JP2007233280A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To present optimum air flow constitution that removes ozone and prevents image defects, while averting noise and size increase of an apparatus. <P>SOLUTION: An air discharging means of discharging air from an image formation section, equipped with a charging device, is provided with pluralities of ozone filters and fans in series; and a first fan which is arranged upstream has higher static pressure characteristics than a second fan, and the first fan is arranged downstream and is arranged adjacent to the image formation section. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus such as an electrophotographic copying machine and an electrostatic recording apparatus, and more particularly to an improvement in air flow in the image forming apparatus.

  In an image forming unit such as a copying machine or a printer using an electrophotographic system, a toner image is formed in a developing process after an electrostatic latent image is formed on the surface of a photoreceptor. The toner image on the photoconductor is directly transferred from the photoconductor to a recording material or transferred via an intermediate transfer body, and a toner image is formed on the recording material. In order to form an electrostatic latent image on the photoconductor or to control the charge of the toner image on the photoconductor or intermediate transfer body, a charger is used to perform a charging / discharging process.

  A corona charger is generally used as a charger used in the image forming unit, but it is known that a discharge product typified by ozone or nitrogen oxide is generated by corona discharge. If the discharge generating substance stays in the discharge device, the discharge of the discharge device becomes unstable, causing uneven charging and neutralization, thereby reducing the image quality of the toner image formed on the surface of the image carrier. Further, the staying discharge product may adversely affect the surface of the image carrier, causing image blurring or reducing the life of the image carrier.

  Therefore, in order to prevent such a discharge product from staying in the discharge device, an exhaust fan is installed to discharge the air in the discharge device to the outside of the apparatus. In this case, if the discharge product concentration remains high, environmental problems such as off-flavors will occur. Therefore, a means for removing these substances through an ozone filter or the like is used. The discharge product is removed by the action of activated carbon or a catalyst contained in the filter, and is discharged to the outside after the concentration is lowered to a level where there is no problem.

When the amount of ozone generated in the image forming unit is large, it is known that a plurality of exhaust fans and filters are provided and arranged in series to avoid the increase in size of the apparatus while ensuring the ozone removal performance. . (See Patent Document 1).
JP-A-871317

  However, in the above conventional example, as described below, there is a problem that an exhaust air amount necessary for the image forming unit cannot be secured and an image defect occurs.

  In general, in the air flow of the image forming unit, it is important to sufficiently supply and exhaust air to the primary charger that uniformly charges the surface of the photosensitive drum. This is because when a discharge product typified by nitrogen oxides generated by the primary charger or toner scattered from the developing device adheres to the charging wire or grid of the primary charger, the image easily deteriorates. . For this reason, fresh air is supplied from the outside to the primary charger, and a duct is provided adjacent to the primary charger to reliably collect the air discharged from the primary charger.

  However, it may be difficult to ensure a sufficient amount of exhaust air from the primary charger. Generally, a drive system configuration for driving image forming means such as a photosensitive drum, a developing sleeve, and a cleaner screw, and the above-described airflow configuration are provided adjacent to the image forming unit around the image forming unit. In a case where the image forming unit is configured to be pulled out to the front of the apparatus for maintenance, it is common to provide an air supply configuration above the image forming unit and provide a drive configuration and an exhaust configuration behind the image forming unit. The exhaust structure is composed of a duct, a fan, and a filter. However, the exhaust duct is usually disposed in an excess space of the drive structure, and the shape is often complicated and the flow path is often narrowed. As a result, the flow path resistance is increased, and it is difficult to secure a necessary air volume.

  The above-mentioned conventional example reduces ozone step by step by providing a plurality of fans and filters, and although effective for removing ozone, for securing the necessary air volume in the image forming unit, Not enough measures are taken. For this reason, there is a concern that an image defect occurs due to contamination of the primary charger.

  Of course, if the fan capacity is simply increased to increase the air volume, noise will increase and the fan size will increase, resulting in a problem of increasing the size of the apparatus.

  The present invention has been made in view of the above problems, and its object is to provide an optimal airflow configuration that prevents ozone and the occurrence of image defects while avoiding noise and an increase in size of the apparatus. It is in.

In an image forming apparatus comprising: an image carrier that carries an image on its surface; and an image forming unit that has a charger for charging or discharging the image carrier.
The exhaust unit for discharging the air of the image forming unit includes a plurality of ozone filters and a fan in series, and the first fan disposed on the upstream side is more than the second fan disposed on the downstream side. It has high static pressure characteristics, and the first fan is arranged adjacent to the image forming unit.

