Backlight Control for Liquid Crystal Display Image Quality
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Solution Overview
Problem
Conventional liquid crystal display apparatuses face issues with image quality due to inadequate display of dark portions when controlling backlight luminance based on maximum luminance values, leading to deterioration where black appears white.
Innovation Solution
An image display apparatus that includes a backlight, a liquid crystal panel, an emission intensity calculating unit, a backlight controlling unit, a signal correcting unit, and a liquid crystal controlling unit, which calculates and adjusts the emission intensity to ensure the center value of the lightness range matches the center value between maximum and minimum lightness of the input image, thereby correcting signal luminance and modulating the liquid crystal panel for improved image display.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the backlight luminance is controlled based on the maximum luminance value in the input image, then the maximum luminance can be displayed, but the dark portion of the input image is not sufficiently displayed and black appears white
Solution Approach 1:
The invention changes the control parameter from maximum luminance value to average luminance value of the input image. By calculating the average luminance and using it to control the backlight emission intensity, the system achieves balanced display across the entire luminance range, preventing both overexposure of dark areas and loss of detail in bright areas.
Solution Approach 2:
The system implements a feedback mechanism where the luminance characteristics of the input image are analyzed and used to adjust the backlight emission intensity. The average luminance value serves as feedback information that dynamically controls the backlight to optimize the display of both dark and bright portions of the image.
2Illumination intensity
If the emission intensity of the backlight is increased to display bright portions, then the bright portion can be displayed, but the dark portion becomes insufficient and image quality deteriorates
Solution Approach 1:
The invention changes the control parameter from maximum luminance to average luminance, which inherently balances the emission intensity to preserve information across the full luminance spectrum. This parameter change ensures that dark portion information is not lost while still displaying bright portions adequately.
3Use of energy by moving object
If the backlight emission intensity is dynamically adjusted, then power consumption can be reduced, but image quality may deteriorate if not controlled properly
Solution Approach 1:
The invention uses average luminance as the control parameter for dynamic backlight adjustment, which optimizes power consumption while maintaining image quality. This approach reduces power consumption compared to maximum luminance control, while the average luminance-based control prevents image quality deterioration by ensuring balanced display across all luminance ranges.
Solution Approach 2:
The feedback mechanism using average luminance information dynamically adjusts backlight emission to match the actual content requirements, reducing power consumption when the image contains predominantly dark areas while maintaining proper display quality across varying image content.
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
This solution minimizes lightness differences in the displayed image, reducing subjective image deterioration and enabling a wider dynamic range with lower power consumption by ensuring accurate representation of both bright and dark portions.
Implementation Method 1
The liquid crystal panel modulates light emitted from the backlight
Data Source
AI summary
An image display apparatus for displaying images based on signals of an input image is provided. A backlight emits light. A liquid crystal panel modulates light emitted from the backlight. A emission intensity calculating unit calculates an emission intensity of the backlight such that a center value of a lightness range displayable on the panel defined depending on the emission intensity of the backlight substantially agrees with a center value between maximum and minimum values of lightness of each signal of the input image. A backlight controlling unit controls light emission of the backlight such that the light is emitted with the emission intensity. A signal correcting unit corrects each signal of the input image in accordance with the emission intensity. A liquid crystal controlling unit controls modulation of the liquid crystal panel based upon the corrected signals.