TWI530693B - Test circuit and test method of sensing wires in touch panel - Google Patents

Description

Touch panel sensing line detection circuit and detection method

The invention relates to a detection circuit and a detection method of a touch screen.

At present, touch devices with touch functions are becoming more and more popular. The touch device includes a touch panel, and a touch sensor is disposed in the touch panel to sense a touch operation for the touch. For the design of the medium and large size touch panel sensing lines, in order to reduce the impedance of the sensing line, two wires (metal/metal trace) are usually disposed at both ends of each sensing line, and the two traces are connected to a driving chip. The same pin receives the same signal. The way the two ends of the sensing line are connected to the two traces is usually called a double routing wire (see the publication number: US2013/0106747 A1). Patent literature). When testing whether the sensing line (such as Tx) of the double-ended line is broken, a test voltage is usually provided by a trace connected to the sensing line Tx, and another sensing line different from the direction in which the sensing line extends is used. The value of the voltage output from another trace connected (such as Rx) is compared with the value range of the normal double-ended trace (for example, 8000~1200). However, due to the sensing line process of the double-ended line, etc., the value of the double-ended sensing line of the open circuit usually does not fall below the lower limit of the numerical range, but is in the middle lower range, such as 8500. Therefore, the prior art judges whether the sensing line of the double-ended line is broken or not.

In view of the above, it is necessary to provide an accurate detection circuit for judging whether the sensing line of the touch screen is a double-ended trace or not.

It is also necessary to provide an accurate detection method for judging whether the sensing line of the double-ended wiring is broken.

A detecting circuit is configured to detect whether the sensing line in the touch panel is open, the sensing line includes a plurality of first sensing lines extending in a first direction and a plurality of second sensing lines extending in a second direction, each Two ends of a sensing line are electrically connected to a first trace, and two ends of each second sensing line are respectively electrically connected to a second trace, and the detecting circuit comprises a test power source, a conversion circuit and a processing unit, and the test The power supply is configured to provide a voltage signal with equal voltage values and frequencies of the first frequency and the second frequency to the first trace, the conversion circuit is configured to receive the voltage signal output from the second trace and convert the first to the first a value and a second value, the processing unit compares the difference between the first value and the second value, when the absolute value of the difference between the first value and the second value is greater than or equal to a predetermined value, The processing unit determines that the first sensing line is open.

A detecting method is configured to detect whether a sensing line in the touch panel is broken, the sensing line includes a plurality of first sensing lines extending in a first direction and a plurality of second sensing lines extending in a second direction, each Two ends of a sensing line are electrically connected to a first trace, and two ends of each second sensing line are electrically connected to a second trace, respectively, the method includes: providing a voltage value equal to each other and having a frequency of first Frequency and second frequency voltage signals to the first trace; receiving voltage signals output from the second trace and correspondingly converting to the first value and the second a value; determining whether an absolute value of the difference between the first value and the second value is greater than or equal to a preset value; and when an absolute value of the difference between the first value and the second value is greater than or equal to a preset When the value is, the first sensing line is broken.

Compared with the prior art, the detection circuit of the present invention and the detection method using the detection circuit provide voltage signals having different voltage values at the same frequency to the two first traces of the first sensing line, and the second sensing The voltage signals of the outputs of the two second traces are converted into a first value and a second value. When the absolute value of the difference between the first value and the second value is greater than or equal to a predetermined value, the first sensing line is broken. By implementing the present invention, a more precise technical effect of judging whether the sensing line is broken or not is achieved.

1‧‧‧Detection circuit

2‧‧‧ touch panel

10‧‧‧Test power supply

30‧‧‧Transition circuit

50‧‧‧Processing unit

Vin‧‧‧ test signal output

Vout‧‧‧ signal receiving end

21‧‧‧First sensing line

22‧‧‧Second sensing line

23‧‧‧First Trace

24‧‧‧Second Trace

21a‧‧‧The first sub-sensing line

21b‧‧‧Second sub-sensing line

R ₀ , R ₁ , R ₂ , R ₃ ‧‧‧ resistance

C1‧‧‧ capacitor

D1‧‧‧ first direction

D2‧‧‧ second direction

f ₁ ‧‧‧first frequency

f ₂ ‧‧‧second frequency

A, B, P1, P2, Q‧‧‧ nodes

M‧‧‧ midpoint

D‧‧‧ Breakpoint

FIG. 1 is a schematic diagram of the presence of a sense line break in the touch panel 2 for detecting a double-ended trace of the detection circuit 1 of the present invention.

