JP4836443B2 - Cleaning device and image forming apparatus equipped with the same - Google Patents

Description

  The present invention relates to a cleaning device that removes toner remaining on the surface of an image carrier and cleans it after transferring a toner image onto a sheet. The present invention also relates to an image forming apparatus equipped with this cleaning device.

  In an electrophotographic image forming apparatus, as a method of transferring a toner image formed on the surface of a photosensitive drum as an image carrier to a sheet, the toner image is transferred by directly contacting the sheet with the photosensitive drum, Further, a method is used in which a toner image is temporarily transferred to an intermediate transfer member composed of another drum or belt and then secondarily transferred to a sheet. Among these, when performing color printing using a plurality of different colors, the latter transfer method using an intermediate transfer member is widely used. In this case, a plurality of color toners are sequentially transferred to the intermediate transfer member in order to form a color toner image on the surface of the intermediate transfer member, and the completed color toner image is finally transferred onto the sheet.

  In such transfer methods, after a toner image is transferred to a sheet or an intermediate transfer member, a small amount of toner may not be transferred and may remain on the surface of the photosensitive drum. Since the residual toner on the surface of the photosensitive drum becomes an obstacle to the next new image formation, it needs to be cleaned. As a cleaning method used for such a purpose, there is a method in which a rotating member such as a roller or a rotating brush is pressed against the surface of the photosensitive drum to move and collect the residual toner on the rotating member, or a blade is used on the photosensitive drum surface. A method of scraping residual toner by contact, or a cleaning method combining these methods is widely known.

  On the other hand, in an image forming apparatus using toner, in recent years, the diameter of the toner has been reduced with the aim of forming a clear and high-quality image. Conventionally, as a method for producing toner, a pulverization method has been used in which heated plastic material is blown off with a strong air current and hit against a wall to be crushed to produce toner particles. However, if the diameter of the toner is reduced by the pulverization method, the yield is poor, and there is a concern that the production of the toner may increase in cost.

  Therefore, recently, a polymerization method is expanding as a method for producing a small-diameter toner in place of the pulverization method. The polymerization method is a method in which toner particles are produced by combining substances that form the toner by a chemical reaction. Since the polymerization method consumes less energy than the conventional pulverization method, it is attracting attention as an environmentally friendly toner production method. By this polymerization method, a toner having a small diameter and a uniform shape and size can be generated, so that it is possible to form a clearer and higher quality image.

However, the toner produced by the polymerization method has a problem that it has a small diameter and is more spherical, and it is very difficult to clean. That is, since the toner manufactured by the polymerization method has a shape that the surface is difficult to be caught, it is difficult to clean the toner by attaching it to a rotating member or a blade. Therefore, a cleaning device has been proposed that can obtain good cleaning performance by using an irregular toner in addition to the spherical toner for cleaning the spherical toner manufactured by a polymerization method or the like. Can be seen.
JP-A-8-254873 (page 6-10, FIG. 2-5)

  In the cleaning method for an image forming apparatus described in Patent Document 1, a development region with an irregular shaped toner is formed in a non-image portion at the front end side in the surface movement direction of the photosensitive drum prior to development of an image portion with spherical toner. Accordingly, the irregular toner is interposed between the blade and the spherical toner at the time of cleaning so that the spherical toner can be easily cleaned. However, in this method, since the irregular toner is developed in the non-image portion, useless toner that is not transferred onto the paper is wasted. Therefore, the running cost is increased, and there is a risk that the environment may be adversely affected in terms of resource saving.

  The present invention has been made in view of the above points, and maintains suitable cleaning performance for toner remaining on the surface of an image carrier without impairing a clear and high-quality image obtained by using a spherical toner. It is an object of the present invention to provide a cleaning device that can do this. It is another object of the present invention to provide a high-performance image forming apparatus equipped with such a cleaning apparatus and considering resources and the environment at a low running cost.

  In order to solve the above-mentioned problems, the present invention uses a plurality of toners of different colors, irregular and spherical, and remains on the surface of an image carrier that repeats development, transfer, and cleaning processes for each color. In a single cleaning device that sequentially cleans each color toner for each process, a blade that contacts the image carrier and scrapes the toner adhering to the surface thereof is provided upstream of the blade in the image carrier rotation direction. A rotating member that contacts the image carrier, a driving unit that rotates the rotating member, and a control unit that controls the driving unit. The first cleaning is performed, and the control means selects the rotation method of the rotating member during the cleaning operation.

  Further, the controller moves the surface of the rotating member in a direction different from the surface of the image carrier until the image forming operation for all the colors on the image carrier is completed. When the image forming operation for all colors is completed, the surface in contact with the image carrier is rotated in the same direction as the surface of the image carrier.

  Further, the control means rotates the rotating member in such a direction that the surface at the contact point with the image carrier moves in a direction different from the surface of the image carrier when cleaning the irregular toner, At the time of cleaning, the surface at the contact point with the image carrier is rotated in a direction to move in the same direction as the surface of the image carrier.

  The rotating member rotates according to the rotation of the image carrier when rotating in a direction in which the surface at the contact point with the image carrier moves in the same direction as the surface of the image carrier.

  In addition, a power supply unit that applies a bias voltage to the rotating member is provided, and the control unit controls the power supply unit to switch the bias voltage applied to the rotating member during a cleaning operation.

  The control means applies a voltage having a polarity opposite to that of the toner to the rotating member until the image forming operation for all colors on the image carrier is completed, and rotates from the end of the image forming operation for all colors. The voltage having the same polarity as that of the toner was applied until the member stopped.

  Further, the control means applies a voltage having a polarity opposite to that of the toner when the irregular toner is cleaned to the rotating member, and applies a voltage having the same polarity as that of the toner when cleaning the spherical toner.

  The irregular toner is a black toner, and the spherical toner is a toner other than black.

  Further, in the image forming operation for all colors, the spherical toner weight Ws and the irregular toner weight Wu remaining between the blade and the rotating member in the vicinity of the surface of the image carrier are (Ws / Wu) The blade and the rotating member are arranged to have a relationship of <1.5.

  In the present invention, the cleaning device is mounted on the image forming apparatus.

  According to the configuration of the present invention, in the cleaning device for the toner remaining on the surface of the image carrier that repeats the image forming process for each of a plurality of colors, the blade that contacts the image carrier and scrapes the toner adhering to the surface; The blade is provided on the upstream side of the image carrier rotating direction of the blade, and includes a rotating member that contacts the image carrier, a driving unit that rotates the rotating member, and a control unit that controls the driving unit. In addition, the irregular toner is first cleaned among the plurality of spherical toners, and the control unit selects the rotation method of the rotating member during the cleaning operation. The period of staying around the blade can be arbitrarily selected. This makes it possible to mix and clean a suitable amount of irregular toner when cleaning the spherical toner. Therefore, it is possible to obtain a suitable cleaning performance for the toner remaining on the surface of the image bearing member without impairing a clear and high-quality image obtained by using a spherical toner having a small diameter and a uniform shape and size. it can.

