Projector Polarization Conversion for Illuminance Uniformity
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Solution Overview
Problem
Projectors using laser light sources often experience illuminance unevenness due to incomplete depolarization in the light diffusing section, leading to reduced image quality as a result of intensity differences between P-polarized and S-polarized light.
Innovation Solution
A projector configuration that includes a solid-state light source emitting linearly polarized light, a birefringence element converting it into circularly or elliptically polarized light, a diffusion element, and a polarization conversion element that separates and converts the polarized light to reduce intensity unevenness, with an optical unit ensuring proper alignment and incidence angles for efficient polarization conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a light diffusing section is used to diffuse laser light, then the light is depolarized, but incomplete depolarization causes intensity unevenness between P-polarized and S-polarized light
Solution Approach 1:
A birefringence element is introduced as an intermediary component between the light source and the light diffusing section. This element converts linearly polarized light into circularly or elliptically polarized light, ensuring that when the light is subsequently diffused, the P-polarized and S-polarized components become equal in intensity, thereby eliminating illuminance unevenness while maintaining effective depolarization
Solution Approach 2:
The polarization state parameter of the light is changed from linear polarization to circular or elliptical polarization through the birefringence element. This parameter transformation ensures that the light, after passing through the light diffusing section, has equal proportions of P-polarized and S-polarized light, resolving the intensity unevenness issue
2Use of energy by moving object
If linearly polarized light is used as the light source, then the light source is efficient, but the light requires depolarization which may cause intensity unevenness
Solution Approach 1:
The birefringence element performs a preliminary action by converting the linearly polarized light from the efficient light source into circularly or elliptically polarized light before the light enters the diffusing section. This preliminary polarization transformation prevents the subsequent intensity unevenness that would otherwise occur during depolarization, allowing the system to maintain both high efficiency and uniform illumination
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 configuration ensures equal proportions of P-polarized and S-polarized light, reducing illuminance unevenness and enhancing image display quality by maintaining consistent light intensity across the projected area.
Implementation Method 1
a birefringence element that converts the linearly polarized light emitted from the solid-state light source into circularly or elliptically polarized light
Implementation Method 2
a diffusion element that diffuses the light having exited from the birefringence element
Implementation Method 3
a polarization conversion element that separates the diffused light having exited from the diffusion element into first polarized light polarized in a first polarization direction and second polarized light polarized in a second polarization direction
Data Source
AI summary
A projector includes a solid-state light source that emits linearly polarized light, a birefringence element that converts the linearly polarized light emitted from the solid-state light source into circularly or elliptically polarized light, a diffusion element that diffuses the light having exited from the birefringence element, and a polarization conversion element that separates the diffused light having exited from the diffusion element into first polarized light polarized in a first polarization direction and second polarized light polarized in a second polarization direction, converts the polarization direction of the first polarized light into the second polarization direction, and outputs the resultant first and second polarized light.