WO2014029418A1

WO2014029418A1 - Color registration calibration method for a printer apparatus

Info

Publication number: WO2014029418A1
Application number: PCT/EP2012/066209
Authority: WO
Inventors: Tsafrir YEDID AM; Tair ATZMON; Dani Sagi; Eitan Kichli; Ran Waidman
Original assignee: Hewlett-Packard Indigo Bv
Priority date: 2012-08-20
Filing date: 2012-08-20
Publication date: 2014-02-27

Abstract

Printer apparatus including a controller to control printing on at least one portion of a substrate at a predetermined position while printing a print job on the substrate, receive image data including the at least one printed portion of the substrate, determine the position of the at least one printed portion of the substrate from the image data, and generate calibration data by comparing the determined position of the at least one portion with the predetermined position of the at least one portion.

Description

TITLE

COLOR REGISTRATION CALIBRATION METHOD FOR A PRINTER APPARATUS

BACKGROUND

Some printer apparatus include a photo imaging roller for receiving light from a writing head and a printing fluid (such as ink or toner) for forming an image on the photo imaging roller. The image may then be transferred to a blanket roller from the photo imaging roller and subsequently to a substrate (such as paper). The printed substrate may then be output from the printer apparatus for collection.

BRIEF DESCRIPTION

Reference will now be made by way of example only to the accompanying drawings in which:

Fig. 1 illustrates a schematic side view diagram of a printer apparatus according to an example;

Fig. 2 illustrates a schematic plan view diagram of the printer apparatus illustrated in fig. 1 ; and Fig. 3 illustrates a flow diagram of a method of calibrating printer apparatus according to an example.

DETAILED DESCRIPTION Fig. 1 illustrates a schematic side view diagram of a printer apparatus 10 including a controller 12, a writing head 14, a photo imaging roller 16, at least one printing fluid roller 18, a blanket roller 20, an impression drum 22 and at least one sensor 26. The printer apparatus 10 is arranged to receive a substrate 24, apply printing fluid to at least one surface of the substrate 24, and output the printed substrate 24. The printer apparatus 10 may be a printing device or may be a module of a printing device (where 'module' refers to a unit or apparatus that excludes certain parts/components that would be added by an end manufacturer or a user).

The controller 12 is arranged to control the operation of the printer apparatus 10 and may control the operation of the writing head 14, the photo imaging roller 16, the at least one printing fluid roller 18, the blanket roller 20, the impression drum 24 and the at least one sensor 26 (control lines from the controller 12 are not illustrated in fig. 1 to maintain clarity). The implementation of the controller 12 can be in hardware alone (for example, a circuit, a processor and so on), have certain aspects in software including firmware alone or can be a combination of hardware and software (including firmware).

The controller 12 may be implemented using instructions that enable hardware functionality, for example, by using executable computer program instructions in a general-purpose or special-purpose processor 28 that may be stored on a computer readable storage medium 30 (disk, memory and so on) to be executed by such a processor 28.

The processor 28 is configured to read from and write to the memory 30. The processor 28 may also comprise an output interface via which data and/or commands are output by the processor 28 and an input interface via which data and/or commands are input to the processor 28.

The memory 30 stores a computer program 32 comprising computer program instructions that control the operation of the printer apparatus 10 when loaded into the processor 28. The computer program instructions 32 provide the logic and routines that enables the printer apparatus 10 to perform the method illustrated in Fig. 3. The processor 28 by reading the memory 30 is able to load and execute the computer program 32. The memory 30 also stores calibration data 33 that may be used by the controller 12 to control the writing head 14, the photo imaging roller 16, the at least one printing fluid roller 18, the blanket roller 20, the impression drum 24 so that printing fluid is deposited accurately on the substrate 24. The calibration data 33 is discussed in greater detail in the following paragraphs.

The computer program 32 may arrive at the printer apparatus 10 via any suitable delivery mechanism 34. The delivery mechanism 34 may be, for example, a non-transitory computer-readable storage medium, a computer program product, a memory device, a record medium such as a compact disc read-only memory (CD-ROM) or digital versatile disc (DVD), an article of manufacture that tangibly embodies the computer program 32. The delivery mechanism 34 may be a signal configured to reliably transfer the computer program 32. The printer apparatus 10 may propagate or transmit the computer program 32 as a computer data signal.

Although the memory 30 is illustrated as a single component it may be implemented as one or more separate components some or all of which may be integrated/removable and/or may provide permanent/semi-permanent/ dynamic/cached storage.

