Palm rejection method and sensor controller

Abstract

To exclude a contact position of a palm from an indicated position of an active pen without depending on a result of detection by a process different from detection of the active pen such as touch detection.SOLUTION: Provided is a method of palm rejection executed by a sensor controller that is connected to a plurality of sensor electrodes and detects a downlink signal transmitted from an active pen, the method including: a step S10 of determining whether or not a phase of the downlink signal detected on the basis of a preamble included in the downlink signal matches a phase shared in advance between the sensor controller and the active pen; and a step S12 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 phases each other in the step S10.SELECTED DRAWING: Figure 9

Description

Technical Field

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

Background Art

[0002] A position detector for realizing pen input by 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 attempts to detect the downlink signal at each of a plurality of sensor electrodes arranged in the touch surface, and is configured to detect the indicated position of the active pen based on the result.

[0003] Incidentally, the downlink signal is transmitted not only through the housing of the active pen but also to the human body of the user holding the active pen. Then, the downlink signal is transmitted not only from the pen tip electrode but also from the palm of the user, so that when the user touches the touch surface with a hand, the downlink signal transmitted from the palm is also detected by the sensor electrode. Since the position detected based on the result of this detection cannot be said to correctly reflect the indicated position of the active pen, it is necessary to exclude it from the indicated position of the active pen. Hereinafter, excluding the contact position of the palm from the indicated position of the active pen is referred to as "palm rejection".

[0004] Patent Document 1 discloses an example of a technique for realizing palm rejection. In this technique, by combining the detection result of touch by a finger with the reception result of the downlink signal, it is determined whether the detected position of the downlink signal is the contact position of the palm or the indicated position of the active pen, and based on the result, the contact position of the palm is excluded from the indicated position of the active pen.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0006] However, in the palm rejection described in Patent Document 1, the result of touch detection is required. Therefore, it cannot be executed in a mode (pen-only mode) that stops touch detection and performs only active pen detection.

[0007] Further, in order to correctly determine the contact position of the palm in the palm rejection described in Patent Document 1, the area of the region detected by the contact of the palm in touch detection needs to be wide enough to be distinguishable from the region detected by the contact of a normal finger. Therefore, when the touch by the palm remains light and is detected only in a region that cannot be distinguished from the contact by a normal finger, the determination cannot be made correctly.

[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 contact position of the palm from the indicated position of the active pen without depending on the result of detection by a process different from the detection of the active pen such as touch detection.

MEANS FOR SOLVING THE PROBLEMS

[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 or not the phase of the detected downlink signal matches a phase pre-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 level distribution of the detected downlink signal at the plurality of sensor electrodes when it is determined in the determination step 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 waveform transmitted from an active pen, determines whether or not the phase of the detected downlink signal matches a phase shared in advance between the sensor controller and the active pen, and if it is determined that they match, outputs the position of the active pen derived based on the distribution of levels of the downlink signal in the plurality of sensor electrodes. Effect of the Invention

[0011] Assuming that 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, since the phase of the downlink signal is determined, it is possible to identify a position derived based on the downlink signal detected via the human body. Therefore, it is possible to exclude the palm contact position from the pointing position of the active pen without relying on the result of detection by a process different from the detection of the active pen, such as touch detection. [Brief description of the drawings]

[0012]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

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

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

[0015] Figure 1 also shows an active pen PE for performing pen input to the electronic device 1. The active pen PE is a stylus corresponding to the active electrostatic method, and is configured to be capable of two-way communication with the sensor controller 2 or to be able to transmit a signal unidirectionally to the sensor controller 2. Hereinafter, the signal transmitted from the sensor controller 2 to the active pen PE is referred to as an uplink signal US, and the signal transmitted from the active pen PE to the sensor controller 2 is referred to as a downlink signal DS. The user performs pen input by operating the active pen PE on the 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 part within the electronic device 1 described later are executed under the control of the host processor 3. The sensor controller 2 is an integrated circuit that uses a sensor electrode group (described later) within the sensor electrode group and display 4 to derive the position of an indicator such as the active pen PE or the user's finger within the panel surface 1a and to receive the data transmitted by the active pen PE. The sensor controller 2 is configured to sequentially output the derived position and the 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-cum-display 4 is a device in which a sensor electrode group for realizing pen input and finger touch input and an electrode group constituting the display are integrated. As specific forms of the sensor electrode group-cum-display 4, there are an in-cell type in which part or all of the electrode group constituting the display is also used as part or all of the sensor electrode group, an on-cell type in which the electrode group constituting the display and the sensor electrode group are electrically separated, etc. In the present embodiment, the description will continue assuming that the sensor electrode group-cum-display 4 is of the in-cell type. However, the present invention is also applicable when the sensor electrode group-cum-display 4 is of the on-cell type or when the sensor electrode group and the display are separate devices. As the display constituting the sensor electrode group-cum-display 4, various displays such as a liquid crystal display or an organic EL display can be used, but in the present embodiment, the description will continue assuming that it is a TFT (Thin Film Transistor) type liquid crystal display.

