Projection Display Light Recycling Polarization Transformation
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Solution Overview
Problem
Conventional projection display devices have low light utilization efficiency, resulting in poor image quality due to the wastage of transmitted parallel polarized light, with previous attempts to improve this efficiency only partially successful.
Innovation Solution
A projection display device incorporating a light recycling system that transforms and reversely transmits polarized light, utilizing a PBS to transmit one type and reflect another, and includes a light recycling device with components like reflectors and quarter-wave plates to enhance light usage, potentially using right-angle prisms and half-wave plates to achieve improved efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional projection display device uses only reflected parallel polarized light from the PBS to project image, then the structure is simple, but the light utilization efficiency is low (less than 10%)
Solution Approach 1:
The patent recovers the transmitted parallel polarized light that would normally be discarded by the PBS. The light recycling device captures this transmitted light, transforms its polarization state using wave plates, and redirects it back through the PBS to be reflected toward the display panel, thereby recovering useful light energy that would otherwise be wasted.
Solution Approach 2:
The patent creates a continuous cycle where light is repeatedly utilized. The light recycling device ensures that both reflected and transmitted parallel polarized light are continuously converted and directed toward the display panel, maintaining continuous useful action on the light rather than allowing it to be lost after single use.
2Manufacturing precision
If aspherical lenses and cylinder lenses are used to adjust the light beam, then the light spot matching the LCOS shape is improved, but the light utilization efficiency is still low due to single-polarized-light usage
Solution Approach 1:
The patent makes the optical system universal by enabling it to handle both reflected and transmitted parallel polarized light effectively. The light recycling device with wave plates provides multi-functionality in converting polarization states, allowing the system to utilize both types of polarized light for image projection rather than being limited to one type.
3Loss of energy
If a light recycling device is added to transform and reversely transmit polarized light, then the light utilization efficiency is significantly improved, but the device complexity increases
Solution Approach 1:
The patent introduces wave plates as intermediary elements between the PBS and the display panel. These wave plates act as mediators that transform the polarization state of light, enabling the light recycling device to convert transmitted parallel polarized light into a form that can be effectively utilized by the display panel.
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 light recycling system significantly enhances light utilization efficiency, strengthening image quality and enabling three-dimensional display by combining left-eye and right-eye images.
Implementation Method 1
The PBS 12 forms an angle with respect to the first direction (x-axis), and transmits one of the two types of parallel polarized light and reflects the other. For example, the PBS 12 transmits the p-polarized light (polarized direction is parallel to the rays incident plane) and reflects the s-polarized light (polarized direction is vertical to the rays incident plane).
Implementation Method 2
The s- or p-polarized light are defined relative to the plane of incidence of the ray on the surface, which are not characteristics of the beam itself but just two types of parallel polarized light out of PBS in this invention. The s-polarized light is incident into the surface of the display panel 13, and is transformed to p-polarized light by the LCOS for being reflected back to the PBS 12.
Implementation Method 3
The light recycling device includes light recycling components and a second display panel. The light recycling components are adapted to transform the first type parallel polarized light transmitted by the PBS to the second type parallel polarized light.
Data Source
AI summary
A projection display device includes a first display panel (23a), a second display panel (23b), a PBS (Polarization Beam Splitter) (22) with a first surface (22a) and a second surface (22b) opposite each other, a light recycling device (25a, 25b and 23b), and a projection lens (24). The PBS (22) transmits a first type parallel polarized light and reflects a second type parallel polarized light. The light recycling device (25a, 25b and 23b) transforms the first type parallel polarized light transmitted by the PBS (22) into the second type parallel polarized light which carries a second image information, then reversely transmits the second type parallel polarized light to the second surface (22b) of the PBS (22). The projection display device improves the light utilization efficiency and can be used for 3D display.