Patent Application
20060066227
This disclosure relates generally to a dual display arrangement and an electronic device using this dual display arrangement.
Certain portable electronic devices, such as some cellular telephones, have more than one display. Often, these displays are in a back-to-back arrangement with a first display facing one direction and a second display facing an opposite direction. Other portable electronic devices, such as cordless telephones, laptop computers, personal digital assistants (PDAs), cameras, and remote controllers, could benefit from more than one display. Generally speaking, however, more displays lead to increased power consumption, increased manufacturing costs, increased device size, and more complex display circuitry.
There is an opportunity to make a dual display electronic device more efficient by re-using elements from one display in the other display. The various aspects, features and advantages of the disclosure will become more fully apparent to those having ordinary skill in the art upon careful consideration of the following Drawings and accompanying Detailed Description.
An electronic device with a dual display arrangement has a housing with a first view port and a second view port. The electronic device also has a display module with a first display viewable through the first view port, a second display viewable through the second view port, and a light guide configured to direct light emitted by the second display for use as backlighting for the first display. The dual display arrangement allows an organic electroluminescent display (OLED) to serve as a backlight for a liquid crystal display (LCD) as well as operate as a viewable display. This arrangement eliminates the need for separate light emitting diodes (LEDs) to backlight the LCD. Instead, a light guide channels light emitted from the rear of the OLED to backlight the LCD. If the OLED and the LCD are arranged back-to-back, a straightforward light guide can be used to create a thin dual display for an electronic device.
The upper portion of the electronic device 100 has a housing 110 for holding the dual display module 150. This first embodiment shows a back-to-back dual display module, which is useful in the foldable mobile terminal or cellular telephone environment being described. The housing 110 has a first side 113 with a first view port 115 for viewing a first display 152.
Because this first embodiment shows a foldable mobile terminal or cellular telephone, the second view port 119 is visible and the first view port 115 is covered when the electronic device 100 is in the closed position shown in
A user interface of the electronic device 100 includes, in addition to the dual displays 152, 155, a loudspeaker 190, a microphone 180, and a keypad 170. The electronic device 100 also has other elements necessary to a mobile terminal or cellular telephone, which are not presented here for the sake of clarity. Such other elements include an antenna, a radio frequency transmitter, a radio frequency receiver, baseband circuitry, a microprocessor, a controller, memory, and a battery.
Although this first embodiment shows back-to-back displays, the displays do not need to be positioned back-to-back (i.e., at 180 degrees relative to each other with at least one display fully overlapped by the other display). Alternately, the dual displays can implemented in other configurations such as facing opposite directions and positioned side-by-side (i.e., at 180 degrees relative to each other with no overlap of the displays), facing opposite directions and partially overlapping (i.e., at 180 degrees relative to each other with neither display being fully overlapped by the other display), facing the same direction and positioned side-by-side, and facing yet other directions (e.g., at 90 degrees relative to each other), etc.
The first display 452 is designed to be a main display for a portable electronic device. Thus, the first embodiment uses a high-resolution color LCD as the first display 452. Of course, a low-resolution and/or monochromatic LCD can be implemented as the first display 452. The second display 455 is intended to be a secondary display and uses a smaller multi-color OLED. The second display 455 can show, for example, a calling line identity (CallerID), the current date and time, or indicate the owner of the electronic device. By using a multi-color OLED, the generation of colored light for backlighting the LCD can be controlled by an OLED display driver, or color filters can be used to change colored light from the OLED to white light for backlighting the LCD. Alternately, a monochromatic OLED can be used as the second display 455, and color filters can be used to provide multi-colored backlighting for the first display 452.
The first display 552 in this alternate embodiment is implemented as a liquid crystal display (LCD). The LCD can use TFT, CSTN, or other type of display technology. The LCD can be black-and-white or color.
The first front polarizer 531 and the first rear polarizer 538 are optional. The first front transparent substrate 533 and the first rear transparent substrate 537 are constructed from glass, plastic, or the like. The first front transparent electrode layer 534 and the first rear transparent electrode layer 536 are constructed from indium tin oxide (ITO), indium-doped zinc oxide (IZO), or the like. The liquid crystal layer can use twisted nematic, super-twisted nematic, cholesteric, or other types of liquid crystal materials.
The second display 555 in this alternate embodiment is implemented as an organic electroluminescent display (OLED). The OLED can be a monochromatic or multi-color OLED.
The second front polarizer 541 and the second rear polarizer 548 are optional. The second front transparent substrate 543 and the second rear transparent substrate 547 are constructed from glass, plastic, or the like. The front transparent electrode layer 544 (anode) and the rear transparent electrode layer 546 (cathode) are constructed from indium tin oxide (ITO), indium-doped zinc oxide (IZO), or the like. The electroluminescent layer can use small molecule or polymer construction.
Instead of using LEDs as light sources for a conventional backlight for the LCD, light emitted by the OLED is used for backlighting the LCD. A light guide 551 between the first display 552 and the second display 555 channels light from the rear of the OLED through an optical sheet or diffuser 553 to the rear of the LCD. A color filter layer 554, shown between the light guide 551 and the rear of the first display 552 in this embodiment, can also be included.
An opaque frame 512, such as a metal frame, helps hold together the display module 500, masks exposed portions of the larger first display 552 from the smaller second display 555, and provides stability and rigidity to the display module 500. A flexible circuit 520 provides control signals to a first display driver 523 to control the first display 552 and to a second display driver 526 to control the second display 555.
This embodiment uses two separate display drivers 523, 526 that can be independently controlled or controlled jointly. For example, the second display 555 might be considered a “main display” when the electronic device is in a closed position (such as the electronic device 100 shown in
Although the larger display (the first display 552) is shown as an LCD and the smaller display (the second display 555) is shown as an OLED in this alternate embodiment, the OLED display could be larger than the LCD display. Various factors, such as power consumption expectations, expectations for color quality (e.g., 256 colors, 1024 colors, or more), expectations for screen resolution, screen size demands, the specific application for a particular electronic device, and improvements in OLED and LCD technology, can affect the implementation of the dual display module. Note that if the OLED has a larger display area than the LCD, a partial display mode for the OLED can be used to conserve power or vary the backlight intensity. If the OLED has a smaller display area than the LCD, the OLED will be “on” whenever either display is in use.
Back-to-back display modules enable thinner, smaller, and/or less complex light guides to channel light from the OLED to the LCD to use as LCD backlighting. As discussed earlier, however, the display module need not be back-to-back and could instead be facing directions other than 180 degrees relative to each other. Additionally, the relative sizes of the first display and the second display can be varied, as well as the amount of overlap between the first display and the second display.
Thus, the dual display arrangement provides two displays and an alternative to traditional backlighting. By using light generated by an OLED to backlight an LCD, a conventional LED-based backlight can be eliminated. Given the larger light-generating area of an OLED relative to conventional LED-based backlighting, a thinner light guide can channel light from the OLED to the rear of the LCD. These changes can result in a thinner dual display module.
While this disclosure includes what are considered presently to be the preferred embodiments and best modes of the invention described in a manner that establishes possession thereof by the inventors and that enables those of ordinary skill in the art to make and use the invention, it will be understood and appreciated that there are many equivalents to the preferred embodiments disclosed herein and that modifications and variations may be made without departing from the scope and spirit of the invention, which are to be limited not by the preferred embodiments but by the appended claims, including any amendments made during the pendency of this application and all equivalents of those claims as issued.
It is further understood that the use of relational terms such as first and second, top and bottom, and the like, if any, are used solely to distinguish one from another entity, item, or action without necessarily requiring or implying any actual such relationship or order between such entities, items or actions.
