JPH09258555A - Image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To surely suppress the deterioration of image quality due to a deteriorated developer and to prevent soiling due to scattering at the time of recovering the deteriorated developer by easily realizing a trickling system while satisfying the demand such as the miniaturization and simplification of a device. SOLUTION: This device is provided with toner/carrier supplying means 5 for supplying each color-component toner and carriers into developing means 4 (4a to 4b) respectively and a deteriorated developer recovering means 6 discharging/recovering the deteriorated developer in each developing means 4 from the discharge ports 7 of each developing means 4. At this time, as the deteriorated developer recovering means 6, a path in a rotary shaft 9 which is extended in an axial direction is formed in the rotary shaft of a rotary holder 3, the path in the rotary shaft 9 is connected to and made to communicate with a single recovering space part 8 and the discharge ports 7 of each developing means 4 are connected to and made to communicate with the path in the rotary shaft 9 of the rotary holder 3. A forcedly carrying means 10 is formed so that the deteriorated developer discharged from the discharge ports 7 of each developing means 4 is carried to the recovering space part 8 through the path in the rotary shaft 9 of the rotary holder 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image forming apparatus such as an electrophotographic copying machine and a printer, and more particularly to an image forming apparatus provided with a plurality of developing means using a two-component developer composed of toner and carrier. Regarding improvement.

[0002]

2. Description of the Related Art In an image forming apparatus such as an electrophotographic copying machine or a printer, an electrostatic latent image on a latent image carrier such as a photosensitive drum is visualized by a developing device. Among these types of developing devices, the type employing the two-component developing method uses a two-component developer composed of toner and carrier, and the toner is consumed by the developing operation, but the carrier is not consumed without the carrier being consumed. Remains. Therefore, the carrier stirred together with the toner in the developing device deteriorates as the stirring frequency increases.

In order to suppress the deterioration of the developer,
A so-called trickle developing method has already been adopted (for example, see Japanese Patent Publication No. 2-15991). In this trickle developing method, aside from replenishing the toner consumed by the developing operation, a new carrier is replenished in the developing device,
Drain the excess developer in the developing device due to replenishment,
By successively repeating the operation of supplying and discharging the developer, the deteriorated developer in the developing device is replaced with newly supplied toner and carrier, and the developing characteristics of the developer in the developing device are kept constant. To maintain. As a result, it is possible to maintain the charging performance of the developer and suppress a decrease in copy image quality.

On the other hand, in recent years, demands for color copying machines and printers have increased. In an image forming apparatus such as a copying machine or a printer, in order to obtain a color image, a plurality of color toner images are sequentially formed on a latent image carrier,
A method of sequentially or collectively superimposing the toner images of a plurality of colors on a transfer medium such as paper is adopted. In such a color image forming apparatus, a rotary holder in which a plurality of developing devices for respective color components are mounted on a rotary holder, and the necessary developing devices are arranged to face the latent image carrier by rotating the rotary holder. A developing device (so-called rotary system) is used, or a plurality of image forming units (including a latent image carrier, a developing device, a cleaning device, etc.) for forming toner images of respective color components are arranged in parallel, Various methods such as a so-called tandem method of sequentially transferring a toner image by each image forming unit onto a transfer medium such as an intermediate transfer body have been proposed and put into practical use.

Here, as a prior art in which a so-called trickle system is employed in a rotary developing device, a developing device accommodating a deteriorated developer is rotationally moved to a developer collecting position.
There has been proposed a developing device in which the developing roller of the developing device is rotated in the reverse direction to collect the deteriorated developer in the developing device into a collecting container, and that a new developer is periodically replaced (for example, Japanese Patent Application Laid-Open No. HEI 2 (1994) -208,1992). 208676).

Further, as a prior art in which a so-called trickle system is adopted in a so-called tandem type image forming apparatus, a developer recovery path forming member is arranged below the developing device of each image forming unit and is discharged from each developing device. It has been proposed to collect the deteriorated developer thus collected into a collection container through a developer collection path (for example, JP-A-7-17528).
No. 6).

[0007]

Certainly, Japanese Patent Laid-Open No. 2-2
In both of the prior arts disclosed in JP-A-08676 and JP-A-7-175286, a means for collecting deteriorated developer is provided for each developing device of the rotary developing device or each developing device of each image forming unit. Since it is not necessary to provide the developing device, it is possible to say that each developing device itself does not unnecessarily increase in size and the device configuration is simplified. However, in the prior art disclosed in JP-A-2-208676, in order to collect the deteriorated developer in each developing device of the rotary developing device, the corresponding developing device is moved to the developer collecting section, Moreover, since a special operation (reverse rotation of the developing roll) is required for recovery, it is necessary to secure a recovery cycle for the deteriorated developer separately from the image forming cycle, which lowers the image forming work efficiency. At the same time, there is a technical problem that control of the operation of collecting the deteriorated developer becomes troublesome and that the deteriorated developer is scattered when the deteriorated developer is discharged to the recovery container and the surroundings are easily contaminated.

