JP2001083769A - Color image recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small sized color image recorder with a simple constitution, where a beautiful color image is obtained and with a superior ability to be maintained. SOLUTION: In this device, each developing unit provided with toner of different colors can be sequentially moved to the same developing position by rotating and moving a whole developing unit group provided with a multiple number of developing units. Developing is carried out on a photoreceptor facing the developing unit at the developing position and the toner image is sequentially transferred to an intermediate transfer belt. A developing hopper part in the developing unit is divided into a 1st hopper 14a and a 2nd hopper 14b and is constituted so that a toner hopper is on top at a developing position. Furthermore, a toner concentration sensor and a mechanism for change over of driving of toner replenishing or operation stop is installed on a main body side and the toner replenishing is controlled. The photoreceptor and the intermediate transfer belt are made into an exchangeable unit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color printer,
The present invention relates to a color image recording apparatus applicable to a color copying machine, a color facsimile, and the like.

[0002]

2. Description of the Related Art In general, 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 has been adopted. As a method of forming this color image, a toner image of each color is sequentially formed on one photoconductor, and the transfer material wound around the transfer drum is rotated to repeatedly oppose the photoconductor, and the color of each color sequentially formed there is formed. A transfer drum system in which toner images are superimposed and transferred, and a plurality of image forming units are arranged side by side, and each color toner image is sequentially transferred to a transfer material conveyed by a belt or the like by passing through the position of each image forming unit. In general, a continuous overlapping method in which the sheets are overlapped is performed.

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

FIG. 5 shows an outline of the entire configuration of the conventional example, and the configuration and operation will be briefly described below. In FIG. 5, reference numeral 101 denotes a photosensitive member, and
02, a developing unit 103, a transfer drum 104, and a cleaner 105 are provided. The developing unit 103 includes a Y developing unit 106 for forming a yellow toner image, an M developing unit 107 for magenta, and a C developing unit 10 for cyan.
8, a Bk developing unit 109 for black, and the whole is rotated so that each developing unit can be sequentially developed so as to face the photoconductor 101. The toner density is detected by an optical detection means for detecting the toner density on the developing roller at the developing position, and the toner is replenished at another position rotated by 90 ° from the developing position in accordance with the toner density detected value.
When the single color is continuous, the entire unit rotates at the time when the toner density is lowered, and the developing device whose toner density is lowered is moved to the toner supply position to supply the toner. The main body is provided with a toner hopper 118 corresponding to the toner of each developing device, and a mechanism for sending the toner to a toner supply position. Each developing unit is provided with an opening for replenishing the toner sent from the toner hopper 118 and a replenishing mechanism, so that the toner can be replenished at the toner replenishing position when the toner runs short.

During operation, the transfer drum 104 and the photoreceptor rotate at a constant speed in the direction of the arrow while facing each other.

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

Thereafter, the surface of the photoreceptor is irradiated with a laser beam 110 modulated by a signal for forming a first color yellow image.
To form a latent image. Further, this latent image is first developed in the yellow Y developing device 106 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 104, one sheet of the transfer material sent from the sheet feeding unit 111 has already been formed on the outer periphery of the transfer drum 104 with the claw part. The toner image is formed such that the yellow toner image on the photoreceptor is opposed to a predetermined position of the paper and is wrapped around the paper.

After the yellow toner image on the photoreceptor is transferred to the sheet by the operation of the transfer charger 113, the surface of the photoreceptor is cleaned by the cleaner 105 to prepare for the formation of the next color image. Subsequently, magenta, cyan, and black toner images are formed in the same manner. At that time, the developing unit 103 sets each developing unit that uses the color corresponding to the photoconductor to be in a developable state. The diameter of the transfer drum is large enough to allow the longest sheet to be wound and to replace the developing device between the images of each color.

Laser beam 110 for forming images of each color
Is performed at a timing such that the toner images of the respective colors on the photoreceptor and the toner images already transferred onto the paper on the transfer drum are aligned and faced with each other as they rotate. In this manner, the four color toner images are transferred to the transfer drum 10.
4, the image is transferred onto the sheet, and a color image is formed on the sheet. After the toner images of all colors have been transferred, the sheet is peeled off from the transfer drum 104 by the peeling claws 114, the upper toner image is fixed by the fixing device 116 via the transport section 115, and the sheet is discharged out of the apparatus. The above is a brief description of the configuration and operation of the conventional example.