  According to the first aspect of the present invention, in the image forming apparatus comprising: an image bearing member that carries an image on the surface; and an image forming unit that includes a charger for charging or discharging on the image bearing member. The exhaust means for exhausting the air includes a plurality of ozone filters and fans in series, and the first fan disposed on the upstream side has a higher static pressure than the second fan disposed on the downstream side. Since the first fan is disposed adjacent to the image forming unit and has a characteristic, the shape of the exhaust duct inside the image forming unit is complicated and the flow path is narrowed. Even if the resistance becomes high, a fan with high static pressure characteristics can be placed near the image forming unit to ensure the necessary air volume in the image forming unit, thereby preventing image defects. It becomes possible to prevent

  Moreover, since a plurality of ozone filters are used, ozone removal can be performed reliably and efficiently. Further, since the size of the single fan can be reduced by using a plurality of fans, it is possible to avoid an increase in the size of the apparatus main body. In general, a fan with high static pressure characteristics is louder than a fan with low static pressure characteristics, but the fluid noise generated by the fan flows out of the machine by disposing a relatively loud first fan on the upstream side. This makes it difficult to reduce noise.

  According to a second aspect of the present invention, the exhaust means for discharging the air of the image forming unit is configured by a duct and a closed space in the main body as an exhaust path, and an electric substrate is disposed in the closed space in the main body, Since the ozone filter is arranged further downstream, the exhaust air is heated by heat radiation from the electric substrate, and the ozone removal rate in the ozone filter can be improved. This utilizes the characteristic of the ozone filter that the higher the temperature, the higher the ozone removal rate. By improving the ozone removal rate, the ozone concentration discharged to the outside of the machine can be reduced, and a more environmentally friendly product can be provided.

  Next, details of the present invention will be described in accordance with the description of the embodiments.

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

  FIG. 2 is a cross-sectional view of a one-drum intermediate transfer belt type color image forming apparatus. The configuration and operation will be described below.

  A photosensitive drum 1 as an image carrier is rotatably provided, and a primary charger 2 is disposed above the photosensitive drum 1 to uniformly charge the surface of the photosensitive drum. The laser unit 3 as writing means selectively exposes the surface of the photosensitive drum 1 according to the image signal, and an electrostatic latent image is formed.

  The developing device 4 on the left side of the photosensitive drum 1 visualizes the electrostatic latent image with toner. The developing device 4 includes four developing devices 5Y, 5M, 5C, and 5K that include toners of colors of yellow, magenta, cyan, and black. Developing devices 5Y, 5M, 5C, and 5K mounted on the rotary developing device 6 sequentially face the photosensitive drum 1 and perform a developing process.

  Below the photosensitive drum 1 is an intermediate transfer belt 7 which is an intermediate transfer member. By sequentially transferring the toner images visualized by the developing devices of the respective colors at the primary transfer portion T1, a toner image that has been multiplex-transferred on the surface of the intermediate transfer belt 7 is obtained.

  The recording material P is fed from the paper feeding unit to the registration roller 8. The recording material P waiting on the registration roller 8 is sent to the secondary transfer portion T2 in synchronization with the toner image on the intermediate transfer belt 7.

  The secondary transfer roller 9 as a secondary transfer unit is configured to be able to contact and separate from the intermediate transfer belt 7, and is separated when the multiple transfer process is performed on the intermediate transfer belt 7. When performing the process, contact. The toner image is transferred onto the recording material P at the secondary transfer portion T2.

  The toner image carried on the recording material is fixed to the recording material P by heat and pressure in the fixing device 10, and image formation on the recording material is completed.

  On the other hand, the photosensitive drum 1 is provided with a drum cleaner 11, and the intermediate transfer belt 7 is provided with a transfer cleaner 12. Both of these are blade cleaning systems. The drum cleaner 11 cleans untransferred toner remaining on the photoreceptor in the primary transfer process. The transfer cleaner 12 is configured to be able to contact and separate from the intermediate transfer belt 7 and cleans untransferred toner remaining on the intermediate transfer belt 7 in the secondary transfer process.

  FIG. 1 is a diagram showing an air flow configuration of an ozone treatment system, and is a top view of the apparatus main body. An airflow configuration around the primary charger will be described with reference to FIGS. 1 and 2. An air supply duct 31 is provided above the primary charger 2, and fresh air is supplied to the primary charger 2 from the outside via a dustproof filter 31a and an air supply fan 31b. An exhaust duct 32 is provided on the left side of the primary charger 2 and exhausts chemical substances such as ozone generated from the primary charger 2. These ducts are provided with openings in the longitudinal direction of the primary charger 2 so as to uniformly supply and exhaust air over the entire area in the thrust direction with respect to the primary charger 2. Behind the exhaust duct 32 is a process kit rear side plate 33 which is a support member of the image forming unit, and the process kit rear side plate 33 is provided with a duct portion 33a for relaying exhaust air. Behind the process kit rear side plate 33 is a main body rear side plate 34 which is a main frame of the image forming apparatus main body. An exhaust unit 35 is disposed on the rear side of the main body rear plate 34. The exhaust unit 35 includes a sirocco fan 36 having high static pressure characteristics, a toner filter 37 that collects scattered toner from the image forming unit, and an ozone filter 38. By operating the sirocco fan 36, the air inside and around the primary charger 2 is sucked into the exhaust unit 35 via the exhaust duct 32 and the relay duct portion 33a. Inside the exhaust unit 35, air passes through the toner filter 37, the ozone filter 38, and the sirocco fan 36 in this order, and is discharged to a duct unit downstream of the exhaust unit 35.

