METHOD AND SYSTEM FOR NOTE TAKING

Abstract: A method and system for enabling handwritten note taking and retrieval, whereby a user is able to electronically capture, manage and search notes handwritten on paper by the user using one or more forms printed on paper and using a sensing device which senses coded data included in the printed forms.

Description: METHOD AND SYSTEM FOR NOTE TAKING FIELD OF INVENTION The present invention relates generally to handwritten note taking and, more particularly, to a method and system for enabling handwritten note taking and retrieval. CO-PENDING APPLICATIONS Various methods, systems and apparatus relating to the present invention are disclosed in the following co-pending applications filed by the applicant or assignee of the present invention simultaneously with the present application: PCT/AU00/00518, PCT/AU00/00519, PCT/AU00/00520, PCT/AU00/00521 , PCT/AU00/00522, PCT/AU00/00523, PCT/AU00/00524, PCT/AUOO/00525, PCT/AUOO/00526, PCT/AU00/00527, PCT/AU00/00528, PCT/AU00/00529, PCT/AU00/00530, PCT/AUOO/00531, PCT/AU00/00532, PCT/AU00/00534, PCT/AU00/00535. PCT/AU00/00536. PCT/AU00/00537, PCT/AU00/00538, PCT/AU00/00539, PCT/AU00/00540, PCT/AU00/00541. PCT/AU00/00542, PCT/AU00/00543, PCT/AU00/00544, PCT/AU00/00545, PCT/AU00/00547. PCT/AU00/00546, PCT/AU00/00554, PCT/AU00/00556, PCT/AUOO/00557, PCT/AU00/00558, PCT/AU00/00559, PCT/AU00/00560, PCT/AU00/00561. PCT/AU00/00562. PCT/AUOO/00563. PCT/AU00/00564, PCT/AU00/00565, PCT/AU00/00566, PCT/AUOO/00567, PCT/AU00/00568, PCT/AUOO/00569, PCT/AU00/00570, PCT/AU00/00571 , PCT/AUOO/00572, PCT/AU00/00573, PCT/AUOO/00574, PCT/AU00/00575, PCT/AU00/00576, PCT/AU00/00577, PCT/AU00/00578, PCT/AU00/00579, PCT/AU00/00581, PCT/AUOO/00580, PCT/AU00/00582, PCT/AU00/00587, PCT/AUOO/00588, PCT/AU00/00589, PCT/AU00/00583, PCT/AU00/00593, PCT/AU00/00590, PCT/AU00/00591 , PCT/AU00/00592, PCT/AU00/00594, PCT/AU00/00595, PCT/AU00/00596, PCT/AU00/00597, PCT/AU00/00598, PCT/AU00/00516, and PCT/AU00/00517 . The disclosures of these co-pending applications are incorporated herein by cross-reference. BACKGROUND Note taking is practised by an enormous number of individuals, in the personal, educational, and professional spheres. Individuals keep personal diaries to record events in their lives. Students take notes in classrooms and lecture halls which they later may amend and review in preparation for examination on that subject matter. Executive workers take notes in meetings to record action events and prepare to-do lists. Scientists write notes in laboratory notebooks to record experimental methods and results. Despite the availability of portable computers, the majority of people still use paper notebooks. The free- form input allowed by paper notebooks, along with their general versatility and simplicity, means that they remain a preferred option. However, the information contained in a paper notebook is of course not integrated with digital data and is therefore very inflexible to subsequently use. In particular, it is very difficult to find specific information in such notebooks, as they must be searched manually. Further, there is no means of automatically recording when an entry was made, known as 'timestamping' of an entry. Computer systems allowing the real-time capture, the storage and the retrieval of manuscript notes are already known. Such systems allow users to 'write' on a notepad computer, the computer capturing and recording the information and using character recognition algorithms if appropriate to convert the handwritten text to electronic text. If required, 1a each input stroke may be timestamped, in order to log that particular input and to aid retrieval However, such systems have not generally enjoyed widespread use, at least partly because note takers still prefer the simplicity and flexibility of paper notebooks The present invention has as its object to address the need for a more functional note taking method and system than hitherto provided by conventional paper notebooks, whilst avoiding the drawbacks inherent in the known or contemplated electronic notebook approaches SUMMARY OF INVENTION It is an objective of the present invention to provide a new system and method for enabling handwritten note taking and retrieval - 2 - the method mcludmg the steps of providmg a user with at least one form printable on a surface, the form containing mformation relatmg to a notebook activity and mcludmg coded data mdicative of an identity of the form and of at least one reference pomt of the form, receiving, m a computer system, mdicatmg data from a sensmg device operated by said user, said mdicatmg data regardmg the identity of the form and a position of the sensmg device relative to the form, the sensmg device, when placed in an operative position relative to the form, sensmg the mdicatmg data usmg at least some of the coded data, and identifymg m the computer system and from the mdicatmg data, at least one parameter relatmg to the notebook activity In a second aspect, the mvention provides a method of enablmg handwntten note takmg and retneval, the method mcludmg the steps of providmg a user with at least one form printable on a surface, said form containing mformation relatmg to a notebook activity and mcludmg coded data mdicative of at least one parameter of the notebook activity, receiving, m a computer system, data from a sensmg device operated by said user regardmg said at least one parameter and regardmg movement of the sensmg device relative to said form, the sensmg device, when moved relative to said form, sensmg the data regardmg said at least one parameter usmg at least some of the coded data and generating the data regardmg its own movement relative to said form, and interpreting, m the computer system, said movement of the sensmg device as it relates to said at least one parameter In a thud aspect, the mvention provides a method of enablmg handwritten note ta mg and retrieval, the method mcludmg the steps of providmg a notebook user with a form mcludmg coded data mdicative of an identity of said form, receiving, m a computer system, data from a sensmg device regardmg an identity of the user and regardmg the identity of said form, the sensmg device containing the data regardmg the identity of the user and sensmg the data regardmg the identity of said form usmg at least some of the coded data, and identifymg, m the computer system and from the data regardmg the identity of the user and the identity of the form, a notebook activity Accordmg to a fourth aspect of the mvention, there is provided a system for enablmg handwntten note taking and retneval, the system mcludmg at least one form printable on a surface, said form containing mformation relatmg to a notebook activity and mcludmg coded data mdicative of an identity of said form and of at least one reference pomt of said form, and a computer system for receiving mdicatmg data from a sensmg device operated by a user mvolved m the notebook activity, said mdicatmg data regardmg the identity of said form and a position of the sensmg device relative to said form, the sensmg device, when placed m an operative position relative to said form, sensmg the mdicatmg data usmg at least some of the coded data, said computer system mcludmg means for identifymg, from the mdicatmg data, at least one parameter relatmg to the notebook activity In a fifth aspect, the invention provides a system for enablmg handwntten note takmg and retneval, the system mcludmg at least one form printable on an mteractive surface, said form containing information relatmg to a notebook activity and mcludmg coded data mdicative of at least one parameter of the notebook activity, and a computer system for receivmg data from a sensmg device operated by the notebook user, said data regardmg movement of the sensmg device relative to said form, and for interpreting said movement of the sensmg device as it relates to said at least one parameter, the sensmg device, when moved relative to said form, sensmg the data regardmg said at least one parameter usmg at least some of the coded data, and generatmg e data regardmg its own movement relative to said form In a sixth aspect, the mvention provides a system for enablmg handwntten note takmg and retneval, the system mcludmg a form mcludmg coded data mdicative of an identity of the form, and a computer system for receivmg from a sensmg device data regardmg an identity of a notebook user and the identity of said form, and for identifymg, from said received data, a notebook activity, the sensmg device containing the data regardmg the identity of the user and sensmg the data regardmg the identity of the form usmg at least some of the coded data Accordmgly, the present mvention provides a system and a method which utilizes one or more forms capable of mteracting with a computer system Whilst the novel method and system of the present mvention may be used m conjunction with a smgle computer system, m a particularly preferred form it is designed to operate over a computer network, such as the Internet As a physical entity, the mteractive form is constructed as a surface medium and may be of any suitable structure However, m a preferred -urangement, the form compnses sheet matenal such as paper or the like which has the coded data pnnted on it and which allows it to mteract with the computer system The coded data is detectable preferably, but not exclusively, outside the visible spectrum, thereby enablmg it to be machine-readable but substantially invisible to the human eye The form may also mclude visible matenal which provides mformation to a user, such as the application or purpose of the form, and which visible information may be registered or correlate m position with the relevant hidden coded data The system also mcludes a sensmg device to convey data from the form to the computer system, and m some mstances, to contπbute additional data Agam, the sensmg device may take a vanety of forms but is preferably compact and easily portable In a particularly preferred aπangement, the sensmg device is configured as a pen which is designed to be able to physically mark the mteractive form as well as to selectively enable the coded data from the form to be read and transmitted to the computer system The coded data then provides control information, configured such that designation thereof by a user causes instructions to be applied to the software running on the computer system or network The nature of the mteraction between the form and the sensmg device and the data that each contnbutes to the computer system may vary In one arrangement, the coded data on the form is mdicative of the identity of the form and of at least one reference pomt on that form In another embodiment, the mteractive form mcludes coded data which is mdicative of a parameter of the form, whereas the sensmg device is operative to provide data regardmg its own movement relative to that form to the computer system together with coded data from the form In yet another arrangement, the form mcludes the coded data which at least identifies the form, and the sensmg device is designed to provide, to the computer system, data based on the form coded data, and also on data which identifies the user of the device In a preferred arrangement, the system and method also employs specially designed pπnters to pπnt the mteractive form Further these pnnters constitute or form part of the computer system and are designed to receive data from the sensmg device As mdicated above, the system and method of the mvention is ideally suited to operate over a network In this arrangement, the pπnters are fully mtegrated mto the network and allow for pnntmg of the mteractive forms on demand and also for distributing of the forms usmg a mixture of multi-cast and pomt-cast commumcation protocols Accordmgly, m a preferred form, the present mvention provides methods and svstems which use a paper and pen based mterface for a computer system This provides many significant benefits over traditional computer systems The advantage of paper is that it is widely used to display and record information Further, pπnted information is easier to read than information displayed on a computer screen Moreover, paper does not run on battenes, can be read m bnght light, or robustly accepts coffee spills or the like and is portable and disposable Furthermore, the system allows for hand-drawing and hand-wnting to be captured which affords greater nchness of expression than mput via a computer keyboard and mouse The present mvention therefore provides a system and method for enablmg handwntten note takmg and retneval making use of novel mteractive surface media The mteractive surface media provides the facility for handwntten note takmg m a novel form of notebook, which can be used to capture handwntten notes m a persistent manner The notes may be signed by a thud party to provide proof of recordal, for example with respect to a laboratory notebook requiring corroboration of experimental technique or results, which may at a later date be needed to establish pnonty date with respect to a patent application As the svstem of the mvention allows the mput to a notebook to be linked to a particular page mstance, a page can contain notes captured at different tunes Subsequently, if a notebook page is pnnted, it will contain a facsimile of all the notes on that page, whenever they may have been captured Additionally, a user can selectively retπeve information regardmg the timestamping of the different entnes on that page, or can retneve a version of the page as recorded at a particular moment m time (l e before later additions to that page were made) The handwnting can be recognized and converted to text for indexing purposes so that the notes can be searched by keyword The notebook also supports searching without text conversion, thus allowing the user to search on graphical information The notebooks or notebook pages may be pre-pnnted or pπnted on demand BRIEF DESCRIPTION OF DRAWINGS Preferred and other embodiments of the mvention will now be descπbed, by way of non-limiting example only, with reference to the accompanying drawings, m which Figure 1 is a schematic of a the relationship between a sample pπnted netpage and its onlme page descnption, Figure 2 is a schematic view of a mteraction between a netpage pen, a netpage pnnter, a netpage page server, and a netpage application server, Figure 3 illustrates a collection of netpage servers and pπnters interconnected via a network, Figure 4 is a schematic view of a high-level structure of a pnnted netpage and its onlme page descnption, Figure 5 is a plan view showmg a structure of a netpage tag, Figure 6 is a plan view showing a relationship between a set of the tags shown m Figure 5 and a field of view of a netpage sensmg device m the form of a netpage pen, Figure 7 is a flowchart of a tag image processmg and decoding algonthm, Figure 8 is a perspective view of a netpage pen and its associated tag-sensing field-of-view cone, Figure 9 is a perspective exploded view of the netpage pen shown m Figure 8, Figure 10 is a schematic block diagram of a pen controller for the netpage pen shown m Figures 8 and 9, Figure 11 is a perspective view of a wall-mounted netpage pπnter, Figure 12 is a section through the length of the netpage pnnter of Figure 11, Figure 12a is an enlarged portion of Figure 12 showmg a section of the duplexed pπnt engmes and glue wheel assembly, Figure 13 is a detailed view of the ink cartndge, ink, au and glue paths, and pnnt engmes of the netpage pnnter of Figures 11 and 12, - 5 - Figure 14 is a schematic block diagram of a pnnter controller for the netpage pπnter shown m Figures 11 and 12, Figure 15 is a schematic block diagram of duplexed pnnt engme controllers and Memjet™ prmtheads associated with the pnnter controller shown m Figure 14, Figure 16 is a schematic block diagram of the pnnt engme controller shown m Figures 14 and 15, Figure 17 is a perspective view of a smgle Memjet™ pnntmg element, as used m, for example, the netpage pnnter of Figures 10 to 12, Figure 18 is a perspective view of a small part of an array of Memjet™ pnntmg elements, Figure 19 is a senes of perspective views illustrating the operatmg cycle of the Memjet™ pnntmg element shown m Figure 13, Figure 20 is a perspective view of a short segment of a pagewidth Memjet™ pnnthead, Figure 21 is a schematic view of a user class diagram, Figure 22 is a schematic view of a pπnter class diagram, Figure 23 is a schematic view of a pen class diagram, Figure 24 is a schematic view of an application class diagram, Figure 25 is a schematic view of a document and page descπption class diagram, Figure 26 is a schematic view of a document and page ownership class diagram, Figure 27 is a schematic view of a terminal element specialization class diagram, Figure 28 is a schematic view of a static element specialization class diagram, Figure 29 is a schematic view of a hyperlink element class diagram, Figure 30 is a schematic view of a hyperlink element specialization class diagram, Figure 31 is a schematic view of a hyperimked group class diagram, Figure 32 is a schematic view of a form class diagram, Figure 33 is a schematic view of a digital ink class diagram, Figure 34 is a schematic view of a field element specialization class diagram, Figure 35 is a schematic view of a checkbox field class diagram, Figure 36 is a schematic view of a text field class diagram, Figure 37 is a schematic view of a signature field class diagram, Figure 38 is a flowchart of an mput processmg algonthm, Figure 38a is a detailed flowchart of one step of the flowchart of Figure 38, Figure 39 is a schematic view of a page server command element class diagram, Figure 40 is a schematic view of a resource descπption class diagram, Figure 41 is a schematic view of a favontes list class diagram, Figure 42 is a schematic view of a history list class diagram, Figure 43 is a schematic view of a subscnption delivery protocol, Figure 44 is a schematic view of a hyperlink request class diagram, Figure 45 is a schematic view of a hyperlink activation protocol, Figure 46 is a schematic view of a form submission protocol, Figure 47 is a schematic view of a commission payment protocol, Figure 48 is a schematic view of a set of user mterface flow document icons, Figure 49 is a schematic view of a set of user mterface page layout element icons, Figure 50 is a schematic view of a note takmg class diagram, Figure 51 is a schematic view of a user mterface flow for a notebook menu, Figure 52 is a schematic view of a user mterface flow for a notebook page, Figure 53 is a schematic view of a notebook menu page, Figure 54 is a schematic view of a new notebook page, Figure 55 is a schematic view of a notebook page, Figure 56 is a schematic view of a notebook search page, Figure 57 is a schematic view of a notebook list page, and Figure 58 is a schematic view of a search results page DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS Note Memjet™ is a trade mark of Silverbrook Research Pty Ltd, Australia In the preferred embodiment, the mvention is configured to work with the netpage networked computer system, a detailed overview of which follows It will be appreciated that not every implementation will necessaπly embody all or even most of the specific details and extensions discussed below m relation to the basic system However, the system is descnbed m its most complete form to reduce the need for external reference when attemptmg to understand the context m which the preferred embodiments and aspects of the present mvention operate In bnef summary, the preferred form of the netpage system employs a computer mterface in the form of a mapped surface, that is, a physical surface which contams references to a map of the surface mamtamed m a computer system The map references can be quened by an appropnate sensing device Depending upon the specific implementation, the map references mav be encoded visibly or invisibly, and defined m such a way that a local query on the mapped surface yields an unambiguous map reference both withm the map and among different maps The computer system can contam information about features on the mapped surface, and such information can be retneved based on map references supplied by a sensmg device used with the mapped surface The information thus retπeved can take the form of actions which are initiated by the computer system on behalf of the operator m response to the operator's mteraction with the surface features In its preferred form, the netpage system relies on the production of, and human mteraction with, netpages These are pages of text, graphics and images pπnted on ordinary paper, but which work like mteractive web pages Information is encoded on each page usmg ink which is substantially invisible to the unaided human eye The ink, however, and thereby the coded data, can be sensed by an optically imaging pen and transmitted to the netpage system In the preferred form, active buttons and hyperlinks on each page can be clicked with the pen to request uiformation from the network or to signal preferences to a network server In one embodiment, text wntten by hand on a netpage is automatically recognized and converted to computer text m the netpage system, allowmg forms to be filled m In other embodiments, signatures recorded on a netpage are automatically venfied, allowmg e-commerce transactions to be securely authoπzed As illustrated m Figure 1, a pπnted netpage 1 can represent a mteractive form which can be filled m by the user both physically, on the pπnted page, and "electronically", via commumcation between the pen and the netpage system The example shows a "Request" form containing name and address fields and a submit button The netpage consists of graphic data 2 pπnted usmg visible ink, and coded data 3 pπnted as a collection of tags 4 usmg invisible mk The correspondmg page descπption 5, stored on the netpage network, descnbes the mdividual elements of the netpage In particular it descnbes the type and spatial extent (zone) of each mteractive element (1 e text field or button m the example), to allow the netpage system to correctly mterpret mput via the netpage The submit button 6, for example, has a zone 7 which corresponds to the spatial extent of the