Integrated circuit for a keyboard of an electronic apparatus
US4518951A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jun 24, 1982 |
| Grant date | May 21, 1985 |
| Priority date | — |
| Expiry date | Jun 24, 2002 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/20
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
This circuit, controlled by the counter (Z) and via the row transistors (ZTm) and upon actuation of a pushbutton key, successively interrogates the row lines (1m) and, via the column line (2n) as connected to the row line, forms an inverter with the corresponding resistor (SRn), so that an L level will appear at the input of the corresponding column inverter (SI1n). In the ROM-type matrix (M), with the aid of the matrix transistors (T . . . ) and the resistors (MRmn) it is accomplished that the m.multidot.n lines (Lmn) are only controlled in such a way that the corresponding line conducts an H level upon actuating only one single pushbutton key of the keyboard (TF). Accordingly, a l-ex-m-times-n code appears on the lines (Lmn) which, via the NOR gate (N) also effects the release of the counter (Z) counting the clock pulses of the clock pulse generator (TG).
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.