Image forming apparatus with branched ducts for cooling of image forming units

An image forming apparatus includes a first image forming unit, a second image forming unit, and an intake unit. The intake unit includes an intake duct provided at one side relative to the first and the second image forming units in an arrangement direction of the plurality of image forming units and configured to take in air outside the image forming apparatus from an intake port, a first fan configured to take in air from a first communication port, and a second fan configured to take in air from a second communication port. The intake unit branches air taken in from the intake duct to the air taken in from the first communication port by the first fan and the air taken in from the second communication port by the second fan, and blows the air to each of the first image forming unit and the second image forming unit.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to an image forming apparatus such as a printer, a copier, a facsimile, or a multifunction peripheral.

Description of the Related Art

In an image forming apparatus, a toner image is formed on an image bearing member such as a photosensitive drum or an intermediate transfer belt, the toner image is transferred from the image bearing member to a recording material, and then heat and pressure are applied by a fixing unit to fix the toner image on the recording material. In such an image forming apparatus that forms an image on a recording material using toner, a developing unit that develops an electrostatic latent image of the image bearing member using the toner is provided. The developing unit accommodates the toner therein, and circulates and conveys the toner while stirring the toner by a conveying screw in the developing unit. Therefore, the developing unit generates heat in response to a toner stirring operation. As described above, a plurality of units that generates heat, such as the fixing unit and the developing unit, are provided inside the image forming apparatus.

Therefore, conventionally, a configuration has been proposed in which a plurality of cooling targets such as a fixing unit and a developing unit are cooled by outside air taken in from an intake port by an intake fan (Japanese Patent Application Laid-Open No. 2010-32780). In the device described in Japanese Patent Application Laid-Open No. 2010-32780, in order to efficiently blow air to each of the plurality of cooling targets, a plurality of fans is provided, and ducts connecting the fans from the intake ports are provided for the number of fans. In this case, each of the plurality of cooling targets can be efficiently cooled.

Meanwhile, an image forming apparatus that forms an image on a recording material using toners of a plurality of colors includes a plurality of image forming units (also referred to as image forming stations) that form toner images of respective colors on a photosensitive drum for each color. In the case of including a plurality of image forming units, it is necessary to cool each cooling target included in each image forming unit. In this case, as in the device described in Japanese Patent Application Laid-Open No. 2010-32780, when the plurality of ducts is provided for connecting the fan from the intake port for each of a plurality of cooling targets, a sufficient air blowing amount to each cooling target can be secured, but an area occupied by the ducts increases in the image forming apparatus. Therefore, conventionally, in order to secure a space for individually disposing the fan and the duct for each of the plurality of units, it is necessary to increase the size of the device. However, this goes against a recent demand for miniaturization of the device, and thus it is difficult to adopt the device.

In view of the above problems, there is need for providing an image forming apparatus capable of suppressing an increase in size of the apparatus and guiding outside air taken in by an intake fan with a sufficient air blowing amount secured when the outside air is guided toward a plurality of units via ducts.

SUMMARY OF THE INVENTION

According to a first aspect of the present invention, an image forming apparatus configured to form an image on a recording material includes a first image forming unit among a plurality of image forming units, the first image forming unit having a first photosensitive member, a first charging unit configured to charge the first photosensitive member by corona discharge, and a first developing unit configured to develop an electrostatic latent image formed on the first photosensitive member using toner, a second image forming unit among the plurality of image forming units, the second image forming unit having a second photosensitive member, a second charging unit configured to charge the second photosensitive member by corona discharge, and a second developing unit configured to develop an electrostatic latent image formed on the second photosensitive member using toner, and an intake unit including an intake duct provided at one side relative to the first and the second image forming units in an arrangement direction of the plurality of image forming units and configured to take in air outside the image forming apparatus from an intake port, a first fan configured to take in air from a first communication port formed in a first side surface portion of the intake duct, and a second fan configured to take in air from a second communication port formed in a second side surface portion facing the first side surface portion of the intake duct. The intake unit is configured to branch air in the intake duct to the air taken in from the first communication port by the first fan and the air taken in from the second communication port by the second fan, and blow the air to each of the first image forming unit and the second image forming unit.

