EP0794066A1 - Means to detect a ribbon cassette in a tape printing apparatus - Google Patents

Abstract

The detector is for a belt printer with a cassette receiver cavity (2) into which a cassette can be inserted containing a belt to be printed. The printing button (32) and counter-pressure roll (6) can be brought to the service position ready to print. The detector can bring the printing button and the counter-pressure roll into connection in the service position when there is no cassette in the cassette receiver cavity. The printing button or counter-pressure roller may be fixed in a holder.

Description

The invention relates to a tape printing device according to the preamble of claim 1.

Tape printing devices of the type with which the present invention is concerned are known. They work with a tape supply to be printed on - with an image - and means for transferring the image to the tape. In one embodiment, a tape holder housing or cassette contains a supply of the tape to be printed and a supply of an image transfer tape. The tape to be printed and the image transfer tape (ink ribbon) are guided one above the other through a printing area of the tape printing device. A tape printing device that works with a bracket housing of this type is e.g. in EP-A-0267890 (Varitronics, Ink.). Other printing devices have been made in which letters are transferred to an image receiving belt by means of a dry lettering or dry film printing process. In all of these printing devices, the structure of the tape to be printed is essentially the same; i.e. it comprises an upper layer to be printed with an image which is attached to a peelable backing layer by means of an adhesive layer.

In another type of tape printing device, as described, for example, in EP-A-0322919 (Brother), a tape holder housing contains a supply of tape to be printed, a supply of image transfer tape and a supply of self-adhesive backing tape. The backside tape has an adhesive layer to be brought into contact with the image-receiving layer, a substrate layer and a second adhesive layer which is covered with a peelable backing layer. The letters are printed on the transparent image-receiving layer as a mirror image.

In another tape printing device, e.g. in EP-A-0487313 (Esselte Dymo N.V.), a tape holder housing contains a supply of image receiving tape and a supply of image transfer tape, the image receiving tape having the same construction as described in connection with EP-A-0267890 above.

In order to carry out a printing process, a thermal print head and an associated counter-pressure roller have to be brought into an operating position in the known tape printing devices, in which the ribbon to be printed is in contact with the counter-pressure roller and the print head is in contact with the ribbon or (as a rule) with an ink ribbon. In the operating position, the print head and the counter-pressure roller exert a pressure force on one another which is required for printing. In order to be able to insert another ribbon, means are provided for moving the print head and the counter-pressure roller into an inoperative position in which they are spaced apart. Specifically, the print head or the counter-pressure roller can be moved. The movement can be coupled with a cover which closes the cassette receiving space of the tape printing device to the outside.

A disadvantage of the known tape printing devices is that there is contact between the platen roller and the printhead even when no cassette is inserted and the lid is closed. Due to the contact pressure of the print head against the elastic counter-pressure roller, the latter deforms much more than when a tape is inserted. It is obvious, that the high print quality is not to be expected with a counter-pressure roller that is not exactly circular cylindrical.

Starting from the prior art, the object of the invention is to provide a tape printing device in which good print quality can always be expected.

According to the invention the problem is solved by the teaching of claim 1.

The main idea of the invention is to check whether a cassette has been properly inserted into the cassette receiving space of the tape printing device and to only allow the print head and the counter-pressure roller to move into their operating position when a cassette is inserted. Otherwise, if there is no cassette, movement of the print head and the counter-pressure roller into the operating position is prevented, so that no contact between the counter-pressure roller and the print head is possible.

The advantages of the invention consist primarily in the fact that there is no longer any risk of undesired deformation of the counter-pressure roller, so that perfect print quality is always guaranteed.

Furthermore, it is proposed to mount the printhead or the counter-pressure roller in a manner known per se on a holder which can be moved between a position in which the printhead and counter-pressure roller are in the operating position and a position in which the printhead and counter-pressure roller are in the non-operating position. The means for detecting an inserted cassette are then designed such that they limit the movement of the holder in such a way that the holder cannot move into the position corresponding to the operating position as long as no cassette is inserted. Otherwise, when the cassette is inserted, the limitation of the movement of the holder is natural ineffective, so that the print head and counter-pressure roller can be brought into the operating position as usual. It should also be noted here that when a cassette is removed, the holder must always be in a position which corresponds to an inoperative position of the print head and counter-pressure roller, since otherwise the cassette cannot be removed at all. For this reason, it is sufficient to limit the movement of the holder from the inoperative position towards the operating position.

