AU2003254771B2 - Method and system for capturing a note-taking session using processing sensor - Google Patents

Description

METHOD AND SYSTEM FOR CAPTURING A NOTE-TAKING SESSION USING PROCESSING

SENSOR

FIELD OF INVENTION The present invention relates generally to computing systems and, more particularly, to a method and system for capturing, in a computer system, data relating to a note-taking session. The system and method of the invention are suitable for use in, for example, an educational environment or a meeting environment.

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 invention: PCT/AU00/01442, PCT/AU00/01444, PCT/AU00/01446, PCT/AU00/01445, PCT/AU00/01450, PCT/AU00/01453, PCT/AU00/01448, PCT/AU00/01447, PCT/AUOO/01459, PCT/AU00/01451, PCT/AU00/01454, PCT/AU00/01452, PCT/AU00/01443, PCT/AU00/01455, PCT/AU00/01456, PCT/AUOO/01457, PCT/AU00/01458 and PCT/AUOO/01449.

The disclosures of these co-pending applications are incorporated herein by cross-reference 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 on 20 October 2000: PCT/AUOO/01273, PCT/AU00/01279, PCT/AUOO/01288, PCT/AU00/01282, PCT/AUOO/01276, PCT/AUOO/01280, PCT/AU00/01274, PCT/AU00/01289, PCT/AU00/01275, PCT/AUOO/01277, PCT/AUOO/01286, PCT/AU00/01281, PCT/AUOO/01278, PCT/AUO00/01287, PCT/AUOO/01285, PCT/AUOO/01284 and PCT/AU00/01283.

The disclosures of these co-pending applications are incorporated herein by cross-reference.

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 on 15 September 2000: PCT/AU00/01108, PCT/AU00/01110 and PCT/AU00/01111. The disclosures of these co-pending applications are incorporated herein by cross-reference.

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 on 30 June 2000: PCT/AU00/00762, PCT/AU00/00763, PCT/AU00/00761, PCT/AU00/00760, PCT/AU00/00759, PCT/AUOO/00758, PCT/AU00/00764, PCT/AU00/00765, PCT/AU00/00766, PCT/AU00/00767, PCT/AU00/00768, PCT/AU00/00773, PCT/AU00/00774, PCT/AU00/00775,PCT/AUOO/00776, NPA120AU PCT/AUOO/00777, PCT/AUOO/00770, PCT/AU0O/00769, PGT/AU00/0077 1, PCT/AUOO/00772, PCT/AUOO/00754, PCT/AU0O/00755, PCT/AU00/00756 and PCT/AUOO/00757.

The disclosures of these co-pending applications are incorporated herein by cross-reference.

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 on 24 May 2000: PCT/AUOO/005 18, PCT/AUOO/00523, PCT/AUOO/00528, PCT/AUOO/00533, PCT/AUOO/00538, PCT/AUOO/00543, PCTAUOOIOO554, PCT/AU0O/00560, PCT/AUOO/00565, PCT/AUOO/00570, PCT/AUOO/00575, PCT!AUOO/0058 1, PCT/AUOO/00589, PCT/AUOO/00592, PCT/AUOO/005 19, PCT/AUOO/00524, PCT/AUOO/00529, PCTIAUOO/00534, PCTAUOOIOO539, PCT/AUOO/00544, PCT/AUOO/00556, PCT/AUOO/0056 1, PCT/AUO0/00566, PCT/AUOO/0057 1, PCT/AUOO/00576, PCT/AUOO/00580, PCT/AUOO/00583, PCT/AUOO/00594, PCT/AUOO/00520, PCT/AUOO/00525, PCT/AUOO/00530, PCT/AUOO/00535, PCT/AUOO/00540, PCT/AUOO/00545, PCT/AUOO/00557, PCT/AUOO/00562, PCT/AUOO/00567, PCT/AUOO/00572, PCT/AUOO/00577, PCT/AUOO/00582, PCT/AUOO/00593, PCT/AUOO/00595, PCT/AUOO/0052 1, PCT/AUOO/00526, PCT/AUOO/0053 1, PCT/AUOO/00536, PCT/AUO0/0054 1, PCT/AUOO/00547, PCT/AUO0/00558, PCT/AUOO/00563, PCT/AU 00/00568, PCT/AUOO/005 73, PCT/AUOO/00578, PCT/AUOO/00587, PCT/AUOO/00590, PCT/AUOO/00596, PCTIAUO0522, PCTAUOOIOO527, PCT/AUOO/00532, PCT/AUOO/00537, PCT/AUOO/00542, PCT/AUOO/00546, PCT/AUOO/00559, PCT/AUOO/00564, PCT/AUOO/00569, PCT/AUOO/00574, PCT/AUOO/00579, PCT/AUOO/00588, PCT/AUOO/0059 1, PCT/AUOO/00597, PCT/AUOO/00598, PCT/AUOO/005 16, PCT/AUOO/005 17 and PCT/AUOO/005 1.

The disclosures of these co-pending applications are incorporated herein by cross-reference.

BACKGROUND

Remote whiteboard computer systems are already established. Such interactive systems allow participants in mutually disparate geographical locations to participate in a collaborative activity in real time.

Generally each participant has access to a computer means that is networked with the computers of the other participants. A display device accessible to each participant acts as a 'virtual whiteboard', allowing the participants to submit and receive drawings and alternative graphical or other information. Each participant may have a copy of a common drawing on his or her virtual whiteboard, and can edit or otherwise amend that drawing, such 'markups' being immediately transmitted to the other participants to maintain in a consistent state the common drawing.

Additionally, conventional whiteboards are also commonly used in educational environments, to facilitate the transfer of information from teacher to student, and in group discussions such as business meetings, where ideas need to be communicated between participants. The whiteboard provides a convenient surface on which concepts can be graphically expressed, by way of notes, drawings, charts, etc. Such notations can be made in selected colors and can be readily erased from the smooth, wipeable surface.

Electronic whiteboards which have been developed allow representations of notations made upon a NPA120AU specially designed whiteboard to be transmitted to a computer for storage, display, transmission, printing, etc.

During a meeting session, graphical user input entered on the electronic whiteboard is digitized and stored in a file, and dedicated whiteboard application software enables retrieval and manipulation. At any time, stored session files may be retrieved to view or print the information, or to copy it to other applications if required.

To this end, the whiteboard surface generally includes a writing/drawing region, and a control region providing means for inputting control commands via the whiteboard.

SUMMARY OF INVENTION It is an objective of the present invention to provide a new method and system for capturing, in a computer system, data relating to a note-taking session.

The present invention provides, in a first aspect, a method of capturing, in a computer system, data relating to a note-taking session, the session consisting of handwritten annotations made by a user by way of a writing implement on a plurality of pages, said pages including coded data indicative of at least one reference point of the page and the method including the steps of: receiving, in the computer system and via the writing implement, an indication of the start of the note-taking session; receiving, in the computer system and via the writing implement, data indicative of said handwritten annotations made by said user on said plurality of pages; receiving, in the computer system and via the writing implement, an indication of the end of the note-taking session; and retaining a retrievable record of the received data for the note-taking session, wherein the writing implement comprises: an image sensor adapted to capture images of at least some of the coded data when the writing implement is placed in an operative position relative to the page; and a processor adapted to: identify at least some of the coded data from one or more of the captured images; (ii) determine an orientation, within the captured images, of at least some of the coded data; (iii) decode at least some of the coded data; (iv) generate the data regarding said indication of at least one of the start and the end of the note-taking session using at least some of the decoded coded data; and generate the data indicative of said handwritten annotations using at least some of the decoded coded data.

According to the invention in a second aspect, there is provided a system for capturing data NPA120AU 3arelating to a note-taking session, the session consisting of handwritten annotations made by a user by way of a writing implement on a plurality of pages, said pages including coded data indicative of at least one reference point of the page the system including: a computer system for receiving indicating data via the writing implement operated by the user, said indicating data regarding a position and a movement of the writing implement relative to a page, the computer system including a start/end-identifier for identifying, from the indicating data, an indication of the start of the note-taking session and an indication of the end of the note-taking session; and a memory for retaining a retrievable record of the received data for the note-taking session, said retrievable record being indicative of said handwritten annotations made by said user on said plurality of pages between the start and end of the note-taking session, wherein the writing implement comprises: an image sensor adapted to capture images of at least some of the coded data when the writing implement is placed in an operative position relative to the page; and a processor adapted to: identify at least some of the coded data from one or more of the captured images; (ii) determine an orientation, within the captured images, of at least some of the coded data; (iii) decode at least some of the coded data; and (iv) generate the indicating data using at least some of the decoded coded data.

