TWI770763B - Touch sensing device and sensing method thereof - Google Patents

Abstract

A touch sensing device and a sensing method thereof are provided. The touch sensing device includes a driving voltage selector, a reference voltage selector, a voltage detecting circuit and a controller. The driving voltage selector provides a plurality of driving voltages in sequential to charge a touch sensing pad during a noise sensing time period for respectively generating a plurality of charging voltages. The reference voltage generator sequentially generates a plurality of reference voltages corresponding to the driving voltages. The voltage detecting circuit sequentially compares the driving voltages and the charging voltages to generate a plurality of sensing result. The controller sets a touch sensing strategy according to the sensing results.

Description

Touch sensing device and sensing method thereof

The present invention relates to a touch sensing device and a sensing method thereof, and more particularly, to a touch sensing device and a sensing method which can improve the noise value sensing accuracy.

In today's electronic devices, in order to improve a more convenient human-machine interface, a touch sensing device has become an essential component of the electronic device.

In the prior art, in order to eliminate the interference caused by external noise, a single driving voltage is applied to the touch panel of the touch sensing device, and a single reference voltage that is the same as the driving voltage is applied. When external noise enters the system-controlled sensing device, it can be learned by comparing the difference between the voltage on the touch panel and the reference voltage.

However, in the prior art, in the electronic device system, different data paths will bring different frequency responses, and the difference in the frequency response will cause errors in the sensed voltage difference, resulting in The noise value senses errors in judgment.

The present invention provides a touch sensing device and a sensing method thereof, which can more accurately estimate the noise value and optimize the touch detection result.

The touch sensing device of the present invention includes a driving voltage selector, a reference voltage selector, a voltage detection circuit and a controller. The driving voltage selector sequentially provides a plurality of different driving voltages to charge the touch panel during the noise sensing period to generate a plurality of charging voltages respectively. The reference voltage selector corresponds to the driving voltage to provide different reference voltages in sequence during the noise sensing period. The voltage detection circuit is coupled to the touch panel, and sequentially compares the charging voltage with the corresponding reference voltage during the noise sensing period to generate a plurality of sensing results. The controller is coupled to the voltage detection circuit, and sets the touch sensing strategy according to the sensing result.

The touch sensing method of the present invention includes: sequentially providing different multiple driving voltages to charge the touch panel during the noise sensing period to generate the multiple charging voltages respectively; corresponding to the driving voltages during the noise sensing period to separately Providing a plurality of different reference voltages in sequence; comparing the charging voltages with the corresponding reference voltages in sequence during the noise sensing period to generate a plurality of sensing results; and setting a touch sensing strategy according to the sensing results .

Based on the above, the touch sensing device of the present invention utilizes a plurality of different driving voltages to perform noise value testing during the noise sensing period, so that the noise from different data paths can be sufficiently show up. The touch sensing device then formulates a touch sensing strategy according to the sensing results obtained corresponding to different driving voltages, which can optimize the accuracy of the measurement and control actions and improve the performance of the touch sensing device.

Please refer to FIG. 1 , which is a schematic diagram of a touch sensing device according to an embodiment of the present invention. The touch sensing device 100 includes a driving voltage selector 110 , a reference voltage selector 120 , a voltage detection circuit 130 and a controller 140 . The driving voltage selector 110 is coupled to the touch panel SX. The driving voltage selector 110 receives a plurality of candidate voltages V1 ˜VN, and selects each candidate voltage V1 ˜VN in sequence during the noise sensing period to provide a plurality of different driving voltages to the touch panel SX. The control board SX is charged to generate a plurality of charging voltages VCP, respectively. The reference voltage selector 120 is coupled to the voltage detection circuit 130 and receives the candidate voltages V1 ˜VN. During the noise sensing period, the reference voltage selector 120 sequentially provides a plurality of different reference voltages VREF to the voltage detection circuit 130 corresponding to the driving voltages provided by the driving voltage selectors 110 respectively. In this embodiment, the voltage levels of any two of the voltages V1 to VN to be selected are different.

