System including a pen and a touch controller, method executed by the pen, pen, and touch controller

Abstract

An active pen 2 and a touch controller 31 are configured to transmit / receive signals to / from each other by using a frame F including a plurality of time slots TS0-TSm which are temporally spaced apart. The active pen 2 and the touch controller 31 are each configured to be able to transmit and detect a reference signal for synchronizing a frame position which is the temporal position of the frame F, and are each configured to acquire the frame position on the basis of the reference signal when the reference signal is detected, and operate in accordance with the acquired frame position. The active pen 2 and the touch controller 31 are also configured to be able to transmit and detect a reference signal for synchronizing the temporal position of the frame F. The active pen 2 is configured to transmit a reference change signal CH indicating that the active pen itself would become a synchronization master when the synchronization master is to be changed.

Description

Technical Field

[0001] The present invention relates to a system including a pen and a touch controller, a method executed by the pen, the pen, and the touch controller.

Background Art

[0002] In a position detection system that performs unidirectional communication from a pen to a touch controller, there is a system that synchronizes the touch controller with the pen by a signal transmitted by the pen (hereinafter referred to as "pen signal"). Patent Document 1 discloses an example of such a position detection system.

[0003] In the unidirectional communication position detection system as described above, the pen may transmit a pen signal that is not necessary, resulting in wasted power consumption. For example, when the touch controller performs pen detection in a time-division manner with finger touch detection or driving of pixels included in the display, the pen signal transmitted outside the period when the touch controller performs pen detection will not be received by the touch controller even if the pen transmits it, and thus it is a pen signal that does not need to be transmitted. Therefore, in recent years, a position detection system that performs bidirectional communication between the pen and the touch controller has emerged. According to bidirectional communication, the pen can transmit a pen signal when the touch controller needs the pen signal, so it is possible to avoid the above-mentioned wasted power consumption. Patent Documents 2 and 3 disclose examples of position detection systems that perform bidirectional communication between the pen and the touch controller.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] By the way, in a position detection system that performs bidirectional communication between a pen and a touch controller, a frame including a plurality of time slots is used. The touch controller transmits an uplink signal at the head of each frame, and the pen transmits a pen signal using one or more of each time slot. The structure of the frame and the time slots used by the pen are predetermined by the protocol. The uplink signal has a role of indicating the temporal position of the frame (hereinafter referred to as "frame position"), and the pen acquires the frame position based on the reception timing of the uplink signal, and according to the acquired frame position, the transmission timing of the pen signal and the reception timing of the next uplink signal are determined.

[0006] Here, the pen may fail to receive the uplink signal due to the influence of external noise or the like. Then, the pen cannot acquire the frame position and cannot transmit the pen signal, and as a result, the drawing of the input stroke stops, so-called disconnection occurs. Therefore, the inventor of the present application has considered configuring the pen so that the pen signal can be transmitted even if the reception of the uplink signal fails by diverting the frame position acquired based on the latest received uplink signal to the frame in which the uplink signal could not be received.

[0007] However, since the frequencies of the clock signals of the pen and the touch controller do not usually completely match, if the pen transmits the pen signal by diverting the frame position as described above, the timing gradually shifts, making it difficult for the touch controller to receive. Therefore, there is a need for further technology to avoid interruption of stroke drawing even if the pen fails to receive the uplink signal.

[0008] Accordingly, one object of the present invention is to provide a system including a pen and a touch controller, a method executed by the pen, a pen, and a touch controller that can avoid disconnection when the pen fails to receive an uplink signal.

Means for Solving the Problem

[0009] A system according to the present invention is a system including a pen and a touch controller, wherein the pen and the touch controller are configured to transmit and receive signals to and from each other using a frame including a plurality of pen detection periods separated in time, and the pen and the touch controller are each configured to be able to transmit and detect a reference signal for synchronizing frame positions, and when the reference signal is detected, the frame position is acquired based on the reference signal and the operation is performed according to the acquired frame position, and the pen is configured to transmit a reference change signal indicating that itself becomes the master of the synchronization when changing the master of the synchronization.

[0010] A method according to the present invention is a method executed by the pen in a system including a pen and a touch controller, the method including: performing a next detection operation of the reference signal according to a frame position acquired based on a reference signal transmitted by the touch controller; determining whether the reference signal is received by the detection operation; and transmitting a reference change signal indicating that itself becomes the master of the synchronization of the frame position when it is determined that the reference signal is not received by the detection operation.

[0011] The pen according to the present invention has an integrated circuit and a pen tip electrode, and is a pen that communicates bidirectionally with a touch controller. The integrated circuit performs a detection operation of the next reference signal using the pen tip electrode according to a frame position obtained based on a reference signal transmitted by the touch controller, determines whether the reference signal is received by the detection operation, and when it is determined that the reference signal is not received by the detection operation, transmits a reference change signal indicating that itself becomes the master of the synchronization of the frame position from the pen tip electrode.

