JP2021167863A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that is excellent in utilization efficiency of heat, and an image forming apparatus including such a fixing device.SOLUTION: A fixing device comprises: a fixing belt 61; a fixing pad 63; and a support member 66. The fixing pad 63 has a first pad surface 71 opposite to a fixing nip part N, and a second pad surface 72 opposite to the support member 66. The fixing pad 63 is provided with at least one concave part 80 of a first concave part 81 opening in the first pad surface 71 and a second concave part opening in the second pad surface 72. The concave part 80 extends on a virtual straight line 120. A length of the virtual straight line 120 between the first pad surface 71 and the second pad surface 72 is T, and when a total length of the concave part 80 in the linear direction of the virtual straight line 120 is H, a total length H of the concave part 80 is equal to or more than a thickness t (=T-H) of the fixing pad 63 on the virtual straight line 120.SELECTED DRAWING: Figure 3

Description

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

For example, Japanese Patent Application Laid-Open No. 2017-72659 (Patent Document 1) describes a cylindrical fixing sleeve that has a rotatable shape, a sliding member that contacts the fixing sleeve inside the fixing sleeve, and a fixing sleeve. A fixing device including a pressure roller which is arranged at a position facing a sliding member and pressurizes the fixing sleeve and a halogen heater for raising the temperature of the fixing sleeve is disclosed.

Further, Japanese Patent Application Laid-Open No. 2006-47769 (Patent Document 2) describes an endless fixing belt, a pressure roll that comes into contact with the outer peripheral surface of the fixing belt, and a concave pressure between the fixing belt and the pressure roll. A fixing device including a pressing member for acting on the above-mentioned is disclosed.

Japanese Unexamined Patent Publication No. 2017-72659 Japanese Unexamined Patent Publication No. 2006-47769

As disclosed in the above-mentioned patent document, by pressing the fixing belt toward the fixing pad by the pressure roller, a fixing nip portion for transporting a recording medium such as paper is formed between the pressure roller and the fixing belt. A fixing device is known. In such a fixing device, the fixing belt is heated to a high temperature by a heating source such as a halogen heater, and heat is transferred from the fixing belt to the recording medium at the fixing nip portion to melt the toner on the recording medium and form the recording medium. Fix it.

However, the heat from the fixing belt is transferred not only to the recording medium but also to the fixing pad side. In this case, heat flows out to the support member that supports the fixing pad through the fixing pad, so that the heat utilization efficiency is impaired. In particular, when the support member is made of a metal plate having a large thickness (for example, 2 mm or more) for strength reasons, the heat capacity of the support member becomes large, so that the heat utilization efficiency may be significantly lowered.

Therefore, an object of the present invention is to solve the above-mentioned problems, and to provide a fixing device having excellent heat utilization efficiency and an image forming device provided with such a fixing device.

The fixing device according to the present invention includes an endless fixing belt, a heating source for heating the fixing belt, a fixing pad arranged on the inner peripheral side of the fixing belt, a support member for supporting the fixing pad, and a fixing belt. Is provided with a pressure roller for forming a fixing nip portion through which the recording medium is conveyed together with the fixing belt. The fixing pad has a first pad surface facing the fixing nip portion and a second pad surface arranged on the back side of the first pad surface and facing the support member. The fixing pad has a bottomed first recess that opens on the surface of the first pad and dents toward the surface of the second pad, and a bottomed second recess that opens on the surface of the second pad and dents toward the surface of the first pad. At least one of the recesses is provided. The recess extends on a virtual straight line extending between the surface of the first pad and the surface of the second pad. When the length of the virtual straight line between the surface of the first pad and the surface of the second pad is T and the total length of the recess in the linear direction of the virtual straight line is H, the total length H of the recess is the fixing pad on the virtual straight line. Thickness t (= TH) or more.

According to the fixing device configured in this way, when the heat from the fixing belt is transferred to the support member through the fixing pad, the recess can function as a heat insulating layer in the fixing pad. At this time, since the total length H of the recess is equal to or greater than the thickness t (= TH) of the fixing pad on the virtual straight line on which the recess extends, the heat insulating effect of the recess can be efficiently enhanced. As a result, heat is less likely to be transferred toward the support member, so that heat can be efficiently used by fixing the toner in the fixing nip portion.

Further, preferably, the fixing pad is provided with at least a first recess.
According to the fixing device configured in this way, heat is less likely to be transferred from the fixing belt to the fixing pad, so that the efficiency of heat utilization in the fixing nip portion can be further improved.

Further, preferably, the fixing pad is provided with a plurality of first recesses.
According to the fixing device configured in this way, the heat insulating effect of the first recess is further enhanced, so that the heat utilization efficiency in the fixing nip portion can be further improved.

Also preferably, the surface of the first pad is disposed between the first recesses adjacent to each other and has a convex surface extending along the fixing belt.

According to the fixing device configured in this way, by supporting the fixing belt by the convex surface between the first recesses adjacent to each other, it is possible to prevent the fixing belt from falling inside the first recess. As a result, the pressure distribution applied to the recording medium at the fixing nip portion becomes more uniform, so that the toner can be fixed to the recording medium with good quality.

Further, preferably, a plurality of convex surfaces are arranged in a predetermined range in a direction orthogonal to the transport direction of the recording medium. When an arbitrary straight line extending along the transport direction of the recording medium is projected onto the surface of the first pad, a convex surface is formed on at least a part of the straight line at all positions in a predetermined range in the direction orthogonal to the transport direction of the recording medium. Exists.

According to the fixing device configured in this way, the recording medium has an opportunity to pass on the convex surface at all the positions in the predetermined range in the direction orthogonal to the transport direction of the recording medium. As a result, the pressure distribution applied to the recording medium at the fixing nip portion becomes more uniform, so that the toner can be fixed to the recording medium with even better quality.

Further, preferably, the plurality of first recesses are arranged so as to be spaced apart from each other in a direction orthogonal to the transport direction of the recording medium. The opening of each first recess on the surface of the first pad extends along an oblique direction with respect to the transport direction of the recording medium.

According to the fixing device configured in this way, when the fixing belt passes through the fixing nip portion, it is possible to prevent an excessive force from being applied to the fixing belt from the edge portion formed by the opening of the first recess on the surface of the first pad. can. As a result, it is possible to prevent the surface of the fixing belt from being scratched or the fixing belt from being damaged.

Further, preferably, the opening of each first recess on the surface of the first pad approaches the center line of the surface of the first pad extending along the transport direction of the recording medium from the upstream side to the downstream side in the transport direction of the recording medium. Extend like.

According to the fixing device configured in this way, the lubricant such as grease supplied to the fixing belt may move along the opening of the first recess on the surface of the first pad as the fixing step is executed. be. Even in such a case, since the lubricant moves toward the center side of the surface of the first pad in the direction orthogonal to the transport direction of the recording medium, the outflow of the lubricant can be suppressed.

Further, preferably, the plurality of first recesses are provided side by side in a predetermined direction. The opening width of the first concave portion in the predetermined direction is smaller than the width of the convex surface in the predetermined direction.

According to the fixing device configured in this way, it is possible to effectively prevent the fixing belt from falling inside the first recess. As a result, the pressure distribution applied to the recording medium at the fixing nip portion becomes more uniform, so that the toner can be fixed to the recording medium with even better quality.

Further, preferably, the first recesses are provided so as to be symmetrically arranged on both sides of the center line of the surface of the first pad extending along the transport direction of the recording medium.

According to the fixing device configured in this way, the pressure distribution applied to the recording medium at the fixing nip portion can be made uniform on both sides of the center line of the surface of the first pad. As a result, it is possible to suppress the meandering of the recording medium in the fixing nip portion and to suppress the uneven distribution of the lubricant such as grease supplied to the fixing belt.

Further, preferably, the fixing device is provided so as to cover the surface of the first pad, and further includes a sliding sheet that closes the opening of the first recess on the surface of the first pad.

According to the fixing device configured in this way, the opening of the first recess on the surface of the first pad is closed by the sliding sheet, so that a lubricant such as grease or a wear piece of the fixing belt or the fixing pad is removed. It is possible to prevent the invasion into the first recess. This makes it possible to prevent a decrease in the heat insulating effect due to the intrusion of foreign matter into the first recess.

