JP5267865B2 - Electrostatic recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrostatic recording device that stably achieves high image quality transfer free from defects in the entire printing area of various recording media without being affected by the environment and the width and thickness of a recording medium and that has long service life and is inexpensive. <P>SOLUTION: The electrostatic recording device includes: a transfer means; a continuous recording medium; a conveying guide that guides a recording medium to an area between a toner image carrier and a transfer mechanism member by coming into contact with the recording medium at a position before the recording medium comes into contact with the toner image carrier; a transfer mechanism member having a dielectric layer on the outermost surface of the transfer means and having a roller form; and a transfer mechanism member charging means for charging the surface of the transfer mechanism member from outside. The electrostatic recording device has a charge imparting means which supplies charges of a polarity opposite to the polarity of toner to the surface of recording medium, which is opposite to the surface in contact with the toner image carrier, in a non-contact manner with the recording medium, in an area where the recording medium is brought into contact with the toner image carrier at the downstream side of the conveying guide and at the upstream side of the transfer means. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electrostatic recording apparatus such as an electrophotographic printer or copying machine using continuous paper, and in particular, a toner image is transferred from an image carrier to a recording medium by contacting a surface charged roller with the recording medium. The present invention relates to image quality improvement in a transfer device that performs transfer.

  Continuous paper printers using the electrophotographic method are used for multi-purpose printing such as direct mail, invoices, manuals, books, etc. because they can print at a high speed exceeding 1000 mm / s with few obstacles such as recording media jams. It has come to be. With the expansion of applications used, there are increasing opportunities to use recording media with large surface irregularities such as rough paper. When such recording media are used, toner images such as photoreceptors and intermediate transfer media are used. When transferring a toner image from a carrier to a recording medium, there is a problem that image defects are likely to occur due to poor adhesion.

  Also, when performing double-sided printing with a continuous paper printer, a tandem method is generally used in which two printers are arranged side by side and the recording medium after printing is reversed, and the back side is printed with the second device. However, in this case, even on a recording medium with few surface irregularities, the recording medium shrinks and generates irregularities in the first fixing, so that image defects are likely to occur during the second transfer.

As a transfer method capable of ensuring the adhesion between the recording medium and the toner image carrier, the toner image is transferred to the recording medium by electrostatic force while pressing the recording medium against the toner image carrier with a transfer mechanism member such as a roller or a belt. Roller transfer and belt transfer systems are generally known. As means for generating an electrostatic force, a method of directly applying a voltage or current to a transfer mechanism member (core metal application method) and a method of charging a dielectric layer on the surface of the transfer mechanism member (external charging method) are known. Yes. (JP 51-151544, JP 49-18335, etc.)
The cored bar application method is a method generally used in medium- and low-speed cut sheet printers, but it applies a necessary voltage to the back surface of the recording medium via a transfer mechanism member such as an elastic roller or belt. Since the resistance value range of the elastic roller and the belt is limited because the current needs to be supplied, the performance fluctuation such as transfer efficiency and image quality defect is large due to the change of resistance value over time and environment, and Since the range has a relatively low resistance, the value of the current flowing through the transfer medium varies greatly depending on the presence or absence of the recording medium, and the voltage or current value applied to the transfer medium must be adjusted according to the width of the recording medium. In addition, since the resistance range of the transfer medium is limited, the material used is also limited, and it is difficult to maintain performance over a long period of time.

  On the other hand, in the external charging method in which a dielectric layer is provided on the elastic layer of the transfer mechanism member and a predetermined charge is made by supplying a charge to the surface of the dielectric layer using a corona charger or a roller charger, a photoconductor Even in continuous paper printers where the width exceeds 500 mm and the area outside the recording medium becomes very large depending on the recording medium used, a large amount of current flows in the area outside the recording medium as in the core metal application method, and the recording medium is required. There is no problem that a strong electric field cannot be formed, and a material having excellent durability such as PFA can be used for the dielectric layer on the surface, which is advantageous from the viewpoint of durability.

  However, in the external charging method, the dielectric layer on the surface of the transfer mechanism member is charged by a charger, and the charge accumulated in the dielectric layer is conveyed to the contact portion (transfer nip portion) with the recording medium by the rotation of the transfer mechanism member. The transfer is performed by supplying the recording medium to the recording medium at the transfer nip, and only a part of the charge supplied from the charger to the dielectric layer of the transfer mechanism member moves to the recording medium at the transfer nip. The amount of charge supplied to the layer increases, and depending on the dielectric constant and film thickness setting of the dielectric layer, the charged potential of the dielectric layer may be higher than that of the mandrel application method.

