JP5288763B2 - Intermediate transfer unit and color image forming apparatus having the same - Google Patents

Description

  The present invention relates to an intermediate transfer unit in which a toner conveyance path for transferring toner from a toner container to a developing device is formed, and a color image forming apparatus including the intermediate transfer unit.

  In a color image forming apparatus such as a color copying machine or a color printer that forms a color image on paper by electrophotography, toner images formed on a plurality of image carriers arranged in tandem are transferred by an intermediate transfer unit. A color image is formed by sequentially superimposing and transferring the image onto a belt and transferring the toner image transferred onto the intermediate transfer belt onto a sheet. The paper on which the color image has been transferred is conveyed to a fixing device, where the color image is fixed by heat and pressure by the fixing device, and then discharged out of the machine to complete a series of image forming processes. To do.

  Incidentally, in a color image forming apparatus in which an intermediate transfer unit is arranged between a plurality of toner containers and a plurality of developing devices disposed below the toner containers, toner for supplying toner from the toner containers to the developing devices is provided. A supply pipe is provided around the outer side of the intermediate transfer unit (see Patent Document 1). For this reason, the image forming apparatus is increased in size. In particular, in the color image forming apparatus, since the position of the toner replenishing port is not equal to each developing device, the length and shape of the toner supply pipe are different for each color, and the intermediate transfer There was a problem that the detachability of the unit was bad and the cost was increased.

Therefore, a configuration in which a toner conveyance path connecting the toner container and the developing device is formed in the intermediate transfer unit is adopted, and according to this, the toner received from the toner container at the toner inlet that is the upper opening of the toner conveyance path is used. Since the toner exits from the toner outlet, which is the lower opening of the toner transport path, toward the developing device through the toner transport path, the above problem is solved.
JP 2004-139031 A

  However, in the intermediate transfer unit in which the toner conveyance path is formed, if the toner inlet is always open, there is a problem that the toner is scattered at the toner inlet when the toner container is attached and detached, and the surroundings are contaminated.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide an intermediate transfer unit capable of preventing scattering of toner when the toner container is attached and detached, and a color image forming apparatus including the intermediate transfer unit. is there.

In order to achieve the above object, a first aspect of the present invention provides a plurality of detachable toner containers arranged in parallel in a main body of a color image forming apparatus, and a plurality of image carriers arranged in parallel below. A traveling endless intermediate transfer belt is disposed in the middle in the vertical direction of the developing device, and the toner images of each color formed on the plurality of image carriers are sequentially primary-transferred. A unit for secondary transfer of a transferred toner image onto a sheet, wherein a plurality of toner inlets for receiving toner from the respective toner containers are formed on an upper surface of the housing, and the toners received from the toner inlets are the toner outlet for discharging toward the developing devices so as to form the lower surface of the housing, in the intermediate transfer unit obtained by forming a toner conveying path connecting with these toner inlet and toner outlet in the housing Characterized by providing an inlet shutter for opening and closing the respective toner inlet in conjunction with the attachment and detachment operation of the respective toner container.

  According to a second aspect of the present invention, in the first aspect of the present invention, the upper surface of the entrance shutter has an inclined surface, and the toner container can be temporarily held on the inclined surface at a position higher than the mounting position.

  The invention according to claim 3 is the invention according to claim 1 or 2, wherein the entrance shutter is urged toward the closing side by the urging means, and the engagement surface of the entrance shutter with the toner container is an inclined surface, The toner container is configured to be pressed in the mounting direction by a component force of an urging force acting on the toner container via the engagement surface of the entrance shutter when the toner container is mounted.

  According to a fourth aspect of the present invention, there is provided an outlet shutter according to any one of the first to third aspects, wherein an outlet shutter is provided for simultaneously opening and closing all the toner outlets in conjunction with the attaching / detaching operation of the toner container. To do.

  An image forming apparatus according to a fifth aspect includes the intermediate transfer unit according to any one of the first to fourth aspects.

  According to the first aspect of the present invention, each toner inlet of the intermediate transfer unit is opened by the entrance shutter in conjunction with the mounting operation of each toner container, and each toner of the intermediate transfer unit is interlocked with the removal operation of each toner container. Since the inlet is closed, the scattering of the toner when the toner container is attached / detached can be surely prevented.

