CN113868049A - Touch matrix repair circuit of capacitive touch screen - Google Patents
Touch matrix repair circuit of capacitive touch screen Download PDFInfo
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- G06F11/2205—Detection or location of defective computer hardware by testing during standby operation or during idle time, e.g. start-up testing using arrangements specific to the hardware being tested
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Abstract
The invention relates to the technical field of capacitive touch screen film testing, and discloses a capacitive touch screen touch matrix repair circuit and a capacitive touch screen touch matrix repair device, wherein the capacitive touch screen touch matrix repair circuit comprises a control module, a first-phase amplification circuit and a second-phase amplification circuit, wherein the control module is used for controlling a digital-to-analog conversion module, an in-phase amplification circuit and an anti-phase amplification circuit; the digital-to-analog conversion module is used for outputting a positive voltage signal and a negative voltage signal according to the control signal; the in-phase amplifying circuit is connected with the digital-to-analog conversion module and used for amplifying the positive electrode voltage signal and outputting a positive electrode pulse signal under the control of the control module; and the inverting amplifying circuit is connected with the digital-to-analog conversion module and used for amplifying the negative voltage signal and outputting a negative pulse signal under the control of the control module. The duty ratio and the high-voltage pulse with the adjustable period generated by the touch matrix repair circuit of the capacitive touch screen can be used for repairing burr short circuits of the capacitive touch screen caused by stone carving, and further the yield of customer products is improved.
Description
Technical Field
The invention relates to the technical field of capacitive touch screen film testing, in particular to a capacitive touch screen touch matrix repairing circuit and a capacitive touch screen touch matrix testing device.
Background
Currently, a common test scheme for the resistance-capacitance of the touch matrix of the capacitive touch screen is to use a TP test box to read some parameters of the capacitive touch screen. However, the TP test box obtains parameters such as RAW data, open/short, point coordinates and the like through communication between I2C or SPI and a TP dedicated chip, so that it cannot actively repair a burr short circuit caused by a stone etching process between adjacent points of a touch screen matrix, thereby reducing the yield of products of module manufacturers and causing huge loss.
Disclosure of Invention
Therefore, it is necessary to provide a repair circuit and a test device for a touch matrix of a capacitive touch screen, which are used for solving the problem that the existing test method cannot repair a defective module to be tested.
A touch matrix repair circuit of a capacitive touch screen comprises a digital-to-analog conversion module, an in-phase amplification circuit, an anti-phase amplification circuit and a control module, wherein the control module is respectively connected with the digital-to-analog conversion module, the in-phase amplification circuit and the anti-phase amplification circuit and used for outputting a control signal to the digital-to-analog conversion module; the digital-to-analog conversion module is used for outputting a positive voltage signal and a negative voltage signal according to the control signal; the in-phase amplifying circuit is respectively connected with the positive ends of the digital-to-analog conversion module and the touch matrix circuit and is used for amplifying the positive voltage signal under the control of the control module to generate a positive pulse signal; and the reverse-phase amplifying circuit is respectively connected with the digital-to-analog conversion module and the negative end of the touch matrix circuit and is used for amplifying the negative voltage signal under the control of the control module to generate a negative pulse signal.
According to the touch matrix repairing circuit of the capacitive touch screen, the control module is used for controlling the digital-to-analog conversion module, the in-phase amplifying circuit and the reverse-phase amplifying circuit, and the control module outputs a control signal to the digital-to-analog conversion module. The digital-to-analog conversion module outputs a positive voltage signal and a negative voltage signal according to the control signal. The in-phase amplification circuit amplifies the positive electrode voltage signal and generates a positive electrode pulse signal under the control of the control module, and the reverse-phase amplification circuit amplifies the negative electrode voltage signal and generates a negative electrode pulse signal under the control of the control module. The duty ratio and the high-voltage pulse with the adjustable period generated by the touch matrix repair circuit of the capacitive touch screen can be used for repairing burr short circuits of the capacitive touch screen caused by stone carving, and further the yield of customer products is improved.
In one embodiment, the digital-to-analog conversion module includes a digital-to-analog conversion unit and a first operational amplifier, an output end of the digital-to-analog conversion unit is connected to a non-inverting input end of the first operational amplifier, and an inverting input end of the digital-to-analog conversion unit is connected to an inverting output end of the first operational amplifier.
In one embodiment, the digital-to-analog conversion module further includes a first capacitor, a first end of the first capacitor is connected to the inverting input terminal of the first operational amplifier, a second end of the first capacitor is connected to the output terminal of the first operational amplifier, and a second end of the first capacitor is further connected to the feedback signal input terminal of the digital-to-analog conversion unit.
In one embodiment, the touch matrix repair circuit for the capacitive touch screen further includes a reference voltage module connected to the digital-to-analog conversion module and configured to provide a reference voltage to the digital-to-analog conversion module.
In one embodiment, the non-inverting amplifying circuit includes a second operational amplifier, a first resistor, and a second resistor, a non-inverting input terminal of the second operational amplifier is connected to the output terminal of the digital-to-analog conversion module, an inverting input terminal of the second operational amplifier is connected to a first terminal of the first resistor, a second terminal of the first resistor is grounded, a first terminal of the second resistor is connected to the inverting input terminal of the second operational amplifier, and a second terminal of the second resistor is connected to the output terminal of the second operational amplifier.
