GB2377909A

GB2377909A - Printer with a ribbon feed path including a pivotably movable ribbon feed arm disposed between a storage spool and a take-up spool

Info

Publication number: GB2377909A
Application number: GB0117880A
Authority: GB
Inventors: David Troman
Original assignee: Markem Technologies Ltd
Current assignee: Markem Imaje Industries Ltd
Priority date: 2001-07-21
Filing date: 2001-07-21
Publication date: 2003-01-29
Also published as: GB0117880D0

Abstract

A printing apparatus 10 includes a storage spool 16 for a carrier (e.g. a ribbon 14) of marking medium, and a take-up spool 18. A ribbon feed path from the storage spool, passes through a printing station 11, to the take-up spool. The feed path includes ribbon guide rollers 20a-d. An elongate ribbon feed arm 25, which is provided to move the ribbon through the printing station during printing, includes ribbon entrainment rollers 26a,26b. In use, the ribbon feed arm is pivotably movable during printing about an axis A in the direction of arrow B to cause ribbon movement along the carrier feed path (shown by directional arrow C) and through the printing station. The storage and take-up spools may be rotatable about a common axis A of rotation and a inclined ribbon guide (20,Fig.2) may be provided to guide the ribbon from a first axial location on the storage spool to a second axial location on the take-up spool.

Description

Title: Improvements in or Relating to Printing Apparatus Description of Invention This invention relates to a printing apparatus and more particularly to a printing apparatus of the kind in which marking medium such as ink is carried on a carrier such as a ribbon or foil, passes through a printing station where there is a print head, the print head having printing elements, such as for example only, thermal printing elements, which are actuated to remove marking medium from the carrier and to deposit pixels of the marking medium on an adjacent substrate at or moving through the printing station, to achieve printing.

Such apparatus are used in environments such as packaging lines and are used for printing information on packages.

Particularly but not exclusively with so called thermal printing apparatus in which the print head has thermal printing elements which when actuated produce heat to soften and remove pixels of marking medium from the carrier, it is essential continuously to present adjacent the print head fresh carrier during printing so that pixels of marking medium may continue to be removed from the carrier. Hence conventionally, where a substrate moves past the print head 12 during printing, the carrier is accelerated up to or close to the speed at which the substrate is moving past the printing station, although in order not to waste carrier, in-between printing, e. g. whilst awaiting arrival of a next substrate at the printing station, conventionally carrier movement is stopped.

The carrier is carried on a storage spool from which the carrier is unwound for use. The carrier tends to be thin and is liable to breakage as a result of being pulled off the storage spool and accelerated up to the speed of the substrate.

Proposals have been put forward to overcome or reduce this problem, for example in our own previous patent application number GB-A-2306916 in which there is proposed the use of a shuttle which entrains carrier, the shuttle moving linearly during printing to move carrier along a carrier feed path past a print head without having to remove carrier simultaneously from a storage spool. Rather, in-between printing operations, a take-up spool is moved to takeup used carrier and to withdraw fresh carrier from the storage spool which is used for a subsequent printing operation.

Whereas our previous proposal operates well, the proposal is restrictive in terms of the length of image which can be printed which is limited to the length of carrier which can be moved past the print head during printing by the shuttle movement, and the shuttle movement which can be achieved is restricted by the space available for such shuttle movement.

Accordingly it is an object of the present invention to provide a new or improved printing apparatus.

According to a first aspect of the invention we provide a printing apparatus having a printing station through which carrier is moved during printing relative to a print head while pixels of marking medium are selectively removed from the carrier by printing elements of the print head, there being carrier feed means to move the carrier through the printing station during printing, the carrier being stored on a carrier storage spool and subsequent to use being taken-up onto a carrier take-up spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station characterised in that the carrier feed means includes a carrier feed member which has carrier entrainment means about which the carrier is entrained, the member being moveable during printing about an axis to cause carrier movement along the carrier feed path and through the printing station.

The apparatus of the invention provides advantages over our prior proposal, in that it is not necessary linearly to move a shuttle, but rather the carrier feed member can be moved, e. g. rotated about the axis to achieve movement of the carrier past the print head.

The length of image which can be printed is not restricted by amount of space available for linear shuttle movement. Rather, for example, the carrier feed member may extend either side of the axis and have carrier entrainment means at opposite sides of the axis. Thus the distance between the carrier entrainment means at opposite sides of the axis, and the extent of rotational movement of the carrier feed member will govern the amount of carrier available for movement past the print head, and thus the length of image which can be printed using that available carrier.