Further, in the prior art disclosed in Japanese Patent Application Laid-Open No. 7-175286, for example, with respect to the cleaning device of each image forming unit, a recovery means for the residual developer must be provided for each cleaning device, In addition to complicating the apparatus configuration, it is necessary to check the collected state of the residual developer for each cleaning device, which makes maintenance work of the cleaning device troublesome.

The present invention has been made to solve the above technical problems, and an object of the present invention is to reduce the size and simplification of an image forming apparatus having a rotary developing device. An object of the present invention is to provide an image forming apparatus capable of easily realizing a trickle system while satisfying, reliably suppressing deterioration of image quality due to a deteriorated developer, and avoiding contamination due to scattering at the time of collecting the deteriorated developer.
Another object of the present invention is to provide an image forming apparatus having a plurality of image forming units arranged in parallel, which can easily realize a trickle system while satisfying the demands for downsizing and simplification of the apparatus, and to use the deteriorated developer. An object of the present invention is to provide an image forming apparatus that surely suppresses deterioration of image quality and improves workability of maintenance and inspection of the apparatus.

[0010]

That is, in order to achieve the first object, according to the present invention, as shown in FIG. 1, in the vicinity of a latent image carrier 1 on which an electrostatic latent image is carried, a rotation is performed. Holder 3
A rotary developing device 2 having a plurality of developing means 4 (for example, 4a to 4d) mounted therein is provided, each developing means 4 accommodates a two-component developer consisting of toner and carrier, and a rotary holder 3 is provided. By intermittently rotating, each developing means 4 is selectively arranged at a portion facing the latent image carrier 1, and each color component latent image on the latent image carrier 1 is toner-developed by the corresponding developing means 4. In the image forming apparatus, toner / carrier replenishing means 5 for replenishing each color component toner and carrier in each developing means 4 and deteriorated developer in each developing means 4 are discharged from the discharge port 7 of each developing means 4 and collected. The deteriorated developer collecting means 6 is provided, and as the deteriorated developer collecting means 6, a passage 9 extending in the axial direction within the rotation shaft of the rotation holder 3 is provided.
And the passage 9 in the rotary shaft and the single recovery space portion 8 are connected to each other, and the discharge port 7 of each developing means 4 and the passage 9 in the rotary shaft 3 of the rotary holder 3 are connected to each other. It is characterized in that the deteriorated developer discharged from the discharge port 7 of the developing means 4 is provided with a forced transfer means 10 for transferring the deteriorated developer to the recovery space portion 8 through the rotation shaft inner passage 9 of the rotary holder 3.

Further, in order to achieve another object, according to the present invention, as shown in FIG.
(For example, 11a to 11d) are arranged in parallel, a latent image carrier 1 that carries an electrostatic latent image in each image forming unit 11, and a latent image formation that forms an electrostatic latent image on the latent image carrier 1. Means 12, one or a plurality of developing means 4 for accommodating a two-component developer and developing an electrostatic latent image on the latent image carrier 1, and a transfer medium 13 for transferring one or a plurality of toner images on the latent image carrier 1. And a cleaning means 15 for removing the residual developer on the latent image carrier 1, and one or a plurality of toner images formed by each image forming unit 11 are transferred to the transfer medium 13 (final Image forming apparatus for sequentially transferring not only a transfer medium but also an intermediate transfer medium), toner / carrier replenishing means 5 for replenishing each color component toner and carrier in each developing means 4, and each developing means 4 Deteriorated developer inside The developing unit 4 includes a deteriorated developer collecting unit 6 that is discharged and collected from the discharge port 7 of the developing unit 4, and a residual developer collecting unit 17 that collects the residual developer in the cleaning unit 15 by discharging it from the discharge port 16. In order to commonly use the deteriorated developer collecting means 6 and the residual developer collecting means 17, a common collecting duct 18 extending corresponding to the places where the developing means 4 and the cleaning means 15 are arranged is provided,
A single recovery space portion 8 is connected to the common recovery duct 18, and the common recovery duct 18 and each developing means 4 are connected.
The discharge port 7 of the cleaning means 15 and the discharge port 16 of each cleaning means 15 are connected to each other, and the deteriorated developer discharged from the discharge port 7 of each developing means 4 and the residual developer discharged from the discharge port 16 of the cleaning means 15 are connected to each other. It is characterized in that a forced transfer means 19 for transferring to the recovery space section 8 through the common recovery duct 18 is provided.

In such technical means, the toner
The carrier replenishing means 5 may be a mode of replenishing toner and carrier separately, or a mode of replenishing a developer in which toner and carrier are appropriately mixed. Here, in the mode of replenishing the developer composed of toner and carrier, a fixed amount of carrier is mixed in the toner cartridge for replenishing toner consumed by development, in addition to the replenishing toner. It is desirable to replenish the developer.

