JPH11153919A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten processing time without exerting adverse effect on an image and to miniaturize the device by constituting the surface of a guide plate guiding the carrying direction of an output medium of a continuous smooth surface coming in surface-contact with the image surface of the output medium. SOLUTION: Two guide plates 67a and 67b are arranged to be opposed to each other on the downstream side of a driving roller 63 and a carrying roller 65 in a paper ejection part 61. At least the areas of the surfaces of the plates 67a and 67b, having possibility of coming in contact with recording paper, desirably, all the surfaces thereof are constituted of the even continuous smooth surface coming in surface-contact with the image surface of the recording paper. Since the image surface of the recording paper comes in surface-contact with the surfaces of the plates 67a and 67b, contact resistance is not concentrated at the limited part of the image surface and is dispersed, whereby the peeling or the soiling of the image hardly occurs. Therefore, what is called a straight part need not be provided for the purpose of cooling after thermal fixing, because the recording paper is carried in a high-temperature state while changing its direction in a state where it is brought into contact with the plates 67a and 67b in the paper ejection part.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an image forming apparatus for fixing an image by heat.

[0002]

2. Description of the Related Art In a PPC copying machine (Plain Paper Copy) or the like, in order to fix toner after transferring an image, a recording paper is pressed at a high temperature by a fixing roller and a pressure roller set at a predetermined temperature, and thereafter recording is performed. The paper has been ejected. The recording paper immediately after fixing has a high temperature higher than the toner melting temperature, and the fixing is not stable. For this reason, if the surface of the recording paper on which the image is formed (hereinafter, referred to as “image surface”) comes into contact with any member and is rubbed, the toner adheres to the member and the image peels off or stains occur. I do.

[0003] In particular, in a paper discharge section for discharging recording paper to a paper discharge tray, there is provided a guide plate for guiding the recording paper in the conveying direction. The guide plate has a rib-like structure provided with a convex portion or a slit provided at a predetermined interval in order to reduce the contact resistance with the recording paper. For this reason, when the high-temperature recording paper comes into partial contact with the guide plate, the contact resistance is concentrated on the contact portion, and the image is easily peeled.

Conventionally, as shown in FIG. 5, in an image forming apparatus 111, an image is formed on a recording sheet supplied from a sheet feeding section 113 by an image forming section 115, and then an image is formed by a heat fixing section 117. To establish. Thereafter, the recording paper is cooled to some extent by conveying the high-temperature recording paper while keeping it horizontal, in a straight portion 119 provided on the downstream side of the heat fixing section 117. Next, the recording paper is turned by the guide plate 125 in the paper discharge unit 121 and discharged to the tray 123. At this time, since the recording paper has been cooled to a temperature lower than the melting temperature of the toner, even if the recording paper comes into contact with the guide plate 125, the image will not be peeled off or stained.

[0005]

However, when the recording paper is cooled by providing the straight portion 119 and then discharged from the paper discharge portion 121, the time required for image forming processing such as copying is extended due to an increase in the transport distance. Also, the image forming apparatus 111
The whole becomes larger.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an image forming apparatus which can shorten the processing time and easily reduce the size without adversely affecting an image.

[0007]

According to one aspect of the present invention, there is provided an image forming section for forming an image on a surface of an output medium, and heat fixing the image by heating the output medium. An image forming apparatus comprising: a heat fixing unit that performs heat fixing; and a conveyance unit that conveys the output medium after the heat fixing, wherein the conveyance unit has a guide plate that guides a conveyance direction of the output medium, and the guide plate Is a continuous smooth surface which is in surface contact with the image surface of the output medium.

According to the first aspect of the present invention, since the image surface of the output medium kept at a high temperature is in surface contact with the surface of the guide plate formed of a continuous smooth surface having no irregularities, the contact resistance is reduced locally on the image surface. Instead of being concentrated, it is distributed. Thus, even if the distance between the heat fixing unit and the conveying unit is shortened and the output medium reaches the guide plate at a high temperature, peeling of the image and generation of stains are unlikely to occur.

According to a second aspect of the present invention, there is provided an image forming section for forming an image on the surface of an output medium, a heat fixing section for heating the output medium to thermally fix the image, and transporting the output medium after the heat fixing. And a transport unit, wherein the transport unit has a guide plate for guiding the transport direction of the output medium, and a transport roller that rotates on the surface of the guide plate by contact with the output medium. Is provided.

According to the second aspect of the present invention, the output medium kept at a high temperature is guided in the transport direction while contacting the transport rollers. However, the transport rollers do not rub the image surface, so that the fixing is still stable. There is almost no possibility that an unimaged image will adhere to the transport rollers. With this, even if the output medium reaches the guide plate at a high temperature by shortening the distance between the heat fixing unit and the conveying unit,
Image peeling and stains are unlikely to occur.

