Abstract:
A light source apparatus includes: a lamp replacement door configured to open and close a lamp replacement window; an igniter replacement door configured to open and close an igniter replacement window which is opened at a position different from the position of the lamp replacement window; a door opening detection switch configured to detect the opening and closing of the lamp replacement door; a circuit breaker device configured, when the opening state of the lamp replacement door is detected by the door opening detection switch, to interrupt power supply to an electric circuit; and a door opening regulation mechanism configured to lock the closing state of the igniter replacement door, and configured to permit the opening of the igniter replacement door.

Description:
[0001]    This application claims benefit of Japanese Application No. 2008-043196 filed in Japan on Feb. 25, 2008, the contents of which are incorporated by this reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a light source apparatus configured to prevent a second door from being opened when a first door is closed. 
         [0004]    2. Description of the Related Art 
         [0005]    Conventionally, a discharge lamp, such as a xenon lamp, which generates high luminance light, is provided as a light source of a light source apparatus for supplying illumination light to an endoscope, a projector, and the like. Further, between the discharge lamp and a lamp power source, there is provided an igniter for temporarily boosting the electric power supplied from the lamp power source to a high voltage. When the boosted high voltage is applied to the discharge lamp, a discharge is started in the discharge lamp, so that the discharge lamp is turned on. 
         [0006]    In the case where consumables, such as the discharge lamp used in the light source apparatus are intended to be replaced, as disclosed in, for example, Japanese Patent Application Laid-Open Publication No. 6-175043, after a lamp replacement door (first door) of the light source apparatus is opened, the discharge lamp is taken out together with a heat sink which holds the discharge lamp, so as to be replaced with a new discharge lamp, and thereafter the new discharge lamp is again housed in the light source apparatus. In this case, when the lamp replacement door is opened, a circuit breaker device is operated, so as to interrupt the power source circuit. 
         [0007]    On the other hand, the igniter is also a consumable, but the igniter is provided in the inside of the light source apparatus because the igniter has a longer life and a lower frequency of replacement as compared with the discharge lamp. Therefore, when the igniter is replaced, a top cover is first removed, and then the igniter is taken out after a shield case covering the igniter is removed. 
       SUMMARY OF THE INVENTION 
       [0008]    A light source apparatus according to the present invention includes: 
         [0009]    an apparatus main body; 
         [0010]    a first opening portion provided in the apparatus main body, and a first door configured to open and close the first opening portion; 
         [0011]    a second opening portion provided in the apparatus main body at a position different from the position of the first opening portion, and a second door configured to open and close the second opening portion; 
         [0012]    an opening and closing detecting portion configured to detect the opening and closing of the first door; 
         [0013]    a circuit breaker device configured, when the opening state of the first door is detected by the opening and closing detecting portion, to interrupt power supply to a circuit in the apparatus main body; and 
         [0014]    a door opening regulation mechanism configured, when the closing state of the first door is detected by the opening and closing detecting portion, to lock the closing state of the second door, and configured, when the opening state of the first door is detected by the opening and closing detecting portion, to permit the opening of the second door. 
         [0015]    According to such configuration, when the first door is not opened, the door opening regulation mechanism prevents the lock of the second door from being released. Thus, when the second door is opened, the power source circuit can be interrupted by the circuit breaker switch on the side of the first door without provision of circuit breaker switches on both sides of the first door and the second door. As a result, it is possible to realize the reduction in the number of components by sharing the components, and possible to realize the simplification of the electrical wiring and assembling. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  to  FIG. 14  show a first embodiment according to the present invention, in which: 
           [0017]      FIG. 1  is an overall perspective view of a light source apparatus; 
           [0018]      FIG. 2  is a perspective view in the state where a top cover of the light source apparatus is removed; 
           [0019]      FIG. 3  is a perspective view of a chassis in which a lamp case is provided; 
           [0020]      FIG. 4  is a perspective view of the chassis viewed from the bottom surface; 
           [0021]      FIG. 5  is a sectional view taken along the line V-V in  FIG. 1 ; 
           [0022]      FIG. 6  is a sectional view in the state where a lamp replacement door is removed in the state shown in  FIG. 5 ; 
           [0023]      FIG. 7  is a sectional view taken along the line VII-VII in  FIG. 6 ; 
           [0024]      FIG. 8  is a bottom view of a lamp base in which an igniter substrate is omitted, in the state where the lamp replacement door is closed; 
           [0025]      FIG. 9  is a bottom view of the lamp base in which the igniter substrate is omitted, in the state where the lamp replacement door is opened; 
           [0026]      FIG. 10  is a perspective view corresponding to  FIG. 3 , in the state where the lamp case is removed; 
           [0027]      FIG. 11  is a perspective view corresponding to  FIG. 10 , in the state where the lamp base is removed and at the time when the lamp replacement door is closed; 
           [0028]      FIG. 12  is a perspective view corresponding to  FIG. 10 , in the state where the lamp base is removed and at the time when the lamp replacement door is opened; 
           [0029]      FIG. 13A  shows a slider and is a sectional view taken along the line a-a in  FIG. 13D ; 
           [0030]      FIG. 13B  is a sectional view taken along the line b-b in  FIG. 13A ; 
           [0031]      FIG. 13C  is a sectional view taken along the line c-c in  FIG. 13A ; 
           [0032]      FIG. 13D  is a front view of the slider; 
           [0033]      FIG. 13E  is a rear view of the slider; 
           [0034]      FIG. 13F  is a front view of a guide hole portion in which a discharge lamp is inserted; and 
           [0035]      FIG. 14  is a sectional view taken along the line XIV-XIV in  FIG. 8 . 
