Touch Panel Frequency Control for Active Pen Display Noise
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Solution Overview
Problem
Existing position detection systems in tablet terminals face challenges with active pens due to display noise interference, leading to deteriorated rendering quality and malfunction, especially when communication is limited to noise-free periods, affecting real-time data transmission and sensor sensitivity.
Innovation Solution
A position detection system that suppresses specific frequency components in capacitive noise using a touch sensor and display device configuration, allowing communication between the active pen and touch sensor to occur independently of pixel electrode driving, using a predetermined frequency band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If communication is limited to noise-free periods, then display noise interference is reduced, but real-time data transmission capability deteriorates
Solution Approach 1:
The patent segments the frequency spectrum into multiple bands, allocating the noise-free period for uplink communication and the noise period for downlink communication. This frequency-domain segmentation allows simultaneous operation without interference, resolving the contradiction between avoiding noise and maintaining real-time communication.
Solution Approach 2:
The system implements periodic communication cycles where the touch sensor transmits uplink signals during noise-free periods and receives downlink signals during noise periods. This periodic action pattern ensures both noise avoidance and real-time data exchange by alternating between transmission and reception phases.
2Object-affected harmful factors
If uplink signal transmission time is allocated exclusively at the beginning of noise-free period, then noise interference is minimized, but downlink signal transmission time becomes insufficient
Solution Approach 1:
The patent divides the communication period into distinct segments: uplink transmission occurs at the beginning of the noise-free period, while downlink transmission occurs during the subsequent noise period. This temporal segmentation ensures adequate time for both directions of communication without compromising either function.
Solution Approach 2:
The system establishes a periodic communication cycle where uplink and downlink transmissions are alternately scheduled. This periodic structure guarantees that downlink transmission time is not sacrificed but rather integrated into the overall communication rhythm, maintaining sufficient time for pressure data transmission.
3Reliability
If display noise occurs during noise-free period, then communication reliability is improved, but sensor sensitivity deteriorates
Solution Approach 1:
The patent segments the operational timeline into noise-free periods for uplink transmission and noise periods for downlink reception. This segmentation ensures that the sensor operates in a quiet environment during reception phases, maintaining high sensitivity while achieving reliable communication through the structured alternation of transmission and reception windows.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach prevents deterioration of rendering quality by minimizing display noise interference, ensuring reliable real-time data transmission and maintaining sensor sensitivity, thus improving the accuracy and reliability of active pen operations.
Implementation Method 1
The active pen communicates with the touch sensor using a frequency included in a predetermined frequency band by a charge induced in the sensor electrode
Implementation Method 2
capacitive noise that occurs in the sensor electrode due to a voltage vibration in an interconnect in the display device caused by driving of the plurality of pixel electrodes
Data Source
AI summary
A position detection system includes a display device that displays image data by driving pixel electrodes, and a touch panel including a sensor electrode and a touch sensor. An active pen communicates with the touch sensor using a frequency included in a frequency band. The display device suppresses a frequency component in the frequency band in capacitive noise that occurs in the sensor electrode due to a voltage vibration in an interconnect in the display device caused by driving of the pixel electrodes. The display device selectively operates in either of a first operation mode in which driving of the pixel electrodes suppresses the frequency component included in the capacitive noise that occurs in the sensor electrode, and a second operation mode in which driving of the pixel electrodes does not suppress the frequency component included in the capacitive noise that occurs in the sensor electrode.