  According to the second aspect of the present invention, since the toner container can be temporarily held at a position higher than the mounting position on the slope formed on the upper surface of the entrance shutter, the coupling between the toner container and the main body side does not match. In addition, the occurrence of problems such as damage to the coupling claws is prevented.

  According to the third aspect of the present invention, when the toner container is mounted, the toner container is pressed in the mounting direction by the component force of the biasing force acting on the toner container via the engagement surface of the entrance shutter of the intermediate transfer unit. Since the toner container is configured as described above, the toner container can be securely attached and prevented from falling off.

  According to the fourth aspect of the present invention, since all the toner outlets of the intermediate transfer unit are simultaneously opened and closed by the outlet shutter in conjunction with the attaching / detaching operation of the toner container, the scattering of the toner when the toner container is attached / detached can be more reliably prevented. Can be removed.

  According to the fifth aspect of the present invention, in the color image forming apparatus, the toner is prevented from being scattered when the toner container is attached / detached, and problems such as contamination of the inside of the apparatus main body due to the toner scattering do not occur.

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

[Color image forming apparatus]
FIG. 1 is a front sectional view of a color image forming apparatus according to the present invention. The color image forming apparatus is a tandem type, and a magenta image forming unit 1M and a cyan image forming unit 1C are provided at the center of the main body 100. The yellow image forming unit 1Y and the black image forming unit 1BK are arranged in tandem at regular intervals.

  The image forming units 1M, 1C, 1Y, and 1BK are provided with photosensitive drums 2a, 2b, 2c, and 2d, respectively, and around the photosensitive drums 2a to 2d, chargers 3a, 3b, 3c, 3d, developing devices 4a, 4b, 4c and 4d, transfer rollers 5a, 5b, 5c and 5d as transfer means, and drum cleaning devices 6a, 6b, 6c and 6d are arranged, respectively.

  Here, the photosensitive drums 2a to 2d are drum-shaped photosensitive members, and are rotationally driven at a predetermined process speed in a direction indicated by an arrow (clockwise) by a variable speed stepping motor (not shown). The chargers 3a to 3d uniformly charge the surfaces of the photosensitive drums 2a to 2d to a predetermined potential by a charging bias applied from a charging bias power source (not shown).

  Further, the developing devices 4a to 4d contain magenta (M) toner, cyan (C) toner, yellow (Y) toner, and black (BK) toner, respectively, and are formed on the respective photosensitive drums 2a to 2d. In addition, the toner of each color is attached to each electrostatic latent image to visualize each electrostatic latent image as a toner image of each color.

  The transfer rollers 5a to 5d as transfer means are arranged so as to be in contact with the photosensitive drums 2a to 2d through the intermediate transfer belt 7 of the intermediate transfer unit 50 according to the present invention at each primary transfer portion. Yes. Here, the intermediate transfer belt 7 is stretched between the secondary transfer counter roller 8 and the tension roller 9 and is disposed on the upper surface side of each of the photosensitive drums 2a to 2d. The roller 8 is disposed so as to be in contact with the secondary transfer roller 10 via the intermediate transfer belt 7 in the secondary transfer portion. A belt cleaning device 11 is provided in the vicinity of the tension roller 9. As a material for the intermediate transfer belt 7, for example, a dielectric resin such as polycarbonate, polyethylene terephthalate (PET), polyvinylidene fluoride (PVDF), or the like is selected.

  Incidentally, toner containers 12a, 12b, 12c and 12d for supplying toner to the developing devices 4a to 4d are arranged in a line above the image forming units 1M, 1C, 1Y and 1BK in the apparatus main body 100. The intermediate transfer unit 50 is disposed below the toner containers 12a, 12b, 12c, and 12d.

  In addition, a laser scanner unit (LSU) 13 is disposed below the image forming units 1M, 1C, 1Y, and 1BK in the apparatus main body 100, and a paper feed cassette 14 is detachably attached to the bottom of the main body 100 below the image forming units. is set up. A plurality of sheets (not shown) are stacked and accommodated in the paper feed cassette 14, and a pickup roller 15 for taking out the paper one by one from the paper feed cassette 14 is taken out in the vicinity of the paper feed cassette 14. A feed roller 16 and a retard roller 17 are provided for feeding the fed paper to the transport path L.

