Projector Tilt Projection Illuminance Compensation
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Solution Overview
Problem
Tilt projection in projectors results in uneven illuminance, with the upper part of the projected image being darker than the lower part, leading to illuminance issues.
Innovation Solution
A projector design that includes a diffraction element which converts light into 0-th order and diffracted light, with the diffraction element adjusted to compensate for illuminance unevenness by varying the intensity of diffracted light based on its angle relative to the 0-th order light, ensuring that image light with higher intensity is projected to areas with reduced illuminance, and an optical path conversion element to minimize projector size and optimize light use efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If tilt projection is performed to project image light obliquely upward onto a screen, then the projector can be used in more installation positions and scenarios, but illuminance unevenness occurs where the upper part of the image is darker than the lower part
Solution Approach 1:
The patent applies local quality by creating an asymmetric intensity distribution in the diffracted light that specifically compensates for the local illuminance deficiency in the upper region of the projected image. The diffraction element is designed to concentrate diffracted light intensity toward the upper side, creating a non-uniform intensity profile that matches the inverse of the illuminance unevenness pattern, thereby achieving uniform overall illuminance across the image area.
Solution Approach 2:
The patent utilizes parameter changes by modifying the intensity distribution parameter of the diffracted light through the diffraction element. By adjusting the diffraction pattern and intensity characteristics of the element, the system changes the light intensity parameters to compensate for the illuminance unevenness caused by tilt projection, transforming the light distribution to achieve uniform illuminance while maintaining the tilted projection geometry.
2Illumination intensity
If a diffraction element is used to compensate for illuminance unevenness by varying diffracted light intensity, then illuminance uniformity is improved, but the device complexity increases due to additional optical elements and adjustment mechanisms
Solution Approach 1:
The patent applies universality by designing the diffraction element to perform multiple functions simultaneously: it diffracts the light beam into 0-th order and diffracted light, compensates for illuminance unevenness through asymmetric intensity distribution, and maintains compact system geometry. This multi-functional element reduces the need for additional separate compensation devices, thereby limiting the increase in device complexity while achieving illuminance uniformity.
Solution Approach 2:
The patent merges the illuminance compensation function with the existing diffraction element in the optical path. Instead of adding a separate compensation device, the patent combines the compensation capability into the diffraction element itself by designing its intensity distribution characteristics, thereby integrating multiple functions into a single component and minimizing the increase in overall 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
Effectively reduces illuminance unevenness during tilt projection by ensuring consistent image brightness across the projected area, improving image quality and minimizing projector size while maintaining high light use efficiency.
Implementation Method 1
a diffraction element that converts light from the light source device into 0-th order light and diffracted light
Data Source
AI summary
A projector includes a light source device, a diffraction element that converts light from the light source device into 0-th order light and diffracted light, a light modulation device that modulates the diffracted light so as to form image light, and a projection optical system that emits projected light having a chief ray which is tilted with respect to an optical axis of the image light incident from the light modulation device. Defining a reference plane as a plane which is perpendicular to a plane including the optical axis and a chief ray of the projected light and includes the optical axis, a plane including an optical axis of the 0-th order light and a chief ray of the diffracted light intersects the reference plane.