Active pen and touch device

Abstract

The present invention relates to an active pen and a touch device. The active pen comprises: a transmission circuit connected to a first electrode and a second electrode; and a pen control circuit that performs transmission control of the transmission circuit such that a signal is transmitted in frame units toward the touch device via the first electrode or the second electrode. Each frame includes a first time slot indicating a period of time in which a first signal including first data is transmitted via the first electrode, and a second time slot indicating a period of time in which a second signal including second data is transmitted via the second electrode.

Description

Active Pen and Touch Devices

[0001] The present invention relates to active pen and touch devices.

[0002] Conventionally, a position detection system has been known that is composed of an active electronic pen (hereinafter referred to as an "active pen"), which is a self-powered position indicator, and a touch device including a touch sensor. In this type of system, signals are transmitted and received between the active pen and the touch device to exchange data or synchronize control.

[0003] U.S. Patent No. 5,793,360 discloses a stylus that has an antenna on the tail side opposite to the tip side that transmits pen signals, and is configured to be able to transmit an eraser signal from this antenna. Specifically, this patent document 1 describes that an eraser signal is output when a specific hardware switch operation is received.

[0004] U.S. Pat. No. 5,793,360

[0005] However, with the active pen disclosed in US Pat. No. 5,793,360, for example, the user must perform a switch operation each time the pen function is switched to the eraser function, which reduces usability for the user.

[0006] The present invention has been made in view of the above-mentioned problems, and its object is to provide an active pen and a touch device that can improve usability for the user when switching between multiple types of functions.

[0007] An active pen in a first aspect of the present invention is a pen used in conjunction with a touch device comprising a capacitive touch sensor having a plurality of sensor electrodes arranged in a planar form, and comprises a first electrode, a second electrode provided at a position different from the first electrode, a transmitting circuit connected to the first electrode and the second electrode, and a pen control circuit that controls transmission of the transmitting circuit so as to transmit a signal to the touch device on a frame-by-frame basis via the first electrode or the second electrode, wherein the frame comprises a first time slot indicating a time period during which a first signal including first data is transmitted via the first electrode, and a second time slot indicating a time period during which a second signal including second data is transmitted via the second electrode.

[0008] A touch device in a second aspect of the present invention comprises a capacitive touch sensor having a plurality of sensor electrodes arranged in a planar shape, and a sensor controller that receives signals from an active pen on a frame-by-frame basis via the sensor electrodes, wherein the frames include a first time slot indicating a time period during which a first signal is received, the first signal being generated or modulated by using a first communication parameter, and a second time slot indicating a time period during which a second signal is received, the second signal being generated or modulated by using a second communication parameter, and the sensor controller acquires first data contained in the first signal or second data contained in the second signal through a demodulation process using the first communication parameter and the second communication parameter.

[0009] An active pen in a third aspect of the present invention is a pen used in conjunction with a touch device comprising a capacitive touch sensor having a plurality of sensor electrodes arranged in a planar form, and comprises a housing, a first electrode provided on the tip side of the housing, a second electrode provided on the tail side of the housing, an attitude sensor that outputs a detection signal indicating the attitude of the housing, and a pen controller that switches the connection state between the first electrode and the second electrode in response to the detection signal from the attitude sensor and transmits a signal to the touch device.

[0010] According to the present invention, it is possible to improve usability for the user when switching between a plurality of types of functions.

[0011] 11 is a diagram showing the overall configuration of a position detection system incorporating an active pen common to each embodiment of the present invention. FIG. 12 is a diagram schematically showing the outer shape of an active pen in a first embodiment. FIG. 13 is a block diagram of a pen controller included in the active pen of FIG. 2. FIG. 14 is a functional block diagram related to the pen-side MCU shown in FIG. 3. FIG. 15 is a functional block diagram related to the sensor controller shown in FIG. 1. FIG. 16 is a flowchart showing an example of a frame transmission operation by the pen controller of FIG. 3. FIG. 17 is a diagram showing an example of a data structure included in the frame definition table of FIG. 4. FIG. 18 is a diagram showing an example of a data structure included in the communication information table of FIG. 4. FIG. 19 is a diagram showing an example of a setting result of a slot configuration. FIG. 19 is a diagram schematically showing the outer shape of an active pen in a second embodiment. FIG. 10 is a block diagram of a pen controller included in the active pen of FIG. 10. FIG. 11 is a functional block diagram related to the pen-side MCU shown in FIG. 11. FIG. 18 is a flowchart showing an example of a transmission switching operation by the pen controller of FIG. 11. FIG. 19 is a diagram showing an example of a method of selecting a transmission electrode.

[0012] The active pen and touch device of the present invention will be described with reference to the accompanying drawings. In each drawing, the same components are denoted by the same reference numerals whenever possible, and redundant explanations will be omitted. Furthermore, the term "part" may be replaced with other terms, such as unit, module, device, or element.

[0013] 1 is a diagram showing the overall configuration of a position detection system 10 incorporating an active pen 12 common to all embodiments of the present invention. The position detection system 10 is basically composed of the active pen 12 and a touch device 14 used together with the active pen 12.

[0014] The active pen 12 is a pen-type pointing device configured to be capable of one-way or two-way communication with the touch device 14. In this embodiment, the active pen 12 is an "active electrostatic coupling (AES) type" or "capacitive type" stylus that actively generates a signal from electrical energy stored in the active pen 12 and transmits this signal to the touch device 14 as a downlink signal DS.

[0015] The touch device 14 is a computer owned by a user, and may be, for example, a tablet terminal with or without a display function, a smartphone, a personal computer, etc. Alternatively, the touch device 14 may be [1] a device installed in a building (for example, a home appliance, furniture, fixtures, etc.), or [2] a device that constitutes part of a building (for example, a wall, floor, window, pillar, etc.).

[0016] The touch device 14 includes a memory, a communication module, or a display panel (none of which are shown) in addition to the touch sensor 16, the sensor controller 18, and the host processor 20. The host processor 20 uses the position data sequentially output from the sensor controller 18 to perform processes such as generating digital ink and displaying a pointer.

[0017] The touch sensor 16 is a capacitance-type (more specifically, mutual capacitance-type or self-capacitance-type) position sensor having a plurality of sensor electrodes 16x, 16y arranged in a plane. The active pen 12 and the touch sensor 16 are capacitively coupled to each other via a capacitance Cpen. The user's finger F and the touch sensor 16 are also capacitively coupled to each other via a capacitance Cfin.

