Sheet guide member, fixing device and image forming apparatus

Abstract

To provide a sheet guide member, a fixing device, and an image forming apparatus that can prevent an image defect.SOLUTION: A sheet guide member 6 guides a sheet to which a toner image is transferred along a sheet conveyance direction F, and in a width direction orthogonal to the sheet conveyance direction F, has a width shorter than the width of a sheet with the maximum size allowing the transfer of the toner image. End edge parts 60, 61 in the direction orthogonal to the sheet conveyance direction F extend in a direction away from the sheet.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a sheet guide member, a fixing device, and an image forming apparatus. [Background technology]

[0002] In a conventional image forming apparatus, a toner image is transferred onto a sheet, and the unfixed toner image is fixed onto the sheet at a nip formed between a heating rotor and a pressure rotor. A sheet guide member may be used to guide the sheet along the sheet conveyance direction.

[0003] Known sheet guide members are those that are set to a width smaller than the width of the largest printable sheet, as disclosed in Patent Document 1. By setting the sheet guide member to such a width, it is possible to prevent the sheet guide member from being soiled by toner scattered from the edge of the sheet, particularly during borderless printing (printing without margins). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-7752 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, as a transfer means for transferring a toner image onto a sheet, a voltage of the opposite polarity (for example, positive polarity) to the charge polarity (for example, negative polarity) of the toner image may be applied to a transfer member such as a transfer roller. By applying this voltage, the sheet that has passed through the transfer member becomes charged (for example, positively charged).

[0006] Therefore, when a sheet with a width greater than the width of the sheet guide member passes over the sheet guide member in a charged state, there is a risk that the sheet will discharge to the edge of the sheet guide member in an area of the sheet that is close to the edge of the sheet guide member. The force that attracts the toner image weakens in the discharged area of the sheet, causing the toner image to become distorted due to the discharge, ultimately resulting in image defects. Of course, image defects caused by the above-described toner image distortion are particularly noticeable during borderless printing (printing without margins).

[0007] SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and has as its object to provide a sheet guide member, a fixing device, and an image forming apparatus that can prevent image defects. [Means for solving the problem]

[0008] To achieve the above objectives, The present invention provides a sheet guide member, a fixing device, and an image forming apparatus according to the following first to sixth aspects. (1) Sheet guide member (1-1) First embodiment of sheet guide member Book The first aspect of the invention The sheet guide member is a sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet conveying direction, and has a width in a width direction perpendicular to the sheet conveying direction that is shorter than the width of the sheet of a maximum size onto which the toner image can be transferred, and an edge portion in the direction perpendicular to the sheet conveying direction extends in a direction away from the sheet. An opening is provided in the center in a direction perpendicular to the sheet conveying direction, and the peripheral portion of the opening is recessed in a direction away from the sheet, and the periphery of the opening is formed in an arc shape. It is characterized by the fact that (1-2) Second embodiment of sheet guide member A second aspect of the sheet guide member of the present invention is a sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet transport direction, and is characterized in that, in a width direction perpendicular to the sheet transport direction, it has a width that is shorter than the width of the sheet of the maximum size onto which the toner image can be transferred, and its edge portion in the direction perpendicular to the sheet transport direction extends in a direction away from the sheet, and an opening is provided in the center in the direction perpendicular to the sheet transport direction, and the peripheral portion of the opening extends in a direction away from the sheet, and the peripheral portion of the opening is formed in an arc shape. (1-3) Sheet guide member of the third embodiment A third aspect of the sheet guide member of the present invention is a sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet transport direction, characterized in that an opening is provided in the center in a direction perpendicular to the sheet transport direction, the peripheral portion of the opening is recessed in a direction away from the sheet, and the periphery of the opening is formed in an arc shape. (1-4) Sheet guide member of the fourth aspect A fourth aspect of the sheet guide member of the present invention is a sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet transport direction, and is characterized in that an opening is provided in the center in a direction perpendicular to the sheet transport direction, the peripheral edge of the opening extends in a direction away from the sheet, and the peripheral edge of the opening is formed in an arc shape. (1-5) Sheet guide member of the fifth aspect A fifth aspect of the sheet guide member of the present invention is a sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet transport direction, and is characterized in that in a width direction perpendicular to the sheet transport direction, the width is shorter than the width of the sheet of the maximum size onto which the toner image can be transferred, the edge portion in the direction perpendicular to the sheet transport direction extends in a direction away from the sheet, an opening is provided in the center in the direction perpendicular to the sheet transport direction, the peripheral portion of the opening extends in a direction away from the sheet, and the opening is formed in the shape of a round hole. (1-6) Sixth aspect of the sheet guide member A sixth aspect of the sheet guide member according to the present invention is a sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet transport direction, characterized in that an opening is provided in the center in a direction perpendicular to the sheet transport direction, the peripheral portion of the opening extends in a direction away from the sheet, and the opening is formed in the shape of a round hole.

