JP2013156365A - Image forming apparatus and guiding device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an image forming apparatus and a guiding device in which deterioration in image quality due to the influence of light for fixation is suppressed.SOLUTION: There is provided an image forming apparatus S which comprises: a toner image forming device 2 for forming a toner image on a photoreceptor 21; a conveyance device for conveying continuous paper P; a transfer device for transferring the toner image on the photoreceptor 21 to continuous paper in a transfer position T2; a fixing device 9A which is disposed on the downstream side in the conveyance direction of the continuous paper P from the transfer position T2 and irradiates light to the toner image transferred on the continuous paper to fix the toner image; and an upstream side device 7 which is disposed at a position having a released space capable of viewing the transfer position on the upstream side in the conveyance direction of the continuous paper from the transfer position T2 and acts on the continuous paper, wherein the upstream side device 7 has a shielding member 77 for shielding light emitted by the fixing device 9A on a side facing the transfer position.

Description

  The present invention relates to an image forming apparatus and a guide device.

  Patent Document 1 discloses a recording apparatus that records an image on paper in a copying machine. This recording apparatus first exposes a photosensitive member by an exposure device to form a latent image, then develops the latent image with toner by a developing device to form a toner image, and then transfers the toner image to a sheet, By further fixing, an image is formed on the paper.

JP-A-01-273090

  When fixing the toner image transferred to the paper to the paper, it is conceivable that the toner image is irradiated with light and the toner image is fixed by the heat of light. When the toner image is received, the toner image on the photoconductor is affected before transfer to the paper, and the image quality may deteriorate.

  SUMMARY OF THE INVENTION An object of the present invention is to provide an image forming apparatus and a guide apparatus in which deterioration of the image quality of a toner image before transfer on a photoreceptor due to the influence of fixing light is suppressed.

An image forming apparatus according to claim 1 is provided.
A toner image forming apparatus that includes a photosensitive member that is charged and exposed to form an electrostatic latent image, and that forms an electrostatic latent image on the photosensitive member and develops the toner image with toner;
A transport device that transports continuous paper along a transport path that passes through a transfer position that receives the transfer of the toner image on the photoreceptor;
A transfer device for transferring the toner image on the photoconductor onto the continuous paper at the transfer position;
The toner image is disposed on the downstream side of the transport path in the transport direction of the continuous paper from the transfer position. The toner image transferred onto the continuous paper is irradiated with light, and the toner image is applied onto the continuous paper by the heat of the light. A fixing device for fixing;
An upstream device that is disposed upstream of the transfer position in the transport direction of the continuous paper with respect to the transport position and has a released space that allows the transfer position to be viewed; Have
The upstream device includes a shielding member that shields light emitted from the fixing device on a side facing the transfer position.

  The image forming apparatus according to claim 2 is characterized in that the upstream device is a guide device provided with a guide roll for guiding the continuous sheet while rotating in contact with the continuous sheet conveyed on the conveyance path. To do.

  The image forming apparatus according to claim 3, wherein the light shielding member is closer to the conveyance path than a plane including the rotation center axis of the guide roll and the transfer position from the position away from the conveyance path toward the conveyance path. It is characterized in that it has a shape that protrudes and spreads out, and at least a region that protrudes from the plane toward the conveyance path is formed of a light shielding material.

A guide device according to claim 4 is:
A toner image forming apparatus that includes a photosensitive member that is charged and exposed to form an electrostatic latent image, and that forms an electrostatic latent image on the photosensitive member and develops it with toner, and continuous paper. And a transfer device for transferring the toner image on the photoconductor onto the continuous paper at the transfer position, and a transfer device for transferring the toner image on the photoconductor on the continuous paper at the transfer position. The toner image is disposed on the downstream side of the transport path in the transport direction of the continuous paper with respect to the transfer position, and the toner image transferred onto the continuous paper is irradiated with light so that the toner image is heated with the light. An image forming apparatus having a fixing device for fixing on paper is disposed at a position having a released space on the upstream side in the transport direction of the continuous paper with respect to the transfer position from the transfer position so that the transfer position can be viewed. Continuously transported on the lever transport path A guide device for guiding the,
A guide roll for guiding the continuous paper while rotating in contact with the continuous paper;
And a shielding member that is arranged on the transfer position side of the guide roll and shields light emitted from the fixing device.

