Patent Publication Number: US-6986535-B2

Title: Latch device

Description:
BACKGROUND OF THE INVENTION AND RELATED ART STATEMENT 
   The present invention relates to a latch device. The latch device is provided with a switch and is attached to an attached member such as a main member of a radio cassette player, so that a door member of the radio cassette is closed or opened when the door member is pushed. 
   A conventional latch device includes a movable member and a housing. The movable member is urged with an urging member to a position where a part of the movable member projects from the housing. When the movable member is pushed into the housing against a force of the urging member, the movable member is locked at a push-in position where a push-push type lock mechanism turns to a locked state and the switch is turned on. When the movable member in the push-in position is pushed into the housing again against the force of the urging member, the lock mechanism turns to an unlocked state, so that the movable member is returned to the projecting position and the switch is turned off (refer to Patent Reference 1).
         Patent Reference 1: Japanese Utility Model No. 7-14062       

   In the latch device disclosed in Patent Reference 1, the lock mechanism is provided only on one side (front or back surface) of the movable member. Accordingly, due to a single lock mechanism, strength of locking the movable member is not strong enough. Also, the switch is provided on a surface of the movable member opposite to a surface where the lock mechanism is provided. Therefore, it is difficult to make a width of the latch device small. 
   In view of the problems described above, the present invention has been made, and an object of the present invention is to provide a latch device for locking with higher locking strength through two lock mechanisms. It is also possible to make a width of the latch small by providing the switches on both sides of the movable member. 
   Further objects and advantages of the invention will be apparent from the following description of the invention. 
   SUMMARY OF THE INVENTION 
   According to the present invention, a latch device includes a movable member and a housing. The movable member is urged with an urging member to a position where a part of the movable member projects from the housing. When the movable member is pushed into the housing against a force of the urging member, a push-push type lock mechanism turns to a locked state and the movable member is locked at a push-in position. At this time, the switch is turned on or turned off. When the movable member in the push-in position is pushed into the housing again against the force of the urging member, the lock mechanism turns to an unlocked state, so that the movable member is returned to the projecting position. At this time, the switch is turned on or turned off. The lock mechanism is provided on front and back surfaces of the movable member as well as on portions of the housing facing the front and back surfaces of the movable member. 
   According to the present invention, the switch may be provided on the front and back surfaces of the movable member as well as on portions of the housing facing the front and back surfaces of the movable member. Terminals composing the switch provided on the front and back surfaces of the movable member may be electrically connected. The terminals provided on the front and back surfaces of the movable member may be formed in a U-shape seen from a direction that the movable member is pushed in. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a plan view of a housing composing a latch device according to an embodiment of the present invention; 
       FIG. 2  is a front view of the housing shown in  FIG. 1 ; 
       FIG. 3  is a right side view of the housing shown in  FIG. 1 ; 
       FIG. 4  is a left side view of the housing shown in  FIG. 1 ; 
       FIG. 5  is a cross sectional view taken along line  5 — 5  in  FIG. 2 ; 
       FIG. 6  is a cross sectional view taken along line  6 — 6  in  FIG. 2 ; 
       FIG. 7  is a cross sectional view taken along line  7 — 7  line in  FIG. 4 ; 
       FIG. 8  is a plan view of a movable member composing the latch device according to the embodiment of the present invention; 
       FIG. 9  is a front view of the movable member shown in  FIG. 8 ; 
       FIG. 10  is a right side view of the movable member shown in  FIG. 8 ; 
       FIG. 11  is a left side view of the movable member shown in  FIG. 8 ; 
       FIG. 12  is a bottom plan view of the movable member shown in  FIG. 8 ; 
       FIG. 13  is a cross sectional view taken along line  13 — 13  in  FIG. 11 ; 
       FIG. 14  is a plan view of a guide lever composing the latch device according to the embodiment of the present invention; 
       FIG. 15  is a front view of the guide lever shown in  FIG. 14 ; 
       FIG. 16  is a plan view of a fixed terminal composing the latch device according to the embodiment of the present invention; 
       FIG. 17  is a front view of the fixed terminal shown in  FIG. 16 ; 
       FIG. 18  is a plan view of a movable terminal composing the latch device according to the embodiment of the present invention; 
       FIG. 19  is a front view of the movable terminal shown in  FIG. 18 ; 
       FIG. 20  is a right side view of the movable terminal shown in  FIG. 18 ; 
       FIG. 21  is a view for explaining an operation of the latch device according to the embodiment of the present invention; 
       FIG. 22  is a view for explaining an operation of the latch device according to the embodiment of the present invention; 
       FIG. 23  is a view for explaining an operation of the latch device according to the embodiment of the present invention; 
       FIG. 24  is a view for explaining an operation of the latch device according to the embodiment of the present invention; and 
       FIG. 25  is a view for explaining an operation of the latch device according to the embodiment of the present invention. 
