JPH0561313A - Color image forming device - Google Patents

Abstract

PURPOSE:To miniaturize a color image forming device and to prevent an electrifier device, a transfer unit and a laser writing system from being stained with toner. CONSTITUTION:On the downward of a photosensitive belt 1 wound around turning rollers 2 and 3 and stretched therebetween, developing units 8, 9 and 10 storing their respective color developers are provided. On the upward of the belt 1, a developing unit 11 for black toner is provided. The electrifier 6 and the transfer device 12 are provided opposed to the curved surface of the photosensitive belt 1 wound around the turning roller 3. A cleaning device 13 is adjacent to the developing units 8 and 11 and opposed to the curved surface of the photosensitive belt on the side of the opposite turning roller 2. They are separated from one another. The electrifier device 6 and the transfer device 12 are shared or their positions are switched by integrally attaching them as an integral member. The stretched photosensitive belt 1, cleaning device 13 and developing units 8, 9, 10 and 11 are made in the forms of cartridges and attachably/detachably fitted in the color image forming device or the cartridge of a process unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color image forming apparatus in which a toner image is formed on a belt-shaped image forming body by an electrophotographic method and is transferred onto a transfer material to obtain an image.

[0002]

2. Description of the Related Art A conventional color image forming apparatus having an image carrier belt suspended substantially horizontally and a plurality of developing devices arranged in parallel on the lower surface of the belt is disclosed in, for example, Japanese Patent Laid-Open No. 61-151560. Described and known. According to the color image forming apparatus described in the above publication, the image carrier belt is arranged substantially horizontally and horizontally, and a plurality of developing devices are arranged in parallel on the lower surface of the belt with the development openings thereof facing upward. .. And
Around the image carrier belt stretched between two rotating rollers provided opposite to each other, an exposing section by a charger and a laser writing system, and yellow and magenta arranged at the above-described positions in the order of image formation. , A developing device for accommodating each of the cyan and black developers, and a transfer device provided at a predetermined interval so as to face the curved surface of the image carrier belt wound around one rotating roller. A fixing device is provided above the transfer device. A cleaning device is provided adjacent to the charging device, facing the curved surface of the image carrier belt wound around the other rotating roller and having a predetermined distance.

The color image forming apparatus having the above-described structure records color images one after another on recording paper that is intermittently conveyed.

[0004]

By the way, in a practical color printer or color copying machine, in addition to recording a color image on a recording paper, a document or an image is often recorded using only black toner requested by a user. Therefore, each color developing device containing black toner mounted in the color image forming apparatus is attached to one developing device cartridge to reach a predetermined number of developments. For example, when black toner is consumed, four colors are simultaneously replaced or discarded. It is supposed to be done. Therefore, other color toners, which are still much left in addition to the black toner, are replaced or discarded at the same time, which is very uneconomical, and the frequency of replacement increases, which is very troublesome. Further, if the cleaning device is close to the charging device and the transfer device as in the conventional case, the toner is scattered during the cleaning of the image carrier belt, and the surface of the lens and the mirror in the charging device, the transfer device and the laser writing system. Are contaminated and adversely affect the quality of the toner image formed on the image carrier belt or the recording paper. The present invention solves such a problem and makes it possible to economically replace each toner in a well-balanced manner for black-and-white and color image formation, and at the same time, a toner charging device, a transfer device, and a laser writing system can be used. An object of the present invention is to provide a color image forming apparatus capable of preventing contamination.

[0005]

[Means for Solving the Problems]
It is achieved by any of b, c and d.

(A) Color image formation in which a charging portion, an image exposing portion, a first developing means, a second developing means, a cleaning portion and a transfer portion are arranged around a stretched belt-shaped image forming body. In the apparatus, the first developing unit or the second developing unit is adjacent to the cleaning unit, one has a black toner, and the other has a plurality of specific color toners. Color image forming apparatus.

(B) In (a), each of the first and second
2. The color image forming apparatus according to claim 1, wherein the developing means is provided on two surfaces formed by the stretched belt-shaped image forming body.

(C) In the color image forming apparatus, the process section for forming an image in (a) is unitized and detachable from the image forming apparatus.

(D) A color image forming apparatus characterized in that the developing means for accommodating a plurality of color toners in (a) are detachable from the unit of the process section.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention is a side sectional view showing the construction of a color image forming apparatus of FIG. 1, a block diagram showing an image forming system of FIG. 2, and a construction of a charging device and a transfer device of FIG. Will be described with reference to FIG. 4, a block diagram showing the operation of the charging device and the transfer device shown in FIG. 4, and a side sectional view showing the configuration of the color image forming apparatus with another developing device arrangement shown in FIG. However, the present invention is not limited to this embodiment.

