JP4292612B2 - Surface resistance measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a surface resistance measuring apparatus, and more particularly to a surface resistance measuring apparatus that measures the surface resistance of a conductive film in-line.
[0002]
[Prior art]
A conductive substrate in which a metal or metal oxide film having a low electrical resistance is attached to the surface of glass, ceramic or polymer film is used for applications utilizing the conductivity, such as flat panels such as liquid crystal displays, EL displays and plasma displays. Widely used in electrical and electronic applications such as displays, transparent electrodes such as Taiyo batteries, transparent electrostatic shield plates in window of prawn tubes, transparent electromagnetic shield plates and heating elements.
[0003]
In addition, among these conductive films, those that have selective light transmission are used for window materials for the use of Taiyo energy, and for heat ray reflection in buildings, automobiles, etc., using their infrared light reflection characteristics. It is used as a material.
[0004]
Conventionally, the surface resistance of the conductive film of the conductive substrate as described above is generally measured by a contact-type surface resistance measurement method such as two-terminal or two-probe or four-terminal or four-probe.
[0005]
[Problems to be solved by the invention]
However, the contact surface resistance measurement method described above is a destructive measurement, and industrially, there has been a problem that performance degradation or quality degradation occurs due to generation of scratches on the conductive film surface of the product.
[0006]
A method for measuring the coupling inductance between the electromagnetic induction coil and the conductive film (a method for measuring an eddy current generated by applying a magnetic field) is known in order to prevent the occurrence of scratches on the conductive film surface as described above. Yes.
[0007]
In this method, in order to measure a conductive film having a surface resistance value of about 100Ω / □ or more, it is necessary to considerably increase the strength of the applied magnetic field. The substrate pass line fluctuation (vibration in the normal direction of the board surface) causes the gap between the sensor unit and the conductive film to be measured to fluctuate, and the coupling inductance is not constant, resulting in a large measurement error. There's a problem.
[0008]
The present invention has been made in view of the above circumstances, and its purpose is to perform measurement in line continuously with high accuracy by suppressing measurement errors due to fluctuations in the pass line while preventing deterioration in performance or quality of the conductive film. It is in the point of providing a surface resistance measuring device that can be used.
[0009]
[Means for Solving the Problems]
The structure, operation, and effect of the invention according to claim 1 are as follows.
[0010]
[Constitution]
An eddy current generator for causing an eddy current to flow through the conductive film having an ITO film having a surface resistance of 6 to 2000 Ω / □ adhered on a polyethylene terephthalate film, facing the conductive film with a set interval, and the conductive film A predetermined number of eddy current detectors that detect flowing eddy currents in a state of being separated from the conductive film, and a gap detection unit that includes a laser displacement sensor that detects a gap between the eddy current generator and the conductive film, Based on the detection result of the eddy current detection unit and the detection result of the interval detection unit in a state where the voltage applied to the eddy current generation unit is constant, the surface resistance of the conductive film is determined based on the manufacturing process of the conductive film. calculating means for continuously calculating provided in said calculating unit, based on the calibration curve of the relationship between the eddy current created in advance intervals, said setting the interval detecting unit of the detection result If it is outside the interval, the amount of increase or decrease in eddy current resulting from the deviation from the set interval is obtained, and the amount of increase or decrease in eddy current is corrected or subtracted from the detection result of the eddy current detector, The surface resistance of the conductive film is calculated based on the corrected eddy current value.
[0011]
[Action]
An eddy current is caused to flow through the conductive film at an eddy current generator facing the conductive film with a set interval. For example, by applying a high frequency voltage to a coil such as a ferrite core coil serving as an eddy current generator and bringing the coil close to the conductive film, an eddy current due to high frequency inductive coupling flows through the conductive film.
[0012]
When the voltage is kept constant, the eddy current flowing in the conductive film and the surface resistance of the conductive film are inversely proportional (inversely proportional). Therefore, by detecting the eddy current, the eddy current generator and the conductive film are spaced from each other by the set interval. It is possible to obtain the surface resistance in a state (reference point).
[0013]
In this case, if a calibration curve (calibration curve) is created in advance for the relationship between eddy current and surface resistance, the surface resistance can be easily obtained.
[0014]
In principle, the eddy current tends to decrease as the distance between the conductive film and the eddy current generator increases.