correspondmg graphic 8 As illustrated m Figure 2, the netpage pen 101, a preferred form of which is shown m Figures 8 and 9 and descnbed m more detail below, works m conjunction with a netpage pnnter 601, an Internet-connected pnntmg - 7 - apphance for home, office or mobile use The pen is wireless and commumcates securely with the netpage pnnter via a short-range radio link 9 The netpage pnnter 601, a preferred form of which is shown m Figures 11 to 13 and descπbed m more detail below, is able to deliver, penodically or on demand, personalized newspapers, magazmes, catalogs, brochures and other publications, all pnnted at high quality as mteractive netpages Unlike a personal computer, the netpage pnnter is an appliance which can be, for example, wall-mounted adjacent to an area where the morning news is first consumed, such as m a user's kitchen, near a breakfast table, or near the household's pomt of departure for the day It also comes m tabletop, desktop, portable and miniature versions Netpages pπnted at theu pomt of consumption combme the ease-of-use of paper with the timeliness and interactivity of an mteractive medium As shown m Figure 2, the netpage pen 101 mteracts with the coded data on a pπnted netpage 1 and commumcates, via a short-range radio link 9, the mteraction to a netpage pπnter The pπnter 601 sends the mteraction to the relevant netpage page server 10 for mterpretation In appropnate cucumstances, the page server sends a corresponding message to application computer software ninning on a netpage application server 13 The application server may m turn send a response which is pπnted on the onginating pnnter The netpage system is made considerably more convement m the preferred embodiment by bemg used m conjunction with high-speed microelectromechanical system (MEMS) based inkjet (Memjet™) pπnters In the preferred form of this technology, relatively high-speed and high-quality pnntmg is made more affordable to consumers In its preferred form, a netpage publication has the physical characteristics of a traditional newsmagazme, such as a set of letter-size glossy pages pπnted in full color on both sides, bound together for easy navigation and comfortable handlmg The netpage pπnter exploits the growing availability of broadband Internet access Cable service is available to 95% of households m the Umted States, and cable modem service offeπng broadband Internet access is already available to 20% of these The netpage pnnter can also operate with slower connections, but with longer delivery tunes and lower image quality Indeed, the netpage system can be enabled usmg existing consumer inkjet and laser pπnters, although the system will operate more slowly and will therefore be less acceptable from a consumer's pomt of view In other embodiments, the netpage system is hosted on a pπvate intranet In still other embodiments, the netpage system is hosted on a smgle computer or computer-enabled device, such as a pπnter Netpage publication servers 14 on the netpage network are configured to deliver print-quality publications to netpage pnnters Penodical publications are delivered automatically to subscnbmg netpage pnnters via pointcasting and multicasting Internet protocols Personalized publications are filtered and formatted accordmg to individual user profiles A netpage pπnter can be configured to support any number of pens, and a pen can work with any number of netpage pπnters In the preferred implementation, each netpage pen has a umque identifier A household may have a collection of colored netpage pens, one assigned to each member of the family This allows each user to mamtam a distinct profile with respect to a netpage publication server or application server A netpage pen can also be registered with a netpage registration server 11 and linked to one or more payment card accounts This allows e-commerce payments to be securely authorized usmg the netpage pen The netpage registration server compares the signature captured by the netpage pen with a previously registered signature, allowmg it to authenticate the user's identity to an e-commerce server Other biometncs can also be used to venfy identity A version of the netpage pen mcludes fmgerpnnt scanning, venfied m a similar way by the netpage registration server Although a netpage pnnter may deliver penodicals such as the morning newspaper without user intervention, it can be configured never to deliver unsolicited unk mail In its preferred form, it only delivers periodicals - 8 - from subscnbed or otherwise authorized sources In this respect, the netpage pnnter is unlike a fax machine or e-mail account which is visible to any junk mailer who knows the telephone number or email address 1 NETPAGE SYSTEM ARCHITECTURE Each object model m the system is descnbed usmg a Unified Modelmg Language (UML) class diagram A class diagram consists of a set of object classes connected by relationships, and two lands of relationships are of mterest here associations and generalizations An association represents some land of relationship between objects, 1 e between mstances of classes A generalization relates actual classes, and can be understood m the followmg way if a class is thought of as the set of all objects of that class, and class A is a generalization of class B, then B is simply a subset of A The UML does not duectly support second-order modelling - I e classes of classes Each class is drawn as a rectangle labelled with the name of the class It contams a list of the attributes of the class, separated from the name by a honzontal lme, and a list of the operations of the class, separated from the attnbute list by a honzontal lme In the class diagrams which follow, however, operations are never modelled An association is drawn as a lme joining two classes, optionally labelled at either end with the multiplicity of the association The default multiplicity is one An astensk (*) mdicates a multiplicity of "many", I e zero or more Each association is optionally labelled with its name, and is also optionally labelled at either end with the role of the corresponding class An open diamond mdicates an aggregation association ('is-part-of'), and is drawn at the aggregator end of the association lme A generalization relationship ("ιs-a") is drawn as a solid lme joining two classes, with an arrow (m the form of an open tnangle) at the generalization end When a class diagram is broken up mto multiple diagrams, any class which is duplicated is shown with a dashed outline m all but the mam diagram which defines it It is shown with attnbutes only where it is defined 1.1 NETPAGES Netpages are the foundation on which a netpage network is built They provide a paper-based user mterface to published mformation and mteractive services A netpage consists of a pπnted page (or other surface region) invisibly tagged with references to an onlme descnption of the page The onlme page descnption is mamtamed persistently by a netpage page server The page descnption descnbes the visible layout and content of the page, mcludmg text, graphics and images It also descnbes the mput elements on the page, mcludmg buttons, hyperlinks, and mput fields A netpage allows markings made with a netpage pen on its surface to be simultaneously captured and processed by the netpage system Multiple netpages can share the same page descnption However, to allow mput through otherwise identical pages to be distinguished, each netpage is assigned a umque page identifier This page ID has sufficient precision to distinguish between a very large number of netpages Each reference to the page descnption is encoded m a pπnted tag The tag identifies the umque page on which it appears, and thereby mduectly identifies the page descπption The tag also identifies its own position on the page Charactenstics of the tags are descnbed m more detail below Tags are pπnted m infrared-absorptive ink on any substrate which is infrared-reflective, such as ordinary paper Near-infrared wavelengths are invisible to the human eye but are easily sensed by a solid-state image sensor with an appropnate filter A tag is sensed by an area image sensor m the netpage pen, and the tag data is fransmitted to the netpage system via the nearest netpage pπnter The pen is wueless and commumcates with the netpage pnnter via a short-range radio link Tags are sufficiently small and densely arranged that the pen can reliably image at least one tag even on a smgle click on the page It is important that the pen recognize the page ID and position on every mteraction with the page, smce the mteraction is stateless Tags are error-correctably encoded to make them partially tolerant to surface - 9 - damage The netpage page server mamtams a umque page mstance for each pπnted netpage, allowmg it to mamtam a distinct set of user-supplied values for mput fields m the page descπption for each pnnted netpage The relationship between the page descnption, the page mstance, and the pnnted netpage is shown m Figure 4 The page mstance is associated with both the netpage pnnter which pπnted it and, if known, the netpage user who requested it 1.2 NETPAGE TAGS 1.2.1 Tag Data Content In a preferred form, each tag identifies the region m which it appears, and the location of that tag within the region A tag may also contam flags which relate to the region as a whole or to the tag One or more flag bits may, for example, signal a tag sensing device to provide feedback mdicative of a function associated with the immediate area of the tag, without the sensmg device havmg to refer to a descnption of the region A netpage pen may, for example, illuminate an "active area" LED when m the zone of a hyperlink As will be more clearly explained below, m a preferred embodiment, each tag contams an easily recognized mvanant structure which aids initial detection, and which assists m minimizing the effect of any warp mduced by the surface or by the sensmg process The tags preferably tile the entue page, and are sufficiently small and densely arranged that the pen can reliably image at least one tag even on a smgle click on the page It is important that the pen recognize the page ID and position on every mteraction with the page, smce the mteraction is stateless In a preferred embodiment, the region to which a tag refers comcides with an entue page, and the region ID encoded m the tag is therefore synonymous with the page ID of the page on which the tag appears In other embodiments, the region to which a tag refers can be an arbitrary subregion of a page or other surface For example, it can comcide with the zone of an mteractive element, m which case the region ID can duectly identify the mteractive element Table 1 - Tag data Each tag contams 120 bits of information, typically allocated as shown m Table 1 Assummg a maximum tag density of 64 per square mch, a 16-bit tag ID supports a region size of up to 1024 square mches Larger regions can be mapped continuously without mcreasmg the tag ID precision simply by usmg abutting regions and maps The 100-bit region ID allows 2 100 (~10 , ° or a million tπlhon tnlhon) different regions to be umquely identified 1.2.2 Tag Data Encoding The 120 bits of tag data are redundantly encoded usmg a (15, 5) Reed-Solomon code This yields 360 encoded bits consisting of 6 codewords of 15 4-bit symbols each The (15, 5) code allows up to 5 symbol errors to be corrected per codeword, l e it is tolerant of a symbol error rate of up to 33% per codeword Each 4-bit symbol is represented m a spatially coherent way m the tag, and the symbols of the six codewords are mterleaved spatially withm the tag This ensures that a burst error (an error affecting multiple spatially adjacent bits) damages a muumum number of symbols overall and a minimum number of symbols m any one codeword, thus maximising the likelihood that the burst error can be fully corrected 1.2.3 Physical Tag Structure The physical representation of the tag, shown m Figure 5, mcludes fixed target structures 15, 16, 17 and vanable data areas 18 The fixed target structures allow a sensmg device such as the netpage pen to detect the tag and - 10 - lnfer its three-dimensional oπentation relative to the sensor The data areas contam representations of the individual bits of the encoded tag data To achieve proper tag reproduction, the tag is rendered at a resolution of 256x256 dots When pnnted at 1600 dots per mch this yields a tag with a diameter of about 4 mm At this resolution the tag is designed to be surrounded by a "quiet area" of radius 16 dots Smce the quiet area is also contnbuted by adjacent tags, it only adds 16 dots to the effective diameter of the tag The tag mcludes six target structures A detection nng 15 allows the sensmg device to initially detect the tag The nng is easy to detect because it is rotationally mvanant and because a sunple correction of its aspect ratio removes most of the effects of perspective distortion An onentation axis 16 allows the sensmg device to determme the approximate planar onentation of the tag due to the yaw of the sensor The oπentation axis is skewed to yield a umque onentation Four perspective targets 17 allow the sensmg device to infer an accurate two-dimensional perspective transform of the tag and hence an accurate three-dimensional position and oπentation of the tag relative to the sensor All target structures are redundantly large to improve theu immunity to noise The overall tag shape is cucular This supports, amongst other things, optimal tag packing on an irregular tnangular gπd In combmation with the cucular detection πng, this makes a cucular arrangement of data bits withm the tag optimal To maximise its size, each data bit is represented by a radial wedge m the form of an area bounded by two radial lmes and two concentnc cucular arcs Each wedge has a muumum dimension of 8 dots at 1600 dpi and is designed so that its base (its inner arc), is at least equal to this muumum dimension The height of the wedge m the radial duection is always equal to the muumum dimension Each 4-bit data symbol is represented by an array of 2x2 wedges The 15 4-bit data symbols of each of the six codewords are allocated to the four concentnc symbol rings 18a to 18d in mterleaved fashion Symbols are allocated alternately m circular progression around the tag The interleaving is designed to maximise the average spatial distance between any two symbols of the same codeword In order to support "single-click" mteraction with a tagged region via a sensmg device, the sensmg device must be able to see at least one entue tag m its field of view no matter where m the region or at what onentation it is positioned The reqmred diameter of the field of view of the sensmg device is therefore a function of the size and spacing of the tags Assummg a cucular tag shape, the πununum diameter of the sensor field of view is obtained when the tags are tiled on a equilateral tnangular gnd, as shown m Figure 6 1.2.5 Tag Image Processing and Decoding The tag image processmg and decodmg performed by a sensmg device such as the netpage pen is shown m Figure 7 While a captured unage is bemg acquired from the unage sensor, the dynamic range of the image is determined (at 20) The center of the range is then chosen as the binary threshold for the image 21 The unage is then thresholded and segmented mto connected pixel regions (l e shapes 23) (at 22) Shapes which are too small to represent tag target structures are discarded The size and centroid of each shape is also computed Binary shape moments 25 are then computed (at 24) for each shape, and these provide the basis for subsequently locating target structures Central shape moments are by theu nature mvanant of position, and can be easily made mvanant of scale, aspect ratio and rotation The nng target structure 15 is the first to be located (at 26) A πng has the advantage of bemg very well behaved when perspective-distorted Matching proceeds by aspect-normalizing and rotation-normalizmg each shape's moments Once its second-order moments are normalized the πng is easy to recognize even if the perspective distortion - 11 - was significant The πng's ongmal aspect and rotation 27 together provide a useful approximation of the perspective transform The axis target structure 16 is the next to be located (at 28) Matching proceeds by applymg the nng's normalizations to each shape's moments, and rotation-normalizmg the resulting moments Once its second-order moments are normalized the axis target is easily recognized Note that one thud order moment is req red to disambiguate the two possible oπentations of the axis The shape is deliberately skewed to one side to make this possible Note also that it is only possible to rotation-normalize the axis target after it has had the πng's normalizations applied, smce the perspective distortion can hide the axis target's axis The axis target's ongmal rotation provides a useful approximation of the tag's rotation due to pen yaw 29 The four perspective target structures 17 are the last to be located (at 30) Good estimates of theu positions are computed based on theu known spatial relationships to the πng and axis targets, the aspect and rotation of the πng, and the rotation of the axis Matching proceeds by applymg the πng's normalizations to each shape's moments Once their second-order moments are normalized the cucular perspective targets are easy to recognize, and the target closest to each estimated position is taken as a match The ongmal centroids of the four perspective targets are then taken to be the perspective-distorted corners 31 of a square of known size m tag space, and an eight-degree-of-freedom perspective transform 33 is inferred (at 32) based on solvmg the well-understood equations relatmg the four tag-space and image- space pomt pans The inferred tag-space to image-space perspective transform is used to project (at 36) each known data bit position m tag space mto image space where the real-valued position is used to bilinearly interpolate (at 36) the four relevant adjacent pixels m the mput unage The previously computed unage threshold 21 is used to threshold the result to produce the final bit value 37 Once all 360 data bits 37 have been obtained m this way, each of the six 60-bit Reed-Solomon codewords is decoded (at 38) to yield 20 decoded bits 39, or 120 decoded bits m total Note that the codeword symbols are sampled m codeword order, so that codewords are implicitly de-interleaved dunng the sampling process The πng target 15 is only sought m a subarea of the image whose relationship to the unage guarantees that the nng, if found, is part of a complete tag If a complete tag is not found and successfully decoded, then no pen position is recorded for the current frame Given adequate processmg power and ideally a non-muumal field of view 193, an alternative strategy mvolves seeking another tag m the current unage The obtained tag data mdicates the identity of the region containing the tag and the position of the tag within the region An accurate position 35 of the pen mb m the region, as well as the overall onentation 35 of the pen, is then inferred (at 34) from the perspective transform 33 observed on the tag and the known spatial relationship between the pen's physical axis and the pen's optical axis 1.2.6 Tag Map Decoding a tag results m a region ID, a tag ID, and a tag-relative pen transform Before the tag ID and the tag-relative pen location can be translated mto an absolute location within the tagged region, the location of the tag withm the region must be known This is given by a tag map, a function which maps each tag ID m a tagged region to a correspondmg location The tag map class diagram is shown m Figure 22, as part of the netpage pnnter class diagram A tag map reflects the scheme used to tile the surface region with tags, and this can vary according to surface type When multiple tagged regions share the same tiling scheme and the same tag numbering scheme, they can also share the same tag map The tag map for a region must be retnevable via the region ID Thus, given a region ID, a tag ID and a pen transform, the tag map can be retneved, the tag ID can be translated mto an absolute tag location withm the region, and - 12 - the tag-relative pen location can be added to the tag location to yield an absolute pen location within the region 1.2.7 Tagging Schemes Two distinct surface coding schemes are of mterest, both of which use the tag structure descnbed earlier m this section The preferred coding scheme uses "location-indicating" tags as already discussed An alternative coding scheme uses object-indicating tags A location-indicating tag contams a tag ID which, when translated through the tag map associated with the tagged region, yields a umque tag location within the region The tag-relative location of the pen is added to this tag location to yield the location of the pen within the region This m turn is used to determme the location of the pen relative to a user mterface element m the page descnption associated with the region Not only is the user mterface element itself identified, but a location relative to the user mterface element is identified Location-indicating tags therefore tnvially support the capture of an absolute pen path m the zone of a particular user mterface element An object-indicating tag contams a tag ID which duectly identifies a user mterface element m the page descnption associated with the region All the tags m the zone of the user mterface element identify the user mterface element, making them all identical and therefore indistinguishable Object-indicating tags do not, therefore, support the capture of an absolute pen path They do, however, support the capture of a relative pen path So long as the position sampling frequency exceeds twice the encountered tag frequency, the displacement from one sampled pen position to the next within a stroke can be unambiguously determined 1.3 DOCUMENT AND PAGE DESCRIPTIONS A preferred embodiment of a document and page descπption class diagram is shown m Figures 25 and 26 In the netpage system a document is descnbed at three levels At the most abstract level the document 836 has a hierarchical structure whose terminal elements 839 are associated with content objects 840 such as text objects, text style objects, image objects, etc Once the document is