mouse has a trackball that rotate in any COMPUTER MOUSE direction. Moving the mouse will cause the ball to rotate and this determines its directions. The A standard mouse consists of the following mouse uses two metal rollers that detect its components: horizontal and vertical movements. Connected to the end of the metal rollers are a disk-like Housing – the one you hold in your hand encoder wheels that rotate in between two and move around on your desktop optical beams. The signal of the beam will be Method of transmitting movement to the interrupted and this will generate the electrical system – can either be Ball/roller or signals. optical sensors Image from www.bristol.ac.uk Buttons – used for making selections Interface – connects the mouse to the system. Conventional mice use wire and connector while wireless mouse use radio frequency or infrared transceiver. Computer Mouse Development Computer mouse was invented by Douglas Engelbart of Stanford Research Center in 1964 and was originally called “X-Y Position Indicator” Shown above is a sample mechanical mouse with a for a display system. In 1973, Xerox used the track ball in the underside that makes contact with the same mouse design in its experimental working surface of the mouse. computer called “Alto”. In 1979, Steve Jobs The mouse ball can be removed by rotating the (owner of Apple/Macintosh) after seeing what a mouse ball housing in a counter clockwise direction. mouse can do in the “Alto computer”, decided to The mouse ball (rubber ball) rolls as you move the incorporate the mouse system together with the mouse. Its movements are translated into electrical signals transmitted to the computer across the cable. GUI (Graphical User Interface) to his latest computer design called “Lisa”. It was in 1984 when Apple introduces Macintosh as the 2. Optical Mouse – was developed in 1999 by mainstream of their computer design. Macintosh Agilent Technologies and it works like a tiny became a hit, and because of this the mouse camera that takes thousands of pictures every development was credited to Apple Computers. second. It is designed to work on every surface without the use of a mouse pad. It uses a LED (Light Emitting Diode) to transmit the light beam and a photodiode (sensor) to detect the movement relative to underlying surface. An optical mouse developed by Microsoft is shown above. It works by illuminating a LED on its underside Image from www.en.wikepedia.com and uses an optoelectronic sensor to detect relative motion on different types of surface. The first mouse design developed by Douglas Engelbart is shown above. It was made from wood and a metal wheel. Physically it looks very primitive, 3. Laser Mouse – was developed by Sun Micro but it works. system in 1998 and it works like an optical mouse, but it uses a small infrared laser instead of a LED. Using an infrared laser increases its tracking capability by 20 times as compared to Types of Mouse conventional mouse. The mouse sensitivity and 1. Mechanical Mouse – was invented in 1972 by Bill English while working with Xerox. The 1 resolution also increases but the power Mechanical mouse utilizes less power compared consumption decreases on this type of mouse. to an optical mouse, but this is not a serious issue for PC users. Users are more focus on the mouse efficiency. How Mechanical Mouse Works Mechanical mouse always depends on the rotation of the track ball in determining its speeds, directions and movements. The track ball is connected to two rollers which individually determine the X (horizontal)and Y (vertical) directional motion of the mouse. As shown Image from www.bbspot.com below each roller has its own chopper wheel (looks like a bicycle wheel) that interrupts the Shown above is a sample laser mouse developed by beam transmitted by light source and received Microsoft. Compared to optical mouse, laser mouse by the detector. The wheel passes in between has greater resolution because it uses infrared the light source and detector causing the light technology. beam to break. The break in the light beam is converted to electrical signal that correspond to Optical Mouse Versus Mechanical Mouse movement in the mouse pointer. Working surface Optical mouse can work on different landscape compared to a mechanical mouse. Its optical technology can accurately determine the movement, direction and speed of the mouse regardless of the contour in its working surface. Mechanical mouse will encounter problem once the working surface is bumpy (not smooth). However, optical mouse will have problem working in glossy and transparent surfaces. The light may not bounce back directly to the Shown below is the inside of a mechanical mouse. It optoelectronic sensor and this may cause the has the mouse circuitry, infrared LED and