a2, United States Patent
`US 6,661,426 B1
`(10) Patent No.:
`Jetha et al.
`(45) Date of Patent:
`Dec. 9, 2003
`
`
`US006661426B1
`
`(54) USER INTERFACE GENERATION
`(75)
`Inventors: Zeenat Jetha, Vancouver (CA);
`Johannes A. Jansen, Eindhoven (NL)
`
`(73) Assignee: Koninklijke Philips Electronics N.V.,
`Eindhoven (NL)
`
`
`
`6,429,883 B1 *
`8/2002 Plowetal. we. 345/768
`FOREIGN PATENT DOCUMENTS
`0840276 A2
`5/1998 eae G09G/5/14
`EP
`0840277 A2
`5/1998...
`... GO9IG/S/14
`EP
`0849946 A2
`6/1998"...
`... HO4N/7/08
`EP
`0901284 A2
`3/1999
`ow...
`... HO4N/7/08
`EP
`W09613120
`5/1996...
`... HO4N/S/45
`WO
`
`(*) Notice: Subject to any disclaimer, the term ofthis©WO W09623193 8/1996... w+ F42B/5/02
`
`
`patent is extended or adjusted under 35
`WO
`W09728499
`8/1997... w GO6F/9/00
`WO
`W09911060
`3/1999 a. HO4N/S/445
`U.S.C. 154(b) by 470 days.
`
`
`
`(21) Appl. No.: 09/668,335
`
`Filed:
`
`Sep. 22, 2000
`
`(22)
`
`(30)
`
`Foreign Application Priority Data
`
`* cited by examiner
`
`OTHER PUBLICATIONS
`
`Its Center
`Japan 09 148996A, “Broadcasting System,
`Device and Broadcasting Reception Equipment” (Abstrac).
`
`Sep. 25,1999
`Dec. 30, 1999
`
`(GB) cecescessessessessesssessssesesesssesseeass 9922627
`(GB) oo.ee eee eeeccceseeesscecneseneesensaees 9930786
`
`(SL) Unt. C0 eee ecccccccsecseeseeseeseereeseeseeneesees G09G 5/00
`
`(52) U.S. Ch oo.
`.... 345/629; 345/768
`
`(58) Field of Search oo...
`eee 345/629, 630,
`345/421, 640, 638, 639, 768, 848
`
`(56)
`
`References Cited
`U.S. PATENT DOCUMENTS
`
`12/1996 Nakazawa .......... 395/340
`5,590,265 A
`
`4/1997 Tsujimoto et al.
`.......... 395/135
`5,625,764 A
`10/1997 Bricklin ......, .. 345/119
`5,680,152 A
`
`1/1998 Schelling et al.
`.
`... 358/296
`5,706,097 A
`3/1999 Moon ...........
`.... 348/564
`5,877,817 A
`
`.... 345/340
`4/1999 Alexander
`.
`5,896,131 A *
`
`8/1999 Smith we w 345/339
`5,933,141 A *
`6,002,403 A * 12/1999 Sugiyamaet al.
`........... 345/335
`6,088,032 A *
`7/2000 Mackinlay ............0. 345/355
`
`Primary Examiner—Matthew Luu
`(74) Attorney, Agent, or Firm—Gregory L. Thorne
`
`(57)
`
`ABSTRACT
`
`An on-screen display generation apparatus (10) and method
`for controlling the same are provided, in which data from
`two or more independent sources (12, 16) is used by a
`windowscontroller (22) to generate and periodically update
`a respective display panel for each source based at least
`partially on data from that source. A display controller (28)
`is configured to generate output pixel values for display (32)
`based at least partially on contributions from two or more of
`the display panels (34, 36), with certain pixels having
`contributions from two display panels wherea first panel is
`positioned to at least partially overlie a second and the
`overlying part of the first panel is specified as translucent.
`
`14 Claims, 4 Drawing Sheets
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`86 —_
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`PROGRAMME Pony i
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`1
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`APPLE 1017
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`APPLE 1017
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`1
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`

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`U.S. Patent
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`Dec. 9, 2003
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`Sheet 1 of 4
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`US 6,661,426 B1
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`20
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`NET
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`T/
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`F
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`18
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`—{EMAI
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`WEB
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`16
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`z= 2
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`i
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`WINDOW CTL DISPLAYCT||
`i8
`DISPLAY
`aurrer
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`UI/F
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`44
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`130
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`10
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`{7} 38
`ty
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`34
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`2
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`U.S. Patent
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`Dec. 9, 2003
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`Sheet 2 of 4
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`US 6,661,426 B1
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`E-MAIL: HI!
