JP5169514B2 - Image forming apparatus - Google Patents

Description

  The present invention relates to an image forming apparatus such as a copying machine, a printer, a facsimile machine, or a multi-function machine that combines two or more of them.

  In an image forming apparatus that employs an electrophotographic system such as a copying machine, a printer, a facsimile machine, or a combination machine combining two or more of these, a toner image is usually formed on an image carrier such as a photoconductor. A latent image is formed, and the electrostatic latent image is developed to form a visible toner image. The visible toner image is transferred to a recording medium such as recording paper, or is temporarily transferred to an intermediate transfer member such as an intermediate transfer belt. The toner image is transferred and secondarily transferred from the intermediate transfer member to a recording medium such as recording paper, and the toner image thus transferred to the recording medium is fixed to the recording medium.

  In such an image forming apparatus, a method of conveying recording paper from a recording paper stacking unit such as a paper feeding tray or a paper feeding cassette to an image forming unit (a transfer unit and a fixing unit) and a discharging unit includes rubber and metal. The most common one is a resin transport roller.

  However, since this method uses friction between the recording paper and the conveying roller, a large amount of paper dust is generated from the roller contact surface of the recording paper rubbed by the roller. In particular, the higher the speed of the high-speed machine, the greater the amount generated.

  On the other hand, in such an image forming apparatus, when the paper dust is conveyed to the transfer unit and adheres to an electrostatic latent image carrier represented by a photoreceptor, the quality of the formed image is improved. Or the electrostatic latent image carrier or the like is damaged. This is particularly problematic when acid paper is used as recording paper.

  In addition, paper dust attached to the transport roller accumulates as it is used, making the frictional force between the roller and the recording paper unstable, reducing paper feed accuracy due to variations in transport speed, and transport failure. Cause.

  In order to eliminate this cause, the conventional measures have been taken by periodic cleaning and replacement of the transport rollers. Has been. In particular, when acid paper is used as the recording paper, there is a possibility that image defects may occur because the paper feed roller portion has more paper dust than other portions. Also, because of the large amount of paper dust generated from the edge of the recording paper, after forming an image using recording paper of the same size continuously, the width of the recording paper (the width of the recording paper in the direction perpendicular to the transport direction) ) When an image is formed using a recording paper of a larger size, there is a possibility that a lot of paper dust is generated at the end portion of the continuously used recording paper and an image defect is generated.

  In any case, removing the paper dust by simply scraping the paper dust and holding the paper dust in the paper dust reservoir will not only scrape the paper dust because the paper dust will immediately overflow from the paper dust reservoir. Technology has been developed to transport scraped paper dust to the paper dust reservoir.

  Japanese Patent Laying-Open No. 2003-267578 (Patent Document 1) discloses an image forming apparatus capable of reliably transporting paper dust removed by a paper dust removing unit with a paper dust transporting unit. The image forming apparatus includes a paper dust removing unit for removing paper dust from a recording medium supplied to the image forming unit, and a paper dust disposed below the paper dust removing unit and falling from the paper dust removing unit. An image forming apparatus including a paper dust transport unit for transporting the paper, wherein a regulation wall is provided in the middle of the paper powder transport unit in the transport direction.

  According to this image forming apparatus, the paper dust of the recording medium supplied to the image forming means is removed from the paper dust removing means after being removed by the paper dust removing means, and then is conveyed in the transport direction by the paper dust conveying means. It is conveyed along. In the transport by the paper dust transport unit, when the paper dust exceeds a regulation wall provided in the middle of the transport direction, movement in the reverse direction of the transport direction is regulated by the regulation wall. Therefore, the paper dust is prevented from moving in the reverse direction of the conveyance direction from the regulation wall by the paper dust conveyance means, and it is possible to achieve removal of a sufficient amount of paper dust that is reliably conveyed.

JP 2003-267578 A

  However, in the image forming apparatus disclosed in Patent Document 1, paper dust removing means (corresponding to the paper dust removing roller in the embodiment of Patent Document 1) and paper powder conveying means (spiral shape in the embodiment of Patent Document 1). (Corresponding to the auger member formed in the above) is provided separately and spaced apart. For this reason, a large space is required for paper dust removal and paper dust conveyance. Therefore, when realizing high functionality such as full color required in an image forming apparatus, if a large space is required for paper dust removal and paper dust transport and recovery, the apparatus becomes large. Cannot be avoided.

  Accordingly, the present invention provides an image forming apparatus capable of forming a toner image on an electrostatic latent image carrier, and transferring and fixing the toner image on a recording paper, wherein the toner image is matched with the arrival timing of the toner image. An image forming apparatus equipped with a pair of registration rollers for feeding a recording sheet to a transfer position for transferring a toner image onto the recording sheet. Paper powder is removed and conveyed and collected, and in particular, the recording sheet is supplied to the pair of registration rollers. It is an object of the present invention to provide an image forming apparatus capable of removing and conveying and collecting paper dust generated at the time and reaching a registration roller pair together with a recording sheet by a mechanism that does not require a large space.

In order to solve the above problems, the present invention basically provides the following image forming apparatus.
An image forming apparatus capable of forming a toner image on an electrostatic latent image carrier and transferring and fixing the toner image on a recording paper, wherein the toner image is recorded on the recording paper in accordance with the arrival timing of the toner image. An image forming apparatus equipped with a pair of registration rollers for feeding recording paper to a transfer position to be transferred to
The registration roller surface of the registration roller pair that contacts the recording paper surface to which the toner image is transferred is a roller on which the first material is applied, and a spiral member formed from the second material is applied to the roller around the rotation shaft. The spiral roller that is worn is placed in contact with the spiral member,
The first material and the second material have a charge polarity of paper dust generated from the recording paper supplied to the pair of registration rollers by the frictional charging between the two members. It is a material that is charged with a reverse polarity charge,
The spiral member of the spiral roller is provided with a conductive member in a portion that conveys paper dust in a direction parallel to the rotation axis,
The image forming apparatus, wherein the potential of the conductive member is set to a ground potential or a potential having a polarity different from a charging polarity of paper dust.
More specifically, the present invention provides the following first and second image forming apparatuses.
(1) First image forming apparatus In the basic image forming apparatus described above, the rotating shaft of the spiral roller is a conductive rotating shaft, and the conductive member of the spiral member of the spiral roller is the conductive material. rises in a state of being electrically connected to the rotary shaft continuously from the electrically conductive rotating shaft, an image forming apparatus that is provided with helical member side portion made conductive.
(2) Second image forming apparatus In the basic image forming apparatus described above, the rotating shaft of the spiral roller is a conductive rotating shaft, and the conductive member of the spiral member of the spiral roller is the conductive rotating shaft. A bias power source that is electrically connected to a shaft and that applies a bias voltage having a polarity opposite to the charging polarity of the paper dust to the conductive rotating shaft and the conductive member;
The electric potentials of the conductive rotating shaft and the conductive member are set to the ground potential when the recording paper is present on the registration roller pair, and the paper powder is charged by the bias power source when the recording paper is not present on the registration roller pair. Is an image forming apparatus set to a reverse polarity potential.

