, and the like.

  As shown in FIG. 2, the light source unit 13 includes a light guide 22 and an LED light source 23.

  The light guide 22 is a bundle of, for example, a plurality of optical fibers, and guides light incident on one end (incident end face 22a) with almost no loss and emits it from the other end. The incident end face 22a of the light guide 22 is exposed to the front (not necessarily the front) of the LED light source 23, and the light emitted from the LED light source 23 is incident thereon. The incident end face 22 a is substantially parallel to the LED light source 23. The shape of the incident end face 22a is, for example, a circle.

  The light guide 22 is connected to the light guide inserted through the endoscope body 11 by the connector 18. For this reason, when the endoscope main body 11 is connected to the light source unit 13, the emission end face (not shown) of the light guide 22 is at the distal end 14 a of the insertion portion 14. Light emitted from the exit end face of the light guide 22 is irradiated into the subject as illumination light through a projection optical system (not shown) such as a lens. The light projecting optical system may include an optical filter that transmits light in a predetermined wavelength band, a phosphor that generates fluorescence by light emitted from the light guide 22, and the like. For this reason, the color etc. may differ between the light which the light guide 22 guided and the illumination light irradiated in a subject. In this embodiment, the light emitted from the LED light source 23 is used as illumination light as it is.

  The angle (opening angle) of light that can be received from the incident end face 22a of the light guide 22 is a predetermined angle 2α, and NA is sin α. The aperture angles 2α and NA are determined in advance by the refractive indexes of the core and clad of the optical fiber forming the light guide 22. The diameter of the light guide 22 is about 1 mm, for example, and is smaller than the size W of the LED light source 23.

  The LED light source 23 includes an LED array 24 in which a plurality of LEDs 31 (see FIG. 3) are arranged in a predetermined arrangement, and a lens array 25 that condenses light emitted from each LED 31 of the LED array 24 on the incident end face 22a of the light guide 22. Etc. The lighting and extinction of each LED, the light emission amount, and the like are collectively controlled by the light source driving unit 21.

  In addition, the width (substantially effective diameter) W of the LED light source 23 and the arrangement distance D of the LED light source 23 with respect to the incident end face 22 a of the light guide 22 are restricted by the NA of the light guide 22. Specifically, the width W of the LED light source 23 and the distance D from the incident end face 22a are set so as to generally satisfy tan α ≦ W / 2D. If the width W and the arrangement distance D of the LED light source 23 are determined so as to be generally within this range, the light emitted from each LED of the LED array 24 is guided to the emission end face of the light guide 22. On the other hand, when the width W of the LED 23 is too large or the arrangement distance D is too close to the incident end face 22a, the light emitted from the LED 31 outside the NA of the light guide 22 is incident on the incident end face 22a by the lens array 25. May leak out of the light guide 22a and may not be guided to the exit end face.

  That is, when the LED light source 23 is arranged near the incident end face 22a according to the housing size of the light source unit 13, the width W of the LED light source 23 has to be reduced accordingly, so that it can be arranged in the LED array 24. The number of LEDs 31 is reduced. Further, in order to increase the amount of illumination light, the number of LEDs arranged in the LED array 24 may be increased. However, since the width W of the LED light source 23 is correspondingly increased, the arrangement distance D is accordingly increased. Must be bigger.

  Of course, when the material of the light guide to be used can be changed, or when the housing size of the light source unit 13 can be arbitrarily determined, the NA of the light guide 22, the width W of the LED light source 23, and the arrangement distance of the LED light source 23 In the following, the NA of the light guide 22, the width W of the LED light source 23, and the arrangement distance D are determined in advance according to the required amount of illumination light, the housing size of the light source unit 13, and the like. Shall.

  As shown in FIG. 3, the LED array 24 includes a plurality of LEDs 31 and a substrate 32 for driving these LEDs 31. In the present embodiment, the number of LEDs 31 is four, and they are arranged on the substrate 32 in a straight line at equal intervals. The four LEDs 31 are all the same, for example, are formed in a 1 mm square, and all emit light of the same predetermined wavelength band (for example, white light). The substrate 32 has a planar shape, is provided with wiring and the like (not shown) for driving the LEDs 31, and is connected to the light source driving unit 21.

  The lens array 25 is provided with two lens portions 34 and 35 adjacent to each other. The first lens unit 34 and the second lens unit 35 are microlenses that are hemispherical but have different radii of curvature. The lens array 25 has two first lens portions 34 and two second lens portions 35 so as to correspond to the four LEDs 31 respectively. Each of the four lens portions 34 and 35 condenses light from the LED 31 directly below the incident end face 22a. For example, in the light emitted from the LED 31 arranged second from the left in FIG. 3, the portion that has passed through the second lens part 35 provided second from the left is condensed on the incident end face 22a. A part of the light from the second LED 31 from the left enters the first lens part 34 provided so as to correspond to the LEDs 31 adjacent to the left and right, but even if it passes through the first lens part 34, the incident end face 22a. Is not collected.

