CODED CARD AND READER THEREFOR

• US 3,699,311 A
• Filed: 01/25/1971
• Issued: 10/17/1972
• Est. Priority Date: 01/25/1971
• Status: Expired due to Term

• Current Assignee: Robert A. Dunbar
• Original Assignee: Robert A. Dunbar
• Inventors: Dunbar, Robert A.
• Primary Examiner(s): Cook, Daryl W.
• Application Number:
  US05/109,114
• Time in Patent Office: 631 Days
• Field of Search: 235/61.11H,61.11A 340/173SP,173R,347P
• US Class Current: 235/451
• CPC Class Codes: G06K 7/081 electrostatic, e.g. by detecting the charge of capacitance between electrodes

Abstract

A card contains selectively connected or unconnected plates to encode bits of information. A card reader has a sending plate and a sensing plate for each bit encoded in the card, the plates of the card and the reader forming two capacitors in series to read bits of information encoded in the card. A potential impressed on the sending plate causes a charge redistribution and a momentary current flow which is sensed by a high impedance sensing circuit connected to each sensing plate, the momentary current flow and resulting voltage only being present to be sensed when the plates encoding a bit of information in the card are connected. The sending plates in the card reader and one of the plates encoding each bit of information in the card may be formed as single larger plates.

Claims

1. A card having bits of information encoded therein and a reader for said card comprising, in combination, a card containing selectively connected plates disposed in a single layer for each bit encoded therein, a card reader having at least one sending plate and a sensing plate for each bit encoded in said card, said at least one sending plate and said sensing plates being substantially the same shape and size as and corresponding to said plates in said card when said card is presented to said card reader, said plates in said card and said card reader forming two capacitors selectively connected in series for each bit encoded in said card, means impressing a voltage on said at least one sending plate, and means to sense a resulting momentary current flow and voltage from said sensing plates to read the bits of information encoded in said card.

2. The combination according to claim 1 wherein one of each of said selectively connected plates in said card is formed as a single plate, said at least one sending plate of said card reader being a single plate corresponding to said single plate of said card.

3. The combination according to claim 2 with the addition of selectively interrupted strips in said card connecting said single plate in said card to each other plate in said card.

4. The combination according to claim 3 wherein said single plate in said card is elongated, other plates in said card being disposed in rows parallel to said single plate, said connecting strips extending from said single plate to each other plate in said card.

5. The combination according to claim 4 wherein said plates in adjacent rows are staggered relative to each other, said connecting strips extending between plates of rows closer to said single plate to the plates of more distant rows.

6. The combination according to claim 5 wherein said single plate in said card is a central plate, said rows of plates being disposed on both sides thereof.