WO1998032116A1 - Power consumption control for a visual screen display by determining an order of pixel energization - Google Patents
Power consumption control for a visual screen display by determining an order of pixel energization Download PDFInfo
- Publication number
- WO1998032116A1 WO1998032116A1 PCT/US1998/000267 US9800267W WO9832116A1 WO 1998032116 A1 WO1998032116 A1 WO 1998032116A1 US 9800267 W US9800267 W US 9800267W WO 9832116 A1 WO9832116 A1 WO 9832116A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- pixels
- energization
- energized
- voltage
- screen
- Prior art date
Links
Classifications
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G3/00—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes
- G09G3/20—Control arrangements or circuits, of interest only in connection with visual indicators other than cathode-ray tubes for presentation of an assembly of a number of characters, e.g. a page, by composing the assembly by combination of individual elements arranged in a matrix no fixed position being assigned to or needed to be assigned to the individual characters or partial characters
- G09G3/2007—Display of intermediate tones
- G09G3/2018—Display of intermediate tones by time modulation using two or more time intervals
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0202—Addressing of scan or signal lines
- G09G2310/0213—Addressing of scan or signal lines controlling the sequence of the scanning lines with respect to the patterns to be displayed, e.g. to save power
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2310/00—Command of the display device
- G09G2310/02—Addressing, scanning or driving the display screen or processing steps related thereto
- G09G2310/0243—Details of the generation of driving signals
- G09G2310/0254—Control of polarity reversal in general, other than for liquid crystal displays
-
- G—PHYSICS
- G09—EDUCATION; CRYPTOGRAPHY; DISPLAY; ADVERTISING; SEALS
- G09G—ARRANGEMENTS OR CIRCUITS FOR CONTROL OF INDICATING DEVICES USING STATIC MEANS TO PRESENT VARIABLE INFORMATION
- G09G2330/00—Aspects of power supply; Aspects of display protection and defect management
- G09G2330/02—Details of power systems and of start or stop of display operation
- G09G2330/021—Power management, e.g. power saving
Definitions
- This invention generally relates to controlling a visual screen display to reduce the amount of power consumed when displaying an image. More particularly, this invention relates to a method of selectively energizing screen pixels to realize a desired screen brightness while saving power and reducing variations in the amount of energy used to power the display screen.
- a variety of visual screen displays are useful for displaying electrically generated images. A variety of factors must be accounted for to produce a desirable display. One of those factors is the brightness or shading level on the screen.
- One way of controlling screen shading is known as frame modulation. Frame modulation techniques have several advantages, however, they do not always optimize power consumption. More recently, visual displays have been used with portable devices, which necessarily are powered by a battery or a similar portable energy source.
- This invention is a system and method for saving power and reducing drive load variation when powering a screen display that includes varying brightness levels.
- the method of this invention includes several basic steps. First, a total number of screen pixels that must be energized to realize an electrically generated image across a screen is determined on a row-by-row basis. A specific order of energizing selected ones of the screen pixels is determined, based upon the total number of screen pixels that must be energized. Then the total number of screen pixels are energized selectively in the specific order that has been determined.
- a frame modulation technique includes displaying the image in a sequence of frames that are each divided into a plurality of energization periods.
- An order of energization is determined by arranging the total number of rows of pixels to be energized among the energization periods.
- Figure 1 is a schematic illustration of a system designed according to this invention.
- Figure 2 is a flow chart diagram illustrating a method of this invention.
- Figure 3 schematically illustrates possible implementations of a method of this invention.
- Figure 1 schematically illustrates a visual display system 20 including a display screen 22, which preferably is an electroluminescent display screen.
- the display screen 22 is divided into a plurality of pixels 24.
- the screen pixels 24 are arranged in a matrix of columns and rows. Each pixel is defined by an intersection between a row electrode and a column electrode.
- Row drivers and column drivers which are useful for electroluminescent displays, are well known to those skilled in the art. Only a portion of the matrix of screen pixels is schematically illustrated in Figure 1.
- the screen display 22 is coupled, through a conventional wiring arrangement 26, to a controller 28.
- the controller 28 preferably is a microprocessor.