[0009] In the sheet guide member, the edge portion may extend in a direction away from the sheet over the entire area along the sheet conveying direction.

[0010] The sheet guide member may have an opening at a center portion in a direction perpendicular to the sheet conveying direction, and a periphery of the opening may be recessed in a direction away from the sheet.

[0011] The sheet guide member may have an opening at a center portion in a direction perpendicular to the sheet conveying direction, and a peripheral portion of the opening may extend in a direction away from the sheet.

[0012] Another sheet guide member described in the present application is a sheet guide member that guides a sheet onto which a toner image has been transferred along the sheet transport direction, and is characterized in that an opening is provided in the center in a direction perpendicular to the sheet transport direction, and the peripheral portion of the opening is recessed in a direction away from the sheet.

[0013] Yet another sheet guide member described in the present application is a sheet guide member that guides a sheet onto which a toner image has been transferred along the sheet transport direction, characterized in that an opening is provided in the center in a direction perpendicular to the sheet transport direction, and the peripheral portion of the opening extends in a direction away from the sheet.

[0014] In the sheet guide member, the periphery of the opening may be formed in an arc shape.

[0015] In the sheet guide member, the opening may be formed in the shape of a round hole.

[0016] The fixing device described in the present application comprises the sheet guide member, a heating rotor heated by a heat source, and a pressure rotor abutting the heating rotor, and is characterized in that the sheet guide member guides the sheet to a nip portion formed between the heating rotor and the pressure rotor.

[0017] The image forming apparatus described in the present application is characterized by including both or either one of the sheet guide member and the fixing device. [Effects of the Invention]

[0018] According to the present invention, image defects can be prevented. [Brief explanation of the drawings]

[0019] [Figure 1] 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus according to a first embodiment. [Figure 2] 1 is a schematic cross-sectional view showing a fixing device according to a first embodiment. [Figure 3] 3 is a schematic perspective view of the fixing device of FIG. 2 as viewed from below. FIG. [Figure 4] FIG. 2 is a perspective view showing a sheet guide member in the first embodiment. [Figure 5] 5 is a plan view of the sheet guide member of FIG. 4 as viewed from the sheet side. [Figure 6] 6 is a cross-sectional view taken along the line AA of the sheet guide member of FIG. 5. [Figure 7] FIG. 10 is a perspective view showing a sheet guide member in the second embodiment. [Figure 8] 8 is a plan view of the sheet guide member of FIG. 7 as viewed from the sheet side. [Figure 9] 9 is a cross-sectional view of the sheet guide member of FIG. 8 taken along line BB. DETAILED DESCRIPTION OF THE INVENTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. Note that the same components in the embodiments described below will be designated by the same reference numerals, and redundant descriptions of those components will be omitted.

[0021] (Embodiment 1) -Overall configuration of image forming device- First, the overall configuration of the image forming apparatus A in the first embodiment will be described.