pnnted on a pnnter with a particular page size and accordmg to a particular user's scale factor preference, the document is paginated and otherwise formatted Formatted termmal elements 835 will m some cases be associated with content objects which are different from those associated with theu correspondmg terminal elements, particularly where the content objects are style-related Each pπnted mstance of a document and page is also descπbed separately, to allow mput captured through a particular page mstance 830 to be recorded separately from mput captured through other mstances of the same page descnption The presence of the most abstract document descnption on the page server allows a user to request a copy of a document without bemg forced to accept the source document's specific format The user may be requestmg a copy through a pnnter with a different page size, for example Conversely, the presence of the formatted document descnption on the page server allows the page server to efficiently mterpret user actions on a particular pnnted page A formatted document 834 consists of a set of formatted page descnptions 5, each of which consists of a set of formatted terminal elements 835 Each formatted element has a spatial extent or zone 58 on the page This defines the active area of mput elements such as hyperlinks and mput fields A document mstance 831 corresponds to a formatted document 834 It consists of a set of page mstances 830, each of which corresponds to a page descnption 5 of the formatted document Each page mstance 830 descnbes a smgle umque pnnted netpage 1, and records the page ID 50 of the netpage A page mstance is not part of a document mstance if it represents a copy of a page requested m isolation A page mstance consists of a set of termmal element mstances 832 An element mstance only exists if it records instance-specific information Thus, a hyperlmk mstance exists for a hyperlink element because it records a transaction ID 55 which is specific to the page mstance, and a field mstance exists for a field element because it records mput specific to the page mstance An element mstance does not exist, however, for static elements such as textflows A terminal element can be a static element 843, a hyperlmk element 844, a field element 845 or a page - 13 - server command element 846, as shown m Figure 27 A static element 843 can be a style element 847 with an associated style object 854, a textflow element 848 with an associated styled text object 855, an unage element 849 with an associated image element 856, a graphic element 850 with an associated graphic object 857, a video clip element 851 with an associated video clip object 858, an audio clip element 852 with an associated audio clip object 859, or a scnpt element 853 with an associated scnpt object 860, as shown m Figure 28 A page mstance has a background field 833 which is used to record any digital ink captured on the page which does not apply to a specific mput element In the prefeπed form of the mvention, a tag map 811 is associated with each page mstance to allow tags on the page to be translated mto locations on the page 1.4 THE NETPAGE NETWORK In a preferred embodiment, a netpage network consists of a distributed set of netpage page servers 10, netpage registration servers 11, netpage ID servers 12, netpage application servers 13, netpage publication servers 14, and netpage pnnters 601 connected via a network 19 such as the Internet, as shown m Figure 3 The netpage registration server 11 is a server which records relationships between users, pens, pπnters, applications and publications, and thereby authorizes vanous network activities It authenticates users and acts as a sigmng proxy on behalf of authenticated users m application transactions It also provides handwriting recogmtion services As descnbed above, a netpage page server 10 mamtams persistent uiformation about page descnptions and page mstances The netpage network mcludes any number of page servers, each handlmg a subset of page instances Smce a page server also mamtams user mput values for each page mstance, clients such as netpage pπnters send netpage mput duectly to the appropnate page server The page server mterprets any such mput relative to the descnption of the corresponding page A netpage ID server 12 allocates document IDs 51 on demand, and provides load-balancing of page servers via its ID allocation scheme A netpage pnnter uses the Internet Distnbuted Name System (DNS), or similar, to resolve a netpage page ID 50 mto the network address of the netpage page server handlmg the correspondmg page mstance A netpage application server 13 is a server which hosts mteractive netpage applications A netpage publication server 14 is an application server which publishes netpage documents to netpage pnnters They are descnbed m detail in Section 2 Netpage servers can be hosted on a vanety of network server platforms from manufacturers such as IBM, Hewlett-Packard, and Sun Multiple netpage servers can run concurrently on a smgle host, and a smgle server can be distnbuted over a number of hosts Some or all of the functionality provided by netpage servers, and m particular the functionality provided by the ID server and the page server, can also be provided directly m a netpage appliance such as a netpage pnnter, m a computer workstation, or on a local network 1.5 THE NETPAGE PRINTER The netpage prmter 601 is an appliance which is registered with the netpage system and prints netpage documents on demand and via subscnption Each pπnter has a umque pnnter ID 62, and is connected to the netpage network via a network such as the Internet, ideally via a broadband connection Apart from identity and secunty settings m non-volatile memory, the netpage pnnter contams no persistent storage As far as a user is concerned, "the network is the computer" Netpages function interactively across space and tune with the help of the distnbuted netpage page servers 10, mdependently of particular netpage pπnters The netpage pπnter receives subscnbed netpage documents from netpage publication servers 14 Each document is distnbuted m two parts the page layouts, and the actual text and image objects which populate the pages Because of personalization, page layouts are typically specific to a particular subscnber and so are pomtcast to the - 14 - subscnber's pnnter via the appropnate page server Text and unage objects, on the other hand, are typically shared with other subscnbers, and so are multicast to all subscnbers' pnnters and the appropnate page servers The netpage publication server optimizes the segmentation of document content mto pomtcasts and multicasts After receivmg the pomtcast of a document's page layouts, the pπnter knows which multicasts, if any, to listen to Once the pπnter has received the complete page layouts and objects that define the document to be pnnted, it can pnnt the document The pπnter rastenzes and pπnts odd and even pages simultaneously on both sides of the sheet It contams duplexed pπnt engme controllers 760 and pnnt engmes utilizing Memjet™ prmtheads 350 for this purpose The pnntmg process consists of two decoupled stages rasterization of page descnptions, and expansion and pnntmg of page unages The raster unage processor (RIP) consists of one or more standard DSPs 757 running m parallel The duplexed pnnt engme controllers consist of custom processors which expand, dither and pnnt page unages m real tune, synchronized with the operation of the prmtheads m the pπnt engmes Pπnters not enabled for IR pnntmg have the option to pnnt tags usmg IR-absorptive black ink, although this restncts tags to otherwise empty areas of the page Although such pages have more limited functionality than IR-pπnted pages, they are still classed as netpages A normal netpage pπnter pnnts netpages on sheets of paper More specialised netpage pnnters may pπnt onto more specialised surfaces, such as globes Each pπnter supports at least one surface type, and supports at least one tag tiling scheme, and hence tag map, for each surface type The tag map 811 which descnbes the tag tiling scheme actually used to pnnt a document becomes associated with that document so that the document's tags can be correctly interpreted Figure 2 shows the netpage pnnter class diagram, reflecting printer-related uiformation mamtamed by a registration server 11 on the netpage network A preferred embodiment of the netpage pπnter is descπbed m greater detail m Section 6 below, with reference to Figures 11 to 16 1.5.1 Memjet™ Prmtheads The netpage system can operate usmg pπnters made with a wide range of digital pnntmg technologies, mcludmg thermal inkjet, piezoelectric inkjet, laser electrophotographic, and others However, for wide consumer acceptance, it is desuable that a netpage pnnter have the followmg charactenstics • photographic quality color pnntmg • high quality text pnntmg • high reliability • low pπnter cost • low paper cost • sunple operation • nearly silent pnntmg • high pnntmg speed • simultaneous double sided pnntmg • compact form factor • low power consumption No commercially available pnntmg technology has all of these charactenstics - 15 - To enable to production of pnnters with these charactenstics, the present applicant has invented a new pnnt technology, referred to as Memjet™ technology Memjet™ is a drop-on-demand inkjet technology that incorporates pagewidth pπntheads fabncated usmg microelectromechamcal systems (MEMS) technology Figure 17 shows a smgle pnntmg element 300 of a Memjet™ pnnthead The netpage wallpnnter mcorporates 168960 pnntmg elements 300 to form a 1600 dpi pagewidth duplex pπnter This pπnter simultaneously pπnts cyan, magenta, yellow, black, and infrared inks as well as paper conditioner and ink fixative The pnntmg element 300 is approximately 110 microns long by 32 microns wide Arrays of these pnntmg elements are formed on a silicon substrate 301 that mcorporates CMOS logic, data transfer, timing, and dnve cucuits (not shown) Major elements of the pnntmg element 300 are the nozzle 302, the nozzle run 303, the nozzle chamber 304, the fluidic seal 305, the ink channel nm 306, the lever arm 307, the active actuator beam pau 308, the passive actuator beam pau 309, the active actuator anchor 310, the passive actuator anchor 311, and the ink inlet 312 The active actuator beam pau 308 is mechanically jomed to the passive actuator beam pau 309 at the jom 319 Both beams pans are anchored at theu respective anchor pomts 310 and 311 The combination of elements 308, 309, 310, 311, and 319 form a cantilevered electrothermal bend actuator 320 Figure 18 shows a small part of an array of pnntmg elements 300, mcludmg a cross section 315 of a pnntmg element 300 The cross section 315 is shown without mk, to clearly show the ink inlet 312 that passes through the silicon wafer 301 Figures 19(a), 19(b) and 19(c) show the operatmg cycle of a Memjet™ pnntmg element 300 Figure 19(a) shows the quiescent position of the ink memscus 316 pπor to pnntmg an ink droplet Ink is retained m the nozzle chamber by surface tension at the ink memscus 316 and at the fluidic seal 305 formed between the nozzle chamber 304 and the ink channel run 306 While pnntmg, the pnnthead CMOS cncuitry distnbutes data from the pnnt engme controller to the correct pnntmg element, latches the data, and buffers the data to dnve the electrodes 318 of the active actuator beam pau 308 This causes an electncal current to pass through the beam pau 308 for about one microsecond, resultmg m Joule heating The temperature mcrease resultmg from Joule heating causes the beam pan 308 to expand As the passive actuator beam pau 309 is not heated, it does not expand, resultmg m a stress difference between the two beam p-urs This stress difference is partially resolved by the cantilevered end of the electrothermal bend actuator 320 bending towards the substrate 301 The lever arm 307 transmits this movement to the nozzle chamber 304 The nozzle chamber 304 moves about two microns to the position shown m Figure 19(b) This mcreases the ink pressure, forcmg ink 321 out of the nozzle 302, and causmg the ink memscus 316 to bulge The nozzle run 303 prevents the ink memscus 316 from spreading across the surface of the nozzle chamber 304 As the temperature of the beam pans 308 and 309 equalizes, the actuator 320 returns to its oπgmal position This aids m the break-off of the ink droplet 317 from the ink 321 m the nozzle chamber, as shown m Figure 19(c) The nozzle chamber is refilled by the action of the surface tension at the meniscus 316 Figure 20 shows a segment of a pnnthead 350 In a netpage pπnter, the length of the pnnthead is the full width of the paper (typically 210 mm) m the direction 351 The segment shown is 04 mm long (about 02% of a complete pnnthead) When pnntmg, the paper is moved past the fixed pnnthead m the direction 352 The pnnthead has 6 rows of mterdigitated pnntmg elements 300, pnntmg the six colors or types of ink supplied by the ink inlets 312 To protect the fragile surface of the pnnthead dunng operation, a nozzle guard wafer 330 is attached to the pnnthead substrate 301 For each nozzle 302 there is a correspondmg nozzle guard hole 331 through which the mk droplets are fired To prevent the nozzle guard holes 331 from beconung blocked by paper fibers or other debns, filtered - 16 - au is pumped through the au inlets 332 and out of the nozzle guard holes dunng pnntmg To prevent ink 321 from drying, the nozzle guard is sealed while the pnnter is idle 1.6 The Netpage Pen The active sensmg device of the netpage system is typically a pen 101, which, usmg its embedded controller 134, is able to capture and decode JR. position tags from a page via an unage sensor The unage sensor is a solid-state device provided with an appropnate filter to permit sensmg at only near-infrared wavelengths As descπbed m more detail below, the system is able to sense when the mb is m contact with the surface, and the pen is able to sense tags at a sufficient rate to capture human handwnting (I e at 200 dpi or greater and 100 Hz or faster) Information captured by the pen is encrypted and wnelessly transmitted to the pπnter (or base station), the pπnter or base station interpreting the data with respect to the (known) page structure The prefeπed embodiment of the netpage pen operates both as a normal markmg ink pen and as a non- marking stylus The markmg aspect, however, is not necessary for usmg the netpage system as a browsmg system, such as when it is used as an Internet mterface Each netpage pen is registered with the netpage system and has a umque pen ID 61 Figure 23 shows the netpage pen class diagram, reflecting pen-related mformation mamtamed by a registration server 11 on the netpage network When either mb is m contact with a netpage, the pen determines its position and onentation relative to the page The mb is attached to a force sensor, and the force on the mb is interpreted relative to a threshold to mdicate whether the pen is "up" or "down" This allows a mteractive element on the page to be 'clicked' by pressmg with the pen mb, in order to request, say, mformation from a network Furthermore, the force is captured as a continuous value to allow, say, the full dynamics of a signature to be venfied The pen determines the position and onentation of its mb on the netpage by imaging, m the infrared spectrum, an area 193 of the page m the vicinity of the mb It decodes the nearest tag and computes the position of the nib relative to the tag from the observed perspective distortion on the imaged tag and the known geometry of the pen optics Although the position resolution of the tag may be low, because the tag density on the page is mversely proportional to the tag size, the adjusted position resolution is quite high, exceedmg the muumum resolution reqmred for accurate handwπtmg recogmtion Pen actions relative to a netpage are captured as a seπes of strokes A stroke consists of a sequence of tune- stamped pen positions on the page, initiated by a pen-down event and completed by the subsequent pen-up event A stroke is also tagged with the page ID 50 of the netpage whenever the page ED changes, which, under normal cucumstances, is at the commencement of the stroke Each netpage pen has a current selection 826 associated with it, allowmg the user to perform copy and paste operations etc The selection is timestamped to allow the system to discard it after a defined tune peπod The current selection descnbes a region of a page mstance It consists of the most recent digital ink stroke captured through the pen relative to the background area of the page It is interpreted m an application-specific manner once it is submitted to an application via a selection hyperlink activation Each pen has a current mb 824 This is the mb last notified by the pen to the system In the case of the default netpage pen descπbed above, either the markmg black ink mb or the non-marking stylus mb is current Each pen also has a current mb style 825 This is the mb style last associated with the pen by an application, e g m response to the user selecting a color from a palette The default mb style is the b style associated with the current mb Strokes captured through a pen are tagged with the current mb style When the strokes are subsequently reproduced, they are reproduced m the mb style with which they are tagged Whenever the pen is withm range of a pnnter with which it can commumcate, the pen slowly flashes its - 17 - "onlme" LED When the pen fails to decode a stroke relative to the page, it momentanly activates its "error" LED When the pen succeeds m decodmg a stroke relative to the page, it momentanly activates its "ok" LED A sequence of captured strokes is referred to as digital ink Digital ink forms the basis for the digital exchange of drawings and handwnting, for onlme recogmtion of handwπtmg, and for onlme venfication of signatures The pen is wireless and transmits digital ink to the netpage pπnter via a short-range radio link The transmitted digital ink is encrypted for pnvacy and secunty and packetized for efficient transmission, but is always flushed on a pen-up event to ensure timely handlmg m the pnnter When the pen is out-of-range of a pnnter it buffers digital ink m internal memory, which has a capacity of over ten mmutes of continuous handwntmg When the pen is once agam withm range of a pπnter, it transfers any buffered digital ink A pen can be registered with any number of pπnters, but because all state data resides m netpages both on paper and on the network, it is largely lmmatenal which pπnter a pen is communicating with at any particular tune A preferred embodiment of the pen is descπbed m greater detail in Section 6 below, with reference to Figures 8 to 10 1.7 NETPAGE INTERACTION The netpage pπnter 601 receives data relatmg to a stroke from the pen 101 when the pen is used to mteract with a netpage 1 The coded data 3 of the tags 4 is read by the pen when it is used to execute a movement, such as a stroke The data allows the identity of the particular page and associated mteractive element to be determined and an mdication of the relative positioning of the pen relative to the page to be obtained The mdicatmg data is transmitted to the pnnter, where it resolves, via the DNS, the page ID 50 of the stroke mto the network address of the netpage page server 10 which mamtams the correspondmg page mstance 830 It then transmits the stroke to the page server If the page was recently identified m an earlier stroke, then the pnnter may already have the address of the relevant page server m its cache Each netpage consists of a compact page layout mamtamed persistently by a netpage page server (see below) The page layout refers to objects such as unages, fonts and pieces of text, typically stored elsewhere on the netpage network When the page server receives the stroke from the pen, it retneves the page descnption to which the stroke applies, and determines which element of the page descnption the stroke mtersects It is then able to mterpret the stroke m the context of the type of the relevant element A "click" is a stroke where the distance and tune between the pen down position and the subsequent pen up position are both less than some small maximum An object which is activated by a click typically requues a click to be activated, and accordmgly, a longer stroke is ignored The failure of a pen action, such as a "sloppy" click, to register is mdicated by the lack of response from the pen's "ok" LED There are two lands of mput elements m a netpage page descπption hyperlinks and form fields Input through a form field can also tngger the activation of an associated hyperlink 1.7.1 Hyperlinks A hyperlmk is a means of sending a message to a remote application, and typically elicits a pnnted response m the netpage system A hyperlink element 844 identifies the application 71 which handles activation of the hyperlink, a link ID 54 which identifies the hyperlink to the application, an "alias reqmred" flag which asks the system to mclude the user's application alias ID 65 m the hyperlink activation, and a descnption which is used when the hyperlmk is recorded as a favoπte or appears m the user's history The hyperlmk element class diagram is shown m Figure 29 When a hyperlmk is activated, the page server sends a request to an application somewhere on the network The application is identified by an application ID 64, and the application ID is resolved m the normal way via the DNS - 18 - There are three types of hyperlinks general hyperlinks 863, form hyperlinks 865, and selection hyperlinks 864, as shown m Figure 30 A general hyperlink can implement a request for a linked document, or may simply signal a preference to a server A form hyperlink submits the corresponding form to the application A selection hyperlink submits the current selection to the application If the current selection contams a smgle-word piece of text, for example, the application may retum a smgle-page document givmg the word's meanmg withm the context m which it appears, or a translation mto a different language Each hyperlmk type is characterized by what information is submitted to the application The correspondmg hyperlink mstance 862 records a transaction ID 55 which can be specific to the page mstance on which the hyperlink mstance