GB2314808A

GB2314808A - Cassette location in a printing device

Info

Publication number: GB2314808A
Application number: GB9614123A
Authority: GB
Inventors: Geert Heyse; Graham Scott Gutsell
Original assignee: Esselte NV
Current assignee: Esselte NV
Priority date: 1996-07-05
Filing date: 1996-07-05
Publication date: 1998-01-14
Also published as: GB9614123D0; EP0816104A2

Abstract

A tape holding case (37, fig.2) for a printing device (1, fig.1)has a unitary casing (37, fig.2) which defines a sleeve extending inwardly of the tape holding case (37, fig.2) over its complete height. The sleeve is located to receive an upwardly extending location element (60,fig.3) which is provided on the case of a printing device (1, Fig.1) into which the tape holding case (37, fig.2) is detachably received. The location element (60, fig.3) fixes the tape holding case (37, fig.2) against rotation and thereby locates and secures it in the receiving portion of the printing device.

Description

CASSETTE LOCATION IN A PRINTING DEVICE This invention relates to cassette

location in a printing device. It is particularly but not exclusively concerned with locating a cassette containing thermal transfer ribbon in a thermal printing device.

Thermal printing devices of the general type with which the present invention is concerned are known. They operate with a supply of tape arranged to receive an image and means for transferring an image onto the tape. In one known device, disclosed in EP 0573187, a first tape holding case or cassette holds a supply of image receiving tape and a second tape holding case or cassette holds a supply of an image transfer ribbon. The image receiving tape and the transfer ribbon are passed in overlap through a printing zone of the printing device. At the print zone, a thermal printhead cooperates with a platen to transfer an image from the transfer ribbon to the tape. The image receiving tape comprises an upper layer for receiving an image which i s secured to a releasable backing layer by a layer of adhesive. Other types of image receiving tape are possible.

In one system described in EP 0322918, the tape holding case houses a supply of a transparent image receiving tape and a supply of an image transfer ribbon. The tape holding case also houses a supply of backing tape which comprises a carrier layer having an adhesive layer on its underside to which is secured a releasable backing sheet and an adhesive layer on its upper side which can be secured to the image receiving tape after an image has been printed thereon. In this device, the image is printed onto the image receiving tape as a mirror image which, when viewed through the image receiving tape, is the correct way round. With this device, the print is protected when the label is used.

In EP-A-0322918, a common tape holding case houses the image receiving tape, the image transfer ribbon and the backing tape. It would however be possible to provide a separate cassette for the image transfer ribbon. In EP 0573187, the separate cassettes are located on opposed sides of the printing zone in respective cassette receiving portions of the printing device. The first cassette receiving portion receives the first tape cassette housing the image transfer ribbon. The second cassette receiving portion receives a second cassette housing the image receiving tape. With this arrangement, the first and second tape holding cases can be individually removable and replaceable whereby different combinations of ink ribbon and image receiving tape can be selected.

It is important with such an arrangement that when the cassettes are inserted into the printing device, the image transfer ribbon is correctly aligned with the image receiving tape at the print zone. It will be clear that guide elements for the ribbon can only be located at best on either side of the print zone, because they must not interfere with printing activity. Moreover, the image transfer ribbon can be flimsy and difficult to guide.

Furthermore, in some printing devices features have been introduced which rely on the thermal transfer ribbon cassette actuating various switching elements within the cassette receiving portion. Typically, these switching elements are biased and therefore increase the forces acting on the cassettes in normal use. one example is described in EP 0607023, which describes a switch actuated by the ink cassette to ensure that it is present. This switch is located in the cassette receiving portion of the printing device, and the cassette has to actuate a switch component when it is inserted.

Another example is described in our copending British Patent Application entitled "A Drive Mechanism for Tape" (PWF Ref. 80382), where insertion of an ink ribbon cassette causes selective different gear trains to be introduced to alter the torque applied to the ink ribbon in dependence on its width. This too increases the reactive forces on the cassette in normal use.