  The image forming apparatus according to the present invention may be a monochrome image forming apparatus or a color image forming apparatus (typically a full color image forming apparatus) capable of forming an image using two or more colors of toner.

An image forming apparatus that includes the image forming apparatus of the present invention and forms an image on a recording sheet is a resist for feeding the recording sheet to a transfer position for transferring the toner image to the recording sheet in accordance with the arrival timing of the toner image. Usually, a roller pair is mounted. In the image forming apparatus of the present invention, the surface of the registration roller in contact with the recording paper surface to which the toner image is transferred is a roller on which the first material is applied. A spiral roller is brought into contact with the roller to which the first material is applied. The spiral roller is a roller in which a spiral member formed of a second material is attached to a rotation shaft, and is applied to the second material by frictional charging between the first material and the second material. Is charged with the opposite polarity to the charged polarity of the paper dust (the paper dust is charged to either positive or negative). The spiral member of the spiral roller is provided with a conductive member at a portion where paper dust is conveyed in a direction parallel to the rotation axis. The potential of the conductive member is set to a polarity different from the ground potential or the charging polarity of the paper powder.

According to such a configuration, the paper dust of the recording paper often adheres to the roller to which the first material is applied. However, the second material of the spiral roller contacting the roller is charged with the charging polarity of the paper dust. Since the paper is attracted to the second material portion of the spiral roller because it is frictionally charged to the reverse polarity, the roller (which covers the first material covered with the recording paper surface to which the toner image is transferred) of the registration roller pair. Paper dust can be removed from the roller. Further, the spiral member of the spiral roller is provided with a conductive member at a portion where paper dust is conveyed in a direction parallel to the rotation axis, and the potential of the conductive member is equal to the ground potential or the paper dust. The charging polarity is different from the charging polarity. Here, the paper dust is assumed to be charged with a positive charge, the potential of the conductive member is a negative potential Ru different polarities der the charge polarity of the ground potential or paper dust. When the potential of the conductive member is the ground potential, the paper dust can be conveyed and collected by rotating the spiral roller and the spiral shape without adsorbing the paper dust. Moreover, when the electric potential of the conductive member is a negative electric potential, the paper dust attached to the roller to which the first material is applied can be electrically adsorbed. Even when the potential of the conductive member is a negative potential, paper powder can be transported and collected by rotating the spiral roller and the spiral shape if it is temporarily switched to the ground potential. .

  As described above, the image processing apparatus according to the present invention has both a paper dust removing function by frictional charging and a paper powder conveying function for conveying paper powder without adsorbing by providing conductivity to the conventional registration roller pair 1. Since only the spiral roller of the book is provided so as to abut, the apparatus does not increase in size, and paper dust that causes image defects can be removed and conveyed to be collected.

In the first image forming apparatus according to the present invention, the conductive rotary shaft is grounded, the potential of the conductive member may be a ground potential. When the potential of the conductive member is the ground potential, the paper dust can be conveyed and collected by rotating the spiral roller and the spiral shape without adsorbing the paper dust.

In the first image forming apparatus according to the present invention, a bias power source is connected to the conductive rotating shaft, and the potential of the conductive member charged by the bias power source is opposite to the charging polarity of the paper dust. It can also be a polar potential. When the potential of the conductive member is a negative potential, the paper dust adhering to the roller to which the first material is applied or the paper dust adsorbed to the frictionally charged portion of the spiral roller is electrically adsorbed. Can do.

Also in the first image forming apparatus, the potential of the conductive member is set to the ground potential when the recording paper exists in the registration roller pair, and the charged polarity of the paper dust when the recording paper does not exist in the registration roller pair. Can also be set to a reverse polarity potential. When there is no recording paper on the registration roller pair, the potential of the conductive member is negative and is adsorbed by the paper powder adhering to the roller coated with the first material or the frictionally charged portion of the spiral roller. The paper dust can be adsorbed electrically. When recording paper is present on the pair of registration rollers, the potential of the conductive member is temporarily switched to the ground potential, so that the paper dust can be conveyed and collected by the rotational operation and spiral shape of the spiral roller. Further, when the recording paper is present on the pair of registration rollers, since the bias voltage is not applied to the conductive member, it is in a ground potential state, so that the influence of the bias voltage on the transfer portion via the recording paper can be prevented.

The following can be said in both the first and second image forming apparatuses.
The first material may be polyvinyl chloride, and the second material may be polyurethane. By such a combination of materials, the second material can be appropriately frictionally charged.

  You may further provide the press-contact member which press-contacts at least the part which carries out friction charging in the spiral roller, without inhibiting rotation of the spiral roller. This pressure contact member can remove the paper dust adsorbed to at least the frictionally charged portion of the spiral roller.

  The pressure contact member may be a comb-like member made of polyethylene terephthalate. This comb-like member can remove paper dust adsorbed on at least the frictionally charged portion of the spiral roller.

  A storage unit that stores paper powder conveyed in a direction parallel to the rotation axis by the spiral member of the spiral roller; and a charge removal unit that removes the electric charge of the paper powder before being stored in the storage unit. Also good. Uncharged paper dust can be retained in the reservoir.

  As described above, according to the present invention, an image forming apparatus capable of forming a toner image on an electrostatic latent image carrier and transferring and fixing the toner image on a recording paper. This is an image forming apparatus equipped with a pair of registration rollers for feeding the recording paper to a transfer position for transferring the toner image onto the recording paper in accordance with the timing. It is possible to provide an image forming apparatus that can remove and convey and collect paper dust that is generated when paper is supplied and reaches the registration roller pair together with the recording paper by a mechanism that does not require a large space.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same parts are denoted by the same reference numerals. Their names and functions are also the same. Therefore, detailed description thereof will not be repeated.

