JPH01134979A - Magnetosensor - Google Patents

Abstract

PURPOSE:To increase an effective magnetic flux which acts on a magnetic reluctance element so as to improve a magnetosensor in conversion efficiency by a method wherein a ferromagnetic thin film is formed on a space adjacent to two or more magnetic reluctance elements formed on an insulating substrate being insulated from other conductive sections. CONSTITUTION:Two or more magnetic reluctance elements 4-1 formed of a magnetic thin film are provided onto an insulating substrate 3-1 at the pitch of pi, and magnetic flux induction sections 5 are provided to an empty space between a terminal section 4-3 of the element 4-1 and a lead-out section 4-2 which servess both as connecting sections and lead-out terminals of two elements and the element 4-1 and the lead-out section 4-2, being insulated from other conductive sections. By these processes, a magnetic flux generated from a permanent magnet is induced to the magnetic induction section 5 and made to enable to the ratio of its portion which passes in parallel through the magnetic reluctance element 4-1 to itself to increase. As a result, the magnetosensor 3 can be improved in conversion efficiency.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Purpose of the Invention [Field of Industrial Application] The present invention relates to the structure of a magnetic sensor used in a magnetic encoder that detects the speed or position of a moving body.

[Prior Art] Fig. 3 is a diagram showing the concept of a conventional magnetic encoder, in which (a) shows the concept of the structure, (b) shows the correlation between the permanent magnet of the magnetic drum and the magnetic sensor, and ( C) each shows the concept of an electric circuit.

In the illustrated magnetic encoder, N and S magnetic poles of a permanent magnet 2 are alternately magnetized at equal intervals on the outer periphery of a magnetic drum fixed to a rotating shaft 1, and a magnetic resistance element 4 is connected to the permanent magnet 2 through an appropriate gap. A magnetic sensor 3 having a magnetic drum is disposed facing the magnetic sensor, and by detecting six resistance changes of a magnetoresistive element of the magnetic sensor, the speed or position of a rotating shaft to which a magnetic drum is fixed can be detected. The correlation between the permanent magnet of the magnetic drum and the magnetoresistive element of the magnetic sensor is as shown in figure (b), so that the arrangement pitch of the four magnetoresistive elements 4 is π with respect to the magnetic pole pitch of 2π of the permanent magnet 2. It is located in

Furthermore, as shown in the figure (c), four magnetoresistive elements 4 are connected to form a bridge, and a power source E is connected to the diagonal points c and d of the bridge, and the rotating shaft 1 is rotated at a and b. By doing so, the magnetic pole pitch of the permanent magnet 2.

It is configured to obtain a sinusoidal output voltage with twice the period, and by measuring this output voltage, the position or speed of the rotating shaft can be detected.

Figure 2 is a plan view (a) showing the arrangement of the magnetic resistance elements of the magnetic sensor conventionally implemented in the magnetic encoder shown in Figure 3, and the magnetic poles of the permanent magnet attached to the moving body (rotating shaft). FIG. 4 is a cross-sectional view (b) showing the correlation between the flow of magnetic flux between the magnetic sensor and the magnetoresistive element of the magnetic sensor.

(a) The magnetic sensor 3 shown in the figure has an insulating substrate 3-
A thin film of a magnetic material having a composition of nickel, cobalt, or an alloy thereof is formed on the surface of 1 to form a plurality of (4 in the illustrated example)
) A magnetic resistance element 4-1, one terminal 4-3 of each of the elements, and a conductor part 4-2 which also serves as a connecting point and an extraction terminal for the two elements, and The resistance elements 4-1 are arranged at a pitch of π.

(b) Figure is a cross-sectional view taken along the line A-A' in Figure (a) together with permanent magnets arranged opposite to each other. As shown by the broken line, part of the magnetic flux emitted from the permanent magnet 2 passes through the magnetoresistive element 4-1 in a substantially parallel manner, but most of it passes through the permanent magnet without passing through the magnetoresistive element. I am taking the route back to .

