Patent Publication Number: US-6710275-B2

Title: Push button structure

Description:
The present disclosure relates to the subject matter contained in Japanese Patent Application No. 2002-161117 filed Jun. 3, 2002, which is incorporated herein by reference in its entirety. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a push button structure having a plurality of push buttons which are disposed in an operation panel to be adjacent to each other, and which are depressed in the thickness direction of the operation panel. 
     2. Description of the Related Art 
     Conventionally, as shown in FIG. 8, a plurality of operational push buttons  52  are adjacently juxtaposed on an operation panel  51  of an electrical apparatus such as a car stereo  50 . FIG. 9 shows main portions of the appearance of the push buttons  52 . 
     FIG. 10 shows a section taken along X—X in FIG.  9 . As shown in FIG. 10, each of the push buttons  52  has a key top  53  which has an inverted U-shape, and which protrudes from the operation panel  51  in the upward direction (in FIG. 8, the forward direction). A fulcrum  54  is disposed in front of the key top  53 , and a press portion  55  is disposed in rear of the key top  53 . 
     As shown in FIG. 11, in order to facilitate drawing of molds after a process of molding the push button  52 , the key top  53  of an inverted U-shape is tapered so as to spread as advancing from a top face  57  to a seat portion  58 . 
     FIG. 12A shows the push button  52  which is not depressed, and FIG. 12B shows the push button  52  which is depressed. As shown in FIG. 12B, when the top face  57  of the key top  53  is pushed in the thickness direction (the lateral direction in FIG.  12 B), the push button  52  swings in the lateral direction in FIG. 12B about the fulcrum  54 . 
     As a result, the press portion  55  which is disposed at the rear of the key top  53  pushes a switch  56  to perform an input operation. 
     An electrical apparatus such as the car stereo  50 , which requires a limited installation space, must be miniaturized. 
     In order to realize miniaturization, the operation panel  51  must be reduced in size. However, the size of the plurality of push buttons  52  which are arranged on the operation panel  51  cannot be reduced beyond a certain limit because the area of the top face  57  must be ensured from a viewpoint of operability. 
     Therefore, it has been necessary to reduce the lateral gap between the push buttons  52 . FIG. 13 is a sectional view taken along XIII—XIII in FIG.  9 . 
     As shown in FIG. 13, a side face  59  of the key top  53  on the side of an adjacent push button is inclined so as to spread as advancing from the top face  57  to the seat portion  58 . When the lateral gap a between the push buttons  52  is reduced, therefore, the seat portions  58  interfere with each other, thereby causing a problem in that the operability is impaired. 
     It may be contemplated that the height b of each push button  52  shown in FIG. 13 is reduced to suppress the spreading amount of the side faces of the key top  53 , so that the distance between the adjacent push buttons  52  is shortened. In this case, however, there is a problem in that it is difficult to ensure a sufficient stroke in the push buttons  52 . 
     SUMMARY OF THE INVENTION 
     The invention has been devised in view of the above problems. It is an object of the invention to provide a push button structure in which a gap between push buttons can be reduced without lowering the operability of the push buttons, so that the structure can be made compact. 
     In order to attain the object, a first aspect of the invention provides a push button structure having: a plurality of push buttons which are disposed in an operation panel to be adjacent to each other and which are to be depressed in a thickness direction of the operation panel, wherein each of the push buttons comprises a key top having a plurality of side walls, a top face and a seat portion, and among the side walls of the key top, a portion of a side wall on a side of an adjacent push button is formed not to approach the adjacent push button, the portion extending from a position between the top face and the seat portion toward the seat portion. 
     Push buttons to which the invention can be applied include those which are to be depressed in the thickness direction, and in each of which, for manufacturing reasons, the key top has a sectional shape that spreads as advancing from a top face functioning as a press face to a seat portion. Therefore, the gap between adjacent push buttons is usually limited by the size of the seat portion. In the specification, the term “adjacent” means adjacency in the lateral direction of the operation panel, and does not mean adjacency in the vertical direction of the operation panel. 
