JP2006208988A - Development unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To simplify a structure of a drive mechanism of a toner supply pipe. <P>SOLUTION: The development unit has a plurality of development units 16, a plurality of toner supply pipes 25, the drive mechanism 27 and a shutter mechanism. The plurality of toner supply pipes 25 are provided corresponding to the plurality of development units 16 and each of which has a toner supply port and supplies toner to the corresponding development unit 16. The drive mechanism 27 is the one for simultaneously transfer the plurality of toner supply pipes 25 so that toner supply ports of the plurality of toner supply pipes 25 may take supply positions where they can be located inside the development units and save positions where they are located outside the development units. The shutter mechanism is the one which makes the toner supply ports into open states when the toner supply pipes 25 are located at the supply positions and inside the developing units and makes the toner supply ports into closed states when the toner supply pipes 25 are located at the save positions and located at the supply positions and outside the developing units. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a developing unit, and more particularly to a developing unit used in a full-color image forming apparatus of a system 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 transfer material of the photosensitive drum. 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 developing 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 configuration for supplying toner consumed during image formation, a configuration is provided in which a toner container is provided outside the developing unit and toner is supplied from the outside, as disclosed in Japanese Patent Laid-Open No. 10-198149. Has been. In the developing device described in this publication, a toner supply pipe is inserted into the developing device for each color to which toner is desired to be supplied.
JP-A-10-1981149

  When a toner supply pipe corresponding to a color to be supplied is driven for each color to which toner is to be supplied as in the developing device described in JP-A-10-198149, a drive mechanism for the toner supply pipe is provided for each color. Therefore, the number of parts of the drive mechanism increases and the structure becomes complicated. Furthermore, since the number of parts increases, the reliability of control of the drive mechanism also decreases.

  SUMMARY OF THE INVENTION An object of the present invention is to simplify the structure of a drive mechanism for a toner supply pipe and make it easier to control.

  A developing unit according to a first aspect includes a plurality of container bodies, a plurality of toner supply members, a driving device, and a shutter mechanism. Each of the plurality of container main bodies has a developing roller corresponding to each color. The plurality of toner supply members are provided corresponding to the plurality of container main bodies, each of which has a toner supply port and supplies toner to the corresponding container main body. The driving device simultaneously moves the plurality of toner supply members so that the toner supply ports of the plurality of toner supply members can take a toner supply position that can be located inside the container body and a retracted position that is located outside the container body. It is a device for making it. The shutter mechanism opens the toner supply port when the toner supply member is located at the toner supply position and within the container main body, and is located at the retracted position and the toner supply position outside the container main body. In this mechanism, the toner supply port is closed when the toner is being supplied.

  In this apparatus, when supplying toner, a plurality of toner supply members are moved to a toner supply position by a driving device. Only the toner supply port of the toner supply member located at the toner supply position and inside the container main body is opened by the shutter mechanism, and the toner is supplied. Further, the toner supply port is closed by the shutter mechanism for the toner supply member at the retracted position and the toner supply member at the toner supply position and outside the container main body.

  Here, each of the toner supply members provided corresponding to each color is not driven, but a plurality of toner supply members are driven at the same time, so that the toner supply member drive mechanism and its control become easy.

  A developing unit according to a second aspect is the developing unit according to the first aspect, wherein each of the plurality of container main bodies has an inlet through which a toner supply port of a corresponding toner supply member can enter the container main body, and corresponds. A recess is provided to prevent the toner supply port other than the toner supply member from entering the container body.

  Here, each of the plurality of container main bodies is formed with an entrance through which the toner supply member can enter and a recess for avoiding the toner supply member from entering the inside of the container main body. Accordingly, when supplying toner, all of the plurality of toner supply members are driven and moved to the toner supply position. However, the toner supply member enters the inside of the container body only from the entrance to the container body to which the toner is to be supplied, and is released by the shutter mechanism. The toner supply port is opened. On the other hand, the other toner supply members enter the recesses of the container body. Therefore, although the other toner supply members are located at the toner supply position, they are outside the container main body, so that the toner supply port is closed.

