Backlight Unit Feedback Voltage Generator for Cost Reduction
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Solution Overview
Problem
The existing backlight units using light-emitting diodes (LEDs) face increased manufacturing and unit costs due to the need for controllers that can handle a wide permissible voltage range, as the feedback voltage required to adjust the driving voltage is equal to the difference between the driving voltage and the string voltage.
Innovation Solution
A backlight unit design that includes a feedback voltage generator to produce a first feedback voltage smaller than the difference between the driving voltage and the string voltage, allowing for a controller with a smaller permissible voltage range, comprising a driving-voltage supplier, an LED string, a feedback voltage generator, and a controller that adjusts the driving voltage based on this reduced feedback voltage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the feedback voltage is set equal to the difference between driving voltage and string voltage, then the driving voltage can be adjusted accurately, but the controller's permissible voltage range increases, leading to increased manufacturing and unit costs
Solution Approach 1:
The patent introduces a feedback voltage generator as an intermediary component that transforms the full-range feedback voltage (equal to driving voltage minus string voltage) into a reduced-range feedback voltage. This mediator allows the controller to operate with a smaller permissible voltage range while still enabling accurate driving voltage adjustment through the generated feedback signal.
2Adaptability or versatility
If the controller handles a wide permissible voltage range, then the driving voltage can be controlled across full range, but the manufacturing and unit costs increase
Solution Approach 1:
The feedback voltage generator acts as a mediator that enables full-range driving voltage control while protecting the controller from exposure to wide voltage ranges. By transforming the voltage information before it reaches the controller, the system maintains adaptability across the full driving voltage range while the controller itself only needs to handle a reduced, more cost-effective voltage range.
Solution Approach 2:
The patent changes the voltage parameter range that the controller needs to handle by introducing the feedback voltage generator. This component transforms the feedback voltage from a full-range signal (requiring expensive wide-range controllers) to a reduced-range signal (allowing use of cheaper narrow-range controllers), while maintaining the ability to control the full driving voltage range through parameter transformation.
Data Source
AI summary
A backlight unit, a method for driving the same, and a liquid crystal display device using the same are disclosed, in which a feedback voltage received in a controller to adjust a driving voltage to be supplied to a light-emitting diode string is smaller than a difference between the driving voltage and a string voltage, the backlight unit comprising a driving-voltage supplier; an LED string for receiving a driving voltage from the driving-voltage supplier, and generating a voltage drop corresponding to a string voltage; a feedback voltage generator for generating a first feedback voltage whose value is smaller than a difference between the driving voltage and the string voltage; and a controller for supplying a control signal to control the driving-voltage supplier based on the first feedback voltage.