Figures 4A and 4B illustrate the effects of improper location and securement of a cassette. Figure 4A illustrates a cassette 37 mounted on a support location 54 of a baseplate in a printing device. Thermal transfer ribbon 12 can be seen exiting from the cassette 37 on the left hand side in Figure 4A and passing through a printing mechanism consisting of a rotatable platen 8 and a thermal printhead 16. When the cassette is properly aligned and located, as shown in Figure 4A, the thermal transfer ribbon 12 is fed through the printing mechanism with correct tension at top and bottom parts of the ribbon and thus provides a good uniform print quality. However, if the cassette is caused to lif t up out of the cassette bay as shown in Figure 4E, so that it is no longer properly supported, then the thermal transfer ribbon 12 passes through the printing mechanism with differing tensions at its top and bottom parts. In particular, the top region of a thermal transfer ribbon 12 can become slack which can allow slippage to occur. This causes a deterioration in print quality.

It is therefore desirable to locate the cassette housing the image transfer ribbon securely in its proper location, with the image transfer ribbon correctly aligned at the print zone.

According to one aspect of the present invention there is provided a printing device having detachably received therein a tape holding case holding a supply of tape for performing printing operations; wherein the printing device comprises a receiving portion having a base on which is mounted an upwardly extending location element; and wherein the tape holding case has a unitary casing portion which defines a sleeve extending inwardly of the tape holding case over substantially its complete height, the sleeve being located to receive the location element - 4 over substantially its full length and to fix it against rotation thereby to substantially locate and secure the tape holding case in the receiving portion.

Preferably, the base provides at least one support surface for the tape holding case. This can take the form of stepped locations to receive a base part of the tape holding case.

The printing device will normally include a printing mechanism located at a print zone of the printing device for performing said printing operations. In that event, the location element is preferably located in the vicinity of said print zone. In this position it serves to align the thermal transfer ribbon at the most important location, that is where printing is to be effected.

The printing device can include a moulding which defines the receiving portion and which is supported with respect to the base and through which the location element extends. The purpose of this moulding is to conceal mechanical components of the printing device and to improve its appearance. However, it is undesirable for the moulding itself to support the tape holding case because the moulding itself can become misaligned with respect to the case of the printing device.

In the described embodiment, the location element tapers from a wide bottom part to a narrow top part and the sleeve is in contact with the location element at least at said top and bottom parts. In this manner, the cassette is fixed against rotation about the location pin.

The invention is particularly applicable for the case where the tape holding case contains thermal transfer ribbon. The tape holding case can have further externally located guide elements for guiding the thermal transfer ribbon through the print zone.

As in EP 0573187, the receiving portion of the printing device can also detachably receive a second tape holding case holding a supply of image receiving tape on which an image is to be printed.

The invention also provides in another aspect a printing device for detachably receiving a tape holding case holding a supply of tape for performing printing operations; wherein the printing device comprises a receiving portion having a base which provides at least one supporting surface for the tape holding case and on which is mounted a location element which extends upwardly to extend over substantially the complete height of the tape holding case to fix it against rotation thereby to substantially locate and secure the tape holding case in the receiving portion.

The invention also provides in another aspect a tape holding case for use in a printing device, the tape holding case comprising: a supply of thermal transfer ribbon extending between a supply spool and a take-up spool within the case; external guide elements for guiding the thermal transfer ribbon externally of the case along a predetermined path; a unitary casing portion which supports the supply spool and take-up spool and which defines an integral sleeve extending inwardly of the tape holding case over substantially its complete height.

For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made by way of example to the accompanying drawings in which:

Figure 1 is a plan view showing two cassettes inserted in a printing device; Figure 2 is a plan view of a cassette housing a thermal transfer ribbon; Figure 3 is a section taken along line III-III of Figure 2, along the path illustrated with a broken line; and Figures 4A and 4B illustrate the effect of misalignment of a cassette in a printing device.

