TWI637184B - Touch screen test method, touch screen test system and automatic test device - Google Patents

Abstract

A touch screen test system includes a thin film transistor and an automatic test circuit. The automatic test circuit stores N first time values and N second time values, and sequentially generates a first and second clock signals. The automatic test circuit is configured to generate a test signal and a source drive signal. The charge pump generates a gate drive signal to output to the gate of the transistor according to the first and second clock signals, and the first time is defined as the time when the second clock signal enters the charging phase and the phase delays the transition state, the second time It is defined as the time during which the second clock signal maintains the pulse wave during the discharge phase. The automatic test circuit performs a signal to noise ratio calculation for each of the N x N feedback signals and determines an optimum signal to noise ratio value. The accuracy of the touch detection is effectively improved by dynamically adjusting the non-overlap time of the first and second clock signals.

Description

Touch screen test method, touch screen test system and automatic test device

The invention relates to a touch screen detection technology, in particular to a touch screen test system, an automatic test device and a touch screen test method capable of dynamically adjusting the non-overlap time of charge pump switch switching.

As shown in FIG. 1 , in the existing touch detection technology, in order to ensure that the scan signal Tx is accurately received by the capacitor Ctouch, it is required to be respectively on the gate and source of a thin film field effect transistor (TFT). A sync signal V _G , V _{S is} superimposed with the scan signal Tx to cancel the parasitic capacitances Cgd, Csd and panel capacitance (ie, Cpanel) of the TFT. In addition, the sync signal V _S on the source can directly utilize the scan signal Tx, and the sync signal V _G on the gate needs to be generated by the charge pump.

As shown in FIG. 2 and FIG. 3, based on the scan signal Tx, a simple delay circuit is used to obtain a non-overlap control signal CLK_CH and CLK_PM with Tx to control the charge pump alternately. The charging phase (ie, the switch SWN is turned on, the switch SWP is not turned on) and the pumping phase (ie, the switch SWN is not turned on, and the switch SWP is turned on). However, since the non-overlap time of the above control signals CLK_CH and CLK_PM does not have flexible adjustability, the automatic adjustable function cannot be realized, and thus the signal-to-noise ratio cannot be effectively improved. In response to the above problems, no effective solution has been proposed yet.

Therefore, it is an object of the present invention to provide a touch screen test system that can not effectively improve the signal to noise ratio due to the inability to adjust the non-overlap time in the existing touch detection process.

Thus, the touch screen test system of the present invention includes a touch screen and an automatic test device.

The touch panel includes a pixel unit and a test end. The pixel unit includes a thin film transistor and a capacitor. The thin film transistor has a gate, a source and a drain. The capacitor is electrically connected to the test end. The thin film transistor is between the drains.

The automatic test device includes a charge pump electrically connected to the gate of the thin film transistor, a receiving end electrically connected to the test end of the touch screen, and an automatic test circuit electrically connecting the charge pump and the receiving end and the test end. The automatic test circuit stores N first time values and N second time values, and sequentially generates one according to one of the N first time values and one of the N second time values. a clock signal and a second clock signal, N is a positive integer, N≧2, the automatic test circuit is configured to generate a test signal to and a source drive signal, and the test signal and the source drive signal are respectively output to the a test terminal and a source of the transistor, wherein the source drive signal is synchronized with the test signal, the charge pump is electrically connected to the automatic test circuit to receive the first clock signal and the second clock signal, and according to the first a clock signal and the second clock signal generate a gate drive signal synchronized with the test signal, the gate drive signal is output to a gate of the transistor, wherein the charge pump is based on the charge clock signal and the The discharge clock signal is operated in a charging phase and a discharging phase. The first time is defined as a time when the second clock signal just enters the charging phase, and the second time is defined as the second clock signal. The time during which the pulse wave is maintained in the discharge phase, wherein the phase of the second clock signal is complementary to the first clock signal.