Further, the operation timing of the toner / carrier replenishing means 5 may be appropriately selected on the basis of the detection information of the developing density for which the replenishing operation is required and the deterioration information of the developer. On the other hand, regarding the timing of the deteriorated developer recovery operation of the deteriorated developer recovery means 6, the deteriorated developer that has become excessive due to the replenishment of the toner carrier may be discharged and recovered, or The deteriorated developer may be discharged and collected at the same time as or before the replenishment of the toner carrier based on the deterioration information of the developer. Here, as for the deterioration information of the developer, the deterioration degree of the developer may be estimated based on, for example, a count value of the number of formed images, or the deterioration degree of the developer may be detected in some form (for example, charging characteristics). May be detected).

Further, from the viewpoint of surely avoiding scattering of the deteriorated developer and the residual developer, a communication connecting portion between the passage 9 in the rotating shaft, the discharge port 7 of the developing means 4, and the recovery space portion 8, and It is preferable to keep the airtightness of the common recovery duct 18, the discharge port 7 of the developing unit 4, the discharge port 16 of the cleaning unit 15, and the communication connecting portion of the recovery spacer unit 8 as good as possible.

Next, the operation of the above technical means will be described. First, in the image forming apparatus shown in FIG.
The toner / carrier replenishing means 5 replenishes the developing means 4 with toner and carrier of each color component. On the other hand, the deteriorated developer collecting means 6 discharges the deteriorated developer in each developing means 4 from the discharge port 7 and collects it in the collecting space section 8. At this time, the discharge port 7 in each developing means 4 is connected to the rotary shaft inner passage 9 of the rotary holder 3, and the recovery space portion 8 is connected to the rotary shaft inner passage 9 so that each developing means. The deteriorated developer in 4 is guided to the rotation shaft passage 9 of the rotation holder 3,
It is recovered in the recovery space section 8 by the forced transfer means 10 arranged in the passage 9.

Next, in the image forming apparatus shown in FIG. 2, the toner / carrier replenishing means 5 replenishes each color component toner and carrier into each developing means 4. On the other hand, the deteriorated developer collecting means 6 and the residual developer collecting means 17 discharge the deteriorated developer in each developing means 4 from the discharge port 7, and discharge the residual developer of each cleaning means 15 from the discharge port 16. Then, it is collected in the collection space section 8. At this time, the discharge port 7 of each developing unit 4 and the discharge port 1 of each cleaning unit 15
Since 6 is connected to the common recovery duct 18 and the recovery space section 8 is connected to the common recovery duct 18, the deteriorated developer in each developing means 4 and the residual developer in each cleaning means 15 are It is guided to the common recovery duct 18 and is recovered in the recovery space section 8 by the forced transfer means 19 arranged in the common recovery duct 18.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below in detail based on the embodiments shown in the accompanying drawings. First Embodiment FIG. 3 shows a first embodiment of a color image forming apparatus to which the present invention is applied. In the figure, reference numeral 21 is a latent image carrier such as a photosensitive drum, 22 is a uniform charging device for precharging the latent image carrier 21, and 23 is an electrostatic latent image written on the charged latent image carrier 21. An exposure device such as a laser scanning device, 24 is rotatably mounted with a black developing device 24a, a yellow developing device 24b, a magenta developing device 24c, and a cyan developing device 24d each having a developer of each color. Predetermined developing units 24a to 24 are provided at the developing position facing the image carrier 21.
A rotary developing device in which d is rotated intermittently, 25 is a transfer device for transferring each color toner image on the latent image carrier 21 to a transfer material 26 such as paper or a transparent sheet, and 27 is a latent image transfer device for facilitating cleaning processing. A pre-cleaning charging device that removes or charges the image carrier 21 before the cleaning step, 28 a cleaning device that removes residual toner on the latent image carrier 21, 29 a charge remover that removes residual charges on the latent image carrier 21. A device, 30 is a fixing device for fixing an unfixed toner image on the transfer material 26.

Further, reference numerals 31 and 32 are transfer material supply trays for supplying the transfer material 26 of a predetermined size, and 33 is the transfer device 2.
5 is a registration roll that regulates the supply timing of the transfer material 26 to the transfer material 5.
6 is a conveyance guide member for conveying and guiding 6 to the fixing device 30.

Further, in the present embodiment, the transfer device 2
Reference numeral 5 denotes a transfer drum 251 having an insulating sheet stretched around the peripheral surface thereof and rotating in a predetermined direction. The transfer material 26 is attached to the transfer material 251 at an adsorption site upstream of the transfer site of the transfer drum 251 in the rotational direction. Charging device 25 for electrostatic attraction
2. Adsorption charging rolls 253 are arranged with the transfer drum 251 interposed therebetween, and the transfer drum 2 corresponding to the transfer portion is provided.
A transfer charger 254 is provided in the printer 51, and a peeling static eliminator 255 for peeling the transfer material 26 from the transfer drum 251 is arranged at a peeling portion of the transfer drum 251 downstream of the transfer portion in the rotation direction. The transfer drum 251.
A pair of static eliminators 256 and 257 on the downstream side of the rotation direction of
And a cleaning device 258 for removing residual paper dust and the like on the transfer drum 251 are provided further downstream of the transfer drum 251 in the rotation direction. Further, in the present embodiment, a reference signal is taken out from a position sensor (not shown) every time the transfer drum 251 makes one revolution, and a rotary holder drive device 42 (see FIG. 6) is driven at an appropriate timing.

