JP2005055695A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming method and an image forming apparatus, for outputting a high-quality image, in which preferable measures are taken against image dust at a transfer part. <P>SOLUTION: In the image forming method having a latent image formation step for forming an electrostatic latent image on an image carrier 40, a development step for performing development by supplying toner to the electrostatic latent image, a primary transfer step for transferring the toner image formed on the image carrier 40 to an intermediate transfer body 10, and a secondary transfer step for transferring the toner image on the intermediate transfer body 10 to a sheet of paper, a step for providing an ion wind having the same polarity as received by the image surface of the sheet of paper after passing through the secondary transfer step is provided for the side of the image surface of the sheet of paper immediately after passing through the secondary transfer step. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to an image forming apparatus that forms an image by an electrophotographic process such as a copying machine or a printer, and more particularly, to an image forming apparatus that includes an intermediate transfer body that transfers and holds a toner image formed on an image carrier. .

2. Description of the Related Art Today, there are an increasing number of color image forming apparatuses such as color copiers and color printers in response to market demands.
A color image forming apparatus is provided with a developing device of a plurality of colors around one photoconductor, and a toner is adhered by these developing devices to form a composite toner image on the photoconductor, and the toner image is transferred. A so-called revolver type that records color images on paper and a plurality of photoconductors arranged side by side are each equipped with a developing device, and a single color toner image is formed on each photoconductor, and the single color toner images are sequentially formed. There is a so-called tandem type that transfers and records a composite color image on a sheet.
Comparing the revolver type and the tandem type, the former has only one photoconductor, so that there is an advantage that the size can be reduced relatively and the cost can be reduced. Times) Since full-color images are formed by repeating image formation, there is a drawback that speeding up image formation is limited, while the latter has the disadvantage of increasing the size and cost, but speeding up image formation There is an advantage that can be realized. In particular, the tandem type has been attracting attention recently because full-color and monochrome speeds are desired.

  The tandem type image forming apparatus includes a direct transfer system that sequentially transfers toner images on each photoconductor onto a sheet conveyed by a paper conveyance belt by a transfer device, and a primary transfer apparatus that transfers the toner images on each photoconductor. There is an indirect transfer type in which the toner image on the intermediate transfer body is transferred onto a sheet by a secondary transfer apparatus after being sequentially transferred to the intermediate transfer body once. Among these, the indirect transfer type equipped with an intermediate transfer member has been attracting attention because it has a high degree of freedom in layout in the apparatus and is advantageous for downsizing.

FIG. 14 is a diagram illustrating a configuration of a tandem type image forming apparatus including an intermediate transfer member. Each color toner image formed on the photoreceptor 40 by the four image forming units 18 corresponding to the four colors of black (Bk), yellow (Y), magenta (M), and cyan (C) is transferred to the primary transfer unit 62. The color image on the intermediate transfer belt 10 thus transferred is superimposed on the intermediate transfer belt 10 by the secondary transfer means 231, and the opposing transfer roller 231 is brought into contact with the back side of the intermediate transfer belt 10 by the secondary transfer means 231. The intermediate transfer belt 10 formed by being pressed to the side and the secondary transfer means 231 are configured to collectively transfer onto a sheet conveyed to the nip portion.
In the secondary transfer nip portion, the sheet is charged by the voltage applied to the secondary transfer unit 231. In the case of the negative positive developing method in which the photosensitive member is charged to minus (−), the charging polarity of the toner is (−), and the voltage applied to the secondary transfer unit 231 is plus (+) having a polarity opposite to that of the toner. As a result, the back side of the sheet is charged (+) and the front side is charged (-). When the sheet has a high resistance, this charged state is maintained even after passing through the secondary transfer nip portion.
Therefore, the following abnormal image may be seen in the image on the sheet due to the peeling discharge generated between the sheet that has passed through the secondary transfer nip and the surface of the intermediate transfer belt 10. FIG. 15 is a top view of the sheet on which the solid toner image is transferred, and FIG. 16 is a perspective view thereof. In the solid portion where the toner adhesion amount is large as shown in the figure, trailing edge dust is seen in which the toner present at the corners of the layered toner portion T is scattered downstream in the paper transport direction. At this time, a slight gap is seen between the toner portion T and the rear end dust.

