JPH08304108A - Magnetic sensor - Google Patents

Abstract

PURPOSE: To prevent any thermal ill effect, and obtain a proper mid-point voltage by providing a ceramics substrate with a large thermal conductivity and forming a magnetic resistance effect element (MR element) thereon. CONSTITUTION: A ceramics substrate 9 with a large thermal conductivity is used instead of a glass substrate with a small thermal conductivity. A thin glass layer 10 is formed on the substrate 9 to smooth the surface thereof, and the sensor pattern of MR elements is formed on the layer 10. Thus, since a heat generated due to self-heating of elements 6 themselves is transmitted to the layer 10 and is radiated well through the substrate 9, a magnetic sensor, whose mid-point voltage fluctuation is reduced, can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic sensor, and more particularly to a magnetoresistive effect element (hereinafter referred to as MR element) provided on the surface thereof.
The present invention relates to a magnetic sensor for a magnetic encoder, which converts the resistance change of (1) into an electric signal and detects the speed and position of a rotating body.

[0002]

2. Description of the Related Art FIG. 3 shows a magnetic encoder, 1 is a magnetic drum, 2 is magnetic information which is a signal of a constant recording wavelength recorded on the magnetic drum 1, 3 is a rotation axis, and 4 is the magnetic drum 1. The magnetic sensors are arranged to face each other with a certain gap.

4 and 5 show a conventional magnetic sensor 4 for a magnetic encoder, 5 is a non-magnetic insulating substrate such as a glass substrate, and 6 is a thickness 20 formed on the glass substrate 5.
An anisotropic MR element of a ferromagnetic thin film of NiFe, NiCo or the like of 0 to 500Å, 6'is a wide current path connected to the MR element 6, 7 is a protective film for protecting the MR element 6, and 8 is In the conventional magnetic sensor 4, which is a terminal portion, a full bridge two-phase output is obtained from the MR element 6.

[0004]

However, the above-mentioned MR
When the pattern pitch of the magnetically sensitive portion of the element sensor is very narrow, each adjacent MR element self-heats, but since the glass that is the substrate has a low thermal conductivity, there is little heat dissipation through the glass substrate. However, there is a drawback that the electric resistance changes due to the temperature rise, which causes the midpoint voltage fluctuation.

There is also a method of canceling the temperature change by providing a dummy heating resistor on the sensor pattern in order to prevent the temperature change, but this method is not sufficient.

The present invention eliminates the above drawbacks.

[0007]

The magnetic sensor of the present invention comprises:
It is composed of a ceramic substrate having a high thermal conductivity and a magnetoresistive effect element formed on the ceramic substrate.

Further, the magnetic sensor of the present invention comprises a ceramic substrate having a high thermal conductivity, a glass layer formed on the ceramic substrate, and a magnetoresistive effect element formed on the glass layer.

[0009]

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

In the magnetic sensor of the present invention, as shown in FIGS. 1 and 2, a ceramic substrate 9 having a high thermal conductivity is used instead of the glass substrate 5 having a low thermal conductivity.

In order to facilitate the formation of a magnetic film for the MR element 6, a thin glass layer 10 is generally formed on the ceramic substrate 9 for the purpose of smoothing the surface of the ceramic substrate 9 having irregularities. Then, the sensor pattern of the MR element 6 is formed thereon.

Since the magnetic sensor of the present invention has the above-described structure, even if the MR elements self-heat, the heat is transmitted through the thin glass layer 10 and is radiated well through the ceramic substrate 9. The magnetic sensor can be made to have the designed value with little fluctuation of the midpoint voltage.

In the above embodiment, the pattern arrangement for obtaining the two-phase output is described, but the same operation and effect can be obtained regardless of the pitch, the pattern arrangement and the number of output phases.

[0014]

As described above, according to the magnetic sensor of the present invention, there is a great advantage that a thermal adverse effect can be prevented and a good midpoint voltage can be obtained.

[Brief description of drawings]

FIG. 1 is a front view of a magnetic sensor of the present invention.

2 is an enlarged cross-sectional view of the magnetic sensor shown in FIG. 1 taken along the line BB.

FIG. 3 is a perspective view for explaining a magnetic encoder.

FIG. 4 is a front view of a conventional magnetic sensor.

5 is an enlarged cross-sectional view taken along the line AA of the magnetic sensor shown in FIG.

[Explanation of symbols]

 1 Magnetic Drum 2 Magnetic Information 3 Rotational Axis 4 Magnetic Sensor 5 Glass Substrate 6 Anisotropic MR Element 6'Current Path 7 Protective Film 8 Terminal Section 9 Ceramics Substrate 10 Glass Layer

Claims (2)

[Claims] 1. A ceramic substrate having high thermal conductivity,
A magnetic sensor comprising a magnetoresistive effect element formed on the ceramic substrate. 2. A ceramic substrate having high thermal conductivity,
A magnetic sensor comprising a glass layer formed on the ceramic substrate and a magnetoresistive effect element formed on the glass layer.