JP4000443B2 - Rotary developing unit and color image forming apparatus - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an image forming apparatus such as a copying machine, a printer, and a fax machine using electrophotography, and a plurality of developing units having a developer conveying means are arranged along a cylindrical outer periphery, and the developing units are selectively provided. The present invention relates to a rotary developing unit that rotates to a developing position and develops a latent image on an image carrier and an image forming apparatus.
[0002]
[Prior art]
As an image forming apparatus using electrophotography, an electrostatic latent image of a plurality of colors is sequentially formed on a photoreceptor, and the electrostatic latent image is sequentially developed into each color toner image by a rotary developing device. There is a system in which the image is transferred onto a transfer medium, transferred, a full color toner image transferred onto the intermediate transfer medium is transferred to a transfer material, and then fixed.
[0003]
The rotary developing device is provided with a rotating body facing the photoreceptor, and a plurality of developing units (yellow, cyan, magenta, black developing units) are mounted in the rotating body, and the rotating body is rotated and moved. The electrostatic latent image is developed with toner by selectively bringing one of the plurality of developing units into contact with the developing position of the photosensitive member, rotating the developing roller in the developing unit and applying a developing bias. Yes.
[0004]
Conventionally, in a color image device equipped with a rotary developing device, as proposed in, for example, Japanese Patent Publication No. 4-10070, the shaft is fixed to a predetermined position along the movement path to the developing position by an elastic member. As a member that supports the drive gear in a movable manner and restricts the swinging amount of the drive gear, there is a restricting member that keeps the input gear of the developing roller and the drive gear engaged. Also, as a positioning of the photoconductor and the photoconductor to ensure an appropriate gap between the photoconductor and the photoconductor, the developing device is urged in the direction of the photoconductor, and a roller arranged coaxially with the development roller is pushed against the photoconductor. A hitting method is known.
[0005]
[Problems to be solved by the invention]
However, in the above conventional proposal, since the meshing between the drive input gear of the developing device guided to the developing position by the rotation of the rotary and the drive output gear on the main body side is ensured, the cartridge is mounted on the rotary developing unit as a cartridge. The variation in the developing device affects the meshing between the drive input gear and the drive output gear, and there is a problem that the meshing state between the drive input gear and the drive output gear varies depending on the developing device of each cartridge and each color. Further, the conventional proposal does not disclose or suggest a simple configuration that positively biases the developing device toward the photosensitive member.
[0006]
[Means for Solving the Problems]
The present invention solves the above-described problem, and can stably bias the developing roller in the direction of the photosensitive member during transmission of developing driving, and facilitates securing a gap between the photosensitive member and the developing roller. .
[0007]
To this end, the present invention provides a rotary developing unit or a unit for developing a latent image on a photosensitive member by detachably mounting a plurality of developing units along the outer periphery of a cylinder and selectively rotating the developing unit to a developing position. As the color image forming apparatus provided, a plurality of idler gears are provided on the rotary frame corresponding to the attachment / detachment positions of the plurality of developing devices, a positioning pin is provided at the tip of the rotating shaft of the idler gear, A positioning hole for fitting to the positioning pin at the time of mounting and a swing fulcrum on the opposite side of the positioning hole on the rotation axis of the idler gear are provided, and the input gear of the train wheel composed of the input gear and the developing roller gear is meshing the idler gear, the axis of rotation of the meshing point between the input gear and the idler gear the idler gear and the developing roller gear Corresponding to the developing device that is supported by the positioning pin and the swing fulcrum so that it can be swung on the inner side in the radial direction of the rotary developing unit and on the upstream side of the rotation direction of the idler gear, and rotated to the developing position. The idler gear is configured to mesh with the drive output gear on the outer periphery of the cylinder.
[0008]
Further, the rotary frame is provided with a biasing spring for biasing the developing device that swings around the positioning pin and the swinging fulcrum in the direction of the photosensitive member .
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a color image forming apparatus according to the present invention. 1 is a drive output gear, 2 is a rotary idler gear, 3 is a developing cartridge input gear, 4 is a developing roller gear, and 10 is rotary developing. A unit, 22 is a developing roller, and 23 is a photoreceptor.
