Abstract:
A light source device for an endoscope is provided. The light source device comprises a light source unit that supplies illumination light to an incident end face of a light guide member, which is laid inside an endoscope. The light source unit comprises a plurality of reflecting board members. Each reflecting board member has at least one light emitting diode. The plurality of reflecting board members are assembled into a concaved open polyhedron, so that the light emitted from the light emitting diodes are concentrated onto the incident end face of the light guide member.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a light source device for an endoscope. 
   2. Description of the Related Art 
   An endoscope comprises an insertion portion that is inserted into a digestive organ of a human body and the like. From the distal end of the insertion portion, illumination light is emitted. A light guide which is comprised of glass fibers is inside the endoscope. One end of the light guide is optically connected to a light source of an exclusive light source device. The other end of the light guide is positioned at the distal end of the insertion portion. Although a xenon lamp, a halogen lamp, and so forth are generally used for the light source, in recent years, light emitting diodes or LEDs may be utilized as the light source. 
   An LED has superior characteristics, such as a miniature size, a small amount of wasted electricity, and little heat generation. However, an LED is inferior in terms of the amount of luminescence and beam spread. 
   SUMMARY OF THE INVENTION 
   An object of the present invention is to provide a light source unit for an endoscope that can be assembled in a simple manner. 
   According to the present invention, a light source device for an endoscope is provided that comprises a light source unit that supplies illumination light to an incident end face of a light guide member which is inside the endoscope. 
   The light source unit is an assembly of a plurality of reflecting board members that have light reflecting sides, and each of the plurality of reflecting board members comprises at least one light emitting diode. 
   Further, according to the present invention, a method for fabricating a light source unit is provided that comprises following first to fifth steps. 
   The first step is to cutout a board member from synthetic resins. The board member is cutout so as to form a pre-assembly shape or a development for a concaved open polyhedron. The second step is to form a reflecting layer on one side of the board member. The third step is to mount a plurality of light emitting diodes onto the board member on the side on which the reflecting layer is formed. The forth step is to assemble the board member into the concave open polyhedron. The fifth step is to electrically wire the light emitting diodes from the side of the board member which is opposite to the reflecting layer. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The objects and advantages of the present invention will be better understood from the following description, with reference to the accompanying drawings in which: 
       FIG. 1  illustrates a light source device of the present embodiment of the invention together with an endoscope; 
       FIG. 2  is a pre-assembly shape or a development of the light source unit viewed from the side from which light is emitted; 
       FIG. 3  shows a side view of the assembled light source unit along the line III—III in  FIG. 2 ; 
       FIG. 4  is a plan view of another example of the light source unit; 
       FIG. 5  is a pre-assembly shape or a development of another example of the light source unit; 
       FIGS. 6A and 6B  are a cross sectional side view of another example of light source unit which is fabricated in different processes; 
       FIG. 7A  is a plan view of another example of a light source unit which is fabricated in different processes; and 
       FIG. 7B  is a cross sectional side view of the light source unit shown in FIG.  7 A. 
   

   DESCRIPTION OF THE PREFERRED EMBODIMENTS 
   The present invention is described below with reference to the embodiments shown in the drawings. 
     FIG. 1  illustrates a light source device of the present embodiment together with an endoscope. A light guide member  12  (indicated by a broken line in the figure) which is comprised of a plurality of glass fibers is inside the endoscope  10 . One end of the light guide member  12  is optically connected to the light source unit  30  of the light source device  20 , and the other end is positioned at the distal end of the insertion portion  14  of the endoscope. Note that, the light source unit  30  is arranged so that the center axis of the light source unit  30  coincides with the axis of the incident end face of the light guide member  12 . 
   The light source device  20  comprises the light source unit  30  that includes a plurality of LED&#39;s which radiate white light, a power source  22  for supplying electric power to each LED, and an LED drive circuit  24  that controls the emission of each LED. Note that, in  FIG. 1 , although the LED drive circuit  24  is separated from the light source unit  30 , the LED drive circuit  24  may be integrally built into the light source unit  30 . 
