JP2011221351A - Developing device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent density difference from occurring in an image in the width direction of a sheet.SOLUTION: A developing device includes: a toner cartridge 22 for containing toner therein; a toner-holding chamber 19 for holding toner supplied via a toner supply port 14 provided in the central part of the toner cartridge 22; a toner-amount detection bar 15 by which stirring operation of toner is performed below the toner supply port 14 in the toner holding chamber 19: and a shutter 61 which shields the toner supply port 14 and is provided so as to be openable and closable. Then, the shutter 61 is driven by a shutter drive bar 63 rotated by interlocking with the stirring operation of the toner amount detection bar 15 to perform opening and closing operations.

Description

  The present invention relates to a developing device and an image forming apparatus such as an electrophotographic printer and a copying machine.

  2. Description of the Related Art Conventionally, in image forming apparatuses such as printers, copiers, facsimile machines, and multifunction machines, the surface of a photosensitive drum is charged by a charging roller and exposed by an LED head to form an electrostatic latent image. The toner thinned on the developing roller is electrostatically attached to the toner to form a toner image, and the toner image is transferred to a sheet by a transfer roller to form an image, that is, print. ing. Further, toner remaining on the photosensitive drum after the transfer is removed by a cleaning device. These photosensitive drums, charging rollers, developing rollers and the like constitute a developing device. The sheet on which the toner image has been transferred is sent to a fixing device, where the toner image is fixed on the sheet.

  By the way, in the printer, the developing device includes a developing device main body and a toner cartridge that is detachably disposed with respect to the developing device main body, and the toner cartridge is connected to the developing device main body via a toner supply port. Toner is supplied. However, when the toner cartridge is removed from the developing device main body, the toner adhering to the periphery of the toner supply port may fall to the surroundings and stain the inside of the printer.

  As a countermeasure against this, for example, there is a technique in which the toner supply port is formed small at the center in the longitudinal direction of the toner cartridge as disclosed in Japanese Patent Laid-Open No. 2006-220877 (Patent Document 1). In the developing device of Patent Document 1, when the printer is used after the toner cartridge is mounted, the toner is stirred by rotating the stirring bar in the developing device that receives the supply of toner from the toner cartridge. The stirring bar is arranged at the lower part of the toner cartridge. Therefore, the toner may be pushed back from the developing device to the toner cartridge by the rotation operation of the stirring bar in the developing device. On the other hand, if the supply port of the toner cartridge is opened over the entire length of the cartridge, the force with which the toner is pushed back by the operation of the stirring bar in the developing device becomes weak in the vicinity where the toner is low. It does n’t matter.

JP 2006-220877 A

  However, when the supply port is formed only at the center in the longitudinal direction of the toner cartridge as in the developing device of Patent Document 1, there are the following problems. That is, for example, if the toner consumption is large at a position away from the supply port in the longitudinal direction, the amount of toner is reduced. On the other hand, if sufficient toner still remains near the central supply port, The force with which the toner is pushed back makes it difficult for the toner to be supplied from the central supply port. Then, the remaining amount of toner in the developing device is biased in the longitudinal direction of the toner cartridge, causing a problem that a density difference occurs in the printed image in the width direction of the recording medium. Furthermore, there is a problem that a decrease in the remaining amount of toner is detected even though the toner remains in the toner cartridge.

  The problem to be solved by the present invention is that when the toner cartridge is removed from the developing device main body, the inside of the printer is not stained, and further, a density difference is generated in the image in the width direction of the recording medium. It is an object of the present invention to provide an image forming apparatus capable of preventing the toner in the toner cartridge from being used up.

  In order to solve the above problems, a developing device according to the present invention holds a developer containing container for containing a developer and a developer supplied via a developer supply port provided in a central portion of the developer containing container. A developer holding chamber, a stirring member for stirring the developer below the developer supply port in the developer holding chamber, and a shield provided to be able to open and close the developer supply port. And a shielding member that opens and closes in conjunction with the stirring operation of the stirring member.

