Title of Invention: Device for applying release agent to the surface of a fixing roller of an electrographic printer or copier
Abstract: A printer or copier which operates by transfer printing has a fixing roller for affixing toner to the recording medium. A release agent, or parting oil, is applied to the roller by a dosing tube having openings through which the release agent flows to a wick. An application element is moved over the roller between the wick and the roller for cleaning and application of the release agent. The wick is held in guide elements and the lower guide element has a duct for collecting excess release agent and applying it to the application element.
Detailed Description: Part PAC: DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Part PAR: A release agent application means (shown in FIG. 1) for applying release agent L onto the surface of a fixing drum F is allocated in a thermal fixing station in an electrographic printer or copier device that is not shown in detail here. The schematic illustration shows the fixing drum F, which rotates in a clockwise sense. The pressure drum of the fixing station and the recording medium guided between the two drums are not shown. However, the device for applying release agent onto the surface of the fixing drum F is shown. A fleece that exhibits a thickness of 0.2 through 0.3 mm serves as an application element V. It is composed of polyamide, polyimide or Teflon. The application element V applies silicone oil or some other suitable, heat resistant release agent onto the entire surface of the fixing drum F, preferably in a liquid form. In order to assure this, the application element V has its entire width extending over the entire axial length of the fixing drum F. Over and above this, the application element is applied against the fixing drum F in a pre-determined circumferential region.
Part PAR_2: In the operating condition, the application element V is constantly in contact with the surface of the fixing drum F. The application element V thereby picks up dirt particles such as, for example, toner particles or dust entrained by the recording medium. In order to assure a faultless function, the region of the application element V lying against the fixing drum F is preferably renewed in sections either continuously slowly but potentially also in chronological intervals. To that end, a supply reel VV from which the application element V is unwound as well as a take-up reel AV that winds up the used application element V is provided. The take-up reel AV is driven, for example, by a motor MO. The transport direction of the application element V produced by the motor MO runs opposite the motion of the fixing drum F, so that the used application element V entrains all contaminants picked up by being stripped from the surface of the fixing drum F, and an adequate surface of relatively fresh application element V is always available.
Part PAR_3: The circumferential region at which the application element V resides contacts with the surface of the fixing drum F is defined by the spacing of two guide elements OB and UB extending parallel to one another in an axial direction of the fixing drum F. These guide elements UB and OB are arranged vertically above one another, so that they can be identified as an upper guide element OB and a lower guide element UB. The two guide elements UB and OB are pressed to the surface of the fixing drum F by springs S1 and S2 that are arranged in the region of the end faces of the guide elements UB and OB. The arrangement of the springs S1 and S2 and their action direction is illustrated by arrows FS1 and FS1' in FIG. 2. In the middle of their longitudinal extent, the guide elements UB and OB respectively comprise a rib ST1 and ST2. These ribs ST1 and ST2 are seated so as to be captive in the chassis of the fixing station by a positive lock. The positive lock is implemented such that, on the one hand, an adequate location stability of the guide elements UB and OB is assured and, on the other hand, adequate play is present that allows the guide elements UB and OB to be pressed against the surface of the fixing drum with the springs S1 and S2 over their entire longitudinal extent. This assures a uniform planar pressing of the application element V against the surface of the fixing drum F independently of thermal and geometrical tolerances. Oscillation of the guide elements UB and OB, which is made possible by the aforementioned play in the mounting and the springs S1 and S2, thereby assures a uniform distribution of the release agent L.
Part PAR_4: The guide elements UB and OB fulfill a further task in addition to their guide function for the application element V. A thickened longitudinal side LS of a wick D can be pulled into an undercut longitudinal channel LN extending in the upper guide element OB. The wick preferably extends over the entire length of the guide elements UB and OB. The long side of the wick D lying opposite the thickened longitudinal side LS immerses into a duct UBR that extends longitudinally in the lower guide element UB. The duct UBR is open at the side facing toward the upper guide element OB. The longitudinal channel LN and the duct UBR proceed parallel to one another. Their vertical spacing from one another approximately corresponds to the width of the wick D. Thus, the wick D hangs essentially without wave formation or undulations, similar to a hanging cloth, from the upper guide element OB into the duct UBR of the lower guide element UB. The arrangement of the longitudinal channel LN and the duct UBR is selected such that the wick D contacts the application element V over the entire longitudinal extent. This assures a supply of the application element V with the release agent L that is output by the wick D.
Part PAR_5: The wick D picks up the release agent L at two locations. First, the wick D extending into the duct UBR sucks up the release agent L that is present there by capillary action. The capillary action and absorbency for a good distribution of the release agent L is promoted by employing suitable wick materials such as PTFE, polyamide and polyimide and their combinations. The good capillary action also assures that an adequate quantity of this release agent is always available in regions along the longitudinal extent of the fixing drum F in which an elevated consumption of the release agent L ensues. The duct UBR that is closed at both end faces to form a trough shaped space supports the distributing effect of the release agent L. The release agent L can flow very rapidly in the duct to the regions of the fixing drum F which require a greater quantity of the release agent, where it can be picked up from the duct by the wick D on a short path to the drum surface.
Part PAR_6: The actual release agent delivery ensues with a release agent dosing tube R. This release agent dosing tube R extends in the axial direction of the. fixing drum F in the region near that side of the wick D facing away from the fixing drum F. Openings O from which release agent L can emerge are introduced at defined intervals in that tube wall facing toward the wick D. The release agent dosing tube R is preferably closed at one end and receives release agent L at the open side via a delivery system fashioned, for example, of a hose and a pump, the release agent L being only capable of emerging from the openings O in the direction of the wick.
Part PAR_7: In order to assure a loss-free delivery of the release agent L emerging from the openings O to the wick D, an elastic lip is glued on the surface of the release agent dosing tube R in a region under the openings O. This elastic lip G bridges a distance between the release agent dosing tube R and the wick D over the entire longitudinal extent thereof. The elastic lip G has its free end lying against the wick D under pre-stress. The lip G is preferably inclined in the direction of the duct UBR, this assuring a fast flow of the release agent L.
Part PAR_8: The lower guide element UB, which contains the duct UBR, is implemented such that the duct wall that proceeds in the region of the application element V is lower than the wall at the tube side. Excess release agent L thus does not flow off at the tube side but toward the application element V. The application element V picks up the excess release agent L, which is thus carried off.
Part PAR_9: Although other modifications and changes may be suggested by those skilled in the art, it is the intention of the inventors to embody within the patent warranted hereon all changes and modifications as reasonably and properly come within the scope of their contribution to the art.


{'bibliographic_information': "{'Patent Number': '060729783', 'Series Code': '9', 'Application Number': '1173170', 'Application Type': '1', 'Art unit': '282', 'Application Filing Date': '19980727', 'Title of Invention': 'Device for applying release agent to the surface of a fixing roller of an electrographic printer or copier', 'Issue Date': '20000606', 'Number of Claims': '10', 'Exemplary Claim Number(s)': '1', 'Assistant Examiner': 'Noe ; William A.', 'Primary Examiner': 'Grimley; Arthur T.', 'Number of Drawing Sheets': '1', 'Number of figures': '2'}", 'source_file': './grant/2000/pftaps20000606_wk23.txt', 'source_data': 'USPTO-Grant'}