JP6840490B2 - Image forming device - Google Patents

Description

The present invention relates to an image forming apparatus such as a copier, a facsimile, or a printer using an electrophotographic method or an electrostatic recording method.

In an image forming apparatus using an electrophotographic method, when paper dust generated from paper, which is often used as a transfer material to which an image is transferred, adheres to an image carrier such as a photoconductor, it may appear as streaks on the image. Image defects such as white spots appearing may occur. Therefore, it is desired to remove the paper dust so that the paper dust does not adhere to the image carrier.

Therefore, a configuration has been proposed in which PFA is used on the surface of the register roller provided in the transfer path of the transfer material, the resist roller is rubbed and charged by friction with the paper, and the paper dust is electrostatically adsorbed on the register roller and collected. (Patent Document 1).

JP-A-2002-1549999

However, in the above-mentioned conventional configuration, since the potential difference due to the rubbing charge between the resist roller and the paper is used, the potential generated depends on the temperature and humidity in which the image forming apparatus is installed, the transport state of the transfer material, and the like. It becomes unstable. When this potential becomes unstable, the collection of paper dust also becomes unstable, so that it may not be possible to sufficiently suppress the adhesion of paper dust to the image carrier.

On the other hand, it is conceivable to add a paper dust removing mechanism for removing paper dust on the photoconductor in a cartridge holding the photoconductor or the like. However, in this method, the cartridge becomes large and the cost of the cartridge as a replacement unit increases. Further, when the image forming apparatus has a plurality of cartridges, a paper dust removing apparatus is provided in the cartridge arranged at the most upstream of the image forming process in order to prevent the paper dust from adhering to the photoconductors of all the cartridges. Can be considered. In that case, since the cartridge configuration differs depending on the presence or absence of the paper dust removing device, the manufacturing equipment cannot be shared, which leads to an increase in the manufacturing equipment cost.

Therefore, an object of the present invention is to provide an image forming apparatus capable of stably suppressing the adhesion of paper dust to the image carrier regardless of the usage environment of the apparatus and the transport state of the transfer material. ..

The above object is achieved by the image forming apparatus according to the present invention. In summary, the present invention applies to an image forming portion that forms a toner image on an image carrier charged to a predetermined polarity, and a voltage opposite to the predetermined polarity is applied to the transfer portion to transfer from the image carrier. a transfer unit for transferring the toner image to the timber, a first power supply for outputting voltages of opposite polarity from the predetermined polarity, upstream of the transfer portion in the conveying direction of the transfer material is conveyed to the transfer section provided, in contact with the surface on which the toner image of the transfer material is transferred to transport the transfer material, and a foreign material from the transfer material by the voltage of the opposite polarity is applied by said first power supply A transfer roller to be removed, an opposing roller that is in contact with a surface opposite to the surface on which the toner image of the transfer material is transferred, transfers the transfer material together with the transfer roller, and is electrically grounded. A second power source that outputs a voltage having a predetermined polarity and a second power source that is provided upstream of the transfer unit and downstream of the transfer roller in the transfer direction and faces the surface on which the toner image of the transfer material is transferred, and the first. the second power supply has a discharging means for the toner image of the transfer material by the voltage of the predetermined polarity is applied to remove the electric load of the surface to be transferred, a voltage is applied, the transfer Only the transport roller is provided as a member for removing foreign matter from the transfer material transported to the unit, and the static elimination means includes a static elimination needle to which a voltage is applied from the second power source. It is an image forming apparatus characterized by removing an electric charge on a surface on which a toner image of the transfer material is transferred without coming into contact with the transfer material.
According to another aspect of the present invention, an image forming portion that forms a toner image on an image carrier charged to a predetermined polarity and a voltage having a polarity opposite to that of the predetermined polarity are applied from the image carrier at the transfer portion. A transfer means for transferring the toner image to the transfer material, a power source for outputting a voltage having a polarity opposite to the predetermined polarity, and an upstream of the transfer unit in the transfer direction of the transfer material to be transferred to the transfer unit are provided. A transfer roller that conveys the transfer material in contact with the surface on which the toner image of the transfer material is transferred, and removes foreign matter from the transfer material by applying a voltage of the opposite polarity from the power supply. , The transfer material is conveyed together with the transfer roller in contact with the surface opposite to the surface on which the toner image of the transfer material is transferred, and the electrically grounded facing roller and the transfer direction. A static elimination means provided upstream of the transfer unit and downstream of the transfer roller, which faces the surface on which the toner image of the transfer material is transferred and removes charges on the surface on which the toner image of the transfer material is transferred. Only the transport roller is provided as a member that removes foreign matter from the transfer material that is transported to the transfer unit by having a voltage applied, and the static elimination means is electrically grounded. Provided is an image forming apparatus comprising a static eliminating needle to be provided, wherein the static eliminating needle removes an electric charge on a surface on which a toner image of the transfer material is transferred without contacting the transfer material.