Further, preferably, the first recess is provided so that the opening area of the first recess becomes smaller as the opening area of the first recess approaches the surface of the second pad from the surface of the first pad.

According to the fixing device configured in this way, by providing the side wall of the first recess with an inclination, the fixing pad receiving the force from the pressure roller is less likely to buckle. As a result, damage to the fixing pad can be suppressed.

Further, preferably, only an air layer is provided inside the recess.
According to the fixing device configured in this way, the heat insulating effect of the concave portion is further enhanced, so that the heat utilization efficiency in the fixing nip portion can be further improved.

Further, preferably, the fixing pad further has a third pad surface arranged on the upstream side and the downstream side in the transport direction of the recording medium with respect to the first pad surface. The fixing pad is further provided with a bottomed third recess that opens on the surface of the third pad and dents toward the surface of the second pad.

According to the fixing device configured as described above, the heat utilization efficiency in the fixing nip portion can be further improved by further providing the third recess in the fixing pad.

The image forming apparatus according to the present invention includes the fixing apparatus according to any one of the above.
According to the image forming apparatus configured as described above, it is possible to realize an image forming apparatus including a fixing apparatus having excellent heat utilization efficiency.

As described above, according to the present invention, it is possible to provide a fixing device having excellent heat utilization efficiency and an image forming device including such a fixing device.

It is a figure which shows schematicly about the whole structure of the image forming apparatus. It is a figure which shows the fixing device in Embodiment 1 of this invention. It is sectional drawing which shows the fixing device of the range surrounded by the alternate long and short dash line III in FIG. It is a top view which shows the fixing pad seen in the pressing direction from a pressure roller. It is sectional drawing which shows another form of the fixing pad in FIG. It is sectional drawing which shows still another form of the fixing pad in FIG. It is a figure for demonstrating the way of heat transfer in a fixing device. It is sectional drawing which shows typically the mode of the fixing belt and the sliding sheet when the surface of the 1st pad has a convex surface. It is sectional drawing which shows typically the mode of the fixing belt and the sliding sheet when the surface of the 1st pad does not have a convex surface. It is a top view which shows the fixing pad of the fixing device in the 1st modification. It is a top view which shows the fixing pad of the fixing device in the 2nd modification. It is a top view which shows the fixing pad of the fixing device in the 3rd modification. It is a top view which shows the fixing pad of the fixing device in 4th modification. It is a top view which shows the fixing pad of the fixing device in 5th modification. It is a top view which shows the fixing pad of the fixing device in 6th modification. It is a top view which shows the fixing pad of the range surrounded by the alternate long and short dash line XVI in FIG. It is a top view which shows the fixing pad of the fixing device in 7th modification. It is a top view which shows the fixing pad of the range surrounded by the alternate long and short dash line XVIII in FIG. It is sectional drawing which shows the fixing pad of the fixing device in 8th modification. It is sectional drawing which shows the fixing device in 9th modification. It is sectional drawing which shows the fixing device in 10th modification. It is sectional drawing which shows the fixing device in 11th modification.

Embodiments of the present invention will be described with reference to the drawings. In the drawings referred to below, the same or corresponding members are given the same number.

(Embodiment 1)
FIG. 1 is a diagram schematically showing an overall configuration of an image forming apparatus. First, the overall configuration of the image forming apparatus will be described.

With reference to FIG. 1, the image forming apparatus 1 is an intermediate transfer type color image forming apparatus using an electrophotographic process technique. The image forming apparatus 1 primary transfers the Y (yellow), M (magenta), C (cyan), and K (black) color toner images formed on the photoconductor drum 413 to the intermediate transfer belt 21. The image forming apparatus 1 forms an image by superimposing toner images of four colors on the intermediate transfer belt 21 and then secondarily transferring the toner images to a recording medium to be conveyed. The recording medium is, for example, plain paper.

A tandem system is adopted for the image forming apparatus 1. In the tandem system, the photoconductor drums 413 corresponding to the four colors of YMCK are arranged along the traveling direction of the intermediate transfer belt 21 (the direction indicated by the arrow A in FIG. 1). In the tandem method, the four-color toner images of YMCK are sequentially transferred onto the intermediate transfer belt 21 in one procedure.

The image forming apparatus 1 includes an image reading unit 10, an image processing unit 30, an image forming unit 40, a conveying unit 50, and a fixing device 60.

The image reading unit 10 includes an automatic document feeding device 11 called an ADF (Auto Document Feeder) and a document image scanning device 12 (scanner). The automatic document feeding device 11 conveys the document J placed on the document tray by the conveying mechanism and sends it out to the document image scanning device 12. The automatic document feeding device 11 makes it possible to continuously read a large number of images (including both sides) of documents J placed on the document tray at once.

The document image scanning device 12 optically scans the document conveyed on the contact glass from the automatic document feeding device 11 or the document placed on the contact glass. The document image scanning device 12 forms an image of the reflected light from the document on the light receiving surface of the CCD (Charge Coupled Device) sensor 12a, and reads the document image. The image scanning unit 10 generates input image data based on the scanning result by the document image scanning device 12. The image processing unit 30 performs predetermined image processing on the input image data.

The image processing unit 30 includes a circuit or the like that performs digital image processing according to initial settings or user settings on the input image data generated by the image reading unit 10. For example, the image processing unit 30 performs gradation correction based on gradation correction data (gradation correction table).

The image processing unit 30 performs various correction processes such as color correction and shading correction, compression processing, and the like, in addition to gradation correction, on the input image data. The image forming unit 40 is controlled based on the image data subjected to these processes.

The image forming unit 40 has an image forming unit 41Y, 41M, 41C, 41K and an intermediate transfer unit 42. The image forming units 41Y, 41M, 41C, 41K and the intermediate transfer unit 42 are toners of each color of Y component, M component, C component and K component based on the image data processed by the image processing unit 30. To form an image.

The image forming units 41Y, 41M, 41C, 41K have a similar configuration. For convenience of illustration and description, common components are indicated by the same reference numerals, and when distinguishing them, they are indicated by adding Y, M, C, and K to the reference numerals. In FIG. 1, the reference numerals are given only to the components of the image forming unit 41Y for the Y component, and the reference numerals are omitted for the other components of the image forming units 41M, 41C, 41K.

The image forming unit 41 includes an exposure device 411, a developing device 412, a photoconductor drum 413, a charging device 414, and a drum cleaning device 415. The photoconductor drum 413 is a negatively charged organic photo-conductor (OPC) having a conductive cylinder (aluminum tube) made of aluminum. The drum diameter of the photoconductor drum 413 is, for example, 80 [mm]. An undercoat layer (UCL: Under Coat Layer), a charge generation layer (CGL: Charge Generation Layer), and a charge transport layer (CTL: Charge Transport Layer) are sequentially laminated on the outer peripheral surface of the photoconductor drum 413. The photoconductor drum 413 rotates by transmitting power from a drive motor (not shown).

The charge generation layer is an organic semiconductor in which a charge generation material (for example, a phthalocyanine pigment) is dispersed in a resin binder (for example, polycarbonate). The charge generation layer is exposed by the exposure apparatus 411 to generate a pair of positive and negative charges.

The charge transport layer is composed of a hole transporting material (electron donating nitrogen-containing compound) dispersed in a resin binder (for example, polycarbonate). The charge transport layer transports the positive charges generated in the charge generation layer to the surface of the charge transport layer.

The charging device 414 uniformly charges the surface of the photoconductive drum 413 to a negative electrode. The exposure apparatus 411 is composed of, for example, a semiconductor laser. The exposure apparatus 411 irradiates the photoconductor drum 413 with a laser beam corresponding to an image of each color component.

Positive charges are generated in the charge generation layer of the photoconductor drum 413 and transported to the surface of the charge transport layer, so that the surface charge (negative charge) of the photoconductor drum 413 is neutralized. An electrostatic latent image of each color component is formed on the surface of the photoconductor drum 413 due to the potential difference from the surroundings.

The developing device 412 is a developing device of a two-component developing method. The developing device 412 visualizes the electrostatic latent image and forms the toner image by adhering the toner of each color component to the surface of the photoconductor drum 413.

The drum cleaning device 415 has a drum cleaning blade that is slidably contacted with the surface of the photoconductor drum 413. The drum cleaning device 415 removes the toner remaining on the surface of the photoconductor drum 413 after the primary transfer.

