JPH1140U - Image forming device peeling device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to provide a highly reliable and practical peeling device of an image forming apparatus capable of reliably peeling a paper or the like without causing a paper jam or the like. SOLUTION: A radius of curvature of a cross section of a leading edge portion of a peeling member in a direction perpendicular to an axial direction of the fixing roller and perpendicular to an axis of the fixing roller is R, a leading edge portion of the peeling member and the fixing roller. In the case where G is a gap with respect to the peripheral surface portion, and when R ≦ 0.2 mm, the configuration is such that 0 <G ≦ 1.5 mm.

Description

[Detailed description of the invention]

[0001]

[Technical field to which the invention belongs]

 The present invention relates to a peeling device used for an image forming apparatus such as an electrophotographic copying machine, and particularly to a peeling device used for a fixing device.

[0002]

[Prior art]

 Conventionally, as this kind of peeling device, there is one as disclosed in Japanese Patent Application Laid-Open No. 53-81241. This is because abutting members that come into contact with the fixing roller outside the effective image area of the fixing roller are attached to both ends of the pick-off blade, and the abutting members come into contact with the fixing roller so that a predetermined distance is established between the fixing roller and the pick-off blade. It is configured so that a clearance is formed. More specifically, JP-A-53-81241 discloses that a clearance of about 0.1 to 0.5 mm is provided between a fixing roller and a pick-off blade.

However, in the case of the above-described apparatus, since the pick-off blade is formed of a single plate, it is difficult to achieve straightness in manufacturing, and the edge portion of the pick-off blade and the peripheral surface of the fixing roller are difficult to achieve. There is a problem that variation occurs along the axial direction of the fixing roller in the gap, and paper jams and breakage of the leading edge of the paper called a dog ear occur. The peeling device is basically a non-contact type, but the non-contact portion is in the effective image area of the fixing roller, and the abutting member is located outside the effective image area of the fixing roller. In contact with the surface. Therefore, the surface of the fixing roller is damaged by the abutting member that contacts the surface of the fixing roller, and the release agent such as silicone oil applied to the surface of the fixing roller is scraped off. In particular, in the latter case, the scraped release agent wraps around the non-contact portion of the pick-off blade, spills out of the gap with the fixing roller, and adheres to the copy paper to be fixed, causing image damage. There was a problem.

Japanese Patent Application Laid-Open No. 53-81241 also discloses an apparatus using an abutment roller instead of an abutment member. In this case, the abutment roller is slightly eccentric. However, since the gap between the pick-off blade and the surface of the fixing roller changes, there is a fatal problem for the peeling device that a peeling failure occurs.

Therefore, the present inventors have already proposed a peeling device for a completely non-contact type image forming apparatus capable of solving the above-mentioned problems and optimally setting a gap between the fixing roller and the peeling member. (Japanese Utility Model Application No. 61-13305).

[0006] This is because a suspension body supported on both side plates of the apparatus main body, a plurality of plate-like members supported by the suspension body and divided into a plurality of plate-like members, and a leading edge portion of each of the divided members and a fixing roller are provided. And a peeling member formed with a predetermined gap between itself and the peripheral surface portion.

[0007]

[Problems to be solved by the invention]

 However, the device proposed by the present inventors has the following problems. That is, in the case of the above proposed device, although the basic configuration capable of solving the conventional problems is shown, when such a device is actually manufactured, the shape of the tip edge of the divided member and the tip of the divided member Depending on the gap between the edge portion and the peripheral surface portion of the fixing roller, there is a possibility that a paper jam occurs or the paper cannot be peeled at all. Therefore, in the case of the completely non-contact type peeling device as proposed above, further technical considerations are added in order to ensure that the paper can be peeled off without causing a paper jam or the like. It was a need.

[0008] As a separation claw of a contact type different from that of JP-A-53-81241, there is a separation claw disclosed in JP-A-61-236577, which is disclosed in JP-A-61-236577. The gazette describes that the radius of curvature of the tip of the separation claw is reduced (for example, 0.1 mm or less, preferably 0.05 mm or less).

