JPH07114242A - Color electrophotographic device - Google Patents

Abstract

PURPOSE:To provide a small color electrophotographic device which is a simple structure, obtains a beautiful color image and is excellent in maintenance. CONSTITUTION:All of a plurality of developing unit groups having different toners, as a group, are rotated and moved, so that they can move into the same developing position in order. In the developing position, each developing unit carries out development on a photoreceptor which is situated opposite them, and toner images are transferred on an intermediate transfer belt in order. A developing hopper part in each developing unit is divided into a first hopper 14a and a second hopper 14b, and the toner hopper comes to a high point in the developing position. A toner concentration sensor and a drive/ operation stop changeover mechanism for toner replenishment are mounted on a main body, to control the toner replenishment. The photoreceptor and the intermediate transfer belt are in the form of a replacable unit.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color electrophotographic apparatus applicable to color printers, color copying machines, color fax machines and the like.

[0002]

2. Description of the Related Art Generally, in order to form a color image by electrophotography, a method of forming a color image by superposing toner images of yellow, magenta, cyan and black on a transfer material is used. As a method of forming this color image, toner images of respective colors are sequentially formed on one photoconductor, the transfer material wound around a transfer drum is rotated to repeatedly face the photoconductor, and each of the colors of the colors sequentially formed there is formed. A transfer drum method in which toner images are transferred in an overlapping manner, and a plurality of image forming units are arranged side by side, and a toner image of each color is sequentially transferred to a transfer material conveyed by a belt or the like through each image forming unit position. In general, the continuous stacking method is used.

An example of a color image forming apparatus using the former transfer drum system is disclosed in Japanese Patent Laid-Open No. 1-252982.

FIG. 5 shows an outline of the overall configuration of this conventional example, and the configuration and operation will be briefly described below. In FIG. 5, reference numeral 101 denotes a photoconductor, which is opposed to the photoconductor and is the charger 1.
02, a developing unit 103, a transfer drum 104, and a cleaner 105 are provided. The developing unit 103 includes a Y developing device 106 for forming a yellow toner image, an M developing device 107 for magenta color, and a C developing device 10 for cyan color.
8 and a Bk developing device 109 for black, and the entire device rotates so that each developing device can sequentially face the photoconductor 101 to be in a developable state. The toner concentration is detected by an optical detecting means for the toner concentration on the developing roller at the developing position, and the toner is replenished at another position rotated by 90 ° from the developing position according to the toner concentration detection value.
In the case of continuous monochrome, when the toner density decreases, the entire device rotates and the developing device with the decreased toner density is moved to the toner replenishment position to replenish the toner. The main body is provided with a toner hopper 118 corresponding to the toner of each developing device and a mechanism for feeding the toner to the toner replenishment position. Each developing device is provided with an opening and a replenishing mechanism for replenishing the toner sent from the toner hopper 118, and is configured to be able to replenish at the toner replenishing position when the toner is insufficient.

During operation, the transfer drum 112 and the photoconductor are opposed to each other and rotate at a constant speed in the directions of the arrows.

First, when the operation starts, the photosensitive member 101 rotates in the direction of the arrow, and the surface of the photosensitive member 101 is uniformly charged by the charger 102.

Thereafter, on the surface of the photosensitive member, a laser beam 110 modulated with a signal for forming a first color yellow image is formed.
And a latent image is formed. Further, this latent image is first developed by the yellow developing device 106 facing the photoconductor to form a yellow toner image. By the time the formed yellow toner image reaches the position facing the transfer drum 104, one sheet of paper as a transfer material already sent from the paper feeding unit 111 is already on the outer periphery of the transfer drum 104 with the leading end claw portion. The toner image is formed by being gripped by 112 and wound, and the toner image is formed at a predetermined timing so that the yellow toner image on the photoconductor faces and meets the predetermined position.

After the yellow toner image on the photoconductor is transferred to the paper by the action of the transfer charger 113, the surface of the photoconductor is cleaned by the cleaner 105 to prepare for the formation of the next color image. Subsequently, magenta, cyan, and black toner images are also formed in the same manner, but at that time, the developing unit 103 makes each developing device, which is used according to the color, face the photoconductor to be in a developable state. The diameter of the transfer drum is large enough so that the longest sheet of paper can be wound and the developing unit can be exchanged between images of each color.

