JP2011185732A - Displacement detection device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an easily manufactured displacement detection device, reduced in production cost. <P>SOLUTION: Once angular displacement of a detection object 21 varies relative distances of the detection object 21 to first and second detection coils 25a and 25b, inductances of the first and second detection coils 25a and 25b change, varying oscillation frequencies of oscillation circuits 22. Since a signal processing section 23 outputs a reference electric signal converted into an electric signal equivalent to a displacement of the detection object 21, based on the oscillation frequency of each oscillation frequency, it is not necessary to coil around a displacement portion, no advanced processing technology is required for manufacturing, thereby allowing easier manufacturing and lower production costs. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a displacement detection device that outputs an electrical signal corresponding to the displacement of a detection object.

  FIG. 9 is a diagram schematically illustrating the wound resolver device 1 which is a displacement amount detection device. In the wound resolver device 1, each of the stator and the rotor includes an iron core and a winding. An excitation (REF) winding 2 is wound around the iron core of the stator, and a SIN winding 3 and a COS winding 4 are wound around the iron core of the rotor. When the excitation winding 2 is excited with an AC voltage, an AC output voltage is induced at the output terminal of the SIN winding 3 and the output terminal of the COS winding 4. When the alternating voltage for exciting the exciting winding 2 is Vsin ωt, the rotation angle of the rotor is θ, and the transformation ratio of the exciting winding 2, the SIN winding 3 and the COS winding 4 is k, respectively, the SIN winding 3 The AC voltage output from the output terminal is kVsinωt · sinθ, and the AC voltage output from the output terminal of the COS winding 4 is kVsinωt · cosθ. Moreover, you may reverse the relationship between a stator and a rotor (for example, refer patent document 1).

FIG. 10 is a diagram schematically illustrating the differential transformer device 10 that is a displacement amount detection device. The differential transformer 10 includes a primary coil 11, two secondary coils 12 and 13, and a movable iron core (core) 14 that magnetically couples the primary coil 11 and the two secondary coils 12 and 13. Consists of including. When the primary coil 11 is excited with an AC voltage, an AC output voltage is induced at each output terminal of the secondary coils 12 and 13. The output voltage induced at the output terminal of each secondary coil 12, 13 is proportional to the amount of displacement of the movable iron core, and the AC voltage that excites the primary coil 11 is Vsinωt, the output of the secondary coils 12, 13. The AC voltages output from the terminals are V _A sin ωt and V _B sin ωt, respectively (for example, see Patent Document 2).

Japanese Patent No. 2798340 JP-A-6-105487

  The above-described wire-wound resolver device 1 requires high-precision iron core processing technology and a special process for winding a large number of extra fine wires around the core slot. Advanced processing technology such as wire and skilled know-how are required. Therefore, there are problems that manufacturing is difficult and the unit price of the product becomes expensive.

  The differential transformer 10 described above also requires advanced processing technology and skilled know-how to wind the primary coil 11 and the secondary coils 12 and 13 respectively, which makes it difficult to manufacture and the unit price of the product. There is a problem that becomes expensive.

  Accordingly, an object of the present invention is to provide a displacement detection device that is easy to manufacture and can reduce production costs as compared with a wound resolver device and a differential transformer device.

The present invention each includes a detection coil whose inductance changes according to a change in the relative distance to the detection object, and a plurality of oscillation circuits whose oscillation frequency depends on the inductance of the detection coil;
A signal processing unit which receives an AC predetermined electrical signal and converts the predetermined electrical signal into an electrical signal corresponding to the amount of displacement of the object to be detected based on the oscillation frequency of each oscillation circuit. Is a displacement amount detecting device characterized by

Further, in the present invention, the detection object is provided such that one surface in the thickness direction faces each of the detection coils, and is angularly displaced around an axis line that is inclined with respect to the one surface,
At least two of the detection coils are provided at predetermined intervals around the axis.

The present invention further includes a reference coil provided at a position where the inductance is constant even when the detection object is displaced, and includes a second oscillation circuit whose oscillation frequency depends on the inductance of the reference coil,
One of the two detection coils is provided at a position where the other detection coil is angularly displaced by a predetermined angle around the axis,
The signal processing unit
A multiplier for multiplying each electrical signal oscillated by each oscillation circuit by the electrical signal oscillated by the second oscillation circuit;
Extracting the sine wave and cosine wave of the angular displacement of the detection object from the electrical signal obtained by the multiplication unit, respectively, and passing a part of the predetermined electrical signal based on the extracted sine wave and cosine wave, respectively. And a signal processing unit for outputting.

  According to the present invention, at least two of the coils are arranged in a predetermined direction, and when the oscillation frequency of the oscillation circuit including one coil increases as the detection object is displaced in the predetermined direction, An oscillation circuit including the coil is provided so as to reduce the oscillation frequency.

The present invention further includes a reference coil provided at a position where the inductance is constant even when the detection object is displaced, and includes a second oscillation circuit whose oscillation frequency depends on the inductance of the reference coil,
The signal processing unit
A multiplier for multiplying the electrical signal oscillated by the oscillation circuit by the electrical signal oscillated by the second oscillation circuit;
A voltage corresponding to the increase and decrease of the oscillation frequency in each oscillation circuit is extracted from the electrical signal obtained by the multiplication unit, and a part of the predetermined electrical signal is output based on the extracted voltage. And a signal processing unit.

