JP2698650B2 - Magnetic encoder - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a magnetic encoder for detecting the position and speed of an object, and includes a ferromagnetic magnetoresistive element and a magnetic recording medium. Magnetic encoder.

[Prior Art] Conventionally, a magnetic encoder includes a ferromagnetic magnetoresistive element (hereinafter, referred to as an “MR element”) and a magnetic recording medium. Output type. This pulse output type generally has a built-in circuit for shaping the sine wave output signal of the MR element into a pulse wave. The output signal of the MR element has a temperature characteristic. If the amplitude of the output signal changes due to a temperature change, the duty of the pulse changes, and a position / speed detection error occurs. Also, in a sine wave output type magnetic encoder, MR
Since the output signal of the element is amplified as it is, a position / velocity detection error also occurs.

As described in Japanese Patent Application Laid-Open No. 60-192214, a conventional magnetic encoder has a stable output with respect to temperature by changing the amplification factor of an amplifier with respect to temperature in order to solve the above problem. Have gained. According to FIGS. 4 and 5 of the publication, the waveform shaping and shaping circuit performs an operation of increasing the amplification factor as the temperature rises. The waveform shaping circuit of FIG. 3 of the publication, in order to perform this operation, as heat-sensitive elements connected in parallel to the resistor R _1, a negative resistance to temperature - by adopting a thermistor having a temperature characteristic Has been realized.

Japanese Patent Application Laid-Open No. 54-115257 discloses an angle detector composed of an MR element and a magnetic recording medium, but does not take into account the occurrence of a position / speed detection error due to a temperature change.

[Problems to be Solved by the Invention] The above prior arts are (1) limited to a thermosensitive element having a negative temperature characteristic, and (2) the position of the thermosensitive element is not indicated, and No consideration is given to accurate temperature detection. (3) A thermistor can be considered as a known thermosensitive element having a negative characteristic with respect to temperature. However, the resistance and temperature characteristics of the thermistor are not linear but logarithmic. Changes to
That the temperature compensation accuracy of the encoder output signal is poor, and that the temperature characteristics of the thermistor can be used only in an approximately linear range in order to increase the temperature compensation accuracy, and that the encoder output signal compensation temperature range becomes narrower; 4) There was a problem that the selection of the temperature coefficient of the thermal element was not considered.

An object of the present invention is to provide a magnetic encoder capable of detecting position and speed with high accuracy even when used in an environment having a temperature change.

Another object of the present invention is to provide a magnetic encoder capable of easily and accurately positioning an MR element vapor-deposited substrate and its supporting structure during bonding and bonding.

Means for Solving the Problems In order to achieve the above object, a magnetoresistive element deposited substrate and its supporting structure are arranged so that the temperature coefficient of the magnetoresistive element is linearized. And a support structure, formed of a material capable of suppressing thermal stress generated at the joint, and the magnetoresistive element vapor-deposited substrate and the support structure are formed of a soft material capable of absorbing the thermal stress of the joint between each other. When the temperature characteristic of the output voltage of the magnetoresistive effect element is α, the temperature coefficient of the linear temperature sensor provided near the speed detection unit is β, and the temperature change amount is ΔT, (1+
ΔT · α / 100) (1 + ΔT · β / 100) ≒ 1. The temperature compensation is performed by a linear temperature sensor having a temperature coefficient β selected to satisfy the condition of 1 and an amplifier circuit. .

In addition, the position of the magnetoresistive element and the magnetic recording medium
The linear temperature sensor is provided at a position where the temperature becomes the same as that near the speed detection.

Furthermore, a groove for inflow of an adhesive is provided on a contact surface of the support structure of the magnetoresistive element deposited substrate with the magnetoresistive element deposited substrate.

[Operation] As described above, in the present invention, the magnetoresistive element-deposited substrate and the supporting structure thereof are connected to each other so that the temperature coefficient of the magnetoresistive element is linearized. It is formed of a material that can suppress the thermal stress generated at the joint. Thus, it is possible to prevent the output signal of the MR element from being non-linear due to the magnetostrictive characteristic caused by the thermal stress applied to the MR element, and to maintain the linearity of the resistance change rate characteristic of the MR element. As a result, even when used in an environment having a temperature change, it is possible to perform highly accurate temperature compensation of the output signal of the MR element.

