Pen and system including pen and touch controller

Abstract

To avoid broken lines when a pen fails to receive an uplink signal.SOLUTION: A pen according to the present invention has an integrated circuit and a pen tip electrode, and performs bidirectional communication with a touch controller. The integrated circuit is configured to use the pen tip electrode to perform a detection operation for a next reference signal according to a frame position acquired based on a reference signal transmitted by the touch controller, determine whether or not the reference signal has been received by the detection operation, and, if it is determined that the reference signal has not been received by the detection operation, transmit a reference change signal indicating that the integrated circuit itself serves as a master for synchronization of the frame position by short-range wireless communication.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Among position detection systems that perform one-way communication from a pen to a touch controller, there is one that synchronizes the touch controller with the pen using a signal transmitted by the pen (hereinafter referred to as a "pen signal"). Patent Document 1 discloses an example of such a position detection system.

[0003] In the above-described one-way communication position detection system, the pen may transmit unnecessary pen signals, resulting in unnecessary power consumption. For example, if a touch controller performs pen detection in a time-sharing manner with the detection of finger touches and the driving of pixels included in a display, pen signals transmitted outside the period in which the touch controller is performing pen detection will not be received by the touch controller, even if transmitted by the pen. Therefore, the pen signals are unnecessary. In recent years, position detection systems that perform bidirectional communication between a pen and a touch controller have emerged. Bidirectional communication allows the pen to transmit pen signals only when the touch controller needs them, thereby avoiding the above-described unnecessary power consumption. Patent documents 2 and 3 disclose examples of position detection systems that perform bidirectional communication between a pen and a touch controller. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] U.S. Patent Publication No. 2010 / 0155153 [Patent Document 2] U.S. Patent No. 9,977,519 [Patent Document 3] International Publication No. 2016 / 139861 Summary of the Invention [Problem to be solved by the invention]

[0005] In a position detection system that performs bidirectional communication between a pen and a touch controller, a frame including multiple time slots is used. The touch controller transmits an uplink signal at the beginning of each frame, and the pen transmits a pen signal using one or more of the time slots. The frame structure and the time slots used by the pen are predetermined by a protocol. The uplink signal serves to indicate the time position of the frame (hereinafter referred to as the "frame position"). The pen is configured to obtain the frame position based on the reception timing of the uplink signal and to determine the transmission timing of the pen signal and the reception timing of the next uplink signal according to the obtained frame position.

[0006] However, the pen may fail to receive an uplink signal due to the influence of external noise, etc. If this happens, the pen will be unable to acquire the frame position and will be unable to transmit a pen signal, resulting in the drawing of the stroke being input stopping, or a so-called broken line. Therefore, the inventors of the present application are considering configuring a pen so that it can transmit a pen signal even if it fails to receive an uplink signal by using the frame position acquired based on the most recent uplink signal that was received for a frame for which an uplink signal was not received.

[0007] However, since the clock signal frequencies of the pen and the touch controller are usually not perfectly matched, if the pen transmits a pen signal by reusing the frame position as described above, the timing will gradually become out of sync, making it difficult for the touch controller to receive the signal. Therefore, further technology is needed to avoid interrupting stroke drawing even if the pen fails to receive an uplink signal.

[0008] Therefore, 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 line disconnection when the pen fails to receive an uplink signal. [Means for solving the problem]

[0009] The 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 each other using frames including a plurality of pen detection periods spaced apart in time, the pen and the touch controller are each configured to transmit and detect a reference signal for synchronizing a frame position, and when the reference signal is detected, the pen and the touch controller obtain the frame position based on the reference signal and operate according to the obtained frame position, and when the pen changes the master of the synchronization, the pen is configured to transmit a reference change signal indicating that it will become the master of the synchronization.