   

   DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
   Hereunder, embodiments of the present invention will be explained with reference to the accompanying drawings.  FIG. 1  is a plan view of a housing composing a latch device according to an embodiment of the present invention.  FIG. 2  is a front view of the housing shown in  FIG. 1 ;  FIG. 3  is a right side view of the housing shown in  FIG. 1 ; and  FIG. 4  is a left side view of the housing shown in  FIG. 1 .  FIG. 5  is a cross sectional view taken along line  5 — 5  in  FIG. 2 ;  FIG. 6  is a cross sectional view taken along line  6 — 6  in  FIG. 2 ; and  FIG. 7  is a cross sectional view taken along line  7 — 7  in  FIG. 4 . A guide groove communicating with a guide long hole is shown at an upper left of  FIG. 7 . Hereinafter, up and down directions, and right and left directions correspond to the front view of each member. 
   In  FIGS. 1 to 7 , a housing  11  is formed of a synthetic resin. The housing  11  is composed of a box portion  12  having a front surface wall  12   f , a back surface wall  12   b , a ceiling wall  12   u , a bottom wall  12   d , and a left side surface wall  121 ; and a short frame portion  24  extending from the ceiling wall  12   u  and the bottom wall  12   d  at the right side of the box portion  12  and having a height same as that of the box portion  12  and a width larger than that of the box portion  12 . Accordingly, the housing  11  has an opening at one end thereof (right side, right surface wall) 
   In the box portion  12 , elastic supporting pieces  13  are formed on the front surface wall  12   f  and the back surface wall  12   b  at a side of the frame portion  24 , and extend from the left side surface wall  121  to one end of the box portion  12  for sandwiching an attached member with the frame portion  24 . A first cam projecting bar  14 A and a second cam bar  14 B are formed on an inner surface of the front surface wall  12   f  at a side of the left side surface wall  121 . The first cam projecting bar  14 A and second cam bar  14 B horizontally extend in parallel from the left side surface wall  121  to the end of the box portion  12  with an interval in which a flat plate  40  of the movable member  31  is fit to move. 
   A rectangular long guide hole  15  extending from the left side surface wall  121  toward the end of the box portion  12  up to the frame portion  24  is formed on the ceiling wall  12   u  at a side of the front surface wall  12   f  and a side of the end of the box portion  12  (right side surface). Engagement pieces  16  extending from the left side surface wall  121  toward the end of the box portion  12  are formed on the ceiling wall  12   u  and the bottom wall  12   d  at a side of the back surface wall  12   b  near the left side surface wall  121 . 
   A guide groove  15   a  connected to the guide long hole  15  is formed on an inner surface of the ceiling of the frame portion  24 , and reaches a right side edge of the frame portion  24 . An engagement projection  16   a  projecting slightly into the box portion  12  is formed on each of the engagement pieces  16  for engaging an engagement hole  72   h  of a fixed terminal  71 . 