Moreover, since the magnetoresistive element deposited substrate and its supporting structure are bonded by a soft adhesive capable of absorbing the thermal stress of the joint between the substrate and the MR element deposited substrate, the MR element deposited substrate and its supporting structure are thereby bonded. Since the thermal stress generated between the structures can be absorbed and the magnetostriction of the MR element caused by the thermal stress of both members can be prevented, the linearity of the temperature change characteristic of the resistance change rate of the MR element can be maintained well.

In the present invention, the temperature coefficient of the output voltage of the MR element is β,
When the amount of temperature change is ΔT, the linear temperature sensor
(1 + ΔT · α / 100) (1 + ΔT · β / 100) A temperature coefficient β selected so as to satisfy the condition of ≒ 1 is used. Thereby, the output voltage of the magnetic encoder can be stabilized with respect to temperature.

Further, in the present invention, a temperature near the position / speed detecting section of the MR element and the magnetic recording medium is detected by a linear temperature sensor having a temperature coefficient β selected so as to satisfy the above condition, and the detected temperature is amplified by an amplifier circuit. Then, by performing the temperature compensation, a sine-wave output having a small amplitude change of the output signal or a pulse output having a small duty change can be obtained. As a result, highly accurate position / velocity detection becomes possible.

In combination with the above operations, the position and speed of the object can be detected with high accuracy even in an environment having a temperature change.

In general, bonding and bonding between the MR element deposition substrate and its supporting structure are performed by pressing the side surface of the MR element deposition substrate against a highly-accurate alignment surface of the supporting structure and positioning the MR element on the supporting structure. This is performed by bonding with an adhesive applied to the contact surface of the element deposition substrate.

Therefore, in the present invention, a groove for injecting an adhesive is provided on the contact surface of the support structure with the MR element deposition substrate. By providing this groove, excess adhesive flows into the groove, making it possible to position the MR element deposition substrate and its supporting structure easily and with high accuracy, and to detect the position and speed of the object. Can be increased.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

1 to 17 show an embodiment of the present invention. FIG. 1 is a longitudinal side view of the entire magnetic encoder, and FIG.
FIG. 3 is a front view as viewed from the line II-II, and FIG.
FIG. 4 is a cross-sectional view taken along the line III, FIG. 4 and FIG. 5 are temperature diagrams of the MR ratio of the MR element, FIG. 6 is a junction model diagram of the MR element deposition substrate and its supporting structure, and FIG. FIG. 8 is a diagram showing the relationship between the relative output voltage of the magnetic encoder and the amount of change in temperature, FIG. 9 is an enlarged plan view of the MR element deposition substrate, FIG.
FIG. 9 is a side view of FIG. 9, FIG. 11 is a plan view of a support structure of the MR element deposition substrate, FIG. 12 is a view from the XII-XII line side of FIG. 11, and FIG. FIG. 14 is an enlarged plan view showing a coupled state of the MR element and its supporting structure, and FIG.
FIG. 16 is a side view of the figure, FIG. 16 is a view of an end bracket, which is a support structure for the magnetic recording medium, as viewed from the side where the magnetic recording medium is mounted, and FIG. 17 is a sectional view taken along line XVII-XVII of FIG. FIGS. 18 and 19 are temperature diagrams showing the resistance change rate of the MR element when the MR element and its supporting structure are formed of materials having different linear expansion coefficients.

In the magnetic encoder of the embodiment shown in FIGS. 1 to 17, as shown in FIG. 1, the end bracket 1, the case 2, the signal connector 4, the shaft 6, the magnetic recording medium 12, the magnet 13, a rotating shield plate 14 and a fixed shield plate 15, an MR element deposition substrate 18, a support structure 16 thereof, an amplification circuit printed board 24, and a linear temperature sensor.
27 and a semiconductor magnetoresistive element 28, and further has a temperature compensation circuit shown in FIG.

