A printer for receiving document data from a computer system and printing an interface onto a surface. The interface is based on the document data, which includes identity data indicative of at least one identity. The identity is, in turn, associated with a region of the interface. The interface also includes coded data. The printer includes a coded data generator configured to generate the coded data based at least partially on the identity data. A printing mechanism in the printer prints the interface onto the surface.
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/granted patents filed by the applicant or assignee of the present invention on 15 Sep. 2000:
| |
| | 6,679,420 | 09/669,599 | 09/663,701 |
| | 6,720,985 |
| |
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/granted patents filed by the applicant or assignee of the present invention on 30 Jun. 2000:
| |
| | 09/609,139 | 09/608,970 | 6,678,499 |
| | 09/607,852 | 09/607,656 | 6,766,942 |
| | 09/609,303 | 09/610,095 | 09/609,596 |
| | 09/607,843 | 09/607,605 | 09/608,178 |
| | 09/609,553 | 09/609,233 | 09/609,149 |
| | 09/608,022 | 09/608,920 | 09/607,844 |
| | 6,457,883 | 6,394,573 | 09/607,985 |
| | 6,398,332 | | 6,622,923 |
| |
Various methods, systems and apparatus relating to the present invention are disclosed in the following co-pending applications/granted patents filed by the applicant or assignee of the present invention on 23 May 2000:
| 09/575,197, | 09/575,195, | 09/575,159, | 09/575,132, |
| 09/575,123, | 6,825,945, | 09/575,130, | 09/575,165, |
| 6,813,039, | 09/575,116, | 09/575,118, | 09/575,131, |
| 6,816,274, | 09/575,139, | 09/575,186, | 6,681,045, |
| 6,728,000, | 09/575,145, | 09/575,192, | 09/757,181, |
| 09/575,193, | 09/575,183, | 6,789,194, | 09/575,150, |
| 6,789,191, | 6,622,999, | 6,644,642, | 6,502,614, |
| 6,669,385, | 6,549,935, | 09/575,187, | 6,272,996, |
| 6,591,884, | 6,439,706, | 6,760,119, | 09/575,198, |
| 6,290,349, | 6,428,155, | 6,785,016, | 6,870,966, |
| 6,822,639, | 09/575,129, | 6,737,591, | 09/575,154, |
| 6,830,196, | 09/575,162, | 6,832,717, | 09/575,189, |
| 09/575,172, | 09/575,170, | 09/575,171, | 09/575,161, |
| 6,28,133, | 6,526,658, | 6,315,699, | 6,338,548, |
| 6,540,319, | 6,328,431, | 6,328,425, | 09/575,127, |
| 6,383,833, | 6,464,332, | 6,390,591, | 09/575,152, |
| 6,328,417, | 6,409,323, | 6,281,912, | 6,604,810, |
| 6,318,920, | 6,488,422, | 6,795,215, | 09/575,109, |
| 6,859,289 |
The disclosures of these co-pending applications are incorporated herein by-cross-reference.
BACKGROUND
Presently, a user of a computer system typically interacts with the system using a monitor for displaying information and a keyboard and/or mouse for inputting information. Whilst such an interface is powerful, it is relatively bulky and non-portable. Information printed on paper can be easier to read and more portable than information displayed on a computer monitor. However, unlike a keyboard or mouse, a pen on paper generally lacks the ability to interact with computer software.
SUMMARY OF INVENTION
According to a first aspect of the invention, there is provided a printer for receiving document data from a computer system and printing an interface onto a surface, the interface being at least partially based on the document data, the document data including identity data indicative of at least one identity, the identity being associated with a region of the interface, the interface including coded data, the printer including:
a coded data generator configured to generate the coded data based at least partially on the identity data; and a printing mechanism for printing the interface onto the surface. The coded data is preferably substantially invisible to the average unaided human eye under daylight or ambient lighting conditions.
Preferably, the interface includes information in addition to the coded data, the information being based at least partially on the document data. Preferably this information is substantially visible to the average unaided human eye under daylight or ambient lighting conditions.
In a preferred embodiment, the coded data is also indicative of at least one reference point of the region. More preferably, the at least one reference point is determined on the basis of a coded data layout.
