APPARATUS FOR CAPACITIVELY SENSING INFORMATION APERTURES IN DATA CARDS

• US 3,585,368 A
• Filed: 08/08/1969
• Issued: 06/15/1971
• Est. Priority Date: 08/08/1969
• Status: Expired due to Term

• Current Assignee: Thomas A. Nunamaker
• Original Assignee: Thomas A. Nunamaker
• Inventors: Nunamaker, Thomas A.
• Application Number:
  US04/848,550
• Time in Patent Office: 676 Days
• US Class Current: 235/451
• CPC Class Codes: G06K 7/081 electrostatic, e.g. by detecting the charge of capacitance between electrodes

Abstract

Card reading apparatus comprising a plurality of input conductors for disposition along one side of a data card incorporating an electric shield and a plurality of readout conductors for disposition along the opposite side of the card to establish a capacitive coupling between the readout conductors and the input conductors through selectively positioned apertures in the shield representing recorded information. A plurality of voltage stabilizing capacitors have output sides connected to the respective readout conductors. A plurality of voltage stabilizing amplifiers have inputs connected to the respective readout conductors and outputs connected to the input sides of the respective capacitors. Information receiving means is coupled to the input side of each capacitor to respond to the change in voltage applied thereto by the corresponding amplifier upon energization of an input conductor to which the corresponding readout conductor is coupled capacitively through an aperture in the electric shield. The capacitance of each capacitor and the gain of each amplifier operate together in response to an incipient change in voltage on the corresponding readout conductor to restore continuously the original voltage on the conductor so that the input to the information receiving means is not rendered inaccurate by spurious and parasitic capacitive relationships of the readout conductors to adjacent structure.

Claims

1. Apparatus for reading data cards incorporating an electric shield apertured selectively in a pattern representing recorded information, said apparatus comprising, in combination, a plurality of input conductors disposed generally in mutually parallel spaced relation to each other for disposition along one side of a card to be read, means for applying a voltage to the individual input conductors selectively, a plurality of readout conductors disposed generally in mutually parallel spaced relation to each other for disposition along the opposite side of the card to be read, said readout conductors being oriented in a generally transverse cross relation to said input conductors and being disposed in spaced relation to the latter to provide therebetween data card space and to provide between each input conductor and each readout conductor a capacitive coupling that is subject to blocking by an intervening conductive shield of a data card in said space, a plurality of voltage stabilizing capacitors corresponding to said respective readout conductors, each of said voltage stabilizing capacitors having an input side and an output side, the output side of each voltage stabilizing capacitor being connected t the corresponding readout conductor, a plurality of voltage stabilizing amplifiers corresponding to the respective readout conductors and being high gain voltage amplifiers with high input impedance, each of said voltage stabilizing amplifiers having its input connected to the corresponding readout conductor and having its output connected to the input side of the corresponding voltage stabilizing capacitor, the voltage stabilizing amplifier and the voltage stabilizing capacitor connected to each readout conductor having respectively a gain and a capacitance mutually related to each other to effect in response to an incipient change in voltage on the corresponding readout conductor a restoration of the original voltage on the readout conductor by a flow of electrical charge between the capacitor and the readout conductor induced by an amplified change in voltage applied by the amplifier to the input side of the capacitor so that the voltage on the readout conductor remains substantially unchanged by the energization of anY of said input conductors to which the readout conductor is capacitively coupled through an aperture in the electrical shield interposed therebetween, and information-receiving means coupled to said input side of each of said voltage stabilizing capacitors to respond to the change of voltage applied to said input side of the capacitor by the corresponding voltage stabilizing amplifier as an incident to energization of an input conductor to which the corresponding readout conductor is coupled capacitively through an aperture in an intervening electrical shield.

2. Apparatus for reading a data storage element incorporating an electric shield apertured selectively in a pattern representing recorded information, said apparatus comprising, in combination, a plurality of input conductors for disposition along one side of a data storage element to be read, means for energizing said input conductors selectively, a plurality of readout conductors for disposition along the opposite side of the data storage element to be read to provide between individual input conductors and individual readout conductors capacitive couplings that are subject to blocking by a data storage element intervening between the input conductors and the readout conductors and incorporating an electric shield defining selectively positioned apertures providing for unblocked capacitive coupling therethrough of individual input conductors with individual readout conductors, a plurality of voltage stabilizing capacitors corresponding to said respective readout conductors, each of said voltage stabilizing capacitors having an input side and an output side, the output side of each voltage stabilizing capacitor being coupled to the corresponding readout conductor, a plurality of voltage stabilizing amplifiers corresponding to the respective readout conductors, each of said voltage stabilizing amplifiers having its input coupled to the corresponding readout conductor and having its output coupled to the input side of the corresponding voltage stabilizing capacitor, the voltage stabilizing amplifier and the voltage stabilizing capacitor corresponding to each readout conductor having respectively a gain and a capacitance mutually related to each other to effect in response to an incipient change in voltage on the corresponding readout conductor a substantial restoration of the original voltage on the readout conductor by a flow of electrical charge between the capacitor and the readout conductor induced by a change in voltage applied by the amplifier to the input side of the capacitor as an incident to the energization of any of said input conductors to which the readout conductor is capacitively coupled through an aperture in the electrical shield disposed therebetween and information-receiving means coupled to said input side of each of said voltage stabilizing capacitors to respond to the change of voltage applied to said input side of the capacitor by the corresponding voltage stabilizing amplifier as an incident to energization of an input conductor to which the corresponding readout conductor is coupled capacitively through an aperture in an intervening electrical shield.

3. Apparatus for reading a data storage element incorporating an electric shield apertured selectively in a pattern representing recorded information, said apparatus comprising, in combination, a plurality of energizable input conductors for disposition alongside a data storage element to be read, a plurality of readout conductors for disposition alongside the data storage element to provide between the input conductors and the readout conductors capacitive couplings that are subject to blocking by an intervening data storage element incorporating an electric shield defining selectively positioned apertures providing selectively for unblocked capacitive coupling therethrough of individual input conductors with individual readout conductors, a plurality of voltage stabilizing capacitors having outputs coupled with said respective readout conDuctors, a plurality of voltage stabilizing amplifiers having inputs coupled with said respective readout conductors and having outputs coupled to inputs of the corresponding voltage stabilizing capacitors, the voltage stabilizing amplifier and the voltage stabilizing capacitor corresponding to each readout conductor having respectively a gain and a capacitance mutually related to each other to effect as an incident to the energization of any of said input conductors to which the readout conductor is capacitively coupled through a shield aperture a substantial restoration of the original voltage on the readout conductor by a flow of electrical charge between the capacitor and the readout conductor induced by a change in voltage applied by the amplifier to the capacitor, and information-receiving means coupled to respond to the change of voltage applied to said respective voltage stabilizing capacitors by the corresponding voltage stabilizing amplifiers as an incident to energization of individual input conductors to which the readout conductors are coupled capacitively through shield apertures.