           [0036]      FIG. 15  to  FIG. 20  show a second embodiment according to the present invention, in which: 
           [0037]      FIG. 15  is a sectional view corresponding to  FIG. 5 ; 
           [0038]      FIG. 16  is a sectional view corresponding to  FIG. 6 ; 
           [0039]      FIG. 17  is a sectional view taken along the line XVII-XVII in  FIG. 15 ; 
           [0040]      FIG. 18  is a sectional view taken along the line XVIII-XVIII in  FIG. 16 ; 
           [0041]      FIG. 19  is a sectional view corresponding to  FIG. 16 , in the state where both of a lamp replacement door and an igniter replacement door are opened; and 
           [0042]      FIG. 20  is a sectional view taken along the line XX-XX in  FIG. 19 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0043]    In the following, embodiments according to the present invention will be described with reference to the accompanying drawings. 
       First Embodiment 
       [0044]      FIG. 1  to  FIG. 14  show a first embodiment according to the present invention. Note that in the following, the right and left directions will be explained by taking the front view as a reference. 
         [0045]    Reference numeral  1  in  FIG. 1  and  FIG. 2  denotes a light source apparatus which supplies illumination light to, for example, an endoscope. An apparatus main body  2  of the light source apparatus  1  has a main body portion  3  and a top cover  4 . The main body portion  3  is formed approximately in a U-shape, in which a front panel  3   b  is fixed to a front portion of a chassis  3   a , in which a rear plate  3   c  is fixed to a rear portion of the chassis  3   a , and in which the upper surface and both side surfaces are opened. On the other hand, the top cover  4  is formed approximately in a U-shape so as to cover the upper surface, and the left and right side surfaces of the main body portion  3 . 
         [0046]    Further, in the rear left and right portions of the chassis  3   a , there are provided a lamp case  5  configured to house a lamp unit, and a power source case  6  configured to house a power source unit which supplies power to each of drive portions. Further, a control board  7  configured to perform overall control of the light source apparatus  1  is fixed to the upper surface of the power source case  6 . Further, an optical system  9  is provided in front of the lamp case  5 , and an air supply pump  8  is provided in front of the power source case  6 . 
         [0047]    Further, an operation portion  11  and a socket portion  12  are provided in the front panel  3   b . In the operation portion  11 , there are provided at predetermined positions various switches such as a power source switch, a switch for adjusting the light quantity of illumination light emitted from a discharge lamp housed in the lamp case  5 , a switch for adjusting a diaphragm arranged in the optical system  9 , and a pump switch for switching the operation and stop of the air supply pump  8 . Further, there is attached to the socket portion  12 , a light guide connector (not shown) fixed to an end portion of a universal cord extended from an endoscope which is not shown. 
         [0048]    When the light guide connector is attached to the socket portion  12 , the illumination light from the discharge lamp housed in the lamp case  5  can be made incident, via the optical system  9 , on the incident end surface of a light guide fiber projecting from the light guide connector. Further, an air supply tube projecting from the light guide connector is connected to an air supply conduit (not shown) extended from the air supply pump  8 , so that the air can be supplied. 
         [0049]    As shown in  FIG. 3 , the lamp case  5  has a shielding function, and an opening window  5   a  is formed in the left side surface of the lamp case  5 . Further, as shown in  FIG. 5  to  FIG. 7 , a lamp replacement window  4   a  as a first opening portion, which enables the lamp unit to be accessed from the outside via the opening window  5   a , is formed in the surface of the top cover  4 , which faces the opening window  5   a , that is, in the left side surface of the top cover  4 . The lamp replacement window  4   a  is closed by a lamp replacement door  14  as a first door. 
         [0050]    A protection member  15  and a switch pressing member  16  are fixed to the inner surface of the lamp replacement door  14 . Both of the members  15  and  16  are formed of an insulating material, such as a resin. In the present embodiment, the switch pressing member  16  is fixed to one side (on the deep side in the figure) of the lamp replacement door  14 . The switch pressing member  16  is projected in the direction of the lamp replacement window  4   a  formed in the top cover  4 , and a taper guide surface  16   a  is formed at the distal end portion of the switch pressing member  16 . 
         [0051]    When the lamp replacement door  14  is attached to the lamp replacement window  4   a  formed in the top cover  4 , and when the lamp replacement door  14  is screwed to the top cover  4  via a thumb screw  17 , the switch pressing member  16  is made to penetrate the lamp replacement window  4   a  which is opened in the top cover  4 , so as to face the inside of the apparatus main body  2 . A lamp replacement door opening detection switch  21 , as an opening and closing detecting portion, is arranged at a position at which the switch pressing member  16  is made to face the inside of the apparatus main body  2 , and which is between the lamp case  5  and the top cover  4 . The lamp replacement door opening detection switch  21  is a twin switch having an interlock switch and a discharge switch, and is fixed to the chassis  3   a  via a bracket  22 . 
         [0052]    When the lamp replacement door opening detection switch  21  detects the opening and closing of the lamp replacement door  14 , and when the lamp replacement door  14  is opened, the interlock switch is turned off. Thereby, the power source circuit of the power source unit housed in the power source case  6  is interrupted by a known circuit breaker device connected to the interlock switch, so that the power supply to the electric circuit in the apparatus main body  2  is interrupted. At the same time, the discharge switch is turned on to make a discharging circuit connected, so that the residual voltage in the electric circuit is released. Further, when the lamp replacement door  14  is closed, the interlock switch is turned on, so that the power source circuit is connected to make the discharge switch turned off. 
