VCSEL Light Source Device Stabilizing Output via Aperture Intensity Control
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Solution Overview
Problem
Conventional light source devices, particularly those using VCSELs, face challenges in maintaining stable optical output over time due to fluctuations in light intensity, leading to image quality issues such as density unevenness and color unevenness, which are exacerbated by the narrow optical output range, increasing costs and reducing image quality.
Innovation Solution
A light source device incorporating a surface emitting laser with a coupling optical system and an aperture member that regulates the light beam, ensuring a specific relationship between light intensities at different times to stabilize the output, thereby reducing fluctuations and maintaining image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a VCSEL is used as the light source, then costs are reduced and electrical power consumption is lowered, but light intensity fluctuations occur causing image quality degradation
Solution Approach 1:
The patent applies preliminary action by controlling the driving current waveform in advance to compensate for expected light intensity fluctuations. Specifically, the current waveform is designed with predetermined variations (e.g., increasing or decreasing current levels) to counteract the natural tendency of VCSELs to fluctuate in light output, thereby stabilizing the light intensity before it reaches the optical system and preventing image quality degradation.
Solution Approach 2:
The patent implements feedback control by monitoring the light intensity output from the VCSEL and adjusting the driving current accordingly. A sensor detects the actual light intensity, and this information is fed back to the control circuit, which then modifies the driving current waveform to maintain stable light output, effectively compensating for fluctuations caused by temperature changes and VCSEL characteristics.
2Productivity
If the driving current is increased to improve output speed, then image output speed increases, but light intensity fluctuations are exacerbated
Solution Approach 1:
The patent applies dynamics by making the driving current waveform adjustable and adaptable rather than fixed. The control circuit dynamically modifies the current waveform parameters (amplitude, pulse width, frequency) based on real-time light intensity feedback, allowing the system to maintain stable light output even at high driving currents required for fast image output speeds.
Solution Approach 2:
The patent utilizes parameter changes by varying the driving current characteristics (such as pulse width modulation depth, frequency, or amplitude) to optimize both output speed and light stability. By changing these electrical parameters dynamically, the system achieves high productivity while compensating for the increased light fluctuations that accompany higher driving currents.
3Adaptability or versatility
If temperature changes occur during operation, then operational flexibility is maintained, but light intensity and wavelength fluctuate causing image quality degradation
Solution Approach 1:
The patent implements feedback control that specifically addresses temperature-induced fluctuations. Temperature sensors or light intensity sensors monitor changes caused by thermal effects, and the control circuit adjusts the driving current in real-time to compensate for these changes, maintaining stable optical output across varying environmental temperatures.
Solution Approach 2:
The patent applies parameter changes by adjusting the driving current characteristics in response to temperature variations. As temperature changes affect VCSEL performance (wavelength shift, intensity variation), the control system modifies current parameters such as bias level or modulation depth to counteract these thermal effects and maintain consistent optical output.
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 stabilizes the light output, reducing fluctuations and maintaining image quality even with changes in temperature or photosensitivity, improving product yield and adaptability to various environments, while allowing for high image density and increased scanning speed.
Implementation Method 1
a light source device (10) including a surface emitting laser (111)
Implementation Method 2
a coupling optical system (13) that couples a light beam output from the surface emitting laser (111)
Data Source
AI summary
In a light source device including an aperture member that regulates a light beam, |(Pap1−Pap2)/Pap2|<|(P1−P2)/P2| is satisfied where P2 is a light intensity of the light beam entering the aperture member at a time t2 when 2 microseconds have passed since current was applied to the laser, P1 is a light intensity of the light beam entering the aperture member at a time t1 when 40 nanoseconds have passed since a light intensity of the light beam entering the aperture member reached 0.1 time the light intensity P2, Pap2 is a light intensity of the light beam output from the aperture member at the time t2, and Pap1 is a light intensity of the light beam output from the aperture member at a time t1′ when 40 nanoseconds have passed since a light intensity of the light beam output from the aperture member reached 0.1 time the light intensity Pap2.