Infrared Temperature Sensor Emissivity Correction via Light Guide Geometry
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Solution Overview
Problem
Existing infrared temperature sensors for toner fixing units in image forming apparatuses face structural errors due to component dimension and assembly accuracy issues, leading to shifts in detected temperature, which are corrected using mechanical elements or coating films, but these solutions either reduce visual field area or impair responsiveness.
Innovation Solution
An infrared temperature sensor with a heat conversion film and a blocking part to adjust emissivity on the irradiation surface, allowing for the formation of a correction region with varying emissivity to correct detected temperature without altering the heat conversion film, maintaining high responsiveness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a coating film is provided on the heat conversion film to adjust infrared absorptance, then temperature detection accuracy is improved, but heat capacity increases and responsiveness deteriorates
Solution Approach 1:
The patent replaces the coating film approach with a light guide part having a specific internal structure. The light guide part uses total internal reflection and geometric design to control infrared ray distribution, substituting the need for emissivity-adjusting coatings while maintaining thin profile and fast response characteristics of the heat conversion film.
Solution Approach 2:
The patent shifts the correction mechanism from the surface dimension (coating film on heat conversion film) to the spatial/structural dimension (internal geometry of light guide part). By designing the light guide part's internal structure with specific angles and configurations, it controls infrared ray paths and distribution without adding material layers, thus maintaining responsiveness while improving accuracy.
2Measurement precision
If a mechanical element is added to adjust or correct temperature shift, then temperature detection accuracy is improved, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent merges the temperature correction function into the light guide part itself. The light guide part simultaneously performs its primary function of guiding infrared rays to the detection element and its secondary function of correcting temperature measurement accuracy through its internal geometric structure, eliminating the need for separate mechanical adjustment elements.
Solution Approach 2:
The light guide part is designed to serve multiple functions: (1) guiding infrared rays from the measurement surface to the detection element, (2) controlling the distribution and intensity of infrared rays through total internal reflection, and (3) correcting temperature measurement accuracy through its structural design. This multi-functionality reduces overall device complexity.
3Measurement precision
If the visual field area of the sensor case is reduced to eliminate temperature shift, then temperature detection accuracy is improved, but measurement range and adaptability are reduced
Solution Approach 1:
The patent applies local quality control through the light guide part's internal structure, which selectively processes infrared rays based on their origin and angle. The light guide part's geometric design creates different optical paths for different regions of the measurement field, enabling accurate temperature correction while preserving the full visual field area and measurement range.
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 solution allows for precise correction of detected temperature while maintaining high responsiveness and reducing the workload and cost, as the correction region is formed on the irradiation surface without adding mechanical elements, thus adapting to both increasing and decreasing temperature corrections.
Implementation Method 1
a heat conversion film configured to be irradiated with the infrared rays radiated from the detection object and to convert the incident infrared rays into heat
Implementation Method 2
a blocking part disposed facing the heat conversion film, and configured to block the infrared rays radiated from the detection object, from being incident on a part of the heat conversion film
Implementation Method 3
a light guide part including an irradiation surface and configured to guide the infrared rays radiated from the detection object to the region where the infrared detection element is provided
Data Source
AI summary
To provide an infrared temperature sensor that is corrected in detected temperature while ensuring high responsiveness. An infrared temperature sensor 10 according to the present invention includes a heat conversion film 40, an infrared detection element 43 held by the heat conversion film 40, a temperature compensation element 45 that is provided adjacently to the infrared detection element 43 and is held by the heat conversion film 40, a light guide part 59 that guides entered infrared rays toward the infrared detection element 43, and a blocking part 27 that blocks the infrared rays from being incident on the temperature compensation element 45, in which an inner surface of the light guide part 59 configures an irradiation surface 57 to be irradiated with the infrared rays, and the irradiation surface 57 includes a correction region 58 that is different in emissivity of the infrared rays from surroundings.