  In the invention, it is preferable that the signal processing unit includes a power acquisition unit that rectifies a predetermined electrical signal to acquire power.

  According to the present invention, when the relative distance between the detection object and the detection coil changes due to the displacement of the detection object, the inductance of the detection coil changes. Since the oscillation frequency of the oscillation circuit depends on the inductance of the detection coil, when the inductance of the detection coil changes, the oscillation frequency of the oscillation circuit changes. Based on the oscillation frequency of each oscillation circuit, the predetermined electrical signal is converted into an electrical signal corresponding to the amount of displacement of the object to be detected and output, so that it is displaced as compared with the conventional winding resolver device 1. It is not necessary to wind a coil around the portion, and a primary coil is not necessary as compared with the differential transformer 10. In the configuration in which the coil is wound around the portion to be displaced and the configuration in which the primary coil is wound, an advanced processing technique is required. However, in the present invention, such a configuration is not required. Even if it is not, a displacement amount detection device can be configured, manufacturing becomes easy, and production cost can be reduced.

  In addition, as a signal processing unit, a signal similar to the reference signal energized to the stator side winding and the primary coil in the prior art is input as a predetermined electric signal, and a part of the predetermined electric signal is oscillated. Any configuration that can output based on the oscillation frequency of the circuit may be used. Such a circuit configuration is simple, a highly accurate processing circuit can be easily realized, and a highly reliable displacement detection device can be realized. Can be configured.

  Further, according to the present invention, the object to be detected is plate-shaped, and one surface in the thickness direction is provided facing each coil, and is angularly displaced around an axis line that is inclined with respect to the one surface, so that at least two of the detections are performed. The coil for detection is arranged at a predetermined interval around the axis, whereby the electrical signal output from the oscillation circuit connected to one of the two detection coils and the other detection The frequency of the electric signal output from the oscillation circuit connected to the coil for use can be made different. Based on these two electric signals having different frequencies, the signal processing unit converts the electric signal predetermined by the signal processing unit into an electric signal corresponding to the amount of displacement of the object to be detected. An electrical signal representing a rotation angle equivalent to the two output signals can be output, thereby realizing a device having the same function as that of the winding resolver device. Therefore, it is possible to realize a low-cost displacement detection device that can replace the current winding type resolver without any special manufacturing technique.

  According to the invention, the electrical signal oscillated by the second oscillation circuit by the multiplication unit is multiplied by the electrical signal oscillated by the oscillation circuit, and the signal processing unit uses the electrical signal obtained by the multiplication unit to The sine wave and cosine wave of angular displacement are extracted, respectively, and a part of the predetermined electrical signal is output based on the extracted sine wave and cosine wave. Can be less affected by In addition, one of the two detection coils is provided at a position where the other detection coil is displaced by a predetermined angle around the axis, for example, 90 degrees, thereby performing signal processing. The unit can easily extract the sine wave and the cosine wave of the angular displacement of the detection target from the electrical signal obtained by the multiplication unit. An electric signal representing a rotation angle equivalent to the two output signals of the winding resolver by the signal processing unit passing through and outputting a part of the predetermined electric signal based on each of the extracted sine wave and cosine wave. A signal is output.

  According to the present invention, when the detection object is displaced in a predetermined direction, the oscillation frequency of the oscillation circuit including one of the two coils arranged in the predetermined direction is increased, and the other coil is provided. The oscillation frequency of the oscillation circuit decreases, and the oscillation frequency of each oscillation circuit changes according to the amount of displacement of the detection object in a predetermined direction. Based on the change in the oscillation frequency of each oscillation circuit in accordance with the amount of displacement of the detection target in a predetermined direction, the signal processing unit converts the predetermined electrical signal into an electrical signal corresponding to the amount of displacement of the detection target. Thus, the signal processing unit can output an electrical signal representing a displacement equivalent to the two output signals of the differential transformer, thereby realizing a device having the same function as the differential transformer. be able to. Therefore, it is possible to realize a low-cost displacement detection device that can replace the current differential transformer without any special manufacturing technique.

  Further, according to the present invention, the electrical signal oscillated in the second oscillation circuit by the multiplication unit is multiplied by the electrical signal oscillated in the oscillation circuit, and the oscillation in each oscillation circuit is performed from the electrical signal obtained by the multiplication unit by the signal processing unit. Voltages are extracted according to frequency increases and decreases, and some of the predetermined electrical signals are output based on the extracted voltages, so that they are influenced by the oscillation frequency due to environmental changes such as ambient temperature. Can be difficult. The signal processing unit extracts a voltage corresponding to the increase and decrease of the oscillation frequency in each oscillation circuit from the electrical signal obtained by the multiplication unit, and outputs a part of the predetermined electrical signal based on the extracted voltage. Thus, the signal processing unit outputs a signal representing a displacement amount equivalent to the two output signals of the differential transformer.

  Further, according to the present invention, the electric power for operating the signal processing unit is generated by rectifying a predetermined electric signal, so there is no need to provide a separate power source, and the apparatus can be further simplified. Cost reduction can be achieved. Further, since a power source is not required, it can be used as it is instead of a conventional displacement amount detection device.

