GB2140387A - Ribbon cassette - Google Patents

Abstract

The cassette is for holding a continuous ribbon for use in a computer and has an opening (26) through which the ribbon is fed. The cassette has a two-part housing comprising a base (11) and a lid (12). The base is a plastics moulding having integrally formed arms (40, 41) formed with rebates (42, 43) at their free ends. A pair of meshed gears (13, 14) receive the ribbon for feeding the latter and each gear has a peripheral groove (50) defining a hub which is rotatably received in a corresponding rebate (42, 43). One arm (41) is carried by a resilient tongue (45) biasing the gears into mesh and being movable to permit insertion of the gears. <IMAGE>

Description

SPECIFICATION Ribbon cassette This invention relates to a ribbon cassette of the type intended for holding a continuous ribbon and adapted for feeding the ribbon past an opening. Such ribbon cassettes are used, for example, for computers.

The invention provides a cassette which has a particularly simple construction and which is capable of rapid assembly.

In accordance with this invention, a ribbon cassette comprises a housing including a base having shallow side walls, and a lid engageable with the base, an opening being defined in the side walls for displaying, in use, a portion of a continuous ribbon accommodated in the housing, a storage region in the housing, drive means for moving the ribbon, and guide means for guiding the driven ribbon past the opening, the drive means including first and second gears mounted in the housing for engaging the ribbon, each gear having a peripheral groove, the housing being provided internally with arms having rebates for engaging with the grooved parts of the gears so as rotatably to support the gears and hold them in mesh, one of said arms being movable to permit insertion of a gear followed by movement of the gear into the meshing position.

Preferably, the movable arm is resiliently biased into the position in which the gears mesh. The arms are preferably intergral parts of a one-piece plastics moulding forming the base and the resilience is inherent in the arm or the part of the base to which the arm is attached. It is also preferred that the arm is resiliently movable in a direction lying in a plane traverse to the axes of rotation of the gears.

Reference is now made to the accompanying drawings, wherein: Fig. 1 is a perspective view of a base portion of a cassette according to the invention, showing ribbon drive gears mounted in operative positions; Figure 2 is a plan view of the cassette with a lid attached and parts broken away to show the interior; and Figure 3 is a front elevation of the cassette without the gears in position and with a part of the lid broken away.

The cassette shown comprises four moulded parts consisting of a base, 11, a lid 12 and two gears 13, 14.

The base 11 and the lid 12 together define a housing and the base has a bottom panel 20 provided with shallow side walls 21. The base has apertures such as 22 and spigots such as 23. The lid 12 has a top panel 30 provided with apertures and spigots, such as 32, which engage with corresponding spigots and apertures respectively of the base to secure the lid on the base.

In the particular cassette illustrated, the housing is generally of U-form with the outer surface of the U defined by the side walls 21 to leave an opening 26 in the side walls at the mouth of the U. The inner surface of the U is defined by wall 27. The walls 27 diverge from the opening 26.

One limb of the U has a broader interior than the other limb and defines a ribbon storage region 28. A continuous path for the ribbon is defined around the walls 27 and past the opening 26, with integral guide pins and ledges, such as 29 serving to guide the ribbon. The ribbon is housed in the storage region 28 in convoluted form.

The gears 13, 14 are mounted in the housing in mesh and the ribbon path passes between the gears. In use, at least one of the gears is driven to move the ribbon around the path and past the opening 26.

For mounting tthe gears, the walls 27 have a short perpendicularly projecting arm 40 and the side walls have a longer perpendicularly projecting arm 41. The free end of each arm has a generally part-circular rebate 42, 43.

The arms are integral parts of the plastics moulding defining the base.

The shorter arm is rigidly fixed against movement parallel to the panels 20, 30, i.e.

in a plane perpendicular to the axes of the gears, and rigidity is reinforced by a rib 44 joining the arm to the walls 27.

The longer arm is carried by a lug 45, which permits resilient movement of the longer arm in said plane, perpendicular to the axes of the gears. The lug is an integral part of the side walls 21 and is defined by a slot 46 separating the lug from the bottom panel 20. The longer arm is resiliently biased to a predetermined, as-moulded, position. The lug 45 is integral with a block 48 formed with one of the apertures 22.

Each gear 13, 14 has a peripheral groove 50 defining a hub spacing two gear portions 13a, 13band 14a, 14b. The hubs are received in respective rebates 42, 43 in the arms, the arms defining bearings rotatably locating the gears in mesh.

The longer arm 41 is moved from its normal position to permit insertion of the gears in the respective rebates. On release the gear 14 is resiliently biased into mesh with the other gear 13. Once the lid 12 is mounted on the base 11 the lug 45 is held against movement by one of spigots (not shown) on the lid 12 engaging in the aperture 22 in the block 48.

At least one of the gears 13 has an aperture (not shown) which aligns with an aperture 55 in the bottom panel 20 to receive a drive spindle. This gear 13 also has a boss 56, which permits manual turning of the gear, and projects through an aperture in the top panel 30.

The gears can be very easily and quickly mounted in position and are firmly held in place in the base 11, so that fitting of the lid 12 is not inhibited.

It is possible for two cassettes to be superimposed in a composite cassette assembly with gears of each cassette being integrally formed with corresponding gears of the other cassette.

Claims (6)

1. A ribbon cassette comprising a housing including a base having shallow side walls, and a lid engageable with the base, an opening being defined in the side walls for displaying, in use, a portion of a continuous ribbon accommodated in the housing, a storage region in the housing, drive means for moving the ribbon, and guide means for guiding the driven ribbon past the opening, the drive means including first and second gears mounted in the housing for engaging the ribbon, each gear having a peripheral groove, the housing being provided internally with arms having rebates for engaging with the grooved parts of the gears so as rotatably to support the gears and hold them in mesh, one of said arms being movable to permit insertion of a gear followed by movement of the gear into the meshing position.

2. A ribbon cassette according to Claim 1, wherein the movable arm is resiliently biased into the position in which the gears mesh.

3. A ribbon cassette according to Claim 2, wherein the movable arm is movable in a direction lying in a plane transverse to the axes of rotation of the gears.

4. A ribbon cassette according to Claim 2 or 3, in which the arms are integral parts of a one-piece plastics moulding forming the base and the resilience is inherent in the arm or the part of the base to which the arm is attached.

5. A ribbon cassette according to Claim 4, wherein the base has a side wall provided with a slot so as to define a tongue, the movable arm being carried by the tongue and the tongue providing for resilient movement of the movable arm.

6. A ribbon cassette constructed substantially as herein described with reference to the accompanying drawings.