Front-end circuit, front-end identification circuit and display device suitable for touch panel

Abstract

The present disclosure provides a front-end circuit, a front-end identification circuit and a display device suitable for a touch panel, the front-end circuit comprising: a transmitting channel module configured to output detection signals with different frequencies to respective channels of the touch panel; a differential charge amplification module configured to perform differential processing and amplification processing on channel signals of two adjacent receiving channels of the touch panel to obtain a differential signal; a receiving channel determination module configured to determine a receiving position of a touch point in a receiving channel according to the differential signal and a preset differential threshold; a transmitting channel determination module configured to determine a transmitting position of the touch point according to the detection signal, a corresponding quadrature signal of the detection signal and a voltage signal corresponding to the differential signal; and a touch area acquisition module configured to acquire channel signals within a preset range of the touch point to determine a touch area where the touch point is located. The embodiment can reduce the amount of channel signals to be acquired, which is conducive to reducing the data processing amount and improving the processing efficiency.

Description

Technical Field

[0001] This disclosure relates to the field of touch control, and more particularly to a front-end circuit, a front-end recognition circuit, and a display device suitable for touch panels. Background Technology

[0002] Display devices are widely used in various scenarios. For example, in a meeting setting, users can write on a touch-screen display, making it easier for attendees to understand the content.

[0003] As display devices become larger, the number of touch panels on these devices needs to be processed, leading to an increase in the number of touch panel samples and processes.

[0004] However, for large-sized display devices, the touch area occupies only a small portion of the display area, and most of the area is not touched. This means that most of the data detected by each touch is invalid, and the touch panel processes a lot of invalid data. Furthermore, as the size of the display device increases, the proportion of invalid data also increases, resulting in a waste of computing resources.

[0005] In addition, larger display devices receive smaller touch signals, which increases the likelihood of interference. In other words, weak touch signals are often drowned out by loud noise, reducing the accuracy of touch signal detection. Summary of the Invention

[0006] This disclosure provides a front-end circuit, a front-end recognition circuit, and a display device suitable for touch panels to solve the above-mentioned technical problems.

[0007] According to a first aspect of this disclosure, a front-end circuit suitable for a touch panel is provided, the front-end circuit comprising: a differential charge amplification module, a receiving channel determination module, a transmitting channel determination module, a transmitting channel module, and a touch area acquisition module; the differential charge amplification module is electrically connected to the touch panel and the receiving channel determination module respectively; the transmitting channel determination module is electrically connected to the receiving channel determination module and the touch area acquisition module respectively; the transmitting channel module is electrically connected to the transmitting channel determination module, the touch area acquisition module, and the touch panel respectively.

[0008] The transmission channel module is used to output detection signals of different frequencies to each channel of the touch panel respectively;

[0009] The differential charge amplification module is used to perform differential processing and amplification on the channel signals of two adjacent receiving channels in the touch panel to obtain a differential signal;

[0010] The receiving channel determination module is used to determine the receiving position of the contact in the receiving channel based on the differential signal and a preset differential threshold.

[0011] The transmission channel determination module is used to determine the transmission position of the contact point based on the detection signal, the orthogonal signal corresponding to the detection signal, and the voltage signal corresponding to the differential signal.

[0012] The touch area acquisition module is used to acquire channel signals within a preset range of the touch point in order to determine the touch area where the touch point is located.

[0013] Optionally, the differential charge amplification module includes a charge amplification unit, a differential amplification unit, and a programmable gain amplification unit;

[0014] The charge amplification unit is used to perform differential processing on the channel signals of two adjacent receiving channels in the touch panel to obtain a differential initial signal;

[0015] The differential amplification unit is used to amplify the differential initial signal to obtain a differential amplified signal;

[0016] The programmable gain amplification unit is used to amplify the differential amplified signal to obtain the differential initial signal.

[0017] Optionally, the charge amplification unit includes a first amplifier, a first resistor, and a first capacitor;

[0018] The non-inverting input of the first amplifier receives a common-mode level, the inverting input of the first amplifier is electrically connected to the first end of the first resistor and the first end of the first capacitor respectively and receives a channel signal, and the output of the first amplifier is electrically connected to the second end of the first resistor and the second end of the first capacitor respectively and outputs a differential initial signal.

[0019] Optionally, the differential amplifier unit includes a second amplifier, a third amplifier, a fourth amplifier, a resistor array, a second resistor, and a third resistor;

[0020] The non-inverting input of the second amplifier receives the channel signal of the current stage, the inverting input of the second amplifier is electrically connected to the resistor array, and the output of the second amplifier is electrically connected to the resistor array.

[0021] The non-inverting input of the third amplifier receives the channel signal from the next stage, the inverting input of the third amplifier is electrically connected to the resistor array, and the output of the third amplifier is electrically connected to the resistor array.

[0022] The inverting input terminal of the fourth amplifier is electrically connected to the resistor array and the first terminal of the second resistor, respectively. The non-inverting input terminal of the fourth amplifier is electrically connected to the resistor array and the first terminal of the third resistor, respectively. The output terminal of the fourth amplifier is electrically connected to the second terminal of the second resistor and outputs a differential amplified signal. The second terminal of the third resistor receives the common-mode level.

