Abstract:
A light source device for a medical endoscope system comprises a lamp unit including a xenon lamp and a heat sink, with fins, certain ones of which form electrodes, a lamp housing into which the lamp unit is removably which is provided with first power electrodes and discharge electrodes of a static discharge circuit. These first power electrodes and discharge electrodes are biased in a direction of removal of the lamp unit. The first power electrodes are brought into contact with the heat sink electrodes and thrust back by the heat sink when the lamp unit is set in the lamp housing. The discharge electrodes are thrust back away from the discharge circuit by the heat sink on the way of insertion of the lamp unit into the lamp housing and allowed to return to electric coupling to the discharge circuit ground on the way of removal of the lamp unit from the lamp housing. A pivot door may be used and includes pin for blocking door closure if the lamp unit is not properly inserted and also includes a switch interlock for effecting power to the lamp unit. Rotational inserting/ejecting levers may also be used.

Description:
BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   The present invention relates to a light source device for providing illumination light to an endoscope system, in particular, a medical endoscope system. 
   2. Description of Related Art 
   A light source device for use with a medical endoscope system is detachably connected to an endoscope to supply illumination light to a body cavity through a light guide. The light source device generally has a lamp unit including an electric lamp, a lamp housing in which the lamp unit is removably installed, and an outer case in which the lamp housing is fixedly encased. The outer case is provided with an access door for opening and closing an access opening of the outer case to the lamp unit for periodic and temporary replacement of lamps. Periodic replacement of lamps is made at regular time intervals for the purpose of keep the light source device supplying a stable amount of illumination light. 
   One of light source devices for medical endoscope systems disclosed in, for example, Japanese Unexamined Patent Publication No. 6-67097 has a case provided with double access doors, namely an outer and an inner access door, for opening and closing an access opening of the case for an access to an electric lamp located far back from the access doors. The electric lamp is mounted to a heat sink fixedly installed in the case by means of fixing knobs. The inner access door serves as an interlock door to brake or open a lighting circuit for the electric lamp when it is opened or removed from the case. 
   Another light source device for medical endoscope systems disclosed in, for example, Japanese Unexamined Patent Publication No. 9-327435, has a case provided with an access door for opening and closing an access opening of the case for an access to an electric lamp mounted to a heat sink. The access door serves as a switch to bring a discharge circuit for discharging static electricity of the heat sink alive when it is opened or removed. The light source device ensures safety lamp replacement works because static electricity of the heat sink are discharged whenever the access door is opened or removed. 
   The light source device provided with double access doors has the problem that replacement of lamps involves opening and closing the double access doors and handling the fixing knobs to detach and fix the heat sink which are quite troublesome. 
   Further, in the prior art light source devices described above have the problem that the operator incurs a danger upon replacing lamps immediately after the service of the light source device because the heat sink is too hot to be set aside from the case. 
   SUMMARY OF THE INVENTION 
   It is therefore an object of the present invention to provide a light source device for a medical endoscope system that enables easy and safe lamp replacement works. 
   According to an aspect of the present invention, the foregoing object is accomplished by a light source device for supplying illumination light to an endoscope system that has a light source unit housing and a light source unit including an electric lamp, the electric lamp being electrically connected to a power source when the light source unit is inserted into the light source unit housing and disconnected from the power source when the light source unit is removed from the light source unit housing. The light source device comprises first power electrodes for transmitting electric power to the light source unit that are held for sliding movement in opposite directions for insertion and removal of the light source unit by the light source unit housing, second power electrodes for supplying electric power to the electric lamp which are fixedly attached to the light source unit, and biasing means incorporated in the light source unit housing for biasing the first power electrodes in the direction for removal of the light source unit. In the light source device, when the light source unit is inserted into the light source unit housing, the second power electrodes come to contact with and thrust back the first power electrodes against the biasing means, thereby electrically connecting the electric lamp to the power source. 
   The light source device thus structured keeps the second power electrodes of the light source unit reliably contacting with the first power electrodes of the light source unit housing under repulsion of the biasing springs when the light source unit is inserted in the light source unit housing in the right place. On the other hand, the light source unit is removed from the light source unit housing in a breeze with the assistance of the biasing springs. 