[0018] Specifically, the touch sensor 16 includes a plurality of sensor electrodes 16x for detecting a position on the x-axis and a plurality of sensor electrodes 16y for detecting a position on the y-axis. The sensor electrodes 16x extend in the y-direction and are arranged at equal intervals along the x-direction. The sensor electrodes 16y extend in the x-direction and are arranged at equal intervals along the y-direction. The x- and y-directions shown in this figure correspond to the x- and y-axes of a Cartesian coordinate system defined within the sensor area.

[0019] Each of the sensor electrodes 16x, 16y may be made of a transparent conductive material including ITO (Indium Tin Oxide), or may be made of a wire mesh sensor. The touch sensor 16 may be a built-in sensor (further classified as an on-cell or in-cell sensor) that is integrated with a display panel (not shown), or an external sensor (or an out-cell sensor) that is attached to the display panel from the outside.

[0020] The sensor controller 18 is a control circuit that executes a detection function of the active pen 12 (hereinafter also referred to as the "pen detection function") and a detection function of a passive pointer (a finger F in the example of FIG. 1) (hereinafter also referred to as the "touch detection function") via the touch sensor 16. While executing the pen detection function, the sensor controller 18 detects the pen position of the active pen 12 by transmitting an uplink signal US to the active pen 12 and receiving a downlink signal DS from the active pen 12. While executing the touch detection function, the sensor controller 18 detects the touch position of the finger F by transmitting a finger detection signal FDS and receiving the finger detection signal FDS that involves a change in capacitance as the finger F approaches.

[0021] First Embodiment First, a position detection system 10A according to a first embodiment will be described with reference to Figures 2 to 9. The position detection system 10A corresponds to one aspect of the position detection system 10 shown in Figure 1. This position detection system 10A includes an active pen 12A and a touch device 14.

[0022] 2 is a diagram showing a schematic external view of the active pen 12A according to the first embodiment. The active pen 12A includes a cylindrical housing 22 capable of housing components. A tip electrode 24 (corresponding to a "first electrode") and a ring electrode 26 are provided at the tip end (hereinafter also referred to as the "tip side") of the housing 22.

[0023] The tip electrode 24 and the ring electrode 26 are each made of or contain a conductive material such as metal. Specifically, the tip electrode 24 is a conical electrode attached to the tip of the core 28. The ring electrode 26 is a tapered annular electrode whose diameter gradually decreases toward the tip.

[0024] A sensor (hereinafter referred to as tip-side sensor 30) that detects the presence or absence of contact with the tip side or the amount of writing pressure acting on the tip side is connected to the base end of the lead 28. The detection method used for the tip-side sensor 30 may be, for example, a capacitance method, a resistive film method, a piezoelectric element method, an optical method, or a MEMS (Micro Electro-Mechanical System) method.

[0025] A tail electrode 32 (corresponding to a "second electrode") is provided at the rear end (hereinafter also referred to as the "tail side") of the housing 22. Hereinafter, one or more electrodes of the active pen 12A, i.e., the tip electrode 24, the ring electrode 26, and the tail electrode 32, may be collectively referred to as the "pen electrodes."

[0026] The tail electrode 32 is made of or contains a conductive material such as metal. A sensor (hereinafter referred to as a tail-side sensor 34) that detects the presence or absence of contact with the tail side or the amount of writing pressure acting on the tail side is connected to the base end of the tail electrode 32. The tail-side sensor 34 (corresponding to a "contact sensor") may use a detection method such as a capacitance method, a resistive film method, a piezoelectric element method, an optical method, a strain gauge method, or a MEMS method.

[0027] A pen controller 36, which may be composed of a single board or multiple boards, is provided inside the housing 22. The pen controller 36 includes an electric circuit for operating the active pen 12.

[0028] <Block Diagram of Pen Controller 36> Figure 3 is a block diagram of the pen controller 36 included in the active pen 12A of Figure 2. In addition to the tip electrode 24, ring electrode 26, tail electrode 32, tip side sensor 30, and tail side sensor 34 (Figure 2) described above, a power supply module 40 capable of supplying power is connected to this pen controller 36. The power supply module 40 is composed of a power storage unit 42 and a power management integrated circuit (hereinafter referred to as PMIC 44).

[0029] The power storage unit 42 is composed of, for example, a battery or a capacitor, and supplies driving power to electronic components or electronic elements on the pen controller 36. The PMIC 44 is an integrated circuit that monitors the state of the power storage unit 42 and supplies power to the pen controller 36.

[0030] The pen controller 36 is composed of a microcontroller unit (hereinafter referred to as the "pen side MCU 50", which corresponds to the "pen control circuit"), a first switch 52, a second switch 54, a pen side receiving circuit 56, and a pen side transmitting circuit 58 (which corresponds to the "transmitting circuit").

[0031] The pen-side MCU 50 is an electronic circuit unit that performs overall control over each part of the active pen 12 A. The pen-side MCU 50 is configured to receive an uplink signal US from the touch device 14 by performing desired reception control on the pen-side receiving circuit 56. The pen-side MCU 50 is configured to perform desired digital signal processing on the data supplied from the pen-side receiving circuit 56, and to transmit a downlink signal DS to the touch device 14 by performing desired transmission control on the pen-side transmitting circuit 58.

[0032] The first switch 52 is a switch element configured so that a common terminal is connected to one of the E1, E2, and E3 terminals. The common terminal of the first switch 52 is connected to the common terminal of the second switch 54, the E1 terminal is connected to the tip electrode 24, the E2 terminal is connected to the tail electrode 32, and the E3 terminal is connected to the ring electrode 26. The pen-side MCU 50 supplies a switch control signal SWC1 to the first switch 52 to perform switching control, thereby selecting either [1] a pen electrode used for reception (hereinafter also referred to as a "receiving electrode") or [2] a pen electrode used for transmission (hereinafter also referred to as a "transmitting electrode").

[0033] The second switch 54 is a switch element configured so that its common terminal is connected to either the R terminal or the T terminal. The common terminal of the second switch 54 is connected to the common terminal of the first switch 52, its R terminal to the input terminal of the pen-side receiving circuit 56, and its T terminal to the output terminal of the pen-side transmitting circuit 58. The pen-side MCU 50 supplies a switch control signal SWC2 to the second switch 54 to perform switching control, thereby selectively receiving the uplink signal US and transmitting the downlink signal DS.

