JP2018081257A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus that has a plurality of image forming parts horizontally arranged vertically above an endless belt-like body, and to reduce the size of the image forming apparatus and exhaust heat of a power supply unit.SOLUTION: An image forming apparatus has a plurality of image forming parts arranged in a horizontal direction vertically above an endless belt-like body that is stretched by a plurality of rotating bodies and conveyed in circulation. The image forming apparatus comprises: a first side plate that supports one ends of the plurality of rotating bodies; a second side plate that faces the first side plate with the endless belt-like body therebetween and supports the other ends of the plurality of rotating bodies; and a power supply unit that performs one or both of conversion of input electric signals into electric signals used for an image forming operation and distribution of the converted electric signals. The power supply unit is arranged in a space vertically below the endless belt-like body and held between the first side plate and the second side plate.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an image forming apparatus in which a plurality of image forming units are arranged in a horizontal line vertically above an endless belt and an image is formed on the endless belt.

  There are image forming apparatuses in which a plurality of image forming units are arranged and a multicolor image is formed by direct transfer or indirect transfer on an endless belt. The image forming apparatus has a power supply unit, and converts an electric signal of a commercial power supply into an electric signal corresponding to each of electric parts and an image forming process and distributes the electric signal.

  In recent years, there has been a demand for downsizing of an image forming apparatus, and a power supply unit is disposed in a deep space inside the image forming apparatus. Such a space has a problem that ventilation is poor and heat generated by the power supply unit cannot be exhausted.

  In order to solve such a problem, Patent Document 1 discloses a configuration in which a fan and a duct are arranged to exhaust heat from a power supply unit. In Example 2 of Patent Document 2, a configuration in which a power supply unit is arranged on the side of an endless belt in an image forming apparatus in which a plurality of image forming units are arranged in the vertical direction and a fixing device is arranged on the upper side thereof is disclosed. Has been.

Japanese Patent No. 5233389 Patent No. 4069953

  However, in the configuration described in Patent Document 1, since the fan and the duct are arranged, the image forming apparatus is increased in size. Moreover, since the structure described in Patent Document 2 is a structure in which a plurality of image forming units are arranged in the vertical direction, the height (the height in the vertical direction) is high. Further, when the recording material is stored horizontally in the paper feed tray, the installation area of the image forming apparatus cannot be made smaller than the size of the recording material, so that the image forming apparatus is increased in size by the height.

  In order to reduce the size of the image forming apparatus, an “upside-down horizontal tandem configuration” image forming apparatus in which a plurality of image forming units are arranged horizontally and vertically above an endless belt is suitable.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to achieve both the downsizing of an image forming apparatus and the exhaust heat of a power supply unit in an image forming apparatus having an upward horizontal tandem configuration.

  In order to achieve the above object, the present invention provides an image forming apparatus in which a plurality of image forming units are arranged in a horizontal direction vertically above an endless belt that is stretched and conveyed by a plurality of rotating bodies. A first side plate that supports one end of the rotating body, a second side plate that faces the first side plate via the endless belt and supports the other end of the plurality of rotating bodies; A power supply unit that converts and / or distributes an input electrical signal to an electrical signal used for an image forming operation, and the power supply unit is vertically below the endless belt, and the first side plate And a space between the second side plates.

  According to the present invention, in the image forming apparatus in which a plurality of image forming units are arranged horizontally above the endless belt, it is possible to achieve both downsizing of the image forming apparatus and exhaust heat of the power supply unit.

1 is a schematic cross-sectional view of an image forming apparatus according to Embodiment 1. FIG. FIG. 2 is a schematic cross-sectional view of the image forming apparatus shown in FIG. 1 is a schematic cross-sectional view of a direct transfer type image forming apparatus according to Embodiment 1. FIG. 1 is a schematic sectional view of an image forming apparatus having a top plate according to Embodiment 1. FIG. FIG. 5 is a schematic cross-sectional view of the image forming apparatus shown in FIG. FIG. 4 is a schematic cross-sectional view of an image forming apparatus according to a second embodiment. FIG. 7 is a schematic cross-sectional view of the image forming apparatus shown in FIG. FIG. 6 is a schematic cross-sectional view of an image forming apparatus according to a third embodiment. FIG. 9 is a schematic cross-sectional view of the image forming apparatus shown in FIG.