In one embodiment, the non-inverting amplifier circuit further includes a third operational amplifier, a non-inverting input of the third operational amplifier is connected to the output of the second operational amplifier, an inverting input of the third operational amplifier is connected to the output of the third operational amplifier, and the output of the third operational amplifier is connected to the output of the second operational amplifier.
In one embodiment, the in-phase amplifying circuit further includes a third resistor, a fourth resistor, and a fifth resistor, a first end of the third resistor is connected to the non-inverting input terminal of the second operational amplifier, and a second end of the third resistor is connected to the output terminal of the digital-to-analog conversion module; a first end of the fourth resistor is connected with an output end of the second operational amplifier, and a second end of the fourth resistor is connected with a second end of the second resistor; the first end of the fifth resistor is connected with the output end of the third operational amplifier, and the second end of the fifth resistor is connected with the second end of the second resistor.
In one embodiment, the inverting amplifying circuit includes a fourth operational amplifier, a sixth resistor, and a seventh resistor, an inverting input terminal of the fourth operational amplifier is connected to a first terminal of the sixth resistor, a second terminal of the sixth resistor is connected to an output terminal of the digital-to-analog conversion module, a non-inverting input terminal of the fourth operational amplifier is grounded, a first terminal of the seventh resistor is connected to an inverting input terminal of the fourth operational amplifier, and a second terminal of the seventh resistor is connected to an output terminal of the fourth operational amplifier.
In one embodiment, the inverting amplifier circuit further includes a fifth operational amplifier, a non-inverting input terminal of the fifth operational amplifier is connected to the output terminal of the fourth operational amplifier, an inverting input terminal of the fifth operational amplifier is connected to the output terminal of the fifth operational amplifier, and an output terminal of the fifth operational amplifier is connected to the second terminal of the seventh resistor.
In one embodiment, the inverting amplifying circuit further includes an eighth resistor and a ninth resistor, a first end of the eighth resistor is connected to the output end of the fourth operational amplifier, and a second end of the eighth resistor is connected to the second end of the seventh resistor; a first end of the ninth resistor is connected to an output end of the fifth operational amplifier, and a second end of the ninth resistor is connected to a second end of the seventh resistor.
In one embodiment, the capacitive touch screen touch matrix repair circuit further includes a switch module, which is respectively connected to the in-phase amplification circuit, the reverse-phase amplification circuit and the control module, and is configured to control on/off of connection between the in-phase amplification circuit and a positive terminal of the touch matrix according to a switch instruction of the control module, and/or control on/off of connection between the reverse-phase amplification circuit and a negative terminal of the touch matrix according to a switch instruction of the control module.
Drawings
In order to more clearly illustrate the embodiments of the present specification or the technical solutions in the prior art, the drawings needed to be used in the description of the embodiments or the prior art will be briefly introduced below, it is obvious that the drawings in the following description are only some embodiments described in the specification, and other drawings can be obtained by those skilled in the art without inventive labor.
Fig. 1 is a block diagram of a touch matrix repair circuit of a capacitive touch screen according to an embodiment of the disclosure;
fig. 2 is a schematic circuit connection diagram of a touch matrix repair circuit of a capacitive touch screen according to an embodiment of the disclosure;
fig. 3 is a waveform diagram of a bipolar pulse signal according to an embodiment of the disclosure.
Detailed Description
To facilitate an understanding of the invention, the invention will now be described more fully with reference to the accompanying drawings. Preferred embodiments of the present invention are shown in the drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete.
It will be understood that when an element is referred to as being "secured to" another element, it can be directly on the other element or intervening elements may also be present. When an element is referred to as being "connected" to another element, it can be directly connected to the other element or intervening elements may also be present. As used herein, the terms "vertical," "horizontal," "left," "right," "upper," "lower," "front," "rear," "circumferential," and the like are based on the orientation or positional relationship shown in the drawings for ease of description and simplicity of description, and do not indicate or imply that the referenced device or element must have a particular orientation, be constructed and operated in a particular orientation, and are therefore not to be considered limiting of the present invention.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.
At present, some domestic factories can read some parameters of the capacitive touch screen by using a scheme of the TP test box, but the TP test box cannot repair a defective module, and the module with the defect can cause the loss of a module manufacturer. Therefore, the test box with the function of repairing the short circuit of the touch matrix in the capacitive touch screen has great commercial value.
Fig. 1 is a block diagram of a capacitive touch screen touch matrix repair circuit according to an embodiment of the disclosure, in which in an embodiment, a capacitive touch screen touch matrix repair circuit 10 is used to repair a short circuit burr in a touch matrix circuit. The touch matrix repair circuit 10 of the capacitive touch screen may include a digital-to-analog conversion module 100, an in-phase amplification circuit 200, an inverse amplification circuit 300, and a control module 400.
The control module 400 is respectively connected to the digital-to-analog conversion module 100, the in-phase amplifying circuit 200 and the inverting amplifying circuit 300, and the control module 400 can be used to output a control signal to the digital-to-analog conversion module 100.