References to 'computer-readable storage medium', 'computer program product', 'tangibly embodied computer program' etc. or a 'controller', 'computer', 'processor' etc. should be understood to encompass not only computers having different architectures such as single /multi- processor architectures and sequential (Von Neumann)/parallel architectures but also specialized circuits such as field-programmable gate arrays (FPGA), application specific circuits (ASIC), signal processing devices and other processing circuitry. References to computer program, instructions, code etc. should be understood to encompass software for a programmable processor or firmware such as, for example, the programmable content of a hardware device whether instructions for a processor, or configuration settings for a fixed-function device, gate array or programmable logic device etc. As used in this application, the term 'circuitry' refers to all of the following:

(a) hardware-only circuit implementations (such as implementations in only analog and/or digital circuitry) and

(b) to combinations of circuits and software (and/or firmware), such as (as applicable): (i) to a combination of processor(s) or (ii) to portions of processor(s)/software (including digital signal processor(s)), software, and memory(ies) that work together to cause an apparatus to perform various functions) and

(c) to circuits, such as a microprocessor(s) or a portion of a microprocessor(s), that require software or firmware for operation, even if the software or firmware is not physically present.

This definition of 'circuitry' applies to all uses of this term in this application, including in any claims. As a further example, as used in this application, the term "circuitry" would also cover an implementation of merely a processor (or multiple processors) or portion of a processor and its (or their) accompanying software and/or firmware.

The controller 12 is arranged to control the writing head 14 to provide light to the photo imaging roller 16 to distribute charge on the photo imaging roller 16. For example, the controller 12 may read image data stored on the memory 30 and control the writing head 14 to provide light to the photo imaging roller 16 so that the distributed charge on the photo imaging roller 16 corresponds to the image in the image data. The controller 12 is arranged to control the at least one printing fluid roller 18 to provide printing fluid (such as ink or toner) to the photo imaging roller 16. The printing fluid is electrically charged and fixes to the photo imaging roller 16 to form the image in the image data. Where the printer apparatus 10 includes a plurality of printing fluid rollers 18 for different colours of printing fluid, the controller 12 may control the plurality of printing fluid rollers 18 so that a single colour is applied for each revolution of the photo imaging roller 16 (i.e. the image is built up one colour at a time on the photo imaging roller 16).

The blanket roller 20 is arranged to receive the printing fluid from the photo imaging roller 16 and consequently, the image is transferred from the photo imaging roller 16 to the blanket roller 20. The blanket roller 20 forms a nip with the impression drum 22 and as the substrate 24 moves through the nip formed between the blanket roller 20 and the impression drum 22, the printing fluid (and therefore the image) is transferred from the blanket roller 20 to the substrate 24. The printed substrate 24 may then be output from the printer apparatus 10 via the at least one sensor 26.

The at least one sensor 26 may be any suitable sensor for obtaining images of the printed substrate 24 and may be, for example, a charge coupled device (CCD) sensor or a complementary metal oxide semiconductor (CMOS) sensor. The at least one sensor 26 is arranged to capture one or more images of the printed substrate 24 after the printed substrate 24 has passed through the nip formed between the blanket roller 20 and the impression drum 22. The controller 12 is arranged to receive image data from the at least one sensor 26.

As described above, the controller 12 uses the calibration data 33 to control the deposition of printing fluid on the substrate 24. For example, the calibration data 33 may be used by the controller 12 to control the printing fluid rollers 18 to provide printing fluid to the photo imaging roller 16 at a particular time and at a particular location or locations that will result in the printing fluid being deposited at a desired position on the substrate 24. In some examples, the calibration data 33 may be initially generated by calibration software (which may be referred to as a colour plain registration (CPR) wizard) that uses data from a static in line scanner (ILS) of the printer apparatus 10. The horizontal colour plain registration (HCPR) which is measured per y (i.e. vertical dimension on the substrate 24) and x (i.e. horizontal dimension on the substrate 24) locations is calculated:

HCPR(x, y) = ∑_{l+ l} c_tJy^lxl) or:

(1 χ⁸)·

Fig. 2 illustrates a schematic plan view diagram of the printer apparatus 10 illustrated in fig. 1 . In more detail, fig. 2 illustrates the blanket roller 20, the substrate 24, a first sensor 261 and a second sensor 262 (corresponding to the at least one sensor 26) of the printer apparatus 10.