It is a figure which shows the structure of the displacement amount detection apparatus 20 of one Embodiment of this invention. 3 is a plan view of a detection target 21. FIG. 4 is a diagram for explaining a relationship between a relative distance between a detection object 21 and a coil 25 and an oscillation frequency of an oscillation circuit 22. FIG. 3 is a graph schematically showing a relationship between a relative distance between a detection object 21 and a coil 25 and an oscillation frequency of an oscillation circuit 22; 3 is a circuit diagram schematically showing an oscillation circuit 22. FIG. It is a figure explaining the operation | movement in the 1st and 2nd gate parts 35 and 36. FIG. FIG. 7 is a waveform diagram for explaining a signal processing procedure for generating output signals of the first and second gate sections 35 and 36. FIG. 7A is an input diagram of the first and second gate sections 35 and 36. 7 (2) shows the reference pulse signal waveform synchronized with the input signal of FIG. 7 (1), FIG. 7 (3) shows the cut-off signal waveform, and FIG. 7 (4) shows the cut-out signal waveform. The output signal waveform is shown. It is a figure which shows the structure of the displacement amount detection apparatus 50 of other form of implementation of this invention. It is a figure which simplifies and shows the winding-type resolver apparatus 1 which is a displacement amount detection apparatus. It is the figure which simplifies and shows the differential transformer device 10 which is a displacement amount detection apparatus.

  FIG. 1 is a diagram showing a configuration of a displacement amount detection apparatus 20 according to an embodiment of the present invention. FIG. 2 is a plan view of the detection target 21. In FIG. 1, the detection target 21 is also illustrated for easy understanding. The displacement amount detection device 20 is an electronic resolver device, and has the same function as that of the winding type resolver device. The displacement amount detection device 20 detects an angular displacement amount, that is, a rotation angle, of the detection target 21, and an electric amount corresponding to the angular displacement amount. Output a signal. Further, the second detection coil 25b and the reference coil 25r are actually overlapped in FIG. 1, but are illustrated separately for easy understanding.

  The displacement amount detection device 20 includes a plurality of oscillation circuits 22a, 22b, and 22r (hereinafter, the subscripts a, b, and r are omitted when collectively referred to) and a signal processing unit 23. The detection target 21 is formed of a magnetic material such as metal.

  The oscillation circuit 22 outputs a sine wave electric signal having the same frequency as the oscillation frequency. The oscillation circuit 22 includes coils 25a, 25b, and 25r whose inductance changes in accordance with a change in the relative distance to the detection target 21 (hereinafter, the suffixes a, b, and r are omitted when collectively referred to). Composed.

  The coil 25 includes first and second detection coils 25a and 25b and a reference coil 25r. The first and second detection coils 25a and 25b and the reference coil 25r are formed such that electrical characteristics such as inductance are equal to each other. The first and second detection coils 25a and 25b and the reference coil 25r are arranged, for example, on one surface of a plate-like printed wiring board, and the reference coil 25r is arranged on one surface of the printed wiring board. They are arranged on a concentric circle centered on the magnetic axis and having a radius R with an interval of 90 °. The first and second detection coils 25 a and 25 b and the reference coil 25 r are provided facing the detection target 21. The end surfaces of the first and second detection coils 25a and 25b that face the detection target 21 and the end surfaces of the reference coil 25r that face the detection target 21 are perpendicular to the magnetic axes of the coils 25a, 25b, and 25r. Each is provided on a plane. The coil 25 is formed by winding an electric wire around a substantially cylindrical bobbin. The coils 25 are arranged at intervals on one surface of the printed wiring board so that the magnetic axes are perpendicular to the one surface of the printed wiring board.

  The detection target 21 is formed in a plate shape, and has a disk shape in the present embodiment. The detection object 21 is provided with the coil 25 facing one surface 21a in the thickness direction. The one surface 21a is formed in a plane. The detection target object 21 has the one surface 21a of the detection target object 21 with respect to a second virtual plane perpendicular to the first virtual plane and perpendicular to the axis L parallel to the magnetic axis of the reference coil 25r. In a state where the angle φ is tilted in advance, the rotation is arranged around the axis L. The axis L is arranged on a straight line on which the magnetic axis of the reference coil 25r extends. Therefore, the relative distance xr between the reference coil 25r and the detection target 21 is unchanged (xr = xo) even if the detection target 21 is angularly displaced about the axis L. Hereinafter, when the relative distance x1 between the first detection coil 25a and the detection object 21 is the smallest (x1 = xo−R × tanφ), it is referred to as a reference position of the detection object 21. If the amount of angular displacement around the axis L from the reference position is θ, the relative distance xr between the reference coil 25r and the detection target object 21, the relative distance x1 between the first detection coil 25a and the detection target object 21, and the first 2 The relative distance x2 between the detection coil 25b and the detection object 21 is expressed by the following equation (1).

  The oscillation frequency of each oscillation circuit 22 depends on the inductance of the coil 25. That is, the frequency of the sine wave output from the oscillation circuit 22 changes according to the relative distance between the detection target 21 and the coil 25. The signal processing unit 23 outputs an electrical signal corresponding to the angular displacement amount of the detection target 21 based on the frequency of the sine wave given from each oscillation circuit 22.