<First Embodiment>
The image forming apparatus according to the first embodiment of the present invention will be described below.
[Entire configuration of image forming apparatus]
FIG. 1 shows an example A of an image forming apparatus according to this embodiment.

  An image forming apparatus A whose cross section is shown in FIG. 1 is a monochrome image forming apparatus (monochrome printer). The image forming apparatus A according to the present invention may be such a monochrome image forming apparatus or a color image forming apparatus (typically a full color image forming apparatus) capable of forming an image using two or more colors of toner.

  The image forming apparatus A is equipped with two paper supply units 6 each having a paper feed tray 61, and a registration roller unit 600 for aligning the leading edge position of the fed paper and the image writing position. In the image forming apparatus A, the photosensitive member 1 is charged by the charging unit 2, and an electrostatic latent image is captured on the photosensitive member 1 by the image exposure unit 3 including a semiconductor laser, various lenses, a polygon mirror, and the like. The electrostatic latent image is developed into a toner image by the unit 4, the toner image is transferred to the recording medium S (hereinafter sometimes referred to as recording paper S) by the transfer unit 5, and then the toner is applied to the recording medium S by the fixing unit 7. The image is fixed and discharged by the discharge unit 8.

  The image forming apparatus A includes a drum-type negatively chargeable photoreceptor 1 that is driven to rotate, and a corona discharge charging unit to which a charging voltage is applied to the surface of the photoreceptor 1 from a charging power supply device (not shown). 2 is uniformly charged to a predetermined potential, and an image exposure unit 3 performs image exposure on the charged region to form an electrostatic latent image, and the latent image is negatively charged using the developing roller 41 of the developing unit 4. A visible toner image can be formed by reversal development with this toner.

  The visible toner image formed on the photosensitive member 1 is recorded on a transfer sheet (recording sheet) supplied from the sheet feeding tray 61 by a pickup roller 62 that moves up and down and a pair of sheet feeding rollers 63. Transferred to the medium S. The pair of paper feed rollers 63 has a double feed prevention function that feeds the recording papers stacked in the paper feed tray 61 one by one. This double feed prevention function includes, for example, a torque limiter reverse roller system. In this method, one roller of the paper feed roller pair 63 is driven, and a torque limiter is connected to the other roller for reverse rotation. By using the torque limiter slip and the reverse rotation of the roller, a stable and highly accurate double feed prevention function can be realized.

  The registration roller unit 600 sends the recording medium S to the transfer unit 5 in synchronization with the visible toner image. Details of the registration roller unit 600 will be described later. The recording medium S onto which the toner image has been transferred by the transfer unit 5 is heated and pressed by the fixing unit 7 so that the toner image is fixed on the recording medium S to be a monochrome image. The recording medium S on which the toner image is fixed in this manner is discharged onto the discharge tray 82 by the discharge roller pair 81 of the discharge unit 8. The transfer residual toner on the photoreceptor 1 is removed and cleaned by a cleaning blade.

  The image forming apparatus A can be a so-called four-cycle full-color image forming apparatus by using a developing unit as described below. A yellow developing unit, a magenta developing unit, a cyan developing unit, and a black developing unit are mounted on a rack that is driven to rotate the developing unit. These four-color developing units are configured in, for example, cartridges that are detachable from a rack. An electrostatic latent image corresponding to each color is sequentially formed on the photoconductor 1 based on image data of each color of yellow, magenta, cyan, and black, and the latent image corresponding to one color is formed each time the latent image is formed. The image is developed by a developing unit corresponding to the color among the four color developing units. The toner images of the respective colors sequentially formed on the photosensitive member 1 in this way are primarily transferred to an intermediate transfer belt (an example of an intermediate transfer member) every time one toner image is formed, and first. The toner image is transferred onto the transferred toner image. The multiple toner images formed on the intermediate transfer belt in this way are supplied one by one from the paper feed tray 61 by the paper feed roller pair 63, and sent in synchronization with the multiple toner images by the registration roller unit 600. The image is secondarily transferred to the recording medium S such as transfer paper, and is fixed to the recording medium by heating and pressurization at the fixing unit 7 to form a full color image. In such a full-color image forming apparatus A, a monochrome image can be formed by using any one of the four developing units, or any two or three developing units of the four developing units. A color image can also be formed using.

  In addition, even a tandem type full-color image forming apparatus can be applied as the image forming apparatus according to the present embodiment. That is, an image forming apparatus using recording paper as a recording medium, and an image on which a registration roller unit for feeding the recording paper to a transfer position for transferring the toner image held by the electrostatic latent image carrier onto the recording paper is mounted. Any forming apparatus may be used.

[Occurrence of paper dust and deterioration of photoconductor]
The relationship between the generation of paper dust and the deterioration of the photoreceptor 1 in such an image forming apparatus will be described. Based on this relationship, a position for collecting the removed paper dust is determined.

  FIG. 2 is a diagram showing the relationship between the width and position of the pair of paper feed rollers 63 (only one paper feed roller is shown in FIG. 2) and the characteristic deterioration position 10 of the photoreceptor 1. In the paper supply unit 6, the recording paper is conveyed to the transfer unit 5 one by one using the friction between the recording paper S and the paper feed roller pair 63. For example, the width of the paper feed roller pair 63 in the direction perpendicular to the recording paper conveyance direction is (substantially) smaller than the width of the photoreceptor 1. Further, a large amount of paper dust is generated from the roller contact surface of the recording paper S rubbed by the paper feed roller pair 63. When such paper dust reaches the photoconductor 1, it adheres to the photoconductor 1 and may deteriorate the characteristics of the photoconductor 1 and cause image defects. That is, the portion of the characteristic deterioration position 10 of the photoconductor 1 is a position where the paper dust easily reaches, and is a position where the characteristics of the photoconductor 1 deteriorate due to the reached paper dust.