  Regardless of the external charging method, when the potential of the transfer mechanism member is high, the recording medium and the toner image are carried before and after the transfer nip portion (hereinafter referred to as the transfer nip portion), which is a region where the recording medium contacts the toner carrier. Conventionally, there has been known a problem that image quality after transfer is deteriorated due to discharge in the gap with the body or toner on the toner image carrier moving to the recording medium in the presence of the gap. .

  For example, in Patent Document 3, an auxiliary transfer roller and a main transfer roller are disposed on a photosensitive drum via a transfer belt, and a main transfer is performed while a low voltage is applied to the auxiliary transfer roller so as not to generate a high electric field. A method of applying a high transfer voltage for realizing sufficient transfer to a roller is disclosed.

  Further, in Patent Document 4, a voltage application member that is in contact with the recording medium is provided at a position where there is a gap between the recording medium before and after the nip and the toner image carrier, and the surface potential of the annular member increases as the distance from the opposing transfer position increases. A configuration is disclosed that has a distribution in which the difference between and gradually decreases.

  In Patent Document 5, a charge amount adjusting unit that adjusts the charge amount of toner according to the properties of the recording medium, and a toner transfer of the recording medium according to the charge amount of toner adjusted by the charge amount adjusting unit. A charge imparting means for imparting charge in a state where there is a gap between the recording medium and the toner carrier on the surface, and a control means for controlling the amount of charge on the surface of the transfer material imparted by the charge imparting means. A method is disclosed.

Japanese Patent Laid-Open No. 51-151544 Japanese Patent Laid-Open No. 49-18335 JP 2004-246323 A Japanese Patent Laid-Open No. 2007-3880 JP 2008-107692 A

  In the case of a continuous paper printer, since printing is performed on a continuous recording medium, the feeding accuracy of a member in contact with the recording medium greatly affects the running performance of the recording medium.

  As described in Patent Documents 3 and 4, when a method of pressing the recording medium against the toner image carrier with an auxiliary roller is used, the recording paper is meandered by the inclination of the auxiliary roller shaft, eccentricity, load deviation, etc. Since it is difficult to suppress the change in the gap between the recording medium and the toner carrier between the rollers due to the speed difference of the transfer roller, it is desirable to use a system that prevents image quality deterioration near the nip without pressing the rotating member against the recording medium.

  Also, as in Patent Document 5, in the method of applying a voltage to the opposite side of the recording surface with a gap between the toner image carrier and the recording medium, the transfer roller from the auxiliary roller to various recording media It is difficult to stably form an electric field that does not cause discharge and does not transfer toner onto a recording medium in a state where there is a gap between the regions reaching the surface.

  As in Patent Document 6, even when a charge is applied to the surface of the recording medium in a state where there is a gap between the toner carrier and the recording medium, a discharge is generated between the region from the charge applying unit to the transfer roller. It is difficult to stably form an electric field that does not occur and does not cause toner to be transferred to a recording medium in the presence of voids.

  The object of the present invention is to solve the above-mentioned problems, and to transfer high-quality images without defects over the entire printing area at high speed onto various continuous recording media such as recording media with large unevenness without affecting the width, thickness, and environment of the recording medium. It is an object of the present invention to provide a long-life and inexpensive electrostatic recording apparatus that can be stably performed.

In order to achieve the above object, the first means of the present invention is a transfer means for transferring a toner image from a toner image carrier to a recording medium, a continuous recording medium, and before the recording medium comes into contact with the toner image carrier. A conveyance guide for contacting the recording medium between the toner image carrier and the transfer mechanism member in contact with the recording medium at the position, and a transfer mechanism formed in a roller shape having a dielectric layer on the outermost surface of the transfer means In an electrostatic recording apparatus comprising a member and a transfer mechanism member charging means for charging the surface of the transfer mechanism member from the outside,
In a region where the recording medium is in contact with the toner image carrier on the downstream side of the conveyance guide and upstream of the transfer unit, the surface of the recording medium opposite to the surface in contact with the toner image carrier is not in contact with the recording medium. And a charge applying means for supplying a charge having a polarity opposite to the toner polarity.

