Laser Power Dynamic Range Adjustment for Electrophotographic Discharge
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Solution Overview
Problem
Conventional electrophotographic devices face issues with print artifacts such as ghost images and color shifts due to excessive electrostatic charge on the photoconductive surface, particularly after restarting, which can be mitigated by discharging the surface to a consistent level during power down sequences, but existing discharge methods require a light source positioned around the photoconductive surface, affecting the system's size and efficiency.
Innovation Solution
A method to adjust the dynamic range of a laser power source by calibrating it to operate within different power levels, using a laser driver circuit and controller to set bias and drive currents, allowing the laser beam to shift between imaging and non-imaging sections of the scan line, enabling effective discharge operations without the need for a light source positioned around the photoconductive surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a light source is positioned around the photoconductive surface for discharge operations, then the photoconductive surface can be discharged to a consistent level, but the system size increases and efficiency decreases
Solution Approach 1:
The laser source is designed to perform multiple functions: imaging operations and discharge operations. By adjusting the laser power output dynamically, the same laser source can operate at different power levels suitable for either writing images or discharging the photoconductive surface, eliminating the need for a separate light source for discharge operations.
Solution Approach 2:
The laser source's output power is dynamically adjusted based on the operational mode. During discharge operations, the laser power is increased to a higher range compared to imaging operations. This parameter change allows the laser source to effectively discharge the photoconductive surface while maintaining its primary imaging function.
2Manufacturing precision
If the laser power range is fixed for imaging operations, then imaging quality is maintained, but discharge operations cannot be effectively performed
Solution Approach 1:
The laser source's output power is made dynamic rather than fixed. The system can switch between different power ranges depending on the operational requirement - a lower power range for imaging operations to maintain image quality and a higher power range for discharge operations to effectively remove electrostatic charge from the photoconductive surface.
Solution Approach 2:
Before imaging operations, the system performs a discharge operation using the laser source at elevated power levels to clear any residual electrostatic charge from the photoconductive surface. This preliminary action ensures that the surface is in a neutral state before image writing begins, preventing artifacts.
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 allows for efficient discharge of the photoconductive surface, reducing print artifacts and optimizing the system's size and efficiency by shifting the laser power range suitable for both imaging and discharge operations, ensuring consistent output and improved print quality.
Implementation Method 1
a laser source for emitting a laser beam, a scanner for causing the laser beam to sweep along a scan line
Implementation Method 2
an imaging system forms a latent image by exposing select portions of an electrostatically charged photoconductive surface to laser light. Essentially, the density of the electrostatic charge on the photoconductive surface is altered in areas exposed to the laser beam
Data Source
AI summary
The dynamic range of an electrophotographic device may be shifted by calibrating a laser power of a laser source to operate within a first range of power levels during a laser power adjustment operation. At least one laser control parameter is modified after calibrating the laser power so that the laser source is operable within a second range of power levels different from the first range of power levels and a beam emitted by the laser source is controlled within the second range of power levels when the beam is directed towards an image area of a photoconductive surface.