JP2007212684A - Image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an image forming apparatus for securing an installation space of the apparatus by a simple configuration. <P>SOLUTION: The image forming apparatus has two or more image formation parts 200 and a suction and conveying means 300 for successively sucking and conveying a transfer material S to the image formation parts 200. Each image formation part 200 is provided with an image carrier 500 for forming toner images on the surface, and a transfer means 400 for transferring the toner images on the transfer material S. The image carrier 500 is provided on the side of the transfer means 400 rather than a line section connecting a conveying means 100 so as to set the transfer material S at a transfer position contacted on a prescribed nip width during forming a conveying passage. The suction and conveying means 300 is unitized with any one adjacent transfer means 400 so as to be retreated from the transfer position by the transfer means 400 and interlock with set operation. During a maintenance, the unitized transfer means 400 and the suction and conveying means 300 are pulled to be pulled in a direction away from the image carrier 500. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an image forming apparatus used in an electrophotographic apparatus, and in particular, arranges two or more image forming units along a conveyance path, passes the transfer material through the conveyance path, and sequentially forms the transfer material. The present invention relates to an image forming apparatus for transferring a toner image.

  An image forming apparatus used in an electrophotographic apparatus, in particular, a color electronic device in which a plurality of image forming portions are arranged along a transfer material conveyance direction, and toner images formed in the image forming portion are sequentially transferred onto a transfer material. As a photographic apparatus, there exists a structure like patent document 1, 2, for example.

JP 2005-49678 A JP 2005-316192 A

  In the configuration of Patent Document 1, a toner image formed on a photoreceptor is transferred to a transfer belt such as a film and then transferred to a transfer material. In this configuration, the cross-sectional shape of the belt can be arbitrarily set by the arrangement of the tension roller, so that the degree of freedom of arrangement in the image forming apparatus can be increased.

  However, this configuration requires a certain level of belt tension in order to rotate the transfer belt. When the belt tension is low, the tension belt slips and it is difficult to obtain a stable rotation.

  If the rotation of the transfer belt is unstable, the toner image is transferred to the transfer belt in the presence of unevenness when transferring from the photoconductor to the transfer belt or when performing secondary transfer from the transfer belt to the transfer material. End up. As a result, the toner image is transferred to the transfer material so as to expand and contract in the rotation direction of the transfer belt, and there is a very high possibility that an image defect will occur.

  Further, Patent Document 2 is a configuration in which toner images are directly transferred from a photoconductor to a transfer material in sequence, but also in this configuration, since the belt has a transport function, Prone to image defects.

  Furthermore, the belts disclosed in Patent Documents 1 and 2 are applied to A4 and B5 sizes, etc., and the maximum width is relatively narrow, and the demand is high and mass production is possible, so the cost is low. It is possible to produce it with relative ease.

  On the other hand, when the belts disclosed in Patent Documents 1 and 2 are applied to a large size paper having a size larger than A3 or a wide roll paper, the maximum width is wide, and the number of users is limited so that the production is small. Difficult and expensive.

  In addition, as shown in FIG. 4 of Patent Document 2, when performing jam processing of a transfer material, the configuration in which the belt is opened and closed around one end is applied to a large-size or wide roll paper of A3 or more. Since the apparatus is increased in size and weight, workability is poor and a space for opening the belt is required.

  In particular, in the configuration as in Patent Document 2, it is difficult to uniformly press each photoconductor. As a result, when the transfer material is long, transfer unevenness occurs, or a gap is formed between the transfer material, the transfer material, and the belt, and transfer omission is likely to occur.

  In order to solve the above problems, the present invention provides an image forming apparatus in which a substantially vertical conveyance path is formed by a conveyance unit that conveys a transfer material. The conveyance path includes two or more image forming units; The image forming unit includes a suction conveyance unit disposed between the image forming units and sequentially sucking and conveying the transfer material to the image forming unit. Each image forming unit includes an image carrier on which a toner image is formed, and the toner. A transfer means for transferring the image to the transfer material, and the image carrier is set at a transfer position where the transfer material contacts with a predetermined nip width at the time of forming the transfer path, rather than a line segment connecting the transfer means. The suction conveyance means provided on the transfer means side is unitized with one of the adjacent transfer means so that the transfer means is retracted from the transfer position or interlocked with the set operation, and the transfer material is transferred to the transfer position when the conveyance path is formed. The transport hand to press with It is arranged on the image carrier side with respect to the line segment that connects them. When releasing the conveyance path, the unitized transfer unit and suction conveyance unit are pulled out of the conveyance path and pulled away from the image carrier. It is characterized by that.

