Optical Scanning Apparatus Speed Compensation Feedback Control
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Solution Overview
Problem
Existing optical scanning apparatuses face challenges in maintaining uniform scanning speed in the sub-scanning direction, leading to uneven brightness and scanning distortion in projected images due to variations in the moving speed of the reflection surface, which affects the density of scan lines and light reception intervals.
Innovation Solution
The optical scanning apparatus includes a light deflector and a controller that adjusts the drive signal based on the number of light receptions at multiple positions within a predetermined range, ensuring uniform scanning speed by compensating for variations in the moving speed of the reflection surface, thereby controlling the light deflector to maintain consistent scan line density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the light deflector operates without speed compensation, then the device complexity is reduced, but the scanning speed uniformity and image quality deteriorate due to variations in reflection surface moving speed
Solution Approach 1:
The patent implements a feedback control mechanism where the light receiver detects the actual position of the scanned light spot and feeds this information back to the controller. The controller then adjusts the drive signal to the light deflector based on the detected position, creating a closed-loop system that compensates for speed variations in the reflection surface without requiring complex mechanical modifications
Solution Approach 2:
The patent replaces complex mechanical speed regulation mechanisms with an optical-electronic control system. Instead of using mechanical devices to physically regulate the scanning speed, the system uses light detection and electronic signal processing to sense and compensate for speed variations, thereby simplifying the mechanical structure while maintaining scanning uniformity
2Ease of operation
If the drive signal is not adjusted for speed variations, then the ease of operation is improved, but the manufacturing precision and image quality deteriorate due to uneven scan line density
Solution Approach 1:
The system implements self-service control where the optical scanning apparatus automatically detects and corrects its own scanning speed variations. The light receiver monitors the actual scanning performance and the controller autonomously adjusts the drive signal without requiring external intervention, maintaining both operational simplicity and scanning precision
Solution Approach 2:
The feedback mechanism continuously monitors the scan line density through light reception detection and automatically adjusts the drive signal to maintain uniform scanning. This self-regulating system preserves ease of operation while ensuring manufacturing precision through automatic compensation of speed variations
3Measurement precision
If multiple light receivers are used to detect position variations, then the measurement precision is improved, but the device complexity increases due to additional components
Solution Approach 1:
The patent divides the detection function into multiple light receivers positioned at different locations to independently detect position variations. By segmenting the detection task across multiple sensors, the system achieves comprehensive position monitoring and high measurement precision while maintaining a modular and manageable device structure
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 suppresses uneven brightness and scanning distortion by maintaining uniform scan line density and improving the quality of projected images by adjusting the drive signal in response to light reception variations, ensuring consistent image projection.
Implementation Method 1
a light deflector to deflect light from a light source at least in a sub-scanning direction to perform optical scanning on a scan region
Implementation Method 2
a light receiver to receive, within a predetermined range in the sub-scanning direction, light used for optical scanning performed by the light deflector
Data Source
AI summary
An optical scanning apparatus, an image projecting apparatus, and a mobile object. The optical scanning apparatus includes a light source to emit light, a light deflector to deflect the light emitted from the light source at least in a sub-scanning direction to perform optical scanning on a scan region, a light receiver to receive, within a predetermined range in the sub-scanning direction, the light used for optical scanning performed by the light deflector, and a controller to control the light deflector based on a number of times of light reception of the light receiver at a plurality of positions in the sub-scanning direction within the predetermined range. The image projecting apparatus includes the optical scanning apparatus, and a projection optical system configured to project light emitted from the optical scanning apparatus to the scan region.