FINGER-TOUCH FACEPLATE

• US 3,696,409 A
• Filed: 12/28/1970
• Issued: 10/03/1972
• Est. Priority Date: 12/28/1970
• Status: Expired due to Term

• Current Assignee: Norman J. Braaten
• Original Assignee: Norman J. Braaten
• Inventors: Braaten, Norman J.
• Primary Examiner(s): Habecker, Thomas B.
• Application Number:
  US05/101,752
• Time in Patent Office: 645 Days
• Field of Search: 340/365C 178/19
• US Class Current: 341/26
• CPC Class Codes: G06F 3/0416 Control or interface arrangements specially adapted for digitisers
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: H03K 17/98 having a plurality of control members, e.g. keyboard
• CPC Class Codes: H03M 11/00 Coding in connection with keyboards or like devices, i.e. coding of the position of operated keys keyboard switch arrangements, structural association of coders and keyboards H01H13/70, H03K17/94

Abstract

A system for identifying a particular position on the face of a display device by simply touching the area with the finger. The area is a conductive pad connected to a relaxation oscillator whose frequency is lowered by the touch. The oscillator is therefore identifiable and a digital computer is enabled to perform a prescribed act such as new information transferred to the display device, dependent upon the location of the area touched.

Claims

1. A touchplate identification system for identifying one of a plurality of touchplates which has been touched by a human being, comprising:

a. a plurality of oscillators, each having a frequency of oscillation controlled by capacitance and resistance connected to the oscillator;

b. a plurality of conductors, each separately connected to the capacitance of an associated oscillator at one end and to an associated touchplate at the other end, the touchplate being adapted to be touched by a human being to change the frequency of oscillation by changing the capacitance;

c. means for sequentially generating an address signal for each of said oscillators;

d. a select matrix operatively connected to said oscillators and said address signal means for selecting one of said oscillators in response to a particular address signal;

e. a counter, for counting the oscillations of said selected oscillator;

f. threshold means for indicating a specified number of oscillations;

g. comparator means, electrically connected to the counter and to the threshold means for comparing the count of oscillations from the counter with the threshold count for a specified time and indicating which is higher;

h. timing means, connected to the comparator means for setting a specified time period; and

i. output means responsive to the comparator means for providing the address signal as an output signal when the oscillation count of the counter is lower than the threshold count.

2. A digital computer input-output system including a display device, having a faceplate, connected to the digital computer, comprising:

a. a plurality of transparent, conductive touchplates attached to the faceplate of the display device;

b. a plurality of oscillators, each having a frequency of oscillation controlled by capacitance and resistance connected to the oscillator;

c. a plurality of conductors, each separately connected to the capacitance of an associated oscillator at one end and to an associated touchplate at the other end, the touchplate being adapted to be touched by a human being to change the frequency of oscillation by changing the capacitance;

d. means for sequentially generating an address signal for each of said oscillators;

e. a select matrix operatively connected to said oscillators and said address signal means for selecting one of said oscillators in response to a particular address signal;

f. a counter, for counting the oscillations of said selected oscillator;

g. threshold means for indicating a specified number of oscillations;

h. comparator means, electrically connected to the counter and to the threshold means for comparing the count of oscillations from the counter with the threshold count for a specified time and indicating which is higher;

i. timing means, connected to the comparator means for setting a specified time period; and

j. output means responSive to the comparator means for providing the address signal as an output signal when the oscillation count of the counter is lower than the threshold count.

3. The system of claim 1, wherein the touchplates are transparent and conductive.

4. The system of claim 1, wherein the oscillators are relaxation oscillators each having a capacitor in an RC charge circuit at the input stage and wherein the associated conductor is connected to the input of the oscillator so that any added capacitance is added in parallel to the input capacitor.

5. The system of claim 1, further including a display device having a faceplate wherein the touchplates are transparent and conductive and are attached to the faceplate of the display device.

6. The system of claim 1 wherein each of the plurality of oscillators has essentially the same free-run frequency.