The digital-to-analog conversion module 100 may output a positive voltage signal and a negative voltage signal according to the control signal. The method for repairing the short-circuit fault in the touch matrix circuit of the capacitive touch screen can utilize positive and negative high-voltage pulses to be applied to the position of a matrix point with the short-circuit fault, so that the matrix point is fused due to the large current passing instantly. The range of the voltage amplitude that can be output by the digital-to-analog converter is ± 5V, however, the voltage that can be used for fusing the short-circuit fault generally needs ± 30V, and the specific value can be determined according to the value of the power supply voltage, and is not limited herein. It can be seen that the amplitude of the voltage signal that the digital-to-analog conversion module 100 can output is generally small, and is not enough to blow the short-circuit fault. At this time, the voltage values of the positive and negative voltage signals output by the digital-to-analog conversion module 100 may be amplified by the amplifying circuit. The in-phase amplifying circuit 200 is connected to the digital-to-analog converting module 100, and can amplify the positive voltage signal. The inverting amplifier circuit 300 is connected to the digital-to-analog conversion module 100, and may amplify the negative voltage signal.
The burr short-circuit processing method can be processed by a continuous large current or an intermittent large current. The capacitive touch screen has the advantages that the burr short circuit of the touch matrix of the capacitive touch screen is relatively small, the capacitive touch screen can be fused without continuous current, the continuous high voltage and the continuous high current can burn off the capacitive touch screen, and therefore the short circuit of the touch matrix in the capacitive touch screen can be repaired safely by adopting the controllable discontinuous high current.
The control module 400 can be used to control the operating state of the in-phase amplifying circuit 200, so that the in-phase amplifying circuit 200 outputs a pulse waveform signal. The input end of the in-phase amplifying circuit 200 is connected to the output end of the digital-to-analog conversion module 100, and is configured to amplify the positive voltage signal. The output end of the in-phase amplifying circuit 200 is connected to the positive end of the touch matrix circuit, and the in-phase amplifying circuit 200 can output a positive pulse signal to the positive end of the touch matrix circuit under the control of the control module 400.
The control module 400 can be used to control the operating state of the inverting amplifier circuit 300, so that the inverting amplifier circuit 300 outputs a pulse waveform signal. The input end of the inverting amplifier circuit 300 is connected to the output end of the digital-to-analog conversion module 100, and is configured to amplify the negative voltage signal. The output terminal of the inverting amplifier circuit 300 is connected to the negative terminal of the touch matrix circuit, and the inverting amplifier circuit 300 can output a negative pulse signal to the negative terminal of the touch matrix circuit under the control of the control module 400.
The bipolar pulse signal output by the matrix repair circuit 10 includes a positive pulse signal output by the in-phase amplification circuit 200 and a negative pulse signal output by the reverse-phase amplification circuit 300. The control module 400 can adjust the duty ratio and the period of the bipolar pulse signal by changing the working state of the in-phase amplification circuit 200 and/or the anti-phase amplification circuit 300, and can simultaneously set the amplitude of the pulse signal by changing the DAC 110. It can be seen that, the capacitive touch screen touch matrix repair circuit 10 may output a high-voltage bipolar pulse signal with a controllable duty ratio and period and an amplitude of the pulse signal, instead of outputting a dc voltage, by controlling each functional module with the control module 400.
In some embodiments of the present disclosure, the control module 400 controls each functional module, and the bipolar pulse signal output by the capacitive touch screen touch matrix repair circuit 10 is a square wave signal. In some other embodiments, the control signal of the control module 400 may also be adjusted according to a specific practical application requirement, so that the bipolar pulse signal output by the capacitive touch screen touch matrix repair circuit 10 is a signal with any other waveform, such as a triangular wave, a trapezoidal wave, a sharp pulse, and the like, which is not limited herein.
The capacitive touch screen touch matrix repair circuit 10 is added in a test box for a touch matrix in a capacitive touch screen, when a short-circuit fault exists in the touch matrix, the capacitive touch screen touch matrix repair circuit 10 can output a high-voltage bipolar pulse signal with adjustable duty ratio and period, and the high-voltage bipolar pulse signal is applied to a matrix point position with the short-circuit fault, so that burr short circuit caused in a stone etching process in the capacitive touch screen can be repaired, and the yield of a customer product is improved.
Because two maximum pulse voltages which can be output by the capacitive touch screen touch matrix repair circuit 10 provided in some embodiments of the present disclosure can be set to ± 30V, if a bipolar pulse voltage with a voltage amplitude of 30V is directly applied, a very large instantaneous current is generated at the moment of short circuit, and for a power supply of the capacitive touch screen touch matrix repair circuit, the instantaneous current is also an impact, and the larger the impact, the larger the damage probability to the power supply is. Therefore, in some embodiments of the present disclosure, the voltage amplitude of the bipolar pulse signal output by the capacitive touch screen touch matrix repair circuit 10 may be set according to the amount of the short circuit glitch.
For example, when repairing a target module glitch short circuit, a bipolar pulse voltage with a smaller voltage amplitude may be applied to the target module, and if the bipolar pulse voltage with the voltage amplitude cannot smoothly fuse the glitch short circuit, the voltage amplitude of the bipolar pulse voltage may be appropriately increased until the glitch short circuit is fused. Whether the short circuit burrs in the target module are fused or not can be judged by testing the equivalent values of insulation resistance and mutual capacitance of the touch screen matrix.
