JP5057143B2 - Non-contact detection system - Google Patents

Description

  The present invention has a separable primary side circuit and a secondary side circuit, and wirelessly feeds power from the primary side circuit to the secondary side circuit when both the circuits are close to each other, and is provided in the secondary side circuit. The present invention relates to a non-contact detection system that wirelessly transmits a detection result by a detection unit to a primary circuit.

  A technique is known in which an AC power supply is wirelessly transmitted using a magnetically coupled primary coil and secondary coil, and information on a circuit connected to the secondary coil side is wirelessly transmitted to the primary coil side. For example, in Patent Document 1 shown below, a photocoupler is configured with a light emitting diode on the secondary coil side and a light receiving element on the primary side, and information is transferred from the secondary coil side circuit to the primary coil side circuit by optical communication. Is disclosed. Patent Document 2 shown below discloses a technique for wirelessly transmitting information superimposed on a secondary coil to the primary coil by inductive coupling. Patent Document 3 shown below discloses a technique for wirelessly transmitting power and information by capacitive coupling. Further, in Patent Document 4 shown below, in a device that performs non-contact power feeding from a power feeding coil via a power receiving coil, a technique for wirelessly transmitting information from a power receiving device to a power feeding device by radio (radio) Is disclosed.

No. 7-47957 (column 5, line 30 to column 6, line 12, FIG. 4 etc.) Japanese Patent Laying-Open No. 2005-29291 (paragraphs 32 to 34, FIG. 2, etc.) JP 2000-286760 A (19th to 32nd paragraphs, etc.) JP-A-10-2225022 (paragraphs 33-39, etc.)

  In any of the above conventional wireless transmission technologies, a control unit for transmitting information to a primary circuit or device is provided in the secondary circuit or device. For example, in Patent Document 1, an output voltage of a battery to be charged is monitored by a monitor circuit provided in a secondary circuit, and the monitor result is output as remaining amount reduction information to cause a light emitting diode to emit light. In Patent Document 2, a charge state signal is applied to a secondary coil in response to a trigger signal output from an interface controller provided in an elevator car that is a secondary device. In Patent Document 3, a communication device (not shown) is connected to a coupler that performs non-contact power supply, and a signal output from the communication device is sent to a power supply line by capacitive coupling. In Patent Document 4, the in-vehicle controller monitors the state of the immersion detection sensor of the power receiving coil, and notifies the monitoring result to the ground controller that is the primary device through the in-vehicle wireless communication device. As described above, in Patent Documents 1 to 4, control units such as a monitor circuit, an interface controller, a communication device, and an in-vehicle controller are provided in a secondary circuit or device, respectively. Therefore, these conventional techniques complicate secondary circuits and devices. For example, when constructing a sensor system in which a secondary circuit in which a sensor circuit is incorporated is contactlessly powered and the detection result of the sensor is received by wireless transmission in the primary side circuit, the sensor in which the sensor is incorporated The circuit on the next side becomes complicated.

  The invention of the present application was devised in view of the above-mentioned problems, and while supplying non-contact power from the primary side to the secondary side, the circuit configuration on the secondary side is kept small, and the information obtained on the secondary side is An object of the present invention is to provide a non-contact detection system capable of wireless transmission to a mobile phone.

In order to achieve the above object, the characteristic configuration of the non-contact detection system according to the present invention is as follows:
A separable primary side circuit and a secondary side circuit are provided, and when the two circuits are close to each other, the primary side circuit wirelessly feeds power to the secondary side circuit, and the detection unit provided in the secondary side circuit A non-contact detection system that wirelessly transmits a detection result to a primary circuit,
A transformer having a primary coil provided in the primary side circuit and a secondary coil provided in the secondary side circuit, wherein both the coils are magnetically coupled when the both circuits are close to each other, and
A detection unit provided in the secondary side circuit, the impedance of which changes due to a change in mechanical displacement or physical quantity,
The detector and connected in series or bridge connection, and the criteria unit to maintain a constant regardless of the impedance change of the mechanical displacement or a physical quantity in the secondary circuit,
A secondary side electrode provided in the secondary side circuit, to which a terminal voltage signal indicating a terminal voltage of the detection unit and the reference unit is connected in the secondary side circuit;
A primary side electrode that is provided in the primary side circuit and that forms a capacitor together with the secondary side electrode in opposition to the secondary side electrode when the two circuits are close to each other;
An impedance of the detection unit is provided based on the terminal voltage signal received through the capacitor and the impedance of the reference unit, and the mechanical displacement is determined based on the impedance of the detection unit. A computing unit for computing quantities or physical quantities;
It is in the point provided with. Or
A separable primary side circuit and a secondary side circuit are provided, and when the two circuits are close to each other, the primary side circuit wirelessly feeds power to the secondary side circuit, and the detection unit provided in the secondary side circuit A non-contact detection system that wirelessly transmits a detection result to a primary circuit,
A transformer having a primary coil provided in the primary side circuit and a secondary coil provided in the secondary side circuit, wherein both the coils are magnetically coupled when the both circuits are close to each other, and
A detection unit provided in the secondary side circuit, the impedance of which changes due to a change in mechanical displacement or physical quantity,
The secondary circuit includes a plurality of the detection units whose impedances are complementarily changed by a change in the mechanical displacement amount or physical quantity, and a combined impedance of the plurality of detection units is a change in the mechanical displacement amount or physical quantity. A reference section that maintains a constant impedance regardless of
A secondary side electrode provided in the secondary side circuit, to which a terminal voltage signal indicating a terminal voltage of the detection unit and the reference unit is connected in the secondary side circuit;
A primary side electrode that is provided in the primary side circuit and that forms a capacitor together with the secondary side electrode in opposition to the secondary side electrode when the two circuits are close to each other;
Provided in the primary side circuit, based on the terminal voltage signal received via the capacitor, the impedance of the reference unit based on the impedance of each detection unit of the plurality of detection units and the combined impedance of the detection unit, A calculation unit for calculating the mechanical displacement amount or the physical quantity by obtaining the ratio of:
It is in the point provided with.

