JPH06194889A - Color image forming device - Google Patents

Abstract

PURPOSE:To perform the supply of developer and the exchange of an image forming member by using the space of an exposure optical system. CONSTITUTION:On the upper part of a process cartridge 30 housing a photosensitive belt 1 stretched in a flat state being long sideways and developing devices 6, 7, 8 and 9 arranged in parallel on the upper surface of the belt 1; the group of a polygon mirror 5B and an ftheta lens 5C, and a mirror 5D constituting a laser write system unit 5 are separated and arranged on the right outside and the left outside of the developing device group in a state where they are respectively housed in containers A and B. The developer is supplied to the respective developing devices 6 to 9 and the developing devices 6 to 9 are exchanged by crossing an optical path between the ftheta lens 5C and the mirror 5D in a state where an upper cover II is opened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus which uses a laser optical system as an image exposing means and forms a color toner image on an image forming body by exposing and developing the image forming body a plurality of times. Regarding

[0002]

2. Description of the Related Art In the case of a color image forming apparatus using a plurality of developing devices for general paper, a flexible belt as an image forming member is used because of the purpose of suppressing the height of the device and the layout of the developing device. It is considered advantageous to use a strip photoreceptor. The belt-shaped photoconductor is stretched to have a flat shape in the horizontal direction, the developing devices are arranged in parallel on the lower peripheral surface, and the exposure optical system is arranged along the upper peripheral surface. The image forming unit is relatively compact, and the space for the exposure optical system is sufficient.

[0003]

However, when the developing device is arranged below the image forming body, there are problems in terms of toner replenishment and maintenance, and when the developing device is arranged above the image forming body, exposure is performed. There is a problem that the optical system has to be arranged on the lower side or the side portion of the image forming body, so that a sufficient space cannot be secured and the construction of the optical system becomes unreasonable.

The present invention solves this problem and improves it.
It is an object of the present invention to provide a color image forming apparatus that does not hinder the structure of the exposure optical system and allows the developing device to be arranged at a position that facilitates toner replenishment or maintenance work.

[0005]

SUMMARY OF THE INVENTION In a color image forming apparatus in which a plurality of developing devices are arranged in parallel around an image forming body, the above-described object is to provide a plurality of optical paths of an exposure optical system for performing image exposure on the image forming body. The color image forming apparatus, which is disposed on the upper surface of the developing device, supplies the developer to the developing device or attaches and detaches the image forming member across the optical path.

[0006]

FIG. 1 is a block diagram of a color image forming apparatus according to the present invention.
Through FIG.

FIGS. 1 and 2 show a first embodiment, in which 1 is a flexible photosensitive belt which is a belt-shaped image forming body, and the photosensitive belt 1 is composed of rotating rollers 2 and 3. It is installed horizontally between and is conveyed in the direction indicated by the arrow by the driving of the rotating roller 2.

Reference numeral 4 is a charging device, 5 is a laser writing system unit, 6 to 9 are respective developing devices for accommodating a developer of a specific color, 10 is a cleaning device, and 11 is a fixing device.

The developing units 6, 7, 8 and 9 are arranged in parallel on the peripheral surface of the photosensitive belt 1 and are, for example, yellow, magenta,
Developing sleeves 6 for accommodating cyan and black developers, respectively, which maintain a predetermined gap with the photosensitive belt 1.
A, 7A, 8A, and 9A are provided and have a function of visualizing the latent image on the photosensitive belt 1 by a non-contact reversal development method. Unlike the contact development, the non-contact development has an advantage that it does not hinder the movement of the photosensitive belt 1.

Further, the blade 10 of the cleaning device 10
A is kept at a position apart from the surface of the photosensitive belt 1 during image formation and is pressed against the surface of the photosensitive belt 1 as shown in the figure only during cleaning after image transfer.

The process for forming a color image by the above-mentioned color image forming apparatus is performed as follows.

First, the formation of a multicolor image according to this embodiment is performed according to the following image forming system. That is, the data obtained by the color image data input unit in which the image sensor scans the original image is processed by the image data processing unit to create image data, which is once stored in the image memory. Next, the image memory is taken out at the time of recording and is input to the color image forming apparatus shown in the embodiment of FIG.

That is, when a color signal output from the image reading apparatus separate from the image forming apparatus or a transmitted image signal is input to the laser writing system unit 5, the laser writing system unit 5 outputs a semiconductor laser. The laser beam generated by (not shown) is rotationally scanned by the polygon mirror 5B rotated by the drive motor 5A, and f
The optical path is bent by the mirror 5D through the θ lens 5C, and is projected onto the peripheral surface of the photosensitive belt 1 to which electric charges have been previously applied by the charger 4 to form a bright line.

