JP2001122490A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small-sized image forming device involving no time loss even in the case image forming is made on a number of recording sheets continuously and capable of blowing in a constant air quantity without performing an air quantity adjustment. SOLUTION: The image forming device is typically equipped with a discharge roller 21 to discharge a recording medium P in sheet form for recording images, a discharge tray 22 which is installed under the discharge roller 21 and whereon recording sheets P are stacked, and a blowing means 23 to send air to that surface of tray 22 where the sheets P are stacked, wherein the blowout hole 27 of the blowing means 23 is positioned at a level between the nip of the discharge roller 21 and the maximum stacking height 29 of the discharge tray 22.

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 capable of suitably discharging and stacking recording media even when images are continuously formed on a large number of recording media.

[0002]

2. Description of the Related Art A conventional image forming apparatus will be described with reference to the drawings. FIG. 8 is an explanatory diagram of a discharge unit of an image forming apparatus according to a conventional example, and FIG. 9 is an explanatory diagram of a blowing unit according to a conventional example.

Various image forming apparatuses have been manufactured and sold so far. However, user requirements change daily,
It is also diversifying. Above all, there is a particularly high demand for downsizing and productivity improvement of the image forming apparatus, and at the same time, it has become indispensable to form a full-color image and to cope with various recording media.

[0004] In a conventional image forming apparatus, particularly an electrophotographic image forming apparatus for forming a full-color image, forming an image on a relatively thick recording medium or an OHT film has many problems. In reality, it is not easy to meet such demands at a high level.

[0005] Thick recording media and recording media such as OHT films require more heat during fixing than ordinary recording media. In particular, in the case of the OHT film, when the amount of heat is small, not only does the fixing property of the toner deteriorate, but also the problem that the transparency of the toner when projected by a projector is low occurs. Therefore, when an image is formed on them, there is a method in which the conveying speed in the fixing device is set to be lower than the process speed at the time of normal image forming, and the amount of heat is compensated by taking time.

[0006] In such an electrophotographic full-color image forming apparatus, a plurality of recording media are stacked on a discharge tray depending on the environment in which the image forming apparatus is placed, such as forming an image with a large amount of toner deposition. In this case, a problem may occur that the recording media adhere to each other due to fusion of the toner.

Particularly, when an image is formed on a thick recording medium or an OHT film, since the surface temperature is high, if the toner is supposed to be discharged and stacked one after another, the toner fixed on the surface is fused. In some cases, thick recording media or OHT films that are attached and stacked may adhere to each other.

Further, when a large amount of heat is applied to the OHT film, the stiffness of the OHT film becomes weak, and when the OHT film is discharged to the discharge tray by the discharge roller, the OHT film starts from the moment when the leading end of the OHT film comes out of the nip of the discharge roller. It is discharged in a state that it hangs down. For this reason, there is often a problem that the quality is extremely deteriorated because the sheet is not suitably loaded on the discharge tray, or is cooled down by the outside air and solidified in a rounded shape.

In order to solve the above-mentioned problems, in the conventional image forming apparatus, for example, with respect to the adhesion of the recording medium, the distance from the fixing device to the discharge tray is sufficiently provided, and a cooling means or the like is provided therebetween to set the temperature of the recording medium. Some take measures to lower In addition, there is also a method in which an image is formed on the next recording medium after a sufficient time for simply lowering the temperature of the recording medium. In addition, for the problem that the OHT film becomes weak and hardened in a rounded shape, in addition to the cooling means, the transport speed is increased from the fixing to the discharge tray to a speed at which it can be discharged appropriately. There is.

[0010] However, although all of the measures are effective means in terms of suitably discharging and stacking, they are larger than desired in terms of miniaturization of the image forming apparatus.

Therefore, as shown in FIGS.
The provision of the air blowing means 103 in the image forming apparatus 10 satisfies the demand for miniaturization and improves the above-mentioned problems.
There is one. Hereinafter, the image forming apparatus 101 will be described.

The discharge unit 102 of the image forming apparatus 101 is
The blower 103 has a suction port 104, a multi-blade fan 105, a duct 106, and a blower port 107. The air outlet 107 extends from the lower portion of the discharge roller 108 to the vicinity of the loading surface of the discharge tray 109. With this configuration, the opening area of the air outlet 107 can be increased, so that the load on the multi-blade fan 105 that sends out air can be reduced, and the discharge and description of the recording medium P can be suitably performed for a relatively small number of image formation. it can.

