JP2007121958A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus capable of preventing toner from being aggregated near the inner wall of a toner carrying pipe, thereby suppressing the deterioration of developing quality due to the toner aggregation. <P>SOLUTION: The image forming apparatus includes: an image forming part for forming a toner image and also transferring the toner image to a paper; a fixing unit for fixing the toner image transferred to the paper in the image forming part; a paper carrying part for carrying the paper to the image forming part and the fixing unit; and a toner supply part for supplying the toner to the image forming part. The toner supply part includes: a toner supply pipe 25 for supplying the toner to the image forming part; a toner storage part 5 for storing the toner therein; the toner carrying pipe 26 for carrying the toner stored in the toner storage part 5 to the toner supply pipe 25; and a toner aggregation preventing mechanism of preventing the aggregation of the toner near the inner wall of the toner carrying pipe 26. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly, to a full-color image forming apparatus that supplies toner from the outside.

  In an electrophotographic image forming apparatus, a charger, an exposure device, a developing device, a transfer device, a cleaning device, and the like are provided around a photosensitive drum as an image carrier. A fixing device is provided on the downstream side of the photosensitive drum in the transport direction of the transfer material. In such an image forming apparatus, first, the surface of the photosensitive drum is uniformly charged by the charger. Thereafter, based on the image information, the photosensitive drum is exposed by the exposure device, and an electrostatic latent image is formed on the surface of the photosensitive drum. This electrostatic latent image is developed by a developing device. Here, in the case of a full-color image forming apparatus, there are provided four development units each containing a cyan developer, a magenta developer, a yellow developer, and a black developer, and four colors of cyan, magenta, yellow, and black, respectively. The toner image is developed. Thereafter, the developed toner image is transferred onto a transfer material by a transfer device, further fixed by a fixing device, and discharged to a discharge portion. Residual developer remaining on the photosensitive drum is cleaned by a cleaning unit.

In such an image forming process, the toner contained in the developing unit is consumed with the development, and therefore it is necessary to supply the toner. As a method for supplying toner consumed in image formation, there is a method in which a toner container is provided outside the developing unit and toner is supplied from the outside (Japanese Patent Laid-Open No. 10-198149). In the developing device described in Japanese Patent Laid-Open No. 10-198149, the toner is supplied by entering the toner supplying device into the developing device for each color to which toner is to be supplied. In the developing device described in this publication, toner is supplied from the outside by a toner supply device having a toner conveying member therein.
JP 10-1981149 A

  In the conventional image forming apparatus, since toner near the inner wall of the toner transport pipe is difficult to be transported, the toner may aggregate and adhere to the inner wall of the toner transport pipe. In such a case, toner agglomerates adhering to the inner wall of the toner supply pipe may be peeled off, and the agglomerates may be sent to the developing device as they are to cause development quality deterioration.

  An object of the present invention is to prevent the toner from aggregating in the vicinity of the inner wall of the toner transport pipe, and to suppress the development quality deterioration due to the toner agglomerates.

  An image forming apparatus according to a first aspect of the present invention includes an image forming unit that forms a toner image and transfers the formed toner image onto a sheet, a fixing unit that fixes the toner image transferred onto the sheet by the image forming unit, and an image A paper transport unit that transports the paper to the forming unit and the fixing unit, and a toner supply unit that supplies toner to the image forming unit are provided. The toner supply unit includes a toner supply member that supplies toner to the image forming unit, a toner storage unit that stores toner therein, a toner transfer pipe that transfers toner in the toner storage unit to the toner supply unit, and a toner transfer pipe A toner aggregation preventing mechanism for preventing toner aggregation near the inner wall.

  In this image forming apparatus, when toner is supplied, the toner in the toner container is transported to the toner supply member by the toner transport pipe. The toner conveyed to the toner supply member is supplied to the image forming unit via the toner supply member.

  Here, since toner aggregation is prevented by the toner aggregation prevention mechanism, it is possible to prevent deterioration in development quality due to the aggregate.

