Backlight Drive Normalization for Luminance Stability
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Solution Overview
Problem
Existing liquid crystal display devices face challenges in stabilizing backlight luminance due to individual differences in LEDs and varying operating conditions, leading to overshooting and increased time to reach target luminance, as current feedback control methods struggle with balancing speed and accuracy.
Innovation Solution
A driving device and method that include a drive normalization part, low-pass filter, and BL-drive value calculation part to estimate and smooth light quantity measurements, allowing for precise adjustment of BL-drive values to match target luminance, thereby stabilizing backlight output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a low-pass filter is used to eliminate noise from light quantity measurement, then measurement stability is improved, but feedback speed is reduced causing increased time to reach target luminance
Solution Approach 1:
The patent applies preliminary action by calculating a normalized light quantity measurement that compensates for the BL-drive value before feeding it to the low-pass filter. This normalization process (Equation 1: Lsn = Lmn × dp/dn) prepares the measurement data in advance to reflect what the light quantity would be at a reference drive level, allowing the low-pass filter to work with pre-processed data that requires less smoothing and thus maintains faster feedback speed while still achieving measurement stability.
2Stability of the object's composition
If feedback control speed is reduced to suppress overshooting, then luminance stability is improved, but the time to reach newly-set luminance is increased
Solution Approach 1:
The patent implements feedback by continuously monitoring the actual light quantity measurement and comparing it with the normalized reference value. The BL-drive value calculation part uses this feedback loop to dynamically adjust the BL-drive value, applying correction amounts based on the difference between measured and expected light quantities. This active feedback mechanism maintains luminance stability by correcting deviations in real-time without requiring slow feedback control speeds.
Solution Approach 2:
The patent applies parameter changes by dynamically adjusting the BL-drive value based on the normalized light quantity measurement. The system changes the drive parameter (BL-drive value) in response to variations in light quantity, allowing it to adapt to individual LED differences and temperature changes. This dynamic parameter adjustment enables the system to maintain stable luminance while responding quickly to user settings changes.
3Device complexity
If individual LED differences and temperature variations are not compensated, then device complexity is reduced, but luminance control accuracy is worsened
Solution Approach 1:
The patent applies self-service by enabling the backlight system to automatically compensate for its own variations using an optical sensor and normalization calculation. The system measures its own light output and adjusts the BL-drive value based on the normalized measurement, making the system self-regulating. This self-service approach improves luminance control accuracy without requiring external calibration equipment or complex manual adjustment mechanisms.
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 reduces the time to adjust backlight luminance to a user's preferred setting while preventing overshooting, ensuring stable and accurate luminance control across varying conditions.
Implementation Method 1
an optical sensor which is able to measure the light quantity of received light
Data Source
AI summary
A driving device includes a drive normalization part configured to calculate a reference light quantity measurement which is estimated when a backlight is driven using the predetermined reference BL-drive value based on a current BL-drive value and a light quantity measurement of the backlight; a low-pass filter configured to calculate a moving average among a plurality of reference light quantity measurements being temporarily held, thus outputting the smoothed reference light quantity measurement precluding noise; and a BL-drive value calculation part configured to calculate a target BL-drive value which allows the smoothed reference light quantity measurement to match the target light quantity corresponding to a user's setting of luminance.