JP2888008B2 - Color electrophotographic method and apparatus - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color electrophotographic method and apparatus applicable to a printer, a facsimile or the like.

[0002]

2. Description of the Related Art Conventionally, a color electrophotographic apparatus is, for example, an apparatus in which four image forming units each containing a color developer and a photoreceptor are sequentially arranged on a paper transport path so that full-color color development can be performed. Etc. are being developed. An example of such an apparatus is shown in FIG.

FIG. 1 illustrates only a printer unit which is an image forming unit of a copying machine disclosed in Japanese Patent Application Laid-Open No. 2-158080.
The digital signal sent from the image reading unit is input to the printer unit, and a laser light exposure device for each color signal,
Sent to black 1Bk, cyan 1C, magenta 1M, yellow 2Y. The printer unit has four recording devices 2Bk, 2C,
2M and 2Y are juxtaposed. Since the recording devices 2 are made of the same components, the recording device for C will be described, and the other colors will be omitted. The same reference numerals are assigned to the same parts for each color, and a suffix indicating each color is added to the reference numerals to distinguish the configuration of each color. The recording device 2C has a photosensitive drum 3 in addition to the laser exposure device 1C.
C. The photoconductor 3C is provided with a charger 4C, a laser exposure device 1C, a developing device 5C, a transfer charger 6C, and the like, similarly to a known copying device. The photoconductor 3C uniformly charged by the charger 4C forms a latent image of a cyan light image by exposure by the exposure device 1C, and develops by a developing device 5C to form a visible image. The transfer paper (not shown) is conveyed by the transfer belt 7 and sequentially sent to the photoconductors 3Bk, 3C, 3M, and 3Y on which the visualized images are formed, and the visualized image is transferred by the operation of the transfer device 6. Thus, a full-color image can be obtained on the transfer paper.

Further, in a generally used color image electrophotographic apparatus, a method of forming a color image by superimposing toner images of yellow, magenta, cyan and black colors is adopted. As a general method for superimposing the toner images on a transfer material, there is an example of a color image forming apparatus disclosed in Japanese Patent Application Laid-Open No. 1-252982.

FIG. 2 shows an outline of the overall configuration of the conventional example, and the configuration and operation will be briefly described below. In FIG. 2, reference numeral 8 denotes a photoreceptor, and a charger 9 faces the photoreceptor.
, A developing unit 10, a transfer drum 11, and a cleaner 12. The developing unit 10 includes a Y developing unit 13 for forming a yellow toner image, an M developing unit 14 for magenta, a C developing unit 15 for cyan, and a B developing unit for black.
The image forming apparatus includes a k developing device 16, and the whole is rotated so that each developing device can sequentially face the photoconductor 8 to be in a developable state. During operation, the transfer drum 11 and the photoconductor rotate at a constant speed in the direction of the arrow while facing each other.

First, when the operation starts, the photoconductor 8 rotates in the direction of the arrow, and the surface thereof is uniformly charged by the charger 9. Thereafter, the surface of the photoconductor is irradiated with a laser beam modulated with a signal for forming a first yellow image, thereby forming a latent image. Further, this latent image is first developed in the yellow developing unit 13 facing the photoreceptor to form a yellow toner image. By the time the formed yellow toner image comes to a position facing the transfer drum 11, one sheet sent from the paper feeding unit 18 is already gripped on the outer periphery of the transfer drum 11 by the claw 19. The toner image is formed at a timing such that the yellow toner image on the photoconductor faces the predetermined position of the paper so as to face each other.

After the yellow toner image on the photoreceptor is transferred to the sheet by the action of the transfer charger 20, the surface of the photoreceptor is cleaned by the cleaner 12 to prepare for the next color image formation. Subsequently, magenta, cyan, and black toner images are formed in the same manner. At that time, the developing unit 10 sets each developing device used in accordance with the color to be in a state where it can be developed by facing the photosensitive member. The diameter of the transfer drum is sufficiently large so that the switching of the developing device can be performed in time and the toner image of the previous color and the toner image of the next color overlap.

In the irradiation of the laser beam 17 for forming an image of each color, the toner image of each color on the photoreceptor and the toner image already transferred to the sheet on the transfer drum are opposed to each other while rotating in rotation. The timing is as follows. In this manner, the four color toner images are transferred onto the paper on the transfer drum 11 in a superimposed manner, and a color image is formed on the paper. After the toner images of all colors have been transferred, the sheet is peeled off from the transfer drum
, The upper toner image is fixed by the fixing device 23 and is discharged out of the apparatus.

[0009]

However, in the configuration shown in FIG. 1, the configuration of the developing device is large, the recording apparatus for each color becomes large and complicated, and four laser exposure devices are required, which increases the cost. Had a point.