  Further, the control means rotates the rotating member in such a direction that the surface at the contact point with the image carrier moves in a direction different from the surface of the image carrier until the image forming operation for all colors on the image carrier is completed. At the end of the image forming operation for all colors, the surface at the contact point with the image carrier is rotated so that the surface moves in the same direction as the surface of the image carrier. The toner remaining in the toner can stay around the rotating member and the blade until the image forming operation for all colors is completed. As a result, it is possible to simultaneously clean all of the irregular and spherical toners remaining on the surface of the image carrier for a plurality of irregular and spherical toners of different colors. Therefore, the cleaning performance of the spherical toner using the irregular toner is improved.

  Further, the control means rotates the rotating member in such a direction that the surface in contact with the image carrier moves in a direction different from the surface of the image carrier when cleaning the irregular toner, and when cleaning the spherical toner, Since the surface at the contact point with the image carrier is rotated so that the surface moves in the same direction as the surface of the image carrier, the irregular toner is retained around the rotating member and blade until the spherical toner cleaning starts. When cleaning a plurality of different color spherical toners, the spherical toners can be sequentially discharged together with the irregular toner for each color. This makes it possible to reduce the spherical toner of the previously developed color existing around the rotating member and the blade as much as possible when cleaning the spherical toner of the developed color later. Therefore, the cleaning performance of the spherical toner is further improved.

  The rotating member is rotated according to the rotation of the image carrier when the surface at the contact point with the image carrier rotates in the same direction as the surface of the image carrier. Rotating time can be shortened. As a result, the energy consumed by the driving means can be reduced, so that a cleaning device that saves energy can be obtained. In addition, since it is not necessary to provide the drive means with a function of switching the rotation direction of the rotating member, the cost of the cleaning device can be reduced.

  In addition, since the power supply unit that applies a bias voltage to the rotating member is provided and the control unit controls the power supply unit to switch the bias voltage applied to the rotating member during the cleaning operation, the rotating member and the toner are In the case of reverse polarity, the properties of attracting each other and repelling each other in the same polarity can be used for toner cleaning. As a result, it is possible to increase the action of retaining the irregular shaped toner around the rotating member and the blade until the spherical toner starts cleaning, and it is possible to suppress the irregular shaped toner from being scattered to other places. It becomes. Therefore, when cleaning the spherical toner, it becomes possible to mix more irregular toner and clean it. As a result, the cleaning performance for the toner remaining on the surface of the image carrier can be further improved.

  The control means applies a voltage having a polarity opposite to that of the toner to the rotating member until the image forming operation for all colors on the image carrier is completed, and the rotating member stops from the end of the image forming operation for all colors In the meantime, the voltage having the same polarity as that of the toner is applied. It can make it easy to stay around. As a result, the effect of simultaneously cleaning all the amorphous and spherical toners remaining on the surface of the image carrier is enhanced, and the cleaning performance of the spherical toner using the irregular toner is further improved.

  Further, the control means applies a voltage having a polarity opposite to that of the toner when cleaning the irregular toner to the rotating member, and applies a voltage having the same polarity as that of the toner when cleaning the spherical toner. It is possible to enhance the action of retaining the irregular shaped toner around the rotating member and the blade until the cleaning is started and the action of sequentially discharging the spherical toner together with the irregular shaped toner for each color. As a result, the effect of removing the spherical toner of the previously developed color from the periphery of the rotating member and the blade before starting the cleaning of the spherical toner of the subsequent color is enhanced, and the cleaning performance of the spherical toner is further improved.

  In addition, since the irregular toner is a black toner and the spherical toner is a toner other than black, a spherical toner having a small diameter and a uniform shape and size can be used as the color toner. As a result, a clearer and higher quality color image can be obtained, and the cleaning performance can be improved by the irregular black toner.

  Further, in the image forming operation for all colors, the spherical toner weight Ws and the irregular toner weight Wu remaining between the blade and the rotating member in the vicinity of the surface of the image carrier are (Ws / Wu) <1. Since the blade and the rotating member are arranged so as to have a relationship of 5, even when a large amount of spherical toner is used to form a clear and high-quality image, the toner remaining on the surface of the image carrier It is possible to maintain a suitable amount of irregular shaped toner for cleaning. Therefore, it is possible to obtain a clear and high-quality image, suppress wasteful waste of irregularly shaped toner, and obtain a cleaning device considering resources and the environment at a low running cost.

  In the present invention, since the cleaning device is mounted on the image forming apparatus, the toner remaining on the surface of the image carrier can be obtained without impairing the clear and high-quality image obtained by using the spherical toner. It is possible to obtain a high-performance image forming apparatus that can maintain a suitable cleaning performance and is low in running cost and is resource and environmentally friendly.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

  First, an outline of the structure of an image forming apparatus equipped with a cleaning device according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a left side view of a schematic vertical section showing a schematic structure of a color printer which is an example of an image forming apparatus. This color printer is a type using an intermediate transfer belt. In FIG. 1, the right side is the front side of the printer, and the left side is the back side.

  As shown in FIG. 1, a paper cassette 3 is disposed below the inside of the main body 2 of the printer 1. Inside the paper cassette 3, paper P is stacked and stored. Then, the paper P is sent out toward the upper right of the paper cassette 3 in FIG. The paper cassette 3 can be pulled out horizontally from the front side of the main body 2, that is, from the right side in FIG.

  A paper feed paper transport path 4, a paper feed transport roller 5, a registration roller 6, and an image forming unit 20 are disposed downstream of the paper cassette 3 in the paper transport direction. The image forming unit 20 includes a photosensitive drum 21 which is a rotating image carrier at the center thereof. The photosensitive drum 21 rotates counterclockwise in FIG. Around the photosensitive drum 21, a charging device 22, a developing device 23, and a drum cleaning device 30 are sequentially arranged along the rotation direction.

  The developing device 23 is mainly composed of a rotary rack 23a which is a rotating body that rotates clockwise in FIG. 1, and a total of four developing devices are arranged at equal intervals in the circumferential direction on the rotary rack 23a. The four developing devices are a black developing device 23B, a cyan developing device 23C, a magenta developing device 23M, and a yellow developing device 23Y. The rotary rack 23a is rotated by driving means (not shown), and the four developing devices are sequentially moved to positions facing the photosensitive drum 21 to form toner images of respective colors on the surface of the photosensitive drum 21. .

  An intermediate transfer belt 24 using an intermediate transfer member in the form of an endless belt is disposed immediately below the photosensitive drum 21. The intermediate transfer belt 24 is in pressure contact with the photosensitive drum 21 from below. The intermediate transfer belt 24 is wound around and supported by a plurality of rollers, and rotates in the clockwise direction in FIG.

