JPH08675Y2 - Color image forming device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a color image forming apparatus having a plurality of developing devices incorporated therein, and more particularly to improvement of a drive system thereof.

[Background of the invention]

In an electrophotographic image forming apparatus that forms a multi-color image such as a full-color image or a functional color image, a charger that charges a photoconductor drum that is an image forming body, an image exposure unit that exposes an image on the photoconductor drum, and a photoconductor A developing device that develops the electrostatic image on the drum with toner, a transfer device that transfers the toner image on the photosensitive drum to recording paper, and the like are arranged around the photosensitive drum.

Of these, the developing devices in the electrophotographic image forming apparatus for a full-color image are three or four units that respectively store yellow (Y), magenta (M), cyan (C) toner, and sometimes black (BK) toner. It is composed of a developing device, and while the photosensitive drum rotates 3 or 4 times,
A yellow (Y), magenta (M), and cyan (C) black (BK) toner image is formed on the photosensitive drum, and a full-color image is obtained by transferring the toner image onto a recording paper. There is. When such an image forming method is used, the color image forming apparatus can be made compact by thinning the three or four developing devices and by disposing them closely.

Japanese Unexamined Patent Publication No. 61-55661 proposes a color image forming apparatus using such an image forming method, in which latent images are formed by three exposure devices corresponding to three developing devices, respectively. The developing device and the cleaning means are integrated into a unit so that the process cartridge can be taken out from the apparatus main body.

Further, Japanese Patent Application No. Sho 62-320596 discloses that one developing device is used and the developing devices are arranged so as to be overlapped with each other so that the developing device can be taken out from the main body of the device.

In this way, the unitized process cartridge is structured such that the above-mentioned photosensitive drum and each developing device accommodated when mounted in the apparatus main body are connected to the power system and electric power system on the apparatus main body side so that they can be driven respectively. Is taken.

A single motor is usually used as the driving force source of the power system, and the motor directly drives the photosensitive drum in one series and a plurality of motors in the other series via a gear series of two systems. A method in which the developing device group is selectively driven and rotated via a clutch or the like is adopted, and in particular, the gear train for driving the developing device group is structurally disposed on the process cartridge side.

[Problems to be solved by the invention]

However, in a color image forming apparatus that forms a color toner image by superposing toner images of such a specific color, the photosensitive drum is continuously rotated during image formation, while the toner of each color is used. The developing device accommodating the toner tends to be intermittently operated, and as a result, a large load fluctuation is applied to the driving force source to make the rotation of the photosensitive drum unstable.

In particular, in a color image forming apparatus that forms an image using a digital image signal, since latent images are written on the photoconductor by forming high-resolution dots, fluctuations and load fluctuations due to the operation of each power source in the apparatus are The gap may be changed to cause image blur or dot connection, which may cause a fatal image defect.

Above all, in the above-mentioned device for forming a color image by superimposing, the dot formation is repeated a plurality of times to superimpose them, and in particular, vibration and unevenness in rotation are disliked, so it is strongly necessary to install a stable driving force and a driving mechanism for transmitting it. Required.

For this reason, in the color image forming apparatus, at least the photosensitive drum and the developing devices have different operation purposes, and therefore, it is preferable that the color image forming apparatus be driven by a power source having a performance suitable for each operation purpose. .

As a result of solving this problem and improving the present invention, the photosensitive drum and each developing device are rotated by a stable driving force without mutual influence of loads, and further, the process cartridge is reduced in weight to facilitate handling and maintenance. For convenience. The purpose is to provide a color image forming apparatus.

[Means for solving problems]

The above-mentioned object is a color having at least an image forming body and a plurality of developing devices arranged symmetrically with respect to a plane passing through an axis of the image forming body and arranged in parallel at a peripheral portion of the image forming body. A color image forming apparatus in which a process cartridge is detachably provided in an apparatus main body, wherein the apparatus main body includes a drive source for the image forming body and a single drive source for driving the plurality of developing devices separately. And a drive shaft of a drive source of the image forming body and a drive shaft of a drive source of the plurality of developing devices are provided on the plane, and the color process cartridge includes the single drive of the plurality of developing devices. A driving mechanism for driving each developing device from a power source through a clutch, and when the color process cartridge is mounted on the apparatus main body, the plurality of developing devices of the color process cartridge are arranged. Color image forming apparatus characterized by being configured for insertion from.

〔Example〕

 One embodiment of the present invention is shown in FIGS.

 FIG. 1 shows an embodiment in which the present invention is applied to a printer.

The printer has a clamshell type structure in which an upper housing 1 including a transfer belt and an apparatus main body 2 corresponding to a lower housing including a color process cartridge are divided, and the upper housing 1 is the apparatus main body 2 It can be held by being opened at a predetermined angle by a screw number that is coupled to, and is integrated with the main body 2 of the apparatus by a stopper fitting in a closed state.