DESCRIPTION OF THE EMBODIMENTS

Image Forming System

A schematic configuration of an image forming system including an image forming apparatus of the present embodiment will be described with reference toFIG.1. An image forming system1X illustrated inFIG.1includes an image forming apparatus100and a finisher device300. The image forming apparatus100and the finisher device300are connected so as to be able to transfer a recording material S. In the present embodiment, the finisher device300is a post-process unit that can be retrofitted to the image forming apparatus100for function enhancement, and can perform a post-process to be described below on the recording material S on which a toner image is fixed by the image forming apparatus100. The image forming apparatus100and the finisher device300are connected to each other to be able to transmit and receive data therebetween through a communication interface capable of serial communication and parallel communication.

Image Forming Apparatus

The image forming apparatus100is an electrophotographic tandem full-color printer, and includes a first casing101aand a second casing101b. In the first casing101a, various devices such as an image forming unit700that realizes a process of conveying the recording material S and transferring the toner image, various members, and the like are disposed.

Meanwhile, in the second casing101b, various devices such as a fixing unit800that realizes a process of conveying the recording material S and fixing the toner image, various members, and the like are disposed. In addition, the second casing101bis provided with an operation unit200having a display unit capable of displaying various types of information on the front side, a key capable of inputting various types of information according to a user operation, and the like. An electric unit (not illustrated) having a power supply board may be disposed on the back side of the first casing101aand the second casing101b. In the present specification, in order to operate the image forming apparatus100by the user, a side on which a user stands when operating the operation unit200is referred to as a “front surface”, and an opposite side thereof is referred to as a “back surface”. In addition, a side surface on a left side when viewed from the front is referred to as a “left surface”, and a side surface on the right side when viewed from the front is referred to as a “right surface”.

The image forming apparatus100includes image forming portions Pa, Pb, Pc, and Pd that form yellow, magenta, cyan, and black images, respectively. The image forming apparatus100forms a toner image on the recording material S according to an image signal received from an external device (not illustrated) such as the document reading apparatus190or a personal computer that reads an image signal from a document.

In the case of the present embodiment, the image forming portions Pa to Pd, primary transfer rollers24ato24d, an intermediate transfer belt130, plurality of rollers13to15, and a secondary transfer outer roller11constitute an image forming unit700that forms a toner image on the recording material S. Examples of the recording material S include paper such as plain paper, thick paper, rough paper, uneven paper, and coated paper, a plastic film, cloth, and the like.

As illustrated inFIG.1, the image forming portions Pa to Pd are arranged side by side along a moving direction of the intermediate transfer belt130. The intermediate transfer belt130is stretched around the plurality of rollers13,14, and15and moved in a direction of an arrow R2. Then, the intermediate transfer belt130carries and conveys a toner image to be primarily transferred as described below. The secondary transfer outer roller11is disposed at a position interposed between the secondary transfer inner roller14stretching the intermediate transfer belt130and the intermediate transfer belt130to face the secondary transfer inner roller14and the intermediate transfer belt130, and forms a secondary transfer portion T2that transfers the toner image on the intermediate transfer belt130to the recording material S. A fixing unit800is disposed downstream of the secondary transfer portion T2in a recording material conveyance direction.

On the lower side of the image forming apparatus100, a plurality of (here, two) cassettes10in which recording materials S are accommodated are arranged. The recording materials S having different sizes and thicknesses are accommodated in the cassettes10, and the recording material S is selectively conveyed from one of the cassettes10. The recording material S is conveyed from the cassette10toward a registration roller12through a conveying path by a conveying roller16. Thereafter, the registration roller12rotates in synchronization with the toner image formed on the intermediate transfer belt130, whereby the recording material S is conveyed toward the secondary transfer portion T2. Note that the recording material S is not limited to the recording material S stored in the cassette10, and the recording material S placed on a manual feed unit (not illustrated) may be conveyed.

The image forming portions Pa, Pb, Pc, and Pd have substantially the same configuration except that developed colors of the toner images are different. Therefore, here, the yellow image forming portion Pa will be described as a representative, and description of the other image forming portions Pb, Pc, and Pd will be omitted.

