JP2011008159A - Image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus which discharges impurities, such as developer aggregate entering a surface layer foaming cell of a toner supply rotating body whose surface layer is formed of an elastic foaming material layer, or aggregate resulting from toner external additive, in a non-magnetic one-component developing type developing device in predetermined timing.SOLUTION: In the image forming apparatus, the toner supply rotating body is driven at predetermined full rotational speed or predetermined decreased rotational speed lower than the full rotational speed, and full-speed driving time at the full rotational speed of the toner supply rotating body is accumulated and recorded. When the cumulative full-speed driving time attains predetermined time T1, the toner supply rotating body is decelerated and driven at the decreased rotational speed for predetermined time T2 in the predetermined timing (for example, when an image is not formed).

Description

  The present invention relates to a copying machine, a printer, and a facsimile machine capable of forming an electrostatic latent image on an electrostatic latent image carrier by an electrophotographic method, an electrostatic recording method, etc., and developing the image with a developing device to form a toner image. Alternatively, the present invention relates to an image forming apparatus such as a multi-function machine in which two or more of these are combined.

  An image forming apparatus such as a copying machine, a printer, a facsimile machine, or a combination machine combining two or more of these, which forms an electrostatic latent image on an electrostatic latent image carrier and develops it to form a toner image. Various types of developing devices are known, and the following are among them.

A non-magnetic one-component developing type developing device using a developer mainly composed of non-magnetic toner (so-called non-magnetic one-component developer),
A toner carrying rotator for applying toner to the electrostatic latent image on the electrostatic latent image carrier;
A toner supply rotator that supplies toner to the toner carrying rotator and scrapes off toner remaining on the toner carrying rotator without being consumed in development;
The toner is supplied to the toner carrying rotator from the toner supply rotator and is brought into contact with the toner carrying rotator for regulating the layer thickness of the toner on the toner carrying rotator which is transported to the development area of the electrostatic latent image. The toner supply rotating body is a developing device in which a layer including a surface is formed of an elastic foam material.

  In this type of developing device, the toner layer thickness of the toner supplied from the toner supply rotator to the toner carrying rotator is regulated by a blade type toner regulating member that is in contact with the toner carrying rotator. In addition, it is generally charged by frictional charging with the regulating member or by applying a bias to the regulating member and conveyed to the electrostatic latent image developing area. In addition, the toner that returns to the developing device with the rotation of the toner carrying rotator without being consumed for development is often discharged by a charge eliminating member so that the toner supply rotator can easily scrape off the toner carrying rotator. It has been broken.

  In any case, in the developing device of the non-magnetic one-component developing system, the external additive is gradually dropped from the toner or the external additive is buried in the toner body as it is repeatedly used. The toner deteriorates. As the amount of deteriorated toner increases in this way, the toner charge amount decreases and development failure occurs.

  Therefore, in Japanese Patent Application Laid-Open No. 2007-293122, in order to suppress the deterioration of the toner, the hardness of the surface portion of the toner supply rotator is reduced so that the toner is transferred between the toner supply rotator and the toner carrying rotator. In order to reduce the applied physical stress, it has been proposed to form a layer including the surface of the toner supply rotating body with an elastic foam material made of, for example, polyurethane foam (polyurethane foam).

  Thus, when the layer including the surface of the toner supply rotator is formed of an elastic foam material, the surface layer of the toner supply rotator becomes soft, and the toner scraping performance from the toner carrying rotator decreases. Therefore, in order to suppress a decrease in the toner scraping performance, a layer including a surface made of an elastic foam material of the toner supply rotating body is formed as a single foam cell (an independent foam cell, not a foam cell communicating with other foam cells). It is also practiced to increase the density of the single-bubble cell.

JP 2007-293122 A

However, when the layer including the surface of the toner supply rotating body is formed of an elastic foam material, impurities such as developer aggregates and aggregates resulting from the toner external additive released from the toner are formed in the foam cells in the layer including the surface. Is clogging up. Such agglomerates are caused by the physical force that the developer receives in contact with the rotating member or the toner regulating member in the developing device as the developing device is used, or the heat generated by the continuous use of the developing device. Will occur.
Such agglomerates are large lumps having an outer diameter of, for example, about several tens of μm to one hundred μm as compared with a normal toner.

  As described above, when the foam cell in the layer including the surface made of the elastic foam material of the toner supply rotator is a single cell, and the density of the cell is increased, it becomes difficult for the toner or the like to enter the inner part of the toner supply rotator. Therefore, impurities such as aggregates are more easily clogged in the foam cell in the layer including the surface of the toner supply rotating body.

  In this way, when the foam cell in the layer including the surface of the toner supply rotating body is clogged with impurities such as aggregates, the image forming apparatus prints more than when printing on plain paper, such as when printing on cardboard. When the speed is reduced (for example, reduced to half that when printing on plain paper), and therefore the rotational speed of the toner supply rotating body is also reduced, the impurities clogged in the foam cell are likely to be discharged from the foam cell. Many granular noises are generated on the developed and formed image.

  Accordingly, the present invention can form an electrostatic latent image on an electrostatic latent image carrier, and develop the electrostatic latent image with a developing device to form a toner image. At least one developing device has a corresponding electrostatic latent image. A toner carrying rotator for applying toner to an electrostatic latent image on an image carrier, and a toner that supplies toner to the toner carrying rotator and scrapes off toner remaining on the toner carrying rotator without being consumed by development. And a toner carrying member that regulates a layer thickness of the toner on the toner carrying rotary member supplied to the toner carrying rotary member and conveyed to the developing area of the electrostatic latent image. A toner regulating member in contact with the rotating body, and the toner supply rotating body is an image forming apparatus that is a developing device of a non-magnetic one-component developing system in which a layer including a surface is formed of an elastic foam material. , At least one non-magnetic one-component developing method In the developing device, impurities such as developer aggregates entering the foamed cells in the layer including the surface of the toner supply rotating body and aggregates due to the external additive of the toner can be discharged at a predetermined timing. Accordingly, it is an object of the present invention to provide an image forming apparatus that can suppress the occurrence of image noise due to impurities in an image developed and formed by the developing apparatus, and as a result, can form an image as good as the entire image forming apparatus.

