JP2011040320A - Key switch module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a key switch module capable of reducing metallic squeaking noises caused by a clicking operation and contact noises between a movable contact electrode and a fixed contact electrode by forming a part of the fixed contact electrode and the movable contact electrode as basic structural elements of a key switch or a part of a base board for mounting the key switch with a sound absorption member and attaining thinning of the whole key switch module. <P>SOLUTION: In the key switch module 11 having the key switch provided with the base board 12, a fixed contact 14 formed on the base board 12, and a dome spring 15 for covering the fixed contact 14, the sound absorption member 17 made of anisotropic conductive rubber is arranged so as to cover the fixed contact 14. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a key switch module mounted on a small electronic device such as a mobile phone.

  FIG. 7 shows a part of a cross-sectional structure of a conventional general key switch module 1. The key switch module 1 includes a substrate 2, an electrode pattern (circuit electrode 3, fixed contact electrode 4) formed on the substrate 2, a movable contact electrode 5 disposed above the fixed contact electrode 4, And a sheet material 6 that covers the movable contact electrode 5. The movable contact electrode 5 is formed in a dome shape by a thin metal plate having flexibility, and electrical connection with the fixed contact electrode 4 is achieved by pressing the top with a finger or the like.

  The movable contact electrode 5 is electrically connected to the fixed contact electrode 4 while maintaining the pressure, and the conduction is interrupted by releasing the pressure. By such a pressing operation, a contact sound between the movable contact electrode 5 and the fixed contact electrode 4 or a rebound sound of the movable contact electrode 5 generated when releasing the press is generated.

  A key switch module (dome switch) having a structure in which a buffer member is disposed between the fixed contact electrode 4 and the movable contact electrode 5 in order to reduce the sound generated during such pressing operation is disclosed (Patent Document 1). ).

JP 2004-31113 A

  The dome switch disclosed in Patent Document 1 is generated when the dome-shaped movable contact electrode is recessed when contacting the fixed contact electrode, or when the contact with the fixed contact electrode is released to return to the original state. The main object is to reduce the bending deformation sound of the movable contact electrode itself. In order to realize this, a vibration absorbing member is disposed on the outer peripheral portion of the movable contact electrode.

  The vibration absorbing member is mainly located at the base end of the bending deformation of the movable contact electrode, and is provided only in the vicinity of the outer peripheral portion which is a support portion with the substrate, so that the metallic property emitted from the movable contact electrode The effect of reducing the bending sound is not sufficiently obtained. In the above structure, there is no effect on the sound generated when the movable contact electrode contacts the fixed contact electrode.

  In addition, since the vibration absorbing member is formed separately from the substrate, the fixed contact electrode, and the movable contact electrode, which are basic components of the switch, there is a problem that the manufacturing and product costs increase. Furthermore, since the vibration absorbing member is disposed so as to overlap a part of the substrate and the movable contact electrode, the thickness of the entire key switch module is increased, and the reduction in thickness is restricted.

  Accordingly, an object of the present invention is to form a click by forming a part of a fixed contact electrode or a movable contact electrode, which is a basic component of a key switch, or a part of a substrate on which the key switch is mounted with a sound absorbing member. It is an object to provide a key switch module capable of reducing metallic bending sound accompanying operation and contact sound between a movable contact electrode and a fixed contact electrode and reducing the overall thickness.

  In order to solve the above problems, a key switch module according to the present invention includes a substrate, and a key switch including a fixed contact electrode formed on the substrate and a dome-shaped movable contact electrode covering the fixed contact electrode. In the key switch module, at least an upper surface of the fixed contact electrode is formed of a conductive sound absorbing member.

  According to the key switch module of the present invention, since the upper surface of the fixed contact electrode that contacts the dome-shaped movable contact electrode is formed of the conductive sound absorbing member, the metal at the time of contact is ensured while ensuring conduction at the time of pressing. Can absorb natural contact sound and vibration sound. As a result, it is possible to provide a key switch module with excellent silence.

  The sound absorbing member may be provided as a part of the fixed contact electrode, or the fixed contact electrode itself may be constituted by a sound absorbing member. For this reason, since the thickness of the whole key switch module does not increase, it is possible to reduce the thickness while simultaneously providing quietness.

It is a fragmentary sectional view of the key switch module of a 1st embodiment concerning the present invention. It is a disassembled perspective view of the key switch module comprised using the anisotropic conductive rubber which has a concentric conductive part. It is a disassembled perspective view of the key switch module comprised using anisotropic conductive rubber which has a dot-shaped electroconductive part. FIG. 3 is a partial cross-sectional view of a key switch module in which conductive rubber is arranged separately for fixed contacts and circuit electrodes. It is a fragmentary sectional view of the key switch module of 2nd Embodiment which concerns on this invention. It is a fragmentary sectional view of the key switch module of a 3rd embodiment concerning the present invention. It is a fragmentary sectional view of the conventional key switch module.

