TWI771040B - Active stylus receiving circuit and touch panel system using active stylus pen - Google Patents

Abstract

An active stylus pen receiving circuit receives a vector data signal sent by an active stylus pen. The vector data signal carries vector data. The vector data includes in-phase data and quadrature data. The active stylus pen receiving circuit includes: a delta-sigma analog-to-digital converter for performing delta-sigma operation to convert the vector data signal into a 1-bit bit-stream; and a first logic gate circuit and a second logic gate circuit. With the first logic gate circuit, the 1-bit bit-stream and in-phase modulation carrier signal are subject to logic AND quadrature operation to generate demodulated in-phase data and, with the second logic gate circuit, the 1-bit bit-stream and quadrature modulation carrier signal are subject to logic AND quadrature operation to generate demodulated quadrature data, thereby obtaining demodulated vector data.

Description

Active pen receiving circuit and touch panel system using active pen

The present invention relates to the technical field of active pens, in particular to an active pen receiving circuit and a touch panel system using the active pen.

Active stylus has been widely used in combination with electronic devices with touch panels to provide input effects, wherein the active stylus has a transmitting circuit inside which can emit modulated vector data signals to The coordinates received by the touch panel to detect the active pen. In order to correctly receive and demodulate the vector data signal sent by the active pen, most sensors are arranged on the touch panel to sense the vector data signal, and the corresponding receiving circuit receives the vector data signal for decoding. Modulation to obtain vector data.

In the process of modulating, transmitting, receiving and demodulating the vector data, the active pen modulates the vector data, for example, with a carrier wave, wherein the vector data includes in-phase data and quadrature data, and the modulated vector data The signal is sent by the active pen to be received by the corresponding receiving circuit. The receiving circuit converts the received vector data signal with a successive-approximation register analog-to-digital converter (SAR ADC). Convert it into an N-bit digital signal (for example, N is 10), and then use two multipliers to demodulate the N-bit digital signal with an in-phase carrier and a quadrature carrier respectively, so as to demodulate the in-phase signal. data and orthogonal data to obtain the original vector data.

However, in the aforementioned structure of the touch panel using the active pen, the touch panel needs to have a large number of sensors to correctly sense the vector data signal sent by the active pen. Therefore, the number of corresponding receiving circuits is also extremely large. Each receiving circuit needs to use an analog-to-digital converter and two multipliers, resulting in the need to use a large number of analog-to-digital converters and multipliers. The data rate of the converter determines the sampling rate of the signal sent by the active pen. Under the consideration of circuit area and power consumption, the data rate of using a progressive analog digital converter is generally 1.6MHz. Therefore, it is not easy to Increase the sampling rate of the signal and affect the quality of the signal reception.

Therefore, there are still many deficiencies in the design of the conventional active pen receiving circuit, and it is necessary to improve it.

The main purpose of the present invention is to provide an active pen receiving circuit and a touch panel system using an active pen. By using the sigma-delta analog-to-digital converter and logic sum gates to demodulate and transform vector data, not only can the signal be effectively improved The receiving quality is improved, and the hardware cost and circuit area can be greatly reduced because the hardware multiplier is not required, thereby effectively reducing the power consumption.

According to a feature of the present invention, an active pen receiving circuit is provided. The active pen receiving circuit receives a vector data signal sent by an active pen. The vector data signal carries vector data, and the vector data includes in-phase data and quadrature data. The pen receiving circuit includes: a sigma-delta analog-to-digital converter, which converts the vector data signal into a 1-bit bit stream through sigma-delta operation; and a first logic gate circuit and a second logic gate circuit, the first logic gate The circuit performs logic and quadrature operations on the 1-bit bit stream and the in-phase modulated carrier signal to generate demodulated in-phase data. The second logic gate circuit converts the 1-bit bit stream and quadrature modulation. The carrier signal performs logic and quadrature operations to generate demodulated quadrature data, thereby obtaining demodulated vector data.