  FIG. 3 is a perspective view showing an airflow configuration behind the primary charger. A bearing 33b for driving and supporting the photosensitive drum 1 is fixed to the rear plate 33 of the process kit, and an opening 33c for a developing sleeve driving unit (not shown) and a cleaner screw driving unit (not shown). An opening 33d for a high voltage supply unit (not shown) to the primary charger is provided. The exhaust duct 32 provided on the left side of the primary charger 2 is connected through an opening 33f, and the exhaust unit 35 is connected through an opening 33g. The duct portion 33a for relaying the exhaust air provided on the rear plate 33 of the process kit is disposed in a surplus space such as a drive configuration for driving these image forming means and a high-voltage power feeding portion, and has a complicated shape and a flow path. Tends to narrow.

  Therefore, although the flow path resistance is large, the necessary air volume in the image forming unit is reliably ensured by arranging the sirocco fan 36 having high static pressure characteristics in the vicinity thereof.

  An airflow configuration downstream of the exhaust unit 35 will be described with reference to FIG. A fan 46 and a filter 47 are further provided downstream of the exhaust unit 35. Here, the reason for providing a plurality of sets of fans and filters instead of one set in the apparatus is that if ozone discharge is large, if ozone removal is performed with one set of fans and filters, the ozone filter and fan This is because a large size is required, and as a result, the size of the apparatus tends to increase. In other words, because the mounting density of parts and units is high in the image forming unit and its vicinity in the main body of the apparatus, it is farther away from the vicinity of the image forming unit than arranging a large fan and filter near the image forming unit As a result, it is possible to reduce the size of the apparatus body.

  A duct 39 is provided downstream of the exhaust unit 35 to guide air from the outside of the main body rear side plate to the inside. The air from the duct 39 is discharged into the main body closed space 43 surrounded by the front and rear main body side plates 40 and 34, the stay 41 and the outer cover 42 above the image forming unit and the fixing device. An electric substrate 44 is disposed on the stay 41. A second exhaust unit 45 is provided on the left side of the electric substrate 44 and includes an axial fan 46 and an ozone filter 47.

  The air discharged from the duct 39 into the closed space 43 in the main body passes through the ozone filter 47 and the exhaust port 48 by the action of the axial fan 46 and is discharged outside the apparatus. The air inside the body closed space 43 is heated by receiving heat from the electric substrate 44 and the fixing device 10. For this reason, the temperature of the 2nd ozone filter 47 also becomes high, and the improvement of the removal rate of ozone is achieved.

  In the sirocco fan 36 and the axial fan 46, the sirocco fan 36 generates a louder sound. However, a relatively noisy sirocco fan is disposed inside the apparatus, and an axial fan having a relatively low noise is provided. Since it is disposed on the exhaust port side of the apparatus main body, the fluid sound generated from the sirocco fan is difficult to leak out of the apparatus, and noise can be reduced.

  As described above, by applying the present invention, it is possible to achieve an optimal airflow configuration that prevents ozone and the occurrence of image defects while avoiding noise and enlargement of the apparatus.

The upper view of the apparatus main body which shows the airflow structure of the ozone treatment type | system | group in embodiment of this invention. 1 is a cross-sectional view of a one-drum intermediate transfer belt type color image forming apparatus according to an embodiment of the present invention. The perspective view which shows the airflow structure of the back of the primary charger in embodiment of this invention.

Explanation of symbols

1 Photosensitive drum 2 Primary charger 36 Sirocco fan 38 Ozone filter,
46 Axial fan 47 Ozone filter 43 Closed body 44 Electrical board

Claims (2)

In an image forming apparatus comprising: an image carrier that carries an image on its surface; and an image forming unit that has a charger for charging or discharging the image carrier.
The exhaust unit for discharging the air of the image forming unit includes a plurality of ozone filters and a fan in series, and the first fan disposed on the upstream side is more than the second fan disposed on the downstream side. An image forming apparatus having high static pressure characteristics and having a first fan disposed adjacent to an image forming unit.   The exhaust means for discharging the air of the image forming unit is configured by a duct and a closed space in the main body as an exhaust path, an electric substrate is disposed in the closed space in the main body, and an ozone filter is disposed downstream of the electric substrate. The image forming apparatus according to claim 1.

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