According to the present invention, it is possible to stably suppress the adhesion of paper dust to the image carrier regardless of the usage environment of the apparatus and the transport state of the transfer material.

It is the schematic sectional drawing of the image forming apparatus. It is a schematic cross-sectional view in the vicinity of a paper dust removing mechanism. It is the schematic sectional drawing of another example of an image forming apparatus. It is a schematic cross-sectional view in the vicinity of a paper dust removing mechanism. It is the schematic sectional drawing of another example of an image forming apparatus. It is the schematic sectional drawing of another example of an image forming apparatus.

Hereinafter, the image forming apparatus according to the present invention will be described in more detail with reference to the drawings.

[Example 1]
1. 1. Overall Configuration and Operation of the Image Forming Device FIG. 1 is a schematic cross-sectional view of the image forming device 100 of the present embodiment. The image forming apparatus 100 of this embodiment is a tandem type color laser printer capable of forming a full-color image by using an electrophotographic process. In particular, the image forming apparatus 100 of this embodiment employs an ETB method in which the transfer material is conveyed by a belt.

The image forming apparatus 100 has the first, second, third, and fourth image forming units SY, SM, which form images of each color of yellow, magenta, cyan, and black as a plurality of image forming units (stations), respectively. Has SC and SK. For elements having the same or corresponding functions or configurations in these four image forming units SY, SM, SC, and SK, Y, M, C, and K at the end of the code indicating that they are elements for any of the colors. May be omitted for general explanation. The image forming unit S is composed of a photoconductor 11, a charging device 12, an exposure device 13, a developing device 14, a transfer roller 15, and the like, which will be described later.

The rotatable drum-shaped photoconductor (electrophotograph photoconductor) 11 is rotationally driven in the direction of arrow R1 (clockwise) in the drawing. The surface of the rotating photoconductor 11 is charged to a predetermined potential of a predetermined polarity (positive electrode property in this embodiment) by a corona charging device (here, also simply referred to as a “charging device”) 12 as a charging means. .. The surface of the charged photoconductor 11 is scanned and exposed by the exposure device (scanner unit) 13 with a laser beam corresponding to the image information, and an electrostatic latent image (electrostatic image) is formed on the photoconductor 11. In this embodiment, the charging device 12 and the exposure device 13 constitute an electrostatic image forming means.

The electrostatic latent image formed on the photoconductor 11 is developed (visualized) by the developing device 14 using toner as a developer, and a toner image is formed on the photoconductor 11. The developing apparatus 14 has a developing roller as a developing agent carrier that carries the developing agent and conveys it to a portion (development portion) facing the photoconductor 11. During the developing process, the developing roller has a predetermined development bias (development). Voltage) is applied. As a result, due to the potential difference between the photoconductor 11 and the developing roller, toner is supplied from the developing roller to the photoconductor 11 according to the electrostatic latent image on the photoconductor 11, and a toner image is formed on the photoconductor 11. In this embodiment, the exposed portion on the photoconductor 11 whose absolute potential value is lowered by being exposed after being uniformly charged has the same polarity as the charging polarity of the photoconductor 11 (positive electrode property in this embodiment). ) Is charged with toner.

A transfer belt 20 composed of an endless belt as a transfer material carrier is arranged so as to face each photoconductor 11. The transfer belt 20 is stretched between the drive roller 21 and the tension roller 22, and the drive roller 21 is rotationally driven to rotate (rotate) in the direction of arrow R2 (counterclockwise) in the drawing. On the inner peripheral surface side of the transfer belt 20, a transfer roller 15 as a transfer means is arranged corresponding to each photoconductor 11. The transfer roller 15 is pressed (urged) toward the photoconductor 11 via the transfer belt 20 to form a transfer portion N in which the photoconductor 11 and the transfer belt 20 come into contact with each other.

