JPH09204112A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the sticking of a waterdrop to a paper sheet after fixing caused by dew condensation by providing respective specific first and second waterdrop sticking preventing means. SOLUTION: A chute 21 for leading the paper S after fixing to a paper ejecting roller 5 is provided between a fixing device 4 and the ejecting roller 5. The inside surface of the chute 21, that is, the inside surfaces facing each other of upper and lower chute plates 22 are covered with a water absorbing sheet (first waterdrop sticking preventing means) 31 made of felt, a high polymer absorber, etc., and the similar water absorbing sheet (second waterdrop sticking preventing means) 32 is wound over all around the periphery of the roller 5 as well. In these water absorbing sheets 31 and 32, width larger than or equal to the width of the carried sheet S is secured. Since moisture vaporized from the sheet S is absorbed into the water absorbing sheet 31, the dew condensation does not occur, that is, the moisture is prevented from being the waterdrop and meeting the sheet S. Further, the absorbing sheet 32 is wound on the surface of the roller 5 as well, so that the sheet S passing through the roller 5 is not adversely affected by the dew condensation.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic process such as a copying machine and a printer,
In particular, the present invention relates to a technique for preventing water droplets due to dew condensation that occurs after a toner image is heat-fixed from adhering to the paper, or removing it when it adheres.

[0002]

2. Description of the Related Art In an image forming apparatus such as a copying machine using an electrophotographic system, it is necessary to fix an unfixed toner image formed on a sheet to make it a permanent image. As a toner image fixing method, a heating and pressure fixing method in which a toner melted by heating is fused on a sheet while applying pressure is most widely used. There are various fixing devices for implementing this method, but a heating roll type is generally used. This type of apparatus includes a heating roll heated by an infrared lamp and the like, and a pressure roll that is appropriately pressed against the heating roll and abuts against the heating roll. The unfixed toner image adhered to is fixed by heating and applying pressure. The sheet on which the toner image has been fixed passes through a plate-shaped guide member or the like, and then is ejected to the outside of the machine by the ejection roller.

By the way, in such a fixing system, when the paper is heated by the heating roller, water contained in the paper is evaporated, and the evaporated water adheres to the guide member on the downstream side as a water drop. In some cases, so-called dew condensation occurred. When this dew condensation occurs on the guide member, water drops adhere to the paper, causing various problems such as dirt on the toner image, paper jam, paper wrinkles, and improper storage on the paper discharge tray. In particular, if the paper is conveyed in the state of being attached to the paper in the form of water droplets, streaks will occur on the paper, and the image quality will be greatly impaired. To prevent the adverse effect of dew condensation, Japanese Patent Laid-Open No. 6-118827 discloses that
Among the pair of upper and lower guide members, a device has been proposed in which the lower guide member is composed of a plurality of rollers, and water droplets adhering to these rollers are absorbed by a water droplet absorbing member.

[0004]

The above-mentioned device mainly deals with the dew condensation of the lower guide member with which the paper comes into contact, but the water evaporated from the paper also adheres to the upper guide member. There is also a possibility that condensation will occur. The paper sent out from the pair of fixing rollers may curl due to non-uniformity of the water content on the upper surface and the lower surface, and may come into contact with the upper guide member as well. Adheres to the upper surface of the paper and is discharged without being removed. In addition, if the amount of evaporated water generated is large due to the environment of use such as temperature and humidity, it is also possible that dew condensation may occur on the discharge roller. If this happens, it is inevitable that water drops will adhere to the paper, and the water drops cannot be removed. Is. That is, it was not possible to completely prevent the water droplets from adhering to the paper.

The present invention has been made in view of the above circumstances, and provides an image forming apparatus capable of almost completely preventing water droplets due to dew condensation from directly adhering to a sheet or removing water droplets adhering to a sheet. It is an object.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to achieve the above object, and is a fixing device for heating a paper to fix an image on the paper, and both sides of the paper sent from the fixing device. A guide means disposed opposite to the first guide means, a conveying means for receiving the paper from the guide means and conveying the paper to the next processing means, and a first means for preventing water droplets from adhering to both sides of the paper passing through the guide means. And a second water drop adhesion preventing means for preventing water drops from adhering to both sides of the sheet passing through the conveying means.