In operation, the blanket roller 20 rotates and moves the substrate 24 in the direction of arrow 40. The substrate 24 includes a printed image 42 which was transferred from the blanket roller 20 to a central portion of the substrate 24. The printed image 42 does not extend into a left hand margin 36 of the substrate 24 or into a right hand margin 38 of the substrate 24. The printed image 42 forms at least a part of a print job and may include, for example, text, graphics and/or pictures. The left and right hand margins 36, 38 include printed portions 44 that were printed on the substrate 24 at the same time as the printed image 42. The printed portions 44 illustrated in fig. 2 are square in shape, but may have any other shape (e.g. circular) in other examples. In some examples, only the left margin 36 or only the right margin 38 may have printed portions 44. The first sensor 261 and the second sensor 262 are arranged to obtain images of at least the left hand margin 36 and the right hand margin 38 respectively. The first sensor 261 and the second sensor 262 are positioned to overlay the left and right hand margins 36, 38 respectively as the substrate 24 moves in direction 40 and underneath the first and second sensors 261 , 262. In other examples, the first and second sensors 261 , 262 may not be positioned to overlay the left and right hand margins 36, 38 (e.g. they may be positioned outside of the margins 36, 38), but may be oriented to obtain images of the left and right hand margins 36, 38. In some examples, the printer apparatus 10 may include only the first sensor 261 or the second sensor 262.

Fig. 2 also illustrates a Cartesian co-ordinate system 46 that includes an x axis 48 and a y axis 50 that are orthogonal to one another. The direction of movement 40 of the substrate 24 is parallel to the y axis 50 and perpendicular to the x axis 48.

The operation of the printer apparatus 10 is described in the following paragraphs with reference to fig. 3.

At block 52, the controller 12 controls printing on at least one portion 44 of the substrate 24 at a predetermined position while printing a print job 42 on the substrate 24. For example, the controller 12 may control the printing fluid rollers 18, the photo imaging roller 16, the blanket roller 20 and the impression drum 22 to print at least one portion 44 in at least one of the margins 36, 38 of the substrate 24. As mentioned above, the printed portions 44 are printed in the left and right hand margins 36, 38 at the same time as the image 42 is printed on the substrate 24 (i.e. the portions 44 and the image 42 are printed concurrently). At block 54, the controller 12 receives image data from the first sensor 261 and/or the second sensor 262 which includes an image of at least one printed portion 44 of the substrate 24. At block 56, the controller 12 determines the position of the at least one printed portion 44 of the substrate 24 from the image data received in block 54. For example, the controller 12 may determine the position of a printed portion 44 by measuring the distance of the printed portion 44 from the edges of the substrate.

At block 58, the controller 12 generates calibration data by comparing the determined position of the printed portion 44 (i.e. the position determined in block 56) with the predetermined position of the portion 44. For example (with reference to fig. 2), the predetermined position (i.e. where the controller 12 intends to print) is labelled with reference numeral 60 and the determined position of the printed portion (i.e. the actual location of printing) is labelled with reference numeral 441 . The position of the printed portion 441 is offset from the predetermined position 60 in the x axis 48 by an amount Δχ, and is offset from the predetermined position in the y axis 50 by an amount Ay. The controller 12 compares the position of the printed portion 441 with the predetermined position 60 and determines that they are offset from one another by the amounts Δχ and Ay. The controller 12 uses these offset amounts to generate calibration data for the printer apparatus 10. The generated calibration data is stored in the memory 30.

The printed portion 441 may include one colour (such as magenta) and the remaining colours may be printed at the predetermined position 60. In this example, the controller 12 may use the calibration data to control the printer apparatus 10 so that the deposition of magenta is correctly aligned with the remaining colours. The controller 12 may generate calibration data from only one of the offsets Δχ and Ay. For example, the controller 12 may generate calibration data for only the Ay offset and then store the calibration data in the memory 30 in order to enable the controller 12 to correct the vertical colour plain registration (VCPR).

In some examples, the method proceeds to block 62, and the controller 12 updates stored calibration data 33 using the calibration data generated in block 58. The controller 12 may update stored calibration data 33 that was previously generated using the method illustrated in fig. 3. For example, the controller 12 may generate and store calibration data by analysing the position of the printed portion 441 , and may update this calibration data by analysing the position of the printed portion 442 in accordance with the method illustrated in fig. 3.

In some examples, the controller 12 may update calibration data 33 that was generated and stored from the calibration software described above (i.e. the colour plain registration (CPR) wizard) that uses data from the static in line scanner (ILS) of the printer apparatus 10. In these examples, the calibration data 33 may be updated as follows:

At block 64, the controller 12 controls the printer apparatus 10 to print the remainder of the print job 42 using the calibration data generated and stored in block 58, or using the stored calibration data updated in block 62. Where the remainder of the print job (and subsequent print jobs) are printed using the updated calibration data from block 62, the continuous calibration of the printer apparatus 10 optimally fixes the entire format by convolution of the data from the substrate's edges (i.e. from the sensors 26) with the 2D calibration data that was obtained during the running of the calibration wizard with the in line scanner (ILS).

