JP4985014B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus.

A conventional image forming apparatus using a rotary developing device is widely known (see, for example, Patent Documents 1 to 4).
Patent Document 1 discloses a developer in a developing device when a rotating holder rotates with respect to a two-component developing device having a pair of developer circulating conveyance augers in a rotating developing device having a plurality of developing devices mounted on a rotating holder. What provided the baffle plate which prevents the bias | inclination of this is disclosed.
Patent Document 2 discloses a mode in which an idle rotation operation of the developing roll is performed every time the developing device is switched in the rotary developing device.
Further, Patent Document 3 discloses a mode in which the area near the discharge port is set larger than the other areas with respect to the cross-sectional area of the developer stirring chamber.
Furthermore, Patent Document 4 discloses a mode in which fresh toner is not replenished from the toner replenishment path to the developing device even when the developing device exchanger is rotated to replace the developing device set at the developing position. Has been.

Japanese Patent Laid-Open No. 11-65217 (Embodiment of the Invention, FIG. 3) JP 2004-126094 A (Embodiment of the Invention, FIG. 3) JP 2004-333684 A (Embodiment of the Invention, FIGS. 2 to 5) Japanese Patent No. 3552429 (Embodiments of the Invention, FIGS. 2 and 8)

  The technical problem of the present invention is that when the rotary holder rotates by a predetermined amount in a state where the low-use developer exists in the rotary developing device, the stored developer is disturbed in the low-use developer (developer distribution). It is intended to improve the occurrence of a developing operation failure due to bias or a reverse flow of the developer to the developer supply path.

  The invention according to claim 1 is capable of rotating in one direction so as to visualize the electrostatic latent image held on the image holding body and the electrostatic latent image held on the image holding body in a single color or a composite color. A plurality of developing units are mounted on a rotating holder, and each developing unit stops rotating at a developing position and a standby position other than the developing position, and the developing unit can be developed while the developing unit stops rotating at the developing position. An image forming apparatus comprising a rotary developing device that is driven by a motor and a development control device that controls the rotary developing device, wherein each developing device of the rotary developing device includes two components including toner and a carrier. A developer container containing a developer and having a developer circulation path through which the developer circulates; a developer holding body disposed facing the development opening of the developer container; Of the developer circulation path of the developer container, A plurality of agitation and conveyance members that agitate and convey the developer along the developer circulation path by rotating and rotating along the rotation axis direction, and the development control device includes a rotation amount of the rotation holder A rotation amount measuring means for measuring the development amount, a developing drive amount measuring means for measuring a drive amount associated with the developing operation of each developing device, and a predetermined period according to the rotation amount of the rotating holder measured by the rotation amount measuring means. When there is a low-use developer that has a drive amount associated with the developing operation measured by the developing drive amount measuring means that is less than or equal to a predetermined value, the deviation of the developer distribution at the site corresponding to the agitating and conveying member is leveled And an idling drive control means for idling the low-use developer for a predetermined time.

According to a second aspect of the present invention, in the image forming apparatus according to the first aspect, the idle driving control unit assumes a situation in which a poor image quality is observed due to a deviation in developer distribution in a portion corresponding to the stirring and conveying member. The image forming apparatus is characterized in that a predetermined amount is set in advance with respect to the rotation amount of the rotating holder that reaches the condition where the low-use developing device exists .
According to a third aspect of the present invention, in the image forming apparatus according to the first aspect, the idle driving control unit continuously performs a specific single color job using a specific single color image continuously after a predetermined number of times and uses a composite color using all color components. According to another aspect of the present invention, there is provided an image forming apparatus characterized in that a specified number of continuous times of a specific single color job in a state in which density unevenness is seen in a formed image when a composite color job using an image is executed.
According to a fourth aspect of the present invention, in the image forming apparatus according to the first aspect, the idle driving control unit causes the low-use developing device to idle drive after the completion of the image forming job. .
According to a fifth aspect of the present invention, in the image forming apparatus according to the first aspect, the idle driving control unit is a low-use developing device in which a driving amount associated with a developing operation measured by the developing driving amount measuring unit is equal to or less than a predetermined value. The composite color job using all the color components is executed for the low-use developing device under the condition that the rotation amount of the rotation holder by the rotation amount measuring means does not reach a predetermined amount. In this case, the count value of the rotation amount measuring means is returned to 0.

The invention according to claim 6 is capable of rotating in one direction so that the image holding body holding the electrostatic latent image and the electrostatic latent image held on the image holding body are visualized in a single color or a composite color. A plurality of developing units are mounted on a rotating holder, and each developing unit stops rotating at a developing position and a standby position other than the developing position, and the developing unit can be developed while the developing unit stops rotating at the developing position. An image forming apparatus comprising a rotary developing device that is driven by a motor and a development control device that controls the rotary developing device, wherein each developing device of the rotary developing device includes two components including toner and a carrier. A developer container containing a developer and having a developer circulation path through which the developer circulates; a developer holding body disposed facing the development opening of the developer container; Of the developer circulation path of the developer container, A plurality of agitating and conveying members that agitate and convey the developer along the developer circulation path by rotating and rotating along the rotation axis direction, and a new developer replenished in a part of the developer container A developer replenishing port, and the development control device measures the amount of rotation of the rotating holder, and the development drive amount measurement unit measures the drive amount associated with the developing operation of each developing device. A predetermined amount of rotation of the rotating holder by the rotation amount measuring means while there is a low-use developing device in which the driving amount associated with the developing operation measured by the developing drive amount measuring means is not more than a predetermined value. An idle drive control means for idly driving the low-use developer for a predetermined time so as to equalize the deviation of the developer distribution at the site corresponding to the agitating and conveying member under the condition of reaching the quantity. The image forming apparatus.
The invention according to claim 7 is capable of rotating in one direction so as to visualize the electrostatic latent image held on the image holding body and the electrostatic latent image held on the image holding body in a single color or a composite color. A plurality of developing units are mounted on a rotating holder, and each developing unit stops rotating at a developing position and a standby position other than the developing position, and the developing unit can be developed while the developing unit stops rotating at the developing position. An image forming apparatus comprising a rotary developing device that is driven by a motor and a development control device that controls the rotary developing device, wherein each developing device of the rotary developing device includes two components including toner and a carrier. A developer container containing a developer and having a developer circulation path through which the developer circulates; a developer holding body disposed facing the development opening of the developer container; Of the developer circulation path of the developer container, A plurality of agitating / conveying members that agitate and convey the developer along the developer circulation path by rotating and rotating along the rotation axis direction, and excess developer can be discharged by being provided in a part of the developing container. A developer discharge port, and the development control device measures the rotation amount of the rotation holder, and the development drive amount measurement unit measures the drive amount associated with the developing operation of each developing device. The rotation amount of the rotation holder measured by the rotation amount measuring unit is defined in advance while there is a low-use developing device in which the drive amount associated with the developing operation measured by the development drive amount measuring unit is not more than a predetermined value. And an idle drive control means for idly driving the low-use developer for a predetermined time so as to equalize the deviation of the developer distribution in the vicinity of the developer discharge port. Device.
According to an eighth aspect of the present invention, in the image forming apparatus according to the seventh aspect, the idle drive control unit causes the developer discharge operation to be performed from the developer discharge port due to a deviation in the developer distribution near the developer discharge port. An image forming apparatus characterized in that a prescribed amount is set assuming a situation immediately before a defect occurs.