According to the present invention, the water evaporated from the paper passing through the fixing device is condensed on the guide means or the conveying means on the downstream side of the fixing device, and the water droplets are attached to the paper before or when the water droplets are attached. Water droplets on both sides of the
This is prevented by the water drop adhesion preventing means and the second water drop adhesion preventing means. As a result, it is possible to prevent the toner image on the paper from being soiled or wrinkled, and also to prevent the paper jam.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. (1) First Embodiment (Prevention of Water Droplet Adhesion on Paper) FIGS. 1A to 1C show different types of copying machines to which the first embodiment is applied. The first embodiment is intended to prevent water droplets from adhering to the paper.

A. Configuration of First Embodiment In the copying machine of FIG. 1A, an image of an original document set on the apparatus main body 1 forming the outer shell is formed on the surface of the photoconductor drum 2 by an image forming unit (not shown). While being converted and formed as a toner image, the toner image is transferred onto the upper surface of the sheet S by passing between the photoconductor drum 2 and the transfer drum 3, and then the sheet S passes through the fixing device 4. Then, the unfixed toner image is fixed on the sheet S, and thereafter, it is discharged to the outside of the apparatus main body 1 by a pair of upper and lower discharge rollers (conveying means) 5 and is stored in a discharge tray (next processing means) 6. Is configured. The sheets S are accumulated by size in a paper feed tray 7 arranged on the lower side in the apparatus main body 1, and a paper feed roller 8 provided for each paper feed tray 7 causes the photosensitive drum 2 and the transfer drum 3 to be separated. Be transported between. The conveyance direction of the sheet S from the transfer to the sheet discharge is set to the lateral direction.
The paper S is stored in the paper discharge tray 6 with the surface on which the image is formed facing upward.

FIG. 2 shows a portion after the fixing device 4. The fixing device 4 is composed of a combination of an upper heating roller 11 and a lower pressure roller 12. The surface of the heating roller 11 is heated to a predetermined temperature by a heating means (not shown) such as a built-in infrared lamp.
1, the pressure roller 12 is in contact with the pressure roller 12 by being pressurized with an appropriate pressure. Between the rollers 11 and 12, after the transfer process,
That is, the unfixed toner image is transferred onto the upper surface of the sheet S, and the unfixed toner image is heated and pressed onto the sheet S while the sheet S is fed to the left between the rollers 11 and 12. It has been established and fixed.

On the downstream side of the fixing device 4, the paper discharge roller 5 and the paper discharge tray 6 are arranged horizontally.
Further, between the fixing device 4 and the discharge roller 5, a chute (guide means) 2 for guiding the fixed sheet to the discharge roller 5 is provided.
1 is provided. The chute 21 is a pair of upper and lower chute plates 2 which are arranged parallel to each other at a predetermined distance.
2 is comprised. The sheet S sent out from the fixing device 4 enters the space between the chute plates 22 and is conveyed, so that the sheet S is positioned and guided with respect to the sheet discharge roller 5.

On the inner surface of the chute 21, that is, the inner surfaces of the upper and lower chute plates 22 facing each other, a water absorbing sheet made of, for example, felt, sponge, polymer absorbent or the like (first water droplet adhesion preventing means, water absorbing material) is formed. (Member) 31 is stretched. A similar water absorbing sheet (second water droplet adhesion preventing means, water absorbing member) 32 is also wound around the entire surface of the paper discharge roller 5. These water absorbing sheets 31,
The width of each of the sheets 32 is at least as large as the width of the sheet S to be conveyed and is provided.