  A developing unit according to a third aspect is the developing unit according to the first or second aspect, wherein the container body has an elastic member having a slit as an entrance. Here, the toner supply member can easily enter the container body, and the internal toner can be prevented from leaking to the outside. Therefore, the shutter configuration on the container body side is simplified.

  According to a fourth aspect of the present invention, the development unit according to any one of the first to third aspects further includes a detection device that detects that the toner supply member has moved to the toner supply position, and the toner supply member is at the toner supply position. It has a control part which stops the drive by a drive device, when moving.

  According to a fifth aspect of the present invention, in the development unit according to any one of the first to fourth aspects, the driving device cuts off the driving of the toner supply member by the driving device when the toner supply member is located at the toner supply position. Have a clutch for.

  In this apparatus, when the toner supply member moves to the toner supply position, power transmission is interrupted by the clutch. For this reason, the burden on the drive source is reduced.

  According to a sixth aspect of the present invention, the developing unit of the fifth aspect further includes a position holding mechanism for restricting the movement of the toner supply member when the toner supply member is positioned at the toner supply position.

  In this apparatus, when the toner supply member is located at the toner supply position, the movement is restricted by the position holding mechanism. Therefore, the position of the toner supply member can be maintained even if the drive from the drive device is interrupted by the clutch.

  The developing unit according to claim 7 is the developing unit according to claim 6, wherein the driving device releases the holding of the position holding mechanism when the toner supply is completed and the biasing member that biases the toner supply member to the retracted position. And release means.

  In this apparatus, when the toner supply is completed, the holding of the toner supply member by the position holding mechanism is released. The toner supply member is moved to the retracted position by the urging member.

  The developing unit according to an eighth aspect is the developing unit according to the seventh aspect, wherein the release means releases the holding of the position holding mechanism when the power of the apparatus is turned off. Here, when the power is turned off at the time of toner supply, the holding of the toner supply member is released by the release means. As a result, the toner supply member is moved to the retracted position by the urging member. Therefore, it is possible to prevent the apparatus from being activated while the toner supply member enters the container body.

  A developing unit according to a ninth aspect is the developing unit according to the eighth aspect, further comprising a rotating frame for holding the plurality of container main bodies and for positioning each container main body at a predetermined position by rotating.

  Here, the container main body is held by the rotating frame. Accordingly, when the toner is supplied and the power is turned off and the apparatus is restarted, the rotating frame may rotate. At this time, if the rotating frame rotates while the toner supply member enters the inside of the container main body, each part may be damaged.

  Therefore, in this apparatus, when the power is turned off, the toner supply member is retracted to the retracted position by the biasing member as described above, and is positioned outside the container main body.

  According to a tenth aspect of the present invention, in the developing unit according to any one of the first to ninth aspects, the toner supply member is rotatable relative to the inner cylinder having an inner opening at the tip and the inner cylinder at the outer peripheral portion of the inner cylinder. An outer cylinder having an outer opening on the side surface of the distal end portion, and when entering 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 distal end portion is the container body And a shutter mechanism for positioning the inner opening and the outer opening at positions shifted from each other.

  In this apparatus, when the toner supply pipe moves to the toner supply position, the opening of the inner cylinder and the opening of the outer cylinder coincide with each other to supply the toner. In other cases, the opening of the inner cylinder and the opening of the outer cylinder coincide with each other. Toner does not leak outside.

  In the present invention, the driving mechanism of the toner supply member is simplified and the control thereof is facilitated.

  FIG. 1 shows a color printer 1 as a full-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 container 5, a toner supply device 6, an intermediate transfer belt 7, a secondary transfer roller 8, and a fixing device 9. And have.

[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 this embodiment, since the toner container (described later) is provided separately from the developing device 16, in order to supply toner from the toner container to the inside of the developing device 16, A toner supply unit 18 as shown in FIG. 2 is provided in the case (container body) 17. The toner supply unit 18 is formed by forming an opening in a part of the case 17 and fixing an elastic member having a slit 18a formed in the opening. The developing device 16 shown in FIG. 2 is a developing device corresponding to yellow, and therefore, an elastic member 18 as a toner supplying portion is formed only at a position where yellow toner is supplied, and supplying corresponding to other colors. A concave portion 17a having the same shape is formed at each position.

