EP0535840A1

EP0535840A1 - Platen roller

Info

Publication number: EP0535840A1
Application number: EP92308576A
Authority: EP
Inventors: Shunji c/o Brother Kogyo K.K. Shiota
Original assignee: Brother Industries Ltd
Current assignee: Brother Industries Ltd
Priority date: 1991-09-20
Filing date: 1992-09-21
Publication date: 1993-04-07
Also published as: JPH0528645U

Abstract

A printing system for printing characters/symbols on a tape-like member (11). The printing system includes a cassette (10) for accommodating the tape-like member (11), a print head (20), a platen roller (23) urged to contact said print head, and a feeding mechanism (22, 18) for feeding the tape-like member to pass through the nip between the print head and the platen roller. The platen roller consists of at least two roller members (23A, 23B) coaxially arranged one on another, respective one of the roller members being capable of being rotated independently.

Description

The present invention relates to printing apparatus for printing images (characters/symbols and the like) on one of a plurality of tapes of varying widths.
Conventionally, this kind of a tape printing apparatus is arranged so that a platen roller is elastically pressed against a fixed thermal head. A tape and a thermal transfer ribbon are fed through a nip between the platen roller and the thermal head. Characters, symbols and the like are printed on the tape by the thermal head through the thermal transfer ribbon.
Generally, the width of the tape, the width of the thermal transfer ribbon, and the width of the platen are substantially the same. When this is so, the thermal head does not directly contact the platen.
If the tape on which characters and symbols are to be printed has a width narrower than the width of the thermal head and the platen roller, a part of the thermal head directly contacts the platen roller. In this case, due to frictional resistance at the contact between the thermal head and the platen, the rotational load imposed on the platen roller increases and slippage of the tape may occur. To cope with this problem, a strong spring biasing unit is sometimes employed to increase the force of contact of the platen roller against the thermal head. Alternatively, a strong motorforfeeding the tape is employed to avoid slippage of the tape.
However, with the constructions described above, a disadvantage is that the strong spring biasing unit or motor increases the complexity of, and number of parts of, the apparatus, increasing the time taken to assemble the apparatus and adding to the cost.
In order to avoid direct contact between the thermal head and the platen, a thermal transfer ribbon having a width substantially equal to the width of the thermal head and platen roller may be used, even when the width of the tape is narrower than the width of the thermal head and the platen roller. In this case, a disadvantage is that a portion of the wide thermal transfer ribbon is used only for reducing frictional resistance between the thermal head and the platen roller. This is wasteful. Furthermore, the size of the ribbon cassette in which the thermal transfer ribbon is accommodated is increased accordingly. This is uneconomical and increases costs as with the former method.
According to a first aspect of the present invention there is provided a platen roller for use in a printing apparatus, said platen roller being, in use, arranged to be biased against a print head of the printing apparatus, said platen roller comprising at least two coaxial and independently rotatable roller members.
Each platen roller member may be mounted on a shaft through an individual collar, said collars being provided with end flanges to space the platen roller members apart axially.
According to a second aspect of the present invention there is provided a printing apparatus for printing on a tape-like member, the apparatus comprising a print head, a platen roller in accordance with the first aspect of the present invention, and feed means for feeding the tape-like member to pass through a nip between the print head and the platen roller.
The print head is preferably a thermal print head, with the feed means arranged to feed a thermal transfer ribbon together with the tape-like member in alignment with the thermal print head.
The tape feed means is preferably arranged to feed an adhesive tape together with the tape-like member and to adhere the adhesive tape to a printed surface of the tape-like member. The feed means may comprise at least one rotatably driveable roller.
The apparatus is preferably adapted to print on a tape-like recording members of different widths, the axial extent of one of the platen roller members corresponding to the width of a narrower one of the tape-like recording members, and the axial extent of said at least two platen roller members corresponding to the width of a wider one the tape-like recording members.
According to a third aspect of the present invention there is provided a printing system for printing on a tape-like member, the system comprising a printing apparatus in accordance with the second aspect of the present invention and a cassette accommodating the tape-like recording member.
Where provided, the thermal transfer ribbon and the adhesive tape are preferably of substantially the same width as the tape-like member. The adhesive tape is, preferably, a double-sided adhesive tape.
An embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Fig. 1 is a perspective view of an embodiment of tape printing apparatus;
Fig. 2 is a plan view of the tape printing apparatus of Fig. 1 with the upper case of the apparatus and the upper cover of the tape cassette removed;
Fig. 3 is an enlarged cross sectional view of the platen roller of Fig. 1;
Fig. 4 is a perspective view of a print mechanism and tape feed mechanism of the apparatus of Fig. 1, showing a wide tape; and
Fig. 5 is a perspective view of a print mechanism and tape feed mechanism of the apparatus of Fig. 1 showing a narrow tape.