  The radius of curvature R of the first lens unit 34 is such that when only one LED 31 is placed at the arrangement distance D, the light of the LED 31 can be collected most efficiently on the incident end face 22a of the light guide 22. The radius of curvature is determined based on the arrangement distance D of the LED light source 23 and the directivity of the LED 31. For example, the first lens unit 34 condenses the light emitted from the LED 31 just to the size of the incident end face 22a.

  On the other hand, the radius of curvature r of the second lens portion 35 is smaller than the radius of curvature R of the first lens portion 34 (R <r). For this reason, if the second lens unit 35 is used when only one LED 31 is placed at the arrangement distance D, for example, the focal point is focused in front of the incident end face 22a, and the position of the incident end face 22a is larger than the incident end face 22a. The light collection efficiency is inferior to the case where the first lens unit 34 is used. However, as will be described later, when the second lens unit 35 has a smaller radius of curvature than the first lens unit 34, a plurality of LEDs 31 are arranged and used adjacent to the first lens unit 34. The light collection efficiency to the incident end face 22a as the whole LED light source 23 is improved.

  In addition, the edge part (boundary part) of the adjacent 1st lens part 34 and the 2nd lens part 35 overlaps, and is integrated. For this reason, the lens array 25 is the whole of the four lens portions 34 and 35 connected and integrated. The end portions of the first lens portion 34 and the second lens portion 35 overlap each other because the LEDs 31 are arranged at an arrangement interval d equal to the radius of curvature R of the first lens portion 34 (d = R). ).

  As described above, the radius of curvature R is a radius of curvature for condensing light from one LED 31 to the incident end face 22a most efficiently when the LED light source 23 is placed at the arrangement distance D. When the light of the LED 31 is used without any waste, the first lens part 34 having the radius of curvature R is disposed on each LED 31 and the first lens part 34 of the LED 31 adjacent to the first lens part 34 is disposed. It must not overlap. For this purpose, the arrangement interval d of the LEDs 31 needs to be ½ times the radius of curvature R (d = R / 2), so that only two LEDs 31 can be arranged within the range of the width W. Specifically, in FIG. 3, the lens array 25 is formed by only the portion of the first lens 34 and only the LEDs 31 below the first lens portion 34 are arranged.

  In order to increase the amount of illumination light, the LED light source 23 further arranges two LEDs 31 from the state where only the two LEDs 31 can be arranged, and makes the arrangement interval d of the LEDs 31 equal to the curvature radius R. However, even if the number of LEDs 31 is simply added, the amount of illumination does not increase unless the light from the added LEDs 31 is collected on the incident end face 22a by the lens. Therefore, the second lens portion 35 is provided on the added LEDs 31. It is arranged.

Hereinafter, the operation of the electronic endoscope apparatus 10 configured as described above will be described. First, as shown in FIG. 4, it is assumed that the light emission amount of each LED 31 mounted on the LED light source 23 has a distribution of I ₁ (θ) proportional to cos θ. In this case, the light emission amount of each LED 31 is the maximum value I ₁ (0) in the Z direction, and the angle from the Z direction increases, and in the in-plane direction (X (or Y) direction) in which the LEDs 31 are arranged. As it approaches, the amount of light emission decreases. The light emission amount of the LED 31 is 0 in the in-plane direction (θ = 0).

  Further, as described above, the LED light source 23 actually mounted on the electronic endoscope apparatus 10 includes four LEDs 31. Here, in order to clarify the principle and operation, as shown in FIG. In the simplest case, two LEDs 31 are arranged, and the first lens portion 34 is disposed on one LED 31 and the second lens portion 35 is disposed on the other LED 31. The curvature radius R of the first lens portion 34 is a fixed value determined by the arrangement distance D of the LED light source 23 with respect to the incident end face 22a, and the curvature radius r of the second lens portion 35 is equal to the curvature radius R equal to the first lens portion 34. While gradually decreasing, the amount of light S1 collected by the first lens unit 34, the amount of light S2 collected by the second lens unit 35, and the total amount of light S1 + S2 collected from the two LEDs 31 onto the incident end face 22a. Was obtained by simulation.

