JPH05342943A - Pushbutton switch - Google Patents

Abstract

PURPOSE:To provide a pushbutton switch which can be formed thinner without generating troubles in elevation action of a keytop by using a member for holding the keytop to be freely elevated without standing guide walls in a housing, and composing a structure in which the holding member is hard to be removed from the housing. CONSTITUTION:An outer leg member 29 and an inner leg member 32 of link members 26, 27 are connected to each other to set a cross angle is changeable in accordance with a height position of a keytop 23. Engagement protrusions 29a, 32a are engaged with engagement recesses 22b, 22c in a housing 22, so both leg members 29, 32 are position-regulated to be prevented from dissociation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a push button switch used as a key switch of a keyboard device, and more particularly to a push button switch suitable for thinning.

[0002]

2. Description of the Related Art FIG. 7 is a sectional view showing a conventional example of a push button switch of this type.

In FIG. 1, reference numeral 1 is a support plate made of a hard material such as a metal plate, and a membrane switch 2 is mounted on the support plate 1. This membrane switch 2
Is such that the movable contact 4 provided on the lower surface of the flexible upper sheet 3 faces the fixed contact 6 provided on the upper surface of the lower sheet 5, and the spacer 7 is provided between both sheets 3 and 5. It is a switch element. Also, the membrane switch 2
A synthetic resin housing 8 having an annular guide wall 8a standing thereon is placed on the upper side, and an inner opening 8b of the guide wall 8a is located above the movable contact 4. The stem 10 projecting from the central portion of the back surface of the synthetic resin key top 9 is inserted into the opening 8b so as to be slidable along the inner wall surface of the guide wall 8a. A coil spring 11 functioning as an actuator is mounted inside the box by strong fitting. The return spring 12 installed between the housing 8 and the key top 9 outside the guide wall 8a is for urging the key top 9 upward.

In the push button switch thus constructed, when the operator pushes the key top 9 against the elastic force of the return spring 12, the stem 10 descends along the inner wall surface of the guide wall 8a. The coil spring 11 in the stem 10 comes into contact with the upper sheet 3 of the membrane switch 2 and is gradually compressed. Therefore, when the key top 9 is pushed for a predetermined stroke, the elastic force of the coil spring 11 causes the upper sheet 3 to bend downward, the movable contact 4 comes into contact with the fixed contact 6, and switching from off to on is performed.

Further, when the operator removes the pressing operation force on the key top 9 in such an ON state, since the key top 9 is pushed up to the initial position by the elastic force of the return spring 12, the coil spring 11 is moved from the upper seat 3. The upper sheet 3 is separated from the fixed contact 6 and the movable contact 4 is separated from the fixed contact 6 to return to the OFF state shown in FIG.

[0006]

By the way, as for push button switches incorporated in keyboard devices and the like, there is an increasing demand for thinning of the push button switches in the past. Since the key top 9 is held in the housing 8 so as to be able to move up and down by slidingly contacting the inner wall surface of the guide wall 8a, the height of the guide wall 8a is ensured in order to ensure a desired operating stroke and to make the push button switch thin. If the size is suppressed as much as possible, the amount of insertion of the stem 10 into the guide wall 8a will inevitably decrease. As a result, due to the minute clearance between the stem 10 and the guide wall 8a required for sliding, the key top 9
Is easily tilted with respect to the housing 8, so that, for example, when the operator pushes the edge of the key top 9 to perform an end push, the stem 10 is caught by the guide wall 8a, which hinders the vertical movement of the key top 9. Therefore, it is easy to cause deterioration of operation feeling and malfunction.

The present invention has been made in view of the above problems of the prior art, and an object of the present invention is to provide a push button switch which can be made thinner without hindering the lifting operation of the key top.

[0008]

SUMMARY OF THE INVENTION The above-mentioned object of the present invention is to support a pair of external leg pieces, which have an outward engaging projection at their tips and extend in parallel, on one side of the back surface of the key top. A first link member having a shape in which a first support portion is bridged;
A second pair of inner leg pieces, each having an inward engaging projection at its tip end and extending in a direction that is parallel to and intersects the inner leg piece with respect to the outer leg piece, is provided for supporting the other side of the back surface of the key top. A second link member having a bridging support portion, and the outer leg piece and the inner leg piece are connected to each other at their intersecting portions so that the angle at which they intersect with each other can be changed. The link member is urged upward by an elastic member, and the housing is provided with a pair of inward engaging recesses that are engageable by loosely inserting the engaging protrusions of the outer leg pieces and the inner leg pieces. This is achieved by providing a pair of outward engaging recesses that can be engaged by loosely inserting the engaging protrusions.

