WO2014101553A1

WO2014101553A1 - Capacitive screen touch detection system

Info

Publication number: WO2014101553A1
Application number: PCT/CN2013/085828
Authority: WO
Inventors: 石钱松; 冉锐; 庞树; 杜健康
Original assignee: 深圳市汇顶科技股份有限公司
Priority date: 2012-12-31
Filing date: 2013-10-23
Publication date: 2014-07-03
Also published as: CN103064571B; CN103064571A

Abstract

The present invention relates to the technical field of touch screens. Provided is a capacitive screen touch detection system, comprising: a drive control signal generation module, a drive circuit, a signal amplification and filter circuit, a sampling circuit, a data caching module, and a data processing module. Under the control of a control signal, the drive circuit is used to convert a part of the digital waveform data into a simulated drive signal, and to convert the other part of the digital waveform data into a simulated cancellation signal, the simulative drive signal being outputted to the drive terminal of a capacitive screen; the signal amplification and filter circuit is used to subtract the simulative cancellation signal from a simulative induction signal received from the induction terminal of the capacitive screen, and amplify and filter the obtained simulative difference signal. The present invention subtracts a uniform cancellation signal from an induction signal obtained from a capacitive screen, enabling the differentiation of the data of a touched node from the data of an untouched node to be more obvious, thus facilitating the recognition of a touch operation, and improving the sensitivity of the capacitive screen touch detection system.

Description

Capacitive screen touch detection system

Technical field

The invention belongs to the technical field of touch screens, and in particular relates to a capacitive touch screen detection system.

Background technique

Recently, capacitive touch screens have high light transmittance, wear resistance, and environmental resistance (temperature, humidity, etc.). Change, long life, and advanced complex features, such as multi-touch, are popular with the public. Capacitive touch detection is to determine the presence or absence of a touch by changing the capacitance to be measured. The capacitor is originally present in any two insulated conductors, and the person or touch object acting as the third conductor changes the original electric field, thereby changing the capacitance between the original two conductors.

With the development of capacitive screen technology, the sensitivity and accuracy of the capacitive touch detection system are put forward higher. How to accurately detect the slight touch operation on the capacitive screen has become a problem that needs to be solved currently.

technical problem

The technical problem to be solved by the present invention is to provide a capacitive touch detection system, which aims to improve the sensitivity of the capacitive touch detection system and accurately detect a slight touch operation on the capacitive screen.

Technical solution

The present invention is implemented in such a manner that a capacitive touch detection system includes:

a driving control signal generating module for outputting control signal and digital waveform data;

a driving circuit, coupled to the driving control signal generating module, for converting a part of the digital waveform data into an analog driving signal and converting the remaining part into analog cancellation according to the control of the control signal a signal, the analog driving signal is output to a driving end of the capacitive screen;

a signal amplification and filtering circuit is connected to the driving circuit, and is configured to perform a difference between the analog sensing signal received from the capacitive screen sensing end and the analog cancellation signal, and amplify the obtained analog difference signal and Filter processing

a sampling circuit, coupled to the signal amplification and filtering circuit, for converting the analog difference signal into a serial digital signal as sampling data;

a data buffering module, coupled to the sampling circuit, for converting the serial sampled data into parallel sampled data and buffering;

The data processing module is connected to the data cache module, and is configured to retrieve parallel sample data from the buffer area of the data cache module for processing, to obtain original value data of the capacitive screen.

Beneficial effect

Compared with the prior art, the present invention makes the difference between the touched node and the untouched node more obvious by uniformly subtracting a cancellation signal from the sensing signal obtained from the capacitive screen, thereby facilitating recognition of the touched operation. Improve the sensitivity of the capacitive touch detection system.