The operation of discharging the recording medium in the discharge section 102 will be described with reference to FIG. First, after the leading end of the recording medium P comes out of the nip of the discharge roller 108, the recording medium P is given buoyancy by the air sent from the air blowing port 107 so that the leading end does not drop downward, and is lifted to a certain distance. The discharge can be continued in the state of being set (see FIG. 9A).

Therefore, the leading end of the recording medium P being discharged comes into contact with the discharge tray 109 or the leading end of the recording medium loaded in the discharging tray 109 in the discharge direction, and the surfaces of the recording medium do not slide. To reduce. When a recording medium is already loaded on the discharge tray 109, the toner surface is simultaneously cooled.

Next, the trailing end of the recording medium P is
Immediately before being discharged from the nip, the multi-blade fan 105 is stopped until the trailing end of the recording medium P falls on the discharge tray 109 or the recording medium loaded on the discharge tray 109.
Is not operated (see FIG. 9B).

Then, the trailing end of the recording medium P is
9 or after dropping on the recording medium loaded thereon, the multi-blade fan 105 is operated again to cool the image-formed toner surface of the recording medium P loaded on the discharge tray 109 (FIG. 9C). reference).

Incidentally, in such an image forming apparatus 101, the blowing means 103 only feeds a thick recording medium or an OHT film.
There is a control that uses the air blower 103 and a control that determines whether to use the air blower 103 based on image information to be formed. However, the air blower 103 is not used in a normal recording medium.

[0018]

However, in the above-described conventional image forming apparatus, when forming images on a large number of recording media continuously, image formation is delayed by the time required to stop the blower. In addition, the air blown out from the lower part of the air blower lifts the rear end of the recording medium, causing curling of the recording medium, and making it difficult for the air to flow on the surface of the recording medium to reduce cooling efficiency. Has to be done carefully.

Accordingly, the present invention provides a miniaturized image forming apparatus capable of blowing air at a constant air volume without adjusting the air volume without any time loss even when an image is continuously formed on a large number of recording media. It is intended to provide a device.

[0020]

In order to solve the above-mentioned problems, a typical configuration of an image forming apparatus according to the present invention comprises a discharge roller for discharging a recording medium for recording an image, and a discharge roller disposed below the discharge roller. A discharge tray on which the recording medium is loaded, and blowing means for sending air to a loading surface of the discharge tray on which the recording medium is loaded, wherein a blowing port of the blowing means is provided between the nip of the discharge roller and the discharge tray. It is characterized by being provided between the maximum loading heights.

[0021]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] A first embodiment of an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a configuration diagram of an image forming apparatus according to the first embodiment,
FIG. 2 is a perspective view of the image forming apparatus, FIG. 3 is an explanatory view of the blowing means, FIG. 4 is an explanatory view of the blowing means, and FIG. 5 is a perspective view of the image forming apparatus.

The image forming apparatus 1 according to the present embodiment is called a medium-to-low speed machine, and corresponds to an ordinary recording medium weighing about 60 to 200 g and an OHT film. In the case of a normal recording medium, about 20 sheets are formed per minute while being conveyed at a conveyance speed of about 100 mm / sec. In addition, weighing about 10
In the case of a thick recording medium of 0 g or more, the process speed is reduced to about half to form an image, and in the case of an OHT film, the process speed is reduced to about 1/4 to perform image formation.

As shown in FIG. 1, the image forming apparatus 1 includes a feeding unit 2, a conveying unit 3, an image forming unit 4, a fixing unit 5, and a discharging unit 6.
Consists of

In the feeding section 2, the recording medium P is stacked on the manual feed tray 7 and the feeding cassette 8, and is selectively fed to the transport section 3. When the paper is fed from the manual feed tray 7, the feeding is started by the pickup roller 9 and the separation claw is started.
The sheets are separated one by one by 10 and fed to a registration roller pair 12 by a feeding roller 11. Then, the skew of the recording sheet P is corrected by the registration roller pair 12 and the photosensitive drum 15
Is fed to the transport unit 3 so as to synchronize with.

