Multi-beam Laser Driver Correcting Output Differences
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Solution Overview
Problem
Existing multi-beam light sources with multiple light emitting elements face challenges in correcting relative output differences between individual elements, leading to non-uniform irradiation intensity, which affects image quality in electrophotographic image forming processes.
Innovation Solution
A multi-beam light source driving device with a driver and correction parallel units that generate and adjust control signals using pulse density modulation and low-pass filtering to equalize light emitting power across multiple light emitting elements, addressing individual differences and ensuring uniform irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a multi-beam light source with multiple light emitting elements is used to speed up exposure processing, then productivity is improved, but device complexity increases due to the need to correct relative output differences between individual elements
Solution Approach 1:
The correction system is segmented into multiple independent correction units, with each unit corresponding to one light emitting element. Each correction unit independently processes the correction signal for its associated element, allowing parallel correction operations that match the parallel beam structure and avoid centralized complexity bottlenecks.
Solution Approach 2:
The correction units are designed with universal functionality, where each unit can process correction signals for its corresponding light emitting element using the same operational amplifiers and filtering circuits. This multi-functional design allows the system to handle multiple elements with identical correction mechanisms, reducing overall system complexity through standardization.
2Manufacturing precision
If correction values are converted using a DA converter to control light emitting power, then manufacturing precision is improved by correcting relative output differences, but object-generated harmful factors increase due to ripple in the analog signal
Solution Approach 1:
An operational amplifier is introduced as an intermediary component between the DA converter and the light emitting element. This operational amplifier acts as a buffer and signal conditioning stage that isolates the ripple from the DA converter while providing stable control voltage to the light emitting element, thus eliminating the harmful ripple effect.
Solution Approach 2:
The system changes the electrical parameters of the control signal by using operational amplifiers to adjust voltage levels and filtering circuits to modify frequency characteristics. By changing these parameters through active filtering, the ripple frequency components are attenuated while the useful control signal is preserved, achieving ripple reduction without sacrificing correction precision.
3Reliability
If a low-pass filter is applied to reduce ripple in the analog signal, then reliability is improved by reducing harmful ripple effects, but device complexity increases due to additional filtering components
Solution Approach 1:
The filtering function is merged with the existing operational amplifier-based correction units. The low-pass filtering is integrated into the same circuitry that performs the correction signal amplification, combining multiple functions (amplification, filtering, and signal conditioning) into a single unified correction unit for each light emitting element. This reduces overall device complexity by eliminating separate filtering stages.
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
The solution effectively corrects relative output differences, enhancing the uniformity of light irradiation and improving image quality by digitally adjusting the light emitting power of each element, thereby reducing ripple effects and maintaining image consistency.
Implementation Method 1
a first pulse signal which is a pulse density modulation signal according to the multiplication result by the first multiplier
Implementation Method 2
the first filter applies low-pass filter processing to the first pulse signal to thereby generate the first control signal including the first correction component
Implementation Method 3
a light source including a light emitting element that emits a light beam, for example, a laser diode that emits a laser beam as a light beam
Data Source
AI summary
A light source according to the present invention is for an exposure device of a multifunction peripheral and includes a multi-beam light source. Two laser diodes included in the multi-beam light source are individually driven by a laser driver. Reference signals Vref1 and Vref2 used to control the light emitting power of the laser diodes are individually generated by two reference signal generation circuits. The reference signals Vref1 and Vref2 are each generated by processing including digital calculation, and at least one of the reference signals Vref1 and Vref2 includes a component for correcting the relative output difference of the laser diodes.