  FIG. 3 is a diagram for explaining the relationship between the relative distance between the detection target 21 and the coil 25 and the oscillation frequency of the oscillation circuit 22. FIG. 4 is a graph schematically showing the relationship between the relative distance between the detection object 21 and the coil 25 and the oscillation frequency of the oscillation circuit 22. In FIG. 4, the horizontal axis represents the relative distance between the detection target 21 and the coil 25, and the vertical axis represents the frequency. The relationship between the relative distance between the detection object 21 and the coil 25 and the oscillation frequency of the oscillation circuit 22 indicated by the solid line 26 in FIG. 4 oscillates every time the relative distance between the detection object 21 and the coil 25 is changed. It is obtained by measuring the oscillation frequency of the circuit 22. Using this graph, the relative distance between the detection object 21 and the coil 25 can be calculated based on the oscillation frequency of the oscillation circuit 22.

The oscillation frequency f when it is slightly displaced from the reference relative distance xo is expressed by the following equation (3).
f (x) = a0 + a1 (x−xo) = a0 + a1 × Δx (3)
In Expression (3), a1 is a proportionality coefficient, and a displacement (x-xo) from a reference relative distance xo is Δx.

  FIG. 5 is a circuit diagram schematically showing the oscillation circuit 22. The oscillation circuit 22 according to the present embodiment includes a tank circuit 41 and a negative resistance element 42. The tank circuit 41 is configured by connecting a coil 25 and a capacitor 43 in parallel. The negative resistance element 42 and the tank circuit 41 are connected in parallel. Although the coil 25 is illustrated as an ideal coil in FIG. 5, the coil 25 actually includes a resistance component. The ideal tank circuit 41 does not consume power, but in the actual tank circuit 41, power is consumed by the resistance component. Since the consumed electric power is replenished by the negative resistance element 42, oscillation occurs at the resonance frequency of the tank circuit 41. The oscillation frequency of the oscillation circuit 22 substantially matches the resonance frequency of the tank circuit 41. The resonance frequency of the tank circuit 41 depends on the inductance of the coil 25, and the inductance of the coil 25 depends on the relative distance to the detection target 21. Therefore, as shown in FIG. 4, the oscillation frequency of the oscillation circuit 22 changes according to a change in the relative distance between the coil 25 and the detection target 21. The negative resistance element 42 is realized including, for example, an operational amplifier and an amplifier such as a transistor.

  When the oscillation frequency of the oscillation circuit 22 having the reference coil 25r (hereinafter sometimes referred to as reference oscillation circuit 22r) is fr, the oscillation circuit 22 having the first detection coil 25a (hereinafter referred to as first oscillation circuit 22a). The oscillation frequency of the oscillation circuit 22 having the second detection coil 25b (hereinafter, sometimes referred to as the second oscillation circuit 22b) is f2, and the relative distance xr in the equation (1) is defined as f2. , X1 and x2 are respectively substituted into the equation (3), the oscillation frequency of each oscillation circuit 22 is represented by the following equation (4).

  In formula (4), a1 (−R × tanφ) was set as A as an invariant constant. Since the inductance of the coil 25 is inversely proportional to the distance to the detection target 21, and the oscillation frequency is inversely proportional to the inductance, the oscillation frequency can be approximated by a linear function of the distance as shown in the above-described equation (4). . In equation (4), a0 and A change depending on the temperature factor.

  The signal processing unit 23 outputs an electrical signal corresponding to the angular displacement amount of the detection target 21 based on the electrical signal output from each oscillation circuit 22. The signal processing unit 23 includes a first multiplication unit 31, a second multiplication unit 32, a first low-pass filter 33, a second low-pass filter 34, a first gate unit 35, and a second gate unit 36. It is comprised including.

  The first multiplier 31 is connected to the first oscillation circuit 22a and the reference oscillation circuit 22r, and outputs an electrical signal output from the first oscillation circuit 22a and an electrical signal output from the reference oscillation circuit 22r. By performing multiplication, synchronous rectification is performed, and the multiplied electric signal is supplied to the first low-pass filter 33. The following equation (8) shows an electric signal given to the first low-pass filter 33.

  In Expression (5), t represents time, φ1 represents the initial phase of the electrical signal output from the first oscillation circuit 22a, and φr represents the initial phase of the electrical signal output from the reference oscillation circuit 22r. To express. The first multiplication unit 31 is connected to the first low-pass filter 33. As shown in Expression (5), the electrical signal supplied to the first low-pass filter 33 is a superposition of a low-frequency cosine wave having a frequency of | f1-fr | and a high-frequency cosine wave having a frequency of f1 + fr. It is a combination.

  The first low-pass filter 33 removes the high-frequency cosine wave of the second term on the right side of Equation (5) and passes the low-frequency cosine wave of the first term on the right side to pass the first gate unit 35. To give. The first gate unit 35 is connected to the first low-pass filter 33. The cutoff frequency of the first low-pass filter 33 is selected between the frequency of the first term on the right side and the frequency of the second term on the right side of Equation (5), for example, when the detection target 21 is at the reference position. {(F1 + fr) + | f1-fr |} / 2.

