Dynamic Threshold Adjustment for Color Misregistration Detection
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Solution Overview
Problem
Existing image forming apparatuses face challenges in accurately detecting positional deviations between achromatic and chromatic color toner images due to changes in toner amount caused by temperature or humidity, leading to erroneous detection of color misregistration.
Innovation Solution
The apparatus includes a configuration with a first image forming unit for a first color, a second image forming unit for a second color with lower reflectance, a controller for forming measurement images, a radiation unit for emitting light, a light receiving unit for detecting reflected light, and a comparison unit that adjusts the threshold value based on the measurement time period to accurately determine positional differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a fixed threshold value is used for detecting reflected light from measurement images, then the detection process is simple, but detection accuracy deteriorates when toner amount changes due to temperature or humidity
Solution Approach 1:
The threshold value for detecting reflected light is changed from a fixed value to a variable value that is dynamically adjusted based on the measurement time period. The comparison unit varies the threshold value according to the elapsed time during measurement, allowing the system to adapt to toner amount changes caused by temperature or humidity variations, thereby maintaining detection accuracy without complicating the overall process
2Reliability
If the threshold value is increased to compensate for toner amount decrease, then detection reliability improves, but measurement time increases
Solution Approach 1:
The comparison unit varies the threshold value periodically or at specific time intervals during the measurement process. Instead of continuously adjusting or using a permanently increased threshold, the system updates the threshold value at predetermined periods, achieving reliable detection while controlling the total measurement time through periodic updates rather than continuous adjustment
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 effectively reduces color misregistration by accurately detecting positional deviations even when the toner amount of the achromatic color toner decreases, ensuring precise alignment of images and minimizing errors in the final output.
Implementation Method 1
a radiation unit configured to emit a irradiation light to the image bearing member, a light receiving unit configured to receive a reflected light from the measurement image formed on the image bearing member
Data Source
AI summary
An image forming apparatus includes an image bearing member, a controller controls a first and the second image forming unit to form a measurement image on the image bearing member, wherein the measurement image is composed with a first measurement image having a first color, and a second measurement image having a second color with a lower reflectance than the first color, a radiation unit emits a irradiation light to the measurement image, a light receiving unit receives a reflected light from the measurement image, a comparison unit compares a light amount of the reflected light from the measurement image with a threshold value, and a changing unit increases the threshold value, if a measurement time period during which a light amount of the reflected light from the measurement image is equal to or greater than the threshold value is longer than a predetermined time period.