Stylus control system and stylus control method using same

Abstract

A better embodiment of the present invention relates to a stylus control system and a stylus control method using the same for controlling a display device according to an operation of a stylus, the stylus control method comprising: dividing the operation of the display device into an uplink transmission time, a downlink reception time, and a touch time; when the display equipment is in the downlink receiving time, receiving a signal by a plurality of receivers of the display equipment, and performing demodulation; when digital data obtained after demodulation of the received signal reaches a threshold value, phase comparison is carried out; and when the difference between the phase of the digital data and a preset phase is greater than a phase boundary value, abandoning the digital data.

Description

Technical Field

[0001] The present invention relates to a technology of an input device controlled by a stylus pen, and in particular to a stylus pen control system and a stylus pen control method using the same. Background Art

[0002] With the increasing popularity of digital drawing, electronic note-taking, and smart devices, stylus technology has become an important input tool. These styluses typically include pressure sensing, tilt angle detection, and precise positioning capabilities, enabling a more refined operating experience on touch screens. The principle is usually to detect the interaction between the stylus and the screen through electronic sensing technology. Common stylus technologies are capacitive and electromagnetic. Capacitive styluses use changes in the electric field of the touch screen to identify the position of the pen stroke and change the thickness of the pen stroke through pressure sensing; electromagnetic styluses use a built-in electromagnetic field to interact with the induction coil in the touch screen to determine the position and provide more precise handwriting control. With the continuous advancement of technology, modern styluses have also added high-resolution dynamic sensing, which can provide a close-to-real handwriting experience.

[0003] However, styluses often encounter common-mode interference (common noise) during operation, significantly challenging the accuracy of signal demodulation. Common-mode noise often significantly impacts accuracy during stylus operation, particularly during signal demodulation. First, when an external power supply is plugged in, high-frequency noise transmitted by the power supply can enter the stylus system or touch panel through the power cord, becoming a major source of common-mode interference. This noise signal originates from unstable power supplies or device operation. In plug-in devices, particularly, unstable or momentary current fluctuations can generate strong electromagnetic interference. This external interference signal can propagate through the touch panel's circuitry and the stylus's sensing system, affecting the stylus's precise positioning and pressure sensing. This can prevent the stylus from accurately responding to user input, leading to false touches or delays.

[0004] Furthermore, when the touch panel transmits an uplink signal to the stylus, if the user's left hand touches the panel and their right hand touches the panel's ground terminal, this contact pattern causes the human body to become a conductive medium for electromagnetic signals. In this case, the uplink signal simultaneously enters the stylus's receiving and ground terminals, causing common-mode noise. Specifically, the signal not only travels from the touch panel to the stylus's receiving terminal but also travels through the human body to the ground terminal, forming a common-mode signal between the stylus's receiving and ground terminals. In this situation, the stylus receives interference signals from different paths simultaneously, making it impossible to correctly distinguish valid operational signals from external interference during signal demodulation, further impacting the stability and accuracy of handwriting. In this environment, the stylus's user experience can be significantly affected, especially in precision operations. Therefore, a control method is needed to improve and eliminate the effects of common-mode noise on the stylus. Summary of the Invention

[0005] Embodiments of the present invention provide a stylus control system and a stylus control method using the same, to prevent common mode noise from affecting position sensing errors of the stylus and to improve its sensing accuracy.

[0006] An embodiment of the present invention provides a stylus control method for controlling a display device based on the operation of a stylus. The stylus control method includes: dividing the operation of the display device into an uplink transmission time, a downlink reception time, and a touch time; when the display device is in the downlink reception time, multiple receivers of the display device receive a signal and perform demodulation; when the digital data of the demodulated received signal reaches a threshold, a phase comparison is performed; and when the phase difference between the digital data and a preset phase is greater than a phase boundary value, the digital data is discarded.

