JP2021148447A - Position detection device - Google Patents

Abstract

To provide a position detection device capable of quickly determining an operation state of an object to be detected without changing the number of magnetic poles of a magnet.SOLUTION: A differential processing unit 41 differentiates a first detection signal Sa1 and a second detection signal Sa2 input from a first bridge circuit 11a and a second bridge circuit 11b, respectively. A signal processing unit 43 generates and outputs a control signal Srot capable of determining a low-speed or stopped operation state of an object to be detected based on a first differential signal Sr1 obtained by differentiating the first detection signal Sa1 and a second differential signal Sr2 obtained by differentiating the second detection signal Sa2. Based on the control signal Srot, a determination unit 44 determines whether or not the object to be detected is at the low speed or the stopped operation state.SELECTED DRAWING: Figure 5

Description

The present invention relates to a position detection device that detects the position of the object to be detected.

Conventionally, as this type of position detection device, a rotation detection device using a magnetic sensor in which four magnetoresistive elements are combined in a bridge shape is well known (see Patent Document 1 and the like). In this magnetic sensor, the resistance value changes according to the magnetic field applied to the magnetoresistive element, and a detection signal based on the detected magnetic field is output. Such a magnetic sensor is used, for example, when switching between two positions (on position and off position) of the object to be detected and when the position of the object to be detected is linearly detected.

Japanese Unexamined Patent Publication No. 2011-027495

Here, the detection signal output from the magnetic sensor may be converted into a pulse shape, and a rotational state such as low speed or stop of the detected object may be detected from the pulse signal. Specifically, for example, by monitoring the rise / fall of the pulse signal, the rotational state such as low speed or stop of the detected object is determined. However, in the case of this detection method, in order to quickly determine the operating state of the object to be detected, such as detecting a slower state or immediately determining a stop, the width of the pulse signal with respect to the rotation of the magnet It is necessary to increase the resolution to reduce the size. In this case, for example, it becomes necessary to increase the number of magnetic poles of the magnet, which leads to a problem of increasing the physique and cost of the product.

An object of the present invention is to provide a position detecting device capable of quickly determining an operating state of a detected body without changing the number of magnetic poles of a magnet.

The position detection device that solves the above problem is provided with a bridge pair having two bridge circuits in which magnetic resistance elements are assembled in a bridge shape, and a detection signal output from the bridge circuit as a waveform having a positive cosine relationship. Based on the above, the position of the object to be detected that moves integrally with the magnet that applies a magnetic field to the magnetic resistance element is detected, and the bridge pair or another bridge pair that is paired with the bridge pair has a positive cosine relationship. A differentiation processing unit that inputs the first detection signal and the second detection signal and differentiates them, a first differential signal obtained by differentiating the first detection signal, and a second detection signal obtained by differentiating the second detection signal. A signal processing unit that generates and outputs a control signal capable of determining the low speed or stop operating state of the detected object based on the second differential signal, and the control signal generated by the signal processing unit. Based on this, a determination unit for determining whether or not the detected object is in a low-speed or stopped operating state is provided.

According to the present invention, the operating state of the detected object can be quickly determined without changing the number of magnetic poles of the magnet.

The block diagram of the position detection device. Layout diagram of the sensor element of the magnetic sensor. Circuit diagram of the magnetic sensor. Waveform diagram of amplified signal and pulse signal. Electrical block diagram of the position detector. A timing chart showing changes in each signal when the object to be detected slows down or stops. An electric block diagram of another example position detector. The perspective view which shows the structure of the position detection apparatus of another example. The plan view of the position detection apparatus of FIG. FIG. 8 is a side view of the position detection device of FIG.

Hereinafter, an embodiment of the position detection device will be described with reference to FIGS. 1 to 6.
As shown in FIG. 1, the position detection device 1 is a rotation detection device 3 that detects the position (rotation position) of the rotating object 2 to be detected. The rotation detection device 3 includes a magnet 4 provided so as to rotate integrally with the body to be detected 2, and a sensor IC 6 provided on the substrate 5. The sensor IC 6 includes a magnetic sensor 7 that detects a magnetic field applied from the magnet 4. The magnet 4 has, for example, a disk shape and is arranged on the same axis as the detected body 2. The magnets 4 have magnetic poles arranged so that the north and south poles alternate along the circumferential direction. The object to be detected 2 is integrally rotatably inserted and fixed in the hole 8 of the annular magnet 4.

