CN110411483A - Readout circuit and sensor array of new large-scale sensor array - Google Patents

Abstract

The invention discloses a novel readout circuit of a large-scale sensing array, which includes several parallel channels, and each parallel channel includes a differential detection module, a signal cross-coupling module and a differential integration module sequentially connected in series; the differential detection module will The charge signal output by the large-size sensor array is converted into a first voltage signal and uploaded to the signal cross-coupling module; the signal cross-coupling module converts the first voltage signal into one positive phase voltage signal and one negative phase voltage signal and uploads it to the differential integration module; The differential integration module differentially integrates the positive phase voltage signal and the negative phase voltage signal and outputs it to the subsequent peripheral signal processing circuit of the large-size sensor array. The invention also discloses a large-scale sensing array comprising the readout circuit of the novel large-scale sensing array. The invention greatly improves the strength of the readout signal, making it easier to identify the touch signal of the large-size sensing array; and the circuit is simple and reliable, and the cost is low.

Description

Readout circuit and sensor array of new large-scale sensor array

technical field

The invention specifically relates to a readout circuit of a novel large-scale sensor array and the sensor array thereof.

Background technique

Array sensor technology plays an important role in modern electronic products and equipment. In recent years, array-type electromechanical coupling, micro-electromechanical coupling, photoelectric coupling, acoustic-electric coupling and other sensors have made great progress. In particular, touch sensors, fingerprint sensors, acceleration sensors, and image sensors based on photodiodes/transistors based on thin-film capacitor arrays or microelectromechanical technology (MEMS) capacitor arrays have been widely used in consumer electronics products such as mobile phones, tablets, and smart cameras. successful application. Due to the continuous improvement of control and sensing precision, the requirements for the readout circuit of the sensing array are getting higher and higher. It is foreseeable that in the application scenarios of 5G Internet of Things and Internet of Vehicles, array sensors will be more widely used. Due to the expansion of the scale of the sensing array, the strength of the coupling between the multi-physics fields decreases, and the amount of interference and noise increases, all of which require a new readout circuit design of the sensing array. Figure 1 schematically shows the drive circuit, readout circuit and connection relationship of the array sensor. Although the specific implementation and even the sensing mechanism of sensors vary widely, they all generally adopt an array arrangement, and their driving and readout circuits are basically the same.

Take capacitive touch array technology as an example. Touch screen technology makes human-computer interaction more convenient, and is widely used in consumer electronics, industrial control equipment, and automotive electronics. Currently, capacitive touch is the most mainstream touch screen technology. Compared with resistive touch or infrared touch, capacitive touch has the advantages of supporting multi-touch, strong anti-noise capability, high technology maturity, and low manufacturing cost. At the present stage, large-size and high-resolution touch technology is an important development direction in applications such as automotive electronics, electronic whiteboards, and electronic conference systems. Fig. 2 schematically shows the drive circuit (TX), the readout circuit (RX) and their connections (TX1-TXn, Rx1-Rxm) of the capacitive sensor array. The driving line (TX) and the readout line (RX) are located in two metal layers and form a coupled array structure vertically crossed; the electrode materials of TX and RX are generally required to be both conductive and transparent, and indium tin oxide (ITO) is common choose. There are several rhombic electrodes on each line, and mutual capacitance will be generated between two adjacent rhombic electrodes. When a finger touches the screen, it will affect the electric field distribution at each intersection point (that is, mutual capacitance); since a part of the electric force line flows into the ground through the human body, this will cause the mutual capacitance to become smaller, and the amount of charge on the readout line will also become smaller. Therefore, the variation of the mutual capacitance is converted into the variation of the voltage signal and read out, and the occurrence of the touch position can be located through the coordinate axes (TX, RX).

When the size of the touch screen increases, the lengths of the TX and RX lines increase accordingly, so the parasitic resistance-capacitance (RC) values of the TX and RX lines also increase. Due to the charging/discharging loss on the driving line TX, the intensity of the output signal of the touch readout circuit will decrease. Furthermore, due to the increase in the size of the touch screen, the corresponding number of driving channels TX and readout channels RX will also increase. In order to ensure a certain refresh frequency, the detection time of each driving channel will be reduced, and at this time, the integration time of the readout channel will also be reduced, and the readout intensity of the signal will be further reduced.

