JP2005302454A - Push switch and its movable contact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a push switch and its movable contact that secures a good contact state between a stationary contact and a movable contact during on-operation, and has a stable switching function. <P>SOLUTION: A push switch includes an annular first stationary contact 2 arranged on a base material 1, a second stationary contact 3 arranged on the base material 1 distanced therefrom within the stationary contact 2, and a domed movable contact 4 arranged opposite to these stationary contacts. The movable contact 4 has a dome peripheral edge 4a that is laid to come into contact with the top of the first stationary contact, and an opposite dome peak 4b in the middle of the second stationary contact, and an annular protrusion 5 formed on the inner wall of the dome so as to surround the peak. The annular protrusion 5 is separated from the second stationary contact 3 during non-operation, and comes into contact with the contact 3 during on-operation. <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 dome periphery of the movable contact is in contact with the top surface of the annular ring of the first fixed contact, and the top of the dome of the movable contact or the vicinity thereof is pressed and recessed in the direction of the second fixed contact. A part of the 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. The movable contact of the first conventional example has a smooth curved surface on the entire inner wall surface of the dome, which is referred to as a plane type here.

 In addition, a conventional technique (second conventional example) for improving such a problem is known (see, for example, Patent Document 1). In this second conventional example, the combination configuration of the fixed contact and the movable contact is substantially the same as that of the first conventional example, but this movable contact is provided with a plurality of projections, for example, three points on the inner wall surface of the dome, The contact with the fixed contact is made by these protrusions. The plurality of protrusions are provided at positions avoiding the apex portion (central portion) of the dome so as to avoid the influence of dust on the contact state when the movable contact and the fixed contact are turned on. However, even if such dust tends to accumulate in the central portion, it may be scattered outside the central portion. In such a case, it is difficult to increase the contact area from the beginning. It tends to cause a decline in sex. If each of the plurality of protrusions is sharp like a piercing tip, it is considered that the dust is likely to penetrate through contact due to stress concentration at the time of pressing, but when the dust is relatively coarse, such penetration may occur. There is a problem that the number of protrusions that can contact the fixed contact is reduced, and the contact area between the movable contact and the fixed contact necessary for ensuring the reliability of on-transmission is often insufficient.

By the way, the problems of the first and second conventional examples can also be understood from comparative experiment data with the present invention described later.
JP 2000-322974 A

  The present invention has been made to solve the problems as shown in the first and second conventional examples, ensuring a good contact state between the fixed contact and the movable contact at the time of an on operation, An object of the present invention is to provide a pressing switch having a stable switching function and a movable contact thereof.

  The movable contact for the pressure switch according to the first aspect of the present invention is formed in a dome shape made of a flexible plate material, and a dome peripheral portion for overlapping and contacting the upper surface of the annular first fixed contact, It has a dome apex part for making it oppose the center part of the 2nd fixed contact arranged in the ring of the 1st fixed contact, and an annular projection part formed in the inner wall of the dome so as to surround this apex part. To do.

  According to a second aspect of the present invention, in the movable contact according to the first aspect of the invention, the annular projection is configured by coaxially arranging a plurality of annular projections. .

  According to a third aspect of the present invention, in the movable contact according to the first or second aspect, the annular protrusion is formed by forming a dome wall so that an annular groove is provided on the outer dome wall of the movable contact. It is characterized by being formed.

  According to a fourth aspect of the present invention, in the movable contact according to any one of the first to third aspects of the present invention, the ring-shaped projecting portion has a ring center axis coaxially with the center axis of the dome. It is characterized by being arranged.

  According to a fifth aspect of the present invention, in the movable contact according to any one of the first to fourth aspects, the diameter D (mm) at the peripheral edge of the movable contact is in the range of about 2 to 5 mm. The projecting end ring diameter d (mm) of the annular protrusion is set such that the ratio (d / D) to the peripheral edge diameter D is in the range of about 0.0625 to 0.375. Is.

  According to a sixth aspect of the present invention, in the movable contact according to any one of the first to fourth aspects, the diameter D (mm) at the periphery of the movable contact is in the range of about 2 to 5 mm. The height h (μm) of the annular protrusion is set such that the ratio (h / D) to the peripheral edge diameter D is in the range of about 1.25 to 15.