[0018] FIG. 2 is a diagram showing details of the sensor electrode group-cum-display 4. As shown in the figure, the sensor electrode group-cum-display 4 includes, in order from the side closer 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-cum-display 4 includes various members such as a liquid crystal layer in addition to these, but the description is omitted 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 executed by the host processor 3 in a time-division manner. The sensor electrode group-cum-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-shaped conductors 4m as a sensor electrode to detect finger touch 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] The internal configuration of the active pen PE is also shown in Fig. 2. 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 member 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 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. The processes performed by the control circuit 24 include, in addition to controlling each part of the active pen PE, 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] FIG. 3 is a diagram showing the format of the downlink signal DS transmitted by the control circuit 24. FIG. 3(a) shows the downlink signal DS transmitted by the control circuit 24 that has not yet detected the sensor controller 2 when the sensor controller 2 and the active pen PE communicate bidirectionally. The downlink signal DS in this case is composed of a burst signal that is an unmodulated carrier signal of a predetermined frequency.

[0026] FIG. 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. The same downlink signal DS is also used when the active pen PE transmits a signal in one direction to the sensor controller 2. This downlink signal DS is composed of a burst signal that is an unmodulated carrier signal of a predetermined frequency and a data signal obtained by modulating a carrier signal of a predetermined frequency with transmission data.

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

[0028] The preamble is predetermined data pre-shared between the sensor controller 2 and the active pen PE and is used for the sensor controller 2 to detect the 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 state of the switch 23, a pen ID stored in the 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 arranges it in the data signal.

[0029] FIG. 4 is a diagram for explaining the modulation process of data signals. As shown in the figure, the control circuit 24 first acquires a symbol sequence constituting the transmission data. A symbol is a unit of information used for modulation and includes a value that is converted into a bit sequence and a value that is not converted into a bit sequence. The illustrated "P" is an example of the value of a symbol that is not converted into a bit sequence. The value that is converted into a bit sequence is a value corresponding to a bit sequence of a predetermined number of bits, and FIG. 4 shows an example corresponding to a 4-bit bit sequence.

[0030] The control circuit 24 prestores a table associating the symbol values with spreading codes (chip sequences), and converts each symbol constituting the transmission data into a chip sequence according to this table. Subsequently, the control circuit 24 Manchester-encodes the obtained chip sequence so that 0 or 1 does not continue, and then modulates the carrier signal with the chip sequence after Manchester encoding. FIG. 4 shows an example in which this modulation is performed by BPSK (Binary Phase Shift Keying), but other modulation methods may also be used. The waveform of the downlink signal DS (transmission waveform) transmitted from the pen tip electrode 21 is configured by the waveform of the carrier signal modulated in this way.

[0031] Returning to FIG. 2, the outline of the detection of the active pen PE will be described by taking as an example the case where the sensor controller 2 and the active pen PE communicate bidirectionally. The sensor controller 2 that has not yet detected the active pen PE periodically transmits an uplink signal US using one or both of the plurality of linear conductors 4x and the plurality of linear conductors 4y. The active pen PE that has received this uplink signal US first transmits a downlink signal DS of the type shown in FIG. 3(a). The sensor controller 2 sequentially scans all of the plurality of linear conductors 4x and the plurality of linear conductors 4y to acquire the signal levels of this downlink signal DS in each of the linear conductors 4x and 4y. Then, based on the distribution, the position of the active pen PE is derived and stored in the memory (global scan).