The receiving end receives N×N feedback signals from the pixel unit, wherein a total of N×N gate driving signals are generated by the combination of the N first time values and the N second time values, and the gate driving signal is generated. The N × N kinds of feedback signals respectively correspond to N × N kinds of gate drive signals.

The automatic test circuit performs a signal to noise ratio operation on each of the N×N feedback signals to obtain N×N signal to noise ratio values.

The automatic test circuit compares the N×N SNR values to determine an optimal SNR value, and records the first time value and the second time value corresponding to the optimal SNR value.

Another object of the present invention is to provide a touch screen test method.

The touch screen test method includes steps (A) to (F).

(A) the automatic test circuit stores N first time values and N second time values, and sequentially according to one of the N first time values and one of the N second time values, A first clock signal and a second clock signal are generated, N being a positive integer, N ≧ 2.

(B) the automatic test circuit is configured to generate a test signal and a source drive signal, the test signal and the source drive signal are respectively output to the test terminal and the source of the transistor, wherein the source drive signal Synchronized to the test signal.

(C) the charge pump generates a gate driving signal synchronized with the test signal according to the first clock signal and a second clock signal, and the gate driving signal is output to a gate of the transistor, wherein the charge pump The charging clock signal and the discharging clock signal are operated in a charging phase and a discharging phase, and the first time is defined as a time when the second clock signal just enters the charging phase, and the phase is delayed. The second time is defined. A time during which the second clock signal maintains a pulse wave in a discharge phase, wherein a phase of the second clock signal is complementary to the first clock signal.

(D) the receiving end receives N×N feedback signals from the pixel unit, wherein a total of N×N gate drivers are generated by the combination of the N first time values and the N second time values The signal, the N×N kinds of feedback signals respectively correspond to N×N kinds of gate driving signals.

(E) The automatic test circuit performs a signal-to-noise ratio operation on each of the N×N feedback signals to obtain N×N signal-to-noise ratio values.

(F) the automatic test circuit compares the N×N SNR values to determine an optimal SNR value, and records the first time value and the second time corresponding to the optimal SNR value. value.

The effect of the invention is to dynamically adjust the non-overlap time of the switching of the charge pump and set the first and second clock signals to make the charge with the first time value and the second time value corresponding to the optimal signal to noise ratio value. The pump generates a gate drive signal, which effectively improves the accuracy of detecting the touch screen.

Before the present invention is described in detail, it should be noted that in the following description, similar elements are denoted by the same reference numerals.

Referring to FIG. 4 and FIG. 5, an embodiment of the touch screen test system of the present invention includes: a touch screen 2 and an automatic test device 3.

The touch panel 2 includes a pixel unit 20 and a test terminal 21. The pixel unit 20 includes a thin film transistor TFT and a capacitor Cpanel. The thin film transistor TFT has a gate, a source and a drain. A capacitor Cpanel is electrically connected between the test terminal 21 and the drain of the thin film transistor TFT. The thin film transistor TFT has parasitic capacitances Cgd and Csd.

The automatic test device 3 includes a charge pump 34 electrically connected to the gate of the thin film transistor TFT, a receiving end 37 electrically connected to the test end 21 of the touch screen 2, and an electrical connection between the charge pump 34 and the receiving end 37. The automatic test circuit 4 with the test terminal 21.

The charge pump 34 is controlled by the first and second clock signals to generate a gate drive signal, and includes four switches SWN, SWP and a capacitor C _F for receiving the first voltage V1 and the second voltage V2, respectively.

The automatic test circuit 4 includes an amplifier 31, an analog-to-digital converter 32, a controller 33, and a test component 30.

The test component 30 includes a switch St and a test capacitor Ct. The switch St has a first end and a second end electrically connected to the receiving end 37, and is controlled to switch between conduction and non-conduction. When in the automatic test mode, the switch St is constantly conducting. The test capacitor Ct has a first end electrically connected to the second end of the switch St and a grounded second end for simulating the human body capacitance Ctouch. As shown in FIG. 6, it is an operation timing chart of the charge pump 34, which will be further described below.