In the present embodiment, during the noise sensing period, the voltage detection circuit 130 sequentially compares the charging voltage VCP with the corresponding reference voltage VREF, and respectively generates a plurality of sensing results QVC. The voltage detection circuit 130 is coupled to the controller 140 and transmits the sensing result QVC to the controller 140 . The controller 140 can set the touch sensing strategy of the touch sensing device 100 according to the received multiple sensing results QVC.

Please note that, in the present embodiment, the touch sensing device 100 performs the noise value sensing operation through driving voltages of different voltage levels in sequence in time division and in conjunction with the reference voltage VREF corresponding to the driving voltage. In an integrated circuit, the voltage of different levels reaches the target voltage through different data paths during the operation inside the chip. Different data paths also represent different resistor-capacitor (RC) loading effects. Therefore, when the external voltage difference is introduced into the analog front end (AFE) circuit of the voltage detection circuit 130 , there will be different frequency response.

The voltage detection circuit 130 can reflect the above-mentioned frequency response by correspondingly generating a plurality of sensing results QVC. The controller 140 can collect enough sensing results QVC, and set the touch sensing strategy of the touch sensing device 100 according to the sensing results QVC.

Here, in the touch sensing strategy formulated by the controller 140 , the frequency hopping of the operating frequency can be performed in the touch sensing action according to the noise values of the touch sensing device 100 corresponding to the states of different driving voltages. (frequency hopping) action, adjust the number of sensing sampling points, or adjust the number of parameters to switch to noise mode. For example, the controller 140 can select an operating frequency with a relatively low noise value according to the sensing result QVC, so that the touch sensing device 100 can perform operations. The controller 140 can also reduce the influence of the noise on the touch sensing device 100 by adjusting the algorithm of the software, using mechanisms such as software filters and de-bouncing.

In this embodiment, during the noise sensing period, the driving voltage and the reference voltage VREF provided by the driving voltage selector 110 and the reference voltage selector 120 at the same time point may be the same. That is to say, corresponding to this time point, under the condition of no noise interference, the voltage detection circuit 130 can compare the driving voltage and the reference voltage VREF and should generate a sensing result QVC of 0. However, in actual operation, the driving voltage and/or the reference voltage VREF may carry a certain noise value, and the voltage detection circuit 130 can sense the noise value by comparing the driving voltage and the reference voltage VREF, and The sensing result QVC is generated accordingly.

In this embodiment, in terms of hardware structure, the driving voltage selector 110 may be a voltage selector, and according to the control signal during the noise sensing period, one of the voltages V1 to VN to be selected can be selected in sequence. generate driving voltage. The reference voltage selector 120 can be another voltage selector, and also selects one of the candidate voltages V1 ˜ VN in sequence to generate the reference voltage VREF according to the control signal during the noise sensing period. The voltage detection circuit 130 may be constructed by a differential amplifier. The controller 140 may be a processor with computing capability. Alternatively, the controller 140 can be designed through a hardware description language (Hardware Description Language, HDL) or any other digital circuit design methods well known to those skilled in the art, and can be designed through a field programmable logic gate array ( Field Programmable Gate Array, FPGA), complex programmable logic device (Complex Programmable Logic Device, CPLD) or application-specific integrated circuit (Application-specific Integrated Circuit, ASIC) way to realize the hardware circuit.

Please refer to FIG. 2 below. FIG. 2 is a flowchart illustrating an operation of the touch sensing device in a noise sensing period according to an embodiment of the present invention. In step S210, the touch sensing device can set a search sequence and initialize the index value i=-1, wherein the search sequence has n elements, n is a positive integer greater than 1, and the search sequence [n]= {V1, V2, …, VN}, V1~VN correspond to multiple voltages to be selected. Next, in step S220, the touch sensing device increments the index value i by 1, and in step S230, the touch sensing device makes the driving voltage and the reference voltage=search order[i]. That is, when i=0, the driving voltage and the reference voltage can be equal to V1; when i=1, the driving voltage and the reference voltage can be equal to V2, and so on.

In step S240, the touch sensing device performs a sensing action, and in step S250, a sensing result is obtained.

Next, in step S260, the touch sensing device may determine whether i is less than n. If the determination result is yes, it means that the noise sensing operation is not completed, and the touch sensing device may return to step S220 to continue to perform the noise sensing operation. On the contrary, when the judgment result is NO, it means that the noise sensing operation has been completed. The touch sensing device can set the touch sensing strategy according to the obtained sensing result through the controller (step S270 ).

