Data input apparatus having a microcomputer
US5057836A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Aug 10, 1990 |
| Grant date | Oct 15, 1991 |
| Priority date | — |
| Expiry date | Aug 10, 2010 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M11/24
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
A data input apparatus having a first group of lines extending parallel to one another, and a second group of lines extending parallel to one another and intersecting with the lines of the first group at right angles. The apparatus also has groups of key switches located at the intersections of the lines of the first group and the lines of the second group. The lines of the first group are connected to the output ports of a microcomputer. Low-Level pulses are periodically supplied to these lines at different times. The apparatus further comprises a serial circuit including a group of first resistors each connected between adjacent lines of the second group. A voltage source is connected at a connecting point to one end of this serial circuit through a second resistor. The connecting point of the serial circuit and the second resistor is coupled to the input port of the microcomputer. The microcomputer determines which key switch has been operated, in accordance with the voltage applied to the input port at the time a low-level pulse is supplied to the corresponding line of said first group.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.