Method and apparatus for detecting a rotation angle

• US 5,012,673 A
• Filed: 04/01/1988
• Issued: 05/07/1991
• Est. Priority Date: 04/03/1987
• Status: Expired due to Term

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Takano, Yoshiya, Hoshi, Yoshikazu
• Primary Examiner(s): Myracle, Jerry W.
• Application Number:
  US07/176,087
• Time in Patent Office: 1,131 Days
• Field of Search: 377/2, 377/19, 377/17, 377/26, 377/45, 307/309, 307/514, 307/515, 307/516, 73/118.1, 250/231 SE
• US Class Current: 73/114.36
• CPC Class Codes: G01D 5/2455 with incremental and absolute tracks on the same encoder
• CPC Class Codes: H03M 1/143 in pattern-reading type converters, e.g. having both absolute and incremental tracks on one disc or strip H03M1/16 takes precedence
• CPC Class Codes: H03M 1/285 of the unit Hamming distance type, e.g. Gray code
• CPC Class Codes: H03M 1/30 incremental

Abstract

A measurement range is divided into a plurality of sections, a binary coded signal is generated at each division point, small section signals are generated at a predetermined interval between the binary coded signals, the binary coded signals are weighted by angles, and the small section signals are added or subtracted to or from the weighted signal to interpolate between two binary coded signals. Since the increment signals generated between the adjacent absolute signals is used as an interpolation signal between the absolute signals, the measurement accuracy is enhanced without increasing the number of elements for generating the absolute signals. The measured angle can be accurately read by adding or subtracting the increment signals to and from the weighted signal of the absolute signal.

Claims

1. An angle detector for producing an absolute signal representing a rotation angle of a rotor, comprising:

means for generating a plurality of absolute signals in a measurement range with at least one of said plurality of absolute signals representing at least one specific angle, wherein the interval of the absolute signals in a specific measurement range is smaller than in another measurement range;

means for sequentially generating increment signals at a predetermined interval in accordance with the rotation of the rotor in measurement ranges above and below the specific angle; and

means for adding or subtracting the increment signals to or from the at least one absolute signal representing said specific angle to produce the absolute signal representing the rotation angle of the rotor.

2. An angle detector for producing an absolute signal representing a rotation angle of a rotor, comprising:

means for generating a plurality of absolute signals in a measurement range with at least one of said plurality of absolute signals representing at least one specific angle and being generated near an initial position of the rotor, wherein the interval of the absolute signals in a specific measurement range is smaller than in another measurement range;

means for sequentially generating increment signals at a predetermined interval in accordance with the rotation of the rotor in measurement ranges above and below the specific angle; and

means for adding or subtracting the increment signals to or from the at least one absolute signal representing said specific angle to produce the absolute signal representing the rotation angle of the rotor.

3. An angle detector for producing an absolute signal representing a rotation angle of a rotor, comprising:

means for generating an absolute signal representing at least one specific angle in a measurement range;

means for discriminating a direction of rotation of the rotor;

means for generating increment signals at a predetermined interval in accordance with the rotation of the rotor over the measurement range; and

means for adding or subtracting the increment signals to or from the absolute signal representing said specific angle depending on the direction of rotation discriminated by said discrimination means to correct the absolute signal.

4. An angle detector according to claim 3, wherein said corrected absolute signal represents the rotation angle of the rotor and said corrected absolute signal is continuously produced regardless of the position of said rotor.

5. An angle detector for producing an absolute signal representing a rotation angle of a rotor, comprising:

means for generating an absolute signal representing at least one specific angle in a measurement range;

means for sequentially generating increment signals at a predetermined interval in accordance with the rotation of the rotor in measurement ranges above and below the specific angle; and

means for adding or subtracting the increment signals to or from the absolute signal representing said specific angle to produce the absolute signal representing the rotation angle of the rotor, wherein said absolute signal representing the rotation angle of the rotor is continuosly produced regardless of the position of said rotor.

6. An angle detector for producing an absolute signal representing a rotation angle of a rotor, comprising:

means for generating a binary coded signal representing at least one specific angle in a measurement range;

means for sequentially generating increment signals at a predetermined interval in accordance with the rotation of the rotor in measurement ranges above and below the specific angle;

means for counting the number of increment signals;

means for adding or subtracting the count of the increment signals to or from the binary coded signal; and

means for producing the sum or difference signal as a binary coded signal representing the absolute value of the rotation angle of the rotor, wherein said binary coded signal representing the absolute value of the rotation angle of the rotor is continuously reproduced regardless of the position of said rotor.

7. An angle detector for detecting a rotation angle of a rotor, comprising:

means for generating a binary coded signal at each of division points in a measurement range;

means for generating small section signals at a predetermined interval between specific binary coded signals;

means for weighting the binary coded signal by angles; and

means for adding or subtracting the small section signals to or from the weighted signal to produce an absolute signal which interpolates two binary coded signals, wherein said absolute signal which interpolates two binary coded signals represents the rotation angle of the rotor and is continuously produced regardless of the position of said rotor.

8. An angle detector for producing an absolute signal representing a rotation angle of a rotor, comprising:

means for generating an absolute signal representing at least one specific angle in a measurement range;

means for sequentially generating increment signals at a predetermined interval in accordance with the rotation of the rotor in measurement ranges above and below the specific angle; and

means for adding or subtracting the increment signals to or from the absolute signal representing said specific angle to produce the absolute signal representing the rotation angle of the rotor, wherein a plurality of absolute signals are generated in the measurement range, each said absolute signal corresponding to a different section of the measurement range, whereby the interval of the absolute signal in a specific section of said measurement range is smaller than that in any other section of said measurement range.

9. An angle detector for producing an absolute representing a rotation angle of a rotor, comprising:

means for generating an absolute signal representing at least one specific angle in a measurement range, wherein the absolute signal representing said specific angle is generated near an initial position of the rotor;

means for sequentially generating increment signals at a predetermined interval in accordance with the rotation of the rotor in measurement ranges above and below the specific angle; and

means for adding or subtracting the increment signals to or from the absolute signal representing said specific angle to produce the absolute signal representing the rotation angle of the rotor, wherein a plurality of absolute signals are generated in the measurement range, each said absolute signal corresponding to a different section of the measurement range, whereby the interval of the absolute signal in a specific section of said measurement range is smaller than that in any other section of said measurement range.