  Hereinafter, preferred embodiments of the present invention will be illustrated with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in the following examples should be changed as appropriate according to the configuration of the apparatus to which the present invention is applied and various conditions. It is not intended to limit the scope of the invention to the following examples.

  In addition, the vertical direction and the horizontal direction in the following examples are directions when the image forming apparatus described in this example is installed on a horizontal plane, and when installed on an inclined surface, the directions with the inclined surface as a horizontal reference are set. Represent.

[Example 1]
(Configuration of image forming apparatus)
FIG. 1 is a schematic cross-sectional view of the image forming apparatus according to the present embodiment. FIG. 2 is a schematic cross-sectional view of the image forming apparatus viewed from the cutting line A in FIG. In FIGS. 1 and 2, only the structure is cut, and the unit and the roller are not cut.

  The image forming apparatus 1 is a multicolor image forming apparatus having an “upside-down horizontal tandem configuration” in which a plurality of image forming units are arranged in a horizontal direction vertically above an endless belt. The intermediate transfer belt 8 as an endless belt is stretched between a plurality of horizontally arranged tension rollers 9 and secondary transfer inner rollers 10. Image forming portions SY, SM, SC, and SK for forming images of yellow (Y), magenta (M), cyan (C), and black (K) are horizontally above the intermediate transfer belt 8. Arranged in a row. In this embodiment, the configuration and operation of the image forming units SY, SM, SC, and SK are substantially the same except that the color of the image to be formed is different. Therefore, unless otherwise distinguished, the subscripts Y, M, C, and K given to the reference numerals to indicate the elements provided for any color will be omitted.

On the inner peripheral surface side of the intermediate transfer belt 8, four primary transfer rollers 6 are arranged to face the respective photosensitive drums 2 included in the four image forming units SY, SM, SC, and SK. Then, the primary transfer roller 6 is pressed toward the photosensitive drum 2 with the intermediate transfer belt 8, thereby forming a primary transfer portion at a position where the intermediate transfer belt 8 and the photosensitive drum 2 come into contact with each other. The primary transfer roller 6 is applied with a voltage having a polarity opposite to the normal charging polarity of the toner from the power supply unit 21. The intermediate transfer belt 8 stretched between the tension roller 9 and the secondary transfer inner roller 10 is conveyed in the direction of arrow C. The intermediate transfer belt 8 is a base layer having a volume resistance of 1 × 10 ⁶ Ωcm and a thickness of 100 μm made of a conductive resin in which carbon black is dispersed in polyphenylene sulfide (PPS) resin. It is a two-layer endless belt-like body to which a surface layer having a volume resistance of 1 × 10 ¹⁴ Ωcm and a thickness of 1.5 μm is added.

  The image forming unit S has a photoconductive drum 2 rotating in the direction of arrow B as a center, and a charging roller 3, an exposure device 4, a developing device 5, and a cleaning blade 7 are arranged around the photosensitive drum 2. Has been. The charging roller 3 is a charging unit that uniformly charges the surface of the photosensitive drum 2. The exposure device 4 is an exposure unit that irradiates a laser beam based on image information transmitted from a host device (not shown) to form an electrostatic latent image on the surface of the photosensitive drum 2. The developing device 5 is a developing means of a non-magnetic one-component developing system that develops the electrostatic latent image formed on the photosensitive drum 2. The cleaning blade 7 is a cleaning unit that removes toner remaining on the surface of the photosensitive drum 2 after the toner image (developer image) formed on the photosensitive drum 2 is copied. A voltage having the same polarity as the normal charging polarity of the toner is applied to the charging roller 3, and a voltage having the same polarity as the normal charging polarity of the toner is applied to the developing device 5 from the power supply unit 21.

