Two-Lens Projector Group for Uniform Beam Illumination
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Solution Overview
Problem
Single-panel projectors face issues with dark peripheral portions in projection images due to elliptical beam distribution caused by varying transmittance of light through single lenses, leading to non-uniform brightness and size challenges.
Innovation Solution
A projector design featuring a lens group with two convex lenses, a light-incident-side polarizer, a light modulator with sub-pixels for different colors, and a light-exiting-side polarizer, which reduces the angle of incidence and maintains a circular beam distribution, thereby minimizing dark peripheries and enhancing image uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single lens is used in the light collecting system, then the device complexity is reduced, but the beam distribution becomes elliptical causing dark peripheral portions in the projection image
Solution Approach 1:
The single lens is divided into two separate lenses: a first lens and a second lens. The first lens has a first focal length and the second lens has a second focal length, creating a lens group that processes the beam in two stages. This segmentation allows each lens to be optimized independently, with the first lens controlling overall beam parameters and the second lens specifically correcting peripheral illumination to eliminate dark areas.
Solution Approach 2:
The patent introduces different focal lengths for the two lenses (first focal length and second focal length) to change the optical parameters of the beam path. By adjusting these focal length parameters, the system transforms the elliptical beam distribution into a circular distribution, ensuring uniform illumination across the liquid crystal panel while maintaining device feasibility.
2Illumination intensity
If the lens power is increased to correct beam distribution, then the beam uniformity improves, but the angle of incidence increases causing varying transmittance and elliptical beam shape
Solution Approach 1:
The optical correction function is segmented between two lenses rather than concentrated in one high-power lens. The first lens performs initial beam shaping, and the second lens completes the correction with lower power. This distribution reduces the angle of incidence at each interface, preventing the beam shape distortion that would occur with a single high-power lens.
Solution Approach 2:
The first lens acts as an intermediary element between the light source and the second lens. It pre-shapes the beam and reduces the angle of incidence before the beam reaches the second lens. This intermediary role allows the second lens to perform the final correction without experiencing excessive angles of incidence, maintaining beam shape consistency.
3Illumination intensity
If a lens group with two lenses is used, then the beam distribution becomes circular improving image uniformity, but the device complexity increases
Solution Approach 1:
The first lens and second lens are combined into a single lens group assembly that functions as one integrated optical unit. Although two separate lenses are used, they are positioned and oriented to work together as a cohesive system, achieving circular beam distribution and uniform illumination while managing the overall complexity through coordinated design.
Solution Approach 2:
By specifying different focal lengths for the two lenses (first focal length and second focal length), the system uses parameter optimization to achieve the desired beam shape. This parameter-based approach allows the complex two-lens system to be designed and manufactured efficiently, balancing the improvement in image uniformity with acceptable device complexity.
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 design achieves a circular beam distribution, reducing dark peripheral issues and allowing for uniform brightness in projected images, while also enabling a more compact and cost-effective projector structure.
Implementation Method 1
a lens group that parallelizes a beam output from the light source... The lens group includes two lenses each having positive power
Implementation Method 2
a light-incident-side polarizer that transmits the beam that exits out of the lens group
Implementation Method 3
a light modulator that modulates the beam passing through the light-incident-side polarizer to form a projection image
Implementation Method 4
a light-exiting-side polarizer that transmits the beam modulated by the light modulator
Data Source
AI summary
A projector includes a light source, a lens group that parallelizes the beam output from the light source, a light-incident-side polarizer that transmits the beam having exited out of the lens group, a light modulator that modulates the beam having passed through the light-incident-side polarizer to form a projection image, a light-exiting-side polarizer that transmits the beam modulated by the light modulator, and a projection lens that projects the beam having passed through the light-exiting-side polarizer. The light modulator includes first sub-pixels on which blue light is incident, second sub-pixels on which green light is incident, and third sub-pixels on which red light is incident. The lens group includes two lenses each having positive power. The two lenses each have a convex surface.