In order to solve the above problems, the present invention
An electrostatic latent image can be formed on the electrostatic latent image carrier, and the electrostatic latent image can be developed with a developing device to form a toner image. At least one developing device can be mounted on the corresponding electrostatic latent image carrier. A toner carrying rotator for applying toner to the electrostatic latent image, a toner supply rotator for supplying toner to the toner carrying rotator and scraping off toner remaining on the toner carrying rotator without being consumed in development; The toner is supplied to the toner carrying rotator from the toner supply rotator and is brought into contact with the toner carrying rotator for regulating the layer thickness of the toner on the toner carrying rotator which is transported to the development area of the electrostatic latent image. An image forming apparatus that is a non-magnetic one-component developing type developing device in which a layer including a surface is formed of an elastic foam material.
About at least one developing device of the non-magnetic one-component developing system,
A toner supply rotator driving unit capable of driving the toner supply rotator at a predetermined full-speed rotation speed or a predetermined decelerated rotation speed slower than the full-speed rotation speed;
A full-speed drive time recording unit for accumulating and recording the full-speed drive time according to the full-speed rotation speed of the toner supply rotator;
After the accumulated full speed drive time recorded in the full speed drive time recording section reaches a predetermined time T1, the toner supply rotary body is instructed to the toner supply rotary body by a predetermined time T2, the deceleration. An image forming apparatus is provided that includes a deceleration drive instruction unit that performs deceleration driving at a rotational speed.

  According to the image forming apparatus of the present invention, at least one developing device supplies a toner carrying rotator for applying toner to the electrostatic latent image on the corresponding electrostatic latent image carrier, and supplies the toner to the toner carrying rotator. A toner supply rotator that scrapes off toner remaining on the toner carrying rotator without being consumed in development, and is supplied from the toner supply rotator to the toner carrying rotator and transported to the development area of the electrostatic latent image. A toner regulating member that is in contact with the toner carrying rotator and regulates a layer thickness of the toner on the toner carrying rotator. This is a developing device of a non-magnetic one-component developing system that is formed.

  In this type of developing device, the foam cell of the layer including the surface made of the elastic foam material of the toner supply rotator may be a so-called open cell, but residual toner after development on the toner-carrying rotator by the toner supply rotator. In order to improve the scraping performance, a layer including a single cell (not an expanded cell connected to another expanded cell but an independent expanded cell) may be used. In addition, the density of the single cell may be increased.

  In any case, in the developing device of the above type, after the accumulated full speed drive time recorded in the full speed drive time recording unit reaches a predetermined time T1, the deceleration drive instructing unit displays the toner supply rotating body. The drive unit is instructed to drive the toner supply rotator at a reduced speed at a predetermined time T2 for a predetermined time T2.

  By such deceleration driving of the toner supply rotator, such as developer aggregates and aggregates caused by external toner additives that have entered the foam cell of the layer including the surface made of the elastic foam material of the toner supply rotator. Impurities are easily discharged from the cell, and thus generation of image noise due to the impurities in the developed and formed image can be suppressed accordingly, and as a result, a good image can be formed as a whole image forming apparatus.

  The deceleration rotational speed is confirmed by an experiment or the like in advance to discharge impurities such as agglomerates that have entered the foam cell of the layer including the surface made of the elastic foam material of the toner supply rotor. What is necessary is just to make it the rotation speed currently made.

  Examples of the decelerating rotational speed include a rotational speed that is half of the rotational speed of the toner supply rotator when printing on plain paper or the like (a rotational speed that may be employed when printing on thick paper such as envelopes). be able to. If the impurities can be discharged from the cell, the rotation speed may be about 1/3 of the rotation speed during normal printing, for example.

  In any case, the reason why impurities such as agglomerates that have entered the foam cell due to the reduction in the rotation speed of the toner supply rotating body is likely to be discharged from the foam cell is that the rotation speed of the toner supply rotating body decreases. As a result of this, more toner is attracted by the rotation of the toner supply rotator and supplied to the toner-carrying rotator than the normal rotation speed of the toner supply rotator. As a result, when impurities such as agglomerates that have already entered the foam cell of the surface layer of the toner supply rotating body approach a member that gives physical force such as a toner regulating member, the toner is supplied. This is considered to be due to the action of being pushed out by the toner to be easily replaced with the toner.

“After the accumulated full-speed drive time recorded in the full-speed drive time recording unit reaches a predetermined time T1, the deceleration drive instruction unit instructs the toner supply rotary unit drive unit to change the toner supply rotary unit. “Time T1” in the case of “decelerated driving at the decelerating rotational speed for a predetermined time T2” means that when the toner supply rotator is continuously driven at full speed beyond the time T1, foaming of the layer including the surface of the toner supply rotator is performed. This is the time when the cell is clogged with an unacceptable amount of impurities such as agglomerates that cause image noise, and is a time that can be determined from experience and experimentation.

  “Time T2” means that if the toner supply rotator is driven at a reduced speed for the time T2, a desired amount of impurities such as agglomerates clogged in the foam cell of the layer including the surface of the toner supply rotator is suppressed from the cell (suppressing image noise This is the time that can be discharged), and this is also the time determined from experience and experimentation.

