US005841431A
`5,841,431
`(114) Patent Number:
`United States Patent 55
`Simmers
`[45] Date of Patent:
`Nov. 24, 1998
`
`
`
`[54] APPLICATION OF SPLIT- AND DUAL- D. 374,227 10/1996 Williams 20.0...cceseeeeecereeeeee D14/138
`
`SCREEN LCD PANEL DESIGN IN
`D. 377,341
`1/1997 Imai et al. eececceeeeeeeeeees D14/138
`CELLULAR PHONES
`4,816,816
`3/1989 Usui .
`5,189,632
`2/1993 Paajanen et al. oe 364/705
`5,392,058
`2/1995 Tagawa occ
`cseeees 345/104
`
`[75]
`
`.
`
`.
`
`:
`
`Inventor: Charles Russell Simmers, Phoenix,
`
`5,410,329
`
`4/1995 Tagawaet al. vecsssesssseseenen 345/104
`
`
`
`:
`[73] Assignee:
`
`.
`.
`:
`Intel Corporation, Santa Clara, Calif.
`
`cseeees 345/104
`7/1996 Tagawa woes
`5,534,892
`8/1996 Tsunoda et al. oe 395/750
`5,548,765
`9/1997 Ishikawa et al. sssssssssseseen 345/98
`5,663,745
`Primary Examiner—Steven J. Saras
`.
`Assistant Examiner—David L. Lewis
`[21] Appl. No.: 749,486
`Attorney, Agent, or Firm—Blakely, Sokoloff, Taylor &
`[22]
`Filed:
`Nov. 15, 1996
`Zafi
`[51] Unt. C1.
`icccssssnenseee G09G 5/00; GO9G 3/36,
`ABSTRACT
`GO6F 1/00; GO6F 1/16
`~——*([57]
`aeeceesccesseseeeees 345/211; 345/103; 364/705.05;
`An apparatus for conserving power in information devices
`[52] USS. Cl.
`364/707; 364/708.1
`.
`with dual functions. A single display panelis logically split
`[58] Field of Search occ 345/211, 103,
`into two sub-panels. Each sub-panel can be powered up or
`345/104, 98, 100, 131, 156, 173, D14/137,
`downseparately as is required by the function of the device.
`138; 364/705.05, 707, 708.1, 379/433,
`The display panel has a plurality of improved segment
`428, 440, 395/750, 750.04; 455/556, 566,
`drivers which are provided powersignals enablingthe set of
`574, 575, 89, 90
`segment drivers corresponding to a sub-panel to be sepa-
`rately powered. In systems with two separate display panels,
`each of the panels may be powered up or down bythe use
`of similar improved segment drivers as necessary.
`
`[56]
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`D. 370,673
`
`6/1996 Happoet al.
`
`..eceeeseceseeeees D14/138
`
`11 Claims, 6 Drawing Sheets
`
`SHARED MEMORY
`
`510
`
`PRIMARY
`GRAPHICS
`LCD
`
`ADDRESS__BUS
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`
`HOSTOoLagDATA aus aCONTROL BUS
`
`
`SECONDARYLCDPANEL
`
`BUS CONTROL HANDSHAKE(REQUEST/GRANT)
`
`
`CONTROL
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`
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`560
`
`Page | of 12
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`GOOGLEEXHIBIT 1017
`
`GOOGLE EXHIBIT 1017
`
`Page 1 of 12
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`

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`U.S. Patent
`
`Nov. 24, 1998
`
`Sheet 1 of 6
`
`5,841,431
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`
`
`640X240DOTMATRIXLCDPANEL
`
`SEGMENTIMPUTS1TO640
`
`
`DISPDATA(O-3) 150
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`FIG.1(PRIORART)
`
`Page 2 of 12
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`Page 2 of 12
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`

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`U.S. Patent
`
`Nov. 24, 1998
`
`Sheet 2 of 6
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`5,841,431
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`Page 3 of 12
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`Page 3 of 12
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`U.S. Patent
`
`Nov. 24, 1998
`
`Sheet 3 of 6
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`U.S. Patent
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`Nov. 24, 1998
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`Sheet 4 of 6
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`U.S. Patent
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`Nov. 24, 1998
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`Sheet 5 of 6
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`5,841,431
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`Page 6 of 12
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`U.S. Patent
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`Nov. 24, 1998
`
`Sheet 6 of 6
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`5,841,431
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`Page 7 of 12
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`5,841,431
`
`1
`APPLICATION OF SPLIT- AND DUAL-
`SCREEN LCD PANEL DESIGN IN
`CELLULAR PHONES
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`2
`into two or more logical sub-panels, each of which has
`corresponding drivers which output pixels to their portion of
`the display, and are independently powered-up or down as
`the application requires.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
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`FIG. 6 is a system diagram of a computer system with a
`split-screen LCD panel according to one embodimentof the
`invention.