The principles of the photoelectric image sensor array and the capacitive touch array are similar. FIG. 3 schematically shows the drive circuit (TX), readout circuit (RX), pixel circuit and their connection relationship (TX1-TXn, Rx1-Rxm) of the photoelectric sensor array. Here, the difference in the photoelectric leakage current of the photodiode/transistor can be used to sense the external environment and form an image. Similar to the capacitive touch array, when the image spatial resolution is improved and the array scale is larger, the readout circuit of the photoelectric image sensor array also faces problems such as reduced integration time and reduced signal readout intensity.

The traditional sensor array readout circuit design is relatively mature. The whole readout system includes drive signal generator, capacitance change readout circuit, analog-to-digital conversion circuit (ADC), data processor and other parts. The driving signal is generally a square wave or other waveforms. The readout circuit adjusts the induction signal transmitted by the readout channel through a switch MOS tube, extracts the half-period signal of the same phase for integration and reads it out with the ADC. However, this conventional readout circuit design cannot solve the problems of large amount of RC delay and low signal strength faced by large-size, high-resolution, high-refresh-rate sensor arrays.

Contents of the invention

One of the objectives of the present invention is to provide a novel readout circuit for large-scale sensing arrays that is suitable for large-scale sensing arrays and has high reliability and high sensitivity.

The second object of the present invention is to provide a large-scale sensing array including the readout circuit of the novel large-scale sensing array.

The readout circuit of this novel large-size sensor array provided by the present invention includes several parallel channels, and each parallel channel includes a differential detection module, a signal cross-coupling module and a differential integration module; a differential detection module, a signal The cross-coupling module and the differential integration module are connected in series in sequence; the input end of the differential detection module is connected to the output end of the large-scale sensing array; the differential detection module is used to convert the charge signal output by the large-scale sensing array into a first voltage signal and perform noise After elimination, it is uploaded to the signal cross-coupling module; the signal cross-coupling module is used to convert the uploaded first voltage signal into a positive phase voltage signal and a negative phase voltage signal, and upload them to the differential integration module at the same time; the differential integration module is used for The uploaded positive phase voltage signal and negative phase voltage signal are differentially integrated, and output to the subsequent peripheral signal processing circuit of the large-scale sensor array.

The differential detection module is composed of a differential operational amplifier circuit.

The differential detection module includes a differential detection first input capacitance, a differential detection second input capacitance, a differential detection first input resistance, a differential detection second input resistance, a differential detection first filter capacitor, a differential detection second filter capacitor and a differential Detection amplifier; two signals output by the large-size sensor array, one of which is input to the input terminal of the differential detection operational amplifier through the first input capacitor of the differential detection in series, and the other is input to the differential detection through the second input capacitor of the differential detection in series The other end of the input end of the operational amplifier, the first input resistor of the differential detection is connected between one end of the input end of the differential detection amplifier and the output end of the differential detection amplifier, and the second input resistor of the differential detection is connected between the other end of the input end of the differential detection amplifier and the other end of the input end of the differential detection amplifier. Between the ground; the first filter capacitor for differential detection is connected in parallel at both ends of the first input resistor for differential detection, and the second filter capacitor for differential detection is connected in parallel at both ends of the second input resistor for differential detection; the output terminal of the differential detection amplifier is the differential detection output of the module.

The differential integration module is a differential integration circuit composed of operational amplifiers.

The differential integration module includes a differential integration first resistor, a differential integration second resistor, a differential integration first capacitor, a differential integration second capacitor and a differential integration operational amplifier; the input negative pole of the differential integration operational amplifier is connected in series with the differential integration first input resistor ; The input positive pole of the differential integral operational amplifier is connected in series with the second input resistor of differential integral; the negative pole of the differential integral operational amplifier is connected in series with the output terminal of the differential integral operational amplifier; the first capacitance of differential integral is connected in series; The second capacitor for differential integration is connected in series; the negative phase voltage signal output by the signal cross-coupling module is connected to the first resistor for differential integration, and the positive phase voltage signal output by the signal cross-coupling module is connected to the second resistor for differential integration.

