JPH0755455Y2 - Magnetic encoder zero point detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a zero point detection device for a magnetic encoder using a magnetoresistive element.

(Prior Art) Conventionally, as a magnetic encoder using a magnetoresistive element, for example, as shown in FIG. 4, a magnetic code recording member c having a zero-point detection magnet a and an incremental detection magnet b has both magnets a, A magnetic resistance element array pattern d for zero point detection and a magnetic resistance element array pattern (not shown) for incremental detection are provided, for example, on a glass substrate e so as to face b respectively.
Both of which are connected to each other, and the two arrangement patterns are connected to each other and are arranged along the tracks f of the magnets a and b. g ₁ g ₂ g ₃ g ₄ ), so that a zero point signal and an incremental signal are detected from the output terminal (h for zero point detection) of the connection circuit of the plurality of magnetoresistive elements according to the movement of the magnet. It is known that the zero point signal is converted into a zero point pulse through a comparator (not shown) for use.

(Problems to be solved by the invention) It is desirable that the zero-point pulse of the magnetic encoder be stable against disturbances such as temperature and vibration. However, according to the conventional magnetic encoder, the magnetoresistive element g ₁ When the zero point signal e _a output from the output terminal h of the connection circuit of ~ g ₄ is superimposed with noise e _n as shown in FIG. 5 (A) or the amplitude changes like the zero point signal e _b , There is a problem that the pulse width of the zero-point pulse p output from the comparator (not shown) changes from w ₁ to W ₂ or W ₃ as shown in FIG. 5 (B) and the zero-point pulse becomes unstable. .

It is an object of the present invention to provide a zero point detection device for a magnetic encoder that eliminates the above-mentioned conventional inconveniences.

(Means for Solving the Problems) In order to achieve the above object, the present invention comprises a zero point detecting magnet and a plurality of magnetoresistive elements that change the resistance value by detecting the magnetism of the zero point detecting magnet. A zero-point detecting device of a magnetic encoder having a zero-point detecting magnetic resistance element array pattern and arranged so that the zero-point detecting magnets and the zero-point detecting magnetic resistance element array pattern can relatively move along a predetermined moving line. The zero-point detecting magnetic resistance element array pattern includes two voltage dividers formed by connecting one end of the power supply side magnetic resistance and one end of the ground side magnetic resistance at one connection point,
The other ends of the power supply side magnetic resistors of the two voltage dividers are connected to each other, and the other ends of the ground side magnetic resistors are connected to each other,
The power supply side magnetic resistance and the ground side magnetic resistance of one of the voltage dividers are arranged along the longitudinal direction of the moving line, and the power supply side magnetic resistance of the one voltage divider and the other voltage divider are The ground side magnetic resistance is disposed symmetrically with respect to the moving line in a direction parallel to the width direction of the track of the zero point detecting magnet and perpendicular to the moving line, and the ground side magnetic resistance of the one voltage divider is arranged. The resistance and the magnetic resistance on the power supply side of the other voltage divider are arranged symmetrically with respect to the moving line in a direction parallel to the width direction of the track of the zero point detecting magnet and perpendicular to the moving line. Apply voltage to two voltage dividers and
The connection points of the two voltage dividers are connected to the input terminals of the subtraction means for outputting the zero-point signal.

(Operation) A zero-point detecting magnet and a zero-point detecting magnetic resistance element array pattern composed of a plurality of magnetic resistance elements whose resistance changes by detecting the magnetism of the zero-point detecting magnet are arranged along a predetermined moving line. Since the magnets are arranged so that they can move relative to each other, the magnetic resistance of the magnetoresistive element changes only when the zero-point detecting magnet approaches the magnetoresistive element.

