JPH0432456A - Paper discharging device - Google Patents

Abstract

PURPOSE:To enable the use of all kinds of sheets from thin to thick in a paper discharging device for an electrophotographic technology applied copying machine by providing a postcard passage with a paper discharging auxiliary guide in the state of facing a discharge roller position so as to curve the postcard in the reverse direction to the curve generated to the postcard. CONSTITUTION:A paper discharge guide 10 for guiding a postcard 2, delivered from a heat roller fixing device, onto a tray 12 is formed of a paper discharging auxiliary guide 10a and a paper discharging lower guide 10b. The rear end part of the paper discharging lower guide 10b is circularly curved along a paper discharging drive roller 11a so as to have a guide face lower than the paper discharging drive roller 11a. The upper auxiliary guide 10a is disposed opposedly to the lower guide 10b, and the part, corresponding to the drive roller 11a, of the upper auxiliary guide 10a is curved protrusively upward. The postcard 2 is thereby curved in the reverse direction to remove its curl.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a paper ejecting device that ejects recorded recording paper onto a paper ejection tray in a recording device such as a copying machine or a laser beam printer that utilizes electrophotographic technology. Regarding.

[Conventional technology]

This type of recording device extracts recording paper cut into a predetermined size from a paper cassette, transports it, transfers a toner image formed by electrophotography, and then passes it through a heat roller fixing device. The toner image is fixed on the recording paper. The heat roller fixing device includes a heat roller and a pressure roller, and the heat roller disposed on the side in contact with the toner image is a metal roller whose surface is coated with Teflon or the like, and is used to press the recording paper against the heat roller. In order to obtain a nip portion of 3 to 4 mm in the pressure roller, an elastic layer such as silicone rubber is formed on the surface of the core metal.

When the recording paper passes through such a heat roller fixing device and the toner image is fixed, it is heated and pressurized while being curved along the surface of the heat roller at the nip portion, so that the heat The recording paper sent out from the roller fixing device retains its curvature and curls.

If the curled recording paper is ejected onto the paper ejection tray as it is, the ejection alignment will be poor, and it will be difficult to perform double-sided printing in which the recording paper is turned over and recorded again.
The curvature is removed by curving the paper discharge guide in a direction opposite to the curvature.

A paper ejection mechanism having such a function of removing the curling tendency is disclosed in Japanese Patent Application Laid-Open No. 60-50547 and Japanese Patent Application Laid-Open No. 64-53957.

[Problem to be solved by the invention]

However, the amount of curl of recording paper varies depending on the thickness of the recording paper used, and the thicker the paper, the greater the amount of curl. Therefore, if the amount of curvature of the paper ejection guide is set to an appropriate amount to remove the curvature of thin recording paper, the curvature of thick recording paper cannot be sufficiently removed; If you set it so that it can do so, there is a problem that thin recording paper will curl backwards. It was difficult to equally remove the curvature of the paper (postcard).

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to eliminate the curvature of recording paper caused by a heat roller fixing device, thereby making it possible to equally use recording paper ranging from thin to thick.

[Means to solve the problem]

In order to achieve this object, the present invention includes a paper ejection guide that guides the recording paper sent out from the heat roller fixing device, and a paper ejection roller that conveys the recording paper sent out to the paper ejection guide. In the paper ejecting device, the postcard is moved in a direction opposite to the direction in which the postcard is curved by passing through the heat roller fixing device so that the postcard used as the recording paper faces the path of the postcard at the position of the ejecting roller. The present invention is characterized in that a paper ejection auxiliary guide in the shape of a postcard cap is curved to an appropriate amount to remove the curling tendency.

[Effect]