In one embodiment, the printer is configured to receive the coded data layout from the computer system. Alternatively, or in addition, the printer further includes storage means for storing a plurality of the coded data layouts, the printer being configured to:
receive, from the computer system, layout selection information indicative of one of the coded data layouts; and use the layout selection information to select one of the stored coded layouts for use in determining the at least one reference point. Preferably, the coded data is not substantially visible to an average unaided human eye under daylight or ambient lighting conditions.
In a preferred embodiment, the coded data includes at least one tag, each tag being indicative of the identity of the region.
According to a second aspect of the invention, there is provided an interface surface produced by a printer according to the first aspect.
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:
FIG. 1 is a schematic of a the relationship between a sample printed netpage and its online page description;
FIG. 2 is a schematic view of a interaction between a netpage pen, a netpage printer, a netpage page server, and a netpage application server;
FIG. 3 illustrates a collection of netpage servers and printers interconnected via a network;
FIG. 4 is a schematic view of a high-level structure of a printed netpage and its online page description;
FIG. 5
a is a plan view showing a structure of a netpage tag;
FIG. 5
b is a plan view showing a relationship between a set of the tags shown in FIG. 5
a and a field of view of a netpage sensing device in the form of a netpage pen;
FIG. 6
a is a plan view showing an alternative structure of a netpage tag;
FIG. 6
b is a plan view showing a relationship between a set of the tags shown in FIG. 6
a and a field of view of a netpage sensing device in the form of a netpage pen;
FIG. 6
c is a plan view showing an arrangement of nine of the tags shown in FIG. 6
a where targets are shared between adjacent tags;
FIG. 6
d is a plan view showing the interleaving and rotation of the symbols of the four codewords of the tag shown in FIG. 6
a; FIG. 7 is a flowchart of a tag image processing and decoding algorithm;
FIG. 8 is a perspective view of a netpage pen and its associated tag-sensing field-of-view cone;
FIG. 9 is a perspective exploded view of the netpage pen shown in FIG. 8;
FIG. 10 is a schematic block diagram of a pen controller for the netpage pen shown in FIGS. 8 and 9;
FIG. 11 is a perspective view of a wall-mounted netpage printer;
FIG. 12 is a section through the length of the netpage printer of FIG. 11;
FIG. 12
a is an enlarged portion of FIG. 12 showing a section of the duplexed print engines and glue wheel assembly;
FIG. 13 is a detailed view of the ink cartridge, ink, air and glue paths, and print engines of the netpage printer of FIGS. 11 and 12;
FIG. 14 is a schematic block diagram of a printer controller for the netpage printer shown in FIGS. 11 and 12;
FIG. 15 is a schematic block diagram of duplexed print engine controllers and Memjet™ printheads associated with the printer controller shown in FIG. 14;
FIG. 16 is a schematic block diagram of the print engine controller shown in FIGS. 14 and 15;
FIG. 17 is a perspective view of a single Memjet™ printing element, as used in, for example, the netpage printer of FIGS. 10 to 12;
FIG. 18 is a perspective view of a small part of an array of Memjet™ printing elements;
FIG. 19 is a series of perspective views illustrating the operating cycle of the Memjet™ printing element shown in FIG. 13;
FIG. 20 is a perspective view of a short segment of a pagewidth Memjet™ printhead;
FIG. 21 is a schematic view of a user class diagram;
FIG. 22 is a schematic view of a printer class diagram;
FIG. 23 is a schematic view of a pen class diagram;
FIG. 24 is a schematic view of an application class diagram;
FIG. 25 is a schematic view of a document and page description class diagram;
FIG. 26 is a schematic view of a document and page ownership class diagram;
FIG. 27 is a schematic view of a terminal element specialization class diagram;
FIG. 28 is a schematic view of a static element specialization class diagram;
FIG. 29 is a schematic view of a hyperlink element class diagram;
FIG. 30 is a schematic view of a hyperlink element specialization class diagram;
FIG. 31 is a schematic view of a hyperlinked group class diagram;
FIG. 32 is a schematic view of a form class diagram;
FIG. 33 is a schematic view of a digital ink class diagram;
FIG. 34 is a schematic view of a field element specialization class diagram;
FIG. 35 is a schematic view of a checkbox field class diagram;
FIG. 36 is a schematic view of a text field class diagram;
FIG. 37 is a schematic view of a signature field class diagram;
FIG. 38 is a flowchart of an input processing algorithm;
FIG. 38
a is a detailed flowchart of one step of the flowchart of FIG. 38;
FIG. 39 is a schematic view of a page server command element class diagram;
FIG. 40 is a schematic view of a resource description class diagram;
FIG. 41 is a schematic view of a favorites list class diagram;
