Thermopile temperature sensor is an optical sensor that detects temperature without contact. It absorbs infrared radiation emitted from humans or objects using a silicon device with MEMS structure, and measures the resulting temperature difference as a voltage using a thermopile (a combination of multiple thermoelectric couples) and calculates it as temperature information. We develop multiple products tailored to different applications such as human detection, high-temperature detection, and an array-type thermopile that integrates thermopiles and can detect temperature distribution in 2D.

Features

• It can detect the temperature of objects non-contactly.
• There is no need to consider the heat capacity of the measured object.
• Temperature detection is possible in a short period of time.
• It is hygienic because it is non-contact.

Infrared ray is radiated by heat sources such as the human body and objects. By measuring the energy of this infrared ray, it becomes possible to detect the temperature of the radiation source object. When an structure absorbs this infrared ray, it experiences a temperature increase. However, if infrared ray is uniformly absorbed, it becomes impossible to gather information from it. To address this issue, a structure is needed that prevents heat from dissipating and concentrates it on a specific area. First, the device structure was designed, using MEMS technology as shown in Fig 2(a), to create a structure where the receiving infrared ray part is suspended in the air by supports, ensuring that heat does not escape. Then, as shown in Fig 2(b), use a lens to irradiate infrared rays only to this area. This design allows only the light-receiving part to absorb the infrared ray and experience a temperature rise. In addition, it minimizes the transfer of heat to areas outside the light-receiving part, enabling the creation of a temperature difference between the light-receiving part and other components. Furthermore, by placing multiple thermal junctions of thermocouples in the formed light-receiving section, it becomes possible to amplify the potential difference generated by the very small temperature difference resulting from infrared absorption. This potential difference corresponds to the energy of the light source, and by performing calculations based on it, it is possible to measure the temperature of the target object.

In this section, we will describe several thermopiles developed by KODENSHI.

It is a thermopile sensor module using infrared thermopile which can measure temperature contactless. Since it is equipped with an environmental temperature compensation function, it is a sensor with small output fluctuations due to changes in environmental temperature. Additionally, its high reliability is attributed to the adoption of a CAN package enclosed in a metal can-shaped housing. For more detailed product information of infrared distance sensor, please click here.

Flat-type thermopile-type temperature sensor is a newly developed product. In conventional models, Si lenses are used to focus incident light onto the photodetector. The manufacturing of these lenses involves significant energy consumption and material waste through processes like cutting and polishing. However, in this new development, we have employed a unique reflector structure that allows light to be concentrated on the photodetector without the need for a lens. As a result, we have achieved energy efficiency, reduced material waste, and made it cost-effective.
This innovative product offers faster response times and superior temperature accuracy compared to thermistors. Therefore, it has the potential to open up new markets by improving performance in fields where thermistors have traditionally been used. Additionally, besides replacing existing thermopile-type temperature sensors, it can be applied to temperature measurement for non-contact body temperature measurement in various situations. We propose it as a high-precision, cost-effective, and environmentally friendly solution.

The chip of this sensor integrates multiple thermopiles, enabling the detection of temperature distribution of target objects and the shape of heat sources in two dimensions. This sensor finds applications in various fields such as human detection, people counting, human tracking, surveillance, security, as well as temperature distribution management in household appliances like microwave ovens and air conditioners. It is equipped with an integrated environmental temperature sensor and a CPU for temperature conversion, allowing it to provide temperature values as output. For more detailed product information of infrared distance sensor, please click here.

Thermopile temperature sensors are non-contact devices capable of detecting the temperature and temperature distribution of objects. They find various applications, such as temperature control within devices like printers and dryers, temperature measurement including body temperature, and functions like human detection, people counting, and human tracking. Additionally, they are used in surveillance and security applications, as well as temperature distribution management in household appliances like microwave ovens and air conditioners.