Patent Publication Number: US-9842710-B2

Title: Key switch device and keyboard

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2014-197484 filed on Sep. 26, 2014, the entire contents of which are incorporated herein by reference. 
     FIELD 
     A certain aspect of the embodiments is related to a key switch device and a keyboard. 
     BACKGROUND 
     Conventionally, there is known a key switch device having a gear link structure in which a pair of link members is assembled to be interlocked by meshing their ends with each other (for example, see Japanese Patent Laid-Open No. 2009-76321). 
     A key switch device includes a key top, the pair of the link members interlocked with each other to move the key top vertically upward and downward, a support plate, and a frame member for attaching one ends of the link members to the support plate. The frame member is formed with bearing portions into which pivot shaft portions provided in the pair of the link members are fitted respectively. Also, the frame member has leg portions extending vertically downward. The support plate has circular-shaped through holes through which the leg portions of the frame member respectively penetrate. 
     The bearing portions of the frame member respectively receive the pivot shaft portions of the link members, and the leg portions of the frame member respectively penetrate through the through holes of the support plate, whereby the pair of the link members is pivotally attached on the support plate. Ends of the leg portions of the frame member respectively penetrating through the through holes of the support plate are deformed by thermal caulking, which fixes the frame member on the support plate. 
     SUMMARY 
     According to an aspect of the present invention, there is provided a key switch device that includes: a key top that includes an operating surface; a pair of link members that is interlocked with each other to move the key top upward and downward; a frame member that includes a leg portion extending downward and a flange portion provided at an end of the leg portion, and pivotably supports the pair of the link members; and a support plate that includes a through hole through which the leg portion and the flange portion penetrate, and a projection portion projecting upwardly from a part of an outer periphery of the through hole toward an inside of the through hole. 
     The objects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the claims. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not restrictive of the invention, as claimed. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a structural view of a key switch device according to the present embodiment; 
         FIG. 2  is a sectional view of the key switch device take along A-A line of  FIG. 1 ; 
         FIG. 3  is a structural view of a keyboard; 
         FIG. 4  is a structural view of a frame member; 
         FIG. 5  is a structural view of a link member; 
         FIG. 6  is a view illustrating a positional relationship between the frame member and a pair of the link members; 
         FIG. 7  is a sectional view of a membrane sheet; 
         FIG. 8A  is a view illustrating a shape of an oblong hole viewed from an upper side,  FIG. 8B  is a view illustrating a positional relationship among the oblong hole, a leg portion, and a flange portion,  FIG. 8C  is a sectional view taken along line B-B of  FIG. 8B ,  FIG. 8D  is a view illustrating the positional relation among the oblong hole, the leg portion, and the flange portion, and  FIG. 8E  is a sectional view taken along line C-C of  FIG. 8D ; 
         FIGS. 9A and 9B  are sectional views of the frame member, the membrane sheet, and the support plate taken along line D-D of  FIG. 1 ; 
         FIGS. 10A through 10D  are views illustrating variations of the arrangement of the four oblong holes; 
         FIG. 11A  is a structural view of the first variation of the frame member, and  FIG. 11B  is a structural view of the second variation of the frame member; and 
         FIG. 12A  is a sectional view of the frame member illustrated in  FIG. 11A  before thermal caulking, and  FIG. 12B  is a sectional view the frame member illustrated in  FIG. 11A  after thermal caulking. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     Incidentally, when the link member deforms, the link member is detached from the bearing portion of the frame member, or defective contact of the membrane sheet occurs, that is, in a case of a defect in the key switch device, the key switch device needs to be disassembled and repaired. 
     Since the frame member is, however, fixed on the support plate by thermal caulking, it is not easy to detach the link members and the frame member from the support plate, and it is difficult to disassemble and repair the key switch device. 
     The following will describe embodiments according to the present invention with reference to drawings. 