In the image forming portion Pa, a cylindrical photosensitive drum3ais disposed as a photosensitive member. The photosensitive drum3ais rotationally driven by a motor (not illustrated). A charging unit2a, an exposing unit La, a developing unit1a, the primary transfer roller24a, and a drum cleaning unit4aare disposed around the photosensitive drum3a. In the present embodiment, the image forming portion Pa is an example of a first image forming unit which is one of a plurality of image forming units. The image forming portion Pa includes the photosensitive drum3awhich is an example of a first photosensitive member, the charging unit2awhich is an example of a first charging unit that charges the photosensitive drum3aby corona discharge, and the developing unit1awhich is an example of a first developing unit that develops an electrostatic latent image formed on the photosensitive drum3ausing toner. In the present embodiment, the image forming portion Pb is an example of a third image forming unit which is one of the plurality of image forming units. The image forming portion Pb includes a photosensitive drum3bthat is an example of the third photosensitive member, a charging unit2bthat is an example of a third charging unit that charges the photosensitive drum3bby corona discharge, and a developing unit1bthat is an example of a third developing unit that develops an electrostatic latent image formed on the photosensitive drum3busing toner. In the present embodiment, the image forming portion Pc is an example of a fourth image forming unit which is one of the plurality of image forming units. The image forming portion Pc includes a photosensitive drum3cwhich is an example of a fourth photosensitive member, a charging unit2cwhich is an example of a fourth charging unit that charges the photosensitive drum3cby corona discharge, and a developing unit1cwhich is an example of a fourth developing unit that develops an electrostatic latent image formed on the photosensitive drum3cusing toner. In the present embodiment, the image forming portion Pd is an example of a second image forming unit which is one of the plurality of image forming units. The image forming portion Pd includes a photosensitive drum3dwhich is an example of a second photosensitive member, a charging unit2dwhich is an example of a second charging unit that charges the photosensitive drum3dby corona discharge, and a developing unit1dwhich is an example of a second developing unit that develops an electrostatic latent image formed on the photosensitive drum3dusing toner.

For example, a process of forming a full-color image by the image forming apparatus100will be described. First, when the image forming operation is started, the surface of the rotating photosensitive drum3ais uniformly charged by the charging unit2a. The charging unit2ais, for example, a corona charger that irradiates charged particles associated with corona discharge to charge the surface of the photosensitive drum3ato a uniform potential. Next, the photosensitive drum3ais scanned and exposed by a laser beam corresponding to an image signal emitted from the exposing unit La. As a result, an electrostatic latent image corresponding to the image signal is formed on the surface of the photosensitive drum3a. The electrostatic latent image formed on the photosensitive drum3ais developed into a toner image that is a visible image by a developer containing toner and a carrier stored in the developing unit1a. In other words, the toner image is developed on the photosensitive drum3aby the toner supplied by the developing unit1a. In the developing units1ato1d, the developer is circularly conveyed while being stirred by a conveying screw (not illustrated).

The toner image formed on the photosensitive drum3ais primarily transferred to the intermediate transfer belt130at a primary transfer portion T1configured between the primary transfer roller24aand the photosensitive drum3a, the primary transfer roller24abeing disposed with the intermediate transfer belt130interposed therebetween. At this time, a primary transfer voltage is applied to the primary transfer roller24a. The toner remaining on the surface of the photosensitive drum3aafter the primary transfer is removed by the drum cleaning unit4a.

Such an operation is sequentially performed in the yellow, magenta, cyan, and black image forming portions Pa to Pd, and toner images of four colors are superimposed on the intermediate transfer belt130. Thereafter, the recording material S accommodated in the cassette10is conveyed to the secondary transfer portion T2in accordance with the formation timing of the toner image. Then, by applying a secondary transfer voltage to the secondary transfer outer roller11, the full-color toner images formed on the intermediate transfer belt130are secondarily transferred collectively to the recording material S. The toner remaining on the intermediate transfer belt130after the secondary transfer is removed by a belt cleaning unit (not illustrated).

In the present embodiment, the photosensitive drum3acorresponds to the first photosensitive member, and the photosensitive drums3b,3c, and3dcorrespond to the second photosensitive members. The developing unit1acorresponds to a first developing unit, and the developing units1b,1c, and1dcorrespond to second developing units.

The recording material S to which the toner image has been transferred is conveyed to the fixing unit800. The fixing unit800fixes the toner image on the recording material S by applying heat and pressure to the recording material S to which the toner image has been transferred. In the case of the present embodiment, it is possible to selectively apply heat and pressure to the recording material S by a first fixing device81and then further apply heat and pressure by a second fixing device91. In the fixing unit800, whether the recording material S is conveyed toward the second fixing device91after passing through the first fixing device81or is conveyed while avoiding the second fixing device91after passing through the first fixing device81is switched by a fixing switching member95.