  According to this characteristic configuration, the primary side circuit and the secondary side circuit can be separated, the detection unit is provided in the secondary side circuit, and the physical quantity that is the detection result by the detection unit is calculated by the primary side circuit. The secondary side circuit is configured by a small-scale circuit in which the detection unit and the reference unit are simply connected in series or bridged. Alternatively, the secondary side circuit includes a plurality of detection units and a plurality of detection units, and includes a small-scale circuit including a reference unit whose combined impedance is constant. The secondary side circuit does not include a circuit that generally increases in scale, such as a circuit for calculating a mechanical displacement amount or a physical amount, or a control circuit for controlling wireless transmission. A terminal voltage signal indicating terminal voltages of the detection unit and the reference unit is statically wirelessly transmitted from the secondary side circuit to the primary side circuit via the capacitor. Therefore, according to the present feature configuration, non-contact power feeding is performed from the primary side to the secondary side, the secondary side circuit configuration is kept small, and the information obtained on the secondary side is wirelessly transmitted to the primary side. It is possible to provide a non-contact detection system capable of

  In addition, the secondary circuit having the detection unit can be configured at low cost because it has a small circuit scale and does not require an internal power supply. Therefore, even if the secondary circuit is installed in many places where it is necessary to detect the mechanical displacement amount or the physical quantity, the total installation cost can be suppressed. The primary side circuit is more complex than the secondary side circuit and requires a power source, and is therefore more expensive than the secondary side circuit. However, if one primary side circuit is sequentially brought close to the secondary side circuit installed in many places, the mechanical displacement amount or physical quantity detected by each secondary side circuit can be obtained sequentially. it can. Therefore, it is possible to realize a non-contact detection system capable of acquiring a lot of information while suppressing the total cost.

  Further, according to a further characteristic configuration of the non-contact detection system according to the present invention, the calculation unit has a differential calculation unit, and calculates a voltage between the terminals of the detection unit and the reference unit based on the terminal voltage signal. The ratio of the impedance of the detection unit and the reference unit is obtained based on the voltage between the terminals.

  The detection unit and the reference unit are connected in series or bridge. The series connection and the bridge connection are circuit configurations in which it is easy to grasp the magnitude and ratio of the current flowing through the circuit. According to this characteristic configuration, the voltage between the terminals of each detection unit and each reference unit is calculated based on the terminal voltage signal. Since the current can be easily grasped as described above, the impedance ratio between the detection unit and the reference unit can be favorably obtained using Ohm's law based on the voltage between the terminals.

  Further, the non-contact detection system according to the present invention is further characterized in that an effective electrode area of the primary side electrode and the secondary side electrode constituting the capacitor when the primary side circuit and the secondary side circuit are close to each other is The distance between the primary side electrode and the secondary side electrode constituting each capacitor is in an equal ratio.

  When the effective electrode area of each capacitor is equivalent, the capacitance of the capacitor is inversely proportional to the interelectrode distance between the primary electrode and the secondary electrode. In other words, the capacitance ratio of the capacitors can be kept constant by keeping the distance between the electrodes of each capacitor constant. Since the distance between the electrodes is known from the structure of the system, that is, the structure when the primary side circuit and the secondary side circuit are close to each other, the proportionality coefficient of each capacitor is also known. The proportional coefficient of the capacitor is a proportional coefficient of each terminal voltage signal transmitted through each capacitor. Therefore, if the proportionality factor of the capacitor is constant, the voltage value of the terminal voltage signal in the secondary circuit can be accurately reproduced in the calculation unit.

  Further, in the non-contact detection system according to the present invention, as described above, when the effective electrode area of each electrode of the capacitor is equivalent, and the distance between the electrodes in each capacitor is in an equal relationship, The distance between the electrodes, which is the relationship of

  If the distance between the electrodes is equal, the capacitances of all capacitors in the system are equivalent. The terminal voltage signal transmitted through the capacitor is transmitted at the same rate of change (amplification rate or attenuation rate). Therefore, the voltage value of the terminal voltage signal in the secondary circuit can be more accurately reproduced in the calculation unit.

  The characteristic configuration of the non-contact detection system according to the present invention is that the detection unit is configured to include a thermal resistance.

  A thermal resistance, for example, a thermistor, changes its resistance value, ie, impedance, which is a circuit constant as a passive element, depending on the temperature as a physical quantity. Therefore, it can be used as a detection unit for detecting temperature. For example, by installing the secondary circuit inside the device, the secondary coil and the secondary electrode facing the exterior side, and bringing the primary circuit close from the outside of the device exterior, the inside of the device The temperature can be detected from the outside of the device. That is, it is possible to obtain a preferred embodiment of the present invention by configuring the detection unit including a thermal resistor.

  Another feature of the non-contact detection system according to the present invention is that the detection unit includes any one of a potentiometer, a variable resistor, a variable capacitor, and a variable inductance.

  Potentiometers, variable resistors, variable capacitors, and variable inductances vary mainly in circuit constants as passive elements, such as resistance values, capacitances, and inductances, depending on the amount of mechanical displacement or physical quantity, and the impedance changes. Therefore, it is suitable as the detection unit of the present invention. It becomes possible to obtain a preferred embodiment of the present invention by configuring the detection unit to include any of these.

[First Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a circuit block diagram schematically showing a configuration example of a non-contact detection system according to a first embodiment of the present invention. The primary side circuit 1 and the secondary side circuit 2 are stored in different housings (not shown), and are configured to be separable and close to each other. The housings of the primary side circuit 1 and the secondary side circuit 2 include, for example, fitting portions that are fitted to each other and suction portions that are externally attracted by magnetic force. Since the circuit itself is stored in both housings, the primary side circuit 1 and the secondary side circuit 2 are relatively positioned and in a close proximity state in a state where both housings are fitted or adsorbed. It becomes. Moreover, when both housing | casings cancel a fitting state and an adsorption | suction state, the primary side circuit 1 and the secondary side circuit 2 will be in a separation state.