  A secondary transfer unit 40 is disposed at a position where the intermediate transfer belt 24 is suspended on the sheet conveyance path. The secondary transfer unit 40 includes a secondary transfer roller 41. The sheet P is inserted through a nip formed by the press-contact between the intermediate transfer belt 24 and the secondary transfer roller 41. Note that the secondary transfer roller 41 is movable in the vertical direction in FIG. 1, and is pressed against or separated from the intermediate transfer belt 24 as necessary. A belt cleaning device 25 is provided downstream of the secondary transfer unit 40 in the sheet conveyance direction. The belt cleaning device 25 is also pressed against or separated from the intermediate transfer belt 24 as necessary.

  An optical unit 7 is provided above the image forming unit 20, and a laser beam L is emitted from the optical unit 7 toward the photosensitive drum 21. A one-dot chain line in the figure indicates the laser beam L.

  A fixing unit 8, a discharge paper transport path 9, and a paper discharge unit 10 are disposed downstream of the image forming unit 20 and the secondary transfer unit 40 in the paper transport direction. The paper discharge unit 10 is provided on the upper surface of the main body 2 at a position where the printed paper P can be taken out from the outside.

  A paper conveyance path 11 for double-sided printing is disposed below the fixing unit 8 and the secondary transfer unit 40 and between the paper cassette 3. The double-sided printing paper conveyance path 11 branches from the middle of the discharge paper conveyance path 9 and joins the paper feeding paper conveyance path 4 immediately upstream of the registration rollers 6.

  The printer 1 having the above configuration performs a printing operation as follows.

  The paper P before printing is stored in the paper cassette 3 in a stacked state, and is sent out separately from here. The fed paper P enters the paper feed paper transport path 4, is transported by the paper feed transport roller 5, and reaches the registration roller 6. The registration roller 6 feeds the paper P to the secondary transfer unit 40 by correcting the oblique feeding of the paper P and timing the color toner image formed on the surface of the intermediate transfer belt 24 by the image forming unit 20.

  Image data signals such as characters, graphics, and patterns from an external computer (not shown) are transmitted to the printer 1, and laser light L controlled by the optical unit 7 is irradiated based on the image data. As a result, an electrostatic latent image of the original image is formed on the surface of the photosensitive drum 21 in the image forming unit 20.

  Next, among the colors of black, cyan, magenta, and yellow, first, a black toner image, which is the first color, is formed on the surface of the photosensitive drum 21 so that the black developing unit 23B faces the photosensitive drum 21. In addition, the rotary rack 23a rotates. The black developing device 23B develops the electrostatic latent image on the surface of the photosensitive drum 21 to form a black toner image. Thereafter, the toner image is transferred to the surface of the intermediate transfer belt 24. The toner remaining on the surface of the photosensitive drum 21 after the transfer is removed by the drum cleaning device 30. Subsequently, the same process as that for the first color is repeated from the second color to the fourth color, and a color toner in which toner images of four colors of black, cyan, magenta, and yellow are superimposed on the surface of the intermediate transfer belt 24. An image is formed.

  As described above, the secondary transfer roller 41 and the belt cleaning device 25 of the secondary transfer unit 40 are separated from the intermediate transfer belt 24 while the toner images of the respective colors are sequentially primary transferred to the intermediate transfer belt 24. When the four color toner images are formed on the surface of the intermediate transfer belt 24, the secondary transfer roller 41 comes into pressure contact with the intermediate transfer belt 24. The color toner image is transferred to the paper P sent in synchronization by the registration roller 6 at a nip portion formed by the intermediate transfer belt 24 and the secondary transfer roller 41 being pressed against each other. At this time, a transfer bias for moving the toner to the paper P is applied to the secondary transfer roller 41.

  Thereafter, the paper P carrying the unfixed color toner image is sent to the fixing unit 8, and the toner image is fixed by the heat roller and the pressure roller. The paper P discharged from the fixing unit 8 is sent upward through the discharge paper transport path 9 and is discharged to the paper discharge unit 10 provided on the upper surface of the main body 2.

  When duplex printing is performed, the transport direction of the paper P discharged from the fixing unit 8 is switched immediately before being discharged to the paper discharge unit 10 through the discharge paper transport path 9. Then, the paper P is sent to the double-sided printing paper transport path 11, merged with the paper feed paper transport path 4 immediately upstream of the registration roller 6, and sent again to the secondary transfer unit 40.

  Next, the detailed configuration of the cleaning apparatus according to the first embodiment of the present invention will be described with reference to FIG. 2 in addition to FIG. FIG. 2 is a schematic vertical sectional partial enlarged view showing the periphery of the cleaning device and a schematic diagram of the control circuit.

  As shown in FIGS. 1 and 2, the image forming unit 20 includes a photosensitive drum 21 as an image carrier at the center thereof. The cleaning device 30 is disposed in the vicinity of the photosensitive drum 21.

  The photoconductor drum 21 is an inorganic photoconductor having an amorphous photoconductive material provided with amorphous silicon on the outside of a conductive roller base made of aluminum or the like by vacuum deposition or the like, and has a diameter of 30 mm. The photosensitive drum 21 is rotated by a driving device (not shown) so that the peripheral speed thereof is the same as the paper conveyance speed (150 mm / s).

  The cleaning device 30 for the photosensitive drum 21 is disposed further downstream of the primary transfer nip portion along the rotation direction of the photosensitive drum 21 (see FIG. 1). As shown in FIG. 2, the cleaning device 30 includes a cleaning blade 31, a cleaning roller 32 that is a rotating member, a screw 33, and a housing 34.

  The cleaning blade 31 is made of urethane rubber having a hardness of 77 ° (conforming to JIS standard A), has substantially the same axial length and thickness of 2.2 mm as the photosensitive drum 21, and is in contact with the photosensitive drum 21. . The cleaning blade 31 is provided with respect to the photosensitive drum 21 such that the angle with the tangent at the contact location is 26 ° and the linear pressure at the contact location is 30 N / m. The arrangement method of the cleaning blade 31 will be described in detail later. The cleaning blade 31 performs cleaning so as to scrape off deposits such as toner remaining on the surface of the photosensitive drum 21.

  The cleaning roller 32 is configured by providing ethylene propylene rubber (EPDM) having a hardness of 55 ° (conforming to JIS standard A) around a core metal having a diameter of 8 mm, and the diameter of the roller portion is 12 mm. The cleaning roller 32 is provided by being pressed against the photosensitive drum 21 with a force of 1,000 gf (one side 500 gf) by urging means (not shown) provided at both ends of the shaft portion. The cleaning roller 32 serves to collect toner around the surface of the photosensitive drum 21 and the cleaning blade 31 and to send the toner toward the screw 33.

  After the toner image is transferred to the intermediate transfer belt 24 (see FIG. 1), the toner remaining on the photosensitive drum 21 is scraped off by the cleaning blade 31 and adheres to the cleaning roller 32 or directly moves to the cleaning roller 32. Or The toner adhering to the cleaning roller 32 is conveyed to the outside of the housing 34 by the screw 33.

