JP6303807B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  In recent years, image forming apparatuses such as copying machines or printers have been required to reduce costs and save space. Since the image forming apparatus has a plurality of rollers, it is possible to realize cost reduction and space saving of the image forming apparatus by shortening the distance between the rollers and shortening the sheet conveyance path.

  On the other hand, generally, it is required to regulate the behavior of a sheet while suppressing a load (conveying load) applied to the sheet when the sheet (sheet) is conveyed. For example, a guide member is provided in the paper transport path to regulate the behavior of the paper and to adjust the posture of the paper when the paper is transported.

  However, if the paper transport path is shortened, it becomes difficult to regulate the behavior of the paper. Hereinafter, an example in which the distance from the transfer unit to the fixing unit of the image forming apparatus is shortened will be described. As the distance from the transfer unit to the fixing unit becomes shorter, it becomes more difficult to regulate the behavior of the sheet due to the influence of the tension of the sheet (the waist of the sheet). For example, since the trailing edge of the paper strongly jumps as soon as the paper comes out of the transfer nip of the transfer portion, it becomes difficult to regulate the behavior of the paper. Since an image is formed on the sheet between the transfer unit and the fixing unit, toner adheres to the sheet. Therefore, the behavior of the paper cannot be regulated from both sides of the paper. As a result, the trailing edge of the sheet may come into contact with the photosensitive drum of the transfer unit due to the jumping of the trailing edge of the sheet.

  In general, in order to suppress the contact of the sheet with the photosensitive drum due to the splash of the sheet, the leading end of a guide member that guides the sheet to the fixing unit is brought into strong contact with the sheet to regulate the behavior of the sheet. However, since the guide member is brought into strong contact with the sheet, the sheet conveyance load increases. Therefore, in the transport device described in Patent Document 1, the behavior of the paper is regulated by reducing the paper transport load by forming a paper transport path that is greatly curved.

JP 2006-96527 A

  However, in the conveyance device described in Patent Document 1, since a sheet conveyance path is formed by a pair of guide members, an image is formed on the sheet when applied to the sheet conveyance path between the transfer unit and the fixing unit. The surface being in contact with one of the pair of guide members. Therefore, the recording medium conveyance device described in Patent Document 1 cannot be applied to the paper conveyance path between the transfer unit and the fixing unit.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device and an image forming apparatus that can regulate the behavior of a sheet while reducing the sheet conveyance load.

  According to a first aspect of the present invention, a fixing device includes a fixing unit and a guide member. The fixing unit fixes the image formed on the sheet to the sheet. The guide member has a guide surface for guiding the sheet to the fixing unit along the sheet conveyance path. The guide member includes a rotating member. The rotating member is disposed at a downstream end of the guide member in the sheet conveying direction. The rotating member protrudes toward the sheet conveyance path from the guide surface.

  According to a second aspect of the present invention, an image forming apparatus includes the fixing device according to the first aspect of the present invention and an image forming unit. The image forming unit forms the image on the sheet.

  According to the present invention, the behavior of a sheet can be regulated while reducing the sheet conveyance load.

1 is a schematic diagram illustrating a fixing device according to Embodiment 1 of the present invention. FIG. 3 is a perspective view illustrating a guide member of the fixing device according to the first exemplary embodiment of the present invention. 2A and 2B are perspective views illustrating a guide roller, a cleaning member, and a receiving portion provided in a guide member of the fixing device according to the first exemplary embodiment of the present invention. FIG. 4 is a schematic cross-sectional view taken along line IV-IV shown in FIG. 3. (A) (b) It is a schematic diagram explaining the 1st press member of the fixing device which concerns on the modification of Embodiment 1 of this invention. It is a schematic diagram which shows the outline of the image forming apparatus which concerns on Embodiment 2 of this invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof is not repeated. In the present embodiment, the X axis and the Y axis are parallel to the horizontal plane, and the Z axis is parallel to the vertical line.

(Embodiment 1)
A fixing device 1 according to a first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a schematic diagram illustrating the fixing device 1 and the transfer unit 151. The fixing device 1 and the transfer unit 151 are provided in the image forming apparatus.

