JP2000235339A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming device making the temp. rise inside restrained to a very low level, even in the case of setting the developing unit close to the fixing device from the view point of layout for the device. SOLUTION: In an image forming device of electrophotographic system provided with the developing unit forming the toner image, the fixing device making the toner image on transfer paper fixed, and a fan feeding an air flow 17 for cooling the developing unit, the image forming device has an air cooling duct 16 provided with a separation blade 20 for letting the air flow 17 from the fan to flow and separating the inside into 2 layers of the developing unit and the fixing device. Moreover, the separation blade 20 in the duct for cooling the air makes the air flow of the fan separated so as to flow to 2 layers of the developing unit side and the fixing device side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in an electrophotographic image forming apparatus such as a printer, a facsimile machine, a copying machine, or a multifunction machine thereof. The present invention relates to an image forming apparatus capable of preventing conduction to the image forming apparatus.

[0002]

2. Description of the Related Art A heat fixing device used in an electrophotographic image forming apparatus is heated to a high temperature of 120 ° C. or more to fix a toner image formed on a transfer sheet. On the other hand, it is preferable that the developing unit that holds the toner and the like used for the development be kept at a normal temperature as much as possible to avoid deterioration of the toner. It is known that the life of a toner is extremely shortened at a high temperature, and the performance is deteriorated because the characteristic value of charge amount (Q) / mass (M) becomes small. Therefore, the developing unit is generally cooled by an electric fan. For example, in a "cooling device in an image forming apparatus" described in Japanese Patent Application Laid-Open No. 9-222841, a cooling fan is disposed at an angle from a cooling fan by using a casing of a printer body and arranging the cooling fan at an angle. Has improved cooling performance. Further, in the “electrophotographic recording device” described in Japanese Patent Application Laid-Open No. 9-222841, the power supply unit is hardly subjected to heat from an adjacent fixing device.
After the power supply is cooled vertically downward from above, the cooled air is used to prevent heat from being transmitted from the fixing device. That is, an invention is known in which the shape of the casing is set or a duct is provided so as to guide the airflow of the fan in a specific direction, thereby increasing the cooling efficiency of cooling the developing unit by the airflow of the fan.

[0003]

However, in the case where the developing unit is disposed close to the fixing device due to recent demands for downsizing of the image forming apparatus or the like, as described above, the airflow of the fan is merely determined by the casing shape or the duct. It is no longer sufficient to guide the person in a specific direction. For example, when the temperature of a toner (developer) in a color developing device is higher than 38 degrees Celsius, the Q / M characteristic value is extremely changed (deteriorated).
However, this causes toner scattering or toner life deterioration. Therefore, in a color developing device, if the guaranteed temperature of the machine is 32 degrees Celsius, it is necessary to suppress the internal temperature rise to 6 degrees Celsius or less. However, when the developing unit and the fixing device are close to each other due to the layout, it is very difficult to suppress the internal temperature rise to a low value of 6 degrees Celsius or less by only the conventional method. In the present invention,
It is an object of the present invention to provide an image forming apparatus that can suppress an internal temperature rise to a very low level even when a developing unit is close to a fixing device in the layout of the image forming apparatus.

[0004]