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`PROGRAMME tS
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`ay
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`‘CAR HOMEPAGE
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`7
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`‘y
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`3
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`

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`U.S. Patent
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`Dec. 9, 2003
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`Sheet 3 of 4
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`US 6,661,426 B1
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`FIG. 3
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`4
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`

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`U.S. Patent
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`Dec. 9, 2003
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`Sheet 4 of 4
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`US 6,661,426 B1
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`5
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`US 6,661,426 B1
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`1
`USER INTERFACE GENERATION
`
`BACKGROUND OF THE INVENTION
`
`2
`By providing for the overlying portion of a display panel
`to be translucent, the features of the overlain panel can at
`least partially be seen, thereby making available to the user
`a greater volumeof data.
`The windowscontroller may be arranged to generate each
`display panel as a first portion and a second, attached,
`portion with only one ofthe first and second portions being
`specified as translucent. In such an arrangement, one of the
`sources may suitably comprise a source of video image
`frame sequences and the display panel for that source may
`then display the video image framesin the portion other than
`that specified as translucent. Also, such video image source
`may supply ancillary data to the video image frame
`sequences and the windowscontroller may then be arranged
`to generate content in the portion specified as translucent on
`the basis of said ancillary data.
`One of the sources may comprise a tuner capable of
`receiving broadcast television signals, and another maybeis
`a web browser configured to obtain from the Internet web
`pages relevant to a currently displayed broadcast television
`signal and to present any web pages so found in anatleast
`partially translucent panel overlying that panel on which
`images from the broadcast
`television signal are being
`shown.
`
`6
`
`The present invention relates to apparatuses having dis-
`play means operable to display data from two or more
`sources simultaneously, particularly but not exclusively in
`respective display panels or windowson a single screen or
`display device, and to methods for managing the presenta-
`tion and updating of such data displays.
`Such multiple source display apparatuses have become a
`relatively common feature in the past few years, with
`windows desktops on computers and picture-in-picture
`facilities on televisions being two well known examples.
`USS. Pat. No. 5,680,152 (Bricklin) describes a method and
`apparatus for navigating multiple independent windowed
`images on a computer display screen of a computer display
`system. Whilst the windows maybe of an arbitrary shape
`and size, Bricklin (in common with many other such
`systems) prefers that they be rectangular.
`An On Screen Display (OSD) system for a digital tele-
`vision set-top box is described in European patent applica-
`tion EP-A-0 840 277 (Texas Instruments). The OSD system
`described can simultaneously display different kinds of
`The display controller may be arranged to generate a two
`pictures, such as a bit-map, a graphic, a still video picture,
`dimensional
`image of a three dimensional environment,
`a motion video picture, or a background colour, with each in
`based on stored data defining said environment, from a
`a respective window. A random access memory device
`predetermined viewpoint within said environment, and with
`provides both CPU working memory and a store for the
`said display panels mapped onto surfaces within said envi-
`assembled windowsin the system of EP-A-0 840 277 with
`a window controller selectively reading contributions from
`ronment. With such an arrangement, user-operable input
`
`a selected windowtoafirst-in-first-out memory holding the means are preferably provided by operation of which the
`user is enabled to manoeuvrethe location and/or direction of
`bits required to display each pixel of the composed screen
`display.
`said viewpoint within the three dimensional environment.
`As hinted at by EP-A-0 840 277, displays may be required
`In one embodiment,
`to be described in greater detail
`to display data not only from several sources, but also from
`hereinafter, the above-mentioned stored data defining the
`several kinds of source and, as will be appreciated, this can
`environment may define a plurality of generally prismatic
`lead to crowding if each source is to inhabit a separate area
`bodies each having at least a planar face onto which a
`of the display. Whilst the user operation of selecting a single
`respective display panel is mapped and an adjacent surface
`display panel and zooming out suchthatit fills the majority
`onto which said overlying part is mapped. Such prismatic
`Gif not all) of the available display space can improve the
`bodies, which may for example be parallelepidel blocks or
`clarity, it is becoming more commonforusers to require to
`objects, may have two or more surfaces adjacent said planar
`have a number of panels or windows open to view at any
`face with each of said surfaces carrying ancillary data to the
`given time.
