JP2007065391A - Developing unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the breakage of a toner supply member and a developing device when the power source is turned on again even after electric power is shut off in such a situation that the toner supply member enters the developing device. <P>SOLUTION: The developing unit includes a developing device 16, a toner supply pipe 25, a driving mechanism 27, a position keeping mechanism 80 and an emergency driving mechanism 90. The driving mechanism 27 functions as a mechanism of moving the toner supply pipe 25 so that the toner supply pipe 25 may be positioned in a toner supply position where the toner supply port is positioned in the developing device 16 and a retreat position where the toner supply pipe 25 is positioned outside the developing device 16. The retreat mechanism 90 releases the movement control of the toner supply pipe 25 by the position keeping mechanism 80 when the electric power is shut off in such the situation that the toner supply pipe 25 is positioned in the toner supply position, and positions the toner supply pipe 25 in the retreat position. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a developing unit, and more particularly to a developing unit used in 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 transfer material conveyance direction. 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 method for supplying toner consumed in image formation, there is a method in which a toner container is provided outside a developing unit and toner is supplied from the outside as disclosed in Japanese Patent Laid-Open No. 10-198149. In the developing device described in this publication, toner is supplied by causing a toner supply member to enter the developing device for each color to be supplied with toner.
JP 10-1981149 A

  As described in Japanese Patent Application Laid-Open No. 10-198149, in a device for supplying toner by causing a toner supply member to enter the developing device, the toner supply member is attached to the developing device when the power is cut off during the toner supply operation. The operation of the developing device is stopped in the entered state. After that, when the power is turned on again, it is impossible to recognize that the toner supply member has entered the developing device, and there is a risk that the developing device will rotate for initial setting while the toner supply member has been entered. There is. In such a case, the toner supply member or the developing device may be damaged.

  An object of the present invention is to prevent the toner supply member and the developing device from being damaged when the power is turned on again even when the power is cut off while the toner supply member enters the developing device.

  A developing unit according to a first aspect includes a container main body, a toner supply member, a drive mechanism, a position holding mechanism, and a retracting mechanism. Each of the plurality of container main bodies has a developing roller corresponding to each color. The toner supply members each have a toner supply port and supply toner to each of the plurality of container bodies. The drive mechanism moves the toner supply member so that the toner supply member can take a toner supply position where the toner supply port is located inside the container body and a retracted position where the toner supply member is located outside the container body. Mechanism. The position holding mechanism regulates movement of the toner supply member in a state where the toner supply member is located at the toner supply position. When the power is cut off in a state where the toner supply member is in the toner supply position, the retracting mechanism releases the restriction of movement of the toner supply member by the position holding mechanism and positions the toner supply member in the retracted position.

  In this developing unit, when supplying the toner, the toner supply member is moved to the toner supply position by the drive mechanism, and the toner is supplied from the toner supply member to the container body. In a state where the toner supply member is positioned at the toner supply position, the movement of the toner supply member is regulated by the position holding mechanism. When power is cut off while the toner supply member is in the toner supply position, the movement restriction of the toner supply member by the position holding mechanism is released by the retraction mechanism, and the toner supply member moves to the retraction position. To do.

  Here, since the toner supply member is retracted to the retracted position when the power is cut off during toner supply, the toner supply member and the development device are rotated along with the rotation of the developing device for initial setting when the power is turned on again. Can reduce the risk of breakage.

  The developing unit according to claim 2 is the developing unit according to claim 1, wherein the position holding mechanism is locked to the first locking portion fixed to the toner supply member and the first locking portion. A second locking member.

  In the developing unit, when the toner supply member is located at the toner supply position, the first locking portion and the second locking member fixed to the toner supply member are locked with each other. Accordingly, the movement of the first locking portion is restricted, so that the position of the toner supply member is held at the toner supply position.

  A developing unit according to a third aspect is the developing unit according to the first or second aspect, wherein the retracting mechanism is configured to release the locking between the first locking portion and the second locking member. A second locking member driving device that moves the locking member; and a biasing member that biases the toner supply member to be positioned at the retracted position.

  In the developing unit, when the power is cut off during the toner supply, the second locking member driving device releases the locking between the first locking portion and the second locking member. Move. As a result, the toner supply member can be moved. The toner supply member is urged to move to the retracted position by the urging member.