[0010] The method according to the present invention is a method executed by the pen in a system including the pen and a touch controller, and includes the steps of: performing a detection operation for a next reference signal according to a frame position obtained based on a reference signal transmitted by the touch controller; determining whether or not the reference signal has been received by the detection operation; and, if it is determined that the reference signal has not been received by the detection operation, transmitting a reference change signal indicating that the touch controller itself will become a master for synchronization of the frame position.

[0011] The pen according to the present invention has an integrated circuit and a pen tip electrode, and communicates bidirectionally with a touch controller. The integrated circuit uses the pen tip electrode to perform a detection operation for the next reference signal according to a frame position acquired based on a reference signal transmitted by the touch controller, determines whether or not the reference signal has been received by the detection operation, and, if it determines that the reference signal has not been received by the detection operation, transmits a reference change signal from the pen tip electrode indicating that the integrated circuit will become the master for synchronizing the frame position.

[0012] The touch controller of the present invention is a touch controller that derives the position of a pen by communicating bidirectionally with the pen via a sensor, and when it receives a reference change signal from the pen indicating that it will become the master for frame position synchronization, it acquires the frame position in accordance with a reference signal for synchronizing the frame position transmitted by the pen, and based on the acquired frame position, it detects a downlink signal transmitted by the pen and transmits an uplink signal to the pen. [Effects of the Invention]

[0013] The present invention allows the pen to be the master of frame synchronization when necessary, thus avoiding broken lines when the pen fails to receive the uplink signal. [Brief explanation of the drawings]

[0014] [Figure 1] 1 is a diagram showing a configuration of a position detection system 1 according to an embodiment of the present invention. [Figure 2] 10 is a state transition diagram of the integrated circuit 25 of the active pen 2. FIG. [Figure 3] 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. FIG. [Figure 4] 10 is a diagram showing time variations in signals transmitted and received between the active pen 2 and the touch controller 31. FIG. [Figure 5]10 is a diagram showing time variations in signals transmitted and received between the active pen 2 and the touch controller 31. FIG. [Figure 6] 10 is a process flow diagram showing the process executed by the integrated circuit 25 of the active pen 2. FIG. [Figure 7] 10 is a process flow diagram showing the process executed by the integrated circuit 25 of the active pen 2. FIG. [Figure 8] 10 is a process flow diagram showing the process executed by the touch controller 31. FIG. [Figure 9] 10 is a process flow diagram showing the process executed by the touch controller 31. FIG. DETAILED DESCRIPTION OF THE INVENTION

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

[0016] 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 is configured to include an active pen 2 and an electronic device 3 which is a position detection device that detects 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. The electronic device 3 includes a sensor 30 arranged directly below the touch surface 3a, a touch controller 31 connected to the sensor 30, a display 32 arranged superimposed on the sensor 30, and a host processor 33 that controls each part of the electronic device 3 including these components.

[0018] The host processor 33 is the central processing unit of the electronic device 3, and is configured to read and execute various programs from a memory (not shown). The programs executed in this manner include the operating system of the electronic device 3 and various applications, including a drawing application. Of these, the drawing application is a program for executing processes of generating digital ink based on the position and data acquired by the touch controller 31 and storing it in memory within the electronic device 3, and rendering the generated digital ink, generating a video signal showing 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 configured, for example, by 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 within the touch surface 3a. The plurality of sensor electrodes include a plurality of X electrodes each extending along the Y direction within the touch surface 3a and juxtaposed at equal intervals along the X direction perpendicular to the Y direction within 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] Some of the multiple sensor electrodes constituting the sensor 30 can also be used as a common electrode of the display 32 (an electrode for supplying a ground potential to each pixel in common). When this common use is performed, the electronic device 3 constitutes a so-called "in-cell type" position detection device. On the other hand, when this common use is not performed, the electronic device 3 constitutes a so-called "on-cell type" or "out-cell type" position detection device. The present invention can be suitably applied to either electronic device 3, but the following description will continue assuming that the electronic device 3 is an in-cell type position detection device.

