TW201326805A - Non-contact measurement device with adjustable range - Google Patents

Abstract

A non-contact measurement device with an adjustable range is provided, and includes an amplitude-controllable oscillation module, a sensing module and a current sensor. The amplitude-controllable oscillation module oscillates a driving voltage with fixed amplitude. The sensing module includes an adjustable impedance unit. Besides, the sensing module adjusts the adjustable impedance unit according to an impedance control signal, and radiates an alternating magnetic field by the driving voltage so as to sense a sample under test. The current sensor detects a driving current generated by the amplitude-controllable oscillation module and generates a detection signal related to the sample under test.

Description

Non-contact measuring device with adjustable range

The present invention relates to a non-contact measuring device, and more particularly to a non-contact measuring device having an adjustable range.

The non-contact measuring device can detect the characteristics and defects of the sample to be tested without damaging the sample to be tested, and thus is widely used in today's industry. There are many types of sensing methods for non-contact measuring devices, one of which is to use the eddy current principle for sensing. The principle of eddy current is to couple with the sample to be tested through an alternating magnetic field, so that the sample to be tested induces a vortex current, that is, an eddy current. In addition, the characteristics of the sample to be tested will cause a change in the eddy current flow direction, and the eddy current will form a secondary magnetic field to resist the change of the alternating magnetic field (primary magnetic field), so that it can be detected by the change of the coupling characteristics caused by the sample to be tested. The characteristics of the sample to be tested.

At present, some conventional techniques have been proposed for the non-contact measuring device with the eddy current principle as the main axis, for example, U.S. Patent No. 6,819,120. Among them, U.S. Patent No. 6,819,120 uses a sensing module as a resonant element of an oscillating circuit to oscillate a driving voltage by self-returning resonance. However, since the sensing module is also a resonant component of the oscillating circuit, the oscillating bandwidth of the oscillating circuit will be limited. In order to cope with the above situation, such a measuring device must replace different sensing modules for different samples to be tested.

The invention provides a non-contact measuring device with an adjustable range, which uses an impedance control signal to adjust the measuring range of the sensing module. Thereby, the non-contact measuring device can detect different samples to be tested without replacing the sensing module.

The invention provides a non-contact measuring device with an adjustable range, comprising an amplitude controllable oscillation module, a sensing module and a current sensor. The amplitude controllable oscillating module oscillates a drive voltage having a fixed amplitude. The sensing module includes an adjustable impedance unit. In addition, the sensing module adjusts the adjustable impedance unit according to the impedance control signal, and radiates an alternating magnetic field for sensing the sample to be tested by using the driving voltage. The current sensor is configured to detect a driving current generated by the amplitude controllable oscillating module and generate a detection signal related to the sample to be tested.

In an embodiment of the invention, the non-contact measuring device having the adjustable range further includes a controller. The controller is configured to generate an impedance control signal.

In an embodiment of the present invention, the controller selects one of the plurality of preset comparison tables as a specific comparison table according to the impedance control signal, and the controller queries the specific comparison table according to the detected signal to obtain and test Sample related characteristic values.

In an embodiment of the invention, the sensing module further includes a driving coil, and the sensing module transmits the alternating magnetic field through the driving coil. Wherein, the driving coil is electrically connected to the adjustable impedance unit.

In an embodiment of the invention, the adjustable impedance unit comprises a tunable capacitor and an adjustable resistor. Wherein, the adjustable capacitor and the driving coil are connected in parallel with each other. The first end of the adjustable resistor is electrically connected to the adjustable capacitor, and the second end of the adjustable resistor receives the driving voltage.

Based on the above, the present invention utilizes an impedance control signal to adjust the measurement range of the sensing module. Thereby, the non-contact measuring device can detect different samples to be tested without replacing the sensing module.

The above described features and advantages of the present invention will be more apparent from the following description.

1 is a schematic illustration of a non-contact measuring device having an adjustable range in accordance with an embodiment of the present invention. As shown in FIG. 1 , the non-contact measuring device 100 with an adjustable range includes a sensing module 110 , an amplitude controllable oscillation module 120 , and a current sensor 130 . Further, the sensing module 110 includes an adjustable impedance unit 111 and a driving coil 112.

In operation, the amplitude controllable oscillating module 120 provides a driving voltage V _D to the sensing module 110 such that the driving coil 112 in the sensing module 110 generates an alternating magnetic field. When the alternating magnetic field passes through the sample 101 to be tested, the sample 101 to be tested will induce an eddy current, and the magnitude of the eddy current and the characteristics of the sample 101 to be tested, for example, conductivity, permeability, thickness, defect, and distance. And so on. In addition, the eddy current induced by the sample 101 to be tested radiates a secondary magnetic field to resist the change of the alternating magnetic field (ie, the primary magnetic field) generated by the sensing module 110.

