NL2028316B1 - Method of Slant Error Correction in a Printer - Google Patents

Method of Slant Error Correction in a Printer Download PDF

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Publication number
NL2028316B1
NL2028316B1 NL2028316A NL2028316A NL2028316B1 NL 2028316 B1 NL2028316 B1 NL 2028316B1 NL 2028316 A NL2028316 A NL 2028316A NL 2028316 A NL2028316 A NL 2028316A NL 2028316 B1 NL2028316 B1 NL 2028316B1
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NL
Netherlands
Prior art keywords
web
angle
machine frame
inclination
transport mechanism
Prior art date
Application number
NL2028316A
Other languages
Dutch (nl)
Inventor
Rietbergen Mark
M C Peeters Guus
Original Assignee
Canon Production Printing Holding Bv
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Filing date
Publication date
Application filed by Canon Production Printing Holding Bv filed Critical Canon Production Printing Holding Bv
Priority to NL2028316A priority Critical patent/NL2028316B1/en
Priority to DE102022112307.3A priority patent/DE102022112307A1/en
Application granted granted Critical
Publication of NL2028316B1 publication Critical patent/NL2028316B1/en

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J2/00—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed
    • B41J2/005—Typewriters or selective printing mechanisms characterised by the printing or marking process for which they are designed characterised by bringing liquid or particles selectively into contact with a printing material
    • B41J2/01—Ink jet
    • B41J2/21—Ink jet for multi-colour printing
    • B41J2/2132—Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding
    • B41J2/2146—Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding for line print heads
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J11/00—Devices or arrangements  of selective printing mechanisms, e.g. ink-jet printers or thermal printers, for supporting or handling copy material in sheet or web form
    • B41J11/0095—Detecting means for copy material, e.g. for detecting or sensing presence of copy material or its leading or trailing end
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J13/00—Devices or arrangements of selective printing mechanisms, e.g. ink-jet printers or thermal printers, specially adapted for supporting or handling copy material in short lengths, e.g. sheets
    • B41J13/08—Conveyor bands or like feeding devices
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
    • B41J—TYPEWRITERS; SELECTIVE PRINTING MECHANISMS, i.e. MECHANISMS PRINTING OTHERWISE THAN FROM A FORME; CORRECTION OF TYPOGRAPHICAL ERRORS
    • B41J25/00—Actions or mechanisms not otherwise provided for
    • B41J25/001—Mechanisms for bodily moving print heads or carriages parallel to the paper surface
    • B41J25/003—Mechanisms for bodily moving print heads or carriages parallel to the paper surface for changing the angle between a print element array axis and the printing line, e.g. for dot density changes
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H5/00—Feeding articles separated from piles; Feeding articles to machines
    • B65H5/02—Feeding articles separated from piles; Feeding articles to machines by belts or chains, e.g. between belts or chains
    • B65H5/021—Feeding articles separated from piles; Feeding articles to machines by belts or chains, e.g. between belts or chains by belts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H5/00—Feeding articles separated from piles; Feeding articles to machines
    • B65H5/22—Feeding articles separated from piles; Feeding articles to machines by air-blast or suction device
    • B65H5/222—Feeding articles separated from piles; Feeding articles to machines by air-blast or suction device by suction devices
    • B65H5/224—Feeding articles separated from piles; Feeding articles to machines by air-blast or suction device by suction devices by suction belts
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
    • B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
    • B65H7/06—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors responsive to presence of faulty articles or incorrect separation or feed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H7/00—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles
    • B65H7/02—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors
    • B65H7/14—Controlling article feeding, separating, pile-advancing, or associated apparatus, to take account of incorrect feeding, absence of articles, or presence of faulty articles by feelers or detectors by photoelectric feelers or detectors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H9/00—Registering, e.g. orientating, articles; Devices therefor
    • B65H9/002—Registering, e.g. orientating, articles; Devices therefor changing orientation of sheet by only controlling movement of the forwarding means, i.e. without the use of stop or register wall
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H9/00—Registering, e.g. orientating, articles; Devices therefor
    • B65H9/16—Inclined tape, roller, or like article-forwarding side registers
    • B65H9/163—Tape
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2404/00—Parts for transporting or guiding the handled material
    • B65H2404/20—Belts
    • B65H2404/25—Driving or guiding arrangements
