JP2013064916A - Flexible member and image heating device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flexible member capable of suppressing abrasion of a support member that supports a heating body or abrasion of a surface of the flexible member in contact with the heating body and the support member.SOLUTION: A flexible member 30, which moves together with a recording material P carrying an image t while the member is in contact with the recording material, includes a base layer 30a that is in contact with a heating body 32 and a support member 31 supporting the heating body, on the side opposite to the side in contact with the recording material. The surface of the base layer in contact with the heating body and the support member includes a smooth flat surface portion 30a1 and a plurality of independent recesses 30a2 formed in the smooth flat surface portion.

Description

  The present invention provides a flexible member suitable for use as a fixing film of a fixing device (fixing device) mounted on an image forming apparatus such as an electrophotographic copying machine or an electrophotographic printer, and image heating provided with the flexible member. Relates to the device.

  2. Description of the Related Art A film heating type is known as a fixing device (fixing device) mounted on an electrophotographic copying machine or printer. This film heating type fixing device includes a heater having an energizing heating element on a ceramic substrate, a cylindrical fixing film that moves while contacting the heater, and a heater that forms a nip portion with the fixing film sandwiched between the heater and the heater. It has a pressure roller. The recording material carrying the unfixed toner image is nipped and conveyed at the nip portion, whereby the toner image on the recording material is heated and fixed to the recording material.

  This type of fixing device has an advantage that the time for starting energization of the heater and raising the temperature to the fixable temperature is short. Therefore, a printer equipped with this fixing device can shorten the time (FPOT: First Print Out Time) from when a print command is input until the first image is output. This type of fixing device also has an advantage that power consumption during standby for waiting for a print command is small.

  In the film heating type fixing device, the contact surface between the heater and the fixing film is pressed and slid in a close contact state at the nip portion, and the sliding resistance becomes a driving load. In order to reduce this driving load, it is very important to reduce the dynamic frictional resistance between the inner peripheral surface (inner surface) of the fixing film and the heater. For this reason, a sliding property between the inner surface of the fixing film and the heater is ensured by interposing a lubricant such as heat-resistant grease between the inner surface of the fixing film and the heater.

  In recent years, with the demand for colorization and the demand for productivity improvement, the fixing film of the fixing device is often used in a higher temperature and higher pressure environment. As a result, if you continue to use the fixing device, the stress on the sliding surface between the inner surface of the fixing film and the heater will cause the inner surface of the fixing film to wear and the viscosity of the lubricating grease to deteriorate, and the sliding resistance of the fixing film will likely increase. It has become.

  As a result, a slip that temporarily stops the fixing film may occur, and an image defect due to the slip may occur. Further, when the frequency of occurrence of slip increases, a jam that prevents the recording material from being conveyed may occur.

  Even when slip does not occur, especially when the fixing device is operated at a low speed and high temperature, a phenomenon called stick slip that periodically repeats slight stops and sliding between the fixing film and the heater. May occur and chatter noise may occur. In particular, in the case of a color printer that requires high glossiness on the toner surface after fixing, the stick-slip is likely to occur because heat fixing is performed under a high pressure. That is, the life of the fixing device is shortened.

  In order to cope with this problem, the amount of lubricant retained is increased by roughening the inner surface of the film member, and further, the contact area between the heater or the heater holder and the film member is reduced, and the frictional resistance is reduced. (See Patent Document 1 and Patent Document 2).

JP 2001-341143 A JP 2003-233264 A

  However, when the film member having the roughened inner surface is used as a fixing film, there are the following problems.

  The inner surface of the roughened fixing film contacts the heater and the heater holder that supports the heater. The fixing film with the roughened inner surface described above may have a portion of the heater holder that contacts the fixing film or the inner surface of the fixing film when sliding with the heater and the heater holder.

  As a result, even if the contact area between the folding heater or the heater holder and the fixing film is reduced and the frictional resistance is reduced, the sliding resistance of the fixing film increases due to scraping powder by continuing to use the fixing device. The present inventors have found that when the sliding resistance of the fixing film increases as described above, the fixing film slip and stick slip are induced, and the life of the fixing device cannot be effectively extended.

