JP2002114432A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact image forming device capable of highly precisely conforming a sheet finished with image formation on a paper discharging tray even when a picture image is formed on the sheet at different processing speeds. SOLUTION: This image forming device is furnished with a paper discharging roller 14 having a plural number of processing speeds and to discharge a sheet P finished with image formation onto the paper discharging tray 71, a side wall 26 which is an interfacing surface continued to the paper discharging tray 71, a fan 72 provided inside a frame body 2 and to generate an air current 27 directed toward the side wall 26 from an upper part of the paper discharging tray 71 and a rotating control means 84 to rotate the fan 72 by a plural number of air blasting force.

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 such as a printer, and more particularly, to an image forming apparatus having a plurality of process speeds for switching process speeds at the time of switching resolutions and capable of aligning sheets on which images have been formed.

[0002]

2. Description of the Related Art Hitherto, the resolution of this type of image forming apparatus has been increased, and the resolution is 600 dpi (dot / inch).
An image forming apparatus having a high resolution mode of 200 dpi has been manufactured. For example, if the resolution is 6
When the resolution is changed from 00 dpi to 1200 dpi, the number of rotations of the polygon mirror in the scanner unit of the laser beam image forming apparatus must be doubled, and it becomes necessary to rotate the polygon mirror at high speed. Problems arise. That is, it is necessary to increase the accuracy of the polygon mirror by increasing the speed of the polygon mirror so that the bearing is not in contact with the polygon mirror, thereby increasing the cost. As a countermeasure for this problem, 1200 dpi for 600 dpi mode
In a mode, an image forming apparatus of a resolution and process speed switching type that switches the process speed to half and operates at 1200 dpi has been manufactured.
With such a process speed switching method, the number of rotations of the polygon mirror can be kept constant irrespective of the resolution, so that there is no problem in terms of technical and manufacturing costs of the scanner unit.

Further, the conventional image forming apparatus is provided with a sheet discharging device for stacking sheets on which images have been formed in an aligned state. For example, JP-A-11-2787
Japanese Patent Publication No. 39 discloses an image forming apparatus including a paper discharge device including a paper discharge tray and a fan for blowing air upward from the paper discharge tray. That is, in a normal image forming apparatus, a paper discharge tray is provided below a paper discharge port, and a slit (a groove penetrating through the tray) is provided in the paper discharge tray to facilitate taking out sheets. I have.

Accordingly, in such an image forming apparatus, 1
When the sheet is discharged, the air between the discharge port and the discharge tray is discharged downward from the slit due to the drop of the sheet. On the other hand, in the discharge of the second and subsequent sheets, since the slit is closed by the first sheet, the escape path of air is reduced. For this reason, the second and subsequent sheets slide on the slope of the paper discharge tray due to the resistance of the air where there is no escape space between the sheets, and move to a predetermined stacking position (the end of the paper discharge tray on the image forming apparatus body side). Slide down to
The second sheet is placed at the landing point without slipping down on the slope of the sheet discharge tray because it does not receive much air resistance. Therefore, in the ordinary image forming apparatus, the placement position of the first sheet is shifted with respect to other sheets, so that the matching is deteriorated.

Therefore, in the image forming apparatus disclosed in the above publication, air is blown upward from the discharge tray by a fan. Thus, air resistance can be given to the first sheet, so that the first sheet can be placed at a predetermined stacking position similarly to the second and subsequent sheets.

[0006]

However, the image forming apparatus disclosed in this publication does not specify the drop position of the sheet, and after dropping, uses the sheet's own weight to slightly reduce the frictional force. Because the top is slid, the sheet is charged, curled,
If the surface friction coefficient is high, it becomes difficult to slide,
It is difficult to guide to a predetermined loading position. In particular, since the second and subsequent sheets are not subjected to buoyancy by the fan, the influence of charging, curling, and surface friction coefficient is large, and stacking failure is likely to occur.

Further, in the case of an image forming apparatus having a plurality of process speeds, the discharge speed at which sheets are discharged to a paper discharge tray varies depending on the process speed, so that the recording paper to be discharged is stacked at a different position on the discharge tray. It was easy to cause loading failure. Furthermore, when the recording paper is discharged onto the discharge tray at a high speed, and when the height from the discharge outlet to the discharge tray is high, the sheet discharge speed is faster than the sheet drop speed. Occurs. In recent years, the number of sheets that can be stacked on the discharge tray has increased, and usually 500 sheets can be stacked. This causes a problem that the next sheet is discharged to the discharge tray while the sheet is falling onto the discharge tray, resulting in a stacking failure.