This phenomenon of trailing edge dust can be explained as follows.
FIG. 17 is a diagram for explaining the phenomenon of rear end dust. In the secondary transfer nip portion, the toner image T transferred onto the paper P has a large amount of (−) true charge and a high (−) potential. (−) Electric charge is obtained in the background portion of the paper P by the peeling discharge, but the electric potential is not generated as in the former, and the electric discharge does not start in the secondary transfer nip portion. Also, dust does not occur unless the toner amount is very large.
Next, in the exit of the secondary transfer nip portion, that is, in a region where the paper P and the intermediate transfer belt 10 are separated, a separation discharge occurs between the two, and this separation discharge region is as shown in FIG. It can be divided into four. In the background portion (α portion) on the upstream side in the paper transport direction from the toner portion T, charge exchange by normal peeling discharge is performed without abnormality. In the toner portion T (β portion), because of the high potential of the toner portion T itself, the discharge path is bypassed or the discharge itself is blocked. Subsequently, when the paper P is conveyed, discharge starts in the background portion (γ portion) on the downstream side of the toner portion T to which the discharge path bypasses. At this time, since the (−) charge in the β portion is added, the discharge amount is large and partially penetrates the toner (δ portion) at the trailing edge. In addition, since this discharge is received also in the vicinity of the background portion (ε portion), the potential rise starts.
In these charge states, the exchange of charge amounts and potentials in the background portion (γ portion) excluding the rear end (δ portion) of the toner portion T and its vicinity (ε portion) and the potential are shown in FIGS. Show. A high potential is generated between the toner at the rear end (δ portion) of the toner portion T and the downstream background portion (γ portion), and the toner in the δ portion is floated by a slight shock and scattered to the γ portion. This is recognized as rear end dust, and it can be explained that a slight gap is formed between the rear end dust and the toner portion T as shown in FIG.

For the charge adjustment of the toner part after passing through the transfer part, the following apparatus has been proposed. In Patent Document 1, after the paper on which the toner image is transferred is separated from the photosensitive belt, the corona generating device disposed above the paper supplies a charge having a polarity opposite to that of the toner image to the paper. An image forming apparatus is described in which a corona generating device disposed below supplies a charge having the same polarity as a toner image to the back surface of a sheet. Thereby, the toner image on the paper is neutralized.
Patent Document 2 discloses that a part of the electric charge generated by the pre-cleaning static eliminator that neutralizes the surface of the photosensitive member after the toner image on the photosensitive member is transferred to the intermediate transfer member or the sheet. An image forming apparatus configured to be discharged also to the upper toner portion is described. At this time, an AC bias voltage is applied to the pre-cleaning static eliminator. When the charge of the intermediate transfer member or paper and the charge of the toner part do not balance and either becomes excessive, the charge of the missing polarity is attracted by the AC bias of the static eliminator before cleaning, The surface charge is balanced.

JP-A-4-226484 JP 2001-154548 A

  However, Patent Document 1 does not aim at the exit of the transfer nip portion of the paper, and therefore does not consider the peeling discharge phenomenon that occurs on the paper. In Patent Document 2, the charge of the toner portion is not positively adjusted. Further, the relationship with the resistance value of the paper is not taken into consideration.

  In view of the above problems, it is an object of the present invention to provide an image forming method and an image forming apparatus that take a better measure against image dust in a transfer portion and output a high-quality image.

In order to solve the above problems, the present invention is characterized by the following.
1. A latent image forming process for forming an electrostatic latent image on the image carrier, a developing process for supplying toner to the electrostatic latent image and developing, and a toner image formed on the image carrier is transferred to an intermediate transfer member In the image forming method having a primary transfer step and a secondary transfer step of transferring the toner image on the intermediate transfer member to the paper, the secondary transfer is performed on the image surface side of the paper immediately after passing through the secondary transfer step. The image forming method includes a step of applying an ion wind having the same polarity as that received by the image surface of the paper after passing through the transfer step.

