GB2054465A - Scraper blade assembly for pressure fixing rollers - Google Patents

Abstract

A pair of cooperating, pressure fixing rollers 12, 14 for an electrophotocopying machine and a scraping device 38, 40 associated with each of the rollers for removing toner accumulated on the rollers. At least one, and preferably each, scraping device includes a blade 42 tangent to one of the rollers and contacting the roller at the leading edge of the blade, and a reinforcement 46 for the blade. The reinforcement has a greater thickness than the thickness of the blade and is contiguous to most of one surface area of the blade but does not extend to the leading edge of the blade. <IMAGE>

Description

SPECIFICATION Scraper blade assembly for pressure fixing rollers This invention relates to photocopying machines, and more particularly to a scraper blade assembly used to clean the pressure fixing rollers of a photocopying machine.

In pressure fixing photocopiers, the developed image is fixed to the copy sheet paper by feeding the copy sheet bearing the unfixed toner between a pair of heated or unheated pressure fixing rollers which cooperate to force the toner particles into the copy sheet. In the course of the fixing process, some of the toner particles adhere to the fixing rollers, which if not removed immediately, may appear on other portions of the copy sheet being processed or on subsequent sheets. It is therefore a common practice to provide a device to remove the excess toner accumulated on the rollers, one such device being a scraper blade. However, there are certain problems attendant with the use of scraper blades, such as annoying squeaks, insufficient wear characteristics, and need for an expensive metal to provide a sharp blade configuration and/or a ground knife edge.In those fixing roller assemblies where the rollers are skewed, i.e. cross each other, there is posed an additional problem of conforming the scraper blade to the surface ofthe roller.

Accordingly, the present invention provides a pair of cooperating pressure fixing rollers for use in an electrophotocopying machine and a scraping device associated with each of said rollers for removing toner accumulated on said rollers, at least one of the said scraping devices including a blade tangent to one of said rollers and contacting said one roller at the leading edge of said blade, and a reinforcement for said blade, said reinforcement having a slightly greater thickness than the thickness of said blade and being contiguous to most of one surface area of the blade but not extending to the leading edge of said blade.

The invention will be better understood from the following non-limiting description of an example thereof given with reference to the accompanying drawings in which: Figure 1 is a perspective view of a pressure fixing roller assembly for a photocopier embodying a preferred example of the invention; Figure2 is an enlarged, side elevational view of the pressure fixing roller assembly shown in Figure 1; Figure 3 is an enlarged, sectional view taken on the vertical plane indicated by the line 3-3 in Figure 1.

Reference is now made to the drawings, wherein there is seen a pressure fixing roller assembly generally designated 10 suitable for fixing toner to a copy sheet without the use of heat in an electrophotocopying machine (not shown). It should be noted, however, that the invention is equally applicable to a pressure fixing roller assembly which does employ heat.The roller assembly 10 includes a pair of pressure fixing rollers 12 and 14 which, instead of being parallel to each other, are skewed with respect to each other, i.e. the top roller 12 is inclined by an angle of about degree with respect to a line perpendicular to the transportation direction of copy paper (not shown) which is fed from a paper guide 15 through the rollers 12 and 14, and the bottom roller 14 is also inclined, but in a direction opposite that of the top roller 12, by an angle of about degree with respect to a line perpendicular to the transportation direction of the copy paper. Accordingly, the axes of the two rollers 12 and 14, when viewed perpendicular to the plane of the copy paper, cross and are inclined relative to each other at an angle of about one degree.The rollers 12 and 14 are cylinders made of hardened steel rotatably supported, respectively, by a pair of upper arms 16 and 18 and a pair of lower arms 20 and 22. Each pair of upper and lower arms, i.e. upper arm 16 and lower arm 20 being a pair, and upper arm 18 and lower arm 22 being a pair, are formed as an integral unit which tapers to a narrow cross section at the juncture 24 of the upper and lower arms. Each of the junctures 24 functions as a common pivot for its respective upper and lower arm.

