Method of palm rejection and sensor controller

Abstract

To exclude a contact position of a palm from an instruction position of an active pen, which will not rely on a result of detection by a process different from detection of the active pen, such as touch detection.SOLUTION: A method of palm rejection is executed by a sensor controller that is connected to a plurality of sensor electrodes and that detects a downlink signal transmitted from an active pen. The downlink signal includes a predetermined waveform portion shared in advance between the sensor controller and the active pen, and the predetermined waveform portion is a portion obtained by modulating a preamble shared in advance between the sensor controller and the active pen. The method includes: a determination step of determining whether or not a phase of the predetermined waveform portion included in the detected downlink signal is inverted; and an output step of outputting a position of the active pen derived on the basis of a distribution of levels of the downlink signal in the plurality of sensor electrodes when it is determined that the phase is not inverted.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to a palm rejection method and a sensor controller. [Background technology]

[0002] A position detector that realizes pen input using an active pen is known. The active pen is an electronic pen configured to transmit a downlink signal from a pen tip electrode provided at the pen tip. The position detector is configured to attempt to detect the downlink signal at each of multiple sensor electrodes arranged on the touch surface and detect the pointing position of the active pen based on the result.

[0003] The downlink signal is transmitted through the active pen housing to the body of the user holding the active pen. As a result, the downlink signal is transmitted not only from the pen tip electrode but also from the user's palm. Therefore, when the user places their hand on the touch surface, the downlink signal transmitted from the palm is also detected by the sensor electrode. Since the position detected based on the results of this detection cannot be said to accurately reflect the active pen's pointing position, it must be excluded from the active pen's pointing position. Hereinafter, excluding the palm's contact position from the active pen's pointing position is referred to as "palm rejection."

[0004] Patent Document 1 discloses an example of a technology for achieving palm rejection. This technology combines the detection result of a finger touch with the reception result of a downlink signal to determine whether the detected position of the downlink signal is the palm contact position or the pointing position of the active pen, and based on the result, the palm contact position is excluded from the pointing position of the active pen. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2018 / 225204 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the palm rejection described in Patent Document 1 requires the results of touch detection, and therefore cannot be performed in a mode where touch detection is stopped and only active pen detection is performed (pen-only mode).

[0007] Furthermore, in order to correctly determine the palm contact position in the palm rejection described in Patent Document 1, the area detected by palm contact in touch detection needs to be large enough to be distinguishable from the area detected by normal finger contact. Therefore, if the palm touch is only light and is detected only in an area that cannot be distinguished from normal finger contact, a correct determination cannot be made.

[0008] Therefore, one of the objects of the present invention is to provide a palm rejection method and a sensor controller that can exclude the palm contact position from the active pen's pointing position without relying on the results of detection by a process different from the active pen's detection, such as touch detection. [Means for solving the problem]

[0009] The palm rejection method according to the present invention is a palm rejection method executed by a sensor controller connected to a plurality of sensor electrodes and detecting a downlink signal transmitted from an active pen, the method including a determination step of determining whether the phase of the detected downlink signal matches a phase previously shared between the sensor controller and the active pen, and an output step of outputting the position of the active pen derived based on the distribution of levels of the downlink signal in the plurality of sensor electrodes when the determination step determines that they match.

[0010] The sensor controller according to the present invention is a sensor controller that is connected to a plurality of sensor electrodes and detects a downlink signal of a predetermined frequency or a predetermined waveform transmitted from an active pen, determines whether the phase of the detected downlink signal matches a phase shared in advance between the sensor controller and the active pen, and if it determines that the phase matches, outputs the position of the active pen derived based on the distribution of levels of the downlink signal in the plurality of sensor electrodes. [Effects of the Invention]