Incidentally, in the search sequence [n], the voltages V1~VN to be selected can be arranged in ascending or descending manner according to the size of the voltage level, or they can be arranged arbitrarily without depending on the size of the voltage level. Fixed limits.

In this embodiment, the manipulation of steps S210 to S270 may be completed by a controller in the touch sensing device. The look-up sequence can then be recorded in a look-up table, which can be stored in any form of memory that can be accessed by the controller.

Please refer to FIGS. 3A and 3B below. FIGS. 3A and 3B are action waveform diagrams of different implementations of the noise sensing operation of the touch sensing device in different embodiments of the present invention. In FIG. 3A , the noise sensing action of the touch sensing device can be performed by continuously changing the voltage levels of the driving voltage and the reference voltage. Wherein, in the first time interval NLC1, the touch sensing device can make the driving voltage and the reference voltage equal to the candidate voltage V1; in the next second time interval NLC2, the touch sensing device can make the driving voltage and the reference voltage equal to the voltage V1 to be selected. The reference voltage is equal to the candidate voltage V2; and, in the next third time interval NLC3, the touch sensing device can make the driving voltage and the reference voltage equal to the candidate voltage V3. Wherein, the first time interval NLC1 to the third time interval NLC3 may occur continuously.

In addition, in FIG. 3B, the touch sensing device can make the driving voltage and the reference voltage equal to the relatively low candidate voltage V1 in the first time interval NLC1, and perform the noise sensing operation. Then, in the capacitive sensing time SC1 after the first time interval NLC1, the touch sensing device can perform a normal touch sensing action, and sense the touch by sensing the change of the capacitance value on the touch panel. Touched state of the control panel. The touch sensing device can make the driving voltage and the reference voltage equal to the high candidate voltage VN in the subsequent Nth time interval NLCN, and perform the noise sensing operation. In the capacitive sensing time SCN after the Nth time interval NLCN, the normal touch sensing action can also be performed.

In FIG. 3B , the noise sensing operations corresponding to the plurality of candidate voltages V1 ˜ VN can be performed in different frame periods.

Please refer to FIG. 4 below. FIG. 4 is a schematic diagram of a circuit structure of a touch sensing device according to another embodiment of the present invention. The touch sensing device 400 includes a driving voltage selector 410 , a reference voltage selector 420 and a voltage detection circuit 430 . The driving voltage selector 410 includes a plurality of switches SW11 to SW1N. The plurality of first terminals of the switches SW11 ˜ SW1N respectively receive the plurality of candidate voltages V1 ˜VN, and the plurality of second terminals of the switches SW11 ˜ SW1N are commonly coupled to the touch panel SX and coupled to the voltage detection circuit 430 . The reference voltage selector 420 includes a plurality of switches SW21 ˜ SW2N. The plurality of first terminals of the switches SW21 ˜ SW2N respectively receive the plurality of candidate voltages V1 ˜VN, and the plurality of second terminals of the switches SW21 ˜ SW2N are commonly coupled to the voltage detection circuit 430 . The driving voltage selector 410 and the reference voltage selector 420 work according to the control signals CTR1 and CTR2 respectively, wherein at most one of the switches SW11 ˜ SW1N can be turned on according to the control signal CTR1 , and at most one of the switches SW21 ˜ SW2N It can be turned on according to the control signal CTR2. During the noise sensing period, the driving voltage selector 410 and the reference voltage selector 420 can select the same candidate voltages V1 ˜VN as the driving voltage and the reference voltage VREF, respectively.

On the other hand, the voltage detection circuit 430 includes a switch SW3, an operational amplifier OP, and a capacitor Cint. The operational amplifier OP has a negative input terminal coupled to the switch SW3, and can receive the charging voltage VCP through the switch SW3. The positive input terminal of the operational amplifier OP receives the reference voltage VREF. The output terminal of the operational amplifier OP generates the sensing result QVC. The capacitor Cint is coupled in series between the output terminal of the operational amplifier OP and the negative input terminal of the operational amplifier OP.