  A developing unit according to a fourth aspect is the developing unit according to the second or third aspect, wherein the position holding mechanism is configured such that the first engaging portion is engaged with the second engaging member. A second locking member moving member for moving the stopping member is further provided.

  In the developing unit, the second locking member is moved by the second locking member moving member so that the first locking portion is locked with the second locking member, and the first locking portion and the second locking member are moved. The stop members are locked together.

  A developing unit according to a fifth aspect is the developing unit according to the third aspect, wherein the second locking member driving device is a biasing member.

  A developing unit according to a sixth aspect is the developing unit according to any one of the first to fifth aspects, wherein the toner supply port is opened when the toner supply position is located, and the toner is supplied to the retreat position. A shutter mechanism that closes the toner supply port when the member is positioned is further provided.

  In this developing unit, when the toner supply member is located at the toner supply position, the toner supply port is opened, and toner is supplied from the toner supply device to the container main body. When the toner supply member is located at the retracted position, Since the toner supply port is closed, the toner is less likely to leak to the outside.

  A developing unit according to a seventh aspect is the developing unit according to any one of the first to sixth aspects, wherein the container main body is a slit through which the toner supply member passes when moving between the retracted position and the toner supply position. The elastic member which has is provided.

  In this developing unit, when supplying toner, the toner supply member passes through the slit of the elastic member of the container body and enters the inside of the container body to supply the toner. When the toner supply is completed, the toner supply member is retracted to the retracted position by the drive mechanism. At this time, since the elastic member having the slit is brought into close contact by the elastic force, the toner does not leak to the outside.

  Here, an elastic member having a slit is disposed at a portion of the developing device where the toner supply member enters. In such a developing device, if the power is cut off when the toner is supplied, there is a possibility that the state in which the toner supply member enters the developing device continues for a long time. If the toner supply member enters the developing device for a long time, the elastic member cures while the toner supply member enters the slit, so that the slit remains in contact even when the toner supply member moves to the retracted position. It may be difficult to become. As described above, if the slit of the elastic member is not in a close contact state, the internal toner leaks to the outside as the developing device rotates. However, in the invention according to the present invention, even when the power is cut off when the toner is supplied, the movement restriction of the toner supply member by the position holding mechanism is released by the retraction mechanism, and the toner supply member moves to the retraction position. Therefore, it is possible to prevent the toner supply member from entering the developing device from continuing for a long time.

  In the present invention, it is possible to reduce the risk of the toner supply member and the developing device being damaged even when the power is cut off when the toner is supplied and the developing device is rotated thereafter. Further, even when the shutter mechanism on the container body side is constituted by an elastic member having a slit, the elastic member can be prevented from being cured while the toner supply member has entered the slit of the elastic member, thereby preventing toner leakage. Can do.

  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 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 container (described later) is provided separately from the developing device 16. In addition, a toner supply unit 18 is provided on the outer peripheral side of the case of the developing device 16 in order to supply toner from the toner storage unit to the inside of the developing device 16. 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.

[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]
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. 4 to 9, the toner supply device 6 includes four toner supply pipes 25 that can move in the vertical direction, and a toner supply corresponding to a portion of the toner storage portion 5 that stores toner of each color. Four transport pipes 26 connecting the pipes 25, a drive mechanism 27 for moving the toner supply pipes 25 up and down, and restricting the movement of the toner supply pipes when the toner supply pipes 25 are positioned at the toner supply positions. The position holding mechanism 80 and a retracting mechanism 90 for positioning the toner supply pipe 25 at the retracted position when the power is cut off when the toner supply pipe 25 is positioned at the toner supply position.

<Toner supply pipe 25 and transport pipe 26>
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. Further, 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 toner supply portion 18 of the developing device 16. is there. A spiral member 30 for conveying toner is rotatably provided inside the toner supply pipe 25.

  3 is a cross-sectional view of the toner supply pipe 25 and the transport pipe 26. As shown in FIG. 3, the transport pipe 26 is flexible so that it can move following the vertical movement of the toner supply pipe 25. It is a pipe having. 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.

<Drive mechanism 27>
FIG. 4A shows the external appearance of the drive mechanism 27. The drive mechanism 27 includes a motor (not shown), a clutch 33 a, a rack 32 provided along the axial direction on the outer peripheral portion of the toner supply pipe 25, and a pinion gear 33 that meshes with the rack 32. The drive mechanism 27 causes the toner supply pipe 25 to move upwardly from a retracted position (a position indicated by a solid line in FIG. 1) and to a supply position where the tip portion enters the inside of the developing device 16 at a lower position (indicated by a two-dot chain line in FIG. 1). The position shown). In the frame 76 of the color printer 1, holes 85 through which the toner supply pipe 25 can pass are arranged at positions corresponding to the toner supply pipes 25 of the respective colors as shown in FIG. Passes through the hole 85 and moves to the toner supply position.