  This is because the fixing film whose inner surface is roughened has a point contact at the micro-contact surface between the heater and the heater holder, so that the contact surface pressure increases. For this reason, it is considered that stress on the contact surface of the inner surface of the fixing film with the heater holder increases, and the inner surface of the heater holder and the fixing film is scraped off. In addition, the fixing film whose inner surface is roughened moves while the unevenness of the inner surface of the fixing film and the heater holder are engaged with each other on the micro contact surface between the heater and the heater holder. For this reason, it is considered that the stress increases in the portion where the unevenness of each other is engaged, and the heater holder and the inner surface of the fixing film are scraped off.

  In addition, when the above-mentioned shaving powder is generated on the heater holder or the inner surface of the fixing film, the shaving powder and the solid component of the heat-resistant grease are fixed on the heater, and fixing unevenness may occur at the portion where the solid component is fixed. is there. As a result, glossy uneven streaks are introduced in the transport direction in the recorded image, which may impair the image quality.

  An object of the present invention is to provide a support member that supports a heating body, a flexible member that can suppress scraping of a surface that contacts the heating body and the support member, and an image heating apparatus including the flexible member. There is to do.

  The configuration of the flexible member according to the present invention for achieving the above object is a flexible member that contacts the recording material carrying an image and moves together with the recording material, and is opposite to the side in contact with the recording material. A flexible member having a base layer made of a heat-resistant resin that comes into contact with the heating body and a support member that supports the heating body, wherein the surface of the base layer that contacts the heating body and the support member is a smooth flat portion And a plurality of independent recesses formed in the smooth flat surface portion.

  In order to achieve the above object, the image heating apparatus according to the present invention comprises a heating member, a supporting member that supports the heating member, and a flexible member that moves together with the recording material in contact with the recording material that carries the image. A flexible member having a base layer made of a heat-resistant resin in contact with the heating body and the support member on a side opposite to the side in contact with the recording material, and the flexible member for the heating body and the support An image heating apparatus that heats an image while sandwiching and transporting a recording material that carries an image at the nip portion, and a heating member for the base layer and the support. The surface in contact with the member has a smooth flat portion and a plurality of independent concave portions formed in the smooth flat portion.

  According to the present invention, there are provided a support member that supports the heating body, a flexible member that can suppress scraping of a surface that contacts the heating body and the support member, and an image heating apparatus including the flexible member. can do.

FIG. 2A is a schematic configuration diagram from a transverse side surface of the fixing device according to the first exemplary embodiment. FIG. 4B is a cross-sectional view illustrating a layer configuration of a fixing film of the fixing device. 1 is an exploded perspective view of a fixing device according to Embodiment 1. FIG. FIG. 2 is a schematic configuration diagram from a vertical side surface of the fixing device according to the first exemplary embodiment. (A) is the one part enlarged schematic view from the heater side of the base layer inner surface of the fixing film which concerns on Example 1, (b) is sectional drawing of the base layer inner surface of the fixing film shown to (a). (A) is a schematic diagram showing a state in which the inner surface of the base layer of the roughened fixing film as a conventional example is rubbed against the surface of the downstream jaw portion of the heater holder in the fixing device at the start of use (new article). (B) is a schematic diagram showing a state in which the inner surface of the base layer of the roughened fixing film as a conventional example is in sliding contact with the surface of the downstream jaw portion of the heater holder in the fixing device that has been used. (A) is a schematic diagram showing a state in which the inner surface of the base layer of the fixing film of this embodiment is in sliding contact with the downstream jaw surface of the heater holder in the fixing device at the start of use (new article). (B) is a schematic diagram showing a state in which the inner surface of the base layer of the fixing film of this example is in sliding contact with the surface of the downstream jaw portion of the heater holder in the fixing device that has been used. (A) is a schematic diagram showing a state in which the inner surface of the base layer of the roughened fixing film as a conventional example is rubbed against the surface of the glass coat layer of the heater in the fixing device at the start of use (new article). (B) is a schematic view showing a state in which the inner surface of the base layer of the roughened fixing film as a conventional example is rubbed against the surface of the glass coat layer of the heater in the fixing device that has been used. (A) is a schematic diagram showing a state in which the inner surface of the base layer of the fixing film of this example is rubbed against the surface of the glass coat layer of the heater in the fixing device at the start of use (new article). (B) is a schematic diagram showing a state in which the inner surface of the base layer of the fixing film of this example is rubbed against the surface of the glass coat layer of the heater in the fixing device that has been used. FIG. 7 is an explanatory diagram of an example of the inner surface of the base layer of the fixing film according to Example 2, and is a partial enlarged schematic view from the heater side of the inner surface of the base layer of the fixing film of Example 2-1. It is explanatory drawing of an example of the base layer inner surface of the fixing film which concerns on Example 2, Comprising: It is the one part enlarged schematic diagram from the heater side of the base layer inner surface of the fixing film of Example 2-2. FIG. 6 is an explanatory diagram of an example of the inner surface of the base layer of the fixing film according to Example 2, and is a partial enlarged schematic view from the heater side of the inner surface of the base layer of the fixing film of Example 2-3. FIG. 10 is an explanatory diagram of an example of the inner surface of the base layer of the fixing film according to Example 2, and is a partial enlarged schematic view from the heater side of the inner surface of the base layer of the fixing film of Example 2-4. FIG. 10 is an explanatory diagram of an example of the inner surface of the base layer of the fixing film according to Example 2, and is a partial enlarged schematic view from the heater side of the inner surface of the base layer of the fixing film of Example 2-5.

