JP2006012678A - Pushing switch and its moving contact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a pushing switch having stable switching function, and assuring good contact between fixed contact and moving contact at the time of ON operation and the moving contact. <P>SOLUTION: The pushing switch comprises an annular first fixed contact 2 placed on a supporting member 1, a second fixed contact 3 placed on the supporting member 1 separately in the ring of the fixed contact 2, a moving contact 41 made of a domed conductive plate faced by these fixed contacts. On the inside wall of the dome of the moving contact 41, an annular projection 51 is made to increase contact area with the fixed contacts at the time of switching on. Moreover, a plurality of additional projections 53a to 53d are projected from respective inner rims of a plurality of contact holes 52a to 52d running through the plate part of the annular projection 51 toward the inside of the dome, so that they have shape of almost like a frame and sharp angled tips to improve contact with the fixed contact 3 and its switching function. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a pressure switch and a movable contact thereof, and more particularly, to a dome-shaped movable contact built-in type pressure switch used in an electronic device such as a mobile phone and an improvement of the movable contact.

  In recent years, in the field of electronic devices such as mobile phones, there has been a demand for miniaturization, thinness, and weight reduction, and the same requirements are increasingly increasing in the structure of the pressure switch used in these devices. As an example of one that meets this requirement, a dome-shaped movable contact built-in type pressure switch has been developed.

  The prior art (first conventional example) of this type of general pressing switch will be described. This switch is an annular first fixed contact, a disk-shaped second fixed contact juxtaposed inside thereof, and the two facing each other. For example, a circular dome-shaped movable contact arranged in such a manner is combined. The peripheral edge of the dome of the movable contact is in contact with the upper surface of the annular ring of the first fixed contact, and the dome apex of the movable contact is pressed and recessed in the direction of the second fixed contact so that its inner wall Is brought into contact with the second fixed contact, and the first fixed contact and the second fixed contact are in a conductive state (ON). Next, when the pressing is released, the movable contact returns to the original state, and the first fixed contact and the second fixed contact are in a non-conductive state (off).

  This type of switch is frequently turned on and off, and since the inflow and outflow of the outside air are repeated numerous times between the space inside the dome of the movable contact and the outside, the conductivity of the outside air is reduced. There is a problem that dust such as low or insulating dust gathers in the dome and causes contact failure between the fixed contact and the movable contact. The dust tends to accumulate particularly in the central portion of the second fixed contact, and there is a problem that a contact failure is likely to occur between the second fixed contact and the dome apex portion of the movable contact.

  Also, a flexible cover that is provided with a relatively large opening at the apex (center) of the dome-shaped movable contact, and the periphery of this opening is brought into press contact with the fixed contact, and is adhered to the outer wall of the movable contact with an adhesive. There is a conventional technique (second conventional example) in which a movable contact is held by a film (see, for example, FIG. 9 of Patent Document 1). In this prior art, the movable contact having such a relatively large opening is liable to be less durable against repeated pressing, and the adhesive of the cover film adheres to or is transferred to the fixed contact through the relatively large opening. There is a fear. Although it is conceivable that this adhesive is not applied in advance to the portion of the cover film corresponding to the hole, the adhesive film application pattern to the cover film is determined in advance, and the portion of the cover film without the adhesive during assembly And the movable contact need to be aligned, and its manufacture tends to be complicated.

Further, in order to solve the problem of the accumulation of dust in the central part of the fixed contact, the applicant of the present invention has an annular shape on the inner wall of the dome so as to avoid the apex (center) of the dome-shaped movable contact and surround the apex. A patent application has been filed regarding a movable contact provided with a protrusion and a pressure switch using the same (see Patent Document 2).
JP 2003-257280 A Japanese Patent Application No. 2004-115143

  The present invention relates to the improvement of the invention disclosed in Patent Document 2 and is intended to solve the problems as shown in the first and second conventional examples. It is an object of the present invention to provide a pressing switch having a stable switching function and a movable contact thereof that ensures a good contact state between the contact and the movable contact.

  The movable contact for a pressure switch according to the first aspect of the present invention comprises a dome-shaped flexible conductive plate material, and a dome peripheral portion for overlapping and contacting the upper surface of the annular first fixed contact; A dome apex for facing the central portion of the second fixed contact disposed in the ring of the one fixed contact, an annular projection formed on the inner wall of the dome so as to surround the apex, and the annular projection A plurality of contact holes formed through the plate portion, and a plurality of additional protrusions protruding substantially in a frame shape from the inner peripheral edges of the contact holes toward the inside of the dome and having sharp edges at the tips. It is characterized by.

