Sheet Conveying Roller Speed Control for Delay and Jam Prevention
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Solution Overview
Problem
Existing image forming apparatuses face issues with sheet conveyance delays and misalignment due to slipping, leading to reduced productivity and potential sheet jams, especially during continuous printing jobs.
Innovation Solution
A sheet conveying device with a speed control unit that adjusts the conveying speed of rollers based on sheet detection, increasing speed when a delay is detected and returning to normal speed at a determined point to stabilize conveyance and prevent damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the conveying speed of the sheet is increased to reduce conveyance delays and improve productivity, then productivity is improved, but sheet damage and jams may occur due to excessive speed
Solution Approach 1:
The conveying speed is made dynamic rather than fixed. The speed control unit adjusts the conveying speed of the first conveying roller based on real-time detection of sheet spacing. When a following sheet is detected to be delayed, the speed is increased to catch up; when sheets are properly spaced, the speed is reduced to normal levels. This dynamic adjustment resolves the contradiction by allowing high speed only when necessary to maintain productivity while preventing sheet damage through speed reduction during normal operation.
Solution Approach 2:
A feedback control mechanism is implemented using a sheet sensor that continuously monitors the spacing between sheets. The sensor detects the leading edge and rear edge of sheets, and this detection information is fed back to the speed control unit. Based on the feedback about actual sheet spacing versus target spacing, the speed control unit adjusts the conveying speed accordingly. This closed-loop feedback system enables the system to automatically maintain optimal speed for productivity while preventing excessive speed that could cause sheet damage.
2Manufacturing precision
If the conveying speed is rapidly adjusted to correct sheet spacing delays, then sheet spacing precision is improved, but sheet damage may occur due to abrupt speed changes
Solution Approach 1:
The speed adjustment is made dynamic and adaptive rather than abrupt or fixed. The speed control unit calculates the required speed adjustment based on the detected spacing error and applies it progressively. This dynamic approach allows the system to achieve precise sheet spacing correction while avoiding abrupt speed changes that could damage sheets.
Solution Approach 2:
The system prepares for potential sheet damage by implementing protective measures before damage can occur. The speed control unit monitors sheet spacing continuously and anticipates when speed adjustment will be needed. By detecting spacing deviations early and making gradual speed adjustments rather than abrupt changes, the system cushions against the harmful effects of rapid acceleration or deceleration that could damage sheets.
3Reliability
If the conveying speed is reduced to prevent sheet damage, then sheet safety is improved, but productivity decreases due to slower conveyance
Solution Approach 1:
The conveying speed is made dynamic rather than uniformly reduced. The speed control unit adjusts the speed based on real-time sheet spacing conditions. When sheets are properly spaced, the speed is maintained at normal levels for high productivity. When spacing deviations are detected that could lead to damage or jams, the speed is temporarily reduced to prevent these issues. This dynamic speed adjustment resolves the contradiction by achieving sheet safety only when necessary while maintaining high productivity during normal operation.
Solution Approach 2:
A feedback control mechanism enables the system to maintain high speed for productivity while ensuring sheet safety through continuous monitoring. The sheet sensor provides real-time feedback about sheet spacing, and the speed control unit adjusts speed accordingly. This allows the system to operate at high speeds for maximum productivity while automatically reducing speed only when spacing conditions indicate a risk to sheet safety, thus resolving the contradiction between productivity and sheet safety.
Data Source
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AI summary
A sheet conveying device (10) includes: a first conveying roller (91A); a second conveying roller (92A); a sheet sensor (51); and a speed control unit (106) that controls a conveying speed of a sheet by each of the first conveying roller and the second conveying roller, the speed control unit being configured to change, where a leading edge of a second sheet has not been detected at a reference time point, the conveying speed by the first conveying roller from an initial speed to a high speed faster than the initial speed, maintain the conveying speed by the second conveying roller at the initial speed, determine return timing on the basis of a second elapsed amount, and return the conveying speed by the first conveying roller from the high speed to the initial speed at the determined return timing.