JPH0380265A - Color image forming device - Google Patents

Abstract

PURPOSE:To obtain a device excellent in maintenance and checking and to stably supply a high-definition color image by preferentially and easily attaching/ detaching image forming materials that are frequently maintained and checked as a unit and replacing the unit. CONSTITUTION:The device is divided into a device main body 1 and an upper enclosure 2 which can be opened. Process units 30 and 36 to 39 and a transfer drum 50, all of which are used for image formation, are loaded on to the device main body 1. In the case of opening the upper enclosure 2, the process units 30 and 36 to 39 and the transfer drum 50 can be removed to the upside of the loaded device main body 1. Consequently, the image forming material requiring maintenance can be easily replaced as a unit, whereby the quality of a color image is secured. Moreover, the miniaturization of the device and the reduction in weight are achieved.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention provides a color image forming apparatus using a transfer drum and having a clamshell structure having a lower housing and an upper housing that is openable to the lower housing. In particular, the present invention relates to a color image forming apparatus in which image forming equipment is divided into a plurality of units, the plurality of units can be taken out individually to improve maintenance performance, and the apparatus is made more compact and jam removal is facilitated.

[Conventional technology]

Conventional color image forming devices using transfer drums include:
For example, there is Japanese Patent Application Laid-Open No. 61123257.

In this publication, a document image is read, and a laser beam is modulated using the obtained digital signal to write on an image carrier to form an electrostatic latent image, which is then developed using a rotary color developer. A color image is formed by sequentially overlapping, transferring and fixing toner images of each color onto a transfer paper wound around a transfer drum.

In this device, an image carrier drum, a rotary developing device, a transfer drum, etc. are each independently incorporated into the device.
The equipment is large and complex.

For example, Japanese Patent Application Laid-open No. 58-72159 discloses a transfer drum type color image forming apparatus having a color process cartridge that integrally incorporates an image bearing drum, a charger, a plurality of developing devices, a cleaning device, etc. Proposed.

In this case, the image forming equipment is housed in a process cartridge that can be inserted into and removed from the apparatus, and can be replaced depending on the usage limit, making it possible to stabilize the quality of color images and improve the performance of the apparatus. Smaller size and lighter weight are realized.

[Problem that the invention seeks to solve]

However, since none of the color image forming apparatuses described in the above-mentioned publications have a divided structure, there are problems such as troublesome parts replacement and jam removal.

In particular, when replacing the transfer drum, an extra space is required between the transfer drum and the image carrier drum, and positioning during installation is difficult, causing transfer misalignment and color misalignment.

In particular, in the color image forming apparatus described in the above-mentioned Japanese Patent Application Laid-Open No. 57-72159, since a plurality of thin developing devices are provided in a horizontally stacked manner, the agitation and mixing of the developer in the developing devices and the resulting friction Charging tends to be insufficient, and toner color mixing tends to occur between adjacent developing units, resulting in a decrease in the quality and resolution of color images. Furthermore, since the transfer means including the transfer drum is arranged below the image bearing drum, the cleaning device, and the plurality of developing devices, it is easily contaminated by toner leakage from the cleaning device and the developing devices, resulting in deterioration of image quality, etc. The negative effects of this will occur.

By the way, process cartridges for color image formation contain multiple developing units, making them more complex and larger than process cartridges for black and white image formation. , reinstalling it is not an easy task. This is especially troublesome for devices that include a transfer drum.

Furthermore, in the process cartridge described in Japanese Patent Application Laid-Open No. 57-72159, equipment that is not subject to maintenance must be removed from the apparatus and disposed of or replaced, which is not desirable from the viewpoint of operability and economy.

[Means for solving problems]

(Objective of the invention) Image forming equipment that requires frequent maintenance and inspection can be prioritized as a unit, and can be easily attached/detached and replaced, making it easy to maintain, stably supplying high-quality color images, and being compact and lightweight. It is an object of the present invention to provide a color image forming apparatus.

(Structure of the Invention) The above-mentioned object is divided into an apparatus main body and an upper casing that can be opened to the apparatus main body, and the apparatus main body includes a plurality of process units for image formation and an upper housing of the units. This is achieved by a color image forming apparatus which is equipped with a transfer drum having the structure shown in FIG.

According to a preferred embodiment of the present invention, the plurality of process units include an image carrier unit, a developer unit, and a transfer drum or a transfer drum unit, and the developer unit is located within the unit relative to the image carrier unit. This is achieved by a color image forming device disposed so as to cover the lower surface of the image carrier drum.

