GB2104623A

GB2104623A - Transport roller for a record carrier in a printer

Info

Publication number: GB2104623A
Application number: GB08217100A
Authority: GB
Inventors: Franz Mucha; Gerhard Habelt
Original assignee: Philips Gloeilampenfabrieken NV
Current assignee: Koninklijke Philips NV
Priority date: 1981-06-15
Filing date: 1982-06-11
Publication date: 1983-03-09
Also published as: FR2507544B1; SE440885B; DE3221774A1; IT8221813A0; FR2507544A1; IT1154008B; AT381387B; JPS5816876A; ATA266981A; JPH0156915B2; GB2104623B; SE8203631L; CA1190799A

Abstract

A transport roller for a record carrier in a printer, for example, an ink jet printer, is composed of at least two laterally adjoining, hollow, cylindrical roller sections (1). Each roller section is connected to a hub (5) by means of at least one carrier (4). The roller sections are adjacently arranged on a shaft (7) by way of the hub so that they am locked against rotation. An axial clamping device (10, 11, 12) ensures that the roller sections are pressed against one another. Furthermore, at a first lateral end (13) of each roller section there is provided a groove (8) which opens towards this first end and in which there is arranged an O-ring (9). The laterally open groove is closed by the roller section which adjoins this first lateral end. The roller end sections (2 and 3) may be constructed as so-called spiked rollers for the transport of a record carrier comprising a perforated edge. <IMAGE>

Description

SPECIFICATION Transport roller for a record carrier in a printer The invention relates to a transport roller for a record carrier in a printer, said transport roller comprising toroidal rings which are adjacent arranged at a distance from one another in the longitudinal direction of the roller, each of said rings being arranged in a groove on the circumference, the record carrier being guided by said rings. The toroidal rings are also referred to as O-rings. The rolling body of such a transport roller in commercially available printers consists of one piece.It is a problem that the grooves for the toroidal rings (which must be proportioned comparatively accurately) must be subjected to a special treatment, because all toroidal rings must occupy exactly the same position with respect to the circumferential surface of the roller body in order to ensure that the path of the record carrier around the transport roller is uniformly cylindrical across the entire length of the roller. It is only then ensured that the path of the record carrier behind the transport roller is regular and exactly defined.

This is important, for example, when after departure from the transport roller, the record carrier is fed to a flat supporting surface along which a printing head of a printer is guided to be displaceable in Ijie line direction; in such a case the record carrier must rest flatly on the supporting surface in order to ensure that the distance between the printing head and the record carrier remains constant. This requirement must be satisfied, for example, in the case of ink jet printing heads.

It is an object of the invention to construct a transport roller of the kind set forth so that it can be simply and cheaply manufactured, notably in bulk, without special treatments being required, whilst the path of the record carrier around the transport roller is still regular and exactly defined.

To this end, the transport roller in accordance with the invention is characterized in that it comprises at least two laterally adjoining, mainly hollow, cylindrical roller sections, a hub being connected to each roller section via at least one carrier, the roller sections being adjacently arranged on a shaft by way of their hubs so that they are locked against rotation and are pressed against one another by means of a clamping device, each roller section comprising one of the grooves which is provided at a first lateral end of the roller section and which is open towards this first lateral end, the roller section adjoining this first lateral end closing the open side of the groove by way of its second lateral end.Because the transport roller is composed of several roller sections, the individual roller sections are shorter accordingly, so that each section can be simply manufactured with high precision. For example, the separate roller sections can be very cheaply and simply made of plastics by injection moulding. Furthermore, the mounting of the toroidal rings is very simple, because they can be readily arranged in the laterally open groove of each roller section.