[0023] Optionally, the programmable gain amplification unit includes a fifth amplifier, a fifth resistor, and an adjustable resistor;

[0024] The non-inverting input of the fifth amplifier receives the differential amplified signal, the inverting input of the fifth amplifier is electrically connected to the second terminal of the fifth resistor and the first terminal of the adjustable resistor, and the output of the fifth amplifier is electrically connected to the second terminal of the adjustable resistor and outputs the differential initial signal.

[0025] Optionally, the adjustable resistor includes a sliding resistor; or,

[0026] The adjustable resistor includes multiple resistors and a switching switch corresponding to each resistor. The multiple resistors are connected in series and then in parallel between the inverting input and output of the fifth amplifier. The switching switch corresponding to each resistor is connected in parallel across the two ends of the resistor. The control terminal of each switching switch closes to short-circuit the corresponding resistor after receiving a switching control signal.

[0027] Optionally, the receiving channel determination module includes a voltage-to-current conversion unit, a first multiplier unit, a first integrator unit, and a receiving channel determination unit;

[0028] The voltage-to-current conversion unit is used to convert the differential initial signal into a differential current signal;

[0029] The first multiplier unit is used to process the differential current signal to obtain an intermediate current signal;

[0030] The first integrator unit is used to integrate the intermediate current signal to obtain an integrated voltage;

[0031] The receiving channel determination unit is used to compare the integrated voltage and the preset differential threshold to obtain the receiving position of the contact in the receiving channel.

[0032] Optionally, the transmission channel determination module includes a second multiplier unit, a second integrator unit, and a transmission channel determination unit;

[0033] The second multiplier unit is used to multiply the differential current signal output by the receiving channel determination module according to the channel signal of the current stage and the channel signal of the next stage to obtain the current amplified signal;

[0034] The second integrator unit is used to integrate the current amplified signal to obtain the integrated voltage;

[0035] The transmission channel determination unit is used to determine the transmission channel where the contact is located based on the first preset transmission threshold, the second preset transmission threshold and the integrated voltage, and thus obtain the transmission position.

[0036] Optionally, the preset range is positively correlated with the area of ​​the touch area.

[0037] According to a second aspect of this disclosure, a front-end identification circuit is provided, comprising a front-end circuit and a processor as described in any of the first aspects; the front-end circuit and the processor are electrically connected.

[0038] The processor is used to determine a preset range of the contact point based on the transmission and reception positions of the contact point, and send the preset range to the front-end circuit;

[0039] The front-end circuit is used to acquire channel signals within a preset range of the contact point;

[0040] The processor is also used to determine the positions of other touch points based on the channel signals within a preset range of the touch points, thereby obtaining a touch area composed of all the touch points.

[0041] According to a third aspect of this disclosure, a display device is provided, including a front-end recognition circuit and a touch panel as described in the second aspect; the front-end recognition circuit is electrically connected to the touch panel.

[0042] According to a fourth aspect of this disclosure, a method for locating a touch area is provided, comprising:

[0043] Obtain the transmit and receive positions of the contact points;

[0044] The preset range of the contact point is determined based on the transmitting position and the receiving position;

[0045] Acquire channel signals within a preset range of the contact point;

[0046] The positions of other touch points are determined based on the channel signals within a preset range, thus obtaining the touch area.

[0047] The technical solutions provided by the embodiments of this disclosure may include the following beneficial effects:

[0048] The front-end circuit of this embodiment can amplify the received channel signal by setting a differential charge amplification module, thereby avoiding the influence of common-mode signal and noise signal on the channel signal and improving the accuracy of the acquired signal. In addition, after determining the contact position, this embodiment can acquire the channel signal within a preset range of the contact, which can reduce the amount of channel signal acquired, which is beneficial to reduce the amount of data processing and improve processing efficiency.

[0049] It should be understood that the above general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0050] Figure 1 This is a block diagram of a display device according to an embodiment of the present disclosure.

[0051] Figure 2 This is a block diagram of a front-end circuit according to an embodiment of the present disclosure.

[0052] Figure 3 This is a block diagram of a differential charge amplification module according to an embodiment of the present disclosure.

[0053] Figure 4 This is a circuit diagram of a charge amplification unit according to an embodiment of the present disclosure.

[0054] Figure 5 This is a circuit diagram of a differential amplifier unit according to an embodiment of the present disclosure.

[0055] Figure 6 This is a circuit diagram of a programmable gain amplifier unit according to an embodiment of the present disclosure.

[0056] Figure 7 This is a circuit diagram of another programmable gain amplifier unit according to an embodiment of the present disclosure.

[0057] Figure 8 This is a circuit diagram of another programmable gain amplifier unit according to an embodiment of the present disclosure.

[0058] Figure 9 This is a block diagram of a receiving channel determination module according to an embodiment of the present disclosure.

[0059] Figure 10 This is a circuit diagram of a voltage-to-current conversion unit according to an embodiment of the present disclosure.

[0060] Figure 11 This is a block diagram of a transmission channel determination module according to an embodiment of the present disclosure.

[0061] Figure 12 This is a block diagram of a second multiplier unit according to an embodiment of the present disclosure.

[0062] Figure 13 This is a timing diagram of a front-end circuit according to an embodiment of the present disclosure.

[0063] Figure 14 This is a schematic diagram showing the comparison of the complexity of a front-end recognition circuit before and after an update, according to an embodiment of this disclosure.

[0064] Figure 15 This is a flowchart of a touch area positioning method according to an embodiment of the present disclosure. Detailed Implementation

[0065] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numerals in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this disclosure. Rather, they are merely examples of apparatuses consistent with some aspects of this disclosure as detailed in the appended claims.