appears The transaction ID can identify user-specific data to the application, for example a "shopping cart" of pending purchases mamtamed by a purchasing application on behalf of the user The system mcludes the pen's current selection 826 m a selection hyperlink activation The system mcludes the content of the associated form mstance 868 m a form hyperlmk activation, although if the hyperlink has its "submit delta" attnbute set, only mput smce the last form submission is mcluded The system mcludes an effective return path m all hyperlink activations A hyperlinked group 866 is a group element 838 which has an associated hyperlink, as shown m Figure 31 When mput occurs through any field element m the group, the hyperlink 844 associated with the group is activated A hyperlinked group can be used to associate hyperlink behavior with a field such as a checkbox It can also be used, m conjunction with the "submit delta" attnbute of a foπn hyperlmk, to provide continuous mput to an application It can therefore be used to support a "blackboard" mteraction model, I e where mput is captured and therefore shared as soon as it occurs 1.7.2 Forms A form defines a collection of related mput fields used to capture a related set of inputs through a pnnted netpage A foπn allows a user to submit one or more parameters to an application software program runiung on a server A form 867 is a group element 838 m the document hierarchy It ultimately contams a set of terminal field elements 839 A form mstance 868 represents a pπnted mstance of a form It consists of a set of field mstances 870 which correspond to the field elements 845 of the form Each field mstance has an associated value 871, whose type depends on the type of the correspondmg field element Each field value records mput through a particular pnnted form mstance, l e through one or more pπnted netpages The foπn class diagram is shown m Figure 32 Each form mstance has a status 872 which mdicates whether the form is active, frozen, submitted, void or expued A form is active when first pπnted A form becomes frozen once it is signed A form becomes submitted once one of its submission hyperlinks has been activated, unless the hyperlink has its "submit delta" attribute set A form becomes void when the user mvokes a void form, reset form or duplicate form page command A form expues when the tune the form has been active exceeds the form's specified lifetime While the form is active, form mput is allowed Input through a form which is not active is mstead captured m the background field 833 of the relevant page mstance When the form is active or frozen, form submission is allowed Any attempt to submit a form when the form is not active or frozen is rejected, and mstead elicits an form status report Each form mstance is associated (at 59) with any form mstances deπved from it, thus providmg a version history This allows all but the latest version of a form m a particular tune penod to be excluded from a search All mput is captured as digital ink Digital ink 873 consists of a set of timestamped stroke groups 874, each of which consists of a set of styled strokes 875 Each stroke consists of a set of timestamped pen positions 876, each of which also mcludes pen onentation and mb force The digital ink class diagram is shown m Figure 33 A field element 845 can be a checkbox field 877, a text field 878, a drawing field 879, or a signature field - 19 - 880 The field element class diagram is shown m Figure 34 Any digital ink captured m a field's zone 58 is assigned to the field A checkbox field has an associated boolean value 881, as shown m Figure 35 Any mark (a tick, a cross, a stroke, a fill zigzag, etc ) captured m a checkbox field's zone causes a true value to be assigned to the field's value A text field has an associated text value 882, as shown m Figure 36 Any digital ink captured m a text field's zone is automatically converted to text via onlme handwntmg recogmtion, and the text is assigned to the field's value Onlme handwntmg recogmtion is well-understood (see for example Tapper., C , C Y Suen and T Wakahara, "The State of the Art m On-Line Handwntmg Recogmtion", IEEE Transactions on Pattern Analysis and Machine Intelligence, Vol 12, No 8, August 1990) A signature field has an associated digital signature value 883, as shown m Figure 37 Any digital ink captured m a signature field's zone is automatically venfied with respect to the identity of the owner of the pen, and a digital signature of the content of the form of which the field is part is generated and assigned to the field's value The digital signature is generated using the pen user's pπvate signature key specific to the application which owns the form Onlme signature venfication is well-understood (see for example Plamondon, R and G Lorette, "Automatic Signature Venfication and Wnter Identification - The State of the Art", Pattern Recogmtion, Vol 22, No 2, 1989) A field element is hidden if its "hidden" attnbute is set A hidden field element does not have an mput zone on a page and does not accept mput It can have an associated field value which is mcluded m the form data when the form containing the field is submitted "Editing" commands, such as stπke-throughs mdicatmg deletion, can also be recognized m form fields Because the handwntmg recogmtion algonthm works "onlme" (I e with access to the dynamics of the pen movement), rather than "offline" (l e with access only to a bitmap of pen markings), it can recognize run-on discretely- wntten characters with relatively high accuracy, without a wnter-dependent trauung phase A wnter-dependent model of handwntmg is automatically generated over time, however, and can be generated up-front if necessary, Digital ink, as already stated, consists of a sequence of strokes Any stroke which starts m a particular element's zone is appended to that element's digital ink stream, ready for mterpretation Any stroke not appended to an object's digital ink stream is appended to the background field's digital ink stream Digital ink captured m the background field is mterpreted as a selection gesture Cucumscπption of one or more objects is generally mterpreted as a selection of the cucumscnbed objects, although the actual mterpretation is application-specific Table 2 summanses these vanous pen interactions with a netpage The system mamtams a current selection for each pen The selection consists simply of the most recent stroke captured m the background field The selection is cleared after an inactivity timeout to ensure predictable - 20 - behavior The raw digital mk captured m every field is retained on the netpage page server and is optionally transmitted with the form data when the form is submitted to the application This allows the application to interrogate the raw digital mk should it suspect the oπgmal conversion, such as the conversion of handwntten text This can, for example, mvolve human mtervention at the application level for forms which fail certam application-specific consistency checks As an extension to this, the enure background area of a form can be designated as a drawing field The application can then decide, on the basis of the presence of digital ink outside the explicit fields of the form, to route the form to a human operator, on the assumption that the user may have mdicated amendments to the filled-m fields outside of those fields Figure 38 shows a flowchart of the process of handlmg pen mput relative to a netpage The process consists of receiving (at 884) a stroke from the pen, identifymg (at 885) the page mstance 830 to which the page ID 50 m the stroke refers, retnevmg (at 886) the page descnption 5, identifymg (at 887) a formatted element 839 whose zone 58 the stroke mtersects, determuung (at 888) whether the formatted element corresponds to a field element, and if so appendmg (at 892) the received stroke to the digital ink of the field value 871, interpreting (at 893) the accumulated digital mk of the field, and determuung (at 894) whether the field is part of a hyperlinked group 866 and if so activating (at 895) the associated hyperlink, alternatively determining (at 889) whether the formatted element coπesponds to a hyperlmk element and if so activating (at 895) the correspondmg hyperlmk, alternatively, m the absence of an mput field or hyperlmk, appendmg (at 890) the received stroke to the digital ink of the background field 833, and copying (at 891) the received stroke to the current selection 826 of the current pen, as mamtamed by the registration server Figure 38a shows a detailed flowchart of step 893 m the process shown m Figure 38, where the accumulated digital ink of a field is mterpreted accordmg to the type of the field The process consists of determuung (at 896) whether the field is a checkbox and (at 897) whether the digital ink represents a checkmark, and if so assignmg (at 898) a true value to the field value, alternatively determuung (at 899) whether the field is a text field and if so converting (at 900) the digital ink to computer text, with the help of the appropnate registration server, and assignmg (at 901) the converted computer text to the field value, alternatively determuung (at 902) whether the field is a signature field and if so venfying (at 903) the digital ink as the signature of the pen's owner, with the help of the appropnate registration server, creating (at 904) a digital signature of the contents of the correspondmg form, also with the help of the registration server and usmg the pen owner's pnvate signature key relatmg to the correspondmg application, and assignmg (at 905) the digital signature to the field value 1.7.3 Page Server Commands A page server command is a command which is handled locally by the page server It operates duectly on form, page and document mstances A page server command 907 can be a void form command 908, a duplicate form command 909, a reset form command 910, a get form status command 911, a duplicate page command 912, a reset page command 913, a get page status command 914, a duplicate document command 915, a reset document command 916, or a get document status command 917, as shown m Figure 39 A void form command voids the correspondmg form mstance A duplicate form command voids the corresponding form mstance and then produces an active pnnted copy of the current form mstance with field values preserved The copy contams the same hyperlink transaction IDs as the oπgmal, and so is indistinguishable from the oπgmal to an application A reset form command voids the correspondmg form mstance and then produces an active pπnted copy of the form mstance with field values discarded A get form status command produces a pnnted report on the status of the correspondmg form mstance, mcludmg who published it, when it was pπnted, for whom it was pπnted, - 21 - and the form status of the form mstance Smce a form hyperlink mstance contams a transaction ID, the application has to be mvolved m producmg a new form instance A button requesting a new form mstance is therefore typically implemented as a hyperlmk A duplicate page command produces a pnnted copy of the corresponding page mstance with the background field value preserved If the page contams a form or is part of a form, then the duplicate page command is mterpreted as a duplicate form command A reset page command produces a pπnted copy of the correspondmg page mstance with the background field value discarded If the page contams a form or is part of a form, then the reset page command is interpreted as a reset form command A get page status command produces a pnnted report on the status of the correspondmg page mstance, mcludmg who published it, when it was pnnted, for whom it was pπnted, and the status of any forms it contams or is part of The netpage logo which appears on every netpage is usually associated with a duplicate page element When a page mstance is duplicated with field values preserved, field values are pnnted m theu native form, l e a checkmark appears as a standard checkmark graphic, and text appears as typeset text Only drawings and signatures appear m theu ongmal form, with a signature accompanied by a standard graphic mdicatmg successful signature venfication A duplicate document command produces a pnnted copy of the corresponding document mstance with background field values preserved If the document contams any forms, then the duplicate document command duplicates the forms m the same way a duplicate form command does A reset document command produces a pπnted copy of the correspondmg document mstance with background field values discarded If the document contams any forms, then the reset document command resets the forms m the same way a reset form command does A get document status command produces a pπnted report on the status of the correspondmg document mstance, mcludmg who published it, when it was pπnted, for whom it was pnnted, and the status of any forms it contams If the page server command's "on selected" attnbute is set, then the command operates on the page identified by the pen's current selection rather than on the page containing the command This allows a menu of page server commands to be pnnted If the target page doesn't contam a page server command element for the designated page server command, then the command is ignored An application can provide application-specific handlmg by embeddmg the relevant page server command element m a hyperlinked group The page server activates the hyperlmk associated with the hyperlinked group rather than executing the page server command A page server command element is hidden if its "hidden" attnbute is set A hidden command element does not have an mput zone on a page and so cannot be activated directly by a user It can, however, be activated via a page server command embedded in a different page, if that page server command has its "on selected" attπbute set 1.8 STANDARD FEATURES OF NETPAGES In the preferred form, each netpage is pπnted with the netpage logo at the bottom to mdicate that it is a netpage and therefore has mteractive properties The logo also acts as a copy button In most cases pressmg the logo produces a copy of the page In the case of a form, the button produces a copy of the entue form And m the case of a secure document, such as a ticket or coupon, the button elicits an explanatory note or advertismg page The default smgle-page copy function is handled directly by the relevant netpage page server Special copy functions are handled by linking the logo button to an application 1.9 USER HELP SYSTEM In a preferred embodiment, the netpage pnnter has a smgle button labelled "Help" When pressed it elicits a smgle page of information, mcludmg • status of pπnter connection - 22 - • status of pnnter consumables • top-level help menu document function menu • top-level netpage network directory The help menu provides a hierarchical manual on how to use the netpage system The document function menu mcludes the followmg functions • pπnt a copy of a document • pnnt a clean copy of a form • pπnt the status of a document A document function is initiated by simply pressmg the button and then touching any page of the document The status of a document mdicates who published it and when, to whom it was delivered, and to whom and when it was subsequently submitted as a form The netpage network directory allows the user to navigate the hierarchy of publications and services on the network As an alternative, the user can call the netpage network "900" number "yellow pages" and speak to a human operator The operator can locate the desired document and route it to the user's pπnter Dependmg on the document type, the publisher or the user pays the small "yellow pages" service fee The help page is obviously unavailable if the pπnter is unable to pπnt In this case the "error" light is lit and the user can request remote diagnosis over the network 2 PERSONALIZED PUBLICATION MODEL In the followmg descnption, news is used as a canonical publication example to illustrate personalization mechamsms m the netpage system Although news is often used m the limited sense of newspaper and newsmagazme news, the mtended scope m the present context is wider In the netpage system, the editonal content and the advertismg content of a news publication are personalized usmg different mechanisms The editonal content is personalized accordmg to the reader's explicitly stated and implicitly captured mterest profile The advertismg content is personalized accordmg to the reader's locality and demographic 2.1 EDITORIAL PERSONALIZATION A subscnber can draw on two lands of news sources those that deliver news publications, and those that deliver news streams While news publications are aggregated and edited by the publisher news streams are aggregated either by a news publisher or by a specialized news aggregator News publications typically correspond to traditional newspapers and newsmagazmes, while news streams can be many and vaned a "raw" news feed from a news service, a cartoon stnp, a freelance wnter' s column, a friend's bulletin board, or the reader's own e-mail The netpage publication server supports the publication of edited news publications as well as the aggregation of multiple news streams By handlmg the aggregation and hence the formattmg of news streams selected duectly by the reader, the server is able to place advertismg on pages over which it otherwise has no editonal control The subscnber builds a daily newspaper by selecting one or more contnbuting news publications, and creating a personalized version of each The resultmg daily editions are pπnted and bound together mto a smgle newspaper The vanous members of a household typically express theu different mterests and tastes by selecting different daily publications and then customizmg them For each publication, the reader optionally selects specific sections Some sections appear daily, while others appear weekly The daily sections available from The New York Tunes onlme, for example, mclude "Page One Plus", "National", "International", "Opinion", "Busmess", "Arts/Living", "Technology", and "Sports" The set of available sections is specific to a publication, as is the default subset - 23 - The reader can extend the daily newspaper by creating custom sections, each one drawing on any number of news streams Custom sections might be created for e-mail and friends' announcements ("Personal"), or for momtonng news feeds for specific topics ("Alerts" or "Clippings") For each section, the reader optionally specifies its size, either qualitatively (e g short, medium, or long), or numencally (l e as a limit on its number of pages), and the desued proportion of advertismg, either qualitatively (e g high, normal, low, none), or numencally (I e as a percentage) The reader also optionally expresses a preference for a large number of shorter articles or a small number of longer articles Each article is ideally wntten (or edited) m both short and long forms to support this preference An article may also be wntten (or edited) m different versions to match the expected sophistication of the reader, for example to provide children's and adults' versions The appropnate version is selected accordmg to the reader's age The reader can specify a "reading age" which takes precedence over theu biological age The articles which make up each section are selected and pnontized by the editors, and each is assigned a useful lifetime Bv default they are delivered to all relevant subscnbers, m pnonty order, subject to space constraints m the subscnbers' editions In sections where it is appropnate, the reader may optionally enable collaborative filtenng This is then applied to articles which have a sufficiently long lifetime Each article which qualifies for collaborative filtenng is pnnted with rating buttons at the end of the article The buttons can provide an easy choice (e g "liked" and "disliked'), making it more likely that readers will bother to rate the article Articles with high pnonties and short lifetimes are therefore effectively considered essential reading by the editors and are delivered to most relevant subscnbers The reader optionally specifies a serendipity factor, either qualitatively (e g do or don't surpnse me), or numencally A high serendipity factor lowers the threshold used for matching dunng collaborative filtenng A high factor makes it more likely that the correspondmg section will be filled to the reader's specified capacity A different serendipity factor can be specified for different days of the week The reader also optionally specifies topics of particular mterest within a section, and this modifies the pnonties assigned by the editors The speed of the reader's Internet connection affects the quality at which unages can be delivered The reader optionally specifies a preference for fewer images or smaller images or both If the number or size of images is not reduced, then images may be delivered at lower quality (l e at lower resolution or with greater compression) At a global level, the reader specifies how quantities, dates, tunes and monetary values are localized This mvolves specifying whether units are unpenal or metnc, a local tunezone and tune format, and a local currency, and whether the localization consist of in situ translation or annotation These preferences are deπved from the reader's locality by default To reduce reading difficulties caused by poor eyesight, the reader optionally specifies a global preference for a larger presentation Both text and images are scaled accordingly, and less information is accommodated on each page The language m which a news publication is published, and its corresponding text encoding, is a property of the publication and not a preference expressed by the user However, the netpage system can be configured to provide automatic translation services m vanous guises 2.2 ADVERTISING LOCALIZATION AND TARGETING The personalization of the editonal content duectly affects the advertismg content, because advertismg is typically placed to exploit the editonal context Travel ads, for example, are more likely to appear m a travel section - 24 - than elsewhere The value of the editonal content to an advertiser (and therefore to the publisher) lies m its ability to attract large numbers of readers with the πght demographics