Laser Scan Timing Control for Color Misregistration in Printers
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Solution Overview
Problem
Existing image forming apparatuses face issues with color misregistration due to shifts in write start timing caused by changes in laser beam intensity, leading to reduced image quality and productivity, especially when frequent gain switching occurs to adjust detection sensitivity.
Innovation Solution
An image forming apparatus with a synchronous detection board that switches the gain of an optical sensor based on laser beam intensity to prevent false or missed detections, using a gain switching circuit to adjust sensitivity and minimize shifts in write start timing, thereby reducing the need for frequent color misregistration corrections.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If gain switching is performed frequently to adjust detection sensitivity based on laser beam intensity, then detection precision is improved, but write start timing shifts causing color misregistration
Solution Approach 1:
The patent applies preliminary action by determining the appropriate gain in advance based on the light intensity of the laser beam before detection begins. The controller pre-adjusts the gain of the optical sensor according to the detected light intensity, ensuring that the write start timing remains stable while maintaining high detection precision. This prevents timing shifts by establishing the correct sensitivity level before the writing process starts.
Solution Approach 2:
The patent implements feedback by using the optical sensor to detect light intensity and feed this information back to the controller, which then adjusts the gain accordingly. This closed-loop feedback mechanism ensures that the detection sensitivity is continuously optimized based on actual light conditions while maintaining stable write start timing, thereby preventing color misregistration.
2Reliability
If gain switching is performed to adjust detection sensitivity, then false or missed detections are prevented, but write start timing shifts occur
Solution Approach 1:
The controller determines the appropriate gain in advance based on the light intensity detected by the optical sensor, before the writing process begins. This preliminary gain adjustment ensures that the optical sensor operates at the correct sensitivity level throughout the writing process, preventing false or missed detections while maintaining stable write start timing.
Solution Approach 2:
The patent applies dynamics by making the gain adjustable and adaptive based on light intensity conditions. The controller dynamically switches between different gain values (first gain and second gain) depending on whether the light intensity is above or below a threshold, ensuring optimal detection reliability while minimizing timing shifts through controlled, condition-based adjustments.
3Measurement precision
If multiple gain values are used to adapt to different light intensities, then detection accuracy is improved, but device complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the detection range into two segments based on light intensity threshold: a first range where the first gain is used, and a second range where the second gain is used. This segmented approach allows the system to use multiple gain values for different conditions while keeping the control logic simple and manageable, avoiding excessive device complexity.
Solution Approach 2:
The patent implements parameter changes by adjusting the gain parameter of the optical sensor based on light intensity conditions. The controller changes the gain between two discrete values (first gain and second gain) depending on whether the light intensity is above or below a threshold, enabling adaptive detection accuracy without requiring complex continuous adjustment mechanisms.
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 maintains high-quality image formation by minimizing shifts in write start timing and reducing the frequency of color misregistration corrections, thus enhancing productivity and image quality.
Implementation Method 1
The optical sensor detects the light scanning on the surface of the photoconductor with one of multiple sensitivities; and outputs a detection signal corresponding to a light intensity of the light detected by the optical sensor
Implementation Method 2
The circuitry adjusts a light intensity of the light emitted from the light emitter and the write start timing based on the detection signal
Implementation Method 3
a deflector to deflect the light emitted from the light emitter to scan the light on the surface of the photoconductor at a write start timing
Implementation Method 4
a photoconductor to form a latent image on a surface of the photoconductor by the light emitted from the light emitter
Data Source
AI summary
An image forming apparatus includes a light emitter; a photoconductor to form a latent image on a surface of the photoconductor; a deflector to deflect light at a write start timing; an optical sensor; and circuitry. The optical sensor detects the scanning light scanning, with one of multiple sensitivities. The circuitry adjusts a light intensity of the emitted light and the write start timing based on the detection signal; switches from the one of multiple sensitivities to other of multiple sensitivities or from the other of multiple sensitivities to the one of multiple sensitivities based on the light intensity adjusted; and determines whether to perform a color misregistration correction based on a shift in the write start timing caused by a switch from the one of multiple sensitivities to the other of multiple sensitivities or from the other of multiple sensitivities to the one of multiple sensitivities.