According to a ninth aspect of the present invention, in the image forming apparatus according to any one of the first, sixth, and seventh aspects, the developer holding member further extends along a rotation axis direction of the developer holder, and the developer circulation path of the developer container. disposed in the developer supply path connected partially through the delivery opening, provided with a developer carrying member the developer is driven conveyed toward the delivery opening by rotating the developing control apparatus further , A replenishment drive amount measuring means for measuring a drive amount associated with the developer replenishment operation by the developer conveying member, and a drive amount associated with the developer replenishment operation measured by the replenishment drive amount measurement means is less than a predetermined value. The reverse flow of the developer in the developer replenishment path is restored under the condition that the rotation amount of the rotation holding member by the rotation amount measuring unit reaches a predetermined amount while the developing device is used. Developer transport member for low-use developer An image forming apparatus, characterized in that it comprises a empty drive control means for a predetermined time sky drive against.
According to a tenth aspect of the present invention, in the image forming apparatus according to any one of the first, sixth, and seventh aspects, the developer holding path further extends along a rotation axis direction of the developer holder and the developer circulation path of the developer container. A developer replenishment path connected to a part of the developer supply path through a delivery port is provided, and a developer transport member that rotates and drives the developer toward the delivery port is disposed in the developer supply path. And a developer replenishment mechanism that allows the developer in the developer replenishment path to flow backward in a direction away from the delivery port as the rotation holding member rotates when the rotation of the developer conveying member is stopped . The replenishment drive amount measuring means for measuring the drive amount associated with the developer replenishment operation by the developer transport member of the developer replenishment mechanism, and the drive amount associated with the developer replenishment operation measured by the replenishment drive amount measurement means is predetermined. Low-use development that is The low-use development is performed so that the reverse flow of the developer in the developer replenishing path is restored under the condition that the rotation amount of the rotation holding body by the rotation amount measuring unit reaches a predetermined specified amount in the presence of An image forming apparatus comprising: an idling drive control unit that idly drives the developer replenishing mechanism for a predetermined time.

According to an eleventh aspect of the present invention, in the image forming apparatus according to any one of the first, sixth, seventh, ninth, or tenth aspects, the development control device controls the toner density by directly or indirectly detecting the toner density. An image forming apparatus comprising: a density control unit; and a prohibiting unit for prohibiting a toner density control operation by the density control unit for the developing unit during idle driving by the idle driving control unit. .
According to a twelfth aspect of the present invention, in the image forming apparatus according to any one of the first, sixth, seventh, ninth and tenth aspects, the development control device controls the toner density by directly or indirectly detecting the toner density. An image forming apparatus comprising: a density control unit; and a permitting unit that permits a toner density control operation by the density control unit to the developing unit after the idle driving by the idle drive control unit is completed.

According to the first aspect of the present invention, it is possible to effectively improve image quality defects such as image density unevenness caused by developer disturbance caused by a plurality of rotations of a low-use developer.
According to the second aspect of the present invention, it is possible to effectively avoid image quality defects that hinder development operations.
According to the third aspect of the present invention, it is possible to effectively avoid image quality defects when switching from a specific single color job to a composite color job.
According to the fourth aspect of the present invention, it is possible to effectively improve the disturbance of the developer of the low-use developer without causing any trouble in the image forming job.
According to the fifth aspect of the present invention, when an image forming job capable of improving the disturbance of the developer of the low-use developer is performed, the idle drive control unit is once reset, and subsequently the low-use developer is supplied to the low-use developer. The idle drive control can be started.

According to the sixth aspect of the present invention, image quality defects such as image density unevenness caused by developer disturbance due to multiple rotations of a low-use developer are effective even in an aspect including a developer with developer replenishment. Can be improved.
According to the seventh aspect of the invention, it is possible to effectively improve the developer discharge malfunction (one of the development malfunctions) caused by the developer disturbance caused by the multiple rotations of the low-use developer.
According to the eighth aspect of the present invention, it is possible to effectively avoid the developer discharge failure caused by the multiple rotations of the low-use developer that impedes the developing operation.
According to the ninth aspect of the present invention, even in a mode including a developing device that replenishes the developer from the developer replenishment path, the developer disturbance (to the developer replenishing path) due to multiple rotations of the low-use developer. It is possible to effectively improve the developer replenishment operation failure (one of the development operation failures) caused by the developer backflow).
According to the tenth aspect of the present invention, even when the developer having the developer replenishing mechanism is provided, the developer is disturbed due to a plurality of rotations of the low-use developer (the developer is supplied to the developer replenishment path). It is possible to effectively improve the developer replenishment operation failure (one of the development operation failures) due to (backflow).
According to the eleventh aspect of the present invention, it is possible to eliminate inaccurate density control accompanying density control during idle driving by the idle driving control means.
According to the twelfth aspect of the present invention, accurate density control can be performed in a state where the disturbance of the developer and toner in the developing device is improved.

