JP4802719B2 - Image forming apparatus - Google Patents

Description

The present invention relates to an image forming apparatus for forming a toner image such as a copying machine or a printer using an electrophotographic system, an electrostatic recording system, or the like, and more particularly, an improvement of an image forming apparatus using a fixing device for heating a toner image. About.

  2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine or printer, when fixing an unfixed toner image formed on a recording material, a heating type fixing device is mainly used. In such a heating type fixing device, when the recording material is heated by the fixing device, moisture contained in the recording material evaporates, and in particular, evaporates to a guide chute adjacent to the downstream side of the fixing device to convey and guide the recording material. As a result, a large amount of moisture is deposited, and condensation occurs on the surface of the guide chute. Further, when the recording material heated by the fixing device passes through the guide chute, the guide chute is warmed, and the guide chute itself causes condensation.

  On the other hand, when water droplets due to such condensation adhere to the recording material passing through the guide chute, especially when image formation is performed on both sides of the recording material, there is insufficient charge (whiteout), etc. This causes image defects. In addition, the recording material that has become wet due to water droplets adhering to the recording material may stick to the guide chute and cause jamming, or the visibility of the discharged recording material may be impaired.

  To solve this problem, the guide chute provided with a longitudinal guide member along the recording material conveyance direction at the downstream position of the fixing device is used to reduce the contact area between the guide chute and the recording material and adhere to the guide chute. There is known a method for reducing the amount of moisture that adheres, that is, the amount of moisture that adheres to the conveyed recording material (see, for example, Patent Document 1).

JP-A-7-315623 (Example, FIG. 1)

FIG. 10 shows the above-described method, and an upper guide chute is provided on the downstream side of the fixing device 100 including a heating roll 101 having a built-in heater 101a and a pressure roll 102 arranged to face the heating roll 101. A pair of guide chutes comprising 104 and a lower guide chute 105 are provided. The upper guide chute 104 includes a plurality of vertical guide members 104a and a horizontal plate 104b that holds the vertical guide member 104a, and the lower guide chute 105 similarly includes a vertical guide member 105a and a horizontal plate 105b. ing. Reference numerals 106 and 107 in the drawing denote peeling claws that prevent the recording material 103 from being wound around the heating roll 101 and the pressure roll 102.
However, in such a type of guide chute, dew condensation occurs in places other than the vertical guide members 104a and 105a, for example, water drops fall from the horizontal plate 104b of the upper guide chute 104, or condensation on the side surfaces of the vertical guide member 104a. Due to the fall of the water droplets, the water droplets adhere to the recording material 103 being passed. For this reason, the above-described problems of white spots and sticking are not avoided.

The present invention has been made to solve the above technical problem, and in an image forming apparatus including a fixing device that fixes an unfixed toner image on a recording material by at least heating, the recording material after fixing It is an object of the present invention to provide an image forming apparatus that prevents water droplets from adhering to the surface.

That is, as shown in FIG. 1, the basic configuration of the present invention includes a toner image forming unit 2 that forms an unfixed toner image on a recording material 1, a fixing unit 3 that at least heat-fixes an unfixed toner image, and a guide chute 4 to rubbing can convey guide and the recording material 1 provided on one or both sides of the recording material conveyance path of the recording material conveying direction downstream side of the fixing means 3, the guide chute 4 includes at least a recording material A wire-shaped member 5 having a convex cross-sectional shape that extends in a direction having a conveyance direction component and protrudes without a corner portion with respect to the recording material conveyance path side, and a wire-shaped member 5 on a surface along the recording material conveyance path. And a holder 6 for supporting them so as to be spaced apart from each other through a space 7.

  In such technical means, the toner image forming means 2 is not particularly limited as long as a toner image can be formed, and a system such as an electrophotographic system or an electrostatic recording system is appropriately applied. The fixing unit 3 may be of a type that at least the recording material 1 is heated at the time of fixing. For example, the fixing unit 3 may be a type in which a fixing nip is formed by a heating roll and a pressure roll, or a near infrared ray is used. A lamp heater method, an IH method using induction heating, or the like may be used.

  Further, the guide chute 4 is only required to be disposed at least on the downstream side in the recording material conveyance direction of the fixing unit 3, and the number thereof is not particularly limited, and may be provided on the upstream side of the fixing unit 3. . Furthermore, by providing the guide chute 4 on one side or both sides of the recording material conveyance path, it is possible to improve the passage of vapor emitted from the high-temperature recording material 1 after fixing, and to suppress the occurrence of condensation on the guide chute 4. it can.