  The second means of the present invention is characterized in that, in the first means, the conveyance guide is grounded.

According to a third means of the present invention, in the first means, a voltage having a polarity opposite to the toner polarity is applied to the conveyance guide.

According to a fourth means of the present invention, the transfer means for transferring the toner image from the toner image carrier to the recording medium, the continuous recording medium, and the recording medium in contact with the recording medium at a position before the recording medium contacts the toner image carrier. A transfer guide for guiding the recording medium between the toner image carrier and the transfer mechanism member, a transfer mechanism member having a dielectric layer on the outermost surface of the transfer means and formed in a roller shape, and a transfer mechanism member In an electrostatic recording apparatus provided with a transfer mechanism member charging means for charging the surface from the outside,
Opposite to the surface of the recording medium that is in contact with the toner image carrier, opposite to the surface of the recording medium that is in contact with the toner image carrier, in contact with the recording medium in a non-contact manner. It has a transfer device provided with a charge imparting means for supplying a charge having a polarity opposite to the toner polarity on the surface of the recording medium.

  A fifth means of the present invention is characterized in that, in the fourth means, a transfer device having the conveyance guide grounded is provided.

According to a sixth means of the present invention, in the fourth means, a voltage having a polarity opposite to the toner polarity is applied to the conveyance guide.

  According to the present invention, even in the external charging transfer system, discharge occurs in the gap between the recording medium and the toner carrier before and after the transfer nip, or the toner on the toner image carrier in the gap exists on the recording medium. Long-lived and inexpensive electrostatic recording that can solve the problem of image quality deterioration after transfer, and can stably transfer with little image quality deterioration without being affected by paper thickness or environment Equipment can be provided.

1 is a schematic configuration diagram of a continuous paper printer according to an embodiment of the present invention. It is sectional drawing of the transfer roller used for the transfer apparatus of the continuous paper printer. It is the schematic which shows operation | movement of the transfer mechanism part of the continuous paper printer. 1 is a schematic configuration diagram of a continuous paper printer according to an embodiment of the present invention. 1 is a schematic configuration diagram of a double-sided continuous paper printer according to an embodiment of the present invention. FIG. 6 is a diagram illustrating a relationship between a transfer roller charging potential and a charge amount supplied to a recording medium. It is a figure which shows the model which approximated the transfer by an external charging system. FIG. 4 is a diagram illustrating a relationship between a recording medium, a transfer roller, and a photoreceptor in transfer potential calculation. It is a figure which shows the calculation result of a space | gap potential difference in case the space | gap of both sides of a paper is equal. It is a figure which shows the calculation result of the photoreceptor side air gap potential difference at the time of winding a paper. It is a figure which shows the calculation result of the transfer roller side space | gap potential difference at the time of winding a paper. It is a figure which shows the image quality evaluation result after transfer which shows the effect of an electric charge provision means. It is a figure which shows the transfer apparatus which is another embodiment of this invention.

  FIG. 1 shows a schematic configuration of a continuous paper printer using a negatively charged OPC photoreceptor 1 as a toner carrier as an embodiment of the present invention.

  A charger 2, an exposure device 3, a developing device 4, and a transfer mechanism unit 6 are disposed on the outer periphery of the photoreceptor 1. After the surface of the photoconductor 1 is uniformly charged to a negative polarity using a scorotron charger as the charger 2, a laser scanning optical system is used as the exposure device 3 and laser light is applied to the surface of the photoconductor 1 according to printing information. Irradiation forms an electrostatic latent image, and the developer 4 attaches toner to the electrostatic latent image to form a toner image.

  The recording medium 16 is conveyed by the tractor 17, and the toner image is transferred from the photoreceptor 1 onto the recording medium 16 by the transfer mechanism unit 6. The toner image on the recording medium 16 is melted and fixed to the recording medium 16 by a fixing device 35 (not shown). The toner remaining on the photosensitive member 1 is removed from the photosensitive member by the cleaner 5.