FIG. 42 is a schematic view of a history list class diagram;
FIG. 43 is a schematic view of a subscription delivery protocol;
FIG. 44 is a schematic view of a hyperlink request class diagram;
FIG. 45 is a schematic view of a hyperlink activation protocol;
FIG. 46 is a schematic view of a form submission protocol;
FIG. 47 is a schematic view of a commission payment protocol;
FIG. 48 is a flowchart of document processing in a netpage printer;
FIG. 49 is a schematic view of a set of radial wedges making up a symbol;
FIG. 50 is a schematic view of a ring A and B symbol allocation scheme;
FIG. 51 is a schematic view of a first ring C and D symbol allocation scheme;
FIG. 52 is a schematic view of a second ring C and D symbol allocation scheme;
FIG. 53 is a simple exploded view of the wallprinter;
FIG. 54 is an exploded view of the ink cartridge;
FIG. 55 is a pair of three-quarter views of the ink cartridge;
FIG. 56 is a three-quarter view of a single ink bladder;
FIGS. 57
a and 57
b are lateral and longitudinal sections through the ink cartridge;
FIG. 58 is a front three-quarter view of the open media tray;
FIG. 59 is a front three-quarter view of the electrical system of the printer;
FIG. 60 is a rear three-quarter view of the electrical system;
FIG. 61 is a front three-quarter view of the wallprinter with the lower front cover removed;
FIG. 62 is a section through the binder assembly;
FIG. 63 is a rear three-quarter view of the open glue wheel assembly;
FIG. 64 is a section through the binding assembly and the exit hatch;
FIG. 65 is a three-dimensional view of an interface module;
FIG. 66 is an exploded view of an interface module;
FIG. 67 is a top three-quarter view of the media tray; and
FIG. 68 is a section through the top part of the printer.
DETAILED DESCRIPTION OF PREFERRED AND OTHER EMBODIMENTS
Note: Memjet™ is a trade mark of Silverbrook Research Pty Ltd, Australia.
In the preferred embodiment, the invention is configured to work with the netpage networked computer system, a detailed overview of which follows. It will be appreciated that not every implementation will necessarily embody all or even most of the specific details and extensions discussed below in relation to the basic system. However, the system is described in its most complete form to reduce the need for external reference when attempting to understand 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 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, 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. Substrates other than paper may be used. The encoded information in the preferred embodiment is an infrared absorptive ink and so an infrared sensitive optical sensor may be used. If desired other wavelengths may be used or sensing techniques other than optical sensing; one alternative is to use magnetic inks and sensors.
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 FIG. 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 (i.e. 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 FIG. 2, the netpage pen
101, a preferred form of which is shown in FIGS. 8 and 9 and described in more detail below, works in conjunction with a netpage printer
601, an Internet-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. If desired the pen may be connected to the system utilizing wires or an infrared transmitter, although both alternatives limit usability.
The netpage printer
601, a preferred form of which is shown in FIGS. 11 to 13 and described in more detail below, 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 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 FIG. 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™) printers. 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. Cable service is available to 95% of households in the United States, and cable modem service offering broadband Internet access is already available to 20% of these. The netpage printer can also operate with slower connections, but either with longer delivery times or lower image quality or both. Indeed, the netpage system can 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, assuming that the assigned pen is only used by the respective family member. However, as explained below, other means may be used to identify a user.
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.
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 email address. Alternatively the entire system may be made visible to outside users or each user may be provided with the ability to expose their printer(s) to outside users. This may be by way of selecting outside users allowed too send junk mail.
1 Netpage System Architecture
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 labeled 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 modeled.
An association is drawn as a line joining two classes, optionally labeled 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 labeled with its name, and is also optionally labeled 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-a") 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.