   In the box portion  12 , holding pieces  17  are formed on the inner surfaces of the ceiling wall  12   u  and the bottom wall  12   d  at positions extending from the engagement pieces  16  for holding ends of the fixed terminals  71  with the ceiling wall  12   u  and the bottom wall  12   d . A spring receiver  18  is formed on the inner surface of the left side surface wall  121  between the engagement pieces  16  for positioning a coil spring  51  as an urging member (described later), and extends toward the end of the box portion  12  parallel to the ceiling wall  12   u  and the left side surface wall  12   d . Insertion holes  19  are formed on the inner surface of the left side surface wall  121  at a side of the ceiling wall  12   u  and the bottom wall  12   d  and at positions extending from the engagement pieces  16  and holding pieces  17  for inserting insertion portions  72  of the fixed terminals  71  to prevent rattle. 
   Furthermore, the box portion  12  is provided with a guide lever attachment portion  20  for attaching a guide lever  61 . The guide lever attachment portion  20  includes an insertion hole  21  provided on the left side surface wall  121  for inserting the guide lever  61 ; depressions  22 A and  22 B communicating with the insertion hole  21  for rotatably supporting an axial portion  62  of the guide lever  61  provided away from the front surface wall  12   f  on the first cam projecting bar  14 A and the second cam bar  14 B at a side of the left side surface wall  121 ; and an elastic pressing piece  23  for pressing the axial portion  62  of the guide lever  61  against the depressions  22 A and  22 B. 
     FIG. 8  is a plan view of a movable member composing the latch device according to the embodiment of the present invention.  FIG. 9  is a front view of the movable member shown in  FIG. 8 ,  FIG. 10  is a right side view of the movable member shown in  FIG. 8 ,  FIG. 11  is a left side view of the movable member shown in  FIG. 8 ,  FIG. 12  is a bottom plan view of the movable member shown in  FIG. 8 , and  FIG. 13  is a cross sectional view taken along line  13 — 13  in  FIG. 11 . 
   As shown in  FIGS. 8 to 11 , a movable member  31  is formed of a synthetic resin, and includes a main member  32  to be inserted into the housing  11 ; and supporting or engaging pieces  44  with hinge portions  45  formed at ends of the front surface and the back surface of the main member  32  for supporting and releasing a striker S (described later). 
   The main member  32  includes a front wall  33  at a right end thereof having a rectangular shape in a side view and the supporting pieces  44 ; an engagement projection  34  formed on an upper side of a back surface of the front wall  33  and having an upper surface inclined downwardly to the left and an inclined back surface (cam surface) with a notched left corner corresponding to the guide long hole  15  of the housing  11 ; a square pole (columnar portion)  35  formed on a half of the back surface of the front wall  33 , extending toward a left side and having steps relative to top and bottom of the front wall  33 ; and a flat plate (plate portion)  40  formed on a half of the front surface of the front wall  33  at the middle of the square pole  35  in a height direction and extending horizontally toward a left side of the front wall  33  and the square pole  35 . 
   A circular hole  36  is formed on a left end surface of the square pole  35  for housing a coil spring  51  extending toward a right side. A housing step portion  37  is formed on a back surface of the square pole  35  connected to the front wall  33  for holding a connecting piece  83  of a movable terminal  81  (described later). Engagement holes  38  passing through vertically are formed in a front surface of the square pole  35  at a right end corresponding to the housing step portions  37  for engaging engagement projections  84   a  of the movable terminal  81 . Protection and guide projections  39  extending to a height same as the front wall  33  are formed on a left end of the square pole  35  at top and bottom corners near the back surface. 
   A first heart cam  41  including a first cam depression  41   a  and a first cam projection  42  for guiding a first trace portion  63   a  (described later) of the guide lever  61  is formed on an upper surface of the flat plate  40 . A second heart cam  43  including a second cam depression  43   a  is formed on a lower surface of the flat plate  40 . The inclined plane (cam surface) of the engagement projection  34 , the first cam projecting bar  14 A, the second cam projecting bar  14 B, the first heart cam  41 , the first cam projection  42 , and the second heart cam  43  are arranged to generate a torsional force or a bending force on the axial portion  62  of the guide lever  6  when a distance between a first trace portion  63   a  and a second trace portion  64   a  is changed. The torsional force or the bending force generates a restoring force on the first trace portion  63   a  or the second trace portion  64   a  in a circulation direction. 