  According to a seventh aspect of the present invention, in the movable contact according to any one of the first to fourth aspects, the diameter D (mm) at the periphery of the movable contact is in the range of about 2 to 5 mm. The projecting end ring diameter d (mm) of the annular protrusion is set such that the ratio (d / D) to the peripheral edge diameter D is in the range of about 0.0625 to 0.375. The height h (μm) is set such that the ratio (h / D) to the peripheral edge diameter D is in the range of about 1.25 to 15.

  According to an eighth aspect of the present invention, there is provided a pressure switch according to an eighth aspect of the present invention, wherein an annular first fixed contact disposed on a support and a second fixed disposed on the support spaced apart from the first fixed contact in the ring of the fixed contact. A contact point and a dome-shaped movable contact point disposed opposite to the fixed contact point, and the movable contact point has the structure of the movable contact point according to any one of claims 1 to 7. It is characterized by.

  According to the pressure switch and the movable contact of the present invention, the switching function is stabilized by providing an annular protrusion on the inner wall of the dome-shaped movable contact and increasing the contact area with the fixed contact when the switch is turned on. There is an effect that reliable on / off signal transmission to peripheral devices can be performed.

  Hereinafter, first and second embodiments of the pressing switch and the movable contact according to the present invention will be described with reference to FIGS. 1 to 10.

 FIG. 1 is a longitudinal sectional view of a press switch showing a first embodiment of the present invention, and FIG. 2 is a plan view of each member showing an exploded configuration of the press switch. As shown in FIG. 1 and FIG. 2A, 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, On the support 1, for example, a disk-shaped second fixed contact 3 is juxtaposed away from the inner wall of the first fixed contact 2.

 Further, as shown in FIGS. 1 and 2 (b), the movable contact 4 disposed to face the first and second fixed contacts 2 and 3 has a planar dome shape, for example, a circular shape. The movable contact 4 is formed such that a circular dome peripheral edge portion 4a that is in contact with the upper surface of the first fixed contact, a dome apex portion 4b that faces the central portion of the second fixed contact 3, and this An annular projection 5 is formed on the inner wall of the dome so as to surround the apex. The first and second fixed contacts 2 and 3 and the movable contact 4 are in a coaxial relationship with each other about a center line indicated by a one-dot chain line in FIG. The movable contact 4 is formed by forming a flexible and elastic stainless steel (for example, SUS301) plate having a thickness of about 50 μm into a dome shape with the annular protrusion 5 by, for example, pressing. The outer diameter of the peripheral edge 4a is about 4 mm here. The protrusion 5 is shaped so that the longitudinal section is bent or bent in a substantially U shape or substantially V shape at the time of the pressing, and an annular groove 5a recessed in the outer wall of the dome protrudes into the inner wall of the dome. Each of the protrusions 5b has a height of about 13 μm.

 The protrusion 5 is formed such that the inner diameter of the ring is about 0.9 mm, the outer diameter is about 1.1 mm, and the ring diameter of the protrusion 5b is about 1.0 mm.

  Accordingly, the switching function will be described. The protrusion 5 is separated from the upper surface of the second fixed contact 3 when no operation is performed, and the first fixed contact 2 and the second fixed contact 3 are in an off state. When the apex 4b of 4 or the vicinity thereof is pressed from the outside of the dome toward the inside by, for example, a finger, the outer wall of the dome is bent and recessed, and the protruding end 5b of the protruding portion 5 is pressed against the second fixed contact 3. Thus, the first fixed contact 2 and the second fixed contact 3 are turned on. When this pressing is released, the movable contact 4 is restored to the original dome shape and returns to the off state.

  According to the invention of this embodiment, the protruding end portion 5b of the protruding portion 5 is located at a radius of about 0.5 mm from the center of the dome apex portion 4b, and avoids the central portion of the second fixed contact 3 where dust is likely to accumulate. Since the protrusion 5 is annular, the contact area with the second fixed contact 3 is not limited to the influence of dust. Since it is much larger than the above-described conventional example, a reliable and stable switching-on characteristic can be obtained. Further, when the annular protrusion 5 is bent in a substantially V-shaped longitudinal section and the protruding end 5b has an acute angle, the second fixed contact is more easily penetrated and pushed away than the U-shaped. The degree of contact with 3 is further improved.

