JPH0445087B2 - - Google Patents

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 floppy disk 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. A stroke end detection signal is required to detect the stroke end.

For this reason, in the prior art, rotational position detection devices shown in FIGS. 8 to 10 are known.

In the diagram, 1 is clockwise CW or counterclockwise
The rotating body 1 is a rotating body that rotates CCW, and is made of a magnetic material such as ferrite, perlerloy, pure iron, etc., and has a protrusion 1A on its outer circumferential surface that indicates a specific position. 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 magnetoresistive elements 4,
The distance between the mounting positions a and b of 5 is, for example, approximately the same size as the projection 1A. The magnetoresistive elements 4 and 5 are connected in series as shown in FIG. 9, a voltage +Vin is applied between the terminals 6 and 7, and an output voltage Vout is derived from the output terminal 8 between the magnetoresistive elements 4 and 5. It is becoming more and more common.

Here, the resistance value of the magnetoresistive elements 4 and 5 changes depending on the magnetic flux component perpendicular to the magnetic sensing surface of the element, and as the rotating body 1 rotates, the protrusion 1A faces the magnetoresistive element 4 or 5. Then, since the magnetic field from the permanent magnet 3 exits to the protrusion 1A almost perpendicular to the element's magnetic sensing surface, the resistance values of the magnetoresistive elements 4 and 5 become the highest in this state. Therefore, the magnetoresistive element 4,
Due to the change in resistance of 5, the output voltage from output terminal 8
As shown in FIG. 10, Vout is lowest at the mounting position a of the magnetoresistive element 4 and highest at the mounting position b 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 the rate of change in resistance value decreases when the outside temperature becomes high. 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 _H shown by the dashed line, and the output amplitude at high temperature is small. have.

As a result, when outputting a pulse signal by setting a predetermined threshold level v ₁ or v ₂ to obtain a home position signal by pulsing the output voltage Vout _H or Vout _L , suppose that the threshold level v Regarding ₁ , the high temperature pulse becomes the "H" level in the interval _lH , and the low temperature pulse becomes the "H" level in the interval _lL . Therefore, there is a problem that the pulse width, rise position, and fall position differ between high and low temperatures, 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 configuration adopted by the present invention includes a movable body made of a magnetic material and provided with convex portions or grooves at one or more specific positions, and a permanent magnet provided with the movable body. a first pair of magnetoresistive elements arranged to face a specific position of the movable body and spaced apart by a distance approximately equal to the width dimension in the moving direction of the convex portion or groove of the movable body; , a 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 from the first and second detection means. first and second comparison means for respectively comparing the level of the detection signal of the detection signal with the level set by the respective threshold level setting means; and a position detection signal output means for outputting a position detection signal when both signal states coincide with each other, the first and second detection means having a pair of magnetoresistive elements connected in series. The intermediate position thereof forms an output terminal, and the first and second detecting means are connected in parallel between terminals to which a voltage is applied, and the magnetoresistive elements of the first and second detecting means are With respect to the moving direction of the movable body, the magnetoresistive element of the first detection means, the magnetoresistive element of the second detection means, the magnetoresistive element of the first detection means, and the magnetoresistive element of the second detection means. The reason is that they are arranged in order.

[Effect]

With this configuration, when the moving body moves, the first and second detection means detect 1/1/2 of the applied voltage.
A waveform detection signal is derived centered on 2, but
The intermediate position of this detection signal has a voltage that is 1/2 of the applied voltage, and is also the position where voltage fluctuations due to the influence of outside temperature are the smallest. Then, the detection signals from the first and second detection means are compared with the set level by the threshold level setting by the first and second comparison means, and an output pulse having a characteristic of rising and falling at a predetermined position is generated. occurs. Thereby, the position detection signal output means outputs a position detection signal when the output pulses output from the first and second comparison means match while detecting a convex portion or a groove of the movable body.

At this time, the first and second detection means are disposed so as to face the specific position of the movable body and are spaced apart by a distance approximately equal to the width dimension in the moving direction of the convex portion or groove of the movable body. The magnetoresistive element of the first detection means, the magnetoresistive element of the second detection means, and the magnetoresistive element of the first detection means in the moving direction of the movable body. , second
The magnetoresistive elements of the detection means are arranged in this order. As a result, when the position detection signal output means outputs the position detection signal, the range in which the output pulses match is the intermediate position of the detection signal from the first detection means and the intermediate position of the detection signal from the second detection means. It is possible to derive a position detection signal with the smallest voltage fluctuation due to the influence of outside temperature.