[0034] The pen-side receiving circuit 56 is a circuit that demodulates the uplink signal US induced in the receiving electrode and outputs the demodulated data to the pen-side MCU 50. The ground terminal of the pen-side receiving circuit 56 is grounded (or connected to ground) to the housing 22 of the active pen 12A. Specifically, the pen-side receiving circuit 56 is configured to include a waveform regenerator and a correlation calculator.

[0035] The waveform regenerator binarizes the voltage level induced in the receiving electrode using a clock of a predetermined rate, shapes it into a binary string of positive and negative polarity values ​​(i.e., a chip string), and outputs it. This clock frequency is set, for example, to an integer multiple of the chip rate of the spreading code. The correlation calculator stores the chip string from the waveform regenerator in a register and performs correlation calculations with the spreading code while sequentially shifting it with the clock. This decodes the chip string contained in the uplink signal US.

[0036] The pen-side transmitting circuit 58 is a circuit that generates the downlink signal DS under the control of the pen-side MCU 50. When the downlink signal DS is a "position signal," the pen-side transmitting circuit 58 outputs an unmodulated carrier signal, and when the downlink signal DS is a "data signal," the pen-side transmitting circuit 58 modulates the carrier signal using transmission data and outputs the modulated carrier signal. Specifically, the pen-side transmitting circuit 58 is configured to include a modulator and a boost circuit.

[0037] The modulator generates a carrier signal such as a square wave or triangular wave, and outputs it modulated or as is under the control of the pen-side MCU 50. When transmitting a burst signal, the modulator outputs the carrier signal as is without modulating it, in accordance with instructions from the pen-side MCU 50. On the other hand, when transmitting a data signal, the modulator modulates the carrier signal (OOK (On-Off-keying), PSK (Pre-Shared Key), etc.) using data supplied from the pen-side MCU 50, and outputs the resulting modulated signal. The boost circuit generates a downlink signal DS by boosting the output signal supplied from the modulator to a certain amplitude. The downlink signal DS generated by the boost circuit is sent to the outside from the transmitting electrode via the second switch 54 and the first switch 52.

[0038] Fig. 4 is a functional block diagram of the pen-side MCU 50 shown in Fig. 3. The tip-side sensor 30, the tail-side sensor 34, the pen-side receiving circuit 56, and the pen-side transmitting circuit 58 are connected to the pen-side MCU 50. The pen-side MCU 50 is configured to include a data acquisition unit 60, a data generation unit 62, and a communication control unit 64.

[0039] The data acquisition unit 60 acquires the demodulated data (i.e., received data) through the pen-side receiving circuit 56. In this way, data from the touch device 14 is acquired.

[0040] The data generation unit 62 generates data to be supplied to the touch device 14 (i.e., transmission data) and outputs it to the pen-side transmission circuit 58. For example, when transmitting and receiving data in frame units, the data generation unit 62 generates and outputs the transmission data in accordance with slot configuration information from the communication control unit 64. Here, a "frame" is a time unit (or cycle) for exchanging data with the touch device 14, and is composed of one or more time slots. This "time slot" corresponds to a time period allocated for the execution of an event.

[0041] The communication control unit 64 controls the reception of the uplink signal US and the transmission of the downlink signal DS. For example, when transmitting the downlink signal DS, the communication control unit 64 outputs switch control signals SWC1 and SWC2, and supplies slot configuration information (described later) to the data generation unit 62 and communication parameters (described later) to the pen-side transmission circuit 58. The communication control unit 64 holds a frame definition table T1 and a communication information table T2.

[0042] The frame definition table T1 includes information for defining the slot configuration within a frame (hereinafter referred to as "slot configuration information"). Examples of slot configuration information include: [1] the number and identification information of the time slots that make up the frame; [2] "event information" indicating the type of event corresponding to the time slot; [3] "time information" regarding the time of the time slot; or [4] "electrode information" regarding the transmitting electrode or receiving electrode corresponding to the time slot. The number or type of frame definition table T1 may be one or more.

[0043] Examples of events include [1] reception of an uplink signal US, [2] transmission of a downlink signal DS, [3] no-signal state, or [4] touch detection. Examples of time information include the start time, end time, or duration of a time slot. In the example of Fig. 2, the electrode information is identification information of the pen electrode (or electrode ID (Identification)).

[0044] The communication information table T2 includes information related to the transmission of the downlink signal DS (hereinafter referred to as "transmission information"). Examples of the transmission information include [1] "electrode information" related to the transmitting electrode, [2] "communication parameters" used in the transmission process, or [3] "signal type" indicating the type of signal. The number or type of communication information table T2 may be one or more.

[0045] Examples of communication parameters include [1] carrier frequency, [2] type of modulation method, [3] transmission voltage, or [4] whether or not voltage is boosted. Examples of signal types include [1] a "pen signal" indicating an intention to write, [2] an "erase signal" indicating an intention to erase, or [3] a "marking signal" indicating an intention to mark. Communication parameters may have different values ​​depending on the transmission electrode or signal type. For example, with regard to the modulation method, "OOK" may be selected for the tip electrode 24, and "PSK" may be selected for the tail electrode 32. Furthermore, with regard to the carrier frequency, F1 [kHz] may be selected for the pen signal, F2 [kHz] for the erase signal, and F3 [kHz] for the marking signal.

[0046] The communication control unit 64 performs transmission control to generate or modulate a carrier signal using first communication parameters when transmitting a first signal in a first time slot, while performing transmission control to generate or modulate a carrier signal using second communication parameters different from the first communication parameters when transmitting a second signal in a second time slot.

[0047] The above-mentioned "first time slot" refers to a time period during which a first signal is transmitted via the tip electrode 24. Here, the "first signal" includes data (hereinafter referred to as "first data") corresponding to the tip electrode 24. Examples of the first data include identification information of the tip electrode 24, or a detection value by the tip-side sensor 30.

[0048] The above-mentioned "second time slot" refers to a time period during which a second signal is transmitted via the tail electrode 32. Here, the "second signal" includes data (hereinafter, "second data") corresponding to the tail electrode 32. Examples of the second data include identification information of the tail electrode 32, or a detection value by the tail-side sensor 34.

[0049] The communication control unit 64 may change the configuration of the time slots within the frame depending on the reception status of the uplink signal US. For example, when the tip electrode 24 or the ring electrode 26 is selected as the receiving electrode, the communication control unit 64 may increase the number or duration of the first time slots and decrease the number or duration of the second time slots as the reception strength of the uplink signal US increases. Alternatively, when the tail electrode 32 is selected as the receiving electrode, the communication control unit 64 may increase the number or duration of the second time slots and decrease the number or duration of the first time slots as the reception strength of the uplink signal US increases.