Accordingly, the present invention provides a system and a method which utilizes one or more forms capable of interacting with a computer system. Whilst the novel method and system of the present invention may be used in conjunction with a single computer system, it is also readily adapted to operate by means of a computer network, such as the Internet.

Physically, the form is disposed on a surface medium of any suitable structure. However, in a preferred arrangement, the form is disposed on sheet material such as paper or the like which has the coded NPA120AU data printed on it and which allows interaction with the computer system. The coded data is detectable preferably, but not exclusively, outside the visible spectrum, thereby enabling it to be machine-readable but substantially invisible to the human eye. The form may also include visible material which provides information to a user, such as the application or purpose of the form, and which visible information may be registered or correlate in position with the relevant hidden coded data.

The system also includes a sensing device to convey data from the form to the computer system, and in some instances, to contribute additional data. Again, the sensing device may take a variety of forms but is preferably compact and easily portable. In a particularly preferred arrangement, the sensing device is configured as a pen which is designed to be able to physically mark the interactive 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 interaction between the form and the sensing device and the data that each contributes to the computer system may vary. In one arrangement, the coded data on the form is indicative of the identity of the form and of at least one reference point on that form. In another embodiment, the interactive form includes coded data which is indicative of a parameter of the form, whereas the sensing device is operative to provide data regarding its own movement relative to that form to the computer system together with coded data from the form. In yet another arrangement, the form includes the coded data which at least identifies the form, and the sensing 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.

The system and method employs specially designed printers to print the interactive form. Further these printers constitute or form part of the computer system and are designed to receive data from the sensing device. As indicated above, the system and method of the invention is ideally suited to operate over a network. In this arrangement, the printers are fully integrated into the network and allow for printing of the interactive forms on demand and also for distributing of the forms using a mixture of multi-cast and point-cast communication protocols.

Accordingly, in a preferred form, the present invention provides methods and systems which use a paper and pen based interface 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, printed information is easier to read than information displayed on a computer screen. Moreover, paper does not run on batteries, can be read in bright light, or robustly accepts coffee spills or the like and is portable and disposable. Furthermore, the system allows for hand-drawing and hand-writing to be captured which affords greater richness of expression than input via a computer keyboard and mouse.

The present invention therefore provides a method and system for capturing, in a computer system, data relating to a note-taking session, making use of novel interactive surface media. It is to be understood in this specification and claims that the term 'note-taking session' refers to any session during which pages are annotated for presentation purposes. In particular, in carrying out the method of the invention, a notepad, (or NPA120AU 'whiteboard pad'), is employed to convey information.

Using the invention, participants can communicate graphical ideas on a whiteboard or similar, using interactive surface media. The whiteboard can take the form of a pad of large-format pre-printed pages supported for easy viewing on an easel. Multiple colored pens can be used during a whiteboard session, and the colors used can be reproduced on subsequently printed versions of the pages of a whiteboard session.

Each printed version of page can be timestamped and marked with the name of the author, if desired.

BRIEF DESCRIPTION OF DRAWINGS Preferred and other embodiments of the invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Figure 1 is a schematic of a the relationship between a sample printed netpage and its online page description; Figure 2 is a schematic view of a interaction between a netpage pen, a netpage printer, a netpage page server, and a netpage application server; Figure 3 is a schematic view of a high-level structure of a printed netpage and its online page description; Figure 4a is a plan view showing a structure of a netpage tag; Figure 4b is a plan view showing a relationship between a set of the tags shown in Figure 4a and a field of view of a netpage sensing device in the form of a netpage pen; Figure 5a is a plan view showing an alternative structure of a netpage tag; Figure 5b is a plan view showing a relationship between a set of the tags shown in Figure 5a and a field of view of a netpage sensing device in the form of a netpage pen; Figure 5c is a plan view showing an arrangement of nine of the tags shown in Figure 5a where targets are shared between adjacent tags; Figure 5d is a plan view showing the interleaving and rotation of the symbols of the four codewords of the tag shown in Figure Figure 6 is a schematic view of a set of user interface flow document icons; Figure 7 is a schematic view of a set of user interface page layout element icons; Figure 8 is a class diagram representing a conferencing system according to the invention; Figure 9 is an access type class diagram; Figure 10 illustrates the conferencing whiteboard page version numbering system; Figure 11 illustrates the conference session menu user interface flow; NPA120AU -6- Figure 12 illustrates the conference session list user interface flow; Figure 13 illustrates the book conference session user interface flow; Figure 14 illustrates the user interface flow for a whiteboard page; Figure 15 presents an overall illustration of the user interface flow for a conference session; Figure 16 shows the book a conference session page; Figure 17 shows the conference session control page; Figure 18 shows the session main page; Figure 19 shows a printed blank whiteboard page; Figure 20 shows the conference session end notice; Figure 21 shows the compose message page; Figure 22 is a class diagram representing a whiteboard pad and session; Figure 23 illustrates a whiteboard pad session user interface flow; Figure 24 shows a whiteboard pad page; Figure 25 shows a whiteboard session page; Figure 26 is a perspective view of a netpage pen and its associated tag-sensing field-of-view cone; Figure 27 is a perspective exploded view of the netpage pen shown in Figure 26; Figure 28 is a schematic block diagram of a pen controller for the netpage pen shown in Figures 26 and 27; Figure 29 is a schematic view of a pen class diagram; Figure 30 is a schematic view of a pen optical path; Figure 31 is a flowchart of a stroke capture algorithm; Figure 32 is a schematic view of a raw digital ink class diagram.

NPA120AU 6a- DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS Note: MemjetTM is a trademark of Silverbrook Research Pty Ltd, Australia.

In the preferred embodiment, the invention is configured to work with the netpage networked computer system, a summary of which is given below and a detailed description of which is given in our earlier applications, including in particular applications PCT/AU00/00569, PCT/AU00/00565, PCT/AU00/00561, PCT/AU00/00519 and PCT/AU00/00578. It will be appreciated that not every implementation will necessarily embody all or even most of the specific details and extensions described in these applications in relation to the basic system. However, the system is described in its most complete form to assist in understanding the context in which the preferred embodiments and aspects of the present invention operate.

In brief summary, the preferred form of the netpage system employs a computer interface in the form of a mapped surface, that is, a physical surface which contains references to a map of the surface NPA120AU maintained in a computer system. The map references can be queried by an appropriate sensing device.

Depending upon the specific implementation, the map references may be encoded visibly or invisibly, and defined in such a way that a local query on the mapped surface yields an unambiguous map reference both within the map and among different maps. The computer system can contain information about features on the mapped surface, and such information can be retrieved based on map references supplied by a sensing device used with the mapped surface. The information thus retrieved can take the form of actions which are initiated by the computer system on behalf of the operator in response to the operator's interaction with the surface features.

In its preferred form, the netpage system relies on the production of, and human interaction with, netpages. These are pages of text, graphics and images printed on ordinary paper or other media, but which work like interactive web pages. Information is encoded on each page using 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 information from the network or to signal preferences to a network server. In one embodiment, text written by hand on a netpage is automatically recognized and converted to computer text in the netpage system, allowing forms to be filled in. In other embodiments, signatures recorded on a netpage are automatically verified, allowing e-commerce transactions to be securely authorized.

As illustrated in Figure 1, a printed netpage 1 can represent a interactive form which can be filled in by the user both physically, on the printed page, and "electronically", via communication 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 printed using visible ink, and coded data 3 printed as a collection of tags 4 using invisible ink. The corresponding page description 5, stored on the netpage network, describes the individual elements of the netpage. In particular it describes the type and spatial extent (zone) of each interactive element text field or button in the example), to allow the netpage system to correctly interpret input via the netpage. The submit button 6, for example, has a zone 7 which corresponds to the spatial extent of the corresponding graphic 8.

As illustrated in Figure 2, the netpage pen 101, a preferred form of which is described in our earlier application PCT/AU00/00565, works in conjunction with a netpage printer 601, an Intemnet-connected printing appliance for home, office or mobile use. The pen is wireless and communicates securely with the netpage printer via a short-range radio link 9. The relevant description of PCT/AU00/00565 is reproduced below and in Figures 26-32.

The active sensing device of the netpage system is typically the pen 101, which, using its embedded controller 134, is able to capture and decode IR position tags from a page via an image sensor. The image sensor is a solid-state device provided with an appropriate filter to permit sensing at only near-infrared wavelengths. As described in more detail below, the system is able to sense when the nib is in contact with the surface, and the pen is able to sense tags at a sufficient rate to capture human handwriting e. at 200 dpi or NPA120AU greater and 100 Hz or faster). Information captured by the pen is encrypted and wirelessly transmitted to the printer (or base station), the printer or base station interpreting the data with respect to the (known) page structure.

