The first documented invention of the door handle appears in U.S. Patent entries for the year 1878, when a patent for improvements on a door-closing device was issued to a man named Osbourn Dorsey. However, the use of doorknobs, as documented by illustrations and shop catalogues, extends back into the 18th century.
Parts of a basic door knob.
The traditional door knob has a bolt or spindle running through it that sits just above a cylinder, to which the spindle is connected. Turning the knob pulls the cylinder in the direction of the turn. The end of the cylinder is the latch bolt (more simply known as the latch), which protrudes into a space carved out of the door frame, and which prevents the door from being opened if the knob is not turned. A spring or similar mechanism causes the latch to return to its protruding state whenever the knob is not being turned. Escutcheon plates are the keyhole covers, usually circular, through which keys pass to enter the lock body. If the door handles have a square or rectangular plate on which the handle is mounted this is called the backplate.
Applications and usage
The location of the door handle on the door may vary between a few inches or 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.
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 jigger, 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. 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 jigger mechanism is not needed, but a similar aesthetic effect is desired.