Pen

Abstract

To continue supply of a pen pressure value to a sensor controller even in a state where a pen cannot transmit the pen pressure value from a pen tip electrode due to a reason such as non-reception of an uplink signal, and to update contact state information held in the sensor controller without delay.SOLUTION: A pen according to the present invention is a pen that transmits a signal based on contact state information indicating whether or not a pen tip is in contact with a touch surface from a pen tip electrode, and transmits a pen pressure value indicating a pressure applied to the pen tip by short-range wireless communication.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an active pen, a position detection system, and an integrated circuit, and more particularly to an active pen that communicates bidirectionally with a sensor controller, an integrated circuit used in such an active pen, and a position detection system including such an active pen and a sensor controller. [Background technology]

[0002] Active pens are known that are configured to transmit and receive signals bidirectionally with a sensor controller in a position detection device through an electrode provided at the pen tip (hereinafter referred to as a "pen tip electrode"). Hereinafter, communication performed through the pen tip electrode in this manner will be referred to as "pen tip communication." Furthermore, a signal transmitted from the sensor controller to the active pen will be referred to as an "uplink signal," and a signal transmitted from the active pen to the sensor controller will be referred to as a "downlink signal."

[0003] The downlink signal serves as a position signal for the sensor controller to detect the position of the active pen, and as a data signal for transmitting data in the active pen to the sensor controller. The sensor controller, which performs pen tip communication, detects the position of the active pen based on the reception strength of the downlink signal at each of a plurality of sensor electrodes provided in the touch surface, and is configured to receive data transmitted by the active pen by demodulating the downlink signal detected at any of the sensor electrodes. The position detected by the sensor controller and the received data are supplied to the host processor and used for drawing by pen input.

[0004] In recent years, electronic pens that support short-range wireless communication such as Bluetooth (registered trademark) have also appeared. Examples of such electronic pens are disclosed in Patent Documents 1 and 2. The electronic pen described in Patent Document 1 is configured to perform initial settings based on information received from a position detection device via short-range wireless communication, and to be able to transmit pen pressure information, side switch information, and identification information ID via short-range wireless communication. In the electronic pen described in Patent Document 2, short-range wireless communication is used to switch the function of the electronic pen, for example, from "draw" to "erase." [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6487782 [Patent Document 2] U.S. Patent No. 9,924,019 Summary of the Invention [Problem to be solved by the invention]

[0006] The sensor controller is configured to periodically transmit an uplink signal, and the active pen is configured to transmit a downlink signal and receive the next uplink signal using the timing of receiving the uplink signal as a reference time. Therefore, in order for the active pen to function properly, it must be able to receive the uplink signal.

[0007] However, noise, such as that from a signal used to drive display pixels, can be superimposed on the uplink signal, causing the active pen to fail to receive the uplink signal. This prevents the active pen from transmitting at least the downlink signal as a data signal. This is because the sensor controller and the active pen must be synchronized in order for the sensor controller to correctly receive the data signal. Pen input stops working if the active pen cannot transmit the data signal, so an improvement was needed.

[0008] Therefore, one object of the present invention is to provide an active pen, a position detection system, and an integrated circuit that can prevent drawing by pen input from being stopped due to failure to receive an uplink signal.

[0009] Furthermore, conventional sensor controllers determine whether the active pen is in contact with the touch surface based on the pen pressure value included in the data signal. Hereinafter, information indicating this determination result will be referred to as "contact state information." The contact state information indicates either a state in which the active pen is not in contact with the touch surface (hover state) or a state in which the active pen is in contact with the touch surface (contact state).

[0010] However, because the active pen transmits data signals intermittently, the above determination method may cause delays in updating the contact state information by the sensor controller. Furthermore, if the active pen transmits data signals by short-range wireless communication rather than pen tip communication, communication delays may also cause delays in updating the contact state information.

[0011] Therefore, another object of the present invention is to provide an active pen and a position detection system that can suppress delays in updating contact state information by a sensor controller. [Means for solving the problem]

[0012] An active pen according to a first aspect of the present invention includes a signal processing unit that transmits a position signal and a data signal from the pen tip electrode and receives the next uplink signal at a timing determined using the reception timing of an uplink signal received from a sensor controller as a reference time, and a first wireless communication unit that performs short-range wireless communication with the sensor controller, wherein the signal processing unit determines whether the next uplink signal has been received at that timing, and if it determines that it has not been received, transmits the position signal from the pen tip electrode while transmitting at least a portion of the data signal by the first wireless communication unit.

[0013] A position detection system according to a first aspect of the present invention is a position detection system including the above-mentioned active pen and the sensor controller, wherein the sensor controller outputs to a host processor the data indicated by the data signal transmitted by the active pen from the pen tip electrode and the data indicated by the data signal transmitted by the active pen via the first wireless communication unit as data from the same active pen.

[0014] An integrated circuit according to a first aspect of the present invention is an integrated circuit used in an active pen that includes a first wireless communication unit that performs short-range wireless communication with a sensor controller, and transmits a position signal and a data signal from the pen tip electrode and receives the next uplink signal at a timing determined using the reception timing of an uplink signal received from the sensor controller as a reference time, determines whether the next uplink signal has been received at that timing, and if it determines that it has not been received, transmits the position signal from the pen tip electrode while transmitting at least a portion of the data signal by the first wireless communication unit.

[0015] An active pen according to a second aspect of the present invention is an active pen that includes a processing circuit that generates a downlink signal to be transmitted to a sensor controller, and a transmitting circuit that transmits the downlink signal by changing the potential of an electrode provided at the pen tip, wherein the processing circuit generates the downlink signal based on a first carrier signal when the active pen is in a contact state, and performs processing to generate the downlink signal based on a second carrier signal different from the first carrier signal when the active pen is in a hover state.

[0016] A position detection system according to a second aspect of the present invention is a position detection system including the active pen and the sensor controller, wherein the sensor controller determines whether the carrier signal of the downlink signal received from the active pen is the first carrier signal or the second carrier signal, and based on the result of the determination, determines whether the active pen is in contact with a touch surface. [Effects of the Invention]

[0017] According to the first aspect of the present invention, even if the uplink signal is not received and the active pen is unable to transmit a data signal from the pen tip electrode, the sensor controller can detect the position of the active pen using the position signal transmitted from the pen tip electrode and can receive the transmitted data from the active pen via short-range wireless communication. This makes it possible to prevent drawing by pen input from being interrupted due to failure to receive the uplink signal.