  Toner supply rotation for discharging impurities based on the instruction of the deceleration drive instructing unit from the viewpoint of clogging of impurities into the foam cell of the layer including the surface of the toner supply rotating body, and the degree of discharge of impurities from the cell Assuming that the toner supply rotator can be restored to the full speed drive time during the unit time of the deceleration driving of the body and can be restored to the previous state by β time, this β is expressed here as “restoration coefficient β ".

Then, when the toner supply rotator is driven to decelerate for a time T2 under the instruction of the deceleration drive instructing unit, the toner supply rotator is restored to the state T2 · β hours before T2 is multiplied by β.
From the viewpoint of clogging of impurities, the toner supply rotating body does not need to return to a state before the time T1, and therefore the time T2 is in a range satisfying the condition of [T1-T2 · β] ≧ 0. be able to.

That is, after the cumulative full speed drive time recorded in the full speed drive time recording section reaches a predetermined time T1, the deceleration drive instruction section instructs the toner supply rotary body drive section to provide the toner supply rotary body. The predetermined time T2 during which the vehicle is decelerated at the decelerated rotation speed is recorded in the full-speed drive time recording unit by the time T2 · β calculated by multiplying the time T2 by a predetermined restoration coefficient β. It can be set to a time equal to or less than a predetermined cumulative full speed driving time T1.
More preferably, the time T2 is a time satisfying [T1-T2 · β] = 0.

The full-speed driving time recording unit predetermines per unit deceleration driving time as the deceleration driving time T3 when the toner supply rotating body is driven to decelerate at a deceleration rotational speed without being directed by the deceleration driving instruction unit. The time after subtraction obtained by subtracting the time T3 · α multiplied by the restoration coefficient α from the accumulated full speed drive time t already recorded in the full speed drive time recording unit may be held as the full speed drive time.
This is because impurities are easily discharged from the toner supply rotating body even in the deceleration driving not based on the instruction by the deceleration driving instruction unit.

  Here, the “restoration coefficient α” is as follows. That is, in terms of the degree of clogging and discharging of impurities in the foam cell of the layer including the surface of the toner supply rotating body, the unit time for deceleration driving of the toner supply rotating body when not instructed by the deceleration driving instruction section Assuming that the toner supply rotator can be restored to the previous state by the full-speed driving time during this period, α can be referred to herein as “restoration coefficient α”.

  Assume that the toner supply rotator is driven to decelerate for a time T3 without being instructed by the decelerating drive instructing unit as in printing on thick paper. Then, the toner supply rotator is restored to the state before T3 · α time obtained by converting T3 by α in terms of the full speed driving time.

  From the viewpoint of clogging of impurities, the toner supply rotator does not need to return to a state prior to the current accumulated full speed drive time t already recorded in the full speed drive time recording section. The time [current cumulative full speed drive time t−T3 · α] ≧ 0 can be satisfied.

  In other words, the full-speed drive time recording unit only calculates the post-subtraction time to the cumulative full-speed drive when the post-subtraction time obtained by subtracting the time T3 · α from the recorded cumulative full-speed drive time t is 0 or more. Can be held as time.

  Note that the full speed drive time and the deceleration drive time may be counted by the time itself, but may be counted by other methods. For example, since the time required for printing on a recording medium of known size at full speed drive is known in advance, the accumulated full speed drive time may be obtained by counting the number of printed sheets at full speed drive. Further, since the time required for printing on one recording medium of known size by deceleration driving is also known, the cumulative deceleration driving time may also be obtained by counting the number of printed sheets by deceleration driving.

  When the cumulative full speed drive time recorded in the full speed drive time recording section reaches a predetermined time T1, the deceleration drive instruction section instructs the toner supply rotary body drive section to decelerate the toner supply rotary body. The timing for decelerating driving at the rotation speed is not limited to this, but an example of non-image formation that does not directly affect image formation can be given.

  Here, “when non-image is formed” means a time other than “when image is formed” when an image for transferring and outputting a toner image on a recording medium is formed. For example, the deceleration drive instruction unit is as described above. Instructing the toner supply rotator drive unit to drive the toner supply rotator at a reduced rotational speed, the timing when the image formation is interrupted and printing is interrupted (interruption of printing) is given. be able to.

  In addition, for example, a sequence that is executed periodically after the original printing operation is stopped, such as cleaning of an intermediate transfer belt or a photosensitive member, can be used. When the toner supply rotating body is driven to decelerate during such a sequence, the sequence drive time is calculated in advance, and if the value converted to the full speed drive time exceeds a predetermined threshold, the sequence is executed. By performing the half-speed driving, the printing interruption time can be reduced.

  The developing device may include a developing bias power source that applies a developing bias in which an alternating current component is superimposed on a direct current component to the toner carrying rotating body in developing the electrostatic latent image on the latent electrostatic image bearing member.

  When this type of development bias power source is provided, the development bias power source is configured to perform the deceleration drive instruction in order to smoothly discharge impurities such as aggregates from the foam cell of the layer including the surface of the toner supply rotating body. An alternating current component having a higher peak-to-peak voltage than that at the time of image formation may be used as the alternating current component during the deceleration driving of the toner supply rotator based on the instruction of the unit.

  The developing bias power source may use an AC component having a higher frequency than that during image formation as the AC component during the deceleration driving of the toner supply rotating body based on an instruction from the deceleration driving instruction unit.