Further, in the apparatus shown in FIG. 2, a transfer drum is used to align and overlap toner images of different colors. However, in the above configuration, even when a single-color image is formed using only one developing device, it is necessary to wind the paper once on the transfer drum and then transfer the toner image on the photoconductor to this paper. Therefore, the copy speed in the single-color mode is lower than that in a normal single-color copying machine.

In addition, in order to operate the transfer drum which is originally unnecessary at the time of a single color copy, even if a large amount of a single color copy is performed by this apparatus, maintenance and replacement of parts specific to the transfer drum similar to the color copy are performed. Is needed.

1 and 2, when a color image is continuously printed in a high-temperature environment, the charged potential of the photosensitive member gradually decreases due to electrostatic fatigue and a rise in temperature because the photosensitive member is continuously used. There is a problem that the resulting image gradually changes.

[0013]

Color electrophotographic apparatus SUMMARY OF THE INVENTION The present invention includes a plurality of image forming units having at least the photosensitive member and the developing device can be moved, the transfer for transferring a toner image
And body, becomes more and exposure means, said A color electrophotographic apparatus each developing device to have a plurality of color toners of the image forming unit, and said image forming unit is opposite to the transfer member
A first image forming position and a second image forming position different therefrom
Is a color electrophotographic apparatus.

[0014] Color electrophotographic apparatus of the present invention includes a plurality of image forming units having at least the photosensitive member and the developing device can be moved, a transfer member for transferring the toner image becomes more and exposure means, the A color electrophotographic apparatus in which each developing unit of each image forming unit has a plurality of color toners, and
The color electrophotographic apparatus has a color mode and a monochrome mode.
In the color mode, each of the image forming units is
To the first image forming position, and
An electrostatic latent image is formed on the photoreceptor of the image forming unit and
After image formation, the toner images of each color are sequentially transferred onto the transfer body.
A color image is formed, while a second image is formed in the monochrome mode.
Single color developed at one of the imaging units at the location
The toner image on the receiving paper without using the transfer body.
Is a color electrophotographic apparatus for transferring an image.

[0015] Further color electrophotographic method of the present invention is, move
A plurality of movable units having at least a photoconductor and a developing unit.
Image forming unit, transfer body for transferring toner image, and exposure
Means, and each developing unit of each image forming unit is
A color electrophotographic apparatus having several colors of toner, or
The color electrophotographic apparatus has a first
And a second image forming position remote from the transfer body
Wherein the exposure means has a first image shape in a color mode.
A first state acting on the image forming unit at the formed position;
The image forming unit at the second image forming position in the monochrome mode
Is a color electrophotographic apparatus that can be switched between a second state and a second state .

Still further, in the color electrophotographic method of the present invention, a single color image of a plurality of colors is synthesized to form a color image.
Electrophotographic method, wherein each said single color of color image formation
The usage time of the photoconductor in the image forming process is defined as T, and the next photoconductor is used.
T is the time for electrostatically resting the photoconductor until use of
At this time, a process in which T <t is repeated to form a color image
It is a color electrophotographic how to.

Further, the color electrophotographic apparatus according to the present invention is a color electrophotographic apparatus which forms the same image continuously plural times.
In the method, each single-color image of multiple colors is combined
The photosensitive member during continuous use of color image formation.
A color electrophotographic method , comprising a step of electrically resting .

[0018] Finally, the present invention will become more and a plurality of image forming units having a developing unit and the photosensitive member even without low, and the rolling Utsushitai for transferring a toner image, and a single exposure device, wherein each image each developing device forming unit has a plurality of color toners, wherein
A color electrophotographic apparatus and the exposure position is fixed with the transfer position of the transfer member the exposure apparatus, at the time of color image formation
By rotating the image forming unit group is whole, each image forming unit is moved to the same image forming position in order to form an electrostatic latent image on the photosensitive member of the image forming unit using the exposing device
After development with a color toner, a color electrophotographic apparatus for forming a color image by transferring a toner image on the transfer member.

[0019]

As in the present invention, by moving the miniaturized image forming unit, it becomes possible to unify the exposure apparatus, so that the overall configuration of the apparatus is simplified and the size can be reduced. .

Further, a first image forming position of which is opposed to the image forming unit inversion Utsushitai, by providing a separate image forming position to this, in the monochrome print mode needs to hold the sheet rolling in Utsushitai And an image can be formed by the same operation as that of a general monochrome image forming apparatus. In addition, significantly reduced the need for maintenance associated with, such as the rolling Utsushitai of deterioration.

Further, in the present invention, since a step of stopping the photosensitive member during the image forming step is provided, the photosensitive member does not become fatigued or its temperature does not rise even during continuous use, and the electrostatic characteristics of the photosensitive member are stabilized. Thus, a constant image can always be obtained.