 Therefore, in order to deepen the understanding of such advantages, a comparison experiment result of switching characteristics with respect to dust in the press switches of the first embodiment and the conventional example will be described with reference to FIG. During the switch-on operation, if the pressing load on the movable contact exceeds a certain value, the movable contact 4 and the second fixed contact 3 are always in good contact with each other regardless of the magnitude of the load or the presence or absence of dust. It is desirable that a state be obtained. FIG. 3 is data showing the result of a comparative experiment based on this viewpoint, and shows the pressing load Pa (N) required to obtain an ON state when there is an insulating foreign material, here, dust, in the dome of the movable contact. The result obtained by measuring the pressure load difference ΔP1 (= Pa−Pb) with the pressure load Pb (N) necessary for obtaining the ON state in the absence of dust is shown. The comparison targets shown here are the above-described first conventional example (plane type), the second conventional example (three-point protrusion), and the present invention (first embodiment). Bencotton, polyethylene terephthalate (PET), and glass cloth dust were used as the types of dust, respectively.

 Also from this experimental result, in the switch of the present invention of the first embodiment, the pressure load difference ΔP1 shows no change regardless of the presence or absence of Bencotton, and the first and second for PET. It shows a small value of about 1/8 to 1/9 compared to the conventional example, and the glass cloth also shows a much smaller value than the first and second conventional examples, and is affected by the presence of dust. It is understood that stable switching-on characteristics are obtained.

 Next, in this kind of pressure switch, improvement of the touch feeling or click feeling of the finger in the switch operation and the improvement of the switching-on characteristic against the positional deviation (eccentricity) of the pressing load with respect to the movable contact are desired. A comparative experiment between the related first embodiment and the conventional example will be described with reference to FIGS.

 First, FIG. 4 and FIG. 5 show the click feeling. FIG. 4 shows that a pressing rod having a tip curvature of 0.2 mm and a diameter of 1 mm is prepared as a tool for pressing the movable contact, and the tip of the pressing rod. Load-displacement characteristic diagram showing the relationship between the pressing load (N) generated by pressing the apex of the movable contact 4 toward the second fixed contact 3 and the displacement of the apex of the movable contact 4 (mm) It is. In the characteristic curve of FIG. 4, the displacement of the apex of the movable contact 4 continues from the start of pressing of the pressing switch of the first embodiment to the minimum value P2 (N) through the load maximum value P1 (N), and the minimum value is reached. After P2, even if the load is increased, the displacement is only slightly increased. In general, it is said that the larger the load difference ΔP2 (N) (= P1−P2) between the maximum value P1 (N) and the minimum value P2 (N), the better the click feeling is obtained. A click rate CR (%) (= ΔP2 / P1) indicating a ratio of the load difference ΔP2 to the maximum value P1 is generally used as a unit representing the touch. FIG. 5 shows a numerical comparison of the load difference ΔP2 (N) and the click rate CR (%) in the load-displacement characteristics between the first embodiment and the first conventional example. The load of the first embodiment is shown in FIG. The difference ΔP2 and the click rate CR are about 1.8 times larger than the first conventional example, indicating that the click feeling is remarkably high.

  Next, switching-on characteristics with respect to positional deviation (eccentricity) of the pressing load with respect to the movable contact will be described with reference to FIGS. As shown in FIG. 6, nine pressing measurement positions (indicated by black dots (·) in the figure) at 0.1 mm intervals from the center of the vertex 4 b of the movable contact 4 toward the dome peripheral edge 4 a. The relationship between the amount of eccentricity of the pressing position and the click rate CR (%), that is, the eccentric characteristic, was tested by pressing the movable contact with the tip of the pressing bar, and the result is shown in FIG. According to this result, the click rate CR (%) of the present invention of the first embodiment is much higher than that of the first conventional example, and the click rate CR (%) with respect to the eccentric amount of the pressing position of the movable contact. ) Is understood to be small. By the way, the click rate CR is practically set to have a lower limit of about 30% (lower limit line is indicated by a broken line in the figure). Therefore, when viewed in the practical range, the eccentric position as the allowable range is In contrast to the conventional example of about 0.5 mm, the present invention of the first embodiment can provide a good click feeling over a wide range of about 0.7 mm and about 0.2 mm. That is, even when the click position deviates from the center of the apex portion 4b of the movable contact, a good click feeling and a reliable and stable contact between the movable contact and the fixed contact can be obtained, and the switching-on characteristics are remarkably improved as compared with the prior art. The