    • B65H2404/253—Relative position of driving and idler rollers
    • B65H2404/2532—Arrangement for selectively changing the relative position of the driving and idler rollers
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2404/00—Parts for transporting or guiding the handled material
    • B65H2404/20—Belts
    • B65H2404/26—Particular arrangement of belt, or belts
    • B65H2404/269—Particular arrangement of belt, or belts other arrangements
    • B65H2404/2693—Arrangement of belts on movable frame
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2511/00—Dimensions; Position; Numbers; Identification; Occurrences
    • B65H2511/20—Location in space
    • B65H2511/21—Angle
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2511/00—Dimensions; Position; Numbers; Identification; Occurrences
    • B65H2511/20—Location in space
    • B65H2511/21—Angle
    • B65H2511/214—Inclination
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2511/00—Dimensions; Position; Numbers; Identification; Occurrences
    • B65H2511/20—Location in space
    • B65H2511/24—Irregularities, e.g. in orientation or skewness
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2553/00—Sensing or detecting means
    • B65H2553/40—Sensing or detecting means using optical, e.g. photographic, elements
    • B65H2553/41—Photoelectric detectors
    • B65H2553/416—Array arrangement, i.e. row of emitters or detectors
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2553/00—Sensing or detecting means
    • B65H2553/40—Sensing or detecting means using optical, e.g. photographic, elements
    • B65H2553/42—Cameras
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B65—CONVEYING; PACKING; STORING; HANDLING THIN OR FILAMENTARY MATERIAL
    • B65H—HANDLING THIN OR FILAMENTARY MATERIAL, e.g. SHEETS, WEBS, CABLES
    • B65H2801/00—Application field
    • B65H2801/03—Image reproduction devices
    • B65H2801/21—Industrial-size printers, e.g. rotary printing press

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Quality & Reliability (AREA)
  • Ink Jet (AREA)

Abstract

A method of slant error correction in a printer (10) which comprises: - a machine frame (12); - a web transport mechanism (14) arranged for moving a web (16), relative to the machine frame (12), in a transport direction (A); - a stationary print array (18) mounted on the machine frame (12) so as to face the moving web (16); and - an adjusting mechanism (20) for adjusting the web transport mechanism (14) relative to the machine frame (12), the method being characterized by the steps of: - detecting a slant angle (8) of the print array (18) relative to the transport direction (A); and - using the adjusting mechanism (20) for rotating the web transport mechanism (14) and thereby eliminating the slant angle.

Description

Method of Slant Error Correction in a Printer The invention relates to a method of slant error correction in a printer which comprises: - a machine frame;
- a web transport mechanism arranged for moving a web, relative to the machine frame, in a transport direction; - a stationary print array mounted on the machine frame so as to face the moving web; and
- an adjusting mechanism for adjusting the web transport mechanism relative to the machine frame.
US 2016/137447 A1 describes an ink jet printer which has the features set out above and in which the web transport mechanism and the web constitute a belt conveyor for moving media sheets past the print array.
The adjusting mechanism is used for aligning the media sheets that are transported on the conveyor belt (the web) with a stationary print head assembly that constitutes the print array.
The print head assembly has a number of page-wide print heads each of which has at least one row of equally spaced ink jet printing elements (nozzles) which can be activated individually for printing images onto the media sheets.
When a media sheet is moved in the transport direction and passes through underneath the print array, each nozzle prints a pixel line onto the sheet.
In order to achieve a high print resolution, the nozzles of each print head are staggered in several parallel rows that, ideally, are orthogonal to the transport direction.
Manufacturing errors may result in a misalignment of the print array relative to the web transport mechanism, and this misalignment may include a rotation of the print array about an axis that is normal to the plane of the web.
In this case, the direction of the rows of the printing elements or nozzle forms a non-zero slant angle with the normal to the transport direction.
This has the consequence that the nozzles that belong to different rows are shifted by different amounts in the direction orthogonal to the transport direction.
As a result, the pixel lines that are printed with the different nozzle rows are no longer evenly spaced, and the printed image becomes streaky.
It is therefore an object of the invention to provide a method for correcting the slant error of the print array with high precision. In order to achieve this object, the method according to the invention is characterized by the steps of! - detecting a slant angle of the print array relative to the transport direction; and - using the adjusting mechanism for rotating the web transport mechanism and thereby eliminating the slant angle.
