JPH08328377A - Rotary type developing device - Google Patents

Abstract

PURPOSE: To miniaturize the device, to attain quick change over of a developing device, to stably supply toner and further to efficiently supply toner without lowering productivity even at the time of consecutive printing in monochrome. CONSTITUTION: In this rotary type developing device where plural developing devices 2 are mounted; the developing device 2 is provided with a developer housing chamber 5 housing two-component developer and a toner storage chamber 7 storing the toner for supply and having a toner stirring member 6 disposed inside, and it is equipped with a long sized toner supply chamber 9 at least having small capacity equal to or above the amount of supplying the toner once so as to face to the toner storage chamber 7. A part of the toner supply chamber 9 communicates with the developer housing chamber 5, then a toner supply member 8 is disposed in the toner supply chamber 9. Furthermore, toner supplying operation is executed only to the developing device 2 being at a developing position. The toner stirring member 6 and the toner supply member 8 are individually driven by different driving sources.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a copying machine, a printer, etc.
BACKGROUND OF THE INVENTION Among electrophotographic image forming apparatuses, the present invention relates to a developing device used in a color image forming apparatus that creates a color image by superposing toners of a plurality of colors, and in particular, a plurality of developing devices are mounted on a rotary housing, The present invention relates to an improvement in a rotary developing device that performs development by rotationally moving a desired developing device to a portion of a latent image carrier that faces a developing position.

[0002]

2. Description of the Related Art Conventionally, electrophotographic color image forming apparatuses have been downsized, and have spread not only to special fields but also to general business fields. However, the electrophotographic color image forming apparatus still has a number of problems to be solved or improved. One of them has a developing device that visualizes an electrostatic latent image on a photoconductor. Is to be configured.

Although various means have been proposed as a developing device for an electrophotographic color image forming apparatus, they can be roughly classified into two types. One method is a stationary type in which a plurality of developing devices having developers of respective colors are arranged along the peripheral surface of the photoconductor, and the other method is a rotating body or a linear moving body adjacent to the photoconductor. It is a mobile type in which a plurality of developing devices are mounted on the moving body and the developing devices are switched.

Among such developing devices, the stationary type inevitably has a large photosensitive member, making it difficult to downsize the entire device, and since the position of the developing device is different, parts,
Costs rise because parameters cannot be shared. On the other hand, in the movable type, it is possible to reduce the size of the photoconductor and the apparatus, and the developing position can be shared, so that the parts,
Although it is possible to achieve some degree of commonality of parameters, since the developing device moves, it is necessary to devise various measures in the toner transport section between the replenishment toner storage chamber and the developing device. Many proposals have already been made regarding structure and function.

Conventionally, in a developing device by a magnetic brush developing method using a two-component developer consisting of a toner and a carrier which is a magnetic powder, a toner for replenishing the toner in addition to the developer containing chamber containing the developer. An accommodating chamber is provided, and replenishment toner is accumulated in the toner accommodating chamber so that the toner is automatically replenished in the developer accommodating chamber when the developer in the developer accommodating chamber becomes less than a predetermined concentration. What has been done is proposed. According to this type, in the case of continuously printing a large number of sheets, the toner storage chamber may be made large and a large amount of replenishment toner may be stored, but all are incorporated in the rotary developing device. The entire apparatus becomes huge, and the huge rotary type developing apparatus has a large moment of inertia, and it is extremely difficult to drive and control at high speed, and it is also unrealistic.

Therefore, in the prior art, the toner accommodating chamber can be easily replaced as a cartridge, some kind of toner replenishing and conveying mechanism is provided between the toner accommodating chamber and the developer accommodating chamber, and toner is replenished as needed through the mechanism. Is proposed.

As a method of this kind, a plurality of developing devices (developing units) are mounted on a rotating body, while a plurality of toner containing containers are arranged at positions different from the rotating body, and each toner containing container is installed. And a plurality of developing devices are respectively provided with a toner transport mechanism, and, for example, one developing device that has reached a developer replenishing position at a position different from the developing position on the upstream side of the developing position supplies toner. Proposed (for example, Japanese Patent Publication No.
-8330 gazette and Japanese Patent Publication No. 4-8790 gazette).

According to this method, since it is not necessary to secure a large toner storage space in the rotating body, it is possible to avoid increasing the size of the rotating body and increase the inertia of the rotating body. Instead, since the toner container is provided outside the rotating body, the toner transport path becomes longer, which complicates the toner transport mechanism.In addition, when multiple sheets are continuously printed in the single color mode, the development process is performed. Even if the developer concentration in the agent storage chamber is reduced and toner needs to be replenished, the developing device must be temporarily rotated to a toner replenishment position different from the developing position, which lowers the printing speed and reduces productivity. The technical problem of becoming

As another conventional method for solving such a technical problem, in a rotary type developing device having a plurality of developing devices mounted therein, each developing device has a developing chamber in which a developer is accommodated and a replenishing chamber. A toner chamber containing the toner is provided, and the developing chamber and the toner chamber are partitioned by a partition having a plurality of through holes, and a plurality of through holes corresponding to the through holes of the partition are provided in the vicinity of the partition. It has been proposed that an opened shutter is provided and toner is replenished from the toner chamber to the developing chamber by the swinging motion of the shutter (for example, Japanese Patent Laid-Open No. 61-61160).
-95370 gazette).

However, in this type, since the toner supply method is a shutter function, stable toner supply cannot be performed due to clogging and the shutter is provided over the entire partition wall in the toner chamber. Inevitably, the toner chamber must be enlarged by the space for
Moreover, the inertial weight of the rotating body increases. Further, since the toner chamber is wide and flat, there is a technical problem that it becomes difficult to detect the remaining amount of toner when the remaining amount of the replenishment toner in the toner chamber becomes small.

