WO2016111266A1

WO2016111266A1 - Position detecting device

Info

Publication number: WO2016111266A1
Application number: PCT/JP2016/050052
Authority: WO
Inventors: 健一古賀; 大谷　和也
Original assignee: 株式会社東海理化電機製作所
Priority date: 2015-01-06
Filing date: 2016-01-04
Publication date: 2016-07-14
Also published as: JP2016125940A

Abstract

This position detecting device (1) is provided with a first detecting coil (4) and a second detecting coil (5) to which AC voltage (VE) is applied from a power supply (3), and a position calculating unit (9) that calculates the position of a portion to be detected (2) on the basis of the distance from the position detecting device (1) and an object to be detected (6). The first and second detecting coils are disposed collaterally along a coil axial direction (K) such that the first detecting coil is located closer to the object to be detected, and the second detecting coil is located farther from the object to be detected. The position calculating unit (9) calculates the position of the portion to be detected on the basis of an output signal (V1) by the first detecting coil and an output signal by the second detecting coil.

Description

Position detection device

The present invention relates to a position detection device that detects the position of a detection target.

BACKGROUND Conventionally, a position detection device that detects the position of a detection target is known. Patent Document 1 describes a conventional example of a position detection device. The position detection device includes a detection coil disposed opposite to the metal portion interlocked with the detection portion, and changes in the distance between the detection coil and the metal portion when the detection portion moves, the inductance of the detection coil Based on changes in

Japanese Patent Application Publication No. 2007-505534

By the way, in this type of position detection device, the power supply voltage of the detection coil may fluctuate due to a change in the surrounding environment or the like. When the power supply voltage, that is, the voltage applied to the detection coil fluctuates, the output voltage of the detection coil changes, which hinders accurate position detection. Therefore, it is desirable to provide a mechanism for canceling the fluctuation of the power supply voltage. However, incorporating such a mechanism increases the space required for placement of the sensing coil.

An object of the present invention is to provide a position detection device capable of reducing the space required for the arrangement of detection coils.

One aspect of the present invention is a position detection device. The position detection device includes a position of the detection target having the detection target based on a first detection coil and a second detection coil to which an AC voltage is applied from a power supply, and a distance from the position detection device to the detection target. And a position calculation unit for calculating The first detection coil and the second detection coil are positioned such that the first detection coil is closer to the object to be detected, and the second detection coil is closer to the object to be detected The first detection coil is arranged side by side along a coil axis direction parallel to a coil axis of the first detection coil. The position calculation unit calculates the position of the detection target based on an output signal of the first detection coil and an output signal of the second detection coil.

According to this configuration, since the first detection coil and the second detection coil are arranged side by side in the coil axial direction, for example, compared with the case where the first detection coil and the second detection coil are arranged side by side in the planar direction, It is possible to reduce the area required for the arrangement of the coils.

According to the position detection device of the present invention, the space required for the arrangement of the detection coil can be reduced.

BRIEF DESCRIPTION OF THE DRAWINGS The schematic block diagram which shows the position detection apparatus of one Embodiment. The schematic side view of the board | substrate provided in the position detection apparatus of FIG. The schematic block diagram which shows the position detection apparatus of related technology. FIG. 7 is a schematic view illustrating the operation of the position detection device of FIG. 1; The wave form diagram which shows the inductance change when the current of the 1st detection coil and the 2nd detection coil is the same direction. The wave form diagram which shows voltage division ratio change when the current of the 1st detection coil and the 2nd detection coil is the same direction. The wave form diagram which shows the inductance change when the current of the 1st detection coil and the 2nd detection coil is reverse. FIG. 6 is a waveform diagram showing a change in voltage division ratio when the currents of the first detection coil and the second detection coil are in opposite directions.

Hereinafter, one embodiment of a position detection device will be described according to the drawings.
As shown in FIG. 1, the position detection device 1 is a type of an eddy current sensor that detects the position of the detection target 2 based on the distance from the position detection device 1 to the detection target 2. The position detection device 1 of the present example includes a first detection coil 4 and a second detection coil 5 to which an AC voltage Ve is applied from a power supply 3 of the position detection device 1. The to-be-detected part 2 includes the to-be-detected target 6 which changes the magnetic field generate | occur | produced in the 1st detection coil 4 and the 2nd detection coil 5 according to the motion of the to-be-detected part 2.