   The lock mechanism is composed of the inclined surface (cam surface) of the engagement projection  34 ; the first cam projecting bar  14 A; the second cam projecting bar  14 B; the first heart cam  41 ; the first cam projection  42 ; the second heart cam  43  (coil spring  51 ); and the guide lever  61 . 
     FIG. 14  is a plan view of a guide lever composing the latch device according to the embodiment of the present invention, and  FIG. 15  is a front view of the guide lever shown in  FIG. 14 . As shown in  FIGS. 14 and 15 , the guide lever  61  is a metal bar folded in a U shape viewed from a front so that the axial portion  62  extending vertically has a first arm  63  and a second arm  64  horizontally extending in parallel at upper and lower sides thereof. Open ends of the first arm  63  and the second arm  64  are folded inwardly to form a space therebetween where the flat plate  40  of the movable member  31  can be inserted, and the first trace portion  63   a  and the second trace portion  64   a  are formed at the ends of the first arm  63  and the second arm  64  so that the guide lever  61  is integrally formed to have a C-shape. 
     FIG. 16  is a plan view of the fixed terminal composing the latch device according to the embodiment of the present invention, and  FIG. 17  is a front view of the fixed terminal shown in  FIG. 16 . As shown in  FIGS. 16 and 17 , a fixed terminal  71  composing a switch is formed of a conductive metallic flat plate, and includes a rectangular insertion portion  72  inserted into the housing  11 , and a connecting portion  73  connected to the insertion portion  72  on a same plane and to be located at an outside of the housing  11 . The insertion portion  72  is provided with a rectangular engagement hole  72   a  as an engagement portion for engaging the engagement projection  16   a  of the housing  11 . The connecting portion  73  is provided with a through hole  73   a  for passing through a conducting wire to be connected. 
     FIG. 18  is a plan view of a movable terminal composing the latch device according to the embodiment of the present invention,  FIG. 19  is a front view of the movable terminal shown in  FIG. 18 , and  FIG. 20  is a right side view of the movable terminal shown in  FIG. 18 . 
   As shown in  FIGS. 18 to 20 , a movable terminal  81  composing the switch is formed of a conductive metallic flat plate, and includes an attachment portion  82  having a U-shape viewed from the right side (direction that the movable member  31  is pushed in); and movable contact pieces  85  corresponding to the holding pieces  17  of the housing  11  and extending from supporting pieces  84  of the attachment portion  82  in the direction that the movable member  31  is pushed in. The attachment portion  82  includes a connecting piece  83  extending vertically, and the supporting pieces  84  extend from the connecting piece  83  in the same direction in parallel and connected to the movable pieces  85 . Each of the supporting pieces  84  is provided with an engagement projection  84   a  for engaging the engagement hole  38  of the movable member  31 . A pair of the movable contact pieces  85  has an interval in which the holding pieces  17  of the housing  11  can reciprocate. 
     FIGS. 21 to 25  are views for explaining an operation of the latch according to the embodiment of the present invention. In  FIGS. 21 to 25 , reference numeral  51  denotes a coil spring as the urging member for urging the movable member  31  in a direction that the movable member  31  projects from the housing  11 . A striker S is provided on an opening-closing member such as a door. 
   A process of assembly will be explained next. First, the connecting piece  83  of the movable terminal  81  is disposed to correspond to the housing step portions  37  of the movable member  31 . The square pole  35  is pushed between the supporting pieces  84  in a state where each of the supporting pieces  84  is pointed at the square pole  35 . As a result, each of the engagement projections  84   a  moves on the square pole  35 , so that the square pole  35  is inserted between the supporting pieces  84 . 