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

[0033] The case where the downlink signal DS is transmitted unidirectionally from the active pen PE to the sensor controller 2 will be briefly described. The active pen PE is configured to periodically transmit a downlink signal DS of the type shown in Fig. 3(b). When the sensor controller 2 has not yet detected the active pen PE, it performs the above-described global scan based on this downlink signal DS. Once the position of the active pen PE is stored in the memory by the global scan, the sensor controller 2 continues to perform the above-described local scan and reception of the data signal based on the downlink signal DS transmitted from the active pen PE. As a result, the sensor controller 2 can update the position of the active pen PE and acquire the 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 fact that the position stored in the memory and the acquired data are sequentially output from the sensor controller 2 to the host processor 3 is also the same as in the case where the sensor controller 2 and the active pen PE communicate bidirectionally.

[0034] Return to FIG. 1. When the active pen PE transmits the downlink signal DS, the downlink signal DS also passes through the housing of the active pen PE and reaches the human body of the user holding the active pen PE. As a result, when the user's hand is on the panel surface 1a, as shown in FIG. 1, the downlink signal DS is also transmitted from the user's palm PA. Then, since there will be two peaks in the signal level detected in the global scan, there is a possibility that the sensor controller 2 cannot correctly detect the position of the active pen PE. Therefore, in the present embodiment, by utilizing the fact that the downlink signal DS includes a portion of a predetermined waveform (i.e., the transmission waveform corresponding to the preamble) that is pre-shared 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 pre-shared between the sensor controller 2 and the active pen PE based on the phase of this predetermined waveform portion, so that the contact position of the palm PA can be excluded from the indicated position of the active pen PE.

[0035] Also, in order to achieve this exclusion, it is necessary to determine the phase of the downlink signal DS before determining the indicated position of the active pen PE. For this purpose, it is necessary to detect a plurality of positions in the global scan and perform local scans and receive data signals at each of the plurality of positions. Therefore, in the present embodiment, the receiving section in the sensor controller 2 is configured to enable such processing.

[0036] First, the relationship between the downlink signal DS and the phase will be described with reference to FIGS. 5 to 7. Next, the configuration of the receiving section provided in the sensor controller 2 will be described with reference to FIG. 8. Then, the processing performed by the sensor controller 2 will be described in detail with reference to FIG. 9.

[0037] FIG. 5 is a diagram showing an equivalent circuit of the active pen PE, the palm PA, and the sensor electrode group and display 4. In this equivalent circuit, the human body is regarded as a perfect conductor and in a floating state. As shown in FIG. 5, this equivalent circuit is composed of four capacitances C1 to C4. 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. 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. 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] Let the potential of the pen tip electrode 21 with respect to the ground terminal of the electronic device 1 be V T and the potential of the palm PA with respect to the ground terminal of the electronic device 1 be V B and the potential of the downlink signal DS be V S Then, they have the relationship shown in the following formula (1). V T -V B =V S ···(1)

[0039] Also, let the impedance between the ground terminal of the electronic device 1 and the pen tip electrode 21 be Z TG and the impedance between the ground terminal of the electronic device 1 and the palm PA be Z BG Then, from Kirchhoff's first law, the following formula (2) holds. V T / Z TG +V B / Z BG =0 ···(2)

[0040] From formula (1) and formula (2), the following formula (3) and formula (4) can be 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), it is understood that the potential V of the pen tip electrode 21 T and the potential V of the palm PA B are in a reverse-phase relationship with each other. The sensor controller 2 according to the present embodiment uses this relationship to perform a process of excluding the contact position of the palm PA from the indicated position of the active pen PE.

[0042] Figures 6(a) and 7(a) are diagrams showing the time variations of the potentials V T , V B . Also, Figures 6(b) and 7(b) are diagrams showing the time variations of the potential V of the linear conductor 4y-1 4y-1 and the potential V of the linear conductor 4y-2 4y-2 simulated using the equivalent circuit of Figure 5. However, Figures 6(a)(b) show the case where the coupling capacitance C1 is 1 pF, and Figures 7(a)(b) show the case where the coupling capacitance C1 is 0.1 pF. In any of the figures, the coupling capacitances C2, C3, C4 are assumed to be 3 pF, 100 pF, 100 pF, respectively.

