JPS62115317A - Position detector - Google Patents

Abstract

PURPOSE:To accurately detect a turning angle and the mobile position of a movable body by eliminating the influence by the outside air temperature which magneto-resistance elements receive and outputting a highly precise position detection signal. CONSTITUTION:The 1st and the 2nd detection means 13 and 14 consisting of a couple two each of magneto-resistance elements 13A, 13B, 14A and 14B are provided to a permanent magnet 12 and arranged so as to be opposed to the specified position 1A of the movable body 1. Then, the 1st and the 2nd threshold level setting means 19 and 20 set threshold levels of detected signals outputted from the detection means 13 and 14. Next, the 1st and the 2nd comparison means 21 and 22 compare the levels of the detected signal from the means 13 and 14 with the set levels by the means 19 and 20 respectively. Then, a position detection signal output means 23 outputs a position detection signal when the signals outputted from the means 21 and 22 are both identical.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a positioning system used to detect one specific position or a plurality of specific positions provided on a movable body such as a rotating body or a linearly moving body. This invention relates to a detection device.

[Prior art]

Generally, devices with rotating bodies such as rotary stages and front disc devices require a home position signal of one pulse per rotation, and reciprocating devices such as hydraulic and pneumatic cylinder devices require a home position signal of one pulse per rotation. Also requires a stroke end detection signal to detect the stroke end.

For this reason, in the prior art, rotational position detection devices shown in FIGS. 8 to 1O are known.

In the figure, reference numeral 1 denotes a rotating body that rotates clockwise CW or counterclockwise ccw -, and the rotating body 1 is made of a magnetic material such as ferrite, permalloy, pure iron, etc., and has a protrusion on its outer circumferential surface that indicates a specific position. LA is provided. Reference numeral 2 denotes a rotation sensor, and the rotation sensor 2 includes a permanent magnet 3 that applies a magnetic bias, and is provided on the N-pole side magnetized surface of the permanent magnet 3 facing the circumferential surface of the rotating body 1 and spaced apart by a predetermined distance. It is composed of two magnetoresistive elements 4.5, and the distance between the mounting positions a and b of each magnetoresistive element 4.5 is approximately the same as, for example, the projection IA. Each of the magnetoresistive elements 4.5 is a ninth magnetoresistive element.
As shown in the figure, they are connected in series and have a voltage of +Vi between terminals 6 and 7.
n is applied, and the output voltage Vout is derived from the output terminal 8 between the magnetoresistive elements 4.5.

Here, the resistance value of the magnetoresistive element 4.5 changes depending on the magnetic flux component perpendicular to the magnetic sensing surface of the element, and when the protrusion IA faces the magnetoresistive element 4 or 5 as the rotating body 1 rotates, Since the magnetic field from the permanent magnet 3 exits to the protrusion IA almost orthogonally to the element's magnetic sensing surface, the resistance value of the magnetoresistive element 4.5 is highest in this state. Therefore, due to the change in resistance of the magnetoresistive elements 4 and 5, the output voltage V from the output terminal 8
As shown in FIG. 10, out is lowest at the mounting position a of the magnetoresistive element 4 and highest at the mounting position a of the magnetoresistive element 5, making it possible to obtain a stable output voltage.

[Problem that the invention seeks to solve]

However, due to their sensitivity characteristics, the magnetoresistive elements 4 and 5 have a property that as the outside temperature increases, the rate of change in resistance value becomes smaller. Therefore, in FIG. 10, if the output voltage characteristic at low temperature is Vout L shown by the solid line, the output voltage characteristic at high temperature is Vout L shown by the dashed line.
)l, and has the characteristic that the output amplitude at high temperatures becomes small.

As a result, when outputting a pulse signal by setting a predetermined threshold level V or v2 to obtain a home position signal by pulsating the output voltage Vout H or Vout L, if we consider the threshold level V, , the pulse at high temperature reaches rHJ level in section ll (, and the pulse at low temperature reaches rH level in section !!,
It will be J level. Therefore, there is a problem that the pulse width, rising position, and falling position are different between high temperature and low temperature, making it impossible to output an accurate home position signal.

The present invention has been made in view of these problems, and an object of the present invention is to provide a position detection device that can detect the rotational position or movement position of a movable body with high precision without being affected by the outside temperature. be.

[Means for solving problems]

In order to solve the above problems, the feature of the configuration adopted by the present invention is that a first magnetoresistive element is provided on a permanent magnet and is composed of a pair of two magnetoresistive elements arranged to face a specific position of the movable body. ．． A second detection means and a first detection means for setting a threshold level of a detection signal output from each detection means.
a second threshold level setting means;
．． The first step compares the level of the detection signal from the second detection means with the level set by each threshold level setting means. The present invention is comprised of a second comparison means and a position detection signal output means for outputting a position detection signal when the signals outputted from each comparison means match.