Further, in the present embodiment, as shown in FIGS. 3 to 6, in the rotary developing device 24, each of the developing devices 24a to 24d (in the present embodiment, the two-component developing device) is attached to the rotatable rotary holder 41. The rotary holder 41 is rotationally driven by the rotary holder drive device 42 so that the developing devices 24a to 24d are selectively arranged at the developing positions facing the latent image carrier 21. It has become.
Each of the developing devices 24a to 24d has a developing housing 43 in which a portion facing the latent image carrier 21 is opened, as shown in FIGS.
The developing roller 44 is arranged at a position facing the opening of the developing roller 3 and the developing housing 43 adjacent to the developing roller 44.
A pair of developer agitating and conveying augers 45 and 46 are disposed inside, and a developer layer thickness regulating member 47 is disposed apart from the developing roll 44 on the front side of the developing portion of the developing roll 44. . Reference numeral 48 is a developer replenishing cartridge attached to the outside of the developing housing 43.

In the present embodiment, the rotary holder drive device 42, in particular, as shown in FIG. 6, rotates the rotary shaft 51 of the rotary holder 41 via the drive transmission gear 422 through the drive force of the drive motor 421 capable of rotating in the forward and reverse directions. It is designed to be transmitted to. In FIG. 6, reference numeral 423 is an encoder that controls the rotation operation of the drive motor 421 by counting the number of slits of the slit disk fixed to the shaft of the drive motor 421.

Further, the developing roll 44 is, for example, a magnet roll in which a plurality of magnetic poles are arranged fixedly provided in a rotatable developing sleeve, and the developing sleeve contacts or does not contact the latent image carrier 21. They are arranged in contact with each other. Here, as the magnet roll, for example, a magnet having an equal magnetic force, for example, 8 poles, in which N poles and S poles are alternately arranged at intervals, is used. It may be supplied or N
For example, a 7-pole structure may be used in which the poles and the S poles are alternately arranged at intervals, and the portion corresponding to the developer peeling portion is formed so as to have a repulsive magnetic field. Further, the two developer agitating / conveying augers 45 and 46 are also conveying members that also serve as agitating members that rotate in mutually opposite directions, and the toner replenished from the developer replenishing cartridge 48 by the thrust of the agitating screw. And carrying the magnetic carrier,
By the mixing action of the toner and the magnetic carrier, a homogeneous two-component developer triboelectrically charged is produced.
Furthermore, the developer layer thickness regulating member 47 has a double structure composed of, for example, a magnetic material and a non-magnetic material,
The developing roll 4 is disposed at a position substantially facing one magnetic pole of the developing roll 4.
4 is used to form a developer having a uniform layer thickness.

Further, the developer replenishing cartridge 48 has a toner cartridge for replenishing the toner consumed by the development in which a developer in which a fixed amount of carrier is mixed in addition to the replenishing toner is put, for example, as shown in the figure. An external toner concentration sensor supplies a developer to each of the developing devices 24a to 24d so that the concentration of the developed toner image always falls within an appropriate range required for development.

In particular, in this embodiment, as shown in FIGS. 4 to 6, the rotary shaft 51 of the rotary holder 41 is formed with a passage 52 extending in the axial direction, and the rotary shaft 51 has a passage 52 formed therein. A flange-shaped rotary plate 53 is attached to the peripheral edge on one end side, a developer recovery box 54 is fixed to the rotary plate 53, and the rotary shaft inner passage 52 and the developer recovery box 54 are connected to a connecting duct 55. Are linked together. In FIG. 6, reference numeral 56 is a developing device detector that optically detects which of the developing devices 24a to 24d is located at the developing set position.

On the other hand, the rotary shaft 5 of the rotary holder 41 among the peripheral walls of the developing housing 43 of each of the developing devices 24a to 24d.
A discharge port 61 for discharging the excess developer in the developing housing 43 is provided at a position facing the first side. In the present embodiment, the opening position of the discharge port 61 is set to a position exceeding the normal developer storage amount M (see the dotted line in FIG. 5) of the developing device 24a set at the developing position. .

Then, the outlet 61 (specifically 61a to 61d) of each of the developing devices 24a to 24d and the rotary holder 4 are provided.
A connecting duct 62 is provided between the first rotary shaft passage 52 and the first rotary shaft passage 52.
(Specifically, 62a to 62d) are connected for communication.
In the present embodiment, the connecting duct 62 extends straight from the outlet 61 of the developing housing 43 to the linear duct portion 621, and extends outward in the radial direction of the rotary shaft 51 of the rotary holder 41 with respect to the linear duct portion 621. And a bent duct portion 622 that is bent and arranged in a substantially U shape.
Moreover, the connecting duct portion of the bent duct portion 622 to the rotating shaft 51 is arranged so as to be inclined so as to avoid the extended position of the straight duct portion 621.