Since the wire-like member 5 of the present invention has a convex cross-sectional shape that extends at least in a direction having a recording material conveyance direction component and protrudes without a corner portion with respect to the recording material conveyance path side. The recording material 1 passing through the guide chute 4 is caught by the wire-like member 5 to cause jamming, or the recording material 1 is damaged by the friction between the surface of the wire-like member 5 and the recording material 1. The situation can be avoided.
In particular, when the guide chute 4 is disposed above the recording material conveyance path, the effect of suppressing the growth of condensation near the contact area with the recording material 1 is also achieved, thereby further preventing the influence of condensation. It becomes possible.

FIG. 2A shows a rubbing state between the wire-like member 5 and the recording material 1, and condensation occurs on the surface of the wire-like member 5 in the rubbing region between the wire-like member 5 and the recording material 1. However, the dew condensation caused by the rubbing of the recording material 1 passing therethrough is wiped off, and the dew condensation does not have an adverse effect. In addition, when water droplet adhesion due to condensation occurs in areas other than the rubbing region, the water droplets gradually reach downward and reach the rubbing region because the wire-like member 5 does not have a corner on the recording material conveyance surface side. The amount of water droplets staying on the wire-like member 5 is always kept small, and water droplet adhesion to the recording material 1 passing through the guide chute 4 can be suppressed.
On the other hand, as shown in FIG. 2 (b), assuming a conventional rectangular cross-sectional shape, in the sliding area with the recording material 1, there is no influence of condensation. At the lower end, it grows into large drops of water. When this lump exceeds a certain limit, it falls on the recording material 1 or adheres to the recording material 1 that is passing through, causing problems such as image defects and jams.
FIG. 2C shows a modification of the wire-like member 5, which has a convex cross-sectional shape with no corners on the recording material conveyance surface side. Therefore, even in this case, the same effect as (a) described above is obtained. Thus, the cross-sectional shape of the wire-like member 5 of the present invention is not limited to a circular shape, and may be, for example, an oval shape or an elliptical shape.

  The wire-like member 5 of the present invention is not particularly limited in its entire cross-sectional shape as long as it has a convex cross-sectional shape that protrudes without a corner on the recording material conveyance path side. The number used is not particularly limited. For example, one wire-like member 5 may be arranged so as to reciprocate and be stretched, or a plurality of wire-like members 5 may be stretched. .

The wire-like member 5 preferably has a substantially circular cross-sectional shape on the outer periphery. According to such a cross-sectional shape, the strength of the wire-like member 5 can be improved while reducing the surface area. It is possible to suppress the occurrence of condensation.
Furthermore, the wire-like member 5 is preferably provided so as to extend substantially parallel to each other along the recording material conveyance direction. By arranging the wire-like member 5 in this manner, the conveyance of the recording material 1 becomes smoother. Will be made.
Furthermore, in one aspect of the present invention, the wire-like member 5 is formed into a pipe shape, for example, and the heat generating portion is provided therein, so that condensation on the wire-like member 5 itself can be prevented.
Further, as the wire-like member 5, from the viewpoint of processability as a guide chute 4 and miniaturization, for example, a cross-section of φ6 mm or less is preferably a cylindrical or cylindrical wire, and the material is the shape of the guide chute 4. As long as it has rigidity that does not affect the recording material conveyance, it may be made of metal or resin, for example. In particular, the metal is excellent in workability, and the resin is difficult to condense in terms of heat capacity. Further, it may be made of resin, for example, to extend over the bag.

In particular, in the present invention, the holder 6 supports the wire-like member 5 so as to be spaced apart via the space 7, so that other uses (for example, dehumidification, etc.) using the space 7 can be effectively developed. become.
Further, the position of the holder 6 of the present invention is not particularly limited, and may be provided as long as it is provided at a position where the wire-like member 5 can be supported. However, if the holder 6 is provided on the inlet side and the outlet side of the guide chute 4, The wire-like member 5 can be fixed and arranged more stably, and installation in the apparatus is facilitated by using this holder 6.
Furthermore, if the guide chutes 4 are provided on both sides of the recording material conveyance path, the air flow can be improved so as to pass the guide chutes 4 through the spaces 7 between the wire-like members 5 that are spaced apart. It is also possible to reduce the occurrence of condensation.

Further, the guide chute 4 is preferably provided adjacent to the downstream side of the fixing unit 3 in the recording material conveyance direction. According to this, the influence of heating by the fixing unit 3 can be further reduced, and the preferred arrangement can be achieved. Become.
Further, it is preferable that a part of the guide chute 4 is provided with a conveying member capable of conveying the recording material 1, whereby the conveying property of the recording material 1 is stably secured and the conveying property is improved. In addition, as a specific aspect of a conveyance member, a conveyance roll (conveyance roll pair) is mentioned.