Thus, according to the invention, the slant angle is not corrected by rotating the print array such that the rows of printing elements form a right angle with the transport direction that is defined by the web transport mechanism, but instead the web transport mechanism is rotated such that the transport direction becomes orthogonal to the direction defined by the rows of printing elements. This has the advantage that the slant angle can be corrected with higher accuracy because the web transport mechanism has relatively large dimensions, as compared to the print array, so that the angle of rotation of the web transport mechanism and the web can be controlled with high accuracy by means of the adjusting mechanism. Moreover, if the adjusting mechanism for the web transport mechanism is available, anyway, then no additional adjusting means are required for adjusting the print array.
The invention is not limited to printers wherein the web transport mechanism and the web form a belt conveyor, but is also applicable to roll-to-roll-printers, for example, wherein the web is constituted by the print medium itself.
More specific optional features of the invention are indicated in the dependent claims.
If the print array is constituted by a plurality of page-wide print heads, then the method according to the invention can be used for eliminating an overall slant angle of these print heads. Typically, the print heads are mounted on a common print head carrier in a configuration in which the print heads are juxtaposed to one another or at least are arranged with only small spacings in the transport direction. Therefore, the alignment tolerances of the individual print heads relative to one another can generally be kept small, and a major contribution to the total slant error is due to alignment tolerances of the common print head carrier.
Therefore, a substantial improvement is achieved when the invention is used for eliminating the slant error of the print head carrier.
The slant error of an individual print head can be determined with high precision by inspecting a test image that has been printed with this print head.
More specifically, an optical sensor can be used for measuring the imbalance in the spacings between the pixel lines that give rise to the streakiness of the image.
In one embodiment, for a printer that has a plurality of print heads, the slant angles of all print heads are measured individually, and the overall slant angle that is to be corrected by adjusting the web transport mechanism is obtained by identifying the pair of print heads for which the difference of the slant angles is largest and then taking the average of these two slant angles.
In an alternative embodiment, the averaged is determined by determining the average value of the respective slant angles of all print heads.
An embodiment example will now be described in conjunction with the drawings, wherein: Fig. 1 is a schematic top plan view of a printer to which the invention is applicable; Fig. 2 is a view analogous to Fig. 1 and shows a result of a slant angle correction;
Fig. 3 is a diagram illustrating a method for calculating a slant angle; Fig. 4 is a schematic top plan view of a print array constituted by a plurality of print heads; and
Figs. 5 and 6 are not-to-scale views illustrating a method of correcting an overall slant error of the print array shown in Fig. 4. Fig. 1 shows a printer 10 having a machine frame 12, a web transport mechanism 14 arranged for moving a web 16 in a transport direction A, a stationary print array 18 and an adjusting mechanism which, in this example, is formed by two actuators 20 for adjusting the web transport mechanism 14 relative to the machine frame 12. The machine frame 12 has two side members 22 interconnected by a number of cross bars 24. The web transport mechanism 14 and the web 16 constitute a belt conveyor.
The web 16 forming the conveyor belt is trained around two rollers 26 that are rotatably supported in a conveyor frame 28. At its four corners, the conveyor frame 28 has rollers 30 guided along arcuate guide contours of guide plates 32 that form part of the machine frame 12. In this way, the web transport mechanism 14 is supported such that it is rotatable about a virtual axis that is perpendicular to the plane of the web 16 and passes through the center of the conveyor frame 28. The angular position of the web transport mechanism 14 about this axis can be adjusted by extending and retracting the actuators
20.
In the condition shown in Fig. 1, the web 16 supports a media sheet 34 which has just passed underneath the print array 18 that is suspended from a print head carrier 36 that is rigidly mounted to two of the cross bars 24.