The present invention has been made in order to solve the above technical problems, and selects a two-component developing method which is superior to the non-magnetic one-component developing method in terms of maintainability and image density uniformity. However, while maintaining good hue variation control and hue uniformity within images when images of different colors are overlapped, the size of the device can be reduced to enable high-speed switching of the developing device and stable toner supply. Further, the present invention provides a rotary developing device capable of efficiently realizing toner replenishment without lowering productivity even when continuous printing is performed in a single color.

[0012]

That is, the present invention provides:
As shown in FIG. 1, a plurality of developing devices 2 (for example, 2a to 2d) are provided in a rotary housing 1 which is driven to rotate intermittently by a driving means.
And a predetermined developing device 2 arranged corresponding to the developing position and developing the electrostatic latent image on the latent image carrier 14 in the rotary developing device, each developing device 2 includes a developer carrying member. 3 and a developer accommodating chamber 5 in which a developer agitating / conveying member 4 for agitating and conveying the two-component developer on the developer carrier 3 is disposed.
And the replenishment toner is stored, and the toner stirring member 6 is internally provided.
And a toner storage chamber 7 in which the toner storage chamber 7 is disposed, and a long toner supply chamber 9 having a small volume equal to or larger than the amount of toner supply at least once is provided at a position facing the toner storage chamber 7. A toner supply member that allows the toner in the toner supply chamber 9 to be supplied to the developer storage chamber 5 while communicating with the developer storage chamber 5 in a part of the toner supply chamber 9. 8 is provided.

In such a technical means, from the viewpoint of simplifying the toner replenishment work without enlarging the toner storage chamber 7 itself, the toner storage chamber 7 should be composed of a replaceable toner cartridge. However, the entire developing device 2 may be replaced by an integral cartridge.

From the standpoint of maintaining good toner replenishment performance in the single color mode, the toner supply member 8 is driven only in the developing device 2 at the developing position, and the toner replenishing chamber 9 to the developer accommodating chamber 5 is driven. It is preferable to execute the toner supply operation. Further, although the driving sources of the toner stirring member 6 and the toner supply member 8 may be shared, the toner stirring member 6 and the toner supply member 8 are different from each other in view of easy drive control. It is preferable to independently drive the toner by the driving source and independently perform the toner stirring operation separately from the toner supply operation. Furthermore, from the viewpoint of smoothly performing the toner replenishment operation at the developing position, for example, the toner in the toner storage chamber 7 with respect to the developing position and the developing device 2 located at least one position before the developing position. It is preferable that the agitating member 6 be driven so that the toner in the toner storage chamber 7 is moved to the toner replenishing chamber 9 side in advance.

Further, as means for more severely suppressing the density fluctuation of each color, and further the hue fluctuation when superposed, a notch portion 11 is provided in a part of the developer accommodating chamber 5 and the toner replenishing chamber 9. The toner supply member 8 is partitioned by the partition walls 10 formed, and has a configuration in which the toner supply member 8 has a spiral blade having a constant outer diameter in the longitudinal direction or having a rotation axis over the entire length, and the spiral blade has an end portion. It is preferable to adopt a configuration in which the groove faces the cutout portion 11. If such a toner supply member is used, the toner replenishment amount can be accurately controlled by the rotation time of constant speed rotation,
Moreover, the density fluctuation of each color can be controlled by using it together with the toner replenishment amount determination method described later. Further, since the spiral blade functions as a wall in the toner conveying direction unless it rotates itself, it is strong against the backflow of the developer when the developing device 2 moves.

Furthermore, the density fluctuation of each color over a long period of time,
As a means to more severely suppress the hue variation when superposed, a flow regulating member for preventing the developer in the developer accommodating chamber 5 from flowing back to the toner replenishing chamber 9 in the vicinity of the cutout portion 11. It is preferable to adopt a configuration in which 12 is provided.

Further, as a method of replenishing the toner into the developer accommodating chamber 5, a counter is provided corresponding to each developing device 2 for totalizing the index indicating the darkness of each pixel in one image formation. A method of replenishing the toner amount corresponding to the count value or a method of developing the reference latent image on the latent image carrier 14 and optically reading the development density to replenish the toner amount corresponding to the difference from the reference development. The method may be selected as appropriate, or a method in which these methods are used in combination may be appropriately selected.

Further, as means for recognizing the time to replace the toner in the toner storage chamber 7, a toner empty detection means 13 is provided for each developing device 2, and when the empty state is detected, the toner storage chamber 7 is detected.
To send the toner replacement signal in the display means,
Alternatively, the count value of the pixel density counter is integrated every time image formation is performed, and when the integrated value reaches a set value, a toner replacement signal in the toner storage chamber 7 is output to the display means, or Even if the operation of developing the reference latent image on the image carrier 14 and optically reading the development density and replenishing the toner amount corresponding to the difference from the reference development density is repeated, the development density of the reference latent image is increased. If there is no toner, a signal for replacing the toner in the toner storage chamber 7 may be displayed on the display means, and the toner may be appropriately selected. In this case,
Regarding the toner empty detecting means 13, the toner storage chamber 7
You can directly detect the residual toner inside, but
From the viewpoint of more accurately detecting the residual toner, it is preferable to provide the toner empty detecting means 13 in the toner replenishing chamber 9.

