Conveyance device and image forming device

Abstract

To provide a conveyance device and an image forming device capable of preventing dew condensation by suppressing the temperature increase of circumambient air after fixing even when a fixing temperature is increased and preventing a transfer failure during two-sided printing.SOLUTION: This conveyance device for conveying a recording medium on which an image is fixed by a fixing unit comprises a first guide for conveying the recording medium on the downstream side of the fixing unit. The first guide is provided with a sheet metal and a resin sheet provided in the conveyance surface of the sheet metal. A sheet higher in thermal conductivity than the sheet metal is provided between the sheet metal and the resin sheet.SELECTED DRAWING: Figure 3A

Description

[Technical Field]

[0001] The present invention relates to a conveying device and an image forming apparatus, and more particularly to a conveying device and the like that can prevent condensation by suppressing the temperature rise of the surrounding air after fixing even when the fixing temperature is increased, thereby preventing transfer failure during double-sided printing. [Background technology]

[0002] Generally, in electrophotographic image forming devices such as copiers and printers, a toner image formed on an image carrier is transferred to a recording medium, and the transferred toner image is fixed by a fixing device to form an image. For example, one fixing device passes the recording medium between a heating roller and a pressure roller, and heats and presses the recording medium at the nip between them. In such an image forming apparatus, a transport path is formed to properly transport the recording medium. For example, a transport device is used that properly guides the recording medium onto which the toner image has been transferred to the nip of the fixing device and transports the recording medium after the toner image has been fixed.

[0003] After fixing, the recording medium, paper, is hot, so as it passes through the transport path of the transport device, the temperature of the transport guide plate rises. After the paper passes through the transport path, the heat from the transport guide plate is transferred to the air around the transport guide plate, raising the temperature of the air, while the transport guide plate loses heat from its surroundings. This creates a temperature difference between the transport guide plate and the air, causing condensation to form on the surface of the transport guide plate. This condensation can then adhere to the next sheet of paper being transported, resulting in poor transfer during double-sided printing.

[0004] Therefore, in order to moderate the temperature change of the transport guide plate, for example, Patent Document 1 discloses a technique in which a member made of high-density polyethylene with low thermal conductivity is attached to the surface of the transport guide plate. However, when the fixing temperature is increased to improve image fixation, the paper temperature rises, causing condensation to form between the air and the guide plate, which is made of high-density polyethylene with low thermal conductivity, resulting in poor transfer. In addition to attaching a member made of high-density polyethylene with low thermal conductivity to prevent condensation, there are other methods, such as providing a cooling fan to lower the temperature of the paper. Another method is to increase the thickness of the member with low thermal conductivity to moderate heat conduction. However, these methods are difficult to adopt due to space constraints. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 2934532 Summary of the Invention [Problem to be solved by the invention]

[0006] The present invention has been made in consideration of the above problems and circumstances. The problem to be solved by the present invention is to provide a conveying device and an image forming apparatus that can prevent condensation by suppressing the temperature rise of the surrounding air after fixing, even if the fixing temperature is increased, and can prevent transfer failures during double-sided printing. [Means for solving the problem]

[0007] The inventors investigated the causes of the above problems in order to solve them. They discovered that the first guide, which transports the recording medium downstream of the fixing unit, is configured to include, from the transport surface side, a resin sheet, a sheet with a higher thermal conductivity than the metal sheet, and a metal sheet, in that order. They discovered that this makes it possible to prevent condensation on the transport surface when transporting paper after fixing. That is, the above-mentioned problems of the present invention are solved by the following means.

[0008] 1. A conveying device that conveys a recording medium on which an image has been fixed in a fixing unit, a first guide for conveying the recording medium downstream of the fixing unit; The first guide includes a metal plate and a resin sheet provided on a conveying surface of the metal plate, A sheet having a higher thermal conductivity than the metal plate is provided between the metal plate and the resin sheet. A conveying device characterized by:

[0009] 2. The sheet with high thermal conductivity is provided facing the non-image side of the recording medium via the resin sheet. 2. The conveying device according to claim 1,

[0010] 3. A second guide is provided upstream of the first guide and downstream of the fixing portion, The second guide is made of a material having a lower thermal conductivity than sheet metal. 2. The conveying device according to claim 1,

[0011] 4. A third guide is provided downstream of the first guide, the third guide is formed of sheet metal, The metal plate comes into direct contact with the non-image surface of the recording medium. 2. The conveying device according to claim 1,

[0012] 5. The sheet with high thermal conductivity is thinner than the metal plate and the resin sheet of the first guide. 2. The conveying device according to claim 1,

[0013] 6. The thickness of the sheet with high thermal conductivity is less than 0.1 mm 6. The conveying device according to claim 5,

[0014] 7. The material of the sheet with high thermal conductivity is aluminum. 2. The conveying device according to claim 1,

[0015] 8. The material of the resin sheet is high-density polyethylene. 2. The conveying device according to claim 1,