According to an aspect of the present invention, there is provided an image forming apparatus, comprising: a developing unit for forming a toner image; and a fixing device for fixing the toner image on a transfer sheet. And a fan for sending an air flow for cooling the developing unit, wherein the developing unit includes an air cooling duct having a partition plate through which the air flow from the fan is passed and the inside of which is divided into two layers. And the fixing device. According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the partition plate in the air cooling duct divides the airflow of the fan into two layers of the developing unit side and the fixing unit side. It is characterized by the following. According to a third aspect of the present invention, in the image forming apparatus according to the second aspect, the number of the fans is one.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described based on illustrated embodiments. FIG. 1 is a schematic configuration diagram showing a part of an internal mechanism of a full-color laser beam printer (LBP) which is an embodiment of the image forming apparatus of the present invention.
As shown in FIG. 1, a full-color laser beam printer (hereinafter, referred to as a printer) of the present embodiment includes a photosensitive drum 1 as an image carrier for forming an image on a surface thereof, and a photosensitive drum 1 for charging the photosensitive drum 1. A charging unit 2, a writing unit 3 for generating a writing laser beam, and each color (black (Bk), yellow (Y), cyan (C), magenta (M) for developing an electrostatic latent image to form a toner image. )) And the developing unit 4
developing unit supporting portion 5 rotatably supporting a to 4d
And an intermediate transfer belt 6 for once forming an image in which images of the respective colors overlap, a pre-cleaning charger 7 for removing charges before cleaning, and a photoconductor cleaning unit 8 for cleaning remaining toner on the photoconductor drum 1.
, A charge eliminator 9 for removing charges charged on the photosensitive drum 1, a secondary transfer belt 10 for conveying a transfer paper 18 onto which a toner image has been transferred, and a cleaning for cleaning residual toner on the intermediate transfer belt 6. A unit 11, a separation charger 12 for generating an electric charge for separating the transfer paper 18 from the secondary transfer belt 10, a conveying unit 13 for conveying the transfer paper 18 to a fixing device 14 described below, and a toner image on the transfer paper 18. Fixing unit 14 for fixing, and developing units 4a to 4
A fan 15 for generating an air flow 17 for cooling the air flow d and the like, and a duct 16 for guiding the air flow 17 are provided. The developing units 4a to 4d correspond to black (Bk), yellow (Y), cyan (C), and magenta (M), respectively. The duct 16 extends along the slight space between the developing units 4a to 4d and the fixing device 14 to form the developing unit 4a.
4d are arranged so as to be shielded from the fixing device 14.

The transfer paper 18 fed from a paper feed cassette or the like inside the image forming apparatus is conveyed to a registration roller (not shown) provided near the transfer position of the intermediate transfer belt 6. The photosensitive drum 1 driven to rotate in the direction of the arrow is
The surface is uniformly charged by the charging charger 2, and is scanned by a laser beam modulated according to image data from the writing unit 20 to form an electrostatic latent image on the surface.
The electrostatic latent image formed on the photosensitive drum 1 becomes a toner image to which toner is attached by one of the developing units 4a to 4d and is visualized. The toner image on the photosensitive drum 1 is transferred onto the intermediate transfer belt 6. From the formation of the electrostatic latent image on the photosensitive drum 1 to the transfer of the toner image to the intermediate transfer belt 6, each color (black (B
k), yellow (Y), cyan (C), magenta (M)). On the intermediate transfer belt 6, black (Bk) → yellow (Y) → cyan (C)
→ The toner images are superimposed and transferred in the order of magenta (M).
When the four color toner images are superimposed on the intermediate transfer belt 6, the secondary transfer belt 10 contacts the intermediate transfer belt 6. The transfer paper 18 is conveyed on the secondary transfer belt 10 and is discharged by the separation charger 12 to be separated from the secondary transfer belt 10. The transfer paper 18 from which the charge has been removed is subsequently conveyed to the fixing device 14 by the conveying means 13. The four color toner images on the transfer paper 18 are fixed by the fixing device 14. After the toner image has been transferred onto the intermediate transfer belt 6, the photosensitive drum 1
After a reverse charge is once applied by the pre-cleaning charger 7, the photosensitive member is cleaned by the photoreceptor cleaning unit 8, and the charge is removed by the charge remover 9 to form the next electrostatic latent image. On the other hand, the intermediate transfer belt 6 after the transfer of the four color toner images to the secondary transfer belt 10 is cleaned by the belt cleaning unit 11. Duct 1
6 is provided between the developing units 4 a to 4 d and the fixing device 14 so as to cover both of them, and an airflow (outside air outside the apparatus) 17 generated from the fan 15 is provided in an opening provided in an upper portion of the duct 16. The duct 19 flows into the duct 16, flows inside the duct 16, and is discharged from another opening 19 b provided at the rear end or lower end of the duct 16.