[Problems to be solved by the invention] In the magnetic sensor according to the prior art, as shown in figure (b), only a part of the magnetic flux emitted from the permanent magnet penetrates the inside of the magnetoresistive element, and the magnetic flux is detected. However, since most of the other flux does not pass through the magnetoresistive element, the detection efficiency of the magnetic flux is low.In order to increase the detection efficiency, the gap G between the permanent magnet and the magnetic sensor is shortened to reduce the magnetic resistance. Although measures have been taken to increase the effective magnetic flux penetrating the element, there is a problem in that the length of the air gap G cannot be shortened beyond a certain limit, and the conversion efficiency cannot be increased.

(2) Structure of the Invention [Means for Solving the Problems] In order to solve the problems in the prior art as described above, the present invention provides a magnetic sensor with a plurality of magnetoresistive elements formed on an insulating substrate constituting a magnetic sensor. The present invention provides a magnetic sensor having a structure in which a thin film of magnetic material is disposed in a space insulated from other conductive parts.

[Function] The magnetic sensor of the present invention has a thin film of magnetic material formed in a space adjacent to the magnetoresistive element and insulated from the magnetoresistive element and other conductive parts, so that the magnetic flux emitted from the permanent magnet flows through the insulation. The rate of parallel penetration through the magnetoresistive element is increased due to the magnetic thin film, which has the effect of increasing the conversion efficiency.

[Embodiment of the invention] FIG. 1 is a plan view (a) of a magnetic sensor showing an embodiment of the invention.
) and a cross-sectional view (b) showing the flow of magnetic flux between the magnetoresistive element and the permanent magnet.

(a) In the figure, a plurality of (four in the illustrated example) magnetoresistive elements 4-1 are arranged at a pitch of π using a thin film of magnetic material on the surface of an insulating substrate 3-1 made of glass or the like, and terminals of the elements are arranged. Part 4-
3 and 4-, which also serves as the connection part of the two elements and the terminal part of the extraction point.
2, it is characterized by a structure in which a magnetic flux guiding part 5 is provided in a space between the magnetoresistive element 4-1 and the lead-out part 4-2, insulated from other conductive parts.

As shown in the cross-sectional view of (b), the effect of the magnetic flux guiding section 5 is that the proportion of magnetic flux emitted from the permanent magnet being guided by the magnetic flux guiding section 5 and passing through the magnetoresistive element 4-1 in parallel increases. ,
This has the effect of increasing the conversion efficiency and increasing the output voltage of the magnetic sensor 3 when the length of the air gap G is the same, and in some experimental examples, an increase of about 10% was obtained.

Moreover, the magnetic flux guide part 5 is a thin film of the same magnetic material as the magnetoresistive element,
Since it is formed at the same time as forming the magnetoresistive element, no new material parts are required.

[Effects of the Invention] Since the present invention has the above-described configuration, the magnetic flux guiding part is insulated from other conductive parts by a thin film of magnetic material in the space adjacent to the plurality of magnetoresistive elements and the lead-out part of the magnetic sensor. This arrangement increases the effective magnetic flux acting on the magnetoresistive element and increases the conversion efficiency of the magnetic sensor, which has the effect of increasing the length of the gap between the permanent magnet and the magnetic sensor.

[Brief explanation of the drawing]

FIG. 1 is a plan view (a) of a magnetic sensor according to the present invention and a cross-sectional view (b) showing the flow of magnetic flux between a permanent magnet and the magnetic sensor.
) and FIG. 2 is a plan view of a magnetic sensor according to the prior art (a
), a cross-sectional view (b) showing the flow of magnetic flux between the permanent magnet and the magnetic sensor, and FIG. They are a diagram (b) showing the correlation with the magnetoresistive element of the sensor and an electric circuit diagram (c). Explanation of symbols 1... Rotating shaft, 2... Permanent magnet of magnetic drum, 3...
...Magnetic sensor, 3-1...Insulating substrate, 4.4-1.
... Magnetoresistive element, 4-2... Connection part, 4-3...
Terminal section. 5... Magnetic flux guiding part, R□R, R, R,... Resistance of magnetic resistance element, E... Power source. Patent applicant Nippon Servo Co., Ltd.

Claims (1)

[Claims] In a magnetic sensor having a plurality of ferromagnetic thin film magnetoresistive elements formed on an insulating substrate, a ferromagnetic thin film is placed in a space adjacent to the plurality of ferromagnetic thin film magnetoresistive elements on the insulating substrate. A magnetic sensor characterized by being formed insulated from a portion of the magnetic sensor.