[0019]

According to the technical means as described above, assuming that the toner in the developer storage chamber 5 of the developing device 2 at the developing position is insufficient, the toner of the developing device 2 at the developing position is assumed. Perform a replenishment operation. In this toner supply operation process, first, the toner stored in the toner storage chamber 7 is pushed to the toner supply chamber 9 side by the stirring operation of the toner stirring member 6, and the toner is covered around the toner supply member 9. To be collected. When the toner supply member 9 performs the toner replenishing operation for a time corresponding to the required replenishment amount, the toner is replenished from the toner storage chamber 7 through the toner replenishment chamber 9 to the developer accommodating chamber 5 while being measured, It is mixed with the developer by the developer agitating and conveying member 4.

Further, since the developer agitating / conveying member 4 is disposed in the developer accommodating chamber 5, even if the developer accommodating chamber 5 is sufficiently separated from the developer carrying member 3, The developer agitating and conveying member 4 surely conveys the developer to the developer carrier 3. Therefore, a sufficient amount of the two-component developer that can be accommodated in the developer accommodating chamber 5 is secured, and the superiority in maintainability with respect to the non-magnetic one-component developing system is maintained. If the developer stirring / conveying member 4 in the developer accommodating chamber 5 is composed of a pair of stirring / conveying members that circulates and moves the developer in the longitudinal direction of the developer carrier 3, the replacement of the developer is effective. Since the developer that has once consumed the toner does not stay in the same region for a long time, the image density uniformity and the hue uniformity in the superimposed image are kept good.

Further, by adopting a construction in which the toner replenishing operation is performed for the developing device 2 at the developing position, even if a large number of sheets are printed in the monochromatic mode and the developing device 2 runs out of developer. The toner replenishing operation is performed at the same position without rotating the developing device 2.

Furthermore, if the toner stirring member 6 in the toner storage chamber 7 is driven at the developing position and at least one position before the developing position, the rotary housing 1 is driven.
Even if is rotated, the toner is pushed and filled in the small-sized long toner supply chamber 9 adjacent to the toner storage chamber 7. Therefore, when the developing position is reached, the developing device 2
When the toner replenishing operation is performed, the toner replenishing chamber 9 retains at least one amount of toner corresponding to the replenishing amount at one time.
A predetermined amount of toner is replenished therein.

When the amount of toner stored in the toner storage chamber 7 becomes insufficient, it goes without saying that the toner is not sufficiently filled in the toner replenishment chamber 9 having a small volume. When the detecting means 13 is provided, the shortage state of the stored toner in the toner storage chamber 7 can be detected more accurately than in the type in which the toner empty detection means 13 is provided in the toner storage chamber 7.

Further, a partition wall 10 having a notch 11 formed in a part of the developer accommodating chamber 5 and the toner replenishing chamber 9 is formed.
And the developer storage chamber 5 in the vicinity of the cutout portion 11.
If the configuration in which the rectifying member 12 for preventing the developer from flowing back to the toner replenishing chamber 9 is provided is adopted, the developer in the developer accommodating chamber 5 will not flow back to the toner replenishing chamber 9 side. Certainly avoided.

If the toner storage chamber 7 of each developing device 2 or each developing device 2 itself is constructed as a replaceable cartridge, the toner replenishing performance for each developing device 2 can be easily maintained by replacing the cartridge. To be done.

[0026]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail with reference to the embodiments shown in the accompanying drawings. FIG. 2 shows an embodiment of a color image forming apparatus to which the invention is applied. In the figure, reference numeral 21 is a latent image carrier such as a photosensitive drum, 22 is a uniform charger for precharging the latent image carrier 21, and 23 is an electrostatic latent image written on the charged latent image carrier 21. Laser exposure device, 24
Is a black developing device 24a having a developer of each color,
A yellow developing device 24b, a magenta developing device 24c, and a cyan developing device 24d are rotatably mounted, and predetermined developing devices 24a to 24a are provided at a developing position facing the latent image carrier 21.
4d is a rotary type developing device which rotates 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 carrier for facilitating cleaning processing. A pre-cleaning charger that removes or charges the image carrier 21 before the cleaning step, 28 is a cleaning device that removes residual toner on the latent image carrier 21, and 29 is a remover that removes residual charge on the latent image carrier 21. An electric device 30 is a fixing device for fixing the unfixed toner image on the transfer material 26. Reference numerals 31 and 32 are transfer material supply trays for supplying the transfer material 26 of a predetermined size, 33 is a registration roll for controlling the supply timing of the transfer material 26 to the transfer drum 251, and 34 is a transfer material after the transfer process is completed. A conveyance guide member that conveys and guides 26 to the fixing device 30.

In this embodiment, the transfer device 25
Has a transfer drum 251 around which an insulating sheet is stretched and rotates in a predetermined direction. The transfer material 26 is transferred to the transfer drum 251 at an adsorption site upstream of the transfer site of the transfer drum 251 in the rotational direction. An electrostatic charger 252 for electrostatic attraction.
Adsorption charging rolls 253 are arranged with the transfer drum 251 interposed therebetween, and the transfer drum 251 corresponding to the transfer portion is provided.
A transfer charger 254 is provided therein, and a peeling static eliminator 255 for peeling the transfer material 26 from the transfer drum 251 is further provided at a peeling portion on the downstream side in the rotation direction of the transfer portion of the transfer drum 251. In addition, a pair of static eliminators 256 and 257 are arranged on the downstream side of the transfer drum 251 in the rotational direction, with the transfer drum 251 interposed therebetween.
A cleaning device 258 for removing the residual paper dust and the like on the transfer drum 251 is disposed further downstream in the rotational direction than the No. 1 unit.

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 is uniformly charged to a negative polarity by the uniform charger 22. Next, with the laser exposure device 23,
For example, image exposure corresponding to a black image is performed, and an electrostatic latent image for the black image is formed on the surface of the latent image carrier 21.

