Mouse

Mouse

             What is probably the most amazing thing about a PC mouse took so long to become a standard part of the PC's equipment. It is perfectly natural for a user to point at objects on the display instead of typing in a command, and many attempts were made to develop such a tool for the PC. Light pens, touch screens, graphics tablets, and joysticks, among other devices, were all tried, but none satisfied the user as a workable, intuitive pointing device. The mouse was introduced with the Apple Macintosh and was an immediate success. The mouse was the natural, intuitive, inexpensive pointing device users wanted. But, it wasn't untill the early 1980s, when Windows and its graphical user interface (GUI) was released, that the PC had an operating system that could work with the mouse. Since the time, the mouse has become a standard equipment on virtually all PCs. There are three types of mouse units used with PCs.

•  Mechanical mouse:  This is the older style of mouse used with early Macintosh and PC GUI systems. In a mechanical mouse, the movement of a rubber ball causes a pair of wheels to spin that sensors detect to send data signals to the PC.
•  Opto-mechnical mouse This type of mouse uses light-emitting diodes (LEDs) to sense mouse movements. This is the most common type of mouse used with PCs today.
• Optical mouse: The optical mouse eliminates the use of mechanical devices (balls, rollers, and wheels) and uses optical scanning to detect the movement of the mouse over virtually any surface.
• Glidepoint Mouse: Glidepoint mouse predominantly found on notebook PCs, but there are a few keyboards available that include this type of pointing device. A glidepoint mouse is the pivoting rubber-tipped device that looks like an eraser tip and is located between the G and dthe H keys on a notebook PC keyboard.

Inside the Mouse

            A mouse translates the motion of the user's hand into electrical signals that the PC uses to track a pointer across the monitor's display. To capture the motion of the user's hand, an optomechanical mouse uses six privary components:

• Ball: The ball is the largest and central part of the mouse. When the user grasps the mouse and moves it over a mouse pad or the desktop, the ball rolls inside the mouse.
•  Rollers: As the ball rolls inside the mouse, two rollers that touch the ball track its rotation side to side and up and back.
• Roller shafts: The rollers are each connected to a shaft; as the rollers turn in conjunction with the ball, each shaft turns an optical encoding disk that is attached to it.
• Optical encoding disk: As the ball rolls, the rollers turn the shafts that spin the optical encoding disks. The optical encoding disk has 36 holes along its outside edge.
•  Infrared LED and sensor: On one side of each optical encoding disk is a light-emitting diode (LED) that shines an infrared light beam on the disk. On the other side of the disk is a light-sensitive transistor that serves as an infrared sensor. As the disk turns, the disk turns, the solid areas between the holes on the disk break the LED's infrared beam and the infrared sensor sees pulses of light. The rate and  duration of the light pulses indicate the speed and distance of the mouse's travel.
•  Processor: The mouse has a processor that reads the pulses sent from the infrared sensors and converts them into binary data, which is sent to the PC's interface over the mouse's connecting cord.
•  Buttons: The mouse also has one, two, three, or more buttons (two is the most common number of buttons on PC mice) that are connected to small switches that also connect to the mouse's processor. As the user clicks the buttons to select an objecct on the screen or start a program or applet, the processor converts the clicks into binary data that is sent to the PC. Windows systems use tow-button mice, Macintosh systems have gotten by very nicely with a single mouse button, and UNIX and Linux systems have functions that require the use of a third mouse button. Mice that have buttons on tap as well as on the side and elsewhere require special software device drivers to enable the function of these buttons.

Mouse Connectors

           Nearly all mice sold today have a six-pin mini-DIN (PS/2) connector. This connector, which was first introduced with the IBM PS/2 system, has essentially replaced the DB-9 serial connector that was used before that. Serial mice are still available, but since newer PC systems rarely offer more than a single serial port and include PS/2 connectors for both the keyboard and mouse, the serial mouse has all but disappeard.

