Position detecting apparatus and driving system

Patent metadata

Field	Value
Publication number	US-9438147-B2
Application number	US-201414192268-A
Country	US
Kind code	B2
Filing date	Feb 27, 2014
Priority date	Jul 12, 2013
Publication date	Sep 6, 2016
Grant date	Sep 6, 2016

Abstract

The position detecting apparatus includes a comparing part that compares the value of the digital signal output from the AD converter and a reference value that is based on a preset reference amplitude at the timings and outputs a control signal responsive to a result of the comparison. The position detecting apparatus includes an amplitude controlling part that controls amplification factors of the first amplifier and the second amplifier in such a manner that the value of the digital signal output from the AD converter comes closer to the reference value in response to the control signal output from the comparing part.

First claim

What is claimed is:

1. A position detecting apparatus comprises:
a sensor that outputs two position detection signals with different phases that vary with a same amplitude and a same period in response to a relative movement with respect to a scale;
a first amplifier that outputs a first amplified signal obtained by amplifying an amplitude of a first position detection signal with a first phase of the position detection signals and a first inverted signal obtained by inverting the first amplified signal;
a second amplifier that outputs a second amplified signal obtained by amplifying an amplitude of a second position detection signal with a second phase of the position detection signals and a second inverted signal obtained by inverting the second amplified signal;
a first comparator that compares the first amplified signal and the second amplified signal and outputs a first comparison signal responsive to a result of the comparison;
a second comparator that compares the first amplified signal and the second inverted signal and outputs a second comparison signal responsive to a result of the comparison;
a phase angle measuring part that measures phase angles of the position detection signals with respect to a reference position, outputs a selection signal that prescribes which one of the first amplified signal, the second amplified signal, the first inverted signal and the second inverted signal should be selected, and outputs a timing signal that prescribes timings at which two of the first amplified signal, the second amplified signal, the first inverted signal and the second inverted signal intersect with each other;
an AD converter that receives the first amplified signal, the second amplified signal, the first inverted signal and the second inverted signal, continuously reads a value of a signal selected according to the selection signal from among the first amplified signal, the second amplified signal, the first inverted signal and the second inverted signal, and outputs a digital signal responsive to the read value;
a comparing part that compares the value of the digital signal output from the AD converter and a reference value that is based on a preset reference amplitude at the timings and outputs a control signal responsive to a result of the comparison; and
an amplitude controlling part that controls amplification factors of the first amplifier and the second amplifier in such a manner that the value of the digital signal output from the AD converter comes closer to the reference value in response to the control signal output from the comparing part.

2. The position detecting apparatus according to claim 1 , wherein a phase difference between the first position detection signal and the second position detection signal is 90 degrees.

3. The position detecting apparatus according to claim 2 , wherein the timing signal prescribes a first timing at which a voltage of the first amplified signal becomes equal to or higher than a voltage of the second amplified signal, a second timing at which a voltage of the second inverted signal becomes equal to or higher than the voltage of the first amplified signal, a third timing at which the voltage of the first amplified signal becomes lower than the voltage of the second amplified signal, and a fourth timing at which the voltage of the second inverted signal becomes lower than the voltage of the first amplified signal, and
the comparing part compares the value of the digital signal output from the AD converter and the reference value at the first to fourth timings prescribed by the timing signal.

4. The position detecting apparatus according to claim 2 , wherein the phase angle measuring part
outputs the selection signal that prescribes to select the second inverted signal in a case where the voltage of the first amplified signal is equal to or higher than the voltage of the second amplified signal, and the voltage of the second inverted signal is lower than the first amplified signal,
outputs the selection signal that prescribes to select the first inverted signal in a case where the voltage of the first amplified signal is equal to or higher than the voltage of the second amplified signal, and the voltage of the second inverted signal is equal to or higher than the first amplified signal,
outputs the selection signal that prescribes to select the second amplified signal in a case where the voltage of the first amplified signal is lower than the voltage of the second amplified signal, and the voltage of the second inverted signal is equal to or higher than the first amplified signal, and
outputs the selection signal that prescribes to select the first amplified signal in a case where the voltage of the first amplified signal is lower than the voltage of the second amplified signal, and the voltage of the second inverted signal is lower than the first amplified signal.

5. The position detecting apparatus according to claim 1 , wherein the amplitude controlling part
decreases the amplification factors of the first amplifier and the second amplifier in a case where the value of the digital signal is higher than the reference value, and
increases the amplification factors of the first amplifier and the second amplifier in a case where the value of the digital signal is lower than the reference value.

6. The position detecting apparatus according to claim 1 , wherein the timing signal prescribes a first timing at which a voltage of the first amplified signal becomes equal to or higher than a voltage of the second amplified signal, a second timing at which a voltage of the second inverted signal becomes equal to or higher than the voltage of the first amplified signal, a third timing at which the voltage of the first amplified signal becomes lower than the voltage of the second amplified signal, and a fourth timing at which the voltage of the second inverted signal becomes lower than the voltage of the first amplified signal, and
the comparing part compares the value of the digital signal output from the AD converter and the reference value at the first to fourth timings prescribed by the timing signal.

7. The position detecting apparatus according to claim 1 , wherein the phase angle measuring part
outputs the selection signal that prescribes to select the second inverted signal in a case where the voltage of the first amplified signal is equal to or higher than the voltage of the second amplified signal, and the voltage of the second inverted signal is lower than the first amplified signal,
outputs the selection signal that prescribes to select the first inverted signal in a case where the voltage of the first amplified signal is equal to or higher than the voltage of the second amplified signal, and the voltage of the second inverted signal is equal to or higher than the first amplified signal,
outputs the selection signal that prescribes to select the second amplified signal in a case where the voltage of the first amplified signal is lower than the voltage of the second amplified signal, and the voltage of the second inverted signal is equal to or higher than the first amplified signal, and
outputs the selection signal that prescribes to select the first amplified signal in a case where the voltage of the first amplified signal is lower than the voltage of the second amplified signal, and the voltage of the second inverted signal is lower than the first amplified signal.

8. The position detecting apparatus according to claim 1 , wherein the first comparator
receives the first amplified signal at a non-inverting input terminal thereof and the second amplified signal at an inverting input terminal thereof and outputs the first comparison signal at an output thereof, and
the second comparator

Assignees

• Toshiba Kk

Inventors

• Ariga Hiroshi
• Inoue Masahiro

Classifications

• G01D5/2448

  Correction of gain, threshold, offset or phase control · CPC title

• H02P6/16

  Circuit arrangements for detecting position · CPC title

• H02P6/006 Primary

  Controlling linear motors · CPC title