JPH0375667A - Color image forming device - Google Patents

Abstract

PURPOSE:To improve quality of a color image by loading a transfer drum to an upper box body, releasing the upper box body so that a multiple number of processing units can be unloaded individually from the upper direction, and facilitating exchange of an image forming mechanism in terms of units. CONSTITUTION:The device is of a so called clam shell structure where a lower box body 1 and the upper box body 2 are able to be divided into halves. A transfer drum 50 is loaded to the upper box body 2 and that upper box body 2 is released so that the multiple number of processing units can be individually unloaded from the upper direction. That processing unit consists of a cleaning unit, an image carrying unit, and a developing device unit, and the developing unit is placed so that it wraps around the bottom surface of an image carrying drum in this unit against the image carrier unit. Thus, a color image of high image quality can be stably fed which is easily attachable/detachable and exchangeable, making it superior in its maintainance.

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 Unexamined Patent Publication No. 123257/1983.

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 becomes large and complicated.

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, in the color image forming apparatus described in Japanese Patent Application Laid-open No. 57-72159, since a plurality of thin developing devices are provided in a horizontally stacked manner, the developer in the developing devices can be stirred and mixed, and Frictional charging tends to be insufficient, and color mixing of toners tends to occur between developing devices that are in instant contact, resulting in a decrease in the quality B and resolution of color images. Furthermore, since the transfer means including the transfer drum is disposed 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 a decrease in image quality, etc. However, since process cartridges for color image formation contain multiple developing devices, they are more complex and larger than process cartridges for black and white image formation, and they do not allow the main body of the apparatus to come into contact with other image forming equipment. Safely removing and reinstalling the device 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 upper housing and a lower housing, the lower housing is equipped with a plurality of process units for forming images, and the upper housing is equipped with a transfer drum. This is achieved by a color image forming apparatus, wherein the plurality of process units can be individually taken out from above by opening the upper housing.

Further, in a preferred embodiment of the present invention, the plurality of process units include a cleaning unit, an image carrier unit, and a developing unit, and the developing unit is configured to handle the image in the unit with respect to the image carrier unit. This is achieved by a color image forming device arranged to wrap around the underside of the carrier drum.

The color image forming apparatus of the present invention has a so-called clamshell structure that can be divided into two parts, a lower housing and an upper housing. The lower housing includes an image carrier unit that integrates an image carrier drum, a pre-transfer charger, and a charger that applies a negative charge to the drum, a cleaning device, a waste toner recovery device, and a connection therebetween. Yellow (Y) is a cleaning unit that is integrated with a waste toner transport pipe that transports waste toner.

A developing device unit that integrates a plurality of developing devices filled with developer for each color of magenta (M), cyan (C), and black (BK) and a toner replenishing device for the developing devices is incorporated.

However, the unitization of the image forming member is not limited to the above example; for example, the cleaning device and the waste toner recovery device may be made into separate units, or the cleaning unit and the image carrier unit may be integrated into a unit. You can also use it as

The developer used in each developer of the developer unit includes a two-component developer mainly composed of magnetic toner and a two-component developer composed of non-magnetic toner and a magnetic carrier. It is preferable to use two-component development, which has excellent color tone reproduction.

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.

I; Since the outer periphery of the image carrier drum can be made into a so-called demand type in which the outer circumference is smaller than the length of the transfer paper in the feeding direction, in that case, the image carrier drum can be made with a small diameter of 100 mm or less; The image forming equipment provided on the outer periphery can be made smaller and lighter, and the apparatus can be made more compact.

The transfer drum is arranged obliquely above the image carrier drum due to the structure of the apparatus. That is, in relation to the image forming process, image forming equipment such as a cleaning device, a charging device, a writing device, and a plurality of developing devices are arranged biased to the right side and below the image bearing drum. It is placed diagonally above and offset to the left. When the degree of deviation of the transfer drum to the left side is expressed as an inclination angle θ0 of a plane passing through the image carrier drum axis and the transfer drum axis with respect to a horizontal plane passing through the image carrier drum axis, it is usually 10°≦θ. ≦80
0, preferably 20°≦θ≦70°.

In addition, in the transfer method using the transfer drum, the transfer paper conveyed in advance from the paper feed cassette is wound and fixed onto the transfer drum by mechanical means such as a gripper, electrostatic adsorption means, etc. The toner images of each color formed on the drum are transferred onto a transfer paper in an overlapping 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.

By the way, in order to take out the process unit housed in the lower housing, the upper housing is opened upward by 30" to 906" using the hinge provided at one end of the lower housing as a fulcrum, and the lower housing and upper housing are removed. A space necessary for taking out the process unit is formed between the two, and the process is performed using this space.

Incidentally, the process unit is housed in the order of the developing unit, the image carrier unit, and the cleaning unit from the bottom on the support stand provided in the lower housing, and is removed in the reverse order.

Note that in the lower housing of the color image forming apparatus of the present invention, writing means for writing color data onto the image carrier drum together with the process unit is provided in close proximity.

Further, the developer unit includes Y, M, C, and BK color developers as well as a toner replenishment device that replenishes toner to the developer group, and the developer group and the toner replenishment device are integrated as a unit. will be exchanged.