[0007] Another embodiment of the present invention provides a stylus control system comprising a stylus and a display device. The display device's operation is divided into an uplink transmission period, a downlink reception period, and a touch period. During the downlink reception period, the display device receives a signal through its multiple receivers and performs demodulation. When the demodulated digital data of the received signal reaches a threshold, a phase comparison is performed. If the phase difference between the digital data and a predetermined phase exceeds a phase threshold, the digital data is discarded.

[0008] The stylus control system and the stylus control method using the same according to the preferred embodiment of the present invention further include: recording the number of consecutive times that the phase of the digital data differs from the preset phase by more than the phase boundary value; and when the number of consecutive times is greater than the preset number, during the uplink transmission time of the display device, notifying the stylus to change the frequency of the downlink transmission through an uplink transmission signal.

[0009] According to a preferred embodiment of the present invention, a stylus control system and a stylus control method using the same are described. When the demodulated digital data of the received signal reaches the threshold, a phase comparison is performed, including: extracting the phase of the digital data to obtain a first phase; extracting the phase of the previous digital data to obtain a second phase; comparing the first phase and the second phase to obtain a phase difference; and determining whether the phase difference is greater than a preset phase difference.

[0010] According to a preferred embodiment of the present invention, a stylus control system and a stylus control method using the same are described. When the demodulated digital data of the received signal reaches the threshold, a phase comparison is performed, including: extracting the phase of the digital data to obtain a first phase; extracting the phase of the synchronization signal of the digital data to obtain a second phase; comparing the first phase and the second phase to obtain a phase difference; and determining whether the phase difference is greater than a preset phase difference.

[0011] In summary, the embodiments of the present invention adopt a method in which multiple receivers receive signals and perform demodulation within the downlink receiving time. Furthermore, the present invention compares the difference between the phase of the demodulated digital data and the default phase, and discards the data if the phase boundary value is exceeded, thereby effectively avoiding sensing errors caused by common mode noise or other interference factors. In addition, the system can record the number of consecutive times when the phase difference is too large, and when the preset number threshold is reached, it automatically notifies the stylus to adjust the downlink transmission frequency through the uplink transmission signal to dynamically adapt to environmental changes and further improve touch accuracy and stability. Through the above-mentioned technical means, the present invention can significantly reduce the accuracy problem of the stylus caused by signal interference, and improve the reliability of the overall system and user experience.

[0012] To further understand the technology, means and effects of the present invention, reference may be made to the following detailed description and accompanying drawings, which may provide a thorough and specific understanding of the purposes, features and concepts of the present invention. However, the following detailed description and accompanying drawings are intended only to provide a reference and illustration of the implementation of the present invention and are not intended to limit the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The accompanying drawings are provided to help those skilled in the art to which the present invention pertains to further understanding of the present invention and are incorporated into and constitute a part of the specification of the present invention. The accompanying drawings illustrate exemplary embodiments of the present invention and, together with the specification of the present invention, are used to explain the principles of the present invention.

[0014] Figure 1 FIG. 1 is a schematic diagram of a stylus control system according to a preferred embodiment of the present invention.

[0015] Figure 2 FIG. 1 is a circuit block diagram of a transmission module of a stylus pen 101 in a stylus pen control system according to a preferred embodiment of the present invention.

[0016] Figure 3 FIG. 1 is a circuit block diagram of a receiving module of the touch panel 103 of the stylus control system according to a preferred embodiment of the present invention.

[0017] Figure 4 FIG. 4 is a flow chart of a stylus control method according to a preferred embodiment of the present invention.

[0018] Figure 5 FIG. 4 is a flow chart of a stylus control method according to a preferred embodiment of the present invention.

