JP7690328B2 - Image forming device - Google Patents

Description

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

In an image forming apparatus, a toner image is formed on an image carrier such as a photosensitive drum or an intermediate transfer belt, the toner image is transferred from the image carrier to a recording material, and then the toner image is fixed to the recording material by applying heat and pressure by a fixing device. The image forming apparatus is equipped with a developing device that forms a toner image on a photosensitive drum that is charged by a charger. The developing device circulates and transports the toner inside the developing device while stirring it with a transport screw, and heat is generated in response to the stirring operation of the toner. However, if the developing device becomes too hot, the temperature of the toner increases, which causes image defects, so fans, air pumps, etc. have been provided to cool the developing device with outside air. Conventionally, it has been proposed to form a duct that guides outside air toward the developing device using a flexible tube (Patent Document 1). In the device described in Patent Document 1, the flexible tube is arranged so that it is curved with a small curvature. In addition, it has been proposed to use an elastic tube to cool a heat-generating part with air flow (Patent Document 2).

JP 2009-237195 A JP 2002-55589 A

Recently, commercial image forming devices, for example, have come into use that can form toner images on more recording materials in a shorter time. In such devices, a large fan with a large air volume and a tube with a large diameter are installed to increase the volume of air per unit time and pass outside air through. However, since various components are densely packed inside the image forming device and the space for maneuvering the tube is limited, in some places it has been necessary to arrange the tube with a large curvature. However, in the past, when the tube was arranged with a large curvature, the tube could be bent and crushed midway, and there was a risk that the desired volume of outside air would not pass through the tube.

In view of the above problems, the present invention aims to provide an image forming device in which, when a duct is formed using a flexible tube, outside air blown by a fan passes through the tube at a desired volume.

An image forming apparatus according to one embodiment of the present invention is an image forming apparatus that forms an image on a recording material, and comprises a photosensitive member, a charging unit that charges the surface of the photosensitive member by corona discharge, a housing that supports the charging unit, an outer cover that is openably and closably provided on the front of the housing, an inner cover unit that is arranged on the housing facing the inner surface of the outer cover in the closed state, a fan that blows outside air, and a flexible relay duct that is provided on the inner cover unit and guides the outside air blown by the fan toward the charging unit, wherein the relay duct is a bellows-shaped cylindrical member having an uneven outer peripheral surface with convex portions formed along the circumferential direction, and when the relay duct is bent, the bending is limited by the convex portions.

According to the present invention, when the outside air blown by the fan is guided using a flexible relay duct, the outside air blown by the fan can pass through the relay duct at a desired volume.

1 is a schematic diagram showing an image forming system including an image forming apparatus according to an embodiment of the present invention. 1A is a left perspective view showing an image forming apparatus with a front door open; FIG. 1B is a left perspective view showing an image forming apparatus with the front door closed; FIG. 4 is a schematic diagram illustrating an airflow configuration for cooling the developing device according to the first embodiment. FIG. 2A is a right side view showing the left intake unit, and FIG. FIG. 4 is a schematic diagram showing the inner surface side of the inner cover unit. 4A is a front cross-sectional view illustrating the airflow configuration of the developing device, and FIG. 4B is a side cross-sectional view illustrating the airflow configuration of the developing device. FIG. 2A is an enlarged view showing an example of a flexible tube, and FIG. 2B is an enlarged view showing another example of a flexible tube. FIG. 2A is a diagram illustrating an example of the internal shape of a flexible tube, and FIG. 2B is a diagram illustrating another example of the internal shape of a flexible tube. FIG. 2A is a diagram showing an example of the outer shape of a flexible tube, and FIG. 2B is a diagram showing another example of the outer shape of a flexible tube. FIG. 4A is a diagram for explaining the expansion and contraction of a flexible tube, FIG. 4B is a schematic diagram showing a joint, and FIG. 4C is a diagram for explaining the arrangement interval of the joints. 13A and 13B are diagrams illustrating an airflow configuration for collecting scattered toner in a developing device according to a second embodiment, in which FIG. FIG. 11 is a schematic diagram illustrating an air flow in a charging device according to a third embodiment. FIG. 2 is a right perspective view showing the image forming apparatus with the front door closed. FIG. 4 is a schematic diagram illustrating an air flow configuration on the intake side of the charging device. FIG. 4A is a perspective view showing a right-side intake unit, and FIG. FIG. 13 is a schematic view showing the inner surface side of the inner cover unit in the third embodiment. 5A and 5B are diagrams illustrating an airflow configuration on the exhaust side of the charging device, in which FIG.

[First embodiment]
<Image forming system>
A schematic configuration of an image forming system including an image forming apparatus according to this embodiment will be described with reference to Fig. 1. The image forming system 1X shown in Fig. 1 includes an image forming apparatus 100 and a finisher device 300. The image forming apparatus 100 and the finisher device 300 are connected so as to be able to transfer a recording material S. In this embodiment, the finisher device 300 is a post-processing unit that can be added to the image forming apparatus 100 for functional expansion, and can perform a post-processing process (described later) on the recording material S on which a toner image has been fixed by the image forming apparatus 100. The image forming apparatus 100 and the finisher device 300 are connected so as to be able to transmit and receive data between each other via a communication interface capable of serial communication or parallel communication.

