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The combination of power LEDs and supercapacitors could provide the crucial breakthrough that will enable high quality LED flash in camera phones, with low current draw and small form factors. ![]()
Although some of today's camera phones have good quality lenses, image-processing software and high numbers of pixels in the image sensor, there is one big area of ​​development required to complete the picture. Few camera phones are able to take photos at the low light Levels that users experience in restaurants, bars or inside their friends' homes.
The key to taking good pictures in these environments is to tasty enough light energy is derived by summing the illuminance of the light source (measured in lux) over the duration of the Flash exposure time. A light energy of 10-15 lux.sec is thought to be ideal for high-resolution pictures at low light levels.
Many camera phones already use LEDs to provide some flash functionality, but these have not prove equal to the task as they do not arranged enough light energy illuminate their subjects. Most of todays phones with LED flash drive the LEDs at 1-2W and Provide less than 4 lux.sec of light energy at a distance of 1m from the phone to the subject, and less than 1 lux.sec at 2m.
Higher power LEDs would seem like the next obvious development. However, to achieve full light intensity, these require up to 400% more current than the 800-1000mA that a phone battery can usually provide for LED flash.
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This article was published in the February 2007 issue of LEDs Magazine.
To read the rest of this article, please visit our Magazine page, where you can download FREE electronic PDF versions of all issues of LEDs Magazine.
You can also request a print copy of LEDs Magazine (available by paid subscription). About the Author Sian Harris is a science and technology journalist and editor based in the UK.![]()
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The key to taking good pictures in these environments is to tasty enough light energy is derived by summing the illuminance of the light source (measured in lux) over the duration of the Flash exposure time. A light energy of 10-15 lux.sec is thought to be ideal for high-resolution pictures at low light levels.
Many camera phones already use LEDs to provide some flash functionality, but these have not prove equal to the task as they do not arranged enough light energy illuminate their subjects. Most of todays phones with LED flash drive the LEDs at 1-2W and Provide less than 4 lux.sec of light energy at a distance of 1m from the phone to the subject, and less than 1 lux.sec at 2m.
Higher power LEDs would seem like the next obvious development. However, to achieve full light intensity, these require up to 400% more current than the 800-1000mA that a phone battery can usually provide for LED flash.
+++++++
This article was published in the February 2007 issue of LEDs Magazine.
To read the rest of this article, please visit our Magazine page, where you can download FREE electronic PDF versions of all issues of LEDs Magazine.
You can also request a print copy of LEDs Magazine (available by paid subscription). About the Author Sian Harris is a science and technology journalist and editor based in the UK.
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