However, Japanese Patent Application Laid-Open No. Sho 53-81241 discloses a so-called non-contact type exfoliating device in which the exfoliating member does not come into contact with the fixing roller. In addition, they are so-called contact-type peeling devices in which the peeling member and the fixing roller are in contact with each other, and both have different configurations based on the premise thereof, and naturally have a different mechanism for peeling the sheet by the peeling member.

Therefore, in the above-mentioned Japanese Patent Application Laid-Open Nos. 53-81241 and 61-236577, the gap G between the leading edge of the peeling member and the peripheral surface of the fixing roller, and the leading edge of the peeling member are disclosed. The technical significance of the radius of curvature R of the part is completely different. Furthermore, in a contact-type peeling device as disclosed in JP-A-61-236577, it is meaningless to provide a gap between the leading edge of the peeling member and the peripheral surface of the fixing roller.

On the other hand, in a non-contact type peeling device as disclosed in Japanese Patent Application Laid-Open No. 53-81241, the gap between the leading edge portion of the peeling member and the peripheral surface portion of the fixing roller is variously examined and optimized to some extent. However, it has never been proposed to consider the gap between the leading edge of the peeling member and the peripheral surface of the fixing roller in relation to the radius of curvature of the leading edge of the peeling member. Had not been.

[0012]

[Means for Solving the Problems]

 Therefore, the present invention has been made to solve the above-mentioned problems of the prior art, and the object thereof is to provide a method of reliably removing paper and the like without causing a paper jam or the like. An object of the present invention is to provide a highly practical peeling device for an image forming apparatus.

That is, the present invention has a fixing roller and a pressing roller that is in pressure contact with the fixing roller, and conveys the sheet while nipping and pressing the sheet between the fixing roller and the pressing roller. An image forming apparatus comprising a fixing device for fixing the toner image, a separating member provided near the peripheral surface of the fixing roller, and a predetermined gap formed between a leading edge portion of the separating member and a peripheral surface portion of the fixing roller. In the peeling device, a radius of curvature of a cross section in a direction perpendicular to an axial direction of the fixing roller at a leading edge portion of the peeling member and perpendicular to the axis of the fixing roller is R, When the gap between the roller and the peripheral surface is G, when R ≦ 0.2 mm, 0 <G ≦ 1.5 mm.

[0014]

[Action]

 The present inventors have found that the radius of curvature R of the leading edge of the peeling member and the gap G between the leading edge and the peripheral surface of the fixing roller are important factors that determine the peelability of the sheet. The peeling performance of these devices was tested, and the radius of curvature R of the leading edge portion and the gap G between the leading edge portion and the peripheral surface of the fixing roller were actually tested. The value was determined.

[0015]

【Example】

 The present invention will be described below based on the illustrated embodiment.

FIG. 2 shows a fixing device of an electrophotographic copying machine provided with a peeling device according to one embodiment of the present invention. In the drawing, reference numeral 1 denotes a fixing roller, and the outer periphery of the fixing roller 1 is covered with a heat-resistant elastic material such as silicone rubber, and heating elements 2 and 2 are disposed inside the fixing roller. As shown in FIG. 3, the fixing roller 1 has a small diameter at a center portion of the portion divided into three in the axial direction, and both end portions continuous on both sides have a large diameter at an end portion side. It is formed in a tapered shape. The fixing roller is not limited to this, and may be a cylindrical roller whose outer diameter is uniform in the axial direction. The fixing roller 1 has shafts 3 protruding from both ends thereof rotatably supported on side plates 4 and 5 of the copying machine main body via bearings 6 and 7.

