Projection Illumination Spoke Time Color Stability
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Solution Overview
Problem
Existing illumination systems for projection devices experience undesired color effects during spoke time due to constant color changes, which can be mitigated by switching off the light source, but this reduces brightness, or requires complex compensation techniques to utilize spoke time light efficiently.
Innovation Solution
The illumination system configures the drive-unit to switch off the first light-emitting unit during a part of the spoke time, allowing the second light-emitting unit to determine the color of the light emitted, ensuring a substantially constant color that can be easily used by the projection device without complex compensation algorithms, and boosts the intensity of the second light-emitting unit to match non-spoke time brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the light source is switched off during spoke time to prevent color changes, then color stability is improved, but brightness is reduced
Solution Approach 1:
The light source is divided into multiple light-emitting units (first, second, third units) that can be independently controlled. During spoke time, specific units are switched off while others remain active, preventing color changes while maintaining overall brightness through the contribution of remaining units.
Solution Approach 2:
Different light-emitting units are positioned at different locations around the color wheel. By selectively switching off units based on the spoke's angular position, the system maintains color stability in the affected region while preserving brightness through units in other regions.
2Illumination intensity
If complex compensation techniques are used to utilize spoke time light, then brightness is improved, but device complexity increases
Solution Approach 1:
The patent extracts and eliminates the need for complex compensation algorithms by using a straightforward approach: selectively switching off specific light-emitting units during spoke time. This simple control strategy achieves both brightness maintenance and color stability without requiring complex processing.
3Illumination intensity
If the light source remains on during spoke time to maintain brightness, then brightness is improved, but color changes occur
Solution Approach 1:
The system dynamically adjusts which light-emitting units are active based on the real-time position of the color wheel spoke. The drive unit continuously monitors spoke position and selectively switches units on or off, creating a dynamic control strategy that adapts to the rotating color wheel while maintaining both brightness and color stability.
Data Source
Figure 1A~1C
Figure 2A~2D
Figure 2E
AI summary
The invention relates to an illumination system (100), a projection device, and a color wheel (20, 22, 24). The illumination system comprises a light source comprising a first light-emitting unit (50) and a second light-emitting unit each emitting light towards a light output window (110). The illumination system comprises the color wheel comprising a plurality of color segments (R, G, B), a boundary between two adjacent color segment being a spoke (40). The first light-emitting unit, the second light-emitting unit and the spoke are configured for preventing the spoke when transiting the optical path (80) between the light source and the light output window to simultaneously transit a first optical path between the first light-emitting unit and the light output window and a second optical path between the second light-emitting unit and the light output window. The illumination system further comprises a drive unit (92) which is configured for switching off the first light-emitting unit during a time interval (pI) when the spoke transits the first optical path. The effect of the illumination system according to the invention is that the color of the light emitted during the spoke time does not change gradually but changes relatively abruptly enabling the projection device to use the light emitted during the spoke time without the need for complex compensation techniques.