Patent Publication Number: US-8994268-B2

Title: Strobe device

Description:
This application is a U.S. National Phase Application of PCT International Application PCT/JP2012/004973. 
     TECHNICAL FIELD 
     The present invention relates to a strobe device used for taking pictures or other purposes. 
     BACKGROUND ART 
     Conventional well-known strobe devices include the following components: a flash discharge tube having an anode on one side and a cathode on the other side; a reflector storing a part of the flash discharge tube; and a trigger coil having a cylindrical core and primary winding and secondary winding wound around the core. 
     In the above strobe devices, the trigger coil is disposed near the reflector, and the trigger coil has a secondary terminal (output terminal), which is in contact with the reflector (see, for example, Patent Literatures 1 and 2). According to these Patent Literatures, this configuration eliminates the need to provide a lead wire connecting the reflector and the trigger coil, thereby eliminating illumination failure due to the imperfect contact of the lead wire. 
     In the strobe device of Patent Literature 1, the trigger coil is disposed behind the reflector, whereas in the strobe device of Patent Literature 2, the trigger coil is disposed under the reflector. 
     Because of these arrangements, the strobe devices of Patent Literatures 1 and 2 are far from being compact. 
     CITATION LIST 
     Patent Literature 
     
         
         
           
             Patent Literature 1: Japanese Unexamined Patent Publication No. H10-186466 
             Patent Literature 2: Japanese Unexamined Patent Publication No. 2004-334100 
           
         
       
    
     SUMMARY OF THE INVENTION 
     The present invention is directed to provide a strobe device including the following components: a flash discharge tube having an anode on one side thereof and a cathode on the other side thereof; a conductive reflector composing a trigger external electrode, which is in in contact with a part of the flash discharge tube and stores the part; a trigger coil having a hollow core, and a primary winding and a secondary winding wound around the core; and a conductor connecting the secondary winding of the trigger coil and the reflector. The trigger coil has an end of the flash discharge tube inserted into the core, and includes, at an end thereof adjacent to the reflector, a secondary terminal connected to the secondary winding. The reflector has a bottom in contact with the outer peripheral surface of the flash discharge tube, the outer peripheral surface covering at least the region extending from the anode to the cathode. The conductor has a first contact portion in contact with the secondary terminal of the trigger coil, and a second contact portion in contact with the bottom of the reflector. 
     This configuration provides a compact and thin strobe device. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a strobe device according to an exemplary embodiment of the present invention. 
         FIG. 2  is a sectional view of the strobe device according to the exemplary embodiment taken along line  2 - 2  of  FIG. 1 . 
         FIG. 3  is an exploded perspective view of the strobe device according to the exemplary embodiment. 
         FIG. 4  is an exploded perspective view of an essential part of the strobe device according to the exemplary embodiment. 
         FIG. 5A  is a perspective view of the essential part of the strobe device according to the exemplary embodiment. 
         FIG. 5B  is a front view of the essential part of the strobe device according to the exemplary embodiment. 
         FIG. 6A  is a front view showing the arrangement of a flash discharge tube and a reflector of the strobe device according to the exemplary embodiment. 
         FIG. 6B  is a perspective view showing the arrangement of the flash discharge tube and the reflector of the strobe device according to the exemplary embodiment. 
         FIG. 7A  is a perspective view of a trigger coil of the strobe device according to the exemplary embodiment. 
         FIG. 7B  is a perspective view of the trigger coil of the strobe device according to the exemplary embodiment viewed in a different direction. 
     
    
    