[0010]

In the above configuration, since the toner hopper is provided on the main body side, a complicated mechanism for supplying toner to the developing unit is required, and the apparatus becomes large and complicated. In addition, the developing unit requires an opening for replenishing toner, so toner spills during toner replenishment not only contaminates the main unit, but also causes spills when replacing the developing unit, making replacement difficult. To Further, the toner supply path from the hopper on the main body side to the developing device becomes long, and the toner may be clogged in the supply path due to the environment or the like, and the toner supply may not be performed normally. Further, in the above configuration, when the image is continuously output in a single color and the toner density is reduced, it is necessary to move the developing device to the toner replenishing position, which hinders the continuous output of the image.

In view of the above problems, an object of the present invention is to provide a color image recording apparatus which is simple and compact in construction of a developing section, does not cause toner spill, 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 different color developer, and a plurality of developing units. Moving means for rotating the whole of a substantially circular combination of the fan-shaped developing units in order to sequentially position each of them at the developing position facing the electrostatic image carrier, and developing means for developing the electrostatic image on the electrostatic image carrier. Transfer means for sequentially transferring the toner images of the respective colors to obtain color images, each of the developing units includes a first hopper for storing a developer obtained by mixing a carrier and a toner, and the first hopper and the toner. A second hopper section adjacent to the toner supply section via the replenishing means and containing only the toner, wherein the second hopper in the developing unit is located above the first hopper at the developing position. Kara An image recording apparatus.

Further, according to the present invention, there is provided an electrostatic image carrier, a plurality of developing units each having a developer of a different color, and a plurality of fan-shaped developing units each having a plurality of developing units opposed to the electrostatic image carrier. Moving means for rotating the whole of the substantially circular shape combined with the fan-shaped developing unit for sequentially positioning the toner image in the position, and sequentially transferring each color toner image developed on the electrostatic image carrier to obtain a color image Transfer means,
A single unit that is attached to the main body in proximity to the outer wall of the developing unit when positioned at the developing position and that can detect the toner concentration of the developer of each color in the developing unit sequentially positioned at the developing position. And a first hopper section in which each of the developing units accommodates a developer in which a carrier and a toner are mixed, and a toner hopper adjacent to the first hopper section via a toner replenishing section to detect only toner. A second hopper section for storing, wherein at least a part of the first hopper and a part of the second hopper are located near a rotation center side of the developing unit. Device.

Further, according to the present invention, there are provided an electrostatic image carrier, a plurality of developing units each having a developer of a different color, and a plurality of fan-shaped developing units, each of which is provided with a developing unit opposing the electrostatic image carrier. Moving means for rotating the whole of the substantially circular shape combined by the fan-shaped developing unit in order to sequentially position the toner images, and sequentially transferring the color toner images developed on the electrostatic image carrier to obtain a color image Transfer means,
A single unit that is attached to the main body in proximity to the outer wall of the developing unit when positioned at the developing position and that can detect the toner concentration of the developer of each color in the developing unit sequentially positioned at the developing position. And a first hopper section in which each of the developing units accommodates a developer in which a carrier and a toner are mixed, and a toner hopper adjacent to the first hopper section via a toner replenishing section to detect only toner. A second hopper section for housing, and a means for driving the toner replenishing means in response to a signal from the toner density detecting means is provided on the main body side.

In the above configuration, since the toner hoppers are all included in the developing units of the respective colors and toner is not supplied from the outside, the toner supply mechanism is simple and toner spillage during toner supply occurs. And contamination by toner inside the machine is small. In addition, maintenance can be performed simply by replacing the developing units of each color, so that the user can easily perform maintenance.

Further, in the above configuration, the toner in the toner hopper is accumulated in the toner supply section in the hopper when the unit is located at the developing position while being naturally stirred when the developing unit rotates. Further, there is no need to provide a stirring mechanism in the toner hopper, and the configuration of the developing unit can be simplified. Further, even when the remaining amount of toner in the hopper becomes small, toner is smoothly supplied.

