JPH0727475Y2 - Image forming device peeling device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] The present invention relates to a peeling device used in an image forming apparatus such as an electrophotographic copying machine, and more particularly to a peeling device used in a fixing device.

[Prior Art] Conventionally, as a peeling device of this type, there is one disclosed in Japanese Patent 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 pickoff blade, and the abutting members come into contact with the fixing roller to provide a predetermined clearance between the fixing roller and the pickoff blade. Is formed.

However, in the case of the above apparatus, since the pickoff blade is formed by a single plate, it is difficult to obtain straightness in manufacturing, and the pickoff blade is fixed in the gap between the tip edge portion and the fixing roller peripheral surface. There is a problem in that variations occur along the axial direction of the rollers, which causes paper jams and bending of the leading edge of the paper called dog-ear. Also,
The peeling device is basically a non-contact type,
The non-contact portion is in the effective image area of the fixing roller, and outside the effective image area of the fixing roller, the abutting member is in contact with the surface of the fixing roller. for that reason,
The abutting member that contacts the surface of the fixing roller may damage the surface of the fixing roller or scrape off the release agent such as silicon oil applied to the surface of the fixing roller. Particularly, in the latter case, the release agent scraped off wraps around the non-contact part of the pickoff blade, spills from the gap between the fixing roller and adheres to the copy paper or the like which is fixed, and causes image damage. There was a problem.

Similarly, Japanese Patent Application Laid-Open No. 53-81241 also discloses a device using an abutting roller instead of the abutting member, but in this case, the abutting roller may have some eccentricity or the like. However, since the gap between the pickoff blade and the surface of the fixing roller changes, there is a fatal problem for the peeling device that peeling failure occurs.

Therefore, the present inventors have already proposed a peeling device for a completely non-contact type image forming apparatus which solves the above-mentioned problems and allows the gap between the fixing roller and the peeling member to be optimally set (actual application). (Sho 61-13305).

This is composed of a suspension body supported by both side plates of the apparatus main body, and a suspension member supported by the suspension body and divided into a plurality of plate-like members, and a tip edge portion of each divided member and a peripheral surface portion of the fixing roller. And a peeling member having a predetermined gap formed therebetween.

[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 proposed device, although showing a basic configuration that can solve the conventional problems, when actually manufacturing such a device,
Depending on the shape of the leading edge portion of the dividing member and the gap between the leading edge portion of the dividing member and the peripheral surface portion of the fixing roller, paper jam may occur or the paper may not be peeled at all. Therefore, in the case of the completely non-contact type peeling device as proposed above, further technical study needs to be performed in order to prevent the paper jam or the like and to surely peel the paper. I had one.

[Means for Solving Problems] Therefore, the present invention was made in order to solve the problems of the above-mentioned conventional technology, and the purpose thereof is to prevent paper jams and the like and to ensure the reliability. Another object of the present invention is to provide a highly reliable and practical peeling device for an image forming apparatus capable of peeling a sheet or the like.

That is, the invention has a fixing device having a fixing roller and a pressure roller in pressure contact with the fixing roller, and fixes the toner image on the sheet by conveying the sheet while sandwiching and pressing the sheet with the fixing roller and the pressure roller. And a peeling member provided in the vicinity of the peripheral surface of the fixing roller, and a predetermined gap is formed between the tip edge portion of the peeling member and the peripheral surface portion of the fixing roller. When the radius of curvature of the cross section of the tip edge portion of the peeling member in the direction orthogonal to the axial direction of the fixing roller is R, and the gap between the tip edge portion of the peeling member and the peripheral surface portion of the fixing roller is G, R ≦ 0.2 mm In case of 0 <G ≦ 1.5 mm, in case of 0.2 mm <R <0.7 mm, 0 <G ≦ 525 μm, and in case of 0.7 mm ≦ R ≦ 1.0 mm, 0 <G ≦ 300 μm. Is configured.

