JPH0389367A - Color image forming device - Google Patents

Abstract

PURPOSE:To eliminate trouble in carrying paper by bringing transfer paper fed from a paper feed cassette arranged on a plane level with an upper case front surface part in close contact with a transfer belt so as to be carried to a photosensitive drum transfer part. CONSTITUTION:The front surface of an upper case 1 is provided with the loading part of the paper feed cassette C positioned almost horizontally in an open condition and a paper feed means A which separates one transfer paper from the loaded paper feed cassette C and feeds it to a transfer carrying means 50. In this case, after a pretransfer electrifier 9 electrifies a multicolor toner image to make it easy-to-transfer, the already rotated pretransfer carrying means after transfer starts, that is, the transfer belt 50, is brought into contact with the photosensitive drum 30, and the multicolor toner image is transferred onto a recording paper fed from the paper feed cassette C via a paper feed roller 12 being a paper feed means provided on the upper case 1 at the timing of when an image is formed. Consequently, a carrying route with a degree of freedom in arrangement, which is readily handled and hard to develop trouble, can be designed.

Description

Detailed Description of the Invention [Industrial Application Field] The present invention has a color process cartridge in which a plurality of developing means containing multicolor developers and an image carrier can be detachably installed in an apparatus main body. The present invention relates to a compact and lightweight electrophotographic color image forming apparatus, and particularly to a color printer with a compact structure.

[Background of the invention]

There are many ways to obtain color images using electrophotography.
A device has been proposed. For example, Japanese Patent Publication No. 61100770
As disclosed in the publication, a latent image is formed and developed on a photoreceptor drum according to the number of separated colors of the original image, and each time the development is performed, the latent image is transferred onto the transfer drum to form a multicolor image on the transfer drum. There is a method of forming a color copy and then transferring it onto recording paper to obtain a color copy. In addition to the photoreceptor drum, the device using this method has one
It is necessary to provide a transfer drum that is large enough to transfer images for each sheet onto its circumferential surface, and the device inevitably becomes large and has a complicated structure.

In addition, a latent image is formed on the image carrier using a dot exposure scanning writing system such as a semiconductor laser or an LED, and furthermore, a COD
, a-3i, and other solid-state image pickup devices, which perform so-called digital color image processing, have been proposed in Japanese Patent Application Laid-open No. 61-73977, but none of them are mentioned above. This is causing a similar problem.

Another method is to repeatedly form a latent image on a photoreceptor drum in accordance with the number of separated colors of an original image and develop it with color toner, and then layer color powder on the photoreceptor drum and then transfer it to obtain a color image. The basic process of forming a multicolor image is disclosed in Japanese Patent Application Laid-open Nos. 60-75850 and 60-76766 by the present applicant.
No. 60-95456, No. 60-95458, No. 60-158475, etc.

In a multicolor image forming apparatus that obtains a color image by such superimposition, a plurality of developing units containing different color toners are arranged around the periphery of the photoreceptor drum. Generally, the photoreceptor drum is rotated multiple times,
A color image is obtained by developing the latent image on the photosensitive drum.

On the other hand, regarding the structure of general copying machines, the
As disclosed in Japanese Patent No. 8-54392, a proposal has been made in which a photosensitive drum, a developer, and a cleaner are integrally attached to a support member to facilitate replacement and repair of each unit.

In addition, as a small and simple monochrome compatible device that can be easily handled by general users, there is a device that is integrated with these devices and configured in a disposable format.
It is disclosed in Japanese Patent No. 54255.

Furthermore, Japanese Patent Laid-Open No. 147366/1983 discloses a printer that incorporates a laser writing system into a similar device.

Furthermore, as an apparatus for forming mono-color or full-color images, a disposable single-color process cartridge and a (color) cartridge containing multiple developing units, which are also disposable, can be exchanged, as described in Japanese Patent Application Laid-open No. A multicolor image forming apparatus disclosed in Japanese Patent No. 58-72159 has been proposed, but it is not easy to operate, small, and inexpensive, and does not necessarily provide a satisfactory image to the user when reproducing color images. This has not yet been achieved.

