JP2005345375A - Electromagnetic induction type abs encoder - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce a period of time for calculating the absolute position in an electromagnetic induction type ABS encoder, equipped with a plurality of incremental scales having different wavelengths. <P>SOLUTION: In the electromagnetic induction type ABS encoder, equipped with the plurality of incremental scales 13A, 13B and 13C having different wavelengths, all the scales 13A, 13B and 13C are detected at its power-on timing, and the absolute position is obtained and preset to a counter 42. After the timing, only a part (13A) of the scales is detected, and incremental counting for the preset value in the counter are carried out. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an electromagnetic induction type ABS encoder having a plurality of incremental scales having different wavelengths, and more particularly to an electromagnetic induction type ABS encoder capable of quickly detecting an absolute position.

  As illustrated in FIG. 1, the main scale 12 and the index scale are caused by electromagnetic induction of an encoder pattern 10 including a plurality of coils 14 arranged in the longitudinal direction of the main scale 12 and a transmission coil 18 and a reception coil 19 arranged on the index scale 16. There are known electromagnetic induction encoders that detect 16 relative position changes (see Patent Documents 1 and 2). In the figure, 20 is a driving circuit, and 30 is a receiving circuit.

  In such an electromagnetic induction type encoder, as shown in FIG. 2, the coil 14 has a plurality of rows with different wavelengths, for example, a scale (referred to as a fine scale) 13A having fine tracks with the shortest wavelength, and a single wavelength. It is composed of a scale (coarse scale) 13C having the longest coarse track, and a scale (referred to as intermediate scale) 13B having an intermediate track having an intermediate wavelength, and is an absolute value (also referred to as ABS position) of displacement of the main scale 12 and the index scale 16. Inductive ABS encoders that are required to obtain the above are also being developed.

  In such an electromagnetic induction type ABS encoder, as shown in FIG. 3, after receiving the position data request signal, the positions of two or more incremental scales 13A, 13B, 13C having different wavelengths are detected every time, and the absolute position is detected. Was synthesized (also referred to as ABS synthesis).

JP 2000-180209 A JP 2002-213906 A JP-A-63-71611

  For this reason, it takes a very long time to calculate the absolute position, and the speed of signal processing cannot be increased.

  In addition, as similar to the present application, in the patent document 3, the applicant detects the absolute position using the absolute scale when the power is turned on in the length measuring device including the incremental scale and the absolute scale, and then calculates the measurement using the incremental scale. Although it has been proposed to increase or decrease the numerical value, an absolute scale for detecting the absolute position is required in addition to the normal incremental scale.

  The present invention has been made to solve the above-mentioned conventional problems, and it is an object of the present invention to reduce the time for calculating the absolute position in an electromagnetic induction ABS encoder having a plurality of incremental scales having different wavelengths. To do.

  In the electromagnetic induction type ABS encoder having a plurality of incremental scales having different wavelengths, all scales are detected when the power is turned on, and absolute positions are obtained and preset in a counter. Thereafter, only some scales are detected. And the above-mentioned problem is solved by performing incremental counting with respect to the preset value of the counter.

  In addition, the incremental counting is performed only with the lowest scale so as to speed up the signal processing.

  Further, the reliability of the measured value is improved by collating the incremental count value by the lowest scale and the absolute position obtained by the lowest scale and some other scale.

  Further, the reliability of the measured value is further improved by obtaining the absolute position by alternately using some other scales.

  According to the present invention, since the number of scales to be detected each time is reduced, it is possible to shorten the time for calculating the absolute position.

  In particular, when the incremental count value by the lowest scale and the absolute position obtained by the lowest scale and some other scale are collated, the reliability of the measurement value can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 4, the first embodiment of the present invention includes an encoder pattern 10 including three incremental scales such as a fine scale 13A, an intermediate scale 13B, and a coarse scale 13C as shown in FIG. A drive circuit 20 for driving the transmission coil 18 (see FIG. 1) of the index scale 16 by, for example, LCR resonance, and a reception circuit 30A for receiving reception signals from the fine scale 13A, intermediate scale 13B, and coarse scale 13C, respectively. , 30B, 30C, and outputs from the receiving circuits 30A, 30B, 30C, all scales are detected when the power is turned on, and absolute positions are obtained and preset in the counter 42. Only the scale 13 is detected, and the input to the preset value of the counter 42 is detected. It is obtained by an arithmetic circuit 40 for performing Rimentaru counting.