[Operation] The present inventors have found that the radius of curvature R of the leading edge portion of the peeling member and the gap G between the leading edge portion and the peripheral surface portion of the fixing roller are important factors that determine the peelability of the sheet. , Prototypes of peeling devices in which these are variously changed, the peeling performance of these devices is tested, and the radius of curvature R of the tip edge portion and the gap G between the tip edge portion and the peripheral surface portion of the fixing roller that can be actually peeled are tested. The value of was calculated.

[Embodiment] The present invention will be described below based on an illustrated embodiment.

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

Further, a pressure roller 8 is pressed against the fixing roller 1 from below, and the pressure roller 8 is also coated with a heat-resistant elastic body such as silicone rubber to improve the fixing property. It has become. Although not shown in the figure, the shaft of the pressure roller 8 is also rotatably supported by a side plate of the copying machine main body via a bearing, like the shafts 3 and 3 of the fixing roller 1. When the sheet 9 made of copy paper or the like holding the toner image is conveyed while being nipped and pressed by the fixing roller 1 and the pressure roller 8, 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 the pressure contact force between the pressure roller 8 and the pressure roller 8.

By the way, in this embodiment, the peeling member 10 is arranged in the vicinity of the peripheral surface of the fixing roller 1. This peeling member 10
Is composed of plate-shaped dividing members 11, 12, 13 which are divided into three along the axial direction of the fixing roller 1, and a predetermined space is provided between the dividing members 11, 12, 13 respectively. Are provided at intervals α. From the viewpoint of dispersion of the peeling force, it is preferable that the width dimension of the dividing members 11, 12, 13 is large and the dimension α of the dividing members 11, 12, 13 is small. Each of the split members 11, 12, 13 of the peeling member 10 has a structure in which it is rotatably supported by a suspension body 14 via a shaft 15.
The tip edge portions 11a, 12a, 13a are set so as to maintain a predetermined gap G with respect to the peripheral surface portion of the fixing roller 1.

A pair of adjusting screws 16 and 17 are screwed and held on the suspension body 14, and the lower end portion thereof is, as shown in FIG.
The structure is such that it abuts on shoulders 11b, 12b located on both sides of the upper surfaces of 1, 12, 13. In addition, in FIG. 2, a dividing member
Only the configuration in which the lower ends of the adjusting screws 16 and 17 are in contact with the shoulders 11b and 12b of the eleventh and twelve is shown, but other dividing members are shown.
The lower ends of the adjusting screws 16 and 17 are also in contact with the shoulder of 13. A split member 11 rotatably supported on a shaft 15,
12 and 13 are held in a predetermined angle posture by adjusting screws 16 and 17, and the tip edge portion 11 of the split members 11, 12, and 13 is held.
The gap G between the a, 12a, 13a and the peripheral surface of the fixing roller 1 is adjusted by tightening or loosening the adjusting screws 16, 17. That is, when it is desired to set the gap G to be narrower than the state shown in the figure, if the adjusting screw 16 located outside is tightened by a predetermined amount as it is moved downward,
As a result, the split members 11, 12, 13 rotate in the direction of arrow A in FIG. 2, and the gap G can be set to be narrower. On the other hand, when it is desired to set the gap G to be wider, the operation reverse to the above operation may be performed.

Corners 11c, 12c, 13 of the respective split members 11, 12, 13 of the peeling member 10
If c is formed in a substantially right angle shape, the toner surface may be rubbed by the corners 11c, 12c, 13c at the time of peeling, and as a result, a dull streak may occur. Therefore, in this embodiment, the corner portions 11c, 12c, 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 by a shaft 18 fixed to the side plates 4 and 5 of the main body of the copying machine. The suspension 14 may have a structure that is easily fixed to the side plate via a magnet or the like.

By the way, in order to clarify the size and shape of the peeling member capable of actually peeling a sheet in the peeling device having the above-described structure, the present inventors prototyped a peeling device as shown in FIG. Experiments were carried out by changing the value to determine the practically peelable range. In FIG. 1, R indicates the shape of the tip of the peeling member 10, and the dividing member 11,
The evaluation was made by the radius of curvature of the tip edge portions 11a, 12a and 13a of 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 leading edge portions 11a, 12a, 13a and the peripheral surface portion of the fixing roller 1, and θ is the circumference of the leading edge portions 11a, 12a, 13a and the fixing roller 1. The closest position to the surface portion indicates the angle with the horizontal line passing through the center O of the fixing roller 1.