The signal cross coupling module includes a signal cross first rectifier circuit, a signal cross second rectifier circuit and a signal cross reverse circuit; the first voltage signal output by the differential detection module is converted into a negative phase after being rectified by the signal cross first rectifier circuit The voltage signal is output to the differential integration module; the first voltage signal output by the differential detection module is also reversed by the signal crossing reverse circuit, and then rectified by the signal crossing second rectification circuit and converted into a positive phase voltage signal, and output to the differential integrator circuit.

The signal crossing first rectification circuit is a passive rectification circuit composed of diodes.

The signal crossing second rectification circuit is a passive rectification circuit composed of diodes.

The signal crossing first rectification circuit is an active rectification circuit composed of switching tubes.

The signal crossing second rectification circuit is an active rectification circuit composed of switching tubes.

The invention also discloses a large-scale sensing array, which includes the readout circuit of the novel large-scale sensing array.

The readout circuit of the novel large-size sensor array and its large-size sensor array provided by the present invention cross-couple the signals output by the large-size sensor array and The differential output greatly improves the strength of the readout signal, thereby making it easier to identify the touch signal of the large-size sensor array; moreover, the circuit of the present invention is simple, reliable, and low in cost.

Description of drawings

FIG. 1 is a schematic diagram of a sensor array driving circuit, a readout circuit and their connections.

FIG. 2 is a schematic diagram of a drive circuit (TX), a readout circuit (RX) and their connections (TX1˜TXn, Rx1˜Rxm) of the capacitive sensor array.

3 is a schematic diagram of a drive circuit (TX), a readout circuit (RX), a pixel circuit and their connections (TX1-TXn, Rx1-Rxm) of the photoelectric sensor array.

FIG. 4 is a schematic configuration diagram of adjacent two column readout circuits (RX[n] and RX[n+1]) of a conventional sensor array.

FIG. 5 is a schematic diagram of the composition of adjacent column readout circuits of the sensor array in the existing correlative sampling technology.

FIG. 6 is a schematic diagram of the composition of adjacent column readout circuits of the sensor array in the existing correlative sampling technology.

FIG. 7 is a schematic diagram of the composition of a column readout circuit of a sensor array with correlated sampling quadruple integration of the present application.

FIG. 8 is a schematic diagram of a coupling link implemented based on capacitance in a column readout circuit of a sensor array with correlated sampling quadruple integration in the present application.

FIG. 9 is a schematic diagram of a coupling link implemented based on dual CMOS cross-coupled switches in the column readout circuit of the correlated sampling quadruple integration sensor array of the present application.

FIG. 10 is a schematic diagram of a first embodiment of a cross-coupling link in a column readout circuit of a sensor array with correlated sampling quadruple integration of the present application.

FIG. 11 is a schematic diagram of the timing principle of the first embodiment of the cross-coupling link in the column readout circuit of the correlated sampling quadruple integration sensor array of the present application.

FIG. 12 is a schematic diagram of a second embodiment of the cross-coupling link in the column readout circuit of the correlated sampling quadruple integration sensor array of the present application.

FIG. 13 is a schematic diagram of the timing principle of the second embodiment of the cross-coupling link in the column readout circuit of the correlated sampling quadruple integration sensor array of the present application.

FIG. 14 is a schematic diagram of a third embodiment of a column readout circuit of a correlated sampling quadruple integration sensor array of the present application.

FIG. 15 is a schematic diagram of the timing principle of the third embodiment of the column readout circuit of the correlated sampling quadruple integration sensor array of the present application.

FIG. 16 is a schematic diagram of the simulation results of the readout circuit of the present application.

FIG. 17 is a schematic diagram of the experimental results of the readout circuit of the present application.

