Membrane keyboards
Patent 4920237 Issued on April 24, 1990. Estimated Expiration Date: 
February 2, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.
February 2, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent References 3503031 Method of fabricating keyboard apparatus Method of manufacturing a keyboard Push-button switch Touchpad keyboard Analog integrated circuit pressure sensor Membrane switch element with coated spacer layer Patent #: 4795861 InventorsApplicationNo. 305585 filed on 02/02/1989US Classes:200/5A, With independent operators200/517, Including additional actuator341/22, Including keyboard or keypad361/680, Including keyboard support400/479, Via electrical component (e.g., switch, stylus, etc.) in or with key-board400/689Means for muffling typewriter noiseExaminersPrimary: Burr, Edgar S.Assistant: Cohen, Moshe I. Attorney, Agent or FirmForeign Patent References
International ClassesH01H 001/14B41J 019/04 B41J 029/10 AbstractA membrane keyboard has two spaced flexible membranes (1 and 2) carrying contact pad assemblies. Acoustic pads (15) of expanding ink are printed on the top surface of the upper membrane (2) between the contact pads (4) and the key buttons used to operate the contact switches formed by the pairs of opposed contact pads, thus reducing the acoustic noise and improving the contact bounce characteristic.Optionally, printed expanding ink is also used to form the spacer (5) between the membranes (1 and 2).Other References
Field of SearchVia electrical component (e.g., switch, stylus, etc.) in or with key-boardMeans for muffling typewriter noise KEY-BOARD OR KEY LEVER-ACTUATING MECHANISM By sound-barrier enclosure for typewriter (e.g., by sound-absorbing material) And externally protruding (e.g., key-board, etc.) operating means With externally protruding operating means With independent operators Membrane type Specitic nonconductive materials Including additional actuator Including keyboard or keypad Pressure sensitive actuation | |