The second fixing device91is disposed on the downstream of the first fixing device81in the conveyance direction of the recording material S. The second fixing device91is selectively used for the purpose of further adding gloss to the toner image on the recording material S fixed by the first fixing device81. For example, in a case where the recording material S is coated paper such as glossy paper or synthetic paper, the recording material S having passed through the first fixing device81is conveyed along a fixing route30aso that fixing is performed by both the first fixing device81and the second fixing device91. Meanwhile, in a case where the recording material S is non-coated paper such as plain paper, the recording material S having passed through the first fixing device81is conveyed along a fixing-by-pass route30bavoiding the second fixing device91so that the fixing is not performed in the second fixing device91while the fixing is performed in the first fixing device81.

Since the first fixing device81and the second fixing device91may have the same configuration, the first fixing device81will be described as an example. The first fixing device81includes a fixing roller82(or a fixing belt) that is rotatable in contact with a surface of the recording material S on which the toner image is fixed, and a pressure belt83(or a pressure roller) that is pressed against the fixing roller82to form a fixing nip portion. At least one of the fixing roller82and the pressure belt83is heated by a heater (not illustrated). The first fixing device81applies heat and pressure to the recording material S at the time of nipping and conveying the recording material S on which the toner image is formed in the fixing nip portion formed by the fixing roller82and the pressure belt83to fix the toner image on the recording material S.

In the present embodiment, the image forming apparatus100can perform duplex printing. In the case of single-sided printing, the recording material S on which the toner image is fixed is conveyed to a discharge conveyance path150and discharged to the outside of the image forming apparatus100. In the case of duplex printing, the recording material S on which the toner image is fixed is conveyed to a duplex reverse conveyance path600. The duplex reverse conveyance path600is formed across the first casing101aand the second casing101b. In the duplex reverse conveyance path600, the recording material S is reversed by the switchback operation, and the front surface and the back surface of the recording material S are exchanged. The reversed recording material S is conveyed toward the registration roller12, and is conveyed to the secondary transfer portion T2by the registration roller12in a state where the back surface side that is not printed faces the intermediate transfer belt130side. In the secondary transfer portion T2, the full-color toner images formed on the intermediate transfer belt130are secondarily transferred collectively to the recording material S (back surface side). Thereafter, the toner image is fixed by the fixing unit800, and the recording material S is discharged to the outside of the image forming apparatus100in a state where a surface (image forming surface) on which an image has been formed immediately before faces upward. The above-described switching between the discharge conveyance path150and the duplex reverse conveyance path600is performed by a conveyance switching member160. In the present embodiment, two fixing devices are provided as the fixing unit800, but only one fixing device may be provided. In addition, a cooling unit that cools the recording material S on which the toner image is fixed by the fixing unit800may be provided in the second casing101b.

The finisher device300is connected to the image forming apparatus100so as to be able to transfer the recording material S, and the recording material S discharged from the image forming apparatus100is conveyed to the finisher device300. The recording material S conveyed to the finisher device300is subjected to post-process processing such as punching processing of forming a hole in the recording material S by the finisher device300or stapling processing of bundling and needle-closing a plurality of recording materials S. In the finisher device300, the holed recording material S is separately discharged to an upper sheet discharge tray301, and the bundle of the needle-closed recording materials S is separately discharged to a lower sheet discharge tray302.

Hereinafter, an airflow configuration of outside air in the image forming apparatus100will be described with reference toFIGS.2to9with reference toFIG.1.FIG.2is a left perspective view illustrating the image forming apparatus100in a state where a front door is opened.FIG.3Ais a left perspective view illustrating a state in which the front door of the image forming apparatus100is closed, andFIG.3Bis a right perspective view illustrating a state in which the front door of the image forming apparatus100is closed.

As illustrated inFIG.2, left front door170aand right front door170bas exterior covers are provided on a front surface of first casing101aso as to be openable and closable in a double doors manner as illustrated in the drawing. On the front surface of the first casing101a, an inner cover173is provided inside the left front door170aand right front door170b. The inner cover173is provided to prevent a user from erroneously touching a movable portion, electric wiring, or the like in first casing101awhen the user opens the front doors (170aand170b). However, the inner cover173is detachably attached to the first casing101awith a screw or the like so that a service engineer can perform maintenance work. The inner cover173is formed with an opening portion through which the image forming portions Pa to Pd (illustrated by dotted lines) can be individually inserted into and removed from the first casing101a, and an inner cover unit125is detachably provided on the inner cover173so as to cover the image forming portions Pa to Pd.