  Next, the configuration of the transfer mechanism unit 6 will be described. The transfer mechanism 6 supplies a charge to a transfer housing 7 having an upper transport guide 8a and a lower transport guide 8b for guiding the recording medium 16, a transfer roller 9 disposed therein as a transfer mechanism member, and a surface of the transfer roller 9. After the transfer nip portion where the corotron charger 10 as the transfer roller charging means and the transfer roller 9 abuts the photoreceptor 1 via the recording medium 16, the transfer roller potential detecting means 11 and the rotation direction of the transfer roller 9 more than the potential detecting means. A corotron static eliminator 12 is provided on the downstream side.

  The lower conveyance guide 8b is disposed closer to the photoconductor than the contact position between the photoconductor 1 and the transfer roller 9, so that the recording medium 16 can be moved upstream of the transfer nip without pressing the conveyance guide 8b against the photoconductor 1. In this way, a paper feed path is formed so as to be wound around the photosensitive member 1, and the recording medium 16 and the photosensitive member 1 are located between the conveyance guide 8 b and the transfer roller 9 in contact with the photosensitive member 1 through the recording medium 16. A scorotron charger 50 is provided as a charge applying member that applies a charge opposite to the toner on the photosensitive member 1 opposite to the toner transfer surface of the recording medium 16 in a non-contact manner to the surface opposite the contact area. Has been placed.

  The transfer roller 9 has a conductive elastic layer on a conductive shaft, and the outermost surface is formed of a dielectric layer. The transfer roller 9 is supported so as to be rotatable and swingable, and is configured to be able to move away from and in contact with the photoreceptor 1.

  A tractor is disposed on the upstream side and the downstream side of the transfer mechanism unit 6, and a tractor pin is fitted into a feed hole of the recording medium 16 to convey the recording medium 1. The tractor 17 is supported by a tractor shaft (not shown) and transmits the drive from the recording medium transport motor to the tractor 17 to operate the tractor 17.

  When the recording medium transport motor rotates, the transfer roller 9 rotates in synchronization.

  In the present embodiment, the rotation of the transfer roller 9 is linked to the recording medium. However, a separate driving source may be provided or the structure may be rotated by following the recording medium.

  A tensioner 19 is provided between the tractor 17a and the conveyance guide 8b, and the contact state between the transfer roller 9 and the recording medium 16 and the photoreceptor 1 on the upstream side of the transfer roller due to the speed difference of the tractor 17a. To prevent changes. Since there is no member in contact with the recording medium 16 up to the contact portion between the transfer roller 9 and the photosensitive member 1 on the downstream side of the conveyance guide 8b that determines the winding state of the recording medium 16 around the photosensitive member 1, upstream of the transfer nip. The recording medium 16 can be sent stably on the side.

  The transfer roller 9 is pressed against the photoreceptor 1 by a spring (not shown) so that the nip width can be formed with an appropriate pressing force. Further, the transfer mechanism section 6 can be rotated by a cam because of the separation / contact operation of the transfer roller 9.

  Next, the structure of the transfer roller 9 that can be used in the present invention will be described with reference to the sectional view of FIG.

  The transfer roller shaft 9c is supported at both ends by bearings 26, provided with pulleys 21a at its ends, connected to a drive motor 27 via a timing belt 28, and grounded.

  A conductive elastic layer 9b is provided on the transfer roller shaft 9c, and the outermost surface is covered with a dielectric layer 9a.

As a material for the elastic layer 9b, a conductive material is mixed with a general elastic material such as epichlorohydrin rubber, urethane rubber, silicon rubber, fluorine rubber, ethylene propylene rubber, chloroprene rubber, etc. to act as a ground electrode of the dielectric layer 9a. Those having a resistivity of 10 ⁸ Ω · cm or less are preferably used, and those having a resistivity of 10 ⁶ Ω · cm or less are more preferably used.

  As the dielectric layer 9a, a dielectric film typified by a polyester film such as PET or PEN, a film such as PTFE, FEP, PFA, ETFE, or PVDF can be used. It is more preferable to use a good PFA film having a thickness of 30 μm to 100 μm.

  The operation of the transfer mechanism unit 6 configured as described above will be described. FIG. 3 shows the state of the transfer mechanism unit 6 during printing standby and during printing.