[0022] FIG. 1 is a schematic cross-sectional view showing the configuration of an image forming apparatus A in embodiment 1. In the figure, the symbol X indicates the width direction (depth direction), with the -X direction (negative X direction) being the front direction and the +X direction (positive X direction) being the rear direction. The symbol Y indicates the left-right direction perpendicular to the width direction X, with the -Y direction (negative Y direction) being the left direction and the +Y direction (positive Y direction) being the right direction. The symbol Z indicates the up-down direction, with the -Z direction (negative Z direction) being the down direction and the +Z direction (positive Z direction) being the up direction. These settings are the same in the following embodiments.

[0023] Image forming apparatus A is an electrophotographic image forming apparatus and an intermediate transfer color multifunction machine capable of printing full-color images. Image forming apparatus A has an image reading unit 1, an image forming unit 2, a transfer body 3, a secondary transfer unit 4, a fixing device 5, a sheet storage unit 8, a sheet roller group 9, and a sheet discharge unit 90 (see FIG. 1). Image forming apparatus A is provided with a sheet transport path S along which sheets are transported. In this embodiment, toners of yellow (Y), magenta (M), cyan (C), and black (K) are used for printing by image forming apparatus A.

[0024] The image reading unit 1 reads an image from a document and is provided on top of the image forming apparatus A. The image reading unit 1 has a document reading device 10, a document placing table 11, and an automatic document processing device 12 (see FIG. 1).

[0025] The document reading device 10 irradiates a document with light and reads an image from the document based on the reflected light. The document reading device 10 includes, for example, a light source that irradiates the document with light, a lens, an image sensor, and a mirror that guides the reflected light from the document to the lens. The reflected light from the document is incident on the image sensor via the lens and is photoelectrically converted by the image sensor to generate image data.

[0026] The document table 11 is a portion on which a user places a document, and is provided above the document reading device 10 (see FIG. 1). The document table 11 is made of transparent glass. The automatic document processing device 12 is provided above the document table 11 (see FIG. 1), and automatically and continuously transports documents inserted by a user to the document reading device 10. An image of the document is read by the document reading device 10 while the document is placed on the document table 11 or while the document is transported to the document reading device 10 by the automatic document processing device 12.

[0027] The image forming unit 2 forms a toner image based on image data, and includes an exposure device 20, a developing device 21, an image carrier 22, a charging device 23, and a cleaning unit 24 (see FIG. 1). The image data may be generated by the image reading unit 1 or may be supplied from an external device.

[0028] The exposure device 20 exposes the surface of the image carrier 22, which has been charged by the charging device 23, to light corresponding to each color, thereby forming an electrostatic latent image corresponding to each color on the image carrier 22. The exposure device 20 incorporates a light source (not shown), a polygon mirror 200 that scans the laser beam emitted from the light source, and optical elements (for example, a lens 201, a mirror 202, etc.) that guide the laser light reflected by the polygon mirror 200 to the image carrier 22.

[0029] The developing device 21 forms a toner image by developing (visualizing) the electrostatic latent image formed on the surface of each image carrier 22 with toner of each color (Y, M, C, K) supplied from the toner cartridge T. The developing device 21 has a developer carrier 25 that causes toner to fly onto the surface of the image carrier 22. When a high-voltage development bias is applied to the developer carrier 25, the toner flies to the image carrier 22 and is supplied to the electrostatic latent image formed on the surface of the image carrier 22, thereby forming a toner image on the surface of the image carrier 22.

[0030] The image carrier 22, on whose surface an electrostatic latent image is formed, is rotated in a predetermined direction by a main motor (not shown). As the image carrier 22 is rotated, the toner image visualized on the image carrier 22 is transported to the transfer body 3.

[0031] The charging device 23 applies a high-voltage charging bias to uniformly charge the surface of the image carrier 22 to a predetermined potential. The charging device 23 may be, for example, a contact-type charger (e.g., a roller-type or brush-type charger) or a charger-type charger.

[0032] The cleaning unit 24 removes and collects toner remaining on the surface of the image carrier 22 after development and image transfer.

