What do mobile device OEMs need from LED manufacturers? They want flash LEDs for cameras that are smaller, thinner and brighter. They also would like them to be easy to integrate, consume less power and provide high quality light. The ultimate goal is to enable users to take high-quality photos even in low-light conditions.
The good news is that LED manufacturers have been developing new designs to address some of these requirements. And these new developments will likely be welcomed by new product development designs, both designers and buyers, as demand continues to escalate for all types of mobile devices with integrated cameras.
Although many LED suppliers have focused on the development of LEDs for backlighting and the burgeoning lighting segment as energy efficiency becomes a big factor in next-generation designs, several LED vendors over the past year have noticed growing requirements for smaller, higher performance flash LEDs in mobile devices, particularly for smartphones.
Nearly every smartphone shipped has an embedded rear camera and one in three smartphones has a front-facing camera, according to a January 2013 ABI Research report. The number of tablets with two cameras is even greater. The market research firm projects that 2.7 billion cameras in mobile devices will ship in 2018. Smartphones still account for the majority of camera shipments, holding an 80 percent share.
Some of these designs include Osram Opto Semiconductor's specially-shaped lens that make the Oslux flash LEDs easier to integrate, while eliminating the need for additional covers or lenses for smartphones. Another innovation is Avago Technologies' use of a clear, non-diffused lens for its ASMT-Fx70 LEDs to provide high luminous intensity within a narrow radiation pattern, delivering high performance for precise auto-focus functionality in digital cameras.
In addition, both the Osram Oslux LEDs and Avago ASMT-Fx70 LEDs are available in small, compact packages that meet the designers need to cram higher functionality into ever-shrinking consumer electronics.
Osram's latest addition to its Oslux family specifically targets camera flash in smartphones. The company developed the "specially-shaped lens" that blends form with function, making it easier to integrate the LED into the design.
Osram said a challenge for designers of smartphones is "combining the actual camera with the lighting." And the new rectangular Oslux LED addresses this issue through its new design, delivering benefits to the buyer and designer. Consisting of two 1-square mm chips, the light-emitting area of the Oslux LED is flat, making it easier to integrate into the smartphone, and eliminating the need for additional covers or lenses, which reduces the bill of materials (BOM) costs. In addition, the LED can be installed vertically or horizontally, giving designers more flexibility.
In terms of brightness, the LED offers a brightness level of 150 lux at a distance of 1 meter, or approximately 3.3 feet. By using its UX:3 chip technology, the LED delivers very consistent illumination, allowing the LEDs to handle higher currents, and to get more light from the chip, while evenly distributing the light across the surface. As a result, it eliminates a hot spot in the center, which is often seen with conventional flashes, said Osram.
Here are the key Oslux stats:
- Luminous efficacy: 150 lux at 320 mA
- Package dimensions: (9.0 x 6.0 x 2.9) mm
- Radiation angle at 1 meter: (1,062 x 808) mm illumination target window
- Color temperature: 4500 K
For digital cameras, Avago Technologies developed a family of small auto-focus auxiliary flash LEDs. The company said the small package size combined with the high-performance auto-focus in the dark allows engineers to design thinner digital cameras. So how small is the LED? The ASMT-Fx70 LEDs measure 3.6- x 3.2- x 3.4-mm (LxWxH).
Avago said the new devices address the designer's challenge in terms of continually shrinking the digital camera, while providing greater functionality and capacity. The clear, non-diffused lens of the LEDs are said to provide high luminous intensity with a narrow radiation pattern, delivering consistent optical performance.
The ASMT-FJ70 (orange) devices use aluminum indium gallium phosphate (AlInGaP) material technology and offer a 12-degree viewing angle, while the ASMT-FG70 (green) devices use indium gallium nitride (InGaN) and provide a 14-degree viewing angle. Avago said "the narrow viewing angles deliver the long distance illumination and narrow beam pattern required for auto-focus auxiliary flash functionality."
Mobile device designers will continue to need smaller and thinner flash LEDs, combined with requirements for high quality lighting and multiple flashes. This is all part of the industry trend toward continued shrinking of mobile devices in overall size and thickness, while packing more features into smaller enclosures. It's likely that technological breakthroughs in materials and even manufacturability will be required to advance LED technology.
There is no doubt that suppliers will continue to develop technologies to meet these demands, enabling designers to simplify their designs, save space, and, in some cases, eliminate additional components such as covers and lenses to lower both BOM count and costs, always a plus for the buyers on new product development teams.