Laser beam 110 for image formation of each color
The irradiation is performed with a timing such that the toner images of the respective colors on the photoconductor and the toner images already transferred to the paper on the transfer drum are aligned and face each other as the toner rotates. In this way, the four color toner images are transferred to the transfer drum 10.
4 is transferred onto the paper in a superimposed manner to form a color image on the paper. After the toner images of all colors have been transferred, the paper is peeled from the transfer drum 104 by the peeling claw 114, and the upper toner image is fixed by the fixing unit 116 via the conveyance unit 115 and is discharged to the outside of the apparatus. The above is a brief description of the configuration and operation of the conventional example.

[0010]

In the above structure, since the toner hopper is on the main body side, a complicated mechanism for supplying toner to the developing device is required, and the device becomes large and complicated. Further, since the developing device needs an opening for replenishing toner, not only the toner spills when replenishing the toner to contaminate the main body, but also spilling occurs when the developing device is replaced, which makes replacement difficult. To In addition, the toner replenishment path from the hopper on the main body side to the developing device becomes long, and the toner may be clogged in the middle of the replenishment path due to the environment or the like, and the toner replenishment may not be performed normally. Further, in the above configuration, it is necessary to move the developing device to the toner replenishment position when the image is continuously output in a single color and the toner density is lowered, which hinders the continuous output of the image.

In view of the above problems, it is an object of the present invention to provide a color electrophotographic apparatus which has a simple and compact developing unit, does not cause toner spills, and has excellent maintainability.

[0012]

In order to achieve the above object, the present invention provides an electrostatic image carrier, a plurality of fan-shaped developing units each having a developer of a different color, and a plurality of the developing units. Moving means for rotating and moving the entire substantially circular shape combined with the fan-shaped developing unit in order to sequentially position each at a developing position facing the electrostatic image bearing member, and developing means on the electrostatic image bearing member. Transfer means for sequentially transferring the toner images of the respective colors to obtain a color image, each of the developing units has a first hopper portion for storing a developer in which a carrier and toner are mixed, the first hopper portion and the toner. A second hopper portion which is adjacent via a replenishing means and stores only toner, and the second hopper in the developing unit is located above the first hopper at the developing position. Kara It is an electrophotographic apparatus.

Further, according to the present invention, an electrostatic image carrier, a plurality of developing units each having a developer having a different color, and a plurality of fan-shaped developing units are respectively developed to face the electrostatic image carrier. Moving means for rotating and moving the entire substantially circular shape in which the fan-shaped developing units are combined in order to position the toner sequentially, and toner images of respective colors developed on the electrostatic image carrier are sequentially transferred to obtain a color image. Transfer means,
A single unit that is mounted on the main body side near the outer wall of the developing unit when positioned at the developing position, and that can detect the toner concentration of each color developer in the developing unit that is sequentially positioned at the developing position. Toner concentration detection means, each of the developing units, a first hopper portion that stores a developer in which a carrier and toner are mixed, and a toner hopper that is adjacent to the first hopper portion via the toner replenishing means. A second hopper portion to be stored, wherein at least a part of the first hopper and a part of the second hopper are located in the vicinity of the rotation center side of the developing unit. It is a device.

Further, according to the present invention, the electrostatic image carrier, the plurality of developing units each having a developer having a different color, and the plurality of fan-shaped developing units are respectively developed so as to face the electrostatic image carrier. A moving means for rotating the entire substantially circular shape combined by the fan-shaped developing unit to move the toner images to the respective positions sequentially, and the color toner images developed on the electrostatic image carrier are sequentially transferred to obtain a color image. Transfer means,
A single unit that is mounted on the main body side near the outer wall of the developing unit when positioned at the developing position, and that can detect the toner concentration of each color developer in the developing unit that is sequentially positioned at the developing position. Toner concentration detection means, each of the developing units, a first hopper portion that stores a developer in which a carrier and toner are mixed, and a toner hopper that is adjacent to the first hopper portion via the toner replenishing means. A color electrophotographic apparatus comprising: a second hopper portion to be housed therein; and a means for driving the toner replenishing means in response to a signal from the toner density detecting means provided on the main body side.

