Laser Circuit Substrate Impedance Equalization for Noise Reduction
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
High-speed and high-quality image printing in laser beam printers is hindered by noise currents generated due to impedance differences in semiconductor laser elements and wiring, which also lead to radiant noise, and existing solutions fail to simultaneously achieve high-speed driving and noise reduction.
Innovation Solution
A laser circuit substrate design with capacitors strategically placed to equalize the impedances of the light-emitting circuit and compensation circuit, allowing for effective noise cancellation and improved wiring flexibility, enabling high-speed and high-quality image printing while reducing radiant noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a filter is arranged on wiring which connects a semiconductor laser element to a driving semiconductor device to suppress noise currents, then noise reduction is improved, but the deterioration of the light-emitting current waveform worsens as driving frequency increases
Solution Approach 1:
A compensation circuit is introduced as an intermediary element between the light-emitting circuit and the main wiring. This compensation circuit includes a compensation semiconductor device and compensation wiring that generates a compensation current to counteract the noise currents flowing in the main power transmission wiring and main ground wiring, thereby suppressing noise without degrading the light-emitting current waveform
Solution Approach 2:
The compensation circuit creates a copied version of the noise current path with opposite polarity. By generating a compensation current that mirrors the noise current characteristics but with opposite phase, the noise currents are canceled out at the main wiring, effectively reducing electromagnetic radiation without affecting the original light-emitting circuit
2Productivity
If the driving frequency of semiconductor laser elements is increased to achieve high-speed image printing, then productivity is improved, but noise currents generated due to impedance differences increase
Solution Approach 1:
The compensation circuit operates as a feedback mechanism that continuously counteracts noise currents generated at high driving frequencies. The compensation semiconductor device and compensation wiring are configured to generate compensation currents that automatically adjust to cancel the noise currents flowing in the main wiring, enabling high-speed operation while maintaining low noise levels
Solution Approach 2:
The invention changes the electrical parameters of the circuit by introducing the compensation circuit with specific impedance characteristics. The compensation wiring and compensation semiconductor device are designed with parameters that create a balanced impedance relationship, allowing the system to operate at high frequencies without generating excessive noise currents
3Device complexity
If main wiring is connected to a power supply cable to simplify circuit design, then device complexity is reduced, but radiant noise is inconveniently produced when the power supply cable acts as an antenna
Solution Approach 1:
The compensation circuit acts as an intermediary between the main wiring and the power supply cable. By generating compensation currents that cancel noise currents in the main wiring, it prevents the power supply cable from acting as an antenna and radiating noise, thus maintaining simple circuit design while reducing radiant noise
4Manufacturing precision
If the number of semiconductor laser elements is increased to improve image printing quality, then image quality is improved, but noise currents increase due to more components and wiring
Solution Approach 1:
The invention segments the circuit into a light-emitting circuit portion and a compensation circuit portion. Each semiconductor laser element circuit can be independently compensated by its corresponding compensation circuit, allowing multiple laser elements to operate simultaneously with individual noise cancellation, thus improving image quality while controlling noise currents
Data Source
AI summary
This invention makes it possible to meet a requirement of high-quality image printing and high-speed driving of a semiconductor laser driver in a laser beam printer or the like while suppressing radiant noise. A laser circuit substrate includes a first wiring pattern and second wiring pattern connected to a main wiring pattern, a first circuit which is connected to the first wiring pattern and has a semiconductor laser element and a driving circuit for driving the semiconductor laser element, a second circuit which is connected to the second wiring pattern and compensates noise generated by the first circuit, a first capacitor which is connected to a first point in the first wiring pattern, and a second capacitor which is connected to a second point in the second wiring pattern. The positions of the first point and second point are set such that the sum of the impedances of the first wiring pattern and first circuit viewed from the first point, and the sum of the impedances of the second wiring pattern and second circuit viewed from the second point are substantially equal to each other.