In the present invention, since the guide chute 4 includes the space 7, it is possible to provide a dehumidifying means for taking moisture in the atmosphere near the upper portion of the guide chute 4. In this case, effective dehumidification in the atmosphere is performed by this dehumidifying means, and it becomes possible to prevent condensation from occurring. The position where the dehumidifying means is provided is only required to be disposed at least above the guide chute 4, and the water evaporated from the recording material 1 can be effectively removed.
And as this dehumidification means, you may make it provide the cooling member which dehydrates by dehumidifying the water | moisture content in atmosphere, and may make it provide the dehumidification member which adsorb | sucks moisture in an atmosphere directly and dehumidifies. Although it does not specifically limit as a cooling member, What is necessary is just to provide many metal fins and to condense and collect on this fin as a simple and cheap structure. Further, as the dehumidifying member, for example, a dehumidifying agent that adsorbs ordinary moisture may be used.
As one aspect of the present invention having such dehumidifying means, the dehumidifying means includes a cooling member for condensing moisture in the atmosphere, and the water droplets so that the water droplets condensed by the cooling member do not fall on the guide chute. And a water drop receiver.

  In the present invention, it is preferable to provide a cooling device that cools the recording material 1 passing through the guide chute 4 at least in the vicinity of the upper side of the guide chute 4. By providing the cooling device in this way, the space 7 is used. As a result, the recording material 1 can be cooled, moisture evaporation from the recording material 1 can be suppressed, and the occurrence of condensation can be suppressed. In addition, a cooling fan is mentioned as a specific aspect of a cooling device.

The present invention is directed to an image forming apparatus described above.

According to the present invention, a toner image forming unit, a fixing unit at least heat-fixing an unfixed toner image, and a recording material provided on one or both sides of the recording material conveyance path of the recording material conveying direction downstream side of the fixing means A convex cross section that extends in a direction having at least a recording material conveyance direction component and protrudes without a corner with respect to the recording material conveyance path side in an image forming apparatus having a guide chute that conveys and guides the recording material in a slidable manner Since a guide chute comprising a wire-shaped member having a shape and a holder for supporting the wire-shaped member so as to be spaced apart from each other on a surface along the recording material conveyance path is used, high-temperature recording after fixing The steam emitted from the material is improved, and the occurrence of condensation can be suppressed. In particular, by providing a heat generating part inside the wire-like member, it is possible to suppress the occurrence of condensation on the surface of the guide chute and prevent water droplets from adhering to the recording material.
In addition, other uses such as dehumidification can be easily developed by utilizing the space between the wire-like members. For example, if the recording material is cooled by a cooling device, blocking with the discharged recording material is possible. It is also possible to easily prevent the occurrence of (a phenomenon in which toner is discharged in a state where the toner is not completely solidified and solidified in a state where a plurality of recording materials are overlapped). In particular, a dehumidifying means for removing moisture in the atmosphere is provided near the upper portion of the guide chute. As this dehumidifying means, a cooling member for condensing moisture in the atmosphere and water droplets condensed by the cooling member fall on the guide chute. In order to prevent this, the water droplet receiving portion that receives the water droplets is provided, so that the water droplets can be prevented from adhering to the recording material.
Therefore, it is possible to provide an image forming apparatus that suppresses the influence of condensation. Further, it is possible to provide a guide chute used in such an image forming apparatus.

Hereinafter, the present invention will be described in detail based on embodiments shown in the accompanying drawings.
Embodiment 1
FIG. 3 shows Embodiment 1 of an image forming apparatus using a guide chute to which the basic configuration of the present invention is applied. In the figure, the image forming apparatus according to the present embodiment employs, for example, an electrophotographic system, and includes yellow (Y color), magenta (M color), cyan (C color), and black (K color). An image forming unit 10 for forming a four-color toner image, a paper feeding unit 50 for supplying paper as a recording material to the image forming unit 10, an image reading unit 60 for reading a document image and converting it into digital information, and a paper after image formation It is comprised in the paper conveyance unit 70 which conveys.