[0011] Assuming the human body is not sufficiently grounded, the downlink signal detected via the human body will have an inverted phase compared to the downlink signal detected via the pen tip electrode. According to the present invention, the phase of the downlink signal is determined, allowing a position derived based on the downlink signal detected via the human body to be identified. Therefore, it is possible to exclude the palm contact position from the active pen pointing position without relying on the results of detection by a process other than active pen detection, such as touch detection. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a diagram showing a configuration of an electronic device 1 according to an embodiment of the present invention. [Figure 2] FIG. 2 is a diagram showing details of the sensor electrode group / display 4. [Figure 3] FIG. 10 is a diagram showing the format of a downlink signal DS transmitted by the active pen PE. [Figure 4] FIG. 2 is a diagram illustrating a modulation process of a data signal. [Figure 5] 1 is a diagram showing an equivalent circuit of the active pen PE, palm PA, and sensor electrode group / display 4. FIG. [Figure 6](a) is a diagram showing the time change of the potential VT of the pen tip electrode 21 and the potential VB of the palm PA simulated using the equivalent circuit of Figure 5, and (b) is a diagram showing the time change of the potential V4y-1 of the linear conductor 4y-1 and the potential V4y-2 of the linear conductor 4y-2 simulated using the equivalent circuit of Figure 5. [Figure 7] (a) is a diagram showing the time change of the potential VT of the pen tip electrode 21 and the potential VB of the palm PA simulated using the equivalent circuit of Figure 5, and (b) is a diagram showing the time change of the potential V4y-1 of the linear conductor 4y-1 and the potential V4y-2 of the linear conductor 4y-2 simulated using the equivalent circuit of Figure 5. [Figure 8] 2 is a diagram showing a configuration of a sensor controller 2 according to an embodiment of the present invention. FIG. [Figure 9] 10 is a flowchart showing a pen detection process executed by the sensor controller 2. FIG. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0014] 1 is a diagram showing the configuration of an electronic device 1 according to this embodiment. The electronic device 1 is a device that supports pen input and finger touch input, such as a tablet computer, and is configured to include a sensor controller 2, a host processor 3, and a sensor electrode group / display 4, as shown in FIG.

[0015] 1 also shows an active pen PE that performs pen input to the electronic device 1. The active pen PE is a stylus that supports an active electrostatic method and is configured to be capable of bidirectional communication with the sensor controller 2 or capable of unidirectionally transmitting signals to the sensor controller 2. Hereinafter, a signal transmitted from the sensor controller 2 to the active pen PE will be referred to as an uplink signal US, and a signal transmitted from the active pen PE to the sensor controller 2 will be referred to as a downlink signal DS. A user performs pen input by operating the active pen PE on a panel surface 1a (touch surface) provided on the electronic device 1, and performs finger touch input by tracing the panel surface 1a with a finger.

[0016] The host processor 3 is a processor that controls the entire electronic device 1, and the operations of each unit in the electronic device 1, which will be described later, are executed under the control of the host processor 3. The sensor controller 2 is an integrated circuit that uses a group of sensor electrodes (described later) in the group of sensor electrodes / display 4 to derive the position of a pointer, such as the active pen PE or a user's finger, on the panel surface 1a and receives data transmitted by the active pen PE. The sensor controller 2 is configured to sequentially output the derived position and data received from the active pen PE to the host processor 3. The host processor 3 generates and draws digital ink based on the position and data thus input.

[0017] The sensor electrode group / display 4 is a device that integrates a sensor electrode group for realizing pen input and finger touch input with an electrode group that constitutes a display. Specific forms of the sensor electrode group / display 4 include an in-cell type, in which some or all of the electrodes that constitute the display are also used as some or all of the sensor electrodes, and an on-cell type, in which the electrodes that constitute the display and the sensor electrode group are electrically separated. In this embodiment, the sensor electrode group / display 4 will be described as an in-cell type. However, the present invention is also applicable to cases in which the sensor electrode group / display 4 is an on-cell type, or cases in which the sensor electrode group and the display are separate devices. Various displays, such as a liquid crystal display or an organic EL display, can be used as the display that constitutes the sensor electrode group / display 4. In this embodiment, the description will be continued assuming that the sensor electrode group / display 4 is a TFT (Thin Film Transistor) liquid crystal display.

[0018] Fig. 2 is a diagram showing the details of the sensor electrode group / display 4. As shown in the figure, the sensor electrode group / display 4 is composed of, in order from the side closest to the panel surface 1a, a plurality of island-shaped conductors 4m arranged in a matrix in the xy plane, a plurality of linear conductors 4y each extending in the x direction and juxtaposed in the y direction, and a plurality of linear conductors 4x each extending in the y direction and juxtaposed in the x direction. Note that the actual sensor electrode group / display 4 also includes various other components such as a liquid crystal layer, but these are not shown in Fig. 2.

[0019] The plurality of island-shaped conductors 4m, the plurality of linear conductors 4y, and the plurality of linear conductors 4x are each switchably connected to either the host processor 3 or the sensor controller 2. This switching is performed in a time-division manner by the host processor 3. The sensor electrode group / display 4 is used as a display when each conductor is connected to the host processor 3, and is used as a sensor electrode group when connected to the sensor controller 2.