[0033] The transfer body 3 is disposed above the image carrier 22, and the toner images of each color formed on the surface of the image carrier 22 are temporarily transferred onto the transfer body 3. The transfer body 3 has an intermediate transfer belt 30, a drive roller 31, a driven roller 32, and a primary transfer section 33.

[0034] The intermediate transfer belt 30 is an endless belt that rotates in a predetermined direction and is suspended between a drive roller 31 and a driven roller 32. The outer surface of the intermediate transfer belt 30 is in contact with the image carrier 22. The toner images of each color visualized on the image carrier 22 are transferred onto the intermediate transfer belt 30 in order, superimposed on top of each other. The toner images transferred onto the intermediate transfer belt 30 are transported to the secondary transfer unit 4 by the rotation of the intermediate transfer belt 30. The intermediate transfer belt 30 is formed, for example, from a film having a thickness of about 100 μm to 150 μm.

[0035] The drive roller 31 is a roller that is driven to rotate in a predetermined direction by the driving of a belt motor (not shown), and is provided on the right end side of the transfer body 3 (see FIG. 1). The rotation of the drive roller 31 causes the intermediate transfer belt 30 to rotate.

[0036] The driven roller 32 is a roller that is rotatably provided along the intermediate transfer belt 30 (see FIG. 1). The driven roller 32 is rotated in accordance with the rotation of the intermediate transfer belt 30.

[0037] The primary transfer unit 33 transfers the toner image onto the transfer body 3, and is, for example, a transfer roller, and is provided so as to face the image carrier 22 via the intermediate transfer belt 30 (see FIG. 1). A high-voltage transfer bias is applied to the primary transfer unit 33, so that the toner image on the image carrier 22 is transferred onto the intermediate transfer belt 30.

[0038] A conductive elastic material (made of a material such as EPDM or urethane foam) is provided on the outer peripheral surface of the primary transfer unit 33. The provision of this conductive elastic material makes it possible to apply a uniform high voltage to the intermediate transfer belt 30. Hereinafter, the transfer of the toner images of each color formed on the image carrier 22 onto the intermediate transfer belt 30 will be referred to as "primary transfer."

[0039] The secondary transfer unit 4 transfers the toner images of each color that have been primarily transferred onto the intermediate transfer belt 30 onto a sheet. The secondary transfer unit 4 has a secondary transfer roller 40 provided at a transfer location where the sheet and the intermediate transfer belt 30 face each other. A voltage for transferring the toner images of each color on the intermediate transfer belt 30 onto the sheet, i.e., a voltage of opposite polarity (e.g., positive polarity) to the charge polarity (e.g., negative polarity) of the toner, is applied to the secondary transfer roller 40. Hereinafter, the transfer of the toner images of each color that have been transferred onto the intermediate transfer belt 30 onto the sheet will be referred to as "secondary transfer."

[0040] The fixing device 5 fixes the toner image onto the sheet by heating and melting the toner image that has been secondarily transferred onto the sheet and fixing it to the sheet, and is located downstream of the secondary transfer section 4 in the sheet conveying path S.

[0041] The sheet storage unit 8 is disposed at the bottom of the image forming apparatus A and has a cassette 80 that stores sheets to be used for image formation. The sheet storage unit 8 may have a plurality of cassettes 80. Furthermore, each of the plurality of cassettes 80 may store sheets of any material or size.

[0042] The sheet roller group 9 includes a pickup roller 9a, conveyance rollers 9b to 9d, and a registration roller 9e.

[0043] The pickup roller 9a pulls out the topmost recording paper (sheet) from the stack of sheets stored in the sheet storage unit 8 and transports it to the sheet transport path S. The transport rollers 9b to 9d transport the sheet along the sheet transport path S. The registration roller 9e temporarily stops the sheet being transported from the sheet storage unit 8 and aligns the leading edge of the sheet. Each of these sheet rollers 9 is rotated by a motor (not shown).

