Integrated circuit for controlling a stylus and method performed by a stylus

Abstract

The present invention provides an integrated circuit for controlling a stylus and a method performed by the stylus, which avoids the occurrence of the phenomenon of suddenly becoming unable to write in writing. The method of the present invention is a method performed by a sensor controller (20) and a stylus (S), the sensor controller (20) periodically transmitting an uplink signal (US), the stylus (S) deciding a downlink signal and a transmission / reception schedule of the uplink signal (US) based on a reception timing of the uplink signal (US) in a case where the uplink signal (US) is received, wherein the stylus (S) includes the steps of: performing a reception operation of the uplink signal (US) for a prescribed time (P1) based on the transmission / reception schedule; and in a case where the prescribed time (P1) elapses without receiving the uplink signal through the reception operation, continuing the reception operation of the uplink signal (US) for a prescribed time (P2) instead of transmitting the downlink signal based on the transmission / reception schedule.

Description

[0001] This application is a divisional application of a Chinese invention patent application. The original invention was entitled "Stylus pen, sensor controller and method performed thereon", with application number 202110433622.3 and application date April 20, 2021. Technical Field

[0002] The present invention relates to a method performed by a stylus and a sensor controller, and to a stylus and a sensor controller. Background Technology

[0003] Electronic devices corresponding to stylus-based handwriting input are known. These devices generally consist of a touch sensor disposed on the inner side of a touch surface and a sensor controller connected to the touch sensor. The sensor controller is an integrated circuit capable of bidirectional communication with the stylus via the touch sensor. It is configured to: transmit an uplink signal via the touch sensor and receive a downlink signal transmitted by the stylus based on the uplink signal via the touch sensor, thereby detecting the position of the stylus on the touch surface. The uplink signal serves to notify the stylus of the downlink signal and the timing of the uplink signal transmission and reception, and to transmit instructions for instructing the stylus to transmit data; it is transmitted by the sensor controller at a constant period.

[0004] Patent Document 1 discloses an example of a stylus that transmits downlink signals based on the timing of uplink signal reception. In this example, the stylus first operates in a discovery state, receiving uplink signals at a constant period. If an uplink signal is received as a result of this reception, the stylus transitions to an operating state where it communicates bidirectionally with a sensor controller. While in the operating state, the stylus performs downlink signal transmission and uplink signal reception according to a transmission / reception schedule determined based on the uplink signal reception timing. If no uplink signal is received according to the transmission / reception schedule, the stylus returns to the discovery state and performs uplink signal reception.

[0005] The sensor controller described in Patent Document 1 is configured to establish pairing with the stylus based on receiving a downlink signal from the stylus, and to de-pair with the stylus if no downlink signal is received from the stylus for a certain period of time. Therefore, if the stylus returns to the detected state, the sensor controller will de-pair after a certain period of time.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2016 / 129194 Summary of the Invention

[0009] The problem that the invention aims to solve

[0010] Even when the stylus is near a touch surface that should be able to receive uplink signals, uplink signal reception sometimes fails. This stops the transmission of downlink signals from the stylus, rendering the sensor controller unable to detect the stylus's position, and pairing will eventually disengage. From the user's perspective, this is precisely the phenomenon of "suddenly becoming unable to write," and therefore requires improvement.

[0011] Therefore, one of the objectives of this invention is to provide a method, stylus, and sensor controller that can prevent the phenomenon of suddenly becoming unable to write during writing.

[0012] Methods for solving problems

[0013] One aspect of the method of the present invention is a method executed by a sensor controller and a stylus. The sensor controller periodically transmits an uplink signal, and the stylus, upon receiving the uplink signal, determines the transmission and reception schedule of the downlink signal and the uplink signal based on the reception timing of the uplink signal. The method includes the following steps: the stylus performs an uplink signal reception action within a first predetermined time period based on the transmission and reception schedule; and if the uplink signal is not received through the reception action and the first predetermined time period has elapsed, the stylus replaces the transmission of the downlink signal based on the transmission and reception schedule and continues the uplink signal reception action within a second predetermined time period.

[0014] Another aspect of the invention is a method executed by a sensor controller and a stylus, wherein the sensor controller periodically transmits an uplink signal, and the stylus, upon receiving the uplink signal, determines the transmission and reception schedule of the downlink signal and the uplink signal based on the reception timing of the uplink signal. The method includes the following steps: the stylus initiates an uplink signal reception action based on the transmission and reception schedule; and if the stylus fails to receive the uplink signal during the reception action and a first predetermined time has elapsed, it transmits a frequency modulation signal regardless of the content of the unreceived uplink signal.

[0015] When the stylus of one side of the present invention receives an uplink signal from a sensor controller that periodically transmits uplink signals, it determines the transmission and reception schedule of the downlink signal and the uplink signal based on the reception timing of the uplink signal. Based on the transmission and reception schedule, the uplink signal reception action is performed within a first predetermined time. If the uplink signal is not received through the reception action and the first predetermined time has elapsed, the transmission of the downlink signal based on the transmission and reception schedule is replaced, and the uplink signal reception action continues within a second predetermined time.

[0016] In another aspect of the invention, when the stylus receives the uplink signal from a sensor controller that periodically transmits uplink signals, it determines the transmission and reception schedule of the downlink signal and the uplink signal based on the reception timing of the uplink signal. The uplink signal reception operation is started based on the transmission and reception schedule. If the uplink signal is not received through the reception operation and a first predetermined time has elapsed, the stylus transmits a frequency modulation signal regardless of the content of the unreceived uplink signal.

[0017] The sensor controller of one side of the present invention periodically transmits the uplink signal to a stylus that determines the transmission and reception schedule of the downlink signal and the uplink signal based on the uplink signal reception timing. It includes a counter representing the elapsed time since the last reception of the downlink signal, configured to de-pair with the stylus when the value of the counter exceeds a predetermined time, determine whether the content of the downlink signal received from the stylus is the content requested via the uplink signal, and reset the counter if it is determined that the content of the downlink signal received from the stylus is different from the content requested via the uplink signal.

[0018] Invention Effects

[0019] According to one aspect of the present invention, the possibility of the stylus failing to receive uplink signals can be reduced, thus avoiding the phenomenon of suddenly becoming unable to write during writing.

[0020] According to another aspect of the invention, since the stylus continues to transmit the frequency modulation signal even if the uplink signal reception fails, the sensor controller can continue to detect the stylus position. Furthermore, it allows for de-pairing without requiring pairing. Therefore, the phenomenon of suddenly becoming unable to write during writing can be avoided. Attached Figure Description

[0021] Figure 1 This is a diagram illustrating an electronic device 2 and a stylus S according to an embodiment of the present invention.