The toner image formed on the photoconductor 11 as described above is transferred to the transfer material (sheet) P supported and conveyed on the transfer belt 20 by the action of the transfer roller 15 in the transfer unit N. During the transfer step, a transfer bias (transfer voltage) having a polarity opposite to the charge polarity (normal charge polarity) of the toner during development (negative electrode property in this embodiment) is applied to the transfer roller 15. For example, when forming a full-color image, images of each color of yellow, magenta, cyan, and black formed on each photoconductor 11 are sequentially transferred so as to be superimposed on the transfer material P supported on the transfer belt 20. ..

The transfer material P is stored in a cassette 31 as a storage unit. The transfer material P in the cassette 31 is picked up by the feeding roller 32 and sent out to the transport path 33. The transfer material P sent out to the transfer path 33 is conveyed to the transfer belt 20 by the transfer roller pair 1 as the transfer means. Further, the transfer material P transferred to the transfer belt 20 by the transfer roller pair 1 is statically eliminated by the static elimination device 2 as a static elimination means. The paper dust removing mechanism 10 including the transport roller pair 1 and the static elimination device 2 will be described in detail later.

The transfer material P to which the toner image is transferred is separated from the transfer belt 20 and conveyed to the heat fixing device 18 as a fixing means. Then, the transfer material P is discharged to an external discharge tray 19 of the apparatus main body 110 of the image forming apparatus 100 after the toner image is fixed (melted and fixed) by being heated and pressurized by the heat fixing device 18. Toner.

The image forming apparatus 100 of this embodiment employs a photoconductor cleanerless configuration, and the toner (transfer residual toner) remaining on the surface of the photoconductor 11 after the transfer step is recovered by the developing apparatus 14. That is, the transfer residual toner on the photoconductor 11 is charged to a normal charging polarity when passing through the charged portion of the photoconductor 11 by the charging device 12. Then, when the transfer residual toner passes through the developing unit, it is transferred to the developing roller due to the potential difference between the photoconductor 11 and the developing roller of the developing device 14, and is collected by the developing device 14. This can be done at the same time as developing the electrostatic latent image on the photoconductor 11. That is, due to the potential difference between the photoconductor 11 and the developing roller, toner is transferred from the developing roller to the image portion of the electrostatic latent image on the photoconductor 11, and the transfer residual toner adhering to the non-image portion is transferred to the developing roller. Transfer.

In this embodiment, in each image forming unit S, the photoconductor 11 and the charging device 12 and the developing device 14 as process means acting on the photoconductor 11 are integrally detachable from the device main body 110. Consists of.

2. 2. Paper dust removing mechanism Next, the paper dust removing mechanism 10 in this embodiment will be described. FIG. 2 is a schematic cross-sectional view of the vicinity of the paper dust removing mechanism 10 in this embodiment.

Here, the surface of the transfer material P on the side where the toner image is transferred immediately after passing through the paper dust removing mechanism 10 is called an "image forming surface", and the surface of the transfer material P opposite to the image forming surface is ". Called "back side". Further, here, it is assumed that the transfer material P is paper. This is because paper is often used as the transfer material P in the electrophotographic image forming apparatus 100, and in that case, the problem due to the paper dust generated from the transfer material P becomes remarkable. The image forming apparatus 100 can form and output an image as the transfer material P not only on paper but also on, for example, a plastic sheet or cloth.

When the transfer material P is transported, the transfer material P and the rollers for transporting the transfer material P and the constituent members of the transport path rub against each other, so that the pulp fibers containing cellulose as a main component are peeled from the transfer material P. And paper dust is generated. The paper dust may contain a filler peeled off from the transfer material P. In this embodiment, most of the paper dust is positively charged by rubbing against a roller for transporting the transfer material P or a transport path.

The transfer roller pair 1 is composed of a transfer roller 1a that contacts the image forming surface of the transfer material P and an opposing roller 1b that is arranged to face the transfer roller 1a and contacts the back surface of the transfer material P. In this embodiment, the transport roller 1a and the opposing roller 1b are pressed (biased) against each other, and each is rotationally driven.

