Abstract:
A multiple font management system and method in a printing device for activating multiple fonts is provided for enabling base font localization and font patching for print jobs to reduce the need to upload entire fonts in order to provide localized receipts or to provide corrections to partially-corrupted font tables. A font access level stores locations of activated base, localization and patch fonts and are referenced in an access order during character retrieval so as to apply retrieval priority to patches and localizations. A font storage level maintains multiple tier character indices for referencing character shape data in order to provide faster character searching through each of the multiple activated fonts than a single-level index.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a divisional of U.S. patent application Ser. No. 10/949,870 filed Sep. 24, 2004. The contents of this application are incorporated herein by reference in their entirety. 
    
    
     BACKGROUND 
     1. Field of the Invention 
     The present invention relates generally to printing devices and in particular, to a method and system for managing multiple fonts in a printing device. 
     2. Background of the Invention 
     Stand-alone electronic cash registers including payment card readers and receipt printers have been used for years in stores, retail outlets and service outlets to facilitate the completion of cash, cheque, credit card or debit card transactions for the purchase of goods and/or services. With the advent of sophisticated and inexpensive computing equipment, input devices and secure communication networks, point-of-sale (POS) stations have become an increasingly popular alternative. 
     POS stations typically include a host device and a plurality of interchangeable peripherals connected to the host device. The host device and peripherals are easily integrated allowing the configuration of POS stations to be modified to meet changing needs. This has been another factor leading to their widespread acceptance. The host device is commonly in the form of a personal computer. The peripherals often include a keyboard, a display screen, a cash drawer, a printing device, a payment card reader and a barcode reader. In some cases, a touch-sensitive display screen is used instead of separate keyboard and display screen peripherals. 
     As is well known, the host device communicates with the peripherals and executes software to allow product and/or service transactions to be completed. When payment is effected using a debit or credit card, the host device establishes a connection to the appropriate financial institution over an information network so that approval for the transaction may be obtained. Upon completion of any transaction, the host device signals the printing device causing the printing device to generate a transaction receipt and a possibly signing receipt, if payment is made using a credit card. 
     In larger stores, retail outlets and service outlets, POS stations are typically linked via a local area network and communicate with a backend computing device that maintains a database for transaction, inventory, accounting, sales, tax, etc. information. Transaction data received by each of the POS stations is conveyed to the backend computing device for storage in the database allowing all transaction data to be stored in a common location. Collectively storing all transaction data in one common location allows retailers to track, account for and maintain inventory, collected taxes and pricing information. Also, by linking the POS stations, updates relating to sales on products and/or services, tax, etc. can be communicated to each POS station over the local area network avoiding the need to update the POS stations one at a time. 
     Printing devices commonly used in POS stations comprise a printer having a slot for receiving a separate printer interface that controls communications between the host device and the printer. The printer interface is primarily selected based on the communication protocol used by the host device thereby to ensure hardware compatibility between the host device and the printer. For example, hardware compatibility may be achieved by installing a serial, parallel, Ethernet or USB interface. As the printer interface can be readily changed, the printer is not limited for use with any particular communication protocol but rather can be used in many different communication protocol environments simply by replacing the printer interface. The printer interface may also be selected to enhance functionality of the printer such as by adding supplemental fonts or by emulating one or more other printer models. 
     The printer interface and the printer are typically preloaded with firmware although the printing device may receive updated printer firmware from the host device to replace or patch the existing printer firmware. The printer firmware stored in the printer interface is in turn conveyed to the printer for storage therein. The printer firmware typically includes a boot file, a main firmware file and one or more font files. The boot file is executed by the printer during initialization to place the printer into a ready operating state. The main firmware and font files are executed during normal operation of the printer to allow the printer to respond to print commands received from the host device via the printer interface so that appropriate transaction receipts can be printed. A font encompasses a specific set of characters that are designed to have a certain look or style. The font file typically contains glyph or shape data for each character in the font file character sets. 
     In many instances it is desired to update the printer firmware stored in the printer to allow the printing device to print receipts in different formats and/or languages, to support additional functionality and/or to enhance printer performance. For instance, a customer from a particular locale may be more comfortable reading a receipt with one or more characters in the customer&#39;s language localized according to the customer&#39;s locale. In order to achieve this, it is known to store an entire localized font file containing mostly the standard language characters and select modified characters on the printing device, and to access all characters for the receipt from the localized font file. However, the printing device must have enough memory to store the additional localized font file, or replace the original font file effectively limiting receipt printing to localized characters. Furthermore, due to font file sizes, it can be time consuming to download an entire font file. 
