JP2006208990A - Development unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To miniaturize a development unit by supplying toner from the outside for simplifying a mechanism of a joint between a rotary and a toner supply mechanism. <P>SOLUTION: The development unit has a rotary developing device 3, a toner supply device 6, a drive mechanism 27 and a shutter mechanism. The rotary developing device 3 incorporates a developing roller, the toner supply device 6 supplies the toner to a rotary developing body 3 and has an inner cylinder part 251 having an inside opening 251a at the tip part and an outer cylinder part 252 provided to be freely and relatively rotated with the inner cylinder part at outer circumference of the inner cylinder part and having an outside opening 252a on the side of the tip part. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing unit, and more particularly to a developing unit of a type in which toner is supplied from the outside.

  In order to facilitate maintenance, the developing unit of the image forming apparatus is filled with a certain amount of toner in the developing unit, and is replaced when the toner is used up. However, the developing unit cannot be replaced frequently from an economic point of view, and the toner volume must be increased in order to form an image to some extent. Therefore, downsizing is difficult.

Therefore, in order to reduce the size of the developing unit, a developing unit that supplies toner from the outside has been proposed. As a developing unit that supplies toner from the outside, there is one described in Japanese Patent Laid-Open No. 2001-134045. Japanese Patent Laid-Open No. 2001-134045 discloses an image forming apparatus employing a rotary developing system, in which a shutter mechanism opens while a joint portion of a rotary developing unit that rotates with a toner supply device slides. It is configured to be connected to the developing device at the stop position. In this image forming apparatus, since a mechanism for supplying toner from the outside to the developing device is complicated, the rotary frame and the developing device are integrally configured.
JP 2001-134045 A

  In a conventional developing unit that supplies toner from the outside of the developing unit, the rotary part of the rotary and the toner supply part on the main body side must be jointed, and the hose joint is fixed to the rotary while sliding. The structure for supplying the toner to the developing device is complicated. Furthermore, since a sliding mechanism for the joint portion must be provided outside the rotary, the size cannot be reduced beyond a certain level. Further, regarding the replacement of the developing device, it is difficult to replace each color one by one because the joints of the rotary and the toner supply mechanism are complicatedly configured. In addition, it is necessary to prevent the toner from leaking between the developing unit and the rotary when changing the toner one by one. However, no measures are taken to prevent the toner from leaking. It is difficult to change one color at a time.

  An object of the present invention is to reduce the size of the developing unit by supplying toner from the outside, and to simplify the joint mechanism of the rotary and the toner supply mechanism.

  Another object of the present invention is to prevent toner from leaking when toner is replaced, and to facilitate toner replacement.

  A developing unit according to a first aspect includes a container main body, a toner supply device, a driving device, and a shutter mechanism. The container main body has a developing roller inside, and the toner supply device is for supplying toner to the container main body, and has an inner cylinder having an inner opening at the tip, and an inner cylinder at the outer periphery of the inner cylinder. An outer cylinder is provided that is relatively rotatable and has an outer opening on the side surface of the tip. The drive device allows the tip of the toner supply device to enter the container main body and separate from the container main body. The shutter mechanism is configured to align at least a part of the inner opening of the inner cylinder and the outer opening of the outer cylinder when the tip of the toner supply device enters the container body, and when the tip is positioned outside the container body. This is for positioning the inner opening and the outer opening at different positions.

  In this developing unit, when supplying toner, the tip of the toner supply device is caused to enter the container main body by the driving device, and at least a part of the inner opening of the inner cylinder and the outer opening of the outer cylinder coincide with each other. Internal toner is supplied to the container body. When the toner supply is completed, the tip of the toner supply device that has entered the container main body is separated from the container main body by the driving device. At this time, when the front end portion of the toner supply device is positioned outside the container body by the shutter mechanism, the inner opening and the outer opening are shifted from each other, so that the toner inside does not come out and the toner supply No toner leaks from the device.

  Here, by supplying the toner from the outside, the development unit can be reduced in size, and the structure of the joint mechanism between the rotary developing device and the toner supply mechanism is simplified, and the toner leaks when the toner is replaced. It can suppress getting dirty.

  A developing unit according to a second aspect is the developing unit according to the first aspect, wherein the toner supply device has a toner conveying screw rotatably disposed inside the inner cylinder portion.

  In this developing unit, the toner is conveyed into the container body by the toner conveying screw.