         [0053]    Further, a switch pressing portion  21   a  provided in the lamp replacement door opening detection switch  21  is arranged at a position at which the switch pressing portion  21   a  is brought into slide contact with the taper guide surface  16   a  formed on the switch pressing member  16  so as to be pressed by the taper guide surface  16   a . Further, the free end side of a leaf spring guide  23  is brought into contact with the switch pressing portion  21   a . The fixed end side of the leaf spring guide  23  is fixed by being substantially horizontally extended toward the left side surface of the chassis  3   a.    
         [0054]    When the switch pressing member  16  is made to penetrate the lamp replacement window  4   a  to face the inside of the apparatus main body  2 , the taper guide surface  16   a  formed at the distal end portion of the switch pressing member  16  presses the leaf spring guide  23 , so that the switch pressing portion  21   a  of the lamp replacement door opening detection switch  21  is pressed via the leaf spring guide  23 . Then, the lamp replacement door opening detection switch  21  is turned on, so that the power source case  6  is brought into the state of being able to supply electric power. On the other hand, when the switch pressing member  16  is extracted from the lamp replacement window  4   a , the pressing force against the switch pressing portion  21   a  is released. Thereby, the lamp replacement door opening detection switch  21  is turned off, so that the power supply from the power source case  6  is interrupted. Note that the above described leaf spring guide  23  has both a function of guiding the switch pressing member  16  to the switch pressing portion  21   a , and a function of amplifying the switching operation of the switch pressing portion  21   a.    
         [0055]    Further, a lamp base  26  is arranged in the lamp case  5 . The lamp base  26  is formed of a material, such as a ceramic material, having high heat transfer and insulating properties, and is fixed to the chassis  3   a  by using a screw, and the like. 
         [0056]    A known lamp unit (not shown) is fixed on the lamp base  26 . The lamp unit is configured so as to be freely taken out from the opening window  5   a  which is opened in the lamp case  5 . A negative side heat sink and a positive side heat sink are provided in the lamp unit, and the discharge lamp is detachably held between both the heat sinks. The heat sinks are connected to a negative electrode  35   a  and a positive electrode  35   b  (see  FIG. 10 ) which are vertically erected on the lamp base  26 . 
         [0057]    As shown in  FIG. 3 ,  FIG. 5 ,  FIG. 6  and  FIG. 10 , the lamp base  26  is formed in a box shape which has a predetermined height and the lower portion of which is opened. The opening end edge of the lamp base  26  is fixed to the chassis  3   a . The upper surface of the lamp base  26  is formed at a position higher than the lower edge portion of the opening window  5   a  formed in the lamp case  5 , and a guide hole portion  26   a  is formed in the side surface of the lamp base  26 , which is exposed from the opening window  5   a . A slider  27  is inserted into the guide hole portion  26   a  so as to be freely moved forward and backward. 
         [0058]    The slider  27  is formed of an insulating material, such as a resin. As shown in  FIG. 13A  to  FIG. 13E , the slider  27  has a rectangular flat upper surface  27   a , and a front surface portion  27   b  is formed at the front end of the upper surface  27   a . A side surface portion  27   c  is formed on one side of the upper surface  27   a , and a side surface block portion  27   d  is formed on the other side. A stopper portion  27   e  is notched and formed on the front surface portion  27   b  side of the side surface portion  27   c . Further, a claw portion  27   f  projecting backward is formed in the rear end portion of the side surface block portion  27   d . Further, a shaft portion  27   g  is extended backward from the front surface portion  27   b  along the rear surface of the upper surface  27   a , and a snap ring  28  is fitted to the extended end portion of the shaft portion  27   g . Further, a return spring  29  is inserted into the shaft portion  27   g.    
         [0059]    As shown in  FIG. 13F , the guide hole portion  26   a  formed in the lamp base  26  has a substantially U-shaped main body insertion hole portion  26   b  in which the upper surface  27   a , the side surface portion  27   c , and the side surface block portion  27   d  of the slider  27  are inserted, and has a shaft insertion hole portion  26   c  formed in a U-shaped groove which communicates with the main body insertion hole portion  26   b , and in which the shaft portion  27   g  is inserted. The shaft insertion hole portion  26   c  is formed to have a groove diameter which is larger than the diameter of the shaft portion  27   g , and which is smaller than the diameter of the snap ring  28 . 
         [0060]    In order to attach the slider  27  to the guide hole portion  26   a , the return spring  29  is first inserted into the shaft portion  27   g , and thereafter the upper surface  27   a , the side surface portion  27   c , and the side surface block portion  27   d  are inserted into the main body insertion hole portion  26   b . Further, the shaft portion  27   g  is inserted into the shaft insertion hole portion  26   c . Then, the snap ring  28  is fitted to the end portion of the shaft portion  27   g  which is made to penetrate the shaft insertion hole portion  26   c  to project to the inner surface of the lamp base  26 . Thereby, the assembling is completed. Note that slider guides  26   e  and  26   f  for guiding the width direction of the slider  27  are projectingly provided on a ceiling surface  26   d  in the lamp base  26 . 