As shown in FIG. 7, the touch screen test system performs a touch screen test method, and the touch screen test method includes the following steps:

Step (A): the automatic test circuit 4 stores N first time values and N second time values, and sequentially according to one of the N first time values and the N second time values. One of them generates a first clock signal CLK_CH and a second clock signal CLK_PM, N being a positive integer, N ≧ 2.

Step (B): the automatic test circuit 4 is configured to generate a test signal Tx and a source drive signal Vs, and the test signal Tx and the source drive signal Vs are output to the test terminal 21 and the transistor TFT, respectively. a source, wherein the source driving signal Vs is synchronized with the test signal Tx.

Step (C): the charge pump 34 receives the first clock signal CLK_CH and the second clock signal CLK_PM, and generates a gate synchronized with the test signal Tx according to the first clock signal CLK_CH and the second clock signal CLK_PM. a driving signal V _G , the gate driving signal V _{G is} output to the gate of the transistor TFT, wherein, as shown in FIG. 6 , the charge pump 34 operates according to the first clock signal CLK_CH and the second clock signal CLK_PM a charging phase and a discharging phase, the first time T1 is defined as a time when the second clock signal CLK_PM just enters the charging phase, and the second time T2 is defined as the second clock signal CLK_PM is discharged. The time during which the pulse width is maintained in the phase, wherein the phase of the second clock signal CLK_PM is complementary to the first clock signal CLK_CH.

When the repeating steps (A) to (C) have performed each of the arrangement combinations of the first and second time values T1, T2 of the N × N types, the process proceeds to step (D).

Step (D): The receiving end receives N×N feedback signals Rx from the pixel unit 20, wherein a total combination of the N first time values T1 and N second time values T2 can generate N× N kinds of gate drive signals V _G , the N × N kinds of feedback signals Rx respectively correspond to N × N kinds of gate drive signals.

Step (E): The automatic test circuit performs a signal-to-noise ratio operation on each of the N×N feedback signals Rx to obtain N×N signal-to-noise ratio values.

Step (F): the automatic test circuit 4 compares the N×N SNR values to determine an optimal SNR value, and records the first time value T1 corresponding to the optimal SNR value and The second time value T2. Further, the automatic test circuit 4 generates the first clock signal CLK_CH and the second clock signal CLK_PM with the first time value T1 and the second time value T2 corresponding to the optimal signal to noise ratio value to control the charge pump 34. A gate drive signal V _{G is} generated.

As shown in FIG. 5, steps (E) and (F) are further described herein. The amplifier 31 is electrically connected to the receiving end Rx to receive each feedback signal Rx. Please amplify the feedback signal Rx. Analog to digital converter 32 is electrically coupled to amplifier 31 to receive the amplified feedback signal and analog to digital conversion to produce a digital signal. The controller 33 is electrically connected to the analog-to-digital converter 32 to receive the digital signal, and performs spectrum analysis on the digital signal to obtain respective energy of the signal and the noise to calculate a signal-to-noise ratio value.

Wherein, the parameter SNR is defined as the signal-to-noise ratio value, and the parameters Es and En are defined as the energy of the signal and the energy of the noise, respectively.

The controller 33 has a first register (not shown) and a second register (not shown) for storing the N different first time values T1, the first The second register is configured to store the N different second time values T2, as shown in Table 1.

<TABLE border="1" borderColor="#000000" width="85%"><TBODY><tr><td> T1 (or T2) </td><td> delay time</td></tr ><tr><td> 0 </td><td> 0 </td><td> 0 </td><td> 0 </td><td> 0 </td><td> 0 </ Td><td> 0*time unit</td></tr><tr><td> 0 </td><td> 0 </td><td> 0 </td><td> 0 </ Td><td> 0 </td><td> 1 </td><td> 1*time unit</td></tr><tr><td> 0 </td><td> 0 </ Td><td> 0 </td><td> 0 </td><td> 1 </td><td> 0 </td><td> 2*time units</td></tr>< Tr><td> ...... slightly</td><td> ...... slightly</td></tr><tr><td> 1 </td><td> 1 </td><td> 1 < /td><td> 1 </td><td> 1 </td><td> 0 </td><td> 62*time units</td></tr><tr><td> 1 < /td><td> 1 </td><td> 1 </td><td> 1 </td><td> 1 </td><td> 1 </td><td> 63* time unit </td></tr></TBODY></TABLE>

