LED Backlight Control via Time-Division Multiplexing
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Solution Overview
Problem
Conventional LCD devices with LED backlight modules require numerous controllers to adjust brightness, leading to increased costs as the number of LEDs increases, making it essential to develop a method for effectively controlling light intensity while reducing manufacturing costs.
Innovation Solution
A light emitting device comprising a light emitting unit, a switching unit, a comparator unit, a charge storage unit, and a sensing unit, where the sensing unit adjusts electric charges and voltage based on light intensity, and the comparator unit controls the light emitting unit by comparing these values with a threshold voltage, offsetting background dark current effects to manage accumulating light energy without feedback control, thereby reducing circuit complexity and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of LEDs is increased to achieve better display image with true color, then the display quality is improved, but the number of controllers must increase as well hence the cost rises
Solution Approach 1:
The patent merges multiple control functions into a single controller by having it sequentially control different groups of LEDs (first group, second group, third group) at different time periods. This consolidation reduces the number of controllers from multiple (one per LED or group) to just one, thereby reducing cost while maintaining the ability to control tens to hundreds of LEDs for better display quality.
Solution Approach 2:
The patent implements periodic control by dividing LED control into different time periods (first time period, second time period, third time period) where different groups of LEDs are activated sequentially. This time-division multiplexing approach allows a single controller to manage multiple LED groups that would otherwise require multiple simultaneous controllers, reducing system complexity and cost.
2Illumination intensity
If the number of LEDs is increased to achieve better display image with true color, then the display quality is improved, but the manufacture cost rises
Solution Approach 1:
The patent merges multiple control functions into a single controller by having it sequentially control different groups of LEDs (first group, second group, third group) at different time periods. This consolidation reduces the number of controllers from multiple (one per LED or group) to just one, thereby reducing cost while maintaining the ability to control tens to hundreds of LEDs for better display quality.
Solution Approach 2:
The single controller is designed to perform multiple functions by controlling different groups of LEDs at different time periods. It can control the first group during the first time period, the second group during the second time period, and the third group during the third time period, making it a universal control unit that replaces multiple specialized controllers, thus reducing manufacture cost.
3Measurement precision
If feedback control on light intensity is implemented, then the brightness control precision is improved, but the circuit structure complexity and cost increase
Solution Approach 1:
The patent employs a light sensing circuit that automatically senses the light intensity of the light emitting unit and provides feedback to the controller without requiring additional complex feedback control circuits. The controller uses this sensed information to automatically adjust the control signals, enabling the system to self-regulate brightness based on actual light output, thus achieving precision control with minimal additional circuitry.
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 solution allows for precise control of light intensity and energy accumulation, reducing the number of circuit elements and lowering manufacturing costs by eliminating the need for multiple controllers, while effectively managing background dark current impacts.
Implementation Method 1
The light sensing circuit is used to sense the light intensity of the light emitting unit
Implementation Method 2
The charge storage unit is electrically connected to the comparator unit and stores an amount of electric charges
Data Source
AI summary
A light emitting device includes at least one light emitting unit, a switching unit, a comparator unit, a charge storage unit and a sensing unit. The switching unit is electrically connected to the light emitting unit. The comparator unit is electrically connected to the switching unit. The charge storage unit is electrically connected to the comparator unit and stores an amount of electric charges. The sensing unit has a light sensing circuit and is electrically connected to the charge storage unit. The light sensing circuit senses a light intensity of the light emitting unit. The sensing unit adjusts the amount of the electric charges and a voltage corresponding to the amount of the electric charges according to the light intensity. The comparator unit compares the voltage with a threshold voltage. The switching unit controls the light emitting unit in accordance with the result of the comparison.