The magnetic sensor 7 is arranged outside the detected body 2 in the radial direction. In this way, the magnetic sensor 7 is arranged horizontally on the side of the magnet 4 (outer peripheral surface of the magnet 4), that is, horizontally with respect to the magnet 4. When the object to be detected 2 and the magnet 4 rotate around the axis L1, the direction of the magnetic field (direction of the magnetic field) applied from the magnet 4 to the magnetic sensor 7 changes. The magnetic sensor 7 detects a change in the magnetic field direction with respect to the magnetic field applied from the magnet 4, and outputs a detection signal Sa corresponding to the detected magnetic field direction.

As shown in FIG. 2, the magnetic sensor 7 includes a bridge pair 10 having a plurality of bridge circuits 11 in which magnetic resistance elements Rm are assembled in a full bridge shape. In the case of this example, the bridge pair 10 includes a total of two sets of bridge circuits 11 including a first bridge circuit 11a and a second bridge circuit 11b. The output of the first bridge circuit 11a and the second bridge circuit 11b each output a detection signal Sa whose output has a positive cosine relationship.

The reluctance elements Rm of the first bridge circuit 11a and the second bridge circuit 11b are formed in a shape in which the sensor elements 12 are alternately folded back, and are arranged at equal intervals in the circumferential direction along the element center P. It is arranged. The folded shape of the sensor element 12 is, for example, a zigzag shape in which the sensor pattern is alternately folded many times.

As shown in FIG. 3, in the first bridge circuit 11a, four elements of the first magnetic resistance element R1, the second magnetic resistance element R2, the third magnetic resistance element R3, and the fourth magnetic resistance element R4 are assembled in a full bridge shape. It is rare. In the second bridge circuit 11b, four elements of the fifth magnetic resistance element R5, the sixth magnetic resistance element R6, the seventh magnetic resistance element R7, and the eighth magnetic resistance element R8 are assembled in a full bridge shape. The first bridge circuit 11a and the second bridge circuit 11b are arranged so as to be out of phase by 45 degrees.

In the first bridge circuit 11a, the midpoint 14 of the first reluctance element R1 and the third reluctance element R3 is connected to the terminal 15 of the power supply Vcc, and the midpoint of the second reluctance element R2 and the fourth reluctance element R4 is connected. 16 is connected to the grounded terminal 17. The midpoint 18 of the first reluctance element R1 and the second reluctance element R2 is connected to the first plus side output terminal 19 that takes out the + side output of the magnetic field detection in the first bridge circuit 11a. The midpoint 20 of the third reluctance element R3 and the fourth reluctance element R4 is connected to the first negative side output terminal 21 that takes out the negative side output of the magnetic field detection in the first bridge circuit 11a. The first bridge circuit 11a outputs the potential difference between the first positive side output terminal 19 and the first negative side output terminal 21 as a detection signal Sa (in this example, the first detection signal Sa1) according to the detection magnetic field. ..

In the second bridge circuit 11b, the midpoint 24 of the fifth reluctance element R5 and the seventh reluctance element R7 is connected to the terminal 15 of the power supply Vcc, and the midpoint of the sixth reluctance element R6 and the eighth reluctance element R8. 25 is connected to the grounded terminal 17. The midpoint 26 of the fifth reluctance element R5 and the sixth reluctance element R6 is connected to the second plus side output terminal 27 that takes out the + side output of the magnetic field detection in the second bridge circuit 11b. The midpoint 28 of the sixth magnetoresistive element R6 and the seventh magnetic resistance element R7 is connected to the second negative side output terminal 29 that takes out the negative side output of the magnetic field detection in the second bridge circuit 11b. The second bridge circuit 11b outputs the potential difference between the second positive side output terminal 27 and the second negative side output terminal 29 as a detection signal Sa (in this example, the second detection signal Sa2) according to the detection magnetic field. ..

