Laser Diode Driving Circuit for Synchronized RGB Projection Startup
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Solution Overview
Problem
Advanced projection devices using R, G, and B laser diode light source modules experience asynchronous startup sequences due to differing compensation capacitors, leading to poor-quality startup images with color mixing issues.
Innovation Solution
A light source driving circuit incorporating delay and hysteresis comparator circuits to synchronize the startup timing of laser diode driving circuits, ensuring synchronized drive currents to all modules, eliminating color mixing during image projection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If different compensation capacitors are used for R, G, and B laser diode light source driving circuits to compensate for characteristic differences, then the compensation accuracy is improved, but the startup timing becomes asynchronous
Solution Approach 1:
The delay circuit introduces a preliminary time delay to the selection signal before it reaches the driving unit. This preliminary action compensates for the timing differences caused by different compensation capacitors, ensuring that all laser diode light source modules start up simultaneously despite having different compensation requirements.
Solution Approach 2:
The delay circuit acts as an intermediary between the control signal source and the driving unit. It mediates the timing relationship by introducing a controlled delay, allowing the system to maintain both accurate compensation (through different capacitors) and synchronized startup (through the delay circuit's timing adjustment).
2Reliability
If asynchronous startup sequences occur in laser diode light source driving circuits, then individual module compensation is optimized, but the overall image quality during startup deteriorates
Solution Approach 1:
The delay circuit performs a preliminary timing adjustment to ensure all driving circuits start simultaneously. This preliminary synchronization prevents the color mixing issues that would otherwise occur during startup, while still allowing each module to have its optimized compensation capacitor for reliable operation.
Data Source
AI summary
The application discloses a projection device comprising: a plurality of optical source modules; and a plurality of optical source driving circuits. Each of the optical source driving circuits includes: an optical source driving unit, for receiving and being controlled by a selection signal and a pulse width modulation signal, the pulse width modulation signal controlling a current amplitude of the drive current from the optical source driving unit to the optical source module; and a delay circuit for controlling the selection signal based on the adjusted threshold voltage to determine when to release the selection signal, the plurality of delay circuits in the plurality of optical source driving circuits release the selection signals synchronously, enabling the plurality of optical source driving circuits to synchronously output the plurality of drive currents to the plurality of optical source modules.