[0018] According to the second aspect of the present invention, contact state information can be transmitted by the carrier signal of the downlink signal, so that it is possible to suppress delays in updating of contact state information by the sensor controller. [Brief explanation of the drawings]

[0019] [Figure 1]1 is a diagram showing a configuration of a position detection system 1 according to a first embodiment of the present invention. [Figure 2] FIG. 10 is a state transition diagram of the processing circuit 26d of the active pen 2. [Figure 3] (a) is a diagram showing the format of an uplink signal US, (b) and (c) are diagrams showing the format of a downlink signal DSa, (d) is a diagram showing the format of a downlink signal DSb, and (e) is a diagram showing the format of a downlink signal DSc. [Figure 4] 10 is a processing flow diagram showing processing performed by a processing circuit 26d of the active pen 2. FIG. [Figure 5] 10 is a processing flow diagram showing processing performed by a processing circuit 26d of the active pen 2. FIG. [Figure 6] 4 is a process flow diagram showing the process performed by the sensor controller 31. FIG. [Figure 7] 4 is a process flow diagram showing the process performed by the sensor controller 31. FIG. [Figure 8] 4 is a process flow diagram showing the process performed by the sensor controller 31. FIG. [Figure 9] 4 is a process flow diagram showing the process performed by the sensor controller 31. FIG. [Figure 10] FIG. 10 is a diagram showing signals transmitted and received between an active pen 2 and a sensor controller 31 that constitute a position detection system 1 according to a second embodiment of the present invention. [Figure 11] FIG. 10 is a diagram showing signals transmitted and received between an active pen 2 and a sensor controller 31 that constitute a position detection system 1 according to a modified example of the second embodiment of the present invention. [Figure 12] FIG. 10 is a diagram showing signals transmitted and received between an active pen 2 and a sensor controller 31 that constitute a position detection system 1 according to a third embodiment of the present invention. [Figure 13] FIG. 10 is a diagram showing signals transmitted and received between an active pen 2 and a sensor controller 31 that constitute a position detection system 1 according to a modified example of the third embodiment of the present invention. [Figure 14]FIG. 10 is a diagram showing signals transmitted and received between the active pen 2 and the sensor controller 31 when transmission and reception of uplink signals US and downlink signals DS are performed in time slot units. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0021] 1 is a diagram showing the configuration of a position detection system 1 according to a first 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.

[0022] 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 sensor controller 31 connected to the sensor 30, a display 32 arranged superimposed on the sensor 30, a wireless communication unit 33 (second wireless communication unit), and a host processor 34 that controls each unit of the electronic device 3 including these.

[0023] The host processor 34 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 supplied from the sensor 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 34, and is configured, for example, by a liquid crystal display or an organic EL display.

[0024] The sensor controller 31 is an integrated circuit that has the function of deriving the position of the active pen 2 within the touch surface 3a by bidirectionally communicating with the active pen 2, acquiring data from the active pen 2, and supplying the derived position and acquired data to the host processor 34 each time. In principle, communication between the sensor controller 31 and the active pen 2 is carried out by the pen tip communication described above, but short-range wireless communication may also be used depending on the situation.

[0025] Specifically, communication from the sensor controller 31 to the active pen 2 is performed by pen tip communication. Hereinafter, the signal transmitted from the sensor controller 31 to the active pen 2 for this communication will be referred to as the "uplink signal US." Meanwhile, communication from the active pen 2 to the sensor controller 31 is generally performed by pen tip communication, but short-range wireless communication is also used in conjunction with this communication only if the active pen 2 fails to receive the uplink signal US. Hereinafter, a signal transmitted by pen tip communication from an active pen 2 that successfully receives the uplink signal US will be referred to as the "downlink signal DSa," a signal transmitted by pen tip communication from an active pen 2 that fails to receive the uplink signal US will be referred to as the "downlink signal DSb," and a signal transmitted by short-range wireless communication from an active pen 2 that fails to receive the uplink signal US will be referred to as the "downlink signal DSc." Furthermore, when it is not necessary to distinguish between these signals, the downlink signals DSa, DSb, and DSc will be collectively referred to as the "downlink signal DS."

[0026] The sensor 30 is a device having a structure in which multiple sensor electrodes are arranged within the touch surface 3a. Pen tip communication is performed by electrostatic coupling communication via capacitance formed between these multiple sensor electrodes and electrodes on the active pen 2 side (pen tip electrode 21 and ring electrode 22, described below). The sensor controller 31 transmits an uplink signal US by changing the potential of each sensor electrode, and receives downlink signals DSa and DSb by detecting changes in the potential of each sensor electrode.

[0027] Here, 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.

[0028] The wireless communication unit 33 is a communication device for performing short-range wireless communication such as Bluetooth (registered trademark), and is connected to the sensor controller 31 and the host processor 34. The host processor 34 controls the wireless communication unit 33, including pairing with a communication partner, and performs short-range wireless communication for general purposes such as connecting a keyboard, mouse, speaker, and headphones via the wireless communication unit 33. Meanwhile, the sensor controller 31 uses the wireless communication unit 33 to receive the downlink signal DSc through short-range wireless communication.

[0029] As shown in FIG. 1, the active pen 2 is configured to have a core body 20, a pen tip electrode 21, a ring electrode 22, a pressure sensor 23, a side switch 24, a battery 25, an integrated circuit 26, a stop filter 27, and a wireless communication unit 28 (first wireless communication unit). 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 23. The pen tip electrode 21 and the ring electrode 22 are conductors provided at different positions on the pen tip. More specifically, the pen tip electrode 21 is located at the tip of the core body 20 of the active pen 2, and the ring electrode 22 is located closer to the center of the active pen 2 than the pen tip electrode 21, so as to surround the core body 20.

[0030] The pressure sensor 23 is a sensor that detects the pressure applied to the tip (pen tip) of the core body 20. The pressure detected by the pressure sensor 23 is supplied to the integrated circuit 26 as, for example, a 12-bit writing pressure value. The side switch 24 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 24 is supplied to the integrated circuit 26 as, for example, 2-bit switch information. The battery 25 serves to supply the power necessary for the integrated circuit 26 to operate.

[0031] The wireless communication unit 28 is a communication device for performing short-range wireless communication such as Bluetooth (registered trademark). The active pen 2 uses the wireless communication unit 28 to transmit a downlink signal DSc to the sensor controller 31.

[0032] The integrated circuit 26 is an integrated circuit configured with various circuits including a boost circuit 26a, a transmission circuit 26b, a reception circuit 26c, and a processing circuit 26d. The transmission circuit 26b is connected to the pen tip electrode 21 and serves to transmit downlink signals DSa and DSb by changing the potential of the pen tip electrode 21 using the boost circuit 26a. The reception circuit 26c is connected to the ring electrode 22 and serves to receive the uplink signal US by detecting changes in the potential of the ring electrode 22.

[0033] The processing circuit 26d is a circuit (signal processing unit) that executes processing in response to the uplink signal US received by the receiving circuit 26c. This processing includes a process of determining a transmission / reception schedule for the downlink signal DS and the next uplink signal US using the reception timing of the uplink signal US as a reference time, a process of generating the downlink signal DS in response to a command from the sensor controller 31 and causing the transmission circuit 26b or the wireless communication unit 28 to transmit it, and a process of causing the receiving circuit 26c to receive the next uplink signal US.

[0034] 2 is a state transition diagram of the processing circuit 26d. As shown in the figure, the processing circuit 26d is configured to operate in any one of discovery mode, normal mode, and dual transmission mode. The initial state is discovery mode, and the processing circuit 26d, which has entered the discovery mode, causes the receiving circuit 26c to continuously or intermittently perform an operation to detect the uplink signal US (step S1).

[0035] If an uplink signal US is detected as a result of the detection operation in step S1, the processing circuit 26d enters normal mode (step S2). Then, the processing circuit 26d determines a transmission / reception schedule for the downlink signal DS and the next uplink signal US using the reception timing of the uplink signal US as a reference time, and causes the transmission circuit 26b to transmit the downlink signal DSa according to the determined schedule (step S10). Furthermore, when the reception timing of the next uplink signal US arrives (step S11), the processing circuit 26c causes the reception circuit 26c to perform a detection operation for the next uplink signal US (step S12). If the next uplink signal US is detected as a result (step S13), the processing circuit 26d determines a new transmission / reception schedule using the reception timing of the uplink signal US as a reference time, and repeats the processing in step S10.

