DRIVING FORCE COUPLING AND A PRINTER CARTRIDGE INCLUDING COUPLING

FIELD OF THE INVENTION

The invention relates to a dπviπg force member. The driving force member is particularly suited to receive a rotational driving force transferred by way of an additional driving force member taking the form of either a twisted or non-twisted recess.

BACKGROUND TO THE INVENTION

The following discussion of the background of the invention is intended to facilitate an understanding of the present invention. However, it should be appreciated that the discussion is not an acknowledgment or admission that any of the material referred to was published, known or part of the common general knowledge in any jurisdiction as at the priority date of the application.

Driving force members are commonly used in any situation where a rotational driving force needs to be transferred from one article to components of another article. Typically, the two driving force members are configured such that the internal profile of one is matched to the external profile of the other. This match in profiles is often an identical match.

Recently, in the field of process and developer cartridges, driving force members included to transfer substantially coaxial rotational driving force from an image processing apparatus to the photosensitive drum, or like components, have been implemented in the form of a twisted projection to be received within a twisted recess. While the use of driving force members having twisted profiles have produced benefits in the form of the driving force member being self-centring and also assisting in preventing disengagement of the driving force members while a rotational driving force is being applied, it has also introduced further complications. For instance:

• Existing driving force members not having a twisted profile can not be used with a driving force member having a twisted profile because the

point of engagement between the two driving force members is insufficient to facilitate the transfer of the rotational driving force;

• A driving force member having a twisted profile requires further precision tooling equipment such as plastic injection moulding machinery, to meet the exacting tolerances the twisted profile sets, and

• A driving force member having a twisted profile is prone to breakage or deformation along its length by reason of its twisted profile. When breakage occurs, the failed components have significant rotational driving force applied to them and thus often cause damage to other components near the driving force members.

• A driving force member in the form of a projection capable of engaging with a recess must be substantially as long as the recess is deep to enable full engagement.

It is therefore an object of the present invention to create a driving force member that seeks to provide at least one of the advantages of a driving force member having a twisted profile while overcoming at least one of the disadvantages of a driving force member having a twisted profile and that can be used with driving force members having either a twisted recess or non-twisted recess profile.

It should be appreciated that while the following description will be made in relation to image processing equipment, it is not restricted to use and may be used in any circumstance where rotational driving force is required to be imparted from one component to another.

SUMMARY OF THE INVENTION .

Throughout this document, unless otherwise indicated to the contrary, the terms "comprising", "consisting of, and the like, are to be construed as non-exhaustive, or in other words, as meaning "including, but not limited to".

In accordance with a first aspect of the invention there is a first driving force member having an external profile adapted to engage a second driving force

member of substantially similar size having either a twisted or non-twisted recess such that, when so engaged, rotational driving force can be transferred from one driving force member to the other, the external profile of the first driving force member contacting the rim of the second driving force member along at least one line contact portion.

Preferably, the first driving force member further comprises three side portions. More preferably the side portions each further comprise a line contact portion.

Preferably each side portion of the first driving force member extends outwardly from the first driving force member.

More preferably the first driving force member is tapered in a longitudinal direction thereof.

Preferably the first driving force member has an electroconductive component.

In accordance with a second aspect of the present invention there Is a printer cartridge for use in a xerographic printer comprising a first driving force member having an external profile adapted to engage a second driving force member of substantially similar size having either a twisted or non-twisted recess such that, when so engaged, rotational driving force can be transferred from one driving force member to the other, the external profile of the first driving force member contacting the rim of the second driving force member along at least one line contact portion.

Preferably, the first driving force member of the printer cartridge further comprises three side portions. More preferably the side portions each further comprise a line contact portion.

Preferably each side portion of the first driving force member of the printer cartridge extends outwardly from the first driving force member.

More preferably the first driving force member of the printer cartridge is tapered in a longitudinal direction thereof.

Preferably the first driving force member of the printer cartridge has an electrocoπductive component.

More preferably the first driving force member of the printer cartridge is attached to a rotatable member.

Preferably the rotatable member is a photosensitive drum. More preferably the rotatable member is a developer roller. More preferably the rotatable member is a charge roller.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a perspective view of a driving force member according to a first embodiment of the present invention,

Figure 2 is a top perspective view of the driving force member shown in Figure 1.

Figure 3 is a perspective view of the driving force member shown in Figure 1 in engagement with a twisted recess.

Figure 4 is a perspective view of a printer cartridge containing the driving force member shown in Figure 1.

PREFERRED EMBODIMENTS OF THE INVENTION

In accordance with a first embodiment of the invention there is a first driving force member 10. The first driving force member 10 comprises a projection 12 and a base 14. The projection 12 is attached to the base 14 such that it has a larger diameter than the base 14 and three side portions 16a, 16b and 16c are exposed.