[0012] The touch controller according to the present invention is a touch controller that derives the position of the pen by communicating bidirectionally with the pen via a sensor. When a reference change signal indicating that it becomes the master of the synchronization of the frame position is received from the pen, it acquires the frame position according to a reference signal for synchronizing the frame position transmitted by the pen, and based on the acquired frame position, performs a detection operation of a downlink signal transmitted by the pen and transmits an uplink signal to the pen.

Advantages of the Invention

[0013] According to the present invention, the pen can be made the master of frame synchronization as needed, so it is possible to avoid a disconnection when the pen fails to receive an uplink signal.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Mode for Carrying Out the Invention

[0015] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0016] FIG. 1 is a diagram showing the configuration of a position detection system 1 according to an embodiment of the present invention. As shown in the figure, the position detection system 1 includes an active pen 2 and an electronic device 3 which is a position detection device for detecting the active pen 2.

[0017] The electronic device 3 is a computer having a touch surface 3a such as a tablet computer or a digitizer. Inside the electronic device 3, a sensor 30 disposed immediately below the touch surface 3a, a touch controller 31 connected to the sensor 30, a display 32 disposed so as to overlap the sensor 30, and a host processor 33 for controlling each part of the electronic device 3 including these are provided.

[0018] The host processor 33 is the central processing unit of the electronic device 3, and is configured to read various programs from a memory (not shown) and execute them. The programs thus executed include various applications such as the operating system and drawing applications of the electronic device 3. Among these, the drawing application is a program for generating digital ink based on the position and data acquired by the touch controller 31, storing the digital ink in the memory in the electronic device 3, rendering the generated digital ink, and generating a video signal indicating the result and supplying it to the display 32. The display 32 is a device that displays the video signal supplied from the host processor 33, and is constituted by, for example, a liquid crystal display or an organic EL display.

[0019] The sensor 30 is a device having a structure in which a plurality of sensor electrodes are arranged in the touch surface 3a. The plurality of sensor electrodes include a plurality of X electrodes each extending along the Y direction in the touch surface 3a and juxtaposed at equal intervals along the X direction orthogonal to the Y direction in the touch surface 3a, and a plurality of Y electrodes each extending along the X direction and juxtaposed at equal intervals along the Y direction.

[0020] A part of the plurality of sensor electrodes constituting the sensor 30 can be used also as a common electrode of the display 32 (an electrode for commonly supplying a ground potential to each pixel). When this dual use is performed, the electronic device 3 constitutes a so-called "in-cell type" position detection device. On the other hand, when the dual use is not performed, the electronic device 3 constitutes a so-called "on-cell type" or "out-cell type" position detection device. Although the present invention can be suitably applied to any of the electronic devices 3, hereinafter, the description will be continued assuming that the electronic device 3 is an in-cell type position detection device.

[0021] The touch controller 31 is an integrated circuit having a function of detecting the positions of the active pen 2 and the passive pointer (for example, a human finger) in the touch surface 3a. Specifically, it is configured to detect the position of the active pen 2 by the active electrostatic method and detect the position of the passive pointer by the capacitance method.

[0022] Regarding the position detection of the active pen 2 by the active electrostatic method in detail, the touch controller 31 derives the position of the active pen 2 within the touch surface 3a and performs a process of acquiring data from the active pen 2 by communicating bidirectionally with the active pen 2 via the sensor 30. Hereinafter, the signal transmitted from the touch controller 31 to the active pen 2 in this bidirectional communication is referred to as an "uplink signal US", and the signal transmitted from the active pen 2 to the touch controller 31 is referred to as a "downlink signal DS".

[0023] The downlink signal DS is a kind of the pen signal described above. In the present embodiment, in addition to the "downlink signal DS", a "reference change signal CH" is also included in the pen signal, which will be described later. The touch controller 31 transmits the uplink signal US by changing the potential of each sensor electrode constituting the sensor 30, while receives the downlink signal DS and the reference change signal CH by detecting the change in the potential at each sensor electrode constituting the sensor 30.

[0024] The touch controller 31 sets a frame based on the information of the time when the pixels are not driven by the display 32 (hereinafter referred to as "blank time"), and arranges a plurality of time slots (a plurality of pen detection periods separated in time), which are periods for the touch controller 31 to detect pen signals, and a plurality of passive pointer detection periods, which are periods for the touch controller 31 to detect passive pointers, therein. The touch controller 31 receives the pen signal within each time slot and performs a process for detecting the passive pointer within each passive pointer detection period.