     DESCRIPTION OF EMBODIMENT 
     A strobe device according to an exemplary embodiment of the present invention will now be described with reference to drawings. Note that the present invention is not limited to the following exemplary embodiment. 
     EXEMPLARY EMBODIMENT 
     The strobe device according to the exemplary embodiment of the present invention will now be described with reference to  FIGS. 1 to 7B . 
     First, the schematic configuration of the strobe device of the exemplary embodiment of the present invention will be described with reference to  FIGS. 1 to 3 . 
       FIG. 1  is a perspective view of the strobe device according to the exemplary embodiment.  FIG. 2  is a sectional view of the strobe device according to the exemplary embodiment taken along line  2 - 2  of  FIG. 1 .  FIG. 3  is an exploded perspective view of the strobe device according to the exemplary embodiment. 
     As shown in  FIG. 1 , strobe device  1  of the exemplary embodiment includes base  6 , and optical panel  8  engaged with base  6 . Strobe device  1  further includes primary terminal  23  and common terminal  24  of a trigger coil (not shown), and anode terminal  32 , all of which are external terminals projecting outside strobe device  1 . 
     As shown in  FIGS. 2 and 3 , strobe device  1  of the exemplary embodiment stores at least flash discharge tube  2  for emitting light, conductive reflector  3 , trigger coil  4 , and conductor  5 . Reflector  3  stores a part of flash discharge tube  2 , thereby functioning as a trigger external electrode of flash discharge tube  2 . Trigger coil  4  is disposed on other side  2 B of flash discharge tube  2  in such a manner that primary terminal  23  and common terminal  24  project outside strobe device  1 . Conductor  5  electrically connects reflector  3  and trigger coil  4 . 
     Base  6  is made of an insulating material such as polycarbonate. As shown in  FIG. 3 , base  6  includes holding portion  30  for holding below-described second contact portion  28  of conductor  5  so as to store reflector  3 . Base  6  also includes fixing part  7  for fixing one side  2 A of flash discharge tube  2  to base  6 . Fixing part  7  has connecting portion  31  which is configured to be connected to anode  10  of flash discharge tube  2 , and plate-shaped anode terminal  32  which is electrically connected to connecting portion  31  and is projecting as an external terminal. Connecting portion  31  is bonded by, for example, soldering to anode  10  of flash discharge tube  2 . 
     Optical panel  8 , which is made of a light transmitting material such as PMMA, covers reflector  3  so as to store it. 
     As shown in  FIG. 2 , flash discharge tube  2  includes tubular glass bulb  9 , anode  10  disposed on one side  2 A, and cathode  11  disposed on other side  2 B. Glass bulb  9  is filled with a rare gas such as xenon at a predetermined pressure. When electrons collide with the rare gas, flash discharge tube  2  generates and emits light to illuminate a subject. Anode  10  is a bar-shaped electrode made, for example, of tungsten. Anode  10  is inserted into glass bulb  9  and fixed at one side  2 A by being melted with glass beads (not shown). Cathode  11  is formed of bar-shaped electrode  12  and metal sintered body  13 . Bar-shaped electrode  12  is made, for example, of tungsten, and is inserted into glass bulb  9  and fixed at other side  2 B by being melted with glass beads (not shown). Metal sintered body  13  is made of a mixture of metal fine powder, such as a mixture of tungsten and tantalum or a mixture of tantalum and nickel. Metal sintered body  13  is fixed to bar-shaped electrode  12  at the end inside glass bulb  9 . 
     The following is a detailed description, with reference to  FIGS. 5A to 7B , of the configuration of reflector  3  and trigger coil  4  of strobe device  1  according to the exemplary embodiment. 
       FIG. 5A  is a perspective view of the essential part of the strobe device according to the exemplary embodiment according to the exemplary embodiment.  FIG. 5B  is a front view of the essential part of the strobe device according to the exemplary embodiment.  FIGS. 6A and 6B  are a front view and a perspective view, respectively, showing the arrangement of the flash discharge tube and the reflector of the strobe device according to the exemplary embodiment.  FIGS. 7A and 7B  are perspective views of the trigger coil of the strobe device viewed in different directions from each other according to the exemplary embodiment. 
     As shown in  FIGS. 5A to 6B , reflector  3  has bottom  14 , opening  15 , side reflective portion  16 , and recessed installation portion  17 . Bottom  14  of reflector  3  is configured to be in contact with the outer peripheral surface of flash discharge tube  2 . This allows reflector  3  to function as a trigger external electrode of flash discharge tube  2 . Opening  15  passes the light emitted from flash discharge tube  2  to the outside. Side reflective portion  16  reflects the light emitted from flash discharge tube  2  toward opening  15 . Installation portion  17  stores flash discharge tube  2 . 