     The same disadvantages accrue when errors are discovered in one or more characters of a font, because known methods involve replacing the font file containing the errors with a complete, corrected font file. 
     As a result, a number of techniques for managing multiple fonts in a printing device have been considered. For example, U.S. Pat. No. 4,353,653 to Zimmerman discloses a printer subsystem for storing a large number of compressed font files that is intended to increase the number of fonts available to a user and increase font use flexibility by enabling rapid switch-over between fonts. The printer is loaded with a base font image set that can be replaced by other font images. At column 36 and FIG. 58, Zimmerman discloses storage of fonts and font reference data in groups of tables. The tables include a Multinational Master Table for storing multiple character images, a Major Country Table for storing changes to the Multinational Master Table, and a Modification to Master Table for storing moves of characters in the master table from one location to another. A register stores bits for signalling whether the Multinational master table is to be overlaid with a major country entry or a modification country entry. Zimmerman shows an example of loading a font from a different country into RAM for use by the printer in response to receipt of a control sequence. 
     U.S. Patent Application Publication No. 2002/0099867 to Wilkinson et al. discloses a portable operating environment for information devices. A primary character subset, along with characters from secondary subsets are defined (font extensions) for localization purposes (see paragraphs [0084] to [0087]). A font extension may be linked to several font instances, and loaded on demand. 
     Although the above references describe multiple-font management methods, as will be appreciated, they merely enable a print device to effectively extend a font&#39;s character set. As a result, a host device must be aware of the characters available in a particular extension font and specify the correct font in print command sequences. The references do not address the problem of correcting or localizing characters in an existing font. 
     It is therefore an object of the invention to provide a novel method of managing multiple fonts in a printing device, and a system implementing the method. 
     SUMMARY OF THE INVENTION 
     Accordingly, in one aspect of the invention there is provided a method of managing multiple fonts in a printing device comprising activating a first font by storing the location of the first font in a first font access variable being first in a font access order; and activating a second font by storing the location of the second font in a second font access variable being second in the font access order. Subsequent accesses to characters at the font locations is conducted in accordance with the access order of the font access variables. 
     By providing a method of managing multiple fonts in which multiple fonts may be activated, a localization font or font patch containing only localized characters or patched characters, rather than an entire character set, may be downloaded to the printing device and subsequently accessed by a host device during a print job without the host device specifying a change in font. 
     In another aspect of the invention there is provided a method of accessing a character in a printing device in which multiple fonts are activated. The method comprises searching a first font being first in a font access order for the character; and in the event that the character is not in the first font, automatically searching a second font being second in the font access order for the character. 
     Preferably, additional fonts being third and fourth in the font access order may be activated to provide additional localization or patching flexibility. 
     In yet another aspect of the invention there is provided a system for managing multiple fonts in a printing device. The system comprises a font access level having memory for storing font locations of activated fonts according to a font access order, and a microprocessor readable access program for accessing characters in the activated fonts in the font access order. The system also comprises a font storage level having memory for storing the activated fonts. 
     The font table memory comprises font tables which each preferably have a font header, character shape data and a multiple-tier character index for facilitating character searches. 
     The font management method and system provides advantages in that localized fonts and font patches can be provided to a printing device without the lengthy and memory-intensive download of an entire font set. Thus, character adjustments can be provided to a printing device in a shorter period of time and with less memory than prior art methods. When character shape data is required for a print job, the preferred multiple-tier character index in font tables is space-efficient and also increases lookup speed. This increase in lookup speed provides the advantage that in the event that multiple fonts must each be searched for a particular character, the lookup speed is faster than if each font had a single-tier character index with all entries. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Embodiments will now be described more fully with reference to the accompanying drawings in which: 
         FIG. 1  is a schematic block diagram of a point-of-sale station including a printing device; 
         FIG. 2  is a schematic block diagram of the printing device of  FIG. 1 ; 
         FIG. 3  is a schematic block diagram of a multiple-level font management system on the printing device including a font access level, a font listing level and a font table level; 
         FIG. 4  is a schematic block diagram of data maintained by the font access level of  FIG. 3 ; 
         FIG. 5  is a schematic block diagram of data maintained by the font listing level of  FIG. 3 ; 
         FIG. 6  is a schematic block diagram of data maintained by the font table level of  FIG. 3 , including a font header, a character index and character shape data; 
         FIG. 7  is a schematic block diagram of a multiple-tier index and character segments of which the character index of  FIG. 6  is comprised; 
         FIG. 8  is a flowchart showing the method of font activation used with the system of  FIG. 3 ; and 
         FIG. 9  is a flowchart showing the method of character retrieval used with the system of  FIG. 3 . 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Turning now to  FIG. 1 , a point-of-sale (POS) station is shown and is generally identified by reference numeral  10 . As can be seen, POS station  10  includes a microprocessor-based host device  12  in the form of a personal computer that communicates with a plurality of peripherals generally identified by reference numeral  14  and with a database  16  storing transaction, inventory, pricing, tax and accounting information. In this example, peripherals  14  include a keyboard  18 , a touch-sensitive display screen  20 , a payment card scanner  22 , a cash drawer  24 , a printing device  26  and a barcode scanner  28 . Host device  12  also communicates with financial institutions (not shown) such as banks and credit card companies over one or more information networks generally identified by reference numeral  30 . 
