JP2023013138A - Position detection device - Google Patents

Abstract

To provide a position detection device capable of downsizing a device size.SOLUTION: A position detection device 1 includes a bridge circuit 4 obtained by assembling a plurality of magnetoresistive elements 7 for detecting a magnet 3 interlocked with a movable body 2 in a bridge shape. The position detection device 1 obtains a difference between a first detection signal V1 detected from an intermediate point 14 of a first element pair 8 of the bridge circuit 4 and a second detection signal V2 detected from an intermediate point 15 of a second element pair 9 of the bridge circuit 4 to detect a position of the movable body 2. In the bridge circuit 4, at least one resistance value R of the plurality of magnetoresistive elements 7 is set to a value different from a resistance value R of the other magnetoresistive elements 7.SELECTED DRAWING: Figure 1

Description

The present invention relates to a position detection device that detects a position based on the output of a bridge circuit of magnetoresistive elements.

2. Description of the Related Art Conventionally, a position detection device that detects the position of a movable body using a magnetic sensor in which four magnetoresistive elements are arranged in a bridge shape is well known (see, for example, Patent Document 1). In this type of position detection device, a magnet is attached to the movable body, and the magnetic field applied from the magnet to the magnetic sensor changes according to the position of the movable body. A change in the magnetic field at this time is detected by a magnetic sensor to determine the position of the movable body.

JP-A-2002-81903

By the way, in this type of position detection device, there is a great need for miniaturization of the device, so some countermeasures for device size have been required.

A position detecting device for solving the above-mentioned problems is provided with a bridge circuit by assembling a plurality of magnetoresistive elements that detect a magnet interlocking with a movable body in a bridge form, and detects from an intermediate point of a first element pair of the bridge circuit. and a second detection signal detected from an intermediate point of the second element pair of the bridge circuit to detect the position of the movable body. A resistance value of at least one of the magnetoresistive elements is set to a value different from the resistance values of the other magnetoresistive elements.

According to the present invention, the device size can be reduced.

1 is a configuration diagram of a position detection device according to an embodiment; FIG. FIG. 4 is an explanatory diagram showing the positional relationship between the magnet and the bridge circuit at the movement start position; Explanatory drawing which shows the change of the magnetic field applied to a bridge circuit from a magnet. FIG. 5 is an explanatory diagram showing the positional relationship between the magnet and the bridge circuit at the movement end position; Waveform diagrams of a first detection signal and a second detection signal. Waveform diagrams of a first detection signal and a second detection signal in a conventional position detection device for positioning. Schematic diagram for explaining size reduction of a magnet.

An embodiment of the present disclosure will be described below.
As shown in FIG. 1 , the position detection device 1 includes a magnet 3 provided on a movable body 2 and a bridge circuit 4 for detecting the magnetic field E of the magnet 3 . The position detection device 1 is of a magnetic type that detects the position of the movable body 2 by detecting the magnetic field E of the magnet 3 interlocking with the movable body 2 with the bridge circuit 4 . The position detection device 1 is used, for example, for position detection of a switch device. The movable body 2 detects the position of the movable body 2 that is moved by a user's operation when used in a switch device.

The magnet 3 is arranged in a direction in which the magnetic pole direction (NS direction) intersects the moving direction of the movable body 2 (the direction of the white arrow in the figure). The magnet 3 linearly reciprocates along with the movable body 2 on the side of the bridge circuit 4 .

The bridge circuit 4 has a plurality of magnetoresistive elements 7 assembled in a bridge shape. In this example, the bridge circuit 4 has four magnetoresistive elements 7 . The bridge circuit 4 includes a first element pair 8 in which a first magnetoresistive element 7a and a second magnetoresistive element 7b are connected in series, and a second magnetoresistive element in which a third magnetoresistive element 7c and a fourth magnetoresistive element 7d are connected in series. and an element pair 9 . Each of the first element pair 8 and the second element pair 9 is a half bridge circuit in which two magnetoresistive elements 7 are connected in series.