A pressure roller 8 is pressed against the fixing roller 1 from below, and the outer periphery of the pressure roller 8 is also covered with a heat-resistant elastic material such as silicone rubber to improve the fixing property. To improve it. Although not shown, the shaft of the pressure roller 8 is rotatably supported on a side plate of the copying machine body via a bearing, similarly to the shafts 3 and 3 of the fixing roller 1. When the fixing roller 1 and the pressing roller 8 convey a sheet 9 made of a copy paper or the like holding a toner image while nipping and pressing the sheet, the heat of the fixing roller 3 heated by the heating elements 2 and 2 and the fixing roller 1 The toner image is fixed on the sheet by a pressing force between the sheet and the pressing roller 8.

In this embodiment, the peeling member 10 is provided near the peripheral surface of the fixing roller 1. The peeling member 10 is composed of plate-like dividing members 11, 12, and 13 divided into three along the axial direction of the fixing roller 1, and between these dividing members 11, 12, and 13. Are provided with a predetermined interval α. From the viewpoint of dispersion of the peeling force, it is preferable that the width of the divided members 11, 12, and 13 is large and the distance α between the divided members 11, 12, and 13 is small. Each of the divided members 11, 12, and 13 of the peeling member 10 has a structure rotatably supported by a suspension body 14 via a shaft 15, and the leading edge portions 11a, 12a, and 13a are provided with fixing rollers. 1 is set so as to maintain a predetermined gap G with respect to the peripheral surface portion.

A pair of adjusting screws 16, 17 are screwed and held in the suspension body 14, and lower ends thereof are shoulders located on both sides of the upper surface of the divided members 11, 12, 13 as shown in FIG. The structure is in contact with the parts 11b and 12b. Although FIG. 2 shows only a configuration in which the lower ends of the adjusting screws 16 and 17 abut against the shoulders 11b and 12b of the divided members 11 and 12, the shoulders of the other divided members 13 are shown. Also, the lower ends of the adjusting screws 16 and 17 are in contact with each other. The divided members 11, 12, 13 rotatably supported on the shaft 15 are held at a predetermined angular posture by adjusting screws 16, 17, and the leading edge portions 11a, 12a, Adjustment of the gap G between 13a and the peripheral surface of the fixing roller 1 is performed by tightening or loosening the adjusting screws 16 and 17. In other words, if it is desired to set the gap G to be narrower than the state shown in the figure, the divided members 11, 12, and 13 are tightened by a predetermined amount as if the outer adjustment screw 16 is moved downward. Therefore, the gap G can be set to be narrower. On the other hand, if it is desired to set the gap G wider, an operation opposite to the above-described operation may be performed.

If the corners 11c, 12c, and 13c of the divided members 11, 12, and 13 of the peeling member 10 are formed in a substantially right angle, the toner surface is rubbed by the corners 11c, 12c, and 13c at the time of peeling. As a result, there may be a case where a dull streak occurs. Therefore, in this embodiment, the corners 11c, 12c and 13c are formed in an arc shape having a predetermined curvature.

The suspension 14 has a structure in which both ends are hooked and supported on a shaft 18 fixed to the side plates 4 and 5 of the copying machine main body. The suspension 14 may have a structure that can be easily fixed to the side plate via a magnet or the like.

By the way, in order to clarify the dimensions and shape of a peeling member capable of actually peeling a sheet in the peeling device having the above configuration, the inventors of the present invention prototyped a peeling device as shown in FIG. An experiment was conducted to obtain a practically peelable range by changing the parameters of the above. In FIG. 1, R indicates the shape of the distal end of the peeling member 10, and was evaluated based on the radii of curvature of the distal edges 11a, 12a, and 13a of the dividing members 11, 12, and 13. β is the angle between the lower surface of the peeling member 10 and the horizontal line, G is the gap between the front edge portions 11a, 12a, 13a and the peripheral surface of the fixing roller 1, and θ is the gap between the front edge portions 11a, 12a, 13a and the fixing roller 1. The angle between the closest position to the peripheral surface and the horizontal line passing through the center O of the fixing roller 1 is shown.

