Fixing Unit Loop Control via Variable Motor Speed

Solution Overview

Problem

Conventional image forming apparatuses face challenges in stabilizing loop control of recording materials due to variations in the endurance states of fixing and conveying means, environmental conditions, and recording material types, leading to issues like paper wrinkles, image abrasions, and color drifts.

Innovation Solution

An image forming apparatus with a loop detection system, a motor control mechanism, and a used amount detection system that adjusts the rotation speed of the fixing unit based on the accumulative used amount of the fixing unit, ensuring stable loop control by varying the high and low speed settings of the motor according to the endurance and usage history of the fixing unit.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Length of moving object

If the recording material conveying speed of the fixing portion is increased, then the loop amount is decreased, but the recording material conveying speed may become faster than the transferring portion causing stretching and image quality deterioration

Engineering Contradiction:

Improveloop amountVSAvoidimage quality

Core Design Contradiction:

Length of moving objectVSReliability

Solution Approach 1:

The patent applies dynamics by making the motor rotation speed variable rather than fixed. The control unit dynamically adjusts the motor rotation speed based on real-time loop amount detection, allowing the fixing portion to operate at different speeds (high speed when loop is small, low speed when loop is large) to maintain optimal loop control without causing stretching or image quality deterioration.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback control by using a loop detection sensor to continuously monitor the loop amount and feeding this information back to the control unit. The control unit then adjusts the motor rotation speed based on the detected loop amount, creating a closed-loop control system that automatically maintains the loop within the desired range and prevents image quality issues.

Inventive Principle:

Principle #23Feedback

2Length of moving object

If the recording material conveying speed of the fixing portion is decreased, then the loop amount is increased, but the loop may become too large causing lack of space and rubbing of the unfixed image

Engineering Contradiction:

Improveloop amountVSAvoidimage rubbing

Core Design Contradiction:

Length of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent applies dynamics by making the motor rotation speed variable rather than fixed. The control unit dynamically adjusts the motor rotation speed based on real-time loop amount detection, allowing the fixing portion to operate at different speeds (high speed when loop is small, low speed when loop is large) to maintain optimal loop control without causing stretching or image quality deterioration.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback control by using a loop detection sensor to continuously monitor the loop amount and feeding this information back to the control unit. The control unit then adjusts the motor rotation speed based on the detected loop amount, creating a closed-loop control system that automatically maintains the loop within the desired range and prevents image quality issues.

Inventive Principle:

Principle #23Feedback

3Device complexity

If constant high and low speeds are used for the fixing portion, then the loop control is simple, but the recording material conveying speed varies with endurance causing unstable loop control

Engineering Contradiction:

Improvecontrol system complexityVSAvoidloop control stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The patent applies dynamics by making the motor rotation speed variable rather than fixed. The control unit dynamically adjusts the motor rotation speed based on real-time loop amount detection, allowing the fixing portion to operate at different speeds (high speed when loop is small, low speed when loop is large) to maintain optimal loop control without causing stretching or image quality deterioration.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent implements feedback control by using a loop detection sensor to continuously monitor the loop amount and feeding this information back to the control unit. The control unit then adjusts the motor rotation speed based on the detected loop amount, creating a closed-loop control system that automatically maintains the loop within the desired range and prevents image quality issues.

Inventive Principle:

Principle #23Feedback

Data Source

PatentUS7941063B2Image forming apparatus with loop control

Publication Date: 2011.05.10 CANON KK

AI summary

An image forming apparatus is provided, which prevents occurrence of conveying malfunction or image failure due to variation of conveying speed caused by endurance of a fixing unit or a conveying unit, variation of using environment, or a type of a recording material. The image forming apparatus includes: a fixing unit for heating and fixing a toner image on a recording sheet (P); a secondary transferring portion for conveying the recording sheet (P) to the fixing unit; a loop sensor for detecting a degree of a loop of the recording sheet (P) generated according to a speed difference between a conveying speed of the fixing unit and a conveying speed of the secondary transferring portion; a CPU for controlling the conveying speed of the fixing unit; a fixing deliver sensor for detecting a used amount of the fixing unit; and an EEPROM for storing information on the used amount of the fixing unit detected by the fixing deliver sensor. The CPU controls the conveying speed of the fixing unit based on the information of the used amount of the fixing unit stored in the EEPROM and a detection result of the loop sensor.