   According to another aspect of the present invention, the foregoing object is accomplished by a light source device for supplying illumination light to an endoscope system that has a light source unit housing and a light source unit including an electric lamp removably inserted into the light source unit housing. The light source device comprises a discharge circuit incorporated in the light source unit housing that operates to discharge static electricity of a charge built-up portion of the light source unit when electrically connected to the light source unit, sliding electrodes forming part of the discharge circuit and held for slide movement in opposite directions for insertion and removal of the light source unit by the light source unit housing, and biasing means for biasing the sliding electrodes in the direction for removal of the light source unit so as thereby to keep the sliding electrodes being electrically connected to the discharge circuit. In the light source device, the light source unit forces the sliding electrodes against the biasing means through engagement between the light source unit and the sliding electrodes so as to electrically disconnect the sliding electrodes from the discharge circuit following movement of the light source unit in the direction for insertion into the light source unit housing. Further, the light source unit allows the sliding electrodes to slide following movement of the light source unit in the direction for removal from the light source unit housing keeping in contact with the light source unit and then to be brought into electric connection with the discharge circuit, thereby discharging static electricity of the light source unit. 
   The light source device thus structured reliably brings the sliding electrodes into connection with the discharge circuit under repulsion of the biasing springs in the course of removing the light source unit from the light source unit housing, thereby discharging static electricity build up in the light source unit with the consequence that the light source unit is safely removed from the light source unit housing. Furthermore, the light source unit is removed from the light source unit housing in a breeze with the assistance of the biasing springs. 
   According to still another aspect of the present invention, the foregoing object is accomplished by a light source device for supplying illumination light to an endoscope system that has a light source unit housing and a light source unit including an electric lamp removably inserted into the light source unit housing. The light source unit comprises grip means for being gripped to hold the light source unit, a heat sink for holding the electric lamp, and insulating means of a material that is electrically nonconductive and low in thermal conductivity disposed between the grip means and the heat sink for thermally and electrically insulating the grip means from the heat sink. 
   The insulating means prevents the grip means from being influenced by heat of the heat sink. Therefore, the light source unit can be safely removed from the light source unit housing even when the heat sink is too hot to be handled immediately after the service of the light source device. Furthermore, the operator is prevented from incurring an electric shock upon gripping the grip means even when the heat sink is charged substantially. 
   According to a further aspect of the present invention, the foregoing object is accomplished by a light source device for supplying illumination light to an endoscope system that has a light source unit housing and a light source unit including an electric lamp removably inserted into the light source unit housing. The light source device has an access door for opening and closing an access opening of an outer case for an access to the light source unit and a projection provided on an inner side of the access door. The projection such as a pin strikes on the light source unit so as to prevent the access door from closing when the light source unit is incompletely inserted in the light source unit housing. 
   The light source device obviates an occurrence of wrong insertion of the light source unit into the light source unit housing. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects and features of the present invention will be clearly understood from the following detailed description when read with reference to the accompanying drawings, wherein the same numeral numbers have been used to denote same or similar parts or mechanisms throughout the drawings and in which: 
       FIG. 1  is a perspective outline view of a light source device according to an embodiment of the present invention; 
       FIG. 2  is a plane view of the light source device partly cutaway; 
       FIG. 3  is a perspective view of an internal structure of the light source device in which a light source unit is removed from a light source unit housing; 
       FIG. 4  is a perspective view of an internal structure of the light source device in which the light source unit housing is partly broken away; 
       FIG. 5A  is a schematic side view of the light source unit housing which is shown partly in cross section and the light source unit before insertion into the light source unit housing; 
       FIG. 5B  is a cross sectional view of a first power electrode. 