[0019] Explanation of symbols:

[0020] 101: Stylus

[0021] 102: Smart mobile devices

[0022] 103: Touch panel

[0023] 201: IQ modulation circuit

[0024] 202: First analog multiplier

[0025] 203: Second analog multiplier

[0026] 204: Signal mixing circuit

[0027] 205: Transmitting antenna

[0028] XI: In-phase signal

[0029] XQ: Quadrature signal

[0030] 301: Analog front-end receiving circuit

[0031] 302: Digital decoding circuit

[0032] 321: In-phase component acquisition circuit

[0033] 322: Quadrature component acquisition circuit

[0034] CA: Control Amplifier

[0035] ADC: Analog-to-Digital Converter

[0036] 323: First digital multiplier

[0037] 325: Second digital multiplier

[0038] 324: First digital signal processing circuit

[0039] 326: Second digital signal processing circuit

[0040] 350: Stylus control circuit

[0041] S401-S415, S501-S503: Process steps of a stylus control method according to a preferred embodiment of the present invention DETAILED DESCRIPTION

[0042] Reference will now be made in detail to exemplary embodiments of the present invention, which are illustrated in the accompanying drawings. Wherever possible, the same reference numerals will be used in the drawings and the description to refer to the same or similar parts. The exemplary embodiments are merely one way to implement the design concepts of the present invention, and the following examples are not intended to limit the present invention.

[0043] Figure 1 This is a schematic diagram of a stylus control system according to a preferred embodiment of the present invention. Figure 1 , this stylus control system takes a mobile device with a stylus as an example, and this stylus control system includes a stylus 101 and a smart mobile device 102. In this embodiment, the smart mobile device 102 is, for example, a smart phone, a tablet computer, or a laptop computer with a stylus, but the present invention is not limited thereto. The smart mobile device 102 includes a touch panel 103. The touch panel 103 of the smart mobile device 102 operates in a time-division multiplexing (TDM) manner. Its operating mode includes a touch time and a stylus operating time. During the touch time, the touch panel 103 performs capacitance detection on the finger or its equivalent conductor.

[0044] The stylus operation time of the touch panel 103 includes an uplink transmission time and a downlink reception time. During the uplink transmission time, the touch panel 103 generally transmits data to the stylus 101. Generally, this uplink transmission time is used to transmit signals such as clock and synchronization signals, system configuration / commands, charging control signals, or security verification. During the downlink transmission time, the touch panel 103 functions as a receiver, receiving signals sent back by the stylus 101.

[0045] Figure 2 This is a circuit block diagram of the transmission module of the stylus pen 101 of the stylus pen control system according to a preferred embodiment of the present invention. Figure 2 In this embodiment, the transmission module circuit of the stylus 101 includes an IQ modulation circuit 201, a first analog multiplier 202, a second analog multiplier 203, a signal mixing circuit 204, and a transmitting antenna 205. The IQ modulation circuit 201 is used to convert the transmitted data into an in-phase signal XI and a quadrature signal XQ. The first analog multiplier 202 is used to multiply the in-phase signal XI with a cosine carrier to obtain a real modulated signal. The second analog multiplier 203 is used to multiply the quadrature signal XQ with a sine carrier to obtain an imaginary modulated signal. The signal mixing circuit 204 is used to mix the real modulated signal and the imaginary modulated signal, and finally transmit the mixed signal to a receiving end, such as the receiving module of the touch panel 103, via the transmitting antenna 205.

[0046] Figure 3 This is a circuit block diagram of the receiving module of the touch panel 103 of the stylus control system according to a preferred embodiment of the present invention. Figure 3 The receiving module of the touch panel 103 includes a plurality of analog front-end receiving circuits 301 and a plurality of digital decoding circuits (digital domain) 302. The analog front-end receiving circuit 301 includes a plurality of control amplifiers CA and a plurality of analog-to-digital converters ADC. The digital decoding circuit 302 includes an in-phase component extraction circuit 321 and a quadrature component extraction circuit 322. The in-phase component extraction circuit 321 includes a first digital multiplier 323 and a first digital signal processing circuit 324, while the quadrature component extraction circuit 321 includes a second digital multiplier 325 and a second digital signal processing circuit 326.