  An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the toner supply member supplies toner to a toner supply position that is located when supplying the toner to the image forming unit and to the image forming unit. The toner transport pipe moves in correspondence with the movement of the toner supply member between the toner supply position and the retracted position.

  An image forming apparatus according to a third aspect is the image forming apparatus according to the second aspect, wherein the toner aggregation preventing mechanism prevents toner aggregation by deformation of the toner transport pipe as the toner supply member moves. To do.

  In the image forming apparatus, the toner transport pipe is deformed when the toner supply member moves between the toner supply position and the retracted position.

  Here, since the inner wall of the toner transport pipe and the toner in the vicinity thereof move relatively with the deformation of the toner transport pipe, toner aggregation can be prevented. For this reason, it is possible to prevent development quality deterioration due to toner aggregates from being suppressed.

  An image forming apparatus according to a fourth aspect is the image forming apparatus according to the second or third aspect, wherein the toner aggregation preventing mechanism includes a toner conveying pipe that moves in response to the movement of the toner supply member, and a toner conveying pipe. And a toner conveying member provided inside.

  In this image forming apparatus, the toner transport pipe moves as the toner supply member moves. Then, by repeatedly moving the toner transport pipe and stopping to the supply position and the retracted position, the inner wall of the toner transport pipe may vibrate or the toner transport pipe and the internal toner transport member may collide. is there. Due to the vibration and collision caused by such movement and stop of the toner conveying pipe, the toner is agitated and hardly aggregates.

  An image forming apparatus according to a fifth aspect is the image forming apparatus according to any one of the second to fourth aspects, wherein the toner conveying member is a toner conveying screw or a coil spring.

  The image forming apparatus according to claim 6 is the image forming apparatus according to any one of claims 2 to 5, wherein the toner transport pipe is provided between the toner supply position and the retracted position of the toner supply member. Expands and contracts as it moves.

  Here, since the toner in the vicinity of the toner transport pipe is agitated as the toner transport pipe expands and contracts, toner aggregation can be prevented. For this reason, it is possible to prevent development quality deterioration due to toner aggregates from being suppressed.

  In the present invention, since the toner is agitated inside the toner conveying pipe, it is possible to prevent the toner from aggregating and to prevent the deterioration of the development quality due to the aggregate.

  FIG. 1 shows a color printer 1 as a color image forming apparatus according to an embodiment of the present invention. FIG. 1 is a schematic diagram for showing the arrangement of each component, and details of each part are omitted.

[overall structure]
The color printer 1 is connected to a computer (not shown) or the like, and is a device that can print a color image on paper based on image information sent from the computer or the like. In the color printer 1, the right side in FIG. 1 is the side operated by the operator, and in the following, the right side of the apparatus in FIG. 1 is the front side and the left side is the back side.

  The color printer 1 includes a photosensitive drum 2, a rotary developing device 3, a laser unit 4, a toner storage unit 5, a plurality of toner supply devices 6, an intermediate transfer belt 7, a secondary transfer roller 8, a fixing unit. And a device 9.

[Photosensitive drum]
The photosensitive drum 2 has an electrostatic latent image formed on the surface thereof, and is rotatably provided in the center of the apparatus. The rotation axis of the photosensitive drum 2 extends in the lateral direction as viewed from the front side of the apparatus. It is provided so as to extend perpendicular to the paper surface of FIG. A charging roller 10 for uniformly charging the surface of the photosensitive drum 2 is provided above the photosensitive drum 2. Further, a drum cleaning device 11 for cleaning the toner and adhering matter remaining on the surface of the photosensitive drum 2 is provided on the side of the photosensitive drum 2.