In other words, the sensing module 110 receives a change in the secondary magnetic field, that is, a coupling effect between the sensing module 110 and the sample 101 to be tested. Thereby, the sensing module 110 achieves energy transfer between the sample 101 and the sample 101 to be tested by coupling the magnetic field. In addition, during the coupling process, the relevant information of the sample 101 to be tested will also be coupled to the non-contact measuring device 100 having an adjustable range in a non-contact manner.

In order to make the present inventors have a better understanding of the present embodiment, the coupling effect between the sensing module 110 and the sample 101 to be tested will be described below.

First, the driving coil 112 in the sensing module 110 is viewed from the sample 101 to be tested. 2 is a schematic diagram of a coupling model of a sensing module in accordance with an embodiment of the present invention. Referring to Figure 2, the coupling effect can be approximated using a transformer model. Here, the main coil L ₁ of the transformer T ₂ corresponds to the drive coil 111 in the sensing module 110 , and the current I ₁ corresponds to the drive current generated by the amplitude controllable oscillation module 120 . Furthermore, the eddy current generated by the sample 101 to be tested, that is, the current I ₂ , is equivalent to that generated by the secondary coil L _{2 of} the transformer T ₂ , and R _L is the impedance of the sample 101 to be tested. Wherein, the middle of the transformer T ₂ is separated by air, so there is a coupling coefficient K between 0 and 1.

Referring to the coupling model of FIG. 2, the equivalent impedance Z=X+jY of the sensing module 110 can be calculated and can be represented by the equivalent circuit of FIG. 3, wherein FIG. 3 is a sense of an embodiment of the present invention. The equivalent circuit diagram of the test module, and the real part X and the imaginary part Y of the equivalent impedance Z will be as shown in equations (1) and (2):

According to the formulas (1) and (2), the change of the equivalent impedance of the sensing module 110 includes the change of the impedance R _L of the sample 101 to be tested and the coupling coefficient K. In addition, if the distance between the sensing module 110 and the sample 101 to be tested is fixed, the coupling coefficient K will be a fixed value. Thereby, the equivalent impedance of the sensing module 110 will change correspondingly with the impedance R _{L of} the sample 101 to be tested, thereby achieving the purpose of sensing the sample 101 to be tested.

On the other hand, with respect to the impedance R _{L of} the sample 101 to be tested, the transmission impedance of the electromagnetic wave is approximated by the transmission line theorem by the reflection phenomenon of the electromagnetic wave on the interface, and can be calculated through the penetration reflection of the interface. According to the above principle, if the sample to be tested 101 is a film of a non-magnetic material, the impedance R _{L of} the sample 101 to be tested will approximate the sheet resistance value of the film, and as shown in the formula (3):

Where σ is the electrical conductivity of the material and t is the thickness of the material. In other words, when the sample to be tested 101 is a film of a non-magnetic material, the sheet resistance value of the sample 101 to be tested will be regarded as a resistance and coupled to the sensing module 110 through the alternating magnetic field. That is, the impedance characteristic of the sensing module 110 will be correspondingly changed according to the sheet resistance value of the sample 101 to be tested. For example, according to equations (1) and (2), when the impedance R _{L of} the sample 101 to be tested decreases, the imaginary impedance Y of the sensing module 110 will decrease, and the real impedance X will increase. In addition, a decrease in the imaginary impedance Y will cause the resonant frequency of the sensing module 110 to rise, thereby causing an increase in the angular frequency.

In this implementation, the sensing module 110 further includes an adjustable impedance unit 111, so the coupling model shown in FIG. 2 will be expanded as shown in FIG. 4, wherein FIG. 4 is a sense of another embodiment according to the present invention. Schematic diagram of the coupled model of the test module. Referring to FIG. 4, the adjustable impedance unit 111 includes a tunable capacitor VC and an adjustable resistor VR. The adjustable capacitor VC and the driving coil 112 (that is, the main coil L ₁ ) are connected in parallel with each other, and the first end of the adjustable resistor VR is electrically connected to the adjustable capacitor VC, and the second end of the adjustable resistor VR receives the driving voltage V _D.

