Mouse Touch Screen Haptic Technology Mouse Invented by

Mouse, Touch Screen, Haptic Technology

Mouse • Invented by Doug Engelbart • First commercial computer to come with a mouse: Apple Macintosh 1984.

Mouse guts

Detecting X and Y motion • As the ball rolls, two wheels (rollers) pick up the x- and y- components of the motion. • The roller moves a disk which has spokes that block light. A light and light sensor can detect the spokes as they go by and thus perceive motion.

Connecting a mouse Computer mice evolved from connecting through the Serial port, to a specialized PS/2 connector, to a USB connector.

Optical mouse • Effectively produces images of the surface the mouse in on. • Then analyzes the difference in those images from one time to the next in order to produce the motion.

Some old ideas • Since the mouse is producing consecutive images, two old ideas come into play: – Resolution – how many dots per inch (dpi) does the mouse in its image of the surface – Refresh rate – how often is the mouse taking images of the surface. Also related is how quickly it can calculate the image differences and convert them into motion.

Touch screens • First developed by E. A. Johnson at the Royal Radar Establishment, Malvern, UK. • First was “capacitive”. • Until recently could detect only a single touch with little to no information about the amount of pressure, etc.

A capacitor

A capacitor • A capacitor consists of two conducting plates separated by a non-conductor. • One plate gets a positive charge and the other a negative charge. • Among other things, the electrical properties of a capacitor is determined by the space between the plates.

Capacitive touch screen • In a capacitive touch screen there is one “plate” – for example, a thin layer of ITO (Indium Tin Oxide) chosen for its transparency. • The seconducting plate is the user’s finger or conductive stylus – its presence forms a capacitor. • Various techniques are used to determine where the touching occurs.

Resistive touch screen • A resistive touch screen has two layers and the pressure of the user’s touch moves the two layers closer changing the capacitor’s properties. • The user can wear gloves or use almost any kind of stylus.

SAW • Surface Acoustic Wave (SAW) sends out an ultra-sonic wave over the screen. – As we know the human hearing range goes up to 20 -some k. Hz (20, 000 Hz). Vibrational waves with higher frequencies are said to be ultrasonic • When the screen is touch part of the ultrasonic wave is absorbed. • The detection of where the wave is absorbed determines where the screen was touched.

Infrared/Optical Imaging • A crisscross of beams (usually in the infrared spectrum) is sent across the display surface and detected on the opposite side. • The user’s finger or stylus disrupts some of the beams and can thus be detected. • Like resistive, no properties of the touching object are assumed (beyond opaqueness to infrared).

Dispersive signal technology and acoustic pulse recognition • Dispersive signal technology: The stresses, strains etc. of the surface are detected at its edges and reverse engineered to determine where the screen was touched. • Acoustic pulse recognition: piezo-electrics (material where pressure and electric properties are coupled) are placed throughout. Pressures cause signals which can then determine location of touch

Haptic definition

Tactile Feedback to User • Touch screens and mice allow the user to put information into the system, but some systems provide tactile feedback, from letting your finger “know” it has clicked something to a more encompassing attempt to make a virtual experience feel real.

Grasping haptics • Early machines (not computers) allowed a user to interact with a control to grasp objects far away – For convenience – For added strength of machine – For protection from dangerous situation

Variations • Haptics: science of touch • Human haptics: specialized to human touch • Machine haptics: providing “touch” feedback that allows a user to control a real object via a machine (may include a computer) • Computer haptics: provides “touch” feedback that allows a user to experience a virtual object

First “computer haptics” • In 1993, the MIT Artificial Intelligence Laboratory made a device that gave a user haptic feedback – making it possible to touch a virtual object.

Type 1: Kinesthetic

From How. Stuff. Works • “Known as proprioceptors, these receptors carry signals to the brain, where they are processed by the somatosensory region of the cerebral cortex. The muscle spindle is one type of proprioceptor that provides information about changes in muscle length. The Golgi tendon organ is another type of proprioceptor that provides information about changes in muscle tension. The brain processes this kinesthetic information to provide a sense of the baseball's gross size and shape, as well as its position relative to the hand, arm and body. ”

Type 2: Tactile

Force Feedback

Haptic rendering • A way of calculating how a user is interacting with a virtual system and in turn what haptic feedback should be given to the user is known as “haptic rendering”.

References • http: //computer. howstuffworks. com/mouse. htm • http: //en. wikipedia. org/wiki/Touchscreen • http: //electronics. howstuffworks. com/gadget s/other-gadgets/haptic-technology. htm • http: //arstechnica. com/gadgets/2013/04/fro m-touch-displays-to-the-surface-a-briefhistory-of-touchscreen-technology/