   When the connecting piece  83  is housed in the housing step portions  37 , the engagement projections  84   a  face the engagement holes  38 , so that the supporting pieces  84  return to the original state by the elasticity of the connecting piece  83  and the supporting pieces  84 . Accordingly, each of the engagement projections  84   a  enters each of the engagement holes  38  to engage an edge of the engagement hole  38 , so that the movable terminals  81  are integrally attached to the movable member  31 , as shown in  FIG. 21 . 
   When the movable terminals  81  are attached to the movable member  31 , the front wall  33  and the housing step portions  37  restrict the movable terminals  81  not to move in the left-to-right direction. Outer surface of the connecting piece  83  becomes flush with the surfaces of the front wall  33  and the square pole  35 . Each of the movable contact pieces  85  is inclined such that the movable contact pieces  85  are located away from the square pole  35  as the movable contact pieces  85  are located away from the front wall  33 . 
   Next, one end of the coil spring  51  is inserted into the circular hole  36  of the movable member  31 , and the other end of the coil spring  51  is disposed to correspond to the spring receiver  18  of the housing  11 . While the engagement projection  34  of the movable member  31  is disposed to correspond to the guide long hole  15  and the guide groove  15   a  of the housing  11 , the movable member  31  is inserted into the housing  11  from the protection and guide projections  39 . As a result, each of the movable contact pieces  85  is bent toward the square pole  35  as an edge thereof is pushed by the inner surface of the box portion  12 . Also, the engagement projection  34  pushes up the frame portion  24  with the inclined surface thereof, so that the main member  32  is inserted into the housing  11 . 
   When the engagement projection  34  moves over the frame portion  24  and faces the guide long hole  15 , the frame portion  24  returns to the original state by its own elasticity. Accordingly, the movable member  31  is urged with the coil spring  51  to project from the housing  11 . As a result, the engagement projection  34  engages an edge of the guide long hole  15  (frame portion  24 ), so that the movable member  31  is attached to the housing  11 , as shown in  FIG. 21 . 
   When the movable member  31  is attached to the housing  11  as shown in  FIG. 21 , the spring receiver  18  enters and supports the coil spring  51  so that the coil spring  51  does not buckle during expansion and contraction. As shown in  FIG. 21 , the flat plate  40  of the movable member  31  enters between the first cam projecting bar  14 A and the second cam projecting bar  14 B, so that the flat plate  40  is supported at the top and bottom thereof. 
   Next, the first trace portion  63   a  and the second trace portion  64   a  of the guide lever  61  are pointed to the left side surface wall  121  of the housing  11 . The first trace portion  63   a  is up and the second trace portion  64   a  is down so that the guide lever  61  sandwiches the flat plate  40  of the movable member  31 . In this state, when the guide lever  61  is inserted into the insertion hole  21  of the housing  11  from the first trace portion  63   a  and the second trace portion  64   a , the axial portion  62  pushes and stretches the elastic pressing piece  23 , so that the axial portion  62  is inserted into the depressions  22 A and  22 B. 
   When the axial portion  62  is inserted into the depressions  22 A and  22 B, the elastic pressing piece  23  returns to an original state by its elasticity as shown in  FIG. 21 . The elastic pressing piece  23  presses the axial portion  62  between the depressions  22 A and  22 B toward the first cam projecting bar  14 A and the second cam projecting bar  14 B. Accordingly, the guide lever  61  is attached without coming out and is rotatable inside the depressions  22 A and  22 B. 
   Next, the insertion portions  72  of the fixed terminals  71  are pointed to the left side surface wall  121  of the housing  11 , and the insertion portions  72  are inserted into the insertion holes  19  of the housing  11 . As a result, the insertion portions  72  push the engagement projections  16   a  of the engagement pieces  16 , so that the engagement pieces  16  bend outside and the insertion portions  72  are inserted into the insertion hole  19 . 