[0050] The communication control unit 64 may change the configuration of time slots within a frame depending on the content of received data identified from the uplink signal US. For example, if the received data includes an identifier from the frame definition table T1 or the communication information table T2, the communication control unit 64 may select slot configuration information corresponding to the identifier obtained through reception and control transmission according to the corresponding slot configuration information. Also, if the received data includes slot configuration information, the communication control unit 64 may control transmission according to the slot configuration information obtained through reception.

[0051] The communication control unit 64 may switch between transmitting and not transmitting the downlink signal DS in accordance with the detection signal from the tail side sensor 34. For example, the communication control unit 64 may perform control so that the downlink signal DS is transmitted from the tip electrode 24 or the ring electrode 26, regardless of whether or not contact on the tail side is detected by the tail side sensor 34. Alternatively, the communication control unit 64 may perform control so that the downlink signal DS is transmitted from the tail electrode 32 only while contact on the tail side is detected by the tail side sensor 34.

[0052] <Functional Block Diagram of Sensor Controller 18> Fig. 5 is a functional block diagram relating to the sensor controller 18 shown in Fig. 1. The sensor controller 18 is configured to include a position detection unit 80 and an output processing unit 82.

[0053] The position detection unit 80 detects the position of the active pen 12A or a passive pointer (for example, a user's finger F) according to a plurality of types of operation modes. The position detection unit 80 performs a drive operation on the touch sensor 16 according to the selected operation mode. Examples of the drive operation include [1] an operation for transmitting an uplink signal US, [2] an operation for receiving a downlink signal DS, [3] an operation for calculating the angle of the active pen 12B, or [4] various operations related to the scanning operation of the touch sensor 16.

[0054] Specifically, the position detection unit 80 includes a scan control unit 84 , a signal transmission unit 86 , a signal acquisition unit 88 , a touch detection unit 90 , and a pen detection unit 92 .

[0055] The scan control unit 84 repeatedly executes multiple types of scan processing in a time-division manner via the touch sensor 16. The multiple types of scan processing include [1] a "touch scan" for detecting a passive pointer (e.g., a finger F) that does not transmit a signal, and [2] a "pen scan" for detecting an active pen 12A that transmits a downlink signal DS. The touch scan and the pen scan may be executed at a ratio of 1:1 or at a ratio of n:m (n≠m).

[0056] The above-described touch scan is performed to detect changes in capacitance between the sensor electrodes 16x and 16y. This touch scan may be, for example, [1] a scan based on a "mutual capacitance method" in which a finger detection signal FDS is transmitted from the sensor electrode 16x and received by the sensor electrode 16y to detect changes in mutual capacitance between the sensor electrodes 16x and 16y, or [2] a scan based on a "self-capacitance method" in which changes in capacitance between the sensor electrodes 16x and 16y are detected.

[0057] When transmitting and receiving data in frame units, the scan control unit 84 refers to the frame definition table T1 or the communication information table T2 and performs scanning of the touch sensor 16 in accordance with the specified slot configuration information. For example, prior to receiving the downlink signal DS, the scan control unit 84 supplies the signal acquisition unit 88 with communication parameters used for demodulating the data.

[0058] The signal transmitting unit 86 transmits a desired signal for performing a touch scan or a pen scan from the sensor electrodes 16x, 16y in accordance with transmission control by the scan control unit 84. During execution of a touch scan, the signal transmitting unit 86 generates a finger detection signal FDS for detecting a finger F, and outputs and transmits this finger detection signal FDS to a transmission electrode (here, one or more sensor electrodes 16x). During execution of a pen scan, the signal transmitting unit 86 generates an uplink signal US for detecting the active pen 12A, and outputs and transmits this uplink signal US to a transmission electrode (here, one or more sensor electrodes 16x, 16y).

[0059] The uplink signal US may include data for specifying the slot configuration within the frame (hereinafter, "configuration specifying data"). Examples of the configuration specifying data include [1] a frame definition table T1, [2] a communication information table T2, [3] slot configuration information, or [4] identification information related to these pieces of information.

[0060] The signal acquisition unit 88 receives or acquires desired signals for performing touch scanning or pen scanning from the sensor electrodes 16x, 16y in accordance with reception control by the scan control unit 84. During execution of touch scanning, the signal acquisition unit 88 receives, via receiving electrodes (here, one or more sensor electrodes 16y), a finger detection signal FDS from the transmitting electrode, and acquires a detection signal (or a first detection signal) for detecting the presence or position of a finger F. During execution of pen scanning, the signal acquisition unit 88 receives, via receiving electrodes (here, one or more sensor electrodes 16x, 16y), a downlink signal DS from the active pen 12B, and acquires a detection signal (or a second detection signal) for detecting the presence or position of the active pen 12A.

[0061] When receiving a downlink signal DS, the signal acquirer 88 performs reception control to demodulate the data using the first communication parameters and / or the second communication parameters. For example, if the signal acquirer 88 can demodulate the data using the first communication parameters, it determines that the downlink signal DS is the "first signal" transmitted from the tip electrode 24. On the other hand, if the signal acquirer 88 can demodulate the data using the second communication parameters, it determines that the downlink signal DS is the "second signal" transmitted from the tail electrode 32.

[0062] The touch detection unit 90 detects the presence or position of a passive pointer (hereinafter also collectively referred to as "touch position") by applying various signal processing to the first detection signal acquired by the signal acquisition unit 88. This signal processing includes: [1] "threshold processing" that detects the presence or absence of a finger F from the magnitude relationship between the signal value for each position indicated by the signal distribution and a threshold value; [2] "identification processing" that identifies the type of touch (e.g., finger F, palm, or other object) based on the size or shape of the area detected by the threshold processing; and [3] "position calculation processing" that calculates the touch position by performing an interpolation or approximation operation on the signal distribution.

[0063] The pen detection unit 92 detects the presence or absence or position of the active pen 12A (hereinafter collectively referred to as "pen position") by performing various signal processing on the second detection signal acquired by the signal acquisition unit 88. This signal processing includes [1] "threshold processing" that detects the presence or absence of the active pen 12A from the magnitude relationship between the signal level at each position indicated by the signal distribution and a threshold, and [2] "position calculation processing" that detects the pen position by performing an interpolation or approximation operation on the signal distribution.