`
`FIG. 1 is an operational diagram of a typical LCD display
`invention relates to the field of display
`The present
`according to the prior art.
`devices. More specifically, the present invention relates to
`FIG. 2 is an operational diagram of a split screen LCD
`graphical displays connected to information devices.
`display according to one embodimentof the invention.
`2. Description of Related Art
`FIG. 3 is an illustration of howasplit screen LCD display
`In high-end “smart” cellular phones, which function both
`may be utilized in a information device.
`for telecommunications and for storing and retrieving infor-
`FIG. 4 is an operational diagram of a dual screen LCD
`mation (e.g., a Personal Digital Assistant (information
`display according to one embodimentof the invention.
`device)), it is often necessary to provide two displays, one
`for each function. The smaller of the displays, used for the
`FIG. 5 is a system diagram of a computer system with a
`telecommunications function, commonly consists of
`dual LCD panel display system according to one embodi-
`ment of the invention.
`between ten and twenty characters across (columns) and
`three to eight rows. The larger of the displays, used for the
`information device function, is a graphical display with a
`resolution of typically 640 pixel columns across by 240
`pixel rows.
`Traditionally, each display was treated as a separate
`system since the smaller display operates continuously,
`while the larger display operates more sparingly. In periods
`of non-use,
`the large display is powered-down.
`Disadvantageously, each display has its own controller to
`convert
`information into displayable pixels and its own
`integrated circuits which drive the pixels to be output on the
`display panels.
`In battery-operated and power-conscious
`devices such as PDAs,the redundancy of having twosets of
`drivers, integrated circuits and controllers is expensive and
`can also increase the mean-time-between-failure for the
`devices. Further, where a single display is used for both
`functions, the entire display must be active, even when only
`a small sub-panel of the display is required to operate(i.e.,
`for telecommunications). In such a circumstance, the power
`drain is excessive for the function served, and, therefore,
`highly inefficient.
`Thus, there is a need to reduce the power drain of such
`devices by allowing independent operation of only one
`display, in the case of two separate displays, and a sub-panel
`in the case of single physical display.
`
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`SUMMARY
`
`In the case of some dual-function information devices
`
`such as a cellular phone with PDA, two separate physical
`displays are controlled by a single video controller. The
`video controller provides a plurality of control signals to
`drivers which drive pixels onto the displays. The invention
`provides a power control block which is coupled to those
`drivers to selectively power-downdrivers for the larger of
`the two displays, while keeping powered-up the smaller of
`the displays. The power control block can be programmed
`by a user/software to power-up or power downthe displays
`as dictated by the use of the Information device. The power
`control block is, therefore, coupled to a CPU or other such
`processor from which it receives commands regarding
`which display to keep powered-up and which to power
`down.
`
`Alternatively, in dual-function information devices where
`there is only one physical display for the information device,
`a similar power control block can be programmed by
`instructions being entered by the CPUto selectively power-
`downcertain pixel drivers for the display and thereby create
`a logical “sub-panel”. A single display screen may besplit
`
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`DETAILED DESCRIPTION OF THE DRAWINGS
`
`FIG. 1 is an operational diagram of a typical LCD display
`according to the prior art.
