EP0876638B1 - Device for applying release agent to the surface of a fixing roller of an electrographic printer or copier - Google Patents

Description

Release agent application device for applying release agent on the surface of a fixing roller of an electrographic Printing or copying machine

The invention relates to a release agent application device. The release agent application device carries on the surface a fusing roller one working on the transfer printing principle electrographic printer or copier separating liquid on.

In electrographic printing or copying machines, charge images are used on an intermediate carrier, e.g. a photoconductor drum generated, which is then due to electrostatic or magnetic forces with a developer mixture of a developer station be colored. The colored charge images are transferred to a recording medium in a transfer printing station reprinted in the form of single sheets or continuous paper and then thermally fixed. For thermal Fixation is known from US-A-33 24 791, a fixing station to be used with two rollers, between which the carrier of the Toner image is moved through. The one facing the toner image Fuser roller is heated, the other presses the carrier with the toner image against the fuser roller. Through warmth and Pressure is then melted down the toner.

To prevent toner from appearing on the surface of the fuser roller gets stuck, its surface is covered with separating liquid, e.g. Wet silicone oil. To apply this separation liquid on the fixing roller is a release agent application device from DE-C-39 42 147 known in which a felt Application element from one along the fuser roller extending pressure body pressed against the fixing roller becomes. On the side of the application element facing away from the fixing roller a metering tube is provided, which in its Includes longitudinal openings. In the dosing tube pumped release agent emerges from the openings and reaches the application element.

To wetting the surface of the fuser roller of the width To be able to adapt a record carrier is in the metering tube a rotatable control wedge included. Depending on the position This control wedge can have more or less outlet openings be closed, which only on the with the record carrier contacting area of the fixing roller Release agent is released. The location of the control wedge will with a servomotor always in the printer or copier developed recording medium width adapted.

It has now been shown that the adjustment of the oiling width must be done very precisely. If too much release agent from the Release agent metering tube released, then it comes to contamination in the fuser and neighboring units of the Printing or copying machine. If there is too little release agent the surface of the fuser roller, then print image disturbances occur. A satisfactory printing result can therefore can only be achieved if the width of the release agent application works reliably.

However, the release agent application device is due to its direct contact and the heated fuser roller high Exposed to temperatures. These high temperatures lead to a special load on the motor to adjust the Control wedge in the metering tube. This servomotor therefore fails often its service.

It is also from DE-A1-3941195 a release agent application device for applying release agent to the surface a fixing roller of an electrographic printing or Copier known, the one along the fusing roller extending pressure body and a guide elements of the Has pressing element applied application element, about which

Release agent is applied to the fixing roller. For feeding of the release agent to the application element is parallel to the axis a cannula is provided for the fixing roller, which is made of porous textile fiber material can exist.

The present invention has for its object a Release agent application device for applying release agent on the surface of a fixing roller of an electrographic Show printer or copier, even with large thermal stress reliable oiling of the fusing roller without disturbing the printed image and without contamination the fuser and neighboring units of the printing or copier guaranteed.

This object is achieved by the specified in claim 1 Features resolved. Developments and refinements of the invention are specified in subclaims.

The solution according to the invention is more thermal even when it is large Reliable oiling of the fuser roller without disturbing the printed image and without soiling the fuser and neighboring aggregates of the photocopier guaranteed. The solution focuses entirely on adjustment mechanisms waived. Through the interaction of gutter and wick there is always the required amount along the fusing roller Release agents available. The gutter contains a certain one Amount of liquid in the gutter due to the Gravity evenly distributed. The release agent can Channel continuously or at intervals on one side fed and removed on the other side. Preferably however, the channel is closed at its ends.

The wick dips into the gutter, over. their entire longitudinal extent on. The wick takes the release agent out of the gutter by capillary action. This capillary action ensures that in areas where a large amount of release agent from A wick is given to the application element, a corresponding one Amount of release agent is sucked up by the wick. A good Capillary action and absorbency is reduced when using PTFE, polyamide, polyimide and combinations of these Fabrics reached. Because of the good absorbency the wick also serves as a release agent storage. On Because of these storage effects, fluctuating release agent requirements can occur be reacted to. It also affects an uneven The release agent is not fed to the wick Quality of the release agent application on the fusing roller.

According to a development and embodiment of the invention the release agent is fed directly to the wick. To a release agent metering tube extends along the wick across the usable width of the fuser roller. From outlet openings this release agent metering tube becomes release agent Wick given. Excess release agent gets from the wick into the gutter. This causes an accelerated absorption of the Release agent through the wick. A distance is preferred between the release agent metering tube and the wick through a elastic lip bridged. This is liquid-tight with coupled to the release agent metering tube and towards the gutter inclined. This lip ensures that everything from the Release agent escaping release agent directed to the wick becomes. The outlet openings are accordingly above the Coupling area between release agent metering tube and lip arranged.

