Segmented LCD Backlight with Notch Light Barriers
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Solution Overview
Problem
Liquid crystal displays face limitations in achieving high dynamic contrast due to slow transition speeds of liquid crystal materials and light leakage between segments in segmented pulsing backlights, which compromises contrast ratios in time sequential stereoscopic displays.
Innovation Solution
A segmented backlight system with notches or cuts configured to reduce light leakage between non-adjacent segments, where each segment is illuminated by sets of LEDs with timing offsets optimized for individual rows of pixels, and notches can be variable in length, depth, and width, and even reflective or opaque to minimize light transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a segmented pulsing backlight is used in time sequential stereoscopic displays, then dynamic contrast is improved, but light leakage between segments occurs which compromises contrast ratios
Solution Approach 1:
The backlight is divided into multiple independently controllable segments that can be pulsed on and off separately. Each segment corresponds to specific rows of pixels and can be illuminated at different times, enabling time-sequential stereoscopic display with high dynamic contrast while preventing light leakage between segments through precise temporal control.
Solution Approach 2:
The backlight segments are pulsed periodically with optimized timing offsets for different segments. By alternating the illumination periods of adjacent segments and using variable pulse widths, the system achieves high dynamic contrast ratios while minimizing light leakage, as each segment is illuminated only during its designated time window.
2Illumination intensity
If notches or cuts are added to reduce light leakage, then contrast ratio is improved, but device complexity increases
Solution Approach 1:
The backlight structure is segmented into multiple independent units with notches or cuts between them. These physical divisions create natural light barriers that prevent lateral light leakage between adjacent segments, enhancing contrast ratio while maintaining a relatively simple overall structure that can be manufactured using standard PCB and LED mounting techniques.
Solution Approach 2:
Notches or cuts are strategically placed only at the boundaries between backlight segments where light leakage occurs, rather than throughout the entire structure. This localized modification effectively reduces light leakage and improves contrast ratio without significantly increasing overall device complexity or manufacturing difficulty.
3Illumination intensity
If variable timing offsets are applied to individual rows of pixels, then dynamic contrast is enhanced, but control complexity increases
Solution Approach 1:
The display is divided into multiple segments with independently controllable timing offsets. Each segment can be pulsed with optimized timing relative to adjacent segments, enabling enhanced dynamic contrast through simple on/off control of each segment without requiring complex per-pixel timing management.
Solution Approach 2:
Each backlight segment operates with a periodic pulse pattern and fixed timing offset relative to other segments. This periodic operation simplifies control complexity, as the timing relationships are predetermined and repeatable, eliminating the need for complex real-time timing adjustments while still achieving enhanced dynamic contrast.
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 approach enhances dynamic contrast by minimizing light leakage between segments, allowing for optimal timing of each segment to achieve higher contrast ratios across the entire display panel, improving performance in applications like low motion blur and low cross-talk in stereoscopic displays.
Implementation Method 1
one or more sets of light emitting diodes (LEDs) configured to illuminate the segmented backlight
Implementation Method 2
Each segment of the one or more segments may include one or more notches (or cuts) and each notch of the one or more notches may be configured as a light barrier that may reduce light leakage to non-adjacent segments
Data Source
AI summary
Systems and methods for increasing dynamic contrast in a liquid crystal display (LCD) may include a segmented backlight that may include one or more segments and one or more sets of light emitting diodes (LEDs). Each set of LEDs may be configured to illuminate a corresponding segment and each segment may include a notch(es) configured as a light barrier to reduce light leakage to non-adjacent segments. The notch(es) may be of variable length, depth, and width and may be three-dimensional, having a width the varies along the depth and length of the notch and a depth that varies along the width and length of the notch. In some embodiments, the notch(es) may be reflective, some degree of opaque, and/or blackened.