Projection Optical System Focus Shift for Uniform Illumination
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Solution Overview
Problem
Existing projection-type image display apparatuses face challenges in achieving uniform illumination without spatial unevenness, particularly when used as both image display and illumination devices.
Innovation Solution
A projection-type image display apparatus with a light source unit, image generating unit, light-guide optical system, and controller that allows for a display mode and an illumination mode, where the controller focuses illumination light at a position offset from the projection surface in the illumination mode to achieve high spatial uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the projection optical system focuses illumination light on the projection surface, then the illumination intensity is high, but the spatial uniformity of illumination deteriorates
Solution Approach 1:
The patent changes the focusing parameter of the projection optical system by adjusting the focus position along the optical axis. In illumination mode, the focus is positioned at a location different from the projection surface (either in front of or behind it), which transforms the concentrated focused light into diffused illumination light, thereby achieving both high illumination intensity and high spatial uniformity simultaneously
2Manufacturing precision
If the apparatus is designed for image display function, then the image projection quality is high, but the illumination function quality deteriorates
Solution Approach 1:
The patent implements dynamic adaptability by enabling the projection optical system to switch between different focusing states based on the operating mode. The controller adjusts the focus position dynamically: when in image display mode, the system focuses on the projection surface for clear images; when in illumination mode, the system defocuses to provide uniform illumination. This dynamic adjustment allows a single apparatus to excel at both functions without compromise
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
Enables the emission of high-quality, spatially uniform illumination light, improving the apparatus's functionality as both an image display and illumination device.
Implementation Method 1
The controller controls the projection optical system to focus illumination light from the projection optical system at a position different from the projection screen, in the illumination mode
Implementation Method 2
a light-guide optical system that guides the light from the light source unit to the image generating unit
Data Source
AI summary
A projection-type image display apparatus includes a light source unit, an image generating unit that generates image light according to an input video signal, a light-guide optical system that guides the light from the light source unit to the image generating unit, a projection optical system that projects the image light generated by the image generating unit, and a controller. The controller has a display mode in which the image light is projected and an illumination mode in which the light from the light source unit is emitted as illumination light. The controller controls the optical system to focus illumination light from the projection optical system on a projection surface, in the display mode, and to focus illumination light from the projection optical system at a position different from the projection screen, in the illumination mode.