JP4590935B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to a cleaning device that collects transfer residual toner generated by transfer when transferring a toner image obtained by developing an electrostatic latent image formed on an image carrier onto a recording medium via an intermediate transfer member, and an image. The present invention relates to a forming apparatus.

  Conventionally, in an image forming apparatus such as a full-color printer, a photoconductor as an image carrier is provided for each of yellow (Y), magenta (M), black (K), and cyan (C), and Y is provided on each photoconductor. , M, K, and C, an electrostatic latent image corresponding to each color is formed, each color toner is attached to the electrostatic latent image of each color from a developing device as a developing means, and development is performed. A full color toner image formed by superimposing the toner image on the intermediate transfer member is transferred to a recording medium. During the transfer to the recording medium, since there is residual toner that remains untransferred on the photosensitive member and the intermediate transfer member, the image forming apparatus collects the residual toner by a cleaning device as a residual toner collecting unit. Yes.

  In recent years, these image forming apparatuses are required to be miniaturized, and cleaning apparatuses are also miniaturized. This miniaturized cleaning device includes a cleaning roll as a transfer residual toner recovery mechanism that recovers transfer residual toner, and a temporary storage chamber that stores the recovered transfer residual toner. Some transfer residual toner stored in the storage chamber is transported by a fixed amount by an auger serving as transport means provided in the temporary storage chamber, and is collected and held in a recovery container. However, when the size of the cleaning device is reduced, the capacity of the temporary storage chamber is reduced, and the amount of toner that can be collected at one time is reduced, and the transfer residual toner may not be sufficiently collected. For this reason, in Patent Document 1, a solid toner image having the darkest image density is formed with the amount of toner that can be collected by the cleaning device. For example, a conveyance failure (so-called jam) occurs on a recording medium such as paper. It is disclosed that the amount of toner is not less than the amount of toner when the solid toner image remains without being transferred. As a result, even when all the solid toner images remain and become transfer residual toner, all can be collected by the cleaning device.

On the other hand, some image forming apparatuses perform development by loading a two-component developer composed of toner and carrier into a developing device in order to form a high-quality image. In the developing device using the two-component developer, development is performed by charging the toner and the carrier by stirring, and the toner concentration to be adhered to the photoreceptor is adjusted. The toner is discharged and collected by the cleaning device. Here, the amount of toner discharged to adjust the toner density may be larger than the amount of toner adhering to the photoconductor as the solid toner image, and the cleaning device adheres to the photoconductor as the solid toner image. Toner more than the toner amount may be collected.
Japanese Patent Laid-Open No. 11-184244

The present invention aims to provide an image forming equipment which can properly maintain the toner density of each developing unit.

According to the first aspect of the present invention, an electrostatic latent image showing an image of each color of yellow, magenta, black, and cyan is formed on each of the plurality of image carriers based on the image data, and the plurality of image carriers are formed on the plurality of image carriers. The formed electrostatic latent image is developed by attaching each color toner from a plurality of developing means provided on each of the plurality of image carriers, and the developed toner image of each color is recorded via an intermediate transfer member. An image forming apparatus for transferring to a medium, a calculation unit that calculates a toner amount of each color attached from the plurality of developing units based on the image data, and a toner amount of each color calculated by the calculation unit A storage unit that accumulates and stores the accumulated toner amount for each color, and reads the accumulated toner amount of each color stored in the storage unit, and the other three colors other than the accumulated toner amount of the largest accumulated amount and the largest accumulated amount Each with a cumulative toner amount of The when the addition value is equal to or greater than a predetermined value, and a, a toner discharge control means performs control to perform the discharge of the toner from the developing unit in accordance with the respective difference.
Thereby, the toner density of each developing unit can be maintained appropriately.

Invention according to claim 2, in the invention of claim 1 Symbol mounting, is disposed opposite to at least one of the image bearing member or the intermediate transfer member, toner on the at least one of the image bearing member or the intermediate transfer member The toner collecting mechanism unit for collecting the toner, the toner collecting unit configured to temporarily store the collected toner, and the toner collecting mechanism unit are interlocked with the toner collecting mechanism unit and stored in the temporary storage chamber. A conveying unit configured to convey the toner in a predetermined direction; and a collection container that is provided in a conveying direction by the conveying unit to finally collect and hold the toner, and the toner discharge control unit The amount of toner discharged by each developing unit is 1/3 or less of the capacity of the temporary storage chamber.