According to another feature of the present invention, a touch panel system is provided. The touch panel system includes: an active pen that sends out a vector data signal carrying vector data, wherein the vector data includes in-phase data and quadrature data; a touch The panel has a plurality of sensors to sense the vector data signal sent by the active pen; and a receiving device has a plurality of active pen receiving circuits, each active pen receiving circuit is connected to at least one sensor, and includes: an integral delta The analog-to-digital converter converts the vector data signal into a 1-bit bit stream by integral triangular operation; and a first logic gate circuit and a second logic gate circuit, the first logic gate circuit converts the 1-bit bits The stream and the in-phase modulated carrier signal perform logical and quadrature operations to generate demodulated in-phase data. The second logic gate circuit performs logical and quadrature operations on the 1-bit bit stream and the quadrature modulated carrier signal. , and generate the demodulated and transformed quadrature data, so as to obtain the demodulated and transformed vector data.

The above overview and the following detailed description are exemplary in nature, and are intended to further illustrate the scope of the present invention, and other objects and advantages of the present invention will be explained in the following descriptions and drawings.

In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the embodiments of the present invention, and are not used to limit the present invention.

1 shows a touch panel system using an active pen according to the present invention, which includes an active pen 10, a touch panel 20, and a receiving device 30, wherein the receiving device 30 is disposed in an integrated circuit ( IC) 60, and the integrated circuit 60 further has a plurality of multiplexers (multiplexers) 40 and a microcontroller (MCU) 50. The active pen 10 has a tip 11 and a ring 13 that can emit vector data signals, and the touch panel 20 has a plurality of sensors Sx arranged in a matrix, which can sense the tip 11 or the ring of the active pen 10 13. The receiving device 30 has a plurality of active pen receiving circuits 31 to receive the vector data signal for processing to obtain the vector data X(t).

FIG. 2 is a schematic diagram of the vector data signal emitted by the active pen 10. As shown in the figure, the active pen 10 modulates the vector data X(t) with the carrier signal cos(2πωt)+sin(2πωt), for example. , so that the vector data signal carries the vector data X(t), wherein the vector data X(t) includes the in-phase data Xi(t) and the quadrature data Xq(t), and the modulated vector data signal Xi(t) cos(2πωt)+Xq(t) sin(2πωt) is emitted by the pen tip 11 or the pen ring 13 of the active pen 10 .

Please refer to FIG. 1 and FIG. 2 together, the sensor Sx of the touch panel 20 can sense the vector data signal Xi(t)cos(2πωt)+Xq(t) emitted by the pen tip 11 or the pen ring 13 of the active pen 10 sin(2πωt), and received by the corresponding active pen receiving circuit 31 of the receiving device 30, each sensor Sx can correspond to an active pen receiving circuit 31, but in fact, in order to reduce the number of required active pen receiving circuits 31, each sensor Sx An active pen receiving circuit 31 is connected to at least one sensor Sx, for example, N sensors Sx can be connected to an active pen receiving circuit 31 through an N-to-1 multiplexer 40, wherein N is an integer greater than 1 , so that an active pen receiving circuit 31 can receive the vector data signals Xi(t)cos(2πωt)+Xq(t)sin(2πωt) induced by the N sensors Sx in a multiplexed manner, that is, by The multiplexer 40 is set so that the N sensors Sx correspond to an active pen receiving circuit 31 , and N=4 is shown in FIG. 1 , but this is only an example and is not intended to limit the present invention.