  The frequency of the electrical signal output from the first low-pass filter 33 is | f1-fr | = | a0 + A × cos θ−a0 | = A × cos θ, and the cosine wave is extracted by the first low-pass filter 33. The electric signal of the cosine wave is given to the first gate unit 35.

  The second multiplier 32 is connected to the second oscillation circuit 22b and the reference oscillation circuit 22r, and outputs a sine wave output from the second oscillation circuit 22b and a sine wave output from the reference oscillation circuit 22r. Multiply and provide the multiplied electrical signal to the second low pass filter 34. The following equation (6) shows an electric signal given to the second low-pass filter 34.

  In Expression (6), φ2 represents the initial phase of the sine wave output from the second oscillation circuit 22b. The second multiplier 32 is connected to the second low pass filter 34. As shown in Expression (6), the electrical signal supplied to the second low-pass filter 34 is a superposition of a low-frequency cosine wave having a frequency of | f2-fr | and a high-frequency cosine wave having a frequency of f2 + fr. It is a combination.

  The second low-pass filter 34 removes the high-frequency cosine wave of the second term on the right side of Equation (6) and passes the low-frequency cosine wave of the first term on the right side to pass the second gate unit 36. To give. The second gate unit 36 is connected to the second low-pass filter 34. The cutoff frequency of the second low-pass filter 34 is selected between the frequency of the first term on the right side and the frequency of the second term on the right side of Equation (6), for example, when the detection target 21 is at the reference position. {(F2 + fr) + | f2-fr |} / 2.

  The frequency output from the second low-pass filter 34 is | f2-fr | = | a0 + A × sin θ−a0 | = A × sin θ, and a sine wave is extracted by the second low-pass filter 34. A wave electric signal is applied to the second gate portion 36.

  Reference signals, which are predetermined electrical signals, are individually supplied to the first and second gate portions 35 and 36, respectively, and the cosine wave is supplied to the first gate portion 35 from the first low-pass filter 33. , And the second gate unit 36 is supplied with the sine wave electric signal from the second low-pass filter 34.

  FIG. 6 is a diagram for explaining operations in the first and second gate portions 35 and 36. First, FIG. 6A shows the waveform of a reference electric signal. FIG. 6 (2) shows an example of a waveform of an electrical signal output from the signal processing unit 23, which is a waveform obtained by cutting out a part of the electrical signal for reference. 6 (1) and (2), the vertical axis represents voltage, and the horizontal axis represents phase.

  The wound resolver device is supplied with an electrical signal for excitation, and outputs an electrical signal proportional to its sine and cosine according to the rotation angle. By processing these electrical signals proportional to the sine and cosine with a signal converter represented by a resolver digital (RD) converter, a detection amount proportional to the rotation angle can be obtained. The wound resolver device uses a voltage induced in the secondary winding by the principle of a rotary transformer, but in order to obtain an equivalent function, for a given electrical signal for reference, As shown by the hatched portion in FIG. 6 (2), a waveform obtained by cutting out a part thereof is considered. The electrical signal for reference in the present embodiment corresponds to the electrical signal for excitation in the winding resolver device.

  The reference electrical signal is represented by the following formula (7), and in the section of one wavelength of the reference electrical signal shown in FIG. 6 (2), the section from −π / 2−α to −π / 2, from −α When the fundamental wave component of the waveform when the section of + α and the section of π / 2 to π / 2 + α are cut out is obtained, the fundamental wave component a1 of the shaded portion waveform is expressed by the following equation (8). α is selected such that 0 ≦ α ≦ π / 2. Here, the sine wave electric signal for reference is Vr, and the fundamental wave component of the shaded portion waveform is a1. The fundamental wave component a1 of the shaded portion waveform is a Fourier series coefficient. The voltage is V.

Vr = V · cos ωt (7)
a1 = ∫Vr · cos ωt · d (ωt)
= ∫V · cos ² ωt · d (ωt) (8)

Here, when each section of the hatched portion is calculated, the following (a) to (c) are obtained.
(A) Calculated value from -α to + α section: A1 = α + (sin2α) / 2
(B) Calculated value in the interval from π / 2 to π / 2 + α: A2 = α / 2− (sin2α) / 4
(C) Calculated value between -π / 2-α and -π / 2: A3 = α / 2- (sin2α) / 4
Therefore,
a1 = A1 + A2 + A3 = 2α
It becomes.

  Therefore, if the amounts corresponding to sin θ and cos θ representing the angular displacement amounts extracted by the first and second low-pass filters 33 and 34 are output so as to be 2α, the fundamental wave of these electric signals is output. The components are output signals corresponding to the sine and cosine of the excitation signal in the wound resolver device.

  FIG. 7 is a waveform diagram for explaining a signal processing procedure for generating output signals of the first and second gate sections 35 and 36. FIG. 7A is an input diagram of the first and second gate sections 35 and 36. 7 (2) shows the reference pulse signal waveform synchronized with the input signal of FIG. 7 (1), FIG. 7 (3) shows the cut-off signal waveform, and FIG. 7 (4) shows the cut-out signal waveform. The output signal waveform is shown. A reference pulse signal with a period of 2T shown in FIG. 7B is generated by the waveform shaping circuit.

