Patent Application
20070152955
This invention relates generally to a reduced power consumption display
It is common to provide electronic computing devices with display devices to facilitate the visualization of graphic elements. With reference to
Typically, the formation of an image upon display panel 21 requires that each pixel forming the display area 13 of the display panel 21 be maintained at a common voltage, VCOM. Common video source signals range from approximately 0V to 10V and provide intensity information that appears across each pixel as a voltage. One side of each pixel is commonly connected to the backplane of the display panel 21 at a node common to all pixels. The voltage at this node is referred to as VCOM.
In some implementations, VCOM is maintained at ground, or 0V. Such a set-up, while functional, reduces display panel 21 lifetime. When VCOM is at ground, the voltage across individual pixels can, using the exemplary parameters noted above, vary from 0V to 10V. Under such a scenario, the average voltage across any single pixel over time is approximately 5V forming a near constant DC voltage across each pixel. This DC voltage can cause charge storage, or memory. Over time, this charge storage tends to degrade pixels by electroplating ion impurities onto one of the electrodes forming a pixel. As a result, a residual, or sticking image, is permanently burned into the display.
Because the construction of LCD panels is symmetrical, either a positive or a negative voltage can be used to align the crystals. This aspect of LCD display panels can be used to increase the longevity of LCD displays. Specifically, the VCOM can be moved to a value approximating the midpoint of the video signal. This causes the video signal voltage to swing both above and below the VCOM resulting in a net zero voltage effect on each pixel. This net zero effect serves to largely eliminate the aging and retention issues discussed above.
Typical values for VCOM range from 0V to approximately 5V. Depending on the overall intensity of an image displayed on the display panel, the average voltage across the pixels forming the display will vary from frame to frame. It is therefore preferable to make adjustments to the applied VCOM periodically, such as between sequential frames, so that VCOM more closely approximates an instantaneous average voltage across all of the pixels.
Maintaining the entire display area 13 at VCOM, even for an abbreviated period of time, requires energy. In many mobile devices, such as mobile telephones, the repeated provision of the VCOM to the display area 13 results in diminished battery life.
Often times, it is only required that a portion of the display area 13 be updated with an image. For example, partial display area 15 forms a generally vertical portion of display area 13. Areas such as partial display area 15 are often utilized to display specialized indicia and data such as battery and signal strength, time of day, network status, operator name, etc. In such instances, updating only the indicia or the data, each contained entirely within partial display area 15, requires providing VCOM to the entire display area 13.
What is needed is an apparatus to facilitate the alteration of a portion of the display area 13, such as partial display area 15, that does not require the provision of an unnecessary voltage to the display area 13.
In accordance with an exemplary embodiment of the invention, a display device includes a first display panel coupled to a first common voltage, and at least one additional display panel coupled to at least one additional common voltage, wherein the first display panel and the at least one additional display panel are coupled to form a single expanse and the first common voltage and the at least one additional common voltage are independently controllable.
In an alternative exemplary embodiment of the invention, a display module includes a display device formed of a first display panel coupled to a first common backplane, and a second display panel coupled to a second common backplane, wherein the first display panel and the second display panel are coupled to form a single expanse, a source driver having an input coupled to a display data source and an output coupled to the display device, and a common driver coupled to the source driver and to the first and second common backplane, wherein the common driver differentially controls a first common voltage provided to the first common backplane and a second common voltage provided to the second common backplane.
In an alternative exemplary embodiment of the invention, a method of controlling a display device includes providing a display device including a first display panel coupled to a first common backplane, and at least one additional display panel coupled to at least one additional common backplane, wherein the first display panel and the at least one additional display panel are coupled to form a single expanse, displaying display data on at least one of the first display panel and the at least one additional display panel, and independently providing at least one common voltage to each of the first common backplane and the at least one additional common backplane on which there is displayed display data.
In an alternative exemplary embodiment of the invention, a portable electronic device includes a display device comprising a first display panel coupled to a first common voltage, and at least one additional display panel coupled to at least one additional common voltage, wherein the first display panel and the at least one additional display panel are coupled to form a single expanse, and a processor coupled to the display device for controlling operation of the display device.
In an alternative exemplary embodiment of the invention, a program of machine-readable instructions is tangibly embodied on an information bearing medium and executable by a digital data processor performs actions directed toward providing a plurality of common voltages to a display device, the actions including receiving display data to be displayed on a display device comprising a first display panel coupled to a first common backplane and at least one additional display panel coupled to at least one additional common backplane, computing a first common voltage and at least one additional common voltage, and providing the first common voltage to the first common backplane and the at least one additional common voltage to the at least one additional common backplane.
In an alternative exemplary embodiment of the invention, an apparatus includes a means for receiving display data to be displayed on a display device comprising a first display panel coupled to a first common backplane and at least one additional display panel coupled to at least one additional common backplane, a means for computing a first common voltage and at least one additional common voltage, and a means for providing the first common voltage to the first common backplane and the at least one additional common voltage to the at least one additional common backplane.