In FIG. 1, reference numeral 1 denotes a flexible photoconductor belt which is a belt-shaped image forming body. The photoconductor belt 1 is installed between rotary rollers 2 and 3 and is driven by the rotary roller 2. It is conveyed counterclockwise as indicated by the arrow.

Reference numeral 4 denotes a guide member fixed to the main body of the apparatus so as to be inscribed in the photoconductor belt 1. The photoconductor belt 1 is stretched by the action of the tension roller 5 so that its inner peripheral surface is The guide member 4 is rubbed. The guide member 4 is provided with a concave portion in an area unnecessary for image formation to reduce resistance due to rubbing. Of course, this recess may be omitted if the rubbing resistance is low. Further, a low friction member such as a Teflon coating is provided on either surface of the photoconductor belt 1 or the guide member 4 for the purpose of reducing the sliding resistance between the photoconductor belt 1 or the guide member 4, or is constituted by the above low friction member. Preferably.

Therefore, the photoconductor on the outer peripheral surface of the photoconductor belt 1 is always kept in a constant relation position with respect to the surface of the guide member 4 even during conveyance, so that a stable image forming surface can be formed. .

6 is a scorotron charger which is a charging means, 7 is a laser writing system unit which is an image exposing means,
Reference numerals 8 to 10 denote a plurality of developing units, which are second developing means for accommodating the developer of a specific color, and are stretched on the lower surface of the photosensitive belt 1 stretched in order from the left side with a predetermined gap. The developing device 11, which is the first developing means for accommodating the black toner, is disposed on the upper surface of the photosensitive belt 1 adjacent to the cleaning device 13.

As the laser writing system unit 7, an optical system in which a light emitting portion and a converging optical transmission body are integrated is used in addition to the optical system shown.

The developing units 8, 9, 10, and 11 contain, for example, yellow, magenta, cyan, and black developers, respectively, and the developing sleeves 8A and 9A keep a predetermined gap with the photosensitive belt 1. , 10A, 11A, and has a function of visualizing the latent image on the photoconductor belt 1 by a non-contact developing method. Unlike the contact development, the non-contact development has an advantage that the movement of the photosensitive belt 1 is not hindered.

A transfer device 12 is provided above the charging device 6 and slides up and down integrally with the charging device 6 to switch the position. 12A is a static eliminator, 13 is a cleaning device, and 13A is a blade of the cleaning device and 13 is a toner conveying roller.
B is kept at a position separated from the surface of the photosensitive belt 1 during image formation and is pressed against the surface of the photosensitive belt 1 as shown in the figure only during cleaning after image transfer.

The process of forming a color image by the color image forming apparatus 25 is performed as follows.

First, the formation of a multicolor image according to the present embodiment is shown in FIG.
Image forming system. That is, the data obtained by the color image data input unit (FIG. 2A) in which the image sensor scans the original image is processed by the image data processing unit (FIG. 2B) to create image data, This is once stored in the image memory (FIG. 2C). Then, the image memory is taken out at the time of recording and is recorded (see FIG. 2).
(D)), for example, is input to the color image forming apparatus 25 shown in the embodiment of FIG.

That is, the color signal output from the image reading apparatus separate from the printer is the laser writing system unit 7.
Is input to the laser writing system unit 7, the laser beam generated by the semiconductor laser (not shown) is rotationally scanned by the polygon mirror 7B rotated by the drive motor 7A, and passes through the fθ lens 7C and the mirror 7D. The optical path is bent by 7E, and a bright line is formed by being projected onto the peripheral surface of the photosensitive belt 1 to which electric charges have been previously given by the charger 6 as a charging means.

On the other hand, when the scanning is started, the beam is detected by the index sensor, the modulation of the beam by the first color signal is started, and the modulated beam scans the peripheral surface of the photosensitive belt 1. Therefore, a latent image corresponding to the first color is formed on the peripheral surface of the photosensitive belt 1 by the main scanning by the laser beam and the sub-scanning by the conveyance of the photosensitive belt 1. This latent image is subjected to reversal development in a non-contact state by the developing device 8 loaded with yellow (Y) toner (visual medium) in the developing means, and a toner image is formed on the belt surface. The obtained toner image passes under the cleaning device 13, which is a cleaning means separated from the peripheral surface of the photosensitive belt 1 while being held on the belt surface, and enters the next copy cycle.