[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 (the front side of the device). Has been placed. As shown in FIG. 5, the toner storage unit 5 includes four storage units that store toner of each color of yellow, cyan, magenta, and black arranged in the horizontal direction (the vertical direction in FIG. 1). Have. 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 FIGS. 3 and 4, the toner supply device 6 includes four toner supply pipes 25 that are movable in the vertical direction, and a toner supply corresponding to a portion of the toner storage portion 5 that stores toner of each color. There are four transport pipes 26 that connect the pipes 25 and a drive mechanism 27 that simultaneously moves the four toner supply pipes 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 toner supply pipe 25 has a tapered tip, and when the toner supply pipe 25 moves downward, the tip can enter the inside through a slit 18 a formed in the elastic member 18 of the developing device 16. . A spiral member 30 for conveying toner is rotatably provided inside the toner supply pipe 25.

  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 has four toner supply pipes 25 so that the tip of the toner supply pipe 25 can take a supply position where the toner supply pipe 25 can be located inside the developing unit 16 and a retracted position located outside the developing unit 16. Is a mechanism for moving the two at the same time. The drive mechanism 27 includes a motor (not shown), a gear train 70, a clutch 71, a drive shaft 72, a rack 32 provided in the outer peripheral portion of each toner supply pipe 25 along the axial direction, There are four pinion gears 33 that mesh with the rack 32. The clutch 71 is provided between the motor and the gear train 70, and is for transmitting or interrupting the power of the motor. The drive shaft 72 is provided along the rotation axis of the rotary developing device 3 and has substantially the same length as the length of the developing device 16. Four pinion gears 33 are fixed to the drive shaft 72.

  By such a drive mechanism 27, the four toner supply pipes 25 are simultaneously provided at the upper retracted position (the position indicated by the solid line in FIG. 1) and at the lower supply position where the tip portion has entered the inside of the developing device 16 (FIG. 1) (position indicated by a two-dot chain line). As shown in FIG. 3, an upper limit detection sensor 75a for detecting that the toner supply pipe 25 has moved to the retracted position (upper limit position) and a lower limit detection sensor 75b for detecting movement to the supply position are provided. It has been.

  The drive shaft 72 is provided with a locking mechanism (position holding mechanism) 80 that restricts the movement of the toner supply pipe 25 when the toner supply pipe 25 is located at the supply position. As shown in FIG. 5, the locking mechanism 80 is provided at an end portion (not shown in FIG. 4) of the drive shaft 72, and a first locking member 81 fixed to the drive shaft 72, A solenoid 82 and a second locking member 83 rotated by the solenoid 82 are provided. The first locking member 81 has a first locking portion 81a that protrudes in a direction orthogonal to the axial direction. The solenoid 82 is configured such that when a voltage is applied, the rod 84 protrudes, and when no voltage is applied, the rod 84 is retracted by an internal spring. The second locking member 83 has an inverted L shape, and a lower end portion is rotatably connected to a rod 84 of the solenoid 82. When the drive shaft 72 rotates and the toner supply pipe 25 is located at the supply position and the voltage is applied to the solenoid 82, the second locking portion 83a on the upper side of the second locking member 83 is It can be locked to one locking portion 81a.

  A coiled torsion spring 85 is provided around the drive shaft 72 as shown in FIG. One end (not shown) of the torsion spring 85 is locked to a fixed member, and the other end is locked to a spring locking member 86 fixed to the drive shaft 72. The torsion spring 85 urges the drive shaft 72 in the A direction in FIG. 5. Therefore, in a state where the drive force is not applied to the drive shaft 72, the torsion spring 85 causes the drive shaft 72 to move in the A direction. The toner supply pipe 25 is moved upward.

  Next, the structure of the toner supply pipe 25 will be described in detail with reference to FIGS. 6 and 7, and the shutter mechanism of the present embodiment will be described together.