It is also sufficient to limit the movement of the holder so far when the cassette is not inserted that the print head and the counter-pressure roller do not come into contact with one another, so that the undesired deformation of the latter is prevented. It would alternatively be conceivable, but not absolutely necessary, to lock the holder in a position corresponding to the inoperative position.

For structural reasons, it is preferred to mount the holder so that it can pivot about a pivot point.

In concrete terms, it is recommended that the means for detecting a cassette inserted into the cassette receiving space be equipped with a movable element that can be moved by an inserted cassette. The element can take two positions: the first position is reached when no cassette is inserted; The printhead and the platen roller cannot get into their operating position. If, however, a cassette is properly inserted, the element assumes the second position, in which an operating position of the print head and counter-pressure roller can be reached. The element is usually slidably or rotatably mounted.

In order to ensure that the element arrives in the corresponding position in which the movement of the Bracket is limited, a corresponding spring can be used.

For the lateral alignment of the element in an inserted cassette, an opening or recess can be made in the latter. The element then has a corresponding head which penetrates into the opening.

Since the element is in contact with an inserted cassette, it must be (in part) in the cassette receiving space. The rest of the mechanism, such as the movable holder for the printhead or the counter-pressure roller, is usually not located in the cassette holding area, but beyond a base plate. Therefore, the element preferably penetrates a corresponding opening in the base plate, in which it can also be mounted.

The invention further comprises in combination with one another: a tape printing device with a cassette receiving space, into which a cassette can be inserted, which contains a tape to be printed on, in the case of the tape printing device a printhead and a counter-pressure roller being able to be brought into an operational position ready for printing relative to one another, means for detection there is a cassette in the cassette accommodating space which prevents the printhead and the platen from moving into the operating position when no cassette is inserted in the cassette accommodating space; and a cassette inserted in or for insertion into the cassette receiving space, which cooperates with the means for detecting a cassette, so that the printhead and the counter-pressure roller can be brought into the operating position when the cassette is inserted.

Figur 1:

Ein Banddruckgerät mit einer eingesetzten Kassette;

Figur 2:

Einen im Kontakt mit einer Gegendruckwalze stehenden Druckkopf ;

Figur 3:

Einen Befestigungsmechanismus für einen Druckkopf;

Figur 4:

Einen arretierten Befestigungsmechanismus für einen Druckkopf;

Figur 5:

Einen Arretierungsmechanismus bei fehlender Kassette;

Figur 6:

Einen Arretierungsmechanismus bei eingelegter Kassette.

An embodiment of the invention is explained in more detail below with reference to the drawings. They show a schematic representation in

Figure 1:

A tape printer with an inserted cassette;

Figure 2:

A printhead in contact with a platen roller;

Figure 3:

A printhead mounting mechanism;

Figure 4:

A locked printhead mounting mechanism;

Figure 5:

A locking mechanism when the cassette is missing;

Figure 6:

A locking mechanism when the cassette is inserted.

Figure 1 illustrates the top view of a cassette receiving space of a tape printing device. The cassette receiving space is represented by the dashed line 2. It contains a (thermal) print head holder 4 and a counter-pressure roller 6, which interact and define a printing zone P in a manner known per se. The print head holder 4 is pivotally mounted about a fulcrum 8, so that the print head can be brought into contact with the print roller 6 and can be moved away from it in order to be able to remove and replace a cassette 10.

A cassette inserted in the cassette accommodating space 2 is provided with the reference number 10. The cassette 10 contains a supply roll 12 with a tape 14 to be printed, which comprises an image-receiving layer 31 which is attached to a rear-side layer 32 by means of an adhesive layer. The tape 14 to be printed is guided through a cassette 10 (not shown) through the cassette 10 and leaves it shortly after the printing zone through an outlet O and then reaches a cutting location C. The cassette 10 also contains a ribbon supply roll 16 and a ribbon take-up roll 18. The ribbon 20 is guided by the ribbon supply roll 16 through the printing zone P and wound on the ribbon take-up reel 18. The ribbon 14 to be printed passes through the printing zone P together with the ink ribbon 20, its image-receiving layer 31 being in contact with the ink ribbon 20.