1.1 Netpages
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 tags may be printed on or into the surface of the page, may be in or on a sub-layer of the page or may be otherwise incorporated into 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. The page descriptions of different netpages may share components, such as an image, although the netpages (and the associated page descriptions) are visibly different. The page description for each netpage may include references to these common components. 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 all netpages envisaged to be used in the environment of use. If the environment is small then the precision need not be as great as where the environment is large.
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. In the preferred embodiments 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 image sensor with an appropriate filter. A sensor sensitive to the relative wavelength or wavelengths may be used, in which case no filters are required. Other wavelengths may be used, with appropriate substrates and sensors.
A tag is sensed by an area image sensor in the netpage pen, decoded and the data encoded by the tag is transmitted to the netpage system, preferably 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 tag and extract 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 FIG. 4. In the preferred embodiment the page instance is associated with both the netpage printer which printed it and, if known, the netpage user who requested it. It is not essential to the working of the invention in its basic form that the page instance be associated with either the netpage printer which printed the corresponding physical page or the netpage user who requested it or for whom the page was printed.
1.2 Netpage Tags
1.2.1 Tag Data Content
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 of a hyperlink.
As will be more clearly explained below, 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 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 (˜10
27 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, interleaved with the first, encoding y coordinates. It will be appreciated the region ID and tag ID precision may be more or less than just described depending on the environment in which the system will be used.
1.2.2 Tag Data Encoding
In one embodiment each tag contains 120 bits of information. The 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 maximizing 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).
1.2.3 Physical Tag Structure
The physical representation of the tag, shown in FIG. 5, 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 three-dimensional orientation relative to the sensor. The data areas contain representations of the individual bits of the encoded tag data.
To achieve proper tag reproduction, the tag is rendered at a resolution of 256×256 dots. When printed at 1600 dots per inch this yields a tag with a diameter of about 4 mm. At this resolution the tag is designed to be surrounded by a "quiet area" of radius 16 dots. Since the quiet area is also contributed by adjacent tags, it only adds 16 dots to the effective diameter of the tag.
The tag includes six target structures. A detection ring
15 allows the sensing device to initially detect the tag. The ring is easy to detect because it is rotationally invariant and because a simple correction of its aspect ratio removes most of the effects of perspective distortion. An orientation axis
16 allows the sensing device to determine the approximate planar orientation of the tag due to the yaw of the sensor. The orientation axis is skewed to yield a unique orientation. Four perspective targets
17 allow the sensing device to infer an accurate two-dimensional perspective transform of the tag and hence an accurate three-dimensional position and orientation of the tag relative to the sensor.
All target structures are redundantly large to improve their immunity to noise.
The overall tag shape is circular. This supports, amongst other things, optimal tag packing on an irregular triangular grid, such as is required to tile an arbitrary non-planar surface. The tags may, however, be arranged at the apexes of any polygon having n apexes, where n ranges from 3 to infinity, as desired. In combination with the circular detection ring
15, this makes a circular arrangement of data bits within the tag optimal. As shown in FIG. 48, to maximize its size, each data bit is represented by a radial wedge
510 in the form of an area bounded by two radial lines
512, a radially inner arc
514 and a radially outer arc
516. Each wedge
510 has a minimum dimension of 8 dots at 1600 dpi and is designed so that its base (i.e. its inner arc
514), is at least equal to this minimum dimension. The radial height of the wedge
510 is always equal to the minimum dimension. Each 4-bit data symbol is represented by an array
518 of 2×2 wedges
510, as best shown in FIG. 48.
The 15 4-bit data symbols of each of the six codewords are allocated to the four concentric symbol rings
18a to
18d, shown in FIG. 5, in interleaved fashion as shown in FIGS. 49 to 51. Symbols of first to sixth codewords
520-
525 are allocated alternately in circular progression around the tag.
The interleaving is designed to maximize the average spatial distance between any two symbols of the same codeword. Other arrangements of the codewords or their data symbols may be utilized.
The physical layout of the tags or the shape and/or arrangement of data symbols within each tag are nor essential to the working of the invention. It is merely necessary that each tag encode sufficient information for the intended use. The use of redundancy in the tag is preferred but, at its basic level, not truly essential to the working of the invention. As such other tag arrangements may be utilized. Examples of other tag structures are described in U.S. Pat. Nos. 5,625,412, 5,661,506, 5,477,012 and 5,852,434, and PCT application PCT/US98/20597, the contents of each of which are incorporated herein by reference.