[0020] When the sensor electrode group / display 4 is used as a display, the host processor 3 supplies a common potential Vcom to each of the multiple island-shaped conductors 4m, and uses the multiple linear conductors 4x as gate lines for controlling the on / off of pixel transistors (not shown), and uses the multiple linear conductors 4y as data / source lines for supplying data to the pixels.

[0021] On the other hand, when the sensor electrode group / display 4 is used as a sensor electrode group, the sensor controller 2 uses each of the multiple island conductors 4m as a sensor electrode to detect finger touches using a self-capacitance method, and uses each of the multiple linear conductors 4x, 4y as a sensor electrode to detect the active pen PE using an active electrostatic method.

[0022] 2 also shows the internal configuration of the active pen PE. As shown in the figure, the active pen PE includes a core body 20, a pen tip electrode 21, a pressure sensor 22, a switch 23, a control circuit 24, and a battery 25.

[0023] The core body 20 is a component that constitutes the pen tip of the active pen PE. The rear end of the core body 20 is connected to a pressure sensor 22. The pen tip electrode 21 is an electrode provided near the tip of the core body 20, and is electrically connected to a control circuit 24. The pressure sensor 22 is a sensor that detects the pressure applied to the tip of the core body 20. The switch 23 is a switch element provided on the surface of the housing of the active pen PE, and is configured to be able to be turned on and off by the user.

[0024] The control circuit 24 is a circuit that operates using power supplied from the battery 25 and performs various processes. In addition to controlling each part of the active pen PE, the processes performed by the control circuit 24 include a process of transmitting a downlink signal DS by controlling the potential of the pen tip electrode 21, and a process of receiving an uplink signal US by detecting and demodulating fluctuations in the potential of the pen tip electrode 21.

[0025] Figure 3 is a diagram showing the format of the downlink signal DS transmitted by the control circuit 24. Figure 3(a) shows the downlink signal DS transmitted by the control circuit 24 when the sensor controller 2 and the active pen PE are communicating bidirectionally and the control circuit 24 has not yet detected the sensor controller 2. In this case, the downlink signal DS is composed of a burst signal, which is an unmodulated carrier signal of a predetermined frequency.

[0026] 3(b) shows the downlink signal DS transmitted by the control circuit 24 in accordance with the received uplink signal US when the sensor controller 2 and the active pen PE communicate bidirectionally. A similar downlink signal DS is also used when the active pen PE transmits a signal unidirectionally to the sensor controller 2. This downlink signal DS includes a burst signal, which is an unmodulated carrier signal of a predetermined frequency, and a data signal obtained by modulating the carrier signal of the predetermined frequency with transmission data.

[0027] As shown in Fig. 3(b), the transmission data transmitted by the data signal includes a preamble indicating the start of the data signal and data requested by the uplink signal US. Note that error detection data such as a cyclic redundancy check (CRC) code may be placed at the end of the data signal.

[0028] The preamble is predetermined data shared in advance between the sensor controller 2 and the active pen PE, and is used by the sensor controller 2 to detect a data signal from the received signal. The data requested by the uplink signal US includes a pen pressure value indicating the pressure detected by the pressure sensor 22, switch information indicating the on / off status of the switch 23, a pen ID stored in memory in the control circuit 24, and the like. The control circuit 24 acquires data from the pressure sensor 22 and the like in accordance with the commands included in the received uplink signal US, and places the data in the data signal.

[0029] FIG. 4 is a diagram illustrating the modulation process of a data signal. As shown in the diagram, the control circuit 24 first acquires a symbol string that constitutes the transmission data. A symbol is a unit of information used for modulation, and includes values ​​that are converted into bit strings and values ​​that are not converted into bit strings. The illustrated "P" is an example of a symbol value that is not converted into a bit string. The value that is converted into a bit string is a value that corresponds to a bit string of a predetermined number of bits, and FIG. 4 shows an example that corresponds to a bit string of 4 bits.

[0030] The control circuit 24 stores in advance a table that associates symbol values ​​with spreading codes (chip sequences), and converts each symbol constituting the transmission data into a chip sequence according to this table. The control circuit 24 then Manchester-encodes the resulting chip sequence to prevent consecutive 0s or 1s, and then modulates the carrier signal with the Manchester-encoded chip sequence. While FIG. 4 shows an example in which this modulation is performed using BPSK (Binary Phase Shift Keying), other modulation methods may also be used. The waveform of the modulated carrier signal forms the waveform (transmission waveform) of the downlink signal DS transmitted from the pen tip electrode 21.