As shown in FIG. 6, when the radius of curvature r of the second lens unit 35 is linearly decreased, the amount of light collected S2 by the second lens unit 35 decreases linearly, but the amount of light collected by the first lens unit 34 is S1. Increases according to the sin function. Therefore, the total light amount S1 + S2 collected from the two LEDs 31 by the first lens unit 34 and the second lens unit 35 is r≈0.518 [R / d] and a maximum value 1.12 | I ₁ |. there were. The unit of the radius of curvature r of the second lens unit 35 is R / d so that it does not depend on the specific size of the arrangement interval d of the LEDs 31. Further, the light amounts S1, S2, S1 + S2 are based on the normalized light emission amount | I ₁ | = ∫I ₁ (θ) dθ / I ₁ (0) of the LED 31.

As can be seen from FIG. 6, when the arrangement interval of the LEDs 31 is d, the curvature radius r of the second lens portion 35 is made equal to the curvature radius R of the first lens portion 34 (r = 1.0 [R / d]). The total light amount S1 + S2 is 1.0 | I ₁ |, and even though two LEDs 31 are arranged, only the light amount of one LED 31 is collected on the incident end face 22a. When only the first lens portion 34 is provided and the second lens portion 35 is not provided (r = 0.0 [R / d]), only the light from the LED 31 provided with the first lens portion 34 is collected. The total light amount S1 + S2 is 1.0 | I ₁ |. However, if the radius of curvature r of the second lens portion 35 is 0.518 R / d, the number of LEDs 31 can be increased.

  That is, when the LEDs 31 are arranged at the arrangement interval d (= R) and the first lens part 34 having the curvature radius R is arranged on one side, the curvature radius r of the other second lens part 35 is set to the first lens part 34. The amount of light that can be condensed on the incident end face 22a of the light guide 22 (that is, the amount of illumination light) can be increased by making it smaller than the radius of curvature. The above-described results shown in the two adjacent lens portions 34 and 35 are the same when there are a plurality of adjacent portions by arranging a plurality of lens portions 34 and 35.

  Therefore, as shown in FIG. 7A, when four LEDs 31 are arranged at the arrangement interval d and the first lens portions 34 having the curvature radius R are arranged on all the LEDs 31, or as shown in FIG. 7B. As described above, the large and small lens portions 34 and 35 used in the electronic endoscope apparatus 10 are compared with the case where only every other four LEDs 31 are arranged so that there is no defect due to the overlapping of the lens portions. The arranged LED light sources 23 can increase the amount of condensed light and the amount of illumination light on the incident end face 22a.

  Further, the condition that the arrangement interval of the LEDs 31 is set to d = R is that the arrangement of the LEDs 31 is more than that in the case where the LEDs 31 are arranged so that the ends of the first lens portions 34 having the radius of curvature R do not overlap (d = R / 2). Although the number is increased, the condition for arranging the LEDs 31 so that the ends of the first lens portions 34 having the radius of curvature R do not overlap is that the LEDs 31 below the second lens portions 35 in FIG. This corresponds to the case where the second lens portion 35 is not provided (r = 0.0 [R / d] in FIG. 7B and FIG. 6). For this reason, in the LED light source 23 in which the large and small lens portions 34 and 35 used in the electronic endoscope apparatus 10 are arranged, the arrangement number of the LEDs 31 is increased, and the large and small lens portions 34 are arranged on the adjacent LEDs 31. As a result, the amount of light collected on the incident end face 22a and the illumination are reduced as compared with the case where the number of LEDs 31 is reduced in order to arrange the first lens portions 34 having a radius of curvature R so that there is no overlap defect on all the LEDs 31. The amount of light can be increased.

  In the above-described embodiment, the xenon lamp of the conventional light source unit is used as the LED light source 23 as can be understood from the fact that the arrangement distance D and the width W of the LED light source 23 are set to predetermined values according to the NA of the light guide 22. It is also suitable for replacement. For example, it is possible to secure the amount of illumination light while matching the position distance D of the xenon lamp and the width W of the xenon lamp arrangement space.

  In the above-described embodiment, two first lens portions 34 and two second lens portions 35 are alternately arranged for four LEDs 31, but the second lens portion 35 is adjacent to the first lens portion 34. If there is at least 1 or more, the above-described effect can be obtained. The same applies when two or three LEDs 31 are used or when five or more LEDs 31 are arranged.

  In the above-described embodiment, the arrangement interval d of the LEDs 31 is set equal to the curvature radius R of the first lens unit 34, but the arrangement interval d is arbitrary. However, when the light emission amount of the LED 31 is a predetermined value, in order to increase the illumination light amount of the electronic endoscope apparatus 10, it is necessary to increase the number of LEDs 31 arranged, so that the range of d> R / 2 is satisfied. Is optional.

  The specific configuration of the LED 31 is arbitrary. For example, as in the LED light source 40 shown in FIG. 8, an LED 31 that generates monochromatic light having a predetermined wavelength is replaced with an LED 41 that generates excitation light and an excitation light. Alternatively, it may be formed with a phosphor 42 that absorbs the portion and emits fluorescence of a predetermined wavelength band. For example, if the excitation light LED 41 emits purple to blue light and the phosphor 42 emits green to yellow fluorescence, the fluorescence generated in the phosphor 42 and the excitation light transmitted through the phosphor 42 Are combined to generate pseudo white light.