   When the insertion portions  72  are inserted into the insertion holes  19 , the edges of the insertion portions  72  are held by the holding pieces  17  not to move upwardly. Accordingly, the engagement projections  16   a  face the engagement holes  72   a , so that the engagement pieces  16  return to an original state by their elasticity. As a result, the engagement projections  16   a  enter the engagement holes  72   a  and engage edges of the engagement holes  72   a  (insertion portion  72 ), so that the fixed terminals  71  are attached without being slipped out of the housing  11 . 
   A process of attaching the latch will be explained next. First, the left side surface wall  121  of the box portion  12  is disposed to correspond to an attached member, for example, an attachment hole of a bracket provided in a main body of a radio cassette corresponding to a rotational end of a door of the radio cassette. The latch device is inserted into the attachment hole from the left side surface wall  121  and pushed in. Accordingly, each of the elastic supporting pieces  13  is pushed by the edge of the attachment hole and bends inside, so that the box portion  12  is inserted into the attachment hole. When the frame portion  24  abuts against a surface of the bracket, each of the elastic supporting pieces  13  projects to the backside of the bracket and returns to the original state by its elasticity, so that each of the elastic supporting pieces  13  engages an edge of the attachment hole at the backside of the bracket. As a result, the latch device is attached to the bracket in the state where the elastic supporting pieces  13  and the frame portion  24  sandwich the bracket. 
   An operation of the latch will be explained next. First, in the assembled state shown in  FIG. 21 , the movable contact pieces  85  of the movable terminals  81  are located away from the corresponding insertion portions  72  of the fixed terminals  71  as shown in  FIG. 22 , so that the switch is in an off-state. In this state, when the front wall  33  of the movable member  31  is pushed by the striker S and pushed into the housing  11  against the force of the coil spring  51 , each of the supporting pieces  44  is pushed by the frame portion  24  and bends inside at the hinge portion  45 , so that the supporting pieces  44  sandwich the striker S not to slip out as shown in  FIG. 23 . 
   When the movable member  31  is pushed into the housing  11 , each of the trace portions  63   a  and  64   a  of the guide lever  61  moves while tracing a lower portion of each of the heart cams  41  and  43  shown in  FIG. 21 . As a result, as shown in  FIG. 23 , the movable member  31  is pushed to the deepest portion of the housing  11 . In this state, when the force that the movable member  31  is pushed into the housing  11  with the striker S is released, the movable member  31  is urged by the coil spring  51  in the direction that the movable member  31  projects from the housing  11 . 
   Accordingly, the second trace portion  64   a  is guided by the cam surface of the edge of the second heart cam  43  to generate the restoration force. As shown in  FIG. 24 , each of the trace portions  63   a  and  64   a  faces and engages each of the cam depressions  41   a  and  43   a , so that the lock mechanism becomes a locked state and the movable member  31  is locked at the push-in position. When the movable member  31  is pushed into the housing  11  until the state shown in  FIG. 24 , the movable contact pieces  85  of the movable terminals  81  contact the corresponding insertion portions  72  of the fixed terminals  71  as shown in  FIG. 25 , so that the switch turns to the on-state. 
   In the state where the lock mechanism is in the locked state, when the movable member  31  is pushed again into the housing  11  against the force of the coil spring  51  through the striker S, each of the trace portions  63   a  and  64   a  is guided by the inclined surface (cam surface) of the engagement projection  34  as indicated by phantom line in  FIG. 23 , so that the lock mechanism turns to the unlock state. Accordingly, in the unlock state, when the force that the movable member  31  is pushed into the housing  11  through the striker S is released, the movable member  31  is urged by the coil spring  51  in the direction that the movable member  31  projects from the housing  11 , so that the movable member  31  returns to the projecting position as shown in  FIG. 21 . When the movable member  31  returns to the state shown in  FIG. 21 , the movable contact pieces  85  of the movable terminal  81  are away from the corresponding insertion portions  72  of the fixed terminals  71  as shown in  FIG. 22 , so that the switch turn to the off-state. 