[0043] As shown in Figures 6(a) and 7(a), the potential V of the pen tip electrode 21 T and the potential V of the palm PA B are in a reverse-phase relationship with each other. This is the result as shown in the above-described equations (3) and (4). On the other hand, from the results of Figures 6(a) and 7(a), it is understood that the amplitude of the potential V B is smaller than the amplitude of the potential V T .

[0044] On the contrary, as shown in Figures 6(b) and 7(b), the potential V of the linear conductor 4y-1 4y-1 and the potential V of the linear conductor 4y-2 4y-2 are similar to the potentials V T and the potential V B in that they are in a reverse-phase relationship with each other, but the potential VT , V B , unlike this, the amplitudes are the same value. What the sensor controller 2 actually detects is the potential V T , V B , not the potential V 4y-1 , V 4y-2 , because of this, from the results of FIGS. 6(b) and 7(b), it is understood that it is impossible to distinguish the indicated position of the active pen PE and the contact position of the palm PA only by looking at the amplitude of the detected potential. Therefore, in the sensor controller 2 according to the present embodiment, by referring to the phase of the potential V 4y-1 , V 4y-2 , a process of excluding the contact position of the palm PA from the indicated position of the active pen PE is performed.

[0045] FIG. 8 is a diagram showing the configuration of the sensor controller 2 according to the present embodiment. However, in the figure, only the part related to the reception of the downlink signal DS among various configurations provided in the sensor controller 2 is shown. As shown in the figure, the sensor controller 2 according to the present embodiment includes an MCU (Micro Control Unit) 10, a memory 11, n reception units 12-1 to 12-n, and a selection unit 13.

[0046] The MCU 10 is a processor that reads and executes a program stored in the memory 11. The processing executed by the MCU 10 includes control of each part in the sensor controller 2. The memory 11 is a storage device composed of a volatile memory or a non-volatile memory and both of them, stores a program executed by the MCU 10, and functions as a work memory of the MCU 10. The function as this work memory includes a function of temporarily storing one or more positions derived as the results of the global scan and the local scan by the MCU 10. Further, the memory 11 serves to store the same thing as the table of the spreading code (chip sequence) 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 any one of the plurality of linear conductors 4x, 4y via the selection unit 13, amplifies the current induced in the connected linear conductor, and serves to supply it to the band-pass filter 31.

[0048] The band-pass filter 31 is a filter circuit that extracts only the signal in a predetermined frequency band to which the frequency of the downlink signal DS belongs from the output current of the buffer 30. The band-pass 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 obtains the reception level value of the downlink signal DS by performing sampling and quantization on the output signal of the band-pass filter 31. Note that the sampling frequency of the AD conversion unit 32 is set to a frequency sufficiently higher than the frequency of the downlink signal DS. The AD conversion unit 32 is configured to sequentially supply the obtained reception level value to the MCU 10 and the demodulation unit 33.

[0050] The demodulation unit 33 is a circuit that obtains 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 obtained by the demodulation unit 33 is supplied to the correlation calculation unit 34.

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

[0052] The selection unit 13 is a multiplexer provided between each of the plurality of linear conductors 4x, 4y and the receiving units 12-1 to 12-n. The connection state of the selection unit 13 is controlled by the MCU 10. Specifically, when the MCU 10 performs a global scan, it controls the selection unit 13 so that each of the plurality of linear conductors 4x, 4y is sequentially connected to the receiving unit 12-1. Then, the MCU 10 refers to the received level values sequentially output from the AD conversion unit 32 of the receiving unit 12-1 to obtain the distribution of the received level of the downlink signal DS, and derives the position of the peak of this distribution. If there are a plurality of peaks in the distribution, the number of derived positions will also be plural. The MCU 10 stores the one or more derived positions in the memory 11 as the detection result of the global scan.