[0009]

According to the above means, the supporting portions of the first and second link members can support the key top by receiving the elastic force of the elastic member, and the key top is provided with a pressing operation force. When the first and second support parts are pushed in,
The outer leg piece and the inner leg piece that are crossed and connected in a substantially X shape gradually increase the angle at which they cross when viewed from the key top side, but both link members supporting the key top are folded in this way. Even so, since the position of the engaging projection of each leg can be regulated by the housing, the key top can be lowered straight without the guide wall being erected on the housing. Furthermore, by engaging the outward engaging projection of the outer leg piece with the inward engaging recess of the housing,
Further, by engaging the inward engaging projection of the inner leg piece with the outward engaging recess of the housing, the position of the outer leg piece and the inner leg piece connecting the intersecting portions is regulated from the separating direction. As a result, the connection between these two leg pieces is ensured, and it becomes difficult for each engagement protrusion to come off from the corresponding engagement recess.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. Here, FIG. 1 is a plan view showing an internal structure of a push button switch as an embodiment, FIG. 2 is a sectional view of the push button switch in an off state, FIG. 3 is a sectional view of the push button switch in an on state, and FIG. 4 is the push button. FIG. 5 is an exploded perspective view of the keytop holder incorporated in the switch, FIG. 5 is an exploded perspective view of the keytop holder, and FIGS. 6A to 6D are operation explanatory views of the keytop holder.

In these figures, reference numeral 15 is a support plate made of a hard material such as a metal plate, and a membrane switch 16 is mounted on the support plate 15. In this membrane switch 16, a movable contact 18 provided on the lower surface of a flexible upper sheet 17 is made to face a fixed contact 20 provided on the upper surface of a lower sheet 19, and both sheets 17, 1
It is a switch element in which a spacer 21 is provided between 9 parts. Reference numeral 22 is a synthetic resin housing, reference numeral 2
Reference numeral 3 denotes a synthetic resin key top which is held above the housing 22 so as to be able to move up and down. The housing 22 has an opening 22a above the movable contact 18, and
A pair of inward engaging recesses 22b and an outward pair of engaging recesses 22c are provided for slidably engaging engagement protrusions of a keytop holder, which will be described later. And
A well-known click rubber 24 is mounted on the housing 22. The skirt-shaped side wall 24a is formed into a shape that supports the drive portion 24b and is capable of buckling and deforming, and a click feeling is generated when the side wall 24a buckles. The drive portion 24b of the click rubber 24 is located above the movable contact 18.

Reference numeral 25 is a synthetic resin key top holder, and this key top holder 25 has a substantially E-shaped link member 26 and a substantially U-shaped link member 27, as is apparent from FIGS. It is configured by combining. Here, one of the link members 26 has outwardly engaging projections 29a at its tip end portions from both ends of a support shaft 28 for supporting and fixing one side of the back surface of the key top 23, and is directed inward at its substantially central portion. A pair of outer leg pieces 29 having the connecting pins 29b of the pair are extended in parallel, and an operation piece 30 shorter than the outer leg pieces 29 is extended from the center of the support shaft 28. Is an elastic piece having some flexibility against an external force in the plate thickness direction, and when the key top holding body 25 is incorporated into the housing 22, the tip end of the operation piece 30 is the driving portion 24b of the click rubber 24. It always comes in contact with the top surface.
The other link member 27 is inwardly directed toward the tip end in a direction parallel to and intersecting with the outer leg piece 29 from both ends of a support shaft 31 for supporting and fixing the other back surface of the key top 23. Is formed by extending a pair of internal leg pieces 32 each having an engaging projection 32a and a substantially heart-shaped elongated hole 32b in the substantially central portion. A snap using the inclined surface 32c on the upper portion of the elongated hole 32b. The connection pin 29b is loosely inserted into each of the elongated holes 32b by means of an in, and the corresponding outer leg piece 29 and inner leg piece 32 are connected so that the connection pin 29b is movable along the elongated hole 32b. The link members 26 and 27 are integrated to form a key top holding body 25. Therefore, the key-top holding body 25 applies a pressing operation force to the key-top 23 so that both link members 2
When the support shafts 28 and 31 of 6, 27 are pushed in downward, as shown in FIGS. 6A to 6D, the outer leg piece 29 and the inner leg piece that are connected to intersect in a substantially X shape. It is possible to fold both link members 26 and 27 so that the angle at which 32 intersects gradually when viewed from the side of the key top 23 increases, and the height dimension of the key top holding body 25 gradually decreases.

