WO2011021825A2

WO2011021825A2 - Apparatus and method for inspecting a capacitive touch screen panel using lc resonant frequency variation

Info

Publication number: WO2011021825A2
Application number: PCT/KR2010/005409
Authority: WO
Inventors: 고재준; 김영권
Original assignee: 주식회사 에프티랩
Priority date: 2009-08-17
Filing date: 2010-08-17
Publication date: 2011-02-24
Also published as: WO2011021825A3; TW201128205A; CN102187319A; CN102187319B; KR100971220B1; JP5403640B2; TWI431293B; JP2011527440A

Abstract

The present invention relates to an apparatus and method for inspecting defects in a capacitive touch screen panel (CTSP) regardless of the shape of an ITO pattern and without using a dedicated controller chip for a CTSP in testing defects of the CTSP. The inspection apparatus according to the present invention comprises: an LC resonant unit having an LC resonant circuit coupled to the capacitance between ITO sensor electrodes of the CTSP to induce electric resonance; an OP amplifier driving unit which is connected to the LC resonant unit to oscillate the LC resonant circuit of the LC resonant unit, and which converts the waveform of a resonant frequency into square waves; a relay unit which is connected to the LC resonant unit to interconnect the LC resonant circuit and the ITO sensor electrodes of the CTSP symmetrically parallel to each other; and a microcomputer unit which is connected to the OP amplifier driving unit to drive the relay unit, and which counts the square waves outputted by the OP amplifier driving unit in order to measure a frequency and to determine whether or not there are defects in the CTSP.

Description

Inspection device and method of capacitive touch screen panel using LC resonance frequency variation

The present invention relates to an inspection apparatus and an inspection method for determining whether there is a defect in the manufacturing step of the capacitive touch screen panel (hereinafter referred to as "CTSP"), more specifically, between the good and defective products of the CTSP By precisely measuring the difference in capacitance between the ITO touch sensor electrodes present in the LC resonance frequency difference measurement technique, it is possible to accurately determine the failure of the CTSP ITO electrode pattern without the CTSP dedicated controller chip. It relates to an apparatus and a test method.

In general, a touch screen panel attached to a display screen of a mobile phone or a kiosk and used for various buttons or information input by a hand touch has a resistive film type and a capacitive type. The dual capacitive touch screen panel, CTSP, generally has a structure as shown in FIG. A sensor electrode film 120 having a lower ground film 110 at the bottom and a transparent ITO electrode pattern serving as a touch sensor thereon, and a dielectric film 130 attached to the ITO electrode with an adhesive thereon; The upper protective film 140 is composed of. The shape of the ITO electrode 150 pattern, which is a touch sensor electrode, depends on the performance and the driving method of the dedicated controller chip for each manufacturer, but the overall basic structure is as described above, and in particular, the capacitance between the ITO sensor electrodes is maintained. Is common to all four companies. That is, as shown in FIG. 2, all CTSPs have an equivalent circuit in the form of a series-parallel coupling of the capacitors 210 existing between the ITO electrodes and the capacitors 220 generated by the lower ground.

When the FPC 320 in which the dedicated controller chip 310 shown in FIG. 3 is attached to the CTSP having the structure as described above is attached to the touch screen module, an operation for measuring the position at which a human hand is touched on the CTSP is performed. This becomes possible.

The operation principle of CTSP is as follows. When a human hand comes into contact with the CTSP, the capacitance between the ITO electrodes at the site of contact is different from the initial value. The change of this value is measured by the phase delay change of the electrical signal pulse applied to the ITO electrode by the dedicated controller chip 310, and analyzed by the algorithm embedded in the chip 310 to obtain the position information of the hand contact with the CTSP. That's how it's done. Therefore, the role of the dedicated controller chip is very important functionally in the operation of the touch screen module. If the CTSP's ITO electrode pattern design changes, the interelectrode capacitance changes according to the changed shape, and a new dedicated controller chip designed and programmed accordingly must be used.