[0025] The information on the blank time is notified from the host processor 33 to the touch controller 31. The touch controller 31 determines the frame position based on the information on the blank time notified from the host processor 33, and arranges the plurality of time slots and the plurality of passive pointer detection periods described above within the frame. Usually, each frame is configured to include a plurality of blank times, and the plurality of time slots and the plurality of passive pointer detection periods are arranged in a distributed manner within each blank period.

[0026] Here, the communication protocol that defines the communication method between the active pen 2 and the touch controller 31 is configured to have a plurality of patterns in advance that indicate different temporal arrangements of the time slots and the passive pointer detection periods within the frame. The touch controller 31 is configured to arrange the plurality of time slots and the plurality of passive pointer detection periods within the frame by selecting one of the plurality of patterns based on the information on the blank time notified from the host processor 33. Further, the touch controller 31 also performs a process of notifying the active pen 2, by a command in the uplink signal US, of the selected pattern and information indicating the time slot that the active pen 2 should actually use for transmitting the pen signal.

[0027] The uplink signal US functions as a reference signal for notifying the active pen 2 of the above-described frame position from the touch controller 31 and also has the role of transmitting a command for controlling the active pen 2 from the touch controller 31. The touch controller 31 is configured to transmit the uplink signal US at the head of the frame, and the active pen 2 is configured to acquire the frame position based on the reception timing of the uplink signal US. Further, the active pen 2 is configured to acquire from the command included in the uplink signal US information indicating the structure of the frame (such as the temporal arrangement of a plurality of time slots) and the time slots that the active pen 2 should actually use for transmitting the pen signal. Hereinafter, the frame position, the structure of the frame, and the information indicating the time slots may be collectively referred to as the "transmission / reception schedule".

[0028] The downlink signal DS is a signal including a position signal that is an unmodulated carrier signal and a data signal that is a carrier signal modulated by various data such as a pen pressure value and switch information described later. The active pen 2 is configured to transmit the downlink signal DS according to the transmission / reception schedule acquired based on the uplink signal US. The touch controller 31 derives the position of the active pen 2 based on the distribution of the reception intensity of the position signal at each of the plurality of sensor electrodes constituting the sensor 30, and receives and demodulates the data signal using the sensor electrode closest to the derived position among the plurality of sensor electrodes to acquire the data transmitted by the active pen 2.

[0029] As shown in FIG. 1, the active pen 2 includes a core body 20, a pen tip electrode 21, a pressure sensor 22, a side switch 23, a battery 24, and an integrated circuit 25. The core body 20 is a member constituting the pen shaft of the active pen 2. The tip of the core body 20 constitutes the pen tip of the active pen 2, and the end is in contact with the pressure sensor 22. The pen tip electrode 21 is a conductor provided at the tip (pen tip) of the core body 20 and is electrically connected to the integrated circuit 25.

[0030] The pressure sensor 22 is a sensor that detects the pressure applied to the pen tip. The pressure detected by the pressure sensor 22 is supplied to the integrated circuit 25 as, for example, a 12-bit pen pressure value. The side switch 23 is a push-button type switch provided on the surface of the active pen 2 and is configured to be operable to be turned on and off by the user. The operation state (on / off state) of the side switch 23 is supplied to the integrated circuit 25 as, for example, 2-bit switch information. The battery 24 serves to supply the power necessary for the integrated circuit 25 to operate.

[0031] The integrated circuit 25 is a circuit that executes processes such as receiving the uplink signal US, generating and transmitting the downlink signal DS and the reference change signal CH. The integrated circuit 25 receives the uplink signal US by detecting a change in the potential of the pen tip electrode 21, while transmitting a pen signal (specifically, the above-described downlink signal DS and reference change signal CH) by applying a change to the potential of the pen tip electrode 21.

[0032] Figure 2 is a state transition diagram of the integrated circuit 25. As shown in the figure, the integrated circuit 25 is configured to operate in any one of a discovery mode, a slave mode, and a master mode. The initial state is the discovery mode, and the integrated circuit 25 that has entered the discovery mode continuously or intermittently performs a detection operation of the uplink signal US (step S1).

[0033] When the uplink signal US is detected as a result of the detection operation in step S1 (step S2), the integrated circuit 25 enters the slave mode and acquires the above-described transmission / reception schedule based on the received uplink signal US. Subsequently, the integrated circuit 25 transmits the downlink signal DS according to the acquired transmission / reception schedule (step S10). Also, when the arrival of the end timing of the frame is indicated by the acquired transmission / reception schedule (step S11), the detection operation of the next uplink signal US is performed (step S12). As a result, when the uplink signal US is detected (step S13), the integrated circuit 25 acquires the transmission / reception schedule again based on the uplink signal US and repeats the process of step S10.