[0021] The touch controller 31 is an integrated circuit that has the function of detecting the positions of the active pen 2 and the passive pointer (e.g., a human finger) within the touch surface 3a. Specifically, it is configured to detect the position of the active pen 2 by an active electrostatic method and to detect the position of the passive pointer by a capacitive method.

[0022] To explain in more detail about position detection of the active pen 2 using the active electrostatic method, the touch controller 31 derives the position of the active pen 2 within the touch surface 3a and performs processing to acquire 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 will be referred to as the "uplink signal US," and the signal transmitted from the active pen 2 to the touch controller 31 will be referred to as the "downlink signal DS."

[0023] The downlink signal DS is one type of the pen signal described above. In this embodiment, the pen signal also includes a "reference change signal CH" in addition to the "downlink signal DS," but this will be described later. The touch controller 31 transmits the uplink signal US by changing the potential of each sensor electrode that constitutes the sensor 30, and receives the downlink signal DS and the reference change signal CH by detecting changes in the potential of each sensor electrode that constitutes the sensor 30.

[0024] The touch controller 31 is configured to set a frame based on information about a time when pixels are not driven by the display 32 (hereinafter referred to as "blank time"), and to arrange within the frame a plurality of time slots (a plurality of pen detection periods spaced apart in time), each of which is a period during which the touch controller 31 detects a pen signal, and a plurality of passive pointer detection periods, each of which is a period during which the touch controller 31 detects a passive pointer. The touch controller 31 receives a pen signal in each time slot, and performs processing to detect a passive pointer in each passive pointer detection period.

[0025] The host processor 33 notifies the touch controller 31 of the blank time information. The touch controller 31 determines the frame position based on the blank time information notified by the host processor 33, and arranges the above-mentioned multiple time slots and multiple passive pointer detection periods within the frame. Typically, each frame is configured to include multiple blank times, and the multiple time slots and multiple passive pointer detection periods are arranged in a dispersed 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 include a plurality of patterns that indicate different temporal arrangements of time slots and passive pointer detection periods within a frame. The touch controller 31 is configured to arrange a plurality of time slots and a plurality of passive pointer detection periods within a frame by selecting one of the plurality of patterns based on blank time information notified from the host processor 33. The touch controller 31 also performs processing to notify the active pen 2 of the selected pattern and information indicating the time slot that the active pen 2 should actually use to transmit a pen signal by using a command in the uplink signal US.

[0027] The uplink signal US functions as a reference signal that notifies the active pen 2 of the above-mentioned frame position from the touch controller 31, and also serves to transmit commands from the touch controller 31 to control the active pen 2. The touch controller 31 is configured to transmit the uplink signal US at the beginning of a frame, and the active pen 2 is configured to acquire the frame position based on the reception timing of the uplink signal US. The active pen 2 is also configured to acquire, from a command included in the uplink signal US, the frame structure (such as the temporal arrangement of multiple time slots) and information indicating the time slots that the active pen 2 should actually use to transmit a pen signal. Hereinafter, the frame position, frame structure, and information indicating the time slots may be collectively referred to as the "transmission / reception schedule."

[0028] The downlink signal DS is a signal that includes a position signal, which is an unmodulated carrier wave signal, and a data signal, which is a carrier wave signal modulated with various data such as pen pressure values ​​and switch information, which will be described later. The active pen 2 is configured to transmit the downlink signal DS in accordance with a 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 strength of the position signal at each of the multiple sensor electrodes that make up the sensor 30, and acquires the data transmitted by the active pen 2 by receiving and demodulating the data signal using the sensor electrode that is closest to the derived position among the multiple sensor electrodes.

[0029] 1, the active pen 2 is configured to have 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 that forms the pen shaft of the active pen 2. The tip of the core body 20 forms the pen tip of the active pen 2, and the end abuts against 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 writing pressure value. The side switch 23 is a push-button 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 operating 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, and 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, and transmits pen signals (specifically, the above-mentioned downlink signal DS and reference change signal CH) by applying a change to the potential of the pen tip electrode 21.