[0010]
In FIG. 1, a rotary developing unit 10 shows an example of a unit configuration for four-color development. A drive output gear 1 is disposed on the apparatus frame side (not shown) and is connected to a drive motor. Is rotatably arranged in the rotary developing unit 10 so as to mesh with the drive output gear 1. The positioning of the developing device 21 is set as a rotation center axis of the rotary idler gear 2 and can be swung with respect to the photosensitive member 23 around the rotation center axis. The developing device 21 is generated by meshing of the rotary idler gear 2 and the developing cartridge input gear 3 in the configuration of the gear train, in which the train consisting of the developing cartridge input gear 3 and the developing roller gear 4 meshes with the rotary idler gear 2. The driving force is set so that the developing unit 21 rotates in the radial direction of the rotary developing unit 10, that is, toward the center of the photosensitive member 23.
[0011]
The rotational direction in which the driving force generated by the engagement between the rotary idler gear 2 and the developing cartridge input gear 3 is directed toward the center of the photosensitive member 23 is, for example, as shown in FIG. In this direction, the rotary idler gear 2 is located upstream of the meshing point. In addition, the train wheel is disposed radially inward of the rotary developing unit 10 with respect to the line connecting the developing cartridge input gear 3 to the rotary shaft of the rotary idler gear 2 and the developing roller gear 4. In other words, the meshing point between the rotary idler gear 2 and the developing cartridge input gear 3 is on the radially inner side of the rotary developing unit 10 with respect to the line connecting the rotary shafts of the rotary idler gear 2 and the developing roller gear 4. 2 upstream in the rotational direction.
[0012]
Next, a specific positioning and swing mechanism of the developing cartridge will be described. 2 is a diagram showing a state where the developing cartridge is mounted on the rotary developing unit, FIG. 3 is a diagram showing an enlarged detail of the developing cartridge cover portion, and FIG. 4 is a member that realizes positioning and swinging of the developing device in the rotary developing unit. FIG. 5 is a view showing a structure, and FIG. 5 is a view showing a meshing state of a rotary idler gear and a drive output gear. In the drawing, 6 is a rotary frame, 7 is a drive motor, 11 is a developing cartridge cover, 12 is a developing cartridge swinging fulcrum, 13 and 16 are developing cartridge positioning pins, 14 and 15 are developing cartridge positioning holes, and 17 is a developing cartridge attached. A biasing spring, 21 is a developing device, and 22 is a developing roller.
[0013]
FIG. 2 shows a state in which the developing device 21 for only one of the four colors is attached to the rotary developing unit 2, and FIG. 3 is an enlarged detailed view of the periphery of the developing cartridge cover 11. The developing cartridge cover 11 has projections at two positions on the opposite side of the developing cartridge positioning pin 13 and the developing roller 22, and engages with the developing cartridge positioning hole 14 provided on the end face of the rotary frame 6 facing these. It is like that. The developing cartridge swinging fulcrum 12 is at a portion facing the rotary shaft of the rotary idler gear 2. A rotary idler gear 2 is provided on the rotary frame 6 on the opposite side of the developing cartridge swinging fulcrum 12 so as to show the inside of the rotary developing unit from which the developing device 21 is removed. A developing cartridge positioning pin 16 is provided on the rotating shaft, and a developing cartridge positioning hole (not shown) of the developing device 21 is fitted to the rotating cartridge to swing the developing device 21 between the developing cartridge swinging fulcrum 12. I try to move it. Further, the rotary frame 6 in the rotary developing unit is provided with a developing cartridge urging spring 17 for urging the developing device 21 toward the photosensitive member as shown in FIG.
[0014]
As described above, the developer cartridge positioning holes 14 and 15 shown in FIG. 4 are fitted with the developer cartridge positioning pin 13 of the developer cartridge cover 11 and another developer cartridge positioning pin (not shown) shown in FIG. The developing device 21 is positioned by fitting with a developing cartridge positioning hole (not shown) of the developing device 21. On the other hand, the developing cartridge swings by the developing cartridge swinging fulcrum 12 and the developing cartridge positioning pin 16. Then, the rotary idler gear 2 meshes with the drive output gear 1 as shown in FIG. 5 and is driven by the drive motor 7.
[0015]
Therefore, the developing device 21 can be positioned with high accuracy in a swingable manner on the rotary developing unit 10 by the positioning mechanism. Moreover, the engagement and disengagement of the train wheel during the attachment and detachment is performed between the rotary idler gear 2 disposed on the rotary frame 6 and the developing cartridge input gear 3, and at the tip of the rotary shaft of the rotary idler gear 2. Since the developer cartridge positioning pins 16 are used for positioning, play and play can be reduced and the engagement and disengagement can be performed smoothly. When the rotary developing unit 10 is rotated so that the developing device 21 corresponding to the color of the developing process is at the developing position, the drive output gear 1 is a rotary idler gear disposed on the rotary frame 6 of the rotary developing unit 10. 2 is engaged.