The bridge circuit 4 consists of a circuit in which a first element pair 8 and a second element pair 9 are connected in parallel. Thus, the bridge circuit 4 is a circuit in which two half bridge circuits are connected in parallel. In this example, the resistance value R of the first magnetoresistive element 7a is "R1", the resistance value R of the second magnetoresistive element 7b is "R2", and the resistance value R of the third magnetoresistive element 7c is "R3" and the resistance value R of the fourth magnetoresistive element 7d is "R4". The bridge circuit 4 detects the magnetic field E of the magnet 3 using the plane in the direction in which the magnetoresistive elements 7 are arranged as a detection plane.

The first magnetoresistive element 7a has one end connected to a terminal 12 connected to a power supply Vc and the other end connected to the second magnetoresistive element 7b. The second magnetoresistive element 7b has one end connected to the first magnetoresistive element 7a and the other end connected to a terminal 13 connected to the ground. The third magnetoresistive element 7c has one end connected to a terminal 13 connected to the ground, and the other end connected to the fourth magnetoresistive element 7d. The fourth magnetoresistive element 7d has one end connected to the third magnetoresistive element 7c and the other end connected to a terminal 12 connected to the power supply Vc.

The bridge circuit 4 outputs the first detection signal V1 from the intermediate point 14 of the first element pair 8 (the first magnetoresistive element 7a and the second magnetoresistive element 7b), and the second element pair 9 (the third magnetoresistive element A second detection signal V2 is output from an intermediate point 15 between the element 7c and the fourth magnetoresistive element 7d). The first detection signal V1 is an intermediate potential between the first magnetoresistive element 7a and the second magnetoresistive element 7b. The second detection signal V2 is an intermediate potential between the third magnetoresistive element 7c and the fourth magnetoresistive element 7d.

At least one of the magnetoresistive elements 7 has a resistance value R set to a value different from the resistance values R of the other magnetoresistive elements 7 . In this example, the magnetoresistive elements 7 are set so that the resistance values R are different in the same element pair. Specifically, the resistance value R is made different between the first magnetoresistive element 7a and the second magnetoresistive element 7b of the first element pair 8, and the third magnetoresistive element 7c and the fourth magnetoresistive element 7c of the second element pair 9 The resistance value R is made different from that of the element 7d.

In this way, the resistance values R are set by shifting in the same element pair when the magnetic field E from the magnet 3 is not applied to the bridge circuit 4, or when the applied magnetic field E is weak. , the difference between the first detection signal V1 and the second detection signal V2 is increased. In this way, even if the bridge circuit 4 is affected by disturbance when the magnet 3 is positioned at the movement start position or the movement end position and is positioned away from the bridge circuit 4, the output from the bridge circuit 4 will be Therefore, a situation in which the magnitudes of the first detection signal V1 and the second detection signal V2 are reversed is less likely to occur. Therefore, it is difficult for the magnitude relationship between the first detection signal V1 and the second detection signal V2 to become unstable.

In the case of this example, among the first magnetoresistive element 7a, the second magnetoresistive element 7b, the third magnetoresistive element 7c, and the fourth magnetoresistive element 7d, each of the groups of the magnetoresistive elements 7 facing the bridge is A first element group 17 and a second element group 18 are used. In this example, the first element group 17 includes a first magnetoresistive element 7a and a third magnetoresistive element 7c. The second element group 18 includes a second magnetoresistive element 7b and a fourth magnetoresistive element 7d.

The resistance value R of each magnetoresistive element 7 of the first element group 17 is set higher than the resistance value R of each magnetoresistive element 7 of the second element group 18 . Specifically, the resistance value R1 of the first magnetoresistive element 7a is set higher than the resistance value R2 of the second magnetoresistive element 7b (relationship R1>R2). The resistance value R3 of the third magnetoresistive element 7c is set higher than the resistance value R4 of the fourth magnetoresistive element 7d (relationship R3>R4). In this example, the resistance value R1 of the first magneto-resistive element 7a and the resistance value R3 of the third magneto-resistive element 7c are set to the same value (relationship of R1=R3). The resistance value R2 of the second magnetoresistive element 7b and the resistance value R4 of the fourth magnetoresistive element 7d are set to the same value (relationship of R2=R4).