The present invention has been made in view of such a problem, and an object of the present invention is to drop an image-formed sheet having a different process speed so as to be in contact with an alignment surface to align the sheet. It is an object of the present invention to provide an image forming apparatus capable of improving the performance and preventing the next sheet from being ejected while the previous sheet falls and the sheets from being disturbed.

[0009]

In order to achieve the above object,
An image forming apparatus according to a first aspect of the present invention is an image forming apparatus having a plurality of process speeds, wherein a sheet discharging means for discharging a sheet on which an image has been formed onto a sheet discharging tray, and an alignment continuous with the sheet discharging tray. Surface, a fan for generating an airflow from the upper part of the paper discharge tray toward the alignment surface, and rotation control means for rotating the fan with a plurality of wind blasts.

According to this structure, in an image forming apparatus having a plurality of process speeds, even when the discharge speed for discharging a sheet is different for each of the plurality of process speeds, an airflow corresponding to the process speed is generated by a discharge tray. It is designed to flow toward the upper matching surface. This allows
Even if sheets with different ejection speeds are ejected to the sheet ejection tray, the sheet can be brought into contact with the alignment surface by utilizing the pressure difference caused by the airflow at the lower part of the sheet falling toward the sheet ejection tray. . Accordingly, since the end portions of the sheets having different discharge speeds can be aligned by the alignment surface, even if the sheets having different process speeds are continuously discharged, a highly accurate aligned sheet bundle can be formed.

According to a second aspect of the present invention, there is provided an image forming apparatus comprising:
The fan is provided inside a frame of the image forming apparatus. According to this configuration, since the fan is provided inside the frame of the image forming apparatus, the structure can be made compact.

According to a third aspect of the present invention, in the image forming apparatus according to the first or second aspect, when the process speed is high, the rotation control means increases the number of rotations of the fan. When the process speed is low, control is performed so as to reduce the rotation speed of the fan.

According to this configuration, when the discharge direction of the discharge means is different from the direction of the air flow, and when the process speed is high, the sheet is discharged by the discharge means in a vigorous manner by jumping out to the far side. Therefore, by setting the rotation speed of the fan to be high, the sheet can be pulled back and brought into contact with the alignment surface by using a relatively large pressure difference at the lower portion of the sheet falling toward the sheet discharge tray. Become.
Also, when the process speed is high, the sheets are continuously discharged to the paper output tray at a high speed. Paper can be discharged.

[0014] The rotation control means controls the rotation speed of the fan to be reduced when the process speed is low. According to this configuration, when the process speed is low, the sheet is discharged to the vicinity of the side wall of the image forming apparatus by the discharging unit. In this case, if the number of rotations of the fan is higher than necessary, the rear end portion of the sheet from the center is sucked to the side wall, and a stacking failure of the discharged sheet occurs. Therefore, if the process speed is slow, set the number of rotations of the fan to a low value, and use the relatively small pressure difference at the bottom of the sheet that is falling toward the output tray to pull the sheet back to the alignment surface. It is possible to make contact.

According to a fourth aspect of the present invention, there is provided an image forming apparatus comprising:
4. The image forming apparatus according to claim 1, wherein the alignment surface is provided on a side wall of the frame, and a ventilation hole is provided on the side wall, and the fan is provided on the discharge tray. 5. It is characterized in that it is set so that the upper air is sent into the inside of the frame through the ventilation hole. According to this configuration, since the alignment surface is provided on the side wall of the image forming apparatus, the structure can be simplified, and the inside of the frame can be ventilated and cooled.

According to a fifth aspect of the present invention, there is provided an image forming apparatus comprising:
5. The image forming apparatus according to claim 4, wherein the fan is set so as to blow air on the discharge tray to the fixing unit in the frame through the ventilation hole. According to this configuration, it is possible to prevent an excessive rise in the temperature of the fixing unit by using the airflow used for the sheet alignment. Thus, since it is not necessary to separately provide a cooling device for the fixing unit, the configuration of the image forming apparatus can be simplified, and the manufacturing cost can be reduced.