[0015]
Therefore, if the detection result of the interval detection unit deviates from the set interval, the calculation means obtains the increase / decrease amount of the eddy current due to the deviation from the set interval, and the eddy current increase / decrease amount is eddy. Correction that is subtracted or added from the detection result of the current detection unit is performed, and the surface resistance of the conductive film is calculated based on the corrected value of the eddy current.
[0016]
Since the surface resistance of the conductive film is calculated in this way, even if the distance between the conductive film and the eddy current generator changes, an error is less likely to occur in the measured value of the surface resistance of the conductive film.
[0017]
Further, since the surface resistance of the conductive film is measured without contacting the conductive film, it is possible to prevent the conductive film from being damaged.
[0018]
Then, for example, by arranging a plurality of eddy current generation units and eddy current detection units in the width direction of the conductive film manufacturing process, the distribution of the surface resistance in the width direction and the trend in the flow direction of the surface resistance (change over time) Can be requested.
[0019]
[effect]
Accordingly, it is possible to provide a surface resistance measuring apparatus capable of preventing in-line continuous measurement with high accuracy by suppressing measurement errors caused by pass line fluctuations while preventing deterioration in performance or quality of the conductive film.
[0020]
The structure, operation, and effect of the invention according to claim 2 are as follows.
[0021]
[Constitution]
In the configuration of the invention according to claim 1, the number of the interval detection units is smaller than the number of the eddy current generation units.
[0022]
[Action]
In addition to the effects similar to the effects of the configuration of the first aspect, the following effects can be achieved.
[0023]
For example, when the production line speed of the conductive film is a low speed of about 1 m / min or less, it can be considered that the pass line fluctuation occurs almost uniformly in the width direction.
[0024]
In such a case, the surface resistance of the conductive film is calculated by the calculation means based on the detection results of the number of interval detection units smaller than the number of eddy current generation units (for example, one) and the detection results of each eddy current detection unit. Is calculated.
[0025]
As a result, the number of interval detection units can be reduced, and the cost required for the interval detection units can be reduced.
[0026]
[effect]
Therefore, in addition to the effects similar to the effects of the configuration of claim 1, a surface resistance measuring apparatus that can be manufactured at low cost can be provided.
[0027]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0028]
FIG. 1 shows the configuration of a non-contact type surface resistance measuring apparatus according to the present invention.
[0029]
This surface resistance measuring apparatus is arranged so as to face the conductive film 2 on the substrate 1 with a set interval, and to generate an eddy current generating part 3A for causing an eddy current to flow through the conductive film 2; Are provided with a plurality (n) of eddy current sensors 3 comprising an eddy current detector 3B (integrated with the eddy current generator 3A) that detects the eddy currents 3A and the conductive film 2 A plurality (n) of displacement sensors 4 (corresponding to the interval detector) are provided integrally with the eddy current sensor 3, and based on the detection result of the eddy current detector 3B and the detection result of the displacement sensor 4. Thus, a computer 7 (corresponding to calculation means) for calculating the surface resistance of the conductive film 2 is provided.
[0030]
The eddy current generating portion 3A is constituted by a coil such as a ferrite core coil, and a high frequency voltage is applied to the coil, and an eddy current due to high frequency inductive coupling is caused to flow through the conductive film 2 by bringing the coil close to the conductive film 2.
[0031]
The eddy current sensor 3 and the displacement sensor 4 are connected to a sensor amplifier 6 for them via a sensor cable 5. Further, a CRT 8 for displaying the measurement result, a printer 9 for printing out the measurement result, and an alarm device 10 for notifying the operator that the measured surface resistance value is out of the specified range or abnormality are provided. is there.
[0032]
The sensor amplifier 6 includes a high-frequency oscillator, a first A / D converter that converts an analog signal of eddy current into a digital signal, and a second A / D converter that converts an analog signal corresponding to the interval into a digital signal. Is provided.
[0033]
The plurality of eddy current sensors 3 and the displacement sensors 4 are arranged in the width direction of the conductive film 2 in the manufacturing process of the conductive film 2, and the distribution of the surface resistance in the width direction and the trend in the flow direction of the surface resistance (over time) Change) can be obtained by the computer 7.