In the rotary developing device 24, the black developing device 24a is arranged to face 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 magnetic developing device 24a is magnetized. The 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 is conveyed from the tray 31 or 32 and once transferred to the registration roll 3
After the leading end of the transfer drum 251 is dammed by 3, the sheet is sent to the tack point of the transfer drum 251 at a predetermined timing. The transferred transfer material 26 is electrostatically held on the transfer drum 251 by a suction charging device 252 and a suction charging roll 253, and is conveyed to a transfer portion where the transfer drum 251 and the latent image carrier 21 face each other. . Therefore, the transfer material 26 comes into close contact with the black toner image on the latent image carrier 21 and the transfer charger 2
The black toner image is transferred onto the transfer material 26 by the action of 54, and the transfer drum 251 prepares for the next step while holding the transfer material 26.

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

Next, for the image forming process of the second color, for example, yellow, the surface of the latent image carrier 21 is uniformly charged to the negative polarity by the uniform charger 22, and the laser exposure device 2 is used.
Image exposure corresponding to the yellow image is performed by 3, and an electrostatic latent image of the yellow image is formed on the surface of the latent image carrier 21. Further, the 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 switched. Is developed with a yellow magnetic brush. Then, the transfer material 26 held on the transfer drum 251 is conveyed again to the transfer portion, and by the operation of the transfer charger 254, the yellow toner image is transferred multiple times on the black toner image this time.

After the transfer of the yellow toner image, the latent image carrier 21 is then cleaned of residual toner on the surface and discharged of residual charges in the same manner as in the black image forming step. The transfer material 26 that has completed the transfer of toner is prepared for the next step while being held by the transfer drum 251.

After that, like the yellow image forming process, the image forming process of the third color, for example, magenta, is performed, and the image forming process of the fourth color, for example, cyan is finally performed, but in the last cyan image forming process. The transfer of the transfer material 26 is different from the steps up to the third color. That is, the transfer material 26 that has finished the transfer of the fourth color is separated from the transfer drum 251 by the peeling static eliminator 255 and the peeling finger (not shown) at the tip of the transport guide member 34, and the multiple toner image is transferred to the transfer material 26 by the fixing device 30. After being fixed on the sheet, it is carried out of the image forming apparatus.

The transfer drum 2 after the transfer material has been separated
The surface of 51 is neutralized by the static eliminators 256 and 257, the surface is cleaned by the cleaning device 258, and the next transfer material 26 is awaited.

Next, the rotary developing device 24 according to this embodiment will be described in detail with reference to FIGS. 3 and 4. In the figure, reference numeral 41 is a rotary housing (rotary support) which is intermittently rotated by a drive system (not shown), and four rotary housings 41 are provided around the rotary shaft 42 every 90 ° as shown. The developing devices 24a to 24d are detachably held. In this embodiment, each developing device 24a-24b
Includes a developer accommodating chamber 51 for accommodating a two-component developer, a toner accumulating chamber 52 for accommodating replenishment toner, and a toner replenishing chamber 53 for replenishing toner from the toner accumulating chamber 52 to the developer accommodating chamber 51. It has been made. Particularly, in this embodiment, the developer accommodating chamber 51 and the toner replenishing chamber 53 are formed in the developing housing 54 which is detachably fixed to the rotary housing 41, while the toner storing chamber 52 is formed in the developing housing 54. It is formed in a cylindrical cartridge 55 that is exchangeably mounted.
A cartridge receiving portion 56 having an arc-shaped cross section is formed in the developing housing 54, and an engaging groove and an engaging ridge engaging with the engaging groove are provided between the cartridge receiving portion 56 and the cylindrical cartridge 55. Coupling mechanism (not shown)
Is formed, and the cylindrical cartridge 55 is replaceably attached to the cartridge receiving portion 56 via this engagement mechanism.

Further, the developer accommodating chamber 51 has a width dimension substantially corresponding to the latent image formable region of the latent image carrier 21, and the developing opening 6 is provided at a position corresponding to the developing position.
1 has been opened. A developing roller 62 is disposed in the developer accommodating chamber 51 so as to face the developing opening 61, and a pair of developer agitating and conveying augers 63 and 64 are arranged along the axial direction of the developing roller 62. It is set up.

Further, in this embodiment, an agitator 65 for stirring is arranged in the toner storage chamber 52,
The agitator 65 is composed of, for example, a bent wire member that rotates and moves along the inner wall surface of the toner storage chamber 52 having a circular cross section. The bent wire member stirs the toner in the toner storage chamber 52 while separating the toner from the inner wall surface. Toner supply chamber 5
The toner is conveyed to the opening of No. 3.

Furthermore, the toner replenishing chamber 53 faces the toner storage chamber 52, and is formed in a long shape having a small volume corresponding to at least one toner replenishing amount. The toner replenishing chamber 53 and the developer accommodating chamber 51 are partitioned by a partition wall 57 having a U-shaped cross section, as shown in FIGS. The developer storage chamber 51 is provided at one end side in the longitudinal direction.
Is formed with a notch portion 58 communicating with. Further, a toner supply auger 66, which is a spiral toner supply member for supplying toner, is disposed in the toner supply chamber 53. 5 is a perspective view of the toner supply chamber 53 on the downstream side of the toner supply auger 66 in the conveyance direction, and FIG.
FIG. 6 is a sectional view taken along line VI-VI in FIG.

