Communications: electrical – Audible indication – Percussion-type sound producer
Patent
1982-11-12
1988-04-12
Caldwell, Sr., John W.
Communications: electrical
Audible indication
Percussion-type sound producer
310340, 310345, G06F 302
Patent
active
047377674
ABSTRACT:
A housing, preferably electrically conductive, defines individual areas for depression to identify individual indicia, e.g., number, alphabetical letters. A hard, electrically insulating material attached to the housing transmits strains produced by the depression of the individual areas on the housing. A plurality of thin electrically insulating sheets are attached to the hard insulating material at the individual areas in the housing. A plurality of thin electrically conductive sheets attached to the thin insulating sheets. The insulating sheets and the conductive sheets may constitute printed circuit segments. A plurality of ceramic crystals are attached to individual ones of the conductive sheets. The electrically conductive sheets are preferably coupled electrically to the housing. This causes one surface of each crystal to be common to the adjacent area. When the keyboard is depressed in the adjacent keyboard area, each crystal becomes stressed and causes an electrical signal to be generated on the ungrounded surface of the crystal.
REFERENCES:
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patent: 3732389 (1973-05-01), Kaelin
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patent: 4296406 (1981-10-01), Pearson
patent: 4412210 (1983-10-01), Washizuka
patent: 4433223 (1984-02-01), Larson
Kompanek Harry W.
Ligman James R.
Caldwell Sr. John W.
KDC Corporation
Queen Tyrone
Roston Ellsworth R.
Schwartz Charles H.
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