First, an outline of an embodiment model of an image forming apparatus to which the present invention is applied will be described.
Outline of Embodiment Model FIG. 1A shows an outline of an embodiment model of an image forming apparatus.
In the same figure, the image forming apparatus is unidirectional so as to visualize the electrostatic latent image held by the image holding body 1 holding the electrostatic latent image and the electrostatic latent image held in the image holding body 1 in a single color or a composite color. rotation mounted a plurality of developing devices 3 (3 a to 3 d) to the rotary support 4 possible rotation stop at each of the developing devices 3 are developing position _{P 1} and the developing position _{P 1} other than the standby position _P 2 to P ₄ of the while, with the developing device 3 the developing device 3 is a rotary developing device 2 for driving the developable in a stopped state rotated to the developing position P _1, and a developing control unit 20 for controlling the rotary developing device 2 It is a thing.
In this type of rotary developing device 2, when no image forming job is performed, the developing devices 3 are initially placed on standby at an initial standby position P ₀ so that all the developing devices 3 do not face the development position P _1. Therefore, in many cases, care is taken to prevent the toner and the carrier from flowing out to the image carrier 1 and to prevent the developer from being accumulated, and to maintain the developing performance of each developing device 3 in good condition.

In the present embodiment model, as shown in FIG. 1B, each developing device 3 (3a to 3d) of the rotary developing device 2 contains a two-component developer containing toner and carrier, and a developer. A developer container 5 having a developer circulation path 5a through which the developer circulates, a developer holder 6 that faces the development opening of the developer container 5 and holds and rotates the developer, and the developer container 5 A plurality of agitation transport members 7 (agitating and conveying the developer along the developer circulation path 5a by extending and rotating along the rotation axis direction of the developer holder 6 in the developer circulation path 5a). For example, 7a, 7b).
Here, as a typical aspect of the agitating and conveying member 7, an aspect in which a spiral blade is provided around a normal rotating shaft body is exemplified, but the present invention is not limited thereto. For example, a large number of blade members are provided on the rotating shaft body. May be appropriately selected to be inclined.
In such a developing device 3, a developer replenishing mechanism and a developer discharging mechanism may be added as will be described later.

In such a rotary developing device 2, as shown in FIGS. 2A and 2B, assuming a case where a specific single color job (for example, a single color black job) is continuously performed, a specific specification is performed once. for each monochrome job is completed, the developing device 3 (e.g., the developing device 3a) is moved by rotating approximately 1 to an initial standby position P ₀ from the developing position P _1, the following specific monochromatic job is designated, again initial standby Moving from the position P ₀ to the development position P ₁ , a specific single color job is performed.
At this time, the developing device 3a to be used for the development has the developing position P ₁ → the standby position P ₂ → the standby position P ₃ → the standby position P ₄ → the initial stage in accordance with the rotation operation of the rotary holder 4 after the image forming job is completed. It moves from the standby position P _{0 to the} development position P ₁ . During one revolution before returning again to the developing position P _1, the developing unit agitation transport member 7 (7a, 7b) in 3a is located in the drive stopped state, stirring with the rotation operation of the rotary holder 4 conveying member 7 The developer at the part corresponding to (7a, 7b) moves along the transport direction of the stirring transport member 7. However, in the developing device 3a used for development, the developer moved by driving the stirring and conveying member 7 (7a, 7b) accompanying the developing operation by the next image forming job is immediately leveled.
However, in the low-use developing device 3 (for example, 3b to 3d) that is not used for development for a long time and is not frequently used, as shown in FIGS. 2 (a) and 2 (b), the rotation holder 4 rotates a plurality of times. If it repeats, the stirring conveyance member 7 (7a, 7b) in the low-use developing device 3 (for example, 3b to 3d) is in a driving stop state, and the stirring conveyance member 7 (7a , 7b) sequentially moves along the conveying direction of the agitating and conveying member 7 (see arrows A and B in FIG. 2B). As described above, in the low-use developing device 3 (for example, 3b to 3d), as the rotational speed of the rotating holder 4 increases, the amount of developer movement increases, and the developer bias increases, resulting in developer distribution. Will be sparse and dense. When the low-use developer 3 is subjected to development in a state where the bias of the developer exceeds a certain limit, even if the layer thickness of the developer is regulated by the layer thickness regulating member, the layer thickness difference is reduced. It cannot be eliminated, and image quality defects such as density unevenness tend to occur.
It should be noted that the developer bias phenomenon described above can occur even when a specific single color job (for example, a single color black job) is continuously performed. For example, when performing a developer discharging operation for a specific developing device, when performing an operation of writing various types of operation information to a communicable recording medium, or image forming that controls the image forming position and image forming density When process control is performed, the bias of the developer in the low-use developer is accelerated because the other developer is forcibly rotated as the specific developer is moved to the development position. Will be.

In the present embodiment model, the development control device 20 is devised to improve such image quality defects.
That is, in the present embodiment model, the development control device 20 includes a rotation amount measuring unit 21 that measures the rotation amount of the rotation holder 4 and a development drive amount that measures the drive amount associated with the developing operation of each developing device 3. The driving amount associated with the developing operation by the developing driving amount measuring unit 22 in a predetermined period corresponding to the rotating amount of the rotating holder 4 measured by the measuring unit 22 and the rotating amount measuring unit 21 is less than or equal to a predetermined value (also 0) The low-use developing device 3 (for example, 3b to 3d) is present, the low-use developing device so as to equalize the deviation of the developer distribution at the portion corresponding to the stirring and conveying member 7 (7a, 7b). 3 is provided with idle driving control means 24 for idly driving for a predetermined time.
Here, the “rotation amount” of the rotation amount measuring means 21 includes a rotation speed, a rotation time, and the like. Further, the development drive amount measuring means 22 measures the drive amount accompanying these regardless of the development operation and the idle drive. The “driving amount” here includes a wide range of driving time and rotational speed of the agitating and conveying member 7. In addition, for example, depending on the type of image forming job, it is clear that other color developing devices are not used in the case of a specific single color job, so the development drive amount is indirectly measured from the type of image forming job. Embodiments are also included.