The intermediate transfer unit 42 includes an intermediate transfer belt 21, a primary transfer roller 422, a plurality of support rollers 423, a secondary transfer unit 23, and a belt cleaning device 426. The intermediate transfer belt 21 is endless. The intermediate transfer belt 21 is stretched in a loop on a plurality of support rollers 423. At least one of the plurality of support rollers 423 is composed of a driving roller, and the other is composed of a driven roller.

For example, it is preferable that the roller 423A arranged on the downstream side in the traveling direction of the intermediate transfer belt 21 from the primary transfer roller 422K for the K component is the drive roller. This makes it easier to keep the traveling speed of the intermediate transfer belt 21 constant. As the roller 423A rotates, the intermediate transfer belt 21 travels at a constant speed in the direction of arrow A.

The intermediate transfer belt 21 has conductivity and elasticity. The intermediate transfer belt 21 has a high resistance layer having a volume resistivity of, for example, 8 to 11 [logΩ · cm] on its surface. The material, thickness and hardness of the intermediate transfer belt 21 are not limited as long as they have conductivity and elasticity.

The primary transfer roller 422 is arranged on the inner peripheral surface side of the intermediate transfer belt 21. The primary transfer roller 422 is arranged to face the photoconductor drum 413. The primary transfer roller 422 is pressed against the photoconductor drum 413 with the intermediate transfer belt 21 interposed therebetween. As a result, the primary transfer nip portion N1 is formed.

When the intermediate transfer belt 21 passes through the primary transfer nip portion N1, the toner image on the photoconductor drum 413 is sequentially superimposed on the intermediate transfer belt 21 and the primary transfer is performed. Specifically, a primary transfer bias is applied to the primary transfer roller 422 to apply a charge having the opposite polarity to the toner on the back surface side (the side that comes into contact with the primary transfer roller 422) of the intermediate transfer belt 21. As a result, the toner image is electrostatically transferred to the intermediate transfer belt 21.

The toner image electrostatically transferred onto the intermediate transfer belt 21 is then conveyed to the secondary transfer unit 23. When the recording medium passes through the secondary transfer unit 23, the toner image on the intermediate transfer belt 21 is secondarily transferred to the recording medium. Specifically, a secondary transfer bias is applied to the secondary transfer roller 33 to apply a charge having the opposite polarity to the toner on the side of the recording medium that comes into contact with the secondary transfer roller 33. As a result, the toner image is electrostatically transferred to the recording medium.

The belt cleaning device 426 comes into contact with the outer peripheral surface of the intermediate transfer belt 21. The belt cleaning device 426 removes the toner remaining on the surface of the intermediate transfer belt 21 after the secondary transfer.

The recording medium on which the toner image is transferred passes through the secondary transfer unit 23 and then is conveyed to the fixing device 60. The fixing device 60 fixes the toner image on the recording medium by heating and pressurizing the recording medium on which the toner image is secondarily transferred. Details of the fixing device 60 will be described later.

The transport unit 50 transports the recording medium. The transport unit 50 includes a paper feed unit 51, a paper discharge unit 52, and a transport path unit 53. The paper feed unit 51 has a paper feed tray unit 51a, 51b, 51c. Paper S (standard paper, special paper) identified based on the basis weight, size, and the like is stored in the paper feed tray units 51a, 51b, and 51c for each preset type.

The paper S housed in the paper feed tray units 51a, 51b, 51c is sent out one by one from the uppermost portion and is conveyed to the transfer path unit 53. The transport path portion 53 has a plurality of transport roller pairs including a resist roller pair 53a. The resist roller portion in which the resist roller pair 53a is arranged corrects the inclination and deviation of the recording medium. The recording medium is conveyed to the secondary transfer unit 23 through the transfer path unit 53. In the secondary transfer unit 23, the toner image on the intermediate transfer belt 21 is collectively secondarily transferred to one surface of the paper S, and then the fixing step is performed in the fixing device 60.

The recording medium that has passed through the fixing device 60 is conveyed to the paper ejection unit 52. The paper ejection unit 52 has a transport roller pair (paper ejection roller pair) 52a. The image-formed recording medium is discharged to the outside through the transport roller pair 52a.

Subsequently, the structure of the fixing device 60 will be described in detail. FIG. 2 is a diagram showing a fixing device according to the first embodiment of the present invention.

With reference to FIGS. 1 and 2, the fixing device 60 in the present embodiment includes an endless fixing belt 61, a heating source 62, a fixing pad 63, a pressure roller 64, a heating roller 67, and a support. It has a member 66 and a sliding sheet 68.

The fixing belt 61 is formed of a belt-shaped belt body and has a shape that circulates in an annular shape. The fixing belt 61 is composed of three layers, a release layer, an elastic layer, and a base layer. The release layer is formed of a material having releasability, for example, a fluororesin having a thickness of 10 μm or more and 50 μm or less. The elastic layer is formed of a material having heat resistance, low hardness and high strength, for example, silicone rubber having a thickness of 50 μm or more and 500 μm or less. The base layer is made of a material having heat resistance and high strength, for example, polyimide, nickel or stainless steel having a thickness of 30 μm or more and 100 μm or less.

The fixing pad 63, the heating roller 67, and the heating source 62 are arranged on the inner peripheral side of the fixing belt 61. The fixing belt 61 is hung around the fixing pad 63 and the heating roller 67.

The heating source 62 comprises, for example, a halogen heater. The heating roller 67 is made of a metal such as aluminum, stainless steel or iron. The heating source 62 heats the fixing belt 61 hung around the heating roller 67 through the heating roller 67. The fixing device 60 is further provided with a temperature sensor (not shown), and the heating source 62 is controlled so as to achieve a predetermined temperature target (for example, a temperature of 150 ° C. or higher and 200 ° C. or lower).

The fixing device 60 may be of a direct heating (heating rollerless) method in which the heat generated from the heating source 62 is directly transmitted to the fixing belt 61, and in this case, the heating roller 67 is not provided.

The fixing pad 63 is made of a material having excellent heat resistance and a degree of freedom in shape. The fixing pad 63 is formed of, for example, a resin such as PEEK (polyetheretherketone), LCP (liquid crystal polymer) or PPS (polyphenylene sulfide).

The sliding sheet 68 is attached to the fixing pad 63. The sliding sheet 68 is inserted between the fixing pad 63 and the fixing belt 61. The sliding sheet 68 is provided to reduce the frictional force between the fixing pad 63 and the fixing belt 61. The sliding sheet 68 is made of, for example, a fluorine layer sheet or a sheet obtained by impregnating a glass woven fabric with a fluororesin.

The support member 66 is arranged on the inner peripheral side of the fixing belt 61. The support member 66 is arranged on the opposite side of the pressure roller 64 with the fixing pad 63 interposed therebetween. The support member 66 supports the fixing pad 63. The support member 66 is made of a metal plate such as SECC. The support member 66 has a thickness of, for example, 2 mm or more.

The pressure roller 64 is arranged on the outer peripheral side of the fixing belt 61. The pressure roller 64 is arranged so as to face the fixing pad 63 via the fixing belt 61. The pressure roller 64 presses the fixing belt 61 toward the fixing pad 63. The pressure roller 64 has an elastic layer formed of silicon rubber on the outer peripheral surface.

A fixing nip portion N is formed between the fixing belt 61 and the pressure roller 64. The fixing belt 61 and the pressure roller 64 are in pressure contact with each other at the fixing nip portion N. The pressure roller 64 is driven and rotated by a drive source (not shown) to rotate the fixing belt 61 and to drive and rotate the heating roller 67. The recording medium 110 such as paper sent to the fixing device 60 is conveyed to the fixing nip portion N as the pressure roller 64 is driven and rotated. During this time, heat is transferred from the fixing belt 61 to the recording medium 110, so that the toner transferred to the recording medium 110 is melted and fixed to the recording medium 110.

FIG. 3 is a cross-sectional view showing a fixing device in the range surrounded by the alternate long and short dash line III in FIG. FIG. 4 is a top view showing the fixing pad as seen in the pressing direction from the pressurizing roller. In FIG. 4, the direction indicated by the arrow 106 corresponds to the transport direction of the recording medium 110 in the fixing nip portion N (hereinafter, simply referred to as “the transport direction of the recording medium 110”), and the direction indicated by the arrow 107 is It corresponds to the direction orthogonal to the transport direction of the recording medium 110 in the fixing nip portion N (hereinafter, simply referred to as "the direction orthogonal to the transport direction of the recording medium 110").