As described above, when the LED 31 of the above-described embodiment is formed by the excitation light LED 41 and the phosphor 42, as shown in FIG. 9, the light amount distribution (directivity) of the excitation light is the LED 31 of the above-described embodiment ( Although I ₁ (θ) = cos θ, which is the same as that in FIG. 4, the fluorescence light quantity distribution I ₂ (θ) has a maximum in the θ = 45 ° direction. This is due to the balance between the light amount distribution I ₁ (θ) of the excitation light and the length of the excitation light transmitted through the phosphor 42. Therefore, when the excitation light LED 41 and the phosphor 42 are used as the LED 31, the curvature radius r of the second lens portion 35 is set in consideration of the light quantity distributions I ₁ (θ) and I ₂ (θ) of FIG. Must be calculated.

  In the above-described embodiment, all the LEDs 31 arranged in the LED array 24 are uniformly controlled. However, the LED 31 under the first lens unit 34 and the LED 31 under the second lens unit 35 are individually assembled into separate sets. You may control. In this case, for example, as shown in FIG. 10, the LED 31 under the first lens unit 34 is turned on / off, and the first light source driving unit 46 that controls the amount of light, and the LED 31 under the second lens unit 35 is turned on / off. And a second light source driving unit 47 for controlling the light quantity is provided in the processor unit 12.

  Then, as shown in FIG. 11, in the range E1 where the illumination light quantity is small, the LED 31 below the second lens unit 35 is turned on, and the illumination light quantity is adjusted by the light quantity S2 by controlling the drive current. In the range E1, the LED 31 below the first lens unit 34 is turned off. Next, in the range E2 where the amount of illumination light is medium, the LED 31 below the second lens unit 35 is turned off, the LED 31 below the first lens unit 34 is turned on, and the drive current is controlled to control the illumination with the light amount S1. Adjust the light intensity. In the range E3 where the amount of illumination light is large, the LED 31 under the first lens unit 34 is lit with the maximum drive current, and further the drive current of the LED 31 under the second lens unit 35 is adjusted to obtain the light amount S1 (maximum). The illumination light quantity is adjusted by the total of the light quantity S2 (variable).

  The drive current range G1 that can drive the LED 31 with good color rendering is substantially determined by the area of the LED 31, and the color of the light emitted by the LED 31 may change when driven by a drive current smaller than the predetermined range G1. . Further, when the LED 31 is driven with a large drive current exceeding the predetermined range G1, the LED 31 may be damaged due to heat generation or the like. For this reason, as shown by a two-dot chain line in FIG. 11, when all the LEDs 31 of the LED array 24 are uniformly controlled at the same time, the desired color is substantially only in the middle of the predetermined range G1 range E2 to the range E3. The illumination light quantity range is about R0. On the other hand, as described above, if the LED 31 under the first lens unit 34 and the LED 31 under the second lens unit 35 are divided into groups, and lighting / extinguishing and light quantity are controlled separately in each group, the drive current is predetermined. While controlling within the range G1, the range of the illumination light quantity can be expanded to R1.

  In FIG. 11, in each range of E1 to E3, the light amount is adjusted by adjusting the drive current of either the LED 31 below the first lens portion 34 or the LED 31 below the second lens portion 35. However, the LED 31 below the first lens unit 34 and the LED 31 below the second lens unit 35 are not divided in any range without performing such range division by turning on / off each group. May be lit together and the amount of illumination light may be adjusted by adjusting the amount of light emitted from each of these groups.

  In the above-described embodiment, the LEDs 31 arranged in the LED array 24 are all the same, but a plurality of types of LEDs may be used. For example, as in the LED light source 50 shown in FIG. 12, the LED 51 under the first lens unit 34 may be an LED 51 with a large area, and the LED under the second lens unit 35 may be an LED 52 with a small area.

  As the area of the LED is larger, the LED can be driven with a larger current, and a larger amount of light can be obtained. On the other hand, the smaller the LED area, the smaller the amount of light emitted, but a desired color can be obtained even with a low drive current. For this reason, as shown in FIG. 13, in the range E1 ′, the illumination light amount is adjusted by the light amount S2 from the small area LED 52 below the second lens portion 35, and in the range E2 ′, the light amount from the large area LED 51 below the first lens portion 34. The amount of illumination light is adjusted by S1. In the range E3 ', the amount of illumination light is adjusted by adjusting the drive current of the small area LED 52 below the second lens unit 35 while driving the large area LED 51 below the first lens unit 34 with the maximum drive current.

