# US 12,761,749 B2 · Capacitive screens and methods for interaction with a stylus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 12,761,749 B2 - Document ID: US12761749B2 - Status: Granted - Kind: B2 - Application number: 18/916,743 - Filed: 2024-10-16 - Published: 2025-02-27 - Granted: 2026-10-13 - Earliest claimed: 2022-06-24 - Applicants: Chipsemi Semiconductor (Ningbo) Co., Ltd. - Inventors: Yaoguo Zhang; Haifeng Shen; Bo Xia; Bo Nie; Congqing Yu; Guofan Cheng; Jui-Ming Ni - Web page: https://patentgrep.com/patent/US12761749B2 ## CPC - G06F 3/04162: {for exchanging data with external devices, e.g. smart pens, via the digitiser sensing hardware} - G06F 3/0441: {using active external devices, e.g. active pens, for receiving changes in electrical potential transmitted by the digitiser, e.g. tablet driving signals} - G06F 3/0442: {using active external devices, e.g. active pens, for transmitting changes in electrical potential to be received by the digitiser} - G06F 3/046: by electromagnetic means - G06F 2203/04101: 2.5D-digitiser, i.e. digitiser detecting the X/Y position of the input means, finger or stylus, also when it does not touch, but is proximate to the digitiser's interaction surface and also measures the distance of the input means within a short range in the Z direction, possibly with a separate measurement setup - G06F: ELECTRIC DIGITAL DATA PROCESSING (computer systems based on specific computational models G06N) ## Abstract The present application discloses a capacitive screen, a method for its interaction with a stylus, and a storage medium. The capacitive screen includes a touch control chip and a screen coil. The touch chip generates a first current signal, which the screen coil, integrated as a metal coil, converts into a first electromagnetic signal. This signal is sent to the stylus, which then returns a second electromagnetic signal to the screen coil. The screen coil converts this into a second current signal for the touch chip, which calculates the distance between the screen and stylus. This invention enables real-time distance monitoring and interaction between the screen and stylus with low cost and power consumption. ## Claims ### Claim 1 A capacitive screen, comprising: a touch control chip configured to generate a first current signal; and a screen coil operable to: generate a first electromagnetic signal based on the first current signal, transmit the first electromagnetic signal to a stylus, receive a second electromagnetic signal transmitted by the stylus, and convert the second electromagnetic signal into a second current signal; wherein the touch control chip is further configured to determine a quantitative distance between the capacitive screen and the stylus based on a magnitude or waveform characteristic of the second current signal. ### Claim 2 (depends on 1) The capacitive screen of claim 1, wherein the screen coil has a first end connected to the touch control chip to receive the first current signal and a second end connected to a reference potential. ### Claim 3 (depends on 2) The capacitive screen of claim 2, wherein the screen coil is configured to periodically transmit the first electromagnetic signal and periodically receive the second electromagnetic signal. ### Claim 4 (depends on 2) The capacitive screen of claim 2, further comprising a transmission metal line and a reception metal line, wherein the screen coil is positioned around the transmission metal line and the reception metal line, such that the screen coil is located at a periphery surrounding both the transmission metal line and the reception metal line, and wherein the screen coil is not connected to the transmission metal line and the reception metal line. ### Claim 5 (depends on 1) The capacitive screen of claim 1, wherein the first electromagnetic signal is configured to enable synchronization between the stylus and the capacitive screen when the stylus is positioned within a preset distance range relative to the capacitive screen. ### Claim 6 (depends on 5) The capacitive screen of claim 5, wherein the preset distance range is between a first preset distance at which the stylus can receive the first electromagnetic signal and a second preset distance less than the first preset distance. ### Claim 7 (depends on 5) The capacitive screen of claim 5, further comprising: a transmission metal line; a reception metal line; wherein the touch control chip is configured to: generate a first voltage signal and transmit the first voltage signal to the stylus through the transmission metal line when the distance between the stylus and the capacitive screen is less than or equal to a second preset distance; receive a second voltage signal from the stylus through the reception metal line; and determine real-time coordinates of the stylus based on magnitude of the second voltage signal. ### Claim 8 A capacitive screen, comprising: a touch control chip configured to generate a current signal; a screen coil integrated into the capacitive screen, wherein the screen coil is configured to: receive an electromagnetic signal from a stylus, generate a second electromagnetic signal based on the current signal, and transmit the second electromagnetic signal to the stylus. ### Claim 9 A method for operating a capacitive screen and a stylus, comprising: generating, by a screen coil integrated into the capacitive screen, a first electromagnetic signal based on a first current signal; transmitting the first electromagnetic signal to the stylus; receiving, by the screen coil, a second electromagnetic signal from the stylus in response to the first electromagnetic signal; converting the second electromagnetic signal into a second current signal; and determining a quantitative distance between the capacitive screen and the stylus based on a magnitude or waveform of the second current signal. ### Claim 10 A method for operating a capacitive screen and a stylus, comprising: receiving a third electromagnetic signal sent by the stylus and, upon receiving the third electromagnetic signal, generating a fourth electromagnetic signal based on a pre-obtained third current signal; sending the fourth electromagnetic signal to the stylus, enabling the stylus to determine actual distance between the capacitive screen and the stylus based on the fourth electromagnetic signal; wherein the fourth electromagnetic signal is generated by a screen coil integrated into the capacitive screen. ### Claim 11 A capacitive screen, comprising: at least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the following: generating, by a screen coil integrated into the capacitive screen, a first electromagnetic signal based on a first current signal; transmitting the first electromagnetic signal to a stylus; receiving, by the screen coil, a second electromagnetic signal from the stylus in response to the first electromagnetic signal; converting the received second electromagnetic signal into a second current signal; and determining a quantitative distance between the capacitive screen and the stylus based on a magnitude or waveform of the second current signal.