The carrier feed member may be rotatable in a first direction of rotation about the axis to move the carrier through the printing station relative to the print head during printing and rotatable in a second direction of rotation about the axis subsequent to printing while the storage and take-up spools may be rotated to pay out carrier from the storage spool and to take up carrier which has subsequently been used during printing, onto the take-up spool.

To facilitate carrier movement relative to the carrier feed member entrainment means in-between printing operations, the carrier entrainment means may include roller or other bearing means. However during printing to permit the carrier feed member movement to move the carrier past the print head, if required, means may be provided to restrain the storage and take-up spools from moving during printing.

In one example the storage and take-up spools are each rotatable about a common axis of rotation, there being carrier guide means to guide the carrier from a first axial location on the storage spool to a second axial location on the take-up spool. Thus the printing apparatus may be made spatially more compact in a direction radially of the common axis than a conventional printing

apparatus arrangement in which the storage and take-up spools are rotatable about parallel spaced axes.

Preferably the common axis is coincident with the axis about which the carrier feed member moves during printing.

In order to permit the carrier to be stored on the storage spool at one axial location and taken up onto the take-up spool at another axial location, the carrier guide means may include a first edge and a second edge, the edges being relatively inclined, the carrier passing over the edges. Both of the relatively inclined edges are preferably inclined relative to the axis of rotation of the storage and carrier spools.

The edges could be provided by rollers, although preferably the edges include a plurality of generally radially extending openings through which in use, air is passed to provide an air bearing to facilitate movement of the carrier over the edge.

According to a second aspect of the invention we provide a printing apparatus having a printing station including a print head, pixels of marking medium being selectively removed from the carrier by printing elements of the print head during printing for deposit on a substrate, the carrier being stored on a carrier storage spool and subsequent to use being taken-up onto a carrier takeup spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station characterised in that the storage spool and the take-up spool are each rotatable about a common axis of rotation, there being carrier guide means to guide the carrier from a first axial location on the storage spool to a second axial location on the take-up spool.

The printing apparatus of the second aspect of the invention may have any of the features of the apparatus of the first aspect of the invention.

According to a third aspect of the invention we provide a method of printing using a printing apparatus having a printing station through which

carrier is moved during printing relative to a print head while pixels of marking medium are selectively removed from the carrier by printing elements of the print head, there being carrier feed means to move the carrier through the printing station during printing, the carrier being stored on a carrier storage spool and subsequent to use being taken-up onto a carrier take-up spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station and wherein the carrier feed means includes a carrier feed member which has carrier entrainment means about which the carrier is entrained, the method including moving the carrier feed member during printing about an axis to cause carrier movement along the carrier feed path and through the printing station.

The axis about which the carrier feed member is moveable during printing may be coincident with an axis of rotation about which the carrier storage spool and/or the carrier take-up spool rotates.

According to a fourth aspect of the invention we provide a method of moving carrier in a printing apparatus which includes a printing station which includes a print head which has a plurality of printing elements which are selectively actuable to remove pixels of marking medium from the carrier for deposition on a substrate during printing, the carrier being stored on a carrier storage spool and subsequent to use being taken-up onto a carrier take-up spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station characterised in that the method includes rotating the carrier storage spool and the carrier take-up spool about a common axis of rotation, and guiding the carrier from a first axial location on the storage spool to a second axial location on the take-up spool.

The invention will now be described with reference to the accompanying drawings in which-

FIGURE 1 is an illustrative side view of a printing apparatus in accordance with the invention ; FIGURE 2 is an illustrative view of a carrier guide means which may be used with the apparatus of figure 1.

Referring to the drawings, there is shown a printing apparatus 10 which includes a printing station 11 at which a print head 12 is provided. In this example, the print head is at a fixed position, and in use substrates, such as for example, packaged items, are conveyed past the printing station 11 where an image is printed on each item, by the print head 12. In another example though, some print head 12 movement at the printing station 11, in a direction along the item may be provided for, for example as described in our previous patent application GB-A-2302523.

The apparatus 10 shown is intended for positioning at the end of a packaging line for example, and the images to be printed may be batch numbers, sell-by dates or the like. However any other desired image may be printed upon the items as required.