The recording medium P fed to the transport section 3 is placed on a transport belt 14 wound around transport rollers 13 and passes through the image forming section 4 to the fixing section 5 on the downstream side in the transport direction. Conveyed.

In the image forming section 4, a light source device is provided on the outer peripheral surface of the electrophotographic photosensitive drum 15, which is an image bearing member, in accordance with an electric signal of image information transmitted from a reader scanner, a personal computer or the like (not shown). An electrostatic latent image is sequentially exposed by an LED (light emitting diode) 16. The electrostatic latent image is visualized by the developing device 17 to form a toner image. Then, the recording sheet P conveyed through the image forming unit 4
Are sequentially transferred the toner images formed on the photosensitive drum 15,
The sheet is conveyed to the fixing unit 5. On the other hand, the electrophotographic photosensitive drum 15 is scraped off the toner remaining on the photosensitive drum 15 by a cleaning device 18 provided in contact with the photosensitive drum 15 to prepare for the next image formation.

In the fixing section 5, the recording sheet P is heated by a heater.
The toner image is fixed on the recording sheet P by heating by 19 and pressing by the fixing roller pair 20. Thereafter, the recording sheet P is sent to the discharge unit 6.

As shown in FIGS. 1 to 3, the discharge section 6
It has a discharge roller 21, a discharge tray 22, and a blowing means 23, and the blowing means 23 has a suction port 24, a multi-blade fan 25, a duct 26, a blowing port 27.
Consists of The discharge roller 21 is provided at a position very close to about 30 mm from the fixing roller pair 20 in order to reduce the size of the image forming apparatus 1.

The multi-blade fan 25 is provided directly below the fixing unit 5, and receives air from a suction port 24 provided directly below the discharge tray 22.
(Outside air) is sucked. Then, the air is sent out from the air outlet 27 through a duct 26 which is an air passage. The air outlet 27 is a discharge roller
The discharge tray 21 is provided between the nip of the discharge roller 21 and the lowermost portion of the discharge roller 21 and is configured to send air to a loading surface of the discharge tray 22 on which a recording medium is loaded.

In the above configuration, the air blowing means is used until the leading end of the recording medium P sent to the discharge section 6 comes out of the nip.
23 operates to send air out of the air outlet 27. The amount of air blown out from the air outlet 27 is equal to the volume of all recording media P
Is discharged, and the flow rate is not adjusted until the series of image formation is completed, and is kept substantially constant.

After the tip comes out of the nip, the recording medium P
Is given a buoyancy by the air blown out from the blower port 27 so as not to hang down, and is discharged in a state of being lifted until the rear end comes out of the nip (see FIG. 4A). For this reason, the leading end of the recording medium P being discharged comes into contact with the discharge tray 22 or the leading end in the discharge direction of the recording medium stacked thereon, and the surfaces of the recording medium do not slide, thereby reducing sliding friction resistance. . In addition, when there is a recording medium already discharged on the discharge tray 22, the recording medium is also cooled.

When the rear end comes out of the nip, the air blown out from the air blow-out port 27 is substantially discharged because the air blow-out port 27 is provided between the nip of the discharge roller 21 and the lowermost part of the discharge roller 21. It flows toward the discharge tray 22 at a height between the nip of the roller 21 and the lowermost part of the discharge roller 21. The rear end of the recording medium P is dropped vertically below the flow of air by the rotational force of the discharge roller 21 (see FIG. 4B). Thereafter, the recording medium P is stacked on the discharge tray 22, and is cooled by blowing the toner surface on which the image has been formed.
(See FIG. 4C).

By forming the air blowing port 27 as described above, it is not necessary to stop the air blowing means 23 even when images are continuously formed on a large number of recording media, and time loss can be eliminated.

Further, since the sent air does not raise the rear end of the recording medium, the recording medium does not curl or the cooling efficiency does not decrease, the air is blown at a constant air volume without adjusting the air volume. I can do it.

As shown in FIG. 5, the discharge tray 22 may have a structure in which wind direction guides 28 are provided on both sides. This suppresses the diffusion of the air sent from the air outlet 27,
It is possible to reliably form a flow of air and to reliably apply buoyancy to the recording medium P, and to effectively cool the leading end of the recording medium P. By effectively utilizing the flow of air, the multi-blade fan 25 can have a low air volume. Therefore, by attaching the wind direction guide 28, it is possible to discharge and stack the recording medium P in a suitable manner.