Pressure is applied to the rollers 12 and 14through the springs 26 and 28. Each of the springs 26 and 28 is mounted on a bolt 34 and 36 respectively each of which passes through its respective upper and lower arm. The pressure is adjusted by rotating sets of nuts 30 and 32 on the shafts 34 and 36 respectively. It can thus be appreciated that the lower roller 14 is fixed while the top roller 12 is slightly movable with respect to the lower roller 14. The rollers 12 and 14 are driven by means of a sprocket wheel 37 and a drive chain and motor (not shown).

In order to remove toner particles which accumulate on each of the rollers 12 and 14, there are provided scraping devices 38 and 40 for the upper and lower rollers 12 and 14 respectively. The upper scraping device 38 includes a blade 42 extending across the full length of the upper roller 12 and disposed in tangential relation thereto. Only the leading edge 44 of the blade 42 contacts the upper roller 12. The blade 42 is reinforced with a similarly shaped member 46, both of which are secured by screws 47 to a bracket 45 which in turn is secured by screws 49 to the upper arms 16 and 18. The lower scraping device 40 also includes a blade 48 extending across the full length of the lower roller 14 and disposed in tangential relation thereto. Only the leading edge 50 of the blade 48 contacts the lower roller 14.The blade 48 is reinforced with a similarly shaped member 52, both of which are secured by screws 51 to a bottom plate 53.

The thickness of the blades 42 and 48 is preferably about 0.008 inch, while the thickness of the reinforcing members 46 and 52 is preferably about 0.012 inch. It should be noted also that the reinforcing members 46 and 52 do not extend out to the leading edges 44 and 50 of the blades 42 and 48 respectively.

The blades 42 and 48 and the reinforcing members 46 and 52 are shown as being one leg in a 2-legged unit, the other leg (bearing the letter a in the drawings) providing a surface for attachment to the arms 16,18, 20 and 22. Of course, the legs 42a, 46a, 48a and 52a are not necessary, as other means of securing the blades 42 and 48 and the reinforcing members 46 and 52 may be used.

The blades 42 and 48 may be formed from carbon steel or stainless steel or non-ferrous material either in the cold worked or heat treated condition or from non-metallic materials having a certain amount of spring characteristics, and obviously do not require a ground edge. The rollers 12 and 14 are skewed with respect to each other, but the design of the scraping devices 38 and 40 enables them to conform to the shape of the rollers 12 and 14 along the entire length of the rollers 12 and 14.

While a particular embodiment of the invention has been shown and particularly described, it should be understood that the invention is not limited thereto since many modifications will occur to one skilled in the art.

Claims (10)

1. A pair of cooperating pressure fixing rollers for use in an electrophotocopying machine and a scraping device associated with each of said rollers for removing toner accumulated on said rollers, at least one of the said scraping devices including a blade tangent to one of said rollers and contacting said one roller at the leading edge of said blade, and a reinforcement for said blade, said reinforcement having a slightly greater thickness than the thickness of said blade and being contiguous to most of one surface area of the blade but not extending to the leading edge of said blade.

2. A pair of rollers according to claim 1, wherein the blade is formed from carbon steel or stainless steel.

3. A pair of rollers according fo claim 1 or 2 wherein one of the rollers is fixed and the other of said rollers is slightly movable with respect to said one roller.

4. A pair of rollers according to claim 1,2 or 3 wherein the thickness of the blade is about 0.008 inch and the thickness of the reinforcing member is about 0.012 inch.

5. An electrophotocopying machine including a pair of rollers according to any one of claims 1-4, wherein at least one of the pressure fixing rollers is inclined with respectto a line perpendiculartothe transportation of the copy paper in the machine.

6. A machine according to claim 5 wherein the rollers include a top and a bottom roller, and the top roller is inclined by an angle of about 2 degree and the bottom roller is inclined at an angle of about 2 degree in a direction opposite that of the top roller.

7. A machine according to claim 6 when dependent on claim 4, wherein the scraping device comprises a two legged unit, one of said legs comprising the blade and the reinforcement for the blade, and the other of said legs comprising a surface for attaching said blade and reinforcement to the photocopying machine.

8. A machine according to claim 7, wherein the blade conforms to the shape of the roller along the entire length thereof.

9. Apairofrollersfora photocopying machine substantially as herein particularly described with reference to and as illustrated in the accompanying drawings.

10. An electrophotocopying machine substantially as herein particularly described with reference to and as illustrated in the accompanying drawings.