DMD Mask Plate Rhombus Aperture Illumination Rectification
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Solution Overview
Problem
The existing projection type image display apparatus using a digital micromirror device (DMD) faces challenges in preventing harmful light creation on the boundary of the light transmitting and light shielding portions of the cover, leading to inefficient light modulation and unwanted illumination in the peripheral areas, which affects image quality.
Innovation Solution
The apparatus incorporates a mask plate with a rhombus-shaped mask aperture or an inclined mask plate to reshape the illumination area into a rectangle, ensuring it conforms to the element face of the DMD, thereby preventing harmful light and maintaining dark areas in the projected image.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the light axis is inclined to improve reflection efficiency of mirror elements, then the illumination area becomes rhombus shaped which cannot fit within the rectangular light transmitting portion, but the harmful light is created on the boundary of light transmitting and light shielding portions
Solution Approach 1:
The patent applies preliminary action by pre-shaping the illumination area to a rectangular configuration before it reaches the DMD element face. The illumination optical system is designed to form a rectangular illumination area that matches the rectangular light transmitting portion, preventing harmful light from reaching the boundary between light transmitting and light shielding portions before reflection efficiency is compromised by the inclined light axis
Solution Approach 2:
The patent applies local quality by creating different illumination characteristics in different regions. The illumination area is precisely controlled to be rectangular and confined within the light transmitting portion, ensuring that only the intended rectangular region receives illumination while the boundary regions remain dark, thus eliminating harmful light without affecting the overall reflection efficiency
2Manufacturing precision
If the illumination area is stretched to cover the element face completely, then the peripheral area around the element face is illuminated, but unnecessary illumination in peripheral areas causes glimmering of dark areas in projected image
Solution Approach 1:
The patent applies preliminary action by pre-defining the illumination area boundaries to precisely match the element face boundaries. The illumination optical system is configured to illuminate only the required rectangular area corresponding to the element face, preventing any spill-over illumination to peripheral areas before the light reaches the DMD, thus eliminating glimmering in dark areas while ensuring complete coverage of the element face
3Object-affected harmful factors
If a rectangular mask aperture is used to conform to the light transmitting portion, then the appearance is improved and harmful light is prevented, but the illumination area becomes rhombus shaped which does not cover the element face completely
Solution Approach 1:
The patent applies preliminary action by pre-shaping the illumination area to a rectangular form that matches both the light transmitting portion and the element face. The illumination optical system is designed to create a rectangular illumination area that simultaneously conforms to the rectangular mask aperture and completely covers the rectangular element face, eliminating the rhombus-shaped mismatch that occurs with inclined light axes
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 effectively prevents harmful light on the boundary of the light transmitting and light shielding portions, ensuring precise illumination and maintaining dark areas in the projected image, enhancing image quality by reshaping the illumination area to match the DMD element face.
Implementation Method 1
a mask plate with a substantially rhombus mask aperture, which passes the illumination light
Implementation Method 2
each of which elements can swing between an ON position to reflect the illumination light toward the projection optical system and an OFF position to reflect the illumination light off the projection optical system
Implementation Method 3
a light transmitting portion 107 that transmits the illumination light heading to an element face 102a of the mirror unit 102
Implementation Method 4
a light shielding portion 108 that surrounds the light transmitting portion 107 to block the illumination light heading off the element face 102a
Data Source
AI summary
A DMD (digital micromirror device) includes a substantially rectangular element face made up of plural mirror elements arranged in a matrix. The DMD is provided with a light shielding cover having a light transmitting portion which corresponds to the element face. Radiated from the illumination optical system including a rod integrator, the illumination light enters the element face, on a flat surface including the diagonal line of the element face, at an inclined angle with respect to the normal to the element face. Near a light exit face of the rod integrator, a mask plate is disposed to regulate a part of the illumination light. The mask plate has a mask aperture of substantially rhombus shape. The illumination light passing the mask aperture is reshaped so that an illumination area can be a substantially rectangular shape on the element face.