WO1985000713A1 - Dispositifs de claviers d'introduction de donnees - Google Patents

Dispositifs de claviers d'introduction de donnees Download PDF

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Publication number
WO1985000713A1
WO1985000713A1 PCT/GB1984/000255 GB8400255W WO8500713A1 WO 1985000713 A1 WO1985000713 A1 WO 1985000713A1 GB 8400255 W GB8400255 W GB 8400255W WO 8500713 A1 WO8500713 A1 WO 8500713A1
Authority
WO
WIPO (PCT)
Prior art keywords
key
keyboard
row
column
connector
Prior art date
Application number
PCT/GB1984/000255
Other languages
English (en)
Inventor
Martin Christopher Cassey
Perran Vincent Leonard Newman
Original Assignee
Prutec Limited
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Prutec Limited filed Critical Prutec Limited
Publication of WO1985000713A1 publication Critical patent/WO1985000713A1/fr

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
    • H03M11/003—Phantom keys detection and prevention

Definitions

  • Keyboard input devices This invention relates to keyboard input devices and methods of data input using keyboards.
  • keyboard is used herein for simplicity of expression but it is to be understood as including not only keyboards consisting of an array of individual switch members, each of which normally bears an identifying indicium or more than one identifying indicium corresponding to alphabetic letters in the Roman or other alphabets, numerals and/or other signs, graphic symbols and the like, but also any other arrangement consisting of an array of .individually identified locations, for example touch sensitive individual areas.
  • Keyboards are widely used as input devices to microprocessor based systems. Such systems include wordprocessing systems, computer terminal systems and control systems for, e.g. numerically controlled machine tools. In many of these applications it is ' convenient and, in some applications it may be imperative to site the keyboard as a separate unit from the micro ⁇ processor. The separation may be relatively small, e.g. to allow a keyboard unit to be moved around a desk, or may be substantial, e.g. to enable a keyboard to be operated in a hostile environment but to preserve the microprocessor system away from such environment.' A normal keyboard contains at least 26 keys corresponding to the 26 letters of the Roman alphabet plus some function or shift keys and conveniently some other keys, e.g. for punctuation marks.
  • Separate keys may be provided for numerals and it is not unusual therefor for an operative keyboard to include more than 40 keys.
  • Simply connecting these via conventional wires would accordingly require a substantial ulti-conductor cable and a large number of physical inter-connections e.g. a plug and socket arrangement having more than 40 pins. This is expensive and can be unreliable in practice.
  • One solution to the problem which has been adopted in the past is .to provide the keyboard with encoder circuitry which converts the state of the keyboard into a suitable serial output signal which can be transmitted to a central microprocessor unit. " We have now found that a simple and accordingly very reliable keyboard may be produced which requires only a few inter-connections to the main micro ⁇ processor unit by using a keyboard matrix scanning system driven using clock pulses from the main icro- processor unit.
  • a keyboard consisting of an array of individually identifiable key elements, a row and column matrix of connectors, each key element being uniquely associated with one intersection between a connector element in a row and a connector element in a column, means for altering the electrical characteristics between the connector in the respective row and the connector in the respective column when a key element is actuated and means for sequentially scanning all of the inter ⁇ sections between all of the rows and columns of connectors to determine the electrical condition of each intersection and for feeding a signal derived from such scanning to an output terminal.
  • the signal at the output terminal from such a keyboard accordingly consists of a series of blocks each one of which may vary from the previous one or may be the same if nothing has been actuated or de-actuated on the keyboard between one scan and the next.
  • microprocessor electronics may sort out the output signal to give an indication of whether any is actuated and if so, which.
  • the microprocessor electronics may also sort out when two keys are actuated in a meaningful way, e.g. a shift key and a normal key or it may also sort out an invalid entry, for example when three keys are simultaneously depressed.
  • the microprocessor circuitry may be suitably programmed to convert the keyboard output to any desirable useful form and such programming forms no part of the present invention.
  • the microprocessor unit is however used normally to clock or drive the keyboard so as to impart an appropriate timing on the keyboard scanning.
  • the size of the row and column matrix of connectors may vary depending upon the use in question.
  • a useful size is 16 units by 8 giving 128 intersections thus allowing a full alphabetic and numerical keyboard as on a typewriterplus a standard numerical 0 to 9 array plus the standard mathematical function keys and leaving space for several specialised function keys which in any particular system may be dedicated or may be "user programmable".
  • the intersections each associated with a key element may be scanned using simple integrated circuits and the results of the scan fed as successive series each of 128 pulses, each pulse being conveniently thought of as a "0" or "1".