Furthermore, referring to the coupling model of FIG. 4, the equivalent circuit of the sensing module 110 can be represented by FIG. 5, wherein FIG. 5 is an equivalent circuit diagram of the sensing module according to another embodiment of the present invention, and Z _in and Z _out are the equivalent input impedance and equivalent output impedance between the adjustable impedance unit 111 and the drive coil 112, respectively. It is to be noted that, in the embodiment of FIG. 1 , the adjustable impedance unit 111 and the driving coil 112 in the sensing module 110 are resonant elements of the amplitude controllable oscillation module 120 , so the sensing module 110 operates. At the resonant frequency.

When operating at the resonant frequency, the complex impedance of the sensing module 110 will have reached a conjugate match. At this time, the equivalent circuit of the sensing module 110 of FIG. 5 can be simplified as shown in FIG. 6, wherein FIG. 6 is an equivalent circuit diagram of the sensing module according to still another embodiment of the present invention, and FIG. The equivalent resistance R _eq , the equivalent inductance L _eq , the adjustable resistance R _s and the adjustable capacitance C _{s in} the equation will be as shown in the equations (4) to (7).

Wherein, Q _L = R _L /ω L ₂ , and the resonance frequency ω _{0 of the} sensing module 110 is as shown in the formula (8).

Referring to FIG. 6, when the sensing module 110 operates at the resonance frequency ω ₀ , the sheet resistance value of the sample 101 to be tested will approximate the series-connected equivalent resistance R _eq and the adjustable resistance R _s . In addition, the average power delivered to the sensing module 110 at this time will be as shown in equation (9):

Where I _Lm is the maximum amplitude of the drive current. When I _Lm = V _D / (2R _eq ), the average power delivered to the sensing module 110 will be maximized. In other words, if the equivalent resistance R _eq is equal to the adjustable resistance R _s , the power delivered to the impedance R _L of the sample 101 to be tested will be maximized. That is, when the sensing module 110 operates at the resonant frequency and the real impedances of the sensing modules 110 match each other, the power delivered to the impedance R _L will be maximized.

In addition, when the sample 101 to be tested causes the equivalent resistance of the sensing module 110 to be R _eq = At ±ΔR _eq , the maximum amplitude I _{Lm of} the drive current will be as shown in equation (10):

According to formula (10), if ±ΔR _{L is} the impedance range of the sample 101 to be measured, which is to be measured by the non-contact measuring device 100, and For the intermediate value of the impedance range to be measured, ΔR _L is the bandwidth of the impedance range to be measured, and may be based on Determining the intermediate value of the equivalent resistance of the sensing module 110 And matching the impedance is designed to increase the sensitivity of the non-contact measuring device 100.

It should be noted that, in actual design, the sensing module 110 further includes an internal resistor R ₁ , and the internal resistor R _{1 is} connected in series with the equivalent resistor R _eq and the equivalent inductor L _eq . In contrast, the maximum amplitude I _{Lm of the} drive current will be further expressed as shown in equation (11).

It should be noted that if the internal resistance R _{1 is} much larger than ΔR _eq , the current change will be quite insensitive. And know that ΔR _{eq is} proportional to 1/R _L . In other words, a sample with a high impedance typically causes the current to become quite insensitive. To solve the above case, the sheet resistance relationship based on coupling, i.e. R _eq K / n ² R _L , the drive coil 112 with a small number of turns can be used to increase the amount of change in _Req . Conversely, when the sample to be tested is a low-impedance conductor, the number of turns of the drive coil 112 should be increased.

In accordance with the above concept, the embodiment of Fig. 1 is reversed. The sensing module 110 can adjust the adjustable impedance unit 111 according to an impedance control signal SI. Thereby, as shown in FIG. 4-6, in a preferred embodiment, the reactance value of the adjustable capacitor VC in the adjustable impedance unit 111 and the resistance value of the adjustable resistor VR will be correspondingly changed. At this time, referring to the formula (8), as the adjustable capacitance VC in the sensing module 110 changes, the resonant frequency ω _{0 of the} sensing module 110 will change accordingly, thereby causing the non-contact measuring device 100 to The samples to be tested are tested for different measurement ranges. In addition, as the adjustable resistor VR in the sensing module 110 changes, the real impedance of the sensing module 110 can be matched to each other, thereby maximizing the delivered energy.

In other words, the sensing module 110 can adjust the measurement range according to the impedance control signal SI. Therefore, although the amplitude controllable oscillating module 120 oscillates in a manner of self-returning resonance, the non-contact measuring device 100 only needs to change the measuring range of the sensing module 110 by using the impedance control signal SI. Test for different samples to be tested. In this way, for different samples to be tested, the operation of replacing the sensing module 110 can be eliminated, thereby helping to improve the convenience of the non-contact measuring device 100 and reducing the hardware cost of the device. Labor costs.