Further, in the idle drive control unit 24, the low-use developing device 3 exists in the situation where a poor image quality is observed due to the deviation of the developer distribution in the portion corresponding to the stirring and conveying member 7 with respect to the setting method of the specified amount. use may be to set a predefined specified amount relates to the amount of rotation of the rotary holder 4 leading to conditions, such as all the color components after a specified monochrome job by a specific single-color image was performed continuously predetermined times to It is possible to set the specified number of continuous times of a specific single color job in a state where density unevenness is seen in the formed image when a composite color job with a composite color image is executed.
Further, the timing control of the idle drive control means 24 may be selected as appropriate, but from the viewpoint of not hindering the imaging job, the low-use developing device 3 is idled after the imaging job is completed. It is preferable. Further, the idle drive control unit 24 eliminates the necessity of performing idle drive control when an image forming job capable of improving the disturbance of the developer in the low-use developing device 3 is performed. The rotation amount of the rotating holder 4 by the rotation amount measuring means 21 does not reach a predetermined amount while the low-use developing device 3 whose drive amount associated with the developing operation measured at 22 is less than or equal to a predetermined amount exists. When a composite color job using all color components is executed for the low-use developing device 3 under the conditions, the count value of the rotation amount measuring means 21 may be returned to zero.

-Aspect with added developer discharge mechanism-
Further, the developing device 3 mounted on the rotary developing device 2 may be provided with a developer discharging mechanism.
In this case, the developing device 3 is provided in a part of the developing container 5 in addition to the developing container 5, the developer holding body 6, and the plurality of stirring and conveying members 7 (7 a, 7 b), and can discharge excess developer. What is necessary is just to provide the developer discharge port 9.
In this case, the developer discharge port 9 may be kept open at all times, or in a mode in which an opening / closing lid is provided and when the excess developer exceeding a predetermined amount acts on the opening / closing lid, the opening / closing lid is opened and the excess developer is discharged. Good.
In such an aspect in which the developer discharging mechanism is provided, a configuration in which a developer replenishing mechanism as described later is provided and a new developer is replenished from the developer replenishing port 8 is often adopted. In this case, as a new developer replenishing method, the toner and the carrier may be replenished separately, or both may be mixed and replenished.

In this embodiment, as shown in FIGS. 2 (a) and 2 (b), when the low-use developing device 3 is rotated a plurality of times by the rotation holding body 4, the developer is biased, so that a developer discharging operation failure may occur. . This defective developer discharge operation can be considered both when the developer is excessively biased at the developer discharge port 9 and when the developer becomes too small. In the former case, a situation occurs in which the excessive developer is unnecessarily discharged from the developer discharge port 9, while in the latter case, the excess developer should be discharged immediately, but the discharge operation is reached. Will be delayed in time.
In order to avoid such a situation, in the present embodiment model, as the development control device 20, the rotation amount measuring means 21 that measures the rotation amount of the rotation holder 4 and the driving accompanying the developing operation of each developing device 3. The rotation amount measuring means 21 while the developing drive amount measuring means 22 for measuring the amount and the low-use developing device 3 whose drive amount associated with the developing operation measured by the development drive amount measuring means 22 is equal to or less than a predetermined value exist. For a predetermined time with respect to the low-use developer 3 so as to equalize the deviation of the developer distribution in the vicinity of the developer discharge port 9 under the condition that the rotation amount of the rotary holder 4 reaches a predetermined amount. What is necessary is just to provide the idling drive control means 24 to idly drive.
At this time, as a method for setting the prescribed amount, the prescribed amount is assumed assuming a situation immediately before the developer discharging operation failure from the developer discharge port 9 due to the deviation of the developer distribution in the vicinity of the developer discharge port 9 occurs. Is preferably set.

-Mode with developer replenishment mechanism-
Further, the developing device 3 mounted on the rotary developing device 2 may include a developer supply mechanism 10.
The developer replenishing mechanism 10 may be one that replenishes toner in a mode in which no developer discharging mechanism is provided, and a carrier is included in a mode in which a developer discharging mechanism is provided. The toner may be replenished.
In the present embodiment model, the developer supply mechanism 10 extends along the rotation axis direction of the developer holder 6 and is connected to a part of the developer circulation path 5 a of the developer container 5 via the delivery port 12. And a developer transport member 13 that is disposed in the developer replenishment path 11 and that is rotated to drive and transport the developer toward the delivery port 12.
In particular, as a typical embodiment of the developer supply mechanism 10, it extends along the rotation axis direction of the developer holder 6 and is connected to a part of the developer circulation path 5 a of the developer container 5 via the delivery port 12. A developer replenishing path 11 is provided, and a developer transporting member 13 is provided in the developer replenishing path 11 so that the developer is driven and transported toward the delivery port 12 by rotating, and the developer transporting member 13 rotates. A mode in which the developer in the developer replenishment path 11 can flow backward in the direction away from the delivery port 12 as the rotation holding body 4 rotates at the time of stopping is mentioned.

In such an embodiment in which the developer replenishing mechanism 10 is added, as shown in FIGS. 2A and 2B, for example, the developer transport member 13 of the low-use developer 3 is in a drive stopped state. When the rotating holder 4 rotates a plurality of times in this state, as shown in FIG. 1B, the developer flows backward in the direction away from the delivery port 12 as shown by the arrow C in FIG. If the backflow movement amount becomes too large, the developer replenishing operation will be hindered. Alternatively, there is a concern that the amount of developer in the low-use developing device 3 decreases, and layer formation with the developer becomes insufficient, resulting in poor image quality.
Therefore, in the present embodiment model, the development control device 20 is devised so as not to hinder the developer replenishing operation and the image quality defect.
In the present embodiment model, as the development control device 20, a rotation amount measuring means 21 that measures the rotation amount of the rotation holder 4 and a developer replenishment operation by the developer transport member 13 of the developer replenishment mechanism 10 are accompanied. The revolving amount is measured while the replenishing driving amount measuring means 23 for measuring the driving amount and the low usage developer 3 whose driving amount associated with the developer replenishing operation measured by the replenishing driving amount measuring means 23 is equal to or less than a predetermined value. The development of the low-use developer 3 so that the reverse flow of the developer in the developer supply path 11 is restored under the condition that the rotation amount of the rotation holder 4 by the measuring means 21 reaches a predetermined amount. What is necessary is just to provide the idle drive control means 24 which idle-drives the agent supply mechanism 10 (or the developer transport member 13) for a predetermined time.