Further, the transport auger 5 is provided in each of the rotary shaft passage 52 and the straight duct portion 621 of the connecting duct 62.
7, 63 are provided, and the auger 5 for carrying these is provided.
7, 63 are rotationally driven by using a drive transmission system such as a drive source of the developer stirring and conveying augers 45, 46 and a gear.

Next, the image forming process of the color image forming apparatus according to this embodiment will be described. First, the surface of the latent image carrier 21 such as the photosensitive drum is uniformly charged with the negative polarity by the charging device 22. Next, the laser scanning device (exposure device) 23 performs image exposure corresponding to the first color, for example, a black image, and an electrostatic latent image corresponding to the black image is formed on the surface of the latent image carrier 21. At this time, in the rotary developing device 24, the black developing device 24a faces the latent image carrier 21 before the tip of the electrostatic latent image corresponding to the black image reaches the developing position, and then the black developing device 24a. 24a rotates and the magnetic brush rubs the electrostatic latent image to form a black toner image on the latent image carrier 21.

On the other hand, the transfer material 26 such as paper or a transparent sheet is conveyed from the tray 31 or 32, and once its front end is blocked by the registration roll 33,
It is sent to the transfer drum 251 at a predetermined timing. The transfer material 26 sent out is transferred to the transfer drum 2 by an adsorption device (adsorption charger 252, adsorption charging roll 253).
Electrostatically held by 51, the transfer drum 251 and the latent image carrier 21 are conveyed to a transfer area facing each other. Therefore, the transfer material 26 is brought into close contact with the black toner image on the latent image carrier 21, the black toner image is transferred onto the transfer material 26 by the action of the transfer charger 254, and the transfer drum 251 holds the transfer material 26. Ready for the next step.

By the way, the latent image carrier 21, which has completed the transfer of the black toner image, is then subjected to cleaning pretreatment, if necessary, and then the cleaning device 28.
As a result, the black toner remaining on the surface of the latent image carrier 21 is scraped off, and the charge remaining on the surface is removed by the charge removing device 29.

Next, for the second color, for example, a yellow image forming step, the surface of the latent image carrier 21 is uniformly charged by the charging device 22 to a negative polarity, and the laser scanning device 23.
Thus, image exposure corresponding to the yellow image is performed, and an electrostatic latent image of the yellow image is formed on the surface of the latent image carrier 21.
Further, the rotary developing device 24 is switched so that the yellow developing device 24b faces the latent image carrier 21 after the formation of the black toner image is completed, and the electrostatic latent image corresponding to the yellow image is formed. The image is developed with a yellow magnetic brush. Then, the transfer material 26 held on the transfer drum 251 is conveyed to the transfer area again, and the transfer charger 2
Due to the action of 54, the yellow toner image is transferred multiple times this time on the black toner image. After the transfer of the yellow toner image, the latent image carrier 21 is subjected to cleaning of the residual toner on the surface and removal of the residual charges in the same manner as in the black image forming step, while the transfer of the yellow toner image is performed. The transfer material 26 that has been subjected to the process is held in the transfer drum 251 for the next step.

Thereafter, similar to the yellow image forming process, the third color, for example, magenta image forming process is performed, and finally the fourth color, for example, cyan image forming process is performed. After being separated from the transfer drum 251 by the peeling static eliminator 255 and a peeling finger (not shown) at the tip of the conveyance guide member 34, the multiple toner image is fixed on the transfer material 26 by the fixing device 30, and then is transferred to the outside of the image forming apparatus. Be shipped. Further, in the transfer drum 251, which has completed the separation of the transfer material 26, the surface thereof is the static eliminator
After the charge is removed by 6, 257, the cleaning device 258 cleans the surface and waits for the next supply of the transfer material 26.

In particular, in the present embodiment, the replenishment and discharge operations of the developer are performed as follows in the image forming process as described above. That is, when the image forming process as described above is repeated, the developing devices 24a to 24a
The toner in the developer housed in the developing housing 43 of d is gradually consumed, and the ratio of the toner to the carrier, that is, the toner concentration decreases. This change in toner density is detected by a toner density sensor (not shown).
Based on this detection output, feedback control is performed so that the toner density always falls within an appropriate range required for development. By the above control, the toner in the developer replenishing cartridge 48 is supplied from the replenishing port 481 into the developing housing 43 of each of the developing devices 24a to 24d.

On the other hand, the carrier in the developer in the developing housing 43 is not consumed by the development, but is agitated together with the toner in the developing housing 43, the magnetic force of the developing roll 44, and the latent image. The surface and the like are gradually contaminated and deteriorated due to the influence of contact with the carrier 21. When the carrier deteriorates in this manner, a predetermined charge amount cannot be given to the toner, and the image quality deteriorates. However, in this embodiment, when the toner concentration decreases, a new developer is supplied from the developer supply cartridge 48 into the development housing 43, so that not only the toner but also the carrier is supplied into the development housing 43.

