Optical Scanning Device Bias Current Adjuster for Temperature Compensation
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Solution Overview
Problem
Existing optical scanning devices face challenges in maintaining consistent responsiveness of laser diodes across temperature changes without significant cost increases, due to complex and expensive circuit configurations required for automatic bias control.
Innovation Solution
An optical scanning device with a bias current adjuster using a thermistor and a fixed resistor, where the thermistor's resistance value changes with temperature, allowing for automatic adjustment of the bias current to maintain consistent responsiveness without increasing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an automatic bias control circuit is used to maintain consistent laser diode responsiveness across temperature changes, then the responsiveness stability is improved, but the circuit complexity and device cost increase
Solution Approach 1:
The patent employs a thermistor that automatically changes its resistance value in response to temperature variations, thereby self-adjusting the bias current without requiring external control circuits. This self-service mechanism maintains consistent laser diode responsiveness across temperature changes while avoiding the complexity of automatic bias control circuits
Solution Approach 2:
The patent utilizes the temperature-dependent resistance parameter of a thermistor to dynamically adjust the bias current. By changing the resistance parameter based on temperature, the system maintains optimal laser diode responsiveness without complex control mechanisms
2Measurement precision
If multiple switching elements and fixed resistors are used to control bias current in a step-by-step manner, then the bias current control precision is improved, but the device size and cost increase
Solution Approach 1:
The thermistor automatically adjusts the bias current based on temperature without requiring multiple switching elements or fixed resistors. This self-adjusting mechanism achieves precise bias current control while minimizing circuit size and component count
Solution Approach 2:
The patent uses the continuous resistance parameter change of the thermistor with temperature to achieve smooth bias current adjustment, eliminating the need for discrete step-by-step control with multiple components
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 maintains consistent responsiveness of the light source across temperature changes without increasing the device's cost, improving the optical scanning device's performance and reducing complexity.
Implementation Method 1
a bias current adjuster using a thermistor and a fixed resistor, where the thermistor's resistance value changes with temperature
Data Source
AI summary
An optical scanning device includes: a light source; a light source driver that provides the light source with a drive current, on which a bias current that fluctuates according to temperature change is superimposed, for emitting light from the light source; and a bias current adjuster that provides the light source driver with a bias control signal for adjusting a magnitude of the bias current, wherein the bias current adjuster includes a current value adjusting member that is capable of changing the magnitude of the bias control signal according to temperature change, and wherein the bias control signal that has automatically changed according to temperature change of the current value adjusting member is provided to the light source driver, so that the light source driver makes the magnitude of the bias current to be superimposed fluctuate, based on the provided bias control signal.