[0016] 9. The sheet with high thermal conductivity is provided on the entire surface of the resin sheet opposite to the conveying surface. 2. The conveying device according to claim 1,

[0017] 10. The resin sheet and the sheet with high thermal conductivity cover the entire width of the recording medium. 2. The conveying device according to claim 1,

[0018] 11. The resin sheet and the sheet with high thermal conductivity are provided in separate sections in the width direction of the recording medium. 2. The conveying device according to claim 1,

[0019] 12. A recording medium conveying apparatus including an image forming unit that forms an image on a recording medium, a fixing unit that fixes the image on the recording medium, and the conveying device according to any one of items 1 to 11 that conveys the recording medium on which the image has been fixed. An image forming apparatus characterized by: [Effects of the Invention]

[0020] The above-described means of the present invention can provide a conveying device and an image forming apparatus that can prevent condensation by suppressing the temperature rise of the surrounding air after fixing, even if the fixing temperature is increased, and can prevent transfer failure during double-sided printing. The mechanism by which the effects of the present invention are manifested or the mechanism of action is not clear, but is speculated as follows. First, the mechanism by which condensation occurs will be described. 1A and 1B are cross-sectional schematic diagrams of a guide that transports a recording medium (paper S) and paper S when the guide is made of a metal plate 113. FIG. 1A shows the state of the guide while paper S is passing, and FIG. 1B shows the state of the guide after paper S has passed. As shown in Fig. 1A, when the hot paper S after fixing comes into contact with the low-temperature metal plate 113, the temperature of the surface 113a of the metal plate 113 and the surrounding air G rises after the paper passes, as shown in Fig. 1B. At this time, heat is rapidly absorbed from the surface 113a of the metal plate 113, creating a temperature difference between the cooled metal plate 113 and the warmed air G. As a result, condensation W forms on the surface 113a of the metal plate 113.

[0021] 2 is a cross-sectional view of the guide and the paper S when a resin sheet 114 with a lower thermal conductivity than the metal plate 113 is provided on the conveying surface of the guide that conveys the paper S. Also, FIG. 2 shows the state of the guide after the paper S has passed through. 1A, by providing a resin sheet 114 with low thermal conductivity on the metal plate 113 as shown in Fig. 2, it is possible to suppress sudden temperature changes, which is more effective than when the guide is made of metal plate 113 as shown in Fig. 1A. This slows down the rate at which heat is absorbed by the metal plate 113, making it less likely that condensation will occur. However, if the fixing temperature is further increased to improve the fixability of the image, the temperature of the paper S also rises further, and this cannot be addressed by simply providing a resin sheet 114 with low thermal conductivity to slow down the rate at which heat is absorbed by the metal plate 113. As a result, the temperatures of the surface 114a of the resin sheet 114 and the surrounding air G rise, creating a temperature difference between the cooled metal plate 113 and the warmed air G, resulting in condensation W.

[0022] Therefore, in the present invention, as shown in Fig. 3A, a sheet 115 with high thermal conductivity is provided between a metal plate 113 and a resin sheet 114 with low thermal conductivity. Figs. 3A and 3B are cross-sectional schematic diagrams of a first guide 111A and a sheet of paper S according to the present invention. Fig. 3A shows the state of first guide 111A while the sheet of paper S is passing, and Fig. 3B shows the state of first guide 111A after the sheet of paper S has passed. As in the present invention, first guide 111A is configured with, from the conveyance side, resin sheet 114, highly thermally conductive sheet 115, and metal plate 113. As shown in FIG. 3A, even if the surrounding air G is heated by high-temperature paper S, highly thermally conductive sheet 115 dissipates the heat to the surroundings. Therefore, as shown in FIG. 3B, after paper S passes through, the temperature rise of resin sheet 114 itself is suppressed, and the temperature rise of air G heated by resin sheet 114 is also suppressed. By suppressing the temperature rise of air G, when resin sheet 114 is cooled by metal plate 113, a temperature difference is unlikely to occur between resin sheet 114 and air G, preventing condensation. As a result, transfer failures due to condensation can be prevented during double-sided printing. [Brief explanation of the drawings]

[0023] [Figure 1A] Schematic cross-sectional view of the guide and paper when the guide is made of sheet metal [Figure 1B] Schematic cross-sectional view of the guide and paper when the guide is made of sheet metal [Figure 2] Schematic cross-sectional view of the recording medium and paper when a resin sheet with lower thermal conductivity than the metal plate is installed on the conveying surface of the guide. [Figure 3A] Schematic cross-sectional view of a first guide and paper according to the present invention [Figure 3B] Schematic cross-sectional view of a first guide and paper according to the present invention [Figure 4] 1 is a schematic diagram showing the configuration of a conveying device according to the present invention; [Figure 5] Schematic cross-sectional view of a second guide and paper according to the present invention. [Figure 6] Schematic cross-sectional view of a third guide and paper according to the present invention [Figure 7] 1 is a schematic diagram illustrating a configuration of an image forming apparatus according to the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0024] The conveying device of the present invention is a conveying device that conveys a recording medium on which an image has been fixed in a fixing section, and is characterized in that it has a first guide that conveys the recording medium downstream of the fixing section, the first guide comprising a metal plate and a resin sheet provided on the conveying surface of the metal plate, and a sheet with a higher thermal conductivity than the metal plate is provided between the metal plate and the resin sheet. This feature is a technical feature common to or corresponding to each of the following embodiments.