The image forming unit 10 has a so-called quadruple tandem configuration in which image forming units 20 (20a to 20d) for sequentially forming toner images of respective colors are arranged in parallel on the intermediate transfer belt 30.
The image forming unit 20 includes a photosensitive drum 21 that forms and carries a toner image, facing the intermediate transfer belt 30, and a photosensitive drum 21 that is not shown is charged around the photosensitive drum 21. The charging device, an exposure device 22 such as a laser scanner that forms an electrostatic latent image on the charged photosensitive drum 21, and a toner image by supplying toner to the electrostatic latent image on the photosensitive drum 21 (development image) The primary transfer unit 24 and the photoconductive drum which are arranged opposite to each other with the developing unit 23 and the photoconductive drum 21 sandwiching the intermediate transfer belt 30 and which primarily transfer the color toner images on the photoconductive drum 21 onto the intermediate transfer belt 30. A photoreceptor cleaner (not shown) that cleans residual toner on 21 is disposed.

  The intermediate transfer belt 30 is stretched around a plurality of stretching rolls 31 to 35, and is circulated and moved, for example, with the stretching roll 31 as a driving roll and the stretching roll 33 as a tension roll. Then, at a position facing the tension roll 34 and the intermediate transfer belt 30, the secondary transfer that collectively transfers the toner images multiplexed on the intermediate transfer belt 30 onto the sheet conveyed from the paper supply unit 50. A secondary transfer device 36 such as a roll is provided, and a predetermined secondary transfer bias is applied between the stretching roll 34 as a backup roll.

On the upstream side of the secondary transfer portion (position of the secondary transfer device 36) in the paper transport direction, the registration roll 11 that temporarily positions and feeds the paper supplied from the paper supply unit 50 before the secondary transfer and appropriately A number of transport rolls (pairs of transport rolls) are provided. On the other hand, on the downstream side of the secondary transfer portion, a conveyance belt 12 that conveys the sheet after the secondary transfer, and a fixing device 13 that fixes an unfixed toner image on the sheet conveyed by the conveyance belt 12 are provided. .
The registration roll 11 is configured to adjust the arrival timing of the sheet relative to the image output position by a timing adjustment unit (not shown) when the sheet is fed.

  The fixing device 13 in the present embodiment is a so-called free belt nip type constituted by a fixing roll 13a having a heating source and an endless belt 13b stretched between a plurality of stretch rolls. The unfixed toner image on the paper is fixed in the nip area with the endless belt 13b.

The downstream side of the fixing device 13 is divided into a path connected to the sheet conveyance unit 70 side and a path descending substantially vertically. A guide chute 40 that removes condensation in the path is provided along with the transport rolls on the descending path (reverse transport path R5 described later).
Further, below the image forming unit 10, a path (return conveyance path R <b> 6 described later) provided with an appropriate number of conveyance members such as conveyance rolls is disposed.

  Further, the paper feeding unit 50 of the present embodiment accommodates a plurality of paper feeding cassettes 51 to 53 that can supply paper, and is provided in the vicinity of each of the paper feeding cassettes 51 to 53. Feeding rolls 54 to 56 corresponding to each are arranged. These feed rolls 54 to 56 are for feeding only one uppermost sheet from the corresponding sheet feed cassettes 51 to 53 and feeding them to the downstream side.

  Further, the image reading unit 60 reads an image of a document set on a transparent document table (platen glass). For example, an optical scanning system including a lamp, a mirror, a carriage, and the like, and scanning by the optical scanning system are performed. The lens system includes an optical image formed by the lens system, and an image reading sensor (for example, a CCD sensor) that receives the optical image formed by the lens system and converts it into an electrical signal. An operation panel 61 operated by a user is provided in the vicinity of the image reading unit 60.

  Furthermore, the paper transport unit 70 disposed on the downstream side of the image forming unit 10 is provided with a guide chute 80, and the paper passing through the guide chute 80 passes through a path branched into two paths on the way. The paper is discharged to a discharge tray 71 provided on the side wall of the transport unit 70.

Here, a paper conveyance system in the image forming apparatus of the present embodiment will be described.
The sheets fed from the respective sheet feeding cassettes 51 to 53 in the sheet feeding unit 50 are conveyed by the respective feeding rolls 54 to 56, and the sheets fed from the sheet feeding cassettes 51 and 52 are passed through the sheet conveying path R1. On the other hand, the sheet fed from the sheet feeding cassette 53 is guided to the merging / conveying section 57 via the sheet conveying path R2.
The sheet guided to the merging / conveying section 57 is conveyed to the main conveyance path R3 and is positioned and regulated by the registration roll 11, and then the multiplexed toner image on the intermediate transfer belt 30 is collectively put on the sheet by the secondary transfer unit 36. Transcribed. The sheet on which the toner image is transferred is guided to the fixing device 13 by the conveyance belt 12. The sheet that has been fixed is discharged to the discharge tray 71 via the sheet transport path R4 in the sheet transport unit 70.