  The secondary transfer outer roller 11 is disposed on the outer peripheral surface side of the intermediate transfer belt 8 at a position facing the secondary transfer inner roller 10. By pressing the secondary transfer inner roller 10 with the secondary transfer outer roller 11 through the intermediate transfer belt 8, the secondary transfer portion N is formed at a position where the intermediate transfer belt 8 and the secondary transfer outer roller 11 come into contact with each other. To do. Further, a voltage having a polarity opposite to the normal charging polarity of the toner is applied from the power supply unit 21 to the secondary transfer outer roller 11. An intermediate transfer belt cleaning device 15 for cleaning the intermediate transfer belt 8 is attached downstream of the secondary transfer portion N with respect to the circumferential conveyance direction of the intermediate transfer belt 8.

  A paper feed unit 16 is disposed vertically below the intermediate transfer belt 8. The paper feed unit 16 includes a paper feed tray 17, a paper feed roller 18, a separation pad 19, and a registration roller pair 20. The paper feed tray 17 is a recording material stacking unit that is provided in the lower part of the image forming apparatus 1 and stores the recording material P in a stacked manner. The paper feed roller 18 is a recording material feeding unit that picks up and conveys the recording material P loaded on the paper feed tray 17. The separation pad 19 is a separation unit that is disposed to face the paper feed roller 18 and separates the recording materials picked up by the paper feed roller 18 one by one. The registration roller pair 20 is a recording material supply unit that is disposed on the paper feed path and temporarily stops the recording material and sends it to the intermediate transfer belt 8 at a predetermined timing. The registration roller pair 20 is provided vertically below an exhaust port 25 described later in the vertical direction.

  A fixing device 12 is disposed above the secondary transfer outer roller 11. The fixing device 12 includes a heating roller 13 and a pressure roller 14. The heating roller 13 has a heating source connected to the power supply unit 21 and presses the pressure roller 14 against the heating roller 13 to form a fixing nip.

  The power supply unit 21 and the electrical board 22 are arranged in a space between a drive side plate 26 as a first side plate and an electrical side plate 29 as a second side plate, which will be described later, below the intermediate transfer belt 8. The power supply unit 21 is a unit in which an electric component is attached to a board on which wiring is printed, and is housed in a housing. The power supply unit 21 converts an electrical signal input from an external commercial power source or the like into an electrical signal suitable for each part of the image forming apparatus, and distributes the electrical signal by controlling conduction interruption. The electric parts generate heat during operation, and a heat radiating plate is attached to an electric part having a large heat generation amount. Moreover, a part of heat sink is couple | bonded with the housing | casing. The electrical components of the power supply unit 21 are radiated from the casing or from an opening provided in the casing. Further, the power supply unit 21 may not have a casing. In this case, heat is directly dissipated from the electrical component and the heat sink attached thereto.

  The power supply unit 21 controls the conduction interruption of the electric signal supplied from the commercial power supply and supplies it to the heating roller 13, and converts the electric signal supplied from the commercial power supply into a voltage used for the operation of the electrical components. Divided into a low-voltage power supply unit that distributes and converts the voltage supplied from the low-voltage power supply unit into a high voltage for each process (image forming operation) of charging, development, primary transfer, and secondary transfer. May be.

  In the present embodiment, the power supply unit 21 is an integration of a fixing power supply unit, a low voltage power supply unit, and a high voltage power supply unit. The low-voltage power supply unit cuts off the AC 100 V, 50 Hz input voltage from the commercial power supply and supplies it to the heating roller 13 in accordance with the temperature adjustment signal sent from the electrical board 22. The low-voltage power supply unit converts an AC 100V, 50 Hz input voltage from a commercial power supply into a DC 3.3V necessary for the operation of the electrical board 22 and a DC 24V necessary for the operation of the motor 27 and the high-voltage power supply unit. The high-voltage power supply unit boosts the DC 24V supplied from the low-voltage power supply unit and converts it to a DC high voltage supplied to the charging roller 3 and the developing device 5.

  The electrical board 22 controls the motor 27 and the like to control the printer operation, the control circuit on which the peripheral circuit is mounted, and the image information transmitted from the host device (not shown) as a laser of the exposure apparatus 4. It consists of an image processing circuit that converts light to a control signal. In this embodiment, the laser drive circuit is incorporated in the exposure apparatus 4, but may be integrated with the electrical board 22.