According to the second aspect of the present invention, when the toner amount D discharged from the developing unit is 1/3 or less of the capacity of the temporary storage chamber, the toner is recovered by the transfer residual toner recovery mechanism and stored in the temporary storage chamber. The amount of transfer residual toner is 1/3 or less of the capacity. In the transport unit, if the stored transfer residual toner is 1/3 or less of the capacity, the load applied to the transport unit is small, and therefore the driving force necessary to drive the transport unit can be kept within a predetermined range. it can. Thereby, damage to the drive system can be prevented.

The invention of claim 3 is the invention of claim 2, wherein, prior Quito toner collecting mechanism is based on the electrostatic force generated by the predetermined voltage is applied to deposit the door toner on the peripheral surface and cleaning roll in contact with the peripheral surface of the cleaning roller, characterized in that it is a blade and, in configuration to guide to the temporary storage chamber by scraping the belt toner adhered.

According to the invention described in claim 3, the cleaning roll by attaching the door toner an electrostatic force due to the predetermined voltage is applied, the blade scrape the door toner in contact with the cleaning roll, to the temporary storage chamber I am guiding you. The blade scrapes the belt toner adhering to the cleaning roller, but since a state in which the bets toner slightly spaced from the cleaning roll in the portion that is attached, wear of the cleaning roll and blade is reduced, cleaning The replacement time of the rolls and blades can be extended.

As described above, according to the present invention has the excellent effect that can provide an image forming equipment which can properly maintain the toner density of each developing unit.

  FIG. 1 shows an outline of an image forming apparatus 10 according to an embodiment of the present invention. The image forming apparatus 10 includes an image forming apparatus main body 12, and a paper feeding unit 14 is provided below the image forming apparatus main body 12.

  The paper feed unit 14 includes a paper tray 22 on which paper is stacked and a paper feed roll 24 that sends out the paper from the paper tray 22, and the paper delivered by the paper feed roll 24 is transported by a transport roll. The paper passes through the paper feed path 30 through the paper 26 and 28, and is conveyed to a transfer roll 74 described later.

  After the toner image is transferred onto the paper by the transfer roll 74 and fixed by the fixing unit 32, the toner image is provided on the upper portion of the image forming apparatus main body 12 by the discharge roll 36 or the discharge roll 38 depending on the position of the switching claw 34. The paper is discharged to the first discharge tray 16 or the second discharge tray 18.

  Here, in the case of double-sided printing, after the printing of the front surface is completed in the order as described above, before the paper is completely discharged to the first discharge tray 16, the discharge roll 36 is reversed and the paper is reversed. Supplied to the line 40. The paper is then returned to the paper feed path 30 through the transport rolls 42, 44, 46, and 48, and the back side of the paper is printed. In the case of manual printing, by placing paper on the manual feed tray 20, the paper is transported from the manual feed roll 49 to the paper feed path 30 via the transport roll 48 and printed.

  Meanwhile, on the right side of FIG. 1 of the image forming apparatus 10, four developer cartridges 64 filled with developer for each color (consisting of toner and carrier) are arranged. The developer cartridge 64 is connected to developing units 60Y, 60M, 60K, and 60C, which will be described later, arranged in order from the top of FIG. 1 through a developer supply path 65, and the developer in the developer cartridge 64 is stored in the developer cartridge 64. Supplied to developing devices 60Y, 60M, 60K, and 60C.

  An exposure unit 62 is arranged on the left side of the developer cartridge 64 in FIG. 1, and the exposure unit 62 emits four laser beams L (Y), L (M), L (K), and L (C). The light is output toward the photoconductor 52 constituting the photoconductor unit 50 arranged on the left side of the exposure unit 62 in FIG.

  The exposure unit 62 has laser beams L (Y), L (M), L (K), and L (C) modulated in accordance with the colors Y, M, C, and K of the image to be formed (hereinafter collectively referred to as “collection”). A light source (not shown) for outputting laser light L), a modulation processing part (not shown) for modulating the laser light L based on an image to be formed, and the laser light L on each photoconductor 52. A polygon mirror 62A for scanning and a mirror group 62B composed of a plurality of mirrors are included.

  The photoconductor unit 50 includes four photoconductors 52 (52Y, 52M, 52K, and 52C) arranged in the vertical direction. From the top, for example, yellow (52Y), magenta (52M), black (52K), and cyan. The laser light L emitted from the light source unit and modulated by the modulation processing unit is converted into scanning light by the polygon mirror 62A, and the photoconductor 52 corresponding to each color is arranged by the mirror group 62B. Reflected in the direction and imaged on each photoconductor 52.