DRAWINGS

1 is a schematic structural diagram of a capacitive touch panel touch detection system provided by the present invention;

2 is a schematic structural diagram of a driving control signal generating module in the capacitive touch detection system of FIG. 1;

3 is a schematic diagram showing a correspondence relationship between waveform parameters and corresponding waveforms of the driving control signal generating module shown in FIG. 2;

4 is a schematic structural diagram of a driving circuit in the capacitive touch detection system of FIG. 1;

5 is a structural schematic diagram of a signal amplification and filtering circuit in the capacitive touch detection system of FIG. 1;

6 is a schematic structural diagram of a sampling circuit in the capacitive touch detection system of FIG. 1;

7 is a schematic structural diagram of a data buffer module in the capacitive touch detection system of FIG. 1;

FIG. 8 is a schematic structural diagram of a data processing module in the capacitive touch panel touch detection system of FIG. 1. FIG.

Embodiments of the invention

The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It is understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

As shown in FIG. 1 , the capacitive touch detection system provided by the present invention comprises a driving control signal generating module 1, a driving circuit 2, a signal amplifying and filtering circuit 3, a sampling circuit 4, a data buffering module 5 and a data processing module 6. The connection relationship and functions of the above parts are as follows: the drive control signal generation module 1 is for outputting control signals and digital waveform data, and the drive circuit 2 is connected to the drive control signal generation module 1 for controlling under the control signal A part of the digital waveform data is converted into an analog driving signal and the remaining part is converted into an analog cancellation signal, and the analog driving signal is output to the driving end of the capacitive screen. The signal amplification and filtering circuit 3 is connected to the driving circuit 2 for making a difference between the analog sensing signal received from the capacitive screen sensing end and the analog canceling signal, and amplifying and filtering the obtained analog difference signal. The sampling circuit 4 is connected to the signal amplification and filtering circuit 3 for converting the analog difference signal into a serial digital signal as sample data. The data buffer module 5 is connected to the sampling circuit 4 for converting serial sample data into parallel sample data and buffering it. The data processing module 6 is connected to the data cache module 5 for processing parallel sampled data from the buffer area of the data buffer module 5 for processing to obtain original value data of the capacitive screen.

The above detection system uniformly subtracts a cancellation signal from the sensing signal obtained from the capacitive screen, so that the difference between the touched node and the untouched node is more obvious, thereby facilitating recognition of the touched operation and improving the capacitive touch detection. The sensitivity of the system. It can detect the size of the capacitor on the capacitive screen in real time and convert it into the original value data that can reflect the small change of the capacitance, and then calculate the position of the finger touch according to the original value data through the corresponding software program.

Further, FIG. 2 shows a specific structure of the drive control signal generating module 1, which includes a configuration register 11, a control signal generator 12, a plurality of address signal generators 13, an address signal selection controller 14, and a first data selector 15. The original waveform data acquisition sub-module 18, the second data selector 16 and the first multiplier 17, wherein the original waveform data acquisition sub-module includes a raw waveform data table. The configuration register 11 stores configuration parameters for generating waveform data and control signals, such as the total length of the waveform, the frequency, the number of pulses, and the like. The control signal generator 12 is operative to generate a control signal and output it according to the configuration parameters in the configuration register 11.

A plurality of address signal generators 13 are operative to generate an address signal based on the received initial phase information and configuration parameters in the configuration register 11. The address signal selection controller 14 is used to control the selection of an address signal. The first data selector 15 has a plurality of signal input terminals, a signal output terminal, and a control terminal. The plurality of signal input terminals are respectively connected to the address signal generators 13 one by one, and the control terminal and the address signal selection controller are respectively connected. 14 is connected for outputting a corresponding address signal under the control of the address signal selection controller 14, i.e., allowing an address signal generated by the plurality of address signal generators 13 to pass.

The original waveform data acquisition sub-module is connected to the signal output end of the first data selector 15, and internally stores original waveform data corresponding to the address for extracting according to the address signal output by the first data selector. Raw waveform data corresponding to this address. The second data selector 16 also has a plurality of signal input terminals, a signal output terminal and a control terminal, wherein the plurality of signal input terminals are respectively configured to receive amplitude data corresponding to the address signal, and the control terminal and the address signal selection controller thereof 14 is connected for outputting corresponding amplitude data under the control of the address signal selection controller 14, that is, allowing a certain amplitude data to pass. The two input ends of the first multiplier 17 are respectively connected to the signal output ends of the original waveform data acquisition sub-module and the second data selector 16, for multiplying the original waveform data and the amplitude data to obtain digital waveform data, and generating The relationship between waveforms and parameters is shown in Figure 3.