   As described above, according to the embodiment of the present invention, the lock mechanism is provided on the two sides of the movable member  31  and the portions of the housing  11  corresponding to the two sides of the movable member  31 , so that the locking strength is improved and the locking forces of the two sides is balanced. The switch is also provided on the two sides of the movable member  31  and the portions of the housing  31  corresponding to the two sides of the movable member  31 . Therefore, the movable contact pieces  85  of the movable terminal  81  abut elastically against the inner surface of the housing  11  or the fixed terminal  71 , so that the movable member  31  is reliably operated without inclining. 
   Further, the movable contact pieces  85  of the movable terminal  81  extend in the push-in direction of the movable member  31  and are provided on the lock mechanism side by side. Also, the movable terminal  81  composing the switch provided on the two sides of the movable member  31  is electrically connected. Accordingly, it is possible to reduce a width of the movable member  31  and a width of the latch. Also, the movable terminal  81  provided on the two sides of the movable member  31  is formed in a U-shape seen from the push-in direction of the movable member  31 . Therefore, the movable terminal  81  can be attached to the movable member  31  by fitting the U-shaped part (attachment portion  82 ) into the movable member  31 , thereby improving the operation for attaching the movable terminal  81  to the movable member  31 . 
   When the attachment portions  72  of the fixed terminals  71  are inserted into the insertion holes  19  in the left side surface wall  121 , the engagement projections  16   a  of the engagement pieces  16  engage the engagement holes  72   a  of the attachment portions  72 , so that the fixed terminals  71  are attached to the housing  11 . Accordingly, the operation of assembling the fixed terminals  71  is excellent, and it is possible to assemble by an automatic machine. Also, the fixed terminals  71  can be attached without slipping out. 
   Further, the holding pieces  17  hold the ends of the attachment portions  72  not to part from the inner surface of the housing  11 . Therefore, the movable contact pieces  85  of the movable terminals  81  do not bend to be damaged. 
   In the embodiment described above, the movable terminal  81  is provided on the two sides of the movable member  31 . Alternatively, the movable terminal may be provided only on the front surface or the back surface of the movable member  31 , or a surface other than the front and back surfaces of the movable member  31 . When the movable terminal is provided only on the front or the back surface of the movable member  31 , or the surface other than the front and back surfaces of the movable member  31 , the attachment portion may be formed in the U-shape shown in the embodiment, or the flat plate attachment portion may be inserted between the engagement pieces provided on the movable member. 
   Further, in the embodiment, the movable terminal  81  is provided on the two sides of the movable member  31  and is electrically conducted to be the switch for a single circuit. Alternatively, the movable terminal on the two sides may not be electrically connected with each other so that the movable terminal can serve as switches for two circuits. Moreover, the latch device is applied to the radio cassette, and the invention can be applied to other equipment. 
   As explained above, according to the present invention, the lock mechanism is provided on the two sides of the movable member and the portions of the housing corresponding to the two sides of the movable member. Therefore, the locking strength is improved, and the locking forces of the two sides are balanced. The switch is provided on the two sides of the movable member and the portions of the housing corresponding to the two sides of the movable member. Therefore, the movable contact pieces of the movable terminals elastically contact the inner surface of the housing, the fixed terminal, or the movable member, so that the movable member reliably operates without inclining. 
   Moreover, the terminals composing the switch are provided on the two sides of the movable member and are electrically connected. Therefore, it is possible to reduce the width of the movable member and the width of the latch. The terminals are provided on the two sides of the movable member and are formed in the U-shape seen from the push-in direction of the movable member. Therefore, the U-shaped parts (attachment portions) are fitted into the movable member, so that the terminal can be attached to the movable member, thereby improving the operation of attaching the movable terminal to the movable member. 
   While the invention has been explained with reference to the specific embodiments of the invention, the explanation is illustrative and the invention is limited only by the appended claims.