According to a sixth aspect of the present invention, there is provided an image forming apparatus comprising:
2. The image forming apparatus according to claim 1, wherein the rotation control unit changes the rotation speed of the fan according to a set temperature of a heating member of the fixing unit set for each of the plurality of process speeds. 3. I have. According to this configuration, energization from the commercial power supply to the heating member is performed in accordance with the set temperature of the fixing unit set for each of the plurality of process speeds.
By turning on / off and changing the number of rotations of the fan, it is possible to set the number of rotations of the fan according to the temperature in the frame of the image forming apparatus.

According to a seventh aspect of the present invention, there is provided an image forming apparatus comprising:
7. The image forming apparatus according to claim 6, wherein the rotation control unit controls to increase the number of rotations of the fan when the set temperature of the heating member is high, and when the set temperature of the heating member is low. Is characterized in that the number of rotations of the fan is controlled to be reduced. According to this configuration,
When the heating temperature of the fixing unit is high, the temperature in the frame of the image forming apparatus rises sharply.
In addition, by increasing the number of rotations of the fan, it is possible to prevent the temperature in the frame from rapidly increasing. Further, when the heating temperature of the fixing unit is low, the rise in the temperature in the frame of the image forming apparatus is low, so that the occurrence of defective fixing due to excessive cooling of the fixing unit can be prevented by reducing the rotation speed of the fan.

An image forming apparatus according to an eighth aspect of the present invention comprises:
The image forming apparatus according to any one of claims 5 to 7, further comprising a blower guide extending from the fan toward the fixing unit. According to this configuration, the air blown by the fan can be efficiently applied to the fixing unit, and the cooling effect on the fixing unit can be enhanced.

According to a ninth aspect of the present invention, there is provided an image forming apparatus comprising:
9. The image forming apparatus according to claim 5, wherein the fan is provided below the fixing unit in the frame. According to this configuration, the airflow generated by the fan can be smoothly flown toward the fixing unit without opposing the rising airflow due to the heat generated by the fixing unit, and the cooling efficiency can be increased.

An image forming apparatus according to a tenth aspect of the present invention is the image forming apparatus according to any one of the first to ninth aspects, wherein the image forming apparatus is provided on an upper portion of the paper discharge tray and discharges a sheet being discharged. It is characterized by having an auxiliary fan that generates an airflow that presses in the tray direction. According to this configuration, the sheet that is falling to the sheet discharge tray can be more reliably inclined by the wind pressure of the auxiliary fan so that the alignment surface side is lowered. Because of the resistance, the sheet falls so as to more reliably contact the alignment surface, so that the sheet alignment can be further improved.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of an image forming apparatus according to the present invention will be described below in detail with reference to the drawings. FIG.
FIG. 2 is an external view of the image forming apparatus according to the present embodiment.
FIG. 2 is a cross-sectional view illustrating a main configuration of the image forming apparatus. Figure 1,
As shown in FIG. 2, the image forming apparatus 1 includes a scanner unit A, an image forming unit B indicated by a broken line, a sheet conveying unit C, and an operation panel D. The scanner unit A irradiates a document with light and generates image data corresponding to the image of the document from the reflected light. The image forming unit B forms a toner image (developer image) based on the image data generated by the scanner unit A, and forms the toner image on a predetermined recording sheet (sheet).

The sheet transport section C supplies sheets to the image forming section B and discharges the sheets on which images have been formed. The operation panel D (see FIG. 1) is an interface for transmitting a user's instruction to the image forming apparatus 1 and displaying an operation state of the image forming apparatus 1 to the user. Is provided on the front side of the frame 2.

Next, each part of the image forming apparatus 1 will be described in detail. First, the scanner unit A will be described. As shown in FIG. 2, the scanner unit A has a document table 3 made of transparent glass or the like on the upper surface of the frame 2. A cover 4 for holding a document is supported above the document table 3 so as to be openable and closable, and a scanner optical system 10 is arranged below the document table 3. The scanner optical system 10 includes an exposure lamp 11, reflecting mirrors 12a and 12b,
Reflective optical system 12 composed of 12c, imaging lens 1
3. A photoelectric conversion element (hereinafter, referred to as a CCD) 14 is provided. The exposure lamp 11 is a light source for scanning the original with light by reciprocating below the original table 3.

