The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jul. 23, 2002
Filed:
Apr. 13, 1999
Paul G. Schnizlein, Austin, TX (US);
Kenneth Tallo, Austin, TX (US);
Legerity, Inc., Austin, TX (US);
Abstract
The invention is, in its various aspects, an apparatus and a method for scanning a keypad or a keyboard. The apparatus comprises a keypad and an integrated circuit. The keypad includes a plurality of chained resistors and a plurality of key switches. Each of the plurality of key switches is tied to a common node at a first terminal thereof and tapping the chained resistors at a second node thereof. Each of the key switches generates a signal indicative of the respective key switch being pressed when the key switch is pressed. The integrated circuit is capable of receiving the generated signal. The integrated circuit furthermore includes an analog to digital converter capable of generating a reference signal and a circuit capable of determining which key switch has been pressed from the magnitude of the generated voltage signal and the reference signal. The method for scanning a keypad comprises generating a voltage signal whose magnitude indicates which key is being pressed, and determining from the magnitude of the generated voltage signal which key was pressed.