Since the color image forming apparatus of the present invention has the above configuration, when the image forming equipment is damaged, deteriorated due to fatigue, materials are consumed, etc., the function can be easily restored by replacing the unit, and as a result, high image quality can be maintained for a long period of time. It is believed that a stable supply of

〔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 7 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, and FIGS. 3 to 5 are perspective views of each process unit housed in the lower housing. FIG. 6 is a diagram showing the arrangement of each image forming device, and FIG. 7 is an image forming time chart.

In the printer of this embodiment, a plurality of process units for image formation are housed in a compact manner, and a lower housing l has a writing device B to an image bearing drum, while an upper housing has a transfer drum 50. A casing 2 is provided so as to be openable about a hinge 1a.

In addition to the transfer drum, the upper housing includes a paper feed cassette 7.
5, paper feed system C including paper feed roll 76, transport roll 77, timing roll 78, etc. and transport rolls 80.82.
A paper ejection system including a first fixing roll 83, a guide 84, a paper ejection tray 85, etc. is attached.

When the upper housing 2 is opened upward as shown in Fig. 2, it becomes possible to check for poor wrapping of the transfer paper in the transfer area, poor transfer, etc., and the open space of the upper housing 2 relative to the lower housing l can be This makes it possible to take out the plurality of process units from above.

Here, the plurality of process units in this embodiment housed in the lower housing l include a cleaning unit 11, an image carrier unit ■, and a developing unit II+, and first, the developing unit ■ is fixed to the lower housing l. It is supported on a support stand 45, 46 and cented. Next, the cleaning unit (2) is similarly supported by the substrate and set on the developing unit (2), the image carrier unit (2) is also supported by the substrate, and the cleaning device 40 and waste toner recovery device 70 of the cleaning unit I are set.
It is set so that it is sandwiched between.

FIG. 3 shows the structure of the cleaning unit I, in which a cleaning device [40 denotes a toner collection box 70 placed between the image bearing drum 30 and a pair of front and rear relay plates 40a as shown with dashed lines, for example. The toner conveying tube 70a is installed between the toner conveying tubes 70a and the toner conveying tubes 70a are connected to the toner conveying tubes 70a, so that they can be handled as an independent unit.

FIG. 4 shows the structure of the image carrier unit (2), in which the image carrier 30 has a charger 35 disposed facing its circumferential surface.
and the pre-transfer charger 9 are integrated, for example, via a pair of front and rear support plates 30a indicated by dashed lines, and are treated as an independent unit similar to the cleaning unit I.

On the other hand, FIG. 5 shows the developing device unit (2), in which toner supply boxes 36a to 39a for each developing device are mounted and supported on the front surface of each integrated developing device, and the cleaning unit I and the image forming unit (2) are supported. It is also supported by the front and rear substrates as an independent process unit similar to the above.

Note that the relay plate 40a and the support plate 30a may have shapes or forms other than those shown in the drawings from the viewpoint of structure or handling.

By the way, in order to take out each of the process units from the lower casing 1, first remove the engaging metal fitting 86 provided at one end of the upper casing 2.
a from the protrusion 86b of the lower case l, and remove the upper case l.
is opened upward by 60 degrees, and the unit side wall is attached to the lower housing l.
The image carrier drum shaft 30a is aligned with the guides 47a (47b) and 48a (48b) at the four corners of the front substrate 42a and rear substrate 42b provided on the inner wall of the
7b) while sliding the cleaning unit [・■
, image carrier unit (2), and developer unit (2) are pulled upward in this order and removed from the apparatus.

Further, in order to mount each of the process units in the lower housing l, it is sufficient to accommodate them in the reverse order through the guide portions of the substrate.
8a (28b) on the inner surface of the substrate.
b) It is set by being placed on top; at the same time as it is stored, it is connected to the drive system and power source on the lower housing 2 side, and functions as a process unit for image formation.

Here, the developer unit I [each developer 36, 37 of I]
38 and 39 are integrated so that adjacent developing units share the wall surface of the housing, and are arranged so as to wrap around the lower surface of the image carrier drum. Also, developing rolls 36a and 37a
.

38a and 3Qa are vertically arranged with the openings facing upward.

In addition, 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 bearing 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 units 36 and 39 are arranged on the right side.
By rotating each of the developing sleeves 7 clockwise and the developing sleeves of the developing devices 38 and 39 disposed on the left side counterclockwise, the developing action of each image is performed. There is.

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 emotions is also prevented.

In addition, each developing unit 36, 37°3 is placed at a symmetrical position on the left and right.
8 and 39 can each have the same structure, and the toner scraping off from the developing sleeve after the development is completed is extremely efficient due to the action of gravity, so that a proper amount of fresh toner is always available. Can supply toner.

In this embodiment, as described above, each developer in the developer unit (2) has a built-in toner replenishment device, so that toner is continuously replenished as the toner in the developer is consumed, and the toner is scraped off by the cleaning device. Since the waste toner is constantly collected by the waste toner recovery device 70 via the waste toner transport pipe 70a, image formation cannot be continued until the developer carrier deteriorates due to fatigue or the image carrier deteriorates due to fatigue. I can do it.