         [0061]    When the slider  27  is attached at a predetermined position with respect to the guide hole portion  26   a  as shown in  FIG. 8 , the return spring  29  inserted in the shaft portion  27   g  is held between the inner surface of the front surface portion  27   b  of the slider  27  and the side surface of the lamp base  26 , so that the slider  27  is ejected from the side surface of the lamp base  26  by an elastic repulsive force of the return spring  29 . Note that the snap ring  28  is fitted to the end portion of the shaft portion  27   g , and hence the slider  27  is prevented from coming off from the guide hole portion  26   a . Further, when the slider  27  is pressed and moved into the lamp base  26 , the stopper portion  27   e  formed in the side surface portion  27   c  is hooked on the side surface of the lamp base  26 , so that the stroke end in the backward movement is regulated. Further, the slider guides  26   e  and  26   f  are provided so as to face both side surfaces of the slider  27 , and the upper surface  27   a  is set close to the ceiling surface  26   d  of the lamp base  26 , so that the slider  27  is smoothly moved forward and backward by being guided by the three surfaces. 
         [0062]    When the lamp replacement window  4   a  is closed by the lamp replacement door  14 , a pressing surface  15   a  formed on the protection member  15  fixed to the inner surface of the lamp replacement door  14  is brought into contact with the slider  27 , so as to press and retract the slider  27 . The stroke at this time is set shorter than the stroke end set beforehand. 
         [0063]    Further, an igniter  31  electrically connected to the power source case  6  is housed in the lamp base  26 . The igniter  31  is configured to turn on the discharge lamp by boosting a voltage generated in the power source case  6  to a high voltage and by applying the boosted high voltage to the discharge lamp. As shown in  FIG. 14 , a substrate (igniter substrate)  32  of the igniter  31  is hangingly provided in the lamp base  26  via a plurality of (three in the present embodiment) support bolts  33 . 
         [0064]    Further, feeder lines, respectively extended from the negative electrode  35   a  and the positive electrode  35   b  which are provided in the lamp base  26 , are connected to the corresponding support bolts  33 , respectively. Further, the power source line extended from the power source case  6  is connected to the corresponding other support bolt  33  via the known circuit breaker device connected to the interlock switch provided in the lamp replacement door opening detection switch  21 . 
         [0065]    In the following, there will be described fastening structures of the respective support bolts  33 . Note that the fastening structures of the respective support bolts  33  are almost the same, and hence only the fastening structure of one of the support bolts  33  will be described. 
         [0066]    A boss portion  37  is projectingly provided at a position corresponding to the mounting position of each of the support bolts  33  on the ceiling surface  26   d  in the lamp base  26 . A bolt hole portion  37   a , in which a bolt head  33   a  of the support bolt  33  is dropped into, is bored in the boss portion  37 . As shown in  FIG. 12 , the bolt head  33   a  is formed into an elliptic shape, and the inner circumference of the bolt hole portion  37   a  is formed into a rectangular shape so as to be able to house the bolt head  33   a  (see  FIG. 10 ). Therefore, when the bolt head  33   a  is dropped into the bolt hole portion  37   a , the bolt head  33   a  engages with the inner circumference of the bolt hole portion  37   a , so that the movement of the bolt head  33   a  in the rotation direction is regulated. 
         [0067]    Further, a screw portion insertion hole  37   b  is bored in the bottom portion of the bolt hole portion  37   a . A first nut  40  is screwed so as to be fastened and fixed, via a washer  39 , to a screw portion  33   b  which is made to penetrate the screw portion insertion hole  37   b . Further, the first and second terminals  42   a  and  42   b  are inserted in the screw portion  33   b  which is made to project downward from the first nut  40 , and second and third nuts  43   a  and  43   b  are screwed to the lower surface of the terminal. The second and third nuts  43   a  and  43   b  form a double nut. The first and second terminals  42   a  and  42   b  are pressed to be fixed between the first nut  40 , and the second and third nuts  43   a  and  43   b . Further, since the second and third nuts  43   a  and  43   b  form the double nut structure, the first to third nuts  40 ,  43   a  and  43   b  are prevented from being loosened, so that poor contact is prevented from being caused in the first and second terminals  42   a  and  42   b . Note that the support bolt  33  and the respective nuts  40 ,  43   a  and  43   b  are formed of a conductive material, such as iron, brass and aluminum. 
         [0068]    Further, a hole portion  45   a  of a contact bolt  45  is inserted into the screw portion  33   b  which is made to project from the lower end of the third nut  43   b . The contact bolt  45 , whose screw portion  45   b  is inserted into a through hole  32   a  bored in the igniter substrate  32 , is fastened by a contact nut  46  screwed into the screw portion  45   b  projected on the opposite side of the igniter substrate  32 . Note that the distal end surface of the screw portion  45   b  is slightly projected from the contact nut  46 . 
         [0069]    A land is formed around the through hole  32   a  bored in the igniter substrate  32 . The land is electrically connected to the first and second terminals  42   a  and  42   b  via the contact bolt  45 , the screw portion  33   b  of the support bolt  33 , and the respective nuts  43   a  and  43   b . Note that the contact bolt  45  is formed of a conductive material, such as iron, brass, and aluminum. A lock nut  48  is fastened, via a spring washer  47 , to the screw portion  33   b  of the support bolt  33  inserted in the hole portion  45   a  of the contact bolt  45 . As described above, the screw portion  45   b  of the contact bolt  45  is slightly projected from the contact nut  46 . Thus, even when the lock nut  48  is strongly fastened, the fastening load is prevented from being applied to the igniter substrate  32 , so that the igniter substrate  32  can be effectively protected. 
