JPS5822913A - Position detecting scale - Google Patents

Abstract

PURPOSE:To obtain high output and high sensitivity characteristics, and to exactly prevent generation of an erroneous decision, by constituting a position detecting scale of a magnetic scale and a magnetic resistance detector, and obtaining the result of detection in a digital value. CONSTITUTION:When a magnetic resistance detector 3 of a position detecting scale moves along a magnetic medium 1, a signal S0 is obtained in the detector 3. In this case, to a magnetic resistance element 3a and 3b of the detector, a magnetic field is applied, by one polarization respectively, and amplitude of the signal S0 becomes 2 times of that of a signal obtained by only one element. Also, N groups of detectors 3 are arrayed at a position shifted by (n+1/2N) pitch at the array interval of a magnetized area 2 of the medium 1. In this way, from each detector 3, the signal S0 being distributed to a position shifted by the 1/2N pitch is obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a position detection scale, and particularly to an arrangement structure of a magnetic medium K - nine magnetized regions which are magnetized and written at short intervals and a magnetoresistive detector having a magnetoresistive effect.

BACKGROUND ART Conventionally, two types of systems have been proposed as position detection scales, for example, so-called linear scales that have a sense of equidistant volume: an electromagnetic induction system and an optical system. In the former electromagnetic induction method, a minute coil is placed in a straight line and an alternating current is passed through it, while a coil of the same shape is placed in the detector and placed on the straight line. When the detector moves near the coils, or when the coils are close to each other, an output voltage is excited in the detector coil by magnetic induction. In this case, since the voltage excited in the detector changes depending on the position of the coils that are close to each other, it is possible to electrically read dimensions that are smaller than the arrangement pitch of the coils arranged in a straight line. However, since all the signals obtained by the detector are analog signals, these signals cannot be applied as driving signals for robots or robots unless they are converted to N(, V) via an analog-to-digital converter. On the other hand, the optical method calculates this by counting the number of light pulses obtained through slits or light shielding films placed at regular intervals on a glass plate facing the light source. However, the performance of such optical linear scales is significantly affected by the environment in which they are used.In other words, when installed and used on a machine tool*, there is a risk of cutting oil scattering or The glass surface of the optical slit is contaminated by vapor deposition, reducing the amount of light transmitted and causing malfunctions.Furthermore, malfunctions caused by deterioration of the characteristics of the light emitting diode used as the light source are also ignored. I couldn't.

SUMMARY OF THE INVENTION Therefore, it is an object of the present invention to eliminate the above-mentioned drawbacks of the conventional scale, to provide a position detection scale that allows position detection results to be grasped using digital signals, and that does not exhibit any characteristic deterioration in the environment of use or pollution.

In order to achieve such an object, the present invention provides a magnetic scale in which magnetized regions are formed at regular intervals on a magnetic medium, and two magnetoresistive sensing elements having a magnetoresistive effect that extend the magnetized regions. A position detection scale is constructed with at least one set of magnetoresistive detectors.

Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a plan configuration diagram of main parts for explaining an example of a position detection scale according to the present invention. In the llil diagram,
Reference numeral 1 denotes a magnetic medium, and this magnetic medium 1 is formed by magnetizing magnetic poles at cape intervals, and nine magnetized regions 2 are provided to constitute a magnetic scale. Further, a magnetoresistive detector 3 having a magnetoresistive effect is placed close to the magnetic medium 1o11 scale, and the magnetoresistive detector 3 has two magnetoresistive elements 3m and 3b having a magnetoresistive effect, which are connected to the magnetic Magnetized on medium 1, 9 magnetized regions 20 intervals On (positive integer)
+x7 pitches apart and directly connected. Note that 3C is a common electrode, 3d, 3., 3
f is a signal output terminal.

In the position detection scale configured in this way, when the magnetoresistive detector 3 moves along the magnetic medium 1, since the magnetoresistive detector 3 has the equivalent circuit shown in FIG. The signal shown in the figure is obtained. In this case, since a magnetic field is applied to each of the magnetoresistive elements 3a and 3b of the magnetoresistive detector 3, the signal waveform 8 shown in FIG.
The amplitude Fi of o is twice that of the signal obtained with only one magnetoresistive sensing element.

Considering the case where multiple sets of magnetoresistive detectors 3 having such a basic configuration are arranged, the IN set of magnetoresistive detectors 3 are placed at positions that equally divide the arrangement interval of the magnetized regions 3 of the magnetic medium 10. Deploy. That is, N sets of magnetoresistive detectors 3 are arranged at positions shifted by (m+''/m) pitch from the arrangement interval of the magnetized regions 2.

