JPS6270702A - Magnetic length measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain the detection signal of a sine wave even by one magnetoresistance element and to make it possible to easily detect zero-cross, by magnetizing a magnetic linear scale by multiplexing signals and applying bias to the change of magnetic flux. CONSTITUTION:A magnetoresistance element 2 is provided in close vicinity to a magnetic linear scale 1 and the magnetic flux generated from the scale 1 is detected by said element 2. The scale 1 is magnetized by superposing sine wave signals A, B and further adding bias D. This magnetization is performed by moving the scale 1 while signals are made to flow to a recording head and the cycle of the signal B is set to odd number times that of the signal. Relative positional change is applied between the magnetic scale 1 and the element 2 and magnetic flux is detected by a voltage dividing circuit consisting of the element 2 and a resistor 3 to obtain signals A1, B1. The signals A1, B1 are amplified by an amplifier 4 and subsequently separated into individual frequency components by BPF5, 6.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Industrial Application Field The present invention relates to a magnetic length measuring device that measures distance using a combination of a magnetic linear scale and a magnetic sensor.

(2) Conventional technology A magnetic linear scale magnetized at regular intervals is combined with a magnetic sensor such as a magnetoresistive element, and changes in magnetic flux detected by moving one from a reference point to a measurement point are pulsed. It is known to measure distance by counting. Magnetic linear scale has north and south poles
Generally, magnets are magnetized so that the poles are arranged alternately at regular intervals.

(3) Problems to be solved by the invention Since the magnetic length measuring device from FFE detects only the number of changes in magnetic flux, it detects only the number of changes in magnetic flux. The problem was that it could not be detected.

(4) Means for solving the problem and rt = use - The present invention was made in view of the above points, and aims at more advanced distance measurement such as detection of a specific point. In order to achieve this, the magnetic linear scale is magnetized by multiplexing signals to multiple types of signals, thereby detecting multiple types of magnetic flux changes, and is configured to detect multiple types of magnetic flux changes by applying a bias to the magnetic flux changes. .

(5) Examples Hereinafter, the present invention will be explained based on the drawings.

1 to 3 are schematic diagrams, characteristic diagrams, and circuit diagrams showing a first embodiment of a magnetic length measuring device according to the present invention. In FIG. 1, a magnetoresistive element 2 is placed close to a magnetic linear scale 1.
is provided, and the magnetic flux generated from the magnetic linear scale 1 is detected by the magnetoresistive element 2. The magnetoresistive element 2 has the magnetic field/resistance change rate characteristics shown in FIG.

The magnetic linear scale 1 is magnetized by superimposing two sine wave signals A and B whose waveforms are shown in the lower part of FIG. 2 and further applying a bias D. Magnetization is performed by moving the magnetic linear scale 1 while sending a signal in which signals A, B and bias D are superimposed to the recording head, similar to the relationship between the magnetic tape and the recording head in a tape recorder. The period of signal B is selected to be an odd multiple of the period of signal A, and in the example shown in FIG. 2, signal B has a period three times that of signal A.

Such a magnetic scale 1 is arranged as shown in FIG. 1, and the relative positional change between the magnetoresistive element 2 and the magnetoresistive element 2 is 17-, and the separation between the magnetoresistive element 2 and the resistor 3 as shown in FIG. By detecting the magnetic flux in the pressure circuit, the signal A1 shown in the upper right of Figure 2 is generated.
and B1 are obtained.

Signals A1 and B1 are amplified by amplifier 4 and then separated into individual frequency components by bandpass filter 5.6.

FIG. 4 is a schematic diagram showing the second embodiment. Components in the drawings that are the same as those in FIGS. 1 to 3 are designated by the same reference numerals and their explanations will be omitted.

In this embodiment, the magnetic linear scale 1 has a sine wave signal A,
B and is magnetized without applying bias D. Instead, a magnet 7 is attached near the magnetoresistive element 2. The magnetic resistance element 2 detects the magnetic flux from the magnet 7 and the magnetic flux from the magnetic linear scale 1 by superimposing them. As a result, the detection signals A1 and B1 shown in the upper right corner of FIG. 2 are obtained as in the previous embodiment. As for the detection circuit, the circuit shown in FIG. 2 can be used as is.

(6) Effects of the Invention As explained above, the present invention detects multiple types of magnetic flux changes by multiplexing multiple types of recording signals and magnetizing the magnetic linear scale. More advanced distance measurements such as detection can be performed. Also, since we added a bias to the magnetic flux change and detected it,
A sinusoidal detection signal can be obtained even with - magnetoresistive elements, and zero-cross detection can be easily performed.

[Brief explanation of drawings]

1 to 3 show a first embodiment of a magnetic length measuring device according to the present invention, in which FIG. 1 is a schematic diagram, FIG. 2 is a characteristic diagram, and FIG.
The figure is a circuit diagram. FIG. 4 is a schematic diagram showing a second embodiment of the magnetic length measuring device according to the present invention. 1. Magnetic linear scale 2. Magnetoresistive element

Claims (1)

[Claims] In a magnetic length measuring device that has a magnetic linear scale and a magnetic sensor that detects the magnetic flux of the magnetic linear scale, and measures length by changing the relative position of the magnetic linear scale and the magnetic sensor, multiple types of recording signals are multiplexed. 1. A magnetic length measuring device, characterized in that a plurality of types of magnetic flux changes are detected by magnetizing the magnetic linear scale, and the magnetic flux changes are detected by applying a bias.