Fig. 2 is a circuit connection diagram of a touch matrix repair circuit of a capacitive touch screen according to an embodiment of the disclosure, in which in an embodiment, the digital-to-analog conversion module 100 may include a digital-to-analog conversion unit 110 and a first operational amplifier 120. In some embodiments of the present disclosure, the digital-to-Analog conversion unit 110 includes a digital-to-Analog converter (dac), which is a device for converting digital quantity into Analog quantity. As shown in fig. 2, the output terminal of the digital-to-analog conversion unit 110 is connected to the non-inverting input terminal of the first operational amplifier 120, and the inverting input terminal of the digital-to-analog conversion unit 110 is connected to the inverting output terminal of the first operational amplifier 120.
The digital-to-analog converter DAC is typically made up of 4 parts including a weighted resistor network, an operational amplifier, a reference supply, and an analog switch. The Vout output pin of the DAC is connected to the non-inverting input of the first operational amplifier 120, and the INV pin of the DAC is connected to the inverting input of the first operational amplifier 120. The INV pin is a center tap of a scaling resistor inside the digital-to-analog converter DAC and is connected with an inverting input end of an external operational amplifier when the digital-to-analog converter DAC operates in a bipolar mode.
In one embodiment, the control module 400 is a master controller MCU (Microcontroller Unit) of a system board. The main controller MCU may send an output command to the digital-to-analog conversion unit 110 through a Serial Peripheral Interface (SPI), so as to control the digital-to-analog conversion unit 110 to output a bipolar voltage signal. In some embodiments of the present disclosure, the digital-to-analog conversion unit 110 is a DAC chip with a Bipolar Mode (Bipolar operating Mode) output. The digital-to-analog conversion unit 110, in cooperation with the first operational amplifier 120, can output a bipolar pulse signal with a swing range of-VREF to + VREF.
The control module 400 transmits the output command of the digital signal to the digital-to-analog conversion unit 110 through the serial peripheral interface SPI, and stores the output command in the digital register of the digital-to-analog conversion unit 110. The digital-to-analog conversion unit 110 decodes the digital signal, i.e., converts the digital code into a level corresponding thereto to form a staircase signal, and then performs low-pass filtering. Each digit output by the digital register respectively controls the analog electronic switches of the corresponding digit, so that the digit with the digit number of 1 generates a current value which is in direct proportion to the weight value on a weight network, and then the summing circuit adds the weight values to obtain the analog quantity corresponding to the digital quantity.
In this embodiment, the digital-to-analog conversion unit 110 is connected to the first operational amplifier 120, and can be used to output an adjustable bipolar voltage signal. Meanwhile, because a plurality of high-frequency components are mixed in the output signal just converted by the digital-to-analog conversion unit 110, the output signal cannot be directly used for power output, otherwise, the excessive high-frequency signal causes the power tube to generate heat and increase power consumption. The digital-to-analog conversion unit 110 and the first operational amplifier 120 may be connected to form a Low-pass filter (LPF) circuit, which is used to remove a high frequency portion of the output signal of the digital-to-analog conversion unit 110, so as to improve the signal-to-noise ratio of the useful signal and reduce useless power consumption.
The bipolar voltage signals output by the digital-to-analog conversion module 100 are respectively transmitted to the in-phase amplification circuit 200 and the reverse-phase amplification circuit 300, and the two amplification circuits are used for respectively amplifying the bipolar voltage signals. The two amplification circuits may perform amplification on the bipolar voltage signal including, but not limited to, 10 times amplification. In some embodiments of the present disclosure, the amplification gains of the two amplification circuits may be adjusted according to practical applications, so as to perform different degrees of signal amplification on the bipolar voltage signal.
In one embodiment, the digital-to-analog conversion module 100 may further include a first capacitor 130. A first terminal of the first capacitor 130 is connected to the inverting input terminal of the first operational amplifier 120, and a second terminal of the first capacitor 130 is connected to the output terminal of the first operational amplifier 120. The second end of the first capacitor 130 is also connected to the feedback signal input end R of the digital-to-analog conversion unit 110FBAre connected. RFBThe pin is connected with a feedback resistor inside the digital-to-analog conversion unit 110, and the digital-to-analog conversion unit 110 operates in a bipolar modeFBThe pin is connected to the output terminal of the external amplifier, and the bipolar output range of the digital-to-analog conversion unit 110 operating in the bipolar mode is-VREF to VREF.
The first capacitor 130 functions as a feedback capacitor in the digital-to-analog conversion module 100, and is used for providing a zero compensation to the digital-to-analog conversion unit 110, so as to improve the phase margin of the output signal of the digital-to-analog conversion unit 110. In some embodiments of the present disclosure, the first capacitor 130 has a value ranging from 5pF to 10 pF.
In one embodiment, the touch matrix repair circuit 10 of the capacitive touch screen may further include a reference voltage module 500, connected to the digital-to-analog conversion module 100, for providing a reference voltage to the digital-to-analog conversion module 100. The reference voltage module 500 is used as a reference power source to connect to the Vref pin of the dac unit 110. The reference voltage module 500 inputs a reference voltage to the digital-to-analog conversion unit 110, and the digital-to-analog conversion unit 110 compares the reference voltage with the generated analog signal as a reference for successive approximation.
