Absolute encoder and absolute value signal generation method

• US 20050122242A1
• Filed: 10/24/2002
• Published: 06/09/2005
• Est. Priority Date: 12/21/2001
• Status: Active Grant

• Current Assignee: Kabushiki Kaisha Yaskawa Denki
• Original Assignee: Kabushiki Kaisha Yaskawa Denki
• Inventors: Arinaga, Yuji, Suzuki, Koji, Inenaga, Masamichi
• Granted Patent: US 7,266,567 B2
• Time in Patent Office: Days
• US Class Current: 341/111
• CPC Class Codes: G01D 5/2452 incorporating two or more tracks having an (n, n+1, ...) relationship
• CPC Class Codes: Y10S 707/99942 Manipulating data structure, e.g. compression, compaction, compilation
• CPC Class Codes: Y10S 707/99945 Object-oriented database structure processing
• CPC Class Codes: Y10S 707/99948 Application of database or data structure, e.g. distributed, multimedia, or image

Abstract

ABSTRACT An absolute encoder is arranged by a first memory 23 for storing thereinto an absolute value signal which is produced by an absolute value signal producing section 6 every constant time period; a second memory 24 for storing thereinto an absolute value signal which has been produced in one-preceding time period with respect to a time period of an absolute value signal entered into the first memory 23; a comparing/calculating section 25 for comparing the absolute value signal stored in the first memory 23 with the absolute value signal which has been produced in the one-preceding time period and has been stored in the second memory 24 so as to calculate an increase/decrease amount; a dividing process section 26 for dividing the increase/decrease amount in an equal rate within a producing time period of the absolute value signal; and an interpolated absolute value signal producing section 27 for reading the absolute value signal which has been produced in the one-preceding time period, and thereafter, for adding/subtracting the divided increase/decrease amount in a stepwise manner with respect to the read absolute value signal. As a consequence, both the absolute encoder and an absolute value signal producing process method thereof can be provided, which can produce a continuous interpolated absolute value signal which does not depend upon an absolute value producing time period, a control time period of a motor control apparatus, and a transfer method.

Claims

1. An absolute encoder comprising:

a plurality of slit streams having different pitch numbers from each other, in which positional information of the same pitch is formed;

a plurality of sensors which are relatively moved with respect to said slit streams so as to detect said positional information;

a phase modulating section for converting a signal derived from said sensor into a phase signal;

a phase difference signal producing section for converting both said phase modulation signal and a phase difference signal between two pieces of arbitrary phase signals into a digital signal; and

an absolute value signal producing section for producing a signal which is related to an absolute value position in a constant time period based upon the digital signal converted by said phase difference signal producing section and the phase difference signal;

wherein;

the absolute encoder is arranged by;

a first memory for storing thereinto an absolute value signal which is produced by said absolute value signal producing section every constant time period;

a second memory for storing thereinto an absolute value signal which has been produced in one-preceding time period with respect to a time period of an absolute value signal entered into said first memory;

a comparing/calculating section for comparing the absolute value signal stored in said first memory with the absolute value signal which has been produced in said one-preceding time period and has been stored in said second memory so as to calculate an increase/decrease amount;

a dividing process section for dividing said increase/decrease amount in an equal rate within a producing time period of said absolute value signal; and

an interpolated absolute value signal producing section for reading the absolute value signal which has been produced in said one-preceding time period, and thereafter, for adding/subtracting said divided increase/decrease amount in a stepwise manner with respect to the read absolute value signal.

2. In an absolute encoder in which:

positional information as to a plurality of slit streams having different pitch numbers from each other is detected by a plurality of sensors;

a signal derived from said sensor is converted into a phase signal by a phase modulating section;

both said phase modulation signal and a phase difference signal between two pieces of arbitrary phase signals are converted into a digital signal by a phase difference signal producing section; and

a signal related to an absolute value signal is produced in a constant time period based upon the digital signal converted by said phase difference signal producing section and the phase difference signal by an absolute value signal producing section,

an absolute value signal producing process method of the absolute encoder wherein;

an absolute value signal which is produced by said absolute value signal producing section every constant time period is stored into a first memory;

an absolute value signal which has been produced in one-preceding time period with respect to a time period of an absolute value signal entered into said first memory is stored into a second memory;

the absolute value signal stored in said first memory is compared with the absolute value signal which has been produced in said one-preceding time period and has been stored in said first memory by a comparing/calculating section so as to calculate an increase/decrease amount;

said increase/decrease amount is divided by a dividing process section in an equal rate within a producing time period of said absolute value signal; and

after reading the absolute value signal which has been produced in said one-preceding time period, said divided increase/decrease amount is added/subtracted in a stepwise manner with respect to the read absolute value signal by an interpolated absolute value signal producing section.