In the above embodiment, the multi-blade fan
Although the outside air is sucked using 25, the air inside the image forming apparatus may be sucked and used together with the waste heat of the image forming apparatus 1. However, since it is more effective to cool the recording medium P when the temperature of the air to be sucked is lower, it is preferable to suck the air outside the image forming apparatus 1. In addition, blowing means 23
Although the multi-blade fan 25 is used, the type of the fan is not particularly limited.

[Second Embodiment] Next, a second embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 6 is an explanatory view of a discharge unit of the image forming apparatus according to the second embodiment, and a portion having the same function as the first embodiment is described.
The same reference numerals are given and the description is omitted.

In the first embodiment, the blowing port 27 is
Is provided between the nip of the discharge roller 21 and the lowermost portion of the discharge roller 21, but in the present embodiment, the nip of the discharge roller 21 and the discharge tray 21 are provided.
It is provided between 22 maximum loading heights 29. And FIG.
As shown in FIG. 7, the discharge unit 6 has a discharge roller 21 that rotates quickly and has a large force to drop the recording medium P downward in the vertical direction, and air is blown from a blower port 27 to a loading surface of the discharge tray 22 on which the recording medium is loaded. Is sent out.

In the above configuration, when the trailing end of the recording medium P sent to the discharge section 6 comes out of the nip, the blower port 27 is provided between the nip of the discharge roller 21 and the maximum stacking height 29 of the discharge tray 22. As a result, the air sent from the blower port 27 flows toward the discharge tray 22 at a height substantially between the nip of the discharge roller 21 and the maximum stacking height 29 of the discharge tray 22. Since the rotational force of the discharge roller 21 is large, the rear end of the recording medium P is dropped vertically downward from the flow of air sent from the air outlet 27 (see FIG. 4B). Thereafter, the recording medium P is stacked on the discharge tray 22, and is cooled by blowing the toner surface on which the image has been formed (see FIG. 4C).

By configuring the air outlet 27 and the discharge portion 6 as described above, the recording medium can be curled or the cooling efficiency can be reduced without the blown air lifting the rear end of the recording medium. Absent. Therefore, the air can be blown at a constant air volume without the necessity of adjusting the air volume or stopping the air blowing means, and the loss of time can be eliminated even when image formation is continuously performed on a large number of recording media.

Furthermore, by increasing the area of the air outlet 27 as compared with the first embodiment, the air volume is increased and the buoyancy is increased. For this reason, the cooling effect can be improved, and even a large recording medium can be suitably transported and stacked.

Although the discharge roller 21 has a high rotation speed, the force of dropping the recording medium P downward in the vertical direction is great, and it is sufficient if the recording medium P can be surely dropped. May be used.

[Third Embodiment] Next, a third embodiment of the image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 7 is an explanatory diagram of a blowing unit of the image forming apparatus according to the third embodiment. Portions having the same functions as those of the first embodiment and the second embodiment are denoted by the same reference numerals and description thereof is omitted.

The most suitable arrangement of the air outlets in the width direction of the recording medium (the direction of arrow A) is largely determined by the setting of the image forming apparatus and the material of the recording medium, but the size of the recording medium is also determined in determining the optimal arrangement. It is an important factor.

In this embodiment, as shown in FIG.
The air outlet 27 is provided evenly in the width of about 70% (210 mm) of the recording medium left and right about the center 30 in the conveyance direction of the image forming apparatus 1. They were arranged in two stages. With this arrangement, the amount of air blown out by the air blowing means tends to decrease from the center in the width direction of the recording medium toward both sides. Thereby, the buoyancy can be most effectively applied to the recording medium P, and the buoyancy can be effectively obtained for a recording medium having a large size in the depth direction as large as 300 mm even when the air volume is slightly weak.

It should be noted that the numerical values used here are an example of the setting and are not limited thereto, and any setting may be used as long as the setting allows the buoyancy to be effectively applied to the recording medium P. In addition, for a recording medium having a small size in the depth direction, there is no problem even if the air outlets are arranged uniformly over the entire area.