Detailed ways

4 is a schematic diagram of the structure of two adjacent readout circuits (RX[n] and RX[n+1]) of the existing sensor array, wherein the single-row readout circuit includes an amplification circuit (k times), an integrating circuit, ADC circuit; the output signal (TX) of the driving circuit is attenuated due to the parasitic resistance-capacitance (RC) on the line; the noise in the array disturbs the signals of RX[n] and RX[n+1]. Wherein, the readout circuit of each column includes an amplifier circuit, an integration circuit, an ADC circuit, and the like. The amplification circuit can amplify the column read signal by k times; the function of the integration circuit is to suppress the amount of noise and enhance the effective signal through the superposition of signals in the time domain; the function of the ADC circuit is to digitize the output analog quantity to facilitate subsequent circuits and systems further processing. The readout circuit of this classic sensor array shown in Figure 4 is widely used in occasions where the array is small in scale, the resolution is not high, and the refresh rate is low. However, after the scale of the sensing array increases, the parasitic resistance-capacitance (RC) effect on the output signal (TX) line of the driving circuit will increase significantly. As shown in FIG. 4 , when the value of RC increases, the signal on the driving line TX attenuates, and the driving waveform is severely distorted. For large-scale sensing arrays, such as large-scale capacitive touch screens, it is easy to cause sensors at different positions (near and far ends in the TX direction of the drive line; near and far ends in the RX direction of the readout line) The output varies greatly. In particular, there are more noise sources in the large-scale sensor array, for example, in a large-scale photoelectric sensor array, with the increase of pixel units on the RX[n] and RX[n+1] lines, the leakage current of the switching device in the pixel The amount of noise caused is significantly higher, and these noise currents may be comparable to photocurrents. To sum up, improving the sensing signal strength, reducing the non-uniformity of the readout signal, and reducing the noise signal of the readout channel are the key issues in the design of high-performance sensing arrays.

FIG. 5 schematically illustrates the adjacent column readout circuits of the sensor array of the existing correlation sampling technology, wherein two adjacent columns of readout pixels share an amplification circuit (k times), an integrating circuit, and an ADC circuit. The starting point here is that the readout channels of the adjacent two columns of the sensing array sense equal noise signals, and this assumption is basically true for the noise and interference signals caused by the preparation of the sensing array and the driving method. The adjacent two columns of readout pixels share the amplifier circuit (k times), the integration circuit and the ADC circuit, and detect the difference between the physical quantities of the sensor array by making a difference between the sensor signals of the two adjacent columns, such as a capacitive touch array In , the capacitance difference of the pixel parts corresponding to the adjacent two columns in the same row. This sensor array readout architecture can better solve the problem of readout noise, but it has no effect on the problem of readout signal uniformity and weak readout signal strength caused by RC delay.

Fig. 6 schematically shows the structure of the adjacent column readout circuit of the sensor array for the existing correlation sampling technology, the influence of RC delay is reduced by increasing the coupling link; the integration intensity is increased by the feedback loop of the inverter. This architecture adds a coupling link between the sensing array and the readout circuit, while adding an inverter feedback loop in front of the integrator. Through the synergistic effect of the coupling link and the non-overlapping clock signals of CK and XCK, the sensor output corresponding to the rising edge and falling edge of the TX signal is sampled, and the signal integration is completed respectively. This sensor array readout architecture has a certain effect on suppressing the amount of readout noise and improving the readout signal strength. However, the problem of readout signal uniformity caused by RC delay and how to further improve the readout signal strength require new methods. circuit design.

Fig. 7 illustrates the structure of the column readout circuit of the sensor array of the correlative sampling quadruple integration of the present application, and the new cross-coupling link responds to the rising edge and the falling edge of the TX signal respectively, so that the rising edge and the falling edge of the TX signal realize respectively 2-fold integration, a total of four-fold integration output of the sensor array signal. The structure has a cross-coupling link. Through the timing coordination of the coupling link and the cross-coupling link, the sensor output corresponding to the rising edge of the TX signal is integrated to achieve 2-fold integration, and the sensor output corresponding to the falling edge of the TX signal is also realized. 2-fold integration, so that a total of 4-fold integration output of the sensor array signal is realized.

FIG. 8 is a specific embodiment of the coupling link implemented based on capacitance in the column readout circuit of the correlated sampling quadruple integration sensor array of the present application. The advantage of using capacitive coupling is not only the simple structure, but also the fast speed of capacitive coupling, which can suppress the problem of uneven readout signal caused by RC delay to a certain extent. A possible disadvantage of capacitive coupling is the overall reduction in signal amplitude; however, for the overall reduction in signal amplitude, the uniformity across the sensing array is high.

FIG. 9 is a specific embodiment of the coupling link implemented based on double CMOS cross-coupled switches in the column readout circuit of the correlated sampling quadruple integration sensor array of the present application. The CMOS cross-coupling switch can cooperate with the TX signal to increase the output value of the sensing array readout circuit by inverting the polarity of the input signal of the sensing array readout circuit.