     Printing device  26  is best illustrated in  FIG. 2  and includes a printer interface  50  and a printer  52 . Printer interface  50  comprises a microcontroller  60 , a host interface board  62 , a printer interface board  64 , RAM  65  and non-volatile flash NAND memory  66 . Printer  52  comprises a microcontroller  70 , a communications channel interface board  72 , a printer control mechanism  74  and non-volatile flash NAND memory  76 . For example, the printer interface  50  may be of the type sold by EPSON under model No. UB-EML and printer may be of the type sold by EPSON under model No. TM-U200. 
     The non-volatile memory  66  stores printer interface firmware that is executed by the microcontroller  60  during initialization and operation of the printing device  26  to permit communications between the host device  12  and the printer  52  and optionally to enhance operation of the printer by storing supplemental font files that allow the printer to print different font-type characters and/or emulation files that allow the printer to emulate one or more other printer models. 
       FIG. 3  is a schematic block diagram of the font management system of the invention, generally designated by reference numeral  96 . Font management system  96  is implemented in non-volatile memory  66  on printer interface  50 , and comprises a font access level  100  and a font storage level  200 . Font access level  100  provides access to multiple activated fonts and is used by printer interface  50  during font selection and activation, and accessing character data in activated fonts. Basic font reading, writing and deletion is provided by font storage section  200 , which comprises both a font listing level  220  and a font table level  240 . 
     Font listing level  220  of font storage level  200  stores locations of fonts in font table level  240  and is used by printer interface  50  when fonts are selected, activated and downloaded from host device  12  and deleted from font storage section  200 . 
     Font table level  240 , comprising font table storage  242  and NAND Sector Processing Data  270 , stores fonts and sector processing data and is used by printer interface  50  when fonts are selected, activated, downloaded from host device  12  and deleted from font storage section  200 . Font table level  240  is also used during character access such as character searches and character shape data retrieval. 
     The features of the system shown in  FIG. 3  that support the font selection, activation, and character access processes will now be described. 
       FIG. 4  is a schematic block diagram showing font access level  100  in further detail. Font access level  100  employs RAM  65  of printer interface  50  to store locations in font table level  240  of activated fonts for use during character access. As illustrated in  FIG. 4 , up to four fonts may be activated by storage of their respective locations in variables  102 ,  104 ,  106  and  108  of RAM  65 . Furthermore, variables  102 ,  104 ,  106  and  108  are subject to an access order during character access. As such, in terms of font access order, variable  108  is first, variable  106  is second, variable  104  is third and variable  102  is fourth. 
     Access to variables  102 ,  104 ,  106  and  108  according to the access order is controlled by microprocessor-readable program code handled by font access level  100  which is part of the printer interface firmware. The method executed by the program code will be described below. 
       FIG. 5  is a schematic block diagram showing font listing level  220  in further detail. Font listing level  200  comprises a variable  222  for storing the number of fonts in the font table level, a number of variables  224  (shown as  224   a ,  224   b  and  224   c  etc.) for storing respective locations of the fonts, and a number of variables  226  (shown as  226   a ,  226   b  and  226   c ) for storing the fonts&#39; respective availability statuses. A font&#39;s availability status can have one of the following values: “downloading”, “complete” or “deleting”. The availability status is an indicator as to whether a font is presently unavailable because it is being deleted or because it is still being downloaded. 
       FIG. 6  is a schematic block diagram showing font table level  240  in further detail. Font table level  240  comprises font table storage  242  and NAND sector processing data  270 . Each font table  243  (shown as  243   a ,  243   b  etc.) in font table storage  242  comprises a font header  244 , a character index  246  and character shape data  266 . Font header  244  contains a font ID and a patch flag indicating whether the font has patch or non-patch status. 