  Exemplary embodiments of the present invention will be described in detail below with reference to the drawings. However, the dimensions, materials, shapes, and relative arrangements of the components described in this embodiment should be appropriately changed according to the configuration of the apparatus to which the invention is applied and various conditions. It is not intended to limit the scope to the following embodiments.

[Example 1]
An embodiment of an image heating apparatus according to the present invention will be described in detail with reference to FIGS. The image heating apparatus shown in this embodiment is suitable for use as a film heating type fixing apparatus mounted on an image forming apparatus such as an electrophotographic copying machine or a printer.

  In the following description, regarding the fixing device and the members constituting the fixing device, the longitudinal direction means a direction orthogonal to the recording material conveyance direction on the surface of the recording material. The short side direction is a direction parallel to the recording material conveyance direction on the surface of the recording material. The length is a dimension in the longitudinal direction. The width is a dimension in the short direction.

  1A is a schematic configuration diagram from a transverse side surface of the fixing device F according to the first embodiment, and FIG. 1B is a cross-sectional view illustrating a layer configuration of a fixing film 30 of the fixing device F. FIG. 2 is an exploded perspective view of the fixing device F. FIG. FIG. 3 is a schematic diagram of a schematic configuration of the fixing device F as viewed from the longitudinal side.

  The fixing device F is a tensionless type film heating type device. The tensionless type film heating type fixing device F uses an endless belt (or cylindrical) heat-resistant film as an endless belt (or cylindrical). At least a part of the circumference of the heat resistant film is always tension free (a state in which no tension is applied), and the heat resistant film is driven to rotate by the rotational driving force of the pressure roller.

  The fixing device F shown in this embodiment is roughly divided into a film assembly unit 50 and a pressure roller (backup member) 33. The film assembly unit 50 includes a fixing film (flexible member) 30, a ceramic heater (heating member) 32, a rigid stay (reinforcing member) 34, a heater holder (supporting member) 31, and a regulating flange (regulating member) 36. Etc. The fixing film 30, the ceramic heater (hereinafter referred to as a heater) 32, the rigid stay 34, the heater holder 31, and the pressure roller 33 are all members that are long in the longitudinal direction.

  The configuration of the film assembly unit 50 and the pressure roller 33 will be described with reference to FIGS. The heater holder 31 is formed so that the cross-sectional shape is substantially bowl-shaped. A rigid stay 34 is disposed along the longitudinal direction on the upper surface of the center of the heater holder 31 in the short direction. A heater receiving groove 31a is provided on the lower surface of the center of the heater holder 31 in the short direction along the longitudinal direction. The heater 32 is fitted and supported in the heater receiving groove 31a. A thermistor (temperature detection member) 41 (see FIG. 1A) is supported on the lower surface of the center of the heater holder 31 in the short direction. The thermistor 41 is disposed at a position where it contacts the heater 32 when the heater 32 is supported by the heater receiving groove 31a.

