Backlight Driving Apparatus Switching Controller Efficiency
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Solution Overview
Problem
Conventional backlight driving apparatuses experience power loss and reduced power conversion efficiency due to switching losses and varying load conditions caused by repeated on/off cycles of LED arrays, making it difficult to maintain a constant power conversion efficiency.
Innovation Solution
Incorporating a switching controller that generates a pulse width modulation (PWM) signal to control the switching element's turn-on/off based on feedback voltage and LED duty signals, allowing for selective control of the switching element during duty-off sections and maintaining constant power conversion efficiency by using a burst mode or normal mode depending on the duty-on section duration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the switching element is turned on continuously to maintain voltage regulation, then the DC-DC converter can maintain stable operation, but switching losses occur during duty-off sections reducing power conversion efficiency
Solution Approach 1:
The patent applies dynamics by making the switching element's operation state variable rather than fixed. The switching controller dynamically adjusts the switching element's on/off state based on real-time detection of LED array operation state and feedback voltage, allowing the system to adapt between continuous switching (for stability) and intermittent switching (for efficiency) modes.
Solution Approach 2:
The patent changes the operational parameter of the switching element from continuous on-state to controlled intermittent on-state. By modifying the switching frequency and duty cycle parameters based on LED array operation state, the system maintains stable voltage regulation while minimizing switching losses during duty-off sections.
2Ease of operation
If the LED arrays are repeatedly turned on/off to adjust brightness, then backlight dimming control is achieved, but load conditions vary making it difficult to maintain constant power conversion efficiency
Solution Approach 1:
The patent implements feedback by using a feedback circuit to continuously monitor the voltage level output by the DC-DC converter and feed this information back to the switching controller. This feedback mechanism allows the controller to detect changes in load conditions caused by LED on/off cycles and adjust switching parameters accordingly, maintaining constant power conversion efficiency despite brightness adjustments.
Solution Approach 2:
The system dynamically adapts the switching element's operation to match the varying load conditions created by LED arrays being turned on and off for dimming control. The switching controller adjusts switching frequency and duty cycle in real-time based on detected LED operation state, ensuring optimal power conversion efficiency across different brightness levels.
3Speed
If the switching element operates at high frequency for rapid response, then the DC-DC converter responds quickly to voltage changes, but switching losses increase reducing overall efficiency
Solution Approach 1:
The patent applies dynamics by making the switching frequency variable rather than fixed. The switching controller adjusts the switching frequency dynamically based on the detected operation state of the LED arrays and feedback voltage levels, allowing high frequency operation when needed for rapid response and lower frequency operation to minimize switching losses during steady-state conditions.
Data Source
AI summary
Disclosed is a backlight driving apparatus. The backlight driving apparatus includes a light source configured to include at least one LED, a DC-DC converter configured to generate a driving voltage according to a turn-on of a switching element and supply the driving voltage to the light source, a feedback circuit configured to generate a feedback voltage corresponding to a voltage level of the driving voltage supplied from light source, a duty controller connected to the light source, and configured to control a turn-on period of the LED according to an LED duty signal corresponding to a backlight dimming signal, and a switching controller configured to generate a PWM signal for controlling the turn-on of the switching element according to the feedback signal, generate a switching control signal corresponding to the PWM signal according to the LED duty signal, and selectively control the turn-on of the switching element.