`FIG. 1 shows a 640 by 240 dot-matrix liquid crystal
`display (LCD)panel 100 whichis driven by two inputs 1100
`and 1150 for rows running down the vertical axis of panel
`100 and also by four inputs—1200, 1220, 1240 and 1260—
`driving pixels in columnsacross the horizontal axis of panel
`100. Thus, on a 640 by 240 pixel display such as LCD panel
`100, input 1100 is responsible for the first 120 rowsof pixels
`and input 1150 is responsible for the last 120 rowsofpixels.
`For LCD panel 100, input 1200 drives the first 160 columns
`of pixels, input 1220 the second 160 columnsofpixels, input
`1240 the third 160 columnsofpixels and input 1260 the last
`160 columns of pixels of LCD panel 100. LCD panel 100
`may be used on a notebook computer, a personal digital
`assistant (PDA), cellular phoneor for use in any information
`device capable of utilizing an LCD output.
`The output of such LCD panels are typically driven by
`“segment” drivers driving the pixel columns on the hori-
`zontal axis and by “common” drivers which enable pixel
`rowsonthe vertical axis of the panel. The physics of driving
`pixel output on display panels is well-known in the art and
`will not be described in depth. Common driver 110 and
`common driver 115 generate input signal 1100 and input
`signal 1150, respectively, while segment driver 120, seg-
`mentdriver 122, segment driver 124 and segmentdriver 126
`generate input signals 1200, 1220, 1240 and 1260, respec-
`tively. Each of these segment drivers convert serial data into
`parallel data and generate for output level translator signals
`which map an incoming digital signal into certain voltage
`levels which the LCD panel converts into pixel intensities
`based on the voltage level differentials. The common drivers
`activate a particular row for displaying output generated by
`the segmentdrivers.
`Also shown in FIG. 1 are several control signals origi-
`nating from the display controller of the cellular phone,
`information device or computer system that utilize the
`display capability of LCD panel 100. Shown are a display
`off control
`(DISPOFF) signal 140,
`a display data
`(DISPDATA)signal 150, a display clock (DISPCLK)signal
`160, a line latch clock (LLCLK)signal 170, and a first line
`marker (FLM)signal 180. Also input to the drivers are two
`voltage signals, VL 197 and VSS 190. These voltage signals,
`
`Page 8 of 12
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`5,841,431
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`3
`VL 197 and VSS 190, can be used to indicate different logic
`levels to the pins they supply.
`DISPDATA 150 is a signal comprised of four or eight
`bits—0, 1, 2 and 3 or 0 through 7—whichare transmitted in
`parallel and representlight/color intensity levels to be output
`on LCD panel 100 and originates from a display controller
`device. DISPDATAdeviate 150 is output on LCD panel 100
`with bit 0 in the upper left corner of the screen andbits 1,
`2 and 3 output on the same row from left to right starting
`after bit 0. The serial to parallel conversion of DISPDATA
`150 is carried out by the timing signal DISPCLK 160 which
`originates from a clocking mechanism. DISPCLK 160
`clocks the 4 bits of DISPDATA 150 into shift registers
`contained in the segmentdrivers. Once the shift registers in
`segment driver 120 are full, then another or similar clocking
`mechanism asserts the line latch clock (LLCLK) 170 signal
`to common driver 110. As shown in FIG. 1, the line latch
`clock is also connected to a latch pulse (LP) pin or input on
`segment drivers 120, 122, 124 and 126, such that when the
`shift registers are filled with bits of display data and the
`LLCLKsignal 170 has been asserted, the bits stored in the
`shift registers are latched and transferred over input line
`1200 to LCD panel 100. The LLCLK signal 170 which
`essentially loads an entire row of pixels to LCD panel 100,
`also clocks the common driver incrementing the shift reg-
`ister of the common driver 110 by one such that the LCD
`panel can enable the next row of the panel for pixels driven
`by the segment drivers once a row has been completed.