       FIG. 6  is a plan view of the light source unit housing and the light source unit before insertion into or after removal from the light source unit housing; 
       FIGS. 7A and 7B  are a plane and a side view of the light source unit at the beginning of insertion into the light source unit housing, respectively; 
       FIGS. 8A and 8B  are a plane and a side view of the light source unit inserted to a halfway position in the light source unit housing where a sliding electrode is disconnected from a discharge circuit, respectively; 
       FIGS. 9A and 9B  are a plane and a side view of the light source unit inserted closely to an end position in the light source unit housing, respectively; 
       FIGS. 10A and 10B  are a plane and a side view of the light source unit fully inserted in the light source unit housing, respectively; and 
       FIGS. 11A and 11B  are a plane and a side view of the light source unit in which ejectors of the light source unit are locked, respectively; 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   In the following description, parts which are not of direct importance to the invention and parts which are purely of conventional construction will not be described in detail. For example, details of the power supply circuit, the lighting circuit, the light guide means, the connector, etc. which are necessary to the light source unit, will not be set out in detail since their construction and operation can be easily arrived at by those skilled in the art. 
   Referring to the drawings in detail, and, in particular, to  FIGS. 1 and 2  showing a light source device  10  for endoscopes according to an embodiment of the present invention, the light source device  10  has a generally rectangular box-shaped case  12  provided with a door  14  for opening and closing an access opening  12 A. The door  14  is provided with a lock screw  16  that is tightened in a screw hole  18  of the case  12  to lock the door  14 . The door  14  is further provided with interlock release means such as a pin  20  close to the lock screw  16  and a pair of safety means such as pins  24  at the center. The interlock release pin  20  is lead into a bore  22  formed in the case  12  to provide electrical interlock between a xenon lamp  38  incorporated in a light source unit  30  (see  FIG. 3 ) and a power source (not shown) when the door  14  is closed and gets away from the bore  22  to disconnect the xenon lamp  38  from the power source when the door  14  is opened. The safety pins  24  are brought into a strike on parts of the light source unit  30  in a false position when the door  14  is closed. 
   As shown in  FIG. 2 , there are installed in the case  12  a stationary light source unit housing  26  in which the light source unit  30  is detachably mounted, a lighting control unit  28  including a constant current circuit and an on/off switch, and a cooling fan  34 . These light source unit housing  26  and lighting unit  28 , more specifically, the lamp and the constant current circuit, are electrically connected through cables  32 . The cooling fan  26  is disposed adjacent to the light source unit housing to cool the interior of the light source unit housing  26 . The light source unit housing  26  faces the access opening  12 A of the case  12 . The light source unit  30  shown in  FIGS. 3 through 6  is inserted into and removable from the light source unit housing  26  through the access opening  12 A. 
   Referring to  FIGS. 3 through 6 , the light source unit  30  is principally composed of a xenon lamp  38  as a light source, heat sinks  42  and  44 , each serving as a socket having a socket bore  42   a  for the xenon lamp  38 , a lamp mount board  40 , an ejector bracket  50  available as a grip, a pair of ejectors  52  pivotally mounted on opposite extreme ends of the ejector bracket  50 , and a pair of ejector locks  56  pivotally mounted cooperatively with the ejectors  52 , respectively, on the ejector bracket  50 . As shown in  FIG. 4 , the xenon lamp  38  is detachably held in the socket bores  42   a  of the heat sinks  42  and  44 . The heat sinks  42  and  44 , that are made of a good thermally and electrically conductive material such as aluminum or the like and electrically isolated, or otherwise separated by a distance, from each other, are provided with a number of radial fins  42   b  and  44   b , respectively, so as to allow more efficient heat radiation. As will be described later, one of the fins of each of the heat sink is adapted to function as a second power electrode for the xenon lamp  38 . The xenon lamp  38  is electrically connected to the heat sinks  42  and  44 , namely the lamp socket, when held in position in the socket bores  42  of the heat sinks  42  and  44 . As will be described later, the heat sinks  42  and  43 , especially their associated electrode fins, are brought into contact with positive and negative first power electrodes  46  and  48  connected to a power supply circuit (not shown) through which electric power is supplied to the light source unit  30  and installed in the light source unit housing  26 , respectively, when the light source unit  30  is set in position within the light source unit housing  26 . 
