JP2007004058A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus having a mechanism capable of managing an amount of toner to be supplied to a developing unit with sufficient accuracy by simple structure. <P>SOLUTION: The image forming apparatus has an image formation part, a fixing unit, a paper sheet feeding part and a toner supply part. The image formation part forms a toner image and transfers the formed toner image to paper sheet. The fixing unit is the one for fixing the toner image transferred on the paper sheet by the image forming part. The paper sheet feeding part is a part for feeding the paper sheet to the image formation part and the fixing unit. The toner supply part has a toner supply pipe 25 which supplies toner to the image formation part, a toner storage part 5 which stores the toner inside and a toner conveyance pipe 26 which has coil spring 31 inside and conveys the toner in the toner storage part 5 to the toner supply pipe 25. The toner conveyance pipe 26 has a part lower than the downstream side of the toner conveyance direction on the upstream side of the toner conveyance direction. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus, and more particularly, to an image forming apparatus including a developing unit that is supplied with toner from the outside.

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

Therefore, in order to reduce the size of the developing unit, a developing unit that supplies toner from the outside has been proposed. As a developing unit that supplies toner from the outside, there is one described in Japanese Patent Laid-Open No. 2001-134045. This publication describes an image forming apparatus adopting a rotary developing system, in which a shutter mechanism is opened while a joint portion of a rotating rotary developer slides, and a toner container and a developing device are developed at a specific stop position. It is configured to communicate with the vessel. When the toner container and the rotating rotary developer communicate with each other, the toner in the toner container is supplied to the developer by spontaneously dropping.
JP 2001-134045 A

  Since the conventional developing unit supplies toner to the developing device by naturally dropping the toner in the toner containing portion, when supplying toner in the toner containing portion to the developing device, it is not possible to accurately manage the toner supply amount. Have difficulty.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus having a mechanism capable of accurately managing the amount of toner supplied to a developing device with a simple structure.

  An image forming apparatus according to a first aspect includes an image forming unit, a paper transport unit, and a toner supply unit. The image forming unit is a part that forms a toner image and transfers the formed toner image to a sheet. The paper transport unit is a part for transporting paper to the image forming unit. The toner supply unit includes a toner supply member that supplies toner to the image forming unit, a toner storage unit that stores toner therein, and a toner that has a toner transport member therein and that transports the toner in the toner storage unit to the toner supply member And a transport unit. The toner transport pipe has a lower portion on the upstream side in the toner transport direction than on the downstream side in the toner transport direction.

  In this image forming apparatus, when toner is supplied, the toner in the toner storage unit is conveyed to the toner supply member via the toner conveyance unit. Here, the toner in the toner storage portion passes through a lower portion on the upstream side in the toner conveyance direction of the toner conveyance portion than the downstream side in the toner conveyance direction, and is conveyed to the toner supply member. In this case, since the downstream side in the toner transport direction is higher than the upstream side in the toner transport direction, the toner is unlikely to fall freely and is transported by the transport force of the toner transport member.

  Here, since the free fall of the toner is suppressed, the amount of toner supplied to the toner supply member of the toner conveying member can be managed with higher accuracy than in the past.

  An image forming apparatus according to a second aspect is the image forming apparatus according to the first aspect, wherein the connecting portion between the toner conveying portion and the toner accommodating portion is more than the connecting portion between the toner conveying portion and the toner supply member. Located in a low position.

  An image forming apparatus according to a third aspect is the image forming apparatus according to the first or second aspect, wherein the toner conveyance amount of the toner conveyance unit is smaller than the toner supply amount of the toner supply member.

  Here, since the amount of toner supplied to the image forming unit by the toner supply member is larger than the amount of toner conveyed to the toner supply member by the toner conveyance unit, the toner conveyed by the toner conveyance unit is contained in the toner supply member. It becomes difficult to clog. Therefore, the toner supply amount can be managed with higher accuracy.

  An image forming apparatus according to a fourth aspect is the image forming apparatus according to any one of the first to third aspects, wherein a toner supply amount from the toner containing portion to the toner conveying portion is a toner conveying amount of the toner conveying portion. Less than.