In this example, the print head 12 is of the thermal kind, having a plurality of thermal printing elements, usually arranged in a linear array 13, the individual printing elements being selectively addressable by computer controlled means to cause individual printing elements to become heated and thus to soften pixels of marking medium on adjacent carrier 14 positioned between the print head 12 and the substrate, to be removed from the carrier 14 and deposited on the adjacent moving substrate.

The carrier 14 is intended for single use, that is, the carrier 14 has to be simultaneously moved with the substrate past the print head 12 while the printing elements are energised, so that fresh carrier 14 is continuously presented adjacent the print head 12 so that marking medium is available for printing.

Preferably, the carrier 14 and substrate move at the same speed past the print head 12, but in another example, the carrier 14 and substrate may differentially be moved for carrier saving purposes or for the purpose of achieving print quality advantages.

In-between printing operations it is desired not to continue to move carrier 14 from the storage spool though the printing station 11 such as to waste carrier. Accordingly, conventionally the carrier 14 is only moved during printing, although to ensure that the carrier 14 is accelerated up to the speed of a substrate approaching the printing station 11, carrier 14 movement is usually commenced just prior to arrival of a substrate adjacent the print head 12, and the carrier 14 is decelerated and thus continues to move for a short while after printing.

In the present example, carrier 14 is stored on a storage spool 16 and is fed from the storage spool 16 along a carrier feed path 17, through the printing station 11 and then on to a take-up spool 18. It will be appreciated that particularly when the storage spool 16 is full, considerable stress would be exerted on the, usually thin, carrier 14, during initial acceleration of the carrier 14 up to substrate speed, and that this can result in carrier 14 breakage.

In accordance with the invention, during printing using the printing apparatus 10 shown in figure 1, carrier 14 breakage is minimised or avoided altogether, because during the initial acceleration of the carrier 14 immediately prior to printing, and during printing, carrier 14 is moved past the print head 12 without carrier 14 having to be paid-out from the storage spool 16.

This is achieved because the ribbon feed path 17 includes ribbon guide means 20a, 20b, 20,20c, being in this example rollers, posts or other low friction guide means, around which the carrier 14 is guided, and there is provided a carrier feed member 25 which has carrier entrainment means 26a, 26b around which the carrier 14 is entrained.

The carrier feed member 25 is in this example an elongate arm-like member 25 which is pivoted for rotation about an axis A, and the respective carrier entrainment means 26a, 26b are positioned towards opposite ends of the arm member 25, at either side of the pivot axis A.

The apparatus 10 is operated at follows.

Starting with the arm member 25 in the position shown and with the spools 16,18 stationary, it will be appreciated that the carrier feed path 17 will include a length of carrier 14 entrained about the carrier entrainment means 26a, 26b of the arm member 26 and the guide means 20a, 20b, 20c, 20d of the printing station 11.

As a substrate approaches and it is desired to accelerate the carrier 14 up towards the speed of the substrate, the arm member 25 is rotated about the pivot axis A in the rotational direction shown by arrow B. The spools 16,18 will continue to be stationary, and indeed if required means such as a brake or clutch may be used to maintain the spools 16,18, or at least the storage spool 16 stationary, while the arm member 25 rotates about the pivot axis A in direction B.

Consequently, carrier 14 will be moved past the print head 12 in the direction indicated by arrow C and the carrier 14 will continue thus to be moved until the arm member 25 is pivoted to the position shown in dotted lines. During the arm member 25 movement, as the substrate moves past the print head 12 with carrier 14, the printing elements of the print head 12 are actuated to effect printing of an image on the substrate.

At the end of printing, e. g. as the substrate moves away from the printing station 11, the arm member 25 is pivoted in an opposite direction of rotation to arrow B while the storage spool 16 is rotated in the rotational direction B to pay out fresh carrier 14, and the take-up spool 18 is rotated also in the direction B to take up used carrier 14 from the carrier feed path 17.

The print head 12 may be of the kind which is moveable towards the carrier 14 and substrate to effect printing, and after printing is moveable away from the carrier 14, and substrate if still present at the printing station 11.

It will be appreciated from figure 1 that the storage spool 16 is rotatable about a common axis with the take-up spool 18, and in this example, this common axis is coincident with the pivot axis A of the arm member 25.

