OLED Display Panel Light Detection Input Mode
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Solution Overview
Problem
Conventional input interfaces, such as keyboards and mice, are inadequate for rapid data transmission in modern electronic commerce, prompting the need for alternative input modes like touch panels, which face challenges due to light sensitivity issues with amorphous silicon thin film transistors used in prior art touch panels.
Innovation Solution
An organic light-emitting display (OLED) device with a display and input mode, incorporating a driving unit, capacitor, light-emitting diode, light-detecting unit, and detecting unit, where the light-detecting unit senses reflected light to determine input signals, and can be implemented using LTPS TFTs to reduce light sensitivity issues.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a-Si TFTs are used to form photodiodes in touch panels, then the panel can sense reflected light for fingerprint recognition, but the leakage current becomes sensitive to light causing instability
Solution Approach 1:
The patent extracts the light-sensing function from the a-Si TFT-based photodiode structure and implements it separately using a dedicated photodiode layer coupled with a transistor switch. This separates the light detection function from the signal amplification function, allowing the a-Si TFT to be used for amplification without being directly exposed to light, thus eliminating the light sensitivity issue while maintaining fingerprint recognition capability
Solution Approach 2:
The patent introduces an intermediary structure consisting of a photodiode layer and a transistor switch that mediates between the incident light and the a-Si TFT amplification circuit. The photodiode converts optical signals to electrical signals, and the transistor switch controls the coupling to the a-Si TFT, preventing direct light exposure to the leakage current-sensitive a-Si TFT while still enabling light-based detection
2Adaptability or versatility
If touch panel functionality is added to display device, then input capability is improved, but device complexity increases
Solution Approach 1:
The patent implements multi-functionality by designing a single pixel unit that can operate in both display mode and input mode. The same pixel structure with the added photodiode and switch components serves dual purposes: displaying images through the light-emitting element and detecting touch input through the photodiode's light sensing capability, thereby reducing overall device complexity compared to separate display and input panels
Solution Approach 2:
The patent merges the display function and input detection function into a single integrated pixel unit. The light-emitting element and photodiode are combined within the same pixel structure, sharing common components such as the transistor switch and connection to the data line and scan line, thus reducing the overall complexity compared to having separate display and input panels
3Speed
If light-detecting unit is activated continuously, then input detection responsiveness is improved, but power consumption increases
Solution Approach 1:
The patent implements periodic action by using the transistor switch to periodically activate the photodiode's light-detecting function only when input mode is required, rather than keeping it continuously active. The switch is controlled by scan signals that periodically enable the photodiode to sense reflected light during specific time windows, maintaining responsive input detection while significantly reducing power consumption during display-only operation
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
Enables efficient data input by sensing light reflected from objects, improving data transmission rates and reducing power consumption by enabling light detection only during input mode, while maintaining display functionality.
Implementation Method 1
the light-detecting unit senses the light reflected by a finger, and then a readout amplifier determines a fingerprint
Implementation Method 2
a light-emitting diode, a light-detecting unit, and a detecting unit
Data Source
AI summary
A display panel for OLED device having a display mode and an input mode. The display panel comprises a driving unit, a capacitor, a light-emitting diode, a light-detecting unit, and a detecting unit. The driving unit has a control electrode coupled to a first node, a first electrode coupled to a first voltage source, and a second electrode. The capacitor and the light-detecting unit are coupled between the first node and the first voltage source. The light-emitting diode is coupled between the control electrode of the driving unit and a second voltage source. In the input mode, the detecting unit detects a voltage at the first node.