Fig. 1 is a perspective view of a tape printing apparatus. The tape printing apparatus 1 includes an upper case 2, a lower case 3, a keyboard 4, a character/symbol input dial 5, and a liquid crystal display 6 disposed on the upper surface of the upper case 2. The keyboard 4 is provided with:
a power supply switch key 7 for turning ON and OFF a power supply for the tape printing apparatus; and
a print switch key 8 for starting a printing operation using a thermal head 20, as will be described below.
The character/symbol input dial 5 is used to selectively input desired letters, characters and symbols. The liquid crystal display 6 is used to display the letters, characters and symbols inputted through the input dial 5.
Fig. 2 is a plan view of the main portion of the tape printing apparatus shown with the upper case 2 and the upper cover of a tape cassette 10 removed. The tape cassette 10 is disposed on the lower case 3 and rotatably supports a feed spool, wind spool and the like for various tapes.
The tape cassette 10 is detachably mounted to a print mechanism including the thermal head 20 of the tape printing apparatus 1. The tape cassette 10 contains:

(1) a film tape spool 12 around which a transparent film tape 11 is wound;
(2) a ribbon feed spool 14 around which a thermal transfer ribbon 13 is wound with the ink surface thereof facing towards the inside;
(3) a ribbon wind spool 15 forwinding the thermal transfer ribbon 13 drawn from the ribbon feed spool 14;
(4) a double-sided adhesive tape spool 17 around which is wound a double-sided adhesive tape 16 with a releasable paper adhered to one side thereof and facing to the outside, the releasable paper having a width substantially the same as that of the film tape 11; and
(5) an alignment roller 18 for aligning the double-sided adhesive tape 16 with the film tape 11. The above-described spools are rotatably supported by an upper cover and support unit (not shown).