  As shown in FIG. 2, the photoconductor unit 50 includes a charging roll 56 and a refresh roll 54 corresponding to each photoconductor 52, and is provided so as to rotate in contact with the photoconductor 52. . The charging roll 56 applies a negative voltage (for example, −800 V) to uniformly charge the photosensitive member 52 to the negative polarity (for example, −500 V). Each of the uniformly charged photoreceptors 52 is subjected to scanning exposure with the laser beam L to form an electrostatic latent image, and toner is discharged from a magnet roll 80 provided in a developing unit 58 described later. It adheres to the surface of the photoreceptor 52. On the other hand, the refresh roll 54 discharges the photosensitive member 52 to remove the transfer residual toner adhering to the surface of the photosensitive member 52, thereby preventing a ghost or the like caused by the transfer residual toner remaining on the surface of the photosensitive member 52.

  Here, the developing device unit 58 is disposed on the lower right side of FIG. 2 of each photoconductor unit 50 and corresponds to each photoconductor 52 (52Y, 52M, 52K, 52C). 60Y, 60M, 60K, 60C) are arranged in the vertical direction.

  As shown in FIG. 2, the developing device unit 58 includes four developing devices 60, and each developing device 60 includes a box-shaped housing 110 and a lid 120 that closes the housing 110. In this method, a magnet roll 80 (developer carrier) for supplying toner to the photosensitive member 52 and a developer (toner and carrier) in the developing device 60 are agitated to charge the toner negatively and the carrier positively. A spiral auger 114 and a spiral auger 112 for supplying developer to the magnet roll 80 are rotatably supported.

  Each developing device 60 can move between a position where the magnet roll 80 abuts on the photoconductor 52 and a position where the magnet roll 80 is retracted from the photoconductor 52. When the toner is discharged, the magnet roll 80 contacts the photoconductor 52. It comes to touch. As a result, the toner adheres to the photosensitive member 52 corresponding to the electrostatic latent image formed on the photosensitive member 52. However, when the toner is not discharged, the developing unit 58 is in contact with the photosensitive member 52. Evacuates from.

  As shown in FIG. 3, each developing device 60 is provided with a metal layer thickness regulating member 124 in the vicinity of the magnet roll 80 along the axial direction of the magnet roll 80. The layer thickness of the developer supplied to is regulated. The layer thickness regulating member 124 has a substantially L-shaped cross section made of sheet metal or the like, and a filling member 126 made of synthetic resin or the like is accommodated in the layer thickness regulating member 124 and fixed to the layer thickness regulating member 124.

  The clogging member 126 can guide the developer to the gap between the layer thickness regulating member 124 and the magnet roll 80. Then, a magnetic brush having a predetermined height is formed by passing through the layer thickness regulating member 124 and rubs the photoreceptor 52 (see FIG. 2) as the magnet roll 80 rotates. A developing bias voltage in which a DC component is superimposed on an AC component is applied to the magnet roll 80, so that negative toner is attached to only the electrostatic latent image (image portion) of the photoreceptor 52 by electrostatic force. A toner image is formed.

  As shown in FIG. 2, an intermediate transfer unit 66 is disposed on the left side of the photoreceptor unit 50, and three drum-shaped intermediate transfer bodies 68, 70, and 72 are provided. The two first intermediate transfer members 68 and 70 are arranged vertically in the vertical direction, and the upper first intermediate transfer member 68 is arranged on the two photoconductors 52Y and 52M arranged at the upper portion of the photoconductor 52. The lower first intermediate transfer member 70 rotates in contact with the two photoconductors 52K and 52C disposed in the lower portion. A positive voltage (for example, +500 V) is applied to the first intermediate transfer bodies 68 and 70 in order to transfer negative toner, and the toner images on the photoreceptors 52Y and 52M are transferred to the first intermediate transfer bodies. 68, and the toner images on the photosensitive members 52K and 52C are transferred to the first intermediate transfer member 70, respectively. Further, the second intermediate transfer member 72 rotates in contact with both the first intermediate transfer members 68 and 70, and in order to transfer the negative toner on the first intermediate transfer members 68 and 70, the positive polarity. Voltage (for example, +1000 V) is applied, and the two color toner images on the first intermediate transfer bodies 68 and 70 are superimposed on the second intermediate transfer body 72 to form a full-color toner image. A full-color toner image is transferred onto a sheet by the transfer roll 74 (see FIG. 1).

  Further, a cleaning device 75 as a transfer residual toner collecting means comprising a cleaning roll 76 and a cleaning brush 78 is disposed in the vicinity of these intermediate transfer bodies 68, 70, 72, respectively. Transfer residual toner remaining on the surfaces of the transfer bodies 68, 70, 72 is collected.