  According to a second aspect of the present invention, in the movable contact according to the first aspect, the outer peripheral edge of the annular first fixed contact and the dome outer wall surface of the movable contact are bonded and the movable contact is attached to the first fixed contact. It is characterized by comprising a flexible cover film held on top.

  According to a third aspect of the present invention, in the movable contact according to the first or second aspect of the present invention, the annular protrusion is configured by coaxially arranging a plurality of annular protrusions. To do.

  According to a fourth aspect of the present invention, there is provided a pressure switch according to a fourth aspect of the present invention, comprising: an annular first fixed contact disposed on a support; A contact point and a dome-shaped movable contact point disposed opposite to the fixed contact point, and the movable contact point has the configuration of the movable contact point according to any one of claims 1 to 3. It is characterized by.

  According to the pressing switch and the movable contact of the present invention, the annular projection is provided on the inner wall of the movable contact made of the dome-shaped conductive plate material to increase the contact area with the fixed contact when the switch is turned on. The contact to the fixed contact by a plurality of additional protrusions projecting substantially in a frame shape from the inner peripheral edges of the plurality of contact holes formed in the plate material portion of the section toward the inside of the dome and having sharp edges at the tips. The switching function is stabilized and the on / off signal can be reliably transmitted to peripheral devices.

  FIG. 1 shows an embodiment of a pressure switch and a movable contact according to the present invention. FIG. 1 (a) is a top plan view of the movable contact, and FIG. 1 (b) is a longitudinal sectional view of the pressure switch. . Further, the movable contact shown in FIG. 1B is represented by a cross-sectional view taken along the line AA in FIG.

  For example, a circular annular first fixed contact 2 is disposed on a support 1 such as an insulating substrate used for a printed wiring board. Further, for example, a disk-shaped second fixed contact is provided on the support 1. 3 are spaced apart from the inner wall of the first fixed contact 2 and are coaxially juxtaposed with each other. The fixed contacts 2 and 3 are formed of, for example, a copper layer plated with gold.

  Further, the movable contact 41 arranged in a coaxial relation position facing the first and second fixed contacts 2 and 3 is formed in a reversible dome shape whose planar shape is, for example, a circular shape, A circular dome peripheral edge portion 41a that is in contact with the upper surface of the first fixed contact, a dome apex portion 41b that faces the central portion of the second fixed contact 3, and an inner wall of the dome so as to surround the apex portion. An annular projection 51 is provided.

  The movable contact 41 is made of a metal conductive plate material such as stainless steel or phosphor bronze having flexibility and elasticity. Here, a SUS301 plate material having a plate thickness of about 50 μm is formed into a dome shape by, for example, pressing, and the annular protrusion 51 is also curved and formed, for example, in a circular arc shape in a longitudinal section so as to have an annular groove 51a on the outside of the dome and an annular protrusion 51b on the inside of the dome.

  A plurality of circular contact holes 52a, 52b, 52c, and 52d are formed through the plate member at a plurality of positions along the ring of the annular protrusion 51, for example, at four positions at intervals of about 90 degrees. On the inner peripheral edge of each of the contact holes 52a to 52d, circular frame-shaped additional protrusions 53a, 53b, 53c and 53d are formed which protrude inward from the protrusion 51b of the protrusion 51. These additional protrusions 53a to 53d are all formed at an acute angle of 90 degrees or less, for example, and have a shape with a sharp tip, and can be elastically deformed in accordance with the pressing force in the same manner as the plate material. The protrusion heights of the additional protrusions 53a to 53d are such that when the movable contact is pressed, the additional protrusions 53a to 53d first contact the second fixed contact 3, and then the annular protrusion end of the annular protrusion 51 The height of the ridge line 51b is set such that it can contact the second fixed contact 3.

  The flexible cover film 54 adhered to cover the outer peripheral edges of the support 1 and the first fixed contact 2 and the dome outer wall surface of the movable contact 41 is one in which an adhesive is uniformly applied to one entire surface in advance. Is prepared, and the movable contact 41 is held on the first fixed contact by adhesion with the adhesive.

