Optical Sensor Transistor Layout for LCD Power Reduction
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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 inefficiency.
Innovation Solution
An optical sensor system using multiple transistors in parallel between an output line and a base power supply, with additional compensation transistors, to detect peripheral light intensity and control backlight brightness, thereby reducing power consumption without a separate amplification circuit.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple transistors are coupled in parallel to detect peripheral light, then output current stability is improved, but mounting space increases
Solution Approach 1:
The patent positions transistors in different spatial dimensions - first transistors are placed at opening parts of the black matrix (utilizing vertical space above the matrix), while second transistors are positioned at sides overlapping with the black matrix. This three-dimensional arrangement allows multiple transistors to be integrated without proportionally increasing the planar mounting area, thus maintaining compact form factor while achieving stable output current through parallel configuration.
2Measurement precision
If compensation transistors are added to improve detection accuracy, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The compensation transistors serve multiple functions: they compensate for process variations in transistor characteristics, provide stable reference currents for the detection transistors, and enable accurate peripheral light detection. By integrating these compensation mechanisms within the same transistor network, the patent achieves high measurement precision without proportionally increasing device complexity, as the same structural elements serve both detection and compensation purposes.
3Measurement precision
If transistors are positioned at opening parts of black matrix, then peripheral light detection is improved, but mounting space is reduced
Solution Approach 1:
The patent divides the optical sensor into multiple segmented transistor units positioned at different opening parts of the black matrix. Each transistor segment detects light independently, and their outputs are combined to achieve stable peripheral light detection. This segmentation allows the sensor to utilize distributed spaces within the black matrix openings rather than requiring a single large area, thus improving detection capability while minimizing overall mounting space.
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 system stably generates sufficient output current to effectively detect peripheral light, reducing power consumption and maintaining visual quality by adjusting backlight brightness based on ambient light conditions.
Implementation Method 1
at least two first transistors positioned at an opening part of a black matrix and coupled in parallel between an output line and base power supply for detecting an intensity of peripheral light
Implementation Method 2
display desired images by controlling the amount of light transmitted through liquid crystal layers by utilizing the refractive index anisotropy of liquid crystal molecules
Implementation Method 3
utilizing the refractive index anisotropy of liquid crystal molecules
Data Source
Figure 1
Figure 2~3
Figure 4A~4B
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.