Push-button

A button or a button (Italian Tasto, Latin Clavis ) is a control element which is actuated by pressing and then returns to the starting position. For this purpose, a mechanical spring is usually used. Unlike the switch ( which remains in the respective position) you can not visually tell if it has been operated with the key. Only on the associated action that is detectable.

Keys are used individually, such as a doorbell button, in a group of mostly labeled keys, called a key board or unlabeled keyboard keyboard instruments or the keypad of a computer. Keys, which are operated with the feet, called pedals.

Non-electric keys

The oldest keys can be found probably due to keyboard instruments. In piano, a lever is set in motion, for example, by the key on a leather strap, hitting a hammer against the string. In the organ, a valve to the associated organ pipe is open.

In the typewriter a type of levers and linkages is struck against the ribbon through most of the keys. But there are also the shift that lifts the roller to reach the capital letters, and the Caps Lock key, which ensures that the shift does not return again.

For compressed air- powered equipment (eg explosion-proof rooms ) there are pneumatic buttons.

For special electrical safety requirements, there are water through a hose and a membrane acting on a foot switch contact pushbutton switch, which consist only of a rubber hollow body.

Electric keys

Electric keys are usually mechanically operated probes, in which contacts are moved when actuated. Depending on the application the contacts are closed when operating, so each brought into contact (normally open ) or open ( NC). If using a button a permanent state change can be effected, for example, a light on or off, a switch circuit is employed.

Industry buttons often have contact pairs of both kinds - they have a NO contact and one of them electrically isolated opener.

Using membrane keys instead of solid pieces of metal conductors on films. Often, the cover sheet is fitted with a diaphragm spring with step function. The spring is then operating at the same time also produces the electrical connection. The step function facilitates the defined actuation. Membrane keys are only suitable for switching small currents. They are used in membrane switches and mobile phones.

Silicone Rubber Keypads ( colloquially Leitgummitasten ) consist of a conductive contact pill, which presses on a comb-like interlocking structure of conductive surfaces ( for example on a circuit board ). They are used in computer keyboards, remote controls, mobile phones, and in some buttons for PCB mounting.

When the touch panel keys in response to pressure or proximity with the finger in the modification of electrical or non-electrical parameters is.

Types of sensor keys:

• Hall buttons in a permanent magnet is brought close to a working with the Hall Hall effect sensor and a sensor in the integrated electronic hysteresebehafteter threshold generated from defined switching flanks. These buttons or Hall-effect switches require auxiliary voltage.
• Capacitive buttons react to the object created by the proximity of the finger on a sensor electrode capacitance change or Interference. They have no moving parts and are therefore robust. Capacitive buttons require an auxiliary voltage.
• Piezo keys include a piezoelectric element which generates an electric voltage when pressure changes. This voltage is used to control an electronic switch. Piezo buttons do not require auxiliary power.
• Touchscreens are two-dimensional, freely programmable, transparent keypads front of a screen or computer monitor. They usually operate on the principle of capacitive buttons, the sensor electrodes orthogonal to each other incorporated wires.
• Touchpad work as well as touch screens and serve in notebooks as a substitute for a computer mouse.
• So-called "soft keys" can be a touch screen, which alternate functions can be assigned by software actual buttons or fields. Using a computer mouse operated virtual keys on a screen other hand, are often referred to as a button.

Keys for electronic musical instruments not only report the fact that the button was pressed, but in addition provide the information, how strong or fast as she was pressed. This is done for example, by measuring the time, which is measured at the depression of the button between the two rear -side triggering button. This allows the mechanical piano as to make the volume and duration of the intensity of the stop of the key -dependent. This property electronic keyboard instruments is called velocity.

A plurality of keys arranged in a certain way (layout ), which form a keyboard. The keys are labeled to send different characters or trigger commands. Known layouts are the typewriter keyboard and telephone keypad. Derived from the typewriter keyboards are the computer keyboards. Membrane Switches on machines often have a function specific design. Electronic keyboards convert the parallel data into serial data stream so that they can be transmitted over one or a few lines.

Emergency stop button force due to their robust construction, the safe separation of one or more circuits. Return on operation often not in their original position, but must be returned by a train or rotary motion or by a key.

So-called anti-vandal keys offer even with the use of tools high security against vandalism. They can be found, inter alia, in elevators or other public facilities.

Special keys

• Eject button - Press to eject a disc in computers and hi- fi systems
• Morse key - key for the precise generation of Morse signals
• Signal - button telephone button with special functions