Now, for example, assume that the developing device 24a is set at the developing position. At this time, when a new developer is replenished to the developing device 24a, the deteriorated developer in the development housing 42 is normally stored in the developer accommodating amount M as the capacity of the developer 24a increases.
And is discharged from the discharge port 61 to the straight duct portion 621 of the connecting duct 62. Then, this straight duct portion 621
The deteriorated developer is conveyed by the conveying auger 63 inside, and the bent duct portion 62 located below the linear duct portion 621.
It is forcibly led to 2. After that, when the rotary holder 41 rotates and the developing device 24a set at the developing position rotationally moves by 90 ° in the direction of the arrow, the deteriorated developer accumulated on the bent duct 622 naturally falls downward, It is guided to the passage 52 in the rotating shaft. In this state, the deteriorated developer is collected by the transport auger 57 in the rotation shaft inner passage 52 through the rotation shaft inner passage 52 into the developer collection box 54.
Due to the process of recovering the deteriorated developer, the developer in the developing housing 43 is in an optimum state in which the deterioration is suppressed as much as possible, so that the image quality is maintained and the deteriorated developer is removed from the recovery route to the outside. There is no concern that the periphery of the rotary developing device 24 will be contaminated with the deteriorated developer.

Second Embodiment FIG. 7 shows a so-called tandem type color image forming apparatus to which the present invention is applied. In the figure, reference numeral 70 denotes an image forming unit for forming toner images of respective color components. Specifically, black (70a), yellow (70b), magenta (70c), and cyan (70d) are used. Has been. The image forming units 70 (70a to 70d) are all arranged in parallel in the horizontal direction, and a latent image carrier 71 such as a photosensitive drum and a charging device 72 that charges the latent image carrier 71 are charged. An exposure device (not shown) that writes an electrostatic latent image on the latent image carrier 71, a developing device 73 that develops the electrostatic latent image formed on the latent image carrier 71 with corresponding color toner, and a latent image carrier. A transfer device 74 such as a corotron that transfers the toner image on the image carrier 71 onto a transfer material (not shown).
And a cleaner 75 of, for example, a blade cleaning system for removing the residual developer on the latent image carrier 71. Further, reference numeral 76 is a transfer material conveying belt which sequentially conveys the transfer material to the transfer portion of each image forming unit 70, and is circulated and rotated by being wound around a driving roll and an appropriate number of driven rolls. The transfer device 74
Is disposed on the back side of the transfer material transport belt 76.

Further, in the present embodiment, as shown in FIGS. 7 and 8, the developing device 73 has the same structure as the first embodiment.
A developer replenishing cartridge 80 similar to the above is attached. On the other hand, each image forming unit 70 (70a to 70d)
Below the side portions of the developing device 73 and the cleaner 75, a common collecting duct 81 is provided along the arrangement direction of the image forming units 70.
Is provided, and a developer recovery box 82 is connected in communication with one end of the common recovery duct 81 in the longitudinal direction. The housings of the developing device 73 and the cleaner 75 are provided with outlets 83, 84 at the bottoms, for example, and connecting ducts 85, 86 are provided between the outlets 83, 84 and the common recovery duct 81. Further, the auger 87 for transporting the developer is connected in the common recovery duct 81.
Are arranged along the axial direction of the common recovery duct 81 up to the vicinity of the developer recovery box 82.

Further, in the present embodiment, rotary type opening / closing valves 88, 89 are arranged at the outlets 83, 84 of the developing devices 73, cleaners 75, respectively.
The reference numeral 8 temporarily opens in synchronization with the timing when the developing device 73 is replenished with the developer, and discharges the deteriorated developer in the developing device 73, while the open / close valve 89 synchronizes with the open / close valve 88. It is opened temporarily to discharge the residual developer in the cleaner 75. And the transport auger 87
Starts to rotate in synchronism with the opening operation of the opening / closing valves 88 and 89, and for a certain period of time after the opening / closing valves 88 and 89 are closed (at least the developer farthest from the developer collecting box 82 is the developer collecting box 82). It stops after a certain amount of time).

Next, the operation of the color image forming apparatus according to this embodiment will be described. Now, when each of the image forming units 70a to 70d forms each color component toner image, each color component toner image is sequentially transferred to the transfer material conveyed by the transfer material conveying belt 76, and finally passes through a fixing device (not shown). Then, it is fixed on the transfer material. When such an image forming process is repeated and the toner image density of each of the image forming units 70a to 70d decreases, the developer supply cartridge 8
The developer is replenished into the corresponding developing device 73 from 0, and the toner density is controlled to be constant.