In some embodiments of the present disclosure, a voltage reference source chip is used as the reference voltage module 500 to provide a precise reference voltage to the digital-to-analog conversion unit 110. In some other embodiments, when the capacitive touch screen touch matrix repair circuit 10 does not need to output a particularly accurate voltage, the reference voltage pin of the digital-to-analog conversion unit 110 may be directly connected to the power supply voltage of the digital-to-analog conversion unit 110 without using a voltage reference source chip as a reference source, so that the cost of one reference chip may be saved.
In one embodiment, the non-inverting amplifier circuit 200 may include a second operational amplifier 210, a first resistor 220, and a second resistor 230. In some embodiments of the present disclosure, an operational amplifier element having a high supply voltage and a high output current is employed as the second operational amplifier 210.
The non-inverting input terminal of the second operational amplifier 210 is connected to the output terminal of the first operational amplifier 120 in the digital-to-analog conversion module 100, and the bipolar voltage signal output by the first operational amplifier 120 is transmitted to the second operational amplifier 210. The inverting input terminal of the second operational amplifier 210 is connected to the first terminal of the first resistor 220, and the second terminal of the first resistor 220 is grounded. A first terminal of the second resistor 230 is connected to the inverting input terminal of the second operational amplifier 210, and a second terminal of the second resistor 230 is connected to the output terminal of the second operational amplifier 210. If the resistance of the first resistor 220 is denoted as R1 and the resistance of the second resistor 230 is denoted as R2, the gain of the in-phase amplifier circuit 200 is calculated as follows: g ═ 1+ (R2/R1). In practical applications, the resistances of the first resistor 220 and the second resistor 230 may be designed according to practical requirements, and the amplification gain of the in-phase amplifier circuit 200 is set by changing the resistances of the first resistor 220 and the second resistor 230.
In one embodiment, the in-phase amplifying circuit 200 may further include a third operational amplifier 240. The non-inverting input terminal of the third operational amplifier 240 is connected to the output terminal of the second operational amplifier 210, the inverting input terminal of the third operational amplifier 240 is connected to the output terminal of the third operational amplifier 240, and the output terminal of the third operational amplifier 240 is connected to the second terminal of the second resistor 230. In some embodiments of the present disclosure, the same operational amplifier element as the second operational amplifier 210 is employed as the third operational amplifier 240.
The third operational amplifier 240 is connected to the output end of the second operational amplifier 210, and can be used as a first-stage follower of the second operational amplifier 210 for improving the capability of the second operational amplifier 210 to output current. When repairing the burr short circuit caused by the stone carving process in the production process of the capacitive touch screen, the short circuit burr needs to be fused by using a large current, so that the capacity of outputting current by the second operational amplifier 210 is improved through the third operational amplifier 240, the current of the output signal of the in-phase amplification circuit 200 can be improved, and the repair efficiency of the short circuit burr is improved.
In one embodiment, the in-phase amplifying circuit 200 may further include a third resistor 250, a fourth resistor 260, and a fifth resistor 270.
The first end of the third resistor 250 is connected to the non-inverting input terminal of the second operational amplifier 210, the second end of the third resistor 250 is connected to the output terminal of the first operational amplifier 120 in the digital-to-analog conversion module 100, and since the inverting amplifier circuit 300 is connected to a resistor at the inverting input terminal for adjusting the amplification gain of the inverting amplifier circuit 300, in order to balance the impedance of the input terminals, a resistor may also be connected to the non-inverting input terminal of the second operational amplifier 210, and the third resistor 250 plays a role of resistance matching in the non-inverting amplifier circuit 200. In some embodiments of the present disclosure, the value of the third resistor 250 may be 100 Ω. Since the input impedance of the operational amplifier in the non-inverting amplifier circuit 200 is usually in the order of mega-ohm, the third resistor 250 with smaller resistance is added to the non-inverting input terminal of the second operational amplifier 210, and the influence on the circuit gain is negligible.
A first terminal of the fourth resistor 260 is connected to the output terminal of the second operational amplifier 210, and a second terminal of the fourth resistor 260 is connected to a second terminal of the second resistor 230. The fourth resistor 260 is used in the non-inverting amplifier circuit 200 as an output current limiting resistor of the second operational amplifier 210. In some embodiments of the present disclosure, a resistor of 10 Ω and a power of 1W or more may be used as the fourth resistor 260.
The output of the second operational amplifier 210 is connected to a high power fourth resistor 260, which may be used for current limiting. Since the output of the second operational amplifier 210 is directly connected to the matrix point of the touch matrix in the capacitive touch screen through the relay, when two high voltages, positive and negative, are applied to the short circuit line of the matrix point, a large current will be generated instantaneously, and therefore a resistor with large power needs to be added to protect the second operational amplifier 210, thereby preventing the second operational amplifier 210 from being damaged due to the large current.
