Belt Driving Device Reference Timing Control
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Solution Overview
Problem
Existing image forming apparatuses face color shift issues due to errors in determining the reference timing when image carriers or opposing members contact or separate from the belt member, leading to unstable belt speed and increased costs from using home position sensors.
Innovation Solution
A belt driving device that detects the driving speed and rotational angular displacement of the belt member using encoders, determines the reference timing based on the speed variation pattern, and adjusts the driving speed to prevent color shift without a home position sensor, by using the reference timing from a previous rotation during contact-state-changing events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a home position sensor is used to determine reference timing, then the reference timing can be accurately detected, but the device complexity and cost increase
Solution Approach 1:
The patent extracts the reference timing detection function from the home position sensor and relocates it to the encoder system. By analyzing the speed variation pattern from encoder pulses, the system determines reference timing without requiring a separate home position sensor, thereby reducing device complexity while maintaining measurement precision
Solution Approach 2:
The encoder is given a dual function: it not only detects belt speed for basic control but also determines reference timing by analyzing speed variation patterns. This multi-functionality eliminates the need for a dedicated home position sensor, resolving the contradiction between measurement precision and device complexity
2Loss of time
If reference timing is determined during contact-state-changing rotation, then the latest timing information is obtained, but the reference timing becomes inaccurate due to load changes
Solution Approach 1:
The system performs preliminary action by determining reference timing in the rotation before the contact-state-changing rotation, when load conditions are stable. This prevents the load changes during contact-state-changing rotation from affecting reference timing accuracy, while still providing timely control for the subsequent rotation
Solution Approach 2:
The patent cushions against the harmful effect of load changes by proactively determining reference timing before the contact-state-changing rotation occurs. This beforehand cushioning ensures that the reference timing is established under stable conditions, preventing future timing errors without delaying the control response
3Object-affected harmful factors
If belt speed is adjusted to cancel speed variation, then color shift is prevented, but the control system becomes more complex
Solution Approach 1:
The system implements feedback control by detecting the actual belt speed through encoder pulses, comparing it with the target speed, and adjusting the driving motor speed accordingly. The speed variation pattern is detected and used to generate compensatory control signals, creating a closed-loop feedback system that prevents color shift while maintaining manageable control complexity
Solution Approach 2:
The patent replaces complex mechanical timing mechanisms with an electronic control system that uses encoder feedback and computational algorithms to achieve the same color shift prevention function. This substitution simplifies the overall system by using electronic sensing and control rather than mechanical timing devices
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 stabilizes the belt speed and prevents color shift by using the reference timing from a previous rotation, reducing the need for costly home position sensors and improving the accuracy of belt speed control during contact-state changes.
Implementation Method 1
a second detecting unit configured to detect rotational angular displacement or a rotational angular speed of the subordinate rotary body
Implementation Method 2
A belt member that has been manufactured by a centrifugal molding technique is likely to have an inconsistent thickness due to the eccentricity of the die
Implementation Method 3
The speed variation during one rotation of the belt depicts a sine curve corresponding to one period
Implementation Method 4
The driving speed of the driving motor which is the driving source of the driving roller is adjusted so that the driving speed has an opposite phase to that of the waveform of the speed variation pattern
Implementation Method 5
drive the belt at various speeds in such a manner as to cancel out the speed variation caused by the belt thickness inconsistency
Data Source
AI summary
In an image forming apparatus, during a rotation of an intermediate transfer belt performed after a contact-state-changing rotation in which the number of photoconductors contacting the intermediate transfer belt has changed, a control unit of a belt driving device controls the driving speed of a belt driving motor based on a period of the intermediate transfer belt determined in the rotation immediately before the contact-state-changing rotation instead of a period determined in the contact-state-changing rotation.