US-12625577-B2 - Method of palm rejection and sensor controller

Abstract

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 method includes determining whether or not a phase of the detected downlink signal matches a phase shared in advance between the sensor controller and the active pen, and outputting, when it is determined that the phases match, 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.

Inventors

• Masayuki Miyamoto
• Hideyuki Hara

Assignees

• WACOM CO., LTD.

Dates

Publication Date

20260512

Application Date

20241203

Priority Date

20200907

Claims (9)

1. 1 . A method performed by a sensor controller, comprising: detecting, in a plurality of sensor electrodes, a downlink signal having a predetermined frequency or a predetermined waveform transmitted from an active pen; comparing a phase of the detected downlink signal and a phase shared in advance between the sensor controller and the active pen; and outputting, responsive to a result of the comparison of the phases, a position of the active pen based on the downlink signal detected in the plurality of sensor electrodes.
2. 2 . The method according to claim 1 , comprising: not outputting the position of the active pen, depending on the result of the comparison of the phases.
3. 3 . The method according to claim 1 , wherein the downlink signal transmitted from the active pen includes a predetermined waveform portion shared in advance between the sensor controller and the active pen, and the method comprises comparing the phase of the predetermined waveform portion included in the downlink signal and the phase shared in advance between the sensor controller and the active pen.
4. 4 . The method according to claim 3 , wherein the predetermined waveform portion is a portion resulting from the active pen modulating predetermined data shared in advance between the sensor controller and the active pen.
5. 5 . The method according to claim 4 , wherein the predetermined data is any one of a preamble, a start bit, or a stop bit.
6. 6 . The method according to claim 4 , wherein the result of the comparison of the phases is one of: a first result when the predetermined data is included in a symbol sequence obtained by demodulating the downlink signal, and a second result when said symbol sequence includes inverted data that is a part corresponding to the predetermined data in the symbol sequence obtained by demodulating the downlink signal.
7. 7 . The method according to claim 6 , comprising: performing two-way communication in synchronization with the active pen; and determining whether or not the predetermined data or the inverted data is included in the symbol sequence obtained by demodulating the downlink signal at a timing in which the predetermined data is included in the downlink signal.
8. 8 . The method according to claim 1 , comprising: receiving the downlink signal at each of a plurality of reception units; and comparing, for each of the plurality of reception units, the phase of the downlink signal detected at the reception unit and the phase shared in advance between the sensor controller and the active pen.
9. 9 . The method according to claim 8 , comprising: deriving a plurality of positions based on reception level values of the downlink signal in the plurality of sensor electrodes; allocating the plurality of derived positions to the plurality of reception units; and connecting one sensor electrode closest to the derived position to the allocated reception unit.

Description

BACKGROUND Technical Field The present disclosure relates to a method of palm rejection and a sensor controller. Description of the Related Art A position detector is known that supports pen input by an active pen. The active pen is an electronic pen configured to transmit a downlink signal from a pen tip electrode provided at a pen tip. The position detector attempts to detect the downlink signal in a plurality of sensor electrodes arranged in a touch surface and, based on the downlink signal detection, detects an instruction position that is pointed to by the active pen. The downlink signal is also transmitted to the body of a user holding the active pen, through a housing of the active pen. Therefore, the downlink signal is transmitted not only from the pen tip electrode but also from the palm of the user. The downlink signal transmitted from the palm is also detected by the sensor electrodes when the user puts the hand on the touch surface. The position detected on the basis of the result of this detection does not properly reflect the instruction position of the active pen, and the position needs to be excluded from the instruction position of the active pen. Hereinafter, the exclusion of the contact position of the palm from the instruction position of the active pen will be referred to as “palm rejection.” An example of a technique for performing the palm rejection is disclosed in PCT Patent Publication No. WO2018/225204 (hereinafter, referred to as Patent Document 1). In the technique, a detection result of a touch by a finger is combined with a reception result of a downlink signal to determine whether the detected position of the downlink signal is a contact position of the palm or an instruction position of the active pen. The contact position of the palm is excluded from the instruction position of the active pen on the basis of the result of the determination. However, the result of touch detection is necessary in the palm rejection described in Patent Document 1. Therefore, the technique cannot be executed in a mode in which the touch detection is stopped and only the detection of the active pen is performed (pen only mode). In addition, to properly determine the contact position of the palm in the palm rejection described in Patent Document 1, the area of a region detected based on the contact by the palm in the touch detection needs to be wide enough so that it can be distinguished from a region detected based on a normal contact by a finger. Therefore, the contact position cannot be properly determined when the touch by the palm is light so as to be detected only in a (narrow) region, which cannot be distinguished from a region detected based on a normal contact by a finger. BRIEF SUMMARY Therefore, an aspect of the present disclosure is to provide a method of palm rejection and a sensor controller that can exclude a contact position of a palm from an instruction position of an active pen, which will not rely on a detection result of a detection process, such as a touch detection process, other than the detection process of detecting the active pen. The present disclosure provides a method of palm rejection 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 method includes determining whether or not a phase of the detected downlink signal matches a phase shared in advance between the sensor controller and the active pen, and outputting, responsive to a determination that the phases match, 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. The present disclosure provides a sensor controller that is connected to a plurality of sensor electrodes and that detects a downlink signal having a predetermined frequency or a predetermined waveform transmitted from an active pen. The sensor controller determines whether or not a phase of the detected downlink signal matches a phase shared in advance between the sensor controller and the active pen, and outputs, responsive to a determination that the phases match, 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. Assuming that the human body is not sufficiently grounded, the downlink signal detected through the human body is a signal with a phase inverted from the phase of the downlink signal detected through the pen tip electrode. According to the present disclosure, because the phase of the downlink signal is determined, it is possible to discern the position derived on the basis of the downlink signal detected through the human body. Therefore, the contact position of the palm can be excluded from the instruction position of the active pen, without having to rely on a result of a detection process, such as a touch detection process, other than the detection process of de