[0015]

In the above structure, since the toner hoppers are all included in the developing units of respective colors and the toner is not replenished from the outside, the toner replenishment mechanism is simple, and toner spillage occurs when the toner is replenished. And there is little contamination by toner inside the machine. Further, since the maintenance only needs to replace the developing units of respective colors, the user can easily perform the maintenance.

Further, in the above structure, the toner in the toner hopper is naturally agitated when the developing unit is rotationally moved, and is collected in the toner supply section in the hopper when the unit is positioned at the developing position. It is not necessary to provide a stirring mechanism in the toner hopper, and the structure of the developing unit can be simplified. Further, the toner is smoothly supplied even when the toner remaining amount in the hopper becomes low.

Further, since the toner hopper in the developing unit at the developing position is located above the developer hopper which contains the developer and stirs the toner, the toner can be easily replenished at the developing position. You can do it. Further, since the toner density is detected and the toner is replenished at the developing position, a stable image can be output without decreasing the toner density even when a single color is continuously output.

Further, in the above structure, since the developing unit is moved, only one toner density sensor whose position is fixed is used for four developing units, so that the structure of each developing unit is simplified. It leads to cost reduction.

Further, in the above configuration, since the toner replenishment drive is performed on the main body side, it is not necessary to provide a complicated mechanism for replenishing toner on the developing unit side, and the configuration of the developing unit is simplified.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color electrophotographic apparatus according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is an overall configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention. First, black, yellow, magenta,
Four sets of fan-shaped developing units 1B for each color of cyan
k, 1Y, 1M, and 1C form a developing unit group, and are arranged in an annular shape as shown in the drawing. Reference numeral 2 denotes a photoconductor / belt unit, which is configured to include a photoconductor portion and an intermediate transfer body portion. Since each developing unit is made of the same constituent member except for the developer contained therein, the developing unit for black will be described and the other colors will be omitted to simplify the description. Note that, for each color, the same portions are denoted by the same reference numerals, and when it is necessary to distinguish each color, the reference numerals are attached to indicate the respective colors. FIG. 2 shows the black developing unit 1Bk in detail.

In FIG. 2, 14a is a first hopper for containing a developer in which a carrier and toner are mixed, and 14b.
Is a second hopper containing only toner, 15 is an opening opened for toner supply, 16 is a lid for opening and closing the opening 15, 17 is an agitator for supplying toner, and 18a, 18b Is an agitator for transporting the developer in the first hopper 14a to the developing portion.

Reference numeral 19 is a rotatable developing electrode roller made of aluminum, 20 is a non-rotating magnet fixed coaxially in the inside, 21 is an AC high voltage power source for applying a voltage to the developing electrode roller 19, and 22 is on the electrode roller 19. It is a magnetic blade that regulates the toner layer thickness. The electrode roller 19 has a diameter of 1
It was rotated in the direction of the arrow at a peripheral speed of 6 mm and a peripheral speed of 60 mm / s.

In the first hopper 14a, a two-component developer 26 is prepared by mixing a toner carrier 25Bk with a ferrite carrier 24Bk having a particle size of 50 μm, the surface of which is coated with a silicone resin.
Bk was added, and it was attached to the surface of the electrode roller 19 by the conveyance and magnetic force of the agitators 18a and 18b. The toner used is one in which a pigment or the like is dispersed in a polyester resin and an additive is further added. The developer 26BK adhering to the electrode roller 19 is conveyed to the developing field in a state where the layer is regulated by the blade 22 and used for development.

In the second hopper 14b, 400 g of toner is hermetically stored when the developing unit is assembled, and 5000 sheets of A4 monochromatic 5% originals can be output without supplying toner from the outside of the unit. There is. When the toner in the second hopper 14b is exhausted, the user only needs to replace the developing unit.

The developing unit in FIG. 2 is a developing unit for black, and also shows the upper and lower positions of the developing unit at the developing position. In the figure, the developer second hopper 14b containing the toner 25Bk is located above the first hopper 14a. Therefore, the toner hopper 14b does not need to be provided with a feeding mechanism or a stirring mechanism for moving the toner inside the toner hopper 14b. The toner is supplied to the vicinity of the opening 15 by the rotational movement and the own weight thereof, and the toner can be smoothly replenished.