  A developing unit according to a third aspect is the developing unit according to the first or second aspect, wherein the outer opening of the outer cylinder is larger than the inner opening of the inner cylinder portion.

  Here, when the outer cylinder rotates relative to the inner cylinder, the toner can be supplied into the container body even if an error occurs in some rotation angle. In addition, for example, if the gap between the inner cylinder and the outer cylinder is reduced, toner can be prevented from entering the gap between the inner cylinder and the outer cylinder, and the toner can be prevented from being scattered and contaminating the inside of the machine during toner replacement. be able to.

  A developing unit according to a fourth aspect is the developing unit according to any one of the first to third aspects, and includes a shutter mechanism that rotates the outer cylinder in accordance with the driving of the toner supply device driven by the driving device.

  Here, for example, if the gap between the inner cylinder and the outer cylinder is narrowed, the toner can be prevented from entering the gap between the inner cylinder and the outer cylinder, and the toner can be scattered when the toner is replaced. Can be suppressed.

  A developing unit according to a fifth aspect is the developing unit according to the fourth aspect, wherein the shutter mechanism is disposed on the outer peripheral surface of the outer cylinder and on the outer peripheral part of the outer cylinder, and the guide part is inserted. And a spiral guide groove.

  Here, the guide portion provided on the outer peripheral surface of the outer cylinder moves along a spiral guide groove that is disposed on the outer peripheral portion of the outer cylinder and is inserted into the guide portion, and the outer cylinder is moved along with the movement of the guide portion. Rotates.

  A developing unit according to claim 6 is the developing unit according to claim 4, and has a rack provided on the outer peripheral surface of the outer cylinder, and a pinion disposed on the outer peripheral part of the outer cylinder and engaging with the rack. is doing.

  Here, the tip of the toner supply device can be moved up and down by rotating the pinion.

  A developing unit according to a seventh aspect is the developing unit according to any one of the first to sixth aspects, wherein the speed at the time when the tip of the toner supply device enters or separates from the container main body is high. The speed is 2 mm to 20 mm per second.

  Here, it is possible to move the toner supply device even with a low torque brush motor, and it is possible to secure a force for expanding the entry portion when the tip portion of the toner supply device enters the container body.

  A developing unit according to an eighth aspect is the developing unit according to any one of the first to seventh aspects, wherein a limit switch for detecting a limit position of movement in at least one of the upward and downward directions of the toner supply device is provided. I have.

  In this case, the limit switch can detect the movement limit position in at least one of the upward and downward directions of the toner supply device. Further, the movement of the toner supply device can be restricted above or below the limit position.

  A developing unit according to a ninth aspect is the developing unit according to any one of the first to eighth aspects, wherein the toner supply device enters the container main body at a joint portion with the tip of the toner supply device on the container main body side. When not, it is an elastic member having a slit in close contact.

  In this developing unit, when the leading end of the toner supply device enters the container main body, the slit of the elastic member is pushed wide so that the leading end of the toner supply device enters the container main body. Further, when the tip of the toner supply device is separated from the container body, the slit of the elastic member is in close contact.

  Here, since the slit is an elastic member, the structure of the toner supply device is simplified. In addition, the slit of the elastic member is in close contact except when the tip of the toner supply device enters the container body, thereby preventing the internal toner from leaking to the outside.

  The structure of the joint mechanism of the toner supply device and the developing device is simplified. Further, toner replacement can be easily performed, and toner leakage at the time of toner replacement can be suppressed.

  FIG. 1 shows a color printer 1 as an image forming apparatus employing a developing unit 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 as an exposure device, a toner storage unit 5, a toner supply device 6, an intermediate transfer belt 7, and a secondary transfer roller 8. And a fixing 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 rotary frame 15 has a cylindrical shape that is rotatable around an axis parallel to the rotation axis of the photosensitive drum 2 and is rotated by a drive mechanism including a motor and a gear (not shown). The rotating frame 15 has four sections divided into four equal parts 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. One of the four developing devices 16 is shown in FIG. Here, in the present invention, a toner storage portion (described later) is provided separately from the developing device 16, and therefore the toner storage space of the developing device itself of this embodiment is small, and the toner storage portion is placed inside the developing device. The developing device 16 itself is downsized as compared with the apparatus having the same. Further, the developing devices 16 are detachable, and maintenance of the developing devices is easy. Further, a toner supply unit 18 as shown in FIG. 3 is provided on the outer peripheral side of the case 17 of the developing unit 16 in order to supply the toner from the toner storage unit to the inside of the developing unit 16.