  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.

<Position holding mechanism>
FIG. 7 shows the toner supply pipe 25 taken out, FIG. 8 is a plan view in which a part of the toner supply device is disassembled, and FIG. 9 is a diagram showing a holding state in which a solenoid 74 described later is energized. FIG. 10 is a diagram showing a retracted state in which energization of a solenoid 74 described later is stopped. As shown in these drawings, the position holding mechanism 80 includes a locking protrusion 71 (first locking portion) fixed to the toner supply pipe 25 and a locking plate 73 (supported by the frame 76 of the color printer 1). A second locking member), and a lever 77 and a solenoid 74 for moving the locking plate 73.

  As shown in FIG. 7, the locking protrusion 71 is an L-shaped member fixed near the conveying pipe 26 side of the toner supply pipe 25, and moves up and down together with the toner supply pipe 25. The locking plate 73 is a belt-like plate member as shown by hatching in FIGS. 8 to 10, extends in the direction in which the four toner supply pipes 25 are arranged, and is movable in the longitudinal direction with respect to the frame 76. It is supported by. The locking plate 73 is formed with four square holes 72 through which the locking protrusions 71 of the toner supply pipes 25 can pass. Although details will be described later, after the locking projection 71 passes through the square hole 72 of the locking plate 73, the locking projection 71 is locked to the locking plate 73 by moving the locking plate 73 in the longitudinal direction. Is configured to do.

  Further, as shown in FIG. 8, the solenoid 74 is fixed to the frame 76 on one end side of the locking plate 73. A coil spring 75 is disposed on the other end side of the locking plate 73 between the other end of the locking plate 73 and the frame 76. By this coil spring 75, the locking plate 73 is always urged toward the solenoid 74 (right side in FIG. 8).

  Here, as is apparent from FIG. 11 schematically showing the operation of the solenoid 74, the lever 77 is attached to the tip end of the plunger 74 a of the solenoid 74. More specifically, the lever 77 is formed in a substantially C-shape, and is rotatably supported by the frame 76 with one end of the upper portion 77a serving as a fulcrum, and the solenoid 74 on the other end (tip) side of the upper portion. The tip end of the plunger 74a is engaged so as to be rotatable and slidable. FIG. 12 shows a view of the lever 77 as viewed from above, and as is clear from FIG. 12, the lower portion 77b of the lever 77 is tapered so that the side portion on the side of the locking plate 73 is tapered. The inclined surface 77 c is in contact with the other end side of the locking plate 73. The portion of the locking plate 73 that comes into contact with the lever 77 has a portion 73a that is bent upward, and a portion 73b that is bent in the direction in which the locking plate 73 extends from the bent portion 73a. ing. Thus, as will be described later, the lever 77 and the locking plate 73 are smoothly slid relative to each other.

  A coil spring 81 for urging the lever 77 in a direction away from the locking plate 73 is provided at the intermediate portion 77 d of the lever 77. Therefore, when the solenoid 74 is not energized, the lever 77 always maintains the posture of FIG.

<Retreat mechanism>
The retracting mechanism 90 has the coil spring 75 (see FIG. 8) disposed on the other end side of the locking plate 73 and the torsion spring 70 shown in FIG. 6 is a view of the toner supply pipe 25 as seen from a cross section different from that of FIG.

  As described above, the coil spring 75 is disposed between the other end of the locking plate 73 and the frame 76, and always biases the locking plate 73 to one end side (solenoid 74 side). The torsion spring 70 is attached to the frame 76 via an attachment member (not shown), and one end is locked to the toner supply pipe 25 and the other end is locked to the frame 76. By the torsion spring 70, the toner supply pipe 25 is always urged upward (the retracted position side).