[0025] In one embodiment of the present invention, the sheet with high thermal conductivity is preferably disposed opposite the non-image side of the recording medium via the resin sheet, thereby preventing the effects of condensation on the non-image side of the recording medium to be printed during double-sided printing, and reliably preventing transfer defects.

[0026] It is preferable that a second guide is provided upstream of the first guide and downstream of the fixing unit, and that the second guide is made of a material with lower thermal conductivity than sheet metal, thereby reliably preventing condensation on the second guide, which is the first to come into contact with the paper heated by fixing.

[0027] It is preferable that a third guide be provided downstream of the first guide, the third guide be formed of sheet metal, and the sheet metal be in direct contact with the non-image side of the recording medium. Because the paper gradually cools as it is transported downstream, condensation is less likely to occur in the third guide. Therefore, sheet metal can be used in the third guide, which is less likely to cause condensation, thereby reducing costs and enabling the third guide to be manufactured with high precision.

[0028] It is preferable that the high thermal conductivity sheet is thinner than the metal plate and the resin sheet of the first guide. In particular, it is preferable that the high thermal conductivity sheet is thinner than 0.1 mm. This prevents the recording medium transport path from becoming narrow, allowing for smooth transport. Furthermore, since the purpose of the high thermal conductivity sheet is to disperse heat from the resin sheet, it can still fully fulfill its function even if it is thin.

[0029] The material of the sheet having high thermal conductivity is preferably aluminum, since it can be easily processed into a thin sheet.

[0030] The material of the resin sheet is preferably high-density polyethylene in terms of durability and thermal conductivity.

[0031] It is preferable that the sheet having high thermal conductivity is provided on the entire surface of the resin sheet opposite to the conveying surface, in order to reliably prevent condensation.

[0032] It is preferable that the resin sheet and the sheet with high thermal conductivity cover the entire width of the recording medium. By covering the entire width of the recording medium with the resin sheet and the sheet with high thermal conductivity, there is no direct contact between the metal plate and the recording medium, and condensation can be reliably prevented.

[0033] It is preferable that the resin sheet and the sheet with high thermal conductivity are provided separately in the width direction of the recording medium, which facilitates the assembly work when the resin sheet and the sheet with high thermal conductivity are provided on the metal plate.

[0034] The image forming apparatus of the present invention is characterized by comprising an image forming unit that forms an image on a recording medium, a fixing unit that fixes the image to the recording medium, and a conveying device that conveys the recording medium with the fixed image. This makes it possible to prevent condensation in the conveying device by suppressing the rise in the ambient air temperature after fixing, even if the fixing temperature is increased. As a result, transfer failures during double-sided printing can be prevented.

[0035] The present invention, its components, and embodiments and modes for carrying out the present invention will be described below. In this application, the symbol "to" is used to mean that the numerical values ​​before and after it are included as lower and upper limits.

[0036] [Transportation equipment] FIG. 4 is a schematic diagram showing the configuration of the transport device. The conveying device 100 is a device that conveys a recording medium on which an image has been fixed by the fixing unit 60. It is preferable that the conveying device 100 is a device that conveys a recording medium after an image has been formed and fixed on the front surface thereof, so that an image can be further formed and fixed on the rear surface of the recording medium. The recording medium is preferably, for example, standard paper, special paper, or other paper S, a resin film such as polyethylene terephthalate, or a magnetic card. The conveying device 100 includes a first conveying section 110, a second conveying section 120, and a third conveying section .

[0037] The first conveying section 110 is provided downstream in the conveying direction of the fixing section 60. In Fig. 4, the direction of arrow B is the conveying direction. The first conveying section 110 temporarily stops the sheet S conveyed from the second conveying section 120, reverses the conveying direction B, and conveys the sheet S to the third conveying section 130. In other words, the first conveying section 110 functions as a switchback path. The second transport section 120 is provided upstream of the first transport section 110 in the transport direction and downstream of the fixing section 60, and transports the paper S from the fixing section 60 to the first transport section 110. The third conveying section 130 is provided downstream of the first conveying section 110 in the conveying direction, and conveys the paper S from the first conveying section 110 to the image forming section. In other words, the third conveying section 130 functions as a conveying path for the back side by switching back the paper S at the first conveying section 110. The image forming unit is, for example, an image forming unit 40 provided in an image forming apparatus 1 described later in Fig. 7. In Fig. 4, the image forming unit is not shown due to the limitations of the drawing. Therefore, the first to third conveying sections 110 to 130 are arranged in the order of second conveying section 120, first conveying section 110, and third conveying section 130 from fixing section 60 along the conveying direction. The paper S transported from the second transport section 120 to the first transport section 110 has its transport direction reversed, and in the third transport section 130, the paper S is transported with the back side of the paper S becoming the image forming surface.