  The transfer unit 151 includes a photosensitive drum 151a and a transfer roller 151b. The photosensitive drum 151a forms a transfer nip Nt together with the transfer roller 151b, and forms an image (a toner image in the first embodiment) on the image forming surface S1 of the sheet S passing through the transfer nip Nt. The image forming surface S1 is a surface of the sheet S on which an image to be fixed is formed. The sheet S that has passed through the transfer nip Nt is guided along the sheet conveyance path P by the guide member 70 and further guided to the fixing unit 10 by the guide member 20.

  The fixing device 1 is disposed upstream of the transfer unit 151 in the sheet conveyance direction D. The fixing device 1 includes a fixing unit 10 and a guide member 20. The fixing unit 10 fixes the image formed on the sheet S to the sheet S. The fixing unit 10 includes a heating roller 11 and a pressure roller 13. The heating roller 11 heats the sheet. The pressure roller 13 presses the sheet toward the heating roller 11. As the sheet S passes through the fixing nip Nf formed by the heating roller 11 and the pressure roller 13, the toner on the surface of the sheet S is heated, melted and pressed, and the image is fixed to the sheet S.

  The guide member 20 has a guide surface 30 and is disposed in the sheet conveyance path P between the transfer unit 151 and the fixing unit 10. The guide surface 30 guides the sheet S to the fixing unit 10 along the sheet conveyance path P. The guide surface 30 faces the surface S2 opposite to the image forming surface S1.

  The guide member 20 includes a guide roller 40 as a rotating member. The guide roller 40 is a driven roller that is not connected to a drive source such as a motor. The guide roller 40 is disposed at the downstream end of the guide member 20 in the sheet conveyance direction D. The guide roller 40 is rotatably supported at the downstream end portion of the guide member 20. The guide roller 40 protrudes from the guide surface 30 toward the sheet conveyance path P. Accordingly, the guide roller 40 contacts the sheet S conveyed in the sheet conveyance direction D, is rotated in the rotation direction R by the sheet S, and smoothly guides the sheet S to the fixing unit 10. As a result, according to the first embodiment, the behavior of the sheet S can be regulated while reducing the conveyance load of the sheet S. Even when the distance between the transfer unit 151 and the fixing unit 10 is shortened to realize space saving, similarly, the behavior of the sheet S can be regulated while reducing the conveyance load of the sheet S.

  Further, according to the fixing device of the first exemplary embodiment, the behavior of the sheet S is regulated by the downstream end portion (including the guide roller 40) of the guide member 20, and therefore, as soon as the sheet S comes out of the transfer nip Nt. Bounce of the rear end portion of the sheet S can be suppressed, and contact of the rear end portion of the sheet S with the photosensitive drum 151a can be suppressed. The rear end portion of the sheet S is an upstream end portion of the sheet S in the sheet conveying direction D. Further, the sheet S is regulated by the downstream end portion of the guide member 20. That is, since the sheet S is pressed by the guide roller 40 protruding from the guide surface 30 of the guide member 20, the sheet S can be prevented from wrinkling and the width of the sheet S can be made uniform.

  Further, according to the first embodiment, since the guide roller 40 is rotated by the contact of the sheet S, it is possible to suppress the sheet S from being rubbed strongly against the downstream end portion of the guide member 20. As a result, the generation and remaining of paper dust is suppressed, and operation failure and image failure due to paper dust can be suppressed.

  Furthermore, according to the first embodiment, the following effects are obtained. That is, when performing double-sided printing or using the backing paper, an image is also formed on the opposite surface S2 of the sheet S, so that the toner also adheres to the opposite surface S2. In addition, the vicinity of the heating roller 11 is relatively high temperature. Therefore, in the vicinity of the heating roller 11, the toner attached to the opposite surface S <b> 2 is more easily scraped than at normal temperature.

  However, according to the first embodiment, since the guide roller 40 is rotated by the contact of the sheet S, it is suppressed that the sheet S is rubbed strongly against the downstream end portion of the guide member 20. Accordingly, the toner attached to the opposite surface S <b> 2 of the sheet S is suppressed from being scraped, and as a result, the toner can be suppressed from remaining at the downstream end of the guide member 20. As a result, it is possible to suppress the occurrence of jam due to the remaining toner. Further, since the toner residue can be suppressed, it is possible to suppress the toner from adhering to the opposite surface S2 of the subsequent sheet S. As a result, image defects on the opposite surface S2 during double-sided printing can be prevented, and contamination of the opposite surface S2 during single-sided printing can be prevented.