  Here, since the amount of toner conveyed to the toner supply member by the toner conveying unit is larger than the amount of toner supplied from the toner accommodating unit to the toner conveying unit, the toner supplied from the toner accommodating unit is not contained in the toner conveying unit. It becomes difficult to clog. For this reason, the toner conveyance amount can be managed with higher accuracy.

  An image forming apparatus according to a fifth aspect is the image forming apparatus according to any one of the first to fourth aspects, wherein the connecting portion between the toner supply member and the toner conveyance portion includes a toner supply member, a toner conveyance portion, and the like. It is arrange | positioned in the position higher than the upstream of the connection part vicinity.

  Here, the present invention can be obtained with a simple configuration.

  In the present invention, it is possible to accurately manage the amount of toner supplied from the toner storage portion into the image forming portion.

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

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

  The color printer 1 includes a photosensitive drum 2, a rotary developing device 3, a laser unit 4, a toner container 5, a toner supply device 6, an intermediate transfer belt 7, a secondary transfer roller 8, and a fixing device 9. And have. Here, an image forming unit is configured by the photosensitive drum 2, the rotary developing device 3, the laser unit 4, the intermediate transfer belt 7, and the secondary transfer roller 8.

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

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

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

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

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

[Toner supply device]
As shown in FIGS. 2 and 3, 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, above the photosensitive drum 2. These are disposed in a space between the laser unit 4 and the toner storage portion 5. The toner supply device 6 includes four transport pipes that connect four toner supply pipes 25 that can move in the vertical direction and a toner supply pipe 25 that corresponds to a portion of the toner storage unit 5 that stores toner of each color. 26 and a drive mechanism 27 for moving each toner supply pipe 25 up and down.

  The toner supply pipe 25 is long in the vertical direction, and has an upper end inclined toward the front side of the apparatus and a lower end inclined toward the back side of the apparatus. The tip of the toner supply pipe 25 has a tapered shape, and when the toner supply pipe 25 moves downward, the tip can enter the inside through the toner supply portion of the developing device 16. A toner conveying screw 30 for conveying the toner is rotatably provided inside the toner supply pipe 25.

  The toner transport pipe 26 is a member for transporting the toner supplied from the toner container 5 to the toner supply pipe 25, and is flexible so that it can move following the vertical movement of the toner supply pipe 25. It is the cylindrical member which has. As shown in FIG. 2, the toner transport pipe 26 includes a first connection portion 26 a that connects the toner transport pipe 26 and the toner storage portion 5, and a second connection portion that connects the toner transport pipe 26 and the toner supply pipe 25. 26b, and a toner conveying portion 26c that is located between the first connecting portion 26a and the second connecting portion 26b and conveys toner. As shown in FIG. 2, even when the toner supply pipe 25 is located on the lowermost side, the second connection part 26b is located on the upper side compared to the first connection part 26a. The toner conveying portion 26c is a member that conveys toner from the first connecting portion 26a to the second connecting portion 26b, and is inclined so as to incline upward from the first connecting portion 26a to the second connecting portion 26b. . A coil spring 31 is disposed inside the toner transport pipe 26 and is rotated by a drive mechanism (not shown), whereby the toner is transported through the transport pipe 26 to the toner supply pipe 25 side. .

  As shown in FIG. 3, the drive mechanism 27 has a rack 32 provided along the axial direction on the outer periphery of the toner supply pipe 25, and a pinion gear 33 that meshes with the rack 32. The pinion gear 33 is rotatably supported by the frame of the apparatus and is driven by a motor or the like (not shown). With this drive mechanism 27, the toner supply pipe 25 can take an upper retracted position and a supply position where the tip portion enters the inside of the developing device 16 at the lower side.