A first terminal of the fifth resistor 270 is connected to the output terminal of the third operational amplifier 240, and a second terminal of the fifth resistor 270 is connected to the second terminal of the second resistor 230. Similarly, the fifth resistor 270 is used in the non-inverting amplifier circuit 200 as an output current limiting resistor of the third operational amplifier 240. In some embodiments of the present disclosure, a resistor having the same value as the fourth resistor 260 is used as the fifth resistor 270. The output of the third operational amplifier 240 is also connected to a high power fifth resistor 270, which may be used for current limiting. Since the output of the third operational amplifier 240 is directly connected to the matrix point of the capacitive touch screen through the relay, a resistor with high power is also required to protect the third operational amplifier 240, thereby preventing the third operational amplifier 240 from being damaged due to high current.
In one embodiment, the inverting amplifier circuit 300 includes a fourth operational amplifier 310, a sixth resistor 320, and a seventh resistor 330. In some embodiments of the present disclosure, an operational amplifier element having a high supply voltage and a high output current is employed as the fourth operational amplifier 310.
The inverting input terminal of the fourth operational amplifier 310 is connected to the first terminal of the sixth resistor 320, the second terminal of the sixth resistor 320 is connected to the output terminal of the first operational amplifier 120 in the digital-to-analog conversion module 100, and the bipolar pulse signal output by the first operational amplifier 120 is transmitted to the fourth operational amplifier 310. The magnitude of the sixth resistor 320 may affect the amplification gain error of the inverting amplifier circuit 300, and the value of the sixth resistor 320 is usually 100 Ω.
The non-inverting input of the fourth operational amplifier 310 is grounded, the first terminal of the seventh resistor 330 is connected to the inverting input of the fourth operational amplifier 310, and the second terminal of the seventh resistor 330 is connected to the output of the fourth operational amplifier 310. The resistance of the sixth resistor 320 is denoted as R4, the resistance of the seventh resistor 330 is denoted as R5, and the gain of the inverting amplifier circuit 300 is calculated by: g ═ - (R5/R4). In practical applications, the resistances of the sixth resistor 320 and the seventh resistor 330 may be designed according to practical requirements, and the amplification gain of the in-phase amplifier circuit 200 is set by changing the resistances of the sixth resistor 320 and the seventh resistor 330.
In one embodiment, the inverting amplifying circuit 300 may further include a fifth operational amplifier 340, a non-inverting input terminal of the fifth operational amplifier 340 is connected to the output terminal of the fourth operational amplifier 310, an inverting input terminal of the fifth operational amplifier 340 is connected to the output terminal of the fifth operational amplifier 340, and an output terminal of the fifth operational amplifier 340 is connected to the second terminal of the seventh resistor 330. In some embodiments of the present disclosure, the same operational amplifier element as the fourth operational amplifier 310 may also be employed as the fifth operational amplifier 340.
The fifth operational amplifier 340 is connected to the output terminal of the fourth operational amplifier 310, and can be used as a first-stage follower of the fourth operational amplifier 310 for improving the capability of the fourth operational amplifier 310 to output current. Similarly, when a burr short circuit caused by a stone etching process in the production process of the capacitive touch screen is repaired, the short circuit burr needs to be fused by using a large current, so that the capability of outputting a current by the fourth operational amplifier 310 is improved by the fifth operational amplifier 340, and the current of an output signal of the inverting amplifier circuit 300 can be improved, so that the repair efficiency of the short circuit burr is improved.
In one embodiment, the inverting amplifier circuit 300 may further include an eighth resistor 350 and a ninth resistor 360.
A first terminal of the eighth resistor 350 is connected to the output terminal of the fourth operational amplifier 310, and a second terminal of the eighth resistor 350 is connected to a second terminal of the seventh resistor 330. The eighth resistor 350 is used in the non-inverting amplifier circuit 200 as an output current limiting resistor of the fourth operational amplifier 310. In some embodiments of the present disclosure, a resistor of 10 Ω and a power of 1W or more may be used as the eighth resistor 350.
The output of the fourth operational amplifier 310 is connected to a high power eighth resistor 350 for current limiting. Because the output of the fourth operational amplifier 310 is directly connected to the matrix point of the touch matrix in the capacitive touch screen through the relay, when two positive and negative high voltages are applied to the short circuit line of the matrix point, a large current will be generated instantaneously, and therefore a resistor with large power needs to be added to protect the fourth operational amplifier 310, and the fourth operational amplifier 310 is prevented from being damaged by the large current.
A first terminal of the ninth resistor 360 is connected to the output terminal of the fifth operational amplifier 340, and a second terminal of the ninth resistor 360 is connected to a second terminal of the seventh resistor 330. Similarly, the ninth resistor 360 is used as an output current limiting resistor of the fifth operational amplifier 340 in the in-phase amplifying circuit 200. In some embodiments of the present disclosure, a resistor having the same value as the eighth resistor 350 is used as the ninth resistor 360.
The output of the fifth operational amplifier 340 is also connected to a high power ninth resistor 360, which may be used for current limiting. Since the output of the fifth operational amplifier 340 is directly connected to the matrix point of the capacitive touch screen through the relay, a resistor with large power is also required to protect the fifth operational amplifier 340, thereby preventing the fifth operational amplifier 340 from being damaged by large current.
In one embodiment, the capacitive touch screen touch matrix repair circuit 10 further includes a switch module 600, which is respectively connected to the in-phase amplification circuit 200, the reverse-phase amplification circuit 300 and the control module 400, and is configured to control on/off of a connection between the in-phase amplification circuit 200 and a positive terminal of the touch matrix circuit according to a switch instruction of the control module 400, and/or control on/off of a connection between the reverse-phase amplification circuit and a negative terminal of the touch matrix circuit according to a switch instruction of the control module 400.