On the other hand, in order to form a new image (double-sided image formation) on the back side of the paper fixed by the fixing device 13, a reverse conveyance path R5 for reversely conveying the paper is provided on the downstream side of the fixing device 13. A return conveyance path R6 that is connected in the middle of the reverse conveyance path R5 and guides the reversed sheet to the merging conveyance section 57 is provided.
Needless to say, an appropriate number of conveying members (conveying rolls, conveying guides, etc.) are provided in the sheet conveying paths R1 to R6. In the figure, reference numerals 15 and 72 denote curl correction units provided in the return conveyance path R6 and the sheet conveyance path R4 in the sheet conveyance unit 70, for correcting the curl of the sheet generated in the fixing device 13. It has become a thing.

  And the guide chute | shoot 40 of this Embodiment is as shown in FIG. In the figure, a guide chute 40 according to the present embodiment is constituted by two guide chutes 41 and 46 (specifically, an upper guide chute 41 and a lower guide chute 46) provided on both sides of the sheet conveying path. The sheet is conveyed between these. For example, the upper guide chute 41 on the toner image surface (fixed toner image surface) side of the paper has metal holders 42 and 43 extending in a direction substantially perpendicular to the paper transport direction on the entrance side and the exit side in the paper transport direction. A plurality of wire rods (wire-like members) 44 (13 in this example) are stretched between the holders 42 and 43 along the paper transport direction. As the wire 44, for example, a metal rod having a diameter of about 5 mm is used, and is fixed to the holders 42 and 43 by a technique such as welding in the vicinity of both ends. Further, the stretched wire 44 is separated. Therefore, a space is maintained between the wire members 44.

Also, the lower guide chute 46 on the opposite side of the toner image surface of the paper is configured in substantially the same manner as the upper guide chute 41, and has holders 47, 48 on the entrance side and the exit side in the paper transport direction. A plurality of wires 44 (16 in this example) are stretched between 48 along the paper conveyance direction.
In such a guide chute 40, for example, the respective holders 42, 43, 47, and 48 are fixedly supported on the frame of the image forming unit 10, and a stable paper conveyance path is provided between the upper guide chute 41 and the lower guide chute 46. Is to be formed. Two pairs of conveyance rolls are mounted inside to ensure the conveyance of the paper within the guide chute 40.

  Further, in the present embodiment, a guide chute 80 similar to the guide chute 40 described above is also provided in the paper transport path R4 in the paper transport unit 70. Since this guide chute 80 is also the same as that in FIG. 3, the details thereof are omitted here. The guide chute 80 is provided with only one pair of transport rolls.

  Next, the operation of the image forming apparatus in the present embodiment will be described. First, when a document image is read by the image reading unit 60, a toner image is formed by the image forming unit 10 based on an image signal obtained thereby. In the image forming unit 10, toner images of the respective colors are formed on the respective photosensitive drums 21 by the four color image forming units 20 (20 a to 20 d). Each color toner image formed in this way is sequentially transferred onto the intermediate transfer belt 30 by the primary transfer unit 24, and a multiplexed toner image is formed on the intermediate transfer belt 30. The toner images multiplexed on the intermediate transfer belt 30 in this way are carried on the intermediate transfer belt 30 as they are and sent to the secondary transfer site.

On the other hand, the sheet fed from the sheet feeding cassette selected from the sheet feeding cassettes 51 to 53 using the operation panel 61 is sent to the merging / conveying unit 57 from the sheet conveying path R1 or the sheet conveying path R2. It is sent to the secondary transfer portion by the resist roll 11 via the transport path R3.
At the secondary transfer portion, the toner image carried on the intermediate transfer belt 30 is collectively transferred onto the sheet by the action of the secondary transfer device 36 and the backup roll 34. Thereafter, the paper is guided from the transport belt 12 to the fixing device 13 and subjected to a toner image fixing process, and then discharged to the discharge tray 71 via the paper transport path R4.

  When image formation is performed on both sides of the paper, the paper fixed by the fixing device 13 proceeds to the reverse conveyance path R5, and the trailing edge of the paper is the junction of the reverse conveyance path R5 and the return conveyance path R6. It is conveyed as it is until it passes. The sheet that has passed the merging point is conveyed to the return conveyance path R6 by a predetermined conveyance roll performing a reversal operation, and is conveyed as it is to the merging conveyance unit 57. Then, the same operation as described above is performed from the merging and conveying unit 57, and images are formed on both sides of the sheet.

  Next, the operation of the guide chutes 40 and 80 in the present embodiment will be described. Here, since the two guide chutes 40 and 80 both exhibit the same operation, only the guide chute 40 provided in the reverse conveyance path R5 on the image forming unit 10 side will be described in detail below.