―Concentration control―
The development control device 20 needs to perform density control on the created image.
At this time, since the low-use developing device 3 that requires idle driving control by the idle driving control means 24 has a biased developer distribution, density control tends to be inaccurate when density control is performed in this state. .
Therefore, in the present embodiment, as the development control device 20, the density control means 25 that controls the toner density by directly or indirectly detecting the toner density, and the developing device during idle driving by the idle driving control means 24. 3 may be provided with a prohibiting means 26 for prohibiting the toner density control operation by the density control means 25.
Further, the development control device 20 includes the density control unit 25 and a permitting unit 27 that allows the density control unit 25 to perform a toner density control operation on the developing device 3 after the idle drive by the idle drive control unit 24 is completed. Can be provided.
Here, the toner density detection method used in the density control means 25 may be a method in which the toner density of the developer in the developing device 3 is directly detected, or a toner image is formed on the image carrier 1 and the density is determined. An indirect detection method may be used.

Hereinafter, the present invention will be described in more detail based on embodiments shown in the accompanying drawings.
Embodiment 1
―Overall configuration of image forming device―
FIG. 3 shows Embodiment 1 of an image forming apparatus to which the present invention is applied.
In the figure, an image forming apparatus includes an image carrier 30 such as a photoconductor, and a rotary developing device 40 that can visualize an electrostatic latent image formed on the image carrier 30 in a single color or a full color. It is equipped with.
Here, for example, an electrophotographic method is adopted as an image forming method on the image carrier 30, and after charging the image carrier 30 with a charger (not shown), an electrostatic latent image is written by the exposure device. It is a thing. The image carrier 30 may be any one that holds an electrostatic latent image and visualizes it with the rotary developing device 40. A dielectric is used as the dielectric, and a charger, ions, etc. are used as the dielectric. The electrostatic latent image may be written by a writing device.

Further, the rotary developing device 40 has a rotatable rotation holding body 41, and a plurality of developing devices 50 (specifically, 50a to 50d) are mounted on the rotation holding body 41. Each of the developing devices 50 uses, for example, two-component developers of four colors of black (K), yellow (Y), magenta (M), and cyan (C).
In particular, in the present embodiment, the rotary developing device 40 has a development position P ₁ as a setting position of each developing device 50 and a position facing the image holding body 30, and is approximately in the rotational direction of the rotary holding body 41. The standby positions P _{2 to} P ₄ are set every 90 degrees, and the initial standby position P ₀ where none of the developing devices 50 faces the development position P ₁ is set.

―Overall configuration of developer―
In this embodiment, the developing device 50, for example, as shown in FIGS. 4 and 5, the developer is accommodated to face the image carrier 30 at the developing position P ₁ comprising an open and color component toner and carrier And a roll-shaped developer holder 52 is rotatably disposed at a portion facing the opening of the developer container 51, and on the back side of the developer holder 52 of the developer container 51. Is configured such that a pair of agitating and conveying members 53 and 54 are rotatably arranged along the rotation axis direction of the developer holding member 52, and a partition plate 55 is provided in the developing container 51 positioned between the agitating and conveying members 53 and 54. The developer passage ports 56 and 57 are opened near both ends of the partition plate 55, and a developer circulation path 58 through which the developer conveyed by the agitating and conveying members 53 and 54 circulates through the passage ports 56 and 57. It is intended to secure The
Here, the developer holding body 52 is provided with a magnetic pole member 52b in which an appropriate number of magnetic poles are arranged inside a rotatable non-magnetic cylindrical body 52a. A layer thickness regulating member 59 that normally regulates the layer thickness of the developer conveyed to the area is provided.
The pair of agitating and conveying members 53 and 54 are, for example, provided with spiral blades 61 and 62 around the rotating shaft 60, and the agitating and conveying members 53 and 54 have the same helical blades 61 and 62. The developer is transported in the opposite direction when rotated in the direction.
Note that reverse spiral blades 63 and 64 are provided at both ends of the agitating and conveying members 53 and 54 so that the developer can be circulated and conveyed through the passage ports 56 and 57.

―Developer supply mechanism―
Further, in the present embodiment, the developing device 50 includes a developer supply mechanism 70. In this embodiment, since a developer discharge mechanism to be described later is added, toner containing a carrier is used as the replenishment developer.
The developer supply mechanism 70 is provided with a developer supply path 71 on the side away from the developer holder 52 along the longitudinal direction of the developer circulation path 58 of the developer container 51, and along the developer supply path 71. The developer conveying member 72 is rotatably arranged, and a delivery port 73 between the developer supply path 71 and the developer circulation path 58 is provided on the downstream side of the developer conveying direction by the developer conveying member 72. It is what I did.
The developer conveying member 72 is provided with a spiral blade 76 around the rotary shaft 75 in the same manner as the agitating / conveying members 53 and 54, and the rotating blade 41 rotates when the helical blade 76 is in a drive stopped state. Then, the developer can be moved in a direction away from the delivery port 73 in the developer supply path 71.
Furthermore, a developer supply port 74 is provided upstream of the developer supply path 71 in the developer transport direction, and a developer supply container 80 is connected to the developer supply port 74.
The developer supply container 80 has, for example, a cylindrical shape, and is divided into a storage chamber and a collection chamber. A spiral spring-shaped conveyance member is provided inside the storage chamber, and is connected via a developer supply port 74. Thus, the developer is supplied to the developer supply path 71.

―Developer discharge mechanism―
In the present embodiment, the developing device 50 includes a developer discharge mechanism 90 that can discharge excess developer.
As shown in FIGS. 5 and 6A and 6B, the developer discharging mechanism 90 is a portion in which the stirring and conveying member 54 on the side away from the developer holding body 52 in the developer circulation path 58 is accommodated. And provided on the side wall of the developing container 51 facing the passage port 56.
The developer discharge mechanism 90 has a developer discharge port 91 opened at an appropriate position on the side wall of the developer container 51, and an open / close lid 92 is rotatably provided in the developer discharge port 91. The open / close lid 92 assists the developer discharging operation when the developer in the developer circulation path 58 increases and the amount of the developer exceeds a predetermined amount. When the position of the toner is changed, the developer is closed to prevent excessive discharge of the developer.