2 is a schematic diagram showing the direction of signal attenuation when the first traces of the second sub-sensing line are connected to each other.

3 is a schematic diagram of the equivalent resistance of the second sub-sensing line shown in FIG. 2.

FIG. 4 is an equivalent circuit diagram of detecting the signal output terminal Vin to the signal receiving terminal Vout when the second sub sensing line is disconnected.

FIG. 5 is a schematic diagram of signal attenuation when the connection point of one end of the first sub-sensing line and one of the first sensing traces is broken.

6 is the output of the test signal when detecting whether the first sub-sensing line is disconnected in FIG. An equivalent circuit diagram of Vin to the signal receiving end Vout.

FIG. 7 is a flow chart of a method for detecting whether a sensing line of a double-ended line is broken or not according to the detection circuit of the present invention.

Please refer to FIG. 1 , which is a schematic diagram of the sensing circuit 1 for detecting a double-ended trace in the touch panel 2 in which the sensing line is broken. The touch panel 2 includes a plurality of first sensing lines 21 extending in the first direction D1 direction and a plurality of second sensing lines 22 extending in the second direction D2. The first direction D1 is not parallel to the second direction D2, and the first direction D1 and the second direction D2 may be an X-axis direction and a Y-axis direction of the rectangular coordinates, respectively. The two ends of each of the first sensing lines 21 are respectively connected to a pin of a driving chip (not shown) by a first trace 23 for receiving a driving signal outputted from the pin of the driving chip. In this embodiment, the two first traces 23 at the two ends of each of the first sensing lines 21 are connected to the same node and then connected to the same pin of the driving chip, wherein the node receives the external driving chip for the first sensing line 21 The position of the generated signal, such as node P1 and node P2 in FIG. Two ends of each second sensing line 22 are respectively connected to another pin of the driving chip by two second traces 24 for transmitting the signal sensed on the second sensing line 22 to the chip. . The chip changes the signal according to the second sensing line 22 to determine the position generated by the touch action. In this embodiment, the two second traces 24 at each end of each second sensing line 22 are connected to the same node and then connected to the same pin of the driving chip, wherein the node is the second sensing line 22 on which the second sensing line 22 is connected. The signal change is transmitted to the location of the drive wafer, such as node Q in Figure 1.

In the case where the plurality of first sensing lines 21 have an open circuit or a continuous path, in order to facilitate the introduction of the working principle of the detecting circuit 1, two of the plurality of first sensing lines 21 are taken as an example to illustrate a first sensing line of the broken circuit. 21 is named as the first sub-sensing line 21a, constantly A first sensing line 21 of the road is named as the second sub sensing line 21b. The two first traces 23 of the first sub-sensing line 21a are connected to the same point P1. The two first traces of the second sub-sensing line 21b are connected to the same point P2. The two second traces 24 of the second sense line 22 are connected to the same point Q. It will be understood that points P1, P2 and Q are respectively different pin connection points to the drive wafer.

The detection circuit 1 includes a test power source 10, a conversion circuit 30, and a processing unit 50. The test power supply 10 includes a test signal output terminal Vin, and the test power supply 10 is configured to provide a voltage signal having the same frequency as the first frequency f ₁ and the second frequency f ₂ and output through the test signal output terminal Vin and the node P1. Up to two first traces 23. The first frequency f ₁ is significantly different from the frequency of the second frequency f ₂ . In the embodiment, the first frequency f ₁ is 100 kHz, and the second frequency f ₂ is 150 kHz. The voltage value of the voltage signal is 1.0V.

The conversion circuit 30 includes a signal receiving end Vout, and the signal receiving end Vout connects the two second traces 24 via the node Q. The conversion circuit 30 is configured to convert the two second traces 24 of the second sensing line 22 to the corresponding values via the voltage signal of the output of the node Q. Specifically, when the frequency of the voltage signal is the first frequency f ₁ , the conversion circuit 30 converts the voltage signals of the two second traces 24 of the second sensing line 22 to the signal receiving end Vout via the node Q into The first value. When the frequency of the voltage signal is the second frequency f ₂ , the conversion circuit 30 converts the voltage signals output by the two second traces 24 of the second sensing line 22 to the signal receiving end Vout into a second value. The conversion circuit 30 has a measurement range of 0 to Va, wherein Va is an upper limit of the measurement range. In the present embodiment, the conversion range of the conversion circuit 30 is (0 to 1.8 V), that is, Va = 1.8 V, and the number of conversion bits is 14 bits of an analog-to-digital converter (ADC).