However, the key top holder 25 has a support shaft 28 of an outer link member 26 and a link shaft 2 of the inner link member 2.
The dimension is set so that the inner leg pieces 32 of No. 7 do not come into contact with each other. Specifically, the distance D from the long hole 32b to the support shaft 28 is the length from the long hole 32b to the tip of the inner leg piece 32. L
Is set larger than that (see FIG. 6). Therefore,
Both link members 26 and 27 can be folded until the outer leg piece 29 and the inner leg piece 32 fall to the side.

When the key top holder 25 is attached to the housing 22, the outward engaging protrusions 29a of the outer leg pieces 29 are respectively attached to the inclined surfaces 22 shown in FIG.
Inward engaging recess 2 by snap-in using d
2b, and the inward engaging projections 32a of the respective inner leg pieces 32 are respectively outwardly engaged by snap-in using the inclined surface 22e shown in FIG.
Insert it inside. Thereby, the engagement protrusions 29a, 32a
Are slidably engaged with the engaging recesses 22b and 22c, respectively, and the outer side of each outer leg piece 29 and the inner side of each inner leg piece 32 are positionally regulated by the housing 22. Further, when the key top holder 25 is assembled in the housing 22 in this way, the driving portion 24b of the click rubber 24 previously assembled in the housing 22 makes elastic contact with the tip end portion of the operation piece 30, so that the link is performed via the operation piece 30. Member 26
The support shaft 28 of the link member 2 is urged upward, and the inner link member 2 is connected via the connecting pin 29b of the link member 26.
The support shaft 31 of No. 7 is also biased upward.

As shown in FIG. 1, the housing 22 has a protrusion 22f at a position diagonally opposed to the engaging recess 22b.
Is provided, and the key top holder 25 is attached to the housing 22.
Attached to the engaging projection 29 at the tip of the outer leg piece 29.
Since the rear surface side of a is close to the projection 22f, the engagement protrusion 29a is not easily disengaged from the engagement recess 22b even when a strong external force such as impact is applied.

The push button switch constructed as described above is
The support shafts 28 and 31 of the link members 26 and 27 of the key top holder 25 receive the elastic force of the click rubber 24 to support both sides of the back surface of the key top 23. Since the outer leg pieces 29 and the inner leg pieces 32 of 26 and 27 are connected so that the angle at which they intersect can be changed, and the position of each leg piece 29 and 32 is regulated by the housing 22, After all, the key top 23 is held above the housing 22 so as to be able to move up and down.

Therefore, when the operator applies a pressing operation force to the key top 23 and pushes both support shafts 28 and 31 against the elastic force of the click rubber 24, both support shafts 28 and 31 are pushed.
Rotates on the spot, and each engaging protrusion 29a, 32a
Slides in the engagement recesses 22b and 22c, and is connected to intersect the substantially X-shaped outer leg piece 29 and the inner leg piece 3.
2 gradually increases the angle of intersection as viewed from the key top 23 side, and the operating piece 30 pushes the drive portion 24b of the click rubber 24 downwards accordingly, so that the drive portion 24
When b is lowered by a predetermined amount, the side wall portion 24a buckles and a click feeling is generated, and the driving portion 24b is pushed forcefully to collide with the upper sheet 17 of the membrane switch 16, and as a result, The upper sheet 17 bends downward and the movable contact 18 comes into contact with the fixed contact 20, and switching from the off state shown in FIG. 2 to the on state shown in FIG. 3 is performed.