  In the image forming apparatus according to the first aspect, the deterioration of the image quality due to the influence of the fixing light is suppressed as compared with the case where the upstream apparatus does not have the shielding member.

  The image forming apparatus according to the second aspect further suppresses intrusion of the fixing light as compared with the case where this configuration is not provided.

  In the image forming apparatus according to the third aspect, the influence of the fixing light is suppressed as compared with the case where the light blocking member does not reach the plane including the rotation center axis of the guide roll and the transfer position.

  According to the fourth aspect of the present invention, the influence of the fixing light on the photosensitive member can be suppressed as compared with the case where the shielding device is not provided.

1 is a schematic configuration diagram of an image forming apparatus which is an embodiment of an image forming apparatus of the present invention. FIG. 2 is an enlarged view of portions of a second toner image forming apparatus and a first fixing device of the image forming apparatus shown in FIG. 1. It is a perspective view which shows the external appearance of the 2nd guide apparatus shown in FIG. It is sectional drawing which shows the cross section of the 2nd guide apparatus shown in FIG. 7 is a plan view showing a light shielding member 77. FIG. It is a graph which shows the measurement result of surface potential. It is a top view which shows the light-shielding member in a modification.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic configuration diagram of an image forming apparatus which is an embodiment of the image forming apparatus of the present invention.

  The image forming apparatus S shown in FIG. 1 transports a continuous paper P that is longer than the transport path R in the longitudinal direction of the continuous paper P, and forms an image on the continuous paper P. It is. The image forming apparatus S of the present embodiment forms images on both the front and back sides of the continuous paper P in one apparatus. The image forming apparatus S includes a first toner image forming apparatus 1, a second toner image forming apparatus 2, a first transfer apparatus 3, a second transfer apparatus 4, a sheet conveying apparatus 5, a first guide apparatus 6, and a second guide. A device 7, a third guide device 8, a first fixing device 9A, a second fixing device 9B, a paper storage device IN, and a paper stacking device OUT are provided. The image forming apparatus S is also provided with a control unit C, a signal input / output unit IF, and a power supply unit E.

  The first toner image forming apparatus 1 is disposed at a position on the back surface side of the continuous paper P in the transport path R, and forms a toner image of an image formed on the back surface of the continuous paper P. The second toner image forming apparatus 2 is disposed at a position on the front side of the continuous paper P, and forms a toner image of an image formed on the front surface of the continuous paper P. The first toner image forming apparatus 1 and the second toner image forming apparatus 2 have the same configuration, and the first transfer device 3 and the second transfer device 4 have the same configuration. Therefore, the first toner image forming apparatus 1 and the first transfer apparatus 3 will be representatively described.

  The first toner image forming apparatus 1 includes a photosensitive drum 11, a charging device 12, an exposure device 13, a developing device 14, and a cleaning device 15. The photosensitive drum 11 has a cylindrical peripheral surface, and rotates in the direction of an arrow A1 around the axis of the cylinder. The photosensitive drum 11 has a configuration in which an undercoat layer, a charge generation layer, and a charge transport layer are sequentially laminated on a cylindrical substrate peripheral surface (not shown). When the photosensitive drum 11 is irradiated with light with the peripheral surface charged, an electrostatic latent image is formed by reducing the amount of charge in the portion irradiated with the light.