       FIG. 1  is a structural view of a key switch device  100  according to the present embodiment.  FIG. 2  is a sectional view of the key switch device  100  taken along line A-A of  FIG. 1 .  FIG. 3  is a structural view of a keyboard  50 . 
     The key switch device  100  illustrated in  FIG. 1  includes a key top  102  having an operating surface  102   a  which an operator pushes down, a pair of link members  103  supporting the key top  102  and interlocked with each other so as to move the key top  102  vertically upward and downward, and a frame member  106  for fixedly attaching ends of the link members  103  on a support plate  105  having a flat plate shape. A membrane sheet  104  including contacts (not illustrated) functioning as a switch is provided on the support plate  105 . As illustrated in  FIG. 2 , a back surface of the key top  102  is formed with guide portions  102   b  for slidably guiding slide portions  103   d  of the link members  103  described later. 
     Plural key switch devices  100  illustrated in  FIG. 1  are arranged in the keyboard  50  illustrated in  FIG. 3 . A membrane sheet  104 ′ and a support plate  105 ′ each having a large size in common with all key switch devices  100  are included in the keyboard  50 . The key top  102 , the link members  103 , and the frame member  106  are provided for every key switch device  100 . 
       FIG. 4  is a structural view of the frame member  106 . As illustrated in  FIG. 4 , the frame member  106  is a frame-shaped member made of a resin and having a substantially rectangular shape in plan view. A frame portion  106   a  is formed with bearing portions  106   b  into which pivot shaft portions  103   c  of the link members  103  described below are pivotably fitted respectively. Further, the frame member  106  includes leg portions  106   c  extending vertically downward and respectively inserted into oblong holes  105   a  of the support plate  105 , flange portions  106   d  respectively provided horizontally in the ends of the leg portions  106   c  and each having a disk shape, and a through hole  106   e  through which an opening end  104   a  of the membrane sheet  104  and a dome rubber  104   b  penetrate when the frame member  106  is attached to the support plate  105 . When the leg portions  106   c  and the flange portions  106   d  are respectively inserted into the oblong holes  105   a  of the support plate  105 , a bottom portion of the frame member  106  (that is, the bottom portion of the frame member  106  other than the leg portions  106   c  and the flange portions  106   d ) comes into contact with an upper surface of the support plate  105 . 
       FIG. 5  is a structural view of the link member  103 . Since each of the link members  103  of this embodiment has the same shape,  FIG. 5  illustrates the single link member  103 . The link members  103  are made of resin, and the ends thereof are meshed with each other to be assembled and interlocked with each other. The link member  103  is a V-shaped gear link in side view when the key top  102  is positioned at an upper limit position of the upward and downward movement. Each link member  103  includes arm portions  103   a  extending in substantially parallel with each other in the same direction, and a body portion  103   b  connecting between the arm portions  103   a.    
     In  FIG. 5 , a peripheral region around distal ends of both arm portions  103   a  spaced away from the body portion  103   b  is defined as a first end region of the link member  103 . Also, a peripheral region around proximal ends of both arms portions  103   a  adjacent to the body portion  103   b  is defined as a second end region of the link member  103 . 
     In the first end region of each link member  103 , inner side surfaces of the arm portion  103   a  facing each other are respectively provided with the pivot shaft portions  103   c  having a projection shape. Also, in the second end region of each link member  103 , outer side surfaces of the arm portion  103   a  facing away from each other are respectively provided with the slide portions  103   d  having a projection shape. Further, one of the arm portions  103   a  is provided with a first teeth portion  103   e  in the first end region, and the other of the arm portions  103   a  is provided with a second teeth portion  103   f  in the first end region. Each link member  103  is located between the membrane sheet  104  and the key top  102 , in a state where the pivot shaft portions  103   c  in the first end region are pivotally fitted into the respective bearing portions  106   b  of the frame member  106  and where the slide portions  103   d  in the second end region are slidably fitted into the respective guide portions  102   b  (see  FIG. 2 ) provided on the back surface of the key top  102 . In this state, the first teeth portion  103   e  of one of the link members  103  is meshed with the second teeth portion  103   f  of the other of the link members  103  to be interlocked with each other. Thus, the pair of the link members  103  is interlocked with each other and respectively pivoted about the pivot shaft portions  103   c.    