[0038] <Second conveyor section> The second conveying section 120 includes a pair of second guides 121A, 121B that receive the paper S on which the image has been fixed by the fixing section 60, and multiple pairs of conveying rollers 122 that sandwich and convey the received paper S. The second conveying section 120 conveys the paper S on which the image has been fixed by the fixing section 60 to the first conveying section 110 on the downstream side at a predetermined conveying speed. The pair of second guides 121A, 121B are disposed opposite to each other, and a transport path for transporting the paper S is formed between the pair of second guides 121A, 121B. The pairs of transport rollers 122 are exposed from notched portions (not shown) formed at predetermined positions of the second guides 121A and 121B and are rotatable.

[0039] FIG. 5 is a schematic cross-sectional view of the second guide 121A and the paper S. As shown in FIG. Of the pair of second guides 121A, 121B, the second guide 121A that supports the non-image surface Sa of the paper S is made of a material with lower thermal conductivity than sheet metal. The second guide 121B (see FIG. 4) that supports the image surface Sb of the paper S is also preferably made of a material with lower thermal conductivity than sheet metal. Examples of materials having a lower thermal conductivity than the metal plate include resins, such as polycarbonate and ABS resin. The thermal conductivity of the metal plate is within a range of 30 to 80 W / mK, and the thermal conductivity of the second guide 121A is preferably 1 W / mK or less. The pairs of transport rollers 122 are preferably made of ethylene propylene rubber, etc. The thermal conductivity of ethylene propylene rubber is 1 W / mK or less.

[0040] <First conveyor section> The first conveying section 110 includes a pair of first guides 111A, 111B that receive the paper sheet S conveyed from the second conveying section 120, and multiple pairs of rollers 112 that sandwich and convey the received paper sheet S. The first conveying section 110 reverses the conveying direction of the paper sheet S received from the second conveying section 120 and conveys the paper sheet S to the downstream third conveying section 130 at a predetermined conveying speed. The pair of first guides 111A, 111B are disposed opposite to each other, and a transport path for transporting the paper S is formed between the pair of first guides 111A, 111B. As shown in FIG. 3A, of the pair of first guides 111A, 111B, the first guide 111A, which supports the non-image surface Sa of the paper S, includes a metal plate 113 and a resin sheet 114 provided on the conveying surface of the metal plate 113. A sheet 115 having a higher thermal conductivity than the metal sheet 113 is provided between the metal sheet 113 and the resin sheet 114. As a result, the sheet 115 having a higher thermal conductivity is provided opposite the non-image surface Sa of the paper S via the resin sheet 114.

[0041] The material of the first guide 111B (see Figure 4) that supports the image surface Sb of the paper S is not particularly limited, and may be sheet metal, or like the first guide 111A, may be a three-layer structure of sheet metal, a sheet with high thermal conductivity, and a resin sheet, or may be a two-layer structure of sheet metal and a resin sheet.

[0042] The metal plate 113 is made of, for example, ordinary steel (SPCC, SPHC), hot-dip galvanized steel (SGCC), etc. Here, SPCC is a cold-rolled steel plate, and SPHC is a hot-rolled steel plate. As described above, the thermal conductivity of the metal plate 113 made of such a metal plate is preferably within the range of 30 to 80 W / mK. The high thermal conductivity sheet 115 preferably has a thermal conductivity in the range of 150 to 300 W / mK, which is higher than the thermal conductivity of the metal plate 113. The high thermal conductivity sheet 115 is made of, for example, aluminum (thermal conductivity: 237 W / mK), copper (thermal conductivity: 403 W / mK), silver (428 W / mK), etc., and is preferably made of aluminum because it is inexpensive.

[0043] Resin sheet 114 preferably has a thermal conductivity of 1 W / mK or less, lower than that of metal plate 113. Resin sheet 114 is preferably made of, for example, high-density polyethylene, polytetrafluoroethylene (PTFE), or the like. Here, polyethylene is classified into the following types 1) to 3) based on differences in density. 1) Density 0.910g / cm 3 More than 0.930g / cm 3 Less than low density polyethylene (LDPE) 2) Density 0.930g / cm 3 More than 0.942g / cm 3 Less than medium density polyethylene (MDPE) 3) Density 0.942g / cm 3 The above is high density polyethylene (HDPE) The resin sheet 114 according to the present invention has a density of 0.942 g / cm 3 It is preferable that the material is made of high density polyethylene.

[0044] It is preferable that the high thermal conductivity sheet 115 is thinner than the metal plate 113 and the resin sheet 114. In particular, it is preferable that the high thermal conductivity sheet 115 is thinner than 0.1 mm. If the low thermal conductivity sheet 115 is thin, the conveyance path will not become narrow, and the paper S can be conveyed smoothly. Furthermore, since the purpose of the high thermal conductivity sheet 115 is to disperse the heat of the resin sheet 114, it can still fully fulfill its function even if it is thin.