  Here, as an example of the shape and dimensions of the movable contact 41, the outer diameter of the circular dome peripheral portion 41a is about 4 mm, and the annular protrusion 51 has an inner diameter of about 0.6 mm and an outer diameter of about 0.6 mm. It is formed so that the ring diameter of the ring-shaped protruding end portion 51b having a circular cross section of 1.4 mm is about 1.0 mm. Therefore, the annular protrusion 51 has a ring width of about 0.4 mm, which is considerably larger than that shown in Patent Document 2 (ring width of about 0.1 mm). It is easy to bend with respect to the pressing load. The height of the annular protruding end 51b is about 13 μm. The contact holes 52a to 52d have a hole diameter of about 0.2 mm, and the additional protrusions 53a to 53d have a height of about 10 μm or less.

  Therefore, the switching function will be described. When no operation is performed, the additional protrusions 53a to 53d are separated from the upper surface of the second fixed contact 3, and the first fixed contact 2 and the second fixed contact 3 are in an off state. When the apex 41b of the movable contact 41 or the vicinity thereof is pressed inward from the outside of the dome with, for example, a finger or via a push button, the outer wall of the dome is bent and recessed, and first, the additional protrusions 53a to 53d are The ridgeline of the annular projecting end 51b of the annular projecting portion 51 is brought into contact with the second fixed contact 3 while being in contact with the second fixed contact 3 and then being pressed, and the first fixed contact 2 -the second fixed contact. The contact 3 is turned on. When this pressing is released, the movable contact 41 is restored to the original dome shape and returns to the off state.

  If the surface of the second fixed contact 3 has flexibility due to gold plating or the like, the pressing of the additional protrusions 53a to 53d is flexibly received, and the ridgeline of the annular protruding end 51b contacts the second fixed contact 3. Can increase the sex. Further, even when the fixed contact is formed of a flexible conductive resin like a membrane switch, the additional projecting portion sinks into the conductive resin due to the pressing and includes the ridge line portion of the annular projecting end portion 51b. Improves contact and reliability.

  According to the invention of this embodiment, the protruding end portion 51b of the protruding portion 51 is located at a radius of about 0.3 mm from the center of the dome apex portion 41b, and avoids the central portion of the second fixed contact 3 where dust is likely to accumulate. Since the projection 51 is annular, the contact area with the second fixed contact 3 is not limited to the fact that the contact state with the second fixed contact 3 is hardly affected by dust. Since it is much larger than the above-described conventional example, a reliable and stable switching-on characteristic can be obtained.

  In addition, since each of the additional protrusions 53a to 53d penetrates the dust and reliably contacts the second fixed contact 3, the influence of the dust is reduced as compared with the prior art, and a reliable and stable switching function is achieved. can get.

  Moreover, since the frame-like additional protrusions 53a to 53d are arranged in place of a plurality of (for example, four) portions of the ridge line of the annular protruding end portion 51b, these frame-like portions contact the fixed contact. In addition, the contact area can be made larger than the contact of only the ridge line portion of the annular protrusion 51b.

  Therefore, in order to deepen the understanding of such advantages, a comparison experiment result of switching characteristics with respect to dust such as dust in the press switch of the embodiment and the conventional example will be described.

  In this experiment, as a tool for pressing the movable contact, a pressure rod having a tip curvature of 0.2 mm and a diameter of 1 mm is prepared, and by pressing the apex of the movable contact with the tip of the pressure rod, At this time, when a glass cloth piece is used as the dust such as insulating dust in the dome of the movable contact, and there is dust, there is no pressing load Pa (N) and dust necessary for obtaining the ON state. The pressure load difference ΔP (= Pa−Pb) with the pressure load Pb (N) necessary for obtaining the ON state was measured.

In Table 1 below, the first conventional example (without dome apex opening), the second conventional example (with dome apex opening) and the present invention (embodiment) are compared, and the glass cloth pieces are compared. The result of measuring the pressure load difference ΔP (N) is shown for the distribution state when the movable contacts are accumulated at the center in the dome and scattered as a whole.

  Also from this experimental result, in the switch of the present invention of the above embodiment, the pressure load difference ΔP (N) shows a small value of about zero in the case of central integration and about 0.195 (N) in the total scattering. It is understood that stable switching-on characteristics are obtained that are less affected by the dust, regardless of the dust distribution state, as compared with the first and second conventional examples.

  Further, as shown in Table 1, the pressure load difference ΔP of the first conventional example is 0.513 and 0.543, and when the contact is difficult due to dust, The pressing load Pa must be increased, the pressing load difference ΔP value increases, and the load value that is normally turned on by clicking shifts to an undesirably large value, so that a good switch response cannot be obtained, Although the click feeling (switch operability) is lowered, the switch according to the embodiment of the present invention has a small pressing load difference ΔP as described above, and the click feeling is improved as compared with the conventional example.