On the other hand, when the 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 scans the peripheral surface of the photosensitive belt 1. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the photosensitive belt 1 by the main scanning by the laser beam and the sub-scanning by the conveyance of the photosensitive belt 1. This latent image is yellow (Y) in the developing means.
In the non-contact state, reversal development is performed by the developing device 6 in which the toner is loaded, and a toner image is formed on the belt surface. The obtained toner image passes under the cleaning device 10 which is separated from the peripheral surface of the photosensitive belt 1 while being held on the belt surface, and enters the next image forming cycle.

That is, the photoconductor belt 1 is recharged by the charger 4, and then the second color signal output from the signal processing unit is input to the writing system unit 5 to generate the first color signal described above. Writing is performed on the surface of the belt in the same manner as in the above case to form a latent image. This latent image is reversely developed in a non-contact state by the developing device 7 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.

Reference numeral 8 denotes a developing device having cyan (C) toner, which forms a cyan (C) toner image on the belt surface based on a control signal generated by a signal processing section.

Further, 9 is a developing device having a black toner, which is formed by superposing a black toner image on the belt surface by the same process. A DC or further AC bias is applied to each sleeve of each of these developing units 6, 7, 8 and 9 to perform jumping development with a one-component or two-component developer, and a photoreceptor belt 1 whose base is grounded. Development is performed in a non-contact manner.
Thus, the color toner image formed on the peripheral surface of the photosensitive belt 1 is transferred by the transfer roller 12 onto the transfer paper P which is carried out from the paper feed cassette 13 and fed through the timing roller 14.

The transfer paper on which the toner image has been transferred is separated from the peripheral surface of the photosensitive belt 1 and the toner image is fused on the fixing device 11 and then discharged onto the tray 15.

On the other hand, the photoreceptor belt 1 from which the transfer paper is separated
Is the blade 10A of the cleaning device 10 on the fifth lap
The residual toner is removed / cleaned by receiving the pressure contact of No. 1, and after one round, the charging is performed again by the charger 4 to start the next image forming process.

The photosensitive belt 1, the charging device 4, the developing devices 6 to 9 and the cleaning device 10 described above, including the waste toner box 16, are further housed in the process cartridge 30 and integrated with each other. The front door (not shown) provided on the is opened and slid in the depth direction to be attached / detached. The developing units 6 to 9 are mounted by being inserted into the upper surface of the process cartridge 30 from above, and the sleeves 6A to 9A are spaced from the peripheral surface of the photosensitive belt 1 by a pressure contact mechanism (not shown). Is located. Therefore, each developing device can be easily taken out by the process cartridge 30 independently by releasing the pressure contact mechanism.

On the other hand, the laser writing system unit 5 is
The polygon mirror 5B and the fθ lens 5 are divided into a group and a mirror 5D, which are housed in a container A and a container B, respectively. The group of the polygon mirror 5B and the fθ lens 5C is outside or right side of the developing device 9, and the mirror 5D is a developing unit. Bowl 6
The laser beam, which is fixed to the apparatus main body I so as to be positioned on the outer side, that is, on the left side, is rotationally scanned by the polygon mirror 5B, is reflected by the mirror 5D via the upper portion of each of the developing devices, and is projected onto the peripheral surface of the photosensitive belt 1. To be done.

Further, the apparatus main body I is provided with an upper lid II which can be opened and closed on the upper portion thereof, and by opening the upper lid II in a clockwise direction with a hinge H1 as a fulcrum, the above-mentioned developing devices open their upper portions widely. To be done.

When the upper lid II is closed as shown in FIG. 1, the holding member provided on the upper lid II has the shielding plates 51A provided in the openings 50A and 50B of the containers A and B, respectively.
And 51B by pressing respectively tension springs 52A and 52B
The opening portions 50A and 50B by lowering them against the bias of
However, when the lids are opened as shown in FIG. 2, the shielding plates 51A and 51B are attached with tension springs 52A and 52B by retracting the left and right pressing members 51C and 51C upward. It rises by force to close the openings 50A and 50B.

Therefore, when the developing devices are attached or detached, or when toner is replenished to the developing devices by the toner container T as shown in FIG.
The laser optical system is protected from toner adhesion and can always form a high-quality image with high resolution.

