JPH1165251A - Developing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably and sufficiently maintain developer electrification capability over a long period of time by supplying carrier or developer whose amount corresponds to an amount of supplied toner, and also discharging used developer. SOLUTION: When a cartridge 5a is replaced with fresh one, a replenishment control means 7 replenishes a development housing 2 with a fixed amount of carrier or developer (an amount matching an mount of toner in the cartridge 5a). On the other hand, a discharge control means 8 carries e.g. by a developer carrying member 4, used developer in a direction opposite to that used for a normal operation, thereby leading the used developer into the position of a developer discharge means 6, and discharging by a developer discharge means 6 the developer whose amount corresponds to that of the newly added carrier or developer. In the case, the timing of the start of the operations of the replenishment control means 7 and discharge control means 8 are set on condition that the cartridge 5a is loaded in a toner/carrier replenishment means 5. This prevents the developer from being supplied insufficiently or excessively and maintains the electrification capability.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a developing device used in an image forming apparatus such as an electrophotographic copying machine or a printer, and more particularly to a developing device for forming a developer layer of a magnetic brush on a developer carrier. The present invention relates to an improvement in a developing device that applies an electric field between a latent image carrier and a developer carrier to develop a latent image on the latent image carrier.

[0002]

2. Description of the Related Art Conventionally, in a developing device of an image forming apparatus using an electrophotographic method, a two-component developer composed of a carrier and a toner is often used. A developing housing having a portion facing the image carrier and having an opening as a developing opening, a developer carrier (developing roll) disposed at a portion facing the developing opening, and a back surface of the developer carrier; On the side, there is generally provided a developer transporting member which transports the newly replenished developer or toner and the developer in the developing housing to the developer carrier while being stirred.

In the above-described developing device, the charging ability of the developer, particularly the carrier, decreases as the use period increases, which causes deterioration of image quality and the like. For this reason, the user or the service person has exchanged the developer in the developing device. However, replacement of the developer is time-consuming and often has poor workability. In order to avoid such a problem, there has been proposed a so-called trickle developing device that supplies not only the toner but also the carrier or the developer and discharges the developer in the developing device. As this type of developing device, for example, as disclosed in Japanese Patent Publication No. 2-21591, there is provided a device in which a developer overflow portion is provided at a predetermined height of a housing side wall to discharge the developer, and Japanese Patent Application Laid-Open No. Sho 53-22747. As disclosed in Japanese Patent Application Laid-Open Publication No. H11-163, an apparatus that supplies a fixed amount of developer, detects a volume change, and controls the developer in the developing housing to have a predetermined volume or a constant developer concentration, or As disclosed in Japanese Unexamined Patent Publication No. Hei 4-66984, a device for controlling the discharge opening so as to replenish the developer and to transport and discharge the deteriorated developer every fixed number of sheets,
As disclosed in JP-A-8781, there is a device that measures the weight of a developing device and controls the charging and discharging of the developer. These apparatuses are preferable in that image defects such as image quality deterioration and background fog due to a decrease in charging ability due to the deterioration of the developer can be avoided without performing a developer replacement operation.

[0004]

However, in an apparatus such as that disclosed in Japanese Patent Publication No. Hei 2-21591, in which only a discharge port is provided at a certain height, the developer which accompanies a rapid change in toner density is used. Susceptible to volume changes. Therefore, when the toner concentration suddenly increases and then decreases, the amount of the developer in the developing device may be insufficient, and the supply amount to the developer carrier may be insufficient. Also, JP-A-53-22747
JP-A-5-188787 and JP-A-5-187871 can avoid the shortage of the supply amount to the developer carrier,
Special detection means and control means for determining the supply and discharge of the developer are required, which leads to an increase in the cost of the developing device. Further, in the type described in Japanese Patent Application Laid-Open No. 4-66984, no special detection means is required because the output of the counter for counting the number of image formation is used. However, depending on the image area ratio to be formed, the charging ability of the developer is reduced more than expected, and the image quality is deteriorated, or the supply of more carriers than necessary increases the running cost.
This indicates that the decrease in the charging ability of the developer is due to the toner component adhering to the carrier. It can be said that it is related to quantity. Therefore, a developing device to which at least a carrier or a developer is supplied and which has a developer discharge portion (a trickle type developing device)
In the above, it is an important technical subject to supply a carrier or a developer in an amount corresponding to an amount of toner to be supplied and to discharge a predetermined amount of the developer with a simple configuration.

SUMMARY OF THE INVENTION The present invention has been made to solve the above technical problems, and has a simple structure without using complicated mechanisms and controls, and can cope with an amount corresponding to the supplied toner. A developing device capable of supplying a predetermined amount of a carrier or a developer and discharging a predetermined amount of the developer, and thereby stably and sufficiently maintaining the charging ability of the developer for a long period of time. is there.

[0006]

That is, according to the present invention, as shown in FIG. 1, a developing opening is provided at a portion facing a latent image carrier 1 on which an electrostatic latent image is formed, and a toner and a carrier are provided. Housing 2 containing a two-component developer composed of
A developer carrying member 3 arranged to face a developing opening of the developing housing 2 and carrying the developer to a developing region facing the latent image carrying member 1; and a developer in the developing housing 2. A developer transport member 4 for supplying developer to the developer carrier 3 by stirring and transporting the toner, and a toner and carrier storage means including a detachable cartridge 5a for storing at least toner. In a developing device provided with a toner carrier replenishing means 5 for replenishing and a developer discharging means 6 discharging the used developer in the developing housing 2 to the outside, the cartridge 5a is mounted on the toner carrier replenishing means 5. Under the above conditions, the supply control means 7 for supplying at least a predetermined amount of carrier from the toner / carrier supply means 5 and the toner / carrier supply means 5 Under the condition that the cartridge 5a is mounted, the used developer in the developing housing 2 is discharged from the developer discharging means 6 in accordance with the amount of the developer containing substantially the same amount of carrier as the carrier supplied by the supply control means 7. And discharge control means 8 for discharging.