As shown in FIG. 1, the case 2 is attached to the end bracket 1 via an O-ring 3 and covers various members attached to the end bracket 1 and the like.

As shown in FIG. 1, the signal connector 4 is attached to the case 2 via an O-ring 5 so that a position / speed detection signal of the magnetic recording medium 12 is taken out from the signal connector 4 to the outside. Has become.

As shown in FIG. 1, the shaft 6 is rotatably supported on the end bracket 1 via a bearing 7, and is connected to an AC servomotor (not shown). As shown in FIGS. 1 and 2, the bearing 7 is attached to the end bracket 1 with a thrust ring 8 and a nut 9 and a bearing retainer 10 and a screw 11 so as not to escape.

The magnetic recording medium 12 is formed in a drum type as shown in FIG. On the outer peripheral surface of the magnetic recording medium 12, a large number of N and S poles are recorded at equal intervals. As shown in FIG. 1, the magnetic recording medium 12 is mounted on the shaft 6 so as to be able to rotate integrally therewith.

As shown in FIG. 1, the magnet 13 is attached to the magnetic recording medium 12 with a rotary shield plate 14 interposed therebetween.

The rotating shield plate 14 is attached to the magnetic recording medium 12 as shown in FIG.
Are fixed to the end bracket 1 as shown in FIG. The rotating shield plate 14 and the fixed shield plate 15 prevent the magnetic field of the magneto 13 from leaking and prevent the MR element group 19 from malfunctioning due to the leaked magnetic field.

The support structure 16 of the MR element vapor deposition substrate 18 is positioned with high accuracy on the end bracket 1 and is fixed to the end bracket 1 by screws 17 as shown in FIGS. Support structure 16 and end bracket 1
Will be described in detail later. This support structure 16
As shown in FIG. 1, a predetermined spacing (gap) S is provided between the magnetic recording medium 12 and the outer peripheral surface thereof, and
The element deposition substrate 18 is bonded by bonding. The shape and bonding of the contact surface between the support structure 16 and the MR element deposition substrate 18 will be described later in detail.

As shown in FIGS. 9 and 14, an MR element group 19 for detecting the position and speed of the magnetic recording medium 12 is deposited on the MR element deposition substrate. This MR element group 19 is composed of two MR elements 20, 21 as shown in FIG. Further, as shown in FIGS. 1, 9, and 14, a cable 22 for extracting a position / speed detection signal is connected to the MR element deposition substrate 18. The cable 22 is connected to a connector 23.

The amplifying circuit printed board 24 is, as shown in FIG.
Fixed shield plate 15 and spacer on end bracket 1
It is fixed by screws 26 with 25 interposed. The amplifier circuit printed board 24 includes an amplifier circuit (not shown), a magnet 13, and a cable connected to the MR element evaporation substrate 18.
A connector 23, a linear temperature sensor 27, and a semiconductor magnetoresistive element 28 are provided.

The amplifier circuit has an amplifier 31 shown in FIG. 7, and outputs a position / speed detection signal of the magnetic recording medium 12 detected by the MR element group 19 and converted into a voltage signal by the resistor 29 shown in FIG. It is designed to amplify.

The magnet 13 and the semiconductor magnetoresistive element 28 detect the position of the magnetic pole of the rotor of the AC servomotor. Based on this position information, the AC servomotor Is to be rotated.

The linear temperature sensor 27 is disposed near the position / speed detecting section of the MR elements 20 and 21 and the magnetic recording medium 12, and is attached to the amplifier circuit printed board 24 as shown in FIG. The linear temperature sensor 27 and the amplification circuit printed board 24
The temperature compensation is performed by the amplifier circuit provided in the first stage.