  In addition, the conveyance path L extending in the vertical direction on the side of the apparatus main body 100 includes a conveyance roller pair 18 that conveys the sheet, and the secondary transfer counter roller 8 and the second transfer opposing roller 8 at a predetermined timing after the sheet is temporarily held. A registration roller pair 19 is provided to be supplied to a secondary transfer portion which is a contact portion with the next transfer roller 10. Next to the transport path L, another transport path L ′ used for forming an image on both sides of the sheet is formed, and a plurality of transport roller pairs 20 are appropriately used in the transport path L ′. Are provided at regular intervals.

  By the way, the conveyance path L arranged in the vertical direction on one side in the apparatus main body 100 extends to the paper discharge tray 21 provided on the upper surface of the apparatus main body 100, and the fixing device 22 and the discharge path are in the middle. A paper roller pair 23 and a paper discharge device 24 are provided.

  Next, an image forming operation by the color image forming apparatus having the above configuration will be described.

  When an image formation start signal is issued, the photosensitive drums 2a to 2d are driven to rotate at a predetermined process speed in the direction of the arrow in FIG. 1 (clockwise) in each of the image forming units 1M, 1C, 1Y, and 1BK. The drums 2a to 2d are uniformly charged by the chargers 3a to 3d. The laser scanner unit 13 emits a laser beam modulated by a color image signal for each color, irradiates the surface of each photosensitive drum 2a to 2d with the laser beam, and each color is applied to each photosensitive drum 2a to 2d. An electrostatic latent image corresponding to the color image signal is formed.

  First, magenta toner is attached to the electrostatic latent image formed on the photosensitive drum 2a of the magenta image forming unit 1M by the developing device 4a to which a developing bias having the same polarity as the charged polarity of the photosensitive drum 2a is applied. The electrostatic latent image is visualized as a magenta toner image. This magenta toner image is transferred to the arrow shown in FIG. 1 by the action of the transfer roller 5a to which a primary transfer bias having a polarity opposite to that of the toner is applied at the primary transfer portion (transfer nip portion) between the photosensitive drum 2a and the transfer roller 5a. Primary transfer is performed on the intermediate transfer belt 7 which is rotationally driven in the direction.

  The intermediate transfer belt 7 on which the magenta toner image has been primarily transferred as described above moves to the next cyan image forming unit 1C. In the cyan image forming unit 1C as well, the cyan toner image formed on the photosensitive drum 2b is transferred to the magenta toner image on the intermediate transfer belt 7 in the primary transfer portion in the same manner as described above.

  Similarly, yellow and black toners respectively formed on the photosensitive drums 2c and 2d of the yellow and black image forming units 1Y and 1BK on the magenta and cyan toner images superimposed and transferred on the intermediate transfer belt 7, respectively. The images are sequentially superimposed at each primary transfer portion, and a full-color toner image is formed on the intermediate transfer belt 7. The transfer residual toner which is not transferred onto the intermediate transfer belt 7 and remains on the photosensitive drums 2a to 2d is removed by the drum cleaning devices 6a to 6d, and the photosensitive drums 2a to 2d are prepared for the next image formation. It is done.

  Then, the pickup from the paper feed cassette 14 is performed in accordance with the timing at which the front end of the full color toner image on the intermediate transfer belt 7 reaches the secondary transfer portion (transfer nip portion) between the secondary transfer counter roller 8 and the secondary transfer roller 10. The sheet fed to the conveyance path L by the roller 15, the feed roller 16 and the retard roller 17 is conveyed to the secondary transfer unit by the registration roller pair 19. Then, a full-color toner image is collectively transferred from the intermediate transfer belt 7 to the sheet conveyed to the secondary transfer unit by the secondary transfer roller 10 to which a secondary transfer bias having a polarity opposite to that of the toner is applied. .

  Thus, the sheet on which the full-color toner image has been transferred is conveyed to the fixing device 22, and the sheet on which the full-color toner image has been fixed by being heated and pressurized and thermally fixed on the surface of the sheet. Then, the paper is conveyed to the paper discharge device 24 by the paper discharge roller pair 23 and is discharged onto the paper discharge tray 21 by the paper discharge device 24 to complete a series of image forming operations. The transfer residual toner that is not transferred onto the sheet and remains on the intermediate transfer belt 7 is removed by the belt cleaning device 11, and the intermediate transfer belt 7 is prepared for the next image formation.

[Intermediate transfer unit]
Next, an embodiment of the intermediate transfer unit 50 according to the present invention will be described.