FIG. 3 is a schematic diagram of the aforementioned active pen receiving circuit 31 . As shown in the figure, each active pen receiving circuit 31 has a delta-sigma ADC 311 , a first logic gate circuit 312 and a second logic gate circuit 312 . The logic gate circuit 313, wherein the sigma-delta analog-to-digital converter 311 is used to convert the received vector data signal Xi(t)cos(2πωt)+Xq(t)sin(2πωt) into 1-bit bits by sigma-delta operation The digital signal of the bit stream, the 1-bit bit stream is then subjected to logic and quadrature operations with the in-phase modulated carrier signal cos(2πωt) through the first logic gate circuit 312 to achieve the effect of demodulation, and demodulation is generated. The transformed in-phase data Xi(t), and the 1-bit bit stream is also subjected to logic and quadrature operations with the quadrature modulation carrier signal sin(2πωt) through the second logic gate circuit 313 to achieve the effect of demodulation , and the demodulated quadrature data Xq(t) is generated, and the demodulated vector data X(t) is obtained accordingly, and sent to the microcontroller 50 as shown in FIG. 1 for touch input, The touch coordinates are obtained after calculation. 3 shows that the first logic gate circuit 312 has a plurality of first equivalent logic and units 321, each of which has a first input terminal a connected to a 1-bit bit stream, A second input terminal b is connected to a corresponding bit in the in-phase modulated carrier signal cos(2πωt) and an output terminal c for outputting the in-phase data Xi(t); the second logic gate circuit 313 has a plurality of second Equivalent logical sum unit 322, each second equivalent logical sum unit 322 has a first input terminal a connected to the 1-bit bit stream, and a second input terminal b connected to the quadrature modulation carrier signal sin A corresponding bit in (2πωt) and an output terminal c are used to output the quadrature data Xq(t), wherein the equivalent logic of each logic gate circuit 312, 313 and the number of units 321, 322 are adjusted by in-phase modulation It is determined by the accuracy of the variable carrier signal cos(2πωt) and the quadrature modulation carrier signal sin(2πωt), that is, when the in-phase modulation carrier signal cos(2πωt) or the quadrature modulation carrier signal sin(2πωt) has At the M-bit precision, each logic gate circuit 312, 313 has M equivalent logic sum units 321, 322, accordingly, each of the M equivalent logic sum units 321, 322 has an input terminal a of the equivalent logic sum unit 321, 322 The 1-bit bit stream output by the sigma-delta-analog digital converter 311 is connected, and the other input terminal b is connected to the M bits of the in-phase modulation carrier signal cos(2πωt) or the quadrature modulation carrier signal sin(2πωt). 1 bit, so that the output terminals c of the M equivalent logic sum units 321, 322 of a logic gate circuit 312, 313 can output the in-phase data Xi(t) or the quadrature data Xq(t).

FIG. 4 is a circuit diagram of an embodiment of an active pen receiving circuit. In this embodiment, the aforementioned equivalent logic and units 321 and 322 are implemented by logic AND gates. As shown in the figure, the first equivalent logic and unit 321 or the second equivalent logic and unit 321 is a logic and gate, wherein the logic AND gate has two input terminals as the first input terminal a and the second input terminal b of the first equivalent logic sum unit 321 or the second equivalent logic sum unit 322 respectively, and an output terminal as the first input terminal a and the second input terminal b of the second equivalent logic sum unit 322 An output terminal c of an equivalent logic sum unit 321 or a second equivalent logic sum unit 322 .

FIG. 5 is a circuit diagram of another embodiment of an active pen receiving circuit. In this embodiment, the aforementioned equivalent logic and units 321 and 322 are implemented by a 2-to-1 multiplexer. As shown in the figure, the first equivalent logic and unit 321 or the second equivalent logic and unit 322 are A 2-to-1 multiplexer, wherein the 2-to-1 multiplexer has a selection terminal as the first input terminal a of the first equivalent logic sum unit 321 or the second equivalent logic sum unit 322, and the two input terminals are respectively used as the first input terminal a of the equivalent logic sum unit 321 or the second equivalent logic sum unit 322. The second input terminal b of an equivalent logic sum unit 321 or the second equivalent logic sum unit 322 and the input logic 0, and an output terminal are used as the first equivalent logic sum unit 321 or the second equivalent logic sum unit 322. output c.

FIG. 6 is a circuit diagram of still another embodiment of an active pen receiving circuit. In this embodiment, the aforementioned equivalent logic and units 321, 322 are implemented by logical OR gates and logical inversion gates (NOT gate), as shown in the figure, the first equivalent logic and units 321 or the second, etc. The effective logic AND unit 322 is composed of a logical OR gate and three logical inversion gates, wherein the logical OR gate has two input terminals respectively connected to a logic inversion gate as the first equivalent logic sum unit 321 or the second equivalent logic The first input terminal a, the second input terminal b, and an output terminal of the logic sum unit 322 are connected to a logic inversion gate as the output end c of the first equivalent logic sum unit 321 or the second equivalent logic sum unit 322 .