  According to the present invention having the above-described configuration, an image forming apparatus that does not contaminate the inside of the printer when the toner cartridge is removed from the developing device main body is provided, and at the same time, the density difference in the image in the width direction of the recording medium It is possible to provide an image forming apparatus that can prevent the occurrence of toner and can use up the toner in the toner cartridge.

It is sectional drawing of the image development apparatus regarding 1st Embodiment. It is a perspective view which shows the inside of the developing device regarding 1st Embodiment. 1 is a schematic diagram of a printer according to a first embodiment. It is explanatory drawing which shows shutter drive operation | movement. It is explanatory drawing which similarly shows shutter drive operation | movement. It is sectional drawing of the image development apparatus regarding 2nd Embodiment. It is explanatory drawing which shows operation | movement of the shutter regarding 2nd Embodiment. It is explanatory drawing which shows the effect | action of the shutter regarding 2nd Embodiment.

<First Embodiment>
Hereinafter, a first embodiment of the present invention will be described in detail with reference to the drawings. In this case, a case where an image is formed, that is, printed by a color printer as an image forming apparatus will be described.

  FIG. 3 is a schematic diagram of the printer according to the first embodiment. As shown in FIG. 3, the electrophotographic printer 10 includes a lower cover 41 as a lower casing, and an upper casing that is swingable about a support shaft 42 with respect to the lower cover 41 and that can be opened and closed. A stacker 44 that has an upper cover 43 as a body and from which paper as a printed recording medium is discharged is formed on the upper cover 43.

  A paper feed cassette 50 serving as a medium storage unit for storing paper is disposed in the lower portion of the lower cover 41. A feeding roller 51 serving as a medium supply unit is disposed at the front end of the paper feed cassette 50, and the feeding roller 51 feeds and supplies the sheet to the medium conveyance path 49. The medium conveyance path 49 has an S shape, and is provided with paper feed rollers 45 to 48 and a belt unit 53 as a medium conveyance device. The belt unit 53 includes a driving roller R1 as a first roller, a driven roller R2 as a second roller, and a conveying belt 52 as a conveying member stretched between the driving roller R1 and the driven roller R2. Have

  In the belt unit 53, the transport belt 52 is caused to travel, and the paper is transported by the transport belt 52 accordingly. Further, the paper is composed of a plurality of developing devices (image drum units) 55Bk, 55Y, 55M, and 55C as image forming units for forming images of black, yellow, magenta, and cyan, and transfer rollers 57 as transfer devices. Pass between.

  The developing devices 55Bk, 55Y, 55M, and 55C are, as will be described later, a photosensitive drum 12 as an image carrier, a charging roller 13 as a charging device disposed around the photosensitive drum 12, and a developer as a developer. A developing roller 16 as a developer carrying member for holding toner is provided. Then, a recording head 56 as an exposure device adjacent to each developing device 55Bk, 55Y, 55M, 55C is disposed, facing each photosensitive drum 12 of each developing device 55Bk, 55Y, 55M, 55C, and each transfer unit. A roller 57 is provided.

  In each of the developing devices 55Bk, 55Y, 55M, and 55C, the photosensitive drum 12 is rotated in a predetermined direction by driving a drum motor (not shown) as a driving unit for image formation. Further, as the photosensitive drum 12 rotates, the surface of the photosensitive drum 12 is uniformly and uniformly charged by the charging roller 13 and is exposed by the recording head 56 to form an electrostatic latent image. . The toner on the developing roller 16 is electrostatically attached to the electrostatic latent image to form a toner image as a developer image.

  Then, when the sheet conveyed by the sheet feeding rollers 45 and 46 and fed to the medium conveying path 49 passes between the developing devices 55Bk, 55Y, 55M, and 55C and the transfer rollers 57, the transfer rollers 57 sequentially transfers the toner images as the developer images of the respective colors formed in the developing devices 55Bk, 55Y, 55M, and 55C onto the paper, thereby forming a color toner image.