[0047] The number of control amplifiers CA, analog-to-digital converters ADCs, in-phase component capture circuits 321, and quadrature component capture circuits 322 is determined by the resolution provided by the touch panel 103 to the stylus 101. Specifically, each control amplifier CA is used to determine whether at least one location on the touch panel 103 receives a signal from the stylus 101. The touch panel 103 can also utilize time-sharing multitasking technology, dividing the panel into, for example, eight blocks. Each receiving module on the touch panel 103 is activated at each of the eight times, and switches are used to determine the signal from the stylus 101, thereby determining the stylus's position.

[0048] The control amplifier CA is used to receive and amplify the mixed signal sent by the transmitting antenna 205 of the stylus 101. The analog-to-digital converter ADC samples the signal at the output of the control amplifier CA and converts it into a digital signal. The digital signal is multiplied by a digital cosine carrier by a first digital multiplier 323 to obtain an in-phase component and its high-frequency portion. Furthermore, the digital signal is multiplied by a digital sine carrier by a second digital multiplier 325 to obtain a quadrature component and its high-frequency portion. These components are then sent to the corresponding first and second digital signal processing circuits 324 and 326, respectively. The first and second digital signal processing circuits 324 and 326 remove the high-frequency portion through digital processing, such as low-pass filtering, to demodulate the received signal into the in-phase component and the quadrature component.

[0049] The in-phase component and quadrature phase component corresponding to each of the above positions, that is, the demodulated digital data, are sent to a stylus control circuit 350. The stylus control circuit 350 uses the numerical value (e.g., absolute value) of the demodulated digital data to determine the position of the stylus 101 and the command it transmits. Generally, if the numerical value of the demodulated digital data is greater than a threshold, it indicates that a signal from the stylus 101 has been detected at that position. However, when these in-phase and quadrature phase components are interfered with by common-mode noise, the interfered in-phase and quadrature phase components may also be greater than the threshold, resulting in an erroneous position determination.

[0050] In this embodiment, the stylus control circuit 350 first defines a phase margin. For example, assuming that the stylus 101 in this case uses quadrature phase shift keying (QPSK), the signal should theoretically be one of the four phases of 45 degrees, 135 degrees, 225 degrees, and 315 degrees. Therefore, the above-mentioned phase margin is set to 10 degrees, for example. In other words, the ranges of 35 to 55 degrees, 125 to 145 degrees, 215 to 235 degrees, and 305 to 325 degrees will be regarded as correct signals. For example, -35.1 to 34.9 degrees, 55.1 to 124.9 degrees, 145.1 to 214.9 degrees, and 235.1 to 304.9 degrees will all be regarded as common mode noise.

[0051] In addition, in order to find the phase difference, or the phase standard, two implementation methods are proposed as examples below. The first method is to use the preamble / preamble symbol (Preamble) in the signal transmitted by the stylus 101. For example, the general function of the preamble packet is to provide synchronization between the transmitting end and the receiving end. In other words, this preset preamble packet is a packet known to the receiving end. Therefore, the receiving end, which is the receiving module of the touch panel 103 in this embodiment, can use this preamble packet as a reference to determine the phase reference. The second method is to use the phase of the previous digital data transmitted by the stylus 101 as a reference. This part requires additional memory space. Since the previous digital data and the next data should not have too large a phase difference, in this embodiment, the receiving module of the touch panel 103 can also use this as a reference for determining the phase.

[0052] In the above embodiment, demodulation between the transmitter and receiver is performed using quadrature phase shift keying (QPMK) as an example. However, those skilled in the art will appreciate from the above description that the present invention is also applicable to quadrature amplitude modulation (QAM), binary phase shift keying (BPSK), frequency shift keying (FSK), differential phase shift keying (DPSK), and other digital modulation techniques, and the present invention is not limited thereto. Furthermore, to facilitate explanation of the circuit operation of this embodiment, the first and second digital signal processing circuits 324 and 326 and the stylus control circuit 350 are shown as separate circuit blocks. However, those skilled in the art will appreciate that the stylus control circuit 350 can also be integrated into the touch control circuit or employ the same control circuit, and the present invention is not limited thereto.