The temperature compensating circuit, as shown in FIG.
A resistor 29 connected to 0,21, another resistor 30, an amplifier 31 connecting these resistors 29,30, and an amplifier 3
1 and a linear temperature sensor 27 connected in parallel. In this temperature compensation circuit, when the magnetic fluxes φ ₁ and φ ₂ of the signal magnetic field are applied to the MR elements 20 and 21 as the magnetic recording medium 12 rotates, the electric resistance changes, and the voltage signal becomes e _i . The amplifier 31 is used to amplify the voltage signal e ₀ by the resistance ratio between the resistor 29 and the linear temperature sensor 27 to detect the position and speed of the magnetic recording medium 12.

By the way, the MR element deposition substrate 18 and its supporting structure 16
As a material of the material, a combination of materials having a large difference in linear expansion coefficient, for example, a material of the MR element deposition substrate 18, a borosilicate glass (linear expansion coefficient = 4.5 × 10 ⁻⁶ / deg), a material of the support structure 16, When aluminum (linear expansion coefficient = 24 × 10 ⁻⁶ / deg) is selected, as shown in FIGS. 18 and 19, the MR element has a non-linear resistance change rate temperature characteristic. This is because the MR element was distorted by the thermal stress applied to the MR element deposition substrate 18. Therefore, the material of the support structure 16 of the MR element deposition substrate 18 is austenitic stainless steel (linear expansion coefficient = 16 ×
When it is changed to 10 ⁻⁶ / deg), as shown in FIGS. 4 and 5, the temperature characteristic of the resistance change rate of the MR element becomes linear. This is because the thermal stress that can maintain the linear temperature characteristic of the resistance change rate is suppressed.

Incidentally, the configuration shown in FIG. 6 will be considered as a model of the MR element deposition substrate and its supporting structure. This sixth
In the model shown in the figure, the model 33 of the MR element deposition substrate (cross-sectional area ^{= 8.4 × 10 -3 mm 2)} , borosilicate glass (Young's modulus =
7000 kg / mm ² ), model 34 of supporting structure (cross section = 84 × 10
^-3 mm ² ) and aluminum (Young's modulus = 7200 kg / mm ² ), the bonding surface 35 of both models 33 and 34 is completely bonded with an adhesive and fixed. Thermal stress occurs at a temperature change of 5.0 kg / mm ² . If austenitic stainless steel (Young's modulus = 20400 kg / mm ² ) is selected as the support structure model 34, a thermal stress of 3.1 kg / mm ^{2 is} generated.

Therefore, in the present invention, the MR element deposition substrate 18 and the supporting structure 16 are made of a material capable of suppressing a thermal stress generated at a joint between the two members. In other words, for example, an MR element deposition substrate
When borosilicate glass is used as the material 18, austenitic stainless steel is used as the material of the support structure 16.

In FIGS. 18 and 19, when the ambient temperature is high, the resistance change rate temperature characteristic shows linearity because the adhesive used for bonding the MR element deposition substrate 18 and its support structure 16 softens, This is because thermal stress was absorbed.

Therefore, in the present invention, the joint between the MR element deposition substrate 18 and the supporting structure 16 is adhered with an adhesive capable of absorbing thermal stress, for example, a soft adhesive such as a silicon-based adhesive.

Further, in FIGS. 18 and 19, when the magnetic field is strong, the linearity with respect to the thermal stress is exhibited because, in the case of a strong magnetic field, the MR elements 20 and 21 are magnetically saturated. This is because the spin direction of the magnetic domain cannot be changed by external stress. On the other hand, in the case of a weak magnetic field, when stress is applied to the MR elements 20 and 21, the spin direction changes to match the magnetostriction due to the change in the spin direction of the magnetic domain and the elongation due to the stress. Becomes nonlinear.

As described above, by maintaining the linearity of the resistance change rate temperature characteristics of the MR elements 20 and 21, it is possible to perform highly accurate temperature compensation of the output signals of the MR elements 20 and 21.