[0064] The output processing unit 82 generates position information including the pen position or touch position calculated by the position detection unit 80, and then outputs data including the position information to the host processor 20 (FIG. 1). The output processing unit 82 may output data at a predetermined cycle (e.g., 120 Hz). In addition to the position information of the active pen 12A, this data may also include: [1] information provided by the active pen 12A (e.g., pen ID, writing pressure, pen switch on / off information, etc.); [2] information calculated from the position information (e.g., tilt angle, azimuth angle, speed, acceleration); or [3] identification information of the currently executing operation mode.

[0065] <Description of Frame Transmission Operation> The position detection system 10A in the first embodiment is configured as described above. Next, the operation of the position detection system 10A will be described with reference to Figures 6 to 9. Figure 6 is a flowchart showing an example of a frame transmission operation by the pen controller 36 of Figure 3.

[0066] 6, the pen-side MCU 50 of the pen controller 36 checks whether the timing to transmit the downlink signal DS has arrived. If the timing has not yet arrived (step SP10: NO), the pen-side MCU 50 remains in step SP10 until the timing arrives. If the timing has arrived (step SP10: YES), the pen-side MCU 50 proceeds to the next step, SP12.

[0067] In step SP12, the pen-side MCU 50 (more specifically, the communication control unit 64) acquires various information required to set the slot configuration within the frame, such as the frame definition table T1 and the communication information table T2.

[0068] Fig. 7 is a diagram showing an example of the data structure of the frame definition table T1 of Fig. 4. This frame definition table T1 shows the correspondence relationship between [1] a "slot number" for identifying a time slot and [2] "electrode information" for specifying a transmitting electrode. In the example of Fig. 7, "transmission from tip electrode 24" is set in the 0th time slot, "transmission from ring electrode 26" in the 1st time slot, "non-transmission" in the 2nd time slot, and "transmission from tail electrode 32" in the (n-1)th time slot.

[0069] Fig. 8 is a diagram showing an example of the data structure of the communication information table T2 of Fig. 4. This communication information table T2 shows the correspondence relationship between [1] "electrode information" for identifying the transmitting electrode, [2] "communication parameters" used for transmission, and [3] "signal type" of the downlink signal DS. In the example of Fig. 8, the table is set so that a pen signal is transmitted from the tip electrode 24 using "Param-1," a pen signal is transmitted from the ring electrode 26 using "Param-2," and an eraser signal is transmitted from the tail electrode 32 using "Param-3."

[0070] In step SP14 of FIG. 6, the communication control unit 64 refers to the various information acquired in step SP12 and sets the slot configuration within the frame.

[0071] Fig. 9 is a diagram showing an example of the result of setting the slot configuration. In the example of Fig. 9, one fixed time slot and n variable time slots (n is a natural number) are provided within one frame. "Uplink" corresponds to the fixed time slot indicating the time period during which the uplink signal US is received. Furthermore, "0" to "n-1" correspond to the variable time slots indicating the time period during which an event is executed.

[0072] 6, the pen controller 36 transmits the downlink signal DS in accordance with the slot configuration set in step SP 14. This transmission operation includes [1] a transmission signal generation operation by the data generation unit 62 (step SP16A), and [2] a switching control operation by the communication control unit 64 (step SP16B). Thereafter, the pen controller 36 returns to step SP10 and sequentially executes steps SP10 to SP16.

[0073] In this way, the pen controller 36 performs communication with the touch device 14 (that is, communication in the AES format) by repeatedly executing steps SP10 to SP16 in FIG.

[0074] The touch device 14 receives the downlink signal DS from the active pen 12A on a frame-by-frame basis. Specifically, when data is acquired through a demodulation process using the first communication parameters, the signal acquisition unit 88 in Fig. 5 determines that the downlink signal DS is the "first signal" transmitted from the tip electrode 24. On the other hand, when data is acquired through a demodulation process using the second communication parameters, the signal acquisition unit 88 determines that the downlink signal DS is the "second signal" transmitted from the tail electrode 32.

[0075] Summary of First Embodiment As described above, the active pen 12A in the first embodiment is used together with the touch device 14 configured to include a capacitive touch sensor 16 formed by arranging a plurality of sensor electrodes 16x, 16y in a planar manner. The active pen 12A includes a first electrode (here, the tip electrode 24), a second electrode (here, the tail electrode 32) provided at a position different from the tip electrode 24, a transmission circuit (here, the pen-side transmission circuit 58) connected to the tip electrode 24 and the tail electrode 32, and a pen control circuit (here, the pen-side MCU 50) that performs transmission control on the pen-side transmission circuit 58 so as to transmit a signal to the touch device 14 on a frame-by-frame basis via the tip electrode 24 or the tail electrode 32.

[0076] The frame is configured to include a first time slot indicating a time period during which a first signal including first data is transmitted via the tip electrode 24, and a second time slot indicating a time period during which a second signal including second data is transmitted via the tail electrode 32. With this configuration, signals can be transmitted from both the tip electrode 24 and the tail electrode 32 within one frame, eliminating the need for a user operation to switch between the tip electrode 24 and the tail electrode 32. This improves usability for the user when switching between multiple functions of the active pen 12A.

[0077] Furthermore, the pen-side MCU 50 may perform transmission control such that, when transmitting a first signal, it generates or modulates a carrier signal using first communication parameters, and, when transmitting a second signal, it generates or modulates the carrier signal using second communication parameters different from the first communication parameters. This allows the touch device 14 to determine whether the received downlink signal DS is the first signal or the second signal, depending on whether the demodulation process is successful.

[0078] Furthermore, the pen-side MCU 50 may change the configuration of the first time slot or the second time slot within the frame depending on the reception state of a signal from an external device (here, the touch device 14) or the content of received data identified from the signal. This allows data to be exchanged with the touch device 14 in various time configurations.

[0079] Furthermore, when the first electrode is the tip electrode 24 provided on the tip side and the second electrode is the tail electrode 32 provided on the tail side, the pen-side MCU 50 may stop transmitting the second transmission signal while no contact is detected by a contact sensor (here, the tail-side sensor 34) that detects contact with the tail side. This makes it possible to prevent an erasure operation against the user's intention that would be caused by transmitting the eraser signal. In particular, when the tail electrode 32 is larger in size than the tip electrode 24, the strength of the eraser signal tends to be greater, so the effect of suppressing the erasure operation becomes more pronounced.

