Photosensitive Drum Charging Sequence for Uniform Image Formation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing image forming apparatuses using combined charge injection and contact charging methods face issues with discharge products and surface alteration of the photosensitive drum, particularly in high-temperature and high-humidity environments, leading to charging non-uniformity and image defects.
Innovation Solution
An image forming apparatus with a first charging member for injection charging and a second charging member for discharge charging, controlled to apply only DC voltages, where the second charging voltage exceeds the discharge threshold during rotation, ensuring uniform charging and minimizing discharge products.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If contact charging method using discharge is used, then charging stability is improved, but discharge products are generated and photosensitive drum surface is altered
Solution Approach 1:
The charging process is divided into two distinct stages: a first charging stage using charge injection method (without discharge) to establish initial potential, and a second charging stage using contact charging method (with discharge) to refine and uniform the potential distribution. This segmentation allows each method to contribute its advantages while minimizing its disadvantages.
Solution Approach 2:
The charge injection method is applied first as a preliminary action to establish an initial potential distribution on the photosensitive drum surface before the contact charging method is applied. This preliminary charging reduces the subsequent discharge intensity and minimizes the generation of discharge products.
2Object-generated harmful factors
If charge injection method is used, then discharge products are suppressed, but charge uniformity is insufficient
Solution Approach 1:
The charging process is divided into two distinct stages: a first charging stage using charge injection method (without discharge) to establish initial potential, and a second charging stage using contact charging method (with discharge) to refine and uniform the potential distribution. This segmentation allows each method to contribute its advantages while minimizing its disadvantages.
Solution Approach 2:
The first charging stage acts as an intermediary that prepares the photosensitive drum surface by establishing an initial potential distribution, which then serves as a foundation for the second charging stage to achieve uniform potential distribution through controlled discharge.
3Manufacturing precision
If combined charging methods are used, then charge uniformity is improved, but discharge products increase at startup
Solution Approach 1:
The charge injection method is applied first as a preliminary action to establish an initial potential distribution on the photosensitive drum surface before the contact charging method is applied. This preliminary charging reduces the subsequent discharge intensity and minimizes the generation of discharge products.
Solution Approach 2:
The control unit dynamically adjusts the charging voltage parameters based on the operational state. During normal operation, the second charging voltage is set to achieve uniform potential distribution. At startup, the system uses the preliminary charge injection to reduce the discharge intensity when the second charging method is applied.
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 configuration suppresses adverse effects from discharge, maintaining stable and uniform charging, reducing discharge products, and preventing image smearing, thereby ensuring high-quality image formation.
Implementation Method 1
a first charging member configured to oppose the photosensitive drum to form a first charging portion, and to charge a surface of the photosensitive drum at the first charging portion in response to application of a first charging voltage thereto
Implementation Method 2
a second charging member configured to oppose the photosensitive drum, in a position downstream of the first charging portion and upstream of the developing portion in a rotational direction of the photosensitive drum, to form a second charging portion, and to charge a surface of the photosensitive drum by discharge at the second charging portion in response to application of a second charging voltage of at least a discharge start threshold thereto
Data Source
AI summary
An image forming apparatus includes a drum, a first charger configured to charge at a first charging portion between the drum and the first charger in response to application of a first charging voltage, a developing roller configured to supply a developer to the drum at a developing portion, a second charger configured to form a second charging portion downstream of the first charging portion and upstream of the developing portion in drum rotation direction, and to charge by discharge at the second charging portion in response to application of a second charging voltage, and a controller configured to control voltage application, and the controller is configured to control such that the second charging voltage to start discharge is applied to the second charger during the rotation of the drum and after application of the first charging voltage.