  A cylindrical (tubular) fixing film 30 is loosely fitted on the heater holder 31 to which the rigid stay 34, the heater 32, and the thermistor 41 are assembled. Overhang portions 34 a provided at both ends in the longitudinal direction of the rigid stay 34 protrude from the end surfaces at both ends in the longitudinal direction of the fixing film 30. A regulation flange 36 is fitted to each of the overhang portions 34a.

  The restriction flange 36 is configured to restrict movement in the longitudinal direction of the fixing film 30 that rotates around the outer periphery of the heater holder 31 by a restriction surface 36 a that faces the end in the longitudinal direction of the fixing film 30. The two restriction flanges 36 are disposed such that the distance between the restriction surfaces 36 a of the restriction flange 36 is longer than the length of the fixing film 30. This is because the longitudinal end portion of the fixing film 30 is not damaged during normal use of the fixing device F (during the heat fixing operation).

  Further, the length of the pressure roller 33 is about 10 mm shorter than the fixing film 30. This is to prevent the grease protruding from the end in the longitudinal direction of the fixing film 30 from coming into contact with the outer peripheral surface (surface) of the pressure roller 33 and losing the gripping force to cause the fixing film 30 to slip.

  In the heater 32, both end portions in the longitudinal direction including the power supply terminal 32 d protrude outward from the restriction flange 36. A concave-shaped heater connector 35 having metal contacts inside is attached to both ends in the longitudinal direction of the heater 32, and the heater connector 35 and the power supply terminal 32d are brought into electrical contact to provide a power supply path to the heater 32. I'm making it.

  In the present embodiment, as described above, the film assembly unit 50 is configured by integrally assembling the fixing film 30, the heater 32, the rigid stay 34, the heater holder 31, the restriction flange 36, the thermistor 41, and the like. ing. In the film assembly unit 50, the movement of the film assembly unit in the longitudinal direction is restricted, and the top plate side that constitutes a part of the apparatus frame of the fixing device F so that the film assembly unit can be moved in the vertical direction. It is supported by a housing 39 (see FIG. 3). On the other hand, the pressure roller 33 is disposed below the film assembly unit 50 and is rotatably supported by a bottom housing 40 (see FIG. 3) that constitutes a part of the apparatus frame of the fixing device F.

  Pressurizing springs 38 are attached in a compressed state to spring support portions 39a projecting downward from both longitudinal ends of the top plate side casing 39, respectively. The pressing force of the pressure spring 38 is received by the protruding portion 34 a of the rigid stay 34 in the film assembly unit 50. As a result, the rigid stay 34 is pressed toward the pressure roller 33, and the entire film assembly unit 50 is pressed toward the pressure roller 33.

  A bearing 37 is provided on each of the bearing support portions 40 a projecting upward from both longitudinal ends of the bottom housing 40, and the bearing 37 is used to apply a pressing force from the film assembly unit 50 via the pressure roller 33. I take it. Since the bearing 37 rotatably supports a later-described cored bar 33a of the pressure roller 33 that becomes relatively high in temperature, the bearing 37 is made of a material that has heat resistance and excellent slidability.

  Each member will be described in more detail.

  The heater 32 has an elongated heater substrate (hereinafter referred to as a substrate) 32a made of ceramic having high heat resistance. On the surface of the substrate 32a (surface on which a fixing nip portion N side described later is formed), a resistance heating element 32b that generates heat by energization and a power supply electrode (not shown) are printed in a pattern. The resistance heating element 32b is formed along the longitudinal direction of the substrate 32a. The power feeding electrodes are disposed at both ends in the longitudinal direction of the resistance heating element 32b and are electrically connected to the power feeding terminal 32d.