[0044] The sheet discharge section 90 is provided on the top of the image forming apparatus A, and is used to load and pull out printed sheets face down.

[0045] In addition to the above configuration, the image forming apparatus A is provided with a control unit (not shown) that controls the above-described components in response to input operations by the user.

[0046] The image forming apparatus A described above prints on a sheet as follows. First, the image forming unit 2 forms a toner image based on image data generated by the image reading unit 1 or supplied from an external device. This toner image is primarily transferred onto the intermediate transfer belt 30 of the transfer body 3. During this time, the sheet is pulled out of the sheet storage unit 8 by the pickup roller 9a, transported to the registration rollers 9e by the transport rollers 9b, and then transported to the secondary transfer unit 4 by the registration rollers 9e. Next, the secondary transfer unit 4 secondarily transfers the toner image primarily transferred onto the intermediate transfer belt 30 onto the sheet. The fixing device 5 fixes the toner image secondarily transferred onto the sheet. The sheet is then transported by the transport rollers 9d and discharged onto the sheet discharge unit 90, completing the printing on the sheet.

[0047] -Fixing device- Fig. 2 is a schematic cross-sectional view showing the fixing device 5 in embodiment 1. Fig. 3 is a schematic perspective view of the fixing device 5 as seen from below. In Fig. 3, the fastening member B at the center of the sheet guide member 6 is not shown.

[0048] The fixing device 5 includes a heating rotor 50, a pressure rotor 51, a frame 52, a sheet guide member 6, and a sheet sensor 7. Each component of the fixing device 5 will be described in detail below.

[0049] In this embodiment, the heating rotator 50 includes a fixing roller 500, a heating roller 501, a heat source 502, and a fixing belt 503 (see FIG. 2).

[0050] The fixing roller 500 is supported by a frame 52 so as to be rotatable in the direction of its rotation axis along the X direction. The heating roller 501 has a built-in heat source 502. The heat source 502 is formed of, for example, a lamp heater such as a halogen lamp. The fixing belt 503 is an endless belt that is suspended between the fixing roller 500 and the heating roller 501 and is rotatable in the direction of its rotation axis along the X direction, and has a predetermined width along the X direction. The fixing belt 503 is heated to a predetermined temperature (fixing temperature) by the heat source 502 via the heating roller 501. In this embodiment, the fixing belt 503 is rotated in accordance with the rotation of the pressure rotor 51.

[0051] The pressure rotator 51 abuts against the outer side of the fixing belt 503 facing the fixing roller 500 of the heating rotator 50, and is supported by a frame 52 so as to be rotatable in the direction of its rotation axis along the X direction. The pressure rotator 51 is driven to rotate by a drive unit (not shown). The pressure rotator 51 is also biased toward the fixing belt 503 by a biasing member (not shown). A nip FN, through which a sheet can pass, is formed between the pressure rotator 51 and the heating rotator 50 along the X direction. A sheet of the maximum size that can be passed through the image forming apparatus A (e.g., A3 size in the longitudinal feed direction or A4 size in the transverse feed direction) can pass through the nip FN. The pressure rotator 51 and the heating rotator 50 are configured to melt unfixed toner on the sheet by heat at the nip FN and nip the sheet to convey it.

[0052] The frame 52 is formed of a metal material such as a galvanized steel plate. An inlet 53 is formed in the frame 52 on the upstream side of the nip portion FN in the sheet conveying direction F, and an outlet 54 is formed on the downstream side of the nip portion FN in the sheet conveying direction F (see FIG. 2).

[0053] Fig. 4 is a perspective view showing the sheet guide member 6 in embodiment 1. Fig. 5 is a plan view of the sheet guide member 6 in Fig. 4 as seen from the sheet side. Fig. 6 is a cross-sectional view of the sheet guide member 6 in Fig. 5 taken along line AA.

