Patent Application
20060268197
This invention relates generally to the field of visual displays for electronic devices and the like.
Many cellular radio telephones have color displays that use a transflective color liquid crystal display (LCD). The operation of an LCD is a compromise between power consumption and optical performance.
Currently, the best optical performance is achieved by a field sequential transmissive display that has an always-on backlight. This type of display has a wide color gamut (wider than the typical display of a portable or laptop computer display) and high resolution (nine times the resolution of a typical portable computer display). However, the power consumption of this type of display is approximately 80 times that of a reflective display. This type of display cannot be used continuously on a cellular telephone.
The best reflective display, in terms of brightness, is the monochrome holographic display. However, such displays only provide monochrome operation.
The novel features believed characteristic of the invention are set forth in the appended claims. The invention itself, however, and further objects and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying drawing(s), wherein:
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one or more specific embodiments, with the understanding that the present disclosure is to be considered as exemplary of the principles of the invention and not intended to limit the invention to the specific embodiments shown and described. In the description below, like reference numerals are used to describe the same, similar or corresponding parts in the several views of the drawings.
In one embodiment of the invention, the backlight 110 is a field sequential backlight comprising red, green and blue (RGB) light emitting diodes (LED's). In operation, the RGB LED's may be turned on sequentially to provide a white light 118 that is synchronized with the liquid crystal cell 104. In operation, the light 118 is passed or blocked by the liquid crystal cell 104.
The hologram 108 is attached to the second polarizer 106 of the LCD cell 100. In operation, the hologram 108 reflects incident ambient light 120. The viewing cone 122 of the hologram is constrained to be narrow and is aligned in a preset direction.
In a further embodiment, a photo-sensor is incorporated into the display to provide for automatic adjustment of the backlight to maintain a desired color gamut.
The display may be operated in ‘color mode’ or in a ‘monochrome mode’. In the color mode of operation, the backlight is ‘on’. In this mode, the light from the backlight passes through the hologram and emerges from the display unaffected by the hologram. In the monochrome mode of operation, the backlight is ‘off’. In this mode, the hologram reflects a portion of the ambient light. There are no color filters in the liquid crystal cell or the polarizers, so the display is as bright as conventional holographic monochrome displays. Further, as the hologram is close to the liquid crystal cell, a high monochrome resolution can be achieved.
A combination color and monochrome display comprises multiple display cells arranged in an array pattern. Each cell provides a pixel element for the display. A combination color and monochrome display may be used in a variety of applications. In particular, a combination color and monochrome display may used in a user interface for a portable electronic device, such as a cellular phone, personal digital assistant, digital audio/video player, digital image viewer, gaming device or digital camera. Such devices often have both text and graphic modes. For example, a digital media player may show lists of songs in a text mode and show digital photographs in a graphic mode. The display of the present invention may be operated in the color mode to display high gamut color images and then switched to a high-brightness monochrome mode to display text for songs lists etc. In another example, a cellular telephone may display a vivid color images when initially turned on and then fade into a high brightness monochrome color. The monochrome mode of operation is suitable for many telephone operations. The display may also be used for non-portable electronic devices.
The display will consume less power when in operated in the monochrome mode compared with the color mode. For electronic devices where a monochrome mode is suitable for a substantial period of the operating time, the use of a combination color and monochrome display will result in significantly less power consumption. This, in turn, will lead to a longer battery life.
While the invention has been described in conjunction with specific embodiments, it is evident that many alternatives, modifications, permutations and variations will become apparent to those of ordinary skill in the art in light of the foregoing description. Accordingly, it is intended that the present invention embrace all such alternatives, modifications and variations as fall within the scope of the appended claims.