[0022] According to yet again present invention, by rotating moving the image forming unit which is miniaturized, since the basic blocks necessary for color image formation becomes two positions of the image forming unit group and the rolling Utsushitai In addition, the configuration of the entire device can be simplified and the device can be downsized.

[0023]

DESCRIPTION OF THE PREFERRED EMBODIMENTS As a developer used in the present invention, a two-component developer composed of a mixture of a toner and a magnetic carrier can be used.

The toner used in the present invention is obtained by dispersing a color pigment such as carbon black or phthalocyanine in a binder resin such as a styrene resin or an acrylic resin, pulverizing the pigment, and classifying the resultant. The toner may be a powder obtained by spray drying or a powder obtained chemically by a pearl polymerization method or the like. Further, the toner particles may be mixed with the carrier as it is, or may have silica fine particles or fluororesin fine powder adhered to the toner surface depending on the use conditions. The average particle size of the toner used is 15
μm or less is desirable, but when it is 12 μm or less, a sharper image was obtained. If the thickness is less than 5 μm, the transfer performance is deteriorated and toner cleaning failure occurs.

The carrier used in the present invention may be a magnetic material such as iron powder or ferrite powder, or a material obtained by coating the surface thereof with a resin, or a fine powder such as ferrite powder or magnetite at a ratio of about 30 to 80% by styrene resin. A magnetic powder or the like, which is dispersed and mixed in an epoxy resin, a styrene acrylic resin, or the like, and crushed and classified, is used. The average particle size of the carrier is 30
The thickness is preferably 0 μm or less. In particular, when the thickness is 150 μm or less, the toner can be uniformly charged.

The one-component toner used in the present invention is obtained by dispersing magnetite or ferrite powder together with a charge controlling agent in a binder resin such as a styrene resin or an acrylic resin, pulverizing the powder, and then classifying the powder. Depending on the conditions of use, the toner may have silica fine particles or fluororesin fine powder adhered to the surface of the toner. Average particle size of toner used is 15μ
m or less is desirable, but when it is 12 μm or less, a sharper image was obtained. As the photoreceptor used in the present invention, an organic photoreceptor using zinc oxide, selenium, cadmium sulfide, phthalocyanine or an azo pigment can be used. These photoconductors, like general semiconductors, tend to have lower resistance at high temperatures and lower charge retention performance.

In the present invention, as the toner image transfer body for transferring the toner image from the image forming unit, a configuration as shown in FIG. 1 in which paper is electrostatically brought into close contact with a dielectric belt and conveyed can be used. Further, as in the apparatus shown in FIG. 2, a transfer drum for winding and transferring paper around a dielectric drum or the like may be used. Further, an intermediate transfer method may be adopted in which after all the toner images are once transferred onto the dielectric belt, this color image is collectively transferred onto paper again. (Embodiment 1) FIG. 3 illustrates an image forming section of a color electrophotographic apparatus according to the present invention. The color digital signal is input to the printer unit and sent to the laser light exposure device 24.
The printer unit includes four image forming units 25Bk and 25Bk.
C, 25M, and 25Y are arranged side by side. Each of the image forming units 25 is made of the same constituent members except for the developer contained therein. Therefore, for simplicity of description, the image forming unit for black will be described, and other colors will be omitted. For each color, the same portions are denoted by the same reference numerals, and a suffix indicating each color is added to the reference numerals to distinguish the configuration of each color. FIG. 4 shows the image forming unit 2 for black.
5Bk is shown. The image forming unit 25Bk includes an electrophotographic photosensitive drum 27 including a magnet 26 fixed to a shaft,
It comprises a charger 28, a toner hopper 29, a toner collecting electrode roller 30, a magnetic one-component toner 31, and a toner regulating plate 32. The position of the magnet 26 is fixed inside the photoconductor 27, and the position of the magnetic pole faces the inner surface of the toner hopper 29, so that the fixed magnet does not follow the rotation of the photoconductor drum. The photoreceptor 27 is charged to -400 V by the charger 28, and then exposed to laser light 33 to form an electrostatic latent image. In the toner hopper 29, the magnetic one-component toner 31 is magnetically attracted to the electrostatic latent image formed in this manner on the surface of the photoconductor 27, and the toner is attached to the surface of the photoconductor 27. The amount of toner adhering to the surface of the photoreceptor 27 is regulated to a thickness of about 50 μm by a toner regulating plate 32, and thereafter, the toner is passed in front of the toner collection electrode roller 30 which is opposed to the photoreceptor 27 with a gap of 300 μm. . An AC high-voltage power supply 34 is
AC voltage (frequency: 1 kHz, AC: 1 kVrm)
s, DC bias: -350 V) was applied to visualize the image on the photoreceptor.