<Image forming apparatus>
The image forming apparatus 100 is a tandem-type full-color printer of an electrophotographic system, and has a first housing 101a and a second housing 101b. The first housing 101a is provided with various devices and members, such as an image forming unit 700 that realizes the process from conveying a recording material S to transferring a toner image.

On the other hand, the second housing 101b is provided with various devices and components such as a fixing unit 800 that conveys the recording material S and fixes the toner image. The second housing 101b is also provided with an operation unit 200 having a display unit capable of displaying various information on the front side and keys that allow the user to input various information according to the user's operation. An electrical unit (not shown) having a power supply board may be provided on the rear side of the first housing 101a and the second housing 101b. In this specification, the side on which the user stands when operating the operation unit 200 to operate the image forming apparatus 100 is referred to as the "front" and the opposite side is referred to as the "rear". The left side as viewed from the front is referred to as the "left side" and the right side as viewed from the front is referred to as the "right side".

Image forming apparatus 100 includes image forming units Pa, Pb, Pc, and Pd that form images of yellow, magenta, cyan, and black, respectively. Image forming apparatus 100 forms a toner image on recording material S in response to an image signal received from an original reading device 190 that reads an image signal from an original or an external device (not shown) such as a personal computer.

In this embodiment, the image forming units Pa to Pd, the primary transfer rollers 24a to 24d, the intermediate transfer belt 130, the rollers 13 to 15, and the secondary transfer outer roller 11 constitute an image forming unit 700 that forms a toner image on the recording material S. Examples of the recording material S include plain paper, thick paper, rough paper, textured paper, coated paper, and other paper, as well as plastic film and cloth.

As shown in FIG. 1, the image forming units Pa to Pd are arranged in a line along the movement direction of the intermediate transfer belt 130. The intermediate transfer belt 130 is stretched around a number of rollers (13, 14, 15) and moved in the direction of the arrow R2. The intermediate transfer belt 130 carries and transports the toner image that is primarily transferred as described below. The secondary transfer outer roller 11 is arranged at a position opposite the secondary transfer inner roller 14 that stretches the intermediate transfer belt 130 and sandwiches the intermediate transfer belt 130 therebetween, forming a secondary transfer unit T2 that transfers the toner image on the intermediate transfer belt 130 to the recording material S. A fixing unit 800 is arranged downstream of the secondary transfer unit T2 in the recording material transport direction.

At the lower side of the image forming apparatus 100, multiple cassettes 10 (two in this example) containing recording materials S are arranged. These cassettes 10 contain recording materials S of different sizes and thicknesses, and the recording material S is selectively transported from one of the cassettes 10. The recording material S is transported from the cassette 10 to the registration roller 12 through a transport path by the transport roller 16. The registration roller 12 then rotates in synchronization with the toner image formed on the intermediate transfer belt 130, transporting the recording material S toward the secondary transfer section T2. Note that the recording material S is not limited to that contained in the cassette 10, and recording material S placed on a manual feed section (not shown) may also be transported.

The image forming units Pa, Pb, Pc, and Pd are essentially identical in configuration, except that the toner image development colors are different. Therefore, here we will explain the yellow image forming unit Pa as a representative, and will omit explanations of the other image forming units Pb, Pc, and Pd.

In the image forming section Pa, a cylindrical photosensitive drum 3a is disposed as a photosensitive member. The photosensitive drum 3a is rotated by a motor (not shown). Around the photosensitive drum 3a, a charging device 2a as a charging unit, an exposure device La, a developing device 1a as a developing unit, a primary transfer roller 24a, and a drum cleaning device 4a are disposed.

The process of forming, for example, a full-color image by the image forming apparatus 100 will be described. First, when the image forming operation is started, the surface of the rotating photosensitive drum 3a is uniformly charged by the charging device 2a. The charging device 2a is, for example, a corona charger that irradiates charged particles associated with corona discharge to charge the surface of the photosensitive drum 3a to a uniform potential. Next, the photosensitive drum 3a is scanned and exposed by a laser beam corresponding to an image signal emitted from the exposure device La. As a result, an electrostatic latent image corresponding to the image signal is formed on the surface of the photosensitive drum 3a. The electrostatic latent image formed on the photosensitive drum 3a is developed into a visible toner image by a developer containing toner and carrier contained in the developing device 1a. Note that in the developing devices 1a to 1d, the developer is circulated and transported while being stirred by a transport screw (not shown).

The toner image formed on the photosensitive drum 3a is primarily transferred to the intermediate transfer belt 130 at a primary transfer section T1 formed between the photosensitive drum 3a and a primary transfer roller 24a arranged with the intermediate transfer belt 130 sandwiched therebetween. At this time, a primary transfer voltage is applied to the primary transfer roller 24a. Any toner remaining on the surface of the photosensitive drum 3a after the primary transfer is removed by a drum cleaning device 4a.

This operation is performed in sequence at each of the image forming units Pa to Pd for yellow, magenta, cyan, and black, and the four color toner images are superimposed on the intermediate transfer belt 130. After that, the recording material S stored in the cassette 10 is transported to the secondary transfer unit T2 in accordance with the timing of the formation of the toner images. Then, by applying a secondary transfer voltage to the outer secondary transfer roller 11, the full-color toner image formed on the intermediate transfer belt 130 is secondary-transferred all at once to the recording material S. Note that any toner remaining on the intermediate transfer belt 130 after the secondary transfer is removed by a belt cleaning device (not shown).