Figure 1 shows in plan view two cassettes arranged in a printing device 1. The upper cassette 2 is located in a first cassette receiving portion 26 and contains a supply of image receiving tape 4 which passes through a print zone 3 of the printer to an outlet 5 of the printer. The image receiving tape 4 comprises an upper layer for receiving a printed image on one of its surfaces and having its other surface coated with an adhesive layer to which is secured a releasable backing layer. The cassette 2 has a recess 6 f or accommodating a platen 8 of the printer, and guide portions 22,24 for guiding the tape 4 through the print zone. The platen 8 is mounted for rotation within a cage moulding 10. As an alternative, the platen 8 could be mounted for rotation on a pin. In either case, the platen 8 is mounted relative to casework of the printing device defining the cassette receiving portion.

The lower cassette 37 is located in a second cassette receiving portion 28 and contains a thermal transfer ribbon 41 which extends from a supply spool 30 to a take-up spool 32 within the cassette 37. The thermal transfer ribbon 12 extends through the print zone 3 in overlap with the image receiving tape 4. That is, it extends from the supply spool 30 past guide pins 40,42,44 which define the track of the thermal transfer ribbon from the supply spool 30 to the print zone. The cassette 37 has a recess 14 for receiving a printhead 16 of the printer and guide portions 34,36 for guiding the ink ribbon 12 through the print zone 3. The thermal transfer ribbon 41 is then taken up on the take-up spool 32 and drawn back into the cassette over guide pin 46. The printhead 16 is mounted with respect to the casework of the print device and is movable between an operative position, shown in Figure 1, in which it is in contact with the platen and holds the thermal transfer ribbon 12 and the image receiving tape in overlap between the printhead and the platen and an inoperative position in which it is moved away from the platen to release the thermal transfer ribbon and image receiving tape. In the operative position, the platen is rotated to cause image receiving tape to be driven past the printhead and the printhead is controlled to print an image onto the image receiving tape by thermal transfer of ink from the ribbon 12. The printhead is a conventional thermal printhead having an array of pixels each of which can be thermally activated in accordance with the desired image to be printed.

The printing device has a lid which is not shown but which is hinged along the rear of the cassette receiving portion and which covers both cassettes when in place.

A motor drives the platen 8 to pull tape through the print zone and sequential columns of data are printed on the image receiving tape 4 to f orm an image. The platen 8 drives the image receiving tape through the print zone under the action of its own rotation. The rotation of the platen and the energisation of the printhead 16 are controlled by a microprocessor as described in our European Patent Application Publication Nos. 0578372 and 0580322 the contents of which are herein incorporated by reference.

Figure 2 and 3 show in more detail how the ink ribbon cassette 37 is supported in the cassette receiving portion of the printing device. The casing shown in full and denoted 37 is for an ink ribbon housing ink ribbon of the width of 28mm. The dotted line denoted 37' denotes how the floor of the casing differs for a cassette housing a narrower ink ribbon, for example 19mm wide. It will be clear that the width of the ink ribbon is measured in the upwards direction in Figure 3. The cassette 37 has recessed portions 48,50 at its corners which rest on ledges or stepped portions 52,54 which form part of the baseplate of the printing mechanism. A cassette location pin 53 helps to locate the cassette relative to the baseplate, but does not serve to fix the cassette against upward forces. For the 19mm wide ribbon, the floor of the casing itself sits on these ledges 52,54. Reference numeral 56 denotes a plastic moulding for the printing device which is inserted into the cassette receiving portion predominantly to conceal and protect mechanical components of the printing device and also for the sake of appearances. The receiving portion of the printing device includes a capstan 57 for receiving the take-up spools 30 of the cassette. The take-up spool can thus be driven via its capstan 57.

In addition to the steps or ledges 52,54, the baseplate of the printing mechanism is provided with an upwards extension 58 on which is mounted a cassette locating pin 60. The pin 60 has a cylindrical base portion 62, which extends into a tapered portion 63, terminating in a narrower tip 64. The pin 60 is accommodated within a sleeve 66 which is an integral part of the casing of the cassette 37. As can readily be seen from Figure 3, the cassette location pin 60 extends substantially the full height of the cassette. This in itself distinguishes it from conventional guiding or locating elements for cassettes, which are there merely f or the purposes of locating the cassette and are not intended to securely fix it.