In this case, n is a positive integer.

According to such a configuration, each of the N sets of magnetoresistive detectors 3 outputs signal waveforms s1°Bz, S8 .
g4pBm# obtained tL, 3rd EK indication L*(11) waveform s
K) One waveform is obtained with a distribution of 9 positions K) shifted by O trout ""/2N pitch. Here, if five sets of magnetoresistive detectors 3 are arranged, KFiN=5, "/2N-1/1・
becomes. That is, when five sets of magnetoresistive detectors 3 are used, the magnetic medium 1 is magnetized and the V!・Can read up to the dimensions.

#! FIG. 5 is a diagram illustrating a method for further finely reading out the finely read portion of the signal waveform shown in FIG. 4. In the figure, signal waveforms 9r, S! from two sets of the magnetoresistive detectors 3 (not shown) are shown. When there is, K, which determines the position below the resolution of AX that exists between signal waveforms S1 and Bz, can be calculated by simple calculation by reading the peak values of signal waveforms S1 and 82 at point X. . That is, as shown in the figure, the signal waveforms gx, g2! Let the intersection points on the axes be points AA and B, respectively, and let the desired point be point X. Further, the intersections on the vertical lines from points B, a, and X of the signal waveform S1 are respectively set as 0 point and point D, and the intersections on a straight line from the point X of the signal waveform S are set as 9 points. In this case, assuming that the distance range from AA to each point X, B, C, and D is linear for the signal waveform 5ttst, then the following approximately holds true, so the position of the X point to be found, that is, A
X is DX AX = Ail Waveform S
The peak values of 1 and 82 can be found by calculation. However, according to this method, the signal waveforms S1 and 8! at two points with different timings, 1 point and 1 point!
It is necessary to measure.

On the other hand, in order to facilitate measurement, approximate KC
B=D] C, 6 To1 (21 type Kara ID
X AX#-・□----@(31 2M DI Tona-sho, one point can be easily determined by measuring the peak values of signal waveforms s1 and 82 at the same time.

This measurement result is KA/D as commonly known.
By using a converter and a microcomputer together, calculations can be processed instantaneously.

For example, if N = 5 sets of magnetoresistive detectors 3 are used, and K is measured with an accuracy of 1/2N of the spacing of the magnetized regions 20,
If the measurement accuracy is improved by one order of magnitude and a method for finding the midpoint between two signal waveforms is also used, the initial O magnetization interval can be easily improved to 101 degrees. For example, when the magnetic regions 2 are magnetized on the magnetic medium 1 at intervals of about 0D5, it is possible to easily obtain a measurement accuracy of about o, oos.

In addition, in the above embodiment, a linear scale having an interval scale was used, but the present invention is not limited to this. Even when applied to a rotary encoder and a speed rotary encoder, the same effects as described above can be obtained.

As explained above, according to the present invention VI4, position detection results can be obtained with digital signals, and high output and high sensitivity IIL% can be obtained with no characteristic deterioration due to the usage environment, pollution, etc. 19. By using multiple magnetoresistive detectors, measurement accuracy can be improved, and by analyzing two signals, it is possible to reliably prevent false judgments. Excellent effects such as being able to read position information with high accuracy can be obtained.

[Brief explanation of drawings]

Figure 1 is a configuration diagram of the main parts explaining an example of the position detection scale according to the present invention 1, No. 211 is the equal piece aSIII of the magnetoresistive detector shown in Figure 1, and 3rd WA is the 9 magnetoresistive detector shown in Figure 2. The waveform diagram of the signal obtained by the detector, Figure 4, shows the output signal wave el1%Ia when using multiple sets of magnetoresistive detectors.
The s diagram is a diagram showing how to find an accurate position from two output signal waveform diagrams. 1... Magnetic medium, 2... Magnetized area, 3...
Magnetoresistive detector, Sm, 3b... Magnetoresistive element, 3
c...Common electrode, 8d, 3..., $f...Signal range) output terminal. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] (1) At least a magnetic scale comprising nine magnetized regions formed by magnetizing magnetic poles at regular intervals on a magnetic medium, and two magnetoresistive detection elements having a magnetoresistive effect for reading the magnetized regions of the magnetic scale. a set of magnetoresistive detectors, and the magnetoresistive detector is arranged such that the two magnetoresistive detection elements are arranged at positions n (positive integer) + 171 pitches of the distance between the magnetized regions of the magnetic scale. A 4+11 position detection scale configured by arranging and connecting in series. (21) When N sets of the W&magnetic resistance detectors are provided, each of the N sets is arranged at a position shifted by n (positive integer) + 1/!N pitches. 1
Position detection scale described in section.