The foregoing and other aspects of these teachings are made more evident in the following Detailed Description, when read in conjunction with the attached Drawing Figures, wherein:
With reference to
In the example illustrated, partial area 115 forms a portion of display area 113′. Partial area 115 can form any portion of display area 113′ up to, and including, all of display area 113′. Note that each display panel 121, 121′ is coupled to a separate common voltage, VCOM1, VCOM2, respectively. More specifically, each display panel is associated with a separate and individual common backplane to which is applied an individual VCOM as described more fully below. As a result, VCOM1 can be utilized to power the functioning of display panel 121 independent of the energy or graphic requirements of display panel 121′. Conversely, VCOM2 can be utilized to power the functioning of display panel 121′ independent of the energy or graphic requirements of display panel 121. In practice, the VCOM used to power each display panel 121 can be of the same value.
As is described more fully below, while utilizing separate common voltages, VCOM1, VCOM2, both display panels 121, 121′ can be operated by the same display driver 117.
With reference to
As described, each display panel 121, 121′ is a logical division of the physical display device 23 upon which an image can be formed. The measurements of each display panel 121, 121′ correspond to the physical dimensions of each associated common backplane 123, 123′ respectively. As described more fully below with reference to
With reference to
When provided with an image to display, for example an N×M pixel image, the source driver 711 provides the voltages corresponding to the intensity of the first row of pixels across source bus lines 1-M. Gate driver 713 then applies a voltage to gate bus line 1. As a result of the gate driver 713 applying such a voltage, all of the pixels 719 across the first row of display panel 23 assume their appropriate intensities. Source driver 711 next provides the voltages corresponding to the intensity of the second row of pixels across source bus lines 1-M. Gate driver 713 then applies a voltage to gate bus line 2. This process repeats itself until all N rows of the image have been displayed. A timing controller in the source driver 711 controls the timing of when the voltages applied to source bus lines 717 and gate bus lines 715 are refreshed.
With continued reference to
As noted above, the common voltage, VCOM, is applied to each pixel 719 via a common backplane 123. Source driver 711 receives control and data signals, such as from display driver 117. As will be described more fully below, one or more display drivers 117 can send image information to source driver 711 for display upon display device 23.
With reference to
In operation, the display drivers 117, 117′ receive input data from the processor 111. An example of such input data is data indicative of a signal strength to be displayed and further indicative of a signal strength value of four. Display driver 117′ receives this input and proceeds to control the functioning of individual pixels so as to create graphical indicia 131″ formed of four vertical bars. In a similar manner, device driver 117′ can proceed to control the display of alternative indicia 131, 131′ displaying the presence of a voice message and a battery strength respectively. While illustrated with respect to the presentation of graphical indicia 131, 131′, 131″, the output of the display driver 117′ is not so limited. Rather the output of display driver 117′ can be utilized to control a subset or all of the pixels forming partial area 115.
With reference to
While illustrated with embodiments wherein discreet graphical indicia 131-131′″ are displayed within discreet partial areas 115-115″, the invention is not so limited. If required, a single image can span more than one display panel 121. Doing so, however, requires the provision of a common voltage VCOM to more than one display panel 121 and thus reduces the power savings evident when only a single display panel 121 is utilized to display an image or graphical indicia 131. By selectively activating less than all of the display panels 121, the processor 111, often acting via a display driver 117, is able to reduce the power required by the display device 23. When operating in such a selectively activated mode, the display device 23 is deemed to be operating in a “partial mode”.
With reference to
In general, the various embodiments of the mobile station 57 can include, but are not limited to, cellular telephones, portable electronic devices, personal digital assistants (PDAs), portable computers, image capture devices such as digital cameras, gaming devices, music storage and playback appliances, Internet appliances permitting Internet access and browsing, as well as portable units or terminals that incorporate combinations of such functions.
The embodiments of this invention involving the creation of an image or images upon the display device 23 may be implemented by computer software executable by a data processor of the mobile station 57, such as the processor 111, or by hardware, or by a combination of software and hardware.
The memory 53, 51 may be of any type suitable to the local technical environment and may be implemented using any suitable data storage technology, such as semiconductor-based memory devices, magnetic memory devices and systems, optical memory devices and systems, fixed memory and removable memory. The data processor 111 may be of any type suitable to the local technical environment, and may include one or more of general purpose computers, special purpose computers, microprocessors, digital signal processors (DSPS) and processors based on a multi-core processor architecture, as non-limiting examples.
In general, the various embodiments such as controlling the display panels 121, may be implemented in hardware or special purpose circuits, software, logic or any combination thereof. For example, some aspects may be implemented in hardware, while other aspects may be implemented in firmware or software which may be executed by a controller, microprocessor or other computing device, although the invention is not limited thereto. While various aspects of the invention may be illustrated and described as block diagrams, or using some other pictorial representation, it is well understood that these blocks, apparatus, systems, techniques or methods described herein may be implemented in, as non-limiting examples, hardware, software, firmware, special purpose circuits or logic, general purpose hardware or controller or other computing devices, or some combination thereof.
Certain embodiments of the inventions may be practiced in various components such as integrated circuit modules. The design of integrated circuits is by and large a highly automated process. Complex and powerful software tools are available for converting a logic level design into a semiconductor circuit design ready to be etched and formed on a semiconductor substrate.
Programs, such as those provided by Synopsys, Inc. of Mountain View, Calif. and Cadence Design, of San Jose, Calif. automatically route conductors and locate components on a semiconductor chip using well established rules of design as well as libraries of pre-stored design modules. Once the design for a semiconductor circuit has been completed, the resultant design, in a standardized electronic format (e.g., Opus, GDSII, or the like) may be transmitted to a semiconductor fabrication facility or “fab” for fabrication.