Table I

The value of T1 ranges from 000000 to 111111, and the value of T2 ranges from 000000 to 111111. Flexible adjustment of non-overlap time is achieved by any combination of values of T1 and T2. For example, when T2 takes the value 000000, T1 takes the value from 000000 to 111111 in turn. When T2 takes the value of 000001, T1 takes the value from 000000 to 111111 in turn. When T2 takes the value of 000010, T1 is again from 000000 to 111111 takes values in order, ..., and so on, and there are a total of 2 ⁶ × 2 ⁶ = 4096 combinations. That is, when in the automatic test mode, the first time value T1 [5:0] and the second time value T2 [5:0] are automatically adjusted by the controller 33 from low to high. Thereby, the non-overlapping time lengths of the first and second clock signals are automatically adjusted. After each of the first and second time values is adjusted, the corresponding signal to noise ratio data is calculated, and the signal to noise ratio data is stored. After the two values of the first time value T1[5:0] and the second time value T2[5:0] are adjusted (total 4096 combinations), all the stored signal to noise ratio data are stored by the controller 33 ( A total of 4096) are subjected to comparative analysis to determine data of the first and second time values T1 and T2 corresponding to the highest signal-to-noise ratio, and are used to set the gate of the charge pump 34 as a normal operation in the non-automatic test mode. The pole drives the signal V _G to complete the entire automated test process.

In summary, the above embodiments have the advantages that: one dynamically adjusts the non-overlapping time of the switching of the charge pump 34 to obtain various signal to noise ratio values. 2. The first time value T1 and the second time value T2 corresponding to the optimal signal to noise ratio value are used to set the gate pump driving signal V _G to effectively improve the accuracy of detecting the touch screen. The object of the invention can be achieved.

However, the above is only the embodiment of the present invention, and the scope of the invention is not limited thereto, and all the equivalent equivalent changes and modifications according to the scope of the patent application and the patent specification of the present invention are still The scope of the invention is covered.

2‧‧‧ touch screen

20‧‧‧ pixel unit

TFT‧‧‧thin film transistor

21‧‧‧Test end

3‧‧‧Automatic test device

4‧‧‧Automatic test circuit

30‧‧‧Test components

St‧‧ switch

Ct‧‧‧ capacitor

31‧‧‧Amplifier

32‧‧‧ Analog Digital Converter

33‧‧‧Control circuit

34‧‧‧

37‧‧‧ Receiver

A‧‧‧Steps for generating the first and second clock signals

B‧‧‧Steps for generating test signal and source drive signal

C‧‧‧Steps for generating gate drive signals

D‧‧‧Steps for receiving the feedback signal

E‧‧‧Steps of signal-to-noise ratio calculation

F‧‧‧Steps to determine an optimal SNR value

VG‧‧‧ gate drive signal

Vs‧‧‧ source drive signal

Tx‧‧‧ test signal

Rx‧‧‧ feedback signal

CLK_PM second clock signal

CLK_CH first clock signal

Cgd‧‧‧ parasitic capacitance

Csd‧‧‧ parasitic capacitance

C _F ‧‧‧ capacitor

SWN‧‧ switch

SWP‧‧‧ switch

Other features and effects of the present invention will be apparent from the following description of the drawings, wherein: FIG. 1 is a partial circuit diagram of a conventional touch detection technology; FIG. 2 is a circuit diagram of a charge pump; FIG. 4 is a block diagram of an embodiment of the touch screen test system of the present invention; FIG. 5 is a circuit diagram of the embodiment; FIG. 6 is a timing diagram of the embodiment. And FIG. 7 is a flow chart of the method for performing a touch screen test in the embodiment.

