KR101929323B1 - Apparatus for Detecting Touch in Capacitive Touchscreen- Equipped Devices - Google Patents

Abstract

[0001] The present invention relates to a capacitance type touch screen panel inspecting apparatus, in which a self capacitance value of an ITO layer of a CTSP is measured using a level difference difference of a source signal from a winbridge type oscillator, It is an object of the present invention to judge the pattern defect of the ITO layer, the abnormality of the ITO film and the contamination state, and measure the capacitance value between the ITO film and the lower film to judge the good product / defect according to the abnormality.
SUMMARY OF THE INVENTION It is an object of the present invention to provide a capacitive touch screen panel capable of measuring the self capacitance value of an ITO layer of a capacitive touch screen panel using a difference in level of a source signal from a winbride type oscillator, A capacitance type touch screen panel inspecting apparatus comprising: a relay board connected to the capacitive touch screen to measure a capacitance value of each channel; A signal measuring unit for generating an oscillation frequency for measuring capacitance on the relay board and measuring a feedback signal; And a central processing unit which controls each of the units and compares the measured value inputted from the signal measuring unit with a predetermined reference value to determine whether or not the signal measuring unit and the central processing unit are defective, .

Description

[0001] Apparatus for Detecting Touch in Capacitive Touchscreen [

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pattern inspection method of a capacitive touch screen panel (hereinafter abbreviated as 'CTSP'), and more particularly, The self capacitance of the layer is measured and compared with the measured value of the standard sample to judge whether the pattern of the ITO layer is abnormal, the abnormality of the ITO film quality or contamination, or the capacitance value between the ITO phase and the sub- ) Of the touch screen panel to determine a good product / defect according to the abnormality.

Generally, the touch screen panel has a capacitive touch screen that senses and drives the static electricity generated by the human body. It is mainly used for a touch screen which is durable, has a short reaction time, is permeable, and is multi-touch capable. On the other hand, the resistive or pressure sensitive touch screen is a pressure sensitive touch screen which is inexpensive and can be written in a handwriting or small cell with a stylus pen. However, It is disadvantageous in that it is not perceptible when pressed and is slightly dull compared to the electrostatic touch method.

Herein, in order to determine whether the capacitive touchscreen is in operation by checking the operation state, a method of inspecting a capacitive touch screen panel using LC resonance frequency variation as disclosed in Korean Patent Registration No. 10-0971220 .

FIG. 1 is a circuit diagram for testing a capacitance type touch screen panel using LC resonance frequency variation according to the related art. The inspection circuit basically includes an LC resonance part 410, an OP amplifier driving part 420, a relay part 430 and a micom 440. Since the capacitance between the ITO electrodes of the CTSP is very small, which is a few tens of pF, the LC resonator 410 generally has a reference capacitor of less than 100 pF and a few hundred uH An LC resonance circuit is constituted by a coil having an inductance value so that the reference resonance frequency is a value in the range of 600 kHz to 800 kHz.

The OP-amplifier driving unit 420 serves to oscillate the LC resonance circuit and to transform the resonance frequency waveform from a sinusoidal wave to a square wave to facilitate frequency counting of the micom.

The relay unit 430 is a device for sequentially connecting the LC resonance circuit and the ITO sensor electrodes of the CTSP in pairs in order, and operates in response to a signal from the microcomputer.

The microcomputer unit 440 drives the relay, counts the resonance frequency pulse signal output from the operational amplifier, measures the frequency, and calculates the electrostatic capacity and determines whether the CTSP is defective or not.

The thus configured conventional technique measures the presence or absence of an abnormality in the capacitance value between the ITO electrodes of the CTSP by the LC resonance frequency, and therefore, regardless of the type of the ITO pattern, whether the CTSP is defective or not is determined without using the CTSP dedicated controller chip Because it uses the inspection circuit using electrical resonance phenomenon, it is resistant to electric shock such as electrostatic shock and external EMI due to inherent stability of resonance phenomenon. It is very resistant to external environmental factors such as mechanical vibration or temperature and humidity change. Insensitive In measurement, the measurement accuracy can be maintained at 1/1000 or more by measuring the frequency, not the voltage or the current, by counting with the counter.

However, the inspection method of the capacitance type touch screen panel using the LC resonance frequency variation according to the related art has been problematic in that the precision is somewhat deteriorated because it is inspected using the frequency change measurement in the LC resonance circuit.

