GB2108323A

GB2108323A - Push-button switch

Info

Publication number: GB2108323A
Application number: GB08230479A
Authority: GB
Inventors: Isao Ito
Original assignee: Alps Electric Co Ltd
Current assignee: Alps Alpine Co Ltd
Priority date: 1981-10-28
Filing date: 1982-10-26
Publication date: 1983-05-11
Also published as: GB2108323B; DE3231918C2; JPS6033538Y2; DE3231918A1; JPS5865722U

Abstract

A push-button switch has a casing (10), a hollow stem (11) slidably mounted in a hole (10a) in the casing, and a key top (12) attached to the stem (11). The hollow stem (11) has a pair of opposing inner walls (11b) provided with lugs (11e). The key top (12) has a projection (12c) with hollows (12c) whereby the key top (12) and the stem (11) can be firmly interlocked by the action of the lugs and hollows. Any bending of the inner walls during interlocking is permitted by interspaces defined between the inner walls (11b) and the outer peripheral wall (11a) of the stem (11). <IMAGE>

Description

SPECIFICATION Push-button switch The present invention relates to a push-button switch. More particularly, the present invention relates to a thin push-button switch having good sliding operation.

Heretofore, a push-button switch of the type of the present invention has had a construction as shown in Figure 1. A box-shaped casing 1 is made of an insulative material and receives a stem-resetting spring, a switching mechanism, etc. (not shown). A prismatic stem 2 is movably inserted in an opening la of the casing 1, and the upper end of this stem 2 is press fitted into a cylindrical portion 3a of a key top 3, thereby to mount the key top 3 on the stem 2. The switch is actuated by depressing the key top 3 to move the stem 2 downwardly and then released to return the kep top 3 by the action of the stem -resetting spring as the stem 2 slides within the la opening of the casing 1 as its guide.

In the prior art, however, the key top 3 and the stem 2 are typically attached by press fitting the cylindrical portion 3a of the former on the outer perhiphery of the upper end of the latter, and hence, the stem 2 often requires a tubular part 2a for attaching the key top 3. This tubular part, however, protrudes outward beyond the sliding stroke of the stem 2 relative to the hole 1 a. This leads to the disadvantage that the push-button switch is enlarged in the vertical direction and its thickness cannot be made very thin. Moreover, the tubular part 2a for attaching the key top 3 needs to be made rather long in order to firmly mount the key top 3, which makes it further difficult to reduce the thickness of the push-button switch.Besides, the stem 2 is ordinarily formed into the shape of a comparatively slender prism in order to make the size of the push-button switch small, so that the cross-sectional area of the stem 2 is rather small. This leads to the disadvantage that, when the key top 3 is depressed obliquely in the direction of arrow A or arrow B in Figure 1, the sliding operation of the stem 2 as well as the feel of the operation becomes inferior.

According to the invention, there is provided a push-button switch comprising a casing having a switching mechanism, a stem slidably mounted in a hole in said casing for operating the switching mechanism, said stem being formed by an outer peripheral wall, inner walls formed within said peripheral walls and adapted to define interspace portion separated by a central hollow, a key top having a protuberance arranged to fit within said hollow and engaging means provided in at least one of said inner walls of said stem and said protuberance of said key top, whereby said inner walls may be deformed in said interspaces and thereafter be resiiiently restored as said stem is inserted into said hollow to unitarily couple said key top and said stem through said engaging means.

According to the invention, there is further provided a push-button switch comprising a housing, a hollow stem slidable supported in an opening in said housing, a pair of resiliently displaceable walls located within the hollow of said stem, a push-button having a projection, engagement of said projection with said walls effecting displacement of the walls and detent means for locking said projection to said stem when the projection reaches a predetermined disposition relative to the said walls.

Push-button switches embodying the invention will now be described, by way of example, with reference to the accompanying diagrammatic drawings in which: Figure 1 is a part-sectional view of a prior-art push-button switch; Figure 2 is a sectional view of one of the push-buttons switches embodying the invention; Figure 3 is a perspective view, partly broken away, of the push-button switch of figure 2 with its key top removed therefrom; and Figure 4 is a perspective view, partiy broken away, of another one of the switches embodying the invention.

A push-button switch comprises a casing receiving a switching mechanism; and stem is slidably mounted in a hole of the casing to operate a switching mechanism. A key top having a protuberance is mounted on the stem; and the stem is formed by an outer peripheral wall; inner walls formed integrally with the outer peripheral wall, and interspaces which are defined between the outer peripheral wall and the inner walls. These interspaces allow the inner walls to deform without effecting the outer peripheral walls, A hollow adjoins the interspaces and the protuberance of said key top is snugly fitted within this hollow.Engaging means are provided on eitherthe inner walls of said stem or the protuberance of said key top, or both, and the inner walls may bend and thereafter be elastically restored to unitarily couple the key top and the stem through the engaging means when said protuberance of the key top is inserted into the hollow of the stem.

Numeral 10 designates a box-shaped casing made of an insulator and receiving a stem resetting spring, a switching mechanism, etc. (not shown). Symbol 10a denotes a rectangular opening which is provided in the casing 10. Numeral 11 indicates a stem made of an insulative material such as a polyacetal resin which is movably mounted in the opening 10a of the casing 10. The stem 11 is generally in the shape of a hollow prism and is made much larger than comparable stems of the prior art.The stem comprises an outer peripheral wall 1 lea, a pair of inner walls 11 b which are formed inside the outer peripheral wall Ila, interspaces defined between the end portions of the outer peripheral wall 1 lea and the inner walls 11 b, a hollow 1 formed centrally of the stem 11 and surrounded by the pair of inner walls 11 band the outer peripheral wall 11 a.

