4.5 PICK DEVICES

Pick devices are used to select an object on the screen. The selected object can be text or graphics. Examples of pick devices are light pens and touch screens.

4.5.1 Light Pens 

A Light pen is a pen like light-sensitive device. It is connected by a wire to the computer terminal to detect the CRT beam when pointed towards the screen and generate a narrow electrical pulse that can be fed to the computer as an input signal. It is used to draw on the screen or to point to the displayed objects. It operates by detecting the light emitted by the screen phosphors.

A light pen can work with any CRT monitor but not with LCD monitors. It is used by architects and engineers for CAD applications and editing.
 

4.5.2 Touch Screens

Touch screens are monitors / electronic visual display screens which detect where they are being touched. The user makes selections by directly touching the screen, rather than moving a cursor to the point on the screen with a mouse or joystick Now days touch screens are being used in ATM machines for making it user friendly and Kiosk machines are used for guiding the travelers about their travel plans. Touch screens are also used in many of the modern cell phones.