  FIG. 3 is a diagram showing the relationship between the width of the recording sheet S (the width in the direction perpendicular to the conveyance direction of the recording sheet S), the maximum width of the recording sheet S, and the characteristic deterioration position of the photosensitive member. In the recording paper S, a lot of paper dust is generated from its end. For this reason, if an image is formed using a recording paper 14 having a size larger than the width of the recording paper 12 after an image is formed using the recording paper 12 of the same size continuously, the recording paper 12 used continuously is formed. Since a large amount of paper dust is generated in the end portion 13, there is a possibility that an image defect is generated at the characteristic deterioration position 11 of the photoconductor 1 corresponding thereto. That is, the portion of the photosensitive member 1 where the characteristic is deteriorated 11 is a position where the paper dust easily reaches the recording paper 14 when the width of the recording paper is increased, and the characteristics of the photosensitive member 1 deteriorate due to the paper dust that has reached. It is a position to do.

  In such an image forming apparatus, it is impossible to completely eliminate paper dust generated from the recording paper S. For this reason, in the image forming apparatus according to the present embodiment, the registration roller unit 600 generates paper dust (generated from the position corresponding to the paper feed roller pair 63 of the recording paper S or from the end of the recording paper having a small paper width). The paper dust adhering to the conveying roller) is removed by a length corresponding to the paper width (conveying roller width), and the paper dust removed from the conveying roller is conveyed to a position separated from the conveying roller and the recording paper and collected. To do. Thus, by moving the removed paper dust, paper dust does not accumulate in the width portion of the paper feed roller pair 63 or the end position of the small recording paper, and the photosensitive member 1 is partially collected. Deterioration can be avoided and the occurrence of image defects can be reduced.

[Registration roller structure]
The registration roller unit 600 of the image forming apparatus according to the present embodiment will be described in detail. 4 is a top view of the registration roller unit 600, FIG. 5 is a front view of the registration roller unit 600, and FIG. 6 is a side view of the registration roller unit 600. With reference to these drawings, the structure of the registration roller unit 600 will be described.

  The registration roller unit 600 includes a urethane rubber roller 610 and a tube roller 620 around which a polyvinyl chloride tube is wound. The recording paper S is sandwiched between the urethane rubber roller 610 and the tube roller 620 as a pair of registration rollers, and the recording paper S is conveyed to the transfer unit 5 at a predetermined timing. The urethane rubber roller 610 is rotationally driven in the direction shown in FIG. 6 by a drive unit 612 configured by a motor. A gear 611 is provided on the opposite side of the drive portion 612 of the urethane rubber roller 610, and this gear 611 meshes with the gear 621 of the tube roller 620, and the tube roller 620 is driven to rotate by the gear 621. Since the peripheral speed of the urethane rubber roller 610 and the peripheral speed of the tube roller 620 need to be the same, the gear 611 and the gear 621 are the same.

  The registration roller unit 600 according to the present embodiment is characterized by including a spiral roller 630 that contacts the tube roller 620. The spiral roller 630 is a roller in which polyurethane foam is wound around a metal shaft in a spiral shape. The gear 621 of the tube roller 620 is engaged with the gear 631 of the spiral roller 630, and the spiral roller 630 is driven to rotate by the gear 631. Note that the peripheral speed of the tube roller 620 and the peripheral speed of the spiral roller 630 need to be different because they need to be frictionally charged as described later, and the gear 621 and the gear 631 are different. For example, the gear ratio between the gear 621 and the gear 631 is determined so that the spiral roller 630 rotates faster than the tube roller 620.

  Thus, on the opposite side of the drive portion 612 of the urethane rubber roller 610, there is a gear 621 that rotates the tube roller 620, and the spiral roller 630 is further rotated by the gear 631 of the spiral roller 630 via the gear 621 of the tube roller 620. It is driven and rotated at different peripheral speeds. For this reason, a new drive mechanism for the spiral roller 630 is not provided, and a simple configuration (a configuration in which the apparatus is not enlarged) can be realized.

  The end surface of the outermost diameter of the spiral tooth of the spiral roller 630 (the surface forming the outermost periphery) is rubbed at a peripheral speed different from that of the tube roller 620 to hit the tube roller 620. Thereby, the spiral roller 630 is frictionally charged. At this time, the charging polarity of the spiral roller 630 is opposite to the charging polarity of the paper powder. Due to the frictional charging of the spiral roller 630, paper dust attached to the tube roller 620 is collected by the spiral roller 630. As will be described in detail later, the spiral roller 630 is conductive on the metal shaft and the side surfaces of the spiral teeth, and the conductive portion is grounded, so the spiral roller 630 does not adsorb the charged paper dust. The paper dust is moved to the gear 631 side (the right side in FIG. 5) by the rotation operation and the spiral shape.

  The spiral roller 630 is covered with an upper cover 642 and a lower cover 640 provided with a paper dust collecting unit 641. The material of these covers (which can be said to be the case for housing the spiral roller 630) is preferably one that does not have a function of being charged and adsorbing paper dust. It is also preferable that these covers are formed of a conductive material and grounded.

  A paper dust collection unit 641 is formed as a part of the lower cover 640 at a position corresponding to the length of the spiral roller 630 of the registration roller unit 600. By rotating the spiral roller 630, the paper dust collected from the tube roller 620 is conveyed to the paper dust collecting unit 641 and stored as paper dust 900 in the paper dust collecting unit 641. As shown in FIGS. 5 and 6, the position of the paper dust collection unit 641 is provided at the end of the spiral roller 630 and is sufficiently separated from the tube roller 620. For this reason, it is possible to store paper powder that has a strong tendency to reach the characteristic deterioration position shown in FIG. 2 or FIG. 3 at a sufficiently separated position, and the recovered paper powder 900 is attached to the tube roller 620 again. Can be difficult. That is, the paper dust collecting unit 641 is provided on the outer side of the spiral roller 630 or on the outer side of the spiral roller 630 and on the outer side of the maximum width of the recording paper S.

[Internal structure of registration roller]
Further, the internal structure of the registration roller unit 600 will be described in detail. FIG. 7 is a front view of the registration roller unit 600 where the upper cover 642 is removed and the PET sheet 650 can be seen. FIG. 8 is a front view of the registration roller unit 600 and the upper cover 642, the lower cover 640, and the PET sheet. FIG. 9 is a side view of the registration roller unit 600 and a cross-sectional view of the paper dust collecting unit 641. The internal structure of the registration roller unit 600 will be described with reference to these drawings.