In FIG. 7, the output voltage e _i of the MR elements 20 and 21 has a temperature characteristic due to the temperature characteristics of the resistance change rate of the MR elements 20 and 21 and the signal magnetic field temperature characteristic of the magnetic recording medium 12. The temperature coefficient is α (% / ° C.), the temperature change is ΔT (° C.), Δ
Assuming that the output voltage e _i of the MR elements 20 and 21 at T = 0 is e ′ _i , the output voltage is expressed as follows: e _i = e ′ _i (1 + ΔT · α / 100) [V] (1)

Further, assuming that the temperature coefficient of the linear temperature sensor 27 that converts a temperature change into a change in electrical resistance is β (% / ° C.) and the resistance value when ΔT = 0 is R ′ ₂ , the resistance value R of the linear temperature sensor 27 is ₂ is represented by R ₂ = R ′ ₂ (1 + ΔT · β / 100) (2)

Therefore, when the resistance value of the resistor 29 of the temperature compensation circuit shown in FIG. 7 and R _1, the relationship of the output voltage e _i and the magnetic encoder output voltage e _o of the MR element 20 and 21, It is represented by According to the equation (3), satisfies the conditions of (1 + ΔT · α / 100 ) (1 + ΔT · β / 100) = 1 ... (4), the output voltage e _o of the magnetic encoder is stable with respect to temperature You can see that.

In Figure 8, assuming that α = -0.4% / ℃, as 100% output voltage e _o of the magnetic encoder when the [Delta] T = 0, the relative output e _o, [Delta] T, the beta = 0 showing the relationship between the beta The characteristic is the output voltage of the magnetic encoder without temperature compensation, ΔT = 50 ° C
In the case of, the relative output change is as high as 20%. Also, β = + 0.
If 4% / ° C. is selected, the left side of equation (4) is 1 + ΔT ² · α · β / 10000. If ΔT is small, it can be omitted as ΔT ² · α · β / 10000 ≒ 0, but ΔT is large. case, which can not be omitted if [Delta] T ^2, relative output change in [Delta] T = 50 ° C. 4
%become.

Therefore, it can be seen that the temperature coefficient β of the linear temperature sensor 27 is determined by the operating temperature range of the magnetic encoder, and it is preferable to select the temperature coefficient β so that the minimum relative output change occurs within the operating temperature range. For example, when used at ΔT = 50 ° C., β = 0.5% / ° C. as shown in FIG.
, The relative output change can be suppressed to 1.25%.

Therefore, in the present invention, a linear temperature sensor 27 having a temperature coefficient β selected so as to satisfy the condition of (1 + ΔT · α / 100) (1 + ΔT · β / 100) ≒ 1 is used. Thus, temperature compensation is performed.

Next, the contact surface between the MR element deposition substrate and its supporting structure,
And the joining of both members will be described.

FIGS. 11 to 13 show the support structure 16 of the MR element deposition substrate 18.
As shown in the figure, an alignment surface 36, a groove 38, and a contact surface 39 of the MR element deposition substrate 18 are provided. The groove 38,
As shown in FIG. 11, along the alignment surface 36 It is formed in a mold. An adhesive 40 is applied to the contact surface 39 as shown by hatching in FIG.

On the other hand, as shown in FIG. 9, a positioning surface 37 is provided on the MR element deposition substrate 18.

The alignment surfaces 36 and 37 are processed with high precision parallel or perpendicular to the MR element group 19.

Then, after applying the adhesive 40 to the contact surface 39 of the support structure 16, the positioning surface provided on the support structure 16 is provided.
36, an alignment surface 37 provided on the MR element deposition substrate 18 is brought into contact with and adhered thereto, and as shown in FIGS. 14 and 15,
The MR element deposition substrate 18 is integrally bonded and joined to the support structure 16.

During this bonding, the excess adhesive 40 applied to the contact surface 39 flows into the groove 38 and does not adhere to the alignment surfaces 36 and 37, so that the support structure 16 and the MR element deposition substrate 18 can be easily and easily connected. Positioning can be performed with high accuracy.

In addition, by providing the groove 38, especially the support structure
The processing of the corners of the 16 alignment surfaces 36 can be easily performed.

Next, a description will be given of a coupling structure of the support structure of the MR element deposition substrate and the end bracket which is the support structure of the magnetic recording medium.