  The charging device 12, the exposure device 13, and the developing device 24 are disposed around the photosensitive drum 11 in the order of the rotation direction A1. The charging device 12 charges the peripheral surface of the photosensitive drum 11. The charging device 12 charges the photosensitive drum 11 in a non-contact manner using corona discharge. However, as the charging device, for example, a charging roll that performs charging in contact with the photosensitive drum 11 may be employed. The exposure device 13 irradiates the photosensitive drum 11 with exposure light based on an image signal supplied from the outside of the image forming apparatus S via the signal input / output unit IF. An electrostatic latent image is formed by irradiating light onto the peripheral surface of the charged photosensitive drum 11. The exposure device 13 is configured by an LED array in which a plurality of light emitting diodes (LEDs) are arranged side by side in the width direction intersecting the moving direction of the circumferential surface of the photosensitive drum 11. However, as the exposure apparatus, for example, a configuration in which laser light emitted from a laser emitter is reflected by a rotary polygon mirror and scanned in the width direction of the photosensitive drum 11 can be employed. The developing device 14 develops the electrostatic latent image on the circumferential surface of the photosensitive drum 11 with toner, thereby forming a toner image on the circumferential surface of the photosensitive drum 11. The developing device 14 contains a two-component developer in which toner and a magnetic carrier are mixed. The developing device 14 agitates the developer to charge the toner, and develops the electrostatic latent image on the peripheral surface of the photosensitive drum 11 with the charged toner. As the toner adheres, an electrostatic latent image is formed on the peripheral surface of the photosensitive drum 11. The cleaning device 15 cleans the photosensitive drum 11 by removing unnecessary substances such as toner remaining on the circumferential surface of the photosensitive drum 11 after the toner is transferred to the continuous paper P by the first transfer device 3 described later. To do.

  The first transfer device 3 transfers the toner image on the photosensitive drum 11 to the back surface of the continuous paper P. The first transfer device 3 is disposed on the opposite side of the photosensitive drum 11 with the continuous paper P interposed therebetween. More specifically, the first transfer device 3 faces a position on the peripheral surface of the photosensitive drum 11 downstream of the developing device 24 in the rotation direction A1. The continuous paper P is in contact with the photosensitive drum 11 at a transfer position T1 between the first transfer device 3 and the photosensitive drum 11. The first transfer device 3 is a device that charges the continuous paper P in a non-contact manner using corona discharge. However, as the transfer device, for example, a transfer roll to which a voltage is applied that rotates while contacting the continuous paper P may be employed. The first transfer device 3 causes toner to adhere to the continuous paper P due to the electric field generated between the continuous paper P and the photosensitive drum 11, and the toner image on the photosensitive drum 11 is transferred to the back surface of the continuous paper P. The The second transfer device 4 provided corresponding to the surface has the same configuration as the first transfer device 3, and transfers the toner image on the photosensitive drum 21 onto the surface of the continuous paper P.

  The paper transport device 5 transports the continuous paper P stored in the paper storage device IN in the transport direction indicated by the arrow D along the transport path R. The paper transport device 5 includes a belt-like pin feed tractor 51 that engages with a feed hole provided in the continuous paper P and transports the continuous paper P, a back tension roll 52 for applying tension to the continuous paper P, and , Cylindrical conveyance rolls 54 to 58 for conveying the continuous paper P are provided. In the image forming apparatus S of the present embodiment, the second toner image forming apparatus 2 is disposed above the first toner image forming apparatus 1 and is disposed above the second toner image forming apparatus 2. A second fixing device 9B is arranged. Correspondingly, the conveyance path R extends substantially in the vertical direction after passing through the pin feed tractor 52. While the continuous paper P is conveyed from the bottom to the top, the continuous paper P passes through the transfer position T1 between the photosensitive drum 11 of the first toner image forming apparatus 1 and the first transfer device 3, and the second toner. It passes through the transfer position T2 between the photosensitive drum 21 of the image forming apparatus 2 and the second transfer device 4, and further passes through the first fixing device 9A. The conveyance path R reaches the paper stacking device OUT after passing through the second fixing device 9B.

  The first guide device 6 is disposed on the upstream side in the transport direction D from the transfer position T1 between the photosensitive drum 11 of the first toner image forming device 1 and the first transfer device 3. The first guide device 6 is a device that acts on the continuous paper P. More specifically, the first guide device 6 is a device that guides the continuous paper P toward the photosensitive drum 11 and increases the area in contact with the photosensitive drum 11. is there. Further, the second guide device 7 is disposed upstream of the transfer position T2 between the photosensitive drum 21 of the second toner image forming device 2 and the second transfer device 3 in the transport direction D. Similar to the first guide device 6, the second guide device 7 guides the continuous paper P toward the photoconductor drum 21 and increases the area of contact with the photoconductor drum 21. The third guide device 8 is disposed between the transfer position T2 and the first fixing device 9A, and guides the continuous paper P toward the fixing device 9A.