Further, FIG. 4 shows a specific structure of the driving circuit 2, which includes a first group of digital-to-analog converters 21, a plurality of amplifiers 22, a plurality of inverters 23, a default signal generator 24, a driving signal selection controller 25, and more. The third data selector 26 and the second set of digital to analog converters 27, the total number of digital to analog converters in the first set of digital to analog converters 21 and the second set of digital to analog converters 27 and the address signals in FIG. The number of devices is equivalent, and the number N+1 (DAC0 to DACN) is exemplified in FIG. 4, that is, of the N+1 waveform data from the first multiplier 17, two waveform data are input to the first group of digital modes. The converter 21 is for generating a drive signal, and the other N-1 waveform data are input to the second group of digital-to-analog converters 27 for generating a cancellation signal. The first group of digital-to-analog converters 21 includes at least two digital-to-analog converters, exemplified by DAC0 and DAC1 in FIG. 3, and connected to the driving control signal generating module 1, under the action of the control signals, each digital-analog The converter converts the received digital waveform data into an analog signal. A plurality of amplifiers 22 are connected in one-to-one correspondence with the digital-to-analog converters of the first group of digital-to-analog converters 21 for amplifying the obtained analog signals, and the amplified signals are used as the forward drive signal SIN0P. A plurality of inverters 23 are further connected in one-to-one correspondence with the amplifier 22 for inverting the signal processed by the amplifier 22, and the inverted signal is used as the reverse drive signal SIN0N. In addition to this, the default signal generator 24 is used to generate a default drive signal. The forward drive signal SIN0P, the reverse drive signal SIN0N, and the default drive signal are the drive signals of the capacitive screen, but only one of the above three drive signals can be allowed to be output to a certain drive channel at a certain time. The drive signals on different drive channels may be the same or different at the same time, wherein the rules for the selection of the drive signals correspond to the decoding rules of the decoder decodes 671 and 672 in the data processing module 6 below. For example, the forward drive signal SIN0P is output to the drive channel TX0, and the drive channels TX1 to TXM do not output a drive signal (ie, a default drive signal outputting a low level), and the sample data data processing module 6 in this state can be The original value data of the intersection of the driving channel TX0 and each sensing channel is decoded, and the original value data of the entire touch screen can be obtained by analogy.

The drive signal selection controller 25 is used to control the selection of a certain drive signal. Each of the amplifiers 22 and the inverters 23 corresponds to a set of third data selectors 26 having a plurality of signal input terminals, a signal output terminal, and a control terminal, wherein the plurality of signal input terminals are respectively used for receiving the forward drive. The signal SIN0P, the reverse driving signal SIN0N, the default driving signal, and the control end thereof are connected to the driving signal selection controller 25 for outputting a corresponding driving signal to drive the capacitive screen under the control of the driving signal selection controller 25; In the third data selector of the same group, the input of each third data selector 26 is connected to the same amplifier 22, the same inverter 23, and a default signal generator 24, such as the drive channel TX0 in FIG. The third data selector 26 corresponding to TX10 is connected to the same amplifier 22 and inverter 23, and the third data selector 26 corresponding to the drive channels TX11 to TXM is connected to the same amplifier 22 and inverter 23.

The second group of digital-to-analog converters 27 includes a plurality of digital-to-analog converters, such as DAC 20 and DACN in FIG. 3, connected to the drive control signal generating module 1, and each digital-to-analog converter receives the control signals. The digital waveform data is converted to an analog cancellation signal.