  The primary circuit 1 includes a primary coil 31, and the secondary circuit 2 includes a secondary coil 32. When the primary side circuit 1 and the secondary side circuit 2 are relatively positioned and are in the proximity state, the primary coil 31 and the secondary coil 32 are magnetically coupled to constitute the transformer 3. Accordingly, when the primary side circuit 1 and the secondary side circuit 2 are in the proximity state, wireless power feeding from the primary side circuit 1 to the secondary side circuit 2 is possible. The primary circuit 1 includes an AC power supply 10, and the AC power supply 10 is connected to the primary coil 31 and supplies power to the primary coil. In order to reduce the exciting current of the primary coil 31, the AC power supply 10 supplies the primary coil 31 with power of several k to 100 kHz, which is a higher frequency than the commercial frequency of 50 to 60 Hz. The transformer 3 causes the secondary coil 32 to generate a voltage corresponding to the voltage applied to the primary coil 31. The transformer 3 is preferably configured to have a split core made of a magnetic material. In the transformer 3 with this configuration, the primary coil 31 and the secondary coil 32 can be separated, and the exciting current of the primary coil 31 can be reduced. A load 20 is connected to the output of the secondary coil 32 as necessary.

  The secondary circuit 2 includes a detection unit 5 that detects a mechanical displacement amount such as a position and an angle, and a physical amount such as a temperature. The detection unit 5 is an element whose impedance changes due to a change in mechanical displacement or physical quantity. For example, the detection unit 5 includes a thermistor whose resistance changes with a change in temperature, a potentiometer whose resistance changes with a change in angle, and the like. In the present embodiment, an example in which the detection unit 5 is configured by such a variable impedance element 51 is shown. Then, the detection result by the detection unit 5 is wirelessly transmitted to the primary circuit 1. That is, the non-contact detection system of the present embodiment wirelessly feeds power from the primary side circuit 1 to the secondary side circuit 2 when the separable primary side circuit 1 and secondary side circuit 2 are close to each other, and the secondary side circuit 2. This is a system for wirelessly transmitting the detection result by the detection unit 5 provided to the primary side circuit 1.

  The secondary circuit 2 includes a reference unit 6 that is connected in series with the detection unit 5 and maintains a constant impedance regardless of changes in mechanical displacement or physical quantity. The reference unit 6 is configured by a resistor having a fixed resistance value, such as a resistor. In particular, when the physical quantity to be detected is temperature, it is preferable to use a resistor whose resistance value changes little due to temperature change, that is, a resistor with good temperature characteristics. In the present embodiment, an example is shown in which the two reference portions 6 are composed of fixed impedance elements 61 and 62 such as fixed resistors.

  In the present embodiment, as shown in FIG. 1, a series circuit including one variable impedance element 51 and two fixed impedance elements 61 and 62 is connected to the output of the secondary coil 32. Specifically, one end of the variable impedance element 51 is connected to one end of the output of the secondary coil 32, and the other end of the variable impedance element 51 is connected to one end of the first fixed impedance element 61. The other end of the first fixed impedance element 61 is connected to one end of the second fixed impedance element 62. The other end of the second fixed impedance element 62 is connected to the other end of the secondary coil 32. In the present embodiment, an example is shown in which a circuit composed of the detection unit 5 and the reference unit 6 is directly connected to the output of the secondary coil 32, but in a form in which the circuit is connected via a rectifier circuit to direct current. There may be. The same applies to the second and subsequent embodiments to be described later.

  It is assumed that the variable impedance element 51 has an impedance of Z0 (Ω), the first fixed impedance element 61 has an impedance of Z1 (Ω), and the second fixed impedance element 62 has an impedance of Z2 (Ω). The impedance Z0 of the variable impedance element 51 is a value that changes according to the mechanical displacement amount or the physical amount.

  Further, the secondary side circuit 2 includes secondary side electrodes 42 to which terminal voltage signals indicating terminal voltages of the detection unit 5 and the reference unit 6 in the secondary side circuit 2 are respectively connected. Each secondary-side electrode 42 is provided in the primary-side circuit 1 to form a capacitor 4 together with each primary-side electrode 41 that faces each secondary-side electrode 42 when the primary-side circuit 1 and the secondary-side circuit 2 are close to each other. To do. That is, the capacitor 4 is formed between the adjacent primary side circuit 1 and the secondary side circuit 2. A terminal voltage signal is wirelessly transmitted from the secondary side circuit 2 to the primary side circuit 1 through these capacitors 4.

  As shown in FIG. 1, in this embodiment, the voltage at both ends of the variable impedance element 51 and the voltage at both ends of the fixed impedance element 61 are respectively input to the secondary electrode 42. The variable impedance element 51 and the fixed impedance element 61 are connected by one terminal. Therefore, in the present embodiment, three voltages, ie, two voltages of the other terminal of both elements 51 and 61 and one voltage of one terminal to which both elements 51 and 61 are connected are three two voltages. Input to the secondary electrodes 42a, 42b, 42c.