With reference to FIGS. 2 to 4, the fixing pad 63 has a first pad surface 71, a second pad surface 72, and a third pad surface 73 (73u, 73d).

The first pad surface 71 is provided on the side where the fixing pad 63 faces the pressure roller 64 via the fixing belt 61. The first pad surface 71 faces the fixing nip portion N. The fixing nip portion N faces the first pad surface 71 in the pressing direction from the pressure roller 64 to the fixing pad 63.

The first pad surface 71 extends in a strip shape so that the direction orthogonal to the transport direction of the recording medium 110 (the direction of the rotation axis of the pressure roller 64) is the longitudinal direction. The first pad surface 71 is made of a curved surface. The first pad surface 71 is composed of a curved surface extending while being curved along the transport direction of the recording medium 110. The first pad surface 71 is formed of a curved surface that is curved so as to follow the outer peripheral surface of the pressure roller 64.

The second pad surface 72 is arranged on the back side of the first pad surface 71. The second pad surface 72 faces the support member 66. The second pad surface 72 is in surface contact with the support member 66. The direction from the first pad surface 71 to the second pad surface 72 corresponds to the pressing direction from the pressure roller 64 to the fixing pad 63.

The third pad surface 73 (73u, 73d) is provided on the side where the fixing pad 63 faces the pressure roller 64 via the fixing belt 61. The third pad surface 73 is arranged on the upstream side and the downstream side of the recording medium 110 in the transport direction with respect to the first pad surface 71. The second pad surface 72 is arranged on the back side of the third pad surface 73. The third pad surface 73 is formed of a curved surface continuous with the first pad surface 71 in the transport direction of the recording medium 110.

The third pad surface 73u is arranged on the upstream side of the recording medium 110 in the transport direction with respect to the first pad surface 71. The third pad surface 73d is arranged on the downstream side of the recording medium 110 in the transport direction with respect to the first pad surface 71.

The support member 66 has a support surface 76. The support surface 76 faces the fixing pad 63. The second pad surface 72 is in surface contact with the support surface 76.

The fixing pad 63 is provided with a recess 80 of at least one of a first recess 81 and a second recess 91 (see FIG. 6 described later). The fixing pad 63 is provided with a first recess 81 as a recess 80. The first recess 81 has a concave shape that opens to the surface 71 of the first pad and is recessed toward the surface 72 of the second pad. An air layer is provided inside the first recess 81. A rubber pad or the like is not provided inside the first recess 81, and therefore only an air layer is provided.

The first recess 81 forms an opening 83 on the surface 71 of the first pad. The opening 83 extends in a strip shape so that the direction orthogonal to the transport direction of the recording medium 110 is the longitudinal direction. The opening 83 extends linearly in a direction orthogonal to the transport direction of the recording medium 110. The first recess 81 is a bottomed recess and has a bottom 82. The bottom portion 82 is located at the deepest portion of the first recess 81 that is recessed toward the surface 72 of the second pad.

The recess 80 (first recess 81) extends on a virtual straight line 120 extending between the first pad surface 71 and the second pad surface 72. The virtual straight line 120 intersects the opening 83 and the bottom 82 of the first recess 81. In FIG. 3, a virtual straight line 120 passing through the center position of the first recess 81 in the transport direction of the recording medium 110 is shown, but the position where the virtual straight line 120 passes through the first recess 81 is the virtual straight line 120. Is not particularly limited as long as it is a straight line intersecting the opening 83 and the bottom 82.

When the length of the virtual straight line 120 between the first pad surface 71 and the second pad surface 72 is T and the total length of the recess 80 (first recess 81) in the linear direction of the virtual straight line 120 is H, the recess is recessed. The total length H of the 80 (first recess 81) is equal to or greater than the thickness t (= TH) of the fixing pad 63 on the virtual straight line 120 (H ≧ t (= TH)).

The depth (= H) of the first recess 81 from the opening 83 to the bottom 82 is the length (= t) from the bottom 82 of the first recess 81 to the surface 72 of the second pad in the depth direction of the first recess 81. That is all. The bottom 82 of the first recess 81 is located between the first pad surface 71 and the second pad surface 72, at the center position between the first pad surface 71 and the second pad surface, or at a position higher than that of the first pad surface 71. 2 It is provided at a position closer to the pad surface 72.

The fixing pad 63 is provided with a plurality of first recesses 81. The plurality of first recesses 81 are arranged so as to be spaced apart from each other in the transport direction of the recording medium 110.

The plurality of first recesses 81 are provided so that the thickness t of the fixing pads 63 on the virtual straight line 120 is equal to each other. Not limited to such a configuration, the plurality of first recesses 81 may be provided so that the thickness t of the fixing pads 63 on the virtual straight line 120 is different from each other.

The first pad surface 71 has a convex surface 86. The convex surface 86 is arranged between the first concave portions 81 (openings 83) adjacent to each other. The convex surface 86 extends along the fixing belt 61. The convex surface 86 is composed of a curved surface that curves from the upstream side to the downstream side in the transport direction of the recording medium 110.

The fixing belt 61 extends from the upstream side to the downstream side in the transport direction of the recording medium 110 while being curved along the convex surface 86.

The plurality of first recesses 81 are provided so that the widths of the convex surfaces 86 in the arrangement direction of the plurality of first recesses 81 (the transport direction of the recording medium 110) are equal to each other. The plurality of first recesses 81 may be provided so that the widths of the convex surfaces 86 in the arrangement direction of the plurality of first recesses 81 are different from each other. The plurality of first recesses 81 are provided so that the opening widths of the openings 83 in the arrangement direction of the plurality of first recesses 81 are equal to each other. The plurality of first recesses 81 may be provided so that the opening widths of the openings 83 in the arrangement direction of the plurality of first recesses 81 are different from each other.

Subsequently, another form of the fixing pad 63 in which the recess 80 is provided will be described. 5 and 6 are cross-sectional views showing another form of the fixing pad in FIG.

With reference to FIGS. 5 and 6, the first pad surface 71 has a first region 71J and a second region 71K. The first pad surface 71 extends parallel to the second pad surface 72 in the first region 71J. The length (thickness) of the first pad surface 71 between the first pad surface 71 and the second pad surface 72 decreases from the upstream side to the downstream side in the transport direction of the recording medium 110 in the second region 71K. As described above, it is inclined and extends with respect to the surface 72 of the second pad.

As shown in FIG. 5, the fixing pad 63 is provided with a plurality of first recesses 81 (81A, 81B, 81C, 81D) as recesses 80. The first recess 81A, the first recess 81B, the first recess 81C, and the first recess 81D are arranged in the order listed from the upstream side to the downstream side in the transport direction of the recording medium 110. The first recess 81A and the first recess 81B are opened in the first region 71J of the first pad surface 71, and the first recess 81C and the first recess 81D are opened in the second region 71K of the first pad surface 71. There is.

The recess 80 (first recess 81A) extends on a virtual straight line 120A extending between the first pad surface 71 and the second pad surface 72. When the length of the virtual straight line 120A between the first pad surface 71 and the second pad surface 72 is Ta and the total length of the recess 80 (first recess 81A) in the linear direction of the virtual straight line 120A is Ha, the recess The total length Ha of 80 (first recess 81A) is equal to or larger than the thickness ta (= Ta-Ha) of the fixing pad 63 on the virtual straight line 120A. The recess 80 (first recess 81B) extends on a virtual straight line 120B extending between the first pad surface 71 and the second pad surface 72. When the length of the virtual straight line 120B between the first pad surface 71 and the second pad surface 72 is Tb and the total length of the recess 80 (first recess 81B) in the linear direction of the virtual straight line 120B is Hb, the recess The total length Hb of 80 (first recess 81B) is equal to or larger than the thickness tb (= Tb-Hb) of the fixing pad 63 on the virtual straight line 120B.