The reflecting mirrors 12a, 12b and 12c reflect the reflected light from the original, for example, as shown by a dashed line in FIG.
It leads to the imaging lens 13 and the CCD 14. CC
D14 receives the reflected light imaged by the imaging lens 13, and generates an image signal of an electric signal according to the amount of received light. This image signal is converted into digital data by an A / D converter (not shown), and then subjected to predetermined processing in an image processing unit (not shown), and is output as image data.

Next, the image forming section B and the sheet transport section C will be described in detail. As shown in FIG. 2, the image forming section B includes a photoreceptor roller 28, a charging section 29, a developing section 30, a transfer charger 31, a cleaning device 32, and a laser scanning unit (hereinafter, referred to as LSU) 51. The photoconductor roller 28 is a drum-shaped photoconductor roller, and is configured to be driven to rotate in the direction of arrow E. The charging unit 29 uniformly charges the surface of the photoconductor roller 28 to a predetermined potential. The LSU 51 exposes the charged surface of the photoreceptor roller 28 with laser light (image light modulated based on image data) to convert an electrostatic latent image corresponding to the image data into an electrostatic latent image by a photoconductive action. It is formed by forming.

The developing section 30 forms a toner image on the photosensitive roller 28 by developing the electrostatic latent image formed by the LSU 51 with the developing roller 30a. The transfer charger 31 is connected to the photosensitive roller 28.
The upper toner image is transferred to a sheet. The cleaning device 32 removes the toner remaining on the surface of the photoconductor roller 28 after the toner image is transferred onto the sheet.

Further, as shown in FIG.
Are fixed paper cassette 15, pickup roller 16,
Registration roller 17, conveyance path 18, fixing roller 23, paper discharge port 24, paper discharge roller 25, pre-registration detection switch 6
1, fixing paper detection switch 62, discharge detection switch 63,
A paper ejection tray 71 and a fan 72 are provided. The fixed paper feed cassette 15 is for storing sheets P for image formation. The pickup roller 16 outputs the sheets P one by one from the fixed sheet feeding cassette 15 and feeds the sheets P one by one.
8 is a half-moon-shaped feeding roller.

Further, the fixed sheet cassette 15 is provided with a sheet separation unit (not shown) for assisting the discharge of the sheet P. The sheet separating section can be composed of a roller and a friction sheet member or a reverse roller. The pre-registration detection switch 61 detects that the sheet P being conveyed on the conveyance path 18 has passed a predetermined position, and outputs a predetermined detection signal.

The registration roller 17 temporarily holds the sheet P being transported on the transport path 18. In addition, it has a function to convey the sheet P to the transfer charger 31 with good timing in accordance with the rotation of the photoconductor roller 28 so that the toner image on the photoconductor roller 28 can be satisfactorily transferred to the sheet P. That is, the registration roller 17
The sheet P is conveyed based on the detection signal output from the pre-registration detection switch 61 so that the leading end of the toner image on the photosensitive roller 28 is pressed against the leading end of the image forming area of the sheet P. I have.

The fixing roller 23 constitutes a fixing means together with the pressure roller 23a, and has a built-in heating member 82 such as a heater, which will be described later, and transfers the toner image on the sheet P after image formation onto the sheet P. The fixing is performed by heat, and the toner image is fused and fixed by heating and pressing. The fixing paper detection switch 62 detects that the sheet P has passed through the fixing roller 23. The discharge roller 25 is provided near the discharge port 24 and is a roller for discharging the sheet P discharged from the fixing roller 23 to the discharge tray 71. The discharge detection switch 63 is
This is to detect the discharge of the sheet P from the discharge roller 25. The fan 72 aligns the sheet P discharged onto the sheet discharge tray 71 and cools the fixing roller 23.

Here, the configuration around the fan 72 will be described with reference to FIG. FIG. 3 is an explanatory diagram showing a configuration around the fan 72. As shown in this figure,
The paper discharge tray 71 is provided below the paper discharge port 24 so as to be inclined in a direction to descend toward the main body. Further, a ventilation hole 26a formed of a mesh-like ventilation slit is provided on the side wall 26 which is an alignment surface of the image forming apparatus 1 which is continuous with the paper discharge tray 71. And this vent 2
A fan 72 is disposed on the back side (inside) of 6a and below (obliquely below) the fixing roller 23.

