Polarization Converting Element for Projection Display Uniformity
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Solution Overview
Problem
Current projection display devices experience non-uniform intensity distribution due to changes in polarization state as light passes through or is reflected by optical systems, leading to decreased light use efficiency and impaired luminance.
Innovation Solution
Incorporating a polarization converting element that converts the polarization direction of modulated light to radially extend from the center of the optical axis, ensuring uniform intensity distribution and enhanced light use efficiency by aligning polarization directions with the optical system's axis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If linearly polarized light is incident onto a lens group or concave mirror, then the light can be transmitted or reflected, but the intensity distribution becomes non-uniform due to polarization-dependent transmittance or reflectance
Solution Approach 1:
The patent changes the polarization state parameter from linear to circular polarization by inserting a quarter-wave plate. This parameter change makes the light interaction with optical surfaces independent of orientation, thereby achieving uniform intensity distribution while maintaining high light use efficiency. The quarter-wave plate converts the polarization state such that the light is no longer subject to polarization-dependent transmittance or reflectance variations.
2Illumination intensity
If a quarter wavelength plate is arranged to convert light to circularly polarized state, then the intensity distribution becomes uniform, but the light transmittance and reflectance are decreased
Solution Approach 1:
The patent changes the polarization state parameter from linear to circular polarization by inserting a quarter-wave plate. This parameter change makes the light interaction with optical surfaces independent of orientation, thereby achieving uniform intensity distribution while maintaining high light use efficiency. The quarter-wave plate converts the polarization state such that the light is no longer subject to polarization-dependent transmittance or reflectance variations.
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 solution achieves uniform brightness projection by maintaining consistent light transmittance and reflectance across the projection plane, enhancing light use efficiency and luminance performance.
Implementation Method 1
a first polarization converting portion, arranged between the imager and the projecting optical system, for converting a polarization direction of the modulated light into a direction radially extending from a center of an optical axis of the projecting optical system
Data Source
AI summary
In a projection display device, a polarization converting element is provided between an imager and a refracting optical system for converting a polarization direction of light after modulation into a direction radially extending from the center of the optical axis of the refracting optical system. Light transmitted through the polarization converting element is incident onto the refracting optical system in a state of P-polarized light or a state close to the state of P-polarized light. Thereby, the transmittance of light through the refracting optical system is made substantially uniform and increased.