  Further, in comparison with the second conventional example, the movable contact of the above embodiment has a vertex portion, which avoids local stress concentration and has high durability, and the contact holes 52a to 52d are formed of the annular protrusion 51. Since it is provided at the bottom, there is a gap between the adhesive and the fixed contact even if the cover film is attached, and the adhesive does not adhere to the fixed contact. Regarding the presence or absence of adhesion of the adhesive to the fixed contact, it was confirmed in the comparative experiment that adhesion occurred in the second conventional product, but did not occur in the embodiment product. Moreover, it is not necessary to change the application pattern of the pressure-sensitive adhesive on the cover film, and there is little risk of inconvenience in manufacturing.

  In addition, even when it is partially pressed (eccentrically pressed) at a position off the center of the movable contact 41, the apex 41b of the movable contact and its vicinity are work-hardened by the formation of the annular protrusion 51. Since the pressing force in the direction along the central axis is transmitted almost uniformly to the entire ring of the protrusion 51 and the entire annular protrusion is displaced substantially uniformly downward, the deformation behavior of the movable contact 41 presses the center. As a result, the operational feeling is significantly improved as compared with the conventional example.

  In the above-described embodiment, the annular protrusion 51 is formed in a single annular shape, but a configuration in which a plurality of annular protrusions are coaxially arranged side by side, in other words, a double or triple coaxial arrangement, etc. The configuration may be a multiple ring shape. In this case, the contact area with the second fixed contact 3 is increased, and the switching-on characteristics are further improved.

  In the above-described embodiment, the first and second fixed contacts and the movable contact have a circular planar shape. However, various shapes such as an ellipse, a barrel shape, and a substantially rectangular shape with corners in an arc shape can be used. Also good. Although the shape of the movable contact is expressed as a dome shape, it can be freely expressed as a dish shape, a bowl shape, a diaphragm shape, etc., and has the same shape and function in light of the objects and effects of the present invention. The thing was generically expressed as a dome shape.

  The terms such as the center, the center point, the center axis, or the central portion expressed in the above embodiment may not be circular but may be partially deformed. It can be understood that it represents the best pressing position in terms of the operation of the pressing switch without being particular about the geometric position, and the term apex part is not limited to the arc shape, but may be flat. In this case as well, it may be interpreted as a portion that exists in the best pressing position functionally.

  In general, the fixed contact and the movable contact of the pressing switch are housed in a housing (not shown), and the pressing operation on the movable contact is performed via a push button or a stem (not shown).

It is a figure for demonstrating the press switch and movable contact which concern on one Embodiment of this invention, Fig.1 (a) is an upper top view which shows the movable contact, FIG.1 (b) is a longitudinal cross-section which shows the press switch FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 1st fixed contact 3 2nd fixed contact 41 Movable contact 41a Dome peripheral part 41b Dome vertex 51 Annular projection 51a Annular groove 51b Annular protrusion 52a thru 52d Contact hole 53a thru 53d Additional projection 54 Flexible Cover film

Claims (4)

  A dome-shaped flexible conductive plate material, a dome peripheral portion for contacting the upper surface of the annular first fixed contact, and a second fixed contact disposed in the ring of the first fixed contact A dome apex portion for facing the center portion, an annular protrusion formed on the inner wall of the dome so as to surround the apex portion, a plurality of contact holes formed through the plate portion of the annular protrusion, and these A movable contact for a pressure switch, comprising: a plurality of additional protrusions protruding substantially in a frame shape from each inner peripheral edge of the contact hole toward the inside of the dome and having sharp edges at the tips.   2. The flexible contact film according to claim 1, wherein the flexible contact film is adhered to cover an outer peripheral edge of the annular first fixed contact and a dome outer wall surface of the movable contact and holds the movable contact on the first fixed contact. And a movable contact for a pressure switch.   The movable contact according to claim 1 or 2, wherein the annular protrusion has a configuration in which a plurality of annular protrusions are coaxially arranged side by side. An annular first fixed contact disposed on the support, a second fixed contact disposed on the support spaced apart from the first fixed contact in a ring of the fixed contact, and opposed to the fixed contacts A dome-shaped movable contact, and the movable contact has the movable contact configuration according to any one of claims 1 to 3.

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