[0054] The sheet guide member 6 guides the sheet having the toner image transferred thereon along the sheet conveying direction F, and is fixed to the frame 52 at an inlet 53 with fastening members B such as screws (see FIG. 3). In this embodiment, the sheet guide member 6 guides the sheet to the nip portion FN. The sheet guide member 6 is formed of a metal material such as a stainless steel plate. In the width direction (the X direction in this embodiment) perpendicular to the sheet conveying direction F, the sheet guide member 6 has a width that is shorter than the width of the largest size sheet onto which a toner image can be transferred (for example, A3 size in the longitudinal feed direction or A4 size in the transverse feed direction).

[0055] In this embodiment, edge portions 60, 61 (edge portion 60 on the -X direction side and edge portion 61 on the +X direction side) of the sheet guide member 6 in the direction (X direction) perpendicular to the sheet conveying direction F are extended in a direction away from the sheet (see FIGS. 4 and 6). The extension amount of the edge portions 60, 61 is, for example, about 2 to 3 mm.

[0056] The edge portions 60 and 61 are extended in a direction away from the sheet, which has the effect of preventing image defects.

[0057] The sheet passes through the secondary transfer unit 4 and then passes through the sheet guide member 6. That is, the sheet passing through the sheet guide member 6 becomes charged (positively charged in this embodiment) due to the voltage applied during the secondary transfer. Here, if the sheet has a width greater than the width of the sheet guide member 6 in the direction (X direction) perpendicular to the sheet conveying direction F, the charged sheet approaches the edge portions 60, 61 of the sheet guide member 6.

[0058] If the edges 60, 61 were not extended away from the sheet, the distance between the sheet and the edges 60, 61 might be small enough to cause the sheet to discharge to the edges 60, 61. High-resistivity sheets, such as cardboard and coated paper, may become excessively charged during secondary transfer, making the sheet more susceptible to discharge to the edges 60, 61. If discharge occurs to the edges 60, 61 as the sheet passes through the sheet guide member 6, the charge disturbance will disturb the unfixed toner image on the sheet. In particular, in the case of borderless printing (printing without margins), the toner image at the side edges of the sheet will be disturbed. This disturbance in the toner image can cause image defects.

[0059] As described above, by extending the edge portions 60, 61 in a direction away from the sheet, a sufficient distance is secured between the sheet and the edge portions 60, 61 to prevent discharge of the sheet to the edge portions 60, 61. Therefore, even if a high-resistivity sheet passes through the sheet guide member 6, discharge of the sheet is prevented, and disturbance of the toner image due to discharge of the sheet is prevented. This makes it possible to prevent image defects.

[0060] In this embodiment, the edge portions 60, 61 extend in a direction away from the sheet over the entire area along the sheet conveying direction F (see FIG. 4). This ensures a sufficient distance between the sheet and the edge portions 60, 61 over the entire area along the sheet conveying direction F to prevent discharge of the sheet to the edge portions 60, 61, thereby reliably preventing discharge of the sheet.

[0061] In this embodiment, an opening 62 having a substantially home plate shape is provided in the center of the sheet guide member 6 in the direction (X direction) perpendicular to the sheet conveying direction F (see FIGS. 3 to 6). A sheet sensor 7 is attached to the opening 62 (see FIG. 2).

[0062] The sheet sensor 7 is a sensor that faces the opening 62 of the sheet guide member 6 and detects the passage of a sheet in a non-contact manner, and is configured, for example, by a reflective photosensor.

[0063] In this embodiment, a peripheral portion 63 of the opening 62 in the sheet guide member 6 is recessed in a direction away from the sheet (see FIGS. 5 and 6). The recessed amount of the peripheral portion 63 is, for example, about 2 to 3 mm.

[0064] The peripheral portion 63 of the opening 62 in the sheet guide member 6 is recessed in a direction away from the sheet, which has the effect of preventing image defects. Specifically, this is as follows.