[0022] Figure 2 It is shown Figure 1 The diagram shows the internal structure of the sensor controller 20 and the touch sensor 21.

[0023] Figure 3 (a) is a mode transition diagram showing the operation mode of the stylus S, and (b) is a mode transition diagram showing the operation mode of the sensor controller 20.

[0024] Figure 4 This is a sequence diagram of the actions of the stylus S and the sensor controller 20 when the stylus S approaches the touch surface 2a.

[0025] Figure 5 This is a sequence diagram of the actions of the stylus S and the sensor controller 20 when the stylus S fails to receive the uplink signal US, even though both the stylus S and the sensor controller 20 are in operation mode.

[0026] Figure 6 This is a sequence diagram of the actions of the stylus S and the sensor controller 20 when the stylus S fails to receive the uplink signal US, even though both the stylus S and the sensor controller 20 are in operation mode.

[0027] Figure 7 This is a sequence diagram of the actions of the stylus S and the sensor controller 20 when the stylus S performs communication maintenance mode processing but ultimately fails to receive the uplink signal US.

[0028] Figure 8 This is a flowchart illustrating the processing flow of the stylus S.

[0029] Figure 9 This is a flowchart illustrating the processing flow of the stylus S.

[0030] Figure 10 This is a flowchart illustrating the processing flow of the stylus S.

[0031] Figure 11 This is a flowchart illustrating the processing flow of the stylus S.

[0032] Figure 12 This is a flowchart illustrating the processing flow of the sensor controller 20.

[0033] Figure 13 This is a flowchart illustrating the processing flow of the sensor controller 20.

[0034] Figure 14 This is a sequence diagram showing the operation of the stylus S and sensor controller 20 in a modified embodiment of this invention. Detailed Implementation

[0035] The following is a reference to the appendix. Figure 1 The embodiments of the present invention will be described in detail below.

[0036] Figure 1 This diagram illustrates an electronic device 2 and a stylus S according to an embodiment of the present invention. The electronic device 2 is, for example, a tablet computer, a device equipped with a digitizer, etc. Figure 1 As shown, the device is configured to include a sensor controller 20, a touch sensor 21, and a host processor 22. In the case where the electronic device 2 is a tablet computer, it is also configured to include a display.

[0037] The sensor controller 20 is an integrated circuit that enables bidirectional communication with the stylus S via the touch sensor 21. For more details, please refer to [link / reference needed]. Figure 2 As will be described later, the sensor controller 20 is configured to obtain the indicated position of the stylus S within the touch surface 2a through bidirectional communication with the stylus S, and to obtain the data sent by the stylus S, and to supply them sequentially to the host processor 22. Additionally, the sensor controller 20 also performs the process of obtaining the indicated position of the finger within the touch surface 2a and sequentially supplying it to the host processor 22.

[0038] The specific method of bidirectional communication between the stylus S and the sensor controller 20 is not particularly limited, but the following description will assume the use of active electrostatic discharge (ESD). Besides ESD, electromagnetic induction (EMR) can also be used, for example. Furthermore, the signal sent from the sensor controller 20 to the stylus S will be referred to as the uplink signal US, and the signal sent from the stylus S to the sensor controller 20 will be referred to as the downlink signal DS. The uplink signal US includes instructions indicating control content relative to the stylus S. The downlink signal DS includes an unmodulated carrier signal, i.e., a tone signal, and a carrier signal modulated by specified data, i.e., a data signal.

[0039] Touch sensor 21 consists of multiple sensor electrodes disposed within the touch surface 2a. For more details about touch sensor 21, please refer to [link / reference]. Figure 2 Then it will be discussed.

[0040] The host processor 22 is the central processing unit of the electronic device 2, which performs the control of various parts of the electronic device 2 and various applications by reading and executing programs stored in the built-in memory. Among the various applications executed by the host processor 22, a drawing application can be included. This drawing application is configured to, for example, have the function of generating stroke data based on data supplied from the sensor controller 20 (the pointing position of the stylus S or finger and the data sent by the stylus S), the function of generating digital ink based on the generated stroke data, and the function of rendering and displaying the generated digital ink on a display.

[0041] like Figure 1 As shown, the stylus S comprises a processing circuit 30, a battery 31, a core 32, a pen electrode 33, and a pressure sensor 34. The processing circuit 30 is a processor that performs the various processes of the stylus S described later by reading and executing a program stored in its built-in memory, and is configured to operate on power supplied from the battery 31. The core 32 is the component that forms the tip of the stylus S. The pen electrode 33 is a conductor disposed near the top of the core 32 and electrically connected to the processing circuit 30. The pressure sensor 34 is a sensor that detects a pen pressure value representing the pressure applied to the tip of the stylus S, and is connected to the rear end of the core 32. The pen pressure value detected by the pressure sensor 34 is supplied to the processing circuit 30.

[0042] The processing circuit 30 performs the following processing: receiving the uplink signal US via the pen electrode 33, and determining the transmission and reception schedule of the downlink signal DS and the uplink signal US based on its reception timing and the information within the uplink signal US. Details of this determination will be described later. Additionally, the processing circuit 30 also performs the following processing: generating the downlink signal DS according to the instructions within the uplink signal US, and transmitting it via the pen electrode 33. The downlink signal DS generated in this way is composed solely of the frequency modulation signal T, or of the frequency modulation signal T and the data signal D, depending on the instructions contained in the uplink signal US. In addition to the aforementioned pen pressure value, the data transmitted via the data signal D may also include the pen ID, etc., pre-stored in the built-in memory of the processing circuit 30.

[0043] Figure 2This diagram illustrates the internal structure of the sensor controller 20 and the touch sensor 21. As shown in the diagram, the touch sensor 21 is configured to include multiple sensor electrodes 21X and 21Y. When the touch surface 2a is formed by the display surface of a display, one of the sensor electrodes 21X and 21Y is also used as a common electrode within the display. Electronic devices 2 of this type, in which one of the sensor electrodes 21X and 21Y is used as a common electrode within the display, are, for example, referred to as "In-cell type". On the other hand, electronic devices 2 of this type, in which sensor electrodes 21X and 21Y are respectively provided as a common electrode within the display, are, for example, referred to as "Out-cell type" or "On-cell type". Hereinafter, we will continue to describe the electronic device 2 as an In-cell type, but the present invention can also be applied to Out-cell type or On-cell type electronic devices.