In such technical means, as the developer conveying member 4, any one can be used as long as the developer is stirred and conveyed in a predetermined developer circulation path to supply the developer to the developer carrier 3. A spiral auger can be selected as appropriate. In this embodiment, as illustrated in FIG. 1, the developer circulating path is vertically divided by a partition member along the axial direction of the developer carrier 3, and the developer carrier 3 of the partition member May have a two-stage structure in which communication ports are formed at both ends in the axial direction, or may have a two-stage structure parallel to the bottom of the developing housing 2 and front and rear with respect to the developer carrier 3. You may. In particular, in a developer circulation path having a two-stage upper and lower structure, a developer carrier 3 is usually disposed facing the upper part, and the developer is circulated and transported from the lower part toward the upper part. However, the present invention is not limited to this. For example, the developer carrier 3 may be disposed facing the lower portion, and the developer may be circulated and transported from the upper portion to the lower portion.

The supply port from the toner / carrier supply means 5 can be basically provided at an arbitrary position of the developing housing 2 facing the developer circulation path. In consideration of the stirring property with the existing developer, it is preferable to provide the developer circulating passage at one axial end of the developer carrier 3 in the developer circulation path. And
The replenishing port may be configured to replenish the new developer composed of the toner and the carrier from one place, or may be configured to replenish the toner and the carrier separately.

Further, the toner / carrier replenishing means 5 only needs to include a toner and carrier storing means including at least a detachable cartridge 5a for storing the toner, and the storing means comprises one cartridge.
The cartridge may be divided into an area in which the toner is stored and an area in which the developer or carrier including the toner and the carrier is stored, or the cartridge may store the toner or the carrier. And a second storage unit (a cartridge or a fixedly installed storage box or the like) for storing a developer or a carrier comprising a toner and a carrier. Here, in the former mode as the storage means, since a predetermined amount of the developer or carrier may be contained in the cartridge 5a, it is not necessary to perform particularly complicated control. In the latter mode, the predetermined amount of the developer or the carrier may be replenished from the second storage means. Therefore, the replenishment amount of the developer or the carrier per unit time is made constant. By doing so, it is possible to easily perform the replenishing operation only by controlling the time of the replenishing operation.

Further, as the toner carrier replenishing means 5, one or a plurality of supply ports of the storage means and one or a plurality of replenishment ports opened in the developing housing 2 are directly connected. However, from the viewpoint of increasing the degree of freedom in the layout of the toner carrier replenishing means 5, one or more supply ports of the storage means and one or more replenishment ports opened in the developing housing 2 may be used. It is preferable to provide an opening connecting member for communication connection. In this case, in a mode in which the opening connecting member must be somewhat long, it is preferable to incorporate a conveying member for forcibly conveying the toner, the carrier, or the developer in the opening connecting member. Also,
As the developer discharging means 6, a developer discharging port is simply opened in a part of the developing housing 2 as long as a predetermined amount of used developer can be discharged at the time of replenishing operation of the developer or the carrier by the replenishing control means 7. However, from the viewpoint of effectively avoiding the situation where the developer is unnecessarily discharged from the developing housing 2 except when the developer is discharged,
For example, a shutter is provided at the developer outlet, and the developer is discharged according to the opening and closing of the shutter, or a lid member made of a spring material is provided at the developer outlet,
When the pressure of the developer pressing the lid member exceeds a predetermined value,
It is preferable that the lid member is opened to discharge the developer.

The toner and carrier replenishing means 5 and the developer discharging means 6 are provided in the developing housing 2 by the replenishment control means 7 from the viewpoint of effectively utilizing the developer or carrier immediately after replenishment. It is preferable to use a structure in which the developer or the carrier composed of the replenished toner and the carrier is separated from the developer discharged by the developer discharge unit 6 when the discharge control of the developer is performed by the discharge control unit 8. In this type of structure, for example, the replenishing port of the toner / carrier replenishing means 5 and the developer discharging means 6 may be disposed at a position apart from each other. To avoid this, for example, a part of the developer conveying member 4 is provided with a reverse conveying part in which the developer is conveyed in a direction different from the developer circulating direction of the developer circulating path. It is preferable to form a supply port for the developer or the carrier at the location.

The replenishment control means 7 and the discharge control means 8
Starts when the toner / carrier replenishing means 5
The condition is that the cartridge 5a is attached to the cartridge. In this case, the cartridge 5 a
Is detected by a sensor, and a developer or carrier replenishing operation and a developer discharging operation are performed in synchronization with the detection signal, or the cartridge 5a is supplied to the toner / carrier replenishing means 5. When the cartridge is mounted, for example, the supply port of the cartridge 5a is automatically opened, and in conjunction with this, the developer or carrier replenishment operation is performed.
In addition, an appropriate selection may be made, such as a discharge control means for performing a discharge operation of the developer.

Further, as long as the used developer can be discharged by a predetermined amount, the discharging control means 8 can
It is not necessary to switch the developer conveyance direction in particular. However, from the viewpoint of easier operation of discharging the developer, for example, the developer discharging unit 6 is located at a position deviated from the normal developer circulation path. The developer is transported by the developer transport member 4 in a direction opposite to the normal transport direction, and the used developer to be discharged is transported to the developer discharge unit 6. Preferably, it can be drained through.