  As described above, according to the present invention, an electrostatic latent image can be formed on an electrostatic latent image carrier, and the electrostatic latent image can be developed by a developing device to form a toner image. At least one developing device can A toner carrying rotator for applying toner to the electrostatic latent image on the corresponding electrostatic latent image carrier, and supplying the toner to the toner carrying rotator and remaining on the toner carrying rotator without being consumed by development. A toner supply rotator that scrapes off the toner, and a layer thickness of the toner that is supplied from the toner supply rotator to the toner carrying rotator and conveyed to the development area of the electrostatic latent image on the toner carrying rotator is regulated. And a toner regulating member in contact with the toner carrying rotator, wherein the toner supply rotator is a developing device of a non-magnetic one-component developing system in which a layer including the surface is formed of an elastic foam material. A forming device, wherein at least one of said In a magnetic one-component development type developing device, impurities such as developer aggregates entering the foamed cells in the layer including the surface of the toner supply rotating body and aggregates resulting from toner external additives are discharged at a predetermined timing. Therefore, it is possible to provide an image forming apparatus that can suppress the occurrence of image noise due to impurities in an image developed and formed by the developing apparatus, and can form a good image as the entire image forming apparatus. .

1 is a diagram schematically illustrating a configuration of an example of an image forming apparatus according to the present invention. FIG. 2 is a diagram showing an outline of a sectional structure of a developing device in the image forming apparatus of FIG. 1. FIG. 3 is a diagram schematically showing the developing device shown in FIG. 2 as viewed from the right side in FIG. 2, but the developing roller and the supply roller are only indicated by their positions with broken lines. FIG. 2 is a block diagram illustrating an outline of a control circuit of the image forming apparatus in FIG. 1. 6 is a flowchart showing an example of aggregate discharge control from a toner supply roller of a developing device by a control unit in the control circuit shown in FIG. 4. 6 is a flowchart showing another example of the aggregate discharge control from the toner supply roller of the developing device by the control unit in the control circuit shown in FIG. 10 is a flowchart showing still another example of the aggregate discharge control from the toner supply roller of the developing device by the control unit in the control circuit shown in FIG. 4.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 schematically shows the configuration of an example 100 of an image forming apparatus according to the present invention. The image forming apparatus 100 is a tandem type full color printer.

  The printer 100 includes an endless intermediate transfer belt 7 wound around a driving roller 71 and a roller 72 facing the driving roller 71. The transfer belt 7 is rotated in the counterclockwise direction (arrow direction in the figure) CCW by a driving roller 71 driven by a belt driving unit (not shown).

  A cleaning device 73 that cleans secondary transfer residual toner and the like on the transfer belt 7 faces the roller 72, and a secondary transfer roller 8 faces the drive roller 71.

  The secondary transfer roller 8 is pressed against a portion of the intermediate transfer belt 7 supported by the driving roller 71 by a pressing unit (not shown), forms a nip portion with the intermediate transfer belt 7, and rotates the intermediate transfer belt 7. It can be rotated by being driven or driven or driven by the movement of the recording medium S fed into the nip as will be described later. A secondary transfer bias can be applied to the secondary transfer roller 8 from a power supply (not shown).

  A fixing device 9 is disposed above the intermediate transfer belt 7 and the secondary transfer roller 8, a timing roller pair 11 is disposed below, and a recording medium S such as recording paper is accommodated below the fixing device 9. The recording medium storage cassette 10 is disposed.

The fixing device 9 includes a fixing heating roller having a heat source such as a halogen lamp heater and a pressure roller pressed against the fixing heating roller.
The recording medium S accommodated in the recording medium accommodating cassette 10 can be pulled out one by one by the medium supply roller 101 and supplied to the timing roller pair 11.

  Between the rollers 71 and 72 around which the intermediate transfer belt 7 is wound, the yellow image forming unit Y, the magenta image forming unit M, and the cyan image forming unit C are arranged along the transfer belt 7 from the roller 72 toward the roller 71. And the black image forming portion K are arranged in this order.

  Each of the image forming units Y, M, C, and K includes a drum-type photosensitive member 1 as an electrostatic latent image carrier, and a charger 2, an exposure device 3, a developing device 4 and the like around the photosensitive member. The cleaning devices 5 are arranged in this order.

  A primary transfer roller 6 is disposed opposite to the photoreceptor 1 of each image forming unit with a belt 7 therebetween. The primary transfer roller 6 is pressed in the direction of the photosensitive member 1 by a pressing unit (not shown), contacts the belt 7 and rotates in a driven manner, and can bring the belt 7 into contact with the photosensitive member 1.

  A primary transfer bias for primary transfer of the toner image formed on the photoreceptor 1 to the belt 7 can be applied to the primary transfer roller 6 from a power supply (not shown).

  The exposure device 3 can perform image exposure by dot (point) exposure on the photosensitive member 1 by blinking of a laser beam in accordance with image information provided from a personal computer (not shown), an image reading device, or the like.

  The photoconductor 1 in each image forming unit is a negatively chargeable photoconductor here, and can be driven to rotate clockwise in the drawing by a photoconductor drive motor (not shown).

  The charger 2 in each image forming unit is charged with a charging voltage from a power supply (not shown) at a predetermined timing, so that the surface of the photoreceptor 1 can be uniformly charged to a predetermined potential. The charger 2 is a non-contact type using corona discharge in this example, but may be a charging roller or the like.

  In this example, the developing device 4 in each image forming unit applies a developing bias to an electrostatic latent image formed on the photoreceptor 1 using a one-component developer mainly composed of toner from a power supply (not shown). The developer carrying rotating body (hereinafter referred to as “developing roller”) 41 (see FIG. 2) in the form of a roller can be used for reversal development. The developing device 4 will be further described later.

  A control unit Cont in the control circuit of the printer 100 schematically shown in the block diagram of FIG. 4 controls the operation of the printer 100. Each of the image forming units Y, M, C, and K, each unit of the printer 100 such as a recording medium conveyance mechanism, and the fixing device 9 operates based on an instruction from the control unit Cont.

An operation panel PA is also connected to the control unit Cont (see FIG. 4), and an image forming mode, the number of images formed, and the like can be set on this panel.
The control unit Cont also includes a full speed drive time recording unit, a deceleration drive instruction unit, and the like. These will be discussed further later.