     FIG. 2  is a pre-assembly shape or a development of the light source unit  30  viewed from the side from which light is emitted.  FIG. 3  shows a side view of the assembled light source unit  30  along the line III—III in FIG.  2 . The light source unit  30  may comprise seven reflecting board members  101 ,  102 ,  103 ,  104 ,  105 ,  106 , and  107 . Each of the reflecting board members  101  to  107  is comprised of a flat plate, and the light source unit  30  is an assembly of the reflecting board members  101 - 107 . The first reflecting board member  101  that is positioned at the center of the unit  30  is formed as a regular hexagon shape with the side length L 1 . Each of the remaining six reflecting board members, or the second to seventh reflecting board members  102  to  107 , is connected to each side of the first reflecting board member  101 . Each reflecting board member  102 - 107  has an equivalent trapezoid shape with respect to one another. A top side (upper base) length of the each of the second to seventh reflecting board members  102 - 107  is equal to the side length L 1  of the first reflecting board member  101 . A bottom side (lower base) length L 2  of each of the second to seventh reflecting board members  102 - 107  is defined in consideration of the inclined angle of each of the assembled second to seventh reflecting board members  102 - 107  with respect to the first reflecting board member  101 . Note that, the inclined angle of each of the second to seventh reflecting board members  102 - 107  is defined in accordance with distance between the incident end face of the light guide member  12  and the light source unit  30 , so that the entire light from the LED&#39;s is concentrated on the incident end face of the light guide member  12  when the LED&#39;s are mounted on the unit in the manner detailed afterward. 
   The first to seventh reflecting board members  101 - 107  may comprise synthetic resins. One side of each of the reflecting board members  101 - 107  is formed with a reflecting layer  101   a - 107   a  by a plating process or the like. Note that, in  FIG. 3 , only the reflecting layers  101   a ,  104   a , and  107   a  are shown. At the substantially the center of each of the reflecting board members  101 - 107 , LED&#39;s  111 ,  112 ,  113 ,  114 ,  115 ,  116 , and  117  are respectively disposed. 
   For representative purposes, the first LED  111  will be detailed. The first LED  111  may be a bullet shaped LED. A pair of lead wires  121  and  122  penetrates the first reflecting board member  101  from the side of the reflecting layer  101   a  to the opposite side. The reflecting layer  101   a  is not formed on the area where the lead wires  121  and  122  of the LED penetrate the reflecting board member  101 , so that the short circuit between the lead wires  121  and  122  is prevented. On the surface of the first reflecting board member  101  that is opposite to the reflecting layer  101   a , the lead wires  121  and  122  of LED  111  are electrically connected to a flexible printed circuit  26 , by a solder process for example, and the flexible printed circuit  26  is electrically connected to the LED drive circuit  24 . The same is true with the second to seventh LED&#39;s  112 - 117 , which are mounted on the second to seventh reflecting board members  102 - 107 , respectively. 
   A fabrication method for the light source unit  30  will be described in the following. In the first process, a board member having a shape shown in  FIG. 2  is cut from a synthetic resin board, and grooves, to facilitate bending the board, are formed on the side from which light is emitted, at the positions indicated with the broken lines in FIG.  2 . In the second process, the cutout synthetic resin board is subjected to a plating process except in the areas where the LED lead wires penetrate the board, so that the reflecting layers  101   a  to  107   a  are formed. In the third process, the first to seventh LED&#39;s  111 - 117  are mounted onto the reflecting layer surface of the synthetic resin board. The synthetic resin board is bent at the grooves cut into the board, and adjacent sides of each trapezoid are put together in the forth process, so that a concave open polyhedron shape is formed. In the fifth process, the lead wires of the LED&#39;s  111 - 117  and the flexible print circuit  26  are soldered together. Thereby, the LED&#39;s  111 - 117  are fixed to the corresponding reflecting board members  101 - 107 , respectively, by means of soldering processes. 