Further, 28 is a cover for protecting the electrode roller 19, which is shown in FIG. 2 in an opened state for development. This cover 28 is used for the electrode roller 1 carrying a developer when the developing unit is located at a position other than the developing position.
9 is configured to prevent contamination of the developer with dust or the like, and contamination of the inside of the machine with toner when the unit is rotationally moved.

The developing devices 1Y, 1M, and 1C other than black have the same structure and operate.

The configuration of the printer unit will be described again with reference to FIG. Reference numeral 9 is an organic photosensitive member in which phthalocyanine is dispersed in a polycarbonate binder resin, 10 is a charging roller for negatively charging the photosensitive member, 13 is a signal light by a laser beam, and 27 is a toner remaining on the surface of the photosensitive member after transfer. It is a cleaner. The developing units 1Bk, 1Y, 1M, and 1C arranged in an annular shape are supports (not shown).
And is driven by a moving motor 30 which is a moving means controlled by a control circuit 29, and is rotatably movable in the arrow direction around a cylindrical fixed shaft 31 that does not rotate. . Each developing unit is sequentially moved to the developing position 50 facing the photoconductor 9. The support of the developing units 1BK, 1Y, 1M, 1C has means (not shown) for detecting that each developing unit has moved to the developing position 50, and the movement is completed each time the movement of each unit is completed. The corresponding signal is transmitted to the control circuit 29.

Reference numeral 3 is a laser exposure device, which is a signal light 13 by a laser beam modulated by a signal input to the printer section.
Is generated and irradiated on the photoconductor 9 to form a latent image.

Reference numeral 60 denotes a magnetic resistance type toner concentration sensor installed on the shaft 31, which is positioned so that the toner concentration in the first hopper 14a of the developing unit can be detected when the developing unit is moved to the developing position 50. ing. The side wall of the developing unit corresponding to the position of the toner concentration sensor 60 has a thin wall thickness so that the toner concentration can be detected stably. Further, in order to further stabilize the detection, the side wall of the unit corresponding to this sensor may be thinned by changing to a material having good smoothness and strength even if it is thin. In this embodiment, the toner concentration sensor 60 is fixed without using the separating / contacting mechanism, but the position of the toner concentration sensor 60 may be slightly shifted inward when the unit is rotated by using the separating / contacting mechanism. A separating / contacting mechanism may be used, or a structure in which a spring member or the like is pressed against the side wall of the unit from the rear side may be used. Further, in this embodiment, the toner density sensor 60 is of the magnetic resistance type, but an optical reflection density sensor or the like may be used for this sensor, for example, by making the corresponding side wall of the developing unit transparent. Needless to say.

Next, the operation of the printer will be described with reference to FIG. The photoconductor 9 has a diameter of 30 mm and a peripheral speed of 60 mm /
It was rotated in the arrow direction with s.

The photosensitive member 9 is charged with the charging roller 10 at -700V.
Charged to. The photoconductor 9 was irradiated with the signal light 13 by the laser beam to form an electrostatic latent image. At this time, the exposure potential of the photoconductor was -100V.

Next, the surface of the photosensitive member 9 is set to the surface of the photosensitive member 9 and 400
Developer 2 in a state in which the layers are opposed to each other and spaced by a distance of μm.
It was passed in front of the electrode roller 19 carrying 6BK. When passing through the uncharged area of the photoconductor 9, an AC high voltage power source 21 applies an AC voltage of 750 V 0-p (peak-to-peak 1.5 kV) superposed with a DC voltage of +100 V to the electrode roller 19 (frequency 1 kHz). Applied. After that, -7
When passing the surface of the photoconductor 9 charged with 00V and having an electrostatic latent image written therein, 750V 0-p (peak-to-peak 1. An alternating voltage (frequency: 1.5 kHz) of 5 kV) was applied. Then, a negative-positive inverted toner image remained only on the image portion on the photoconductor 9. The carrier and toner attached to the electrode roller 19 rotating in the direction of the arrow were returned to the inside of the developer first hopper 14a and used for the next development.