Further, the operation timing of the supply control means 7 and the discharge control means 8 may be appropriately selected. For example, after the operation of discharging the developer by the discharge control means 8 is completed, the toner and The supply operation of the developer or the carrier composed of the carrier may be set to be started, or the operation of discharging the developer by the discharge control means 8 and the developer or the developer composed of the toner and the carrier by the supply control means 7 may be performed. The carrier supply operation may be started substantially simultaneously. In addition, the amount of the developer discharged by the discharge control means 8 may be unconditionally discharged at a predetermined amount. However, since the deterioration state of the carrier in the developer used differs depending on the environmental information. From the viewpoint of avoiding wasteful discharge of the developer according to the deterioration state of the carrier, the discharge control means 8
It is preferable that a means for determining the amount of used developer discharged based on image forming information before mounting the cartridge 5a at least when the cartridge 5a storing toner is mounted is provided.

Next, the technical means described above will be described. In FIG. 1, when replacing the cartridge 5a, the replenishment control means 7 supplies a fixed amount (an amount corresponding to the amount of toner in the cartridge 5a) of the carrier or the developer to the developing housing 2.
Replenish inside. On the other hand, the discharge control unit 8 guides the used developer to the position of the developer discharge unit 6 by, for example, conveying the used developer by the developer conveying member 4 in a direction opposite to that in the normal operation, and newly supplying the used developer. The amount of the developer corresponding to the carrier or the developer is discharged from the developer discharging means 6.

In such an operation process, the charging ability of the developer is maintained without causing a shortage or an excessive supply of the carrier or the developer regardless of the image area ratio or the like. In addition, since the developer is not discharged when it is not related to the replacement of the cartridge 5a, even if there is a change in the volume of the developer due to the change in the toner concentration, the supply amount to the developer carrier 3 may be insufficient. Absent.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment shown in the accompanying drawings. First Embodiment FIG. 2 shows an example of an image forming apparatus incorporating a developing device according to a first embodiment of the present invention. In the figure, reference numeral 11 denotes a photoconductive photoconductor drum (latent image carrier) having a surface layer made of a negatively charged organic photoconductor on the surface;
Reference numeral 12 denotes a charging device such as a corotron for uniformly charging the photosensitive drum 11 in advance, and 13 denotes a uniformly charged photosensitive drum 11.
An exposure device for irradiating light corresponding to an image thereon to form an electrostatic latent image based on a difference in electrostatic potential; a developing device for visualizing the electrostatic latent image on the photosensitive drum 11 with toner; Reference numeral 15 denotes a transfer device such as a corotron for transferring a toner image formed on the photosensitive drum 11 to a recording material.
This is a cleaning device for cleaning the upper residual toner.

In the present embodiment, the developing device 14
As shown in FIGS. 2 to 4, a portion facing the photosensitive drum 11 has a developing housing 21 that opens as a developing opening 22.
A developing roll (developer carrying member) 23 is provided at a portion facing 2. Here, the developing roller 23 is a fixed non-magnetic developing roller 24 in which a predetermined number of magnetic poles are arranged in a rotatable non-magnetic developing sleeve 24, and carries a two-component developer composed of a toner and a carrier. The electrostatic latent image on the photosensitive drum 11 is developed in a development area corresponding to the development opening 22. Note that a DC superimposed AC voltage, which is a bias voltage, is applied to the developing roll 23 by a high-voltage AC power supply (not shown) and a DC power supply (not shown), and a developing region where the developing roll 23 and the photosensitive drum 11 are close to each other. Thus, an alternating electric field is generated between the electrode under the photosensitive layer on the surface of the photosensitive drum 11 and the grounded electrode. A developer amount regulating member 26 that regulates the amount of the developer on the peripheral surface of the developing roll 23 is provided in the vicinity of the developing roll 23 before reaching the developing area.

The developing roll 2 of the developing housing 21
On the back side of the developing roller 3, upper and lower two-stages are formed which are vertically partitioned by a partition member 27 along the axial direction of the developing roll 23, and formed with communication ports 28 and 29 near both sides of the developing member 23 in the axial direction. A developer circulation path 30 having a structure is formed. In the upper and lower steps of the developer circulation path 30, developer transport members 31, 32 such as augers in which developer transport directions are opposite to each other are provided along the axial direction of the developing roll 23.

Further, in the present embodiment, the upper portion of the developing housing 21 facing the developer circulation path 30 near the upper end is provided with a toner, a carrier or a toner carrier to which the developer is supplied. A supply port 41 is formed.
On the other hand, the developing housing 21 facing the developer circulation path 30
Of the developer outlet 4 for discharging the developer is provided near the communication port 28 in the lower portion on the side close to the toner / carrier supply port 41.
2 are formed. In the present embodiment, a shutter (not shown) is provided at the developer outlet 42 so as to be freely opened and closed. The developer transport members 31 and 32 basically have spiral blades 31a and 32a along the normal developer circulation direction (the direction of the black arrow in FIG. 3).
Spiral blades 31b, 32b extending in the direction opposite to the developer circulation direction are provided at the end of the lower developer transport member 31 near the communication port 29 and the upper developer transport member 32 near the communication port 28, in the normal rotation direction. In this configuration, the developer is guided to the communication ports 28 and 29 so that the developer is effectively prevented from being compressed when passing through the communication ports 28 and 29.

