Headlamp (outdoor)
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A headlamp, headlight, or head torch (UK) is a light source affixed to the head typically for outdoor activities at night or in dark conditions such as
Description
Headlamps are usually powered by three or four AA or AAA batteries, or rechargeable batteries. Systems with heavier batteries (4xAA or more) are usually designed so that the light emitter is positioned near the front of the head, with the battery compartment at the rear of the head.[citation needed] The headlamp is strapped to the head or helmet with an elasticized strap.[1] Some headlamps have a separate battery pack connected by a cable, to be carried on a belt or in a pocket.[1]
Headlamps may be held in place by a single band around the head or (particularly heavier ones) have an additional band over the top of the head.[citation needed]
Incandescent bulbs were used in headlamps until the introduction of white
History
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Carbide lamps were developed around 1900, and continued to be used after the introduction of battery lamps, which initially had poor battery life. Battery-powered headlamps with incandescent bulbs were used until the advent of LED lamps with much higher efficiency and consequently longer battery life.
Thomas Edison developed electric cap lamps for miners in 1914; by 1915, certain cap lamps were approved by the United States Bureau of Mines for safe use where there may be inflammable gas as in coal mines.[citation needed] These included features such as spring-loaded contacts to automatically disconnect broken bulbs.[3] These lamps consisted of an incandescent lamp with a reflector, and a belt-mounted wet-cell storage battery[citation needed] sized to power the lamp for the entire working shift.[citation needed] After 12 hours a 1917-era miner's lamp produced less than one candlepower and about 2 to 5 total lumens.[3] This pattern became popular for similar lamps.[4] Head lamps approved for use in coal mines are designed not to allow an internal spark to ignite flammable gas surrounding the headlamp.[citation needed]
Functions
While a head torch has the function of fitting on a person's head, being capable of being switched on and off, and illumination in front, there are many variations for different purposes.[5] They include:
- Being waterproof
- Variable light level, and flashing
- Motion sensorto allow switching on and off by waving a hand with no need to operate a switch
- Optional red light mode to preserve night vision
- Both rechargeable and disposable batteries supported, to be able to provide light after the rechargeable battery is discharged
- Beam may be narrow (spot), broad (flood), or focussable
- Lamp angle may be adjusted between forward to downward
- Maximum brightness may range from adequate for close work (e.g., 50 lumens), to very bright
See also
References
- ^ ISBN 0811720527.
- ISBN 1426209894pp. 166-169
- ^ ISBN 978-0-87335-322-9.
- ^ "Mine Lighting". Retrieved 9 January 2012.
- ^ "Review of a head torch from the viewpoint of fell runners". Fell Running Guide. Retrieved 11 March 2023.