GB2113149A - Printing ribbon winding - Google Patents

Abstract

A film-type printing ribbon cassette includes a roll (4) of used ribbon in rolling driving engagement with a drive roller (5) whereby a given increment of rotation of the drive roller (5) rolls a predetermined length of ribbon onto the roll (4) and pulls a new portion of ribbon into a printing station (3). The roll (4) of used ribbon and roll (2) of new ribbon are mounted on mandrels (8,9) slidable along slot (10) in the cassette casing. An elastic band acts on the mandrel 8 basing it towards the mandrel (9), and a spacer (6) located between the mandrels transfers thrust from mandrel (8) to mandrel (9) to maintain the roll (4) in engagement with the drive roller (5). The elastic band can act solely on the mandrel (9). <IMAGE>

Description

SPECIFICATION Ribbon winding This invention relates to the winding of a ribbon of material, and is particularly applicable to the winding of a printing ribbon as hereinafter defined.

The term "printing ribbon" as used herein means a ribbon of material carrying an image producing substance which is deposited on a surface to produce the image of a character when the ribbon is laid against the surface and is struck with a member having a raised surface defining the character. Such ribbons are commonly used in typewriters, small computer output printers, teleprinters, and telex machines.

Printing ribbons of the film type which comprise a base coated with a printing ink are used extensively where high quality printing is required. Such film ribbons are not wound back and forth repeatedly as are the impregnated cloth type of ribbon, but are fed once only through the printing station of the machine in which they are used, after which they are discarded. In order to obtain the best possible efficiency for the use of such ribbons it is necessary to advance the ribbon by a predetermined distance between each strike of the character defining members. The distance by which the ribbon is advanced may be such that consecutive strikes of the character defining member overlap on the ribbon or, for the highest quality printing, may be such that each strike uses a completely new length of ribbon.

It has been conventional to advance the ribbon by the desired amount by use of pinch wheels engaging the ribbon and driven by a stepping motor. If pinch wheels are used separate means must be provided for winding the used ribbon onto a take-up spool. Typically in the prior art winding of the used ribbon is effected by way of rotating the used ribbon spool through a slipping drive device powered from the stepping motor. Winding of the spool of used ribbon draws power from the stepping motor and in order to ensure that the power drawn from the stepping motor does not become excessive it has been necessary to manufacture components associated with ribbon advancement to a high degree of accuracy.In the case where the ribbon is housed within a moulded plastics cassette this has necessitated a high standard of accuracy and careful assembly of the cassette in order to achieve satisfactory results.

According to the present invention there is provided apparatus including a ribbon which, in use of the apparatus, is wound from a roll of new ribbon through a work station to a roll of used ribbon, the apparatus comprising: a rotary drive roller which is in rolling driving engagement with the periphery of the roll of used ribbon; and means mounting the roll of used ribbon for movement relative to the drive roller to maintain said rolling driving engagement as the diameter of the roll of used ribbon increases in use.

In the preferred embodiment of the invention the rotary drive roller together with the rolls of new and used ribbon are located within a cassette, a suitable drive connection being provided between the drive roller and an associated drive spindle of the apparatus. The drive spindle will be connected to a stepping motor so that the drive spindle is rotated by a predetermined angular amount between each successive strike of the character defining member. In that the drive roller is in rolling driving engagement with the periphery of the roll of used ribbon, each equal angular rotation of the rotary drive roller will produce an equal linear advance of the ribbon.Thus, by placing the drive roller in rolling driving engagement with the periphery of the roll of used ribbon the rotary drive roller directly serves the combined function of advancing the ribbon by the correct amount between each strike, and rolling the used ribbon onto the roll of used ribbon. Thus, the invention provides a simple means for ensuring that the ribbon is advanced by the correct amount between each strike and at the same time provides for the necessary rolling of the used ribbon without the use of slipping drive arrangements.

The preferred embodiment of the invention provides a cassette which requires a relatively low and constant drive torque as compared with prior art cassettes and which is of simple and economic construction.

In the preferred embodiment of the invention the periphery of the rotary drive roller is provided with spikes which pierce the used ribbon as it is rolled onto the roll of used ribbon. This arrangement provides a positive driving connection between the drive roller and the used ribbon and thereby prevents any slippage which could result if only friction was relied on to provide the desired advance of the used ribbon. In addition, the spiked drive roller ensures that the used ribbon is rolled tightly onto the roll of used ribbon.