  As described above, the capacitor 4 is formed when the primary circuit 1 and the secondary circuit 2 are close to each other. The primary side circuit 1 is provided with primary side electrodes 41a, 41b, and 41c facing the secondary side electrodes 42a, 42b, and 43c, respectively. That is, when the primary side circuit 1 and the secondary side circuit 2 are close to each other, 3 of the capacitors 4a, 4b, and 4c formed by the primary side electrodes 41a, 41b, and 41c and the secondary side electrodes 42a, 42b, and 42c. Two capacitors are formed. The three voltages described above are wirelessly transmitted to the primary circuit 1 through the capacitors 4 (4a, 4b, 4c) as terminal voltage signals. The impedance of the capacitor 4 is sufficiently larger than the elements 51 and 61 constituting the detection unit 5 and the reference unit 6, and the current flowing through the capacitor 4 is sufficiently smaller than the current flowing through the elements 51 and 61. Therefore, the current flowing through the series circuit composed of the detection unit 5 and the reference unit 6 is not affected by the capacitor 4, and a terminal voltage signal corresponding to the impedance of the detection unit 5 and the reference unit 6 is input to the capacitor 4. The

  The terminal voltage signal received via the capacitor 4 is input to the arithmetic unit 7 provided in the primary side circuit 1. The calculation unit 7 is a functional unit that calculates the physical quantity detected by the detection unit 5 by obtaining the impedance ratio of the detection unit 5 and the reference unit 6 based on the terminal voltage signal. In the present embodiment, the calculation unit 7 includes a buffer amplifier 11, a differential amplifier 12 (differential calculation unit), and a microprocessor (MPU) 13.

  In addition, when the capacitor 4 is formed when the primary side circuit 1 and the secondary side circuit 2 are close to each other, it is preferable that the interelectrode distances between the primary side electrodes 41 and the secondary side electrodes 42 are equal distances. It is. Here, consider the capacitances Ca, Cb, and Cc of the capacitors 4a, 4b, and 4c when the primary side electrode 41 and the secondary side electrode 42 of the capacitor 4 face each other substantially in parallel. The effective electrode areas of the capacitors 4a, 4b, and 4c are Sa, Sb, and Sc, and the interelectrode distances between the primary electrodes 41a, 41b, and 41c and the secondary electrodes 42a, 42b, and 42c are La and Lb, respectively. , Lc. Capacitances Ca, Cb, and Cc of the capacitors 4a, 4b, and 4c are expressed by the following formulas (1) to (3).

Ca ∝ Sa / La (1)
Cb ∝ Sb / Lb (2)
Cc ∝ Sc / Lc (3)

  If the effective electrode area of each capacitor 4 is substantially equal, the capacitance ratio Ca: Cb: Cc of each capacitor 4 is made constant by keeping the ratio La: Lb: Lc between the electrodes of each capacitor 4 constant. Can do. Of course, if the interelectrode distances La, Lb, Lc of each capacitor 4 are substantially equal, the capacitances Ca, Cb, Cc of each capacitor 4 are substantially equal. If the capacitances Ca, Cb, and Cc of the capacitor 4 are approximately equal, the rate of change (attenuation rate, etc.) due to transmission of each terminal voltage signal is constant. Therefore, it is preferable that the calculation accuracy of the calculation unit 7 can be maintained at a high level. However, when the distance between all the electrodes cannot be made constant because of the structure, it is preferable to make the ratio of the distance between the electrodes constant. The terminal voltage signal input to the calculation unit 7 can be corrected by the calculation unit 7 according to the ratio, but the calculation load caused by the calculation unit 7 during correction can be suppressed.

  The terminal voltage signal input to the calculation unit 7 via the capacitor 4 is a signal having a high output impedance. Therefore, when the input impedance of the arithmetic unit 7 is low impedance, the terminal voltage signal is greatly attenuated. Therefore, the arithmetic unit 7 is provided with a buffer amplifier 11 (11a, 11b, 11c) that receives a terminal voltage signal input via the capacitors 4a, 4b, 4c. Since the buffer amplifier 11 has a very high input impedance, it can receive the terminal voltage signal without attenuating the signal at the entrance of the arithmetic unit 7. Further, the buffer amplifier 11 can flow a large amount of output current, and converts the terminal voltage signal into a low impedance signal. Therefore, even when the input impedance of the circuit subsequent to the arithmetic unit 7 is low, the power of the terminal voltage signal can be increased so that the circuit can be sufficiently operated. Thus, the buffer amplifier 11 functions as an impedance converter.

  In this embodiment, the buffer amplifier 11 is composed of an operational amplifier. Each output of the buffer amplifier 11 (11 a to 11 c) is proportional to the potential difference between the terminal voltage signal input to the capacitor 4 and the reference voltage Vref of the buffer amplifier 11 in the output frequency band of the AC power supply 10. The proportionality constants are substantially equal to each other including the phase in each of the three signals.

  2 to 4 are circuit block diagrams schematically showing a specific configuration example of the buffer amplifier 11. FIG. 2 is a circuit block diagram showing a first configuration example. The resistance value and the capacitance value of the feedback resistor R1 and the feedback capacitor C1 of the operational amplifier 11A in FIG. 2 are set so that the following expression (4) is established with respect to the output frequency f of the AC power supply 10.

  f >> 1 / (2πR1C1) (4)

  Here, when the capacitance of the capacitor 4 is Cin and the terminal voltage of the secondary electrode 42 of the capacitor 4 is Vin, the output Vout of the buffer amplifier 11 shown in FIG. 2 is sufficiently higher than the right side of the equation (4). In the frequency band, the following equation (5) is obtained.

  Vout = − {(Vin −Vref) × Cin / C1} + Vref (5)

  FIG. 3 is a circuit block diagram showing a second configuration example. The output Vout of the buffer amplifier 11 shown in FIG. 3 is a function of the output frequency f of the AC power supply 10, and is expressed by the following equation (6).

  Vout = − {(Vin −Vref) × 2πf × Cin × R2} + Vref (6)

  FIG. 4 is a circuit block diagram showing a third configuration example. The resistance value of the resistor R5 in FIG. 4 is set so that the following expression (7) is established with respect to the output frequency f of the AC power supply 10 and the capacitance Cin of the capacitor 4.

  f >> 1 / (2πR5 × Cin) (7)

  Here, when the capacitance of the capacitor 4 is Cin and the terminal voltage of the secondary electrode 42 of the capacitor 4 is Vin, the output Vout of the buffer amplifier 11 shown in FIG. 4 is sufficiently higher than the right side of the equation (7). In the frequency band, the following equation (8) is obtained.