[0044] When the display performs pixel driving processing, the potential of the common electrode needs to be maintained at a predetermined common potential Vcom. Therefore, in the in-cell type electronic device 2, the sensor controller 20 cannot perform communication with the stylus S or detect fingers while the display is performing pixel driving processing. Thus, the sensor controller 20 is configured to perform communication with the stylus S and finger detection using the horizontal blanking interval and vertical blanking interval when pixel driving processing is not performed. Specifically, the display period of one frame is defined as one frame, and the horizontal and vertical blanking intervals contained therein are used as time slots, with communication with the stylus S and finger detection performed in each time slot.

[0045] like Figure 2 As shown, the sensor controller 20 is configured to include an MCU 50, a logic unit 51, a transmitting unit 52, 53, a receiving unit 54, a selection unit 55, and a counter 58.

[0046] The MCU 50 and logic unit 51 are control units that control the transmission and reception operations of the sensor controller 20 by controlling the transmitting units 52 and 53, the receiving unit 54, and the selection unit 55. Specifically, the MCU 50 is a microprocessor that has internal ROM and RAM and operates by executing programs stored in them. The MCU 50 also has the function of outputting a common voltage Vcom and an instruction COM. The instruction COM is equivalent to the instruction contained in the uplink signal US. On the other hand, the logic unit 51 is configured to output control signals ctrl_t, ctrl_r, sTR, selX, and selY based on the control of the MCU 50.

[0047] The COM instruction output by the MCU50 can include information about a group of information that determines the transmission and reception schedule, information indicating the allocation of time slots and frequencies relative to the stylus S, and information indicating the content of the data that the stylus S should transmit via the data signal D. Here, the information group that determines the transmission and reception schedule is one of several pre-shared information groups related to the transmission and reception schedule between the sensor controller 20 and the stylus S. Each information group may include, for example, information such as the duration of a frame (= period UpIntv) and the configuration of each time slot within a frame.

[0048] The MCU 50 pre-stores a group of information about the transmit / receive schedule corresponding to the display in the electronic device 2, and configures the information group in the instruction COM. Furthermore, the MCU 50 determines one or more time slots and frequencies to be allocated to each stylus S based on the number of stylus S in the pair, and configures this in the instruction COM. Thus, the sensor controller 20 can, for example, pair with multiple stylus S simultaneously via time-division multiplexing or frequency-division multiplexing; however, the following explanation assumes communication with only one stylus S.

[0049] The transmitting unit 52 is a circuit that generates a finger detection signal FDS for detecting a finger under the control of the MCU 50. The finger detection signal FDS is, for example, a signal consisting of K pulse trains, each containing K pulses ("1" or "-1" data). Here, K is the number of sensor electrodes 21Y. In addition, the contents of the K pulse trains (i.e., the combination of K pulses) are all different.

[0050] The transmitting unit 53 is a circuit that generates an uplink signal US based on the instruction COM supplied from the MCU 50 and the control signal ctrl_t from the logic unit 51. Specifically, a predetermined preamble is appended to the beginning of the instruction COM supplied from the MCU 50, and the resulting symbol string is spread using a predetermined spreading code (e.g., an 11-chip-length spreading code with autocorrelation characteristics), and further modulated, for example, by cyclic shifting, thereby generating the uplink signal US.

[0051] The selection unit 55 is configured to include a switch 56 and conductor selection circuits 57x and 57y.

[0052] Switch 56 is a switching element configured to connect a common terminal to any one of the terminals T1, T2, D, and R. The T2 terminal is actually a collection of terminals corresponding to the number of sensor electrodes 21Y. The common terminal of switch 56 is connected to the conductor selection circuit 57y, the T1 terminal is connected to the output of the transmitting unit 53, the T2 terminal is connected to the output of the transmitting unit 52, the D terminal is connected to the output of the MCU 50 which outputs the common potential Vcom, and the R terminal is connected to the input of the receiving unit 54.

[0053] The conductor selection circuit 57x is a switching element used to selectively connect multiple sensor electrodes 21X to the input terminal of the receiving unit 54. The conductor selection circuit 57x is configured to also be able to simultaneously connect some or all of the multiple sensor electrodes 21X to the input terminal of the receiving unit 54.

[0054] The conductor selection circuit 57y is a switching element used to selectively connect multiple sensor electrodes 21Y to the common terminal of the switch 56. The conductor selection circuit 57y is also configured to simultaneously connect some or all of the multiple sensor electrodes 21Y to the common terminal of the switch 56. Furthermore, when the T2 terminal within the switch 56 is connected to the common terminal, the conductor selection circuit 57y connects the multiple terminals constituting the T2 terminal and the multiple sensor electrodes 21Y one-to-one.

[0055] Three control signals, sTR, selX, and selY, are supplied from the logic unit 51 to the selection unit 55. Specifically, the control signal sTR is supplied to the switch 56, the control signal selX is supplied to the conductor selection circuit 57x, and the control signal selY is supplied to the conductor selection circuit 57y. By using these control signals sTR, selX, and selY, the logic unit 51 controls the selection unit 55 to transmit the uplink signal US or the finger detection signal FDS, apply the common potential Vcom, and receive the downlink signal DS or the finger detection signal FDS.

[0056] When transmitting the uplink signal US, the logic unit 51 controls the selection unit 55 to simultaneously connect all sensor electrodes 21Y to the input terminal of the transmitting unit 53. As a result, the uplink signal US is transmitted from the entire surface of the touch surface 2a.

[0057] Regarding the reception of the downlink signal DS, the logic unit 51 performs different controls depending on whether it is receiving the downlink signal DS for detecting an undetected stylus S (global scan) or receiving the downlink signal DS from a detected stylus S (local scan). Specifically, firstly, in the case of global scan, the logic unit 51 controls the selection unit 55 to connect all sensor electrodes 21X and 21Y sequentially to the input terminal of the receiving unit 54. Next, in the case of local scan, when the frequency modulation signal T is received, the logic unit 51 first controls the selection unit 55 to connect several sensor electrodes 21X and 21Y located near the indicated position of the stylus S sequentially to the input terminal of the receiving unit 54. Then, when the data signal D is received, the logic unit 55 controls the selection unit 55 to connect the sensor electrode 21X or sensor electrode 21Y closest to the indicated position of the stylus S.

[0058] When transmitting and receiving the finger detection signal FDS, the logic unit 51 controls the selection unit 55 to connect the multiple terminals constituting the T2 terminal of the switch 56 to the multiple sensor electrodes 21Y one-to-one. Then, while maintaining this state, the selection unit 55 is controlled to select one of the multiple sensor electrodes 21X sequentially at a time and connect the selected sensor electrode 21X to the receiving unit 54.

[0059] As understood from the control of the logic unit 51 described so far, communication with the stylus S and detection of the finger's pointing position are performed through time division. Hereinafter, only the communication with the stylus S will be described, but the actual communication with the stylus S is performed while the actions involved in detecting the finger's pointing position are being performed.