The preferred embodiment of the netpage pen operates both as a normal marking ink pen and as a non-marking stylus. The marking aspect, however, is not necessary for using the netpage system as a browsing system, such as when it is used as an Internet interface. Each netpage pen is registered with the netpage system and has a unique pen ID 61.

Figure 29 shows the netpage pen class diagram, reflecting pen-related information maintained by a registration server 11 on the netpage network.

When either nib is in contact with a netpage, the pen determines its position and orientation relative to the page. The nib is attached to a force sensor, and the force on the nib is interpreted relative to a threshold to indicate whether the pen is "up" or "down". This allows a interactive element on the page to be 'clicked' by pressing with the pen nib, in order to request, say, information from a network. Furthermore, the force is captured as a continuous value to allow, say, the full dynamics of a signature to be verified.

The pen determines the position and orientation of its nib on the netpage by imaging, in the infrared spectrum, an area 193 of the page in the vicinity of the nib. 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 below, because the tag density on the page is inversely proportional to the tag size, the adjusted position resolution is quite high, exceeding the minimum resolution required for accurate handwriting recognition.

Pen actions relative to a netpage are captured as a series of strokes. A stroke consists of a sequence of time 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 ID changes, which, under normal circumstances, is at the commencement of the stroke.

Each netpage pen has a current selection 826 associated with it, allowing the user to perform copy and paste operations etc. The selection is time stamped to allow the system to discard it after a defined time period. The current selection describes a region of a page instance. It consists of the most recent digital ink stroke captured through the pen relative to the background area of the page. It is interpreted in an applicationspecific manner once it is submitted to an application via a selection hyperlink activation.

Each pen has a current nib 824. This is the nib last notified by the pen to the system. In the case of the default netpage pen described above, either the marking black ink nib or the non-marking stylus nib is current. Each pen also has a current nib style 825. This is the nib style last associated with the pen by an application, e. g. in response to the user selecting a color from a palette. The default nib style is the nib style associated with the current nib. Strokes captured through a pen are tagged with the current nib style. When the strokes are subsequently reproduced, they are reproduced in the nib style with which they are tagged.

Whenever the pen is within range of a printer with which it can communicate, the pen slowly NPA120AU 7b flashes its "online" LED. When the pen fails to decode a stroke relative to the page, it momentarily activates its "error" LED. When the pen succeeds in decoding a stroke relative to the page, it momentarily 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 handwriting, for online recognition of handwriting, and for online verification of signatures.

The pen is wireless and transmits digital ink to the netpage printer via a short-range radio link. The transmitted digital ink is encrypted for privacy and security and packetized for efficient transmission, but is always flushed on a pen-up event to ensure timely handling in the printer.

When the pen is out-of-range of a printer it buffers digital ink in internal memory, which has a capacity of over ten minutes of continuous handwriting. When the pen is once again within range of a printer, it transfers any buffered digital ink.

A pen can be registered with any number of printers, but because all state data resides in netpages both on paper and on the network, it is largely immaterial which printer a pen is communicating with at any particular time.

Referring to Figures 26 and 27, the pen, generally designated by reference numeral 101, includes a housing 102 in the form of a plastics moulding having walls 103 defining an interior space 104 for mounting the pen components. The pen top 105 is in operation rotatably mounted at one end 106 of the housing 102. A semi-transparent cover 107 is secured to the opposite end 108 of the housing 102. The cover 107 is also of moulded plastics, and is formed from semitransparent material in order to enable the user to view the status of the LED mounted within the housing 102. The cover 107 includes a main part 109 which substantially surrounds the end 108 of the housing 102 and a projecting portion 110 which projects back from the main part 109 and fits within a corresponding slot 111 formed in the walls 103 of the housing 102. A radio antenna 112 is mounted behind the projecting portion 110, within the housing 102. Screw threads 113 surrounding an aperture 113A on the cover 107 are arranged to receive a metal end piece 114, including corresponding screw threads 115. The metal end piece 114 is removable to enable ink cartridge replacement.

Also mounted within the cover 107 is a tri-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 marking ink pen and as a non-marking stylus. An ink pen cartridge 118 with nib 119 and a stylus 120 with stylus nib 121 are mounted side by side within the housing 102. Either the ink cartridge nib 119 or the stylus nib 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 cartridge 118 and stylus 120, respectively. A rotatable cam barrel 125 is secured to the pen top 105 in operation and arranged to rotate therewith. The cam barrel 125 includes a cam 126 in the form of a slot within the walls 181 of the cam barrel. Cam followers 127 and 128 projecting from slider blocks 123 and 124 fit NPA120AU 7c 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 nib 119 or stylus nib 121 out through the hole 122 in the metal end piece 114.

The pen 101 has three states of operation. By turning the top 105 through 90 degree steps, the three states are: Stylus 120 nib 121 out; Ink cartridge 118 nib 119 out; and Neither ink cartridge 118 nib 119 out nor stylus 120 nib 121 out.

A second flex PCB 129, is mounted on an electronics chassis 130 which sits within the housing 102. The second flex PCB 129 mounts an infrared LED 131 for providing infrared radiation for projection onto the surface. An image 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 includes an RF transmitter and RF receiver, and a controller chip 134 for controlling 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 within 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 in contact with the battery contacts. An induction charging coil 140 is mounted about the second flex PCB 129 to enable recharging of the battery 139 via induction. The second flex PCB 129 also mounts an infrared LED 143 and infrared photodiode 144 for detecting displacement in the cam barrel 125 when either the stylus 120 or the ink cartridge 118 is used for writing, in order to enable a determination of the force being applied to the surface by the pen nib 119 or stylus nib 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 grip pads 141 and 142 are provided towards the end 108 of the housing 102 to assist gripping the pen 101, and top 105 also includes a clip 142 for clipping the pen 101 to a pocket.

The pen 101 is arranged to determine the position of its nib (stylus nib 121 or ink cartridge nib 119) by imaging, in the infrared spectrum, an area of the surface in the vicinity of the nib. It records the location data from the nearest location tag, and is arranged to calculate the distance of the nib 121 or 119 from the location tab utilising optics 135 and controller chip 134. The controller chip 134 calculates the orientation of the pen and the nib-to-tag distance from the perspective distortion observed on the imaged tag.

Control data from the location tag may include control bits instructing the pen 101 to activate its "active area" LED (this is in fact one mode of the tri-color LED 116, which becomes yellow when the pen determines, from the control data, that the area that is being imaged is an "active area"). Thus, a region on the surface which corresponds to the active area of a button or hyperlink may be encoded to activate this LED, giving the user of the pen visual feedback that the button or hyperlink is active when the pen 101 passes over it. Control data may also instruct the pen 101 to capture continuous pen force readings. Thus a region on the surface which corresponds to a signature input area can be encoded to capture continuous pen 101 force.

NPA120AU 7d Pen 101 action relative to the surface may comprise a series of strokes. A stroke consists of a sequence of time-stamped pen 101 positions on the surface, initiated by pen-down event and completed by a subsequent pen-up event. Note that pen force can be interpreted relative to a threshold to indicate whether the pen is "up" or "down", as well as being interpreted as a continuous value, for example when the pen is capturing a signature. The sequence of captured strokes constitutes so-called "digital ink". Digital ink can be used with a computing system to form the basis for the digital exchange of drawings and handwriting, for online recognition of handwriting, and for on-line verification of signatures.

Utilising the RF chip 133 and antenna 112 the pen 101 can transmit the digital ink data (which is encrypted for security 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 within the pen 101 (the pen 101 circuitry includes a buffer arranged to store digital ink 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 28 is a block diagram illustrating in more detail the architecture of the controller chip 134. Figure 28 also shows representations of the RF chip 133, the image sensor 132, the tri-color status LED 116, the IR illumination LED 131, the IR force sensor LED 143, and the force sensor photodiode 144.

The pen controller chip 134 includes a controlling 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 included. An analog-to-digital converter 149 is arranged to convert the analog signal from the force sensor photodiode 144 to a digital signal.

An image sensor interface 152 interfaces with the image sensor 132. A transceiver controller 153 and base band circuit 154 are also included to interface with the RF chip 133 which includes an RF circuit 155 and RF resonators and inductors 156 connected to the antenna 112.

The controlling processor 145 captures and decodes location data from tags from the surface via the image sensor 132, monitors the force sensor photodiode 144, controls the LEDs 116, 131 and 143, and handles short-range radio communication via the radio transceiver 153. It is a medium-performance (approx general-purpose RISC processor.