When the operator removes the pressing operation force on the key top 23 in this ON state, the buckled click rubber 24 returns to its original shape by its own elasticity, so that the driving portion 24b rises. The operation piece 30 is pushed up by the user and the two link members 2 are folded.
6, 27 stand up, the key top 23 is pushed up to the initial position, the bending of the upper sheet 17 is eliminated, the movable contact 18 is separated from the fixed contact 20, and the state returns to the off state.

As described above, in the above embodiment, the link member 2
Both link members 26 that support the key top 23 using a key top holding body 25 that is a combination of 6, 27 and that can change the crossing angle according to the height position of the key top 23,
Since the position of each leg piece 29, 32 of 27 is regulated by the housing 22, the key top 23 can be moved straight up and down without a guide wall like the conventional product standing upright on the housing 22. The parts that hinder the lifting and lowering operation of the device 23 are less likely to be caught by each other. Therefore, the push button switch can be significantly thinned without impairing the operability and reliability.

Further, in the above embodiment, the dimension is set so that the tips of the inner leg pieces 32 of the inner link member 27 do not contact the support shaft 28 of the outer link member 26.
As shown in FIG. 6 (d), both link members 26, 27 can be folded until they fall to the side, and therefore, there is an advantage that the stroke lowest point of the key top 23 can be set to an extremely low position. This is convenient for promoting thinning.

Further, the key top holding body 25 used in the above embodiment has the leg pieces 29 and 32 of the link members 26 and 27.
By making the connecting pin 29b slidable along the long hole 32b at the intersecting part of and the engaging projections 29a, 32a of the tip ends of the leg pieces 29, 32 slidable with respect to the housing 22, Since the link members 26 and 27 can be folded while keeping the distance between the two support shafts 28 and 31 located on the base end side of the leg pieces 29 and 32 constant, both the key tops 23 are supported. A support structure for fixing the shafts 28 and 31 is realized. That is, for example, both link members 2 with the intersection of each leg 29, 32 as the center of rotation.
6, 27 can be folded, but in that case, a support structure in which the key top 23 is slidable with respect to both link members 26, 27 must be adopted, and the shape of the back surface of the key top 23 is complicated. It may become larger or larger.
However, if both link members 26 and 27 can be folded without laterally shifting the base end portions of the leg pieces 29 and 32 as in this embodiment, the key top 23 can simply support shafts 28 and 31.
As shown in FIGS. 2 and 3, the shape of the back surface of the key top 23 is simple and small, so that it has good moldability and is suitable for thinning. Since the key top 23 can be attached to the key top holder 25 by snap-in, it is easy to assemble.

In addition, the key top holder 25 used in the above embodiment has the outward engaging projections 29a of the outer leg pieces 29.
Are engaged with the inward engaging recesses 22b of the housing 22, respectively, and the inward engaging protrusions 32 of the respective inner leg pieces 32 are engaged.
a is an outward engaging recess 22c of the housing 22
The position of each leg piece 29, 32 and by extension both link members 26, 27 can be regulated by the housing 22 by engaging with the outer leg piece 29 and the inner leg piece 32 connecting the intersections. The position is always regulated from the separating direction. Therefore, the connection between the two leg pieces 29 and 32 is guaranteed, and even if a strong external force is applied, the engagement protrusions 29a and 32a are unlikely to be disengaged from the corresponding engagement recesses 22b and 22c, and the housing of the keytop holder 25 is provided. The accident of dropping from 22 has been prevented.