The recording material S onto which the toner image has been transferred is transported to the fixing unit 800. The fixing unit 800 applies heat and pressure to the recording material S onto which the toner image has been transferred, thereby fixing the toner image to the recording material S. In the present embodiment, the first fixing device 81 applies heat and pressure to the recording material S, and then the second fixing device 91 can selectively apply heat and pressure to the recording material S. The fixing unit 800 is switched by a fixing switching flapper 95 between transporting the recording material S towards the second fixing device 91 after passing through the first fixing device 81, or transporting the recording material S by avoiding the second fixing device 91 after passing through the first fixing device 81.

The second fixing device 91 is disposed downstream of the first fixing device 81 in the conveying direction of the recording material S. The second fixing device 91 is selectively used for the purpose of further imparting gloss to the toner image on the recording material S fixed by the first fixing device 81. For example, when the recording material S is coated paper such as glossy paper or synthetic paper, the recording material S that has passed through the first fixing device 81 is conveyed through the fixing route 30a so that fixing is performed by both the first fixing device 81 and the second fixing device 91. On the other hand, when the recording material S is uncoated paper such as plain paper, the recording material S that has passed through the first fixing device 81 is conveyed through the fixing bypass route 30b that avoids the second fixing device 91 so that fixing is performed by the first fixing device 81 but not by the second fixing device 91.

The first fixing device 81 and the second fixing device 91 may have the same configuration, so the first fixing device 81 will be described here as an example. The first fixing device 81 has a fixing roller 82 (or fixing belt) that can rotate in contact with the surface of the recording material S on which the toner image is fixed, and a pressure belt 83 (or pressure roller) that presses against the fixing roller 82 to form a fixing nip portion. At least one of the fixing roller 82 and the pressure belt 83 is heated by a heater (not shown). The first fixing device 81 applies heat and pressure to the recording material S on which the toner image is formed when nipping and conveying the recording material S in the fixing nip portion formed by the fixing roller 82 and the pressure belt 83, thereby fixing the toner image to the recording material S.

In the present embodiment, the image forming apparatus 100 is capable of double-sided printing. In the case of single-sided printing, the recording material S on which the toner image is fixed is conveyed to the discharge conveying path 150 and discharged to the outside of the image forming apparatus 100. In the case of double-sided printing, the recording material S on which the toner image is fixed is conveyed to the double-sided inversion conveying path 600. The double-sided inversion conveying path 600 is formed across the first housing 101a and the second housing 101b. In the double-sided inversion conveying path 600, the recording material S is inverted by a switchback operation, and the front and back sides of the recording material S are swapped. The inverted recording material S is conveyed toward the registration roller 12, and conveyed to the secondary transfer section T2 with the unprinted back side facing the intermediate transfer belt 130 side by the registration roller 12. In the secondary transfer section T2, the full-color toner image formed on the intermediate transfer belt 130 is secondarily transferred to the recording material S (back side) all at once. Thereafter, the toner image is fixed to the recording material S by the fixing unit 800, and the recording material S is discharged to the outside of the image forming apparatus 100 with the surface on which the image was just formed (image forming surface) facing upward. Note that switching between the discharge conveying path 150 and the double-sided reversing conveying path 600 is performed by a conveying switching flapper 160. Note that in this embodiment, the fixing unit 800 is configured to include two fixing devices, but it may also be configured to include only one fixing device. Also, the second housing 101b may be configured to include a cooling device that cools the recording material S on which the toner image has been fixed by the fixing unit 800.

A finisher device 300 is connected to the image forming device 100 so that recording material S can be handed over, and recording material S discharged from the image forming device 100 is transported to the finisher device 300. The recording material S transported to the finisher device 300 is subjected to post-processing such as punching processing to make holes in the recording material S, or stapling processing to bundle multiple sheets of recording material S and staple them together. In the finisher device 300, the punched recording material S is discharged to an upper discharge tray 301, and the stapled bundle of recording materials S is discharged to a lower discharge tray 302.

Next, the airflow configuration for the outside air in the image forming apparatus 100 will be described. First, as a first embodiment, the airflow configuration for cooling the developing devices 1a to 1d will be described. FIG. 2(a) shows the image forming apparatus 100 with the front door open, and FIG. 2(b) shows the image forming apparatus 100 with the front door closed.

As shown in FIG. 2A, the front of the first housing 101a is provided with a left front door 170a and a right front door 170b as exterior covers that can be opened and closed like double doors as shown in the figure. An intake cover 171 is provided above the left front door 170a, and an intake port 171a is formed in the intake cover 171. In addition, an inner cover 173 is provided on the front of the first housing 101a, inside the left front door 170a and the right front door 170b. The inner cover 173 is provided to prevent the user from accidentally touching the moving parts and electrical wiring inside the first housing 101a when the user opens the front doors (170a, 170b). However, the inner cover 173 is provided detachably to the first housing 101a by screws or the like so that a serviceman can perform maintenance work. This inner cover 173 has openings that allow the image forming units Pa to Pd (shown by dotted lines) to be individually inserted and removed from the first housing 101a, and the inner cover unit 125 is detachably attached to the inner cover 173 so as to cover and conceal the image forming units Pa to Pd.