Each CTSP manufacturer takes the production stage up to the state of the touch screen module. Existing electrical property quality inspection is conducted using a dedicated controller chip in the state of the CTSP or touch screen module. Therefore, if the CTSP model is changed and the ISP electrode pattern of the CTSP is changed, there is an inconvenience of having to use a tester equipped with a different dedicated controller chip each time. In addition, the capacitance between the ITO sensor electrodes, which determines the electrical characteristics of the CTSP, cannot be known using a conventional controller chip. In addition, since dedicated chips determine defects by measuring the phase delay time of signal pulses, they are vulnerable to changes in external environmental conditions such as EMI and have poor measurement accuracy.

The present invention has been made in view of the above-mentioned aspect, and it is possible to use LC resonant frequency variation that can identify defective products by precisely inspecting CTSP's electrical characteristics without CTSP controller chip and regardless of the ITO electrode pattern of CTSP. An object of the present invention is to provide an inspection apparatus and an inspection method of a capacitive touch screen panel.

An electrostatic capacitive touch screen panel inspection apparatus using an LC resonant frequency shift according to the present invention provided to achieve the above object is an LC including an LC resonant circuit that generates electrical resonance by coupling with capacitance between ITO sensor electrodes of a TSP. Resonator; An op amp driving unit configured to continuously oscillate the LC resonant circuit of the LC resonator and convert the waveform of the resonant frequency into a square wave; the LC resonant circuit and the ITO sensor electrode of the CTSP are continuously connected to the LC resonator. A relay unit symmetrically connected in parallel; And a micom unit configured to drive the relay unit in succession with the OP amplifier driver, measure the frequency by counting the square wave output from the OP amplifier driver, and determine whether the CTSP is defective.

Here, the microcomputer unit measures the LC resonant frequency shift generated as much as the capacitance between the ITO electrodes is added to the C value of the LC resonant circuit, and divides it by an average value to standardize the calculated value within the range of the resonant frequency shift of the good product. It is desirable to determine whether or not the CTSP is defective.

In addition, it is preferable that the resonant frequency variation range of the good product is standardized by dividing the LC resonant frequency variation by an average value, and it is determined whether or not it exists in a user-specified good product range.

An inspection method of a capacitive touch screen panel using an LC resonance frequency variation according to the present invention provided to achieve the above object,

In the inspection method of the capacitive touch screen panel (CTSP) using the LC resonant frequency variation, the LC resonance circuit and the LC resonance circuit to generate an electrical resonance coupled with the capacitance between the ITO sensor electrodes of the CTSP and at the same time oscillates the LC resonance circuit It includes an OP amplifier driving unit for converting the square wave so that the microcomputer unit can count the frequency, the relay unit and the microcomputer unit,

In order to obtain the reference resonance frequency due to the oscillation of pure LC only, the micro resonance unit measures the LC resonance frequency value by frequency counting the reference resonance frequency of only the LC resonance circuit without connecting CTSP and LC resonance circuit. Stage 1;

The relay unit operated by the signal of the microcomputer unit sequentially connects the ITO sensor electrode of the CTSP and the LC resonant circuit in pairs, and at this time, the resonance frequency variation generated by adding the capacitance between the ITO electrodes to the C value of the LC resonant circuit. A second step of measuring and storing a value with the microcomputer unit;

Repeating step 2, obtaining a distribution of resonant frequency variations of the various CTSPs measured by the micom unit, setting a good range, and storing it in a memory of the micom unit;

The microcomputer unit calculates the resonant frequency variation value between specific channels stored by standardization, and compares the resonant frequency variation value of the product stored in the microcomputer unit to determine whether the product is within the resonance frequency variation range of the product. Step 4; characterized by including.

In the fourth step, the LC resonance frequency variation is generated by measuring the C value of the LC resonant circuit plus the capacitance between the ITO electrodes, and divides the average value by the average value to normalize the resonance frequency variation range of the good product. It is desirable to determine whether the CTSP is defective according to whether or not it is included in the inside.

In addition, the resonant frequency variation range of the good product is normalized by dividing the LC resonant frequency variation by the average value, it is good to determine whether it exists in the user-designated good range.