Furthermore, in the key top holder 25 used in the above embodiment, one link member 26 is provided with an operating piece 30.
Is provided, and when the operator pushes in the key top 23, the operation piece 30 pushes and drives the movable contact 18 via the drive portion 24b of the click rubber 24. Therefore, the stem can be omitted, and the amount of lowering of the drive portion 24b required for switching can be set smaller than the operation stroke of the key top 23. That is, the link member 26 having the operation piece 30 rotates about the tip of the external leg piece 29 as a movable fulcrum, but the turning radius of the tip of the operation piece 30 elastically contacting the top surface of the drive portion 24b is: Since it is about half the turning radius of the support shaft 28 that is directly pushed into the key top 23, the drive portion 24b
The pressing amount of the key top 23 can be about half the pressing amount of the key top 23. As a result, the deformation amount of the click rubber 24 due to the operation is reduced, the life thereof is extended, and high reliability can be maintained for a long time. .. Further, since the turning radius of the tip end portion of the operation piece 30, which is the point of action, is about half the turning radius of the support shaft 28, which is the force point, the lever principle
Even if the pressing operation force applied to the support shaft 28 is small, the click rubber 24 can be pushed in with a large force through the operation piece 30, and thus there is an advantage that the pressing operation force can be reduced. In addition, in the above embodiment, the operation piece 30 itself is an elastic piece, and the operation piece 30 is slightly bent after the driving portion 24b of the click rubber 24 is pushed to the lowest point of the stroke, so that the operation piece 30 is an extremely thin push button switch. However, it is possible to reliably obtain an overstroke and expect a good feeling of operation.

In the above embodiment, the operation piece provided on the outer link member is elastically contacted with the click rubber, but a similar operation piece is provided on the inner link member, or an elastic member other than the click rubber is used. The link member may be biased upward, or an operation piece that can directly press and drive the movable contact without using an elastic member may be adopted. Needless to say, the connecting structure of both link members, the supporting structure for the key top, the engaging structure for the housing, and the like can be appropriately selected.

[0025]

As described above, the outer leg piece and the inner leg piece of both link members connected so that the crossing angle can be changed according to the height position of the key top are positioned by the housing from the separating direction. According to the present invention of restricting, it is not necessary to erect the guide wall on the housing, and the push button switch can be significantly thinned without hindering the raising / lowering operation of the key top, and further, The connection between the outer leg piece and the inner leg piece is guaranteed, and the two link members can be prevented from falling off the housing.
High reliability can be maintained even when a strong external force is applied.

[Brief description of drawings]

FIG. 1 is a plan view showing an internal structure of a push button switch according to an embodiment.

FIG. 2 is a sectional view of the push button switch in an off state.

FIG. 3 is a sectional view of the push button switch in an ON state.

FIG. 4 is a perspective view of a keytop holder incorporated in the push button switch.

FIG. 5 is an exploded perspective view of the key top holder.

FIG. 6 is an operation explanatory view of the keytop holder.

FIG. 7 is a cross-sectional view showing a conventional push button switch.

[Explanation of symbols]

 16 Membrane Switch (Switch Element) 18 Movable Contact 20 Fixed Contact 22 Housing 22b, 22c Engagement Recess 23 Key Top 24 Click Rubber (Elastic Member) 25 Key Top Holder 26 (First) Link Member 27 (Second) ) Link member 28 Support shaft (first support portion) 29 External leg piece 29a Engagement protrusion 29b Connecting pin (intersection portion) 30 Operation piece 31 Support shaft (second support portion) 32 Internal leg piece 32a Engagement protrusion 32b Long hole (intersection)

Claims (3)

[Claims] 1. A key top held up and down freely above a housing, an elastic member arranged below the key top and biasing the key top upward, and a movable contact facing a fixed contact. A push button switch including a switch element, wherein the movable contact comes into contact with the fixed contact to perform switching by pushing the key top against the elastic member, and an outwardly protruding engagement protrusion is provided at a tip end portion of the push button switch. And a pair of external legs extending in parallel with each other, a first link member having a shape in which a first supporting portion for supporting one side of the back surface of the key top is bridged, and an inward engaging projection at a tip portion. A pair of inner legs extending parallel to the outer leg and extending in a direction intersecting the inner leg with a second support portion for supporting the other back side of the key top. With two link members , The outer leg piece and the inner leg piece are connected at their intersections so that the angle at which they cross each other can be changed, and both of these link members are urged upward by the elastic member and the housing A pair of inward engaging recesses that allow the engagement protrusions of the outer leg pieces to be loosely inserted and engage, and a pair of outer recesses that allow the engagement protrusions of the inner leg piece to be loosely inserted and engaged. A push button switch characterized by being provided with an engaging recess for orientation. 2. The method according to claim 1, wherein at least one of the first and second link members comprises:
A push button switch comprising an operation piece capable of pressing and driving the movable contact. 3. The push button switch according to claim 2, wherein the operation piece is elastically contacted with the elastic member.