In this way, a black toner image is obtained on the photosensitive member 9. Reference numeral 32 denotes an intermediate transfer belt, which is a transfer roller 33 and a stainless steel roller 34, which are made of an endless belt-shaped film having a semi-conductive urethane base material and have a low resistance treatment formed of urethane foam. It is wound around and can be moved in the direction of the arrow.

The transfer roller 33 is lightly pressed against the photosensitive member 9 via the intermediate transfer belt 32. The transfer roller 33 is connected to the roller 34 via the intermediate transfer belt 32.
The second transfer roller 35 having the same configuration as the above is lightly pressed so as to be driven to rotate.

Intermediate transfer belt 32 and second transfer roller 35
A sheet conveying path is formed in the nip portion which is pressed against the sheet so that the sheet is fed from the sheet feeding section 36.

A belt cleaner 40 includes a belt cleaner for cleaning the intermediate transfer belt. The waste toner collected by the belt cleaner 40 is sent to the photoconductor cleaner 27 via the waste toner carrying pipe 37.

The photoconductor / belt unit 2 includes a photoconductor 9,
Charging roller 10, photoconductor cleaner 27, intermediate transfer belt 32, transfer roller 33, roller 34, waste toner carrying tube 3
7, and the structure including the belt cleaner 40, and can be easily replaced.

Reference numeral 44 is a fixing device for fixing the toner image on the paper after transfer, and 45 is a discharging roller for discharging the paper after fixing.

The above is the description of the main construction of the electrophotographic apparatus and the developing unit of the present invention. Next, the operation of this apparatus during color development will be described.

First, each developing unit is at the position as shown in FIG. 1, the developing unit 1Bk for black is located at the developing position 50 facing the photoconductor 9, and the toner concentration is on the side wall of the developing unit. The sensor 60 is positioned so as to make almost contact as shown. Black signal light is input to the photoconductor 9 by the laser exposure device 3, and development with black toner is performed. Simultaneously with the start of development, the toner concentration sensor 60 starts detecting the toner concentration of the developer in the first hopper 14a,
Toner is replenished according to this detection signal.

FIG. 3 shows the driving portion of the toner replenishing agitator 17 of the unit under development. 70 is a gear for rotating the agitator 17, 71 is a gear provided on the main body side
Reference numeral 72 is a motor for driving 0, and 72 is a gear for transmitting the drive of the motor 71 to the gear 70. When toner is supplied according to the output of the toner concentration sensor 60, the motor 71 rotates, the driving force is transmitted to the agitator 17 via the gear 72 and the gear 70, the agitator 17 rotates, and the inside of the second hopper 14b. Toner is supplied into the first hopper 14a. The gear 72 is separated from the gear 70 when the developing unit group is rotationally moved, and can be connected when the movement of the unit group is completed. In this embodiment, a motor for replenishing toner is newly provided on the main body side, but the drive may be transmitted from a driving means provided on the main body side for another purpose, such as a motor for driving the photoconductor. . In that case, the drive control of the agitator 17 can be facilitated by providing a drive separating / connecting means such as a clutch during the transmission of the drive.

The lid 16 in the developing unit is rotatably fixed to one side by a hinge so that it is opened only when a force is applied from the second hopper 14b side as shown in FIG. 2, and is opened when no force is applied. A torsion spring (not shown) is attached so as to close the portion 15. Further, the agitator 17 is configured to push open the lid 16 while stirring the toner in the surrounding area to replenish the toner. With this configuration, toner replenishment is performed according to a signal from the toner density sensor 60. Actually, the toner concentration detection is started 3 seconds after the start of development so that the sensor output can be stabilized. Agitator 17 when not supplying toner
Is designed to stop at a position where the lid 16 cannot be pushed open. Further, except when the developing unit is developing, especially when the developing unit is moving to a place other than the developing position, the lid 16 is provided with a lock mechanism (see FIG. 3) provided on a support (not shown) of the developing unit. It is locked in a closed state by not shown) to prevent the toner from being mixed into the first hopper from the second hopper except when the toner is being replenished.

The black toner image developed on the photosensitive member 9 is sequentially transferred onto the intermediate transfer belt 32 by the action of the transfer roller 33.