[0053] When performing a local scan, the MCU 10 assigns different receiving units 12-k (k is any one of 1 to n) to each of the one or more positions stored in the memory 11. For each of the assigned receiving units 12-k, it controls the selection unit 13 so that each of the predetermined number of linear conductors 4x, 4y located in the vicinity of the corresponding position is sequentially connected. As a result, by referring to the received level values sequentially output from the AD conversion unit 32 of the receiving unit 12-k, for each receiving unit 12-k, the distribution of the received level of the downlink signal DS is obtained. Then, the MCU 10 derives the position of the peak of this distribution for each receiving unit 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 different receiving units 12-k to each of one or more positions stored in the memory 11, and controls the selection unit 13 so that the linear conductor 4x (or linear conductor 4y) closest to the corresponding position is connected to each of the assigned receiving units 12-k. Then, referring to the symbol sequences sequentially output from the correlation operation units 34 of the respective receiving units 12-k as a result, an attempt is first made to detect a preamble. At this time, in addition to the preamble stored in advance, the MCU 10 also attempts to detect the portion corresponding to the preamble in the symbol sequence output when the phase of the downlink signal DS input to the receiving unit 12-k is inverted (hereinafter referred to as the "inverted preamble"). When a preamble is detected, it is determined that the phase of the downlink signal DS matches the phase pre-shared between the sensor controller 2 and the active pen PE. On the other hand, when an inverted preamble is detected, it is determined that the phase of the downlink signal DS does not match (is inverted) the phase pre-shared between the sensor controller 2 and the active pen PE.

[0055] Based on the symbol sequence output from the receiving unit 12-k that has received the downlink signal DS determined to have a phase matching the phase pre-shared between the sensor controller 2 and the active pen PE as a result of the determination, the MCU 10 acquires the transmission data of the active pen PE, and outputs it to the host processor 3 together with the position stored in the memory 11 regarding the receiving unit 12-k. Since the other positions are not output to the host processor 3, this realizes excluding the contact position of the palm PA from the indicated position of the active pen PE.

[0056] FIG. 9 is a flowchart showing the pen detection process executed by the sensor controller 2. As shown in the figure, the sensor controller 2 first enters the discovery mode for detecting the active pen PE (step S1), and executes a global scan to sequentially scan all of the plurality of linear conductors 4x, 4y (step S2). The sensor controller 2 determines whether the downlink signal DS is detected as a result of executing this global scan (step S3). If not detected, it returns to step S2 to repeat the global scan.

[0057] On the other hand, if it is determined in step S3 that the downlink signal DS is detected, the sensor controller 2 derives one or more positions based on the result 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 the operation mode for receiving pen input by 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 at each of the one or more positions stored in the memory 11 using the receivers 12-1 to 12-n shown in FIG. 8 (step S6). Then, the sensor controller 2 determines whether the downlink signal DS is detected as a result of executing this local scan (step S7). If not detected, it returns to the discovery mode to continue the process. On the other hand, if it is determined that the downlink signal DS is detected, the position is derived based on the result of the local scan and the position stored in the memory 11 is overwritten (step S8). The details of this derivation are also as described above. Here, depending on the position, there may be a case where no peak is detected in the distribution of the reception level of the downlink signal DS. In such a case, the sensor controller 2 performs a process of deleting the corresponding position from the memory 11.

[0059] Next, the sensor controller 2 receives data signals at each position stored in the memory 11 (step S9). Specifically, it acquires the symbol sequences output from each receiving unit 12-k shown in FIG. 8. Then, for each of the received data signals (symbol sequences), it determines the phase (step S10, determination step). As described above, this determination attempts to detect the preamble and the inverted preamble in the symbol sequence output from each receiving unit 12-k. When the preamble is detected, it is determined that the phase of the downlink signal DS matches the phase pre-shared between the sensor controller 2 and the active pen PE. On the other hand, when the inverted preamble is detected, it is determined that the phase of the downlink signal DS does not match (is inverted) the phase pre-shared between the sensor controller 2 and the active pen PE.

[0060] Subsequently, the sensor controller 2 acquires the transmission data of the active pen PE based on the data signals determined in step S10 to have a matching phase of the downlink signal DS (step S11), and outputs it to the host processor 3 together with the position stored in the memory 11 corresponding to the data signal (step S12, output step). It does not output the other positions stored in the memory 11. As a result, only the position derived based on the downlink signal DS having a phase that matches the phase pre-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 the processing.