Further, since the toner hopper in the developing unit at the developing position is located above the developer hopper which contains and agitates the developer, toner supply at the developing position can be easily performed. I can do it. Furthermore, since toner density detection and toner replenishment are performed at the developing position, a stable image can be output without lowering the toner density even when a single color is continuously output.

Further, in the above configuration, since the developing unit moves, only one toner density sensor whose position is fixed needs to be used for four developing units, so that the configuration of each developing unit is simplified. In addition, it leads to cost reduction.

Further, in the above configuration, since the toner supply is driven on the main body side, there is no need to provide a complicated mechanism for supplying toner on the development unit side, and the configuration of the development 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,
4 fan-shaped developing units 1B for each color of cyan
k, 1Y, 1M, and 1C constitute a developing unit group, and are arranged in an annular shape as shown in the figure. Reference numeral 2 denotes a photoreceptor / belt unit, which includes a photoreceptor unit and an intermediate transfer unit. Each developing unit is made of the same constituent members except for a developer to be put in the developing unit. Therefore, for simplification of the description, the developing unit for black will be described, and other colors will be omitted. Note that, for each color, the same portions are denoted by the same reference numerals, and if it is necessary to distinguish each color, a character indicating each color is denoted by the reference numeral. FIG. 2 shows the black developing unit 1Bk in detail.

In FIG. 2, reference numeral 14a denotes a first hopper containing a developer in which a carrier and a 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, and 17 is an agitator for toner supply, 18a and 18b. Reference numeral denotes an agitator for transporting the developer in the first hopper 14a to the developing portion.

Reference numeral 19 denotes a rotatable electrode roller made of aluminum, reference numeral 20 denotes a non-rotating magnet coaxially fixed inside, reference numeral 21 denotes an AC high voltage power supply for applying a voltage to the electrode roller 19, and reference numeral 22 denotes a toner on the electrode roller 19. A magnetic blade that regulates the layer thickness. The electrode roller 19 has a diameter of 16 mm
Then, it was rotated in the direction of the arrow at a peripheral speed of 60 mm / s.

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

In the second hopper 14b, 400 g of toner is hermetically stored at the time of assembling the developing unit, and it is possible to output 5,000 originals corresponding to 5% A4 single color without replenishing toner from outside the unit. I have. When the toner in the second hopper 14b runs out, the user only needs to replace the developing unit.

The developing unit shown in FIG. 2 is a black developing unit and also shows the vertical position of the developing unit at the developing position. In the figure, the second hopper 14b containing the toner 25Bk is located above the first hopper 14a, so that the unit can be provided inside the second hopper 14b without providing a feed mechanism or a stirring mechanism for moving the toner. The toner is supplied to the vicinity of the opening 15 by the rotation and the weight of the toner, and the toner can be smoothly supplied.

Reference numeral 28 denotes a cover for protecting the electrode roller 19, and FIG. 2 shows a state opened for development. When the developing unit is located at a position other than the developing position, the cover 28 holds the electrode roller 1 carrying the developer.
9 to prevent contamination due to developer dust and the like and contamination inside the apparatus due to toner when the unit rotates.

Other developing units 1Y, 1M, other than black
1C has a similar configuration and operates.

Referring again to FIG. 1, the configuration of the printer unit will be described. Reference numeral 9 denotes an organic photoreceptor in which phthalocyanine is dispersed in a polycarbonate-based binder resin, 10 denotes a charging roller for negatively charging the photoreceptor, 13 denotes a signal beam by a laser beam, and 27 denotes cleaning of toner remaining on the photoreceptor surface after transfer. It is a cleaner. Developing units 1Bk, 1Y, 1M, and 1C arranged in a ring form a support (not shown).
As a whole, is driven by a moving motor 30 as a moving means controlled by a control circuit 29, and is rotatable in a direction indicated by an arrow around a cylindrical fixed and non-rotating shaft 31. . Each developing unit is sequentially moved to a developing position 50 facing the photoconductor 9. The support of the developing units 1Bk, 1Y, 1M, and 1C has a means (not shown) for detecting that each developing unit has moved to the developing position 50. Each time the movement of each unit is completed, the movement is completed. The corresponding signal is transmitted to the control circuit 29.

Reference numeral 3 denotes a laser exposure device, which is a signal light 13 of a laser beam modulated by a signal input to a printer unit.
And irradiates the photosensitive member 9 to form a latent image.