Further, FIG. 5 shows a specific structure of the signal amplifying and filtering circuit 3, including a plurality of amplifying circuits 31 and a plurality of filters 32, and the amplifying circuit 31 can be selected with a programmable gain amplifier (Programmable) Gain The Amplifier (PGA) is connected to the driving circuit 2 for making a difference between the analog sensing signal received from the capacitive screen sensing end and the analog cancellation signal, and amplifying the obtained analog difference signal. The plurality of filters 32 are connected in one-to-one correspondence with the plurality of amplifying circuits 31 for filtering the analog difference signals, and specifically, the low-pass filter and the high-pass filter can be used. In Fig. 5, RX0 to RXN represent sensing channels.

Further, FIG. 6 shows a specific structure of the sampling circuit 4, including a plurality of analog-to-digital converter ADCs, and an analog-to-digital converter ADC. The number corresponds to the number of capacitive screen sensing channels, which translates the amplified and filtered analog signals into serial digital signals.

Further, FIG. 7 shows a specific structure of the data cache module 5, including a plurality of serial to parallel converters 51, a plurality of buffer areas 52, a random access memory controller 53, a random access memory 54, a plurality of buffer areas 52, and a The random access memory controller 53, a random access memory 54, collectively constitute a data buffer. First, the serial-to-parallel converter 51 converts the serial sample data into parallel sample data and stores it in the buffer area 52 (Ping can be used) In Pong Buffer, the data in the buffer area 52 is then stored in the random access memory 54 in a fixed format by the random access memory controller 53, and finally the data is transferred to the data processing module 6.

Further, FIG. 8 shows a specific structure of the data processing module 6, including a sine signal generator 61, a cosine signal generator 62, a second multiplier 63, a third multiplier 64, two

integrators

651 and 652, and two The low pass filters 661 and 662, the two

decoders

671 and 672, and the original value data calculating unit 68. A sinusoidal signal generator 61 and a cosine signal generator 62 are used to generate a sinusoidal signal and a cosine signal, respectively. The two inputs of the second multiplier 63 are connected to a sinusoidal signal generator 61 and a data buffering module 5, respectively, for multiplying the sinusoidal signal with the parallel sampled data. Similarly, the two inputs of the third multiplier 64 are coupled to a cosine signal generator 62 and a data buffer module 5, respectively, for multiplying the cosine signal with the parallel sampled data. The two

integrators

651 and 652 are respectively connected to the second multiplier 63 and the third multiplier 64, and the two low pass filters 661 and 662 are respectively connected to the two

integrators

651 and 652 in one-to-one correspondence, and the two decoders 671 And 672 are further connected in one-to-one correspondence with the two low-

pass filters

661 and 662, respectively. Finally, the original value data calculating unit 68 is connected to the two

decoders

661 and 662, respectively, for outputting the two

decoders

661 and 662. The square of the values is added and then squared to obtain the original value data.

The above is only the preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection of the present invention. Within the scope.

Claims

A capacitive touch detection system is characterized by comprising:

a driving control signal generating module for outputting control signal and digital waveform data;

a driving circuit, coupled to the driving control signal generating module, for converting a part of the digital waveform data into an analog driving signal and converting the remaining part into analog cancellation according to the control of the control signal a signal, the analog driving signal is output to a driving end of the capacitive screen;

a signal amplification and filtering circuit is connected to the driving circuit, and is configured to perform a difference between the analog sensing signal received from the capacitive screen sensing end and the analog cancellation signal, and amplify the obtained analog difference signal and Filter processing

a sampling circuit, coupled to the signal amplification and filtering circuit, for converting the analog difference signal into a serial digital signal as sampling data;

a data buffering module, coupled to the sampling circuit, for converting the serial sampled data into parallel sampled data and buffering;

The data processing module is connected to the data cache module, and is configured to retrieve parallel sample data from the buffer area of the data cache module for processing, to obtain original value data of the capacitive screen.
The capacitive touch panel detection system of claim 1 , wherein the driving control signal generating module comprises:

a configuration register internally storing configuration parameters for generating waveform data and control signals;

a control signal generator for generating a control signal according to a configuration parameter in the configuration register;

a plurality of address signal generators for generating an address signal according to the received initial phase information and configuration parameters in the configuration register;