  • the data signal appearing at the output of the keyboard which is processed by the main microprocessor unit will consist of a string of O's with one or a few 1's interposed in it.
  • the main microprocessor can work out which key or keys is/ are actuated depending on how many and the position of the 1's in the string of O's it receives.
  • the scanning may take place very rapidly, for example, 250 timesper second and this enables reliable interpretation of the state of the keyboard even if data is being entered into the keyboard very fast, i.e a very fast typist is operating it.
  • the keyboards of the present invention are particularly useful in connection with wordprocessing devices and analogous office machines where a movable keyboard unit connected by a highly flexible
  • O P ⁇ connector to a main microprocessor and display unit can be much more convenient to operate than a large fixed piece of equipment.
  • the invention is illustrated with reference to a keyboard unit suitable for use in office wordprocessor apparatus.
  • Typists are used to a shift key but require some indication of when the shift key is "depressed". In any electronic system, this is most conveniently effected by using light emitting diode in a key which is pressed once to shift, whereon the diode lights, and pressed again to release the shift.
  • the accompanying drawing shows the circuit diagram for such a keyboard.
  • the basic keyboard consists of a number of key switches (not shown) each of which is associated with the intersection between two conductors.
  • Each of the two conductors is part of a parallel array of - such conductors, the two parallel arrays being crossed to form an 8 by 16 matrix.
  • the key switches are located.
  • Each key switch is a standard type of momentary action key which has associated with it a silicon diode connected in series with the switch contacts. The presence of the diode in each key unit allows the decoding system, i.e.
  • the diode also has the function of protecting the outputs of one of the integrated circuits from damage if two keys in .the same row but di erent columns are simultaneously depressed. In the absence of such diodes, the two column outputs in such a case would be effectively shorted together leading to excessive current flow and possible damage to the integrated circuits.
  • the basic ciruitry consists of three CMOS integrated circuits being a dual four bit binary counter type 4520, a four to sixteen line decoder type 4514 and an eight to one line encoder type 4512.
  • CMOS integrated circuits being a dual four bit binary counter type 4520, a four to sixteen line decoder type 4514 and an eight to one line encoder type 4512.
  • there are also a few discrete components being C1 and C2 across the five volt power supply, and an array of two resistors, an LEDand a 2N3704 transistor for the shift indication and a set of eight 47K pull-down resistors connected to each of the data input lines to the 4512 encoder in order to discharge the appreciable capacitance of these input lines so as to prevent "ghosting" of keys in adjacent rows.
  • the keyboard is connected to a main microprocessor unit via a six-core screened spiral cord, for example, which may be connected using, e.-g. a standard seven-pin DIN plug.
  • incoming clock pulses from the microprocessor unit increment the dual four-bit counter by one count per pulse.
  • the count sequence is straight binary and is eight-bits long giving a range of output values from the counter running from 0 to 255.
  • the counter automatically resets thereafter and the count sequence restarts from 0.
  • the most significant output from the counter is not used so the effective count sequence is from 0 to 127.
  • the three least significant outputs from the counter are fed to the address outputs of the eight to one line encoder 4512 while the next foremost significant outputs address the four to 16 line encoder type 4514.
  • the 16 outputs from the 4514 are fed to the 16 column connectors as shown on the diagram and the eight row connectors are connected to the eight inputs of the eight to one line encoder type 4512.
  • Each column line is accordingly set to logic high for eight clock pulses while the encoder IC 4512 scans the eight rows in sequence to see if any of the keys at the intersection are depressed.
  • the output data from IC 4512 thus corresponds to a string of logical O's and 1's at the same frequency as the clock pulses and the depression of a particular key is uniquely represented in the output at data output 6 shown on the drawing by the position of a 1 in the set of 128 1's or 0's.
  • the output data stream may be suitably decoded using a microprocessor in any convenient fashion.
  • One convenient way of effecting it is to clock the data received from the data output into an eight-bit serial to parallel shift register the output of which is then read in parallel by a 6801 microprocessor. • That same microprocessor may generate the clock pulses fed to the keyboard and to the clock input of the shift register. The microprocessor may read the shift register output every eight clock pulses and repeat this 16 times to scan the entire keyboard. The microprocessor may be prgra med to generate after the complete of each scanning sequence a reset signal which is sent to the keyboard via the reset input thereof.
  • the microprocessor unit is also programmed to detect a depression of the shift key on the keyboard and to generate a signal to actuate the shift indicator LED via input 1 to the keyboard.