Numeral 60 denotes a magnetoresistive toner concentration sensor installed on the shaft 31 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 thickness of the side wall of the developing unit corresponding to the position of the toner density sensor 60 is set thin so that the toner density can be stably detected. Further, in order to further stabilize the detection, the side wall of the unit corresponding to this sensor may be changed to a material having good smoothness and strength even though it is thin. In this embodiment, the toner concentration sensor 60 is fixed without using the separation / contact mechanism, but the position of the toner concentration sensor 60 is slightly shifted to the inside of the rotation when the unit is rotated using the separation / contact mechanism. A configuration in which a separation / contact mechanism may be used, or a configuration in which a spring member or the like is used to press against the side wall of the unit from behind may be used. Further, in this embodiment, the toner density sensor 60 is of a magnetoresistive type. However, for this sensor, for example, an optical reflection density sensor or the like may be used in which the corresponding side wall of the developing unit is transparent. Needless to say.

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

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

Next, the surface of the photoreceptor 9 is set to 400
Developer 2 in a state where layers are opposed and spaced apart by μm
6Bk was passed in front of the electrode roller 19. When the photosensitive member 9 passes through the uncharged area, an AC voltage of 750 V0-p (1.5 kV peak-to-peak) superimposed with a DC voltage of +100 V is applied to the electrode roller 19 by the AC high-voltage power supply 21. Applied. Then, -7
When passing through the surface of the photoreceptor 9 charged with the electrostatic latent image and charged to 00V, the electrode roller 19 is superposed with a DC voltage of -400 V by an AC high-voltage power supply 21 to 750 V0-p (peak-to-peak 1. 5 kV) AC voltage (frequency 1.5 kHz) was applied. As a result, a negative-positive inverted toner image was left only on the image portion on the photoreceptor 9. The carrier and the toner adhered to the electrode roller 19 rotating in the direction of the arrow are returned to the first hopper 14a again and used for the next development.

Thus, a black toner image is obtained on the photoreceptor 9. Reference numeral 32 denotes an intermediate transfer belt, which is a 100 μm-thick endless belt-like film made of semiconductive urethane as a base material, and has a first transfer roller 33 around which a low-resistance treated urethane foam is formed, and a stainless steel transfer belt. It is wound around a roller 34 and is movable in the direction of the arrow.

The first transfer roller 33 is used for the intermediate transfer belt 3
2 and is lightly pressed against the photoconductor 9. Roller 34
The second transfer roller 35 having the same configuration as the first transfer roller 33 is lightly pressed by the intermediate transfer belt 32 so as to be driven and rotatable.

Intermediate transfer belt 32 and second transfer roller 35
A paper transport path is formed in the pressed nip portion so that the paper is sent from the paper supply unit 36.

Reference numeral 40 denotes a belt cleaner section including a belt cleaner for cleaning the intermediate transfer belt. The waste toner collected by the belt cleaner unit 40 is sent to the photoconductor cleaner 27 via a waste toner conveying pipe 37.

The photoreceptor / belt unit 2 includes a photoreceptor 9,
The configuration includes the charging roller 10, the photoconductor cleaner 27, the intermediate transfer belt 32, the first transfer roller 33, the roller 34, the waste toner conveying pipe 37, and the belt belt cleaner section 40, so that it can be easily replaced.

Reference numeral 44 denotes a fixing unit for fixing the toner image on the sheet after the transfer, and reference numeral 45 denotes a discharge roller for discharging the sheet after the fixing.

The above is the description of the main structure 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 located at a position as shown in FIG. 1, the developing unit 1Bk for black is located at a developing position 50 facing the photoreceptor 9, and a toner density is provided on a side wall of the developing unit. The sensor 60 is positioned so as to be almost in 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. At the same time as the development is started, the toner concentration sensor 60 starts detecting the toner concentration of the developer in the first hopper 14a,
The toner supply is performed according to the detection signal.