The to-be-detected object 6 consists of a metal plate which is a metal plate-shaped member, for example. In the present example, the detection target 6 is attached and fixed to the detection portion 2. Therefore, the detection target 6 moves integrally with the detection unit 2. The object to be detected 6 is arranged along the coil axis direction K (see the arrow in FIG. 1) parallel to the coil axis L of the first detection coil 4 (second detection coil 5) with the movement of the detection part 2 The linear reciprocation which approaches or estranges to 1 detection coil 4 is possible.

The first detection coil 4 and the second detection coil 5 are arranged side by side along the coil axis direction K. In the case of this example, the first detection coil 4 is disposed closer to the detection target 6, and the second detection coil 5 is disposed farther to the detection target 6. In other words, the first detection coil 4 and the second detection coil 5 are opposed to the sensor surface of the position detection device 1 which is the reference for detecting the distance to the detection portion 2 (that is, the position of the detection portion 2). The second detection coil 5 is disposed at a position farther from the sensor surface than the first detection coil 4. The sensor surface of the position detection device 1 is, for example, a coil surface of the first detection coil 4. Alternatively, the sensor surface may be a surface parallel to the coil surface of the first detection coil 4. The second detection coil 5 is provided as a reference coil for canceling the fluctuation of the voltage (power supply voltage) applied to the first detection coil 4. As described later, in this example, the output voltage (inductance) of each of the first and

second detection coils

4 and 5 is used as a signal for position detection in consideration of the fluctuation of the power supply voltage.

The first detection coil 4 and the second detection coil 5 are connected in series to the power supply 3. In this example, the first and

second detection coils

4 and 5 are disposed such that the direction of the current flowing through the first detection coil 4 and the direction of the current flowing through the second detection coil 5 are opposite to each other. Thereby, the magnetic field of the first detection coil 4 and the magnetic field of the second detection coil 5 are generated in opposite directions to each other. The first detection coil 4 and the second detection coil 5 are formed in the same area with the same number of turns.

A voltage detection unit 7 that detects a voltage between both ends of the first detection coil 4 is connected between input and output ends of the first detection coil 4. A voltage detection unit 8 for detecting a voltage between both ends of the second detection coil 5 is connected between input and output ends of the second detection coil 5. In this example, the output end of the second detection coil 5 is connected to the ground GND.

The position detection device 1 includes a position calculation unit 9 that calculates the position of the detection target 2 based on the output signal of the first detection coil 4 and the output signal of the second detection coil 5. In this example, the position calculation unit 9 is based on the output voltage V1 of the first detection coil 4 detected by the voltage detection unit 7 and the output voltage V2 of the second detection coil 5 detected by the voltage detection unit 8. The position of the detection target 2 is determined. For example, based on the value of V1 / V2 obtained by dividing the output voltage V1 of the first detection coil 4 by the output voltage V2 of the second detection coil 5, the position calculation unit 9 The distance to the detection target 6, that is, the position of the detection target 2 is determined.

As shown in FIG. 2, in this example, the first detection coil 4 and the second detection coil 5 are provided on the substrate 10. For example, the first detection coil 4 is provided on the first layer 10a of the substrate 10 (for example, the first surface of the substrate 10), and the second detection coil 5 is opposite to the second layer 10b of the substrate 10 (for example, the first surface). Provided on the second side). Therefore, the first and

second detection coils

4 and 5 are disposed on the same substrate 10 at a position where they overlap in plan view (as viewed from the coil axis direction K). The first detection coil 4 is formed only on the first layer 10 a of the substrate 10, and the second detection coil 5 is formed only on the second layer 10 b of the substrate 10.

Next, the operation of the position detection device 1 will be described using FIG. 3 to FIG.
FIG. 3 illustrates a related art position detection device 1A. Note that, in FIG. 3, the same components as those in FIG. 1 are denoted by the same reference numerals for easy understanding. The voltage of the power supply 3 may fluctuate depending on the ambient environment of the position detection device 1A. When the power supply voltage changes, the output voltage of the detection coils 4 and 5 also changes accordingly, which hinders accurate position detection. Therefore, in the position detection device 1A, the first detection coil 4 and the second detection coil 5 are arranged side by side in the planar direction so that the inductance of the second detection coil 5 used as a reference coil is always constant. The position detection device 1A performs time-division control of the connection state of the first and

second detection coils

4 and 5 with respect to the power supply 3 by the switch 15, and outputs (detection voltage) of the first detection coil 4 and the second detection. The output (detection voltage) of the coil 5 is obtained separately.