[0060] When a common potential Vcom is applied, the logic unit 51 controls the selection unit 55 to simultaneously connect all sensor electrodes 21Y to the D terminal of the switch 56. As a result, the potential of each sensor electrode 21Y is equal to the common potential Vcom.

[0061] The receiving unit 54 is a circuit that receives the finger detection signal FDS sent by the transmitting unit 52 and the downlink signal DS sent by the stylus S based on the control signal ctrl_r of the logic unit 51. When receiving the finger detection signal FDS, the receiving unit 54 acquires K current values ​​for each sensor electrode 21X. For each of the aforementioned K pulse trains, it calculates the inner product of the K pulses constituting the pulse train and the acquired K current values, thereby calculating the detection level at each intersection point of each sensor electrode 21X and each sensor electrode 21Y. Then, based on the result, it determines the area within the touch surface 2a that is being touched (the touch area) and outputs it to the host processor 22 via the MCU 50.

[0062] On the other hand, during the timing of receiving the downlink signal DS, the receiving unit 54 derives the indicated position of the stylus S based on the received intensity of the frequency modulation signal T at each sensor electrode 21X, 21Y, and obtains the data transmitted by the stylus S by demodulating the detected data signal D. Then, the derived indicated position and the obtained data are output to the host processor 22 via the MCU 50.

[0063] Counter 58, connected to MCU 50, is a device that records the elapsed time since it was reset. MCU 50 is configured to reset counter 58 upon receiving the downlink signal DS. Therefore, the elapsed time recorded by counter 58 becomes the elapsed time since MCU 50 last received the downlink signal DS.

[0064] Figure 3(a) is a mode transition diagram showing the action modes of the stylus S. Figure 3 (b) is a mode transition diagram showing the operating modes of the sensor controller 20.

[0065] Firstly, focusing on Figure 3 (a) The stylus S is configured to operate in any of the following modes: discovery mode, operation mode, and communication maintenance mode. Discovery mode is an operation mode that continuously or intermittently receives only the uplink signal US. When the stylus S receives the uplink signal US in discovery mode, it transitions to operation mode.

[0066] The operating mode is an action mode that transmits downlink signal DS and receives the next uplink signal US based on the transmission and reception schedule determined according to the previously received uplink signal US. In the event of a failure to receive uplink signal US in the operating mode (i.e., when the uplink signal US is received but not received despite the attempt to receive it), the stylus S switches to communication maintenance mode.

[0067] The communication sustainment mode is an operating mode used to maintain communication with the sensor controller 20 for a period of time even if the reception of the uplink signal US fails. The specific operation of the stylus S in communication sustainment mode will be described later, but if the uplink signal US is not received in communication sustainment mode and the timeout occurs, the stylus S switches to discovery mode. On the other hand, if the uplink signal US is received in communication sustainment mode, the stylus S returns to operating mode.

[0068] Then focus on Figure 3 (b) The sensor controller 20 operates in any of the following modes: discovery mode, pairing execution mode, and operation mode. Regardless of the mode, the sensor controller 20 transmits the uplink signal US at a constant period and receives the downlink signal DS during the intervals. The transmission period of the uplink signal US consists, for example, one frame as described above.

[0069] Discovery mode is the operating mode before pairing with the stylus S. The sensor controller 20 performs the aforementioned global scan. The uplink signal US transmitted in discovery mode becomes a signal that includes information groups determining the transmission and reception schedule, as well as the allocation of time slots and frequencies. The stylus S, upon receiving the uplink signal US, determines the transmission and reception schedule of the downlink signal DS and the uplink signal US, and transmits the frequency modulation signal T throughout all allocated time slots. Upon receiving the downlink signal DS in discovery mode, the sensor controller 20 transitions to pairing execution mode.

[0070] The pairing execution mode is an operating mode used to establish pairing with the stylus S that sends the downlink signal DS. Upon entering the pairing execution mode, the sensor controller 20 initially performs a global scan, and once the indicated position of the stylus S is detected, it performs a local scan. In this local scan, the sensor controller 20 sends an uplink signal US including a transmission instruction indicating the pen ID. The stylus S, upon receiving the uplink signal US, sequentially transmits a frequency modulation signal T and a data signal D including the pen ID using the time slot and frequency allocated by the uplink signal US. The sensor controller 20 obtains the pen ID by demodulating the received data signal D, establishes pairing with the stylus S by storing it in its built-in memory, and transitions to the operating mode. Furthermore, the sensor controller 20 derives the indicated position of the stylus S based on the received frequency modulation signal T and outputs it to the host processor 22 along with the obtained pen ID.

[0071] The operating mode is a repeated local scanning operation mode. Upon entering the operating mode, the sensor controller 20 derives the indicated position of the stylus S based on the received frequency modulation signal T after transmitting the uplink signal US. Then, it demodulates the received data signal D to obtain the data transmitted by the stylus S, and sequentially outputs the derived indicated position and the obtained data to the host processor 22. Furthermore, if the elapsed time recorded by the counter 58 exceeds a predetermined time, the sensor controller 20 disengages from the stylus S and transitions to the discovery mode.

[0072] Next, regarding the operation of the stylus S and sensor controller 20 in this embodiment, while referring to... Figures 4-7 The sequence shown Figure 1 Let me explain in more detail.

[0073] first, Figure 4 This is a sequence diagram of the actions of the stylus S and the sensor controller 20 when the stylus S approaches the touch surface 2a. In this example, at time t1, the power to the stylus S is turned on, at time t2, a pen stroke is executed (the stylus S and the sensor controller 20 become able to communicate), and at time t3, a pen touch is executed (the tip of the stylus S contacts the touch surface 2a).

[0074] First, the sensor controller 20 is configured to transmit an uplink signal US at a predetermined period UpIntv, and receive a downlink signal DS during the transmission interval of the uplink signal US. It should be noted that... Figure 4 The time interval P5 indicated by "R" corresponds to the aforementioned time slot. At this time, since the sensor controller 20 enters the detection mode, Figure 4The initial uplink signal US shown is a signal that includes information groups that determine the transmission and reception schedule, as well as the allocation of time slots and frequencies.

[0075] After the stylus S is powered on, it continuously or intermittently receives the uplink signal US. Then, when it enters the pen-holding state at time t2, the stylus S becomes capable of receiving the uplink signal US. Figure 4 At time t4, the stylus S is receiving the uplink signal US. It should be noted that the thick circular markers in this and subsequent figures indicate that the stylus S has successfully received the uplink signal US. Furthermore, when the stylus enters the pen touch state at time t3, the pen pressure value detected by the pressure sensor 34 becomes a value greater than 0.

