Optical Control Apparatus for Laser Power Stability
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Solution Overview
Problem
Existing optical control apparatuses for semiconductor lasers face challenges in adjusting laser beam power quickly without causing light power overshoot or undershoot, particularly during startup or toner save modes.
Innovation Solution
The apparatus includes a semiconductor laser, a light power detecting device, a monitor voltage generating device, a reference voltage generating device, a current control device, and a pseudo voltage input device, which gradually adjusts the reference voltage to prevent power overshoot and undershoot by using a pseudo voltage input under specific conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the reference voltage is established immediately at the start of the semiconductor laser, then the light power adjustment speed is improved, but light power overshoot occurs during control
Solution Approach 1:
The patent applies preliminary action by setting an initial reference voltage to a predetermined value before the light power control begins. This initial reference voltage is set to prevent overshoot from occurring in the early stage of control, allowing the light power to be adjusted rapidly without causing instability. The reference voltage is then gradually changed from this initial value to the target value, ensuring both fast response and stable control throughout the adjustment process.
2Stability of the object's composition
If the reference voltage is increased extremely slowly to avoid light power overshoot, then light power stability is improved, but the time required for adjustment increases
Solution Approach 1:
The patent applies dynamics by making the reference voltage change in a stepwise manner rather than uniformly. The reference voltage is changed in multiple stages with different rates, allowing faster adjustment when the light power is far from the target value and slower adjustment when approaching the target value. This dynamic adjustment strategy reduces the total adjustment time while maintaining light power stability and preventing overshoot.
3Productivity
If the reference voltage is changed rapidly to reduce adjustment time, then productivity is improved, but light power undershoot occurs in toner save mode
Solution Approach 1:
The patent applies local quality by setting different initial reference voltages depending on the control mode. In normal mode, one initial reference voltage is used, while in toner save mode, a different initial reference voltage is used to prevent undershoot. This allows the system to optimize both adjustment speed and stability for each specific operating condition, improving overall productivity without sacrificing light power stability in any mode.
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 allows for rapid adjustment of laser beam power while preventing overshoot and undershoot, ensuring stable image formation in laser printers by maintaining the light power within a predetermined range.
Implementation Method 1
the light power of the laser beam is kept constant under the control over energizing current for a semiconductor laser by monitoring the light power of the laser beam from the semiconductor laser through the use of a photodetector
Data Source
AI summary
In an optical control apparatus, a semiconductor laser emits a laser beam having a power corresponding to an energizing current. A light power detecting device detects a light power of the laser beam. A monitor voltage generating device generates a monitor voltage set based on the light power. A reference voltage generating device generates a reference voltage set based on a target light power of the laser beam. A current control device controls the energizing current such that the monitor voltage approaches the reference voltage based on a deviation of the monitor voltage from the reference voltage. A pseudo voltage input device inputs a predetermined pseudo voltage to the current control device instead of the monitor voltage under a predetermined condition such that a variation range of the deviation lies within a predetermined range.