[0053] Figure 4 This is a flow chart of a stylus control method according to a preferred embodiment of the present invention. Figure 4 , this stylus control method includes the following steps:

[0054] Step S401: Start.

[0055] Step S402: Initialize the integrated circuit.

[0056] Step S403: Provide a time slot number.

[0057] Step S404: Determine the time slot sequence number. In this embodiment, there are three time slots, namely the touch time slot, the pen uplink time slot, and the pen downlink time slot.

[0058] Step S405: Perform pen uplink transmission, uploading the uplink data to be transmitted to the stylus to the stylus.

[0059] Step S406: Perform touch detection, such as finger / capacitive touch detection.

[0060] Step S407: Determine whether the raw touch data is greater than the touch threshold.

[0061] Step S408: Calculate touch data and its coordinates.

[0062] Step S409: reporting the touch coordinates to the host.

[0063] Step S410: Receive pen downlink transmission.

[0064] Step S411 : Determine whether the tone amplitude of the stylus channel is greater than a threshold.

[0065] Step S412: Determine whether the phase (tone amplitude) of the stylus channel is within the phase boundary. As mentioned above, the preamble packet or the previous signal can be used as a reference.

[0066] Step S413: discard the current stylus data.

[0067] Step S414: Calculate stylus data and coordinates.

[0068] Step S415: reporting the stylus data and coordinates.

[0069] Figure 5 This is a flow chart of a stylus control method according to a preferred embodiment of the present invention. Figure 5 In addition to the above steps, this stylus control method also includes the following steps:

[0070] Step S501: Continuing from step S413, record the number of times the phase of the digital data differs from the default phase by more than the phase threshold. In this embodiment, the number of consecutive discards is incremented by 1 in a variable manner, for example, by the internal software of the stylus control circuit.

[0071] Step S502: Determine whether the number of consecutive discards is greater than a preset number, for example, by using a stylus control circuit.

[0072] Step S503: When the number of consecutive discards exceeds a predetermined number, an uplink transmission signal is used during the display device's uplink transmission period to notify the stylus to change the downlink transmission frequency. Since continuous transmission failures indicate severe interference on this channel, in this embodiment, the stylus control circuit, such as an internal register, uses an uplink transmission signal during the display device's uplink transmission period to notify the stylus 101 to change the downlink transmission frequency. This allows the stylus 101 to change the channel to avoid interference.

[0073] In summary, the embodiments of the present invention adopt a method in which multiple receivers receive signals and perform demodulation within the downlink receiving time. Furthermore, the present invention compares the difference between the phase of the demodulated digital data and the default phase, and discards the data if it exceeds the phase boundary value, thereby effectively avoiding sensing errors caused by common mode noise or other interference factors. In addition, the system can record the number of consecutive discards due to excessive phase differences, and when the preset number threshold is reached, it automatically notifies the stylus through the uplink transmission signal to adjust the downlink transmission frequency, so as to dynamically adapt to environmental changes and further improve touch accuracy and stability. Through the above-mentioned technical means, the present invention can significantly reduce the accuracy problems of the stylus caused by signal interference, and improve the reliability of the overall system and user experience.

[0074] It should be understood that the examples and embodiments described herein are for illustrative purposes only and that various modifications or changes in light thereof will be suggested to those skilled in the art and are to be included within the spirit and purview of this application and the scope of the appended claims.

Claims

1. A stylus control method for controlling a display device according to the operation of a stylus, characterized in that: The stylus control method includes: The operation of the display device is divided into an uplink transmission time, a downlink reception time, and a touch time; When the display device is in the downlink receiving time, the multiple receivers of the display device receive the downlink signal and perform demodulation; When the demodulated digital data of the received downlink signal reaches a threshold, performing a phase comparison; and When the phase difference between the digital data and a preset phase is greater than a phase boundary value, the digital data is discarded.