[0076] The stylus S, which receives the uplink signal US at time t4, determines the transmission and reception schedule of the downlink signal DS and the next uplink signal US based on the reception timing of the uplink signal US and the information within the uplink signal US. For example... Figure 4 As shown, the transmit / receive schedule determined in this way becomes the following schedule: Frequency modulation signal T is transmitted in each time slot, and the next uplink signal US is received using the last predetermined time P1 of one cycle. The predetermined time P1 can be the same as the predetermined time P5, or it can be as follows: Figure 4 As shown, the time is longer than the specified time P5. The stylus S, which determines the sending and receiving schedule, enters the operation mode.

[0077] At time t5, the sensor controller 20, having received the initial frequency modulation signal T transmitted by the stylus S according to the transmit / receive schedule, enters the pairing execution mode and then performs a global scan using the received frequency modulation signals T. Thus, the sensor controller 20 derives the initial position of the stylus S. Afterward, the sensor controller 20 transmits an uplink signal US including a transmission command for the stylus ID.

[0078] The stylus S, which receives the uplink signal US at time t6, updates the transmission and reception schedule of the downlink signal DS and the next uplink signal US based on the reception timing of the uplink signal US and the information within the uplink signal US. For example... Figure 4 As shown, the updated transmit and receive schedule becomes the following: First, transmit the frequency modulation signal T, then transmit the data signal D, and use the last specified time P1 of the 1-cycle to receive the next uplink signal US.

[0079] The sensor controller 20 derives the position of the stylus S by performing a local scan using the frequency modulation signal T transmitted by the stylus S. Next, the sensor controller 20 demodulates the data signal D transmitted by the stylus S to obtain the stylus ID transmitted by the stylus S and stores it in its built-in memory. Thus, the sensor controller 20 establishes pairing and transitions to an operating mode.

[0080] Figure 5 This is a sequence diagram showing the actions of the stylus S and sensor controller 20 when both the stylus S and sensor controller 20 are in operating mode, but the stylus S fails to receive the uplink signal US. The thick × markings in this diagram and subsequent diagrams indicate that the stylus S failed to receive the uplink signal US. In this example, the stylus S starts receiving the uplink signal US at time t10 based on the transmit / receive schedule, but fails to receive the uplink signal US even after a specified time P1 has elapsed to time t11.

[0081] In this case, the stylus S enters a communication sustaining mode, continuing to receive the uplink signal US for a specified time P2 consecutive to the specified time P1. The duration of the specified time P2 is not particularly limited, but is preferably set to, for example, 1 / 4 of the period UpIntv. Therefore, even if the reception of the uplink signal US is delayed for some reason, it can still be received, thus reducing the possibility of the stylus S failing to receive the uplink signal US.

[0082] Next, regardless of the content of the unreceived uplink signal US, the stylus S continuously transmits the frequency modulation signal T for a specified time P3 until the start timing of the reception action of the next uplink signal US based on the transmission schedule (i.e., the timing before the specified time P1 from the end of the period UpIntv). The length of the specified time P3 is not particularly limited, but it is preferably set to 1 / 2 of the period UpIntv, for example.

[0083] Here, the sensor controller 20 is configured to not only receive the downlink signal DS from the stylus S as the content requested via the uplink signal US, but also, even if the content of the downlink signal DS received from the stylus S differs from the content requested via the uplink signal US, it will... Figure 2The counter 58 shown is reset. Thus, even while the stylus S is in communication maintenance mode, the sensor controller 20 maintains its operating mode as long as the frequency modulation signal T from the stylus S arrives. Furthermore, the sensor controller 20 is configured to use the downlink signal DS to derive the position of the stylus S, even if the content of the downlink signal DS received from the stylus S differs from the content requested via the uplink signal US. Therefore, as long as the frequency modulation signal T from the stylus S arrives, the sensor controller 20 continues to derive the position of the stylus S.

[0084] The stylus S, having completed the transmission of the frequency modulation signal T, performs the uplink signal US reception operation within a specified time P4. The specified time P4 is set to the value obtained by subtracting the sum of specified times P2 and P3 from the period UpIntv. In one example, if, as mentioned above, specified time P2 is 1 / 4 of the period UpIntv and specified time P3 is 1 / 2 of the period UpIntv, then specified time P4 can be set to 1 / 4 of the period UpIntv. It should be noted that the specified time P4 can also be set to a time longer than specified time P1. In this case, the stylus S begins receiving the uplink signal US before the start timing of the uplink signal US reception operation determined based on the transmit / receive schedule.

[0085] If no uplink signal US is received even after a specified time P4, the stylus S repeatedly performs the aforementioned action starting from the moment the uplink signal US was received within the specified time P2. In this case, the uplink signal US within the specified time P2 is executed consecutively with the uplink signal US within the previous specified time P4.

[0086] exist Figure 5 In the example, at time t12, the stylus S successfully received the uplink signal US. Accepting this, the stylus S updates its transmit / receive schedule and returns to operating mode.

[0087] Figure 6 and Figure 5 Similarly, this is a sequence diagram of the actions of the stylus S and the sensor controller 20 when the stylus S fails to receive the uplink signal US, even though both the stylus S and the sensor controller 20 are in operation mode. Figure 6 The example is that the pen was lifted at moment t13 during the period when the stylus S entered the communication maintenance mode, which is consistent with... Figure 5 The examples are different.

[0088] The stylus S, when entering the communication maintenance mode, is configured to receive the uplink signal US instead of transmitting the frequency modulation signal T when the pen pressure value detected by the pressure sensor 34 indicates that the pen tip is not in contact with the touch surface 2a. As a result, in Figure 6 In this process, after time t13, the transmission of the frequency modulation signal T of the stylus S is stopped. Instead, the uplink signal US is continuously received. This means that the sensor controller 20 no longer deduces the position of the stylus S. Furthermore, the sensor controller 20 returns to the detection mode earlier, but since lifting the stylus S signifies not writing, the likelihood of user dissatisfaction is low. On the other hand, because the period for receiving the uplink signal US is longer compared to transmitting the frequency modulation signal T, the probability of successful reception of the uplink signal US is increased.