If desired, the spiked drive roller may be of a relatively large diameter and may be connected to the drive spindle of the apparatus by way of a reduction gear housed within the cassette.

In the preferred embodiment of the invention the roll of new ribbon and roll of used ribbon are mounted on mandrels which are slidable in a slot provided in the casing of the cassette. In one embodiment an elastic member secured to the mandrel of the roll of new ribbon biases the mandrel of the roll of new ribbon against a spacer which is supported on the mandrel of the roll of used ribbon and which in turn biases the periphery of the roll of used ribbon against the drive roller. In another embodiment an elastic member secured to the casing of a cassette reacts directly against the mandrel of the roll of used ribbon to bias the periphery of the roll of used ribbon against the drive roller.The elastic member may comprise an elastic band or a strip of elastomeric material secured at one end to the mandrel and passing through a slot formed in an anchor member secured to the casing of the cassette.

The invention will be better understood from the following description of preferred embodiments thereof, given by way of example only, reference being had to the accompanying drawings, wherein: Figure 1 is a schematic view of a first embodiment of the invention; Figure 2 is a schematic view of a second embodiment of the present invention; Figure 3 illustrates a preferred embodiment of drive roller; Figures 4-6 show respectively an exploded view, an elevational view, and a plan view of the drive roller of Figure 3; and Figure 7 is a perspective view illustrating a tensioning arrangement which may be used in the embodiment of Figure 1.

Referring firstly to Figure 1 there is illustrated an arrangement for advancing a film-type printing ribbon 1 from a roll 2 of new ribbon through a printing station 3 to a roll 4 of used ribbon.

Advance of the ribbon is effected by a drive roller 5 which is coupled to a stepping motor to produce a predetermined angular rotation of the drive roller 5 between each successive strike of the character defining member within the printing station 3. The periphery of the drive roller 5 is in non-slipping engagement with the surface of the ribbon 1 so that each angular advance of the drive roller 1 produces a predetermined linear advance of the ribbon through the printing station 3. The zone of engagement of the drive roller 5 with the ribbon 1 is at the point where the ribbon 1 joins the roll 4 of used ribbon, and accordingly each successive rotation of the drive roller 5 winds a portion of used ribbon onto the roll 4 of used ribbon.

The rolls 2, 4 are mounted on respective mandrels 8, 9 which are free to move along a slot 10. The mandrels 8, 9 engage opposite ends of a spacer 6, and the mandrel 8 is engaged by a suitable elastic member, e.g. an elastic band 7 which in turn engages a fixed abutment or anchorage 13. The elastic band 7 is of a size to provide a desired bias to the mandrel 8, thereby maintaining the mandrel 8 in contact with the spacer 6 and applying to the spacer 6 a bias which is transmitted to the mandrel 9 to maintain the roll 4 of used ribbon in contact with the drive roller 5.

As the ribbon passes from the roll 2 to the roll 4 in use, the diameter of the roll 4 increases and the mandrel 9 moves along the slot 10, pushing ahead of it the remainder of the roll 2 by means of the spacer 6.

A suitable tensioning spring arrangement 20 is provided to control unrolling of the roll 2 of new ribbon. The arrangement may comprise a spring having an arm 21 about which the ribbon 1 passes, and an arm 22 which acts against the mandrel 8 as a brake against the free unrolling of the roll 2. When the drive roller 5 rotates the roll 4, the increased ribbon tension moves the arm 21 to the right as viewed in Figure 1, and this in turn causes the arm 22 to release the roll 2, allowing a portion of the roll 2 to unroll and relieve the tension. This in turn allows the arm 21 to move back to the left and re-apply the brake.

In the preferred embodiment of the invention the rolls 2 and 4, drive roller 5, spacer 6, elastic member 7, anchorage 13 and spring 20 are all located within a closed cassette, with only that portion of the ribbon 1 which is located within the printing station 3 being exposed on the exterior of the cassette. Conveniently, the slot 10 is formed in the base of the cassette.

It will be appreciated that the embodiment of the invention described above provides a particularly simple arrangement for advancing a printing ribbon from a roll of new ribbon through a printing station. No slipping drive arrangements are necessary in order to roll the used ribbon onto the roll of used ribbon, and the torque required to rotate the drive roller 5 is low and is substantially constant throughout the transfer of ribbon from the roll 2 to the roll 4. The embodiment described above is particularly suitable for a multi-strike arrangement, i.e. one in which consecutive strikes of the character defining member overlap on the ribbon.The embodiment of Figure 2 is the same as that of Figure 1 except that the spacer 6 has been omitted and the roll 4 of used ribbon is biased into contact with the drive roller 5 by an elastic band 7A which engages the mandrel 9 and two fixed abutments 1 3A. This embodiment is particularly suitable for single strike arrangements, i.e.

arrangements in which each increment of the ribbon is used once only.