As shown in FIGS. 16 and 17, the end bracket 1 has a contact surface 41 of the MR element vapor-deposited substrate 18 with the support structure 16,
A groove 43 and a screw hole 45 are provided. The contact surface 41
Are formed on both sides of the groove 43 and are processed with high precision. The two screw holes 45 are provided at predetermined intervals.

As shown in FIG. 12, the support structure 16 of the MR element deposition substrate 18 has a contact surface 42 with the end bracket 1, a groove 44,
A screw hole 46 is provided. The contact surface 42 is processed so as to be in close contact with the contact surface 41 provided on the end bracket 1 with high precision. The groove 44 is a support structure
The contact surface 42 provided on the 16 is provided so as to be divided into four. Two screw holes 46 are provided in alignment with the screw holes 45 provided in the end bracket 1.

Then, the contact surface 41 provided on the end bracket 1 which is a support structure of the magnetic recording medium 12 is provided on the MR element evaporation substrate 18.
1. The contact surface 42 provided on the support structure 16 of FIG. 1 is brought into contact, the screw 17 shown in FIG. 1 is passed through the screw through hole 46, and this screw 17 is screwed into the screw hole 45. The 18 support structures 16 are screwed.

By the way, if the contact surface between the end bracket 1 and the support structure 16 is screwed without providing a groove, the contact surfaces come into contact with a large area, and the influence of the unevenness of the contact surfaces appears. For example, when the materials of the end bracket 1, the support structure 16, and the screw 17 have different coefficients of linear expansion, thermal stress occurs when the temperature changes during use, and the support structure has a support point at the apex of the convex portion of the contact surface. Since 16 tilts, the positions of the MR element deposition substrate 18 and the magnetic recording medium 12 relatively change. Also in the screw tightening operation, the position of the MR element vapor deposition substrate 18 and the magnetic recording medium 12 relatively changes with the apex of the convex portion of the contact surface as a fulcrum due to the stress fluctuation during the tightening. As a result, the amplitude of the output signal of the magnetic encoder, the pulsation of the amplitude, and the waveform distortion change. Therefore, the performance of the magnetic encoder largely depends on the quality of the positioning of the MR element vapor deposition substrate 18 and the magnetic recording medium 12.

Therefore, in this embodiment of the present invention, FIGS.
As shown in the drawing, a groove 43 is provided between the contact surfaces 41 of the end bracket 1, and as shown in FIG. 12, a groove 44 is provided on the contact surface 42 of the support structure 16 of the MR element deposition substrate 18. Since the contact surface 44 of the support structure 16 of the MR element vapor deposition substrate 18 contacts the contact surface 41 of the end bracket 1 at four divided locations, the thermal stress of the contact surfaces 41 and 42 changes. However, the influence of the uneven portions of the contact surfaces 41 and 42 is small, and the change in the position between the MR element deposition substrate 18 and the magnetic recording medium 12 can be suppressed to a small value. Further, even if there is a stress variation during the screw tightening operation, a change in the position between the MR element deposition substrate 18 and the magnetic recording medium 12 due to the influence of the uneven portions of the contact surfaces 41 and 42 can be suppressed. Thus, a stable output signal of the magnetic encoder can be obtained.

In addition, by providing the grooves 43, 44 in the contact surfaces 41, 42, the area of the contact surfaces can be reduced, and the processing is made easier.

 Next, various other embodiments of the present invention will be described.

The support structure 16 of the MR element deposition substrate 18 is made of brass (linear expansion coefficient = 19 × 10 ⁻⁶ / deg, Young's modulus = 11000 kg / mm ² ) or ceramic (linear expansion coefficient = 9.4 × 10 ⁻⁶ / deg, Young's modulus = 6700
kg / mm ² ), linear resistance change rate characteristics as shown in FIGS. 4 and 5 can be obtained. When the thermal stress is calculated by the combination model shown in FIG. 3.2 kg / mm ² when formed, 1.2 when formed of ceramic
the kg / mm ^2.

