Laser Scanner Color Shift Correction Using Time Difference Detection
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Solution Overview
Problem
Conventional image forming apparatuses face challenges in accurately correcting color shift due to temperature variations within the printer, as existing methods require temperature sensors for precise correction, which can fail and lead to inaccurate color alignment.
Innovation Solution
An image forming apparatus is designed with a frame, a polygon mirror, multiple laser generators, first and second sensors, a storage unit, a measuring unit, and a controller, where the sensors detect laser beams at different positions to measure time differences and calculate shifts, allowing for correction of color shifts without the need for a temperature sensor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a temperature sensor is separately provided between two synchronization detecting means to correct shift of image length, then color shift correction accuracy is improved, but device complexity increases and reliability decreases due to additional failure points
Solution Approach 1:
The invention extracts the temperature measurement function from a separate temperature sensor and integrates it into the existing synchronization detection system. The synchronization detecting means now serves dual purposes: detecting synchronization signals and measuring temperature, thereby eliminating the need for separate temperature sensors while maintaining correction accuracy
Solution Approach 2:
The synchronization detecting means is designed to perform multiple functions: detecting the synchronization signal for magnification error correction and simultaneously measuring temperature for image length shift correction. This multi-functionality reduces the total number of sensors and improves system reliability
2Measurement precision
If a temperature sensor is separately provided to correct image shift, then color shift correction is improved, but reliability worsens due to sensor abnormal operation
Solution Approach 1:
The synchronization detecting means performs both synchronization detection and temperature measurement functions. Since this component is already essential for the laser beam scanning system, its failure would cause complete system malfunction anyway, making the system more reliable by reducing the number of independent failure points
Solution Approach 2:
The temperature measurement function is merged with the synchronization detection function in the same detecting means. This consolidation reduces the number of independent components and potential failure points, thereby improving overall system reliability while maintaining correction accuracy
3Measurement precision
If two-point synchronizing method is used to correct magnification error shift, then magnification error correction is improved, but image position correction worsens due to position variation between synchronization detecting means
Solution Approach 1:
The invention changes the measurement parameter from spatial position (which varies with temperature) to time interval (which remains stable). By measuring the time interval between synchronization signals detected at two different positions, the system compensates for temperature-induced position variations while maintaining correction accuracy
Solution Approach 2:
The invention transitions from measuring spatial position (one-dimensional) to measuring time interval (another dimension). This dimensional change allows the system to bypass temperature-induced spatial variations and achieve accurate image position correction through time-based measurement
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 solution enables accurate correction of color shifts caused by temperature variations, reducing the reliance on temperature sensors and improving the precision of image formation by using detected time differences and stored correspondence information to adjust laser beam outputs.
Implementation Method 1
The first sensor is disposed at the frame, and located at a first position to detect a laser beam deflected by the deflection surface. The second sensor is disposed at the frame, and located at a second position to detect a laser beam deflected by the deflection surface.
Implementation Method 2
The polygon mirror is disposed at the frame, and has a rotational shaft and a deflection surface rotatable about the rotational shaft. The plurality of laser generators is disposed at the frame. Each of the plurality of laser generators outputs a laser beam to the deflection surface. The laser beam deflected by the deflection surface is irradiated onto the photosensitive surface to scan the photosensitive surface
Implementation Method 3
The plurality of laser generators is disposed at the frame. Each of the plurality of laser generators outputs a laser beam to the deflection surface.
Data Source
AI summary
In an image forming apparatus, a polygon mirror, a plurality of laser generators, a first sensor, and a second sensor are disposed at a resin frame. A laser beam outputted from each of the laser generators and deflected by a deflection surface is irradiated onto a surface of a photosensitive drum to scan the surface over a scan part. The first sensor is disposed at a first position to detect a laser beam deflected by the deflection surface. The second sensor is disposed at a second position to detect a laser beam deflected by the deflection surface. A storage unit stores correspondence information indicating shift of the scan part from a reference scan part in relation to time difference between detections of the laser beam by the first and second sensor. A controller controls the laser generator to output a laser beam based on the shift of the scan part.