Optical Compensation Apparatus for VA Liquid-Crystal Panels
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Solution Overview
Problem
Existing liquid-crystal projector apparatuses using VA-type panels face challenges in achieving high contrast due to pretilt-induced phase deviations, which are difficult to compensate effectively with existing optical compensation methods, particularly for oblique light components.
Innovation Solution
An optical compensation apparatus comprising a negative C-plate and two O-plates, where the composite phase difference in the tilt-direction cross section matches the phase difference produced by oblique light in the liquid-crystal panel, with a specific inclination coefficient to suit varying pretilt angles, allowing for effective phase deviation offset.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single O-plate is used for phase deviation compensation, then the structure is simple, but the N1 axis inclination cannot be freely set to match the pretilt angle of liquid crystal
Solution Approach 1:
The single O-plate is divided into two separate O-plates (first O-plate and second O-plate). Each O-plate can have its N1 axis independently oriented, allowing the first O-plate's N1 axis to be set at a first inclination and the second O-plate's N1 axis to be set at a second inclination. This segmentation enables flexible adaptation to different pretilt angles while maintaining structural simplicity.
2Ease of manufacture
If the N1 axis inclination is set to 45-60 degrees for vapor deposition, then the manufacturing is feasible, but it does not suit the pretilt angle of several degrees in liquid crystal panel
Solution Approach 1:
The inclination parameters of the N1 axes are changed from the conventional 45-60 degrees to smaller angles (first inclination and second inclination) that match the liquid crystal pretilt angle of several degrees. This parameter change enables both manufacturing feasibility and precise matching of the pretilt angle.
3Device complexity
If a single O-plate with two-axial refractive-index oval is used, then the structure is simple, but it cannot suitably compensate for one-axial liquid crystal phase deviation
Solution Approach 1:
The single two-axial O-plate is segmented into two separate O-plates. The first O-plate and second O-plate can be designed with appropriate refractive-index oval characteristics to match the one-axial liquid crystal phase deviation more effectively, improving compensation reliability while keeping the overall structure relatively simple.
4Device complexity
If conventional optical compensation methods are used, then the system is simple, but oblique light phase deviation cannot be effectively compensated
Solution Approach 1:
The conventional optical compensation parameters are changed by introducing two O-plates with specific inclination coefficients. The first inclination coefficient and second inclination coefficient are optimized to effectively compensate for oblique light phase deviation, improving compensation effectiveness while maintaining system simplicity.
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 configuration improves contrast by suitably offsetting phase differences produced by oblique light, accommodating a wide range of pretilt angles and reducing the need for separate compensation plates, thereby minimizing system complexity and cost.
Implementation Method 1
an amount of a composite phase difference between the two O-plates and the negative C-plate in a tilt-direction cross section is substantially same as an amount of a phase difference produced by light having each of incident angles
Implementation Method 2
the O-plate is an optical medium in which an N1 axis having the highest refractive index tilts with respect to a thickness direction when the O-plate is shown by a refractive-index oval
Implementation Method 3
negative C-plate (medium having a low refractive index in thickness direction)
Data Source
AI summary
An improvement in contrast is achieved by suitably offsetting a phase difference produced by oblique light in a liquid-crystal panel.An optical compensation apparatus includes a negative C-plate and two O-plates, an amount of a composite phase difference between the two O-plates and the negative C-plate in a tilt-direction cross section is substantially same as an amount of a phase difference produced by light having each of incident angles in a predetermined incident-angle range in the liquid-crystal panel, and a sign of the composite phase difference is opposite to a sign of the phase difference, the tilt-direction cross section being a cross section parallel to a tilt direction of the liquid crystal in a vertical-alignment-type liquid-crystal panel.