Effective advertismg is placed on the basis of locality and demographics Locality determines proximity to particular services, retailers etc , and particular mterests and concerns associated with the local community and envnonment Demographics determme general mterests and preoccupations as well as likely spending patterns A news publisher's most profitable product is advertismg "space", a multi-dunensional entity determined by the publication's geographic coverage, the size of its readership, its readership demographics, and the page area available for advertismg In the netpage system, the netpage publication server computes the approximate multi-dimensional size of a publication's saleable advertising space on a per-section basis, takmg mto account the publication's geographic coverage, the section's readership, the size of each reader's section edition, each reader's advertismg proportion, and each reader's demographic In companson with other media, the netpage system allows the advertismg space to be defined m greater detail, and allows smaller pieces of it to be sold separately It therefore allows it to be sold at closer to its true value For example, the same advertismg "slot" can be sold m varying proportions to several advertisers, with individual readers' pages randomly receivmg the advertisement of one advertiser or another, overall preserving the proportion of space sold to each advertiser The netpage system allows advertismg to be linked duectly to detailed product mformation and onlme purchasing It therefore reuses the intrinsic value of the advertismg space Because personalization and localization are handled automatically by netpage publication servers, an advertismg aggregator can provide arbitranly broad coverage of both geography and demographics The subsequent disaggregation is efficient because it is automatic This makes it more cost-effective for publishers to deal with advertismg aggregators than to duectly capture advertismg Even though the advertismg aggregator is takmg a proportion of advertismg revenue, publishers may find the change profit-neutral because of the greater efficiency of aggregation The advertismg aggregator acts as an mtermediary between advertisers and publishers, and may place the same advertisement m multiple publications It is worth noting that ad placement m a netpage publication can be more complex than ad placement m the publication's traditional counterpart, because the publication's advertismg space is more complex While ignoring the full complexities of negotiations between advertisers, advertismg aggregators and publishers, the preferred form of the netpage system provides some automated support for these negotiations, mcludmg support for automated auctions of advertismg space Automation is particularly desuable for the placement of advertisements which generate small amounts of mcome, such as small or highly localized advertisements Once placement has been negotiated, the aggregator captures and edits the advertisement and records it on a netpage ad server Correspondingly, the publisher records the ad placement on the relevant netpage publication server When the netpage publication server lays out each user's personalized publication, it picks the relevant advertisements from the netpage ad server 2.3 USER PROFILES 2.3.1 Information Filtering The personalization of news and other publications relies on an assortment of user-specific profile information, mcludmg • publication custoπuzations • collaborative filtenng vectors • contact details - 25 - • presentation preferences The customization of a publication is typically publication-specific, and so the customization information is mamtamed by the relevant netpage publication server A collaborative filtenng vector consists of the user's ratings of a number of news items It is used to correlate different users' mterests for the purposes of making recommendations Although there are benefits to ma tauung a smgle collaborative filtenng vector mdependently of any particular publication, there are two reasons why it is more practical to mamtam a separate vector for each publication there is likely to be more overlap between the vectors of subscnbers to the same publication than between those of subscnbers to different publications, and a publication is likely to want to present its users' collaborative filtenng vectors as part of the value of its brand, not to be found elsewhere Collaborative filtenng vectors are therefore also mamtamed by the relevant netpage publication server Contact details, mcludmg name, street address, ZIP Code, state, country, telephone numbers, are global by nature, and are mamtamed by a netpage registration server Presentation preferences, mcludmg those for quantities, dates and tunes, are likewise global and mamtamed m the same way The localization of advertismg relies on the locality mdicated m the user's contact details, while the targeting of advertismg relies on personal mformation such as date of bum, gender, maπtal status, mcome, profession, education, or qualitative denvatives such as age range and mcome range For those users who choose to reveal personal information for advertismg purposes, the mformation is mamtamed by the relevant netpage registration server In the absence of such mformation, advertismg can be targeted on the basis of the demographic associated with the user's ZIP or ZIP+4 Code Each user, pen, pπnter, application provider and application is assigned its own umque identifier, and the netpage registration server mamtams the relationships between them, as shown m Figures 21, 22, 23 and 24 For registration purposes, a publisher is a special land of application provider, and a publication is a special land of application Each user 800 may be authonzed to use any number of pnnters 802, and each pnnter may allow any number of users to use it Each user has a smgle default pnnter (at 66), to which penodical publications are delivered by default, whilst pages pπnted on demand are delivered to the pπnter through which the user is interacting The server keeps track of which publishers a user has authonzed to pnnt to the user's default pnnter A publisher does not record the ID of any particular pnnter, but mstead resolves the ID when it is required When a user subscnbes 808 to a publication 807, the publisher 806 (l e application provider 803) is authonzed to pπnt to a specified pnnter or the user's default pnnter This authorization can be revoked at any tune by the user Each user may have several pens 801, but a pen is specific to a smgle user If a user is authoπzed to use a particular pnnter, then that pnnter recognizes any of the user's pens The pen ID is used to locate the correspondmg user profile mamtamed by a particular netpage registration server, via the DNS m the usual way A Web terminal 809 can be authoπzed to pnnt on a particular netpage pπnter, allowmg Web pages and netpage documents encountered dunng Web browsmg to be conveniently pnnted on the nearest netpage pπnter The netpage system can collect, on behalf of a pnnter provider, fees and commissions on mcome earned through publications pnnted on the provider's pπnters Such mcome can mclude advertismg fees, click-through fees, e- commerce commissions, and transaction fees If the pπnter is owned by the user, then the user is the pπnter provider Each user also has a netpage account 820 which is used to accumulate micro-debits and credits (such as those descnbed in the preceding paragraph), contact details 815, mcludmg name, address and telephone numbers, global - 26 - preferences 816, mcludmg pnvacy, delivery and localization settings, any number of biometnc records 817, containing the user's encoded signature 818, fingerprint 819 etc, a handwnting model 819 automatically mamtamed by the system, and SET payment card accounts 821 with which e-commerce payments can be made 2.3.2 Favorites List A netpage user can mamtam a list 922 of "favoπtes" - links to useful documents etc on the netpage network The list is mamtamed by the system on the user's behalf It is organized as a hierarchy of folders 924, a preferrred embodiment of which is shown m the class diagram m Figure 41 2.3.3 History List The system mamtams a history list 929 on each user's behalf, containing links to documents etc accessed by the user through the netpage system It is organized as a date-ordered list, a preferred embodiment of which is shown m the class diagram in Figure 42 2.4 INTELLIGENT PAGE LAYOUT The netpage publication server automatically lays out the pages of each user's personalized publication on a secϋon-by-section basis Smce most advertisements are m the form of pre-formatted rectangles, they are placed on the page before the editonal content The advertismg ratio for a section can be achieved with wildly varying advertismg ratios on individual pages withm the section, and the ad layout algonthm exploits this The algonthm is configured to attempt to co-locate closely tied editonal and advertismg content, such as placmg ads for roofing matenal specifically withm the publication because of a special feature on do-it-yourself roofing rep-urs The editonal content selected for the user, mcludmg text and associated images and graphics, is then laid out according to vanous aesthetic rules The entue process, mcludmg the selection of ads and the selection of editonal content, must be iterated once the layout has converged, to attempt to more closely achieve the user's stated section size preference The section size preference can, however, be matched on average over tune, allowing significant day-to-day vaπations 2.5 DOCUMENT FORMAT Once the document is laid out, it is encoded for efficient distnbution and persistent storage on the netpage network The primary efficiency mechanism is the separation of information specific to a smgle user's edition and information shared between multiple users' editions The specific information consists of the page layout The shared information consists of the objects to which the page layout refers, mcludmg images, graphics, and pieces of text A text object contams fully-formatted text represented m the Extensible Markup Language (XML) usmg the Extensible Stylesheet Language (XSL) XSL provides precise control over text formattmg mdependently of the region mto which the text is bemg set, which m this case is bemg provided by the layout The text object contams embedded language codes to enable automatic translation, and embedded hyphenation hints to aid with paragraph formattmg An unage object encodes an image m the JPEG 2000 wavelet-based compressed image format A graphic object encodes a 2D graphic m Scalable Vector Graphics (SVG) format The layout itself consists of a senes of placed image and graphic objects, linked textflow objects through which text objects flow, hyperlinks and mput fields as descnbed above, and watermark regions These layout objects are summarized m Table 3 The layout uses a compact format suitable for efficient distnbution and storage Table 3 - netpage layout objects Layout Attribute Format of object linked object Image Position Image object ID JPEG 2000 ■ 27 - 2.6 DOCUMENT DISTRIBUTION As descnbed above, for purposes of efficient distπbution and persistent storage on the netpage network, a user-specific page layout is separated from the shared objects to which it refers When a subscπbed publication is ready to be distnbuted, the netpage publication server allocates, with the help of the netpage ID server 12, a umque ID for each page, page mstance, document, and document mstance The server computes a set of optimized subsets of the shared content and creates a multicast channel for each subset, and then tags each user-specific lavout with the names of the multicast channels which will carry the shared content used by that layout The server then pomtcasts each user's layouts to that user's pnnter via the appropnate page server, and when the pomtcastmg is complete, multicasts the shared content on the specified channels After receiving its pomtcast, each page server and pnnter subscnbes to the multicast channels specified m the page layouts Dunng the multicasts, each page server and pπnter extracts from the multicast streams those objects refeπed to by its page layouts The page servers persistently archive the received page layouts and shared content Once a pnnter has received all the objects to which its page lavouts refer, the pnnter re-creates the fully- populated layout and then rastenzes and pπnts it Under normal cucumstances, the pπnter pπnts pages faster than they can be delivered Assummg a quarter of each page is covered with images, the average page has a size of less than 400KB The printer can therefore hold m excess of 100 such pages m its mtemal 64MB memory, allowmg for temporary buffers etc The pπnter pπnts at a rate of one page per second This is equivalent to 400KB or about 3Mbit of page data per second, which is similar to the highest expected rate of page data delivery over a broadband network Even under abnormal cucumstances, such as when the pnnter runs out of paper, it is likely that the user will be able to replemsh the paper supply before the printer's 100-page mtemal storage capacity is exhausted However, if the pπnter' s mtemal memory does fill up, then the pnnter will be unable to make use of a multicast when it first occurs The netpage publication server therefore allows pnnters to submit requests for re- multicasts When a cntical number of requests is received or a tuneout occurs, the server re-multicasts the correspondmg shared objects Once a document is pnnted, a pnnter can produce an exact duplicate at any tune by retnevmg its page layouts and contents from the relevant page server 2.7 ON-DEMAND DOCUMENTS When a netpage document is requested on demand, it can be personalized and delivered m much the same way as a penodical However, smce there is no shared content, delivery is made duectly to the requestmg pπnter without the use of multicast When a non-netpage document is requested on demand, it is not personalized, and it is delivered via a designated netpage formattmg server which reformats it as a netpage document A netpage formatting server is a special - 28 - mstance of a netpage publication server The netpage formattmg server has knowledge of vanous Internet document formats, mcludmg Adobe's Portable Document Format (PDF), and Hypertext Markup Language (HTML) In the case of HTML, it can make use of the higher resolution of the pnnted page to present Web pages m a multi-column format, with a table of contents It can automatically mclude all Web pages duectly linked to the requested page The user can tune this behavior via a preference The netpage formattmg server makes standard netpage behavior, mcludmg interactivity and persistence, available on any Internet document, no matter what its ongm and format It hides knowledge of different document formats from both the netpage pπnter and the netpage page server, and hides knowledge of the netpage system from Web servers 3 SECURITY 3.1 CRYPTOGRAPHY Cryptography is used to protect sensitive information, both in storage and m transit, and to authenticate parties to a transaction There are two classes of cryptography m widespread use secret-key cryptography and public-key cryptography The netpage network uses both classes of cryptography Secret-key cryptography, also referred to as symmetnc cryptography, uses the same key to encrypt and decrypt a message Two parties wishing to exchange messages must first arrange to securely exchange the secret key Public-key cryptography, also referred to as asymmetnc cryptography, uses two encryption keys The two keys are mathematically related m such a way that any message encrypted usmg one key can only be decrypted usmg the other key One of these keys is then published, while the other is kept pnvate The public key is used to encrypt any message mtended for the holder of the pπvate key Once encrypted usmg the public key, a message can only be decrypted usmg the pπvate key Thus two parties can securely exchange messages without first havmg to exchange a secret key To ensure that the pπvate key is secure, it is normal for the holder of the pπvate key to generate the key pan Public-key cryptography can be used to create a digital signature The holder of the pnvate key can create a known hash of a message and then encrypt the hash using the pπvate key Anyone can then veπfy that the encrypted hash constitutes the "signature" of the holder of the pnvate key with respect to that particular message by decryptmg the encrypted hash usmg the public key and venfymg the hash agamst the message If the signature is appended to the message, then the recipient of the message can veπfy both that the message is genuine and that it has not been altered m transit To make public-key cryptography work, there has to be a way to distnbute public keys which prevents impersonation This is normally done usmg certificates and certificate authonties A certificate authonty is a trusted third party which authenticates the connection between a public key and someone's identity The certificate authonty veπfies the person's identity by examuung identity documents, and then creates and signs a digital certificate containing the person's identity details and public key Anyone who trusts the certificate authonty can use the public key m the certificate with a high degree of certainty that it is genmne They just have to venfy that the certificate has mdeed been signed by the certificate authonty, whose public key is well-known In most transaction envuonments, public-key cryptography is only used to create digital signatures and to securely exchange secret session keys Secret-key cryptography is used for all other purposes In the following discussion, when reference is made to the secure transmission of mformation between a netpage pnnter and a server, what actually happens is that the pnnter obtams the server's certificate, authenticates it with reference to the certificate authonty, uses the public key-exchange key m the certificate to exchange a secret session key with the server, and then uses the secret session key to encrypt the message data A session key, by definition, can have an arbitranly short lifetime - 29 - 3.2 NETPAGE PRINTER SECURITY Each netpage pnnter is assigned a pau of umque identifiers at tune of manufacture which are stored m read-only memory m the pnnter and in the netpage registration server database The first ID 62 is public and umquely identifies the pπnter on the netpage network The second ID is secret and is used when the pπnter is first registered on the network When the pπnter connects to the netpage network for the first tune after installation, it creates a signature pubhc/pπvate key pau It transmits the secret ID and the public key securely to the netpage registration server The server compares the secret ID against the pπnter' s secret ID recorded m its database, and accepts the registration if the IDs match It then creates and signs a certificate containing the pπnter' s public ID and public signature key, and stores the certificate m the registration database The netpage registration server acts as a certificate authonty for netpage pπnters, smce it has access to secret information allowing it to venfy pnnter identity When a user subscnbes to a publication, a record is created m the netpage registration server database authorizing the publisher to pnnt the publication to the user's default pnnter or a specified pnnter Every document sent to a pnnter via a page server is addressed to a particular user and is signed by the publisher usmg the publisher's pnvate signature key The page server venfies, via the registration database, that the publisher is authoπzed to deliver the publication to the specified user The page server veπfies the signature usmg the publisher's public key, obtained from the publisher's certificate stored m the registration database The netpage registration server accepts requests to add pnntmg authorizations to the database, so long as those requests are initiated via a pen registered to the pnnter 3.3 NETPAGE PEN SECURITY Each netpage pen is assigned a umque identifier at tune of manufacture which is stored m read-only memory in the pen and m the netpage registration server database The pen ID 61 umquely identifies the pen on the netpage network A netpage pen can "know" a number of netpage pπnters, and a pπnter can "know" a number of pens A pen commumcates with a pnnter via a radio frequency signal whenever it is withm range of the printer Once a pen and pπnter are registered, they regularly exchange session keys Whenever the pen transmits digital ink to the pπnter, the digital ink is always encrypted usmg the appropnate session key Digital mk is never transmitted m the clear A pen stores a session key for every pnnter it knows, mdexed bv pπnter ID, and a pπnter stores a session key for every pen it knows, mdexed by pen ID Both have a large but finite storage capacity for session keys, and will forget a session key on a least-recently-used basis if necessary When a pen comes within range of a pπnter, the pen and pπnter discover whether they know each other If they don't know each other, then the pπnter detemunes whether it is supposed to know the pen This might be, for example, because the pen belongs to a user who is registered to use the pnnter If the pπnter is meant to know the pen but doesn't, then it uutiates the automatic pen registration procedure If the pπnter isn't meant to know the pen, then it agrees with the pen to ignore it until the pen is placed m a charging cup, at which tune it uutiates the registration procedure In addition to its public ID, the pen contams a secret key-exchange key The key-exchange key is also recorded m the netpage registration server database at tune of manufacture Dunng registration, the pen transmits its pen ID to the pnnter, and the pπnter transmits the pen ID to the netpage registration server The server generates a session key for the pπnter and pen to use, and securely transmits the session key to the pnnter It also transmits a copy of the session key encrypted with the pen's key-exchange key The pnnter stores the session key mtemally, mdexed by the pen ID, and transmits the encrypted session key to the pen The pen