  Vout = {(Vin – Vref) × (R3 + R4) / R4} + Vref (8)

  The outputs of the three buffer amplifiers 11 (11a, 11b, 11c) are input to the two differential amplifiers 12 (12a, 12b). Since the output of the buffer amplifier 11b is a terminal voltage signal common to the variable impedance element 51 and the fixed impedance element 61, it is input to both of the two differential amplifiers 12a and 12b. The outputs of the buffer amplifiers 11a and 11c are terminal voltage signals that are different between the variable impedance element 51 and the fixed impedance element 61, respectively. Accordingly, the signals are individually input to the differential amplifiers 12a and 12b. Thus, the two differential amplifiers 12a and 12b calculate the voltage across the terminals of the variable impedance element 51 and the voltage across the terminals of the fixed impedance element 61, respectively. The amplification factors of the two differential amplifiers 12a and 12b are substantially equal including the phase.

  The ratio (= V1 / V0) between the output V1 of the differential amplifier 12b and the output V0 of the differential amplifier 12a is the ratio of the voltage applied to the fixed impedance element 61 and the voltage applied to the variable impedance element 51. Almost equal. The fixed impedance element 61 and the variable impedance element 51 are connected in series, and substantially the same current flows. Accordingly, the impedance ratio between the fixed impedance element 61 and the variable impedance element 51 is substantially equal to the ratio between the outputs V1 and V0 of the differential amplifier 12. Accordingly, the impedance Z0 (resistance value) of the variable impedance element 51 is obtained by the following equation (9).

  Z0 = Z1 x (V0 / V1) (9)

  Here, when the elements 51 and 61 are elements including not only resistors but also capacitors and coils, the impedances Z0 and Z1 are complex impedances. If the phase difference between the outputs V0 and V1 of the differential amplifier 12 is measured and Z1 is known as the complex impedance, Z0 can also be obtained as the complex impedance as described above. As described above, the magnitude of the impedance Z0 of the variable impedance element 51 varies depending on the physical quantity. Therefore, the physical quantity can be obtained from the magnitude of the impedance Z0. As is clear from equation (9), the impedance Z2 of the second fixed impedance element 62 is not necessarily known and may be 0Ω.

  The MPU 13 executes the calculation of the output ratio of the differential amplifier 12, the impedance Z0, and the physical quantity. The outputs V0 and V1 of the differential amplifier 12 are input to the MPU 13. The MPU 13 incorporates an A / D converter (not shown) and converts the input outputs V0 and V1 of the differential amplifier 12 into digital values suitable for digital calculation. Further, the MPU 13 stores the values of the impedances Z1 and Z2 of the fixed impedance elements 61 and 62 whose impedance is known in a storage unit (not shown). This storage unit is preferably composed of a rewritable and non-volatile memory. For example, a flash memory built in the MPU 13 can be used. The MPU 13 calculates the impedance Z0 of the variable impedance element 51 based on the outputs V0 and V1 of the differential amplifier 12 converted into digital values and the impedance Z1 of the fixed impedance element 61.

  In addition, the storage unit stores a correspondence table and a correspondence expression indicating a relative relationship between the impedance Z0 of the variable impedance element 51 and the mechanical displacement amount or the physical amount. The MPU 13 calculates a mechanical displacement amount or a physical amount based on these correspondence tables and correspondence expressions and the calculated impedance Z0.

  In the present embodiment, the configuration using the differential amplifier 12 as the differential operation unit is exemplified, but the present invention is not limited to this. The output of the buffer amplifier 11 may be input to the MPU 13 and A / D converted by the MPU 13, and then the terminal voltage may be calculated by digital calculation. In this case, the MPU 13 functions as a differential operation unit.

  Note that a filter (not shown) that passes the frequency band of the output of the AC power supply 10 may be provided between the buffer amplifier 11 and the differential amplifier 12 or between the differential amplifier 12 and the MPU 13.

  As described above, the primary side circuit 1 and the secondary side circuit 2 can be separated, and the detection unit 5 is provided in the secondary side circuit 2, and the mechanical displacement amount or physical quantity as a detection result is the primary side. Calculation is performed by the circuit 1. The secondary-side circuit 2 is composed of a small-scale circuit exclusively composed of elements corresponding to the detection unit 5 and the reference unit 6, and does not include a large-scale circuit that calculates a mechanical displacement amount or a physical amount. Therefore, according to the present embodiment, non-contact power feeding is performed from the primary side to the secondary side, the circuit configuration on the secondary side is kept small, and information obtained on the secondary side is wirelessly transmitted to the primary side. It is possible to provide a non-contact detection system capable of

  Since the secondary circuit 2 having the detection unit 5 has a small circuit scale and does not require a power source, it can be configured at low cost. Therefore, the installation cost can be suppressed even if the secondary circuit 2 is installed at a number of locations where it is desired to detect the mechanical displacement amount or the physical quantity. The primary side circuit 1 is more complicated than the secondary side circuit 2 and requires a power source, so that it is more expensive than the secondary side circuit 2. However, if one primary side circuit 1 is sequentially brought close to a plurality of secondary side circuits 2 installed, the mechanical displacement amount or physical quantity detected by the secondary side circuit 2 can be obtained sequentially. . Therefore, it is possible to realize a non-contact detection system that can acquire a large amount of information while suppressing the total cost.

  As an example, the secondary side circuit 2 provided with the detection part 5 which can detect temperature in the several places of an apparatus is installed. The secondary circuit 2 is installed inside the device with the secondary coil 32 and the secondary electrode 42 facing the exterior side. By bringing the primary circuit 1 close to the plurality of locations where the secondary circuit 2 is installed from the outside of the exterior of the device, it becomes possible to obtain temperature information inside the device from the outside of the device. . In other words, by applying the non-contact detection system of the present invention, it is possible to construct an inspection system or the like for checking the temperature rise of the device.