As shown in FIG. 2B, a left-side intake unit 124 having a fan (see FIG. 3 described later) that draws in outside air from the intake port 171a is provided on the left side of the first housing 101a. In this embodiment, the outside air drawn in from the intake port 171a is guided toward the image forming units Pa to Pd via the left-side intake unit 124 and the inner cover unit 125.

<Left side intake unit>
The left-side intake unit 124 will be described with reference to Figures 3 and 4(b). As shown in Figure 3, the left-side intake unit 124 has a left-side main body duct 174, a plurality of development intake fans 180a, 180b, 180c, and 180d for cooling the development devices 1a to 1d supported by the first housing 101a, and side ducts 174a and 174b, which will be described later. The left-side main body duct 174 is a duct in which a space communicating with the above-mentioned intake port 171a is formed. In order to remove dust and the like from the outside air taken in through the intake port 171a, it is preferable to place a filter (not shown) in the middle of the flow path from the intake port 171a to the left-side main body duct 174.

As shown in FIG. 4A, the right side of the left main body duct 174 is provided with the development intake fans 180b, 180c, and 180d and the side duct 174b to cool the development devices 1b, 1c, and 1d. A communication portion that communicates with the development intake fans 180b, 180c, and 180d is formed on the right side of the left main body duct 174, and the outside air sucked in from the intake port 171a in response to the operation of the development intake fans 180b, 180c, and 180d passes through the inside of the left main body duct 174. The side duct 174b has multiple development ducts (181b, 181c, and 181d) formed inside. The side duct 174b is connected to the development intake fans 180b, 180c, and 180d so that the outside air that has passed through the development intake fans 180b, 180c, and 180d passes through each development duct (181b, 181c, 181d).

On the other hand, as shown in FIG. 4B, the left side of the left main body duct 174 is provided with a development intake fan 180a and a side duct 174a to cool the development device 1a. In addition, in this embodiment, as described in detail later, charging intake fans 177a and 177b are provided to send outside air to the charging devices 2a and 2b (see FIG. 1). A communication portion that communicates with the development intake fan 180a and the charging intake fans 177a and 177b is formed on the left side of the left main body duct 174, and the outside air sucked in from the intake port 171a in response to the operation of the development intake fan 180a and the charging intake fans 177a and 177b passes through the inside of the left main body duct 174. The side duct 174a is provided with a development duct 181a and charging ducts 178a and 178b inside. The side duct 174a is connected to the development intake fan 180a and the charging intake fans 177a and 177b so that the outside air that has passed through the development intake fan 180a and the charging intake fans 177a and 177b passes through each duct (181a, 178a, 178b).

Then, as shown in FIG. 3, the outside air drawn in from the intake port 171a is sent to the developing devices 1a to 1d via the left main body duct 174, the developing intake fans 180a to 180d, the developing ducts 181a to 181d, and the inner cover unit 125.

<Inner cover unit>
The inner cover unit 125 will be described with reference to Fig. 5. Fig. 5 is a schematic diagram showing the inner surface side of the inner cover unit 125. In this embodiment, as shown in Fig. 5, flexible tubes 183a, 183b, 183c, and 183d are disposed on the inner surface side of the inner cover unit 125 as relay ducts through which outside air passes to cool the developing devices 1a to 1d. The flexible tubes 183a to 183d are attached to the inner surface of the inner cover unit 125 by using, for example, a wire saddle.

In addition, on the inner surface of the inner cover unit 125, inlet joints 182a, 182b, 182c, 182d and outlet joints 184a, 184b, 184c, 184d are provided to allow outside air to pass through. The inlet joints 182a to 182d as first joint members are fixed at positions where they are connected to the outlets of the above-mentioned development ducts 181a to 181d. The outlet joints 184a to 184d as second joint members are fixed at positions facing the development devices 1a to 1d where they can efficiently cool the development devices 1a to 1d. One end of the flexible tubes 183a to 183d is connected to the inlet joints 182a to 182d, and the other end is connected to the outlet joints 184a to 184d. Note that the arrangement of the flexible tubes 183a to 183d shown here is an example and is not limited to this.

The outside air drawn in from the intake port 171a by the operation of the development intake fans 180a-180d passes through the left main body duct 174 and the development ducts 181a-181d as described above, and reaches the inlet joints 182a-182d. The outside air then passes through the flexible tubes 183a-183d and flows from the outlet joints 184a-184d toward the development devices 1a-1d. In this embodiment, the flexible tubes 183a-183d can be appropriately curved and stretched around the gaps on the inner side of the inner cover unit 125, avoiding the flexible tubes 222a-222d that guide the outside air to the charging devices 2a-2d. In other words, the use of the flexible tubes 183a-183d increases the degree of freedom in duct arrangement within a limited space.

Here, the airflow configuration after the outlet joints 184a to 184d will be explained using Figures 6(a) and 6(b). However, since the airflow configuration of the developing devices 1a to 1d is the same, the airflow configuration of the yellow developing device 1a is shown here as an example.