In the simplified example shown in Fig. 1, the print head carrier 36 carries only a single print head which constitutes the print array 18. This print head has two parallel rows of ink jet printing elements 38. Ideally, these rows of printing elements 38 should extend in a direction orthogonal to the transport direction A. The printing elements (nozzles) in the two rows are staggered, so that all nozzles together can print an image consisting of equally spaced pixel lines 40. However, as has been shown exaggeratedly in Fig. 1, inevitable manufacturing and mounting tolerances have caused a misalignment of the print head carrier 36 and consequently also of the rows of printing elements 38 with respect to a line W that is perpendicular to the transport direction A. Consequently, the edges of the print head carrier 16 which are parallel to the rows of printing elements 38 form a slant angle & with the line W. This misalignment has caused a differential lateral shift of the printing elements 38 in the two rows, which destroys the balance between the spacings of the pixel lines 40, so that the printed image has become streaky.
Fig. 2 shows the printer 10 in a more realistic condition in which the slant angle ò is significantly smaller (although still exaggerated). By extending one of the actuators 20 and retracting the other one, the conveyor frame 28 and, with it, the entire web transport mechanism 14 and the web 16 have been rotated about the virtual axis by an angle that is equal to the slant angle 6, so that the rows of printing elements are perpendicular to the transport direction A.
As a consequence, the pixel lines 40 are evenly distributed and the printed image does not appear streaky. 5
Two of the cross bars 24 carry optical sensors 44 which detect the lateral position of one edge of the web 16 in two longitudinal positions that are separated by a relatively large distance in the transport direction A.
In the drawing, the sensors 44 have been symbolized only by their rectangular detection areas.
By measuring the position of the web edge in these two detection areas, it is possible to determine and control the angular position of the web transport mechanism 14 relative to the machine frame 12. Fig. 3 is a diagram illustrating how the slant angle 5 produces the streakiness of the printed image and how this streakiness can be used to determine the slant angle ô.
The top part of Fig. 3 shows one end of the print array 18 with three printing elements 38 in a condition in which the print array is correctly aligned relative to the transport direction, so that the three printing elements 38, although they belong to two different rows and are therefore spaced apart in the transport direction, print pixel lines 40 with equal spacings a and b.
Two lines that connect the two printing elements 38 in the left row in
Fig. 3 to the single printing element in the right row form each an angle a with the pixel lines 40 that extend in the transport direction.
If d designates the spacing between the printing elements 38 in two rows, then the spacings a and b of the pixel lines fulfil the following equation:
a=b=d sin(a) In the bottom part of Fig. 3, the print array 18 has been rotated by the slant angle ò.
As a consequence, the spacings a and b are (as long as ò is small) given by the following two different equations:
a =d sin(a+6) b =d sin(a-ô).
Applying the addition theorems for the sinus function, these equations can also be written as: a=d (sin(a) cos(ô) + cos(a) sind) ) b=d (sin(a) cos(d) - cos(a)sin(5) ) Consequently: a-b=2dcos(a) sin(6) and sin(ò) = (a-b) / (2 d cos{w)).
Thus, by using an optical sensor which is capable to measure the spacings a and b in the printed image, it is possible to determine the slant angle 6 and then to rotate the entire web transport mechanism 14 by that angle so as to eliminate the slant angle of the print array 18 relative to the transport direction A.
Fig. 4 schematically shows essential parts of a printer 10’ which differs from the printer 10 in Figs. 1 and 2 in that the print head carrier 36 carries five page-wide print heads 18a-e which are juxtaposed in the transport direction A and, together, form a print array
18.
Fig, 4 further shows the two actuators 20 connected to an electronic controller 46 that receives also detection signals from the sensors 44 for controlling the angle of rotation of the web transport mechanism. The controller 46 can also be connected to an opto-electronic measuring device 48 for measuring the spacings a and b between the pixel lines 40 and thereby determining a slant angle of the print array 18’. Thus, the printer 10° and the measurement device 48, together, form a printing system which is capable of automatically detecting and eliminating the slant error, i.e. the error caused by a non-zero slant angle of the print array 18’ or at least one of the print heads thereof. The print heads 18a-18e can be manufactured as separate modules with relatively low manufacturing tolerances, so that the rows of printing element are aligned with the longitudinal edges of the print heads with high accuracy. Then, by butting the print heads against one another, possibly with the interposition of spaces with accurately controlled thickness, it can also be assured that all the rows of printing elements of all print heads forming the array 18’ are parallel to one another with high accuracy. In contrast, it is a more difficult task to mount the assembly of the print heads 18a-18e on the print head carrier 36 and to mount the print head carrier 36 on the machine frame with such a high accuracy that the rows of printing element are perfectly parallel to the longitudinal direction of the machine frame 12 which defines the nominal transport direction A.