[0045] The thickness of the metal plate 113 is preferably within a range of 0.8 to 2.0 mm. The thickness of the resin sheet 114 is preferably within the range of 0.05 to 0.5 mm, from the viewpoint of allowing smooth transport without filling the transport path too much with the resin sheet and slowing down heat conduction.

[0046] It is preferable that the sheet 115 having high thermal conductivity is provided on the entire surface of the resin sheet 114 opposite to the conveying surface (the entire back surface) in order to reliably prevent condensation. Furthermore, it is preferable that resin sheet 114 and sheet 115 with high thermal conductivity cover the entire width of paper S. By covering the entire width of paper S with resin sheet 114 and sheet 115 with high thermal conductivity, there are no places where metal plate 113 and paper S come into direct contact, and condensation can be reliably prevented.

[0047] Furthermore, the sheet 115 with high thermal conductivity is preferably divided in the width direction of the paper S so as to facilitate the work of attaching it to the metal plate 113. The sheet 115 with high thermal conductivity is preferably attached to the metal plate 113 by adhesive or the like. Similarly, from the viewpoint of ease of attachment, it is preferable that resin sheet 114 is also divided in the width direction of paper S. It is also preferable that resin sheet 114 is attached to sheet 115 having high thermal conductivity with an adhesive or the like. The pairs of transport rollers 112 are preferably made of ethylene propylene rubber or the like.

[0048] <Third conveyor section> The third conveying section 130 includes a pair of third guides 131A, 131B that receive the paper S conveyed from the first conveying section 110, and multiple pairs of conveying rollers 132 that sandwich and convey the received paper S. The third conveying section 130 conveys the paper S received from the first conveying section 110 at a predetermined conveying speed to a downstream image forming section (image forming section 40 in FIG. 5) for double-sided printing. The pair of third guides 131A, 131B are disposed opposite to each other, and a transport path for transporting the paper S is formed between the pair of third guides 131A, 131B.

[0049] FIG. 6 is a schematic cross-sectional view of the third guide 131A and the paper S. As shown in FIG. Of the pair of third guides 131A, 131B, the third guide 131A that supports the non-image surface Sa of the sheet S is preferably made of a metal plate, so that the non-image surface Sa of the sheet S comes into direct contact with the metal plate. The material of third guide 131B (see FIG. 4) that supports image surface Sb of sheet S is not particularly limited, but it is preferable that it is made of sheet metal like third guide 131A because it is inexpensive. The metal plates used in the third guides 131A and 131B are formed from metal plates such as ordinary steel (SPCC, SPHC) and hot-dip galvanized steel (SGCC), similar to the metal plates 111A and 111B of the first conveying section 110. The pairs of transport rollers 132 are preferably made of ethylene propylene rubber or the like.

[0050] According to the conveying device 100 configured as described above, the sheet S on which the image has been fixed in the fixing section 60 is conveyed with the non-image side Sa supported by the second guide 121A of the second conveying section 120. Here, the second guide 121A, which first comes into contact with the sheet S heated in the fixing section 60, is prone to condensation, but because the second guide 121A is made of a material with low thermal conductivity, condensation does not occur. Next, the paper S is conveyed with its non-image side Sa supported by first guide 111A of first conveying section 110. Here, first guide 111A has a three-layer structure consisting of metal plate 113, highly thermally conductive sheet 115, and resin sheet 114. Therefore, even if the surrounding air is heated by the high-temperature paper, highly thermally conductive sheet 115 dissipates the heat to the surrounding area. Therefore, after the paper S passes through, the temperature rise of resin sheet 114 itself is suppressed, and the temperature rise of air G heated by resin sheet 114 is also suppressed. By suppressing the temperature rise of air G, when resin sheet 114 is cooled by metal plate 113, a temperature difference between resin sheet 114 and air G is less likely to occur, and condensation can be prevented. Furthermore, the sheet S is conveyed from the second conveying section 120 with its non-image side Sa supported by the third guide 131A of the third conveying section 130. Here, the third guide 131A is made of sheet metal, and the temperature of the sheet S has dropped when it is conveyed by the third guide 131A. Therefore, condensation does not occur due to the temperature difference with the sheet metal of the third guide 131A. This prevents transfer problems during double-sided printing caused by this condensation.

[0051] [Image forming equipment] Next, an image forming apparatus equipped with the above-described conveying device will be described. 7 is a schematic diagram showing the configuration of an image forming apparatus equipped with a conveying device. As shown in FIG. 7, the image forming apparatus 1 is an electrophotographic image forming apparatus. The image forming apparatus 1 includes an image reading unit 10, an operation display unit 20, an image processing unit 30, an image forming unit 40, a paper feeding unit 50, a paper ejection unit 52, a conveying device 100, a fixing unit 60, and a control unit .