When the first detection coil 4 and the second detection coil 5 have the above-described arrangement, the inductance of the second detection coil 5 is constant regardless of the distance of the detection target 6 (metal plate). Therefore, the position detection device 1A can obtain the output (detection voltage) of the second detection coil 5 and cancel the fluctuation of the voltage of the power supply 3 based on the detection voltage. However, in the case of this arrangement, for example, a space for arranging the first detection coil 4 and the second detection coil 5 on the same surface of the substrate is required. Further, in order to keep the inductance of the second detection coil 5 constant, it is necessary to separate the second detection coil 5 from the detection target (the detection target 6) sufficiently in the planar direction. As a result, the arrangement space of the first and second detection coils 4 and 5, for example, the area of the substrate on which the

coils

4 and 5 are arranged, increases.

On the other hand, as shown in FIG. 4, in the position detection device 1 of this example, the first detection coil 4 and the second detection coil 5 are arranged side by side in the coil axial direction K and connected in series to the power supply 3. Therefore, even if the voltage of the power supply 3 fluctuates, the fluctuation of the power supply voltage affects both the output voltage V1 of the first detection coil 4 and the output voltage V2 of the second detection coil 5 at the same ratio. It becomes a thing. Therefore, the fluctuation of the power supply voltage is canceled by performing the position calculation using the output voltages V1 and V2 (in this example, the position calculation based on the division calculation). For this reason, if the position detection device 1 is used, it is possible to perform accurate position calculation taking into consideration fluctuations in the power supply voltage. Further, in the case of this example, since the first detection coil 4 and the second detection coil 5 are arranged side by side in the coil axis direction K, the arrangement space of the first and second detection coils 4 and 5, that is, the coil 4, It is also possible to minimize the area of the substrate 10 on which 5 is disposed.

FIG. 5 shows the first and second detection coils 4 and 5 in the case where the direction of the current flowing through the first detection coil 4 of the position detection device 1 is set to the same direction as the direction of the current flowing through the second detection coil 5. Indicate each inductance change. FIG. 6 shows a change in voltage division ratio of the first and second detection coils 4 and 5 in the case of FIG. As shown in FIGS. 5 and 6, when the direction of the current flowing through the first detection coil 4 is the same as the direction of the current flowing through the second detection coil 5, the distance to the detection target 6 increases (or decreases) ), The inductance of each

detection coil

4, 5 also increases (or decreases). For this reason, it is limited to increase the change of the voltage division ratio with respect to the change of the distance to the detection target 6.

FIG. 7 shows the first and second detection coils 4 and 5 in the case where the direction of the current flowing through the first detection coil 4 of the position detection device 1 is set in the opposite direction to the direction of the current flowing through the second detection coil 5. The inductance change of each of FIG. 8 illustrates the change in voltage division ratio of the first and second detection coils 4 and 5 in the case of FIG. 7. As shown in FIGS. 7 and 8, when the direction of the current flowing through the first detection coil 4 is opposite to the direction of the current flowing through the second detection coil 5, the distance to the detection target 6 increases (or As it decreases, the inductance of the detection coil 4 increases (or decreases), while the inductance of the detection coil 5 decreases (or increases). For this reason, it is possible to make the change of the voltage division ratio to the change of the distance to the detection target 6 large. Therefore, setting the direction of the current flowing through the first detection coil 4 and the second detection coil 5 in opposite directions is advantageous for detecting the position of the detection target 2 with high accuracy.