  At the time of printing standby, the photosensitive member 1, the recording medium 16, and the transfer roller 9 are in a non-contact state. At the start of printing, the conveyance of the recording medium 16 is started by the tractor 17, and the transfer device housing 7 and the transfer roller 9 start the contact / separation operation with a slight delay from the start of the conveyance operation of the recording medium 16. When the leading position reaches the transfer point, the recording medium 16 comes into contact with the photosensitive member 1 by the pressure of the transfer roller 9 to form an appropriate nip width, and the transfer roller 9 has an appropriate pressing load due to the spring load. Is applied to the photoreceptor 1. On the upstream side of the transfer roller, the recording medium 16 is wound around the photoconductor 1 by the conveyance guide 8b moving to the photoconductor 1 side, and the charge applying member 50 is in the contact area between the recording medium 16 and the photoconductor 1 on the upstream side of the transfer roller. Thus, the recording medium 16 is given a charge having a polarity opposite to that of the toner.

  When the toner image portion on the photosensitive member 1 reaches the transfer nip portion, the transfer roller 9 needs to reach the transfer nip portion with the surface charged to a predetermined potential. Charging by the corotron charger 9 is started in the rotating state, and the surface charged to the specified potential comes into contact with the recording medium 16 at the transfer nip and starts the transfer operation.

  When printing is stopped, the procedure is the reverse of the startup operation, and the next printing operation is prepared.

  In this way, in the external charging type roller transfer, charges are supplied from the outside to the dielectric layer on the roller surface, and the surface of the dielectric layer 9a to which the charges are supplied contacts the back surface of the recording medium 16 at the transfer nip portion. The transfer is performed by forming an electric field between the recording medium 16 and the toner carrier, and all the accumulated charges are not supplied to the recording medium. Depending on the thickness and dielectric constant of the dielectric layer 9a, In order to form an appropriate electric field, the amount of charge supplied to the dielectric layer 9a is larger than that of roller transfer of the mandrel application type.

  FIG. 6 shows the case where single-sided printing is performed with 55 kg paper (simplex) using an external charging type transfer roller using 30 μm PFA for the dielectric layer, and printing is performed on the back side of 55 kg paper once printed. FIG. 6 is an example showing a relationship between a transfer roller charging potential before entering the transfer nip and a charge amount supplied to the recording medium obtained from a potential difference between the transfer rollers before and after passing through the transfer nip when performing (duplex).

  Once the recording medium passes through the fixing machine, the moisture content of the recording medium decreases and the resistance increases, but when transferring to this recording medium, the transfer roller is charged to the same potential as during simplex printing. Since the amount of charge supplied to the recording medium is reduced, the transfer efficiency is lowered.

  Therefore, if the voltage of the transfer roller 9 is set so as to obtain an appropriate transfer efficiency according to the paper type and environment, the surface potential of the transfer roller 9 before passing through the transfer nip portion may become a high voltage. When the transfer roller voltage is increased, the transfer efficiency is partially lowered by discharge between the recording medium 16 and the toner carrier, toner movement in the gap, or discharge in the gap between the recording medium 16 and the transfer roller 9. Or toner scattering occurs, and the image quality after transfer deteriorates.

  In the externally charged roller transfer, as shown in FIG. 7, there is a toner in a void layer on a dielectric layer such as a photosensitive layer or an intermediate transfer belt on a ground surface, and a dielectric layer is similarly formed above the toner layer. It can be approximated by a five-layer dielectric model having a certain recording medium, an air layer, a dielectric layer on the surface of the transfer roller, and a ground layer on the back surface of the dielectric layer.

  The transfer from the photoconductor and the transfer from the intermediate transfer belt or the intermediate transfer drum are basically the same, but in the case of the transfer from the photoconductor, particularly in the case of a system using a reversal development process, no toner adheres. Since the transfer is performed in a state where the background portion is charged to a high potential having the same polarity as the polarity of the toner, the electric field at the transfer nip is particularly large in the background portion, and discharge is likely to occur. For this reason, toner scattering in the peripheral portion of the toner image portion and white spots in the image contour portion due to discharge are particularly likely to occur during transfer from the photoreceptor.

  Therefore, as the initial state, when the surface of the transfer roller and the photosensitive layer are connected in series via the air layer + recording medium + air layer from the state where the surface of the photoconductor is charged to the potential V2 and the surface of the transfer roller to the potential V1. The relationship between the potential difference between the air layers on both sides of the recording medium and the Paschen discharge start potential difference was determined using the above approximate model.

  The transfer roller surface layer thickness was 50 μm, the relative dielectric constant was 2.1, the paper thickness was 80 μm, the relative dielectric constant was 2.3, the photoreceptor film thickness was 32 μm, and the relative dielectric constant was 3.

