Laser Diode Modulation via Polygon Mirror Segmentation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing electrophotographic devices face challenges in adjusting scanning resolution and image transfer rate without compromising print quality, as typical laser diodes cannot handle drastic changes in laser power, leading to increased complexity in driver circuitry and potential inconsistencies in print quality.
Innovation Solution
The system splits each line of image data across at least two scan lines, with the laser source modulated based on the image data during specific sweeps of the beam, allowing for flexible adjustment of image transfer characteristics without requiring drastic changes in laser power, by utilizing a controller to manage the modulation of the laser source across multiple facets of a rotating polygon mirror.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If the image transfer rate is reduced to one half of the full speed without changing the scanning mirror speed, then double scan line addressability is achieved improving image quality, but the laser power needs to be reduced by one half which may not be within the operating range of typical laser diodes
Solution Approach 1:
The patent divides a single scan line into multiple segments (first scan line portion and second scan line portion) that are written by different facets of the polygon mirror. This segmentation allows the system to maintain full laser power while achieving the effect of double scan line addressability by distributing the image data across multiple scan line segments, eliminating the need to reduce laser power.
2Power
If pulse width modulation is used to reduce laser power output by one half, then the desired power reduction is achieved, but the complexity of the laser diode driver circuitry increases
Solution Approach 1:
Instead of using pulse width modulation to reduce laser power, the patent segments the scan line into multiple portions written by different mirror facets. This allows the laser to operate at full power continuously while still achieving the effective power reduction needed for double scan line addressability, thereby avoiding the complexity of PWM driver circuitry.
3Manufacturing precision
If the photoconductive surface speed is reduced to achieve double scan line addressability, then image quality improves, but the fusing operation time must be extended which requires slower medium transport
Solution Approach 1:
The patent segments each scan line into multiple portions that are written by different facets of the polygon mirror during the same pass. This segmentation enables double scan line addressability without reducing the photoconductive surface speed, thereby maintaining the original fusing operation timing and medium transport speed while still improving image quality.
4Manufacturing precision
If the scanning mirror speed is modified to change print resolution, then resolution is improved, but the image transfer rate must be adjusted which affects productivity
Solution Approach 1:
The patent segments scan lines into multiple portions written by different mirror facets, allowing the system to achieve higher effective resolution through multiple scan line passes without changing the scanning mirror speed. This maintains the original image transfer rate and productivity while improving print resolution through the segmented writing approach.
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 enables flexible adjustment of image transfer characteristics, maintaining print quality across different scanning resolutions and image transfer rates without the need for significant laser power adjustments, reducing complexity in the laser diode driver circuitry and minimizing the impact on print quality.
Implementation Method 1
a laser source, a photoconductive surface... an imaging system forms a latent image by exposing select portions of an electrostatically charged photoconductive surface to laser light
Implementation Method 2
a scanning device having a plurality of deflecting surfaces arranged such that a beam emitted by the laser source sweeps in a scan direction across the photoconductive surface each time a new one of the deflecting surfaces intercepts the beam
Implementation Method 3
the photoconductive surface advances in a process direction that is orthogonal to the scan direction
Data Source
AI summary
An imaging system comprises a laser source for emitting a beam, a photoconductive surface, a scanning device and a controller. The controller designates at least a first part and a second part of each line of image data, corresponding to a first part and a second part of each associated sweep of the beam. The laser source is modulated based upon the first part of the line of image data during the first part of a first one of the associated sweeps of the beam. The laser source is not modulated according to image data for the second part of the first one of the sweeps. During the first part of a second one of the associated sweeps of the beam, the laser source is not modulated based upon image data. However, the laser source is modulated based upon the second part of the line of image data during the second part of the second one of the sweeps.