JPH02140768A - Color picture forming device - Google Patents

Abstract

PURPOSE:To make a device small and compact by overlapping and forming plural developed pictures on a picture carrier through the sequential use of plural developing units and transferring them onto transfer material in a single action. CONSTITUTION:Plural developing units 31Y, 31M and 31C are employed in order to form plural overlapped pictures on the picture carrier 11, which are transferred onto the transfer material in a single action. Since the developing units 31Y, 31M and 31C are designed to be flat and are followed by a developing sleeve 313 performing development in a direction and a toner containing part 310 opposite to the sleeve 313, the multistage piled developing units 31Y, 31M and 31C can be arranged almost in parallel with each other. Consequently, they can be disposed in one developing unit and can be produced into a compact process cartridge together with a photosensitive drum 11.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a color image forming apparatus using electrophotography, and more particularly, to a color image forming apparatus that is miniaturized, has improved maintenance performance, and has improved jam processing performance. .

[Conventional technology]

An electrophotographic image forming apparatus that forms full-color or monochrome images includes a charger that charges a photoreceptor drum, an image exposure unit that exposes an image to the photoreceptor drum, and a developer that develops the electrostatic image on the photoreceptor drum with toner. A transfer device that transfers the toner image on the photoreceptor drum onto recording paper is disposed around the photoreceptor drum.

Of these, when using yellow (Y), magenta (M), and cyan (C) toner, an electrophotographic image forming apparatus for full-color images has three or four developing units each containing black (BK) toner. During the three rotations of the photoreceptor drum, yellow (Y),
Magenta (M), cyan (C), sometimes black (BK)
A full-color image is obtained by forming each toner image on a photoreceptor drum and transferring this toner image onto recording paper. When using such an image forming method, the color image forming apparatus can be made compact by making three or four developing units thin and arranging them close to each other.

Japanese Unexamined Patent Publication No. 61-55661 proposes a color image forming apparatus using such an image forming method, in which latent images are formed by three lasers corresponding to three developing devices, and the photosensitive drum and developing device are connected to each other. The container and the cleaning means are integrated into a unit and can be taken out from the main body of the device. Also, JP-A-61-55
In the color image forming apparatus described in Publication No. 661,
Although this contributes to improving maintainability, it is easy for developer to spill or get mixed in when the unit is inserted or removed.

Furthermore, Japanese Patent Application Laid-open No. 72159/1984 describes an example in which the photosensitive drum and its surroundings are formed into a unit in a color image forming apparatus that uses a transfer drum to transfer each color toner image to a recording paper.

[Problem that the invention seeks to solve]

However, in the color image forming apparatus described in JP-A-58-72159, (1) the image forming section extends not only around the photosensitive drum but also to the transfer drum.

(2) The circumferential speed and gap between the photosensitive drum and the transfer drum must be maintained with high accuracy.

(3) A release mechanism is required to take out the photoreceptor drum.

As mentioned above, in a color image forming apparatus using a transfer drum, not only is the mechanism complicated and expensive as described in (2) and (3) above, but also the mechanism is complicated and expensive, as is the case with a monochrome image forming apparatus that does not require a transfer drum. Image forming means are not concentrated around the photoreceptor, and the advantages of unitizing the image forming section (process unit) cannot be fully obtained.

The present invention improves maintainability by integrating the developing unit, the image bearing member, and the cleaning means, or by forming a cartridge structure in which all three are integrated and the remaining one is independently insertable and removable. When a scale and multiple developing devices are assembled into a unit and the unit is inserted or removed from the main body of the apparatus, especially when the developing unit is inserted or removed, the developer may spill outside or the developer may leak into other developing devices. It is an object of the present invention to provide a color image forming apparatus which has a structure that prevents the mixing of recording paper, and which facilitates jam handling when a conveyance failure of the conveyed recording paper occurs.