2. An image carrier that carries a latent image, a latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that supplies toner to the electrostatic latent image on the image carrier and develops the image, and an image An intermediate transfer member that transfers and holds the toner image on the carrier, a primary transfer unit that transfers the toner image on the image carrier to the intermediate transfer member, and a toner image that the intermediate transfer member holds on the sheet And a secondary transfer unit having a secondary transfer member that forms a secondary transfer nip with the intermediate transfer member when a voltage is applied to the secondary transfer nip. The image forming apparatus includes an ionic wind applying unit that applies an ionic wind having the same polarity as the toner on the paper to the image surface side of the paper immediately after passing through.

3. In the image forming apparatus, the ion wind applying unit includes an electrode for generating ions, an intake port for taking in air, and an exhaust port for discharging the ion wind.
4). In the image forming apparatus, an electrode for generating ions of the ion wind applying unit is in a saw blade shape or a wire shape.
5). In the image forming apparatus, the ion wind applying unit includes a cover in the vicinity of an electrode for generating ions.

6). In the image forming apparatus, the ion wind applying unit includes an air volume control unit that controls an air volume.
7). In the image forming apparatus, the air volume control unit includes a filter disposed at an outlet of the ion wind applying unit.
8). In the image forming apparatus, the ion wind applying unit includes a charge amount adjusting unit that controls a charge amount.

9. In the image forming apparatus, the ion wind applying unit includes an electrode cleaning member that cleans an electrode that generates ions.
10. In the image forming apparatus, the ion wind applying unit may vary a polarity of a bias applied to an electrode that generates ions.

11. In the image forming apparatus, the electrode that generates ions of the ion wind applying unit may be a solid discharge element.

12 In the image forming apparatus, the ion wind applying unit determines whether or not the operation is possible based on a resistance of a sheet passing through the secondary transfer unit.
13. In the image forming apparatus, the resistance of the sheet passing through the secondary transfer unit is detected by a current detection sensor provided at one end of a circuit through which a transfer bias flows.
14 In the image forming apparatus, the resistance of the sheet passing through the secondary transfer unit is detected by a current detection sensor provided on the sheet conveyance path.

  According to the present invention, image dust generated when a toner image on an intermediate transfer member is transferred onto a sheet can be effectively prevented, and a high-quality image can be provided.

Embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an image forming apparatus according to the present invention. FIG. 2 is an enlarged view showing a main part of the image forming apparatus shown in FIG.
In FIG. 1, reference numeral 100 denotes a copying apparatus main body, 200 denotes a paper feed table on which the copying apparatus is placed, 300 denotes a scanner mounted on the copying apparatus main body 100, and 400 denotes an automatic document feeder (ADF) mounted thereon.
The copying apparatus main body 100 includes four image forming units 18 each having various units for performing an electrophotographic process such as a charging unit 60, a developing unit 61, and a cleaning unit 63 around a photosensitive member 40 as an image carrier. A tandem type image forming apparatus 20 is provided in parallel.
The photoreceptor 40 is in the form of a drum in which a photosensitive organic layer is applied to an element tube such as aluminum to form a photosensitive layer. The charging means 60 is formed in a roller shape in the illustrated example, and charges the photoconductor 40 by contacting the photoconductor 40 and applying a voltage. The developing means 61 may use a one-component developer, but in the illustrated example, a two-component developer composed of a magnetic carrier and a non-magnetic toner is used. The developing unit includes a developing unit that carries the developer on the developing sleeve and supplies the developer to the latent image portion on the surface of the photoreceptor 40, and an agitating unit that agitates the developer and supplies the developer on the developing sleeve. The cleaning means 63 is provided with a cleaning member such as a polyurethane rubber cleaning blade, a conductive fur brush, etc., which is disposed in contact with the photoreceptor 40, for example, a polyurethane rubber cleaning blade disposed with its tip pressed against the photoreceptor 40. It becomes.