[0034] On the other hand, when the integrated circuit 25 does not detect the uplink signal US as a result of the detection operation in step S12, it enters the master mode (step S14). The integrated circuit 25 that has entered the master mode diverts the latest acquired transmission / reception schedule to the current frame (the frame in which the transmission of the uplink signal US that could not be detected was executed). In one example, the integrated circuit 25 may acquire the transmission / reception schedule for the current frame by shifting the latest acquired transmission / reception schedule backward by a time equal to the time length UpIntv of the frame.

[0035] The transmission / reception schedule thus acquired by the integrated circuit 25 may be different from the transmission / reception schedule determined inside the touch controller 31. Therefore, the integrated circuit 25 transmits a reference change signal CH indicating that it becomes the master of synchronization (frame synchronization) at the time slot at the head of the current frame (hereinafter referred to as the "head slot") (step S20). In the present embodiment, the head slot of each frame is reserved for transmitting the reference change signal CH and is not used for transmitting the downlink signal DS. Therefore, the integrated circuit 25 that has entered the slave mode sets the head slot to mute (a state where no signal is transmitted).

[0036] Thereafter, the integrated circuit 25 transmits the downlink signal DS according to the acquired transmission / reception schedule (step S21). When the arrival of the end timing of the frame is indicated by the acquired transmission / reception schedule (step S22), the integrated circuit 25 performs a detection operation for the next uplink signal US (step S23). As a result, when the uplink signal US is not detected (step S24), the integrated circuit 25 determines whether or not a predetermined time has elapsed since the uplink signal US was last detected. If it is determined that the time has elapsed, the integrated circuit 25 returns to the discovery mode and executes the processing from step S1 (step S24). On the other hand, if it is determined that the time has not elapsed, the processing from step S20 is repeated (step S25). In this case, the integrated circuit 25 is configured to acquire the transmission / reception schedule for the current frame based on the latest transmission / reception schedule that can be acquired, similar to when it enters the master mode.

[0037] The integrated circuit 25 that has detected the uplink signal US in step S23 returns to the slave mode and executes the processing from step S10 (step S26). That is, the uplink signal US transmitted by the touch controller 31 has a function as a reference change signal indicating that the touch controller 31 becomes the master of synchronization. The integrated circuit 25 that has received the uplink signal US as this reference change signal aborts being the master of synchronization and returns to the slave. In this case, the integrated circuit 25 will acquire the transmission / reception schedule for the current frame based on the newly received uplink signal US.

[0038] FIG. 3 is a state transition diagram of the touch controller 31 corresponding to the state transition of the integrated circuit 25 shown in FIG. 2. As shown in the figure, the touch controller 31 is also configured to operate in any one of a discovery mode, a slave mode, and a master mode. The initial state is the discovery mode, and the touch controller 31 that has entered the discovery mode determines a transmission / reception schedule based on the blank time information supplied from the host processor 33, and then transmits an uplink signal US at the head of a frame (step S30). After the transmission of the uplink signal US is completed (step S31), a downlink signal DS is detected in each time slot (step S32). Note that the touch controller 31 entering the discovery mode does not have to perform a detection operation of the reference change signal CH.

[0039] If the end timing of the frame arrives without detecting the downlink signal DS as a result of the detection operation in step S32 (step S33), the touch controller 31 determines a transmission / reception schedule again, returns to step S30, and repeats the transmission of the uplink signal US. At this time, the touch controller 31 may determine the transmission / reception schedule for the current frame by shifting the latest determined transmission / reception schedule backward by a time equal to the time length UpIntv of the frame (see FIGS. 4 and 5), or may determine the transmission / reception schedule again based on the blank time information newly supplied from the host processor 33 or previously supplied.

[0040] On the other hand, the touch controller 31 that has detected the downlink signal DS as a result of the detection operation in step S32 enters the master mode (step S34). The touch controller 31 that has entered the master mode transmits an uplink signal US with the active pen 2 that has transmitted the downlink signal DS as a communication partner (step S40), and after the transmission is completed (step S41), performs a detection operation of the reference change signal CH and the downlink signal DS (step S42).

[0041] When the reference change signal CH is not detected in step S42 (step S43), the touch controller 31 executes the detection operation of the downlink signal DS while maintaining the master mode, determines the transmission / reception schedule again by the same process as when entering the master mode, returns to step S40, and transmits the uplink signal US. Further, when the state where the downlink signal DS is not detected in step S42 continues for a predetermined time or longer (step S44), the touch controller 31 returns to the discovery mode and executes the process from step S30.

[0042] On the other hand, when the reference change signal CH is detected in step S42 (step S45), the touch controller 31 enters the slave mode, obtains the transmission / reception schedule based on the reference change signal CH, and then continues to perform the detection operation of the downlink signal DS (step S50). In this case, the touch controller 31 obtains the frame position based on the reception timing of the reference change signal CH. Therefore, for the touch controller 31 that has entered the slave mode, the reference change signal CH functions as a reference signal for notifying the frame position. On the other hand, for information other than the frame position (information on the frame structure and time slot information) among the information constituting the transmission / reception schedule, the touch controller 31 uses the one of the previously determined transmission / reception schedules. In other words, the touch controller 31 that has entered the slave mode passes only the right to determine the frame position among various information constituting the transmission / reception schedule to the active pen 2.