Further, as shown in the embodiment of FIG. 3, both the container A and the container B may be attached to the inner surface of the upper lid II to support the laser writing system unit 5 on the upper lid II side. In this case, since the container A and the container B are largely retracted above the respective developing devices at the same time when the upper lid II is opened, there is no fear of toner adhesion and therefore the above-mentioned shielding plate is not required, and the respective developing devices described above are not necessary. The process cartridge 30 may be attached and detached from the upper portion of the apparatus main body I together with the attachment and detachment of the toner container T and the replenishment of toner by the toner container T.

Each of the apparatus main bodies I described above is provided with a side door III that can be opened and closed on the side surface thereof, and the side door III stores a rotatable manual paper feed tray 40.

In the manual paper feeding, as shown in FIG. 1, the manual paper feeding stand 40 is rotated and set to a horizontal position, and the inserted transfer paper is fed through the manual paper feeding roller 17 to a timing roller.
Feed to 14.

In the case of jam handling, etc., the side door as shown in FIG.
By rotating III with the hinge H2 as a fulcrum in the counterclockwise direction, the transfer paper transport path is opened so that jam paper removal and maintenance work can be easily performed.

FIG. 5 shows the layout of the drive gears of the respective image forming members protruding to the back surface of the process cartridge 30, showing the state viewed from the right side surface of the apparatus main body I and the state viewed from the upper surface thereof. 5 (a) and 5
It shows in (b). In the figure, G1 is a gear on the extension shaft of the rotating roller 2 for driving the photosensitive belt 1, G6 to G9 are gears on the extension shafts of the sleeves 6A to 9A for driving the developing units, and G10 is a gear for driving the cleaning device 10. The above-mentioned gears have different positions in the horizontal direction as shown in FIG. 5B, and further, as shown in FIG. Since it is configured to be meshed with and connected to each drive gear of the drive unit from each other, the process cartridge 30 can be attached or detached horizontally from the front or vertically from the top. The gears are reliably engaged and disengaged from the drive gears of the drive without interfering with each other.

The process cartridge 30 is the apparatus main body I.
When removed further, the flexible shield member 18 stored in the lower portion of the photosensitive belt 1 slides along the photosensitive belt 1 by the urging force of an elastic member (not shown) to cover the transfer area, It also protects the exposed photosensitive surface. The elastic member is stored by mounting the process cartridge 30 on the apparatus main body I, and the shielding member 18 is stored in the position shown in FIG. 1 again to open the transfer area of the photosensitive belt 1.

[0032]

According to the present invention, by utilizing the space occupied by the exposure optical system, the work such as replenishment of the developer and replacement of the image forming member can be carried out very easily from the upper portion of the apparatus main body. As a result, it is possible to provide a color image forming apparatus which is compact and has excellent workability in maintenance.

[Brief description of drawings]

FIG. 1 is a cross-sectional configuration diagram showing a first embodiment of a color image forming apparatus of the present invention.

FIG. 2 is a cross-sectional configuration diagram showing an opened state of the device.

FIG. 3 is a sectional configuration diagram showing a second embodiment of the device.

FIG. 4 is a cross-sectional view of a main part of each of the devices.

FIG. 5 is an explanatory view showing a layout of a drive system of the process cartridge.

[Explanation of symbols]

 1 Photoconductor Belt 4 Charging Device 5 Laser Writing System Unit 6, 7, 8, 9 Developing Device 10 Cleaning Device 11 Fixing Device 12 Transfer Roller 13 Paper Feed Cassette 14 Tining Roller 15 (Paper Ejection) Tray 16 Waste Toner Box 30 Process Cartridge 40 Manual feed tray 50A, 50B Opening 51A, 51B Shielding plate I Device body II Top lid III Side door A, B Container

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI Technical display location G03G 15/01 Z 15/08 8004-2H 112 9222-2H

Claims (3)

[Claims] 1. A color image forming apparatus in which a plurality of developing devices are arranged in parallel around an image forming body, and an optical path of an exposure optical system for performing image exposure on the image forming body is arranged on an upper surface of the plurality of developing devices. The color image forming apparatus is characterized in that the developer is replenished to the developing device or the image forming member is attached and detached across the optical path. 2. The color image forming apparatus according to claim 1, wherein the image forming member is an image forming body or a developing device. 3. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is capable of opening an upper portion of an apparatus main body, and the optical path of the exposure optical system is shielded and protected when the lid is opened.