- a plurality of control modules are schematically illustrated in Figure 1.
- a first module 30 processes data within the controller 28 to determine the content of an image to be displayed on the screen 22.
- a second module 32 controls the row and column drivers to energize the screen pixels to cause a display to be shown on the screen 22.
- a third module 34 selectively controls the supply of the energization voltages to the row and column drivers and, therefore, the screen pixels while the display is being shown on the screen 22.
- a fourth module 36 includes memory for storing information regarding various displays to be shown on the screen 22. Communication between the various modules within the controller 28 is schematically illustrated by the communication lines 38 through 48.
- FIG. 2 illustrates the basic method of this invention in flow-chart form.
- the flow-chart 50 includes a first step 52 where the controller 28 determines the total number of pixels for each brightness level that must be energized on a row-by-row basis to realize a desired image brightness. Then, at 54, a specific order of energizing the pixels is determined that will maximize efficient power usage, reduce drive load variation or both. Once the order is selected, the pixels are accordingly energized at 56.
- Frame modulation techniques are well known in the art.
- Figure 3 includes a chart 60 that schematically illustrates possible implementations of a preferred method of this invention when using a frame modulation technique.
- the chart 60 includes a matrix of columns and rows.
- the first column 62 indicates varying brightness levels for gray shades.
- the brightness level of a particular screen pixel can vary from dark to high brightness.
- Each column of the chart 60 (with the exception of the column 62) can be considered as a frame.
- the image is generated in a sequence of frames through time.
- Each frame is subdivided into three energization periods or energization states 64, 66 and 68, for example.
- Each energization period corresponds to a time when all of the screen pixels in a particular row are potentially energized or turned on. In the illustrated example, the pixels are energized between zero and three times per frame.
- a pixel that is to remain dark during the frame 63 is not energized during any one of the energization periods. Accordingly, three zeros are shown in Figure 3.
- a pixel that is to have a maximum or high brightness level is energized during each one of the energization periods 64, 66 and 68. That is indicated in Figure 3 by a series of ones. Accordingly, the ones and zeros in Figure 3 indicate a pixel being energized or not energized, respectively, during each energization period of each frame.
- FIG. 3 Only four sample pixels are illustrated in Figure 3. In a typical display screen 22, however, there may be thousands of pixels arranged in rows. The scenario illustrated as case 1 in Figure 3 is not necessarily efficiently consuming power. For example, in an embodiment where there are a large number of low and medium brightness leveled pixels, there will be a large load variation between the third energization period of one frame and the first energization period of a subsequent frame.
- a system designed according to this invention seeks to maximize the efficiency of power consumption by selectively arranging the order in which the pixels are energized during each frame.
- the two main benefits of using a system and method according to this invention are saving power and/or reducing drive load variation when using a frame modulation technique to effect varying brightness levels on a display screen.
- Equation 1 This invention incorporates the realization of a predictable relationship between modulation power and the percentage of screen pixels that are energized at any given time.
- P M (x) is the relative modulation power and x is the fraction of screen pixels that are energized at a given time.
- Equation 1 also quantifies the relative capacitive load on the column driving matrix used to power the display screen because the drive power is proportional to the capacitance.
- the row drivers of the display screen 22 effectively experience an impedance.
- Vr equals the row voltage
- Vc the column or modulation voltage
- Equation power term the horizontal or line frequency.
- the modulation power term the shape of the curve of equation 2 varies with panel size and aspect ratio. Importantly, the total power curve is not symmetrical about a point corresponding to fifty percent of the pixels being energized. An example total power curve is shown at 102 in Figure 4. Efficient power consumption appears to be achieved primarily by having less than fifty percent of all screen pixels energized at any given time.
- Figures 5 and 6 graphically illustrate the percentage of pixels turned on or energized within each row.
- the illustration in Figure 5 shows an example realization of an image where the energization strategy includes case 1 from Figure 3.
- the plot 104 corresponds to the energization state 64 while the plots 106 and 108 correspond to the energization states 66 and 68, respectively.
- the same brightness levels are achieved as were achieved in case 1 in column 63.