The processor 145, digital transceiver components (transceiver controller 153 and baseband circuit 154), image sensor interface 152, flash memory 147 and 512KB DRAM 148 are integrated in a single controller ASIC. Analog RF components (RF circuit 155 and RF resonators and inductors 156) are provided in the separate RF chip.

The image sensor is a 215x215 pixel CCD (such a sensor is produced by Matsushita Electronic Corporation, and is described in a paper by Itakura, K T Nobusada, N Okusenya, R Nagayoshi, and M Ozaki, "A lmm 50k-Pixel IT CCD Image Sensor for Miniature Camera System", IEEE Transactions on Electronic Devices, Volt 47, numberl, January 2000, which is incorporated herein by reference) with an IR filter.

NPA120AU 7e The controller ASIC 134 enters a quiescent state after a period of inactivity when the pen 101 is not in contact with a surface. It incorporates a dedicated circuit 150 which monitors the force sensor photodiode 144 and wakes up the controller 134 via the power manager 151 on a pen-down event.

The radio transceiver communicates in the unlicensed 900MHz band normally used by cordless telephones, or alternatively in the unlicensed 2.4GHz industrial, scientific and medical (ISM) band, and uses frequency hopping and collision detection to provide interference-free communication.

As discussed above, the pen 101 optics is implemented by a moulded optics body 135. The optics that is implemented by the optics body 135 is illustrated schematically in Figure 30. The optics comprises a first lens 157 for focusing radiation from the infrared LED 131, a mirror 158, a beam splitter 159, an objective lens 160 and a second lens 161 for focusing an image onto image sensor 132. Axial rays 162 illustrate the optical path.

The optical path is designed to deliver a sharp image to the image sensor 132 of that part 193 of the imaged surface which intersects the field of view cone 192, within required tilt ranges (see later). The primary focusing element is the objective lens 160. This is also used in reverse to project illumination from the IR illumination LED 131 onto the surface within the field of view. Since it is impractical to place both the image sensor 132 and the IR LED 131 at the focus of the objective, a beam splitter 159 is used to split the path and separate relay lenses 157 and 161 in each path provides refocusing at the image sensor 132 and the IR LED 131 respectively. This also allows different apertures to be imposed on the two paths.

The edges of the image sensor 132 act as the field stop for the capture field, and the capture path is designed so that the resulting object space angular field of view is as required just under 20 for the application of this embodiment). The illumination path is designed to produce the same object space field of view as the capture path, so that the illumination fills the object space field of view with maximum power and uniformity.

The IR LED 131 is strobed in synchrony with frame capture. The use of focused illumination allows both a short exposure time and a small aperture. The short exposure time prevents motion blur, thus allowing position tag data capture during pen movement. The small aperture allows sufficient depth of field for the full range of surface depths induced by tilt. The capture path includes an explicit aperture stop 191 for this purpose.

Because the image sensor 132 has a strong response throughout the visible and near infrared part of the spectrum, it is preceded by an infrared filter 163 in the capture path so that it captures a clean image of the tag data on the surface, free from interference from other graphics on the surface which may be printed using inks which are transparent in the near infrared.

When the stylus nib 121 or ink cartridge nib 119 of the pen 101 is in contact with a surface, the pen 101 determines its position and orientation relative to the surface at 100 Hz to allow accurate handwriting recognition (see the article by Tappert, C, C Y Suen and T Wakahara, "The State of the Art in On-Line Hand Writing Recognition "IEEE Transactions on Patent Analysis and Machine Intelligence, Vol 12, number 8, NPA120AU August 1990, the disclosure of which is incorporated herein by cross-reference). The force sensor photodiode 144 is utilised to indicate relative threshold whether the pen is "up" or "down". The force may also be captured as a continuous value, as discussed above, to allow the full dynamics of a signature to be verified.

The pen 101 determines the position and orientation of its nib 119,121 on the surface by imaging, in the infrared spectrum, an area of the surface in the vicinity of the nib 119,121. It decodes the nearest tag data and computes the position of the nib 119,121 relative to the location tag from the observed perspective distortion on the imaged tag and the known geometry of the pen optics 135 (see later). Although the position resolution of the tag may be low, the adjusted position resolution is quite high, and easily exceeds the 200 dpi resolution required for accurate handwriting recognition (see above reference).

Pen 101 actions relative to a surface are captured as a series of strokes. A stroke consists of a sequence of time-stamped pen positions on the surface, initiated by a pen-down event and completed by the subsequent pen-up event.

A stroke is also tagged with the region ID of the surface whenever the region ID changes, i.e. just at the start of the stroke under normal circumstances. As discussed above, each location tag includes data indicative of its position on the surface and also region data indicative of the region of the surface within which the tag lies.

Figure 32 is a diagram illustrating location tag and stroke processing in the pen 101. When the pen 101 is in the pen-up state, the pen controller 134 continuously monitors the force sensor When the pen 101 connects to the computing system, the controller 134 notifies the system of the pen ID, nib ID 175, current absolute time 176, and the last absolute time it obtained from the system prior to going offline. This allows the system to compute any drift in the pen's clock and timeshift any digital ink received from the pen 101 accordingly. The pen 101 then synchronises its real-time clock with the accurate real-time clock of the system. The pen ID allows the computing system to identify the pen when there is more than one pen being operated with the computing system. Pen ID may be important in systems which use the pen to identify an owner of the pen, for example, and interact with that owner in a particular directed manner.

In other embodiments this may not be required. The nib ID allows the computing system to identify which nib, stylus nib 121 or ink cartridge nib 119, is presently being used. The computing system can vary its operation depending upon which nib is being used. For example, if the ink cartridge nib 119 is being used the computing system may defer producing feedback output because immediate feedback is provided by the ink markings made on the surface. Where the stylus nib 121 is being used, the computing system may produce immediate feedback output.

At the start of a stroke the pen controller 134 records the elapsed time since the last absolute time notified to the system. For each pen 101 position 177, in the stroke the controller 134 records the x and y offset of the pen nib 119, 121 from the current tag, the x, y and z rotation of the pen 101, and the nib force. It only records the tag ID 178 (data identifying tag location) if it has changed. Since the tag frequency is significantly smaller than the typical position sampling frequency, the tag ID is constant for many consecutive pen 101 positions, and may be constant for the entire stroke if the stroke is short.

NPA120AU 7g Since the pen 101 samples its positions and orientation at 100 Hz, pen 101 positions in a stroke are implicitly clocked at 100 Hz and do not need an explicit timestamp. If the pen 101 fails to compute a pen 101 position, e.g. because it fails to decode a tag, it must still record a pen 101 position to preserve the implicit clocking. It therefore records the position as unknown, 179 allowing the computing system to later interpolate the position from adjacent samples if necessary.

Since the 32-bit time offset of a stroke has a finite range e. 49.7 days), the pen 101 optionally records an absolute time 176 for a stroke. This becomes the absolute time relative to which later strokes' time offsets are measured. Since the region ID is constant for many consecutive strokes, the pen only records the region ID when it changes 180. This becomes the region ID implicitly associated with later pen positions.

Since a user may change the nib 119,121 between one stroke and the next, the pen 101 optionally records a nib ID for a stroke 175. This becomes the nib ID implicitly associated with later strokes.

A 10mm stroke of 1 second duration spans two or three tags, contains 100 positions samples, and therefore has a size of about 5500 bits. Online continuous digital ink capture therefore requires a maximum transmission speed of 5.5 Kbps, and offline continuous digital ink capture requires about 40 Kbytes of buffer memory per minute. The pen's 512KB DRAM 48 can therefore hold over 12 minutes of continuous digital ink.

Time, region and nib changes happen so infrequently that they have a negligible effect on the required transmission speed and buffer memory. Additional compression of pen 101 positions can reduce transmission speed and buffer memory requirements further.

Each raw stroke is encrypted using the Triple-DES algorithm (Schneier, B, Applied Cryptography, Second Edition, Wiley 1996, the disclosure of which is incorporated herein by cross-reference) before being transmitted to the computing system. The pen and computing system exchange session keys for this purpose on a regular basis. Based on a conservative estimate of 50 cycles per encrypted bit, the encryption of a onesecond 5500 bit stroke consumes 0.7% of the processor's 45 time.

In an alternative embodiment, the pen incorporates an Infrared Data Association (IrDA) interface for short range communication with a base station or netpage printer.

In a further embodiment, the pen 101 includes a pair of orthogonal accelerometers mounted in the normal plane of the pen 101 axis. The accelerometers 190 are shown in Figures 28 and 29 in ghost outline.

The provision of the accelerometers enables this embodiment of the pen 101 to sense motion without reference to surface location tags, allowing the location tags to be sampled at a lower rate. Each location tag TD can then identify an object of interest rather than a position on the surface. For example, if the object is a user interface input element g. a command button), then the tag ID of each location tag within the area of the input element can directly identify the input element.

