JPS63213881A - Pressure fixing device - Google Patents

Abstract

PURPOSE:To prevent the occurrence of image curvature and to miniaturize a device by specifying relations among the angle of crossing, the angle of nip, the set angle of a fixing roll to the shaft of an image carrier, and the set angle of a pressure roll to the shaft of the image carrier. CONSTITUTION:Specific conditions are satisfied in relations among the angle of crossing, the angle of nip, the set angle alpha of a fixing roll 1 to the shaft of the image carrier, and the set angle beta of a pressure roll 2 to the shaft of the image carrier. That is, the set angle alpha of the fixing roll 1 to the shaft of the image carrier is made larger than the set angle beta of the pressure roll 2 to the shaft of the image carrier, and the angle of nip is made smaller than 1/2 of the angle of crossing. Thus, the problem of image curvature is resolved since transverse deviation scarcely occurs in the rear end part of a recording material even if the interval between a fixing position and a transfer position is shortened, and an electrophotographic device using the pressure fixing device is miniaturized.

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention is utilized in the technical field of pressure fixing an unfixed image formed on a recording material in an electrophotographic apparatus, and particularly in the field of pressure fixing of an unfixed image formed on a recording material in an electrophotographic apparatus. The present invention relates to a pressure fixing device in which the above pressure fixing is performed between a fixing roller and a pressure roller that are in contact with each other at a crossing angle.

(Prior Art and Problems) An electrophotographic apparatus is configured, for example, as shown in FIG. 4 of the accompanying drawings.

In this known device, the recording paper, which is the recording material, is fed to the paper feed roller 2.
1 and 22 to the registration rollers 23 and 24, and after being temporarily stopped, the registration rollers 23 and 24 send it out in time with image formation, and the registration roller 2
3 and 24, and reaches a photosensitive drum 27, which is an image carrier, through a guide 26. As is well known, the image formed on the photoreceptor drum 27 is transferred to the recording paper, and after passing through the conveyance section 28, the recording paper is guided to the fixing input logite 29, and is placed between the opposing fixing roller 31 and pressure roller 32. The film is fed into the film, where it is pressure-fixed.

In such a known device, the recording paper is fed with its leading edge parallel to the axes of the registration rollers 23, 24 and the photosensitive drum 27. When the recording paper enters between the fixing roller 31 and the pressure roller 32, the fixing roller 31 and the pressure roller 32 are arranged so that their rotational axes have an intersecting angle, in order to reduce the shock caused by the leading edge. The special one shown in Fig. 3, where the two are arranged in parallel, is adopted. In FIG. 3, the fixing roller 31 is connected to the axis 11a of the reference axis 30 which is parallel to the leading edge P1 of the recording paper P, that is, which is parallel to the axes of the registration rollers 23, 24 and the photosensitive drum 27. is set at an angle α', and the pressure roller 32 is set at a position where its shaft 32a is inclined at an angle β'. Therefore, the intersection angle γ′ of both rollers 31 and 32
is γ′=α′−β′. Also, both rollers 31,
the angle of the contact area of 32 with respect to the center line 15 or the reference line 30;
In other words, the nip angle δ′ is δ′=(α′+β”)X(S4
).

With the fixing roller 31 and the pressure roller 32 having such a set angle, the fixing roller 31 exerts a force 31c in a direction perpendicular to its axis 31a and a force 31c on the pressure roller 32 with respect to the recording paper.
exerts a force 32c in the perpendicular direction to its axis 32a, so
The recording paper receives the resultant force F'. This resultant force F
If ' is not perpendicular to the reference line 30, the recording paper will shift laterally.

At that time, if the fusing position and the transfer position are set with a sufficient distance from each other in relation to the length of the recording paper, even if the recording paper shifts laterally at the fixing position, the transfer will not be affected in any way. . However, in recent years, there has been a demand for miniaturization of devices, and there is a tendency to move the fixing position and transfer position closer together. At that time, if the distance between the fixing position and the transfer position is shorter than the length of the recording paper, while the recording paper is being fixed and causing lateral displacement, the rear of the recording paper remaining at the transfer position will be displaced laterally. There is a problem in that the image becomes inaccurate due to the amount of time. This becomes more noticeable as the distance becomes shorter than the length of the recording paper.

(Means for Solving the Problems) The present invention solves the above-mentioned problems, and even in the fixing roller and pressure roller having an intersecting angle, almost no lateral displacement of the recording material occurs, and the electrophotographic The first objective is to provide a pressure fixing device that can be miniaturized.

The present invention is configured as follows to achieve the above object. That is, the recording material is passed through a nip portion between a fixing roller that is in contact with the unfixed image and a pressure roller that is in pressure contact with the fixing roller, and the unfixed image on the recording material is pressed. In the fixing device, the relationships among the intersection angle, the nip angle, the set angle of the fixing roller with respect to the axis of the image carrier, and the set angle of the pressure roller with respect to the axis of the image carrier satisfy the following conditions (A) and (B). A pressure fixing device characterized by:

(A) The setting angle of the fixing roller with respect to the axis of the carrier is larger than the setting angle of the pressure roller with respect to the axis of the image carrier.

