Machine readable memory card with capacitive interconnect

• US 4,931,991 A
• Filed: 12/22/1988
• Issued: 06/05/1990
• Est. Priority Date: 12/22/1988
• Status: Expired due to Fees

• Current Assignee: AMP Incorporated (Johnson Controls International plc)
• Original Assignee: AMP Incorporated (Johnson Controls International plc)
• Inventors: Cvijanovich, George B.
• Primary Examiner(s): Moffitt, James W.
• Assistant Examiner(s): Garcia, Alfonso
• Application Number:
  US07/289,089
• Time in Patent Office: 530 Days
• Field of Search: 365/52, 365/53, 365/60, 365/59, 365/61, 365/149, 365/145, 235/492, 235/441, 235/451, 340/825.31, 340/825.34, 340/870.37, 70/278
• US Class Current: 365/52
• CPC Class Codes: G06K 19/07745 Mounting details of integrated circuit chips
• CPC Class Codes: G06K 7/10326 the antenna being of the very-near field type, e.g. capacitive
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00
• CPC Class Codes: H05K 1/117 Pads along the edge of rigid circuit boards, e.g. for pluggable connectors
• CPC Class Codes: H05K 1/16 incorporating printed electric components, e.g. printed resistor, capacitor, inductor

Abstract

An interconnection system for transferring either electrical energy in the form of power and data signals or both is disclosed. Capacitive coupling devices are shown connected to a memory device such as an erasable programmable read only memory chip, in a form suitable for use in a smart data entry card. The capacitive coupling devices employ a dielectric medium having a relatively high dielectric constant due to the orientation of the crystals of the dielectric medium. Barium Titinate having a dielectric constant of 18,000 in the direction of the crystal axis is used. Only small bearing pressures sufficient to wipe contaminants from the exposed contact pads are required.

Claims

1. In a system for transferring intelligence, a first circuit including memory means for storing said intelligence and for effecting a readout of said intelligence, said first circuit including a plurality of contact pads interconnected to the memory means, each contact pad comprising first and second electrodes separated by an internal dielectric medium having a dielectric constant orders of magnitude greater than the dielectric constant of air, the first electrode being exposed so that the first circuit is adapted to be connected to a second circuit by electrically conductive contact means for establishing an ohmic point contact between the first and second circuit by wiping action with an exposed contact surface on one of the first and second circuits;

whereby intelligence can be capacitively transferred between the first and the second circuits, relatively small changes in voltage being detectable due to the relatively large dielectric constant of the internal dielectric medium, so that the interconnection remains substantially unaffected by dielectric materials on the exterior of the exposed contact surface.

2. The system of claim 1 wherein the internal dielectric medium has a dielectric constant on the order of 10⁴ times the dielectric constant of air.

3. The system of claim 2 wherein the internal dielectric medium comprises a piezoelectric material.

4. The system of claim 2 wherein the internal dielectric medium comprises barium titanate.

5. The system of claim 4 wherein the internal dielectric medium comprises oriented barium titanate in which the axis of barium titanate crystals is oriented orthogonally relative to the first and second electrodes.