The ribbon wind spool 15 and alignment roller 18 (which, together with a feed roller 22 to be described later constitute a feed mechanism for the film tape 11 and double-sided adhesive tape 16) may be driven in rotation by a well-known pulse motor thorough a suitable power transmission mechanism.
The thermal head 20 fixed to the lower case 3 is disposed in a recessed portion 19 defined in the tape cassette 10. The feed roller 22 and a platen roller 23 are disposed in confrontation on a side opposite to the alignment roller 18 and thermal head 20 respectively. The feed roller 22 and the platen roller 23 are disposed on a support member 21 which is rotatably supported by the lower case 3.
The support member 21 is urged by a well-known biasing member so that, when the tape cassette 10 is mounted, the platen roller 23 and the feed roller 22 are pressed against the thermal head 20 and the alignment roller 18 respectively, as shown in solid lines in Fig. 2.
The support member 21 is retracted to the position shown in dotted lines in Fig. 2 when the tape cassette 10 is detached. An example of a biasing member of this type is disclosed in US-A-5120147 issued on June 9, 1992.
Fig. 3 is an enlarged cross sectional view of the platen roller 23. The platen roller 23 is rotatably supported by a roller shaft 24 provided on the support member 21. The platen roller 23 is divided into an upper roller member 23A and a lower roller member 23B along the axial extent of the roller shaft 24. The upper roller member 23A is rotatably mounted to the roller shaft 24 through a collar 25 and the lower roller member 23B is rotatably mounted thereto through a collar 26. The collars 25, 26 are provided with flanges at their ends, the two opposing flanges at the junction between the two roller members 23A, 23B being in contact and spacing the facing ends of the roller members apart. With this arrangement, the upper roller member 23A and lower roller member 23B can rotate independently of each other about the roller shaft 24.
An operation for printing desired characters/symbols and the like on a tape with the tape printing apparatus 1 will be described below.
When the print switch key 8 of the keyboard 4 is depressed after desired characters/symbols have been inputted using the character/symbol input dial 5, a print control for printing with the thermal head 20 is started.
When the print control is started, film tape 11 is drawn from the spool 12 by the alignment roller 18 and feed roller 22, and fed towards the nip between the thermal head 20 and platen roller 23. At the same time, thermal transfer ribbon 13 is also drawn from the ribbon feed spool 14, and fed towards the nip between the thermal head 20 and platen roller 23 in a similar way to the film tape 11.
The characters/symbols are reverse printed on the film tape 11 by the thermal head 20, through the thermal transfer ribbon 13, as the film tape 11 and the thermal transfer ribbon 13 are fed. The printed film tape 11 is then fed towards the alignment roller 18 and feed roller 22, whilst the thermal transfer ribbon 13 used for the printing is wound around the ribbon wind spool 15.
Fig. 4 is a perspective view schematically showing the print mechanism (composed of the thermal head 20 and platen roller 23) and the tape feed mechanism (composed of the alignment roller 18 and feed roller 22) and shows the case in which a printing operation and tape feeding operation are carried out using a film tape 11 and a thermal transfer ribbon 13 both of a tape width substantially equal to the width of the thermal head 20 and the axial extent of the full platen roller 23 (e.g. about 24 mm wide). Fig. 5 is a perspective view similar to Fig. 4, but shows a case in which a printing operation and feed operation are carried out using a film tape 11 and thermal transfer ribbon 13 both of a tape width which is approximately 1/2 the width of the thermal head 20 and 1/2 the axial extent of the full platen roller 23 (e.g. about 12 mm wide).
In Fig. 4, the film tape 11 and thermal transferrib- bon 13 are fed as described above and are pressed against the thermal head 20 by the platen roller 23. In this condition, characters/symbols are reverse printed on the film tape 11 by the thermal head 20 through the thermal transfer ribbon 13. Because the tape widthofthe film tape 11 and thermal transferrib- bon 13 is substantially equal to the width of the thermal head 20 and the axial extent of the full platen roller 23, the film tape 11 comes into contact with the both the upper roller member 23A and lower roller member 23B across substantially their full axial extents. Thus, the thermal head 20 is substantially prevented from contracting the platen roller 23. Therefore, when the film tape 11 is fed by the alignment roller 18 and feed roller 22 on completion of printing by the thermal head 20, there is substantially no frictional resistance between the thermal head 20 and the platen roller 23. With this arrangement, the film tape 11 may be smoothly fed without undue frictional resistance.
In Fig. 5, although characters/symbols are printed on the film tape 11 by the thermal head 20 in the same way as in the Fig. 4 arrangement, only the upper roller member 23A of the platen roller 23 is involved in the printing operation due to the tape width of both the film tape 11 and the thermal transfer ribbon 13 being approximately 1/2 the total axial extent of the platen roller 23. The tape width is however approximately equal to the full axial extent of the upper roller member 23A.
The upper roller member 23A is rotated about the roller shaft 24 independently of the lower roller member 23B as the film tape 11 and the thermal transfer ribbon 13 are fed. The lower roller member 23B does not rotate and simply remains in stationary contact with the thermal head 20. Thus lower roller member does not cause frictional resistance when the film tape 11 is fed.
As described above, even if film tape 11 is used which has a tape width of approximately 1/2 the width of the thermal head 20 and 1/2 the full axial extent of the platen roller 23, there is substantially no increase in frictional resistance, allowing the tape 11 to be smoothly fed.
Further, when tape of a width approximately 1/2 the width of the thermal head 20 and 1/2 the full axial extent of the platen roller 23 is used, there is no need to use a thermal transfer ribbon 13 of a width substantially equal to the width of the thermal head 20 and platen roller 23 to try to reduce frictional resistance, in contrast to one of the prior art arrangements discussed above.
After the characters/symbols have been printed on the film tape 11 as described above, the alignment roller 18 draws out the double-sided adhesive tape 16 from the spool 17 in association with the feed roller 22, and one adhesive surface thereof is adhered in alignment to the printed surface of the film tape 11 to produce a printed tape P.
Thereafter, the tape P may be cut, by a manual or electrically-driven cutter (not shown) to cut the tape P to a predetermined length.
As described above, the tape printing apparatus 1 includes a platen roller 23 pressed against the thermal head 20, the platen roller 23 being divided into an upper roller member 23A and lower roller member 23B along the axis of the roller shaft 24. Further, the divided upper and lower roller members 23A and 23B are rotatable about the roller shaft 24 independently of each other. Thus, film tapes 11 and thermal transfer ribbons 13 of different tape widths may be used without causing problems with frictional resistance between the thermal head 20 and the platen roller 23 when the film tapes 11 and thermal transfer ribbons 13 are fed.
Further, this embodiment can avoid the need for a strong spring urging unit or motor such as is required in a conventional tape printing apparatus. This simple arrangement helps reduce the number of parts of the printing apparatus, which enables the apparatus to be assembled easily. Further, the need for a large tape cassette to accommodate a wide transfer ribbon 13 only for the purposes of reducing friction may be avoided. As a result, a less expensive tape printing apparatus may be provided.
It should be understood that the present invention is not limited to the above embodiment, and various changes and improvements may be made therein without departing from the gist of the present invention.
For example, in the foregoing description, although the platen roller 23 is divided into an upper roller member 23A and lower roller member 23B in correspondence with the two kinds of film tapes 11 and thermal transfer ribbons 13, the platen roller 23 may be of course divided into three or more portions, dependent on the tape width of the film tape 11 and the like to be used.
Although the illustrated embodiment comprises three tapes or ribbons, the apparatus is not limited to this particular arrangement. Greater or fewer numbers of tapes/ribbons may be employed. For example, although in the illustrated embodiment the alignment roller 18 adheres a double-sided adhesive tape 16 to a printed surface of a film tape 11 in association with a feed roller 22 to create a tape P, a tape integrally composed of the film tape 11 and the double-sided adhesive tape 16 may be used.
As described above, the illustrated embodiment of tape printing apparatus allows friction between a print head and a platen roller to be substantially eliminated when tapes of a smaller width than the width of the print head and the corresponding measurement of the platen roller are used. This allows the tapes to be fed smoothly using a very simple arrangement.
This invention greatly contributes to industrial im- provement/efficiency.