According to this printer, an image can be formed using one or more of Y, M, C, and K image forming units.
Taking a case where a full color image is formed using all of the image forming portions Y, M, C, and K as an example, first, a yellow toner image is formed in the yellow image forming portion Y, and this is formed on the transfer belt 7 as a primary. Transcript.

  That is, in the yellow image forming portion Y, the photosensitive member 1 is rotationally driven in the clockwise direction in the drawing, and the surface is uniformly charged to a predetermined potential by the charger 2, and the exposure device 3 corresponds to the yellow image in the charged area. Thus, an electrostatic latent image corresponding to the yellow image is formed on the photoreceptor 1. This electrostatic latent image is developed by a developing roller 41 to which a developing bias of the developing device 4 having yellow toner is applied, and becomes a visible yellow toner image. The yellow toner image is primarily transferred onto the transfer belt 7 by the primary transfer roller 6. At this time, a primary transfer bias is applied to the primary transfer roller 6 from a power supply (not shown).

  Similarly, a magenta toner image is formed in the magenta image forming unit M and transferred to the transfer belt 7. A cyan toner image is formed in the cyan image forming unit C and transferred to the transfer belt 7. In the black image forming unit K. A black toner image is formed and transferred to the transfer belt 7.

Yellow, magenta, cyan, and black toner images are formed at a timing when these toner images are transferred onto the intermediate transfer belt 7 in an overlapping manner.
Thus, the multiple toner image formed on the transfer belt 7 moves toward the secondary transfer roller 8 by the rotation of the transfer belt 7.

  On the other hand, the recording medium S is pulled out from the recording medium accommodation cassette 10 by the medium supply roller 101 and is supplied to the timing roller pair 11 and is on standby.

  Thus, the recording medium S waiting at the timing roller pair 11 is supplied to the nip portion between the transfer belt 7 and the secondary transfer roller 8 in accordance with the multiple toner image sent by the intermediate transfer belt 7. . The multiple toner image is secondarily transferred onto the recording medium S by a secondary transfer roller 8 to which a secondary transfer bias is applied from a power supply (not shown).

  Thereafter, the recording medium S is passed through the fixing device 9 where the multiple toner images are fixed on the recording medium S under heat and pressure. The recording medium S is continuously discharged to the discharge tray 13 by the discharge roller pair 12.

  In the primary transfer of the toner image to the belt 7, transfer residual toner or the like remaining on the photoreceptor 1 is cleaned by the cleaning device 5, and secondary transfer residual toner or the like remaining on the belt 7 by the secondary transfer is cleaned by the cleaning device 73. It is cleaned with. Each of these cleaned and removed toners is sent to a waste container by a conveying means (not shown).

  Although the image is formed as described above, the developing device 4 will be further described. The developing device 4 is shown in FIGS.

  FIG. 2 schematically shows a cross-sectional structure of the developing device 4. FIG. 3 schematically shows the developing device 4 as viewed from the right in FIG. 2, but the developing roller 41 and the supply roller 42 are only indicated by their positions with broken lines.

The developing device 4 includes a developing roller 41 that is an example of a toner carrying rotator and a supply roller 42 that is an example of a toner supply rotator that supplies developer to the developing roller 41.
The developing roller 41 is provided with an elastic layer made of a thermoplastic elastomer or rubber on a conductive shutter, and a surface coat layer having a higher hardness than the elastic layer on the surface thereof.
The supply roller 42 is provided with a conductive foam layer having elasticity on a conductive shaft. The roller 42 includes a single cell (not an expanded cell connected to another expanded cell but an independent expanded cell) in a layer including the surface.

  The developing device 4 also includes a plate-like toner supply auxiliary member 420 that is disposed in contact with the supply roller 42 from below, and further, a first transport rotating body that supplies the developer to the supply roller 42 side while stirring. 46 and a second rotary carrier 47 are also provided. Here, each of the first and second rotary transport bodies is a screw transport member in which screw blades (spiral blades) are provided around the rotation shaft.

  The developing roller 41, the supply roller 42, and the first and second screw conveying members 46 and 47 are accommodated in the developing device housing 40, and are rotatably supported by the housing. A part of the developing roller 41 protrudes outside the housing 40 so as to face the photoreceptor 1 when the developing device 4 is mounted on the image forming apparatus 100. The conveying members 46 and 47 are accommodated in the developing device housing 40.

  In the housing 40, there is formed a buffer portion 43 that holds a developer (toner T in this example) (see FIG. 4) for development and faces the supply roller 42 and the development roller 41.

  The first screw conveying member 46 is disposed in the buffer unit 43 above the supply roller 42 and at a position behind the roller 42. The second screw conveying member 47 is disposed above the first screw conveying member 46 and above the supply roller 42 with a plate-like partition member 48 therebetween.

  The first screw conveying member 46 is arranged in parallel with the developing roller 41, and the second screw conveying member 47 is arranged in parallel with the first screw conveying member 46 with the partition member 48 in between.

  As shown in the control circuit of FIG. 4, each rotating member in the developing device 4 is rotationally driven by a developing device drive unit D that uses a developing motor (not shown) as a drive source. A predetermined developing bias is applied to the developing roller 41 of the developing device 4 from the developing bias power source PW when developing the electrostatic latent image on the photoreceptor 1 corresponding to the roller.

  The first screw conveying member 46 is rotationally driven by the driving unit D, so that the developer can be conveyed in the direction of the rotation axis from the right side to the left side in FIG. 3, and the second screw conveying member 47 is driven by the driving unit D. By being driven to rotate, the developer can be conveyed in the direction of the rotation axis from the left side to the right side in FIG.