  FIG. 8 shows the basic data of the characteristic curve of FIG. 7 in detail. The click rate CR and the reduction rate (%) with respect to the eccentric amount of the pressing position are numerically shown, and the present invention of the first embodiment It can be seen that the reduction rate (%) of the click rate CR is low as a whole, and in particular, the reduction rate (%) is remarkably low up to an eccentric position of about 0.5 mm, and particularly excellent switching-on characteristics can be obtained in this range.

  In the experiments of FIGS. 4 to 8, the first conventional example is shown as a conventional example as a conventional example, but the first conical protrusion provided on the inner wall of the dome apex portion of the movable contact is also the first example. The result is almost the same as the conventional example.

  Here, the effect is further considered. In general, it is known that this kind of movable contact is more likely to jump and buckle as the tensile residual internal stress of the plate material is present on the center side of the fixed contact. From this point of view, in the first embodiment, the annular protrusion 5 is molded at a position coaxial with the movable contact 4, so that the tensile residual internal stress is higher in the movable contact 4 than in the conventional example. It is considered that the jumping buckling phenomenon is liable to occur and the switch operation feeling is improved. Further, since the apex portion 4b of the movable contact and its vicinity are work-hardened by the formation of the annular protrusion 5, even if it is partially pressed at a position off the center of the movable contact 4, the direction along the central axis Is transmitted almost uniformly to the entire ring of the projection 5 and the entire annular projection is displaced almost uniformly downward, so that the deformation behavior of the movable contact 4 is the same as when the central portion is pressed. It is considered that the operation feeling is remarkably improved as compared with the conventional example.

  Since the dimension of the push switch is set according to the application, the dimension setting will be described with reference to FIG. FIG. 9 is a schematic diagram, in which the upper circular display in the drawing shows the upper planar shape of the movable contact 4, and the lower arched display in the drawing is a longitudinal section with the dome of the movable contact 4 turned down. Is shown. In FIG. 9, the diameter of the peripheral edge 4a of the movable contact 4 is indicated by D (mm), the ring diameter of the protruding end 5b of the annular protrusion 5 is indicated by d (mm), and the height of the annular protrusion 5 is indicated by h (μm). Then, when the peripheral edge diameter D of the movable contact is set in a range of about 2 to 5 mm, the ratio of the protrusion end ring diameter d (mm) to the peripheral edge diameter D (d / D) is about 0.0625 or more. It is set to be in the range of 0.375. If the value is set to be equal to or higher than the lower limit in this range, the above-described adverse effect of the on-characteristic due to dust can be avoided. If the upper limit is exceeded, the outer diameter of the second fixed contact 3 is exceeded and contact cannot be maintained.

  When the peripheral edge diameter D is in the same range, the protrusion height h (μm) is set so that the ratio (h / D) to the peripheral edge diameter D is in the range of about 1.25 to 15. Yes. In this case, h (μm) and D (mm) are different in dimension from each other, and are shown as a ratio of only the numerical values. The ratio (h / D) × 1/1000 is indicated. When the lower limit value for the protrusion height h is exceeded, when there is dust at a position facing the protrusion 5, it is possible to ensure a height that can reliably contact the second fixed contact beyond this thickness. When the upper limit is exceeded, the peripheral edge 4a of the movable contact jumps up with the protrusion 5 as a fulcrum and may move away from the first fixed contact 2 and lose the switch function.

  If the ratio (d / D) and / or ratio (h / D) is set as described above, all of the movable contacts with various peripheral diameters D according to the application of the switch can be used. In addition, it is possible to provide a movable contact and a press switch having stable contact sensitivity and excellent click feeling during switching operation.