stores the session key mtemally, mdexed by the - 30 - pπnter ID Although a fake pen can impersonate a pen m the pen registration protocol, only a real pen can decrypt the session key transmitted by the pπnter When a previously unregistered pen is first registered, it is of limited use until it is linked to a user A registered but "un-owned" pen is only allowed to be used to request and fill m netpage user and pen registration forms, to register a new user to which the new pen is automatically linked, or to add a new pen to an existing user The pen uses secret-key rather than public-key encryption because of hardware performance constraints m the pen 3.4 SECURE DOCUMENTS The netpage system supports the delivery of secure documents such as tickets and coupons The netpage pnnter mcludes a facility to pnnt watermarks, but will only do so on request from publishers who are smtably authoπzed The publisher mdicates its authonty to pπnt watermarks m its certificate, which the pπnter is able to authenticate The "watermark" pnntmg process uses an alternative dither matnx m specified "watermark" regions of the page Back-to-back pages contam mirror-unage watermark regions which comcide when pπnted The dither matnces used m odd and even pages' watermark regions are designed to produce an interference effect when the regions are viewed together, achieved by looking through the pnnted sheet The effect is similar to a watermark m that it is not visible when looking at only one side of the page, and is lost when the page is copied by normal means Pages of secure documents cannot be copied usmg the built-in netpage copy mechanism descnbed m Section 1 9 above This extends to copymg netpages on netpage-aware photocopiers Secure documents are typically generated as part of e-commerce transactions They can therefore mclude the user's photograph which was captured when the user registered biometnc information with the netpage registration server, as descπbed m Section 2 When presented with a secure netpage document, the recipient can venfy its authenticity by requestmg its status m the usual way The umque ID of a secure document is only vεdid for the lifetime of the document, and secure document IDs are allocated non-contiguously to prevent theu prediction by opportunistic forgers A secure document venfication pen can be developed w th built-in feedback on venfication failure, to support easy pomt-of-presentation document venfication Clearly neither the watermark nor the user's photograph are secure m a cryptographic sense They simply provide a significant obstacle to casual forgery Onlme document venfication, particularly usmg a venfication pen, provides an added level of secunty where it is needed, but is still not enurely immune to forgeπes 3.5 NON-REPUDIATION In the netpage system, forms submitted by users are delivered reliably to forms handlers and are persistently archived on netpage page servers It is therefore impossible for recipients to repudiate delivery E-commerce payments made through the system, as descπbed m Section 4, are also impossible for the payee to repudiate 4 ELECTRONIC COMMERCE MODEL 4.1 SECURE ELECTRONIC TRANSACTION (SET) The netpage system uses the Secure Elecfromc Transaction (SET) system as one of its payment systems SET, havmg been developed by MasterCard and Visa, is organized around payment cards, and this is reflected m the terminology However, much of the system is mdependent of the type of accounts bemg used In SET, cardholders and merchants register with a certificate authonty and are issued with certificates - 31 - containing their public signature keys The certificate authonty venfies a cardholder's registration details with the card issuer as appropnate, and venfies a merchant's registration details with the acqiurer as appropnate Cardholders and merchants store their respective pnvate signature keys securely on theu computers Dunng the payment process, these certificates are used to mutually authenticate a merchant and cardholder, and to authenticate them both to the payment gateway SET has not yet been adopted widely, partly because cardholder maintenance of keys and certificates is considered burdensome Interim solutions which mamtam cardholder keys and certificates on a server and give the cardholder access via a password have met with some success 4.2 SET PAYMENTS In the netpage system the netpage registration server acts as a proxy for the netpage user (l e the cardholder) m SET payment transactions The netpage system uses biometncs to authenticate the user and authorize SET payments Because the system is pen-based, the biometπc used is the user's on-lme signature, consisting of tune- varying pen position and pressure A fingerprint biometnc can also be used by designing a fmgerpnnt sensor mto the pen, although at a higher cost The type of biometnc used only affects the capture of the biometnc, not the authorization aspects of the system The first step to bemg able to make SET payments is to register the user's biometnc with the netpage registration server This is done in a controlled envuonment, for example a bank, where the biometnc can be captured at the same tune as the user's identity is venfied The biometnc is captured and stored m the registration database, linked to the user's record The user's photograph is also optionally captured and linked to the record The SET cardholder registration process is completed, and the resultmg pnvate signature key and certificate are stored m the database The user's payment card information is also stored, givmg the netpage registration server enough information to act as the user's proxy m any SET payment transaction When the user eventually supplies the biometnc to complete a payment, for example by sigmng a netpage order form, the pnnter securely transmits the order information, the pen ID and the biometnc data to the netpage registration server The server veπfies the biometnc with respect to the user identified by the pen ID, and from then on acts as the user's proxy m completing the SET payment transaction 4.3 MICRO-PAYMENTS The netpage system mcludes a mechanism for micro-payments, to allow the user to be conveniently charged for pnntmg low-cost documents on demand and for copymg copynght documents, and possibly also to allow the user to be reimbursed for expenses incurred in pnntmg advertismg matenal The latter depends on the level of subsidy already provided to the user When the user registers for e-commerce, a network account is established which aggregates micro- payments The user receives a statement on a regular basis, and can settle any outstanding debit balance usmg the standard payment mechanism The network account can be extended to aggregate subscnption fees for penodicals, which would also otherwise be presented to the user m the form of individual statements 4.4 TRANSACTIONS When a user requests a netpage m a particular application context, the application is able to embed a user- specific transaction ID 55 m the page Subsequent mput through the page is tagged with the transaction ID, and the application is thereby able to establish an appropnate context for the user's mput When mput occurs through a page which is not user-specific, however, the application must use the user's unique identity to establish a context A typical example mvolves adding items from a pre-pnnted catalog page to the user's virtual "shopping cart" To protect the user's pnvacy, however, the umque user ID 60 known to the netpage - 32 - system is not divulged to applications This is to prevent different application providers from easily correlatmg mdependently accumulated behavioral data The netpage registration server mstead mamtams an anonymous relationship between a user and an application via a umque alias ID 65, as shown m Figure 24 Whenever the user activates a hyperlink tagged with the "registered" attnbute, the netpage page server asks the netpage registration server to translate the associated application ID 64, together with the pen ID 61 , mto an alias ID 65 The alias ID is then submitted to the hyperlink's application The application mamtams state information mdexed by alias ID, and is able to reuieve user-specific state information without knowledge of the global identity of the user The system also mamtams an independent certificate and pnvate signature key for each of a user's applications, to allow it to sign application transactions on behalf of the user usmg only application-specific information To assist the system m routing product bar code (UPC) "hyperlink" activations, the system records a favoπte application on behalf of the user for any number of product types Each application is associated with an application provider, and the svstem mamtams an account on behalf of each application provider, to allow it to credit and debit the provider for click-through fees etc An application provider can be a publisher of penodical subscnbed content The system records the user's willingness to receive the subscnbed publication, as well as the expected frequency of publication 4.5 RESOURCE DESCRIPTIONS AND COPYRIGHT A preferred embodiment of a resource descnption class diagram is shown m Figure 40 Each document and content object may be descnbed by one or more resource descnptions 842 Resource descnptions use the Dublm Core metadata element set, which is designed to facilitate discovery of electronic resources Dublm Core metadata conforms to the World Wide Web Consortium (W3C) Resource Descπption Framework (RDF) A resource descπption may identify nghts holders 920 The netpage system automatically transfers copynght fees from users to πghts holders when users pnnt copynght content 5 COMMUNICATIONS PROTOCOLS A communications protocol defines an ordered exchange of messages between entities In the netpage system, entities such as pens, pπnters and servers utilise a set of defined protocols to cooperatively handle user mteraction with the netpage system Each protocol is illustrated by way of a sequence diagram m which the honzontal dimension is used to represent message flow and the vertical dimension is used to represent tune Each entity is represented by a rectangle contammg the name of the entity and a vertical column representmg the lifelme of the entity Dunng the tune an entity exists, the lifelme is shown as a dashed lme Dunng the tune an entity is active, the lifelme is shown as a double lme Because the protocols considered here do not create or destroy entities, lifelines are generally cut short as soon as an entity ceases to participate m a protocol 5.1 SUBSCRIPTION DELIVERY PROTOCOL A preferred embodiment of a subscnption delivery protocol is shown in Figure 43 A large number of users may subscπbe to a penodical publication Each user's edition may be laid out differently, but many users' editions will share common content such as text objects and image objects The subscnption delivery protocol therefore delivers document structures to mdividual pπnters via pomtcast, but delivers shared content objects via multicast The application (l e publisher) first obtams a document ID 51 for each document from an ID server 12 It then sends each document structure, mcludmg its document ID and page descnptions, to the page server 10 responsible for the document's newly allocated ID It mcludes its own application ID 64, the subscnber's alias ID 65, and the relevant set of multicast channel names It signs the message usmg its pπvate signature key - 33 - The page server uses the application ID and alias ID to obtam from the registration server the correspondmg user ID 60, the user's selected pnnter ID 62 (which may be explicitly selected for the application, or may be the user's default pnnter), and the application's certificate The application's certificate allows the page server to venfy the message signature The page server's request to the registration server fails if the application ID and alias ID don't together identify a subscnption 808 The page server then allocates document and page mstance IDs and forwards the page descnptions, mcludmg page IDs 50, to the pnnter It mcludes the relevant set of multicast channel names for the pnnter to listen to It then returns the newly allocated page IDs to the application for future reference Once the application has distnbuted all of the document structures to the subscnbers' selected pnnters via the relevant page servers, it multicasts the vanous subsets of the shared objects on the previously selected multicast channels Both page servers and pnnters momtor the appropnate multicast channels and receive theu requued content objects They are then able to populate the previously pomtcast document structures This allows the page servers to add complete documents to theu databases, and it allows the pnnters to pnnt the documents 5.2 HYPERLINK ACTIVATION PROTOCOL A preferred embodiment of a hyperlmk activation protocol is shown in Figure 45 When a user clicks on a netpage with a netpage pen, the pen communicates the click to the nearest netpage pnnter 601 The click identifies the page and a location on the page The pπnter already knows the ID 61 of the pen from the pen connection protocol The pπnter detemunes, via the DNS, the network address of the page server 10a handlmg the particular page ID 50 The address may already be m its cache if the user has recently mteracted with the same page The pπnter then forwards the pen ID, its own pπnter ID 62, the page ID and click location to the page server The page server loads the page descπption 5 identified by the page ID and detemunes which mput element's zone 58, if any, the click lies m Assummg the relevant mput element is a hyperlmk element 844, the page server then obtams the associated application ID 64 and link ID 54, and detemunes, via the DNS, the network address of the application server hosting the application 71 The page server uses the pen ID 61 to obtam the corresponding user ID 60 from the registration server 11, and then allocates a globally umque hyperlink request ID 52 and builds a hyperlmk request 934 The hvperlink request class diagram is shown m Figure 44 The hyperlink request records the IDs of the requestmg user and pnnter, and identifies the clicked hyperlink mstance 862 The page server then sends its own server ID 53, the hyperlink request ID, and the link ID to the application The application produces a response document accordmg to application-specific logic, and obtams a document ID 51 from an ID server 12 It then sends the document to the page server 10b responsible for the document's newly allocated ID, together with the requestmg page server's ID and the hyperlink request ID The second page server sends the hyperlink request ID and application ID to the first page server to obtam the correspondmg user ID and pπnter ID 62 The first page server rejects the request if the hyperlink request has expued or is for a different application The second page server allocates document instance and page IDs 50, returns the newly allocated page IDs to the application, adds the complete document to its own database, and finally sends the page descnptions to the requestmg pnnter The hyperlink mstance may mclude a meaningful transaction ID 55, m which case the first page server mcludes the transaction ID m the message sent to the application This allows the application to establish a transaction- specific context for the hyperlink activation - 34 - If the hyperlink req res a user alias, 1 e its "alias required" attribute is set, then the first page server sends both the pen ID 61 and the hyperlink's application ID 64 to the registration server 11 to obtain not just the user ID corresponding to the pen ID but also the alias ID 65 corresponding to the application ID and the user ID It mcludes the alias ID m the message sent to the application, allowmg the application to establish a user-specific context for the hyperlink activation 5.3 HANDWRITING RECOGNITION PROTOCOL When a user draws a stroke on a netpage with a netpage pen, the pen commumcates the stroke to the nearest netpage pnnter The stroke identifies the page and a path on the page The pnnter forwards the pen ID 61. its own pπnter ID 62, the page ID 50 and stroke path to the page server 10 m the usual way The page server loads the page descnption 5 identified by the page ID and deteπnmes which mput element's zone 58, if any, the stroke mtersects Assummg the relevant mput element is a text field 878, the page server appends the stroke to the text field's digital ink After a penod of mactivity m the zone of the text field, the page server sends the pen ID and the pendmg strokes to the registration server 11 for mterpretation The registration server identifies the user correspondmg to the pen, and uses the user's accumulated handwntmg model 822 to interpret the strokes as handwntten text Once it has converted the strokes to text, the registration server returns the text to the requestmg page server The page server appends the text to the text value of the text field 5.4 SIGNATURE VERIFICATION PROTOCOL Assummg the mput element whose zone the stroke mtersects is a signature field 880, the page server 10 appends the stroke to the signature field's digital ink After a penod of mactivity m the zone of the signature field, the page server sends the pen ID 61 and the pendmg strokes to the registration server 11 for venfication It also sends the application ID 64 associated with the form of which the signature field is part, as well as the form ID 56 and the current data content of the form The registration server identifies the user correspondmg to the pen, and uses the user's dynamic signature biometnc 818 to venfy the strokes as the user's signature Once it has venfied the signature, the registration server uses the application ID 64 and user ID 60 to identify the user's application-specific pnvate signature key It then uses the key to generate a digital signature of the form data, and returns the digital signature to the requestmg page server The page server assigns the digital signature to the signature field and sets the associated form's status to frozen The digital signature mcludes the alias ID 65 of the correspondmg user This allows a smgle form to capture multiple users' signatures 5.5 FORM SUBMISSION PROTOCOL A preferred embodiment of a form submission protocol is shown m Figure 46 Form submission occurs via a form hyperlink activation It thus follows the protocol defined m Section 5 2, with some form-specific additions In the case of a form hyperlink, the hyperlink activation message sent by the page server 10 to the application 71 also contams the form ID 56 and the current data content of the form If the form contains any signature fields, then the application veπfies each one by extracting the alias ID 65 associated with the correspondmg digital signature and obtaining the correspondmg certificate from the registration server 11 5.6 COMMISSION PAYMENT PROTOCOL A preferred embodiment of a commission payment protocol is shown m Figure 47 In an e-commerce envuonment, fees and commissions may be payable from an application provider to a publisher on click-throughs, transactions and sales Commissions on fees and commissions on commissions may also be - 35 - payable from the publisher to the provider of the pnnter The hyperlmk request ID 52 is used to route a fee or commission credit from the target application provider 70a (e g merchant) to the source application provider 70b (l e publisher), and from the source application provider 70b to the pnnter provider 72 The target application receives the hyperlink request ID from the page server 10 when the hyperlink is first activated, as descnbed m Section 5 2 When the target application needs to credit the source application provider, it sends the application provider credit to the ongmal page server together with the hyperlink request ID The page server uses the hyperlink request ID to identify the source application, and sends the credit on to the relevant registration server 11 together with the source application ID 64, its own server ID 53, and the hyperlink request ID The registration server credits the correspondmg application provider's account 827 It also notifies the application provider If the application provider needs to credit the pnnter provider, it sends the pnnter provider credit to the ongmal page server together with the hvperlink request ID The page server uses the hyperlink request ID to identify the pπnter, and sends the credit on to the relevant registration server together with the pπnter ID The registration server credits the correspondmg pnnter provider account 814 The source application provider is optionally notified of the identity of the target application provider, and the pnnter provider of the identity of the source application provider 6. NETPAGE PEN DESCRIPTION 6.1 PEN MECHANICS Referring to Figures 8 and 9, the pen, generally designated by reference numeral 101, mcludes a housmg 102 m the form of a plastics moulding havmg walls 103 defining an rntenor space 104 for mounting the pen components The pen top 105 is m operation rotatably mounted at one end 106 of the housmg 102 A semi-transparent cover 107 is secured to the opposite end 108 of the housmg 102 The cover 107 is also of moulded plastics, and is formed from semi-transparent matenal m order to enable the user to view the status of the LED mounted within the housing 102 The cover 107 includes a mam part 109 which substantially surrounds the end 108 of the housmg 102 and a projecting portion 110 which projects back from the mam part 109 and fits within a correspondmg slot 111 formed m the walls 103 of the housmg 102 A radio antenna 112 is mounted behind the projecting portion 110, withm the housmg 102 Screw threads 113 surrounding an aperture 113A on the cover 107 are aπanged to receive a metal end piece 114, mcludmg correspondmg screw threads 115 The metal end piece 114 is removable to enable ink cartndge replacement Also mounted within the cover 107 is a tn-color status LED 116 on a flex PCB 117 The antenna 112 is also mounted on the flex PCB 117 The status LED 116 is mounted at the top of the pen 101 for good all-around visibility The pen can operate both as a normal markmg ink pen and as a non-marking stylus An ink pen cartndge 118 with mb 119 and a stylus 120 with