ELECTRICAL INSCRIBING

• US 3,624,293 A
• Filed: 03/19/1970
• Issued: 11/30/1971
• Est. Priority Date: 03/19/1970
• Status: Expired due to Term

• Current Assignee: Larry K. Baxter
• Original Assignee: Larry K. Baxter
• Inventors: Baxter, Larry K.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Brauner, Horst F.
• Application Number:
  US05/021,156
• Time in Patent Office: 621 Days
• Field of Search: 178/18,19,20
• US Class Current: 178/20.04
• CPC Class Codes: G06F 3/044 by capacitive means
• CPC Class Codes: G06F 3/0441 using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals

Abstract

An electrical inscribing system comprises a set of parallel resistance wires orthogonal to and insulatedly separated from another set of parallel resistance wires. The X set of wires is connected between left and right conducting strips. The Y set of wires is connected between top and bottom conducting strips. Signals in time quadrature are applied between the top and bottom strips and then to the left and right strips. The X set and Y set of wires are separated by a 1/2 -mil plastic insulating film. A 1/4 -inch sheet of plexiglass covers the upper set and may function as a writing surface. An electronic pen may be moved along the plexiglass and is AC coupled to the grid of resistance wires to provide an output signal from its self-contained preamplifier that is representative of the X and Y coordinates of the penpoint.

Claims

1. Electronic tablet means comprising, first, second, third and fourth conductors, a first set of generally parallel resistive wires connected between said first and second conductors, a second set of generally parallel resistive wires connected between said third and fourth conductors othogonal to said first set, and an insulating means disposed intermediate said first and second sets for insulatedly separating said sets, the resistance of each of said resistive wires being high compared to that of each of said conductors.

2. An electronic inscribing tablet in accordance with claim 1 wherein the insulating layer between said two sets of wires is smaller in thickness than the separation between adjaceNt parallel resistive wires in a set.

3. An electronic inscribing tablet in accordance with claim 2 wherein said insulating layer has a thickness of the order of 1/2 mil between said two sets of wires.

4. An electronic inscribing tablet in accordance with claim 2 and further comprising an insulating sheet overlaying the grid formed by said first and second sets to comprise a convenient writing surface.

5. An electronic inscribing tablet in accordance with claim 1 and further comprising a source of signals of the same frequency substantially in time quadrature, and means for coupling said time quadrature signals to respective ones of the conductors associated with a set so that the phase of the signal along a resistive wire in a set is directly proportional to the associated coordinate.

6. An electronic inscribing tablet in accordance with claim 5 and further comprising, means for first coupling said time quadrature signals to said first and second conductors and then to said third and fourth conductors to provide orthogonal components of a position-indicative signal during mutually exclusive alternating substantially contiguous time intervals.

7. Electrographic apparatus comprising:

a first pair of elongated conductors with each spaced one from the other, a second pair of elongated conductors with each spaced one from the other, said first and second pairs being disposed in a quadrilateral arrangement with the first pair of conductors insulatedly separated from the second pair of conductors, a first set of generally parallel resistive wires connected between said first pair of elongated conductors and defining a first plane, a second set of generally parallel resistive wires connected between said second pair of elongated conductors and defining a second plane, said first set of generally parallel resistive wires being orthogonal to said second set, and an insulating means disposed intermediate said first and second sets for insulatedly separating said sets, said first and second sets being disposed so that said first and second planes are substantially parallel, each said resistive wire having a resistance that is high in comparison to each of said elongated conductors of said pairs of conductors.