Electrophotographic Drum Voltage Control to Prevent Toner Blurring
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Solution Overview
Problem
In image forming apparatuses without a contact and separation mechanism between the developing roller and photosensitive drum, toner transfer to non-image forming areas occurs, leading to blurring and image defects due to rapid changes in surface potential of the photosensitive drum, which complicates maintaining a constant potential difference and laser light exposure control.
Innovation Solution
An image forming apparatus with controlled exposure and developing voltage management during non-image formation, where the surface potential of the photosensitive drum is gradually adjusted in steps to maintain a predetermined potential difference and stable laser light exposure, using a control portion to manage the emission of laser light and developing voltage to prevent toner transfer to non-image areas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a contact and separation mechanism between the developing roller and photosensitive drum is provided, then blurring is prevented, but the device becomes more complicated and larger in size
Solution Approach 1:
The invention extracts and removes the contact and separation mechanism from the developing unit, achieving downsizing and simplification. Instead of using mechanical contact separation to prevent blurring, the patent applies a different approach by controlling the potential difference between the photosensitive drum and developing roller through voltage control, thereby eliminating the need for the problematic mechanical mechanism while preventing blurring through electrical control.
Solution Approach 2:
The invention changes the control parameter from mechanical contact/separation to electrical potential difference control. By dynamically adjusting the voltage applied to the developing roller relative to the photosensitive drum, the system maintains optimal toner adhesion conditions without physical contact changes, thus preventing blurring while avoiding mechanical complexity.
2Device complexity
If the developing roller and photosensitive drum are in constant contact, then the device is simplified and downsized, but toner transfer to non-image forming areas occurs causing blurring
Solution Approach 1:
The invention maintains constant mechanical contact between the developing roller and photosensitive drum for simplification, but dynamically changes the electrical parameter (potential difference) to prevent blurring. By controlling the voltage applied to the developing roller to maintain an appropriate potential difference relative to the photosensitive drum surface, the system prevents unwanted toner transfer while keeping the mechanical structure simple and compact.
Solution Approach 2:
The system employs feedback control by monitoring the potential difference between the photosensitive drum and developing roller, and dynamically adjusting the developing roller voltage accordingly. This feedback mechanism ensures that the potential difference remains within the optimal range to prevent toner transfer to non-image areas, thereby preventing blurring while maintaining constant contact.
3Object-affected harmful factors
If the surface potential of the photosensitive drum is rapidly changed during non-image formation, then toner transfer is prevented, but maintaining a constant potential difference becomes difficult
Solution Approach 1:
The invention implements feedback control by continuously monitoring the potential difference between the photosensitive drum and developing roller, and dynamically adjusting the developing roller voltage in response to changes in drum surface potential. This feedback mechanism ensures that the potential difference remains stable and within the optimal range, preventing toner transfer to non-image areas while maintaining compositional stability.
Solution Approach 2:
The system dynamically changes the voltage parameter applied to the developing roller in response to surface potential changes of the photosensitive drum. By adjusting the developing roller voltage to maintain a constant potential difference despite drum potential variations, the invention prevents toner transfer while maintaining stability in the electrical relationship between components.
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 effectively suppresses toner blurring by maintaining a stable potential difference and controlled laser light exposure, reducing image defects and toner consumption, while ensuring consistent image quality and motor control stability.
Implementation Method 1
an exposing unit configured to expose the surface of the photosensitive member charged by the charging member, the exposing unit including a light source configured to emit laser light to which the surface of the photosensitive member is exposed
Implementation Method 2
a detecting portion configured to detect the laser light and output a detecting signal
Implementation Method 3
a charging member configured to charge a surface of the photosensitive member; a charging voltage source configured to apply a charging voltage to the charging member
Implementation Method 4
a developing member configured to supply toner with normal polarity to the photosensitive member in a developing portion opposed to the photosensitive member and form a toner image; a developing voltage source configured to apply a developing voltage to the developing member
Data Source
AI summary
An image forming apparatus includes a photosensitive member, a charging member, an exposing unit to expose a surface of the photosensitive member, and a developing member to supply toner with normal polarity at a developing portion. A controller, during a non-image formation when a toner image is not formed on a surface of the photosensitive member, controls such that a developing voltage is changed in a predetermined voltage width by applying a first developing voltage while the area of the photosensitive member on which a first surface potential is formed passes through the developing portion and by applying a second developing potential of an opposite polarity side rather than the first developing voltage while the area of the photosensitive member on which a second surface potential is formed passes through the developing portion, and the controller controls such that the surface potential becomes a side of the normal polarity rather than the first developing voltage.