  The toner supply unit 18 is formed by forming an opening in a part of the case 17 and fixing an elastic member in which a slit 18a that is usually in close contact with the opening is formed.

[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 (first 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 beam path of the laser unit 4, and the laser light emitted from the laser unit 4 is bent by the reflection mirror 20 and irradiated onto the surface of the photosensitive drum 2. It has become so.

[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. The toner accommodating portion 5 is located above the photosensitive drum 2 and on the side facing the laser unit 4 (apparatus front side: first side). 2 side). 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]
The toner supply device 6 is for supplying the toner of each color stored in the toner storage unit 5 to the corresponding developing device 16, and above the photosensitive drum 2, the laser unit 4, the toner storage unit 5, and the like. Is arranged in the space between. As shown in FIG. 2, the toner supply device 6 includes four toner supply pipes 25 that are movable in the vertical direction, and a toner supply pipe 25 that corresponds to a portion of the toner storage unit 5 that stores toner of each color. Are connected to each other, a limit switch 70 for detecting a limit position of the upward movement of the toner supply device, and a drive mechanism 27 for moving each toner supply pipe 25 up and down. .

  The toner supply pipe 25 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 back side of the apparatus. The tip of the toner supply pipe 25 has a tapered shape, and when it moves downward, the tip can enter the inside through a slit 18 a formed in the toner supply unit 18 of the developing device 16. A toner conveying screw 30 is rotatably provided inside the toner supply pipe 25.

  The limit switch 70 detects a limit position when the rack 32 moves upward and downward, and is disposed on the upper side and the lower side of the toner supply device 6.

  The transport pipe 26 is a flexible pipe so that it can move following the vertical movement of the toner supply pipe 25. A coil spring 31 is disposed inside and rotated by a drive mechanism (not shown), whereby the toner passes through the transport pipe 26 and is transported to the toner supply pipe 25 side.

  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 in which the tip portion enters the inside of the developing device 16 at a lower position (FIG. Position indicated by a two-dot chain line). Here, as described above, the laser light of the laser unit 4 passes above the front side of the rotary developing device 3. That is, the laser beam path and the moving path of the toner supply pipe 25 intersect each other, and when the toner supply pipe 25 is positioned at the retracted position, the laser beam path is not blocked by the toner supply pipe 25, but the toner supply pipe. When the toner supply pipe 25 is located at the supply position, the laser light path is blocked by the toner supply pipe 25.

  Further, the movement of the tip of the toner supply pipe 25 during the toner supply operation is performed at a speed of 2 mm to 20 mm per second. Therefore, it is possible to move the toner supply pipe 25 even with a low torque brush motor, and it is possible to secure a force for expanding the slit 18a when the tip of the toner supply pipe 25 enters the developing device 16. .

  The toner supply pipe 25 has a shutter mechanism that opens only when the toner supply pipe 25 is located at the supply position. Specifically, as shown in FIG. 5, the toner supply pipe 25 has a double structure having an inner cylinder part 251 and an outer cylinder part 252. Openings 251a and 252a are formed in part of the circumferential direction. Here, the opening angle of the opening 252a of the outer cylinder part 252 is smaller than that of the opening 251a of the inner cylinder part 251. Further, the outer cylinder portion 252 has a protrusion formed on the outer peripheral surface, and this protrusion is disposed on the outer periphery of the outer cylinder portion and is engaged with the rotating cam 28 in which the spiral guide groove 28a is formed. In FIG. 4B, the rotating cam 28 is shown in an exploded manner for convenience. When the toner supply pipe 25 is in the upper retracted position, the inner cylinder opening 251a and the outer cylinder opening 252a do not coincide with each other (FIG. 5A: shutter closed), and the toner leaks to the outside. Absent. On the other hand, when the toner supply pipe 25 moves downward, the outer cylindrical portion 252 is rotated by the protrusion and the spiral guide groove 28 a of the rotary cam 28, and the tip of the toner supply pipe 25 enters the inside of the developing device 16. Then, when positioned at the supply position, the opening 251a of the inner cylinder portion and the opening 252a of the outer cylinder portion coincide with each other (FIG. 5 (b): shutter open), and the internal toner passes from the opening to the inside of the developing device 16. To be supplied.

