JPH0934322A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To cool the inside of a device main body with air through simple and inexpensive constitution without being affected by external environment by forming an air passage partitioned with a device main body housing wall surface. SOLUTION: A casing 10 for the air flow passage is fitted to the external surface of a device main body housing substantially in contact. This casing 10 is open on both its end sides, i.e., facing the device main body housing and fans 11 and 12 which generate an air flow are installed in those open parts. Air made warm with the heat generated by a fixation unit 8, etc., is cooled while passing through an air outlet 13 and flowing in the casing 10 and put back into the device main body housing again from an air intake 4. Heat exchange with outside air through the external wall of the housing body 10 is easy, so natural heat radiation is effectively performed only by passing the air through the box body 10 installed outside the housing as compared with the circulation of air only in the device main body housing, thereby exhibiting cooling effect.

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 copying machine, a facsimile or a laser printer, which is provided with a structure for forcibly generating a flow of air inside a housing.

[0002]

2. Description of the Related Art For example, in an image forming apparatus utilizing an electrophotographic process, a corona discharger has been widely used to charge a photoreceptor. This corona discharger discharges a small-diameter metal wire by applying a high-voltage current to cause dielectric breakdown in the air around the wire. The wires used in the corona discharger are formed uniformly, but this is to prevent uneven discharge, and if they are not formed uniformly due to scratches or variations in wire diameter, there will be partial discharge unevenness. However, it is converted into a charging failure on the photoconductor. Such poor charging causes problems on the image. For example, there is a problem that black streaks occur in a portion that should be a white background.

Initial defects in wire parts are suppressed to such an extent that they do not become a serious problem due to the improvement of parts quality, etc. However, if stains adhere to the wires over time, similar discharge unevenness may occur. The cause of such contamination may be toner floating in the apparatus main body or various compounds generated when the wire is discharged. One of the causes of the generation of these compounds is that the substances contained in the air flown into the device body by a fan etc. for cooling the device body are oxidized by the ozone generated in the corona discharger. is there. The substances that flow in from outside the device body increase significantly due to chlorine contained in the tap water that vaporizes when a humidifier is used near the device, and in a dusty environment, the dust and the like flow in together. Reduce the device function.

Therefore, a structure has been proposed in which the heat generated in the main body of the apparatus is cooled without intruding such various compounds and fine dust from outside the main body of the apparatus. For example, Japanese Unexamined Patent Publication Nos. 64-59252 to 64-59256 are provided with a circulating air flow generating means for circulating an air flow in a housing through a heat source, and a cooling means having a cooling surface in the circulating air flow. It is disclosed that the circulation is repeated on the heat source side.

[0005]

In all of the above-mentioned conventional techniques, air is circulated in the main body of the apparatus. However, it is not easy to cool the circulating air,
The temperature inside the machine rises only by simply circulating it inside the apparatus body. Therefore, in the above-mentioned prior art, a forced cooling element is provided. That is, various heat exchangers,
An expensive unit must be installed. Therefore, in reality, the image forming apparatus does not employ a cooling circulation system.

In view of the above situation, it is an object of the present invention to provide an image forming apparatus capable of cooling the air inside the apparatus main body with a simple and inexpensive structure without being affected by the external environment.

[0007]

According to the present invention, in order to solve the above-mentioned problems, an image forming apparatus having an airflow generating means is provided with an air passage partitioned by a wall surface of the apparatus main body, At least a part of the airflow generated in the main body of the apparatus is configured to circulate through the air passage.

[0008]

In order to improve the cooling efficiency, it is preferable that the box defining the air passage is provided with an overhanging portion for heat dissipation.

Even if the air is not exchanged with the outside and the air is circulated only inside the apparatus, the paper dust generated in the machine,
The floating toner gradually increases. These dusts attach to the grease of the gear body of the apparatus, for example, to prevent smooth movement of the gear, or to fall on the image surface to adversely affect the image. . Therefore, in order to efficiently collect these dusts, it is convenient to provide a portion having an enlarged air passage cross section in the middle of the box defining the air passage.