The recess 80 (first recess 81C) extends on a virtual straight line 120C extending between the first pad surface 71 and the second pad surface 72. When the length of the virtual straight line 120C between the first pad surface 71 and the second pad surface 72 is Tc and the total length of the recess 80 (first recess 81C) in the linear direction of the virtual straight line 120C is Hc, the recess The total length Hc of the 80 (first recess 81C) is equal to or greater than the thickness tc (= Tc-Hc) of the fixing pad 63 on the virtual straight line 120C. The recess 80 (first recess 81D) extends on a virtual straight line 120D extending between the first pad surface 71 and the second pad surface 72. When the length of the virtual straight line 120D between the first pad surface 71 and the second pad surface 72 is Td and the total length of the recess 80 (first recess 81D) in the linear direction of the virtual straight line 120D is Hd, the recess The total length Hd of 80 (first recess 81D) is equal to or greater than the thickness td (= Td−Hd) of the fixing pad 63 on the virtual straight line 120D.

As shown in FIG. 6, the fixing pad 63 has a plurality of first recesses 81 (81A, 81B, 81C, 81D) and a plurality of second recesses 91 (91A, 91B, 91C, 91D) as recesses 80. And are provided.

The first recess 81A, the first recess 81B, the first recess 81C, and the first recess 81D are arranged in the order listed from the upstream side to the downstream side in the transport direction of the recording medium 110. The first recess 81A and the first recess 81B are opened in the first region 71J of the first pad surface 71, and the first recess 81C and the first recess 81D are opened in the second region 71K of the first pad surface 71. There is.

The second recess 91A, the second recess 91B, the second recess 91C, and the second recess 91D are arranged in the order listed from the upstream side to the downstream side in the transport direction of the recording medium 110. The second recess 91 has a concave shape that opens to the surface 72 of the second pad and is recessed toward the surface 71 of the first pad. Only an air layer is provided inside the second recess 91.

The second recess 91 forms an opening 93 on the surface 72 of the second pad. The opening 93 is provided in the same manner as the opening 83 of the first recess 81 on the surface 71 of the first pad. The second recess 91 is a bottomed recess and has a bottom 92. The bottom portion 92 is located at the deepest portion of the second recess 91 that is recessed toward the surface 71 of the first pad.

The depth direction of the second recess 91A from the opening 93 to the bottom 92 is the same as the depth direction of the first recess 81A from the opening 83 to the bottom 82. The bottom 92 of the second recess 91A faces the bottom 82 of the first recess 81A. The depth direction of the second recess 91B from the opening 93 to the bottom 92 is the same as the depth direction of the first recess 81B from the opening 83 to the bottom 82. The bottom 92 of the second recess 91B faces the bottom 82 of the first recess 81B. The depth direction of the second recess 91C from the opening 93 to the bottom 92 is the same as the depth direction of the first recess 81C from the opening 83 to the bottom 82. The bottom 92 of the second recess 91C faces the bottom 82 of the first recess 81C. The depth direction of the second recess 91D from the opening 93 to the bottom 92 is the same as the depth direction of the first recess 81D from the opening 83 to the bottom 82. The bottom 92 of the second recess 91D faces the bottom 82 of the first recess 81D.

The recess 80 (first recess 81A, second recess 91A) extends on a virtual straight line 120A extending between the first pad surface 71 and the second pad surface 72. The length of the virtual straight line 120A between the first pad surface 71 and the second pad surface 72 is Ta, and the total length of the recess 80 (first recess 81A, second recess 91A) in the linear direction of the virtual straight line 120A is Ha ( When = Ha1 + Ha2), the total length Ha of the recess 80 (the first recess 81A, the second recess 91A) is equal to or greater than the thickness ta (= Ta-Ha1-Ha2) of the fixing pad 63 on the virtual straight line 120A. The recess 80 (first recess 81B, second recess 91B) extends on a virtual straight line 120B extending between the first pad surface 71 and the second pad surface 72. The length of the virtual straight line 120B between the first pad surface 71 and the second pad surface 72 is Tb, and the total length of the recess 80 (first recess 81B, second recess 91B) in the linear direction of the virtual straight line 120B is Hb ( = Hb1 + Hb2), the total length Hb of the recess 80 (first recess 81B, second recess 91B) is equal to or greater than the thickness tb (= Tb-Hb1-Hb2) of the fixing pad 63 on the virtual straight line 120B.

The recess 80 (first recess 81C, second recess 91C) extends on a virtual straight line 120C extending between the first pad surface 71 and the second pad surface 72. The length of the virtual straight line 120C between the first pad surface 71 and the second pad surface 72 is Tc, and the total length of the recess 80 (first recess 81C, second recess 91C) in the linear direction of the virtual straight line 120C is Hc ( When = Hc1 + Hc2), the total length Hc of the recess 80 (first recess 81C, second recess 91C) is equal to or greater than the thickness tc (= Tc-Hc1-Hc2) of the fixing pad 63 on the virtual straight line 120C. The recess 80 (first recess 81D, second recess 91D) extends on a virtual straight line 120D extending between the first pad surface 71 and the second pad surface 72. The length of the virtual straight line 120D between the first pad surface 71 and the second pad surface 72 is Td, and the total length of the recess 80 (first recess 81D, second recess 91D) in the linear direction of the virtual straight line 120D is Hd ( When = Hd1 + Hd2), the total length Hd of the recess 80 (first recess 81D, second recess 91D) is equal to or greater than the thickness td (= Td-Hd1-Hd2) of the fixing pad 63 on the virtual straight line 120D.

The ratio of the total length H of the recess 80 to the length T of the virtual straight line 120 between the first pad surface 71 and the second pad surface 72 is preferably 50% or more and 95% or less, and 80% or more and 95% or less. It is more preferably 90% or more and 95% or less. By setting the ratio of the total length H of the recess 80 to the length T of the virtual straight line 120 between the first pad surface 71 and the second pad surface 72 to 95% or less, the thickness t of the fixing pad 63 on the virtual straight line 120 is increased. It can be secured to effectively prevent cracking or tearing of the fixing pad 63.

FIG. 7 is a diagram for explaining how heat is transferred in the fixing device. With reference to FIG. 7, the heat of the fixing belt 61 heated by the heating source 62 is transmitted not only to the recording medium 110 side but also to the fixing pad 63 side. In this case, heat is transferred from the fixing belt 61 to the support member 66 through the fixing pad 63, and the power consumption in the heating source 62 increases.

With reference to FIGS. 3 to 6, in the fixing device 60 according to the present embodiment, the fixing pad 63 is provided with at least one of the first recess 81 and the second recess 91. ing. With such a configuration, the recess 80 functions as a heat insulating layer on the virtual straight line 120 on which the recess 80 extends, thereby suppressing heat conduction in the fixing pad 63. In this case, since the total length H of the recess 80 is equal to or greater than the thickness t of the fixing pad 63 on the virtual straight line 120, the heat insulating effect of the recess 80 can be efficiently enhanced. Further, since the volume of the fixing pad 63 is reduced by providing the recess 80, the effect of reducing the heat capacity of the fixing pad 63 is also obtained.

Further, the bottomed recess 80 (first recess 81, second recess 91) is provided between the first pad surface 71 and the second pad surface 72 in a non-penetrating manner. As a result, an air flow from the first pad surface 71 to the second pad surface 72 is generated along with the transportation of the recording medium 110 in the fixing nip portion N, and the heat transfer from the fixing belt 61 to the support member 66 is promoted. Can be prevented.

For the above reasons, it becomes difficult for heat to be transferred from the fixing belt 61 to the support member 66, so that the heat can be efficiently used by fixing the toner in the fixing nip portion N. As a result, it is possible to realize the image forming apparatus 1 having excellent energy saving by preventing the increase in power consumption in the heating source 62.

Further, the fixing pad 63 is provided with a first recess 81 that opens in the first pad surface 71 facing the fixing nip portion N. With such a configuration, heat is less likely to be transferred from the fixing belt 61 to the fixing pad 63, so that the efficiency of heat utilization in the fixing nip portion N can be further improved.

Further, the fixing pad 63 is provided with a plurality of first recesses 81 composed of only an air layer. With such a configuration, the heat insulating effect of the first recess 81 is enhanced, so that the heat utilization efficiency in the fixing nip portion N can be further improved.