[0043] When the touch controller 31 does not detect the downlink signal DS for a predetermined time or more in step S50 (step S51), it returns to the discovery mode and executes the process from step S30. Further, when the reference change signal CH is detected in step S50 (step S52), the touch controller 31 acquires a new transmission / reception schedule based on the reference change signal CH, then executes the detection operation of the downlink signal DS, and then transmits the uplink signal US (step S53). After the transmission of the uplink signal US is completed (step S54), it returns to step S50 to detect the reference change signal CH and the downlink signal DS.

[0044] When the touch controller 31 does not detect the reference change signal CH in step S50 (step S55), it returns to the master mode and executes the detection operation of the downlink signal DS (step S42). The touch controller 31 that has returned to the master mode in this way determines a new transmission / reception schedule by the same process as when entering the master mode, and then transmits the uplink signal US in step S40.

[0045] As described above, according to the position detection system 1 according to the present embodiment, when the active pen 2 fails to receive the uplink signal US, the active pen 2 can be made the master of frame synchronization. Therefore, it is possible to avoid a disconnection when the active pen 2 fails to receive the uplink signal US. Hereinafter, the operations of the active pen 2 and the touch controller 31 for avoiding such a disconnection will be described in more detail with reference to FIGS. 4 to 9.

[0046] Figures 4 and 5 are diagrams showing the time variation of signals transmitted and received between the active pen 2 (integrated circuit 25 thereof) and the touch controller 31. Figure 4 shows a scene where the active pen 2 transitions from the slave mode to the master mode, and Figure 5 shows a scene where the active pen 2 transitions from the master mode to the slave mode. Further, Figures 4 and 5 show a frame F and m + 1 time slots TS (TS0 to TSm) set within the frame F. The time slot TS0 is the head slot described above. Furthermore, the illustrated "R" indicates the reception period of the signal, "T" indicates the detection period of the passive pointer, and "UpIntv" indicates the time length of the frame F. Note that in Figures 4 and 5, only the periods within the above-described blank time are shown, and the drawing is omitted for the time when the pixels are driven by the display 32.

[0047] First, referring to Figure 4, the active pen 2 has successfully received the uplink signal US transmitted by the touch controller 31 at the head (time t1) of the n-th frame Fn. In this case, the active pen 2 maintains the slave mode, obtains a transmission / reception schedule based on the received uplink signal US, and then transmits a downlink signal DS using the time slots TS1 to TSm. In this case, the active pen 2 does not transmit a signal in the time slot TS0.

[0048] Thereafter, the active pen 2 according to the example of Figure 4 has failed to receive the uplink signal US transmitted by the touch controller 31 at the head (time t2) of the (n + 1)-th frame Fn+1. In this case, the active pen 2 continues the detection operation of the uplink signal US until the time t3 when the time obtained by adding a predetermined time ΔT to the time length UpIntv of the frame F from the end of the reception of the previous uplink signal US has elapsed, and then enters the master mode. Note that if the pen pressure value at this point is 0, that is, if it is in the hover state, the active pen 2 may continue the slave mode. This point will be described in more detail later with reference to Figures 6 and 7.

[0049] The active pen 2 that has entered the master mode determines the transmission / reception schedule for the (n + 1)-th frame Fn+1 by diverting the transmission / reception schedule obtained in the n-th frame Fn, and then uses the time slot TS0 to transmit the reference change signal CH and uses the time slots TS1 to TSm to transmit the downlink signal DS respectively. The touch controller 31 that has received the reference change signal CH at time t4 enters the slave mode and starts operations based on the reception timing of the reference change signal CH.

[0050] Next, referring to FIG. 5, the active pen 2 that has successfully received the uplink signal US transmitted by the touch controller 31 at the start (time t5) of the (n + k)-th frame Fn+k enters the slave mode. As a result, the active pen 2 stops transmitting the reference change signal CH in the time slot TS0 of the frame Fn+k, while continuing to transmit the downlink signal DS in the time slots TS1 to TSm of the frame Fn+k.

[0051] The touch controller 31 that has detected that the active pen 2 has not transmitted the reference change signal CH in the time slot TS0 enters the master mode. Then, in the time slots TS1 to TSm of the frame Fn+k, after receiving the downlink signal DS using the transmission / reception schedule obtained based on the reference change signal CH, the touch controller 31 determines the transmission / reception schedule based on the blank time information supplied from the host processor 33, and transmits the uplink signal US at the start of the frame Fn+k+1 according to the determined transmission / reception schedule. After this, the active pen 2 starts operations based on the reception timing of this uplink signal US.