[0036] On the other hand, if an uplink signal is not detected as a result of the detection operation in step S12, the processing circuit 26d enters dual transmission mode (step S14). In dual transmission mode, the processing circuit 26d generates a downlink signal DSb and causes the transmission circuit 26b to transmit it, and also generates a downlink signal DSc and causes the wireless communication unit 28 to transmit it (step S20). In step S20, in parallel with the transmission of the downlink signals DSb and DSc, the processing circuit 26d also performs processing to cause the reception circuit 26c to perform an operation to detect an uplink signal US. This parallel processing is realized by the stop filter 27 shown in FIG. 1, and its details will be described later.

[0037] If an uplink signal US is detected in step S20, the processing circuit 26d returns to the normal mode (step S21). Then, a new transmission / reception schedule is determined using the reception timing of the uplink signal US as the reference time, and the processing of step S10 is repeated. On the other hand, if the state in which an uplink signal US is not detected continues for a predetermined time, the processing circuit 26d returns to the discovery mode and continues processing (step S22). In this case, the transmission of the downlink signal DS is stopped.

[0038] Returning to FIG. 1, the processing circuit 26d includes an oscillator circuit that generates a clock signal of a predetermined frequency, and a frequency divider circuit that generates a carrier signal by dividing the clock signal generated by the oscillator circuit. The predetermined frequency is, for example, 8 MHz. For example, if the frequency division ratio of the frequency divider circuit is 20, the frequency of the carrier signal is 8 MHz ÷ 20 = 400 kHz. The processing circuit 26d is configured to generate downlink signals DSa and DSb based on the carrier signal generated by the frequency divider circuit. The processing circuit 26d is also configured with a function to change the frequency division ratio of the frequency divider circuit.

[0039] The stop filter 27 is a filter circuit inserted between the ring electrode 22 and the integrated circuit 26 to simultaneously detect the uplink signal US using the ring electrode 22 and transmit the downlink signal DSb from the pen tip electrode 21. More specifically, the boost circuit 26a used to transmit the downlink signal DS increases the potential by as much as 18 to 20 V, so the change in the potential of the pen tip electrode 21 accompanying the transmission of the downlink signal DS also affects the receiving circuit 26c. As a result, the downlink signal DSb is superimposed on the potential of the uplink signal US detected by the receiving circuit 26c, making it difficult to detect the uplink signal US simultaneously with the transmission of the downlink signal DSb. When the active pen 2 is in a hover state (when the pen tip is away from the touch surface 3a) and the ring electrode 22 is far from the sensor 30, the received strength of the uplink signal US decreases, making detection of the uplink signal US even more difficult. The stop filter 27 prevents the change in potential of the pen tip electrode 21 due to the transmission of the downlink signal DSb from affecting the potential of the uplink signal US detected by the receiving circuit 26c in the integrated circuit 26, thereby enabling the detection of the uplink signal US using the ring electrode 22 and the transmission of the downlink signal DSb from the pen tip electrode 21 to be performed simultaneously.

[0040] The stop filter 27 may be configured in various ways. For example, if the downlink signal DSb is a signal based on a sine wave, the stop filter 27 may be configured as a band-stop filter (notch filter) that blocks a specific frequency band including the frequency of the downlink signal DSb. If the downlink signal DSb is a pulse wave, the stop filter 27 may be configured as a high-pass filter that passes the pulse wave that constitutes the uplink signal US while blocking the pulse wave that constitutes the downlink signal DSb. Alternatively, a mute circuit for muting the edges of the downlink signal DSb may be provided downstream of the high-pass filter. Alternatively, the stop filter 27 may be configured by a combination of a gain circuit and a differential circuit, or a combination of an FIR (Finite Impulse Response) filter, a subtractor, and a feedback circuit, thereby removing the downlink signal DSb from the signal arriving at the ring electrode 22.

[0041] 3(a) to 3(e) are diagrams showing the formats of the uplink signal US and the downlink signals DSa, DSb, and DSc. Referring first to FIG. 3(a), the uplink signal US is configured with local identifiers LID and NLID, a command COM, and an error detection code CRC.

[0042] The local identifiers LID and NLID are identification information assigned by the sensor controller 31 to the active pen 2 with which it will perform pen tip communication. An active pen 2 that has not yet started communication with the sensor controller 31 extracts the local identifier NLID from the uplink signal US detected as a result of the detection operation and stores it as its own local identifier, thereby pairing with the sensor controller 31.

[0043] The command COM is information indicating an instruction to the active pen 2. The local identifier LID placed at the beginning of the command COM indicates the destination of the command COM. When the active pen 2 receives the uplink signal US, it first references the local identifier LID and determines whether it matches the local identifier stored in its memory. If it determines that it matches, it performs processing to generate a data signal DATA, which will be described later, in accordance with the command COM.

[0044] 3(b) and 3(c), the downlink signal DSa is composed of a position signal POS1 and a data signal DATA. The position signal POS1 is an unmodulated carrier signal (a carrier signal generated by the above-mentioned frequency divider circuit) and is used by the sensor controller 31 to detect the position of the active pen 2 within the touch surface 3a. The sensor controller 31 acquires the reception strength of the position signal POS1 at each of the multiple sensor electrodes that make up the sensor 30, and detects the position of the active pen 2 based on the distribution of the reception strength. On the other hand, the data signal DATA is a signal obtained by modulating the carrier signal generated by the above-mentioned frequency divider circuit with data transmitted from the active pen 2 to the sensor controller 31.

[0045] The downlink signal DSa shown in FIG. 3(b) is a signal transmitted by the active pen 2 immediately after storing the above-mentioned local identifier NLID. As shown in the figure, the downlink signal DSa in this case is composed of a local identifier LID, a global identifier GID, and an error detection code CRC. Of these, the local identifier LID is set to the stored local identifier NLID. This also applies to the other downlink signals DS described later. The global identifier GID is an identifier assigned to the active pen 2 at the time of shipment from the factory, and serves to notify the sensor controller 31 of the type, function, version, etc. of the active pen 2. When the sensor controller 31 receives a downlink signal DSa including an unpaired local identifier LID, it extracts the local identifier LID and global identifier GID from the signal, associates them with each other, and stores them, thereby pairing with the active pen 2.

[0046] The downlink signal DSa shown in FIG. 3(c) is a signal transmitted by the active pen 2 when no particular instruction is given by the command COM. The active pen 2 is configured to periodically transmit this downlink signal DSa when no particular instruction is given by the command COM. As shown in the figure, the downlink signal DSa in this case is composed of a local identifier LID, a writing pressure value PRE, switch information SW, and an error detection code CRC. The writing pressure value PRE is information supplied from the pressure sensor 23 shown in FIG. 1 to the integrated circuit 26, and the switch information SW is information indicating the operating state of the side switch 24 shown in FIG. 1.