The acceleration measured by the accelerometers in each of the x and y directions is integrated with respect to time to produce an instantaneous velocity and position.

Since the starting position of the stroke is not known, only relative positions within a stroke are calculated.

NPA120AU 7h Although position integration accumulates errors in the sensed acceleration, accelerometers typically have high resolution, and the time duration of a stroke, over which errors accumulate, is short.

The netpage printer 601, preferred forms of which are described in our earlier application PCT/AU00/00561 and our co-filed application PCT/AU00/1281, is able to deliver, periodically or on demand, personalized newspapers, magazines, catalogs, brochures and other publications, all printed at high quality as interactive netpages. Unlike a personal computer, the netpage printer is an appliance which can be, for example, wall-mounted adjacent to an area where the morning news is first consumed, such as in a user's kitchen, near a breakfast table, or near the household's point of departure for the day. It also comes in NPA120AU tabletop, desktop, portable and miniature versions.

Netpages printed at their point of consumption combine the ease-of-use of paper with the timeliness and interactivity of an interactive medium.

As shown in Figure 2, the netpage pen 101 interacts with the coded data on a printed netpage 1 and communicates, via a short-range radio link 9, the interaction to a netpage printer. The printer 601 sends the interaction to the relevant netpage page server 10 for interpretation. In appropriate circumstances, the page server sends a corresponding message to application computer software running on a netpage application server 13. The application server may in turn send a response which is printed on the originating printer.

The netpage system is made considerably more convenient in the preferred embodiment by being used in conjunction with high-speed microelectromechanical system (MEMS) based inkjet (Memjet

TM

printers, for example as described in our earlier application PCT/AU00/00578. In the preferred form of this technology, relatively high-speed and high-quality printing is made more affordable to consumers. In its preferred form, a netpage publication has the physical characteristics of a traditional newsmagazine, such as a set of letter-size glossy pages printed in full color on both sides, bound together for easy navigation and comfortable handling.

The netpage printer exploits the growing availability of broadband Internet access. The netpage printer can also operate with slower connections, but with longer delivery times and lower image quality. The netpage system can also be enabled using existing consumer inkjet and laser printers, although the system will operate more slowly and will therefore be less acceptable from a consumer's point of view. In other embodiments, the netpage system is hosted on a private intranet. In still other embodiments, the netpage system is hosted on a single computer or computer-enabled device, such as a printer.

Netpage publication servers 14 on the netpage network are configured to deliver print-quality publications to netpage printers. Periodical publications are delivered automatically to subscribing netpage printers via pointcasting and multicasting Internet protocols. Personalized publications are filtered and formatted according to individual user profiles.

A netpage printer can be configured to support any number of pens, and a pen can work with any number of netpage printers. In the preferred implementation, each netpage pen has a unique identifier. A household may have a collection of colored netpage pens, one assigned to each member of the family. This allows each user to maintain 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 using the netpage pen. The netpage registration server compares the signature captured by the netpage pen with a previously registered signature, allowing it to authenticate the user's identity to an e-commerce server. Other biometrics can also be used to verify identity. A version of the netpage pen includes fingerprint scanning, verified in a similar way by the netpage registration server.

NPA120AU Although a netpage printer may deliver periodicals such as the morning newspaper without user intervention, it can be configured never to deliver unsolicited junk mail. In its preferred form, it only delivers periodicals from subscribed or otherwise authorized sources. In this respect, the netpage printer is unlike a fax machine or e-mail account which is visible to any junk mailer who knows the telephone number or e-mail address.

Each object model in the system is described using a Unified Modeling Language (UML) class diagram. A class diagram consists of a set of object classes connected by relationships, and two kinds of relationships are of interest here: associations and generalizations. An association represents some kind of relationship between objects, i.e. between instances of classes. A generalization relates actual classes, and can be understood in the following 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. Each class is drawn as a rectangle labelled with the name of the class. It contains a list of the attributes of the class, separated from the name by a horizontal line, and a list of the operations of the class, separated from the attribute list by a horizontal line. In the class diagrams which follow, however, operations are never modelled. An association is drawn as a line joining two classes, optionally labelled at either end with the multiplicity of the association. The default multiplicity is one.

An asterisk indicates 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 indicates an aggregation association ("is-part-of'), and is drawn at the aggregator end of the association line. A generalization relationship is drawn as a solid line joining two classes, with an arrow (in the form of an open triangle) at the generalization end. When a class diagram is broken up into multiple diagrams, any class which is duplicated is shown with a dashed outline in all but the main diagram which defines it. It is shown with attributes only where it is defined.

Netpages are the foundation on which a netpage network is built. They provide a paper-based user interface to published information and interactive services. A netpage consists of a printed page (or other surface region) invisibly tagged with references to an online description of the page. The online page description is maintained persistently by a netpage page server. The page description describes the visible layout and content of the page, including text, graphics and images. It also describes the input elements on the page, including buttons, hyperlinks, and input 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 description. However, to allow input through otherwise identical pages to be distinguished, each netpage is assigned a unique page identifier. This page ID has sufficient precision to distinguish between a very large number of netpages.

Each reference to the page description is encoded in a printed tag. The tag identifies the unique page on which it appears, and thereby indirectly identifies the page description. The tag also identifies its own position on the page. Characteristics of the tags are described in more detail below.

Tags are printed in 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 NPA image sensor with an appropriate filter.

A tag is sensed by an area image sensor in the netpage pen, and the tag data is transmitted to the netpage system via the nearest netpage printer. The pen is wireless and communicates with the netpage printer 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 single click on the page. It is important that the pen recognize the page ID and position on every interaction with the page, since the interaction is stateless. Tags are error-correctably encoded to make them partially tolerant to surface damage.

The netpage page server maintains a unique page instance for each printed netpage, allowing it to maintain a distinct set of user-supplied values for input fields in the page description for each printed netpage.

The relationship between the page description, the page instance, and the printed netpage is shown in Figure 3. The printed netpage may be part of a printed netpage document 45. The page instance is associated with both the netpage printer which printed it and, if known, the netpage user who requested it.

In a preferred form, each tag identifies the region in which it appears, and the location of that tag within the region. A tag may also contain 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 indicative of a function associated with the immediate area of the tag, without the sensing device having to refer to a description of the region. A netpage pen may, for example, illuminate an "active area" LED when in the zone ofa hyperlink.

In a preferred embodiment, each tag contains an easily recognized invariant structure which aids initial detection, and which assists in minimizing the effect of any warp induced by the surface or by the sensing process. The tags preferably tile the entire page, and are sufficiently small and densely arranged that the pen can reliably image at least one tag even on a single click on the page. It is important that the pen recognize the page ID and position on every interaction with the page, since the interaction is stateless.

In a preferred embodiment, the region to which a tag refers coincides with an entire page, and the region ID encoded in 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 coincide with the zone of an interactive element, in which case the region ID can directly identify the interactive element.

Each tag contains typically contains 16 bits of tag ID, at least 90 bits of region ID, and a number of flag bits. Assuming a maximum tag density of 64 per square inch, a 16-bit tag ID supports a region size of up to 1024 square inches. Larger regions can be mapped continuously without increasing the tag ID precision simply by using abutting regions and maps. The distinction between a region ID and a tag ID is mostly one of convenience. For most purposes the concatenation of the two can be considered as a globally unique tag ID.

Conversely, it may also be convenient to introduce structure into the tag ID, for example to define the x and y coordinates of the tag. A 90-bit region ID allows 2 90 (_1027 or a thousand trillion trillion) different regions to be uniquely identified. Tags may also contain type information, and a region may be tagged with a mixture of tag types. For example, a region may be tagged with one set of tags encoding x coordinates and another set, NPA120AU

L

-11interleaved with the first, encoding y coordinates.

In one embodiment, 120 bits of tag data are redundantly encoded using 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, i.e. it is tolerant of a symbol error rate of up to 33% per codeword. Each 4-bit symbol is represented in a spatially coherent way in the tag, and the symbols of the six codewords are interleaved spatially within the tag. This ensures that a burst error (an error affecting multiple spatially adjacent bits) damages a minimum number of symbols overall and a minimum number of symbols in any one codeword, thus maximising the likelihood that the burst error can be fully corrected.

Any suitable error-correcting code code can be used in place of a (15, 5) Reed-Solomon code, for example a Reed-Solomon code with more or less redundancy, with the same or different symbol and codeword sizes; another block code; or a different kind of code, such as a convolutional code (see, for example, Stephen B. Wicker, Error Control Systems for Digital Communication and Storage, Prentice-Hall 1995, the contents of which a herein incorporated by cross-reference).

