Semiconductor Laser Current Control via Continuous Illumination
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Solution Overview
Problem
Existing image forming apparatuses face challenges in stabilizing the energization current for semiconductor lasers due to fluctuations in scan speed, which can lead to failures in detecting the laser beam and controlling the electric current effectively.
Innovation Solution
An image forming apparatus is designed with a semiconductor laser, a scanner unit, a light power detection unit, a current control unit, a home position detection unit, and a continuous illumination unit. The continuous illumination unit initiates continuous illumination of the semiconductor laser before the home position detection unit is expected to detect the laser beam, ensuring a stable current control regardless of scan speed fluctuations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the semiconductor laser is forcibly illuminated at timing corresponding to predetermined scan speed, then the BD signal detection timing can be adjusted, but the control time for energization current becomes insufficient when scan speed increases
Solution Approach 1:
The semiconductor laser is illuminated in advance before the BD signal detection timing to ensure that the control unit has sufficient time to adjust the energization current. This preliminary illumination allows the system to prepare the laser output level before actual detection occurs, resolving the time shortage issue when scan speed increases.
2Measurement precision
If continuous illumination is commenced at predetermined period before BD signal detection, then the laser beam amount can be adjusted, but the control stability deteriorates when scan speed fluctuates
Solution Approach 1:
The system uses the BD signal detection as feedback to dynamically adjust the continuous illumination period. When scan speed fluctuates, the detection timing changes, and the control unit automatically adjusts the illumination duration to maintain stable energization current control, ensuring both measurement precision and control stability.
3Ease of operation
If the BD sensor detects the laser beam immediately after initiation of continuous illumination, then the detection timing is simplified, but the current control fails to stabilize
Solution Approach 1:
The system initiates continuous illumination before the expected BD signal detection timing, creating a time margin that allows the energization current to stabilize before detection occurs. This preliminary action ensures both simplified detection timing and stable current control.
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 ensures stable control of the energization current for the semiconductor laser, preventing failures in laser beam detection and maintaining consistent image formation even with varying scan speeds.
Implementation Method 1
a semiconductor laser that emits a laser beam according with a current to be applied
Implementation Method 2
a light power detection unit that detects a light power of laser beam from the semiconductor laser
Data Source
AI summary
An image forming apparatus is provided. The image forming apparatus includes a semiconductor laser that emits a laser beam, a light power of the laser beam being controllable by a current applied to the semiconductor laser; a scanner unit that exposes a photosensitive element by scanning the photosensitive element using the laser beam; a light power detection unit that detects a light power of the laser beam; a current control unit that controls the current applied to the laser based on the light power of the laser beam; a home position detection unit that detects whether the laser beam is positioned at a scan home position; and a continuous illumination unit that commences continuous illumination of the laser at a time which is prior to a forecast time at which the home position detection unit is forecast to detect the laser beam.