Scanning Motor Startup Control via Off-Image Beam Detection
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Solution Overview
Problem
Existing image forming apparatuses face challenges in preventing developer adhesion to the image bearing member during startup, leading to increased output time for the first print when forcibly accelerating the scanning motor.
Innovation Solution
An image forming apparatus with a control system that emits a light beam outside the image region of the image bearing member during startup, allowing the developing member to contact the image bearing member without adhesion issues, and includes a control portion to manage the light source emission, drive operation of the rotating polygon mirror, and movement of the developing member.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the laser is forcibly emitted to the image region of the photosensitive drum during startup, then the number of rotations of the scanning motor can be detected, but the developer adheres to the photosensitive drum causing increased output time for the first print
Solution Approach 1:
The patent introduces an intermediary detection region positioned between the image region and the laser emission path. A beam sensor detects the laser beam in this intermediary region, allowing indirect measurement of the scanning motor's rotation without the laser directly irradiating the image-bearing surface. This mediator approach enables rotation detection while preventing developer adhesion on the photosensitive drum.
Solution Approach 2:
The patent extracts the laser beam detection function from the image region and relocates it to a separate intermediary region. By separating the detection function from the image formation surface, the system can monitor scanning motor rotation without exposing the photosensitive drum to laser radiation that would cause developer adhesion.
2Speed
If the scanning motor is forcibly accelerated for startup, then the rotation speed is quickly achieved, but the developing member cannot contact the image bearing member without causing developer adhesion
Solution Approach 1:
The patent uses an intermediary laser beam detection region that allows the scanning motor to be accelerated to operational speed while the developing member remains separated. The beam sensor in the intermediary region provides rotation feedback without requiring the developing member to contact the drum during the acceleration phase, thus preventing developer adhesion.
Solution Approach 2:
The patent performs preliminary acceleration of the scanning motor using the intermediary detection method before the developing member is brought into contact with the image bearing member. This preliminary action allows the motor to reach steady rotation speed in advance, ensuring proper scanning operation when the developing member subsequently contacts the drum without developer adhesion issues.
3Object-generated harmful factors
If the laser emission is controlled to avoid the image region during startup, then developer adhesion is prevented, but the detection of scanning motor rotation becomes more complex
Solution Approach 1:
The patent segments the laser path into distinct regions: an intermediary detection region for beam sensing and an image region for actual image formation. This spatial segmentation allows independent control of detection and image formation functions, simplifying the overall control logic despite the additional spatial dimension.
Solution Approach 2:
The laser beam serves multiple functions: it acts as both the imaging tool for image formation and as a measurement tool for detecting scanning motor rotation through the intermediary beam sensor. This multi-functionality reduces the need for separate detection systems, thereby limiting the increase in device complexity.
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 the developing member to contact the image bearing member without developer adhesion, reducing the output time of the first print by controlling the light source emission and developing member movement in conjunction with the rotating polygon mirror's startup.
Implementation Method 1
a light source configured to emit a light beam
Implementation Method 2
a rotating polygon mirror configured to reflect the light beam emitted from the light source
Data Source
AI summary
An image forming apparatus: includes a developing member to be movable between a development position where the developing member contacts an image bearing member and a separated position where the developing member is separated from the image bearing member; and a control portion controls the number of rotations of a drive portion by causing a light source to emit a light beam when a rotating polygon mirror starts to rotate, and detecting the light beam emitted from the light source by a detecting portion, wherein when the rotating polygon mirror starts to rotate, the light beam does not enter an image region of the image bearing member and the light beam is detected outside the image region of the image bearing member by the detecting portion, in a state of the developing member having moved from the separating position to the development position.