The processing unit 50 is configured to receive the first value and the second value, and determine whether an absolute value of the difference between the first value and the second value is greater than or equal to a preset value. When the absolute value of the difference between the first value and the second value is greater than or equal to the preset value, the first sensing line 21 is broken. When the absolute value of the difference between the first value and the second value is less than the preset value, the first sensing line 21 does not have an open circuit.

For convenience of description, the frequency of the voltage signal is a first frequency f ₁ corresponding to the value, called first value, the first value when the first sense line 21 is not referred to as a first interruption corresponding to the original value, i.e., voltage signal When the frequency is the first frequency f ₁ , the value corresponding to the second sub-sensing line 21 b is the first original value; when the first sensing line 21 is disconnected, the corresponding first value becomes the first test value, that is, the voltage signal The frequency corresponding to the first sub-sensing line 21a when the frequency is the first frequency f ₁ is the first test value. Similarly, the value of the voltage signal corresponding to the second frequency f ₂ is referred to as a second value, and the second value corresponding to the first sensing line 21 is not referred to as a second original value, that is, a voltage signal. When the frequency is the second frequency f ₂ , the value corresponding to the second sub-sensing line 21 b is the second original value, and the second value corresponding to the first sensing line 21 when the circuit is disconnected is called the second test value, that is, the voltage signal. When the frequency is f ₂ , the value corresponding to the first sub-sensing line 21 a is the second test value.

Please refer to FIG. 2 and FIG. 3 together. FIG. 2 is a schematic diagram of the signal attenuation direction when the two first sensing lines 21b are connected to the two first traces 23 at both ends. FIG. 3 is a schematic diagram of the equivalent resistance of the second sub-sensing line 21b shown in FIG. 2. If the resistance of the second sub-sensing line 21b when the first trace 23 is not connected is R ₀ , the ends A and B of the second sub-sensing line 21b are respectively connected by a first trace 23 to drive the same wafer. When the pin is on, the signal on the second sub-sensing line 21b is attenuated from the node of the first trace 23 and the second sub-sensing line 21b to the midpoint M of the first sensing line 21. Then, the second sub-sensing line 21b is equivalent to the parallel connection of the two R ₀ /2 resistors, that is, the resistance of the second sub-sensing line 21b is R ₀ /4, for convenience of description, The resistance of the second sub-sensing line 21b is defined as R ₁ , that is, R ₁ =R ₀ /4.

Please refer to FIG. 4 , which is an equivalent circuit diagram of the test signal output terminal Vin to the signal receiving end Vout when detecting whether the second sub sensing line 21 b is disconnected. Wherein R _{2 is} the equivalent resistance of the second sensing line 22, and the second sensing line 22 is assumed to be not broken due to the detection, and the positions of the first sub sensing line 21a and the second sub sensing line 21b are both The position of the intermediate point of the first sub-sensing line 21a and the second sub-sensing line 21b, therefore, the resistance R _{2 of} the second sensing line 22 is ignored and not calculated when the calculation is analyzed below. The following is an operation example in which the resistor R ₁ is 50 KΩ and the capacitor C ₁ is 10 pf. Qualitative analysis calculation and detailed description are carried out using the calculation method of the first-order circuit zero-state response.

The second sub-sensing line 21b is analyzed as follows: when the frequency of the voltage signal generated by the test power source 10 is the first frequency f ₁ =100KHZ, then t ₁ =1/f ₁ =10 ^-5 s, the time constant τ ₁ =R ₁ ×C ₁ =5×10 ⁴ ×10 ^-11 =5×10 ^-7 , then the voltage value Vout ₁ =V(1-e ^-t/τ )1.0V output by the second sensing line 22 is The first original value D ₁₀ = (Vout _{1 /} Va) = ( _1/ 1.8) × 2 ¹⁴ = 9102 converted by the conversion circuit 30.

When the frequency of the voltage signal generated by the test power source 10 is the second frequency f ₂ =150KHZ, then t ₂ =1/f ₂ =1/15×10 ⁻⁵ s, τ ₂ =R ₁ ×C ₁ =5× 10 ^-7 , the voltage value Vout ₂ = V(1-e - ^{t / τ} ) 1.0V output by the second sensing line 22, and the second original value D ₂₀ = (Vout ₂ ) converted by the conversion circuit 30 /Va)=(1/1.8)×2 ¹⁴ =9102.

Therefore, for the second sub-sensing line 21b, the difference between the first original value D ₁₀ and the second original value D ₂₀ corresponding to the voltage signals of the first frequency f ₁ and the second frequency f ₂ respectively The value is zero and is less than a preset value (for example, 200).

