DMD Micro-Mirror Sectional Brightness Control
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Solution Overview
Problem
Existing projection-type display devices, such as those using digital micromirror devices (DMDs), face challenges in adjusting the brightness of images for specific sections, limiting dynamic control over image brightness and potentially shortening the device's lifespan due to prolonged micro-mirror states.
Innovation Solution
The proposed solution involves a projection-type display device with a control unit that divides each frame into display and non-display periods, allowing individual control of micro-mirrors and light-emitting elements to adjust brightness for each section through pulse width modulation and current control, enabling precise brightness adjustment and reducing micro-mirror fixation risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the time in one inclined state of the two inclined states becomes longer, then the brightness control is improved, but the micro-mirrors are highly probably fixed to the one inclined state, shortening the lifetime of the DMD
Solution Approach 1:
The patent applies periodic action by dividing each frame into multiple sub-frames, where the inclined state of micro-mirrors is periodically switched between different states across sub-frames. This periodic switching prevents micro-mirrors from remaining in one inclined state for extended periods, thereby maintaining DMD lifetime while enabling brightness control through temporal modulation of light reflection.
Solution Approach 2:
The patent implements dynamics by making the inclined state of micro-mirrors changeable and adjustable across different sub-frames within a frame. The control unit dynamically switches micro-mirrors between first and second inclined states in different sub-frames, allowing flexible brightness control while preventing static fixation that would shorten DMD lifetime.
2Ease of operation
If the brightness of the entire image is adjusted by changing light-emitting luminance, then the brightness control is simplified, but the ability to change brightness for each section is limited
Solution Approach 1:
The patent applies segmentation by dividing the display frame into multiple sub-frames and controlling different regions (sections) of the image in different sub-frames. The control unit can assign different inclined states to different micro-mirror groups in different sub-frames, enabling independent brightness control for different image sections while maintaining overall system simplicity.
Solution Approach 2:
The patent implements local quality by allowing different sections of the image to have different brightness characteristics through selective control of micro-mirror inclined states in different sub-frames. Each region can be optimized for its specific display requirements while the overall system maintains a unified control architecture.
3Manufacturing precision
If micro-mirrors are individually driven for each sub-frame, then the image quality is improved, but the device complexity increases
Solution Approach 1:
The patent applies universality by using the same control unit and basic control logic to manage multiple sub-frames and different micro-mirror groups. The control unit performs similar operations (switching between inclined states) across all sub-frames, allowing the system to maintain high image quality through individual micro-mirror control while avoiding proportional increases in device complexity through reusable control architecture.
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 approach allows for dynamic brightness control of images for each section, enhancing the display's flexibility and potentially extending the lifespan of the DMD by minimizing prolonged micro-mirror states, while maintaining color gradation steps.
Implementation Method 1
at least one light-emitting element is caused to emit light for each sub-frame obtained by temporally dividing a frame
Implementation Method 2
light that is reflected in a prescribed direction by the micro-mirror, among light emitted by the light-emitting elements
Data Source
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Figure 3A
AI summary
Provided is a projection-type display device capable of changing the brightness of a displayed image on a section basis . A projection-type display device (10) is provided with: a reflection-type spatial optical modulation unit (20) having a plurality of movable reflection elements (21) ; a light source unit (30); and a control unit (40) that controls the reflection-type spatial optical modulation unit (20) and the light source unit (30) . The control unit (40) divides each frame (F) of a displayed image (200) into a display period (Fa) during which the light source unit (30) emits light and a non-display period (Fb) during which the light source unit (30) does not emit light. The control unit (40) further divides, among a plurality of sub-frames (SF) forming the frame (F), each of a plurality of display sub-frames (SFa) included in the display period (Fa) into a plurality of division display sub-frames (dSFa) . The control unit (40) causes at least one of a plurality of the light emitting elements of the light source unit (30) to emit light for each of the display sub-frames (SFa), and sets respective inclined states of the plurality of movable reflection elements (21) for each of the division display sub-frames (dSFa).