Lugs 1 1e are provided on the inner surfaces of the pair of inner walls 11 bin a manner so as to extend toward the hollow 11 d. By forming the stem 11 by the pair of inner walls 11 b, the interspaces 11 C and the hollow 11 d, the stem can be made rather large and broad.

Numeral 12 indicates a key top of an insulative material such as ABS resin. The key top 12 compris es a depression surface 12a, and a protuberance 12c provided centrally of the lower surface 12b iying opposite the depression surface 12a. The protuberance 12e of the key top is formed in a size approximately equal to that of the hollow 1 idofthe stem 11.

In mounting the key top 12 on the stem 11, the protuberance 12e of the key top 12 is first inserted into the hollow 1 ldofthe stem 11 until the protuberance 1 2c abuts against the lugs 11 on the inner walls lib. Subsequently, when the key top 12 is further pushed in, the inner walls 11 b bend outwardly owing to the adjacent interspaces 11 c, and onto these interspaces 11c.The upper end of the stem 11 may then be moved against the lower surface 1 2b of the key top 12, with the lugs 1 1 e of the stem 11 sinking into the protuberance 12cofth a key top 12.

Even when, in mounting the key top 12 -ae inner walls 11 bare in the bent state due to Th tight fit between the protuberance 12e and the lugs 11e,the bending can be absorbed by the interspaces 11 c, so that any influence on the outer peripheral wall 11 a performing the sliding operation relative to the hole 1 ova can be avoided. In addition, when spaces 11 fare provided between the outer peripheral wall 11a and the sides of the inner walls 11 ib, as illustrated in Figure 4, the influence of the bending of the inner walls 11 b on the outer peripheral wall 11 a can be improved still more.

Now, in the push-button switch constructed as described above, when the depression surface 1 2a of the key top is depressed against the stem resetting spring (not shown}, the stem 11 moves downward while sliding with the hole 10a of the casing 10 acting as a guide.

On the other hand, when the depression is re leased, the stem 11 as well as the key top 12 is restored to the original position by the stem resetting spring. Since, by this invention, the protuberance i2cofthe key top 12 lies within the outer peripheral wall 11 a of the stem 11, the part of the stem 11 up to the height near the upper end thereof can be utilized as a sliding area. Moreover, since the stem 11 is massive and broad, the supporting area of the stem 11 by the hole 1 Oa, so that the stem 11 slides well even when the key top 12 is depressed obliquely in the direction of arrow A or B in Figure 2.

The protuberance 12e of the key top 12 is inserted into the hollow lid provided in the outer peripheral wall 1 a 1a of the stem 11 so as to coulplethe key top 12 and the stem 11. Therefore, the outwardly protruding part 2a of the stern 2 for mounting the key top 3 in the prior art is dispensed with, and the switch may be made thinner in the vertical direction.

Besides, the stem 11 is provided with the interspaces 11 C between the inner walls 11 band the outer peripheral wall 11 a, so as to absorb by these interspaces licanydeformation of the innerwalls 11 b as the protuberance 12e of the key top 12 is inserted in the hollow 11 d of the stem. Therefore, the influence of the bending on the outer peripheral wall 11 a can be eliminated, and the stem 11 can be made to slide rather smoothly. Moreover, owing to the above-stated construction, the stem 11 can be made massive and broad as a whole, and the supporting area of the stem 11 in the hole 10a of the casing 10 can be made large, to further enhance the sliding operation of the stem 11. Furthermore, the protuberance 12e of the key top 12 is held in fitted engagement with the lugs lie of the stem 11. Therefore, the mounting of the key top 12 is rigid, while any influence of the bending of the inner walls ii b on the outer peripheral wall 11 a can be avoided because the lugs lie are provided on the inner wails 11 b of the stem 11. In the foregoing embodiments, the lugs may, of course, be provided on the protuberance 12c or lugs may be provided on both the protuberance l2candthe innerwalls lib.

Claims

1. A push-button switch comprising a casing having a switching mechanism, a stem slidably mounted in a hole in said casing for operating the switching mechanism, said stem being formed by an outer peripheral wall, inner walls formed within said peripheral walls and adapted to define interspace portions separated by a central hollow, a key top having a protuberance arranged to fit within said hollow, and engaging means provided in at least one of said inner walls of said stem and said protuberance of said key top, whereby said inner walls may be deformed in said interspaces and thereafter be resiliently restored as said stern is inserted into said hollow to unitarily couple said key top and said stem through said engaging means.

2. A push-button switch according to claim 1, wherein said inner walls are formed by a pair of walls confronting each other, said engaging means are provided in the respective inner walls and on the sides of said protuberance.

3. A push-button switch according to claim 2, wherein said engaging means formed on said inner walls are constituted by lugs confronting each other.

4. A push-button switch according to any one of claims 1 to 3, including slits provided between said inner walls and said outer peripheral wall.

5. A push-button switch according to any preceding claim, said stem having a sliding area relative to said casing extending nearly to its upper end.

6. A push-button switch comprising a housing, a hollow stem slidably supported in an opening in said housing, a pair of resiliently displaceable walls located within the hollow of said stem, a push-button having a projection, engagement of said projection with said walls effecting displacement of the walls and detent means for locking said projection to said stem when the projection reaches a predetermined disposition relative to the said walls.

7. A switch according to claim 6, wherein said detent means comprises a pair of lugs projecting from the facing surfaces of respective ones of said walls and a pair of mating recesses in said projection.

8. A push-button switch substantially as hereinb efore described with reference to the Figures 2 and 3 of the accompanying drawing.

9. A push-button switch substantially as hereinb efore described with reference to the Figure 4 of the accompanying drawing.