[0031] Returning to FIG. 2, we will now explain the outline of how the active pen PE is detected, taking as an example a case where the sensor controller 2 and the active pen PE communicate bidirectionally. The sensor controller 2, which has not yet detected the active pen PE, periodically transmits an uplink signal US using one or both of the multiple linear conductors 4x and 4y. Upon receiving this uplink signal US, the active pen PE first transmits a downlink signal DS of the type shown in FIG. 3(a). The sensor controller 2 sequentially scans all of the multiple linear conductors 4x and 4y to obtain the signal levels of the downlink signal DS for each of the linear conductors 4x and 4y. The position of the active pen PE is then derived based on this distribution and stored in memory (global scan).

[0032] After that, the active pen PE, which has received the uplink signal US again, transmits a downlink signal DS of the type shown in FIG. 3(b). The sensor controller 2, which receives this downlink signal DS, first receives burst signals using only a predetermined number of linear conductors 4x and 4y located near the position of the active pen PE stored in memory, and derives a new position of the active pen PE based on the distribution of signal levels. The position of the active pen PE stored in memory is then updated with the derived position (local scan). The sensor controller 2 then receives a data signal using the linear conductor 4x or 4y closest to the position of the active pen PE, thereby acquiring the data transmitted by the active pen PE. The positions and acquired data stored in memory in this way are sequentially output from the sensor controller 2 to the host processor 3, as described above.

[0033] To briefly explain the case where the active pen PE transmits a downlink signal DS unidirectionally to the sensor controller 2, the active pen PE is configured to periodically transmit a downlink signal DS of the type shown in FIG. 3(b). The sensor controller 2 performs the global scan described above based on this downlink signal DS when it has not yet detected the active pen PE. After temporarily storing the position of the active pen PE in memory through the global scan, the sensor controller 2 continues to perform the local scan and receive data signals based on the downlink signal DS transmitted from the active pen PE. This allows the sensor controller 2 to update the position of the active pen PE and acquire data transmitted by the active pen PE, just as in the case where the sensor controller 2 and the active pen PE communicate bidirectionally. The position stored in memory and the acquired data are sequentially output from the sensor controller 2 to the host processor 3, just as in the case where the sensor controller 2 and the active pen PE communicate bidirectionally.

[0034] Returning to FIG. 1, when the active pen PE transmits a downlink signal DS, the downlink signal DS is also transmitted to the body of the user holding the active pen PE through the housing of the active pen PE. As a result, if the user places his / her hand on the panel surface 1a, the downlink signal DS is also transmitted from the user's palm PA, as shown in FIG. 1. In this case, two peaks in the signal level are detected in the global scan, which may prevent the sensor controller 2 from correctly detecting the position of the active pen PE. Therefore, in this embodiment, the downlink signal DS includes a predetermined waveform portion (i.e., a transmission waveform corresponding to a preamble) shared in advance between the sensor controller 2 and the active pen PE. The sensor controller 2 is configured to determine whether the phase of the received downlink signal DS matches the phase shared in advance between the sensor controller 2 and the active pen PE based on the phase of this predetermined waveform portion. This makes it possible to exclude the contact position of the palm PA from the pointing position of the active pen PE.

[0035] Furthermore, to achieve this exclusion, it is necessary to determine the phase of the downlink signal DS before determining the pointing position of the active pen PE, and to do so, it is necessary to detect multiple positions by global scanning, and then perform local scanning and receive data signals at each of the multiple positions. Therefore, in this embodiment, the receiving section within the sensor controller 2 is configured to enable this type of processing.

[0036] In the following, we will first explain the relationship between the downlink signal DS and the phase with reference to Figures 5 to 7, then explain the configuration of the receiving unit provided in the sensor controller 2 with reference to Figure 8, and then explain in detail the processing performed by the sensor controller 2 with reference to Figure 9.