Figure 6(a) is a front cross-sectional view for explaining the airflow configuration of developing device 1a, and Figure 6(b) is a side cross-sectional view for explaining the airflow configuration of developing device 1a. As shown in Figure 6(a), developing device 1a has upper sleeve 210a, lower sleeve 211a, and conveying screws 212a and 213a. Upper sleeve 210a and lower sleeve 211a carry developer and rotate to supply the developer to photosensitive drum 3a. Conveying screws 212a and 213a circulate and convey developer in opposite directions within developing device 1a while stirring it.

A developer cooling duct 186a is provided above the developing device 1a. A heat sink 187 that is elongated in the front-to-rear direction (the direction of the rotational axis of the conveying screws 212a, 213a) is provided below the developer cooling duct 186a and above the conveying screw 212a. The developer cooling duct 186a is positioned so that it can blow outside air to the developing device 1a on the side closer to the conveying screws 212a, 213a than the upper sleeve 210a and lower sleeve 211a in a direction that intersects with the direction of the rotational axis of the conveying screws 212a, 213a.

As shown in FIG. 6B, the developer cooling duct 186a is formed along the developing device 1a in the direction of the rotation axis of the conveying screws 212a and 213a. The air that passes through the outlet joint 184a is exhausted to the rear side of the device through the developer cooling duct 186a. At this time, the heat sink 187 is cooled by the air flow passing through the developer cooling duct 186a. In this way, the heat sink 187 located above the conveying screw 212a is cooled, thereby indirectly cooling the developing device 1a, which generates heat as the conveying screws 212a and 213a rotate.

Next, the flexible tubes 183a to 183d, inlet joints 182a to 182d, and outlet joints 184a to 184d described above will be explained using Figures 7(a) to 10(c). Note that the inlet joints 182a to 182d and the outlet joints 184a to 184d may be the same. In the following, the flexible tube 183a and the inlet joint 182a will be explained as representative examples.

<Flexible tube>
The flexible tube 183a is formed in a hollow cylindrical shape, and is a bellows-shaped cylindrical member with a number of convex portions 1831 continuously formed at a predetermined interval on the outer circumferential surface as shown in Fig. 7(a). Alternatively, as shown in Fig. 7(b), the flexible tube 183a may be a bellows-shaped cylindrical member with a spiral convex portion 1832 formed on the outer circumferential surface. In this way, the flexible tube 183a is a bellows-shaped cylindrical member having a continuous uneven outer circumferential surface with convex portions 1831 (1832) formed along the circumferential direction.

The inner peripheral surface of the flexible tube 183a may be an uneven surface with recesses 1833 formed to match the protrusions 1831 on the outer peripheral surface, as shown in FIG. 8(a). In other words, the protrusions 1831 are hollow. Alternatively, the inner peripheral surface of the flexible tube 183a may be a flat surface without the recesses 1833 described above, as shown in FIG. 8(b). In this case, the protrusions 1831 are not hollow.

As shown in FIG. 9(a), the flexible tube 183a has a circular cross section. Alternatively, as shown in FIG. 9(b), the flexible tube 183a may have a rectangular cross section.

The flexible tube 183a is a cylindrical member formed to be freely bendable using resin such as PA6 (polyamide) or metal. For example, the flexible tube 183a is formed to have an inner diameter of 16 mm, a cross-sectional area of approximately 200 ^mm2 , and a wall thickness of 0.1 mm when the desired volume of outside air passing through the flexible tube 183a is 0.1 ^m3 /min. The convex portion 1831 is formed so that the bending radius of the flexible tube 183a when bent is approximately 35 mm.

As shown in FIG. 10(a), when the flexible tube 183a is bent, tensile stress is applied to the convex portion 1831 on the outer peripheral surface of the curved outer side, which is the tension side, so the convex portion 1831 deforms so that the corners of the tip and base become obtuse angles. On the other hand, compressive stress is applied to the convex portion 1831 on the outer peripheral surface of the curved inner side, which is the compression side, so the convex portion 1831 deforms so that the corners of the tip and base become acute angles.

The bending limit of the flexible tube 183a in the case of plastic deformation on the tension side is determined by the elongation rate of the material used for the flexible tube 183a. The bending limit of the flexible tube 183a in the case of elastic deformation on the compression side is determined by the Young's modulus, tensile stress, and compressive stress of the material used for the flexible tube 183a. Furthermore, on the compression side, the bending limit is reached when adjacent convex portions 1831 collide with each other and the flexible tube 183a cannot be bent any further. In this embodiment, the flexible tube 183a is not broken at the bending limit and maintains the inner diameter (e.g., 16 mm) before bending. In other words, when the flexible tube 183a is bent, the bending is limited by the convex portions 1831 on the inside of the bend (compression side).

Specifically, the height of the convex portion 1831 of the flexible tube 183a is, for example, "2.5 mm or more and 7 mm or less," and the interval between adjacent convex portions 1831 is, for example, "2 mm or more and 5 mm or less." When such a flexible tube 183a is bent, the bending limit of the flexible tube 183a is a bending radius of approximately "35 mm." Therefore, by changing the height of the convex portion 1831 of the flexible tube 183a or the interval between adjacent convex portions 1831 in advance, the bending limit of the flexible tube 183a can be changed.