Above the tandem image forming apparatus 20, there is provided an exposure apparatus 21 that exposes the photoreceptor 40 with laser light based on image information to form a latent image. An intermediate transfer belt 10 made of an endless belt member is provided at a position facing each photoconductor 40 of the tandem type image forming apparatus. The intermediate transfer portion belt 10 is a single-layer belt made of a single layer polyimide material as a base, and is configured to be wound around support rollers 14, 15, 16 and rotated and conveyed clockwise in the drawing.
A primary transfer unit 62 for transferring the toner images of the respective colors formed on the photoconductor 40 to the intermediate transfer belt 10 is disposed at a position facing the photoconductor 40 via the intermediate transfer belt 10. The primary transfer unit 62 is formed in a roller shape and is configured to be applied with a predetermined voltage from a power source (not shown). However, the primary transfer unit 62 is not limited to the roller shape, and may be a brush or a non-contact corona charger.

A secondary transfer device 22 that collectively transfers the toner images superimposed on the intermediate transfer belt 10 onto a sheet conveyed from the paper feed table 200 is disposed below the intermediate transfer belt 10. The secondary transfer device 22 is configured by spanning a secondary transfer belt 24, which is an endless belt, between two rollers 231, 232, and is disposed by pressing against the support roller 16 via the intermediate transfer belt 10. The toner image on the transfer belt 10 is transferred to a sheet. The secondary transfer belt 24 is a transfer transport belt that also serves as a paper transport. Next to the secondary transfer device 22, a fixing device 25 for fixing the image on the paper is provided. The fixing device 25 is configured by pressing a pressure roller 27 against the fixing roller 26.
Further, a reversing device 28 for reversing the paper so as to record images on both sides of the paper is provided below the secondary transfer device 22 and the fixing device 25.

The image forming apparatus of the present invention includes an ion wind applying unit 110 that applies an ion wind to the image surface side of a sheet immediately after passing through the secondary transfer nip portion. In FIG. 1 and FIG. 2, it is located between the intermediate transfer belt 10 and the secondary transfer belt 24.
3 and 4 are views for explaining the configuration of the ion wind applying means 110. FIG. 3 is a sectional view, and FIG. 4 is a perspective view. The ion wind applying means 110 includes an electrode 111 that generates ions in a case 112. As the electrode 111, an electrode generally used as an ozonizer or a charging member for electrophotography can be used. In this embodiment, the saw-tooth electrode 111 is made of a material such as pure copper or phosphor bronze and has a needle tip pitch of 3 mm and a needle angle of 60 degrees. The thickness of the electrode is preferably 0.3 mm or less, more preferably 0.15 mm or less, which stabilizes the discharge. The tip of the electrode 111 is made sufficiently straight. In the case of long-term use, foreign matter such as SiO ₂ which is a toner additive may be formed on the needle tip or paper dust may be stuck, but it is exchanged at an appropriate timing to satisfy the mechanical life. Note that the tip corrosion of the needle can be intentionally performed to reduce the amount of SiO ₂ generated.

  Here, the case 112 is formed using a material such as ABS having a medium resistance to a high resistance. A low-resistance material is short-circuited and cannot be used. Further, if the insulating property is too high, it is not preferable because the internal charges are difficult to disappear and the charge cannot be removed. However, in this case, the charge can be removed by applying a positive / negative bias ion wind. The wall of the case 112 may be surrounded by GND. Although not shown, an airflow adjustment guide may be placed inside.

  The electrode 111 is connected to a high voltage bias device 118 for performing an air breakdown. The high voltage bias device 118 applies a voltage of −4 to −7 kV to the electrode 111, and a current of several tens to several hundred μA flows. Then, discharge occurs at the needle tip 111a of the electrode 111. At this time, air can be urged by sending air to the needle point 111a which is a discharge point. The amount of air varies depending on the amount of ions to be generated, but air inside the apparatus may be taken in from the suction port 115, or air may be taken in from an external means (compressor or the like) as necessary. .

