Multi-beam Laser Power Control Circuit APC Signal Priority
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Solution Overview
Problem
The existing multi-beam laser power control circuits face challenges in performing accurate Automatic Power Control (APC) for semiconductor laser arrays due to limitations in time margin setting and noise reduction, especially when the number of semiconductor lasers increases, leading to potential power control errors and reduced efficiency in high-speed image forming applications.
Innovation Solution
The implementation of an APC signal selection circuit that determines the priority order of APC execution signals and eliminates the need for complex timing control, allowing for sequential APC operations without time margins, thereby reducing the time required for power control and enhancing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If time margins are inserted between APC execution signals for multiple semiconductor lasers, then the APC operations can be sequentially executed without overlap, but the total time required for power control increases and productivity decreases
Solution Approach 1:
The invention changes the timing parameter of APC execution by eliminating time margins between sequential APC operations. The control circuit executes APC for multiple semiconductor lasers in rapid succession without inserting delay periods, thereby reducing the total power control time while maintaining execution accuracy through the control circuit's ability to handle back-to-back APC cycles.
2Productivity
If APC execution signals are transmitted without time margins, then the power control time is reduced and productivity improves, but the influence of external noises and substrate wiring parasitics increases causing reliability to deteriorate
Solution Approach 1:
The invention introduces a control circuit as an intermediary between the external noise environment and the APC execution signals. This control circuit actively compensates for the effects of external noises and substrate wiring parasitics by dynamically adjusting the APC execution timing and signal levels, enabling rapid back-to-back APC operations without time margins while maintaining execution accuracy.
3Ease of manufacture
If the number of photodiodes is reduced to integrate with semiconductor laser arrays, then device complexity is reduced and ease of manufacture improves, but the ability to perform accurate APC for each laser decreases
Solution Approach 1:
The invention makes a single photodiode perform multiple functions by sequentially detecting the output power of multiple different semiconductor lasers. The control circuit manages the sequential operation, allowing one photodiode to serve multiple measurement purposes through time-multiplexed detection, thereby achieving accurate APC for each laser without requiring separate photodiodes for each device.
4Reliability
If LPF circuits are inserted to reduce external noise influence, then reliability improves, but additional delay components are added increasing the time required for APC operations
Solution Approach 1:
The invention uses feedback control within the control circuit to compensate for noise effects without requiring LPF circuits. The control circuit monitors the APC execution signals and photodiode output in real-time, dynamically adjusting control parameters to reject external noise interference, thereby achieving noise resistance without adding the time delay that would result from LPF circuit insertion.
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 enables more accurate and efficient APC, reducing the time period needed for power control and facilitating the development of high-speed image forming apparatuses by minimizing the impact of substrate configuration and noise reduction circuits.
Implementation Method 1
the semiconductor laser is operated so that the output power of the semiconductor laser is received by using a photodiode (FD)
Data Source
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AI summary
A disclosed multi-beam laser power control circuit includes a light receiving element receiving power output from semiconductor lasers to control output power of a semiconductor laser array having plural semiconductor lasers, automatic power control circuits (APC circuits) controlling emission power output from semiconductor lasers based on received corresponding automatic power control execution signals so as to be set to predetermined emission power based on output from the light receiving element, and APC execution signal input terminals inputting the corresponding automatic power control execution signals, wherein, when plural APC execution signals input to the corresponding APC execution signal input terminals are overlapped, the automatic power control circuits (APC circuits) to be preferentially operated is determined based on input timings of the APC execution signals and operated.