The position detection device 1 includes a comparator 20 that obtains the difference between the first detection signal V1 and the second detection signal V2 that are input from the bridge circuit 4 . The comparator 20 has a first input terminal 21 connected to the midpoint 14 of the first element pair 8 and a second input terminal 22 connected to the midpoint 15 of the second element pair 9 . The comparator 20 outputs the difference between the first detection signal V1 and the second detection signal V2 to the lower stage as the difference signal Sa.

The position detection device 1 includes a logic circuit 23 and a position determination section 24 . The logic circuit 23 has an input connected to the comparator 20 and an output connected to the position determination section 24 . The logic circuit 23 outputs the binary code Sb to the position determination section 24 based on the difference signal Sa input from the comparator 20, that is, the difference between the first detection signal V1 and the second detection signal V2. The binary code Sb is either a Hi signal or a Lo signal.

The position determination unit 24 determines the position of the movable body 2 based on the binary code Sb input from the logic circuit 23 . For example, when the Lo signal is input as the binary code Sb, the position determination unit 24 determines that the switch detection is "off". On the other hand, the position determination unit 24 determines that the switch detection is "ON" when a Hi signal is input as the binary code Sb, for example. In this way, the position determination unit 24 detects the position of the movable body 2 and determines whether switch detection is on or off.

Next, the operation of the position detection device 1 of this embodiment will be described.
As shown in FIG. 2, when the movable body 2 is not operated, the magnet 3 is positioned at the movement start position (time "t0"). The movement start position is the initial position before the movable body 2 is operated. At this time, the magnet 3 is positioned far away from the bridge circuit 4 . At this time, the sensing surface of the bridge circuit 4 from the magnet 3 is in a state where no magnetic field E is applied or a weak magnetic field E is applied.

As shown in FIG. 3, when the movable body 2 is operated, the magnet 3 also moves linearly so as to approach the bridge circuit 4 in accordance with the movement of the movable body 2, and after passing the magnet 3, Come away. At this time, the magnetic field E applied from the magnet 3 to the bridge circuit 4 changes with respect to the detection surface of the bridge circuit 4 while changing its direction in the clockwise direction on the paper surface.

Specifically, when the magnet 3 is positioned diagonally to the upper left of the bridge circuit 4 (at time t1), the bridge circuit 4 is provided with a magnetic field E oriented diagonally downward to the right of the paper at 45 degrees. . When the magnet 3 is positioned directly above the bridge circuit 4 on the page (at time "t2"), the bridge circuit 4 is provided with a magnetic field E oriented downward on the page. When the magnet 3 is positioned diagonally to the upper right of the bridge circuit 4 on the page (time "t3"), the bridge circuit 4 is provided with a magnetic field E oriented diagonally to the lower left of the page at 45 degrees. When the magnet 3 is positioned diagonally to the upper right of the bridge circuit 4 on the paper surface (at time "t4"), the bridge circuit 4 is provided with a magnetic field E directed leftward on the paper surface.

As shown in FIG. 4 , when the movable body 2 reaches the movement end position (time “t5”), the magnet 3 is positioned far away from the bridge circuit 4 . At this time, the sensing surface of the bridge circuit 4 from the magnet 3 is in a state where no magnetic field E is applied or a weak magnetic field E is applied.

FIG. 5 shows output waveforms of the first detection signal V1 and the second detection signal V2 when the magnet 3 moves with respect to the bridge circuit 4. As shown in FIG. In the case of this example, the resistance value R1 of the first magneto-resistive element 7a and the resistance value R3 of the third magneto-resistive element 7c are replaced by the resistance value R2 of the second magneto-resistive element 7b and the resistance value R4 of the fourth magneto-resistive element 7d. and are set in a staggered manner. Therefore, at time "t0", under the condition that the magnetic field E is not applied from the magnet 3 to the bridge circuit 4, or under the condition that the weak magnetic field E is applied, between the first detection signal V1 and the second detection signal V2, , a voltage difference corresponding to the shift amount of the resistance value R is generated. Therefore, since there is a sufficient voltage difference between the first detection signal V1 and the second detection signal V2, it is difficult for the detection state to become unstable.