In terms of action details, the driving voltage selector 410 can select one of the candidate voltages V1 to VN (eg, the candidate voltage V1 ) as the driving voltage at the first time, and make the driving voltage charge the touch panel SX, and Thereby, the charging voltage VCP is generated. The reference voltage selector 420 may select one of the candidate voltages V1 to VN (the candidate voltage V1 ) corresponding to the first time as the reference voltage VREF. At the same time, the switch SW3 is turned off.

Then, in the second time after the first time, the switch SW3 is turned on, and the switches SW11 to SW1N are all turned off. At this time, the driving voltage selector 410 stops supplying the driving voltage. The voltage detection circuit 430 can generate the sensing result QVC according to the comparison between the charging voltage VCP on the touch panel SX and the reference voltage VREF.

Incidentally, the touch sensing device 400 can perform a self-capacitance capacitance sensing action. In the capacitance value sensing operation, when the driving voltage selector 410 selects relatively high voltage candidate voltages V1 ˜VN as the driving voltage, the reference voltage selector 420 can select relatively low voltage candidate voltages V1 ˜VN as the driving voltage reference voltage VREF. The action sequence of the touch sensing device 400 in the capacitance value sensing action is the same as the action sequence in the noise sensing action, and details are omitted here.

In this embodiment, the control signals CTR1 and CTR2 may be generated by a controller in the touch sensing device 400 . The implementation details of the controller are described in detail in the embodiment of FIG. 1 , and details are not repeated here.

Please refer to FIG. 5 below. FIG. 5 is a flowchart illustrating a touch sensing method of a touch sensing device according to an embodiment of the present invention. In step S510, during the noise sensing period, different multiple driving voltages are sequentially provided to charge the touch panel to generate multiple charging voltages respectively; in step S520, during the noise sensing period, the corresponding driving voltages are respectively Different multiple selection voltages are provided in sequence; in step S530, the charging voltage is sequentially compared with the corresponding reference voltage during the noise sensing period to generate multiple sensing results; in step S540, according to the sensing The measurement result is used to set the touch sensing strategy.

The implementation details of the above-mentioned multiple steps S510 to S540 have been described in detail in the foregoing multiple embodiments and implementation manners, and will not be repeated here.

To sum up, the touch sensing device of the present invention charges the touch panel by providing a plurality of different driving voltages during the noise sensing period, and provides different reference voltages corresponding to the driving voltages, so as to detect the touch control respectively. The charging voltage on the board is compared and the sensing result is obtained. Based on the sequentially generated driving voltages having a plurality of different voltage levels, the frequency responses of the plurality of data paths in the system to which the touch sensing device belongs can be presented in the sensing result. Therefore, the touch sensing strategy formulated according to the sensing result can be improved to improve the accuracy of touch sensing.

100, 400: touch sensing device 110, 410: drive voltage selector 120, 420: Reference voltage selector 130, 430: Voltage detection circuit 140: Controller Cint: Capacitance CTR1, CTR2: control signal NLC1~NLC3, NLCN: time interval OP: Operational Amplifier QVC: Sensing results S210~S270: Noise sensing steps S510~S530: touch sensing steps SC1, SCN: Capacitive sensing time SW11~SW1N, SW21~SW2N, SW3: switch SX: Trackpad V1~VN: voltage to be selected VCP: charging voltage VREF: reference voltage

FIG. 1 is a schematic diagram of a touch sensing device according to an embodiment of the present invention. FIG. 2 is a flow chart illustrating an operation of the touch sensing device in a noise sensing period according to an embodiment of the present invention. FIG. 3A and FIG. 3B are action waveform diagrams of different implementations of the noise sensing action of the touch sensing device in different embodiments of the present invention. FIG. 4 is a schematic diagram of a circuit structure of a touch sensing device according to another embodiment of the present invention. FIG. 5 is a flowchart illustrating a touch sensing method of a touch sensing device according to an embodiment of the present invention.