<Shutter mechanism>
The toner supply pipe 25 has a shutter mechanism that opens only when the toner supply pipe 25 is located at the supply position. FIG. 5 is a view showing an opening / closing mechanism at the tip of the toner supply pipe 25. 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 a part in 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, as shown in FIG. 7, the outer cylinder portion 252 has a protrusion 252b formed on the outer peripheral surface, and the protrusion 252b is arranged on the outer periphery of the outer cylinder portion 252 to form a spiral guide portion 28a. 28 is engaged. In FIG. 4B, which shows the rotating cam 28, the rotating cam 28 is shown in an exploded manner for the convenience of understanding. 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 (shutter closed state), and toner does not leak to the outside. On the other hand, when the toner supply pipe 25 moves downward, the outer cylinder portion 252 is rotated by the engagement between the protrusion 252b and the spiral guide portion 28a of the rotating cam 28, and the tip of the toner supply pipe 25 is the developing device 16. When the toner enters the supply position and enters the supply position, the opening 251a of the inner cylinder 251 and the opening 252a of the outer cylinder 252 coincide (shutter open state), and the internal toner is developed from the openings 251a and 252a. It is supplied to the inside of the vessel 16.

[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 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 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.

[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. 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.

[Toner supply operation]
When supplying the 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 of the color to be supplied with toner is moved downward to be positioned at the supply position. That is, when the motor is driven, the pinion gear 33 rotates through the clutch 33a and the gear train, whereby power is transmitted to the rack 32 and the toner supply pipe 25 is moved downward. Further, 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. As the toner supply pipe 25 of the color to be supplied with toner moves downward, the outer cylinder 252 constituting the toner supply pipe 25 rotates with respect to the inner cylinder 251, and the tip of the toner supply pipe 25 is developed. At the time of entering the inside of the vessel 16, the opening 252 a of the outer cylinder part 252 and the opening 251 a of the inner cylinder part 251 coincide. That is, the shutter mechanism is opened.

  Here, when the toner supply pipe 25 is lowered as described above, the solenoid 74 is not energized. Therefore, no attracting force is applied to the plunger 74a of the solenoid 74, and the lever 77 is rotated clockwise around the fulcrum by the coil spring 81, and is stopped with the plunger 74a protruding to the maximum extent (FIG. 11 (a)). In this state, the locking plate 73 is urged toward the solenoid 74 by the coil spring 75 and is in contact with the lever 77 in a state as shown in FIG. In this case, the locking projection 71 that descends together with the toner supply pipe 25 passes through the square hole 72 of the locking plate 73. This state is schematically shown in FIG.

  When the toner supply pipe 25 is positioned at the toner supply position, the solenoid 74 is energized, and the plunger 74a is retracted. Then, the lever 77 in the posture as shown in FIG. 11 (a) is rotated counterclockwise around the fulcrum and assumes the posture as shown in FIG. 11 (b). As the lever 77 rotates, the positional relationship between the lever 77 and the locking plate 73 changes from the state shown in FIG. 12A to the state shown in FIG. That is, the rotation of the lever 77 pushes the locking plate 73 away from the solenoid 74 while the inclined surface 77c of the lever 77 contacts the bent portions 73b and 73a of the locking plate 73. Therefore, the locking plate 73 moves toward the coil spring 75 against the urging force of the coil spring 75. This state is schematically shown in FIG. Here, the locking plate 73 is locked to the locking projection 71, and the toner supply pipe 25 is prohibited from moving upward. Therefore, in this state, even if the motor of the drive mechanism 27 and the clutch 33a are turned off, the toner supply pipe 25 is maintained at the toner supply position. Since the bent portions 73a and 73b are formed in the contact portion of the locking plate 73 with the lever 77, both slide smoothly.

  When the toner supply pipe 25 is located at the supply position, the toner supply pipe 25 blocks the laser light 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 energization to the solenoid 74 is stopped. Then, the plunger 74a is in a free state, and the lever 77 is rotated clockwise by the urging force of the coil spring 81 to the state shown in FIG. As a result, the lever 77 moves to the side away from the locking plate 73, so that the locking plate 73 is moved to the solenoid 74 side by the coil spring 75, as shown in FIG. It becomes a state like this. In this case, as shown in FIG. 13A, the locking protrusion 71 of the toner supply pipe 25 and the square hole 72 of the locking plate 73 coincide with each other, and the upward movement of the toner supply pipe 25 is allowed. It becomes a state.

  In this state, the motor rotates reversely, the clutch 33a enters the power transmission state, and the pinion gear 33 rotates reversely. As a result, 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.