  The driving side plate 26 is a first side plate that supports one end of the tension roller 9 and the secondary transfer inner roller 10 that stretch the intermediate transfer belt 8. The electrical side plate 29 faces the drive side plate 26 with the intermediate transfer belt 8 interposed therebetween, and supports the other end of the tension roller 9 and the secondary transfer inner roller 10 that stretch the intermediate transfer belt 8. It is a side plate.

  The driving side plate 26 includes a motor 27 and a gear train 28 as a driving mechanism for transmitting a driving force. Here, the motor 27 is an out-rotor type DC brushless motor. The drive mechanism of the drive side plate 26 transmits power to the image forming units SY, SM, SC, SK, the intermediate transfer belt 8, the paper feed unit 16, and the fixing device 12. The drive mechanism of the drive side plate 26 also includes a solenoid (not shown) that switches power transmission to the paper feed roller 18 and an electromagnetic clutch (not shown) that controls the rotation of the registration roller pair 20. A wiring 23 for connecting the power supply unit 21 or the electrical board 22 and a unit that requires an electrical signal is attached to the electrical side plate 29.

  The drive side plate 26 and the electrical side plate 29 support the main structure of the image forming apparatus 1. That is, the image forming units SY, SM, SC, SK, the tension roller 9 that stretches the intermediate transfer belt 8, the secondary transfer inner roller 10, and the primary transfer roller 6 are on both sides of the drive side plate 26 and the electrical side plate 29. It is supported by. These coupling units are mounted on the paper feed unit 16. Further, a fixing device 12 is mounted on the coupling unit.

(Operation of image forming apparatus)
The operation of the image forming apparatus will be described. When an operation command is sent from a host device (not shown) such as a personal computer that is communicably connected to the image forming apparatus 1, the image forming apparatus 1 starts its operation.

  When the image forming operation is performed, the surface of the photosensitive drum 2 is uniformly charged by the charging roller 3. Next, the surface of the photosensitive drum 2 is scanned and exposed by the laser light emitted from the exposure device 4, whereby an electrostatic latent image is formed on the photosensitive drum 2 based on the image information. The electrostatic latent image formed on the photosensitive drum 2 is developed by supplying toner by the developing device 5. The toner image formed on the photosensitive drum 2 is transferred (primary transfer) to the intermediate transfer belt 8 by the voltage applied to the primary transfer roller 6 at the primary transfer portion. When forming a full-color image, the toner images are sequentially transferred in the image forming portions SY, SM, SC, and SK, so that the toner images of the respective colors are superimposed on the intermediate transfer belt 8.

  When a toner image is formed on the intermediate transfer belt 8, a signal is sent to a solenoid (not shown) for switching power transmission to the paper feeding unit 16 attached to the driving side plate 26, and the paper feeding roller 18 rotates. The recording material P in the paper feed tray 17 is picked up. The recording material P is separated into one sheet by friction with the separation pad 19 and abutted against the registration roller pair 20 whose rotation is stopped to correct the skew.

  The registration roller pair 20 controls the rotation of the registration roller pair 20 at the timing when the leading edge of the recording material P that has been corrected and stopped reaches the leading edge of the toner image on the intermediate transfer belt 8 and the secondary transfer portion N at the same time. A signal is sent to an electromagnetic clutch (not shown) to start rotation. As a result, the recording material P is conveyed by the registration roller pair 20 and enters the secondary transfer portion N. The toner image formed on the intermediate transfer belt 8 is secondarily transferred to the recording material P by the voltage applied to the secondary transfer outer roller 11. Thereafter, the recording material P onto which the toner image has been transferred is conveyed to the fixing device 12. The recording material P is heated while being pressed by the fixing device 12 to fix the toner image. The recording material P on which the image is fixed is discharged and stacked on the upper part of the image forming apparatus. The toner remaining on the photosensitive drum 2 after the primary transfer is removed by the cleaning blade 7. Further, the secondary transfer residual toner remaining on the intermediate transfer belt 8 after the secondary transfer process is removed by the intermediate transfer belt cleaning device 15.

  Here, the specification in the image forming apparatus 1 is not limited to the above-described configuration for the purpose of the present invention.