An address signal selection controller for controlling selection of an address signal;

a first data selector having a plurality of signal input terminals, a signal output terminal, and a control terminal, wherein the plurality of signal input terminals are respectively connected to the plurality of address signal generators in one-to-one correspondence, and the control terminal and the address are respectively a signal selection controller connection for outputting a corresponding address signal under the control of the address signal selection controller;

The original waveform data acquisition sub-module is connected to the signal output end of the first data selector, and internally stores original waveform data corresponding to the address for using the address signal output by the first data selector. Retrieving original waveform data corresponding to the address;

a second data selector having a plurality of signal input ends, a signal output end, and a control end, wherein the plurality of signal input ends are respectively configured to receive amplitude data corresponding to the address signal, and the control end and the address signal are selected a controller connection for outputting corresponding amplitude data under the control of the address signal selection controller;

a first multiplier, the two input ends of which are respectively connected to the signal output ends of the original waveform data acquisition sub-module and the second data selector, for multiplying the original waveform data and the amplitude data, Get the waveform data of the number.
The capacitive touch panel touch detection system of claim 1 wherein said drive circuit comprises:

a first set of digital-to-analog converters comprising at least two digital-to-analog converters coupled to the drive control signal generating module, each digital-to-analog converter receiving a digital waveform under the control signal Data is converted to an analog signal;

a plurality of amplifiers are connected in one-to-one correspondence with the digital-to-analog converters of the first group of digital-to-analog converters for amplifying the obtained analog signals, and the amplified signals are used as forward driving signals;

a plurality of inverters connected in one-to-one correspondence with the amplifiers for negating the signals processed by the amplifiers, and the inverted signals are used as back-drive signals;

a default signal generator for generating a default drive signal;

a drive signal selection controller for controlling selection of a drive signal;

a plurality of sets of third data selectors, wherein each of said amplifiers and said inverters corresponds to a set of third data selectors having a plurality of signal inputs, a signal output, a control terminal, and a plurality of signals thereof The input ends are respectively configured to receive the forward driving signal, the reverse driving signal, and the default driving signal, and the control end thereof is connected to the driving signal selection controller for controlling under the driving signal selection controller, Outputting corresponding driving signals to drive the capacitive screen; in the third data selector of the same group, the input of each third data selector is connected to the same amplifier, the same inverter, and the default signal has been generated Device

a second set of digital-to-analog converters including a plurality of digital-to-analog converters coupled to the drive control signal generating module, each digital-to-analog converter receiving digital waveform data under the control signal Converted to an analog cancellation signal.
The capacitive touch panel detection system of claim 1 , wherein the signal amplification and filtering circuit comprises:

a plurality of amplifying circuits each connected to the driving circuit for making a difference between the analog sensing signal received from the capacitive screen sensing end and the analog canceling signal, and the obtained simulated difference value The signal is amplified;

And a plurality of filters are connected in one-to-one correspondence with the plurality of amplifying circuits for filtering the analog difference signal.
The capacitive screen touch detection system of claim 1 wherein said sampling circuit comprises a plurality of analog to digital converters.
The capacitive touch panel detection system of claim 1 , wherein the data buffer module comprises a plurality of serial to parallel converters, and a plurality of data buffers connected in one-to-one correspondence with the plurality of serial to parallel converters.
The capacitive touch panel detection system of claim 1 , wherein the data processing module comprises:

a sinusoidal signal generator for generating a sinusoidal signal;

a cosine signal generator for generating a cosine signal;

a second multiplier having two inputs coupled to the sinusoidal signal generator and the data buffer module for multiplying the sinusoidal signal by the parallel sampled data;

a third multiplier having two inputs connected to the cosine signal generator and the data buffer module, respectively, for multiplying the cosine signal by the parallel sampled data;

Two integrators respectively connecting the second multiplier and the third multiplier;

Two low-pass filters are respectively connected to the two integrators in one-to-one correspondence;

Two decoders are respectively connected to the two low-pass filters in one-to-one correspondence;

The original value data calculating unit is respectively connected to the two decoders, and is used for adding the squares of the output values of the two decoders and then opening the square to obtain the original value data.