            The PS/2 connector on the mouse uses four pins to connect and communicate to the PC. The mouse sends data and clocking signals to the PC using very much the same techniques as the keyboared. A mouse uses pins in the connector and wires in the cable for +5V power (pin 2), the clocking signal (pin 4), a ground (pin 5), and a data signal (pin 6). The power connection supplies +5V of electricity to the processor and LEDs. Mice are now available with USB, infrared (IrDA), and radio frequency (RF) connections as well. The USB connector is becoming a popular choice among notebook PC users who wish to connect an external keyboard into a botebook's single PS/2 connection and still use an external mouse. Cordless mice communicate with a PC through either an infrared or an RF receiver.

   

           Many PCs now come with an IrDA receiver included, but RF connections require an external receiver. External RF and infrared receivers can also be added to a PC through a PS/2 or USB port. An optomechanical mouse gets its power (+5V) from the PC over its interface cable, cut cordless mice do not have a power connection and , regardless of the type of connection in use, run on a pair of AAA batteries.

           Infrared connections are line of sight and have a limited effective operating distance. The infrared connection must have a clear, unobstructed line of sight to the receiver, which must be in a clear, open location; a radio frequency connection doesn't require a line of sight.

Types of Mouses

Wheel Mouse

           A newer version of the standard opto-mechanical mouse is the wheel mouse. The wheel mouse has a finger wheel located on its top, typically between the two buttons. The wheel allows the user to scroll forward and backward through a document in place of clicking on a window's scroll bar or using the PAGE UP and PAGE DOWN keys or the cursor control arrow keys.

Optical Mouse

            The optical mouse eliminates the mouse ball, replacing it with a optical sensors that track the movement of the mouse against the background of the mouse pad or whichever flat surface it's on. Optical mice have been around for a few years. The older design for the optical mouse required a highly reflective mouse pad that had a printed grid on it. The real drawback to his mouse, required a highly reflective mouse pad that had a printed grid on it. The real drawback to this mouse, besides the fact it was slow, was that if you lost the mouse pad, the mouse would not work on a normal flat service that had a bit or texture or detail to it. Some surfaces, such as glass, mirrors, or smooth, shiny, solid-color surfaces without detail, do not work well with even the new optical mice.

            The latest optical mouse designs include an optical process that captures images of the surface underneath the mouse at a rate of up-to 2,000 images per second. The mouse includes a digital signal processor (DSP) that analyzes these images and is able to detect even the slightest movement. The optical system of the mouse eliminates the need for fa mouse pad and works on virtually any flat surface except those that are very shiny or reflective. One real advantage to the optical mouse over the opto-mechanical mouse is that it does not require internal cleaning.

Touch pads

           A touchpad is a fixed-place pointing device that has become very common in notebook computers. A touchpad is a small, flat square or rectangular surface on which you slide (touch) your finger to move the cursor on the display, select objects, and run programs. A touchpad provides the same actions as a mouse.

Trackballs

          A trackball is essentially an upside-down mouse. A trackball is a mouse-like tool that has two or more buttons and a ball on top of the device. The ball, which can be located on the top or side of the trackball, is manipulated with either a thumb or finger to move the cursor on the screen. A trackball, which can be either a corded or cordless device uses essentially the same technology asd an opto-mechanical mouse to communicate its movements to the PC and connects through the PS/2 and USB connections.

Jovsticks

        A joystick is a type of pointing device that is used primarily with game software on a PC. A joystick consists of a handle that is connected to a yake inside its base. The yoke is set on a pivoting mechanism that allows the joystick to move in any direction from a center point.

         Most joysticks attach to a game port located on a game, video, or sound card, but many new models also support a USB connection as well. A software device driver then interprets the data signals sent from the joystick and transfers the actions onto  the screen. Some joysticks are force-feedback devices that simulate pressure and forces on the joystick to make the game more realistic, like the 3D joystick.