FIG. 3 shows a driving section of the toner supply agitator 17 of the unit under development. 70 is a gear for rotating the agitator 17, and 71 is a gear 7 provided on the main body side.
The reference numeral 72 denotes a motor for driving 0, and 72 denotes a gear for transmitting the drive of the motor 71 to the gear 70. When toner is supplied in accordance with the output of the toner density sensor 60, the motor 71 rotates, a driving force is transmitted to the agitator 17 via the gears 72 and 70, the agitator 17 rotates, and the Is supplied into the first hopper 14a. When the developing unit group is rotationally moved, the gear 72 is separated from the gear 70, and can be connected when the movement of the unit group is completed. In the present embodiment, a motor for supplying toner is newly provided on the main body side. However, the drive may be transmitted from a driving unit provided on the main body side for another purpose, such as a motor for driving a photoconductor. . In this case, the drive control of the agitator 17 can be easily performed by providing a drive separation / contact means such as a clutch during the transmission of the drive.

As shown in FIG. 2, the lid 16 in the developing unit is rotatably fixed to one side by a hinge so as to open only when a force is applied from the second hopper 14b side, and is opened when no force is applied. A torsion spring (not shown) is attached to close the part 15. Further, the agitator 17 is configured to push open the lid 16 while stirring the surrounding toner to supply the toner. With this configuration, toner replenishment is performed according to a signal from the toner density sensor 60. Actually, the toner density detection is started three seconds after the start of the development so that the detection of the toner density can be performed after the output of the sensor is stabilized. Agitator 17 when toner supply is not performed
Is stopped at a position where the lid 16 cannot be pushed open. In addition, when the developing unit is not developing, especially when the developing unit is moved to a place other than the developing position, the lid 16 is provided with a lock mechanism (not shown) provided on a support (not shown) of the developing unit. (Not shown) to prevent the toner from entering the first hopper from the second hopper at times other than the time of toner replenishment.

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

Developing unit group 1Bk, 1Y, 1M, 1C
The whole is driven by the movement motor 30 to rotate integrally in the direction of the arrow in FIG. 1 and stops at the position where the developing unit 1Y reaches the developing position 50 by just rotating by 90 degrees, and the developing unit 1Y is positioned. . Since the portion other than the electrode roller 19 of the developing unit is located inside the rotating arc at the tip of the electrode roller 19, the photoconductor 9 does not contact the developing unit. Also, the cover 28 of the electrode roller 19
Each of the developing units is opened according to the movement before being positioned at the developing position 50 and can be stored in the developing unit as shown in FIG. 2, and is closed again when the movement is completed after the development is completed. As before, the laser exposure device inputs signal light to the developing unit 1Y based on the yellow signal, and the yellow toner image is formed and transferred. At this time, the timing of writing the yellow signal light is controlled such that the next yellow toner image is positionally matched with the black toner image previously transferred onto the intermediate transfer belt 32. During this time, the second transfer roller 35 and the belt cleaner section 40 are slightly separated from the intermediate transfer belt, and do not act on the toner image thereon.

The same operation as described above is performed for magenta and cyan, and the four color toner images are superimposed on the intermediate transfer belt in a position-matched manner to form a color image. After the transfer of the final cyan toner image, the four color toner images are collectively transferred to the sheet sent from the sheet feeding unit 36 at the same time by the action of the second transfer roller 35. The toner image transferred to the paper is fixed by the fixing device 44. Thereafter, the sheet is discharged out of the apparatus via a discharge roller 45. The transfer residual toner remaining on the intermediate transfer belt 32 is cleaned by the operation of the belt cleaner unit 40 to prepare for the next development.

Next, the operation in the monochrome mode will be described. In the single color mode, first, a developing unit of a predetermined color is moved to a developing position and positioned. Next, development of a predetermined color and transfer to the intermediate transfer belt are performed in the same manner as before, and this time, the transfer is continued as it is, and then transferred to the sheet sent from the sheet supply unit by the next second transfer roller. To go.

Next, maintenance of the apparatus will be described with reference to FIG. It is assumed that the developer of a specific color is no longer consumed 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 of the target color is moved to the upper position (the developing unit in FIG. 1). 1C). 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 outside of 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 spills 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 hindered by related members such as a transfer portion and is not positioned, so that it can be easily taken out of the apparatus. And maintainability is excellent.