With the above arrangement, there is no problem even if the image forming apparatus 1 according to the present embodiment is a center reference image forming apparatus that uniformly conveys all the corresponding recording media to the center of the conveying area. On the other hand, in a one-sided reference image forming apparatus that conveys a recording medium such that one side is at the same position,
The same effect can be obtained by arranging the air outlets such that the air volume gradually decreases toward both sides with the peak at the position where the center of the recording medium is concentrated.

Although the air volume is regulated by the arrangement of the air vent 27 here, the air volume may be regulated or adjusted by using a duct or a plurality of fans.

The image forming apparatus according to the present invention may be an ink-jet type image forming apparatus having no fixing device, and can be used for drying an image-formed ink on the surface of the recording medium P.

[0050]

As described above, the blowing port of the blowing means is provided between the nip of the discharging roller and the lowermost portion of the discharging roller, or between the nip of the discharging roller and the maximum stacking height of the discharging tray. Accordingly, the sent air does not raise the rear end of the recording medium, so that the recording medium does not curl or the cooling efficiency does not decrease. Therefore, the air can be blown at a constant air volume without the necessity of adjusting the air volume or stopping the air blowing means, and the loss of time can be eliminated even when image formation is continuously performed on a large number of recording media.

Further, by providing a wind direction guide on both sides of the discharge tray in the discharge direction to regulate the direction of air flow,
It is possible to suppress the diffusion of the air sent out from the air blowing port, reliably form the flow of the air, reliably apply the buoyancy to the recording medium, and effectively cool the leading end of the recording medium. For this reason, it is possible to more effectively discharge and stack the suitable recording medium.

Further, by providing the air blowing port so that the air volume blown out by the air blowing means tends to decrease from substantially the center of the recording medium toward both sides, buoyancy can be effectively given to the recording medium. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram of an image forming apparatus according to a first embodiment.

FIG. 2 is a perspective view of the image forming apparatus.

FIG. 3 is an explanatory diagram of a blowing unit.

FIG. 4 is an explanatory diagram of a blowing unit.

FIG. 5 is a perspective view of the image forming apparatus.

FIG. 6 is an explanatory diagram of a discharge unit of the image forming apparatus according to the second embodiment.

FIG. 7 is an explanatory diagram of a blowing unit of an image forming apparatus according to a third embodiment.

FIG. 8 is an explanatory diagram of a discharge unit of an image forming apparatus according to a conventional example.

FIG. 9 is an explanatory diagram of a blower according to a conventional example.

[Explanation of symbols]

 P ... recording medium 1 ... image forming apparatus 2 ... feeding section 3 ... transport section 4 ... image forming section 5 ... fixing section 6 ... discharge section 7 ... manual feed tray 8 ... feeding cassette 9 ... pickup roller 10 ... separation claw 11 ... Feed roller 12… Registration roller pair 13… Transport roller 14… Transport belt 15… Photosensitive drum 16… LED 17… Development device 18… Cleaning device 19… Heater 20… Fixing roller pair 21… Discharge roller 22… Discharge tray 23… Ventilation means 24… Suction port 25… Multi-blade fan 26… Duct 27… Blast port 28… Wind direction guide 29… Maximum loading height 30… Center

Claims (5)

[Claims] A discharge roller that discharges a recording medium for recording an image, a discharge tray that is disposed below the discharge roller and stacks a recording medium, and that air is blown on a loading surface of the discharge tray on which the recording medium is stacked. An image forming apparatus, comprising: a blower that sends air; a blower port of the blower is provided between a nip of the discharge roller and a maximum stacking height of the discharge tray. 2. The image forming apparatus according to claim 1, wherein the air outlet is provided between a nip of the discharge roller and a lowermost portion of the discharge roller. 3. The image forming apparatus according to claim 1, wherein the blower blows the air at a constant air volume when discharging the recording medium after image recording. 4. The image forming apparatus according to claim 1, further comprising a wind direction guide for restricting a direction in which air flows on both sides of the discharge tray in a discharge direction. 5. The air outlet according to claim 1, wherein the air outlet is configured so that the air volume blown out by the air blowing means has a tendency to decrease from the substantially center of the recording medium toward both sides. 2. The image forming apparatus according to claim 1.