The apparatus used in the experiment used a fixing roller having a diameter of 50 mm, and the surface temperature of the fixing roller was set at 150 ° C. Using a 90 μm-thick A4 size transfer sheet as a sheet, a peeling test was performed under an environment of normal temperature and normal humidity. At this time, the radius of curvature R of the leading edge portions 11a, 12a, 13a of the divided members 11, 12, 13 is determined by using a magnifying projector (produced by Nippon Kogaku Co., Ltd., trade name: PROFIL P ROJECTOR MODEL V-16). And projected on a screen. The gap G between the leading edge and the peripheral surface of the fixing roller was measured using a thickness gauge made of a thin film made of a polyimide resin.

Table 1 shows the results of a test of the peelability when the radius of curvature R and the gap G of the leading edge portion of the peeling member were variously changed. In Table 1, 〇 indicates the case where the sheet was reliably peeled off, and x indicates the case where the sheet could not be peeled due to paper jam or peeling failure.

[0025]

[Table 1]

As is evident from the above results, when the shape of the tip edge portion has a radius of curvature R and a gap G of R ≦ 0.2 mm, even if the shape is considerably large as G ≦ 1.5 mm, it is ensured. It was found to be peelable. Also, it was found that when 0.2 mm <R <0.7 mm, peeling failure occurs unless at least the gap G is set to 525 μm or less. Furthermore, when 0.7 mm ≦ R ≦ 1.0 mm, it was found that peeling failure occurred unless the gap G was set to 300 μm. It has been found that when the radius of curvature R is 1.0 mm or more, peeling failure occurs even if the gap G is set small.

As described above, the radius of curvature R of the leading edge portions 11a, 12a, 13a of the peeling member 10 and the gap G between the leading edge portions 11a, 12a, 13a and the peripheral surface of the fixing roller 1 are set within the above ranges. By doing so, it is possible to manufacture a practical peeling device that can reliably peel off the sheet without causing a paper jam or peeling failure.

By the way, if the radius of curvature R and the gap G of the leading edge of the peeling member satisfy the above conditions, the peeling can be surely performed, but if the radius of curvature of the leading edge is small, the peeling of the peeling member can be performed. A state in which the leading edge pierced the surface of the sheet occurred, and a wavy mark sometimes appeared on the surface of the peeled sheet. The wavy marks generated on the surface of the sheet are not necessarily generated, and are of a size that does not cause a problem in a normal state.

In order to find out more preferable conditions of the apparatus in which the wavy mark is not generated as described above, the inventors of the present invention varied the angle β in the range where the peeling was possible in Table 1 and carried out the above test. The same peeling test was performed under the same conditions as described above. In Test Example 1, the radius of curvature R of the leading edge portion of the peeling member was changed in a range of 0.2 mm or less, and the gap G was changed in a range of 1.5 mm or less. In Test Example 2, the radius of curvature R was changed in the range of 0.2 <R <0.7 mm, and the gap G was changed in the range of 500 μm. In Test Example 3, the radius of curvature R was changed in a range of 0.7 ≦ R ≦ 1.0 mm and the gap G was changed in a range of 300 μm. In Table 2, 〇 indicates the case where no wavy mark was generated on the back surface of the sheet, and x indicates the case where a wavy mark was generated on the back surface of the sheet.

[0030]

[Table 2]

As is clear from Table 2, when the radius of curvature R of the leading edge of the peeling member is changed within a range of 0.2 mm or less and the gap G is changed within a range of 1.5 mm or less. If the angle β is in the range of 10 to 30 degrees, it is found that no wavy mark is generated on the sheet. When the radius of curvature R is changed in the range of 0.2 <R <0.7 mm and the gap G is changed in the range of 525 μm, and the radius of curvature R is set in the range of 0.7 ≦ R ≦ 1.0 mm. When the gap G is changed within the range of 300 μm, if the angle β is within the range of 0 to 10 degrees, no wavy mark is generated on the sheet, and the sheet can be surely peeled off. I found that I could do it.