[0037] FIG. 5 is a diagram showing an equivalent circuit of the active pen PE, palm PA, and sensor electrode group / display 4. In this equivalent circuit, the human body is considered to be a perfect conductor and to be in a floating state. As shown in FIG. 5, this equivalent circuit includes four capacitances C1 to C4. The capacitance C1 is the coupling capacitance between the linear conductor 4y (hereinafter referred to as "linear conductor 4y-1") closest to the pen tip electrode 21 and the pen tip electrode 21. The capacitance C2 is the coupling capacitance between the linear conductor 4y (hereinafter referred to as "linear conductor 4y-2") closest to the palm PA and the palm PA. The capacitances C3 and C4 are the coupling capacitances between the linear conductors 4y-1 and 4y-2 and the ground terminal of the electronic device 1, respectively.

[0038] The potential of the pen tip electrode 21 relative to the ground terminal of the electronic device 1 is V T The potential of palm PA relative to the ground terminal of electronic device 1 is V B and the potential of the downlink signal DS is V S Then, they have the relationship shown in the following equation (1). V T -V B =V S ···(1)

[0039] In addition, the impedance between the ground terminal of the electronic device 1 and the pen tip electrode 21 is Z TG , the impedance between the ground end of electronic device 1 and palm PA is Z BG Then, according to Kirchhoff's first law, the following equation (2) holds. V T / Z TG +V B / Z BG =0 (2)

[0040] From equations (1) and (2), the following equations (3) and (4) are obtained. V T =-V S Z BG / (Z TG +Z BG ) ···(3) V B =V S ZBG / (Z TG +Z BG ) ···(4)

[0041] From equations (3) and (4), the potential V of the pen tip electrode 21 is T and the potential V of the palm B It can be understood that these have an opposite phase relationship. The sensor controller 2 according to this embodiment utilizes this relationship to perform processing to exclude the contact position of the palm PA from the pointing position of the active pen PE.

[0042] 6(a) and 7(a) show the potential V simulated using the equivalent circuit of FIG. T ,V B 6(b) and 7(b) are graphs showing the time change of the potential V of the linear conductor 4y-1 simulated using the equivalent circuit of FIG. 4y-1 and the potential V of the linear conductor 4y-2 4y-2 6(a) and 6(b) show the case where the coupling capacitance C1 is 1 pF, and FIGS. 7(a) and 7(b) show the case where the coupling capacitance C1 is 0.1 pF. In both figures, the coupling capacitances C2, C3, and C4 are set to 3 pF, 100 pF, and 100 pF, respectively.

[0043] As shown in FIG. 6(a) and FIG. 7(a), the potential V T and the potential V of the palm B These are the results shown in the above equations (3) and (4). On the other hand, from the results of Fig. 6(a) and Fig. 7(a), it can be seen that the potential V B The amplitude of the potential V T It is understood that the amplitude of the

[0044] In contrast, as shown in FIG. 6(b) and FIG. 7(b), the potential V 4y-1 and the potential V of the linear conductor 4y-2 4y-2 The potential V T and potential V B Same as above, but at potential VT ,V B The amplitude is the same as that of the sensor controller 2. T ,V B rather than the potential V 4y-1 ,V 4y-2 6(b) and 7(b), it can be understood that it is not possible to distinguish between the pointing position of the active pen PE and the contact position of the palm PA by only looking at the amplitude of the detected potential. 4y-1 ,V 4y-2 By referring to the phase of the active pen PE, the process is performed to exclude the contact position of the palm PA from the pointing position of the active pen PE.

[0045] 8 is a diagram showing the configuration of the sensor controller 2 according to this embodiment. However, this diagram shows only the portion related to reception of the downlink signal DS among the various components provided in the sensor controller 2. As shown in this diagram, the sensor controller 2 according to this embodiment is configured to include an MCU (Micro Control Unit) 10, a memory 11, n receiving units 12-1 to 12-n, and a selecting unit 13.

[0046] The MCU 10 is a processor that reads and executes programs stored in the memory 11. The processing performed by the MCU 10 includes control of each component within the sensor controller 2. The memory 11 is a storage device configured with volatile and / or nonvolatile memory, and stores programs executed by the MCU 10 while also functioning as a work memory for the MCU 10. This work memory function includes temporarily storing one or more positions derived by the MCU 10 as a result of global and local scans. The memory 11 also serves to store the same spread code (chip sequence) table stored in the control circuit 24 of the active pen PE.

[0047] Each of the receiving units 12-1 to 12-n includes a buffer 30, a band-pass filter 31, an analog-to-digital (AD) conversion unit 32, a demodulation unit 33, and a correlation calculation unit 34. The buffer 30 is connected to one of the plurality of linear conductors 4x, 4y via the selection unit 13, and serves to amplify the current induced in the connected linear conductor and supply the amplified current to the band-pass filter 31.

