Edge delta runlength (EDRL) data stream decoder for bi-level graphics

• US 20050083358A1
• Filed: 12/06/2004
• Published: 04/21/2005
• Est. Priority Date: 11/09/1998
• Status: Active Grant

• Current Assignee: Memjet Technology Ltd. (Memjet Limited)
• Original Assignee: Silverbrook Research Pty Limited
• Inventors: Silverbrook, Kia, Lapstun, Paul, Walmsley, Simon Robert
• Granted Patent: US 7,284,805 B2
• Time in Patent Office: Days
• US Class Current: 347/5
• CPC Class Codes: B41J 11/008 Controlling printhead for accurately positioning print image on printing material, e.g. with the intention to control the width of margins
• CPC Class Codes: B41J 11/42 Controlling printing material conveyance for accurate alignment of the printing material with the printhead; Print registering
• CPC Class Codes: B41J 13/103 for the sheet feeding section
• CPC Class Codes: B41J 2/0452 reducing demand in current or voltage
• CPC Class Codes: B41J 2/04528 aiming at warming up the head
• CPC Class Codes: B41J 2/04543 Block driving
• CPC Class Codes: B41J 2/04551 using several operating modes
• CPC Class Codes: B41J 2/04563 detecting head temperature; Ink temperature
• CPC Class Codes: B41J 2/0457 Power supply level being detected or varied
• CPC Class Codes: B41J 2/0458 controlling heads based on heating elements forming bubbles
• CPC Class Codes: B41J 2/04586 controlling heads of a type not covered by groups B41J2/04575 - B41J2/04585, or of an undefined type
• CPC Class Codes: B41J 2/04591 Width of the driving signal being adjusted
• CPC Class Codes: B41J 2/04596 Non-ejecting pulses
• CPC Class Codes: B41J 2/155 for line printing
• CPC Class Codes: B41J 2/16505 Caps, spittoons or covers for cleaning or preventing drying out
• CPC Class Codes: B41J 2/16511 Constructions for cap positioning B41J2/16547 takes precedence
• CPC Class Codes: B41J 2/16585 for paper-width or non-reciprocating print heads
• CPC Class Codes: B41J 2/175 Ink supply systems ; Circuit parts therefor
• CPC Class Codes: B41J 2/17566 Ink level or ink residue control
• CPC Class Codes: B41J 2/515 line printer type
• CPC Class Codes: B41J 2002/17569 : based on the amount printed or to be printed
• CPC Class Codes: B41J 2202/17 : Readable information on the head
• CPC Class Codes: B41J 2202/20 : Modules
• CPC Class Codes: B41J 2202/21 : Line printing
• CPC Class Codes: B41J 25/34 : Bodily-changeable print heads or carriages
• CPC Class Codes: B41J 29/02 : Framework
• CPC Class Codes: B41J 29/13 : Cases or covers
• CPC Class Codes: B41J 29/38 : Drives, motors, controls or automatic cut-off devices for the entire printing mechanism
• CPC Class Codes: G03G 15/0863 : provided with identifying means or means for storing process- or use parameters, e.g. an electronic memory
• CPC Class Codes: G03G 15/55 : Self-diagnostics; Malfunction or lifetime display
• CPC Class Codes: G03G 2215/0697 : being an electronically readable memory
• CPC Class Codes: G03G 2221/1823 : Cartridges having electronically readable memory
• CPC Class Codes: G06F 3/1213 : at an intermediate node or at the final node
• CPC Class Codes: G06F 3/1214 : at the submitting node
• CPC Class Codes: G06F 3/122 : with regard to computing resources, e.g. memory, CPU
• CPC Class Codes: G06F 3/1247 : by conversion to printer ready format
• CPC Class Codes: G06F 3/1284 : Local printer device
• CPC Class Codes: G06K 15/00 : Arrangements for producing a permanent visual presentation of the output data , e.g. computer output printersprinting or plotting combined with another operation, e.g. with conveying, G06K17/00
• CPC Class Codes: G06K 15/02 : using printers
• CPC Class Codes: G06K 15/102 : using ink jet print heads
• CPC Class Codes: G06K 15/1814 : including print-ready data, i.e. data already matched to the printing process
• CPC Class Codes: G06K 15/1815 : Receiving print data in mixed format
• CPC Class Codes: G06K 15/1817 : Buffers
• CPC Class Codes: G06K 15/1852 : involving combining data of different types
• CPC Class Codes: G06K 15/1855 : Combining raster data and graphic primitives
• CPC Class Codes: G06K 15/1856 : characterized by its workflow
• CPC Class Codes: G06K 15/1857 : involving parallel processing in the same printing apparatus
• CPC Class Codes: G06K 2215/0094 : Colour printing
• CPC Class Codes: H04N 1/32561 : using a programmed control device, e.g. a microprocessor
• CPC Class Codes: H04N 1/32587 : Controller
• CPC Class Codes: H04N 1/32598 : Bus based systems
• CPC Class Codes: H04N 1/3871 : the composed originals being of different kinds, e.g. low- and high-resolution originals
• CPC Class Codes: H04N 1/40 : Picture signal circuits H04N1/387 takes precedence
• CPC Class Codes: H04N 1/41 : Bandwidth or redundancy reduction by scanning H04N1/17 ; methods or arrangements for coding, decoding, compressing or decompressing digital video signals H04N19/00
• CPC Class Codes: H04N 1/60 : Colour correction or control H04N1/54 takes precedence
• CPC Class Codes: H04N 1/642 : Adapting to different types of images, e.g. characters, graphs, black and white image portions

Abstract

An edge delta run length (EDRL) expander circuit includes an EDRL stream decoder. The symbols comprising EDRL streams are preferably entropy encoded. In order to maintain symbol alignment the EDRL stream decoder includes a barrel shifter that receives the encoded data stream and is controlled by a feedback loop indicating symbol code length. In one embodiment the feedback loop includes a modulo-n adder, where n is the length of an input code word bit pattern of the data stream.

Claims

1. An expander circuit to process an edge delta runlength (EDRL) encoded data stream of codewords to produce image line data, including:

an EDRL stream decoder responsive to the encoded data stream including,

a barrel shifter,

a decoder coupled to the barrel shifter,

an EDRL state machine responsive to the decoder and configured to produce data indicating codeword length; and

a feedback loop responsive to the data indicating code length and arranged to control operation of the barrel shifter.

2. An expander circuit according to claim 1, wherein the EDRL encoded data stream is entropy coded.

3. An expander circuit according to claim 2, wherein the feedback loop includes a bit offset circuit arranged to vary shifting of the barrel shifter on the basis of the data indicating code length.

4. An expander circuit according to claim 3, wherein the bit offset circuit controls the barrel shifter so that an edge of the barrel shifter storing a most significant bit is aligned to a codeword boundary of the encoded data stream.

5. An expander circuit according to claim 4, wherein the bit offset circuit is arranged to perform addition of a current codeword bit offset with a newly generated codeword bit offset from the EDRL state machine.

6. An expander circuit according to claim 5, wherein the bit offset circuit performs modulo-n addition where n is the length of an input codeword bit pattern of said data stream.

7. A printer including an expander circuit according to claim 1.

8. A printer of a type having a micromechanical pagewidth printhead including an expander circuit according to claim 6.