[0032] 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 discovery mode, slave mode, and master mode. The initial state is discovery mode, and the integrated circuit 25 that has entered the discovery mode performs an operation of detecting the uplink signal US continuously or intermittently (step S1).

[0033] If an uplink signal US is detected as a result of the detection operation in step S1 (step S2), the integrated circuit 25 enters slave mode and acquires the above-mentioned transmission / reception schedule based on the received uplink signal US. Subsequently, the integrated circuit 25 transmits a downlink signal DS in accordance with the acquired transmission / reception schedule (step S10). Furthermore, if the acquired transmission / reception schedule indicates the arrival of the frame end timing (step S11), the integrated circuit 25 performs an operation to detect the next uplink signal US (step S12). If an uplink signal US is detected as a result (step S13), the integrated circuit 25 acquires a new transmission / reception schedule based on the uplink signal US and repeats the process of step S10.

[0034] On the other hand, if the uplink signal US is not detected as a result of the detection operation in step S12, the integrated circuit 25 enters the master mode (step S14). The integrated circuit 25 that has entered the master mode reuses the most recent transmission and reception schedule that it has acquired for 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 and reception schedule for the current frame by shifting the most recent transmission and reception schedule that it has acquired backward by the time length UpIntv of the frame.

[0035] The transmission / reception schedule acquired by the integrated circuit 25 in this way may differ 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 will become the master of synchronization (frame synchronization) in the first time slot of the current frame (hereinafter referred to as the "first slot") (step S20). In this embodiment, the first 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 will set the first slot to mute (a state in which no signal is transmitted).

[0036] The integrated circuit 25 then transmits a downlink signal DS in accordance with the acquired transmission / reception schedule (step S21). If the acquired transmission / reception schedule indicates the end of the frame (step S22), it performs a detection operation for the next uplink signal US (step S23). If the uplink signal US is not detected (step S24), the integrated circuit 25 determines whether a predetermined time has elapsed since the last detection of the uplink signal US. If it determines that the predetermined time has elapsed, it returns to the discovery mode and executes the process from step S1 (step S24). On the other hand, if it determines that the predetermined time has not elapsed, it repeats the process from step S20 (step S25). In this case, the integrated circuit 25 is configured to acquire a transmission / reception schedule for the current frame based on the most recently acquired transmission / reception schedule, as in the case of entering the master mode.

[0037] The integrated circuit 25 that detected the uplink signal US in step S23 returns to slave mode and executes the process from step S10 (step S26). That is, the uplink signal US transmitted by the touch controller 31 functions as a reference change signal indicating that the touch controller 31 will become the synchronization master, and the integrated circuit 25 that receives the uplink signal US as this reference change signal ceases to be the synchronization master and returns to slave mode. In this case, the integrated circuit 25 acquires a transmission and reception schedule for the current frame based on the newly received uplink signal US.

[0038] 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 diagram, the touch controller 31 is also configured to operate in any one of discovery mode, slave mode, and master mode. The initial state is discovery mode, and the touch controller 31 entered in discovery mode determines a transmission / reception schedule based on blank time information supplied from the host processor 33, and then transmits an uplink signal US at the beginning of a frame (step S30). After completing transmission of the uplink signal US (step S31), the touch controller 31 performs a detection operation for a downlink signal DS in each time slot (step S32). Note that the touch controller 31 entered in discovery mode does not need to perform a detection operation for a 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 new transmission / reception schedule and returns to step S30 to repeat 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 the time length UpIntv of the frame (see FIGS. 4 and 5), or may determine the new transmission / reception schedule based on blank time information newly supplied or previously supplied from the host processor 33.

[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 to the active pen 2 that transmitted the downlink signal DS as the communication partner (step S40), and after the transmission is completed (step S41), performs a detection operation for the reference change signal CH and the downlink signal DS (step S42).

