Laser Diode Array Cross-Talk Compensation via ECT Coefficients
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Solution Overview
Problem
The electric cross-talk (ECT) effect in laser diode arrays causes interference between laser channels due to parasitic capacitance and inductance, leading to voltage/current spikes and reduced print quality by affecting the desired current profile for laser power output.
Innovation Solution
A method involving an image sensor captures images of laser spots before and during the switching of other laser diodes to calculate an ECT coupling coefficient, allowing for the generation of a driving signal that compensates for the ECT effect by superposing the desired current profile with an ECT prediction signal, ensuring accurate laser power output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If laser diodes are switched on and off to generate laser pulses for printing, then printing functionality is achieved, but electric cross-talk effects cause voltage/current spikes and interfere with other laser channels
Solution Approach 1:
The patent applies preliminary action by measuring the ECT coupling coefficients before actual printing operations. The system characterizes the cross-talk effects in advance by switching individual laser diodes and measuring the resulting voltage/current effects on other channels. These pre-measured coefficients are stored and used during printing to calculate and compensate for ECT effects in real-time, allowing the system to maintain signal stability while achieving high-speed printing functionality
2Productivity
If multiple laser diodes operate simultaneously in an array, then printing coverage and speed are improved, but parasitic capacitance and inductance cause interference between channels
Solution Approach 1:
The patent implements feedback by using the pre-measured ECT coupling coefficients to calculate compensation signals during printing operations. The system continuously monitors the desired current profile for each laser diode, calculates the expected cross-talk interference using the stored coefficients, and adjusts the driving signals accordingly. This feedback mechanism allows multiple laser diodes to operate simultaneously without mutual interference, maintaining both printing coverage and signal integrity
3Manufacturing precision
If driving signals are applied to achieve desired current profiles for laser power output, then laser printing functionality is achieved, but ECT effects cause voltage/current spikes that deviate from desired profiles
Solution Approach 1:
The patent applies preliminary anti-action by calculating compensation signals that counteract the expected ECT effects before they can disrupt the desired current profiles. Using the pre-measured coupling coefficients, the system determines the magnitude and timing of cross-talk interference and applies opposing voltage/current adjustments to cancel out the harmful effects. This allows the system to maintain accurate laser power control and stable current profiles even when multiple laser diodes are activated
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 effectively reduces print quality issues such as scan banding and image graininess by accurately controlling laser diode current profiles, even under the influence of ECT effects, thereby enhancing overall print quality.
Implementation Method 1
capturing, by an image sensor, a first image of a first laser spot of a first laser diode
Data Source
AI summary
An electric cross-talk, ECT, effect of laser-diode array is measured by capturing a first image of a first laser spot of a first laser diode with a second laser diode being turned off (10) and a second image of a second laser spot of the first laser diode while switching on the second laser diode (20). A spot-energy ratio is determined (30) by processing the images, and an ECT-coupling coefficient on the first laser diode is calculated (40) by switching the second laser diode. Compensating for the ECT effect includes determining a signal for predicting the ECT effect on the first laser diode by switching the second laser diode, and generating a driving signal based on a desired current profile and the ECT-prediction signal.