For the construction and arrangement of the hub and the carrier connecting the hub to the hollow cylindrical roller section a series of possibiiities exist within the range of the customarily used techniques. For example, for the accurate and stable journalling of a roller section on the shaft, use can be made of a hub which extends approximately over the full length of the roller section and which is connected to the hollow cylindrical roller section via a partition-like transverse wall which acts as a carrier.A preferred embodiment of the transport roller in accordance with the invention is characterized in that the hub of a roller section is arranged near the second lateral end, the hub projecting beyond this second lateral end, viewed in the axial direction, the carrier for the hub being connected to the roller section near the first lateral end and enclosing a coaxial recess for accommodating the hub of the roller section adjoining this first lateral end, the internal dimension of said coaxial recess corresponding to the external dimension of the hub. Each hub can thus be constructed to be comparatively short; accurate journalling of each roller section, however, is still obtained because the hub of one roller section serves also as a journal for the second roller when two roller sections are arranged one behind the other; thus, each roller section is actually journalled twice.

Because a bearing for the roller section is situated near each toroidal ring, it is ensured that the toroidal rings are very exactly positioned. It is a further advantage that the precision manufacture of shorter hubs is easier.

The carrier which connects the hub to the roller section may be constructed, for example, as a solid body. In view of a simple but stable construction and ease of manufacturing, the hub is preferably connected to the roller section by way of at least three spoke-like carriers.

The invention will be described in detail hereinafter with reference to the drawing which shows an embodiment in accordance with the invention.

Fig. 1 is a longitudinal sectional view of a transport roller consisting of several roller sections, Fig. 2 is a longitudinal sectional view at an increased scale of a single roller section of the transport roller shown in Fig. 1, and Fig. 3 is a cross-sectional view of the roller section shown in Fig. 2.

The transport roller shown in Fig. 1 consists of five identical, hollow, cylindrical roller sections 1 and two roller end sections 2 and 3. The construction of the roller end section 2 is quite similar to that of the roller sections 1. The roller sections 1 and the roller end section 2 are each connected to a hub 5 via carriers 4. The roller end section 3 also comprises a hub 6. The roller sections 1 and the roller end sections 2 and 3 are adjacently arranged on a shaft 7 by way of the hubs 5 and 6 so that they are locked against rotation, the roller end sections 2 and 3 constituting the lateral ends of the transport roller.

All roller sections are locked against rotation, for example, in that the shaft 7 consists of a profiled rod on which the correspondingly shaped hubs of the roller sections are fitted. Between each pair of laterally adjacent roller sections 1 and also between the roller end sections 2 and 3 and the adjacent roller sections 1 there is provided a toroidal ring 9 which is arranged in a groove 8 at the circumference of the roller sections 1 and the roller end section 2.The roller sections 1 and the roller end sections 2, 3 are clamped together by means of an axial clamping device which comprises two discs 10 and 11 which are arranged on the shaft 7 at an axial distance from one another and an intermediate spring 12 which bears on the one side against the disc 10 and on the other side against the roller end section 3, the hub 5 of the roller end section 2 bearing against the disc 11. The roller sections 1 and the roller end sections 2 and 3 are thus pressed against one another by way of their lateral ends. The transport roller thus constitutes one structural unit which can be rotatably journalled, for example, in a printer by way of the free ends of the shaft 7. Such a transport roller then serves, for example, for the continuous or intermittent feeding of a sheet-like record carrier.The record carrier can then also be pressed by means of pressure rollers which co-operate with the toroidal rings in order to ensure correct transport. The roller end sections 2 and 3 may also be constructed as so-called spiked rollers for the transport of a record carrier comprising a perforated edge.

The Figs. 2 and 3 show a roller section 1 with the hub 5 which is connected thereto via the carrier 4 in greater detail. It is clearly shown that each roller section 1 comprises, at a first lateral end 13 (the left end in Fig. 2), a groove 8 which opens towards the first lateral end 1 3 and which is closed by the second lateral end 14, situated opposite the first lateral end 13, of an adjacently situated roller section, so that a toroidal ring arranged in the groove 8 is suitably positioned.

In the described embodiment, the hub 5 of a roller section 1 is situated near the second lateral end 14 and projects beyond this second lateral end, viewed in the axial direction. The hub 5 is connected to the roller section 1 by way of six spoke-like carriers 4. The carriers 4 are connected to the roller section 1 near the first lateral end 13.

