A touch switch is a type of switch that only has to be touched by an object of greater capacitance to operate. It is used in many lamps and wall switches that have a metal exterior as well as on public computer terminals.
touchscreenincludes an array of touch switches on a display.
There are two types of switches called touch switches:
*Capacitance touch switch:A capacitance switch needs only one electrode to function. The electrode can be placed behind a non-conductive panel made of for example wood, glass or plastic.
*Resistance touch switch:A resistance switch needs two electrodes to be physically in contact with something electrically conductive (for example a finger) to operate.
Capacitance touch switch
A capacitance touch switch works using
body capacitance, a property of the human body that gives it great electrical characteristics. The lamp keeps charging and discharging its metal exterior to detect changes in capacitance. When a person touches it, it increases the capacitance and triggers the switch.
Capacitance switches are available commercially as
integrated circuits from among others:
Analog Devices: Model "AD7147" (12 channel).
Cypress Semiconductor CapSense: The "CY8C21434" can be configured as an 8-channel capacitance sensor, as used in the Apple iPod
Quantum Research Group, a division of Atmel: Model "QT 113".
Omron: Model "B6TS04LT" (4 channel) and "B6TS08LT" (8 channel).
Freescale: Model MPR083 and MPR084 can be configured as an 8-touch-pad sensor [ [http://www.freescale.com/webapp/sps/site/taxonomy.jsp?nodeId=0112698268 "Freescale proximity capacitive touch sensing technology"] ] .
AD Semiconductor: Model "TSM12" (12 channel) Door Lock SHS-5200.
These devices can also be used as a short-range
Resistance touch switch
A resistance touch switch works by lowering the resistance between two pieces of metal. It is thus much simpler in construction compared to the capacitance switch. Placing one or two fingers across the plates achieves a turn on or closed state. Removing the finger(s) from the metal pieces turns the device off.
One implementation of a resistance touch switch would be two darlington-paired transistors where the base of the first transistor is connected to one of the electrodes.
Also, an N-Channel, enhancement-mode, metal oxide field effect transistor can be used. Its gate can be connected to one of the electrodes and the other electrode through a resistance to a positive voltage.
* [http://home.howstuffworks.com/question42.htm HowStuffWorks.com answer to question: How do touch-sensitive lamps work?]
* [http://www.newelectronics.co.uk/article/7628/That-special-touch.aspx New Electronics: That Special Touch]
* [http://www.discovercircuits.com/DJ-Circuits/5vmom1.htm Capacitance touch switch]
* [http://www.aaroncake.net/circuits/touch.asp Resistance touch switch]
* [http://www.analog.com/library/analogDialogue/archives/42-05/AD7147_captouch.html AC Shield Enhances Remote Capacitive Sensing]
* [http://www.analog.com/library/analogDialogue/archives/41-12/capacitance_sensor.html Providing an Edge in Capacitive Sensor Applications]
* [http://www.analog.com/en/prod/0,2877,AD7147,00.html AD7147 CapTouch™ Programmable Controller for Single-Electrode Capacitance Sensors]
* [http://www.analog.com/en/content/0,2886,760%255F788%255F66102,00.html Capacitance-to-Digital Converter (CDC) Technology]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Membrane (touch) switch — Мембранный переключатель … Краткий толковый словарь по полиграфии
Switch — For other uses, see Switch (disambiguation). Electrical switches. Top, left to right: circuit breaker, mercury switch, wafer switch, DIP switch, surface mount switch, reed switch. Bottom, left to right: wall switch (U.S. style), miniature toggle… … Wikipedia
Touch-sensitive lamp — A touch sensitive lamp is one that is activated by human touch rather than a flip, pushbutton, or other mechanical switch. These lamps are popular as desk and nightstand lamps. They act on the principle of body capacitance.ee also*Touch… … Wikipedia
Touch Too Much — «Touch Too Much» Сингл AC/DC из альбома High … Википедия
Touch (Unix) — touch is a standard Unix program used to change a file s access and modification timestamps. It is also used to create a new empty file. History A touch utility appeared in Version 7 AT T UNIX. The version of touch bundled in GNU coreutils was… … Wikipedia
Touch the Dead — Developer(s) Dream On Studio Publisher(s) Eidos Interactive … Wikipedia
Switch (DJ) — Switch (a.k.a. Dave Taylor, A. Brucker, Solid Groove) is a UK based DJ, sound engineer and record producer. A leading figure of the fidget house genre, Switch runs his own music label Dubsided. He further produces with fellow DJ/Producer Sinden,… … Wikipedia
Touch Too Much — Single par AC/DC extrait de l’album Highway to Hell Face B Live Wire (live) Shot Down in Flames (live) Sortie 1979 (album) 1980 (single) Enregistrement 1979 … Wikipédia en Français
Touch football (rugby league) — Touchis a field game also known as Touch Football (particularly in Australia), Six Down (in South Africa) and Touch Rugby. In games of Touch, which originated from the sport of rugby league, touching an opposing player replaces a tackle, reducing … Wikipedia
Touch user interface — A Touch User Interface (TUI) is a computer pointing technology based upon the sense of touch (haptics). Whereas a graphical user interface (GUI) relies upon the sense of sight, the TUI enables not only the sense of touch to innervate and activate … Wikipedia