[0034]
The computer 7 performs data processing based on the digital signals obtained by the first and second A / D converters, and if the detection result of the displacement sensor 4 deviates from the set interval, the computer 7 has deviated from the set interval. The amount of increase / decrease in the eddy current due to the eddy current is calculated, and the amount of increase / decrease in the eddy current is corrected or subtracted from the detection result of the eddy current detection unit 3B. Based on the corrected value of the eddy current, The surface resistance is calculated. This calculation method will be described in detail later.
[0035]
Next, the operation of the surface resistance measuring apparatus having the above structure will be described.
[0036]
1) The eddy current sensor 3 and the displacement sensor 4 are arranged in a state where the eddy current generator 3A faces the conductive film 2 on the substrate 1 with a set interval of several mm.
[0037]
2) A high frequency is applied from the sensor amplifier 6 to the eddy current generator 3A of the eddy current sensor 3, and an eddy current is generated in the conductive film 2 by high frequency inductive coupling.
[0038]
3) If the applied high-frequency voltage is controlled to be constant, the eddy current flowing in the conductive film 2 and the surface resistance of the conductive film 2 are inversely proportional (inversely proportional). By creating a calibration curve (calibration curve) for the relationship between the surface resistance and the surface resistance, the conductive film 2 and the eddy current generator 3A are separated from the unknown conductive film 2 in the state (reference point) with the set interval therebetween. Surface resistance can be determined.
[0039]
4) Since the eddy current tends to decrease in principle as the distance between the conductive film 2 and the eddy current generator 3A increases, the eddy current and the interval (the eddy current generator 3A The detection result of the eddy current detection unit 3B is corrected based on a calibration curve (calibration curve) (see FIG. 3) regarding the relationship with the distance between the conductive films 2.
[0040]
5) Next, the above correction method will be described.
[0041]
For example, in the case of a conductive film having a surface resistance of 6Ω / □, the eddy current at the reference point is 66%, but the interval is −1 mm, that is, the eddy current (of the eddy current sensor 3) due to the pass line variation in the in-line. When the interval between the generating portion 3A and the conductive film 2 is reduced by 1 mm, the eddy current is 78%, and the measured value is 12% larger than the actual surface resistance.
[0042]
Therefore, in this case, correction is performed by subtracting 12% from the value of the eddy current detected by the eddy current detector 3B of the eddy current sensor 3.
[0043]
On the contrary, when the interval is +1 mm, that is, when the interval between the eddy current generator 3A and the conductive film 2 is increased by 1 mm, the value of the eddy current is 54%, and the measured value is 12% smaller than the actual surface resistance. Become.
[0044]
Therefore, in this case, correction is performed by adding 12% to the eddy current detected by the eddy current detector 3B. By making such corrections, errors in surface resistance measurement can be suppressed even if there is a pass line variation.
[0045]
As described above, by preparing a calibration curve as shown in FIG. 3 in advance for the conductive film 2 having a known surface resistance, the correction value can be easily obtained correctly.
[0046]
The surface resistance displayed by the computer 7 is subjected to data processing as measured values and graphs by arbitrary creation software, and continuous surface resistance measurement is performed in-line.
[0047]
The calculation of the surface resistance of the conductive film 2 can be continuously performed in the manufacturing process of the conductive film 2 by the calculation cycle of the computer 7.
[0048]
By feeding back the measurement result of the surface resistance to the alarm device 10 and the manufacturing process, the surface resistance can be controlled during the manufacturing, and the quality and productivity in the manufacturing process can be improved.
[0049]
Since the eddy current sensor 3 and the displacement sensor 4 are integrally provided, the eddy current and the distance can be measured at substantially the same point when the conductive film production line speed is about 1 m / min or higher. Measurement accuracy can be improved.
[0050]
[Another embodiment]
When the production line speed of the conductive film 2 is a low speed of about 1 m / min or less, it can be considered that the pass line fluctuation occurs almost evenly in the width direction. The eddy current sensor 3 may be configured to have only one displacement sensor 4.
[0051]
That is, the number of the displacement sensors 4 is set to be smaller than the number of the eddy current generators 3A. Thereby, the cost concerning the displacement sensor 4 can be suppressed low.
[0052]
The displacement sensor 4 should have a high resolution and good accuracy. If the resolution is 10 μm and the accuracy is ± 5% or less, a more accurate measurement result can be obtained.
