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What is a ToF sensor, how it works and on which smartphones it is present

What is a ToF sensor, how it works and on which smartphones it is present

In the panorama of current smartphones, among the parameters that most interest users, and which often play a prominent role in the evaluation and final choice of the device, we find the photographic sector. Over the years we have been used to seeing and reading increasingly in-depth analyzes of photographic sectors, within which we have begun to hear sensors more and more frequently. Time of Flight (ToF).

In the next few paragraphs we will understand how exactly a ToF sensor and why it is called that. This component is of particular importance due to its widespread presence in the smartphone landscape, even if its use is also extended to other technological sectors where there are independent ToF cameras that can work connected to different peripherals.


ToF sensor operation

From a technical point of view, i ToF sensors they base their functioning on the infrared light. Their name, time of flight – flight time, corresponds to the foundation of their operation. In fact, the ToF camera sends an infrared light signal towards the object to be mapped, this is reflected and returns to the sensor itself. Based on the time taken to go back from the infrared beam, ie the time in which the light beam was “in flight”, it is possible to calculate the distance of the object from the camera.

The above describes in a simplified way the operation of a ToF sensor. Basically we can compare it to the operation of ultrasonic fingerprint sensors, which are equally widespread in the smartphone sector. In this case, the variable that comes into play is the flight time of the signal under consideration, while for the fingerprint sensors it is the geometric parameters of the reflected or refracted sound waves.

In the case of ToF cameras, the time of flight allows for calculate the distance to the object framed by the sensor. This implies that the computational and technical strength of ToF sensors is the sensitivity of the time-of-flight calculator. The speed of the infrared light remains constant, the only variable to be derived is the distance traveled starting from the time elapsed from the emission to the reception of the infrared light beam.

Use of ToF sensors

ToF sensors are therefore very suitable for different types of use: Being able to accurately calculate the distance of an object from the camera is useful for shooting in mode bokehbecause you can understand which are the elements to blur more or less, make one focus more accurate especially in low light conditions, because the one based on the transduction of infrared light is independent of the ambient light, and also to achieve the Facial recognition or objects in three dimensions.

Therefore, ToF sensors not only improve the photographic compartments of smartphones but can also play a fundamental role in terms of safetybecause they can be integrated to achieve facial recognition in three dimensions which is known to be safer than that made in two dimensions.

Another use of ToF cameras on mobile devices involves applications in augmented reality and in virtual reality, especially in terms of object mapping.

ToF sensors are not only found in the smartphone world but also in the one related to car. In fact, self-driving cars require a massive use of ToF sensors to map the surrounding environment in near real time and recognize the objects surrounding the car.

Smartphone with ToF camera

Time-of-flight cameras are found on several smartphone currently circulating on the market. So let’s go see the small history of the integration of this type of sensors in the mobile devices we use every day. We specify that this is a history that includes only some of the main models with ToF sensors that we have seen on the market in recent years: