JPH0213244B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic scale that detects position information by detecting a leakage magnetic field of a magnetized body.

Conventional magnetic scales have a structure in which a plurality of permanent magnets (magnetized bodies) formed by cutting a magnetic material are arranged at predetermined locations, and a detection object is formed by cutting the magnetic material. There was one that was combined with an electromagnetic induction type bulk magnetic head that detects leakage magnetic fields. A conventional magnetic scale with this structure obtains a detection output (dφ/dt) according to a change in the relative position between the magnetized body and the magnetic head.

However, in the structure of the conventional magnetic scale described above, if the size of each magnetized body is relatively large, that is, if high measurement accuracy is not required, the size of each magnetized body is made small (for example, several dozen scales). It was not suitable for obtaining a highly accurate magnetic scale (on the order of μm).

The present invention has been made in order to eliminate the above-mentioned conventional drawbacks, and an object of the present invention is to provide a magnetic scale capable of making highly accurate judgments.

Hereinafter, the present invention will be explained in detail according to embodiments with reference to the drawings.

FIG. 1 is a perspective view of a magnetic scale showing one embodiment of the present invention.

Reference numeral 3 denotes a substrate, on which magnetized bodies 1 patterned by photolithography are arranged in parallel at equal intervals. The pattern forming technique using photolithography is used in the manufacturing process of semiconductor integrated circuits, and refers to a technique in which a pattern on a photomask substrate is transferred onto a substrate using light. Here, the pattern of the magnetized body 1 is formed using the technique used in manufacturing the semiconductor integrated circuit. According to the above pattern forming technique using photolithography, the magnetized body 1 can be formed into a shape on the order of several tens of micrometers, and the pattern position accuracy can be extremely high. Incidentally, if a strong external magnetic field is applied after forming the thin film pattern of the magnetic material and magnetization is performed all at once, a predetermined pattern of the magnetized material can be obtained with high accuracy.

An MR element (magnetoresistive effect element) 2 is arranged at a position facing the magnetized body 1, and detects the leakage magnetic field in the y direction generated from the magnetized body 1 by moving the MR element 2 in the x direction. Note that the magnetization direction of the magnetized body 1 is the x direction indicated by the arrow in the figure.

FIG. 2 shows the arrangement pattern of the magnetized bodies 1. A repeating pattern 4 is arranged in parallel with the repeating pattern of the magnetized body 1 shifted by one quarter from the end of the magnetized body 1.

The leakage magnetic fields in the y direction from the repeating pattern 4 of the magnetized body 1 have the same period shifted by one quarter, as shown in the magnetic field distribution curves 6 and 8 shown in FIG. 3, respectively. This magnetic field change is read by two MR elements, and the position from the reference is detected. There are two types of MR elements shown in FIG. Fig. 4A shows an MR element in which the detection signal 10 always changes only in the negative direction even if the external signal magnetic field 9 changes to positive or negative, and Fig. 4B shows the MR element 2 biased in advance even when the external signal magnetic field is zero. Since a magnetic field is applied, the external magnetic field 11
When changes to positive or negative, the detection signal also changes to positive or negative. Although the magnetic scale of this embodiment can be realized by using any of the MR elements having the characteristics shown in FIG. 4A and B, the MR element having the characteristics shown in FIG. element is valid.

FIG. 5 is a block circuit diagram showing one embodiment of a control circuit relating to the magnetic scale of the present invention.

MR elements 5-a, 5- from constant current power supply 5-1
A constant current is supplied to b and 5-c. MR element 5-
c has the role of temperature compensation with the leakage magnetic field detectors 5-a and 5-b, and the differential between the detectors 5-a and 5-b with respect to the MR element 5-c is generated by the amplifier circuit 5-3. It's amplified. The amplified signal from the amplifier circuit 5-3 is waveform-shaped by a waveform shaping circuit 5-4. Detector 5
Signals obtained by shaping the detection signals from -a and -b, respectively, are shown as magnetic field distribution curves 5 and 7 in FIG. Using the signals shown as the magnetic field distribution curves 5 and 7, a frequency dividing circuit 5-5 performs frequency division to improve accuracy. Further, the signals of the magnetic field distribution curves 5 and 7 are combined by a combination circuit 5-7 and inputted to an up-down counter 5-8 to display a read signal of the scale. Further, by arranging the magnetized bodies 1 and 4 at equal angles, it is possible to read out the angle in exactly the same way.

According to the present invention described in detail above, since the pattern of the magnetized body is formed finely on the order of several tens of μm by photolithography,
The detection position accuracy of the scale is extremely excellent. In addition, since a magnetoresistive element is used to detect the leakage magnetic field from the magnetized body, it is possible to sufficiently follow and detect the movement of the magnetized body in minute patterns (on the order of several tens of micrometers). . In addition, the magnetoresistive element described above does not generate a voltage for the first time due to a change in magnetic flux, unlike conventional general electromagnetic induction heads, and even if there is no change in magnetic flux (the magnetized body is in a stationary state), a magnetic Since it is a magnetic flux response type that can detect signals, it can sufficiently handle cases where there are small changes in magnetic flux, that is, when the relative speed between the magnetized object and the detector is very slow, improving the properties of the magnetic scale. It can greatly contribute to

[Brief explanation of drawings]

FIG. 1 is a perspective view showing the arrangement relationship between a patterned magnetized body and a signal detector according to the present invention. FIG. 2 is an arrangement diagram showing an example in which the ends of magnetized bodies patterned at equal intervals are shifted and arranged in two parallel rows. FIG. 3 is an explanatory diagram showing the magnetic field distribution in the y direction of the magnetized body shown in FIG. 2 and an example of a signal detected by a detector and then amplified and waveform-shaped. FIGS. 4A and 4B are characteristic diagrams showing the characteristics of the thin film magnetic effect element. FIG. 5 is a block circuit diagram showing an example of a control circuit for a magnetic scale according to the present invention. 1... Magnetized body, 2... MR element, 3... Substrate, 4... Arrangement pattern of magnetized body.

Claims (1)

[Claims] 1. A magnetized body formed into a microscopic pattern on the order of tens of micrometers by photolithography on a substrate, a detector that detects the leakage magnetic field from the magnetized body, and a control that performs signal processing on the output from the detector. a circuit section, the detector is configured with a magnetoresistive element made of a ferromagnetic thin film having uniaxial anisotropy, and the leakage magnetic field from the magnetized body is detected to detect a deviation from the reference value. A magnetic scale configured to measure position.