`DISPDATA 150 transmits a four-bit signal (in parallel),
`corresponding to four pixels for the LCD panel,
`to the
`segment drivers.
`Once all of the rows of pixels have been output in this
`manner, such that the display of pixels is completed for one
`image frame, a first line marker (FLM) signal 180 is again
`asserted, which is also clocked with the line latch clock
`LLCLK 170. First
`line marker signal 180 propagates
`throughall of the shift registers of all common and segment
`drivers resetting the shift registers to zero, such that the
`commondriver 110is set to enable the next new row ofpixel
`data to be output by the segmentdrivers. Likewise, segment
`drivers 120, 122, 124, 126 are also reset to receive the next
`set of pixel data from DISPDATA 150.
`The DISPOFFsignal 140 shownin FIG. 1, when driven
`active, disables the output for all pins and thereby blanks
`LCDpanel 100 such that no pixels are output to the panel.
`FLM 180 is also divided by two bya divider circuit 185 to
`periodically reverse the polarity of the pins where inputs
`1200, 1220, 1240, 1260 and inputs 1100 and 1150 are output
`by the segment and commondrivers. Periodically, reversing
`polarity is necessary because the typical LCD requires an
`alternating current (AC) signal such that the liquid crystal
`does not “plate-out” against the electrodes and turn black.
`Thus,
`the FR pin is periodically reversed and sets the
`internal shift registers at one, rather than zero. Other pins
`shownin the segment drivers 120, 122, 124 and 126 are an
`XCK pin, which receives the DISPCLK signal 160, the
`DISPOFFpin, which receives the DISPOFFsignal 140, and
`an output pin labeled Y1-Y160, which transmits the pixels
`whichare stored in the shift registers of the segment drivers
`to the LCD panel 100. Also shown in FIG. 1 are external
`input/output expansion pins EIO-1 and EIO-2 for each of the
`segment drivers 120, 122, 124 and 126.
`The expansion pins EIO-1 and EIO-2 are connected
`together such that the EIO-1 pin of segment driver 120 loads
`a ground or loads a negative voltage value from EIO-1 of
`segment driver 120 to EIO-2 of segment driver 122, indi-
`cating that the first 160 pixels have been output by segment
`
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`driver 120 and that the next 160 pixels of the row may be
`output by segment driver 122. This daisy-chaining is pro-
`vided also for the segment drivers 122 to 124 and 124 to 126
`by propagating either ground/negative value to these seg-
`ment drivers to complete the pixel row. Likewise, on com-
`mon drivers 110 and 115 are pins DIO-1 and DIO-2, which
`are daisy-chained together such that whenthefirst 120 rows
`of pixels enabled by common driver 110 are completed,
`common driver 115 receives the remainder of the data and
`completes pixel rows 121 through 240. The FR pin, or frame
`pulse pin, of commondrivers 110 and 115 operate similarly
`to the FR pins of segmentdrivers 120, 122 124 and 126 and
`will not be described further. Likewise, the DISPOFFpins of
`the common drivers 110 and 115 operate similarly to the
`DISPOFFpins of segmentdrivers 120, 122, 124 and 126 and
`will not be described further. Common driver 110 has a CK
`pin whichis driven from LLCLK signal 170 and, in a given
`time index, represents the number of rows which have been
`output to the LCD panel 100. The SHL pin of the segment
`drivers 120, 122, 124 and 126, as well as the SHL pin of
`common drivers 110 and 115 serve to indicate in which
`direction pixels representing the image are output to the
`display, whether left to right, right to left or, in the case of
`the commondrivers, top to bottom, or bottom to top.
