GRAPHIC DATA TRANSCRIPTION SYSTEM

• US 3,632,874 A
• Filed: 12/29/1969
• Issued: 01/04/1972
• Est. Priority Date: 12/31/1968
• Status: Expired due to Term

• Current Assignee: Lucien C. Malavard, Pierre M. Marty
• Original Assignee: Lucien C. Malavard, Pierre M. Marty
• Inventors: Malavard, Lucien C., Marty, Pierre M.
• Primary Examiner(s): Claffy, Kathleen H.
• Assistant Examiner(s): Brauner, Horst F.
• Application Number:
  US04/888,381
• Time in Patent Office: 736 Days
• Field of Search: 178/18,19,20
• US Class Current: 178/18.01
• CPC Class Codes: G06F 2203/04113 Peripheral electrode pattern in resistive digitisers, i.e. electrodes at the periphery of the resistive sheet are shaped in patterns enhancing linearity of induced field
• CPC Class Codes: G06F 3/045 using resistive elements, e.g. a single continuous surface or two parallel surfaces put in contact
• CPC Class Codes: G06K 15/22 using plotters
• CPC Class Codes: G09G 1/12 the deflection signals being produced by essentially analogue means

Abstract

Graphic data transcription apparatus comprising a writing plate made of an electrically resisting medium and having a given shape, two sets of terminals arranged along the periphery of said plate, means for alternately and rhythmically applying to one and the other of said sets biasing voltages to sequentially produce at a given frequency two mutually orthogonal electric fields in said medium, the terminals in each one of said sets being alternately interconnected and insulated from each other, a conductive point probe in bearing contact with and movable on the writing plate surface, and means for using the voltage alternately developed between said probe and a point at a fixed reference potential to visually reproduce on a receiver the geometric track followed by said probe on said surface. In the case of a rectangular writing plate, the ratio of the width of the terminals in each one of said sets to their mutual spacing is preferably comprised between one and two.

Claims

1. A graphic data transcription apparatus comprising a writing plate made of an electrically resistant material having a given shape, two pairs of equipotential electrodes each comprising two elements, at least one series of peripheral conductive terminals spaced from one another and each in contact with the writing plate and distributed along a line near the writing-plate periphery;

means for applying a constant biasing voltage supplied between two fixed potential points alternately and periodically at a selected repetition frequency between the two elements of one and the other electrode pair, such voltage raising the potential of each of said two elements to a given value relatively to a reference-potential point;

switching and connecting means controLled by a control signal generator to alternately and periodically connect at least part of such terminals to said electrode pairs and to produce an electric field on the surface of the writing plate, said series of terminals and said connection means being so disposed that electric fields produced thereby on the writing-plate surface when said series of terminals are consecutively connected to one and the other of said electrode pairs are at right angles to one another;

a conductive point probe in bearing contact with and movable on the writing-plate surface; and

means using the voltages developed alternately at said frequency between said probe and said reference-potential point to reproduce visually on a receiver the geometric track followed by the probe in its movement on the writing-plate surface, on the basis of the values of the alternately produced voltages and respectively representing the analog values of the two components of a selected geometric coordinates system on the writing-plate surface, said peripheral terminal series being so arranged that the ratio of terminal width measured along the line portion along which said terminals are disposed to the spacing between two consecutive terminals is comprised between one and three; and

the resistant plate being in contact with each terminal only by way of a very small fraction of the latter terminal surface.

2. Apparatus as set forth in claim 1, in which the operative surface of the resistant plate is of rectangular shape and in which two series of terminals are respectively disposed one along each pair of opposite sides of the rectangular periphery of the plate, each such series also forming one of the electrode pairs, when all terminals thereof are connected by direct connections to one of said fixed potential points.

3. Apparatus as set forth in claim 1, in which the operative surface of the resistant plate is of circular shape and in which all the peripheral terminals are disposed on a circle forming the outline of the operative surface, the two elements of each electrode pair between which said constant biasing voltage is applied being composed of sets of terminals arranged along straight lines disposed around said circle and being connected alternately to all the terminals so as to impart to each terminal a potential which is a function of the angular position of such terminal, through the agency of resistors of appropriate values energized from said electrodes, the distribution of the said resistors at any particular time differing according to which of the electrode pairs is the one which is biased at said particular time.

4. Apparatus as set forth in claim 3, in which the various potentials required for the peripheral terminals are produced by a device comprising two auxiliary electrode pairs each comprising a further series of terminals disposed on a fraction of a circle and energized alternately at a constant potential, an auxiliary system of terminals arranged in a circle, an auxiliary resistant plate in electrical contact with the two auxiliary pairs and with said auxiliary system, and a direct connection between each of the terminals of said auxiliary system and a corresponding one of the peripheral terminals arranged in a circle on the outline of the resistant plate.

5. Apparatus as set forth in claim 1, using polar coordinates, in which one of the electrode pairs consists of two further series of terminals disposed on two radii of a circle and the other electrode pair comprises as one of its elements terminals distributed around the periphery of such circle and constituting at the same time said peripheral terminals and as its other element a terminal disposed at the center of said circle.