[0052] FIG. 6 and FIG. 7 are flowcharts showing the processes executed by the integrated circuit 25 of the active pen 2. As shown in the figures, the integrated circuit 25 first enters the discovery mode (step S100) and executes a detection operation of the uplink signal US (step S101). Then, it is determined whether the uplink signal US has been received (step S102). If it is determined that the signal has not been received, the process returns to step S101 to continue the discovery mode process.

[0053] On the other hand, if it is determined in step S102 that the signal has been received, the integrated circuit 25 enters the slave mode (step S103) and acquires a transmission / reception schedule based on the received uplink signal US (step S104). Then, it transmits the downlink signal DS using the time slots TS1 to TSm (step S105) and executes a detection operation of the uplink signal US at the start of the next frame (step S106). In this case, the integrated circuit 25 does not transmit a signal in the time slot TS0.

[0054] Next, the integrated circuit 25 determines whether it has received the uplink signal US in step S106 (step S107). If it determines that it has received the signal, it returns to step S104 and continues the processing in the slave mode. On the other hand, if it determines that it has not received the signal, the integrated circuit 25 first determines whether a predetermined time has elapsed since it last received the uplink signal US (step S108). If it determines that the time has elapsed, it returns to step S100 and starts the processing in the discovery mode. On the other hand, the integrated circuit 25 that determines that the time has not elapsed refers to the latest pen pressure value supplied from the pressure sensor 22 shown in FIG. 1 and determines whether the active pen 2 is in contact (a state where the pen tip is in contact with the touch surface 3a) (step S109). Specifically, if the pen pressure value is greater than 0, it is determined that the pen is in contact, and if not, it is determined that the pen is hovering (a state where the pen tip is not in contact with the touch surface 3a). If it determines that the pen is hovering, after determining the transmission / reception schedule based on the latest acquired transmission / reception schedule (step S110), the integrated circuit 25 returns to step S106 and continues the processing in the slave mode. On the other hand, if it determines that the pen is in contact, it transitions to step S120 shown in FIG. 7 and starts the processing in the master mode. In this way, the integrated circuit 25 is shifted to the master mode only when the pen is in contact, and the processing in the slave mode is continued for the integrated circuit 25 when the pen is hovering because there is no input of a stroke in the first place when the pen is hovering and there is no risk of a disconnection.

[0055] Specifically explaining the processing after step S120, as shown in FIG. 7, the integrated circuit 25 first enters the master mode (step S120) and, similar to step S110, determines the transmission / reception schedule based on the latest transmission / reception schedule (step S121). Next, the integrated circuit 25 transmits the reference change signal CH using the time slot TS0 (step S122), transmits the downlink signal DS using the time slots TS1 to TSm (step S123), and executes the detection operation of the uplink signal US at the start of the next frame (step S124).

[0056] Subsequently, the integrated circuit 25 determines whether it has received the uplink signal US in step S16 (step S125). If it determines that it has received the signal, it returns to step S103 and starts the processing in slave mode. On the other hand, if it determines that it has not received the signal, the integrated circuit 25 first determines whether a predetermined time has elapsed since it last received the uplink signal US (step S126). If it determines that the time has elapsed, it returns to step S100 shown in FIG. 6 and starts the processing in discovery mode. On the other hand, the integrated circuit 25 that determines that the time has not elapsed refers to the latest pen pressure value supplied from the pressure sensor 22 shown in FIG. 1 and further determines whether the active pen 2 is in contact (step S127). The specific method of this determination may be the same as that in step S109. As a result of the determination, the integrated circuit 25 that determines that it is in contact returns to step S121 and continues the processing in master mode. On the other hand, the integrated circuit 25 that determines that it is hovering enters the slave mode (step S128). After determining the transmission / reception schedule based on the latest transmission / reception schedule in the same manner as in step S110 (step S129), it returns to step S106 shown in FIG. 6. Note that, even though it has entered the slave mode, in step S129, the transmission / reception schedule is determined based on the latest transmission / reception schedule because the current transmission / reception schedule is required for the active pen 2 to receive the next uplink signal US.

[0057] FIGS. 8 and 9 are flowcharts showing the processing executed by the touch controller 31. As shown in the figures, the touch controller 31 first enters the discovery mode (step S130). After determining the transmission / reception schedule based on the blank time information supplied from the host processor 33 (step S131), it executes the transmission of the uplink signal US at the head of the frame (step S132). Further, it executes the detection operation of the downlink signal DS in the time slots TS1 to TSm (step S133). At this time, it is not necessary to perform the detection operation of the reference change signal CH in the time slot TS0, but it may be performed.