     Bottom  14  of reflector  3  is formed of base portion  18  and extension  19 . Base portion  18  is configured to be in contact with the outer peripheral surface of flash discharge tube  2  so as to cover the region extending from anode  10  to cathode  11 . Base portion  18  has a shape of an arc having substantially (or exactly) the same radius as glass bulb  9  so that base portion  18  can be in surface contact with the outer peripheral surface of glass bulb  9 . This configuration allows base portion  18  to function as a reflective plate for reflecting the light emitted from flash discharge tube  2 , and also as a trigger external electrode of flash discharge tube  2 . 
     Extension  19  extends from base portion  18  of bottom  14  toward other side  2 B of flash discharge tube  2  in the axial (longitudinal) direction so as to be in contact with the outer peripheral surface of flash discharge tube  2 , thereby covering metal sintered body  13  of cathode  11 . Extension  19  has a shape of an arc having substantially (or exactly) the same radius as glass bulb  9  so as to be in surface contact with the outer peripheral surface of glass bulb  9 . This configuration allows extension  19  to function as a trigger external electrode of flash discharge tube  2  in the same manner as base portion  18 . 
     As shown in  FIGS. 7A and 7B , trigger coil  4  includes hollow cylindrical core  20 , and primary winding  21  and secondary winding  22  wound around core  20 . Core  20  is formed of a magnetic body such as ferrite. As shown in  FIG. 2 , primary winding  21  is on the other side (on the primary terminal  23  side) of core  20  of trigger coil  4 , whereas secondary winding  22  is on one side of core  20  of trigger coil  4 , that is, on the side adjacent to reflector  3  opposite to core  20 . One end  22 A of secondary winding  22  is connected to other end  21 B of primary winding  21 . 
     Trigger coil  4  further includes primary terminal  23  connected to one end  21 A of primary winding  21 ; common terminal  24  connected to other end  21 B of primary winding  21  and to one end  22 A of secondary winding  22 ; and secondary terminal  25  connected to other end  22 B of secondary winding  22 . Common terminal  24  is electrically connected also to cathode  11  of flash discharge tube  2 . 
     As best shown in  FIGS. 1 and 5A , primary terminal  23  and common terminal  24  of trigger coil  4  are bar-shaped, projecting to the outside and are connected as external terminals to, for example, an external driving circuit (not shown). Secondary terminal  25 , on the other hand, has an annular plate shape and is disposed at an end of trigger coil  4  (in the axial direction of core  20 ), that is, the end adjacent to reflector  3  as shown in  FIG. 7B . 
     As shown in  FIG. 2 , hollow core  20  has locking member  26  for positioning flash discharge tube  2  in the axial (longitudinal) direction. Locking member  26  projects inside in the radial direction of core  20 , thereby locking the end of flash discharge tube  2  on other side  2 B. In core  20 , a portion of bar-shaped electrode  12  on other side  2 B leading up to metal sintered body  13  of cathode  11  melted after being inserted into glass bulb  9  on other side  2 B of flash discharge tube  2  is inserted until reaching locking member  26 . Thus, the portion of cathode  11  not including metal sintered body  13  can be surely inserted into core  20  of trigger coil  4 . 
     Next, the configuration of conductor  5  of strobe device  1  according to the exemplary embodiment will now be described in detail based on  FIG. 4  with reference to  FIGS. 2 and 5B . 
       FIG. 4  is an exploded perspective view of the essential part of the strobe device according to the exemplary embodiment. 
     As shown in  FIG. 4 , conductor  5  includes first contact portion  27 , and second contact portion  28  connected to first contact portion  27 , both of which are, for example, plate-shaped. First contact portion  27  is configured to be in contact with secondary terminal  25  of trigger coil  4 , whereas second contact portion  28  is configured to be in contact with bottom  14  of reflector  3 . This configuration establishes an electrical connection between secondary terminal  25  of trigger coil  4  and bottom  14  of reflector  3  via conductor  5 . 
     First contact portion  27  of conductor  5  has insertion portion  29  of, for example, a substantial (or exact) U shape so as to pass flash discharge tube  2  through it and into trigger coil  4 . First contact portion  27  of conductor  5  has a curved shape such as an arc, and the convex portion of the curve is in contact with secondary terminal  25  of trigger coil  4 . 
     Second contact portion  28  of conductor  5 , on the other hand, has a belt shape extending in the axial (longitudinal) direction of flash discharge tube  2  and is curved like an arc protruding toward bottom  14  of reflector  3 . 
     As shown in  FIG. 2 , trigger coil  4  is inserted into other side  2 B of flash discharge tube  2  through conductor  5 , and flash discharge tube  2  stored in reflector  3  is laid between base  6  and optical panel  8 . As a result, second contact portion  28  of conductor  5  elastically deforms between bottom  14  of reflector  3  and base  6 . Because of the restoring force (biasing force) due to the elastic deformation of second contact portion  28  of conductor  5 , second contact portion  28  can be in contact with bottom  14  of reflector  3 , and flash discharge tube  2  and other components can be held in base  6  and optical panel  8 . 