If the cassettes described above are to be used in a conventional typewriter or the like the roll 2 of new ribbon must be rolled such that the printing surface of the ribbon is directed radially outwardly.

Referring now to Figures 3-6 the drive roller 5 of the preferred embodiment of the invention is shown in greater detail.

The drive roller comprises upper and lower plastics mouldings 14, 1 5 respectively between which is sandwiched a metal pressing having a plurality of points 17 formed around the circumference thereof. The mouldings 14, 1 5 and pressing 16 are permanently bonded together to form a drive roller in which only the points or spikes 17 of the metal pressing 16 protrude beyond the periphery of the plastics mouldings 14, 1 5. In use, the points 17 pierce the used ribbon 1 over a sector A of the drive roller in order to produce a positive driving engagement between the drive roller and the ribbon 1. The points 1 7 also help to ensure that the ribbon 1 is wound tightly on the roll 4 of used ribbon.

Finally, referring to Figure 7 an alternative arrangement for applying tension to the mandrel 8 of the embodiment of Figure 1 is shown. In this arrangement a strip 11 of elastomeric material is secured to the mandrel 8 and to an anchorage member 12. The anchorage member 12 will be formed integrally with or secured to the casing of the cassette of the preferred embodiment and includes a slot 1 8 through which the elastomeric strip 11 passes. The thickness of the slot is less than the relaxed thickness of the strip 11 and is substantially equal to the thickness of the strip 11 when the strip is tensioned to provide the desired bias on the mandrel 8 of the roll 2 of new ribbon.

Thus, during assembly of the cassette the strip 11 is first secured to the mandrel 8 and is then manually tensioned before being located in the slot 1 8. The free end 19 of the strip is then released permitting the portion of strip located between the free end and the slot 1 8 to assume its unstressed thickness. If the tension in the stressed part of the strip 11 between the slot 1 8 and the mandrel 8 is too great the strip will automatically slide through the slot 1 8 until the tension in the stressed portion of the strip is correct. Similarly, in use if the mandrel 8 moves away from the anchorage 12 by an amount sufficient to increase the tension in the strip 11 by an undesirable amount then fresh strip will automatically pass through the slot 1 8 in order to reduce the tension in the strip 11 to a satisfactory level.

Claims (10)

1. Apparatus including a ribbon which, in use of the apparatus, is wound from a roll of new ribbon through a work station to a roll of used ribbon, the apparatus comprising: a rotary drive roller which is in rolling driving engagement with the periphery of the roll of used ribbon; and means mounting the roll of used ribbon for movement relative to the drive roller to maintain said rolling driving engagement as the diameter of the roll of used ribbon increases in use.

2. Apparatus according to claim 1 wherein the roll of used ribbon is formed on a mandrel which is movable along at least one slot to permit movement of the roll of used ribbon relative to the drive roller, and including resilient means biasing the roll of used ribbon into rolling driving engagement with the drive roller.

3. Apparatus according to claim 2 wherein the roll of new ribbon is mounted on a mandrel which is movable along the at least one slot, and wherein the resilient means comprises a resilient member which acts on the mandrel of the roll of new ribbon to bias the mandrel thereof along the slot and means transferring thrust from the roll of new ribbon to the roll of used ribbon to maintain the roll of used ribbon in rolling driving engagement with the drive roller.

4. Apparatus according to claim 3 wherein the means transferring thrust comprises a spacer located between the mandrels.

5. Apparatus according to claim 2 wherein the resilient means is a resilient member which acts on the mandrel of the roll of used ribbon.

6. Apparatus according to claim 2, 3 or 4 wherein the axes of the drive roller and mandrels are substantially in alignment.

7. Apparatus according to any of claims 2 to 6 wherein the resilient means is an elastomeric member.

8. Apparatus according to any preceding claim wherein the ribbon is a film ribbon and the roll of new ribbon is wound with the printing surface thereof facing outwardly.

9. Apparatus according to any preceding claim wherein the drive roller and the rolls of new and used ribbon are located within a cassette.

10. Apparatus, substantially as hereinbefore described with reference to and as shown in the accompanying drawings.