Dual Liquid Crystal Polarization Modulator for 3D Projection
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Solution Overview
Problem
Existing polarization modulators for time-multiplexed stereoscopic 3D applications face challenges with slow transition times between polarization states, particularly in unpowered transitions, which lead to image crosstalk and brightness loss, especially in modern 3D systems requiring rapid switching.
Innovation Solution
The use of two liquid crystal devices in optical series, where one device compensates the change made by the other, allowing for dynamic offset of polarization states through controlled drive signals, enabling fast and powered transitions while hiding the slower unpowered transitions, thus maintaining the initial polarization state during relaxation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a single liquid crystal device is used as a polarization switch, then the device structure is simple, but the transition time between polarization states is too slow for modern 3D applications
Solution Approach 1:
The single liquid crystal device is divided into two separate liquid crystal devices operating in push-pull mode. One device handles the powered transition while the other handles the unpowered transition, allowing each to operate optimally without compromising the other. This segmentation resolves the contradiction by enabling fast transitions through distributed functionality across multiple devices.
Solution Approach 2:
Two liquid crystal devices are combined in a push-pull configuration where their transitions are coordinated. The powered transition of one device compensates for the unpowered transition of the other, effectively merging their capabilities to achieve fast overall transition times while maintaining structural simplicity through symmetric design.
2Use of energy by moving object
If unpowered transitions are used in polarization switching, then energy consumption is reduced, but image crosstalk and brightness loss occur due to slow transition speed
Solution Approach 1:
The system employs periodic alternating transitions where powered and unpowered transitions are applied in sequence to different liquid crystal devices. This periodic action ensures that when one device undergoes a slow unpowered transition, the other device simultaneously undergoes a fast powered transition, maintaining overall system performance and preventing image crosstalk while keeping energy consumption low.
Solution Approach 2:
The push-pull configuration ensures continuous useful action by having one device always ready to compensate for the other during transition. The coordinated switching maintains uninterrupted polarization control, preventing image quality degradation while allowing energy-efficient unpowered transitions to occur periodically.
3Speed
If fast powered transitions are applied to both liquid crystal devices simultaneously, then switching speed is maximized, but power consumption increases significantly
Solution Approach 1:
The system dynamically alternates which liquid crystal device undergoes a powered transition and which undergoes an unpowered transition. This dynamic switching strategy ensures that fast switching speed is maintained through coordinated powered transitions while power consumption is reduced by allowing periodic unpowered transitions, resolving the contradiction between speed and energy use.
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 enables rapid switching between polarization states without introducing image crosstalk or brightness loss, suitable for modern time-multiplexed stereoscopic 3D applications, even in battery-operated devices, by utilizing powered transitions for quick switching and leveraging the slower unpowered transitions to maintain polarization state during image updates.
Implementation Method 1
The liquid crystal material itself is birefringent and the optic axis direction of this birefringent material can be controlled with an applied voltage
Implementation Method 2
This has the effect of rotating linearly polarized incoming light by 90° through a 'waveguiding' principle
Implementation Method 3
Upon application of a voltage to the liquid crystal device, the liquid crystal directors align perpendicular to the substrate, with the result that the twisted liquid crystal director structure disappears
Data Source
AI summary
An optical polarization state modulator assembly for use in a stereoscopic three-dimensional image projection system includes a spatial light modulator, a light source emitting multiple wavelength components of light for incidence on the spatial light modulator, and a projection lens. A polarization converter system cooperates with the spatial light modulator to produce in alternating sequence polarized light carrying first and second perspective view images of a scene in different ones of first and second subframes. A polarization modulator, in response to first and second drive signals, imparts to, respectively, the image-carrying polarized light a first output polarization state during the first subframe and to the image-carrying polarized light a second output polarization state during the second subframe. The image-carrying polarized light in the first and second output polarization states propagates through the projection lens for transmission to an observer.