The ionic wind generated by the ionic wind applying means 110 is discharged from the discharge port 113 toward the secondary transfer nip portion. FIG. 5 is a conceptual diagram of the operation of the ion wind applying means 110. The ionic wind conveyed to the secondary transfer nip portion by the ionic wind applying means 110 is absorbed by the ground surface of the paper P with a small amount, and increases the potential V of the α portion and the γ portion. On the other hand, in the toner portion T (β portion), because of the high potential of the toner portion T itself, the discharge path is bypassed or the discharge itself is prevented.
Subsequently, when the sheet is conveyed, discharge starts in the background portion (γ portion) on the downstream side of the toner portion T to which the discharge path bypasses. At this time, since the (−) charge in the β portion is added, the discharge amount is large, and the potential at the trailing edge (δ portion) of the toner portion T rises. Further, since this discharge is received also in the vicinity of the background portion (ε portion), the potential rises. As can be seen from FIGS. 5B and 5C, the potential gap between Vδ and Vγ is reduced by reducing the potential gap between the background portion (γ portion) and the toner portion T (β portion), and the trailing edge dust is reduced. Is done.

  Here, the difference between a normal static elimination apparatus and the ion wind provision means 110 of this invention is demonstrated. FIG. 18 is a diagram illustrating a configuration of a normal static eliminator. The neutralization device 120 is a device that discharges to the non-image surface side of the paper P, and neutralizes the (+) charge on the back surface of the paper due to the transfer electric field by the (−) charge from the static elimination electrode. If the resistance of the paper P is medium resistance, the charge on the back side of the paper may reach the image surface through the paper. However, if the paper P has a high resistance, the charge on the back side of the paper does not affect the image surface. The effect of adjusting the potential difference between the background portion and the toner portion intended by the present invention cannot be obtained at all, and cannot be used as a countermeasure against transfer dust.

  The electrode for generating ions may be in the form of a wire. FIG. 6 is a schematic configuration diagram of the ion wind applying means 110 using a wire charger as an electrode. The wire 130 is preferably used for an ordinary charging member, and electro-polishing with a diameter of 150 μm or less, a carbon-coated tungsten extension wire, or the like can be used. Since the wire 130 has a risk of disconnection due to self-excited vibration due to electric discharge, a support member 131 is placed in the center to suppress vibration. Here, felt or the like is used. Note that when the wire 130 is used, the amount of ozone generated increases, and therefore an ozone decomposing agent or the like is installed inside the case 112 as necessary.

  As described above, the ion wind applying unit 110 generates (−) charge having the same polarity as the toner at the discharge point 111a. However, the secondary transfer residual toner remaining on the adjacent intermediate transfer belt 10 is strong. (+) Polarity. For this reason, if the electrode 111 (or 130) is not covered with the case 112, toner of (+) polarity collects at the discharge point 111a and is contaminated, which may deteriorate the discharge state. Therefore, the electrodes 111 and 130 are covered with a case 112 as shown in FIGS. Further, the case 112 may be formed of an insulating material, and the case 112 may be charged to (−), and dirt may be attached thereto. Thereby, the electrode life can be extended.

Air necessary for discharging is taken into the ion wind applying means 110 from the inside of the apparatus or from the outside as required. FIG. 7 is a diagram showing the relationship between the air volume of the ion wind and the transfer dust. If the amount of air taken in is small and the amount of ion air is small, there is no effect on the transfer dust, and the transfer dust rank is low. Increasing the ion air volume has the effect of suppressing transfer dust, but if the air volume is too large, image blow-off occurs, resulting in failure. Therefore, it is necessary to provide ion air volume control means for appropriately controlling the air volume of the ion wind.
In FIG. 3, a filter 114 is provided at the tip of the discharge port 113 so as to limit the ion air volume. The filter 114 can be a wire, a coarse sponge, or the like. As the sponge, Si sponge is preferable from the viewpoint of ozone resistance. By selecting the coarseness of the filter 114, it is possible to obtain an optimum ion flow rate. In addition, although not shown, the amount of air entering the suction port 115 may be adjusted using, for example, a motor.