[0080] The touch device 14 in the first embodiment includes a capacitive touch sensor 16 having a plurality of sensor electrodes 16x, 16y arranged in a plane, and a sensor controller 18 that receives a signal from the active pen 12A on a frame-by-frame basis via the sensor electrodes 16x, 16y. A frame includes a first time slot indicating a time period during which a first signal formed by generating or modulating a carrier signal using a first communication parameter is received, and a second time slot indicating a time period during which a second signal formed by generating or modulating a carrier signal using a second communication parameter is received.

[0081] The sensor controller 18 acquires the first data contained in the first signal or the second data contained in the second signal through a demodulation process using the first communication parameter and the second communication parameter. This configuration allows the first signal and the second signal to be received within a single frame, eliminating the need for a user operation to switch between signals. This improves usability for the user when switching between multiple functions of the active pen 12A.

[0082] Furthermore, if the active pen 12A is configured to include a first electrode (here, the tip electrode 24) and a second electrode (here, the tail electrode 32) provided at a position different from that of the tip electrode 24, the sensor controller 18 may determine that the signal is from the tip electrode 24 if it is able to acquire first data through a demodulation process using the first communication parameters, and may determine that the signal is from the tail electrode 32 if it is able to acquire second data through a demodulation process using the second communication parameters. This makes it possible to determine the type of signal from the active pen 12A based on whether the demodulation process was successful, even if the slot configuration within the frame is unknown.

[0083] 3, transmission and reception are enabled via each pen electrode by switching the first switch 52 and the second switch 54, but the mode of transmission and reception is not limited to this. For example, the tip electrode 24 and the ring electrode 26 may be configured to enable both transmission and reception, while the tail electrode 32 may be configured to enable only transmission.

[0084] 3, the pen controller 36 is an integrated circuit having a plurality of output terminals for connection to the respective pen electrodes, but the circuit configuration is not limited to this example. For example, the integrated circuit may have a shared output terminal for transmitting signals from the tip electrode 24 and the ring electrode 26, and a dedicated output terminal for transmitting signals from the tail electrode 32. Alternatively, the integrated circuit may have an output terminal common to the plurality of pen electrodes, and an output switch for switching the connection destination of the output terminal may be provided external to the integrated circuit.

[0085] 7, the slot numbers and the transmitting electrodes are associated with each other in a 1:1 relationship, but the association may be 1:n (n≧2). For example, slot number "0" may be associated with three transmitting electrodes (i.e., the tip electrode 24, the ring electrode 26, and the tail electrode 32). In this case, by changing the communication parameters for each transmitting electrode, the touch device 14 can determine the source of the downlink signal DS according to the values ​​of the communication parameters used in the demodulation process.

[0086] In the first embodiment described above, an example was given in which the first electrode is the tip electrode 24 and the second electrode is the tail electrode 32, but the combination is not limited to this. For example, [1] the first electrode may be the tip electrode 24 and the second electrode may be the ring electrode 26, or [2] the first electrode may be the ring electrode 26 and the second electrode may be the tail electrode 32.

[0087] Second Embodiment Next, a position detection system 10B according to a second embodiment will be described with reference to Figures 10 to 14. The position detection system 10B corresponds to one aspect of the position detection system 10 shown in Figure 1. This position detection system 10B includes an active pen 12B and a touch device 14.

[0088] <Device Configuration of Active Pen 12B> Figure 10 is a diagram schematically showing the outer shape of an active pen 12B in the second embodiment. Similar to the first embodiment (active pen 12A in Figure 2), this active pen 12B is configured to include a housing 22, a tip electrode 24, a ring electrode 26, a core 28, a tip-side sensor 30, a tail electrode 32, and a tail-side sensor 34. Inside the housing 22, there are provided a pen controller 100 having a circuit configuration different from that of the first embodiment, and a gyro sensor 102 (corresponding to an "attitude sensor").

[0089] <Block Diagram of Pen Controller 100> Figure 11 is a block diagram of the pen controller 100 included in the active pen 12B of Figure 10. This pen controller 100 is configured to include an integrated circuit 103 such as an ASIC (Application Specific Integrated Circuit). In addition to the power supply module 40 (Figure 3), a gyro sensor 102 and a first switch 104 (corresponding to an "output switch") are each connected to this integrated circuit 103. For ease of explanation, the ring electrode 26 is not shown.

[0090] The gyro sensor 102 is configured to be able to measure angular velocity along three axes and outputs a detection signal indicating the attitude of the active pen 12B (for example, yaw angle, roll angle, pitch angle, azimuth angle, tilt angle, etc.).

[0091] The first switch 104 is a switch element configured such that a common terminal is connected to either the E1 terminal or the E2 terminal. The common terminal of the first switch 104 is connected to a common terminal of the pen controller 100 (more specifically, the second switch 108), the E1 terminal is connected to the tip electrode 24, and the E2 terminal is connected to the tail electrode 32. The pen controller 100 (more specifically, the pen-side MCU 106) supplies a switch control signal SWC1 to the first switch 104 to perform switching control, thereby selecting the tip electrode 24 or the tail electrode 32.

[0092] In addition to the pen side receiving circuit 56 and the pen side transmitting circuit 58, the integrated circuit 103 is further provided with a pen side MCU 106 that operates differently from the pen side MCU 50 in FIG. 3 in the first embodiment, and a second switch 108.

[0093] The pen-side MCU 106 (corresponding to a "pen control circuit") is an electronic circuit unit that performs overall control over each part of the active pen 12B. The pen-side MCU 106 is configured to be able to receive an uplink signal US from the touch device 14 by performing desired reception control on the pen-side receiving circuit 56. The pen-side MCU 106 is configured to be able to transmit a downlink signal DS to the touch device 14 by performing desired digital signal processing on the data supplied from the pen-side receiving circuit 56 and by performing desired transmission control on the pen-side transmitting circuit 58.

[0094] The second switch 108 is a switch element configured so that its common terminal is connected to either the R terminal or the T terminal. The common terminal of the second switch 108 is connected to the common terminal of the first switch 104, its R terminal is connected to the input terminal of the pen-side receiving circuit 56, and its T terminal is connected to the output terminal of the pen-side transmitting circuit 58. The pen-side MCU 106 supplies a switch control signal SWC2 to the second switch 108 to perform switching control, thereby selectively receiving an uplink signal US and transmitting a downlink signal DS.

[0095] <Functional Block Diagram> Figure 12 is a functional block diagram relating to the pen side MCU 106 shown in Figure 11. In addition to the data acquisition unit 60 and the data generation unit 62, the pen side MCU 106 further includes a communication control unit 110 whose operation differs from that of the first embodiment. In addition to the pen side receiving circuit 56 and the pen side transmitting circuit 58, a gyro sensor 102 is also connected to the pen side MCU 106.