stylus mb 121 are mounted side by side within the housmg 102 Either the ink cartndge mb 119 or the stylus mb 121 can be brought forward through open end 122 of the metal end piece 114, by rotation of the pen top 105 Respective slider blocks 123 and 124 are mounted to the ink cartndge 118 and stylus 120, respectively A rotatable cam barrel 125 is secured to the pen top 105 m operation and arranged to rotate therewith The cam barrel 125 mcludes a cam 126 m the form of a slot withm the walls 181 of the cam barrel Cam followers 127 and 128 projecting from slider blocks 123 and 124 fit within the cam slot 126 On rotation of the cam barrel 125, the slider blocks 123 or 124 move relative to each other to project either the pen mb 119 or stylus mb 121 out through the hole 122 m the metal end piece 114 The pen 101 has three states of operation By tuπung the top 105 through 90° steps, the three states are Stylus 120 mb 121 out, • Ink cartndge 118 mb 119 out, and • Neither ink cartndge 118 b 119 out nor stylus 120 mb 121 out - 36 - A second flex PCB 129, is mounted on an electronics chassis 130 which sits withm the housmg 102 The second flex PCB 129 mounts an infrared LED 131 for providing infrared radiation for projection onto the surface An unage sensor 132 is provided mounted on the second flex PCB 129 for receiving reflected radiation from the surface The second flex PCB 129 also mounts a radio frequency chip 133, which mcludes an RF transmitter and RF receiver, and a controller chip 134 for confrollmg operation of the pen 101 An optics block 135 (formed from moulded clear plastics) sits within the cover 107 and projects an infrared beam onto the surface and receives images onto the image sensor 132 Power supply wires 136 connect the components on the second flex PCB 129 to battery contacts 137 which are mounted withm the cam barrel 125 A terminal 138 connects to the battery contacts 137 and the cam barrel 125 A three volt rechargeable battery 139 sits within the cam barrel 125 m contact with the battery contacts An mduction charging coil 140 is mounted about the second flex PCB 129 to enable recharging of the battery 139 via mduction The second flex PCB 129 also mounts an infrared LED 143 and infrared photodiode 144 for detecting displacement m the cam barrel 125 when either the stylus 120 or the ink cartndge 118 is used for writing, m order to enable a determmation of the force being applied to the surface by the pen mb 119 or stylus mb 121 The IR photodiode 144 detects light from the IR LED 143 via reflectors (not shown) mounted on the slider blocks 123 and 124 Rubber gnp pads 141 and 142 are provided towards the end 108 of the housmg 102 to assist gnpping the pen 101, and top 105 also mcludes a clip 142 for clipping the pen 101 to a pocket 6.2 PEN CONTROLLER The pen 101 is aπanged to determine the position of its mb (stylus mb 121 or ink cartπdge mb 119) by imaging, m the infrared spectrum, an area of the surface m the vicinity of the mb It records the location data from the nearest location tag, and is arranged to calculate the distance of the mb 121 or 119 from the location tab utilismg optics 135 and controller chip 134 The controller chip 134 calculates the oπentation of the pen and the mb-to-tag distance from the perspective distortion observed on the imaged tag Utilismg the RF chip 133 and antenna 112 the pen 101 can transmit the digital ink data (which is encrypted for secunty and packaged for efficient transmission) to the computing system When the pen is in range of a receiver, the digital ink data is transmitted as it is formed When the pen 101 moves out of range, digital ink data is buffered withm the pen 101 (the pen 101 cncuitry mcludes a buffer arranged to store digital mk data for approximately 12 minutes of the pen motion on the surface) and can be transmitted later The controller chip 134 is mounted on the second flex PCB 129 in the pen 101 Figure 10 is a block diagram illustrating m more detail the architecture of the controller chip 134 Figure 10 also shows representations of the RF chip 133, the image sensor 132, the tn-color status LED 116, the IR illummation LED 131, the IR force sensor LED 143, and the force sensor photodiode 144 The pen controller chip 134 mcludes a confrollmg processor 145 Bus 146 enables the exchange of data between components of the controller chip 134 Flash memory 147 and a 512 KB DRAM 148 are also mcluded An analog-to-digital converter 149 is arranged to convert the analog signal from the force sensor photodiode 144 to a digital signal An unage sensor mterface 152 mterfaces with the image sensor 132 A transceiver controller 153 and base band cucmt 154 are also mcluded to mterface with the RF chip 133 which mcludes an RF cucmt 155 and RF resonators and mductors 156 connected to the antenna 112 The confrollmg processor 145 captures and decodes location data from tags from the surface via the image sensor 132, momtors the force sensor photodiode 144, controls the LEDs 116, 131 and 143, and handles short-range radio commumcation via the radio transceiver 153 It is a medium-performance (~40MHz) general-purpose RISC processor - 37 - The processor 145, digital transceiver components (transceiver controller 153 and baseband cucmt 154), image sensor mterface 152, flash memory 147 and 512KB DRAM 148 are mtegrated m a smgle controller ASIC Analog RF components (RF cucmt 155 and RF resonators and mductors 156) are provided m the separate RF chip The unage sensor is a 215x215 pixel CCD (such a sensor is produced by Matsushita Elecfromc Corporation, and is descnbed m a paper by Itakura, K T Nobusada, N Okusenya, R Nagayoshi, and M Ozaki, "A 1mm 50k-Pιxel IT CCD Image Sensor for Miniature Camera System", IEEE Transactions on Elecfromc Devices, Volt 47, number 1, January 2000, which is incorporated herem by reference) with an IR filter The controller ASIC 134 enters a quiescent state after a penod of mactivity when the pen 101 is not m contact with a surface It mcorporates a dedicated cucmt 150 which momtors the force sensor photodiode 144 and wakes up the controller 134 via the power manager 151 on a pen-down event The radio transceiver commumcates m the unlicensed 900MHz band normally used by cordless telephones, or alternatively m the unlicensed 2 4GHz mdustnal, scientific and medical (ISM) band, and uses frequency hoppmg and collision detection to provide interference-free commumcation In an alternative embodiment, the pen mcorporates an Infrared Data Association (IrDA) mterface for short- range commumcation with a base station or netpage pnnter In a further embodiment, the pen 101 mcludes a pau of orthogonal accelerometers mounted m the normal plane of the pen 101 axis The accelerometers 190 are shown m Figures 9 and 10 m ghost outlme The provision of the accelerometers enables this embodiment of the pen 101 to sense motion without reference to surface location tags, allowmg the location tags to be sampled at a lower rate Each location tag ID can then identify an object of mterest rather than a position on the surface For example, if the object is a user mterface input element (e g a command button), then the tag ID of each location tag withm the area of the mput element can duectly identify the mput element The acceleration measured by the accelerometers m each of the x and y duections is mtegrated with respect to time to produce an instantaneous velocity and position Smce the starting position of the stroke is not known, only relative positions withm a stroke are calculated Although position integration accumulates errors m the sensed acceleration, accelerometers typically have high resolution, and the tune duration of a stroke, over which errors accumulate, is short 7. NETPAGE PRINTER DESCRIPTION 7.1 PRINTER MECHANICS The vertically-mounted netpage wallpnnter 601 is shown fully assembled m Figure 11 It prints netpages on Letter/A4 sized media usmg duplexed 8 1 -" Memjet™ pnnt engmes 602 and 603, as shown m Figures 12 and 12a It uses a straight paper path with the paper 604 passmg through the duplexed pnnt engmes 602 and 603 which pπnt both sides of a sheet simultaneously, m full color and with full bleed An mtegral bmdmg assembly 605 applies a stnp of glue along one edge of each pnnted sheet, allowmg it to adhere to the previous sheet when pressed agamst it This creates a final bound document 618 which can range in thickness from one sheet to several hundred sheets The replaceable mk cartπdge 627, shown m Figure 13 coupled with the duplexed pnnt engmes, has bladders or chambers for storing fixative, adhesive, and cyan, magenta, yellow, black and infrared inks The cartπdge also contams a micro au filter m a base molding The micro au filter mterfaces with an au pump 638 mside the pnnter via a hose 639 This provides filtered au to the prmtheads to prevent ingress of micro particles mto the Memjet™ pπntheads 350 which might otherwise clog the pnnthead nozzles By incorporating the au filter withm the cartπdge, the operational life of the filter is effectively linked to the life of the cartndge The ink cartndge is a fully recyclable product with a capacity for pnntmg and gluing 3000 pages (1500 sheets) - 38 - Refernng to Figure 12, the motorized media pick-up roller assembly 626 pushes the top sheet duectly from the media tray past a paper sensor on the first pnnt engme 602 mto the duplexed Memjet™ pnnthead assembly The two Memjet™ pnnt engmes 602 and 603 are mounted m an opposmg in-line sequential configuration along the straight paper path The paper 604 is drawn mto the first pπnt engme 602 by mtegral, powered pick-up rollers 626 The position and size of the paper 604 is sensed and full bleed pnntmg commences Fixative is pnnted simultaneously to aid drymg m the shortest possible tune The paper exits the first Memjet™ prmt engme 602 through a set of powered exit spike wheels (aligned along the straight paper path), which act agamst a rubberized roller These spike wheels contact the 'wet' pnnted surface and contmue to feed the sheet 604 mto the second Memjet™ pnnt engme 603 Referring to Figures 12 and 12a, the paper 604 passes from the duplexed pnnt engmes 602 and 603 mto the bmder assembly 605 The pnnted page passes between a powered spike wheel axle 670 with a fibrous support roller and another movable axle with spike wheels and a momentary action glue wheel The movable axle/glue assembly 673 is mounted to a metal support bracket and it is transported forward to mterface with the powered axle 670 via gears by action of a camshaft A separate motor powers this camshaft The glue wheel assembly 673 consists of a partially hollow axle 679 with a rotating coupling for the glue supply hose 641 from the ink cartndge 627 This axle 679 connects to a glue wheel, which absorbs adhesive by capillary action through radial holes A molded housmg 682 surrounds the glue wheel, with an opening at the front Pivoting side moldmgs and sprung outer doors are attached to the metal bracket and lunge out sideways when the rest of the assembly 673 is thrust forward This action exposes the glue wheel through the front of the molded housmg 682 Tension springs close the assembly and effectively cap the glue wheel dunng penods of mactivity As the sheet 604 passes mto the glue wheel assembly 673, adhesive is applied to one vertical edge on the front side (apart from the first sheet of a document) as it is transported down mto the bmdmg assembly 605 7.2 PRINTER CONTROLLER ARCHITECTURE The netpage pπnter controller consists of a confrollmg processor 750, a factory-installed or field-installed network mterface module 625, a radio transceiver (transceiver controller 753, baseband cucmt 754, RF cucmt 755, and RF resonators and mductors 756), dual raster unage processor (RIP) DSPs 757, duplexed pπnt engme confrollers 760a and 760b, flash memory 658, and 64MB of DRAM 657, as illustrated m Figure 14 The confrollmg processor handles commumcation with the network 19 and with local wueless netpage pens 101, senses the help button 617, controls the user mterface LEDs 613-616, and feeds and synchronizes the RTF DSPs 757 and pπnt engme confrollers 760 It consists of a medium-performance general-purpose microprocessor The confrollmg processor 750 commumcates with the pπnt engme confrollers 760 via a high-speed seπal bus 659 The RD? DSPs rastenze and compress page descnptions to the netpage pnnter' s compressed page format Each pnnt engme controller expands, dithers and prints page unages to its associated Memjet™ pnnthead 350 m real tune (I e at over 30 pages per mmute) The duplexed pnnt engme controllers pπnt both sides of a sheet simultaneously The master pπnt engme controller 760a controls the paper transport and momtors ink usage m conjunction with the master QA chip 665 and the ink cartndge QA chip 761 The pnnter controller's flash memory 658 holds the software for both the processor 750 and the DSPs 757, as well as configuration data This is copied to mam memory 657 at boot tune The processor 750, DSPs 757, and digital transceiver components (transceiver controller 753 and baseband cucmt 754) are mtegrated m a smgle controller ASIC 656 Analog RF components (RF cucmt 755 and RF resonators and mductors 756) are provided in a separate RF chip 762 The network mterface module 625 is separate, smce netpage pnnters allow the network connection to be factory-selected or field-selected Flash memory 658 and the 2x256Mbit - 39 - (64MB) DRAM 657 is also off-chip The pπnt engme controllers 760 are provided m separate ASICs A vanety of network mterface modules 625 are provided, each providing a netpage network mterface 751 and optionally a local computer or network mterface 752 Netpage network Internet mterfaces mclude POTS modems, Hybπd Fiber-Coax (HFC) cable modems, ISDN modems, DSL modems, satellite transceivers, current and next- generation cellular telephone transceivers, and wueless local loop (WLL) transceivers Local mterfaces mclude IEEE 1284 (parallel port), lOBase-T and 100Base-T Ethernet, USB and USB 2 0, IEEE 1394 (Fuewue), and vanous emergmg home networkmg mterfaces If an Internet connection is available on the local network, then the local network mterface can be used as the netpage network mterface The radio transceiver 753 commumcates m the unlicensed 900MHz band normally used by cordless telephones, or alternatively m the unlicensed 24GHz mdustnal, scientific and medical (ISM) band, and uses frequency hoppmg and collision detection to provide interference-free commumcation The pnnter controller optionally incorporates an Infrared Data Association (IrDA) mterface for receivmg data ' squirted" from devices such as netpage cameras In an alternative embodiment, the pnnter uses the IrDA mterface for short-range communication with smtably configured netpage pens 7.2.1 RASTERIZATION AND PRINTING Once the mam processor 750 has received and venfied the document's page layouts and page objects, it runs the appropnate RJP software on the DSPs 757 The DSPs 757 rastenze each page descπption and compress the rastenzed page image The mam processor stores each compressed page image m memory The simplest way to load-balance multiple DSPs is to let each DSP rastenze a separate page The DSPs can always be kept busy smce an arbitrary number of rastenzed pages can, m general, be stored m memory This strategy only leads to potentially poor DSP utilization when rasteπzmg short documents Watermark regions m the page descπption are rastenzed to a contone-resolution bi-level bitmap which is losslessly compressed to negligible size and which forms part of the compressed page image The infrared (IR) layer of the pπnted page contams coded netpage tags at a density of about six per mch Each tag encodes the page ID, tag ID, and control bits, and the data content of each tag is generated dunng rasterization and stored m the compressed page image The mam processor 750 passes back-to-back page images to the duplexed pπnt engme controllers 760 Each pnnt engme confroller 760 stores the compressed page image m its local memory, and starts the page expansion and pnntmg pipeline Page expansion and pnntmg is pipelined because it is unpractical to store an entire 114MB bi-level CMYK+IR page image m memory 7.2.2 PRINT ENGINE CONTROLLER The page expansion and pnntmg pipeline of the pnnt engme controller 760 consists of a high speed IEEE 1394 senal mterface 659, a standard JPEG decoder 763, a standard Group 4 Fax decoder 764, a custom halftoner/compositor unit 765, a custom tag encoder 766, a lme loader/formatter unit 767, and a custom mterface 768 to the Memjet™ pπnthead 350 The pπnt engme confroller 360 operates m a double buffered manner While one page is loaded mto DRAM 769 via the high speed senal mterface 659, the previously loaded page is read from DRAM 769 and passed through the pnnt engme controller pipeline Once the page has finished pnntmg, the page just loaded is pπnted while another page is loaded The first stage of the pipeline expands (at 763) the JPEG-compressed contone CMYK layer, expands (at 764) the Group 4 Fax-compressed bi-level black layer, and renders (at 766) the bi-level netpage tag layer accordmg to the tag format defined m section 1 2, all m parallel The second stage dithers (at 765) the contone CMYK layer and - 40 - composites (at 765) the bi-level black layer over the resultmg bi-level CMYK layer The resultant bi-level CMYK+IR dot data is buffered and formatted (at 767) for pnntmg on the Memjet™ pnnthead 350 via a set of lme buffers Most of these lme buffers are stored the off-chip DRAM The final stage prints the six channels of bi-level dot data (mcludmg fixative) to the Memjet™ pnnthead 350 via the pnnthead mterface 768 When several pπnt engme confrollers 760 are used m unison, such as m a duplexed configuration, they are synchronized via a shared lme sync signal 770 Only one pπnt engme 760, selected via the external master/slave pin 771, generates the lme sync signal 770 onto the shared lme The pπnt engme controller 760 contains a low-speed processor 772 for synchronizing the page expansion and rendering pipeline, configuring the pπnthead 350 via a low-speed seπal bus 773, and confrollmg the stepper motors 675, 676 In the 8' " versions of the netpage pπnter, the two pnnt engmes each prints 30 Letter pages per mmute along the long dimension of the page (11"), givmg a lme rate of 8 8 kHz at 1600 dpi In the 12" versions of the netpage pnnter, the two pnnt engines each prints 45 Letter pages per minute along the short dimension of the page (8'Λ"), givmg a lme rate of 10 2 kHz These lme rates are well within the operatmg frequency of the Memjet™ pnnthead, which m the current design exceeds 30 kHz 8. NETPAGE NOTE TAKING APPLICATION The netpage system, then, provides the facility for enablmg handwntten note takmg and retneval usmg a netpage notebook The netpage notebook is used m combination with a netpage pen to capture handwntten notes as digital ink m a persistent manner, and each page of the notebook is optionally signed by a trusted thud party to provide proof of recordal The handwntmg is recognized and converted to text for mdexmg purposes so that the notes can be searched by keyword, but the netpage notebook also supports searching without text conversion, allowmg the user to search on graphical information Netpage notebooks may be pre-pnnted or pπnted on demand Each netpage or netpage document used m the note takmg or retneval, such as a new notebook order page, a smgle notebook page, or even an entue multi-page notebook is a physical representation of what is referred to herem as a "form", contammg as requued the mteractive objects (hyperlinks and/or form fields) Similarly, a "notebook activity" signifies an activity m respect of a notebook, which may be, for example, ordering a new notebook, making a notebook entry, or retnevmg information form a particular notebook 8.1 APPLICATION DRAWING NOTATION Each application user mterface flow is illustrated as a collection of documents linked by command arrows A command arrow indicates that the target document is pnnted as a result of the user pressmg the corresponding command button on the source page Some command arrows are labelled with multiple commands separated by slashes (7's), mdicatmg that any one of the specified commands causes the target document to be pπnted Although multiple commands may label the same command arrow, they typically have different side-effects In application terms, it is important to distinguish between netpage documents and netpage forms Documents contam prmted information, as well as command buttons which can be pressed by the user to request further information or some other action Forms, m addition to behavmg like normal documents, also contam mput fields which can be filled m by the user They provide the system with a data mput mechanism It is also useful to distinguish between documents which contam genenc information and documents which contam information specific to a particular mteraction between the user and an application Genenc documents may be pre-pnnted publications such as magazmes sold at news stands or advertismg posters encountered m public places Forms may also be pre-pnnted, mcludmg, for example, subscnption forms encountered m pre-pnnted publications They may, of course, also be generated on-the-fly by a netpage pnnter m response to user requests User-specific documents and forms are normally generated on the fly - 41 - by a netpage pπnter in response to user requests Figure 48 shows a genenc document 990, a genenc form 991, a user- specific document 992, and a user-specific form 993 Netpages which participate m a user mterface flow are further descπbed by abstract page layouts A page layout may contam vanous lands of elements, each of which has a umque style to differentiate it from the others As shown m Figure 49, these mclude fixed mformation 994, vanable information 995, mput fields 996, command buttons 997, and draggable commands 998 When a user mterface flow is broken up mto multiple diagrams, any document which is duplicated is shown with dashed outlines m all but the mam diagram which defines it 8.2 NOTE TAKING OBJECT MODEL The note taking object model revolves around a notebook and a netpage user The Note Takmg Object Model is represented by the class diagram of Figure 50 A netpage notebook 501 is created by a netpage user 800 