The following will take the large-size capacitive touch array as an example to explain the specific implementation methods of other links of the readout circuit.

FIG. 10 schematically illustrates a first embodiment of a column readout circuit of a correlated sampling quadruple integration sensor array of the present application. The readout circuit of this novel large-size sensor array provided by the present invention includes several parallel channels, and each parallel channel includes a differential detection module, a signal cross-coupling module and a differential integration module; a differential detection module, a signal The cross-coupling module and the differential integration module are connected in series in sequence; the input end of the differential detection module is connected to the output end of the large-scale sensing array; the differential detection module is used to convert the charge signal output by the large-scale sensing array into a first voltage signal and perform noise After elimination, it is uploaded to the signal cross-coupling module; the signal cross-coupling module is used to convert the uploaded first voltage signal into a positive phase voltage signal and a negative phase voltage signal, and upload them to the differential integration module at the same time; the differential integration module is used for The uploaded positive phase voltage signal and negative phase voltage signal are differentially integrated, and output to the subsequent peripheral signal processing circuit of the large-scale sensor array.

In specific implementation, the differential detection module may be composed of a differential operation amplifier circuit; the differential integration module is a differential integration circuit composed of an operational amplifier.

Figure 10 is a schematic diagram of the circuit principle of the first embodiment of the readout circuit, which is based on a clock-controlled MOS switch: In this embodiment, the circuit in the figure includes four parts, which are the leftmost touch screen equivalent circuit, differential detection module circuit, signal cross-coupling module circuit and differential integration module circuit.

The equivalent circuit of the touch screen is used to simulate the signals output by the two readout channels after there is a touch on the screen, namely Vin1 and Vin2.

The differential detection module includes a differential detection first input capacitor C1, a differential detection second input capacitor C2, a differential detection first input resistor R1, a differential detection second input resistor R2, a differential detection first filter capacitor C3, and a differential detection second filter capacitor C4 and differential detection amplifier OP1; the two-way signal output by the large-scale sensor array, one way (Vin1) is input to the input end of the differential detection operational amplifier through the first input capacitor of the series differential detection, and the other way (Vin2) is passed through the series connection The second input capacitor for differential detection is input to the other end of the input end of the differential detection operational amplifier, the first input resistor for differential detection is connected between one end of the input end of the differential detection amplifier and the output end of the differential detection amplifier, and the second input resistor for differential detection is connected to Between the other end of the input terminal of the differential detection amplifier and the ground; the first filter capacitor for differential detection is connected in parallel to both ends of the first input resistor for differential detection, and the second filter capacitor for differential detection is connected in parallel to both ends of the second input resistor for differential detection; The output terminal of the differential detection amplifier is the output terminal of the differential detection module.

The differential integration module includes a differential integration first resistor R5, a differential integration second resistor R6, a differential integration first capacitor C5, a differential integration second capacitor C6, and a differential integration operational amplifier OP3; the input negative pole of the differential integration operational amplifier is connected in series with the differential integration first Input resistance; the input positive pole of the differential integral operational amplifier is connected in series with the second input resistor of differential integral; the first capacitor of differential integral is connected in series between the input negative pole of the differential integral operational amplifier and the output terminal of the differential integral operational amplifier; the input positive pole of the differential integral operational amplifier The second capacitor for differential integration is connected in series with the ground; the negative phase voltage signal output by the signal cross-coupling module is connected to the first resistor for differential integration, and the positive phase voltage signal output by the signal cross-coupling module is connected to the second resistor for differential integration.

The signal cross-coupling module includes a signal crossing first rectification circuit (in the figure including switch tubes T1 and T2), a signal crossing second rectifying circuit (in the figure including switching tubes T3 and T4) and a signal crossing reverse circuit (in the figure including operating Put OP2, and resistors R3 and R4); the first voltage signal output by the differential detection module is converted into a negative phase voltage signal (the voltage signal at point D in the figure) after being rectified by the signal crossing first rectification circuit, and output to the differential integration module ; The first voltage signal output by the differential detection module is also reversed through the signal crossing reverse circuit (the reverse can be enlarged or reduced at the same time, and the resistance values of R3 and R4 can be adjusted specifically), and then through the signal crossing second rectification After the circuit is rectified, it is converted into a positive phase voltage signal (the voltage signal at point C in the figure), and is output to the differential integration circuit; and It is the driving signal of the switch tube.

