“If you are already a parent, you may have done something like this when the baby was just born – the baby was sleeping and looked motionless, and you would probe the baby’s nose with your hand to see if the baby was breathing normally, You can feel at ease when you have warm breathing air on your hands. This behavior is commonly referred to as “new parent anxiety.” Today, this anxiety can be eliminated using ToF technology.A proof-of-concept design for health care products using ToF technology, jointly completed by Analog Devices, Arrow, the Chinese University of Hong Kong, etc., can easily measure the baby’s chest activity, calculate the respiratory rate, and transmit this information to the mobile phone.

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If you are already a parent, you may have done something like this when the baby was just born – the baby was sleeping and looked motionless, and you would probe the baby’s nose with your hand to see if the baby was breathing normally, You can feel at ease when you have warm breathing air on your hands. This behavior is commonly referred to as “new parent anxiety.” Today, this anxiety can be eliminated using ToF technology. The proof-of-concept design for health care products using ToF technology, jointly completed by Analog Devices, Arrow, and the Chinese University of Hong Kong, can easily measure the baby’s chest activity, calculate the respiratory rate, and transmit this information to the mobile device.

ToF cameras ease the anxiety of new parents

ToF technology is gaining traction for applications that require real-time depth mapping, with use cases including industrial safety and automation, autonomous driving, material detection and classification, virtual and augmented reality, and drones. Now, we are very happy to see the adoption of ToF technology in the field of consumer medical products. According to reports, ADI’s first proof-of-concept design for health care products uses ADI’s 3D ToF technology. Powered by smart sensing algorithms, the design demonstrates how 3D ToF technology can be deployed to provide high-precision, nanosecond-scale real-time sensing data for breathing pattern monitoring and micro-motion detection.

The monitor of this design uses ADI’s ToF technology camera at the front. As the baby breathes, the monitor transmits real-time data. These data pass through custom filters and enhanced algorithms, allowing the guardian to measure the baby’s chest activity. The mobile device will be based on The baby’s breathing rate refreshes this information in real time. In addition, for small-month-old babies, it is also dangerous to lie on their stomachs if they are not yet skilled in turning over. The monitor can also monitor whether the baby is turning over. This action can also be clearly seen in mobile devices. arrive.

Proof-of-Concept Design for Healthcare Products Using ToF Technology

It is reported that the concept design will be adopted by Hubble Connected, a provider of IoT technology and platform services for Motorola’s smart parenting brand. With this monitor product, new parents no longer need to get up in the middle of the night to probe their babies with their fingers. Snort or see if your baby rolls over, just pick up the mobile device at hand to see how your baby is doing.

Powerful ToF applications come from the depth information of every pixel

ToF is an emerging monitoring method with great potential. Powerful ToF applications come from depth information at every pixel: ToF cameras measure distance by actively illuminating an object with a modulated light source, such as a laser or LED, and then capturing the reflected light with a sensor sensitive to the laser wavelength. The sensor measures the time delay, ΔT, between the emission of light from the camera and the reception of the emitted light by the camera. The time delay is proportional to twice the distance (round-trip) between the camera and the object; therefore, the distance can be estimated as depth = cΔT/2, where c is the speed of light. The main job of a ToF camera is to estimate the delay between the emitted light signal and the reflected light signal. There are many different methods of measuring ΔT, of which the continuous wave method and the pulse are the two most commonly used methods.

Schematic diagram of a simple ToF measurement

The continuous wave method uses a periodically modulated signal to actively emit light, and then homodyne demodulates the received signal to measure the phase shift of the reflected light; in the pulsed method, the light source emits a series of N short laser pulses, which are reflected Back to a sensor with an Electronic shutter capable of taking exposures in a series of short time windows. Both ToF methods have their own advantages and disadvantages relative to the application. The ToF system that chooses which method to consider includes: measurement distance, the environment in which the system is used, accuracy requirements, thermal/power constraints, form factor, and power issues. . It is worth noting that the vast majority of continuous wave ToF systems that are widely used in the market today use CMOS sensors, while pulsed ToF systems use non-CMOS sensors (mainly CCDs).

High-performance analog front-end solves key technical challenges of ToF applications

ADI’s ToF technology is a pulsed ToF CCD system that uses a high-performance ToF CCD and integrates a 12-bit ADC, a depth processor (which processes raw analog image signals from the CCD into depth/pixel data), and a high-precision clock generator (for The TOF analog processing front-end ADDI9036 for CCD and laser generation drive timing). The timing generator’s precise timing core supports clock and LD output adjustments with approximately 174 ps resolution at a 45 MHz clock frequency.

ADI ToF System Functional Block Diagram

Compared with other solutions, ADI’s ToF system has the following advantages: First, it uses a ToF image sensor with a resolution of 640×480, which is 4 times higher than that of most other ToF solutions on the market; Second, a sensor that is highly sensitive to the 940nm wavelength is used.

We all know that ambient light can significantly reduce the signal-to-noise ratio of reflected signals, especially in strong ambient light. 940nm lasers have become commonplace because this wavelength occupies a place in the sunlight spectrum, where the magnitude of photon flux is relatively low. The ADI ToF system uses a ToF CCD that is sensitive to 940nm light, so it can collect more valid signals in outdoor environments or areas with strong ambient light. The image below shows an example where distances are measured outdoors using three different depth measurement systems. It is worth noting that a CMOS ToF system using an 850 nm light source has difficulty distinguishing a person from a tripod, while ADI’s CCD ToF system can clearly distinguish the two.

Comparison of depth maps for outdoor images

in conclusion

ToF sensor technology can precisely project controlled laser light lasting only a few nanoseconds, which is then reflected from the scene to a high-resolution image sensor, giving a depth estimate for each pixel in this image matrix. ToF cameras have become the preferred method for depth measurement due to their smaller form factor, wider dynamic sensing range, and ability to work in a variety of environments. ADI is designing, producing and selling a new product line that includes 3D ToF imagers, laser drivers, software and hardware-based depth systems that will provide the best depth resolution on the market with millimeter-level accuracy. In particular, CMOS ToF products based on Microsoft Azure Kinect technology will provide leading solutions for a wide range of audiences in Industry 4.0, automotive, gaming, augmented reality, computational photography and videography.