Developing unit group 1Bk, 1Y, 1M, 1C
Is entirely driven by the moving motor 30 to integrally rotate in the direction of the arrow in FIG. 1, rotates exactly 90 degrees, and stops at the position where the developing unit 1Y reaches the developing position 50, and the developing unit 1Y is positioned. . Since the portion of the developing unit other than the electrode roller 19 is located inside the rotating arc of the tip of the electrode roller 19, the photosensitive member 9 does not come into contact with the developing unit. In addition, the cover 28 of the electrode roller 19
2 has a structure in which each developing unit is opened according to the movement before being located at the developing position 50 and can be stored in the developing unit as shown in FIG. 2, and is closed again at the time of movement after the completion of the developing. As before, this time the laser exposure device inputs the signal light to the developing unit 1Y with the yellow signal, and the yellow toner image is formed and transferred. At this time, the writing timing of the yellow signal light is controlled so that the next yellow toner image is positionally aligned with the black toner image previously transferred onto the intermediate transfer belt 32. During this time, the second transfer roller 35 and the cleaner unit 40 are slightly separated from the intermediate transfer belt so that nothing acts on the toner image thereon.

The same operation as described above is performed for magenta and cyan, and four color toner images are positionally aligned and superposed on each other on the intermediate transfer belt to form a color image. After the final transfer of the cyan toner image, the four color toner images are collectively transferred onto the paper fed from the paper feed section 36 at the same timing by the action of the second transfer roller 35. The toner image transferred onto the paper is fixed by the fixing device 44. The sheet is then discharged to the outside of the apparatus via the discharge roller 45. The transfer residual toner remaining on the intermediate transfer belt 32 is cleaned by the action of the cleaner unit 40 to prepare for the next development.

Next, the operation in the monochromatic mode will be described. In the single color mode, first, the developing unit of a predetermined color is moved to the developing position and positioned. Next, as in the previous step, the specified color is developed and transferred to the intermediate transfer belt. This time, after the transfer, the process is continued as it is, and the next second transfer roller transfers the paper to the paper fed from the paper feed section. To go.

Next, maintenance of this apparatus will be described with reference to FIG. It is assumed that the developer of a specific color is consumed and runs out, and maintenance is performed. First, the developing unit group is rotated by the action of the moving motor 30 controlled by the control circuit 29 in response to a command from an operator (by a switch (not shown)), and the developing unit for the color of interest is placed at the upper position (the developing unit in FIG. 1C position). Then, as shown in FIG. 3, the operator opens the cover 46 located at the upper part of the apparatus main body, takes out only the developing unit of interest from the apparatus, and mounts a new developing unit of that color.

At this time, since the electrode roller cover is in the closed state, the worker does not stain his hands with the developer or spill the developer.

Further, since the developing unit to be replaced can be replaced at an upper position different from the developing position, it is not disturbed by related members such as the transfer section and is not positioned, so that it can be easily taken out of the apparatus. It is possible to do so and maintainability is excellent.

Regarding the photoconductor / belt unit 2, the operator is informed of the replacement time by displaying on the panel of the main body that the life of the unit has expired. Based on this display, the operator releases the front door 47, takes out the used photoconductor / belt unit 2, and mounts a new unit. Four
Reference numeral 8 designates a shutter for covering a portion where the photosensitive member 9 of the photosensitive member / belt unit 2 contacts the electrode roller 19 of the developing unit.
Reference numeral 9 denotes a shutter that covers a portion where the belt 32 of the photoconductor / belt unit contacts the second transfer roller 35.
The reference numeral 9 indicates that the front door 47 is opened, and the shutter 48 is closed when the photoconductor / belt unit is taken out from the main body. As a result, the operator can replace the photoconductor / belt unit 2 without touching the intermediate transfer belt and without spilling the waste toner.

The above is the description of the configuration and operation of the embodiment.
Although the intermediate transfer member is used in the present configuration, the essence and effects of the present invention do not change even in a method of directly transferring to a paper such as a transfer drum method in which a paper is wound.

In the above embodiments, a specific developing method was used for the developing unit. However, in the case of a developing unit having a structure using another developing method, a method of mixing carrier and toner is used. However, the essence and effects of the present invention do not change.

[0055]

As described above, according to the present invention, the developing unit is completed independently as one developing unit for each color, and a complicated toner replenishing mechanism is not necessary and the structure is simplified. Further, since the photoconductor portion and the intermediate transfer belt portion are unitized, the user only needs to replace the developing unit and the photoconductor belt unit for each color, and the maintainability is excellent.