As the apparatus used in the experiment, a fixing roller having a diameter of 50 mm was used, and the surface temperature of the fixing roller was set to 150 ° C. Then, using an A4 size transfer sheet having a thickness of 90 μm as a sheet, a peelability test was conducted under an environment of normal temperature and normal humidity. At this time, the tip edge portion 11 of the split members 11, 12, 13
The radii of curvature R of a, 12a, and 13a are enlarged projectors (made by Nippon Kogaku Co., Ltd., trade name: PROFIL PROJECTOR MODEL V-1
6) was used to project on a screen for measurement. Further, the gap G between the tip edge portion and the peripheral surface portion of the fixing roller was measured using a thickness gauge made of a thin film made of polyimide resin.

Table 1 shows the results when the peelability was tested when the radius of curvature R and the gap G of the tip edge portion of the peeling member were variously changed. In Table 1, ◯ indicates that the sheet can be reliably peeled off, and x indicates paper jam or peeling failure.
Each case shows that the sheet could not be peeled off.

As is clear from the above results, when the radius of curvature R and the gap G of the tip edge portion are R ≦ 0.2 mm, G ≦
It was found that even if the size was as large as 1.5 mm, peeling could be reliably performed. It was also 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, 0.7mm ≦ R ≦ 1.0mm
In the case of, it was found that peeling failure occurs unless the gap G is 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.

Thus, the tip edge portions 11a, 12a, 13a of the peeling member 10
By setting the radius of curvature R and the gap G between the leading edge portions 11a, 12a, 13a and the peripheral surface portion of the fixing roller 1 within the above range, the sheet can be reliably peeled without causing a paper jam or peeling failure. It is possible to manufacture a practical peeling device that can be used.

By the way, if the radius of curvature R and the gap G of the tip edge portion of the peeling member satisfy the above conditions, the peeling can be surely performed, but if the radius of curvature of the tip edge portion is small, the tip edge portion of the peeling member is The surface of the sheet sometimes pierces, and a wavy mark may appear on the surface of the peeled sheet. The wavy mark generated on the surface of the sheet does not always occur, and is a problem that does not cause a problem in a normal state.

Therefore, the inventors of the present invention have found out in Table 1 to find more preferable conditions of the apparatus in which the wavy mark as described above does not occur.
In the peelable range, the peelability test was conducted under the same conditions as the above test while changing the angle β variously. In Test Example 1, the radius of curvature R of the tip edge portion of the peeling member is R.
In the range of 0.2 mm or less and the gap G in the range of 1.5 mm or less. In test example 2, the radius of curvature R is 0.2 <R
The gap G was changed within the range of <0.7 mm and within the range of 500 μm. In Test Example 3, the radius of curvature R is 0.7 ≦ R ≦ 1.0 mm
And the gap G is changed within the range of 300 μ. In Table 2, ◯ indicates the case where no wavy mark was generated on the back surface of the sheet, and x indicates the case where the wavy mark was generated on the back surface of the sheet.

As is apparent from Table 2 above, the radius of curvature R of the tip edge portion of the peeling member is within a range of 0.2 mm or less, and the gap G is 1.5 mm.
It was found that when the angle was changed within the following range, no wavy mark was generated on the sheet when the angle β was within the range of 10 to 30 degrees. Also, the radius of curvature R is 0.2 <R <0.7
mm, when the gap G is changed within the range of 525 μm, and when the radius of curvature R is changed within the range of 0.7 ≦ R ≦ 1.0 mm and the gap G is changed within the range of 300 μm, It was found that when the angle β is in the range of 0 to 10 degrees, no wavy mark is generated on the sheet, and the sheet can be reliably peeled off.

Further, the peelability of the sheet was tested by changing the angle θ variously, and it was found that the angle θ had almost no effect on the peelability of the sheet. However, since other members are arranged 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, and it goes without saying that it may be other than this.