  In the image forming apparatus 10, the toner images of the respective colors are transferred from the photosensitive member 52 to the first intermediate transfer members 68 and 70 and from the first intermediate transfer members 68 and 70 to the second intermediate transfer member 72. The transfer residual toner generated on the intermediate transfer bodies 68, 70, and 72 together with the negative polarity toner, such as charge injection due to the positive polarity voltage applied at the time of transfer, or micro discharge generated at the time of sheet peeling, etc. Due to the influence, a positive transfer residual toner whose polarity is reversed is generated. Therefore, the cleaning device 75 collects the negative transfer residual toner and the positive transfer residual toner by the two rolls of the cleaning roll 76 and the cleaning brush 78, respectively.

  Here, in the image forming apparatus 10 of the present embodiment, the driving force of the same motor (not shown) is used for the spiral auger 112 and the spiral auger 114 of the developing device 60 (60Y, 60M, 60K, 60C) in order to reduce the size of the apparatus. Each color developer (toner and carrier) is agitated in the same manner. Therefore, for example, when monotone continues in the image formed by the image forming apparatus 10, the developer 60K consumes the black developer, but the developers 60Y, 60M, and 60C develop yellow, magenta, and cyan developers. Is not consumed. For this reason, in the developing devices 60Y, 60M, and 60C, if the developer becomes excessive, the toner density of each color that adheres to the electrostatic latent image on the photosensitive member 52 is adjusted. The amount of the developer discharged inside each photoconductor 52 is adjusted. The discharged excessive toner may be ejected more than the amount of solid image toner in image formation, and from the first intermediate transfer bodies 68 and 70 to the second intermediate transfer in the same manner as the toner image in image formation. The toner is transferred to the body 72 and is collected as a transfer residual toner by the cleaning device 75 mainly in contact with the second intermediate transfer body 72 in the same manner as in the image formation.

  As shown in FIGS. 4 and 5, the cleaning device 75 has a cleaning roll 76 and a cleaning brush 78 rotatably fixed in the cover housing 130, and is driven by a cleaning device driving motor 166 (see FIG. 6). Rotate around the axis by force. The cleaning roll 76 is a metal rigid body, and applies a positive voltage (for example, +1200 V) to adhere negative transfer residual toner on the intermediate transfer bodies 68, 70, 72 based on electrostatic force. A metal blade 132 is in contact with the cleaning roll 76, and the attached negative transfer residual toner is carried into the temporary storage chamber 134 as the cleaning roll 76 rotates, and is temporarily moved into the temporary storage chamber 134 by the edge of the blade 132. It is scraped off. The temporary storage chamber 134 is provided with an auger 136 as a conveying means wound in a spiral shape around a predetermined axis, and is used for driving a cleaning device in conjunction with a cleaning roll 76 and a cleaning brush 78 by a gear (not shown). It is rotated around the axis by the driving force of the motor 166 (see FIG. 6), and the untransferred toner can be discharged from the discharge port 138 (see FIG. 5) provided on one end side by a certain amount. The discharge port 138 is inserted into a collection container (not shown), and the discharged transfer residual toner is held in the collection container. Here, since the cleaning roll 76 is made of metal, it can be rubbed with the metal blade 132 and has better cleaning performance than the conventional synthetic resin. Both the cleaning roll 76 and the blade 132 are made of metal. Therefore, wear is less than when both are made of synthetic resin.

  The cleaning roll 76 collects negative transfer residual toner, but the blade 132 is slightly separated from the cleaning roll 76 by the transfer residual toner adhering to the cleaning roll 76. In addition, wear of the edge of the blade 132 can be suppressed. However, if image formation with low image density continues, the amount of toner discharged from each developing device 60 also decreases, so the amount of residual transfer toner also decreases, and the residual transfer toner becomes insufficient between the cleaning roll 76 and the blade 132. As a result, the contact area increases and wear occurs. Therefore, in the image forming apparatus 10 of the present embodiment, when image formation with a low image density continues, a fixed amount of toner is discharged from the developing device 60 during non-image formation, and a predetermined voltage ( For example, by applying +1200 V), the transfer residual toner is adhered by electrostatic force, and cleaning assist is performed so as to adjust to an appropriate separated state. It should be noted that the image density is as low as 2 to 5% for a character image, the image density is as high as 90 to 100% for a solid image in the entire image area, and the average image density is 50% for a general image. It is known that each color is adjusted so that

  On the other hand, the brush of the cleaning brush 78 of the cleaning device 75 has brush hairs implanted on the surface thereof, and a negative voltage (for example, −500 V) is applied at the time of image formation. A positive transfer residual toner is adhered and temporarily held, and a positive voltage (for example, +1200 V) is applied every time a certain number of images (for example, 100 sheets) are formed. The toner is discharged onto the intermediate transfer members 68, 70, 72, the intermediate transfer members 68, 70, 72 are rotated and conveyed to the cleaning roll 76, and a negative voltage (for example, −500 V) is applied to the cleaning roll 76. Thus, the positive transfer residual toner is adhered and collected.