[0065] Depending on the distance between the sheet and the peripheral edge 62a of the opening 62, there is a risk of discharge of the sheet to the peripheral edge 62a of the opening 62. Discharge of the sheet to the peripheral edge 62a of the opening 62 is similar to the discharge of the sheet to the above-mentioned edge portions 60 and 61, but differs in that discharge of the sheet can occur regardless of the width of the sheet relative to the width of the sheet guide member 6.

[0066] As described above, the peripheral portion 63 of the opening 62 in the sheet guide member 6 is recessed in a direction away from the sheet, so that a sufficient distance is secured between the sheet and the peripheral edge 62a of the opening 62 to prevent discharge of the sheet to the peripheral edge 62a of the opening 62. This prevents discharge of the sheet and prevents disturbance of the toner image due to discharge of the sheet. This makes it possible to prevent image defects.

[0067] The fixing device 5 described above is of a so-called belt fixing type, but is not limited to this. The fixing device 5 may be configured so that the pressure rotor 51 directly presses the fixing roller 500.

[0068] Furthermore, the shape and extension amount of the edge portions 60, 61 described above are examples, and the key point is that it is sufficient to ensure a distance between the sheet and the edge portions 60, 61 sufficient to prevent discharge of the sheet to the edge portions 60, 61.

[0069] Furthermore, the amount of recession of the peripheral portion 63 of the opening 62 described above is an example, and the key point is that it is sufficient to ensure a distance between the sheet and the peripheral portion 62a of the opening 62 that is sufficient to prevent discharge of the sheet to the peripheral portion 62a of the opening 62.

[0070] Furthermore, the shape of the opening 62 is an example, and for example, the periphery of the opening 62 may be formed in an arc shape. When the periphery of the opening 62 is formed in an arc shape, local concentration of electric charge at the periphery 62a of the opening 62 is avoided, and discharge of the sheet to the periphery 62a of the opening 62 can be efficiently suppressed.

[0071] (Embodiment 2) Hereinafter, only the differences between the second embodiment and the first embodiment will be described.

[0072] Fig. 7 is a perspective view showing a sheet guide member 6 in embodiment 2. Fig. 8 is a plan view of the sheet guide member 6 in Fig. 7 as seen from the sheet side. Fig. 9 is a BB cross-sectional view of the sheet guide member 6 in Fig. 8.

[0073] In the second embodiment, a round hole-shaped opening 64 is provided in the center of the sheet guide member 6 in the direction (X direction) perpendicular to the sheet conveying direction F (see FIGS. 7 to 9). A peripheral edge 64a of the opening 64 extends in a direction away from the sheet (see FIGS. 7 and 9). The extension amount of the peripheral edge 64a is, for example, about 2 to 3 mm.

[0074] By extending the peripheral edge 64a of the opening 64 in a direction away from the sheet, a sufficient distance is secured between the sheet and the peripheral edge 64a of the opening 64 to prevent discharge of the sheet to the peripheral edge 64a of the opening 64. This prevents discharge of the sheet and prevents disturbance of the toner image due to discharge of the sheet. This makes it possible to prevent image defects.

[0075] In addition, in embodiment 2, since the periphery of the opening 64 is formed in an arc shape, local concentration of electric charge at the periphery 64a of the opening 64 is avoided, and discharge of the sheet to the periphery 64a of the opening 64 can be efficiently suppressed.

[0076] Furthermore, by forming the opening 64 in a circular hole shape, it is possible to form the peripheral edge 64a of the opening 64 in a shape that is extended in a direction away from the sheet, for example, by using burring. In other words, it is possible to easily ensure a distance between the sheet and the peripheral edge 64a of the opening 64 that is sufficient to prevent discharge of the sheet to the peripheral edge 64a of the opening 64.

[0077] In the embodiment described above, the sheet guide member 6 guides the sheet to the nip portion FN in the fixing device 5, but the sheet guide member 6 may be any member that guides the sheet onto which the toner image has been transferred along the sheet conveying direction F, and may be applied to the sheet conveying path S after the step of transferring the toner onto the sheet and up to the fixing step. For example, the sheet guide member 6 may be applied as a guide member that guides the sheet to the nip portion of the transfer roller (in this example, the secondary transfer unit 4).