The paper ejection auxiliary guide acts to remove the large curling of postcards, which are thick recording paper, but since its width of action is limited to the path of the postcard, it has little effect on thin PPC paper, and the PPC paper is No reverse curls. Therefore, it is possible to prevent curling of recording paper from thin to thick.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 4 is a longitudinal sectional side view of a laser beam printer equipped with a paper discharge device according to the present invention. Recording paper 2 cut into a predetermined size and stored in paper cassette 1 is extracted by paper feed roller 3 and conveyed to registration rollers 4 . The registration rollers 4 adjust the timing of conveyance of the recording paper 2 so that the toner image formed on the surface of the photosensitive drum 5 by electrophotography is aligned with the recording paper 2. The recording paper 2 is conveyed so as to be in contact with the surface of the photosensitive drum 5, and while in contact with the recording paper 2, a transfer electric field is applied from the back side by a transfer device 6, so that the toner image on the photosensitive drum 5 is electrostatically transferred. The recording paper 2 on which the toner image has been transferred is peeled off from the surface of the photosensitive drum 5 and conveyed to the heat roller fixing device 7. The heat roller fixing device 7 fuses and fixes the toner image on the recording paper 2 while passing the recording paper 2 between a heating roller 8 and a pressure roller 9. The recording paper 2 sent from the heat roller fixing device 7 to the paper ejection guide 10 is ejected onto the paper ejection tray 12 by the paper feeding force of the paper ejection roller 11 . A fixing mechanism mainly consisting of a heat roller fixing device 7, a paper ejection guide 10, and a paper ejection roller 11
Since the paper ejection mechanism based on It can be expanded around.

The fixing mechanism is removable.

As shown in FIG. 5, the heating roller 8 of the heating roller fixing device ff17 is arranged on the side that contacts the toner image holding surface of the recording paper 2, and is a metal roller made of aluminum or the like whose surface is coated with Teflon or the like. A heater 8b is arranged at the center of the heater 8a. The heater 8b of the heating roller 8 is controlled to generate heat so that the temperature of the surface thereof is 170 to 200°C. The pressure roller 9 is formed by forming an elastic layer 9b of silicone rubber or the like on the outer periphery of a core metal 9a, and is pressed against the heating roller 8 so as to obtain a nip portion having a width of 3 to 5 mm.

The recording paper 2 passing through such a heat roller fixing device 7 is heated and pressurized (approximately 0.5 to 1.0
kg), the fixed recording paper 2 sent out from the heat roller fixing device 7 is curled so that the heat roller 8 side is concave.

This amount of curl is similar to that of general PPC paper (60 to 90 g/
rr! ”) is small, so the heat roller fixing device'rL
7 and pulled by the paper ejection roller 11, the paper is corrected to the extent that it does not become a problem. However, when the recording paper 2 is a postcard, the rigidity is high, so the pulling by the paper ejection roller 11 does not sufficiently correct the curling, resulting in curling (the amount of curling is 15 to 20 mm).
.

In order to remove the curl caused by the heating roller 8 that causes this curl, the fixed postcard (recording paper 2) sent out from the heating roller fixing device 7 is guided to be ejected onto the paper ejection tray 12. As shown in FIG. 6, the paper ejection guide 10 of the paper ejection mechanism is provided with an upper paper ejection auxiliary guide 10a and a lower paper ejection guide 10b. This paper ejection lower guide 10b is a guide that acts commonly on general PPC paper and postcards, and its rear end portion is circularly guided along the paper ejection drive roller lla so that it becomes a guide surface lower than the paper ejection drive roller lla, which will be described later. It is curved in an arc. The paper ejection auxiliary guide 10a, which is curved in an arc shape so that its rear end portion forms a guide surface in the opposite direction to the curling direction of the recording paper 2, has a width substantially equal to the width of the postcard passage, and faces the postcard passage. It is provided so as to face the lower paper discharge guide 10b. The paper ejection roller 11 picks up the recording paper 2 at a substantially central position of the curved guide portion of the paper ejection auxiliary guide 10a.
It is arranged so as to sandwich and apply a conveyance force to it, and the paper ejection drive roller lla and the paper ejection driven roller 1 ],
b.

The outer peripheral surface of the paper ejection drive roller lla and the paper ejection auxiliary guide 10
The gap G between the paper sheet and the sheet a is set to about 1 to 3 mm, and provides a curvature removing force that bends the postcard being held and conveyed by the paper discharge rollers 11 in a direction opposite to the curvature direction. By setting the amount of curvature of the rear end portion of the paper ejection auxiliary guide 10a to be an appropriate amount to remove the curvature caused by the postcard passing through the heat roller fixing device 7, the curl of the postcard can be reduced. The amount can be kept to 5 mm or less.