<Embodiment 1>
2 is a perspective view of the intermediate transfer unit according to Embodiment 1 of the present invention, FIG. 3 is a perspective view showing the relationship between the toner container, the intermediate transfer unit, and the developing device, and FIG. 4 is a development from the toner container through the intermediate transfer unit. FIG. 5 is a partial cross-sectional perspective view showing a state where toner is supplied to the apparatus, FIG. 5 is a partial cross-sectional view showing delivery of toner from the toner container to the intermediate transfer unit, and FIG. 6 is a partial perspective view of the entrance shutter portion of the intermediate transfer unit. 7 is a partial perspective view of the developing device, FIGS. 8A and 8B are partial bottom views of the intermediate transfer unit, FIG. 9 is a partial perspective view showing the relationship between the outlet shutter of the intermediate transfer unit and the developing device, and FIG. FIG. 4 is a perspective view of an exit shutter.

    As shown in FIG. 2, the intermediate transfer unit 50 includes an endless intermediate transfer belt 7 that can run, and magenta (M), cyan (C), yellow (Y ) And black (BK) toner mounting portions 50a, 50b, 50c, and 50d for mounting the toner containers 12a, 12b, 12c, and 12d are juxtaposed in the longitudinal direction.

  Further, as shown in FIGS. 4 to 6, a rectangular hole is formed on the upper surface of the portion corresponding to each mounting portion 50a to 50d at one end in the width direction of the intermediate transfer unit 50 (front side in FIG. 2). A toner inlet 51 is opened, and a rectangular hole-shaped toner outlet 52 is formed on the lower surface of the portion corresponding to each mounting portion 50a to 50d of the casing, as shown in FIGS. 4, 5, and 8A. As shown in FIGS. 4 and 5, toner transport paths 53 for connecting the toner inlet 51 and the toner outlet 52 are formed in the mounting portions 50 a to 50 d, respectively. ing. As shown in FIGS. 4 and 5, a toner conveying screw 54 for transferring the toner introduced from each toner inlet 51 to each toner outlet 52 side is rotatable in the housing of the intermediate transfer unit 50. The toner conveying screw 54 is rotationally driven by a motor (not shown).

  Thus, as shown in FIGS. 3 and 4, each toner container (only the yellow toner container 12 c is shown in FIGS. 3 and 4) is attached to each attachment portion 50 a to 50 d of the intermediate transfer unit 50. A developing device for each color (only the yellow developing device 4c is shown in FIGS. 3 and 4) is disposed below the intermediate transfer unit 50. The toner containers 12a to 12d are disposed above the intermediate transfer unit 50. Inlet shutters 55 that open and close each toner inlet 51 by sliding in the longitudinal direction (in the direction of the arrow in FIG. 6) in conjunction with the attaching / detaching operation are provided.

  Here, as shown in detail in FIGS. 5 and 6, each entrance shutter 55 includes a cam member 55 </ b> A and a seal material 55 </ b> B. Each cam container 55 </ b> A has a toner container (yellow and yellow in FIG. 5). A sloped cam surface 55a for engaging the cylindrical portion of the black toner containers 12c and 12d is formed, and a toner injection port 55b having the same shape as the toner inlet 51 is formed in the sealing material 55B. . Each inlet shutter 55 is urged in a closing direction (a direction in which the seal material 55B closes the toner inlet 51) by a pair of left and right tension springs 56 as urging means, as shown in FIG.

  Incidentally, as shown in FIG. 6, on the left and right inner surfaces (only one inner surface is shown in FIG. 6) of the main body frame 100A, the mounting of the toner containers 12a to 12d in the vertical direction (arrow direction in FIG. 6) is guided. Vertical guide grooves 101 (only guide grooves for guiding cyan and yellow toner contents 12b and 12c are shown in FIG. 6) are respectively formed, and a concave shape is formed at the lower end of each guide groove 101. Each coupling 102 is provided. Each coupling 102 is connected by being fitted to a convex coupling 60 (see FIG. 5) provided in each of the toner containers 12a to 12d, so that the top cover 100a of the apparatus main body 100 shown in FIG. In conjunction with the opening / closing operation, the shutter rotates in the direction of the arrow in FIG. 6 to open / close shutters (not shown) of the toner containers 12a to 12d.