[0058] Next, the touch controller 31 determines whether or not it has received the downlink signal DS in step S133 (step S134). If it determines that it has not received the signal, it returns to step S131 to continue the discovery mode process. On the other hand, if it determines that it has received the signal, it enters the master mode (step S135), derives the position of the active pen 2 based on the received downlink signal DS, and acquires the data transmitted by the active pen 2 (step S136), and outputs the data to the host processor 33 (step S137). Subsequently, after the touch controller 31 determines the transmission / reception schedule again by the same process as in step S131 (step S138), it transmits the uplink signal US at the start of the next frame (step S139), and performs the detection operation of the reference change signal CH in the time slot TS0 (step S140).

[0059] Then, the touch controller 31 determines whether or not it has received the reference change signal CH in step S140 (step S141). If it determines that it has received the signal, it transitions to step S150 shown in FIG. 9 to start the slave mode process. On the other hand, the touch controller 31 that determines that it has not received the signal performs the detection operation of the downlink signal DS in the time slots TS1 to TSm (step S142), and determines whether or not it has received the signal (step S143). As a result, the touch controller 31 that determines that it has received the signal returns to step S136 to continue the master mode process. On the other hand, the touch controller 31 that determines that it has not received the signal determines whether or not a predetermined time has elapsed since it last received the downlink signal DS (step S144). As a result, if it determines that the time has elapsed, it returns to step S130 to start the discovery mode process. On the other hand, the touch controller 31 that determines that the time has not elapsed returns to step S138 to continue the master mode process.

[0060] Specifically describing the processing after step S150, as shown in FIG. 9, the touch controller 31 first enters the slave mode (step S150) and acquires a transmission / reception schedule based on the reference change signal CH (step S151). That is, the reception start timing of the reference change signal CH is regarded as the start timing of the time slot TS0, and the frame position is acquired. Next, the touch controller 31 executes a detection operation of the downlink signal DS in the time slots TS1 to TSm (step S152) and determines whether it has been received (step S153). As a result, if it is determined that it has been received, the touch controller 31 derives the position of the active pen 2 based on the received downlink signal DS and acquires the data transmitted by the active pen 2 (step S154), and outputs it to the host processor 33 (step S155). Subsequently, the touch controller 31 transmits an uplink signal US at the head of the next frame (step S156) and executes a detection operation of the reference change signal CH in the time slot TS0 (step S157). Then, it is determined whether the reference change signal CH has been received (step S158).

[0061] The touch controller 31 that determines that it has been received in step S158 returns to step S151 to continue the processing in the slave mode. On the other hand, the touch controller 31 that determines that it has not been received enters the master mode (step S159), determines a transmission / reception schedule based on the blank time information supplied from the host processor 33 (step S160), and then returns to step S142 shown in FIG. 8. The transmission / reception schedule determined in step S160 is applied from the transmission of the uplink signal US (step S139) that is first executed thereafter. The reason for not applying the transmission / reception schedule determined in step S160 to step S142 immediately after the transition from step S160 is that at this stage, the downlink signal DS is being transmitted according to the transmission / reception schedule determined by the active pen 2.

[0062] The touch controller 31 that has determined that it has not received in step S153 determines whether or not a predetermined time has elapsed since it last received the downlink signal DS (step S161). As a result, if it is determined that the time has elapsed, the process returns to step S130 shown in FIG. 8 to start the discovery mode process. On the other hand, the touch controller 31 that has determined that the time has not elapsed returns to step S156 to continue the slave mode process.

[0063] As described above, according to the position detection system 1 according to the present embodiment, when the active pen 2 fails to receive the uplink signal US, the active pen 2 can be made the master of frame synchronization. Therefore, it is possible to avoid a disconnection when the active pen 2 fails to receive the uplink signal US.

[0064] Also, according to the position detection system 1 according to the present embodiment, the active pen 2 can be made the master of frame synchronization only when the active pen 2 is in contact. Therefore, it is possible to make the active pen 2 the master of frame synchronization only when it is necessary to prevent disconnection.

[0065] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the gist thereof.

[0066] For example, in the above embodiment, the case where the touch controller 31 detects the position of the active pen 2 by the active electrostatic method has been described as an example. However, the present invention is widely applicable when the touch controller 31 and the active pen 2 communicate bidirectionally. For example, the present invention is also applicable when the touch controller 31 detects the position of the active pen 2 by the electromagnetic induction method.

[0067] In the above embodiment, an example in which the first slot in the frame is reserved for transmitting the reference change signal CH has been described. However, it is only necessary that the reference change signal CH can be transmitted from the active pen 2 to the touch controller 31 in a timely manner, and the transmission method of the reference change signal CH is not limited to that described in the above embodiment. For example, the active pen 2 may transmit the reference change signal CH using a time slot other than the first slot, or may transmit the reference change signal CH simultaneously with the downlink signal DS by using a different frequency, phase, code, etc. from the downlink signal DS, or may transmit the reference change signal CH using an entirely different communication method such as short-range wireless communication represented by Bluetooth (registered trademark).