According to a third aspect of the present invention, there is provided an image forming section for forming an image on the surface of an output medium, a heat fixing section for heating the output medium to thermally fix the image, and transporting the output medium after the heat fixing. The image forming unit, the heat fixing unit and the transport unit are vertically arranged, and the transport unit includes a guide plate that guides the transport direction of the output medium. Wherein the surface of the guide plate is constituted by a continuous smooth surface which is in surface contact with the image surface of the output medium.

According to the third aspect of the present invention, since the image forming section, the heat fixing section and the transport section are arranged vertically, the transport distance of the output medium is shortened, and the entire apparatus is compact. become. As the conveyance distance of the output medium after the heat fixing is shortened, the output medium reaches the conveyance section at a high temperature, but its image surface is in surface contact with the surface of the guide plate formed of a continuous smooth surface without irregularities. Therefore, the contact resistance is not concentrated on a local portion of the image plane, but is dispersed. Therefore, peeling of images and generation of stains are unlikely to occur.

According to a fourth aspect of the present invention, there is provided an image forming section for forming an image on the surface of an output medium, a heat fixing section for heating the output medium to thermally fix the image, and transporting the output medium after the heat fixing. The image forming unit, the heat fixing unit and the conveying unit are vertically arranged, the conveying unit has a guide plate for guiding the conveying direction of the output medium. A conveying roller that rotates on contact with the output medium on a surface of the guide plate.

According to the fourth aspect of the present invention, since the image forming section, the heat fixing section and the transport section are arranged vertically, the transport distance of the output medium is shortened, and the entire apparatus is compact. become. As the transport distance of the output medium after thermal fixing is shortened, the output medium reaches the transport section at a high temperature.However, the transport rollers do not rub the image surface, so the image whose fixing has not yet been stabilized is transferred to the transport rollers. There is almost no risk of adhesion. Therefore, peeling of images and generation of stains are unlikely to occur.

[0015]

Embodiments of the present invention will be described below in detail with reference to FIGS.

FIG. 1 is a schematic diagram showing an image forming apparatus according to a first embodiment of the present invention.

The image forming apparatus 11 has a sheet feeding section 13 at the bottom.
Is provided. The paper feed unit 13 is a cassette 1 that stores recording paper 15 such as plain paper or OHP sheet as an output medium.
7 and a paper feed mechanism 19 provided for each of them,
The recording paper 15 is sent out to the paper feed path 21, and is transported upward by a pair of transport rollers 23 provided at various parts of the paper feed path 21.

Above the paper supply unit 13, a transfer unit 31, a heat fixing unit 51, and a paper discharge unit 61 are sequentially arranged in a substantially vertical direction. The transfer unit 31 has a photosensitive drum 33, and a charging device 35, an exposure device 37, a developing device 39,
The static elimination device 41 and the cleaning device 43 are arranged. Further, a pressure belt 45 is provided so as to be in contact with the photosensitive drum 33.

The heat fixing section 51 has a fixing roller 53 and a pressure roller 55. The fixing roller 53 is set at a predetermined temperature (for example, 185 ° C.) by a heating unit (not shown).

As shown in FIG. 2, the paper discharge section 61 has a drive roller 63 provided immediately above the heat fixing section 51 and a transport roller 65 which rotates in contact with the drive roller 63. Downstream of the drive roller 63 and the transport roller 65, two guide plates 67
a and 67b are arranged facing each other. These guide plates 67a and 67b are curved so as to change the conveying direction of the recording paper 15 from a vertical direction to a horizontal direction.

At least a region, preferably the entire surface, of the surfaces of the guide plates 67a and 67b which may come into contact with the recording paper 15, is preferably a smooth surface without any irregularities which is in surface contact with the image surface of the recording paper 15 ( Hereinafter, it is referred to as “continuous smooth surface”).

Further, on the downstream side of the guide plates 67a and 67b, a drive roller 69 and a discharge roller 71 which rotates in contact with the drive roller 69 are arranged. A tray 73 is provided on the discharge side of the drive roller 69 and the discharge roller 71.

A double-sided unit 81 is provided on the side of the transfer unit 31 and the heat fixing unit 51. In the double-sided unit 81, the claw-shaped first direction switching member 83 provided between the heat fixing unit 51 and the sheet discharging unit 61 is operated to introduce the recording paper 15 after the heat fixing into the double-sided unit 81. The pair 85 is primarily stored in the recording paper storage unit 87. Next, the rotation of the pair of reversing rollers 85 is reversed, and the recording paper 15 is sent out from the recording paper storage part 87, and the second direction switching member 89
Is operated to introduce the recording paper 15 into the return path 91. The recording paper 15 is conveyed by pairs of conveying rollers 93 and 95 provided at various portions of the return path 91 and returned to the transfer unit 31. Therefore,
The recording paper 15 on which an image is formed on the front surface is
To supply it to the transfer unit 31 again, and form an image on the back surface.