Further, as described above, ozone is generated inside the machine due to corona discharge or the like in each charger, but in a structure in which air is not discharged to the outside of the machine, the influence of the ozone thus generated on the formed image is increased. Is a problem. Ozone is a very unstable substance, so its decomposition does not proceed at a relatively early stage and its concentration does not increase infinitely, but with the latest equipment with faster image formation processing speed,
The formation on the image is obvious. Therefore, it is preferable to provide ozone removing means in the middle of the box defining the air passage. In order to keep the ozone removal efficiency high, it is preferable that the ozone removal means is located on the upstream side of the air cooling area of the air passage. Further, in order to extend the life of the ozone removing means as much as possible, it is preferable that the ozone removing means is located on the downstream side of the air passage from the enlarged portion of the air passage cross section.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described based on an embodiment shown in the drawings. In FIG. 1, which is an exploded view of the configuration of an electrophotographic system as an example of the present invention, a charger 1
A latent image is optically formed on the surface of the photoconductor 2 charged by the corona discharge, and the latent image is developed into a visible image by the toner in the developing unit 3. The toner image formed on the photoconductor 3 is transferred by the transfer separation charger 5 to the recording paper that is conveyed by the registration roller 4 at the same timing, and is transferred to the fixing unit 8 by the transfer belt 6 and fixed on the recording paper. , Discharged outside the machine.

In these processes, each charger 1,
Ozone is generated at 5, and heat is generated at the fixing unit 8. In addition, heat is also generated in the PSU 7 which is an electrical system. If these heat and ozone are kept inside the machine, the device may not operate normally, and in the worst case, the device may be damaged. It was discharged outside. However, when heat or the like is discharged by using the fan, external air is taken in instead, so that it is greatly affected by the installation environment of the device.

In this embodiment, the air passage box body 10 is attached substantially in close contact with the outer surface of the main body of the apparatus (the back side of the housing in the illustrated example). Both ends of the box body 10, a portion facing the apparatus main body casing, are open to the casing, and the fan 1 for causing air circulation in these opening portions.
1 and 12 are installed. The box body 10 and the apparatus main body housing form an integrated closed space through both openings of the box body 10, the fans 11 and 12, the air discharge port 13 of the housing, and the air inlet 14.

When the fans 11 and 12 are driven to cause air to flow between the box body 10 and the apparatus main body casing (as shown in the drawing), the air heated by the heat generated in the fixing unit 8 or the like is It is cooled while passing through the box body 10, and is returned to the apparatus main body housing again from the air inlet 14. The space inside the box 10
Due to the double wall formed by the housing and the box, it is less likely to be affected by the heat generated in the main body of the apparatus, and moreover, the heat exchange with the outside air via the outer wall of the box is easy. Therefore, as compared with the case where the air circulates only inside the main body of the apparatus, by passing through the box installed outside the main body, natural heat dissipation is efficiently performed and the cooling effect is exhibited.

FIG. 2 shows a modified example of the box body for increasing the efficiency of natural heat dissipation. The internal air flow path of the box body 21 is divided by a plurality of ribs 22, and the air that has flowed into the box body from the main body of the apparatus through the air discharge port flows through any of the divided air flow paths. . On the outer surface of the box body 21, a heat radiating plate 23, which is a heat radiating overhang portion, is formed.
The heat of the air passing through the internal air flow path is easily conducted. In the illustrated example, the heat dissipation plate 23 is formed on the upper part of the box body, and heat is easily dissipated upward. As a material for the ribs and the heat dissipation plate, a metal having excellent thermal conductivity, such as aluminum, can be considered. However, a mold member may be used depending on the degree of cooling required.

The box shown in FIGS. 1 and 2 may be provided with a member for treating ozone generated in the charger of the apparatus body. As shown in FIG. 3, an ozone filter 25 is installed in the middle of the internal air flow path of the box 10. When the air containing ozone generated by the discharge of the charging charger or the like flows from the apparatus main body casing to the box body, the ozone is removed when passing through the ozone filter 25, and ozone-free air is returned into the casing. In order to enhance the cooling effect of the circulating air while ensuring the ozone removal efficiency, as shown in FIG. 4, the heat radiating plate 23 may be provided only in the downstream area of the air flow path from the ozone filter. Ozone is a structurally very unstable substance, and decomposition is promoted in a situation where heat energy is high. Therefore, the air that is warmed in the device body and contains ozone is
When the gas flows into the box, first, it passes through the filter in a state where it is easily decomposed, and then cooled, so that both ozone removal efficiency and cooling efficiency become suitable. Such a configuration is particularly useful for ensuring ozone removal efficiency when the ozone filter is of the catalytic type. High ozone removal efficiency means that the filter volume can be downsized, and it has advantages such as being able to suppress the increase in the air volume of the fan to cope with the pressure loss due to the ozone filter. Becomes