  The cleaning roller 32 is rotated by driving means 50 constituted by a motor or the like. The driving unit 50 can switch the rotation direction of the cleaning roller 32 or rotate the cleaning roller 32 according to the rotation of the photosensitive drum 21. In order to perform cleaning efficiently, it is necessary to rotate the cleaning roller 32 at a predetermined surface speed. When the cleaning roller 32 is rotated in such a direction that the surface at the contact point with the photosensitive drum 21 moves in a direction different from the surface of the photosensitive drum 21, the surface speed of the cleaning roller 32 is 1.2 of that of the photosensitive drum 21. Is double. When the cleaning roller 32 is rotated in such a direction that the surface at the contact point with the photosensitive drum 21 moves in the same direction as the surface of the photosensitive drum 21, the surface speed of the cleaning roller 32 is 0.8 of that of the photosensitive drum 21. Is double. The driving unit 50 is controlled by the control unit 60, and the control unit 60 selects a rotation method of the cleaning roller 32 during the cleaning operation.

  Here, the toner that is a developer used for image formation will be described. As the black toner accommodated in the black developing device 23B of the rotary rack 23a shown in FIG. 1, the irregular toner is used as cyan toner, magenta toner, and yellow toner accommodated in the color developing devices 23C, 23M, and 23Y. Used a spherical toner.

  The black amorphous toner was produced by the following method. First, 5 parts by weight of carbon black (weight based on 100% of the weight of the polyester resin) and nigrosine N21 (produced by Orient Chemical Co., Ltd.) as a charge control agent (CCA) are mixed with the polyester resin. It knead | mixed for 30 minutes at 100 degreeC with this roll kneader. This was coarsely pulverized and then finely pulverized by a collision air jet jet air pulverizer. And it classify | categorized with the air classifier and obtained the powder with a volume average particle diameter of 7.8 micrometers. An amorphous toner can be obtained by adding 1.5 parts by weight of hydrophobic silica powder to this powder and mixing with a powder mixer. The charge amount by the suction method was plus 12 μC / g. As a result of measuring the sphericity of the irregular toner by a flow type particle image analyzer manufactured by Sysmex Corporation, it was 0.91 to 0.93.

  A three-color spherical toner was produced by the following method. First, 80 parts by weight of styrene, 20 parts by weight of 2-ethylhexyl methacrylate, 5 parts by weight of a colorant, 3 parts by weight of low molecular weight polypropylene, 2 parts by weight of a charge control agent (quaternary ammonium salt), and 1 part by weight of divinylbenzene (crosslinking agent) 2 parts by weight of a polymerization initiator and 2 parts by weight of 2-azobis (2,4-dimethylvaleronitrile) were added to a mixed solution of parts. This was added to 400 parts by weight of purified water, and 5 parts by weight of tribasic calcium phosphate and 0.1 part by weight of sodium dodecylbenzenesulfonate were added as a suspension stabilizer. Then, this was stirred for 20 minutes at a rotation speed of 7000 rpm using an emulsifier / disperser manufactured by Tokushu Kika Kogyo Co., Ltd., and subjected to a polymerization reaction at 70 ° C. and 100 rpm for 10 hours in a nitrogen atmosphere to obtain a volume average particle size of 6 A spherical toner of 4 μm was obtained. The charge amount by the suction method for the three colors was plus 33 μC / g for cyan, 29 μC / g for magenta plus, and 32 μC / g for yellow. The sphericity of these spherical toners was measured by a flow type particle image analyzer manufactured by Sysmex Corporation and found to be 0.96 to 0.99.

  In the cleaning device 30 configured as described above, a method for arranging the cleaning blade 31 and the cleaning roller 32 will be described with reference to FIG. FIG. 3 is a graph showing the influence of the spherical toner amount on the minimum linear pressure that can be cleaned.

  First, the minimum linear pressure that can be cleaned by the cleaning blade 31 was determined only for the black toner that is an irregular toner. This was performed by developing an image having no gap around the entire circumference of the photosensitive drum 21, and then visually observing the remaining wiping of the paper surface by the cleaning blade 31. If even a small amount of toner could be confirmed on the paper surface, it was judged that the cleaning was insufficient. As a result, the minimum linear pressure that can be cleaned by the cleaning blade 31 was 20 N / m. At this time, as a method of arranging the cleaning roller 32, as described above, the cleaning roller 32 is pressed against the photosensitive drum 21 with a force of 1,000 gf.

  Then, as shown in FIG. 3, the minimum linear pressure that can be cleaned when the amount of spherical toner for color is gradually increased from the case of using only irregular shaped toner is determined. The horizontal axis of FIG. 3 shows the spherical toner weight Ws with respect to the irregular toner weight Wu. The toner weight is the same at 1.0, and the spherical toner increases toward the right. The vertical axis represents the minimum linear pressure that can be cleaned by the cleaning blade 31. The higher the pressure is, the higher the linear pressure is required, that is, the higher the pressure is, the stronger the pressing force is required to press the cleaning blade 31 against the photosensitive drum 21.

  According to FIG. 3, the spherical toner weight Ws and the irregular toner weight Wu remaining between the cleaning blade 31 and the cleaning roller 32 in the vicinity of the surface of the photosensitive drum 21 in the image forming operation for all colors are ( It can be seen that the minimum cleanable linear pressure gradually increases beyond the case where the relationship of Ws / Wu) <1.5 is exceeded. That is, when the spherical toner increases beyond the case of (Ws / Wu) <1.5, the cleaning performance is deteriorated.

  Here, generally, the spherical toner has a high transfer efficiency, and the amount of toner remaining on the surface of the photosensitive drum 21 is 5% or less (about 4% in this experiment) of the supplied toner amount (development toner amount). On the other hand, 10 to 20% (about 18% in this experiment) of the irregular shaped toner remains. As a result, when the black amorphous toner is the least and the three color color spherical toners remain the most, the relationship between the spherical toner weight Ws and the irregular toner weight Wu is approximately (Ws / Wu) = 1.5. It becomes.

  Therefore, the cleaning blade 31 and the cleaning roller 32 of the cleaning device 30 of the present invention are spherical and remain between the cleaning blade 31 and the cleaning roller 32 in the vicinity of the surface of the photosensitive drum 21 in the image forming operation for all colors. The toner weight Ws and the irregular toner weight Wu are arranged with respect to the photosensitive drum 21 so as to have a relationship of (Ws / Wu) <1.5.

In the above experiments, developing amount of toner to be supplied to the photosensitive drum 21 is irregular toner is 0.60 mg / cm ^2, the spherical toner was 0.52 mg / cm ^2. It is also possible to maintain the relationship of (Ws / Wu) <1.5 between the spherical toner weight Ws and the irregular toner weight Wu by changing transfer efficiency, development conditions, and the like.