Nevertheless, the print heads 18a-e may not be exactly parallel to one another, as has been shown exaggeratedly in Fig. 5. Then, the following procedure may be employed for adjusting the web transport mechanism 14 to a position in which an optimal print result can be obtained.
First, the slant angles ò are determined individually for each print head 18a-18e. For example, separate test images can be printed with each of the print heads, and these test images may then be analysed with the measuring device 48 so as to determine the slant angle of each print head. The next step is to identify the pair of print heads for which the difference between the slant angles is largest. In the example shown in Fig. 5, this would be the print heads 18a and 18b. The print head 18a is rotated counterclockwise relative to the transport direction A and the machine frame, so that its slant angle 6a is positive, whereas the print head 18b is rotated clockwise, so that its slant angle 6b is negative.
An overall slant angle ôt can then be defined as the average of the two slant angles 6a and òb of this pair.
dt = (6a + 3b) /2.
This average is the angle ôt formed between the line W that is perpendicular to the transport direction A and the angle bisector B of the two print heads 18a and 18b. If the web transport mechanism 14 and the web 16 are rotated by this angle ôt, then the transport direction A will be perpendicular to the angle bisector B, as has been shown in Fig. 8. Thus, in this position, the slant angle ôt, if measured relative to the transport direction A, has been eliminated. Of course, the individual print heads 18a and 18b still have a certain slant angle which cannot be eliminated or reduced further. However, the resulting lateral shift of the print elements of these print heads and, consequently, the streakiness of the printing image has been made a small as possible. The slant angles of the other print heads 18c, 18d and 18e, measured relative to the transport direction A, are even smaller (in absolute value) than those of the print heads 18a and 18b. Thus, the streakiness of the complete printed image printed with all five print heads has been minimized.
Once the value ôt has been calculated, this value can be used for calculating new target positions t1 and t2 for the edge of the web 16 as measured with the sensors 44. Then, in order to correct or minimize the slant error, the actuators 20 are controlled to move the edge of the web to these target positions.
Embodiments
1. A method of slant error correction in a printer (10; 10’) which comprises: - a machine frame (12); - a web transport mechanism (14) arranged for moving a web (16), relative to the machine frame (12), in a transport direction (A); - a stationary print array (18; 18’) mounted on the machine frame (12) so as to face the moving web (18); and - an adjusting mechanism (20) for adjusting the web transport mechanism (14) relative to the machine frame (12), the method being characterized by the steps of: - detecting a slant angle (8) of the print array (18; 18°) relative to the transport direction (A); and - using the adjusting mechanism (20) for rotating the web transport mechanism (14) and thereby eliminating the slant angle.
2. The method according to claim 1, wherein the web transport mechanism (14) and the web (16) constitute a belt conveyor for moving media sheets (34) past the print array (18; 18°).
3. The method according to claim 1 or 2, wherein the step of detecting the slant angle (3) comprises: - measuring spacings (a, b) of adjacent pixel lines (40) in an image that has been printed with the print array (18); and - calculating the slant angle (6) from the measured spacings (a, b). 4, The method according to any of the preceding claims, wherein the print array (18") is constituted by a plurality of page-wide print heads (18a-18e), the method comprising the steps of: - detecting separate slant angles for each of the print heads; and - calculating an averaged overall slant angle (ôt) for the whole print array on the basis of the detected slant angles.
5. The method according to claim 4, wherein the step of calculating the overall slant angle (ôt) comprises the steps of: - identifying a pair of said print heads (18a-18e) for which the difference of the measured slant angles is largest; and - taking the average of these slant angles as the overall slant angle (6t).
6. The method according to any of the preceding claims, wherein the step of rotating the web transport mechanism (14) comprises: - measuring lateral positions of one edge of the web (16) at two locations that are spaced apart from one another in the transport direction (A); - calculating target positions (t1, t2) for said lateral positions of the edge on the basis of the detected slant angle (6; ót); and - controlling the adjusting mechanism (20) to rotate the web transport mechanism until the measured lateral positions of the edge coincide with the target positions.