Further, a sliding sheet 68 is provided so as to close the opening 83 of the first recess 81 on the surface 71 of the first pad. With such a configuration, a lubricant such as grease supplied to the fixing belt 61 may invade the first recess 81, or a wear piece or the like of the fixing belt 61 or the fixing pad 63 may invade the first recess 81. Can be prevented. As a result, it is possible to prevent a decrease in the heat insulating effect due to the intrusion of foreign matter such as a lubricant or a wear piece into the first recess 81.

FIG. 8 is a cross-sectional view schematically showing the mode of the fixing belt and the sliding sheet when the surface of the first pad has a convex surface. FIG. 9 is a cross-sectional view schematically showing the mode of the fixing belt and the sliding sheet when the surface of the first pad does not have a convex surface.

With reference to FIG. 8, the fixing pad 63 is provided with a plurality of first recesses 81 arranged side by side in a predetermined direction (left-right direction of the paper surface shown in FIG. 8). The first pad surface 71 has a convex surface 86 between the first recesses 81 adjacent to each other. The width Ln of the opening 83 of the first recess 81 in the predetermined direction is smaller than the width Lm of the convex surface 86 in the predetermined direction (Ln <Lm).

With reference to FIG. 9, the fixing pad 63 is provided with a plurality of first recesses 81 arranged side by side in a predetermined direction (left-right direction of the paper surface shown in FIG. 9). The first pad surface 71 has a corner portion 87 between the first recesses 81 adjacent to each other. The corner portion 87 has an edge shape at a tip protruding toward the fixing belt 61 and the sliding sheet 68. The corner portion 87 is in contact with the fixing belt 61 and the sliding sheet 68 on a line extending in the depth direction of the paper surface shown in FIG.

In the form of the first pad surface 71 shown in FIG. 9, since the fixing belt 61 and the sliding sheet 68 are only linearly supported by the corners 87, the fixing belt 61 and the sliding sheet 68 are the first. 1 There is a possibility of sinking inside the recess 81. In this case, the pressure distribution applied to the recording medium 110 in the fixing nip portion N becomes small in the region where the plurality of first recesses 81 are provided, so that the toner is locally poorly fixed (the glossiness is lowered in the color image). ) May occur.

On the other hand, in the form of the first pad surface 71 shown in FIG. 8, since the fixing belt 61 and the sliding sheet 68 are supported in a planar shape by the convex surface 86, the fixing belt 61 and the sliding sheet 68 are fixed to the inside of the first concave portion 81. The sinking of the belt 61 and the sliding sheet 68 can be suppressed. In addition, by making the opening width Ln of the first recess 81 smaller than the width Lm of the convex surface 86, the sinking of the fixing belt 61 and the sliding sheet 68 into the inside of the first recess 81 is more effectively suppressed. be able to. As a result, the pressure distribution applied to the recording medium 110 at the fixing nip portion N becomes more uniform, so that the toner can be fixed to the recording medium 110 with good quality.

In addition to the form of the fixing pad 63 described with reference to FIGS. 3 to 6, the fixing pad 63 has only the second recess 91 of the first recess 81 and the second recess 91 as the recess 80. It may be provided.

Summarizing the structures of the fixing device 60 and the image forming device 1 according to the first embodiment of the present invention described above, the fixing device 60 according to the present embodiment heats the endless fixing belt 61 and the fixing belt 61. The heating source 62, the fixing pad 63 arranged on the inner peripheral side of the fixing belt 61, the support member 66 supporting the fixing pad 63, and the fixing belt 61 are pressed toward the fixing pad 63, and the recording medium 110 is pressed. It is provided with a pressure roller 64 that forms the fixing nip portion N to be conveyed together with the fixing belt 61. The fixing pad 63 has a first pad surface 71 facing the fixing nip portion N, and a second pad surface 72 arranged on the back side of the first pad surface 71 and facing the support member 66. The fixing pad 63 has a bottomed first recess 81 that opens at the first pad surface 71 and is recessed toward the second pad surface 72, and a bottomed first recess 81 that opens at the second pad surface 72 and faces the first pad surface 71. At least one of the recesses 80 and the bottomed second recesses 91 that are recessed is provided. The recess 80 extends on a virtual straight line 120 extending between the first pad surface 71 and the second pad surface 72. When the length of the virtual straight line 120 between the first pad surface 71 and the second pad surface 72 is T and the total length of the recess 80 in the linear direction of the virtual straight line 120 is H, the total length H of the recess 80 is The thickness t (= TH) or more of the fixing pad 63 on the virtual straight line 120.

The image forming apparatus 1 in the present embodiment includes the fixing apparatus 60 described above.
According to the fixing device 60 and the image forming device 1 according to the first embodiment of the present invention configured in this way, heat is transferred from the fixing belt 61 by efficiently enhancing the heat insulating effect of the recess 80 in the fixing pad 63. It becomes difficult to transmit to the support member 66 through the fixing pad 63. As a result, the heat generated in the heating source 62 can be efficiently used by fixing the toner in the fixing nip portion N, and the energy saving property in the image forming apparatus 1 can be improved.

(Embodiment 2)
In this embodiment, various modifications of the fixing device 60 according to the first embodiment will be described. In the following, the description of the structure overlapping with the fixing device 60 in the first embodiment will not be repeated.

FIG. 10 is a top view showing a fixing pad of the fixing device in the first modification. FIG. 10 corresponds to FIG. 4 in the first embodiment.

With reference to FIG. 10, in this modified example, the fixing pad 63 is provided with a plurality of first recesses 81. The plurality of first recesses 81 are arranged at intervals from each other in the direction orthogonal to the transport direction of the recording medium 110 (the direction indicated by the arrow 107). The opening 83 formed by each of the first recesses 81 on the surface 71 of the first pad extends in a strip shape so that the transport direction of the recording medium 110 (the direction indicated by the arrow 106) is the longitudinal direction.

FIG. 11 is a top view showing a fixing pad of the fixing device in the second modification. FIG. 12 is a top view showing a fixing pad of the fixing device in the third modification. 11 and 12 correspond to FIG. 4 in the first embodiment.

With reference to FIGS. 11 and 12, in these modified examples, the fixing pad 63 is provided with a plurality of first recesses 81. The plurality of first recesses 81 are arranged at intervals from each other in the direction orthogonal to the transport direction of the recording medium 110 (the direction indicated by the arrow 107). The opening 83 formed by each of the first recesses 81 on the surface 71 of the first pad extends along an oblique direction with respect to the transport direction (direction indicated by the arrow 106) of the recording medium 110.

In the modified example shown in FIG. 11, the opening 83 formed by each of the first recesses 81 in the first pad surface 71 extends linearly along an oblique direction with respect to the transport direction of the recording medium 110. The angle formed by the stretching direction of the first recess 81 and the transporting direction of the recording medium 110 is preferably 15 ° or more. The angle formed by the stretching direction of the first recess 81 and the transporting direction of the recording medium 110 is, for example, 45 °.

In the modified example shown in FIG. 12, the opening 83 formed by each of the first recesses 81 in the first pad surface 71 extends while being curved along an oblique direction with respect to the transport direction of the recording medium 110. The opening 83 formed by each of the first recesses 81 on the surface 71 of the first pad extends in an S shape.

In the fixing pad 63 shown in FIG. 4 of the first embodiment, the opening 83 formed by each of the first recesses 81 on the surface 71 of the first pad extends in a direction orthogonal to the transport direction of the recording medium 110. In this case, when the fixing belt 61 passes through the fixing nip portion N, it enters the edge portion formed by the opening edge of the opening 83 from the front, so that an excessive force is applied from the fixing pad 63 to the fixing belt 61. there is a possibility. On the other hand, in the modified examples shown in FIGS. 11 and 12, since the opening 83 extends along an oblique direction with respect to the transport direction of the recording medium 110, the opening 83 is fixed from the edge portion formed by the opening edge of the opening 83. It is possible to prevent an excessive force from being applied to the belt 61. As a result, it is possible to effectively prevent the surface of the fixing belt 61 from being scratched or the fixing belt 61 from being damaged.

With reference to FIGS. 11 and 12, the first pad surface 71 has a plurality of convex surfaces 86. The plurality of convex surfaces 86 are arranged in a predetermined range 210 in a direction orthogonal to the transport direction of the recording medium 110. When an arbitrary straight line 202 extending along the transport direction of the recording medium 110 is projected onto the first pad surface 71, it is on the straight line 202 at all positions of the predetermined range 210 in the direction orthogonal to the transport direction of the recording medium 110. There is a convex surface 86 in at least a part of the surface.