In some embodiments of the present disclosure, the switch module 600 includes a first relay and a second relay. In some embodiments of the present disclosure, a double pole double throw relay may be employed as the first relay and the second relay.
A common connection point of the second terminal of the third resistor 250, the second terminal of the fourth resistor 260, and the second terminal of the fifth resistor 270 in the non-inverting amplifier circuit 200 is connected to the common terminal COM _ P through a first relay, and a common connection point of the second terminal of the seventh resistor 330, the second terminal of the eighth resistor 350, and the second terminal of the ninth resistor 360 in the inverting amplifier circuit 300 is connected to the common terminal COM _ N through a second relay. The common terminal COM _ P may be a positive terminal of the touch matrix circuit, and COM _ N may be a negative terminal of the touch matrix circuit.
The control module 400 may control the positive and negative two pulse waveforms output from the in-phase amplification circuit 200 and the reverse-phase amplification circuit 300 to be applied to the common terminals COM _ P and COM _ N by controlling the switches of the first relay and/or the second relay. The touch matrix circuit can transmit positive and negative pulse waveforms to a matrix column of the capacitive touch screen by switching an internal analog switch, so that a circuit part with a short-circuit fault in a fusing matrix is completed.
In some embodiments of the disclosure, the control instruction output by the control module 400 may be the enable signal EN. The control module 400 controls the outputs of the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310 and the fifth operational amplifier 340 by changing the enable signal EN output to the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310 and the fifth operational amplifier 340, so as to control the duty cycle and the period of the bipolar pulse signal finally output by the capacitive touch screen touch matrix repair circuit 10.
For example, the control module 400 controls turning on a first relay and a second relay. At time t0, the control module 400 applies an enable signal EN to the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310, and the fifth operational amplifier 340 to enable the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310, and the fifth operational amplifier 340 to output signals, and enter a normal operating state, so that the capacitive touch screen touch matrix repair circuit 10 outputs bipolar pulse signals to the common terminals COM _ P and COM _ N.
At time t1, the control module 400 controls the open enable signal EN so that the second, third, fourth and fifth operational amplifiers 210, 240, 310 and 340 will not output, thereby making the voltage on the common terminals COM _ P and COM _ N0. That is, the control module 400 controls the bipolar pulse signals to which the common terminals COM _ P and COM _ N are applied for (t1-t0) time.
At time t2, the control module 400 controls the application of the enable signal EN to the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310, and the fifth operational amplifier 340 again, so that the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310, and the fifth operational amplifier 340 can have signals output, and enter a normal operating state. That is, the control module 400 controls the electrical signal lasting for (t2-t1) time in the duty cycle of the capacitive touch screen touch matrix repair circuit 10 to be "0". By repeating the above control process, the capacitive touch screen touch matrix repair circuit 10 outputs a waveform with a period of (t2-t0), the duration of the bipolar voltage is (t1-t0), the duration of the output voltage is 0 is (t2-t1), and the waveform is as shown in fig. 3, where fig. 3 is a waveform diagram of a bipolar pulse signal according to an embodiment of the present disclosure. In fig. 3, the first waveform is a waveform of the positive pulse signal, and the second waveform is a waveform of the negative pulse signal. The upper edge of the positive pulse signal has a value of the amplification gain of the second operational amplifier 210 multiplied by + VREF, and the upper edge of the positive pulse signal has a value of the amplification gain of the fourth operational amplifier 310 multiplied by-VREF.
In one embodiment, the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310 and the fifth operational amplifier 340 may be powered by two power sources, and an operating voltage of, for example, ± 30V, may be applied to the second operational amplifier 210, the third operational amplifier 240, the fourth operational amplifier 310 and the fifth operational amplifier 340. The magnitude of the applied voltage can be adjusted appropriately within a range of ± 30V, which is not limited herein.
In summary, the touch matrix repair circuit 10 of the capacitive touch screen is mainly used for repairing a short circuit between adjacent matrix points in a touch matrix of the capacitive touch screen. When the capacitive touch screen is tested, the high-voltage pulse with adjustable duty ratio, period and voltage amplitude generated by the capacitive touch screen touch matrix repair circuit 10 can be used for repairing burr short circuit caused by a stone etching process in the capacitive touch screen, and meanwhile, the voltage value can be adjusted according to different burr conditions, so that burrs can be repaired accurately and effectively, and the yield of customer products is improved.
In the description herein, references to the description of "some embodiments," "other embodiments," "desired embodiments," etc., mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the invention. In this specification, a schematic description of the above terminology may not necessarily refer to the same embodiment or example.