  In the image forming apparatus 1 having the above-described horizontal tandem configuration, the image forming units SY, SM, SC, and SK and the intermediate transfer belt cleaning device 15 are arranged in the horizontal direction on the intermediate transfer belt 8, and the units of these units are arranged. Both side surfaces are supported by side plates 26 and 29. For this reason, it is possible to arrange and hold the unit in a small size and with high rigidity. Further, when the non-magnetic one-component developing method with few components is used as the developing device 5, the size is reduced. Further, in the case of an upside-down horizontal tandem configuration, gravity can be used for toner conveyance in the developing device 5 of the non-magnetic one-component developing system, so that a toner feeding mechanism is not required and the developing device 5 can be further reduced in size.

(Power supply unit placement)
In the small top horizontal tandem configuration of the present embodiment, the driving side plate 26 and the electrical side plate 29 support the main structure of the image forming apparatus 1 such as the intermediate transfer belt 8, and the coupling unit is connected to the paper feeding unit 16. It is the structure piled up on the top. For this reason, there is a space between the sheet feeding tray 17 and the intermediate transfer belt 8 in the vertical direction and a portion sandwiched between the drive side plate 26 and the electrical side plate 29 in the horizontal direction perpendicular to the vertical direction. The height of this space is larger than the height of the diameter of the paper feed roller 18. If the diameter of the paper feed roller 18 is reduced in order to reduce the size of the printer, the contact area with the recording material P is reduced during pick-up, so that the paper feed performance is degraded. Therefore, the diameter of the paper feed roller 18 cannot be reduced. Therefore, the power supply unit 21 is disposed in this space for the purpose of reducing the size of the image forming apparatus. Further, both the paper feed roller (recording material supply unit) 18 and the power supply unit 21 intersect the same plane parallel to the lower surface of the intermediate transfer belt 8 in the space between the drive side plate 26 and the electrical equipment side plate 29. Is provided.

  The power supply unit 21 converts the voltage of the commercial power supply into a voltage suitable for each electrical component, and controls conduction interruption. With these conversions and controls, the electrical components generate heat, and the power supply unit 21 rises in temperature. If the temperature of the electrical components constituting the power supply unit 21 rises too much, it causes performance degradation and failure, so it is necessary to exhaust heat. In many image forming apparatuses, the power supply unit 21 is disposed near the exterior including an air inlet, and exhausts heat by taking in outside air by natural convection. On the other hand, when the power supply unit 21 is arranged in the space inside the image forming apparatus, the heat generated by the power supply unit 21 is trapped and the power supply unit 21 is heated. As a countermeasure, a fan and a duct for introducing outside air to the power supply unit 21 can be arranged to exhaust heat, but this is contrary to downsizing of the apparatus.

  In this embodiment, the power supply unit 21 is arranged in a space between the drive side plate 26 and the electrical equipment side plate 29 vertically below the intermediate transfer belt 8. In addition, in the circumferential conveyance direction (arrow C direction) on the vertical lower surface of the intermediate transfer belt 8, an intake port 24 is disposed upstream from the power supply unit 21, and an exhaust port 25 is disposed downstream. The heat generated by the power supply unit 21 becomes an ascending current (arrow D) due to convection and accumulates in the lower portion of the intermediate transfer belt 8. However, when the intermediate transfer belt 8 is conveyed in a circular manner (arrow C), surface wind blows on the surface of the intermediate transfer belt 8 due to the viscosity of the air. By this surface wind, the outside air is sucked from the intake port 24 (arrow E). The intermediate transfer belt 8, the drive side plate 26, and the electrical side plate 29 form a duct, and hot air flows toward the secondary transfer outer roller 11 along the circumferential conveyance direction on the lower surface of the intermediate transfer belt 8. Then, hot air is exhausted (arrow F) from the exhaust port 25 formed under the secondary transfer outer roller 11. Further, the heat generated by the power supply unit 21 warms the intermediate transfer belt 8. The warmed intermediate transfer belt 8 comes into contact with the recording material P during the secondary transfer, and is cooled by transferring heat to the recording material P. Thus, the heat generated by the power supply unit 21 is also exhausted to the recording material P.

  As described above, in this embodiment, the heat generated by the power supply unit 21 is exhausted by the intermediate transfer belt 8, thereby making it possible to achieve both the downsizing of the image forming apparatus 1 and the exhaust heat of the power supply unit 21.