  Further, according to the first embodiment, the guide member 20 is disposed such that the downstream end portion of the guide member 20 is closer to the heating roller 11 than the pressure roller 13 is. As a result, the preheating effect of the sheet S can be improved, and the fixing of the image (toner image) to the sheet S is facilitated. As a result, the fixing performance by the fixing unit 10 is further improved.

  Details of the guide member 20 will be described with reference to FIGS. 1 and 2. FIG. 2 is a perspective view showing the guide member 20. A curved surface 21 is formed at the downstream end of the sheet conveying path P in the guide member 20. The curved surface 21 is curved in a convex shape toward the sheet conveyance path P. Accordingly, the sheet S is conveyed while being curved along the curved surface 21, and thus is urged toward the guide member 70. Accordingly, the sheet S is conveyed while being curved along the curved surface 21. That is, the sheet S is curved in a convex shape toward the sheet conveyance path P with the two side edges of the sheet S as both ends. As a result, the rear end portion of the sheet S is urged toward the guide member 70, and it is possible to further suppress the jump of the rear end portion of the sheet S as soon as the sheet S comes out of the transfer nip Nt. It can further suppress that an edge part contacts photoconductor drum 151a. That is, the behavior of the sheet S can be more appropriately regulated.

  The guide roller 40 is disposed in a central region of the downstream end portion of the guide member 20 in the Y-axis direction (a direction orthogonal to the sheet conveying direction D). That is, the guide roller 40 is disposed in the apex region of the curved surface 21. The apex region of the curved surface 21 is a central region of the curved surface 21 in the Y-axis direction. Since the guide roller 40 is disposed in the apex region where the sheet S is easily subjected to the conveyance load, the conveyance load of the sheet S can be further reduced.

  Details of the guide member 20 will be further described with reference to FIGS. 3 and 4. The guide member 20 further includes a cleaning member 50 and a receiving portion 60. FIGS. 3A and 3B are perspective views showing the guide roller 40, the cleaning member 50, and the receiving portion 60 provided on the guide member 20. 4 is a schematic cross-sectional view taken along the line IV-IV shown in FIG.

  The cleaning member 50 is disposed between the guide roller 30 and the downstream end in the sheet conveyance direction D of the guide surface 30. The cleaning member 50 contacts the peripheral surface of the guide roller 40 and cleans the peripheral surface of the guide roller 40. Therefore, the deposits such as toner and paper dust adhered to the peripheral surface of the guide roller 40 are removed. As a result, it is possible to suppress the contamination of the sheet S due to the deposits. The cleaning member 50 is formed of, for example, a sponge, cotton, or a PET (POLYETHYLENE TEREPHTHALATE) film.

  The receiving portion 60 is formed at a position recessed with respect to the sheet conveyance path P from the guide surface 30 of the guide member 20. That is, the receiving portion 60 is formed at a position farther from the sheet conveyance path P than the cleaning member 50. The receiving part 60 receives deposits removed from the guide roller 40 by the cleaning member 50. Specifically, the receiving part 60 has a receiving surface 61. The receiving surface 61 is positioned below the lowermost part of the peripheral surface of the guide roller 40. Accordingly, the deposit (typically paper dust) removed by the cleaning member 50 falls on the receiving surface 61 and accumulates on the receiving surface 61. As a result, the deposit on the guide roller 40 can be collected, and the deposit can be prevented from diffusing in the apparatus.

[Modification]
With reference to FIGS. 5A and 5B, a fixing device 1 according to a modification of the first embodiment of the present invention will be described. FIG. 5A is a schematic diagram illustrating the first pressing member 33 that presses the guide roller 40. FIG. 5B is a schematic view when the guide roller 40 and the first pressing member 33 are viewed from the direction indicated by the arrow V in FIG. The fixing device 1 according to the modification is different from the fixing device 1 according to the first embodiment in that the guide roller 40 is pressed toward the sheet conveyance path P (see FIG. 1).

  The guide roller 40 is rotatably supported by the shaft 41 and can rotate about the shaft 41. Both ends of the shaft 41 are supported by the guide member 20 so that the shaft 41 and the guide roller 40 can slide in a direction toward the sheet conveyance path P and a direction away from the sheet conveyance path P.