       FIG. 6  is a view illustrating a positional relationship between the frame member  106  and the link member  103 . When the key top  102  is located at a lower limit position of the upward and downward movement, the frame member  106  is located inside the link members  103 . Since the pivot shaft portions  103   c  of each link member  103  are pivotally fitted into the respective bearing portions  106   b  of the frame member  106 , even when the frame member  106  and the link member  103  slide in the X direction and the Y direction of  FIG. 6  (that is, in the horizontal direction), each link member  103  is not detached from the frame member  106 . 
     Returning to  FIG. 1 , the membrane sheet  104  is made of a transparent material. The membrane sheet  104  includes through holes  104   j  for fixing the frame member  106  and the link member  103  to the support plate  105 , and the opening end  104   a . The opening end  104   a  is attached with the dome rubber  104   b  that generates the reaction force against the force pushing down the key top  102 . 
       FIG. 7  is a sectional view of the membrane sheet  104 . As illustrated in 
       FIG. 7  is a sectional view of the membrane sheet  104 . As illustrated in  FIG. 7 , the membrane sheet  104  includes two substrates  104   c  and  104   d  and a pair of contacts  104   e  corresponding to one of the key switches functioning as a switch. The substrates  104   c  and  104   d  are respectively provided with the contacts  104   e , and these contacts  104   e  form a pair. The contacts  104   e  of the substrates  104   c  and  104   d  come into contact with each other, so that the contacts  104   e  are brought into an on-state. The substrates  104   c  and  104   d  are spaced away from each other by a predetermined distance, and a spacer  104   h  is provided therebetween. In order for the contacts  104   e  to face each other, they are formed on the respective substrates  104   c  and  104   d  at the position of an aperture  104   i  provided in the spacer  104   h . A projection  104   g  is formed in a ceiling portion  104   f  of the dome rubber  104   b . When the key top  102  is pushed down, the dome rubber  104   b  is deformed and buckled, so the projection  104   g  pushes down a portion of the contacts  104   e  formed in the membrane sheet. Thus, the contacts  104   e  come into contact with each other, and a key input is performed. 
     As illustrated in  FIG. 1 , the support plate  105  is formed with four oblong holes  105   a  for respectively inserting the disk-shaped flange portions  106   d  of the frame member  106  and for fixing the frame member  106 . The oblong holes  105   a  are through holes.  FIG. 8A  is a view illustrating the shape of the oblong hole  105   a  when viewed from the upper side.  FIG. 8B  is a view illustrating a positional relation among the oblong hole  105   a , the leg portion  106   c , and the flange portion  106   d ,  FIG. 8C  is a sectional view taken along line B-B of  FIG. 8B .  FIG. 8D  is a view illustrating the positional relation among the oblong hole  105   a , the leg portion  106   c , and the flange portion  106   d ,  FIG. 8E  is a sectional view taken along line C-C of  FIG. 8D . The shape of the flange portion  106   d  is not limited to a disk shape, but may be also n-polygonal shape (n is integer number of three or more). 
     As illustrated in  FIGS. 8A to 8E , the outer peripheral portion of the oblong hole  105   a  is partially provided with a projection portion  105   b  angularly upwardly protruding from the surface of the support plate  105  toward the inside of the oblong hole  105   a . The projection portion  105   b  has a U shape in top view. Also, as illustrated in  FIGS. 8B and 8E , a width Cl between opposite sides of the projection portion  105   b  (that is, a width of the inside of the U shape) is greater than a diameter A 1  of the leg portion  106   c , but is smaller than a diameter B 1  of the disk-shaped flange portion  106   d . Thus, as illustrated in  FIG. 8B , the flange portion  106   d  and the leg portion  106   c  are inserted into the oblong hole  105   a , and the flange portion  106   d  and the leg portion  106   c  are slid in the X direction as illustrated in  FIG. 8D , so that the frame member  106  is fixed to the support plate  105 . In contrast, the frame member  106  can be detached from the support plate  105  by sliding the flange portion  106   d  and the leg portion  106   c  in the minus X direction from the state of  FIG. 8D . Note that the contact relationship between the frame member  106  and the support plate  105  will be described later. 