  The reference pulse signal generated by the waveform shaping circuit is input to a cut-off signal generation circuit realized by a logic circuit such as a counter circuit. The cut-off signal generation circuit causes the first pulse signal to be generated from the low-pass filters 33 and 34. Based on the cos component extraction signal and the sin component extraction signal input to the second gate units 35 and 36, a cutoff signal shown in FIG. 7 (3) is generated. By using such a cut-off signal, for example, by switching the conduction / shut-off operation of the analog switch, the signal shown in FIG. 7 (4) from the input signal shown in FIG. A waveform signal corresponding to AVsin (ωt) × cos θ, and a waveform signal corresponding to AVsin (ωt) × sin θ can be cut out and output from the second gate unit 36.

  The fundamental component of the electrical signal output from the first and second gate sections 35 and 36 is obtained by passing the original electrical signal, that is, the electrical signal having the waveform shown in FIG. 6 (2), through the low-pass filter. . Also in the winding type resolver device used in the prior art, the signal processing circuit for processing the electric signal output from the winding type resolver device has a synchronous multiplication unit inside the signal processing circuit, and the winding type resolver device Since the signal processing is performed by extracting the fundamental wave component of the electrical signal given from the displacement amount detection device 20, it is not necessary to include a circuit for extracting the fundamental wave component. That is, by outputting the waveform shown in FIG. 6 (2) as it is, the displacement detection device 20 can simulate a winding resolver device.

  The signal processing unit 23 is provided with a rectifying / smoothing circuit 37 which is a power acquisition unit that rectifies a reference electrical signal to acquire power. The rectifying / smoothing circuit 37 converts a reference AC signal into a direct current, and is realized by, for example, a choke input single-phase full-wave rectifier circuit. The rectifying / smoothing circuit 37 is a power source for each part of the signal processing unit 23, the first and second multiplication units 31, 32, the first and second low-pass filters 33, 34, and the first and second gate units 35, 36. The power is supplied by applying a DC voltage to each of these parts. The rectifying / smoothing circuit 37 may supply power to the oscillation circuit 22 as well.

  As described above, in the displacement amount detection device 20, if the relative distance between the detection target 21 and the first and second detection coils 25a and 25b changes due to the angular displacement of the detection target 21, the first and first 2 The inductances of the detection coils 25a and 25b change. Since the oscillation frequency of the oscillation circuit 22 depends on the inductances of the first and second detection coils 25a and 25b, the oscillation frequency of the oscillation circuit 22 changes when the inductances of the first and second detection coils 25a and 25b change. Change. Based on the oscillation frequency of each oscillation circuit 22, the reference electrical signal is converted into an electrical signal corresponding to the amount of displacement of the detection target 21 and output, so when compared with the conventional winding resolver device 1, Since it is not necessary to wind a coil around the portion to be displaced, and advanced processing technology is not required for manufacturing, manufacturing is facilitated and production cost can be reduced.

  In addition, as the signal processing unit 23, a signal similar to the reference signal energized in the stator side winding in the winding type resolver device of the prior art is input as a predetermined electric signal, and a part of the predetermined electric signal is input. What is necessary is just to set it as the structure cut out, Such a circuit structure is simple, a highly accurate processing circuit can be implement | achieved easily, and a highly reliable displacement detection apparatus can be comprised.

  Further, one surface 21a in the thickness direction of the detection target 21 is provided facing the first and second detection coils 25a and 25b, and is angularly displaced about an axis L that is inclined with respect to the one surface 21a. The second detection coils 25a and 25b are connected to one coil 25 of the first and second detection coils 25a and 25b by being arranged at predetermined intervals around the axis L. The phases of the electrical signal output from the oscillation circuit 22 and the electrical signal output from the oscillation circuit 22 connected to the other coil 25 can be made different. Based on these two electrical signals having different phases, the signal processing unit 23 converts a predetermined electrical signal into an electrical signal corresponding to the amount of displacement of the detection target 21, so that the signal processing unit 23 has a winding type. An electrical signal representing a rotation angle equivalent to the two output signals of the resolver device can be output, thereby realizing a device having the same function as that of the wire wound resolver device. Therefore, it is possible to realize a low-cost displacement detection device 20 that can replace the current winding type resolver without any special manufacturing technique.

  The signal processing unit multiplies the electric signal oscillated by the first and second oscillation circuits 22a and 22b by the electric signal oscillated by the first and second oscillation circuits 22a and 22b by the first and second multiplication units 31 and 32. The sine wave and cosine wave are respectively extracted from the electrical signal obtained in the unit, and a part of the predetermined electrical signal is output based on the extracted sine wave and cosine wave, respectively. It can be made difficult to be affected by the change in the oscillation frequency. In addition, one of the first and second detection coils 25a and 25b is provided at a position where the other coil 25 is angularly displaced by 90 degrees around the axis L, thereby a signal processing unit. 23 can easily extract a cosine wave and a sine wave from the electric signals obtained by the multipliers 31 and 32, respectively. The signal processing unit 23 outputs a rotation angle equivalent to the two output signals of the winding resolver by passing a part of the predetermined electrical signal based on each of the extracted sine wave and cosine wave and outputting the signal. An electrical signal is output.