  The first fixing device 9A and the second fixing device 9B are devices that fix the toner image transferred onto the continuous paper P onto the continuous paper P. The first fixing device 9 </ b> A is disposed downstream of the transfer position D between the transfer position between the photosensitive drum 11 and the first transfer device 3 and the transfer position between the photosensitive drum 21 and the second transfer device 4. Has been. The first fixing device 9 </ b> A is arranged above the second transfer device 4. The second fixing device 9B is disposed further downstream in the transport direction D than the first fixing device 9A. The first fixing device 9A faces the back surface of the continuous paper P, and fixes the toner image on the back surface of the continuous paper P. The second fixing device 9B faces the surface of the continuous paper P and fixes the toner image on the surface of the continuous paper P. The first fixing device 9 </ b> A and the second fixing device 9 </ b> B are provided with flash lamps 81 </ b> A and 91 </ b> B that emit flash light (flash light) on the continuous paper P at positions facing the continuous paper P. The first fixing device 9A and the second fixing device 9B periodically irradiate the continuous paper P on which the toner image is formed with flash light, and melt the toner by the heat of the flash light to thereby melt the toner on the continuous paper P. The image is fixed on the continuous paper P.

  The paper stacking device OUT stacks and stores paper on which an image is formed. The paper stacking apparatus OUT is provided with a swing guide SG that swings in the direction of arrow F with the upper end as a fulcrum. The continuous paper P discharged through the swing guide 91B is guided by the swing guide 91B and stacked and accommodated in the paper stacking apparatus OUT while being alternately folded at the perforations at the page boundaries.

  In the image forming apparatus S configured as described above, the continuous paper P stored in the paper storage device IN is pulled out by the pin feed tractor 51 of the paper transport device 5 and transported along the transport path R. The continuous paper P passes through the transfer position between the photosensitive drum 11 of the first toner image forming apparatus 1 and the first transfer device 3 while being conveyed upward along the conveyance path R, and thereafter It passes through a transfer position between the photosensitive drum 21 of the second toner image forming apparatus 2 and the second transfer device 4.

  On the other hand, in the first toner image forming apparatus 1, the peripheral surface of the photosensitive drum 11 is charged by the charging device 12, light is irradiated by the exposure device 13, and an electrostatic latent image is formed. The electrostatic latent image is developed to form a toner image. The back surface of the continuous paper P is in contact with the photosensitive drum 11, and the toner image is transferred from the photosensitive drum 11 by the first transfer device 3. Also in the second toner image forming apparatus 2, a toner image is formed on the peripheral surface of the photosensitive drum 21 by the charging device 22, the exposure device 23, and the developing device 24. The surface of the continuous paper P is in contact with the photosensitive drum 21, and the toner image is transferred from the photosensitive drum 21 by the second transfer device 4.

  The continuous paper P with the toner images transferred on both the front and back surfaces is first fixed on the back surface by the first fixing device 9A, and then fixed on the front surface by the second fixing device 9B. The continuous paper P on which the toner images are fixed on both the front and back sides is stacked and accommodated in the paper stacking apparatus OUT.

  FIG. 2 is an enlarged view of the second toner image forming device 2 and the first fixing device 9A of the image forming device S shown in FIG.

  In FIG. 2, the second guide device 7, the second transfer device 4, the third guide device 8, the first fixing device 9 </ b> A, and the transport roll 54 are transported along the transport path R along which the continuous paper P is transported. A state of arrangement in the order of D is shown. FIG. 2 also shows a cleaning device 15, a charging device 12, and a developing device 14 that are disposed around the photosensitive drum 21 that is disposed on the opposite side of the second transfer device 4 with the continuous paper P interposed therebetween. Has been.

  Here, the second toner image forming apparatus 2 corresponds to an example of a toner image forming apparatus according to the present invention, and the second transfer apparatus 4 corresponds to an example of a transfer apparatus according to the present invention. The second guide device 7 corresponds to an example of an upstream device according to the present invention, and also corresponds to an example of a guide device according to the present invention.

  The second transfer device 4 is a unit that is detachable in a direction away from the photosensitive drum 21 in order to remove paper and replace parts when a paper jam occurs. The second transfer device 4 includes a corona discharge device 41 that faces the photosensitive drum 21. The continuous paper P is in contact with the transfer position T <b> 2 facing the corona discharger 41 of the photosensitive drum 21.