(B) The nip angle is smaller than one half of the crossing angle.

(Example) Hereinafter, the present invention will be described in detail based on the accompanying drawings.

As shown in FIG. 2, the pressure fixing device of this embodiment has the following features:
A pressure roller 2 contacts the fixing roller l from below and rotates under a set pressure. A cleaner 6 is disposed on the right side of the fixing roller l, and is housed in a support 4 attached to a frame 3 and receives elastic force from a spring 5.
is impregnated with silicone oil as a mold release agent. The frame 3 of the pressure roller 1 is provided with a scraper puff for removing toner and the like adhering to the pressure opening 1, and a scooping sheet 8 that retains the peeled toner and the like in the frame together with the scraper. Note that the frame 9 of the pressure roller 2 is also provided with a similar scraper l opening and scooping sheet 11. A fixing entrance guide 12 for guiding the recording material P between the fixing roller l and the pressure roller 2 is attached to the frame body 9.

The fixing roller l and pressure roller 2 as described above are parallel to the leading edge PI of the recording paper P, as shown in FIGS. 1(A) and 1(B).
That is, it is set at an inclination angle with respect to the reference line IO which is parallel to the axis of the registration roller and the photosensitive drum. That is, the set angle of the fixing roller l is α, and the set angle of the pressure roller is β. Here, the angles α and β are assumed to take positive values on one side of the reference line 10 and negative values on the other side (hereinafter, the same applies to other angle settings). 1 (A) and (B) show the case where the fixing roller l and the pressure roller 2 are on opposite sides with respect to the reference line IO, or in that case, α and β are values with opposite signs. will be taken.

Thus, the intersection angle γ between the rotation axes 1a and 2a of both rollers 1 and 2 is written as γ=α−β. Further, the angle of the center line 5 of the contact area of both rollers 1 and 2 with respect to the reference line lO, that is, the nip angle δ is δ=(α+β) X (H). The fixing roller l and the pressure roller 2 have a conveying force lc, 2c in a direction perpendicular to the respective rotation axes 1a and 2a.
However, the force F, which is the vector combination of these forces, acts on the recording material as a conveyance force. At this time, since a release agent is applied to the fixing roller l by the cleaner 6, the surface friction is reduced, and therefore the conveying force 2c of the pressure roller 2 becomes larger than the conveying force 1c of the fixing roller l. the result,
The resultant force F becomes a vector in a direction approaching the conveying force 2c.

In order to direct the resultant force F in a direction perpendicular to the reference line 10, in this embodiment, 1α1>1βI (1)1δIllγI
/2 (2) The above formulas (t) and (2) are provided.

For example, in a device equipped with formulas (1) and (2) above, even if the distance between the fixing device and the transfer position is set shorter than the length of A-4 size paper, The amount of lateral deviation of the paper is 1 ml or less, and the image curvature at the rear edge is also OK.
It was confirmed that it could be suppressed to 0.31-. In addition, in conventional devices that do not satisfy the above formulas (1) and (2), the amount of lateral shift is 3 to 41, and the image curvature is 0.5 mm to 1.0 mm.

(Effects of the Invention) As described above, the present invention changes the setting of the fixing roller and the pressure roller, which have an intersecting angle between the rotating axes, and We decided to satisfy two conditions: the nip angle should be larger than the set angle of the pressure roller, and the nip angle should be smaller than half of the intersection angle, so the fixing position and transfer Even if the pitch interval is shortened, most of the lateral displacement occurs at the rear end of the recording material, which solves the problem of image distortion, making it possible to greatly downsize electrophotographic devices that use pressure fixing devices. This has the effect of

[Brief explanation of the drawing]

1A and 1B are plan views showing the angular relationship between the fixing roller and the pressure roller of the apparatus according to the embodiment of the present invention, FIG. 2 is a sectional view showing the vicinity of the roller in FIG. 1, and FIG. This figure is a plan view showing the angular relationship between the fixing roller and the pressure roller of a conventional apparatus, and FIG. 4 is a sectional view showing an outline of an electrophotographic apparatus using the roller of FIG. 3. 1...Fuser roller 2...
・・・・・・Pressure roller α・・・・・・・・・Fixing roller setting angle β・・・・・・・・・−・・・・Pressure roller setting angle γ・・・・・・・・・・・・Intersection angle δ・・・・・・・・・・・・Nip angle Patent applicant Canon Co., Ltd. Agent Patent attorney Toru Fujioka (A) Figure 1 (B)

Claims (1)

[Scope of Claims] A recording material is passed through a nip portion between a fixing roller in contact with an unfixed image and a pressure roller in pressure contact with the fixing roller, the rotational axes of which rotate relative to each other at an intersecting angle. In an apparatus that pressure fixes a printed image, the relationship among the intersection angle, nip angle, set angle of the fixing roller with respect to the axis of the image carrier, and set angle of the pressure roller with respect to the axis of the image carrier meet the following conditions (A), ( A pressure fixing device comprising B). (A) The setting angle of the fixing roller with respect to the axis of the image carrier is larger than the setting angle of the pressure roller with respect to the axis of the image carrier. (B) The nip angle is smaller than one half of the crossing angle.