Each notebook contams a set of pages 502 Each page has a page number, page content 504 consistmg of digital ink 873 (see Figure 33), and the text eqmvalent 505 of the digital ink Each notebook has a unique identifier, a user-assigned name, and a page style The digital mk making up the page content is timestamped by the system m the usual way as it is recorded The digital ink is also converted to text 505, usmg onlme handwntmg recogmtion, to allow text-based searches on notebook content Graphical searches can also be performed duectly on the digital ink (see below) The user may request that a notebook page 502 be digitally signed at any tune by a trusted entity 500, thereby certifymg the existence of the page content 504 at that tune A snapshot 506 of the page content 504 is taken, its creation tune is recorded, and the content and tune are signed by the trusted entity usmg its pnvate signature key, to produce the digital signature 507 The signed page content is recorded for future reference, mdexed by a umque reference number Anyone with access to the recorded signed page 503 can venfy its creation tune and content using the public signature key of the trusted entity 500 8.3 NOTE TAKING USER INTERFACE The user may obtam the Notebook Menu 508 from a vanety of links mcludmg the netpage user's own bookmark, and the help menu of the user's netpage pnnter The Notebook Menu user mterface flow is shown m Figure 51 From the Notebook Menu (Figure 53), the user may pnnt a list of all of theu notebooks, search for an entry m theu notebooks, or pπnt a new notebook Optionally, secunty can be added to notebooks by addmg signature venfication at key points A signature can be requued when reprinting a notebook, to venfy, for example, that the user is the owner of the notebook A signature can also be required before a user can search, and before a user can pnnt a new notebook 8.3.1 NEW NOTEBOOK From the Notebook Menu Page 508 shown m Figure 53, a user can pπnt a new netpage notebook on demand, m the style of theu choice When the user selects <New Notebook> from the Notebook Menu, a New Notebook order page 509 is pπnted, as shown m Figure 54 On the New Notebook order page 509 the user then specifies the notebook name, the number of pages to be mcluded m the notebook, and the page style Page styles mclude blank notebook pages, lmed pages, or pages pnnted with a 5mm or 10mm gnd When the user has specified theu preferences they click the <Pnnt Notebook> button The notebook is pπnted and bound on the user's netpage pnnter 8.3.2 MAKING NOTES Each notebook page 511 has the notebook name, user name, and page number along the top of the page, and buttons across the bottom of the page The rest of the page is the active notebook area for text and graphical mformation - 42 - A sample notebook page is shown m Figure 55 and the user mterface flow for the notebook page is shown m Figure 52 Notes wntten on the notebook with the user's netpage pen are stored on the network As the user wntes on the page, every pen sfroke is tune-stamped and stored with the time-stamp and any associated properties Handwntmg is recognized as it is wntten on the page, and converted to text to facilitate later searching, although this text version is generally not seen by the user as it is only used for the search functionality The pen strokes, or digital ink, can be used for graphical searches, as explained m further detail below The user can select content on the notebook page usmg the standard netpage selection mechanism, and can then paste this content to another netpage The user can pnnt a copy of the notebook page by clicking the <Repnnt> button Because every pen stroke of the page content is stored, the user can pnnt the page as it appeared at a specified tune If the user clicks the <Hιstory> button, a Page History page 515 is pπnted (not shown), on which the user can enter the date and tune for the page version they want A snapshot of the page at the specified tune is pπnted, with the date and tune appeanng at the top of the page The user is therefore able to review the changing content of a notebook The user can request a digital signature from a trusted entity for a notebook page by clicking the <Certify> button at the bottom of the notebook page The current page is reprinted with the current date and tune, the name of the trusted entity and a signature reference number 8.3.3 LIST NOTEBOOKS If the user clicks the <Lιst Notebooks> button on the Notebook Menu, a list of theu notebooks is pπnted, as shown m Figure 57 The Notebook List 510 shows the notebook name, the date of the first entry, and the date of the last entry for each notebook Clearly the system may allow other properties of notebooks to be additionally displayed if desued The user can reprint an entue notebook by clicking its <Repπnt Book> button 8.3.4 SEARCH If the user clicks the <Search> button on the Notebook Menu, a Notebook Search page 512 is pnnted, as shown m Figure 56 The user can enter as many or as few search cπtena as they want The user must enter either search text or a search picture All other fields are optional The user can specify the notebook name and/or page number to search The user can also limit the search to entnes made withm a specified date and/or tune range If the user wntes in the search text field on the form, the handwntmg is converted to text as it is bemg wntten The text of the user's notebooks is then searched for matching entnes Smce words recognised by the text converter may contam spelling errors, the system may provide a fuzzy search to enable retneval of words or phrases similar to the text searched The user may search for a picture by drawing the picture m the picture search field If <Match Any Sιze> is checked then the search matches pictures at any scale If <Match Any Sιze> is not checked and the picture is found within a scale of plus or minus 10% of that drawn, then it is considered a match If the user wishes to search for a picture that is larger than the form field they may draw a full size picture on the back of the page The graphical search is done duectly on the digital ink usmg appropnate digital ink matching methods, such as descnbed by Aref et al (Aref, W G , Kamel I , Lopresti, D P , "On Handlmg Elecfromc Ink", ACM Computing Surveys, Vol 27, No 4, December 1995), the entue content of which is mcluded herem by reference Picture search can also be used to search for text, which can be advantageous as it does not rely on text conversion of the ongmal notebook content Any user may wnte m a netpage notebook If someone other than the ongmal author does a graphical search, matching is typically less reliable because of handwπtmg differences between users The user may specify the number of matches to be returned by the search by checking the appropnate box at the bottom of the page - 43 - When all the known search cπteπa have been specified the user clicks the <Search> button The results are pπnted on one or more Search Results pages 513, shown m Figure 58 Each matchmg entry lists the notebook name, page number, and the date and tune the entry was made The match also shows a thumbnail unage of the page containing the match, with the matchmg entry highlighted by a red border, and an image of the area of the page matchmg the search term, l e showing the match m the context of its surroundings The user can pπnt the full page by clicking on either unage If the user limits the number of matches to be returned, but there are more matches available, the user can click the <Next> button to pnnt the next batch of matchmg entnes The user can click the <New Search> button to pnnt a blank Notebook Search form CONCLUSION Clearly, many alternative and additional features to those descnbed above are possible and will be evident to the skilled reader Whilst the mvention has been illustrated and descnbed m the context of a particular example thereof, it will be appreciated by the skilled reader that it may be implemented in other ways Furthermore, many modifications to the detailed features descnbed may be envisaged, and it is understood that any such modifications and/or additions to the embodiment specifically descnbed and illustrated herein may be made without departing from the spuit or scope of the mvention

Claims: - 44 - CLAIMS 1 A method of enablmg handwntten note taking and retneval, the method mcludmg the steps of providmg a user with at least one form printable on a surface, the form contammg information relatmg to a notebook activity and mcludmg coded data mdicative of an identity of the form and of at least one reference pomt of the form, receivmg, m a computer system, mdicatmg data from a sensmg device operated by said user, said mdicatmg data regardmg the identity of the form and a position of the sensmg device relative to the form, the sensmg device, when placed in an operative position relative to the form, sensing the mdicatmg data usmg at least some of the coded data, and identifymg in the computer system and from the mdicatmg data, at least one parameter relatmg to the notebook activity 2 The method of claim 1 m which said at least one parameter relatmg to the notebook activity is associated with at least one zone of said form, and m which the method mcludes identifying, m the computer system and from the zone relative to which the sensing device is located, said at least one parameter 3 The method of claun 2 which mcludes receivmg, in the computer system, data regardmg movement of the sensmg device relative to said form, the sensmg device sensmg its movement relative to said form, usmg at least some of the coded data, and identifymg, m the computer system and from said movement bemg at least partially withm said at least one zone, said at least one parameter of the notebook activity 4 A method of enablmg handwntten note takmg and retneval, the method mcludmg the steps of providmg a user with at least one form printable on a surface, said form containing mformation relatmg to a notebook activity and mcludmg coded data mdicative of at least one parameter of the notebook activity, receivmg, m a computer system, data from a sensmg device operated by said user regarding said at least one parameter and regardmg movement of the sensmg device relative to said form, the sensmg device, when moved relative to said form, sensmg the data regardmg said at least one parameter usmg at least some of the coded data and generatmg the data regardmg its own movement relative to said form, and interpreting, m the computer system, said movement of the sensmg device as it relates to said at least one parameter 5 A method of enablmg handwntten note takmg and retneval, the method mcludmg the steps of providmg a notebook user with a form mcludmg coded data mdicative of an identity of said form, receivmg, m a computer system, data from a sensmg device regardmg an identity of the user and regardmg the identity of said form, the sensmg device contammg the data regardmg the identity of the user and sensmg the data regardmg the identity of said form usmg at least some of the coded data, and identifymg, m the computer system and from the data regardmg the identity of the user and the identity of the form, a notebook activity 6 The method of claim 5 which mcludes receivmg, m the computer system, data from the sensmg device regardmg movement of the sensmg device relative to the form, the sensmg device generatmg data regarding its own movement relative to the form 7 The method of claim 2, 4 or 6, m which the parameter is an action parameter of the notebook activity, the method mcludmg effecting, m the computer system, an operation m respect of the action parameter 8 The method of claun 7, in which the action parameter of the notebook activity is selected from the group compnsmg listing a user's notebooks, - 45 - searchmg at least one of a user's notebooks, ordering a new notebook, pnntmg a new notebook, reprinting at least one notebook page, pnntmg certification copy of at least one notebook page, and pnntmg a representation of the history of at least one notebook page 9 The method of claim 2, 4 or 6 m which the parameter is an option parameter of the notebook activity, the method mcludmg identifymg, m the computer system, that the user has entered a hand-drawn mark by means of a sensmg device and effectmg, m the computer system, an operation associated with the option parameter 10 The method of claim 9 m which the option parameter is associated with at least one of a page style, and a search match return number 11 The method of claim 2, 4 or 6 m which the parameter is a text parameter of the notebook activity, the method including identifymg, m the computer system, that the user has entered handwntten text data by means of the sensmg device and effecting, m the computer system, an operation associated with the text parameter 12 The method of claun 11 which mcludes converting, m the computer system, the handwntten text data to computer text 13 The method of claim 11 m which the text parameter is associated with at least one of a user's name, a notebook name, a requued number of notebook pages, a page style, a notebook page number, a handwntten notebook entry, a certification signature, an item of search text, a notebook entry date, and a notebook entry tune 14 The method of claim 2, 4 or 6 m which the parameter is an authorization parameter of the notebook activity, the method mcludmg identifymg, m the computer system, that the user has entered a handwntten signature by means of the sensmg device and effectmg, m the computer system, an operation associated with the authorization parameter 15 The method of claim 14 which mcludes venfymg, m the computer system, that the signature is that of the user 16 The method of claim 14 which mcludes venfymg, m the computer system, that the signature is that of an authorized reader 17 The method of claim 14 m which the authorization parameter is associated with at least one of pnntmg a new notebook, searching at least one of a user's notebooks, and preprinting one or more notebook pages 18 The method of claim 2, 4 or 6 m which the parameter is a graphical parameter of the notebook activity, the method mcludmg identifymg, m the computer system, that the user has entered hand-drawn graphical - 46 - information by means of the sensmg device and effecting, m the computer system, an operation associated with the graphical parameter 19 The method of claim 18 m which the graphical parameter is associated with a hand drawn notebook entry 20 The method of claim 2, 4 or 6 m which at least one of the one or more forms contams information relatmg to at least one of a user's notebook menu, ordering a new notebook, a notebook name, a user name, a notebook page number, a certifymg entity for a notebook page, a notebook page reference number, a notebook search, a notebook list, and a notebook search result 21 The method of claun 2, 4 or 6, the surface bemg a paper page, the method mcludmg pnntmg the page on demand 22 The method of claim 21 which mcludes pnntmg the page and, at the same tune that the page is pnnted, pnntmg the coded data on the page 23 The method of claim 21 which includes pnntmg the coded data to be substantially invisible m the visible spectrum 24 The method of claim 2, 4 or 6 which mcludes retaining a retnevable record of each form generated, said form bemg retnevable usmg its identity as contained m its coded data 25 The method of claim 2, 4 or 6 m which said form is a notebook page, the method mcludmg retaining a retnevable record of a notebook page at a selected mstance m tune, said page bemg retnevable usmg its identity as contained m its coded data 26 The method of claun 2, 4 or 6 m which the sensmg device contams an identification means which imparts a umque identity to the sensmg device and identifies it as bemg associated with a particular user and m which the method mcludes momtonng, m the computer system, said identity 27 The method of claim 2, 4 or 6 which mcludes providmg all requued mformation relatmg to the notebook activity on the at least one form, to eliminate the need for a separate display device 28 The method of claim 2, 4 or 6 m which said form is provided on multiple pages and m which the method mcludes binding the pages 29 A system for enablmg handwntten note takmg and retneval, the system mcludmg at least one form printable on a surface, said form contammg information relatmg to a notebook activity and mcludmg coded data mdicative of an identity of said form and of at least one reference pomt of said form, and a computer system for receivmg mdicatmg data from a sensmg device operated by a user mvolved m the notebook activity, said mdicatmg data regardmg the identity of said form and a position of the sensmg device relative to said form, the sensmg device, when placed m an operative position relative to said form, sensmg the mdicatmg data usmg at least some of the coded data, said computer system mcludmg means for identifymg, from the - 47 - mdicatmg data, at least one parameter relatmg to the notebook activity 30 The system of claim 29 in which said at least one parameter relatmg to the notebook activity is associated with at least one zone of said form 31 The system of claim 29 mcludmg the sensmg device, the sensmg device sensmg its movement relative to said form, usmg at least some of the coded data 32 A system for enablmg handwritten note takmg and retneval, the system mcludmg at least one form printable on an mteractive surface, said form contammg information relatmg to a notebook activity and including coded data mdicative of at least one parameter of the notebook activity, and a computer system for receivmg data from a sensmg device operated by the notebook user, said data regardmg movement of the sensing device relative to said form, and for mterpretmg said movement of the sensmg device as it relates to said at least one parameter, the sensmg device, when moved relative to said form, sensmg the data regarding said at least one parameter usmg at least some of the coded data, and generatmg the data regardmg its own movement relative to said form 33 The system of claim 30 m which said at least one parameter relatmg to the notebook activity is associated with at least one zone of said form 34 The system of claim 32 mcludmg the sensmg device 35 A system for enablmg handwntten note takmg and retneval, the system mcludmg a form mcludmg coded data mdicative of an identity of the form, and a computer system for receivmg from a sensmg device data regardmg an identity of a notebook user and the identity of said form, and for identifymg, from said received data, a notebook activity, the sensmg device contammg the data regardmg the identity of the user and sensmg the data regardmg the identity of the form usmg at least some of the coded data 36 The svstem of claun 35 m which the coded data is also mdicative of at least one parameter of the notebook activity, the computer system receivmg mdicatmg data from the sensmg device regardmg said at least one parameter of the notebook activity, and the sensing device sensmg the mdicatmg data using at least some of the coded data 37 The system of claun 35 mcludmg a sensmg device, the sensmg device sensmg its movement relative to the form 38 The system of claun 29, 32 or 36 m which said at least one parameter of the notebook activity is selected from the group compπsmg an action parameter of the notebook activity, an option parameter of the notebook activity, a text parameter of the notebook activity, an authorization parameter of the notebook activity, and a graphical parameter of the notebook activity 39 The system of claun 38 m which the action parameter of the notebook activity is selected from the group compnsmg listing a user's notebooks, searching at least one of a user's notebooks, ordering a new notebook, pnntmg a new notebook, reprinting at least one notebook page, pnntmg certification copy of at least one notebook page, and pnntmg a representation of the history of at least one notebook page 40 The system of claun 38 m which the option parameter is associated with at least one of - 48 - a page style, and a search match retum number 41 The system of claun 38 m which the text parameter is associated with at least one of a user's name, a notebook name, a reqmred number of notebook pages, a page style, a notebook page number, a handwntten notebook entry, a certification signature, an item of search text, a notebook entry date, and a notebook entry tune 42 The system of claim 38 m which the authorization parameter is associated with at least one of pnntmg a new notebook, searching at least one of a user's notebooks, and preprinting one or more notebook pages 43 The system of claun 38 m which the graphical parameter is associated with a hand drawn notebook entry 44 The system of claim 29, 32 or 36 m which the sensmg device mcludes a marking mb 45 The system of claim 29, 32 or 36 m which the sensmg device contams an identification means which imparts a umque identity to the sensmg device and identifies it as bemg associated with a particular user 46 The system of claun 29, 32 or 36 m which the surface is a pnnted paper page, and m which the system mcludes a pπnter for pnntmg said foπn on the paper page on demand 47 The system of claun 46 m which the pπnter pπnts the coded data at the same time as pnntmg said form on the paper page 48 The system of claun 29, 32 or 36 m which the coded data is substantially invisible in the visible spectrum 49 The system of claim 29 or 35 which mcludes a database for keepmg a retnevable record of each form generated, each form bemg retnevable by usmg its identity as mcluded m its coded data 50 The system of claun 46 m which, to cater for a note takmg form prmted on multiple pages, the pπnter mcludes a binding means for binding the pages

Inventors: LAPSTUN JACQUELINE ANNE, LAPSTUN PAUL, LAPSTUN, JACQUELINE, ANNE, LAPSTUN, PAUL
Applicants: LAPSTUN JACQUELINE ANNE, LAPSTUN PAUL, SILVERBROOK KIA, SILVERBROOK RES PTY LTD, LAPSTUN, JACQUELINE, ANNE, LAPSTUN, PAUL, SILVERBROOK RESEARCH PTY LTD, SILVERBROOK, KIA
Application year: 2000
Main classification: G06F3
IPC codes: B41J2, B41J5, B41J13, B41J21, B41J29, B42C9, B42C19, B42D15, B65H29, B65H37, G06F3, G06F13, G06F17, G06F21, G06K9, G06K17, G06K19, G06Q10, G06Q30, G06Q50, G06T1, G06T11, G08C17, H04L9, H04N1