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 the sensing device 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 is obtained when the tags are tiled on a equilateral triangular grid, as shown in FIG. 6.
1.2.4 Tag Image Processing and Decoding
The tag image processing and decoding of a tag of FIG. 5 performed by a sensing device such as the netpage pen is shown in FIG. 7. While a captured image is being acquired from the image sensor, the dynamic range of the image is determined (at
20). The center of the range is then chosen as the binary threshold for the image
21. The image is then thresholded and segmented into connected pixel regions (i.e. shapes
23) (at
22). Shapes which are too small to represent tag target structures are discarded. The size and centroid of each shape is also computed.
Binary shape moments
25 are then computed (at
24) for each shape, and these provide the basis for subsequently locating target structures. Central shape moments are by their nature invariant of position, and can be easily made invariant of scale, aspect ratio and rotation.
The ring target structure
15 is the first to be located (at
26). A ring has the advantage of being very well behaved when perspective-distorted. Matching proceeds by aspect-normalizing and rotation-normalizing each shape's moments. Once its second-order moments are normalized the ring is easy to recognize even if the perspective distortion was significant. The ring's original aspect and rotation
27 together provide a useful approximation of the perspective transform.
The axis target structure
16 is the next to be located (at
28). Matching proceeds by applying the ring's normalizations to each shape's moments, and rotation-normalizing the resulting moments. Once its second-order moments are normalized the axis target is easily recognized. Note that one third order moment is required to disambiguate the two possible orientations of the axis. The shape is deliberately skewed to one side to make this possible. Note also that it is only possible to rotation-normalize the axis target after it has had the ring's normalizations applied, since the perspective distortion can hide the axis target's axis. The axis target's original rotation provides a useful approximation of the tag's rotation due to pen yaw
29.
The four perspective target structures
17 are the last to be located (at
30). Good estimates of their positions are computed based on their known spatial relationships to the ring and axis targets, the aspect and rotation of the ring, and the rotation of the axis. Matching proceeds by applying the ring's normalizations to each shape's moments. Once their second-order moments are normalized the circular perspective targets are easy to recognize, and the target closest to each estimated position is taken as a match. The original centroids of the four perspective targets are then taken to be the perspective-distorted corners
31 of a square of known size in tag space, and an eight-degree-of-freedom perspective transform
33 is inferred (at
32) based on solving the well-understood equations relating the four tag-space and image-space point pairs (see Heckbert, P., Fundamentals of Texture Mapping and Image Warping, Masters Thesis, Dept. of EECS, U. of California at Berkeley, Technical Report No. UCB/CSD 89/516, June 1989, the contents of which are herein incorporated by cross-reference).
The inferred tag-space to image-space perspective transform is used to project (at
36) each known data bit position in tag space into image space where the real-valued position is used to bilinearly interpolate (at
36) the four relevant adjacent pixels in the input image. The previously computed image threshold
21 is used to threshold the result to produce the final bit value
37.
Once all 360 data bits
37 have been obtained in this way, each of the six 60-bit Reed-Solomon codewords is decoded (at
38) to yield 20 decoded bits
39, or 120 decoded bits in total. Note that the codeword symbols are sampled in codeword order, so that codewords are implicitly de-interleaved during the sampling process.
As mentioned above, the physical tag structure or encoding system is not essential to the invention and other physical arrangements of each tag may be used. It will be understood that the process for recognizing and decoding the tag image to retrieve the data encoded depends on the physical structure of the tag and the system used for redundantly encoding the data.
The ring target
15 is only sought in a subarea of the image whose relationship to the image guarantees that the ring, if found, is part of a complete tag. If a complete tag is not found and successfully decoded, then no pen position is recorded for the current frame. Given adequate processing power and ideally a non-minimal field of view
193, an alternative strategy involves seeking another tag in the current image.
The obtained tag data indicates the identity of the region containing the tag and the position of the tag within the region. An accurate position
35 of the pen nib in the region, as well as the overall orientation
35 of the pen, is then inferred (at
34) from the perspective transform
33 observed on the tag and the known spatial relationship between the pen's physical axis and the pen's optical axis.