[0041] If the reference change signal CH is not detected in step S42 (step S43), the touch controller 31 performs the detection operation of the downlink signal DS while maintaining the master mode, and determines the transmission and reception schedule again by the same processing as when entering the master mode, and returns to step S40 to transmit the uplink signal US. Also, if the state in which the downlink signal DS is not detected in step S42 continues for a predetermined time or more (step S44), the touch controller 31 returns to the discovery mode and performs the processing from step S30.

[0042] On the other hand, if the reference change signal CH is detected in step S42 (step S45), the touch controller 31 enters slave mode, acquires a transmission / reception schedule based on the reference change signal CH, and then continues detecting the downlink signal DS (step S50). In this case, the touch controller 31 acquires the frame position based on the reception timing of the reference change signal CH. Therefore, for the touch controller 31 that has entered slave mode, the reference change signal CH functions as a reference signal that notifies the frame position. On the other hand, the touch controller 31 reuses the information other than the frame position (frame structure and time slot information) that constitutes the transmission / reception schedule that was previously determined. In other words, the touch controller 31 that has entered slave mode only transfers to the active pen 2 the right to determine the frame position out of the various pieces of information that constitute the transmission / reception schedule.

[0043] If the touch controller 31 continues not to detect the downlink signal DS for a predetermined time or more in step S50 (step S51), the touch controller 31 returns to discovery mode and executes the processing from step S30. Also, if 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 a detection operation for the downlink signal DS, and then transmits an uplink signal US (step S53). After the transmission of the uplink signal US is completed (step S54), the touch controller 31 returns to step S50 and executes the detection operation for the reference change signal CH and the downlink signal DS.

[0044] If the reference change signal CH is not detected in step S50 (step S55), the touch controller 31 returns to the master mode and executes the detection operation of the downlink signal DS (step S42). Having returned to the master mode, the touch controller 31 determines a new transmission and reception schedule by the same process as when it entered the master mode, and then transmits the uplink signal US in step S40.

[0045] As described above, according to the position detection system 1 of this embodiment, if the active pen 2 fails to receive the uplink signal US, the active pen 2 can become the master of frame synchronization. This makes it possible to avoid line disconnection when the active pen 2 fails to receive the uplink signal US. The operation of the active pen 2 and touch controller 31 to avoid such line disconnection will be described in more detail below with reference to FIGS. 4 to 9.

[0046] 4 and 5 are diagrams showing changes over time in signals transmitted and received between the active pen 2 (its integrated circuit 25) and the touch controller 31. FIG. 4 shows a scene in which the active pen 2 transitions from slave mode to master mode, and FIG. 5 shows a scene in which the active pen 2 transitions from master mode to slave mode. Also, FIGS. 4 and 5 show a frame F and m+1 time slots TS (TS0 to TSm) set within frame F. Time slot TS0 is the first slot mentioned above. Furthermore, "R" shown in the figures indicates a signal reception period, "T" indicates a passive pointer detection period, and "UpIntv" indicates the time length of frame F. Note that FIGS. 4 and 5 only show the period within the blank time mentioned above, and do not depict the time during which pixels are driven by the display 32.

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

[0048] Thereafter, the active pen 2 in the example of FIG. 4 fails to receive the uplink signal US transmitted by the touch controller 31 at the beginning of the (n+1)th frame Fn+1 (time t2). In this case, the active pen 2 continues detecting the uplink signal US until time t3, when a time equal to the duration UpIntv of frame F plus a predetermined time ΔT has elapsed since the end of reception of the previous uplink signal US, and then enters master mode. Note that if the pen pressure value at this point is 0, i.e., if the active pen 2 is in a hover state, it may remain in slave mode. This point will be explained in more detail later with reference to FIGS. 6 and 7.

[0049] The active pen 2 that has entered the master mode determines the transmission and reception schedule for the (n+1)th frame Fn+1 by reusing the transmission and reception schedule acquired in the nth frame Fn, and then transmits the reference change signal CH using time slot TS0 and the downlink signal DS using time slots TS1 to TSm. Upon receiving the reference change signal CH at time t4, the touch controller 31 enters the slave mode and starts operating based on the timing of receiving the reference change signal CH.