         [0070]    Further, the contact bolt  45  and the contact nut  46  are fastened to each other so as to sandwich the igniter substrate  32  therebetween. Thus, even when the screw portion  33   b  of the support bolt  33  is extracted from the hole portion  45   a  of the contact bolt  45 , the contact bolt  45  is prevented from dropping out of the igniter substrate  32 . Therefore, when the lock nut  48  is loosened, only the igniter substrate  32  is separated from the screw portion  33   b  of the support bolt  33 . Note that there is formed in the igniter substrate  32  an electric circuit which generates a high voltage pulse for turning on the discharge lamp. 
         [0071]    Further, an igniter replacement window  3   d  as a second opening portion, which allows access to the igniter  31  from the outside, is formed in a portion positioned within the inner circumference of the lamp base  26  of the chassis  3   a . The igniter replacement window  3   d  is closed by an igniter replacement door  51  as a second door. 
         [0072]    As shown in  FIG. 4 ,  FIG. 5  and  FIG. 6 , a latch piece  51   a , which is hooked on the outer surface of the chassis  3   a , is bent and formed in one side of the igniter replacement door  51 , and a step portion  51   b , which is hooked to the inner surface of the chassis  3   a  via a gasket  55 , is bent and formed in the other side facing the one side of the igniter replacement door  51 . Note that although not shown, the igniter replacement door  51  is screwed so as to be fixed to the chassis  3   a.    
         [0073]    Further, a hook member  52  is vertically erected on the inner surface of the igniter replacement door  51 . As shown in  FIG. 11  and  FIG. 12 , the hook member  52  is bent and formed in a hat shape, and has, at the center thereof, a hook portion  52   a  which engages with the above described claw portion  27   f  of the slider  27 . Further, flange portions  52   b  bent and formed on both sides of the hook portion  52   a  are fixed to the inner surface of the igniter replacement door  51 . Note that the door opening regulating mechanism, which regulates the opening of the igniter replacement door  51 , is configured by the slider  27  and the hook member  52 . 
         [0074]    As shown in  FIG. 6 , when the igniter replacement window  3   d  is closed by the igniter replacement door  51 , the hook portion  52   a  is made to face the direction in which the claw portion  27   f  formed in the slider  27  is moved. Further, as shown in  FIG. 5 , in the state where the lamp replacement window  4   a  is closed by the lamp replacement door  14 , the pressing surface  15   a  of the protection member  15  fixed to the inner surface of the lamp replacement door  14  presses the front surface portion  27   b  of the slider  27 , so as to move the slider  27  into the lamp base  26 . Then, the claw portion  27   f  formed in the slider  27  is engaged with the hook portion  52   a , so that the igniter replacement door  51  is locked in the closed state. 
         [0075]    Meanwhile, in the present embodiment, the igniter replacement door  51  cannot be removed unless the lamp replacement door  14  is opened, but at the time of mounting, only the lamp replacement door  14  can be attached. Therefore, a switch (igniter replacement door opening detection switch)  54 , which detects omission of mounting the igniter replacement door  51 , is provided in the light source apparatus  1 . 
         [0076]    That is, as shown in  FIG. 8 ,  FIG. 9  and  FIG. 11 , the igniter replacement door opening detection switch  54 , which detects the opening of the igniter replacement door  51 , is fixed to the one side of the lamp base  26 . The igniter replacement door opening detection switch  54  is a twin switch having an interlock switch  54   a  and a discharge switch  54   b . In the state where the igniter replacement window  3   d  is closed by the igniter replacement door  51 , the interlock switch  54   a  and the discharge switch  54   b  are respectively turned on and turned off by being pressed by a switch pressing member  53  fixed to the inner surface of the igniter replacement door  51 . In the state where the interlock switch  54   a  is turned on, the connected state between the power source case  6  and the internal electric circuit is maintained. Further, the discharging circuit is interrupted because the discharge switch is turned off. On the other hand, when the igniter replacement door  51  is opened and when the pressing force applied to the igniter replacement door opening detection switch  54  by the switch pressing member  53  is released, the interlock switch  54   a  is turned off, so that the power source circuit is interrupted. Also, the discharge switch  54   b  is turned on, so that the discharging circuit is connected to make the residual voltage of the electric circuit released. 
         [0077]    Further, an insulation sheet  56  is stuck on the inner surface of the igniter replacement door  51 . The insulation sheet  56  is to prevent that in the state where the igniter replacement door  51  is closed, a lead wire projected from the rear surface of the igniter substrate  32  is brought into contact with the igniter replacement door  51 . In this case, a recessed portion for escaping from the lead wire may be provided in the igniter replacement door  51 . A section modulus is increased by forming the recessed portion in the igniter replacement door  51 , so that the strength of the igniter replacement door  51  can be increased. 
         [0078]    Next, there will be described the effect of the present embodiment based on the above described structure. As shown in  FIG. 5 ,  FIG. 8  and  FIG. 11 , in the state where the lamp replacement window  4   a  which is opened on the side surface (in the left side surface in the present embodiment) of the top cover  4  of the apparatus main body  2  is closed by the lamp replacement door  14 , the pressing surface  15   a  formed at the distal end of the protection member  15  fixed to the inner surface of the lamp replacement door  14  presses the slider  27  supported by the lamp base  26 . 