  As shown in FIG. 7, the end surfaces of the spiral teeth of the spiral roller 630 of the registration roller portion 600 (the surface that spirally forms the outer diameter and the distance from the central axis changes periodically, Provided so that the tip of the PET sheet 650 faces the center of the rotation axis of the spiral roller 630 so that a thin sheet material (hereinafter referred to as PET sheet) 650 such as comb-shaped PET is always in contact with the groove portion) It has been. Like the PET sheet 650C, which is the most downwardly-oriented aspect of the three PET sheets 650 (PET sheet 650A, PET sheet 650B, and PET sheet 650C) in FIG. 9, the PET sheet 650 faces downward. The spiral roller 630 is always provided in pressure contact with the end face of the teeth. Therefore, when the end face of the spiral tooth of the spiral roller 630 is the largest, the PET sheet 650 is pushed up by the end face of the spiral tooth of the spiral roller 630 like the PET sheet 650A, and the spiral tooth of the spiral roller 630 is When the end face of the spiral roller 630 is the smallest (the rotational axis of the spiral roller 630), the PET sheet 650 is placed on the end face of the spiral tooth of the spiral roller 630 even when the height of the spiral tooth is lowered as in the PET sheet 650C. Touching. Since the PET sheet 650 is provided in this way, the PET sheet 650 comes into contact with the end face of the tooth of the spiral roller 630 and the spiral roller 630 rotates. Therefore, the step (the outermost diameter that is the peak portion) in the spiral roller 630 is rotated. The PET sheet 650 is swung by a step between the end surface and the shaft that is the groove. As the PET sheet 650 is swung, the paper dust adhering to the end surfaces and side surfaces of the spiral teeth of the spiral roller 630 is scraped off. Thereby, paper dust removal is promoted, paper dust is prevented from clogging between spiral teeth, and reattachment of paper dust to the tube roller 620 can be prevented. In addition, although it is thought that paper dust may be scraped off, it may be scraped off, but in the following, it is described as “scrap off” including both cases.

  Further, as shown in FIG. 8, at both ends of the spiral roller 630, paper dust is prevented from further moving to move the paper dust to the paper dust collecting unit 641, and the driving unit 612 of the urethane rubber roller 610. A ring portion 635 is provided in order to prevent paper dust from getting around.

  Further, as shown in FIG. 8, a polyurethane foam 660 for preventing paper dust leakage is provided between the spiral roller 630 and the tube roller 620. Further, a PET sheet 670 is provided in the vicinity of the polyurethane foam 660. The PET sheet 670 is provided so that the polyurethane foam 660 for preventing paper dust leakage and the spiral roller 630 made of the same material do not directly contact each other. Since the PET sheets 670 do not directly contact the polyurethane foams, the rotational resistance of the spiral roller 630 can be reduced.

  Further, at the end of the spiral roller 630 on the paper powder conveying side, a static eliminating unit 680 is provided for eliminating the charge of the charged paper powder. After the charge of the paper dust is neutralized by the static eliminator 680, the paper dust is dropped to the paper dust collector 641 and is stored as paper dust 900 in the paper dust collector 641. Note that the static eliminating unit 680 can be a grounded conductive member or the like.

  The spiral roller 630 will be described in detail with reference to FIG. As shown in FIG. 10, the spiral roller 630 is a roller in which a polyurethane foam is wound around a metal shaft 634 in a spiral shape. The end surface 637 of the spiral tooth 633 of the spiral roller 630 (the surface that forms the outer diameter in a spiral shape and the distance from the central axis changes periodically) is the end surface of the outermost diameter that is different from the tube roller 620. Rub to hit the tube roller 620 at different peripheral speeds. As a result, the teeth 633 of the spiral roller 630 are frictionally charged.

  As shown in the enlarged view of FIG. 10, the side surface 636 of the spiral tooth 633 of the spiral roller 630 is made conductive, and the conductive side surface 636 is grounded together with the metal shaft 634. The spiral roller 630 moves the paper dust to the gear 631 side (the right side of the paper in FIG. 5) by rotating operation and spiral shape without adsorbing the charged paper dust, as indicated by the white arrow.

  Note that the end surface 637 of the tooth 633 is non-conductive and frictionally charged (frictionally charged to a polarity opposite to that of paper dust), and the side surface 636 of the spiral tooth 633 and the metal shaft 634 adjacent to it are conductive and grounded. Yes. In order to make the frictional charging state and the grounding state coexist at such a position, as shown in the enlarged view of FIG. 10, a non-conductive outer edge portion 638 is provided on the outer periphery of the side surface 636 of the spiral tooth 633. Have That is, if the outer edge portion 638 is not present and all of the side surfaces 636 of the spiral teeth 633 are conductive and grounded, the tube roller 620 may contact the conductive side surface 636 with the member. It is assumed that the side surface 636 of the spiral tooth 633 cannot be frictionally charged. For this reason, this outer edge portion 638 is provided.

  For example, the conductive side surface 636 may be formed by winding a spiral polyurethane foam around the metal shaft 634 and masking the end surface 637 and the outer edge portion 638 of the teeth 633 to spray a conductive material (metal powder or the like). Can be formed. At this time, the metal shaft 634 and the side surface 636 of the spiral tooth 633 are electrically connected to each other by the sprayed conductive material in the portion of the side surface 636 closest to the metal shaft 634. Note that the present invention is not limited to such a method for forming the conductive side surface 636.

[Removal and removal of paper dust on registration roller]
The operation of the image forming apparatus having the above structure will be described. In the following, the paper dust removal and collection operation of the registration roller unit 600 will be mainly described.

  When the image forming apparatus is operated and the recording sheet S reaches the registration roller unit 600, the process waits until a predetermined timing. At this time, the recording paper S is sandwiched between the urethane rubber roller 610 and the tube roller 620 which are a pair of registration rollers. The recording paper S is conveyed to the transfer unit 5 by the urethane rubber roller 610 and the tube roller 620 at a predetermined timing. At this time, the urethane rubber roller 610 is rotationally driven by the driving unit 612, and the driving force that rotates the urethane rubber roller 610 is transmitted through the gear 611, the gear 621, and the gear 631, and the tube roller 620 and the spiral roller 630 are transmitted. Rotate.

