Moving-Member Speed Detection Using Cross-Correlation Imaging
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Solution Overview
Problem
Existing moving-member detecting devices in color image forming apparatuses face challenges in accurately measuring the speed of moving members like intermediate transfer belts due to measurement errors caused by changes in temperature or detecting distance, leading to potential color registration errors.
Innovation Solution
A moving-member detecting device that includes an image acquiring unit with a light source and area sensors to capture two-dimensional images at different positions along the moving member's path, using cross-correlation operations to calculate the moving speed, thereby minimizing measurement errors from temperature or distance changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If speed is calculated from displacement in a small section using pixel size of camera, then speed can be detected, but measurement precision deteriorates due to discretization error and integration error
Solution Approach 1:
The patent transitions from one-dimensional pixel-based speed calculation to two-dimensional image-based speed calculation. By capturing images at two different positions along the moving direction and calculating displacement in the image plane, the system achieves higher measurement precision while maintaining ease of operation. The image acquiring unit captures images at position 1 and position 2, and the speed calculating unit computes speed from the two-dimensional image data rather than one-dimensional pixel displacement.
2Device complexity
If imaging magnification changes due to temperature characteristics or detecting distance change, then the detecting system remains simple, but measurement precision deteriorates due to speed measurement error
Solution Approach 1:
The patent incorporates feedback by acquiring images at two different positions along the moving direction and using this information to calculate actual speed. The speed calculating unit computes the moving speed based on the displacement observed in the two images, creating a feedback mechanism that compensates for magnification changes. This feedback approach maintains device simplicity while improving measurement precision by using actual observed displacement rather than relying on fixed magnification assumptions.
3Ease of operation
If belt conveyance position is calculated by integrating speed, then position can be determined, but measurement precision deteriorates due to error integration
Solution Approach 1:
The patent applies preliminary action by acquiring images at two predetermined positions before performing speed calculation. The image acquiring unit is configured to acquire images at position 1 and position 2 in advance, and the speed calculating unit uses these pre-acquired images to calculate speed. This preliminary acquisition of data at known positions eliminates the need for continuous integration, thereby preventing error accumulation while maintaining position calculation capability.
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 high-accuracy speed measurement of moving members, reducing color registration errors and ensuring precise belt conveyance control, even under varying environmental conditions.
Implementation Method 1
a light source configured to emit a light beam to a detecting position of a moving member
Data Source
AI summary
A moving-member detecting device includes an image acquiring unit and a speed calculating unit. The image acquiring unit includes a light source configured to emit a light beam to a detecting position of a moving member; an area sensor configured to acquire image data of a one- or two-dimensional image; and an area-sensor control unit configured to acquire the image data. The image acquiring unit is configured to acquire pieces of image data of the moving member at first and second positions, respectively, in a moving direction of the moving member so as to acquire the piece of position image data for the second position when the moving member is at the second position after acquiring the piece of image data for the first position. The speed calculating unit is configured to calculate a moving speed of the moving member from the pieces of image data.