One embodiment of the physical representation of the tag, shown in Figure 4a and described in our earlier application PCT/AUO0/00569, includes fixed target structures 15, 16, 17 and variable data areas 18.

The fixed target structures allow a sensing device such as the netpage pen to detect the tag and infer its threedimensional orientation relative to the sensor. The data areas contain representations of the individual bits of the encoded tag data. To maximise its size, each data bit is represented by a radial wedge in the form of an area bounded by two radial lines and two concentric circular arcs. Each wedge has a minimum dimension of 8 dots at 1600 dpi and is designed so that its base (its inner arc), is at least equal to this minimum dimension.

The height of the wedge in the radial direction is always equal to the minimum dimension. Each 4-bit data symbol is represented by an array of 2x2 wedges. The fifteen 4-bit data symbols of each of the six codewords are allocated to the four concentric symbol rings 18a to 18d in interleaved fashion. Symbols are allocated alternately in 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" interaction with a tagged region via a sensing device, the sensing device must be able to see at least one entire tag in its field of view no matter where in the region or at what orientation it is positioned. The required diameter of the field of view of the sensing device is therefore a function of the size and spacing of the tags. Assuming a circular tag shape, the minimum diameter of the sensor field of view 193 is obtained when the tags are tiled on a equilateral triangular grid, as shown in Figure 4b.

The tag structure just described is designed to allow both regular tilings of planar surfaces and irregular tilings of non-planar surfaces. Regular tilings are not, in general, possible on non-planar surfaces. In the more usual case of planar surfaces where regular tilings of tags are possible, i.e. surfaces such as sheets of paper and the like, more efficient tag structures can be used which exploit the regular nature of the tiling.

An alternative tag structure more suited to a regular tiling is shown in Figure 5a. The tag 4 is square and has four perspective targets 17. It is similar in structure to tags described by Bennett et al. in US NPA120AU I

I

-12- Patent 5,051,746. The tag represents sixty 4-bit Reed-Solomon symbols 47, for a total of 240 bits. The tag represents each one bit as a dot 48, and each zero bit by the absence of the corresponding dot. The perspective targets are designed to be shared between adjacent tags, as shown in Figures 5b and 5c. Figure 5b shows a square tiling of 16 tags and the corresponding minimum field of view 193, which must span the diagonals of two tags. Figure 5c shows a square tiling of nine tags, containing all one bits for illustration purposes.

Using a (15, 7) Reed-Solomon code, 112 bits of tag data are redundantly encoded to produce 240 encoded bits. The four codewords are interleaved spatially within the tag to maximize resilience to burst errors. Assuming a 16-bit tag ID as before, this allows a region ID of up to 92 bits. The data-bearing dots 48 of the tag are designed to not overlap their neighbors, so that groups of tags cannot produce structures which resemble targets. This also saves ink. The perspective targets therefore allow detection of the tag, so further targets are not required.

Although the tag may contain an orientation feature to allow disambiguation of the four possible orientations of the tag relative to the sensor, it is also possible to embed orientation data in the tag data. For example, the four codewords can be arranged so that each tag orientation contains one codeword placed at that orientation, as shown in Figure 5d, where each symbol is labelled with the number of its codeword and the position of the symbol within the codeword Tag decoding then consists of decoding one codeword at each orientation. Each codeword can either contain a single bit indicating whether it is the first codeword, or two bits indicating which codeword it is. The latter approach has the advantage that if, say, the data content of only one codeword is required, then at most two codewords need to be decoded to obtain the desired data.

This may be the case if the region ID is not expected to change within a stroke and is thus only decoded at the start of a stroke. Within a stroke only the codeword containing the tag ID is then desired. Furthermore, since the rotation of the sensing device changes slowly and predictably within a stroke, only one codeword typically needs to be decoded per frame.

It is possible to dispense with perspective targets altogether and instead rely on the data representation being self-registering. In this case each bit value (or multi-bit value) is typically represented by an explicit glyph, i.e. no bit value is represented by the absence of a glyph. This ensures that the data grid is well-populated, and thus allows the grid to be reliably identified and its perspective distortion detected and subsequently corrected during data sampling. To allow tag boundaries to be detected, each tag data must contain a marker pattern, and these must be redundantly encoded to allow reliable detection. The overhead of such marker patterns is similar to the overhead of explicit perspective targets. One such scheme uses dots positioned a various points relative to grid vertices to represent different glyphs and hence different multi-bit values (see Anoto Technology Description, Anoto April 2000).

Decoding a tag results in 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 into an absolute location within the tagged region, the location of the tag within the region must be known. This is given by a tag map, a function which maps each tag ID in a tagged region to a corresponding location. 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 NPA120AU -13 tiling scheme and the same tag numbering scheme, they can also share the same tag map. The tag map for a region must be retrievable via the region ID. Thus, given a region ID, a tag ID and a pen transform, the tag map can be retrieved, the tag ID can be translated into an absolute tag location within the region, and the tagrelative pen location can be added to the tag location to yield an absolute pen location within the region.

The tag ID may have a structure which assists translation through the tag map. It may, for example, encoded cartesian coordinates or polar coordinates, depending on the surface type on which it appears. The tag ID structure is dictated by and known to the tag map, and tag IDs associated with different tag maps may therefore have different structures.

Two distinct surface coding schemes are of interest, both of which use the tag structure described 1 0 earlier in this section. The preferred coding scheme uses "location-indicating" tags as already discussed. An alternative coding scheme uses "object-indicating" (or "function-indicating") tags.

A location-indicating tag contains a tag ID which, when translated through the tag map associated with the tagged region, yields a unique 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 in turn is used to deternine 1 5 the location of the pen relative to a user interface element in the page description associated with the region.

Not only is the user interface element itself identified, but a location relative to the user interface element is identified. Location-indicating tags therefore trivially support the capture of an absolute pen path in the zone of a particular user interface element.

An object-indicating (or function-indicating) tag contains a tag ID which directly identifies a user interface element in the page description associated with the region (or equivalently, a function). All the tags in the zone of the user interface element identify the user interface 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. As an alternative, the netpage pen 10 1 can contain a pair or motion-sensing accelerometers, as described in our earlier application PCT/AUOO/00565.

With either tagging scheme, the tags function in cooperation with associated visual elements on the netpage as user interactive elements in that a user can interact with the printed page using an appropriate sensing device in order for tag data to be read by the sensing device and for an appropriate response to be generated in the netpage system.

Each application user interface flow is illustrated as a collection of documents linked by command arrows. A command arrow indicates that the target document is printed as a result of the user pressing the corresponding command button on the source page. Some command arrows are labelled with multiple conmnands separated by slashes indicating that any one of the specified commands causes the target document to be printed. Although multiple commands may label the same command arrow, they typically have different side-effects.

NPAI120AU In application terms, it is important to distinguish between netpage documents and netpage forms.

Documents contain printed information, as well as command buttons which can be pressed by the user to request further information or some other action. Forms, in addition to behaving like normal documents, also contain input fields which can be filled in by the user. They provide the system with a data input mechanism. It is also useful to distinguish between documents which contain generic information and documents which contain information specific to a particular interaction between the user and an application. Generic documents may be pre-printed publications such as magazines sold at news stands or advertising posters encountered in public places. Forms may also be pre-printed, including, for example, subscription forms encountered in preprinted publications. They may, of course, also be generated on-the-fly by a netpage printer in response to user requests. User-specific documents and forms are normally generated on the fly by a netpage printer in response to user requests. Figure 6 shows a generic document 990, a generic form 991, a user-specific document 992, and a user-specific form 993.

Netpages which participate in a user interface flow are further described by abstract page layouts.

A page layout may contain various kinds of elements, each of which has a unique style to differentiate it from the others. As shown in Figure 7, these include fixed information 994, variable information 995, input fields 996, command buttons 997, draggable commands 998, and text hyperlinks or hypertext links 999.

When a user interface flow is broken up into multiple diagrams, any document which is duplicated is shown with dashed outlines in all but the main diagram which defines it.

REMOTE CONFERENCING USING THE NETPAGE SYSTEM The netpage system, then, provides the facility for enabling remote conferencing, allowing geographically distributed participants to communicate graphical ideas via a shared whiteboard while engaged in a telephone conference or similar. Every time a participant adds a modification or a new piece of graphical information to the whiteboard the other participants are provided with an updated copy of the page. Each netpage or netpage document used during a conference session, such as a Conference Session Control Page (see below) or a version of a whiteboard which a participant is marking up, is a physical representation of what is referred to herein as a "conferencing form", containing the interactive objects (hyperlinks and form fields).