  According to the present embodiment, when the power is turned on, as shown in FIG. 5A, all scales 13A, 13B, and 13C are detected, for example, the lower ABS position is obtained from the data of the fine scale 13A, and the two upper scales are obtained. The upper ABS position is obtained from the data of 13B and 13C, and the absolute position is obtained by combining them.

  Then, the ABS position is preset in the counter 42, and thereafter, as shown in FIG. 5B, the position is detected only by the fine scale 13A. As shown in FIG. 6, the incremental count with respect to the preset value of the counter 42 is performed. To obtain the absolute position.

  Thus, the absolute position data output time can be reduced by setting the scale to be measured each time to only the fine scale 13A.

  In the position detection routine based on incremental counting shown in FIG. 6, there is no method for detection when an abnormality occurs in the counter value due to the influence of disturbance noise or the like, causing a problem in data reliability. Therefore, a second embodiment of the present invention that solves this problem will now be described in detail.

  In this embodiment, in the electromagnetic induction type ABS encoder similar to that of the first embodiment shown in FIG. 4, as shown in FIG. 7, in parallel with the incremental counting by the fine scale 13A, the fine scale 13A and other scales (for example, The absolute position is detected by the intermediate scale 13B or the coarse scale 13C), and these are compared with each other so that the positions are verified.

  In this way, by comparing the two count values, the incremental count value can be guaranteed, and the reliability of the output data can be improved.

  At this time, as shown in FIG. 8, the reliability can be further improved by obtaining the absolute position by alternately using the intermediate scale 13B and the coarse scale 13C. Note that the absolute position can be obtained only by a combination of one scale 13B or 13C and the fine scale 13A.

  In the embodiment, the absolute position detection using all the incremental scales is performed only when the power is turned on. However, the absolute position detection can be performed periodically at a low speed or when an error is detected.

  In the above embodiment, there are three types of scales: fine, intermediate, and coarse. However, the application target of the present invention is not limited to this, and two or four or more scales may be used.

A plan view showing the configuration of an example of an electromagnetic induction encoder Plan view showing an arrangement example of three incremental scales Explanatory drawing which shows the conventional position detection routine of an electromagnetic induction type ABS encoder The block diagram which shows the structure of 1st Embodiment of this invention. Explanatory drawing which shows the position detection routine of 1st Embodiment. Explanatory drawing which similarly shows the position detection routine at the time of incremental counting Explanatory drawing which shows the position detection routine at the time of the incremental count and ABS value collation in 2nd Embodiment of this invention. Explanatory drawing which similarly shows the position detection routine of another scale

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Encoder pattern 12 ... Main scale 13A ... Fine scale 13B ... Intermediate scale 13C ... Coarse scale 16 ... Index scale 20 ... Drive circuit 30A, 30B, 30C ... Reception circuit 40 ... Arithmetic circuit 42 ... Counter

Claims (4)

In an electromagnetic induction ABS encoder having a plurality of incremental scales having different wavelengths,
All scales are detected when the power is turned on, the absolute position is obtained and preset to the counter,
Thereafter, the electromagnetic induction type ABS encoder is characterized in that only a part of the scale is detected, and the incremental count with respect to the preset value of the counter is performed.   2. The electromagnetic induction type ABS encoder according to claim 1, wherein the incremental counting is performed only with the lowest scale.   3. The electromagnetic induction ABS encoder according to claim 2, wherein the incremental count value obtained by the lowest scale is collated with the absolute position obtained by the lowest scale and some other scale.   4. The electromagnetic induction ABS encoder according to claim 3, wherein the absolute position is obtained by alternately using another part of the scale.

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