SENSORS & SENSING SYSTEMS FEATURE
Figure 1: In a complex cabinet like this it isn’t possible to measure temperature directly
EVERY TEMPERATURE TELLS A STORY
Gabriele Fulco, European product marketing manager, Omron Electronic Components, discusses the growth of contactless temperature measurement on the IoT
be interpreted by the system. A key advantage of the integrated
T
emperature is a parameter that can tell a story. Abnormal temperatures
are often the first sign of wear and tear, electrical faults and other issues; and they can warn of a potential fire before it actually starts. Temperature measurements can detect the presence or absence of people, or to confirm that a system is operational. That’s all in addition to the direct role of temperature measurement in controlling ovens and heaters. Very often, it isn’t possible to measure
temperature directly, by attaching a probe (Figure 1), so contactless temperature sensors are useful. From the detection of abnormal temperatures in industrial equipment on the production line to monitoring food and other temperatures in the kitchen, contactless sensors like the MEMS-based Omron D6T make a valuable contribution to safety – identifying potential problems before they become major hazards. This can not only save lives but also costs, allowing preventative maintenance to be undertaken in a timely manner.
ADVANTAGES OF INTEGRATED SIGNAL PROCESSING Omron D6T MEMS thermal sensors are based on an IR sensor which measures the surface temperature of objects without touching them using a thermopile element that absorbs radiated energy from the target object. Incorporating a state-of-the-art MEMS thermopile, custom designed sensor ASIC and signal processing microprocessor and algorithm into a tiny package, the D6T is believed to offer the highest signal-to-noise ratio (SNR) in the industry. This ensure clear, reliable measurements that can readily
signal processing microprocessor is the fully linear output (Figure 2). By pre-processing the signal on the module, the D6T converts the sensor signal to a digital temperature output, giving a straightforward interface to a microcontroller, simplifying the system integrator’s task. Alternative devices don’t provide a temperature output, so the designer needs to implement a signal processing algorithm to convert the output to temperature. Despite the inclusion of the
microprocessor, Omron has achieved a space saving design for the D6T. At only 14 x 8 x 8.93mm for the largest 32 x 32 element version, it is exceptionally well suited to temperature detection in a wide range of Internet of Things (IoT) and other embedded applications.
Figure 2: Omron’s D6T outputs temperature directly, as opposed to devices that require signal processing
(81cm x 84cm) respectively. Contactless sensors can be applied to
a whole range of different environments. Depending on the requirement, temperature bands of 5 to 45˚C, -40 to +80˚C, 0 to 200˚C can be specified.
“Temperature measurement is a
growing issue as more and more systems are connected to
SELECTING A CONTACTLESS SENSOR In addition to the temperature range, the key parameter in selecting a contactless sensor is the field of view. Often, manufacturers create a wider field of view by combining multiple individual sensor elements into a module. This, however, isn’t always desirable – sometimes a targeted measurement of a specific object or area is required. For example, the single element Omron
temperature monitoring devices are growing in sophistication...”
D6T-1A-02 has a viewing angle of just 26.5˚ x 26.5˚, translating to an area of 47 x 47cm at a distance of 1m, giving a highly directional characteristic. By contrast, the latest addition to the range, the 32 x 32 element D6T-32L-01A (Figure 3) can view across 90.0˚ by 90.0˚. At 1m, this translates to an area of 200 x 200cm, and this sensor is able to encompass a wide area such as a whole room from a single point. Applications where a more restricted field of view is needed can be fulfilled by the 1x8 D6T-8L-09H and the 4x4 D6T-44L-06H, offering 54.5˚ x 5.5˚ (103cm x 10cm) and 44.2˚ by 45.7˚
/ DESIGNSOLUTIONS
Figure 3: Omron D6T 32x32 MEMS contactless temperature sensor can measure temperatures up to 200˚C over a very wide field of view
the IoT and expected to operate remotely. Contactless
MEETING IOT DEMANDS Temperature measurement is a growing issue as more and more systems are connected to the IoT and expected to operate remotely. Contactless temperature monitoring devices are growing in sophistication as the technology develops. With a wide range of field of view characteristics and a choice of thermal profile, there is
now a solution for a great many industrial monitoring applications. Devices with direct, linear
temperature, outputs make system integration particularly straightforward. This is definitely the technology of the future for temperature monitoring on the IoT.
Omron Electronic Components
http://components.omron.eu
DESIGN SOLUTIONS | MARCH 2020
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