sensor, pointer to drift unpredictably during operation. mouse buttons, chopper wheel and the ball that touches the desktop and rolls when the mouse Life expectancy moves. Optical mouse is expected to have a greater life expectancy compared to a mechanical mouse. Optical mouse is designed with no moving parts, which means less wear and a lower chance of failure. The mechanical mouse, because of its design, has a life expectancy of 1 to 2 years only. Tolerance against dirt and dust Mechanical mouse uses a trackball that acquires Image from www.HowStuffWorks.com a lot of dirt and dust during operation. These requires mechanical mouse user to frequently The rollers inside the mouse are in contact with clean the mouse. Optical mouse has no rolling track ball. As shown in the picture below, the parts thus; dust or dirt cannot get inside the white rollers protrude and touch the ball. The mouse and affect the tracking sensor. Optical first roller detects the horizontal movements of mouse does not require cleaning except for the the mouse, while the other roller which is placed dust debris collected on its underside. 90 degrees of the first roller detects the vertical movements. When the ball is rolling, one or Power consumption both rollers rotate as well. 2 PC Technology 2 A mouse has an on-board processor that converts these electrical signals into its binary equivalent. The chip will then send the 1’s and 0’s combinations to the PC using the mouse cord. A sample mouse processor developed by Logitech is shown below. The rollers are connected to a shaft and the shafts spin the chopper wheel between the light transmitter and receiver. The chopper wheel (sometimes called “decoder disk”) has 36 holes around its edge that is used to alternately break and restore the light signal. It uses an infrared LED to transmit the light and an infrared sensor to receive it as shown below. Image from www.HowStuffWorks.com [How Mechanical Mouse Works, Pages 7-12 of 32] How Optical Mouse Works As discussed earlier, an optical mouse works like a tiny camera that produces thousands of snap shots every second. Built-in CMOS (Complementary Metal Oxide Semiconductor) sensors transmit these images to the DSP (Digital Signal Processor) for processing. The DSP will analyze the image patterns and recognize the changes from one image to Image from www.HowStuffWorks.com another. Based on these changes, the DSP will determine how far and which direction does the mouse travels and sends the coordinates to the Shown below is a close-up look of an infrared PC. The computer will move the mouse pointer LED on one side of the chopper wheel and an to the location (coordinates) sent by DSP on the infrared sensor on the other side. As the screen. This process is done continuously every chopper rotates, it breaks and restores the light second so it appears that the mouse pointer is signal alternately. These light pulses are moving smoothly. converted into electrical pulses which are directly related to the movement of the mouse pointer on the screen. There are also 2 pairs of infrared transmitter and sensor on each side of the wheel; theseare used to determine the direction of wheel rotation. Image from www.HowStuffWorks.com Image from www.HowStuffWorks.com Shown above is a sample of an optical mouse underside. It has a LED and a photodiode. Wireless Mouse Most wireless mouse uses the RF (Radio Frequency) technology to transmit data to the computer. A wireless mouse has a transmitter (connected to the mouse) and a receiver 3 (connected to the PC). RF mice use different A wireless receiver can be a card or any frequencies to avoid communication conflict. It external plug-in device that utilizes computer has a transmission range of 6 feet to 33 feet and ports (commonly used is USB). operates at 27 MHz RF is better than infrared Bluetooth Mouse (IR) technology because IR can only accommodate short-range transmission and Bluetooth is also known as PAN (Personal Area requires the line of sight between the transmitter Network) and is one of the most common RF and receiver. Shown below is a sample wireless technology used in wireless mouse. A Bluetooth mouse with a docking station. This docking mouse has a range of 33 feet and operates at a station is where a mouse is placed when not in range of 2.4 GHz. It can accommodate multiple use. The docking station also serves as charger Bluetooth signal coming from other devices at for the wireless mouse battery. one time, but uses the techniques called frequency hopping to avoid signals interference. How Wireless Mouse Works The transmitter of a wireless mouse resides Shown above is a Bluetooth mouse developed inside the mouse housing. It converts hand by Targus Technologies and it has the Bluetooth motion into radio signal that is sent to the PC.