The technical features of the embodiments described above may be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the embodiments described above are not described, but should be considered as being within the scope of the present specification as long as there is no contradiction between the combinations of the technical features.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (11)
1. A touch matrix repair circuit of a capacitive touch screen is characterized by comprising a digital-to-analog conversion module, an in-phase amplification circuit, an anti-phase amplification circuit and a control module,
the control module is respectively connected with the digital-to-analog conversion module, the in-phase amplifying circuit and the reverse-phase amplifying circuit and is used for outputting a control signal to the digital-to-analog conversion module;
the digital-to-analog conversion module is used for outputting a positive voltage signal and a negative voltage signal according to the control signal;
the in-phase amplifying circuit is respectively connected with the positive ends of the digital-to-analog conversion module and the touch matrix circuit and is used for amplifying the positive voltage signal under the control of the control module to generate a positive pulse signal;
the inverting amplifying circuit is respectively connected with the digital-to-analog conversion module and the negative end of the touch matrix circuit, and is used for amplifying the negative voltage signal under the control of the control module to generate a negative pulse signal.
2. The touch matrix repair circuit of claim 1, wherein the digital-to-analog conversion module comprises a digital-to-analog conversion unit and a first operational amplifier, an output terminal of the digital-to-analog conversion unit is connected to a non-inverting input terminal of the first operational amplifier, and an inverting input terminal of the digital-to-analog conversion unit is connected to an inverting output terminal of the first operational amplifier.
3. The touch matrix repair circuit for the capacitive touch screen according to claim 2, wherein the digital-to-analog conversion module further includes a first capacitor, a first end of the first capacitor is connected to the inverting input terminal of the first operational amplifier, a second end of the first capacitor is connected to the output terminal of the first operational amplifier, and a second end of the first capacitor is further connected to the feedback signal input terminal of the digital-to-analog conversion unit.
4. The touch matrix repair circuit for a capacitive touch screen according to claim 1 or 2, further comprising a reference voltage module connected to the digital-to-analog conversion module for providing a reference voltage to the digital-to-analog conversion module.
5. The touch matrix repair circuit of claim 1, wherein the in-phase amplifier circuit comprises a second operational amplifier, a first resistor and a second resistor,
the non-inverting input end of the second operational amplifier is connected with the output end of the digital-to-analog conversion module, the inverting input end of the second operational amplifier is connected with the first end of the first resistor, the second end of the first resistor is grounded, the first end of the second resistor is connected with the inverting input end of the second operational amplifier, and the second end of the second resistor is connected with the output end of the second operational amplifier.
6. The touch matrix repair circuit of claim 5, wherein the in-phase amplifier circuit further comprises a third operational amplifier, the in-phase input terminal of the third operational amplifier is connected to the output terminal of the second operational amplifier, the inverting input terminal of the third operational amplifier is connected to the output terminal of the third operational amplifier, and the output terminal of the third operational amplifier is connected to the output terminal of the second operational amplifier.
7. The touch matrix repair circuit of claim 6, wherein the in-phase amplifier circuit further comprises a third resistor, a fourth resistor, and a fifth resistor,
the first end of the third resistor is connected with the non-inverting input end of the second operational amplifier, and the second end of the third resistor is connected with the output end of the digital-to-analog conversion module;
a first end of the fourth resistor is connected with an output end of the second operational amplifier, and a second end of the fourth resistor is connected with a second end of the second resistor;
the first end of the fifth resistor is connected with the output end of the third operational amplifier, and the second end of the fifth resistor is connected with the second end of the second resistor.
8. The touch matrix repair circuit of claim 1, wherein the inverting amplifier circuit comprises a fourth operational amplifier, a sixth resistor and a seventh resistor,
the inverting input end of the fourth operational amplifier is connected with the first end of the sixth resistor, the second end of the sixth resistor is connected with the output end of the digital-to-analog conversion module, the non-inverting input end of the fourth operational amplifier is grounded, the first end of the seventh resistor is connected with the inverting input end of the fourth operational amplifier, and the second end of the seventh resistor is connected with the output end of the fourth operational amplifier.
9. The touch matrix repair circuit of claim 8, wherein the inverting amplifier circuit further comprises a fifth operational amplifier, a non-inverting input of the fifth operational amplifier is connected to an output of the fourth operational amplifier, an inverting input of the fifth operational amplifier is connected to an output of the fifth operational amplifier, and an output of the fifth operational amplifier is connected to a second terminal of the seventh resistor.
10. The capacitive touch screen touch matrix repair circuit of claim 9, wherein the inverting amplifier circuit further comprises an eighth resistor and a ninth resistor,
a first end of the eighth resistor is connected with an output end of the fourth operational amplifier, and a second end of the eighth resistor is connected with a second end of the seventh resistor;
a first end of the ninth resistor is connected to an output end of the fifth operational amplifier, and a second end of the ninth resistor is connected to a second end of the seventh resistor.
11. The capacitive touch screen touch matrix repair circuit according to claim 1, further comprising a switch module, respectively connected to the in-phase amplification circuit, the inverting amplification circuit and the control module, for controlling on/off of connection between the in-phase amplification circuit and a positive terminal of the touch matrix circuit according to a switch instruction of the control module, and/or controlling on/off of connection between the inverting amplification circuit and a negative terminal of the touch matrix circuit according to a switch instruction of the control module.
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| CN202111072793.4A CN113868049A (en) | 2021-09-14 | 2021-09-14 | Touch matrix repair circuit of capacitive touch screen |
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Cited By (1)
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| CN115065326A (en) * | 2022-08-16 | 2022-09-16 | 基合半导体（宁波）有限公司 | Analog front-end circuit, chip and electronic equipment |
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