In this embodiment, the toner carrier cartridge 50 shown in FIGS. 4 and 5 is used. The toner carrier cartridge 50 is divided into a hollow cartridge main body 53 by a partition plate 54, so that a toner storage section 51 in which the toner T is stored and a carrier storage section 52 in which the carrier C is stored. The toner storage unit 51 is provided with a toner stirring member 55 for stirring the toner. In the present embodiment, a toner supply port 56 and a carrier supply port 57 are opened in the vicinity of the toner storage section 51 and the carrier storage section 52 of the cartridge main body 53. , 57 are provided with, for example, one shutter 58 so as to be freely opened and closed.

A cylindrical opening connecting member 43 extending upward is provided at the toner carrier supply port 41 of the developing housing 21, and the toner carrier cartridge 50 is mounted on a cartridge receiving portion (not shown). At this time, by rotating the toner carrier cartridge 50 in the direction A in FIG. 5, the shutter 58 is opened, and the supply ports 56 and 57 of the toner carrier cartridge 50 are opened via the opening connecting member 43. 41 is connected.

Further, in this embodiment, as shown in FIG. 4, a cartridge mounting sensor 61 for detecting that the toner carrier cartridge 50 is mounted is provided in a cartridge receiving portion (not shown). Further, a toner density sensor 62 for directly or indirectly detecting the toner density in the developing housing 21 is provided. Here, as the cartridge mounting sensor 61, a limit switch for mechanically detecting that the toner carrier cartridge 50 has reached a predetermined mounting position, an optical sensor for optically detecting, or the like is used. Further, as the toner concentration sensor 62, it is preferable to use an existing concentration sensor for controlling the amount of dispensed toner. For example, a sensor that detects the toner concentration from the magnetic permeability or a sensor that detects the toner concentration from the transmittance is used. In addition to a sensor that detects the output density of a test patch formed on the photoconductor drum 11 and a sensor that detects the latent image potential of the test patch, a sensor that estimates the toner density in the developing housing 21 is also included. It is a thing.

The outputs from the cartridge mounting sensor 61 and the toner density sensor 62 are taken into the control device 63, and the control device 63 executes, for example, a developer discharge amount determining process shown in FIG. ) 31,
The motor controller 64 for driving the motor 32 is controlled.

Next, the operation of the developing device according to the present embodiment will be described. In this embodiment, when the toner concentration sensor 62 detects that the toner concentration is insufficient, a predetermined amount of toner in the toner storage unit 51 is supplied by the toner stirring member 55. At this time, the developer transport member (auger)
Reference numerals 31 and 32 rotate in the normal rotation direction.
As shown in (2), the developer drops from the upper part to the lower part of the developer circulation path through the communication port 28, and is conveyed to the communication port 29 while being stirred and conveyed by the developer conveying member 31 with the developer in the developing housing 21. In this area, the developer that has passed through the developing area is released from the developing roll 23 and is stirred with the developer. Thereafter, the developer transported to the communication port 29 is sent to the upper portion of the developer circulation path, and is transported while being supplied to the developing roll 23 by the developer transporting member 32. Then, the amount of the developer adsorbed on the developing roll 23 is regulated by the developer regulating member 26 and is conveyed to the developing area.

The operation of the developing device according to the present embodiment when the toner carrier cartridge 50 is replaced will be described. When a new toner carrier cartridge 50 is installed, the shutter 58 is opened in the direction B by twisting in the direction A as shown in FIGS. The supply port 57 is opened. At this time, a predetermined amount of the carrier C stored in the carrier storage section 52 is supplied to the toner / carrier supply port 41 of the developing housing 21 via the opening connecting member 43. At this time, when the shutter 58 of the toner / carrier cartridge 50 is opened, the carrier C stored in the carrier storage unit 52 naturally falls by a predetermined amount into the toner / carrier replenishing port 41. No need to do.

The toner carrier cartridge 50
8, the cartridge mounting sensor 61 generates a cartridge mounting signal from the cartridge mounting sensor 61. With this signal, the control device 63 opens a shutter (not shown) of the developer discharge port 42, The developer conveying members (augers) 31 and 32 were rotated for a predetermined time in a direction opposite to the direction of rotation during normal operation. Then, the discharge of the developer is terminated by stopping the reverse rotation of the augers 31 and 32. When the discharge operation of the developer is completed, the developer discharge port 4 is stopped.
The second shutter (not shown) was closed.

Here, the developer conveying member (auger) 3
The reverse rotation times of 1, 32 may be determined in advance,
In the present embodiment, the amount of the carrier present in the developing housing 21 is stably maintained by changing the density according to the toner concentration in the developing housing 21. Generally, as shown in FIG. 6, the reverse rotation time of the augers 31 and 32 and the volume of the discharged developer are substantially linear, and the toner concentration and the weight of the developer per unit volume are also substantially linear. . For this reason, as a process of determining the amount of discharged developer, for example, as shown in FIG.
The weight W0 of the developer per unit volume is predicted from the toner concentration detected in the step (1), and the weight WD of the developer containing substantially the same amount of carrier as the carrier supplied from the carrier storage unit 52 is calculated. The reverse rotation time of the augers 31, 32 is calculated by calculating the volume VD of the developer to be discharged from the auger 31, and for example, by using a timer, the auger 31,
A method of controlling the 32 motor controllers 64 is used. In this embodiment, the carrier C is supplied, but a system for supplying the developer may be used.