[Rotating development device]
The rotary developing device 3 develops the electrostatic latent image formed on the photosensitive drum 2 with toner of each color, and is adjacent to the photosensitive drum 2 and has a center substantially the same as the center of the photosensitive drum 2. It is provided so that it may become a position. The rotary developing device 3 includes a rotary frame 15 and four developing units 16 provided corresponding to the four color toners and supported by the rotary frame 15. The rotating frame 15 has a cylindrical shape that is rotatable around an axis parallel to the rotating shaft of the photosensitive drum 2 and is rotated by a driving mechanism including a motor and a gear (not shown). The rotating frame 15 has four sections divided into four equal in the circumferential direction by a partition frame extending radially from the center of the rotating shaft, and each section has four toners of yellow, cyan, magenta, and black. A developing device 16 corresponding to the color is arranged.

  Each developing device 16 has substantially the same configuration, and is provided with a developing roller that can be disposed to face the photosensitive drum 2, a stirring roller for stirring the toner, and the like. In addition, a toner supply unit is provided on the outer peripheral side of the case of the developing unit 16 in order to supply toner from the toner storage unit to the inside of the developing unit 16. The toner supply unit is formed by forming an opening in a part of the case and fixing an elastic member having a slit formed in the opening.

[Laser unit]
The laser unit 4 scans and exposes the photosensitive drum 2 based on image information sent from an external computer or the like. The laser unit 4 is provided above the photosensitive drum 2 and from the rotary shaft of the rotary developing device 3. It is arranged on the back side. Precisely, the front end of the laser unit 4 (the end on the side from which the laser beam is emitted) is located almost directly above the rotation axis of the rotary developing device 3, and is inclined downward as it goes to the rear end side. The end is located below the upper end of the rotary developing device 3. The internal configuration of the laser unit 4 is the same as the conventional configuration, and includes a laser light source, a polygon mirror, a polygon mirror driving motor, and the like. In addition, a reflection mirror 20 is provided in front of the laser light path of the laser unit 4. Therefore, as indicated by a one-dot chain line in FIG. 1, the laser light emitted from the laser unit 4 is bent by the reflection mirror 20 and passes above the front side of the rotary developing device 3, and the surface of the photosensitive drum 2. It comes to be irradiated.

[Toner container]
The toner accommodating portion 5 is a portion that accommodates toner to be supplied to each developing device 16 of the rotary developing device 3, and is located above the photosensitive drum 2 and on the side facing the laser unit 4 (on the front side of the device). Has been placed. The toner storage unit 5 includes four storage units that store toner of each color of yellow, cyan, magenta, and black, which are arranged side by side in the horizontal direction (the vertical direction in FIG. 1). Further, the toner storage portion 5 can be taken out to the front side of the apparatus.

[Toner supply device]
Each of the plurality of toner supply devices 6 is for supplying the toner of each color stored in the toner storage unit 5 to the corresponding developing device 16. Above the photosensitive drum 2, the laser unit 4 and the toner are supplied. It arrange | positions in the space between the accommodating parts 5. FIG. As shown in FIG. 2, each toner supply device 6 connects a toner supply pipe 25 that can move in the vertical direction and a toner supply pipe 25 corresponding to a portion of the toner storage portion 5 that stores toner of each color. And a driving mechanism 27 for moving the toner supply pipe 25 up and down.

  Since the four toner supply pipes 25 have the same configuration, only one toner supply pipe 25 will be described below.

  The toner supply pipe 25 is for supplying toner to the developing device 16 and is long in the vertical direction, and has an upper end inclined toward the front side of the apparatus and a lower end inclined toward the rear side of the apparatus. Further, the tip of the toner supply pipe 25 has a tapered shape, and when the toner supply pipe 25 moves downward, the toner supply port formed at the tip passes through the slit formed in the toner supply portion of the developing device 16. Can enter the interior. Further, a first toner conveying screw 30 is disposed inside the toner supply pipe 25.

  As shown in FIG. 2, the first toner transport screw 30 is a member for transporting toner to the toner supply port, and is formed in a spiral shape on the outer periphery of the rotary shaft that is long in the vertical direction. It is a screw-shaped member which consists of a conveyance piece.

