Iphone Sensors

IPHONE X SENSORS MENG-304 Mechanical Measurements Assignment 1 Name: Mohamed Ahmed Nabil Abdullah ID:1610727

Table of Contents Introduction: .................................................................................................................................. 2 List of Sensors in iPhone:.............................................................................................................. 3 -Proximity Sensor: .................................................................................................................................. 3 -Accelerometer/Motion sensor:.............................................................................................................. 4 -Ambient Light sensor: ........................................................................................................................... 5 -Moisture sensor: .................................................................................................................................... 5 -Gyroscope:.............................................................................................................................................. 6 -Compass: ................................................................................................................................................ 6 -Barometer: ............................................................................................................................................. 7 -Touch ID: ............................................................................................................................................... 7 -Face ID: .................................................................................................................................................. 7

References: ..................................................................................................................................... 8

Introduction: The iPhone, iPad, and iPod touch are able to perform some of their coolest interface tricks from dimming a phone screen when it's held up to your head to undoing an action by shaking the device and beyond. All of that are already done thanks to the sensors built into most models of those devices. Without these sensors, none of the devices would be what we know them as today. Mainly, not every model of the iPhone, iPad, or iPod touch has the exact same set of sensors, and the capabilities the sensors enable on each model has as much to do with the operating system being used as the hardware itself. Each year Apple releases nearly 2 versions of iPhone with different specifications and more improvements. Last year’s iPhone X was a massive leap forward in design for Apple after years of resting on its laurels. The iPhone X is intended to showcase what Apple considers technology of the future, specifically adopting OLED screen technology for the first time in iPhone history, as well as using a glass and stainless-steel form factor, offering wireless charging, and removing the home. iPhone X is a promising move in smartphones world as it introduce a new type password authentication called Face ID which depends on different sensors that will be discussed in addition to the sensor included in any kind of iPhone.

List of Sensors in iPhone: 1- Proximity sensor 2- Accelerometer/Motion sensor 3- Ambient Light sensor 4- Moisture sensor 5- Gyroscope 6- Compass 7- Barometer 8- Touch ID (Not included in iPhone X) 9- Face ID (Only included in iPhone X)

-Proximity Sensor: This sensor determines how close the iPhone is to your face. It's what helps the iPhone turn off its screen automatically whenever you hold the phone up to your ear for a phone call. This feature is necessary to prevent accidental button taps on the side of your head when talking. Figure 1: Proximity Sensor Operating Principles: There are three different types and detection principles of proximity sensors as follow: Inductive Proximity Sensors, Capacitive Proximity Sensors and Magnetic Proximity Sensors.

Inductive Proximity Sensor: It detects magnetic loss due to eddy currents that are generated on a conductive surface by an external magnetic field. An AC magnetic field is generated on the detection coil, and changes in the impedance due to eddy currents generated on a metallic object are Figure 2: Inductive Proximity Sensor detected. Capacitive Proximity Sensor: It detects changes in the capacitance between the sensing object and the Sensor. The amount of capacitance varies depending on the size and distance of the sensing object. An ordinary Capacitive Proximity Sensor is similar to a capacitor with two

Figure 3: Capacitive Proximity Sensor

parallel plates, where the capacity of the two plates is detected. One of the plates is the object being measured and the other is the Sensor's sensing surface. The changes in the capacity generated between these two poles are detected. Magnetic Proximity Sensors: The reed end of the switch is operated by a magnet. When the reed switch is turned ON, the Sensor is turned ON.

-Accelerometer/Motion sensor:

Figure 4: Magnetic Proximity Sensor

This sensor enables the iPod touch, iPad, or iPhone’s screen to automatically switch from landscape to portrait modes and back again based on whether you’re holding the phone vertically or horizontally. It is also responsible for sensing iPhone’s motion. Principle of Operating: Most accelerometers are Micro-ElectroMechanical Sensors (MEMS). The basic principle of operation behind

Figure 5: Accelerometer/Motion sensor

the MEMS accelerometer is the displacement of a small proof mass etched into the silicon surface of the integrated circuit and suspended by small beams. Consistent with Newton's second law of motion (F = ma), as an acceleration is applied to the device, a force develops which displaces the mass. Types of Accelerometers:

1- Capacitive: Accelerometers that implement capacitive sensing output a voltage dependent on the distance between two planar surfaces. 2- Piezoelectric: Piezoelectric sensing of acceleration is natural, as acceleration is directly proportional to force. When certain types of crystal are compressed, charges of opposite polarity accumulate on opposite sides of the crystal.

