Variable Light Emission Control for Photosensitive Drum Stability
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Solution Overview
Problem
In image forming apparatuses, the surface potential of a photosensitive drum is difficult to control during the start-up period of a rotating polygon mirror, leading to potential deterioration due to inappropriate exposure timing and light emission amounts, especially when the mirror's speed is not yet stabilized.
Innovation Solution
An image forming apparatus with a control system that adjusts light emission amounts based on the rotational speed of the rotating polygon mirror, using a detecting portion to control light emission between image and non-image regions, ensuring appropriate exposure timing and minimizing drum deterioration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a laser beam is emitted to control surface potential of the photosensitive drum, then the surface potential can be appropriately controlled, but the photosensitive drum deteriorates due to excessive exposure
Solution Approach 1:
The patent applies dynamics by making the light emission amount variable based on the rotational speed of the polygon mirror. The control portion adjusts the light emission amount dynamically: when the mirror rotates at the prescribed speed, it emits light in a first amount for image formation; when rotating slower than prescribed speed, it emits light in a second (smaller) amount to prevent excessive exposure and drum deterioration while still controlling surface potential.
2Speed
If the rotating polygon mirror is accelerated to attain prescribed speed, then proper exposure timing can be achieved, but during acceleration the surface potential cannot be appropriately controlled due to speed variation
Solution Approach 1:
The patent implements feedback control by continuously monitoring the rotational speed of the polygon mirror and adjusting the light emission amount accordingly. The control portion receives feedback on whether the mirror is rotating at the prescribed speed and modifies the exposure parameters in real-time to maintain appropriate surface potential control throughout the acceleration period.
Solution Approach 2:
The patent applies parameter changes by varying the light emission amount based on the operational state of the polygon mirror. When the mirror speed is below the prescribed speed during acceleration, the system changes the light emission parameter from the first amount to the second (smaller) amount, ensuring proper surface potential control adapts to the changing speed conditions.
3Productivity
If the rotating polygon mirror rotates slower than prescribed speed, then the apparatus can operate during start-up period, but the exposure amount increases causing drum deterioration
Solution Approach 1:
The patent applies dynamics by making the light emission amount variable based on the rotational speed of the polygon mirror. The control portion adjusts the light emission amount dynamically: when the mirror rotates at the prescribed speed, it emits light in a first amount for image formation; when rotating slower than prescribed speed, it emits light in a second (smaller) amount to prevent excessive exposure and drum deterioration while still controlling surface potential.
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
The solution allows for precise control of exposure timing and light emission during the start-up period, reducing the risk of drum deterioration and ensuring stable surface potential, thereby improving the apparatus's performance and extending its lifespan.
Implementation Method 1
a rotating polygon mirror configured to reflect light irradiated from the irradiating portion and scan an image region and a non-image region on the photosensitive member
Implementation Method 2
laser scanning is performed by a scanning apparatus and an electrostatic latent image is formed on the photosensitive drum
Data Source
AI summary
When a photosensitive member and a developing portion are in a separation state and in a start-up period, a first light emission is performed in an image region and a non-image region. When light is detected at least twice during a period when the first light emission is being performed, a second light emission is performed in the non-image region. When a prescribed period of time has elapsed from the start of the second light emission, a third light emission is performed in the image region in a third light emission amount that is smaller than a second light emission amount during a period in which the photosensitive member makes at least one revolution. After the third light emission is performed, the photosensitive member and the developing portion are switched to a contact state.