Samuel Delesalle EP413 How Things Work Oct 12 2017 Computer Mouse Samuel Delesalle EP413 How Things Work Oct 12 2017

Introduction Brief History Different forms of mice and how they work Transducers in a computer mouse Hardware and Software required Retrieved from http://maronewellness.com/wp-content/uploads/2015/04/computer-mouse-with-real-mouse.jpg

A Short History 1926: Joystick invented 1952 First Trackball in use, used a 5 pin bowling ball 1968 First mouse, Engelbart mouse, used two wheels 1972 Mechanical (ball) mouse become popularized 1980 Optical mouse introduced to market 1998 Laser mice developed but not popularized till 2004 Retrieved from :https://en.wikipedia.org/wiki/Computer_mouse

Mechanical Mice 3-rollers with steel ball Each tracking rotor is attached to a 2-bit encoder Early mice sent these logic signals directly to the computer Later mice used internal IC Retrieved from https://www.quora.com

Optical Mice Use an LED and an array of imaging photodiodes Generally red or infrared LED Early versions required special “gridded” mousepads Thousands of pictures per second Use CMOS sensor Retrieved from: https://www.quora.com/How-does-an-optical-mouse-work

Photodiode Sense Electromagnetic radiation Use p-n junction semiconductor Photons excite electrons from valence band to conduction band This creates an electron hole pair When a minority charge carrier drifts to the depletion region it is swept across by the electric field resulting in a current Silicon has a bandgap of 1.1eV ~ 1128nm Silicon diodes operate from ~200nm -~1100nm Retrieved from: https://www.aptechnologies.co.uk/support/photodiodes/photodiode-theory-of-operation

CMOS Sensor Complementary-symmetry Metal–Oxide–Semiconductor Uses complementary n and p type MOSFETs An array of pixels each containing a photodiode Scans pixels in a top to bottom range Retrieved from: https://en.wikipedia.org/wiki/Active_pixel_sensor

Laser Mice Very similar to Optical mice Also use imaging CMOS sensor Use VCSEL, Vertical cavity surface emitting laser Laser wavelength is generally infrared Lasers penetrate surface providing a different range of mousepad materials

VCSEL, Vertical Cavity Surface Emitting Laser Semiconductor laser diode Perpendicular emission Produces coherent photons Quantum well holds electrons of similar energy N-type and P-type layers act as mirrors forming a waveguide Retrieved from: https://en.wikipedia.org/wiki/Vertical-cavity_surface-emitting_laser

Optical Mice Vs Laser Mice Laser mice have a higher intensity beam resulting in higher maximum sensitivity / DPI Laser mice see into surfaces and feel jittery at slow motions Optical mice 1% variation Laser mice 5% variation Laser mice work on almost any surface Optical mice function best on mousepads Retrieved from: https://www.quora.com/How-does-an-optical-mouse-work

Mouse Buttons Miniature snap action switch or micro switch 3-pin switch All or nothing response 2 conductive springs The flat spring is held in place by the curved spring When enough pressure is applied the flat spring starts to move This motion reduces the force applied by the curved spring resulting in an over the center motion referred to as a click Retrieved from: https://en.wikipedia.org/wiki/Miniature_snap-action_switch

Scroll Wheel First developed in 1985, first commercial model in 1995 Potentiometers or optical encoders Potentiometer must be able to do multiple loops Also use a micro switch on the bottom and possibly on the sides

Hardware in a Mouse Microprocessors New Logitech mouse uses a 32-bit ARM microcontroller Runs LED screen Use SROM, secure read only memory, newer mice are flash able for updates

Software Uses microprocessors to process data from optical sensor CMOS sensor produces analog output for each pixel These are converted into digital signals and the X and Y coordinate shifts are measured for each picture The X and Y shifts are converted into mouse motion based on DPI settings of the mouse Storing and controlling macros and key bindings Control lighting Power saving mode

Drivers Drivers are used for the mouse to interact with the OS Converts I/O from the mouse to signals the computer can understand Most Computer Mice will work without drivers but no extra features Interact with software on the mouse Enable special keys on the mouse Most Games in the past 15 years use direct input

Wire Vs Wireless Computer Mice In the past wired mice were faster but now wireless mice are catching up Wireless mice need internal battery Mice have a polling rate you can set between 125Hz and 1000Hz Higher polling rate has a higher power draw Monitors have a refresh rate of 120Hz and now up to 240Hz

Summary Many developments in the past 50 years Optical mice and laser mice both have their own benefits A computer mouse has many components each playing their own role Modern computer mice require complex hard and software for optimal operation Hardware is getting excessive

Questions?

References https://en.wikipedia.org/wiki/Main_Page Accessed October 9 2017 http://www.tech-faq.com/how-an-optical-mouse-works.html http://www.pcgamer.com/gaming-mouse-myths-busted/ https://www.bit-tech.net/news/tech/peripherals/steelseries-launches-mouse-with-32-bit-arm/1/ Accessed October 10 2017 http://www.pcgamer.com/how-gaming-mouse-firmware-works/ https://www.lifewire.com/whats-the-difference-between-optical-and-laser-mice-2640209 https://www.rp-photonics.com/quantum_wells.html Accessed October 11 2017 https://www.rp-photonics.com/laser_diodes.html