Thus the carrier 14, when on the storage spool 16, is at a first axial position along axis A, and when on the take-up spool 18 is at an alternative axial position along axis A.

The ribbon feed path 17 may be co-planar with the storage spool 16 as shown. In this event, after printing, to achieve smooth transfer of carrier onto the take-up spool 18, a guide means such as shown at 20 in figure 2 may be provided.

The guide means 20 of figure 2 includes a pair of external surfaces 30, 31 which are joined but relatively inclined, preferably at about right angles.

Each surface 30,31 is preferably made of a smooth material, such as a smooth plastic, at one end of each surface 30, 31, there is provided a respective edge 32,33. Thus the edges 32,33 are relatively inclined too.

The carrier 14 is fed from the carrier feed path 17 along a first one of the surfaces 30, around the edge 30 thereof, and then around the edge 33 of the other, second, surface 31, and finally along the second surface 31 in an opposite direction to the direction of movement of the carrier 14 along the first surface 30, and hence on to the take-up spool 18. Thus the carrier 14 is guided from the one axial position of spool 16 and the carrier feed path 17, on to the take-up spool 18 in another axial position.

Of course if desired, the guide means 20 of figure 2 or an alternative appropriate guide means, may be provided to guide the carrier 14 from the storage spool 16 in one axial location, to the carrier feed path 17 in a spaced axial location common to or spaced from the axial location of the take-up spool

18. Where both the storage 16 and take-up spool 18 are spaced axially relative to each other and to the carrier feed path 17 through the printing station 11, a pair or more of guide means such as indicated at 20 in figure may be provided.

Referring again to figure 2 it can be seen that each edge 32,33 of the guide means 20 is of tubular configuration, both to provide a smooth bearing surface for the carrier 14, but also so that air may be passed into hollows 35 of the tubular edge formations 32,33, and pass out of the tubular formations 35 through a plurality of small generally radially extending openings 36. This passage of air out of the tubular formations 35 aids movement of the carrier 14 over the edges 32,33 in the manner of an air bearing.

Alternative guide means arrangements to that shown in figure 2 are no doubt possible.

If desired, after a printing operation, the carrier 14 may be moved back past the print head 12 for repeat use. This is achieved in the example of figure 1, by moving the arm member 25 from the dotted line position to the full line position without rotating the spools 16,18 or by rotating the spools only to move a small length of the carrier onto the take-up spool 18. Thus carrier saving may be achieved, for example in the manner described in our prior patent application GB-A-2289441 for a so-called single strike carrier 14, or a so-called multi-strike carrier 14 may be used.

After repeat use, which may be one or more repeat uses of the carrier 14, the carrier 14 may be wound on to present fresh carrier at the printing station 12, in the manner described above.

Further modifications may be made without departing from the scope of the invention.

For example, the arm member 25 need not be of elongate configuration, and the distance between the entrainment means 26a, 26b may be made as great as space permits, to achieve different lengths of carrier 14 along the carrier feed path 17 and thus available for printing an image of a desired length. For

example for a small length image, the distance between the entrainment means 26a, 26b may be relatively small, whilst for a particular long image, the distance between entrainment means 26a, 26b may be greater that that shown in figure 1.

It will be appreciated that although it is preferred for the storage 16 and take-up spools 18 to be rotatable about a common axis, the common axis need not be coincident with the pivot axis of the carrier feed member 25, or indeed in accordance with the first aspect of the invention, the spools 16,18 need not be rotatable about a common axis at all.

According to the second aspect of the invention, movement of carrier past the print head 12 in a printing apparatus of the kind illustrated, may be achieved by means other than the carrier feed member 25, for example by a conventional capstan drive or direct spool drive arrangement. The invention of the second aspect is applicable to other kinds of printing apparatus where carrier is paid out and taken up on spools.

The invention is applicable to other than thermal printers which utilise a ribbon or foil carrier for carrying marking medium such as ink, in which case an alternative kind of print head 12 to that described may be provided. For example the invention may be applied to other pixel based printing systems, such as dot matrix type printers.

The features disclosed in the foregoing description, or the following claims, or the accompanying drawings, expressed in their specific forms or in terms of a means for performing the disclosed function, or a method or process for attaining the disclosed result, as appropriate, may, separately, or in any combination of such features, be utilised for realising the invention in diverse forms thereof.