  The urethane rubber roller 610 and the tube roller 620 rotate at the same peripheral speed, but the tube roller 620 and the spiral roller 630 rotate at different peripheral speeds (the spiral roller 630 is faster than the tube roller 620), Since the polyvinyl chloride tube of the tube roller 620 and the spiral polyurethane foam of the spiral roller 630 come into contact with each other, they are rubbed, and the end surface 637 of the teeth 633 of the spiral roller 630 is frictionally charged to a polarity opposite to that of the paper dust. The

  The paper dust adhering to the tube roller 620 is adsorbed to the end surface 637 of the tooth 633 of the spiral roller 630 frictionally charged to the opposite polarity to the paper dust, as shown as paper dust 910 in FIG.

  The end surface 637 of the tooth 633 of the spiral roller 630 is provided so that the PET sheet 650 always comes into contact therewith, and when the spiral roller 630 rotates, the step (the end surface of the outermost diameter that is a peak portion and the groove portion) in the spiral roller 630 is rotated. The paper sheet 910 attached to the end surface 637 of the spiral tooth of the spiral roller 630 is scraped off as shown as the paper powder 920 in FIG. It is. At this time, since the shape of the PET sheet 650 is comb-shaped, it also hits the side surface of the tooth of the spiral roller 630. Therefore, the side surface of the spiral tooth of the spiral roller 630 (the conductive side surface 636 and the outer edge portion 638). Scrape off paper dust adhering to the surface. Note that since the conductive side surface 636 is grounded, it is considered that there is a strong tendency that the paper dust does not adhere to the conductive side surface 636. However, even if it adheres, the paper dust is scraped off.

  In the spiral roller 630, the metal shaft 634 and the side surface 636 of the spiral tooth 633 are grounded, and the charged paper powder does not adsorb or is difficult to adsorb. For this reason, the paper dust 920 scraped off by the PET sheet 650 is converted into a gear by the rotational operation and spiral shape of the spiral roller 630, as shown by the white arrows in FIGS. Move to the 631 side.

  Since the paper powder 920 moved by the spiral roller 630 has the ring portion 635, the paper powder 920 is moved to the paper powder collecting unit 641, and the paper powder 920 is prevented from entering the driving unit 612 of the urethane rubber roller 610. The The paper dust 920 moved by the spiral roller 630 is discharged to the paper dust collecting unit 641 after the charge of the charged paper dust is eliminated by the static eliminating unit 680, and the paper dust 900 is transferred to the paper dust collecting unit 641. Is stored as.

  During the removal and collection of paper dust, a space (spiral) in which paper dust is formed by the upper cover 642 and the lower cover 640 by the polyurethane foam 660 provided between the spiral roller 630 and the tube roller 620. Leakage from a space (such as a case housing the roller 630) is prevented. Further, the PET sheet 670 provided in the vicinity of the polyurethane foam 660 prevents the polyurethane foams (the polyurethane foam 660 for preventing paper dust leakage and the spiral roller 630) from directly contacting each other, thereby reducing the rotational resistance of the spiral roller 630. Has been.

  As described above, according to the image forming apparatus of the present embodiment, the end surface of the spiral roller 630 facing the tube roller is frictionally charged to the opposite polarity to the paper powder to adsorb the paper powder, and the spiral roller 630 The paper powder 920 can be collected by rotating the spiral roller 630 and the spiral shape so that the conveyance surface and the rotation shaft are grounded so that the paper powder is not adsorbed or difficult to adsorb. By moving the paper dust, the paper dust does not concentrate and accumulate at the position corresponding to the width of the pair of paper feed rollers and the position corresponding to the edge of the recording paper. Since there is no partial deterioration, the occurrence of image defects can be reduced. In order to realize such an effect, the conventional registration roller pair is provided with a single spiral roller having both charging property and conductivity, and a paper dust collecting unit is provided. As a result, the apparatus does not increase in size.

<Second Embodiment>
The image forming apparatus according to the second embodiment of the present invention will be described below. Note that the image forming apparatus according to the present embodiment has the metal shaft 634 in addition to the point that the metal shaft 634 and the conductive side surface 636 in the image forming apparatus described in the first embodiment are grounded. The other configuration is the same except that a bias voltage is applied to the conductive side surface 636. For this reason, descriptions other than differences will not be repeated here.

[Registration roller structure]
The registration roller unit 700 of the image forming apparatus according to the present embodiment will be described in detail. 11 is a top view of the registration roller unit 700 of the image forming apparatus according to the present embodiment, FIG. 12 is a front view of the registration roller unit 700 (bias on), and FIG. 13 is a front view of the registration roller unit 700 (bias). Off).

  As shown in these drawings, the registration roller unit 700 includes a bias application unit 710 for applying a bias voltage (a bias voltage having a polarity opposite to the charging polarity of paper dust) to the metal shaft 634 and the conductive side surface 636. . The bias applying unit 710 can apply a bias voltage having a polarity opposite to the charging polarity of the paper powder to the metal shaft 634 and the conductive side surface 636. In this way, paper dust attached to the tube roller 620 can be electrically adsorbed to the spiral roller 630 side. Alternatively, the paper dust adsorbed on the end surface 637 of the tooth 633 of the spiral roller 630 can be electrically adsorbed to the end surface 637 side of the tooth 633 of the spiral roller 630.

  When there is a recording sheet S in the registration roller unit 700, in order to prevent the transfer unit 5 from being affected by the bias voltage, the bias roller is not applied to the spiral roller 630 and the metal shaft 634 of the spiral roller 630 and The potential of the conductive side surface 636 is set to the ground potential. Note that such ON / OFF of the bias voltage is realized by controlling the changeover switch 711 by an arithmetic device that controls the entire image forming apparatus A or an arithmetic device that controls the registration roller unit 700. The change-over switch 711 is a switch that connects the metal shaft 634 and the conductive side surface 636 of the spiral roller 630 to either the ground (ground) side or the bias power supply side. In the following description, it is assumed that the bias voltage is turned on / off by an arithmetic device that controls the registration roller unit 700. Further, when the changeover switch 711 is switched to the ground side, the power supply to the bias applying unit 710 can be stopped.

  The registration roller unit 700 is provided with a registration sensor (not shown) that detects that the recording paper S has reached the registration roller unit 700. The registration sensor outputs an ON signal to the arithmetic unit when the recording paper S reaches the registration roller unit 700.

[Structure of bias application control to the registration roller section]
The bias application control in the registration roller unit 700 will be described in detail.
FIG. 14 is a flowchart showing a program structure of bias application control executed by an arithmetic device that controls the registration roller unit 700 (hereinafter simply referred to as an arithmetic device). The bias application control will be described below with reference to this flowchart.

