JP2002357996A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate discomfort for a user by dispersing a temporary exhaustion of a large amount of heat or vapor from a fixing device. SOLUTION: In the apparatus, forced circulation is generated in flow paths of generated heat or vapor only immediately before a fixing process for transfer material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus using an electrophotographic system, such as a printer for a computer or a copying machine.

[0002]

2. Description of the Related Art In an image forming apparatus using an electrophotographic system, for example, an electrostatic latent image is formed on a surface of a photosensitive drum as an image carrier, and the electrostatic latent image on the photosensitive drum is used as a developer. It is developed with a toner or the like to form a visible image. The developed image is transferred onto a transfer material by a transfer device to carry the image, and the toner image on the transfer material is fixed on the transfer material by a fixing device using pressure, heat, or the like. An image is formed by performing these steps.

[0003] Advances in technology have led to fixing devices being located just inside the exterior of the image forming apparatus in order to further reduce the size of the apparatus. Further, as the image forming speed is increased, the fixing temperature tends to be increased in order to secure the fixing property.

[0004]

However, as the above-mentioned conventional image forming apparatus has been downsized and the fixing temperature has been increased, the exhaust heat and hot air in the image fixing step have given a user discomfort.

[0005] In the fixing step, since the heat capacity of the transfer material is large, a heater or the like is turned on to compensate for the amount of heat to sufficiently secure the image fixing property. A large amount of the surplus heat is discharged outside the image forming apparatus.

In addition, when the fixing device melts and fixes the developer, the water contained in the transfer material and the developer becomes steam and is discharged out of the image forming apparatus.

[0007] When these heat and water vapor are discharged by natural convection, they are relatively not diffused. Therefore, if they touch the user as it is, the user will feel uncomfortable. FIG.
As shown in (2), heat and steam generated near the transfer material conveyance downstream of the fixing device 8 are discharged in the directions of the arrows of the flows f3 and f4.

Accordingly, an object of the present invention is to prevent heat and water vapor from causing discomfort to the user without sacrificing the functions of the image forming apparatus and the slimness of the apparatus.

[0009]

According to the invention of the present application, the above object is achieved by the following constitution.

In a print job of an image forming apparatus, a large amount of heat or water vapor is generated immediately after the step of fixing development onto a transfer material. Further, the conventional air flow path is always in one direction when operating, regardless of whether the air flow is in standby or during printing.

In the present invention, the air flow path is changed for a certain period during a print job. Or, it is designed to flow backward in the changed direction.

For example, only immediately after the fixing step, air is taken in or exhausted from the heat / water vapor source. This action diffuses heat and water vapor.

As a result, it is possible to make the hot air or steam come into direct contact with the user or to make the steam so thin that the steam cannot be seen.

[0014]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

(First Embodiment) A first embodiment of the present invention will be described with reference to FIGS.

FIG. 1 shows a schematic configuration diagram of an image forming apparatus using an electrophotographic method according to the present embodiment. The image forming apparatus is a laser beam printer that can form a four-color full-color image.

An image forming apparatus A for forming an image by fixing an image visualized by a developer onto a transfer material by heat is a drum-type electrophotographic photosensitive member as a first image carrier. The photosensitive drum 1 is provided. The photosensitive drum 1 is driven to rotate, for example, counterclockwise by driving means (not shown).

A charging device 2 for uniformly charging the surface of the photosensitive drum 1 in order according to the rotation direction of the photosensitive drum 1 around the photosensitive drum 1 is irradiated with a laser beam based on image information. Developing device 4 for forming an electrostatic latent image on the photosensitive drum 1, developing device 4 for attaching the toner image on photosensitive drum 1 to develop as a toner image, second image carrier on which the toner image on photosensitive drum 1 is primarily transferred A transfer unit 5, a cleaning device 6 for removing transfer residual toner remaining on the surface of the photosensitive drum 1 after the primary transfer, and the like are provided.

The developing device 4 for developing the electrostatic latent image on the photosensitive drum 1 has four developer containing portions 4BK, 4Y, 4M, 4C for containing four color toners. 4BK, 4Y, 4M, and 4C are arranged concentrically around the rotation center 4a. Each developer container 4BK, 4
Y, 4M, and 4C are provided with a developer carrying roller 4b that carries a toner as a developer on the surface and faces the photosensitive drum 1 when the developer accommodating portion faces the photosensitive drum 1. The electrostatic latent image on the photosensitive drum 1 can be developed by the developer carrying roller 4b.

