Backlight Unit DC-DC Converter Over-Current Control
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Solution Overview
Problem
The existing backlight units in display devices face over-current malfunctions due to significant voltage variations in DC-DC converters, leading to damage and reduced reliability.
Innovation Solution
A backlight unit with a DC-DC converter and a driving controller that adjusts the reference voltage and output voltage levels in response to an over-current control signal, ensuring the reference voltage increases before the output voltage when needed and decreases later than the output voltage, thereby preventing over-current phenomena.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the DC-DC converter converts low voltage to high voltage, then the backlight unit can operate at required voltage levels, but voltage stress increases causing over-current damage
Solution Approach 1:
The patent applies preliminary action by detecting over-current conditions before they cause damage and preemptively adjusting the driving pulse signal to prevent the harmful effect. The controller monitors the secondary voltage and reference voltage, and when over-current is detected, it adjusts the pulse signal in advance to prevent converter damage.
Solution Approach 2:
The patent implements feedback by continuously monitoring the secondary voltage from the DC-DC converter and comparing it with a reference voltage. The controller uses this feedback information to detect over-current conditions and adjust the driving pulse signal accordingly, creating a closed-loop control system that prevents converter damage.
2Measurement precision
If the reference voltage increases before the second voltage, then over-current detection accuracy improves, but control complexity increases
Solution Approach 1:
The patent applies preliminary action by setting the reference voltage to increase before the secondary voltage when over-current is detected. This timing arrangement allows the controller to prepare the reference voltage in advance, enabling accurate over-current detection at the moment it occurs without requiring complex real-time adjustment mechanisms.
Data Source
AI summary
A backlight unit includes a DC-DC converter that converts a first voltage to a second voltage in response to a driving pulse signal and a driving controller that outputs the driving pulse signal in response to an over-current control signal to control a reference voltage and a level of the second voltage. The driving controller controls the reference voltage in response to the over-current control signal such that the reference voltage increases prior to the second voltage by a predetermined time when the second voltage needs to be increased. In addition, the driving controller controls the reference voltage in response to the over-current control signal when the second voltage needs to be decreased such that the reference voltage decreases later than the second voltage by the predetermined time.