  The shutter mechanism opens the toner supply port of the toner supply pipe 25 when the toner supply pipe 25 is located at the supply position and inside the developing device 16, and develops at the retreat position and the supply position. This is a mechanism for closing the toner supply port when the toner supply port is located outside the container 16. This shutter mechanism is configured as follows.

  The toner supply pipe 25 includes an inner cylinder part 251, an outer cylinder part 252 disposed on the outer periphery of the inner cylinder part 251, and a pipe guide member 100 disposed on the outer periphery of the outer cylinder part 252. In FIG. 6, the pipe guide member 100 is omitted.

  The inner cylinder part 251 and the outer cylinder part 252 can be rotated relative to each other and cannot be moved in the axial direction. The outer cylinder part 252 and the pipe guide member 100 can be rotated relative to each other in the axial direction. Movement is also possible. In addition, a pipe holding member 104 (only a part of which is shown in FIG. 4 and substantially half omitted) is fixed to the frame of the color printer, and the pipe guide member 100 is guided by the pipe holding member 104. Has been moved up and down. In addition, the pipe guide member 100 and the pipe holding member 104 cannot be rotated relative to each other and can move in the axial direction.

  The pipe guide member 100 is shorter than the length of the outer cylindrical portion 252, the upper portion of the outer cylindrical portion 252 protrudes from the upper end of the pipe guide member 100, and the lower portions of the inner cylindrical portion 251 and the outer cylindrical portion 252 are further extended from the lower end of the pipe guide member 100. It protrudes. A flange 252a having a diameter larger than that of the other portion is formed at the upper end of the outer cylindrical portion 252, and the upper surface of the flange 252a is a pressing portion 32a provided on the rack 32 (see FIG. 7; see FIGS. 3 and 3). (Not shown in FIG. 4). A spring 101 is provided between the flange 252 a and the upper end surface of the pipe guide member 100. Furthermore, a flange 100a having a larger diameter than the outer diameter of the other part is formed at the lower end of the pipe guide member 100. The outer diameter of the flange 100 a is set to be larger than the length of the slit 18 a formed in the elastic member 18 and smaller than the diameter of the recess 17 a formed in the case 17 of the developing device 16.

  As shown in FIG. 7, the pipe guide member 100 has a spiral groove 100b formed therein, and the outer cylinder 252 has a protrusion 252b that engages with the spiral groove 100b. Here, openings 251a and 252a are formed in a part in the circumferential direction at the distal ends of the inner cylinder portion 251 and the outer cylinder portion 252. When the toner supply pipe 25 is in the upper retracted position, the opening 251a of the inner cylinder portion 251 and the opening 252a of the outer cylinder portion 252 do not coincide (FIG. 6A: shutter closed), and the toner is exposed to the outside. Does not leak. On the other hand, the toner supply pipe 25 moves downward, the flange 100a of the pipe guide member 100 comes into contact with the elastic member 18 of the toner supply part, the pipe guide member 100 stops, and the inner cylinder part 251 and the outer cylinder part 252 When the shutter moves further downward, the shutter is opened. That is, the outer cylinder part 252 is rotated by the engagement between the protrusion 252b and the spiral groove 100b of the pipe guide member 100, and the opening 251a of the inner cylinder part 251 and the opening 252a of the outer cylinder part 252 coincide (FIG. 6B). ) And (c): shutter open), the toner inside is supplied to the inside of the developing device 16 from the openings 251a and 252a.

[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 transfer belt 7 that faces the photosensitive drum 2 is configured to contact 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 that is 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]
At the bottom of the apparatus, there is provided a paper feeding unit 51 for storing paper and sending out the stored paper. The paper feed unit 51 has a paper feed cassette 52 having a placement plate on which paper is placed, a forward feed roller 53 for taking out the paper on the placement plate, and for feeding the paper one by one to the transport path. And a double feed prevention mechanism 54 composed of a pair of rollers. The paper feed cassette 52 can be pulled out to the front side of the apparatus.

[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. Further, a branch claw 58 is provided at the outlet of the fixing device 9, and a return conveyance path for returning the sheet to the first conveyance path 55 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 sheet feeding 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 feeding 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 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 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.