When the difference between the first detection signal V1 and the second detection signal V2 is less than the threshold, the logic circuit 23 outputs a Lo signal to the position determination section 24 as a binary code Sb. Therefore, the position determination unit 24 determines the switch state as "off" by inputting the Lo signal from the logic circuit 23 .

In the case of this example, the first detection signal V1 has an AC waveform whose value changes in the order of decrease→rise→decrease when the magnet 3 moves from the movement start position toward the position end position. On the other hand, the second detection signal V2 has an AC waveform whose value changes in the order of increasing→decreasing→increasing when the magnet 3 moves from the movement start position toward the movement end position. Specifically, the value of the first detection signal V1 gradually decreases when the magnet 3 begins to move from the movement start position and approaches the bridge circuit 4, increases from around time t1, and returns to V1. Take down waveform change. On the other hand, the value of the second detection signal V2 gradually increases when the magnet 3 starts to move from the movement start position and approaches the bridge circuit 4, then decreases from around time t1, and the value changes again. take.

After the movable body 2 moves from the movement start position, the difference between the first detection signal V1 and the second detection signal V2 is less than the threshold for a while. Therefore, the logic circuit 23 continues to output the Lo signal. Therefore, the determination that the switch state is "off" is continued between times "t0" and "t2".

Around time t2, the difference between the first detection signal V1 and the second detection signal V2 becomes equal to or greater than the threshold. Therefore, the logic circuit 23 outputs a Hi signal to the position determination section 24 as the binary code Sb. Therefore, the position determination unit 24 determines that the switch state is "on" by inputting the Hi signal from the logic circuit 23 .

Around time t4, the difference between the first detection signal V1 and the second detection signal V2 again changes to less than the threshold. Therefore, the logic circuit 23 outputs the Lo signal to the position determination section 24 as the binary code Sb. Therefore, the position determination unit 24 determines the switch state as "OFF" by inputting the Lo signal.

Here, a conventional positioning position detection device 1 will be described with reference to FIG. In the conventional positioning position detection device 1, it is assumed that the resistance values R of the first to fourth magnetoresistive elements 7a to 7d are all the same. In this configuration, when the magnetic field E is not applied from the magnet 3 to the bridge circuit 4 or the magnetic field E applied to the bridge circuit 4 is weak, both the first detection signal V1 and the second detection signal V2 are at the reference potential. take. The reference potential is the voltage value when the bridge circuit 4 is not affected by the magnetic field E of the magnet 3 .

In the case of the conventional position detection device 1, when the magnetic field E is not applied from the magnet 3 to the bridge circuit 4 or the magnetic field E applied to the bridge circuit 4 is weak, the first detection signal V1 and the second detection signal V2 take approximately the same value. Therefore, when the bridge circuit 4 receives disturbance, depending on the situation, the magnitude relationship between the first detection signal V1 and the second detection signal V2 may be reversed. V2 becomes unstable.

Therefore, the output of the bridge circuit 4 cannot be used for position determination in the section where the magnetic field E of the magnet 3 does not reach or hardly reaches the bridge circuit 4 within the stroke range of the magnet 3 . For this reason, when the position is determined from the output of the bridge circuit 4, a situation must be established in which the magnetic field E of a certain strength is applied from the magnet 3 to the bridge circuit 4. FIG. Therefore, the size of the magnet 3 must be increased.

On the other hand, as shown in FIG. 7, in this example, when the magnetic field E is not applied from the magnet 3 to the bridge circuit 4 or the magnetic field E applied to the bridge circuit 4 is weak, the first detection signal V1 and Since a large difference occurs in the second detection signal V2, it is difficult for the first detection signal V1 and the second detection signal V2 to become unstable. As a result, even a section in which the magnetic field E of the magnet 3 does not reach the bridge circuit 4 can be used as a section for position determination. Therefore, it becomes possible to reduce the size of the magnet 3 . As a result, the device size of the position detection device 1 can also be reduced.

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 circuit 4 by assembling a plurality of magnetoresistive elements 7 for detecting the magnet 3 interlocking with the movable body 2 in a bridge shape. The position detection device 1 detects a first detection signal V1 detected from the midpoint 14 of the first element pair 8 of the bridge circuit 4 and a second detection signal V1 detected from the midpoint 15 of the second element pair 9 of the bridge circuit 4. The position of the movable body 2 is detected by obtaining the difference from the signal V2. In the position detection device 1 , the resistance value R of at least one of the plurality of magnetoresistive elements 7 is set to a value different from the resistance values R of the other magnetoresistive elements 7 .