  In addition, since the electric power for operating the signal processing unit 23 is generated by rectifying the electric signal for reference, it is not necessary to provide a separate power source, and the apparatus can be simplified and the cost can be reduced. Can be achieved. Further, since a power source is not required, it can be used as it is instead of the conventional winding resolver device.

  FIG. 8 is a diagram showing a configuration of a displacement amount detection device 50 according to another embodiment of the present invention. In FIG. 8, the detection target 51 is also illustrated for easy understanding. The displacement amount detection device 50 has the same function as that of the differential transformer, and detects the displacement amount of the detection object 51 in a predetermined direction. The displacement amount detection device 50 is different from the displacement amount detection device 20 described above only in the arrangement relationship between the coils 25 and the detection object 51, and the other configurations are the same. Parts similar to those in the above-described configuration may be denoted by the same reference numerals and description thereof may be omitted.

  The displacement detection device 50 includes a plurality of oscillation circuits 22 and a signal processing unit 23. The detection target object 51 is formed of a magnetic material such as metal.

  Each oscillation circuit 22 is provided, for example, on a plate-like printed wiring board. The coil 25 is formed by winding an electric wire around a substantially cylindrical bobbin. The coils 25 are arranged on the one surface of the printed wiring board at equal intervals in the predetermined direction so that the magnetic axis is perpendicular to the one surface in the thickness direction of the printed wiring board. Each coil 25 is formed so that electrical characteristics such as inductance are equal to each other. Hereinafter, the direction in which the coils 25 are arranged is referred to as an arrangement direction Y. The first detection coil 25a is disposed at one end Y1 of the coils 25 in the arrangement direction Y, and the second detection coil 25b is disposed at the other end Y2 of the coils 25 in the arrangement direction Y. The reference coil 25r is arranged at the center in the arrangement direction Y of the coils 25.

  The reference coil 25r is provided at a position where the distance from the detection target object 51 is constant even when the detection target object 51 is displaced in the use state. When the detection object 51 moves from the reference position to one Y1 in the arrangement direction Y, the first detection coil 25a has a strong magnetic coupling with the detection object 51, and the detection object 51 is arranged from the reference position. It is provided at a position where the degree of magnetic coupling with the detection object 51 is weakened when moving in the other direction Y2 in the direction Y. In addition, the second detection coil 25b has a weak magnetic coupling with the detection target 51 when the detection target 51 moves from the reference position to one Y1 in the arrangement direction Y, and the detection target 51 moves from the reference position. It is provided at a position where the degree of magnetic coupling with the detection target object 51 increases when it moves in the other direction Y2 of the arrangement direction Y. That is, when the detection target 51 is displaced and the degree of magnetic coupling between the first coil 25 and the detection target 51 among the first and second detection coils 25a and 25b increases, The degree of magnetic coupling with the detection object 51 is weakened.

  The detection target object 51 has, for example, a rod-like substantially quadrangular prism shape. The one side surface 51 a faces each coil 25 of the detection target 51, and the one side surface 51 a is provided so as to be parallel to the arrangement direction Y. The detection target 51 is arranged so that the direction in which the detection target 51 extends coincides with the arrangement direction Y described above, and the one side surface 51a faces one surface in the thickness direction of the printed wiring board. Hereinafter, the position of the detection target object 51 when the central portion 57 is located at the position where the magnetic axis of the reference coil 25r extends is defined as a reference position. The displacement amount detection device 50 detects the displacement amount in the arrangement direction Y from the reference position of the detection target object 51.

  When the detection object 51 moves from the reference position to one Y1 in the arrangement direction Y, the inductance of the first detection coil 25a changes so as to be larger than that at the reference position, and the inductance of the second detection coil 25b becomes the reference. As a result, the oscillation frequency of the first oscillation circuit 22a is lower than that at the reference position, and the oscillation frequency of the second oscillation circuit 22b is higher than that at the reference position. Become. Further, when the detection object 51 moves from the reference position to the other Y2 in the arrangement direction Y, the inductance of the first detection coil 25a changes so as to be smaller than that at the reference position, and the inductance of the second detection coil 25b becomes smaller. As a result, the oscillation frequency of the first oscillation circuit 22a is higher than that at the reference position, and the oscillation frequency of the second oscillation circuit 22b is higher than that at the reference position. Lower.

  The signal processing unit 23 outputs an electrical signal corresponding to the amount of displacement of the detection target object 51 based on the sine wave output from each oscillation circuit 22. The first multiplication unit 31 multiplies the sine wave output from the first oscillation circuit 22 a and the sine wave output from the reference oscillation circuit 22 r and supplies the multiplied electric signal to the first low-pass filter 33. . The second multiplication unit 32 multiplies the sine wave output from the second oscillation circuit 22b and the sine wave output from the reference oscillation circuit 22r, and supplies the multiplied electric signal to the second low-pass filter 34. .

  The first and second low-pass filters 33 and 34 extract the low-frequency components of the electrical signals given from the first and second multipliers 31 and 32, respectively, and the first and second gate units 35 and 35, respectively. 36 to give each.