On the other hand, since the sensing module 110 is driven by the amplitude controllable oscillation module 120, the power consumed by the sensing module 110 will also be reflected in the output power of the amplitude controllable oscillation module 120. . In addition, the amplitude controllable oscillating module 120 generates a driving voltage V _D having a fixed amplitude, so that the impedance change of the sensing module 110 will be reflected in the driving current generated by the amplitude controllable oscillating module 120. Therefore, the current sensor 130 is configured to detect the driving current of the amplitude controllable oscillation module 120, and accordingly generate a detection signal SD to reflect the characteristics of the sample 101 to be tested.

It is worth mentioning that in a preferred embodiment, the non-contact measuring device 100 having an adjustable range further includes a controller 140. The controller 140 is configured to generate the impedance control signal SI, and determine the characteristics of the sample 101 to be tested according to the detected signal SD. For example, in one embodiment, the sample 101 to be tested is a film and the film is composed of a non-magnetic material. At this time, the controller 140 will obtain a characteristic value of the sample 101 to be tested, that is, a sheet resistance value of the film, according to the detection signal SD.

In actual operation, the controller 140 stores a plurality of preset comparison tables, and each of the preset comparison tables records the relative relationship between the current value and the sheet resistance value. When the controller 140 sends the impedance control signal SI to control the sensing module 110, the controller 140 further selects one of the plurality of preset comparison tables as the specific comparison table according to the impedance control signal SI. Therefore, when the detection signal SD is sent back to the controller 140, the controller 140 will query the current value in the specific comparison table according to the detection signal SD to obtain the corresponding chip resistance value, that is, the detected to be tested. The sheet resistance value of the sample 101. As a result, it will help to improve the convenience of the non-contact measuring device and reduce the hardware cost and labor cost of the non-contact measuring device.

Furthermore, as shown in FIG. 1 , the amplitude controllable oscillation module 120 includes an oscillation circuit 121 , an amplitude control circuit 122 , and a voltage generator 123 . The oscillating circuit 121 oscillates the driving voltage V _D by using the sensing module 110. That is, the adjustable impedance unit 111 and the driving coil 112 in the sensing module 110 are resonant elements of the oscillating circuit 121 to cause the sensing module 110 to oscillate the driving voltage V _{D in} a manner of self-resonating resonance. On the other hand, the amplitude control circuit 122 receives the driving voltage V _D from the sensing module 110 and converts the received driving voltage V _D into a detecting voltage. In addition, the amplitude control circuit 122 compares the detected voltage with a reference voltage V _R and generates a control information DT according to the comparison result. Wherein the reference voltage V _R is supplied by a voltage generator 123. Thereby, the oscillation circuit 121 adjusts the amplitude of the driving voltage V _D in accordance with the control information DT so that the amplitude of the driving voltage V _D is maintained constant.

Although the embodiment of FIG. 1 exemplifies the implementation of the amplitude controllable oscillating module 120, it is not intended to limit the invention. Those skilled in the art will be able to modify the implementation of the amplitude controllable oscillating module 120 as desired by the design. For example, in a preferred embodiment, the oscillating circuit 121 in the amplitude controllable oscillating module 120 can be replaced with a power amplifier and a phase locked loop. Thereby, the phase-locked loop can oscillate an oscillating voltage by itself and form a driving voltage for driving the sensing module 110 through amplification of the power amplifier. In addition, the power amplifier will maintain the amplitude of the drive voltage generated by the power amplifier based on the control information from the amplitude control circuit 122. Moreover, the input signal received by the phase locked loop is the driving voltage from the sensing module 110, so the sensing module 110 will continuously operate at the resonant frequency. It is worth noting that the amplitude-controlled oscillating module 120 can oscillate the oscillating voltage of different frequencies in conjunction with the measuring range of the sensing module 110 because the phase-locked loop can oscillate the oscillating voltage by itself.

In summary, the present invention utilizes an impedance control signal to adjust the measurement range of the sensing module. Therefore, although the amplitude controllable oscillation module oscillates in a manner of self-receiving resonance, the non-contact measuring device can still detect different samples to be tested without replacing the sensing module. . As a result, it will help to improve the convenience of the non-contact measuring device and reduce the hardware cost and labor cost of the non-contact measuring device.

Although the present invention has been disclosed in the above embodiments, it is not intended to limit the invention, and any one of ordinary skill in the art can make some modifications and refinements without departing from the spirit and scope of the invention. The scope of the invention is defined by the scope of the appended claims.