Although the peeling member 10 is divided into three parts in the above-described embodiment, the number is not limited to this. Although the material of the peeling member 10 is not specified (iron, aluminum, resin, etc. may be used), it is preferable that the material has heat resistance. Particularly, if the surface of the peeling member 10 is coated with Teflon (registered trademark), the peeling performance can be further improved. Further, although the suspension 14 has a structure in which both ends are supported by the shaft 18 fixed between the side plates 4 and 5 of the main body of the copying machine, the structure is not limited to this and the illustration is omitted. The structure may be supported by a shaft fixed between the side plates of the fixing device body. Further, in the above-described embodiments, the peeling device of the copying machine is mentioned as the peeling device of the image forming apparatus, but the devised device is not limited to this, and the peeling device of the image forming device such as a printer or a fax machine. Can also be applied to.

Further, in the above-described embodiment, a mechanism (ISIL or the like) that prevents toner from adhering to the leading edge of the sheet is provided in the process before the sheet enters the fixing device, and as shown in FIG.
For example, in the range 9b of 7 to 15 mm from the tip 9a of the toner 19
It is also conceivable that the structure prevents the adherence. Where IS
IL is an abbreviation for Inside Image Lamp. Inside image lamp is an LED (light emitting diode) lamp used to erase black streaks at the edge of the copy. With such a configuration, the toner is not attracted to the fixing roller 1 within a predetermined range from the front end of the sheet 9, and thus the stable front end of the sheet can be separated from the fixing roller 1. As a result, it is possible to prevent problems such as bending of the leading edge of the sheet (for example, dog ears) and defective peeling. This configuration is particularly effective for the toner 19 which is strongly attracted to the fixing roller 1.

[Advantages of the Invention] This invention has the above-described configuration and operation, and provides a highly reliable and practical peeling device for an image forming apparatus that can reliably peel a sheet without causing a paper jam or the like. be able to.

[Brief description of drawings]

FIG. 1 (a) is an explanatory view showing parameters for obtaining a feasible numerical value of the peeling device of the image forming apparatus according to the present invention, and FIG. 1 (b) is an enlarged view of a portion B of FIG. 1 (a). , Second
FIG. 3 is a schematic configuration diagram of a fixing device having a peeling device of a copying machine according to the present invention, FIG. 3 is a plan view of an identification fixing device, and FIG. 4 is another embodiment of toner fixed on a sheet to be peeled. It is a schematic block diagram which shows an example. [Explanation of Codes] 1 ... Fixing roller 8 ... Pressure roller 9 ... Sheet 10 ... Peeling member 11, 12, 13 ... Splitting member 11a, 12a, 13a .... Tip edge portion R ... Tip edge portion Radius of curvature G: gap between the leading edge and the peripheral surface of the fixing roller

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-60-189780 (JP, A) JP-A-53-143341 (JP, A) JP-A-60-19183 (JP, A) Actual development Sho-62- 127564 (JP, U) Actually opened 62-68167 (JP, U) Actually opened 63-26855 (JP, U)

Claims (1)

[Scope of utility model registration request] 1. A fixing device for fixing a toner image on a sheet, comprising a fixing roller and a pressure roller in pressure contact with the fixing roller, and transporting the sheet while sandwiching and pressing the sheet with the fixing roller and the pressure roller. In the peeling device of the image forming apparatus, the peeling member is provided near the peripheral surface of the fixing roller, and a predetermined gap is formed between the tip edge portion of the peeling member and the peripheral surface portion of the fixing roller. When the radius of curvature of the cross section of the leading edge of the member in the direction orthogonal to the axial direction of the fixing roller is R, and the gap between the leading edge of the peeling member and the peripheral surface of the fixing roller is G, R ≦ 0.2 mm Is 0
<G ≦ 1.5 mm, 0.2 mm <R <0.7 mm, 0 <
When G ≦ 525 μm and 0.7 mm ≦ R ≦ 1.0 mm, 0 <
A peeling device for an image forming apparatus, characterized in that G ≦ 300 μm.