Ultra-Short Throw Projection Barrel Geometry for Uniform Illuminance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for image display apparatuses with ultra-short throw projection capabilities that can maintain even illuminance across a projection image, particularly at the center and peripheral areas, while being compact and efficient in design, as existing systems often suffer from uneven illuminance and bulkiness due to the constraints of short focal lengths and optical system configurations.
Innovation Solution
The image display apparatus incorporates a specific optical system configuration where the outside diameter of the barrel on the light entering side (φ) and the distance between the reflection planes and the barrel front end (H) satisfy the equation φ < 0.71H + 8.5, along with a toroidal surface for the second illumination mirror, to ensure uniform illumination distribution and compactness, using a projection lens system and a digital micromirror device (DMD) for optical modulation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of moving object
If the projection distance is reduced to achieve ultra-short throw capability, then the projection distance is improved, but the illuminance distribution becomes uneven
Solution Approach 1:
The patent applies local quality by using a toroidal surface for the second illumination mirror instead of a conventional spherical or flat surface. This specific surface geometry is designed to distribute light uniformly across the projection plane, particularly addressing the uneven illuminance distribution problem in ultra-short throw projections. The toroidal shape is specifically engineered to control light rays at different locations on the projection plane, ensuring even illumination from the center to the periphery.
Solution Approach 2:
The patent employs parameter changes by establishing a specific mathematical relationship between the barrel diameter (φ) and the distance from the reflection planes to the barrel front end (H), expressed as φ < 0.71H + 8.5. This parameter constraint is optimized to achieve uniform illuminance distribution while maintaining ultra-short projection distance. By carefully controlling these geometric parameters, the system achieves both compactness and even light distribution.
2Volume of moving object
If the focal length is reduced to achieve compactness, then the device size is improved, but the illuminance at peripheral areas decreases
Solution Approach 1:
The patent applies spheroidality by employing a toroidal surface (a type of curved surface) for the second illumination mirror. This curved surface is specifically designed to redirect light rays toward the peripheral areas of the projection plane, compensating for the natural light falloff that occurs in compact optical systems. The toroidal curvature is engineered to maintain even illuminance distribution across the entire projection area despite the reduced focal length.
Solution Approach 2:
The patent uses a composite optical system combining multiple optical elements with specific functions: the DMD array for light modulation, the toroidal second illumination mirror for uniform light distribution, and the projection lens system for image formation. This composite approach allows the system to achieve both compactness and even illuminance distribution by leveraging the complementary strengths of each component.
3Volume of moving object
If the barrel diameter is reduced to achieve compactness, then the device size is improved, but the illuminance distribution becomes uneven
Solution Approach 1:
The patent applies parameter changes by establishing the specific constraint φ < 0.71H + 8.5 that relates the barrel diameter to the distance parameter H. This mathematical relationship is optimized to maintain even illuminance distribution while minimizing the barrel diameter. By carefully controlling this parameter relationship, the system achieves compactness without sacrificing light distribution uniformity.
Solution Approach 2:
The patent uses a toroidal surface (curved geometry) for the second illumination mirror to compensate for the reduced barrel diameter. This curved surface is specifically designed to redirect light rays uniformly across the projection plane, ensuring that the compact barrel size does not result in uneven illuminance distribution. The toroidal shape is specifically engineered to handle the light paths required for uniform distribution in compact configurations.
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 a minimum illuminance of at least 32.5% at the projection image's lower left corner, ensuring even illuminance and reducing the size of the apparatus, while maintaining high-quality projection images with a tilt angle of the flat glass that prevents excessive tilting and supports high aspect ratios in the DMD.
Implementation Method 1
a light source configured to emit light, the light source including a primary luminous body
Implementation Method 2
an optical modulation element including a plurality of reflection planes to modulate the light guided by the illumination optical system
Implementation Method 3
a projection optical system including a projection lens system and a barrel storing the projection lens system, the projection optical system projecting the light modulated by the optical modulation element onto a projection plane
Data Source
AI summary
An image display apparatus and an image display unit. The image display apparatus and the image display unit includes a light source configured to emit light, an illumination optical system including a luminous body forming device configured to form a secondary luminous body, the illumination optical system guiding the light emitted from the light source, an optical modulation element including a plurality of reflection planes to modulate the light guided by the illumination optical system, and a projection optical system including a projection lens system and a barrel storing the projection lens system, the projection optical system projecting the light modulated by the optical modulation element onto a projection plane. The barrel satisfies an equation φ<0.71H+8.5, where φ denotes an outside diameter of a front end of the barrel on a light entering side and H denotes distance between the reflection planes and the front end of the barrel.