The US Patent and Trademark Office officially published a series of nineteen newly granted patents for Apple Inc. today. One of the patents that stood out from the crowd this morning relates to a high refresh rate LCD called FFS that Apple clearly states is suited for a TV. In fact, Apple's technology advances FFS so that it could work with large screen HDTVs, as previous versions of FSS couldn't accommodate such large displays. The technology is an off-shoot of IPS called S-IPS. It's a technology that provides superior performance and color gamut with high luminosity. IPS technology is currently being used in Apple's iMac – which stems from this patent.
Apple's Patent Background
Thin film transistor liquid crystal displays (TFT LCDs) are a well-known type of displays. One advanced type of TFTLCD is the fringe field switching TFT LCD, or FFS TFTLCD. Fringe field switching is considered to be a type of in-plane switching LCD; i.e., an LCD for which the electrodes performing the switching of pixels are in a single plane and formed on a single substrate on one side of the liquid crystals. (Other LCD technologies require that electrodes be placed in a "sandwich" configuration on two different substrates on both sides of the liquid crystals). An example of an FFS TFT LCD is described by Lee, Seung Hee et al., "Ultra-FFS TFT-LCD with Super Image Quality, Fast Response Time, and Strong Pressure-Resistant Characteristics," Journal of the Society for Information displays Oct. 2, 2002. The above publication is hereby incorporated by reference herein in its entirety for all purposes.
Furthermore, FFS LCDs usually require the use of a common layer. The common layer can be a single electrode that is used for switching all pixels. Thus, the common layer can be referred to as a common electrode. Each pixel may also include a pixel electrode and the switching of a pixel may be performed by varying a voltage between individual pixel electrodes and the common electrode. In some embodiments different common electrodes may be used for different rows of pixels.
The common electrode can be the same for all pixels (or, alternatively, all pixels in a particular row) and need not be individually switched for individual pixels. Each pixel electrode can be individually switched by the use of a transistor connected to a data and gate line. A plurality of gate and data lines can be provided in a lattice covering the display so that each pixel is connected to a respective gate and data line. This may allow the switching of individual pixel electrodes. Switching of an electrode indicates loading and/or removing charge to/from the electrode in order to change the voltage of an electrode.
Because of the need to use higher resistance transparent conductors to form the common electrode, the switching rate of the common electrode and, subsequently, the refresh rate of the display can be limited. Furthermore, to minimize the amount of current that has to flow across these higher resistance paths, FFS TFT LCDs are usually limited in size.
Apple's Invention Summary
Embodiments of Apple's granted patent and invention provide for a FFS TFT LCD with a high refresh rate without limiting the aperture of individual pixels. More specifically, embodiments of the invention provide for the use of common bus lines to reduce the effective resistance of the common electrode and to therefore allow for higher refresh rates of the display. Furthermore, the common bus lines can be positioned in such a manner so that they do not further reduce the aperture of the display. More specifically, the common bus lines can be positioned above or below existing elements of the display that are already opaque. Thus, adding the common bus lines need not reduce the aperture.
Embodiments of the present invention provide for the ability to reduce the effective resistance of the common electrode without reducing the aperture of the display. In other words, embodiments of the invention allow for relatively quick voltage changes at the common electrode without reducing the light transmitting portions of the display. Embodiments of the invention can produce FFS TFT LCDs that have high refresh rates, are relatively bright and feature relatively wide viewing angles. These benefits can also be extended to relatively large FFS TFT LCDs.
The Different Stages of the Manufacturing of a Substrate Assembly
Apple's patent FIG. 5 is a diagram showing embodiments of the present invention in various stages of manufacturing. Elements formed when manufacturing the substrate assembly are considered to be formed on the substrate and part of the substrate assembly even if they are not formed directly on the substrate but are formed on top of other elements that are formed on the substrate. There are, however, other layers that are part of the display but are not formed on the substrate or on another element that is formed on the substrate. These are instead separately produced and later combined with the substrate. These layers can include filters, polarizers, liquid crystals, other substrates, etc.
For a Future Apple TV
Embodiments of the present invention can be implemented in various types of devices. For example, with reference to FIG. 7, embodiments of the present invention can be implemented as flat screen television set 700 with display 701, a mobile telephone, a mobile device (such as a mobile music player), a laptop, a desktop or other types of devices. Embodiments of the invention may allow the above-referenced devices to provide a clear and bright display with a relatively high resolution, high refresh rate and a wide viewing angle.
Apple's Retina Display is the Future for TV
It's unknown at this time if the advanced S-IPS technology for FFS plays a role of any kind in the foundation for Apple's current Retina Display technology; the technology that's likely to end up in a (possible) future Apple HDTV.
Apple credits Shih Chang and John Zhong as the inventors of this patent which was originally filed in Q4 2008 and published today by the US Patent and Trademark Office.
Notice: Patently Apple presents only a brief summary of granted patents with associated graphics for journalistic news purposes as each Granted Patent is revealed by the U.S. Patent & Trademark Office. Readers are cautioned that the full text of any Granted Patent should be read in its entirety for full details. About Comments: Patently Apple reserves the right to post, dismiss or edit comments.
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