Moreover, the pin 60 is a close fit within the sleeve 66, and is substantially in contact with it at its lower portion 62 and upper portion 64. As can be seen in Figure 3, the sleeve 66 terminates in a roof 68 with a narrow aperture 68a, through which the tip 64 of the pin extends substantially in contact therewith. Thus rotation of the cassette relative to the pin 60 is prevented.

This means that the pin securely fixes the cassette when it is inserted into the printing device.

As can be seen most clearly from Figure 1, the cassette location pin 60 is advantageously located in the vicinity of the print zone, so that the cassette is fixed at precisely the location where correct alignment of the image transfer ribbon is most critically needed. Thus, the pin serves to add rigidity to the cassette, particularly against possible rotational motion upwards from the cassette receiving portion.

It is also to be noted that by mounting the pin on the baseplate of the printing mechanism, rather than on the plastic moulding which otherwise constitutes the floor of the cassette receiving portion, the pin is more securely and accurately mounted with respect to the printhead and platen, which are also mounted on the casework of the printing device.

Claims

CLAIMS:

1. A printing device having detachably received therein a tape holding case holding a supply of tape for performing printing operations; wherein the printing device comprises a receiving portion having a base on which is mounted an upwardly extending location element; and wherein the tape holding case has a unitary casing portion which defines a sleeve extending inwardly of the tape holding case over substantially its complete height, the sleeve being located to receive the location element over substantially its full length and to fix it against rotation thereby to substantially locate and secure the tape holding case in the receiving portion.

2. A printing device according to claim 1 wherein the base provides at least one support surface for the tape holding case.

3. A printing device according to claim 1 or 2 which comprises a printing mechanism located at a print zone of the printing device for performing said printing operations, said location element being located in the vicinity of said print zone.

4. A printing device according to claim 1, 2 or 3 which comprises a moulding defining the receiving portion supported with respect to the base and through which the location element extends.

5. A printing device according to any of claims 1 to 4 wherein the location element tapers from a wide bottom part to a narrow top part and wherein the sleeve is in contact with the location element at least at said top and bottom parts.

6. A printing device according to claim 2 or any of claims 3 to 5 when dependent thereon wherein the tape in the tape holding case is thermal transfer ribbon and wherein the tape holding case has externally located guide elements for guiding the thermal transfer ribbon through the print zone.

7. A printing device according to claim 6 wherein the receiving portion also detachably receives a second tape holding case holding a supply of image receiving tape on which an image is to be printed.

8. A printing device for detachably receiving a tape holding case holding a supply of tape for performing printing operations; wherein the printing device comprises a receiving portion having a base which provides at least one supporting surface for the tape holding case and on which is mounted a location element which extends upwardl- to extend over substantially the complete height of the tape holding case to fix it against rotation thereby to substantially locate and secure the tape holding case in the receiving portion.

9. A printing device according to claim 8 which comprises a printing mechanism located at a print zone of the printing device for performing said printing operations, said location element being located in the vicinity of said print zone.

10. A printing device according to claim 8 or 9 which comprises a moulding defining the receiving portion supported with respect to the base and through which the location element extends.

11. A printing device according to any of claims 8 to 10 wherein the location element tapers from a wide bottom part to a narrow top part.

12. A tape holding case for use in a printing device, the tape holding case comprising: a supply of thermal transfer ribbon extending between a supply spool and a take-up spool within the case; external guide elements for guiding the thermal transfer ribbon externally of the case along a predetermined path; a unitary casing portion which supports the supply spool and take-up spool and which defines an integral sleeve extending inwardly of the tape holding case over substantially its complete height.

13. A tape holding case according to claim 12 wherein the sleeve defines a wide aperture at its base part and a narrow aperture at its top part for receiving and fixing a tapered location pin of a printing device.