Still another object of the present invention is to reduce the size of the color image forming apparatus by a process of forming a composite toner image such as a color toner image made of toners of multiple colors on the surface of a photoreceptor drum and transferring the same to a transfer paper all at once. In addition, in order to make it compact, image forming means such as a plurality of developing devices and cleaning means are concentrated around the photoreceptor drum, and in particular, each developer is placed approximately flat on one side of the periphery of the photoreceptor drum. Load and arrange as shape. On the other hand, since the developing unit side consisting of a plurality of developing devices is heavy, it is an object of the present invention to provide a color image forming apparatus in which the opening direction of the upper casing of the main body is set in a direction with excellent operability.

[Means for solving problems]

The above object is to provide a developing unit including a plurality of developing devices each having a developer of a different color, an upper housing having a rotatable image carrier, and a cleaning means, and a lower housing.
The sides of the plurality of developing units facing the image bearing member are arranged such that the side facing the image bearing member of the plurality of developing devices is arranged such that the side facing the image bearing member of the plurality of developing devices is centered on an axis parallel to the rotation axis of the image bearing member and arranged near the side wall of the main body on the side of the developing unit with respect to the rotation axis. The developing unit, the image bearing member, and the cleaning means may be inserted and removed integrally, or three of them may be integrated and the remaining one independently. Cartridge configuration: When forming an image with multiple colors, multiple developing devices are used sequentially to form a color developed image in which multiple developed images are superimposed on the image carrier, and the color developed image is transferred onto the transfer material at once. This is achieved by a color image forming apparatus that performs image transfer.

〔Example〕

The color image forming apparatus according to the present invention has a so-called Talam shell structure that can be divided into two parts, an upper housing and a lower housing, and the process members for forming a color image are attached to the housing as a unit. Prior to the explanation, an overview of process-related components and operations will be explained. FIG. 1(a) is a schematic configuration diagram showing a first embodiment of a color image forming apparatus of the present invention.

In the figure, 11 is a photoreceptor drum which is an image carrier having a photoconductor layer made of organic semiconductor or the like, and 12 is a charger that uniformly charges the surface of the photoreceptor drum 11 rotating in the direction of the arrow.

A document placed on the platen glass 21 (not shown)
However, the image data of the document read by the image reading device 22 is supplied to the laser exposure device 23 after being subjected to image processing. The laser exposure device 23 irradiates the photoreceptor drum 11 with image light modulated based on the image data of the document, and this image light creates an electrostatic charge on the surface of the photoreceptor drum 11 that is uniformly charged by the charger 12. A latent image is formed.

This electrostatic latent image is generated by a first developing device 31Y having a yellow (Y) color developer provided in the developing unit 30, a second developing device 31M having a magenta (M) color developer, and a cyan CC' ) A toner image is formed on the surface of the photoreceptor drum 11 by a third developing device 31C having a color developer.

13 is a transfer material supply means; 14 is a transfer device that transfers the toner image formed on the photoreceptor drum 11 onto the transfer material sent by the supply means 13; and 15 is a transfer material onto which the toner image has been transferred, which is exposed to light. a separator for separating from the body drum 11;
Reference numeral 6 indicates a conveying means for sending the separated transfer material to the fixing device 17, 18 indicates a paper discharge plate for receiving the transfer material to which the toner image has been fixed by the fixing device 17, and 19 indicates a portion remaining on the photoreceptor drum l to which the toner image has been transferred. A pre-cleaning static eliminator 20 is used to remove residual toner from the photosensitive drum 11.
It is a cleaning device that removes from the surface of.

The color image forming apparatus of the first embodiment includes a process cartridge 40 that includes at least a photosensitive drum 11, a developing unit 30, and a cleaning device 20, and the process cartridge 40 has an engaging portion provided on its outer wall surface. 40a, 40b, and 40c are respectively engaged with support arms 140a, 140b, and 140c provided on the main body 100 side, and are locked by locking means (not shown). Developing devices 31Y, 31M, 31C in the developing unit 30
forms a developer layer thinner than the gap between the developing sleeve and the photoreceptor drum 11 on the developing sleeve of these developing devices and transports the developer layer, and the toner is ejected from the developer layer to form an electrostatic image on the photoreceptor drum 11. Developing under non-contact developing conditions allows the toner image to be developed without disturbing the toner image previously formed on the photoreceptor drum 11, and switching between a developing state and an inactive state is applied to the developing sleeve. This is preferable because it can be easily done by switching the bias voltage, etc., and there is no need to move the developing device when switching.

