Optical Fiber Temperature Sensor Spacer for Stable IR Measurement
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Solution Overview
Problem
Infrared light reflection and interference at the interface between the protective window and air layer in temperature sensors used in molding machines cause unstable measurement results due to changes in the air layer thickness from thermal expansion, affecting the accuracy of temperature measurements.
Innovation Solution
A temperature sensor design that includes a spacer between the fiber probe and protective window, maintaining a stable distance through a transmission hole in the spacer to suppress optical interference, ensuring a thick air layer of at least 1 mm to stabilize measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protective window is used to protect the optical fiber, then the optical fiber is protected from contamination, but optical interference occurs due to infrared light reflection at the interface between the protective window and air layer
Solution Approach 1:
The patent introduces a spacer as an intermediary component between the protective window and the optical fiber. The spacer eliminates the air layer that causes optical interference while maintaining the protective function. The spacer's material and structure are designed to prevent infrared light reflection at interfaces, thereby resolving the contradiction between protection and measurement precision.
2Device complexity
If the protective window and optical fiber are in direct contact, then the structure is simple, but optical interference occurs due to the air layer formed between them under high-temperature conditions
Solution Approach 1:
The spacer serves as a mediator that replaces the problematic air layer while maintaining structural simplicity. The spacer is designed with specific material properties that prevent optical interference, and its geometry allows for easy integration into the existing sensor structure without complicating the overall design.
Solution Approach 2:
The patent changes the physical parameters of the interface between the protective window and optical fiber by introducing the spacer. This modifies the optical path and eliminates the conditions for optical interference, while the spacer's thermal expansion characteristics are designed to maintain stable performance under high-temperature conditions.
3Volume of moving object
If the air layer thickness is small, then the structure is compact, but the degree of optical interference changes due to thermal expansion of the protective window
Solution Approach 1:
The spacer acts as a stable intermediary that maintains a consistent distance between the protective window and optical fiber, eliminating the variable air layer whose thickness changes with thermal expansion. The spacer's material properties are selected to provide thermal stability, ensuring that the optical path remains constant under varying temperature conditions.
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 spacer maintains a stable distance between the optical fiber and protective window, reducing optical interference and fluctuations in measurement results, while also dispersing pressure from the molten resin, thereby enhancing measurement stability and protecting the optical fiber.
Implementation Method 1
a fiber probe into which an optical fiber for measuring the temperature of a molten resin filled in a cavity is threaded communicates with the cavity to transmit infrared light emitted from the molten resin to a detector through the optical fiber
Implementation Method 2
the protective window is formed of a transparent material, allowing infrared light to pass through the protective window and enter the optical fiber from the incident surface
Implementation Method 3
when an air layer exists between the protective window and the incident surface, the light may be reflected at an interface between the protective window and the air layer or an interface between the air layer and the incident surface depending on the conditions of the air layer or the like, which may cause optical interference
Implementation Method 4
since the protective window, the distal end portion of the optical fiber, and the like are exposed to a high-temperature environment, for example, when the thickness of the air layer changes due to the thermal expansion of the protective window or the like
Data Source
AI summary
A temperature sensor used in a molding machine includes: a tubular fiber probe into which an optical fiber is threaded; an outer casing having a shaft into which the fiber probe is inserted; a protective window that is located on a distal end side of the fiber probe and is formed of glass; and a spacer that is disposed between the fiber probe and the protective window and has a space section both sides of which are in contact with the fiber probe and the protective window. The space section has a transmission hole formed to serve as a path leading infrared light to the optical fiber, and a diameter of the transmission hole is equal to or greater than an outer diameter of the optical fiber.