  As the first and second screw conveying members 46 and 47 are driven to rotate as described above, the developer is developed on the right side in FIG. The developer feeding side end (developer feeding side end) is conveyed to the left developer sending side end (developer sending side end), and the left side end of the partition member 48 from the developer sending side end. Through the opening (second opening) 482 of the second conveying member 47, the second conveying member 47 moves upward to the developer feeding side end, and is further conveyed by the second conveying member 47 toward the developer sending side end. From the delivery side end portion, the partition member 48 passes through the opening portion (first opening portion) 481 at the right end portion of the partition member 48 and drops and moves to the developer feeding side end portion of the first conveying member 46 while being assisted by gravity. . In this way, the developer is supplied to the supply roller 42 and, consequently, the developing roller 41 side from the first transport member 46 while being stirred and circulated by the first and second transport members 46 and 47.

  The developing roller 41 and the supply roller 42 are driven to rotate counterclockwise in FIG. Therefore, it can be said that the drive unit D is a drive unit that rotationally drives the supply roller 42. In the nip portion where the rollers 41 and 42 face each other, both roller surfaces move in opposite directions. As a result, the supply roller 42 scrapes off the developer that returns to the developing device housing 40 without being consumed by the development from the development roller 41 and supplies the developer to the development roller 41 anew.

  When the developer (toner) is supplied from the roller 42 to the roller 41, the roller 42 slides on the toner supply auxiliary member 420, so that the roller 42 can reliably hold and transport the toner.

  When the developer thus supplied passes through the blade-shaped toner regulating member 44 that is in contact with the developing roller 41, the amount of toner is properly regulated, and accordingly, the developer is conveyed to the developing region facing the photoreceptor 1. The toner layer thickness is appropriately regulated and charged with it, and is used for developing the electrostatic latent image on the photoreceptor 1 in the development region.

  The developer that has not been consumed by the development returns to the case 40 as the developing roller 41 rotates. At this time, the developer is neutralized by a neutralization member 45 to which a neutralization bias is applied from a neutralization power supply (not shown) in order to facilitate scraping of the development roller 41 by the supply roller 42.

  The first and second screw conveying members 46 and 47 are arranged in the direction of the rotation axis of the developing roller 41 at the developer feeding side end of the conveying member 46 and the developer feeding side end of the conveying member 47 located above the first screw conveying members 46 and 47. The developer extends to the outside of the developing roller 41, and a developer reservoir 49 is continuously provided above the extended portion of the second conveying member 47.

In FIG. 3, for example, a transparent resin (for example, polystyrene) for detecting the amount of developer (here, the upper surface position of the developer in the reservoir) on each of the front and back walls facing each other of the developer reservoir 49. ), And a developer amount detection device TS is provided for these windows.
When the developer reservoir 49 is formed of a transparent material such as transparent polystyrene resin, a part of the developer reservoir 49 can be used as a detection window.

  In this example, the developer amount detection device TS includes an optical sensor having a light emitting element and a light receiving element. The light emitting element faces one detection window dw from the outside, and the light receiving element faces the other detection window dw from the outside. When the light receiving element receives a predetermined amount of light from the light emitting element, it is determined that the amount of developer in the developing device 4 is insufficient, and the light from the light emitting element is blocked by the developer and the light receiving element receives a predetermined amount of light. If not, it is determined that the developer amount is sufficient. The developer reservoir 49 is provided with a toner supply port 490 to which the toner bottle portion of the toner supply unit TB including the toner bottle can be detachably mounted. When the detecting device TS detects that the developer amount is insufficient, the toner can be supplied from the toner supply unit TB.

  According to the control unit Cont, as will be described in the following embodiments, the developing device 4 of each image forming unit discharges impurities such as aggregates entering the foaming cells of the layer including the surface of the toner supply roller 42. Can be controlled.

For this purpose, the control unit Cont includes a full speed driving time recording unit, a deceleration driving instruction unit, and the like as described above.
The full-speed drive time recording unit cumulatively records the full-speed drive time according to the full-speed rotation speed of the toner supply roller 42 of the developing device 4 when forming an image on plain paper or the like. In this example, the full speed driving time of the developing motor of the developing device driving unit D is adopted as the full speed driving time.

The decelerating drive instructing unit is a developing unit that is also a driving unit of the toner supply roller 42 after the accumulated full-speed driving time (developing motor accumulated full-speed driving time) recorded in the full-speed driving time recording unit reaches a predetermined time T1. The apparatus driving unit D (see FIG. 4) is instructed to drive the toner supply roller 42 at a half time rotational speed that is half the full speed rotational speed for a predetermined time T2.
In this example, the half-speed driving time of the developing motor is employed as the half-speed driving time in this case.

  In the following example, in printing at a normal system speed (185 mm / sec) (full speed driving), full color printing is performed on A4 size recording paper with a predetermined pattern using the image forming units Y to K.

  The surface of the photosensitive member 1 of each image forming unit is uniformly charged to approximately −450 [V] by a charger 2, and image exposure is performed from the exposure device 3 in the charged area to form an electrostatic latent image. In the developing device 4, the developing bias power source PW (see FIG. 4) supplies the developing roller 41 with a DC bias of −320 [V] and an AC baice (frequency 2 kHz, duty 30%) with a peak-to-peak voltage of 1200 [V]. Apply superimposed.

The conductive elastic foam material that forms a layer including the roller surface and is provided around the conductive shaft of the toner supply roller 42 is an elastic foamed polyurethane (Inoac Corporation).
Exroth-BB) with conductive carbon added to make it conductive.

The conductive elastic foam material forming the layer including the roller surface of the supply roller 42 may be made by adding conductive carbon to elastic foam polyurethane (Inoac Corporation EMM-C Co., Ltd.). Can be adopted.
The Exroth-BB foam cell is a single-cell type cell, and the EMM-C foam cell is an open-cell type cell.