[Toner supply operation]
When supplying toner to the developing device 16, the rotary developing device 3 is rotated 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 by the drive mechanism 27. That is, when the motor is driven, the drive shaft 72 and the pinion gear 33 are rotated via the clutch 71 and the gear train 70, whereby the rack 32 and the pressing portion 32a are moved downward. For this reason, the four toner supply pipes 25 simultaneously move 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.

  Here, for example, when supplying toner to a developing device 16 (hereinafter referred to as a yellow developing device) 16 corresponding to yellow, the yellow developing device 16 is positioned at a supply position as shown in FIG. As shown in FIG. 2, the yellow developing unit 16 is provided with an elastic member 18 having a slit 18a formed only in the frontmost part of the drawing. The position where the elastic member 18 is provided is a position corresponding to a toner supply pipe (hereinafter, referred to as a yellow toner supply pipe) 25 to which yellow toner is supplied. On the other hand, in the yellow developing device 16, a concave portion 17a is formed at a position corresponding to the toner supply pipe 25 to which other color toner is supplied.

  When the four toner supply pipes 25 move downward in the state as described above, the tip of the yellow toner supply pipe 25 has a slit 18a of the elastic member 18 as shown in FIG. And the flange 100a of the pipe guide member 100 abuts against the elastic member 18. Accordingly, thereafter, the lowering of the pipe guide member 100 is stopped, and only the inner cylinder portion 251 and the outer cylinder portion 252 are further lowered. At this time, the spring 101 provided between the upper end surface of the pipe guide member 100 and the flange 252a of the outer cylinder portion 252 contracts.

  When the inner cylinder part 251 and the outer cylinder part 252 are further lowered, the outer cylinder part 252 moves with respect to the pipe guide member 100, so that the projection 252 b of the outer cylinder part 252 moves along the spiral groove 100 b of the pipe guide member 100. As a result, the outer cylindrical portion 252 rotates with respect to the inner cylindrical portion 251. Accordingly, when the tip of the toner supply pipe 25 enters the inside of the developing device 16 and reaches the supply position, the opening 252a of the outer cylinder portion 252 and the opening of the inner cylinder portion 251 are shown in FIG. 251a matches. That is, the shutter mechanism is opened.

  When the lower limit sensor 75b detects that the toner supply pipe 25 has reached the supply position, a voltage is applied to the solenoid 82. Then, the rod 84 of the solenoid 82 protrudes, and the second locking member 83 rotates counterclockwise in FIG. Then, the second locking portion 83 a of the second locking member 83 is locked to the first locking portion 81 a of the first locking member 81 fixed to the drive shaft 72. After this locking, the clutch 71 is actuated (off), and the power from the motor to the gear train 70 is cut off. Here, the first locking member 81 of the drive shaft 72 is locked by the second locking member 83, the rotation thereof, that is, the movement of the toner supply pipe 25 is restricted, and the drive shaft 72 is driven by the torsion spring 85. Since the supply pipe 25 is urged to move upward, the position of the toner supply pipe 25 is maintained even when the driving force is interrupted by the clutch 71.

  When the toner supply is completed, the application of voltage to the solenoid 82 is stopped while the clutch 71 is kept off. As a result, the rod 84 of the solenoid 82 is retracted, and the second locking member 83 is rotated in the opposite direction. As a result, the locking of the second locking member 83 to the first locking member 81 is released, the drive shaft 72 is rotated by the spring force of the torsion spring 85, and the toner supply pipe 25 returns to the upper retracted position.

  On the other hand, when supplying the yellow toner described above, the toner supply pipes 25 other than the yellow toner supply pipe 25 enter the recess 17a of the yellow developing device 16, as shown in FIG. In this case, the flange 100a of the pipe guide member 100 also enters the recess 17a, and movement is not restricted. That is, the pipe guide member 100 is lowered together with the outer cylinder portion 252 and relative movement does not occur between them. For this reason, the outer cylinder part 252 does not rotate with respect to the inner cylinder part 251, and the opening 251a of the inner cylinder part 251 and the opening 252a of the outer cylinder part 252 remain inconsistent. That is, the shutter is closed.

