Electromagnetic detection line digitizer

• US 4,138,592 A
• Filed: 09/16/1977
• Issued: 02/06/1979
• Est. Priority Date: 09/16/1977
• Status: Expired due to Term

• Current Assignee: David R. Mcgrew, Jack D. Capehart, John F. Mazzae
• Original Assignee: David R. Mcgrew, Jack D. Capehart, John F. Mazzae
• Inventors: McGrew, David R., Mazzae, John F., Capehart, Jack D.
• Primary Examiner(s): Robinson, Thomas A.
• Application Number:
  US05/833,778
• Time in Patent Office: 508 Days
• Field of Search: 178/19, 178/18, 178/20, 318/568, 35/61, 200/159 B, 340/146.3 SY, 346/139 C, 33/1 M, 33/1 LE
• US Class Current: 178/18.07
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A graphic curve digitizer is disclosed wherein the x-y coordinate values of a response curve (made electrically conductive) are obtained by a digitally controlled x-y conductive probe and electronic system sensing when the probe contacts the curve by the voltage signal existing in the conductive curve due to the antenna effect of the conductive curve in an environmental alternating current electromagnetic field.

Claims

1. A graphic curve digitizer for converting data from the form of an x-y plotted conductive graphical curve to digital data in x-y coordinate form;

the said conductive graphic curve being located in a normal ambient alternating current electromagnetic field and thereby having an induced voltage, the said digitizer comprising;

a. an x-y plotter having a stylus support and x-y transport mechanism for moving the said stylus support and means for receiving the said x-y plotted graphical curve;

b. a shielded electrically conductive stylus having a sensitive tip positioned in said stylus support;

c. a high impedance amplifier electrically connected to the said stylus and providing an output;

d. a comparator having a predetermined reference level electrically connected to said high impedance input amplifier and providing an output when the said output from the high impedance amplifier exceeds the said reference level; and

e. means cooperating with the said output of the comparator and the said stylus transport mechanism for advancing the said transport mechanism in x and y increments responsive to the said stylus contacting the said conductive graphical curve and providing a digitized record of the said curve.

2. A graphic curve digitizer for digitizing a curve trace on an insulative background in digital x-y coordinates comprising:

a. means for making the said graphic curve trace electrically conductive;

b. an ambient alternating current electromagnetic field generating in said conductive curve trace an induced voltage;

c. a shielded electrical conductive stylus having a voltage sensitive tip for sensing the said induced voltage;

d. an x-y plotter having a stylus transport mechanism with means for moving the said stylus in x-y coordinates and means for receiving and positioning the said tip of the said electrically conductive stylus in contact with the said insulative background;

e. a high impedance input amplifier connected to the said stylus and providing an output responsive to the said electromagnetic field induced voltage sensed by the said stylus tip;

f. an electrical comparator having a determined reference voltage and providing an output when the said tip of the conductive stylus is in contact with the said conductive curve; and

g. means cooperating with the output of the said comparator and the said stylus transport mechanism for moving the said stylus responsive to the said graphic curve and providing digital x-y coordinates of the said graphic curve.