Now, in such a basic structure, the detailed structure and function of each part, and the developer and toner will be further described. First, the developing roll 62 has a structure in which a magnet roll (magnetic field generating means) having a plurality of poles magnetized therein is fixedly provided, and the surface thereof is made of aluminum whose surface is sandblasted to about Rz = 5 to 15 μm. The sleeve is rotatably arranged. Here, the outer diameter of the sleeve is φ18 m
Further, the magnetic flux density in the vertical direction on the sleeve surface of the developing electrode is 95 mT, and the surface speed of the sleeve is appropriately selected to be 2 to 3 times the surface speed of the latent image carrier 21. Then, the developing roll 62 is attached to the magnet roll.
It is magnetized so as to form a repulsive magnetic field in the vicinity of the developer agitating / conveying auger 63 arranged on the side, so that the developer once used for development and having a lowered toner concentration is quickly separated from the sleeve surface. ing.

Further, a pair of developer stirring and conveying augers 63,
64 is outer diameter φ17 mm, inner diameter φ8 mm, pitch 20 m
Metallic sleeves are arranged at both ends of a spiral member integrally molded of plastic so as to be m, and constitute a developer circulation path in the developer accommodating chamber 51.
Then, in order to transfer the developer between the developer agitating and conveying augers 63 and 64 at both ends of the developer accommodating chamber 51, one end of each of the developer agitating and conveying augers 63 and 64 is reversed by at least one turn. The spiral part of the pitch is provided. The rotation speed is 180 rpm. The pair of developer agitating / conveying augers 63, 64 are used as the developing devices 24a-2
When 4d rotates, even if there is a local deviation in the amount of developer, it has a function of instantly leveling, and at the same time, it is necessary to quickly prevent the developer whose toner concentration has been lowered once used for development from remaining. Has the function of circulating and transporting.

The developer accommodated in the developer accommodating chamber 51 is obtained by mixing and dispersing a colorant in a polyester resin and internally adding a charge control agent, a transfer aid, a cleaning aid, a fixing aid, etc., if necessary. Alternatively, externally added toner having a weight average particle diameter of 7 μm, and a carrier of ferrite powder having a magnetization of about 60 emu / g in a magnetic field of 1000 Oersted and a weight average particle diameter of 50 μm are used. To
The toner is mixed so as to have a predetermined toner concentration.

Further, each developing device 24a in this embodiment
The drive system of 24d will be described with reference to FIG. In the drawing, the drive roll gears 72 to 64 are respectively attached to the rotary shafts of the developing roll 62, the developer stirring / transporting augers 63 and 64, the agitator 65, and the toner supply auger 66 of each of the developing devices 24a to 24d.
76 is provided, and a drive transmission gear 77 is further interposed between the drive transmission gears 73 and 74. In this embodiment, the drive transmission gears 72, 73, 77, 74, 76 are sequentially meshed with each other, and a clutch CL is provided between the drive transmission gears 74, 76 to connect them during the toner replenishing operation. On the other hand, the drive transmission gear 75 of the agitator 65 is provided independently without meshing with the other drive transmission gears 72 to 74, 76, 77.

Further, in this embodiment, the developing device 24a is now used.
Is in the developing position, the developing unit 24 in the developing position
The toner replenishing operation is executed only for a. That is, for example, when the developing device 24a reaches the developing position, the drive gear 82 connected to the rotation shaft of the drive motor (M1) 81 meshes with the drive transmission gear 72 of the developing device 24a during the toner replenishing operation, and ,
The clutch CL connects both drive transmission gears 74 and 76.
Therefore, in the developing device 24a located at the developing position, the toner supply auger 66 is rotationally driven via the developing roll 62 and the developer stirring and conveying augers 63 and 64. The drive motor (M1) 81 is also used when executing a developing operation. In this case, the connection state by the clutch CL is cut off, and the developing device 24a at the developing position does not perform the developing operation. Only the roll 62 and the developer stirring / transporting augers 63 and 64 are rotationally driven.

Further, in this embodiment, the developing device 24a is now used.
Is at the developing position, the toner stirring operation is performed on the developing position and the developing devices 24a and 24b located immediately before the developing position. That is, the developing device 24a,
In 24b, the drive gear 84 connected to the rotary shaft of the drive motor (M2) 83 is the drive transmission gear 7 of the developing device 24a.
5, the drive gear 86 connected to the rotary shaft of the drive motor (M3) 85 also meshes with the drive transmission gear 75 of the developing device 24b. Therefore, the agitator 65 is rotationally driven at the developing position and the developing devices 24a and 24b located at a position immediately before the developing position.

The drive motors (M1, M2, M3)
Drive gears 82 connected to the rotary shafts of 81, 83, 85,
Reference numerals 84 and 86 are provided so as not to interfere with the rotation operation of the rotary developing device 24, and a drive motor for intermittently rotating the rotary housing 41 is omitted in the drawing.

Next, the toner replenishing operation process in the developing device 24a at the developing position will be described. The toner stored in the toner storage chamber 52 is collected so as to cover the toner supply auger 66 in the toner supply chamber 53 by the rotation of the agitator 65. The toner supply auger 66 rotates at a constant speed for a time corresponding to the required supply amount, so that the toner storage chamber 52 passes through the toner supply chamber 53 and the developer storage chamber 5 while toner is being measured.
1 and is mixed with the developer by the developer agitating and conveying augers 63 and 64. In the present embodiment, the toner supply auger 66 has an outer diameter of 14 mm, an inner diameter of 6 mm, and a resin spiral member integrally molded with a pitch of 13 mm, and shafts are attached to both ends of the spiral member.
Rotate at a rotation speed of 20 rpm. Further, the amount of toner replenished per unit time during rotation is 175 × 10 ⁻³ g / sec.