Claims (10)

A touch screen test system includes: a touch screen, the touch screen includes a pixel unit and a test end, the pixel unit includes a transistor and a capacitor, the transistor has a gate, a source, and a drain electrically connected between the test end and the drain of the transistor; and an automatic test device comprising a charge pump electrically connected to the gate of the transistor, and a test end electrically connected to the touch screen a receiving end and an automatic test circuit electrically connecting the charge pump and the receiving end and the test end, the automatic test circuit storing N first time values and N second time values, and sequentially according to the N first time One of the values and one of the N second time values generates a first clock signal and a second clock signal, N is a positive integer, N≧2, and the automatic test circuit is configured to generate a test signal And a source driving signal, the test signal and the source driving signal are respectively output to the test terminal and the source of the transistor, wherein the source driving signal is synchronized with the test signal, and the charge pump is electrically connected to the automatic Test circuit to pick up And generating, by the first clock signal and the second clock signal, a gate driving signal synchronized with the test signal according to the first clock signal and the second clock signal, and outputting the gate driving signal to the gate of the transistor a pole, wherein the charge pump operates in a charging phase and a discharging phase according to the charging clock signal and the discharging clock signal, and the first time is defined as a time when the second clock signal enters the charging phase and the phase delay transition state The second time is defined as the time during which the second clock signal maintains the pulse wave in the discharge phase, wherein the phase of the second clock signal is complementary to the first clock signal, and the receiving end receives the N from the pixel unit. ×N feedback signals, wherein a total of N×N kinds of gate driving signals are generated by the combination of the N first time values and the N second time values, and the N×N kinds of feedback signals respectively correspond to N×N kinds of gate driving signals, the automatic test circuit performs signal to noise ratio calculation for each of the N×N feedback signals to obtain N×N signal to noise ratio values, and the automatic test circuit compares the N×× N letters To determine a ratio of the optimum SNR, and the recording time of the first value and the second time value corresponding to the optimum value of the SNR. The touch screen test system of claim 1, wherein the automatic test circuit comprises: an amplifier electrically connected to the receiving end to receive each feedback signal, and the amplified signal is amplified; an analog-to-digital converter, Electrically connecting the amplifier to receive the amplified feedback signal and performing analog to digital conversion to generate a digital signal; a controller electrically connecting the analog to digital converter to receive the digital signal and performing spectrum analysis on the digital signal To obtain the respective energy of the signal and the noise to calculate the signal to noise ratio value. The touch screen test system of claim 2, wherein the controller has a first temporary register and a second temporary register, wherein the first temporary register is configured to store the N different first time values. The second register is configured to store the N different second time values. The touch screen test system of claim 1, wherein the automatic test circuit comprises a switch and a test capacitor, the switch having a first end and a second end electrically connected to the receiving end, and controlled to be turned on Switching between non-conduction, when in the automatic test mode, the switch is always conducting; the test capacitor has a first end electrically connected to the second end of the switch and a grounded second end for simulating a human body capacitance. The touch screen test system of claim 1, wherein the transistor is a thin film transistor. An automatic test device is provided for testing a touch screen, the touch screen includes a pixel unit and a test end, the pixel unit includes a transistor and a capacitor, the transistor has a gate, a source and a a drain, the capacitor is electrically connected between the test end and the drain of the transistor, and the automatic test device comprises: a receiving end electrically connected to the test end of the touch screen; a charge pump electrically connecting the transistor a gate electrode; and an automatic test circuit electrically connecting the charge pump to the receiving end and the test end, the automatic test circuit storing N first time values and N second time values, and sequentially according to the N One of the time values and one of the N second time values, generating a first clock signal and a second clock signal, N being a positive integer, N≧2, the automatic test circuit is configured to generate a a test signal and a source driving signal, the test signal and the source driving signal are respectively output to the test terminal and the source of the transistor, wherein the source driving signal is synchronized with the test signal, and the charge pump is electrically connected Automatic test circuit Receiving the first clock signal