  Next, the influence of the change in the rotation method of the cleaning roller 32 on the behavior of the toner remaining on the surface of the photosensitive drum 21 will be described with reference to FIGS. 4 and 5. FIG. 4 is a schematic vertical sectional partial enlarged view showing the periphery of the cleaning device, and shows a state in which the cleaning roller is rotated in a direction in which the surface moves in a direction different from the surface of the photosensitive drum, and FIG. The roller is rotated in such a direction that the surface moves in the same direction as the surface of the photosensitive drum.

  As shown in FIG. 4, when the cleaning roller 32 is rotated in such a direction that the surface at the contact point with the photosensitive drum 21 moves in a direction different from the surface of the photosensitive drum 21, the surface of the photosensitive drum 21 is cleaned by the cleaning blade 31. The toner scraped off from the toner drops onto the cleaning roller 32 and adheres to the surface of the photosensitive drum 21 again. Further, the toner directly attached to the cleaning roller 32 from the surface of the photosensitive drum 21 also adheres to the surface of the photosensitive drum 21 again in the vicinity of the cleaning blade 31. Thus, the toner cleaned from the surface of the photosensitive drum 21 is not sent out toward the screw 33 and stays between the cleaning roller 32 and the cleaning blade 31.

  As shown in FIG. 5, when the cleaning roller 32 is rotated so that the surface at the contact point with the photosensitive drum 21 moves in the same direction as the surface of the photosensitive drum 21, the surface of the photosensitive drum 21 is cleaned by the cleaning blade 31. The toner that has been scraped off or adhered directly to the cleaning roller 32 from the surface of the photosensitive drum 21 is sent out toward the screw 33 in accordance with the action of gravity and the rotation of the cleaning roller 32. The residual toner is conveyed to the outside of the housing 34 by the screw 33.

  Next, the cleaning operation by the cleaning device 30 will be described with reference to FIG. 6 in addition to FIG. 2, FIG. 4, and FIG. FIG. 6 is a graph showing a control chart of the cleaning device during cleaning and a change in the amount of residual spherical toner corresponding thereto.

  In FIG. 6, the photosensitive drum 21 is described as “drum”, and the cleaning roller 32 is described as “roller”. As for the driving method of the cleaning roller 32, “reverse direction ON” is used when the surface in contact with the photosensitive drum 21 is rotated in a direction that moves in a different direction from the surface of the photosensitive drum 21, and the surface is the surface of the photosensitive drum 21. The case of rotating in the same movement direction as “the same direction ON” is described, and the case of rotating in accordance with the rotation of the photosensitive drum 21 is described as “OFF”. Further, the change in the amount of residual spherical toner is indicated by “spherical toner weight Ws / indeterminate toner weight Wu” corresponding to FIG. The amount of toner remaining on the surface of the photosensitive drum 21 was measured using a scanning electron microscope (SEM) by collecting toner around the cleaning blade 31 at a predetermined timing when each developing device and the cleaning roller 32 are driven. .

  As shown in FIG. 6, in the image forming operation on the photosensitive drum 21, first, the photosensitive drum 21 starts to rotate, and subsequently, four developing units, namely, a black developing unit 23B, a cyan developing unit 23C, and a magenta unit. The developing device 23M and the yellow developing device 23Y are sequentially driven to form a color toner image on the surface of the intermediate transfer belt 24 (see FIG. 1).

  During the image forming operation, the control unit 60 rotates the cleaning roller 32 in such a direction that the surface at the contact point with the photosensitive drum 21 moves in a direction (reverse direction) different from the surface of the photosensitive drum 21 (see FIG. 4). . As a result, all four color toners stay around the cleaning roller 32 and the cleaning blade 31 until the image forming operation is completed. The spherical toner amount with respect to the irregular toner amount increases as the cyan, magenta, and yellow color toners are developed and reaches a maximum of 0.69 at the end of the image forming operation, but keeps 1.5 or less. Yes.

  When the image forming operations for all four colors are completed, the control unit 60 rotates the cleaning roller 32 in such a direction that the surface at the contact point with the photosensitive drum 21 moves in the same direction (same direction) as the surface of the photosensitive drum 21. (See FIG. 5). The toners of all four colors are fed toward the screw 33 by the action of gravity and the cleaning roller 32, and are conveyed to the outside of the housing 34 by the screw 33. By such a cleaning operation, the spherical toner is removed from the surface of the photosensitive drum 21 together with the irregular toner.

  Next, in the case where the cleaning operation by the cleaning device 30 is changed from that of the first embodiment, FIG. 7 is used in addition to FIGS. 2, 4 and 5 as the second embodiment of the present invention. I will explain. FIG. 7 is a graph showing a control chart of the cleaning device during cleaning and a change in the amount of residual spherical toner corresponding thereto. Note that the configuration of the cleaning device of this embodiment is the same as that of the first embodiment, so the description of the drawings and the description thereof will be omitted. The drawing method in FIG. 7 is the same as that in FIG.

  As shown in FIG. 7, in the image forming operation on the photosensitive drum 21, the photosensitive drum 21 starts to rotate, and then development of the first color black is started. When cleaning the black toner, that is, the irregular toner, the control means 60 moves the cleaning roller 32 in a direction in which the surface at the contact point with the photosensitive drum 21 moves in a direction (reverse direction) different from the surface of the photosensitive drum 21. Rotate (see FIG. 4). Thereby, the irregular toner stays around the cleaning roller 32 and the cleaning blade 31 until the cleaning of the three color toners, that is, the spherical toners, is started.

  When the development of the black toner is completed and the development of cyan, which is the first color of the three color toners, is started, the control means 60 moves the cleaning roller 32 and the photosensitive drum 21 for cleaning. Are rotated in a direction in which the surface at the contact point moves in the same direction (same direction) as the surface of the photosensitive drum 21 (see FIG. 5). Then, magenta, yellow, and spherical toner are sequentially cleaned. The spherical color toners are fed together with the irregular black toner in order of the action of gravity or the screw 33 by the cleaning roller 32, and conveyed to the outside of the housing 34 by the screw 33. The spherical toner amount relative to the irregular toner amount increases as the cyan, magenta, and yellow color toners are developed and reaches a maximum of 0.54 at the end of the image forming operation, but keeps 1.5 or less. Yes.

  When the image forming operation is completed, all the four color toners are cleaned, and the spherical toner is removed from the surface of the photosensitive drum 21 together with the irregular toner.

  Next, in the case where the cleaning operation by the cleaning device 30 is changed from that of the first and second embodiments, in addition to FIGS. 2, 4, and 5 as the third embodiment of the present invention, This will be described with reference to FIG. FIG. 8 is a graph showing a control chart of the cleaning device during cleaning and a change in the amount of residual spherical toner corresponding thereto. Note that the configuration of the cleaning device of this embodiment is the same as that of the first embodiment, so the description of the drawings and the description thereof will be omitted. The drawing method in FIG. 8 is the same as that in FIG.