The photoconductor drum 30, which is an image forming body forming the image forming portion of the printer, the developing devices 36, 37, 38, 39 containing the yellow, magenta, cyan and black developers, and the pressure release mechanism for the image forming body. Cleaning device 40 with it and charger
Each of the 35 pieces of equipment is united by being housed in the integrated color process cartridge 3.

The unitized process cartridge 3 is vertically inserted into the main body 2 of the apparatus by opening the upper housing 1 as shown in FIG. 2 and placed on the pedestal 4 at the bottom. After that, it is fixed to the storage position by the action of a pressing member (not shown) that interlocks with the lid of the upper housing 1.

In the process cartridge 3, the developing devices 36, 37, 38, 39 are distributed to the left and right with respect to the center line of the photosensitive drum 30, that is, the developing device 36 is separated from the axis of the photosensitive drum 30. 37 is on the right side, and developing units 38 and 39 are arranged symmetrically on the left side, respectively, and the developing sleeves of the developing units 36 and 37 arranged further on the right side are clockwise.
Further, each developing sleeve of the developing devices 38 and 39 arranged on the left side is rotated counterclockwise so that the developing action of each image is performed.

By arranging such a group of developing devices and further rotating the developing sleeve in the opposite direction, the process cartridge 3 has a good balance of left and right in terms of weight and power transmission mechanism, and is easy to handle. Moreover, the generation of harmful vibrations is prevented in advance.

In addition, the developing devices placed at the left and right symmetrical positions can have the same structure, and the scraping of the toner from the developing sleeve after the developing operation is completed is very efficiently performed by the action of gravity. It has the advantage that it can always be supplied with a fresh and proper amount of toner.

On the other hand, the cleaning device for the photosensitive drum 30
Toner collection boxes 47 are installed at symmetrical positions of 40 to improve the weight balance between the left and right of the process cartridge 3. A toner carrying screw 48 is provided between the toner collecting box 47 and the cleaning device 40.
A toner carrying pipe 49 containing a toner is built up on the front surface of the process cartridge 3, and the waste toner separated from the peripheral surface of the photosensitive drum 30 by the blade 40A is carried by the thrust of the toner carrying screw 48 to collect the toner. Collected inside Box 47.

Further, since all the developing devices are kept in the posture with the opening thereof facing upward, the developer does not flow out and drop, or the developer is not mixed into other developing devices.

In the printer, the laser writing system unit B is arranged in the space on the side of the process cartridge 3, and the recording paper conveyance surface is arranged in a portion extending over both the upper casing 1 and the apparatus main body 2 above the process cartridge 3. The photosensitive drum 30 receives a laser scan from the laser writing system unit B from diagonally below and transfers a color toner image formed by being superposed on the peripheral surface thereof to the lower surface of the recording paper. ing.

The process of copying a color image by the printer is performed as follows.

First, the formation of a multicolor image according to this embodiment is performed according to the image forming system shown in FIG. That is, the data obtained by the color image data input section (FIG. 3 (a)) in which the image sensor scans the original image is processed by the image data processing section (FIG. 3 (b)) equipped with a computer. Image data is created and is temporarily stored in the image memory (FIG. 3C). Next, the image memory is taken out at the time of recording and is input to the recording unit (FIG. 3D), for example, the color image forming apparatus shown in the embodiment of FIG.

That is, when a color signal output from an image reading device separate from the printer is input to the laser writing system unit B, a laser beam generated by a semiconductor laser (not shown) in the laser writing system unit B. Is rotated and scanned by the polygon mirror 32 rotated by the drive motor 31, the optical path is bent by the mirror 34 through the fθ lens 33, and the peripheral surface of the photosensitive drum 30 previously charged by the charger 35 as charging means. It is projected on to form a bright line.

On the other hand, when scanning is started, the beam is detected by the index sensor, the modulation of the beam by the first color signal is started, and the modulated beam is transferred to the photosensitive drum 30.
On the peripheral surface of. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the photosensitive drum 30 by the main scanning by the laser beam and the sub-scanning by the rotation of the photosensitive drum 30. This latent image is developed by the developing device 36 loaded with yellow (Y) toner (visual medium) in the developing means,
A toner image is formed on the drum surface. The obtained toner image passes under the cleaning device 40, which is a cleaning means separated from the peripheral surface of the photosensitive drum 30, while being held on the drum surface, and enters the next copy cycle.

That is, the photoconductor drum 30 is recharged by the charger 35, and then the second color signal output from the signal processing unit is input to the writing system unit B, which is the case of the first color signal described above. Similarly, writing is performed on the drum surface to form a latent image. The latent image is developed by the developing device 37 loaded with magenta (M) toner as the second color.

The magenta (M) toner image is formed in the presence of the previously formed yellow (Y) toner image.