〔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 figure, 11 is a rotation sensor, and the rotation sensor 11 has a permanent magnet 12 that provides a magnetic bias.
and first and second detection units disposed on the N-pole side magnetized surface of the permanent magnet 12 facing the circumferential surface of the rotating body 1 and having a phase difference in the rotational direction of the rotating body 1. 13,
It consists of 14. Here, each detection unit 1
3 and 14 are respectively composed of two magnetoresistive elements 13A and 13B, and 14A and 14B. And each magnetoresistive element 13A, 13B, 14A, 1
4B is viewed from the clockwise rotation CW of the rotating body 1,
They are installed in the order of 13A → 14A → 13B → 14B. Moreover, each magnetoresistive element 13A, 13B,
14A and 14B are two adjacent magnetoresistive elements 1
3A and 14A, 14A and 13B, 13B and 14B
are respectively mounted at positions covered by the protrusions 1A of the rotating body 1. Therefore, the protrusion 1
The width dimension in the rotational direction of A is d, and each magnetoresistive element 13
A, 14A, 13B, 14B mounting position A,
Assuming B, C, and D, the dimensions between AB, BC, and CD are all set to d/2. In addition, in this example, reducing the interval between BC leads to improved position detection accuracy, and in practice, protrusion 1A
The rotation direction width dimension d and the dimensions between AC and BC may be set to substantially equal values.

Further, each of the detection units 13 and 14 is shown in FIGS. 2 and 3.
As shown in the figure, each magnetoresistive element 13A, 13B, 1
4A and 14B are connected in series, and
The series circuit is inserted in parallel between the terminals 15 and 16, and by applying the voltage +Vin from the terminal 15, the voltage between each magnetoresistive element 13A and 13B and between 14A and 14B, that is, the first and second detection parts 13 , 14 output voltage Vout13,
It is designed to output Vout14. On this occasion,
The output voltages Vout13 and Vout14 have a phase difference of d/2 as shown in FIG. 4A.

FIG. 3 shows a configuration diagram of a position detection signal output circuit including each of the magnetoresistive elements. In the same figure, 1
Reference numerals 9 and 20 denote first and second threshold level setting circuits, and each threshold level setting circuit 19 and 20 connects a series connection of resistors R ₁ and R ₂ and R ₃ and R ₄ to terminals 15 and 20, respectively. It is constructed by inserting it between 16. Note that the threshold level setting circuits 19 and 20 set the respective threshold levels V _{T (19)} and V _{T (20)} as V _{T (19)} =
It is determined by R ₂ /R ₁ +R ₂ ×Vin, V _T(20) =R ₄ /R ₃ +R ₄ ×Vin. At Vout13 and Vout14 in Fig. 4A, the no-signal level is both 1/2Vin, so
Set V _T(19) ≧Vin/2, V _T(20) ≧Vin/2, and while Vout13 and Vout14 are each larger than 1/2Vin,
The signals shown in FIG. 4B and FIG. 4C are obtained.

21 and 22 are, for example, first ports consisting of operational amplifiers;
In the second comparison circuit, the first comparison circuit 21 is connected to the non-inverting input terminal side and the output terminal 17 of the first detection section 13, and the inverting input terminal side is connected to the first threshold level setting circuit 19. connected,
When the level of the output voltage is higher than the set level, as shown in FIG. 4B, an output pulse Vout21 having the same level as the output voltage is output. On the other hand, the second comparison circuit 22 has its inverting input terminal side connected to the output terminal 18 of the second detection section 14, and its non-inverting input terminal side connected to the second threshold level setting circuit 20, so that the output voltage When the level of Vout2 is higher than the set level, as shown in Figure 4C, the output pulse Vout2 is at the opposite level to the output voltage.
Outputs 2.

23 is an AND circuit, the input side of the AND circuit 23 is connected to the output terminals of the respective comparison circuits 21 and 22, and output pulses Vout21 and Vout from these are connected.
22 match, the output from the output terminal 24 to the fourth
The position detection signal Vout23 shown in FIG. 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 delay 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 clock input terminal while a signal is input to the data input terminal, the flip-flop circuit 25 outputs a normal rotation signal indicating clockwise rotation CW from the output terminal Q. In the reverse state, the output terminal rotates counterclockwise.
Outputs a reverse signal indicating CCW.