[0048] The bandpass filter 31 is a filter circuit that extracts only signals in a predetermined frequency band, to which the frequency of the downlink signal DS belongs, from the output current of the buffer 30. The bandpass filter 31 serves to remove low-frequency noise and harmonic noise from the output current of the buffer 30.

[0049] The AD conversion unit 32 is a circuit that acquires the reception level value of the downlink signal DS by sampling and quantizing the output signal of the bandpass filter 31. The sampling frequency of the AD conversion unit 32 is set to a frequency that is sufficiently higher than the frequency of the downlink signal DS. The AD conversion unit 32 is configured to sequentially supply the acquired reception level values ​​to the MCU 10 and the demodulation unit 33.

[0050] The demodulation unit 33 is a circuit that acquires a series of chip sequences transmitted by the active pen PE by demodulating the downlink signal DS based on a series of reception level values ​​output from the AD conversion unit 32. The series of chip sequences acquired by the demodulation unit 33 is supplied to a correlation calculation unit 34.

[0051] The correlation calculation unit 34 is a circuit that restores a string of symbols that make up the downlink signal DS by calculating the correlation between the series of chip sequences supplied from the demodulation unit 33 and each of a plurality of chip sequences pre-stored in the memory 11. The string of symbols restored by the correlation calculation unit 34 is supplied to the MCU 10.

[0052] The selector 13 is a multiplexer provided between each of the plurality of linear conductors 4x, 4y and the receivers 12-1 to 12-n. The connection state of the selector 13 is controlled by the MCU 10. Specifically, when performing a global scan, the MCU 10 controls the selector 13 so that each of the plurality of linear conductors 4x, 4y is sequentially connected to the receiver 12-1. The MCU 10 then obtains the distribution of the reception level of the downlink signal DS by referring to the reception level values ​​sequentially output from the AD converter 32 of the receiver 12-1, and derives the position of the peak of this distribution. If there are multiple peaks in the distribution, multiple positions are derived. The MCU 10 stores the one or more derived positions in the memory 11 as the detection results of the global scan.

[0053] When performing a local scan, the MCU 10 assigns a different receiver 12-k (where k is 1 to n) to each of one or more positions stored in the memory 11, controls the selector 13 so that each of the predetermined number of linear conductors 4x, 4y located near the corresponding position is sequentially connected to each of the assigned receivers 12-k, and acquires a distribution of the reception level of the downlink signal DS for each receiver 12-k by referring to the reception level values ​​sequentially output from the AD converter 32 of each receiver 12-k.The MCU 10 then derives the position of the peak of this distribution for each receiver 12-k and overwrites the corresponding position stored in the memory 11 with the derived position.

[0054] When receiving a data signal, the MCU 10 assigns a different receiver 12-k to each of one or more positions stored in the memory 11, and controls the selector 13 so that the linear conductor 4x (or linear conductor 4y) closest to the corresponding position is connected to each assigned receiver 12-k. The MCU 10 then first attempts to detect a preamble by referring to the symbol sequence sequentially output from the correlation calculator 34 of each receiver 12-k as a result of the assignment. In this case, the MCU 10 also attempts to detect, in addition to pre-stored preambles, a portion of the symbol sequence output when the phase of the downlink signal DS input to the receiver 12-k is inverted (hereinafter referred to as an "inverted preamble"). If the MCU 10 detects a preamble, it determines that the phase of the downlink signal DS matches the phase previously shared between the sensor controller 2 and the active pen PE. On the other hand, if the MCU 10 detects an inverted preamble, it determines that the phase of the downlink signal DS does not match (is inverted) the phase previously shared between the sensor controller 2 and the active pen PE.

[0055] The MCU 10 acquires the transmission data of the active pen PE based on the symbol string output from the receiver 12-k that received the downlink signal DS that it has determined to have a phase that matches the phase previously shared between the sensor controller 2 and the active pen PE, and outputs the data together with the position of the receiver 12-k stored in the memory 11 to the host processor 3. Since other positions are not output to the host processor 3, this realizes excluding the contact position of the palm PA from the indicated positions of the active pen PE.

[0056] 9 is a flow diagram showing the pen detection process executed by the sensor controller 2. As shown in the figure, the sensor controller 2 first enters a discovery mode for detecting the active pen PE (step S1), and then executes a global scan in which all of the plurality of linear conductors 4x, 4y are scanned in order (step S2). The sensor controller 2 determines whether or not a downlink signal DS has been detected as a result of executing this global scan (step S3), and if not, returns to step S2 and repeats the global scan.