The zero-point detecting magnetic resistance element array pattern includes two voltage dividers formed by connecting a power supply side magnetic resistance and a ground side magnetic resistance at one connection point, and the power supply included in the two voltage dividers. The other end of the side magnetic resistance is connected to each other, and the other ends of the ground side magnetic resistances are connected to each other, and the power supply side magnetic resistance and the ground side magnetic resistance of one of the voltage dividers are connected to the length of the moving line. The magnetic resistance on the power supply side of the one voltage divider and the magnetic resistance on the ground side of the other voltage divider are arranged parallel to the width direction of the track of the zero point detection magnet with respect to the moving line. Arrange it in a direction that is perpendicular to the movement line,
The ground side magnetic resistance of the one voltage divider and the power supply side magnetic resistance of the other voltage divider are parallel to the moving line and are perpendicular to the moving line of the track of the zero point detecting magnet. Since the magnets for zero-point detection pass near the two voltage dividers when a voltage is applied to the two voltage dividers, the connection points of the two voltage dividers are Output signals in opposite phases. When indicating this specifically, the two voltage divider outputs, for example, FIG. 3 (A) and the signal e ₁ antiphase as shown in (B), e _2, the output signal e _1, e ₂ Is added by the subtracting means and the zero point signal e ₀ having a large amplitude is output from the means as shown in FIG. 3 (C). Inclination angle theta ₀ of the zero-point signal e ₀ is from the smaller inclination angle theta _a conventional zero point signal e _a, the change of the pulse width of the zero point pulse due to a change in the amplitude of the zero point signal of the present invention is less than that of the prior art, A stable zero-point pulse is obtained. Further, even if the noise pulses en ₁ and en ₂ having the same phase are superimposed on the signals e ₁ and e ₂ output from both array patterns, the subtraction means to which the signals e ₁ and e ₂ are input causes the nozzle pulses en _{1 and} , En ₂ cancel each other out, and the zero signal
Erased from e ₀ . Thus, the pulse width of the zero-point pulse is relatively stable against disturbance.

(Embodiment) An embodiment of the present invention will be described with reference to the drawings.

In FIG. 1, reference numeral 1 denotes a zero-point detecting magnet, and the magnet 1 is, like the conventional one, an incremental detecting magnet (not shown) and a magnet for moving freely in a direction indicated by an arrow indicating a predetermined moving line. A code recording member is configured. One voltage divider 81 is constituted by the zero resistance detecting magnetic resistance element array pattern 41. The voltage divider 81 is a magnetic resistance that constitutes a magnetic resistance on the power supply side.
2 ₁ a and 2 ₁ b and the magnetic resistance 2 that constitutes the ground side magnetic resistance
₁ c, 2 ₁ d and these magnetic resistances 2 ₁ a, 2 ₁ b, 2 ₁
c, 2 in ₁ d a zero of the track 3 of the detecting magnet 1 width, and the zero-point detection magnet 1 is arranged along the longitudinal direction of the predetermined movement line moving. Another voltage divider 8 ₂ is constituted by the magnetic resistance element array pattern 4 ₂ for zero point detection. Voltage divider 8 _2,
A magnetoresistive ₂ 2 a, 2 2 b constituting the power supply side magnetoresistance, comprising a magnetoresistive ₂ 2 c, 2 2 d constituting the ground side magnetoresistance.

The power source side magnetic resistance of the _one voltage divider 4 ₁ and the ground side magnetic resistance of the other voltage divider 4 ₂ are symmetrical and perpendicular to the moving line, and further, the one voltage divider 4 ₂ The ground side magnetic resistance and the power supply side magnetic resistance of the other voltage divider 4 ₂ are symmetrical and perpendicular to the moving line, and the magnetic resistances 2 ₂ a, 2 ₂ b, 2 ₂ c, 2 ₂ d is arranged within the width of the track 3 of the zero-point detecting magnet 1 so as to be along the longitudinal direction of the moving line. Magneto-resistive elements with these arrangement patterns 4 ₁ and 4 _{2
2 1 a, 2 1 b,} 2 1 c, 2 1 d and _{2 2 a, 2 2 b,} 2 2 c, 2 2 d
Are mounted on a glass substrate 5, for example, which is provided at a predetermined distance from the magnetic code recording member together with a magnetic resistance element for incremental detection (not shown), and is connected as shown in FIGS. 1 and 2. It is connected to the power supply terminal 6 and the ground 7. Thus, the voltage divider _81, a connection point of the power supply side magnetoresistance composed of magnetoresistive element 2 ₁ a, 2 ₁ b, and the ground-side magnetoresistive composed of magnetoresistive 2 ₁ c, 2 ₁ d The signal output from 9 ₁ and the magnetic resistance of the voltage divider 8 _{2 on} the power supply side composed of the magnetic resistance elements 2 ₂ a and 2 ₂ b, and the magnetic resistance.
₂ 2 c, 2 2 connection point and the ground side magnetoresistive composed d 9 ₂
The signals output from the output terminals have opposite phases to each other as shown in FIGS. 3 (A) and 3 (B).