[0096] The communication control unit 110 controls the reception of the uplink signal US and the transmission of the downlink signal DS. For example, when transmitting the downlink signal DS, the communication control unit 110 outputs switch control signals SWC1 and SWC2, and supplies slot configuration information to the data generation unit 62 and communication parameters to the pen-side transmission circuit 58. As in the first embodiment ( FIG. 4 ), the communication control unit 110 holds a frame definition table T1 and a communication information table T2.

[0097] When transmitting a first signal in a first time slot, the communication control unit 110 performs transmission control to generate or modulate a carrier signal using a first communication parameter. On the other hand, when transmitting a second signal in a second time slot, the communication control unit 110 performs transmission control to generate or modulate a carrier signal using a second communication parameter. Note that the second communication parameter may have the same value as the first communication parameter, or may have a different value.

[0098] The communication control unit 110 may switch the first switch 104 or the second switch 108 in response to a detection signal from the gyro sensor 102. For example, when the chip electrode 24 faces downward relative to the horizontal, the communication control unit 110 connects the integrated circuit 103 to the chip electrode 24 and performs transmission control to transmit a downlink signal DS via the chip electrode 24. On the other hand, when the chip electrode 24 faces upward relative to the horizontal, the communication control unit 110 connects the integrated circuit 103 to the tail electrode 32 and performs transmission control to transmit a downlink signal DS via the tail electrode 32. Note that the threshold value of the tilt angle θ is not limited to the horizontal state (θ = 0°) and can take various values.

[0099] <Description of Transmission Switching Operation> The position detection system 10B in the second embodiment is configured as described above. Next, the operation of the position detection system 10B will be described with reference to Fig. 13 and Fig. 14. Fig. 13 is a flowchart showing an example of the transmission switching operation by the pen controller 100 of Fig. 11.

[0100] 13, the pen-side MCU 106 of the pen controller 100 checks whether the timing to transmit the downlink signal DS has arrived. If the timing has not yet arrived (step SP20: NO), the pen-side MCU 106 remains in step SP20 until the timing arrives. If the timing has arrived (step SP20: YES), the pen-side MCU 106 proceeds to the next step, SP22.

[0101] In step SP22, the pen-side MCU 106 (more specifically, the communication control unit 110) sets the slot configuration within the frame in the same manner as in the first embodiment (step SP14 in FIG. 5).

[0102] In step SP24, the communication control unit 110 acquires from the gyro sensor 102 a detection signal indicating the three-dimensional orientation of the active pen 12B.

[0103] In step SP26, the communication control unit 110 selects a transmission electrode from among the plurality of pen electrodes based on the detection signal acquired in step SP24.

[0104] FIG. 14 is a diagram showing an example of a method for selecting a transmitting electrode. The X and Y directions indicate the "horizontal direction," and the Z direction indicates the "vertical direction." Orientations P1 and P2 are arrows that schematically indicate the orientation of the active pen 12B. The arrowhead indicates the "tip side," and the circle on the arrow indicates the "tail side." In the example of FIG. 14, an inclination angle θ is defined with the horizontal state as the reference (θ = 0°).

[0105] When the tilt angle is θ1=225°, the active pen 12B has an orientation P1 in which the tip side faces diagonally downward. In this case, the tip electrode 24 is estimated to be on the near side of the touch device 14, and therefore the tip electrode 24 is selected as the transmitting electrode. When the tilt angle is θ2=150°, the active pen 12B has an orientation P2 in which the tip side faces diagonally upward. In this case, the tail electrode 32 is estimated to be on the near side of the touch device 14, and therefore the tail electrode 32 is selected as the transmitting electrode.

[0106] 13 , the communication control unit 110 performs switching control on the first switch 104 and the second switch 108 in accordance with the selection result of step SP26. For example, when the tip electrode 24 is selected as the transmitting electrode, the communication control unit 110 outputs a switch control signal SWC1 for connecting the tip electrode 24 to the E1 terminal of the first switch 104, and outputs a switch control signal SWC2 for connecting the tip electrode 24 to the T terminal of the second switch 108. When the tail electrode 32 is selected as the transmitting electrode, the communication control unit 110 outputs a switch control signal SWC1 for connecting the tail electrode 32 to the E2 terminal of the first switch 104, and outputs a switch control signal SWC2 for connecting the tail electrode 32 to the T terminal of the second switch 108.

[0107] In step SP30, the pen-side MCU 106 performs transmission control on the transmission electrodes selected in step SP28. Through this transmission control, a downlink signal DS is transmitted to the touch device 14. Thereafter, the pen controller 100 returns to step SP20 and sequentially executes steps SP20 to SP30.

[0108] In this way, the pen controller 100 performs communication with the touch device 14 (that is, communication in the AES format) by repeatedly executing steps SP20 to SP30 in FIG.

[0109] As in the first embodiment, the touch device 14 receives a downlink signal DS (more specifically, a first signal corresponding to the tip electrode 24 or a second signal corresponding to the tail electrode 32) from the active pen 12B on a frame-by-frame basis. Specifically, when receiving a downlink signal DS, the signal acquisition unit 88 in FIG. 5 performs reception control to demodulate the data using communication parameters. For example, when the frame definition table T1 is known, the signal acquisition unit 88 determines whether the signal is the first signal or the second signal based on the time slot within the frame. Alternatively, when the communication information table T2 is known, the signal acquisition unit 88 determines whether the signal is the first signal or the second signal based on the communication parameters.

[0110] Summary of Second Embodiment As described above, the active pen 12B in the second embodiment is used together with the touch device 14 configured to include a capacitive touch sensor 16 formed by arranging a plurality of sensor electrodes 16x, 16y in a planar manner. The active pen 12B includes a housing 22, a first electrode (here, the tip electrode 24) provided on the tip side of the housing 22, a second electrode (here, the tail electrode 32) provided on the tail side of the housing 22, an attitude sensor (here, the gyro sensor 102) that outputs a detection signal indicative of the attitude of the housing 22, and a pen controller 100 that switches the connection state between the tip electrode 24 and the tail electrode 32 in accordance with the detection signal from the gyro sensor 102 and transmits a downlink signal DS to the touch device 14.

[0111] This configuration makes it possible to transmit the downlink signal DS from the pen electrode according to the attitude of the housing 22, eliminating the need for a user operation to switch between the tip electrode 24 and the tail electrode 32. This improves usability for the user when switching between multiple types of functions of the active pen 12B.