Next, the operation of the image forming apparatus 11 will be described. First, the recording paper 15 is sent from the paper supply unit 13 to the transfer unit 31. In the transfer unit 31, the recording paper 15 is pressed between the photosensitive drum 33 and the pressure belt 45, and the recording paper 15 is pressed.
The toner image formed on the peripheral surface of the photosensitive drum 33 is transferred to the surface of the photosensitive drum 33 to form an image. Next, in the heat fixing unit 51,
The recording paper 15 is pressed at a high temperature by the fixing roller 53 and the pressure roller 55 to thermally fix the image.

Next, the recording paper 15 after the heat fixing is turned over by the double-sided unit 81, and the processing is sequentially performed again by the transfer unit 31 and the heat fixing unit 51 to form an image on the rear surface and fix it.
The temperature of the recording paper 15 after the heat fixing is equal to or higher than the melting temperature of the toner. Although the melting temperature of the toner varies depending on the type of the toner, it was 85 ° C. in this example. In this way, the recording paper 15 after the heat fixing is fed to the paper discharge unit 61 at the high temperature.

In the paper discharging section 61, the recording paper 15 is inserted between the driving roller 63 and the conveying roller 65, and is sent out to the guide plates 67a and 67b by the rotation thereof. The recording paper 15 is changed from vertical to horizontal by contacting the guide plates 67a and 67b, and the driving roller 69 and the discharge roller 7
Insert between 1. Then, the recording paper 15 is discharged by the rotation of the drive roller 69 and the paper discharge roller 71, and received by the tray 73.

Here, since the surfaces of the guide plates 67a and 67b are formed as continuous smooth surfaces, the image surface of the recording paper 15 is in surface contact with the surfaces of the guide plates 67a and 67b. As a result, the contact resistance is not concentrated on a local portion of the image surface, but is dispersed.
Image peeling and stains are unlikely to occur. Therefore, the recording paper 15 can be conveyed at a high temperature while changing the direction by contacting the guide plates 67a and 67b with the paper discharge unit 51, so that there is no need to provide a so-called straight part for cooling after the heat fixing. As a result, the distance from the heat fixing unit 51 to the paper discharge unit 61 can be reduced, the apparatus can be downsized, and the time from start to paper discharge can be reduced.

Further, since there is no need to provide a straight section, the layout of each section of the image forming apparatus 11 becomes free, and the transport distance of the recording paper can be shortened and the apparatus can be more easily downsized. For example, as in this embodiment, the transfer section 31, the fixing section 51, and the paper discharge section 61 can be arranged substantially vertically. This arrangement is not possible when a straight portion is provided.

The guide plates 67a and 67b may be formed of a resin molded product or a sheet metal coated with resin.
This is preferable because the contact resistance with the metal becomes low.

In this embodiment, the guide plate 67
Although both surfaces a and 67b are constituted by continuous smooth surfaces, when an image is formed on only one surface, it is sufficient to constitute only one of them with a continuous smooth surface.

Next, an image forming apparatus according to a second embodiment of the present invention will be described with reference to FIG. The paper discharge unit 101 of the image forming apparatus according to this embodiment includes a guide plate 103.
a, the outer one of the guide plates 103a is
It has a projection 105 on the surface and a plurality of transport rollers 10
The configuration is the same as that of the first embodiment except that 7 is attached. More specifically, as shown in FIG. 4, on the surface of the guide plate 103a, a plurality of protrusions 105 are formed at predetermined intervals along the transport direction of the recording paper 15. Also,
The conveying roller 107, which is an integrally molded product of resin,
Each of them is rotatably fitted in a concave portion 109 formed in 03a.

In the image forming apparatus provided with the paper discharge unit 101 having the above-described configuration, the transport roller 107 is provided on the guide plate 103a. Is changed from the vertical direction to the horizontal direction. However, since the transport roller 107 does not rub the image surface, there is almost no possibility that an image whose fixing has not been stabilized yet adheres to the transport roller 107. Therefore, peeling of images and generation of stains are unlikely to occur. As a result, there is no need to provide a so-called straight section for cooling after the heat fixing, so that the distance from the heat fixing section 51 to the sheet discharging section 61 can be shortened, the apparatus can be downsized, and the time from start to sheet discharging can be reduced. Can be shortened.
Further, since there is no need to provide a straight section, the layout of each section of the image forming apparatus 101 becomes free, and the conveyance distance of the recording paper and the size of the apparatus can be further easily reduced.