A developing device 38 having cyan (C) toner forms a cyan (C) toner image on the drum surface based on a control signal generated by a signal processing unit.

Further, 39 is a developing device having a black toner, which forms a black toner image on the surface of the drum in a superposed manner by the same process. A DC or even AC bias is applied to the sleeves of the developing units 36, 37, 38, and 39, and jumping development is performed by a two-component developer that is a developing means, and a photoconductor on which a substrate is installed. The drum 30 is designed to be developed in a non-contact manner.

Thus, the color image formed on the peripheral surface of the photosensitive drum 30 is recharged by the charger 9 and then transferred to the lower surface of the recording paper sent from the paper feed cassette C through the paper feed roller and the paper feed guide in the transfer section. Transcribed.

That is, this multicolor toner image is charged by the pre-transfer charger 9 to facilitate transfer, and then the transfer belt 50, which has been rotated from the start of transfer, is brought into contact with the photoconductor drum 30 and fed from the paper feed cassette C. Roller 12 and timing roller
It is transferred via 13 to the supplied recording paper at the same timing as the image formation.

The structure of the transfer belt 50 is such that a comb belt containing a conductive cloth as a base body is provided with an elastic layer of 0.5 mm thickness on the outer periphery thereof, and further an insulating layer (dielectric layer) of 50 μm is provided on the outer periphery thereof. The transfer belt 50 is brought into contact with or separated from the photosensitive drum 30 by stretching the rollers 60a, 60b and 60c and rotating them by driving the roller 60a, and moving the roller 60b up and down. The transfer belt 50 is charged by the transfer device 51,
To the surface, a transfer charge having a polarity opposite to that of the toner of about 1.5 KV to 3.0 KV is applied and transfer is performed. Reference numeral 66 is a cleaning device for the transfer belt which cleans the transfer belt 50.

On the other hand, a photosensitive drum with recording paper separated from the drum surface
The blade 40A of the cleaning device 40 comes into contact with the cleaning device 30 to remove the residual toner, and after the completion of the cleaning process, the cleaning device 40 is separated from the peripheral surface of the drum again to start a new color image format process.

In this way, the recording paper is the above-mentioned process cartridge 3
Since the toner is spilled or scatters from the cleaning device 40 or the like because it is conveyed in the horizontal direction above and the transfer surface faces downward, the image surface is not polluted. The transferred recording paper is ejected to the outside through the fixing roller 80 and the paper ejection roller 90.

The photosensitive drum 30 and each developing unit are rotatably operated by the drive mechanism shown in FIG. 4 and FIG. 5 showing the AA cross section.

In the figure, 3A is a bearing portion of the photosensitive drum 30 formed in the process cartridge 3, and G30 is a rotating shaft 3 of the photosensitive drum 30.
The gear G30 is fixed to 0A, and the gear G30 is housed in the bearing portion 3A, and a part of the gear is seen through a notch below the bearing portion 3A.

G1 and G2 are each a pair of gears on the same axis center using exactly the same four gears.
Rotation is transmitted via C1 and C2 only to the gears on the driven side opposite to each other on the same axis only when rotating in a fixed direction.

G36, G37, G38, and G39 are electromagnetic clutches C with respect to the rotary shafts of the developing sleeves 361, 371, 381, and 391 built in each developing device.
In the gears connected via 36, C37, C38, and C39, the rotation of each developing sleeve is interrupted by turning on or off each electromagnetic clutch.

The gears G37 and G38 mesh with the driven gears of the gears G1 and G2, respectively, and further to the intermediate gears G3 and G39 with respect to the gears G36 and G39.
Connect via G4 and thus developing sleeves 361 and 371 and 38
Both 1 and 391 rotate in the same direction.

On the other hand, GA and GB are drive gears protruding from the substrate 2d on the rear side of the apparatus main body 2, and are connected to separate drive force sources, that is, drive motors incorporated in the apparatus main body 2.

Therefore, when the process cartridge 3 is vertically inserted into the apparatus main body 2 from above and mounted, the gear G20 meshes with the gear GA, and simultaneously the gears G1 and G2 mesh with the gear GB as shown in FIG. Various drive mechanisms are configured.

Thus, the drive mechanism of the developing device unit can be configured symmetrically with respect to the rotation shaft 30A of the photoconductor drum 30 by the above-mentioned gear series, and even if the process cartridge 3 is attached or detached, the gear mechanism is simplified. The engagement and the separation can be performed easily and surely.

Further, by separating the photoconductor drum 30 and the drive motor for each developing device unit from each other, as a drive motor suitable for each function, for example, a pulse motor having a stable rotation speed for the photoconductor drum 30 and one for the developing device unit are used. As a result, it is possible to avoid the influence of load fluctuations by using a powerful and robust reversible motor.