[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 that are disposed to face each other. Further, the portion of the intermediate 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.

  The arrangement of these constituent members will be described in more detail. The driving roller 35 is located almost directly below the contact portion between the photosensitive drum 2 and the rotary developing device 3, and the center thereof is located further below the lowermost end of the rotary developing device 3. And it drives by the drive part containing the motor and gear which are not shown in figure. The driven roller 36 is disposed in the vicinity of the bottom of the toner container 5 on the front side of the apparatus, and the height position thereof is substantially the same as that of the photosensitive drum 2. The driven roller 36 is urged away from the driving roller 35 by a spring 38, whereby a predetermined tension is applied to the intermediate belt 7. The primary transfer rollers 37 a and 37 b are provided close to each other and below the photosensitive drum 2, so that a predetermined range of the transfer belt 7 is in contact with the photosensitive drum 2.

  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 the lowest on the laser unit 4 side (apparatus back side) and gradually increases as it goes to the toner storage unit 5 side (on 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.

[Paper Feeder and Transporter]
At the bottom of the apparatus, there is provided a paper feed cassette 52 that has a placement plate on which paper is placed and stores the paper. A paper feeding unit (paper feeding unit) 51 for feeding paper from the paper feeding cassette 52 is provided at a paper feeding side end (right end in FIG. 1) of the paper feeding cassette 52. The paper feed unit 51 includes a forward feed roller 53 for taking out the paper on the loading plate and a multi-feed prevention mechanism 54 including a pair of rollers for feeding the paper one by one to the transport path. The paper feed cassette 52 can be pulled out in the paper feed direction, that is, the front side of the apparatus.

  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.

  A manual feed tray 65 is disposed below the toner storage unit 5 and above the paper feed cassette 52 so as to form a side wall on the front side of the apparatus. The manual feed tray 65 is rotatably supported at its lower end in the vicinity of the curved path 55a of the first transport path 55 (openable and closable), and the upper end of the manual feed tray 65 is tilted toward the front side of the apparatus with the rotational fulcrum 65a as a center. Is possible. When the manual feed tray 65 is opened as described above, it is possible to place a sheet on the manual feed tray 65 and feed the sheet to the curved path 55 a of the first conveyance path 55.

In the transport unit for transporting the paper as described above, the paper feed cassette 52, the first transport path 55, the second transport path 56, the return transport path 59, and the manual feed tray 65 are integrated into a unit. The paper transport unit can be pulled out toward the front of the apparatus along the paper feed direction and the paper transport direction. [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.

  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 supply unit 51, one sheet of paper is taken out from the paper supply cassette 52 by the forward feed roller 54 and the double feed prevention mechanism 55 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 double-sided printing, the paper that has passed through the fixing device 9 is once transported to the third transport path 57 side by the branching claw 58, and then transported in the reverse direction when the trailing edge of the paper passes the branching claw 58. Then, it is guided to the return conveyance path 59 side and returned to the first conveyance path 55 again via the return conveyance path 59. 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.

[Toner supply operation]
When supplying toner to the developing device 16, the toner supply pipe 25 is moved downward so that the developing device 16 to which the toner is to be supplied is positioned at a supply position as shown in FIG. The rotation of the rotary developing device 3 is locked in this state. Next, the toner supply pipe 25 is moved downward to be positioned at the supply position. That is, when the motor 33a is driven, the pinion gear 33 rotates through the gear train, and thereby the toner supply pipe 25 to which the rack 32 is fixed moves downward. On the other hand, when the coil spring 31 in the transport pipe 26 rotates, the toner from the toner storage unit 5 is supplied to the toner supply pipe 25 side. The tip of the toner supply pipe 25 passes through the slit 18a as a toner supply port and enters the developing device 16. The tip of the toner supply pipe 25 passes through the slit 18a as a toner supply port and enters the developing device 16. When the toner supply pipe 25 moves downward, the outer cylinder portion 252 constituting the toner supply pipe 25 rotates with respect to the inner cylinder portion 251, and the tip of the toner supply pipe 25 enters the inside of the developing device 16. Then, the opening 252a of the outer cylinder part 252 and the opening 251a of the inner cylinder part 251 coincide. That is, the shutter mechanism is opened.

  When the toner supply pipe 25 is located at the supply position, the toner supply pipe 25 blocks the optical path from the laser unit 4 to the photosensitive drum 2. However, since the toner supply operation by the toner supply pipe 25 and the image forming operation are not executed simultaneously, there is no problem.