That is, the photoconductor belt 1 has the charger 6
Then, the second color signal output from the signal processing unit is input to the writing system unit 7, and writing on the belt surface is performed in the same manner as in the case of the first color signal described above. The image is formed. The latent image is subjected to reversal development in a non-contact state by the developing device 9 loaded with magenta (M) toner as the second color.

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

Reference numeral 10 denotes a developing device having cyan (C) toner, which forms a cyan (C) toner image on the belt surface based on a control signal generated by a signal processing section.

Further, 11 is a developing device having a black toner, which is formed by superposing a black toner image on the belt surface by the same process. These developing devices 8, 9, 10 and
A direct current or an alternating current bias is applied to each sleeve of 11, and jumping development is performed by a one-component or two-component developer that is a developing device, and the development is performed in a non-contact manner on the photoreceptor belt 1 whose base is grounded. It is supposed to be done.

Thus, the color toner image formed on the peripheral surface of the photosensitive belt 1 is slid downward and switched to the position of the charging device 6, the transfer device 12 and the neutralizing plate.
At 12A, the image is transferred onto the transfer material sent from the paper feed cassette 14 through the paper feed guide 15.

That is, the transfer material contained in the paper feed cassette 14 is carried out by the rotation of the paper feed roller 16 and one of the uppermost layers is carried out, and the timing is adjusted with the image formation on the photoconductor belt 1 via the timing roller 17. And is supplied to the transfer device 12.

The transfer material subjected to image transfer and charge removal is more reliable than the photosensitive belt 1 which suddenly changes its direction along the rotating roller 2 without being affected by the charge removal effect on the image quality such as toner scattering. And then move it upwards to the fixing roller.
The image is fused by 18 and then discharged onto a tray 20 via a discharge roller 19.

On the other hand, in the cleaning device 13, the photosensitive belt 1 which has been transferred to the transfer material is further conveyed and the blade 13A facing the rotating roller 3 and the rotating toner conveying roller 13B are brought into pressure contact with each other. After the residual toner is removed and after the completion of the removal, the blade 13A is separated again, and a little later, the toner carrying roller 13B is separated, and a new image forming process is started.

The charging device 6 and the transfer device 12 are shown in FIGS. 3 and 4.
An example of switching between and will be described below.

The integral member 60 for integrally holding the transfer device 12 having the charge eliminating plate 12A and the charger 6 is constantly provided, for example, by a spring 32 having one end fixed to a part of the frame of the color image forming apparatus 25 as shown in FIG. It is pulled downward and is positioned and locked by a stopper 6C.

As shown in the block diagram of FIG. 4, when the image forming sequence is started by the start of copying from an operation unit (not shown), the solenoid 30 located above the transfer unit 12 shown in FIG. Signal sent to solenoid 30
Is turned ON, the integral member 60 holding the transfer device 12 and the charger 6 is pulled upward through the arm 61 engaging with the solenoid plunger 31 against the tension of the spring 32. The integral member 60 is a slide portion 62 and a fixed guide.
The charger 6 is moved along an engaging groove (not shown) appropriately engaged with the 63, and the charger 6 is pulled up to a position facing the curved portion at the right end of the belt photosensitive member 1 with a predetermined gap.

By the above-mentioned processes, the toner of a predetermined color is formed on the belt photosensitive member 1, and the transfer material start signal (held by the second paper feed roller 17) is set in order to set the paper feed registration timing at the timing of starting the transfer. When the second paper feed roller drive signal) is issued, the drive signal from the control section is received and the solenoid 30 is de-energized. Then, the integral member 60 is slid downward by the tension of the spring 32 via the slide portion 62 and the fixed guide 63 and returns to the position of the stopper 6C, and the transfer device 12 and the neutralization plate 12A transfer process (transfer,
(Separation) is switched to a state in which it operates.

Even if the positions of the transfer device 12 and the charging device 6 are attached to the integral member 60 contrary to the above example, it goes without saying that the mode of switching is included in the present invention.

Although not shown, the charging device 6 and the transfer device 12
It is also possible to switch the output from the same power source so as to output 4 kv and 0.25 mA when the scorotron charging is charged to the photosensitive belt 1 and output 5 kv and 2-3 mA during the transfer. The space is reduced and the color image forming apparatus 25 can be made compact.

