Temperature Sensor With Infrared Absorber and Heat-Transfer Inhibitor

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Solution Overview

Problem

Existing temperature sensors in image forming apparatuses, such as printers, face challenges in accurately measuring temperatures due to exposure to infrared rays from both sides, which can cause heat transfer and reduce the temperature difference between detection and compensation thermistors, affecting measurement accuracy.

Innovation Solution

The implementation of a temperature sensor design that includes a first temperature-sensitive element, a second temperature-sensitive element, an infrared-ray absorber, and a heat-transfer inhibitor. The infrared-ray absorber absorbs infrared rays and transfers heat to the first element, while the heat-transfer inhibitor minimizes heat transfer to the second element, enhancing the temperature difference and measurement accuracy by using infrared-ray reflection films and cover members with specific emissivity and thickness to control infrared radiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If the temperature sensor is exposed to infrared rays from both front and back surfaces, then the sensor can detect temperature from both sides, but the infrared rays cause heat transfer that reduces the temperature difference between detection and compensation thermistors, degrading measurement accuracy

Engineering Contradiction:

Improvebilateral temperature detection capabilityVSAvoidtemperature measurement accuracy

Core Design Contradiction:

Adaptability or versatilityVSMeasurement precision

Solution Approach 1:

The sensor structure is segmented into distinct functional zones: the front surface contains the detection thermistor with infrared absorber for active temperature detection, while the back surface contains the compensation thermistor with infrared reflector for environmental compensation. This segmentation allows each thermistor to serve its specific function without interference from infrared rays, resolving the contradiction between bilateral detection capability and measurement accuracy.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the sensor have different optical properties: the front surface region has high infrared absorption to maximize temperature detection sensitivity, while the back surface region has high infrared reflection to minimize heat transfer to the compensation thermistor. This local differentiation of optical quality allows the sensor to maintain measurement accuracy while preserving bilateral detection capability.

Inventive Principle:

Principle #3Local quality

2Measurement precision

If infrared-ray absorbers are added to enhance temperature detection, then the temperature sensitivity improves, but the device structure becomes more complex

Engineering Contradiction:

Improvetemperature detection sensitivityVSAvoidsensor structure complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The infrared absorber and reflector are merged with the substrate structure itself rather than being separate components. The substrate is designed with specific optical properties and structural features that serve both as the mechanical support and as the infrared management element. This merging reduces the number of discrete parts while maintaining the temperature sensitivity enhancement.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The substrate serves multiple functions simultaneously: it provides mechanical support for the thermistors, acts as the infrared absorber on the front surface, serves as the infrared reflector on the back surface, and provides thermal isolation. This multi-functionality reduces the need for additional components, thereby limiting the increase in device complexity while improving temperature detection sensitivity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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

This design improves temperature measurement accuracy by maintaining a larger temperature difference between the detection and compensation thermistors, enabling more precise temperature monitoring of heating elements in image forming devices.

Implementation Method 1

the infrared absorber heats up by absorbing the infrared rays and transfers heat to the first temperature-sensitive element

Methodology Applied

Scientific EffectInfrared absorption: Absorption (EM radiation)

Implementation Method 2

the heat-transfer inhibiter inhibits heat transfer to the second temperature-sensitive element caused by the infrared rays

Methodology Applied

Scientific EffectInfrared reflection: Reflection

Data Source

PatentUS9163999B2Temperature sensor, fixing device, and image forming apparatus

Publication Date: 2015.10.20 FUJIFILM BUSINESS INNOVATION CORP

AI summary

A temperature sensor includes a front surface; a back surface; a first temperature-sensitive element and a second temperature-sensitive element disposed side by side between the front surface and the back surface; an infrared-ray absorber; and a heat-transfer inhibitor. When the temperature sensor is exposed to infrared rays that have propagated from both of a front-surface side and a back-surface side of the temperature sensor, the infrared absorber heats up by absorbing the infrared rays and transfers heat to the first temperature-sensitive element and the heat-transfer inhibiter inhibits heat transfer to the second temperature-sensitive element caused by the infrared rays.