For the photoreceptor / belt unit 2, the operator is notified of the replacement time by displaying on the panel of the main body that the life of the unit has expired. The operator opens the front door 47 based on this display, removes the used photoconductor / belt unit 2, and mounts a new unit. 4
Reference numeral 8 denotes a shutter that covers a portion where the photoconductor 9 of the photoconductor / belt unit 2 contacts the electrode roller 19 of the developing unit.
Reference numeral 9 denotes a shutter that covers a portion where the intermediate transfer belt 32 of the photoreceptor / belt unit 2 contacts the second transfer roller 35.
The shutter 49 closes when the front door 47 is opened, and the shutter 48 closes when the photoconductor / belt unit 2 is removed from the main body. This allows
An operator can replace the photoconductor / belt unit 2 without touching the intermediate transfer belt and without spilling waste toner.

The above is the description of the configuration and operation of the embodiment.
In this configuration, the intermediate transfer member is used. However, the essence and the function and effect of the present invention are not changed even when a transfer method such as a transfer drum method in which paper is wound directly onto paper is used.

In the above-described embodiment, a specific developing method is used for the developing unit. However, if a method of mixing a carrier and a toner is used, a developing unit having a structure using another developing method may be used. However, the essence and effect of the present invention do not change.

[0055]

As described above, according to the present invention, the developing units are completed independently as one developing unit for each color, and the structure is simplified without requiring a complicated toner supply mechanism. Further, the photoconductor unit and the intermediate transfer belt unit are also unitized, so that the user only has to replace the developing unit and the photoconductor belt unit of each color, and the maintenance property is excellent.

In addition, each developing unit is configured so that toner can be easily replenished, and only one toner concentration sensor and toner replenishing mechanism need to be mounted on the main body for each of the four developing units. The configuration is simplified.

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

[Brief description of the 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 a color electrophotographic apparatus according to an embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating drive transmission of a toner supply unit of the color electrophotographic apparatus according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram when the developing unit and the photoconductor / belt unit are replaced.

FIG. 5 is a configuration diagram of a conventional color image forming apparatus.

[Explanation of symbols]

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

Claims (7)

[Claims] 1. 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 placed in a developing position facing the electrostatic image carrier. Moving means for combining the fan-shaped developing units to rotate and moving the substantially circular whole, and transferring means for sequentially transferring each color toner image developed on the electrostatic image carrier to obtain a color image, A first hopper unit in which each of the developing units stores a developer in which a carrier and a toner are mixed; and a second hopper unit adjacent to the first hopper unit via a toner supply unit and storing only toner 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 placed in a developing position facing the electrostatic image carrier. Moving means for rotating and moving the substantially circular whole formed by combining the fan-shaped developing units for positioning, and transferring means for sequentially transferring each color toner image developed on the electrostatic image carrier to obtain a color image; A unit that is mounted on the main body in proximity to the outer wall of the developing unit when the developing unit is positioned at the developing position and that can detect the toner concentration of the developer of each color in the developing unit sequentially positioned at the developing position; One toner concentration detecting unit, each of the developing units is adjacent to a first hopper unit that stores a developer in which a carrier and a toner are mixed, and the first hopper unit is adjacent to the first hopper unit via a toner replenishing unit; A second hopper section for storing only toner, wherein at least a part of the first hopper and a part of the second hopper are located near a rotation center side of the developing unit. Color image recording device. 3. The color image recording apparatus according to claim 2, wherein said toner replenishing means is located near a rotation center side of said developing unit. 4. The color image recording apparatus according to claim 2, wherein said toner density detecting means is located near an outer side of a rotation center of said 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 is moved to a developing position facing the electrostatic image carrier. Moving means for rotating the substantially circular whole formed by combining the fan-shaped developing units in order to sequentially position, and transferring means for sequentially transferring each color toner image 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 sequentially mounted at the developing position, which is mounted on the main body in proximity to the outer wall of the developing unit when the developing unit is positioned at the developing position. A single toner concentration detecting unit, each of the developing units is adjacent to a first hopper unit for storing a developer in which a carrier and a toner are mixed, and the first hopper unit is adjacent to the first hopper unit via a toner replenishing unit A second hopper section for storing only the toner, and a means for driving the toner replenishing means in accordance with a signal from the toner concentration detecting means provided on the main body side. . 6. A color image recording apparatus according to claim 5, wherein said means for driving said toner replenishing means is a driving / separating means provided on a main body side. 7. The color image recording apparatus according to claim 5, wherein the toner density detection and the toner replenishment are performed at a developing position.