Projection Illumination System with Dual Intensity Segmentation
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Solution Overview
Problem
Existing image projection systems using spatial light modulating devices suffer from blurring and 'color break-up' effects when displaying moving images, due to the rapid decay of image intensity and temporal sequencing of color filters, which limits the quality of fast-moving image reproduction.
Innovation Solution
The system employs a dual illumination strategy within an image frame time, where a high-intensity illumination interval is followed by a reduced-intensity interval, allowing for enhanced bit depth representation during the latter, with the illumination levels adjusted to maintain image quality by using a color wheel with varying transmittance segments or separate light sources driven at different current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the image is displayed using a light modulating means with sequential color illumination, then the color reproduction is achieved, but motion blur and image break-up occur due to the temporal sequencing and limited hold effect
Solution Approach 1:
The illumination period is segmented into multiple subframes, with each subframe displaying a specific color component (red, green, blue) sequentially. This segmentation allows the light modulating means to update the image multiple times within a single frame period, reducing motion blur while maintaining color reproduction through temporal multiplexing
Solution Approach 2:
The system employs periodic illumination sequences where color filters are cycled through red, green, and blue segments in a repeating pattern. By synchronizing the light modulating means updates with this periodic illumination, the system achieves stable color reproduction without motion blur artifacts
2Illumination intensity
If the illumination is provided continuously throughout the frame time, then sufficient light output is maintained, but motion blur increases due to the extended exposure time
Solution Approach 1:
Instead of continuous illumination, the system uses periodic illumination divided into discrete color segments. Each color segment illuminates the light modulating means for a specific duration, then switches to the next color. This periodic action reduces the effective exposure time for each color component, minimizing motion blur while maintaining overall light output through sequential color cycling
Solution Approach 2:
The system maintains continuous useful action by ensuring that at least one color segment is illuminated at any given time, with no dark gaps between color sequences. The illumination continuously cycles through red, green, and blue segments, ensuring constant light output while reducing motion blur through rapid sequential updates
3Manufacturing precision
If the light modulating means is updated multiple times within a frame, then motion blur is reduced, but the complexity of timing and color sequencing increases
Solution Approach 1:
The system performs preliminary action by pre-calculating and storing the color sequence timing information in a lookup table or memory structure. The controller retrieves the appropriate color segment timing information in advance, eliminating the need for complex real-time calculations and reducing the computational burden while maintaining precise timing control
Solution Approach 2:
The system implements feedback mechanisms where the controller monitors the actual illumination timing and adjusts the light modulating means updates accordingly. This feedback ensures synchronization between the color wheel rotation and the light modulating means refresh rate, maintaining image quality while simplifying the timing control through adaptive adjustment
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 significantly reduces motion blur and 'image break-up' effects, enabling high-quality projection of fast-moving images by optimizing the illumination duration and intensity distribution across the frame time, while maintaining sufficient bit depth and brightness.
Implementation Method 1
a color wheel which is placed in the optical path, which color wheel consist of red, green, blue and in some cases also white filter segments
Implementation Method 2
a light modulating means, e.g. an LCD, LCOS or DLP device, which is illuminated by the light which was filtered by the color wheel. The modulation of the light modulating means is adapted to the sequence of colors that illuminate the device
Data Source
Figure 1a~1b
Figure 2
Figure 3~4
AI summary
A projection system for projecting images is described. The projection system has an illumination system for generating an illumination beam comprising sequential color portions. The illumination beam is guided to a light modulating means based on light valves, which allows modulating an impinging illumination beam such that it comprises image information about an image to be displayed. The images are refreshed after an image frame time tframe. The illumination of the light modulating means for generating an image is substantially performed during a first time interval of the image frame time tframe. The latter results in an improved displaying of fast moving images.