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Modular Hall Effect Keyboard

IP.com Disclosure Number: IPCOM000078922D
Original Publication Date: 1973-Apr-01
Included in the Prior Art Database: 2005-Feb-26
Document File: 2 page(s) / 66K

Publishing Venue

IBM

Related People

Andrews, LP: AUTHOR [+2]

Abstract

A standard key element including a Hall element, generates unique data output for each key position from logic circuitry included in a Hall amplifier circuit, which is mounted on a printed-circuit board. Data outputs from the keys may be changed by substituting different printed-circuit board patterns. The keyboard may be expanded to any number of keys.

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Modular Hall Effect Keyboard

A standard key element including a Hall element, generates unique data output for each key position from logic circuitry included in a Hall amplifier circuit, which is mounted on a printed-circuit board. Data outputs from the keys may be changed by substituting different printed-circuit board patterns. The keyboard may be expanded to any number of keys.

Fig. 1 shows an integrated circuit Hall module 10 associated with each key element, not shown. Each module 10 includes a Hall element 12, differential amplifier 14 and Schmitt trigger 16 which drive a logical network 18 to generate complete keyboard languages, such as "ASCII" or EBCDIC" at the output of four transistors 20 having open collectors. A Hall element 12 initiates a signal whenever a key element having a permanent magnet, not shown, is brought in close proximity to an associated integrated circuit 10. The Hall voltage is amplified by the differential amplifier 14. The amplified Hall signal is transformed into a digital switching voltage by the trigger 16. The logic 18 generates the data output signals at the transistors 20. The DC interlock input/output is used for Strobe Generation, and repeat input inhibit during typamatic mode. A repeat signal at terminal 22, originated from another key element, generates automatic repetitive key depressions referred to as "typamatic action".

Fig. 2 shows a portion of a printed-circuit board 28 having conductive patterns 30 and 32 on oppos...