At this time, for example, in an image forming apparatus in which the surface speed of the latent image carrier 21 is 80 mm / sec, the image density is 100% and the developing toner weight per unit area is 8 g.
5.5 s even if A3 size image formation of / m ² is performed
During the development of ec, the toner can be replenished to sufficiently capture the consumed toner. The latent image carrier 2
The apparatus having a higher surface speed of No. 1 can be dealt with by adjusting the configuration and the rotation speed of the toner supply auger.

Further, in this embodiment, the agitator 65 agitates the toner in the toner storage chamber 52 in the developing device, for example, the developing device 24b, which is one position before the developing position. At this time, the toner in the toner storage chamber 52 is pushed toward the toner supply chamber 53 side to some extent, so that when the developing device 24b reaches the developing position, the stored toner in the toner storage chamber 52 smoothly moves to the toner supply chamber 53 side. Avalanche Therefore, when the developing unit 24b reaches the developing position, the toner is kept sufficiently filled in the toner replenishing chamber 53, and the toner replenishing amount during the toner replenishing operation becomes accurate.

With the above-described basic structure, it is possible to realize local density fluctuation control and secure density uniformity within an image, which are strictly required in full-color development, and a non-magnetic single component is used. By utilizing the advantages of the two-component developing method, which has a longer life than the developing method, it is possible to provide a developing device that can sufficiently deal with the maintenance of the density of the entire image in the short term.

Next, in full-color development, improvements aimed at maintaining the strictly required long-term development density will be described. Concerning the short-term density maintainability, it is possible to maintain a considerable amount by estimating the amount of toner required for replenishment based on test data and the like, and predicting replenishment of the toner with the toner replenishing mechanism having the above-mentioned configuration. However, a higher accuracy is required for a full-color image, which is affected by the accumulation of errors over a long period of time, and which appears particularly as a change in hue, as compared with a single-color image.

In this embodiment, first, in order to make the toner supply amount more accurate, a developer backflow prevention mechanism as shown in FIG. 6 is provided. Specifically, an elastic ring member 91 is provided on the partition wall 57 over at least one pitch of the spiral toner supply auger 66, and the elastic ring member 91 is gently in contact with the toner supply auger 66. Therefore, even if the developing devices 24a to 24d repeatedly rotate, the developer in the developer accommodating chamber 51 remains in the toner replenishing chamber 53.
The spiral toner supply auger 66 can accurately measure and replenish toner in proportion to the rotation time without backflowing to. Therefore, the toner replenishment amount is kept accurate over a long period of time.

As another configuration, if there is enough space, a shutter 92 that can be opened and closed may be provided facing the cutout portion 58, as shown in FIG.

Further, in this embodiment, in order to more accurately predict the replenishment necessary toner amount, as shown in FIG. 9, the total value for all the pixels of the index indicating the density of each pixel of the formed image is calculated for each color. Counters 101 to 104 for counting each component and each image formation are provided, and a method of determining the rotational driving time of the spiral toner supply auger 66 according to the values of the counters 101 to 104 is adopted. There is. In FIG. 9, the counters 101 to 104 are
It is provided in the screen conversion device 100 for converting the image data into the screen data to be sent to the laser exposure device 23, and an index indicating the density of each pixel passing through the image data acquisition unit 105 is set for each color component for every pixel. It has the function of adding up to. Further, the count value is the control device 12 that controls the image output device 110 of the image forming apparatus.
At 0, the rotational drive time of the spiral toner supply auger 66 is converted. This allows
Even if image formation with a high image density and deviating from the standard continues, very accurate toner replenishment can be performed for a long period of time.

Furthermore, as shown in FIG. 10, there is a concern that the image density may change due to frequent changes in the place where the image forming apparatus is installed and the environment in which the apparatus is used may change.
An element (density sensor) 131 for optically reading the amount of toner developed on the electrostatic latent image on the latent image carrier 21 is arranged to face the electrostatic latent image, and the output thereof is taken into the control device 120 to output the output. Corresponding to the developing drive system 80 (drive motor 83
By controlling (M2), 85 (M3) and the clutch CL, the toner replenishment amount, that is, the rotational drive time of the spiral toner supply auger 66 is appropriately corrected. As a result, the accuracy of maintaining the image density is further improved, and there is no problem even when the image density is not used.

Of course, the toner supply amount is determined only by referring to the output from the element 131 that optically reads the toner amount developed on the latent image carrier 21, and the rotation driving time of the toner supply auger 66 is determined. May be. In this case, since it is necessary to set the period for reading the toner amount of the latent image carrier 21 to be considerably short, the number of prints per unit time may decrease depending on the relationship between the transfer drum 251 and the size of the image.

Next, some specific examples of the method of displaying the replacement time of the toner cartridge (cartridge) 55 for further simplifying the maintenance of the apparatus will be described.
First, there is a method of providing a means for detecting that the remaining amount of toner has run out for each of the developing devices 24a to 24d. In this embodiment, for example, as shown in FIG.
Is used. The piezoelectric element 141 is provided in the developer storage chamber 5
1 is attached to a part of the partition wall 57 between the toner replenishing chamber 53 and the surface thereof is disposed toward the toner replenishing chamber 53. The output voltage level from the piezoelectric element 141 is different when the pressure of the toner is applied to the surface of the piezoelectric element 141 and when the pressure is not applied. Further, at the blade tip of the toner supply auger 66 in the toner supply chamber 53, the surface of the piezoelectric element 141 is periodically rubbed so that the piezoelectric element 141 does not erroneously detect the presence or absence of toner due to toner blocking or the like. A bending member 142 is provided.

