Embedded Technology

Table 1. The D6T family includes sensors from single-pixel to multi-pixel devices

high signal to noise ratio (SNR). The result is a compact device that is well suited to embedded applications and relieves key signal-processing workloads from the system host processor. D6T sensors can be added to an access-control system, for example, to automatically check the temperature of a visitor on arrival (figure 1).

Sensor Family for Versatile Monitoring

The family of D6T far-infrared sensors brings the advantages of continuous non-contact temperature measurement to a variety of applications, particularly accurate occupancy and proximity sensing.

The D6T family offers sensors in a variety of sizes from single-pixel sensors to devices with 4x4 and 32x32 pixel arrays (see table 1), and with different viewing angles, to address numerous applications in building automation, energy management, security, industrial, predictive maintenance and safety. The 4x4 and 32x32 pixel array sensors are well suited to body-temperature sensing applications.

Accurate Body-Temperature Measurement

The typical accuracy of D6T sensors, as supplied, is ±1.5°C. To use these devices in a precision body-temperature monitoring

Figure 4. Calibrating with reference temperatures

context such as coronavirus infection checking an accuracy of ±0.2°C is ideally required, this means additional custom calibration is recommended for increased accuracy. An effective way to calibrate the sensor is to start by setting both the upper target temp (y0) and the lower target temp (y1) to cover a suitable range. For an access-control system, designed to assess the surface temperature of a human face, a typical range could be from about 32°C to 38°C. To calculate a correction factor and thus ensure accurate temperature measurement with D6T sensors, a calibration source such as a blackbody furnace can be used (figure 4). The source is set first to the lower limit temperature (let’s call it y0) and measured with the D6T. We recommend recording, say, 10 measurements to get an average sensor output reading (x0), making sure first to allow about 15 minutes for the system to stabilise after powering on. The source is then set to the upper maximum temperature (y1), and the average of a second set of sensor readings (x1) taken in the same way as before.

Using the reference source settings and recorded temperature measurements, the calibrated target object temperature, y, for any given sensor output reading, x, can be calculated using this formula:

Figure 1. Accurate non-contact temperature measure- ment for access control and protection

Thanks to the integrated signal-processing ASIC, D6T sensors output the digital temperature value via an I2C interface that the host system can read directly. The sensor comes mounted on

Components in Electronics

a PCB with terminations provided, allowing easy integration into the end application. Omron have many years of experience in contactless temperature measurement and can provide guidance and advice to designers on how to get the accuracy of the D6T down to the ±0.2°C required for effective human body temperature checking.

Access Control and More

Anglia can supply the full range of Omron B5W light convergent reflective photo sensors, W7ED capacitive touch sensors, and D6T non-contact temperature sensors for future generations of automated devices designed to further improve safety and help prevent the spread of disease. Samples and evaluation tools are available free of charge to registered account customers within EZYsample. Anglia field application engineers are trained and ready to help you select the right sensors for your needs and take full advantage of their superior features in your next project.

Visit or scan the QR code to discover more about these sensors and other Omron products available from Anglia.

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