[0052] The control unit 70 is a device that cooperates with the deployed program to centrally control the operation of each block of the image forming apparatus 1. The control unit 70 includes, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), and a RAM (Random Access Memory).

[0053] The image reading unit 10 is configured to include an automatic document feeder 11 called an ADF (Auto Document Feeder), an original image scanning device 12 (scanner), and the like. The operation display unit 20 is configured, for example, by a liquid crystal display (LCD) with a touch panel, and functions as a display unit and an operation unit. The image processing unit 30 includes a circuit for performing digital image processing on input image data according to initial settings or user settings.

[0054] The image forming section 40 includes an image forming unit 41 for forming an image using color toners of Y, M, C, and K components based on input image data, an intermediate transfer unit 42, a secondary transfer unit 43, and the like.

[0055] The image forming unit 41 is composed of four image forming units 41Y, 41M, 41C, and 41K for the Y component, M component, C component, and K component. Because the image forming units 41Y, 41M, 41C, and 41K have similar configurations, for ease of illustration and explanation, the common components are denoted by the same reference numerals, and when distinguishing between them, the reference numerals are suffixed with Y, M, C, or K. In FIG. 7, only the components of the image forming unit 41Y for the Y component are labeled, and the components of the other image forming units 41M, 41C, and 41K are not labeled.

[0056] The image forming unit 41 includes an exposure device 411, a developing device 412, a photoconductor 200, a charging device 414, a drum cleaning device 415, and the like.

[0057] The photoreceptor 200 is an electrophotographic photoreceptor. The photoreceptor 200 is a negatively charged organic photoconductor (OPC) having a conductive substrate, an undercoat layer (UCL), a charge generation layer (CGL), a charge transport layer (CTL), and an overcoat layer (OCL).

[0058] The charging device 414 is a non-contact charging device that uses, for example, corona discharge, or may be a contact charging device that contacts the photoconductor 200 to charge it. The exposure device 411 is composed of, for example, a semiconductor laser. The developing device 412 is a developing device for a two-component developer, and contains a developer for each color component. The developer may be, for example, a two-component developer made of small particle size toner and a magnetic material. The drum cleaning device 415 has a drum cleaning blade, such as an elastic blade, that is arranged so as to be in sliding contact with the surface of the photoreceptor 200 .

[0059] The intermediate transfer unit 42 includes an intermediate transfer belt 421, a primary transfer roller 422, a plurality of support rollers 423 including a backup roller 423A, a belt cleaning device 426, and the like.

[0060] The intermediate transfer belt 421 is an endless belt that is looped and stretched around a plurality of support rollers 423. At least one of the support rollers 423 is a drive roller, and the others are driven rollers. The belt cleaning device 426 has a belt cleaning blade such as an elastic blade that is arranged so as to be in sliding contact with the surface of the intermediate transfer belt 421 .

[0061] The secondary transfer unit 43 includes, for example, a secondary transfer roller 431. The secondary transfer unit 43 may have a configuration in which a secondary transfer belt is stretched in a loop shape around a plurality of support rollers including the secondary transfer roller.

[0062] The fixing section 60 is disposed as a unit within the fixing device F. The fixing section 60 has an endless fixing belt 61, two rollers 64 and 65 for supporting the fixing belt 61 in an endless manner, a heating device 63 for heating the fixing belt 61 supported by the rollers 64 and 65, and a pressure roller 62 disposed so as to be biased relative to the roller 64.

[0063] Roller 64 is disposed opposite pressure roller 62 across fixing belt 61, and has a diameter of 50 mm or more. Rollers 64 and 65 support fixing belt 61 on an endless track with a tension of 45 N. For example, roller 64 is a drive roller, and roller 65 is a driven roller. The heating device 63 is configured by, for example, a halogen lamp or a resistance heating element, and is built into the roller 65 . Pressure roller 62 is disposed so as to be able to move toward and away from roller 64. Pressure roller 62 presses against fixing belt 61 supported by roller 64, thereby forming a fixing nip portion that holds and transports paper S.

[0064] An electromagnetic induction heating (IH) type heating device may be used as the heating device 63. An air separation unit may also be arranged inside the fixing device F to separate the paper S from the fixing belt 61 or the pressure roller 62 by blowing air thereon.

[0065] The paper feed section 50 has three paper feed tray units 51a to 51c and a plurality of roller units including an intermediate conveyance roller unit 54, a loop roller unit 55, and a registration roller unit 56. The paper feed tray units 51a to 51c store paper sheets S identified based on basis weight, size, etc., in predetermined types. The paper discharge unit 52 transports the paper to the outside of the image forming apparatus 1.

[0066] The transport device 100 is the transport device 100 shown in Fig. 4, and has first to third transport sections 110 to 130 which form transport paths when double-sided printing is performed. Here, a description of the transport device 100 will be omitted.

