Everything about Push-button totally explained
A
push-button (often simply "
button" or "
pushbutton") is a simple
switch mechanism for
controlling some aspect of a
machine or a
process. Buttons are typically made out of hard material, usually
plastic or
metal. 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, though even many un-biased buttons (due to their physical nature) require a
spring to return to their un-pushed
state.
Uses
In industrial and commercial
applications push buttons can be linked 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 that have not got
electrical circuits in the machine or process.
Pushbuttons are often
color-coded to associate them with their function so that the
operator won't push the wrong button in
error. Commonly used colors are
red for stopping the machine or process and
green for starting the machine or process.
Red pushbuttons can also have large heads (called
mushroom heads) to for easy operation and to facilitate the stopping of a machine. These pushbuttons are called
emergency stop buttons and are mandated by the electrical code in many jurisdictions for increased safety. This large mushroom shape can also be found in buttons for use with operators who need to where
gloves for their work and couldn't actuate a regular
flush-mounted push button.
As an aid for operators and
users in industrial or commercial applications, a
pilot light is commonly added to draw the attention of the user and to provide
feedback if the button is pushed. Typically this light is included into the center of the pushbutton and a
lens replaces the pushbutton hard center disk. The source of the energy to illuminate the light isn't 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.
In
popular culture, the phrase "
the button" (sometimes capitalized) refers to a (usually fictional) button that a military or government leader could press to launch
nuclear weapons.
History
Buttons as control devices were unknown until the early 20th Century, with the possible exception of valves on
wind instruments. Where small controls were needed- for example on camera shutters- they were usually styled after latches or triggers, early
teleprinters had keyboards similar to keyboard instruments with white and black keys.
The earliest examples of buttons as currently understood were probably mechanical
typewriter keys in the early 20th Century, followed by electromechanical devices such as teleprinters and
teletypes. These became more closely associated with electrical switching when used as a component of devices such as the
Enigma Machine, and became commonplace in around the 1960s.
Further Information
Get more info on 'Push-button'.
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