   As described above, since the light source unit  30  of the present embodiment is formed from a substrate plate, the fabrication process is simplified. Particularly, the processes for mounting the LED&#39;s are made efficient. Further, the time for each process is reduced thus the cost is reduced. 
   The number of LED&#39;s and reflecting board members is not restricted to the present embodiment. For example, as shown in the plan view in  FIG. 4 , trapezoidal reflecting board members  202 - 209  may be arranged around an octagonal reflecting board member  201 , and the LED&#39;s  211 - 219  may be mounted on reflecting board members  201 - 209 , respectively. Note that here, L 1 ′ and L 2 ′, respectively designate the side length of the reflecting board member  201  and the bottom side length of the reflecting board members  202 - 209 , and are determined so that the entire light from the LED&#39;s is concentrated on the incident end face of the light guide member  12  when the light source unit  30  is assembled and optically connected to the light guide member  12 . 
   Further, as shown in the pre-assembly structure or the development of  FIG. 5 , six reflecting board members  302 - 307  may be arranged around a hexagonal reflecting board member  301 , and six trapezoidal reflecting board members  308 - 313  may be arranged radially around the outer side of each reflecting board member  302 - 307 . Further, the LED&#39;s  321 - 333  may be mounted on the reflecting board members  301 - 313 , respectively. Note that here, L 1 ″, L 2 ″, and L 3 , respectively designate the side length of the reflecting board member  301 , the bottom side length of the reflecting board members  302 - 307 , and the bottom side length of the reflecting board members  308 - 313 , and are determined so that the entire light from the LED&#39;s is concentrated on the incident end face of the light guide member  12  when the light source unit  30  is assembled and optically connected to the light guide member  12 . 
   In the present embodiment, although only one LED is mounted on one reflecting board member, a plurality of LED&#39;s may be mounted on a single reflecting board member. Further, in the present embodiment, a bullet shaped LED is used, however, the shape or type of an LED is not restricted to the one used in this embodiment, so that any other type of LED, such as a laminated-type LED or a chip-type LED, or the like, may be used. Further, in the present embodiment, all the LED&#39;s radiate white light, however, the same number of red, green, and blue colored LED&#39;s, which corresponds to the three color principle, may be arranged on the reflecting board members, so that the composite white light can be supplied to the end face of the light guide member by radiating the three light colors from the LED&#39;s simultaneously. 
   Further, in the present embodiment, although the reflecting layer is formed by a plating process, an aluminum film of which the surface is subject to an electric non-conductance process may be applied to the reflecting board members, so as to form the reflecting layer, other than in the areas where lead wires of the LEDs penetrate the reflecting board member. 
   Furthermore, the fabrication process is not restricted to that in the present embodiment. As shown in  FIG. 6A , a concave open polyhedron  400  may be integrally formed as a composition of seven reflecting board members  101 - 107  made of synthetic resin. Then the seven LED&#39;s may be respectively mounted on the reflecting board members  101 - 107  after a reflecting layer is plated on the inner surface of the concaved open polyhedron  400 . Finally, a flexible printed circuit may be attached onto the outer surface of the concaved open polyhedron  400  for soldering each LED to the flexible printed circuit, as shown in FIG.  6 B. 
   Further, as shown in  FIG. 7A , the LED&#39;s  111 - 117  may be mounted on the reflecting board members  101 - 107  that are cutout from a synthetic resin board with one side having a reflecting layer. Then the reflecting board members  101 - 107  with the LED&#39;s  111 - 117  may be assembled into a concaved open polyhedron by putting each reflecting board member  101 - 107  together. Finally, a flexible printed circuit may be attached onto the outer surface of the concaved open polyhedron and each LED can be soldered to the flexible printed circuit, as shown in FIG.  7 B. 
   Although the embodiments of the present invention have been described herein with reference to the accompanying drawings, obviously many modifications and changes may be made by those skilled in this art without departing from the scope of the invention. 
   The present disclosure relates to subject matter contained in Japanese Patent Application No. 2002-042824 (filed on Feb. 20, 2002) which is expressly incorporated herein, by reference, in its entirety.