LED Backlight Driving Circuit Using Latch Unit to Reduce Transmission Lines
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Solution Overview
Problem
Conventional LED backlight modules for LCDs face issues with increased transmission lines and time, inflexible control methods, and higher fabrication costs due to the use of pulse width modulation (PWM) and division controlling.
Innovation Solution
A driving circuit and method that incorporates a latch unit and a switch unit to receive and process control backlight data with a trigger signal during a frame period, reducing transmission lines and time, and using fixed-voltage control to decrease fabrication costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If PWM and division controlling are used to control LED backlight modules, then the control precision and brightness uniformity are improved, but the transmission lines and transmission time are substantially increased
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the duty cycle values in a lookup table before actual backlight control is needed. The conversion from grayscale values to PWM duty cycles is performed in advance, so that during frame rendering, only simple table lookup and signal generation are required, eliminating complex real-time calculations and reducing transmission time.
Solution Approach 2:
The patent divides the backlight control into preliminary steps: (1) pre-converting grayscale values to duty cycles and storing in lookup tables, (2) pre-dividing the screen into control regions, and (3) pre-configuring the control logic. This preliminary preparation allows the actual control process to use simple, fast operations, thereby improving control precision without increasing transmission time.
2Measurement precision
If PWM and division controlling are used to control LED backlight modules, then the control precision and brightness uniformity are improved, but the fabrication cost is substantially increased
Solution Approach 1:
The patent merges the backlight control function into the existing display controller by adding a control unit that integrates with the display controller's existing resources (lookup tables, timing control, signal generation). This integration eliminates the need for separate, expensive current controller circuits in each control region, thereby improving control precision while reducing fabrication cost.
Solution Approach 2:
The patent makes the display controller multi-functional by enabling it to perform both display signal processing and backlight control functions. The control unit within the display controller can generate PWM signals, manage lookup tables, and control multiple backlight regions, replacing what would traditionally require dedicated current controllers. This universality reduces component count and fabrication cost while maintaining precise control.
3Illumination intensity
If division controlling with multiple control regions is implemented, then the brightness uniformity and local dimming performance are improved, but the device complexity is substantially increased
Solution Approach 1:
The patent merges multiple control regions and their control logic into a single integrated control unit within the display controller. Instead of having separate control circuits for each region, the unified control unit manages all backlight regions using shared resources (lookup tables, timing control, signal generation pathways), thereby achieving good brightness uniformity across regions while minimizing device complexity.
Solution Approach 2:
The control unit is designed as a multi-functional component that can simultaneously or independently control multiple backlight regions. It uses universal control mechanisms (PWM generation, duty cycle adjustment, timing control) that work across all regions, eliminating the need for region-specific control circuits and reducing overall device complexity while maintaining brightness uniformity.
Data Source
AI summary
A light emitting diode (LED) backlight module, a driving apparatus and a driving method thereof are provided. The driving apparatus is adapted to drive at least one LED of at least one lighting unit within the LED backlight module. The driving apparatus includes a latch unit and a switch unit. The latch unit is used for receiving a control backlight data and latching the control backlight data during a frame period according to a trigger signal, so as to output a control signal. The switch unit is coupled to the latch unit and the LED for receiving the control signal to determine whether the LED emits or not.