In the color image forming apparatus of the present invention, an upper casing is attached to the main body of the apparatus, which has a writing device for writing color data onto an image carrier drum, and a plurality of individually removable process units and a transfer drum. It is openable and has a so-called clamshell structure.

The plurality of process units that are removably housed in the apparatus main body include, for example, an image bearing drum, a pre-transfer charger, a charging electrode that applies a certain charge to the drum, a cleaning device, and a waste toner recovery device. an image carrier unit that includes an image bearing unit; and a developer unit that integrally includes a plurality of developers filled with yellow (Y), magenta (M), cyan (C), and black (BK) color developers. . Further, a transfer drum unit that is integrated with the transfer drum or equipment around the transfer drum is incorporated in the apparatus main body above the process unit.

Note that the plurality of process units are not limited to the configuration described above, and for example, the image carrier unit may be divided into an image carrier unit consisting of an image carrier drum, a charger, and a charging electrode, a cleaning device, and a waste toner. It is also possible to form a cleaning unit that integrates the collection device and the waste toner transport pipe that connects them. Furthermore, the toner replenishing device may be incorporated into the apparatus main body as an independent unit, or may be integrated with each developing device as a developing device unit, or the toner replenishing device may be installed outside the apparatus main body. Alternatively, a toner transport pipe having a built-in screw conveyor may be provided to supply toner to each developing device in the main body of the apparatus. Further, the developing devices may be integrated so as to share a wall surface, or may be independent developing devices adjacent to each other.

The developer used in each developer of the developer unit includes a single-component developer containing magnetic toner as a main component and a two-component developer consisting of non-magnetic toner and a magnetic carrier. It is preferable to use a two-component developer that has excellent image color tone reproduction.

Next, each of the process units and the transfer drum or transfer drum unit can be individually taken out of the apparatus and replaced using the space formed between the upper housing and the apparatus main body when the upper housing is opened. That is, in the color image forming apparatus of the present invention, there is no need to replace the image forming equipment all at once, and only the equipment that requires replacement for maintenance needs to be taken out and replaced as a unit, which is advantageous from the viewpoints of operability and economy. °It is.

Next, in the present invention, a transfer drum is used as the transfer means,
Each time a Y, M, C, BK color toner image is formed on the image carrier drum, it is transferred onto a transfer paper fixed to the transfer drum, and a color toner image is formed and fixed on the transfer paper to form a color image. An image is formed. In this image forming method,
For example, it does not use a special image forming method as described in Japanese Patent Application Laid-open No. 60-76766, and has the advantage that image formation can be performed by a process similar to a normal black and white image forming method.

In addition, it is possible to use a so-called demand type in which the outer circumference of the image carrier drum is smaller than the transfer paper length in the feeding direction, so in that case, it is possible to reduce the size and weight of the image forming equipment provided on the outer circumference of the image carrier drum. , compactness of process units and equipment is achieved.

The transfer drum is arranged obliquely above the image carrier drum due to the structure of the apparatus. In other words, due to the image forming process, the image forming equipment including a cleaning device, a charging electrode, a writing device, and a plurality of developing devices are arranged biased to the right side and below the image bearing drum, so that the transfer drum is located on the right side of the image bearing drum. It is placed diagonally upward and off to the left. When the degree of deviation of the transfer drum to the left side is expressed by the inclination angle θ0 of the plane passing through the transfer drum axis of the image carrier, it is usually lO0≦θ≦80°, preferably 20′≦θ≦70°. Ru.

In addition, as a transfer method using the transfer drum, the transfer paper conveyed in advance from the paper feed cassette is wrapped and fixed on the transfer drum by mechanical means such as a gripper, electrostatic adsorption means, etc. The toner images of each color formed thereon are transferred onto the transfer paper in a superimposed manner each time to form a color toner image on the transfer paper. The transfer paper carrying the color toner image is separated by a separation means such as a separation claw, and then transported and fixed to a fixing device by a transport roller or the like to form a color image.

Next, in order to mount each equipment unit on the apparatus main body, a front board and a rear board having mounting plates for mounting the equipment units on the front and rear inner surfaces of the apparatus main body are provided in advance, and the upper When the housing is opened, the equipment units can be stored in order from the lower equipment unit to the upper equipment unit. In other words, when the upper case is opened, the space formed between it and the main body of the device is utilized.
First, the developing unit is placed and housed on, for example, a placement plate provided at the bottom of the substrate. Next, the image carrier unit is placed and housed on a placement plate provided at the middle stage of the substrate, and finally, the transfer drum (or transfer drum unit) is placed and housed on a placement plate provided at the top stage of the substrate. Each time each equipment unit is placed and stored on the mounting plate, the position may be set by engaging with the mounting plate or with each other, but preferably when the upper housing is closed. It is preferable that each piece of equipment is positioned by being pressed against its respective mounting plate.

