GB2261769A

GB2261769A - Switch

Info

Publication number: GB2261769A
Application number: GB9216281A
Authority: GB
Inventors: Ming-Yuan Kuo
Original assignee: Silitek Corp
Current assignee: Silitek Corp
Priority date: 1991-11-21
Filing date: 1992-07-31
Publication date: 1993-05-26
Anticipated expiration: 2012-07-31
Also published as: CN2139301Y; GB2261769B; DE9201284U1; GB9216281D0

Abstract

A switch comprises a switching key 1, an elastic rubber base 2 attached to the peripheral edge of the switching key 1 by a melting process, and a conductive rubber contact 3 fixed to the bottom of the switching key 1. The switch is formed by placing a solid plastics switching key 1 and a rubber sheet between a pair of dies and melting the rubber sheet to cause the rubber to flow into at least one groove in the bottom surface of the switching key 1 and form the elastic rubber base 2 with a sloping portion 200 between the switching key 1 and the elastic rubber base 2 for returning the switching key back to its original position after each press. <IMAGE>

Description

KEY SWITCH BACKGROUND OF THE INVENTION The present invention relates to key switches and relates more particularly to a key .switch formed of a rigid plastic key welded to an elastic rubber base and attached with a conductor rubber for switching operation.

Key switches have been commonly used in computer systems, telecommunication equipment, telephones, alztO cashier machines, auto teller machines, keyboard controlled door locks, ... and etc., for data input. From mechanical to membrane type, several structures of key switches have been known.

Conventionally, a key switch is comprised of a plastic cap supported on a spring or an elastomer. When the plastic cap is pressed on, a conductor rubber is moved to connect a circuit. Once the external pressure is released, the plastic cap is immediately pushed by the spring or elastomer to return to its original position.

Because the plastic cap and the spring (or elastomer) are separately made, the assembly process of a key switch becomes complicated. Complicated assembly process simultaneously increases the cost of a key switch. Further, error contact problem may happen easily because gap exists between the plastic cap and the spring (or elastomer).

SUMMARY OF THE INVENTION The present invention has been accomplished to eliminate the aforesaid problems. It is therefore an object of the present invention to provide a kev switch which is practical and durable in use. It is another object of the present invention to provide a key switch which is easy and inexpensive to manufacture.

The main feature of the present invention is to attach a rigid plastic key to an elastic rubber base through the process of melting. By means of this arrangement, the manufacturing process of a key switch becomes easy.

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of key switches embodying the present invention; Fig. 2 is an exploded perspective view of the upper and lower dies according to the present invention, in which the internal structure of the lower die is shown; Fig. 3 is another exploded perspective view of the upper and lower dies according to the present invention, in which the internal structure of the upper die is shown; Fig. 4 is a side sectional view of Fig. 1; Figs. 5-A and S-B illustrate the positioning of the present invention before and after each press; and Fig. 6 illustrates an alternate form of the present invention showing the positioning of the key switches before and after each press.

DETAILED DESCRIPTION OF THE PREERRED EMBCOIMENTS Referring to Fgs. 1 through 5, a key switch as constructed in accordance with the present invention is generally comprised of a switching key 1, a rubber base, and a conductor rubber'3.

As illustrated in Fig. 2, a switching key 1 is made from a solid, rigid plastic, having an annular grooye 10 on the bottom edge thereof around the periphery, a plurality of binding grooves 11 through the bottom edge thereof, and a raised portion 12 on the.

bottom edge thereof at the center for attaching a conductor rubber 3. The switching key 1 is connected to a rubber base 2 through the process of melting performed in an upper die 20 and a lower die 21.

Referring to Fig. 2 again, a lower die 21 has four locating holes 212 at the four corners thereof a rectangular recess 210 and a plurality of recessed holes 211 on said rectangular recess 210 for inserting a switching key 1 each. Each recessed hole 211 on the rectangular recess 270 of the lower die 21 has a chamfered edge 2130 around the orifice thereof.

Referring to Fig. 3, an upper die 20 has four unitarv bolts 203 at the four corners thereof respectively inserted into the four locating holes 212 on the lower die 21 for positioning, a rectangular recess 202 corresponding to the rectangular recess 210 on the lower die 21, and a pluralty of flanges 201 raised on the rectangular recess 202 thereof at locations and in size corresponding, to the recessed holes 211 on the lower die 21. When a switching key 1 is inserted in each recessed hole 231, a rubber sheet is placed in the rectangular recess 21.0, then, the upper die 20 is secured to the lower die 21 to firmly retain the rubber sheet in place.Because rubber and plastic materials have different melting point, the rubber sheet can be easily melted, through temperature control, to fill in the grooves 1.0, 1.1 on each switching key 1 and the space defined within the re.ctangular re.cesses 210, 202, while the shape of each switching key 1 remains unchanged.

After setting, an elastic rubber base 2 is formed with a plurality of switching keys t unitarily secured thereto.

Once the elastic rubber base 2 is removed from the upper and lower dies 20, 21, a plurality of key switches are made. Referring to Fig. 4, by means of the arrangement of the chamfered edge 2110 on each recessed hole 211, a sloping edge 200 is formed between the.

connecting areas of the elastic rubber base 2 and each key switch thereon. This sloping edge 200 makes each switching key 1 to be automatically moved back to its original position after each press.

conductor rubber 3 may be made on the raised portion 12 on each switching key l through the process of printing, or directly connected to the raised portion J2 on each switching key 1 during the me3t:ing process in forming an elastic rubber base 2.

Referring to Figs. 5A and 5R, the conductor rubber 3 on the raised portion 12 of a switching key 1 is spaced above the bottom edge of the elastic rubber base 2 which is mounted on a PC board 4 at the top.

When the switching key t is pressed on, the conductor rubber 3 is moved to electrically contact the corresponding circuit on the PC board 4. Once the external pressure is released from the switching key 1, the elastic material property of. the sloping edge 200 automatically moves the switching key 1 back to its original position so as to disconnect the conductor rubber 3 from the PC board 4.

Referring to Fig. 6, the shape of the connecting area between each switching key 1 and the elastic rubber base 2 may be variously embodied by changing-the shapes of the grooves on each switching key 1.

As indicated, the present invention is to provide a key switch whi.ch is comprised of an elastic rubber base and a switching key unitarily incorporated together through the process of melting. By means of the process of melting, a key switch is inexpensive to manufacture, practical and durable in use.

Claims

CLAIMS:

1. A key switch1 the improvement comprising a switching key having at least one groove on the bottom edge thereof into which rubber fluid can be filled; an elastic rubber base connected to a peripheral bottom edge on said switching key through the process of melting; a conductor rubber adhered. to said switching key at the bottom and moved by said switching Rey through a hole on said elastic rubber base to connect a circuit beneath said elastic rubber base.

2. The. key switch or claim 1, wherein switching ky is adhered to said elastic rubber base through the process of melting under a temperature above the melting point of. said elastic rubber base and below the melting pojnt of said switching key.

3. The key switch of claim 1, wherein said conductor switch is made on said switching key through the process of printing.

4. The key switch of claim I, wherein said conductor switch is adhered to said switching key through the process of melting.

5. A key switch substantially as hereibefore de scribed with reference to, and as illustrated in, Figs. 1 to 5; or Fig. 6; of the accompanying drawings.