[When power is cut off]
When the power supply is cut off when the toner supply pipe 25 is located at the toner supply position, the energization to the solenoid 74 is also turned off, so that the plunger 74a is in a free state. In this case, as in the case where the toner supply is completed, the lever 77 is brought into the state shown in FIG. 11A by the coil spring 81, and the locking plate 73 is moved to the solenoid 74 side and shown in FIG. It will be in the state shown. In the power cut-off state, the toner supply pipe 25 cannot be moved upward to the retracted position by the drive mechanism 27, but the toner supply pipe 25 is moved to the retracted position by the torsion spring 70 fixed to the frame 76. 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.

[Effect of this embodiment]
In the present embodiment, even if the power supply is interrupted when the toner supply pipe 25 is located at the toner supply position, the rotary developing device 3 rotates in this state and the toner supply pipe 25 and the developing device 16 are damaged. Can be prevented. Further, when the state where the toner supply pipe 25 enters the developing device 16 continues for a long time, the slit 18a of the elastic member disposed in the toner supply unit 18 is cured, and the rotary developing device 3 rotates while the slit 18a is cured. Therefore, it is possible to prevent toner leakage.

[Other Embodiments]
In the above embodiment, the band-shaped locking plate 73 having a plurality of square holes 72 is used as the second locking member. However, the present invention is not limited to this, and the locking protrusion 71 and the locking protrusion 71 are engaged with each other. Protrusions that can be stopped may be provided, and the columnar member may be rotated so that the engaging protrusions 71 and the protrusions are engaged to restrict the upward movement of the toner supply pipe 25 in the vertical direction. In the above embodiment, the torsion spring 70 is used to move the toner supply pipe 25 to the retracted position when the power is cut off. However, the present invention is not limited to this, and a coil spring or the like may be used.

1 is a schematic configuration diagram of a color printer according to an embodiment of the present invention. External perspective view of developer 2 is a detailed cross-sectional configuration diagram of a toner supply device. FIG. 3 is an external view of a toner supply pipe driver mechanism. The block diagram of the toner supply pipe front-end | tip. FIG. 3 is an external view of a toner supply pipe and a toner transport pipe. FIG. 3 is an external view of a toner supply pipe. The frame side block diagram of the color printer of a position holding mechanism. FIG. 3 is a detailed view of a solenoid fixed to a frame of a color printer in a power transmission state. FIG. 3 is a detailed view of a solenoid fixed to a color printer frame in a power cut-off state. The schematic diagram which shows the relationship between the solenoid 74, the lever 77, and the coil spring 81. FIG. The figure which shows the operation | movement at the time of the lever 77 and the latching plate 73 contacting each other. The figure which shows the operation | movement at the time of the latching protrusion 71 and the latching plate 73 latching mutually.

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 71 Locking protrusion 72 Square hole 73 Locking plate 80 Position holding mechanism 90 Retraction mechanism

Claims (7)

A plurality of container main bodies each having a developing roller corresponding to each color;
A plurality of toner supply members each having a toner supply port for supplying toner to each of the plurality of container bodies;
The toner supply member moves the toner supply member so that the toner supply port can take a toner supply position where the toner supply port is located inside the container body and a retracted position where the toner supply member is located outside the container body. A drive mechanism for
A position holding mechanism for restricting movement of the toner supply member in a state where the toner supply member is located at the toner supply position;
When power is interrupted while the toner supply member is in the toner supply position, the restriction of movement of the toner supply member by the position holding mechanism is released, and the toner supply member is positioned in the retracted position. A evacuation mechanism,
Development unit equipped with. The position holding mechanism includes a first locking portion fixed to the toner supply member, and a second locking member locked to the first locking portion.
The developing unit according to claim 1. The retracting mechanism includes: a second locking member driving device that moves the second locking member to release the locking between the first locking portion and the second locking member; and the toner supply member. An urging member for urging the retracted position;
The developing unit according to claim 1. The position holding mechanism further includes a second locking member moving member that moves the second locking member so that the first locking portion is locked with the second locking member.
The developing unit according to claim 2 or 3. The second locking member driving device is a biasing member;
The developing unit according to claim 3. A shutter that opens the toner supply port when the toner supply member is positioned at the toner supply position, and closes the toner supply port when the toner supply member is positioned at the retracted position. Further equipped with a mechanism,
The developing unit according to claim 1. The container body includes an elastic member having a slit that passes when the toner supply member moves between the retracted position and the toner supply position.
The developing unit according to claim 1.

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