[0016]
FIG. 6 is a diagram showing an embodiment of an image forming apparatus provided with a rotary developing unit according to the present invention, in which 21 is a developing device, 22 is a developing roller, 23 is a photoreceptor, 24 is a primary transfer device, and 25 is Intermediate transfer medium, 26 is a secondary transfer device, 27 is a laser writing unit, 28 is a paper feed tray, 29 is a paper feed roller, 30 is a registration roller, 31 is a conveyance path, 32 is a fixing device, 33 is a discharge device, 34 Indicates a paper discharge tray.
[0017]
As shown in FIG. 6, the image forming apparatus having the rotary developing unit according to the present invention uniformly distributes the photoconductor 23 along the rotation direction on the outer periphery of the photoconductor 23 that is a latent image carrier of the process unit 11. Formed on the photosensitive member 23, a laser writing unit 27 for forming an electrostatic latent image on the photosensitive member 23, a rotary developing unit 10 for developing the electrostatic latent image, and the photosensitive member 23. An intermediate transfer medium 25 for transferring a monochrome toner image, a primary transfer device 24, and the like are provided. The photoreceptor 23 includes a thin cylindrical conductive substrate and a photosensitive layer formed on the surface thereof. Then, the recording medium (paper or the like) is conveyed from the paper feed tray 28 through the paper feed roller 29 and the registration roller 30 to the secondary transfer device 26, and the recording medium on which the four full-color images are transferred by the secondary transfer device 26 is discharged. A fixing device 32 and a discharge device 33 for fixing the toner image are disposed on a path for conveying the paper tray 34.
[0018]
In the rotary developing unit 10, four developing devices 21 of yellow Y, cyan C, magenta M, and black K are rotatably arranged, and the developing of one developing device 21 is selectively performed every rotation of the photosensitive member 23. A developing roller 22 that is an agent carrying member can come into contact with the photosensitive member 23. Each developing device 21 is connected to a toner cartridge containing the respective toner so as to replenish the toner. When an image forming signal is input from a computer (not shown), the photosensitive member 23, the developing roller 22 of the rotary developing unit 10, and the intermediate transfer medium 25 are rotated. First, the outer peripheral surface of the photosensitive member 23 is charged by a charging device. Uniformly charged. Thereafter, the laser writing unit 27 performs selective exposure according to image information of the first color, for example, Y, and a yellow electrostatic latent image is formed on the surface of the photoconductor 23. At this time, the rotary developing unit 10 is rotated and brought into contact so that the developing roller 22 of the yellow developing unit contacts the photoconductor 23. As a result, a yellow electrostatic latent image toner image is formed on the photoreceptor 23. Thereafter, a primary transfer voltage having a polarity opposite to the charging polarity of the toner is applied to the primary transfer device 24, and the toner image formed on the photoreceptor 23 is transferred onto the intermediate transfer medium 25. During this time, the secondary transfer device 26 is separated from the intermediate transfer medium 25.
[0019]
The above processing is repeatedly executed corresponding to the second color, the third color, and the fourth color of the image forming signal, so that toner images of four colors corresponding to the contents of each image forming signal are transferred to the intermediate transfer medium 25. The image is superimposed and transferred on the top to form a full color image. At the timing when the full color image reaches the secondary transfer device 26, the recording medium is conveyed from the conveyance path 31 through the registration roller 30 to the secondary transfer device 26, and the secondary transfer device 26 is pressed against the intermediate transfer medium 25. A secondary transfer voltage is applied, and the full-color toner image on the intermediate transfer medium 25 is transferred onto the recording medium. The full color toner image transferred onto the recording medium in this way is fixed by being heated and pressed by the fixing device 32. The image forming apparatus is a color electrophotographic printer capable of forming a full color image with four colors of toner, but the present invention is not limited to this, and all color images using electrophotography are used. It can be applied to a forming apparatus.
[0020]
In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the above embodiment, the rotation direction is determined so that the driving force generated by the meshing of the rotary idler gear and the drive output gear moves the developing device toward the center of the photosensitive member. The rotation direction may be determined.
