Capacitive multikey keyboard for inputting data into a computer

• US 4,616,213 A
• Filed: 01/14/1983
• Issued: 10/07/1986
• Est. Priority Date: 01/14/1983
• Status: Expired due to Fees

• Current Assignee: Polytel Corporation
• Original Assignee: Polytel Corporation
• Inventors: Danish, Sherif
• Primary Examiner(s): Caldwell, Sr., John W.
• Assistant Examiner(s): NOT, DEFINED
• Application Number:
  US06/458,142
• Time in Patent Office: 1,362 Days
• Field of Search: 340/365 R, 340/365 S, 340/365 C, 178/18, 178/17 C, 400/494, 400/483, 400/87, 400/122, 200/DIG. 1
• US Class Current: 341/21
• CPC Class Codes: H03K 17/975 using a capacitive movable element
• CPC Class Codes: H03M 11/24 using analogue means , e.g. by coding the states of multiple switches into a single multi-level analogue signal or by indicating the type of a device using the voltage level at a specific tap of a resistive divider

Abstract

A multikey keyboard for inputting data into a computer, wherein pressing a key places in circuit the point of intersection of a row conductor and column conductor respectively connected to portions of separate row and column sequential series of capacitors whose cumulative capacitance correspond to the specific row and columns of the pressed key, thus allowing the computer to establish which key was pressed by measuring the capacitance between the events involving said completed keyboard circuits.

Claims

1. A multikey keyboard for inputting data into a computer comprising:

(a) a first and second separate sequential series of a plurality of capacitors wherein one end of each of said sequential series, respectively, represents the row and column keyboard output to said computer;

(b) a first plurality of essentially parallel conductors representing rows of keys on said keyboard wherein one of said plurality of conductors is connected between each of said capacitors of one of said separate sequential series;

(c) a second plurality of essentially parallel conductors superimposed and essentially perpendicular to said first parallel conductors, thus representing columns of keys, wherein one of said second plurality of conductors is connected between each of said capacitors of said other separate sequential series;

(d) a plurality of normally open, key activated, switch means located at the intersection of the row and column conductors forming a matrix keyboard; and

(e) a common circuit lead operatively connected to each of said plurality of switch means such that when a key is pressed, the corresponding normally open switch means closes thus completing the circuit between said common circuit lead and that portion of both of said sequential series of said plurality of capacitors cumulatively corresponding to the capacitance associated with the row and column of said pressed key, thus allowing the computer to establish which key was pressed by measuring the capacitance of said completed keyboard circuits between said common circuit lead and each of said ends of said sequential series representing the row and column keyboard output as the relative position of said pressed key.

3. A multikey keyboard of claim 1 or 2 wherein the individual capacitance values within said sequential series of capacitors are increased nonlinearly such as to enhance the computer'"'"'s ability to discriminate which key was pressed.

4. A multikey keyboard of claim 3 further comprising a sensor conductor output circuit means which when a key of one of said switch means is pressed completes the circuit between said common circuit lead and said sensor conductor output circuit means, thus outputting a separate signal to the computer indicating that a key has been pressed and that the capacitance measurement should take place.

5. A multikey keyboard of claim 1 or 2 wherein said keyboard further comprises two opposed printed circuit sheets separated by an insulated sheet perforated at the position of the keys such that said switch means is created by having at least one of said opposed printed circuit sheets being sufficiently flexible such that said flexible sheet may be pressed at the position of said key thus completing said capacitive row and column keyboard output of said computer by physically contacting said printed circuit sheets to each other.

6. A multikey keyboard of claim 4 wherein said keyboard further comprises two opposed printed circuit sheets separated by an insulated sheet perforated at the position of the keys such that said switch means is created by having at least one of said opposed printed circuit sheets being sufficiently flexible such that said flexible sheet may be pressed at the position of said key thus completing said output circuit by physically contacting said printed circuit sheets to each other.

7. A multikey keyboard of claim 5 wherein said capacitors are deposited on said printed circuit sheets.

8. A multikey keyboard of claim 1 wherein said capacitors are deposited on said printed circuit sheets.

9. A multikey keyboard of claim 6 wherein said capacitors are deposited on said printed circuit sheets.

10. A multikey keyboard of claim 7 further comprising an information panel associated with said keys so as to effect the corresponding data inputs by pressing the chosen keys.

11. A multikey keyboard of claim 8 further comprising an information panel associated with said keys so as to effect the corresponding data inputs by pressing the chosen keys.

12. A multikey keyboard of claim 9 further comprising an information panel associated with said keys so as to effect the corresponding data inputs by pressing the chosen keys.

13. A multikey keyboard of claim 10 wherein said information is in Braille.

14. A multikey keyboard of claim 11 wherein said information is in Braille.

15. A multikey keyboard of claim 12 wherein said information is in Braille.

16. A multikey keyboard of claim 10 wherein said informational panel is an overlay with deformed key tabs.

17. A multikey keyboard of claim 11 wherein said informational panel is an overlay with deformed key tabs.

18. A multikey keyboard of claim 12 wherein said informational panel is an overlay with deformed key tabs.

2. A multikey keyboard for inputting data and commands into a computer comprising:

(a) a plurality of normally open, key activated, switch means;

(b) a common circuit lead operatively connected to each of said plurality of switch means;

(c) a set of n essentially parallel first conductors wherein each first conductor represents up to y rows or subset of rows of keys and wherein each first conductor is connected to at least one separate sequential series of a plurality of up to y capacitors, thus forming n separate row outputs to the computer;

(d) a set of m essentially parallel second conductors wherein each second conductor represents up to x columns or subsets of columns of keys and wherein each second conductor is connected to at least one separate sequential series of a plurality of up to x capacitors, thus forming m separate column outputs to the computer and wherein said set of essentially parallel row and column conductors are superimposed such that said plurality of normally open, key activated, switch means are located at the intersection of the sets of row and column conductors such that when a key is pressed the corresponding normally open switch closes thus completing the circuit between said common circuit lead and n row output conductors and m column output conductors thus allowing for a n times x by m times y matrix of keys;

where n, m, x, and y are integers.