<Example 1> (see FIG. 5)
As shown in the flowchart of FIG. 5, when printing is in progress, the developing motor is driven at full speed (therefore, the toner supply roller 42 is also driven at full speed and at full speed) (step S1). In step S2, the developing motor full speed driving time for printing one sheet of recording paper is added as the accumulated full speed driving time. Thereafter, it is determined whether or not the development motor accumulated full speed drive time has reached a predetermined time T1 (step S3). In this example, the time T1 is a time corresponding to 100 sheets printing by full speed drive printing.

  After reaching the time T1 (in other words, after printing 100 sheets), the development motor drive is switched to the half speed drive (step S4), and the development motor accumulated full speed drive time remaining in the full speed drive time recording unit is determined. Whether or not the remaining developing motor accumulated full speed drive time becomes negative that is smaller than 0 is determined (step S6), and the subtraction result does not become negative (in this example, 0). Until the development motor accumulated full speed driving time is subtracted (steps S5 and S6).

  Here, when image printing is performed for one sheet by half-speed driving, the supply roller 42 restores 20 sheets of printing by full-speed driving in terms of clogging of impurities such as aggregates in the foamed cell. . Therefore, as the half-speed driving time for discharging aggregates and the like from the supply roller 42, a time corresponding to the number of printed sheets by half-speed driving is employed. As a result, the supply roller 42 is restored to the previous state of 100 image prints by full speed driving.

  In this way, impurities such as developer aggregates and aggregates caused by the toner additive are discharged from the foam cells of the layer including the surface of the supply roller 42, and an image in which image noise is suppressed can be formed accordingly. .

  The development motor accumulated full speed driving time T1 corresponding to 100 sheets of full speed driving printing, which is the above-described half speed driving switching timing, is set to another value, for example, the developing motor accumulated full speed driving time corresponding to 200 sheets of full speed driving printing. The half-speed driving time for discharging impurities can be set to a time corresponding to 10 printed sheets by half-speed driving, and the numerical value can be changed by maintaining a proportional relationship.

  In addition, when INOAC CORPORATION EMM-C is used as the elastic foam material that forms the layer including the surface of the supply roller 42, 5 half-speed drive times can be used for 500 full-speed drive times. Thus, the numerical value can be changed according to the type of the elastic foam material to be used.

<Example 2> (see FIG. 6)
The full speed drive time recording unit is driven at half speed at a half speed rotation speed that is half the full speed without the supply roller 42 being instructed by the deceleration drive instruction unit as in the case of printing on thick paper such as an envelope. In this case, the accumulated full-speed drive already recorded in the full-speed drive time recording unit is obtained by multiplying the accumulated half-speed drive time T3 by a restoration factor α determined in advance per unit deceleration drive time. The time after subtraction subtracted from the time t may be held as the full speed driving time. The second embodiment is an example of control in the case where the full speed driving time recording unit is in such a case. The second embodiment is an example in which the developing motor rotation speed is set to two types of full-speed rotation speed and half-speed rotation speed.

In the second embodiment, as shown in the flowchart of FIG. 6, the control in which steps S <b> 7 and S <b> 8 are further added to the flowchart showing the control of the first embodiment is performed.
That is, when the developing motor is not driven at full speed in the printing operation (“N0” in step S1, and therefore half speed driving), subtraction is made from the developing motor accumulated full speed driving time currently recorded in the full speed driving time recording section. It is determined whether or not it is possible (whether the remaining developing motor accumulated full speed drive time becomes negative less than 0 by subtraction) (step S7), and within a range where the subtraction result does not become negative (until 0 in this example). ) The development motor accumulated full speed drive time is subtracted (steps S7 and S8).

  As a result, the same control as that in the first embodiment is performed by subtracting the discharge amount from the supply roller 42 of impurities such as agglomerates by half-speed driving of the developing motor that does not depend on the instruction from the deceleration driving instruction unit.

  For example, when one sheet of thick paper printing is performed in which half-speed driving is performed after 50 sheets are printed with full-speed driving, the time corresponding to 20 sheets of full-speed driving is equivalent to 50 sheets currently recorded in the full-speed driving time recording unit. By subtracting from the total developing motor accumulated full speed driving time, the developing motor accumulated full speed driving time is made equivalent to 30 full speed driving times.

<Example 3> (see FIG. 7)
In the third embodiment, as shown in the flowchart of FIG. 7, the control in which step S <b> 30 is further added to the flowchart showing the control of the first embodiment is performed.
That is, if it is determined in step S3 that the development motor accumulated full speed driving time has reached a predetermined time, the printing operation of the printer 100 is interrupted (step S30), and the state at the time of non-image formation is generated in this way. Steps S4, S5, and S6 are executed.

  For example, when 200 sheets are printed at full speed, image formation is temporarily stopped after 100 sheets have been printed, and after steps S4, S5, and S6 are executed (here, half speed driving is performed for a time corresponding to five sheets). The remaining 100 sheets are printed at full speed.

  In order to more smoothly discharge impurities such as agglomerates from the toner supply roller 42, a developing bias is applied when the supply roller 42 is decelerated by the decelerating drive instruction unit of the control unit Cont as in the following fourth and fifth embodiments. You may adjust.

<Example 4>
In the developing bias power source PW of the developing device 4, the peak-to-peak voltage of the AC component of the developing bias is set to 1400 [V] with respect to the normal 1200 [V].
<Example 5>
In the developing bias power source PW of the developing device 4, the frequency of the alternating current component of the developing bias is set to 3 kHz with respect to the normal 2 kHz.

  By adjusting the developing bias as described above, the aggregate can be efficiently discharged from the supply roller 42.