  According to the second aspect of the present invention, the suction conveyance means includes a conveyance belt having a flat portion facing a surface opposite to the transfer surface of the toner image of the transfer material, and when returning the formation of the conveyance path, The flat surface portion of the suction conveyance means is set on the image carrier side with respect to a line segment connecting the contacts of each image carrier through which the transfer material passes.

  Furthermore, the invention described in claim 3 comprises: a corona house having an opening facing the surface opposite to the transfer surface of the toner image of the transfer material; and a corona wire stretched in the corona house. It is a corona transfer apparatus having. Furthermore, the invention described in claim 4 is characterized in that the opening is formed narrower than the nip width. The invention described in claim 4 is characterized in that a handling member for handling the transfer material is provided at one end of the suction conveyance means adjacent to the corona transfer device.

  With the above configuration, according to the present invention, a vertical conveyance path is formed by the conveyance means, and an image carrier on which a toner image is formed on the surface between the conveyance paths, and the toner image is transferred to a transfer material. The installation space of the apparatus can be secured by arranging two or more image forming units provided with transfer means.

  Further, by providing an image carrier on the transfer unit side with respect to the line connecting the conveyance units and uniting the suction conveyance unit with one of the adjacent transfer units, the transfer unit can be retracted or set from the transfer position. The same operation can be performed in conjunction. In addition to this, the apparatus can be configured with common parts, and the manufacturing cost can be reduced.

  Further, when forming the conveyance path, the suction conveyance unit is disposed on the image carrier side of the line connecting the conveyance units so that the transfer material has a predetermined nip width with respect to the image carrier, When canceling the formation of the conveyance path, the transfer unit is retracted from the transfer position to form a predetermined work space, and the suction conveyance unit is shifted to the opposite side where the image carrier is arranged to transfer the transfer material to the image. By arranging it so as to be in contact with or away from the carrier, a work space for performing maintenance in the apparatus is formed only by pulling out in one direction, so that the work space for performing maintenance can be saved and a predetermined transfer material can be stored. The toner images can be transferred sequentially to the position, and transfer omission can be prevented.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 schematically shows an image forming apparatus according to the present invention.

  As shown in FIG. 1, in this image forming apparatus, a transport path P is formed in a substantially vertical direction by two or more transport units 100, and two or more image formations are formed between the transport paths P at a predetermined interval. The part 200 is arranged. Under this configuration, the transfer material S is fed from a paper supply means (not shown) to the transport path P, and a toner image is sequentially transferred to the transfer material S to form a color image, and then these unfixed color images are transferred. It is to fix together.

  The transfer material S is a sheet cut out at a predetermined timing by feeding a cut paper or roll paper cut in advance to a specified size for a predetermined time.

  The transport unit 100 transports the transfer material S and includes a first transport unit 110 and a second transport unit 120. The first transport unit 110 is disposed in front of the image forming unit 200 that first transfers the toner image to the transfer material S. The second conveying unit 120 is disposed after the image forming unit 200 that finally transfers the toner image to the transfer material S.

  The first transport unit 110 includes a registration roller 111 and a counter roller 112. The registration roller 111 is made of a material having a small eccentricity, and the surface thereof is coated with a ceramic coat of about 25 μm in order to increase the friction coefficient and increase the grip force of the transfer material S.

  The counter roller 112 is configured such that a predetermined pressing force is applied to a portion passing through the center of the transfer material S. As a specific example of this configuration, although not shown in the figure, a crown shape that has a maximum diameter at the center and a diameter that decreases toward the end side, or a plurality of rollers provided on a plurality of rotatable shafts, Some have a diameter that applies a predetermined pressing force to the roller 112 and a diameter that causes the rollers on both sides to slightly float from the counter roller 112.

  With this configuration, the transfer material S that passes through the first transport unit 110 is forced to act only on the center, and therefore, the transfer material S can be transported while preventing the transfer material S from being skewed. Further, even if the transfer material S is waved before the first conveying means 110 due to the transfer amount of the transfer material S, the elongation of the transfer material S, etc., it is extended before passing through the first conveying means 110, It is possible to prevent transfer omission and toner image position shift in each image forming unit 200.

  The second transport unit 120 includes a registration roller 122 and a corona charger 122. The registration roller 122 is the same as the registration roller 111 described in the first conveying unit 110. The corona charger 122 is charged with the same polarity as the toner image transferred to the transfer material S. With this configuration, the transfer material S can be conveyed to the fixing device 600 without destroying the color image formed on the transfer material S.

