Polygon Mirror Phase Control via Non-Image Light Irradiation

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Solution Overview

Problem

Conventional image forming apparatuses require separate activation control and phase control for rotational polygon mirrors, increasing the time needed to reach the target rotation speed and start image formation.

Innovation Solution

An image forming apparatus with a control unit that simultaneously controls the rotation speeds and phases of multiple rotational polygon mirrors by irradiating non-image regions with light, allowing for independent speed control and phase synchronization, thereby reducing the activation time.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If separate activation control and phase control are performed for rotational polygon mirrors, then rotation speed and phase can be controlled independently, but the time required to reach target speed and start image formation increases

Engineering Contradiction:

Improverotation speed control stabilityVSAvoidactivation time

Core Design Contradiction:

ReliabilityVSLoss of time

Solution Approach 1:

The patent combines activation control and phase control into a single integrated control process. The control unit simultaneously manages both rotation speed and phase alignment by coordinating light source activation with polygon mirror rotation, allowing both control objectives to be achieved concurrently rather than sequentially, thereby reducing total activation time while maintaining control stability

Inventive Principle:

Principle #5Merging (Combining)

2Speed

If light is irradiated to non-image regions for detection during acceleration, then rotation speed can be controlled, but the photosensitive drum may be exposed to unnecessary laser light

Engineering Contradiction:

Improverotation speedVSAvoidunnecessary light exposure

Core Design Contradiction:

SpeedVSObject-affected harmful factors

Solution Approach 1:

The control unit employs periodic light irradiation to non-image regions during the acceleration phase. Light is irradiated in controlled periods rather than continuously, allowing the detection unit to capture rotation position information at specific intervals. This periodic approach enables rotation speed control while minimizing the total duration of light exposure to the photosensitive drum, reducing unnecessary light exposure

Inventive Principle:

Principle #19Periodic action

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 approach shortens the time required to initiate image formation by concurrently managing rotation speed and phase control, ensuring stable detection of scanning signals and minimizing exposure of the photosensitive drum to unnecessary laser light.

Implementation Method 1

a rotational polygon mirror having a plurality of reflecting surfaces and configured to deflect light emitted from the light source while rotating

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 2

a detection unit configured to detect the light deflected by the rotational polygon mirror

Methodology Applied

Scientific EffectLight detection: Photoelectric Effect

Data Source

PatentUS10705448B2Image forming apparatus performing phase control of rotational polygon mirror

Publication Date: 2020.07.07 CANON KK

AI summary

In a case of performing a second rotation control to match the rotation phase of a first rotational polygon mirror with the rotation phase of a second rotational polygon mirror in a rising period, a period during which a non-image region is irradiated with light from both or one of a first light source and a second light source is controlled to be a second period longer than a first period.