A developing device 31Y installed inside the developing unit 30.

The main bodies of 31M and 31G have a thin structure, and the second developing device has an inter-track structure and is arranged approximately parallel to the photosensitive drum 11, and is compactly unitized. FIG. 2 shows the developing device 31Y.

In FIG. 2, inside the developing device 31Y, a toner storage device 310, a stirring impeller 311. A stirring impeller 312, a developing sleeve 313, a magnet roll 314, and a toner supply roller 315 are provided. A lid portion 319 is provided on the top of the developing device 31Y, and covers the internal toner storage device 310, stirring impeller 31L, stirring impeller 312, developing sleeve 313, magnet roll 314, and toner replenishment roller 315, thereby removing toner. Prevents scattering. Note that the gap between the developing sleeve 313 and the photosensitive drum 11 is maintained by a roller (not shown) that is provided coaxially with the developing sleeve 313 and contacts the photosensitive drum 11.

Toner T is stored at the bottom of the toner storage device 310,
The toner T is scooped up toward the upper left in FIG. 2 by rotating the wiper plate 310a clockwise.

The toner T scooped up by the wiper plate 310a is moved to the left in FIG. 2 by the rotation of the toner supply roller 315, and is supplied to the stirring impeller 311. The stirring impeller 311 stirs the magnetic carrier and the toner T together with the stirring impeller 312, and as the stirring impeller 312 rotates counterclockwise, a two-component developer consisting of the magnetic carrier and the toner T is applied to the developing sleeve 313. Make it adhere. Inside the developing sleeve 313 is a magnet roll 314 having a fixed magnetic pole, and the developing sleeve 313 and the magnet roll 314 constitute the above-described magnetic brush containing the developer.

A thin layer of developer is formed on the surface of the developing sleeve 313 by the magnetic brush described above, and the thickness of this thin layer is thinner than the gap between the developing sleeve 313 and the photoreceptor drum. For example, the developer thin layer forming means 3 such as a magnetic cylindrical rod provided opposite to the magnetic pole of the magnet roll 314
17 is pressed against the developing sleeve 313, the developer layer is shaped into an even thin layer. From the surface of the thin layer of developer, the toner T is transferred to the photoreceptor drum 11 by an alternating current bias.
The electrostatic latent image formed on the surface of the photoreceptor drum 11 is developed to obtain a toner image.

During this development, a bias voltage consisting of a direct current component and an alternating current component is applied to the developing sleeve 313, and by controlling the bias voltage as described later, variations in developing conditions between the developing devices are adjusted. I try to do that.

Figure 3 shows developing units 31Y, 31M, 31 inside.
A cross-section of the developing unit 30 is shown, and the developing unit 30 constitutes a part of the process cartridge 40. The developing unit 30 is a housing having an opening on the side of the photoreceptor drum 11, and a guide member 39 consisting of a roller or the like is provided inside. The developer sleeve 313 is pressed toward the photoreceptor drum 11 by an elastic member 32 provided behind the developer and urged toward the photoreceptor drum 11, so that the set distance between the developing sleeve 313 and the photoreceptor drum 11 is maintained.

In addition to the photosensitive drum 11, the developing unit 30, and the cleaning device 20, the process cartridge 40 is equipped with a charger 12 and a pre-cleaning static eliminator 19 in this embodiment. Further, when a separation claw is used to assist in separating the transfer material from the photoreceptor drum 11, this separation claw is also attached. A motor serving as a drive source for the process cartridge 40 is provided in the main body 100, and when the process cartridge 40 is attached to the main body 100, power is transmitted and electrical connection is made through a coupling or the like. Of course, a motor serving as a driving source may be provided in the process cartridge 40. In this case, the process cartridge 40 may be attached to the main body 100 and electrically connected to the main body 100.