  As shown in FIGS. 2 and 4, the toner transport pipe 26 includes a first connection portion 26 a with the toner storage portion 5, a second connection portion 26 b with the toner supply pipe 25, a first connection portion 26 a, and a second connection portion. And an elastic member 28 disposed between the connecting portions 26b. The first connection portion 26 a is a portion for connecting the toner storage portion 5 and the toner transport pipe 26, and is a portion formed in a cylindrical shape continuously formed from the toner storage portion 5. The second connection portion 26 b is a portion for connecting the toner supply pipe 25 and the toner transport pipe 26, and is a portion formed in a cylindrical shape continuously formed on the toner supply pipe 25. The elastic member 28 is a member for allowing the toner supply pipe 25 to move following the vertical movement of the toner supply pipe 25, and is a cylindrical member that covers the first connection portion 16a and the second connection portion 26b. A second toner conveying screw 31 is disposed inside. The second toner conveying screw 31 is a screw-like member composed of a rotating shaft 31a extending in the left-right direction and a conveying piece 31b formed in a spiral shape on the outer periphery of the rotating shaft 31a. It is made of a material having low rigidity such as silicon. Further, the second toner conveying screw 31 is connected to a motor (not shown) at an end portion on the toner accommodating portion 5 side, and an end portion on the toner supply pipe 25 side is a free end. A rotation shaft 31 a of the second toner conveying screw 31 extends from the toner storage unit 5 to the toner supply pipe 25. When the toner supply pipe 25 moves from the retracted position to the toner supply position, the toner transport pipe 26 is deformed. Accompanying the deformation of the toner transport pipe 26, the inner wall of the toner transport pipe 26 and the toner in the vicinity thereof move relative to each other, so that toner aggregation near the inner wall of the toner transport pipe 26 can be prevented. As the toner supply pipe 25 moves, the inner wall of the toner transport pipe 26 may collide with the second toner transport screw 32 as shown in FIG. Such a collision between the inner wall of the toner conveying pipe 26 and the second toner conveying screw 32 and the movement of the toner conveying pipe 26 cause the toner conveying pipe 26 to vibrate. Further, when the toner supply pipe 25 moves from the retracted position to the toner supply position, the elastic portion of the toner transport pipe 26 is pressed and slightly contracts in the left-right direction. For this reason, the length of the toner transport pipe 26 is shorter when the toner supply pipe 25 is at the toner supply position than when the toner supply pipe 25 is at the retracted position. Further, at this time, the end of the second toner conveying screw 31 on the toner supply pipe 25 side moves further to the toner supply pipe 25 side when the toner supply pipe 25 is at the toner supply position than when the toner supply pipe 25 is at the retracted position. is doing. Accordingly, when the toner supply pipe 25 is moved from the retracted position to the toner supply position, the toner transfer pipe 26 and the second toner transfer screw 31 are relatively moved to stir the interior of the toner transfer pipe 26 (toner Anti-aggregation mechanism). For this reason, aggregation of the toner in the toner transport pipe can be prevented. On the other hand, when the toner is supplied, the toner in the toner container 5 is transported to the toner supply pipe 25 side through the transport pipe 26. The toner transported to the toner supply pipe 25 side is transported to the toner supply port by the first toner transport screw 30 disposed in the toner supply pipe.

  The drive mechanism 27 includes a rack 32 provided along the axial direction on the outer periphery of the toner supply pipe 25, and a pinion gear 33 that meshes with the rack 32. The pinion gear 33 is rotatably supported by the frame of the apparatus and is driven by a motor 33a, a worm, a worm wheel, and a reduction gear train as shown in FIG. Then, the drive mechanism 27 causes the four toner supply pipes 25 to have an upper retracted position (a position indicated by a solid line in FIG. 1) and a supply position (the lower end in FIG. Position indicated by a two-dot chain line).