  The image forming apparatus described with reference to FIG. 1 is a tandem type full-color printer 100. However, the present invention can also be applied to a monochrome image forming apparatus, and also to other types of multicolor image forming apparatuses. it can. Further, in an image forming apparatus having a plurality of developing devices, the present invention may be applied only to a smaller number of developing devices (for example, developing devices used for monochrome printing) than the total number of the developing devices.

  The present invention relates to an image forming apparatus using a developing device of a non-magnetic one-component developing system, and a developer aggregation in which a surface layer of the developing device enters a surface layer foam cell of a toner supply rotating body formed of an elastic foam material layer The present invention can be used to provide an image forming apparatus that can discharge impurities such as agglomerates and aggregates caused by toner external additives at a predetermined timing and can form an image in which image noise is suppressed accordingly.

DESCRIPTION OF SYMBOLS 100 Printer Y Yellow image formation part M Magenta image formation part C Cyan image formation part K Black image formation part 1 Photoconductor 2 Charger 3 Image exposure apparatus 4 Development apparatus 40 Development apparatus housing 41 Development roller 42 Developer supply roller 43 Buffer part 44 Developer regulating member 45 Neutralizing member 46 First screw conveying member 47 Second screw conveying member 48 Partition member 481, 482 Developer flow opening 49 of partition member Developer reservoir 490 Toner replenishment port TS Developer amount detection device dw detection window TB toner replenishing device D developing device driving unit PW developing bias power source 5 cleaning device 6 primary transfer roller 7 intermediate transfer belt 71 driving roller 72 opposing roller 73 cleaning device 8 secondary transfer roller 9 fixing device 10 recording medium supply cassette 101 Recording medium supply roller 11 Thailand Mining roller pair 12 Recording medium discharge roller pair 13 Recording medium discharge tray S Recording medium 51, 52 Developer transport amount stabilizing member 601 Film holding member 602 Flexible film 61, 62 Developer transport amount stabilizing member 480 Developer mixing Stirring device 483 Small partitioning members 482a, 482b Openings 460, 470 formed in a split manner Spiral blade T Developer control part Cont

Claims (7)

An electrostatic latent image can be formed on the electrostatic latent image carrier, and the electrostatic latent image can be developed with a developing device to form a toner image. At least one developing device can be mounted on the corresponding electrostatic latent image carrier. A toner carrying rotator for applying toner to the electrostatic latent image, a toner supply rotator for supplying toner to the toner carrying rotator and scraping off toner remaining on the toner carrying rotator without being consumed in development; The toner is supplied to the toner carrying rotator from the toner supply rotator and is brought into contact with the toner carrying rotator for regulating the layer thickness of the toner on the toner carrying rotator which is transported to the development area of the electrostatic latent image. An image forming apparatus that is a non-magnetic one-component developing type developing device in which a layer including a surface is formed of an elastic foam material.
About at least one developing device of the non-magnetic one-component developing system,
A toner supply rotator driving unit capable of driving the toner supply rotator at a predetermined full-speed rotation speed or a predetermined decelerated rotation speed slower than the full-speed rotation speed;
A full-speed drive time recording unit for accumulating and recording the full-speed drive time according to the full-speed rotation speed of the toner supply rotator;
After the accumulated full speed drive time recorded in the full speed drive time recording section reaches a predetermined time T1, the toner supply rotary body is instructed to the toner supply rotary body by a predetermined time T2, the deceleration. An image forming apparatus comprising: a decelerating drive instruction unit that decelerates and drives at a rotational speed.   The full-speed drive time recording unit, when the toner supply rotator is driven to decelerate at a decelerating rotational speed without being instructed by the decelerating drive instructing unit, includes a unit time for the unit decelerating drive time in the accumulated time T3 of the decelerating drive. 2. The time after subtraction obtained by subtracting a time T3 · α multiplied by a predetermined restoration coefficient α from the accumulated full speed drive time t recorded in the full speed drive time recording section is held as the accumulated full speed drive time. Image forming apparatus.   The full-speed drive time recording unit holds the post-subtraction time as the accumulated full-speed drive time only when the post-subtraction time obtained by subtracting the time T3 · α from the recorded accumulated full-speed drive time t is 0 or more. The image forming apparatus according to claim 2.   After the cumulative full speed drive time recorded in the full speed drive time recording section reaches a predetermined time T1, the deceleration drive instruction section instructs the toner supply rotary body drive section to set the toner supply rotary body to the The predetermined time T2 for decelerating driving at a reduced rotational speed is the predetermined time T2 · β calculated by multiplying the time T2 by a predetermined restoration coefficient β recorded in the full-speed driving time recording unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is a time that is equal to or shorter than the accumulated full speed driving time T <b> 1.   After the cumulative full speed drive time recorded in the full speed drive time recording section reaches a predetermined time T1, the deceleration drive instruction section instructs the toner supply rotary body drive section to set the toner supply rotary body to the 5. The image forming apparatus according to claim 1, wherein the timing of decelerating driving at the decelerating rotational speed is during non-image formation.   A developing bias power source for applying a developing bias in which an alternating current component is superimposed on a direct current component to the toner carrying rotor in developing the electrostatic latent image on the electrostatic latent image bearing member; The image forming apparatus according to claim 1, wherein an AC component having a higher peak-to-peak voltage than that during image formation is used as the AC component during the deceleration driving of the toner supply rotating body based on an instruction from a deceleration driving instruction unit.   A developing bias power source for applying a developing bias in which an alternating current component is superimposed on a direct current component to the toner carrying rotor in developing the electrostatic latent image on the electrostatic latent image bearing member; The image forming apparatus according to claim 1, wherein an AC component having a higher frequency than that at the time of image formation is used as the AC component during the deceleration driving of the toner supply rotating body based on an instruction from a deceleration driving instruction unit.

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