When the image reading device 22 reads a document placed on the platen glass 21, color separation is performed via the filter 9. The filter 9 is, for example, a fourth filter.
As shown in the figure, filter 9R.

Filter 90. Consisting of a filter 9B and a filter 9ND, the filter 9 is used when reading a document.
R, filter 9G, filter 9B, filter 9N
Reading is performed after passing any one of D. To select which of the filters 9R, 9G, 9B, and 9ND is selected, the filter 9 is moved in the left-right direction in FIG. This is achieved by In addition, filter 9R
, filter 9G, and filter 9B are filters that pass red light, green light, and blue light, respectively, and Filter 9ND is a neutral filter that passes all three color lights.

When the 40 process cartridges are installed in the main body 100, the detection member 141 (FIG. 3) detects the cartridge 40.
The mark 41 attached to the sensor is detected and inputted to the CPU 60 by the control circuit shown in FIG. In the developing unit 30, developing devices 31G and 3111.31Y containing cyan (C), magenta (M), and yellow (Y) toner are located at predetermined positions, so that the photoreceptor drum 11 is Yellow (Y), magenta (M) for each rotation.

Each cyan (C) toner image is sequentially formed on the photoreceptor drum il by image light irradiated onto the photoreceptor drum 11 by the laser exposure device R4.

The toner image formed in this manner is transferred by a transfer device 14 onto recording paper (not shown) supplied from a paper feeding device 13. The transferred toner image is heated and fixed in a fixing device 17, and after being fixed, it is discharged outside the machine.

In developing with each toner, the filter 9 is selected in accordance with the developing device to be operated.

That is, in FIG. 5, the determination result of the process cartridge determination circuit 60 from the detection member 141 is supplied to the CPU 61. In FIG. In response to this determination result, the CPU 61 issues a command to the image reading device 22. That is, when developing the developing device 31C with cyan (C) toner, the filter 9
R issues a command for the filter 9G to perform development in the developing device 31M with magenta (M) toner, and for the filter 9B to perform development in the developing device 31Y with yellow (Y) toner, and the filter selection circuit 2
2a filter settings are made. The developing device in the process cartridge 40 is cyan (C) and magenta (M).
, yellow (Y), and may include black (BK) or other combinations. By differentiating the marking portion 41 according to the color of the developer in the process cartridge 40 and the combination thereof, filter settings corresponding to this are automatically made, and color copying is performed.

In the color image forming apparatus having the functions described above, the process cartridge 40 of this embodiment is attached to the upper housing 102 and has two parts that can be opened and closed with respect to the lower housing 101.
What's going on with the split structure? FIG. 1(b) shows the upper housing 102.
It shows the open state. In the color image forming apparatus of the present invention, the lower housing 101 and the upper housing 102 are connected to the photosensitive drum 11 by the developing device 31Y.

A hinge 103, which is the center of opening and closing, is provided parallel to the axis of the photoreceptor drum 11 near one end surface on the side where 31M and 31C are located. Further, on the other side facing the hinge 103, an opening/closing fitting 104 is provided spanning the upper casing 102 and the lower casing. The opening/closing fitting 104 is unlocked and the upper housing 102 is opened by lifting it clockwise in the figure. Between the lower casing 101 and the upper casing 102, there is a balancing member (not shown) made of a biased spring member or the like and a locking member, so opening the upper casing 102 in the clockwise direction in the drawing does not require much force. The open state is held by the locking member, and the open state is maintained even if the hand is released.

In this embodiment, the process cartridge 40, which includes the photosensitive drum 11, the cleaning device 20, and the developing unit 30 on the left and right sides thereof, is attached to the upper housing 102, so that the process cartridge 40 moves upward when opened and moves in parallel. The developing devices 31Y and 31M were located.

31C, the developing sleeve 313 corresponding to the opening is in an upward position, and at the same time, the toner storage device 310 is located on the lower side.