Furthermore, the present applicant has previously disclosed in Japanese Patent Application Laid-Open No. 63-293563 various replacement forms such as a single color cartridge and a color cartridge having multiple developing units, and also disclosed a cartridge that can be inserted and removed from the main body of the apparatus. Patent application No. 62-2344 for a color image forming apparatus provided with a pedestal on which a photoreceptor drum, multiple developing devices, cleaners, etc. can be attached and detached.
No. 93 and No. 62-239748, etc., however, there is a lack of ease of use for users due to an imbalance in the lifespan of consumables such as toner and developer stored in multiple developing units, and internal mechanisms are The device is complicated and large in size, and it has not been possible to provide a compact and inexpensive device, and there remains a major problem that leads to loss of users.

In particular, the above-mentioned publication disclosing the disposable cartridge adopts a structure in which the disposable process cartridge can be replaced in the upper housing with a two-part structure, and attempts to solve the problems of cartridge replacement workability and jam clearing. . In addition, we focused on making it easier to replace the process cartridges, mainly replenishment toner cartridges and cleaning cartridges for recovered toner, by dividing the process cartridge into two parts and placing the process cartridge in the lower housing to improve maintenance work efficiency. This is disclosed in Japanese Unexamined Patent Publication No. 1161/1983.

[Problem that the invention seeks to solve]

However, in a color process cartridge in which the multiple developing devices and the image carrier are replaceable with respect to the main body of the device, it is easy to load and unload the cartridge into the main body of the device, and the toner or image carrier from the multiple developing devices There is no need to worry about developer leakage or spillage, especially when dealing with transfer material jams.
No compact color printer has been proposed that has a color process cartridge that does not have these problems.

In particular, Japanese Patent Laid-Open No. 58-1980 has a structure in which a disposable cartridge is provided in the upper casing with a two-part structure that facilitates the above-mentioned jam handling.
72159, etc., a process cartridge is provided in the lower casing to facilitate replenishment and replacement of collected toner, and the process cartridge for developing, cleaning, photosensitive drums, etc. is lifted upward when handling jams. The structures described in JP-A-58-1161 conflict with each other in terms of workability for replacement and ease of jam removal.Furthermore, since these process cartridges have paper feeding and conveyance systems at the bottom, it is difficult to replace process cartridges and equipment. Even if the cartridge is tightly sealed to prevent toner from spilling due to external vibrations and shocks to the main body, toner may spill from the developing device or cleaner section, causing stains inside the machine and on the transfer paper. child .

On the other hand, as a configuration capable of avoiding such structural defects, a printer as shown in FIG. 6 is disclosed in Japanese Utility Model Application Laid-open No. 63-195357. The printer also has a built-in process cartridge and has a flat feeding path at the top, but at the same time that the transferred toner image surface is facing downward, it is fixed from the transfer material separating section of the photoreceptor drum 101. The problem of the conveyance unit has not been solved due to the limitation of the conveyance path leading to the section 102, and the ease of clearing jams when dividing into two and the overall compactness due to the upstand stack feeding configuration. In particular, the opening angle of the upper housing is restricted when the upper housing is divided into two parts using the shaft 103 as a fulcrum, so that it is not possible to provide a device with excellent operability for the user.

JP-A No. 64-40850 and JP-A No. 63-24, which should solve similar problems of conveyance and jam handling, respectively.
Although there are disclosures such as Japanese Patent No. 4059, all of them lack compactness and ease of use, including the paper feed cassette and space.

Particularly in color copying, the area around the photoreceptor drum inevitably tends to become larger, and various methods have been devised to reduce the space around the drum by rotating or moving the positions of the multiple developing units required for color image formation. However, it is not possible to reduce the diameter of the drum, and as the drum diameter increases, the separation performance deteriorates, so there is a need for a separation mechanism and process, securing space, and in conjunction with this, the drum transfer/separation position. The lack of a conveying process between the fixing unit and the fixing unit, especially when the transfer paper falls from the paper feed unit 4A or 4B due to gravity and is conveyed, becomes a major problem.

Furthermore, in forming a color image by the overlapping process, a drum circumferential length corresponding to at least the maximum image width (the short diameter is acceptable) is required, so the above-mentioned problem related to increasing the drum diameter becomes a particularly important problem.

The present invention has been developed to solve the various problems mentioned above.