`contents of the display panel, for which arrangementthe user
`operable input means is preferably operable to direct said
`viewpoint to a user-selected one of said surfaces carrying
`ancillary data. To further facilitate the indexing of the data
`panels by the user, the ancillary data on respective surfaces
`of a prismatic body may be divided into a predetermined
`number of data categories, with the respective prismatic
`bodies being arranged such that at least some ofthe pris-
`matic body respective faces having a given category of
`ancillary data may be viewed simultaneously from a single
`viewpoint. In other words,
`the selection of a particular
`viewpoint may bring into view the “top” edges of all the
`blocks on which the authors of the respective works appear-
`ing on the display panels are identified, whilst a second
`viewpoint might showall the left-side edges of the blocks on
`whichthe titles of the respective works are identified.
`As a further user-settable feature, and by operation of the
`same or another user operable input means, the user may be
`enabled to vary the extent of translucency for an overlying
`portion.
`Also in accordance with the present invention there is
`provided a method for control of on-screen display of data
`from two or more independent sources of data for display,
`comprising:
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`SUMMARYOF THE INVENTION
`
`It is accordingly an object of the present invention to
`provide a display system which gives improved volume of
`display capacity per unit area of display surface.
`It is a further, subsidiary, object to provide such a system
`supporting improved indexing and access facilities for the
`user.
`
`In accordance with a first aspect of the present invention
`there is provided an on screen display generation apparatus
`comprising: two or more independent sources of data for
`display; a windows controller arranged to generate and
`periodically update a respective display panel for each
`source basedat least partially on data from that source; first
`storage means holding data for generated display panels
`including specification that at least a part of one panel is
`translucent; and a display controller configured to generate
`output pixel values for display based at least partially on
`contributions from two or more of said display panels, with
`certain pixels having contributions from two display panels
`wherea first panel is positioned to at least partially overlie
`a second and the overlying partof the first panel is specified
`as translucent.
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`US 6,661,426 B1
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`3
`generating and periodically updating a respective display
`panel for each source based at least partially on data
`from that source;
`storing the generated display panels together with speci-
`fication that at least a part of one panelis translucent;
`and
`
`generating output pixel values for display based at least
`partially on contributions from two or more of said
`display panels, with certain pixels having contributions
`from two display panels where a first panel is posi-
`tioned to at least partially overlie a second and the
`overlying part ofthe first panel is specified as translu-
`cent.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`Further features and advantages of the present invention
`will become apparent from reading of the following descrip-
`tion of preferred embodiments of the present
`invention,
`given by way of example only, and with reference to the
`accompanying drawings, in which:
`FIG. 1 is a block schematic diagram of apparatus embody-
`ing the present invention;
`FIG. 2 showsa first arrangement of display panels in an
`on-screen display;
`FIG. 3 shows a second arrangement of display panels in
`an on-screen display; and
`FIGS. 4 and 5 illustrate navigation of an indexing inter-
`face provided by a modified version ofthe first arrangement
`of FIG. 2.
`
`DETAILED DESCRIPTION OF THE
`PREFERRED EMBODIMENTS
`
`Beginning with FIG. 1, an on-screen display generation
`apparatus embodyingthe inventionis illustrated generally at
`10. Coupled to the apparatus are a number of independent
`sources of data for display:
`in the example shown,
`the
`sources comprise first 12 and second 14 television tuners, a
`web browser 16 and an electronic mail facility 18. The web
`browser 16 and e-mail facility 18 are coupled to access data
`over the Internet by a suitable interface 20.
`In the following, we are concerned principally with the
`handling of the image (and ancillary data) content received
`by the television tuners: the handling of audio signals is not
`an element of the present invention and has been omitted
`from the following examples for the sake of clarity.
`The apparatus 10 comprises a windows controller 22
`coupled to receive data from the sources 12, 14, 16, 18 and,
`under the direction of a central processing unit (CPU) 24
`co-ordinating operations of the apparatus, the controller 22
`is arranged to generate and periodically update a respective
`display panel for each source basedat least partially on data
`from that source: options for the particular form and format
`of display will be discussed hereinafter.