[0066] This disclosure provides a display device, which may include, but is not limited to, devices with display functions such as mobile phones, computers, tablets, e-readers, watches, 3D displays, all-in-one conference machines, and electronic whiteboards. In one example, the display device is a large-sized electronic whiteboard, a vertical screen, etc.

[0067] See Figure 1 The display device includes a touch panel and a front-end recognition circuit. The touch panel includes detection lines evenly arranged in row and column directions. In one example, the detection lines in the row direction can be called receive lines or receive channels (RX); the detection lines in the column direction can be called transmit lines or transmit channels (TX).

[0068] Understandably, the overlapping area between the receiving and transmitting lines forms a capacitor, which can be called the mutual inductance capacitance Cm. When a transmitting signal is input to the transmitting channel, a detection signal (hereinafter referred to as the channel signal) can be received at the electrodes of the receiving channel. This detection signal is the touch signal that needs to be processed and recognized. When a finger or other detectable object approaches (touches or is within a preset distance threshold) the touch panel, the capacitance value of the mutual inductance capacitance Cm changes. Based on the change in capacitance value, the position of the touch point (in the row direction) can be determined. Combined with the position of the transmitting channel (in the column direction), the position of the touch point in both the row and column directions can be determined.

[0069] Understandably, when the touch panel is small, there are fewer row and column detection lines and fewer mutual inductors on the touch panel. This results in fewer digital processors and lower computational resource requirements for the display device. However, as the touch panel size increases, such as to 50-100 inches or even larger, the number of mutual inductors also increases, leading to a larger data processing volume and higher computational resource requirements.

[0070] To address the aforementioned technical problems, subsequent embodiments of this disclosure improve the front-end recognition circuit. In one example, the front-end recognition circuit includes a front-end circuit and a processor, which are electrically connected. Specifically, subsequent embodiments improve the aforementioned front-end circuit, which will not be described here. The processor of the front-end device circuit is used to determine a preset range of the touch point based on the transmitting and receiving positions of the touch point, and sends the preset range to the front-end circuit; the front-end circuit is used to acquire channel signals within the preset range of the touch point; the processor is also used to determine the positions of other touch points based on the channel signals within the preset range of the touch point, thus obtaining a touch area composed of all touch points. In this way, after determining the touch point position, the channel signals within the preset range of that touch point can be acquired, reducing the amount of channel signals acquired, which is beneficial for reducing data processing volume and improving processing efficiency. Alternatively, regardless of the size of the touch panel, in this embodiment, the front-end recognition circuit acquires the channel signals within the preset range of the touch point, filtering out channel signals from other areas as noise, thus filtering out a large amount of noise data, ensuring processing efficiency, and requiring minimal computing resources.

[0071] In one embodiment, the preset range is positively correlated with the area of ​​the touchable region. Alternatively, the preset range is related to the detection accuracy. When the detection accuracy requires recognizing a larger touchable area, the preset range can be increased. For example, when recognizing a finger, the preset range can be 3mm*3mm; or when recognizing a palm, the preset range can be 5mm*5mm. It is understood that this embodiment only describes an example of setting the preset range; the specific setting can be adjusted according to the specific scenario, and the corresponding solution falls within the protection scope of this disclosure.

[0072] Figure 2 This is a block diagram of a front-end circuit according to an embodiment of the present disclosure. See also: Figure 2 A front-end circuit 20 includes: a transmitting channel module 201, a differential charge amplification module 202, a receiving channel determination module 203, a transmitting channel determination module 204, and a touch area acquisition module 205.

[0073] The differential charge amplification module 202 is electrically connected to the touch panel 10 and the receiving channel determination module 203, respectively; the transmitting channel module determination module 204 is electrically connected to the receiving channel determination module 203 and the touch area acquisition module 205, respectively; the transmitting channel module 201 is electrically connected to the transmitting channel determination module 204, the touch area acquisition module 205 and the touch panel 10, respectively.

[0074] The transmission channel module 201 is used to output detection signals of different frequencies to each channel of the touch panel 10 respectively;

[0075] The differential charge amplifier module 202 is used to perform differential processing and amplification processing on the channel signals of two adjacent receiving channels in the touch panel 10 to obtain a differential signal;

[0076] The receiving channel determination module 203 is used to determine the receiving position of the contact in the receiving channel based on the differential signal and a preset differential threshold.

[0077] The transmission channel determination module 204 is used to determine the transmission position of the contact point based on the detection signal, the voltage signal corresponding to the orthogonal signal and the differential signal corresponding to the detection signal;

[0078] The touch area acquisition module 205 is used to acquire channel signals within a preset range of the touch point in order to determine the touch area where the touch point is located.

[0079] Thus, the front-end circuit 20 of this embodiment can amplify and differentially amplify the received channel signal by setting the differential charge amplification module 202, thereby avoiding the influence of common-mode signal and noise signal on the channel signal and improving the accuracy of the acquired signal; in addition, after determining the contact position, this embodiment can acquire the channel signal within a preset range of the contact, which can reduce the amount of channel signal acquired, which is beneficial to reduce the amount of data processing and improve processing efficiency.