         [0079]    In this state, the claw portion  27   f  formed in the slider  27  is engaged with the hook member  52  fixed to the igniter replacement door  51  closing the igniter replacement window  3   d , so that the igniter replacement door  51  is locked. Therefore, even when the igniter replacement door  51  is attempted to be opened, the igniter replacement door  51  cannot be opened because the hook portion  52   a  is engaged with the claw portion  27   f  of the slider  27 . 
         [0080]    Further, in the igniter replacement door  51 , the step portion  51   b  bent and formed in the side facing the side to which the hook member  52  is fixed, is hooked to the inner surface edge portion of the igniter replacement window  3   d . Thereby, even when the screw fastening the igniter replacement door  51  is removed, the igniter replacement door  51  maintains the state of closing the igniter replacement window  3   d.    
         [0081]    On the other hand, when the igniter  31  is inspected or replaced, the thumb screw  17  screw-fastening the lamp replacement door  14  is first unscrewed from the apparatus main body  2 , to make the lamp replacement door  14  opened. Then, as shown in  FIG. 6 , the pressing force applied to the front surface portion  27   b  of the slider  27  by the pressing surface  15   a  of the protection member  15  fixed to the inner surface of the lamp replacement door  14 , is released. Further, as shown in  FIG. 7 , the pressing force applied to the switch pressing portion  21   a  of the lamp replacement door opening detection switch  21  by the switch pressing member  16  fixed to the inner surface of the lamp replacement door  14 , is released. 
         [0082]    When the pressing force to the switch pressing portion  21   a  of the lamp replacement door opening detection switch  21  is released, the interlock switch provided in the lamp replacement door opening detection switch  21  is turned off, so that the power source circuit is interrupted. Also, the discharge switch is turned on, so that the discharging circuit is connected to make the residual voltage of the electric circuit released. 
         [0083]    Further, when the pressing force to the front surface portion  27   b  of the slider  27  is released, the slider  27  is made to project from the lamp base  26  to the side of the opening window  5   a  formed in the lamp case  5  by the urging force of the return spring  29 . The slider guides  26   e  and  26   f  are arranged on both sides of the slider  27 , and the upper surface  27   a  is arranged close to the ceiling surface  26   d  of the lamp base  26 . Thus, the slider  27  is smoothly moved by being guided by the slider guides  26   e  and  26   f  and the upper surface  27   a.    
         [0084]    Then, as shown in  FIG. 6 ,  FIG. 9  and  FIG. 12 , the claw portion  27   f  formed in the slider  27  is retreated from the hook portion  52   a  of the hook member  52  fixed to the inner surface of the igniter replacement door  51 . This results in the state where the igniter replacement door  51  can be removed. 
         [0085]    Then, the screw (not shown), which fastens the igniter replacement door  51  for closing the igniter replacement window  3   d  opened in the bottom surface of the chassis  3   a  of the main body portion  3 , is unscrewed. At this time, since the claw portion  27   f  of the slider  27  is retreated from the hook portion  52   a  of the hook member  52 , the igniter replacement door  51  can be easily removed. Then, when the igniter replacement door  51  is removed from the igniter replacement window  3   d , there is released the pressing force applied by the switch pressing member  53  fixed to the inner surface of the igniter replacement door  51 , to the interlock switch  54   a  and the discharge switch  54   b  which configure the igniter replacement door opening detection switch  54 . 
         [0086]    As a result, the interlock switch  54   a  is turned off, and the discharge switch  54   b  is turned on. When the interlock switch  54   a  is turned off, the power source circuit already interrupted is doubly interrupted. On the other hand, when the discharge switch  54   b  is turned on, the discharging circuit is connected by another circuit. Note that when the lamp replacement door  14  is opened, the lamp replacement door opening detection switch  21  is operated, so that the power source circuit already interrupted is interrupted, and that the discharging circuit is connected. Thus, the igniter replacement door opening detection switch  54  may be omitted. 
         [0087]    Then, the igniter  31  exposed from the opened igniter replacement window  3   d  is taken out. When the igniter  31  is to be taken out, as shown in  FIG. 14 , the three lock nuts  48  fastening the igniter substrate  32  are unscrewed from the screw portion  33   b  of the support bolt  33 . Then, the igniter substrate  32  is detached from the screw portion  33   b  of the support bolt  33 . In this case, the first and second terminals  42   a  and  42   b  are fastened to the support bolt  33  by the double nut mechanism configured by the second and third nuts  43   a  and  43   b , and hence do not come off even when the lock nut  48  is loosened. 
         [0088]    Thereafter, the igniter substrate  32  is taken out from the igniter replacement window  3   d  which is opened in the chassis  3   a , so as to be subjected to a predetermined inspection. Alternatively, a new igniter substrate  32  is prepared. Then, the igniter substrate  32  subjected to the inspection or the new igniter substrate  32  is housed in the lamp base  26 . When the igniter substrate  32  is to be housed in the lamp base  26 , the screw portion  33   b  of the support bolt  33  is inserted into the hole portion  45   a  of the contact bolt  45  which is fastened to the through hole  32   a  of the igniter substrate  32  via the contact nut  46 . Then, the lock nut  48  is screwed into the screw portion  33   b  projected on the side of the contact nut  46 , so as to be fastened. 
