Backlight Unit Flicker Reduction via Variable Driving Signals
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Solution Overview
Problem
Display devices face challenges in preventing flicker when operating in low-speed driving modes, leading to reduced luminance and increased power consumption, due to deviations in luminance among frames.
Innovation Solution
A backlight unit with a driver circuit that outputs variable light source driving signals in terms of frequency, duty, amplitude, or emission start timing, allowing for reduction of specific frequency components causing flicker during the one-frame period, thereby preventing visible flicker and optimizing power usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the display device is driven in a low-speed driving mode to reduce power consumption, then power consumption is reduced, but flicker occurs due to luminance deviations among frames
Solution Approach 1:
The patent applies periodic action by dividing the one-frame period into multiple subframe periods and applying different light source driving signals to each subframe. This creates a periodic modulation pattern that maintains average luminance while eliminating the harmful frequency components that cause flicker, thus allowing low-speed driving mode operation without visible flicker.
Solution Approach 2:
The patent implements dynamics by making the light source driving signals variable across different subframe periods. The driving signals are dynamically adjusted in terms of frequency, duty cycle, or amplitude for each subframe, enabling the system to adapt the backlight illumination pattern to eliminate flicker while maintaining power efficiency in low-speed driving mode.
2Use of energy by moving object
If the data retaining period is increased in low-speed mode, then power consumption is reduced, but luminance deviation among frames increases causing flicker
Solution Approach 1:
The patent applies segmentation by dividing the frame period into multiple subframe periods, each with its own light source driving signal. This segmentation allows independent control of illumination in each subframe, enabling the system to maintain stable average luminance across frames while reducing power consumption through the low-speed driving mode.
Solution Approach 2:
The patent implements parameter changes by varying the frequency, duty cycle, or amplitude parameters of the light source driving signals across different subframe periods. This parameter modulation enables the system to compensate for luminance deviations that would otherwise occur due to the extended data retaining period in low-speed mode, thereby maintaining luminance stability.
3Device complexity
If constant light source driving signals are used in low-speed mode, then device complexity is reduced, but flicker cannot be prevented
Solution Approach 1:
The patent applies periodic action by implementing a structured pattern of subframe periods with alternating or modulated light source driving signals. This periodic modulation provides a systematic approach to flicker prevention that, while more complex than constant signals, follows a predictable pattern that can be efficiently generated and controlled.
Solution Approach 2:
The patent implements dynamics by introducing variable light source driving signals that adapt to the low-speed driving mode requirements. The driver circuit is designed to generate these variable signals with different frequencies, duty cycles, or amplitudes for different subframes, providing the necessary complexity to prevent flicker while maintaining manageable device architecture.
Data Source
AI summary
A backlight unit and a display device are provided. The duty or the like of a light source driving signal is adjusted so that a frequency component causing flicker to be visible, among frequency components of luminance appearing in a driving period of low-speed driving mode. Flicker is prevented or reduced in the low-speed driving mode. The display device is driven in the low-speed driving mode to reduce power consumption. The display device is driven at a lower display driving frequency in the low-speed driving mode, thereby improving the efficiency thereof.