[0047] Next, referring to FIG. 3(d), the downlink signal DSb is configured to include only the position signal POS2, which is an unmodulated carrier signal similar to the position signal POS1. The downlink signal DSb is transmitted when the active pen 2 loses the timing of transmitting the downlink signal DS (i.e., when the active pen 2 is not synchronized with the sensor controller 31). Therefore, even if the data signal DATA is included in the downlink signal DSb, it cannot be expected that the sensor controller 31 will be able to correctly demodulate it. On the other hand, like the position signal POS1 described above, the position signal POS2 is used to detect the position of the active pen 2 based on the distribution of reception strength at each of the multiple sensor electrodes that make up the sensor 30. Therefore, the sensor controller 31 does not need to demodulate the position signal POS2, at least to detect the position. Therefore, in this embodiment, the active pen 2 is configured to transmit only the position signal POS2 as the downlink signal DSb, so that the sensor controller 31 can detect the position of the active pen 2 even when the active pen 2 and the sensor controller 31 are not synchronized.

[0048] However, in this embodiment, even if the active pen 2 and the sensor controller 31 are not synchronized, the position signal POS2 also serves to transmit certain information to the sensor controller 31 to the extent possible. The content of the certain information is, for example, one-bit information indicating whether the active pen 2 is in contact with the touch surface 3a. This information is none other than the contact state information described above. In this case, the processing circuit 26d of the active pen 2 acquires the contact state information by determining whether the active pen 2 is in contact with the touch surface 3a based on the writing pressure value supplied from the pressure sensor 23 shown in FIG. 1. Then, based on the acquired contact state information, the position signal POS2 is modulated by any one of frequency modulation, spectrum spread, and phase modulation.

[0049] Specifically, when frequency modulation is used, the processing circuit 26d changes the frequency of the position signal POS2 by changing the division ratio of the above-mentioned frequency divider circuit depending on whether the active pen 2 is in contact with the touch surface 3a or not. In a typical example, it is preferable to set the division ratio to 20 when the active pen 2 is in contact with the touch surface 3a and 21 or 19 when the active pen 2 is not in contact with the touch surface 3a. In this case, the frequency of the position signal POS2 is 400 kHz when the active pen 2 is in contact with the touch surface 3a, and 381 kHz or 421 kHz when the active pen 2 is not in contact with the touch surface 3a. The sensor controller 31 demodulates the information transmitted by the processing circuit 26d by detecting the frequency of the position signal POS2 using asynchronous detection.

[0050] Next, when using spread spectrum, the processing circuit 26d generates the position signal POS2 using different spread codes depending on whether the active pen 2 is in contact with the touch surface 3a or not. The sensor controller 31 detects the spread code included in the position signal POS2, i.e., the information transmitted by the processing circuit 26d, by continuously calculating the correlation with each of the two types of spread codes used by the processing circuit 26d.

[0051] Finally, when phase modulation is used, the processing circuit 26d is configured to generate the position signal POS2 by changing the phase at predetermined intervals. The processing circuit 26d sets the amount of phase change to a different value depending on whether the active pen 2 is in contact with the touch surface 3a. The sensor controller 31 demodulates the information transmitted by the processing circuit 26d by detecting the amount of phase change using differential detection.

[0052] The processing circuit 26d transmits the contact state information as described above, which has the effect that the position detection system 1 according to this embodiment can suppress delays in updating the contact state information by the sensor controller 31. This point will be described in more detail later in the second and third embodiments and their modifications.

[0053] Next, referring to Fig. 3(e), the downlink signal DSc is configured to include any data including the local identifier LID assigned to the active pen 2. Note that, because the downlink signal DSc is transmitted by short-range wireless communication, various types of information corresponding to lower levels of the protocol stack, such as the destination address and source address of the short-range wireless communication, are added to the actual downlink signal DSc, but Fig. 3(e) omits the depiction of this information and shows only the information corresponding to higher levels of the protocol stack.

[0054] As shown in Fig. 3(e), the downlink signal DSc may include the pen pressure value PRE, switch information SW, and error detection code CRC, similar to the downlink signal DSa shown in Fig. 3(c). This allows the downlink signal DSc to serve as an alternative transmission means when the active pen 2 is not synchronized with the sensor controller 31 and therefore cannot transmit this information by pen tip communication.

[0055] The sensor controller 31 is configured to output the position detected by the downlink signals DSa and DSb and the data received by the downlink signals DSa and DSc to the host processor as data from the same active pen 2. More specifically, the sensor controller 31 generates a data stream for each local identifier LID to supply data to the host processor 34, and is configured to sequentially combine the position detected by the downlink signals DSa and DSb and the data received by the downlink signals DSa and DSc into this data stream. This allows the host processor 34 to process data received by the sensor controller 31 via short-range wireless communication in the same way as data received via pen tip communication.

[0056] Here, because the downlink signals DSa and DSb are transmitted according to a transmission / reception schedule, the sensor controller 31 can acquire the local identifier LID indicating the source of the downlink signals DSa and DSb based on the reception timing of the downlink signals DSa and DSb. Therefore, even if the local identifier LID is not included in the downlink signals DSa and DSb, the sensor controller 31 can combine the position and transmission data of the active pen 2 acquired from the downlink signals DSa and DSb into the corresponding data stream.

[0057] In contrast, the downlink signal DSc is transmitted regardless of the transmission / reception schedule, and therefore the sensor controller 31 cannot acquire the local identifier LID indicating the source of the downlink signal DSc even by referring to the reception timing of the downlink signal DSc. In principle, it is possible to acquire the local identifier LID indicating the source of the downlink signal DSc by storing the source address of the short-range wireless communication in association with the local identifier LID and referring to the source address included in the downlink signal DSc, but to do so, the sensor controller 31 must refer to information corresponding to a lower level in the protocol stack of the short-range wireless communication.

[0058] Therefore, in this embodiment, by arranging the local identifier LID in the downlink signal DSc, the sensor controller 31 can determine the local identifier LID indicating the sender of the downlink signal DSc only from information corresponding to the upper level of the short-range wireless communication protocol stack. This allows the sensor controller 31 to combine the transmission data of the active pen 2 obtained from the downlink signal DSc into a corresponding data stream without the sensor controller 31 having to refer to information corresponding to the lower level of the short-range wireless communication protocol stack.

[0059] The processing described above will be explained in more detail below with reference to a processing flow diagram showing the processing of the processing circuit 26d and the sensor controller 31.

[0060] 4 and 5 are processing flow diagrams showing the processing performed by the processing circuit 26d of the active pen 2. As shown in the figures, the processing circuit 26d first enters discovery mode (step S100). Then, it causes the receiving circuit 26c to perform an operation to detect an uplink signal US (step S101), and as a result, it determines whether or not an uplink signal US has been received (step S102). If the processing circuit 26d determines that an uplink signal US has not been received, it repeats the processing from step S101. On the other hand, if the processing circuit 26d determines that an uplink signal US has been received, it enters normal mode (step S103). Then, it extracts and stores the local identifier NLID from the uplink signal US, thereby performing pairing for pen tip communication with the sensor controller 31 (step S104).

[0061] Next, the processing circuit 26d acquires the short-range wireless communication address of the sensor controller 31 (step S105). This address is specifically the address of the wireless communication unit 33 shown in FIG. 1, and is set in advance in the processing circuit 26d by a user operation. Next, the processing circuit 26d determines whether pairing for short-range wireless communication has been established with the device indicated by the acquired address, and if not, executes pairing for short-range wireless communication with the device using the wireless communication unit 28 shown in FIG. 1 (step S106).