As shown in FIG. 5, the rotation detection device 3 includes an amplifier 35, a comparison unit 36, and a calculation unit 37. The amplifier 35 includes a first amplifier 35a that amplifies the first detection signal Sa1 output from the first bridge circuit 11a, and a second amplifier 35b that amplifies the second detection signal Sa2 output from the second bridge circuit 11b. Be prepared. The comparison unit 36 compares the amplification signal St output from the amplifier 35. The comparison unit 36 of this example is a first comparison unit 36a that compares the AC wave-shaped first amplification signal St1 output from the first amplifier 35a, and an AC wave-like second amplification signal output from the second amplifier 35b. It is provided with a second comparison unit 36b that compares St2.

As shown in FIG. 4, the first amplifier 35a generates, for example, a first amplification signal St1 that amplifies the first detection signal Sa1 of a sine wave. The second amplifier 35b generates, for example, a second amplification signal St2 that amplifies the second detection signal Sa2 of the cosine wave. The first amplified signal St1 and the second amplified signal St2 are generated as signals having a waveform having a positive cosine relationship. The first comparison unit 36a and the second comparison unit 36b output a rectangular wave pulse signal Sp as a signal after comparison. The first pulse signal Sp1 of the first comparison unit 36a and the second pulse signal Sp2 of the second comparison unit 36b are signals whose phases are out of phase by a predetermined amount (for example, 1/4 period).

As shown in FIG. 5, the calculation unit 37 detects the rotation (angle, rotation amount, rotation direction, etc.) of the object to be detected 2 based on the pulse signal Sp of the rectangular wave output from the comparison unit 36. The calculation unit 37 executes rotation detection of the detected body 2 based on the first pulse signal Sp1 input from the first comparison unit 36a and the second pulse signal Sp2 input from the second comparison unit 36b. As an example, for example, by counting the pulses of the square wave of the first pulse signal Sp1 and the second pulse signal Sp2, the angle of the object to be detected 2 can be calculated, or by the combination of the rise and fall of the pulse of the square wave. , The rotation direction of the detected object 2 is calculated.

The rotation detection device 3 has a function (normal operation monitoring function) of detecting whether or not the detected body 2 is not operating normally but is in a low-speed or stopped operating state. When the detected body 2 takes a rotating motion as in this example, the normal operation monitoring function detects whether or not the rotating state of the detected body 2 is low speed or stopped. In the case of this example, the responsiveness of the control related to the rotation calculation of the detected body 2 is improved by immediately determining the rotation state of the detected body 2.

In this case, the rotation detection device 3 includes a differential processing unit 41, an absolute value conversion unit 42, a signal processing unit 43, and a determination unit 44. The differential processing unit 41 includes a first differential processing unit 41a on the first bridge circuit 11a side and a second differential processing unit 41b on the second bridge circuit 11b side. The absolute value conversion unit 42 includes a first absolute value conversion unit 42a on the first bridge circuit 11a side and a second absolute value conversion unit 42b on the second bridge circuit 11b side.

The differentiation processing unit 41 inputs the first detection signal Sa1 and the second detection signal Sa2 having a positive cosine relationship from the bridge pair 10, and differentiates them respectively. In the case of this example, the differentiation processing unit 41 differentiates the first detection signal Sa1 and the second detection signal Sa2, that is, the amplification signals St (first amplification signal St1, second amplification signal St2) input via the amplifier 35. Specifically, the first amplification signal St1 is differentiated by the first differential processing unit 41a to generate the first differential signal Sr1, and the second amplification signal St2 is differentiated by the second differential processing unit 41b to generate the second differential signal. Sr2 is generated.

The absolute value conversion unit 42 converts the first differential signal Sr1 and the second differential signal Sr2 into absolute values, respectively. In the case of this example, the absolute value conversion unit 42 full-wave rectifies the first differential signal Sr1 and the second differential signal Sr2 as absolute value conversion. Further, in this example, the first differential signal Sr1 is subjected to absolute value conversion by the first absolute value conversion unit 42a to generate the first conversion signal Sv1, and the second differential signal Sr2 is absolutely converted by the second absolute value conversion unit 42b. The value is converted and the second conversion signal Sv2 is generated.