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

[0051] The touch controller 31, having detected that the active pen 2 did not transmit the reference change signal CH in time slot TS0, enters master mode. Then, in time slots TS1 to TSm of frame Fn+k, it continues to receive the downlink signal DS using the transmission and reception schedule acquired based on the reference change signal CH, and then determines the transmission and reception schedule based on blank time information supplied from the host processor 33. It then transmits the uplink signal US at the beginning of frame Fn+k+1 in accordance with the determined transmission and reception schedule. After this, the active pen 2 starts operating based on the timing of receiving this uplink signal US.

[0052] 6 and 7 are process flow diagrams showing the processing executed by the integrated circuit 25 of the active pen 2. As shown in the figures, the integrated circuit 25 first enters discovery mode (step S100) and executes a detection operation for an uplink signal US (step S101). Then, it determines whether or not an uplink signal US has been received (step S102), and if it determines that an uplink signal US has not been received, it returns to step S101 and continues processing in discovery mode.

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

[0054] Next, the integrated circuit 25 determines whether or not an uplink signal US has been received in step S106 (step S107). If it is determined that an uplink signal US has been received, the process returns to step S104 and continues the slave mode process. On the other hand, if it is determined that an uplink signal US has not been received, the integrated circuit 25 first determines whether or not a predetermined time has elapsed since the last time the uplink signal US was received (step S108). If it is determined that the predetermined time has elapsed, the process returns to step S100 and starts the discovery mode process. On the other hand, if it determines that the predetermined time has not elapsed, the integrated circuit 25 references the latest writing pressure value supplied from the pressure sensor 22 shown in FIG. 1 and determines whether or not the active pen 2 is in contact (a state in which the pen tip is in contact with the touch surface 3 a) (step S109). Specifically, if the writing pressure value is greater than 0, the active pen 2 is determined to be in contact, and if not, the active pen 2 is determined to be in hover (a state in which the pen tip is not in contact with the touch surface 3 a). If it is determined that the active pen 2 is in hover, the integrated circuit 25 determines a transmission / reception schedule based on the latest transmission / reception schedule it has acquired (step S110), and then returns to step S106 and continues the slave mode process. On the other hand, if it is determined that contact is in progress, the process proceeds to step S120 shown in Fig. 7 and starts processing in the master mode. In this way, the integrated circuit 25 is transitioned to the master mode only when contact is in progress, and the integrated circuit 25 continues processing in the slave mode when hover is in progress because, when hover is in progress, no stroke is input in the first place, and there is no risk of line breakage.

[0055] 7, the integrated circuit 25 first enters the master mode (step S120) and, similar to step S110, determines a transmission / reception schedule based on the latest transmission / reception schedule (step S121). Next, the integrated circuit 25 transmits a reference change signal CH using time slot TS0 (step S122), transmits a downlink signal DS using time slots TS1 to TSm (step S123), and performs a detection operation for an uplink signal US at the beginning of the next frame (step S124).

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

[0057] 8 and 9 are processing flow diagrams showing the processing executed by the touch controller 31. As shown in the figures, the touch controller 31 first enters discovery mode (step S130), determines a transmission / reception schedule based on blank time information supplied from the host processor 33 (step S131), transmits an uplink signal US at the beginning of a frame (step S132), and then detects a downlink signal DS in time slots TS1 to TSm (step S133). At this time, it is not necessary to detect a reference change signal CH in time slot TS0, but it may be performed.