[Intermediate transfer belt]
The intermediate transfer belt 7 is one to which the toner images of the respective colors formed on the photosensitive drum 2 are sequentially transferred, and is disposed below the photosensitive drum 2 and the toner storage portion 5. The intermediate transfer belt 7 is stretched between a driving roller 35 and a driven roller 36 urged away from the driving roller 35 by a spring 38. Further, the portion of the transfer belt 7 facing the photosensitive drum 2 is configured to abut against the photosensitive drum 2 by a pair of primary transfer rollers 37a and 37b.

  A belt cleaning device 40 for cleaning the transfer belt 7 is provided on the back side of the driving roller 35 and below the rotary developing device 3. The belt cleaning device 40 is provided at a position facing the driving roller 35 and is in contact with the surface of the transfer belt 7, and a cleaning roller 42 disposed above the fur brush 41 so as to contact the fur brush 41. And a blade 43 disposed so that the tip thereof is in contact with the surface of the cleaning roller 42, and a collection spiral 44 disposed side by side below the blade 43.

  In the cleaning device 40, the deposit on the intermediate transfer belt 7 is scraped off by the fur brush 41, and the deposit scraped off by the fur brush 41 is collected by the cleaning roller 42. Then, the deposit collected on the cleaning roller 42 side is scraped off from the surface of the cleaning roller 42 by the blade 43 and is collected by a collecting spiral 44 to a collecting unit (not shown).

[Secondary transfer roller]
The secondary transfer roller 8 is for transferring the image transferred to the intermediate transfer belt 7 onto the conveyed paper, and is disposed below the drive roller 35 so as to face the drive roller 35. . A bias voltage for image transfer is applied to the secondary transfer roller 8 with respect to the sheet by a voltage applying unit (not shown).

[Fixing device]
The fixing device 9 is for fusing and fixing the toner transferred onto the paper, and is disposed below the rotary developing device 3 and on the back side of the device. The fixing device 9 includes a heating roller 9a having a built-in heater and a pressure roller 9b in pressure contact with the heating roller 9a.

[Discharge part]
In the printer 1, a discharge unit 50 is formed on the upper surface of the apparatus, that is, above the laser unit 4, the toner supply device 6, and the toner storage unit 5. The discharge unit 50 is lowest on the laser unit 4 side (the rear side of the apparatus), and gradually increases as it goes to the toner storage unit 5 side (the front side of the apparatus), and the toner storage unit connected to the curved surface part. 5 and a flat portion located above 5.

[Transport section]
Between the paper feed unit 51 and the discharge unit 50, a transport unit that transports paper is provided. The conveyance unit reaches the first conveyance path 55 from the paper supply unit 51 to the secondary transfer roller 8, the second conveyance path 56 from the secondary transfer roller 8 to the fixing device 9, and the fixing device 9 to the discharge unit 50. And a third conveyance path 57. A branch claw 58 is provided at the outlet of the fixing device 9. A return conveyance path for returning the sheet to the first conveyance path 55 is provided between the branch claw 58 and the first conveyance path 55. 59 is provided.

  The first conveyance path 55 includes a curved path 55a for reversing the conveyance direction while conveying the sheet fed from the paper feed cassette 52 upward, and a straight path 55b extending from the curved path 55a to the secondary transfer roller 8. And have. These conveyance paths are formed by a pair of guide plates and rollers that convey the sheet while guiding the sheet, and a sensor for detecting the sheet is provided at a predetermined position. In addition, a registration roller pair 60 for controlling the sheet conveyance timing is disposed on the straight path 55b.

  The second conveyance path 56 is formed substantially linearly, and includes a guide plate and a pair of rollers that convey the sheet while guiding the sheet. In addition, a sensor for detecting a sheet is provided at a predetermined position on the conveyance path.

  The third conveyance path 57 has a vertical conveyance path formed on the downstream side of the branch claw 58 in the conveyance direction. That is, after passing through the branching claw 58, the sheet is conveyed substantially vertically upward and discharged to the discharge unit 50. The third transport path 57 is also composed of a guide plate and a pair of rollers that transport the paper while guiding it, as described above.