Claims

CLAIMS 1. A printing apparatus having a printing station through which carrier is moved during printing relative to a print head while pixels of marking medium are selectively removed from the carrier by printing elements of the print head, there being carrier feed means to move the carrier through the printing station during printing, the carrier being stored on a carrier storage spool and subsequent to use being taken-up on a carrier take-up spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station characterised in that the carrier feed means includes a carrier feed member which has carrier entrainment means about which the carrier is entrained, the member being moveable during printing about an axis to cause carrier movement along the carrier feed path and through the printing station.
2. An apparatus according to claim 1 characterised in that the carrier feed member extends either side of the axis and has carrier entrainment means at opposite sides of the axis.
3. An apparatus according to claim 1 or claim 2 characterised in that the carrier feed member is rotatable in a first direction of rotation about the axis to move the carrier through the printing station relative to the print head.
4. An apparatus according to claim 3 characterised in that the carrier feed member is rotatable in a second direction of rotation about the axis subsequent to printing while the storage and take-up spools are rotated to remove carrier from the storage spool and to take up carrier which has subsequently been used during printing, onto the take-up spool.

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5. An apparatus according to any one of the preceding claims characterised in that the carrier entrainment means include roller means.
6. An apparatus according to any one of the preceding claims characterised in that means are provided to restrain the storage and take-up spools from moving during printing.
7. An apparatus according to any one of the preceding claims characterised in that the storage and take-up spools are each rotatable about a common axis of rotation, there being carrier guide means to guide the carrier from a first axial location on the storage spool to a second axial location on the take-up spool.
8. An apparatus according to claim 7 characterised in that common axis is coincident with the axis about which the carrier feed member moves during printing.
9. An apparatus according to claim 7 or claim 8 characterised in that the carrier guide means includes a first edge and a second edge, the edges being relatively inclined, the carrier passing over the edges.
10. An apparatus according to claim 9 characterised in that both of the relatively inclined edges are inclined relative to the axis of rotation of the storage and carrier spools.
11. An apparatus according to claim 10 characterised in that at least one of the edges includes a plurality of generally radially extending openings through which in use, air is passed to provide an air bearing to facilitate movement of the carrier over the edge.

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12. A printing apparatus having a printing station through which carrier is moved during printing relative to a print head while pixels of marking medium are selectively removed from the carrier by printing elements of the print head, there being carrier feed means to move the carrier through the printing station during printing, the carrier being stored on a carrier storage spool and subsequent to use being taken-up on a carrier take-up spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station characterised in that the storage spool and the take-up spool are each rotatable about a common axis of rotation, there being carrier guide means to guide the carrier from a first axial location on the storage spool to a second axial location on the take-up spool.
13. A printing apparatus according to claim 12 characterised in that the apparatus has any of the features of the apparatus of any one of claims 1 to 11.
14. A printing apparatus substantially as hereinbefore described with reference to and as shown in the accompanying drawings.
15. A method of printing using a printing apparatus having a printing station through which carrier is moved during printing relative to a print head while pixels of marking medium are selectively removed from the carrier by printing elements of the print head, there being carrier feed means to move the carrier through the printing station during printing, the carrier being stored on a carrier storage spool and subsequent to use being taken-up on a carrier take-up spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station and wherein the carrier feed means includes a carrier feed

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member which has carrier entrainment means about which the carrier is entrained, the method including moving the carrier feed member during printing about an axis to cause carrier movement along the carrier feed path and through the printing station.
16. A method according to claim 15 characterised in that the axis about which the carrier feed member is moveable during printing is coincident with an axis of rotation about which the carrier storage spool and/or the carrier takeup spool rotates.
17. A method of printing using a printing apparatus which includes a printing station through which carrier is moved during printing relative to a print head while pixels of marking medium are selectively removed from the carrier by printing elements of the print head, there being carrier feed means to move the carrier through the printing station during printing, the carrier being stored on a carrier storage spool and subsequent to use being taken-up on a carrier take-up spool, the carrier extending along a carrier feed path which includes carrier guide means, from the storage spool to the carrier take-up spool and through the printing station characterised in that the method includes rotating the carrier storage spool and the carrier take-up spool about a common axis of rotation, and guiding the carrier from a first axial location on the storage spool to a second axial location on the take-up spool.
18. Any novel feature or novel combination of features described herein and/or shown in the accompanying drawings.