`Further, a mode pin is provided on all of the segment
`drivers and the common drivers which, when input a certain
`logic level from VSS 190, indicates a mode in which the
`drivers operate. VL 197 is shown as an input level to the
`SHL pins of the segment drivers and by its logic level
`indicates what direction the image is being output in. The
`physics underlying the liquid crystal display is well known
`in the art and will not be described so as not to obscure the
`invention. According to the prior art, therefore, the entire
`bank of segment drivers 120, 122, 124 and 126 is always
`powered-up and enabled for output. There is no signal or
`mechanism to powerseparately, any of the segmentdrivers.
`Thus, when only a portion of the panel has displayable
`output such as when the information device functions as a
`telecommunications device, the power consumedbytherest
`of the panel and their segment drivers is wasted.
`FIG. 2 illustrates an operational diagram of a split screen
`LCDpanel according to one embodimentof the invention.
`All pins of the segment and commondrivers, input and
`control signals which toggle them as described with respect
`to FIG. 1 with identical reference numbers operate similarly
`with regard to this embodimentof the invention and will not
`be repeated. However, the invention provides for additional
`control by way of VCC pins on each of the segmentdrivers
`as well as splitting VCC into separate signals VCC1 195 and
`VCC2 193. Thus, a typical segment driver circuit would
`need to be modified as follows to provide for split panel
`LCDoperation.
`According to the embodiment shown in FIG. 2, a single
`640 by 240 resolution dot matrix LCD panel 200, which is
`similar to the 640 by 240 resolution LCD panel 100 of FIG.
`1, is split logically into a 160 by 240 size sub-panel 210 and
`a 480 by 240 size sub-panel 204. By logically splitting a
`single LCD panelinto two sub-panels, it is possible to save
`power by powering down the sub-panel of LCD panel 200
`whichis not being used. As shown in FIG. 1, the DISPOFF
`signal powers down the entire panel and does not allow
`powering downa sub-panel(i.e., certain segment drivers) of
`the entire panel. The power savings results from certain of
`the segmentdrivers no longer being clocked and no longer
`consuming power. Further power savings and probably the
`greater proportion of power savings is gained from not
`having to drive or toggle the states of the pixels in sub-panel
`204.
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`Page 9 of 12
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`Page 9 of 12
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`5,841,431
`
`5
`The invention provides an improved segmentdriver cir-
`cuit with the capability of being enabled or powered inde-
`pendentof other segmentdrivers. Specifically, a VCC pin is
`provided to each of the modified segment drivers 120a,
`122a, 124a and 126a. These VCC pins are the positive
`powerrails to each segmentdriver.
`As shown in FIG. 2, sub-panel 202 has all 240 rows of
`pixels but occupies only 120 pixel columns. Thus, to inde-
`pendently operate sub-panel 202, only segmentdriver 120a,
`which drives the first 120 pixel columns(see description of
`similar driver 120 of FIG. 1), needs to be controlled.
`Therefore, the invention provides control of VCC2 193
`coupled to the VCC pin of segment driver 120a. When
`VCC2 193 is enabled (on), the VCC pin on segmentdriver
`120a will power-on the segment driver to output pixels.
`When VCC2 193 is disabled (switched off), the segment
`driver 120a is powered-down or off and cannot drive pixel
`output to the display panel.
`Likewise, another signal VCC1 195 is coupled to the
`VCCpins of each segment drivers 122a, 124a and 126a,
`which drive pixels on the other sub-panel 204. When VCC1
`195 is on, the segment drivers 1224, 124a and 126aareall
`powered on and enabled to drive pixel output to the panel
`200 (in sub-panel 204). When VCC 195is off, all of the
`segmentdrivers 122a, 124a and 126a are powered down and
`cannot drive pixels to the display panel. The three segment
`drivers 1224, 124a and 126a all utilize a single source for
`their VCC pins since, according to the embodiment, they
`drive the same sub-panel.