[0112] Furthermore, the pen controller 100 may connect to the tip electrode 24 to transmit the downlink signal DS when the tip electrode 24 faces downward relative to the horizontal, and may connect to the tail electrode 32 to transmit the downlink signal DS when the tip electrode 24 faces upward relative to the horizontal. This allows the downlink signal DS to be transmitted via the pen electrode that is estimated to be closest to the touch device 14 when the touch device 14 is positioned approximately horizontally.

[0113] The pen controller 100 may also include an integrated circuit 103 that generates a downlink signal DS and outputs it from one terminal, and a first switch 104 that is connected to the one terminal and switches the output destination to either the tip electrode 24 or the tail electrode 32. This allows charging and discharging of parasitic capacitance to occur only at either the tip electrode 24 or the tail electrode 32 that is connected to the first switch 104, thereby reducing power consumption compared to when the integrated circuit 103 is always connected to both the tip electrode 24 and the tail electrode 32. In addition, the implementation of the first switch 104 has the additional effect of increasing the expandability of the transmission function via the tail electrode 32.

[0114] Furthermore, the pen controller 100 may transmit signals in frame units each including a first time slot indicating a time period for transmitting a first signal corresponding to the tip electrode 24 and a second time slot indicating a time period for transmitting a second signal corresponding to the tail electrode 32. This makes it possible to distinguish between the first signal and the second signal depending on the time slot.

[0115] 10 and 11 , the gyro sensor 102 is provided inside the housing 22. However, the attitude sensor is not limited to this configuration. For example, the attitude sensor may be an inertial measurement unit (IMU) capable of measuring three-axis acceleration and angular velocity.

[0116] 11 and 12, the tip side sensor 30 or the tail side sensor 34 (FIG. 10) may be connected to the pen side MCU 106, as in the first embodiment (FIG. 5). For example, the communication control unit 110 can prevent an erase operation against the user's intention that accompanies transmission of the eraser signal by controlling the tail electrode 32 to transmit a downlink signal DS only while contact on the tail side is detected by the tail side sensor 34.

[0117] In the second embodiment described above, the first electrode is the tip electrode 24 and the second electrode is the tail electrode 32, but the present invention is not limited to this combination. For example, the first electrode may be the ring electrode 26 and the second electrode may be the tail electrode 32.

[0118] The present invention is not limited to the above-described embodiments and modifications, and can be freely modified without departing from the spirit of the present invention. Alternatively, the respective configurations may be arbitrarily combined within the scope of no technical contradiction. Alternatively, the execution order of the steps constituting the flowchart may be changed within the scope of no technical contradiction.

[0119] [Explanation of symbols] 10, 10A, 10B: Position detection system, 12, 12A, 12B: Active pen, 14: Touch device, 16: Touch sensor, 16x, 16y: Sensor electrodes, 18: Sensor controller, 20: Host processor, 24: Tip electrode (first electrode), 26: Ring electrode, 30: Tip side sensor, 32: Tail electrode (second electrode), 34: Tail side sensor (contact sensor), 36, 100: Pen controller (integrated circuit), 102: Gyro sensor (attitude sensor), 103: Integrated circuit, 104: Second switch (output switch), DS: Downlink signal, US: Uplink signal

Claims

1. An active pen used with a touch device comprising a capacitive touch sensor having a plurality of sensor electrodes arranged in a surface, comprising: a first electrode; a second electrode provided at a position different from the first electrode; a transmitting circuit connected to the first electrode and the second electrode; and a pen control circuit that controls the transmitting circuit to transmit signals to the touch device in frame units via the first electrode or the second electrode, wherein the frame comprises a first time slot indicating a time period during which a first signal including first data is transmitted via the first electrode, and a second time slot indicating a time period during which a second signal including second data is transmitted via the second electrode.

2. The active pen according to claim 1, wherein the pen control circuit performs the transmission control to generate or modulate a carrier signal using first communication parameters when transmitting the first signal, and to generate or modulate a carrier signal using second communication parameters different from the first communication parameters when transmitting the second signal.

3. The active pen according to claim 1, wherein the pen control circuit changes the configuration of the first time slot or the second time slot within the frame depending on the reception status of a signal from an external device or the content of received data identified from the signal.

4. An active pen as described in claim 1, wherein the first electrode is provided on the tip side, the second electrode is provided on the tail side, and further comprising a contact sensor that detects contact with the tail side, and the pen control circuit stops transmitting the second signal while the contact is not detected by the contact sensor.

5. A touch device comprising: a capacitive touch sensor having a plurality of sensor electrodes arranged in a plane; and a sensor controller that receives signals from an active pen on a frame-by-frame basis via the sensor electrodes, wherein the frames include a first time slot indicating a time period during which a first signal is received, the first signal being generated or modulated by using a first communication parameter, and a second time slot indicating a time period during which a second signal is received, the second signal being generated or modulated by using a second communication parameter; and wherein the sensor controller acquires first data contained in the first signal or second data contained in the second signal through a demodulation process using the first communication parameter and the second communication parameter.

6. The touch device according to claim 5, wherein the active pen is configured to include a first electrode and a second electrode provided at a position different from the first electrode, and the sensor controller determines that the signal is from the first electrode when the first data can be acquired through a demodulation process using the first communication parameters, and determines that the signal is from the second electrode when the second data can be acquired through a demodulation process using the second communication parameters.

7. An active pen used with a touch device comprising a capacitive touch sensor having a plurality of sensor electrodes arranged in a surface, the active pen comprising: a housing; a first electrode provided on the tip side of the housing; a second electrode provided on the tail side of the housing; an attitude sensor that outputs a detection signal indicating the attitude of the housing; and a pen controller that switches the connection state between the first electrode and the second electrode in response to the detection signal from the attitude sensor and transmits a signal to the touch device.

8. The active pen according to claim 7, wherein the pen controller connects to the first electrode and transmits the signal when the first electrode faces downward relative to the horizontal, and connects to the second electrode and transmits the signal when the first electrode faces upward relative to the horizontal.

9. The active pen according to claim 7, wherein the pen controller comprises: an integrated circuit that generates the signal and outputs it from one terminal; and an output switch that is connected to the one terminal and switches the output destination to the first electrode or the second electrode.

10. The active pen described in claim 7, wherein the pen controller transmits signals in frame units each of which includes a first time slot indicating a time period for transmitting a first signal corresponding to the first electrode, and a second time slot indicating a time period for transmitting a second signal corresponding to the second electrode.

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