       FIG. 7  is a conceptual block diagram showing character index index  246  of font table  243  in further detail. Character index  246  is a multi-tier index have sub-indices for which portions of a 21-bit Unicode character code  248  are used as keys. In particular, portion  250  of character code  248  is a key for subindex  252 , portion  254  is a key for subindex  256 , portion  258  is a key for subindex  260  and portion  262  is a key for character segment index  262 . 
     The multiple-tier character index  246  enables font access level  100  to more quickly search a font to determine whether the character data corresponding to character code  248  exists in that font, than if the character index were a single tier requiring a serial search through every single font entry. Another key advantage of the multiple-tier index is that the index is much smaller than a single-tier because index entries for which there is no character data need not be stored. 
     The above-described system for managing multiple activated fonts each having a respective position in an access order is very flexible. This system is used to provide localized characters and font patches to correct character errors in fonts stored in font storage level  200 , without the limitation of requiring complete character sets to be downloaded to printer interface  50 . For the purposes of the following description, a base font is defined generally as a complete character set for printing in a language or languages. A localization font contains a subset of replacement characters for the base font that provide character adjustments suited for a particular locale using the language or languages. The base and localization fonts are selected prior to font activation by a user or automatically by host device  12  by providing to printer interface  50  a base font ID and a localization font ID. Upon receipt of the font IDs, font access level  100  initiates activation of the base and localization fonts. Font access level  100  also initiates activation of patch fonts for each of the base and localization fonts, as will be described below. 
     With reference to  FIG. 8 , during font activation, host device  12  selects a base font and a localization font and sends the base font ID and localization font ID to printer interface  50 . Font access level  100  receives the base and localization font IDs (step  300 ). In response to receipt of the font IDs, font access level  100  contacts font listing level  220  for the number and locations in font table memory  240  of accessible fonts (step  302 ). 
     Font access level  100  receives from font listing level  220  the number of font locations from variable  222 , all font locations from variables  224  and their respective availability statuses from variables  226  (step  304 ). 
     To retrieve the base font location, at each font location in variables  224  having availability statuses in variables  226  of “complete”, font access level  100  searches font table memory  240  for a font header  244  containing the base font ID and having a non-patch status (step  306 ). When a match is found (step  308 ), the font location corresponding to the match is stored in font access variable  102 , corresponding to the fourth access variable in the access order (step  312 ). If a font table having a font header  244  containing the base font ID and having a non-patch status is not found, an error is sent to host device  12  (step  310 ). 
     To retrieve the base font patch location (if any), at each font location in variables  224  having availability statuses in variables  226  of “complete”, font access level  100  searches font table memory  240  for a font header  244  containing the base font ID and having a patch status (step  314 ). If a match is found, the font location corresponding to the match is stored in font access variable  104 , corresponding to the third access variable in the access order (step  318 ). If no match is found, then a base font patch corresponding to the base font ID is assumed not to be stored in font table memory  240 . 
     To retrieve the localization font location, at each font location in memory locations  124  having availability statuses in variables  226  of “complete”, font access level  100  searches font table memory  240  for a font header  244  containing the localization font ID and having a non-patch status (step  320 ). If a match is found (step  322 ), the font location corresponding to the match is stored in font access variable  106 , corresponding to the second access variable in the access order (step  326 ). If a font table having a font header  244  containing the localization font ID and having a non-patch status is not found, an error is sent to host device  12  (step  324 ). 
     To retrieve the localization font patch location (if any), at each font location in memory locations  224  having availability statuses in variables  226  of “complete”, font access level  100  searches font table memory  240  for a font header  244  containing the localization font ID and having a patch status (step  328 ). If a match is found (step  330 ), the font location corresponding to the match is stored in font access variable  108 , corresponding to the first access variable in the access order (step  332 ). If no match is found, then a localization font patch corresponding to the localization font ID is assumed not to be stored in font table memory  240 . 
     Activation of fonts by population of variables  102 ,  104 ,  106  and  108  in font access level  100  is controlled by microprocessor-readable program code handling font listing level  220  and font access level  100 . 
     After the locations have been stored, activation is considered complete and subsequent access to character data will use the activated fonts as described below. As described in general above, once the fonts have been activated by populating the variables  102 ,  104 ,  106  and  108  in printer interface RAM  65 , a subsequent access to character data is carried out in accordance with the access order of memory areas  102 ,  104 ,  106  and  108 . 