FIGS. 4 and 5 show a sandwich structure in which a soft material capable of absorbing thermal stress is sandwiched between the MR element deposition substrate 18 and the support structure 16 thereof, and are bonded with an adhesive. The linear resistance change rate characteristic as shown in FIG.

Further, in the present invention, the support structure 16 of the MR element
And the end bracket 1 as a support structure of the magnetic recording medium 12 are brought into contact with each other at three or more partial contact surfaces that are spaced from each other, and are screwed. It can be kept low.

FIG. 20 shows another embodiment of the present invention.
It is the partially broken perspective view which simplified and showed the internal mechanism.

In the embodiment shown in FIG. 20, the linear temperature sensor 27
The MR element evaporation substrate 18 and the magnetic recording medium 12 are arranged at a position showing the same temperature as the vicinity of the position / speed detection section, and the MR element evaporation substrate
Attached to 18. This makes it possible to obtain a temperature-compensated output signal from the magnetic encoder.

Other configurations of the embodiment shown in FIG. 20 are the same as those of the embodiment shown in FIGS. 1 to 3, and the same members are denoted by the same reference numerals.

Subsequently, FIG. 21 shows another embodiment of the present invention,
This is a magnetic encoder circuit.

In the magnetic encoder circuit shown in FIG.
The waveform shaping circuit 32 is connected to the temperature compensation circuit shown in the figure. In this embodiment, the output signal e _o of the magnetic encoder having a sine waveform processed by the temperature compensation circuit is used as the waveform shaping circuit 3.
By shaping the waveform in step 2, a pulse wave output with a reduced duty change due to a temperature change can be obtained.

The other configuration of the magnetic encoder circuit shown in FIG. 21 is the same as that of the embodiment shown in FIG. 7, and the same members are denoted by the same reference numerals.

In the embodiment shown in the drawings, the magnetic recording medium 12 is described as having a multi-pole magnet. However, the present invention can be applied to a magnetic recording medium 12 having a one-pole magnet for detecting a reference position. .

In this embodiment, the magnetic rotary encoder has been described, but the same effect can be obtained with a magnetic linear encoder.

In the present embodiment, the drum type having the magnet on the circumferential end surface of the magnetic recording medium has been described. However, the same effect can be obtained with the disk type encoder having the magnet on the disk surface of the magnetic recording medium.

[Effects of the Invention] According to the present invention, the MR element deposition substrate and its supporting structure are made of a material capable of suppressing the thermal stress generated at the joint between the two members. As a result of maintaining the linearity of the rate characteristic, even when used in an environment having a temperature change, highly accurate temperature compensation of the output signal of the MR element can be performed. Moreover, since the MR element deposition substrate and its supporting structure are bonded by a soft adhesive capable of absorbing thermal stress, the thermal stress generated between the MR element deposition substrate and its supporting structure can be absorbed. Since the magnetostriction of the MR element caused by the thermal stress of both members can be prevented, the linearity of the resistance change rate temperature characteristic of the MR element can be kept good. When the temperature characteristic of the output voltage of the MR element is α, the temperature coefficient of the linear temperature sensor is β, and the amount of temperature change is ΔT, the linear temperature sensor has (1 + ΔT · α / 100) (1 + ΔT · β / 100) ≒
Since the temperature coefficient β selected so as to satisfy the condition 1 is used, the output voltage of the magnetic encoder can be stabilized with respect to the temperature, and the temperature coefficient selected so as to satisfy the above condition can be further stabilized. The β linear temperature sensor detects the temperature near the position and speed detection of the MR element and the magnetic recording medium, and amplifies the detected temperature with an amplifier circuit to compensate for the temperature. Detection becomes possible. Together, these effects provide an effect that the position and speed of the object can be detected with high accuracy even in an environment having a temperature change.

Further, according to the present invention, the linear temperature sensor is provided at a position having the same temperature as the position near the position / speed detecting unit of the MR element and the magnetic recording medium, and the present invention is also used in an environment having a temperature change. In this case, the position and speed of the object can be detected with high accuracy.