FIG. 5 shows the configuration of a color yellow, magenta, and cyan image forming unit. Each component of the unit is the same as that of the black image forming unit shown in FIG. 4, but the configuration of the developer 35 put in the toner hopper 29 is different. The developer 35 includes the magnetic carrier 36 and the color toner 3
7 is a two-component developer. The color toner 37 is
It is configured to be charged in contact with the carrier 36 and electrostatically adhere to the photoconductor, and the other image forming processes are the same as in the case of black.

Referring again to FIG. 3, the process of forming a full-color image will be described. Transfer paper (not shown) is fed from a paper feed unit 37 and wound around a transfer paper holder 38 made of a 100 μm-thick polyester film. First, the black image forming unit 25Bk is sent to the image forming position, and the black component signal light is exposed by the laser 24. The formed latent image is visualized in the image forming unit 25Bk, and the toner image is transferred to paper by the operation of the transfer device 39. This time, the cyan image forming unit 25C is moved to the position where the previous black image forming unit is placed, and is replaced with black to form an image. The same image forming process was then repeated using the magenta unit 25M and finally the yellow unit 25Y to obtain a beautiful full-color image on transfer paper. Thereafter, the paper was separated from the transfer paper holding member by a pair of separation chargers 40, and finally heat-fixed by a fixing device 41.
As a result, a beautiful full-color image was obtained. (Embodiment 2) FIGS. 6 and 7 illustrate only a printer section for forming an image of a color electrophotographic apparatus according to the present invention.
6 shows the state of the apparatus in the color mode, and FIG. 7 shows the state in the monochrome mode.

First, four image forming units 42Bk, 42C, 42M, and 42Y are arranged in the printer unit. Each of the image forming units 42 is made of the same constituent members except for the developer contained therein. Therefore, for simplification of description, the image forming unit for black will be described, and other colors will be omitted. For each color, the same portions are denoted by the same reference numerals, and a suffix indicating each color is added to the reference numerals to distinguish the configuration of each color.

FIG. 8 shows the black image forming unit 42Bk in detail. In FIG. 8, reference numeral 43 denotes an organic photosensitive drum in which phthalocyanine is dispersed in a polyester binder resin;
4 is a magnet consisting of two magnetic poles fixed coaxially with the photoconductor 43, 45 is a corona charger for negatively charging the photoconductor, 46 is a grid electrode for controlling the charging potential of the photoconductor,
47 is a laser beam scanning light, and 48 is a toner hopper. In the toner hopper 48, a two-component developer 51 obtained by mixing a toner 50 with an iron powder carrier 49 having a particle diameter of 100 μm and having a surface coated with a silicone resin was placed, and was adhered to the surface of the photoreceptor 44 by magnetic force. The toner used was composed of styrene acrylic resin, 5% of carbon black, and 2% of oxycarboxylic acid metal complex, and 0.1% of colloidal silica was externally added (in each case, weight%).

Reference numeral 52 denotes a toner amount regulating plate made of nickel, which is a magnetic substance; 53, a toner collecting electrode roller made of aluminum; 54, an AC high-voltage power supply for applying a voltage to the toner collecting electrode roller; A scraper made of polyester film that scrapes toner.
The magnetic flux density on the surface of the photoconductor 43 is 800 Gs. The photoreceptor 43 had a diameter of 30 mm and was rotated at a peripheral speed of 30 mm / s.

The operation of the electrophotographic apparatus configured as described above will be described below with reference to FIG. Photoconductor 4
3 is a corona charger 45 (applied voltage -4 kV, grid 46
At a voltage of -500 V). The photosensitive member 43 was irradiated with laser beam scanning light 47 to form an electrostatic latent image. At this time, the exposure potential of the photoconductor was -100V. The photoconductor 4 on which the electrostatic latent image is formed in this manner
3 passes through the developer 51, the two-component developer 51 is attracted by the magnet and does not move, but only the toner 50 is
After passing through the toner amount regulating plate 52, a uniform toner layer of about 30 μm was obtained on the photoreceptor 43. At this time, a voltage of -500 V was applied to the toner amount regulating plate 52. Here, the toner was charged to approximately −3 μC / g. Next, the photoconductor 43 to which the toner layer was attached was passed in front of the toner collecting electrode roller 53. The toner recovery electrode roller 53 is supplied with a high-voltage power supply 54 with the waveform shown in FIG.
400V0-p (800V peak-to-peak) AC voltage superimposed with -300V DC voltage (frequency 300H
z) was applied. The toner layer on the photoconductor 43 is
The toner in the non-image area gradually moved to the toner collection electrode roller 53 side, and a negative-positive toner image was left only on the image area on the photoconductor 43. The toner adhered on the toner collecting electrode roller 53 was scraped off by the scraper 55, returned to the toner hopper 48 again, and used for the next image formation. Thus, a black toner image is obtained on the photoconductor 43. The other developing units 42C, 42M, and 42Y other than black have the same configuration, and perform the same image forming process.