[0080] In this embodiment, the transmitting module 201 can adopt a multi-frequency parallel driving scheme, simultaneously transmitting signals of different frequencies to the transmitting channel electrodes of the touch panel, with each transmitting channel corresponding to a transmitting signal of one frequency. Thus, this embodiment can improve the driving speed through multi-frequency parallel driving. The transmitting signals of different frequencies are coupled to the receiving channel electrode via the mutual inductance capacitor Cm between the transmitting channel electrode and the receiving channel electrode to generate a detection signal, i.e., a channel signal. In this embodiment, the transmitting module can be implemented using an analog circuit structure, which has the advantages of low power consumption and small area compared to using a Direct Digital Frequency Synthesis (DDFS) module to generate signals of different frequencies.

[0081] Figure 3This is a block diagram of a differential charge amplification module according to an embodiment of the present disclosure. See also: Figure 3 The differential charge amplification module 202 includes: a charge amplification unit 301, a differential amplification unit 302, and a programmable gain amplification unit 303.

[0082] The charge amplification unit 301 is used to perform differential processing on the channel signals of two adjacent receiving channels in the touch panel to obtain a differential initial signal. By performing differential processing on the two channel signals, the charge amplification unit 301 can eliminate the common-mode signal of the touch panel, thereby obtaining a differential initial signal that only represents the characteristics of the channel signals.

[0083] The differential amplifier unit 302 is used to amplify the differential initial signal to obtain a differential amplified signal. Amplifying the differential initial signal by the differential amplifier unit 302 can improve the signal-to-noise ratio of the differential initial signal, eliminate or mitigate the interference of noise signals on the differential initial signal, and facilitate subsequent accurate position extraction.

[0084] The programmable gain amplifier unit 303 is used to amplify the differential amplified signal to obtain the aforementioned differential initial signal. The programmable gain amplifier unit 303 can adjust the amplification gain according to the size of the touch panel, thereby making the differential charge amplifier module 202 suitable for touch panels of different sizes and improving its applicability.

[0085] Figure 4 This is a circuit diagram of a charge amplification unit according to an embodiment of the present disclosure. See also: Figure 4 The charge amplification unit 301 includes a first amplifier A1, a first resistor R1, and a first capacitor C1. The non-inverting input ("+") of the first amplifier A1 receives the common-mode level Vcm, and the inverting input ("-") of the first amplifier A1 is electrically connected to the first terminals of the first resistor R1 and the first capacitor C1, respectively, and receives the channel signal Q. RX <n>< / n> The output terminal of the first amplifier A1 is electrically connected to the second terminal of the first resistor R1 and the second terminal of the first capacitor C1, respectively, and outputs a differential initial signal V. RX <n>< / n> .

[0086] In this embodiment, Figure 4 The charge amplification unit 301 shown constitutes an operational amplifier RC integrator circuit. Its principle is: when the channel signal Q... RX <n>< / n> Integration is performed when the common-mode level is greater than or equal to Vcm, thereby converting the charge into a voltage, i.e., the differential initial signal V. RX <n>< / n> .

[0087] It should be noted that the product of the first resistor R1 and the first capacitor C1 adjusts the time constant of the RC integrator circuit of the aforementioned operational amplifier. The resistance value of the first resistor R1 and the capacitance value of the first capacitor C1 can be set according to specific scenarios. When the time constant of the first resistor R1 and the first capacitor C1 can be adjusted, the corresponding solution falls within the protection scope of this disclosure.

[0088] Figure 5 Here is a circuit diagram of a differential amplifier unit according to an embodiment of this disclosure. See also: Figure 5 The differential amplifier unit 302 includes: a second amplifier A2, a third amplifier A3, a fourth amplifier A4, a resistor array Rs, a second resistor R2, and a third resistor R3.

[0089] The non-inverting input of the second amplifier A2 receives the channel signal V from the current stage. RX <n>< / n> The inverting input terminal of the second amplifier A2 is electrically connected to the resistor array Rs, and the output terminal of the second amplifier is also electrically connected to the resistor array Rs.

[0090] The non-inverting input of the third amplifier A3 receives the channel signal V from the next stage. RX<N+1> The inverting input terminal of the third amplifier A3 is electrically connected to the resistor array Rs, and the output terminal of the third amplifier A3 is electrically connected to the resistor array Rs.

[0091] The inverting input of the fourth amplifier A4 is electrically connected to the first terminal of the resistor array Rs and the second resistor R2, respectively. The non-inverting input of the fourth amplifier A4 is electrically connected to the first terminal of the resistor array Rs and the third resistor Rs, respectively. The output of the fourth amplifier A4 is electrically connected to the second terminal of the second resistor Rs and outputs a differential amplified signal. The second terminal of the third resistor R3 receives the common-mode level Vcm.

[0092] It should be noted that the resistor array Rs can be set according to the specific scenario.

[0093] In one example, a resistor is connected in series between the inverting input and output of the second amplifier A2, and this resistor is then electrically connected to the inverting input of the fourth amplifier A3; a resistor is also connected in series between the inverting input and output of the third amplifier A3, and this resistor is then electrically connected to the non-inverting input of the fourth amplifier A3. Thus, the second amplifier A2 and the resistor can form an amplifier circuit, and the third amplifier A3 and the resistor can form an amplifier circuit.

[0094] In another example, the resistor array Rs may include multiple switches and multiple resistors. The second amplifier A2 and the third amplifier A3 can share these switches and resistors. The resistors can be connected in series and then connected across the inverting input and output terminals of both amplifiers A2 and A3. Each switch is connected in parallel with its corresponding resistor; when the switch is closed, the resistor is short-circuited. By adjusting the switching state of the switches, the equivalent resistance value of the multiple resistors can be adjusted, thereby synchronously adjusting the amplification ratio of the two amplifier circuits. In other words, a technician can configure the circuit configuration of the resistor array according to the specific scenario, and the corresponding scheme falls within the protection scope of this disclosure.