  The second guide device 7 is disposed at a position having an open space where the transfer position T2 can be viewed, which is upstream of the transfer position T2 in the transport direction D. More specifically, the second guide device 7 is disposed immediately below the transfer position T2, that is, at a position immediately upstream in the transport direction D with respect to the transfer position T2, and the second guide device 7 is located between the transfer position T2 and the transfer position T2. Nothing other than the continuous paper P is disposed between them. The second guide device 7 includes a guide roll 71 that guides the continuous paper P. The guide roll 71 is arranged at a position protruding from the photosensitive drum 21 toward the photosensitive drum 21 with respect to the tangential plane at the position facing the second transfer device 4. Therefore, the conveyance path R of the continuous paper P is bent toward the photosensitive drum 21, and the contact area between the continuous paper P and the photosensitive drum 21 is increased as compared with the case where no guide roll is present. The guide roll 71 of the second guide device 7 contacts the back surface of the continuous paper P onto which the toner image has been transferred by the first toner image forming device 1. The guide roll 71 is in contact with the entire width of the continuous paper P. The guide roll 71 is rotationally driven at a peripheral surface speed that matches the conveyance speed of the continuous paper P so that the toner roll already transferred onto the back surface of the continuous paper P does not rub. The guide roll 71 is made of a material that suppresses adhesion of toner on the continuous paper P, and is applied with a potential that reduces the amount of adhesion. The second guide device 7 is also provided with a brush-type cleaner 72 and a blade-type cleaner 73 for removing toner that has adhered to the guide roll 71.

  The third guide device 8 includes a guide roll 81 that guides the continuous paper P. The guide roll 81 of the third guide device 8 is in contact with the surface of the continuous paper P onto which the toner image has been transferred by the second toner image forming device 2. The third guide device 8 bends the path of the continuous paper P so that the continuous paper P approaches the first fixing device 9A. The third guide device 8 has the same configuration as the second guide device 7, and also includes a brush-type cleaner 82 and a blade-type cleaner 83 for removing toner adhering to the guide roll 81. .

  Further, on the opposite side of the third guide device 8 across the transport path R of the continuous paper P, when a new continuous paper P is stored in the paper storage device IN, the leading end portion of the continuous paper P is transported. The conveyor 59 is arranged. The transporter 59 is provided with a transport roll 591 that sandwiches the continuous paper P between the transport roll 59 and the guide roll 81. The transport roll 591 is retracted from the transport path R when an image is formed on the continuous paper P.

  The first fixing device 9A is disposed on the transport path R on the downstream side in the transport direction D of the continuous paper P from the transfer position T2 of the second toner image forming apparatus 2. Between the second toner image forming device 2 and the first fixing device 9A, a light shielding member L is disposed in addition to the third guide device 8 and the transport device 59. The light shielding member L is provided with a long hole H through which the continuous paper P passes. The continuous paper P passes through the long hole H of the light shielding member L and is conveyed to the first fixing device 9A. Since a part of the light from the first fixing device 9A is blocked by the light shielding member L, the amount of light reaching the photosensitive drum 21 from the first fixing device 9A is reduced. Further, the amount of light reaching the photosensitive drum 21 from the first fixing device 9 </ b> A is also reduced by bending the path of the continuous paper P by the third guide device 8.

  However, the long hole H of the light blocking member L has a size that avoids contact with the continuous paper P before the fixing process, and a part of the light from the first fixing device 9A has the long hole H. pass. Further, part of the light can also pass through the continuous paper P itself. Further, a part of the light from the first fixing device 9A spreads through a gap around the light shielding member L and the like. In this way, a part of the light emitted from the first fixing device 9 </ b> A is arranged with the light-shielding member L, the third guide device 8, and the photosensitive drum 21 upstream in the transport direction D from the transport device 59. It reaches the second toner image forming apparatus 2.

  Of the peripheral surface of the photosensitive drum 21, the portion downstream in the transport direction D, that is, the portion facing the first fixing device 9 </ b> A is a portion from passing through the transfer position T <b> 2 until being charged by the charging device 22. For this reason, even if light other than the exposure device 23 is irradiated to the region from the transfer position T2 to the charged position, the influence on the toner image is relatively small.