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 1A of the rotating body 1 is 1
They face each other in the order of 3A→14A→13B→14B, and output voltages Vout13 and Vout14 shown in FIG. 4A are outputted as detection signals from each detection section 13 and 14. This output voltage Vout13, Vout1
4 is input to the comparator circuits 21 and 22, respectively.
Output pulses Vout21 and Vout22 as shown in FIG. 4B and FIG. 4C are generated from the output terminals.
Furthermore, these output pulses Vout21, Vout2
2 to the AND circuit 23, the output terminal 24
outputs a position detection signal Vout23 shown in FIG. 4D, and this signal Vout23 is used as a home position signal or the like.

Now, the output voltage Vout from the detection units 13 and 14
13. Vout14 is the output voltage VoutL as shown by the solid line at low temperature, as in the conventional technology,
However, when the temperature is high, the output voltages become _Vout13H and _Vout14H as shown by the dotted lines (see FIG. 4A).

However, in the characteristic diagram of Figure 4 D, the output voltage Vout
13, the intermediate position _P1 corresponding to the average voltage 1/2Vin for changing from the "L" level to the "H" level is the intermediate position of the magnetoresistive elements 13A and 13B that constitute the detection section 13, that is, the mounting position. It is in position B. As a result, at the intermediate position _P1 ,
Since each magnetoresistive element 13A, 13B is affected by the same outside temperature, it is located at the position where the variation between the output voltage _Vout13L at a low temperature and the output voltage _Vout13H at a high temperature is the smallest. On the other hand, the protrusion 1A of the rotating body 1 is connected to the magnetoresistive element 13A.
or when the protrusion 1A moves away from the magnetoresistive element 13B, the output voltage
A large variation occurs between _Vout13L and _Vout13H . On the other hand, regarding the output voltage Vout14, the variation between the output voltages _Vout14L and _Vout14H is the smallest at the intermediate position _P2 . Therefore, the output pulse
Vout21 has a rising characteristic and is less affected by the outside temperature, but a falling characteristic is greatly influenced by this.
Conversely, the output pulse Vout22 has a falling characteristic and is less affected by the outside temperature.

Therefore, the position detection signal from the AND circuit 23
Vout23 is the output pulse Vout due to its rising characteristic.
21 and the falling characteristic of the output pulse Vout22, the position detection signal Vout23 is a highly accurate pulse that is less affected by the outside temperature, as shown in FIG. 4D. It can be a signal. Therefore, when using this position detection signal as a home position signal, etc., highly accurate control is possible, and the rotating body 1
When the rotation gear is a rotating gear, a pitch error in the tooth profile can be tolerated, and a highly accurate rotation sensor can be obtained.

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 composed of a permanent magnet 32, and first and second detecting sections 33 and 34, which are arranged to face the circumferential surface of the rotating body 1 and have a phase difference in the rotational direction of the rotating body 1. . However, in this embodiment, each detection unit 33, 34
Each pair of magnetoresistive elements 33A each has a configuration of
The arrangement of 33B, 34A and 34B is 33A→34B→3 when viewed from the clockwise rotation CW of the rotating body 1.
The difference is that they are installed in the order of 3B → 34A.
Note that, compared to the first embodiment, the arrangement of the magnetoresistive elements 31A and 34B is reversed.

On the other hand, each magnetoresistive element 33A, 33B, 34A
For series connection of 34B and 34B, as shown in FIG.
A and 34A are located on the terminal 15 side, and voltage +Vin is applied thereto. Note that in this embodiment, the magnetoresistive elements 14A and 14A in the first embodiment are
The series connection of 14B is reversely connected, and the magnetic resistance element 1
This is equivalent to the case where 4B is located on the terminal 15 side.

Therefore, regarding the output voltage of the rotation sensor 31 according to this embodiment, as shown in FIG. do. Note that, compared to the first embodiment, this characteristic shows that the output voltage Vout34 is lower than the average voltage 1/2Vin.
It has waveform characteristics that are line symmetrical with respect to.