[0095] See also Figure 5 The differential amplifier unit 302 can output the current stage channel signal V. RX <n>< / n> and the channel signal V of the next stage RX<N+1> Charge amplification and differential amplification are performed to obtain the differential amplified signal V. diff <n>< / n> Considering the large size of the touch panel, which may result in significant common-mode noise, and the fact that the delays between adjacent channels are almost identical (i.e., in this example, the delays between adjacent channels are approximately the same), differential operations on the signals of adjacent channels can eliminate common-mode noise and most of the delay differences, thereby increasing the proportion of effective signal in the channel signals.

[0096] Figure 6 Here is a circuit diagram of a programmable gain amplifier unit according to an embodiment of this disclosure. See also: Figure 6 The programmable gain amplifier unit 303 includes a fifth amplifier A5, a fifth resistor R5, and an adjustable resistor Rt.

[0097] The non-inverting input of the fifth amplifier A5 receives the differential amplified signal V. diff <n>< / n> The inverting input terminal of the fifth amplifier A5 is electrically connected to the second terminal of the fifth resistor R5 and the first terminal of the adjustable resistor Rt, respectively. The output terminal of the fifth amplifier A5 is electrically connected to the second terminal of the adjustable resistor Rt and outputs the differential initial signal V. OUT <n>< / n> .

[0098] Understandably, the fifth amplifier A5, the fifth resistor R5, and the adjustable resistor Rt can form a proportional amplifier. By adjusting the resistance value of the adjustable resistor Rt, the amplification factor of the above proportional amplifier can be adjusted, thereby achieving the effect of adjusting the ratio between the differential amplified signal and the differential initial signal.

[0099] In one example, the adjustable resistor Rt mentioned above may include a sliding resistor Rt, in which case... Figure 6 The circuit of the programmable gain amplifier unit shown can be transformed into Figure 7 The circuit shown.

[0100] In another example, the adjustable resistor Rt may include multiple resistors and corresponding switches for each resistor. The multiple resistors are connected in series and then in parallel between the inverting input and output of the fifth amplifier. The switches corresponding to each resistor are connected in parallel across the resistors. Upon receiving a switching control signal, the control terminals of each switch close to short-circuit the corresponding resistor, thereby adjusting the equivalent resistance and the amplification factor of the proportional amplifier, thus adjusting the ratio between the differential amplified signal and the differential initial signal. Figure 6 The circuit of the programmable gain amplifier unit shown can be transformed into Figure 8 The circuit shown. It is understandable that... Figure 8 The example illustrates a scenario with 4 resistors (Rt1, Rt2, Rt3, Rt4) and 4 switches (PGS0, PGS1, PGS2, PGS3). The number of resistors and switches can be adjusted according to the specific scenario, and the corresponding solution falls within the protection scope of this disclosure.

[0101] Understandably, Figure 8 The control terminals of each switch can be electrically connected to the processor of the front-end identification circuit, enabling switch control based on the processor's control signals. That is, the processor can determine the amplification factor and, based on that factor, determine which switches to close, thus adjusting the amplification factor. Alternatively, the switch control terminals can also be controlled via digital codes, each corresponding one-to-one with a switch. A digital code configured as 1 closes the switch to short-circuit the resistor, while a digital code configured as 0 opens the switch, similarly adjusting the resistance value. Technicians can select the appropriate control method for the switches based on the specific scenario, and the corresponding solution falls within the protection scope of this disclosure.

[0102] It should be noted that in this embodiment, the programmable gain amplifier unit can amplify the differential signal V. diff <n>< / n> To avoid the detection results being affected by the large size of the touch panel and the weak channel signal.

[0103] Figure 9 This is a block diagram of a receiving channel determination module according to an embodiment of the present disclosure. See also: Figure 9 The receiving channel determination module includes a voltage-to-current conversion unit 901, a first multiplier unit 902, a first integrator unit 903, and a receiving channel determination unit 904.

[0104] Voltage-to-current conversion unit 901 is used to convert the differential initial signal V OUT <n>< / n> Converted to differential current signal I 1 <n>< / n> The first multiplier unit 902 is used to process the differential current signal I. 1 <n>< / n> The intermediate current signal I is obtained through processing. 2 <n>< / n> The first integrator unit 903 is used to process the intermediate current signal I.2 <n>< / n> The integral voltage V is obtained by performing integration. INT1 <n>< / n> The receiving channel determination unit 904 is used to compare the integrated voltage V. INT1 <n>< / n> and preset difference threshold V REF1 The contact point is located at the receiving position V in the receiving channel. J_RX <n>< / n> .

[0105] It should be noted that the preset difference threshold V REF1 It can be preset, and the settings can be adjusted and tested according to the specific scenario if it can be distinguished as triggered or not. No limit is set here.

[0106] In one example, the voltage-to-current conversion unit 901 can be implemented using an operational amplifier differentiator circuit.

[0107] See Figure 10 At this time, the current output by the voltage-to-current conversion unit 901 is:

[0108]

[0109] In one example, the first multiplier unit 902 can be implemented using a proportional amplifier circuit, which can be used with... Figure 6 The programmable gain amplifier unit shown is similar, except that the resistance values ​​of the two resistors may be different, thus adjusting the amplification factor differently. The resistance values ​​can be set according to the specific scenario, and the corresponding scheme falls within the protection scope of this disclosure.