In this embodiment, both the signal crossing first rectification circuit and the signal crossing second rectification circuit use active rectification circuits composed of transistors.

As shown in Figure 11, it is a schematic diagram of the circuit timing principle of the first embodiment of the readout circuit of the present invention: when a touch action occurs on the sensing panel, the mutual capacitance cm1 and cm2 are not equal in size, and at this time the two detection signals The amplitudes of Vin1 and Vin2 are not equal, they are subtracted by the operational amplifier OP1 and then amplified, and a touch signal is obtained at node A (as shown by A in Figure 10). The touch signal is divided into two paths. After the other path passes through the inverting amplifier circuit composed of op amp OP2, an inverting signal is obtained at node B, and the resistor R3 and resistor R4 are set to be equal in size, so the amplitude of the inverting signal is also equal ( As shown in B in Figure 11). In one cycle, when for high level, When it is low level, the positive peak signal of node A is input to node D through switch tube T2, and the negative peak signal of node B is input to node C through switch tube T3; when is low, When it is at a high level, the negative spike signal at node A is input to node C through switch T1, and the positive spike signal at node B is input to node D through switch T4. Therefore, in one cycle, node C has two negative-going spikes input to the integrator, and node D has two positive-going spikes input to the integrator. After the touch signal is processed by the signal cross-coupling module, the number of positive peak signals and negative peak signals is doubled in the same time period, and the integral output value is increased to four times the original value after differential integration. In the same time period, by increasing the integrated signal amount to increase the integrated output value, the problem of the charge reduction of the large-scale sensor array after the RC delay is increased is effectively solved, and the sensitivity is high, which is suitable for the large-scale sensor array.

Figure 12 is a schematic diagram of the circuit principle of the second embodiment of the readout circuit of the present invention, which is based on multi-diode control: the figure also includes the leftmost touch screen equivalent circuit, differential detection module circuit, signal cross-coupling Module circuit and differential integration module circuit. Moreover, the equivalent circuit of the touch screen, the differential detection module circuit and the differential integration module circuit are all the same as the circuit in FIG. 10 .

The signal cross coupling module includes a signal cross first rectification circuit (includes diodes D1 and D2 in the figure), a signal cross second rectifier circuit (includes diodes D3 and D4 in the figure) and a signal cross reverse circuit (includes operational amplifier OP2 in the figure) , and resistors R3 and R4); the first voltage signal output by the differential detection module is converted into a negative phase voltage signal (the voltage signal at point D in the figure) after being rectified by the signal crossing first rectification circuit, and output to the differential integration module; The first voltage signal output by the detection module is also reversed through the signal crossing reverse circuit (the reverse can be enlarged or reduced at the same time, and the resistance values of R3 and R4 can be adjusted specifically), and then rectified by the signal crossing second rectification circuit After that, it is converted into a positive phase voltage signal (the voltage signal at point C in the figure), and is output to the differential integration circuit; and It is the driving signal of the switch tube.

In this embodiment, both the signal crossing first rectification circuit and the signal crossing second rectification circuit adopt passive rectification circuits composed of diodes.

As shown in Figure 13, it is a schematic diagram of the circuit timing principle of the second embodiment of the readout circuit of the present invention: when a trigger event occurs on the sensor array, the mutual capacitance cm1 and cm2 are not equal in size, and the two detection signals The amplitudes of Vin1 and Vin2 are not equal, they are subtracted by the operational amplifier OP1 and then amplified, and a touch signal is obtained at node A (as shown by A in Figure 12). The touch signal is divided into two paths. After the other path passes through the inverting amplifier circuit composed of op amp OP2, an inverting signal is obtained at node B, and the resistor R3 and resistor R4 are set to be equal in size, so the amplitude of the inverting signal is also equal ( As shown in B in Figure 12). In one cycle, the positive peak signal of node A is input to node C through diode D1, the negative peak signal of node B is input to node D through diode D4; the negative peak signal of node A is input to node D through diode D2, The forward peak signal at node B is input to node C through diode D3. Therefore, in one cycle, node C has two negative spikes input to the integrator, and node D has two positive spikes input to the integrator. After the touch signal is processed by the signal cross-coupling module, the number of positive peak signals and negative peak signals is doubled in the same time period, and the integral output value is increased to four times the original value after differential integration. In the same time, by increasing the integral signal amount to increase the integral output value, it effectively solves the problem that the charge amount of the large-scale sensor array decreases after the RC delay increases. The sensitivity is high, and it is suitable for large-scale high-resolution sensors. sensing array.

