OLED Anode Reset Circuit for Low-Noise Touch Sensing
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Solution Overview
Problem
Noise from display circuitry interferes with touch sensor functionality, particularly at higher refresh rates, causing inaccurate touch sensing operations.
Innovation Solution
Implementing circuitry with an anode reset transistor coupled to an anode reset voltage line, a light-emitting diode, and a storage capacitor, along with specific transistor configurations and scan pulse timing to reduce anode reset noise during touch sensing operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If anode reset transistor is activated during touch sensing operations, then display circuitry can reset the anode of the light-emitting diode, but noise from the anode reset operation interferes with touch sensor functionality
Solution Approach 1:
The patent divides the display panel into distinct regions with different cathode configurations: continuous cathode regions for display pixels and disconnected cathode regions for touch sensor regions. This segmentation allows independent control of electrical characteristics in different areas, enabling touch sensing operations to proceed without interference from anode reset noise in display regions.
Solution Approach 2:
The patent extracts the cathode function from the touch sensor region by implementing disconnected cathode portions that are electrically isolated from the main cathode layer. This separation removes the harmful electrical coupling between the anode reset transistor and the touch sensor electrodes, eliminating noise interference while preserving display functionality.
2Speed
If refresh rate is increased, then display update speed improves, but noise interference with touch sensing increases
Solution Approach 1:
By segmenting the cathode into continuous and disconnected portions, the patent enables independent timing control. The disconnected cathode portions can remain electrically isolated during touch sensing regardless of refresh rate, allowing high-speed display updates without proportionally increasing touch sensor noise interference.
Solution Approach 2:
The patent implements periodic activation of the anode reset transistor synchronized with the display refresh cycle. During touch sensing periods, the anode reset transistor remains inactive, creating noise-free windows for accurate touch detection. This periodic control allows high refresh rates while maintaining touch sensing accuracy through temporal separation of noisy and quiet operations.
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
Reduces cathode rippling and mitigates interference between display and touch sensor components, enhancing touch sensing accuracy and performance.
Implementation Method 1
a light-emitting diode
Implementation Method 2
a light-emitting diode
Implementation Method 3
a storage capacitor coupled to a gate terminal of the drive transistor
Data Source
AI summary
An electronic device may include display and touch circuitry. The circuitry may include an array of pixels. Each pixel in the array may include at least a light-emitting diode, a drive transistor coupled in series with the light-emitting diode, a storage capacitor coupled to a gate terminal of the drive transistor, and an anode reset transistor configured to reset an anode of the light-emitting diode and coupled to an anode reset voltage line. The light-emitting diode may have a cathode that is capacitively coupled to one or more touch sensor electrodes. The anode reset transistor may be activated while the touch sensor electrodes are performing touch sensing operations during a vertical blanking period. The cathode can be formed from a cathode layer driven to a ground voltage and disconnected from one or more electrically floating cathode layer portions elevated relative to the cathode layer by floating cathode support structures.