The transport roller 1a is made of a conductive member. As the transport roller 1a, a roller having a surface layer made of conductive rubber or plastic formed on the outer periphery of the core metal (core material) can be used. A first power source (paper dust removing power source) 5 as a paper dust removing voltage applying means is connected to the transport roller 1a. The first power supply 5 applies a first voltage (paper dust removing voltage) of −300 V, which is a DC voltage having a polarity opposite to the charging polarity of the paper dust, to the transport roller 1a. As a result, the surface of the transport roller 1a is negatively charged. Further, the opposing roller 1b is made of a conductive member. As the opposing roller 1b, a metal roller, a roller having a surface layer made of conductive rubber or plastic on the outer periphery of the core metal (core material), or the like can be used. The opposing roller 1b is connected to GND (electrically grounded).

The opposing roller 1b is connected to the GND by providing a sufficient potential difference between the conveying roller 1a and the opposing roller 1b, and paper dust is transferred from the transfer material P between the conveying roller 1a and the opposing roller 1b. This is to generate an electric field in the direction of urging the transport roller 1a. If a sufficient potential difference can be provided between the transport roller 1a and the opposing roller 1b, the opposing roller 1b does not necessarily have to be connected to the GND.

Further, the charging polarity of the paper dust that reaches the transport roller pair 1 is due to the paper dust adhering to the photoconductor 11 by adopting the transfer material P (paper) mainly used in the image forming apparatus 100. The problem can often be suppressed. Alternatively, a transfer material P of a specific type (attributes such as plain paper, thick paper, coated paper, manufacturer, product number, etc.) for which it is desired to suppress the problem caused by the adhesion of paper dust to the photoconductor 11 is adopted. You can also do it.

Positively charged paper adhering to the image forming surface of the transfer material P due to the electric field generated between the transfer rollers 1a and the opposing rollers 1b when the transfer material P passes between the transfer rollers 1: 1. The powder is attracted to the transport roller 1a and removed from the transfer material P. The positively charged paper dust that has moved onto the transport roller 1a is scraped off from the surface of the rotating transport roller 1a by the sheet 3 as a removing member arranged in contact with the surface of the transport roller 1a and collected. It is housed in the tray 4 as a container. Further, at this time, the transfer material P is negatively charged by the electric field generated between the transport roller 1a and the opposing roller 1b.

The static elimination device 2 is arranged downstream of the transfer roller pair 1 in the transfer direction of the transfer material P so as to face the image forming surface of the transfer material P. The static eliminator 2 includes a holder 2a made of an electrically insulating member as a support member and a static eliminator needle 2b as a static eliminator made of a conductive member. In this embodiment, the static elimination needle 2b is arranged at a position sufficiently close to the transfer material P so that the electric charge on the transfer material P can be removed. The static elimination needle 2b can also be arranged at a position where it can come into contact with the transfer material P. A second power source (static elimination power source) 6 as a static elimination voltage applying means is connected to the static elimination needle 2b. The second power supply 6 applies a second voltage (static elimination voltage) of + 300 V, which is a DC voltage having the opposite polarity to the voltage applied to the transfer roller 1a by the first power supply 5, to the static elimination needle 2b.

The transfer material P charged negatively when passing through the transport roller pair 1 is statically eliminated by the static elimination needle 2b when passing through the position facing the static elimination device 2.

The static eliminator needle 2b is connected to the second power source 6 by providing a sufficient potential difference between the transfer material P and the static eliminator needle 2b, and between the transfer material P and the static eliminator needle 2b. This is to generate an electric field in the direction of attenuating the upper charge. If a sufficient potential difference can be provided between the transfer material P and the static elimination needle 2b, the static elimination needle 2b does not necessarily need to be applied with a voltage from the power source, and even if it is connected to GND (electrically grounded), for example. Good.

Here, the static eliminator 2 is not limited to completely removing the electric charge on the transfer material P, and as will be described later, the transfer material is sufficiently capable of suppressing defects in the transfer unit N to an acceptable level. It suffices if at least a part of the electric charge on P can be removed.

In this embodiment, the paper dust removing mechanism 10 is provided by a transport roller pair 1, a static eliminator 2, a sheet 3, a tray 4, a power supply 5, 6 and the like arranged in a transport path 33 from the feed roller 32 to the transfer belt 20. Is configured.