Since the guide chute 40 of the present embodiment is provided at a position adjacent to the downstream side of the fixing device 13 and in the reverse conveyance path R5, the sheet heated by the fixing device 13 passes through the guide chute 40. When doing so, much of the water in the paper is evaporated. However, in the present embodiment, the wire 44 of the guide chute 40 is disposed separately (having a space), so that the vapor (evaporated water) emitted from the paper in the guide chute 40 is the guide chute. It spreads to the outside (particularly upward) through 40, and a local increase in temperature and humidity in the guide chute 40 can be suppressed.
Further, since the cross-sectional shape of the wire 44 of the guide chute 40 is circular, a predetermined strength of the wire 44 can be realized with a smaller surface area, and the occurrence of condensation on the surface of the wire 44 can be reduced. Become. Furthermore, since the wire 44 is disposed along the paper transport direction, the paper transport performance of the guide chute 40 is not impaired during the paper transport. In particular, such a shape is suitable when, for example, an OHP sheet is used as the paper, and the surface of the guide chute 40 can be prevented from being damaged when the OHP sheet is conveyed.

As described above, in this embodiment, there is no scratches or adhesion of water droplets due to condensation on the paper guided to the reverse conveyance path R5 during double-sided output, and a uniform toner image is formed on the back side. As a result, image transfer such as white spots can be prevented.
Similarly, by providing the guide chute 80 in the paper transport path R4, even when the paper heated by the fixing device 13 passes through the guide chute 80, even if moisture in the paper evaporates, Since the temperature and humidity of the paper does not rise significantly, the occurrence of condensation is suppressed, and the air flow through the guide chute 80 is good, so that the paper is easily cooled accordingly, and the paper discharged from the discharge tray 71 It is also possible to prevent blocking due to.

Here, FIG. 5 shows a conventional type guide chute 110 shown as a comparative example of the guide chute 40 of the present embodiment, and only the lower guide chute is shown in the figure. In the figure, a guide chute 110 includes, for example, a guide main body 111 constituted by a sheet metal part obtained by appropriately bending a metal plate, and a plurality of protrusions 112 protruding from the guide main body 111 toward the paper conveyance path (in this example, for example, embossing). 7), for example, a plurality of holes 113 into which the transport rolls are inserted and holes 114 appropriately provided for ventilation.
If such a guide chute 110 is provided on the downstream side of the fixing device, the air permeability of the guide chute 110 itself is poor, and in particular, condensation on the surface of the guide main body 111 is likely to occur. For example, image defects such as white spots are likely to occur during double-sided output, while jamming or the like occurs during single-sided output.

In the present embodiment, the guide chutes 40 and 80 are provided adjacent to the fixing device 13 and provided in the reverse conveyance path R5 and the sheet conveyance path R4 on the downstream side. However, such guide chutes are provided in other parts. It does not matter if it is provided.
In this embodiment, metal is used as the wire 44 of the guide chutes 40, 80. However, in order to prevent condensation on the guide chutes 40, 80 themselves, for example, a resin coating is applied on the metal, The thermal conductivity may be reduced, or the wire 44 itself may be made of, for example, a molded resin. Further, for example, iron wire may be used as the wire rod 44, and a protrusion or a cut groove may be provided in the corresponding support portion, and the iron wire may be fixed by being wound around these.

  Further, in the present embodiment, an aspect in which image formation is performed based on image information from the image reading unit 60 has been described. However, for example, digital data may be input to the image forming unit 10 for image formation.

Further, FIG. 6 shows a modification of the guide chute 40 of the present embodiment, which is a guide chute 40 to which the present invention is applied. In the figure, only the lower guide chute 46 is shown.
In the figure, the lower guide chute 46 uses a single sheathed heater 441 as a wire 44 between the upstream and downstream holders 47 and 48 in the paper transport direction. The connection point between the sheathed heater 441 and the holders 47 and 48 is fixed by bending the sheathed heater 441 to the extent that the sheathed heater 441 is not damaged and brazing the holders 47 and 48. For this reason, the surface of the sheathed heater 441 does not impair the paper transportability. A predetermined electric field can be applied to both end portions 441a and 441b of the sheathed heater 441.
By using the guide chute 40 like this, the guide chute 40 itself can generate heat, and even if moisture evaporates from the paper after fixing, the temperature of the guide chute 40 is raised, so the guide chute 40 itself Condensation can be prevented and the occurrence of condensation itself can be suppressed.