A straight line 201P and a straight line 201Q extending along the transport direction of the recording medium 110 are projected on the surface 71 of the first pad in FIG. The straight line 201P extends so as to overlap the opening 83, and the straight line 201Q extends so as to overlap the convex surface 86. In such a configuration, when the recording medium 110 passes through the fixing nip portion N, it continuously passes through the position facing the opening 83 on the straight line 201P, so that the pressure distribution applied to the recording medium 110 is locally lowered. I will end up.

On the other hand, in the modification shown in FIGS. 11 and 12, the recording medium 110 passing through the fixing nip portion N has a convex surface 86 at least once over the entire range in the direction orthogonal to the transport direction of the recording medium 110. There is an opportunity to pass over. As a result, the pressure distribution applied to the recording medium 110 at the fixing nip portion N becomes more uniform, so that the toner can be fixed to the recording medium 110 with good quality.

FIG. 13 is a top view showing a fixing pad of the fixing device in the fourth modification. FIG. 14 is a top view showing a fixing pad of the fixing device in the fifth modification. 13 and 14 correspond to FIG. 4 in the first embodiment.

With reference to FIGS. 13 and 14, in these modified examples, the fixing pad 63 is provided with a plurality of first recesses 81. The plurality of first recesses 81 are arranged at intervals from each other in the direction orthogonal to the transport direction of the recording medium 110 in the fixing nip portion N (the direction indicated by the arrow 107). The opening 83 formed by each of the first recesses 81 on the surface 71 of the first pad extends along an oblique direction with respect to the transport direction of the recording medium 110 in the fixing nip portion N.

The plurality of first recesses 81 are provided so as to be symmetrically arranged on both sides of the center line 101 of the first pad surface 71 extending along the transport direction of the recording medium 110. If the first pad surface 71 is folded with the center line 101 as a bending line, a plurality of openings 83 that open in one area sandwiching the center line 101 and a plurality of openings that open in the other area sandwiching the center line 101. 83 overlaps with each other.

In the modified example shown in FIG. 13, the opening 83 of each first recess 81 on the surface 71 of the first pad extends so as to approach the center line 101 from the upstream side to the downstream side in the transport direction of the recording medium 110. There is. In the modified example shown in FIG. 14, the opening 83 of each first recess 81 on the first pad surface 71 extends so as to move away from the center line 101 from the upstream side to the downstream side in the transport direction of the recording medium 110. There is.

According to such a configuration, the pressure distribution applied to the recording medium 110 at the fixing nip portion N can be made more even on both sides of the center line 101 of the first pad surface 71. Thereby, the meandering of the recording medium 110 in the fixing nip portion N can be suppressed, and the uneven distribution of the lubricant such as grease supplied to the fixing belt 61 can be suppressed.

Further, the lubricant such as grease supplied to the fixing belt 61 may move along the opening 83 of the first recess 81 on the first pad surface 71. Even in such a case, in the modified example shown in FIG. 13, the opening 83 of the first recess 81 extends so as to approach the center line 101 from the upstream side to the downstream side in the transport direction of the recording medium 110. Therefore, the lubricant moves toward the center side of the first pad surface 71 in the direction orthogonal to the transport direction of the recording medium 110. As a result, the outflow of the lubricant can be suppressed.

FIG. 15 is a top view showing a fixing pad of the fixing device in the sixth modification. FIG. 16 is a top view showing a fixing pad in the range surrounded by the alternate long and short dash line XVI in FIG. FIG. 17 is a top view showing a fixing pad of the fixing device in the seventh modification. FIG. 18 is a top view showing the fixing pad in the range surrounded by the alternate long and short dash line XVIII in FIG. 15 and 17 correspond to FIG. 4 in the first embodiment.

With reference to FIGS. 15 to 18, in these modified examples, the fixing pad 63 is provided with a plurality of first recesses 81. The plurality of first recesses 81 are arranged at intervals from each other in the transport direction of the recording medium 110 (the direction indicated by the arrow 106) and the direction orthogonal to the transport direction of the recording medium 110 (the direction indicated by the arrow 107). I'm out. The plurality of first recesses 81 are arranged in a staggered pattern along the transport direction of the recording medium 110. The plurality of first recesses 81 are arranged in a staggered pattern along a direction orthogonal to the transport direction of the recording medium 110.

In the modified example shown in FIG. 15, the first recess 81 forms a quadrangular (diamond) opening 83 on the surface 71 of the first pad. In the modified example shown in FIG. 17, the first recess 81 forms a circular opening 83 on the surface 71 of the first pad.

The first pad surface 71 has a plurality of convex surfaces 86. The plurality of convex surfaces 86 are arranged in a predetermined range 210 in a direction orthogonal to the transport direction of the recording medium 110. When an arbitrary straight line 202 extending along the transport direction of the recording medium 110 is projected onto the first pad surface 71, it is on the straight line 202 at all positions of the predetermined range 210 in the direction orthogonal to the transport direction of the recording medium 110. There is a convex surface 86 in at least a part of the surface.

In FIGS. 16 and 18, a straight line 202P, a straight line 202Q, a straight line 202R, a straight line 202S, and a straight line 202T extending along the transport direction of the recording medium 110 are projected on the surface 71 of the first pad. In the modified example shown in FIG. 16, there are two convex surfaces 86 on the straight line 202P, four convex surfaces 86 on the straight line 202Q, and one convex surface 86 on the straight line 202R. , Four convex surfaces 86 exist on the straight line 202S, and two convex surfaces 86 exist on the straight line 202T. In the modified example shown in FIG. 18, two convex surfaces 86 exist on the straight line 202P, three convex surfaces 86 exist on the straight line 202Q, and one convex surface 86 exists on the straight line 202R. , Three convex surfaces 86 exist on the straight line 202S, and two convex surfaces 86 exist on the straight line 202T.

With such a configuration, the recording medium 110 passing through the fixing nip portion N has an opportunity to pass on the convex surface 86 at least once over the entire range in the direction orthogonal to the transport direction of the recording medium 110. As a result, the pressure distribution applied to the recording medium 110 at the fixing nip portion N becomes more uniform, so that the toner can be fixed to the recording medium 110 with good quality.

FIG. 19 is a cross-sectional view showing a fixing pad of the fixing device in the eighth modification. With reference to FIG. 19, in this modification, the fixing pad 63 is provided with a plurality of first recesses 81. In each of the first recesses 81, the area of the opening of the first recess 81 obtained when the fixing pad 63 is cut by a plane orthogonal to the depth direction of the first recess 81 is from the surface 71 of the first pad to the second pad. It is provided so that it becomes smaller as it approaches the surface 72.

According to such a configuration, by providing the side wall 89 of the first recess 81 with an inclination, the fixing pad 63 receiving the force from the pressure roller 64 is less likely to buckle. Thereby, the fixing pad 63 can be effectively prevented from being damaged.

FIG. 20 is a cross-sectional view showing a fixing device in the ninth modification. FIG. 20 corresponds to FIG. 3 in the first embodiment.

With reference to FIG. 20, in this modification, the fixing pad 63 is further provided with a bottomed third recess 84. The third recess 84 opens at the third pad surface 73 and is recessed toward the second pad surface 72.

The fixing pad 63 is provided with a plurality of third recesses 84 (84A, 84B). The third recess 84A is open to the third pad surface 73u arranged on the upstream side of the recording medium 110 in the transport direction with respect to the first pad surface 71. The third recess 84B is open to the third pad surface 73d arranged on the downstream side of the recording medium 110 in the transport direction with respect to the first pad surface 71. The depth of the third recess 84 is not particularly limited.

According to such a configuration, by additionally providing the fixing pad 63 with the plurality of third recesses 84, it becomes more difficult for heat to be transferred from the fixing belt 61 to the support member 66 through the fixing pad 63. Thereby, the utilization efficiency of the heat generated in the heating source 62 can be further improved.

FIG. 21 is a cross-sectional view showing a fixing device in the tenth modification. FIG. 22 is a cross-sectional view showing a fixing device in the eleventh modification. 21 and 22 correspond to FIG. 6 in the first embodiment.