Based on the first conversion signal Sv1 and the second conversion signal Sv2, the signal processing unit 43 generates and outputs a control signal Srot capable of determining the operating state of the low speed or stop of the detected object 2. In the case of this example, the signal processing unit 43 includes a comparison unit 46 and a signal generation unit 47. The comparison unit 46 compares the first conversion signal Sv1 and the second conversion signal Sv2, respectively. The comparison unit 46 of this example includes a first comparison unit 46a that compares the first conversion signal Sv1 and a second comparison unit 46b that compares the second conversion signal Sv2.

The signal generation unit 47 combines the first conversion signal Sv1 with the comparison unit 46 (first comparison unit 46a) to obtain the first rectangular wave Sw1 and the second conversion signal Sv2 with the comparison unit 46 (second comparison unit 46a). The control signal Srot is generated based on the second rectangular wave Sw2 obtained by comparing with 46b). For example, when both the first conversion signal Sv1 and the second conversion signal Sv2 are less than the threshold value Sk, the control signal Srot preferably takes a signal waveform in which Hi / Lo is inverted.

The determination unit 44 determines whether or not the detected body 2 is in a low speed or stop operating state based on the control signal Srot generated by the signal processing unit 43. The determination unit 44 determines whether or not the detected body 2 is in a low speed or stopped operating state based on the Hi / Lo switching of the control signal Srot. For example, when the control signal Srot takes a Hi level during normal operation, when the determination unit 44 detects that the control signal Srot has reached the Lo level, it determines that the detected body 2 is in a low speed or stop operating state. do.

Next, the operation of the position detection device 1 of the present embodiment will be described with reference to FIG.
As shown in FIG. 6, since the first differential signal Sr1 and the second differential signal Sr2 are signals obtained by differentiating the amplified signal St, they are output as signal waveforms corresponding to the momentary change amount of the amplified signal St. The first conversion signal Sv1 is output as a signal obtained by full-wave rectifying the first differential signal Sr1. Further, the second conversion signal Sv2 is output as a signal obtained by full-wave rectifying the second differential signal Sr2. The first square wave Sw1 is output as a signal that takes the Hi level when the threshold value Sk or more and takes the Lo level when the threshold value Sk is less than the threshold value Sk in the first conversion signal Sv1. Further, the second square wave Sw2 is output as a signal that takes the Hi level when the threshold value Sk or more and takes the Lo level when the threshold value Sk is less than the threshold value Sk in the second conversion signal Sv2.

The signal generation unit 47 generates the control signal Srot by, for example, ORing the first square wave Sw1 and the second square wave Sw2. In this case, the signal generation unit 47 is composed of an OR circuit. As described above, the control signal Srot of this example is output as a signal obtained by ORing the Hi / Lo of the first square wave Sw1 and the Hi / Lo of the second square wave Sw2. Therefore, when both the first square wave Sw1 and the second square wave Sw2 are at the Lo level, the Lo level control signal Srot is output, and when at least one of the first square wave Sw1 and the second square wave Sw2 is at the Hi level. , Hi level control signal Srot is output.

Here, at the time t1 shown in FIG. 6, for example, it is assumed that the rotation of the detected body 2 is in a low speed or stopped state. The cause of the low speed or stop of the rotation of the detected body 2 is, for example, an external load applied to the rotation of the detected body 2 or a malfunction of the detected body 2 or its peripheral parts.

When the rotation of the object to be detected 2 is slow or stopped, the waveform changes of the first amplification signal St1 and the second amplification signal St2 (first detection signal Sa1 and second detection signal Sa2) are the same as in the normal state. Do not take. For example, when the detected body 2 is stopped, the first amplified signal St1 and the second amplified signal St2 do not change and are maintained at constant values. Further, when the speed of the detected body 2 becomes low, the slope of change of the first amplified signal St1 and the second amplified signal St2 becomes smaller.