According to the configuration of the present embodiment, the following effects can be obtained.
(1) The position detection device 1 applies the AC voltage Ve from the power supply 3 to the first detection coil 4 and the second detection coil 5 arranged in line in the coil axial direction K (axial direction of the coil axis L). . Then, the position detection device 1 changes the output voltages V1 and V2 by using the output voltages V1 and V2 of the first detection coil 4 and the second detection coil 5 which change according to the distance to the detection target 2 Calculation for canceling (in this example, division calculation) is performed, and the position of the detection target 2 is detected based on the value obtained by the calculation. Here, even if the voltage of the power supply 3 fluctuates, the fluctuation of the power supply voltage affects both the output voltages V1 and V2 at the same ratio. Therefore, if division calculations etc. using output voltages V1 and V2 are performed, the fluctuation of the power supply voltage can be canceled, and the position of the detection target 2 is calculated based on the value where the fluctuation of the power supply voltage is canceled. Can. Therefore, even when the voltage of the power supply 3 fluctuates, it is advantageous to perform correct position detection. Further, in the case of this example, since the first detection coil 4 and the second detection coil 5 are arranged side by side in the coil axial direction K, for example, when the first detection coil 4 and the second detection coil 5 are arranged side by side in the plane direction Compared to the above, the space required for the arrangement of the first detection coil 4 and the second detection coil 5 can be reduced.

(2) The first detection coil 4 and the second detection coil 5 are formed on one substrate 10, that is, the same substrate 10. In this example, the first detection coil 4 is formed on the first layer 10 a of the substrate 10, and the second detection coil 5 is formed on the second layer 10 b of the substrate 10. If this configuration is adopted, the first detection coil 4 and the second detection coil 5 aligned in the coil axial direction K can be easily manufactured.

(3) The first detection coil 4 and the second detection coil 5 are connected in series. Therefore, a voltage can be applied to the first detection coil 4 and the second detection coil 5 by one power supply 3.
(4) The first detection coil 4 and the second detection coil 5 are arranged such that a magnetic field is generated in the reverse direction by the current flowing in the reverse direction in each of the

coils

4 and 5. Therefore, when the distance between the detection target 6 and the first detection coil 4 changes, the inductance of the first detection coil 4 and the inductance of the second detection coil 5 change in the opposite direction to each other. That is, if the inductance of the first detection coil 4 increases, the inductance of the second detection coil 5 decreases, and conversely, if the inductance of the first detection coil 4 decreases, the inductance of the second detection coil 5 increases. . Thus, when calculating (dividing) the position of the detection target 2, it is possible to increase the fluctuation range of the calculation result (division result). Therefore, it is advantageous to detect the position of the detection target 2 more correctly.

(5) The first detection coil 4 is formed on the first layer 10a of the substrate 10, the second detection coil 5 is formed on the second layer 10a of the substrate 10, and each of the first layer 10a and the second layer 10b is a single layer. It is one more layer. Therefore, since it is not necessary to form the first detection coil 4 across the plurality of layers of the substrate 10, the formation of the first detection coil 4 can be simplified. This is also true for the second detection coil 5.

(6) As a position detection device that detects the position of the detection target 2 from the output of the detection coil according to the approach or separation of the metal body (the detection target 6 of the detection target 2), mutual induction with the excitation coil There is a system that generates an induced electromotive force in a detection coil and detects the position of the detection target 2 based on the induced electromotive force that changes according to the distance to the detection target 6. As compared with the position detection device of this configuration, the position detection device 1 of this example causes the first detection coil 4 and the second detection coil 5 to oscillate directly, so the outputs of the first detection coil 4 and the second detection coil 5 Can be increased. Therefore, it is advantageous to easily detect the position of the detection target 2.

The above embodiment may be changed to the following modes.
The direction of the current flowing through the first detection coil 4 and the second detection coil 5 is not limited to the opposite direction, and may be the same direction. That is, if the

coils

4 and 5 are arranged side by side along the coil axis direction K, at least the advantage that the arrangement space of the

coils

4 and 5 can be reduced can be obtained. However, as described above, when the directions of the current flowing through the

coils

4 and 5 are the same, it is limited to increase the change in voltage division ratio of the

coils

4 and 5. Therefore, in order to detect the position of the detection target 2 more accurately while reducing the arrangement space of the

coils

4 and 5, it is more preferable that the direction of the current flowing through the

coils

4 and 5 be set in the opposite direction.

The first detection coil 4 and the second detection coil 5 may be arranged in an arrangement pattern in which they are not arranged on the same axial center in the coil axial direction K. In other words, the arrangement pattern in which the

coils

4 and 5 are arranged side by side along the coil axis direction K means not only the arrangement pattern in which the

coils

4 and 5 are arranged on the same axis but also a plan view (that is, the coils Also includes an arrangement pattern in which the

coils

4 and 5 are arranged so as to partially overlap each other in the axial direction K), and the axis of the coil 4 is offset from the axis of the coil 5. In the arrangement pattern in which the

coils

4 and 5 are disposed so as to partially overlap with each other, as compared with the arrangement pattern in which the

coils

4 and 5 are disposed side by side in the planar direction as shown in FIG. Can be made smaller.