At the same time as each equipment unit is stored, a gear is provided on the image carrier drum shaft in the image carrier unit and connected to a drive source gear, and the gear on the image carrier drum shaft is connected to the developing device, transfer drum, etc. It is activated by being connected to a gear attached to the shaft.

Since the color image forming apparatus of the present invention has the above configuration, damage to the image forming equipment, fatigue deterioration, wear and tear, etc. 4.
Functional recovery can be easily achieved by replacing the unit, and as a result, it is possible to stably supply high-quality color images.

〔Example〕

EXAMPLES The present invention will be specifically explained below with reference to Examples, but the embodiments of the present invention are not limited thereto.

1 to 8 are diagrams for explaining this embodiment, and the first
The figure is a sectional view of the printer of this embodiment when the lid is closed, FIG. 2 is a sectional view of the printer when the lid is opened, FIGS. Figure 6 is a sectional view taken along the line x-x in Figure 1 to explain the support mechanism when each image forming device is housed in the apparatus body, Figure 7 is a diagram to explain the arrangement of each image forming device, and Figure 8 is a It is an image formation time chart.

In the printer of this embodiment, in addition to the image carrier unit (2), the developer unit (2), and the transfer drum unit (2), there is a lower part 81b of the writing device B1, the paper feeding system C1, and the fixing device 81. An upper housing 2 having an upper part 81a and a paper ejection system is provided so as to be openable about a hinge la as a fulcrum.

When the upper housing 2 is opened upward, each of the unit materials can be easily taken out in units by utilizing the space formed between the upper housing 2 and the main body 1 of the apparatus.

FIG. 3 shows the mechanism of the transfer drum unit (2), in which the transfer drum 50 and the transfer pole 63 are connected and supported by a support plate 50a, and the transfer drum 50 is charged and the transfer paper is electrostatically charged to the drum 50. Charger 65 for winding the target
, the separation claw 66 and the presser 64 are connected and supported by the relay plate 50b, and the support plate 50a and the relay plate 50b
are connected by connecting plates 51a and 51b to form an integrated transfer drum unit.

Next, FIG. 4 shows the configuration of the image forming unit I, in which a cleaning device 40 and a waste toner collecting device 17 are connected to each other by a toner transport pipe 70a (see FIG. 1).
0 is supported by the relay plate 40a. On the other hand, the image carrier drum 30, the pre-transfer charger 9, and the charging electrode 35 are connected to the support plate 3.
The cleaning device 40. Waste toner collection device, image carrier drum 30. The pre-transfer charger 9 and the charging electrode 35 are integrated into an image carrier unit.

Furthermore, FIG. 5 shows the developing device unit (2), and as mentioned above, each developing device has an integrated housing and can be handled as an independent unit in the same manner as the above-mentioned units. Further, the developer unit (2) includes color toner replenishing devices 36a, 37a for stably supplying each color toner to the Y, M, C, BK developing devices 36, 37, 38, 39 that constitute the unit (2).
, 38a, and 39a are connected via a toner supply pipe (not shown).

To mount each of the unit materials to the main body 1 of the apparatus, the upper housing is opened at 45 degrees, and the developing device i-knit 2 is inserted from above as shown in FIG. 6. Note that a front substrate 42a and a rear substrate 42b are provided on the front and rear inner surfaces of the apparatus main body l, and the transfer drum shaft 5 is attached to the front substrate 42a in advance.
1a, a vertical groove is provided for dropping the image carrier drum shaft 31a, and the rear substrate 42b also has a transfer drum shaft 51b, an image carrier drum shaft 31b, a developing unit rotation shaft 37b (36b, 3
8b, 39b) are provided.

The developing device unit IF is placed on the bottom mounting plate 42c through the vertical groove, and the developing devices 37 and 38 are projected downward through square holes provided in the bottom mounting plate 42c.

Next, the image carrier unit (2) is stored. At this time, the drum shafts 31a, 31b are dropped through the vertical grooves and placed on the front mounting table 32a1 and the rear mounting table 32b.

Next, the drum shafts 51a and 51b of the transfer drum unit (2) are also dropped through the vertical grooves, and placed on the front mounting table 32a1 and the rear mounting table 32b. After each equipment unit is stored in the main body of the apparatus, the upper housing 2 is closed, the engaging member 87a is engaged and locked with the protrusion 87b, and the mutual position of each equipment unit is set, and vibrations during work are set. It is fixed in such a way that it does not move or become misaligned.