[0021]
【The invention's effect】
As is clear from the above description, according to the present invention, a plurality of developing devices are detachably mounted along the outer periphery of the cylinder, and the developing devices are selectively rotated to the developing position so that a latent image on the photosensitive member is formed. In the rotary developing unit to be developed, an idler gear is provided at a position corresponding to each developing device of the rotary developing unit, the gear wheel of the developing device is meshed with the idler gear, and the idler gear is meshed with the drive output gear at the developing position. Since it is configured to match, the developing roller can be stably urged in the direction of the photosensitive member by the driving force generated by the meshing of the rotary idler gear and the developing cartridge input gear when the developing drive is transmitted. It is easy to secure the gap. Further, an urging force by an excessive elastic member becomes unnecessary, and image deterioration and toner scattering due to an impact between the developing unit and the photosensitive member can be prevented. Furthermore, by providing an idler gear at a position corresponding to each developing device of the rotary developing unit, when the developing unit is replaced, the load of the transfer gear due to the variation of the developing unit can be reduced by the idler gear arranged in the rotary developing unit. .
[Brief description of the drawings]
FIG. 1 is a diagram for explaining an embodiment of a rotary developing unit according to the present invention.
FIG. 2 is a diagram illustrating a state in which a developing cartridge is mounted on a rotary developing unit.
FIG. 3 is a diagram showing enlarged details of a developing cartridge cover portion.
FIG. 4 is a diagram showing members and structures for realizing positioning and swinging of a developing device in a rotary developing unit.
FIG. 5 is a diagram illustrating a meshing state of a rotary idler gear and a drive output gear.
FIG. 6 is a diagram illustrating an embodiment of an image forming apparatus including a rotary developing unit according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 ... Drive output gear, 2 ... Rotary idler gear, 3 ... Developing cartridge input gear, 4 ... Developing roller gear, 10 ... Rotary developing unit, 22 ... Developing roller, 23 ... Photoconductor

Claims (3)

In a rotary developing unit in which a plurality of developing units are detachably mounted along the outer periphery of the cylinder, and the developing unit is selectively rotated to a developing position to develop a latent image on the photosensitive member, the mounting positions of the plurality of developing units are A plurality of idler gears are provided on the rotary frame correspondingly, and a positioning pin is provided at the tip of the rotating shaft of the idler gear,
The developing device is provided with a positioning hole that fits into the positioning pin at the time of mounting and a swing fulcrum on the opposite side to the positioning hole on the rotation axis of the idler gear, and a train wheel composed of an input gear and a developing roller gear The input gear meshes with the idler gear, and the meshing point between the idler gear and the input gear is radially inward of the rotary developing unit from the line connecting the idler gear and the rotation shaft of the developing roller gear, and the The idler gear is supported on the upstream side in the rotational direction of the idler gear so as to be swingable by the positioning pin and the swinging fulcrum, and the idler gear corresponding to the developing device rotated and moved to the developing position meshes with the drive output gear on the outer periphery of the cylinder. A rotary developing unit characterized in that it is configured as described above.   2. The rotary developing unit according to claim 1, wherein an urging spring is provided on the rotary frame for urging the developing device oscillating between the positioning pin and the oscillating fulcrum in the direction of the photosensitive member. In a color image forming apparatus provided with a rotary developing unit that detachably mounts a plurality of developing units along the outer periphery of a cylinder, selectively rotates the developing unit to a developing position, and develops a latent image on the photoreceptor.
A plurality of idler gears are provided on the rotary frame corresponding to the attachment / detachment positions of the plurality of developing devices, and a positioning pin is provided at the tip of the rotation shaft of the idler gears,
The developing device is provided with a positioning hole that fits into the positioning pin at the time of mounting and a swing fulcrum on the opposite side to the positioning hole on the rotation axis of the idler gear, and a train wheel composed of an input gear and a developing roller gear The input gear meshes with the idler gear, and the meshing point between the idler gear and the input gear is radially inward of the rotary developing unit from the line connecting the idler gear and the rotation shaft of the developing roller gear, and the The idler gear is supported on the upstream side in the rotational direction of the idler gear so as to be swingable by the positioning pin and the swinging fulcrum, and the idler gear corresponding to the developing device rotated and moved to the developing position meshes with the drive output gear on the outer periphery of the cylinder. A color image forming apparatus characterized in that it is configured as described above.

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