  On the other hand, when light other than the exposure device 23 is irradiated to a region upstream of the transfer position T2 in the peripheral surface movement direction (arrow A2) in the peripheral surface of the photoconductor drum 21, the photoconductor drum The influence on the toner image is relatively large because the potential on the 21 circumferential surface is changed. For example, if the light from the first fixing device 9 </ b> A is reflected by the guide roll 71 of the second guide device 7 to illuminate the portion holding the toner image on the circumferential surface of the photosensitive drum 21, The potential drops. Since the toner of the toner image is held by the potential on the circumferential surface of the photosensitive drum 21, the image of the illuminated portion is blurred. Since the first fixing device 9A in the present embodiment periodically emits flash light, the effect of the flash light is periodically generated on the photosensitive drum 21 and appears in a stripe shape in the toner image.

  The second guide device 7 of this embodiment is provided with a member that blocks light from being reflected by the guide roll 71 and irradiating the photosensitive drum 21.

  FIG. 3 is a perspective view showing an appearance of the second guide device shown in FIG. FIG. 4 is a cross-sectional view showing a cross section of the second guide device shown in FIG.

  The second guide device 7 includes a brush cleaning piece 74, a toner conveying member 75, a casing 76, and a light shielding member 77 in addition to the above-described guide roll 71, brush type cleaner 72, and blade type cleaner 73. Yes.

  The guide roll 71 is a cylindrical member that extends over the entire width of the continuous paper P, and contacts the back surface of the continuous paper P to guide the continuous paper P. The guide roll 71 is rotationally driven in the direction of arrow G in accordance with the conveyance speed of the continuous paper P. The guide roll 71 has a peripheral surface formed of a white fluororesin-based resin material so as to suppress adhesion of toner transferred to the back surface of the continuous paper P. The guide roll 71 is also provided with a potential for suppressing toner adhesion. As described above, the guide roll 71 is disposed at a position protruding from the photosensitive drum 21 toward the photosensitive drum 21 with respect to the tangential plane of the photosensitive drum 21 at a position facing the second transfer device 4. The conveyance path R of P is bent. As a result, in the transport direction D of the continuous paper P (see FIG. 2), the light that travels from the upstream side of the second guide device 7 is prevented from being irradiated onto the photosensitive member 21.

  The brush-type cleaner 72 contacts the guide roll 71 to remove toner and unnecessary materials attached to the guide roll 71. The brush cleaning piece 74 is brought into contact with the brush type cleaner 72 to scrape off unnecessary substances such as toner attached to the brush type cleaner 72. Further, the blade-type cleaner 73 scrapes off unnecessary substances attached to the guide roll 71 by applying a blade provided at the tip to the guide roll 71. The blade type cleaner 73 is rotatably provided between a posture in contact with the guide roll 71 and a posture away from the guide roll 71. The toner conveying member 75 is a member provided with a spiral blade, and rotates to discharge the scraped unnecessary material to the outside of the second guide device 7. The casing 76 is a container that holds a guide roll 71, a brush-type cleaner 72, a blade-type cleaner 73, a brush cleaning piece 74, and a toner conveying member 75. In addition, the casing 76 is also provided with a closing member 78 that closes a gap between the guide roll 71 and the casing 76 in order to prevent unnecessary objects removed from the guide roll 71 from leaking to the outside.

  The light shielding member 77 is a member disposed on the side of the second guide device 7 facing the transfer position T2, that is, on the downstream side of the guide roll 71 in the transport direction D of the continuous paper P. The light shielding member 77 is fixed to the casing 76 and protrudes from the position away from the transport path R toward the transport path R on the guide roll 71. More specifically, the light shielding member 77 has a shape that protrudes and spreads to the transport path R side from the plane J including the rotation center axis 71a of the guide roll 71 and the transfer position T2. The light shielding member 77 extends to a position where contact with the continuous paper P is avoided.

  FIG. 5 is a plan view showing the light shielding member 77. FIG. 5 shows a state in which the edge of the light shielding member 77 facing the conveyance path R is directed downward.