[0110] In one example, the first integrator unit 903 can be implemented using an integrating circuit, which can be connected with... Figure 3 The charge amplification unit 301 shown is similar, except that the values ​​of the first resistor R1 and the first capacitor C1 may be different, that is, the time constants are different. The resistance values ​​can be set according to the specific scenario, and the corresponding scheme falls within the protection scope of this disclosure.

[0111] In one example, the receive channel determination unit 904 can be implemented using a comparator. In another example, this comparator can be implemented using an operational amplifier, for example, with the integrated voltage V input to the non-inverting input of the operational amplifier. INT1 <n>< / n> The inverting input terminal inputs a preset differential threshold V. REF1 When the integral voltage V INT1 <n>< / n> Greater than the preset difference threshold V REF1 When the operational amplifier outputs a high level, it indicates that there is a contact in this row. When the integral voltage V... INT1 <n>< / n> Less than or equal to the preset difference threshold V REF1At this time, the operational amplifier outputs a low level to indicate that there are no contacts in this row. Technicians can configure the circuit implementation of the receiving channel determination unit 904 according to specific scenarios, and the corresponding scheme falls within the protection scope of this disclosure.

[0112] Figure 11 This is a block diagram of a transmission channel determination module according to an embodiment of the present disclosure. See also: Figure 11 The launch channel determination module 204 includes a second multiplier unit 111, a second integrator unit 112, and a launch channel determination unit 113.

[0113] The second multiplier unit 111 is used to calculate the current stage's channel signal Q. RX <n>< / n> and the channel signal Q of the next stage RX<N+1> The differential current signal I output by the receiving channel determination module 203 1 <n>< / n> After multiplication, the current amplified signal I is obtained. IN <n>< / n> ;

[0114] The second integrator unit 112 is used to amplify the current signal I. IN <n>< / n> By performing integration, the integrated voltage V is obtained. INT2 <n>< / n> ;

[0115] The transmission channel determination unit 113 is used to determine the transmission channel based on the first preset transmission threshold V. REF2 Second preset transmission threshold V REF3 and integral voltage V INT2 <n>< / n> The transmission channel where the contact is located is determined, and the transmission position V is obtained. J_TX <n>< / n> .

[0116] In one example, the second multiplier unit 111 can acquire the current stage's channel signal Q. RX <n>< / n> and differential current signal I 1 <n>< / n> The product of these factors is used to select the differential current signal corresponding to the current channel; and the channel signal Q of the next stage is obtained. RX<N+1> and differential current signal I 1 <n>< / n> The product of the two differential current signals is used to select the differential current signal corresponding to the next stage channel; then, the common current signal of the two differential current signals is obtained to get the current amplification signal I. IN <n>< / n> For the reasons stated above, the structure of the second multiplier unit 111 is as follows: Figure 12 As shown.

[0117] Figure 12It includes a first multiplication subunit, a second multiplication subunit, and a third multiplication subunit. Each subunit can be implemented using the same multiplier, which can be implemented using a proportional amplifier circuit similar to the first multiplier unit 902. The difference is that the resistance values ​​of the two resistors may be different, thus adjusting the amplification factor differently. The resistance values ​​can be set according to the specific scenario, and the corresponding scheme falls within the protection scope of this disclosure.

[0118] In one example, the second integrator unit 112 can be implemented using an integrating circuit, which can be connected with... Figure 3 The charge amplification unit 301 shown is similar, except that the values ​​of the first resistor R1 and the first capacitor C1 may be different, that is, the time constants are different. The resistance values ​​can be set according to the specific scenario, and the corresponding scheme falls within the protection scope of this disclosure.

[0119] In one example, the transmit channel determination unit 113 can be implemented using two comparators. The comparators can be implemented using the circuit structure of the receive channel determination unit 904. The two input data of the first comparator are a first preset transmit threshold V. REF2 and integral voltage V INT2 <n>< / n> When the integral voltage V INT2 <n>< / n> Greater than the first preset transmission threshold V REF2 When the first comparator outputs a high level, the two input data of the second comparator are the second preset emission threshold V. REF3 and integral voltage V INT2 <n>< / n> When the integral voltage V INT2 <n>< / n> Less than or equal to the first preset emission threshold V REF2 When the signal is high, the first comparator outputs a low level. Thus, the transmitting unit 113 can select the channel corresponding to the high level and determine the transmitting channel where the contact is located.

[0120] Figure 13 This is a timing diagram of a front-end circuit according to an embodiment of the present disclosure. See also: Figure 13 After receiving the channel signal, the front-end circuit obtains the receiving position of the receiving channel where the touch point is located through the receiving channel determination module 203. Furthermore, the transmitting channel determination module 204 determines the transmitting position of the transmitting channel where the touch point is located. These transmitting and receiving positions constitute the actual position of the touch point. The processor of the front-end recognition circuit can determine the preset range of the touch point based on its position and send it to the touch area acquisition module 205. The touch area acquisition module 205 can acquire the channel signal within the preset range of the touch point and send it to the processor. At this time, the processor can calculate the coordinates of all touch points based on the channel signal within the preset range and map them onto the display screen of the display device.