The transport roller pair 1 may have a function other than the function of transporting the transfer material P and the function of removing paper dust. For example, a resist roller pair may be used to more accurately align the position of the toner image with the position of the transfer material P. The resist roller pair temporarily stops the transfer of the transfer material P between the feed roller 32 and the transfer belt 20 and then feeds the transfer material P again at the same timing, or finely adjusts the skew and the transfer speed of the transfer material P. .. The transport roller pair 1 may also serve as the function of the resist roller pair. That is, the transfer roller 1a may also function as a resist roller used for adjusting the transfer timing or transfer posture of the transfer material P.

As described above, in this embodiment, the image forming apparatus 100 is provided upstream of the transfer unit N in the transfer direction of the transfer material P to be transferred to the transfer unit N, and the surface on which the toner image of the transfer material P is transferred. It has a transport roller 1a that transports the transfer material P in contact with. Further, the image forming apparatus 100 has a power supply 5 that applies a voltage to the transport roller 1a. Further, the image forming apparatus 100 is provided upstream of the transfer unit N and downstream of the transfer roller 1a in the transfer direction, and has a static elimination means 2 for removing at least a part of electric charges on the transfer material. Then, at least a part of the electric charge on the transfer material P transferred by the transfer roller 1a to which the voltage is applied from the power source 5 is removed by the static elimination means 2.

According to this embodiment, the paper dust can be removed from the image forming surface of the transfer material P not by the potential difference due to the triboelectric charge between the transfer roller 1a and the transfer material P but by the potential difference due to the voltage applied to the transfer material P. It will be possible. As a result, the paper dust can be stably removed regardless of the usage environment and the transport state of the transfer material P, and the image defect due to the paper dust adhering to the photoconductor 11 can be stably suppressed. .. Further, since it is not necessary to have a device for removing paper dust on the photoconductor 11 in the cartridge 17, it is possible to reduce the size and capacity of the cartridge 17. Further, since the cartridges 17Y, 17M, 17C, and 17K for each color can have the same configuration, the manufacturing equipment can be shared and the manufacturing cost can be reduced.

In particular, in the image forming apparatus 100 having a photoconductor cleanerless configuration, it is necessary to suppress the adhesion of paper dust to the photoconductor 11 as compared with the configuration provided with the photoconductor cleaning device for removing the transfer residual toner from the photoconductor 11. Is high. Therefore, in the image forming apparatus 100 having the photoconductor cleanerless configuration, the paper dust adheres to the photoconductor 11 by the paper dust removing mechanism 10 as compared with the configuration provided with the photoconductor cleaning device for removing the transfer residual toner from the photoconductor 11. This has a great effect of suppressing image defects.

Further, according to the present embodiment, the transfer material P charged by the transfer roller 1a is statically eliminated by the static elimination device 2, thereby suppressing image defects in the transfer portion N due to the transfer material P being charged. be able to. An example of the image defect in the transfer unit N is that the toner image on the photoconductor 11 or the transfer material P is disturbed by the electric discharge between the photoconductor 11 and the transfer material P.

[Example 2]
Next, other examples of the present invention will be described. In this embodiment, elements having the same or corresponding functions or configurations as those in the first embodiment are designated by the same reference numerals, and detailed description thereof will be omitted.

1. 1. Overall Configuration and Operation of the Image Forming Device FIG. 3 is a schematic cross-sectional view of the image forming device 100 of the present embodiment. The image forming apparatus 100 of this embodiment employs an intermediate transfer belt (ITB) method.

In this embodiment, the image forming unit S is composed of a photoconductor 11 as a first image carrier, a charging device 12, an exposure device 13, a developing device 14, a primary transfer roller 15 described later, and the like. Further, in this embodiment, both the charging polarity of the photoconductor 11 and the normal charging polarity of the toner are negative electrodes, and a toner image is formed by the reverse development method. That is, the negatively charged toner adheres to the exposed portion on the photoconductor 11 whose absolute potential value is lowered by being exposed after being uniformly charged to the negative electrode.

