Coordinate reader

• US 4,672,155 A
• Filed: 01/02/1986
• Issued: 06/09/1987
• Est. Priority Date: 01/14/1985
• Status: Expired due to Fees

• Current Assignee: Naruse, Makoto
• Original Assignee: Naruse, Makoto
• Inventors: Naruse, Makoto
• Primary Examiner(s): SCHREYER, STAFFORD
• Application Number:
  US06/815,705
• Time in Patent Office: 523 Days
• Field of Search: 178/18, 178/19, 178/20, 340/870.31, 323/212, 323/218, 324/239, 318/687
• US Class Current: 178/18.07
• CPC Class Codes: G06F 3/046 by electromagnetic means

Abstract

A coordinate reader comprises first and second conductor loops each having an electrical conductor so that electrical conductors of the respective conductor loops are juxtaposed on an electrically insulating board, a cosine function generator connected to one of the first and second conductor loops, a sine function generator connected to the other of the first and second conductor loops, a cursor incorporating a magnetic flux detecting coil for detecting magnetic fluxes generated in the conductor loops excited by the cosine and sine function generators, and a processor. The processor processes and controls operations of the aforementioned components to detect coordinates of the cursor.

Claims

1. A coordinate reader comprising:

an electrically insulating board;

a pair of first and second conductor loops each having an electrical conductor alternately folded at a period P so that the electrical conductors of the respective conductor loops are juxtaposed on said electrically insulating board;

cosine function generating means, connected to one of said first and second conductor loops, for generating an output voltage whose amplitude oscillates in the form of a cosine function of a variable α

, where the variable α

is representative of a distance from an origin in one of a plurality of periodic regions respectively defined by the electrical conductor of said first or second conductor loop folded alternately at the period P;

sine function generating means, connected to the other of said first and second conductor loops, for generating an output voltage whose amplitude oscillates in the form of a sine function of the variable α

;

a cursor incorporating a magnetic flux detecting coil for detecting magnetic fluxes generated in said conductor loops excited by said cosine function generating means and sine function generating means;

processing means for setting the period P and the variable α

in said cosine function generating means and said sine function generating means, increasing or decreasing the variable α

in predetermined incremental or decremental unit to excite said first and second conductor loops to thereby generate an induced voltage in said cursor, and detecting a value of the variable α

as coordinate of said cursor within one periodic region when the phase of the induced voltage is inverted, and

a plurality of current switches are each connected to respective alternate folding points of said electrical conductor of each of said first and second conductor loops, a predetermined value is added to or subtracted from coordinates of said cursor which have been detected within one periodic region so as to provide a value of the variable α

, this value of the variable α

is set in said cosine function generating means and said sine function generating means to excite said first and second conductor loops, and the number of periodic regions to be excited is increased or decreased by sequentially switching the plurality of current switches.

2. A coordinate reader comprising:

an electrically insulating board;

a pair of first and second conductor loops each having an electrical conductor alternately folded at a period P so that the electrical conductor of the respective conductor loops are juxtaposed on said electrically insulating board;

cosine function generating means, connected to one of said first and second conductor loops, for generating an output voltage whose amplitude oscillates in the form of a cosine function of a variable α

, where the variable α

is representative of a distance from an origin in one of a plurality of periodic regions respectively defined by the electrical conductor of said first or second conductor loop folded alternately at the period P;

sine function generating means, connected to the other of said first and second conductor loops, for generating an output voltage whose amplitude oscillates in the form of a sine function of the variable α

;

a cursor incorporating a magnetic flux detecting coil for detecting magnetic fluxes generated in said conductor loops excited by said cosine function generating means and sine function generating means;

processing means for setting the period P and the variable α

in said cosine function generating means and said sine function generating means, increasing or decreasing the variable α

in predetermined incremental or decremental unit to excite said first and second conductor loops to thereby generate an induced voltage in said cursor, and detecting a value of the variable α

as coordinate of said cursor within one periodic region when the phase of the induced voltage is inverted, and

the output voltages of said cosine function generating means and said sine function generating means are added with a DC voltage of a level which is more than half the maximum amplitude of those output voltages.