US 4,864,085 AGranted

Keyboard switch

AssigneeHosiden Electronics Co., Ltd.

InventorsTadashi Hanajima, Tatsuo Kato

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Abstract

A membrane switch sheet is disposed on a base plate and an adhesive layer is formed all over the membrane switch sheet. A positioning sheet, which has positioning holes respectively corresponding to membrane switches arranged on the membrane switch sheet, is disposed on the adhesive layer, and a tact plate having a normally upward curved portion is bonded to the adhesive layer in each positioning hole. A mounting plate is disposed on the positioning sheet at a distance therefrom. The mounting plate has a sleeve at a position corresponding to each tact plate. A stem is slidably received in the sleeve. The stem is capped with a key top formed integrally therewith. An acutating coiled spring is fixed at one end and engaged at the other end with the tact plate. When the key top is depressed, the coiled spring presses down the corresponding membrane switch through the tact plate, turning on the switch. At the same time, the curved portion of the tact plate is flexed downward, producing a click-like touch in response to the keying operation.

Claims7

Dependent claims

A keyboard switch comprising:

a base plate;
a membrane switch sheet having arranged therein a plurality of membrane switches and disposed on the base plate;
an adhesive layer provided all over the membrane switch sheet;
a positioning sheet disposed on the adhesive layer and having positioning holes respectively corresponding to the plurality of membrane switches arranged on the membrane switch sheet;
a resilient tact plate disposed on the adhesive layer and positioned in each positioning hole, the tact plate having a normally upwardly curved portion which can be flexed downward by an external force;
a mounting plate disposed in adjacent but spaced relation to the positioning sheet and fixed to the base plate;
at least one guide portion formed integrally with the mounting plate and extending therefrom, for guiding the tact plate;
a sleeve formed integrally with the mounting plate and extending therethrough in opposing relation to each tact plate;
a tubular stem slidably received in each sleeve;
a key top formed integrally with the stem on top of it and vertically movably mounted on the mounting plate;
and
an actuating coiled spring having one end portion pressed into the stem and engaged at its other end with the curved portion of the tact plate.

9 more elements

Dependencies are inferred from the claim text.