Further, according to the present invention, a groove for inflow of the adhesive is provided on the bonding surface of the MR element vapor deposition substrate in the support structure of the MR element vapor deposition substrate, and excess adhesive flows into the groove.
The element deposition substrate and its supporting structure can be positioned easily and with high accuracy, and the position / speed detection accuracy of the object can be improved.

[Brief description of the drawings]

1 to 17 show an embodiment of the present invention.
FIG. 1 is a longitudinal side view of the entire magnetic encoder, FIG. 2 is a front view of FIG. 1 as viewed from the line II-II, and FIG. 3 is III-I of FIG.
FIG. 4 is a cross-sectional view taken along the line II, FIG. 4 and FIG. 5 are temperature diagrams of resistance change rate of the MR element, FIG. 6 is a junction model diagram of the MR element deposition substrate and its supporting structure, FIG. FIG. 8 is a diagram showing the relationship between the relative output voltage of the magnetic encoder and the amount of temperature change, FIG. 9 is an enlarged plan view of the MR element deposition substrate, FIG. 10 is a side view of FIG. 9, and FIG. FIG. 12 is a plan view of the support structure of the element deposition substrate, FIG. 12 is a view seen from the XII-XII line side of FIG.
13 is a side view of FIG. 11, FIG. 14 is an enlarged plan view showing a coupling state between the MR element and its supporting structure, FIG. 15 is a side view of FIG. 14, and FIG. 16 is a magnetic recording medium. FIG. 4 is a view of an end bracket, which is a support structure of FIG.
FIG. 17 is a sectional view taken along the line XVII-XVII in FIG. 18 and 19 are temperature diagrams showing the resistance change rate of the MR element when the MR element and its supporting structure are formed of materials having different linear expansion coefficients. FIG. 20 shows another embodiment of the present invention, and is a partially cutaway perspective view showing the internal mechanism in a simplified manner, and FIG. 21 shows another embodiment of the present invention, which is a magnetic encoder circuit. is there. DESCRIPTION OF SYMBOLS 1 ... End bracket, 2 ... Case, 6 ... Shaft, 12 ... Magnetic recording medium, 13 ... Magnet, 14,15 ...
... Rotating, fixed shield plate, 16 ... Support structure for MR element deposition substrate, 17 ... Screw, 18 ... MR element deposition substrate, 19 ... MR
Element group, 20,21… MR element, 24… Amplifier circuit printed circuit board, 27… Linear temperature sensor, 29,30… Temperature compensation circuit resistor, 31… Amplifier, 32 …… Waveform shaping circuit, φ ₁ ,
φ ₂ ... magnetic flux of signal magnetic field, 36, 37 ... alignment surface, 38 ...
... groove, 39 ... contact surface, 40 ... adhesive, 41, 42 ... contact surface, 43, 44 ... groove.

Claims (3)

(57) [Claims] An object of the present invention is to provide a magnetoresistive element vapor-deposited substrate and a supporting structure thereof so that the temperature coefficient of the magnetoresistive element is linear.
It is formed of a material capable of suppressing the thermal stress generated at the junction between the magnetoresistive element deposited substrate and the support structure, and the magnetoresistive element deposited substrate and the support structure are heat-bonded to each other. The temperature characteristic of the output voltage of the magnetoresistive element is α, the temperature coefficient of the linear temperature sensor near the speed detector is β,
When the temperature change amount is ΔT, (1 + ΔT · α / 100)
A magnetic encoder characterized in that a temperature compensation is performed by a linear temperature sensor having a temperature coefficient β selected to satisfy the condition of (1 + ΔT · β / 100) ≒ 1 and an amplifier circuit. 2. The magnetic encoder according to claim 1, wherein the linear temperature sensor is provided at a position at which the temperature becomes the same as the position near the position / speed detecting section of the magnetoresistive element and the magnetic recording medium. 3. The method according to claim 1, wherein a groove for injecting an adhesive is provided on a contact surface of the supporting structure of the magnetoresistive element deposited substrate with the magnetoresistive element deposited substrate. Magnetic encoder.