Near this first lateral end the carriers enclose a coaxial recess 1 5 whose internal dimension corresponds to the external dimension of the hub 5. The recess 1 5 serves to accommodate the hub 5 of the next roller section which adjoins the first lateral end 13, the part of the hub 5 which projects beyond the second lateral end 1 4 of the next roller section then being situated in the recess 1 5. Near the first end 1 3 the carriers 4 thus bear on the hub 5 of the adjacent roller section 1, so that double a bearing is obtained for each roller section, that is to say on the one hand via its own hub 5 and on the other hand via the hub 5 of the adjacent roller section.The same is applicable to the roller end section 2 and the roller section 1 adjoining the roller end section 3, because the hub 6 of the roller end section 3 engages in the recess 1 5 thereof. Because all bearings are effective near the first end 1 3 with the groove 8 of each roller section, a suitable support is obtained near the grooves 8 for all roller sections, so that the position of the toroidal rings 9 arranged in the grooves 8 is accurately defined. A very exact and uniform path of the record carrier around the transport roller is thus obtained; this is particularly important, for example, when the record carrier is fed from the transport roller to a flat supporting surface along which a printing head of a printer is displaced, for example, an ink jet printing head which co-operates with the record carrier.

In the described embodiment, the continuous hub opening 1 6 provided in each hub 5 is hexagonal in order to prevent rotation of the roller sections on the shaft 7 which has a corresponding cross-section. Evidently, other corresponding cross-sections could also be chosen for this purpose, for example, a rectangular cross-section etc. As appears notably from Fig. 2, the hollow cylindrical interior of the roller section 1 and the exterior of the carriers 4 and the hub 5 have a slightly conical shape, so that these parts can be very simply manufactured by means of the injection moulding technique. The material used is, for example, a synthetic material so that the manufacture can be simple, accurate and cheap.

Because the transport roller is composed of several short roller sections, each of which is accurately manufactured, all roller sections being accurately journalled at the area of the toroidal rings, the positions of the toroidal rings are accurately defined, so that the sites for the toroidal rings (formed by the grooves) need not be further treated. Consequently, such a transport roller can be very simply and cheaply manufactured, whilst it still offers suitable transport of the record carrier as well as a regular path thereof around the transport roller.

Obviously, a series of modifications are feasible within the scope of the invention. This is notably applicable to the arrangement and the construction of the hubs and the carriers connecting the hubs to the hollow cylindrical roller sections. In this respect it is to be noted that at the areas where the roller sections laterally adjoin one another, mutually engaging fits or supports may be provided.

Claims

1. A transport roller for a record carrier in a printer, said transport roller comprising toroidal rings which are adjacently arranged at a distance from one another in the longitudinal direction of the roller, each of said rings being arranged in a groove on the circumference, the record carrier being guided by said rings, characterized in that the transport roller comprises at least two laterally adjoining, mainly hollow, cylindrical roller sections, a hub being connected to each roller section via at least one carrier, the roller sections being adjacently arranged on a shaft by way of their hubs so that they are locked against rotation and are pressed against one another by means of a clamping device, each roller section comprising one of the grooves which is provided at a first lateral end of the roller section and which is open toward this first lateral end, the roller section adjoining this first lateral end closing the open side of the groove by way of its second lateral end.

2. A transport roller as claimed in Claim 1, characterized In that the hub of a roller section is arranged near the second lateral end, the hub projecting beyond this second lateral end, viewed in the axial direction, the carrier for the hub being connected to the roller section near the first lateral end and enclosing a coaxial recess for accommodating the hub of the roller section adjoining this first lateral end, the internal dimension of said coaxial recess corresponding to the external dimension of the hub.

3. A transport roller as claimed in Claim 1 or 2, characterized in that the hub is connected to the roller section by way of at least three spoke-like carriers.

4. A transport roller substantially as herein described with reference to the accompanying drawings.