Fault Detector Circuit for Laser Emitter Safety
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Solution Overview
Problem
Existing fault detector circuits for laser emitters in electronic devices fail to effectively detect short circuits and leakage, potentially exposing users to unsafe levels of laser radiation.
Innovation Solution
A fault detector circuit utilizing a first NMOS transistor and a comparator to monitor the voltage of the laser emitter, generating a detecting signal to cut off the supply voltage when a short circuit or leakage is detected, thereby preventing user exposure to high energy radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a fault detector circuit is implemented to detect short circuits and leakage in the laser emitter, then eye safety is improved, but the device complexity increases due to additional circuit components
Solution Approach 1:
The fault detector circuit performs preliminary detection of short circuits and leakage conditions in the laser emitter before the laser is activated. The comparator continuously monitors the voltage at the drain of the first NMOS transistor and compares it with a reference voltage to determine if a fault condition exists, generating a detecting signal that prevents laser activation or triggers shutdown if a fault is detected.
Solution Approach 2:
The patent introduces an intermediary fault detector circuit that acts as a mediator between the laser emitter control system and the safety requirements. The circuit uses a comparator as an intermediary component to indirectly detect fault conditions by monitoring voltage levels, rather than directly measuring laser output or physical conditions, thereby simplifying the overall system while maintaining safety.
2Measurement precision
If the comparator continuously monitors the drain voltage to detect faults, then detection precision is improved, but energy consumption increases
Solution Approach 1:
The fault detection operates periodically rather than continuously. The comparator monitors the voltage condition and generates a detecting signal when fault conditions are present. The first NMOS transistor is turned off before the laser emitter is driven, and the detection occurs at specific intervals (before activation and during operation), reducing continuous energy consumption while maintaining detection precision through strategic monitoring points.
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 circuit effectively detects short circuits and leakage in the laser emitter, ensuring timely cutoff of the supply voltage to prevent user exposure to unsafe laser radiation, enhancing eye safety in electronic devices.
Implementation Method 1
the comparator compares a voltage of the drain of the first NMOS transistor with the reference voltage to generate a first detecting signal
Implementation Method 2
the first NMOS transistor is turned on by the control voltage
Data Source
AI summary
A fault detector circuit is provided for detecting or controlling any signal related to a laser emitter in an electronic device. The fault detector circuit includes a first NMOS transistor and a comparator. A drain of the first NMOS transistor is coupled to a first supply voltage through the laser emitter. A gate of the first NMOS transistor is coupled to a control voltage. A source of the first NMOS transistor is grounded. The comparator is coupled to the drain of the first NMOS transistor and a reference voltage. The comparator compares a voltage of the drain of the first NMOS transistor with the reference voltage to generate a first detecting signal for determining whether or not the first supply voltage of the laser emitter needs to be cut off.