   The lamp mount board  40  to which the heat sinks  42  and  44  are fixedly mounted is made of a low thermally conductive and electrically nonconductive material such as an epoxy resin and is shaped in form of a board. When the light source unit  30  is put in position within the light source unit housing  26 , the lamp mount board  40  is located between cylindrical pillars  36  fixedly located within the light source unit housing  26  to serve as one of walls or a lid of the light source unit housing  26  so as to prevent an operator from accessing to the heat sinks  42  and  44  and/or the xenon lamp  38  within the light source unit housing  26 . The ejector bracket  50  is fixedly attached to the lamp mount board  40  at the side remote from the heat sinks  42  and  44  and extends horizontally. The ejector bracket  50  at opposite extreme ends is provided with the ejectors  52  and  54 , respectively. As clearly shown in  FIG. 6 , the ejector  52  is pivotally mounted on a pivot pin  54  vertically extending from the ejector bracket  50 . The ejector  52  has a semi-circular catch recess  52 A that is similar in shape to the cylindrical pillar  36  and capable of catching the cylindrical pillar  36  and a locking projection  52 B. The ejector lock  56  is disposed adjacent to each of the ejectors  52  and pivotally mounted on a pivot pin  58  vertically extending from the ejector bracket  50 . The ejector lock  56  has a locking recess  56 B capable of engaging with the locking projection  52 B of the ejector  52 . When the ejector  52  is pivotally turned passing over the injector lock  56  in one direction and then returned halfway in the counter direction, the ejector  52  brings the locking projection  52 B into engagement with the locking recess  56 B of the ejector lock  56  to be locked in the turned position. 
   As shown in detail in  FIGS. 4 ,  5 A and  5 B, the light source unit housing  26  is provided with the first power electrodes  46  and  48 , a pair of sliding discharge electrodes  60  and  62  and a discharge circuit terminal  78 . The first power electrode  48  is held by an electrode holder  66  for slide movement in directions of insertion and removal of the light source unit  30  with respect to the light source unit housing  26  (which are hereafter referred to as an insertion direction and a removal direction, respectively) and biased by bias means such as a biasing spring  67  in the removal direction so as to protrude from the electrode holder  66 . Similarly, the first power electrode  46  is held by an electrode holder  64  for slide movement in both insertion and removal directions and biased in the removal direction by a biasing spring (not shown) so as to protrude from the electrode holder  64 . When the light source unit  30  is inset in position within the light source unit housing  26 , specific fins, that are adapted to function as a second power electrodes  42   c  and  44   c , of the heat sinks  42  and  44  are brought into contact with contact surfaces  46 A and  48 A of the first power electrodes  46  and  48 , respectively, held by the electrode holders  64  and  66 , respectively, and push the electrodes  46  and  48  against the biasing springs  67 , respectively. Even when the light source unit  30  is fully inserted into the light source unit housing  26 , there is left a predetermined clearance between the electrodes  42   c  and  44   c  of the heat sinks  42  and  44  and the electrode holders  64  and  66 , respectively. 
   As shown in detail in  FIG. 5A , the sliding discharge electrode  60  has an upright tongue  60 A and is supported for slide movement in both insertion and removal directions within a follow base  26 A of the light source unit housing  26 . Bias means such as a biasing spring  70  is mounted between the sliding discharge electrode  60  and the electrode holder  64  within the base  26 A so as to bias the sliding discharge electrode  60  in the removal direction of the light source unit  30 . The upright tongue  60 A of the sliding discharge electrode  60  projects out of the base  26 A through an opening  74  of the base  26 A (see  FIG. 3 ). Similarly, the sliding discharge electrode  62  has an upright tongue  62 A and is supported for slide movement in both insertion and removal direction of the light source unit  30  within a follow base  26 A of the light source unit housing  26 . A biasing spring  72  is mounted between the sliding discharge electrode  62  and the electrode holder  66  within the base  12 A so as to bias the sliding discharge electrode  62  in the removal direction of the light source unit  30 . The upright tongue  62 A of the sliding discharge electrode  62  projects out of the base  26 A through an opening  76  of the base  26 A (see  FIG. 3 ). The sliding discharge electrodes  60  and  62  are forced against the biasing springs  70  and  71 , respectively, by the radial fins  42   b  and  44   b  of the heat sink  42  and  44 , respectively, when the light source unit  30  is inserted into the light source unit housing  26 . 