  The fixing device 1 further includes a first pressing member 33, a second pressing member 34, and a support member 35. The first pressing member 33 is a spring having elasticity and formed of a U-shaped metal. The first pressing member 33 may be formed of a wire or may be formed of a sheet metal. The distal end portion of the first pressing member 33 is in contact with the shaft 41, and the proximal end portion of the first pressing member 33 is in contact with the support member 35. The first pressing member 33 is pressed by the second pressing member 34 in a direction toward the sheet conveyance path P (see FIG. 1). As a result, the first pressing member 33 presses the guide roller 40 toward the sheet conveying path P via the shaft 41 with the pressing force Fp.

  According to the modification of the first embodiment, the guide roller 40 is pressed by the first pressing member 33 toward the sheet conveyance path P so as to be slidable. Therefore, when the sheet S having relatively strong tension (waistness) such as thick paper is conveyed, the pressing force Fp can be set so that the guide roller 40 is retracted from the sheet conveyance path P by being pushed by the sheet S. . As a result, when the strongly tensioned sheet S is transported, the gap between the heating roller 11 and the guide member 20 is increased, and the transport load can be reduced even with the strongly tensioned sheet S.

  In addition, since the conveyance load can be reduced even with a strongly tensioned sheet S, the behavior of the strongly tensioned sheet S can be stabilized. Therefore, generation of unfixed toner is suppressed, and the image formed on the sheet S can be prevented from being disturbed. Further, skew can be suppressed even with a sheet S having a strong tension.

  As described above with reference to FIGS. 1 to 5, according to the first embodiment and the modification, the guide roller 40 rotates while being in contact with the sheet S during sheet conveyance, and thus the sheet S to the guide member 20. The frictional resistance due to the contact of is reduced. As a result, the behavior of the sheet S can be regulated while suppressing the conveyance load of the sheet S.

(Embodiment 2)
With reference to FIG. 6, an image forming apparatus 100 according to Embodiment 2 of the present invention will be described. The image forming apparatus 100 is, for example, a copying machine, a printer, or a multifunction machine. The multi-function peripheral includes, for example, at least two devices among a copier, a printer, and a facsimile. Hereinafter, an example in which the image forming apparatus 100 is a printer will be described.

  The image forming apparatus 100 includes a fixing device 1, a feeding unit 110, a transport unit 130, an image forming unit 150, and a discharge unit 190. The fixing device 1 is the fixing device 1 according to the first embodiment or the modification.

  The feeding unit 110 feeds the sheet S to the conveyance unit 130. The feeding unit 110 includes a cassette 111 and a pickup roller 112. The cassette 111 stacks sheets S. The pickup roller 112 takes out the sheet S from the cassette 111 and feeds it to the conveyance unit 130. The sheet S is, for example, plain paper, recycled paper, thin paper, thick paper, coated paper, or an OHP (Overhead Projector) sheet.

  The conveyance unit 130 conveys the sheet S to the image forming unit 150. The conveyance unit 130 includes a registration roller pair 133 and a guide member 70. The registration roller pair 133 performs skew correction of the sheet S fed by the feeding unit 110. Then, the registration roller pair 133 sends the sheet S toward the image forming unit 150 in synchronization with the image formation timing.

  The sheet S sent out by the registration roller pair 133 is conveyed to the image forming unit 150. The image forming unit 150 forms (prints) an image on the sheet S. The image forming unit 150 includes a transfer unit 151, a charging unit 152, an exposure unit 153, a developing unit 154, and a cleaning unit 155. The transfer unit 151 includes a photosensitive drum 151a and a transfer roller 151b.

  The charging unit 152 charges the surface of the photosensitive drum 151a. The exposure unit 153 irradiates the surface of the photosensitive drum 151a with light based on the image data. As a result, an electrostatic latent image corresponding to the image data is formed on the surface of the photosensitive drum 151a. The image data is, for example, image data received from an external device (not shown) via a network (not shown).

  The developing unit 154 attaches toner to the electrostatic latent image and forms a toner image on the surface of the photosensitive drum 151a. The transfer roller 151b transfers the toner image to the sheet S. The cleaning unit 155 removes toner remaining on the surface of the photosensitive drum 151a.

  The sheet S on which the toner image is transferred is guided to the fixing unit 10 by the guide member 70 and the guide member 20. Then, the toner image is fixed on the sheet S by the fixing unit 10.