FIG. 2 is a view showing a detailed structure of the duct 16 of FIG. 1, and FIG. 3 is a sectional view taken along line AA 'of FIG.
As shown in FIGS. 2 and 3, inside the duct 16, an upper airflow 17 a and lower airflows 17 b and 17
The partition plate 20 is provided so as to partition the partition wall c from the partition wall c. An opening 23 (19b) that is opened in a slit shape is provided at a position on the side plate 16d side of the upper lid 16a of the duct 16. An opening 22 is provided on the side of the side plate 16 c of the duct 16.
Is provided, and the lower airflow 17 discharged from the opening 22 is provided.
A discharge duct 21 for guiding b and 17c from the duct 16 to a predetermined discharge position is connected. Also, the side plate 1
A partition plate 24 is provided inside 6d at a position closer to the side plate 16d than the opening 23 and parallel to the side plate 16d. The airflows 17a to 17c generated from the fan 15 flow from the opening 19 of the duct 16 and are separated by the partition plate 20.
Air flow 1 flowing above partition plate 20 in duct 16
7a and an airflow 17b, 17c flowing below.
The upper airflow 17 a flows between the upper lid 16 a of the duct 16 and the partition plate 20 to the partition plate 24 and is discharged from the opening 23. One lower airflow 17 b flows between the lower lid 16 b of the duct 16 and the partition plate 20 to the partition plate 24, then flows along the partition plate 24, and from the opening 22 through the discharge duct 21. Is discharged. The other lower airflow 17c
Flows to the partition plate 24 between the lower lid portion 16b of the duct 16 and the partition plate 20, and is discharged from the opening 22 through the discharge duct 21.

In FIG. 2, only the airflow 17a flowing in the upper central portion of the duct 16 is shown, but the airflow 17a flowing on the upper side flows entirely between the upper lid 16a of the duct 16 and the partition plate 20. . FIG. 2 shows only the airflows 17b and 17c flowing through both ends of the duct 16,
The air flows 17b and 17c flowing on the lower side flow through the entire space between the lower lid 16b of the duct 16 and the partition plate 20. The air flows 17b and 17c flowing on the lower side absorb the heat radiated from the fixing device 14 toward the lower lid 16b of the duct 16 or the heat conducted through the air, and are discharged from the opening 22 through the discharge duct 21. Is done. Therefore, heat radiated or conducted from the fixing device 14 toward the lower lid 16 b of the duct 16 is not directly absorbed by the airflow 17 a flowing on the upper side shielded by the partition plate 20. Therefore, in the present invention, the upper airflow 17a generated from the fan 15 is:
The developing units 4a to 4d are cooled with almost no temperature rise due to the heat from the fixing unit 14, so that even when the developing unit comes close to the fixing device from the layout, the internal temperature rise is suppressed to a very low level. Can be
Deterioration of the toner in the color developing device can be avoided. Further, in the present invention, the airflow generated from one fan 15 and flowing into the duct is divided by the partition plate 20 to form two paths of an airflow 17a flowing on the upper side in the duct 16 and airflows 17b and 17c flowing on the lower side. Since the airflow is a flowing airflow and two paths of airflow are obtained without adding a fan, the configuration can be simplified and the cost can be reduced.

[0009]

As described above, according to the first and second aspects of the present invention, even when the developing unit is close to the fixing device from the layout of the image forming apparatus, the rise in internal temperature is suppressed to a very low level. Therefore, it is possible to avoid deterioration of the toner of the color developing device. Claim 3
According to the present invention, since the airflow of two paths is obtained without adding a fan, the configuration can be simplified and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a part of an internal mechanism of a full-color laser beam printer (LBP) which is an embodiment of an image forming apparatus of the present invention.

FIGS. 2A and 2B are diagrams showing a detailed structure of the duct of FIG. 1;

FIG. 3 is a sectional view taken along line A-A 'of FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Photoreceptor drum, 2 ... Charging charger, 3 ...
..Writing unit, 4 ... developing unit, 5 ... developing unit support, 6 ... intermediate transfer belt, 7 ...
Pre-cleaning charge, 8: Photoconductor cleaning unit, 9: Static eliminator, 10: Secondary transfer belt, 11: Cleaning unit, 12: Separation charger, 13: Transport means, 14 ... fixing device,
15 ... fan, 16 ... duct, 17 ... airflow, 18 ..., 19, 22, 23 ... opening, 2
0, 24: Partition plate, 21: Duct

Claims (3)

[Claims] A developing unit that forms a toner image on an image carrier; a fixing device that fixes the toner image on a transfer sheet;
In an electrophotographic image forming apparatus having a fan for sending an airflow for cooling the developing unit, an air cooling duct for passing an airflow from the fan is disposed in a space between the developing unit and the fixing device, An image forming apparatus, wherein two flow paths are formed in a duct for use. 2. A partition plate for partitioning the inside of the air cooling duct into two flow paths, wherein an air flow from the fan passes through the developing unit side and the fixing unit side in two layers. The image forming apparatus according to claim 1. 3. The air flow through each of the two flow paths using one fan.
An image forming apparatus according to claim 1.