-Ambient Light sensor: This determines how much light is available in the area surrounding the iPhone, iPod touch, and iPad and automatically adjusts the brightness of the screen in order to conserve battery life and to calibrate the screen to ease eye strain. Figure 6: Ambient It is a photodetector that is used to sense the amount of ambient light present, and Light sensor

appropriately dim the device's screen to match it. This avoids having the screen be too bright when the user's pupils are adapted for vision in a dark room, or too dim when the device is used outdoors in the daytime. Dimming the screen on a mobile device also prolongs the lifetime of the battery.

-Moisture sensor: All of these devices contain this sensor, though it's not visible in the onscreen interface or accessible through the iOS. The moisture (or water) sensor is a little red tab that appears in the Dock Connector after the phone has been submerged in water. It can also appear as a red dot in the headphone jack, depending on the model. Moisture sensors are commonly used to take soil moisture

Figure 7: Moisture sensor

measurements. One method to help prevent a malfunction with the iPhone following its immersion into water may be to envelope the moisture sensor in a conductive glue to behave as an insulating layer. The idea here is for the device to detect the speed at which the conductive glue is eroded by water molecules.

-Gyroscope: Starting with the iPhone 4, 4th Gen. iPod touch, and iPad 2 there's another sensor: a three-axis gyroscope. When combining the gyroscope with the accelerometer, this combo gives these devices six axes on which it can operate. This is designed to make the devices more sensitive, responsive and powerful for gaming, allowing them to react based on how the devices are held and moved.

Figure 8: Gyroscope sensor

Gyroscope sensors sense angular velocity when it’s applied with external torques or rotations about the given axis, the orientation can be measured by a precession phenomenon. When an object rotating about an axis is applied with external torque along a direction perpendicular to the rotational axis, the precession occurs.

-Compass: All iPhone models starting with the iPhone 3GS also have a compass built into them. This sensor is used with the device's GPS and other location awareness features to help determine your iPhone's location, which direction it's facing, and to get you where you're going. Figure 9: Compass sensor

The working principle of digital compass is called " magneto-inductive" and is the largest advancement in compass technology since the fluxgate was invented 60 years ago. The magneto-inductive technology is able to electronically sense the difference in the earth's magnetic field from a disturbance caused by external elements such as ferro-magnetic materials and the magnetic field generated by automobile electrical systems. Most digital compasses have an embedded micro controller that subtracts the automobile magnetic field (the distortion) from the stronger earth magnetic fields resulting in a highly accurate compass reading.

-Barometer: Barometers assess air pressure to help, in part, to determine altitude. This sensor is used for location and directions features: It can help determine the more precise location of your device.

Figure 10: Barometer sensor

-Touch ID: A thumbprint sensor embedded in the Home button lets you secure access to your device with your biometric data. It can also be used to authorize purchases and to unlock apps. Figure 11: Fingerprint sensor

-Face ID: Introduced with the iPhone X, Face ID uses a complex system to identify a person's face to provide secure authentication to both the device and to services including Apple Pay.

How it works:

Figure 12: Face ID Recognition

As figure 13 below shows, a number of sensors integrated into a small space at the top of the iPhone X screen are: an infrared camera, flood illuminator, proximity sensor, ambient light sensor, front camera, dot projector, speaker and microphone. 3D sensing in iPhone X starts at the ToF (time of flight) sensor. Describing ToF as “more or less a presence detector,” It’s explained that ToF powers up the other sensors, once it detects motion. Next comes a structured light, which calculates the depth and surface information of the objects in the scene.

Figure 12: Face ID Integrated Sensors

References: 1-https://www.eetimes.com/document.asp?doc_id=1333597 2-https://www.lifewire.com/sensors-that-make-iphone-so-cool-2000370 3-https://support.apple.com/kb/SP770?locale=en_US 4-https://www.digitaltrends.com/mobile/apple-iphone-x-news/ 5-https://www.eetimes.com/document.asp?doc_id=1332274&page_number=1 6-http://techinsights.com/about-techinsights/overview/blog/apple-iphone-xs-teardown/ 7-http://www.ia.omron.com/support/guide/41/introduction.html 8-http://www.sensorwiki.org/doku.php/sensors/accelerometer 9-https://www.pc-control.co.uk/accelerometers.htm 10-https://www.explainthatstuff.com/accelerometers.html 11-https://www.azosensors.com/article.aspx?ArticleID=66

12-https://www.azosensors.com/article.aspx?ArticleID=252 13-https://www.safety-devices.com/how-does-digital-compass-work-a-12.html