Interleaved Laser Scanning for Miniature Projector Brightness
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Solution Overview
Problem
Miniature laser projectors exhibit low light output, limiting their utility due to safety and performance concerns associated with increasing laser power, and existing methods to enhance brightness are inefficient.
Innovation Solution
The method involves modulating scan velocity and using interleaved scanning patterns to optimize brightness, where the vertical scan velocity is adjusted based on brightness levels, and light beams are scanned in wave patterns along both axes to increase peak brightness and maintain image uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If laser power is increased to improve brightness, then illumination intensity is improved, but safety risks and heat generation worsen
Solution Approach 1:
The patent applies periodic action by using pulsed laser operation instead of continuous wave operation. The laser emits light in periodic pulses synchronized with the scan lines, allowing the laser to be off during retrace periods and between scan lines. This periodic emission increases peak brightness during active scanning while reducing overall power consumption and heat generation, thereby improving brightness without proportionally increasing safety risks
Solution Approach 2:
The patent implements dynamics by modulating the laser power dynamically during the scanning process. The laser power is adjusted based on the scan position and brightness requirements of different image regions. This dynamic power modulation allows the system to achieve higher peak brightness when needed while consuming less average power, resolving the contradiction between brightness and safety/heat
2Illumination intensity
If laser power is increased to improve brightness, then illumination intensity is improved, but power consumption worsens
Solution Approach 1:
The laser operates in periodic pulses synchronized with the horizontal scan lines, remaining off during vertical retrace periods and between active scan lines. This periodic operation delivers high peak power during brief intervals to achieve adequate brightness while consuming significantly less average power compared to continuous operation, thus improving brightness without proportionally increasing power consumption
Solution Approach 2:
The system dynamically adjusts laser power based on real-time scanning position and image brightness requirements. By modulating power only when and where needed, the system achieves optimal brightness efficiency while minimizing overall power consumption
3Productivity
If scan velocity is increased to improve scanning efficiency, then productivity is improved, but illumination intensity worsens
Solution Approach 1:
The scan velocity is dynamically modulated during the horizontal scanning process. The beam moves faster during retrace periods and slower during active scan lines where image formation occurs. This velocity modulation increases scanning efficiency by reducing retrace time while maintaining adequate brightness during active scanning by spending more time illuminating each scan line
4Productivity
If bi-directional scanning is used to maximize laser use efficiency, then productivity is improved, but manufacturing precision worsens
Solution Approach 1:
The patent inverts the conventional approach by using unidirectional scanning (scanning only in one direction during active image formation) rather than bi-directional scanning. The laser beam scans from left to right during active lines and rapidly returns during retrace periods without forming image data. This unidirectional approach improves image uniformity by eliminating the complexity of synchronizing bidirectional scanning, while maintaining laser efficiency through pulsed operation during active scan lines only
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 effectively increases peak brightness and maintains image uniformity by ensuring the laser beam spends more time on bright areas and less time on dark areas, while minimizing power consumption and heat generation, thus enhancing the operational efficiency of miniature projectors.
Implementation Method 1
The horizontal scan motion is created by running the horizontal axis at its resonant frequency, which is typically about 18 KHz
Implementation Method 2
Miniature laser projectors... These laser-based units typical display power in the order of only 1 mW
Data Source
AI summary
A method of operating a miniature projector that comprises: receiving image data to project; generating light beams for a screen; scanning the light beams according to a first pattern from a first edge to an ending edge in the screen to form at least one image, the first pattern being a wave pattern of scan lines such that amplitudes oscillate along a first axis as the beams progressively scan along a second axis, the second axis being substantially perpendicular to the first axis, wherein the first pattern has a first oscillation from the first edge that is directed in a first direction along the first axis; and scanning the light beams according to a second pattern from a second edge to a second ending edge for the screen to form at least another image, the second pattern being a wave pattern of scan lines such that amplitudes oscillate along the first axis as the beams progressively scan along the second axis, wherein the second pattern has a first oscillation from the second edge that is directed in a second direction along the first axis that is opposite the first direction.