`Coupled with the windowscontroller 22 is a first storage
`means in the form of panel and translucency data (PTD)
`store 26 holding data for display panels generated by the
`controller 22 and including specification that at least a part
`of one or more of the panels is translucent. Where a
`predetermined level of translucency is specified for all
`overlapping panels or panel segments in the system,
`the
`specification of translucency held in store 26 maybeaslittle
`as a single flag per display panel indicating whetherornot,
`whenthat particular panel overlays another panel,it is to be
`rendered opaque or translucent. As will be described
`hereinafter, a more detailed specification for a panel may be
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`supported with store 26 holding specification of differing
`translucency levels for individual areas of a display panel,
`down to a resolution of a single pixel.
`Also coupled to the system CPU 24, and arranged to read
`the data panel colour and translucency data from store 26, a
`display controller 28 is configured to generate output pixel
`values for supply via a display buffer 30 to television or
`display screen 32: in the Figure, a display featuring two such
`display panels 34, 36 is shown. The display controller 28
`generates the pixel values basedat least partially on contri-
`butions from two or more of said display panels. Other
`contributions may come from a background or wallpaper 38
`which the display panels overlie.
`A further feature of the apparatus, coupled to the system
`CPU 24 via a suitable interface 40, is one or more user input
`devices 42 by meansof which the user is enabled to interact
`with the displayed data on screen 32. The particular form of
`the or each interface device 42 will be dependenton the level
`of interaction supported. For example, where the apparatus
`10 is housed in a set-top box supplying imagesto a televi-
`sion 32, the input device may be in the form of a hand-held
`remote control device for the television, controlling the
`television through commandssent over an infra-red link in
`known fashion. Where the apparatus 10 is housed in a home
`computer, the UID 42 may comprise a computer keyboard
`together with a pointer device for inputting movement
`commands in two or three dimensions.
`
`Turning now to FIG. 2, a first potential arrangement of
`display panels to form a user interface is illustrated. The
`arrangement comprises four panels 80-83 arranged to simu-
`late receding panels in parallel alignment, with one behind
`the other in a three-dimensional interface space 84. Note that
`the border 86 is not constrained to have the proportions
`shown, and may instead have an aspectratio of 4:3 or 16:9
`as determined by the display device.
`In order to generate the arrangementof FIG. 2, the display
`controller 28 of FIG. 1 is preferably arranged to generate a
`two dimensional image of the three dimensional interface
`space or environment 84, based on stored data defining the
`environmentheld in a further memory device 44 or further
`area of system memory coupled with the display controller.
`In conventional manner for the handling of three dimen-
`sional
`imaging for virtual
`reality and associated
`applications, the image is generated from a predetermined
`viewpoint having a given location and orientation within the
`environment. The display panels, whether carrying graphic
`imagedata, live television images (as for panels 80 and 81),
`Internet web pages (as for panel 82) or e-mail messages
`(panel 83) are mapped onto surfaces within said environ-
`ment.
`
`In the example of FIG. 2, the windows controller (22;
`FIG. 1) has generated each display panel asa first portion
`and a second,attached, portion with only oneofthe first and
`second portions being specified as translucent. As shown,
`each display panel 80-83 comprises a first portion a on
`which the displayed content appears and a second portion B
`attachedto the first and carrying ancillary data to identify the
`contents of each panel
`to the user. As shown,
`the first
`portions a of the respective display panels are opaque,
`whereas the second portions f are translucent, revealing at
`least partially the contents of the overlaidfirst portion a from
`the display panel behind.
`With the arrangement of display panels as shownin FIG.
`2, scrolling through the different sources is suitably achieved
`by moving the viewpoint within the environment 84 such
`that the user appears to “fly over” the panels, with the
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`6
`As for the FIG. 2 embodiment, the prismatic or parallel-
`epidel block onto which the display panel and ancillary
`panels are mapped is assumed to be transparent (it
`is
`effectively just a set of coordinates within the 3D environ-
`ment defining the box or panel outline) and each of the
`Turning now to FIG. 3, an alternative arrangement of
`ancillary panels 6 is also rendered at least partially trans-
`display panels is shown, withafirst (full screen) panel 90
`parent to enable some content from the display panel of the
`being overlaid by a smaller, partially translucent, windowed
`block behind to be seen—this is particularly useful where
`displayed panel 92. In terms of content, the full screen panel
`data on the rear surface of a block is being read, which data
`may be carrying a television broadcast, with the overlaid
`would otherwise largely obscure the display surface of the
`window comprising a web page. The web page may be
`following block.