Please refer to FIG. 5 and FIG. 6. FIG. 5 is a schematic diagram showing signal attenuation of the connection point end of one end of the first sub-sensing line 21a and one of the first sensing traces 23 of the first sub-sensing line 21a. FIG. 6 is an equivalent circuit diagram of the test signal output terminal Vin to the signal receiving end Vout when the first sub-sensing line 21a is disconnected in FIG. 5 . As shown in FIG. 5, the signal on the first sub-sensing line 21a is attenuated from the end A of the first trace 23 to the interruption point D. At this time, the first sub-sensing line 21a is in the resistance of the detecting circuit 1. The resistance R ₃ on the left side of the midpoint M of the first sub-sensing line 21a in FIG. 1 is R ₀ /2. That is, R ₃ = 2R ₁ , and the coupling capacitance of the first sub sensing line 21a and the second sensing line 22 does not change.

The first sub-sensing line 21a is analyzed as follows: when the frequency of the voltage signal generated by the test power source 10 is the first frequency f ₁ =100KHZ, then t ₁ =1/f ₁ =10 ^-5 s, the time constant τ ₃ =2R ₁ × C ₁ = 4 × 5 × 10 ⁴ × 10 ^-11 = 1 × 10 ^-6 , the voltage value of the second sensing line 22 is output Vout ₃ = V(1-e - ^{t / τ} ) 0.993V Then, the first test value D ₁₁ converted by the conversion circuit 30 is (Vout ₃ /Va)=(0.993/1.8)×2 ¹⁴ =9047.

When the frequency of the voltage signal generated by the test power source 10 is the second frequency f ₂ =150 KHZ, then t ₂ =1/f ₂ =1/15×10 ⁻⁵ s, τ ₄ =2R ₁ ×C ₁ =4× 5×10 ⁴ ×10 ^-11 =2×10 ^-6 , the voltage value Vout ₄ =V(1-e ^−t/τ ) output of the second sensing line 22 is 0.964V, and is converted by the conversion circuit 30. The second test value D ₂₁ = (Vout _{4 /} Va) = (0.964 / 1.8) × 2 ¹⁴ = 8775.

Therefore, for the second sub-sensing line 21b, the difference between the first test value D ₁₁ corresponding to the voltage signal of the first frequency f ₁ and the second frequency f ₂ and the second test value D ₂₁ The value is D ₁₁ -D ₂₁ =9047-8775=272, which is greater than or equal to the preset value.

It can be understood that the interruption point of the first sensing line 21 can also be other positions, and the difference in the position of the interruption point is different from the equivalent resistance of the first sensing line 21. The second sensing line 22 senses when the first sensing line 21 is supplied with the voltage signals of the first frequency f ₁ and the second frequency f ₂ due to the difference in the equivalent resistance of the first trace 21 . The voltage values are different, and the values obtained by the conversion circuit 30 are different, thereby being used as a basis for determining whether the first sensing line 21 has an open circuit. The corresponding resistance of the first sensing line 21 is related to the position of the interruption point. Therefore, the voltage corresponding to the first frequency f ₁ and the second frequency f ₂ can be sensed according to the second sensing line 22 . The difference between the voltage values or the difference between the values corresponding to the voltage signals of the first frequency f ₁ and the second frequency f2 of the conversion circuit 30 is the position of the interruption point.

A flowchart of a method for detecting whether the first sensing line 21 is open or not by the detecting circuit 1 of the present invention will be described below with reference to FIGS. Referring to Figure 7, the method includes:

Step S100, providing voltage signals of the first frequency f ₁ and the second frequency f ₂ having the same voltage value to the two ends of the first sensing line 21 . In the present embodiment, the first frequency f ₁ and the second frequency f ₂ are ₁₀₀ kHz and 150 kHz, respectively, and the voltage value is 1.0V.

Step S200, receiving a voltage signal outputted from the two sensing lines 22, and converting the output voltage signals corresponding to the voltage signals of the first frequency f ₁ and the second frequency f ₂ into a first value and a second value. In the present embodiment, the conversion circuit 30 is a 14-bit digital-to-analog converter.

Step S300, determining whether the absolute value of the difference between the first value and the second value is large Or equal to a preset value. When the absolute value of the difference between the first value and the second value is greater than or equal to the preset value, the process proceeds to step S400, when the absolute value of the difference between the first value and the second value is less than the preset When the value is reached, the process proceeds to step S500.

In step S400, the first sensing line 21 has an open circuit.

In step S500, the first sensing line 21 does not have an open circuit.