[0053]
The eddy current sensor 3 and the displacement sensor 4 may be formed separately.
[0054]
The set interval is not limited to the numerical value of the above embodiment, but when set to 3 mm or less, a more accurate measurement result can be obtained.
[0055]
The displacement sensor 4 can be constituted by a displacement sensor such as a capacitance type, an ultrasonic type, a laser type, or a photoelectric type.
[0056]
The computer 7 can be a personal computer, a factory computer, or the like.
[0057]
The number of the eddy current generation unit 3A, the eddy current detection unit 3B, and the displacement sensor 4 is not limited to the number in the above embodiment, and can be changed as appropriate.
[0058]
【Example】
Examples of the present invention will be described.
[0059]
The non-contact type surface resistance measuring apparatus used in this example is shown below.
A measurement range of 1Ω / □ to 2000Ω / □ was used as a high-frequency eddy current sensor (built-in ferrite core coil), and 2 MHz was applied with a high-frequency transmitter.
[0060]
As the conductive film, an ITO (Indium Tin Oxide) film on a PET (Poly Ethylene Terephthalate) film was attached, and several films having different surface resistance values in the range of 6 to 2000Ω / □ were used.
[0061]
A laser displacement sensor is used as the displacement sensor, and the measurement range is 0 to 3 mm, the resolution is 10 μm, and the measurement accuracy is ± 3%.
[0062]
The sensor amplifier included a 16-bit A / D converter. A personal computer was used as a calculator for correcting the surface resistance.
[0063]
In order to evaluate the validity of the measurement results of this example, the surface resistance value of the conductive film used in this example was measured in advance by the four-probe method of JIS K7194 standard.
[0064]
FIG. 4 shows a comparison between the non-contact type surface resistance measurement result according to this example and the surface resistance measurement result by the four-probe method of the JIS K7194 standard.
[0065]
FIG. 5 shows the relationship between the pass line fluctuation and the measurement result according to this example. FIG. 6 shows the improvement in measurement accuracy with respect to the pass line fluctuation according to this embodiment.
[0066]
As a result, the surface resistance value measured according to this example coincided with the surface resistance value measured by the four-probe method of JIS K7194 standard with a correlation coefficient of 0.99 or more. Further, when the pass line fluctuation is within ± 3 mm, the non-contact type surface resistance measurement can be measured with an accuracy of ± 5% or less.
[Brief description of the drawings]
FIG. 1 is a schematic diagram of a surface resistance measuring device. FIG. 2 is a diagram showing a calibration curve (calibration curve) for the relationship between eddy current and surface resistance. FIG. 3 is a calibration curve for the relationship between eddy current and separation distance. Fig. 4 is a diagram showing a comparison of surface resistance measurement results. Fig. 5 is a diagram showing the relationship between pass line fluctuation and measurement results. Fig. 6 is a diagram showing improvement in measurement accuracy. ]
2 conductive film 3A eddy current generator 3B eddy current detector 4 interval detector 7 calculation means

Claims (2)

An eddy current generator for causing an eddy current to flow through the conductive film having an ITO film having a surface resistance of 6 to 2000 Ω / □ adhered on a polyethylene terephthalate film, facing the conductive film with a set interval, and the conductive film A predetermined number of eddy current detectors that detect flowing eddy currents in a state of being separated from the conductive film, and a gap detection unit that includes a laser displacement sensor that detects a gap between the eddy current generator and the conductive film, Based on the detection result of the eddy current detection unit and the detection result of the interval detection unit in a state where the voltage applied to the eddy current generation unit is constant, the surface resistance of the conductive film is determined based on the manufacturing process of the conductive film. calculating means for continuously calculating provided in said calculating unit, based on the calibration curve of the relationship between the eddy current created in advance intervals, said setting the interval detecting unit of the detection result If it is outside the interval, the amount of increase or decrease in eddy current resulting from the deviation from the set interval is obtained, and the amount of increase or decrease in eddy current is corrected or subtracted from the detection result of the eddy current detector, A surface resistance measuring device configured to calculate the surface resistance of the conductive film based on the corrected value of the eddy current.   The surface resistance measuring apparatus according to claim 1, wherein the number of the interval detection units is smaller than the number of the eddy current generation units.

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