According to the inspection apparatus and the inspection method of the capacitive touch screen panel using the LC resonance frequency variation according to the present invention has the following effects.

Since the abnormality of the capacitance value between the ITO electrodes of the CTSP is measured by the LC resonance frequency, regardless of the type of the ITO pattern, regardless of the type of the CTSP, it is possible to determine whether the CTSP is defective without the controller chip dedicated to the CTSP.

In addition, since the inspection circuit using the electrical resonance phenomenon is used, due to the inherent stability of the resonance phenomenon, it is resistant to electric shock such as electrostatic shock or external EMI and is insensitive to external environmental change factors such as mechanical vibration or temperature and humidity change. In measurement, it is possible to maintain measurement accuracy of 1/1000 or more by counting the frequency, not the voltage or current, with a counter.

In addition, since the actual capacitance value between the ITO electrodes of the CTSP can be obtained through the LC resonance circuit constant and the resonance frequency relation, it can be easily used for failure analysis.

1 is a structural diagram of each CTSP layer,

2 is a diagram showing an equivalent circuit of an ITO electrode of a general CTSP;

3 is a view showing a general completed touch screen module structure,

4 is a circuit diagram of a CTSP inspection apparatus using LC resonance according to an embodiment of the present invention;

5 is a graph showing the variation of the resonance frequency of each channel of the good product CTSP according to an embodiment of the present invention,

FIG. 6 is a graph illustrating standardization and range of goods of the result of FIG. 5;

7 is a graph showing an example (1) of a failure determination;

8 is a graph showing an example (2) of a failure determination, and

9 is a graph showing an actual capacitance measurement result between ITO terminals of the CTSP.

The above objects, features and other advantages of the present invention will become more apparent by describing the preferred embodiments of the present invention in detail with reference to the accompanying drawings. Hereinafter, an electrostatic capacitive touch screen panel inspection apparatus and an inspection method using an LC resonance frequency variation according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. For the purposes of this specification, the same reference numerals in the drawings represent the same components unless otherwise indicated.

Hereinafter, the inspection method of the CTSP according to the present invention with reference to the accompanying drawings will be described in detail.

First, the circuit of the inspection apparatus of the CTSP using LC resonance to which the inspection method of the present invention is applied is shown in FIG. As shown in FIG. 4, the test circuit basically includes an LC resonator 410, an op amp driver 420, a relay 430, and a microcomputer 440.

The LC resonator 410 is a coil having an inductance value of several hundred uH and a reference capacitor of less than 100 pF because the capacitance between the ITO electrodes of the CTSP is generally very small, several tens of pF. Configure an LC resonant circuit so that the reference resonant frequency is in the range of 600kHz to 800kHz.

The OP amplifier driver 420 serves to oscillate the LC resonant circuit, and also converts the resonant frequency waveform from a sine wave to a square wave to facilitate frequency counting of the microcomputer 440.

The relay unit 430 is a device for sequentially connecting the LC resonant circuit and the ITO sensor electrodes of the CTSP in parallel to each other and is operated by receiving a signal from the microcomputer unit 440.

The microcomputer unit 440 drives the relay unit 430, counts the resonance frequency pulse signal (square wave) output from the OP amplifier driving unit 420, measures the frequency, and calculates the capacitance conversion and whether the CTSP is defective. Perform the calculation function.

In the inspection apparatus according to the present invention, noise is not generated on the circuit of the OP amplifier driver 420 for converting an analog signal generated in the LC resonance circuit of the LC resonator 410 into a digital pulse counter, and the microcomputer unit ( When measured in 440), the accuracy is very high, with an error range of 0.1%.

Next, a process of measuring the capacitance between the ITO sensor electrodes, which governs the electrical characteristics of the CTSP, by the resonance frequency variation using the inspection circuit of FIG. 4 described above will be described.

First, when all the relay units 430 are disconnected and the ITO sensor electrodes of the CTSP are not connected to the LC resonant circuit, that is, the reference resonance frequency due to the oscillation of only the LC of the resonant circuit is measured by the microcomputer unit 440.

