EP0398186A2

EP0398186A2 - Keyboard unit

Info

Publication number: EP0398186A2
Application number: EP90108929A
Authority: EP
Inventors: Koichi C/O Omron Corporation Hyakutake
Original assignee: Omron Corp; Omron Tateisi Electronics Co
Current assignee: Omron Corp
Priority date: 1989-05-16
Filing date: 1990-05-11
Publication date: 1990-11-22
Also published as: JPH02146725U; EP0398186A3

Abstract

A keyboard unit according to this invention is comprised of a base plate with contacts, a soft rubber seat covering almost all of the base plate and having a raised portion forming a space between the base plate contacts and corresponding rubber seat contacts, and a hard rubber key provided on the raised portion of the soft rubber seat and projecting upwardly, wherein the soft rubber seat and hard rubber key are integrally formed.

Description

BACKGROUND OF THE INVENTION:

Field of the Invention

This invention relates to a keyboard unit used as a data inputting device in a peripheral system.

Related Art:

Hitherto, two types of conventional keyboard units have been utilized as an inputting device. Both types comprise a plurality of keys with a contact on the bottom side thereof for contacting two contacts on a base plate to complete a circuit and initiate a current flow indicating key depression. Additionally, each contact of both types is surrounded by a rubber seat. However, the first type is comprised of keys made of two parts, wherein the bottom part is made of soft rubber while the top of the key is made of a hard rubber. The second type of conventional keyboard unit, on the other hand, is comprised of keys that are make entirely with soft rubber. Furthermore, this second type of key has a concave inner portion.
Both conventional types of keys have problems. First, both types are expensive to produce because numerous man hours are needed to assemble the rubber seats in proper positions. The first type has an additional cost resulting from forming each key in two steps, with the soft rubber portion on the bottom and the hard rubber portion on top. While the second type of key is formed in one step with soft rubber, performance is low because the soft rubber does not provide good tactile feedback informing an operator that a key has been depressed.

SUMMARY OF THE INVENTION:

Accordingly, the object of the invention is to provide a keyboard unit that is less expensive to produce and provides a higher tactile feedback than conventional keyboard units.
This object is realized by providing a rubber seat that covers roughly the whole surface area of the base plate as opposed to the ring-shaped rubber seats of the prior art. The rubber seat according to this invention is made of soft rubber and, furthermore, is raised at each base contact area. Keys are formed by molding a hard rubber top onto the raised portions of the rubber seat, utilizing an injection process.
Thus, the keys are integrally formed in one step and, due to the hard, unforgiving top, provide sufficient tactile feedback for an operator.
Other objects and advantages of this invention will become apparent from the following description and accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS:

Fig. 1 is a slant view of a keyboard unit according to this invention.
Fig. 2 shows an exploded perspective view of the keyboard unit according to this invention.
Fig. 3 is a cross-sectional view of a key on the keyboard unit according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT:

As shown in Fig. 1, a keyboard unit 1 according to this invention has a base plate 5, a rubber seat 6, rubber keys 7 with a hard rubber material 8 on top, a lattice-shaped frame 9, a cable 10, a socket 11 with sockets pins 15, and fixing studs 13.
Turning to Fig. 2, the base plate 5 has a plurality of screw assembly holes 2, socket connection holes 3, and cable terminal connection holes 4 for connecting a cable terminal 16 to the base plate 5. In addition, a printed wiring pattern is etched on the base plate 5 (not shown). The rubber keys are integrally formed by the rubber seat 6 on the bottom and the hard rubber material 8 on top. The lattice-shaped frame 9 is used to fix the hard rubber to the base plate 5. The cable 10 is necessary to connect the keyboard unit 1 to a main apparatus (not shown). The socket pins 15 go through the socket connection holes 3 and the cable terminal 16 goes through the cable terminal connection holes 4.
Corresponding to the screw assembly holes2 of the base plate 5 are screws 14 for securing the rubber seat 6. Specifically, screws 14 go through the holes 2 and fix the rubber seat 6 by projecting past U-shaped cut-out portions 12 of the rubber seat 6 and engaging with screw holes 24 on the bottom side of the lattice-shaped frame 9. Thus, the base plate 5, the rubber seat 6, and the lattice-shaped frame 9 are all connected by the screws 14.
Fig. 3 shows the internal key 7 construction of this invention. Base plate contacts 17 are located in designated positions on the upper side of the base plate 5. Over the base plate contacts 17 is a concave-shaped raised portion 6a of the rubber seat 6. Between the raised portion 6a and the upper side of base plate 5 is a space 18 that is surrounded by the rubber seat 6. Furthermore, a flat bottom portion 6b is located on the bottom of raised portion 6a and is parallel to the base plate 5. Located on the surface of the flat portion 6b is a key contact 19. When the key 7 is depressed, an elastic portion 6c bends and the key contact 19 is downwardly displaced through space 18 and contacts the base plate contacts 17. When this happens, the circuit is completed and electricity flows through the base plate contacts 17 to signal key depression and corresponding data is input into peripheral system.
After the contacts 17,19 break contact, the key 7 returns to its normal position, providing good tactile feedback to inform the operator that the key was depressed. Finally, preferred rubber for both the soft, rubber seat 6 portion and the hard, top portion 8 of the key is silicon rubber because silicon rubber has good heat resistance as it is chemically combined with a backbone chain of silicon and oxygen.
The above descriptions and accompanying drawings are merely illustrative of the applications of the principles of the present invention and are not limiting. Many other embodiments falling under the spirit and scope of this invention may be devised by those skilled in the art. Accordingly, this invention is only limited by the scope of the appended claims.

Claims

1. A keyboard unit, comprising:
a base plate equipped with a plurality of contacts;
a rubber seat covering roughly the whole surface of the base plate, wherein said rubber seat has a raised portion forming a space between said base plate contacts and corresponding rubber seat contacts;
a rubber key provided on said raised portion of the rubber seat and projecting upwardly; and
said rubber seat is comprised of a soft rubber material and said rubber key is comprised of a hard rubber material, wherein the rubber seat and rubber key are integrally formed.