[Means for solving problems]

The above purpose is to provide a developer group including an image bearing drum and a charger, a color toner developer, and a black toner developer on its periphery;
It has a cleaning device and a transfer paper transfer means,
In a color image forming apparatus that can be opened into two parts (upper and lower), the upper housing has a transfer belt as a transfer conveyance means, and a paper feed cassette that is opened and located almost horizontally on the top surface of the upper housing. This is achieved by a color image forming apparatus characterized by having a mounting section and a paper feeding means for separating one copy of transfer paper from the mounted paper feeding cassette and feeding the paper to the transfer conveyance means.

〔Example〕

An embodiment of the present invention is shown in FIGS. 1 to 5.

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

The printer has a clamshell structure divided into an upper housing 1 containing a transfer belt and an apparatus main body 2 corresponding to a lower housing containing color process cartridges. It can be held open at a predetermined angle by a hinge connected to the main body 2, and in the closed state, it is integrated with the device main body 2 by a stopper.

A photosensitive drum 30, which is an image forming body constituting the image forming section of the printer. One developing device 36, 37, 38, 39 containing yellow, magenta, cyan, and black developers, and a cleaning device 4 having a pressure release mechanism for the image forming body.
In addition, each component of the charger 35 is housed in an integrated color process cartridge 3 to form a unit.

The unitized process cartridge 3 has a second
As shown in the figure, by opening the upper case l, it is vertically inserted into the device main body 2 from above, and the bottom holder is inserted into the base 4.
After being placed in the storage position, it is fixed at the storage position by the action of a pressing member (not shown) that is interlocked with the closing lid of the upper housing l.

In the process cartridge 3, the developing units 36, 37, 38, and 39 are distributed to the left and right with respect to the center line of the photosensitive drum 30, that is, the developing units 36, 37, 38, and 39 are separated from each other by the axis of the photosensitive drum 30. 37 is arranged symmetrically on the right side, and developing units 38 and 39 are arranged symmetrically on the left side, and furthermore, the respective developing sleeves of the developing units 36 and 37 arranged on the right side are arranged clockwise and on the left side. The developing sleeves of the developing devices 38 and 39 are rotated counterclockwise to develop the respective images.

By arranging the developing device group in this manner and further rotating the developing sleeve in the opposite direction, the process cartridge 3 has a balanced left-right balance in terms of weight and power transmission mechanism, and is easy to handle. Further, generation of harmful vibrations is also prevented.

In addition, it is possible for the developing units placed in symmetrical positions on the left and right sides to have the same structure, and the toner can be scraped off from the developing sleeve after the developing action is completed extremely efficiently due to the action of gravity. This has the advantage that a suitable amount of fresh toner can always be supplied.

On the other hand, a toner collection box 47 is installed at a symmetrical position of the cleaning device 40 with respect to the photosensitive drum 30 to improve the left and right weight balance of the process cartridge 3. The toner collection box 47
A toner transport pipe 49 containing a toner transport screw 48 is installed between the blade 4 and the cleaning device 40 at the front of the process cartridge 3.
The waste toner peeled off from the surface of the photoreceptor drum 30 by 0A is conveyed by the thrust of the toner conveying screw 48 and collected into the toner collecting box 47 .

Further, since each developing device is maintained with its opening closed upward, the developer does not leak out and fall or get mixed into other developing devices.

The printer has a laser writing system unit B in a space on the side of the process cartridge 3, and a recording paper conveying surface in a part above the process cartridge 3 that spans both the upper housing 1 and the main body 2 of the apparatus. We have set up
The photosensitive drum 30 is subjected to laser scanning by the laser writing system unit B from diagonally downward, and a color toner image formed by superimposing the scanning surface is transferred onto the lower surface of the recording paper.

The process of color image copying 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 color image data input section (Fig. 3 (a)) where the image sensor scans the original image.
) is processed by an image data processing unit equipped with a computer (Fig. 3 (b)) to create image data, which is then stored in the image memory (Fig. 3 (c)). Stored. Then, the image memory is taken out during recording and stored in the recording section (
For example, the color image forming apparatus shown in FIG. 1 is inputted as shown in FIG. 3(d)).

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, the laser writing system unit B outputs a laser beam generated by a semiconductor laser (not shown). is rotated and scanned by a polygon mirror 32 rotated by a drive motor 31, the optical path is bent by a mirror 34 via an fθ lens 33, and the peripheral surface of the photoreceptor drum 30 is charged in advance by a charger 35 serving as a charging means. It is projected upward and forms a bright line.