[0057] On the other hand, if it is determined in step S3 that a position has been detected, the sensor controller 2 derives one or more positions based on the results of the global scan and stores them in the memory 11 shown in Fig. 8 (step S4). The details of this derivation are as described above. After completing step S4, the sensor controller 2 enters an operation mode in which it accepts pen input from the detected active pen PE (step S5).

[0058] The sensor controller 2 that has entered the operation mode performs the above-described local scan in parallel using the receiving units 12-1 to 12-n shown in FIG. 8 at each of one or more positions stored in the memory 11 (step S6). The sensor controller 2 then determines whether or not a downlink signal DS has been detected as a result of performing this local scan (step S7). If no downlink signal DS has been detected, the sensor controller 2 returns to the discovery mode and continues processing. On the other hand, if it determines that a downlink signal DS has been detected, the sensor controller 2 derives a position based on the results of the local scan and overwrites the position stored in the memory 11 (step S8). The details of this derivation are also as described above. Here, depending on the position, there is a possibility that a peak will not be detected in the distribution of the reception level of the downlink signal DS. In such a case, the sensor controller 2 performs processing to erase the corresponding position from the memory 11.

[0059] Next, the sensor controller 2 receives a data signal at each position stored in the memory 11 (step S9). Specifically, the symbol sequence output from each receiver 12-k shown in FIG. 8 is acquired. Then, the phase of each received data signal (symbol sequence) is determined (step S10, determination step). As described above, this determination is made by attempting to detect a preamble and an inverted preamble in the symbol sequence output from each receiver 12-k, and if a preamble is detected, determining that the phase of the downlink signal DS matches the phase previously shared between the sensor controller 2 and the active pen PE, whereas if an inverted preamble is detected, determining that the phase of the downlink signal DS does not match (is inverted) the phase previously shared between the sensor controller 2 and the active pen PE.

[0060] Next, the sensor controller 2 acquires the transmission data of the active pen PE based on the data signal determined in step S10 to have a phase that matches that of the downlink signal DS (step S11), and outputs this to the host processor 3 together with the position stored in memory 11 corresponding to the data signal (step S12, output step). Other positions stored in memory 11 are not output. As a result, only the position derived based on the downlink signal DS having a phase that matches the phase previously shared between the sensor controller 2 and the active pen PE, and the data acquired based on the downlink signal DS, are output to the host processor 3. The sensor controller 2 then returns to step S6 to continue processing.

[0061] As described above, according to the palm rejection method executed by the sensor controller 2 of this embodiment, the phase of the downlink signal DS is determined in step S10, so it is possible to identify a position derived based on the downlink signal DS detected via the human body. Therefore, it is possible to exclude the contact position of the palm PA from the pointing position of the active pen PE without relying on the results of detection by a process different from the detection of the active pen PE, such as touch detection.

[0062] 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.

[0063] For example, in the above embodiment, an example has been described in which the MCU 10 performs processing to attempt to detect a preamble and an inverted preamble in the symbol sequence output from each receiving unit 12-k. However, this processing may be omitted when the sensor controller 2 and the active pen PE communicate bidirectionally. That is, when the sensor controller 2 and the active pen PE communicate bidirectionally, the sensor controller 2 that has entered the operation mode is synchronized with the active pen PE. Therefore, since the timing at which the downlink signal DS contains a preamble can be known in advance, the phase of the downlink signal DS can be determined by determining whether a preamble or an inverted preamble is output from each receiving unit 12-k at that timing.

[0064] Furthermore, in the above embodiment, an example has been described in which the phase of the downlink signal DS is determined based on the phase of the preamble, but any data other than the preamble can be used to determine the phase of the downlink signal DS as long as it is predetermined data shared in advance between the sensor controller 2 and the active pen PE. For example, if the data signal includes a start bit and a stop bit, the phase of the downlink signal DS may be determined based on the phase of either or both of these bits.

[0065] Furthermore, if the data signal contains data for error detection, it may be determined that the phase of the downlink signal DS is inverted when consecutive errors are detected. Alternatively, when an error is detected, the chip sequence output from the demodulator 33 may be inverted and re-input into the correlation calculator 34 to acquire a new symbol sequence, and if the acquired symbol sequence contains a preamble, it may be determined that the phase of the downlink signal DS is inverted.