<Joint>
10B shows an example of the inlet joint 182a. The inlet joint 182a has ducts connected to the inlet and outlet of the outside air. To give a specific example, in the case of the inlet joint 182a, the developing duct 181a is connected to the inlet, and the flexible tube 183a is connected to the outlet. In the case of the outlet joint 184a, the flexible tube 183a is connected to the inlet, and the developing/cooling duct 186a is connected to the outlet.

As shown in FIG. 10(b), the inlet joint 182a is formed so that the inlet and outlet directions differ by, for example, 90 degrees in order to change the direction of the flowing outside air. In this embodiment, the inlet joints 182a to 182d and the outlet joints 184a to 184d are formed so that they can connect to flexible tubes 183a to 183d that are bent to a curvature smaller than the bending limit.

As shown in FIG. 10(c), the flexible tube 183a is formed to have a length such that its free length before connection is longer than the distance between the inlet joint 182a and the outlet joint 184a to be connected. In this way, when the flexible tube 183a is connected to the inlet joint 182a and the outlet joint 184a, compressive stress is applied to both ends of the flexible tube 183a. Therefore, the flexible tube 183a is connected in a state of close contact with the inlet joint 182a and the outlet joint 184a.

As described above, in this embodiment, bellows-shaped flexible tubes 183a-183d with multiple protrusions 1831 formed on the outer periphery are used as relay ducts to guide outside air blown by a fan. When these flexible tubes 183a-183d are bent, the bending is restricted by the protrusions 1831 on the inside of the bend (compression side), making them difficult to bend. Therefore, even when the flexible tubes 183a-183d are bent, the cross-sectional area is maintained compared to before bending, and outside air can be guided without changing the amount of air per unit time. Therefore, by using the above-mentioned flexible tubes 183a-183d, it is easy to improve the design freedom of the developing devices 1a-1d and relay ducts.

In addition, in the past, it was necessary to mold a duct with a complex shape to match the airflow path, but this is not necessary in this embodiment. Therefore, the number of molds required to mold the flexible tubes can be reduced, and versatile flexible tubes (183a to 183d) can be produced inexpensively, thereby reducing costs.

[Second embodiment]
Next, as a second embodiment, an airflow configuration for collecting scattered toner generated in the development of a toner image in the developing devices 1a to 1d will be described. In the image forming apparatus 100, toner is supplied from the developing devices 1a to 1d to the photosensitive drums 3a to 3d to develop a toner image, but at that time, toner that is not supplied to the photosensitive drums 3a to 3d and scatters (referred to as scattered toner) exists.

As shown in FIG. 6(a) above, for example, in developing device 1a, toner is supplied to photosensitive drum 3a by upper sleeve 210a and lower sleeve 211a, but the remaining toner that is not supplied to photosensitive drum 3a is collected in mixing chamber 214. However, some of the toner that is not supplied to photosensitive drum 3a may scatter outside developing device 1a without being collected in mixing chamber 214. This scattered toner may soil the inside of image forming device 100 and cause image defects. Therefore, a toner recovery unit is provided so that the scattered toner can be sent to the toner recovery unit by outside air and collected. The following will explain developing device 1a as a representative example.

As shown in Figures 11(a) and 11(b), the toner recovery unit 400 has an exhaust duct 217a, a development exhaust fan 214a, and a toner recovery filter 218a, and is disposed on the rear side (right side in Figure 11(a)) of the first housing 101a. The development exhaust fan 214a and the toner recovery filter 218a are provided in the exhaust duct 217a. A scattering recovery duct 215a is disposed below the lower sleeve 211a of the developing device 1a. The scattering recovery duct 215a is formed along the rotation axis direction of the lower sleeve 211a. The scattering recovery duct 215a is formed with multiple recovery ports, and toner scattered below the lower sleeve 211a enters through these recovery ports.

The scattering recovery duct 215a and the exhaust duct 217a of the toner recovery unit 400 are connected by a flexible tube 216a similar to the flexible tube 183a described above as a relay duct. The outside air containing the scattering toner is exhausted from the scattering recovery duct 215a to the outside of the image forming device 100 through the flexible tube 216a and the exhaust duct 217a by the air flow generated by the development exhaust fan 214a. The toner recovery filter 218a is disposed midway in the flow path between the flexible tube 216a and the development exhaust fan 214a. Therefore, toner is removed from the outside air as it passes through the toner recovery filter 218a, and the air from which the toner has been removed is exhausted to the outside of the image forming device 100.

The above airflow configuration is the same for developing devices 1a to 1d, and a flexible tube similar to flexible tube 216a is provided as an intermediate duct. This provides the same effect as the first embodiment described above, such as improved design freedom for developing devices 1a to 1d and the duct. In addition, the flexible tube can be curved and arranged without gaps in the ventilation path while maintaining the cross-sectional area, suppressing pressure loss in the duct and allowing outside air to be exhausted to the outside of image forming device 100 without letting toner escape.