  As shown in FIG. 8, when the gap between the transfer roller and the paper, the photosensitive member and the paper changes at equal intervals (a), and when the recording medium is wound around the photosensitive member surface which is a toner carrier with a gap of 8 μm and conveyed. In (b), when the potential difference between the gaps on both sides of the recording medium is calculated based on the model of FIG. 7, in the case of (a), as shown in FIG. Although it depends on the photoreceptor potential, it can be seen that when the gap is reduced to about 100 μm, the potential difference exceeds the discharge start voltage, that is, discharge may occur.

  On the other hand, when the recording medium is wound around the toner carrying member, as shown in FIG. 10, the transfer roller potential is 1800 V in the gap between the wound photosensitive member and the recording medium, as in FIG. It can be seen that no discharge occurs.

  However, as shown in FIG. 11, in the gap between the recording medium and the transfer roller when the recording medium is wound around the toner carrier, a discharge is more likely to occur than in FIG. It can be seen that even when the body surface potential is 0V, the battery is discharged.

  In other words, the winding of the recording medium is effective for suppressing the discharge on the toner carrier surface side, but the discharge on the back side is likely to occur, so the transfer roller potential becomes higher as in the external charging method. In the transfer method, it is necessary to consider the suppression of discharge on the back surface.

Therefore, in the present invention, in order to suppress the discharge on both the image surface and the back surface, as shown in FIG. 10, even if the gap is narrowed, it is wound around the surface of the toner carrier before the discharge start potential difference is exceeded. In addition, the discharge on the image surface is suppressed, and the gap electric field is strengthened to prevent the toner from adhering to the recording medium from the toner carrier while the gap is present. In order to suppress discharge in the gap of the recording medium, after the recording medium comes into contact with the toner carrier, the recording medium is provided with a charge having the opposite polarity to the toner, that is, the same polarity as that of the transfer roller, on the back surface of the recording medium. The above problem was solved by reducing the potential difference between the medium and the transfer roller.
In other words, the recording medium 16 is wound around the photosensitive member 1 as a toner carrier by the paper guide 8b, thereby suppressing discharge on the image surface, and is a charge applying member in the region where the recording medium 16 is in contact with the photosensitive member 1. The potential difference between the transfer roller 9 and the recording medium 16 in the gap does not exceed the discharge start voltage by applying a charge having a reverse polarity to the toner, that is, the same polarity as the potential of the transfer roller 9 from the corotron 50 to the recording medium 16 without contact. I did it.

  At this time, the sheet guide 8b is not brought into contact with the photosensitive member 1 as described above, and a member that makes contact with the recording medium 16 is provided between the sheet guide 8b and the contact portion between the transfer roller 9 and the photosensitive member 1. With the configuration in which the recording medium 16 is not provided, due to the effect of the tensioner 19, the recording medium 16 is stably fed from the paper guide 8b while the recording medium 16 is traveling to the transfer roller 9, and the gap in the vicinity of the transfer nip does not fluctuate. Therefore, it is possible to perform transfer with little image quality deterioration.

  FIG. 12 shows a printing speed of 1400 mm / s when the discharge current of the corotron charger 9 for charging the transfer roller 9 and the discharge current of the corotron charger 50 for applying a charge to the transfer mechanism member 16 are changed. The transfer image quality evaluation results are shown, but by applying charge to the recording medium 16, it is possible to greatly expand the range in which image quality deterioration due to solid scattering and discharge does not occur.

  As shown in FIG. 13, the configuration is the same as that of the first embodiment except that the conveyance guide 8b is grounded and the transfer machine housing 7 connected to the upper conveyance guide 8a is grounded via a resistor.

  Since peeling discharge may occur even at the portion where the recording medium 16 peels from the upper conveyance guide 8a, the upper conveyance guide 8a is installed via a 1 MΩ resistor to reduce the electric field change at the time of separation, The conveyance guide 8b is insulated from the transfer unit housing 7 and grounded, so that the charge due to frictional charging or the like during conveyance of the recording medium is brought into contact with the grounded conveyance guide 8b to eliminate the charge. It is possible to prevent image deterioration due to sheet neutralization before transfer in a low-humidity environment and peeling discharge at the transport guide after transfer, and it is possible to improve image quality stability when the environment changes.