100: Touch Sensing Device

110: Drive voltage selector

120: Reference voltage selector

130: Voltage detection circuit

140: Controller

SX: Trackpad

V1~VN: voltage to be selected

VCP: charging voltage

VREF: reference voltage

QVC: Sensing results

Claims (16)

A touch sensing device, comprising: a driving voltage selector for sequentially providing a plurality of different driving voltages in a noise sensing period to charge a touch panel to generate a plurality of charging voltages respectively; a reference voltage selector, corresponding to the driving voltages during the noise sensing period to provide different reference voltages in sequence; A voltage detection circuit, coupled to the touch panel, sequentially compares the charging voltages with the corresponding reference voltages to generate a plurality of sensing results during the noise sensing period; and A controller, coupled to the voltage detection circuit, sets a touch sensing strategy according to the sensing results. The touch sensing device of claim 1, wherein the driving voltage selectors respectively provide the driving voltages to charge the touch panel to generate the respective driving voltages during a plurality of first times during the noise sensing period For the charging voltages, the voltage detection circuit compares the charging voltages with the corresponding reference voltages in a plurality of second times during the noise sensing period to generate the sensing results. The touch sensing device of claim 2, wherein each of the first times does not overlap with each of the corresponding second times. The touch sensing device of claim 2, wherein the driving voltage selector comprises: A plurality of first switches respectively have a plurality of first terminals for respectively receiving a plurality of voltages to be selected, a plurality of second terminals of the first switches are commonly coupled to the voltage detection circuit, and the switches are respectively based on the plurality of first switches A control signal to be turned on or off. The touch sensing device of claim 4, wherein the reference voltage selector comprises: A plurality of second switches respectively have a plurality of first terminals for respectively receiving the voltages to be selected, a plurality of second terminals of the second switches are commonly coupled to the voltage detection circuit, and the switches are respectively based on the plurality of first terminals Two control signals to be turned on or off. The touch sensing device of claim 5, wherein at most one of the first switches is turned on, and at most one of the second switches is turned on. The touch sensing device of claim 5, wherein the controller is used for generating the first control signals and the second control signals. The touch sensing device according to claim 4, wherein the voltage detection circuit comprises: an operational amplifier having a negative input terminal to receive each of the charging voltages, a positive input terminal of the operational amplifier to receive each of the reference voltages, and an output terminal of the operational amplifier to generate the sensing result; a capacitor, coupled in series between the output terminal of the operational amplifier and the negative input terminal of the operational amplifier; and A third switch is coupled in series between the negative input end of the operational amplifier and the touch panel. The touch sensing device of claim 8, wherein the third switch is turned off at the first times and turned on at the second times. The touch sensing device of claim 2, wherein in each of the first times, each of the corresponding driving voltages and each of the reference voltages are the same, and each of the reference voltages in each of the first times corresponds to the corresponding During the second time, the voltage level remains unchanged. The touch sensing device of claim 1, wherein during the noise sensing period, the controller determines a supply order of the driving voltages and the reference voltages according to a search sequence, wherein the search sequence is recorded in a lookup table. A touch sensing method, comprising: During a noise sensing period, a plurality of different driving voltages are sequentially provided to charge a touch panel to generate a plurality of charging voltages respectively; During the noise sensing period, corresponding to the driving voltages, different reference voltages are sequentially provided respectively; During the noise sensing period, the charging voltages are sequentially compared with the corresponding reference voltages to generate a plurality of sensing results; and A touch sensing strategy is set according to the sensing results. The touch sensing method of claim 12, wherein the step of sequentially providing different multiple driving voltages to charge the touch panel during the noise sensing period to generate multiple charging voltages respectively comprises: In a plurality of first times during the noise sensing period, the driving voltages are respectively provided to charge the touch panel to generate the charging voltages respectively; Wherein, during the noise sensing period, the steps of sequentially comparing the charging voltages with the corresponding reference voltages to generate the sensing results include: In a plurality of second times during the noise sensing period, the charging voltages are respectively compared with the corresponding reference voltages to generate the sensing results. The touch sensing method according to claim 13, wherein each of the first times and each of the corresponding second times do not overlap. The touch sensing method of claim 14, wherein in each of the first times, each of the corresponding driving voltages and each of the reference voltages are the same, and each of the reference voltages corresponds to the corresponding each of the reference voltages in each of the first times During the second time, the voltage level remains unchanged The touch sensing method of claim 12, wherein during the noise sensing period, the supply sequence of the driving voltages and the reference voltages is determined according to a search sequence recorded in a lookup table.

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