  The light shielding member 77 shown in FIGS. 3 to 5 is a plate-like member. More specifically, the light shielding member 77 has a structure in which a light shielding film is attached to the surface of a resin base material. The light-shielding film has light-shielding characteristics such that the influence on the toner image on the photosensitive drum 21 is not visually recognized at the wavelength of the light emitted by the first fixing device 9A. For example, the light transmittance of the light shielding film is about 0.5% or less at 800 nm which is the main wavelength of light emitted from the fixing device 9A. The light shielding film is formed of a material having a lower reflectance than the material of the peripheral surface of the guide roll 71. The light shielding film is made of a black resin material. Therefore, the reflection by the light shielding member 77 itself is reduced as compared with the case of other colors.

  In the second guide device 7 shown in FIGS. 3 and 4, a light shielding member 77 is arranged on the side of the second guide device 7 facing the transfer position T2. The light blocking member 77 blocks light emitted from the first fixing device 9A. For this reason, compared with the case where the light-shielding member is not disposed, the light reaching the two guide device 7 is reflected by the guide roll 71 and the amount of light that illuminates the photosensitive drum 21 is reduced. Therefore, a decrease in the potential of the photosensitive drum 21 due to the light of the first fixing device 9A is suppressed, and deterioration in image quality such as blurring of the toner image is suppressed.

  Further, the light shielding member 77 has a shape that protrudes and spreads to the transport path R side from the plane J including the rotation center axis 71a of the guide roll 71 and the transfer position T2. Accordingly, for example, as compared with the case of a shape spreading only in front of the plane J, light reflection by the portion of the guide roll 71 facing the transfer position T2 is suppressed, and the influence on the deterioration of the toner image is suppressed.

[Measurement example]
Here, in the above-described configuration, the surface potential of the peripheral surface of the photosensitive drum when the first fixing device emits light was measured. In this measurement, the peripheral surface of the photosensitive drum 21 is charged by the charging device 22, and the peripheral surface of the photosensitive drum when the first fixing device emits light in a state where the exposure by the exposure device 23 is stopped, particularly, the transfer. The surface potential near position T2 was measured. Further, as a comparative example, the surface potential was measured even in a configuration in which the light shielding member 77 was removed from the second guide device 7.

  FIG. 6 is a graph showing the measurement result of the surface potential.

  The surface potential is measured by measuring the peripheral surface potential of the rotating photosensitive drum with the passage of time by installing an electrometer at the position indicated by DET in FIG. 6, and from the rotational speed of the photosensitive drum at the time of light emission. The potential at each position on the peripheral surface was obtained and graphed.

  The potential Va in the graph represents the potential on the peripheral surface of the photosensitive drum when the light shielding member 77 is provided, and the potential Vc in the graph represents the potential in the comparative example with the light shielding member 77 removed. In either case, a decrease in potential on the peripheral surface of the photosensitive drum near the transfer position T2 was observed. However, in the case of the configuration of the present embodiment having the light shielding member 77, the decrease in the potential Va is suppressed as compared with the comparative example. The decrease in the potential Va when the light shielding member 77 is provided is such that deterioration cannot be visually recognized in the image formed on the continuous paper P.

[Modification]
Next, a modification of this embodiment will be described. In the modification of this embodiment, the light shielding member provided in the 2nd guide apparatus 7 differs from the said embodiment, and other points are the same as the said embodiment.

  FIG. 7 is a plan view showing a light shielding member in a modified example. FIG. 7 shows the light shielding member in a state in which the edge facing the conveyance path is directed downward in the figure, as in FIG.

  The light shielding member 277 of FIG. 7 is incorporated in the edge portion 277a facing the conveyance path, that is, in the second guide device 7 (see FIG. 4), on the guide roll 71, that is, on the guide roll 71 and the transfer position T2. A light shielding film is affixed to a portion between the two.

  Also by the light shielding member 277 of the modified example shown in FIG. 7, the light reaching the second guide device 7 out of the light emitted from the first fixing device 9 </ b> A is reflected by the guide roll 71 and passes through the continuous paper P to the photosensitive drum 21. The amount of light that illuminates the portion before reaching the transfer position T2 is reduced. Accordingly, a decrease in the potential of the photosensitive drum 21 is suppressed, and deterioration such as blurring of the toner image is suppressed.

  In the above-described embodiment, as an example of the light shielding member according to the present invention, the light shielding member 77 having a structure in which a light shielding film is attached to the surface of a resin base material is shown. However, the present invention is not limited to this. For example, the light shielding member may be made of metal.