Therefore, in order to solve the above problems, the present invention provides a method of measuring the self capacitance value of the ITO layer of the CTSP using the difference in the level of the source signal from the oscillator of the winbridge system for more accurate measurement, And a capacitance of the capacitance of the ITO layer and the capacitance of the ITO layer are measured to determine whether the ITO layer is abnormal or not, the ITO film quality is abnormal or contaminated, The present invention relates to a touch screen panel inspection apparatus.

To attain the object of the present invention, a capacitive touch screen panel inspecting apparatus measures a self capacitance value of an ITO layer of a capacitive touch screen panel using a difference in level of a source signal from a winbride type oscillator The present invention relates to a capacitive touch screen panel inspecting apparatus using a win bridge oscillator for judging the amount and the deficiency of a touch panel, the apparatus comprising: a relay board connected to the capacitive touch screen for measuring a capacitance value of each channel; A signal measuring unit for generating an oscillation frequency for measuring capacitance on the relay board and measuring a feedback signal; And a central processing unit which controls each of the units and compares the measured value inputted from the signal measuring unit with a predetermined reference value to determine whether or not the signal measuring unit and the central processing unit are defective, .

Here, the relay board includes an interface with the main board; A connection terminal portion for connecting a touch screen panel for inspection; And a "horizontal & vertical" channel for measuring the capacitance of the touch screen panel.

The signal measuring unit may include: a constant voltage unit for supplying power; A win bridge generator which generates an oscillation frequency for measuring a capacitance with a voltage input from the constant voltage unit; A resistance bridge section for measuring a resistance value; And a rectifier for rectifying a signal fed back from the relay board and outputting the rectified signal to the central processing unit.

The capacitive touch screen panel inspection apparatus according to the present invention inspects whether the touch screen panel is defective before or during the process of putting the touch screen panel into the TSP assembling process in the state of the ITO film or the cell cutting state, It is possible to prevent the bad touch screen panel from continuing to the subsequent process.

Also, by using sophisticated win bridge oscillator as a signal source, precise measurement is possible and it is easy to measure even a large capacity value of a large touch screen panel by applying a positive voltage of 30Vp-p with an oscillation voltage, Is measured and converted into a DC level, so that there is no error according to the conversion formula.

In addition, compared with a touch screen panel inspection apparatus using a conventional LC resonant circuit, measurement of a change in voltage with respect to a frequency change measurement is effected, thereby enabling more precise measurement.

FIG. 1 is a circuit diagram for testing a capacitance type touch screen panel using LC resonance frequency variation according to the related art,
2 is a block diagram of a capacitive touch screen panel testing apparatus using a win bridge oscillator according to an embodiment of the present invention,
3 is a flowchart of a touch screen panel inspection process using the present invention,
4 is a conceptual diagram for explaining the present invention,
5 is a configuration diagram of a win- rate oscillator and a signal measuring unit according to an embodiment of the present invention,
6A and 6B are a circuit diagram and frequency waveform diagram of a win bridge oscillator according to an embodiment of the present invention,
7 is a circuit diagram for explaining the calculation of the win bridge oscillator according to the present invention,
8 is a bridge circuit diagram of a rectifying unit according to an embodiment of the present invention,
9 is a view showing an embodiment of a function graph for converting an ADC value to a capacitance value,
10 is a flowchart of a measurement and inspection process using a capacitive touch screen panel inspection apparatus using a win bridge oscillator according to the present invention.

The configuration and operation of a capacitive touch screen panel inspection apparatus using a win bridge oscillator according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 2 is a block diagram of a capacitive touch screen panel inspection apparatus according to an embodiment of the present invention. The apparatus includes a relay board 110 connected to the CTSP 100 for measuring the capacitance value of each channel, A signal measuring unit 120 for generating an oscillation frequency for measuring capacitance on the board 110 and measuring a feedback signal from the signal measured by the signal measuring unit 120 and a signal measuring unit 120 for controlling the units 110 and 120, A DC power supply unit 151 for supplying power to the signal measuring unit 120 and a DC power supply unit for supplying power to the central control unit 130 A liquid crystal display part 152 for displaying a menu display and a measurement value for inspection of the touch screen panel according to the control of the control part 130 and a keyboard 153 for user selection connected to the central control device 130, The signal measuring unit 120 and the central control unit 130 are connected to the main It is mounted on the load (140).

The relay board 110 includes an interface unit 111 for interfacing with the main board 140, a connection terminal unit 113 for connection with the CTSP 100, a connection terminal unit 113 connected to the connection terminal unit 113, And a plurality of relays 112 having channels of "horizontal and vertical" according to a touch pattern of CTSP for measuring the capacitance of the CTSP 100.

Also, the relay boards 110 and 110a may use two or more relay boards 110 and 110a at the same time.