 The drive mechanism described above is operated as follows.

In synchronization with the rotation of the photoconductor drum 30 on which the latent image corresponding to the first color is formed, the drive motor on the side of the developing unit starts stopping rotation, and the gear GB rotates clockwise to open the one-way clutch C1. The gears G36 and G37 are simultaneously rotated in the clockwise direction. At this stage, only the electromagnetic clutch C36 is turned on, and the developing sleeve 361 of the developing device 36 develops with yellow toner. Since the electromagnetic clutch C37 is OFF and the one-way clutch C2 is inoperative, the developing sleeves 371, 381, 391 do not rotate and the developing operation by the developing devices 37, 38, 39 is not performed.

At the stage when the latent image corresponding to the second color is formed on the yellow toner image, only the electromagnetic clutch C37 is turned on, and the developing sleeve 371 of the developing device 37 develops the latent image with magenta toner. .

Further, for each of the third and fourth colors, the drive motor is switched to the reverse rotation, the one-way clutch C2 is used, and only the electromagnetic clutch C38 or C39 is turned on to perform the developing operation of the developing device 38 or 39 as described above. A color toner image is formed by superimposing toner images of respective colors.

On the other hand, regarding the mutual positional relationship between the gear train of the driving mechanism provided on the color process cartridge 3 side and the driving force source arranged on the apparatus main body 2 side, the gears G30 and G2 protruding from the rear side of the process cartridge 3 are used. The gear G2 by changing the position in the front-back direction as shown in FIG.
It is possible to arrange the drive mechanism directly below the G30, and as a result, the layout of the drive mechanism can be symmetrical with respect to the center axis of the photosensitive drum 30.

Therefore, as shown in FIG. 6, if the structure is such that the bearing portions 3A at the front and rear of the process cartridge 3 are inserted into the apparatus main body 2 using the guide grooves 101C and 101D provided on the substrates 2C and 2D as guides, the gear 30A becomes the gear GA. Further, the gears G1 and G2 can be easily and surely engaged with the gear GB to be connected to the driving force source.

[Advantages of the Invention] According to the present invention, it becomes possible to operate the image forming body and the developing unit with a driving force source having characteristics suitable for their respective functions, and the image forming body and the developing unit, etc. Can be easily and surely connected or disconnected to and from the driving force source by simply attaching and detaching the process cartridge containing the By overlapping with the drum axis drive center, there is less shake of the drum, and in particular, there is provided a color image forming apparatus with good color image quality and excellent handleability that reduces misalignment and blurring when forming overlapping dots. became.

[Brief description of drawings]

1 and 2 are sectional views of a color image forming apparatus of the present invention, FIG. 3 is a block diagram showing an image forming system, and FIG.
FIG. 5 and FIG. 5 are a front view and a sectional view of a main part of a drive system of a process cartridge housed in the apparatus, and FIG. 6 is a perspective view showing a mounted state of the process cartridge in the apparatus. 1 ... Upper housing, 2 ... Device body 2C, 2D ... Substrate 3 ... Color process cartridge 3A ... Bearing section, 4 ... Receiving stand 30 ... Photosensitive drum 36,37,38,39 ...... Developing device, 101C, 101D …… Guide groove GA, GB …… (for driving) gear 351,371,381,391 …… Developing sleeve C1, C2 …… One-way clutch C36, C37, C38, C39 …… Electromagnetic clutch

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Established by Noriko Naganuma 2970 Ishikawa-cho, Hachioji-shi, Tokyo Konica Co., Ltd. (72) Creator Masahiko Itaya 2970 Ishikawa-cho, Hachioji, Tokyo Konica Co., Ltd. Yoshiaki Kawasaki (56) Reference JP-A 62-43662 (JP, A) JP-A 62-115179 (JP, A) JP-A 64-971 (JP, A)

Claims (2)

[Scope of utility model registration request] 1. At least an image forming body, and a plurality of developing devices arranged symmetrically with respect to a plane passing through an axis of the image forming body and arranged in parallel at a peripheral portion of the image forming body. A color image forming apparatus in which a color process cartridge is detachably provided to an apparatus main body, wherein the apparatus main body includes a drive source for the image forming body and a single drive source for driving the plurality of developing devices. Separately, the drive shaft of the drive source of the image forming body and the drive shaft of the drive source of the plurality of developing devices are provided on the plane, and the color process cartridge includes the single developing device of the plurality of developing devices. A drive mechanism for driving each developing device from a drive source via a clutch is provided. When the color process cartridge is mounted on the apparatus main body, the plurality of developing devices of the color process cartridge are arranged. Color image forming apparatus characterized by being configured for insertion from the side. 2. The color image forming apparatus according to claim 1, wherein the color image forming apparatus has a two-divided structure which is opened vertically, and the color process cartridge is attachable to and detachable from a lower housing. .