Encoder and signal adjustment method for the same

• US 7,116,252 B2
• Filed: 06/14/2005
• Issued: 10/03/2006
• Est. Priority Date: 06/21/2004
• Status: Active Grant

• Current Assignee: Mitutoyo Corporation
• Original Assignee: Mitutoyo Corporation
• Inventors: Teraguchi, Mikiya
• Primary Examiner(s): JEAN PIERRE, PEGUY
• Application Number:
  US11/151,286
• Publication Number:
  US 20050280563A1
• Time in Patent Office: 476 Days
• Field of Search: 341/11, 341/6, 341/118, 341/155, 702/189
• US Class Current: 341/118
• CPC Class Codes: G01D 18/001 Calibrating encoders
• CPC Class Codes: G01D 5/24409 Interpolation using memories
• CPC Class Codes: G01D 5/2448 Correction of gain, threshold, offset or phase control
• CPC Class Codes: G01D 5/2449 using hard-stored calibration data

Abstract

An encoder includes: a detector; an A/D converter for performing A/D conversion for a two-phase analog signal output from the detector; an error correction circuit for correcting an error of the two-phase analog signal; an interpolation circuit for performing interpolation from the corrected result of A/D conversion; a memory for storing correction data; and a central processing unit (CPU) having communication means. The result of A/D conversion of the two-phase analog signal is sent by the communication means to an external personal computer. The error of sine and cosine signals from a predetermined value is detected by the personal computer and is sent by the communication means. The encoder performs interpolation in which the error is corrected by using the received correction data. Thus, it is possible to perform signal adjustment without observing a display screen of an oscilloscope, while confirming a status of signal adjustment in a non-stepped manner. This enables optimum adjustment and confirmation to be performed, and reduces an interpolation error caused by adjustment of the encoder signal.

Claims

1. An encoder comprising:

a detector;

means for performing A/D conversion for an analog signal having at least two phases, the signal being output from the detector;

means for correcting an error of the analog signal after A/D conversion;

an interpolation circuit for performing interpolation from a result of A/D conversion of the analog signal that is corrected;

means for storing correction data; and

central processing units having communication means with an external device for sending the result of A/D conversion data to the external device, receiving an error of the signal from the external device and storing the error as the correction data.

2. The encoder according to claim 1, further comprising means for displaying an abnormal state during signal adjustment.

3. A method for adjusting a signal of an encoder, the encoder comprising:

a detector;

means for performing A/D conversion for an analog signal having at least two phases, the signal being output from the detector;

means for correcting an error of the analog signal after A/D conversion;

an interpolation circuit for performing interpolation from a result of A/D conversion of the analog signal that is corrected;

means for storing correction data; and

central processing units having communication means with an external device, the method comprising the steps of;

sending the result of A/D conversion of the analog signal to the external device by the communication means;

allowing the external device to detect the error of the signal from a predetermined value and to send the error to the encoder by the communication means; and

allowing the encoder to perform interpolation for which error correction is performed by using the received correction data.

4. The method for adjusting a signal of an encoder according to claim 3, wherein

the analog signal is a two-phase signal converted from a three-phase signal.

5. The method for adjusting a signal of an encoder according to claim 3, wherein

the external device is a personal computer.

6. The method for adjusting a signal of an encoder according to claim 3, wherein

the signal transmitted from the encoder and a waveform for which the error is corrected are displayed on the external device.

7. The method for adjusting a signal of an encoder according to claim 3, wherein

the signal adjustment is achieved by mechanically adjusting a position of the detector or adjusting a gain of an amplifier provided in the detector when an amplitude of the signal is insufficient;

and

then adjusting the signal while scanning the detector.

8. The method for adjusting a signal of an encoder according to claim 3, wherein

a message indicating a communication error is displayed when no communication is performed.

9. An encoder comprising:

a detector;

means for performing A/D conversion for an analog signal having at least two phases, the analog signal being output from the detector;

means for detecting an error of the analog signal;

means for correcting the error of the analog signal after A/D conversion;

an interpolation circuit for performing interpolation from a result of A/D conversion of the analog signal that is corrected;

means for storing correction data; and

central processing units having communication means with an external device for sending the error of the signal to the external device for displaying and determining a corrected signal.

10. The encoder according to claim 9, further comprising means for displaying a status of adjustment.

11. A method for adjusting a signal of an encoder, the encoder comprising:

a detector;

means for performing A/D conversion for an analog signal having at least two phases, the analog signal being output from the detector;

means for detecting an error of the analog signal;

means for correcting the error of the analog signal after A/D conversion;

an interpolation circuit for performing interpolation from a result of A/D conversion of the analog signal that is corrected;

means for storing correction data; and

central processing units having communication means with an external device, the method comprising the steps of;

sending the result of A/D conversion of the analog signal after correction to the external device; and

allowing the external device to display and determine the corrected signal.

12. The method for adjusting a signal of an encoder according to claim 11, wherein

the analog signal is a two-phase signal converted from a three-phase signal.

13. The method for adjusting a signal of an encoder according to claim 11, wherein

the external device is a personal computer.

14. The method for adjusting a signal of an encoder according to claim 11, wherein

the signal transmitted from the encoder and a waveform for which the error is corrected are displayed on the external device.

15. The method for adjusting a signal of an encoder according to claim 11, wherein

the signal adjustment is achieved by mechanically adjusting a position of the detector or adjusting a gain of an amplifier provided in the detector when an amplitude of the signal is insufficient;

and

then adjusting the signal while scanning the detector.

16. The method for adjusting a signal of an encoder according to claim 11, wherein

a message indicating a communication error is displayed when no communication is performed.