  In this way, as shown by the two-dot chain line, all the LEDs 31 are made the same, and a desired color can be obtained for each of the large area LED 51 and the small area LED 52 as compared with the range R0 of the illumination light quantity when uniformly controlled. While driving in the drive current range G1, G2, the range of illumination light quantity can be expanded to R1. In particular, as described above, the maximum amount of illumination light is reduced as compared with the case where the first LED unit 34 and the second lens unit 35 are separately driven while using the same LED 31 (see FIG. 11). However, it is possible to extend the range of the illumination light amount for obtaining a desired color in a range where the illumination light amount is small.

  In FIG. 12, the large area LED 51 is disposed under the first lens portion 34 and the small area LED 52 is disposed under the second lens portion 35, but conversely, the small area LED 51 is disposed under the first lens portion 34. The LED 52 may be disposed, and the large area LED 52 may be disposed under the second lens portion 35. However, as can be seen from FIG. 6 described above, if the LEDs are the same, the amount of light S1 collected by the first lens unit 34 and the amount of light S2 collected by the second lens unit 35 have a large curvature radius. Since the amount of light collected by the one lens unit 34 is larger (S1> S2), the large area LED 51 is arranged below the first lens unit 34 and the small area LED 52 is arranged below the second lens unit 35 as shown in FIG. The light collection efficiency is better. If arranged in reverse, the first lens unit 34 capable of condensing a large amount of light can condense only a small amount of light generated from the small area LED 52 and the second lens unit 35 can condense only a small amount of light. This is because the loss of the amount of light is large.

  In FIG. 12, the LEDs 51 and 52 arranged in the LED light source 50 are formed by the excitation light LED 41 and the phosphor 42. However, the LEDs 51 and 52 do not use the phosphor 42 together with the LED 31 of the embodiment. An LED may be used.

Further, like the LED light source 60 of FIG. 14, an LED 51 having an excitation light LED 41 and a phosphor 42 is disposed under the first lens portion 34, and an LED 53 that does not use a phosphor is disposed under the second lens portion 35. It may be arranged. As shown in FIG. 14, when the LED 51 using the phosphor and the LED 53 not using the phosphor are used in combination, the LED 51 using the phosphor is disposed under the first lens unit 34, and the second lens unit 52 is disposed below. It is preferable to arrange an LED 53 that does not use a phosphor. This is because, in the case of the LED 51 using a phosphor, the light quantity distribution I ₂ (θ) of the generated fluorescence is inclined (see FIG. 9), so that the light is collected from a wide angle in order to sufficiently collect the fluorescence. It is preferable to use the possible first lens unit 34. In the case of the LED 53 that does not use fluorescence, the local maximum point of the light amount distribution I ₁ (θ) is in the Z direction (see FIG. 4) and is narrower by the second lens unit 35. This is because it is possible to collect a relatively large amount of light as compared to fluorescence only by collecting light in the angle range.

  Furthermore, as shown in FIG. 14, when the LED 51 using the phosphor and the LED 53 not using the phosphor are used in combination, the LED 51 using the phosphor is white (pseudo) if the amount of illumination of white light used for normal observation is insufficient. It is preferable that the LED 53 for white band) and the LED 53 not using a phosphor be a narrow band light LED. An LED for narrow band light is an LED that generates, for example, blue narrow band light (about 390 to 445 nm) or green narrow band light (530 to 550 nm), and emphasizes a blood vessel and a pit pattern of a subject. This is an LED for observing so-called special light. As described above, when the narrowband light LED 53 is disposed under the second lens unit 35, the first lens unit 34 and the second lens unit 35 are provided in the lens array 25 even when the LED light source 23, which tends to have insufficient light amount, is used. Since the amount of light can be compensated for by this, it is possible to easily switch between normal observation with white light and special light observation with narrow-band light.

  Of course, even when special light observation can be performed, it is not necessary that all the LEDs arranged under the second lens portion 35 be special light LEDs, and at least one of them may be special light LEDs. In addition, when there are a plurality of second lens portions 35, some of the LEDs arranged below the second lens portion 35 may be blue narrow-band light LEDs, and others may be green narrow-band light LEDs. Furthermore, when there is sufficient white light, not only the LED arranged under the second lens unit 35 but also a part of the LED arranged under the first lens unit 34 may be a special light LED. .

  Further, instead of the LED 53 not using a phosphor as a special light LED, any of RGB (or a complementary color YMC) or any color mixture of these may be used. As described above, in FIG. 14, if an LED emitting RGB is used as the LED 53 that does not use a phosphor, and these are turned on together with the LED 51 under the first lens portion 34, the color rendering property of the illumination light can be improved. . Thus, when using LED which generate | occur | produces RGB etc. for LED53, it is not necessary to make it LED of the same color to all LED under the 2nd lens part 35, and RGB should just be arrange | positioned in a required ratio.

