Laser Interlock Circuit Using Semiconductor Switching
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Solution Overview
Problem
Laser processing apparatuses with high throughput require frequent operation of mechanical relays for interlock functions, leading to short lifespan and reliability issues due to frequent opening and closing of protection housings during object handling, especially when using transmission optical fibers.
Innovation Solution
A laser processing apparatus incorporating semiconductor switches on the drive voltage path and mechanical relays on the AC voltage path, with a control unit monitoring output voltages to shut off power supply when abnormalities occur, reducing the operational frequency of mechanical relays and extending lifespan.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a mechanical relay is used in the interlock circuit to shut off power supply when protection housing is opened, then the interlock function can be implemented, but the mechanical relay requires frequent replacements due to short lifespan from frequent operations
Solution Approach 1:
The patent replaces the mechanical relay with a semiconductor switch in the interlock circuit. The semiconductor switch is driven by a delay drive circuit that receives signals from the interlock signal generator when the protection housing is opened. This substitution eliminates the mechanical moving parts that limit relay lifespan, thereby resolving the contradiction between maintaining reliable interlock function and extending component lifespan through frequent operations.
2Reliability
If a mechanical shutter is provided inside the laser light source to shut off laser light, then the interlock function can be implemented, but it is difficult to provide the mechanical shutter inside the laser light source when using transmission optical fiber
Solution Approach 1:
The patent replaces the mechanical shutter with an electrical control system consisting of an interlock signal generator and semiconductor switches. When the protection housing is opened, the interlock signal generator detects this and sends a signal to the delay drive circuit, which then actuates the semiconductor switch to shut off the laser light source electrically. This eliminates the need for mechanical shutters inside the laser light source, resolving the contradiction between achieving interlock function and maintaining ease of manufacture with fiber transmission systems.
3Productivity
If the interlock circuit is frequently operated due to frequent opening and closing of protection housing in high throughput laser processing, then the interlock function remains effective, but the mechanical relay lifespan decreases requiring frequent replacements
Solution Approach 1:
The patent substitutes the mechanical relay with a semiconductor switch that has no mechanical moving parts. The semiconductor switch is controlled by an interlock signal generator and delay drive circuit that respond to protection housing opening events. This allows the system to maintain high productivity with frequent protection housing operations without suffering from mechanical relay lifespan degradation, as the semiconductor switch can handle frequent operations without wear.
4Duration of action of stationary object
If a semiconductor switch is used instead of mechanical relay to extend lifespan, then the component lifespan increases, but additional control circuits (delay drive circuit, interlock signal generator) are required increasing system complexity
Solution Approach 1:
The patent replaces the mechanical relay with a semiconductor switch controlled by a delay drive circuit and interlock signal generator. While this adds electronic control circuits, it eliminates the mechanical relay and its associated mechanical complexity. The electronic control system provides longer component lifespan and requires less maintenance, trading mechanical simplicity for electronic control complexity while achieving overall system improvement.
Solution Approach 2:
The delay drive circuit is designed to provide a delayed response when the interlock signal generator detects that the protection housing has been opened. This preliminary timing control ensures that the semiconductor switch is actuated at the appropriate moment, allowing for coordinated shutdown of the laser light source and other components. This preliminary action mechanism simplifies the overall control logic by providing automatic timing rather than requiring complex synchronous control of multiple components.
Data Source
AI summary
A laser processing apparatus includes: a laser light source that oscillates a laser light; a transmission optical fiber that transmits the oscillated laser light from the laser light source; a laser irradiation unit that irradiates an object with the laser light transmitted by the transmission optical fiber; a power supply that receives an input of an AC voltage to generate a drive voltage for enabling the laser light source to oscillate the laser, and to apply the drive voltage to the laser light source; a semiconductor switch provided on a path of the drive voltage between the power supply and the laser light source; a mechanical relay provided on a path of the AC voltage to the power supply.