[0062] Next, the processing circuit 26d determines a transmission / reception schedule for the downlink signal DS and the next uplink signal US using the reception timing of the last received uplink signal US as a reference time (step S107), transmits the downlink signal DSa (step S108) according to the determined transmission / reception schedule, and detects the next uplink signal US (step S109).Then, as a result of step S109, it determines whether the uplink signal US has been received (step S110), and if it is determined that the uplink signal US has been received, it repeats the processing from step S107, but if it is determined that the uplink signal US has not been received, it enters the dual transmission mode (step S120).

[0063] The processing circuit 26d that has entered the dual transmission mode generates the position signal POS2 shown in FIG. 3(d) based on the pen pressure value being detected (the latest pen pressure value supplied from the pressure sensor 23) (step S121). That is, the position signal POS2 is generated by modulating the carrier signal based on whether or not the active pen 2 is in contact with the touch surface 3a. The processing circuit 26d then continuously transmits the downlink signal DSb while continuing to detect the uplink signal US (step S122). This simultaneous reception and transmission is a process that can be realized by the stop filter 27 shown in FIG. 1, as described above.

[0064] The processing circuit 26d also determines whether the pen pressure value being detected is 0 or a value greater than 0 (step S123), and if it determines that the value is greater than 0, performs processing for transmitting a downlink signal DSc. Specifically, if the wireless communication unit 28 is in a power-saving mode, the processing circuit 26d first switches the wireless communication unit 28 to a normal mode (step S124) and then transmits a downlink signal DSc using short-range wireless communication (step S125). If the wireless communication unit 28 has not been used for a while, it enters the power-saving mode and becomes unable to communicate. Step S124 is processing for restoring the wireless communication unit 28 to a state where communication is possible in such a case. The reason for not transmitting the downlink signal DSc when the pen pressure value being detected is 0 is to reduce power consumption by the wireless communication unit 28, since digital ink is not being generated when the pen pressure value being detected is 0 and there is little need to immediately transmit the pen pressure value or switch information.

[0065] Next, the processing circuit 26d determines whether or not an uplink signal US has been received through the detection operation performed in step S122 (step S126). If the processing circuit 26d determines that an uplink signal US has been received, it transitions to step S103 of FIG. 4, returns to normal mode, and continues processing. On the other hand, if the processing circuit 26d determines that an uplink signal US has not been received in step S126, it determines whether or not a predetermined time has elapsed since the last time the uplink signal US was received (step S127). If it determines that the predetermined time has not elapsed, it returns to step S121 and repeats the dual transmission mode processing. If it determines that the predetermined time has elapsed, it returns to step S100 and enters discovery mode. This prevents the downlink signals DSb and DSc from continuing to be transmitted even though the active pen 2 has moved away from the electronic device 3.

[0066] 6 to 9 are processing flow diagrams showing the processing performed by the sensor controller 31. As shown in the figures, the sensor controller 31 first determines a transmission / reception schedule for the uplink signal US and the downlink signal DS (step S200). The transmission / reception schedule determined here includes the transmission cycle of the uplink signal US and the reception timing of the downlink signal DS for each local identifier LID (the timing determined with the transmission timing of the uplink signal US as the reference time). The transmission / reception schedule is predetermined in the protocol for the active electrostatic method and is shared in advance between the sensor controller 31 and the active pen 2.

[0067] Here, multiple transmission / reception schedules that vary depending on conditions such as the number of active pens 2 being detected may be prepared in advance, and the sensor controller 31 may change the transmission / reception schedule when the conditions are met. Each time a schedule change is made, information indicating the transmission / reception schedule to be used may be notified to each active pen 2 using a command COM in the uplink signal US. This enables effective use of communication resources of the active electrostatic system. Furthermore, if the electronic device 3 is the in-cell type described above, the sensor controller 31 may determine the transmission / reception schedule based on information about the pixel drive cycle of the display 32 acquired from the host processor 34 shown in FIG. 1. This makes it possible to avoid failures in signal transmission / reception due to noise generated by the display 32.

[0068] Next, the sensor controller 31 determines whether the timing for transmitting the uplink signal US indicated in the determined transmission / reception schedule has arrived (step S201), and if it has arrived, transmits the uplink signal US (step S202). On the other hand, if the sensor controller 31 determines that the timing has not arrived, it determines whether the timing for receiving the position signal POS1 and the data signal DATA has arrived for each local identifier LID (steps S203 and S204). If it determines that neither timing has arrived, the sensor controller 31 returns to step S201 and repeats the process. On the other hand, if it determines that the timing for receiving the position signal POS1 has arrived, the process proceeds to step S210 shown in FIG. 7, and if it determines that the timing for receiving the data signal DATA has arrived, the process proceeds to step S220 shown in FIG. 8. The process shown in FIGS. 7 to 9 will be described below using the case where the local identifier LID is equal to n as an example.

[0069] 7, the sensor controller 31 derives the pointed position of the active pen 2 based on the reception strength of the signal at each of the multiple sensor electrodes constituting the sensor 30 shown in FIG. 1 (step S210). Then, it is determined whether the pointed position of the active pen 2 has been derived (step S211). If it is determined that the pointed position has not been derived, the process returns to step S201 in FIG. 6. On the other hand, if it is determined in step S211 that the pointed position has been derived, the sensor controller 31 regards the received signal as a position signal POS2, performs a demodulation process, and attempts to acquire information transmitted by the processing circuit 26d of the active pen 2 (step S212). Here, assuming that the information acquired in step S212 is information indicating the contact state (contact state with the touch surface 3a) of the active pen 2, the sensor controller 31 will refer to this information in step S230 (described later) that is executed if the data signal DATA has not been received. If the received signal is the position signal POS1 or some other signal, the information obtained in step S212 will not be significant, but in this case the sensor controller 31 will not execute step S230 described below, so this is not a particular problem.

[0070] Next, the sensor controller 31 generates a data stream for LID=n if it has not been generated yet (step S213), and combines the detected pointing position with the data stream for LID=n (step S214). As a result, the pointing position of the active pen 2 corresponding to LID=n is supplied to the host processor 34.

[0071] 8, the sensor controller 31 selects one sensor electrode based on the most recent pointing position of the corresponding active pen 2 (step S220), and executes a detection operation of the data signal DATA using the selected sensor electrode (step S221). Then, it determines whether the data signal DATA is detected (step S222).

[0072] If the sensor controller 31 determines in step S222 that the data signal DATA has been detected, it demodulates the detected data signal DATA to acquire transmission data from the active pen 2 (step S223). Next, the sensor controller 31 determines whether pairing for pen tip communication has been established with the active pen 2 of LID=n (step S224). If pairing for pen tip communication has not been established, it acquires a global identifier GID from the data acquired in step S223 (step S225), and stores the acquired global identifier GID in association with LID=n, thereby performing pairing for pen tip communication with the active pen 2 (step S226).

