Curved Light Shielding Bodies for Uniform Illumination in Projection Displays
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Solution Overview
Problem
Projection displays face challenges in achieving high contrast due to light leakage from optical elements and uneven illumination caused by light shielding plates, particularly in dark environments where dark images appear too bright, leading to low contrast.
Innovation Solution
A projection display system with a light-amount control mechanism using a pair of light shielding bodies that turn like a double door, bent into a V shape to adjust light levels without causing uneven illumination, incorporating an integrator lens for uniform illumination and a turning mechanism controlled by a signal detector and controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a flat light shielding plate is used to control light amount, then light control function is achieved, but uneven illumination and linear unevenness occur on the light valve
Solution Approach 1:
The light shielding plate is changed from a flat shape to a curved shape that follows the spherical surface of the second lens array. This curvature ensures that the light shielding plate does not create linear unevenness when viewed from the optical axis, while still effectively controlling the amount of light reaching the light valve.
Solution Approach 2:
The light shielding plate is designed with different properties in different regions: the outer peripheral portion has a different curvature radius than the inner portion, allowing each region to contribute differently to light control while maintaining overall illumination uniformity across the light valve surface.
2Illumination intensity
If the tip of the light shielding plate is positioned at the center of curvature of the second lens array, then light control is effective, but the rectangular plane of the light shielding plate is imaged onto the light valve causing linear unevenness
Solution Approach 1:
By curving the light shielding plate to match the spherical surface of the second lens array, the plate avoids creating a rectangular image on the light valve. The curved geometry ensures that no sharp edges or linear features are projected onto the light valve, eliminating linear unevenness while maintaining effective light control at the center of curvature position.
3Device complexity
If a flat light shielding plate is used, then结构简单 (structure is simple), but satisfactory contrast cannot be achieved due to light leakage and uneven blocking
Solution Approach 1:
The curved design of the light shielding plate improves contrast performance by eliminating uneven light blocking and preventing linear unevenness on the light valve. While the shape becomes more complex, the overall structure remains relatively simple, achieving a balance between structural simplicity and reliable contrast performance.
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 solution enables continuous light control, improving contrast and maintaining uniform illumination, allowing for consistent and satisfactory image display even in dark environments.
Implementation Method 1
an integrator lens provided on an optical path between the light source and the light valve and making uniform an illumination distribution of light applied from the light source to the light valve
Implementation Method 2
a light-amount control mechanism provided on the optical path and including a pair of light shielding bodies that turn like a double door in order to adjust the amount of light applied from the light source to the light valve
Data Source
AI summary
The invention provides a projection display that achieves continuous light amount control with ease and without causing unevenness of illumination of light applied to a light valve responsive to a video signal, thereby allowing constant image display with satisfactory contrast. The projection display of the invention includes a light valve (2); a light source (3a) generating light applied to the light valve (2); an integrator lens (4) provided on an optical path between the light source (3a) and the light valve (2) and making uniform the illumination distribution of light applied from the light source (3a) to the light valve (2); and a light amount control system (9) provided on the optical path and including a turning mechanism (9a) which turns like a set of double doors in order to adjust the amount of light applied from the light source (3a) to the light valve (2). The turning mechanism (9a) is bent into a V shape in a direction to reduce the amount of light (to block the light).