Exposure Means Pre-Exposure Control for Negative Ghost Prevention
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Solution Overview
Problem
In electrophotographic image forming apparatuses, the generation of negative ghosts due to remaining photo-carriers can occur, leading to image quality issues. Existing solutions, such as pre-exposure methods, require additional components, increasing the size and cost of the apparatus.
Innovation Solution
An image forming apparatus with a controller that determines whether to execute a pre-exposure based on the standing time since the last image forming operation and the stored information about the charge generation layer thickness, allowing the exposure means to perform pre-exposure if necessary.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a separate pre-exposure means is provided to prevent negative ghost, then negative ghost is prevented, but the size and cost of the image forming apparatus increases
Solution Approach 1:
The exposure means is designed to perform dual functions: normal image formation during active operation and pre-exposure when idle time exceeds the threshold. This eliminates the need for a separate pre-exposure device while maintaining negative ghost prevention capability.
Solution Approach 2:
The exposure means serves itself by performing pre-exposure function when the apparatus is idle for extended periods. The control unit automatically activates this self-service mode based on idle time detection, preventing negative ghost without external intervention or additional components.
2Reliability
If pre-exposure is always executed to prevent negative ghost, then image quality is improved, but productivity decreases due to additional exposure time
Solution Approach 1:
The pre-exposure execution is made dynamic rather than static. The control unit continuously monitors idle time and dynamically adjusts whether to execute pre-exposure based on whether the idle time exceeds a predetermined threshold, optimizing both image quality and productivity.
Solution Approach 2:
Pre-exposure is performed periodically based on idle time cycles rather than continuously. The system checks idle time intervals and executes pre-exposure only when necessary (when idle time exceeds threshold), creating a periodic action pattern that balances image quality with productivity.
3Reliability
If the photosensitive member is exposed to light before image formation using the exposure means, then negative ghost is prevented, but the first print out time increases
Solution Approach 1:
Pre-exposure is performed as a preliminary action during idle periods before actual image formation begins. By executing pre-exposure during naturally occurring idle time (when no image formation is scheduled), the system prepares the photosensitive member in advance without adding to the critical first print out time.
Solution Approach 2:
The system recovers idle time that would otherwise be wasted and utilizes it for pre-exposure purposes. Instead of treating idle time as lost time, the system discards the idle state and recovers it by performing pre-exposure, thereby preventing negative ghost without impacting productive time.
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 effectively prevents negative ghost generation by optimizing the pre-exposure process, thereby improving image quality without increasing the apparatus's size or cost.
Implementation Method 1
exposure means for forming an electrostatic latent image on a surface of the image bearing member by exposing the image bearing member to light
Implementation Method 2
developing means including a developer carrying member for carrying a developer and configured to develop the electrostatic latent image by supplying the developer
Data Source
AI summary
An image forming apparatus includes an image bearing member, an exposure portion, a developing portion including a developer carrying member, a transfer portion, a development separation portion, a transfer separation portion, a storing portion, and a controller. Before a present image forming operation, the controller controls the transfer separation portion to put the image bearing member and the transfer portion in a separation state and controls the development separation portion to put the image bearing member and the developer carrying member in a separation state, and then the controller carries out control to determine whether or not pre-exposure for exposing the image bearing member to light by the exposure portion is executed, depending on a standing time from an end of a last image forming operation to a start of the present image forming operation and on information stored in the storing portion.