  Subsequently, the paper is sent to a fixing device 54 as a fixing device, and a color toner image is fixed on the paper in the fixing device 54 to form a color image. The paper discharged from the fixing device 54 is conveyed by the paper feed roller 47 and then discharged to the stacker 44 by the discharge roller 48.

  Next, the developing devices 55Bk, 55Y, 55M, and 55C will be described. Since the developing devices 55Bk, 55Y, 55M, and 55C have the same structure, the developing device 55Bk will be described. FIG. 1 is a cross-sectional view of the developing device according to the first embodiment.

  The developing device 55Bk includes a photosensitive drum 12 as an image carrier on which an electrostatic latent image is formed, a charging roller 13 that charges the photosensitive drum 12 while rotating while being in pressure contact with the photosensitive drum 12, and the photosensitive drum. A developing roller 16 for supplying toner to the body drum 12, a developing blade 17 as a regulating member for regulating the amount of toner on the developing roller 16, and a supplying roller as a developer supplying member for supplying toner to the developing roller 16 18 and a cleaning unit 21 for removing the toner remaining on the photosensitive drum 12. Further, the developing device 55Bk includes a developing roller 16, a developing blade 17 and a supply roller 18, and a toner holding chamber 19 as a developer holding chamber that holds and holds the toner supplied from the toner cartridge 22. Prepare.

  The toner cartridge 22 as a developer container is detachably disposed on the main body of the developing device 55Bk, and is formed at the bottom of the toner cartridge 22 and at the top of the toner holding chamber 19. The toner is supplied to the toner holding chamber 19 from the toner supply port 14 as the agent supply port. A stirring bar 29 as a first stirring member for stirring the toner and supplying it to the toner holding chamber 19 is disposed in the toner cartridge 22.

  In the toner holding chamber 19, stirring members 23 and 24 as second and third stirring members for stirring the toner in the toner holding chamber 19 are adjacent to the supply roller 18 and are mutually connected. They are arranged in parallel. Further, a toner amount detection bar 15 that functions as a fourth stirring member for stirring the inside of the toner holding chamber 19 and a function for detecting the remaining amount of developer is disposed above the stirring members 23 and 24. The toner amount detection bar 15 performs a toner stirring operation below the toner supply port 14. Further, below the toner supply port 14, as a developer conveying member for conveying the toner supplied from the toner supply port 14 in the width direction of the electrophotographic printer 10, that is, in both longitudinal directions of the toner holding chamber 19. The spiral 26 is disposed along the longitudinal direction of the toner holding chamber 19.

  The toner supply port 14 of the toner holding chamber 19 is provided with a shutter 61 as a shielding member that shields the toner supply port 14 and reciprocates in the direction of arrow G by a guide (not shown). A link 62 is connected to the shutter 61 and is connected to a shutter drive bar 63 provided in parallel with the toner amount detection bar 15.

  FIG. 2 is a perspective view showing the inside of the developing device according to the first embodiment. The agitating members 23 and 24 are not shown. In the drawing, a spiral 26, a toner amount detection bar 15, and a shutter drive bar 63 are provided above the developing roller 16 and the supply roller 18 and below the toner supply port 14. The toner supply port 14 is provided at the center in the longitudinal direction of the toner cartridge 22, that is, at the center in the longitudinal direction of the toner holding chamber 19.

  Since the spiral 26 forms an auger in opposite winding directions from the center to both ends in the longitudinal direction, when the spiral 26 is rotated in the direction of arrow D, the toner that has descended from the toner supply port 14 is moved to the arrows E and F. It is sorted and conveyed in the direction. As described above, the toner amount detection bar 15 has both a toner stirring function and a developer remaining amount detection function. The toner amount detection bar 15 is formed in a crank shape, and is rotated by driving a toner amount detection bar drive gear 66 provided at one end. The rotation of the drive portion of the toner amount detection bar 15 rotates the entire toner amount detection bar 15 with the crank portion as a radius, and detects the remaining amount of toner while stirring the toner in the toner holding chamber 19.