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

  A belt cleaning device 40 for cleaning the intermediate 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 intermediate transfer belt 7, and a cleaning roller disposed above the fur brush 41 so as to contact the fur brush 41. 42, a blade 43 disposed so that the tip thereof contacts the surface of the cleaning roller 42, and a collection spiral 44 disposed side by side below the blade 43.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[Toner supply operation]
When supplying toner to the developing device 16, the toner supply pipe 25 is moved downward to be positioned at the supply position. That is, when a motor (not shown) is driven, the pinion gear 33 rotates through the gear, and the toner supply pipe 25 to which the rack 32 is fixed moves downward. On the other hand, toner is supplied from the toner storage unit 5 to the toner transport pipe 26. The toner is conveyed from the first connection portion 26a to the second connection portion 26b via the toner conveyance portion 26c by a coil spring 31 in the toner conveyance pipe 26. Here, since the toner conveying portion 26c is inclined so as to incline upward from the first connecting portion 26a to the second connecting portion 26b, the toner is not easily dropped and is conveyed by the conveying force of the coil spring 31. . For this reason, the amount of toner supplied to the developing device 16 can be accurately managed. Note that the amount of toner supplied from the toner container 5 to the toner transport pipe 26 is smaller than the amount of toner that can be transported to the toner supply pipe 25 by the toner transport pipe 26, and the toner that can be transported to the toner supply pipe 25 by the toner transport pipe 26. This amount is set to be smaller than the amount of toner that can be supplied to the developing device 16 by the toner supply pipe 25. Accordingly, the toner is not easily clogged in the toner transport pipe 26 and the toner supply pipe 25, and the management accuracy of the toner supply amount due to the clogging of the toner is not easily lowered. Then, after the toner is conveyed to the toner supply pipe 25 side by the toner conveyance pipe 26, the tip of the toner supply pipe 25 passes through the toner supply port and enters the inside of the developing device 16. At the time of the downward movement of the toner supply pipe 25, the outer cylinder portion constituting the toner supply pipe 25 rotates with respect to the inner cylinder portion, and when the tip of the toner supply pipe 25 enters the inside of the developing device 16, The opening of the outer cylinder part coincides with the opening of the inner cylinder part. That is, the shutter mechanism is opened, and the toner inside the toner supply pipe 25 is supplied into the developing device 16. Here, since toner does not remain in the toner supply pipe 25 at the end of the toner supply operation, toner aggregation and toner clogging due to toner collecting at the tip of the toner supply pipe 25 and toner drop from the shutter mechanism are prevented. Can do.

[Other Embodiments]
In the embodiment described above, the whole is inclined upward from the first connection portion 26a to the second connection portion 26b, but at least the second connection portion 26b is disposed at a position higher than the upstream side in the vicinity of the second connection portion 26b. It only has to be. Moreover, although the coil spring was used in the said embodiment, the flexible spiral shape | molded with the elastomer may be sufficient.

1 is a schematic configuration diagram of a color printer according to an embodiment of the present invention. 2 is a detailed cross-sectional configuration diagram of a toner supply device. FIG. 3 is an external view of a toner supply pipe driver mechanism.

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

Claims (5)

An image forming unit that forms a toner image and transfers the formed toner image to paper;
A paper transport unit for transporting paper to the image forming unit;
A toner supply unit for supplying toner to the image forming unit,
The toner supply unit includes a toner supply member that supplies toner to the image forming unit, a toner storage unit that stores toner therein, and a toner conveyance member inside, and the toner in the toner storage unit is transferred to the toner supply member And a toner transport section for transporting to the
The toner conveying portion has a lower portion on the upstream side in the toner conveying direction than on the downstream side in the toner conveying direction;
Image forming apparatus. A connecting portion between the toner conveying portion and the toner containing portion is disposed at a position lower than a connecting portion between the toner conveying portion and the toner supply member;
The image forming apparatus according to claim 1. A toner conveyance amount of the toner conveyance unit is smaller than a toner supply amount of the toner supply member;
The image forming apparatus according to claim 1. The toner supply amount from the toner storage unit to the toner conveyance unit is smaller than the toner conveyance amount of the toner conveyance unit.
The image forming apparatus according to claim 1. The connecting portion between the toner supply member and the toner conveying portion is disposed at a position higher than the upstream side in the vicinity of the connecting portion between the toner supplying member and the toner conveying portion.
The image forming apparatus according to claim 1.

Images