In-Cell Touch Display Power Modulation for Parasitic Capacitance
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Solution Overview
Problem
The integration of a touch sensor within an organic light emitting diode display panel increases parasitic capacitance, leading to degraded touch sensitivity and accuracy due to the proximity of the touch sensor to display driving electrodes and lines.
Innovation Solution
A time-division driven in-cell touch display device with a power modulation circuit that includes RLC circuits to modulate power voltages at different frequencies, reducing parasitic capacitance effects by applying modulation voltages with specific cycles and amplitudes during touch and display periods.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the touch sensor is embedded in the display panel, then the device thickness is reduced and manufacturing is simplified, but parasitic capacitance increases leading to degraded touch sensitivity
Solution Approach 1:
The patent applies time-division multiplexing to alternately drive touch electrodes and display electrodes during specific time periods. By activating touch electrodes only during designated touch detection periods and keeping them inactive during display periods, the system reduces parasitic capacitance interference while maintaining integrated in-cell touch functionality, thus preserving touch sensitivity without increasing device thickness
2Device complexity
If the touch sensor is located close to display driving electrodes, then the in-cell integration is achieved, but parasitic capacitance between touch sensor and display electrodes increases significantly
Solution Approach 1:
The patent implements periodic activation of touch electrodes during specific touch detection periods while keeping them inactive during display periods. This time-division approach allows the touch sensor to be physically integrated close to display electrodes without continuous parasitic capacitance interference, as the touch electrodes are only active when needed for touch detection
Solution Approach 2:
The patent segments the driving periods into distinct touch detection periods and display periods. By dividing the operational timeline into separate segments for touch electrode activation and display electrode activation, the system reduces overlapping parasitic capacitance effects while maintaining the physical integration benefits of in-cell touch technology
3Measurement precision
If modulation voltages are applied during touch period, then parasitic capacitance effects are reduced, but power consumption increases
Solution Approach 1:
The patent applies modulation voltages to touch electrodes only during specific touch detection periods rather than continuously. This periodic application of modulation voltages reduces parasitic capacitance effects during critical touch detection moments while minimizing overall power consumption by keeping touch electrodes inactive during display periods
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
Improves touch sensitivity and accuracy by minimizing the impact of parasitic capacitance, maintaining image quality, and reducing power consumption.
Implementation Method 1
a first RLC circuit having a first resonance frequency and a second RLC circuit having a second resonance frequency that is different from the first resonance frequency, wherein the first RLC circuit modulates a high potential power voltage into a high potential modulation voltage of the first resonance frequency and outputs the high potential modulation voltage to the driving transistor during the touch period, and the second RLC circuit modulates a low potential power voltage that is less than the high potential power voltage into a low potential modulation voltage of the second resonance frequency during the touch period and outputs the low potential modulation voltage to the light emitting device
Data Source
AI summary
An in-cell touch display device is presented herein that features an increased accuracy of touch sensitivity and touch recognition. The in-cell touch display device includes a display panel including a transistor formation layer with a driving transistor, a light emitting element layer on the transistor formation layer that includes a light emitting element, and a plurality of touch electrodes in the transistor formation layer or the light emitting element that are driven during a display period and a touch period in a time-division manner, a touch driving circuit for supplying a touch driving voltage to a touch electrode, and a power modulation circuit including a first RLC circuit and a second RLC circuit each including a resistor, an inductor, and a capacitor connected to a corresponding one of a high potential power line that supplies the driving transistor and a low potential power line that supplies a cathode electrode.