     As described above, base  6  includes holding portion  30  for holding second contact portion  28 . Holding portion  30  sandwiches second contact portion  28  between bottom  14  of reflector  3  and itself. 
     The strobe device of the exemplary embodiment is configured as described above. The operation and action of strobe device  1  of the exemplary embodiment will now be described as follows. 
     First, a driving voltage is applied from an external driving circuit (not shown) to anode  10  and cathode  11  of flash discharge tube  2  via anode terminal  32  and common terminal  24 , which are external terminals of strobe device  1 . 
     At the same time as the application of the voltage or after a predetermined amount of time, a pulse-like voltage is applied from the external driving circuit (not shown) to primary winding  21  of trigger coil  4  via primary terminal  23  and common terminal  24 , which are external terminals of strobe device  1 . The voltage applied to primary winding  21  is, for example, boosted at secondary winding  22 . The boosted voltage is applied as a trigger pulse to bottom  14  of reflector  3  from secondary terminal  25  of trigger coil  4  via first and second contact portions  27  and  28  of conductor  5 . 
     This activates and ionizes the rare gas filled in glass bulb  9  near the inner periphery of glass bulb  9  which is in contact with base portion  18  and extension  19  of bottom  14  of reflector  3 . 
     Cathode  11  also emits electrons toward anode  10  so as to promote the ionization of the rare gas, making the rare gas more conductive. This causes a sudden large current flow from anode  10  to cathode  11 , allowing flash discharge tube  2  to emit light to illuminate the outside. 
     At this moment, the trigger pulse is applied also to extension  19  of bottom  14  of reflector  3  covering metal sintered body  13  of cathode  11 . The pulse application allows electrons emitted from cathode  11  to stably form a discharge path starting from the vicinity of cathode  11 . This reduces variations in the amount of light emitted from flash discharge tube  2 , thereby irradiating the subject in a stable manner. 
     The present invention is not limited to the above-described exemplary embodiment and can be properly changed within the range not deviating from the spirit of the present invention. It also goes without saying that the configuration and methods of the following various modified examples can be arbitrary selected and adopted into the above-described exemplary embodiment. 
     For example, flash discharge tube  2  has no thin-film transparent electrode on its surface in the exemplary embodiment, but may alternatively have a thin-film transparent electrode such as an ITO or NESA film formed thereon. In this case, too, at least the region extending from anode  10  to cathode  11  of flash discharge tube  2 , and metal sintered body  13  can be covered by bottom  14  of reflector  3 , which is in contact with the outer peripheral surface of the glass bulb of flash discharge tube  2  having the thin-film transparent electrode formed thereon. This reduces variations in the amount of light emitted from flash discharge tube  2 , thereby irradiating the subject in a stable manner. 
     Extension  19  of reflector  3  is arc-shaped in the exemplary embodiment, but may alternatively be, for example, flat-shaped. In this case, too, the discharge path of the electrons emitted from cathode  11  can be formed stably from the vicinity of cathode  11 . 
     First contact portion  27  of conductor  5  is a substantial U shape with insertion portion  29  inside in the exemplary embodiment, but may alternatively be, for example, a ring shape, that is, a substantial (or exact) O shape with insertion portion  29  as an opening in the center. This improves the accuracy of positioning first contact portion  27  relative to flash discharge tube  2 . 
     Second contact portion  28  of conductor  5  is curved like an arc in the longitudinal direction in the exemplary embodiment, but may alternatively have, for example, a plurality of peaks and troughs in the longitudinal direction, that is, corrugated. This configuration improves the contact between bottom  14  of reflector  3  and glass bulb  9  of flash discharge tube  2 . 
     As described hereinbefore, strobe device  1  of the present invention includes flash discharge tube  2  having anode  10  on one side thereof and cathode  11  on the other side thereof; conductive reflector  3  composing a trigger external electrode, which is in contact with a part of flash discharge tube  2  and stores the part; trigger coil  4  having hollow core  20 , and primary winding  21  and secondary winding  22  wound around core  20 ; and conductor  5  connecting secondary winding  22  of trigger coil  4  and reflector  3 . Trigger coil  4  has an end of flash discharge tube  2  inserted into core  20 , and includes, at an end thereof adjacent to reflector  3 , secondary terminal  25  connected to secondary winding  22 . Reflector  3  has bottom  14  in contact with the outer peripheral surface of flash discharge tube  2 , the outer peripheral surface covering at least the region extending from anode  10  to cathode  11 . Conductor  5  has first contact portion  27  in contact with secondary terminal  25  of trigger coil  4 , and second contact portion  28  in contact with bottom  14  of reflector  3 . 
