Laser Light Source Intensity Control for Image Formation

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The existing image forming apparatus experiences deviations in toner image formation positions between different colors due to changes in light intensity of the laser beam, which affects the density and consistency of the images produced, especially when printing speed varies with the heat capacity of the recording medium.

Innovation Solution

The image forming apparatus includes a processor that controls the light emission intensity of the laser light source to remain constant when the laser beam is incident on the photodetector, regardless of the rotation speed of the polygon mirror and photoconductor, ensuring consistent toner image formation across colors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If the light emission intensity of the laser beam is reduced to suppress toner image density changes when printing speed is slowed down, then the toner image density consistency is improved, but the time from when the laser beam is incident on the photodetector to when the photodetector outputs a signal changes, causing deviation in toner image formation positions between different colors

Engineering Contradiction:

Improvetoner image density consistencyVSAvoidtoner image formation position accuracy

Core Design Contradiction:

Manufacturing precisionVSMeasurement precision

Solution Approach 1:

The processor controls the laser light source to emit the laser beam at a predetermined timing based on the timing when the laser beam is detected by the photodetector, rather than reacting after the detection completes. This preliminary timing control ensures that the light emission intensity remains constant at the moment of detection, preventing position deviations while maintaining density consistency across different colors and printing speeds

Inventive Principle:

Principle #10Preliminary action

2Reliability

If the rotation speed of the polygon mirror and photoconductor is reduced to match the heat capacity of the recording medium, then the fixing time is optimized, but the time for the laser beam to be incident on the photoconductor becomes long, causing high toner image density

Engineering Contradiction:

Improvefixing time optimizationVSAvoidtoner image density control

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The system dynamically adjusts the light emission intensity of the laser beam based on the actual timing when the beam is detected by the photodetector. When printing speed is reduced and the laser beam incident time increases, the processor reduces the light emission intensity in real-time to maintain constant toner image density, while still allowing the rotation speeds to be optimized for fixing requirements

Inventive Principle:

Principle #15Dynamics

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 maintains consistent light emission intensity, preventing deviations in toner image formation positions between colors and ensuring uniform image density, thereby improving the overall printing quality and reliability.

Implementation Method 1

a photodetector configured to detect the laser beam reflected by the polygon mirror

Methodology Applied

Scientific EffectLight detection: Photoelectric Effect

Implementation Method 2

a polygon mirror positioned to reflect the laser beam while rotating and cause the laser beam to be incident on the photoconductor along a main scanning direction

Methodology Applied

Scientific EffectLight reflection: Reflection

Implementation Method 3

a laser light source configured to output a laser beam according to an image

Methodology Applied

Scientific EffectLaser emission: Laser

Implementation Method 4

The image forming apparatus irradiates a charged and rotating photoconductor with a laser beam from an exposure device based on an image to form an electrostatic latent image on the photoconductor

Methodology Applied

Scientific EffectPhotoconduction: Photoconductivity

Data Source

PatentUS11287760B1Image forming apparatus with variable light emission intentsity and computer-readable nonvolatile recording medium therefor

Publication Date: 2022.03.29 TOSHIBA TEC KK

AI summary

According to one embodiment, an image forming apparatus includes a rotatable photoconductor, a laser light source configured to output a laser beam according to an image, a polygon mirror positioned to reflect the laser beam while rotating and cause the laser beam to be incident on the photoconductor along a main scanning direction to form an electrostatic latent image, a photodetector configured to detect the laser beam reflected by the polygon mirror, a developer, a transfer mechanism, and a processor. The processor (a) controls the laser light source such that a light emission intensity of the laser light source is constant when the laser beam is incident on the photodetector, regardless of a rotation speed of the polygon mirror and (b) controls the output timing of the laser beam based on a detection result of the photodetector.