The charging device 6 is composed of a transfer device 12 and a discharging plate 12A.
However, even if they are separately arranged, they are sufficiently isolated from the cleaning device 13.

The cleaning device 13 is arranged at a predetermined interval so as to face the curved surface at the left end of the photosensitive belt 1 wound around the rotating roller 2, and the waste toner box 13C is cleaned. It is provided so as to be connected below the device 13.

As described above, the developing device 11 for accommodating the black toner is separated from the other developing devices 8, 9, 10 and is provided on the upper surface of the photosensitive belt 1 adjacent to the cleaning device 13. The amount of toner contained is set to, for example, 1.5 to 2.0 times the amount of toner contained in each of the other developing units 8, 9, and 10 so as to correspond to the image formation using only black toner. Therefore, it is possible to sufficiently meet the user's request for the image formation of only black color, and the consumption amount of the toner contained in each of the other developing devices 8, 9 and 10 does not become unbalanced. ing. The developing device 11 is made into a cartridge and is detachably attached to the color image forming apparatus 25. Further, each of the developing devices 8, 9 and 10 for accommodating the developer of the specific color is, for example, yellow from the left side on the lower surface of the photosensitive belt 1 stretched adjacent to the cleaning device 13.
It is arranged in the order of magenta and cyan.

The cleaning device 13 and the waste toner box 13C are formed into a cartridge together with the developing devices 8, 9, 10, 11 and the stretched photoconductor belt 1 as shown by a chain line to form a color image forming device 25. It is designed to be detachably attached.

Further, at least the process of the photosensitive belt 1 and the cleaning device 13 and / or the waste toner box 13C is made into a cartridge, and the developing devices 8, 9 and 10 and the developing device 11 for accommodating the black toner are made into a cartridge. Each of them may be detachably mounted in the color image forming apparatus 25 or in the process cartridge.

Therefore, the charging device 6, the transfer device 12, and the static eliminator 12A
The cleaning device 13 and the cleaning device 13 are provided in the color image forming device 25 even if toner is scattered from the cleaning device due to the cartridges which are arranged separately on both ends in the longitudinal direction of the photoconductor belt 1 and whose outer periphery is hermetically formed. Since it hardly diffuses, the charging device 6, the transfer device 12, and the optical systems 7A, 7B, 7C, 7D, 7 of the laser writing system unit
A stable color image is formed even when the color image forming apparatus 25 is operated for a long time without being contaminated by toner such as E.

Further, the charging device 6 and the transfer device 12 are commonly used, or both of them are integrally connected so that they can be slid up and down and switched to a predetermined position of the photosensitive belt 1 as required for image formation. The color image forming apparatus 25 can be downsized. In the above-described embodiment, when the developing devices 8, 9 and 10 are located below and the developing device 11 is located above the stretched photoreceptor belt 1 (especially, the developing system using one-component magnetic toner is used as the black developer). Thus, the color image forming apparatus 25 has been described, in which toner can be prevented from leaking from the developing device disposed on the upper side), but as shown in FIG. 5, the developing devices 8, 9 and 10 are disposed above. The case will be described below. That is, above the photosensitive belt 1 which is stretched around the rotating rollers 2 and 3 and rotates clockwise as indicated by the arrow, adjacent to the cleaning device, for example, yellow, magenta, and cyan developers are accommodated in order from the left. Each of the developing devices 8, 9 and 10 is arranged at a predetermined distance from the photoconductor belt 1, and its lower cleaning device 13 and a waste toner box 13C.
Each of the developing devices 11 for accommodating the black toner is provided adjacent to the above and has the same function as that of the above-described embodiment. The cleaning device 13 is arranged opposite to the curved surface of the photosensitive belt 1 wound around the rotating roller 2 as in the above-described embodiment, and the waste toner box 13C is connected therebelow.

On the other hand, the charger 6, the transfer electrode 12 and the static eliminator 12A
Is configured in the same manner as described in the above-mentioned embodiment, and is provided at a predetermined interval so as to face the curved surface of the photosensitive belt 1 on the side opposite to the cleaning device 13. Then, the photosensitive belt 1, the cleaning device 13, and the developing devices 8, 9, 1
0 and 11 are formed into a cartridge as shown by a chain line and are detachably attached to the color image forming apparatus 25.

Incidentally, in this cartridge formation, the cartridges of the developing devices 8, 9, 10, 11 and the photosensitive belt 1, the cleaning device 13, and the cartridge of the waste toner box 13C are separately configured in the same manner as described above. May be.