According to the configuration of this example, as the movable body 2 moves, the magnet 3 is positioned away from the bridge circuit 4, and the magnetic field E of the magnet 3 is not applied to the bridge circuit 4, or the weak magnetic field E Even in such a state, it is possible to generate a certain amount of difference between the first detection signal V1 and the second detection signal V2. Therefore, the magnitude relationship of the first detection signal V1 and the second detection signal V2 is stabilized when the magnet 3 is positioned away from the bridge circuit 4, so that this position is also within the range of the position determination of the movable body 2. It becomes possible to As a result, there is no need to employ a configuration in which the magnetic field E of the magnet 3 is constantly applied to the bridge circuit 4 over the entire range of movement of the movable body 2, so the size of the magnet 3 can be reduced accordingly. Therefore, the device size of the position detection device 1 can be reduced.

(2) In the position detection device 1, the magnetoresistive elements 7 of the first element pair 8 have different resistance values R, and the magnetoresistive elements 7 of the second element pair 9 have different resistance values R. According to this configuration, the resistance value R of each magnetoresistive element 7 can be set to an optimum value.

(3) The first element pair 8 has a first magnetoresistive element 7a connected to a terminal 12 connected to the power supply Vc and a second magnetoresistive element 7b connected to a terminal 13 connected to the ground. The second element pair 9 has a third magnetoresistive element 7c connected to a terminal 13 connected to the ground, and a fourth magnetoresistive element 7d connected to a terminal 12 connected to the power supply Vc. Of the first magnetoresistive element 7a, the second magnetoresistive element 7b, the third magnetoresistive element 7c, and the fourth magnetoresistive element 7d, each of the groups of the magnetoresistive elements 7 facing the bridge is arranged in the first element group 17 and the When the second element group 18 is used, the resistance value R (R1 and R3) are the resistance values R (R2 and R4 in this example) of the magnetoresistive elements 7 (second magnetoresistive element 7b and fourth magnetoresistive element 7d in this example) of the second element group 18. is set too high.

According to this configuration, the waveforms of the first detection signal V1 and the second detection signal V2 can be changed such that when one increases, the other decreases, and when the other decreases, the other increases. It becomes possible. Therefore, the waveforms of the first detection signal V1 and the second detection signal V2 can be made to have regularity, which contributes to simplification of the position determination process.

(4) The same resistance value R is set for the first magnetoresistive element 7a and the third magnetoresistive element 7c. The same resistance value R is set for the second magnetoresistive element 7b and the fourth magnetoresistive element 7d. According to this configuration, it is possible to make the waveforms of the first detection signal V1 and the second detection signal V2 have regularity in relation to each other. This further contributes to simplification of position determination processing.

(5) When the movable body 2 is in at least one of the movement start position and the movement end position, the magnet 3 is in a state where the bridge circuit is not subjected to the magnetic field E or a weak magnetic field E is applied to the bridge circuit. It is arranged so that it is in a state where According to this configuration, at least one of the movement start position and the movement end position of the movable body 2 can be used for position determination. Therefore, it is not necessary to set the size of the magnet 3 so that the magnetic field E is always applied to the bridge circuit 4 . Therefore, the size of the magnet 3 can be reduced accordingly.

(6) The logic circuit 23 of the position detection device 1 outputs a binary code Sb based on the difference between the first detection signal V1 and the second detection signal V2. A position determination unit 24 included in the position detection device 1 determines the position of the movable body 2 based on the binary code Sb input from the logic circuit 23 . According to this configuration, the binary code Sb based on the difference between the first detection signal V1 and the second detection signal V2 is output from the logic circuit 23 to the position determination section 24, and the position of the movable body 2 is transmitted to the position determination section 24. It is possible to judge. Therefore, the position detection device 1 can be provided with the logic circuit 23 and the position determination section 24 that execute such processing.