The method then returns to block 52 and is repeated. In some examples, the method automatically returns to block 52 after block 64 has been commenced. In other examples, the method returns to block 52 after a predetermined period of time has elapsed since the commencement of block 64. In further examples, the method returns to block 52 in response to a user request.

The printer apparatus 10 provides an advantage in that since calibration data is generated while a print job is being performed (due to the printed portions 44 being printed alongside the print job), the controller 12 may use the generated calibration data to calibrate the printing of the remainder of the same print job and subsequent print jobs. This is advantageous because printing accuracy (which may be referred to as miss registration) may change over time due to ageing components of the printer apparatus 10 and due to process variables that change over time. The printer apparatus 10 may advantageously not require the calibration wizard to be run more than once since the calibration data generated by the colour plain registration wizard may be corrected using the method illustrated in fig. 3. The printer apparatus 10 also provides an advantage in that since calibration data may be generated while a print job is being performed, it may not be necessary to interrupt a print job to run the calibration wizard or even run the calibration wizard in between print jobs. Consequently, the printer apparatus 10 may be used relatively continuously and this may increase the rate of output of the printer apparatus 10. The blocks illustrated in the Figs. 3 may represent steps in a method and/or sections of code in the computer program 32. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some blocks to be omitted.

Although examples of the present invention have been described in the preceding paragraphs, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed.

Features described in the preceding description may be used in combinations other than the combinations explicitly described. Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not.

Although features have been described with reference to certain examples, those features may also be present in other examples whether described or not.

Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

I/we claim:

Claims

1 . A method of calibrating printer apparatus, the method comprising:

controlling printing on at least one portion of a substrate at a predetermined position while printing a print job on the substrate;

receiving image data including the at least one printed portion of the substrate;

determining the position of the at least one printed portion of the substrate from the image data; and

generating calibration data by comparing the determined position of the at least one portion with the predetermined position of the at least one portion.

2. A method as claimed in claim 1 , wherein the predetermined position is located around a perimeter of the print job on the substrate and adjacent an edge of the substrate.

3. A method as claimed in claim 1 , further comprising updating stored calibration data using the generated calibration data.

4. A method as claimed in claim 1 , further comprising controlling printing of the print job using the calibration data.

5. A method as claimed in claim 1 , wherein comparing the determined position of the at least one portion with the predetermined position includes determining whether the at least one portion is offset from the predetermined position in a first dimension and/or a second different dimension.

6. Printer apparatus comprising:

a controller to:

control printing on at least one portion of a substrate at a predetermined position while printing a print job on the substrate; receive image data including the at least one printed portion of the substrate;

determine the position of the at least one printed portion of the substrate from the image data; and

generate calibration data by comparing the determined position of the at least one portion with the predetermined position of the at least one portion.

7. Printer apparatus as claimed in claim 6, wherein the predetermined position is located around a perimeter of the print job on the substrate and adjacent an edge of the substrate.

8. Printer apparatus as claimed in claim 6, wherein the controller is arranged to update stored calibration data using the generated calibration data.

9. Printer apparatus as claimed in claim 6, wherein the controller is arranged to control printing of the print job using the calibration data.

10. Printer apparatus as claimed in claim 6, wherein the controller is arranged to determine whether the at least one portion is offset from the predetermined position in a first dimension and/or a second different dimension when comparing the determined position of the at least one portion with the predetermined position.

1 1 . A non-transitory computer-readable storage medium encoded with instructions that, when performed by a processor, cause performance of: controlling printing on at least one portion of a substrate at a predetermined position while printing a print job on the substrate;

determining the position of the at least one printed portion of the substrate from the image data; and generating calibration data by comparing the determined position of the at least one portion with the predetermined position of the at least one portion.

12. A non-transitory computer-readable storage medium as claimed in claim 1 1 , wherein the predetermined position is located around a perimeter of the print job on the substrate and adjacent an edge of the substrate.

13. A non-transitory computer-readable storage medium as claimed in claim 1 1 encoded with instructions that, when performed by a processor, cause performance of updating stored calibration data using the generated calibration data.

14. A non-transitory computer-readable storage medium encoded with instructions that, when performed by a processor, cause performance of controlling printing of the print job using the calibration data.

15. A non-transitory computer readable storage medium as claimed in claim 1 1 , wherein comparing the determined position of the at least one portion with the predetermined position includes determining whether the at least one portion is offset from the predetermined position in a first dimension and/or a second different dimension.