  In step (hereinafter, step is referred to as S) 1000, the arithmetic unit determines whether or not paper feeding has been started. At this time, the arithmetic device determines whether or not paper feeding is started based on a signal, a sensor signal, or the like received from the arithmetic device that controls another mechanism. If it is determined that sheet feeding has started (YES in S1000), the process proceeds to S1010. Otherwise (NO in S1000), this process ends.

  In S1010, the arithmetic device drives the registration rollers. More specifically, the arithmetic unit transmits an operation command signal to the drive unit 612 of the registration roller unit 700. Thereby, the urethane rubber roller 610 rotates, and the tube roller 620 and the spiral roller 630 are driven to rotate.

  In S1020, the arithmetic device determines whether or not the registration sensor is on. If recording sheet S has reached registration roller unit 700 and the registration sensor is on (YES in S1020), the process proceeds to S1040. If not (NO in S1020), the process proceeds to S1030.

  In S 1030, the arithmetic device controls changeover switch 711 to apply a bias voltage to spiral roller 630. If a bias voltage is applied to the spiral roller 630, that state is maintained. Thereafter, the process proceeds to S1050.

  In S1040, the arithmetic unit controls changeover switch 711 to stop the application of the bias voltage to spiral roller 630, and set spiral roller 630 to the ground potential. When no bias voltage is applied to the spiral roller 630, the ground state is maintained. Thereafter, the process proceeds to S1050.

  In S1050, the arithmetic device determines whether or not registration roller unit 700 is continuously driven. At this time, the arithmetic device determines whether or not the registration roller unit 700 is continuously driven based on a signal, a sensor signal, or the like received from an arithmetic device that controls another mechanism. If it is determined that registration roller unit 700 is continuously driven (YES in S1050), the process returns to S1020. If not (NO in S1050), the process proceeds to S1060.

  In S1060, the arithmetic unit stops applying the bias voltage to spiral roller 630.

[Removal and removal of paper dust on registration roller]
The operation of the image forming apparatus having the above structure will be described. In the following, the paper dust removal and collection operation of the registration roller unit 700 will be mainly described.

  When the image forming apparatus is activated and sheet feeding is started (YES in S1000), when the recording sheet S does not reach the registration roller unit 700, the spiral roller 630 has a polarity opposite to the charging polarity of the paper dust. Is applied (NO in S1020, S1030). On the other hand, when the recording sheet S has reached the registration roller unit 700, the application of the bias voltage to the spiral roller 630 is stopped and brought to the ground potential (YES in S1020, S1040).

  When the recording paper S does not reach the registration roller unit 700, the bias applying unit 710 charges the metal shaft 634 of the spiral roller 630 and the end surface 637 of the teeth 633 with a polarity opposite to that of the paper dust.

  Paper dust 940 of FIG. 12 is applied to the metal shaft 634 of the spiral roller 630 or the end surface 637 of the teeth 633 of the paper roller (paper dust 930 of FIG. 11) attached to the tube roller 620 and charged to the opposite polarity to the paper dust. Adsorbed as shown.

  A part of the paper powder adsorbed on the spiral roller 630 side by the applied bias voltage is such that the PET sheet 650 is swung, and the paper powder 940 attached to the metal shaft 634 of the spiral roller 630 becomes the paper powder 950 of FIG. As shown.

  When the registration roller 700 has the recording paper S, no bias voltage is applied (YES in S1020, S1040), and the spiral roller 630 has the metal shaft 634 and the side surface 636 of the spiral tooth 633 grounded. Thus, the charged paper powder is not adsorbed or is hardly adsorbed. For this reason, a part of the paper dust adsorbed to the spiral roller 630 side by the applied bias voltage is caused to move the paper dust 920 by the rotational operation and spiral shape of the spiral roller 630 as shown by the white arrow in FIG. Move to the gear 631 side.

  As described above, according to the image forming apparatus according to the present embodiment, when there is no recording paper in registration roller unit 700, the bias voltage is applied so that the end surface of spiral roller 630 facing the tube roller is paper. The paper powder is adsorbed by charging it with a polarity opposite to that of the powder. When there is recording paper on the registration roller unit 700, the application of the bias voltage is stopped to ground the conveyance surface and the rotation shaft of the spiral roller 630 so as not to adsorb the paper powder. Depending on the spiral shape, paper dust 920 can be collected. Further, since the bias voltage is applied only when the recording paper S does not reach the registration roller unit 700, the transfer unit 5 is not affected via the recording paper S affected by charging.

  In the above description, the application of the bias voltage is stopped. However, the influence of the application of the bias voltage to the transfer unit 5 is small, and when priority is given to the function of adsorbing paper dust from the tube roller 620, A bias voltage can be always applied.

<Third Embodiment>
The image forming apparatus according to the third embodiment of the present invention will be described below. The image forming apparatus according to the present embodiment is different in that the paper powder collected in one direction in the image forming apparatus described in the first embodiment is collected in both directions. Other configurations are the same. For this reason, descriptions other than differences will not be repeated here.

  FIG. 15 is a front view of the registration roller unit 800, with the upper cover 642, the lower cover 640, and the PET sheet 650 removed. With reference to FIG. 15, the internal structure of registration roller unit 800 will be described.

  As shown in FIG. 15, the spiral roller 830 of the registration roller unit 800 has the spiral direction reversed at the center. When the spiral roller 830 rotates, the paper dust moves from approximately the center of the spiral roller 830 toward both ends, as indicated by white arrows. That is, paper dust can be collected by the rotational operation of the spiral roller 830 and the spiral shape.

  Since paper dust is collected at both ends, the lower cover 840 is formed with two paper powder collection units 841 and paper powder collection unit 842. Furthermore, a charge eliminating unit 880 and a charge eliminating unit 882 are provided at both ends of the spiral roller 830 where the paper dust is conveyed. The charge of the paper dust is removed by the charge removing unit 880, and then the paper powder is dropped to the paper dust collecting unit 841 and stored in the paper dust collecting unit 841 as the paper powder 900. The charge of the paper dust is removed by the charge removing unit 882. Then, the paper dust is dropped into the paper dust collecting unit 842 and stored as paper dust 902 in the paper dust collecting unit 842.

  As described above, according to the image forming apparatus according to the present embodiment, the paper dust conveyance distance in registration roller unit 800 can be substantially halved, so that paper dust can be more reliably collected in the paper dust collecting unit. .