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

That is, the photosensitive drum 30 is charged again by the charger 35, and then the second
The color signal is input to the writing system unit B, and writing is performed on the drum surface to form a latent image in the same manner as in the case of the first color signal described above. The latent image is developed by a developer 37 loaded with magenta (M) toner as a second color.

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

A developing device 38 has cyan (C) toner, and forms a cyan (C) toner image on the drum surface based on a control signal generated by a signal processing section.

Furthermore, 39 is a developing device having black toner, and a black toner image is superimposed and formed on the drum surface by the same process. Direct current or even alternating current bias is applied to each sleeve of these developing units 36, 37, 388 and 39, and jumping development is performed using a two-component developer serving as a developing means, and the photoreceptor whose base is grounded is Development is performed on the drum 30 without contact.

The color image thus formed on the circumferential surface of the photoreceptor drum 30 is re-charged by the charger 9, and then transferred from the paper feed cassette C horizontally mounted on the upper surface of the upper housing l to the paper feed roller and the paper feed guide in the transfer section. The image is transferred to the bottom of the recording paper sent through the process.

That is, after this multicolor toner image is charged by the pre-transfer charger 9 to be easily transferred, the transfer conveyance means, that is, the transfer belt 50, which has been rotating since the start of transfer, is brought into contact with the photosensitive drum 30, and the paper feed cassette is transferred. The image is transferred from C to a recording paper fed through a paper feeding roller 12 and a timing roller 13, which are paper feeding means also provided in the upper housing l, in synchronization with the image formation.

The structure of the transfer belt 50 is such that an elastic layer with a thickness of 0.5 mm is provided on the outer periphery of a comb belt containing conductive cloth as a base, and an insulator layer (dielectric layer) with a thickness of 50 μm is further provided on the outer periphery. Rollers 60a; 60b, 60c
The transfer belt 50 comes into contact with or separates from the photosensitive drum 30 as the tension roller 60a is driven to rotate and the roller 60b moves up and down. The transfer belt 50 is charged by a transfer device 51, and the surface of the transfer belt 50 is charged with 1.5KV to 3.5KV. Transfer is performed by applying a transfer charge having a polarity opposite to that of the toner of about OKV.

On the other hand, the photosensitive drum 3 with the recording paper separated from the drum circumferential surface
At 0, the blade 40A of the cleaning device 40 comes into contact to remove the remaining toner, and after that is finished, it is pulled away from the drum surface again and a new color image format process begins.

In this way, the recording paper is conveyed horizontally over the top of the process cartridge 3, and the transfer surface is also facing downward, so even if the toner spills or scatters from the cleaning device 40 or the like, the image surface will be contaminated. I never get to the point where I do it. Note that the recording paper that has undergone the transfer is ejected to the outside via a fixing roller 80 and a paper ejection roller 90.

As is clear from the above description, in the color image forming apparatus of the present invention, the paper feed cassette C is mounted on the upper surface of the upper casing L, making it easy to handle the paper feed and at the same time provide a free conveyance route. It is also possible to construct a gentle conveyance path without causing troubles such as jams.

Furthermore, since all of the installed paper cassettes C are locked in a horizontal position, there is no risk that the paper cassettes C will move or fall even if the opening angle of the upper housing l is widened. This means that the upper casing 1 can be opened until it can be easily taken out.

Furthermore, as shown in FIG. 5 showing the top surface of the color image forming apparatus, if the vertical paper feed section A including the timing roller 13 is configured to be able to be opened and closed in the horizontal direction as shown by the dashed line, the process Since the toner collection box 47A provided separately from the cartridge 3 can be taken out of the apparatus main body 2 together with the feeding section A, the toner collection box 47A can be made larger accordingly.

Further, the color image forming apparatus of the present invention can have a structure in which the upper housing is opened to the back of the main body of the apparatus, thereby making it possible to easily replace, for example, a replenishment toner cartridge.

Figure 5 shows the right side of the device, and Figure 5 (A
) is an example in which the upper housing kA is opened sufficiently wide with respect to the apparatus main body 2A, and the toner cartridge 71A connected to the supply hopper 70A is pulled out upward.