`specifically associated with the television broadcast dis-
`From reading the present disclosure, other variations will
`played (indeed the broadcast data may identify the page
`be apparentto persons skilled in the art. Such variations may
`specifically and in a way detectable by the web browser
`involve other features which are already knownin thefield
`accessing the page) or it may be more generically linked,
`of apparatuses having graphical or screen display interfaces
`with the web browser having means foridentifying (at least
`or componentparts thereof and/or methodsfor control of the
`to a broad level of classification) the subject matter of the
`same and which maybe used instead of or in addition to
`broadcast and then acting as a search engineto find and call
`features already described herein.
`up a page of potentially interesting ancillary data for the
`Whatis claimedis:
`user.
`1. On screen display generation apparatus comprising:
`two or more independent sources of data for display;
`a windowscontroller arranged to generate and periodi-
`cally update a respective display panel for each source
`based at least partially on data from that source;
`first storage means holding data for generated display
`panels including specification that :at least a part of one
`panel is translucent; and
`display controller configured to generate output pixel
`values for display based at least partially on contribu-
`tions from two or more of said display panels, with
`FIGS. 4 and 5 illustrate a variant on the arrangement of
`certain pixels having contributions from two display
`FIG. 2 which makesparticular use of the display controller
`
`panels whereafirst panel is positioned to at least
`
`arrangement for generating a two dimensional image of a
`partially overlie a second and the overlying part of the
`three dimensional environment, based on stored data defin-
`first panel
`is specified as translucent, wherein the
`ing the environment, from a user-movable viewpoint within
`windowscontrolleris arranged to generate each display
`said environment, and with said display panels mapped onto
`panel as a first portion and a second, attached, portion
`surfaces within said environment.
`with only one of the first and second portions being
`specified as translucent and wherein oneof said sources
`comprises a source of video image frame sequences
`and the display panel for that source displays the video
`image framesin the portion other than that specified as
`translucent.
`
`The example of FIG. 3 shows how discrete areas of the
`overlaid display panel may be individually specified in terms
`oftransparency, with the picture and text indicated generally
`at 94 being opaque(i.e. fully obscuring the television picture
`beneath) whilst the picture and text indicated generally at 96
`is translucent and is not so intrusive to the viewer. In order
`the further clear the broadcast image for the viewer (for
`example whilst the web browseris searching for new pages),
`the windowed display panel 92 may be minimised to an icon
`at the bottom of the screen in known manner.
`
`the stored data defining the environment
`As before,
`defines a plurality of generally prismatic bodies 100, 101,
`102 each having at least a planar face @ onto which a
`respective display panel is mapped (the mapped data being
`omitted for the sake of clarity from FIGS. 4 and 5) and an
`adjacent surface § onto which said overlying part is mapped.
`The particular feature of this embodiment
`is that each
`prismatic body has two or more adjacent surfaces 6.1, 6.2
`from the planar face with each of these adjacent surfaces B
`carrying ancillary data to the contents of the display panel.
`By operation of the user input device (UID 42; FIG. 1), the
`user is enabled to direct the viewpoint (as indicated by arrow
`105) toward a user-selected one of the surfaces B.1, 6.2
`carrying ancillary data.
`The ancillary data on the respective surfaces 6.1 and 6.2
`of the prismatic body is divided into a predetermined
`number of data categories (A: Data; B: Data), with the
`respective prismatic bodies being arranged suchthatat least
`someof the prismatic body respective faces having a given
`category of ancillary data may be viewed simultaneously
`from a single viewpoint, i.e. such that all the “A: Data” faces
`line up (as in FIG. 4) or all the “B: Data” faces line up (as
`in FIG. 5).
`These different data categories enable a user to search or
`index through the panels by different categories of data. For
`example, where the main display panel a carries e-mail
`messages, the side panels (and even the back of the paral-
`lelepidel block) may be respectively assigned to carry data
`identifying the author, subject matter,
`time and/or date
`received and so forth.
`
`US 6,661,426 B1
`
`5
`content portions a of three or four of the panels visible
`simultaneously and thetitle bar or ancillary data portions B
`being translucent to reduce the extent to which they obscure
`the content of the window behind.
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`2. Apparatus as claimed in claim 1, wherein said one of
`said sources supplies ancillary data to said video image
`frame sequences and the windowscontroller is arranged to
`generate content in the portion specified as translucent on
`the basis of said ancillary data.
`3. Apparatus as claimed in claim 1, wherein one of said
`sources comprises a tuner capable of receiving broadcast
`television signals.
