Lock screen

A lock screen is a user interface element used by various operating systems. They regulate immediate access to a device by requiring that the user perform a certain action in order to receive access, such as entering a password, using a certain button combination, or performing a certain gesture using a device's touchscreen. While most lock functions on PC operating systems only utilize a login screen, lock screens on mobile devices often provide more functionality beyond unlocking the phone: such as notifications for emails and text messages, a date and time display, or shortcuts to certain applications.

Operating systems that run on smartphones and tablets typically use a gesture-based lock-screen. Mobile phones manufactured by Neonode were unlocked by swiping to the right on its touchscreen. Apple's iOS, used by the iPhone and iPad lines, utilizes a similar unlock mechanism using an on-screen slider widget to the right. Beginning on iOS 5, sliding in the other direction sends the user directly to the camera app. On iOS 7, the slider widget was removed as part of a larger overhaul of the iOS interface, and users can now swipe from any point of the screen. The lock screen also displays a clock, notifications, and provides audio playback controls.

At first, Android did not use a gesture-based lock screen, electing to just require the user to press the phone's Menu button. On Android 2.0, a new gesture-based lock screen was introduced, displaying two icons: one for unlocking the phone, and one for setting the volume mode, activated by dragging the relevant icon to the center of the screen on a curve (similarly to a rotary dial). On Android 2.1, the rotary dial was replaced by two tabs on either end of the screen. Android 3.0 introduced a new design: a ball with a padlock icon is dragged to the outside of a circular area. On 4.0, the option to unlock straight to the camera is provided, while 4.1 adds the ability to unlock into a Google Search screen by dragging up. Android 4.2 makes additional changes to the lock screen, allowing users to add widgets to pages accessible on the lock screen by swiping from the left edge of the screen. The camera is accessed in a similar manner by swiping from the right edge of the screen. Android also allows devices to be locked using a password, a pattern on a grid of 9 circles, or with facial recognition.

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