The image forming apparatus 100 of this embodiment has an intermediate transfer belt 40 composed of an endless belt as a second image carrier, which is arranged so as to face each photoconductor 11. The intermediate transfer belt 40 is an example of an intermediate transfer body that conveys a toner image transferred from another image carrier provided in the image forming unit to the transfer unit. The intermediate transfer belt 40 is stretched on a drive roller (secondary transfer opposed roller) 41, a tension roller 42, and an idler roller 43, and the drive roller 41 is rotationally driven to drive in the direction of arrow R3 (counterclockwise) in the drawing. ) To rotate (move around). On the inner peripheral surface side of the intermediate transfer belt 40, a primary transfer roller 15 as a primary transfer means is arranged corresponding to each photoconductor 11. The primary transfer roller 15 is pressed (urged) toward the photoconductor 11 via the intermediate transfer belt 40 to form a primary transfer unit N1 in which the photoconductor 11 and the intermediate transfer belt 40 come into contact with each other. Further, on the outer peripheral surface side of the intermediate transfer belt 40, a secondary transfer roller 44 as a secondary transfer means is arranged at a position facing the drive roller 41. The secondary transfer roller 44 is pressed (urged) toward the drive roller 41 via the intermediate transfer belt 40 to form a secondary transfer portion N2 in which the intermediate transfer belt 40 and the secondary transfer roller 44 come into contact with each other.

The toner image formed on the photoconductor 11 is primarily transferred onto the intermediate transfer belt 40 by the action of the primary transfer roller 15 in the primary transfer unit N1. During the primary transfer step, a primary transfer bias (primary transfer voltage) having a polarity opposite to the normal charging polarity of the toner (positive electrode property in this embodiment) is applied to the primary transfer roller 15. For example, when forming a full-color image, images of each color of yellow, magenta, cyan, and black formed on each photoconductor 11 are sequentially transferred so as to be superimposed on the intermediate transfer belt 40. The toner (primary transfer residual toner) remaining on the surface of the photoconductor 11 after the primary transfer step is recovered by the developing apparatus 14.

The toner image formed on the intermediate transfer belt 40 is sandwiched and conveyed between the intermediate transfer belt 40 and the secondary transfer roller 44 by the action of the secondary transfer roller 44 in the secondary transfer unit N2. Is secondarily transferred to. During the secondary transfer step, a secondary transfer bias (secondary transfer voltage) having a polarity opposite to the normal charging polarity of the toner (positive electrode property in this embodiment) is applied to the secondary transfer roller 44. The transfer material P is sent out from the cassette 31 by the feed roller 32 and is conveyed to the secondary transfer unit N2 by the transfer roller pair 1 as in the first embodiment. Further, the transfer material P transferred to the secondary transfer unit N2 by the transfer roller pair 1 is statically eliminated by the static elimination device 2. Further, the transfer material P to which the toner image is transferred is subjected to the fixing treatment in the same manner as in Example 1, and then discharged to the discharge tray 19.

The toner remaining on the surface of the intermediate transfer belt 40 after the secondary transfer step (secondary transfer residual toner) is removed from the surface of the intermediate transfer belt 40 by the belt cleaning device 45 as an intermediate transfer body cleaning means and recovered. The belt cleaning device 45 scrapes the secondary transfer residual toner from the surface of the moving intermediate transfer belt 40 by the cleaning blade 45a arranged in contact with the intermediate transfer belt 40, and stores the secondary transfer residual toner in the collection container 45b. The cleaning blade 45a is an example of a cleaning member that contacts the intermediate transfer belt 40 downstream of the secondary transfer unit N2 and upstream of the primary transfer unit N1 in the moving direction of the intermediate transfer belt 40 to remove toner from the intermediate transfer belt 40. Is.

In such an image forming apparatus 100, the paper dust adhering to the image forming surface of the transfer material P is transferred to the intermediate transfer belt 40 by the secondary transfer portion N2, and the paper dust collects the secondary transfer residual toner. May adhere to the cleaning blade 45a. In this case, paper dust is caught between the cleaning blade 45a and the intermediate transfer belt 40, and a gap is formed between the cleaning blade 45a and the intermediate transfer belt 20, resulting in poor cleaning of the intermediate transfer belt 40. Sometimes. Further, the paper dust that has passed through the cleaning blade 45a through the gap may adhere to the photoconductor 11 and cause an image defect.

2. 2. Paper dust removing device Next, the paper dust removing device 10 in this embodiment will be described. FIG. 4 is a schematic cross-sectional view of the vicinity of the paper dust removing device 10 in this embodiment.