The first detection coil 4 and the second detection coil 5 may have different shapes.
The coil shapes of the first detection coil 4 and the second detection coil 5 can be changed to other shapes than the square shape.

The substrate 10 may be a multilayer substrate, and the first detection coil 4 and the second detection coil 5 may be formed in different layers of the multilayer substrate.
The first detection coil 4 and the second detection coil 5 may each be formed across multiple layers of the substrate 10.

-While detecting the voltage (for example, V1 + V2) between the 1st detection coil 4 and the 2nd detection coil 5, the voltage (V2) of the 2nd detection coil 5 is detected, (V1 + V2) / V2 is made into the division value The position of the detection target 2 may be determined by finding it.

The connection between each of the first detection coil 4 and the second detection coil 5 and the voltage detection unit may be time-divisionally controlled by using a switch. For example, instead of the two voltage detection units 7 and 8, a single voltage detection unit and a single three-terminal switch may be used. In this case, for example, one end of the voltage detection unit is connected to the connection node between the

coils

4 and 5 and the other end is connected to the common terminal of the switch. Further, the first switching terminal of the switch is connected to the input end of the coil 4, and the second switching terminal of the switch is connected to the output end (ground GND) of the coil 5. Then, by time division control, the connection of the common terminal (the other end of the voltage detection unit) of the switch is switched between the first switching terminal (the input terminal of the coil 4) and the second switching terminal (ground GND). With this configuration, the number of voltage detection units required for the position detection device 1 can be reduced, which further contributes to downsizing of the position detection device 1.

The calculation performed to detect the position of the detection target 2 is not limited to the division of the output voltages V1 and V2, but may be changed to another calculation method.
The first detection coil 4 and the second detection coil 5 are not limited to being connected in series. For example, a dedicated power supply can be connected to each of the first detection coil 4 and the second detection coil 5, or the like, and other configuration can be appropriately changed.

The output signal of each of the

coils

4 and 5 used for position detection is not limited to the voltage value, and may be changed to another parameter such as a current value.
The detection target 6 is not limited to the metal plate, and may be changed to, for example, another member such as a coil.

Claims

A position detection device,
A first detection coil and a second detection coil to which an AC voltage is applied from a power supply;
And a position calculation unit that calculates the position of the detection target having the detection target based on the distance from the position detection device to the detection target.
The first detection coil and the second detection coil are positioned such that the first detection coil is closer to the object to be detected, and the second detection coil is closer to the object to be detected The first detection coil is arranged side by side along a coil axis direction parallel to a coil axis of the first detection coil;
The position detection device, wherein the position calculation unit calculates the position of the detection target based on an output signal of the first detection coil and an output signal of the second detection coil.
The position detection device according to claim 1, wherein the first detection coil and the second detection coil are formed on the same substrate.
The position detection device according to claim 1, wherein the first detection coil and the second detection coil are connected in series.
The first detection coil and the second detection coil are disposed such that a magnetic field is generated in the opposite direction by the current flowing in the opposite direction in each of the first and second detection coils. The position detection device according to any one of Items 1 to 3.
The first detection coil is formed on a first layer of the substrate,
The second detection coil is formed on a second layer of the substrate,
The position detection device according to claim 2, wherein each of the first layer and the second layer is a single layer.
The position detection device according to any one of claims 1 to 5, wherein the first detection coil and the second detection coil are disposed on the same axial center in the coil axial direction.
The first detection coil and the second detection coil are arranged such that the first and second detection coils partially overlap when viewed in the coil axis direction. The position detection device according to any one of the above.
The position calculation unit
A first output voltage indicating a voltage across the first detection coil is received as an output signal of the first detection coil, and a second output voltage indicating a voltage across the second detection coil is a voltage of the second detection coil. Received as an output signal,
The position of the detected portion is calculated based on a value obtained by performing division calculation that cancels each variation of the first output voltage and the second output voltage. The position detection device according to any one of the above.