  Here, the toner supply pipe 25 enters the inside of the developing device 16 at the time of toner supply, but the case where the power supply is cut off for some reason is considered. When the power is turned off and then restarted, the rotary developing device 3 rotates for initial setting. At this time, if the toner supply pipe 25 remains in the developing device 16, the developing device 16 or the toner supply pipe 25 may be damaged.

  However, in this embodiment, when the power is turned off, no voltage is applied to the solenoid 82, so that the rod 84 is retracted, the drive shaft 72 is unlocked, and the torsion spring 85 returns to the retracted position. It is like that. Therefore, even if the power is cut off during toner supply due to some abnormality, damage to the rotary developing device 3 and the toner supply pipe 25 can be avoided.

1 is a schematic configuration diagram of a color printer according to an embodiment of the present invention. FIG. 3 is an external perspective view of a developing device. FIG. 3 is a detailed cross-sectional configuration diagram of a toner supply device. FIG. 3 is an external view of a toner supply pipe and a driving mechanism thereof. FIG. FIG. 3 is a cross-sectional configuration diagram of a toner supply pipe. FIG. 6 is a diagram for explaining an operation of a toner supply pipe and a shutter mechanism. FIG. 6 is a diagram for explaining an operation of a toner supply pipe and a shutter mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Color printer 3 Rotating developing device 6 Toner supply device 16 Developing device 17 Case 17a Recessed portion 18 Elastic portion seat 18a Slit 25 Toner supply pipe 27 Drive mechanism 71 Clutch 81 First locking member 82 Solenoid 83 Second locking member 251 Inner cylinder Part 251a, 252a opening 252 outer cylinder part

Claims (10)

A plurality of container main bodies each having a developing roller corresponding to each color;
A plurality of toner supply members provided corresponding to the plurality of container main bodies, each having a toner supply port and supplying toner to the corresponding container main body;
The plurality of toner supply members are simultaneously moved so that the toner supply ports of the plurality of toner supply members can take a toner supply position that can be located inside the container body and a retracted position that is located outside the container body. A driving device for causing
When the toner supply member is located at the toner supply position and within the container body, the toner supply port is opened, and the retracted position and the toner supply position are outside the container body. A shutter mechanism that closes the toner supply port when positioned,
Development unit equipped with.   Each of the plurality of container bodies has an entrance through which a toner supply port of the corresponding toner supply member can enter the container body, and a toner supply port other than the corresponding toner supply member is in the container body. The developing unit according to claim 1, wherein the developing unit has a concave portion for avoiding entering.   The developing unit according to claim 1, wherein the container body includes an elastic member having a slit as the entrance. A detection device for detecting that the toner supply member has moved to the toner supply position;
A control unit that stops driving by the driving device when the toner supply member moves to the toner supply position;
The developing unit according to claim 1.   5. The drive device according to claim 1, wherein the drive device includes a clutch for interrupting driving of the toner supply member by the drive device when the toner supply member is located at the toner supply position. The developing unit according to 1.   The developing unit according to claim 5, further comprising a position holding mechanism that restricts movement of the toner supply member when the toner supply member is positioned at the toner supply position.   The drive device includes an urging member that urges the toner supply member to the retracted position, and a release unit that releases the holding of the position holding mechanism when the toner supply is completed. The developing unit according to 1.   The developing unit according to claim 7, wherein the release unit releases the holding of the position holding mechanism when the power of the apparatus is turned off.   The developing unit according to claim 8, further comprising a rotating frame that holds the plurality of container main bodies and rotates the container main bodies at predetermined positions by rotating. The toner supply member includes an inner cylinder having an inner opening at a front end portion, and an outer cylinder provided on an outer peripheral portion of the inner cylinder so as to be relatively rotatable with the inner cylinder and having an outer opening on a side surface of the front end portion. When entering the container body, the inner opening of the inner cylinder and at least a part of the outer opening of the outer cylinder are made to coincide with each other, and the inner opening and the outer opening are positioned when the tip portion is located outside the container body. A shutter mechanism for positioning the
The developing unit according to claim 1.

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