Then, as shown in FIG. 11, the piezoelectric element 1
By comparing the signal level from 41 with the reference value in the comparison circuit 143, the presence or absence of the remaining toner amount in the toner replenishing chamber 53 at the position of the piezoelectric element 141 is detected, and if it is detected that there is no remaining toner amount, The main body of the image forming apparatus or the display of a peripheral device communicating with the image forming apparatus is used as the toner cartridge exchange display 144.
A message prompting replacement of the toner cartridge may be displayed.

In this embodiment, the piezoelectric element is used to detect the presence / absence of toner, but a method of optically detecting the presence / absence of toner may be used as the detection method. For example, the light reflecting means is arranged inside each of the developing devices 24a to 24d, and
a to 24d Beam light is incident from the outside through a transparent window provided on the outer wall of the developing device, and the intensity of the reflected light from the light reflecting means is detected, and the light is provided between the light reflecting means and the transparent window. For example, there is a method of blocking the light beam when there is toner. With such optical means,
On the other hand, there is an advantage that the power supply means is not required as in the case of using the piezoelectric element, but on the other hand, in order to maintain good detection accuracy, a member for periodically cleaning the surfaces of the light reflection means and the transparent window is required.

A common feature of the method of providing the means for detecting the remaining amount of toner for each of the developing devices 24a to 24d is that some cost is added to the basic structure, but
There is an advantage that the replacement of the toner cartridge can be surely prompted before the image defect such as the decrease in density is caused.

As another method, the total value for all pixels of the index indicating the density of each pixel, which is used to maintain the development density in this embodiment, is calculated for each color component, and There is also a method of using a counter that counts each image formation. Specifically, as shown in FIGS. 9 and 12, an integrator 151 that integrates the count value for each image formation for each color component after the counters 101 to 104.
To 154, for example, the upper limit counter 155 detects whether or not the integrated value of the integrators 151 to 154 has reached a certain value, and when the integrated value of the integrators 151 to 154 has reached a certain value. , A message prompting the replacement of the toner cartridge is displayed. Even in this method,
The display is displayed on the display unit (toner cartridge replacement display) 156 of the image forming apparatus main body or a peripheral device communicating with the image forming apparatus. With this method, there may be some error between the time when the remaining amount of toner is truly empty and the time when the replacement message is displayed.
Since there is no need for means for detecting the remaining amount of toner for each of the developing devices 24a to 24d, there is an advantage that the cost can be extremely reduced.

Further, as another method, an element (density sensor) 1 for optically reading the amount of toner developed on the electrostatic latent image, which is used for maintaining the development density in this embodiment.
There is also a method of using 31. For example, FIGS.
As shown in FIG. 3, the output of the element 131 for optically reading the toner amount is compared with a reference value in the comparison circuit 161 during a certain image forming process, so that the toner amount developed on the latent image carrier 21 is reduced. An operation of detecting that the toner amount is smaller than the standard developing toner amount and correcting the toner replenishing amount to the toner replenishing means, in other words, even if the toner replenishing process 162 is repeated up to the upper limit value of the upper limit counter 163 a certain number of times, the subsequent image formation is performed. When the amount of developing toner does not rise at all, the toner cartridge replacement display 164
The display prompts the user to replace the toner cartridge. According to this method, it is possible to display a message prompting the replacement of the toner cartridge, and at the same time, the image density starts to decrease, and in a strict sense, the image density cannot be maintained instantaneously. Further, since it is necessary to set the period for reading the toner amount of the latent image carrier 21 to be considerably short, the number of prints per unit time may decrease depending on the relationship between the transfer drum 251 and the size of the image as described above. is there. However, similar to the method using the integrated value of the counter described above, there is no need for means for detecting the remaining amount of toner for each of the developing devices 24a to 24d, so that there is an advantage that the cost can be extremely reduced.

Further, in this embodiment, only the toner storage chamber 52 is constructed as a replaceable cartridge 55. However, as shown in FIG. 14, for example, as shown in FIG.
All of the toner storage chamber 52 and the toner supply chamber 53, that is, the developing devices 24a to 24d themselves may be configured as a replaceable integrated cartridge 170.

[0064]

As described above, according to the present invention, the developer storage chamber for storing the two-component developer and the toner storage chamber for disposing the toner stirring member are provided. A long toner replenishing chamber having a small volume equivalent to at least one toner replenishment amount is provided facing the chamber, and a part of this toner replenishing chamber communicates with the developer accommodating chamber and the toner replenishing is performed. Since the toner supply member for supplying the toner in the toner supply chamber to the developer accommodating chamber is arranged in the chamber, the following basic effects are obtained. That is, it is possible to push the toner in the toner storage chamber to the side of the long toner replenishment chamber having a small volume and perform the toner replenishment operation in this state. Even if the toner in the room moves, the toner replenishing operation can be stably realized. Further, each toner container is provided outside the rotary developing device, and each developing device in the rotary developing device and each toner container are connected by a toner transport mechanism, or on the entire one wall surface of the toner storage chamber. Since it is not necessary to provide a shutter mechanism or the like, it is possible to effectively avoid an increase in inertial mass due to the extremely large size of the rotary developing device, and accordingly, it is possible to realize high-speed switching of the developing device.

Further, in the present invention, if the toner supply member is driven only in the developing device at the developing position to execute the toner replenishment operation from the toner replenishment chamber to the developer accommodating chamber, for example, in the single color mode, a large number of sheets are printed. Even if the developer density is reduced by performing the printing of No. 3, the toner replenishment operation can be performed at the same position without rotating the developing device at the developing position. Therefore, even if you print a large number of sheets in the single color mode, without reducing productivity,
It is possible to always obtain a constant density image.