The transfer unit 5, which is the second image carrier,
After the primary transfer of the toner image on the photosensitive drum 1, secondary transfer can be performed on the surface of the transfer material S fed toward the transfer unit 5. The transfer material S is transported from the cassette to the transfer unit 5 at a predetermined timing by a feeding / transporting unit.

Further, the image forming apparatus A is provided with a fixing device 8 for heating the toner on the transfer material S after the secondary transfer to fix the toner image on the transfer material S. The transfer material S that has passed through the fixing device 8 is transported by the transport unit 9 to the discharge tray 1.
Discharged to zero. The fixing device 8 includes a pair of rotating members, that is, a fixing roller 8b and a pressure roller 8a.
When the surface of the fixing roller 8b is heated to a predetermined temperature by a heater (not shown) in the fixing roller 8b, the transfer material S carrying the toner image is passed between the fixing roller 8b and the pressing roller 8a. The toner image is fixed on the transfer material S by heating or pressing the transfer material S.

In the image forming apparatus, a fixing device 8 having a heater therein is used as a heat source. Conventionally, heat or water vapor generated from a fixing device rises by natural convection as it is and is discharged outside the image forming apparatus.

In this embodiment, as shown in FIGS. 2 and 3 which are perspective views, a part of the duct 20 is provided with an opening door 21 which can be opened and closed. Normally, the opening door 21 is closed as shown in FIG. However, only when a large amount of heat or water vapor is generated as a result of the fixing step performed on the transfer material, for example, as shown in FIG. Opens. Then, forced convection is generated in a flow path of a large amount of heat and water vapor, which causes diffusion and discharge to the outside of the image forming apparatus, or capture in the image forming apparatus.

(Second Embodiment) A second embodiment of the present invention
This will be described with reference to FIGS.

In the illustrated example, the fan 19 exhausts air outside the apparatus in a normal state during operation of the image forming apparatus. At this time, the opening door 24 is in close contact with the duct 25 due to the negative pressure. Only when a large amount of heat or water vapor is generated by performing the fixing process on the transfer material, the fan 19 rotates in the reverse
The pressure in the duct 25 increases. Due to the pressure, the opening door 24 naturally rotates around the fulcrum 23 as shown in FIG. Then, forced convection is generated in the flow path of a large amount of heat and water vapor, causing diffusion and discharge to the outside of the image forming apparatus.

Further, the opening door may be closed when the fan 19 is in the normal state and the air is in the intake state, and the opening door 24 may be opened inside by the exhaust air only immediately after the fixing process.

[0027]

As described above, according to the invention of the present application, an opening formed by an openable and closable door in an existing air flow path is appropriately used to temporarily generate heat from a heat source. Water vapor can be effectively discharged.

As a result, the size of the apparatus can be reduced,
In addition, the user does not feel uncomfortable.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram illustrating an image forming apparatus of the present invention.

FIG. 2 is a partial perspective view showing a first embodiment of the present invention.

FIG. 3 is a partial perspective view showing a first embodiment of the present invention.

FIG. 4 is a partial sectional view showing a second embodiment of the present invention.

FIG. 5 is a partial sectional view showing a second embodiment of the present invention.

FIG. 6 is a partial sectional view showing a conventional air flow path.

FIG. 7 is a partial side view showing a conventional air flow path.

[Explanation of symbols]

 8 Fixing device (heat source) 19 Fan (forced convection means) 20, 25 Duct 21, 24 Opening door 22, 23 Support point

Claims (3)

[Claims] 1. An image forming apparatus according to claim 1, wherein a duct shape is temporarily changed in an image forming process and an air flow path is changed in an image forming apparatus having an air flow path separated by a duct or the like. 2. An image forming apparatus in which an image is obtained by a fixing device having a heat source such as a heater, wherein a duct shape is temporarily changed in association with a fixing process, and an air flow path is changed. Item 2. The image forming apparatus according to Item 1. 3. In an image forming apparatus having a forced convection device such as a fan in an air flow path, the air flow path can be changed by a change in air pressure when the forced convection device performs reverse rotation in an image forming process. 3. The image forming apparatus according to claim 2, wherein the image forming apparatus is capable of performing the following.