[Third embodiment]
Next, as a third embodiment, the airflow configuration in the charging devices 2a to 2d supported by the first housing 101a will be described. In FIG. 12, the charging device 2a is taken as a representative example. As shown in FIG. 12, the charging device 2a ionizes the air around the charging wire 203a by corona discharge to generate ions, thereby charging the surface of the photosensitive drum 3a. Since the air is ionized to generate ions, it is necessary to blow outside air to the charging device 2a. In order to blow outside air to the charging device 2a, a primary intake duct 202a is disposed near the charging device 2a. In addition, the charging device 2a generates not only ions but also ozone during corona discharge. However, ozone needs to be collected because it easily corrodes, for example, a stainless steel grid (not shown) that the charging device 2a has. Therefore, in order to transport the ozone to an ozone collection filter 219a (see FIG. 17A) by outside air and collect it, a primary exhaust duct 204a is provided near the charging device 2a.

As shown in FIG. 13, a right-side intake unit 126 having a fan (see FIG. 14 described later) for drawing in outside air is provided on the right side of the first housing 101a, and draws in outside air from an intake port 172a in response to the operation of the fan. The intake port 172a is formed in a right cover 172 provided on the right side of the first housing 101a. The outside air drawn in from the intake port 172a is guided to the charging devices 2c and 2d by the charging intake fans 177c and 177d described later via the right-side intake unit 126 and the inner cover unit 125.

<Right side intake unit>
The right-side intake unit 126 will be described with reference to Figures 14 to 15(b). As shown in Figure 14, the right-side intake unit 126 has a right-side main body duct 176, charging intake fans 177c and 177d for blowing outside air to the charging devices 2c and 2d, and a passage duct 179, which will be described later. The right-side main body duct 176 is a duct in which a space communicating with the above-mentioned intake port 172a is formed. In order to remove dust and the like from the outside air taken in through the intake port 172a, it is preferable to place a filter (not shown) in the middle of the flow path from the intake port 172a to the right-side main body duct 176.

As shown in FIG. 15(a), the left side of the right-side main body duct 176 is provided with charging intake fans 177c and 177d for blowing outside air to the charging devices 2c and 2d. That is, a communication portion that communicates with the charging intake fans 177c and 177d is formed on the left side of the right-side main body duct 176, and the outside air sucked in from the intake port 172a in response to the operation of the charging intake fans 177c and 177d passes through the inside of the right-side main body duct 176. Then, as shown in FIG. 15(b), the passing duct 179 is formed with charging ducts 178c and 178d inside. The passing duct 179 is connected to the charging intake fans 177c and 177d so that the outside air that has passed through the charging intake fans 177c and 177d passes through the charging ducts 178c and 178d.

As shown in FIG. 14, the outside air sucked in from the above-mentioned intake port 172a is sent to the charging devices 2c and 2d via the right-side main body duct 176, the charging intake fans 177c and 177d, the charging ducts 178c and 178d, and the inner cover unit 125. On the other hand, for the charging devices 2a and 2b, the outside air sucked in from the above-mentioned intake port 171a is sent via the left-side main body duct 174, the charging intake fans 177a and 177b, and the inner cover unit 125. In this way, in this embodiment, the left-side intake unit 124 and the right-side intake unit 126 are used to blow outside air to the charging devices 2a to 2d.

<Inner cover unit>
The inner cover unit 125 will be described with reference to Fig. 16. Fig. 16 is a schematic diagram showing the inner surface side of the inner cover unit 125. However, in Fig. 16, flexible tubes 183a to 183d through which outside air passes to cool the above-mentioned developing devices 1a to 1d and the like are omitted from the illustration.

In this embodiment, as shown in FIG. 16, flexible tubes 222a, 222b, 222c, and 222d are arranged on the inner surface of the inner cover unit 125 as relay ducts for passing outside air to be blown to the charging devices 2a to 2d. The flexible tubes 222a to 222d are attached to the inner surface of the inner cover unit 125 using, for example, a wire saddle. The flexible tubes 222a to 222d are similar to the flexible tube 183a described above.

In addition, inlet joints 221a, 221b, 221c, 221d and outlet joints 224a, 224b, 224c, 224d are fixed to the inner surface of the inner cover unit 125. The inlet joints 221a to 221d are fixed at positions where they are connected to the outlets of the charging ducts 178a to 178d described above. The outlet joints 224a to 224d are fixed at positions facing the charging devices 2a to 2d that can efficiently blow outside air to the charging devices 2a to 2d. One end of the flexible tubes 222a to 222d is connected to the inlet joints 221a to 221d, and the other end is connected to the outlet joints 224a to 224d. Note that the arrangement of the flexible tubes 222a to 222d shown here is an example and is not limited to this.

The outside air drawn in from the intake port 172a by the operation of the charging intake fans 177c and 177d passes through the right body duct 176 and the charging ducts 178c and 178d as described above, and reaches the inlet joints 221c and 221d. Also, the outside air drawn in from the intake port 171a by the operation of the charging intake fans 177a and 177b passes through the left body duct 174 and the charging ducts 178a and 178b as described above, and reaches the inlet joints 221a and 221b. The outside air then passes through the flexible tubes 222a to 222d and flows from the outlet joints 224a to 224d to the charging devices 2a to 2d for each of the primary intake ducts. In this way, outside air is blown to the charging devices 2a-2d through the flexible tubes 222a-222d, allowing the charging devices 2a-2d to form an air flow that collects the ozone generated by the corona discharge used to charge the photosensitive drums 3a-3d.