Therefore, when the rotation of the object to be detected 2 is slow or stopped, the values of the first differential signal Sr1 (first conversion signal Sa1) and the second differential signal Sr2 (second conversion signal Sa2) remain constant. Take a signal waveform that does not change. As a result, both the first conversion signal Sv1 and the second conversion signal Sv2 become less than the threshold value Sk, and as a result, both the first square wave Sw1 and the second square wave Sw2 are switched to the Lo level. At this time, the control signal Srot switches from the Hi level up to that point to the Lo level, and the detected object 2 is output in the Lo level state during low speed or stop.

The determination unit 44 constantly monitors the signal level of the control signal Srot, and when it detects that the control signal Srot has reached the Lo level, it determines that the detected body 2 has taken a low speed or stopped state. Then, the determination unit 44 outputs a non-normal state notification to the effect that the rotation state of the detected body 2 is not normal, for example, to the calculation unit 37 or another ECU. Therefore, when the calculation unit 37 and other ECUs input the abnormal state notification from the determination unit 44, they take various measures such as stopping the calculation or stopping the rotation of the detected body 2. ..

By the way, when the detected body 2 takes a normal rotation state, the first square wave Sw1 and the second square wave Sw2 take a Lo level signal state. However, when the detected body 2 is rotating normally, even if the first square wave Sw1 becomes the Lo level, the second square wave Sw2 takes the Hi level at that timing, so that the control signal Srot is at the Hi level. It is output. This also applies when the Hi / Lo of the first square wave Sw1 and the second square wave Sw2 are opposite. Therefore, when the detected body 2 rotates normally, the determination unit 44 can input the Hi level control signal Srot and recognize that the detected body 2 rotates normally.

According to the position detection device 1 of the above embodiment, the following effects can be obtained.
(1) The position detection device 1 is provided with a bridge pair 10 having two bridge circuits 11 in which the reluctance elements Rm are assembled in a bridge shape, and is output from the bridge circuit 11 as a waveform having a positive cosine relationship. Based on the signal Sa, the position of the object to be detected 2 that moves integrally with the magnet 4 that applies a magnetic field to the magnetoresistive element Rm is detected. The position detection device 1 includes a differentiation processing unit 41, a signal processing unit 43, and a determination unit 44. The differentiation processing unit 41 inputs the first detection signal Sa1 and the second detection signal Sa2 having a positive cosine relationship from the bridge pair 10, and differentiates them respectively. The signal processing unit 43 of the detected object 2 is based on the first differential signal Sr1 obtained by differentiating the first detection signal Sa1 and the second differential signal Sr2 obtained by differentiating the second detection signal Sa2. A control signal Srot that can determine the operating state of low speed or stop is generated and output. The determination unit 44 determines whether or not the detected body 2 is in a low speed or stopped operating state based on the control signal Srot generated by the signal processing unit 43.

According to the configuration of this example, the first differential signal Sr1 and the second differential signal Sr2 are signals obtained by differentiating the output of the bridge pair 10 (bridge circuit 11). Therefore, when the detected body 2 is in the operating state of low speed or stop, the change in the operating state immediately appears in the first differential signal Sr1 and the second differential signal Sr2. Therefore, if the operating state of the detected body 2 is determined based on the control signal Srot generated from the first differential signal Sr1 and the second differential signal Sr2, when the detected body 2 slows down or stops. These states can be immediately determined from the control signal Srot. Therefore, the operating state of the detected body 2 can be quickly determined without changing the number of magnetic poles of the magnet 4. As a result, the responsiveness of the control can be improved.

(2) The absolute value conversion unit 42 converts the first differential signal Sr1 and the second differential signal Sr2 into absolute values, respectively. The signal processing unit 43 controls based on the first conversion signal Sv1 obtained by converting the first differential signal Sr1 to an absolute value and the second conversion signal Sv2 obtained by converting the second differential signal Sr2 to an absolute value. Generates and outputs the signal Srot. In this case, the rotation state is not determined by using the first differential signal Sr1 and the second differential signal Sr2 as they are, but the state is determined from the values obtained by converting the first differential signal Sr1 and the second differential signal Sr2 into absolute values. , The rotation state can be determined by simple signal processing.