At this time, the on-off valves 88 and 89 are temporarily opened, and the excessive deteriorated developer in the developing device 73 and the residual developer in the cleaner 75 drop into the common recovery duct 81 through the connecting ducts 85 and 86, respectively. Common recovery duct 81
It is recovered in the developer recovery box 82 by the transporting auger 87 therein.

Third Embodiment FIG. 9 shows the present invention applied to a color image forming apparatus using an intermediate transfer belt. In the figure, reference numeral 90 is two image forming units for forming two color component toner images, and specifically, for black and yellow (90
a), magenta and cyan (90b) are used. The image forming units 90 (90a, 90b) are all arranged in parallel in the horizontal direction, and a latent image carrier 91 such as a photosensitive drum, a charging device 92 for charging the latent image carrier 91, and a charging device 92 are charged. An exposure device (not shown) for writing an electrostatic latent image on the latent image carrier 91, and a plurality of developing devices 93 for developing the electrostatic latent image formed on the latent image carrier 91 with corresponding color toners, 94, a primary transfer roll 95 that transfers the toner image formed on the latent image carrier 91 to an intermediate transfer belt, which will be described later, and a cleaner 9 that removes residual developer on the latent image carrier 91, for example, by a blade cleaning method.
6 is provided. Further, in the present embodiment, the intermediate transfer belt 98 is stretched around each of the primary transfer rolls 95 of each of the image forming units 90 (90a, 90b) and another appropriate number of driven rolls 97, corresponding to the driven rolls 97. A secondary transfer roll 99 is arranged on the surface side of the intermediate transfer belt 98.

Further, the developer replenishing / collecting device in this embodiment is substantially the same as that in the second embodiment, and as shown in FIG. 9, the developer replenishing cartridge 80 is provided in each of the developing devices 93 and 94. While each developing device 9 is attached
A common recovery duct 81 similar to that of the second embodiment is provided below the side portions of the cleaners 3, 94 and the cleaner 96, and communicates with the developer recovery box 82. The same components as those in the second embodiment are designated by the same reference numerals as those in the second embodiment, and the description thereof is omitted here.

Therefore, according to the color image forming apparatus according to the present embodiment, each of the image forming units 90a, 90
In b, the charging, exposing and developing processes are repeated twice for each color component to form two color toner images on the latent image carrier 91. Then, the color component toner images of the image forming units 90a and 90b are transferred to the intermediate transfer belt 98 through the primary transfer roll 95.
Then, the toner images of the respective color components on the intermediate transfer belt 98 are collectively transferred onto the transfer material 100 and fixed by a fixing device (not shown). Even in such an image forming process, each image forming unit 90 (90a, 90a,
90b) each developing device 93, 94 is replenished with a new developer according to the toner density, while each developing device 93, 9
The deteriorated developer in 4 and the residual developer in the cleaner 96 are discharged to the common recovery duct 81 at a predetermined timing, transported by the transport duct 87, and recovered in the developer recovery box 82.

[0044]

As described above, according to the present invention, in the image forming apparatus having the rotary developing device, the rotary shaft of the rotary holder is deteriorated without the original recovery operation of the deteriorated developer. Since it is used as a developer recovery space, and the deteriorated developer in each developing device can be easily discharged and recovered, the trickle system can be easily realized, and the deterioration of image quality due to the deteriorated developer can be surely suppressed. Therefore, it is possible to maintain a stable high image quality that is essential for color development for a long period of time, and it is possible to effectively avoid contamination due to scattering at the time of collecting the deteriorated developer. Further, since it is not necessary to provide a complicated recovery path for the deteriorated developer for each developing device, it is possible to suppress an increase in cost, an increase in size of the rotary developing device, and a reduction in reliability due to a complicated configuration.

Further, according to the present invention, in an image forming apparatus in which a plurality of image forming units are arranged in parallel, a system for discharging and recovering the deteriorated developer from the developing means and the residual developer from the cleaning means of each image forming unit. Since it is shared, the trickle system can be easily realized and the deterioration of image quality due to the deteriorated developer can be surely suppressed, so that it is possible to maintain the stable high image quality necessary for color development for a long period of time. In addition, the maintenance and inspection work of the developer for the developing means and the cleaning means becomes unnecessary, so that the maintenance and inspection workability for the apparatus can be improved. Further, since it is not necessary to provide a complicated recovery path for the deteriorated developer for each developing means or a complicated recovery path for the residual developer for each cleaning means, the cost is increased and the size of each image forming unit is large. It is possible to suppress a decrease in reliability and the like due to an increase in complexity and a complicated configuration.

[Brief description of drawings]

FIG. 1 is an explanatory diagram illustrating a configuration of an image forming apparatus according to the present invention.

FIG. 2 is an explanatory diagram showing another configuration of the image forming apparatus according to the present invention.

FIG. 3 is an explanatory diagram showing a first embodiment of a color image forming apparatus to which the present invention is applied.

FIG. 4 is an explanatory diagram showing details of the rotary developing device used in the first embodiment.