       FIGS. 9A and 9B  are sectional views of the frame member  106 , the membrane sheet  104 , and the support plate  105  taken along line D-D of  FIG. 1 .  FIG. 9A  indicates a state before the frame member  106  is fixed to the support plate  105 .  FIG. 9B  indicates a state after the frame member  106  is fixed to the support plate  105 . Also, in  FIG. 9A , the frame member  106  is illustrated by a dotted line, except for the leg portions  106   c  and the flange portions  106   d . When the leg portions  106   c  and the flange portions  106   d  are inserted into the respective oblong holes  105   a  of the support plate  105  as illustrated in  FIG. 9A , the bottom portion of the frame member  106 , except for the leg portions  106   c  and the flange portions  106   d , comes into contact with the upper surface of the support plate  105 . Then, when the flame member  106  is slid in the X direction from the state of  FIG. 9 , the flange portions  106   d  are respectively engaged with the projection portions  105   b  as illustrated in  FIG. 9B , and the frame member  106  is fixed to the support plate  105 . In other words, in  FIG. 9B , the frame member  106  is fixed to the support plate  105  so as not to move upward and downward as the bottom portion of the frame member  106  is in contact with the upper surface of the support plate  105  and the flange portions  106   d  are respectively in contact with lower surfaces of the projection portions  105   b.    
       FIG. 10A  is a view illustrating a first variation of the arrangement of the four oblong holes  105   a .  FIGS. 10B ( 1 ) and  10 B( 2 ) are views illustrating states before and after the frame member  106  is fixed to the support plate  105 , respectively, in a case of employing the arrangement of the four oblong holes  105   a  illustrated in  FIG. 10A   FIG. 10C  is a view illustrating a second variation of the arrangement of the four oblong holes  105   a .  FIGS. 10D ( 1 ) and  10 D( 2 ) are views illusrating states before and after the frame member  106  is fixed to the support plate  105 , respectively, in a case of employing the arrangment of the four oblong holes  105   a  illustrated in  FIG. 10C . 
     In  FIG. 1 , the four oblong holes  105   a  are provided in the support plate  105  such that major axes of the four oblong holes  105   a  are parallel with the X direction. As illustrated in  FIG. 10A , however, the four oblong holes  105   a  may be provided in the support plate  105  such that each major axis Z of the four oblong holes  105   a  is tangent to the same periphery  110  passing through each center  105   c  of the oblong holes  105   a . That is, the four oblong holes  105   a  may be provided in the support plate  105  such that the frame member  106  is rotated to be fixed to the support plate  105 . 
     As illustrated in  FIG. 10B ( 1 ), the flange portion  106   d  and the leg portion  106   c  of the frame member  106  are inserted into each oblong hole  105   a  in the state where the frame member  106  is not parallel with the X direction or the Y direction. Moreover, the frame member  106  is fixed to the support plate  105  by rotating the frame member  106  counterclockwise. In the state where the frame member  106  is fixed to the support plate  105 , the frame member  106  is parallel with the X direction or the Y direction. In the state where the frame member  106  is fixed to the support plate  105 , the frame member  106  can be detached from the support plate  105  by rotating the frame member  106  clockwise. In general, an operator does not need to push down the key top  102  so as to rotate the key top  102 , so that the key switch device  100  can avoid being carelessly detached from the keyboard main body. 