  The shutter drive bar 63 is driven by a shutter drive gear 64, and power is transmitted from the toner amount detection bar drive gear 66 to the shutter drive gear 64 via an idle gear 65. The shutter drive bar 63 is formed in a crank shape at the center, a link 62 is connected from the crank portion, and the link 62 is connected to the shutter 61. The shutter 61 is provided below the toner supply port 14, shields the toner supply port 14, and moves in the direction of arrow G through the link 62 by the rotation of the shutter drive bar 63 to open and close the toner supply port 14. Therefore, the opening / closing operation of the shutter 61 is interlocked with the stirring operation of the toner amount detection bar 15.

  Next, the operation of the electrophotographic printer 10 having the above configuration will be described. First, the surface of the photosensitive drum 12 uniformly charged by the charging device 13 is exposed by the recording head 56 to form an electrostatic latent image. The electrostatic latent image on the photosensitive drum 12 is developed into toner image by the toner supplied by the developing roller 16. The toner image on the photosensitive drum 12 is transferred onto transfer paper by each transfer roller 57. On the other hand, the toner remaining on the photosensitive drum 12 is collected by the cleaning device 21. Toner is supplied from the toner holding chamber 19 to the developing roller 16 by the toner supply roller 18, and the toner supplied onto the developing roller 16 is thinned by the developing blade 17 and charged to a predetermined charge.

  Here, when the use of the new developing device 55Bk is started and when the toner cartridge 22 is replaced, the toner is supplied to the toner holding chamber 19 through the toner supply port 14 of the toner cartridge 22. Since the spiral 26 is rotated in the direction of arrow D, the toner is distributed in the directions of arrows E and F and conveyed.

  When the toner holding chamber 19 is filled with toner, the toner in the toner cartridge 22 is not supplied, and thereafter, the toner is sequentially supplied from the toner supply port 14 as the toner is consumed.

  The toner supplied to the toner holding chamber 19 is agitated by the rotation of the toner amount detection bar 15 and the agitating members 23 and 24 so that the agglomeration condition and the charging condition become uniform. Further, as the toner amount detection bar 15 is rotated by driving the toner amount detection bar drive gear 66, the shutter drive gear 64 is driven via the idle gear 65, so that the shutter drive bar 63 rotates the toner amount detection bar 15. It rotates in the same rotation direction I as the direction H. As the shutter drive bar 63 rotates, the shutter 61 is reciprocated in the direction of arrow G via the link 62, and the shutter 61 operates to open and close the toner supply port 14.

  4 and 5 are explanatory diagrams showing the shutter driving operation. FIG. 4 shows the positional relationship between the shutter 61 and the toner amount detection bar 15 when the toner amount detection bar 15 operates from the bottom to the top. FIG. 5 shows the positional relationship between the shutter 61 and the toner amount detection bar 15 when the toner amount detection bar 15 operates from the top to the bottom after the positional relationship shown in FIG. Since the rotation speed of the shutter drive bar 63 is set to be the same as that of the toner amount detection bar 15, when the toner amount detection bar 15 is at a predetermined position in the counterclockwise direction, the shutter drive bar 63 rotates in the counterclockwise direction. The position is also a predetermined position, and the shutter 61 is also a predetermined position in the arrow G direction.

  As shown in FIG. 4A, when the rotational position of the toner amount detection bar 15 is downward, the shutter drive bar 63 is also downward, and as a result, the shutter 61 moves from left to right, and the toner The supply port 14 is moving from an open state to a closed state. Next, as shown in FIG. 4B, as the toner amount detection bar 15 rotates in the counterclockwise arrow H direction, the shutter drive bar 63 also rotates in the same counterclockwise arrow I direction. As a result, the shutter 61 moves to the right in conjunction with the stirring operation of the toner amount detection bar 15, and the toner supply port 14 is gradually closed.

  Thereafter, the toner amount detection bar 15 further rotates, and when the toner amount detection bar 15 comes near the 3 o'clock position in the counterclockwise direction as shown in FIGS. Is when the toner heads toward the toner supply port 14. At this time, the toner flow toward the toner supply port 14 by the toner amount detection bar 15 is in the direction of arrow J.