It is to be understood that the detection circuit 1 and the detection method of the present invention are described by taking the first sensing line 21 in the touch panel 2 as an example. The detection circuit 1 and the detection method of the present invention are also applicable to the second in the touch panel 2. Sensing line 22.

It can be understood that the detecting circuit 1 can be an integrated chip, and the test signal output terminal Vin and the signal receiving end Vout are respectively a detection signal output pin and a signal receiving pin of the integrated chip. The detection principle of the detection circuit 1 is described by taking a second sensing line 22 on the touch panel 2 as an example. All the second sensing lines 22 on the touch panel 2 are connected to a conversion circuit 30. The detection process of the second sensing line 22 and the conversion circuit is the same as the detection principle described above, and at this time, the detection result is more accurate.

Compared with the prior art, the detection circuit 1 of the present invention and the detection method using the detection circuit 1 provide voltage signals having different voltage values at the same frequency to the two first traces 23 of the first sensing line 21, and the first The voltage signals of the outputs of the two second traces 24 of the two senses 22 are converted to a first value and a second value. When the absolute value of the difference between the first value and the second value is greater than or equal to a predetermined value, the first sensing line is broken. By implementing the present invention, a more precise technical effect of judging whether the sensing line is broken or not is achieved.

Although the present invention has been disclosed above in the preferred embodiments, it is not intended to limit the present invention. Any changes that may be made in accordance with the spirit of the invention are intended to be included within the scope of the invention as claimed.

1‧‧‧Detection circuit

2‧‧‧ touch panel

10‧‧‧Test power supply

30‧‧‧Transition circuit

50‧‧‧Processing unit

Vin‧‧‧ test signal output

Vout‧‧‧ signal receiving end

21‧‧‧First sensing line

22‧‧‧Second sensing line

23‧‧‧First Trace

24‧‧‧Second Trace

21a‧‧‧The first sub-sensing line

21b‧‧‧Second sub-sensing line

D1‧‧‧ first direction

D2‧‧‧ second direction

P1, P2, Q‧‧‧ nodes

M‧‧‧ midpoint

D‧‧‧ Breakpoint

Claims (10)

A detecting circuit for detecting a sensing line of a touch panel, configured to detect whether a sensing line in the touch panel is broken, the sensing line comprising a plurality of first sensing lines extending in a first direction and a plurality of second extending in a second direction a sensing line, wherein each of the two sensing lines is electrically connected to a first trace, and each of the two sensing lines is electrically connected to a second trace, wherein the detecting circuit comprises a test power source. a conversion circuit and a processing unit, wherein the test power supply is configured to provide a voltage signal having equal voltage values and frequencies of a first frequency and a second frequency to the first trace, the first frequency being different from the second frequency, the conversion circuit And receiving, by the processing unit, a voltage signal outputted from the second trace and converting the first value and the second value, the processing unit comparing the difference between the first value and the second value, when the first value and the first value When the absolute value of the difference between the two values is greater than or equal to a predetermined value, the processing unit determines that the first sensing line is open. The detecting circuit of claim 1, wherein when the absolute value of the difference between the first value and the second value is less than the preset value, the processing unit determines that the first sensing line does not have an open circuit. The detection circuit of claim 1, wherein the test source has a voltage value of 1.0V. The detecting circuit of claim 1, wherein the first frequency is 100 kHz and the second frequency is 150 kHz. The detection circuit of claim 1, wherein the conversion circuit is a 14-bit digital-to-analog converter. A method for detecting a sensing line of a touch panel for detecting whether a sensing line in the touch panel is broken, the sensing line includes a plurality of first sensing lines extending in a first direction and a plurality of second extending in a second direction The sensing line is electrically connected to a first trace of each of the first sensing lines, and the two ends of each of the second sensing lines are electrically connected to a second trace, wherein the method comprises: Providing a voltage signal having the same voltage value and a frequency of the first frequency and the second frequency to the first trace, the first frequency being different from the second frequency; receiving the voltage signal output from the second trace and corresponding Converting to a first value and a second value; determining whether an absolute value of the difference between the first value and the second value is greater than or equal to a predetermined value; and a difference between the first value and the second value When the absolute value is greater than or equal to a preset value, the first sensing line is broken. The detecting method of claim 6, wherein when the absolute value of the difference between the first value and the second value is less than the preset value, the first sensing line does not have an open circuit. The detection method of claim 6, wherein the voltage signal has a voltage value of 1.0V. The detecting method of claim 6, wherein the first frequency is 100 kHz and the second frequency is 150 kHz. The detection method of claim 6, wherein the conversion circuit is a 14-bit digital-to-analog converter.