[0067] In the image forming apparatus 1, the automatic document feeder 11 conveys documents D placed on a document tray using a conveying mechanism and sends them to the document image scanning device 12. The automatic document feeder 11 can continuously read images (including both sides) of multiple documents D placed on the document tray all at once. The document image scanning device 12 optically scans the document transported from the automatic document feeder 11 onto the contact glass or the document placed on the contact glass, and forms an image of the reflected light from the document on the light receiving surface of a CCD (Charge Coupled Device) sensor 12a, thereby reading the document image. The image reading unit 10 generates input image data based on the results of reading by the document image scanning device 12. This input image data is subjected to predetermined image processing in the image processing unit 30 as necessary.

[0068] The control unit 70 controls the drive current supplied to a drive motor (not shown) that rotates the photoconductor 100. As a result, the photoconductor 100 rotates at a constant peripheral speed. The charging device 414 uniformly charges the photoconductive surface of the photoconductor 100 to a negative polarity. The exposure device 411 irradiates the photoconductor 100 with laser light corresponding to an image of each color component, and an electrostatic latent image of each color component is formed on the surface of the photoconductor 100 due to a potential difference with the surroundings. The developing device 412 visualizes the electrostatic latent image by attaching toner of each color component to the surface of the photoconductor 100, thereby forming a toner image.

[0069] Meanwhile, intermediate transfer belt 421 runs at a constant speed in the direction of arrow A by the rotation of support roller 423, which serves as a drive roller. Primary transfer roller 422 presses intermediate transfer belt 421 against photoreceptor 100, forming a primary transfer nip, and the toner images of each color on photoreceptor 100 are primarily transferred onto intermediate transfer belt 421 so that the toner images of each color are sequentially superimposed on one another. Residual toner remaining on the surface of photoreceptor 100 after primary transfer is removed from the surface by the elastic blade of drum cleaning device 415, which contacts the surface of photoreceptor 100.

[0070] Meanwhile, a secondary transfer nip is formed by pressing secondary transfer roller 431 against backup roller 423A via intermediate transfer belt 421. Paper S fed from paper feed unit 51 or conveyance device 100 is conveyed to the secondary nip transfer unit. The skew and widthwise position (bias) of paper S are corrected during the conveyance process by multiple roller units including intermediate conveyance roller unit 54, loop roller unit 55, and registration roller unit 56.

[0071] When the paper S passes through the secondary transfer nip, the toner image carried on the intermediate transfer belt 421 is secondarily transferred onto the paper S. The paper S onto which the toner image has been transferred is transported toward the fixing unit 60. Residual toner remaining on the surface of the intermediate transfer belt 421 after the secondary transfer is removed from the surface by the elastic blade of the belt cleaning device 426, which contacts the surface of the intermediate transfer belt 421.

[0072] The fixing unit 60 heats and presses the conveyed paper S in a fixing nip, thereby fixing the toner image to the paper S. The drive control of the fixing belt 61, pressure roller 62, heating device 63, etc. is performed by the control unit 70.

[0073] The fixing belt 61 is heated by the heating device 63, and as a result, the fixing belt 61 is uniformly heated at a predetermined fixing temperature (for example, 170°C) across the width direction. The fixing temperature is a temperature that can supply the thermal energy required to melt the toner on the paper S, and differs depending on the type of paper S on which an image is formed.

[0074] In the case of double-sided printing, the conveying device 100 first conveys the paper S to the first conveying section 110, which is a switchback path, and then switches back to convey the paper S to the third conveying section 130, which is a conveying path for the back side, thereby inverting the paper S and supplying it upstream of the loop roller section 55. Then, the paper S is again supplied to the secondary transfer nip section, where the desired toner image is transferred onto the paper S, and then the toner image is fixed to the paper S in the fixing section 60.

[0075] The sheet S on which the desired image has been formed is then discharged to the outside of the image forming apparatus 1 by a sheet discharge section 52 equipped with a sheet discharge roller 52a.

[0076] The description of the above embodiment is merely an example of the conveying device and image forming apparatus of the present invention, and is not intended to limit the scope of the present invention. The detailed configuration and operation of each part constituting the device may be modified as appropriate without departing from the spirit of the present invention. For example, in the above-described embodiment, the conveying device of the present invention is provided in the image forming apparatus as a conveying device that conveys paper for double-sided printing after fixing, but it is not limited to this and may also be provided as a conveying device that ejects paper directly out of the image forming apparatus after fixing. [Example]

[0077] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these. In the following examples, unless otherwise specified, operations were carried out at room temperature (25°C).

[0078] In order to confirm the effect of providing an aluminum sheet on the first guide, two levels of first guide [1] and first guide [2] shown below were prepared.

[0079] <First guide [1] (comparison example)> The first guide [1] was made by attaching a high-density polyethylene sheet to the surface of a metal plate. The metal plate was made of ordinary steel (SPCC).

[0080] <First guide [2] (present invention)> An aluminum sheet was attached to the surface of the metal plate, and a high-density polyethylene sheet was further attached to the aluminum sheet to fabricate the first guide 2. The metal plate was made of ordinary steel (SPCC).

