Optical Sensor Circuit for Stable Ambient Light Detection in LCDs
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Solution Overview
Problem
Liquid crystal display devices consume high power due to constant backlight brightness, even in low peripheral light environments, leading to increased power consumption and potential degradation in visual perception.
Innovation Solution
An optical sensor with at least two first transistors coupled in parallel between an output line and base power supply, and additional second transistors between the first transistors and a voltage source, allows for stable detection of peripheral light intensity, enabling control of backlight brightness and reducing power consumption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single transistor is used for detecting peripheral light, then the mounting space is minimized, but the output current stability is insufficient
Solution Approach 1:
The optical sensor is divided into two functional segments: first transistors (T1, T2) for light detection and second transistors (T3, T4) for signal compensation. This segmentation allows each transistor group to perform its specific function optimally, with the first transistors detecting light intensity and the second transistors compensating for variations, thereby improving output stability without requiring a completely complex new structure
Solution Approach 2:
The patent combines multiple transistors into an integrated sensor structure where first and second transistors work together in a unified circuit configuration. The first transistors are coupled in parallel between output line and base power supply, while second transistors are positioned between the first transistors and voltage source, creating a merged structure that achieves stable output current while maintaining compact integration
2Use of energy by moving object
If constant brightness is supplied to each pixel unit, then the visual quality is maintained, but the power consumption increases significantly
Solution Approach 1:
The backlight brightness is changed from a static constant value to a dynamic value that adjusts according to detected peripheral light intensity. The optical sensor continuously monitors ambient light levels and the backlight driver dynamically modifies backlight brightness accordingly, enabling the system to consume less power in low-light environments while maintaining appropriate visual quality across different lighting conditions
Solution Approach 2:
A feedback loop is established where the optical sensor detects peripheral light intensity and provides this information to the backlight driver, which then adjusts the backlight brightness. This closed-loop feedback system ensures that visual quality is maintained by automatically compensating for changes in ambient lighting conditions while optimizing power consumption by reducing backlight intensity when sufficient ambient light is present
3Area of stationary object
If the optical sensor is positioned at the opening part of the black matrix, then the mounting space is minimized, but the detection precision may be affected
Solution Approach 1:
The patent applies local quality by positioning the optical sensor specifically at the opening part of the black matrix where space is constrained, but compensates for the potential precision loss through the use of multiple first transistors coupled in parallel. This configuration allows the sensor to maintain compact positioning while achieving sufficient detection precision through the combined signal from multiple transistor elements
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 optical sensor effectively reduces power consumption by adjusting backlight brightness based on peripheral light intensity, while maintaining visual quality by preventing brightness reduction when light intensity exceeds a certain threshold.
Implementation Method 1
at least two first transistors coupled in parallel between an output line and base power supply for detecting an intensity of peripheral light... The first transistors may be adapted to control an amount of current flowing into the output line corresponding to the intensity of peripheral light incident on their gate electrodes
Data Source
AI summary
An optical sensor for detecting peripheral light including: at least two first transistors coupled in parallel between an output line and base power supply for detecting an intensity of peripheral light; and at least two second transistors positioned at a side of the first transistors and between the first transistors and a voltage source.