     In this configuration, the end of flash discharge tube  2  is inserted into core  20  of trigger coil  4 , and secondary terminal  25  electrically connected to secondary winding  22  is disposed at that end, which is adjacent to reflector  3 , of trigger coil  4 . This configuration allows strobe device  1  to be compact and thin. 
     Bottom  14  of reflector  3  is in contact with the outer peripheral surface of flash discharge tube  2  so as to cover at least the region extending from anode  10  to cathode  11  of flash discharge tube  2 . First contact portion  27  of conductor  5  is in contact with secondary terminal  25  of trigger coil  4 . Second contact portion  28  of conductor  5  connected to first contact portion  27  elastically deforms and holds bottom  14  of reflector  3  and flash discharge tube  2  in such a manner that reflector  3  and flash discharge tube  2  are in contact with each other. This ensures the electrical connection between secondary terminal  25  of trigger coil  4  and bottom  14  of reflector  3  via conductor  5 . This also greatly reduces the connection distance between flash discharge tube  2  and secondary terminal  25 , which outputs a trigger pulse. This configuration eliminates the power loss caused by the resistance of a lead wire used for connection as in the conventional strobe devices. 
     In strobe device  1  of the present invention, first contact portion  27  of conductor  5  includes insertion portion  29  into which flash discharge tube  2  is inserted, and second contact portion  28  of conductor  5  has a curved belt shape extending in the longitudinal direction of flash discharge tube  2 . 
     In this configuration, flash discharge tube  2  is inserted into insertion portion  29  formed in first contact portion  27  of conductor  5 , thereby allowing first contact portion  27  to be positioned relative to flash discharge tube  2 . Furthermore, second contact portion  28  of conductor  5  is shaped like a belt extending along flash discharge tube  2  and is also curved in the longitudinal direction of flash discharge tube  2 . As a result, second contact portion  28  of conductor  5  can elastically deform, allowing bottom  14  of reflector  3  to be held in contact with flash discharge tube  2 . 
     In strobe device  1  of the present invention, cathode  11  of flash discharge tube  2  includes metal sintered body  13  at an end thereof. 
     In strobe device  1  of the present invention, flash discharge tube  2  is inserted at a portion thereof into core  20  of trigger coil  4 , the portion being on the cathode  11  side of flash discharge tube  2  and not including metal sintered body  13 . 
     In the strobe device of the present invention, bottom  14  of reflector  3  is disposed to further cover metal sintered body  13  of flash discharge tube  2 . 
     Thus, metal sintered body  13  is formed at an end of cathode  11 , and the portion of flash discharge tube  2  which does not contain metal sintered body  13  is inserted into core  20  of trigger coil  4 . This configuration allows strobe device  1  to be compact and thin. 
     When a voltage is applied between anode  10  and cathode  11  of flash discharge tube  2 , and a trigger pulse is applied to bottom  14  of reflector  3 , a uniform electron flow is generated between anode  10  and cathode  11  of flash discharge tube  2 . In this case, bottom  14  of reflector  3  which is in contact with the outer peripheral surface of flash discharge tube  2  covers not only the region extending from anode  10  to cathode  11 , but also metal sintered body  13  of cathode  11 . In this case, the discharge path of the electrons emitted from cathode  11  can be formed stably from the vicinity of cathode  11 . This reduces variations in the amount of light emitted from flash discharge tube  2 , thereby irradiating the subject in a stable manner. 
     INDUSTRIAL APPLICABILITY 
     The compact strobe device of the present invention is useful for irradiating a subject to take pictures of. 
     REFERENCE MARKS IN THE DRAWINGS 
     
         
           1  strobe device 
           2  flash discharge tube 
           2 A one side 
           2 B other side 
           3  reflector 
           4  trigger coil 
           5  conductor 
           6  base 
           7  fixing part 
           8  optical panel 
           9  glass bulb 
           10  anode 
           11  cathode 
           12  bar-shaped electrode 
           13  metal sintered body 
           14  bottom 
           15  opening 
           16  side reflective portion 
           17  installation portion 
           18  base portion 
           19  extension 
           20  core 
           21  primary winding 
           21 A,  22 A one end 
           21 B,  22 B other end 
           22  secondary winding 
           23  primary terminal 
           24  common terminal 
           25  secondary terminal 
           26  locking member 
           27  first contact portion 
           28  second contact portion 
           29  insertion portion 
           30  holding portion 
           31  connecting portion 
           32  anode terminal