  As shown in FIG. 8, in the image forming operation on the photosensitive drum 21, the photosensitive drum 21 starts to rotate, and then development of the first color black is started. When cleaning the black toner, that is, the irregular toner, the control means 60 moves the cleaning roller 32 in a direction in which the surface at the contact point with the photosensitive drum 21 moves in a direction (reverse direction) different from the surface of the photosensitive drum 21. Rotate (see FIG. 4).

  When the development of the black toner is completed and the development of cyan, which is the first color of the three color toners, is started, the controller 60 rotates the cleaning roller 32 according to the rotation of the photosensitive drum 21 (FIG. 5). The driving means 50 is controlled so as to be referred to. The spherical toner amount relative to the irregular toner amount increases as the cyan, magenta, and yellow color toners are developed and reaches a maximum of 1.28 at the end of the image forming operation, but keeps 1.5 or less. Yes.

  When the image forming operation is completed, all the four color toners are cleaned, and the spherical toner is removed from the surface of the photosensitive drum 21 together with the irregular toner.

  Next, a detailed configuration of a cleaning device according to a fourth embodiment of the present invention will be described with reference to FIG. 9 in addition to FIG. FIG. 9 is a schematic vertical sectional partial enlarged view showing the periphery of the photosensitive drum cleaning device and a schematic diagram of a control circuit.

  As shown in FIG. 9, the fourth embodiment is different from the first to third embodiments in that a bias voltage can be applied to the cleaning roller 32 that is a rotating member by using a power supply unit 70. ing. The bias voltage is 350 V when the polarity is opposite to the charging potential of the toner, and 900 V when the polarity is the same. By superimposing not only the DC voltage but also the AC voltage, it is possible to increase the efficiency of staying the toner around the cleaning roller 32 and sending it to the screw 33. Therefore, especially when the polarity is the same as the charging potential of the toner, the time from the end of the image forming operation until the cleaning roller 32 is stopped can be shortened. The power supply unit 70 is controlled by the control device 60, and the control unit 60 switches the potential on the surface of the cleaning roller 32 and the polarity thereof during the cleaning operation.

  Subsequently, the influence of the change in the bias voltage applied to the cleaning roller 32 on the behavior of the toner remaining on the surface of the photosensitive drum 21 will be described with reference to FIGS. 10 and 11. FIG. 10 is a partially enlarged schematic vertical sectional view showing the periphery of the cleaning device, and shows a state in which a bias voltage having a polarity opposite to the charging potential of the toner is applied to the cleaning roller. FIG. 11 is also the same as the charging potential of the toner. 2 shows a state in which a polar bias voltage is applied to the cleaning roller.

  As shown in FIG. 10, when a bias voltage having a polarity opposite to the charging potential of the toner is applied to the cleaning roller 32, the cleaning roller 32 and the toner attract each other. The toner scraped off falls on the cleaning roller 32 and easily adheres to the surface of the photosensitive drum 21 again. Further, the toner directly attached to the cleaning roller 32 from the surface of the photosensitive drum 21 does not leave the surface of the cleaning roller 32. In this way, even when the cleaning roller 32 is always rotated in such a direction that the surface at the contact point with the photosensitive drum 21 moves in the same direction as the surface of the photosensitive drum 21, the surface of the photosensitive drum 21. The toner cleaned from is not sent out toward the screw 33 and is strongly subjected to the action of staying around the cleaning roller 32.

  As shown in FIG. 11, when a bias voltage having the same polarity as the charging potential of the toner is applied to the cleaning roller 32, the cleaning roller 32 and the toner repel each other. The toner scraped off or directly attached to the cleaning roller 32 from the surface of the photosensitive drum 21 is easily sent out toward the screw 33 in accordance with the action of gravity or the rotation of the cleaning roller 32. The residual toner is conveyed to the outside of the housing 34 by the screw 33.

  Next, the cleaning operation by the cleaning device 30 will be described with reference to FIG. 12 in addition to FIGS. FIG. 12 is a graph showing a control chart of the cleaning device during cleaning and a change in the amount of residual spherical toner corresponding thereto. The drawing method of FIG. 12 is basically the same as the drawing method of FIG. 6 used in the description of the first embodiment, but the cleaning roller 32 is replaced with the rotation control of the cleaning roller 32. The control chart of the bias voltage applied to is drawn. The cleaning roller 32 always rotates in such a direction that the surface at the contact point with the photosensitive drum 21 moves in the same direction as the surface of the photosensitive drum 21.

  As shown in FIG. 12, in the image forming operation on the photosensitive drum 21, first, the photosensitive drum 21 starts to rotate, and subsequently, four developing devices, ie, a black developing device 23B, a cyan developing device 23C, and magenta. The developing device 23M and the yellow developing device 23Y are sequentially driven to form a color toner image on the surface of the intermediate transfer belt 24 (see FIG. 1).

  During the image forming operation, the control unit 60 applies a bias voltage having a polarity opposite to the charging potential of the toner to the cleaning roller 32 (see FIG. 10). As a result, all four colors of toner are attracted to the cleaning roller 32 and stay around the cleaning roller 32 and the cleaning blade 31 until the image forming operation is completed. The spherical toner amount with respect to the irregular toner amount increases as the cyan, magenta, and yellow color toners are developed and reaches a maximum of 0.69 at the end of the image forming operation, but keeps 1.5 or less. Yes.

  When the image forming operations for all four colors are completed, the control unit 60 applies a bias voltage having the same polarity as the charging potential of the toner to the cleaning roller 32 (see FIG. 11). The toners of all four colors repel the cleaning roller 32, are sent out toward the screw 33 in accordance with the action of gravity and the rotation of the cleaning roller 32, and are conveyed outside the housing 34 by the screw 33. By such a cleaning operation, the spherical toner is removed from the surface of the photosensitive drum 21 together with the irregular toner. When the rotation of the cleaning roller 32 is stopped, the bias voltage application to the cleaning roller 32 is also stopped.

  Next, a case where the cleaning operation by the cleaning device 30 is changed from that of the fourth embodiment will be described as a fifth embodiment of the present invention with reference to FIG. 13 in addition to FIGS. 9 to 11. FIG. 13 is a graph showing a control chart of the cleaning device during cleaning and a change in the amount of residual spherical toner corresponding thereto. Note that the configuration of the cleaning device of this embodiment is the same as that of the fourth embodiment, so the description of the drawings and the description thereof will be omitted. The drawing method of FIG. 13 is also the same as that of FIG.

  As shown in FIG. 13, in the image forming operation on the photosensitive drum 21, the photosensitive drum 21 starts to rotate, and then development of the first color, black, is started. When cleaning the black toner, that is, the irregular toner, the control means 60 applies a bias voltage having a polarity opposite to the charging potential of the toner to the cleaning roller 32 (see FIG. 10). Thereby, the irregular toner stays around the cleaning roller 32 and the cleaning blade 31 until the cleaning of the three color toners, that is, the spherical toners, is started.