(Direct transfer method)
In this embodiment, as shown in FIG. 1, indirect transfer is performed in which the toner images of the respective colors formed on the photosensitive drum 2 are sequentially superimposed on the intermediate transfer belt 8 to form a full-color image and then secondarily transferred onto the recording material P. Applied to the scheme. However, the present invention can also be applied to a direct transfer system as shown in FIG. In the direct transfer method, the recording material P is conveyed to the recording material conveyance belt 30 as an endless belt, and the toner image is directly transferred directly from the photosensitive drum 2 of the image forming unit SY. Then, primary transfer is sequentially performed from the image forming units SM, SC, and SK, and a full-color image is formed on the recording material P. The material adhering to the recording material conveyance belt 30 is removed by the recording material conveyance belt cleaning device 31. Other configurations are the same as those of the indirect transfer method, and a description thereof will be omitted. In the direct transfer image forming apparatus shown in FIG. 3, the same or similar parts as those in the indirect transfer image forming apparatus shown in FIG.

(Toner adheres to the power supply unit)
Various electric signals flow through the power supply unit 21, and the surface potential depends on those electric signals. The charged toner may adhere to the power supply unit 21 by being attracted to these surface potentials. This is particularly noticeable when the power supply unit 21 is not housed in the housing. Since the base layer of the intermediate transfer belt 8 of this embodiment is a conductive resin (conductive layer) having a volume resistance of 1 × 10 ⁶ Ωcm, the surface potential of the intermediate transfer belt 8 is around the voltage applied to the primary transfer roller 6. Almost equal. Then, an electric field is generated between the intermediate transfer belt 8 and the power supply unit 21 at a position where the intermediate transfer belt 8 and the power supply unit 21 face each other. Since the intermediate transfer belt 8 has a voltage having a polarity opposite to the normal charging polarity of the toner, the charged toner has a force toward the intermediate transfer belt 8 from a portion of the power supply unit 21 having a lower surface potential than the intermediate transfer belt 8. Receive. This force can reduce the adhesion of charged toner to the power supply unit 21.

When a single layer belt having a volume resistance of 1 × 10 ⁹ Ωcm or more is used as the intermediate transfer belt 8, the intermediate transfer belt 8 becomes a floating potential at a position where the intermediate transfer belt 8 and the power supply unit 21 face each other. In this case, the force of charged toner from the power supply unit 21 toward the intermediate transfer belt 8 does not work.

  As described above, in this embodiment, the use of a conductor as the intermediate transfer belt 8 can reduce the adhesion of charged toner to the power supply unit 21. Here, as the intermediate transfer belt 8, a multilayer body (two layers) of a conductor having a conductive layer is illustrated, but a single layer or a multilayer body of three or more layers may be used as long as the conductor has at least a conductive layer. Good.

  Further, it is only necessary that an ascending airflow (arrow D) due to heat generated by the power supply unit 21 can pass between the intermediate transfer belt 8 and the power supply unit 21. As shown in FIGS. Between them, a grounding punching metal top plate 32 may be installed. FIG. 4 is a schematic cross-sectional view when the top plate 32 is attached to the image forming apparatus according to the first embodiment. FIG. 5 is a schematic cross-sectional view seen from the cutting line G in FIG.

  The surface potential of the power supply unit 21 is shielded by the top plate 32. For this reason, even when no conductor is used for the intermediate transfer belt 8, the charged toner is attracted to the top plate 32, so that adhesion to the power supply unit 21 can be reduced. Further, when no conductor is used for the intermediate transfer belt 8, the charged toner receives a force from the power supply unit 21 toward the intermediate transfer belt 8 due to an electric field generated between the intermediate transfer belt 8 and the grounded top plate 32. Therefore, the adhesion of charged toner to the power supply unit 21 can be further reduced. Here, although the top plate 32 is grounded, a voltage having the same polarity as the normal charging polarity of the toner may be applied by insulatingly supporting the top plate 32 so as not to attract the charged toner. The top plate 32 of punching metal is disposed as the top plate. However, the top plate 32 may be any air-permeable conductive member, and a conductive member having an opening such as a wire net or grating is applicable.

