Electrostatic discharge protection in a portable communication device
AssigneeTelefonaktiebolaget LM Ericsson
InventorGöran Persson
Life of this patent
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Abstract
A portable communication device has an electronic circuit board arranged inside a housing, and a keypad, the individual keys of which are arranged, when depressed, to collapse a respective tactile dome on a domefoil interposed between the keypad and the circuit board, so as to establish electric contact with a respective contact point on the circuit board. The domefoil is formed as a non-conductive sheet providing an airtight and/or electrostatic seal between the keypad and the circuit board. The domefoil protects the circuit board from electrostatic discharge.
Claims4
A portable communication device, comprising an electronic circuit board arranged inside a housing, and a keypad, individual keys of which are arranged, when depressed, to collapse a respective tactile dome on a domefoil interposed between the keypad and the circuit board, so as to establish electric contact with a respective contact point on the circuit board, wherein
- said domefoil is formed as a non-conductive sheet providing an electrostatic seal between the keypad and the circuit board, said domefoil thereby protecting the circuit board from electrostatic discharge (ESD);
- and
- an electrically conductive layer is provided in an interior of the domefoil and is connected to ground means, said layer thereby inhibiting electromagnetic interference between the device and its surroundings.
A method of protecting a keypad-operated device from electrostatic discharge between a keypad and an electronic circuit board inside the device, comprising a step of
- providing the device with a domefoil, comprising a set of tactile domes and at least an entire front surface of which being made from an electrically isolating material, as an electrostatic seal between the keypad and the circuit board;
- and
- providing an interior of the domefoil with an electrically conductive and grounded layer, said layer acting as an electromagnetic shield between the circuit board and electronic equipment external to the device.
Dependencies are inferred from the claim text.