Further, a developer conveying member (auger) 31,
During the reverse rotation of the carrier 32, the carrier C supplied into the developing housing 21 from the toner / carrier replenishing port 41 mainly acts on the upper and lower portions of the developer circulation path 30 by the action of the spiral blade 32 b of the developer conveying member 32. Communication port 2 connecting
8, the carrier C newly supplied in the developer circulation path falls from the upper part to the lower part through the communication port 28 and is immediately discharged from the developer discharge port 42. Has been effectively avoided. In addition, toner
The carrier C that has not reached the carrier supply port 41 remains in the opening connecting member 43. Thereafter, the developer transport members (augers) 31 and 32 may be rotated in the normal operation direction to agitate the replenished carrier C and the developer in the developing housing 21. Further, while rotating in the normal operation direction, the toner stirring member 55 of the toner carrier cartridge 50 may be rotated to match the toner concentration before the replacement of the toner carrier cartridge.

When such a carrier replenishment and developer discharging operation is performed, the charging ability of the developer can be stably maintained for a long period of time as shown in Example 1 described later. During the test, no image roughness was observed.

Second Embodiment FIG. 11 shows a developing device according to a second embodiment of the present invention. In the figure, the basic configuration of the developing device according to the present embodiment is substantially the same as that of the first embodiment.
The configurations of the carrier cartridge 50 and the opening connecting member 43 are different from those of the first embodiment. Note that components similar to those of the first embodiment are denoted by the same reference numerals as those of the first embodiment, and detailed description thereof is omitted here. In the present embodiment, the toner / carrier cartridge 5
0 has a toner storage unit 51 for storing the toner T and a carrier storage unit 52 for storing the carrier C, as in the first embodiment, but differs from the first embodiment. As shown in FIG. 12 and FIG.
Stores toner in a cylindrical cartridge main body 53 and arranges a toner stirring member 55 for stirring toner.
A toner supply port 56 is opened on the outer peripheral surface near one end of the cartridge body 53, and the toner supply port 56 is provided to be openable and closable by a shutter 58 (specifically, 58a). Body 5
A hollow ring 71 is removably fitted to a part of the outer peripheral surface of the carrier 3 and a predetermined amount of a carrier C is stored in the hollow ring 71 in advance. 57, and the carrier supply port 57 is provided so as to be openable and closable by a shutter 58 (specifically, 58b). That is, in the present embodiment, the toner carrier cartridge 50 employs a configuration in which the toner storage unit 51 and the carrier storage unit 52 are formed as separate members and used integrally.

In the present embodiment, the toner carrier cartridge 50 is mounted on the cartridge holding member (cartridge receiving portion) 72 as in the first embodiment. Since the positional relationship between the carrier supply port 57 and the toner / carrier supply port 41 of the developing housing 21 is set apart,
Supply ports 56 and 5 of toner carrier cartridge 50
A long two opening connecting members 43 (specifically, 43a and 43b) are connected between the opening 7 and the toner / carrier replenishing port 41. Each opening connecting member 43 includes, for example, an auger. A toner transport member 73 and a carrier transport member 74 are provided.

In this embodiment, an operation process when replacing the toner carrier cartridge 50 will be described. As shown in FIGS. 11 to 13, when the toner carrier cartridge 50 is mounted on the cartridge holding member 72, the toner carrier 51 is twisted in a predetermined direction, so that the toner storage unit 51 is rotated.
And shutter 5 attached to carrier storage 52
8 (58a, 58b) is opened, and the toner supply port 56 and the carrier supply port 57 are opened. At this time, the carrier C stored in the carrier storage unit 52 is
Drops naturally during b. Then, as shown in FIG. 14, when the carrier / toner cartridge 50 is mounted, a cartridge mounting signal is generated from the cartridge mounting sensor 61, and the control device 63 uses this signal to cause the shutter (not shown) of the developer outlet 42. ) Is released, and the developer conveying members 31 and 32 are rotated for a predetermined time in a direction opposite to the direction of rotation during normal operation. Then, the discharge of the developer is terminated by stopping the reverse rotation of the developer conveying members 31 and 32, and the shutter (not shown) of the developer discharge port 42 is closed. Here, the reverse rotation time of the developer conveying members 31 and 32 may be determined in advance, but is determined based on the toner concentration of the developer in the developing housing 21 as in the method described in the first embodiment. Is also good.

Thereafter, as shown in FIG. 14, the carrier transport member 74 is moved for a predetermined time by a timer, for example.
Is rotated, and the developer transport members 31 and 32 are rotated in the normal operation direction.
And the supply carrier C and the developing housing 21
Stir with the developer inside. At this time, the carrier transport member 7
The rotation time of the developer carrier 4 and the developer transport members 31 and 32 may be such that a predetermined carrier (for example, 100 g) is supplied into the developing housing 21 and stirring is sufficiently performed.

Third Embodiment FIG. 15 shows a developing device according to a third embodiment of the present invention. In the figure, the basic configuration of the developing device according to the present embodiment is substantially the same as that of the first embodiment, but unlike the first embodiment, only the toner T is stored in the toner cartridge 81, and the carrier C is the carrier. It is supplied from a dispenser 82. In the present embodiment, the toner cartridge 81 is configured to be mounted on a cartridge holding member (cartridge receiving portion) 72, and stores toner in the cylindrical cartridge main body 53, as well as toner stirring for toner stirring. A member 55 is provided, a toner supply port 56 is opened on the outer peripheral surface near one end of the cartridge main body 53, and the toner supply port 56 is opened and closed by a shutter 58. An opening connecting member 43a and a toner conveying member 7 are provided between the developing housing 21 and the toner / carrier replenishing port 41.
3 through a communication connection. On the other hand, the carrier dispenser 82 has a carrier replenishing member 83 provided at the carrier supply port portion, and the carrier supply port and the developing housing 2 are provided.
The first and carrier supply ports 41 are connected to each other via an opening connecting member 43b and a carrier conveying member 74.