5 is an explanatory diagram showing details of a rotation holder of FIG. 4 around a rotation axis.

FIG. 6 is an explanatory diagram showing a configuration of a rotary shaft portion of the rotary holder used in the first embodiment.

FIG. 7 is an explanatory diagram showing a second embodiment of a color image forming apparatus to which the present invention is applied.

FIG. 8 is an explanatory diagram showing details of a developer discharging / collecting device according to a second embodiment.

FIG. 9 is an explanatory diagram showing a third embodiment of a color image forming apparatus to which the invention is applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Latent image carrier, 2 ... Rotating developing device, 3 ... Rotating holder, 4 (4a-4d) ... Developing means, 5 ... Toner / carrier replenishing means, 6 ... Degraded developer collecting means, 7 ... Discharge port, 8
... collection space section, 9 ... rotary shaft passage, 10 ... forced transport means, 11 (11a to 11d) ... image forming unit, 1
2 ... Latent image forming means, 13 ... Transfer medium, 14 ... Transfer means,
15 ... Cleaning means, 16 ... Ejection port, 17 ... Residual developer collecting means, 18 ... Common collecting duct, 19 ... Forced conveying means, 21 ... Latent image carrier, 24 ... Rotating developing device, 24
a to 24d ... Developing device, 41 ... Rotation holder, 48 ... Developer supply cartridge, 51 ... Rotation shaft, 52 ... Rotation shaft inner passage, 54 ... Developer collection box, 55 ... Connection duct, 5
7 ... Transport auger, 61 ... Discharge port, 62 ... Connection duct,
63 ... Conveying auger, 70 (70a to 70d), 90
(90a, 90b) ... Image forming unit, 71, 91 ...
Latent image carrier, 73, 93, 94 ... Developing device, 75, 96
... Cleaner, 80 ... Developer supply cartridge, 81 ... Common recovery duct, 82 ... Developer recovery box, 87 ... Transport auger

Claims (2)

[Claims] 1. A latent image carrier (1) carrying an electrostatic latent image.
In the vicinity of the rotary holder (3), a plurality of developing means (4:
4a to 4d) is mounted on the rotary developing device (2), each developing means (4) stores a two-component developer consisting of toner and carrier, and the rotary holder (3) is intermittently installed. Each developing means (4) is selectively arranged at a position facing the latent image carrier (1) by rotating the latent image carrier (1) so that each color component latent image on the latent image carrier (1) corresponds to the corresponding developing means (4). ), The toner / carrier replenishing means (5) for replenishing each color component toner and carrier in each developing means (4) and the deteriorated developer in each developing means (4) And a deteriorated developer collecting means (6) discharged and collected from the discharge port (7) of the developing means (4), wherein the deteriorated developer collecting means (6) is inside the rotation shaft of the rotation holder (3). A passage (9) extending in the axial direction is formed in the A single recovery space (8) is connected for communication, and the discharge port (7) of each developing means (4) and the rotary shaft passage (9) of the rotary holder (3) are connected for communication, so that each development is performed. A forced transfer means (10) is provided in which the deteriorated developer discharged from the discharge port (7) of the means (4) is transferred to the collection space part (8) through the in-rotation shaft passage (9) of the rotation holder (3). An image forming apparatus characterized by being installed. 2. A plurality of image forming units (11: 11a)
To 11d) are arranged in parallel and each image forming unit (1
1) includes a latent image carrier (1) carrying an electrostatic latent image, a latent image forming means (12) for forming an electrostatic latent image on the latent image carrier (1), and a two-component developer. Accommodated, latent image carrier (1)
One or more developing means (4) for developing the electrostatic latent image on the top, transfer means (14) for transferring one or more toner images on the latent image carrier (1) to the transfer medium (13), and latent means Each image forming unit (1) is provided with a cleaning means (15) for removing the residual developer on the image carrier (1).
In an image forming apparatus for sequentially transferring one or a plurality of toner images formed in 1) onto a transfer medium (13), toner / carrier replenishing means (replenishing toner of each color component and carrier in each developing means (4) ( 5), the deteriorated developer in each developing means (4) is discharged from the discharge port (7) of each developing means (4) and is recovered, and the cleaning means (15). Residual developer inside the outlet (1
6) Residual developer recovery means discharged and recovered from 6)
7) and corresponding to the location where each developing means (4) and each cleaning means (15) are arranged in order to share the deteriorated developer collecting means (6) and the residual developer collecting means (17). Is provided with a common recovery duct (18), a single recovery space (8) is connected to the common recovery duct (18) for communication, and the common recovery duct (18) and the discharge means of each developing means (4) are discharged. The outlet (7) and the discharge port (16) of each cleaning means (15) are connected in communication, and the deteriorated developer discharged from the discharge port (7) of each developing means (4) and the discharge of the cleaning means (15) The residual developer discharged from the outlet (16) passes through the common recovery duct (18) and the recovery space section (8)
An image forming apparatus, characterized in that a forced conveying means (19) for conveying to is provided.