Chromatic Aberration Correction in Projection Light Collection
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Solution Overview
Problem
The existing light collecting optical systems for projection-type image displays face issues with longitudinal chromatic aberration, leading to reduced light utilization efficiency due to differences in refractive indices of glass materials for various wavelengths, which complicates the system and increases costs when using achromatic lenses.
Innovation Solution
The system arranges red, green, and blue surface-emitting light sources such that their optical distances to collimate lenses and a shared condenser lens are optimized to ensure secondary light source images of equal size, using dichroic mirrors for light synthesis and a single glass material for lenses to maintain a simple structure while correcting chromatic aberrations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the same structure and distance are used for collimate lenses of different colors, then the system structure is simplified, but longitudinal chromatic aberration increases causing different light collecting efficiencies for different colors
Solution Approach 1:
The patent applies local quality by making each collimate lens specific to its color (red, green, blue) with optimized parameters for that wavelength. Each lens has a focal length and position tailored to its specific color, allowing optimal light collection for each LED while minimizing chromatic aberration effects. This is evident in the claims which specify separate optical paths and lens parameters for each color.
Solution Approach 2:
The patent changes the parameters (focal length, position, curvature) of each collimate lens according to the wavelength of light it handles. By adjusting these parameters for each color, the system achieves optimal light collection efficiency for each wavelength while maintaining a relatively simple overall structure. The condenser lens also has optimized parameters for synthesizing the different colored light beams.
2Loss of energy
If achromatic lenses are used to correct chromatic aberration, then light collecting efficiency improves, but device complexity and product cost increase
Solution Approach 1:
Instead of using complex achromatic lenses, the patent segments the light collection system into separate monochromatic collimate lenses for each color (red, green, blue). Each lens is optimized for its specific wavelength, and the results are combined by a condenser lens. This segmentation approach achieves high light collection efficiency without requiring expensive and complex achromatic lenses, as each individual lens can be simpler and more specialized.
Solution Approach 2:
The condenser lens serves a universal function by receiving and synthesizing the collimated light beams from all three color lenses (red, green, blue) into a unified light path that enters the integrator rod. This single lens performs the multi-function of combining different wavelengths, eliminating the need for multiple specialized lenses and reducing overall system 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
This configuration achieves high light utilization efficiency without light quantity loss, enabling the display of high-brightness images with a simple and cost-effective optical system.
Implementation Method 1
a longitudinal chromatic aberration is generated due to a difference in characteristic that the shorter the wavelength is, the higher the refractive index of the glass material is
Implementation Method 2
the collimated light beams are synthesized by a dichroic mirror or the like
Data Source
Figure 1
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AI summary
A light collecting optical system (1) includes surface-emitting light sources (11r, 11g, 11b), collimate lenses (13r, 13g, 13b), and a condenser lens (19). Light emitting surfaces (12r, 12g, 12b) of the surface-emitting light sources have a rectangular shape of the same size as each other, and have a similar figure to an incident surface (21) of an integrator rod (20), the collimate lenses (13r, 13g, 13b) are disposed so that the optical distances from the collimate lenses (13r, 13g, 13b) to the condenser lens (19) are approximately the same, and the surface-emitting light sources are disposed so that the optical distances Lr, Lg and Lb from the light emitting surfaces (12r, 12g, 12b) to the collimate lenses (13r, 13g, 13b) satisfy Lb < Lg < Lr and so that images of the light emitting surfaces, which are formed on the incident surface (21) of the integrator rod (20) by the collimate lenses (13r, 13g, 13b) and the condenser lens (19), have approximately the same size.