〔Example〕

Embodiments of the present invention will be described below with reference to FIGS. 1 to 7. Note that since there is no difference in the rotating body from the prior art, a description thereof will be omitted.

1 to 4 show a first embodiment of the invention.

In the same figure, 11 is a rotation sensor, and the rotation sensor element 11 is a rotation sensor.
is a permanent magnet 12 that provides a magnetic bias, and the permanent magnet 1
A first magnet is disposed on the N-pole side magnetized surface of the magnet 2, facing the circumferential surface of the rotating body 1, and having a phase difference in the rotational direction of the rotating body 1. It is composed of a second detection section 13 and 14. here,
Each detection unit 13° 14 has two magnetoresistive elements 13.
It consists of A, 138114A and 14B. and,
Each magnetoresistive element 13A, 13B, 14A, 14B is 13A-14A→
They are installed in the order of 13B → 14B.

Moreover, each magnetoresistive element 13A, 13B, 14A.

14B is two adjacent magnetoresistive elements 13A and 14A,
14A and 13B, and 13B and 14B are respectively attached to positions covered by the protrusion IA of the rotating body 1 at the same time.

Therefore, the width dimension of the projection IA in the rotational direction is d, and each of the magnetoresistive elements 13A and 14A.

If the mounting positions of 13B and 14B are A, B, C, and D,
The dimensions between AB, BC, and CD are all set to d/2. In addition, in this embodiment, reducing the interval between BC leads to an improvement in position detection accuracy, and in practice, the width dimension d in the rotational direction of the protrusion IA and the dimensions between AC and BD are substantially Just make them equal values.

Further, each of the detection units 13, 14 has magnetoresistive elements 13A and 13B, 14A and 14B connected in series, respectively, as shown in FIGS. 2 and 3, and the series circuit is connected to the terminal 1.
5.16 is inserted in parallel, and voltage +Vi is applied from terminal 15.
By applying n, each magnetoresistive element 13A and 13
B, between 14A and 14B, that is, the first. Second detection unit 13
．． Output voltage Vout13 from output terminals 17 and 18 of 14
゜Vout14 is output. On this occasion,
Output voltage Vout 13. Vout 14 is the fourth
As shown in the figure (a), there is a phase difference of d/2.

FIG. 3 shows a configuration diagram of a position detection signal output circuit including each of the magnetoresistive elements. In the same figure, 19°20 is the 1st.
In the second threshold level setting circuit, each of the threshold level setting circuits 19 and 20 connects a series connection of resistors R, Rz, and Ri and R4 to terminals 15 and 15, respectively.
．． It is constructed by inserting it between 16. The threshold level setting circuits 19 and 20 set the respective threshold levels VT(19) and VT(20).
1, (A) Vout 13. At Vout 14, the no-signal level is both □Vin, so
and Vout 13. Vout 14 are each -
While it is larger than Vin, signals such as those shown in FIG. 4 (b) and FIG. 4 (c) are obtained.

Reference numerals 21 and 22 denote first and second comparator circuits composed of, for example, operational amplifiers. It is connected to the first threshold level setting circuit 19, and when the level of the output voltage is higher than the set level, it outputs an output pulse Vout 21 of the same level as the output voltage, as shown in FIG. 4(b). On the other hand, the second comparison circuit 22 has an inverting input terminal connected to the output terminal 18 of the second detection unit 14, and a non-inverting input terminal connected to the second threshold level setting circuit 20.
When the level of the output voltage is higher than the set level, an output pulse Vout22 having a level opposite to that of the output voltage is outputted as shown in FIG. 4(c).

23 is an AND circuit, and the input side of the AND circuit 23 is connected to the output terminals of each of the comparison circuits 21 and 22, and only when the output busses Vout21 and Vout22 from these circuits match, the output terminal 24 is connected to the output terminal 24 (FIG. 4). The position detection signal Vout23 shown in (d) is output as a pulse signal. Therefore, the AND circuit 23 constitutes a position detection signal output circuit according to this embodiment.

Furthermore, 25 is a play type flip-flop circuit, and the flip-flop circuit 25 has a data input terminal connected to the comparison circuit 21 and a clock input terminal connected to the comparison circuit 22.

Therefore, when a signal is input to the data input terminal and the clock input is reversed, the flip-flop circuit 25 outputs a reverse signal indicating counterclockwise rotation CCt+ from the output terminal α.