Next, the operation of the developing device according to this embodiment when the toner cartridge 81 is replaced will be described. Now, when the toner cartridge 81 is mounted on the cartridge holding member 72, the toner cartridge 81 is twisted in a predetermined direction,
The shutter 58 is opened, and the toner supply port 56 is opened. When the toner cartridge 81 is mounted, a cartridge mounting signal is generated from the cartridge mounting sensor 61, and the control device 63 opens a shutter (not shown) of the developer discharge port 42 by this signal as shown in FIG. Then, the developer conveying members 31 and 32 are rotated for a predetermined time in a direction opposite to the rotation direction in the normal operation. Then, the discharge of the developer is terminated by stopping the reverse rotation of the developer conveying members 31 and 32, and the shutter (not shown) of the developer discharge port 42 is closed. Here, the reverse rotation time of the developer conveying members 31 and 32 (defined by the timer 1) may be determined in advance, but the developing time in the developing housing 21 is similar to the method described in the first embodiment. It may be determined according to the toner concentration of the agent.

Thereafter, as shown in FIG. 16, the control device 63 drives the carrier replenishing member 83 for a predetermined time (defined by, for example, the timer 2), and the predetermined amount (10
0g) is supplied to the opening connecting member 43b and stopped. The carrier transport member 74 is driven for a predetermined time (defined by the timer 3) to transport and replenish the carrier C into the developing housing 21. Further, the carrier transport member 74 is rotated and the developer transport member 3 is rotated.
1, 32 in the normal operation direction, and the developing housing 2
1 and the developing housing 21
Stir with the developer inside. Here, the carrier transport member 74
A predetermined carrier (100 g) may be supplied to the inside of the developing housing 21 for the rotation time of the developer conveying members 31 and 32, and sufficient stirring may be performed.

Fourth Embodiment FIG. 17 is an explanatory view showing a developing device according to a fourth embodiment of the present invention. In the present embodiment, the basic configuration of the developing device is substantially the same as that of the third embodiment, but different from the third embodiment, while the toner T is supplied from the toner cartridge 81, and the carrier C is the carrier dispenser 82. , And is supplied from a carrier cartridge 85. In the present embodiment, the toner cartridge 81 is mounted on a first cartridge holding member (cartridge receiving portion) 91, and a toner stirring member (not shown) stirs and conveys the toner inside, and a toner supply port 56. Is opened and closed by a shutter (not shown), and an opening connecting member 43 is provided between the toner supply port 56 and the toner carrier supply port 41 of the developing housing 21.
a and the toner conveying member 73. On the other hand, the carrier cartridge 85 is mounted on a second cartridge holding member (cartridge receiving portion) 92, agitates and transports the internal carrier by a carrier transporting member (not shown), and closes the carrier supply port 57 with a shutter (see FIG. The carrier supply port 57 and the toner / carrier supply port 41 of the developing housing 21 are communicatively connected via the opening connecting member 43b and the carrier conveying member 74. .

Next, the operation of the developing device according to the present embodiment when the toner cartridge 81 is replaced will be described. Now, when the toner cartridge 81 is mounted, a cartridge mounting signal is generated from the cartridge mounting sensor 61, and the control device 63 sends the developer mounting port 4 by this signal.
The shutter (not shown) of No. 2 is opened, and the developer conveying members 31 and 32 are rotated in a direction opposite to the rotation direction in the normal operation.
2 is stopped by stopping the reverse rotation of
Shutter (not shown) was closed. The reverse rotation time of the developer conveying members 31 and 32 may be determined in advance, but may be determined based on the toner concentration of the developer in the developing housing 21 as in the method described in the first embodiment. Good.

Thereafter, the control device 63 drives the carrier stirring member (not shown) in the carrier cartridge 85 for a predetermined time to supply a predetermined amount (100 g) of the carrier to the opening connecting member 43b. Stop. Further, the carrier C is supplied into the developing housing 21 by driving the carrier conveying member 74. Further, the carrier transport member 74
Is rotated, and the developer transport members 31 and 32 are rotated in the normal operation direction.
And stirred with the developer in the developing housing 21. Carrier transport member 74 and developer transport members 31, 3
For the rotation time of 2, the predetermined carrier (100 g) may be supplied into the developing housing 21 and stirring may be sufficiently performed.

In this embodiment, for example, the discharge of the developer in the developing housing 21 and the replenishment of the carrier are performed at different timings. However, the timing is not limited to this. For example, when the toner amount in the toner cartridge 81 is small and the amount of the carrier to be replenished is small, or when the carrier is close to the opening connecting member 43 b and the toner carrier replenishing port 41 of the developing housing 21. If there is enough space to hold the developer, the developer discharge and the carrier supply may be performed substantially simultaneously. However, in this case, it is preferable that the carrier is supplied to a position where the carrier is conveyed in a direction opposite to the communication port 28 connecting the upper part and the lower part of the developer circulation path. In the present embodiment, the carrier is supplied every time the toner cartridge 81 is replaced. However, the number of replacements of the toner cartridge 81 is counted, and the required amount of the carrier is supplied once at the determined replacement number. You may.

In each of the embodiments described above, a developing device applied to a single-color image forming apparatus has been described. However, the present invention is not limited to this. For example, as shown in FIG. A plurality of image forming units 100 (specifically, 100K, 100Y, 100M, and 100C) are arranged in parallel for each of black, yellow, magenta, and cyan. , A charging device 12, an exposure device 13, a developing device 14, a transfer device 15, and a cleaning device 16, and the square color component toner images formed by the respective image forming units 100 are sequentially superimposed on the paper 17 and transferred onto the transfer paper and the fixing device 18. The embodiments described in each of the embodiments may be applied to the developing device 14 of the multicolor image forming apparatus in which the desired toner image is fixed on the paper 17. It is a matter of course.