  Next, the configuration of the controller that performs toner density adjustment and cleaning assist shown in FIG. 6 will be described.

  The image formation control unit 150 is connected to the toner amount calculation unit 152. The image forming control unit 150 controls image forming processing on paper. When image data is input, the image forming control unit 150 uniformly rotates the charging members 56 while rotating the photoreceptors 52Y, 52M, 52K, and 52C. It is charged and laser light L (Y), L (M), L (K), and L (C) based on image data is scanned and exposed from the exposure unit 62 to electrostatically charge the photosensitive members 52Y, 52M, 52K, and 52C. A latent image is formed, and development is performed by attaching toners of Y, M, K, and C colors with developing devices 60Y, 60M, 60K, and 60C to form toner images of the respective colors. The image formation control unit 150 transfers the formed toner images on the photoconductors 52Y and 52M so as to be superimposed on the first intermediate transfer body 68 that rotates in contact with each other, and the toner images on the photoconductors 52K and 52C. Is transferred so as to be superimposed on the first intermediate transfer body 70 rotating in contact, and the toner image on the first intermediate transfer bodies 68 and 70 is transferred so as to be superimposed on the second intermediate transfer body 72 rotating in contact. The toner image is formed. Further, the formed full-color toner image is sent out from the paper tray 22 and transferred to the paper reaching the transfer roll 74 so as to be conveyed through the paper feed path 30 and synchronized, thereby forming an image on the paper.

  In addition, the image formation control unit 150 sends the image data subjected to the image formation processing to the toner amount calculation unit 152.

  The toner amount calculation unit 152 is connected to the image formation control unit 150, the auger rotation time calculation unit 162, the cumulative toner amount storage unit 154, and the cleaning assist determination unit 158. The toner amount calculation unit 152 counts the number of yellow (Y), magenta (M), black (K), and cyan (C) pixels of an image formed based on the image data sent from the image formation control unit 150. Thus, the toner amount of each color discharged from each developing device 60 in the image forming process is calculated. The toner amount calculation unit 152 sends the calculated toner amount of each color to the auger rotation time calculation unit 162, the cumulative toner amount storage unit 154, and the cleaning assist determination unit 158.

  The cumulative toner amount storage unit 154 is connected to the toner amount calculation unit 152, the toner density adjustment determination unit 156, and the toner discharge control unit 160. The accumulated toner amount storage unit 154 accumulates and stores the toner amount of each color discharged from each developing device 60 in the image forming process sent from the toner amount calculation unit 152 for each color. When an initialization instruction is received from a toner discharge control unit 160 described later, the accumulated toner amount for each stored color is initialized, and a new accumulation is started.

  The toner density adjustment determination unit 156 is connected to the cumulative toner amount storage unit 154 and the toner discharge control unit 160. The toner density adjustment determination unit 156 reads the accumulated toner amount of each color stored in the accumulated toner amount storage unit 154, and calculates the difference between the accumulated toner amount of the color having the largest accumulated amount and the accumulated toner amounts of the other three colors. When each added value becomes a predetermined value, a toner discharge instruction is sent to the toner discharge control unit 160. This is because, for example, when the image formed by the image data is monotone, only the black (K) toner is consumed, and the yellow, magenta, and cyan toners are not consumed. Therefore, the developing devices 60Y, 60M, and 60C This is because the toner density is adjusted by discharging excessive toner.

  The cleaning assist determination unit 158 is connected to the toner amount calculation unit 152 and the toner discharge control unit 160. The cleaning assist determination unit 158 stores a counter n, and the total toner amount sent from the toner amount calculation unit 152 is a toner amount having a constant density (for example, an image density of 5%) as a whole image. It is determined whether or not it is less than or equal to a certain density. When the toner amount of each color is larger than a certain density, the counter n is initialized. That is, the counter stores how many times the image forming process of a certain density or less has been continuously performed. When the counter n reaches a predetermined value (for example, 50), the cleaning assist determination unit 158 sends a toner discharge instruction to the toner discharge control unit 160. This is because, if image forming processing with a low toner density continues, a shortage of transfer residual toner occurs between the cleaning roll 76 of the cleaning device 75 and the blade 132 and wear occurs. This is because the separation state is adjusted by discharging the toner and collecting the toner by the cleaning device 75.