- the order of energization of the pixels has been rearranged. Specifically, the first energization state 72 includes three pixels being energized, the second energization state 74 includes one pixel being energized and the third energization state 76 includes two pixels being energized.
- Such a strategy for energizing the pixels may not necessarily provide a reduction in power consumption compared to the scenario in column 63, however, it may accomplish that result in combination with another one of the cases illustrated in Figure 3.
- the arrangement of pixel energization includes having one frame 70 followed by a second frame 78 that is, in turn, followed by a frame 70, etc.
- the order of pixel energization follows energization states 72, 74, 76, 80, 82 and 84.
- the energization state 84 is then followed by the energization state 72 and this process is cyclically repeated as required for generating the display on the screen 22.
- this embodiment includes a symmetric drive scheme.
- the symmetric drive scheme includes alternating a voltage polarity associated with the row drivers between a negative and positive polarity, respectively.
- the voltage polarity is alternated on an energization period-by-energization period basis, in this example.
- a negative polarity voltage has a lower magnitude than a positive polarity voltage by an amount equal to the magnitude of the column-writing voltage.
- case 4 i.e. , column 70
- case 8 i.e. , column 78
- the first energization state 72 includes a voltage having a negative polarity
- three pixels are energized during that energization period.
- Two pixels are energized during the energization period 76 and three pixels are energized during the energization period 82, respectively.
- the energization periods 74, 80 and 84 all have a voltage associated with them that has a positive polarity. Accordingly, it is advantageous to have fewer pixels energized during those energization periods. In other systems it will be more advantageous to have a greater number of pixels energized each time that a voltage having a positive polarity is generated. Accordingly different cases from Figure 3 may be utilized.
- case 3 which is illustrated in column 86, the order of pixel energization is arranged such that two pixels are energized during each energization period. Having an equal number of energized pixels during each energization period ensures that one-half of the pixels are energized at all times.
- the modulation power in this example is at its theoretical maximum.
- the system ensures that a difference between the number of energized pixels in any two energization states does not exceed a preselected maximum. All of these functions are accomplished by the controller 28. Given the above description, one skilled in the art can develop specific code to program the controller 28 for implementing the techniques of this invention. Similarly, one skilled in the art will now be able to choose from among commercially available microprocessors or to develop dedicated circuitry that will serve as the controller 28.
Abstract
Description
Claims
Priority Applications (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP53441798A JP2001509284A (en) | 1997-01-21 | 1998-01-08 | Power Consumption Control of Visual Screen Display by Determining the Order of Pixel Activation |
EP98901719A EP0954843A1 (en) | 1997-01-21 | 1998-01-08 | Power consumption control for a visual screen display by determing an order of pixel energization |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
US08/784,616 | 1997-01-21 | ||
US08/784,616 US6160541A (en) | 1997-01-21 | 1997-01-21 | Power consumption control for a visual screen display by utilizing a total number of pixels to be energized in the image to determine an order of pixel energization in a manner that conserves power |
Publications (1)
Publication Number | Publication Date |
---|---|
WO1998032116A1 true WO1998032116A1 (en) | 1998-07-23 |
Family
ID=25133009
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/US1998/000267 WO1998032116A1 (en) | 1997-01-21 | 1998-01-08 | Power consumption control for a visual screen display by determining an order of pixel energization |
Country Status (4)
Country | Link |
---|---|
US (1) | US6160541A (en) |
EP (1) | EP0954843A1 (en) |
JP (1) | JP2001509284A (en) |
WO (1) | WO1998032116A1 (en) |