Accordingly, the present invention can realize the logic gate circuits 312 and 313 with simple combinational logic elements, so as to achieve the effect of signal demodulation without using a complex multiplier circuit. In addition, in addition to using the aforementioned logic AND gates, 2-to-1 multiplexers, logic OR gates, and logic inversion gates, the aforementioned equivalent logic sum units 321 and 322 can also be implemented by other combinational logic elements, such as using a logic inversion and gate ( NAND gate) has an output terminal connected to a logic inversion gate, or a logic inversion NOR gate (NOR gate) with two input terminals connected to the two logic inversion gates respectively.

The aforesaid sigma-delta analog-to-digital converter 311 is an oversampling rate analog-to-digital converter that utilizes noise shaping and oversampling techniques to achieve a sufficient signal-to-noise ratio, SNR), its second-order input (In)/output (out) relationship can be expressed as: out(z)=In(z)+Q(z)×(1−Z ^-1 ) ² , out(z)=In (z)*SFT+Q(z)*NFT, where z/Z stands for z domain transform, STF stands for signal transfer function, Q(z) stands for z domain quantization (z domain transform) quantization) noise, NTF stands for noise transfer function (noise transfer function), when the input signal enters the integral triangle modulation and after oversampling and noise frequency shifting, it is no longer through digital filtering and downscaling (Decimation), directly through the positive The in-phase data (Xi_rx) and the quadrature data (Xq_rx) are obtained by intermodulation, and the noise is filtered out by the quadrature modulation after frequency shifting, which can achieve the function of an analog-to-digital converter. Therefore, the above-mentioned active pen receiving circuit The signal processing performed by 31 can be expressed as: ADC _IN = Xi×cos(2πωt)+Xq×sin(2πωt), ADC _OUT = ADC _IN *SFT+Qn*NFT, Xi_rx = Xi+Qn×NFT×cos(2πωt ), Xq_rx = Xq+Qn×NFT×sin(2πωt), where ADC _IN represents the input of the sigma-delta analog to digital converter 311 , ADC _OUT represents the output of the sigma-delta analog to the digital converter 311 , Xi represents the active pen 10 The transmitted in-phase data, Xq represents the quadrature data transmitted by the active pen 10, cos(2πωt) represents the in-phase modulated carrier signal, sin(2πωt) represents the quadrature modulated carrier signal, and Xi_rx represents the The output data of the active pen receiving circuit 31 (demodulated in-phase data), Xq_rx represents the output data of the active pen receiving circuit 31 (the demodulated quadrature data), STF represents the signal transition function, and Qn represents the time domain quantization (time domain quantization) Noise, NTF stands for Noise Transfer Function.

In the above-mentioned active pen receiving circuit 31, the data rate of the sigma-delta analog to digital converter 311 can reach 10MHz or more, so it has a very high signal sampling rate, which can effectively improve the quality of signal reception. The digital signal output by the analog-to-digital converter 311 is a 1-bit bit stream, so the logic gate circuits 312, 313 are used to modulate the 1-bit bit stream and the in-phase modulation carrier signal cos(2πωt) or the quadrature modulation carrier signal Sin(2πωt) can achieve the effect of demodulation by performing logic and quadrature operations. Not only is the operation simple, but no hardware multiplier is required. Therefore, the hardware cost and circuit area can be greatly reduced, thereby effectively reducing power consumption.

The above-mentioned embodiments are only examples for convenience of description, and the scope of the claims claimed in the present invention should be based on the scope of the patent application, rather than being limited to the above-mentioned embodiments.

10: Active Pen 11: Nib 13: pen ring 20: Touch panel 30: Receiver 31: Active pen receiving circuit Sx: Sensor 40: Multiplexer 50: Microcontroller 60: Integrated Circuits 311: Integral-Delta-Analog-to-Digital Converter 312, 313: Logic Gate Circuits 321, 322: Equivalent Logic and Units a,b: input terminal c: output terminal

FIG. 1 shows a touch panel system using an active pen according to the present invention. FIG. 2 shows a schematic diagram of the active pen emitting vector data signals. FIG. 3 is a schematic diagram of an active pen receiving circuit. FIG. 4 is a circuit diagram of an embodiment of an active pen receiving circuit. FIG. 5 is a circuit diagram of another embodiment of an active pen receiving circuit. FIG. 6 is a circuit diagram of still another embodiment of an active pen receiving circuit.

