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The combination of high-power LEDs and supercapacitors will solve the key problem of high-quality LED flash in camera phones, with a combination of low current and small size.
Although some camera phones now have high-quality lenses, image processing software, and high-pixel image sensors, there is still a large area to be developed in order to take a perfect photo. Almost no camera phone can be well imaged at low brightness in hotels, bars or rooms.
The key factor in solving this problem is to use a flash to provide enough light during the photo session. One way to measure the intensity of light is to count the sum of the illumination of the source (in lux) during the flash time. A light source with a light intensity of 10-15 lux. seconds is enough to take high-resolution images.
Many camera phones have already used LED flash, but the purpose is not fully achieved because of insufficient light. Most mobile phones are equipped with 1-2 watt LEDs, which can only provide less than 4 lux. seconds of light intensity at a distance of one meter. When the distance is 2 meters, there is only less than 1 lux.
High-power LEDs are developing rapidly. However, in order to achieve maximum brightness, they need more than 400% of the drive current compared to the 800-1000 mA that cell phone batteries can now provide.
Xenon flash
As an alternative to LEDs, some of the latest camera phone cameras are Xenon flash lamps that have been specifically tailored to use capacitive drives. Xenon flash provides excellent brightness for a short exposure time and is ideal for shooting moving objects and illuminating distant targets.
However, xenon flash lamps require a large capacity capacitor and are therefore bulky. For example, on Sony Ericsson's K800 phone, Xenon flash and peripheral circuits occupy 3.8 cubic centimeters. At the same time, storing up to 330V, 1.5 joules of energy in the place close to the ear, there are certain safety issues. Not only that, the recharge of the capacitor between shots took a long time (Sony Ericsson takes 8 seconds), this flash has no other use.
However, Xenon flash is not the only option. Australia's CAP-XX technology enables camera phones to use different power LEDs with different appearances. The company specializes in making ultra-capacitor capacitors for users, and they see the opportunity to combine this capacitor with high-power LEDs. In the construction of the CAP-XX BriteFlash LED flash, the supercapacitor is used to provide the current to drive the LED (above 1A), and the mobile phone battery is only used to charge the capacitor between the flashes.
According to Pierre Mars, deputy general manager of CAP-XX, if a 0.5F capacitor releases 1V during the flash, it only needs 250mA for 2 seconds of charging to take the next photo. . This feature is more than the current specifications required for existing standard LED flashlights: Electronic Design Technology 