Backlight Driving Circuit Adjustable Load OCP Threshold
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Solution Overview
Problem
Backlight driving circuits in LCDs face damage and reduced lifespan due to excessive output power in 3D display mode, as existing constant current driver chips lack multiple over current protection (OCP) threshold values, leading to inadequate protection in both 2D and 3D modes.
Innovation Solution
A backlight driving circuit with an adjustable load and a constant current driver chip, featuring a switching module that adjusts resistance values based on display mode, allowing for multiple OCP threshold values without altering the internal chip structure, using connected-in-parallel resistors and controllable switches to manage current and voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single OCP threshold value is set according to 2D display mode, then the circuit protection is sufficient for 2D mode, but the output power becomes too high in 3D mode causing circuit component damage
Solution Approach 1:
The patent applies dynamics by making the load resistance adjustable based on display mode. The load resistance is dynamically changed between a first resistance value (for 2D mode) and a second resistance value (for 3D mode) through switching modules controlled by mode signals, allowing the OCP threshold to adapt to different operating conditions and prevent excessive power in 3D mode while maintaining adequate protection in 2D mode
Solution Approach 2:
The patent changes the resistance parameter of the load according to display mode. By switching between different resistance values (first resistance value for 2D, second resistance value for 3D), the OCP threshold is adjusted to match the power output characteristics of each mode, resolving the contradiction between sufficient protection in 2D mode and preventing excessive power in 3D mode
2Device complexity
If the OCP threshold is not adjusted for different display modes, then the circuit structure remains simple, but the working life of the backlight driving circuit is reduced due to component damage from excessive power
Solution Approach 1:
The patent introduces dynamic adjustment of load resistance through switching modules that are controlled by display mode signals. This dynamic configuration allows the circuit to adapt its OCP threshold to match the power output of different display modes, protecting components from damage and extending working life while maintaining relatively simple circuit architecture through the use of standard switching components
3Reliability
If multiple OCP threshold values are implemented, then the protection is adequate for both 2D and 3D modes, but the circuit complexity increases
Solution Approach 1:
The patent segments the load into multiple resistive elements (first load resistance and second load resistance) that can be independently switched. Each segment corresponds to a specific display mode, allowing the circuit to select the appropriate resistance value based on the active mode. This segmentation enables multiple OCP thresholds without requiring complete redesign of the circuit architecture
Solution Approach 2:
The switching modules serve multiple functions: they adjust the load resistance for different display modes and simultaneously control the OCP threshold. This multi-functionality reduces overall circuit complexity by combining mode selection and protection threshold adjustment into a single control mechanism, achieving adequate protection for both 2D and 3D modes without proportionally increasing circuit complexity
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 protects the backlight driving circuit by adjusting resistance values for different display modes, ensuring appropriate current levels and reducing material costs, thereby extending the circuit's lifespan and simplifying circuit control.
Implementation Method 1
when a current flows through the resistors, a voltage difference is formed at two end of the resistors then the voltage difference is fed back to the constant current driver chip
Data Source
AI summary
A backlight driving circuit includes a power module and a constant current driver chip. The power module includes a first controllable switch. An adjustable load is connected between the first controllable switch and a ground terminal of the backlight driving circuit, and the adjustable load includes a switching module controlling a resistance value of the adjustable load, a switching mode signal of the backlight driving circuit is sent to a control end of the switching module. A first end of the adjustable load that is connected to the first controllable switch is coupled to an over current protection (OCP) port of the constant current driver chip.