[Example 2]
The configuration of the present embodiment is basically the same as that of the image forming apparatus of the first embodiment, but the following points are different. In addition, the same code | symbol is attached | subjected to the part which is the same as that of Example 1, or similar, and the overlapping description is abbreviate | omitted.

  FIG. 6 is a schematic cross-sectional view of the image forming apparatus according to the present embodiment. FIG. 7 is a schematic cross-sectional view seen from the cutting line H in FIG. 6 and 7 cut only the structure, and the units and rollers are not cut.

  In this embodiment, exhaust ports 35 and 36 are provided on both side surfaces of the image forming apparatus 1. The exhaust ports 35 and 36 are provided outside the recording material conveyance area. Further, a deflection plate 34 is provided along the intermediate transfer belt 8 from the power supply unit 21 toward the exhaust ports 35 and 36. The deflection plate 34 is provided on the downstream side of the power supply unit 21 between the intermediate transfer belt 8 and the power supply unit 21 in the vertical direction and along the moving direction (arrow C) of the intermediate transfer belt 8. In FIG. 7, the outside of the recording material conveyance area is outside the nip area between the secondary transfer inner roller 10 and the secondary transfer outer roller 11.

  In the first exemplary embodiment, when the image forming apparatus 1 secondarily transfers the toner image on the intermediate transfer belt 8 to the recording material P, the recording material P exists on the inlet side of the secondary transfer portion N, and the recording material The surface wind (arrow F) of the intermediate transfer belt 8 toward the exhaust port 25 is blocked by P. Therefore, in the configuration of Example 1, the time during which exhaust can be performed is limited, and the exhaust efficiency is reduced. In the present embodiment, the surface wind of the intermediate transfer belt 8 is deflected by the deflection plate 34 toward the outside of the recording material conveyance area as indicated by arrows I1 and I2, and exhausted from the exhaust ports 35 and 36 on the side surface of the apparatus. . Thereby, the hot air of the power supply unit 21 can always be exhausted without being blocked by the recording material P.

  As described above, in this embodiment, the exhaust efficiency can be increased by arranging the deflection plate 34.

Example 3
The configuration of the present embodiment is basically the same as that of the image forming apparatus of the first embodiment, but the following points are different. In addition, the same code | symbol is attached | subjected to the part which is the same as that of Example 1, or similar, and the overlapping description is abbreviate | omitted.

  FIG. 8 is a schematic cross-sectional view of the image forming apparatus according to the present embodiment. FIG. 9 is a schematic cross-sectional view seen from the cutting line J in FIG. 8 and 9 cut only the structure, and the units and rollers are not cut.

  In the present embodiment, as in the first and second embodiments, the air inlet 24 is disposed on the upstream side of the power supply unit 21 in the circumferential conveyance direction (arrow C direction) on the vertical lower surface of the intermediate transfer belt 8. Also, in this embodiment, unlike the embodiment described above, the surface wind of the intermediate transfer belt 8 blocks the path toward the secondary transfer portion N. Instead, the fin 37 is attached to the motor 27 as a rotating member that forms part of the drive mechanism of the drive side plate 26 on the downstream side of the power supply unit 21 in the circumferential conveyance direction (arrow C direction) of the vertical lower surface of the intermediate transfer belt 8. Is attached. Further, an exhaust port 38 that faces the fins 37 is disposed on the electrical side plate 29 side that faces the drive side plate 26. A projection line K in FIG. 8 represents the projection position of the motor 27 attached to the drive side plate 26.

  As described in the second embodiment, in the first embodiment, there is a time zone in which the surface wind (arrow F) of the intermediate transfer belt 8 toward the exhaust port 25 is blocked by the recording material P, and the exhaust efficiency is reduced. .

  In this embodiment, the hot air accumulated on the downstream side of the power supply unit 21 along the conveyance direction (arrow C) of the intermediate transfer belt 8 due to the surface wind of the intermediate transfer belt 8 is transferred to the fins 37 attached to the rotor of the motor 27. Due to the airflow generated, the air is exhausted from the exhaust port 38 on the electrical equipment side plate 29 side as indicated by the arrow L. Thus, the surface air (arrow F) of the intermediate transfer belt 8 is not blocked by the recording material P, and the hot air of the power supply unit 21 can always be exhausted.

