Balanced arm lamps

Balanced arm lamps

A balanced-arm lamp is a lamp with an adjustable folding arm which is constructed so that the force due to gravity is always counteracted, regardless of the position of the arms of the lamp. Many lamp brands (such as the Anglepoise and Luxo L-1 as well as other devices, such as drawing boards, use this principle.

Configuration

These lamp arms invite comparison with a human arm: the lamp cap is the hand, and there are three joints (equivalent to the wrist, elbow and shoulder) which connect it to the body, in this case reprsented by the base. Just as with the human arm, the advantages of the three joints are that the arm can reach virtually any point in space within a hemisphere with a radius equal to the arm's length. The same mechanism can be employed in other devices with similar requirements, such as copy holders for typists and some computer display holders. This article uses the terminology "lamp cap", "forearm", "upper arm" and "base" for the four basic parts of these lamps.

For the physics and theory behind balanced-arm lamps, see Classical mechanics, linkage and torque. There are different methods to balance the lamp-cap of a balanced-arm lamp. Some lamps have two coil springs working in parallel on both sides of the pivoting arm. (A set of springs functions in the same way as a single spring.) Others are balanced with counterweights (a method frequently used in drawing-boards). Friction between parts of the lamp arm can also be used to maintain balance. There are a number of mechanical solutions (coupling, hydraulics and pneumatic arms) which have occasionally been used for balanced-arm lamps.

Lamps balanced with springs

There are many variations of construction with springs. Springs can be located on the mechanical equivalent of the forearm or the upper arm, or both, as well as nearer the base. Some lamps use tension springs, and others use compression springs. The image at the left shows (left to right) a compression spring at rest, then under load, followed by a tension spring at rest, and then under load. Springs have a limited lifting capacity and extension length.Some springs can resonate, producing low-level unwanted noise.


One Tension spring

Two Tension springs

Lamps balanced by pressure and friction

In popular culture

Two spring balanced desk lamps of this type feature as the main characters in the Pixar animated film Luxo Jr..

References

ee also

* Engineering science and mechanics
* Industrial design
* Light fixture
* Torsion spring
* Mechanical advantage
* Mechanical engineering technology
* Moment (physics)

External links

* [http://www.ocp.tudelft.nl/project2006/wb14/referenties.html Dutch students from the University Delft Netherlands] experimenting to balance a lamp. In Dutch but with a lot of images.

Patents history

Classifications IPC :F21V21/26

International patent category : B23B31/171
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB191104491 GB191104491] An Improved Device for Supporting or Suspending Electric Lamps and the like (1911)

* - 1921 harmonica arm -
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB206435] 1923 parallelogram & counter weight
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB254972] 1926 friction
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB285045] 1929 2 counter weight
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB481198] 1934 spring and counter weight

*FR757890 1934 CARWARDINE GEORGE

*FR784932 1935 CARWARDINE GEORGE
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB470502] 1937 friction
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB489547] 1938 2 parallelogram 2 springs
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB504791] 1939 2 pressure springs
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB536342] 19.. a-symmetric arm-lamp
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB589994] 1947 friction and a spring
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB618344] 1949
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB629364] 1949 spring in the arm
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB713378] 1954 friction arm

# US patent|3003737A11961 -- 1961
* [http://www.delphion.com/cgi-bin/viewpat.cmd/GB1249774A] 1971

* - 1991 -

*EP0518569 1992

*EP1274545 2003 mechanical coupling devices


Wikimedia Foundation. 2010.

Игры ⚽ Поможем написать реферат

Look at other dictionaries:

  • Counterweight — For the Outer Limits episode, see Counterweight (The Outer Limits). Simple Crane A counterweight is an equivalent counterbalancing weight that balances a load.[1] Contents …   Wikipedia

  • Mechanical advantage device — Beam balanced around a fulcrum A simple machine that exhibit mechanical advantage is called a mechanical advantage device e.g.: Lever: The beam shown is in static equilibrium around the fulcrum. This is due to the moment created by vector force A …   Wikipedia

  • Anglepoise lamp — designer George Carwardine.Carwardine was a motor car designer who applied his engineering skill to build a lamp which mimicked the joints of the human arm. The joints and spring tension allow the lamp to be placed in a wide range of positions… …   Wikipedia

  • Tolomeo desk lamp — The Tolomeo incandescent desk lamp is an icon of Italian modern design. It was designed by Michele De Lucchi and Giancarlo Fassina in 1986 for the Artemide company. In its original configuration, it consists of a heavy base, two straight polished …   Wikipedia

  • Tizio — is a desk lamp created by Richard Sapper for Artemide in 1972. It has been selected for the Compasso d Oro industrial design award in 1979. An item of it is part of the collections of the Metropolitan Museum of Art [ Richard Sapper: Tizio table… …   Wikipedia

  • Light fixture — This article is about architectural light fixtures. For stage lighting, see Stage lighting instrument. Many various light fixtures A light fixture, light fitting, or luminaire is an electrical device used to create artificial light and/or… …   Wikipedia

  • interior design — 1. the design and coordination of the decorative elements of the interior of a house, apartment, office, or other structural space, including color schemes, fittings, furnishings, and sometimes architectural features. 2. the art, business, or… …   Universalium

  • motion-picture technology — Introduction       the means for the production and showing of motion pictures. It includes not only the motion picture camera and projector but also such technologies as those involved in recording sound, in editing both picture and sound, in… …   Universalium

  • arts, East Asian — Introduction       music and visual and performing arts of China, Korea, and Japan. The literatures of these countries are covered in the articles Chinese literature, Korean literature, and Japanese literature.       Some studies of East Asia… …   Universalium

  • technology, history of — Introduction       the development over time of systematic techniques for making and doing things. The term technology, a combination of the Greek technē, “art, craft,” with logos, “word, speech,” meant in Greece a discourse on the arts, both… …   Universalium

Share the article and excerpts

Direct link
… Do a right-click on the link above
and select “Copy Link”