     In the thus configured push button structure, the outer face of the side wall of the key top which extends from the side of the top face to that of the seat portion is tapered in a spreading direction in a portion starting from the top face and terminating at the position between the top face and the seat portion. By contrast, the portion of the outer face starting from that position and terminating in the seat portion is not tapered in a spreading direction so as not to approach an outer face of the adjacent key top. 
     Consequently, the gap between adjacent push buttons is limited by the size of the key top at the position between the top face and the seat portion, so that each push button can further approach the adjacent push button as compared with the conventional case where the gap is determined by the size of the seat portion. As a result, the push button structure can be made compact. 
     According to a second aspect of the invention, an outer face in the portion extending from the position between the top face and the seat portion toward the seat portion is inclined to a side which is opposite to the adjacent push button, as advancing toward the seat portion. 
     In the outer face of the key top of the push button, the portion beyond the position between the top face and the seat portion is formed so as not to approach the outer face of the adjacent key top. From a manufacturing viewpoint, the inner face of the key top is preferably tapered so as to spread as advancing from the rear face of the top face to the seat portion. 
     In the thus configured push button structure, the gap between the push button and the adjacent one is increased in a portion of the outer face of the key top beyond the position between the top face and the seat portion. Therefore, the push buttons can further approach each other, and the push button structure can be made compact. 
     According to a third aspect of the invention, a step which is bent toward a center of the key top is disposed at the position between the top face and the seat portion of the outer face, thereby placing a starting end of the outer face extending from the position between the top face and the seat portion toward the seat portion, to be closer to the center of the key top than a terminating end of the outer face extending from the top face to the position between the top face and the seat portion. 
     In the thus configured push button structure, the position of the starting end of the outer face extending from the position between the top face and the seat portion toward the seat portion is shifted toward the center from the position of the terminating end of the outer face extending from the top face of the key top to the position between the top face and the seat portion. In a process of manufacturing the push button, therefore, the terminating and starting positions are not required to coincide with each other, so that the manufacturing process can be simplified. 
     Since the outer face portion of the key top extending from the position between the top face and the seat portion toward the seat portion is closer to the center, the adjacent push buttons can be placed closer to each other, with the result that the push button structure can be made compact. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing an embodiment of the push button structure of the invention; 
     FIG. 2 is a sectional view of a push button taken along II—II in FIG. 1; 
     FIG. 3 is an enlarged view of a step portion; 
     FIG. 4 is an overall view of an operation panel using a push button structure which is the embodiment of the invention; 
     FIG. 5 is a diagram illustrating another embodiment; 
     FIG. 6 is a diagram illustrating a further embodiment; 
     FIG. 7 is a sectional view showing a fitted state of molds in a process of molding a push button; 
     FIG. 8 is a perspective view showing a car stereo that is a conventional example in which a push button structure is used; 
     FIG. 9 is an external view of a push button; 
     FIG. 10 is a sectional view taken along X—X in FIG. 9; 
     FIG. 11 is a sectional view showing a fitted state of molds in a process of molding a push button; 
     FIG. 12A is a sectional view showing a push button which is not depressed, and FIG. 12B is a sectional view showing the push button which is depressed; and 
     FIG. 13 is a sectional view taken along XIII—XIII in FIG.  9 . 
    
    
     DETAILED DESCRIPTION OF THE PREFFERED EMBODIMENTS 
     Hereinafter, embodiments of the push button structure of the invention will be described in detail with reference to the accompanying drawings. In the following description of the embodiments, the components which have been described with reference to FIGS. 8 to  13  are denoted by the same reference numerals in the figures, and their description is simplified or omitted. 
     As shown in FIG. 4, a push button structure  10  which is an embodiment of the invention is disposed inside the operation panel  51 . Push buttons  11  are swingably attached to support members  12   a  and  12   b  so that adjacent push buttons  11  are attached to different support members. In the embodiment, the push buttons are classified into two groups. The term “adjacent” means adjacency in the lateral direction in FIG. 4, and, even in the case where the push buttons  11  are arranged in a plurality of rows which are vertically juxtaposed, vertical adjacency is ignored. 