In the tape printing device shown in FIG. 1, the counter-pressure roller 6 is driven so that it rotates and guides the tape 14 to be printed through the printing zone P during the printing process. The tape 14 is printed and guided from the printing zone P to the cutting zone C. The cutting zone C is provided on the wall of the cassette 10 near the printing zone P. Since the belt 14 is pulled out of the cassette 10 by the drive of the counter-pressure roller 6, no further belt drive mechanism is required; the cutting zone C is located close to the printing zone. The part of the wall of the cassette 10 which defines the cutting zone C is identified by the reference number 22. A slot 24 is included in this section 22 of the wall. The tape 14 to be printed is moved from the printing zone P to the cutting zone C, where it is supported by opposite wall sections on both sides of the slot 24.

The tape printing device comprises a cutting mechanism, which is identified by reference numeral 26. This cutting mechanism 26 comprises a cutting support 28 which carries a blade 30. Blade 30 cuts ribbon 14 and then enters slot 24. In Figure 1 the cutting mechanism 26 is shown in its ready to cut condition, i.e. the blade 30 is spaced from the belt 14. This enables the free end face of the belt 14 to be transported through the cutting zone C without running the risk of getting caught on it or being deflected.

The disadvantage of conventional tape printing devices can be seen in FIG. If no cassette 10 is inserted, that is to say no tape 14 is present between printhead 32 and counter-pressure roller 6, presses the print head 32 against the counter-pressure roller 6, which is made of an elastic material such as rubber, so that the latter can deform permanently. The undesirable result is an unsatisfactory printing quality caused by the non-round, deformed counter-pressure roller 6. If a cassette 10 is inserted and a tape 14 is between the print head 32 and the counter-pressure roller 6, the pressure force is distributed over a larger area due to the relatively rigid tape 14; contact of the counter-pressure roller 6 with any sharp edges of the print head 32 is not possible, so that the undesired deformation of the counter-pressure roller is not to be feared.

FIG. 3 shows a view (shown with reference to FIG. 1 from below) of a print head holder 4, which can be pivoted between the two positions 34, 36 around the pivot point 8 in a manner known per se. In the first position 34 shown in broken lines, the pivotable print head holder 4 is positioned such that the print head 32 is spaced apart from the counter-pressure roller 6. In the second position 36, represented by closed lines, the printing position, the print head holder 4 is pivoted in the direction of arrow 40 in a clockwise direction so that the print head 32 rests on the counter-pressure roller 6. The pressure force of the print head 32 is generated by means of a spring 38 which is fixed to the end of the two-armed print head holder 4 opposite the print head 32. The pivoting movement is usually carried out by a hinged lid which closes the cassette receiving space 2 to the outside and which interacts with the thermal print head holder 4, so that the print head holder 4 is in position 34 when the cover is open, while it is pivoted to position 36 when the cover is closed . A corresponding mechanism is disclosed in EP-A-487 313, the content of which is incorporated by reference. It should be noted that the arm of the print head holder 4, which is drawn to the right of the pivot point 8, is arranged below the cassette receiving space 2 of the tape printing device, so that it cannot be seen in FIG. 1 is - it is covered by the floor of the cassette receiving space 2.

FIG. 4 shows the same view as in FIG. 3; however, a printhead holder stop 46 is provided against which the printhead holder 4 rests in the area of its right arm opposite the printhead 32. The print head holder stop 46 prevents the spring 38 from moving the print head holder 4 into position 36. The latter is thus in a position 42 in which the print head 32 is spaced from the counter-pressure roller 6, so that the latter cannot deform. The position 42 can at least approximately coincide with the position 34, but can also correspond to a pivoting angle of the print head holder 4, which corresponds to an intermediate position between the positions 34 and 36, insofar as the print head 32 is not in contact with the counter-pressure roller 6.

It can be seen from the side view shown in FIG. 5 that the print head holder stop 46 is essentially U-shaped. A shorter arm shown on the right serves to limit the pivoting movement of the print head holder 4, while the second, likewise vertically oriented arm of the print head holder stop 46 penetrates a base plate 48, which is provided below the bottom of the cassette receiving space 2. The base plate 48 runs parallel to the bottom of the cassette receiving space 2. On the upper side of the second arm of the print head holder stop 46, which is located within the cassette receiving space 2, a cylindrical head 50 is provided, which is provided with a circumferential, annular shoulder 51 at a distance from its end face is. The shoulder 51 serves as a stop for a helical spring 52 which runs around the second arm 52 and bears against the base plate 48 at the other end. The printhead holder stop 46 is mounted in the base plate 48 penetrated by it so that it can be displaced in the vertical direction. In FIG. 5, the print head holder stop 46 lies on the print head holder 4 so that it is in position 42 according to FIG.