The paper dust removing device 10 in this embodiment has the same configuration as the paper dust removing device 10 in the first embodiment. That is, the paper dust removing device 10 is composed of a transport roller pair 1, a static elimination device 2, a sheet 3, a tray 4, power supplies 5, 6, and the like, as in the first embodiment. A negative voltage is applied from the first power source 5 to the transfer roller 1a that comes into contact with the image forming surface of the transfer material P in the transfer roller pair 1. Further, a positive voltage is applied to the static eliminator needle 2b of the static eliminator 2 from the second power source 6.

Also in the image forming apparatus 100 adopting the intermediate transfer method, it is possible to remove the positively charged paper dust from the image forming surface of the transfer material P by the same paper dust removing mechanism 10 as in the first embodiment. As a result, image defects due to paper dust adhering to the intermediate transfer belt 40 can be suppressed. Further, by suppressing the adhesion of the paper dust to the intermediate transfer belt 40, it is suppressed that the paper dust reaches the cleaning blade 45a, and the paper dust adheres to the cleaning blade 45a to clean the intermediate transfer belt 40. Defects can be suppressed. Further, according to the present embodiment, it is possible to prevent the paper dust that has passed through the cleaning blade 45a from reaching the photoconductor 11, and it is possible to suppress image defects due to the paper dust adhering to the photoconductor 11. Further, by removing the charge of the transfer material P charged by the transfer roller 1a by the static elimination device 2, it is possible to suppress image defects in the secondary transfer unit N2 due to the transfer material P being charged. The image defect in the secondary transfer unit N2 is that the toner image on the intermediate transfer belt 40 or the transfer material P is disturbed by the electric discharge between the intermediate transfer belt 40 and the transfer material P.

[Other]
Although the present invention has been described above with reference to specific examples, the present invention is not limited to the above-mentioned examples.

In the above-described embodiment, the image forming apparatus employs a photoconductor cleanerless configuration. However, the present invention can also be applied to a configuration provided with a photoconductor cleaning device for removing transfer residual toner from the photoconductor. 5 and 6 show an example in which the present invention is applied to an image forming apparatus provided with a photoconductor cleaning apparatus. FIG. 5 shows a case where the ETB method is adopted like the image forming apparatus 100 of FIG. 1, and FIG. 6 shows a case where the ITB method is adopted like the image forming apparatus 100 of FIG. In the image forming apparatus of FIGS. 5 and 6, elements having the same or corresponding functions or configurations as those of the image forming apparatus 100 of FIGS. 1 and 3 are designated by the same reference numerals. In the image forming apparatus 100 of FIGS. 5 and 6, the transfer residual toner remaining on the photoconductor 11 after the toner image is transferred from the photoconductor 11 to the transfer target (transfer material P or intermediate transfer body 40) is cleaned by the photoconductor. It is removed from the photoconductor 11 by the device 16 and recovered. The photoconductor cleaning device 16 scrapes and collects the transfer residual toner from the surface of the moving photoconductor 11 by a cleaning blade arranged in contact with the photoconductor 11. Further, the image forming apparatus 100 of FIGS. 5 and 6 has a charging roller 120 as a charging means for charging the photoconductor 11. In the image forming apparatus 100 of FIGS. 5 and 6, when the paper dust adheres to the photoconductor 11, the paper dust adheres to the cleaning blade of the photoconductor cleaning device 16 and is caught between the cleaning blade and the photoconductor 11. Sometimes. Then, a gap may be formed between the cleaning blade and the photoconductor 11 to cause a cleaning defect, or a paper dust that has passed through the cleaning blade through the gap may cause an image defect. Therefore, even in an image forming apparatus having such a configuration, it is effective to prevent the paper dust from adhering to the photoconductor 11 by the paper dust removing mechanism 10.

In addition, paper dust is removed from the image forming surface of the transfer material by the potential difference due to the voltage applied to the transfer roller instead of the potential difference due to triboelectric charging between the transfer roller and the transfer material, and the transfer material charged at that time is removed by static elimination means. The above-mentioned effect can be obtained if the configuration is such that static electricity is eliminated. Therefore, as described above, either positive electrode or negative electrode voltage may be applied to the transport roller depending on the charging polarity of the paper dust reaching the transport roller, and a plurality of voltages having different polarities are applied to the transport roller. A transport roller may be provided. Further, the polarity of the voltage applied to the transport roller may be switched between positive electrode and negative electrode depending on the type of transfer material used for image formation and the like.