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

[0062] As described above, the preferred embodiments of the present invention have been described. However, the present invention is not limited to such embodiments, and it goes without saying that the present invention can be implemented in various modes without departing from the gist thereof.

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

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

[0065] Also, when the data signal includes error detection data, in the case where errors are continuously detected, it may be determined that the phase of the downlink signal DS is inverted. Alternatively, when an error is detected, the chip sequence output from the demodulation unit 33 is inverted and then re-input to the correlation operation unit 34 to obtain a symbol sequence again. When the obtained symbol sequence includes a preamble, it may be determined that the phase of the downlink signal DS is inverted.

[0066] In the above embodiment, an example of providing a plurality of receiving units 12-1 to 12-n in the sensor controller 2 has been described. However, 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. However, at least it is possible to determine whether the received downlink signal DS is transmitted from either the pen tip electrode 21 or the palm PA.

Explanation of Reference Numerals

[0067] 1 Electronic device 1a Panel surface 2 Sensor controller 3 Host processor 4 Sensor electrode group and display 4m Island-shaped conductor 4x, 4y Linear conductor 10 MCU 11 Memory 12 Receiving unit 13 Selection unit 20 Core 21 Pen Tip Electrode 22 Pressure Sensor 23 Switch 24 Control Circuit 25 Battery 30 Buffer 31 Band - Pass Filter 32 Analog - to - Digital (AD) Converter 33 Demodulation Unit 34 Correlation Calculation Unit DS Downlink Signal PA Palm PE Active Pen US Uplink Signal

Claims

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

2. The output step does not output the position of the active pen derived based on the level distribution of the plurality of sensor electrodes of the downlink signal when it is determined by the determination step that the phase is inverted. The method according to claim 1.

3. The portion of the predetermined waveform is a portion obtained by modulating predetermined data pre-shared between the sensor controller and the active pen. The method according to claim 1 or 2.

4. The predetermined data is any one of a preamble, a start bit, and a stop bit. The method according to claim 3.

5. In the determination step, when the predetermined data is included in the symbol sequence obtained by demodulating the downlink signal, it is determined that the phase of the portion of the predetermined waveform included in the detected downlink signal is not inverted, and when the symbol sequence includes inverted data which is a portion corresponding to the predetermined data in the symbol sequence obtained by demodulating the downlink signal when the phase of the portion of the predetermined waveform included in the downlink signal is inverted, it is determined that the phase of the portion of the predetermined waveform included in the detected downlink signal is inverted. The method according to claim 3 or 4.

6. The sensor controller and the active pen are configured to be capable of bidirectional communication in a synchronized state with each other. The determination step performs a process of determining whether the predetermined data or the inverted data is included in a symbol sequence obtained by demodulating the downlink signal at a timing when the predetermined data is included in the downlink signal. The method according to claim 5.

7. The sensor controller includes a plurality of receiving units. Each of the plurality of receiving units is configured to receive the downlink signal. The determination step determines whether the phase of the portion of the predetermined waveform included in the downlink signal detected in each of the plurality of receiving units is inverted. The output step outputs the position of the active pen derived based on the distribution of levels at the plurality of sensor electrodes of the downlink signal determined by the determination step not to have the phase of the portion of the predetermined waveform inverted, while not outputting the position of the active pen derived based on the distribution of levels at the plurality of sensor electrodes of the downlink signal determined by the determination step to have the phase of the portion of the predetermined waveform inverted. The method according to any one of claims 1 to 6.

8. The sensor controller derives a plurality of positions based on the reception level values of the downlink signal at each of the plurality of sensor electrodes, assigns different ones of the receiving units to each of the derived plurality of positions, connects one sensor electrode closest to the corresponding position to each of the assigned receiving units, and the determination step determines whether the phase of the portion of the predetermined waveform included in the downlink signal detected in the receiving unit connected to any of the sensor electrodes is inverted. The method according to claim 7.

9. 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, wherein the downlink signal includes a portion of a predetermined waveform pre-shared between the sensor controller and the active pen, and determines whether the phase of the portion of the predetermined waveform included in the downlink signal detected based on a preamble included in the downlink signal is inverted. When it is determined that the pen is not inverted, output the position of the active pen derived based on the distribution of levels in the plurality of sensor electrodes of the downlink signal. Sensor controller.

Images