7. A printing system comprising a printer (10°) which comprises: - a machine frame (12); - a web transport mechanism (14) arranged for moving a web (18), relative to the machine frame (12), in a transport direction (A); - a stationary print array (18) mounted on the machine frame (12) so as to face the moving web (16); and - an adjusting mechanism (20) for adjusting the web transport mechanism (14) relative to the machine frame (12); and - a controller (46) for controlling the adjusting mechanism (20), characterized in that the system further comprises at least one sensor (44) for detecting an angle between an edge of the web (16) and a longitudinal direction of the machine frame (12), the sensor (44) being connected to the controller (46), the system further comprises a measuring device (48) for detecting a slant angle (3) of the print array (18’) relative to the transport direction (A) by analyzing an image that has been printed with the print array (18) and for sending a signal representing the detected slant angle to the controller (46), and the controller (46) is configured to perform the method according to any of the claims 1 to 6.

Claims (7)

CONCLUSIESCONCLUSIONS 1. Werkwijze voor hellingfoutcorrectie in een drukeenheid (10; 10’) die omvat: - een machineraamwerk (12); - een baantransportmechanisme (14) ingericht voor het verplaatsen van een baan (16), ten opzichte van het machineraamwerk (12), in een transportrichting (A); - een stationaire drukrij (18; 18") gemonteerd op het machineraamwerk (12) om naar de verplaatsende baan (16) gericht te zijn; en - een instelmechanisme (20) voor het instellen van het baantranspartmechanisme (14) ten opzichte van het machineraamwerk (12), waarbij de werkwijze gekenmerkt wordt door de stappen van: - het detecteren van een hellingshoek (d) van de drukrij (18; 18’) ten opzichte van de transportrichting (A); en - het gebruiken van het instelmechanisme (20) voor het roteren van het baantransportmechanisme (14) en het daardoor elimineren van de hellingshoek.A method of slope error correction in a printing unit (10; 10') comprising: - a machine frame (12); - a web transport mechanism (14) adapted to move a web (16), relative to the machine frame (12), in a transport direction (A); - a stationary printing row (18; 18") mounted on the machine frame (12) to face the moving web (16); and - an adjustment mechanism (20) for adjusting the web transfer mechanism (14) relative to the machine frame (12), the method being characterized by the steps of: - detecting an angle of inclination (d) of the print queue (18; 18') with respect to the transport direction (A), and - using the adjusting mechanism (20 ) to rotate the web transport mechanism (14) and thereby eliminate the angle of inclination. 2. Werkwijze volgens conclusie 1, waarbij het baantransportmechanisme (14) en de baan (16) bestaan uit een bandtransporteur voor het verplaatsen van mediavellen (34) voorbij de drukrij (18; 18°).The method of claim 1, wherein the web transport mechanism (14) and the web (16) comprise a belt conveyor for moving media sheets (34) past the print queue (18; 18°). 3. Werkwijze volgens conclusie 1 of 2, waarbij de stap van het detecteren van de hellingshoek (d} omvat: - het meten van afstanden (a, b) van aangrenzende pixellijnen (40) in een beeld dat met de drukrij (18) gedrukt werd; en - het berekenen van de hellingshoek (d) uit de gemeten afstanden (a, b).A method according to claim 1 or 2, wherein the step of detecting the tilt angle (d} comprises: - measuring distances (a, b) of adjacent pixel lines (40) in an image printed with the print queue (18). and - calculating the angle of inclination (d) from the measured distances (a, b). 4, Werkwijze volgens een van de voorgaande conclusies, waarbij de drukrij (18") uit een veelheid van paginabrede drukkoppen (18a-18e) bestaat, de werkwijze omvattende de stappen van: - het detecteren van afzonderlijke hellingshoeken voor elk van de drukkoppen; en - het berekenen van een gemiddelde algemene hellingshoek (dt) voor de hele drukrij op basis van de gedetecteerde hellingshoeken.A method according to any one of the preceding claims, wherein the print queue (18") consists of a plurality of page-wide printheads (18a-18e), the method comprising the steps of: - detecting individual tilt angles for each of the printheads; and - calculating an average overall tilt angle (dt) for the entire print queue based on the detected tilt angles. 