   The discharge circuit terminal  78 , that is generally U-shaped, is fixedly mounted within the base  26 A of the light source unit light source unit housing  26  and grounded through a discharge circuit  80 . The discharge circuit terminal  78  is so located that the sliding discharge electrodes  60 A and  62 A make slide contact with the discharge circuit terminal  78 . More specifically, when the light source unit  30  is removed from the light source unit housing  26 , the sliding discharge electrodes  60  and  62  are forced in the removal direction of the light source unit  30  by the biasing spring  70  and  72 , respectively, to be brought into slide contact with the discharge circuit terminal  78 . On the other hand, when the light source unit  30  is inserted into the light source unit housing  26 , the sliding discharge electrodes  60  and  62  are forced in the insertion direction through the radial fins  42   b  and  44   b , respectively, against the biasing spring  70  and  72 , respectively, so as thereby to be separated from the discharge circuit terminal  78 . The base  26 A is provided with a guide plate  68  as shown in  FIG. 3 . The guide plate  68  has a width quite slightly smaller than the distance by which the heat sinks  42  and  44  are separated and guides movement of the light source unit  30 , in particular the heat sinks  42  and  44 , in both insertion and removal directions when the light source unit  30  is moved in the insertion and removal directions. 
   The following description will be directed to operation of the light source device  10  with reference to  FIGS. 7 through 11 . When the light source unit  30  is inserted into the light source unit housing  26 , the door  14  is opened (see  FIG. 1 ), and then the light source unit  30  is inserted through the access opening  12 A and positioned between the pillars  36 . As shown in  FIGS. 7(A) and 7(B) , at the beginning of insertion of the light source unit  30  into the light source unit housing  26 , the radial fins  42   b  and  44   b  of the heat sink  42  and  44  are brought into contact with the upright tongues  60 A and  62 A of the sliding discharge electrodes  60  and  62 , respectively. With further movement of the light source unit  30  in the insertion direction, the radial fins  42   b  and  44   b  of the heat sink  42  and  44  forces the upright tongues  60 A and  62 A to slide the sliding discharge electrodes  60  and  62 , respectively, on the discharge circuit terminal  78  in the insertion direction and then to separate them from the discharge circuit terminal  78 . The further continuous movement of the light source unit  30  for insertion of the light source unit  30  into the light source unit housing  26  brings the catch recesses  52 A of the ejectors  52  to catch the pillars  36 , respectively, as shown in  FIGS. 8(A) and 8(B) , and subsequently pivotally turns the ejectors  52  inwardly in opposite directions about the pivot pins  54 , respectively, with their points of action at the pillars  36 , respectively, as shown in  FIG. 9(A) . 
   When the light source unit  30  is fully inserted into the light source unit housing  26 , the electrodes  42   c  and  44   c  of the heat sink  42  and  44  come to contact with the counter electrodes  46  and  48 , respectively, as shown in  FIGS. 10(A) and 10(B) . When the light source unit  30  is forcibly pushed in the insertion direction after the electrodes  42   c  and  44   c  of the heat sink  42  and  44  has been brought into contact with the counter electrodes  46  and  48 , respectively, the electrodes  42   c  and  44   c  of the heat sink  42  and  44  forces the counter electrodes  46  and  48  against the biasing springs  67 . At this time, the light source unit  30  further turns the ejectors  52  to thrust aside the associated ejector locks  52  outwardly in opposite directions and then allows them to turn back outwardly in opposite directions so as thereby to bring the locking projections  52 B of the ejectors  52  into engagement with the locking recesses  56 B of the ejector locks  56 , respectively, as shown in  FIGS. 11(A) and 11(B) . As a result, each of the ejectors  52  is locked by the ejector lock  56 . In this way, insertion of the light source unit  30  into the light source unit housing  26  is completed with the consequence that the electrodes  42   c  and  44   c  of the heat sink  42  and  44  are kept in close contact with the electrodes  64  and  66 , respectively, under proper-contact pressure. Thereafter, when the door  14  is closed, the interlock release pin  20  is lead into the bore  22  of the case  12  to remove interlock between the xenon lamp  38  and the lighting unit  28  so as thereby to allow the xenon lamp  38  to be supplied electric power. 