In addition, the ion wind applying unit 110 includes a charge amount adjusting unit that controls the amount of charge. For example, when the paper is a thick paper, the resistance of the paper P is particularly high, so it is necessary to increase the amount of charge applied to the image surface. Therefore, for example, after detecting thick paper by user manual detection or automatic detection in the paper feed tray, the setting value of the high voltage bias device 118 of the ion wind applying unit 110 is changed to increase the amount of ion generation. .
Further, as shown in FIG. 3, the discharge filter 114 may be formed of a conductive member, connected to the intermediate pressure bias device 119, and a bias may be applied to the filter 114 to adjust the charge amount. Good. FIG. 8 shows the ion airflow when three types of bias applied to the filter 114 are different. Thereby, it turns out that the air volume and the ion delivery volume can be controlled separately.

  FIG. 9 is a diagram showing another configuration of the ion wind applying means 110. In this configuration, the high-voltage bias device 118b can change the polarity of the bias applied to the electrode 111 between positive and negative. Dirt such as toner electrically attached to the electrode 111 after long-term use can be removed from the surface of the electrode 111 by reversing the bias applied to the electrode 111 between sheets on which image formation is not performed. Thereby, the lifetime of the electrode 111 can be extended.

  Alternatively, the electrode 111 may be provided with a cleaning member. FIG. 10 is a diagram illustrating a configuration of the electrode cleaning member. The electrode cleaning member 180 is installed on the frame body 182 so that the sponge-like cleaning portion 181 contacts both side surfaces of the sawtooth electrode, and the discharge point 111a of the electrode 111 is cleaned at a predetermined timing.

  As the ion wind applying means 110 of the present invention, a solid discharge element can be used in addition to the saw-shaped and wire-shaped electrodes shown in FIGS. FIG. 11 is a diagram showing a configuration in which the electrode of the ion wind applying means 110 is a solid discharge element. The electrode 190 using a solid discharge element is one in which an ozonizer is used for a two-phase AC power source. Since the electrode is resistant to contamination of the discharge part, no electrode cleaning member or the like is required.

  By the way, when the sheet has low resistance, it is meaningless to operate the ion wind applying means 110. In particular, when the resistance of the sheet is extremely lowered, the application bias of the ion wind applying unit 110 may enter the secondary transfer portion and may hinder the transfer, which is rather harmful. Therefore, it is preferable that the ion wind applying means 110 is operated only during double-sided printing where the resistance of the paper is high or in a low humidity environment.

Further, it may be configured to detect the resistance of the sheet and determine whether or not to operate the sheet.
For example, as shown in FIG. 12, a current detection sensor 235 that detects the current of the opposing roller 16 of the secondary transfer roller 231 is provided. When the high-voltage bias device 118 of the ion wind applying unit 110 is activated and the ion wind is applied to the image surface of the paper, the current detection sensor 235 confirms the fluctuation of the current of the counter roller 16. Therefore, it is determined that the influence of the application bias of the ion wind applying unit 110 is generated through the sheet, and the operation of the ion wind applying unit 110 is stopped. Thereby, it is possible to prevent noise from being generated in the secondary transfer bias due to the influence of the ion wind and affecting the image.

  FIG. 13 shows another means for detecting the resistance of the paper, and is an example in which detection means is provided in the registration rollers 49a and 49b. 49a is a bias roller, and 49b is a detection roller provided with a current detection sensor 491. A current value obtained by the current detection sensor 491 is A / D converted, calculated, and determined by the MPU to determine whether or not to operate the high-voltage bias device 118 of the ion wind applying unit 110. As in the previous example, it is possible to prevent the secondary transfer bias from generating noise due to the influence of the ion wind and affecting the image.

  In the above embodiment, the secondary transfer unit is configured by the intermediate transfer belt 10 and the secondary transfer roller 231 that contacts the intermediate transfer belt 10 via the secondary transfer belt 24. The present invention is not limited to this, and the secondary transfer unit may have a configuration in which the secondary transfer roller 231 directly contacts the intermediate transfer belt 10.