Referring again to FIG. 6, the configuration of the printer unit in the color mode will be described. Image forming units 42Bk, 42C, 42M, 42 arranged side by side
Y is movable in the horizontal direction as a whole, and each image forming unit is sequentially moved to the first image forming position 5 facing the transfer paper holder 55.
6 can be located. Reference numeral 57 denotes a laser exposure device that generates a laser beam scanning light 58 modulated by a signal input to the printer unit. In the state shown in FIG. 6, this light is reflected by a mirror 59 and is at the first image forming position 56. The photosensitive member of the image forming unit is irradiated to form a latent image. The mirrors 60 and 61 are for the monochromatic mode, and do not function in the state shown in FIG. Reference numerals 62 and 63 denote static elimination lamps fixed to the main body. One is at a position for irradiating the surface of the image forming unit at the first image forming position after the transfer of the photoconductor, and the other is the right-hand image forming unit. Is in a position to act on.

Reference numeral 55 denotes a transfer paper holder, which is basically formed by forming a 100 μm-thick polyester film into a cylindrical shape, and adsorbing the paper onto the surface thereof and rotating the toner image of four colors in the same position on the paper during four rotations. A transfer charger 64 at a position corresponding to an internal first image forming position, and further, static eliminators 65 and 66 for neutralizing the transferred toner image, paper, polyester film, and the like. Further, it has a cleaner 67, an adsorption charger 68 for adsorbing paper on the polyester film, and the like. Reference numeral 69 denotes a separation charger for separating the paper from the polyester film after the completion of all the transfer. This separation charger 69 has an image forming unit,
When moving to the left from the state of FIG. 6, it is retracted to the position 69 '. Reference numeral 70 denotes a paper feed unit, from which paper is fed and passes through a paper feed path 71. In the state of FIG.
By the action of 2, the sheet is guided to the first sheet feeding path 73 and supplied to the transfer sheet holder. The second paper feed path 74 and the transfer charger 75
Does not work in color mode. A fixing device 76 fixes the toner image on the sheet after the transfer.

The main configuration of the electrophotographic apparatus of the present invention and the state in the color mode have been described above. Next, the image forming operation at this time will be described. A sheet (not shown) is fed from the sheet feeding unit 70 and is wound around the transfer sheet holder 55 through the above-described sheet feeding path by the operation of the attraction charger 68. First of all, Figure 6
Each image forming unit is moved to the left side in the drawing with respect to the position, and the yellow image forming unit 42Y is at the first image forming position 56 facing the transfer sheet holder, and the yellow component signal light is Exposure. The formed latent image is visualized in the image forming unit 42Y as described above, and the toner image is transferred to paper by the operation of the transfer charger 64.
Next, each image forming unit is moved rightward, and the magenta image forming unit 42M is moved to the first image forming position 56 where the yellow image forming unit is located, and is replaced with yellow to form the same image. Do the process. At this time, the transfer paper holder 55 around which the paper is wound makes one rotation, and the magenta toner image is transferred to the same position as the yellow image on the paper.
Similarly, this process was repeated using the cyan unit 42C and finally the black unit 42Y to obtain a beautiful full-color image on transfer paper. Thereafter, the paper was separated from the transfer paper holder by a separation charger 69, and finally heat-fixed by a fixing device 49. As a result, a beautiful full-color image was obtained. The above is the description of the operation in the color mode of the electrophotographic apparatus of the present embodiment.

Next, the operation in the monochrome mode will be described with reference to FIG. In the monochromatic mode, the configuration of the entire apparatus is the same as that in the color mode, and only the states of some components are different. Therefore, the operation of that part will be described. The image forming unit is at the position shown in FIG. 7 in the monochromatic mode, the black image forming unit 42Bk is at the second image forming position 77, and a transfer charger 75 in the monochromatic mode is provided correspondingly. . The image forming unit 42Bk has a discharging lamp 6
3 works. The mirror 60 has moved to the position 60 'as shown in the monochromatic mode, and the laser beam scanning light 58 emitted from the laser exposure device 57 is reflected by the mirror 60' and the mirror 61 to form the second image. Irradiation is performed on the photoconductor of the black image forming unit 42Bk at the forming position 77. The switching claw 72 at the rear of the paper feed path 71 is at a position as shown in FIG.
After that, the image is supplied to the second image forming position 77. Here, the separation charger 69 has moved to a position 69 'shown in FIG.