The fan 72 is a propeller having four blades.
The rotation is set so as to generate an airflow (flow of air) 27 from the discharge tray 71 of the image forming apparatus toward the inside of the apparatus by rotating toward the ventilation port 26a. Airflow 27
Is the discharge direction X of the sheet P discharged from the discharge roller 25
And acts in a direction to pull back the sheet P, flows around the fixing roller 23, and flows around the fixing roller 23.
Is discharged to the outside through the slit 74. In addition, fan 7
2 is near the airflow 27 generated by the fan 72.
Guide 73 for directing the toner toward fixing roller 23.
Is provided. The blowing guide 73 extends horizontally from the fan 72 toward the fixing roller 23.

Next, with reference to FIG. 4, the image forming apparatus according to the present embodiment will be further described. FIG. 4 is a block diagram illustrating a main configuration of the image forming apparatus. This image forming apparatus 1
Is a CPU 8 that transmits and receives signals from the external host device 80.
1, a heating member 82 of the fixing roller 23, a heating member control unit 83, a fan 72, a rotation control unit 84 for controlling the fan at a plurality of rotation speeds, and a sheet conveyance unit C and a sheet conveyance unit for the sheet P in a plurality of stages. Conveyor control means 8 for controlling the number of rotations
5 is provided.

The CPU 81 outputs a signal for switching the number of revolutions of the fan 72 according to the process speed,
An N / OFF signal and a control signal of the paper transport unit C are output to the rotation control unit 84, the heating member control unit 83, and the transport unit control unit 85, and the rotation control unit 84 changes the rotation speed of the fan 72 according to the PULSE signal. And heating member control means 8
3 controls the heating value by turning on / off the heating member 82;
The conveying speed of the sheet P is changed by the conveying unit control means 85.

In the image forming apparatus 1, the resolution can be switched between 1200 dpi and 600 dpi, for example, and the resolution can be switched by switching the process speed. In this example, the process speed is 60 mm / sec at a resolution of 1200 dpi.
Is set at 120 dpi, which is twice that at a resolution of 600 dpi.
mm / sec.

Here, control of the temperature of the fixing roller 23 to the heating member control means 83 and control of the rotation speed of the fan 72 will be described. In the conventional heat roller fixing control method, when the process speed is high, the paper and the pressure roller pass through the fixing nip at a high speed and are not easily heated, so that it is necessary to increase the fixing temperature. However, if the process speed is continuously reduced as it is, the temperature becomes higher than the appropriate temperature, and hot offset occurs. The hot offset means that the toner fuses to the roller due to overheating of the toner due to high temperature. In order to avoid this, it is necessary to take a long space between the sheets and consume heat by performing idle rotation of the fixing device with the heater turned off.

Conversely, when the process speed is low, the paper and the pressure roller pass through the fixing nip at a low speed and are difficult to cool. Therefore, it is necessary to lower the fixing temperature. Lower, causing a cold offset. Cold offset refers to a state in which the amount of heat is insufficient and toner is not fixed on a sheet. To avoid this, the heater O
In the state of N, it was necessary to wait for the temperature of the fixing device to rise. Therefore, it is necessary to speed up the transition to the next process by performing heater control and fan control of the heating member according to the process speed. As described above, there is a technique disclosed in Japanese Patent Application Laid-Open No. 6-332330 as a technique having a fan control means for switching the fan speed when the process speed is switched.

The operation of the image forming apparatus 1 according to this embodiment having the above-described configuration will be described below. When the process speed is high, the temperature inside the image forming apparatus 1 is high because the temperature of the heating member 82 of the fixing roller 23 and the temperature of the pressure roller 23a are high. Improve ability. On the other hand, when the process speed is low, since the temperature in the image forming apparatus 1 is low, the fan 72 is controlled to rotate at a low rotation speed to reduce the cooling capacity.

First, a resolution of 600 dpi to a resolution of 12
FIG. 5 shows a case where the resolution is switched to 00 dpi.
Will be described below. When printing at a resolution of 600 dpi (process speed of 120 mm / sec), control is performed with a fixing temperature of 200 ° C. and a fan rotation speed (75%; high-speed rotation). After that, the resolution from 600 dpi to 12
When the sheet passes through the fixing roller 23 and the pressure roller 23a in order to switch to 00 dpi, the process speed is switched from 120 mm / sec to 60 mm / sec, and the temperature set value is also set to 1 for 60 mm / sec.
Switch to 90 ° C.