Further, in the present invention, if the toner agitating member and the toner supplying member are independently driven by different driving sources, the toner agitating operation in the toner storage chamber can be independently performed separately from the toner replenishing operation. it can. In particular,
If the toner agitating member is driven with respect to the developing position and the developing device located at least one position before the developing position, the toner is sufficiently filled in the toner supplying chamber before the toner supplying operation. Therefore, it is possible to perform the preliminary preparation, and the toner replenishing operation can be stably performed correspondingly.

Furthermore, in the present invention, the developer accommodating chamber and the toner replenishing chamber are partitioned by a partition wall having a notch formed in a part thereof, and toner is supplied to the developer in the developer accommodating chamber near the notch. By disposing a rectifying member for preventing backflow into the chamber, it is possible to reliably avoid a situation in which the developer in the developer storage chamber flows back to the toner replenishing chamber side.
It is possible to more reliably suppress the long-term concentration fluctuation of the developer in the developer accommodating chamber.

Further, if there is a sufficient amount of toner in the toner storage chamber to fill the toner supply amount, the toner is filled in the toner supply chamber. Therefore, in the present invention, the toner empty detecting means is provided. By doing so, the residual toner in the toner storage chamber can be detected more accurately.

In the present invention, if the toner storage chamber of the developing device or the developing device itself is a replaceable cartridge, the toner replenishing performance can be immediately improved by a simple operation of replacing the cartridge when the toner for replenishment is exhausted. You can recover.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a rotary developing device according to the present invention.

FIG. 2 is an explanatory diagram showing an embodiment of a color image forming apparatus having a rotary developing device to which the present invention is applied.

FIG. 3 is an explanatory diagram showing details of the rotary developing device according to the embodiment.

FIG. 4 is an explanatory diagram showing details of each developing device of the rotary developing device according to the embodiment.

FIG. 5 is an explanatory diagram showing a toner replenishing mechanism according to the embodiment.

FIG. 6 is a sectional view taken along line VI-VI in FIG.

FIG. 7 is an explanatory diagram showing another modification of the toner supply mechanism.

FIG. 8 is an explanatory diagram showing a drive system of a rotary developing device used in the examples.

FIG. 9 is a schematic configuration diagram showing an example of a toner replenishment control device used in the embodiment.

FIG. 10 is an explanatory diagram illustrating an example of correction processing of the toner replenishment control device used in the embodiment.

FIG. 11 is an explanatory diagram showing an example of a method of displaying the replacement time of the cartridge used in the embodiment.

FIG. 12 is an explanatory diagram showing another modified example of the method for displaying the cartridge replacement time.

FIG. 13 is an explanatory diagram showing still another modified example of the method for displaying the cartridge replacement time.

FIG. 14 is an explanatory diagram showing another configuration example of the developing device of the rotary developing device according to the embodiment.

[Explanation of symbols]

1 ... Rotating housing, 2 (2a-2d) ... Developing device, 3 ...
Developer carrier, 4 ... Developer stirring and conveying member, 5 ... Developer accommodating chamber, 6 ... Toner stirring member, 7 ... Toner storage chamber, 8 ... Toner supply member, 9 ... Toner supply chamber, 10 ... Partition wall, 11 ...
Notch portion, 12 ... Rectifying member, 13 ... Toner empty detection means, 14 ... Latent image carrier

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location G03G 15/01 113 G03G 15/00 554

Claims (8)

[Claims] 1. A plurality of developing devices (2: 2a to 2d) are mounted on a rotary housing (1) which is driven to rotate intermittently by a driving means, and a predetermined developing device (2) is arranged corresponding to a developing position. In the rotary developing device for developing the electrostatic latent image on the latent image carrier (14), each developing device 2 includes a developer carrier (3) and two-component development on the developer carrier (3). A developer accommodating chamber (5) in which a developer agitating / conveying member (4) for agitating and conveying an agent and a toner for replenishment are stored, and a toner agitating member (6) is provided inside.
And a toner storage chamber (7) in which the toner storage chamber (7) is disposed, and a long toner replenishment having a small volume equal to or larger than a toner replenishment amount at least once at a portion facing the toner storage chamber (7). A chamber (9) is provided, and a part of the toner replenishing chamber (9) communicates with the developer accommodating chamber (5). A rotary developing device, characterized in that a toner supply member (8) for replenishing toner to the developer storage chamber (5) is provided. 2. The toner according to claim 1, wherein the toner supply member (8) is driven only in the developing device (2) at the developing position to transfer the toner from the toner replenishing chamber (9) to the developer accommodating chamber (5). A rotary developing device characterized by executing a replenishing operation. 3. The rotary developing device according to claim 1, wherein the toner stirring member (6) and the toner supply member (8) are independently driven by different driving sources. 4. The toner agitating member (6) in the toner storage chamber (7) according to claim 1, wherein the developing position and at least one developing device (2) located before the developing position. A rotary developing device, characterized in that it drives. 5. The partition according to claim 1, wherein the developer accommodating chamber (5) and the toner replenishing chamber (9) are parted by a partition wall (10) having a notch (11). ,
In the vicinity of the notch (11), the developer storage chamber (5)
A rotary developing device, characterized in that a rectifying member (12) is provided for preventing a back flow of the developer in the toner replenishing chamber (9). 6. The rotary developing device according to claim 1, wherein a toner empty detecting means (13) is provided in the toner replenishing chamber (9). 7. The rotary developing device according to claim 1, wherein the toner storage chamber (7) is composed of a replaceable cartridge. 8. The rotary developing device according to claim 1, wherein each of the developing devices (2) is constituted by a replaceable integral cartridge.