[Second Embodiment]
FIG. 5 is a circuit block diagram schematically illustrating a configuration example of the non-contact detection system according to the second embodiment. Since the circuit configuration excluding the configuration of the calculation unit 7 is the same as that of the first embodiment, the description thereof is omitted. In the calculation unit 7 of the second embodiment, the case where the proportional constants of the buffer amplifier 11 are not substantially equal to each other including the phase in each of the three terminal voltage signals is illustrated. In order to adjust the difference in proportionality constant, in the second embodiment, a potentiometer 14 (14a, 14b, 14c) is provided between the buffer amplifier 11 and the differential amplifier 12. The potentiometer 14 is configured such that the ratio between the terminal voltage signal connected to the secondary electrode 42 and the reference voltage Vref and the ratio between the voltage input to the differential amplifier 12 and the reference voltage Vref are equal. It is an adjustment mechanism to adjust. Through this adjustment mechanism, the MPU 13 calculates the impedance Z0 of the variable impedance element 51 as in the first embodiment. Then, the MPU 13 calculates the mechanical displacement amount or the physical amount detected by the variable impedance element 51 functioning as the detection unit 5 based on the impedance Z0. As in the first embodiment, the impedance Z2 of the second fixed impedance element 62 is not necessarily known, and may be 0Ω.

[Third Embodiment]
FIG. 6 is a circuit block diagram schematically illustrating a configuration example of the non-contact detection system according to the third embodiment. The third embodiment is different from the first embodiment in that the circuit configuration connected to the secondary coil 32, that is, the circuit configured by the detection unit 5 and the reference unit 6 is different. Accordingly, the connection between the buffer amplifier 11 and the differential amplifier 12 of the arithmetic unit 7 is also partially different. About another structure, it is the same as that of 1st Embodiment.

  In the present embodiment, as shown in FIG. 6, a bridge circuit including one variable impedance element 51 and three fixed impedance elements 61, 62, 63 is connected to the output of the secondary coil 32. Specifically, one end of the variable impedance element 51 is connected to one end of the output of the secondary coil 32, and the other end of the variable impedance element 51 is connected to one end of the first fixed impedance element 61. The other end of the first fixed impedance element 61 is connected to the other end of the secondary coil 32. One end of the output of the secondary coil 32 to which one end of the variable impedance element 51 is connected is further connected to one end of the second fixed impedance element 62, and the other end of the second fixed impedance element 62 is the third fixed. It is connected to one end of the impedance element 63. The other end of the third fixed impedance element 63 is connected to the other end of the secondary coil 32 together with the other end of the first fixed impedance element 61. It is assumed that the first fixed impedance element 61 has an impedance of Z1 (Ω), the second fixed impedance element 62 has an impedance of Z3 (Ω), and the third fixed impedance element 63 has an impedance of Z4 (Ω). The variable impedance element 51 has an impedance of Z0 (Ω), which is a value that changes according to a mechanical displacement amount or a physical amount.

  As in the first embodiment, the terminal voltage signal of the bridge circuit of the secondary circuit 2 is input to the arithmetic unit 7 via the capacitor 4. In the third embodiment, a terminal voltage signal capable of calculating the voltage between the terminals of the variable impedance element 51 and the voltage between the terminals of the second fixed impedance element 62 is input to the calculation unit 7. The differential amplifier 12 calculates a voltage V0 corresponding to the voltage between the terminals of the variable impedance element 51 and a voltage V2 corresponding to the voltage between the terminals of the second fixed impedance element 62. Based on these voltages V0, V2 and known impedances Z1, Z3, Z4, the MPU 13 obtains a variable impedance Z0 by the following equation (10).

  Z0 = (V0 × Z3 × Z1) / {(V2 × Z3) + (V2 × Z4) − (V0 × Z3)} (10)

[Fourth Embodiment]
FIG. 7 is a circuit block diagram schematically showing a configuration example of the non-contact detection system of the fourth embodiment. The fourth embodiment is different from the first embodiment in that the first fixed impedance element 61 of the first embodiment is a second variable impedance element 52. Other configurations are the same as those in the first embodiment. The variable impedance element 51 is referred to as a first variable impedance element 51 in the present embodiment. The first variable impedance element 51 and the second variable impedance element 52 function as the detection unit 5 of the present invention. The first variable impedance element 51 has an impedance of Z01 (Ω), and the second variable impedance element 52 has an impedance of Z02 (Ω). These are values that change according to the mechanical displacement or physical quantity, respectively, but the sum of both impedances Z01 and Z02 is a constant known value. That is, the impedances Z01 and Z02 are variable impedances whose values complementarily change according to the mechanical displacement amount or the physical amount. Further, both impedances Z01 and Z02 constitute a reference unit 6 of the present invention because the combined impedance maintains a constant impedance regardless of changes in mechanical displacement or physical quantity. If the sum of the variable impedances Z01 and Z02 is Z5, the variable impedance Z01 can be obtained by the following equation (11).

  Z01 = V0 × Z5 / (V1 + V0) (11)

  As is clear from equation (11), as in the first embodiment, the impedance Z2 of the second fixed impedance element 62 is not necessarily known and may be 0Ω. In the fourth embodiment, the combined impedance of the series circuit of the two impedances Z01 and Z02 is constant, and the reference unit is configured by the impedances Z01 and Z02. However, the present invention is not limited to this example, and the reference unit may be constituted by three or more variable impedances.

[Fifth Embodiment]
FIG. 8 is a circuit block diagram schematically showing a configuration example of the non-contact detection system of the fifth embodiment. The fifth embodiment is different from the first embodiment in that the circuit configuration connected to the secondary coil 32, that is, the circuit configured by the detection unit 5 and the reference unit 6 is different. Accordingly, the number of components of the capacitor 4 and the buffer amplifier 11 of the arithmetic unit 7 and the connection between the buffer amplifier 11 and the differential amplifier 12 are partially different. About another structure, it is the same as that of 1st Embodiment.