The current temperature value is compared with the next temperature set value. If the temperature is high, the heating member control means 83 is turned off.
By lowering the temperature of the heating member 82 by doing
The fan 72 is rotated by the rotation control means 84 at a high rotation speed (100
%) To quickly shift to the temperature set value, thereby reducing the preparation operation time. After the second print, the fan 72 is rotated at a high rotation speed (100%) to lower the temperature. When the process speed is high, the fan 72 can be rotated at high speed to prevent the temperature inside the apparatus frame 2 from excessively rising. Next, the case where the resolution is switched from 1200 dpi to 600 dpi will be described with reference to FIG. explain. Resolution 1200 dpi (process speed 60
mm / sec), control is performed with a fixing temperature of 190 ° C. and a fan rotation speed (50%; low-speed rotation). Thereafter, when switching from the resolution of 1200 dpi to the resolution of 600 dpi, when the sheet passes through the fixing roller 23 and the pressure roller 23a, the process speed is reduced to 60 mm / sec.
c to 120 mm / sec, and at the same time, the temperature set value is also switched to 200 ° C. for 120 mm / sec.

The current temperature value is compared with the next temperature set value. If the temperature is high, the temperature of the heating member 82 is raised by turning on the heating member control means 83, and the fan 72 is stopped to stop the rotation speed. (0%) to quickly shift to the temperature set value, thereby reducing the preparation operation time. After the second print, the fan 72 is rotated at a high rotation speed (100%) to lower the temperature.

Here, the alignment of the sheet P by the fan 72 will be described. FIGS. 7A to 7C are explanatory diagrams illustrating a discharge state of a sheet P in a conventional image forming apparatus. As shown in these figures, in the conventional apparatus, when the process speed is 60 mm / sec (1200 dpi), the apparatus is mounted on the main body side (right side). Further, when the process speed is 120 mm / sec (600 dpi), the sheet P is discharged in a form protruding farther (leftward),
While the sheet P discharged in the X direction from the paper discharge port 24 falls on the paper discharge tray 71, it moves to a position (left side) away from the main body due to inertia of discharge and is placed at that position.
For this reason, when the sheets P are successively discharged with the resolution changed, the placement position is shifted for each sheet P, and the consistency as a sheet bundle cannot be achieved.

FIGS. 8A to 8C are explanatory views showing the discharge state of the sheet P in the image forming apparatus when there is only one kind of wind force. In the image forming apparatus shown in these figures, the discharge speed of the discharged paper differs depending on the process speed.
However, even if it is sucked to the main body side (right side) by the airflow 27 generated by the fan 72 while it falls on the paper discharge tray 71, it cannot be placed at a position where it comes into contact with the side wall 26 of the main body.

That is, the process speed is 60 mm /
sec (1200 dpi), sheet P is fan 7
2 and is brought into contact with the side wall 26 to be aligned, but the process speed is 120 mm / sec (6 mm).
In the case of 00 dpi), since the sheet P has a large inertia, the sheet P does not come into contact with the side wall 26 even when pulled back by the airflow 27, and is placed on the sheet discharge tray 71 at a position shifted leftward. For this reason, the sheet bundle does not match.

On the other hand, FIGS. 9A to 9C show the sheet P in the image forming apparatus 1 in the case where there are a plurality of types of blowing air.
It is an explanatory view showing a discharge state. As shown in these drawings, in the image forming apparatus 1, even when the sheet P is discharged at a plurality of discharge speeds, the sheet P is discharged in the X direction even when the sheet P is discharged at a plurality of discharge speeds. While the dropped sheet P falls on the sheet discharge tray 71, the sheet P is sucked toward the main body by the airflow 27 generated by the fan 72 and is placed at a position where it comes into contact with the side wall 26 of the main body.

When the process speed is high, the fan 72
Is rotated at a high speed, and the wind force is increased to strongly pull the sheet P back and abut the side wall 26. When the process speed is low, the fan 72 is rotated at a low speed to reduce the amount of wind to be sent, and is brought into contact with the side wall 26. For this reason, even if the sheets P are continuously discharged with the process speed changed, the placement positions of all the sheets P can be aligned by the side walls 26, so that the alignment as a sheet bundle can be achieved with high accuracy. Become.

