US-12624967-B2 - Location detection device and electronic apparatus

US12624967B2US 12624967 B2US12624967 B2US 12624967B2US-12624967-B2

Abstract

A location detection device according to the present disclosure includes an electro-magnetic resonance (EMR) sensor arranged to overlap with a display device, and a sensor controller connected to the EMR sensor. The EMR sensor includes a plurality of loop coils arranged side by side in a first direction of a panel surface. The sensor controller, in operation, detects a location of an electromagnetic induction pen, based on an alternating current generated by using both of a first alternating current output from a first loop coil located proximate one end of the plurality of loop coils in the first direction, and a second alternating current output from a second loop coil located on an opposite side of a center of the panel surface in the first direction from the first loop coil. The accuracy of location detection for an electromagnetic induction pen, performed by using the EMR sensor improved.

Inventors

Koji Noguchi
Kei Dobashi
Kota Imanishi

Assignees

WACOM CO., LTD.

Dates

Publication Date: 20260512
Application Date: 20250522
Priority Date: 20221128

Claims (6)

1 . A location detection device comprising: a sensor arranged to overlap with a display device; and a sensor controller connected to the sensor, wherein the sensor includes a plurality of loop coils arranged side by side in a first direction of a panel surface, wherein the sensor controller, in operation, detects a location of an electromagnetic induction pen, based on a third alternating current generated by using both a first alternating current output from a first loop coil located proximate one end of the plurality of loop coils in the first direction and a second alternating current output from a second loop coil located on an opposite side of a center of the panel surface in the first direction from the first loop coil and wherein noise derived from a gate line and superposed on the first alternating current of the first loop coil is cancelled by noise derived from the gate line and superposed on the second alternating current of the second loop coil.
2 . The location detection device according to claim 1 , wherein the sensor controller, in operation, generates the third alternating current by adding the first alternating current and the second alternating current.
3 . The location detection device according to claim 1 , wherein the sensor controller includes a first low-pass filter and a second low-pass filter, and generates the third alternating current by adding the first alternating current that has passed through the first low-pass filter and the second alternating current that has passed through the second low-pass filter.
4 . The location detection device according to claim 3 , wherein a cutoff frequency of each of the first low-pass filter and the second low-pass filter is set to a frequency higher than a frequency of an alternating magnetic field emitted from the electromagnetic induction pen.
5 . The location detection device according to claim 1 , wherein the sensor controller detects the location of the electromagnetic induction pen, based on the third alternating current when the location of the electromagnetic induction pen has already been detected, and detects the location of the electromagnetic induction pen, based on the first alternating current when the location of the electromagnetic induction pen has not yet been detected.
6 . An electronic apparatus comprising: a display device; and a location detection device, wherein the location detection device includes: a sensor arranged to overlap with the display device, and a sensor controller connected to the sensor, and wherein the sensor includes a plurality of loop coils arranged side by side in a first direction of a panel surface, wherein the sensor controller, in operation, detects a location of an electromagnetic induction pen, based on a third alternating current generated by using both a first alternating current output from a first loop coil located proximate one end of the plurality of loop coils in the first direction, and a second alternating current output from a second loop coil located on an opposite side of a center of the panel surface in the first direction from the first loop coil, and wherein noise derived from a gate line and superposed on the first alternating current of the first loop coil is cancelled by noise derived from the gate line and superposed on the second alternating current of the second loop coil.

Description

BACKGROUND Technical Field The present disclosure relates to a location detection device and an electronic apparatus, and more particularly to a location detection device having a sensor arranged to overlap with a display device, and an electronic apparatus including such a location detection device. Description of the Related Art Some electronic apparatuses that support pen input, such as smartphones and tablet terminals, are configured to detect the location of an electromagnetic induction pen by using an electro-magnetic resonance (EMR) method, which is a type of electromagnetic induction method. In this type of electronic apparatus, a display device such as a liquid crystal display or an organic electro-luminescence (EL) display is arranged to overlap with an EMR sensor including a plurality of loop coils. Hereinafter, if a direction parallel to one side of a panel surface (touch surface) of the electronic apparatus (e.g., a horizontal direction as seen from a user) is called an X direction, and a direction perpendicular to the X direction (e.g., a depth direction as seen from a user) is called a Y direction, the plurality of loop coils includes a plurality of X-side loop coils that each extend in the Y direction and are arranged side by side in the X direction, and a plurality of Y-side loop coils that each extend in the X direction and are arranged side by side in the Y direction. Patent Document 1 discloses an example of an electronic apparatus having such a configuration. PRIOR ART DOCUMENT Patent Document Patent Document 1: JP 2022-145907A BRIEF SUMMARY Technical Problem The inventors of the present application actually manufactured an electronic apparatus having a display device and an EMR sensor arranged to overlap with each other, and discovered that noise originating from gate lines of the display device has been observed in the alternating current output from some of a plurality of X-side loop coils located near either end of the panel surface while checking the characteristics of the EMR sensor. Such noise reduces the accuracy of location detection of the electromagnetic induction pen, and therefore needs to be reduced. Accordingly, embodiments of the present disclosure provide a location detection device and electronic apparatus that can improve the accuracy of detecting the location of an electromagnetic induction pen by using an EMR sensor arranged to overlap with a display device. Technical Solution A location detection device according to the present disclosure is a location detection device that includes a sensor arranged to overlap with a display device and a sensor controller connected to the sensor, and the sensor includes a plurality of loop coils arranged side by side in a first direction of a panel surface, and the sensor controller, in operation, detects the location of an electromagnetic induction pen based on a third alternating current generated by using both a first alternating current output from a first loop coil that is located proximate one end of the plurality of loop coils in the first direction, and a second alternating current output from a second loop coil that is located on an opposite side of a center of the panel surface in the first direction from the first loop coil. An electronic apparatus of the present disclosure is an electronic apparatus including a display device and a location detection device, and the location detection device includes a sensor arranged to overlap with the display device and a sensor controller connected to the sensor, and the sensor includes a plurality of loop coils arranged side by side in a first direction of a panel surface, and the sensor controller, in operation, detects the location of an electromagnetic induction pen based on a third alternating current generated by using both a first alternating current output from a first loop coil located proximate one end of the plurality of loop coils in the first direction, and a second alternating current output from a second loop coil located on the opposite side of the center of the panel surface in the first direction from the first loop coil. Advantageous Effect According to the present disclosure, the accuracy of detecting the location of an electromagnetic induction pen by using an EMR sensor arranged to overlap with a display device can be improved. BRIEF DESCRIPTION OF DRAWINGS FIG. 1 is a diagram illustrating the configuration of an electronic apparatus 1 according to an embodiment of the present disclosure. FIG. 2 is a diagram illustrating the detailed configuration of an EMR sensor 15 and a sensor controller 20 illustrated in FIG. 1. FIG. 3 is a schematic diagram illustrating how a display device 13 and some of loop coils LCx in the EMR sensor 15 are arranged to overlap with each other. FIG. 4 is a diagram illustrating measurement results of noise originating from a gate line GL observed in each of the loop coils X0 and X72. FIG. 5 is a diagram illustrating simulation results o