311: Integral-Delta-Analog-to-Digital Converter

312, 313: Logic Gate Circuits

321, 322: Equivalent Logic and Units

a,b: input terminal

c: output terminal

Claims (18)

An active pen receiving circuit receives a vector data signal sent by an active pen, the vector data signal carries vector data, the vector data includes in-phase data and quadrature data, and the active pen receiving circuit includes: a sigma-delta analog-to-digital converter that converts the vector data signal into a 1-bit bit stream using sigma-delta operations; and a first logic gate circuit and a second logic gate circuit, the first logic gate circuit performs logic and quadrature operations on the 1-bit bit stream and the in-phase modulated carrier signal to generate the demodulated In-phase data, the second logic gate circuit performs logic and quadrature operations on the 1-bit bit stream and the quadrature modulation carrier signal to generate the demodulated quadrature data, so as to obtain the demodulation modulation After the vector data. The active pen receiving circuit of claim 1, wherein the vector data signal is: Xi(t)cos(2πωt)+Xq(t)sin(2πωt), wherein Xi(t) represents in-phase data, Xq( t) represents the quadrature data, cos(2πωt) represents the in-phase modulated carrier signal, and sin(2πωt) represents the quadrature modulated carrier signal. The active pen receiving circuit of claim 1, wherein the data rate of the sigma-delta analog-to-digital converter is greater than or equal to 10MHz. The active pen receiving circuit of claim 1, wherein the sigma-delta analog-to-digital converter has a second-order input/output relationship: out(z)=In(z)+Q(z)×(1−Z ^-1 ) ² ; and out(z)=In(z)*SFT+Q(z)*NFT, where z/Z represents z-domain transformation, STF represents signal transition function, and Q(z) represents z-domain quantization noise information, NTF stands for Noise Transfer Function. The active pen receiving circuit of claim 1, wherein the first logic gate circuit has a plurality of first equivalent logic and units, and each first equivalent logic and unit has a first input terminal connected to the 1 A bit stream of bits, a second input terminal connected to a corresponding bit in the in-phase modulated carrier signal, and an output terminal for outputting the in-phase data; the second logic gate circuit has a plurality of second, etc. Effective logic and unit, each second equivalent logic and unit has a first input connected to the 1-bit bit stream, and a second input connected to a corresponding bit in the quadrature modulated carrier signal element, and an output terminal for outputting the orthogonal data. The active pen receiving circuit of claim 5, wherein the first equivalent logic sum unit or the second equivalent logic sum unit is a logic sum gate having two input terminals as the first equivalent logic sum unit or The first input terminal and the second input terminal of the second equivalent logic sum unit, and an output terminal are used as the output end of the first equivalent logic sum unit or the second equivalent logic sum unit. The active pen receiving circuit of claim 5, wherein the first equivalent logic sum unit or the second equivalent logic sum unit is a 2-to-1 multiplexer, and the 2-to-1 multiplexer has a selection terminal as a The first input terminal and the two input terminals of the first equivalent logic sum unit or the second equivalent logic sum unit are respectively used as the second input terminal and input of the first equivalent logic sum unit or the second equivalent logic sum unit A logic 0 and an output terminal are used as the output terminal of the first equivalent logic sum unit or the second equivalent logic sum unit. The active pen receiving circuit as claimed in claim 5, wherein the first equivalent logic sum unit or the second equivalent logic sum unit is a logic OR gate with two input ends respectively connected to a logic inversion gate as the first The first input terminal and the second input terminal of the equivalent logic sum unit or the second equivalent logic sum unit, and an output terminal are connected with a logic inversion gate as the first equivalent logic sum unit or the second equivalent logic sum unit output of the unit. A touch panel system, comprising: an active pen that emits a vector data signal carrying vector data, wherein the vector data includes in-phase data and quadrature data; a touch panel with a plurality of sensors for sensing the vector data signal sent by the active pen; and