  Here, the relationship between the holding force for pulling the transfer material S, that is, the grip force, is that the grip force of the registration roller 111 of the first transport unit 110> (the transfer material S is fixed to each image carrier 500 with a predetermined value). (Grip force acting when pressed so as to have a nip width NP + grip force acting when conveyed by the suction conveying means 300 disposed between the image carriers 500)> Registration roller 122 of the second conveying means 120 It has become the grip power. The predetermined nip width is determined by the outer diameter, hardness, etc. of the image carrier 200.

  The image forming unit 200 includes an image carrier 500 and a transfer unit 400. In this embodiment, the image forming unit is arranged with yellow (Y), magenta (M), cyan (C), and black (BK) in order in order to obtain a color image on the transfer material. For example, the image carrier 500 rotates in the direction indicated by an arrow, that is, counterclockwise, and has a configuration in which an electrophotosensitive member is provided on the surface of a drum-like substrate such as aluminum. As the photoconductor, a known photoconductor such as an OPC (organic photoconductor) photoconductor or an amorphous silicon photoconductor can be used.

  The image carrier 500 includes a transfer unit 400 based on a line segment in which the transfer material S connects the charged portion with the registration roller 122 of the second conveyance unit 120 from the contact portion between the registration roller 111 and the counter roller 112 of the first conveyance unit 110. Placed on the side. With this arrangement, when the transfer material S passes through the image carrier 500, it can come into contact with the image carrier 500 so as to have a predetermined nip width NP, thereby preventing transfer omission.

  Around the image carrier 500, there are an eraser 510 for erasing residual charges on the image carrier 500, a charger 520 for uniformly charging the surface of the image carrier 500 to a specific polarity, and a charged image. An exposure device 530 for forming an electrostatic latent image on the surface of the image carrier 500 by making optical information incident (image exposure) on the surface of the carrier 500, and supplying a developer to the surface of the image carrier 500 A developing device 700 for developing the latent image to form a developer image, and a transfer unit 400 for transferring the developer image formed on the image carrier 500 onto the transfer material S are arranged.

  Here, the developing device 700 includes a developing container 710 that contains a developer made of non-magnetic one-component toner, an agitating unit 720 that agitates the developer in the developing container 710, and at least a surface layer having conductivity. A developer carrier 730 formed of an elastic roller, and a layer thickness regulating means 740 that is disposed in contact with the developer carrier 730 at an appropriate pressure and forms a thin layer of a constant developer on the developer carrier 730; And a developer supply means 750 for supplying the developer in the developer container 710 to the developer carrier 730.

  These are connected to an appropriate bias power source, and a predetermined bias voltage (bias) is applied to each of them. As the developer, for example, a developer having the same polarity as the charged polarity of the image carrier 500 is used for reversal development.

  The agitation unit 720 is provided behind the developer supply unit 750 and is not shown, but has a central axis extending in the same direction as the axis of the developer carrier 730 and agitation provided at a plurality of locations in the axial direction of the central axis. With wings. The developer carrier 730 has a configuration in which, for example, an elastic intermediate layer 731 is formed around a central axis made of a conductive rigid body such as stainless steel, and an elastic surface layer is formed on the outer periphery of the intermediate layer. Rotate to.

  The layer thickness regulation unit 740 regulates the layer thickness of the developer supplied in a layer form on the developer carrier 730 by the developer supply unit 750. The layer thickness regulating means 740 is composed of a conductive or semiconductive rotatable roller body, and is connected to a power source (not shown) for applying a predetermined voltage. Further, the layer thickness regulating means 740 is disposed upstream of the contact portion between the developer carrier 730 and the image carrier 500 when viewed from the rotation direction of the developer carrier 730.

  The developer supply means 750 is composed of a brush roller in which a large number of hairs made of conductive fibers such as conductive nylon or rayon in which carbon fine powder is mixed around the core metal are implanted substantially uniformly. . The brush roller is disposed so as to extend in parallel with the axis of the developer carrier 730 with a predetermined distance from the developer carrier 730. The central axis of the developer supply means 750 is connected to an appropriate power source.

The brush roller rotates in the direction of the arrow while contacting the developer carrier 730 with a predetermined pressure to supply the developer in the developer container 710 to the developer carrier 730, and at the same time, the developer carrier 730 is frictionally charged. Charge the toner on top. The brush roller is arranged so that the tip of the brush contacts the developer carrier 730 with appropriate elasticity (pressure due to the stiffness of the fibers). Although not limited, it is preferable that the bristle of the brush is 3 to 6 mm, the fiber thickness is about (denier D / filament F), and the fiber density is 10,000 to 25,000 / inch ² .