B. The sheet S on which the toner image is fixed on the upper surface of the action fixing device 4 of the first embodiment is
While being conveyed in the chute 21 toward the paper discharge roller 5, the water contained in the sheet S before fixing is evaporated by being heated by the heating roller 11, and in the conventional case, each chute is evaporated. In some cases, the water may adhere to the inner surface of the plate 22 as dew condensation. However, in the present embodiment, the water evaporated from the paper S is absorbed by the water absorbing sheet 31, so that dew condensation does not occur and it does not face the paper S as water droplets. Therefore, adhesion of water droplets to both surfaces of the paper S passing through the chute 21 is suppressed, and as a result, the toner image on the paper S is prevented from being soiled or wrinkled, and the chute 21 is prevented.
Paper jamming inside is also prevented, and the paper S is smoothly accommodated in the paper discharge tray 6.

Further, depending on the water content of the paper S being relatively high, or depending on the operating environment such as temperature and humidity, it may be assumed that the water vapor evaporated from the paper S reaches the surface of the paper discharge roller 5 to cause dew condensation. However, in the present embodiment, since the water absorbing sheet 32 is also wound around the surface of the paper discharge roller 5, the adverse effect of dew condensation on the paper S passing through the paper discharge roller 5 does not occur.

C. Application Example to Other Types of Copiers FIGS. 1B and 1C are schematic views of a copier of a type different from that of FIG. The same components as those in FIG. 1A are designated by the same reference numerals, and the description thereof will be omitted.

C-1. Another type of copying machine: No. 1 In the copying machine of FIG. 1B, the conveying direction of the sheet S from sheet feeding to transfer to fixing is set to a vertically rising direction. The paper S that has passed through the fixing device 4 is stored in either the paper discharge tray 6 or another paper discharge tray (next processing means) 9 provided above the apparatus main body 1. The paper S is stored in the paper discharge tray 9 with its front side facing down. As shown in FIG. 3, on the downstream side of the fixing device 4, a chute 21 similar to the chute 21 is provided, and on the downstream side of the chute 21, the paper S is distributed to the left and right paper discharge trays 6 and 9. A gate (guide means) 51 is provided. The sheet S is guided to the right or left by the gate 51 to reach the paper ejection roller 5, and is accommodated in the paper ejection trays 6 and 9 from the paper ejection roller 5.

In this case, a water absorbing sheet 31 is stretched on the inner surface of the chute 21 and the contact surface of the gate 51 for the paper S as a first water drop adhesion preventing means, and the surface of the paper discharge roller 5 is
A water absorbing sheet 32 is stretched as a second water drop adhesion preventing means. Therefore, when the water evaporated from the sheet S that has passed through the fixing device 4 reaches the inner surface of the chute 21, the contact surface of the sheet 51 of the gate 51, and the surface of the paper discharge roller 5, the water is absorbed by the water absorbing sheets 31 and 32. Therefore, it can be prevented from adhering as water drops. Therefore, it is possible to prevent water droplets from adhering to both surfaces of the paper S that is conveyed while contacting the water absorbing sheets 31 and 32. As a result, the toner image on the paper S and the occurrence of paper wrinkles are suppressed, paper jamming is prevented, and the paper S is smoothly accommodated in the paper discharge trays 6 and 9.

C-2. Another type of copying machine No. 2 In addition to the copying machine of FIG. 1 (b), the copying machine of FIG.
A double-sided copying unit (next processing means) 61 for automatically performing double-sided copying is provided. The duplex copying unit 61
A gate (guide means) 62 for allocating the paper delivered from the left paper ejection roller 5 to either the paper ejection tray 6 side or the double-sided copying process, the paper ejection roller 5 on the front side of the paper ejection tray 6, and the surface copying. The upper and lower conveying rollers (conveying means) 63 for conveying the paper S which has been processed to the re-copying process. As shown in FIG. 4, the transport roller 63 is a motor 64.
The drive roller 64 rotated by A and the driven roller 65 that comes into contact with the drive roller 64 at an appropriate pressure are combined.

In the case of double-sided copying, first, the toner image is copied on the surface, that is, the sheet S that has passed through the fixing device 4 is
The sheet is once conveyed to the discharge tray 9 side by the gate 51, then switched back, and then conveyed into the double-sided copying unit 61 by the gate 51. Then, the toner image is transferred to the back surface by being guided downward by the gate 62 and passing again between the upper and lower conveying rollers 63 between the photosensitive drum 2 and the transfer drum 3, and then the fixing device 4 fixes the toner image. , The gate 51 distributes the paper to the left or right, and the paper discharge roller 5 stores the paper in one of the paper discharge trays 6 and 9. Further, in the case of copying only on the normal surface, the sheet S that has passed through the fixing device 4 is accommodated as it is from the sheet discharge roller 5 into one of the sheet discharge trays 6 and 9.