The three side portions 16a, 16b and 16c extend perpendicularly outwardly from the projection near the base 14 and then taper slightly inwardly as they extend in the longitudinal direction A along the projection 12. Where the side portions 16a,

16b and 16c extend from the projection 12 near the base 14, line contact portions 18a, 18b and 18c are defined for engagement with a second driving force member in the form of twisted recess 60 or non-twisted recess (not shown).

As the driving force member 10 is symmetrical along all three faces, only the side portion 16a and line contact portion 18a are clearly shown. It should be understood that the other two faces comprising side portions 16b and 16c and subsequently line contact portions 18b and 18c, are essentially identical to the shown face of the driving force member 10.

A typical configuration of a twisted recess 60 or non-twisted recess which may be suitable for engagement with a first driving force member 10 may be seen in Figure 3 and consists of the following: an opening 62, a rim 64, inner surfaces 66 (twisted or non-twisted) and a bottom wall 68.

The engagement between the recess 60 and the first driving force member 10 will be described with reference to figure 3. The projection 12 of the first driving force member 10 enters the recess 60 through the opening 62. It is preferred that the projection 12 does not fully enter the recess 60 such that contact is made with the bottom wall 68, rather a gap should be left between the bottom wall 68 of the recess 60 and the projection 12. Once the projection 12 has fully entered the recess 60, the line contact portions 18a, 18b and 18c engage with the rim 64 of the recess 60. The engagement between the recess 60 and first driving force member 10 is thus achieved through contact between the line contact portions 18a, 18b, 18c and the rim 64 of the recess 60.

Once the projection 12 has entered the recess 60 such that the line contact portions 18a, 18b and 18c are engaged with the rim 64 of the recess 60, the recess 60 may be rotated by a rotating member such as a motor (not shown). Driving force will thus be transmitted from the rotating recess 60 to the first

driving force member 10 through the engagement between the line contact portions 18a, 18b, 18c and the rim 64 of the recess 60.

As the first driving force receiving member 10 only contacts the recess 60 at the rim 64, not at any inner surface 66 the driving force receiving member 10 may be of any shape desired, allowing specifically for a simple shape which is easy to manufacture, for example by plastic injection moulding.

The first driving force member 10 may be coaxially connected to a rotatable member such as a photosensitive drum (not shown) by the shaft 14. In this manner, when the projection 12 receives a rotational driving force from the recess 60, the force can be transferred from the projection 12, to the photosensitive drum by the shaft 14, thus enacting rotation of the photosensitive drum.

A potential use for a first driving force member 10 according to a first embodiment of the present invention is in a printer cartridge 50 as shown in Figure 4. The first driving force member 10 is provided at one longitudinal end of the printer cartridge 50. The printer cartridge 50 typically comprises a storage area for toner such as a toner hopper 52 and a storage area for waste toner such as a scavenger unit 54. A typical printer cartridge 50 will comprise at least one rotatable member such as a photosensitive drum 56 or developer roller (not shown). The first driving force member 10 may be attached to one longitudinal end of a rotatable member so as to transmit a rotational driving force serving to rotate the rotatable member, the manner by which the rotational driving force is received and transmitted being that which has been previously described. In the typical printer cartridge 50 shown in Figure 4, the first driving force member 10 is attached to a photosensitive drum 56, however it should be understood that the first driving force member 10 may be used to rotate any member within a printer cartridge 50 which requires rotation.

It should be appreciated by the person skilled in the art that the above invention is not limited to the embodiment described. In particular, the following modifications and improvements may be made without departing from the scope of the present invention ¹

• The profile of the three side portions may differ substantially from that described, and still provide line contact portions for engagement with the rim of a hole.

• More or less than three line contact portions may be provided on the projection.

• The first driving force member 10 may include an electroconductive portion or be formed completely from an electrically conductive material. This allows the first driving force member to ground electrical components to which it is connected

• Although described with reference to the projection 12 acting to receive a driving force, it is also possible that the projection 12 may transmit driving force.

• The first driving force member 10 may be attached to any member requiring rotation, including but not limited to, a developer roller or charge roller.

• The recess 60 may take any configuration that allows the rim 64 to engage with at least one line contact portion on the projection 12.

• The side portions 16a, 16b and 16c may take any configuration including a taper in the opposite direction to that described above.

It should be further appreciated by the person skilled in the art that the features described in one embodiment, where not mutually exclusive or alternatives, may be combined with features described in other embodiments described to create yet further embodiments that fall within the scope of the present invention.