  When the development of the black toner is completed and the development of the first color cyan among the three color toners is started, the control means 60 sends the toner charging potential to the cleaning roller 32 for cleaning. A bias voltage having the same polarity as that of the first electrode is applied (see FIG. 11). Then, magenta, yellow, and spherical toner are sequentially cleaned. The spherical color toners, together with the irregularly shaped black toner, are sequentially repelled by the action of gravity or the cleaning roller 32 and sent toward the screw 33, and are conveyed outside the housing 34 by the screw 33. The spherical toner amount relative to the irregular toner amount increases as the cyan, magenta, and yellow color toners are developed and reaches a maximum of 0.54 at the end of the image forming operation, but keeps 1.5 or less. Yes.

  When the image forming operation is completed, all the four color toners are cleaned, and the spherical toner is removed from the surface of the photosensitive drum 21 together with the irregular toner.

  In this manner, in the toner cleaning device 30 that remains on the surface of the photosensitive drum 21 that is an image carrier that repeats the image forming process for each of a plurality of colors, the toner that contacts the photosensitive drum 21 and adheres to the surface is removed. A cleaning blade 31 that is scraped off, a cleaning roller 32 that is provided upstream of the cleaning blade 31 in the rotational direction of the photosensitive drum 21 and that contacts the photosensitive drum 21, and a driving unit 50 that rotates the cleaning roller 32. And a control means 60 for controlling the driving means 50. The control means 60 first cleans the amorphous toner out of the plurality of irregular and spherical toners. Since the rotation method of the cleaning roller 32 is selected, the irregular toner is The period allowed to stay in the neighborhood of Gurora 32 and the cleaning blade 31 can be selected arbitrarily. This makes it possible to mix and clean a suitable amount of irregular toner when cleaning the spherical toner. Therefore, it is possible to obtain a suitable cleaning performance for the toner remaining on the surface of the photosensitive drum 21 without impairing a clear and high-quality image obtained by using a spherical toner having a small diameter and a uniform shape and size. Can do.

  Further, the control means 60 moves the cleaning roller 32 in a direction in which the surface at the contact point with the photosensitive drum 21 is different from the surface of the photosensitive drum 21 until the image forming operation for all the colors on the photosensitive drum 21 is completed. When the image forming operation for all colors is completed, the surface at the contact point with the photosensitive drum 21 is rotated in the same direction as the surface of the photosensitive drum 21, so that the image forming operation is performed during the image forming operation. The toner remaining on the surface of the photosensitive drum 21 can be retained around the cleaning roller 32 and the cleaning blade 31 until the image forming operation for all colors is completed. As a result, it is possible to simultaneously clean all of the irregular and spherical toners remaining on the surface of the photosensitive drum 21 for the irregular and spherical toners of different colors. Therefore, the cleaning performance of the spherical toner using the irregular toner is improved.

  Further, the control means 60 rotates the cleaning roller 32 in such a direction that the surface at the contact point with the photosensitive drum 21 moves in a direction different from the surface of the photosensitive drum 21 during cleaning of the irregular shaped toner. At the time of cleaning, the surface at the contact point with the photosensitive drum 21 is rotated so that the surface moves in the same direction as the surface of the photosensitive drum 21. Therefore, the amorphous toner is removed from the cleaning roller 32 and the cleaning blade until the spherical toner starts cleaning. In the case of cleaning a plurality of different color spherical toners, the spherical toners can be sequentially discharged together with the irregular toners for each color. This makes it possible to reduce the spherical toner of the previously developed color existing around the cleaning roller 32 and the cleaning blade 31 as much as possible when cleaning the spherical toner of the developed color later. Therefore, the cleaning performance of the spherical toner is further improved.

  The cleaning roller 32 rotates according to the rotation of the photosensitive drum 21 when the surface at the contact point with the photosensitive drum 21 rotates in the direction of moving in the same direction as the surface of the photosensitive drum 21. The time for rotating the cleaning roller 32 can be shortened. As a result, the energy consumed by the drive means 50 can be reduced, so that the cleaning device 30 with energy saving can be obtained. In addition, since it is not necessary to provide the drive means 50 with a function of switching the rotation direction of the cleaning roller 32, the cost of the cleaning device 30 can be reduced.

  Further, a power supply unit 70 for applying a bias voltage to the cleaning roller 32 is provided, and the control unit 60 controls the power supply unit 70 to switch the bias voltage applied to the cleaning roller 32 during the cleaning operation. The property of attracting each other when the toners are of opposite polarity and repelling each other when they are of the same polarity can be used for toner cleaning. Accordingly, it is possible to increase the action of retaining the irregular shaped toner around the cleaning roller 32 and the cleaning blade 31 until the spherical toner starts to be cleaned, and to suppress the irregular shaped toner from being scattered to other portions. It becomes possible. Therefore, when cleaning the spherical toner, it becomes possible to mix more irregular toner and clean it. As a result, the cleaning performance for the toner remaining on the surface of the photosensitive drum 21 can be further improved.

  Further, the control means 60 applies a voltage having a polarity opposite to that of the toner to the cleaning roller 32 until the image forming operation for all the colors on the photosensitive drum 21 is completed, and cleaning is performed from the end of the image forming operation for all the colors. Since the voltage having the same polarity as the toner is applied until the roller 32 is stopped, the toner remaining on the surface of the photosensitive drum 21 during the image forming operation is used for the cleaning roller 32 until the image forming operation for all the colors is completed. It is possible to make it easier to stay around the cleaning blade 31. As a result, the effect of simultaneously cleaning all the amorphous and spherical toners remaining on the surface of the photosensitive drum 21 is enhanced, and the cleaning performance of the spherical toner using the irregular toner is further improved.

  Further, since the control means 60 applies a voltage having a polarity opposite to that of the toner when cleaning the irregular toner and a voltage having the same polarity as that of the toner when cleaning the spherical toner, the control means 60 cleans the spherical toner. It is possible to enhance the effect of retaining the irregular toner around the cleaning roller 32 and the cleaning blade 31 until the start of the toner and the effect of sequentially discharging the spherical toner together with the irregular toner for each color. As a result, the effect of removing the spherical toner of the color previously developed on the surface of the photosensitive drum 21 from the periphery of the cleaning roller 32 and the cleaning blade 31 before starting the cleaning of the spherical toner of the subsequent color is enhanced. The toner cleaning performance is further improved.

  Since the irregular toner is a black toner and the spherical toner is a toner other than black, a spherical toner having a small diameter and a uniform shape and size can be used as the color toner. As a result, a clearer and higher quality color image can be obtained, and the cleaning performance can be improved by the irregular black toner.