Further, the peelability of the sheet was tested by changing the angle θ variously, and it was found that the angle θ hardly affected the peelability of the sheet. However, since other members are disposed around the fixing roller 1, the angle θ is preferably in the range of 25 to 60 degrees. The angle θ is not limited to the above range, but may be other than this.

In the above-described embodiment, the structure in which the peeling member 10 is divided into three parts has been described, but the present invention is not limited to this number. Further, the material of the peeling member 10 is not specified (iron, aluminum, resin or the like may be used), but a material having heat resistance is better. In particular, if the surface of the peeling member 10 is coated with Teflon (registered trademark), the peeling performance can be further improved. Also, the structure in which both ends of the suspension body 14 are supported by the shaft 18 fixed between the side plates 4 and 5 of the copying machine main body has been described. However, the present invention is not limited to this and is not shown. The fixing device may be supported by a shaft fixed between side plates of the fixing device main body. Further, in the above-described embodiment, the peeling device of the copying machine is described as the peeling device of the image forming apparatus. However, the present invention is not limited to this, and the peeling device of the image forming device such as a printer and a facsimile is used. It can also be applied to

In the above-described embodiment, a mechanism (such as an ISIL) that prevents toner from adhering to the sheet tip is provided in the process before the sheet enters the fixing device, and as shown in FIG. For example, a configuration is also conceivable in which the toner 19 does not adhere in the range 9b of 7 to 15 mm. Here, ISIL is an abbreviation for an inside image lamp. The interside image lamp is an LED (light emitting diode) lamp used to eliminate black stripes at the edge of a copy. With such a configuration, the toner does not adhere to the fixing roller 1 within a predetermined range from the leading end of the sheet 9, and therefore, the stable peeling of the leading end of the sheet from the fixing roller 1 can be performed. As a result, it is possible to prevent a problem such as breakage of the sheet tip (for example, dog ear) and poor peeling. This configuration is particularly effective for the toner 19 that is strongly attracted to the fixing roller 1.

[0035]

[Effect of the invention]

 This invention has the above configuration and operation, and can provide a highly reliable and practical peeling device of an image forming apparatus capable of reliably peeling off a sheet without causing a paper jam or the like.

[Brief description of the drawings]

FIG. 1A is an explanatory diagram showing parameters for obtaining practicable numerical values of a peeling device of an image forming apparatus according to the present invention, and FIG. 1B is an enlarged view of a portion B in FIG. FIG.

FIG. 2 is a schematic configuration diagram of a fixing device including a peeling device of a copying machine according to the present invention.

FIG. 3 is a plan view of the identification landing device.

FIG. 4 is a schematic configuration diagram showing another embodiment of a toner fixed on a sheet to be peeled off.

[Explanation of symbols]

1: fixing roller, 8: pressure roller, 9: sheet, 10 ...
Separating members, 11, 12, 13 ... divided members, 11a, 12
a, 13a: leading edge, R: radius of curvature of the leading edge, G: gap between the leading edge and the peripheral surface of the fixing roller.

Claims (1)

[Utility model registration claims] A fixing device for fixing a toner image on a sheet by conveying a sheet while nipping and pressing the sheet between the fixing roller and the pressure roller. A peeling member provided in the vicinity of a peripheral surface of the fixing roller, and a predetermined gap is formed between a leading edge portion of the peeling member and a peripheral surface portion of the fixing roller. The radius of curvature of the cross section in the direction perpendicular to the axial direction of the fixing roller at the leading edge of the member and the surface perpendicular to the axis of the fixing roller is R, the radius of curvature of the leading edge of the peeling member and the peripheral surface of the fixing roller are When the gap is G, when R ≦ 0.2 mm, 0 <
A separation apparatus for an image forming apparatus, wherein G ≦ 1.5 mm.