  As described above, in the embodiment of the present invention, the developer supply means 750 is a fur brush, but it may be a foam of urethane rubber mixed with carbon fine powder.

  The transfer unit 400 includes a corona transfer device 410 and a peeling device 450. The peeling device 450 is adjacent to the corona transfer device 410. The corona transfer device 410 includes a corona wire 440 and a corona house 430 that covers the corona wire 440. An appropriate number of corona wires 440 are stretched inside the corona house 430, one in the example of FIGS. 1 and 2, and the corona wires 440 and the corona house 430 extend in the axial direction of the image carrier 500. The corona discharge of the corona wire 440 is discharged from the opening 420 of the corona housing to the discharge transfer region.

  The corona house 430 includes a bottom portion and a pair of two side plates, and is disposed to face the image carrier 500. A portion of the housing facing the image carrier 500 has an opening 420. As shown in FIG. 2, the corona housing opening 420 is provided with a bent portion 450 at the upper end of the side plate on the side facing the next image forming portion 200 from the image forming portion 200 to transfer the toner image on the image carrier 500. The nip width NP transferred to the material S is narrower. With this configuration, a range in which the transfer material S is charged is an opening 420. As a result, no charge is applied to the portion where the transfer material S is not in contact with the image carrier 500, and the toner moves into the air, thereby preventing image scattering.

  The suction conveyance unit 300 includes a conveyance belt 320 provided with a plurality of intake holes (not shown) and a roller that supports the conveyance belt 320. The transfer material S to which the toner image is first transferred is transferred to the next image forming unit 200. And is provided between the image forming units 200. The conveyance belt 320 includes a flat portion 310 facing the surface opposite to the transfer surface of the toner image of the transfer material S, and is unitized with the transfer unit 400. A handling member 470 for handling a transfer material is provided at one end of the suction conveyance unit 300 adjacent to the corona transfer device 410.

  Further, when forming a color image on the transfer material S, the flat surface portion 310 is moved from the contact portion between the registration roller 111 of the first transport unit 110 and the counter roller 112 by the registration roller 122 of the second transport unit 120. It is set on the image carrier 500 side from the line segment connecting the charged portions.

  With this configuration, the nip width NP of the transfer material S when passing between the first transport unit 110 and the suction transport unit 300 and between the suction transport unit 300 and the suction transport unit 300 and the second transport unit 120 is kept constant. Transfer deviation can be prevented. Further, the transfer material S is handled by the handling member 470 before moving to the image carrier 500 other than the first image carrier 500. During this time, the transfer material S is conveyed while being sucked by the suction conveying means 300. As a result, the transfer material S can be conveyed to the image carrier 500 in a state where the wave is eliminated.

  In addition, a spraying means 800 is provided above the peeling device 450. The spray unit 800 is disposed so as to blow wind from the image carrier 500 to the vicinity of the leading end of the suction unit and from the image carrier 500 to the vicinity of the introduction side of the second transport unit 120.

  With this configuration, after the toner image is transferred, the wind passes between the image carrier 500 and the transfer material S sucked and adsorbed to the image carrier 500, and the transfer material S is reliably separated from the image carrier 500. can do. At this time, the action of the peeling device 450 also contributes.

  With the above configuration, when a color image is formed on the transfer material S, first, in the state where the first image carrier 500 is rotating in the direction of the arrow, the residual potential remaining on the image carrier 500 is erased. The surface of the image carrier 500 is uniformly charged by the charger 520. The electrostatic latent image is conveyed to a position (development section) in contact with the developer carrier 730 by the rotation of the first image carrier 500.

  On the other hand, in the developing device 700, in synchronization with the rotation of the image carrier 500, the developer carrier 730 and the developer supply means 750 are rotated in the directions indicated by the respective arrows by drive sources (not shown), and the developer carrier is supported. A predetermined bias voltage is applied to each of the body 730, the developer supply unit 750, and the layer thickness regulating unit 740.

  The developer in the developer container 710 is agitated by the rotation of the agitation means 720 and the developer supply means 750 and is supplied to the developer supply means 750 and then to the developer carrier 730, and the developer layer is formed on the developer carrier 730. Is formed. The developer layer is regulated by the layer thickness regulating means 740 so as to be a uniform thin layer of 1 to 3, and then is carried to the development section as the developer carrier 730 rotates.

  The thinned developer is supplied to the electrostatic latent image on the image carrier 500 in the development section, and development is performed by suction and adsorption.

  The developer image formed on the first image carrier 500 is conveyed to the transfer region (nip width NP) by the rotation of the image carrier 500. Here, by the action of the corona transfer device 410, an electric field having a polarity opposite to the polarity of the developer is applied from the back side of the transfer material S, and the toner image is transferred onto the transfer material S.