The connection point 9 ₁ and 9 ₂ + and terminals of example the differential amplifier 10 as a subtracting means - is connected to the terminal. Thus, the connection point from the output terminal of the differential amplifier 10 as shown in FIG.
A zero-point signal with a large amplitude is output by adding the input signals from 9 ₁ and 9 ₂ . This zero point signal is converted into a zero point pulse by the comparator 11.

(Effect of the Invention) As described above, according to the present invention, even if the level of the output signal output from the connection point of the voltage divider composed of the magnetoresistive element or the reference level of the comparator changes due to disturbance, the zero point signal or the zero point is generated. The pulse has the effect of being relatively stable.

[Brief description of drawings]

1 is a plan view of an essential part of one embodiment of the present invention, FIG. 2 is a circuit diagram thereof, FIG. 3 is a waveform diagram of each part of the circuit of FIG. 2, and FIG.
FIG. 5 is a perspective view of the main part of the conventional example, and FIG. 5 is a waveform diagram of that shown in FIG. 1 ... zero point detecting magnet _{2 1 a, 2 1 b,} 2 1 c, 2 1 d, 2 2 a, 2 2 b, 2 2 c, 2 1 d ... magnetoresistive element 4 _1, 4 ₂ ... zero point detection Magnetoresistive element array pattern 8 ₁ , 8 ₂ ... Voltage divider 9 ₁ , 9 ₂ ... Connection point 10 ... Differential amplifier 11 ... Comparator

Claims (1)

[Scope of utility model registration request] 1. A zero-point detecting magnetic resistance element array pattern comprising a zero-point detecting magnet and a plurality of magneto-resistive elements whose resistance changes by detecting the magnetism of the zero-point detecting magnet. A zero point detection device of a magnetic encoder, wherein the magnet and the zero point detection magnetic resistance element array pattern are arranged so as to be able to move relative to each other along a predetermined moving line, wherein the zero point detection magnetic resistance element array pattern is a power source. Two voltage dividers are formed by connecting one end of the side magnetic resistance and one end of the ground side magnetic resistance at one connection point, and connect the other ends of the power supply side magnetic resistances of the two voltage dividers, The other end of the ground side magnetic resistance is connected to each other, and the power supply side magnetic resistance and the ground side magnetic resistance of one of the voltage dividers are arranged along the longitudinal direction of the moving line, and Power supply side magnetic resistance of voltage divider The ground side magnetic resistance of another voltage divider is arranged symmetrically with respect to the moving line in a direction parallel to the width direction of the track of the zero point detecting magnet and perpendicular to the moving line, The magnetic resistance on the ground side of the voltage divider and the magnetic resistance on the power supply side of the other voltage divider are symmetrical with respect to the moving line in a direction parallel to the width direction of the track of the zero point detecting magnet and perpendicular to the moving line. A zero-point detecting device for a magnetic encoder, wherein the zero-point detecting device of the magnetic encoder is arranged so that a voltage is applied to the two voltage dividers, and the connection points of the two voltage dividers are connected to the input terminals of the subtracting means for outputting a zero-point signal.