2. The stylus control method according to claim 1, wherein: Also includes: Recording the number of consecutive discards in which the phase of the digital data differs from the preset phase by more than the phase boundary value; and When the number of consecutive discards is greater than a preset threshold, during the uplink transmission time of the display device, an uplink transmission signal is used to notify the stylus to change the frequency of downlink transmission.

3. The stylus pen control method according to claim 1, wherein: When the demodulated digital data of the received signal reaches the threshold, the phase comparison is performed, including: extracting the phase of the digital data to obtain a first phase; Extracting the phase of the previous digital data to obtain a second phase; Comparing the first phase and the second phase to obtain a phase difference; and It is determined whether the phase difference is greater than the preset phase difference.

4. The stylus control method according to claim 1, wherein: When the demodulated digital data of the received signal reaches the threshold, the phase comparison is performed, including: extracting the phase of the digital data to obtain a first phase; extracting the phase of the synchronization signal of the digital data to obtain a second phase; Comparing the first phase and the second phase to obtain a phase difference; and It is determined whether the phase difference is greater than the preset phase difference.

5. The stylus pen control method according to claim 4, wherein: The synchronization signal of the digital data is a preamble signal.

6. The stylus pen control method according to claim 1, wherein: When the display device is in the downlink receiving time, the multiple receivers of the display device receive the signal and perform the demodulation, including: Performing an analog-to-digital conversion process on the received signal of each of the receivers to obtain a plurality of digital values; and A phase shift modulation is performed on each of the digital values.

7. The stylus pen control method according to claim 6, wherein: Performing the phase key demodulation on each of the digital values ​​includes: After multiplying each of the digital values ​​by a cosine carrier, low-pass filtering is performed to obtain an in-phase component of a received signal of each of the receivers; and After multiplying each of the digital values ​​by a sinusoidal carrier, a low-pass filter is performed to obtain a rectangular component of a reception signal of each of the receivers.

8. A touch pen control system, characterized in that: include: a stylus; A display device, wherein the operation of the display device is divided into an uplink transmission time, a downlink reception time, and a touch time; When the display device is in the downlink receiving time, the multiple receivers of the display device receive the downlink signal and demodulate the downlink signal through the multiple digital decoding circuits; When the demodulated digital data of the received signal reaches a threshold, performing a phase comparison; and When the phase difference between the digital data and a preset phase is greater than a phase boundary value, the digital data is discarded.

9. The stylus control system according to claim 8, wherein: The display device includes: A plurality of analog front-end receiving circuits, each of which is configured to convert a received signal into a digital value at a predetermined time; and The digital decoding circuits are correspondingly coupled to each of the analog front-end receiving circuits for performing phase shift modulation on the corresponding received digital values.

10. The stylus control system according to claim 9, wherein: Each of the digital decoding circuits includes: an in-phase component extraction circuit for multiplying the corresponding digital value by a digital cosine carrier and then performing low-pass filtering to obtain an in-phase component of the received signal of each of the receivers; and The rectangular component extraction circuit is used for multiplying the corresponding digital value by a digital sinusoidal carrier and then performing low-pass filtering to obtain the rectangular component of the receiving signal of each of the receivers.

11. The stylus control system according to claim 9, wherein: The display device further includes: a stylus control circuit coupled to each of the digital decoding circuits, for capturing coordinate data of which a majority of decoded values ​​in each of the digital decoding circuits are greater than a threshold; When at least one first decoded value among the decoded values ​​is greater than the threshold, the stylus control circuit compares whether a phase difference between the first decoded value and the preset phase is greater than a phase boundary value.

12. The stylus control system according to claim 11, wherein: The stylus control circuit is further configured to record a number of consecutive discards in which the phase difference between the first decoded value and the preset phase is greater than the phase boundary value, wherein: When the continuous number is greater than a preset number, the stylus control circuit notifies the stylus to change the frequency of downlink transmission via an uplink transmission signal during the uplink transmission time of the display device.

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