As shown in FIG. 5, the laser writing system unit 7 is disposed below the developing device 11 so that the surface of the photosensitive belt 1 is exposed between the right side of the developing device 11 and the charging device 6. Is becoming On the other hand, although not shown in the drawings, the paper feeding / conveying system including the paper feeding cassette 14, the paper feeding roller 16, and the timing roller 17 having the same function as shown in the above-described embodiment is the developing devices 8, 9, 10
The transfer material is arranged above and is fed downward with respect to the photosensitive belt 1 as indicated by an arrow. Therefore, the fixing roller 18 and the paper discharge roller 19 are located below the color image forming apparatus 25, contrary to the above-described embodiment.

Color image forming apparatus configured as described above
Also in the same manner as in the above-described embodiment, the cleaning device 25 is provided with the cleaning device 13 adjacent to the developing devices 8 and 11, and the cleaning device 13
Since the charging device 6, the transfer device 12, and the charge removing plate 12A are sufficiently isolated from each other, it is possible to prevent the charging device 6 and the transfer device 12 from being contaminated by toner.

Further, at least the photosensitive belt 1, the cleaning device 13 and the waste toner box 13C can be made into a cartridge in a sealed state as shown by a chain line as in the previous embodiment, so that the toner in the color image forming apparatus 25 can be prevented. Scattering is prevented and the optical systems 7A, 7B, 7C of the laser writing system unit 7,
7D and 7E are kept clean.

Since the developing device 11 for accommodating the black toner having a larger capacity than the other developing devices 8, 9 and 10 is independently arranged, a toner image of only black color which is frequently used is generated. It can sufficiently respond to user requests. Further, as shown by the dotted line in the figure, the recycled pulp 13D is connected to the waste toner box 13C and the developing device 11 (for black toner), and the black toner which is consumed more than the others is consumed before each color toner. In this case, a control unit (not shown) of the image forming apparatus 25 outputs a signal for recycle replenishment so that the recycle apparatus (not shown) including the recycle pipe 13D can be operated.

[0049]

The cleaning device of the present invention, the waste toner box, the charging device, and the transfer device are separated from each other, and the toner belt is scattered and diffused in the image forming apparatus by using the photosensitive belt, the cleaning device, and the developing device as a cartridge. Since it was remarkably prevented, it was possible to prevent toner contamination of the charging device, the transfer device, and each optical system in the laser writing system.

Further, since the charging device and the transfer device are used in common or connected to each other so that they can be switched to a predetermined position on the photosensitive belt, the image forming apparatus can be downsized.

Further, since the capacity of the developing device for accommodating the black toner is increased and the developing device is arranged separately from the other developing devices, it is possible to economically cope with the frequent black and white image formation. became.

[Brief description of drawings]

FIG. 1 is a side sectional view showing the configuration of a color image forming apparatus according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the image forming system of the above.

FIG. 3 is a side view showing a configuration of a charging device and a transfer device according to an embodiment of the present invention.

FIG. 4 is a block diagram showing the operation of a charging device and a transfer device.

FIG. 5 is a side sectional view showing the configuration of a color image forming apparatus in which a developing device is arranged at another position according to an embodiment of the present invention.

[Explanation of symbols]

 1 photoconductor belt (image forming belt) 2 rotating roller 3 rotating roller 6 charger 7 laser writing system unit 8 developing device (yellow) 8'developing device (black) 9 developing device (magenta) 9'developing device ( Black) 10 Developing device (cyan) 10 'Developing device (black) 11 Developing device (black) 12 Transfer device 12A Discharging plate 13 Cleaning device 13C Waste toner box 18 Fixing roller 25 Color image forming device 30 Solenoid 60 Integrated member

Claims (4)

[Claims] 1. A color image forming apparatus in which a charging unit, an image exposing unit, a first developing unit, a second developing unit, a cleaning unit and a transfer unit are arranged around a stretched belt-shaped image forming body. In the above, the first developing means or the second developing means is adjacent to the cleaning section, one has black toner, and the other has color toners of a plurality of specific colors. Color image forming apparatus. 2. The belt-shaped image forming body formed by stretching the first and second developing means according to claim 1,
A color image forming apparatus, which is provided on one surface. 3. The color image forming apparatus according to claim 1, wherein the process unit for forming an image is unitized and is attachable to and detachable from the image forming apparatus. 4. The color image forming apparatus according to claim 1, wherein each of the developing means that stores a plurality of color toners is attachable to and detachable from a unit of the process section.