  Hereinafter, embodiments of a key switch module according to the present invention will be described in detail with reference to the accompanying drawings. 1 to 3 show a key switch module 11 according to a first embodiment of the present invention. The key switch module 11 includes a substrate 12 and a key switch portion including a fixed contact electrode (fixed contact) 14 provided at a predetermined position on the substrate 12 and a movable contact electrode (dome spring) 15 covering the fixed contact 14. It is a basic component.

  The substrate 12 is made of a thinly molded epoxy resin plate or flexible (FPC) plate, and the fixed contact 14 is formed on the surface, and the circuit electrode 13 serving as a switch circuit is formed around the fixed contact 14 in a pattern. .

  In the present embodiment, a conductive sound absorbing member 17 is disposed on the fixed contact 14 and the circuit electrode 13 formed flat on the upper surface of the substrate 12, and the dome spring 15 is disposed with the sound absorbing member 17 interposed therebetween. A sheet material 16 for fixing the dome spring 15 is covered along the dome spring 15. The sheet material 16 is coated with a transparent adhesive uniformly on the entire back surface, and the dome spring 15 is adhered and held, and after aligning it with the upper surface of the substrate 12 on which the fixed contact 14 is formed, the sheet material 16 is adhered. To cover. In addition, the sheet material 16 can also be made to adhere to the movable contact 14 directly on the back surface, and can be closely formed along the outer shape of the dome spring 15 by means such as heating and pressurization.

  An anisotropic conductive rubber is used for the sound absorbing member 17. The anisotropic conductive rubber includes an insulating base portion 18 and conductive portions 19 distributed on the base portion 18. The conductive portion 19 is formed in a concentric pattern centered on the fixed contact 14 as shown in FIG. 2 or a dot pattern as shown in FIG. The conductive portion 19 having such a pattern is formed in the thickness direction in the base portion 18, and one end is exposed as an electrode on the upper surface and the lower surface.

  The sound absorbing member 17 having the above structure is formed into a sheet shape having a thickness of about 20 to 100 μm, and is in close contact with the fixed contact 14 and the circuit electrode 13 by an adhesive layer provided on the back surface side. The conductive portion 19 is not limited to a concentric circle or dot, but may be a pattern having no continuity such as a broken line or a stripe. The base portion 18 can be formed using a urethane resin having cushioning properties in addition to the rubber material.

  The dome spring 15 is positioned so that its center faces the fixed contact 14, and is fixed by placing an outer peripheral portion on the circuit electrode 13. The dome spring 15 is formed in a dome shape made of a thin metal material in order to obtain an appropriate click feeling. Further, in the case of a key switch module provided with a light source for illumination, an effect of improving illumination efficiency by a light scattering action can be obtained by mirror-finishing the upper surface of the dome spring 15.

  The key switch module 11 having the above structure is bent and deformed downward by pressing the top portion P of the dome spring 15 with a finger or the like, and comes into contact with the upper surface of the sound absorbing member 17. By this contact, conduction between the dome spring 15 and the fixed contact 14 is achieved via the conductive portion 19 in the sound absorbing member 17. Thus, since the sound absorbing member 17 serves as a cushion and conducts, the contact sound during conduction can be greatly reduced and a light touch click feeling can be obtained.

  Further, since the sound absorbing member 17 is formed in a thin sheet shape having a uniform thickness and is simply placed on the upper surface of the substrate 12 on which the fixed contacts 14 and the circuit electrodes 13 are formed, the key switch module is easy to manufacture. The thinning of the entire 11 is not limited. Furthermore, since the stroke width of the dome spring 15 is not reduced, the click feeling is not impaired.

  In the above embodiment, anisotropic conductive rubber is used as the sound absorbing member 17, but conductive rubber having conductivity as a whole can be used. When such conductive rubber is used, it is necessary to prevent the fixed contact 14 and the circuit electrode 13 from conducting. Therefore, as shown in FIG. 4, the conductive rubbers 20a and 20b are arranged separately on the upper surface of the fixed contact 14 and the upper surface of the circuit electrode 13 on which the outer periphery of the dome spring 15 is placed. As described above, even when the conductive rubbers 20a and 20b are disposed on a part of the fixed contact 14 and the circuit electrode 13, the operation sound at the time of clicking can be reduced by the cushioning property of the conductive rubbers 20a and 20b. .

  FIG. 5 shows a cross-sectional structure of the key switch module 21 of the second embodiment. The key switch module 21 of this embodiment has a sound absorbing member 27 disposed on the back side of the substrate 22. The sound absorbing member 27 is made of an elastic resin material such as silicon, urethane, or acrylic, an insulating elastic rubber, a foam material, or the like. A thin substrate 22 such as an FPC on which the fixed contact 24 and the circuit electrode 23 are formed is placed on the surface of the sound absorbing member 27, and the dome spring 25 is disposed on the fixed contact 24. The dome spring 25 is fixed to the substrate 22 by a sheet material 26.

  The key switch module 21 having the above structure is bent and deformed by pressing the top P of the dome spring 25 with a finger or the like, and is brought into conduction by contacting the fixed contact 24. Since the pressing force at the time of such contact is absorbed by the sound absorbing member 27 through the thin substrate 22, the metallic contact sound at the time of clicking can be reduced. In the present embodiment, since the thin FPC is used for the substrate 22, the entire thickness of the base portion including the sound absorbing member 27 can be limited, and the entire thickness of the key switch module 21 can be suppressed within a certain range. It is.