Claims

1. A platen roller for use in a printing apparatus, said platen roller (23) being, in use, arranged to be biased against a print head of the printing apparatus, said platen roller comprising at least two coaxial and independently rotatable roller members (23A, 23B).

2. A platen roller as claimed in claim 1, wherein each platen roller member (23A, 23B) is mounted on a shaft (24) through an individual collar (25, 26).

3. A platen roller as claimed in claim 2, wherein the collars (25, 26) are provided with end flanges to space the platen roller members (23A, 23B) apart axially on the shaft.

4. A printing apparatus for printing on a tape-like member, comprising a print head (20), a platen roller (23) as claimed in any of the preceding claims, and feed means for feeding the tape-like member (11) to pass through a nip between said print head and said platen roller.

5. A printing apparatus as claimed in claim 4, wherein said print head (20) is a thermal print head and said feed means is arranged to feed a thermal transfer ribbon (13), together with the tape-like member (11), in alignment with said thermal print head.

6. A printing apparatus as claimed in claim 4 or claim 5, wherein said feed means is arranged to feed an adhesive tape (16) together with the tape-like member (11) and to adhere the adhesive tape to the tape-like member.

7. A printing apparatus as claimed in claim 6, wherein the feed means is arranged to adhere the adhesive tape (16) to a printed surface of the tape-like member (11).

8. A printing apparatus as claimed in any of claims 4 to 7, wherein said feed means comprises at least one rotatably driveable roller to feed the tape-like member.

9. A printing apparatus as claimed in any of claims 4 to 8, wherein the apparatus is adapted to print on tape-like recording members (11) of different widths, the axial extent of one of said platen roller members (23A, 23B) corresponding to the width of a narrower one of the tape-like recording members, and the axial extent of said at least two platen roller members corresponding to the width of a wider one of the tape-like recording members (11).

10. A printing system for printing on a tape-like member, said system comprising a printing apparatus as claimed in any of claims 4 to 9 and a cassette accommodating said tape-like member (11).

11. A printing system as claimed in claim 10, when dependent on claim 5, wherein the thermal transfer ribbon (13) is of substantially the same width as the tape-like member (11).

12. A printing system as claimed in claim 10 or 11, wherein the adhesive tape (16) is of substantially the same width as the tape-like member (11).

13. A printing system as claimed in claim 12, wherein the adhesive tape (16) is a double-sided adhesive tape.