In this embodiment, the transport rollers 107 are
Although provided on only one guide plate 103a, it may be provided on the other guide plate 103b. Also, the guide plate 10
By configuring the surface of 3a as a continuous smooth surface as in the first embodiment, the action of both the continuous smooth surface and the transport roller 107 can further suppress the occurrence of image peeling and dirt.

The present invention is not limited to the above-described embodiment, and various changes can be made without departing from the gist of the present invention. In the first and second embodiments, a double-sided image forming apparatus has been described as an example, but a single-sided image forming apparatus may be used. In this case, it suffices if the guide plate corresponding to the image surface is formed of a continuous smooth surface, or if a transport roller is provided. Further, as the transport unit, the paper discharge units 61 and 101 for finally discharging the recording paper 15 have been described as an example. However, the present invention is not particularly limited to this, and the transport unit that transports the recording paper 15 after heat fixing is used. In particular, any method may be used as long as it involves changing the direction of conveyance of the recording paper 15 by the guide plate. Also, the present invention
The present invention is applicable to all image forming apparatuses such as a copying machine, a facsimile, and a printer.

[0035]

As described above, according to the first aspect of the present invention, even if the output medium reaches the guide plate at a high temperature by shortening the distance between the heat fixing unit and the conveying unit, the guide plate can be used. Since the surface is formed of a continuous smooth surface, peeling of images and generation of stains are unlikely to occur, so that the processing time can be reduced and the size of the apparatus can be reduced.

According to the second aspect of the present invention, even if the distance between the heat fixing unit and the conveying unit is shortened and the output medium reaches the guide plate at a high temperature, the conveying rollers are provided on the surface of the guide plate. Therefore, image peeling and dirt hardly occur, so that image peeling and dirt hardly occur, so that the processing time can be reduced and the size of the apparatus can be reduced.

According to the third aspect of the present invention, the transport distance of the output medium is shortened, and the entire apparatus is reduced in size.
Even if the conveyance distance of the output medium after the heat fixing is shortened, the image is unlikely to be peeled or stained, so that the processing time can be reduced and the apparatus can be reduced in size.

According to the fourth aspect of the present invention, since the image forming section, the heat fixing section, and the transport section are arranged in the vertical direction, the transport distance of the output medium is shortened, and the entire apparatus is reduced in size. Also, even if the conveyance distance of the output medium after the heat fixing is shortened, the image is hardly peeled off or stained, so that the processing time and the size of the apparatus can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic diagram illustrating an image forming apparatus according to a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a paper discharge unit of the image forming apparatus shown in FIG.

FIG. 3 is a schematic diagram illustrating a paper discharge unit of an image forming apparatus according to a second embodiment of the present disclosure.

FIG. 4 is a perspective view showing a part of a guide plate of the paper discharge unit shown in FIG. 3;

FIG. 5 is a schematic diagram illustrating a conventional image forming apparatus.

[Explanation of symbols]

 REFERENCE SIGNS LIST 11 image forming apparatus 13 paper feed unit 15 recording paper 31 transfer unit 51 heat fixing unit 61 paper discharge units 67a, 67b guide plate 81 duplex unit 101 paper discharge units 103a, 103b guide plate 107 transport roller

Claims (4)

[Claims] An image forming section for forming an image on a surface of an output medium, a heat fixing section for heating the output medium to thermally fix the image, and a conveying section for conveying the output medium after the heat fixing. In the image forming apparatus, the transport unit may include a guide plate that guides a transport direction of the output medium, and a surface of the guide plate may be configured as a continuous smooth surface that is in surface contact with an image surface of the output medium. Characteristic image forming apparatus. 2. An image forming section for forming an image on the surface of an output medium, a heat fixing section for heating the output medium and thermally fixing the image, and a transport section for transporting the output medium after the thermal fixing. In the image forming apparatus, the transport unit has a guide plate that guides a transport direction of the output medium, and a transport roller that rotates on contact with the output medium is provided on a surface of the guide plate. Image forming apparatus. 3. An image forming section for forming an image on the surface of an output medium, a heat fixing section for heating the output medium and thermally fixing the image, and a transport section for transporting the output medium after the thermal fixing. In the image forming apparatus, the image forming unit, the heat fixing unit and the transport unit are vertically arranged, the transport unit has a guide plate for guiding a transport direction of the output medium, An image forming apparatus, wherein the surface is constituted by a continuous smooth surface which is in surface contact with the image surface of the output medium. 4. An image forming section for forming an image on the surface of an output medium, a heat fixing section for heating the output medium to thermally fix the image, and a conveying section for conveying the output medium after the heat fixing. In the image forming apparatus, the image forming unit, the heat fixing unit and the transport unit are arranged in a vertical direction, the transport unit has a guide plate for guiding the transport direction of the output medium, and a surface of the guide plate An image forming apparatus, comprising: a conveying roller that rotates upon contact with the output medium.