JPH02232518A - Magnetic sensor - Google Patents

Abstract

PURPOSE:To make it possible to improve the detecting accuracy (interpolating accuracy) of a magnetic sensor by forming the output voltage from the magnetic sensor in a triangular waveform. CONSTITUTION:Magnetizing parts 2 are continuously arranged in the moving direction of a scale on a main body 1a of a magnetic scale with the interval of the same length of the magnetizing part 2 being provided. The magnetic field of the magnetizing part acts in the perpendicular direction with respect to the moving direction. Magnetizing parts 2' whose direction of the magnetic field is reverse with respect to the continuously arranged magnetizing parts 2 are arranged in parallel. The magnetizing parts 2 and 2' are arranged so that they are shifted by one length of the magnetizing part. A magnetoresistance effect element 2 which is arranged so as to face the magnetizing parts 2 and 2' is formed of a magnetic body pattern wherein two long side parts 4a and a plurality of short side parts 4b are continued at right angles. Both ends are connected to a power source 5. The central part of the long side parts 4a is made to be an output terminal 6. The directions of the magnetic fields of the magnetizing parts 2 and 2' are orthogonal to the moving direction of the scale 1. Therefore, the strength of each magnetic field on the scale 1 is changed in a pulse pattern. Therefore, the resistance of the long side parts 4a of the element 4 generates the resistance change in a triangular wave shape at the same phase. Therefore, the voltage change in the triangular shape is outputted from the output terminal between the long side parts 4a.

Description

Detailed Description of the Invention "Field of Industrial Application" The present invention relates to a magnetic sensor that can detect the speed, etc. of a linear scale or rotary scale magnetized by alternately changing the direction of the magnetic poles using a magnetoresistive element. Regarding sensors. "Prior Art" As shown in FIGS. 4 to 7, a conventional magnetic sensor has a magnetoresistive element 1) facing a magnetic drum 10 whose north and south poles are alternately magnetized. The magnetoresistive element ll detects the magnetic change caused by rotation, and the rotational speed or rotational position of the magnetic drum 10 can be detected. Magnetic material pattern l of EB magnetoresistance effect element l1
2 is arranged as indicated by the broken line in FIG. 4, and the magnetic material pattern l
The long side of the magnetic drum 2 is oriented perpendicular to the direction of rotation of the magnetic drum 10. Therefore, as shown in FIG. 5, both ends of the magnetic pattern l2 are connected to the power source l3, and when the magnetic drum 10 rotates, the magnetic field in the direction of the arrow l4 is applied to the two long sides of the magnetic pattern (resistors Rl, R -) crosses, a voltage change based on the resistance change is output to the central output terminal l5 of the magnetic material pattern l2. The equivalent circuit of the FB physical pattern l2 is shown in Figure 6. Also,
Magnetic field strength in the X direction (direction of movement of the magnetic drum) acting on the magnetic material pattern 12, resistances R1 and R2, and output voltage ■
The changes in were as shown in Figure 7. "Problems to be Solved by the Invention" In conventional magnetic sensors, the long sides of the magnetic material pattern are perpendicular to the direction of movement of the magnetic scale, so the resistance change R. R. ．． is a sine wave as shown in FIG. 7, and the output voltage VGi from the output terminal becomes a sine wave only in a small region of the magnetic field H as shown in FIG. 7, and the sine wave region is narrow. As a result, the detection accuracy (interpolation accuracy) of the magnetic sensor decreased, making it difficult to control the device based on the detected values. Therefore, an object of the present invention is to make the output voltage of a magnetic sensor have a triangular waveform, improve interpolation accuracy, and facilitate control of various devices. ``Means for Solving the Problems J'' The present invention provides a field sensor in which a magnetoresistive element is disposed opposite to a magnetic scale, in which a magnetic scale main body includes:
Magnetized parts on which a magnetic field acts perpendicularly to the direction of movement are arranged continuously in the direction of movement of the magnetic scale with the same spacing therebetween.
Furthermore, the @tabe where the magnetic field acts in the opposite direction to the @stone part is arranged parallel to the one celadon part by the same pitch, and the long side of the magnetic material pattern of the magnetoresistive element is the movement of the magnetic scale. This is a magnetic sensor placed in the same direction as the direction. Note that in order to make the voltage output of the magnetic sensor more similar to a triangular wave, it is desirable that the long side of the magnetic material pattern be approximately the same length as one magnetized part of the magnetic scale. "Function" In the magnetic sensor of the above means, the distance between each magnetized part of the magnetic scale is the same as that length, and the two rows of magnetized tracks are shifted by one magnetized part, and each magnetized part is spaced apart by the same length. Since the direction of the magnetic field in the magnetic part is perpendicular to the moving direction of the magnetic scale, the magnetic field strength on the magnetic scale changes in a pulsed manner. Therefore, the resistance of the two long sides of the magnetic material pattern of the magnetoresistive element causes a triangular wave-like resistance change with the same phase. Voltage changes are output. "Example" An example of the magnetic sensor of the present invention will be described with reference to FIGS. 1 to 3. The magnetic scale may be a linear type or a rotor type, but in this example, a linear type magnetic scale will be used. In the magnetic scale l, magnetized parts 2, on which a magnetic field acts perpendicularly to the direction of movement of the magnetic scale main body 1a, are continuously arranged in the direction of movement of the magnetic scale, with an interval of the same length as the magnetized parts 2. In addition, in the magnetic scale l, a magnetized part 2'' whose magnetic field is opposite to the magnetized part 2 in the continuous arrangement described above is arranged parallel to the magnetized part 2, and the magnetized parts 2 and 2° each have one @magnetized part. They are placed offset by the length of the length. A magnetoresistive element 3 is placed opposite the two rows of magnetized parts 2 and 2 degrees of the magnetic scale. The i-resistance effect element 3 is 2
It is formed by two long side parts 4a and a plurality of short side body patterns 4, both ends of which are connected to a power source 5, and the central part between the two long side parts 4a is used as an output terminal 6. The equivalent circuit of the magnetoresistive effect element constructed in this way is shown in FIG. 3, and the resistance of each long side portion 4a is R. ．． R. It is shown as follows. In addition,
In this embodiment, each of the two long sides 4a is formed with four pieces, but the number is not limited to six or more. It is desirable that the length of the long side 4a of the magnetic material pattern 4 be approximately the same length as the length P of one magnetized portion 2 of the magnetic scale, since the output voltage V tends to become a triangular wave. Further, as described above, it is desirable that the length W of the short side portion 4b of the magnetic material pattern 4 is approximately the same as the width W of the magnetized portion 2 of the magnetic scale. Using the magnetic sensor configured as described above, the magnetic scale is moved to increase the strength of the magnetic field H, . H. , the resistances R, , R2 of each long side of the magnetic pattern 2, and the output voltage (■) from the output terminal 6 of the magnetic sensor were measured. As can be seen from FIG. 1(B), the magnetic field strengths at the magnetized portions 2 and 2 degrees of the magnetic scale l are approximately the same value, and the pulse waves are shifted by half a pitch, and the resistance R+. It can be seen that Rz is a triangular wave with the same phase, and the output voltage V is a triangular wave. "Effects of the Invention" The magnetic sensor of the present invention has the magnetized parts of the magnetic scale arranged consecutively at intervals of the same length, and the direction of the magnetic field is made perpendicular to the moving direction of the magnetic scale, and the magnetoresistive element Since the long side of the magnetic pattern is aligned in the same direction as the moving direction of the magnetic scale, the output voltage from the magnetic sensor becomes a continuous triangular wave, making it easier to improve interpolation accuracy. Control of the device based on the detected values becomes easier and accuracy can be improved.