As illustrated inFIGS.2and3A, an intake cover171is provided above the left front door170a, and an intake port171ais formed in the intake cover171. On the left surface side of the first casing101a, a left intake unit124having a fan (seeFIGS.4A and4Bdescribed below) that takes in outside air from the intake port171ais provided. In the present embodiment, the outside air taken in from the intake port171ais guided toward the image forming portions Pa to Pd and the charging units2aand2bvia the left intake unit124and the inner cover unit125.

As illustrated inFIG.3B, a right cover172is provided on the right surface of the first casing101a, and an intake port172ais formed in the right cover172. A right intake unit126having a fan (seeFIG.4Bdescribed below) for taking in outside air is provided on the right surface side of the first casing101a, and the outside air is taken in from the intake port172aaccording to the operation of the fan. In the present embodiment, the outside air taken in from the intake port172ais guided to the charging units2cand2dvia the right intake unit126and the inner cover unit125.

In the charging units2ato2d, the surfaces of the photosensitive drums3ato3dare charged by ionizing air by corona discharge to generate ions. In addition, the charging units2ato2dgenerate not only ions but also ozone during the corona discharge. However, since the ozone easily corrodes, for example, a stainless steel grid (not illustrated) or the like included in the charging units2ato2d, ozone needs to be recovered. Therefore, although in the vicinity of the charging units2ato2d, a primary intake duct (not illustrated) that blows outside air to the charging units2ato2dand a primary exhaust duct (not illustrated) that exhausts air to the outside of the image forming apparatus100via the ozone recovery filter are disposed in order to send ozone to an ozone recovery filter (not illustrated) by outside air for recovery.

Left Intake Unit

The left intake unit124will be described with reference toFIGS.4A to7with reference toFIG.1. However, in order to facilitate understanding of the description,FIGS.4A and4Billustrate the airflow configurations of the developing units1ato1dand the airflow configurations of the charging units2ato2dseparately.

As illustrated inFIGS.4A and4B, the left intake unit124includes a left main body duct174, developing intake fans180a,180b,180c, and180d, charging intake fans177aand177b, and side ducts174aand174bdescribed below. The developing intake fans180ato180dare sirocco fans for cooling the developing units1ato1dsupported by the first casing101a. The charging intake fans177aand177bare sirocco fans for sending outside air to the charging units2aand2bsupported by the first casing101a. The left main body duct174is a duct in which a space communicating with the intake port171ais formed.

As illustrated inFIGS.5A and5B, the developing intake fan180das a second fan, the developing intake fan180bas a third fan, the developing intake fan180cas a fourth fan, and the side duct174bare disposed on a right surface portion1742of the left main body duct174as an intake duct. That is, a communication port communicating with the developing intake fans180b,180c, and180dis formed in the right surface portion1742as the second side surface portion, and the outside air taken in from the intake port171aaccording to the operation of the developing intake fans180b,180c, and180dpasses through the inside of the left main body duct174. The developing ducts181b,181c, and181das second ducts are formed inside the side duct174b. The side duct174band the developing intake fans180b,180c, and180dare connected such that the outside air passing through the developing intake fans180b,180c, and180dbranches and passes through the developing ducts181b,181c, and181d. In the present embodiment, the developing ducts181b,181c, and181dare examples of branch portions. The left main body duct174is provided at one side relative to the image forming portions Pa and Pd in the arrangement direction of the plurality of image forming units and configured to take in air outside the image forming apparatus100from the intake port171a.

Meanwhile, as illustrated inFIGS.6A and6B, the developing intake fan180a, the charging intake fans177aand177b, and the side duct174aare disposed on a left surface portion1741facing the right surface portion1742with a distance therebetween in the left main body duct174. That is, a communication port communicating with the developing intake fan180aand the charging intake fans177aand177bas the first fans is formed in the left surface portion1741as the first side surface portion, and the outside air taken in from the intake port171aaccording to the operations of the developing intake fan180aand the charging intake fans177aand177bpasses through the inside of the left main body duct174. The developing duct181aas a first duct and charging ducts178aand178bare formed inside the side duct174a. The side duct174a, the developing intake fan180a, and the charging intake fans177aand177bare connected such that the outside air passing through the developing intake fan180aand the charging intake fans177aand177bbranches and passes through the ducts181a,178a, and178b.

