Motor Back Tension Control via Counter-EMF
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Solution Overview
Problem
Existing image forming apparatuses face complexity and high costs in configuring and controlling back tension to prevent skewed paper conveyance, particularly due to the use of electromagnetic or powder clutches.
Innovation Solution
An image forming apparatus with a motor and rotation transmission mechanism that creates counter-electromotive force by being shorted or operating at less than minimum driving voltage, coupled with a conveyance speed control unit to adjust back tension based on detected print medium information, allowing for simple configuration and control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electromagnetic clutch or powder clutch is used to control back tension, then back tension control is achieved, but device complexity and cost increase
Solution Approach 1:
The patent replaces electromagnetic clutch or powder clutch with a motor that operates in electrically shorted state or at voltage below minimum driving voltage. This substitution eliminates complex clutch mechanisms while achieving the same back tension control function through motor's electromagnetic resistance特性, thereby reducing device complexity and cost while maintaining reliable back tension control
Solution Approach 2:
The patent uses a motor in a non-driving state (electrically shorted or below minimum voltage) as a simple, cost-effective alternative to expensive electromagnetic or powder clutches. The motor's inherent electromagnetic properties are exploited for back tension control without requiring additional clutch components, reducing overall system cost and complexity
2Reliability
If electromagnetic clutch or powder clutch is used to control back tension, then back tension control is achieved, but control complexity increases
Solution Approach 1:
The patent replaces the complex control mechanisms of electromagnetic or powder clutches with simple motor voltage control. By operating the motor in electrically shorted state or at voltage below minimum driving voltage, the system achieves back tension control through the motor's electromagnetic resistance特性, eliminating the need for complex clutch control circuits and simplifying the overall control architecture
Solution Approach 2:
The patent makes the motor serve multiple functions: it can operate as a drive motor during normal operation and as a back tension control device when operated in electrically shorted state or below minimum driving voltage. This multi-functionality eliminates the need for separate clutch components and their associated control mechanisms, thereby simplifying the control system
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 straightforward adjustment of back tension and effective correction of skewed conveyance with reduced complexity and cost, ensuring proper paper conveyance and image formation.
Implementation Method 1
a unit configured to cause the motor to be in a state where the motor creates a counter-electromotive force when rotational force from the roll body is received, by causing the motor to be in an electrically shorted state or by applying a voltage less than a minimum driving voltage to the motor
Data Source
AI summary
A load applying unit includes a motor and a rotation transmission mechanism.A unit for causing the motor to be in a state where the motor creates a counter-electromotive force when rotational force from the roll body is received by applying a voltage less than a minimum driving voltage to the motor and a unit for changing a conveyance speed with which the conveyance unit conveys the print medium are included. While the print medium is pulled out from the roll body and the print medium is set in a state where image forming can be started, the motor is caused to be in the state where the motor can create the counter-electromotive force, and the conveyance unit performs a conveyance operation by changing the conveyance speed of the print medium in accordance with a detection result of the detecting unit.