Embodiment 2
FIG. 7 shows an outline of a guide chute 40 used in the image forming apparatus according to the second embodiment to which the present invention is applied. In the present embodiment, the configuration of the fixing device is different from that of the first embodiment, and a fixing device 90 having a roll pair configuration with a heating roll 91 and a pressure roll 92 is provided. Further, the guide chute 40 is the same as that of the first embodiment (shown in FIG. 3), and in this embodiment, the guide chute 40 is disposed adjacent to the fixing device 90. Here, for the sake of simplicity, only the cross section of the guide chute 40 is schematically shown.

  In the present embodiment, a cooling member 93 as a dehumidifying means is provided above the guide chute 40 and above the fixing device 90. The cooling member 93 supports a metal support part 93b with a hole and a large number of metal rods (fins) 93a on the support part 93b, and cools the fins 93a on a side different from the fins 93a of the support part 93b. Therefore, the fan 93c is provided. And the fin 93a is installed so that it may become diagonally downward toward the support part 93b.

Due to such a configuration, the paper fixed by the fixing device 90 evaporates moisture in the paper at the guide chute 40. The vapor emitted from the paper easily rises through the space of the guide chute 40 (the gap between the wires) and reaches the fins 93a of the cooling member 93. Since the fins 93a are cooled by the fans 93c, the vapor that reaches the periphery of the fins 93a is condensed and attached, resulting in water droplets. The water droplets do not fall toward the guide chute 40 but flow down the fins 93a and flow down toward the support portion 93b.
In particular, in the present embodiment, a pan 94 is provided on the upper part of the fixing device 90 to prevent water droplets from dropping toward the guide chute 40 side. The water drops falling on the pan 94 gradually evaporate and disappear due to the ambient temperature environment and the influence of the fan 94, so there is almost no need to consider the influence of the water drops on the pan 94 on the paper.

As described above, in the present embodiment, it is possible to efficiently remove the steam emitted from the paper passing through the guide chute 40, and it is possible to prevent unnecessary condensation from occurring on the guide chute 40. Further, since the space is provided in both the upper guide chute 41 and the lower guide chute 46 of the guide chute 40, the air permeability of the guide chute 40 is ensured, and the steam emitted from the paper is efficiently transferred to the cooling member 93 side. Can be reached.
In the present embodiment, the fins 93a of the cooling member 93 have a rod shape, but this shape is not particularly limited, and may be, for example, a plate shape as long as dehumidification is performed effectively.

Embodiment 3
FIG. 8 shows an outline of a guide chute 40 used in the image forming apparatus according to the third embodiment to which the basic configuration of the present invention is applied. The fixing device in the present embodiment is the same as that in the second embodiment, and is a fixing device 90 having a roll pair configuration with a heating roll 91 and a pressure roll 92. Further, the guide chute 40 is the same as that of the first embodiment (shown in FIG. 3), and in this embodiment, the guide chute 40 is disposed adjacent to the fixing device 90. Here, for the sake of simplification, only the cross section of the guide chute 40 is schematically shown as in the second embodiment.

  In the present embodiment, a dehumidifying agent 95 as a dehumidifying means is provided above the guide chute 40. The dehumidifying agent 95 is formed by flattening particles such as silica gel and calcium chloride with a breathable packaging, and can absorb moisture in the atmosphere. The amount of the dehumidifying agent 95 to be installed is not particularly limited, and it is preferable to dispose the dehumidifying agent 95 above the guide chute 40 from the viewpoint of absorbing moisture, but it may be provided below the guide chute 40. Absent. Note that the dehumidifying agent 95 is not limited to the above-described one, and may be any one that adsorbs moisture in the air.

  Since the present embodiment has such a configuration, the paper fixed by the fixing device 90 diffuses moisture in the paper at the guide chute 40. The emitted steam easily rises through the space of the guide chute 40 (the gap between the wire rods), reaches the dehumidifying agent 95, and is absorbed. Therefore, it is possible to prevent the occurrence of excessive dew condensation on the guide chute 40 and prevent moisture from adhering to the paper. Needless to say, the dehumidifying agent 95 is appropriately replaced to maintain the dehumidifying function.

  As described above, in the present embodiment, it is possible to efficiently remove the steam emitted from the paper passing through the guide chute 40, and it is possible to prevent unnecessary condensation from occurring on the guide chute 40. Further, since the space is provided in both the upper guide chute 41 and the lower guide chute 46 of the guide chute 40, the air permeability of the guide chute 40 is ensured, and the steam emitted from the paper is efficiently moved to the dehumidifying agent 95 side. Can be reached.