  The present invention can also be applied to a repulsive transfer system. In the repulsive transfer method, a (−) bias is applied to the counter roller 16 side, and the secondary transfer roller 231 is grounded. The magnitude of the bias applied between the two is about the same as that of normal transfer. Since the back surface of the sheet is given a bias in the (+) direction from the grounded secondary transfer roller 231, the charging direction of the sheet is the same as that in the normal transfer. Therefore, the (−) bias is applied from the opposite roller 16 side. Will be given. The ion wind applying means 110 of the present invention can effectively prevent the trailing edge of the image on the paper after passing through the secondary transfer nip portion. Note that the specifications of the medium-pressure bias device 119 need to be changed to a predetermined power supply voltage for repulsive transfer.

The operation of the image forming apparatus of the present invention configured as described above is as follows.
First, a document is set on the document table 30 of the automatic document feeder 400, or the automatic document feeder 400 is opened and a document is set on the contact glass 32 of the scanner 300, and the automatic document feeder 400 is closed. Hold it down.
When a start switch (not shown) is pressed, when the document is set on the automatic document feeder 400, the document is transported and moved onto the contact glass 32, and then the document is set on the other contact glass 32. At that time, the scanner 300 is immediately driven to travel the first traveling body 33 and the second traveling body 34. Then, the first traveling body 33 emits light from the light source and further reflects the reflected light from the document surface toward the second traveling body 34 and reflects by the mirror of the second traveling body 34 and passes through the imaging lens 35. The document is placed in the reading sensor 36 and the original content is read.

  When a start switch (not shown) is pressed, one of the support rollers 14, 15 and 16 is rotationally driven by a drive motor (not shown), the other two support rollers are driven to rotate, and the intermediate transfer belt 10 is rotated and conveyed. To do. At the same time, the individual image forming means 18 rotates the photoconductor 40 to form black, yellow, magenta, and cyan monochrome images on each photoconductor 40. Then, along with the conveyance of the intermediate transfer belt 10, the monochrome images are sequentially transferred to form a composite color image on the intermediate transfer belt 10.

On the other hand, when a start switch (not shown) is pressed, one of the paper feed rollers 42 of the paper feed table 200 is selectively rotated, and the sheet is fed out from one of the paper feed cassettes 44 provided in multiple stages in the paper bank 43, and the separation roller 45. Then, the sheets are separated one by one into the paper feed path 46, transported by the transport roller 47, guided to the paper feed path 48 in the copying machine main body 100, and abutted against the registration roller 49 and stopped.
Alternatively, the sheet feed roller 50 is rotated to feed out the sheets on the manual feed tray 51, separated one by one by the separation roller 52, put into the manual feed path 53, and abutted against the registration roller 49 and stopped.
Then, the registration roller 49 is rotated in synchronization with the composite color image on the intermediate transfer belt 10, the sheet is fed between the intermediate transfer belt 10 and the secondary transfer device 22, and is transferred by the secondary transfer device 22. A color image is recorded on the sheet.

The image-transferred sheet is conveyed by the secondary transfer device 22 and sent to the fixing device 25. The fixing device 25 applies heat and pressure to fix the transferred image, and then the switching roller 55 is used to switch the discharge image. The paper is discharged at 56 and stacked on the paper discharge tray 57. Alternatively, it is switched by the switching claw 55 and put into the sheet reversing device 28, where it is reversed and guided again to the transfer position, and an image is recorded also on the back surface, and then discharged onto the discharge tray 57 by the discharge roller 56.
On the other hand, the intermediate transfer belt 10 after the image transfer is removed by the intermediate transfer belt cleaning device 17 to remove residual toner remaining on the intermediate transfer belt 10 after the image transfer, so that the tandem image forming apparatus 20 can prepare for the image formation again.