and the second clock signal, and generating a gate driving signal synchronized with the test signal according to the first clock signal and the second clock signal, the gate driving signal is output to the transistor a gate electrode, wherein the charge pump operates in a charging phase and a discharging phase according to the charging clock signal and the discharging clock signal, the first time being defined as a phase delay transition state when the second clock signal first enters a charging phase The second time is defined as the time during which the second clock signal maintains the pulse wave in the discharge phase, wherein the phase of the second clock signal is complementary to the first clock signal, and the receiving end receives the pixel unit N×N feedback signals, wherein a total of N×N kinds of gate driving signals are generated by the combination of the N first time values and the N second time values, and the N×N kinds of feedback signals respectively Corresponding to the N×N gate drive signals, the automatic test circuit performs a signal to noise ratio calculation on each of the N×N feedback signals to obtain N×N signal to noise ratio values, and the automatic test circuit compares the signals. N×N SNR signal to noise ratio to determine the optimum value of a, and the recording time of the first value and the second time value corresponding to the optimum value of the SNR. The automatic test device of claim 5, wherein the automatic test circuit comprises: an amplifier electrically connected to the receiving end to receive each feedback signal, and the amplified signal is amplified; an analog-to-digital converter, electrically connected The amplifier receives the amplified feedback signal and performs analog-to-digital conversion to generate a digital signal; a controller electrically connecting the analog digital converter to receive the digital signal, and performing spectrum analysis on the digital signal to The respective energy of the signal and the noise are obtained to calculate the signal to noise ratio value. The automatic test device of claim 6, wherein the controller has a first temporary register and a second temporary register, wherein the first temporary register is configured to store the N different first time values, the first The second register is configured to store the N different second time values. The automatic test device of claim 5, wherein the automatic test circuit comprises a switch and a test capacitor, the switch having a first end and a second end electrically connected to the receiving end, and controlled to be turned on and off Switching between conduction, when in the automatic test mode, the switch is always conducting; the test capacitor has a first end electrically connected to the second end of the switch and a grounded second end for simulating a human body capacitance. A touch screen test method is implemented by a touch screen test system including an automatic test device and a touch screen, the automatic test device including a charge pump, a receiving end and an automatic test The circuit board includes a pixel unit and a test end. The pixel unit includes a transistor and a capacitor. The transistor has a gate, a source and a drain. The capacitor is electrically connected to the test end. Between the drains of the transistor, the automatic test circuit is electrically connected between the charge pump and the receiving end, and the receiving end is electrically connected to the test end. The touch screen test method comprises the following steps: (A) the automatic test circuit stores N first time values and N second time values, and sequentially generating a first clock signal and one according to one of the N first time values and one of the N second time values a second clock signal, N is a positive integer, N≧2; (B) the automatic test circuit is configured to generate a test signal and a source drive signal, and the test signal and the source drive signal are respectively output to the test end and Source of the transistor The source driving signal is synchronized with the test signal; (C) the charge pump generates a gate driving signal synchronized with the test signal according to the first clock signal and a second clock signal, the gate driving signal Outputting to the gate of the transistor, wherein the charge pump operates in a charging phase and a discharging phase according to the charging clock signal and the discharging clock signal, the first time being defined as the second clock signal just entering the charging phase The time of the phase delay transition state, the second time is defined as the time during which the second clock signal maintains the pulse wave in the discharge phase, wherein the phase of the second clock signal is complementary to the first clock signal; (D) The receiving end receives N×N feedback signals from the pixel unit, wherein a total of N×N gate driving signals are generated by the combination of the N first time values and the N second time values, and the gate driving signal is generated. The N×N kinds of feedback signals respectively correspond to N×N kinds of gate driving signals; (E) the automatic test circuit performs signal to noise ratio calculation for each of the N×N feedback signals to obtain N×N Signal to noise ratio value; (F) the automatic test circuit compares the N×N SNR values to determine an optimal SNR value, and records the first time value and the second time corresponding to the optimal SNR value. value.