[0066] Furthermore, in the above embodiment, an example has been described in which a plurality of receiving units 12-1 to 12-n are provided in the sensor controller 2, but only one receiving unit may be provided. In this case, it becomes impossible to determine the phase of the downlink signal DS in parallel at a plurality of positions, but it becomes possible to at least determine whether the received downlink signal DS has been transmitted from the pen tip electrode 21 or the palm PA. [Explanation of symbols]

[0067] 1 Electronic equipment 1a Panel surface 2 Sensor Controller 3 Host Processor 4 Sensor electrode group and display 4m island conductor 4x, 4y linear conductor 10 MCU 11. Memory 12 Receiving unit 13 Selection section 20 core body 21 Pen tip electrode 22 Pressure Sensor 23 Switch 24 Control circuit 25 Battery 30 buffers 31 Bandpass Filter 32 Analog-to-digital (AD) conversion section 33 Demodulation section 34 Correlation calculation unit DS downlink signal PA Palm PE Active Pen US uplink signal

Claims

1. 1. A method of palm rejection performed by a sensor controller connected to a plurality of sensor electrodes and detecting a downlink signal transmitted from an active pen, comprising: the downlink signal includes a portion of a predetermined waveform pre-shared between the sensor controller and the active pen; the predetermined waveform portion is a portion obtained by modulating a preamble shared in advance between the sensor controller and the active pen; a determining step of determining whether or not the phase of the predetermined waveform portion included in the detected downlink signal is inverted; an output step of outputting the position of the active pen derived based on the distribution of levels of the downlink signal at the plurality of sensor electrodes when it is determined that the downlink signal is not inverted by the determining step; A method comprising:

2. the output step does not output the position of the active pen derived based on the distribution of levels of the downlink signal at the plurality of sensor electrodes when it is determined that the inversion has occurred in the determination step; The method of claim 1.

3. The determination step determines that the phase of the predetermined waveform portion included in the detected downlink signal is not inverted if the preamble is included in the symbol string obtained by demodulating the downlink signal, and determines that the phase of the predetermined waveform portion included in the detected downlink signal is inverted if the symbol string includes an inverted preamble, which is a portion corresponding to the preamble in the symbol string obtained by demodulating the downlink signal when the phase of the predetermined waveform portion included in the downlink signal is inverted.

3. The method according to claim 1 or 2.

4. the sensor controller and the active pen are configured to be able to communicate bidirectionally in a synchronized state with each other; the determining step performs a process of determining whether or not the preamble or the inverted preamble is included in a symbol sequence obtained by demodulating the downlink signal at a timing when the preamble is included in the downlink signal. The method of claim 3.

5. the sensor controller includes a plurality of receivers; each of the plurality of receivers is configured to receive the downlink signal; the determining step determines whether or not a phase of the predetermined waveform portion included in the downlink signal detected by each of the plurality of receiving units is inverted; the output step outputs the position of the active pen derived based on the level distribution at the plurality of sensor electrodes of the downlink signal for which it has been determined in the determination step that the phase of the portion of the predetermined waveform has not been inverted, while not outputting the position of the active pen derived based on the level distribution at the plurality of sensor electrodes of the downlink signal for which it has been determined in the determination step that the phase of the portion of the predetermined waveform has been inverted.

5. The method according to any one of claims 1 to 4.

6. The sensor controller deriving a plurality of positions based on reception level values ​​of the downlink signal at each of the plurality of sensor electrodes; assigning different receiving units to the derived positions, respectively; connecting one of the sensor electrodes closest to a corresponding position to each of the assigned receiving units; the determining step determines whether or not a phase of the predetermined waveform portion included in the downlink signal detected by the receiving unit connected to any one of the sensor electrodes is inverted. The method of claim 5.

7. a sensor controller connected to a plurality of sensor electrodes and detecting a downlink signal of a predetermined frequency or a predetermined waveform transmitted from an active pen; the downlink signal includes a portion of a predetermined waveform pre-shared between the sensor controller and the active pen; the predetermined waveform portion is a portion obtained by modulating a preamble shared in advance between the sensor controller and the active pen; determining whether or not the phase of the predetermined waveform portion included in the detected downlink signal is inverted; When it is determined that the downlink signal is not inverted, the position of the active pen derived based on the distribution of levels of the downlink signal in the plurality of sensor electrodes is output. Sensor controller.

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