In addition, this embodiment can be changed and implemented as follows. This embodiment and the following modified examples can be implemented in combination with each other within a technically consistent range.
- The resistance value R2 of the second magnetoresistive element 7b is higher than the resistance value R1 of the first magnetoresistive element 7a, and the resistance value R4 of the fourth magnetoresistive element 7d is higher than the resistance value R3 of the third magnetoresistive element 7c. You can make it higher.

- The resistance values R of the magneto-resistive elements 7 may be combined in any combination as long as they are not all the same value.
- The magnet 3 is not limited to a magnetic pole pattern in which one side in the planar direction is the N pole and the other side is the S pole. For example, a magnetic pole pattern in which a plurality of sets of N poles and S poles are arranged in the circumferential direction of the magnet 3 may be used.

- The magnet 3 may have a magnetic pole pattern in which the N pole and the S pole are aligned in the thickness direction of the magnet 3 .
- The movable body 2 is not limited to a slide member that reciprocates linearly.

- The position detection device 1 is not limited to vehicle-mounted use, and can be used for other devices and devices.
- The number of bridge circuits 4 is not limited to one, and a plurality of bridge circuits may be provided.
- Although the present disclosure has been described with reference to examples, it is understood that the present disclosure is not limited to such examples or structures. The present disclosure also includes various modifications and modifications within the equivalent range. In addition, various combinations and configurations, as well as other combinations and configurations including single, more, or less elements thereof, are within the scope and spirit of this disclosure.

DESCRIPTION OF SYMBOLS 1... Position detection apparatus 2... Movable body 3... Magnet 4... Bridge circuit 7... Magnetic resistance element 7a... First magnetic resistance element 7b... Second magnetic resistance element 7c... Third magnetic resistance element 7d... Fourth magnetoresistive element, 8... First element pair, 9... Second element pair, 14... Intermediate point, 15... Intermediate point, 17... First element group, 18... Second element group, 23... Logic circuit , 24... Position determining section V1... First detection signal V2... Second detection signal E... Magnetic field R (R1 to R4)... Resistance value Vc... Power supply GND... Ground Sa... Differential signal Sb... Binary code.

Claims (6)

A bridge circuit is provided by assembling a plurality of magnetoresistive elements for detecting a magnet interlocking with a movable body in a bridge form, and a first detection signal detected from an intermediate point of a first element pair of the bridge circuit and the bridge A position detection device for detecting the position of the movable body by obtaining a difference from a second detection signal detected from an intermediate point of a second element pair of the circuit,
A position detecting device, wherein the resistance value of at least one of the plurality of magnetoresistive elements is set to a value different from the resistance values of the other magnetoresistive elements. 2. The position detecting device according to claim 1, wherein the magnetoresistive elements of the first element pair have different resistance values, and the magnetoresistive elements of the second element pair have different resistance values. The first element pair has a first magnetoresistive element connected to a terminal connected to a power supply and a second magnetoresistive element connected to a terminal connected to ground,
The second element pair has a third magnetoresistive element connected to the terminal connected to the ground and a fourth magnetoresistive element connected to the terminal connected to the power supply,
Of the first magnetoresistive element, the second magnetoresistive element, the third magnetoresistive element, and the fourth magnetoresistive element, each of the groups of the magnetoresistive elements facing the bridge is divided into the first element group and the fourth magnetoresistive element. 3. In the case of two element groups, the resistance value of each of the magnetoresistive elements of the first element group is set higher than the resistance value of each of the magnetoresistive elements of the second element group. 3. The position detection device according to 2. 4. The method according to claim 3, wherein the first magnetoresistive element and the third magnetoresistive element are set to the same resistance value, and the second magnetoresistive element and the fourth magnetoresistive element are set to the same resistance value. position detection device. The magnet is arranged such that when the movable body is at at least one of a movement start position and a movement end position, no magnetic field is applied to the bridge circuit or a weak magnetic field is applied to the bridge circuit. The position detection device according to any one of claims 1 to 4, which is arranged in the . a logic circuit that outputs a binary code based on the difference between the first detection signal and the second detection signal;
The position detection device according to any one of claims 1 to 5, further comprising a position determination unit that determines the position of the movable body based on the binary code input from the logic circuit.

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