FIG. 5(B) shows a structure in which the replenishment hopper 70B can be tilted slightly to the left from an upright position when not in use.
This is an example in which the toner cartridge 71B can be pulled out only by opening the upper housing IB at a small angle.

FIG. 5(C) shows an example in which the toner replenishment section is provided on the left side, that is, on the front side of the main body 2C of the apparatus. In this case, the toner cartridge 71G can be easily pulled out regardless of the opening angle of the upper housing 1C. This is a possible and most desirable example.

[Effects of the Invention] As explained above, according to the present invention, the transfer paper fed from the transfer paper storage section or cassette disposed on a surface substantially parallel to the top surface of the upper housing is brought into close contact with the transfer belt. The paper is then conveyed to the photoreceptor drum transfer section, and in particular, problems occur when conveying the paper to the photoreceptor drum transfer section in conventional U-turn paper feeding (normally, the transfer paper is folded at a steep angle and thrown tightly into the transfer section,
In addition, paper feed conveyance speed and photoreceptor speed must be synchronized when the transfer paper is in close contact with each other (jam troubles, transfer misalignment, etc.) are not caused, and when the transfer paper is conveyed after toner transfer, the lower The transfer paper with the toner image on it is transported by the suction force of the transfer belt, and is also transported to the fixing section by separation at the curvature section, making it possible to transport the paper from the bottom regardless of the distance between the photoreceptor drum and the fixing section. Moreover, since the transfer belt part of the upper case can be separated and opened as a transport part, it is easy to clear jams, and when replacing process cartridges, etc., the transfer paper storage cassette can be held in a bag-like state on the upper case. The opening angle is sufficient to at least allow the drum and/or developing process cartridge to be pulled out to the top without causing the cassette or transfer paper to fall out. Furthermore, by using a transfer belt, it became possible to have a conveyance section and its opening at the top, so that the paper feed conveyance section and the development section for the transfer paper The inner guide side plate in the feeding and conveying section leading to the transfer belt can be attached to the transfer belt, transfer paper cassette, etc. in line with the opening of the upper housing, without causing any crumbling or staining after toner transfer or during replacement maintenance. It is now possible to open the door in one piece, making it extremely easy to deal with troubles such as jam handling.

As described above, according to the present invention, recording paper is fed in the same way as during normal horizontal conveyance, and separation from the photoreceptor after image transfer is reliably performed, so that conveyance troubles are extremely reduced, and the cassette storage section can be made compact in the main body. A highly practical color image forming apparatus that can be installed and that can easily handle jam removal and maintenance and inspection of various process equipment has been provided.

[Brief explanation of drawings]

1 and 2 are cross-sectional configuration diagrams of the color image forming apparatus of the present invention, FIG. 3 is a perspective view showing the image forming system, FIG. Fig. 6 is an explanatory diagram of each opening/closing method of the upper case related to the present invention.
Examples of split-type image forming devices from other companies. 1, IA, IB, IC...upper housing 2.2A
, 2B, 2C...Device main body 3.3A, 3B, 3G...Process cartridge 9.
...Pre-transfer charger 30...Photosensitive drum 35...Charger 36.3
7.38.39...Developer 40...Cleaning device 47.47A...Toner collection box 50...Transfer belt 51...Transfer devices 70A, 70B...Replenishment hoppers 71A, 71B...・Toner cartridge A...Paper feed section B...Racer writing system unit C, CA, C B, C C...Paper feed cassette

Claims (2)

[Claims] (1) It has an image bearing drum and a charging device, a group of developing devices including a color toner developing device and a black toner developing device, a cleaning device, and a transfer paper transfer means on its periphery, and can be opened into two parts, upper and lower. In a color image forming apparatus that
The upper casing has a transfer belt as a transfer conveyance means, and the upper surface of the upper casing has a mounting part for a paper feed cassette that is open and located almost horizontally, and a part for loading transfer paper from the mounted paper cassette. 1. A color image forming apparatus comprising a sheet feeding means for separating sheets into sheets and feeding the sheets to the transfer conveying means. (2) The image carrier drum is provided in a lower casing, a developing unit group is provided below the image carrier drum, and a process cartridge including at least the image carrier drum and the developing unit group is provided with an opening. 2. The color image forming apparatus according to claim 1, wherein the color image forming apparatus is capable of being attached to and detached from the apparatus main body in the vertical direction.