As shown in Figure 14, it is a schematic diagram of the circuit principle of the third embodiment of the readout circuit of the present invention: different from the first embodiment of Figure 10, the driving signal of the embodiment in this figure (the driving signal of the sensing array ) is a sine wave.

As shown in Figure 15, it is a schematic diagram of the circuit timing principle of the third embodiment of the readout circuit of the present invention: when there is a trigger behavior on the sensor array, the mutual capacitance cm1 and cm2 are not equal in size, and at this time the two detection signals Vin1 It is not equal to the amplitude of Vin2, it is subtracted by the operational amplifier OP1 and then amplified, and a touch signal is obtained at node A (as shown by A in Figure 14). The touch signal is divided into two paths. After the other path passes through the inverting amplifier circuit composed of op amp OP2, an inverting signal is obtained at node B, and the resistor R3 and resistor R4 are set to be equal in size, so the amplitude of the inverting signal is also equal ( As shown in B in Figure 14). In one cycle, when for high level, When it is low level, the positive peak signal of node A is input to node D through switch tube T2, and the negative peak signal of node B is input to node C through switch tube T3; when is low, When it is at a high level, the negative spike signal at node A is input to node C through switch T1, and the positive spike signal at node B is input to node D through switch T4. Therefore, in one cycle, node C has two negative-going spikes input to the integrator, and node D has two positive-going spikes input to the integrator. After the touch signal is processed by the signal cross-coupling module, the number of positive peak signals and negative peak signals is doubled in the same time period, and the integral output value is increased to four times the original value after differential integration.

The advantage of the third embodiment of the present invention is:

1) Through the cross-coupling module, the integral output value of the readout circuit is effectively increased within the same time period, so that the sensitivity of the large-scale sensing array is higher and the output intensity is greater.

2) Through the sinusoidal signal driving method, through the cooperation of the cross-coupling module, the problem of uneven readout signal intensity caused by RC delay on the large-scale sensing array is suppressed. The impact caused by the RC delay on the TX and RX lines can be equivalent to low-pass filtering. Since the TX square wave signal contains rich spectrum information, it is easy to cause differences in sensing signals in different corners of the sensing array. In the sinusoidal signal driving method, the frequency spectrum received by the RX can be relatively pure, which is beneficial to reduce the non-uniformity of the sensing array.

3) In the readout structure of the traditional sensor array, as shown in Figure 6, due to the sinusoidal signal and non-overlapping sampling clock and The timing alignment problem is easy to introduce waveform distortion of the readout signal. The cross-coupling module of this embodiment, no matter for The sampling phase of the , or In the sampling stage, the input signal and its inverted signal are synchronously input to the positive and negative input terminals of the integrator. Therefore, through the canceling effect of the positive and negative input terminals of the integrator, the distortion problem of the readout signal of the sensing array can be overcome, which is beneficial to reduce the non-uniformity of the sensing array.

As shown in Figure 16, it is a schematic diagram of the simulation results of the readout circuit of the present invention: it can be seen that, within the same time period, the circuit proposed by the present invention integrates twice more than the traditional circuit, and the integral value is increased by 4 times at the same time, effectively It solves the problem that the charge amount of the large-scale sensor array decreases after the RC delay increases, and has high sensitivity, which is suitable for large-scale high-resolution sensor arrays.

As shown in Figure 17, it is a schematic diagram of the experimental results of the readout circuit of the present invention: it can be seen that the circuit proposed by the present invention has an integral output in each half cycle, which is 2 times more integrated than the traditional circuit, which is consistent with the simulation results . This circuit effectively solves the problem of the charge reduction of the large-scale sensor array after the RC delay increases, and has high sensitivity, which is suitable for large-scale high-resolution sensor arrays.