  The return conveyance path 59 branches downward from the third conveyance path 57 at the portion where the branch claw 58 is provided, and passes below the fixing device 9, the second conveyance path 56, the secondary transfer roller 8, and the registration roller pair 60. Further, this is a further upward conveying path, and joins the upstream side of the first conveying path 55 in the conveying direction of the registration roller pair 60. That is, the return conveyance path 59 is provided between the straight path 55b of the first conveyance path 55 and the second conveyance path 56 and the sheet feeding cassette 52 in the up-down direction, and allows the sheet that has passed through the fixing device 9 to be secondary This is a conveyance path for returning the registration roller pair 60 disposed on the upstream side of the transfer roller 8 to the further upstream side. Similarly to the above, the return conveyance path 59 is also composed of a guide plate and a roller pair for conveying the sheet while guiding the sheet, and a sheet detection sensor is provided at a predetermined position.

[Paper Tray]
A paper feed tray 65 is disposed below the toner container 5 and above the paper feed cassette 52 so as to form a side wall on the front side of the apparatus. The lower end of the paper feed tray 65 is supported so as to be freely rotatable (openable and closable) in the vicinity of the curved path 55a of the first conveying path 55, and the upper end of the sheet feed tray 65 is tilted toward the front of the apparatus with the pivot fulcrum 65a as a center. It is possible. When the paper feed tray 65 is opened in this way, paper can be placed on the paper feed tray 65 and fed to the curved path 55 a of the first transport path 55.

[Image forming operation]
Next, the image forming operation will be briefly described. First, when the color printer is turned on, various parameters are initialized, and initial settings such as setting the temperature of the fixing unit are executed. When image data is input from a computer or the like connected to the printer and an instruction to start printing is given, an image forming operation is executed as follows. During the image forming operation, the toner supply pipe 25 is moved to the upper retracted position. Therefore, the laser beam path is not blocked by the toner supply pipe 25.

  First, the photosensitive drum 2 is charged by the charging roller 10. Thereafter, scanning exposure corresponding to the image data is performed on the photosensitive drum 2 by the laser unit 4, and an electrostatic latent image is formed on the photosensitive drum 2. Next, the rotary developing device 3 is rotated so that the corresponding color developing device 16 is opposed to the photosensitive drum 2. In this state, the electrostatic latent image on the photosensitive drum 2 is developed with the corresponding color toner. The developed image is transferred to the intermediate transfer belt 7. A full color image is formed on the intermediate transfer belt 7 by sequentially repeating the above operation for each color. The residual toner remaining on the photosensitive drum 2 is cleaned by the drum cleaning device 11 and discarded in a waste toner container (not shown).

  On the other hand, in the paper feed unit 51, one sheet of paper is taken out from the paper feed cassette 52 by the forward feed roller 53 and the double feed prevention mechanism 54 and is transported to the registration roller pair 60 through the first transport path 55. Thereafter, the sheet is conveyed from the registration roller pair 60 in time with image formation on the intermediate transfer belt 7 and guided to the secondary transfer roller 8. The secondary transfer roller 8 is in contact with the intermediate transfer belt 7, and the full color image formed on the intermediate transfer belt 7 is transferred onto the sheet by the transfer bias applied to the secondary transfer roller 8. The sheet is guided to the fixing device 9 through the second conveyance path 56, and the image is fixed on the sheet by heating and pressing by the fixing device 9. In the case of single-sided printing, the paper is guided to the third conveyance path 57 via the branching claw 58 and discharged to the discharge unit 50.

  In the case of duplex printing, the sheet that has passed through the fixing device 9 is guided to the return conveyance path 59 side by the branching claw 58 and returned to the first conveyance path 55 again. The sheet returned to the first conveyance path 55 is temporarily stopped by the registration roller pair 60. Then, after the image on the back side is formed on the intermediate transfer belt 7 by the same operation as described above, the sheet waiting on the registration roller pair 60 is sent to the secondary transfer roller 8 side in time. Thereafter, the same operation as described above is executed, guided to the third conveyance path 57 side through the branching claw 58, and discharged to the discharge unit 50.