  In the above-described embodiment, the second guide device 7 is shown as an example of the upstream device according to the present invention. However, the present invention is not limited to this. For example, the upstream side apparatus may be a preliminary charging apparatus that charges continuous paper before transfer, and each part of the first toner image forming apparatus 1 may be used. There may be.

  Further, the fixing device in the above-described embodiment is a device that emits flash light. However, the present invention is not limited to this, and the fixing device may emit continuous light, for example.

  In the above-described embodiment, a roll-shaped photoconductor is shown as an example of the image carrier referred to in the present invention. However, the image carrier referred to in the present invention is not limited to this, and may be, for example, a belt-like member.

  In the above-described embodiment, as an example of the image forming apparatus, an apparatus that forms images on both the front and back sides of the continuous paper P in one apparatus is shown. However, the image forming apparatus referred to in the present invention is not limited to this. For example, the image forming apparatus may form an image on one side in one apparatus.

  In the above-described embodiment, a monochrome printer is shown as an example of the image forming apparatus. However, the image forming apparatus according to the present invention is not limited to this, and may be, for example, a color printer that forms a color image.

  In the above-described embodiment, a printer is shown as an example of the image forming apparatus. However, the image forming apparatus referred to in the present invention is not limited to a printer, and may be a copying machine or a facsimile, for example.

S image forming apparatus 1 first toner image forming apparatus 2 second toner image forming apparatus 3 first transfer apparatus 4 second transfer apparatus 5 paper transport apparatus 6 first guide apparatus 7 second guide apparatus 8 third guide apparatus 9A First fixing device 9B Second fixing device 11, 21 Photosensitive drum 71 Guide roll 71a Rotation center shaft 77,277 Light shielding member P Continuous paper R Conveying path

Claims (4)

A toner image forming apparatus that includes a photoreceptor that is charged and exposed to form an electrostatic latent image, and that forms an electrostatic latent image on the photoreceptor and develops it with toner;
A transport device that transports continuous paper along a transport path that passes through a transfer position that receives a transfer of a toner image on the photoreceptor;
A transfer device for transferring the toner image on the photoconductor onto the continuous paper at the transfer position;
The toner image is disposed on the downstream side of the conveyance path in the conveyance direction of the continuous paper with respect to the transfer position, and the toner image transferred onto the continuous paper is irradiated with light, and the toner image is applied onto the continuous paper by the heat of the light. A fixing device for fixing;
An upstream device that is disposed upstream of the transfer position in the transport direction of the continuous paper with respect to the transfer path and has a released space that allows the transfer position to be viewed, and that acts on the continuous paper; Have
The image forming apparatus, wherein the upstream apparatus includes a shielding member that shields light emitted from the fixing device on a side facing the transfer position.   The image forming apparatus according to claim 1, wherein the upstream device is a guide device including a guide roll that guides the continuous paper while rotating in contact with the continuous paper conveyed on the conveyance path.   The light-shielding member has a shape that protrudes from the position away from the conveyance path toward the conveyance path and extends toward the conveyance path from the plane including the rotation center axis of the guide roll and the transfer position. The image forming apparatus according to claim 2, wherein at least a region protruding from the plane toward the conveyance path is formed of a light shielding material. A toner image forming apparatus that includes a photosensitive member that is charged and exposed to form an electrostatic latent image, forms the electrostatic latent image on the photosensitive member, and develops the toner image with toner; and continuous paper A conveying device that conveys the toner image on the photoconductor along a conveyance path that passes through a transfer position, and a transfer device that transfers the toner image on the photoconductor onto the continuous paper at the transfer position. The toner image is disposed on the downstream side of the transport path in the transport direction of the continuous paper with respect to the transfer position, and the toner image transferred onto the continuous paper is irradiated with light so that the toner image is heated with the heat of the light. An image forming apparatus having a fixing device for fixing on a sheet is disposed at a position having an open space upstream of the transfer position in the conveyance direction of the continuous sheet and having a free space for viewing the transfer position. To guide continuous paper transported on the transport path An apparatus,
A guide roll for guiding the continuous paper while rotating in contact with the continuous paper;
A guide device comprising: a shielding member that is disposed on the transfer position side of the guide roll and shields light emitted from the fixing device.

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