JPS56155437A - Key code reading circuit - Google Patents
Key code reading circuitInfo
- Publication number
- JPS56155437A JPS56155437A JP5963980A JP5963980A JPS56155437A JP S56155437 A JPS56155437 A JP S56155437A JP 5963980 A JP5963980 A JP 5963980A JP 5963980 A JP5963980 A JP 5963980A JP S56155437 A JPS56155437 A JP S56155437A
- Authority
- JP
- Japan
- Prior art keywords
- key code
- amplifiers
- key
- reading circuit
- lines
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03M—CODING; DECODING; CODE CONVERSION IN GENERAL
- H03M11/00—Coding in connection with keyboards or like devices, i.e. coding of the position of operated keys
- H03M11/20—Dynamic coding, i.e. by key scanning
Landscapes
- Engineering & Computer Science (AREA)
- Theoretical Computer Science (AREA)
- Input From Keyboards Or The Like (AREA)
Abstract
PURPOSE:To lower the operating voltage of a key code matrix by using a capacitor between a special code read line and a scanning line in a key code reading circuit. CONSTITUTION:Scanning lines 13-14 are scanned by decoding the output of a counter 1 with a decoder 2. When one of the keys on the key code matrix is pushed, a key signal is latched in a latch 30 via read lines 21-24 and key code read amplifiers 26-29. Also, a special code is latched in a latch 42 via the special code read line and an amplifier 41. In order to prevent the sneaking by the use of capacitors 36-40, the input impedances of amplifiers 26-29 are made sufficiently lower than the input impedance of the amplifier 41, to make the amplifiers 26-29 inactive to the sneaking signal. Hence, as compared to the prior case in which diodes are used between the special code read lines of the scanning lines, the operating voltage is made lower because there is no voltage drop by the diodes.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5963980A JPS56155437A (en) | 1980-05-02 | 1980-05-02 | Key code reading circuit |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP5963980A JPS56155437A (en) | 1980-05-02 | 1980-05-02 | Key code reading circuit |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS56155437A true JPS56155437A (en) | 1981-12-01 |
JPS6242288B2 JPS6242288B2 (en) | 1987-09-08 |
Family
ID=13118987
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP5963980A Granted JPS56155437A (en) | 1980-05-02 | 1980-05-02 | Key code reading circuit |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS56155437A (en) |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57159328A (en) * | 1981-03-27 | 1982-10-01 | Fujitsu Ltd | Keyboard discriminating system |
JPS585124U (en) * | 1981-06-30 | 1983-01-13 | 富士通株式会社 | keyboard encoder |
JPS5966735A (en) * | 1982-10-08 | 1984-04-16 | Hitachi Ltd | Word processor |
JPS59163626A (en) * | 1983-03-07 | 1984-09-14 | Sanyo Electric Co Ltd | Keyboard identifying system |
-
1980
- 1980-05-02 JP JP5963980A patent/JPS56155437A/en active Granted
Cited By (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS57159328A (en) * | 1981-03-27 | 1982-10-01 | Fujitsu Ltd | Keyboard discriminating system |
JPH0313610B2 (en) * | 1981-03-27 | 1991-02-22 | Fujitsu Ltd | |
JPS585124U (en) * | 1981-06-30 | 1983-01-13 | 富士通株式会社 | keyboard encoder |
JPS5966735A (en) * | 1982-10-08 | 1984-04-16 | Hitachi Ltd | Word processor |
JPS59163626A (en) * | 1983-03-07 | 1984-09-14 | Sanyo Electric Co Ltd | Keyboard identifying system |
JPH0210964B2 (en) * | 1983-03-07 | 1990-03-12 | Sanyo Electric Co |
Also Published As
Publication number | Publication date |
---|---|
JPS6242288B2 (en) | 1987-09-08 |
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