Team Extra Touch



Introduction:


Teaser: The future input system - multiple touch screen
 


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What is Multiple Touch Screen?

 

Multi-touch (or multitouch) is a human-computer interaction technique and the hardware devices that implement it, which allow users to compute without conventional input devices (e.g., mouse, keyboard). Multi-touch consists of a touch screen (screen, table, wall, etc.) or touchpad, as well as software that recognizes multiple simultaneous touch points, as opposed to the standard touchscreen (i.e. computer touchpad, ATM), which recognizes only one touch point. This effect is achieved through a variety of means, including but not limited to: heat, finger pressure, high capture rate cameras, infrared light, optic capture, and shadow capture.

A myriad of different applications for multi-touch interfaces both exist and are being proposed. Some uses are individualistic (e.g., iPhone, iPod touch, MacBook Pro, MacBook Air). However, multi-touch technology is mainly used to incorporate collaboration into the computing experience.    ---------   Wikipedia 

How do we achieve the goal?

We are using a capacitive touch screen (not of a resistive touch screen.)

Capacitive

A capacitive touch screen panel is coated with a material, typically indium tin oxide that conducts a continuous electrical current across the sensor. The sensor therefore exhibits a precisely controlled field of stored electrons in both the horizontal and vertical axes - it achieves capacitance. The human body is also an electrical device which has stored electrons and therefore also exhibits capacitance. When the sensor's 'normal' capacitance field (its reference state) is altered by another capacitance field, i.e., someone's finger, electronic circuits located at each corner of the panel measure the resultant 'distortion' in the sine wave characteristics of the reference field and send the information about the event to the controller for mathematical processing. Capacitive sensors can either be touched with a bare finger or with a conductive device being held by a bare hand. Capacitive touch screens are not affected by outside elements and have high clarity.

Resistive

A resistive touch screen panel is composed of several layers. The most important are two thin metallic electrically conductive and resistive layers separated by thin space. When some object touches this kind of touch panel, the layers are connected at certain point; the panel then electrically acts similar to two voltage dividers with connected outputs. This causes a change in the electrical current which is registered as a touch event and sent to the controller for processing. When measuring press force, it is useful to add resistor dependent on force in this model -- between the dividers.

A resistive touch panel output can consist of between four and eight wires. The positions of the conductive contacts in resistive layers differ depending on how many wires are used. When four wires are used, the contacts are placed on the left, right, top, and bottom sides. When five wires are used, the contacts are placed in the corners and on one plate.

4 wire resistive panels can estimate the area (and hence the pressure) of a touch based on calculations from the resistances.

Resistive touch screen panels are generally more affordable but offer only 75% clarity[citation needed] (premium films and glass finishes allow transmissivity to approach 85%[citation needed]) and the layer can be damaged by sharp objects. Resistive touch screen panels are not affected by outside elements such as dust or water and are the type most commonly used today.                        -- Wikipedia

So, this is the touch panel we are going to use. Have fun  :)

Touch panel