  The sheet S on which the toner image is fixed is conveyed toward the discharge unit 190. The discharge unit 190 includes a discharge roller pair 191 and a discharge tray 192. The discharge roller pair 191 discharges the sheet S to the discharge tray 192.

  As described above with reference to FIG. 6, according to the second embodiment, the image forming apparatus 100 includes the fixing device 1 according to the first embodiment or the modification. Therefore, as in the first embodiment, the behavior of the sheet can be regulated while reducing the conveyance load of the sheet S. In addition, according to the second embodiment, the same effects as those of the first embodiment or the modification are obtained.

  The embodiments of the present invention have been described above with reference to the drawings. However, the present invention is not limited to the above-described embodiment, and can be implemented in various modes without departing from the gist thereof (for example, (1) to (4) shown below). In order to facilitate understanding, the drawings schematically show each component as a main component, and the thickness, length, number, and the like of each component shown in the drawings are different from the actual for convenience of drawing. . Moreover, the shape, dimension, etc. of each component shown by said embodiment are an example, Comprising: It does not specifically limit, A various change is possible in the range which does not deviate substantially from the effect of this invention.

  (1) Although the curved surface 21 is formed at the downstream end of the guide member 20, the curved surface 21 may not be formed. Further, the guide roller 40 may be disposed at an arbitrary position on the downstream end portion of the guide member 20.

  (2) The cleaning member 50 and the receiving portion 60 can be omitted as appropriate. Further, the cleaning member 50 may be provided without providing the receiving portion 60.

  (3) Although the receiving surface 61 of the receiving portion 60 is a flat surface, the receiving portion 60 can be formed in an arbitrary shape.

  (4) The heating roller 11 described with reference to FIG. 1 is an example of a heating member, and the pressure roller 13 is an example of a pressure member. The heating member may be a belt or a film. The pressure member may be a belt or a film.

  The present invention can be used in the fields of fixing devices and image forming apparatuses.

DESCRIPTION OF SYMBOLS 1 Fixing device 10 Fixing part 20 Guide member 21 Curved surface 30 Guide surface 40 Guide roller 50 Cleaning member 60 Receiving part 150 Image forming part D Sheet conveyance direction P Sheet conveyance path S Sheet S1 Image formation surface S2 Opposite surface

Claims (7)

A fixing unit for fixing the image formed on the sheet to the sheet;
A guide member having a guide surface for guiding the sheet to the fixing unit along a sheet conveyance path,
The guide member is
A rotating member disposed at a downstream end of the guide member in the sheet conveying direction;
A cleaning member for cleaning the peripheral surface of the rotating member;
Receiving the deposit removed from the rotating member by the cleaning member, and
The rotating member protrudes toward the sheet conveying path from the guide surface,
The rotating shaft of the rotating member extends along an orthogonal direction that is a direction orthogonal to the sheet conveying direction,
A curved surface that curves in a convex shape toward the sheet conveying path is formed at the downstream end of the guide member,
The rotating member is disposed in a vertex region of the curved surface;
The receiving portion is disposed in a central region in the orthogonal direction of the guide member so as to face the rotating member,
The fixing unit is
A heating roller for heating the sheet;
A pressure roller for pressing the sheet,
The guide member is a fixing device in which a downstream end portion of the guide member is closer to the heating roller than the pressure roller.   The fixing device according to claim 1, wherein the cleaning member is in contact with a peripheral surface of the rotating member.   The fixing device according to claim 1, wherein the receiving portion is formed at a position recessed with respect to the sheet conveyance path with respect to the guide surface.   4. The fixing device according to claim 1, wherein the guide surface of the guide member is opposed to a surface of the sheet opposite to a surface on which the image is formed. 5. A first pressing member having elasticity;
A second pressing member,
The first pressing member is pressed in the direction toward the sheet conveying path by the second pressing member, and presses the rotating member toward the sheet conveying path by a pressing force,
5. The fixing device according to claim 1, wherein the pressing force is set so that the rotating member is retracted from the sheet conveyance path when pressed by the sheet. 6.   The fixing device according to claim 1, wherein the cleaning member is made of sponge or cotton. A fixing device according to any one of claims 1 to 6,
An image forming apparatus comprising: an image forming unit that forms the image on the sheet.

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