N-key rollover keyboard without diodes
First Claim
Patent Images
1. A keyboard for use with a computer, the keyboard being connected to the computer by a cable to receive power and ground and a serial communications link, the keyboard comprising:
- a plurality of keys, including alphanumeric, function and control keys, each key having a mechanical contact, wherein the first side of said mechanical contact of each key is connected to a common voltage level;
an integrated circuit including;
a plurality of pins, said pins including a plurality of power pins for connection to power and ground voltages, a plurality of serial interface pins for connection to the serial communications link in the cable and a plurality of key contact pins equal to the number of said plurality of keys for individual, direct connection to the second side of said mechanical contact of each key; and
logic means connected to said plurality of pins for monitoring key closures and providing serial data representative of the key contact closure status to the computer over the serial communications link; and
a circuit board receiving said plurality of keys and said integrated circuit and having connections for receiving the cable, said circuit board having circuit traces for connecting said cable to said integrated circuit serial interface pins and said power and ground voltage pins, for connecting said integrated circuit key contact pins to said second side of said key contacts and for connecting said first side of said key contacts to said common voltage level.
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Accused Products
Abstract
A n-key rollover keyboard having an application specific integrated circuit (ASIC) with a large number of pins, each pin directly connected to a key contact, with the other side of the key contact connected to ground. The direct wire arrangement allows use of a single sided circuit board. The keyboard has a reduced cost over prior n-key rollover designs by allowing removal of the series diodes and double sided circuit board.
17 Citations
7 Claims
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1. A keyboard for use with a computer, the keyboard being connected to the computer by a cable to receive power and ground and a serial communications link, the keyboard comprising:
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a plurality of keys, including alphanumeric, function and control keys, each key having a mechanical contact, wherein the first side of said mechanical contact of each key is connected to a common voltage level; an integrated circuit including; a plurality of pins, said pins including a plurality of power pins for connection to power and ground voltages, a plurality of serial interface pins for connection to the serial communications link in the cable and a plurality of key contact pins equal to the number of said plurality of keys for individual, direct connection to the second side of said mechanical contact of each key; and logic means connected to said plurality of pins for monitoring key closures and providing serial data representative of the key contact closure status to the computer over the serial communications link; and a circuit board receiving said plurality of keys and said integrated circuit and having connections for receiving the cable, said circuit board having circuit traces for connecting said cable to said integrated circuit serial interface pins and said power and ground voltage pins, for connecting said integrated circuit key contact pins to said second side of said key contacts and for connecting said first side of said key contacts to said common voltage level. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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Specification