1.2.5 Alternative Tag Structures
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 FIG. 6
a. The alternative tag
4 is square and has four perspective targets
17. It is similar in structure to tags described by Bennett et al. in U.S. Pat. No. 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 FIGS. 6
b and
6c. FIG. 6
b shows a square tiling of 16 tags and the corresponding minimum field of view
193, which must span the diagonals of two tags. FIG. 6
c 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. Tag image processing proceeds as described in section 1.2.4 above, with the exception that steps
26 and
28 are omitted.
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 FIG. 6
d, where each symbol is labelled with the number of its codeword (1-4) and the position of the symbol within the codeword (A-O). 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).
1.2.6 Tag Map
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. The tag map class diagram is shown in FIG. 22, as part of the netpage printer class diagram.
A tag map reflects the scheme used to tile the surface region with tags, and this can vary according to surface type. When multiple tagged regions share the same tiling scheme and the same tag numbering scheme, they can also share the same tag map.
The tag map for a region must be 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 tag-relative pen location can be added to the tag location to yield an absolute pen location within the region.
1.2.7 Tagging Schemes
Two distinct surface coding schemes are of interest, both of which use the tag structure described earlier in this section. The preferred coding scheme uses "location-indicating" tags as already discussed. An alternative coding scheme uses "object-indicating" tags.
A location-indicating tag 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 determine 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 tag contains a tag ID which directly identifies a user interface element in the page description associated with the region. 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.
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.
1.3 Document and Page Descriptions
A preferred embodiment of a document and page description class diagram is shown in FIGS. 25 and 26.
In the netpage system a document is described at three levels. At the most abstract level the document
836 has a hierarchical structure whose terminal elements
839 are associated with content objects
840 such as text objects, text style objects, image objects, etc. Once the document is printed on a printer with a particular page size and according to a particular user's scale factor preference, the document is paginated and otherwise formatted. Formatted terminal elements
835 will in some cases be associated with content objects which are different from those associated with their corresponding terminal elements, particularly where the content objects are style-related. Each printed instance of a document and page is also described separately, to allow input captured through a particular page instance
830 to be recorded separately from input captured through other instances of the same page description.
The presence of the most abstract document description on the page server allows a user to request a copy of a document without being forced to accept the source document's specific format. The user may be requesting a copy through a printer with a different page size, for example. Conversely, the presence of the formatted document description on the page server allows the page server to efficiently interpret user actions on a particular printed page.
A formatted document
834 consists of a set of formatted page descriptions
5, each of which consists of a set of formatted terminal elements
835. Each formatted element has a spatial extent or zone
58 on the page. This defines the active area of input elements such as hyperlinks and input fields.
A document instance
831 corresponds to a formatted document
834. It consists of a set of page instances
830, each of which corresponds to a page description
5 of the formatted document. Each page instance
830 describes a single unique printed netpage
1, and records the page ID
50 of the netpage. A page instance is not part of a document instance if it represents a copy of a page requested in isolation.
A page instance consists of a set of terminal element instances
832. An element instance only exists if it records instance-specific information. Thus, a hyperlink instance exists for a hyperlink element because it records a transaction ID
55 which is specific to the page instance, and a field instance exists for a field element because it records input specific to the page instance. An element instance does not exist, however, for static elements such as textflows.
A terminal element can be a static element
843, a hyperlink element
844, a field element
845 or a page server command element
846, as shown in FIG. 27. A static element
843 can be a style element
847 with an associated style object
854, a textflow element
848 with an associated styled text object
855, an image element
849 with an associated image element
856, a graphic element
850 with an associated graphic object
857, a video clip element
851 with an associated video clip object
858, an audio clip element
852 with an associated audio clip object
859, or a script element
853 with an associated script object
860, as shown in FIG. 28.
A page instance may have a background field
833 which is used to record any digital ink captured on the page which does not apply to a specific input element.
In the preferred form of the invention, a tag map
811 is associated with each page instance to allow tags on the page to be translated into locations on the page.
1.4 The Netpage Network
In a preferred embodiment, a netpage network consists of a distributed set of netpage page servers
10, netpage registration servers
11, netpage ID servers
12, netpage application servers
13, netpage publication servers
14, and netpage printers
601 connected via a network
19 such as the Internet, as shown in FIG. 3.