100. . . Non-contact measuring device with adjustable range

110. . . Sensing module

111. . . Adjustable impedance unit

112. . . Drive coil

120. . . Amplitude controllable oscillation module

121. . . Oscillation circuit

122. . . Amplitude control circuit

123. . . Voltage generator

130. . . Current sensor

101. . . Sample to be tested

SI. . . Impedance control signal

SD. . . Checkout signal

V _D . . . Driving voltage

V _R . . . Reference voltage

DT. . . Control information

T ₂ . . . transformer

L ₁ . . . Main coil

L ₂ . . . Secondary coil

I ₁ , I ₂ . . . Current

R _S , R _L . . . impedance

R _eq . . . Equivalent resistance

L _eq . . . Equivalent inductance

VC, C _s . . . Adjustable capacitor

VR, R _s . . . Adjustable resistance

Z _in . . . Equivalent input impedance

Z _out . . . Equivalent output impedance

1 is a schematic illustration of a non-contact measuring device having an adjustable range in accordance with an embodiment of the present invention.

2 is a schematic diagram of a coupling model of a sensing module in accordance with an embodiment of the present invention.

3 is an equivalent circuit diagram of a sensing module in accordance with an embodiment of the present invention.

4 is a schematic diagram of a coupling model of a sensing module in accordance with another embodiment of the present invention.

FIG. 5 is an equivalent circuit diagram of a sensing module according to another embodiment of the present invention.

6 is an equivalent circuit diagram of a sensing module according to still another embodiment of the present invention.

100. . . Non-contact measuring device with adjustable range

110. . . Sensing module

111. . . Adjustable impedance unit

112. . . Drive coil

120. . . Amplitude controllable oscillation module

121. . . Oscillation circuit

122. . . Amplitude control circuit

123. . . Voltage generator

130. . . Current sensor

101. . . Sample to be tested

SI. . . Impedance control signal

SD. . . Checkout signal

V _D . . . Driving voltage

V _R . . . Reference voltage

DT. . . Control information

Claims (10)

A non-contact measuring device with an adjustable range, comprising: an amplitude controllable oscillation module oscillating a driving voltage having a fixed amplitude; and a sensing module comprising an adjustable impedance unit, wherein the sensing The measuring module adjusts the adjustable impedance unit according to an impedance control signal, and uses the driving voltage to radiate an alternating magnetic field for sensing a sample to be tested; and a current sensor to detect the amplitude controllable oscillation The driving current generated by the module generates a detection signal associated with the sample to be tested. The non-contact measuring device with adjustable range as described in claim 1 further includes: a controller for generating the impedance control signal. The non-contact measuring device with adjustable range as described in claim 2, wherein the controller selects one of the plurality of preset comparison tables as a specific comparison table according to the impedance control signal, and the control The device queries the specific comparison table according to the detection signal to obtain a characteristic value associated with the sample to be tested. The non-contact measuring device with adjustable range as described in claim 3, wherein the sample to be tested is a film composed of a non-magnetic material, and the characteristic value is a sheet resistance value of the film. . The non-contact measuring device with an adjustable range as described in claim 1, wherein the sensing module further comprises a driving coil, and the sensing module transmits the alternating wave through the driving coil a magnetic field, wherein the driving coil is electrically connected to the adjustable impedance unit. The non-contact measuring device with adjustable range as described in claim 5, wherein the adjustable impedance unit comprises: a tunable capacitor connected in parallel with the driving coil; and an adjustable resistor, the first The adjustable capacitor is electrically connected to one end, and the second end of the adjustable resistor receives the driving voltage. The non-contact measuring device with adjustable range as described in claim 6 wherein the adjustable capacitor comprises a varactor. The non-contact measuring device with adjustable range as described in claim 1, wherein the amplitude controllable oscillating module comprises: an amplitude control circuit for receiving the driving voltage from the sensing module, And converting the received driving voltage into a detecting voltage, and the amplitude control circuit compares the detected voltage with a reference voltage, and generates a control information according to the comparison result; and an oscillating circuit, using the sensing The module oscillates the driving voltage, and adjusts the amplitude of the driving voltage according to the control information, so that the amplitude of the driving voltage remains unchanged. The non-contact measuring device with adjustable range as described in claim 8 , wherein the amplitude controllable oscillation module further comprises: a voltage generator for generating the reference voltage. A non-contact measuring device having an adjustable range as described in claim 1, wherein the sample to be tested is a film, and the film is composed of a non-magnetic material.