The position A of the rear end of the paper ejection auxiliary guide 10a influences the traveling direction of the recording paper 2 ejected from the paper ejection guide 10. The recording paper 2 is given an upwardly convex bend to remove the curvature, so if the leading edge of the ejected recording paper 2 is directed too downward, the recording paper 2 will be bent at two points. As shown by the chain line, the paper progresses and becomes curled or stacked upside down on the paper discharge tray 12, resulting in a problem that significantly deteriorates the integrity of the paper discharge. In order to prevent this problem from occurring, the leading edge of the recording paper 2 and the ejected paper should be aligned at point B, where the leading edge of the recording paper 2 lands on the paper ejection tray 12, regardless of whether general PPC paper or postcard paper is used as the recording paper 2. The contact angle θ and distance Q between the recording paper 2 and the discharge tray 12 are obtained such that the recording paper conveyance force f1 is greater than the sum of the frictional force f2 of the tray 12 and the elastic force f2 due to the reverse curl of the recording paper 2. be able to do so. According to the experimental results, the contact angle θ is approximately 20°.
It was found that the distance @Q is preferably around 170 mm, and that as the contact angle θ increases, adverse effects due to reverse curl tend to occur.

In this way, you can reduce the curl of the postcard and make it look like a typical P.
It is possible to use PC paper. In fact, not only was it possible to prevent misalignment of the ejected recording paper 2 due to curling, but also double-sided recording was performed, in which the recording paper 2 on which an image was recorded on the front side was turned over and the image was recorded again. However, there were no more problems such as paper jams, transfer misalignment, or transfer plates.

By the way, the paper ejection drive roller lla and the paper ejection driven roller ll
The trailing edge of the recording paper 2 that has passed through the nipping area b is conveyed (pushed out) by the frictional force with the paper ejection active roller lla due to the weight of the recording paper 2, and falls onto the paper ejection tray 12. However, by bending the paper ejection auxiliary guide 10a to eliminate curling, the recording paper 2 tends to curl backwards, and when the contact angle θ between the leading edge of the recording paper 2 and the paper ejection tray 12 increases, the frictional force f, Since the (conveyance resistance) increases, the recording paper 2 cannot be pushed out only by the frictional force due to its own weight. In order to prevent such a phenomenon from occurring, as shown in FIGS.
Gear-shaped kicking roller l with a diameter slightly larger than a
It is good to provide lc. In this way, the rear end of the recording paper 2 that has passed through the nipping area between the paper ejection driving roller 11a and the paper ejection driven roller llb is engaged with the kicking roller llc and pushed out. However, the paper ejection drive roller lla
If the difference between the diameters of the kick-off roller llc and the kick-off roller llc is too large, the amount of deformation of the recording paper 2 will become large, and there is a risk that the recording paper 2 will be plastically deformed or the trailing edge will be damaged. Preferably,
In the case of the paper discharge beating roller lla having a diameter of 20 mm, the diameter of the kicking roller llc is about 21 mm. If the level difference is of this level, the recording paper 2 can pass through while being deformed by the elastically deformable enclosure.

In order to ensure that the trailing edge of the recording paper 2 is pushed out by the paper ejection drive roller lla without using the kick-out roller llc, as shown in FIG. A kick-off auxiliary roller 1lcl that presses the recording paper 2 against the paper ejection driving roller lla is provided downstream of the recording paper holding area by the driven roller llb to reduce the frictional force between the rear end portion of the recording paper 2 and the paper ejection opening roller 11a. It is best to try to reduce it. The pushing force of this kick-off auxiliary roller llc is approximately several grams, and the effect can be reliably obtained.

The kicking roller llc and the kicking auxiliary roller Ild
Of course, it is also possible to use them together.

Further, as shown in FIG. 10, the protrusions of the kicking roller llc can be made to have a sawtooth shape with a relatively large pitch so that they can easily engage with the trailing edge of the recording paper 2.

The paper ejection mechanism as described above is effective in a laser beam printer that can arbitrarily use thin recording paper (general PPC paper) and thick recording paper (postcards). However, for laser beam printers that do not use thick recording paper 2, the paper ejection guide 10 as described above is used.
The countermeasure for removing curvature is an excessive function, and it is preferable not to use the auxiliary guide 10a on paper ejection whose rear end portion is curved as described above.

Figures 1 to 3 show that it is possible to selectively and easily manufacture two types of laser beam printers: a laser beam printer that has the function of removing curvature from postcards, which are thick recording paper, and a laser beam printer that does not. The paper ejection mechanism (paper ejection guide) is shown.