[0121] It should be noted that the first preset transmission threshold V REF2 Second preset emission threshold VREF3 It can be preset, for example, by first testing the display device and adjusting the first preset emission threshold V. REF2 Second preset emission threshold V REF3 If the transmission channel where the contact is located can be identified, the corresponding solution falls within the protection scope of this disclosure.

[0122] In this embodiment, the acquisition process described above can be implemented in stages. Specifically, when the first frame of data completes the first step and begins the second step, the second frame of data immediately begins the first step; when the first frame of data completes the second step and begins the third step, the second frame of data immediately begins the second step, and the third frame of data immediately begins the first step; when the first frame of data completes the third step and begins the fourth step, the second frame of data immediately begins the third step, the third frame of data immediately begins the second step, and the third frame of data immediately begins the first step; when the first frame of data completes the fourth step and begins the first step of the next cycle, the second frame of data immediately begins the fourth step, the third frame of data immediately begins the third step, and the third frame of data immediately begins the second step. If multiple contacts exist, the last three steps are repeated until all contacts have been calculated. In this way, this embodiment ensures that each module of each front-end circuit remains operational, maximizing the utilization of hardware resources.

[0123] The computational complexity comparison between the front-end recognition circuit provided in this embodiment and front-end recognition circuits in related technologies is as follows: Figure 14 As shown. See also Figure 14 As the size of the display device increases, i.e., the number of receiving channels increases, the computational complexity of the front-end recognition circuit in this embodiment and in related technologies both increase. However, the computational complexity of the front-end recognition circuit in this embodiment is approximately 10^3, while the computational complexity in related technologies is approximately 10^4 to 10^5. In other words, the computational complexity of the front-end recognition circuit in this embodiment is far lower than that in related technologies. Alternatively, compared to front-end recognition circuits in related technologies, the front-end recognition circuit in this embodiment has the advantages of low computational complexity, low hardware resource consumption, and high speed.

[0124] Based on the front-end recognition circuit provided in the embodiments of this disclosure, the embodiments of this disclosure also provide a touch area positioning method, see [link to relevant documentation]. Figure 15 ,include:

[0125] Step 151: Obtain the transmission and reception positions of the contact points;

[0126] For details on step 151, please refer to the scheme for obtaining the transmission and reception positions by the front-end identification circuit. The processor in the front-end identification circuit communicates with the front-end circuit to obtain the transmission and reception positions of the contact.

[0127] Step 152: Determine the preset range of the contact point based on the transmitting position and the receiving position.

[0128] In step 152, the aforementioned preset range is positively correlated with the area of ​​the touchable region. In other words, the preset range is related to the detection accuracy. When the detection accuracy requires recognizing a larger touchable area, the preset range can be increased. For example, when recognizing a finger, the preset range can be 3mm*3mm; or when recognizing a palm, the preset range can be 5mm*5mm. The processor can determine the preset range of the touch point based on the transmitting and receiving positions of the touch point.

[0129] Step 153: Obtain the channel signal within the preset range of the contact point.

[0130] In step 153, after the preset range is determined, the channels within that preset range are known. The front-end circuit can acquire the channel signals of each channel within the preset range.

[0131] Step 154: Determine the positions of other touch points based on the channel signals within the preset range to obtain the touch area.

[0132] In step 154, the processor can determine the positions of other touch points based on the channel signals within a preset range, thereby obtaining the touch area. It is understood that the aforementioned touch area refers to the coordinate positions of the touch points on the display screen; therefore, the touch points can be directly displayed on the display screen of the display device.

[0133] Since the description of the front-end recognition circuit scheme also includes the description of the processor's data processing, please refer to the relevant content for details, and will not be repeated here.

[0134] The terminology used in this disclosure is for the purpose of describing particular embodiments only and is not intended to be limiting of the disclosure. Unless otherwise defined, the technical or scientific terms used in this disclosure should be understood in their ordinary sense by one of ordinary skill in the art to which this disclosure pertains. The words “a” or “one” and similar terms used in this disclosure and the claims do not indicate a limitation of quantity, but rather indicate the presence of at least one. “A plurality” means at least two. The words “comprising” or “including” and similar terms mean that the element or object preceding “comprising” or “including” covers the element or object listed following “comprising” or “including” and its equivalents, and does not exclude other elements or objects. The words “connected” or “linked” and similar terms are not limited to physical or mechanical connections and can include electrical connections, whether direct or indirect. The singular forms “a,” “the,” and “the” used in this disclosure and the appended claims are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0135] For the method embodiments, since they basically correspond to the apparatus embodiments, the relevant parts can be referred to in the description of the apparatus embodiments. The method embodiments and apparatus embodiments complement each other.

[0136] The above description is merely a preferred embodiment of this disclosure and is not intended to limit this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the scope of protection of this disclosure.