Claims (9)

1. A readout circuit of a novel large-scale sensing array, characterized in that it comprises several parallel channels, each of which includes a differential detection module, a signal cross-coupling module and a differential integration module; a differential detection module, The signal cross-coupling module and the differential integration module are connected in series in sequence; the input end of the differential detection module is connected to the output end of the large-scale sensing array; the differential detection module is used to convert the charge signal output by the large-scale sensing array into a first voltage signal and perform The noise is eliminated and then uploaded to the signal cross-coupling module; the signal cross-coupling module is used to convert the uploaded first voltage signal into a positive phase voltage signal and a negative phase voltage signal, and upload them to the differential integration module at the same time; the differential integration module is used It is used to differentially integrate the uploaded positive phase voltage signal and negative phase voltage signal, and output it to the subsequent peripheral signal processing circuit of the large-size sensor array. 2. The readout circuit of the novel large-scale sensor array according to claim 1, characterized in that the differential detection module is composed of a differential operational amplifier circuit. 3. The readout circuit of the novel large-size sensor array according to claim 2, wherein the differential detection module includes a differential detection first input capacitance, a differential detection second input capacitance, a differential detection first input resistance , the second input resistance for differential detection, the first filter capacitor for differential detection, the second filter capacitor for differential detection, and the differential detection amplifier; the two signals output by the large-scale sensor array are input to the differential through the first input capacitor for differential detection in series. One end of the input end of the detection operational amplifier is input to the other end of the input end of the differential detection operational amplifier through the second input capacitor of the differential detection in series, and the first input resistance of the differential detection is connected to one end of the input end of the differential detection amplifier and the differential detection amplifier Between the output terminals of the differential detection, the second input resistor of the differential detection is connected between the other input terminal of the differential detection amplifier and the ground; the first filter capacitor of the differential detection is connected in parallel at both ends of the first input resistance of the differential detection, and the second filter The capacitor is connected in parallel to the two ends of the second input resistor for differential detection; the output end of the differential detection amplifier is the output end of the differential detection module. 4. The readout circuit of the novel large-scale sensor array according to claim 1, characterized in that said differential integration module is a differential integration circuit composed of operational amplifiers. 5. The readout circuit of the novel large-scale sensor array according to claim 4, characterized in that the differential integration module includes a differential integration first resistor, a differential integration second resistor, a differential integration first capacitor, a differential integration The second capacitor and the differential integration operational amplifier; the input negative pole of the differential integration operational amplifier is connected in series with the first input resistance of differential integration; the input positive pole of the differential integration operational amplifier is connected in series with the second input resistor of differential integration; the input negative pole of the differential integration operational amplifier is connected with the differential integration operation The first capacitor for differential integration is connected in series between the output terminals of the amplifier; the second capacitor for differential integration is connected in series between the input positive pole of the differential integration operational amplifier and the ground; the negative phase voltage signal output by the signal cross-coupling module is connected to the first resistor for differential integration, The positive phase voltage signal output by the signal cross-coupling module is connected to the second resistor for differential integration. 6. The readout circuit of a novel large-scale sensor array according to any one of claims 1 to 5, characterized in that the signal cross-coupling module includes a signal crossing first rectification circuit, a signal crossing second rectification circuit and a signal crossing Cross reverse circuit; the first voltage signal output by the differential detection module is converted into a negative phase voltage signal after being rectified by the signal cross first rectifier circuit, and output to the differential integration module; the first voltage signal output by the differential detection module is also passed through the signal cross After the inversion circuit reverses, it is rectified by the signal crossing second rectification circuit and converted into a positive phase voltage signal, and output to the differential integration circuit. 7. The readout circuit of the novel large-scale sensing array according to claim 6, characterized in that the first rectification circuit for crossing the signal is a passive rectification circuit made of diodes; the second rectifying circuit for crossing the signal is The circuit is a passive rectification circuit composed of diodes. 8. The readout circuit of the novel large-scale sensor array according to claim 6, characterized in that the first rectification circuit of the signal crossing is an active rectification circuit composed of switching tubes; the second crossing of the signal is The rectification circuit is an active rectification circuit composed of switching tubes. 9. A large-scale sensing array, characterized in that it comprises a readout circuit of the novel large-scale sensing array according to any one of claims 1-8.