  Further, the sound absorbing member 27 can be used as a substrate material, and the fixed contact 24 and the circuit electrode 23 can be directly formed on the upper surface of the sound absorbing member 27. As described above, since the entire substrate material is constituted by the sound absorbing member 27, the contact sound generated when the dome spring 25 contacts the fixed contact 24 is directly absorbed, so that the contact sound is higher than the embodiment shown in FIG. Can be reduced. Further, since the sound absorbing member 27 constitutes a part of the substrate, the number of components can be reduced and the entire key switch module can be thinned.

  FIG. 6 shows a cross-sectional structure of the key switch module 31 of the third embodiment. In the key switch module 31 of this embodiment, a sheet material for fixing the dome spring 35 on the substrate 32 is formed as the sound absorbing member 37. The sound absorbing member 37 is formed by thinly extending a resin material having elasticity such as silicon, urethane, acrylic, etc., insulating elastic rubber, foaming material or the like into a sheet shape. A circuit in which an adhesive layer is provided on the back surface of the sound absorbing member 37 thus formed into a sheet shape, and the outer periphery of the dome spring 35 is formed on the substrate 32 by covering the adhesive layer along the dome spring 35. It can be fixed on the electrode 33.

  In the key switch module 31 having the above-described structure, it is possible to absorb metallic bending deformation sound mainly generated when the dome spring 35 is pressed, and sound generated when the dome spring 35 returns to its original shape by releasing the press. Can also be absorbed. For this reason, it is suitable for applications where click operations occur frequently. Further, it is possible to reduce the sound generated when the dome spring 35 and the fixed contact 34 are in contact with each other. Furthermore, since the sound absorbing member 37 has a role of a fixing sheet for fixing the dome spring 35, the thickness of the entire key switch module 31 is not increased and the manufacturing is easy.

  The key switch modules 11, 21, 31 of the first to third embodiments have an effect of reducing the operation sound generated at the time of clicking. By combining two or more sound absorbing members in each embodiment, the operation sound can be reduced. Can be further reduced. As a first combination example, there is a key switch module having a structure in which a conductive first sound absorbing member is disposed between a fixed contact and a dome spring, and a sheet-like second sound absorbing member is disposed on the dome spring. . Further, as a second combination example, there is a key switch module having a structure in which a part or all of the substrate is configured by a first sound absorbing member and a sheet-like second sound absorbing member is disposed on a dome spring.

  By such a combination of sound absorbing members, it is possible to simultaneously reduce both the contact sound when contacting the fixed contact and the bending deformation sound of the dome spring, so that a key switch module with further silence can be obtained. .

DESCRIPTION OF SYMBOLS 1 Key switch module 2 Board | substrate 3 Circuit electrode 4 Fixed contact electrode 5 Movable contact electrode 6 Sheet material 11 Key switch module 12 Board | substrate 13 Circuit electrode 14 Fixed contact (fixed contact electrode)
15 Dome spring (movable contact electrode)
16 Sheet material 17 Sound absorbing member 18 Base portion 19 Conductive portion 20a, 20b Conductive rubber 21 Key switch module 22 Substrate 23 Circuit electrode 24 Fixed contact (fixed contact electrode)
25 Dome spring (movable contact electrode)
26 Sheet material 27 Sound absorbing member 31 Key switch module 32 Substrate 33 Circuit electrode 34 Fixed contact (fixed contact electrode)
35 Dome spring (movable contact electrode)
37 Sound absorbing member

Claims (8)

In a key switch module comprising a substrate and a key switch comprising a fixed contact electrode formed on the substrate and a dome-shaped movable contact electrode covering the fixed contact electrode,
A key switch module, wherein at least an upper surface of the fixed contact electrode is formed of a conductive sound absorbing member. The key switch module according to claim 1, wherein the sound absorbing member is formed of anisotropic conductive rubber disposed so as to cover the fixed contact electrode. The key switch module according to claim 2, wherein the anisotropic conductive rubber has concentric or dot electrode portions formed in an insulating resin. 2. The fixed contact electrode and a switch circuit electrode around the fixed contact electrode are provided on the substrate, and upper surfaces of the fixed contact electrode and the switch circuit electrode are formed by a conductive sound absorbing member. Key switch module as described. The key switch module according to claim 4, wherein the fixed contact electrode and the switch circuit electrode are formed of a conductive sound absorbing member. In a key switch module comprising a substrate and a key switch comprising a fixed contact electrode formed on the substrate and a dome-shaped movable contact electrode covering the fixed contact electrode,
A key switch module, wherein at least a part of the substrate is formed of a sound absorbing member. In a key switch module comprising a substrate and a key switch comprising a fixed contact electrode formed on the substrate and a dome-shaped movable contact electrode covering the fixed contact electrode,
The key switch module, wherein the movable contact electrode is covered with a sheet material formed of a sound absorbing member. The key switch module according to claim 6 or 7, wherein the sound absorbing member is formed of an elastic rubber member or a foamed member.

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