[0043]

【Example】

Example 1 The performance was confirmed using the developing device 14 described in the first embodiment. The main configuration and developing conditions of the developing device 14 are as follows. Developing roll 23: Outer diameter 30mm: Sleeve 24 rotation speed 455mm / sec Augers 31, 32: Outer diameter 23.5mm (both upper and lower stages): Number of rotations 446rpm (both upper and lower stages) Distance between photosensitive drum 11 and developing roll 23: 0.4 mm Photoconductor drum 11 rotation speed: 260 mm / sec Toner image forming section potential: -300 V Background section potential: -700 V Development bias (DC): -550 V Development bias (AC, peak to peak): 1.5 kV Development bias (AC, Duty): 0.5 Development bias (AC, frequency): 4.0 kHz

The developer comprises a ferrite carrier having an average particle size of 35 μm and a toner having an average particle size of 7 μm. The developer in the developing device is 900 g at a toner concentration of 6.0% by weight.
Met. Further, in the toner carrier cartridge 50 shown in FIG. 5, the toner storage unit 51 stores 500 g of toner, and the carrier storage unit 52 stores 100 g of carrier.

In such a developing device, when a new toner / carrier cartridge 50 was mounted, the carrier was replenished and the developer was discharged. In this embodiment, for example, the toner concentration is 6.0% by weight.
, The reverse rotation time of the augers 31 and 32 is about 4 seconds,
The discharged developer was about 109 g. In this embodiment, a toner image is formed on the latent image carrier (photosensitive drum) 11 at an image area ratio of 15% and 3%, and a substantially constant amount (4.5 g / m ² ) of toner is formed on paper. A running test was performed while supplying toner so that the toner was transferred.
The results required that the toner carrier cartridge 50 needs to be replaced about every 5,000 sheets when the image area ratio is 15% and about every 1,000 sheets when the image area ratio is 3%. FIG. 9 shows the relationship between the number of running sheets (JIS 4 size paper) and the charging ability AT of the developer.

Further, the toner concentration TC, the charge amount of the toner,
The relationship with the so-called Tribo reciprocal is empirically shown in FIG.
And the degree of deterioration of the developer is the same, the change rate a of the reciprocal of Tribo with respect to the toner concentration TC is substantially constant. However, when the deterioration of the developer progresses and the charging ability decreases, T.sub.
It is also known that the rate of change a of the reciprocal of ribo increases. For example, in the case of FIG. 10, as the deterioration of the developer progresses, the change rate changes from a1 to a2, and further to a3.

Here, the relationship between the toner concentration TC and the charge amount (Tribo) of the toner is given by the following equation (1), and the reciprocal of the change rate a related to the deterioration of the developer indicates the charging ability. it is conceivable that. Further, the reciprocal of the change rate a is assumed to be obtained by the following formula 2 as the charging ability AT (the smaller the AT, the lower the charging ability) in FIG. 1 / Tribo = a × (TC + k) (Equation 1) where, Tribo is the amount of charge per unit weight of toner, TC is the toner concentration, k is a constant depending on the particle size and type of toner and carrier, and It is the change rate of 1 / Tribo. AT = 1 / a = Tribo × (TC + k) (Expression 2) where, AT: Charging capacity of developer Tribo: Charge amount per unit weight of toner, TC: Toner concentration, k: Particle size of toner and carrier And a constant depending on the type, and a is a change rate of 1 / Tribo with respect to TC.

As shown in the results, the charging ability of the developer could be kept stable for a long time. Also,
During the running test (the number of running), no image roughness was observed. In this embodiment, 100 g of the carrier is supplied to 500 g of the toner, but this ratio may be changed depending on the developer or the value of the charging ability AT to be stabilized.

Comparative Example Under the same conditions as in Example 1, a running test was performed by replenishing only the toner from the toner carrier cartridge 50. The result is shown in FIG. According to the figure, unlike the case of the first embodiment, it was found that the charging ability AT did not decrease gradually even when the number of sheets exceeded about 20,000 sheets, and continued to decrease. Also, the roughness of the image is
At an image area ratio of 15%, the image is remarkably seen from around 30,000 sheets, and at an image area ratio of 3%, from around 40,000 images. Further, when the image area ratio is 15%, 50,0
The running test was discontinued because fog on the blank section became noticeable at around 00 sheets.

Examples 2 to 4 The same running test was performed on each of the developing devices of the embodiments 2 to 4 under the same configuration and developing conditions as those of Example 1, respectively. Results were obtained.
In the second to fourth embodiments, as in the first embodiment, for example, when the toner concentration is 6.0% by weight,
The reverse rotation time of 1,32 was about 4 seconds, and the discharged developer was about 109 g.

[0051]

As described above, according to the present invention,
When a cartridge containing at least a toner is mounted on the developing device, a predetermined amount of carrier or a developer composed of toner and carrier is replenished, and the amount of carrier or developer replenished with the developer inside the developing device is supplied. Since the discharge amount is almost the same as the discharge amount, it is possible to maintain the charging ability of the developer stably and sufficiently for a long period of time without using a complicated mechanism or control. Fogging of the background portion can be reliably avoided.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a developing device to which the present invention is applied.

FIG. 2 is an explanatory diagram illustrating an image forming apparatus in which the developing device according to the first embodiment is incorporated.