―Control system―
FIG. 7 shows a control system for the rotary developing device according to this embodiment.
In the figure, reference numeral 100 denotes a control device composed of a microcomputer or the like, and performs drive control and density control of the rotary developing device 40.
Target drive control of the rotary developing device 40, developer carrier 52 of the drive motor 102, the developing unit 50 at the developing position P ₁ for driving the rotary holder 41 via a drive transmission mechanism 101 such as a gear, stirred a driving motor 104 for driving the conveying member 53, 54 via a drive transmission mechanism 103 such as a gear, drives through the developing unit 50 drive transmission mechanism 105 such as a gear to the developer conveying member 72 at the developing position P ₁ A rotation detector 120 that is a drive motor 106 and detects an instruction signal from the operation unit 110 such as an image forming mode (monochromatic black mode (BW mode), full color mode (FC mode)) or the rotation of the rotation holder 41. Is received by the control device 100, and a predetermined drive control signal is sent to each of the drive motors 102, 104, and 106. As the rotation detector 120, an encoder that detects the rotation operation of the rotation holder 41 is used.
Further, the density control of the rotary developing device 40 is performed by, for example, a toner in the developer from a density detector (for example, using a detector that detects magnetic permeability) 130 that can detect the toner density of the developer in the developer 50. The density is grasped, and the developer supply operation is controlled based on the density.
The density detection method is not limited to the method of directly detecting from the developer in the developing device 50. For example, as shown by a two-dot chain line in FIG. May be detected by the optical density detector 131.

In particular, in the present embodiment, the control device 100 executes the following processing in addition to the basic operation control described above for the rotary developing device 40.
(1) Image quality defect inspection process due to developer bias (2) Developer discharge operation defect inspection process (3) Developer replenishment operation defect inspection process (4) Density control restriction process

(1) Image quality defect inspection processing due to developer bias (see FIGS. 8 and 11)
As shown in FIG. 8, the control device 100 determines whether or not the image forming job has ended. If the image forming job has ended, whether the image forming job is in the monochrome black mode (BW mode) or not. If it is a monochrome black mode, it is checked whether the count value of the rotation speed counter is equal to or greater than a specified value m.
Here, as shown in FIG. 11, the rotation number counter is for counting the rotation number of the rotary developing device 40, and the specified value m is the rotation of the rotation holder 41 by the low-use developing device 50. This is set on the assumption that an image quality defect occurs due to the bias of the developer when it is used several times after being rotated in accordance with the operation.
When the count value of the rotation number counter is equal to or greater than the specified value m, the presence / absence of the low-use developer 50 having a development drive amount of 0 is checked. In this example, it is understood that the yellow, magenta, and cyan developing devices are the low-use developing devices 50 unless the full-color mode is specified. Therefore, when the single-color black mode continues for a predetermined number of times, the low-use developing device 50 Judge that it exists.
Then, the low use developing unit 50 a predetermined time during idle driving in a state of moving the low use developing device 50 to the developing position P ₁ by controls the driving motor 102 and the drive motor 104 if an empty drive is completed At this point, the developing drive amount of the developing device 50 is cleared to zero, and then the rotation number counter is cleared to zero.
On the other hand, when the image forming job is in the full color mode, the low-use developing device 50 is used for development. Therefore, the idle driving control for the low-use developing device 50 is not necessary at the stage of the development. Use to clear the rotation counter to zero.

(2) Developer discharge operation failure inspection process (see FIGS. 9, 11, and 12)
As shown in FIG. 9, the control device 100 determines whether or not the image forming job has ended. If the image forming job has ended, the control device 100 determines whether or not the count value of the rotation number counter is equal to or greater than a specified value m1. Check.
Here, the specified value m1 is a situation in which the developer discharge operation failure occurs due to the deviation of the developer when the low-use developer 50 is rotated a plurality of times in accordance with the rotation operation of the rotary holder 41 and then used. This is set assuming that
When the count value of the rotation number counter is equal to or greater than the specified value m1, the presence / absence of the low-use developer 50 having a development drive amount equal to or less than a predetermined value is checked.
In this example, the determination may be made from the image forming mode as described above, but it may be checked based on, for example, the development drive amount measurement process of FIG. Note that the present example can also be applied to the process (1).
Thereafter, the low use developing unit 50 a predetermined time during idle driving in a state of moving the low use developing device 50 to the developing position P ₁ by controls the driving motor 102 and the drive motor 104 if an empty drive ends At this point, the developing drive amount of the developing device 50 is cleared to zero, and then the rotational speed counter is cleared to zero.

(3) Developer replenishment operation failure inspection process (see FIGS. 10, 11, and 12)
As shown in FIG. 9, the control device 100 determines whether or not the image forming job has ended, and if the image forming job has ended, whether or not the count value of the rotation number counter is equal to or greater than a specified value m2. Check.
Here, the specified value m2 indicates a situation in which the developer replenishment operation failure by the developer replenishment mechanism occurs when the low use developer 50 rotates a plurality of times in accordance with the rotation operation of the rotation holder 41 and is used. It is set assuming.
When the count value of the rotation speed counter is equal to or greater than the specified value m2, it is checked whether or not there is a low-use developing device 50 whose replenishment drive amount is equal to or less than a predetermined value.
In this example, the check may be performed based on, for example, the replenishment drive amount measurement process in FIG.
Thereafter, if there is a low-use developer 50, the drive motor 102 and the drive motor 106 are controlled so that the low-use developer 50 is moved to the development position P ₁ and the developer supply mechanism 70 is idly driven for a predetermined time. When the idle driving is completed, the replenishment driving amount of the developing device 50 is cleared to zero, and then the rotation number counter is cleared to zero.

(4) Density control restriction processing (see FIG. 13)
The control device 100 checks whether or not it is the density control execution timing, and then checks whether or not the low-use developer 50 or the developer replenishment mechanism 70 of the low-use developer 50 needs to be idle driven. If there is a non-acting effect, the concentration control is limited.
Then, the density control is allowed to be performed when the idle use of the low-use developer 50 or the developer replenishment mechanism 70 of the low-use developer 50 is completed.

As described above, in each of the processes (1) to (3), as shown in FIG. 14A, the developer in the developer circulation path 58 of the low-use developer 50 is biased, Although the developer G is in a reverse flow state in the developer supply path 71 of the developer supply mechanism 70, since predetermined idle drive control is performed on this, as shown in FIG. 14B. The deviation of the developer G in the developer circulation path 58 is leveled, and the developer G in the developer supply path 71 is returned to the original position before the backflow.
In addition, since (4) density control restriction processing is performed on such idle drive control, the situation where density control is performed incorrectly can be effectively avoided.