At the same time as each equipment unit is mounted, the image carrier drum 30
The rotating shaft 51b is connected to a power shaft provided on the back surface of the rear substrate 42b through gear engagement.

By the way, each developer 3637 in the developer unit Sendai.
Adjacent developing units 38 and 39 are integrated by sharing the wall surface of the housing, and are arranged so as to wrap around the lower surface of the image bearing drum. Also, a developing roll 36a.

The openings on the sides 37a, 38a, and 39a face upward, and are arranged vertically.

Further, in a state in which the developing units 36, 37, 38, and 39 are distributed to the left and right with respect to the center line of the image carrier drum, that is, the developing units 36 and 37 are on the right side with respect to the axis of the drum 30. In addition, the developing units 38 and 39 are arranged at symmetrical positions on the left side, and furthermore, the developing sleeves of the developing units 36'' and 37 placed on the right side are moved clockwise, and the developing units 36'' and 37 placed on the left side are arranged in symmetrical positions. By rotating each of the developing sleeves 38 and 39 counterclockwise, the developing action of each image is performed.

By arranging the developing device group in this manner and also by rotating the developing sleeve in the opposite direction, each of the process units has a well-balanced left-right balance in terms of weight and power transmission, making it easy to handle. The occurrence of harmful vibrations is also prevented.

In addition, each developing device is placed at a symmetrical position on the left and right.
8.39 can have the same structure, and the toner scraping off from the developing sleeve after the developing action is done extremely efficiently due to the action of its weight, so that a proper amount of fresh toner is always available. Can supply toner.

In this embodiment, as described above, each developing device in the developing device unit is equipped with a toner replenishing device, and as the toner in the developing device is consumed, the toner is continuously replenished and the toner is scraped off by the cleaning device. Waste toner is constantly transported through the waste toner transport pipe 7.
Since the waste toner is collected by the waste toner collection device 70 via 0a,
Image formation can be continued until the developer carrier deteriorates due to fatigue or the image carrier deteriorates due to fatigue.

Next, this example was carried out as follows using the color printer having the above configuration.

By the way, in an apparatus that uses the transfer drum 50 to form a color image by a transfer method every time, for example, 1/2 of the transfer drum diameter is used.
By using a small-diameter image carrier drum, the so-called demand type J-1 can be used to shave 2 to 4 times, but in this embodiment, the image carrier drum diameter is the same as the transfer drum diameter. As shown in the timing chart to be described later, they were rotated five times in synchronization to form a color image.

First, during the first rotation of the image carrier drum 30, a charge of -700V is applied to the drum by the charger 35, and then a laser beam from the semiconductor laser device lOO is applied by the first video signal signal of the video signal A. was modulated, and the obtained laser light was incident on laser writing unit B. In the unit B, the laser beam is scanned by a polygon mirror 32 that is rotated at high speed by a motor 31, and is scanned by a collimating lens 33a, reflecting mirrors 34a, 34b, 3
4c, the image carrier drum 30 with a diameter of 100 mm was irradiated through the f-θ lens 33b, and an electrostatic latent image was formed on the drum.

This latent latent image is developed by a non-contact, reversal development method by a Y developing device 36 containing a two-component developer and to which a developing bias of 1500 V for the DC component and 3 IZ, 1 KV for the AC component is applied. Y toner is placed on the image carrier drum 30 (iPA#) -1f-, f/7'l't/l, -
J--a+-)k#-hJF-The image was transferred onto a transfer paper fed from the door 5 and fixed to the transfer drum 50. By the way, the transfer paper is sent out from the paper feed cassette 75 by a paper feed roll 76, and then transferred to the transfer drum 50 via a conveyance roll 77 and a timing roll 78 in accordance with the timing of forming a toner image on the image bearing drum 30. Supplied.

The gripper 61 of the transfer drum 50 is driven by the drive device 62 to clamp and fix the leading edge of the transfer paper, and is electrostatically attracted to the transfer drum 50, which has been charged in advance by the charger 65, and is then conveyed. . The presser 64 is used to evenly wrap the transfer paper around the transfer drum 50. The Y toner image is transferred onto the transfer paper conveyed together with the transfer drum 50 by a transfer pole 63 driven by a drive device 62.
The transfer paper carrying the Y toner image is transferred by the action of t; the separation claw 66, the charger 65, and the presser 64 are inactivated;
In this state, it was rotated to receive the next color toner image transfer. Note that the cleaning blade 40 of the image carrier drum 30
Image formation was performed with the lens a kept "on" from beginning to end.