  In the present embodiment, as shown in FIG. 6, a bridge circuit including two variable impedance elements 51 and 52 and two fixed impedance elements 61 and 63 is connected to the output of the secondary coil 32. Specifically, one end of the first variable impedance element 51 is connected to one end of the output of the secondary coil 32, and the other end of the variable impedance element 51 is connected to one end of the first fixed impedance element 61. The other end of the first fixed impedance element 61 is connected to the other end of the secondary coil 32 via the second fixed impedance element 62. One end of the output of the secondary coil 32 to which one end of the variable impedance element 51 is connected is further connected to one end of the third fixed impedance element 63, and the other end of the third fixed impedance element 63 is the second variable. It is connected to one end of the impedance element 52. The other end of the second variable impedance element 52 is connected to the other end of the secondary coil 32 through the second fixed impedance element 62 together with the other end of the first fixed impedance element 61.

  Here, it is assumed that the first fixed impedance element 61 has an impedance of Z1 (Ω), the second fixed impedance element 62 has an impedance of Z2 (Ω), and the third fixed impedance element 63 has an impedance of Z3 (Ω). The first variable impedance element 51 has an impedance of Z01 (Ω), and the second variable impedance element 52 has an impedance of Z02 (Ω). The impedances Z01 and Z02 are values that change according to the mechanical displacement amount or the physical amount. It is assumed that the ratio between the fixed impedance Z1 and the variable impedance Z01 is equal to the ratio between the fixed impedance Z3 and the variable impedance Z02. As in the first embodiment, the impedance Z2 of the second fixed impedance element 62 is not necessarily known, and may be 0Ω.

  In the present embodiment, four capacitors 4 (4a, 4b, 4c, 4d) are formed between the primary side circuit 1 and the secondary side circuit 2. As shown in FIG. 8, the secondary circuit 2 has a bridge circuit configuration including four elements of fixed impedance elements 61 and 62 and variable impedance elements 51 and 52 on each side of a square. To each secondary electrode 42 of the capacitor 4, the voltage between the elements in the bridge circuit, that is, the voltages at the four vertexes of the square is input as a terminal voltage signal. The four terminal voltage signals are wirelessly transmitted to the arithmetic unit 7 of the primary circuit 1 through the capacitor 4 and input to the buffer amplifier 11 (11a, 11b, 11c, 11d) of the arithmetic unit 7.

  The proportionality constant of the buffer amplifier 11 is set to be substantially equal in each system in the combination of the system of the buffer amplifiers 11a and 11d and the system of the buffer amplifiers 11b and 11c. Further, the buffer amplifiers 11 are set so that the phase shifts are almost equal in the system of all the buffer amplifiers 11. The outputs of the buffer amplifiers 11a and 11d and the outputs of the buffer amplifiers 11b and 11c are input to the differential amplifiers 12a and 12b, respectively.

Here, the ratio between the potential difference between the secondary side electrodes 42a and 42d of the capacitor 4 and the output V3 of the differential amplifier 12a after differentially amplifying the voltages of the secondary side electrodes 42a and 42d in the primary side circuit 1 ^Is G0 (= | G0 | e ^(jθ0) ). Further, the ratio between the potential difference between the secondary side electrodes 42a and 42d of the capacitor 4 and the output V4 of the differential amplifier 12b after differentially amplifying the voltages of the secondary side electrodes 42b and 42c in the primary side circuit 1 is expressed as follows. ^Let G2 (= | G2 | e ^(jθ2) ). As described above, when the ratio between the fixed impedance Z1 and the variable impedance Z01 is equal to the ratio between the fixed impedance Z3 and the variable impedance Z02, the variable impedances Z01 and Z02 are calculated by the following equations (12) and (13). The

Z01 = (V3G2−V4G0) / (V3G2 + V4G0) × Z1 (12)
Z02 = (V3G2−V4G0) / (V3G2 + V4G0) × Z3 (13)

[Sixth Embodiment]
FIG. 9 is a block diagram schematically showing an application example of the non-contact detection system of the present invention. Here, an example in which the non-contact detection system according to the first embodiment is applied to a drive system of a three-phase AC motor (motor) 9 is shown. In the present embodiment, the AC power supply 10 is a three-phase AC power supply device 15, and the transformer 3 is a three-phase transformer 3A. The motor 9 is driven by a three-phase alternating current of U, V, and W phases applied to the motor 9 via the three-phase transformer 3A. A sensor 8 that detects the rotor position of the motor 9 and the displacement of the mechanism driven by the motor 9 is provided in the vicinity of the motor 9. The sensor 8 is, for example, a potentiometer, a variable resistor, an angle sensor, or the like. The sensor 8 corresponds to the detection unit 5 of the present invention, and corresponds to the variable impedance element 51 of the first embodiment described above.

  The mechanical displacement amount detected by the sensor 8, that is, the rotor position and the displacement of the mechanism are calculated by the calculation unit 7 as described above. In the present embodiment, the calculation unit 7 also functions as a control unit that controls the motor 9 and the three-phase AC power supply device 15. Accordingly, the calculation unit 7 feedback-controls the motor 9 and the three-phase AC power supply device 15 based on the calculated mechanical displacement amount. In this embodiment, the case where the sensor 8 which detects the rotor position of the motor 9 and the displacement of the mechanism driven by the motor 9 is provided was illustrated. However, the present invention is not limited to this, and the sensor 8 may be configured to detect the temperature of the motor 9 or a mechanism driven by the motor 9. In this case, the sensor 8 is composed of a thermistor (thermal resistance) or the like.