[0068] In the above embodiment, an example in which it is indicated whether the active pen 2 becomes the master of synchronization based on the presence or absence of the reference change signal CH has been described. However, information indicating whether the active pen 2 becomes the master of synchronization can be notified to the touch controller 31 by any method. For example, the active pen 2 can notify the touch controller 31 whether it becomes the master of synchronization by transmitting different bit values, different frequencies, different phases, or different codes when it becomes the master of synchronization and when it does not. Among these, when using "different bit values", the reference change signal CH may be transmitted by one bit in the data signal constituting the downlink signal DS.

[0069] In the above embodiment, an example in which the reference change signal CH also serves as a reference signal for synchronizing the frame position has been described. However, these may be different signals. For example, the touch controller 31 that has entered the slave mode may acquire the frame position based on the reception timing of the downlink signal DS received in the time slot TS1.

Explanation of Signs

[0070] 1 Position detection system 2 Active pen 3 Electronic device 3a Touch surface 20 Core 21 Pen tip electrode 22 Pressure sensor 23 Side switch 24 Battery 25 Integrated circuit 30 Sensor 31 Touch controller 32 Display 33 Host processor CH Reference change signal DS Downlink signal F Frame TS Time slot US Uplink signal

Claims

1. A system including a pen and a touch controller, wherein the pen and the touch controller are configured to transmit and receive signals to and from each other using a frame including a plurality of pen detection periods that are temporally separated, and the pen and the touch controller are each configured to be able to transmit and detect a reference signal for synchronizing frame positions, and when the reference signal is detected, to acquire the frame position based on the reference signal and operate according to the acquired frame position, wherein the pen is configured to transmit a reference change signal indicating that it becomes the master of the synchronization when changing the master of the synchronization, a system.

2. When the touch controller receives the reference change signal, the touch controller acquires the frame position according to the reference signal transmitted by the pen, The system according to claim 1.

3. The reference change signal is a signal that notifies that it becomes the master of the synchronization by any one of different bit values, different frequencies, different phases, and different codes, and is repeatedly transmitted, The system according to claim 2.

4. The pen is configured to transmit the reference change signal to the touch controller when a predetermined condition is satisfied, The system according to claim 2.

5. The predetermined condition is a case where, as a result of attempting to receive the next uplink signal according to the frame position acquired based on the uplink signal received by the pen from the touch controller in the past, the uplink signal is not received, The system according to claim 4.

6. The predetermined condition is a case where, as a result of attempting to receive the next uplink signal according to the frame position acquired based on the uplink signal received by the pen from the touch controller in the past, the uplink signal is not received and the pen is in contact, The system according to claim 4.

7. The pen transmits the reference change signal while the master of the synchronization is the touch controller, and transmits the reference signal at least once simultaneously with or after the transmission of the reference change signal, The system according to claim 2.

8. The touch controller is configured to transmit a reference change signal indicating that it becomes the master of the synchronization, The system according to claim 1.

9. A method performed by a pen in a system including the pen and a touch controller, the method comprising: performing a detection operation of a next reference signal according to a frame position obtained based on a reference signal transmitted by the touch controller; determining whether the reference signal is received by the detection operation; when it is determined that the reference signal is not received by the detection operation, transmitting a reference change signal indicating that itself becomes a master of synchronization of the frame position; A method including the above steps.

10. The reference signal is an uplink signal transmitted by the touch controller, The method according to claim 9.

11. further comprising determining whether the pen is in contact based on a pen pressure value indicating a pressure applied to a pen tip of the pen, The transmitting step includes transmitting the reference change signal when it is determined that the reference signal is not received by the detection operation and it is determined that the pen is in contact. The method according to claim 9 or 10.

12. A pen having an integrated circuit and a pen tip electrode and communicating bidirectionally with a touch controller, the pen comprising: The integrated circuit: performing a detection operation of a next reference signal using the pen tip electrode according to a frame position obtained based on a reference signal transmitted by the touch controller; determining whether the reference signal is received by the detection operation; when it is determined that the reference signal is not received by the detection operation, transmitting a reference change signal indicating that itself becomes a master of synchronization of the frame position from the pen tip electrode; A pen.

13. A touch controller that derives a position of the pen by communicating bidirectionally with the pen via a sensor, the touch controller comprising: when receiving a reference change signal indicating that itself becomes a master of synchronization of a frame position from the pen, obtaining the frame position according to a reference signal for synchronizing the frame position transmitted by the pen; performing a detection operation of a downlink signal transmitted by the pen and transmitting an uplink signal to the pen based on the obtained frame position; A touch controller.

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