Ink Ejection Timing Control for Belt Speed Fluctuation
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Solution Overview
Problem
Current image forming apparatuses face high costs and inaccuracies in adjusting transportation movement amounts due to the need for multiple encoders or high-resolution encoders, and speed fluctuations in the transportation belt lead to errors in ink ejection timing, resulting in low image quality.
Innovation Solution
An image forming apparatus with a transportation belt and an ejection timing control unit that adjusts ink ejection timing based on the number of ejection timings, distance between flushing openings, and print resolution, using a combination of encoder output signals to correct for speed fluctuations, thereby eliminating the need for high-resolution encoders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high resolution encoders or multiple encoders are installed to accurately adjust transportation movement amount, then measurement precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts the speed fluctuation detection function from the encoder system by using the flushing opening part as a reference marker. Instead of relying on high-resolution encoders to detect every position, the system only needs to detect when the flushing opening passes a fixed sensor point, simplifying the measurement system while maintaining accuracy for timing correction purposes.
Solution Approach 2:
The flushing opening part serves as an intermediary reference element between the transportation belt and the sensor. By detecting the passage of this known reference feature, the system can calculate belt speed fluctuations without requiring direct high-precision measurement of every position on the belt, thus reducing encoder requirements.
2Speed
If rotary encoder is used to detect motor or roller rotation, then transportation speed detection is enabled, but speed fluctuation errors are not detected and accumulate over time
Solution Approach 1:
The system implements feedback by continuously monitoring the actual passage time of the flushing opening and comparing it against expected timing. This feedback mechanism detects speed fluctuations in real-time and enables correction of ink ejection timing to compensate for transportation variations, preventing error accumulation.
Solution Approach 2:
The flushing opening passes the sensor periodically, creating regular measurement opportunities to detect speed fluctuations. This periodic detection allows the system to continuously update timing corrections at known intervals, maintaining accurate ink ejection timing despite variations in belt speed during operation.
3Device complexity
If transportation belt speed fluctuates due to driving system issues, then device complexity is reduced, but manufacturing precision deteriorates
Solution Approach 1:
The system transitions from static timing assumptions to dynamic timing adjustment. By continuously measuring the actual passage time of the flushing opening and calculating speed fluctuations, the system dynamically adjusts ink ejection timing to compensate for transportation variations, maintaining precision despite simple driving system fluctuations.
Solution Approach 2:
The system changes the timing parameter for ink ejection based on detected transportation speed fluctuations. By calculating the deviation from expected flushing timing and applying corrective offset to ink ejection timing, the system maintains image formation precision without requiring a complex rigid driving system.
Data Source
AI summary
An image forming apparatus includes a transportation belt, a print engine, and an ejection timing control unit. The transportation belt transports a print sheet. The print engine ejects ink onto the print sheet. The ejection timing control unit adjusts an ink ejection timing of the print engine. The transportation belt includes a flushing opening part. The print engine repeatedly performs ink flushing to the flushing opening part at predetermined timings. Further the ejection timing control unit derives an adjustment amount for the ink ejection timing of the print engine on the basis of: a number of the ink ejection timings in a period from a previous flushing time to a current flushing time, a distance from the flushing opening part for the flushing at the previous flushing time to the flushing opening part for the flushing at the current flushing time, and a print resolution.