[0089] Figure 7 This is a sequence diagram showing the actions of the stylus S and sensor controller 20 when the stylus S, despite performing processing in communication maintenance mode, ultimately fails to receive the uplink signal US. When the stylus S cannot receive the uplink signal US, at time t21, after the series of processing steps in communication maintenance mode (receiving the uplink signal US within a specified time P2, transmitting the frequency modulation signal T within a specified time P3, and receiving the uplink signal US within a specified time P4) have been executed a predetermined number of times, it transitions to discovery mode, ending the processing in communication maintenance mode. Furthermore, at time t20 when the frequency modulation signal T is finally received, the sensor controller 20... Figure 2 The counter 58 shown is reset. Then, at the moment t22 when the elapsed time recorded by the counter 58 exceeds the specified time P6, the pairing with the stylus S is released, and the system returns to discovery mode.

[0090] Next, regarding the operation of the stylus S and sensor controller 20 in this embodiment, while referring to... Figures 8-13 The processing flow shown Figure 1 Let me explain in further detail.

[0091] Figures 8-11 These are flowcharts illustrating the processing flow of the stylus S. These diagrams show the process by which the stylus S is processed. Figure 1 The processing circuit 30 shown performs the processing.

[0092] First refer to Figure 8The stylus S, now powered on, enters discovery mode (step S1) and begins receiving uplink signal US (step S2). Then, it determines whether the uplink signal US has been received through this receiving action (step S3). The stylus S repeatedly performs step S3 until it is determined that the uplink signal US has been received. If it is determined that the uplink signal US has been received, the receiving action of the uplink signal US stops (step S4). It should be noted that the stylus S can execute the receiving action of the uplink signal US, which begins in step S2, continuously or intermittently. In this case, to reliably receive the uplink signal US when within the receptive zone, it is preferable to set the duration of one receiving action to be longer than the aforementioned period UpIntv.

[0093] Upon receiving the uplink signal US, the stylus S then determines the transmission and reception schedule of the downlink signal DS and the next uplink signal US based on the reception timing of the uplink signal US and the information within the uplink signal US (step S5). Then, the stylus S enters the operation mode (step S6).

[0094] The stylus S, having entered operation mode, follows the predetermined send / receive schedule, such as... Figure 9 As shown, it continuously determines whether the transmission timing of the downlink signal DS has arrived (step S10) and whether the reception timing of the uplink signal US has arrived (step S11).

[0095] In step S10, the stylus S, upon determining that the transmission timing of the downlink signal DS has arrived, begins transmitting the downlink signal DS as indicated by the uplink signal US (step S12). The downlink signal DS transmitted in this way is either the aforementioned frequency modulation signal T or the data signal D, and its duration is pre-adjusted to ensure transmission is completed within the period indicated by the transmit / receive schedule (i.e., the aforementioned time slot). Afterward, the stylus S determines whether the transmission of the downlink signal DS has been completed (step S13). If it is determined to be completed, the process returns to the determination in steps S10 and S11.

[0096] On the other hand, the stylus S, which determines in step S11 that the uplink signal US reception timing has arrived, begins the uplink signal US reception operation (step S14). Then, the stylus S determines whether it has received the uplink signal US (step S15). If it is determined that it has not received it, it further determines whether a predetermined time P1 has elapsed since the start of the reception operation (step S16). As a result, if it is determined that the time has not elapsed, it returns to step S15 and continues the determination process; otherwise, if it is determined that the time has elapsed, the process moves to... Figure 10 Step S30.

[0097] In step S15, it is determined that the stylus S has stopped receiving the uplink signal US (step S18). Based on the reception timing of the newly received uplink signal US and the information within that uplink signal US, the transmission and reception schedules of the downlink signal DS and the next uplink signal US are updated (step S19). Then, the stylus S acquires and transmits data according to the instructions contained in the uplink signal US (step S20), and the process returns to the determination in steps S10 and S11. The data acquired in step S20 is configured in the data signal D transmitted in the subsequent step S12, either in a combined or segmented manner.

[0098] exist Figure 10 In step S30, the stylus S enters the communication maintenance mode. Then, based on the latest transmit / receive schedule determined in step S5 or step S19, the aforementioned predetermined times P2, P3, and P4 are determined (step S31). Typically, based on the period UpIntv represented by the transmit / receive schedule, P2 can be set to UpIntv / 4, P3 to UpIntv / 2, and P4 to UpIntv / 4.

[0099] Next, the stylus S substitutes 1 into the variable n, which represents the number of times the uplink signal US is received within a specified time P2, the frequency modulation signal T is transmitted within a specified time P3, and the uplink signal US is received within a specified time P4 (step S32), and determines whether the pen pressure value detected by the pressure sensor 34 is 0 (step S33).

[0100] If the pen pressure value is determined to be 0 in step S33, the stylus S will then repeatedly determine whether it has received the uplink signal US during the specified time period P2+P3+P4 (steps S34 and S35). Figure 9 Step S17. (As shown) Figure 9 As shown, the stylus S enters the operation mode in step S17, and the processing moves to step S18. The stylus S then operates in operation mode. On the other hand, the stylus S, which determines in step S35 that a predetermined time P2+P3+P4 has elapsed, increments the variable n by 1 (step S36) and compares the variable n with a predetermined value N (step S37). As a result, if n > N, the processing returns to normal. Figure 8 Step S1. Thus, the stylus S returns to discovery mode. On the other hand, if n is not greater than N, the stylus S will return to step S33 and continue processing in communication maintenance mode.

[0101] If the pen pressure value is not 0 in step S33, then... Figure 11As shown, the stylus S repeatedly determines whether it has received the uplink signal US during the period until a predetermined time P2 has elapsed (steps S40 and S41). If it is determined in step S40 that the uplink signal US has been received, the stylus S will move the processing direction to... Figure 9 Step S17. The subsequent processing is as described above. On the other hand, in step S41, it is determined that the stylus S, after a predetermined time P2 has elapsed, stops receiving the uplink signal US (step S42) and begins transmitting the frequency modulation signal T (step S43). Afterwards, the stylus S continues transmitting the frequency modulation signal T, and after a predetermined time P3 has elapsed since the uplink signal US stopped in step S42 (step S44), it stops transmitting the frequency modulation signal T (step S45).

[0102] The stylus S, which had stopped transmitting the frequency modulation signal T, resumes receiving the uplink signal US (step S46). Then, during the specified time P4, it repeatedly determines whether the uplink signal US has been received (steps S47 and S48). If it is determined in step S47 that the uplink signal US has been received, the stylus S moves the processing direction to... Figure 9 Step S17. The subsequent processing is as described above. On the other hand, in step S48, if the stylus S determines that a predetermined time P4 has elapsed, the variable n is incremented by 1 (step S49), and the variable n is compared with a predetermined value N (step S50). As a result, if n > N, the processing is returned. Figure 8 Step S1. Therefore, the stylus S returns to discovery mode. On the other hand, if n is not greater than N, the stylus S will process and return... Figure 10 Step S33 continues the processing in the communication maintenance mode.