  In the above-described embodiment, the LED light source 23 linearly arranges four LEDs, but the LEDs of the LED light source 23 may be arranged two-dimensionally. For example, as shown in FIG. 15, the LEDs 31 may be arranged in a square shape. In this case, since the first lens unit 34 and the second lens unit 35 are adjacent to each other in two directions (X direction and Y direction) in the plane in which the LEDs 31 are arranged, the radius of curvature r of the second lens unit 35 is as shown in FIG. However, the calculation method is the same as that of the above-described embodiment. In addition, since the diagonal length of the first lens portion 34 is longer than the diagonal length of the two second lens portions 35, the width W of the LED light source in FIG. Is the length in the diagonal direction.

  In the above-described embodiment, four LEDs are used for the LED light source 23. However, the number of LEDs arranged in the LED light source 23 is arbitrary as long as it is two or more. For example, as shown in FIG. 16, five LEDs 31 may be arranged in the LED light source 23. In FIG. 16, three first lens portions 34 are used and two second lens portions 35 are used therebetween. However, three second lens portions 35 are used and the first lens portion 34 is used therebetween. May be. Further, in FIG. 3 and FIG. 16, the first lens unit 34 and the second lens unit 35 are alternately arranged. However, the first lens unit 34 and the second lens unit 35 are not necessarily arranged alternately. good. As can be seen from the description of FIG. 6, if there is at least one location where the first lens portion 34 and the second lens portion 35 are adjacent to each other in the lens array 25, the first lens portion 34 and the second lens portion. The arrangement of 35 is arbitrary. Specifically, when five LEDs 31 and lens units 34 and 35 are used as shown in FIG. 16, the first lens unit 34, the second lens unit 35, the first lens unit 34, the first lens unit 34, A lens part may be provided like the first lens part 34. Of course, when the first lens portions 34 and the second lens portions 35 are alternately arranged and all the lens portions 34 and 35 are adjacent to the lens portions 34 or 35 having different radii of curvature, the light quantity improvement effect is greatest. .

  What is necessary is just to provide two or more LED31 and the lens parts 34 and 35, also when arranging LED31 and the lens parts 34 and 35 two-dimensionally. For example, as shown in FIG. 17, when five LEDs 31 are two-dimensionally arranged, the second lens unit 35 is used on the central LED 31 and the first lens unit 34 is used on the four surrounding LEDs 31. It ’s fine. Of course, the first lens unit 34 may be disposed on the central LED 31 and the second lens unit 35 may be disposed on the four surrounding LEDs 31. Further, as described above, if the first lens portion 34 and the second lens portion 35 are adjacent to each other at least at one place, there is an effect of improving the light amount. Therefore, at least one first lens portion 34 and two second lens portions 35 are provided. The number and arrangement of the first lens portion 34 and the second lens portion 35 are arbitrary, except that they must be used adjacent to each other.

Further, in the above-described embodiment, two types of lens portions are used, that is, the first lens portion 34 having the curvature radius R and the second lens portion 35 having the curvature radius r (<R), but as in the LED light source 70 of FIG. The lens array 25 may use large, medium, and small lens portions 71, 72, and 73 (curvature radius r ₁ > r ₂ > r ₃ ). In this case, as shown in FIG. 6, there is an effect of improving the light amount in the relationship between the large and middle lens portions 71 and 72 or in the relationship between the small and medium lens portions 72 and 73. In FIG. 18, the lens portions are arranged in the order of large, medium and small, but the lens portions may be arranged in the order of large and small. Similarly, when two-dimensionally arranging LEDs and lens units, three or more types of lens units having different radii of curvature may be used. Further, in FIG. 18, three types of lens portions having different radii of curvature are used for the lens array 25, but four or more types of lens portions having different radii of curvature may be used.

  In the above-described embodiment, the LEDs 31 are arranged in a planar shape, but the LEDs 31 may be arranged on a curved surface that is concave on the light guide 22 side, as in the LED light source 80 of FIG. As described above, when the LEDs 31 are arranged in a concave shape, the optical axes of the lens portions 34 and 35 are directed to the incident end face 22a by the curvature of the concave face, so that the light of each LED 31 is more easily condensed on the incident end face 22a.