  Thus, as shown in FIGS. 3 to 5, for example, the yellow toner container 12c is moved vertically downward along the guide groove 101 of the main body frame 100A shown in FIG. 2), the cylindrical portion of the toner container 12c engages with the cam surface 55a of the cam member 55A of the entrance shutter 55 in the course of the mounting operation. Therefore, the entrance shutter 55 slides to the left in FIG. 5 against the biasing force of the tension spring 56, and the toner injection port 55b formed in the seal material 55B of the entrance shutter 55 is shown in FIGS. Thus, the toner inlet 51 is automatically opened in conjunction with the mounting operation of the toner container 12c. Each toner inlet 51 is also opened by each inlet shutter 55 by the mounting operation of the other toner containers 12a, 12b, 12d.

  When the toner container 12c is moved vertically downward along the guide groove 101 of the main body frame 100A shown in FIG. 6 and removed from the mounting portion 50c (see FIG. 2) of the intermediate transfer unit 50, the cylindrical portion of the toner container 12c. The engagement of the entrance shutter 55 with the cam member 55A is released. Therefore, the entrance shutter 55 slides to the right in FIG. 5 by the urging force of the tension spring 56, and the seal material 55B of the entrance shutter 55 closes the toner entrance 51, so that the toner entrance 51 performs the mounting operation of the toner container 12c. Automatically closes in conjunction. Even if the other toner containers 12 a, 12 b, 12 d are removed, the respective toner inlets 51 are closed by the respective inlet shutters 55.

  On the other hand, as shown in FIG. 7, the upper surface of each developing device (only the yellow developing device 4c is shown in FIG. 7) arranged below the intermediate transfer unit 50 is a rectangle that receives toner supply from the intermediate transfer unit 50. A hole-shaped toner supply port 57 is opened, and the toner supply port 57 is connected to a toner outlet 52 of the intermediate transfer unit 50 as shown in FIG.

  Thus, in the present embodiment, as shown in FIGS. 2 and 3, the toner containers 12 a to 12 b are arranged on one end surface in the width direction of the intermediate transfer unit 50 (the surface on the side where the entrance shutter 55 is provided). An outlet shutter 58 for simultaneously opening and closing all four toner outlets 52 is provided so as to be slidable in the longitudinal direction in conjunction with the attaching / detaching operation of 12d. The outlet shutter 58 is a tension spring 59 which is a biasing means. Is biased in the closing direction (the direction in which the toner outlet 52 is closed).

  Here, as shown in FIG. 10, the outlet shutter 58 is integrally formed with four L-shaped seal portions 58a for opening and closing each toner outlet 52 of the intermediate transfer unit 50, and the toner container 12a. In a state in which -12d is not attached, the four seal portions 58a of the outlet shutter 58 close all the toner outlets 52 of the intermediate transfer unit 50 as shown in FIG.

  Thus, when at least one of the toner containers 12a to 12d is mounted as described above, the exit shutter 58 slides in the direction of the arrow in FIG. 9 against the urging force of the tension spring 59 in conjunction with the mounting operation. The four seal portions 58a of the outlet shutter 58 simultaneously open all the toner outlets 52 of the intermediate transfer unit 50 as shown in FIG. 8A, and supply toner to these toner outlets 52 and the developing devices 4a to 4d. The mouth 57 (see FIG. 7) is connected simultaneously.

  As described above, each toner inlet 51 of the intermediate transfer unit 50 is opened by the inlet shutter 55 in conjunction with the mounting operation of the toner containers 12a to 12d, and all the toner outlets 52 of the intermediate transfer unit 50 are outlet shutters 58. 4 and 5, as shown in FIGS. 4 and 5, replenishment from each toner container (FIG. 4 shows only the yellow toner container 12c, and FIG. 5 shows only the yellow and black toner containers 12c and 12d). The toner is introduced into each toner inlet 51 of the intermediate transfer unit 50, passes through each toner conveyance path 53 as shown by an arrow, and passes through each toner discharge port 52 to each developing device (FIG. 4 shows a yellow developing device 4c). The toner is supplied to the toner replenishing port 57 (only shown) and replenished.

  Further, the toner inlets 51 of the intermediate transfer unit 50 are closed in conjunction with the removal operation of the toner containers 12a to 12d, and all the toner outlets 52 of the intermediate transfer unit 50 are simultaneously closed by the outlet shutters 58. When the containers 12a to 12d are attached and detached, the toner is surely prevented from scattering, the toner in the color image forming apparatus shown in FIG. 1 is prevented from being scattered, and the apparatus main body 100 is contaminated by the toner scattering. It does not occur.