(3) The absolute value conversion unit 42 generates the first conversion signal Sv1 and the second conversion signal Sv2 by full-wave rectifying the first differential signal Sr1 and the second differential signal Sr2, respectively. In this case, the low speed or stop operating state of the detected body 2 is determined from the first conversion signal Sv1 and the second conversion signal Sv2 generated by full-wave rectification of the first differential signal Sr1 and the second differential signal Sr2, respectively. can do.

(4) The signal processing unit 43 includes a comparison unit 46 and a signal generation unit 47. The comparison unit 46 compares the first conversion signal and the second conversion signal, respectively. The signal generation unit 47 is based on the first square wave Sw1 obtained by comparing the first conversion signal Sv1 and the second square wave Sw2 obtained by comparing the second conversion signal Sv2, and the control signal Srot. To generate. According to this configuration, when the detected body 2 becomes low speed or stopped, for example, the first rectangular wave Sw1 and the second rectangular wave Sw2 become Lo level together with the detected body 2. Therefore, the detected body 2 is detected by detecting this level state. Can be determined to be in a low speed or stop operating state. On the other hand, when the operating state of the detected object 2 is normal, for example, even if the first square wave Sw1 reaches the Lo level, the second square wave Sw2 takes the Hi level and the second square wave Sw2 becomes the Lo level. However, since the first square wave Sw1 takes the Hi level, the control signal Srot does not show an abnormality. Therefore, the operating state at this time is not determined to be low speed or stopped.

(5) When both the first conversion signal Sv1 and the second conversion signal Sv2 are less than the threshold value Sk, the signal processing unit 43 outputs a control signal Srot in which Hi / Lo is inverted. The determination unit 44 determines whether or not the detected body 2 is in a low speed or stopped operating state based on the Hi / Lo switching of the control signal Srot. Therefore, the operating state of the detected body 2 can be quickly determined by a simple method of confirming the Hi / Lo level of the control signal Srot.

(6) The magnet 4 is formed in an annular shape so as to rotate on the same axis as the body 2 to be detected, and the magnetic poles of the N pole and the S pole are arranged alternately in the circumferential direction. The magnetic sensor 7 provided with the bridge pair 10 is arranged laterally on the magnet 4 along the radial direction of the magnet 4. Therefore, the magnetic field from the magnet 4 can be applied to the magnetic sensor 7 in a suitable direction, which contributes to ensuring the accuracy of position detection.

In addition, this embodiment can be implemented by changing as follows. The present embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
-As shown in FIG. 7, another bridge pair 51 is provided separately from the bridge pair 10 used for position calculation, and is detected based on the signals (sine wave signal, cosine wave signal) input from the other bridge pair 51. The determination of the low speed or stop operating state of the body 2 may be performed. In the case of the example of the figure, the other bridge pair 51 includes a third bridge circuit 52a that outputs a sine wave according to the direction of the detected magnetic field and a fourth bridge circuit 52b that outputs a cosine wave according to the direction of the detected magnetic field. To be equipped. The signal of the third bridge circuit 52a is input to the first differential processing unit 41a via the amplifier 53a. The signal of the fourth bridge circuit 52b is input to the second differential processing unit 41b via the amplifier 53b. Since the subsequent operations are the same as the operation examples described in the embodiment, the description thereof will be omitted.

-The bridge circuit 11 is not limited to a full bridge, but may be a half bridge.
The period of the detection signal Sa is not limited to 180 degrees, and may be, for example, 360 degrees.
The phase difference between the first detection signal Sa1 and the second detection signal Sa2 may be changed to a value other than 45 degrees.

The first detection signal Sa1 may be a cosine wave signal, and the second detection signal Sa2 may be a sine wave signal.
-The first detection signal Sa1 is not limited to the sine wave signal, and may be a signal having a waveform other than this. Further, the second detection signal Sa2 is not limited to the cosine wave signal, and may be a signal having a waveform other than this.

The absolute value conversion unit 42 is not limited to the full-wave rectifier unit (full-wave rectifier circuit), and other circuits may be used.
The absolute value conversion unit 42 may be omitted from the components of the position detection device 1.

The signal processing unit 43 is not limited to being constructed from the comparison unit 46 and the signal generation unit 47, and may be a circuit capable of converting the first conversion signal Sv1 and the second conversion signal Sv2 into a control signal Srot having a predetermined waveform. Just do it.