Cited By (4)
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WO2001082284A1 (en) * | 2000-04-26 | 2001-11-01 | Ultrachip, Inc. | Low power lcd driving scheme |
EP1204262A2 (en) * | 2000-11-01 | 2002-05-08 | Kabushiki Kaisha Toshiba | Radio telephone apparatus and method for controlling the number of display colours thereof |
US7362294B2 (en) | 2000-04-26 | 2008-04-22 | Jps Group Holdings, Ltd | Low power LCD with gray shade driving scheme |
US10265385B2 (en) | 2016-12-16 | 2019-04-23 | Novo Nordisk A/S | Insulin containing pharmaceutical compositions |
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US6934772B2 (en) | 1998-09-30 | 2005-08-23 | Hewlett-Packard Development Company, L.P. | Lowering display power consumption by dithering brightness |
US6597351B2 (en) * | 2000-12-14 | 2003-07-22 | Nokia Mobile Phones Limited | Mobile communication device with display mode control |
US7002593B2 (en) * | 2001-11-01 | 2006-02-21 | Eastman Kodak Company | Method for reducing the power used by emissive display devices |
US20030222866A1 (en) * | 2002-05-30 | 2003-12-04 | Eastman Kodak Company | Display driver and method for driving an emissive video display in an image displaying device |
TW200410187A (en) * | 2002-12-09 | 2004-06-16 | Delta Optoelectronics Inc | LED display and driving method thereof |
US20040158878A1 (en) * | 2003-02-07 | 2004-08-12 | Viresh Ratnakar | Power scalable digital video decoding |
US7289256B2 (en) * | 2004-09-27 | 2007-10-30 | Idc, Llc | Electrical characterization of interferometric modulators |
US20070052671A1 (en) * | 2005-09-02 | 2007-03-08 | Hewlett-Packard Development Company Lp | Pixel element actuation |
US7633405B2 (en) * | 2005-11-14 | 2009-12-15 | Inova Solutions, Inc. | Low power LED visual messaging device, system and method |
US7982698B2 (en) * | 2005-11-14 | 2011-07-19 | Inova Solutions, Inc. | Low power LED visual messaging device, system and method |
US20090051369A1 (en) * | 2007-08-21 | 2009-02-26 | Qualcomm Incorporated | System and method for measuring adhesion forces in mems devices |
BRPI0908803A2 (en) * | 2008-02-11 | 2015-07-21 | Qualcomm Mems Technologie Inc | Device and method of sensing, measuring or characterizing screen elements integrated with the screen drive scheme |
EP2252899A2 (en) * | 2008-02-11 | 2010-11-24 | QUALCOMM MEMS Technologies, Inc. | Methods for measurement and characterization of interferometric modulators |
US8258800B2 (en) * | 2008-02-11 | 2012-09-04 | Qualcomm Mems Technologies, Inc. | Methods for measurement and characterization of interferometric modulators |
US8027800B2 (en) * | 2008-06-24 | 2011-09-27 | Qualcomm Mems Technologies, Inc. | Apparatus and method for testing a panel of interferometric modulators |
US8035812B2 (en) * | 2009-03-24 | 2011-10-11 | Qualcomm Mems Technologies, Inc. | System and method for measuring display quality with a hyperspectral imager |
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-
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- 1998-01-08 WO PCT/US1998/000267 patent/WO1998032116A1/en not_active Application Discontinuation
- 1998-01-08 EP EP98901719A patent/EP0954843A1/en not_active Withdrawn
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WO1990012388A1 (en) * | 1989-04-10 | 1990-10-18 | Cirrus Logic, Inc. | Method and apparatus for producing perception of high quality grayscale shading on digitally commanded displays |
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WO2001082284A1 (en) * | 2000-04-26 | 2001-11-01 | Ultrachip, Inc. | Low power lcd driving scheme |
US7362294B2 (en) | 2000-04-26 | 2008-04-22 | Jps Group Holdings, Ltd | Low power LCD with gray shade driving scheme |
EP1204262A2 (en) * | 2000-11-01 | 2002-05-08 | Kabushiki Kaisha Toshiba | Radio telephone apparatus and method for controlling the number of display colours thereof |
EP1204262A3 (en) * | 2000-11-01 | 2004-03-24 | Kabushiki Kaisha Toshiba | Radio telephone apparatus and method for controlling the number of display colours thereof |
US10265385B2 (en) | 2016-12-16 | 2019-04-23 | Novo Nordisk A/S | Insulin containing pharmaceutical compositions |
Also Published As
Publication number | Publication date |
---|---|
JP2001509284A (en) | 2001-07-10 |
US6160541A (en) | 2000-12-12 |
EP0954843A1 (en) | 1999-11-10 |
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