Semiconductor Laser Correction Current for Image Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Semiconductor lasers in electrophotographic image forming apparatuses exhibit light emission delay characteristics, leading to insufficient light exposure and image density issues due to the conventional method's inability to adequately correct light emission delays with fixed peak correction currents.
Innovation Solution
The image forming apparatus includes a semiconductor laser, a driving current supply unit, and a correction current supply unit that adjusts the driving current based on real-time light reception results, using multiple correction current generation units to attenuate the correction current over time, ensuring accurate light amount correction even with multiple light emission delay components.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a fixed peak value correction current is used, then the light emission delay is corrected for a specific driving current value, but the correction becomes insufficient when the driving current value changes
Solution Approach 1:
The correction current peak value is made variable rather than fixed. The correction current generation unit dynamically adjusts the peak value based on the actual driving current value supplied to the semiconductor laser, enabling accurate light amount correction across different operating conditions and driving current levels.
Solution Approach 2:
The system uses feedback from the light receiving unit (photodiode) that detects the actual light output of the semiconductor laser. This feedback information is used to adjust the correction current peak value, creating a closed-loop control system that maintains accurate light amount correction despite changes in driving current value or laser characteristics.
2Illumination intensity
If the driving current is increased to compensate for light emission delay, then the light amount becomes sufficient, but the light emission delay characteristics cause the light amount to exceed the target during the rising phase
Solution Approach 1:
A correction current is supplied in advance at the rising phase of the driving current to compensate for the anticipated light emission delay. This preliminary action ensures that the light amount reaches the target value timely, while the correction current is designed to attenuate appropriately to prevent overshoot.
Solution Approach 2:
The correction current waveform parameters (peak value, attenuation rate) are adjusted based on the driving current value. By changing these parameters dynamically, the system achieves precise light amount control during the rising phase without causing overshoot, while still compensating for the light emission delay.
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 insufficient light exposure and low image density by synchronizing the correction currents with the driving current, allowing for precise light amount adjustment and improved image quality.
Implementation Method 1
a light receiving unit configured to receive the laser beam emitted from the semiconductor laser
Data Source
AI summary
An image forming apparatus is provided for controlling current(s) supplied to a semiconductor laser. In one or more embodiments, an image forming apparatus corrects a value of the driving current and a value of at least one correction current (e.g., first and/or second correction current(s)) supplied in synchronization with the supply start of the driving current based on a reception result of a light receiving unit. In one or more embodiments, an image forming apparatus includes a correction current supply unit including a first correction current generation unit for generating a first correction current that attenuates over time and a second correction current generation unit for generating a second correction current that attenuates over time and of which an attenuation speed is lower than that of the first correction current, and configured to supply the first correction current and the second correction current to the semiconductor laser.