With reference to FIG. 21, in this modification, the fixing pad 63 is provided with a plurality of first recesses 81 and a plurality of second recesses 91 as recesses 80. The fixing pad 63 is provided with two sets of recesses 80. Each set of recesses 80 is composed of four first recesses 81 and one second recess 91.

In each set of recesses 80, each of the four first recesses 81 and the second recess 91 extend on a virtual straight line 120 extending between the first pad surface 71 and the second pad surface 72. The length of the virtual straight line 120 between the first pad surface 71 and the second pad surface 72 is T, and the total length of the recess 80 (first recess 81, second recess 91) in the linear direction of the virtual straight line 120 is H ( = H1 + H2), the total length H of the recess 80 (first recess 81, second recess 91) is equal to or greater than the thickness t (= T-H1-H2) of the fixing pad 63 on the virtual straight line 120.

In addition to the recess 80 described above, the fixing pad 63 is further provided with a plurality of fourth recesses 96. The fourth recess 96 is open to the surface 71 of the first pad and is recessed toward the surface 72 of the second pad. The fourth recess 96 is provided at a position deviated from the second recess 91 in the transport direction of the recording medium 110.

With reference to FIG. 22, in this modification, the fixing pad 63 is provided with a plurality of first recesses 81X, a plurality of first recesses 81Y, and a plurality of second recesses 91 as recesses 80.

Similar to the modification shown in FIG. 21, two sets of recesses 80 including four first recesses 81X and one second recess 91 are provided. Each of the four first recesses 81 and the second recess 91 extend on a virtual straight line 120X extending between the first pad surface 71 and the second pad surface 72. The length of the virtual straight line 120X between the first pad surface 71 and the second pad surface 72 is T, and the total length of the recess 80 (first recess 81X, second recess 91) in the linear direction of the virtual straight line 120X is Hx ( = Hx1 + Hx2), the total length Hx of the recess 80 (first recess 81X, second recess 91) is equal to or greater than the thickness tx (= T-Hx1-Hx2) of the fixing pad 63 on the virtual straight line 120X.

The first recess 81Y is provided at a position deviated from the second recess 91 in the transport direction of the recording medium 110. Each of the plurality of first recesses 81Y constitutes a recess 80. The first recess 81Y extends on a virtual straight line 120Y extending between the first pad surface 71 and the second pad surface 72. When the length of the virtual straight line 120Y between the first pad surface 71 and the second pad surface 72 is T and the total length of the recess 80 (first recess 81Y) in the linear direction of the virtual straight line 120Y is Hy, the recess The total length Hy of the 80 (first recess 81Y) is equal to or greater than the thickness ty (= T-Hy) of the fixing pad 63 on the virtual straight line 120Y.

The depth of the first recess 81Y recessed from the first pad surface 71 is larger than the depth of the first recess 81X recessed from the first pad surface 71. The first recess 81Y is recessed from the surface 71 of the first pad to a depth that overlaps with the second recess 91.

According to the fixing device according to the second embodiment of the present invention described above, the effect described in the first embodiment can be similarly achieved.

It should be considered that the embodiments disclosed this time are exemplary in all respects and not restrictive. The scope of the present invention is shown by the scope of claims rather than the above description, and it is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

The present invention applies to fixing devices and image forming devices.

1 image forming device, 10 image reader, 11 automatic document feeding device, 12 document image scanning device, 12a sensor, 21 intermediate transfer belt, 23 secondary transfer unit, 30 image processing unit, 33 secondary transfer roller, 40 images Forming unit, 41, 41C, 41K, 41M, 41Y Image forming unit, 42 intermediate transfer unit, 50 transport unit, 51 paper feed unit, 51a, 51b, 51c paper feed tray unit, 52 paper discharge unit, 52a transport roller pair, 53 Transport path, 53a Resist roller pair, 60 Fixing device, 61 Fixing belt, 62 Heating source, 63 Fixing pad, 64 Pressurizing roller, 66 Support member, 67 Heating roller, 68 Sliding sheet, 71 First pad surface, 71J 1st region, 71K 2nd region, 72 2nd pad surface, 73, 73d, 73u 3rd pad surface, 76 support surface, 80 recesses, 81, 81A, 81B, 81C, 81D, 81X, 81Y 1st recesses, 82,92 bottom, 83,93 openings, 84,84A, 84B third recess, 86 convex, 87 corners, 89 side walls, 91,91A, 91B, 91C, 91D second recess, 96 fourth recess, 101 centerline , 110 recording medium, 120, 120A, 120B, 120C, 120D, 120X, 120Y virtual straight line, 201P, 201Q, 202, 202P, 202Q, 202R, 202S, 202T straight line, 210 predetermined range, 411 exposure device, 412 developing device, 413 Photoreceptor drum, 414 Charging device, 415 Drum cleaning device, 422, 422K primary transfer roller, 423 support roller, 423A roller, 426 belt cleaning device.

Claims (14)

With an endless fixing belt,
A heating source for heating the fixing belt and
A fixing pad arranged on the inner peripheral side of the fixing belt and
A support member that supports the fixing pad and
It is provided with a pressure roller that presses the fixing belt toward the fixing pad to form a fixing nip portion through which the recording medium is conveyed together with the fixing belt.
The fixing pad has a first pad surface facing the fixing nip portion and a second pad surface arranged on the back side of the first pad surface and facing the support member.
The fixing pad has a bottomed first recess that opens on the surface of the first pad and dents toward the surface of the second pad, and a bottomed first recess that opens on the surface of the second pad and dents toward the surface of the first pad. At least one of the bottomed second recesses is provided.
The recess extends on a virtual straight line extending between the surface of the first pad and the surface of the second pad.
When the length of the virtual straight line between the surface of the first pad and the surface of the second pad is T and the total length of the recess in the linear direction of the virtual straight line is H, the total length H of the recess is: A fixing device having a thickness t (= TH) or more of the fixing pad on the virtual straight line. The fixing device according to claim 1, wherein the fixing pad is provided with at least the first recess. The fixing device according to claim 2, wherein the fixing pad is provided with a plurality of the first recesses. The fixing device according to claim 3, wherein the surface of the first pad is arranged between the first recesses adjacent to each other and has a convex surface extending along the fixing belt. The plurality of convex surfaces are arranged in a predetermined range in a direction orthogonal to the transport direction of the recording medium.
When an arbitrary straight line extending along the transport direction of the recording medium is projected onto the surface of the first pad, at least one of the straight lines at all positions in the predetermined range in the direction orthogonal to the transport direction of the recording medium. The fixing device according to claim 4, wherein the convex surface is present in the portion. The plurality of first recesses are arranged at intervals in a direction orthogonal to the transport direction of the recording medium, and the openings of the first recesses on the surface of the first pad are oblique directions with respect to the transport direction of the recording medium. The fixing device according to claim 4 or 5, which extends along the same. The opening of each of the first recesses on the surface of the first pad approaches the center line of the surface of the first pad extending along the transport direction of the recording medium from the upstream side to the downstream side in the transport direction of the recording medium. The fixing device according to claim 6, which extends to. The plurality of first recesses are provided side by side in a predetermined direction.
The fixing device according to any one of claims 4 to 7, wherein the opening width of the first concave portion in the predetermined direction is smaller than the width of the convex surface in the predetermined direction. The first recess is provided so as to be symmetrically arranged on both sides of the center line of the surface of the first pad extending along the transport direction of the recording medium, according to any one of claims 2 to 8. Fixing device. The fixing device according to any one of claims 2 to 9, further comprising a sliding sheet provided so as to cover the surface of the first pad and closing the opening of the first recess on the surface of the first pad. The fixing according to any one of claims 2 to 10, wherein the first recess is provided so that the opening area of the first recess becomes smaller as the opening area of the first recess approaches the surface of the second pad. Device. The fixing device according to any one of claims 1 to 11, wherein only an air layer is provided inside the recess. The fixing pad further has a third pad surface arranged on the upstream side and the downstream side in the transport direction of the recording medium with respect to the first pad surface.
The fixing device according to any one of claims 1 to 12, wherein the fixing pad is further provided with a bottomed third recess that opens on the surface of the third pad and is recessed toward the surface of the second pad. .. An image forming apparatus comprising the fixing apparatus according to any one of claims 1 to 13.

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