In this way, the flexible tubes 183a to 183d that guide outside air to the developing devices 1a to 1d, as well as the flexible tubes 222a to 222d that guide outside air to the charging devices 2a to 2d, can be curved and stretched around, allowing for a high degree of freedom in duct arrangement.

Next, the airflow configuration on the exhaust side of charging devices 2a to 2d will be described with reference to Figures 17(a) and 17(b). Figures 17(a) and 17(b) show the airflow configuration on the exhaust side of charging device 2a as a representative example.

As shown in Figures 17(a) and 17(b), an ozone recovery unit 500 is disposed on the rear side (right side in Figure 17(a)) of the first housing 101a in order to remove ozone generated by the above-mentioned corona discharge. The ozone recovery unit 500 has an exhaust duct 217a that can also be used for toner recovery, a charging exhaust fan 220a, and an ozone recovery filter 219a. The charging exhaust fan 220a and the ozone recovery filter 219a are provided in the exhaust duct 217a.

The primary exhaust duct 204a and the exhaust duct 217a of the ozone recovery unit 500 are connected by a flexible tube 223a similar to the flexible tube 183a described above as a relay duct. The outside air containing the ozone is exhausted from the primary exhaust duct 204a through the flexible tube 223a and the exhaust duct 217a to the outside of the image forming apparatus 100 by the air flow generated by the charging exhaust fan 220a. The ozone recovery filter 219a is disposed in the middle of the flow path between the flexible tube 223a and the charging exhaust fan 220a. Therefore, ozone is removed from the outside air when it passes through the ozone recovery filter 219a, and the air from which the ozone has been removed is exhausted to the outside of the image forming apparatus 100.

The airflow configuration on the exhaust side described above is the same for charging devices 2a to 2d, and a flexible tube is provided as a relay duct. In this way, since a flexible tube is provided as a relay duct, there is a high degree of freedom in duct arrangement even in the airflow configuration for ozone recovery. In addition, it is easy to arrange the flexible tube in a curved manner so as to prevent ozone from escaping while suppressing pressure loss in the duct.

<Other embodiments>
In the above-described embodiment, the case where outside air is blown to the developing devices 1a to 1d and the charging devices 2a to 2d has been described as an example, but the present invention is not limited to this. For example, the above-described embodiment may also be applied to a case where the conveying member that conveys the recording material S after passing through the first fixing device 81 and the second fixing device 91 (see FIG. 1) is cooled by outside air.

In the above-described embodiment, the image forming apparatus 100 is an electrophotographic type, but the present invention is not limited to this. For example, the above-described embodiments may also be applied to image forming apparatuses that use a thermal drying method, such as inkjet printers and dye-sublimation printers.

1a...developing unit (developing device), 2a...charging unit (charging device), 3a...photosensitive member (photosensitive drum), 100...image forming device, 101a...housing (first housing), 125...inner cover unit, 170a, 170b...exterior cover (left front door, right front door), 177a...fan (charging intake fan), 180a...fan (developing intake fan), 182a (221a)...first joint member (inlet joint), 183a (216a, 222a, 223a)...relay duct (flexible tube), 184a (224a)...second joint member (outlet joint), 214a...fan (developing exhaust fan), 218a...toner recovery filter, 219a...ozone recovery filter, 220a...fan (charging exhaust fan), 400...toner recovery unit, 500...ozone recovery unit, S...recording material

Claims (7)

An image forming apparatus for forming an image on a recording material,
A photoconductor;
a charging unit for charging the surface of the photoconductor by corona discharge;
A housing supporting the charging unit;
an exterior cover provided on a front surface of the housing in an openable and closable manner;
an inner cover unit disposed on the housing so as to face an inner surface of the outer cover in a closed state;
A fan to blow outside air,
a flexible relay duct that is provided in the inner cover unit and guides the outside air blown by the fan toward the charging unit,
the relay duct is a bellows-shaped cylindrical member having an uneven outer peripheral surface with convex portions formed along a circumferential direction, and when the relay duct is bent, the bending is restricted by the convex portions.
1. An image forming apparatus comprising: A first joint member provided on the inner cover unit so as to allow outside air to pass therethrough;
A second joint member provided on the inner cover unit to allow outside air to pass therethrough,
The relay duct has one end connectable to the first joint member and the other end connectable to the second joint member, and a free length before being connected to the first joint member and the second joint member is longer than an arrangement distance between the first joint member and the second joint member.
2. The image forming apparatus according to claim 1 , an ozone recovery unit connected to the charging unit so as to allow outside air to pass therethrough and having an ozone recovery filter for recovering ozone generated in association with corona discharge when the photoconductor is charged by the charging unit;
The relay duct is connected to the ozone recovery unit and guides the outside air blown by the fan to the ozone recovery filter.
2. The image forming apparatus according to claim 1 , The relay duct has an uneven inner circumferential surface with the protrusion formed in a hollow space.
4. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. The convex portion is formed in a spiral shape.
5. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. The relay duct is made of metal and is flexible.
6. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction. The relay duct is made of resin and is flexible.
7. The image forming apparatus according to claim 1, wherein the first and second electrodes are arranged in a first direction.

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