Further, when applying a voltage to the static elimination means, it is desirable to apply a voltage having a polarity opposite to the voltage applied to the transport rollers arranged adjacent to the upstream side of the static elimination means at least in the transfer direction of the transfer material. AC voltage may be applied. Further, a plurality of static elimination means to which voltages having different polarities are applied may be provided.

Further, in the above-described embodiment, the image carrier was a photoconductor (first image carrier) or an intermediate transfer member (second image carrier), but the image carrier is an electrostatic recording dielectric. The present invention can also be applied to an image forming apparatus.

1 Conveying roller vs. 2 Static elimination device 1a Conveying roller 1b Opposing roller 2a Holder 2b Static elimination needle 10 Paper dust removal mechanism 11 Photoreceptor 20 Transfer belt 40 Intermediate transfer belt

Claims (6)

An image forming portion that forms a toner image on an image carrier charged with a predetermined polarity,
A transfer means for transferring a toner image from the image carrier to a transfer material at a transfer unit by applying a voltage having a polarity opposite to that of the predetermined polarity.
A first power supply that outputs a voltage having a polarity opposite to that of the predetermined polarity,
Wherein in the conveying direction of the transfer material is conveyed to the transfer section provided upstream of the transfer portion, the toner image of the transfer material is brought into contact with the surface to be transferred is conveyed to the transfer material, and the second A transport roller that removes foreign matter from the transfer material by applying a voltage of the opposite polarity from the power supply of 1.
An opposing roller that is in contact with a surface opposite to the surface on which the toner image of the transfer material is transferred, conveys the transfer material together with the transfer roller, and is electrically grounded.
A second power supply that outputs a voltage of the predetermined polarity, and
A voltage of the predetermined polarity is applied by the second power source so as to face the surface on which the toner image of the transfer material is transferred, which is provided upstream of the transfer unit and downstream of the transfer roller in the transfer direction. in anda discharging means for the toner image of the transfer material to remove electrostatic load surface to be transferred,
Only the transfer roller is provided as a member that removes foreign matter from the transfer material that is transferred to the transfer unit by applying a voltage.
The static elimination means includes a static elimination needle to which a voltage is applied from the second power source, and removes electric charges on the surface on which the toner image of the transfer material is transferred without contacting the transfer material. Image forming device. An image forming portion that forms a toner image on an image carrier charged with a predetermined polarity,
A transfer means for transferring a toner image from the image carrier to a transfer material in a transfer portion by applying a voltage having a polarity opposite to that of the predetermined polarity.
A power supply that outputs a voltage having a polarity opposite to that of the predetermined polarity,
The transfer material is provided upstream of the transfer unit in the transfer direction of the transfer material to be conveyed to the transfer unit, and the transfer material is conveyed in contact with the surface on which the toner image of the transfer material is transferred, and the power supply A transport roller that removes foreign matter from the transfer material by applying a voltage of the opposite polarity.
An opposing roller that is in contact with a surface opposite to the surface on which the toner image of the transfer material is transferred, conveys the transfer material together with the transfer roller, and is electrically grounded.
It is provided upstream of the transfer unit and downstream of the transfer roller in the transfer direction, faces the surface on which the toner image of the transfer material is transferred, and removes charges on the surface on which the toner image of the transfer material is transferred. With static elimination means,
Only the transfer roller is provided as a member that removes foreign matter from the transfer material that is transferred to the transfer unit by applying a voltage.
The static elimination means includes an electrically grounded static elimination needle, and the static elimination needle removes electric charges on the surface on which the toner image of the transfer material is transferred without contacting the transfer material. Forming device. The image forming apparatus according to claim 1 or 2 , wherein the image carrier is a photoconductor. The image forming unit includes an electrostatic image forming means for forming an electrostatic image on the image carrier, and a developing device for supplying toner to the electrostatic image formed on the image carrier. toner remaining on the image bearing member from the carrier after the toner image is transferred to the transfer material, the image forming apparatus according to claim 3, characterized in that it is recovered to the developing device. The image forming apparatus according to claim 3 or 4 , wherein each has a plurality of the image forming portions including the image carrier. The image forming apparatus according to any one of claims 1 to 5 , wherein the transfer roller also functions as a resist roller used for adjusting the transfer timing or the transfer posture of the transfer material.

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