[0073] The sensor controller 31 further acquires a short-range wireless communication address corresponding to the global identifier GID (step S227). This address is specifically the address of the wireless communication unit 28 shown in FIG. 1, and is set in advance in the sensor controller 31 by a user operation in association with the global identifier GID of the active pen 2. Next, the sensor controller 31 determines whether pairing via short-range wireless communication has been established with the device indicated by the acquired address, and if not, instructs the host processor 34 to execute pairing (step S228). Upon receiving this instruction, the host processor 34 uses the wireless communication unit 33 shown in FIG. 1 to execute pairing via short-range wireless communication with the address acquired by the sensor controller 31 in step S227.

[0074] If it is determined in step S224 that the connection has been established, or if step S228 is completed, the sensor controller 31 combines the data acquired in step S223 into a data stream for LID=n (step S229), and returns the process to step S201 in Fig. 6. By executing step S229, the sensor controller 31 supplies the transmission data of the active pen 2 corresponding to LID=n to the host processor 34.

[0075] The sensor controller 31, which has determined that the data signal DATA has not been detected in step S222 of Fig. 8, determines whether the active pen 2 is in contact (step S230), as shown in Fig. 9. This determination is made based on the information acquired by the sensor controller 31 in step S212 of Fig. 7.

[0076] If the sensor controller 31 determines in step S230 that contact is in progress, it switches the wireless communication unit 33 to normal mode if it is in power saving mode (step S231), and then checks whether a data signal (downlink signal DSc) of LID=n is received by short-range wireless communication (step S232), and determines the result (step S233). Note that step S231 is necessary for the same reason as step S124 shown in FIG. 5.

[0077] If the sensor controller 31 determines in step S233 that data has been received, it demodulates the received data signal to acquire the transmission data of the active pen 2 corresponding to LID=n (step S234). Then, it combines the acquired transmission data into a data stream for LID=n (step S235) and returns the process to step S201 in Fig. 6. By the sensor controller 31 executing step S235, even if the active pen 2 is no longer able to transmit the data signal DATA from the pen tip electrode 21 due to a failure to receive the uplink signal US, the host processor 34 can continue to acquire the data transmitted by the active pen 2 and can also continue to acquire the position of the active pen 2 through step S215, making it possible to continue drawing using pen input.

[0078] As described above, with the active pen 2 and position detection system 1 according to this embodiment, even if the uplink signal US is not received and the active pen 2 is unable to transmit the data signal DATA from the pen tip electrode 21, the sensor controller 31 can detect the position of the active pen 2 using the position signal POS2 transmitted from the pen tip electrode 21, and can also receive the transmission data of the active pen 2 via short-range wireless communication. This makes it possible to prevent drawing by pen input from being stopped due to failure to receive the uplink signal US.

[0079] Furthermore, contact state information indicating whether or not the active pen 2 is in contact with the touch surface 3a can be transmitted by the position signal POS2, so that when no drawing is being performed by pen input, the use of near-field wireless communication can be stopped, thereby reducing the power consumption of the active pen 2. Another advantage is that delays in updating the contact state information by the sensor controller 31 can be suppressed.

[0080] In addition, a stop filter 27 is provided in the active pen 2, which enables the detection operation of the uplink signal US to be performed in parallel with the transmission of the position signal POS2, so that the active pen 2 can be returned from the dual transmission mode to the normal mode while continuously transmitting the position signal POS2.

[0081] Next, a second embodiment of the present invention will be described in detail. In this embodiment, the operation of the position detection system 1 described in the first embodiment will be described in more detail, focusing on suppressing delays in updating contact state information by the sensor controller 31.

[0082] FIG. 10 is a diagram showing signals transmitted and received between the active pen 2 and the sensor controller 31 that constitute the position detection system 1 of this embodiment. The horizontal axis in the figure is the time axis. Furthermore, the "frames" shown in the figure are transmission cycles of the uplink signal US, and the sensor controller 31 is configured to transmit the uplink signal US at the beginning of each frame. These points also apply to FIGS. 11 to 14, which will be described later.

[0083] 10 is the position signal POS2 transmitted by the active pen 2 in the contact state, and the position signal POS2u is the position signal POS2 transmitted by the active pen 2 in the hover state. The processing circuit 26d according to this embodiment is configured to be able to generate at least two types of carrier signals with different frequencies by controlling the division ratio of the above-mentioned frequency divider circuit, and is configured to generate the position signal POS2d based on one of the carrier signals (first carrier signal) and the position signal POS2u based on the other carrier signal (second carrier signal). More specifically, the processing circuit 26d is configured to obtain the unmodulated first carrier signal as the position signal POS2d and the unmodulated second carrier signal as the position signal POS2u.

[0084] In the example of Fig. 10, the receiving circuit 26c of the active pen 2 is able to receive the uplink signal US transmitted by the sensor controller 31 in the (n-1)th frame. In this case, the downlink signal DS transmitted by the processing circuit 26d is the downlink signal DSa shown in Fig. 3(b) or 3(c), as shown in Fig. 10. The processing circuit 26d transmits the downlink signal DSa using the remaining time after receiving the uplink signal US, and waits to receive the uplink signal US at the beginning of the nth frame.

[0085] 10, the receiving circuit 26c of the active pen 2 fails to receive the uplink signal US transmitted by the sensor controller 31 in the n-th frame. In this case, the processing circuit 26d enters the dual transmission mode as shown in FIG. 4 and transmits a downlink signal DSb, which is the position signal POS2, and at this time performs a process of modulating a carrier signal based on the latest contact state information it has acquired (hereinafter referred to as "carrier modulation process"). Specifically, when the state is contact, the processing circuit 26d generates a position signal POS2d, and when the state is hover, the processing circuit 26d generates a position signal POS2u and transmits the generated signal as a downlink signal DSb.

[0086] 10, at time t1, the contact state information of the active pen 2 switches from the contact state to the hover state, and the processing circuit 26d receiving this switches to transmit the position signal POS2d until time t1 and transmits the position signal POS2u after time t1. As described with reference to FIG. 4, the transmission of the position signal POS2d or the position signal POS2u is executed until the uplink signal US is received, or until a predetermined time has elapsed since the last uplink signal US was received.

[0087] The sensor controller 31 is configured to sequentially determine whether the carrier wave signal of the downlink signal DSb received from the active pen 2 is the first carrier wave signal or the second carrier wave signal, and to determine whether the active pen 2 is in contact with the touch surface 3a based on the determination result. This enables the sensor controller 31 to update the contact state information of the active pen 2 without waiting for the writing pressure value PRE received by pen tip communication or near-field wireless communication.

[0088] In order for the sensor controller 31 to receive both the first carrier signal and the second carrier signal, it is essential that a detector circuit whose reference signal frequency is equal to the frequency of the first carrier signal and a detector circuit whose reference signal frequency is equal to the frequency of the second carrier signal are disposed within the sensor controller 31. However, if the frequency difference between the first and second carrier signals is sufficiently small, such as when the first carrier signal is the 400 kHz signal described above and the second carrier signal is the 381 kHz or 421 kHz signal described above, the sensor controller 31 can also be configured to receive both the first and second carrier signals using a single detector circuit. That is, a detector circuit whose reference signal frequency is, for example, 400 kHz can also detect signals of 381 kHz or 421 kHz, but in that case, the phase output from the detector circuit will gradually change. The sensor controller 31 may determine whether the carrier signal of the received downlink signal DSb is the first carrier signal or the second carrier signal according to this change in phase.