Claims

1. A front-end circuit suitable for a touch panel, characterized in that, The front-end circuit includes: a differential charge amplification module, a receiving channel determination module, a transmitting channel determination module, a transmitting channel module, and a touch area acquisition module; the differential charge amplification module is electrically connected to the touch panel and the receiving channel determination module; the transmitting channel determination module is electrically connected to the receiving channel determination module and the touch area acquisition module; the transmitting channel module is electrically connected to the transmitting channel determination module, the touch area acquisition module, and the touch panel. The transmission channel module is used to output detection signals of different frequencies to each channel of the touch panel respectively; The differential charge amplification module is used to perform differential processing and amplification on the channel signals of two adjacent receiving channels in the touch panel to obtain a differential signal; The receiving channel determination module is used to determine the receiving position of the contact in the receiving channel based on the differential signal and a preset differential threshold. The transmission channel determination module is used to determine the transmission position of the contact point based on the detection signal, the orthogonal signal corresponding to the detection signal, and the voltage signal corresponding to the differential signal. The touch area acquisition module is used to acquire channel signals within a preset range of the touch point in order to determine the touch area where the touch point is located. The transmission channel determination module includes a second multiplier unit, a second integrator unit, and a transmission channel determination unit. The second multiplier unit is used to multiply the differential current signal output by the receiving channel determination module according to the channel signal of the current stage and the channel signal of the next stage to obtain the current amplified signal; The second integrator unit is used to integrate the current amplified signal to obtain the integrated voltage; The transmission channel determination unit is used to determine the transmission channel where the contact is located based on the first preset transmission threshold, the second preset transmission threshold and the integrated voltage, and thus obtain the transmission position.

2. The front-end circuit according to claim 1, characterized in that, The differential charge amplification module includes a charge amplification unit, a differential amplification unit, and a programmable gain amplification unit; The charge amplification unit is used to perform differential processing on the channel signals of two adjacent receiving channels in the touch panel to obtain a differential initial signal; The differential amplification unit is used to amplify the differential initial signal to obtain a differential amplified signal; The programmable gain amplification unit is used to amplify the differential amplified signal to obtain the differential initial signal.

3. The front-end circuit according to claim 2, characterized in that, The charge amplification unit includes a first amplifier, a first resistor, and a first capacitor; The non-inverting input of the first amplifier receives a common-mode level, the inverting input of the first amplifier is electrically connected to the first end of the first resistor and the first end of the first capacitor respectively and receives a channel signal, and the output of the first amplifier is electrically connected to the second end of the first resistor and the second end of the first capacitor respectively and outputs a differential initial signal.

4. The front-end circuit according to claim 2, characterized in that, The differential amplifier unit includes a second amplifier, a third amplifier, a fourth amplifier, a resistor array, a second resistor, and a third resistor; The non-inverting input of the second amplifier receives the channel signal of the current stage, the inverting input of the second amplifier is electrically connected to the resistor array, and the output of the second amplifier is electrically connected to the resistor array. The non-inverting input of the third amplifier receives the channel signal from the next stage, the inverting input of the third amplifier is electrically connected to the resistor array, and the output of the third amplifier is electrically connected to the resistor array. The inverting input terminal of the fourth amplifier is electrically connected to the resistor array and the first terminal of the second resistor, respectively. The non-inverting input terminal of the fourth amplifier is electrically connected to the resistor array and the first terminal of the third resistor, respectively. The output terminal of the fourth amplifier is electrically connected to the second terminal of the second resistor and outputs a differential amplified signal. The second terminal of the third resistor receives the common-mode level.

5. The front-end circuit according to claim 2, characterized in that, The programmable gain amplifier unit includes a fifth amplifier, a fifth resistor, and an adjustable resistor; The non-inverting input of the fifth amplifier receives the differential amplified signal, the inverting input of the fifth amplifier is electrically connected to the second terminal of the fifth resistor and the first terminal of the adjustable resistor, and the output of the fifth amplifier is electrically connected to the second terminal of the adjustable resistor and outputs the differential initial signal.

6. The front-end circuit according to claim 5, characterized in that, The adjustable resistor includes a sliding resistor; or... The adjustable resistor includes multiple resistors and a switching switch corresponding to each resistor. The multiple resistors are connected in series and then in parallel between the inverting input and output of the fifth amplifier. The switching switch corresponding to each resistor is connected in parallel across the two ends of each resistor. The control terminal of each switching switch closes to short-circuit the corresponding resistor after receiving a switching control signal.

7. The front-end circuit according to claim 5, characterized in that, The receiving channel determination module includes a voltage-to-current conversion unit, a first multiplier unit, a first integrator unit, and a receiving channel determination unit; The voltage-to-current conversion unit is used to convert the differential initial signal into a differential current signal; The first multiplier unit is used to process the differential current signal to obtain an intermediate current signal; The first integrator unit is used to integrate the intermediate current signal to obtain an integrated voltage; The receiving channel determination unit is used to compare the integrated voltage and the preset differential threshold to obtain the receiving position of the contact in the receiving channel.

8. The front-end circuit according to claim 1, characterized in that, The preset range is positively correlated with the area of ​​the touch area.

9. A front-end identification circuit, characterized in that, Includes the front-end circuitry and processor as described in any one of claims 1 to 8; the front-end circuitry and the processor are electrically connected; The processor is used to determine a preset range of the contact point based on the transmission and reception positions of the contact point, and send the preset range to the front-end circuit; The front-end circuit is used to acquire channel signals within a preset range of the contact point; The processor is also used to determine the positions of other touch points based on the channel signals within a preset range of the touch points, thereby obtaining a touch area composed of all the touch points.

10. A display device, characterized in that, It includes the front-end recognition circuit and the touch panel as described in claim 9; the front-end recognition circuit is electrically connected to the touch panel.

11. A method for locating a touch area, characterized in that, Based on the front-end recognition circuit as described in claim 9, the method includes: Obtain the transmit and receive positions of the contact points; The preset range of the contact point is determined based on the transmitting position and the receiving position; Acquire channel signals within a preset range of the contact point; The positions of other touch points are determined based on the channel signals within a preset range, thus obtaining the touch area.

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