Optical Scanning Apparatus Velocity Control for Laser Diode Lifespan
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Solution Overview
Problem
Optical scanning apparatuses face challenges in maintaining optimal revolution numbers for rotary deflectors across varying process linear velocities, leading to reduced printing speed, productivity, and image quality issues when handling different paper types and color printing, due to limitations in motor performance and exposure light control.
Innovation Solution
The optical scanning apparatus is designed with a multi-beam configuration and a method to control the rotary deflector's revolution number within a narrow range, adjusting the number of light sources and reflective surfaces to maintain optimal pixel density and exposure energy, while ensuring the synchronous detector receives a constant light amount to regulate the writing start position accurately.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the process linear velocity is reduced to handle thick paper or perform color printing, then the heat amount per unit time increases to secure fixability, but the printing speed and productivity are reduced
Solution Approach 1:
The patent applies dynamics by making the process linear velocity changeable according to different printing modes. The system dynamically adjusts the process linear velocity based on the type of printing task (monochrome vs. color, standard paper vs. thick paper) to optimize both fixing temperature and printing speed. This resolves the contradiction by allowing the system to operate at high speeds for monochrome printing while reducing speed only when necessary for color printing or thick paper handling.
2Adaptability or versatility
If the range of process linear velocity is increased to accommodate various paper types and modes, then the range of revolution number of the rotary deflector must be increased, but the motor characteristics become unsatisfactory and image distortion occurs
Solution Approach 1:
The system dynamically adjusts the process linear velocity within a limited range that maintains optimal motor characteristics. Rather than allowing the rotary deflector to operate across a wide range of revolution numbers, the system keeps the velocity changes controlled and predictable, ensuring the motor operates in its optimal performance zone while still providing adaptability for different printing modes.
Solution Approach 2:
The patent employs feedback mechanisms through synchronous detectors that receive light beams to detect the start position of main scan. This feedback system allows real-time monitoring and adjustment of the scanning process, ensuring that even when process linear velocity changes, the image quality and motor characteristics remain within acceptable ranges. The feedback enables precise control that prevents image distortion.
3Use of energy by moving object
If the process linear velocity is changed to maintain constant exposure energy per unit time, then the amount of exposure light must be changed, but the synchronous detector output varies causing writing start position regulation issues
Solution Approach 1:
The patent uses synchronous detectors as feedback devices that receive light beams and detect the start position of the main scan. By using the synchronous detector output as a reference signal, the system can accurately determine the writing start position even when exposure light amount changes. The feedback mechanism compensates for variations in detector output caused by changes in process linear velocity, maintaining precise position regulation.
Solution Approach 2:
The system changes the parameter of exposure light amount in response to process linear velocity changes to maintain constant exposure energy per unit time. This parameter adjustment is coordinated with the synchronous detector system, which is designed to provide stable reference signals across different operating conditions. The combined approach of parameter change and feedback control resolves the contradiction between energy maintenance and position precision.
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 enhances printing speed and productivity by maintaining image quality across different paper types and color modes, reducing the risk of image distortion and extending the lifespan of laser diodes, thereby improving the reliability and efficiency of the image forming apparatus.
Implementation Method 1
a light flux or an light beam from an optical source is deflected by a rotary deflector so that the photoreceptor is exposed and scanned by the light flux or the light beam
Implementation Method 2
A laser diode used as an optical source
Implementation Method 3
the synchronous detector equipped with a photo IC for receiving light on a printed circuit board
Data Source
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AI summary
An optical scanning apparatus includes a plurality of light sources (51,52) for emitting light beams and a rotary deflector (57) for deflecting the light beams. A revolution number (Rm) of the rotary deflector is reduced to Rdef × (V/Vmax) if V/Vmax is greater than a predetermined value; and the revolution number (Rm) thereof is reduced to Rdef × (V/Vmax) × m and the number of the light beams is reduced to Ndef/m if V/Vmax is not greater than the predetermined value. V is a process linear velocity of the image forming apparatus; Vmax is a maximum process linear velocity thereof; Ndef is the number of the light beams at the maximum process linear velocity Vmax; and Rdef is the revolution number of the rotary deflector thereat; and m is a positive integer, and Vmax is greater than V (Vmax>V).