[0089] As described above, the active pen 2 and position detection system 1 according to this embodiment can transmit contact state information by frequency modulation of the carrier signal of the downlink signal DSb, thereby preventing delays in updating the contact state information by the sensor controller 31. If the sensor controller 31 is configured to sequentially supply the updated contact state information to the host processor 33 in this manner, for example, if a drawing application running on the host processor 34 is capable of performing a drawing operation without the pen pressure value PRE, the drawing application can start drawing a stroke without waiting for the pen pressure value PRE to be supplied.

[0090] 11 is a diagram showing signals transmitted and received between the active pen 2 and sensor controller 31 that constitute a position detection system 1 according to a modification of the present embodiment. The position detection system 1 according to this modification differs from the position detection system 1 according to the present embodiment in that it uses a downlink signal DSa instead of a downlink signal DSb to transmit contact state information separately from the pen pressure value PRE in the data signal DATA. The following description will focus on these differences.

[0091] 11 is the position signal POS1 transmitted by the active pen 2 in the contact state, and the position signal POS1u is the position signal POS1 transmitted by the active pen 2 in the hover state. Also, the data signal DATAd shown in Fig. 11 is the data signal DATA transmitted by the active pen 2 in the contact state, and the data signal DATAu is the data signal DATA transmitted by the active pen 2 in the hover state.

[0092] The processing circuit 26d according to this modification is configured to generate a position signal POS1d and a data signal DATAd based on the first carrier signal, and to generate a position signal POS1u and a data signal DATAu based on the second carrier signal. More specifically, the processing circuit 26d is configured to acquire an unmodulated first carrier signal as the position signal POS1d and an unmodulated second carrier signal as the position signal POS1u. The processing circuit 26d is also configured to acquire a first carrier signal modulated by data to be transmitted to the sensor controller 31 as the data signal DATAd and to acquire a second carrier signal modulated by data to be transmitted to the sensor controller 31 as the data signal DATAu.

[0093] The processing circuit 26d of the active pen 2 in this modified example is configured to start the above-mentioned carrier modulation process at a timing (time t3) determined based on the timing (time t2) of receiving the uplink signal US by the receiving circuit 26c according to a predetermined communication protocol, and to continue performing the carrier modulation process for a period determined by the predetermined communication protocol.

[0094] FIG. 11 shows an example in which time t3 is equal to the start timing of transmission of the position signal POS1, and the carrier modulation process is continued until the end of transmission of the data signal DATA. In this case, the signals generated by the processing circuit 26d through the carrier modulation process are one or more of the position signals POS1d and POS1u, and one or more of the data signals DATAd and DATAu. However, the timing at which the processing circuit 26d starts the carrier modulation process and the period over which the carrier modulation process is continued are not limited to this example. For example, the carrier modulation process may be started simultaneously with the transmission of the position signal POS1 and continued until the end of transmission of the position signal POS1. In this case, the signals generated by the processing circuit 26d through the carrier modulation process are one or more of the position signals POS1d and POS1u. In addition, for example, the carrier modulation process may be started simultaneously with the transmission of the data signal DATA and continued until the end of transmission of the data signal DATA. In this case, the signals generated by the processing circuit 26d through the carrier modulation process are one or more of the data signals DATAd and DATAu. Alternatively, the carrier modulation process may be started or ended at the timing during transmission of the position signal POS1 or the timing during transmission of the data signal DATA.

[0095] The sensor controller 31 according to this modification starts a process of determining whether the carrier signal of the downlink signal DSa received from the active pen 2 is the first carrier signal or the second carrier signal at a timing determined based on the timing at which the transmission of the uplink signal US ends according to the predetermined communication protocol, and sequentially executes this determination process over a period determined by the predetermined communication protocol. Then, based on the determination result, the sensor controller 31 is configured to sequentially determine whether the active pen 2 is in contact with the touch surface 3a. This allows the sensor controller 31 to update the contact state information of the active pen 2 without waiting for the writing pressure value PRE received via pen tip communication or near-field wireless communication.

[0096] As described above, the active pen 2 and position detection system 1 according to this modified example make it possible to transmit contact state information separately from the writing pressure value PRE in the data signal DATA by frequency modulation of the carrier signal of the downlink signal DSa. Of course, the transmission of contact state information according to this modified example (transmission of contact state information by the downlink signal DSa) and the transmission of contact state information according to this embodiment (transmission of contact state information by the downlink signal DSb) may be used together.

[0097] Next, a third embodiment of the present invention will be described in detail. The position detection system 1 according to this embodiment differs from the position detection system 1 according to the second embodiment in that contact state information is transmitted using a plurality of carrier signals with different phases rather than frequencies. The following will focus on the differences and provide a detailed description.

[0098] FIG. 12 illustrates signals transmitted and received between the active pen 2 and the sensor controller 31 that constitute the position detection system 1 of this embodiment. The processing circuit 26d, which failed to receive the uplink signal US in the nth frame and entered the dual transmission mode, performs different processing during the first period P1 shown in the figure and the second period P2 that follows the first period P1. Specifically, during the first period P1, the processing circuit 26d generates a position signal POS2 based on a carrier signal of a predetermined phase. This position signal POS2 is the same as the position signal POS2 obtained without the above-described carrier modulation process. During the second period P2, the processing circuit 26d generates either the position signal POS2d or POS2u by performing the above-described carrier modulation process. The duration of the first period P1 is predetermined by a predetermined communication protocol.

[0099] In this embodiment, the carrier signal (first carrier signal) constituting position signal POS2d is a signal whose phase difference with the carrier signal (third carrier signal) constituting position signal POS2 is a first value. On the other hand, the carrier signal (second carrier signal) constituting position signal POS2u is a signal whose phase difference with the carrier signal (third carrier signal) constituting position signal POS2 is a second value different from the first value. In a typical example, the first value is 0 degrees and the second value is 90 degrees or 180 degrees. However, the first value may be 90 degrees or 180 degrees and the second value may be 0 degrees. Furthermore, both the first value and the second value may be values ​​other than 0 degrees. Note that, considering that a signal whose phase is 180 degrees different from that of the signal transmitted from the pen tip electrode 21 may be transmitted from the user's hand holding the active pen 2, it is more preferable to set the first value or the second value to 90 degrees rather than 180 degrees. However, if the signal transmitted from the user's hand can be rejected by a predetermined palm rejection process that is executed based on the signal reception area, etc., the first value or the second value may be set to 180 degrees.

[0100] The processing circuit 26d determines the state of the active pen 2 based on the latest contact state information it has acquired, and generates a position signal POS2d if the active pen 2 is in a contact state, but generates a position signal POS2d if the active pen 2 is in a hover state, and transmits the generated signal as a downlink signal DSb. As in the second embodiment, the transmission of the position signal POS2d or the position signal POS2u is executed until an uplink signal US is received, or until a predetermined time has elapsed since the last uplink signal US was received.

[0101] The sensor controller 31 according to this embodiment is configured to detect the phase of the carrier signal of the received downlink signal DSb at a predetermined first timing after transmission of the uplink signal US and a second timing after the first timing. The first timing is a timing within a first period P1, and the second timing is a timing within a second period P2. The sensor controller 31 measures the elapsed time from when reception of the downlink signal DSb began, and acquires the period until a time length determined by a predetermined communication protocol has elapsed as the first period P1, and acquires the period after the end of the first period P1 as the second period P2, and sets the first timing and the second timing based on the acquired periods.

