Non-contact type potentiometer employing a triangular wave encoder

• US 4,978,954 A
• Filed: 04/10/1989
• Issued: 12/18/1990
• Est. Priority Date: 12/01/1988
• Status: Expired due to Fees

• Current Assignee: Tamagawa Seiki Kabushiki Kaisha
• Original Assignee: Tamagawa Seiki Kabushiki Kaisha
• Inventors: Koike, Kazumasa
• Primary Examiner(s): Miska, Vit W.
• Application Number:
  US07/335,597
• Time in Patent Office: 617 Days
• Field of Search: 341/1, 341/11, 341/13, 341/15
• US Class Current: 341/1
• CPC Class Codes: H03M 1/202 by interpolation
• CPC Class Codes: H03M 1/303 Circuits or methods for processing the quadrature signals

Abstract

A non-contact type potentiometer employing a triangular wave encoder includes a triangular wave encoder for outputting a triangular wave signal consisting of a LEAD signal and a LAG signal having the phases different from each other. A pair of comparators are provided for waveforming the triangular wave signals into a pair of rectangular wave signals. An up/down signal converter is provided for converting each of the rectangular wave signals into up/down directive pulses, and an up/down counter is provided for receiving the directive pulses and outputting an absolute digital signal which is supplied to a D/A converter for converting the absolute digital signal into analog position step signals. An analog switch control circuit having a first switch and a second switch and supplied with the LEAD signal and a LEAD signal inverted from the LEAD signal is also turned on or off by being supplied with the rectuangular wave signals B obtained from the LAG signal and a rectangular wave signal B inverted from the rectangular wave signal B. An operational amplifier is provided for summing together the output signal from the analog switch control circuit and the analog position step signal. The above switches are controlled responsive to the high level of the rectangular wave signals to supple the LEAD signal or the LEAD signal to be summed with the analog position step signal to produce a linear analog potentiometer output signal from the operational amplifier.

Claims

1. A non-contact type potentiometer making use of a triangular wave encoder comprising

a triangular wave encoder for outputting a triangular wave signal consisting of a LEAD signal and a LAG signal having phases different from each other, first and second comparators for waveforming respectively said LEAD and LAG triangular wave signals into a corresponding pair of rectangular wave signals A and B, and up/down signal converter for converting each of said rectangular wave signals into up/down directive pulses, an up/down counter for receiving said directive pulses and outputting an absolute digital signal, a D/A converter for converting said absolute digital signal into an analog position step signal, an analog switch control circuit having a first switch and a second switch coupled respectively to be supplied with said LEAD signal and with a LEAD signal inverted from said LEAD signal while being coupled to an output of said second comparator to be turned on or off by being supplied with both said rectangular wave signal B obtained from said LAG signal and with a rectangular wave signal B inverted from said rectangular wave signal B, and an operational amplifier for summing together the output signal from said analog switch control circuit and said analog position step signal, wherein said switches are controlled responsive to the high level of said rectangular wave signals B and B to control said switches to supply said LEAD signal or said LEAD signal to be summed with said analog position step signal to produce a linear analog potentiometer output signal from said operational amplifier.