Even if the sheet P is continuously discharged to the discharge tray at a high speed, the airflow 27 generated by the fan 72 causes
Since the falling speed of the sheet P is increased, there is no problem that the next sheet P is discharged to the discharge tray while the sheet P is dropped onto the discharge tray 71. As described above, the image forming apparatus 1 includes the fan 72 that generates the airflow 27 from the discharge tray 71 toward the side wall 26, and changes the rotation speed of the fan. Thus, the sheet P falling toward the sheet discharge tray 71 can be reliably brought into contact with the side wall 26. Accordingly, since the end portions of the sheets P are aligned by the side wall 26, even if a plurality of sheets P are continuously discharged at different resolutions, a sheet bundle aligned with high accuracy can be formed.

In the image forming apparatus 1, the sheet P is aligned by the side wall 26. Further, a ventilation port 26 a is provided on the side wall 26, and the fan 72 provided inside the image forming apparatus 1
The air on the paper discharge tray 71 is set to be sent into the frame 2 of the image forming apparatus 1 through 6a.
Thereby, since the side wall 26 is used as an alignment surface,
There is no need to separately provide an alignment surface, so that the cost for alignment can be reduced and the structure can be simplified. In addition, since the fan 72 is provided inside the frame 2, the structure can be made compact.

Further, in the present image forming apparatus 1, the fan 7
2 is blown to the fixing roller 23 through the ventilation opening 26a and the air guide 73. Thus, the fixing roller 23 can be cooled using the airflow used for the alignment of the sheet P. Therefore, since it is not necessary to separately provide a cooling device for the fixing roller 23, the configuration of the image forming apparatus 1 can be simplified, and the manufacturing cost can be reduced. Further, in the image forming apparatus 1, the fan 72 is provided below the fixing roller 23. This allows the airflow 27 generated by the fan 72 to flow smoothly toward the fixing roller without opposing the rising airflow due to the heat generated by the fixing roller.

In the present embodiment, the sheet P is brought into contact with the side wall 26 to achieve the alignment.
Further, a ventilation port 26a is provided below the paper discharge port 24, and on the back side (inside), the fan 72 is connected to the ventilation port 26a.
, The airflow 27 is generated such that the sheet P comes into contact with the side wall 26. Since the fan 72 is located below the fixing roller 23, the airflow 27 can cool the temperature inside the frame 2 without directly and rapidly cooling the fixing roller 23.

As shown in FIGS. 10 and 11 (a) to 11 (c), an auxiliary fan 75 for assisting the cooling of the fixing roller 23 may be provided above the discharge tray 71. Good. The auxiliary fan 75 is connected to the fixing roller 2.
3, and generates an airflow 76 that flows the air in the frame 2 toward the discharge tray 71. The air volume of the auxiliary fan 75 is set to a smaller value than that of the fan 72. That is, this auxiliary fan 7
5 is configured to generate a weak airflow 77 in such a direction that the sheet P to be discharged is pressed against the discharge tray 71. The rotation speed of the auxiliary fan 75 is desirably rotated at an output of 25% to 50% in the rotation control method of the fan described with reference to FIG.

With this configuration, the sheet P being dropped onto the sheet discharge tray 71 can be more reliably inclined by the wind pressure of the auxiliary fan 75 such that the side wall 26 as the alignment surface is lowered. In operation, since the sheet P falls down so as to more reliably contact the side wall 26 due to the air resistance at the lower portion of the sheet P, the consistency of the sheet P can be further improved.

In the above embodiment, the sheet P
Although the case where the discharge direction of the sheet P and the direction of the airflow 27 are different and the sheet P is pulled back has been described, the sheet may be accelerated when the discharge direction of the sheet P and the direction of the airflow 27 are the same. That is, when the process speed is high, the acceleration due to the airflow is small, so that the rotation of the fan can be slowed. When the process speed is low, the acceleration due to the airflow is more necessary, so that the rotation of the fan needs to be accelerated.

[0055]

As can be understood from the above description, in the image forming apparatus of the present invention, even if sheets having different process speeds are successively discharged in the image forming apparatus having a plurality of process speeds, Sheets can be aligned on the tray with high precision. Further, the size of the image forming apparatus can be reduced. Further, it is possible to prevent the temperature inside the frame of the image forming apparatus from excessively rising.

[Brief description of the drawings]

FIG. 1 is an external view of an embodiment of an image forming apparatus according to the present invention.