A receiving device has a plurality of active pen receiving circuits, each active pen receiving circuit is connected to at least one sensor, and includes: a sigma-delta analog-to-digital converter that converts the vector data signal into a 1-bit bit stream using sigma-delta operations; and a first logic gate circuit and a second logic gate circuit, the first logic gate circuit performs logic and quadrature operations on the 1-bit bit stream and the in-phase modulated carrier signal to generate the demodulated In-phase data, the second logic gate circuit performs logic and quadrature operations on the 1-bit bit stream and the quadrature modulation carrier signal to generate the demodulated quadrature data, so as to obtain the demodulation modulation After the vector data. The touch panel system of claim 9, wherein the active pen modulates vector data with a carrier signal to generate the vector data signal: Xi(t)cos(2πωt)+Xq(t)sin(2πωt ), where Xi(t) represents the in-phase data, Xq(t) represents the quadrature data, cos(2πωt) represents the in-phase modulated carrier signal, and sin(2πωt) represents the quadrature modulated carrier signal. The touch panel system of claim 9, wherein N sensors in the plurality of sensors in the touch panel are connected to an active pen receiving circuit through an N-to-1 multiplexer, wherein N is greater than 1 the integer. The touch panel system according to claim 9, wherein the vector data signal is: Xi(t)cos(2πωt)+Xq(t)sin(2πωt), wherein Xi(t) represents in-phase data, Xq( t) represents the quadrature data, cos(2πωt) represents the in-phase modulated carrier signal, and sin(2πωt) represents the quadrature modulated carrier signal. The touch panel system of claim 9, wherein the data rate of the sigma-delta analog-to-digital converter is greater than or equal to 10 MHz. The touch panel system of claim 9, wherein the sigma-delta analog-to-digital converter has a second-order input/output relationship: out(z)=In(z)+Q(z)×(1−Z ^-1 ) ² , out(z)=In(z)*SFT+Q(z)*NFT, where z/Z stands for z-domain transform, STF stands for signal transition function, and Q(z) stands for z-domain quantization noise , NTF stands for Noise Transfer Function. The touch panel system of claim 9, wherein the first logic gate circuit has a plurality of first equivalent logic and units, and each first equivalent logic and unit has a first input terminal connected to the 1 A bit stream of bits, a second input terminal connected to a corresponding bit in the in-phase modulated carrier signal, and an output terminal for outputting the in-phase data; the second logic gate circuit has a plurality of second, etc. Effective logic and unit, each second equivalent logic and unit has a first input connected to the 1-bit bit stream, and a second input connected to a corresponding bit in the quadrature modulated carrier signal element, and an output terminal for outputting the orthogonal data. The touch panel system of claim 15, wherein the first equivalent logic and unit or the second equivalent logic and unit is a logic and gate having two input terminals as the first equivalent logic and unit or The first input terminal and the second input terminal of the second equivalent logic sum unit, and an output terminal are used as the output end of the first equivalent logic sum unit or the second equivalent logic sum unit. The touch panel system of claim 15, wherein the first equivalent logic sum unit or the second equivalent logic sum unit is a 2-to-1 multiplexer, and the 2-to-1 multiplexer has a selection terminal as a The first input terminal and the two input terminals of the first equivalent logic sum unit or the second equivalent logic sum unit are respectively used as the second input terminal and input of the first equivalent logic sum unit or the second equivalent logic sum unit A logic 0 and an output terminal are used as the output terminal of the first equivalent logic sum unit or the second equivalent logic sum unit. The touch panel system according to claim 15, wherein the first equivalent logic sum unit or the second equivalent logic sum unit is a logic OR gate having two input ends respectively connected to a logic inversion gate as the first The first input terminal and the second input terminal of the equivalent logic sum unit or the second equivalent logic sum unit, and an output terminal are connected with a logic inversion gate as the first equivalent logic sum unit or the second equivalent logic sum unit output of the unit.

Images