Each part of the apparatus is in the above state,
The paper sent from the paper supply unit 70 is transferred with a black toner image at the second image forming position 77 via the paper supply paths 71 and 74, and then passes over the transfer paper holder 55 in this case. It is sent to the fixing device 76. At this time, the transfer paper holder 55 is only rotating, and each charger and others do not operate. Therefore, deterioration of each part of the transfer paper holder, dirt, and the like due to these operations are scarce in this mode. (Embodiment 3) The color electrophotographic method of the present invention will be described using the color electrophotographic apparatus shown in FIGS. 6 and 8 again.
The operation will be described with reference to FIG. The diameter of the photosensitive member 43 of each image forming unit was 30 mm, and the photosensitive member 43 was rotated at a peripheral speed of 180 mm / s. Using this image forming unit, an image was formed using the same steps as in Example 2.

At this time, the image forming units 42Bk, 42Y, 4Y, and 4Y at an ambient temperature of 40 ° C. (the temperature in the apparatus is 45 ° C.)
FIG. 10 shows changes in the charging potential of the photoconductors used in 2M and 42C in FIG.
This is indicated by a three-dot chain line. The solid line in FIG. 10 shows the change in the charging potential when the same photosensitive member is continuously used. As shown in FIG. 10, when the photoconductor is continuously used in a high temperature environment, the surface potential thereof gradually decreases, and the obtained image changes. However, according to the configuration shown in this embodiment, the photoconductor of each image forming unit is changed. When the color image formation is not used, the photosensitive member is placed in a dark place without being subjected to electrostatic stress such as corona charging or light elimination, and the rotation of the photosensitive member is also stopped, so that the temperature rise can be suppressed. In this case, assuming that the photoconductor usage time in each single-color image forming step of color image formation is T, the time t for electrostatically resting the photoconductor until the next photoconductor of the same image forming unit is used is T. , During which time the photoreceptor can fully recover from electrostatic fatigue and can be imaged with the same potential characteristics at the next use. As a result, a stable and beautiful color image can always be obtained. The relationship between the photoconductor use time T and the photoconductor rest time t is T
<T was effective. (Embodiment 4) Next, the effect of the color electrophotographic method of the present invention will be described again with reference to FIG. Next, an operation for continuously producing 100 full-color prints will be described.

A color image was formed by performing the same operation as described in the second embodiment. However, the rotation of the photosensitive member was stopped every 10 seconds for forming a color image in order to rest the photosensitive member electrostatically. Was stopped and allowed to stand. Thereafter, the color image forming step was started again. In this way, 100 beautiful color images could be stably obtained continuously even under the condition of the environmental temperature of 40 ° C. (Embodiment 5) Next, the effect of the present invention will be shown using the conventional color printer shown in FIG.

While the photoconductor 8 rotates in the direction of the arrow,
The surface was uniformly charged by the charger 9. Thereafter, the surface of the photoreceptor was irradiated with a laser beam 17 modulated with a signal for forming a first yellow image, thereby forming a latent image. Further, the latent image is first copied to Y
It was developed by the developing device 13 to form a yellow toner image.
By the time the formed yellow toner image comes to a position facing the transfer paper holder 11, one sheet sent from the paper supply unit 18 has already been caught on the outer periphery of the transfer paper holder 11 by the claw 19.
, And the timing is set so that the yellow toner image on the photoconductor comes to a predetermined position on the paper.

After the yellow toner image on the photoreceptor 8 is transferred to a sheet by the action of the transfer charger 20, the surface of the photoreceptor 8 is cleaned by a cleaner 12, where the photoreceptor is electrostatically rested. The discharge of the corona charger 9 was stopped for 3 seconds and the charger was rotated. Thereafter, a magenta image forming step was performed in the same manner as in Yellow. Subsequently, the cyan and black image forming steps were performed after an electrostatic resting step of 3 seconds, similarly to the magenta image forming step. At that time, the developing unit 10 was in a state where each developing device used in accordance with the color was opposed to the photoreceptor so as to be capable of developing. In this way, the four color toner images were transferred onto the paper on the transfer paper holding member 11 and transferred to form a color image on the paper. After transferring the toner images of all colors, the paper was peeled off from the transfer paper holder 11 by the peeling nails 21, and was fixed by the fixing device 23 via the transport unit 22. Thus, a beautiful color image could be stably obtained even under the condition of the environmental temperature of 40 ° C. (Embodiment 6) FIG. 11 shows only the image forming portion of the color electrophotographic apparatus of the present invention. The color digital signal is input to the printer unit and sent to the laser light exposure device 78. The printer unit has four image forming units 79Bk and 7
9C, 79M, and 79Y are arranged in an annular shape so that each of the image forming units can be rotated as a whole so that each image forming unit can sequentially face the transfer paper holding member 80. 81Bk, 81C, 81
M and 81Y are toner hoppers for black, cyan, magenta, and yellow toner, respectively, and are connected to an image forming unit group by a supply pipe (not shown).