`Thus, sub-panel 202 and sub-panel 204 are capable of
`being independently powered, and thereby selected by the
`use of separate signals. VCC1 195 and VCC2 193 will be on
`when both sub-panels must be powered. One skilled in the
`art will recognize that a single panel may be split into as
`many logical sub-panels as segment drivers will allow. In
`this case, panel 200 maybe split into four logical sub-panels,
`one for each segment driver, each segment driver powered
`by its own VCCsignal.
`The power source VCC1 195 and VCC2 193 are con-
`trolled from some software/hardware which selects the
`functionality of the panel, and therefore, indicates which
`sub-panels are to be powered (see power control block 660
`of FIG. 6).
`FIG. 3 shows the casing structure for an information
`device according to one embodimentof the invention. The
`information device is capable of functioning both as a
`cellular phone for telecommunications and as a PDA. The
`LCD panel 200, is split logically into sub-panel 204 and
`sub-panel 202. The information device has a top outer shell
`320 and a bottom outer shell 322 as well as a top inner shell
`310 and a bottom inner shell 312. Top inner shell 310 andits
`obverse side top outer shell 320 bounds and contains LCD
`panel 200 and is connected to joint 350 about which the top
`information device is able to fold. Likewise bottom inner
`shell 312 with its obverse side bottom outer shell 322, is also
`able to fold about joint 350. Bottom inner shell 312 and
`bottom outer shell 322 may both contain input keys such as
`alpha-numeric and function keys with which a user can input
`data, make telephone calls and/or control operation of the
`information device. Top inner shell 310 has an open area 300
`which may be open aperture or some transparent panel
`which closed upon LCD panel 200, makesvisible the image
`in sub-panel 204, thus allowing monitoringofthe friction for
`which sub-panel 202 is intended.
`The information device is “closed” when bottom inner
`
`shell 312 and top inner shell 310 abut one another by folding
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`the Information device about joint 350. When the informa-
`tion deviceis closed, the open area 300 closely abuts the area
`of sub-panel 204 such that the image contents (pixels) on
`output sub-panel 204 are visible to the user. When closed,
`the outer shell 320, which may or may not be transparent
`(excepting open area 320), covers sub-panel 202 which is
`contained in inner shell 312. Upon closing the information
`device, a switch, relay or contact disposed about or within
`joint 350 will operate to power down the driver(s) for
`sub-panel 202 while leaving the driver(s) for sub-panel 204
`powered-up. This relay or contact will toggle the VCC pins
`of the appropriate segment drivers as discussed in FIG. 2.
`Thus, when the information device is closed, sub-panel 204
`is operational while sub-panel 202 is disabled thereby saving
`powerand screen life. This still allows the user to monitor
`the telecommunications function of the information device.
`
`Further, by using one physical display rather than two
`separate physical displays, the information device saves by
`reducing device complexity and cost.
`As shownin FIG. 3, when closed, sub-panel 204 shows a
`telephone number, a “BAT”indicator indicating the level of
`battery life in the device and a “SIG”indicator all which are
`still visible to the user. Underneath,
`the portion of LCD
`panel 200 covered by outer shell 320, 1.e., sub-panel 202, is
`powered down and inoperative. Thus, the telecommunica-
`tions display of the information device can be viewed on a
`sub-panel while the information device one display is closed
`and data sub-panel is powered down.
`When the information device is in the “open” position,
`both sub-panels 202 and 204 are powered. In this mode, both
`the data function and telecommunications functions can be
`displayed on panel 200. Thus, all segment drivers are
`powered when the Information device is open.
`In this
`embodiment,
`the selection of individual sub-panels via
`software is not needed since the position of the information
`device makes the selection.
`
`FIG. 4 shows a information device with two separate
`displays, according to one embodimentof the invention.
`Whenan information device, by design has two separate
`displays located on different physical planes, the invention
`provides for powering down onedisplay, while keeping the
`other active, depending on what functionis being carried out
`on the device. Shown in FIG. 4 is a first LCD panel 100 and
`a second display LCD panel 400. LCD panel 400,if it is to
`use the same controller signals as the LCD panel 100, must
`have an equal numberof rows of pixels as LCD panel 100,
`and consequently, the same duty cycle. Without the same
`vertical resolution, the controller would need to refresh to
`the larger of the two resolutions thereby undermining bus
`bandwidth, memory resources and framerates.