In this case, the water absorbing sheets 31 and 32 are stretched on the inner surface of the chute 21, the contact surface of the sheets S of the gates 51 and 62, and the surface of the sheet discharge roller 5 in the same manner as described above, and further, the conveying rollers. A water absorbing sheet 32 is also stretched on the surface of 63 as a second water drop adhesion preventing means. Therefore, the water vaporized from the sheet S that has passed through the fixing device 4 is absorbed by the sheet S on the inner surface of the chute 21 and the gates 51 and 62.
When it reaches the contact surface of, the surface of the paper discharge roller 5, and the surface of the transport roller 63, water is prevented from being absorbed by the water absorbing sheets 31 and 32 and adhering as water droplets. Therefore, the sheet S conveyed while contacting these water absorbing sheets 31, 32
Water droplets on both sides of the can be suppressed. As a result, the paper S
The occurrence of paper stains and paper wrinkles on the upper toner image is suppressed, paper jams are prevented, and the paper S is smoothly stored in the paper discharge trays 6 and 9.

(2) Second embodiment (water adhering to paper
Droplet Removal) In the above-described first embodiment, the water droplet adhesion preventing means is formed of a water absorbing sheet to prevent the water droplets from adhering to the paper. A second embodiment for removing and finally preventing water droplets from adhering to a sheet will be described. The following description is an example applied to the portion of the conveying roller 63 of the double-sided copying unit 61, but the applied portion is not limited to this, and can be applied anywhere along the paper conveying path.

A. Second Embodiment Part 1 (FIG. 5) Blades (second water droplet adhesion preventing means, water absorbing member) 71 whose both ends contact the paper S with a certain pressure on both sides of the paper S conveyed by the conveyance rollers 63 . Are provided facing each other. The blade 71 is made of a polymer absorption sheet (Mylar sheet) having appropriate elasticity, is fixed to the support member 72, and is arranged obliquely along the conveyance direction of the paper S. The blade 71 contacts the entire surface of the sheet S that is conveyed wider than the width of the sheet S. When dew condensation water drops adhere to one or both sides of the paper S, the water drops are quickly absorbed by the blade 71 as the paper S is conveyed.

B. Second Embodiment Part 2 (FIG. 6) The blades 71 are arranged so as to be vertically offset with respect to both sides of the paper S to be conveyed, and the blades 7 sandwich the paper S therebetween.
A chute plate 73 is arranged on the opposite side of 1. The conveyance direction of the sheet S is determined by passing between the blade 71 and the chute plate 73. Also in this case, when dew condensation water drops adhere to one side or both sides of the paper S, the water drops are quickly absorbed by the blade 71 as the paper S is conveyed.

C. Second Embodiment Part 3 (FIG. 7) Nozzles (air jetting members) 74 for jetting air R to the entire width of the sheet S are provided on both sides of the sheet S conveyed by the conveying rollers 63 so as to face each other. ing. The nozzles 74 are arranged obliquely in the transport direction of the paper S. When a water droplet of dewdrop adheres to one surface or both surfaces of the paper sheet S, the water droplet is quickly blown and removed by the air R ejected from the nozzle 74 as the paper sheet S is conveyed. In this case, since the nozzles 74 are arranged in the conveying direction of the sheet S, the ejection speed of the air R is relatively increased, which is effective.

D. Second Embodiment Part 4 (FIG. 8) The transport roller 63 is a heating member heated by a heating unit (not shown) . Therefore, the transport roller 6
The sheet S passing through the sheet 3 is heated. If dewdrops adhere to one or both sides of the paper S,
The water droplets are heated by contacting the transport roller 63,
The paper S is evaporated and the paper S is dried to remove water droplets.