The signal measuring unit 120 includes a constant voltage unit 121 for supplying power, a winbrike oscillator 122 for generating an oscillation frequency for measuring a capacitance at a voltage input from the constant voltage unit 121, A resistor bridge unit 123 for measuring a resistance value R between the ITO layer patterns existing in the CTSP 100 and a control unit 120 for rectifying a signal fed back from the relay board 110 and outputting the signal to the central processing unit 130 And a rectifying unit 124 for rectifying the rectified voltage.
The operation of the capacitive touch screen panel inspection apparatus using the win bridge oscillator according to the embodiment of the present invention will now be described in detail with reference to FIGS. 2 to 10.

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As shown in FIG. 2, the present invention measures the actual impedance value of the capacitance of the CTSP, which is the DUT, by using the winbridean oscillator 122 as a signal source, and outputs the measured impedance to the rectifying unit 124 And converts the converted DC level into a DC level. The converted DC level is inputted to the central control unit 130 and compared with the set level of the normal state, and it is determined whether the DC level is normal or bad according to the result.

FIG. 2 is a block diagram of a capacitive touch screen panel testing apparatus using a win bridge oscillator according to an embodiment of the present invention. Referring to FIG. 2, the AC power source AC is supplied to a DC power source DC through a power supply unit 151, ± 30 V to supply to the main board 140 and the supplied DC power source ± 30 V is converted into ± 12 V from the constant voltage section 121 of the signal measuring section 120 and supplied.

The win bridge oscillator 122, which is supplied with the power of ± 12 V from the constant voltage unit 121, generates an oscillation frequency for capacitance measurement using an RC circuit.

The oscillation frequency generated by the win bridge oscillator 122 sequentially drives each relay unit 112 for each channel through the interface unit 111 of the relay board 110 and the oscillation frequency generated by the connection terminal unit 113 A capacitance measurement value of a channel for each pattern set in the CTSP 100 is input to the rectifying unit 124 of the signal measuring unit 120 through the interface unit 111. [

Here, the relay board 110 is composed of two relay boards 110 and 110a in a horizontal and vertical (X 128 * Y 128 channels), and each relay board 110 can extend up to 256 channels.

The rectifying unit 124 rectifies the capacitance measurement signal of the CTSP 100 fed back through the relay unit 110 and inputs the signal to the central control unit 130.

4 is a view for explaining the basic principle of the capacitance measurement using the RC circuit of the win bridge oscillator according to the present invention. The resistance value 'R' is a resistivity component between patterns formed by ITO and the like, and the capacitance 'C' Is a capacitance component, and the resistance value 'R' is measured by the resistance bridge portion 123.

A rectangular wave having a specific frequency generated by the constant voltage unit 121 is applied to the R and C components existing in the CTSP 100 and the voltage drop caused by these reactance components is measured to measure the value of the capacitance to be measured .

The phase shift that occurs at this time is ignored because it is not necessary in the measurement.

5 is a configuration diagram of a win- drite oscillator and a signal measuring unit according to an embodiment of the present invention. The square-wave generator includes a win-bridge shaping wave generator 122a and a comparator 122b. The win- And converts the square wave into a square wave using the comparator 122b and outputs it.

The square wave generated through the square wave generator is applied to the object CTSP 100 to change its amplitude while the half wave rectification is performed through the rectifier 124 in order to convert the changed square wave into a DC level. That is, the half-wave rectified square wave is converted into direct current wave which is easy to quantitatively analyze and outputted to the central controller 130.

6A and 6B are a circuit diagram and a frequency waveform diagram of a win bridge oscillator according to an embodiment of the present invention. Since the win bridge oscillator responds only at the set pass frequency fr, the frequency value is as shown in the following equation (1).

Because the low pass filter and the high pass filter must meet at a specific frequency fr, the R and C values are determined to have the specifications of the two filters.

On the other hand, the pass frequency is determined by the two filters, only the frequency passes, and the remaining signal disappears while resonating.

FIG. 7 is a circuit diagram for explaining the calculation of the win bridge oscillator according to the present invention. The win bridge oscillator utilizes the oscillation characteristic of the amplifier U1, such as an OP amplifier having a high open loop gain, And a sine wave of a specific frequency is obtained by using a high-pass filter and a low-pass filter.

The transfer function of time (τ +) to the frequency from the output of the circuit to the non-inverting input is given by the following equation (2).

In addition, the transfer function to the inverting input is expressed by the following equation (3).

The loop gain for oscillation is expressed by the following equation (4). Where A _d s is the open loop gain of the differential amplifier and the non-inverting gain of the differential amplifier is calculated from the value of τ + and inverse τ- by the following equation (4).