  The toner discharge control unit 160 is connected to the cumulative toner amount storage unit 154, the toner density adjustment determination unit 156, the cleaning assist determination unit 158, and the auger rotation time calculation unit 162. When the toner discharge control unit 160 receives a toner discharge instruction from the toner density adjustment determination unit 156, the toner discharge control unit 160 reads the total toner amount of each color from the total toner amount storage unit 154, and determines the total toner amount of the color with the largest total amount and the other three. The amount of toner discharged from each developing device 60 is calculated according to the difference from the accumulated toner amount of color, and the amount of toner calculated from each developing device 60 is discharged. Also, when a toner discharge instruction is received from the cleaning assist determination unit 158, the amount of toner discharged from each developing device 60 is set to a constant value, and each developing device 60 discharges a constant amount of toner. Further, the toner discharge control unit 160 rotates each photosensitive member 52, the first intermediate transfer members 68 and 70, and the second intermediate transfer member 72 to perform transfer in the same manner as in the image formation, and discharges the discharged color toners. It is conveyed to the cleaning device 75.

  Further, the toner discharge control unit 160 sends the toner amount discharged from each developing device 60 to the auger rotation time calculation unit 162, and initializes the accumulated toner amount stored in the accumulated toner amount storage unit 154. Send instructions.

  Here, the toner discharge control unit 160 calculates the amount of toner discharged from each developing device 60, but the total discharged toner amount D, which is the total amount of toner discharged from each developing device 60, is a temporary amount of the cleaning device 75. When the capacity of the storage chamber 134 is V, the amount of toner to be ejected from each developing device 60 is calculated so as to be 1/3 or less of the capacity V. As shown in FIG. 7, when the total discharged toner amount D exceeds 1/3 of the capacity V, the torque for rotating the auger 136 by the cleaning device driving motor 166 greatly increases and exceeds a predetermined allowable torque. This is because an excessive force is applied to a gear (not shown) that rotates the auger 136 and the gear is damaged. Therefore, the toner density adjustment determination unit 156 determines a value obtained by adding the difference between the cumulative toner amount of the color having the largest cumulative amount and the cumulative toner amounts of the other three colors, as the total discharged toner The amount D is an appropriate value that is 1/3 or less of the capacity V of the temporary storage chamber 134.

The auger rotation time calculation unit 162 is connected to the toner amount calculation unit 152, the toner discharge control unit 160, and the cleaning device control unit 164. The auger rotation time calculation unit 162 receives the toner amount discharged from each developing device 60 from the toner amount calculation unit 152 and the toner discharge control unit 160, and rotates the total discharge toner amount D and the auger 136, which are the sum of the toner amounts. The driving time T for rotating the auger 136 is calculated from the relationship of the following equation (3) from the transport amount R per unit time transported from the temporary storage chamber 134 to the collection container.
D ≦ R × T (3)
D: Total discharged toner amount R: Conveyed amount per unit time T: Driving time for rotating the auger Driving time T for rotating the auger 136 is determined so as to satisfy the expression (3), and discharged from each developing device 60. Even if all the remaining toner becomes transfer residual toner and is collected by the cleaning device 75 and stored in the temporary storage chamber 134, all of the transfer residual toner stored in the temporary storage chamber 134 can be conveyed to the recovery container. The auger rotation time calculation unit 162 sends the calculated drive time T to the cleaning device control unit 164.

  The cleaning device control unit 164 is connected to the auger rotation time calculation unit 162 and the cleaning device drive motor 166. The cleaning device control unit 164 applies a positive voltage (for example, +1200 V) to the cleaning roll 76 of the cleaning device 75 and a negative voltage (for example, −500 V) to the cleaning brush 78, and performs intermediate transfer 68, 70, 72. The negative transfer residual toner is attached to the cleaning roll 76 and collected in the temporary storage chamber 134, and the positive transfer residual toner is attached to the cleaning brush 78.

  Further, the cleaning device control unit 164 controls the cleaning device driving motor 166 to rotate the auger 136 for the driving time T, thereby conveying the transfer residual toner in the temporary storage chamber 134 to the collection container.

  Next, the operation of the present embodiment will be described using the flow shown in FIG.