  At this time, the shutter drive bar 63 is also near the 3 o'clock position in the counterclockwise direction, and as a result, the shutter 61 moves to the right in conjunction with the stirring operation of the toner amount detection bar 15, and the toner supply port 14 is It is in the most closed state. Thus, the toner flow is blocked by the shutter 61 and dispersed in the directions of the arrows L and M, so that the toner does not flow backward into the toner cartridge 22. Note that the shutter 61 does not need to completely close the toner supply port 14 as long as the shutter 14 moves to block the toner flow in the direction of arrow J and to prevent the backflow of toner.

  On the other hand, as shown in FIG. 5A, when the rotation position of the toner amount detection bar 15 is upward, the shutter drive bar 63 is also upward, and as a result, the shutter 61 moves from the right to the left. The toner supply port 14 is moving from the closed state to the open state. Next, as shown in FIG. 5B, as the toner amount detection bar 15 rotates in the counterclockwise arrow H direction, the shutter drive bar 63 also rotates in the same arrow I direction. As a result, the shutter 61 moves to the left in conjunction with the stirring operation of the toner amount detection bar 15, and the supply port 14 gradually opens.

  Thereafter, as shown in FIGS. 5C and 5D, when the toner amount detection bar 15 further rotates and comes near the 9 o'clock position in the counterclockwise direction, the toner amount detection bar 15 passes through the toner supply port 14. It ’s time to leave. At this time, the flow of toner from the toner supply port 14 is in the direction of arrow K.

  At this time, the shutter drive bar 63 is also near the 9 o'clock position in the counterclockwise direction. As a result, the shutter 61 moves to the left in conjunction with the stirring operation of the toner amount detection bar 15, and the toner supply port 14 is It will be in the most open state.

  Considering the case where the toner supply port is formed only at the central portion in the longitudinal direction of the toner cartridge as in the developing device of Patent Document 1 described above and the shutter 61 is not provided, FIG. When the toner amount detection bar operates from bottom to top as shown in FIG. 4A to FIG. 4D, a toner flow toward the toner supply port 14 occurs in the direction of arrow J. Further, when the toner amount detection bar 15 operates from the top to the bottom as shown in FIGS. 5A to 5D of the present embodiment, the toner is indicated in the direction of the arrow K by the weight of the toner. A toner flow from the supply port 14 occurs. In normal use, the flow rates of the toner flowing in the direction of the arrow J and the toner flowing in the direction of the arrow K are almost the same, and as a result, the toner does not flow backward into the toner cartridge 22.

  However, as printing progresses and the degree of toner aggregation increases, the flow in the free fall arrow K direction becomes slower than the forced flow in the arrow J direction, and the toner seems to flow backward into the toner cartridge 22. As a result, the toner is not supplied from the toner cartridge 22 to the toner holding chamber 19. In particular, when a large amount of toner is consumed at a position away from the toner supply port 14 such as both ends of the image, the toner is biased in the longitudinal direction of the toner holding chamber 19 and a density difference occurs. In addition, when a large amount of toner remains in the toner cartridge 22, the toner at both ends of the toner holding chamber 19 is decreased, and a decrease in the toner amount may be detected.

  In contrast, in the present embodiment, since the shutter 61 is disposed at the toner supply port 14, when the toner amount detection bar 15 moves from the bottom to the toner supply port 14, the shutter 61 is connected to the toner supply port 14. Therefore, the toner flow in the direction of arrow J is dispersed in the directions of arrows L and M, so that the toner does not flow backward into the toner cartridge 22. Further, since the agitation state is also improved, there is no unevenness of toner in the toner holding chamber 19, the occurrence of density difference can be suppressed, and the toner remaining in the toner cartridge 22 can be reduced.

<Second Embodiment>
Next, a second embodiment of the present invention will be described. In addition, about the thing which has the same structure as 1st Embodiment, the description is abbreviate | omitted by providing the same code | symbol, and the effect of the same embodiment is used about the effect of the invention by having the same structure. .