`System software and the video controller would treat the
`combination of LCD panel 100, which has a 640 by 240
`resolution, and LCD panel 400 with a 160 by 240resolution,
`as a single logical panel of 800 by 240. Segmentdriver 420
`which drives LCD panel 400 receives the first set of the
`input data bits from DISPDATAsignal 150 and uponfilling
`its shift registers, propagates a daisy-chaining commandto
`segment driver 121. Segment driver 121 is modified from
`segment driver 120a of FIG. 2 in that the EIO2 pin is
`extended to EIO1 output pin of segment driver 420. VSSis
`now connected to EIO2 so that segment driver 420 receives
`the input stream before segment drivers of LCD panel 100.
`The separate display panels 100 and 400 are controlled
`similar to the split-screen (sub-panel) embodiment described
`above for FIG. 2. Each of the segment drivers 121, 123, 125
`and 127 of panel 100 and segment driver 420 is provided
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`with separate VCC pins. The invention also provides a
`powersource VCC2 493 coupled to the VCC pin of segment
`driver 420. When VCC2 493is on, the VCC pin on segment
`driver 420 will power-on the segment driver 420 to output
`pixels to panel 400. When VCC2 493 is off, the segment
`driver 420 is powered-downor off and cannot drive pixel
`output to panel 400.
`Likewise, another power source VCC1 495 is coupled to
`the VCC pins of each segmentdrivers 121, 123, 125 and
`127, which drive pixels on display panel 100. When VCC1
`495 is on, the segment drivers 121, 123, 125 and 127 are all
`powered on and enabled to drive pixel output to the panel
`100. When VCC1 495is off, all of the segment drivers 121,
`123, 125 and 127 are powered down and cannotdrive pixels
`to the display panel. The three segmentdrivers 121, 123, 125
`and 127 all utilize a single signal for their VCC pins since,
`according to the embodiment, they drive the same sub-panel.
`Thus, display panels 100 and 400 are capable of being
`independently powered, and thus, independently selected.
`VCC1 495 and VCC2 493 will be on when both display
`panels must be powered.
`FIG. 5 is asystem diagram of a computer system in which
`a dual LCD panel display system according to one embodi-
`mentof the invention may beutilized.
`FIG. 5 shows well known elements of a computer system
`such as a host CPU 520, a shared memory 510 and a display
`controller 530. In this embodiment, LCD display controller
`530 drives and controls a primary graphics LCD display
`panel 540 and a secondary LCD panel 550. Display con-
`troller 530 provides the signals shown in FIG. 4 such as
`DISPDATA 150. Specifically, display data 535 of FIG. 5
`corresponds to DISPDATA 150 of FIG. 4 and control clocks
`537 of FIG. 5 refer to all other controller signals, such as
`FLM 180 which are provided to the LCD. Primary graphics
`LCDdisplay panel 540 and secondary LCD panel 550 are
`shownas single blocks in FIG. 5, but include all necessary
`segment drivers and common drivers, as well as internal
`input lines and dividers, as shownin FIG. 4 to enable output
`to the actual LCD panels.
`Shared memory 510 services both host CPU 520 and LCD
`display controller 530 by way of an address bus 524.
`Address bus 524 carries memory addresses of shared
`memory 510 to/from CPU 520 and display controller 530.
`Data bus 526 is capable of sending and receiving to either
`the CPU 520 or the display controller 530. Data bus 526
`delivers raw data to the LCD display controller 530 from
`which display controller 530 can generate actual display
`data 535 which are pixels to be output on LCD panels 540
`and 550. Control bus 528 is used to control the flow of
`information from shared memory 510 which is delivered
`over data bus 526. A bus control (handshake) line transmits
`request and grantpairsto arbitrate use of the address, control
`and data bus between CPU 520 and display controller 530.