  Further, in the present embodiment, even if the inlet shutter 55 is not interlocked with the attaching / detaching operation of the toner containers 12a to 12d, each toner inlet 51 of the intermediate transfer unit 50 can be opened and closed individually, so that the toner containers 12a to 12d can be replaced. Sometimes each toner inlet 51 is opened and closed one by one, and the toner outlet 52 of the intermediate transfer unit 50 is connected to the toner replenishment port 57 of each color developing device 4a to 4d except when the intermediate transfer unit is removed. Since the toner outlets 52 are simultaneously opened and closed by the single outlet shutter 58, the opening and closing control of the toner inlet 51 and the toner outlet 52 can be performed efficiently.

<Embodiment 2>
Next, a second embodiment of the present invention will be described with reference to FIGS.

  11 and 12 are partial perspective views showing a state in which the toner container is temporarily held on the entrance shutter of the intermediate transfer unit according to the second embodiment of the present invention, and FIG. 13 is a diagram showing that the toner container is mounted on the intermediate transfer unit. FIG. 14 is a partial perspective view showing the force acting on the toner container from the exit shutter when the toner container is mounted on the intermediate transfer unit. In these figures, FIGS. The same elements as those described above are denoted by the same reference numerals, and repetitive description thereof will be omitted below.

  In the present embodiment, the cam surface 55a on the upper surface of the cam member 55A of each entrance shutter 55 is a flat slope, and each toner container (only the cyan toner container 12b is shown in FIGS. 11 and 12). Can be temporarily held at a position higher than the mounting position. Further, in this embodiment, each inlet shutter 55 is biased to the closing side by a tension spring 56 as a biasing means, and a toner container of a cam member 55A of the inlet shutter 55 (FIG. 13 shows a cyan toner container). In the example shown in FIG. 13, when the toner container 12 b is mounted in the example shown in FIG. 13, the toner container 12 b is brought into contact with the toner container 12 b via the engagement surface 55 c of the entrance shutter 55, as shown in FIG. 14. The toner container 12b is configured to be pressed in the mounting direction (vertically downward) by a vertical component force Fy (= Fsin α: α is an inclination angle of the engaging surface 55c) of the urging force F acting. The other configuration is the same as that of the first embodiment.

  Thus, according to the present embodiment, as shown in FIGS. 11 and 12, the toner container 12b is temporarily placed at a position higher than the mounting position by the cam surface 55a formed on the upper surface of the cam member 55A of the entrance shutter 55. Since the convex coupling 60 (see FIG. 11) of the toner container 12b does not match the concave coupling 102 (FIG. 12) on the apparatus main body 100 side, the claws of the couplings 60 and 102 are The occurrence of defects such as damage is prevented. Similarly, the other toner containers 12a, 12c, and 12d are temporarily held at a position higher than the mounting position by the cam surface 55a of the entrance shutter 55.

  Further, according to the present embodiment, the biasing force F acting on the toner container 12b via the engagement surface 55c of the entrance shutter 55 of the intermediate transfer unit 50 when the toner container 12b is mounted as shown in FIG. Since the toner container 12b is configured to be pressed in the mounting direction by the vertical component force Fy, the toner container 12b is securely mounted and prevented from falling off. When the other toner containers 12a, 12c, and 12d are also mounted, they are similarly pressed in the mounting direction (downward) by the vertical component force Fy of the urging force F of the tension spring 59, so that the mounting is ensured. Falling off is prevented.

  In addition, in the present embodiment, as in the first embodiment, it is possible to reliably prevent the toner from being scattered when the toner containers 12a to 12d are attached and detached.