[Operation when supplying toner]
At the time of supplying the toner, the toner is supplied from the toner container 5 to the toner transport pipe 26, and the toner supplied to the toner transport pipe 26 is transported to the toner supply pipe 25 by the second toner transport screw 31. The toner conveyed to the toner supply pipe 25 is conveyed to the toner supply port of the toner supply pipe 25 by the first toner conveyance screw 30 in the toner supply pipe 25 and supplies the toner into the developing device 16. At this time, the toner supply pipe 25 moves to the toner supply position, and this movement moves and stops the portion of the toner transport pipe 26 near the toner supply pipe 25 side. By repeating this movement and stop, the inner wall of the toner transport pipe 26 may vibrate, or the toner transport pipe 26 and the internal second toner transport screw 31 may collide (toner aggregation preventing mechanism). Due to the vibration and collision caused by such movement and stop of the toner conveying pipe 26, the toner is agitated and hardly aggregates.

[Other Embodiments]
In the above-described embodiment, the inner wall of the toner transport pipe 26 is vibrated by moving and stopping the toner transport pipe 26 or colliding with the toner transport screw 30, and the toner near the inner peripheral wall of the toner transport pipe 26 is agitated. Although aggregation is prevented, the present invention is not limited to this. As shown in FIG. 5, the toner conveying pipe 26 is provided with a portion 26 c on the bellows that can be expanded and contracted. By expanding and contracting, the inner peripheral wall of the toner transport pipe 26 may be moved to stir the toner to prevent toner aggregation.

1 is a schematic configuration diagram of a color printer according to an embodiment of the present invention. 2 is a detailed cross-sectional configuration diagram of a toner supply device. FIG. 3 is an external view of a driving mechanism of the toner supply pipe 25. FIG. 4 is a cross-sectional view of the toner transport pipe 26. The figure of the toner conveyance pipe 26 of other embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 2 Photosensitive drum 3 Rotating developing device 4 Laser unit 5 Toner accommodating part 6 Toner supply device 7 Intermediate transfer belt 8 Secondary transfer roller 9 Fixing device 16 Developer 25 Toner supply pipe 26 Toner conveyance pipe 30 First toner conveyance Screw 31 Second toner conveying screw

Claims (6)

An image forming unit that forms a toner image and transfers the formed toner image to paper;
A fixing unit for fixing the toner image transferred to the paper in the image forming unit;
A paper transport unit for transporting paper to the image forming unit and the fixing unit;
A toner supply unit for supplying toner to the image forming unit,
The toner supply unit includes a toner supply member that supplies toner to the image forming unit, a toner storage unit that stores toner therein, a toner transport pipe that transports toner in the toner storage unit to the toner supply unit, A toner aggregation preventing mechanism for preventing toner aggregation near the inner wall of the toner conveying pipe;
Image forming apparatus. The toner supply member moves between a toner supply position positioned when supplying toner to the image forming unit and a retracted position positioned when toner is not supplied to the image forming unit;
The toner transport pipe moves in response to the movement of the toner supply member between the toner supply position and the retracted position of the toner supply member;
The image forming apparatus according to claim 1.   3. The image forming apparatus according to claim 1, wherein the toner aggregation preventing mechanism prevents toner aggregation by deforming the toner transport pipe as the toner supply member moves. The toner aggregation preventing mechanism includes the toner transport pipe that moves in response to the movement of the toner supply member, and a toner transport member provided in the toner transport pipe.
The image forming apparatus according to claim 2. The toner conveying member is a toner conveying screw or a coil spring;
The image forming apparatus according to claim 2.   The image forming apparatus according to claim 2, wherein the toner transport pipe expands and contracts as the toner supply member moves between the toner supply position and the retracted position of the toner supply member. .

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