[0102] The sensor controller 31 detects the phase of the carrier signal of the downlink signal DSb at each of the first and second timings, and determines whether the active pen 2 is in contact with the touch surface 3a based on the detected phase difference. That is, if the detected phase difference is the first value, it determines the contact state, and if it is the second value, it determines the hover state. This allows the sensor controller 31 to update the contact state information of the active pen 2 without waiting for the pen pressure value PRE received by pen tip communication or near-field wireless communication.

[0103] Here, it is preferable that the sensor controller 31 sets a plurality of second timings and performs the above determination for each second timing, which enables the sensor controller 31 to more frequently determine whether the active pen 2 is in contact with the touch surface 3 a.

[0104] As described above, according to the active pen 2 and position detection system 1 of this embodiment, contact state information can be transmitted by phase modulation of the carrier signal of the downlink signal DSb, and therefore, as in the second embodiment, it is possible to suppress delays in updating of contact state information by the sensor controller 31.

[0105] 13 is a diagram showing signals transmitted and received between the active pen 2 and sensor controller 31 that constitute a position detection system 1 according to a modified example of the present embodiment. The position detection system 1 according to this modified example differs from the position detection system 1 according to the present embodiment in that it uses a downlink signal DSa instead of a downlink signal DSb to transmit contact state information separately from the pen pressure value PRE in the data signal DATA. The following description will focus on these differences.

[0106] The processing circuit 26d according to this modified example is configured to determine the start timings (times t5 and t6) of the first period P1 and the second period P2 at timings determined based on the reception timing (time t4) of the uplink signal US by the receiving circuit 26c according to a predetermined communication protocol.

[0107] 13 shows an example in which time t5 is equal to the start timing of transmission of the position signal POS1 and time t6 is equal to the start timing of transmission of the data signal DATA. In this case, the processing circuit 26d generates the position signal POS1 based on the third carrier signal, while for the data signal DATA, it generates the data signal DATAd based on the first carrier signal in the contact state and generates the data signal DATAu based on the second carrier signal in the hover state. However, the start timings of the first period P1 and the second period P2 determined by the processing circuit 26d are not limited to this example. For example, the start timing of the second period P2 may be set to the timing during transmission of the position signal POS1 or the data signal DATA.

[0108] The sensor controller 31 according to this modification determines the start timings of the first period P1 and the second period P2 based on the timing determined based on the timing of the end of transmission of the uplink signal US according to the predetermined communication protocol. The subsequent processing is the same as the processing performed by the sensor controller 31 according to this embodiment.

[0109] As described above, with the active pen 2 and position detection system 1 according to this modified example, it becomes possible to transmit contact state information separately from the writing pressure value PRE in the data signal DATA by phase modulation of the carrier signal of the downlink signal DSa. Of course, the transmission of contact state information according to this modified example (transmission of contact state information by the downlink signal DSa) and the transmission of contact state information according to this embodiment (transmission of contact state information by the downlink signal DSb) may be used together.

[0110] 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.

[0111] For example, in the above embodiments, the uplink signal US is transmitted from the sensor controller 31 by electrostatic coupling, but the uplink signal US may be transmitted by electromagnetic induction. In this case, it is preferable that the active pen 2 be provided with a coil for receiving the uplink signal US, instead of the ring electrode 22 and stop filter 27.

[0112] Furthermore, in each of the above embodiments, an example has been described in which the downlink signal DSc transmits the local identifier LID, the pen pressure value PRE, the switch information SW, and the error detection code CRC, but the downlink signal DSc need only transmit at least a portion of the data signal transmitted by the active pen 2 to the sensor controller 31, and some of this information may not be transmitted, or other information may be transmitted.

[0113] Furthermore, in the above embodiments, examples have been described in which the ring electrode 22 is used to detect the uplink signal US, but the downlink signal DS may also be transmitted from the ring electrode 22. In one example, the downlink signal DSa may be transmitted from the pen tip electrode 21, and the downlink signal DSb may be transmitted from the ring electrode 22. In this case, the processing circuit 26d may use the pen tip electrode 21 to detect the uplink signal US during transmission of the downlink signal DSb.

[0114] The present invention can also be applied to a case where the transmission and reception of the uplink signal US and the downlink signal DS are performed in units of time slots. For example, a period (blank period) during which noise generated on the display 32 is small is preferably used as the time slot. In this case, multiple time slots are set within the above-mentioned frame.

[0115] Fig. 14 is a diagram showing signals transmitted and received between the active pen 2 and the sensor controller 31 when transmitting and receiving the uplink signal US and the downlink signal DS in units of time slots. This figure shows a case where the processing circuit 26d of the active pen 2 performs carrier modulation processing similar to that of Fig. 10, but the same applies to cases where carrier modulation processing similar to that of Figs. 11 to 13 is performed. As can be seen from Fig. 14, the active pen 2 and the position detection system 1 can preferably perform the above-mentioned carrier modulation processing even when transmitting and receiving the uplink signal US and the downlink signal DS in units of time slots. [Explanation of symbols]

[0116] 1. Position detection system 2 Active Pen 3 Electronic equipment 3a Touch Surface 20 core body 21 Pen tip electrode 22 Ring electrode 23 Pressure Sensor 24 Side Switch 25 Battery 26 Integrated Circuits 26a Boost circuit 26b Transmitting circuit 26c Receiver circuit 26d Processing circuit 27 Stop Filter 28,33 Wireless Communication Department 30 sensors 31 Sensor Controller 32 Display 34 Host Processor COM Commands CRC error detection code DATA Data signal DS, DSa~DSc downlink signal GID Global Identifier LID,NLID Local Identifier POS1,POS2 position signal PRE pressure value SW Switch information US uplink signal

Claims

1. transmitting a signal based on contact state information indicating whether the pen tip is in contact with the touch surface from the pen tip electrode; The pen pressure value, which indicates the pressure applied to the pen tip, is transmitted via short-range wireless communication. pen.

2. When the contact state information indicates that the pen tip is in contact with the touch surface, transmitting a signal based on the contact state information from the pen tip electrode and transmitting the writing pressure value by the near field communication; When the contact state information indicates that the pen tip is not in contact with the touch surface, a signal based on the contact state information is transmitted from the pen tip electrode, but the writing pressure value is not transmitted by the near field communication.

10. The pen of claim 1.

3. In response to receiving an uplink signal from the sensor controller, switching from a mode in which the writing pressure value is transmitted via the short-range wireless communication to a mode in which the writing pressure value is transmitted from the pen tip electrode.

10. The pen of claim 1.

4. The contact state information is 1-bit information.

10. The pen of claim 1.

5. a position signal, which is an unmodulated carrier wave signal, is modulated based on the contact state information, thereby transmitting a signal based on the contact state information from the pen tip electrode; 5. The pen of claim 4.

6. modulating the position signal by any one of frequency modulation, spread spectrum, and phase modulation; 6. A pen according to claim 5.

7. and determining whether the pen tip is in contact with the touch surface based on the writing pressure value, thereby acquiring the contact state information. A pen according to any one of claims 1 to 6.

Images