  FIG. 10 is a longitudinal sectional view of a push switch showing a second embodiment of the present invention. Components similar to those in the first embodiment are denoted by the same reference numerals and characteristic portions will be described. In this example, the movable contact is formed by attaching a film-like movable contact 4A to the surface of a flexible insulating film 4B such as polyethylene terephthalate (PET) by circuit printing technology, for example, by silver paste printing. It is formed by molding into a dome shape with a protrusion 5A. The movable contact 4A is in the form of a film, but is handled as a synonym for the flexible plate material in the first embodiment. According to the second embodiment, when a plurality of push switches are formed side by side on a support such as a common circuit board, there are advantages such as high productivity and low cost manufacturing.

  In each of the above-described embodiments, the annular protrusions 5 and 5A are 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, two or three coaxially arranged mutually. It may be configured to be a multiple ring shape such as a heavy, and in this case, the contact area to the second fixed contact 3 is increased, and the switching-on characteristics are further improved.

  In each of the above embodiments, the first and second fixed contacts and the movable contact have a circular planar shape. However, the first and second fixed contacts and the movable contact have various shapes depending on the application, such as an ellipse, a barrel shape, and a substantially rectangular shape with corners arced. May be. 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 an arc shape, and the cross-sectional shape 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 longitudinal section showing a press switch concerning a 1st embodiment of the present invention. It is a top view which decomposes | disassembles and shows the press switch which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the switching characteristic of the press switch which concerns on the 1st Embodiment of this invention. It is a characteristic curve figure for demonstrating the click feeling of the press switch which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating numerically the click feeling of the press switch which concerns on the 1st Embodiment of this invention. It is a figure for demonstrating the press measurement position with respect to the movable contact of the press switch which concerns on the 1st Embodiment of this invention. It is a characteristic curve figure which shows the relationship between the press position of the press switch which concerns on the 1st Embodiment of this invention, and a click rate. It is a figure for demonstrating numerically the relationship between the press position of the press switch which concerns on the 1st Embodiment of this invention, and a click rate. It is the schematic for demonstrating the dimension of the movable contact of the press switch which concerns on the 1st Embodiment of this invention. It is a longitudinal cross-sectional view which shows the press switch which concerns on the 2nd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Support body 2 1st fixed contact 3 2nd fixed contact 4, 4A Movable contact 4a Dome peripheral part 4b Dome vertex part 5 Annular protrusion 5a Annular groove 5b Annular protrusion

Claims (8)

A dome formed of a flexible plate material, and 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 movable contact for a pressure switch, comprising: a dome apex portion for facing a central portion; and an annular protrusion formed on an inner wall of the dome so as to surround the apex portion. 2. The movable contact for a press switch according to claim 1, wherein the annular protrusion is configured by coaxially arranging a plurality of annular protrusions. 3. The movable contact according to claim 1, wherein the annular protrusion is formed by forming a dome wall so that an annular groove is provided on an outer dome wall of the movable contact. A movable contact for the pressure switch. 4. The movable contact according to claim 1, wherein the annular protrusion has a ring center axis coaxially arranged with a center axis of the dome. A movable contact for the pressure switch. 5. The movable contact according to claim 1, wherein a diameter D (mm) at a peripheral edge of the movable contact is in a range of about 2 to 5 mm, and the projecting end ring of the annular projection is formed. The diameter d (mm) is set such that a ratio (d / D) to the peripheral edge diameter D is in a range of about 0.0625 to 0.375. 5. The movable contact according to claim 1, wherein a diameter D (mm) at a peripheral portion of the movable contact is in a range of about 2 to 5 mm, and a height h of the annular protrusion is set. (Μm) is set so that a ratio (h / D) to the peripheral edge diameter D is in a range of about 1.25 to 15; 5. The movable contact according to claim 1, wherein a diameter D (mm) at a peripheral edge of the movable contact is in a range of about 2 to 5 mm, and the projecting end ring of the annular projection is formed. The diameter d (mm) is set so that the ratio (d / D) to the peripheral edge diameter D is in the range of about 0.0625 to 0.375, and the height h (μm) of the annular protrusion is the peripheral edge A movable contact for a press switch, characterized in that a ratio (h / D) to a part diameter D is set to be in a range of about 1.25 to 15. 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 7.

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