  FIG. 6 is a cross-sectional view of the developing device according to the second embodiment. A shutter 71 as a shielding member for shielding the toner supply port is provided near the toner supply port 14 of the toner holding chamber 19 and reciprocates in the direction of arrow G by a guide (not shown). A link 62 is connected to the shutter 71 and is connected to the shutter driving bar 63. The shutter drive bar 63 rotates in the same rotation direction I as the rotation direction H of the toner amount detection bar 15 as in the first embodiment.

  In this case, the shutter 71 is made of a flexible film such as polyester and has an outer diameter larger than the inner diameter of the toner supply port 14. By doing so, as shown by an arrow N, it can fall freely toward the toner holding chamber 19 side, but cannot fall down toward the toner cartridge 22 side. That is, the shutter 71 allows the toner to pass only from the toner cartridge 22 side to the toner holding chamber 19 side at a position where the toner supply port 14 is shielded.

  FIG. 7 is an explanatory diagram showing the operation of the shutter according to the second embodiment. In the second embodiment, since the shutter 22 is formed so as not to fall toward the toner cartridge 22 side, the toner amount detection bar 15 is moved from the lowest point to the highest point as shown in FIG. The toner flow can be dispersed in the directions of arrows L and M to prevent the backflow of toner to the toner cartridge 22.

  FIG. 8 is an explanatory diagram showing the action of the shutter according to the second embodiment. In the second embodiment, the shutter 71 can freely fall to the toner holding chamber 19 side. Therefore, as shown in FIG. 8, when the toner upper surface 67 in the toner holding chamber 19 is at a low position, for example, when the toner cartridge 22 is set in a new developing device, or when the toner cartridge 22 is replaced due to a decrease in the remaining amount of toner. When the toner supply from the toner cartridge 22 is desired to be performed immediately, the shutter 71 is normally moved to the toner holding chamber 19 side by the weight of the toner in the toner cartridge 22 even if the shutter 71 is in a position where the toner supply port 14 is shielded. The toner can be supplied in the direction of arrow P, and the preparation for printing is completed in a short time.

  As described above, according to the second embodiment, the shutter 71 can be freely tilted toward the toner holding chamber 19, so that the toner can be used even when the shutter 71 is in a position where the toner supply port 14 is shielded. When the amount of toner is small, the shutter 71 falls to the toner holding chamber 19 side, and the toner can pass only from the toner cartridge 22 side to the toner holding chamber 19 side, which has an effect of shortening the print preparation time.

  Each of the embodiments described above has been described with reference to an example of use in a printer. In addition, this invention is not limited to the said embodiment, It can change variously based on the meaning of this invention, and does not exclude them from the scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Electrophotographic printer 14 Toner supply port 15 Toner amount detection bar 19 Developer holding chamber 22 Toner cartridge 55 Developing device 61 Shutter 62 Link 63 Shutter drive bar

Claims (6)

A developer container for containing the developer;
A developer holding chamber for holding the developer supplied via the developer supply port provided in the center of the developer container;
A stirring member that performs a stirring operation of the developer below the developer supply port in the developer holding chamber;
A shielding member provided to shield the developer supply port and to be opened and closed;
The developing device according to claim 1, wherein the shielding member opens and closes in conjunction with the stirring operation of the stirring member.   2. The interlocking is characterized in that, during the stirring operation of the stirring member, the stirring member operates to shield the developer supply port during the stirring operation toward the developer supply port. Development device. The stirring member is a stirring bar that is rotationally driven,
The developing device according to claim 2, wherein the shielding member is operated by rotation of a drive bar connected via a link, and the drive bar is driven by rotation of the stirring bar.   4. The device according to claim 1, wherein the shielding member allows the developer to pass only from the developer container side to the developer holding chamber side at a position where the developer supply port is shielded. 2. The developing device according to claim 1.   The developing device according to claim 4, wherein the shielding member is a flexible member. An image forming apparatus comprising the developing device according to claim 1.

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