Subsequently, the relay 430 is driven by an operation signal of the microcomputer unit 440 so that the ITO sensor electrodes of the CTSP are adjacent to each other on the touch surface, and that the upper and lower symmetric pairs are formed at the electrode terminals, that is, for example, 10 ITO electrodes If present, first and 10, then 2 and 9 are sequentially connected to the LC resonant circuit, and the capacitance between the ITO electrodes is added to the C value of the LC resonant circuit, resulting in variation of the resonance frequency. When the resonance frequency shift value is measured using the microcomputer unit 440, the capacitance value between the ITO electrodes of the CTSP can be measured by one-to-one conversion in terms of the difference in the resonance frequency shift. Such a measuring method is a general purpose that is always applicable regardless of the type of CTSP since it is irrelevant to the pattern of the ITO sensor electrode of the CTSP. In addition, the measurement accuracy is measured by counting the frequency, not the voltage or current value, so that accurate measurement is possible regardless of the electrical noise which adversely affects the measurement at all times.

Structurally, since it uses a PCB that has the same pitch as the ITO electrode of the CTSP, unlike the probe using the pin, there is no damage of the electrode of the CTSP by the surface contact method, and the cell is measured by the direct measurement so that the measurement impedance and the low noise are low. Has characteristics. In addition, even if the type of CTSP is changed, by simply replacing the PCB and applying it, it is possible to apply the inspection device at low cost regardless of the type of all CTSPs.

5 is a graph showing the variation of the resonant frequency of each channel of the good quality CTSP according to an embodiment of the present invention, FIG. 6 is a standardization of the result of FIG. 5 and a range setting of good quality, and FIG. 7 is an example of failure determination (1 ), FIG. 8 is a graph showing an example (2) of failure determination, and FIG. 9 is a graph showing the actual capacitance measurement result between the ITO terminals of the CTSP.

5 to 9, an actual inspection process for performing a defect inspection of CTSPs will be described by way of example. First, the reference resonance frequency of the CTSP inspection apparatus was measured by the microcomputer 440, which was 680 kHz. Then, the resonant frequencies of the normal CTSP samples and their average values are obtained. The actual result is shown in FIG.

FIG. 5 is a diagram illustrating 10 CTSP normal samples for a mobile phone having 32 terminals measured and displayed by measuring the resonance frequency shifted by capacitance between terminals which are symmetrically paired by the above-described method. The measured values 510 of channel 3 indicated by dotted lines in FIG. 5 are obtained when the

terminals

3 and 30 are connected to the tester in the 10 CTSP samples. The meaning of the remaining channels is the same. The following process normalizes the measured transition frequency by the average value. The results are shown in FIG. Referring to FIG. 6, all the result data are within an error range within ± 1% indicated by a dotted line 610, and the result data is stored in the memory of the microcomputer by setting the resonance frequency variation range of the good products. In this way, the frequency variation range of the product is determined, and when subsequent CTSP inspection, the microcomputer measures the resonance frequency variation between specific channels, calculates it by standardization, and compares it with the stored product range value. do. The following is an example of a defect determination. 7 and 8 show the results of the CTSP samples determined to be defective. It can be clearly seen that the two data indicated by the dotted line 710 in FIG. 7 and the plurality of data values in FIG. 8 greatly out of range of the good. FIG. 9 shows the results of the measurement of FIG. 7 converted into actual capacitance of the CTSP using the relational expression of the LC resonance circuit. In this case, the LCs used in the test circuit were L = 1mH and Cref = 30pF, respectively. In other words, if the resonance frequency variation is measured, the actual capacitance is also known.

As a result, all data are measured and stored for each channel, and the measured value can be used for standard management of production by judging the quantity / defect by physical quantity such as frequency and capacitance.

According to the capacitive touch screen panel inspection apparatus and inspection method using the LC resonant frequency shift according to the present invention as described above, regardless of the type of CTSP, regardless of the type of the ITO pattern by using the LC resonance frequency shift, There is an effect that can determine whether CTSP is defective even without a dedicated controller chip.

