OLED Pixel Circuit Touch Accuracy via Modulated Light
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Solution Overview
Problem
Optical touch screen panels for OLED display panels face accuracy issues due to changes in light intensity over time, affecting the determination of touch positions.
Innovation Solution
A pixel circuit comprising a light emitting element, a pixel driving circuit, and an optical modulation circuit, where the optical modulation circuit drives the light emitting element to emit modulated light under control of touch sensing signals, and the pixel driving circuit emits light for display, with the optical sensitive sensors detecting this modulated light to improve touch position accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If active modulation light is used to achieve touch function, then the touch screen can utilize the OLED panel's own light emission, but the light intensity changes over time causing inaccurate touch position determination
Solution Approach 1:
The patent applies periodic action by using a modulation signal with a specific frequency to drive the light emitting element during touch detection. The optical modulation circuit modulates the light emission in a periodic manner, allowing the optical sensitive sensor to distinguish modulated light from ambient light through frequency discrimination. This resolves the contradiction by maintaining consistent touch detection accuracy despite changes in overall light intensity over time.
Solution Approach 2:
The patent introduces an intermediary approach by using modulation and demodulation processes. The optical modulation circuit acts as an intermediary that encodes touch information into light intensity variations at a specific frequency, and the optical sensitive sensor with demodulation capability extracts this information. This intermediary mechanism allows accurate touch position determination independent of the absolute light intensity level.
2Device complexity
If the light emitting element is used for both display and touch detection, then the structure is simplified, but the light intensity varies during different display states affecting touch detection accuracy
Solution Approach 1:
The patent implements universality by making the light emitting element serve dual functions: display through the pixel driving circuit and touch detection through the optical modulation circuit. The same light emitting element is controlled by different circuits for different purposes, eliminating the need for separate light sources and simplifying the overall structure while maintaining touch detection accuracy through frequency-based discrimination.
Solution Approach 2:
The periodic modulation of light emission during touch detection phases allows the system to distinguish touch-related light variations from display-related light variations. By activating the optical modulation circuit only during touch detection and using frequency-modulated signals, the system achieves accurate touch position determination regardless of the display content or ambient light conditions.
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
The solution stabilizes light emission luminance during touch operations, enhancing the accuracy of touch detection by isolating modulated light from ambient light and maintaining consistent touch detection across varying light conditions.
Implementation Method 1
a light emitting element, configured to emit light in term of a driving current provided by the pixel driving circuit
Data Source
AI summary
A pixel circuit, an array substrate, a display panel, a display device, and a display driving method are provided. The pixel circuit includes a light emitting element, a pixel driving circuit, and an optical modulation circuit; in a touch stage, turning off the pixel driving circuit, driving the light emitting element to emit a modulated light of a first gray scale by the optical modulation circuit; and in a display stage, turning off the optical modulation circuit, and driving the light emitting element to emit light for display by the pixel driving circuit.