Projection Apparatus Illumination Angle Optimization
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Solution Overview
Problem
Existing projection apparatuses using micromirror elements face challenges in achieving brighter images while maintaining uniform left-right brightness, leading to potential image quality deterioration due to beam overlap and asymmetry.
Innovation Solution
A projection apparatus is designed with an illumination optical system that adjusts the incidence angle of the illumination light to (2A+α)° from a direction less than 45° relative to the micromirror array surface, allowing the micromirrors to tilt ±A° and project a brighter image with balanced left-right brightness by preventing beam overlap and asymmetry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the incidence angle of illumination light is increased to improve image brightness, then the projected image becomes brighter, but beam overlap occurs causing asymmetric brightness distribution
Solution Approach 1:
The patent applies asymmetry by deliberately setting the illumination optical axis at a specific asymmetric angle (2A+α) relative to the micromirror array normal. This asymmetric configuration prevents beam overlap between the illumination path and projection path, thereby maintaining uniform brightness distribution across the projected image while still achieving high image brightness through optimized light utilization.
2Illumination intensity
If the illumination beam angle is increased to make the image brighter, then more light reaches the micromirror element, but the projection beam quality deteriorates due to overlapping
Solution Approach 1:
The patent resolves the beam overlap issue by changing the angular dimension of the illumination path. By setting the illumination optical axis at angle (2A+α) from the micromirror normal, the illumination beam is directed along a different angular dimension than the projection beam, allowing both beams to coexist without overlap and maintaining high light intensity while preserving projection beam quality.
3Device complexity
If the incidence angle is set to 24° as in conventional designs, then the optical path is simplified, but the left-right brightness balance deteriorates
Solution Approach 1:
The patent changes the critical parameter of the illumination incidence angle from the conventional 24° to a new value of (2A+α), where A is the micromirror tilt angle and α is a positive offset. This parameter change optimizes the optical path to prevent beam overlap and achieve symmetric left-right brightness distribution, while the optical path structure itself remains relatively simple.
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 enhances image brightness and maintains uniform brightness distribution, preventing image quality degradation by optimizing the projection beam's path and reducing beam overlap, resulting in a more balanced and brighter projected image.
Implementation Method 1
a micromirror element 23... forms a light image by reflected light
Implementation Method 2
causes illumination light whose incidence angle is (2A+α)° (α>0) to enter the micromirror element
Implementation Method 3
The projector lens unit 24 enlarges a light image formed by the micromirror element 23 and projects the enlarged image
Data Source
AI summary
There is provided a projection apparatus including a light source, a micromirror element which tilts a plurality of micromirrors arranged in an array +A° or −A° (A>0) separately from an array surface to form a light image with light components reflected by the plurality of micromirrors, an illumination optical system which uses light emitted from the light source and causes illumination light whose incidence angle is (2A+α)° (α>0) to enter the micromirror element from a direction to which a less than 45° turn is made from a narrow side direction of the array surface of the micromirror element, and a projection optical system which a light image output from the micromirror element enters and which projects the light image onto a projection object.