         [0089]    In this case, since the screw portion  45   b  of the contact bolt  45  is slightly projected from the contact nut  46 , even when the lock nut  48  is strongly tightened, the load is transferred only to the second nut  43   b  via the contact bolt  45 . Thus, an unnecessary load is not applied to the igniter substrate  32 . 
         [0090]    Further, in the present embodiment, when the lock nut  48  is loosened, only the igniter substrate  32  is detached, and the fastening state of the first and second terminals  42   a  and  42   b  is maintained. Thereby, the igniter substrate  32  can be easily attached and detached, so that the workability is improved. 
         [0091]    Then, after the igniter substrate  32  is attached to the support bolt  33  at a predetermined position, the igniter replacement door  51  is attached to the igniter replacement window  3   d . Since the insulation sheet  56  is stuck on the inner surface of the igniter replacement door  51 , the lead wire projected from the rear surface of the igniter substrate  32  is prevented from being brought into contact with the inner surface of the igniter replacement door  51 . 
         [0092]    Further, when the igniter replacement door  51  is to be attached to the igniter replacement window  3   d , the lamp replacement door  14  is not yet attached. Thus, the slider  27  is maintained in the projected state and the claw portion  27   f  is in the retreated state, so that the hook member  52  does not interfere with the slider  27 . Thereafter, the igniter replacement door  51  is screwed to the chassis  3   a , so that the igniter replacement window  3   d  is closed. 
         [0093]    Note that when the igniter replacement window  3   d  is closed by the igniter replacement door  51 , the switch pressing member  53  presses the igniter replacement door opening detection switch  54 . Thereby, the interlock switch  54   a  is turned on, so that the power source circuit is connected. Further, the discharge switch  54   b  is turned off, so that the discharging circuit is interrupted. 
         [0094]    Thereafter, the lamp replacement door  14  is attached to the lamp replacement window  4   a , so as to be fixed to the apparatus main body  2  by the thumb screw  17 . Then, the switch pressing member  16  fixed to the inner surface of the lamp replacement door  14  presses the switch pressing portion  21   a  of the lamp replacement door opening detection switch  21  via the leaf spring guide  23 . Thereby, the interlock switch is turned on to make the power source circuit connected. Also, the discharge switch is turned off to make the discharging circuit interrupted. 
         [0095]    Further, the pressing surface  15   a  of the protection member  15  fixed to the inner surface of the lamp replacement door  14  presses the front surface portion  27   b  of the slider  27 , so that the slider  27  is retreated against the urging force of the return spring  29 . Then, the claw portion  27   f  formed in the slider  27  is engaged in the hook portion  52   a  of the hook member  52  fixed to the inner surface of the igniter replacement door  51 , so that the igniter replacement door  51  is locked in the closed state. 
         [0096]    In this way, the present embodiment is configured such that the igniter replacement door  51  is never opened unless the lamp replacement door  14  is opened. Thus, when the lamp replacement door  14  is opened, the interlock switch configuring the lamp replacement door opening detection switch  21  is turned off to make the power source circuit interrupted. Also, the discharge switch is turned on to make the discharging circuit connected. Thus, the interlock switch and the discharge switch on the side of the igniter replacement door  51  need not be provided in principle. Thereby, the reduction in the number of components and the simplification of electrical wiring and structure can be realized, so that the assembling is facilitated. 
         [0097]    Further, the first and second terminals  42   a  and  42   b  are fastened to the support bolt  33  supporting the igniter substrate  32 , by the double nut mechanism configured by the second and third nuts  43   a  and  43   b . Thus, even when the igniter substrate  32  is detached from the support bolt  33 , the first and second terminals  42   a  and  42   b  are prevented from coming off. Thereby, the igniter substrate  32  can be easily attached and detached, so that the workability is improved. 
       Second Embodiment 
       [0098]      FIG. 15  to  FIG. 20  show a second embodiment according to the present invention. Note that components which are the same as those of the first embodiment are denoted by the same reference numerals and characters, and the explanation thereof is omitted. 
         [0099]    The above described first embodiment is configured such that even when the igniter replacement door  51  is opened, only the lamp replacement door  14  can be closed. However, the present embodiment is configured such that a door closing regulation mechanism is provided, and that in the state where the igniter replacement door  51  is opened, the closing of the lamp replacement door  14  is prevented by the door closing regulation mechanism. 
         [0100]    That is, the door closing regulation mechanism  60  has a guide cylinder portion  61  which is formed integrally with the lamp base  26  in the state of being erected vertically to the lamp base  26 . The guide cylinder portion  61  is vertically erected at a position to face the hook portion  52   a  of the hook member  52  in the state where the igniter replacement door  51  is closed. The lower end of the guide cylinder portion  61  is opened in the ceiling surface  26   d  of the lamp base  26 . 
         [0101]    A stopper main body  62  as a regulation member is inserted in the guide cylinder portion  61  so as to be freely moved forward and backward. The stopper main body  62  has a cylindrical shape, and a flat surface  62   a  is formed on one side along the side surface of the stopper main body  62 . A hook portion  62   b  is formed stepwise in the upper portion of the flat surface  62   a . Further, a curved surface portion  62   c , which is curved toward the lower end direction from the side of the flat surface  62   a , is formed in the lower portion of the stopper main body  62 . Further, the flat surface  62   a  is arranged so as to face the side of the lamp replacement window  4   a.    