  In addition, the lower conveyance guide 8b is not grounded, and a power source is connected so that a voltage having a polarity opposite to the toner polarity can be applied, and the humidity is detected by a humidity sensor. By changing the applied voltage by a known control method so as to increase the value, the charge applied to the recording medium 16 from the corotron 50 or the transfer roller 9 at high humidity is transferred from the transport guide 8b via the recording medium 16. It is possible to prevent a transfer failure from occurring due to leakage.

  FIG. 4 shows an embodiment of a continuous paper printer using the transfer device of the present invention.

A charger 2, an exposure device 3, a developing device 4, and a transfer mechanism unit 6 are arranged along the peripheral surface of the photosensitive member 1 having a diameter of 262 mm. On the other hand, the recording medium 16 is conveyed to the transfer mechanism 6 by the recording medium conveying devices 17, 31, and 32, and the toner image is transferred onto the recording medium 16 by the transfer mechanism 6. The toner image on the recording medium 16 is heated to the vicinity of the transition temperature of the toner resin when passing through the pre-heater 32, and then the toner image is melted on the web 16 by a fixing device 35 including a heating roller 33 and a backup roller 34 incorporating the heater. It is fixed.
Note that double-sided printing can be performed by using two image forming apparatuses as shown in FIG.

  By using the transfer apparatus of the present invention, high-quality printing can be stably performed over a long period of time at an extremely high process speed of about 1700 mm / s.

  Although the present invention has been described above with reference to transfer from a photoconductor, the present invention can be similarly applied to transfer from an intermediate transfer belt or an intermediate transfer drum to a recording medium instead of the photoconductor.

  Therefore, by using the present invention for secondary transfer of a color electrostatic printer using an intermediate transfer system, a long-life and inexpensive color that can stably transfer with little deterioration in image quality without being affected by the paper thickness or environment. It is possible to provide a transfer device and a color continuous electrostatic recording device using the transfer device.

  1: Photoconductor, 2: Charging member, 3: Exposure device, 4: Developer, 6: Transfer mechanism, 7: Transfer housing, 9: Transfer roller, 10: Transfer roller charging means, 16: Recording medium, 17a, 17b: tractor, 50: charge applying means.

Claims (6)

Transfer means for transferring the toner image from the toner image carrier to the recording medium, a continuous recording medium, and the recording medium in contact with the recording medium at a position before the recording medium comes into contact with the toner image carrier. A conveyance guide guided between the transfer mechanism members, a transfer mechanism member having a dielectric layer on the outermost surface of the transfer means and formed in a roller shape, and a transfer mechanism member for charging the surface of the transfer mechanism member from the outside In an electrostatic recording apparatus provided with a charging means,
In a region where the recording medium is in contact with the toner image carrier on the downstream side of the conveyance guide and upstream of the transfer unit, the surface of the recording medium opposite to the surface in contact with the toner image carrier is not in contact with the recording medium. An electrostatic recording apparatus comprising: a charge applying unit configured to supply a charge having a polarity opposite to that of the toner.   The electrostatic recording apparatus according to claim 1, wherein the conveyance guide is grounded. The electrostatic recording apparatus according to claim 1, wherein a voltage having a polarity opposite to a toner polarity is applied to the conveyance guide. Transfer means for transferring the toner image from the toner image carrier to the recording medium, a continuous recording medium, and the recording medium in contact with the recording medium at a position before the recording medium comes into contact with the toner image carrier. A conveyance guide guided between the transfer mechanism members, a transfer mechanism member having a dielectric layer on the outermost surface of the transfer means and formed in a roller shape, and a transfer mechanism member for charging the surface of the transfer mechanism member from the outside In an electrostatic recording apparatus provided with a charging means,
Opposite to the surface of the recording medium that is in contact with the toner image carrier, opposite to the surface of the recording medium that is in contact with the toner image carrier, in contact with the recording medium in a non-contact manner. An electrostatic recording apparatus comprising: a transfer device provided with a charge imparting unit that supplies a charge having a polarity opposite to a toner polarity on a surface of a recording medium.   The electrostatic recording apparatus according to claim 4, wherein the conveyance guide is grounded. The electrostatic recording apparatus according to claim 4, wherein a voltage having a polarity opposite to a toner polarity is applied to the conveyance guide.

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