   In the case where the light source unit  30  is incompletely inserted in the light source unit housing  26 , or otherwise where the ejectors  52  are successively locked by the ejector locks  56 , when the door  14  is turned toward the access opening  12 A, then, the safety pins  24  strike on, for example, the ejectors  52 , the ejector locks  56  or the ejector bracket  50 , to hinder the door  14  from completely closing. Accordingly, the interlock release pin  20  is left out of the bore  22 , thereby keeping electrical interlock between the xenon lamp  38  and the power source released. Therefore, the xenon lamp  38  is prevented from being excited while the door  14  is incompletely closed. 
   On the other hand, for removal of the light source unit  30  from the light source unit housing  26  for the purpose of, for example, replacement of lamps, the door  14  is opened. At this time, while the safety pins  24  are moved away from the ejectors  52  or the ejector locks  56 , the interlock release pin  20  is pulled out of the bore  22  to release the electrical interlock between the xenon lamp  38  and the power source. Therefore, an access to the light source unit  30  or the xenon lamp  38  is safely allowed. After the door  14  is fully opened, the ejectors  56  are turned inwardly in opposite directions, respectively, to unlock the ejectors  52 , respectively, as shown in  FIG. 10(A) . When the ejectors  52  are turned outwardly in opposite directions, respectively, about the pivot pins  54  with their points of reaction at the pillars  36 , the light source unit  30  is pulled in the removal direction, thereby separating the electrodes  42   c  and  44   c  of the heat sink  42  and  44  away from the electrodes  46  and  48  of the light source unit housing  26 , respectively as shown in  FIGS. 9(A) and 9(B) . At this time, the light source unit  30  is forced in the removal direction by the biasing springs  70  and  72  through the sliding discharge electrodes  60  and  62 , turning the ejectors  52  is made quite easy. After completely erecting the ejectors  52  as shown in  FIGS. 8(A) and 8(B) , the ejector bracket  50  is grasped and pulled in the removal direction to pull the light source unit  30  fully out of the light source unit housing  26 . 
   Since the ejector bracket  50  is attached to the heat sinks  42  and  44  through the lamp mount board  40  that is low in thermal conductivity, the ejector bracket  50  and the ejectors  52  are at a comparatively low temperature even in the case where the heat sinks  42  and  44  are still too hot to be caught by hand. Therefore, the operator can grasp the ejector bracket  50  safely and pull out the light source unit  30 . 
   During further movement of the light source unit  30  in the removal direction, the sliding discharge electrodes  60  and  62  are brought into slide contact with the discharge circuit terminal  78  to discharge electric charges of the heat sinks  42  and  44  through the discharge circuit  80 , thereby lowering electric potentials of the heat sinks  42  and  44  almost equally to that of the light source unit housing  26 . The lamp mount board  40 , that is electrically nonconductive, is positioned between the cylindrical pillars  36 , preventing the operator from touching the heat sinks  42  and  44  before the heat sinks  42  and  44  have been discharged. In other words, when the light source unit is pulled out to a position where the heat sinks  42  and  44  can be touched by the operator, discharge of the heat sinks  42  and  44  have credibly been completed. 
   The present invention has been described with reference to preferred embodiments thereof. However, it will be appreciated that variants and other embodiments can be effected by person of ordinary skill in the art without departing from the scope of the invention. 
   The present invention has been described with reference to preferred embodiments thereof. However, it will be appreciated that variants and other embodiments can be effected by person of ordinary skill in the art without departing from the scope of the invention.