The present embodiment is configured as described above, and its operation will be described next.

Now, assuming that the rotating body 1 is rotating clockwise CW, the protrusion IA of the rotating body 1 is connected to the magnetic resistance elements 13A, 1.
13A-14A-13B for 3B, 14A, 14B
-14B, and each detection unit 13.
From 14, the output voltage Vout 13 shown in FIG. 4 (a)
．． Vout 14 is detected and output as a signal. The comparison circuit 212 compares this output voltage Vout13+Vout14.
2, the output terminal outputs the output as shown in Figure 4 (
b), output busle Vout 2 as shown in Figure 4(c)
1. Vout 22 is generated. Furthermore, these output pulses Vout21°Vout22 are connected to an AND circuit 23.
, the output terminal 24 outputs the position detection signal Vout23 shown in FIG.
23 is used as a home position signal, etc.

Now, the output voltage Vout 13 from the detection unit 13.14
+Vout 14 is the output voltage Vout 13t +Vo as shown by the solid line at low temperature, as in the conventional technology.
ut14L, but at high temperature the output voltage V as shown by the dotted line
out 13H, L 4H (see Figure 4 (a))
.

However, in the characteristic diagram of Fig. 4 (d), the output voltage Vout
13, the corresponding intermediate position P1 from the rLJ level is the magnetoresistive element 13A that constitutes the detection unit 13,
13B, that is, the mounting position B. As a result, at the intermediate position P+, each magnetoresistive element 13A
, 13B are affected by the same outside temperature, so they are the positions where the variation between the output voltage Vout 13L at a low temperature and the output voltage Vout 13□ at a high temperature is the smallest. On the other hand, when the protrusion IA of the rotating body 1 approaches the magnetoresistive element 13A or when the protrusion IA moves away from the magnetoresistive element 13B, a large variation occurs between the output voltages Vout 13t and Vout131. On the other hand, regarding the output voltage Vout 14, at the intermediate position Pt, the output voltage Vout 14L and Vou
t 14o is the smallest. Therefore, the output pulse Vout 21 has a rising characteristic and is little affected by the outside temperature, but a falling characteristic is greatly influenced by this.

On the other hand, the output pulse Vout22 has a falling characteristic and is less affected by the outside temperature.

Therefore, the position detection signal Vout2 from the AND circuit 23
3 utilizes the rising characteristic of the output pulse Vout21 with its rising characteristic, and uses the rising characteristic of the output pulse Vout2 with its falling characteristic.
2, the position detection signal Vout 23 can be a highly accurate pulse signal that is less affected by the outside temperature, as shown in FIG. 4(d). Therefore, when using this position detection signal as a home position signal etc., highly accurate control is possible.
Further, when the rotating body 1 is a rotating gear, pitch errors in the tooth profile can be tolerated, making it possible to provide a highly accurate rotation sensor.

Next, FIGS. 5 to 7 show a second embodiment of the present invention, in which the same components as those of the first embodiment described above are given the same reference numerals, and the explanation thereof will be omitted.

However, also in this embodiment, the rotation sensor 31 is placed opposite the permanent magnet 32 and the circumferential surface of the rotating body 1, and
The first one is arranged with a phase difference in the rotational direction. It is composed of second detection units 33 and 34. However, in this embodiment, the arrangement of each pair of magnetoresistive elements 33A and 33B, 34A and 34B constituting each detection section 33, 34 is 33A→34B→33 when viewed from the clockwise rotation CW of the rotating body 1.
The difference is that they are installed in the order of B-34A. Note that, compared to the first embodiment, the magnetoresistive elements 34A and 34B
The arrangement of is reversed.

On the other hand, each magnetoresistive element 33A and 33B, 34A and 34B
For series connection of terminals 15. to 15. as shown in FIG.
Magnetoresistive element 33A for between 16 and 16.

34A is located on the terminal 15 side, and voltage +Vin is applied thereto. Note that this embodiment is equivalent to the case where the series connection of the magnetoresistive elements 14A and 14B in the first embodiment is reversed, and the magnetoresistive element 14B is located on the terminal 15 side.

Therefore, looking at the output voltage of the rotation sensor 31 according to the 31st example, as shown in FIG. Output each. Note that this characteristic is compared to the first embodiment, and the output voltage V
out34 has a waveform characteristic that is line symmetrical with respect to the average voltage -V in .

