Backlight Unit Driver Power Controller for LCD Voltage Ripple
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Solution Overview
Problem
Prior art liquid crystal display backlight unit drivers do not forcibly disable the DC power source during unloaded conditions, leading to voltage ripple and noise generation due to abrupt load changes.
Innovation Solution
A liquid crystal display with a backlight unit driver that includes a power controller to enable or disable the DC power source based on signals from the driving transistors, using pulse width modulation to control the output and minimize voltage ripple.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the DC power source is not forcibly disabled during unloaded conditions, then the backlight unit can remain powered, but voltage ripple and noise are generated due to abrupt load changes
Solution Approach 1:
The patent applies dynamics by making the DC power source output controllable through a power controller that dynamically enables or disables the output based on the loading state of the backlight unit. The power controller monitors the drive signals from the transistor driver and adjusts the power source output accordingly, transforming the static power supply into a dynamic system that adapts to load conditions and prevents voltage ripple during unloaded states.
Solution Approach 2:
The patent implements feedback through the power controller that receives drive signals from the transistor driver and uses this information to control the DC power source output. The power controller creates a closed-loop system where the state of the backlight unit (through its drive signals) is fed back to control the power source, ensuring the power source is disabled when the backlight unit is unloaded and enabled when active, thereby eliminating voltage ripple and noise.
2Duration of action of stationary object
If the DC power source output is continuously enabled, then the backlight unit can operate without interruption, but voltage ripple occurs during load-off conditions
Solution Approach 1:
The power controller dynamically adjusts the DC power source output state based on real-time monitoring of the backlight unit's loading condition. When the backlight unit is in an unloaded state (load-off condition), the power controller disables the DC power source output, preventing voltage ripple. When the backlight unit is active, the power controller enables the output, ensuring continuous power supply. This dynamic control resolves the contradiction between continuity and ripple prevention.
Solution Approach 2:
The power controller operates periodically by monitoring the drive signals from the transistor driver and adjusting the power source output accordingly. The control action is synchronized with the backlight unit's operational state, enabling the power source during active periods and disabling it during idle periods. This periodic control ensures power continuity when needed while preventing voltage ripple during unloaded conditions.
3Object-generated harmful factors
If the DC power source is disabled during load-off condition, then voltage ripple is minimized, but the backlight unit cannot provide light when needed
Solution Approach 1:
The power controller continuously monitors the drive signals from the transistor driver, which reflect the operational state of the backlight unit. This feedback mechanism allows the power controller to distinguish between loaded and unloaded conditions accurately. When the backlight unit requires illumination, the drive signals indicate an active state, and the power controller accordingly enables the DC power source output. When the unit is unloaded, the power controller disables the output, minimizing voltage ripple. This feedback-based control ensures illumination is provided only when needed while preventing ripple during idle periods.
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 solution effectively minimizes voltage ripple and noise at the output terminal of the DC power source during load-off conditions by dynamically controlling the DC power source output based on the load state, thereby enhancing the stability of the liquid crystal display.
Implementation Method 1
a backlight unit providing light to the liquid crystal panel, and comprising light emitting sources having light emitting diodes connected in series
Data Source
AI summary
A liquid crystal display comprises: a liquid crystal panel; a panel driver for driving the liquid crystal panel; a backlight unit providing light to the liquid crystal panel, and comprising light emitting sources having light emitting diodes connected in series and driving transistors driving the light emitting sources; and a backlight unit driver comprising a transistor driver that controls the driving transistors, a DC power source that supplies DC power to the light emitting sources, and a power controller that drives the DC power source, and enables or disables an output of the DC power source with reference to signals supplied to the driving transistors.