`CPU 520 is a central processing unit, such as the Intel
`Pentium™processor and is capable of processing informa-
`tion according to code delivered to it by software or hard-
`ware through data bus 526, address bus 524 and control bus
`528. The structural detail and functioning of CPU 520 as
`well as shared memory 510, display controller 530, address
`bus 524, data bus 526 and control bus 528 are well known
`to one reasonably skilled in the art of computer systems and
`will not be described further.
`
`FIG. 5 shows a key feature of the invention which is
`powercontrol block 560. Power control block 560 may be
`composed of multiplexers, switches, and transistors and is
`implemented in accordance with the specifications of CPU
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`520 and system architecture. Power control block 560 cen-
`trally controls the selection and thus, powering of primary
`LCDpanel 540 and secondary LCD panel 550 through the
`use of selector lines 562 and 564. Power control block 560
`drives selector line 562 active when secondary LCD panel
`550 is to be enabled for output. If both primary display panel
`540 and secondary LCD panel 550 are to be enabled for
`output,
`then power control block 560 will also activate
`selector line 564, such that the primary graphics display
`panel 540 will also be enabled for output. In the case where
`the user or software only requests that secondary LCD panel
`550 be enabled but not primary LCD panel 540, the power
`control block 560 will deactivate selector line 564.
`
`The signals VCC1 495 and VCC2 493 of FIG. 4 may
`originate directly from selector lines 564 and 562, respec-
`tively. When selector lines 564 and 562 dictate that both
`panels 540 and 550 are to be enabled for output, VCC1 495
`and VCC2 493 of FIG. 4 will be enabled. Likewise, when
`only secondary LCD panel 550 is to be enabled, selector line
`564 can enable VCC2 493 and disable VCC1 495, thereby
`powering down the primary graphics LCD display panel
`540.
`
`CPU 520, when instructed that only the telecommunica-
`tions function of the information device is to be used, will
`send a command to power control block 560. A transistor-
`implemented switching mechanism or multiplexer will then
`drive selector line 562 active, while inactivating selector line
`564. The switching mechanism or multiplexer(s) are capable
`of necessary control signals from the CPU in responseto a
`change in function of the information device. The selector
`lines are independently switched on/off within the power
`control block allowing more control over power usage.
`FIG. 6 is a system diagram of a computer system in which
`a dual LCD panel display system according to one embodi-
`ment of the invention may beutilized.
`Where a split-screen LCD panel embodimentis desired,
`a system similar to that shown in FIG. 2 may be equipped
`so that selector lines 662 and 664 control enabling of certain
`segments by providing signals VCC1 195 and VCC2 193,
`respectively (see FIG. 1 and associated description). For
`instance, when both selector lines 662 and 664 set high both
`VCC1 195 and VCC2 193, all four segment drivers and,
`consequently, both sub-panels 643 and 645 will powered.
`When VCC2 193is set high (by selector line 662) and VCC1
`195 is set low, only segment driver 120 and consequently,
`sub-panel 645 will be powered. Within power control block
`660,
`the selector lines 662 and 664 are independently
`switched using transistor or multiplexors upon receiving
`commands from CPU 520 regarding device function.
`Power control block 660 which generates the signals on
`selector lines 662 and 664 is coupled to host CPU 520 and
`consists of components similar to those shown in and
`described for FIG. 5. Further, CPU 520, shared memory 510,
`address bus 524, data bus 526, control bus 528 and bus
`control handshake 529 operate similar to their counterparts
`shownin and described for FIG. 5 and will not be repeated.
`LCD display controller 630 of FIG. 6 may be slightly
`different from counterpart controller 530 in that controller
`630 has only one physical display to drive (as opposed to
`two) and thus, may not require the hardware/software com-
`plexity of controller 530 of FIG. 5.
`While the present
`invention has been particularly
`described with reference to the various figures, it should