After the image carrier drum 30 and the transfer drum 50 are charged by a charger 35 during the second rotation, a laser beam modulated by an M video signal is written on the drum 30,
The M toner image was developed by the M developing device in the same manner as the previous time. This M toner image is transferred to the transfer drum 50, which is rotated in synchronization with the image carrier drum 30 with the separating claw 68 released, overlapping the Y toner image on the transfer paper whose winding is fixed. The residual toner on the surface of the image bearing drum 30 was cleaned by the cleaning device 40 and charged by the charger 35. Next, during the third and fourth rotations of the image carrier drum 30 and the transfer drum 50,
Based on the C video signal and the BKC video signal,
The C toner image and BK toner image formed on Muco 0 were transferred to overlap the Y toner image and M toner image on the transfer paper of the drum 50 to form a color toner image. The transfer paper carrying the color toner image was separated by the separation claws 66 after the gripper 61 was released, and was transported by the transport roll 80 to the fixing roll 82 and fixed thereon to form a color image. After the fixation, the transfer paper was discharged to a paper discharge tray 86 via transport rolls 83 and 84 and a guide 85.

FIG. 7 shows the relative positions of each image forming device in each process unit shown in FIGS. 1 to 6 with respect to the image carrier and the drum 30.

In the figure, it is assumed that the image carrier drum 30 rotates clockwise, and the rotational phase at the end of cleaning is set as a reference position S, and the positions of each piece of equipment in the clockwise rotational direction are shown at angular intervals.

In this case, the processes of charging, latent image formation, toner image formation, transfer, and cleaning of residual toner will proceed according to the time chart shown in FIG. The overlapping transfer, separation, cleaning, etc. of the toner images of each color on the transfer drum were completed, and one cycle was completed. The image carrier unit
In -I, the waste toner removed from the image carrier drum 30 and collected in the collecting section of the cleaning device 40 is transported to the waste toner transport pipe 70a installed on the back side of the image carrier unit I; Waste toner collection device 70 of the unit I-I
was recovered.

The waste toner transport pipe 70a includes a flexible waste toner transport screw 70 that is rotated by the power system of the apparatus main body l.
b is built in, and the waste toner is conveyed to the waste toner recovery device 70 by the propulsive force generated by its rotation.

In this example, considering the fatigue of the carrier in the developer,
Every time color printing was performed 10,000 times, the upper housing 2 was opened, the developer unit (2) was taken out from the main body 1 of the apparatus, and image formation was continued while replacing it. The image carrier unit (2) was replaced after 60,000 color prints, and all process units were replaced after 10,000 prints in preparation for subsequent image formation.

As a result, high-density, clear color prints were obtained throughout.

〔Effect of the invention〕

As is clear from the above description, according to the color image forming apparatus of the present invention, since a plurality of process units each consisting of image forming equipment are removably housed in the apparatus, images required for maintenance can be easily removed. Since the forming equipment can be easily replaced unit by unit, quality assurance of color images is ensured, the device is smaller and lighter, and the clam-shell structure makes it easier to remove jams. The effect is produced.

[Brief explanation of drawings]

1 and 2 are cross-sectional views explaining *g of the color printer of the embodiment, FIGS. 3 to 5 are perspective views of each process unit, and FIG. A diagram illustrating a storage configuration using the board,
FIG. 7 is a diagram illustrating the arrangement of each image forming device with respect to the image carrier drum, and FIG. 8 is an image forming time chart. l...Device main body 2...Upper housing 9...
Pre-transfer charger 30...image carrier drum 36.3
7, 38, 39...Developer 40...Cleaning device 42a...Front board 42b...Rear board 32a, 32b, 42c, 52a,
52b... Placement plate 50... Transfer drum I.
・・Image carrier unit ■・Developer unit ■・
...Transfer drum unit A...Video signal B
...Laser writing device C...Paper feeding system D...Paper ejection system

Claims (3)

[Claims] (1) It is divided into an apparatus main body and an upper housing that can be opened to the apparatus main body, and the apparatus main body is equipped with a plurality of process units for image formation and a transfer drum arranged above the units. A color image forming apparatus, wherein the plurality of process units and the transfer drum can be taken out above the apparatus main body when the upper housing is opened. (2) The color image forming apparatus according to claim 1, wherein the plurality of process units include an image carrier unit including at least an image carrier drum and a cleaning device, and a developer unit including a plurality of developers. (3) Color image formation according to claim 1 or 2, wherein the developing device unit is arranged with respect to the image carrier unit so as to cover the lower surface of the image carrier drum in the unit. Device.