Based on the electrical signal supplied from the first low-pass filter 33, the first gate unit 35 outputs an electrical signal in which α corresponds to the amount of displacement in the Y direction, as shown in FIG. Therefore, when Vsinωt is input as a reference electrical signal, the first gate unit 35 outputs an electrical signal representing V _A sinωt corresponding to the displacement amount.

Based on the electrical signal supplied from the second low-pass filter 34, the second gate unit 36 outputs an electrical signal in which α corresponds to the amount of displacement in the Y direction, as shown in FIG. Therefore, when Vsin ωt is input as a reference electric signal, the second gate portion 36 outputs an electric signal representing V _B sin ωt corresponding to the amount of displacement.

In the displacement amount detection device 50 described above, when the electrical signal Vsinωt for reference is input, the signal processing unit 23 outputs electrical signals representing the two electrical signals V _A sinωt and V _B sinωt. This is equivalent to the differential transformer of the prior art, whereby the differential transformer of the prior art can be replaced with the displacement detector 50 of the present embodiment as it is, and the displacement can be detected. Therefore, the measuring instrument that measures the displacement amount using the electrical signal output from the displacement amount detection device 50 can be used as it is without any change.

  In the displacement amount detection device according to still another embodiment of the present invention, each of the displacement amount detection devices 20 and 50 according to each embodiment described above may include the detection objects 21 and 51.

  The reference coils 25r in the displacement detection devices 20 and 50 of the above-described embodiments are arranged so that the relative distance to the detection objects 21 and 51 is not changed, but the detection objects 21 and 51 are It may be arranged at a position where the relative distance changes when displaced. Even if the detection coils 25a and 25b are arranged in this way, the angular displacement θ around the axis L of the detection target 21 or the detection target as in the displacement detection devices of the above-described embodiments. It is possible to output an electrical signal corresponding to the amount of displacement 51 in the arrangement direction Y.

  Further, the first detection coil 25a and the second detection coil 25b are respectively arranged at 90 ° intervals on concentric circles having a radius R and centered on the magnetic axis of the reference coil 25r. However, any angle other than 180 ° may be used. Even if each of the detection coils 25a and 25b is arranged in this way, the electrical corresponding to the angular displacement θ around the axis L of the detection target 21 is the same as the displacement detection device 20 of each of the embodiments described above. A signal can be obtained.

20, 50 Displacement detection device 21, 51 Detection object 22 Oscillation circuit 23 Signal processing unit 25a First detection coil 25b Second detection coil 25r Reference coil 31 First multiplication unit 32 Second multiplication unit 33 First low Pass-pass filter 34 Second low-pass filter 35 First gate part 36 Second gate part 37 Rectification smoothing circuit

Claims (6)

A plurality of detection circuits each having an inductance whose inductance changes in accordance with a change in relative distance to the detection object, and an oscillation frequency whose oscillation frequency depends on the inductance of the detection coil;
A signal processing unit which receives an AC predetermined electrical signal and converts the predetermined electrical signal into an electrical signal corresponding to the amount of displacement of the object to be detected based on the oscillation frequency of each oscillation circuit. A displacement detection device characterized by the above. The detection object is provided with one surface in the thickness direction facing each of the detection coils, and is angularly displaced around an axis line that is inclined with respect to the one surface,
The displacement amount detection apparatus according to claim 1, wherein at least two of the detection coils are provided at predetermined intervals around the axis. A reference coil provided at a position where the inductance is constant even when the detection object is displaced, and includes a second oscillation circuit whose oscillation frequency depends on the inductance of the reference coil;
One of the two detection coils is provided at a position where the other detection coil is angularly displaced by a predetermined angle around the axis,
The signal processing unit
A multiplier for multiplying each electrical signal oscillated by each oscillation circuit by the electrical signal oscillated by the second oscillation circuit;
Extracting the sine wave and cosine wave of the angular displacement of the detection object from the electrical signal obtained by the multiplication unit, respectively, and passing a part of the predetermined electrical signal based on the extracted sine wave and cosine wave, respectively. The displacement amount detection device according to claim 2, further comprising: a signal processing unit that outputs the signal processing unit.   The at least two coils are arranged in a predetermined direction. When the oscillation frequency of the oscillation circuit including one coil increases as the detection object is displaced in the predetermined direction, the oscillation including the other coil is performed. The displacement amount detection device according to claim 1, wherein the displacement amount detection device is provided so that an oscillation frequency of the circuit decreases. A reference coil provided at a position where the inductance is constant even when the detection object is displaced, and includes a second oscillation circuit whose oscillation frequency depends on the inductance of the reference coil;
The signal processing unit
A multiplier for multiplying the electrical signal oscillated by the oscillation circuit by the electrical signal oscillated by the second oscillation circuit;
A voltage corresponding to the increase and decrease of the oscillation frequency in each oscillation circuit is extracted from the electrical signal obtained by the multiplication unit, and a part of the predetermined electrical signal is output based on the extracted voltage. The displacement amount detection apparatus according to claim 4, further comprising a signal processing unit.   The displacement detection device according to claim 1, wherein the signal processing unit includes a power acquisition unit that rectifies a predetermined electrical signal to acquire power.

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