         [0102]    Further, as shown in  FIG. 20 , the opening portion formed in the ceiling surface  26   d  at the guide cylinder portion  61  is formed in substantially the same shape as the shape of the portion of the stopper main body  62 , in which the flat surface  62   a  is formed, that is, in a shape formed by flattening a part of a circular shape. Thereby, the circumferential rotation about the axis of the stopper main body  62  is regulated by the supporting surface  61   a  which is brought into slide contact with the flat surface  62   a.    
         [0103]    A seat surface  61   b , which receives the hook portion  62   b  formed in the stopper main body  62 , is formed at the upper end of the supporting surface  61   a . As shown in  FIG. 19 , in the state where the hook portion  62   b  of the stopper main body  62  is hooked on the seat surface  61   b , the distal end of the stopper main body  62  is projected downward from the ceiling surface  26   d  of the lamp base  26 , so that the distal end of the slider  27  is arranged to face the flat surface  62   a  formed on the stopper main body  62 . Further, a compression spring  63 , which presses downward the stopper main body  62 , is provided between the upper surface of the stopper main body  62  and the internal upper surface of the guide cylinder portion  61 . 
         [0104]    Note that as shown in  FIG. 17 , the slider guides  26   e  and  26   f  are extended to the inner wall on the side of the guide hole portion  26   a , and an escape portion is formed at a portion corresponding to the inner circumference of the guide cylinder portion  61 . Thereby, as shown in  FIG. 18 , even when the slider  27  is projected to the outside of the lamp base  26 , the movement of the slider  27  in the width direction thereof can be regulated. 
         [0105]    In this configuration, as shown in  FIG. 15  and  FIG. 17 , in the state where both the igniter replacement door  51  and the lamp replacement door  14  are closed, there is maintained a state in which the stopper main body  62  provided in the door closing regulation mechanism  60  is pushed upward by being brought into slide contact with the upper surface  27   a  of the slider  27 . 
         [0106]    Further, when the lamp replacement door  14  is opened in this state as shown in  FIG. 16 , the slider  27  is projected by the urging force of the return spring  29  (see  FIG. 18 ), so that the rear end of the slider  27  is separated from the lower end of the stopper main body  62  of the door closing regulation mechanism  60 . Thereby, the lower end of the stopper main body  62  is brought into contact with the upper surface of the hook portion  52   a  of the hook member  52  by the urging force of the compression spring  63 . Further, the claw portion  27   f  of the slider  27  is separated from the hook portion  52   a  of the hook member  52  fixed to the igniter replacement door  51 , and hence the igniter replacement door  51  is permitted to be removed. 
         [0107]    Then, as shown in  FIG. 19 , when the igniter replacement door  51  is opened, the stopper main body  62  is further slid downward by the urging force of the compression spring  63 . Thereby, the hook portion  62   b  formed in the stopper main body  62  is hooked on the seat surface  61   b  formed in the guide cylinder portion  61 , so that the downward movement is regulated. Then, the flatly formed guide surface  62   a  of the stopper main body  62  is arranged to face the rear end of the slider  27 , so that the retreating direction (the movement in the right direction in  FIG. 19 ) of the slider  27  is regulated. 
         [0108]    When the lamp replacement door  14  is attempted to be closed without the igniter replacement door  51  being closed in this state, the pressing surface  15   a  of the protection member  15  fixed to the lamp replacement door  14  presses the front surface portion  27   b  of the slider  27 . However, the rear end of the slider  27  is brought into contact with the guide surface  62   a  of the stopper main body  62  so that the movement of the slider  27  is regulated. Thus, the lamp replacement door  14  cannot be closed. 
         [0109]    On the other hand, when the igniter replacement door  51  is closed, the distal end of the stopper main body  62  is pushed up by the upper surface of the hook portion  52   a  of the hook member  52  fixed to the igniter replacement door  51  against the urging force of the compression spring  63 . Therefore, in this case, the hook portion  52   a  functions as a pressing portion. 
         [0110]    Then, as shown in  FIG. 16 , when the igniter replacement door  51  is closed, the curved surface portion  62   c  of the stopper main body  62 , the lower end of whose curved surface portion is brought into contact with the hook portion  52   a , is arranged to face the rear end of the slider  27 . 
         [0111]    Therefore, when the lamp replacement door  14  is closed in this state, the pressing surface  15   a  of the protection member  15  presses the front surface portion  27   b  of the slider  27 , so as to make the slider  27  retreat. Then, the rear end of the slider  27  pushes up the curved surface portion  62   c  of the stopper main body  62 , to make the stopper main body  62  retreat to the position which permits the lamp replacement door  14  to be closed. Also, the rear end of the slider  27  enters between the hook portion  52   a  and the lower end of the stopper main body  62 , to permit the slider  27  to easily retract. As a result, the lamp replacement door  14  can be closed. 
         [0112]    In this way, in the present embodiment, there is provided the stopper main body  62  which is pushed up by the hook member  52  fixed to the igniter replacement door  51 . Thereby, in the state where the igniter replacement door  51  is opened, the closing of the lamp replacement door  14  is regulated, so that it is possible to prevent the closing of the igniter replacement door  51  from being forgotten. Therefore, in the present embodiment, it is possible to eliminate the igniter replacement door opening detection switch  54  which is provided in the lamp base  26  in the first embodiment. 
         [0113]    Having described the preferred embodiments of the invention referring to the accompanying drawings, it should be understood that the present invention is not limited to those precise embodiments and various changes and modifications thereof could be made by one skilled in the art without departing from the spirit or scope of the invention as defined in the appended claims.