  In step 200, image data is input to the image formation control unit 150, and the laser light L (Y (Y) based on the image data from the exposure unit 62 on the photoreceptors 52 Y, 52 M, 52 K, and 52 C uniformly charged by the charging roll 56. ), L (M), L (K), and L (C) are scanned to form an electrostatic latent image, and each color toner is discharged from the developing devices 60Y, 60M, 60K, and 60C, and development is performed. A toner image of each color is formed, and the toner images on the formed photoreceptors 52Y and 52M are superimposed on the first intermediate transfer member 68, and the toner images on the photoreceptors 52K and 52C are superimposed on the first intermediate transfer 70. In addition, the toner image on the first intermediate transfer bodies 68 and 70 is transferred so as to overlap the second intermediate transfer body 72 to form a full-color toner image. Further, the formed full-color toner image is sent out from the paper tray 22, transferred to the paper feed path 30, and transferred to the paper that has reached the transfer roll 74 so as to be synchronized, and an image is formed on the paper. Migrate to

  In step 202, the toner amount of each color ejected in the image forming process is calculated based on the image data, and the toner amount for each color is accumulated, and the process proceeds to step 204.

  In step 204, the driving time T of the auger 136 of the cleaning device 75 is calculated from the total amount (total discharged toner amount D) of each color discharged in the image forming process during image formation by the above-described equation (3). Move to 206.

  In Step 206, in order to collect the transfer residual toner generated at the time of image formation, a positive voltage (for example, +1200 V) is applied to the cleaning roll 76 to remove the negative transfer residual toner on the intermediate transfer 68, 70, 72. It is attached and collected in the temporary storage chamber 134. Further, a negative voltage (for example, −500 V) is applied to the cleaning brush 78 to cause the positive transfer residual toner on the intermediate transfer 68, 70, 72 to adhere to the cleaning brush 78.

  Further, the cleaning device driving motor 166 is controlled to rotate the auger 136 for the driving time T, so that the negative transfer residual toner recovered in the temporary storage chamber 134 is conveyed to the recovery container and the process proceeds to Step 208.

  In step 208, if the sum of the difference between the cumulative toner amount of the color with the largest cumulative toner amount accumulated in step 202 and the cumulative toner amount of the other three colors is equal to or greater than a predetermined value, Since only the color toner is consumed and the toner density needs to be adjusted, an affirmative determination is made and the routine proceeds to step 212.

  On the other hand, if the value obtained by adding the difference between the cumulative toner amount of the color with the largest cumulative toner amount and the cumulative toner amount of the other three colors is less than the predetermined value, the toner density adjustment is not necessary, so step 208 is If a negative determination is made, the process proceeds to step 210.

  In step 210, when the image density formed by the image forming process is 5% or less, the value of the counter n stored in the cleaning assist determination unit 158 is incremented by 1. As a result of the addition, the value of the counter n is 50. In this case, an affirmative determination is made in step 210 and the process proceeds to step 212. If the counter n is incremented by 1 but the value is less than 50, a negative determination is made in step 210 and the process returns to the image forming process in step 200. Further, when the density of the image formed by the image forming process is higher than 5%, a negative determination is made in step 210, the value of the counter n is initialized to 0, and the process returns to the image forming process of step 200.

  In step 212, the toner amount to be discharged for each color is calculated from the cumulative toner amount for each color to adjust the toner density, and the toner amounts calculated from the developing devices 60Y, 60M, 60K, and 60C are discharged. Further, the photosensitive member 52, the first intermediate transfer members 68 and 70, and the second intermediate transfer member 72 are rotated to perform transfer in the same manner as in the image formation, and the discharged toner of each color is conveyed to the cleaning device 75. Control goes to step 214.

  In step 214, the driving time T of the auger 136 of the cleaning device 75 is calculated from the total amount of toner discharged from the developing devices 60Y, 60M, 60K, and 60C in step 212 (total discharged toner amount D) by the above-described equation (3). Calculate and move to step 216.

  In step 216, a positive voltage (for example, +1200 V) is applied to the cleaning roll 76 and discharged from the developing devices 60 Y, 60 M, 60 K, and 60 C for toner density adjustment or cleaning assistance, and intermediate transfer 68, 70, 72. The transfer residual toner remaining on the top is attached and collected in the temporary storage chamber 134. In addition, the cleaning device driving motor 166 is controlled to rotate the auger 136 for the driving time T calculated in step 214 to convey the transfer residual toner stored in the temporary storage chamber 134 to the recovery container.

  As described above, according to the image forming apparatus 10 of the present embodiment, each developing device is determined by determining the driving time T of the auger 136 according to the amount of toner discharged from each developing device 60 and the conveying ability of the auger 136. It is possible to prevent the transfer residual toner discharged from 60 and collected by the cleaning device 75 from remaining in the temporary storage chamber 134. Even when a large amount of toner is discharged from each developing device 60 at the time of adjusting the toner density than during normal image formation, the discharged toner is collected by the cleaning device 75 and transferred to the collection container. Can do.