The dust and dust flying in the air has a small mass and
When the influence of the air velocity exceeds gravity,
Circulating air considering that it is often suspended
Fig. 5 shows an improved example in which these dusts and dirts are removed from
Shown in The box body 31 has a large change in its cross-sectional area on the way.
ing. In the narrowest air passage 32 and the widest passage 33
The air density, cross-sectional area and air velocity of each
ρ_A, V_A, S_AAnd ρ_B, V _B, S_BThen, the conservation of mass
By law ρ_AV_AS_A= Ρ_BV_BS_BBecomes Empty of the box 31
Since the air inflow opening and the outflow opening are substantially the same size,
Air velocity is inversely proportional to the cross-sectional area. Therefore,
If the cross-sectional area expands in the middle of the air flow path, the air velocity will decrease.
However, as a result of the reduced speed effect, dust and dirt contained in the air
Will sink due to gravity. Of the air flow path of the box
Below the air retention section 34, where the cross-sectional area expands, is shown in FIG.
So that the dust receiving pad 35 can be attached and removed freely.
If so, the inside of the box can be easily cleaned.

If the ozone filter 25 is installed downstream of the area of the passage 33 where dust and dirt settle in the air flow (FIG. 5), the air flows through the ozone filter after the dust and dirt are removed at the air retention portion. As a result, the amount of dust and dirt attached to the filter can be suppressed. The ozone filter is divided into small cells to remove ozone, and if the air passing through it contains dirt or dust, it clogs the cells and causes a decline in function, necessitating replacement or cleaning. However, according to this configuration in which dust and dirt are removed in advance, the life of the ozone filter can be extended, and it is not necessary to increase the fan performance in consideration of clogging of the ozone filter.

[0019]

According to the apparatus of the first aspect, the air passage partitioned by the wall surface of the apparatus body casing is formed, and at least a part of the airflow generated in the apparatus body circulates through the air passage. Therefore, it is possible to cool the air in the apparatus main body with a simple and inexpensive structure while reducing the influence from the external environment. If the structure for the air passage is provided on the outer side of the wall surface of the housing, it can be formed as an optional unit without being influenced by the internal structure of the apparatus. In the device according to the second aspect, since the box body that defines the air passage is provided with the overhanging portion for heat dissipation, it is possible to further enhance the cooling efficiency.

According to the third aspect of the present invention, since the box defining the air passage is provided with a portion where the cross section of the air passage expands in the middle of the box, the paper dust and floating toner generated inside the apparatus can be efficiently removed. You will be able to collect it.

According to the fourth aspect of the present invention, since the ozone removing means is provided in the middle of the box defining the air passage, not only the air cooling but also the adverse effect of ozone on the image formation can be avoided. it can. Moreover, as described in claim 5, if the ozone removing means is located on the upstream side of the air cooling region of the air passage, the efficiency of ozone removal can be maintained high. Further, as described in claim 6, if the ozone removing means is located on the downstream side of the air passage from the enlarged portion of the air passage cross section, the life of the ozone removing means can be extended as long as possible.

[Brief description of drawings]

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

FIG. 2 is a schematic view showing an improved example of a box for air circulation attached to an apparatus housing.

FIG. 3 is a schematic diagram illustrating how an ozone filter is attached to a box.

FIG. 4 is a partial schematic diagram illustrating a configuration in which a heat dissipation plate is provided on a downstream side of an air flow path with respect to an ozone filter.

FIG. 5 is a schematic view showing another modified example of the air circulation box.

FIG. 6 is a schematic diagram showing a configuration in which a dust receiving pad is attached to an air retaining portion of a box body.

[Explanation of symbols]

 1 Charging Charger 2 Photosensitive Member 3 Developing Unit 4 Registration Roller 5 Transfer Separation Roller 6 Conveyor Belt 7 PSU 8 Fixing Unit 10 Air Circulation Box 11, 12 Fan 13 Air Outlet 14 Air Inlet

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Toshiyuki Uchida 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd.

Claims (6)

[Claims] 1. An image forming apparatus having an air flow generating means in an apparatus main body, wherein an air passage partitioned by a wall surface of the apparatus main body casing is formed, and at least a part of the air flow generated in the apparatus main body passes through the air passage. An image forming apparatus characterized by circulating through. 2. The image forming apparatus according to claim 1, wherein the box defining the air passage is provided with an overhanging portion for heat dissipation. 3. In the middle of the box defining the air passage,
The image forming apparatus according to claim 1, further comprising a portion having an enlarged air passage section. 4. In the middle of the box defining the air passage,
4. An ozone removing means is provided, wherein the ozone removing means is provided.
The image forming apparatus according to claim 1. 5. The image forming apparatus according to claim 4, wherein the ozone removing unit is located upstream of the air cooling region of the air passage. 6. The image forming apparatus according to claim 4, wherein the ozone removing means is located on the downstream side of the air passage with respect to the enlarged portion of the air passage cross section.