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

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

[0060] To explain the process from step S150 onward in detail, as shown in FIG. 9, the touch controller 31 first enters slave mode (step S150) and acquires a transmission / reception schedule based on the reference change signal CH (step S151). That is, the touch controller 31 regards the start timing of reception of the reference change signal CH as the start timing of time slot TS0 and acquires the frame position. Next, the touch controller 31 performs a detection operation for a downlink signal DS in time slots TS1 to TSm (step S152) and determines whether or not the downlink signal DS has been received (step S153). As a result, if it is determined that the downlink signal DS has been received, the touch controller 31 derives the position of the active pen 2 based on the received downlink signal DS and acquires data transmitted by the active pen 2 (step S154), and outputs the data to the host processor 33 (step S155). Next, the touch controller 31 transmits an uplink signal US at the beginning of the next frame (step S156) and performs a detection operation for the reference change signal CH in time slot TS0 (step S157). Then, it determines whether or not the reference change signal CH has been received (step S158).

[0061] If the touch controller 31 determines in step S158 that a signal has been received, it returns to step S151 and continues processing in the slave mode. On the other hand, if it determines that a signal has not been received, it 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 first transmission of the uplink signal US (step S139) that is executed thereafter. The transmission / reception schedule determined in step S160 is not applied to step S142 immediately after the transition from step S160 because, at this stage, the downlink signal DS is being transmitted according to the transmission / reception schedule determined by the active pen 2.

[0062] If the touch controller 31 determines in step S153 that a downlink signal DS has not been received, it determines whether or not a predetermined time has elapsed since the last time the downlink signal DS was received (step S161). If it determines that the predetermined time has elapsed, the process returns to step S130 shown in Fig. 8 and starts processing in the discovery mode. On the other hand, if the touch controller 31 determines that the predetermined time has not elapsed, the process returns to step S156 and continues processing in the slave mode.

[0063] As described above, according to the position detection system 1 of this embodiment, if the active pen 2 fails to receive the uplink signal US, the active pen 2 can become the master of frame synchronization. This makes it possible to avoid line disconnection when the active pen 2 fails to receive the uplink signal US.

[0064] Furthermore, according to the position detection system 1 of this embodiment, the active pen 2 can be made the master of frame synchronization only when the active pen 2 is in contact with the screen. Therefore, the active pen 2 can be made the master of frame synchronization only when it is necessary to prevent line breaks.

[0065] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that the present invention can be embodied in various forms without departing from the spirit of the present invention.

[0066] For example, in the above embodiment, an example has been described in which the touch controller 31 detects the position of the active pen 2 by an active electrostatic method, but the present invention is widely applicable to cases in which two-way communication is performed between the touch controller 31 and the active pen 2. For example, the present invention is also applicable to cases in which the touch controller 31 detects the position of the active pen 2 by an electromagnetic induction method.

[0067] Furthermore, in the above embodiment, an example has been described in which the first slot in a frame is reserved for transmitting the reference change signal CH, but the method of transmitting the reference change signal CH is not limited to that described in the above embodiment, as long as the reference change signal CH can be transmitted from the active pen 2 to the touch controller 31 in a timely manner. 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 frequency, phase, code, etc. different from those of the downlink signal DS, or may transmit the reference change signal CH using an entirely different communication method, such as short-range wireless communication typified by Bluetooth (registered trademark).

[0068] Furthermore, in the above embodiment, an example has been described in which the presence or absence of the reference change signal CH indicates whether the active pen 2 will be the synchronization master, but information indicating whether the active pen 2 will be the synchronization master 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 will be the synchronization master by transmitting a different bit value, a different frequency, a different phase, or a different code depending on whether it will be the synchronization master or not. When using a "different bit value" among these, the reference change signal CH may be transmitted by one bit in a data signal constituting the downlink signal DS.