  The embodiment disclosed this time is merely an example, and the present invention is not limited to the embodiment described above. The scope of the present invention is indicated by each claim in the claims after taking into account the description of the detailed description of the invention, and all modifications within the meaning and scope equivalent to the wording described therein are intended. Including.

1 is a diagram illustrating an outline of a configuration of a monochrome printer which is an example of an image forming apparatus according to a first embodiment of the present invention. It is a figure which shows the relationship between the position of a paper feed roller pair, and the characteristic deterioration position of a photoconductor. FIG. 5 is a diagram illustrating a relationship between a recording paper width and a maximum recording paper width and a characteristic deterioration position of a photoconductor. FIG. 2 is a top view of a registration roller unit in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a front view of a registration roller unit in the image forming apparatus illustrated in FIG. 1. FIG. 2 is a side view of a registration roller unit in the image forming apparatus illustrated in FIG. 1. FIG. 6 is a diagram (No. 1) illustrating an internal structure of a registration roller unit illustrated in FIG. 5. FIG. 6 is a second diagram illustrating the internal structure of the registration roller unit illustrated in FIG. 5. It is a figure which shows the internal structure of the registration roller part shown in FIG. It is a perspective view of a spiral roller. FIG. 6 is a top view of a registration roller portion of an image forming apparatus according to a second embodiment of the present invention. FIG. 10 is a front view (bias on) of a registration roller portion of an image forming apparatus according to a second embodiment of the present invention. FIG. 6 is a front view (bias off) of a registration roller portion of an image forming apparatus according to a second embodiment of the present invention. 6 is a flowchart illustrating a control structure of bias application processing in an image forming apparatus according to a second embodiment of the present invention. It is a front view of the registration roller part of the image forming apparatus which concerns on the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Photoconductor 2 Charging part 3 Image exposure part 4 Developing part 5 Transfer part 6 Paper supply part 7 Fixing part 8 Ejection part 600, 700, 800 Registration roller part 610 Urethane rubber roller 620 Tube roller 630, 830 Spiral roller 633 Teeth 634 Metal shaft 635 Ring part 636 Side face 637 End face 638 Outer edge part 640 Lower cover 641, 841, 842 Paper dust collecting part 642 Upper cover 650 Comb-like PET sheet 660 Polyurethane foam 670 PET sheet 680, 880, 882 Static elimination part 710 Bias application part 711 Changeover switch

Claims (9)

An image forming apparatus capable of forming a toner image on an electrostatic latent image carrier and transferring and fixing the toner image on a recording paper, wherein the toner image is recorded on the recording paper in accordance with the arrival timing of the toner image. An image forming apparatus equipped with a pair of registration rollers for feeding recording paper to a transfer position to be transferred to
The registration roller surface of the registration roller pair that contacts the recording paper surface to which the toner image is transferred is a roller on which the first material is applied, and a spiral member formed from the second material is applied to the roller around the rotation shaft. The spiral roller that is worn is placed in contact with the spiral member,
The first material and the second material have a charge polarity of paper dust generated from the recording paper supplied to the pair of registration rollers by the frictional charging between the two members. It is a material that is charged with a reverse polarity charge,
The rotating shaft of the spiral roller is a conductive rotating shaft,
The spiral member of the spiral roller is provided with a conductive member in a portion for conveying paper dust in a direction parallel to the rotation shaft, and the conductive member is electrically connected to the conductive rotation shaft. state rises continuously from the electrically conductive rotating axis, which is provided with helical member side portion made conductive,
The image forming apparatus according to claim 1, wherein the potential of the conductive member is set to a ground potential or a potential having a polarity different from a charging polarity of the paper powder. Before Kishirube conductive rotary shaft is grounded,
The image forming apparatus according to claim 1, wherein a potential of the conductive member is a ground potential. Bias power source is connected to the front Kishirube conductive rotary shaft,
The image forming apparatus according to claim 1, wherein a potential of the conductive member charged by the bias power source is a polarity opposite to a charging polarity of the paper powder. Before is provided with a bias power source for applying a bias voltage opposite in polarity to the charging polarity of the Kishirube conductive rotary shaft and the paper powder to the conductive member,
The potential of the conductive member is set to the ground potential when recording paper is present on the registration roller pair, and is set to a polarity opposite to the charged polarity of the paper powder by the bias power source when recording paper is not present on the registration roller pair. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. An image forming apparatus capable of forming a toner image on an electrostatic latent image carrier and transferring and fixing the toner image on a recording paper, wherein the toner image is recorded on the recording paper in accordance with the arrival timing of the toner image. An image forming apparatus equipped with a pair of registration rollers for feeding recording paper to a transfer position to be transferred to
The registration roller surface of the registration roller pair that contacts the recording paper surface to which the toner image is transferred is a roller on which the first material is applied, and a spiral member formed of the second material is provided on the roller as a conductive rotating shaft. The spiral roller attached to the contact member is arranged in contact with the spiral member;
The first material and the second material have a charge polarity of paper dust generated from the recording paper supplied to the pair of registration rollers by the frictional charging between the two members. It is a material that is charged with a reverse polarity charge,
The spiral member of the spiral roller is provided with a conductive member in a portion for conveying paper dust in a direction parallel to the conductive rotation shaft, and the conductive member is electrically connected to the conductive rotation shaft. And
A bias power source is provided for applying a bias voltage having a polarity opposite to the charging polarity of the paper dust to the conductive rotating shaft and the conductive member,
The electric potentials of the conductive rotating shaft and the conductive member are set to the ground potential when the recording paper is present on the registration roller pair, and the paper powder is charged by the bias power source when the recording paper is not present on the registration roller pair. An image forming apparatus having a reverse polarity potential . The image forming apparatus according to claim 1, wherein the first material is polyvinyl chloride, and the second material is polyurethane . The image forming apparatus according to claim 1, further comprising a pressing member that presses at least a portion that is frictionally charged in the spiral roller without hindering the rotation of the spiral roller . The image forming apparatus according to claim 7 , wherein the pressure contact member is a comb-like member made of polyethylene terephthalate . A storage section for storing paper powder conveyed in a direction parallel to the rotation axis by a spiral member of the spiral roller;
The image forming apparatus according to claim 1, further comprising a static elimination unit that removes the electric charge of the paper powder before being stored in the storage unit.

Images