     When the push buttons  11  of the two groups are fitted from the rear side into a push button opening  13  of the operation panel  51  so as to protrude to the front, therefore, the plurality of push buttons  11  are arranged with being exposed from the front face of the operation panel  51 . Since the push buttons  11  are supported by the respective support members  12   a  and  12   b  so as to be immovable in the lateral direction in FIG. 4, it is not necessary to dispose a frame between the adjacent push buttons  11 , whereby the gap between the push buttons  11  can be reduced, so that the operation panel  51  can be made compact. 
     FIG. 1 shows the appearance of the push button  11 . FIG. 2 shows a sectional shape of the push button  11  taken along II—II in FIG.  1 . The whole of the push button  11  has an inverted U-shape. In the outer side of the key top  53 , a side wall  15  is disposed which starts from the top face  57  to be depressed by a finger and extends toward the seat portion  58  via a rounded portion  14 . In an outer face  16  of the side wall  15 , an outer face  16   a  which extends to an intermediate position  17  spreads laterally. 
     Referring also to FIG. 3, a step  18  which is bent toward the center of the key top  53  is disposed at the intermediate position  17  in the outer face  16  of the key top  53 , and the terminating end  19  of the outer face  16   a  of the key top  53  which extends from the top face  57  to the intermediate position  17  is positioned in the outer edge of the step  18 . 
     By contrast, in the outer face  16  of the side wall  15  of the key top  53 , an outer face  16   b  which extends from the intermediate position  17  toward the seat portion  58  is formed into a shape which does not spread at least toward the outer side, thereby preventing the side wall from approaching the adjacent push button  11 . 
     Specifically, the starting end  20  of the outer face  16   b  which extends from the intermediate position  17  toward the seat portion  58  is positioned in the inner edge of the step  18 . Preferably, the outer face is tapered so as to be inclined to the inner side of the key top  53  as advancing from the starting end  20  toward the seat portion  58 . Alternatively, as in a push button  21  shown in FIG. 5, the outer face  16   b  may extend straight downward from the starting end  20  toward the seat portion  58 . 
     As shown in FIG. 2, the inner face  22  of the push button  11  is tapered so as to uniformly spread as advancing from the inside of the top face  57  to the seat portion  58 . 
     In the above-described push button structure  10 , the outer face  16   a  of the side wall  15  of the key top  53  which extends from the top face  57  toward the seat portion  58  is tapered in a spreading direction in the portion starting from the top face  57  and terminating at the intermediate position  17 . 
     By contrast, the outer face  16   b  which extends from the intermediate position  17  to the seat portion  58  is formed so as not to approach the outer face  16   b  of the adjacent key top  53 . Therefore, the gap between the adjacent push buttons  11  is determined by the size of the key top  53  at the intermediate position  17 , so that the push button can further approach the adjacent push button  11  as compared with the conventional case where the gap is determined by the size of the seat portion  58 . As a result, the push button structure  10  can be made compact. 
     As shown in FIG. 7, the fitting position of molds in the process of manufacturing the push button  11  can be set to coincide with the position of the step  18 . Therefore, the push button  11  of a desired sectional shape can be manufactured even when some manufacturing error occurs. The step  18  is required only to be directed toward the inside of the key top  53 , and the length of the step  18  is not particularly restricted. 
     The push button structure  10  of the invention is not limited to the above-described embodiments, and may be adequately modified or improved. 
     In the above-described embodiments, the intermediate position  17  of the outer face of the side wall  15  of the key top  53  is placed in the vicinity of the middle in the height direction. Alternatively, as a push button  23  shown in FIG. 6, the intermediate position  17  may be placed in succession to the rounded portion  14  continuous to the top face  57 . In this case, the outer face  16  of the key top  53  is tapered toward the inside of the key top  53  with starting from the rounded portion  14 . 
     As described above, in the push button structure of the invention, the outer face of the side wall of the key top which extends from the side of the top face to that of the seat portion is tapered in a spreading direction in a portion starting from the top face and terminating at the intermediate position. By contrast, the portion of the outer face which starts from the intermediate position and terminates in the seat portion is not tapered in a spreading direction so as not to approach the outer face of the adjacent key top. Therefore, the gap between adjacent push buttons is limited by the size of the key top at the intermediate position, so that each push button can further approach the adjacent push button as compared with the conventional case where the gap is determined by the size of the seat portion. As a result, the push button structure can be made compact.