[0069] In the above embodiment, the reference change signal CH also serves as a reference signal for synchronizing the frame position, but 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 time slot TS1. [Explanation of symbols]

[0070] 1. Position detection system 2 Active Pen 3 Electronic equipment 3a Touch Surface 20 core body 21 Pen tip electrode 22 Pressure Sensor 23 Side switch 24 Battery 25 Integrated Circuits 30 sensors 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 pen having an integrated circuit and a pen tip electrode, and communicating bidirectionally with a touch controller, The integrated circuit comprises: According to the frame position acquired based on the reference signal transmitted by the touch controller, a detection operation of the next reference signal is performed using the pen tip electrode; determining whether the reference signal is received by the detecting operation; When it is determined that the reference signal has not been received by the detection operation, the device transmits a reference change signal by short-range wireless communication, indicating that the device itself will become a master for synchronization of the frame position. pen.

2. The integrated circuit comprises: When it is determined that the reference signal has not been received by the detection operation performed while in contact, the reference change signal is transmitted, When it is determined that the reference signal has not been received by the detection operation performed during hovering, the reference change signal is not transmitted.

10. The pen of claim 1.

3. Further comprising a pressure sensor; The integrated circuit determines that the touch panel is in contact when the writing pressure value supplied from the pressure sensor is greater than a predetermined value, and determines that the touch panel is in hover when the writing pressure value is not greater than a predetermined value.

3. The pen of claim 2.

4. When the integrated circuit determines that the reference signal has not been received by the detection operation performed during hover, the integrated circuit performs a subsequent detection operation of the reference signal according to a frame position acquired based on the received reference signal. A pen according to claim 2 or 3.

5. After transmitting the reference change signal, the integrated circuit determines that it will become a slave for synchronization of the frame position in response to a change from being in contact to being in hover, and performs a subsequent operation of detecting the reference signal in accordance with the frame position acquired based on the received reference signal. A pen according to any one of claims 2 to 4.

6. Further comprising a pressure sensor; When the integrated circuit determines that the reference signal has not been received by the detection operation, the integrated circuit switches between transmitting and stopping the reference change signal in accordance with the writing pressure value supplied from the pressure sensor.

10. The pen of claim 1.

7. 1. A system including a pen and a touch controller configured to send and receive signals to each other using a frame, The pen is performing a first detection operation using the pen tip electrode according to a frame position acquired based on the reference signal transmitted by the touch controller, to detect the next reference signal; determining whether the reference signal is received by the first detection operation; when it is determined that the reference signal has not been received by the first detection operation, transmitting a reference change signal indicating that the device itself will become a master for synchronization of the frame position by short-range wireless communication; The touch controller performing a second detection operation for detecting the reference change signal by the short-range wireless communication for each frame; determining whether the reference change signal is received by the second detection operation; When it is determined that the reference change signal has been received by the second detection operation, the frame position is acquired according to a signal transmitted by the pen. system.

8. when it is determined that the reference change signal has not been received by the second detecting operation, the touch controller acquires the frame position based on a blank time of a display. The system of claim 7.

9. The pen is When it is determined that the reference signal has not been received by the first detection operation performed while in contact, the reference change signal is transmitted, When it is determined that the reference signal has not been received by the first detection operation performed during hover, the reference change signal is not transmitted.

9. A system according to claim 7 or 8.

10. The pen is Equipped with a pressure sensor, When the writing pressure value supplied from the pressure sensor is greater than a predetermined value, it is determined that the touch panel is in contact with the object, and when the writing pressure value is not greater than a predetermined value, it is determined that the touch panel is in hovering. The system of claim 9.

11. When it is determined that the reference signal has not been received by the first detection operation performed while the pen is hovering, the pen performs a subsequent detection operation for the reference signal according to a frame position acquired based on the received reference signal. A pen according to claim 9 or 10.

12. After transmitting the reference change signal, the pen determines that it will become a slave for synchronization of the frame position in response to a change from contact to hover, and performs the subsequent first detection operation according to the frame position acquired based on the received reference signal. A pen according to any one of claims 9 to 11.

13. The pen is Equipped with a pressure sensor, when it is determined that the reference signal has not been received by the first detection operation, switching between transmission and stop of the reference change signal in accordance with the writing pressure value supplied from the pressure sensor. A pen according to claim 7 or 8.

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