New whiteboard pages can be started at any time, but older pages or older versions of pages can still be marked up and re-distributed. Each participant ends up with a full history of the interaction.

APPLICATION DRAWING NOTATION Each application user interface flow is illustrated as a collection of documents linked by command arrows. A command arrow indicates that the target document is printed as a result of the user pressing the corresponding command button on the source page. Some command arrows are labelled with multiple commands separated by slashes indicating that any one of the specified commands causes the target document to be printed. 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.

NPA120AU Documents contain printed information, as well as command buttons which can be pressed by the user to request further information or some other action. Forms, in addition to behaving like normal documents, also contain input fields which can be filled in by the user. They provide the system with a data input mechanism. It is also useful to distinguish between documents which contain generic information and documents which contain information specific to a particular interaction between the user and an application. Generic documents may be pre-printed publications such as magazines sold at news stands or advertising posters encountered in public places. Forms may also be pre-printed, including, for example, subscription forms encountered in preprinted publications. They may, of course, also be generated on-the-fly by a netpage printer in response to user requests. User-specific documents and forms are normally generated on the fly by a netpage printer in response to user requests. Figure 44 shows a generic document 990, a generic form 991, a user-specific document 992, and a user-specific form 993.

Netpages which participate in a user interface flow are further described by abstract page layouts.

A page layout may contain various kinds of elements, each of which has a unique style to differentiate it from the others. As shown in Figure 45, these include fixed information 994, variable information 995, input fields 996, command buttons 997, draggable commands 998, and text hyperlinks or hypertext links 999.

When a user interface flow is broken up into multiple diagrams, any document which is duplicated is shown with dashed outlines in all but the main diagram which defines it.

CONFERENCING OBJECT MODEL The conferencing object model revolves around a conference session, a set of versioned whiteboard pages, and session participants. The conferencing class diagram is shown in Figure 8.

Each conference participant 502 is a netpage user 800, and has an access type 505 for a session, controlling the functions to which they have access. The access type specifies, for example, whether a participant is merely an observer, or whether he/she is permitted to make page markups, send messages, etc.

The possible access types are chairperson 509, organizer 510, author 511, markup allowed 512 and observer 513. The Access Type class dia-gram is shown in Figure 9.

Each conference session 500 has a unique session identifier 507, a session description, a planned start and end time, an actual start and end time, comments, and a status (indicating if the session is booked, in progress, finished or cancelled).

Associated with a conference session is a conference whiteboard made up of whiteboard pages 503, each of which may have a number of versions 504 associated with it. A version 504 is uniquely identified by a version number 508. Each version has a line style 506.

Before a session begins the whiteboard is empty. As the session progresses participants create new whiteboard pages, or make markups to existing whiteboard pages. Each time a markup is made and submitted by a participant, a new version of that whiteboard page is created. Each version records the date and time the version was created, the user who made the markups, and the markup content. In addition, each page version is also linked to the version of the page that was marked up to create this version. In this way a "tree" of versions NPA120AU 16is created for each white-board page, recording all the markups made during the session.

The first whiteboard page version is version 0 515. If this version is modified, version 1 516 is created. If version 1 is modified, version 2 is created, and so on. This is called the 'main branch' of the tree. If, however, at some stage during the session a user modifies an older version of the page, then the version numbering system branches. If a user later modifies version 1 then the tree branches and a new version 1.1 517 is created. An example of this version numbering system is shown in Figure 10. In this way, the evolution of each page (and thereby the information exchange process of the conference) can by clearly reviewed at any stage of the session.

CONFERENCING USER INTERFACE A user may obtain the Conference Session Menu 518 (not shown) from a variety of links including, for example: S a personalized bookmark kept by or available to the netpage user S the help menu 46 of the user's netpage printer The Conference Session Menu user interface flow is shown in Figure 11.

Optionally, security can be added to the conference session by adding signature verification at key points. A signature can be required, for example, on the session main page before a participant is allowed to send any markups.

Book a Conference Session A user may book a new conference session by clicking <Book New Session> on the Conference Session Menu 518. The Book A Conference Session page 519 is printed, shown in Figure 16. The user who creates a new conference session is referred to as the 'organizer'. The Book Conference Session user interface flow is shown in Figure 13.

To create a session the user specifies a short session description, the planned start date and time, and the planned end time for the session.

The user also specifies the participants to be invited to the session. One participant on the list may be flagged as the chairperson for the conference. If none is specified then, by default, the organizer is the chairperson. Participants may also be flagged as observers, observers having access types such that they may receive the whiteboard pages and all markups, but are not able to submit markups. The user may click the <Add Invitees> button 533 to obtain their contact list 523 (not shown) and select the participants.

Finally, for information purposes, the user may also include some comments relating to the session and its purpose.

When the details are complete the user clicks the <Send Invitation> button 534 to send the session invitation 524 to the participants via a netpage e-mail.

8.3.2 Conference Session List The user can print a list of their conference sessions by selecting the <List Sessions> button from NPA120AU -17the Conference Session Menu 518. The Conference Session List 520 (not shown) shows all sessions in which the user is a participant. For each session the list shows the session description, the user's access type for that session, the start date and time for the session, and the session's status.

The Conference Session List user interface flow is shown in Figure 12. From the Conference Session List 520 the user can cancel a session by clicking the <Cancel> button, or click <Details> to see the full details of the session. If the user cancels a session a Session Cancelled Notice 521 (not shown) is sent to particpants. If the session has not yet started, selecting <Details> prints a Conference Session Control Page 522 (see below). The session action buttons <Start Session> and <End Session> are only printed if the user is the meeting chairperson.

Conference Session Control A user may start a conference session by selecting <Details> for the session from the Session List.

If the session has not yet started then the Conference Session Control Page 522 is printed, shown in Figure 17.

If the user is the session chairperson, all the session action buttons are printed.

The chairperson clicks <Start Session> 535 to begin the conference session, and a Session Main Page 526 is printed on the netpage printer of each participant (Figure 18). The conference session then proceeds.

The chairperson clicks <End Session> 536 to end the current conference session. After this no more page markups can be submitted by the participants, and a Conference Session End Notice 532 is sent to all participants, shown in Figure At any time during or after a conference session, the chairperson may view the history 525 of the whiteboard markups by clicking <View History> 537. The tree view of page versions is printed, with each version being shown as a thumbnail image together with its version number and the name of the user who created it. The chairperson can then print a full size copy of the page version by clicking on it.

At any time during or after a markup session, a user may list messages sent during the session. The message list 528 only shows messages which were addressed to the user.

A Conference Session The user interface flow for a conference session is shown in Figure As explained above, when the session is started by the chairperson a Session Main Page 526 is printed on the netpage printer of each participant. The Session Main Page, shown in Figure 18, gives the session details, the participants' names and access types.

If the user clicks the <New Page> 539 button on the Session Main Page, a blank whiteboard page (Figure 19) is printed.

If the user clicks the <Print Palette> button on the Session Main Page, a palette 529 (not shown) of available line styles and colors is printed. The user can select the line style and color to use when writing on the whiteboard page. The palette choice can be changed at any time during the session. The current line style NPA120AU

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-18and color becomes a property of any captured digital ink.

During a session a participant can send a message 531 to the other participants, the message 531 printing directly onto the netpage printer of the addressees. The messages are recorded against the conference session, and may be printed at any time during or after the session, but messages can of course only be viewed by the message addressees. To send a message the user clicks the <Send Message> button and the Compose Message page 530 is printed, as shown in Figure 21.

The whiteboard page 527 is shown in Figure 19. The top of the whiteboard page shows the session description, whiteboard page number, version number, the current date and time, and the name of the participant who made the latest markups.

The page version may be reprinted, discarding any markups made on the page by the user, by clicking the <Reprint> button.

The user can select content on another netpage using an available netpage selection mechanism by 'lassoing' and selecting the desired content from another netpage with the netpage pen). The user can then paste the selected content to the whiteboard page by drawing a line from the <Paste> icon to the desired paste point on the page.

If at any stage the user clicks the <Update> button then their marked-up whiteboard page is stored as a new version and is sent to all session participants.

If the user clicks the <New Page> button a blank whiteboard page is printed on their printer, as shown in Figure 19.

The user interface flow for a whiteboard page is shown in Figure 14, whilst the user interface flow for a conference session is shown in Figure The tree view of page versions is printed on the back of each whiteboard page. If the entire tree does not fit on one page then as much as possible of the current branch is shown. Each version is shown as a thumbnail image, and beside the image is the version number and the update user name. The user can then print a full size copy of the page version by clicking on it.

As explained above, once the chairperson has ended a current conference session, no more page markups can be submitted by the participants, and a Conference Session End Notice 532 (Figure 20) is sent to all participants.