FIG. 2 is a cross-sectional view illustrating a main configuration of the image forming apparatus of FIG. 1;

FIG. 3 is an enlarged view of a main part of a discharge tray portion of FIG. 1;

FIG. 4 is a block diagram illustrating a main configuration of the image forming apparatus of FIG. 1;

FIG. 5A is a diagram illustrating the air flow of a fan when the resolution is increased, and FIG. 5B is a diagram illustrating the temperature of the fixing roller at that time.

FIG. 6A is a diagram illustrating the air flow of a fan when the resolution is reduced, and FIG. 6B is a diagram illustrating the temperature of the fixing roller at that time.

7A and 7B show a conventional operation state without a fan, wherein FIG. 7A is a sheet discharge state diagram, FIG.
(C) is a view showing a mounted state of a sheet.

8A and 8B show an operation state of a conventional fan having a single air flow, where FIG. 8A is a sheet discharge state diagram, FIG. 8B is a fan air blow state diagram, and FIG. 8C is a sheet placement state diagram. .

9A and 9B show an operation state of the present invention, in which FIG. 9A is a state diagram of sheet discharge, FIG. 9B is a state diagram of air blowing of a fan, and FIG.

FIG. 10 is a main part configuration diagram showing another embodiment of the present invention.

11A and 11B show the operation state of FIG. 10, in which FIG. 11A is a sheet discharge state diagram, FIG. 11B is a fan blowing state diagram, and FIG. 11C is a sheet placement state diagram.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Image forming apparatus 2 Frame 23 Fixing roller (fixing means) 24 Discharge port 25 Discharge roller (discharge means) 26 Side wall (alignment surface) 26a Ventilation port 27 Air flow 71 Discharge tray 72 Fan 73 Ventilation guide 75 Auxiliary fan 77 Air flow 82 Heating member 83 Heating member control means 84 Rotation control means 85 Conveyance unit control means B Image forming unit C Paper conveyance unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI theme coat ゛ (reference) G03G 15/20 109 G03G 15/20 109 F term (reference) 2H033 AA14 BA10 BA29 CA04 CA07 CA22 CA53 2H072 AB07 BA03 BA13 CA01 CA02 CB09 3F049 AA02 DA12 FA05 FA08 FC09 FC17 LA07 LB03 3F054 AA01 AC05 BA04 BB16 BH02

Claims (10)

[Claims] 1. An image forming apparatus having a plurality of process speeds, a paper discharge means for discharging an image-formed sheet onto a paper discharge tray, an alignment surface continuous with the paper discharge tray, and An image forming apparatus comprising: a fan configured to generate an air current flowing from an upper portion toward the alignment surface; and a rotation control unit configured to rotate the fan by a plurality of wind blasts. 2. The image forming apparatus according to claim 1, wherein the fan is provided inside a frame of the image forming apparatus. 3. The control device according to claim 2, wherein said rotation control means increases the rotation speed of said fan when the process speed is high, and decreases the rotation speed of said fan when the process speed is low. Item 3. The image forming apparatus according to Item 1 or 2. 4. The alignment surface is provided on a side wall of the frame, and a ventilation hole is provided on the side wall.
4. The image forming apparatus according to claim 1, wherein the fan is configured to send air on the discharge tray to the inside of the frame through the ventilation port. 5. 5. The image forming apparatus according to claim 4, wherein the fan is configured to blow air on the discharge tray to the fixing unit in the frame through the ventilation port. . 6. The apparatus according to claim 1, wherein the rotation control unit changes the number of rotations of the fan according to a set temperature of a heating member of the fixing unit set for each of the plurality of process speeds. The image forming apparatus as described in the above. 7. The rotation control means controls to increase the rotation speed of the fan when the set temperature of the heating member is high, and to control the rotation speed of the fan when the set temperature of the heating member is low. The image forming apparatus according to claim 6, wherein the image forming apparatus is controlled so as to reduce the image quality. 8. The image forming apparatus according to claim 5, further comprising a blower guide extending from the fan toward the fixing unit. 9. The image forming apparatus according to claim 5, wherein the fan is provided below the fixing unit in the frame. 10. An apparatus according to claim 1, further comprising an auxiliary fan provided at an upper portion of said sheet discharge tray to generate an airflow for pressing a sheet being discharged toward said sheet discharge tray. An image forming apparatus according to any one of the above.