  In the above-described embodiment, the shape of the incident end face 22a of the light guide 22 is circular, but the shape of the incident end face 22a is arbitrary. For example, like the light guide 97 shown in FIG. 20, the shape of the incident end surface 97a is such that the longitudinal direction of the LED light source 23 has a long diameter and the short direction has a short diameter according to the overall shape of the LED light source 23. May be oval. When the LEDs 31 are arranged in a horizontal row as in the LED light source 23, the cross-sectional shape of the light beam emitted from the LED light source 23 as a whole is a shape close to an ellipse, so that the overall light flux of the LED light source 23 is as described above. If the incident end face shape is set in accordance with the shape, the light flux of the LED light source 23 is easily incident even with a light guide having the same NA. The same applies when the LEDs 31 are two-dimensionally arranged. Here, the incident end face 97a is elliptical, but the incident end face 97a may be oval (stadium type), rectangular, or the like.

Instead of arranging the LED 31 in a curved manner as described above, as shown in FIG. 21, the lens portions 34 and 35 on the LED 31 at a position shifted from the front surface of the incident end surface 22a are connected to the incident end surface 22a side (the front surface of the incident end surface 22a is You may arrange | position by shifting suitably in a certain center direction). In this way, the converging optical axis (indicated by the alternate long and short dash line) by the lens portions 34 and 35 on the LED 31 at a position shifted from the front surface of the incident end face 22a can be tilted toward the incident end face 22a. Is more easily collected on the incident end face 22a. However, the shift amount of the first lens unit 34 [delta] ₁ and the shift amount [delta] ₂ of the second lens unit 35 is not necessarily the same value. For example, when the curvature radius R of the first lens unit 34 and the curvature radius r of the second lens unit 35 are uniform regardless of the position of the incident end face 22a, the condensing optical axis of the first lens unit 34 and the second lens unit 35 are uniform. It is necessary to satisfy δ ₁ > δ ₂ in order to make the condensed optical axes of Of course, instead of changing the shift amounts δ ₁ and δ ₂ in the peripheral portions of the lens portions 34 and 35, the curvature radii R and r of the lens portions 34 and 35 in the peripheral portion with respect to the curvature radii R and r of the central portion. May be changed. In FIG. 21, for the sake of convenience, a large number of LEDs 31 are arranged, but the optical axes of the lens portions 34 and 35 located at positions shifted from the front surface of the incident end face 22a as described above are incident regardless of the number of LEDs 31. It is preferable to displace the end face 22a.

  In the above-described embodiment and modification, the light generated by the LED light source is irradiated as it is into the subject as illumination light. As shown in FIG. 22, for example, the phosphor 91 is excited from the LED light source 23. Excitation light is generated and allowed to pass through the phosphor 91 disposed in front of the light emitting end face of the light guide 22 at the tip end portion 14a, thereby generating white light by the propensity of the transmitted excitation light and the phosphor 91, and projecting optics The object may be irradiated as illumination light through the system 92.

  Further, as shown in FIG. 23, the LED light source 23 generates white light, and a rotatable rotary filter 93 in which a plurality of color filters are arranged between the light guide 22 and the LED light source 23 is arranged, whereby the LED light source Alternatively, light having a wavelength that is transmitted by each color filter from the white light generated at 23 may be selectively used as illumination light. The number and type of color filters provided in the rotary filter are arbitrary. For example, RGB (or complementary color) color filters, white filters that transmit white light, and narrow bands that transmit narrow band light for special light observation A filter or the like can be provided.

  Further, a lens (or a lens system composed of a plurality of lenses), a rod integrator, or the like is further disposed between the LED light source 23 and the light guide 22, and the light generated by the LED light source 23 is condensed on the incident end face 22a. You may make it easy.

  In the above-described embodiment and modification, the lens array 25 having the hemispherical lens portions 34 and 35 is provided on the LED integrally with the LED array 24, but the lens array 25 is provided separately from the LED array 24. It may be done. When the lens array 25 is provided separately from the LED array 24, the lens portions 34 and 35 may have curved surfaces on the light guide 22 side and the LED array 24 side. In this case, that the curvature radii of the lens portions 34 and 35 are small (or large) is a size compared on the same side surface. That is, when comparing the curvature radii of the surfaces of the first lens portion 34 and the second lens portion 35 on the light guide 22 side, the curvature radius of the second lens portion 35 is smaller than the curvature radius of the first lens portion 34. The same applies to the LED array 24 side. However, the radius of curvature of the second lens portion 35 does not have to be smaller than the radius of curvature of the first lens portion 34 on both sides, and at least on one side of the light guide 22 side and the LED array 24 side. What is necessary is just to enter smaller than the curvature radius of the 1 lens part 34. FIG.

  Furthermore, in the above-described embodiments and modifications, the lens portions 34 and 35 of the lens array 25 are spherical surfaces, but the lens portions 34 and 35 may be aspherical surfaces.

  In addition, although the example using LED was demonstrated in the above-mentioned embodiment and various modifications, other semiconductor light sources, such as LD, may be used instead of LED.

