In-Display Fingerprint Sensing Pixel Reset With Layered Voltages
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Solution Overview
Problem
Existing display devices face challenges in smoothly resetting light receiving pixels before exposure to light, which affects the accuracy and efficiency of fingerprint sensing functions.
Innovation Solution
The display device incorporates light emitting pixels and light receiving pixels with specific voltage configurations and transistor controls, including a reset line and fingerprint scan line, to ensure smooth resetting of light receiving pixels before exposure to light, utilizing different voltage levels and transistor operations to maintain a forward bias state.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If light receiving pixels are exposed to light for fingerprint sensing, then fingerprint sensing function is enabled, but the pixels may not be properly reset affecting sensing accuracy
Solution Approach 1:
The reset transistor is activated before the light receiving pixel is exposed to light to clear any residual charge from the light receiving element. This preliminary resetting action ensures that the pixel starts each sensing cycle with a clean state, improving fingerprint sensing accuracy by preventing residual charge interference.
Solution Approach 2:
The patent implements a controlled feedback mechanism where the reset transistor is selectively activated based on the sensing cycle timing. The reset operation is triggered by control signals that coordinate with the light emission and sensing timing, ensuring proper reset without requiring complex continuous control circuits.
2Manufacturing precision
If multiple voltage lines are used to control light receiving pixels, then reset precision is improved, but the circuit complexity increases
Solution Approach 1:
The patent applies different voltage levels to different parts of the light receiving pixel circuit at different times. The first voltage line provides a first voltage level for resetting the light receiving element, while the second voltage line provides a second voltage level for maintaining the light receiving transistor state. This localized voltage control enables precise reset operations without requiring a complex multi-voltage system throughout the entire display.
Solution Approach 2:
The voltage control function is segmented into separate dedicated lines: one voltage line specifically for reset operations and another for maintaining transistor state. This segmentation allows each voltage line to be optimized for its specific function, achieving precise control with a relatively simple two-line configuration rather than requiring multiple general-purpose voltage lines.
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 configuration allows for accurate and efficient fingerprint sensing by ensuring that light receiving pixels are properly reset, enhancing the reliability and precision of fingerprint recognition.
Implementation Method 1
Each of the light receiving pixels may include a light receiving element
Data Source
AI summary
A display device includes light emitting and receiving pixels, a reset line, a fingerprint scan line, a fingerprint sensing line, and first and second voltage lines in a display region. Each light receiving pixel includes a light receiving element including a first electrode and a second electrode connected to the second voltage line, a sensing transistor connecting the first electrode to the fingerprint sensing line according to a fingerprint scan signal applied to the fingerprint scan line and a reset transistor to connect the first voltage line to the first electrode according to a reset signal applied to the reset line. A first voltage applied to the first voltage line is greater than a second voltage applied to the second voltage line, and a third voltage applied to the fingerprint sensing line is greater than the second voltage and smaller than the first voltage.