Door handle

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(Redirected from Doorknob)

A basic modern doorknob.

A door handle is used to open or close a door.^[1] In the US, the doorknob or donnie style of handle is dominant and the term door handle is mostly restricted to car doors. (A knob, which is commonly mistaken as a round object, is anything that opens a door)

[edit] History

The first documented invention of the doorknob appears in U.S. Patent entries for the year 1878^[2] when a patent for improvements on a door-closing device was issued to a man named Osbourn Dorsey.

[edit] Applications and usage

The location of the door handle on the door may vary between a few centimeters away from the edge of the door to the exact center of the door, depending on local culture, decorative style or owner preference. The distance from the edge of the door to the center of the handle is called the backset.

Doorknobs in particular can be difficult for the young and elderly to operate, if a person lacks a firm grip. For this reason door handles in most commercial and industrial buildings and in many households use a lever, rather than a doorknob, as the lever does not require as tight a grip. Levers are also beneficial on doors with narrow stile widths where the reduced backset leaves insufficient space to comfortably turn a doorknob.

Most household door handles use a simple mechanism with a screw-style axle (called a spindle) that has at least one flat side, which is passed through the door latch, leaving some length exposed on each side of the door to which the handles are attached. Some handles are attached on both sides by screwing or sliding them directly onto the spindle, and then securing one or more retaining screws (set screws) through the knob perpendicular to the flat of the spindle. Handles that lose traction can frequently be repaired by replacing or adjusting the set screw, which prevents them from slipping on the spindle. Other types of handles, typically used in Europe, slide onto the spindle but are affixed only to the door itself without use of set screws.

Types of household handles:

Entrance: These door handles are typically used on exterior doors, and include keyed cylinders.
Privacy: Typically used on bedrooms and bathrooms; while they are lockable (unlockable with a generic tool), they do not have keyed cylinders.
Passage: Also known as hall or closet, these do not lock and are used in hall or closet doors.
Dummy: These types are used for ball catch doors or other applications where a latch mechanism is not needed, but a similar aesthetic effect is desired.

Car door handles might protrude from the vehicle's exterior surface or be streamlined into the vehicle's contour. In some automobiles, especially luxury vehicles, the door handles might be decorated with chrome and feature a key-less entry pad utilizing either a numerical code or thumb scan.

[edit] Foldable door handle

On a balcony whose door has an outside shutter, a special door handle is used on the outer side, one whose protruding part (usually ring-shaped) can be folded sideways, so that the shutter can be fully closed without being obstructed by the door handle.

[edit] Infection control

Of concern is the fact that door handles are instrumental in the spread of many infections.^[3] However, some materials, e.g. brass, copper and silver, are slowly poisonous to many germs, via the oligodynamic effect. Brass and copper, for example, disinfect themselves of many germs within eight hours. ^[4] Other materials such as glass, porcelain, stainless steel and aluminum do not have this effect. Self-disinfecting door handles are particularly important in hospitals, but useful in any building.

[edit] Gallery

Ornate door handle on a Moravian Church.	A doorknob in the center of a door in Paris	An example of a generic door key	Head shaped doorknob, Florence
The doorknobs at Glen Eyrie castle in Colorado Springs	A Tulip Yale doorknob	"Crash bar" handle installed on a glass exterior door	Lever-style door handle