Landscapes

  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Input From Keyboards Or The Like (AREA)

Abstract

Les claviers électroniques ci-décrits sont particulièrement utiles dans des équipements de traitement de texte. Sous une rangée de touches, par exemple des touches alphanumériques est placée une matrice en rangées et colonnes de connecteurs. Chaque touche est par exemple un commutateur ayant une diode en série et agencé pour modifier les caractéristiques électriques d'une intersection entre un connecteur d'une rangée et un connecteur d'une colonne. Les rangées et les colonnes sont balayées séquentiellement pour produire un flot de données de sortie qui peuvent être décodées électroniquement pour voir quelle est la touche ou quelles sont les touches qui ont été enfoncées.
PCT/GB1984/000255 1983-07-27 1984-07-19 Dispositifs de claviers d'introduction de donnees WO1985000713A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
GB838320294A GB8320294D0 (en) 1983-07-27 1983-07-27 Keyboard input devices
GB8320294 1983-07-27

Publications (1)

Publication Number Publication Date
WO1985000713A1 true WO1985000713A1 (fr) 1985-02-14

Family

ID=10546392

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/GB1984/000255 WO1985000713A1 (fr) 1983-07-27 1984-07-19 Dispositifs de claviers d'introduction de donnees

Country Status (4)

Country Link
EP (1) EP0151597A1 (fr)
AU (1) AU3153284A (fr)
GB (1) GB8320294D0 (fr)
WO (1) WO1985000713A1 (fr)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2599525A1 (fr) * 1986-06-02 1987-12-04 Dassault Electronique Unite a clavier de securite, en particulier pour la composition d'un code confidentiel
DE4111329C1 (en) * 1991-04-08 1992-12-24 S. Siedle & Soehne Telefon- Und Telegrafenwerke Stiftung & Co, 7743 Furtwangen, De Keyboard scanning appts. for detecting key depressions - identifies key from return line and from temporal location of pulse on line, using shift register and processor

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4199750A (en) * 1975-11-10 1980-04-22 Hitachi, Ltd. Key input circuit capable of roll-over operation
US4222038A (en) * 1978-02-24 1980-09-09 Motorola, Inc. Microcomputer keyboard input circuitry
US4234872A (en) * 1978-03-08 1980-11-18 Lgz Landis & Gyr Zug Ag Circuit arrangement for a keyboard

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4199750A (en) * 1975-11-10 1980-04-22 Hitachi, Ltd. Key input circuit capable of roll-over operation
US4222038A (en) * 1978-02-24 1980-09-09 Motorola, Inc. Microcomputer keyboard input circuitry
US4234872A (en) * 1978-03-08 1980-11-18 Lgz Landis & Gyr Zug Ag Circuit arrangement for a keyboard

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
IBM Technical Disclosure Bulletin, Volume 25, No. 11A, April 1983 (New York, US) JEANNIOT et al.: "Low-Cost Keyboard Scanner", pages 5777-5778, see figure; pages 5777-5778 *
Microprocessors, Volume 2, No. 2, 1 April 1978 (London, GB) MUNT: "Microprocessors Keyboard Encoding", pages 67-70, see figure 1; page 68, right-hand column, line 38 - page 69, left-hand column, line 15 *

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2599525A1 (fr) * 1986-06-02 1987-12-04 Dassault Electronique Unite a clavier de securite, en particulier pour la composition d'un code confidentiel
EP0248712A1 (fr) * 1986-06-02 1987-12-09 Electronique Serge Dassault Unité de clavier de sécurité, en particulier pour la composition d'un code confidentiel
DE4111329C1 (en) * 1991-04-08 1992-12-24 S. Siedle & Soehne Telefon- Und Telegrafenwerke Stiftung & Co, 7743 Furtwangen, De Keyboard scanning appts. for detecting key depressions - identifies key from return line and from temporal location of pulse on line, using shift register and processor

Also Published As

Publication number Publication date
GB8320294D0 (en) 1983-09-01
AU3153284A (en) 1985-03-04
EP0151597A1 (fr) 1985-08-21

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