1 is a schematic configuration diagram of an image forming apparatus according to the present invention. FIG. 2 is an enlarged view showing a main part of the image forming apparatus in FIG. 1. It is sectional drawing explaining the structure of an ion wind provision means. It is a perspective view explaining the structure of an ion wind provision means. It is a conceptual diagram of operation | movement of an ion wind provision means. It is a schematic block diagram of the ion wind provision means which used the wire charger as an electrode. It is a figure which shows the relationship between the volume of ion wind, and transfer dust. The ion air flow when three types of bias applied to the filter are different is shown. It is a figure which shows another structure of an ion wind provision means. It is a figure which shows the structure of an electrode cleaning member. It is a figure which shows the structure which used the electrode of the ion wind provision means as the solid discharge element. It is a figure which shows the structure which provided the means to detect resistance of a paper. It is a figure which shows the structure which provided another means to detect the resistance of a paper. 1 is a diagram illustrating a configuration of a tandem type image forming apparatus including an intermediate transfer member. FIG. 4 is a diagram of a sheet onto which a toner image has been transferred, viewed from above. FIG. 6 is a perspective view of a sheet on which a toner image is transferred. It is a figure explaining the phenomenon of rear end dust. It is a figure which shows the structure of the normal static elimination apparatus.

Explanation of symbols

10 Intermediate transfer belt 22 Secondary transfer device 231 Secondary transfer roller 232 Support roller 24 Secondary transfer belt 40 Image carrier (photosensitive member)
61 Developing means 110 Ion wind applying means 111 Electrode 112 Case 113 Suction port 114 Filter 115 Discharge port 118 High voltage bias device 119 Medium pressure bias device 180 Electrode cleaning member

Claims (14)

A latent image forming process for forming an electrostatic latent image on the image carrier, a developing process for supplying toner to the electrostatic latent image and developing, and a toner image formed on the image carrier is transferred to an intermediate transfer member In an image forming method comprising: a primary transfer step, and a secondary transfer step of transferring a toner image on an intermediate transfer member onto a sheet,
An image characterized in that an ion wind having the same polarity as that received by the image surface of the paper after passing through the secondary transfer step is provided on the image surface side of the paper immediately after passing through the secondary transfer step. Forming method. An image carrier that carries a latent image, a latent image forming unit that forms an electrostatic latent image on the image carrier, a developing unit that supplies toner to the electrostatic latent image on the image carrier and develops the image, and an image An intermediate transfer member that transfers and holds the toner image on the carrier, a primary transfer unit that transfers the toner image on the image carrier to the intermediate transfer member, and a toner image that the intermediate transfer member holds on the sheet A secondary transfer unit having a secondary transfer member that is applied with a voltage and forms a secondary transfer nip portion with the intermediate transfer member.
An image forming apparatus comprising: an ion wind imparting unit that imparts an ion wind having the same polarity as the toner on the paper on the image surface side of the paper immediately after passing through the secondary transfer nip portion.   The image forming apparatus according to claim 2, wherein the ion wind applying unit includes an electrode that generates ions, a suction port that takes in air, and a discharge port that discharges the ion wind. .   The image forming apparatus according to claim 3, wherein an electrode that generates ions of the ion wind applying unit has a saw blade shape or a wire shape.   The image forming apparatus according to claim 4, wherein the ion wind applying unit includes a cover in the vicinity of an electrode that generates ions.   6. The image forming apparatus according to claim 3, wherein the ion wind applying unit includes an air volume control unit that controls an air volume.   The image forming apparatus according to claim 6, wherein the air volume control unit includes a filter disposed at an outlet of the ion wind applying unit.   The image forming apparatus according to claim 2, wherein the ion wind applying unit includes a charge amount adjusting unit that controls a charge amount.   9. The image forming apparatus according to claim 3, wherein the ion wind applying unit includes an electrode cleaning member that cleans an electrode that generates ions. 10.   10. The image forming apparatus according to claim 3, wherein the ion wind applying unit has a variable polarity of a bias applied to an electrode that generates ions. 11.   The image forming apparatus according to claim 3, wherein an electrode that generates ions of the ion wind applying unit is a solid discharge element.   6. The image forming apparatus according to claim 3, wherein the ion wind applying unit determines whether or not the operation can be performed based on a resistance of a sheet passing through the secondary transfer unit.   13. The image forming apparatus according to claim 12, wherein the resistance of the sheet passing through the secondary transfer unit is detected by a current detection sensor provided at one end of a circuit through which a transfer bias flows.   The image forming apparatus according to claim 12, wherein a resistance of the sheet passing through the secondary transfer unit is detected by a current detection sensor provided on the sheet conveyance path.

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