[0103] then, Figure 12 and Figure 13 These are process flow diagrams illustrating the processing flow of the sensor controller 20. These diagrams show the process flow of the sensor controller 20. Figure 2 The processing performed by the MCU50 shown.

[0104] First refer to Figure 12 The power supply is turned on, and the sensor controller 20 enters the discovery mode (step S60), determining the transmission and reception schedule of the uplink signal US and the downlink signal DS (step S61). This determination can be made, for example, by allocating the transmission of the uplink signal US and the reception of the downlink signal DS to each time slot within a frame.

[0105] Next, the sensor controller 20 continuously determines, according to the determined transmit / receive schedule, whether the transmission timing of the uplink signal US has arrived (step S62) and whether the reception timing of the downlink signal DS has arrived (step S63).

[0106] In step S62, the sensor controller 20, having determined that the transmission timing for the uplink signal US has arrived, begins transmitting the uplink signal US (step S64). Furthermore, after the transmission of the uplink signal US is completed, the process returns to the determination steps S62 and S63.

[0107] In step S63, the sensor controller 20, having determined that the timing for receiving the downlink signal DS has arrived, begins the downlink signal DS receiving operation (step S66). Afterward, the sensor controller 20 repeatedly determines whether the downlink signal DS has been received during a predetermined time P5, which is one time slot long (steps S67, S68).

[0108] If it is determined in step S67 that a downlink signal DS has been received, the sensor controller 20 will shift the processing direction to... Figure 13 Step S80. On the other hand, in step S68, the sensor controller 20 determines that a predetermined time P5 has elapsed. Figure 2 The counter 58 indicates whether the elapsed time has reached the specified time P6 (step S69). If not, the process returns to the determination process in steps S62 and S63. On the other hand, if the time has reached, the current operation mode is determined (step S70). Furthermore, if the current operation mode is the discovery mode, the process returns to the determination process in steps S62 and S63. If the current operation mode is another mode, and it is in the process of pairing, the pairing ends, and after entering the discovery mode (step S71), the process returns to the determination process in steps S62 and S63.

[0109] Reference Figure 13 In step S80, the sensor controller 20 determines whether the received downlink signal DS is the content requested by the uplink signal US (step S80). For example, if the instruction in the uplink signal US instructs the transmission of the frequency modulation signal T in the first two time slots and the transmission of the data signal D including the pen pressure value in the subsequent time slots, if the received downlink signal DS is such content, the determination result of step S80 is affirmative; if it is not such content, the determination result of step S80 is negative.

[0110] After obtaining a positive result in step S80, the sensor controller 20 resets the counter 58 (step S81) and determines the current operating mode (step S82). If the result is that the detection mode is being entered, then after entering the pairing mode (step S83), it returns to the determination process in steps S62 and S63.

[0111] Additionally, if pairing mode is entered, pairing processing is performed (step S84). This pairing processing includes determining the instruction configured in the subsequently transmitted uplink signal US and various processing steps on the downlink signal DS transmitted by the stylus S based on the received instruction (deriving the position based on the results of global and local scanning and outputting the derived position to the host processor 22, acquiring the pen ID transmitted by the stylus S, etc.). Next, the sensor controller 20 determines whether pairing has been established as a result of the pairing processing (step S85). The result of this determination is affirmative if the pen ID reception is completed, and negative if the pen ID reception is not completed.

[0112] After the sensor controller 20 receives a positive result in step S85 and enters the operation mode (step S86), it returns to the determination process in steps S62 and S63. On the other hand, if the sensor controller 20 receives a negative result in step S85, it then returns to the determination process in steps S62 and S63 while in the pairing mode.

[0113] In step S82, the sensor controller 20, which determines that the current operating mode is the operation mode, performs the derivation of the position of the stylus S and the acquisition of the stylus S's transmission data based on the received downlink signal DS (step S87). It should be noted that when multiple time slots are needed to receive the frequency modulation signal T to derive the position of the stylus S, the sensor controller 20 stores the received intensity of the frequency modulation signal T at each sensor electrode 21X, 21Y in each time slot. After the reception in the last time slot is completed, the position is derived based on the stored received intensity. Similarly, when multiple time slots are needed to receive the data signal D to acquire the transmission data of the stylus S, the sensor controller 20 stores fragments of the transmission data in each time slot. After the reception in the last time slot is completed, the stored fragments are summarized as a single transmission data to be acquired. After the sensor controller 20 outputs the derived position and acquired transmission data to the host processor 22 (step S88), it returns to the determination process in steps S62 and S63.

[0114] If the sensor controller 20 receives a negative result in step S80, it resets the counter 58 in the same way as if it received a positive result (step S90). In this way, pairing with the stylus S can continue even if the stylus S does not send the required signal. It should be noted that in... Figure 13 In the process, the counter 58 is reset through each of steps S81 and S90, but the counter 58 can also be reset before the determination in step S80.

[0115] Next, the sensor controller 20 derives the position of the stylus S based on the received signal (frequency modulation signal T) (step S91) and outputs the derived position to the host processor 22 (step S92). Similarly, in step S91, if the frequency modulation signal T needs to be received in multiple time slots to derive the position of the stylus S, the sensor controller 20 stores the received intensity of the frequency modulation signal T at each sensor electrode 21X, 21Y in each time slot. After the reception in the last time slot ends, the position is derived based on the stored received intensity. Additionally, in step S92, the sensor controller 20 may also output the previously obtained pen pressure value (the latest pen pressure value obtained during the period when the stylus S is in operation mode) to the host processor 22 along with the derived position. Afterwards, the sensor controller 20 returns to the decision processing in steps S62 and S63.

[0116] As explained above, the stylus S and sensor controller 20 according to this embodiment can reduce the possibility of the stylus S failing to receive the uplink signal US, and from this point of view, it can also avoid the phenomenon of suddenly becoming unable to write during writing.

[0117] Furthermore, according to this embodiment, even if the reception of the uplink signal US fails, the stylus S continues to transmit the frequency modulation signal T from the stylus S. Therefore, the sensor controller 20 can continue to detect the position of the stylus S, and pairing decoupling can be avoided. Thus, the phenomenon of suddenly becoming unable to write during writing can be avoided.

[0118] Furthermore, according to this embodiment, when the pen pressure value is >0, instead of transmitting a data signal D including the pen pressure value, a frequency modulation signal T is transmitted. Therefore, compared to a modulated wave formed by modulating the frequency modulation signal with the pen pressure value (e.g., a modulated wave modulated by OOK, ASK, or PSK), it becomes a continuous signal, or the frequency is fixed, thus improving the detectability in the sensor controller 20. Therefore, the possibility of the sensor controller 20 detecting the pen S in noisy environments such as where the uplink signal US cannot be detected is increased. It should be noted that during the period when the pen S transmits the frequency modulation signal T instead of the data signal D including the pen pressure value, the sensor controller 20 may also output the last obtained pen pressure value as the currently obtained pen pressure value, along with the position obtained during that period, to the host processor 22.