E. Second Embodiment Part 5 (FIG. 9) A heater plate (heating member) 75 is provided on the upstream side of the conveying roller 63 so as to sandwich the conveyed paper S. The heater plates 75 are arranged as close as possible to both sides of the conveyed sheet S, and are heated by a heating means (not shown). The sheet S is heated and dried by passing between the heater plates 75, whereby the water droplets of dew condensation attached to the sheet S are removed.

(3) Modified Examples of the Present Invention and Other Application Examples The present invention is not limited to the configurations of the above-described embodiments, and the following modifications or applications are possible, for example. A means for preventing water droplets from adhering to members such as the chute 21 and the paper discharge roller 5 and a means for removing water droplets adhering to the paper S are used together. For example, the chute 21 is heated and a water absorbing sheet is wound around the surface of the paper discharge roller 5. Also shoot 2
It is also possible to heat the water absorbing sheet 31 so that the water absorbing sheet 31 is always kept in a dry state, thereby improving the water droplet absorbing action. As a means for preventing water droplets from adhering to members such as the chute 21 and the discharge roller 5, air is jetted or dried by heating in the manner of removing water droplets adhering to the paper S as described above. The present invention is not limited to the above copying machine, but can be applied to other image forming apparatuses using an electrophotographic process such as a printer and a facsimile.

[0028]

According to the present invention, when the water evaporated from the sheet passing through the fixing device is condensed on the guide means and the conveying means on the downstream side of the fixing apparatus, and the water droplets are attached before or when they are attached to the sheet. Since the adhesion of the water droplets on both sides of the paper is prevented by the first first water droplet adhesion prevention means and the second water droplet adhesion prevention means, the toner image on the paper is stained, paper wrinkles are generated, and the paper is jammed. Such problems can be almost completely prevented.

[Brief description of drawings]

1A, 1B, and 1C are schematic side views of a copying machine to which a first embodiment of the present invention is applied.

FIG. 2 is a side view showing a first application example of the first exemplary embodiment of the present invention.

FIG. 3 is a side view showing a second application example of the first embodiment.

FIG. 4 is a perspective view showing a third application example of the first embodiment.

FIG. 5 is a side view of the second preferred embodiment 1 of the present invention.

FIG. 6 is a side view of a second preferred embodiment 2 of the present invention.

FIG. 7 is a side view of a third preferred embodiment 3 of the present invention.

FIG. 8 is a side view of the fourth preferred embodiment 4 of the present invention.

FIG. 9 is a side view of the fifth preferred embodiment 5 of the present invention.

[Explanation of symbols]

4 ... Fixing device, 5 ... Paper discharge rollers (conveying means), 6, 9 ...
Paper discharge tray (next processing means), 21 ... Chute (guide means), 31 ... Water absorbing sheet (first water drop adhesion preventing means,
Water absorbing member), 32 ... Water absorbing sheet (second water drop adhesion preventing means, water absorbing member), 51, 62 ... Gate (guide means),
61 ... Duplex copying unit (next processing means), 63 ... Conveying roller (conveying means, heating member), 71 ... Blade (second)
Water drop adhesion preventing means, water absorbing member), 74 ... Nozzle (air jetting member), 75 ... Chute plate (heating member), S ... Paper.

Claims (4)

[Claims] 1. A fixing device for heating a sheet to fix an image on the sheet, guide means arranged opposite to both sides of the sheet fed from the fixing device, and receiving the sheet from the guide means, Conveying means for conveying the paper to the next processing means, first water drop adhesion preventing means for preventing adhesion of water drops on both sides of the paper passing through the guide means, and both sides of the paper passing through the conveying means An image forming apparatus comprising: a second water drop adhesion preventing unit that prevents water drops from adhering to the image forming apparatus. 2. The image forming apparatus according to claim 1, wherein the water drop adhesion preventing unit is a water absorbing member that absorbs water drops. 3. The image forming apparatus according to claim 1, wherein the water drop adhesion preventing unit is an air ejecting member that blows away the water drops by air. 4. The image forming apparatus according to claim 1, wherein the water droplet adhesion preventing unit is a heating member.