     Also, as illustrated in  FIG. 10C , the four oblong holes  105   a  may be provided in the support plate  105  such that major axes of the four oblong holes  105   a  are parallel with the Y direction. In this case, as illustrated in  FIG. 10D ( 1 ), the flange portion  106 d and the leg portion  106 c of the frame member  106  are inserted into each oblong hole  105   a  in the state where the frame member  106  is parallel with the X direction or the Y direction. Further, the frame member  106  is fixed to the support plate  105  by sliding the frame member  106  in the minus Y direction. In the state where the frame member  106  is fixed to the support plate  105 , the frame member  106  can be detached from the support plate  105  by sliding the frame member  106  in the Y direction. 
     In  FIG. 4 , the flange portion  106   d  is provided at the end of the leg portion  106   c  of the frame member  106  beforehand. As illustrated in  FIG. 11A , however, the flange portion  106   d  may not be provided in the end of the leg portion  106   c  of the frame member  106 . In other words, the leg portion may have a stick shape such that the end thereof is thin and extends vertically downward. 
       FIG. 12A  is a sectional view of the frame member  106 , the membrane sheet  104 , and the support plate  105  of  FIG. 11A . Since the end of the leg portion  106   c  of the frame member  106  in  FIG. 11A  is not provided with the flange portion, the frame member  106  cannot be fixed to the support plate  105  in this state. Thus, as illustrated in  FIG. 12B , the end of the leg portion  106   c  penetrating through the oblong hole  105   a  is deformed by thermal caulking, which causes the end of the leg portion  106   c  to be formed with a flange portion  106   f  having a diameter greater than the width Cl of the projection portion  105   b  mentioned above. Thus, the frame member  106  is fixed to the support plate  105 . Also, in the case where the end of the leg portion  106   c  is formed with the flange portion  106   f , the frame member  106  can be detached from the support plate  105  by sliding the frame member  106  in the minus X direction. 
     Also, as illustrated in  FIG. 11B , a thin portion  106   g  may be formed in the vicinity of the end of the leg portion  106   c . It is thus possible to avoid filling the oblong hole  105   a  with a resin melted by thermal caulking. 
     As described above, according to the embodiment, the frame member  106  includes the leg portions  106   c  extending downward, and the flange portions  106   d  respectively provided in the ends of the leg portions  106   c . The support plate  105  includes the oblong holes  105   a  through which the leg portions  106   c  and the flange portions  106   d  of the frame member  106  respectively penetrate, and the projection portions  105   b  respectively protruding angularly upwardly from parts of the outer peripheries of the oblong holes  105   a  to the insides of the oblong holes  105   a . Thus, the leg portions  106   c  and the flange portions  106   d  are respectively inserted into the oblong holes  105   a , and are slid in a predetermined direction (for example, in the X direction), whereby the frame member  106  is fixed to the support plate  105 . In contrast, the leg portions  106   c  and the flange portions  106   d  can be slid in the direction opposite to the predetermined direction (for example, in the minus X direction), whereby the frame member  106  can be detached from the support plate  105 . Accordingly, a repairer can disassemble and repair the key switch device  100  with ease. Also, only a defective key (the key top  102 , the frame member  106 , the link member  103 , or the dome rubber  104   b ) can be replaced, thereby reducing waste matters. Also, a detached key top  102 , a detached frame member  106 , a detached pair of the link members  103 , and a detached dome rubber  104   b  can be reused unless they are broken. Further, in the case where the end of the leg portion  106   c  of the frame member  106  is provided with the flange portion  106   d  beforehand, since a jig for thermal caulking is not needed, the cost of the production facility of the key switch device can be reduced. 
     All examples and conditional language recited herein are intended for pedagogical purposes to aid the reader in understanding the invention and the concepts contributed by the inventor to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions, nor does the organization of such examples in the specification relate to a showing of the superiority and inferiority of the invention. Although the embodiments of the present invention have been described in detail, it should be understood that the various change, substitutions, and alterations could be made hereto without departing from the spirit and scope of the invention.