Engagement portion 40 provided on the outer wall surface of the process cartridge 40
a, 40b, and 40c are engaged with and supported by rail-shaped support arms 140a, 14Qb, and 140c provided on the upper housing 102, respectively, so that the process cartridge 40 cannot be pulled out in a direction perpendicular to the plane of the paper, that is, in a horizontal direction. It can be taken out. At this time, the developing devices 31Y, 3
Since the 1M and 3IC are oriented upward, when the process cartridge 40 is removed and installed, the shock does not cause the developer to spill out or get mixed into other developing devices. Further, a transfer paper supply means 13, a transfer device 14, a separator 15 serving as a separation electrode, a transfer material conveyance means 16, and a fixing device 17 are arranged in the lower housing 10.
1, the conveyance path for the transfer material is exposed by opening the upper housing 102 upwards, and jam removal when a transfer paper failure occurs can be easily cleared by directly inserting the transfer material. be able to.

Figures 6(a) and 6(b) show the second embodiment, which has the same functions as the first embodiment, but
In this embodiment, the photoreceptor drum 11, which is an image carrier, and the cleaning device 20 are unitized into an integrated process cartridge 240, and the developing device 31Y,
31M and 31C can be inserted and removed independently from the developing unit 230 attached thereto. The process cartridge 240 has an engaging portion 240a provided on its outer wall surface,
240b, 240c are rail-shaped support arms 140a, 140b, 140c provided on the upper housing 102.
and are locked by locking means (not shown).

On the other hand, a developing unit 230 housing developing devices 31Y, 31M, and 31C in the same manner as in the first embodiment is installed in a unit garage 232 that can be inserted and removed in a direction perpendicular to the plane of the drawing. The unit garage 232 is rotatable about a pivot shaft 231 as a rotation center. A spring member biased counterclockwise may be provided around the rotation shaft 231 if necessary.

FIG. 6(a) is a block diagram in an operating state, and since the center of gravity of the unit garage 232 with the developing unit 230 installed is on the left side of the pivot shaft 231 in the diagram, the unit garage 232 is moved counterclockwise. , the stopper 140d provided on the upper housing 102 comes into contact with a locking portion 232d provided on the unit garage 232, and its position is regulated.
The internal developing devices 31Y, 31M, and 31C are pressed by elastic members 32 to respective development positions set with respect to the photosensitive drum 11.

FIG. 6(b) shows the opening/closing fitting 104 from the state of FIG. 6(a).
The figure shows a state in which the door is unlocked and the upper housing 102 is opened. When the upper housing 102 is lifted clockwise, the center of gravity of the unit garage 232 with the developing unit 230 attached moves to the right side of the pivot shaft 231 in the figure, and the unit garage 232 is separated from the photoreceptor drum 11. It rotates clockwise and comes into contact with a stopper pin 132 provided on the upper housing 102. In such an open state, the developing units 31Y, 31M, and 3iC are in a more upward position than in the first embodiment, and the developer does not fall out or get mixed in. Furthermore, since the photosensitive drum 11 and the developing units 31Y, 31M, and 31C are located apart from each other, the process cartridge 240 and the developing unit 2
30 can be inserted and removed independently when in the open state.

FIG. 7 shows a third embodiment, which has the same functions as the first embodiment, but in this embodiment, a photosensitive drum 11 and developing devices 31Y, 31M, and 31G are installed. The developing unit 30 is an integrated process cartridge 340, which can be inserted and removed independently from the cleaning unit 320 having the cleaning device 20.

FIG. 7 shows a state in which the upper housing 102 is opened.

The process cartridge 340 is provided with engaging portions 340a and 340b provided on its outer wall surface, and engages with rail-shaped support arms 140a and 140b provided on the upper housing 102, respectively, so that when the upper housing 102 is open, It can be taken out in the direction perpendicular to the page (towards the front of the device). The cleaning unit 320 is a housing having a U-shape in cross section, and the pre-cleaning static eliminator 19 and the cleaning device 2o are located inside the cleaning unit 320.
In the operating position, the retaining part 320a provided on the outer wall of the cleaning unit 320 is regulated in position by the stopper 120a provided on the upper housing 102, and is activated. holding position. Therefore, when the upper housing 102 is open,
Release the stopper 7 pa 102a and remove the cleaning unit 32.
0 can be rotated counterclockwise and then taken out in a direction perpendicular to the page. Since the cleaning device R2o is surrounded by the cleaning unit 320 on the lower side and both sides, the toner will not be scattered when the cleaning unit 320 is taken out.