1 is a front sectional view of a color image forming apparatus according to the present invention. FIG. 2 is a perspective view of an intermediate transfer unit according to Embodiment 1 of the present invention. FIG. 3 is a perspective view showing a relationship between an intermediate transfer unit, a toner container, and a developing device according to Embodiment 1 of the present invention. FIG. 3 is a partial cross-sectional perspective view illustrating a state in which toner is supplied from a toner container to a developing device through an intermediate transfer unit according to Embodiment 1 of the present invention. FIG. 3 is a partial cross-sectional view illustrating delivery of toner from a toner container to an intermediate transfer unit according to Embodiment 1 of the present invention. FIG. 3 is a partial perspective view of an entrance shutter portion of the intermediate transfer unit according to Embodiment 1 of the present invention. 1 is a partial perspective view of a developing device of a color image forming apparatus according to the present invention. (a) is a partial bottom view showing a toner inlet open state of the intermediate transfer unit according to Embodiment 1 of the present invention, and (b) is a partial bottom view showing a toner inlet closed state of the intermediate transfer unit. FIG. 4 is a partial perspective view illustrating a relationship between an exit shutter of the intermediate transfer unit according to Embodiment 1 of the present invention and a developing device. It is a perspective view of the exit shutter of the intermediate transfer unit according to the first embodiment of the present invention. FIG. 10 is a partial perspective view illustrating a state where a toner container is temporarily held on an entrance shutter of an intermediate transfer unit according to a second embodiment of the present invention. FIG. 10 is a partial perspective view illustrating a state where a toner container is temporarily held on an entrance shutter of an intermediate transfer unit according to a second embodiment of the present invention. FIG. 6 is a partial perspective view illustrating a state where a toner container is mounted on an intermediate transfer unit according to Embodiment 2 of the present invention. FIG. 10 is a partial explanatory diagram illustrating a force that acts on the toner container from the exit shutter when the toner container is attached to the intermediate transfer unit according to the second embodiment of the present invention.

Explanation of symbols

1M Magenta image forming unit 1C Cyan image forming unit 1Y Yellow image forming unit 1BK Black image forming unit 2a to 2d Photosensitive drum (photoconductor)
3a to 3d charger 4a to 4d developing device 5a to 5d transfer roller 6a to 6d drum cleaning device 7 intermediate transfer belt 8 secondary transfer counter roller 9 tension roller 10 secondary transfer roller 11 belt cleaning device 12a to 12d toner container 13 laser Scanner unit (LSU)
DESCRIPTION OF SYMBOLS 14 Paper feed cassette 15 Pickup roller 16 Feed roller 17 Retard roller 18 Conveyance roller pair 19 Registration roller pair 20 Conveyance roller pair 21 Paper discharge tray 22 Fixing device 23 Paper discharge roller pair 24 Paper discharge device 50 Intermediate transfer unit 50a-50d Intermediate transfer Unit mounting portion 51 Toner inlet 52 Toner outlet 53 Toner transport path 54 Toner transport screw 55 Inlet shutter 55A Inlet shutter cam member 55B Inlet shutter seal material 55a Cam member cam surface 55b Seal material toner inlet 56 Tension spring ( Energizing means)
57 Toner supply port of developing device 58 Exit shutter 58a Seal portion of exit shutter 59 Tension spring (biasing means)
60 Coupling of toner container 100 Image forming apparatus main body 100A Main body frame 100a Top cover 101 Guide groove of main body frame 102 Coupling on main body side

Claims (5)

A plurality of detachable toner containers arranged in parallel in the main body of the color image forming apparatus, a plurality of image carriers arranged in parallel below and a middle of the developing device, and a plurality of image carriers. A unit comprising a travelable endless intermediate transfer belt on which toner images of respective colors formed on a body are sequentially primary transferred, and a secondary transfer of the toner image primarily transferred onto the intermediate transfer belt onto a sheet A plurality of toner inlets for receiving toner from the toner containers are formed on the upper surface of the housing, and toner outlets for discharging the toner received from the toner inlets to the developing devices are provided on the lower surface of the housing. And an intermediate transfer unit in which a toner transport path connecting the toner inlet and the toner outlet is formed in the housing .
An intermediate transfer unit comprising an entrance shutter that opens and closes each toner inlet in conjunction with the attaching and detaching operation of each toner container.
  2. The intermediate transfer unit according to claim 1, wherein an upper surface of the entrance shutter is a slope, and the toner container can be temporarily held on the slope at a position higher than a mounting position.   The entrance shutter is urged to the closing side by an urging means, and the engagement surface of the entrance shutter with the toner container is a slope, and when the toner container is mounted, the entrance shutter passes through the engagement surface of the entrance shutter. 3. The intermediate transfer unit according to claim 1, wherein the toner container is pressed in the mounting direction by a component force of an urging force acting on the toner container.   The intermediate transfer unit according to claim 1, further comprising an exit shutter that simultaneously opens and closes all the toner outlets in conjunction with the attaching and detaching operation of the toner container.   A color image forming apparatus comprising the intermediate transfer unit according to claim 1.

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