Embodiment 4
FIG. 9 shows an outline of a guide chute 40 used in the image forming apparatus according to the fourth embodiment to which the basic configuration of the present invention is applied. The fixing device in the present embodiment is the same as that in the second embodiment, and is a fixing device 90 having a roll pair configuration with a heating roll 91 and a pressure roll 92. Further, the guide chute 40 is the same as that of the first embodiment (shown in FIG. 3), and in this embodiment, the guide chute 40 is disposed adjacent to the fixing device 90. Here, for the sake of simplification, only the cross section of the guide chute 40 is schematically shown as in the second embodiment.

In the present embodiment, fans 96 and 97 as cooling devices are provided above and below the guide chute 40, and the air from these fans 96 and 97 is installed so as to go to the guide chute 40.
Since both the upper guide chute 41 and the lower guide chute 46 of the guide chute 40 are provided with a space, the air blown from the fans 96 and 97 directly hits the paper passing through the guide chute 40. It is possible to cool the sheet, and moisture from the sheet heated by fixing can be suppressed. Therefore, it is possible to suppress the occurrence of condensation on the guide chute 40 and prevent moisture from adhering to the paper.

  In the present embodiment, the configuration in which the fans 96 and 97 are provided on both sides of the guide chute 40 is shown. However, the present invention is not particularly limited to this, and if it is provided on one side, the sheet conveyed through the guide chute 40 is cooled. The same effect can be achieved.

1 is an explanatory diagram showing an outline of an image forming apparatus according to the present invention. It is explanatory drawing which shows the cross-sectional shape effect of the wire-shaped member of this invention, (a) is the wire-shaped member of this invention, (b) is a member as a comparison, (c) shows the modification of this invention. 1 is an explanatory diagram showing an overview of Embodiment 1 of an image forming apparatus according to the present invention. FIG. 3 is an explanatory diagram illustrating an outline of a guide chute according to the first embodiment. It is explanatory drawing which shows the outline | summary of the guide chute | shoot as a comparative example. It is explanatory drawing which shows the modification of the guide chute | shoot of Embodiment 1. FIG. FIG. 10 is an explanatory diagram showing an outline of a guide chute site used in the image forming apparatus according to the second embodiment. FIG. 10 is an explanatory diagram showing an outline of a guide chute site used in an image forming apparatus according to a third embodiment. FIG. 10 is an explanatory diagram showing an outline of a guide chute site used in an image forming apparatus according to a fourth embodiment. FIG. 10 is an explanatory diagram illustrating a paper guide method around a fixing device as a conventional example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Recording material, 2 ... Toner image formation means, 3 ... Fixing means, 4 ... Guide chute, 5 ... Wire-shaped member, 6 ... Holder, 7 ... Space

Claims (5)

Toner image forming means for forming an unfixed toner image on the recording material;
Fixing means for fixing at least an unfixed toner image by heating;
And a guide chute for rubbing capable transporting guiding one side or provided on both sides and the recording material of the recording material conveyance direction downstream side of the recording material conveying path of the fixing means,
The guide chute extends in a direction having at least a recording material conveyance direction component and has a convex cross-sectional shape protruding without a corner portion with respect to the recording material conveyance path side, and along the recording material conveyance path A holder for supporting the wire-like member so as to be spaced apart from each other through a space on the surface ,
The image forming apparatus according to claim 1, wherein the wire-like member includes a heat generating portion therein . Toner image forming means for forming an unfixed toner image on the recording material;
Fixing means for fixing at least an unfixed toner image by heating;
And a guide chute for rubbing capable transporting guiding one side or provided on both sides and the recording material of the recording material conveyance direction downstream side of the recording material conveying path of the fixing means,
The guide chute extends in a direction having at least a recording material conveyance direction component and has a convex cross-sectional shape protruding without a corner portion with respect to the recording material conveyance path side, and along the recording material conveyance path A holder for supporting the wire-like member so as to be spaced apart from each other through a space on the surface ,
A dehumidifying means for removing moisture in the atmosphere near the upper part of the guide chute,
The dehumidifying means includes a cooling member for condensing moisture in the atmosphere, and a water droplet receiver that receives the water droplets so that the water droplets condensed by the cooling member do not fall on the guide chute. An image forming apparatus. The image forming apparatus according to claim 1, wherein
2. The image forming apparatus according to claim 1, wherein the wire member has a substantially circular cross-sectional shape on the outer periphery. The image forming apparatus according to claim 1, wherein
The image forming apparatus according to claim 1, wherein the wire-like member is provided so as to extend substantially in parallel along a recording material conveyance direction. The image forming apparatus according to claim 1, wherein
An image forming apparatus, wherein the guide chute is provided on both sides of the recording material conveyance path.

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