  In the image forming operation for all colors, the spherical toner weight Ws and the irregular toner weight Wu remaining between the cleaning blade 31 and the cleaning roller 32 in the vicinity of the surface of the photosensitive drum 21 are (Ws / Wu). ) Since the cleaning blade 31 and the cleaning roller 32 are arranged so as to have a relationship of <1.5, the surface of the photosensitive drum 21 is used even when a large amount of spherical toner is used to form a clear and high-quality image. Therefore, it is possible to maintain a suitable amount of irregularly shaped toner for cleaning the toner remaining on the toner. Accordingly, it is possible to obtain a clear and high-quality image, and to suppress the wasteful wasted toner, and to obtain the cleaning device 30 in consideration of resources and the environment at a low running cost.

  In the present invention, since the cleaning device 30 is mounted on the image forming apparatus 1, the toner remaining on the surface of the photosensitive drum 21 without impairing the clear and high-quality image obtained by using the spherical toner. In contrast, it is possible to obtain a high-performance image forming apparatus 1 that can maintain a suitable cleaning performance and is low in running cost and in consideration of resources and the environment.

  Although the embodiments of the present invention have been described above, the scope of the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the invention.

  The present invention can be used in a cleaning apparatus provided for an image carrier that repeats an image forming process of development, transfer, and cleaning for each color using a plurality of toners having different shapes of irregular and spherical shapes.

It is a model vertical section left side view showing a printer carrying a cleaning device according to an embodiment of the present invention. It is the model vertical cross-section partial enlarged view which shows the cleaning device periphery which concerns on the 1st Embodiment of this invention, and the schematic of a control circuit. It is a graph which shows the influence which the amount of spherical toner has on the minimum linear pressure which can be cleaned. FIG. 3 is a partially enlarged view of a schematic vertical cross section similar to FIG. 2, showing a state where the cleaning roller is rotated in a predetermined direction. FIG. 5 is a partially enlarged schematic vertical cross-sectional view similar to FIG. 2, showing a state where the cleaning roller is rotated in a direction different from that in FIG. 4. 4 is a control chart of the cleaning device according to the first exemplary embodiment of the present invention and a graph showing a change in a residual spherical toner amount corresponding to the control chart. 7 is a control chart of a cleaning device according to a second embodiment of the present invention and a graph showing changes in residual spherical toner amount corresponding to the control chart. It is a graph which shows the control chart of the cleaning apparatus which concerns on the 3rd Embodiment of this invention, and the change of the amount of residual spherical toner corresponding to this. It is the model vertical cross-section partial enlarged view which shows the periphery of the cleaning apparatus which concerns on the 4th Embodiment of this invention, and the schematic of a control circuit. FIG. 10 is a schematic enlarged vertical sectional view similar to FIG. 9 showing a state in which a bias voltage having a polarity opposite to the charging potential of the toner is applied to the cleaning roller. FIG. 10 is a schematic enlarged vertical sectional view similar to FIG. 9 and shows a state where a bias voltage having the same polarity as the charging potential of the toner is applied to the cleaning roller. It is a graph which shows the control chart of the cleaning apparatus which concerns on the 4th Embodiment of this invention, and the change of the amount of residual spherical toner corresponding to this. It is a graph which shows the control chart of the cleaning apparatus which concerns on the 5th Embodiment of this invention, and the change of the amount of residual spherical toner corresponding to this.

Explanation of symbols

1 Printer (image forming device)
20 Image forming unit 21 Photosensitive drum (image carrier)
23 Developing device 23a Rotary rack 23B Black developing device 23C Cyan developing device 23M Magenta developing device 23Y Yellow developing device 24 Intermediate transfer belt 30 Cleaning device 31 Cleaning blade 32 Cleaning roller (rotating member)
33 Screw 34 Housing 50 Drive means 60 Control means 70 Power supply

Claims (8)

An image forming apparatus,
An image carrier that rotates in a predetermined rotation direction about a horizontal axis;
A developing device provided around the image carrier , containing a plurality of different color toners, and forming a toner image of each color on the image carrier;
A cleaning device provided around the image carrier and for cleaning toner remaining on the image carrier after the toner image is transferred ;
With
The cleaning device includes:
A blade that contacts the image carrier and scrapes off toner adhering to the surface;
A below the blade, said a upstream side of the rotational direction than the blade, provided at a position for receiving the toner to fall scraped off by the blade, in contact with said image bearing member, and the horizontal axis A rotating member that rotates about a parallel axis ;
Have
Of the plurality of different color toners, the first color toner is an irregular toner, and the second color toner is a spherical toner,
Perform toner image formation, transfer, and cleaning image formation process for each color,
Starting the image forming process from the first color;
Before SL from the cleaning of the first color toner to the start of the image forming process of at least the second color, rotating the rotary member in the same direction as the direction of rotation,
All from the image forming process at the end of the color until stopping the rotation of the image bearing member, an image forming apparatus characterized by rotating the rotating member in the direction of the rotational direction opposite. 2. The image forming apparatus according to claim 1, wherein when the second color toner is cleaned, the rotation member is rotated in the same direction as the rotation direction . 2. The image forming apparatus according to claim 1, wherein when the second color toner is cleaned, the rotating member is rotated in a direction opposite to the rotating direction . 4. The image forming apparatus according to claim 1, wherein the rotating member rotates in accordance with the rotation of the image carrier when rotating in a direction opposite to the rotating direction . 5. An image forming apparatus,
An image carrier that rotates in a predetermined rotation direction about a horizontal axis;
A developing device provided around the image carrier , containing a plurality of different color toners, and forming a toner image of each color on the image carrier;
A cleaning device provided around the image carrier and for cleaning toner remaining on the image carrier after the toner image is transferred ;
With
The cleaning device includes:
A blade that contacts the image carrier and scrapes off toner adhering to the surface;
A below the blade, said a upstream side of the rotational direction than the blade, provided at a position for receiving the toner to fall scraped off by the blade, in contact with said image bearing member, and the horizontal axis A rotating member that rotates about a parallel axis ;
A power supply for applying a bias voltage to the rotating member ;
Have
Of the plurality of different color toners, the first color toner is an irregular toner, and the second color toner is a spherical toner,
Perform toner image formation, transfer, and cleaning image formation process for each color,
Starting the image forming process from the first color;
Rotating the rotating member in a direction opposite to the rotating direction ;
A voltage having a polarity opposite to that of the toner is applied to the rotating member from the time of cleaning the toner of the first color to at least the start of the image forming process of the second color ;
An image forming apparatus, wherein a voltage having the same polarity as that of toner is applied to the rotating member from the end of the image forming process for all colors to the stop of rotation of the image carrier. 6. The image forming apparatus according to claim 5, wherein a voltage having a polarity opposite to that of the toner is applied to the rotating member when cleaning the toner of the second color . 6. The image forming apparatus according to claim 5, wherein a voltage having the same polarity as the toner is applied to the rotating member when cleaning the second color toner. 8. The image formation according to claim 1 , wherein the toner of the first color is a black toner, and the toner other than the toner of the first color is a spherical toner. apparatus.

Images