Then, as illustrated inFIG.4A, the outside air taken in from the intake port171ais sent to the developing units1ato1dvia the left main body duct174, the developing intake fans180ato180d, the developing ducts181ato181d, and the inner cover unit125. As illustrated inFIG.4B, the outside air taken in from the intake port171ais sent to the charging units2aand2bvia the left main body duct174, the charging intake fans177aand177b, the charging ducts178aand178b, and the inner cover unit125. In order to remove dust and the like from the outside air taken in from the intake port171a, a filter (not illustrated) is preferably disposed in a flow path from the intake port171ato the left main body duct174.

In the present embodiment, the developing intake fans180ato180dand the charging intake fans177aand177b, which are sirocco fans, are disposed on the left surface portion1741and the right surface portion1742of the left main body duct174with the intake side facing the left main body duct174. As described above, in the left main body duct174, the developing intake fan180aand the charging intake fans177aand177bare disposed on the left surface portion1741, and the developing intake fans180b,180c, and180dare disposed on the right surface portion1742. As described above, by using the ducts from the intake port171ato the developing intake fans180ato180dand the charging intake fans177aand177bas a common duct, it is possible to reduce the area occupied by the ducts as compared with a configuration in which the ducts connecting the fan and the intake port are provided for the number of the plurality of fans, and it is possible to suppress an increase in size of the image forming apparatus itself due to an increase in size of the duct. In addition, since the arrangement of the ducts can be simplified, the degree of freedom in design can be improved without affecting the arrangement of other units.

When the developing intake fans180ato180dand the charging intake fans177aand177bare disposed in the left main body duct174, the inventors have studied arrangement positions where the intake fans are not easily affected by intake air by other intake fans by air flow simulation.FIG.7illustrates the arrangement positions of the developing intake fans180ato180dand the charging intake fans177aand177bin the left intake unit124.

As illustrated inFIG.7, the developing intake fans180ato180dand the charging intake fans177aand177bare disposed at positions not overlapping with each other in an intake direction. In order to achieve this, in the left main body duct174, the communication ports1741ato1741c(first communication ports), the communication port1742a(third communication port), the communication port1742b(fourth communication port), and the communication port1742c(the second communication port) are formed so as not to overlap each other when viewed from the right surface portion1742side (the second side surface portion side) toward the left surface portion1741side (the first side surface portion side) in the passing direction (the rotation axis direction of the fan) of the outside air passing through the developing intake fan180a(the first fan). That is, the communication ports1741ato1741cand the communication ports1742ato1742care formed so as not to overlap each other when viewed from the right surface portion1742side to the left surface portion1741side in the opposing direction where the left surface portion1741side and the right surface portion1742side are facing each other.

As described above, the communication ports1741ato1741cand1742ato1742cin the left main body duct174are disposed at positions not facing each other, and thus, occurrence of drift in the left main body duct174can be suppressed. In the present embodiment, a distance between the left surface portion1741and the right surface portion1742of the left main body duct174is set to 20 mm or more and 50 mm or less. By setting the distance between the left surface portion1741and the right surface portion1742to 20 mm or more in this manner, it is possible to suppress the occurrence of drift in the air flow generated inside the left main body duct174when air is taken in from the communication ports1741ato1741cand the communication ports1742ato1742c.

For example, when the distance between the left surface portion1741and the right surface portion1742is smaller than 20 mm, an air flow generated by being taken in by the developing intake fans180ato180dand the charging intake fans177aand177bhits the left surface portion1741and the right surface portion1742, and thus, a drift occurs. When the drift of air flows occurs, a loss of an air volume when air flowing into the left main body duct174from the intake port171ais discharged from the communication ports1741ato1741cand the communication ports1742ato1742cbecomes large.

Therefore, in the present embodiment, the distance between the left surface portion1741and the right surface portion1742of the left main body duct174is set to 20 mm or more, thereby suppressing the occurrence of drift inside the left main body duct174. As a result, a loss when the air flowing into the left main body duct174from the intake port171ais discharged from the communication ports1741ato1741cand the communication ports1742ato1742ccan be suppressed. Therefore, a sufficient air blowing amount can be secured for the plurality of units.