Example 1
The image forming apparatus according to Embodiment 1 is referred to as Example 1, and (1) a specific value m in image quality defect inspection processing associated with developer bias is specifically set.
When tests 1 to 6 were performed and image quality defects were examined when the full color mode was subsequently executed, the results shown in FIG. 15 were obtained.
The test condition in FIG. 15 is a full color mode after a plurality of jobs in the single color black mode (single Kuro), and the image is formed under a stress condition based on an instruction to create an image of one halftone page. In other words, this stress condition is an operation in which the rotation of the rotating holder frequently enters every time the developing operation for creating an image of one page of the black developer is performed, and the developer bias occurs in the other color developers. It will be easier.
In FIG. 15, even when the full color mode is executed after repeating the monochrome black mode 40 jobs, image quality does not deteriorate. However, when the full color mode is executed after repeating the monochrome black mode 50 jobs, for example, the spiral shape of the agitating and conveying member It was confirmed that this leads to poor image quality due to uneven density like marks.
For this reason, in this embodiment, assuming that the specified value m is a single color black mode 40 job, the low-use developer is idled for a predetermined time for each single color black mode 40 job (for example, equivalent to one sheet of JIS standard A4L recording material). As a result, it was confirmed that poor image quality due to developer bias was effectively avoided.

Example 2
When the image forming apparatus according to Embodiment 1 is in Example 2 and (4) density control restriction processing is performed, as shown in FIG. 16A, the image density detection pattern of each color component is drawn in an accurate state. However, in the comparative example in which the density control process is performed in the situation where the idle drive control is required without performing the process (4), as shown in FIG. 16B, magenta, It was confirmed that the cyan image density detection pattern was abnormally thin.

(A) is explanatory drawing which shows the outline | summary of embodiment model of the image forming apparatus with which this invention is applied, (b) is a structural example of the developing device mounted in the rotary developing device of the image forming apparatus of (a). FIG. (A) is explanatory drawing which shows the multiple rotation phenomenon of the low-use developing device which arises with a rotary developing device, (b) is explanatory drawing which shows the biasing operation | movement of a developer at that time. 1 is an explanatory diagram showing an overview of an image forming apparatus according to Embodiment 1. FIG. It is explanatory drawing which shows the detail of the developing device mounted in the rotary developing apparatus shown in FIG. FIG. 5 is a cross-sectional explanatory view taken along line VV in FIG. 4. (A) is explanatory drawing which shows the detail of the developer discharge port vicinity of Embodiment 1, (b) is the principal part perspective view. FIG. 3 is an explanatory diagram showing a control system (drive control system, density control system) used in the first embodiment. 7 is a flowchart illustrating an image quality defect inspection process associated with developer bias. 6 is a flowchart illustrating a developer discharge operation failure inspection process. 6 is a flowchart showing a developer replenishment operation failure inspection process. It is a flowchart which shows the rotation speed counting process of a rotary developing device. (A) is a flowchart showing the developing drive amount measurement processing of the developing device, (b) is a flowchart showing the replenishment driving amount measurement processing of the developing device. It is a flowchart which shows a density control restriction | limiting process. (A) is explanatory drawing which shows the bias state of the developer before idling of a low use developing device, (b) is explanatory drawing which shows the uniform state of the developer after idling of a low use developing device. FIG. 6 is an explanatory diagram illustrating an example of setting a prescribed value for image quality defect inspection processing associated with developer bias using the image forming apparatus according to the first exemplary embodiment. (A) is explanatory drawing which shows the image density detection pattern which performed the density control process using the image forming apparatus which concerns on Example 2, (b) is the image density detection pattern by the comparative example which performs a density control process during idle driving | running | working It is explanatory drawing which shows.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Image holding body, 2 ... Rotating developing device, 3 (3a-3d) ... Developing device, 4 ... Rotating holding body, 5 ... Developing container, 5a ... Developer circulation path, 6 ... Developer holding body, 7 ( 7 ... 7a, 7b) ... stirring transport member, 8 ... developer supply port, 9 ... developer discharge port, 10 ... developer supply mechanism, 11 ... developer supply path, 12 ... delivery port, 13 ... developer transport member, 20 ... Development control device, 21... Rotation amount measurement means, 22... Development drive amount measurement means, 23... Replenishment drive amount measurement means, 24. , P ₀ ... initial standby position, P ₁ ... development position, P _{2 to} P ₄ ... standby position

Claims (12)

