Toner fusing device with a supply of fusing oil

Abstract

 The invention relates to a device for fusing toner, in particular powder toner, to a printing material (8), said device comprising at least one fusion roller (1), which can be warmed or heated and which contacts the toner for fusing, and comprising at least one working roller (6,7) which is preferably arranged axis-parallel to the fusion roller (1) and in abutting contact with the surface of the fusion roller (1) or which can be brought into abutting contact with the surface of the fusion roller (1).
Therefore, the object of the invention is to further improve a device of the aforementioned type in view of a controlled and/or uniform film of a liquid fusion adjuvant.
In accordance with the invention, this object is achieved in that the working roller (6,7) or at least one working roller (6,7) can be moved in an oscillating manner in its axial direction.

Description

[0001] The invention relates to a device for fusing toner, in particular powder toner, to a printing material, said device comprising at least one fusion roller, which can be warmed or heated for fusing and which contacts the toner, and comprising at least one working roller, which is preferably arranged axis-parallel to the fusion roller and is in abutting contact with the surface of the fusion roller, or which can be brought into abutting contact with the surface of the fusion roller.

[0002] A device of the aforementioned type has been known from EP-A-0 864 941. In addition to the fusion roller, this device comprises metering rollers for the removal of fusing oil from a fusing oil bath, an applicator or donor roller for the application and transfer of the picked-up fusing oil to the fusion roller, a spreading roller for the uniform spreading of the fusing oil on the fusion roller, and a cleaning roller for cleaning the spreading roller. This fusion roller is arranged in an axis-parallel manner with respect to said working rollers.

[0003] Before each fusing operation, a fusing oil film is applied to the fusion roller, so that, after fusing, the heated or melt-deposited toner detaches more easily from the fusion roller and does not adhere to said fusion roller. Adhering toner would contaminate the fusion roller for subsequent fusing operations and, as a result, subsequently fused prints would be negatively affected. However, the fusing oil can also impair subsequently fused prints, in particular for example, create shiny streaks on subsequent printed images if said fusing oil is applied in too large an amount, or not uniformly, to the fusion roller. In the worst case, the entire transport path used by the printing material could be contaminated by fusing oil and, in particular, also damage verso prints.

[0004] Therefore, the object of the invention is to further improve a device of the aforementioned type in view of a controlled and/or uniform film of a liquid fusion adjuvant.

[0005] In accordance with the invention, this object is achieved in that the working roller, or at least one working roller, can be moved in an oscillating manner in its axial direction.

[0006] The axial motion ensures a uniform and controlled film by spreading and/or eliminating said film.

[0007] Preferably, the working roller can be driven in an oscillating manner, in which case appropriately suitable drives are known per se from other contexts, for example, from ink friction wheels used in the rotary press printing machines of DE-A-42 31 260.

[0008] The axially movable working roller may be any of the aforementioned rollers, in particular also a cleaning roller; however, a development of the invention preferably provides that the working roller is a spreading roller or a friction roller for spreading a liquid fusion adjuvant, specifically a fusing oil. As a result of this, in accordance with the invention, the film is spread and controlled particularly well on the fusion roller in order to specifically avoid streaking.

[0009] Preferably, the spreading roller is in contact with an axis-parallel donor roller, which, in turn, applies or transfers the fusion adjuvant to the fusion roller. In so doing, the film is adjusted in a uniform and controlled manner even before its transfer to the fusion roller. To achieve this, the spreading roller could be arranged in an axis-parallel manner between the donor roller and a removal or metering roller that acts as transfer member and removes the fusion adjuvant from a reservoir, however, the spreading roller is preferably arranged next to the metering roller in order to avoid a longer transfer link chain which, due to friction losses, could impair the rotation of all the rollers. Therefore, preferably, the spreading roller, which can be moved in axial direction in accordance with the invention, is intended to be only in linear abutment, this being achieved by making the surface of the spreading roller of a hard and largely inelastic material. In addition, the surface of the spreading roller may be smoothed, or more particularly, polished.

[0010] One embodiment of an inventive device is shown in the drawing by a single figure, depicted schematically and basically only in side elevation or in a sectional view.

[0011] The figure shows a fusion roller 1, which can be driven by means of a rotation generator 2 to rotate in the direction of the arrow. Fusion roller 1 is used to fuse a printing image to a printing material 8; to achieve this, said fusion roller can be heated in order to melt-deposit a preferably powder-shaped toner that forms the printed image on a printing material 8 and to incorporate said toner in said printing material. To achieve this, fusion roller 1 works together with an impression cylinder 9, which is only suggested in the drawing.

[0012] To prevent the toner after the fusing step from adhering to fusion roller 1, a film of a fusing oil is first applied in a uniformly spread manner to the fusion roller, namely to the generated surface of fusion roller 1. This is done with a donor roller 6 that rotates in a direction opposite to fusion roller 1, said donor roller, in turn, receiving the fusing oil from a metering roller 4, which removes the fusing oil from a fusing oil reservoir 3. To do so, metering roller 4 is immersed below fluid level 10 of a fusing bath. The thusly removed fusing oil is first spread and squegeed by means of a squegee 5 to form a film on metering roller 4 before said film is transferred to donor roller 6.

[0013] In addition, a friction roller 7 abuts against donor roller 6, said friction roller being drivable in accordance with the invention in such a manner that it oscillates in its axial direction and, at the same time, being rotatable in the direction opposite donor roller 6, so that the fusing oil film on donor roller 6 is spread even more uniformly in a controlled manner. Alternatively, friction roller 7 could be provided as an intermediate member between donor roller 7 and metering roller 4.

Claims

1. Device for fusing toner, in particular powder toner, to a printing material, said device comprising at least one fusion roller, which can be warmed or heated and which contacts the toner for fusing, and comprising at least one working roller which is arranged preferably axis-parallel to the fusion roller and in abutting contact with the surface of the fusion roller, or which can be brought into abutting contact with said fusion roller,
characterized in that
the working roller can be moved in an oscillating manner in its axial direction.

2. Device as in Claim 1, characterized in that the working roller can be driven in an oscillating manner.

3. Device as in Claim 1 or 2, characterized in that the working roller is a spreading roller or friction roller for spreading a liquid fusion adjuvant, in particular, a fusing oil.

4. Device as in Claim 3, characterized in that the spreading roller contacts an axis-parallel donor roller, which, in turn, applies or transfers the fusion adjuvant to the fusion roller.

5. Device as in Claim 4, characterized in that the spreading roller is arranged in an axis-parallel manner between the donor roller and a removal roller or metering roller, which removes a fusion adjuvant from a reservoir and is arranged as a transfer member for the fusion adjuvant.

6. Device as in one of the Claims 3 through 5, characterized in that the surface of the spreading roller is made of a hard and largely inelastic material.

7. Device as in Claim 6, characterized in that the surface of the spreading roller has been smoothed.

Drawing