  In the above-described embodiment and various modifications, the curvature radius R of the first lens portion 34 is a fixed value determined by the arrangement distance D of the LED light source 23 with respect to the incident end face 22a. Even when D is a predetermined value, the radius of curvature R may be a variable value. Specifically, the radius of curvature of the first lens unit 34 may be R ′ (R ′ <R), and the radius of curvature r ′ of the second lens unit 35 may be determined according to the radius of curvature R ′. When the radius of curvature R of the first lens unit 34 is set to a fixed value determined by the arrangement distance D, an appropriate radius of curvature r (<R) of the two lens units 35 depends on the specific arrangement interval d of the LEDs 31 and the directivity of the LEDs 31. ) May not be required. In such a case, if the radius of curvature R ′ of the first lens portion 34 is made smaller than the radius of curvature R as described above, the curvature of the second lens portion 35 is obtained. The radius r ′ (<R ′) can be determined.

  In the above-described embodiment and various modifications, the LEDs arranged in the LED array 24 are square, but the shape of the LEDs is arbitrary. The LED may be rectangular or hexagonal. When the shape of the LED is rotationally asymmetric, such as when using a rectangular LED, the shape of the lens portions 34 and 35 may be modified (for example, elliptical) in accordance with this. Moreover, you may use LED from which multiple types of shapes differ.

  In addition, the above-mentioned embodiment and various modifications can be combined arbitrarily. For example, when the large area LED 51 and the small area LED 52 are used (see FIG. 12), the small area LED 52 may be an excitation light LED or an LED emitting RGB (see FIG. 14). In various LED arrangement methods (see FIGS. 3 and 15 to 19), LEDs using phosphors may be used (see FIG. 8), or LEDs having different areas may be used in combination. (See FIG. 12) A white LED and a monochromatic LED may be used together (see FIG. 14). Furthermore, in these arbitrary patterns, the LEDs may be arranged in a concave shape (see FIG. 19), the optical axes of the lens portions 34 and 35 may be shifted (see FIG. 21), and the LEDs are made concave. After the arrangement, the optical axes of the lens portions 34 and 35 may be further shifted.

  In addition, although description was abbreviate | omitted in the above-mentioned embodiment, the LED light source 23 may be equipped with various well-known members required for the LED light source 23, such as a heat sink for cooling the heat when the LED 31 emits light. good.

DESCRIPTION OF SYMBOLS 10 Electronic endoscope apparatus 11 Endoscope main body 12 Processor unit 13 Light source unit 22 Light guide 23, 40, 50, 60, 70, 80 LED light source 24 LED array 25 Lens array 31 LED
34 1st lens part 35 2nd lens part

Claims (16)

An LED array in which a plurality of LEDs are arranged;
A first lens unit provided between a light guide and the LED array, and condensing light emitted from a predetermined LED of the plurality of LEDs on an incident end surface of the light guide;
The light emitted from the LED disposed adjacent to the LED corresponding to the first lens portion is condensed on the incident end surface, and adjacent to the first lens portion at one or more locations, the first lens A second lens portion having a smaller radius of curvature than the portion;
A light source unit comprising:   The light source unit according to claim 1, wherein the first lens unit and the second lens unit are an integrated lens array.   The light source unit according to claim 1, wherein the plurality of LEDs include white LEDs that emit white light.   The white LED has an excitation light LED that emits excitation light and a phosphor that emits fluorescence when the excitation light passes through, and generates the white light by the excitation light that has passed through the fluorescence and the phosphor. The light source unit according to claim 3.   The light source unit according to claim 1, wherein the plurality of LEDs include two types of LEDs, a large area LED having a large area and a small area LED having a small area.   The light source unit according to claim 5, wherein the large area LED is disposed under the first lens portion, and the small area LED is disposed under the second lens portion.   The light source unit according to claim 1, wherein the plurality of LEDs include a narrowband light LED that emits predetermined narrowband light.   The light source unit according to claim 7, wherein the narrowband light LED is disposed under the second lens portion.   The light source unit according to claim 1, wherein the plurality of LEDs include a white LED that emits white light and a monochromatic LED.   The light source unit according to claim 9, wherein the monochromatic LED is disposed under the second lens unit.   When the LED is not in front of the incident end face of the light guide, the first lens portion and the second lens portion are arranged so as to be shifted in the central direction where the incident end face is located from directly above the corresponding LED. The light source unit according to claim 1.   The light source unit according to claim 1, wherein the LEDs are arranged in a straight line.   The light source unit according to claim 1, wherein the LEDs are arranged two-dimensionally.   The light source unit according to any one of claims 1 to 13, wherein the LEDs are arranged in a concave shape with respect to an incident end face of the light guide.   The light source unit according to claim 1, wherein all the second lens portions are adjacent to at least one of the first lens portions.   An electronic endoscope apparatus comprising the light source unit according to claim 1.

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