  Further, since the total amount of toner discharged from each developing device 60 is set to a capacity of 1/3 or less of V in the temporary storage chamber 134 of the cleaning device 75, excessive torque is not required to rotate the auger 136. The device can be prevented from being damaged.

  In this embodiment, the driving time T for rotating the auger is set from the transport amount R per unit time and the total discharged toner amount D. However, the driving time T for rotating the auger, the transport amount R per unit time, and The total discharged toner amount D may be set so as to satisfy the expression (3). In this case, the transport amount R per unit time can be changed by changing the rotation speed of the cleaning device driving motor 166 that rotates the auger 136.

  In the present embodiment, the toner discharge control unit 160 determines the total amount of discharged toner to be 1/3 or less of the capacity V of the temporary storage chamber 134, but the total amount of toner discharged for density adjustment is particularly Without limitation, when the total amount of toner exceeds 1/3 of the capacity V, the toner discharge control unit 160 divides the volume so that it becomes 1/3 of the capacity V, and discharges the toner in multiple times. Also good.

  Further, in this embodiment, the cleaning device 75 is provided on the intermediate transfer bodies 68, 70, and 72. However, the transfer residual toner may be collected by being provided on each photoconductor 52.

1 is a side view of an image forming apparatus according to an embodiment of the present invention. 1 is an enlarged view of a main part of an image forming apparatus according to an embodiment of the present invention. FIG. 2 is an enlarged view of a developing device according to an embodiment of the present invention. It is an enlarged view of the cleaning apparatus which concerns on embodiment of this invention. It is a perspective view of the cleaning device concerning the embodiment of the present invention. FIG. 4 is a block diagram relating to toner discharge control according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a relationship between toner discharge amount and torque according to an exemplary embodiment of the present invention. It is a flow which shows the flow of control which concerns on embodiment of this invention.

Explanation of symbols

Image forming apparatus 10
Photoconductor 52, 52Y, 52M, 52K, 52C (image carrier)
Developer 60, 60Y, 60M, 60K, 60C (developing means)
Intermediate transfer member 68, 70, 72
Cleaning device 75 (transfer residual toner collecting means)
Cleaning roll 76 (transfer residual toner collecting mechanism)
Blade 132
Temporary storage chamber 134
Auger 136 (conveying means)
Toner discharge controller 160 (toner condition controller)
Auger rotation time calculation unit 162 (setting means)

Claims (3)

An electrostatic latent image showing an image of each color of yellow, magenta, black, and cyan is formed on each of the plurality of image carriers, and the electrostatic latent images formed on the plurality of image carriers are An image forming apparatus that develops a corresponding color toner from a plurality of developing units provided on each of a plurality of image carriers, and transfers the developed toner image of each color to a recording medium via an intermediate transfer member Because
Calculating means for calculating the amount of toner of each color attached from the plurality of developing means based on the image data;
Storage means for accumulating and storing the toner amount of each color calculated by the calculation means for each color;
The accumulated toner amount of each color stored in the storage means is read, and each difference between the accumulated toner amount of the color with the largest accumulated amount and the accumulated toner amounts of the other three colors other than the color with the largest accumulated amount is added. Toner discharge control means for performing control to cause toner to be discharged from each developing means in accordance with the difference when the value is equal to or greater than a predetermined value;
An image forming apparatus comprising: A toner collecting mechanism that is disposed opposite to at least one of the image carrier or the intermediate transfer member and collects toner on at least one of the image carrier or the intermediate transfer member, and temporarily stores the collected toner. A temporary storage chamber, and a toner collecting means comprising:
A transporting means for transporting the toner stored in the temporary storage chamber in a predetermined direction in conjunction with the toner recovery mechanism;
A collection container that is provided in a conveyance direction by the conveyance unit and that finally collects and holds the toner;
Further comprising
Each amount of toner discharging the developing means, the image forming apparatus according to claim 1 Symbol mounting, characterized in that said one-third or less of the capacity of the temporary storage chamber by said toner discharge control means. A cleaning roller that pre Quito toner collecting mechanism is based on the electrostatic force generated by the predetermined voltage is applied to deposit the door toner on the peripheral surface,
The contact with the peripheral surface of the cleaning roller, adhering to have the image forming apparatus according to claim 2, characterized in that it is a blade and, in configuration to guide to the temporary storage chamber by scraping the belt toner.

Images