Image Forming Motor Control for Precise Transfer Gap Positioning

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Solution Overview

Problem

Existing motor control methods in image forming apparatuses, such as those described in United States Patent Application Publication No. 2017/0288590, fail to precisely adjust the distance between rotating members, leading to potential image formation failures due to power consumption increases and motor noise, especially when switching from vector control to constant current control.

Innovation Solution

An image forming apparatus with a controller that switches between constant current control and vector control based on rotor speed, using a phase determiner to accurately assess the rotation phase of the motor and adjust control modes to prevent power consumption increases and ensure precise image formation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the motor control is switched from vector control to constant current control when the instruction speed decreases, then the power consumption is reduced, but the rotation phase of the rotor becomes ahead of the target phase causing imprecise adjustment of rotating member distances

Engineering Contradiction:

Improvepower consumptionVSAvoidadjustment precision of rotating member distances

Core Design Contradiction:

Use of energy by moving objectVSManufacturing precision

Solution Approach 1:

The patent implements feedback control by continuously monitoring the rotation phase of the rotor and comparing it with the target phase. When the rotation phase becomes ahead of the target phase during constant current control, the system detects this deviation and adjusts the control strategy accordingly, ensuring precise positioning while maintaining low power consumption.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent dynamically switches between vector control and constant current control based on the instruction speed and rotation phase conditions. This dynamic control strategy allows the system to optimize power consumption during low-speed operation while maintaining positioning precision through timely switching back to vector control when phase deviation occurs.

Inventive Principle:

Principle #15Dynamics

2Object-affected harmful factors

If the motor control is switched from vector control to constant current control, then the motor noise is reduced, but the rotor may go out of synchronization with input signals causing step-out state

Engineering Contradiction:

Improvemotor noiseVSAvoidsynchronization between rotor and input signals

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

The system continuously monitors the rotation phase and compares it with the target phase to detect synchronization deviations. When the rotor phase becomes ahead of the target phase or step-out is detected, the feedback mechanism triggers a switch back to vector control, preventing loss of synchronization and maintaining reliable operation.

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent performs preliminary checks on the rotation phase before allowing constant current control to continue. By detecting phase deviation in advance and switching control modes proactively, the system prevents step-out conditions from occurring, ensuring continuous reliable operation.

Inventive Principle:

Principle #10Preliminary action

3Manufacturing precision

If the instruction speed is set to decrease gradually, then the rotation phase can follow the target phase more closely, but the overall processing time increases

Engineering Contradiction:

Improverotation phase alignmentVSAvoidprocessing time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent dynamically adjusts the instruction speed profile based on the current control mode and phase alignment status. During vector control, faster speed changes are permitted, while during constant current control, the system automatically reduces instruction speed to maintain phase alignment. This dynamic adjustment optimizes both precision and processing time.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The system changes the instruction speed parameter adaptively based on the control mode and phase deviation. When switching to constant current control, the instruction speed is automatically reduced to a lower value to ensure the rotor can follow the target phase. This parameter change allows the system to achieve precise positioning without excessive processing time.

Inventive Principle:

Principle #35Parameter changes

Data Source

PatentUS11843341B2Image forming apparatus having reduced power consumption

Publication Date: 2023.12.12 CANON KK

AI summary

An image forming apparatus includes a photosensitive member, an intermediate transfer member, a moving member, a driving motor, a stepper motor, a detector, a phase determiner, and a controller. The stepper motor drives the moving member to move between a first position at which the photosensitive member contacts the intermediate transfer member and a second position at which the photosensitive member contacts the intermediate transfer member are separated. The controller includes a first control mode to control a motor based on a predetermined current magnitude and a second control mode to control a motor by vector control. The controller starts driving the driving motor in the first control mode, and then switches from the first control mode to the second control mode. The controller controls the stepper motor in the first control mode during a period from when the stepper motor is activated to when the stepper motor is stopped.