Display Panel Photo Sensor Reset for External Light Accuracy
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Solution Overview
Problem
Existing display devices face challenges in accurately measuring external light incident on photo sensors due to interference from internal light from adjacent pixels, which affects the accuracy of functions like luminance adjustment and biometric authentication.
Innovation Solution
The display device incorporates a substrate design with specific control lines and circuits to manage emission and reset signals, along with a readout circuit for differential amplification, ensuring a longer reset period relative to sensing periods to minimize internal light interference and enhance photo sensor accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If photo sensor sensing is performed during normal operation, then biometric authentication and luminance control functions are enabled, but measurement precision deteriorates due to internal light interference from adjacent pixels
Solution Approach 1:
The patent applies preliminary action by performing a reset operation on the photo sensor before the sensing period. Specifically, a reset signal is applied to the photo sensor during a reset period that precedes the sensing period, initializing the sensor to a known state and eliminating residual charges from internal light. This preliminary reset action ensures that subsequent measurements of external light are not contaminated by previous internal light effects, thereby enabling accurate biometric authentication and luminance control functions.
2Measurement precision
If sensing period is extended to improve measurement accuracy, then external light measurement precision improves, but reset period must be sufficiently long to prevent internal light interference
Solution Approach 1:
The patent implements periodic action by establishing a cyclic sequence of reset periods and sensing periods. The photo sensor undergoes periodic reset operations followed by periodic sensing operations. This periodic alternation ensures that each sensing period is preceded by a reset period, systematically eliminating internal light interference while maintaining continuous operation. The regular cycling between reset and sensing states enables sustained accurate measurements without requiring excessively long individual reset 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
This approach improves the accuracy of light sensing by the photo sensor, enabling precise control of display luminance and biometric functions by effectively mitigating internal light interference.
Implementation Method 1
a light receiving element which receives a reset voltage in response to the reset control signal of a turn-on level
Implementation Method 2
a readout circuit which differentially amplifies and outputs voltages of the sensing line respectively sensed in response to a first sampling signal and a second sampling signal
Data Source
AI summary
A display device includes a display panel in pixel rows are disposed; an emission driving circuit which supplies an emission control signal to pixels positioned in a first image display area, supplies the emission control signal to pixels positioned in a second image display area, and supplies the emission control signal of a turn-off level to pixel rows positioned in a black area between the first and second image display areas; a reset circuit which supplies a reset control signal to photo sensors positioned in the black area during a reset period; and a readout circuit which senses the photo sensors based on a cycle corresponding to a sensing period, where a length of a reset period during which the reset control signal of the turn-on level is inputted is equal to or greater than twice a length of the sensing period.