Hardware
Screen and input
The touchscreen on the first five generations is a 9 cm (3.5 in) liquid crystal display with scratch-resistant glass, while the one on the iPhone 5 is 4 inches.[7] The capacitive touchscreen is designed for a bare finger, or multiple fingers for multi-touch sensing. The screens on the first three generations have a resolution of 320×480 (HVGA) at 163 ppi; those on the iPhone 4 and iPhone 4S have a resolution of 640×960 at 326 ppi, and theiPhone 5, 640×1136 at 326 ppi. All iPhones were and still are equipped with LCDs. The initial models were using twisted-nematic (TN) LCDs. Starting with iPhone 4, the technology was changed to in-plane switching (IPS) LCDs. The iPhone 5 model's screen results in an aspect ratio of approximately 16:9.
The touch and gesture features of the iPhone are based on technology originally developed by FingerWorks.[94] Most gloves and styli prevent the necessary electrical conductivity;[95][96][97][98] although capacitive styli can be used with iPhone's finger-touch screen. The iPhone 3GS and later also feature a fingerprint-resistant oleophobic coating.[99]
The iPhone has a minimal hardware user interface, featuring five buttons. The only physical menu button is situated directly below the display, and is called the "Home button" because it closes the active app and navigates to the home screen of the interface. The home button is denoted not by a house, as on many other similar devices, but a rounded square, reminiscent of the shape of icons on the home screen.
A multifunction sleep/wake button is located on the top of the device. It serves as the unit's power button, and also controls phone calls. When a call is received, pressing the sleep/wake button once silences the ringtone, and when pressed twice transfers the call to voicemail. Situated on the left spine are the volume adjustment controls. The iPhone 4 has two separate circular buttons to increase and decrease the volume; all earlier models house two switches under a single plastic panel, known as a rocker switch, which could reasonably be counted as either one or two buttons.
Directly above the volume controls is a ring/silent switch that when engaged mutes telephone ringing, alert sounds from new & sent emails, text messages, and other push notifications, camera shutter sounds, Voice Memo sound effects, phone lock/unlock sounds, keyboard clicks, and spoken autocorrections. This switch does not mute alarm sounds from the Clock application, and in some countries or regions it will not mute the camera shutter or Voice Memo sound effects.[100] All buttons except Home were made of plastic on the original first generation iPhone and metal on all later models. The touchscreen furnishes the remainder of the user interface.
A software update in January 2008[101] allowed the first-generation iPhone to use cell tower and Wi-Fi network locations trilateration,[102] despite lacking GPS hardware. Since the iPhone 3G generation, the smartphone employA-GPS operated by the United States. Since the iPhone 4S generation the device also supports the GLONASS global positioning system, which is operated by Russia.Russia