According to a further development and embodiment of the invention the gutter is part of the lower guide element. The upper guide element contains an undercut Longitudinal groove in which a thickened long side of the wick is retractable. This allows the wick to come in from one side the longitudinal groove of the upper guide element are retracted. The undercut of this longitudinal groove ensures a safe one Hold the wick in the upper guide element. Because the wick dips into the gutter on one side and on the opposite Side is in the longitudinal groove, connects he the lower and the upper guide element with each other.

According to a further development and embodiment of the invention contains the channel sealed on both sides in its Longitudinal walls of different heights. The lower wall is against the application element, so that excess Release agent is given to the application element. If the release liquid level exceeds the low level Wall, it flows in the direction of the application element and is picked up by this and transported away. So that is a defined overflow exists that does not lead to contamination the fuser and adjacent functional element the printer or copier by dripping the Release agent can result.

According to a further development and embodiment of the invention the pressure body is spring loaded. Through this Suspension is a tolerance compensation of the rotating and fixing roller exposed to thermal loads to the release agent application device guaranteed. Precise adjustment work omitted due to the spring of the pressure body towards the fuser roller.

According to a further development and embodiment of the invention serves as a request element a fleece with a thickness between 0.2 to 0.3 mm. This fleece is much thinner than conventional fleeces. Is preferably used as a nonwoven material Polyamide, polyimide and Teflon or combinations thereof are used. A longer length can be achieved by means of the thin fleece of the fleece can be wound up in a small space. With unchanged Maintenance intervals is due to the increased fleece length an increased fleece speed can be realized. This is ensures a higher quality of cleaning the fuser roller, because the fleece is not blocked by dirt can be. The thin fleece enables quick and direct fuser roller lubrication. A particular advantage shows improved capillary action and absorbency. The transfer of the release agent to the fleece using the Wicks ensure optimal wetting of the fleece independently of thermal and geometric tolerances.

Figur 1

eine schematische Schnittdarstellung einer Trennmittelauftragsvorrichtung mit Fixierwalze und

Figur 2

eine perspektivische Darstellung eines oberen Führungsmittels gemäß Figur 1.

An example of the invention is explained in more detail below with reference to the drawing. Show

Figure 1

is a schematic sectional view of a release agent application device with fixing roller and

Figure 2

a perspective view of an upper guide means according to Figure 1.

In an electrographic not shown here in detail Printer or copier is in a heat setting station a release agent application device shown in Figure 1 for applying release agent L to the surface of a. Fuser roller assigned. The basic diagram shows the Fuser roller F, which rotates clockwise. Not shown are the pressure roller of the fuser and the between recording media guided on both rollers. Shown but is the device for applying release agent the surface of the fusing roller F. serves as application element V. a fleece that has a thickness of 0.2 to 0.3 mm. It exists made of polyamide, polyimide or Teflon. The application element V carries silicone oil or another suitable heat resistant Release agent in liquid form preferably on the whole Surface of the fuser roller F on. To ensure this extends the application element V with its entire Width over the entire axial length of the fixing roller F. Das Application element V is also in a predetermined Circumferential area applied to the fixing roller F.

In the operating state, application element V is always available the surface of the fixing roller F in contact. That takes Application element V dirt particles, such as Toner particles or dust carried by the recording medium. To one To ensure proper functioning, the area of the application element V resting on the fixing roller F. either continuously slow, but possibly also in intervals renewed in sections. There is one supply roll, not shown, from which the application element V is withdrawn, as well as a take-up roll, not shown provided that receives the used application element V. The take-up roll is e.g. powered by a motor. The direction of transport of the application element caused by the motor runs against the movement of the fixing roller F, so that the used application element V all by stripping off impurities picked up on the surface of the fixing roller F. carry along and always have a sufficient area relatively fresh Application element V is available.

The peripheral area at which the application element V with the surface the fuser roller F stands by the distance between two parallel to each other in the axial direction of the fixing roller F extending guide elements OB, UB defined. These leadership elements UB, OB are arranged vertically one above the other, so that from an upper guide element OB and a lower one Guide element UB can be spoken. The two leadership elements OB, UB are represented by springs S1, S2, which are in the area the end faces of the guide elements UB, OB arranged are pressed to the surface of the fixing roller F. The order the springs S1, S2 and their direction of action is indicated by arrows FS1, FS1 'can be seen in Figure 2. In the middle of its length the guide elements UB, OB each have one Web ST1, ST2 on. This web ST1, ST2 is in the chassis Fixing station captive due to positive locking. The Form fit is designed so that on the one hand an adequate Local stability of the guide elements UB, OB guaranteed and on the other hand, there is sufficient play that it allowed the guide elements UB, OB over their entire longitudinal extent by means of the springs S1, S2 against the surface of the Press the fuser roller F. This ensures an even one surface pressure of the application element V on the surface the fuser roller F regardless of thermal and geometric Tolerances. The oscillation of the guide elements UB, OB thus ensures an even distribution of the Release agent L.