5. Werkwijze volgens conclusie 4, waarbij de stap van het berekenen van de algemene hellingshoek (dt) de stappen omvat van:The method of claim 4, wherein the step of calculating the general inclination angle (dt) comprises the steps of: - het identificeren van een paar van genoemde drukkoppen (18a-18e) waarvoor het verschil van de gemeten hellingshoeken het grootst is; en - het nemen van het gemiddelde van deze hellingshoeken als de algemene hellingshoek (dt).- identifying a pair of said printheads (18a-18e) for which the difference of the measured inclination angles is the greatest; and - taking the average of these inclination angles as the overall inclination angle (dt). 6. Werkwijze volgens een van de voorgaande conclusies, waarbij de stap van het roteren van het baantransportmechanisme (14) omvat: - het meten van zijdelingse posities van één rand van de baan (16) op twee locaties die in de transportrichting (A) op een afstand van elkaar geplaatst zijn; - het berekenen van doelposities (t1, t2) voor genoemde zijdelingse posities van de rand op basis van de gedetecteerde hellingshoek (d; dt); en - het regelen van het instelmechanisme (20) om het baantransportmechanisme te roteren totdat de gemeten zijdelingse posities van de rand met de doelposities samenvallen.A method according to any one of the preceding claims, wherein the step of rotating the web transport mechanism (14) comprises: - measuring lateral positions of one edge of the web (16) at two locations located in the transport direction (A) on be spaced apart; - calculating target positions (t1, t2) for said lateral positions of the edge based on the detected inclination angle (d; dt); and - controlling the adjustment mechanism (20) to rotate the web transport mechanism until the measured edge lateral positions coincide with the target positions. 7. Druksysteem omvattende een drukeenheid (10) die omvat: - een machineraamwerk (12); - een baantransportmechanisme (14) ingericht voor het verplaatsen van een baan (16), ten opzichte van het machineraamwerk (12}, in een transportrichting (A); - een stationaire drukrij (18') gemonteerd op het machineraamwerk (12) om naar de verplaatsende baan (16) gericht te zijn; en - een instelmechanisme (20) voor het instellen van het baantransport- mechanisme (14) ten opzichte van het machineraamwerk (12); en - een regeleenheid (46) voor het regelen van het instelmechanisme (20), gekenmerkt doordat het systeem verder ten minste één sensor (44) voor het detecteren van een hoek tussen een rand van de baan (16) en een lengterichting van het machineraamwerk (12) omvat, waarbij de sensor (44) met de regeleenheid (46) verbonden is, waarbij het systeem verder een meetinrichting (48) voor het verzenden van een hellingshoek (d) van de drukrij (18) ten opzichte van de transportrichting (A) omvat door het analyseren van een beeld dat met de drukrij (18') gedrukt werd en voor het verzenden van een signaal dat de gedetecteerde hellingshoek tot de regeleenheid (46) vertegenwoordigt, en de regeleenheid (48) geconfigureerd is om de werkwijze volgens één van conclusies 1 tot 6 uit te voeren.A printing system comprising a printing unit (10) comprising: - a machine frame (12); - a web transport mechanism (14) adapted to move a web (16), relative to the machine frame (12}, in a conveying direction (A), - a stationary print queue (18') mounted on the machine frame (12) to the moving web (16), and - an adjustment mechanism (20) for adjusting the web transport mechanism (14) relative to the machine frame (12), and - a control unit (46) for controlling the adjustment mechanism (20), characterized in that the system further comprises at least one sensor (44) for detecting an angle between an edge of the web (16) and a longitudinal direction of the machine frame (12), the sensor (44) having the control unit (46) is connected, the system further comprising a measuring device (48) for transmitting an angle of inclination (d) of the print queue (18) relative to the transport direction (A) by analyzing an image associated with the print queue (18') was printed and for sending a signal representing the detected angle of inclination to the control unit (46), and the control unit (48) is configured to perform the method of any one of claims 1 to 6.
NL2028316A 2021-05-28 2021-05-28 Method of Slant Error Correction in a Printer NL2028316B1 (en)

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Publication number Priority date Publication date Assignee Title
US20130244872A1 (en) * 2009-12-22 2013-09-19 Zih Corp. Direct thermal media and registration sensor system and method for use in a color thermal printer
US20130222459A1 (en) * 2012-02-28 2013-08-29 Dainippon Screen Mfg. Co., Ltd. Data processing method of printing apparatus and the printing apparatus
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