[0119] While the preferred embodiments of the present invention have been described above, the present invention is not limited to such embodiments in any way, and the present invention can certainly be implemented in various ways without departing from its spirit.

[0120] For example, in the above embodiment, when the pen pressure value is >0, a frequency modulation signal T is sent from the stylus S instead of a data signal D including the pen pressure value. However, even when the pen pressure value is >0, a data signal D including the pen pressure value (a signal modulated by the pen pressure value) can be sent. In this case, the detectability of the stylus S by the sensor controller 20 decreases compared to the case of sending the frequency modulation signal T, but the sensor controller 20, which continues to operate normally, requests normal communication (including the transmission of the data signal D including the pen pressure value) from the stylus S with a high probability, so the system as a whole can continue to operate.

[0121] Regardless of whether the data signal D or the frequency modulation signal T is transmitted in the communication maintenance mode, from the perspective of the host processor 22, it appears as if the stylus S and the sensor controller 20 are operating normally, even if the uplink signal US is not actually detected by the stylus S. Therefore, a robust system including the stylus S and the sensor controller 20 can be provided. Thus, the unpleasant phenomenon of "the uplink signal US, which is not needed for communication, cannot be detected despite being in the correct position, resulting in a line interruption" can be avoided.

[0122] in addition, Figure 14 This is a sequence diagram illustrating the operation of the stylus S and sensor controller 20 in a modified embodiment of this invention. The stylus S in this modified embodiment... Figure 10 The step S31, which determines the specified times P2, P3, and P4 based on a period UpIntv' that is different from the period UpIntv in the above-described embodiment, differs from the stylus S in that it is based on a period UpIntv' that is different from the period UpIntv. It should be noted that in Figure 14The case where UpIntv' < UpIntv is shown, but it can also be set to UpIntv' > UpIntv. Additionally, in Figure 14 an example where P2 = UpIntv' / 4, P3 = UpIntv' / 2, and P4 = UpIntv' / 4 is shown, but any one or more of the specified times P2, P3, and P4 can be set to values different from those in the above-described embodiment. By doing so, in the case where the stylus S becomes unable to receive the uplink signal US due to the timing of the reception operation of the uplink signal US by the stylus S and the timing of the transmission operation of the uplink signal US by the sensor controller 20 being staggered, the uplink signal US can be received shortly thereafter.

[0123] Reference Numeral Explanation

[0124] 2 Electronic Device

[0125] 2a Touch Surface

[0126] 20 Sensor Controller

[0127] 21 Touch Sensor <000,0333>?

[0128] 21X, 21Y Sensor Electrodes

[0129] 22 Host Processor

[0130] 30 Processing Circuit

[0131] 31 Battery

[0132] 32 Core <, ?

[0133] 33 Pen Electrode

[0134] 34 Pressure Sensor

[0135] 51 Logic Unit

[0136] 52, 53 Transmitting Units

[0137] 54 Receiving Unit

[0138] 55 Selection Unit

[0139] 56 Switch

[0140] 57x, 57y Conductor Selection Circuits

[0141] 58 Counter

[0142] ctrl_t, ctrl_r, sTR, selX, selY Control Signals

[0143] D Data Signal

[0144] There are some question marks in the translation where the original text seems to have some unclear or incorrect formatting in the tags. Please check and correct the original text if possible for a more accurate translation.DS downlink signal

[0145] FDS finger detection signal

[0146] P1~P6 First~Sixth Scheduled Time

[0147] S stylus

[0148] T frequency modulation signal

[0149] UpIntv uplink signal US transmission period

[0150] US uplink signal

[0151] Vcom is a shared potential.

Claims

1. An integrated circuit for controlling a stylus, the integrated circuit comprising electronic circuitry configured as follows: Operate in the first mode to receive a first signal sent from the sensor controller; In response to receiving the first signal, switch from the first mode to the second mode; Operating in the second mode, it performs bidirectional communication with the sensor controller based on a first schedule configured according to the first signal, and performs a receiving action to receive a second signal sent from the sensor controller after the first signal; and In response to the failure to receive the second signal according to the receiving action of the first schedule, the system switches from the second mode to the third mode to perform the receiving action based on a second schedule different from the first schedule.

2. The integrated circuit according to claim 1, wherein the electronic circuit is configured as follows: In response to receiving the second signal based on the second schedule, switch from the third mode to the second mode.

3. The integrated circuit according to claim 1, wherein the electronic circuit is configured as follows: When the third mode times out, switch back to the first mode.

4. The integrated circuit according to claim 1, wherein the electronic circuit is configured as follows: Based on the first schedule, the receiving action is executed within the first time period; and Based on the second schedule, the receiving action is performed within a second time period that is longer than the first time period.

5. The integrated circuit according to claim 4, wherein: The first time period begins at the first moment and ends at the second moment; and The second time begins at the first time and ends at the third time, which is later than the second time.

6. The integrated circuit according to claim 4, wherein: The first time period begins at the first moment and ends at the second moment; and The second time begins at the fourth time, which is later than the second time, and ends at the fifth time.

7. A method performed by a stylus, the method comprising: Operate in the first mode to receive the first signal sent by the sensor controller; In response to receiving the first signal, switch from the first mode to the second mode; Operating in the second mode, it performs bidirectional communication with the sensor controller based on a first schedule configured according to the first signal, and performs a receiving action to receive a second signal sent from the sensor controller after the first signal; and In response to the failure to receive the second signal during the receiving action based on the first schedule, the system switches from the second mode to the third mode to perform the receiving action based on a second schedule different from the first schedule.

8. The method of claim 7, comprising: In response to receiving the second signal based on the second schedule, switch from the third mode to the second mode.

9. The method according to claim 7, comprising: When the third mode times out, switch back to the first mode.

10. The method of claim 7, comprising: Based on the first schedule, the receiving action is executed within the first time period; and Based on the second schedule, the receiving action is performed within a second time period that is longer than the first time period.

11. The method of claim 10, wherein: The first time period begins at the first moment and ends at the second moment; and The second time begins at the first time and ends at the third time, which is later than the second time.

12. The method according to claim 10, wherein: The first time period begins at the first moment and ends at the second moment; and The second time begins at the fourth time, which is later than the second time, and ends at the fifth time.

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