     With reference to  FIG. 9 , during character access for a print job, font access level  100  receives a character code  248  (step  400 ). Font access level  100  then retrieves a first location from the first variable  108  in the font access order (step  402 ). The first location corresponds to the localization font patch. Using the first location, a search is conducted using the multiple-tier character index  246  in the font table  243  at the first location (step  404 ). If the character is found in the font table at the first location (step  406 ) then the character shape data from the font table at the first location is sent to the printer control mechanism  76  for output (step  407 ). 
     If the character is not yet found, font access level  100  then retrieves a second location from the second variable  106  in the font access order (step  410 ). The second location corresponds to the localization font. Using the second location, a search is conducted using the multiple-tier character index  246  in the font table  243  at the second location (step  412 ). If the character is found in the font table at the second location (step  414 ) then the character shape data from the font table at the second location is sent to the printer control mechanism  76  for output (step  415 ). 
     If the character is not yet found, font access level  100  then retrieves a third location from the third variable  104  in the font access order (step  416 ). The third location corresponds to the base font patch. Using the third location, a search is conducted using the multiple-tier character index  246  in the font table  243  at the third location (step  418 ). If the character is found in the font table at the third location (step  420 ) then the character shape data from the font table at the third location is sent to the printer control mechanism  76  for output (step  421 ). 
     If the character is still not yet found, font access level  100  then retrieves a fourth location from the fourth variable  104  in the font access order (step  422 ). The fourth location corresponds to the base font. Using the fourth location, a search is conducted using the multiple-tier character index  246  in the font table  243  at the fourth location (step  424 ). If the character is found in the font table at the fourth location (step  426 ) then the character shape data from the font table at the fourth location is sent to the printer control mechanism  76  for output (step  427 ). 
     If, at this stage, the character has not yet been found, either an error is returned to the host device  12  or shape data for a replacement character is sent to the printer control mechanism  76  (step  428 ). Other similar remedies for an unfound character would occur to one of ordinary skill in the art. 
     It will be understood that font access level  100  can provide from one to four activated fonts. As such, should solely variable  108  be populated with a font location, character searches are made only in that font. Should variables  108  and  106  be populated with respective font locations, a character search is made first in the font whose location is stored in variable  108  and if the character is not found in the first font then a character search is carried out next in the font whose location is stored in variable  106 . If variable  104  is populated with a font location, the character search may continue in that font if the character has not yet been found. The same is true of a font whose location is stored in variable  102 . 
     With reference again to  FIG. 7 , navigation of the multiple-tier character index  246  during character access will now be described. 
     The first five bits  250  (bits  20 - 16 ) in character code  248  are “00000”, which key to position “[0]” in subindex  252 . The value at position “[0]” in subindex  252  is a pointer to a particular area of subindex  256 . The next eight bits  254  (bits  15 - 8 ) in character code  248  are “00000100”, which key to position “[4]” in the particular area of subindex  256 . The value at position “[4]” in the particular area of subindex  256  is a pointer to a particular area of subindex  260 . The next five bits (bits  7 - 3 ) in character code  248  are “00011”, which key to position “[3]” in the particular area of subindex  260 . The value at position “[3]” in the particular area of subindex  260  is a pointer to a particular character segment in character segment index  262 . The next three bits (bits  2 - 0 ) in character code  248  are “010”, which key to position “Chr[2]” in the particular character segment in character segment index  262 . The data immediately following position “Chr[2]” in the character segment index  262  is the desired character&#39;s shape data. 
     As described above, using a multi-tier character index  246 , font access level  100  can quickly determine that character data corresponding to character code  248  does not exist in an activated font, and can thereby search another activated font whose location is stored in the font access variable next in the access order. While also being efficient, the multiple-tier index is compact. 
     Although specific reference is made to a printer used in a POS station, those of skill in the art will appreciate that this is for ease of illustration. The multiple font management method is suitable for use with virtually any type of printer such as for example dot matrix printers, thermal printers, ink jet printers, laser printer etc. 
     Furthermore, although the preferred embodiment of the multiple font management system of the invention has been described as being resident on printer interface board  50 , it could be implemented entirely on printer  52 , with only minor modifications. As a further alternative, font access level  100  could be implemented on printer interface board  50 , while font storage level  200  could be implemented on printer  52 . As such, the appended claims make reference to a printing device, rather than solely a printer interface, or solely a printer, in order to refer to the variations and alternatives described above. 
     Although embodiments have been described, those of skill in the art will appreciate that the variations and modifications may be made without departing from the spirit and scope of the invention as defined by the appended claims.