Each of the image forming units is made of the same components except for the developer contained therein. Therefore, to simplify the explanation, the image forming unit 79Bk for black will be described, and other colors will be omitted. . FIG. 12 shows the black image forming unit 79Bk. Image forming unit 79Bk
Is an electrophotographic photosensitive drum 83 containing a magnet 82,
A charger 84, a developer hopper 85, a toner collecting electrode roller 87 containing a magnet 86, a two-component developer 89,
It comprises a toner amount regulating plate 90 and a cleaner 91. The position of the magnet 82 is fixed inside the photoconductor 83, and the position of the magnetic pole faces the inner surface of the toner hopper 85.
The photoreceptor 83 is charged to -400 V by the charger 84, and then exposed to laser light 92 to form an electrostatic latent image. The electrostatic latent image thus formed is transferred to the photosensitive member 8 in the developer hopper 85.
The two-component developer 89 is magnetically attracted to the surface of No. 3, and the toner is attached to the surface of the photoconductor 83. The amount of toner adhering to the surface of the photoreceptor 83 is regulated to a thickness of about 0.3 to 3 mm by a toner amount regulating plate 90, and thereafter, a toner collection is provided opposite to the photoreceptor 83 with a gap of about 0.4 mm. It is passed in front of the electrode roller 87. Toner recovery electrode roller 8
A fixed magnet 86 is installed in the inside of the photosensitive member 7. The carrier is attracted to the photosensitive member by applying an AC voltage (frequency: 1 kHz, AC: 1 kVrms, DC bias: -350 V) by an AC high voltage power supply 93. Was visualized as a toner image.

Referring again to FIG. 11, the process of forming a full-color image will be described. Transfer paper (not shown) is fed from a paper feed unit 94 and wound around a transfer paper holder 80 made of a 100 μm-thick polyester film. First, the black image forming unit 79Bk is sent to the image forming position, and the black component signal light is exposed by the laser 95. The formed latent image is visualized in the image forming unit 79Bk, and the toner image is transferred to paper by the operation of the transfer unit 96. This time, the image forming unit group is rotated as a whole, the cyan image forming unit 79C is moved to the position where the black image forming unit is placed, and is replaced with black, and the same image forming process is performed. Using the forming unit 79C, then the magenta unit 79M, and finally using the yellow unit 79Y, a beautiful full-color image was obtained on the transfer paper. Thereafter, the paper was separated from the transfer paper holding member by a pair of separation chargers 97, and finally heat-fixed by a fixing device 98. As a result, a beautiful full-color image was obtained.

Numeral 99 denotes a toner collecting section which collects toner from the cleaner of the image forming unit at the position 79C in the case of FIG. This collection is performed sequentially each time each image forming unit comes to this position. Reference numeral 100 denotes a charger for adsorbing the transfer paper sent from the paper feeding unit 94 to the transfer paper holder 80, and 101 denotes a discharger for discharging the transfer paper holder 80 and the transfer paper during the above-described full-color image forming process. Electric appliances, 1
Reference numeral 02 denotes a cleaner for cleaning the surface of the transfer paper holding member 80 after the completion of image formation.

The above is the description of the color electrophotographic apparatus according to one embodiment of the present invention. In this embodiment, an example in which a two-component developer is used has been described. However, the same effect can be obtained even when at least the black image forming unit uses a magnetic one-component toner.
Although the developing method of forming a developer layer on a photoreceptor in advance has been described as a developing method of each image forming unit, the same effect can be obtained by a normal developing method of forming a developer layer on a developer carrier. Needless to say,

[0047]

According to the present invention moves, the rolling and the exposure position to secure the transfer position and the exposure apparatus of Utsushitai, same image forming position a plurality of image forming units sequentially with a developing unit and the photosensitive member and, the configuration for transferring a toner image onto the rolling Utsushitai, construction is simple and compact color electrophotographic method and apparatus are obtained.

Further, according to the present invention, at the time of color copying, a toner image of each color is aligned using a transfer drum.
At the time of single-color copying, an image is formed by the same operation as a general single-color apparatus without using a transfer drum, so that a color electrophotographic apparatus having a high single-color copying speed can be obtained.

Further, according to the present invention, a stable image can be obtained without fatigue or temperature rise of the photoreceptor even during continuous use.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first conventional color electrophotographic apparatus.

FIG. 2 is a schematic configuration diagram of a second conventional color electrophotographic apparatus.

FIG. 3 is a configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 4 is a configuration diagram illustrating a configuration of an image forming unit using the one-component toner of the present invention.

FIG. 5 is a configuration diagram illustrating a configuration of an image forming unit using the two-component developer of the present invention.

