The Problem with Today's Light Source Designs for Thin Devices

LCD devices generally include a light source, as liquid crystal materials themselves do not emit light. A typical light source, also referred to as a backlight, may include light sources along one or more edges which emit light into light guide panels (LGPs) which guide the light across the display area. To increase the uniformity and brightness over the display area, a typical LCD device may also include brightness enhancement film (BEF) layers which reflect and enhance the light. However, such efforts to increase uniformity and/or brightness may also increase the thickness and complexity of the backlight and the LCD device. Furthermore, the different films and parts of an LCD having a LED backlight may be susceptible to contamination.

Apple's Solution

Apple's patent generally relates to a liquid crystal display (LCD) device having an organic light emitting diode (OLED) backlight. In one embodiment, an OLED backlight may include one or more OLED pixels disposed between two glass substrates. The OLED backlight may be optically bonded to the back of an LCD, which may prevent contamination between the LCD and the OLED backlight and increase the mechanical rigidity of the display device.

Further, the OLED backlight may also be electrically connected with light modulating portions of the LCD, such that information transmitted to selected pixels of the LCD active matrix may also be transmitted to areas of the OLED backlight electrically connected to the selected LCD pixels. For example, grayscale information transmitted to selected LCD pixels may also be received by corresponding areas of the OLED backlight.

One or More OLED Backlight Elements

In some embodiments, an OLED backlight may include one or more OLED elements bonded between two glass pieces. The OLED backlight may be optically bonded to the back of light modulating layers of the LCD, which may prevent and/or reduce possible contamination between layers of the LCD and the OLED backlight. The bonding of the OLED backlight in the LCD may also increase the mechanical rigidity of the LCD, which may enable the use of thinner glass substrates and possibly reduce the thickness of the overall device. Further, an OLED backlight may generally be thinner than a typical LED backlight, and may also provide improved light uniformity without the use of light guides or additional brightness enhancing films.

Apple states that using OLED backlighting may be coming to Apple's Cinema Display, MacBooks and iOS devices such as the iPhone and iPad. Apple's patent FIG. 4 depicts a tablet-style form factor such as the iPad. Eventually it would be available for the iMac.

Apple's patent FIG. 8 noted above is that of a cross-sectional view of the layers which may be present in an OLED backlight.

Apple's patent background mentions television in passing, though the shift to OLED TV's is in the making at this very moment. While some think that OLED's may take another three or four years to come to market, you may want to rethink that position. DuPont has a new technology and process for AMOLED that could mark a breakthrough for TVs. A press release was issued last week.

"AMOLED televisions clearly represent the future. They are preferred by consumers for their superior performance, they are more energy efficient and the process technology we're licensing allows them to be manufactured much more cost effectively," said David B. Miller, president, DuPont Electronics & Communications. "We look forward to helping make the promise of AMOLED television a commercial reality at a price point that is within reach for the mass consumer market."

It's already been licensed to a mysterious Asian AMOLED manufacturer. It may not relate to Apple just yet, but you never know.

For now however, the focus of the patent is definitely on a next generation iPad.

Apple's patent application was originally filed in Q2 2010 by inventor Nicolas Merz.

Notice: Patently Apple presents a detailed summary of patent applications with associated graphics for journalistic news purposes as each such patent application is revealed by the U.S. Patent & Trade Office. Readers are cautioned that the full text of any patent application should be read in its entirety for full and accurate details. Revelations found in patent applications shouldn't be interpreted as rumor or fast-tracked according to rumor timetables. Apple's patent applications have provided the Mac community with a clear heads-up on some of Apple's greatest product trends including the iPod, iPhone, iPad, iOS cameras, LED displays, iCloud services for iTunes and more. About Comments: Patently Apple reserves the right to post, dismiss or edit comments.

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