Further, reference numerals 35 and 36 are first and second comparison circuits used in this embodiment, and the non-inverting input terminal side of each of these comparison circuits 35 and 36 is connected to the output terminal 17 and 18 of the detection section 33 and 34, The inverting input terminal side is connected to threshold level setting circuits 19 and 20. Therefore, the output pulses VouL 35.36 shown in FIGS. 7(B) and 7(C) are output from each comparison circuit 35.36 only when the level of the output voltage is higher than the set level. Output Vout 36. Thus, the AND circuit 23 outputs a position detection signal as shown in FIG. Outputs Vout23.

Although the present embodiment is configured as described above, the rising position of the output pulse Vout35 output from the comparator circuit 35 corresponds to the intermediate position p of the output voltage Vout33 (corresponding to the mounting position B' of the magnetoresistive element 34B). In addition, the falling position of the output pulse Vout36 output from the comparator circuit 36 is the intermediate position pz (
(corresponding to the mounting position C' of the magnetoresistive element 33B). As a result, the position detection signal Vou from the AND circuit 23
t23 can be a highly accurate signal that is not affected by outside temperature.

In each of the embodiments, the rotating body 1 is used as an example of the movable body, but it may also be a ring-shaped body such as a rond or a plate-shaped body such as a rack. Furthermore, although it has been described that the rotor 1 is provided with the protrusion IA indicating a specific position at only one location, it may be provided at a plurality of locations, or may be provided with tooth profiles over the entire circumference like a gear.

Further, the means for indicating a specific position is not limited to a protrusion, and may be one having a recess or a groove.In short, as long as an uneven shape is provided on the outer surface of the movable body at a position facing the detection means. You can also place a permanent magnet.

Furthermore, the arrangement of each of the detection units 13, 14 (33, 34) is not limited to the embodiment, and the output voltages from these units may generate output voltages with a phase difference such that the rHJ level sensor or rLJ level sensor overlaps. They should be placed in such a relationship.

Furthermore, the position detection signal output circuit is not limited to the embodiment, and of course may have various circuit configurations.

〔Effect of the invention〕

The position detection device of the present invention, as described in detail above, is configured to eliminate the influence of outside temperature on the magnetoresistive element and output a highly accurate position detection signal. , can accurately detect the moving position,
It is suitable for use as a home position signal, rotation speed detection signal, etc.

[Brief explanation of drawings]

1 to 4 relate to a first embodiment of the present invention, in which FIG. 1 is a configuration diagram showing a rotation sensor according to this embodiment, FIG. 2 is a wiring diagram of a magnetoresistive element, and FIG. 3 is a position diagram. The configuration diagram of the detection signal output circuit, Figure 4 is a waveform diagram, Figure 4 (a) is an output waveform diagram of each detection section, and Figure 4 (b) is an output waveform diagram from the first comparison circuit. , FIG. 4(c) is an output waveform diagram from the second comparison circuit, FIG. 4(d) is an output waveform diagram from the AND circuit, and FIGS. 5 to 7 are the second embodiment of the present invention. 5 is a configuration diagram showing a rotation sensor according to this embodiment,
Figure 6 is a configuration diagram of the position detection signal output circuit, Figure 7 is a waveform diagram, Figure 7 (a) is an output waveform diagram of each rotation sensor, and Figure 7 (b) is the first comparison circuit. Figure 7 (C) is an output waveform diagram from the second comparison circuit, Figure 7 (D) is an output waveform diagram from the AND circuit, and Figures 8 to 10 are related to the prior art. Accordingly, Fig. 8 is a configuration diagram of a rotation sensor according to the prior art, Fig. 9 is a wiring diagram of a magnetoresistive element, and Fig. 1
Figure 0 shows an output waveform diagram from the rotation sensor. 1... Rotating body (movable body), IA... Protrusion (specific position) 11.31... Rotation sensor, 12.32... Permanent magnet, 13.14, 33.34... Detection section , 13A. 13B, 14A, 14B, 33A, 3
3B. 34A, 34B... Magnetoresistive element, 19.20...
Threshold level setting time iW, 21, 22°3
5.36... Comparison circuit, 23... AND circuit.

Claims (1)

[Claims] In a position detection device for detecting one or more specific positions provided on a movable body, a pair of magnetic resistance elements provided on a permanent magnet and arranged to face the specific positions of the movable body. first and second detection means, first and second threshold level setting means for setting the threshold level of the detection signal output from each of the detection means, and the first and second detection means. first and second comparison means for respectively comparing the level of the detection signal from the threshold level setting means with the level set by each of the threshold level setting means, and outputting a position detection signal when the signals output from each of the comparison means match. 1. A position detection device comprising: position detection signal output means.