Next, using the color printer configured as described above, image formation in this example was performed in the following manner.

Note that in an apparatus that uses the transfer drum 50 to form a color image by a transfer method each time, it is possible to perform image formation as a so-called demand type by using an image carrier drum with a small diameter of 172 mm, for example, the diameter of the transfer drum. In this embodiment, since the image bearing drum has the same diameter as the transfer drum, as shown in the timing chart described later,
They were rotated together synchronously five times to form a color image.

First, during the 100 rotations 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 200 is applied by the Y signal, which is the first video signal. The modulated laser light thus obtained was introduced into laser writing unit B.

In the unit B, a polygon mirror 32 rotated by a high-speed rotation motor 31 scans, collimating lens 33a1 reflecting mirrors 34a, 34b, 34c,
The laser beam passes through the f-theta lens 33b with a diameter of 100 m.
A Y electrostatic latent image was formed on the image bearing drum 30 of m. This electrostatic latent image is developed by a non-contact, reversal development method by a Y developer 36 containing a two-component developer and having a DC component of 1,600 V and an AC component of 3 KHz and a developing bias of 500 V applied. A Y toner image was formed on the carrier drum 30.

This Y toner image was transferred onto the transfer paper on the transfer drum rotating in synchronization with the image carrier drum 30 by wrapping the transfer paper fed from the paper feed cassette 75. Incidentally, the transfer paper fed from the paper feed cassette 75 and fed via the timing roll 77 in accordance with the image forming timing of the image carrier drum 30 is charged on its surface by the charger 62 in advance. Gripper 7 on transfer drum 50
9 and the solenoid pressure bonding member 64, the winding was fixed mechanically and electrostatically. Further, the Y toner i on the image bearing drum 30 is transferred to the transfer drum 5 by the action of the transfer pole 66 which is driven at the same timing by the electrode driver 65.
0 transfer paper. The residual toner on the surface of the image bearing drum after the transfer was cleaned by the action of the cleaning device 40.

After the image carrier drum 30 and the transfer drum 50 are charged by the charger 35 during the second rotation, a laser beam modulated by the M video signal is written on the drum 30, and M development is performed in the same manner as before. A M toner image was formed due to the development using a device. 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 bearing drum 30 and the transfer drum 50, the C I- formed on the drum 30 based on the C video signal and the BK video signal.
The toner image and the B K l'' toner image were transferred onto the Y toner image and the M toner image on the transfer paper of the drum 50 to form a color toner image. The transfer paper is released and separated by the separating claw 68, and then transported to the first fixing roll by the transport roll 80, where it is fixed and a color image is formed. and was discharged onto the paper discharge tray 85.

FIG. 6 shows the relative position of each image forming device in each process unit shown in FIGS. 1 to 5 with respect to the image carrier 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. In the cleaning unit (2), the waste toner removed from the image carrier drum 30 and collected in the collection section of the cleaning device 40 is transferred to a waste toner transport pipe 70afa installed on the back side of the image carrier unit. Waste toner collection device 7 of the unit I
It was recovered to 0.

The waste toner transport pipe 70a includes a flexible waste toner transport screw 70 that is rotated by the power system of the lower housing 1.
The waste toner was conveyed to the waste toner collection device 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 20,000 times, the upper housing 2 was opened, each process unit was taken out from the lower housing 1, and only the developer unit 2 was replaced to continue image formation. After 80,000 color prints, all process units were replaced in preparation for the next image formation. As a result, high-density, clear color prints were consistently obtained from start to finish.

Although a color printer has been described in this embodiment, it may also be a color copying machine equipped with a color scanner.

〔Effect of the invention〕

As is clear from the above description, according to the color image forming apparatus of the present invention, a plurality of process units made up of distributed image forming equipment are housed in the apparatus in a freely insertable and removable manner. Since the forming equipment can be easily replaced unit by unit, the quality of color images is guaranteed, and the equipment is smaller and lighter, and the talam shell structure makes it easier to remove jams. It is played.

[Brief explanation of drawings]

1 and 2 are cross-sectional views explaining the configuration of a color printer according to an embodiment, FIGS. 3 to 5 are perspective views of each process unit, and FIG. FIG. 7, which is a diagram showing the arrangement configuration, is an image forming time chart. 1...Lower housing 2...Upper housing 9...
Pre-transfer charger 30...image carrier 36, 37, 3
8.39...Developer 40...Cleaning device 5
0...Transfer drum A...Video signal B...
・Writing device C... Paper feeding system D... Paper ejection system ■... Cleaning unit

Claims (3)

[Claims] (1) It is divided into an upper housing and a lower housing, and the lower housing is equipped with a plurality of process units that perform image formation,
A color image forming apparatus, wherein a transfer drum is attached to the upper housing, and the plurality of process units can be individually taken out from above by opening the upper housing. (2) The color image forming apparatus according to claim 1, wherein the plurality of process units include a cleaning unit, an image carrier unit, and a developing unit. (3) The color image forming apparatus 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. .