The lower paper discharge guide 10b is commonly used in two types of laser beam printers. 11 Paper guide 10c is general PP
In order to be suitable for guiding C paper (recording paper), it is formed into a roughly rectangular shape so as not to give the recording paper 2 any flexure to remove the curling habit.

The auxiliary paper ejection guide 10a described above is configured to be removably attached to the lower side of the paper ejection upper guide 10c with a width facing the postcard transport path width W.

For this attachment/detachment, an engagement cut/raise 10d and a positioning dowel portion 10e are formed in the vertical portion of the paper discharge upper guide 10c. Paper ejection auxiliary guide 10 having a roughly slit shape and having an arcuate curved portion formed on its horizontal portion to remove the curved tendency.
A positioning hole 10f that fits into the positioning dowel portion 10e is formed in the vertical portion of the positioning hole 10f. The paper ejection auxiliary guide 10a has a positioning dowel portion 10e of the paper ejection upper guide 10c.
While fitting the positioning hole 10f into the positioning hole 10f, the end edge of the vertical portion is engaged with the cut and raised portion 10d, and the end of the horizontal portion is pressed against the lower surface of the paper discharge upper guide 10c to be attached with elastic force.

According to such a paper ejection mechanism, the auxiliary paper ejection guide 10a can be attached to and removed from the upper paper ejection guide 10C without using any special tools, so the auxiliary paper ejection guide 10a can be attached to and removed from the upper paper ejection guide 10C as needed. This makes it easy to connect the unnecessary paper ejection auxiliary guide 10a to the paper ejection upper guide 10c.

〔Effect of the invention〕

As described above, according to the present invention, it is possible to prevent curling by eliminating curling caused by a heat roller fixing device on general PPC paper, which is thin recording paper, and postcards, which are thick recording paper. In addition, if you wish, you can easily attach and remove a paper ejection guide to prevent postcards from curling, making this paper ejection device suitable for electrophotographic devices that use a variety of recording papers. It can be done.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view of a paper ejection mechanism in which a paper ejection auxiliary guide for removing curling disease to prevent curling is removable, and FIG. 2 is a front view thereof. , FIG. 3 is a perspective view of an auxiliary guide on paper ejection, FIG. 4 is a longitudinal side view of a laser beam printer to which the paper ejection device of the present invention is applied, and FIG. 5 is a longitudinal side view of its fixing mechanism and paper ejection mechanism. 6 is a vertical cross-sectional side view of the paper ejection guide and the paper ejection roller section, FIG. 7 is a perspective view of the paper ejection roller section, FIGS. 8 and 10 are side views of the paper ejection roller, and FIG. 9 FIG. 3 is a side view of the paper ejection guide section. 7... Heat roller fixing device, 10... Paper ejection guide, 10a... Paper ejection upper auxiliary guide, 10b... Paper ejection lower guide, 11...
...paper ejection roller, lla...paper ejection drive roller, llc...kicking roller,
lid...Kicking auxiliary roller. Figure 1

Claims (1)

[Scope of Claims] 1. A paper ejection device including a paper ejection guide that guides recording paper sent out from a heat roller fixing device, and a paper ejection roller that conveys the recording paper sent out to the paper ejection guide. , the curvature of the postcard in a direction opposite to the direction in which the postcard is curved when passing through the heat roller fixing device so that the postcard used as the recording paper faces the path of the postcard at the position of the paper ejection roller; A paper ejecting device characterized in that a paper ejecting auxiliary guide approximately the width of a postcard is curved to an appropriate amount for removal. 2. The paper ejection device according to claim 1, wherein the paper ejection auxiliary guide is detachably provided on the paper ejection guide. 3. The paper ejection device according to claim 1 or 2, wherein the paper ejection auxiliary guide is elastically engaged with a cut-and-raised portion formed on the paper ejection guide. 4. The paper ejecting device according to claim 1, wherein the paper ejecting roller located on the inside of the curve of the paper ejecting auxiliary guide is provided with a recording paper kicking part projecting from its outer peripheral surface. 5. The paper ejection device according to claim 1, wherein the paper ejection auxiliary guide has an auxiliary roller that presses the recording paper against a paper ejection roller located on the inside of a curve of the paper ejection auxiliary guide. .