`4. Apparatus as claimed in claim 3, wherein another of
`said sources is a web browser configured to obtain from the
`Internet web pagesrelated to a currently displayed broadcast
`television signal and to present any web pages so found in
`an at leastpartially translucent panel overlying that panel on
`which images from the broadcast television signal are being
`shown.
`
`5. Apparatus as claimed in claim 3, wherein said display
`controller is arranged to generate a two dimensional image
`of a three dimensional environment, based on stored data
`defining said environment, from a predetermined viewpoint
`within said environment, and with said display panels
`mapped onto surfaces within said environment.
`6. Apparatus as claimed in claim 5, further comprising
`user-operable input means by operation of which the user is
`enabled to maneuver the location and/or direction of said
`viewpoint within the three dimensional environment.
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`US 6,661,426 B1
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`first storage means holding data for generated display
`7. Apparatus as claimed in claim 6, wherein the stored
`data defining the environmentdefines a plurality of gener-
`panels including specificationthat at least a part of one
`ally prismatic bodies each having at least a planar face onto
`panel is translucent;
`which a respective display panel is mapped and an adjacent
`a display controller configured to generate output pixel
`surface onto which said overlying part is mapped.
`values for display based at least partially on contribu-
`8. Apparatus as claimed in claim 7, wherein each pris-
`tions from two or more of said display panels, with
`matic body has two or more surfaces adjacent said planar
`certain pixels having contributions from two display
`face with each of said surfaces carrying ancillary data to the
`
`panels whereafirst panel is positioned to at least
`
`contents of the display panel, and the user operable input
`10
`meansis operable to direct said viewpoint to a user-selected
`partially overlie a second and the overlying part of the
`one of said surfaces carrying ancillary data.
`first panel
`is specified as translucent, wherein said
`9. Apparatus as claimed in claim 8, wherein the ancillary
`display controller is arranged to generate a two dimen-
`data on respective surfaces of a prismatic body is divided
`sional imageof a three dimensional environment, based
`into a predetermined number of data categories, with the
`on stored data defining said environment, from a pre-
`respective prismatic bodies being arranged suchthatat least
`determined viewpoint within said environment, and
`someof the prismatic body respective faces having a given
`with said display panels mapped onto surfaces within
`category of ancillary data may be viewed simultaneously
`said environment; and
`from a single viewpoint.
`10. Apparatus as claimed in claim 1, further comprising
`user operable input means by operation of which a user is
`enabled to vary the extent of translucency for an overlying
`portion.
`11. A methodfor control of on-screen display of data from
`two or more independent sources of data for display, com-
`prising:
`generating and periodically updating a respective display
`panel for each source based at least partially on data
`from that source;
`storing the generated display panels together with speci-
`fication that at least a part of one panelis translucent;
`and
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`user-operable input means by operation of which the user
`is enabled to maneuver the location and/or direction of
`said viewpoint within the three dimensional
`environment, wherein the stored data defining the envi-
`ronment defines a plurality of generally prismatic bod-
`ies each having at least a planar face onto which a
`respective display panel is mapped and an adjacent
`surface onto which said overlying part is mapped, and
`wherein each prismatic body has two or more surfaces
`adjacent said planar face with each of said surfaces
`carrying ancillary data to the contents of the display
`panel, and the user operable input meansis operable to
`direct said viewpoint to a user-selected one of said
`surfaces carrying ancillary data.
`13. Apparatus as claimed in claim 12, wherein the ancil-
`lary data on respective surfaces of a prismatic body is
`divided into a predetermined number of data categories,
`with the respective prismatic bodies being arranged such
`that at least some of the prismatic body respective faces
`having a given category of ancillary data may be viewed
`simultaneously from a single viewpoint.
`14. Apparatus as claimed in claim 12, further comprising
`user operable input means by operation of which a user is
`enabled to vary the extent of translucency for an overlying
`portion.
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`generating output pixel values for display based at least
`partially on contributions from two or more of said
`display panels, with certain pixels having contributions ,,
`from two display panels where a first panel is posi-
`tioned to at least partially overlie a second and the
`overlying part of the first panel
`is specified as
`translucent, wherein one of said sources comprises a
`source of video image frame sequencesand the display
`panelfor that source displays the video image frames in
`the portion other than that specified as translucent.
`12. On screen display generation apparatus comprising:
`two or more independent sources of data for display;
`a windowscontroller arranged to generate and periodi-
`cally update a respective display panel for each source
`based at least partially on data from that source;
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`9
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`