Further, each developing unit has a structure capable of easily replenishing toner, and since only one toner concentration sensor and four toner replenishing mechanisms need to be mounted on the main body of the four developing units, the apparatus Simpler configuration.

Since the size of the intermediate transfer member can be reduced, the device can be downsized.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a developing unit used in the color electrophotographic apparatus according to the embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating transmission of drive of a toner replenishing unit according to an embodiment of the present invention.

FIG. 4 is an explanatory view when replacing a developing unit and a photoconductor / belt unit.

FIG. 5 is a block diagram of a conventional color electrophotographic apparatus.

[Explanation of symbols]

 1Bk, 1C, 1M, 1Y Development unit 2 Photoconductor / belt unit 3 Laser exposure device 9 Photoconductor 13 Signal light 28 Electrode roller cover 32 Intermediate transfer belt 33 Transfer roller 35 Second transfer roller 50 Development position 60 Toner density sensor

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI technical display location G03G 15/08 115

Claims (7)

[Claims] 1. An electrostatic image bearing member, a plurality of fan-shaped developing units each having a developer of a different color, and each of the plurality of developing units are sequentially placed at a developing position facing the electrostatic image bearing member. Moving means for rotating the entire substantially circular shape by combining the fan-shaped developing unit for positioning, and transfer means for sequentially transferring the toner images of the respective colors developed on the electrostatic image carrier to obtain a color image, Each of the developing units is provided with a first hopper portion that stores a developer in which a carrier and toner are mixed, and a second hopper portion that is adjacent to the first hopper portion via a toner replenishing means and stores only the toner. When,
A color electrophotographic apparatus, wherein the second hopper in the developing unit is located above the first hopper at the developing position. 2. An electrostatic image carrier, a plurality of fan-shaped developing units each having a developer of a different color, and each of the plurality of developing units are sequentially arranged at a developing position facing the electrostatic image carrier. Moving means for rotating and moving the substantially circular whole as a combination of the fan-shaped developing units for positioning, and transfer means for sequentially transferring the toner images of the respective colors developed on the electrostatic image carrier to obtain a color image The toner concentration of the developer of each color in the developing unit, which is mounted on the main body side in the vicinity of the outer wall of the developing unit when positioned at the developing position and is sequentially positioned at the developing position, can be detected. One toner concentration detecting means, each of the developing units is adjacent to a first hopper portion for storing a developer in which a carrier and toner are mixed, and the first hopper portion via a toner replenishing means. A second hopper portion for accommodating only toner, and at least a part of the first hopper and a part of the second hopper are located in the vicinity of the rotation center side of the developing unit. Color electrophotographic device. 3. The toner replenishing means is located near the center of rotation of the developing unit.
The color electrophotographic apparatus according to 1. 4. The color electrophotographic apparatus according to claim 2, wherein the toner concentration detecting means is located near the outer side of the rotation center side of the first hopper. 5. An electrostatic image carrier, a plurality of fan-shaped developing units each having a developer of a different color, and each of the plurality of developing units are placed at a developing position facing the electrostatic image carrier. Moving means for rotating and moving the entire substantially circular shape combined with the fan-shaped developing unit for sequentially positioning, and transfer means for sequentially transferring the toner images of the respective colors developed on the electrostatic image carrier to obtain a color image And the toner concentration of the developer of each color in the developing unit, which is mounted on the main body side in the vicinity of the outer wall of the developing unit when positioned at the developing position and is sequentially positioned at the developing position, can be detected. A single toner concentration detecting means, a first hopper portion in which each of the developing units stores a developer in which a carrier and toner are mixed, and a first hopper portion and a first hopper portion which are adjacent to each other via a toner replenishing means. And a second hopper portion for accommodating only the toner, and means for driving the toner replenishing means in response to a signal from the toner concentration detecting means is provided on the main body side. . 6. The color electrophotographic apparatus according to claim 5, wherein the means for driving the toner replenishing means is a drive separating / connecting means installed on the main body side. 7. A color electrophotographic apparatus according to claim 5, wherein the toner density detection and the toner replenishment are performed at the developing position.