  The toner images transferred by the first image forming unit 200 are sequentially transferred by the second image forming unit 200, the third image forming unit 200, and the fourth image forming unit 200, and the color image is transferred onto the transfer material S. An image is formed. Thereafter, the transfer material S on which the color image is formed is conveyed to the fixing device 600 and fixed.

   On the other hand, the developer remaining on the image carrier 500 that is not transferred to the transfer material S is exposed to the entire surface by the eraser 510 and becomes substantially the same potential as the dark portion potential (image background portion potential) of the image carrier 500.

  Next, charging and exposure for the same image formation as described above are performed, and the toner is again conveyed to the developer carrier 730. The developer carrier 730 collects the developer remaining on the image carrier 500 to the developing device 700 and supplies a new developer to the surface of the image carrier 500 to generate the next electrostatic latent image. develop.

   Next, when maintenance is performed in the transport path P, the suction transport unit 300 is pulled out to the opposite side (in the direction of the arrow) where the image carrier 500 is disposed to cancel the formation of the transport path P. As a result, the suction transfer means 300 and the unitized transfer means 400 are retracted from the transfer position of the transfer material S to form a predetermined work space.

  At the same time, the suction conveyance means 300 is also shifted in the direction of the arrow, and when the transfer material S is in the conveyance path P, the first conveyance means 110, the suction conveyance means 300, the suction conveyance means 300, and the suction The tension is released between the transport unit 300 and the second transport unit 120, and the transfer material S is brought into contact with or separated from the front image carrier 500 (in a state where the transfer material S is in contact with the surface of the image carrier 500).

  As described above, when the conveyance path P is formed in the suction conveyance unit 300, the image is more than the line segment connecting the conveyance units so that the transfer material S has a predetermined nip width NP with respect to the image carrier 500. When it is arranged on the side of the carrier 500 and further the formation of the conveyance path P is cancelled, the transfer means 400 is retracted from the transfer position to form a predetermined work space, and the suction conveyance means 300 is moved by the image carrier 500. By shifting the transfer material S so as to contact or separate from the image carrier 500 by shifting to the opposite side, the work space for performing maintenance in the apparatus is formed only by pulling out in one direction. Can be saved, and the toner images can be sequentially transferred to a predetermined position of the transfer material S, thereby preventing transfer omission.

1 is a schematic diagram of an image forming apparatus of the present invention. FIG. 3 is an enlarged view of an image forming unit of the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Conveying means 200 Image forming part 300 Suction conveying means 310 Flat part 320 Conveying belt 400 Transfer means 410 Corona transfer device 420 Opening 430 Corona house 440 Corona wire 500 Image carrier NP Nip width S Transfer material P Conveyance path

Claims (4)

In an image forming apparatus in which a substantially vertical conveyance path is formed by a conveyance unit that conveys a transfer material,
The transport path includes two or more image forming units, and a suction transport unit that is disposed between the image forming units and sequentially sucks and transports the transfer material to the image forming unit.
Each of the image forming units includes an image carrier on which a toner image is formed on a surface, and a transfer unit that transfers the toner image to the transfer material.
The image carrier is provided closer to the transfer means than a line connecting the transport means so that the transfer material is set at a transfer position where the transfer material contacts with a predetermined nip width when the transport path is formed.
The suction conveyance means is unitized with one of the adjacent transfer means so that the transfer means is retracted from the transfer position or interlocked with the set operation, and the transfer material is moved to the transfer position when the conveyance path is formed. It is arranged on the image carrier side with respect to a line segment connecting the conveying means so as to press,
2. An image forming apparatus according to claim 1, wherein when releasing the transport path formation, the transfer unit and the suction transport unit that are unitized are pulled out from the transport path in a direction away from the image carrier. The suction conveyance means comprises a conveyance belt having a flat portion facing the surface opposite to the transfer surface of the toner image of the transfer material,
The flat surface portion of the suction conveyance means is set on the image carrier side with respect to a line segment connecting the contact points of the image carriers through which the transfer material passes when forming the conveyance path. The image forming apparatus according to 1. The transfer means includes a corona transfer device having a corona house having an opening facing a surface opposite to a transfer surface of the toner image of the transfer material, and a corona wire stretched in the corona house,
The image forming apparatus according to claim 1, wherein the opening is formed narrower than the nip width.   The image forming apparatus according to claim 3, wherein a handling member that handles the transfer material is provided at one end of the suction conveyance unit adjacent to the corona transfer device.