In addition, since the inspection circuit using the electrical resonance phenomenon is used, due to the inherent stability of the resonance phenomenon, it is resistant to electric shock such as electrostatic shock or external EMI, and has a very insensitive effect on external environmental change factors such as mechanical vibration or temperature and humidity change. In measurement, it is possible to maintain measurement accuracy of 1/1000 or more by counting a frequency other than voltage or current with a counter.

In addition, since the actual capacitance value between the ITO electrodes of the CTSP can be obtained through the LC resonance circuit constant and the resonance frequency relation, there is an effect that can be easily used for failure analysis.

While preferred embodiments of the present invention have been described above, the present invention is not limited to the above-described specific embodiments. That is, those skilled in the art to which the present invention pertains can make many changes and modifications to the present invention without departing from the spirit and scope of the appended claims, and all such appropriate changes and modifications are possible. Equivalents should be considered to be within the scope of the present invention.

Claims

An LC resonator including an LC resonant circuit coupled with a capacitance between the ITO sensor electrodes of the CTSP to cause electrical resonance;

An OP amplifier driving unit which is continuous with the LC resonator and oscillates the LC resonant circuit of the LC resonator, and converts the waveform of the resonant frequency into a square wave;

A relay unit connected to the LC resonant circuit and the ITO sensor electrode of the CTSP in symmetrical parallel with the LC resonator;

And a microcomputer unit configured to drive the relay unit in succession with the OP amplifier driver, measure the frequency by counting the square wave output from the OP amplifier driver, and determine whether the CTSP is defective. Capacitive touch screen panel inspection device using.
The method of claim 1, wherein the microcomputer unit

Measure the LC resonant frequency variation generated by adding the capacitance between the ITO electrodes to the C value of the LC resonant circuit, and divide the average value by the average value to determine whether the CTSP is within the resonant frequency variation range of the good product. Capacitive touch screen panel inspection apparatus using the LC resonant frequency shift characterized in that it determines the defect.
The method of claim 2,

The resonant frequency variation range of the good product is standardized by dividing the LC resonant frequency variation by an average value, and determining whether or not present in the user-specified good range. Capacitive touch screen panel inspection device using the LC resonant frequency variation.
In the inspection method of the capacitive touch screen panel (CTSP) using the LC resonance frequency variation,

LC resonant circuit coupled with the capacitance between the ITO sensor electrode of the CTSP to cause electrical resonance, and an op amp drive unit for converting the LC resonant circuit into a square wave so that the microcomputer can count the frequency and the relay unit and the microcomputer unit and,

In order to obtain the reference resonance frequency due to the oscillation of pure LC only, the micro resonance unit measures the LC resonance frequency value by frequency counting the reference resonance frequency of only the LC resonance circuit without connecting CTSP and LC resonance circuit. Stage 1;

The relay unit operated by the signal of the microcomputer unit sequentially connects the ITO sensor electrode of the CTSP and the LC resonant circuit in pairs, and at this time, the resonance frequency variation generated by adding the capacitance between the ITO electrodes to the C value of the LC resonant circuit. A second step of measuring and storing a value with the microcomputer unit;

Repeating step 2, obtaining a distribution of resonant frequency variations of the various CTSPs measured by the micom unit, setting a good range, and storing it in a memory of the micom unit;

A fourth step of calculating whether or not the microcomputer is in the range of the good or out of the good by comparing the value of the non-defective product stored in the microcomputer with the standardized calculation of the stored resonant frequency shift value between specific channels; Capacitive touch screen panel inspection method using an LC resonant frequency shift characterized in that it comprises a.
The method of claim 4, wherein

In the fourth step, the LC resonant frequency variation generated as much as the value of the capacitance between the ITO electrodes is added to the C value of the LC resonant circuit, divided by the average value, and the standardized calculated value falls within the resonant frequency variation range of the good product. Capacitive touch screen panel inspection method using an LC resonant frequency variation characterized in that it determines whether the CTSP is defective depending on whether or not.
The method of claim 5,

The resonant frequency variation range of the good product is standardized by dividing the LC resonant frequency variation by an average value, and judged by the presence or absence in the range specified by the user characterized in that the capacitive touch screen panel inspection method using the LC resonant frequency variation.