In Figure 6, a cassette 10 is inserted into the cassette receiving space 2. It has an opening 53 into which the head 50 of the second arm of the print head holder stop 46 penetrates. The opening 53 causes the head 50 to be guided laterally and prevents cassettes 10 which do not fit from being inserted. Since the ring 51 rests on the cassette 10, it is pressed downwards in the direction of the base plate 48. Thus, the print head holder stop 46 is displaced vertically downward (relative to FIG. 5), so that the coil spring 52 is compressed and the first, shorter arm of the print head holder stop 46 allows the print head holder 4 to move between the first position 34 and the second position 36. Since a cassette 10 is inserted, there are no concerns about pressing the print head 32 against the counter-pressure roller 6. The pivoting movement of the print head holder 4, which is brought about, for example, by a cover of the cassette receiving space 2 or a corresponding lever, can now run as shown in FIG.

After the cassette 10 has been removed, the helical spring 52 moves the print head holder stop 46 back into the position 42 shown in FIG. 5, so that no contact between the counter-pressure roller 6 and the print head is possible.

Claims (10)

Tape printing device with a cassette receiving space (2), into which a cassette (10) can be inserted, which contains a tape (14) to be printed on, a print head (32) and a counter-pressure roller (6) being able to be brought into an operational position with readiness for printing relative to one another, characterized in that means for detecting a cassette (10) are present in the cassette receiving space (2) and prevent the printhead (32) and the counter-pressure roller (6) from being brought into the operating position when no cassette (10) is in the cassette receiving space (2) is inserted. Tape printing device according to claim 1, characterized in that the print head (32) or the counter-pressure roller (6) is fastened to a holder which is between a position (36) in which the print head (32) and counter-pressure roller (6) are in the operating position, and a position (34) in which the print head (32) and counter-pressure roller (6) are in the non-operating position, and that the means for detecting a cassette (10) inserted into the cassette receiving space (2) limit the movement of the holder Position can be brought. Tape printing device according to claim 2, characterized in that the means for detecting a cassette (10) inserted into the cassette receiving space (2) when the cassette (10) is not inserted, only a movement of the holder between a position (34) in which the print head (32 ) and the counter-pressure roller (6) are in the inoperative position, and a position (42) in which the print head (32) and the counter-pressure roller (6) are not in contact. Tape printing device according to claim 2 or 3, characterized in that the holder is pivotally mounted about a pivot point (8). Tape printing device according to one of Claims 1 to 4, characterized in that the means for detecting a cassette (10) inserted into the cassette receiving space (2) comprise a movable element which can be moved by an inserted cassette (10). Tape printing device according to claim 5, characterized in that the element is mounted displaceably. Tape printing device according to claim 5 or 6, characterized in that the element is brought into a position limiting the movement of the holder by a spring (52) when the cassette (10) is not inserted into the cassette receiving space (2). Tape printing device according to one of claims 5 to 7, characterized in that the element has a head (50) which is positioned in an opening (53) of a cassette (10) inserted into the cassette receiving space (2). Tape printing device according to one of claims 5 to 8, characterized in that the element penetrates a base plate (48). In combination with one another: A tape printing device with a cassette receiving space (2), into which a cassette (10) can be inserted, which contains a tape (14) to be printed on, in the case of the tape printing device a print head (32) and a counter-pressure roller (6) relative to one another can be brought into an operating position ready for printing, means are provided for detecting a cassette (10) in the cassette receiving space (2), which prevent the print head (32) and the counter-pressure roller (6) from being brought into the operating position if no cassette (10) is in the Cassette receiving space (2) is inserted; and a cassette (10) inserted in or for insertion in the cassette receiving space (2), which cooperates with the means for detecting a cassette (10), so that the printhead (32) and the counter-pressure roller (6) can be moved into the operating position when the cassette (10) is inserted.

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