An image carrier for holding an electrostatic latent image;
A plurality of developing devices are mounted on a rotary holding body that can be rotated in one direction so that the electrostatic latent image held on the image holding body is visualized as a single color or a composite color. A rotary developing device that stops rotating at a standby position other than the developing position, and that the developing device is driven to be developable in a state where the developing device stops rotating at the developing position;
An image forming apparatus including a development control device that controls the rotary development device,
Each developer of the rotary developing device includes a developer container that contains a two-component developer containing toner and a carrier and has a developer circulation path through which the developer circulates;
A developer holder that faces the development opening of the developer container and holds the developer to rotate and convey it;
A plurality of agitation transport members that agitate and convey the developer along the developer circulation path by extending and rotating along the rotation axis direction of the developer holding member in the developer circulation path of the developer container. Prepared,
The development control device includes:
A rotation amount measuring means for measuring the rotation amount of the rotating holder;
Development drive amount measuring means for measuring the drive amount associated with the developing operation of each developing device;
There is a low-use developing device in which the drive amount associated with the developing operation measured by the development drive amount measuring unit is less than or equal to a predetermined period for a predetermined period according to the rotation amount of the rotation holder measured by the rotation amount measuring unit. In this case, the image forming apparatus includes: an idle drive control unit that idles the low-use developer for a predetermined time so as to equalize a deviation of the developer distribution in a portion corresponding to the agitating and conveying member. . The image forming apparatus according to claim 1.
The idling drive control means is configured to rotate the rotating holder to reach a condition where the low-use developer is present, assuming a situation in which image quality failure is observed due to a deviation in developer distribution in a portion corresponding to the agitating and conveying member. An image forming apparatus characterized in that a predetermined amount is set in advance for the amount. The image forming apparatus according to claim 1.
The idle drive control means shows uneven density in the formed image when a specific color job using a specific single color image is continuously executed a predetermined number of times and then a composite color job using a composite color image using all color components is executed. An image forming apparatus characterized in that the number of continuous times of a specific single color job in a situation is set as a specified amount. The image forming apparatus according to claim 1.
The image forming apparatus, wherein the idle drive control unit idles the low-use developer after completion of the image forming job. The image forming apparatus according to claim 1.
The idling drive control means is configured so that the rotation amount of the rotation holder by the rotation amount measuring means is previously determined while there is a low-use developing device in which the drive amount accompanying the developing operation measured by the development drive amount measuring means is not more than a predetermined value. When a composite color job using all color components is executed for the low-use developer under a condition that does not reach the specified amount, the count value of the rotation amount measuring unit is returned to zero. An image forming apparatus. An image carrier for holding an electrostatic latent image;
A plurality of developing devices are mounted on a rotary holding body that can be rotated in one direction so that the electrostatic latent image held on the image holding body is visualized as a single color or a composite color. A rotary developing device that stops rotating at a standby position other than the developing position, and that the developing device is driven to be developable in a state where the developing device stops rotating at the developing position;
An image forming apparatus including a development control device that controls the rotary development device,
Each developer of the rotary developing device includes a developer container that contains a two-component developer containing toner and a carrier and has a developer circulation path through which the developer circulates;
A developer holder that faces the development opening of the developer container and holds the developer to rotate and convey it;
A plurality of agitating and conveying members for agitating and conveying the developer along the developer circulation path by extending and rotating along the rotation axis direction of the developer holding body in the developer circulation path of the developer container; and
A developer replenishing port provided in a part of the developing container and capable of replenishing a new developer;
The development control device includes:
A rotation amount measuring means for measuring the rotation amount of the rotating holder;
Development drive amount measuring means for measuring the drive amount associated with the developing operation of each developing device;
The rotation amount of the rotating holder by the rotation amount measuring unit is set to a predetermined amount while a low-use developing device whose driving amount associated with the developing operation measured by the development driving amount measuring unit is not more than a predetermined value exists. And an idle drive control unit that idle-drives the low-use developer for a predetermined time so as to equalize a deviation in developer distribution at a portion corresponding to the agitating and conveying member under a predetermined condition. Forming equipment. An image carrier for holding an electrostatic latent image;
A plurality of developing devices are mounted on a rotary holding body that can be rotated in one direction so that the electrostatic latent image held on the image holding body is visualized as a single color or a composite color. A rotary developing device that stops rotating at a standby position other than the developing position, and that the developing device is driven to be developable in a state where the developing device stops rotating at the developing position;
An image forming apparatus including a development control device that controls the rotary development device,
Each developer of the rotary developing device includes a developer container that contains a two-component developer containing toner and a carrier and has a developer circulation path through which the developer circulates;
A developer holder that faces the development opening of the developer container and holds the developer to rotate and convey it;
A plurality of agitating and conveying members for agitating and conveying the developer along the developer circulation path by extending and rotating along the rotation axis direction of the developer holding body in the developer circulation path of the developer container; and
A developer outlet provided in a part of the developer container and capable of discharging excess developer;
The development control device includes:
A rotation amount measuring means for measuring the rotation amount of the rotating holder;
Development drive amount measuring means for measuring the drive amount associated with the developing operation of each developing device;
The rotation amount of the rotating holder by the rotation amount measuring unit is set to a predetermined amount while a low-use developing device whose driving amount associated with the developing operation measured by the development driving amount measuring unit is not more than a predetermined value exists. An image forming apparatus comprising: an idle drive control unit that idles the low-use developer for a predetermined time so as to equalize a deviation in developer distribution near the developer discharge port under a predetermined condition. . The image forming apparatus according to claim 7.
The idle drive control means sets a prescribed amount assuming a situation immediately before a developer discharge failure from the developer discharge port occurs due to a deviation in developer distribution near the developer discharge port. An image forming apparatus, comprising: The image forming apparatus according to claim 1, 6 or 7.
Further, the developer holding member is disposed in a developer supply path that extends along the rotation axis direction of the developer holding body and is connected to a part of the developer circulation path of the developer container via a delivery port, and develops by rotating. A developer transport member that is driven and transported toward the delivery port,
The development control device further includes a replenishment drive amount measuring means for measuring a drive amount associated with a developer replenishment operation by the developer transport member;
A prescription in which the amount of rotation of the rotating holder by the rotation amount measuring means is defined in advance while there is a low-use developing device in which the driving amount associated with the developer replenishment operation measured by the replenishment driving amount measuring means is less than a predetermined value. An idle drive control means for idly driving the developer transport member of the low-use developer for a predetermined time so as to restore the developer backflow in the developer supply path under the condition that the amount has reached An image forming apparatus. The image forming apparatus according to claim 1, 6 or 7.
Furthermore, a developer replenishment path extending along the rotation axis direction of the developer holder and connected to a part of the developer circulation path of the developer container via a delivery port is provided. Is provided with a developer conveying member that is rotated and driven to convey the developer toward the delivery port, and when the developer conveying member stops rotating, the developer in the developer replenishment path when the rotation holder rotates. There comprises a backflow capable developer supply mechanism in a direction away from the delivery opening,
The development control device further includes a replenishment drive amount measuring means for measuring a drive amount associated with a developer replenishment operation by a developer transport member of the developer replenishment mechanism,
A prescription in which the amount of rotation of the rotating holder by the rotation amount measuring means is defined in advance while there is a low-use developing device in which the driving amount associated with the developer replenishment operation measured by the replenishment driving amount measuring means is less than a predetermined value. An idle driving control means for idly driving the developer replenishing mechanism of the low-use developer for a predetermined time so as to restore the developer backflow in the developer replenishing path under the condition that the amount has reached An image forming apparatus. The image forming apparatus according to any one of claims 1, 6, 7, 9 and 10.
The development control device includes a density control unit that directly or indirectly detects the toner density and controls the toner density;
An image forming apparatus comprising: a prohibiting unit that prohibits a toner density control operation by the density control unit for the developing unit during the idle driving by the idle driving control unit. The image forming apparatus according to any one of claims 1, 6, 7, 9 and 10.
The development control device includes a density control unit that directly or indirectly detects the toner density and controls the toner density;
An image forming apparatus comprising: a permitting unit that allows the developing device to perform a toner density control operation after the idle driving by the idle driving control unit.

Images