  As described above, in this embodiment, the exhaust efficiency can be increased by attaching the fins 37 to the rotor of the motor 27.

  In the present embodiment, the fins 37 are attached to the rotor of the motor 27. However, the fins may be attached to other parts as long as they rotate, and may be included in the gear train 28 as a rotating member forming a part of the driving side plate 26. It is good also as a structure which attached the fin.

[Other Examples]
In the above-described embodiment, the configuration having four different color image forming units as the plurality of image forming units included in the image forming apparatus is illustrated. However, the number of colors, the number of colors, and the number used are not limited. It may be set appropriately as necessary.

  In the above-described embodiments, the printer is exemplified as the image forming apparatus, but the present invention is not limited to this. For example, the image forming apparatus may be another image forming apparatus such as a copying machine or a facsimile machine, or another image forming apparatus such as a multi-function machine combining these functions, and the same applies by applying the present invention to the image forming apparatus. The effect of can be obtained.

N: Secondary transfer section P: Recording material S, SY, SM, SC, SK ... Image forming section 1 ... Image forming apparatus 2 ... Photoconductor drum 8 ... Intermediate transfer belt 9 ... Tension roller 10 ... Secondary transfer inner roller 11 ... secondary transfer outer roller 16 ... paper feed unit 17 ... paper feed tray 18 ... paper feed roller 19 ... separation pad 20 ... registration roller pair 21 ... power supply unit 22 ... electrical equipment board 23 ... wiring 24 ... air inlets 25, 35, 36, 38 ... exhaust port 26 ... drive side plate 27 ... motor 28 ... gear train 29 ... electrical equipment side plate 30 ... recording material transport belt 32 ... top plate 34 ... deflection plate 37 ... fin

Claims (9)

In an image forming apparatus in which a plurality of image forming units are arranged in a horizontal direction vertically above an endless belt that is stretched around a plurality of rotating bodies and is conveyed around,
A first side plate that supports one end of the plurality of rotating bodies;
A second side plate facing the first side plate via the endless belt and supporting the other end of the plurality of rotating bodies;
A power supply unit that converts an input electric signal into an electric signal used for an image forming operation and / or distributes the electric signal;
An image forming apparatus, wherein the power supply unit is arranged in a space between the first side plate and the second side plate, vertically below the endless belt. A recording material stacking unit provided at a lower portion of the image forming apparatus and configured to stack a recording material;
A recording material supply unit for supplying a recording material from the recording material stacking unit,
The power supply unit is disposed between the first side plate and the second side plate and in a space between the endless belt and the recording material stacking unit. Image forming apparatus.   The image forming apparatus according to claim 2, wherein both the recording material supply unit and the power supply unit intersect with the same plane parallel to the lower surface of the endless belt.   4. The intake port is disposed upstream of the power supply unit and the exhaust port is disposed downstream of the power supply unit in the circumferential conveyance direction of the vertical lower surface of the endless strip. 4. The image forming apparatus described in 1.   5. The registration roller pair according to claim 4, further comprising a registration roller pair that stops the recording material and sends the recording material to the endless belt at a predetermined timing, and the registration roller pair is provided vertically below the exhaust port in the vertical direction. Image forming apparatus. While providing the exhaust port outside the recording material conveyance area,
The image forming apparatus according to claim 4, wherein a deflecting plate is disposed along the endless belt from the power supply unit toward the exhaust port. In the circumferential conveyance direction of the vertical lower surface of the endless belt, an intake port is arranged on the upstream side of the power supply unit,
The first side plate has a driving mechanism for transmitting a driving force,
A fin is provided on a rotating member forming a part of the drive mechanism on the downstream side of the power supply unit in the circumferential conveyance direction of the vertical lower surface of the endless belt, and an exhaust port is provided in the second side plate facing the fin. The image forming apparatus according to claim 1, wherein the image forming apparatus is arranged.   The endless belt-like body is a single layer or a multilayer body, has at least a conductive layer, and has a voltage opposite in polarity to the toner at a position facing the power supply unit. The image forming apparatus described in the item.   The image forming apparatus according to claim 1, further comprising a conductive member having air permeability between the endless belt and the power supply unit.

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