The signal generation unit 47 is not limited to the OR circuit, and various logic circuits can be applied.
As shown in FIGS. 8 to 10, the sensor IC 6 (magnetic sensor 7) is not limited to being arranged horizontally with respect to the magnet 4, and is arranged vertically, for example, arranged side by side in the axial direction of the object to be detected 2. May be. In this case, the magnet 4 preferably has a structure magnetized in the thickness direction. Further, the sensor IC 6 (magnetic sensor 7) may be arranged offset radially outward of the magnet 4 with respect to the pole of the magnet 4.

The position detection device 1 is not limited to the device for detecting rotation (rotation detection device 3), and may be, for example, a device for linear detection in which the object to be detected 2 moves in a linear direction.

1 ... position detection device, 2 ... detected object, 3 ... rotation detection device, 4 ... magnet, 7 ... magnetic sensor, 10 ... bridge pair, 11 ... bridge circuit, 11a ... first bridge circuit, 11b ... second bridge circuit , 41 ... Differential processing unit, 42 ... Absolute value conversion unit, 43 ... Signal processing unit, 44 ... Judgment unit, 46 ... Comparison unit, 47 ... Signal generation unit, 51 ... Other bridge pair, 52a ... Third bridge circuit, 52b ... 4th bridge circuit, Rm ... Magnetic resistance element, Sa ... Detection signal, Sa1 ... 1st detection signal, Sa2 ... 2nd detection signal, Sa3 ... 3rd detection signal, Sa4 ... 4th detection signal, Sr1 ... 1st differentiation Signal, Sr2 ... 2nd differential signal, Sv1 ... 1st conversion signal, Sv2 ... 2nd conversion signal, Sw1 ... 1st rectangular wave, Sw2 ... 2nd rectangular wave, Srot ... control signal, Sk ... threshold, L1 ... axis.

Claims (6)

A bridge pair having two bridge circuits in which the reluctance elements are assembled in a bridge shape is provided, and a magnetic field is applied to the reluctance element based on a detection signal output from the bridge circuit in a waveform having a positive cosine relationship. It is a rotation detection device that detects the position of the object to be detected that moves integrally with the magnet to be applied.
A differentiation processing unit that inputs a first detection signal and a second detection signal having a positive cosine relationship from the bridge pair or another bridge pair that forms a pair with the bridge pair and differentiates them, respectively.
Based on the first differential signal obtained by differentiating the first detection signal and the second differential signal obtained by differentiating the second detection signal, the low speed or stop operating state of the detected object is determined. A signal processing unit that generates and outputs possible control signals,
A position detection device including a determination unit for determining whether or not the object to be detected is in a low speed or stop operating state based on the control signal generated by the signal processing unit. An absolute value conversion unit that converts the first differential signal and the second differential signal into absolute values is provided.
The signal processing unit uses the control signal based on the first conversion signal obtained by converting the first differential signal into an absolute value and the second conversion signal obtained by converting the second differential signal into an absolute value. The position detection device according to claim 1, wherein the position detection device is generated and output. The position detection device according to claim 2, wherein the absolute value conversion unit generates the first conversion signal and the second conversion signal by full-wave rectifying the first differential signal and the second differential signal, respectively. .. The signal processing unit
A comparison unit that compares the first conversion signal and the second conversion signal, respectively.
A signal generation unit that generates the control signal based on the first square wave obtained by comparing the first conversion signal and the second square wave obtained by comparing the second conversion signal. The position detecting device according to claim 2 or 3. When both the first conversion signal and the second conversion signal are less than the threshold value, the signal processing unit outputs the control signal in which Hi / Lo is inverted.
The position detection device according to claim 4, wherein the determination unit determines whether or not the object to be detected is in an operating state of low speed or stop based on the switching of Hi / Lo of the control signal. The magnet is formed in an annular shape so as to rotate on the same axis as the object to be detected, and the magnetic poles of the north and south poles are alternately arranged and arranged in the circumferential direction.
The position detecting device according to any one of claims 1 to 5, wherein the magnetic sensor including the bridge pair is laterally arranged on the magnet along the radial direction of the magnet.

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