When the distance between the left surface portion1741and the right surface portion1742is larger than 50 mm, drift is less likely to occur in the left main body duct174. However, the outer shape of the left main body duct174becomes large, and the size of the image forming apparatus itself may be increased in order to accommodate a duct having a large outer shape. Therefore, in the present embodiment, the distance between the left surface portion1741and the right surface portion1742is set to 40 mm in consideration of the influence of the intake air of each intake fan. In this case, no drift occurs in the left main body duct174, and an increase in pressure loss can be suppressed.

Right Intake Unit

Next, the right intake unit126will be described with reference toFIGS.4B,8A, and8B. As illustrated inFIG.4B, the right intake unit126includes a right main body duct176, charging intake fans177cand177d, and a passage duct179to be described below. The charging intake fans177cand177dare fans for blowing outside air to the charging units2cand2dsupported by the first casing101a. The right main body duct176is a duct in which a space communicating with the intake port172a(seeFIG.3B) is formed. In order to remove dust and the like from the outside air taken in from the intake port172a, a filter (not illustrated) is preferably disposed in a flow path from the intake port172ato the right main body duct176.

As illustrated inFIG.8A, the right main body duct176is provided with charging intake fans177cand177dfor blowing outside air to the charging units2cand2d. That is, a communication port communicating with the charging intake fans177cand177dis formed in the right main body duct176, and the outside air taken in from the intake port172aaccording to the operations of the charging intake fans177cand177dpasses through the inside of the right main body duct176. As illustrated inFIG.8B, charging ducts178cand178dare formed in the passage duct179. The passage duct179is connected to the charging intake fans177cand177dsuch that the outside air having passed through the charging intake fans177cand177dpasses through the charging ducts178cand178d.

Then, as illustrated inFIG.4B, the outside air taken in from the intake port172ais sent to the charging units2cand2dvia the right main body duct176, the charging intake fans177cand177d, the charging ducts178cand178d, and the inner cover unit125. Meanwhile, as described above, the outside air taken in from the intake port171a(seeFIG.3B) is sent to the charging units2aand2bvia the left main body duct174, the charging intake fans177aand177b, and the inner cover unit125. As described above, in the present embodiment, the left intake unit124and the right intake unit126are used to blow the outside air to the charging units2ato2d.

Note that the air flow configuration of the developing units1ato1dand the air flow configuration of the charging units2ato2dare not limited to the above-described configurations. For example, the developing intake fans180ato180dmay be disposed in the right surface portion1742of the left intake unit124, and the charging intake fans177aand177bmay be disposed in the left surface portion1741. That is, the number of intake fans disposed on the left surface portion1741and the right surface portion1742of the left intake unit124may not be the same.

Further, for example, one charging intake fan177aand two developing intake fans180aand180bmay be disposed on the left surface portion1741, and three charging intake fans177b,177c, and177dmay be disposed on the right surface portion1742. At this time, the developing intake fans180cand180dare disposed in the right intake unit126. In this case, the charging unit2acorresponds to a first charging unit, and the charging units2b,2c, and2dcorrespond to a second charging unit.

Inner Cover Unit

The inner cover unit125will be described with reference toFIG.9.FIG.9is a schematic view illustrating an inner surface side of the inner cover unit125. In the present embodiment, as illustrated inFIG.9, a flexible tube183aserving as the first relay duct and flexible tubes183b,183c, and183das the second relay ducts are disposed on the inner surface side of the inner cover unit125as relay ducts through which outside air for cooling the developing units1ato1dpasses. Flexible tubes222a,222b,222c, and222dare disposed on the inner surface side of the inner cover unit125as relay ducts through which outside air for blowing air to the charging units2ato2dpasses. The flexible tubes183ato183dand222ato222dare attached to the inner surface of the inner cover unit125using, for example, a wire saddle.