[0078] The above-described embodiments and examples are illustrative in all respects and are not intended to be limiting. Therefore, the technical scope of the present invention should not be interpreted solely by the above-described embodiments and examples, but should be defined based on the claims. Furthermore, all modifications within the meaning and scope of the claims are included. [Explanation of symbols]

[0079] A Image forming device 5 Fixing device 50 Heating Rotor 500 Fuser roller 501 Heating roller 502 Heat source 503 Fixing belt 51 Pressurized Rotating Body 52 frames 6 Sheet guide member 60,61 Edge 62 Opening 62a Periphery 63 Periphery 64 Opening 64a Periphery 7 Sheet Sensor F Conveying direction FN nip section

Claims

1. A sheet guide member that guides a sheet on which a toner image has been transferred along a sheet conveying direction, the width of the sheet is set to be shorter than the width of the sheet having a maximum size onto which the toner image can be transferred in a width direction perpendicular to the sheet conveying direction, an edge portion in a direction perpendicular to the sheet conveying direction extends in a direction away from the sheet, an opening is provided at a center portion in a direction perpendicular to the sheet conveying direction, The peripheral portion of the opening is recessed in a direction away from the sheet, A sheet guide member, wherein the periphery of the opening is formed in an arc shape.

2. A sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet conveying direction, the width of the sheet is set to be shorter than the width of the sheet having a maximum size onto which the toner image can be transferred in a width direction perpendicular to the sheet conveying direction, an edge portion in a direction perpendicular to the sheet conveying direction extends in a direction away from the sheet, an opening is provided at a center portion in a direction perpendicular to the sheet conveying direction, The peripheral edge of the opening extends in a direction away from the sheet, A sheet guide member, wherein the periphery of the opening is formed in an arc shape.

3. A sheet guide member that guides a sheet on which a toner image has been transferred along a sheet conveying direction, an opening is provided at a center portion in a direction perpendicular to the sheet conveying direction, The peripheral portion of the opening is recessed in a direction away from the sheet, A sheet guide member, wherein the periphery of the opening is formed in an arc shape.

4. A sheet guide member that guides a sheet on which a toner image has been transferred along a sheet conveying direction, an opening is provided at a center portion in a direction perpendicular to the sheet conveying direction, The peripheral edge of the opening extends in a direction away from the sheet, A sheet guide member, wherein the periphery of the opening is formed in an arc shape.

5. A sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet conveying direction, the width of the sheet is set to be shorter than the width of the sheet having a maximum size onto which the toner image can be transferred in a width direction perpendicular to the sheet conveying direction, an edge portion in a direction perpendicular to the sheet conveying direction extends in a direction away from the sheet, an opening is provided at a center portion in a direction perpendicular to the sheet conveying direction, The peripheral edge of the opening extends in a direction away from the sheet, The sheet guide member is characterized in that the opening is formed in a round hole shape.

6. A sheet guide member that guides a sheet onto which a toner image has been transferred along a sheet conveying direction, an opening is provided at a center portion in a direction perpendicular to the sheet conveying direction, The peripheral edge of the opening extends in a direction away from the sheet, The sheet guide member is characterized in that the opening is formed in a round hole shape.

7. 6. The sheet guide member according to claim 1, claim 2 or claim 5, The sheet guide member is characterized in that the edge portion extends in a direction away from the sheet over the entire area along the sheet conveying direction.

8. 5. The sheet guide member according to claim 2 or 4, The sheet guide member is characterized in that the opening is formed in a round hole shape.

9. a sheet guide member according to any one of claims 1 to 8; a heating rotor that is heated by a heat source; a pressure rotating body that contacts the heating rotating body, a sheet guide member for guiding the sheet to a nip portion formed between the heating rotary member and the pressure rotary member;

10. 10. An image forming apparatus comprising: a sheet guide member according to claim 1; and / or a fixing device according to claim 9.

Images