The netpage registration server
11 is a server which records relationships between users, pens, printers, applications and publications, and thereby authorizes various network activities. It authenticates users and acts as a signing proxy on behalf of authenticated users in application transactions. It also provides handwriting recognition services if desired. As described above, a netpage page server
10 maintains persistent information about page descriptions and page instances. The netpage network includes any number of page servers, each handling a subset of page instances. Since a page server also maintains user input values for each page instance, clients such as netpage printers send netpage input directly to the appropriate page server. The page server interprets any such input relative to the description of the corresponding page.
A netpage ID server
12 allocates document IDs
51 on demand, and provides load-balancing of page servers via its ID allocation scheme.
A netpage printer uses the Internet Distributed Name System (DNS), or similar, to resolve a netpage page ID
50 into the network address of the netpage page server handling the corresponding page instance.
A netpage application server
13 is a server which hosts interactive netpage applications. A netpage publication server
14 is an application server which publishes netpage documents to netpage printers. They are described in detail in Section 2.
Netpage servers can be hosted on a variety of network server platforms from manufacturers such as IBM, Hewlett-Packard, and Sun. Multiple netpage servers can run concurrently on a single host, and a single server can be distributed over a number of hosts. Some or all of the functionality provided by netpage servers, and in particular the functionality provided by the ID server and the page server, can also be provided directly in a netpage appliance such as a netpage printer, in a computer workstation, or on a local network.
1.5 The Netpage Printer
The netpage printer
601 is an appliance which is registered with the netpage system and prints netpage documents on demand and via subscription. Each printer has a unique printer ID
62, and is connected to the netpage network via a network such as the Internet, ideally via a broadband connection.
Apart from identity and security settings in non-volatile memory, the netpage printer need not contain any persistent storage. As far as a user is concerned, "the network is the computer". Netpages function interactively across space and time with the help of the distributed netpage page servers
10, independently of particular netpage printers.
The netpage printer receives subscribed netpage documents from netpage publication servers
14. Each document is distributed in two parts: the page layouts, and the actual text and image objects which populate the pages. Because of personalization, page layouts are typically specific to a particular subscriber and so are pointcast to the subscriber's printer via the appropriate page server. Text and image objects, on the other hand, are typically shared with other subscribers, and so are multicast to all subscribers' printers and the appropriate page servers.
The netpage publication server optimizes the segmentation of document content into pointcasts and multicasts. After receiving the pointcast of a document's page layouts, the printer knows which multicasts, if any, to listen to.
Once the printer has received the complete page layouts and objects that define the document to be printed, it can print the document.
The printer rasterizes and prints odd and even pages simultaneously on both sides of the sheet. It contains duplexed print engine controllers
760 and print engines utilizing Memjet™ printheads
350 for this purpose.
The printing process consists of two decoupled stages: rasterization of page descriptions, and expansion and printing of page images. The raster image processor (RIP) consists of one or more standard DSPs
757 running in parallel. The duplexed print engine controllers consist of custom processors which expand, dither and print page images in real time, synchronized with the operation of the printheads in the print engines.
Printers not enabled for invisible IR printing have the option to print tags using IR-absorptive black ink, although this restricts tags to otherwise empty areas of the page.
Although such pages have more limited functionality than invisible IR-printed pages, they are still classed as netpages.
A normal netpage printer prints netpages on sheets of paper. More specialized netpage printers may print onto more specialized surfaces, such as globes or sheets of plastics. Each printer supports at least one surface type, and supports at least one tag tiling scheme, and hence tag map, for each surface type. The tag map
811 which describes the tag tiling scheme actually used to print a document becomes associated with that document so that the document's tags can be correctly interpreted.
FIG. 2 shows the netpage printer class diagram, reflecting printer-related information maintained by a registration server
11 on the netpage network.
A preferred embodiment of the netpage printer is described in greater detail in Section 6 below, with reference to FIGS. 11 to 16.
1.5.1 Memjet™ Printheads
The netpage system can operate using printers made with a wide range of digital printing technologies, including thermal inkjet, piezoelectric inkjet, laser electrophotographic, and others. However, for wide consumer acceptance, it is desirable that a netpage printer have the following characteristics:
- photographic quality color printing
- high