Each of the flexible tubes183ato183dand222ato222dis a bellows-shaped tubular member of which an inside is formed in a hollow tubular shape using, for example, a resin such as PA6 (polyamide) or a metal, and a large number of protrusions are continuously formed at predetermined intervals on the outer peripheral surface, and is bendable. When the flexible tubes183ato183dand222ato222dare curved, the curvature is limited by the protrusion inside the curve (compression side) and it is difficult to bend the flexible tubes. Therefore, even when the flexible tubes183ato183dand222ato222dare curved, the size of the cross-sectional area is maintained as compared with that before the curvature, and the outside air can be guided without changing the air volume per unit time.

With the operations of the developing intake fans180ato180d, the outside air taken in from the intake port171apasses through the left main body duct174, the developing ducts181ato181d, and the flexible tubes183ato183dand flows toward the developing units1ato1d. Further, with the operation of the charging intake fans177aand177b, the outside air taken in from the intake port171apasses through the left main body duct174, the charging ducts178aand178b, and the flexible tubes222aand222band flows toward the charging units2aand2b. Further, with the operation of the charging intake fans177cand177d, the outside air taken in from the intake port172apasses through the right main body duct176, the charging ducts178cand178d, and the flexible tubes222cand222dand flows toward the charging units2cand2d.

In the present embodiment, on the inner surface side of the inner cover unit125, for example, the flexible tubes183ato183dcan be appropriately curved and provided in gaps avoiding the flexible tubes222ato222dand the like that guide outside air to the charging units2ato2d. That is, the use of the flexible tubes183ato183dand222ato222dincreases the degree of freedom of duct arrangement in a limited space. Note that the arrangement of the flexible tubes183ato183dand222ato222dillustrated here is an example, and the arrangement is not limited thereto.

As described above, in the present embodiment, in the left intake unit124, the developing intake fan180aand the charging intake fans177aand177bare disposed on the left surface portion of the left main body duct174. Meanwhile, the developing intake fans180b,180c, and180dare disposed on the right surface portion1742of the left main body duct174. In the left intake unit124, the outside air taken in from the intake port171aaccording to the operations of the developing intake fans180ato180dand the charging intake fans177aand177bis branched into the communication ports1741ato1741cand the communication ports1742ato1742cand blown to the developing units1ato1dand the charging units2aand2b. Accordingly, when the outside air taken in by the intake fan is guided toward the plurality of units via the duct, it is possible to suppress an increase in size of the apparatus and to realize a simple configuration to guide the outside air with a sufficient air blowing amount secured.

Other Embodiments

In the embodiment described above, the sirocco fan is used as the intake fan as an example, but the present invention is not limited to this. An axial fan may be used as the intake fan.FIGS.10A and10Billustrate a case where an axial fan is used instead of the sirocco fan for the developing intake fans180b,180c, and180dand the charging intake fans177aand177bin the left main body duct174.

As illustrated inFIGS.10A and10B, when the axial fans are used for the developing intake fans180ato180dand the charging intake fans177aand177b, side ducts201ato201fare individually provided for each fan. Here, the side duct201eis provided for the developing intake fan180a, the side duct201ais provided for the developing intake fan180b, the side duct201bis provided for the developing intake fan180c, and the side duct201cis provided for the developing intake fan180d. The side duct201dis provided for the charging intake fan177a, and the side duct201fis provided for the charging intake fan177b. As illustrated in the drawing, the side ducts201ato201fare provided so as to cover the exhaust sides of the developing intake fans180ato180dand the charging intake fans177aand177b. Other configurations in the case of using the axial fan are similar to the configurations in the case of using the sirocco fan described above, and thus the description thereof is omitted here.

In the above-described embodiment, the case where outside air is blown to the developing units1ato1dand the charging units2ato2dhas been described as an example, but the present invention is not limited thereto. For example, the above-described embodiment may also be applied to a case where a conveyance member that conveys the recording material S after passing through the first fixing device81and the second fixing device91(seeFIG.1) is cooled by outside air.

Note that, in the above-described embodiment, the electrophotographic image forming apparatus100is described as an example, but the present invention is not limited thereto. For example, the above-described embodiments may be applied to a thermal drying type image forming apparatus such as an inkjet printer or a sublimation type printer.

According to the present invention, when the outside air taken in by the intake fan is guided toward the plurality of units via the duct, it is possible to suppress an increase in size of the device and to realize a simple configuration to guide the outside air with a sufficient air blowing amount secured.

This application claims the benefit of Japanese Patent Application No. 2021-100083, filed Jun. 16, 2021, which is hereby incorporated by reference herein in its entirety.