FIG. 3 is a view as viewed from the direction of arrows in FIG. 2;

FIG. 4 is an explanatory diagram showing a connection example between a toner carrier cartridge and a developing device used in the first embodiment.

FIG. 5A is a perspective view of the toner carrier cartridge according to the first embodiment, and FIG. 5B is a cross-sectional view thereof.

FIG. 6 is a graph showing the relationship between the auger reverse rotation time and the volume of discharged developer in the first embodiment.

FIG. 7 is a flowchart illustrating a developer discharge amount determination process used in the first embodiment;

FIG. 8 is a timing chart showing an operation example when the toner carrier cartridge is replaced in the developing device according to the first embodiment.

FIG. 9 is a graph showing the relationship between the number of prints and developer charging ability in Example 1 and Comparative Example.

FIG. 10 is a graph showing the relationship between toner density and 1 / Tribo.

FIG. 11 is an explanatory diagram illustrating a developing device according to a second embodiment.

FIG. 12 is a perspective view of a toner carrier cartridge used in the second embodiment.

13A is a cross-sectional view of a toner carrier cartridge used in Embodiment 2, and FIG. 13B is an explanatory diagram illustrating a state before a carrier storage unit is incorporated in the toner carrier cartridge.

FIG. 14 is a timing chart showing an operation example when a toner carrier cartridge is replaced in the developing device according to the second embodiment.

FIG. 15 is an explanatory diagram showing a developing device according to a third embodiment.

FIG. 16 is a timing chart showing an operation example when the toner cartridge of the developing device according to the third embodiment is replaced.

FIG. 17 is an explanatory diagram illustrating a developing device according to a fourth embodiment.

FIG. 18 is an explanatory diagram illustrating an example of a full-color image forming apparatus to which the present invention can be applied.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Latent image carrier, 2 ... Developing housing, 3 ... Developer carrier, 4 ... Developer conveying member, 5 ... Toner carrier replenishing means, 5a ... Cartridge, 6 ... Developer discharging means, 7 ... Replenishing control means , 8: discharge control means 11: photosensitive drum,
14 developing device, 23 developing roll, 24 developing sleeve, 25 magnet roll, 26 developer amount regulating member, 27
.., Partition members, 28, 29 ... communication ports, 30 ... developer circulation path, 31, 32 ... developer transfer members (augers), 41 ...
Toner carrier supply port, 42 ... developer discharge port, 43,
43a, 43b opening connection member, 50 toner carrier cartridge, 51 toner storage section, 52 carrier storage section, 56 toner supply port, 57 carrier supply port,
58: shutter, 61: cartridge mounting sensor, 6
2 toner concentration sensor 63 control device 81 toner cartridge 82 carrier dispenser 85 carrier cartridge T toner C carrier

Claims (9)

[Claims] A developing housing having a developing opening at a portion facing a latent image carrier on which an electrostatic latent image is formed and containing a two-component developer composed of a toner and a carrier; A developer carrying member disposed to face the developing opening and carrying and transporting the developer to a developing area opposed to the latent image carrying member; and a developer carrying member which stirs and transports the developer in the developing housing to the developer carrying member. A developer conveying member for supplying the developer,
A toner and carrier replenishing means for replenishing toner and carrier, comprising toner and carrier storing means including a removable cartridge for storing at least toner;
A developer discharging means for discharging the used developer in the developing housing to the outside, wherein at least the carrier is supplied from the toner carrier replenishing means under the condition that the cartridge is mounted on the toner carrier replenishing means. A supply control unit for replenishing a predetermined amount of toner, and a developer amount including substantially the same amount of carrier as the carrier replenished by the replenishment control unit under the condition that the cartridge is mounted on the toner / carrier replenishment unit. A discharge control means for discharging the used developer in the developing housing from the developer discharge means. 2. The developing device according to claim 1, wherein the storing means of the toner / carrier replenishing means comprises a single cartridge, and the cartridge includes a toner storing area and a developer or carrier comprising a toner and a carrier. Characterized by being divided into a storage area and a storage area. 3. The developing device according to claim 1, wherein the storing means of the toner and carrier replenishing means stores first storing means comprising a cartridge for storing toner, and developer or carrier comprising toner and carrier. And a second storage means. 4. The developing device according to claim 1, wherein the toner / carrier replenishing means communicates one or a plurality of supply ports of the storage means with one or a plurality of replenishment ports opened in the developing housing. A developing device comprising a connecting member. 5. The developing device according to claim 1, wherein the developer or the carrier composed of the toner and the carrier replenished into the developing housing by the replenishment control unit is used when the discharge control unit controls the discharge of the developer. A structure that is separated from the developer discharged by the developing device. 6. The developing device according to claim 1, wherein the discharge control means sets a direction in which the developer is conveyed by the developer conveying member in a direction opposite to a normal conveying direction, and controls the used developer to be discharged. A developing device, wherein the developer is conveyed to a developer discharging unit and can be discharged through the developer discharging unit. 7. The developing device according to claim 1, wherein after the discharging operation of the developer by the discharging control unit is completed,
A developing device, wherein a supply operation of a developer or a carrier comprising a toner and a carrier by a supply control unit is started. 8. The developing device according to claim 1, wherein the operation of discharging the developer by the discharge control means and the operation of replenishing the developer or carrier composed of toner and carrier by the supply control means are started substantially simultaneously. Characteristic developing device. 9. The developing device according to claim 1, wherein the discharge control unit discharges the used developer based on image forming information before mounting the cartridge at least when mounting a cartridge storing toner. A developing device comprising means for determining