In addition to her leadership role for application element V the guide elements UB, OB perform another task. In an undercut extending in the upper guide element OB Longitudinal groove LN is a thickened long side LS Wick D retractable. The wick preferably extends over the entire length of the guide elements UB, OB. The the thickened long side LS opposite long side of the Wicks D dips into a gutter UBR that runs lengthways in the lower one Guide element UB extends. The UBR channel is on the upper guide element OB facing side open. The longitudinal groove LN and the channel UBR run parallel to each other. you vertical distance to each other corresponds approximately to the width of the wick D. This means that the wick D essentially without waves, similar to a hanging cloth from the top Guide element OB up to the channel UBR of the lower one. Guide element UB hangs. The arrangement of longitudinal groove LN and Channel UBR is selected so that the wick D is the application element V touched over the entire longitudinal extent. This ensures supplying application element V with release agent L, that is released by the wick D.

The wick D receives the release agent L in two places. To the one is sucked by the wick D immersed in the channel Release agent L by capillary action. By using suitable wick materials such as PTFE, polyamide and Polyimide and its combinations, the capillary action and absorbency for the good distribution of the release agent L supported. The good capillary action also ensures that in areas along the length of the Fuser roller F, in which an increased consumption of release agent L is always a sufficient amount of this release agent is available. The gutter UBR on both ends is closed like a tub, supports the distribution effect of the release agent L. The release agent can be in the Channel UBR very quickly to areas with high release agent requirements flow where it is picked up by wick D on a short path can be.

The actual release agent is supplied through a release agent metering tube R. This release agent metering tube R extends in the axial direction of the fixing roller F in the vicinity of the fixing roller F facing away from the wick D. In the Wick D facing pipe wall are at defined intervals introduced a plurality of openings O, from which release agents L can leak. The release agent metering tube R is preferred closed at one end and preserved at the open Page about a hose and a pump, for example designed feed system release agent L, which only from the Openings O can emerge in the direction of the wick.

For a loss-free approach of the exiting from the openings O. To ensure release agent G to wick D is in an area under the openings O on the surface of the Release agent metering tube R glued an elastic lip. This elastic lip G bridges a distance between the Release agent metering tube R and the wick D over their entire Longitudinal extension. The elastic lip G is under tension with their free end on wick D. The lip G is preferably inclined towards the gutter UBR, whereby a rapid release of the release agent L is guaranteed.

The lower guide element UB, which contains the channel UBR, is so designed that the channel wall in the area of the application element V runs, is lower than the pipe side Wall. Excess release agent L therefore does not flow on the pipe side, but towards application element V. The application element V takes up the excess release agent L, whereby it is transported away.

Claims (8)

1. Release agent application means for applying release agent (L) onto the surface of a fixing drum (F) of an electrographic printer or copier device, comprising

   a pressure member (OB, UB) extending along the fixing drum (F);

   an application element (V) that can be brought into contact with the fixing drum (F) and that lies against guide elements (OB, UB) of the pressure member;

   a release agent delivery (UBR, D) that extends in a region between the guide elements (OB, UB) at that side of the application element (V) facing away from the fixing drum and outputs release agent (L) to the application element (V) in a release agent transfer region, whereby the release agent delivery (UBR, D) comprises:

   a duct (UBR) that is arranged under the release agent transfer region, so that the supplied release agent (L) distributes therein over the usable width of the fixing drum (F),

   a wick (D) immersing into the duct (UBR) that extends from the duct (UBR) to the release agent transfer region and lies against the application element (V) thereat.
2. Release agent application means according to claim 1, comprising a release agent dosing tube (R) that extends along the wick (D) over the usable width of the fixing drum (F) and contains discharge openings through which release agent (L) can be output to the wick (D).
3. Release agent application means according to claim 2, comprising a distance between the release agent dosing tube (R) and the wick (D), and comprising an elastic lip (G) bridging the distance that is coupled liquid-tight to the release agent dosing tube (R) and is inclined in the direction toward the duct (R) [sic], so that release agent (L) emerging from the discharge openings can flow to the wick (D).
4. Release agent application means according to one of the claims 1 through 3, comprising a lower guide element (UB) that contains the duct (UBR) and comprising an upper guide element (OB) that contains an undercut longitudinal channel (LN) into which a thickened long side (LS) of the wick (D) can be pulled.
5. Release agent application means according to one of the claims 1 through 4, comprising an application element (V) transportable opposite the rotational sense of the fixing drum (F), and comprising a duct (UBR) closed at both sides that contains walls of different height, whereby the lower wall lies at the application element (V), so that excess release agent is output to the application element (V).
6. Release agent application means according to one of the claims 1 through 5, comprising a resilient bearing of the pressure member (OB, UB).
7. Release agent application means according to one of the claims 1 through 6, comprising a fleece serving as application element (V), said fleece exhibiting a thickness of 0.2 mm through 0.3 mm.
8. Release agent application means according to claim 7, comprising a fleece composed of polyamide, polyimide or Teflon.

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