[Brief explanation of the drawing]

FIG. 1(A) is an explanatory diagram of the magnetic sensor of the present invention, FIG. 1(B)
is a waveform diagram showing the detection waveform of the magnetic sensor, Figure 2 is an explanatory diagram of the magnetoresistive element, Figure 3 is a circuit diagram of the magnetoresistive element, Figure 4 is a perspective view of a conventional magnetic sensor, and Figure 5. is the fourth
FIG. 6 is a perspective view of the magnetoresistive element of the magnetic sensor shown in the figure, FIG. 6 is a circuit diagram of the magnetoresistive element of FIG. 5, and FIG. 7 is a waveform diagram of each detected value of the conventional magnetic sensor. l: Magnetic scale 2: Attachment part 4: Magnetoresistive element 4a; Long side part

Claims (2)

[Claims] (1) In a magnetic sensor in which a magnetoresistance effect element is arranged facing a magnetic scale, the magnetic scale is moved so that the magnetized part, on which a magnetic field acts perpendicularly to the direction of movement of the magnetic scale body, is spaced at the same distance as that of the magnetized part. The magnetic body of the magnetoresistive element is arranged continuously in the direction of the magnetoresistive element, and magnetized parts on which a magnetic field acts in the opposite direction to the magnetized part are shifted by the length of the one magnetized part and arranged in parallel at the same pitch. A magnetic sensor characterized in that the long side of the pattern is arranged in the same direction as the moving direction of the magnetic scale. (2) The magnetic sensor according to claim 1, wherein the long side of the magnetic material pattern is formed to have approximately the same length as one magnetized portion of the magnetic scale.