  When the toner supply is completed, the coil spring 31 in the transport pipe 26 stops rotating. On the other hand, the toner conveying screw 30 disposed inside the toner supply pipe 25 continues to rotate until the toner in the toner supply pipe 25 runs out. Thereafter, when the motor 33a is rotated in the opposite direction, the pinion gear 33 is rotated in the reverse direction, whereby the toner supply pipe 25 to which the rack 32 is fixed moves upward. At this time, the outer cylinder part 252 rotates in the opposite direction, the positions of the opening 251a of the inner cylinder part 251 and the opening 252a of the outer cylinder part 252 are shifted, and the opening is closed. That is, the shutter is closed. In the toner supply unit 18 provided on the developing device 16 side, when the toner supply pipe 25 comes out of the slit 18a, the slit 18a is closed by an elastic force. Therefore, the toner can be prevented from scattering from the toner supply pipe 25 and the developing device 16 into the apparatus.

  Note that the movement of the tip of the toner supply pipe 25 during the toner supply operation is performed at a speed of 2 mm to 20 mm per second. Therefore, the toner supply pipe 25 can be moved even with a low torque brush motor, and a force for entering the developing device 16 at the tip of the toner supply pipe 25 can be secured.

[Effect of this embodiment]
(A) Since the toner supply device 16 replenishes toner from the outside, the development unit can be downsized.

  (B) The structure of the joint part of the rotary and the toner supply unit is simplified, and the slit 18a of the rotary developing device 3 prevents toner leakage when supplying toner, and the possibility of contamination becomes low.

(C) Since each developing device can be attached and detached one by one, maintenance of the developing device is easy.
[Other Embodiments]
In the above-described embodiment, the limit device 70 is disposed on the upper side and the lower side of the toner supply device 6, but may be either the upper direction or the lower direction. Using a stepping motor, the movement distance is measured by the number of steps from the limit position where the limit device 70 is arranged, and the other limit position is determined.

1 is a schematic configuration diagram of a color printer according to an embodiment of the present invention. FIG. 3 is a detailed cross-sectional configuration diagram of a toner supply device. FIG. 3 is an external perspective view of a developing device. The perspective view of a toner supply pipe. The block diagram of the toner supply pipe front-end | tip.

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 Toner conveyance screw 31 Spring coil 70 Limit switch

Claims (9)

A container body having a developing roller therein;
An inner cylinder having an inner opening at the front end portion and an outer cylinder having an outer opening at the side surface of the front end portion, which is provided on the outer peripheral portion of the inner cylinder so as to be rotatable relative to the inner cylinder, and supplies toner to the container body A toner supply device,
A driving device for causing the tip of the toner supply device to enter the container main body and to be separated from the container main body;
When the tip of the toner supply device enters the container body, the inner opening of the inner cylinder and at least a part of the outer opening of the outer cylinder are matched, and the tip is positioned outside the container body. A developing mechanism comprising: a shutter mechanism for positioning the inner opening and the outer opening at times.   The developing unit according to claim 1, wherein the toner supply device has a toner conveying screw rotatably disposed inside the inner cylinder portion.   The developing unit according to claim 1, wherein an outer opening of the outer cylinder is larger than an inner opening of the inner cylinder portion.   The developing unit according to claim 1, wherein the shutter mechanism rotates the outer cylinder in accordance with driving of the toner supply device driven by the driving device.   5. The shutter mechanism according to claim 4, wherein the shutter mechanism includes a guide portion provided on an outer peripheral surface of the outer cylinder, and a spiral guide groove that is disposed on the outer peripheral portion of the outer cylinder and into which the guide portion is inserted. Development unit.   The developing unit according to claim 4, wherein the shutter mechanism includes a rack provided on an outer peripheral surface of the outer cylinder, and a pinion that is disposed on an outer peripheral portion of the outer cylinder and engages with the rack.   7. The developing unit according to claim 1, wherein a speed when the front end portion of the toner supply device enters or separates from the container main body is 2 mm to 20 mm per second. .   The developing unit according to claim 1, further comprising a limit switch that detects a limit position of at least one of upward movement and downward movement of the toner supply device.   The container body includes an elastic member having a slit that is in close contact with a portion where the tip of the toner supply device enters when the toner supply device does not enter the container body. Item 9. The developing unit according to any one of Items 1 to 8.

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