Keyboard apparatus

• US 4,136,336 A
• Filed: 03/15/1977
• Issued: 01/23/1979
• Est. Priority Date: 03/19/1976
• Status: Expired due to Term

• Current Assignee: Pentel Kabushiki Kaisha
• Original Assignee: Pentel Kabushiki Kaisha
• Inventors: Abe, Kiyomi, Kameda, Hidetoshi
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): Crosland, Donnie L.
• Application Number:
  US05/777,826
• Time in Patent Office: 679 Days
• Field of Search: 340/365 R, 340/365 C, 340/365 L, 340/365 S, 340/365 P, 340/146.3 AQ, 340/146.3 SY, 178/18, 178/19, 178/17 A, 178/17 C, 197/98, 197/100, 179/90 K, 200/5 A, 400/472, 400/473, 400/486, 400/475, 400/477
• US Class Current: 341/5
• CPC Class Codes: G06F 3/0238 Programmable keyboards key guide holders G06F3/0224

Abstract

A keyboard apparatus includes a pair of juxtaposed tablets against which a single probe or signal pen may be applied through an overlay or overlays. Each tablet has a multiplicity of key segments defined on its surface at specified coordinates. Each segment is operable as a key as the probe is applied against a particular overlay which assumes an open position over a selected one of the tablets. A plurality of overlays are bound in a binder or fastener in the form of a book so that any overlay can assume an open position on either tablet. Each overlay has indicium segments on its surface which coorespond to the key segments and on which indicia such as letters or characters designating the key segments may be entered. When a particular overlay assumes an open position on one of the tablets, a probe may be applied against a desired indicium segment thereof, whereupon the probe senses a signal from the corresponding key segment. Means is provided for sensing which one of the overlays assumes an open position on the associated tablet and for producing a detection signal. A sensed key signal and the detection signal are combined to provide a digital signal which identifies the desired indicium segment on the particular overlay.

Claims

1. A keyboard apparatus comprising a pair of tablets each internally carrying two sets of driver lines spaced apart and disposed along coordinate axes and each having its surface subdivided into a multiplicity of key segments associated with each point of intersection between the sets of driver lines;

two pairs of scanning units, each pair of scanning units being connected with the two sets of driver lines of one of the tablets, the scanning units being alternately activated to supply a drive signal to the sets of driver lines in a manner such that at least one of each pair of scanning units supplies one set of driver lines of the associated tablet with a drive signal which is time displaced from any drive signal supplied by one of the other pair of scanning units;

an overlay unit including a plurality of overlays bound in the form of a book so that each overlay can assume an open position on either tablet, each overlay having indicium segments at positions corresponding to the key segments;

a selection switching device for producing a signal which identifies which one of the overlays assumes an open position on at least one of the tablets;

a probe for sensing the drive signal from a desired key segment on a selected one of the tablets through the overlays disposed on the tablet; and

a control unit for supplying a control signal to each of the scanning units and for receiving an output signal from the probe, the control unit producing a digital signal indicative of a desired indicium segment of a particular overlay which assumes an open position on the selected tablet and against which the probe is applied, said particular overlay being specified by an output signal from the selection switching device.

2. A keyboard apparatus according to claim 1 in which one set of driver lines of one tablet is supplied with the drive signal from the corresponding scanning unit subsequent to the supply of the drive signal to one set of driver lines of the other tablet from the corresponding scanning unit and in which the other set of driver lines of said one tablet is supplied with the drive signal simultaneously with the other set of driver lines of the other tablet.

3. A keyboard apparatus according to claim 1 in which the probe is capacitively coupled with the tablet.

4. A keyboard apparatus comprising a pair of tablets each internally carrying two sets of driver lines which are spaced apart and disposed along coordinate axes and having its surface subdivided into a multiplicity of key segments each associated with a point of intersection between the set of driver lines;

two pairs of scanning units, each pair of scanning units being connected with the two sets of driver lines of one of the tablets, the scanning units being alternately activated for supplying a drive signal to the sets of driver lines in a sequential manner such that at least one of each pair of scanning units supplies one set of driver lines of the associated tablet with a drive signal which is time displaced from any drive signal supplied by one of the other pair of scanning units;

an overlay unit including a plurality of overlays bound in the form of a book so as to permit each overlay to assume an open position over either one of the tablets, each overlay having indicium segments at positions corresponding to the key segments;

a selection switching device for producing a signal which identifies which one of the overlays assumes an open position on at least one of the tablets;

a probe for sensing the drive signal from a desired key segment on a selected one of the tablets through the overlays disposed thereon;

a control unit for supplying a control signal to each of the scanning units and for receiving an output signal from the probe, the control unit producing a digital signal indicative of a desired indicium segment of a particular overlay which assumes an open position on the selected tablet and against which the probe is applied, the particular overlay being specified by an output signal from the selection switching device;

a detection circuit for detecting the number of overlays on at least one of the tablets; and

a control voltage adjusting circuit responsive to an output from the detection circuit for adjusting the magnitude of the control voltage supplied to each pair of scanning units associated with each tablet.

5. A keyboard apparatus according to claim 4 in which the detection circuit operates in conjunction with the operation of the selection switching device.

6. A keyboard apparatus according to claim 4 in which the control voltage adjusting circuit comprises a pair of circuit arrangements, which adjust the magnitude of the control voltage supplied to the respective pairs of the scanning units in inverse relationship to each other.

7. A keyboard apparatus according to claim 6 in which each of the circuit arrangements comprises a plurality of resistive paths having different resistance values and connected to shunt with a common voltage source, and a plurality of switches which select one of the resistive paths.

8. A keyboard apparatus according to claim 6 in which each of the circuit arrangements comprises a plurality of parallel paths connected with voltage sources of mutually different magnitudes, and a plurality of switches for selecting one of the parallel paths.

9. A keyboard apparatus comprising a tablet internally carrying two sets of driver lines spaced apart and disposed along coordinate axes and each having its surface subdivided into a multiplicity of key segments each associated wtih a point of intersection between the set of driver lines;

a pair of scanning units connected with the two sets of driver lines of the tablet, the scanning units being alternately activated for supplying a drive signal to the sets of driver lines in a sequential manner;

a plurality of overlays each having indicium segments at positions corresponding to the key segments;

a selection switching device for producing a signal which identifies which one of the overlays assumes an open position on the tablet;

a probe for sensing the drive signal from a desired key segment on the tablet through the selected number of overlays disposed thereon;

a control unit for supplying a control signal to the scanning units and for receiving an output signal from the probe, the control unit having means for producing a digital signal indicative of a desired indicium segment of a particular overlay which assumes an open position on the tablet and against which the probe is applied, the particular overlay being specified by an output signal from the selection switching device;

a detection circuit for detecting the number of overlays on the tablet; and

a voltage adjusting circuit responsive to an output from the detection circuit for adjusting the magnitude of the voltage of the drive signal supplied to the sets of driver lines.

10. A keyboard apparatus according to claim 9 in which the control voltage adjusting circuit comprises means defining a plurality of resistive paths having different resistance values and connected in shunt with a common voltage source, and a plurality of switches to select one of the resistive paths.

11. A keyboard apparatus according to claim 9 in which the control voltage adjusting circuit comprises means defining a plurality of parallel electrical paths connected with voltage sources of mutually different magnitudes, and a plurality of switches for selecting one of the parallel paths.