A push-button (also spelled pushbutton) or simply button is a simple

switch In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type of ...

mechanism to control some aspect of a

machine A machine is a physical system using Power (physics), power to apply Force, forces and control Motion, movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to na ...

or a

process A process is a series or set of activities that interact to produce a result; it may occur once-only or be recurrent or periodic. Things called a process include: Business and management *Business process, activities that produce a specific se ...

. Buttons are typically made out of hard material, usually

plastic Plastics are a wide range of synthetic or semi-synthetic materials that use polymers as a main ingredient. Their plasticity makes it possible for plastics to be moulded, extruded or pressed into solid objects of various shapes. This adaptab ...

metal A metal (from Greek μέταλλον ''métallon'', "mine, quarry, metal") is a material that, when freshly prepared, polished, or fractured, shows a lustrous appearance, and conducts electricity and heat relatively well. Metals are typicall ...

. The surface is usually flat or shaped to accommodate the human finger or hand, so as to be easily depressed or pushed. Buttons are most often biased switches, although many un-biased buttons (due to their physical nature) still require a

spring Spring(s) may refer to: Common uses * Spring (season) Spring, also known as springtime, is one of the four temperate seasons, succeeding winter and preceding summer. There are various technical definitions of spring, but local usage of ...

to return to their un-pushed state. Terms for the "pushing" of a button include pressing, depressing, mashing, slapping, hitting, and punching.

Uses

The "push-button" has been utilized in

calculators An electronic calculator is typically a portable electronic device used to perform calculations, ranging from basic arithmetic to complex mathematics. The first solid-state electronic calculator was created in the early 1960s. Pocket-size ...

push-button telephone The push-button telephone is a telephone that has buttons or keys for dialing a telephone number, in contrast to having a rotary dial as in earlier telephone instruments. Western Electric experimented as early as 1941 with methods of using mech ...

kitchen appliances A home appliance, also referred to as a domestic appliance, an electric appliance or a household appliance, is a machine which assists in household functions such as cooking, cleaning and food preservation. Appliances are divided into three ...

, and various other mechanical and electronic devices, home and commercial. In industrial and commercial applications, push buttons can be connected together by a mechanical linkage so that the act of pushing one button causes the other button to be released. In this way, a stop button can "force" a start button to be released. This method of linkage is used in simple manual operations in which the machine or process has no

electrical circuit An electrical network is an interconnection of electrical components (e.g., batteries, resistors, inductors, capacitors, switches, transistors) or a model of such an interconnection, consisting of electrical elements (e.g., voltage sources, ...

s for control. Red pushbuttons can also have large heads (called mushroom heads) for easy operation and to facilitate the stopping of a machine. These pushbuttons are called

emergency stop A kill switch, also known as an emergency stop (E-stop), emergency off (EMO) and as an emergency power off (EPO), is a safety mechanism used to shut off machinery in an emergency, when it cannot be shut down in the usual manner. Unlike a normal ...

buttons and for increased safety are mandated by the electrical code in many jurisdictions. This large mushroom shape can also be found in buttons for use with operators who need to wear gloves for their work and could not actuate a regular flush-mounted push button. Knopka 8 ugolnik

As an aid for operators and

user Ancient Egyptian roles * User (ancient Egyptian official), an ancient Egyptian nomarch (governor) of the Eighth Dynasty * Useramen, an ancient Egyptian vizier also called "User" Other uses * User (computing), a person (or software) using an ...

s in industrial or commercial applications, a pilot light is commonly added to draw the attention of the user and to provide

feedback Feedback occurs when outputs of a system are routed back as inputs as part of a chain of cause-and-effect that forms a circuit or loop. The system can then be said to ''feed back'' into itself. The notion of cause-and-effect has to be handled ...

if the button is pushed. Typically this light is included into the center of the pushbutton and a

lens A lens is a transmissive optical device which focuses or disperses a light beam by means of refraction. A simple lens consists of a single piece of transparent material, while a compound lens consists of several simple lenses (''elements''), ...

replaces the pushbutton hard center disk. The source of the energy to illuminate the light is not directly tied to the contacts on the back of the pushbutton but to the action the pushbutton controls. In this way a start button when pushed will cause the process or machine operation to be started and a secondary contact designed into the operation or process will close to turn on the pilot light and signify the action of pushing the button caused the resultant process or action to start. To avoid an operator from pushing the wrong button in

error An error (from the Latin ''error'', meaning "wandering") is an action which is inaccurate or incorrect. In some usages, an error is synonymous with a mistake. The etymology derives from the Latin term 'errare', meaning 'to stray'. In statistics ...

, pushbuttons are often

color-coded A color code is a system for displaying information by using different colors. The earliest examples of color codes in use are for long-distance communication by use of flags, as in semaphore communication. The United Kingdom adopted a color c ...

to associate them with their function. Commonly used colors are red for stopping the machine or process and green for starting the machine or process. In

popular culture Popular culture (also called mass culture or pop culture) is generally recognized by members of a society as a set of practices, beliefs, artistic output (also known as, popular art or mass art) and objects that are dominant or prevalent in a ...

, the phrase "the button" (sometimes capitalized) refers to a (usually fictional) button that a military or government leader could press to launch

nuclear weapon A nuclear weapon is an explosive device that derives its destructive force from nuclear reactions, either fission (fission bomb) or a combination of fission and fusion reactions ( thermonuclear bomb), producing a nuclear explosion. Both bom ...

Scram and scramble switches

Akin to

fire alarm A fire alarm system warns people when smoke, fire, carbon monoxide or other fire-related or general notification emergency, emergencies are detected. These alarms may be activated automatically from smoke detectors and heat detectors or may also ...

switches, some big red buttons, when deployed with suitable visual and audible warnings such as flashing lights and sirens for extreme exigent emergencies, are known as "scram switches" (from the slang term

scram A scram or SCRAM is an emergency shutdown of a nuclear reactor effected by immediately terminating the fission reaction. It is also the name that is given to the manually operated kill switch that initiates the shutdown. In commercial reactor ...

, "get out of here"). Generally, such buttons are connected to large scale functions, beyond a regular fire alarm, such as automated shutdown procedures, complete facility power cut, fire suppression like halon release, etc. A variant of this is the scramble switch which triggers an alarm to activate emergent personnel to proactively attend to and go to such disasters. An air raid siren at an air base initiates such action, where the fighter pilots are alerted and "

scrambled Scrambled eggs is a dish made from eggs (usually chicken eggs) stirred, whipped or beaten together while being gently heated, typically with salt, butter, oil and sometimes other ingredients. Preparation Only eggs are necessary to make scrambled ...

" to their planes to defend the base.

References

External links

Spring Return Button
by Sándor Kabai,

The Wolfram Demonstrations Project The Wolfram Demonstrations Project is an organized, open-source collection of small (or medium-size) interactive programs called Demonstrations, which are meant to visually and interactively represent ideas from a range of fields. It is hos ...

. {{Switches Human–machine interaction Switches

Uses

Scram and scramble switches

See also

References

Further reading

External links