[0081] <Evaluation of transferability> Each of the produced first guides was attached to a production printing machine, and the transferability was evaluated under the following conditions. (Operating environment) To create conditions that favor condensation, the production printing machine was left in an environment with a temperature of 10°C and humidity of 20% for more than 24 hours before use. Each time data was collected under a certain condition, the temperature of the metal plate where a defect was expected to occur was measured, and after confirming that the temperature was 10 degrees, the next condition was carried out.

[0082] (Paper used) To facilitate condensation, the paper used was left unopened in an environment with a temperature of 30°C and humidity of 80% for 48 hours or more until just before use. The specific paper used was POD Gloss Coat 128g, a generally recommended paper, and the paper size selected was SRA3, which is relatively large among standard sizes excluding irregular sizes, in order to improve the accuracy of detecting defects in the width direction of the paper.

[0083] (Image conditions) As an image condition where defects are likely to occur, a two-layer image with a printing rate of 100% was selected. The two-layer image was 100% magenta and 100% cyan. (Number of prints) Twenty sheets were printed continuously on both sides, and the number of sheets on which transfer was not performed was counted. (Repetition condition) To clearly demonstrate the effect, the experiment was carried out three times, alternating between using the first guide [1] and the first guide [2].

[0084] [Table 1]

[0085] As shown in the above results, it was found that the first guide in which an aluminum sheet was provided between the metal plate and the high-density polyethylene sheet as in the present invention did not cause transfer defects, whereas the first guide made of the metal plate and the high-density polyethylene sheet as in the comparative example did cause transfer defects. [Explanation of symbols]

[0086] 1. Image forming device 10 Image reading unit 11 Automatic document feeder 12 Original image scanning device 12a CCD sensor 20 Operation display section 30 Image processing section 40 Image forming unit 41 Image forming unit 42 Intermediate transfer unit 43 Secondary transfer unit 50 Paper transport section 51 Paper feed section 51a~51c Paper feed tray unit 52 Paper output section 52a Paper ejection roller 54 Intermediate transport roller section 55 Loop roller section 56 Registration roller section 60 Fixing unit 61 Fixing belt 62 Pressure roller 63 Heating device 64, 65 Roller 70 Control Unit 100 conveying device 110 First conveying section 111A, 111B First Guide 112 Transport roller 113 Sheet Metal 114 Resin Sheet 115 High thermal conductivity sheet 120 Second conveying section 121A, 121B 2nd Guide 122 Transport roller 130 Third conveying section 131A, 131B 3rd Guide 132 Transport roller 200 Photoreceptor 411 Exposure equipment 412 Developing device 414 Charging device 415 Drum cleaning device 421 Intermediate transfer belt 422 Primary transfer roller 423 Support Roller 423A Backup Roller 426 Belt cleaning device 431 Secondary transfer roller B Conveying direction D Manuscript F Fixing unit G Air S paper W Condensation

Claims

1. A conveying device that conveys a recording medium on which an image has been fixed by a fixing unit, a first guide for conveying the recording medium downstream of the fixing unit; The first guide includes a metal plate and a resin sheet provided on a conveyance surface of the metal plate, A sheet having a higher thermal conductivity than the metal plate is provided between the metal plate and the resin sheet. A conveying device characterized by:

2. The sheet with high thermal conductivity is provided opposite to the non-image side of the recording medium via the resin sheet.

2. The conveying device according to claim 1.

3. a second guide is provided upstream of the first guide and downstream of the fixing portion; The second guide is made of a material having a lower thermal conductivity than sheet metal.

2. The conveying device according to claim 1.

4. a third guide is provided downstream of the first guide, the third guide is formed of sheet metal, The metal plate comes into direct contact with the non-image surface of the recording medium.

2. The conveying device according to claim 1.

5. The sheet with high thermal conductivity is thinner than the metal plate and the resin sheet of the first guide.

2. The conveying device according to claim 1.

6. The thickness of the sheet with high thermal conductivity is less than 0.1 mm.

6. The conveying device according to claim 5.

7. The material of the sheet with high thermal conductivity is aluminum.

2. The conveying device according to claim 1.

8. The material of the resin sheet is high-density polyethylene.

2. The conveying device according to claim 1.

9. The sheet with high thermal conductivity is provided on the entire surface of the resin sheet opposite to the conveying surface.

2. The conveying device according to claim 1.

10. The resin sheet and the sheet with high thermal conductivity cover the entire width of the recording medium.

2. The conveying device according to claim 1.

11. The resin sheet and the sheet with high thermal conductivity are provided in a divided manner in the width direction of the recording medium.

2. The conveying device according to claim 1.

12. 12. An image forming apparatus comprising: an image forming unit that forms an image on a recording medium; a fixing unit that fixes the image on the recording medium; and the conveying device according to claim 1 that conveys the recording medium on which the image has been fixed. An image forming apparatus characterized by:

Images