Therefore, the oscillation frequency is defined by the following equation (5).

The definition of the expression (5) is based on the condition of the following expression (6).

8 is a bridge circuit diagram of a rectifying part according to an embodiment of the present invention. In order to convert a rectangular wave signal whose amplitude and phase are changed by a capacitance value generated by an applied frequency component of a sinusoidal wave into a DC component, And passes the differential amplifier for off-set adjustment.

FIG. 9 shows an embodiment of a function graph for converting an ADC value to a capacitance value, which is calculated by the following equation (7).

Here, yo = -3.888, a = 0.5644 , b = 1.5845x10 -4, c = 6.1116x10 - ^7.

The DC level, ADC, and electrostatic capacity converted by the above equation are shown in Table 1 below.

DC level ADC Capacitance (Cap.) No Touch 0.1225V 25 10 pF Touch 0.2744V 56 30pF Delta 0.1519V 31 20pF

As described above, in the win bridge circuit, the most stable and linear output frequency band (12.2KHz) is applied to the win-bridge oscillator through a lot of experiments, and the influence of external influences (temperature, Humidity, etc.).

When the rectified capacitance measurement signal is inputted to the central processing unit 130 and compared with the capacitance of the preset normal range, it is judged as a defective CTSP when the measured capacitance is out of the set normal range.

FIG. 10 is a flow chart of a measurement and inspection process using a capacitive touch screen panel inspection apparatus using a win bridge oscillator according to the present invention. The capacitance and capacitance of a CTSP determined as a standard sample for setting a capacitance range of CTSP And stores the measured data.

When changing the product, set the number of horizontal and vertical channels (x, y ch.) And determine whether it is applicable to the previous model.

The capacitance of the mass production CTSP for measurement and inspection is measured, and the measured capacitance is compared with the stored standard sample value.

Here, the nonlinearity of the measured DC level signal is compensated as follows. That is, the measured data has a nonlinear characteristic with respect to the measured capacitance value. The measured data based on the standard capacitance value is applied to the best fit line. In this case, the absolute value of the measured capacitance is Although there may be a slight error, the reproducibility of the measured value depends on the stability and precision of the measuring circuit, so that excellent characteristics can be obtained.

The measured capacitance and the value of the standard sample are compared with each other, and it is determined whether the measured capacitance is within the allowable range of the good or bad judgment criteria. The permissible range setting can be arbitrarily set by the user, preferably 1 to 100% Setting.

If it is within the allowable range, it is passed through good product. If it is out of the allowable range, it is judged as bad.

Although specific embodiments of the present invention have been described and illustrated above, it is obvious that the capacitive touch screen panel testing apparatus using the win bridge oscillator of the present invention can be variously modified by those skilled in the art.

It should be understood, however, that such modified embodiments are not to be understood individually from the spirit and scope of the invention, and such modified embodiments are intended to be included within the scope of the appended claims.

100: Capacitive Touch Screen Panel
110: Relay board 111: Interface part
112: Relay 113: Connection terminal part
120: signal measuring unit 121: constant voltage unit
122: win bridge oscillator 123: resistance bridge
124: rectification part 130: central processing unit
140: main board 151: power supply unit
152: liquid crystal display part 153: keyboard

Claims (5)

A capacitance-type touch screen using a win-bridge oscillator that measures the self capacitance value of the ITO layer of the capacitive touch screen panel using the difference in level of the source signal from the oscillator of the win-bridge system, A panel inspection apparatus comprising:
A relay board connected to the capacitive touch screen for measuring a capacitance value of each channel;
The signal measuring unit generates a oscillation frequency for capacitance measurement on the relay board and generates a oscillation frequency for capacitance measurement with a voltage input from a constant voltage unit for supplying power to the relay board A signal measuring unit including a resistance bridge unit for measuring a resistance value between the ITO layer patterns of the touch screen panel and a rectifying unit for rectifying a signal fed back from the relay board and outputting the rectified signal to the central processing unit; And
And a central processing unit which controls the relay board and the signal measuring unit and compares the measured value inputted from the signal measuring unit with a predetermined reference value to judge whether it is defective or not,
The signal measuring unit and the central processing unit are mounted on one main board,
Wherein the relay board comprises: an interface unit with the main board;
A connection terminal portion for connecting a touch screen panel for inspection; And
And a plurality of relays of "horizontal " and "vertical" channels for measuring capacitance of the touch screen panel
Wherein the relay sequentially measures each channel and simultaneously connects a plurality of relay boards. delete delete delete delete

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