Laser Projection Pixel Mapping with Profile Memory Compensation
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Solution Overview
Problem
Existing image projection technologies face challenges in achieving uniformly sized pixels and uniform brightness due to the variable speed of the X-mirror, leading to inconsistencies in pixel duration and brightness across the projected image.
Innovation Solution
A controller-connected profile memory system that stores time durations for selected pixels, with brightness compensation signals generated to ensure uniformity, and a compact laser assembly using multiple lasers for color projection, along with inertial and electromagnetic drives for precise scan mirror operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the X-mirror is oscillated at resonance with variable speed to scan the laser beam, then the scanning speed and resolution are improved, but the pixel brightness becomes non-uniform and pixel sizes vary across the scan line
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing the variable time durations for each pixel position in a profile memory before the actual scanning occurs. The controller retrieves these pre-determined time durations during scanning to compensate for the variable mirror speed, ensuring uniform pixel brightness and size despite the resonance-based variable speed oscillation.
2Manufacturing precision
If the X-mirror speed varies along each scan line to maintain pixel size uniformity, then pixel size consistency is improved, but the pixel brightness becomes non-uniform requiring additional compensation mechanisms
Solution Approach 1:
The patent implements feedback by using a profile memory that stores pre-calculated time duration data for each pixel position. The controller continuously retrieves this feedback information during scanning to adjust the laser pulse duration, compensating for the brightness variations caused by variable mirror speed and achieving uniform pixel brightness across the entire scan line.
3Manufacturing precision
If multiple lasers are used for color projection to improve image quality, then the color accuracy and image quality are improved, but the device complexity and power consumption increase
Solution Approach 1:
The patent applies merging by integrating multiple laser sources (red, green, and blue lasers) into a single projection system that shares common optical components including scan mirrors, profile memory, and controller. This combining approach enables full-color projection capability while reducing overall system complexity compared to separate projection systems for each color.
4Measurement precision
If the profile memory stores time durations for all scan lines to achieve precise pixel mapping, then the pixel mapping accuracy is improved, but the memory storage requirement increases significantly
Solution Approach 1:
The patent applies copying by storing the profile data for only a single representative scan line (typically the center line) in the profile memory, then reusing this copied data for all other scan lines. This approach maintains pixel mapping accuracy while dramatically reducing the memory storage requirement compared to storing separate profile data for each scan line.
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
The solution enables high-quality, compact, and portable color image projection with uniformly sized pixels and consistent brightness, suitable for various form factors and applications, while minimizing memory storage and power consumption.
Implementation Method 1
a laser assembly for generating a laser beam
Implementation Method 2
The X-mirror is oscillated, typically at resonance, at a scan frequency and at a speed that varies along each scan line
Implementation Method 3
The image is created in the raster pattern by energizing or pulsing a laser on and off at selected times, thereby illuminating selected pixels with a beam spot
Data Source
Figure 1~2
Figure 3
Figure 4~5
AI summary
A laser beam is swept by a scan mirror as a pattern of scan lines on a projection surface. The scan mirror moves at a variable speed along each scan line. Each scan line has a number of pixels. The pixels have time durations proportional to the variable speed of the scan mirror. A profile memory stores the time durations of the pixels. A controller causes selected pixels arranged along each scan line to be illuminated for the time durations stored by the profile memory to produce an image of uniform brightness and of uniformly sized pixels and in color.