FIG. 6 is a configuration diagram illustrating a state in a color mode of the color electrophotographic apparatus according to the embodiment of the present invention.

FIG. 7 is a configuration diagram illustrating a state in a single color mode of the color electrophotographic apparatus according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram of an image forming unit according to the embodiment of the present invention.

FIG. 9 is an explanatory diagram showing a waveform of a voltage applied to the toner collecting electrode roller of the present invention.

FIG. 10 is an explanatory diagram showing a transition of the charging potential of the photoconductor of the present invention.

FIG. 11 is a configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 12 is a configuration diagram of a black image forming unit.

[Explanation of symbols]

 42Bk, 42Y, 42M, 42C Image forming unit 43 Photoreceptor 44 Magnet 45 Charger 48 Toner hopper 52 Toner regulating plate 53 Toner recovery electrode roller 54 AC high-voltage power supply 58 Laser exposure device 64 Transfer charger 76 Fixing device

──────────────────────────────────────────────────続 き Continued on the front page (31) Priority claim number Japanese Patent Application No. 3-175079 (32) Priority date Hei 3 (1991) July 16 (33) Priority claim country Japan (JP) (56) References JP-A-63-188159 (JP, A) JP-A-60-239786 (JP, A) JP-A-54-108640 (JP, A) JP-A-63-191165 (JP, A) (JP, U) (58) Field surveyed (Int. Cl. ⁶ , DB name) G03G 13/01 G03G 15/01-15/01 117

Claims (7)

(57) [Claims] A plurality of image forming units which are movable and have at least a photosensitive member and a developing device, and transfer a toner image.
A transfer member, becomes more and exposure means, the developing units of the respective image forming units is a color electrophotographic apparatus having a plurality of color toners, and the image forming unit first opposed to the rolling Utsushitai A color electrophotographic apparatus having an image forming position and a separate second image forming position. 2. A plurality of image forming units which are movable and have at least a photoconductor and a developing unit, and transfer a toner image.
A transfer body, comprising an exposure unit, wherein each developing unit of each image forming unit is a color electrophotographic apparatus having a plurality of color toners, and the color electrophotographic apparatus has a color mode and a single color mode, the color mode to move the respective image forming units to the first image forming position in order, after developing with toner to form an electrostatic latent image on the photosensitive member of the image forming unit by said exposure means, said rolling Utsushitai to form a color image by transferring the sequential color toner images on top, whereas the monochromatic mode a toner image one monochromatic developed by the imaging unit in the second image forming position, using the rolling Utsushitai Without
A color electrophotographic device that transfers a toner image to an image receiving paper . 3. A plurality of image forming units which are movable and have at least a photosensitive member and a developing device, and transfer a toner image.
A transfer member, becomes more and exposure means, said a developing units of each image forming unit color electrophotographic apparatus having a plurality of color toners, and the color electrophotographic apparatus in the rolling Utsushitai <br/> a first image forming position of the facing, and a second image forming position remote from the rolling Utsushitai, the exposure means first acting on said image forming unit of the first image forming position in the color mode A color electrophotographic apparatus capable of switching between a state described above and a second state acting on the image forming unit at the second image forming position in the monochrome mode. 4. A color electrophotographic method for forming a color image by synthesizing single-color images of a plurality of colors, wherein T is a photoconductor usage time in each of the single-color image forming steps of color image formation. A color electrophotographic method of forming a color image by repeating the process of T <t, where t is the time for electrostatically resting the photoreceptor until use of the body. 5. A color electrophotographic method in which the same image is continuously formed a plurality of times, wherein a single color image of a plurality of colors is synthesized, and the photosensitive member is electrostatically charged during continuous use of color image formation. A color electrophotographic method, characterized by providing a resting step. 6. A plurality of image forming units having at least a photosensitive member and a developing device, a transfer member for transferring a toner image ,
Be more a single exposure device, the developing units of the respective image forming units has a plurality of color toners, a color electrophotographic apparatus and the exposure position is fixed transfer position and the exposure device of the rolling Utsushitai When forming a color image, the image forming unit group rotates as a whole, and each image forming unit sequentially moves to the same image forming position, and the photosensitive member of the image forming unit is statically moved using the exposure device. A color electrophotographic apparatus that forms an electro-latent image, develops it with color toner, and then transfers the toner image onto the transfer body to form a color image. 7. An image forming unit comprising: an electrophotographic photosensitive member including a fixed magnet; a developer hopper; a developer collecting electrode;
After forming an electrostatic latent image on the photoconductor, the magnetic developer is magnetically attracted to the surface of the photoconductor located in the developer hopper, and the magnetic developer is 7. The color electrophotographic apparatus according to claim 6 , wherein a developer is attached, the photosensitive member is moved, unnecessary developer is collected on the developer electrode, and an image on the photosensitive member is visualized.