In the present invention, a color image reading device using a color image sensor can also be used. Further, the developing device in the electrophotographic image forming apparatus can be configured by four developing devices each containing yellow (Y), magenta (M), cyan (C), and black (BK) toners. In this case, while the photoreceptor drum rotates four times, yellow (Y), magenta (M), cyan (C), and black (BK) toner images are formed on the photoreceptor, and these toner images are printed on the recording paper. A full color image is obtained by transferring.

The image data in the present invention is input from an image reading device, but it may also be output from a frame memory that stores image data created by CAD or the like or transferred image data.

〔Effect of the invention〕

The color image forming apparatus according to the present invention has three or four stages of developing devices stacked on one side of the photoreceptor drum, and develops in one direction using the developing device as a flat type as shown in the embodiment. When providing a toner storage section on the opposite side of the developing sleeve, the multi-stage developing devices can be arranged almost parallel to each other, allowing them to be placed in one developing unit, and the photoconductor drum Can be configured into a compact process cartridge with
It is advantageous to use a device with a so-called clamshell structure, which is divided into upper and lower halves in order to facilitate the removal of the process cartridge or the removal of jams. The present invention has such effects, and since the opening/closing shaft is provided on the developing unit side according to the present invention, the developing unit, which is a heavy part, is close to the opening/closing shaft, so it is relatively easy to open the upper housing, and the process cartridge Since the openings of the developing devices are all in an upward position when the developing device is taken out, there is no possibility that the developing device will spill or the developer will get mixed into other developing devices.

[Brief explanation of the drawing]

1(a) and 1(b) are schematic front views showing a first embodiment of a color image forming apparatus according to the present invention;
) shows the operating state, FIG. 1(b) shows the open state, FIG. 2 is a schematic front view showing the developing device of the color image forming apparatus according to the present invention, FIG. 3 is a schematic sectional view of the developing unit, and FIG. The figure is a front view showing a filter used for color separation, FIG. 5 is a block diagram showing a color image control circuit, and FIG.
) and (b) are schematic front views showing the second embodiment, FIG. 6(a) shows the operating state, FIG. 6(b) shows the open state, and FIG. 7 shows the third embodiment. A schematic front view showing the open state. 9... Filter 11... Photosensitive drum 1
2... Charger 13... Supply means (transfer material) 14... Transfer device 15... Separator 1
6... Conveying means (transfer material) 17... Fixing device 18.
... Paper discharge plate 19 ... Pre-cleaning static eliminator 20 ... Cleaning device 21 ... Platen glass 22 ... Image reading device 23 ... Laser exposure device 30 ... Development units 31Y, M, C ...Developer 40.240,340...Process cartridge 4
0 (240, 340) a, b, c - Retaining part 41... Label part 100... Main body 101
...Lower housing i02...Upper housing 103.
...Hinge 104...Opening/closing fitting 140a,
140b, 140cm - Support arm 141...Detection member 320...Cleaning unit Fig. 2

Claims (1)

[Claims] A developing unit including a plurality of developing devices each having a developer of a different color, an upper housing having a rotatable image carrier, and a cleaning means, and a lower housing arranged parallel to the rotation axis of the image carrier. , the plurality of developing devices are configured to be openable around an axis disposed near a side wall of the main body on the side of the developing unit with respect to the rotating shaft so that sides of the plurality of developing devices facing the image carrier face upward; the developing unit;
The image carrier and the cleaning means are integrally formed, or two of them are integrated and the other one is independently inserted into and removable into a cartridge; when forming an image having multiple colors, A color image forming apparatus characterized in that a color developed image in which a plurality of developed images are superimposed is formed on the image carrier by sequentially using the developing devices, and is transferred onto a transfer material at once.