[Other Embodiments]
The detection unit 5 is preferably configured to include any one of a variable resistor, a variable capacitor, and a variable inductance in addition to a potentiometer and a thermistor. That is, the detection unit 5 can be configured to include various elements whose circuit constants mainly change as passive elements and whose impedance changes. Therefore, those skilled in the art will easily understand that modifications can be made as appropriate without departing from the spirit of the present invention. However, such other embodiments modified without departing from the spirit of the present invention are also included in the present invention.

  As described above, according to the present invention, non-contact power feeding is performed from the primary side to the secondary side, the circuit configuration on the secondary side is kept small, and the information obtained on the secondary side is wirelessly transmitted to the primary side. It is possible to provide a non-contact detection system that can be used.

A circuit block diagram schematically showing a configuration example of the non-contact detection system of the first embodiment. Circuit block diagram schematically showing a specific configuration example 1 of the buffer amplifier Circuit block diagram schematically showing a specific configuration example 2 of the buffer amplifier Circuit block diagram schematically showing a specific configuration example 3 of the buffer amplifier Circuit block diagram schematically showing a configuration example of the non-contact detection system of the second embodiment Circuit block diagram schematically showing a configuration example of the non-contact detection system of the third embodiment Circuit block diagram schematically showing a configuration example of the non-contact detection system of the fourth embodiment Circuit block diagram schematically showing a configuration example of the non-contact detection system of the fifth embodiment The block diagram which shows the example of application of the non-contact detection system of this invention typically

Explanation of symbols

1: Primary circuit 2: Secondary circuit 3: Transformer 31: Primary coil 32: Secondary coils 4, 4a, 4b, 4c, 4d: Capacitors 41, 41a, 41b, 41c, 41d: Primary electrodes 42, 42a , 42b, 42c, 42c: secondary side electrodes 5, 51, 52: variable impedance element (detection unit)
6, 61, 62, 63: Fixed impedance element (reference part)
7: Calculation unit 8: Sensor (detection unit)
9: three-phase AC motor 10: AC power supply 21, 21A, 21B: variable impedance element (detection unit)
22, 23: Fixed impedance element (reference part)
15: 3-phase AC power supply (AC power supply)

Claims (7)

A separable primary side circuit and a secondary side circuit are provided, and when the two circuits are close to each other, the primary side circuit wirelessly feeds power to the secondary side circuit, and the detection unit provided in the secondary side circuit A non-contact detection system that wirelessly transmits a detection result to a primary circuit,
A transformer having a primary coil provided in the primary side circuit and a secondary coil provided in the secondary side circuit, wherein both the coils are magnetically coupled when the both circuits are close to each other, and
A detection unit provided in the secondary side circuit, the impedance of which changes due to a change in mechanical displacement or physical quantity,
The detector and connected in series or bridge connection, and the criteria unit to maintain a constant regardless of the impedance change of the mechanical displacement or a physical quantity in the secondary circuit,
A secondary side electrode provided in the secondary side circuit, to which a terminal voltage signal indicating a terminal voltage of the detection unit and the reference unit is connected in the secondary side circuit;
A primary side electrode that is provided in the primary side circuit and that forms a capacitor together with the secondary side electrode in opposition to the secondary side electrode when the two circuits are close to each other;
An impedance of the detection unit is provided based on the terminal voltage signal received through the capacitor and the impedance of the reference unit, and the mechanical displacement is determined based on the impedance of the detection unit. A computing unit for computing quantities or physical quantities;
A non-contact detection system comprising: A separable primary side circuit and a secondary side circuit are provided, and when the two circuits are close to each other, the primary side circuit wirelessly feeds power to the secondary side circuit, and the detection unit provided in the secondary side circuit A non-contact detection system that wirelessly transmits a detection result to a primary circuit,
A transformer having a primary coil provided in the primary side circuit and a secondary coil provided in the secondary side circuit, wherein both the coils are magnetically coupled when the both circuits are close to each other, and
A detection unit provided in the secondary side circuit, the impedance of which changes due to a change in mechanical displacement or physical quantity,
The secondary circuit includes a plurality of the detection units whose impedances are complementarily changed by a change in the mechanical displacement amount or physical quantity, and a combined impedance of the plurality of detection units is a change in the mechanical displacement amount or physical quantity. A reference section that maintains a constant impedance regardless of
A secondary side electrode provided in the secondary side circuit, to which a terminal voltage signal indicating a terminal voltage of the detection unit and the reference unit is connected in the secondary side circuit;
A primary side electrode that is provided in the primary side circuit and that forms a capacitor together with the secondary side electrode in opposition to the secondary side electrode when the two circuits are close to each other;
Provided in the primary side circuit, based on the terminal voltage signal received via the capacitor, the impedance of the reference unit based on the impedance of each detection unit of the plurality of detection units and the combined impedance of the detection unit, A calculation unit for calculating the mechanical displacement amount or the physical quantity by obtaining the ratio of:
A non-contact detection system comprising: The calculation unit includes a differential calculation unit, calculates a voltage between the detection unit and the reference unit based on the terminal voltage signal, and calculates the detection unit and the reference unit based on the terminal voltage. The non-contact detection system according to claim 1 or 2 , wherein an impedance ratio is obtained. When the primary side circuit and the secondary side circuit are close to each other, effective electrode areas of the primary side electrode and the secondary side electrode that constitute the capacitor are equivalent, and the primary side electrode that constitutes each capacitor and the second side electrode are equivalent to each other. The non-contact detection system according to any one of claims 1 to 3 , wherein an inter-electrode distance with the secondary electrode has an equal ratio. 5. The non-contact detection system according to claim 4 , wherein the inter-electrode distances having an equiratio relationship are equidistances having an equivalence coefficient of 1. 5. The non-contact detection system according to any one of claims 1 to 5 , wherein the detection unit includes a thermal resistor. Wherein the detection unit includes a potentiometer, variable resistor, a non-contact detection system according to any one of constituted claims 1-5 including a variable capacitor, one of the variable inductance

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