Laser Light Source Module Bypass Circuit Failure Detection
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Solution Overview
Problem
Existing laser light source modules connected in series face critical failures when a laser diode does not emit light, leading to reduced light output, increased thermal load, and reliability issues, as existing solutions either require excessive cooling or fail to detect non-emitting diodes maintaining diode characteristics.
Innovation Solution
A laser light source module with a bypass circuit and light detection circuit that diverts current to a bypass circuit when the laser diode does not emit light, using an N channel MOSFET switching element and a photovoltaic output photo coupler to maintain power supply stability and detect laser light, allowing continued operation and specifying defective diodes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a substitute diode is parallelly connected to the laser diode to maintain operation during failure, then the light source device can continue operating, but the substitute diode generates excessive heat that requires additional cooling capacity and space
Solution Approach 1:
A switching element is introduced as an intermediary between the laser diode and substitute diode. The switching element controls current flow, allowing the system to switch between normal operation (current through laser diode) and failure mode (current through substitute diode). This mediator enables reliable continuous operation while managing heat generation by activating the substitute path only when needed.
Solution Approach 2:
The system changes the electrical parameter (current flow path) based on the operational state. When the laser diode fails, the control circuit detects the failure and changes the circuit configuration by activating the switching element, thereby changing which component carries the current. This parameter change allows the substitute diode to handle the load only when necessary, managing heat generation effectively.
2Measurement precision
If the forward voltage of the substitute diode is set higher than the laser diode to enable failure detection, then the failure can be detected, but excessive heat is generated in the substitute diode during normal operation
Solution Approach 1:
The circuit configuration is made dynamic through the switching element that can change the circuit state based on detected conditions. During normal operation, the switching element keeps the substitute diode inactive (high impedance state). Upon detecting laser diode failure through voltage threshold comparison, the switching element activates to redirect current through the substitute diode. This dynamic behavior enables failure detection without continuous heat generation in the substitute diode.
Solution Approach 2:
The failure detection function is extracted as a separate control mechanism independent of the main current path. The control circuit monitors voltage across the laser diode and uses this information to control the switching element. This separation allows the substitute diode to be prepared for failure detection without being continuously activated, thereby avoiding unnecessary heat loss during normal operation.
3Reliability
If a switching element is parallelly connected to the laser diode with voltage threshold detection, then current can be diverted upon failure, but the system complexity increases
Solution Approach 1:
The switching element serves multiple functions: it acts as a normal circuit component during operation and automatically activates as a protective device when failure is detected. The control circuit performs both monitoring of the laser diode voltage and control of the switching element. This multi-functionality reduces the need for separate dedicated components for each function, thereby managing system complexity while achieving failure tolerance.
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
Enables continued light output from other modules when a diode fails, reduces thermal load, and effectively detects and specifies defective diodes, enhancing the reliability and efficiency of the light source device.
Implementation Method 1
a photovoltaic output photo coupler to maintain power supply stability and detect laser light
Implementation Method 2
a bypass circuit and light detection circuit that diverts current to a bypass circuit when the laser diode does not emit light, using an N channel MOSFET switching element
Data Source
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AI summary
It is an object of the present invention to provide a laser light source module capable of diverting current flowing to a laser diode when the laser diode does not emit light. A laser light source module 100 includes a laser diode 3, a bypass circuit 4 parallelly connected to the laser diode 3 and diverting current flowing to a laser diode in an on state, a light detection circuit 5 detecting laser light of the laser diode 3, and the bypass circuit switching circuit 6 switching the bypass circuit 4 to the on state in accordance with a control signal being input thereto, and the bypass circuit switching circuit 6 can switch the bypass circuit 4 to the on state in accordance with a state where the light detection circuit 5 does not detect the laser light.