WHITEBOARD SESSIONS USING THE NETPAGE SYSTEM Additionally, then, the netpage system can be employed in the provision of a whiteboard facility for users in an educational or meeting environment who are not geographically remote from one another.

NETPAGE WHITEBOARD PAD APPLICATION An easel holding a pad of large-format Al or AO) pre-printed netpage paper acts as the whiteboard. Participants in a meeting can collaboratively mark up the physical pages, and at the end of the NPA120AU

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-19meeting can print out a reduced-size version of the whiteboard pages, such as an A4 version, conveniently bound and timestamped. Multiple colored netpage pens can be used during a session, and since each pen can inform the system of its color and style, the reduced pages can faithfully reproduce the colors used.

The whiteboard pad application records each page of a pre-printed whiteboard pad as belonging to a particular pad, as shown in the Whiteboard Pad and Session class diagram in Figure 22. When a user starts a new session 541, the application records the pad page 542 through which the user starts the session 541 as being the first page of the session. Any other pages belonging to the same pad 540 which are marked by a user using a netpage pen while the session is active are also recorded as belonging to the session.

Each pad page 543 contains pre-printed buttons for starting, ending and printing a session, as shown in Figure 24. As shown in the user interface flow in Figure 23, when a user presses the <start session> button 547, the application prints a session start page 544 which gives the start time of the session. When a session is active in relation to a particular pad, any attempt to start a new session elicits an error report.

Alternatively or additionally, the application may be configured such that, if the user marks a pad page when no session is active, a new session is automatically started.

When the user presses the <end session> button 548, the application prints a session end page 545 which gives the start and end times of the session. When no session is active in relation to a particular pad, any attempt to end a session elicits an error report.

Each pad page 543, as well as the session start page 544 and the session end page 545, provides a <print session> button 549 which can be used at any time to print the pages of the corresponding session. Each session page 546 is printed with the session start and end dates and times, as well as a page number within the session, as shown in Figure As an alternative to the above, the whiteboard pad comprises essentially blank pages, preprinted with coded data for detection by the netpage pen, and the pad is provided on a cardboard or other backing sheet. The backing sheet extends beyond the periphery of the pages, for example below the bottom of the pages, to provide a projecting margin which includes a single set of session control buttons. These can be used to control any number of sessions held using the pad, although only one session at a time, of course. Because the whiteboard pad application knows which pad the control buttons belong to, it knows which pad, and therefore which session, the control buttons operate on.

CONCLUSION

The present invention has been described with reference to a preferred embodiment and number of specific alternative embodiments. However, it will be appreciated by those skilled in the relevant fields that a number of other embodiments, differing from those specifically described, will also fall within the spirit and scope of the present invention. Accordingly, it will be understood that the invention is not intended to be limited to the specific embodiments described in the present specification, including documents incorporated by cross-reference as appropriate. The scope of the invention is only limited by the attached claims.

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Claims (24)

1. A method of capturing, in a computer system, data relating to a note-taking session, the session consisting of handwritten annotations made by a user by way of a writing implement on a plurality of pages, said pages including coded data indicative of at least one reference point of the page and the method including the steps of: receiving, in the computer system and via the writing implement, an indication of the start of the note-taking session; receiving, in the computer system and via the writing implement, data indicative of said handwritten annotations made by said user on said plurality of pages; receiving, in the computer system and via the writing implement, an indication of the end of the note-taking session; and retaining a retrievable record of the received data for the note-taking session, wherein the writing implement comprises: an image sensor adapted to capture images of at least some of the coded data when the writing implement is placed in an operative position relative to the page; and a processor adapted to: identify at least some of the coded data from one or more of the captured images; (ii) determine an orientation, within the captured images, of at least some of the coded data; (iii) decode at least some of the coded data; (iv) generate the data regarding said indication of at least one of the start and the end of the note-taking session using at least some of the decoded coded data; and generate the data indicative of said handwritten annotations using at least some of the decoded coded data.

2. The method of claim 1, wherein the processor is housed within the writing implement.

3. The method of claim 1, wherein the image sensor is housed within the writing implement.

4. The method of claim 1, wherein the coded data comprises non-barcode coded data. NPA120AU The method according to claim 1, wherein each of the pages includes coded data indicative of an identity of the page, and said writing implement is adapted to detect at least some of said coded data indicative of the identity of the page.

6. The method according to claim 1, wherein said indication of the start of the note-taking session is provided by the computer system receiving data indicative of said handwritten annotations made by said user on said plurality of pages.

7. The method according to claim 1, wherein said plurality of pages is associated with a control portion comprising at least one control zone, the computer system receiving an indication via said writing implement that said user has designated one or more control zones using the writing implement.

8. The method according to claim 7, wherein one or more of said pages includes said control portion.

9. The method according to claim 7, wherein said plurality of pages are provided in the form of a notepad, the notepad includes said control portion on a part of the notepad other than on one of said pages. The method according to claim 7, wherein said at least one control zone includes a zone associated with the start of the note-taking session, and said indication of the start of the note-taking session is provided by the computer system receiving an indication that said user has designated said zone by way of said writing implement.

11. The method according to claim 7, wherein said at least one control zone includes a zone associated with the end of the note-taking session, and said indication of the end of the note-taking session is provided by the computer system receiving an indication that said user has designated said zone by way of said writing implement.

12. The method according to claim 1, wherein said writing implement includes a writing nib, and said writing nib is associated with a sensor able to detect nib contact with one of said plurality of pages.

13. The method according to claim 1 including the step of using said retrievable record to selectively print the data indicative of said handwritten annotations. NPA120AU -22

14. The method according to claim 13, wherein said plurality of pages is associated with a control portion including a zone associated with the printing of the note-taking session, the computer system receiving an indication via said writing implement that said user has designated said zone using the writing implement. The method according to claim 13, the data being printable on a plurality of pages corresponding to the plurality of pages annotated in the note-taking session.

16. A system for capturing data relating to a note-taking session, the session consisting of handwritten annotations made by a user by way of a writing implement on a plurality of pages, said pages including coded data indicative of at least one reference point of the page and the system including: a computer system for receiving indicating data via the writing implement operated by the user, said indicating data regarding at least one of a position and a movement of the writing implement relative to a page, the computer system including: a start/end-identifier for identifying, from the indicating data, an indication of the start of the note-taking session and an indication of the end of the note-taking session; and a memory for retaining a retrievable record of the received data for the note-taking session, said retrievable record being indicative of said handwritten annotations made by said user on said plurality of pages between the start and end of the note-taking session, wherein the writing implement comprises: an image sensor adapted to capture images of at least some of the coded data when the writing implement is placed in an operative position relative to the page; and a processor adapted to: identify at least some of the coded data from one or more of the captured images; (ii) determine an orientation, within the captured images, of at least some of the coded data; (iii) decode at least some of the coded data; and (iv) generate the indicating data using at least some of the decoded coded data.

17. The system according to claim 16, including the plurality of pages. NPA120AU 23

18. The system according to claim 17, wherein each page includes coded data indicative of an identity of the page, said indicating data being indicative of the identity of the page and at least one of the position and the movement of the writing implement relative to a page.

19. The system of claim 16, wherein the processor is housed within the writing implement.: The system of claim 16, wherein the image sensor is housed within the writing implement.

21. The system of claim 16, wherein the coded data comprises non-barcode coded data.

22. The system according to claim 16 including the writing implement.

23. The system according to claim 22, wherein said writing implement includes a writing nib, and said writing nib is associated with a sensor able to detect nib contact with one of said plurality of pages.

24. The system according to claim 16 including a plurality of pages, said plurality of pages being associated with a control portion comprising at least one control zone, the computer system receiving an indication via said writing implement that said user has designated one or more control zones using the writing implement. The system according to claim 24, wherein one or more of said pages includes said control portion.

26. The system according to claim 24 including at least one notepad incorporating said plurality of pages, the at least one notepad including said control portion on a part of the notepad other than on one of said pages.

27. The system according to claim 24, wherein said at least one control zone includes a session start zone, said means for identifying an indication of the start of the note-taking session comprises means for receiving an indication that said user has designated said zone by way of said writing implement. NPA120AU -24-

28. The system according to claim 24, wherein said at least one control zone includes a session end zone, said means for identifying an indication of the end of the note-taking session comprises means for receiving an indication that said user has designated said zone by way of said writing implement.

29. The system according to claim 24, wherein said at least one control zone includes a print zone, said system including means for receiving an indication that said user has designated said print zone by way of said writing implement and means, in response to said indication, to print from said retrievable record data indicative of said handwritten annotations. NPA120AU