Furthermore, 35 and 36 are the first,
In the second comparison circuit, the non-inverting input terminals of these comparison circuits 35 and 36 are connected to the output terminals 17 and 18 of the detection units 33 and 34, and the inverting input terminals of these comparison circuits 35 and 36 are connected to the threshold level setting circuits 19 and 20, respectively.
is connected to. Therefore, each comparison circuit 35, 3
6 outputs output pulses Vout35 and Vout36 shown in FIGS. 7B and 7C only when the output voltage level is higher than the set level. Thus,
From the AND circuit 23, the "H" level section after the rise of the output pulse Vout35 and the output pulse
Only during the period of "H" level until the fall of Vout36, the position detection signal Vout as shown in FIG.
Outputs 23.

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 _P1 of the output voltage Vout33 (corresponding to the mounting position B' of the magnetoresistive element 34B). ,
Also, the output pulse output from the comparator circuit 36
Vout36 also falls at the output voltage Vout34
intermediate position P ₂ (mounting position of magnetoresistive element 33B)
C′). As a result, AND circuit 2
The position detection signal Vout23 from 3 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 shaft-shaped body such as a rod or a plate-shaped body such as a rack. In addition, although it has been described that the rotating body 1 is provided with only one protrusion 1A indicating a specific position,
It may be provided at a plurality of locations, or it 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 the detection units 13, 14 (33, 34) is not limited to the embodiment, and the output voltages from these units may have a phase difference such that the “H” level or “L” level overlaps with each other. They may be arranged in a relationship that generates an output voltage.

Furthermore, it goes without saying that the position detection signal output circuit is not limited to the embodiment and may have various circuit configurations.

〔Effect of the invention〕

As described in detail above, the position detection device of the present invention eliminates the influence of outside temperature on the magnetoresistive element and is configured to output a highly accurate position detection signal. , the moving position can be detected accurately, and it is suitable for use as a home position signal, a 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, Fig. 4 is a waveform diagram, and Fig. 4A is an output waveform diagram of each detection section.
Figure 4B is an output waveform diagram from the first comparison circuit, Figure 4C is an output waveform diagram from the second comparison circuit, and Figure 4C is an output waveform diagram from the second comparison circuit.
Figure D is an output waveform diagram from the AND circuit, Figures 5 to 7 relate to the second embodiment of the present invention, Figure 5 is a configuration diagram showing the rotation sensor according to the present embodiment, and Figure 6 is a diagram of the output waveform from the AND circuit.
The figure is a configuration diagram of the position detection signal output circuit, Figure 7 is a waveform diagram, Figure 7A is an output waveform diagram of each rotation sensor, Figure 7B is an output waveform diagram from the first comparison circuit, FIG. 7C is an output waveform diagram from the second comparison circuit, FIG. 7D is an output waveform diagram from the AND circuit, FIGS. 8 to 10 relate to the prior art, and FIG. FIG. 9 shows a configuration diagram of the sensor, FIG. 9 shows a wiring diagram of the magnetoresistive element, and FIG. 10 shows an output waveform diagram from the rotation sensor. 1... Rotating body (movable body), 1A... Protrusion (specific position), 11, 31... Rotation sensor, 12, 32
... Permanent magnet, 13, 14, 33, 34 ... Detection section, 13A, 13B, 14A, 14B, 33A,
33B, 34A, 34B... Magnetoresistive element, 1
9, 20... Threshold level setting circuit, 21, 22, 35, 36... Comparison circuit, 23
...AND circuit.

Claims (1)

[Claims] 1. A movable body made of a magnetic material and provided with protrusions or grooves at one or more specific positions;
A pair of permanent magnets are provided on a permanent magnet and are arranged so as to face a specific position of the movable body with a distance approximately equal to the width dimension in the moving direction of the convex portion or groove of the movable body. first and second detection means each comprising a magnetoresistive element; first and second threshold level setting means for setting a threshold level of a detection signal output from each of the detection means; first and second comparing means for respectively comparing the level of the detection signal from the second detecting means with the level set by each of the threshold level setting means; and a position detection signal output means for outputting a position detection signal when the signal states that indicate that a convex portion or a concave groove are detected coincide with each other,
The first and second detection means include a pair of magnetoresistive elements connected in series, with an intermediate position serving as an output terminal, and the first and second detection means are connected in parallel between terminals to which a voltage is applied. and said first,
The magnetoresistive element of the second detection means includes the magnetoresistive element of the first detection means, the magnetoresistive element of the second detection means, and the magnetoresistive element of the first detection means with respect to the moving direction of the movable body. , a position detecting device having a structure in which the magnetoresistive elements of the second detecting means are arranged in this order.