Electricity: circuit makers and breakers – Multiple circuit control – Multiple switch
Patent
1986-02-13
1987-12-01
Scott, J. R.
Electricity: circuit makers and breakers
Multiple circuit control
Multiple switch
200159B, 200314, 200340, 235145R, H01H 1370
Patent
active
047105976
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to a keyboard for a control box of an electric apparatus.
2. Description of Pertinent Information
Traditional keyboards for control boxes of electrical apparatuses such as calculators and telephones generally comprise plastic bearing keys provided with metallic contact pads which act on a printed circuit.
The keys of these traditional keyboards are biased in their resting position out of contact with the printed circuit by springs.
As these keyboards evolved, the springs were eliminated by using a sheet of contactors made of non-conducting silicone, each contactor projecting from the sheet through a blister forming a spring. The metallic pads were then advantageously replaced with pads made of conducting silicone.
In these apparatuses, the plastic keys are guided by and rest upon the contactors.
Other types of keyboards were also developed in which the keys are directly molded with the sheet of contactors. In these keyboards the keys are also made of silicone.
Both types of keyboards suffer from disadvantages. One of the disadvantages of the apparatuses in which the keys are separate from the sheet of contactors, resides in the need and difficulty in assembling these separate elements in the box, whereas the keyboards are generally made and delivered separately.
The apparatuses in which the silicone keys are integrally formed with the sheet of contactors have, on the other hand, the disadvantage of reducing disposable space under the sheet.
If to remedy this situation, the interior of the keys are hollowed out to gain space, they then risk not being sufficiently rigid, particularly when the keys are provided with several contact pads.
Finally, it is impossible, with both types of keyboards, to light the keyboard with luminescent diodes without resorting to complicated or cumbersome apparatuses using double printed circuits, for example.
SUMMARY OF THE INVENTION
It is an object of the present invention to solve these problems by separating the bearing keys from the sheet of contactors but in an original way so as to produce a complete keyboard ready for use.
The keyboard according to the invention comprises a sheet which forms a plurality of contactors each projecting from the sheet by means of a blister which is elastically deformable and which acts as a spring. The contactors are also provided with bearing keys and contact pads adapted to come into contact with a printed circuit, arranged under the sheet of contactors, when a pressure is exerted on the keys. This keyboard is remarkable in that at least some of the contactors have stubs arranged opposite from the contact pads which are adapted to be force nested into corresponding housings provided in the bearing keys.
Advantageously, for reasons which will be seen later, the sheet of contactors has projections adapted to rest on the printed circuit in such a manner to create a space between the latter and the sheet of contactors.
In this case, the projections are preferably arranged around displacement axes of the contact pads.
In the embodiment using the separation projections mentioned earlier, the sheet of contactors is traversed by one or several luminescent diodes positioned between the contactors and under or between the keys while the sheet of contactors and the keys have a free space between them and the box in such a manner so as to permit the light of the diodes to be diffused in this space after having been diffused in the space between the printed circuit and the sheet of contactors.
It is within the scope of the invention for the bearing keys to be formed individually or together in any material such as plastic, or any other material.
According to a particularly interesting embodiment the bearing keys are formed from a block in a sheet of keys which covers the sheet of contactors. In this embodiment each key projects from the sheet of keys by means of a supple blister which covers one or several of the elastically deformable blisters of the sheet of contactors.
Th
REFERENCES:
patent: 3823309 (1974-07-01), Caruso
patent: 4066860 (1978-01-01), Kawasaki
patent: 4163138 (1979-07-01), Harden
patent: 4203013 (1980-05-01), Serras-Paulet
patent: 4311893 (1982-01-01), Tsuchiya et al.
patent: 4386245 (1983-05-01), Nimura et al.
patent: 4471189 (1984-09-01), Bacon et al.
Scott J. R.
Tabur Caoutchouc
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