  Furthermore, a glass coat layer 32c is provided on the surface of the substrate 32a as a protective layer for protecting the resistance heating element 32b so as to cover the resistance heating element 32b. The glass coat layer 32 c is disposed on the surface side of the heater 32, that is, the side in contact with the inner peripheral surface (inner surface) of the fixing film 30. The glass coat layer 32c is generally harder than the fixing film 30, and if the unevenness of the surface of the glass coat layer 32c that contacts the inner surface of the fixing film 30 is large, the inner surface of the fixing film is scraped and slips on the fixing film (also referred to as fixing slip). Is likely to occur. Therefore, the surface of the glass coat layer 32c is processed into a smooth surface as close to a mirror surface as possible.

  A thermistor 41, which is a temperature detection element, is in contact with the back surface of the substrate 32a of the heater 32 (the surface opposite to the side on which a fixing nip portion N described later is formed). An output signal (detected temperature signal) of the thermistor 41 is input to a control unit (control means) (not shown) including a CPU and a memory such as a RAM and a ROM.

  The heater holder 31 supports the heater 32 and guides the rotation of the fixing film 30. As a material of the heater holder 31, a high heat resistant resin such as polyimide, polyamideimide, PEEK, PPS, liquid crystal polymer, or a composite material of these resins with ceramics, metal, glass, or the like can be suitably used. Among these materials, a liquid crystal polymer that has a high heat-resistant temperature, can be molded, and has excellent dimensional stability can be particularly preferably used.

  Liquid crystal polymers have the following advantages. First, since the heat-resistant temperature is high, the degree of freedom of the set temperature (target temperature) of the heater 32 can be increased. In addition, since it can be molded, productivity is high and mass production is possible. Further, since the dimensional stability is excellent, there is an advantage that the pressing force to the pressure roller 30 can be made uniform in the longitudinal direction and the recording material conveyance performance is stabilized.

  The rigid stay 34 is made of a metal such as iron, and is a member that maintains strength so as not to be greatly deformed even by a pressure that presses the heater holder 31 toward the pressure roller 30.

  The pressure roller 33 includes a metal round shaft-shaped cored bar 33a, an elastic layer 33b provided in a roller shape on the outer peripheral surface between supported portions at both ends in the longitudinal direction of the cored bar 33a, and an elastic layer 33b. It has a release layer 33c provided on the outer peripheral surface. Silicone rubber having elasticity is used as the elastic layer 33b. The pressure roller 33 is disposed below the fixing film 30 so that the outer peripheral surface of the release layer 33 c (hereinafter referred to as the surface of the pressure roller 33) faces the heater 32 through the surface of the fixing film 30. is there.

  With the pressing force from the film assembly unit 50 against the pressure roller 33, the surface of the fixing film 30 is brought into contact with the surface of the pressure roller 33 by the heater 32 and the heater holder 31 to press the elastic layer 33 b of the pressure roller 33. It is elastically deformed in the radial direction. Accordingly, a fixing nip portion (nip portion) N having a predetermined width is formed by the surface of the fixing film 30 and the surface of the pressure roller 33. That is, the pressure roller 33 forms the fixing nip portion N by sandwiching the fixing film 30 together with the heater 32 and the heater holder 31.

  With reference to FIG. 1A, the positional relationship between the film assembly unit 50 and the pressure roller 33 in the recording material conveyance direction will be described. A line Lfc passing through the center of the heater 32 in the short direction is set as the center line of the film assembly unit 50. A line passing through the rotation axis center of the pressure roller 33 and orthogonal to the surface of the substrate 32 a of the heater 32 is defined as a center line Lpc of the pressure roller 33. In this case, the film assembly unit 50 and the pressure roller 33 are disposed so that Lfc and Lpc do not overlap, and Lfc is positioned upstream of Lpc in the recording material conveyance direction.

  By adopting such a positional relationship, the members that support the fixing film 30 in the fixing nip portion N receiving the pressing force (pressure) from the film assembly unit 50 are the heater 32 and the heater holder 31. That is, the heater 32 and the heater holder 31 are in contact with the inner surface of the fixing film 30 at a relatively high pressure in the fixing nip portion N. Here, a contact portion that is in contact with the inner surface of the fixing film 30 of the heater holder 31, that is, a bent portion directly below the downstream side in the recording material conveyance direction from the heater receiving groove 31a of the heater holder 31 is referred to as a downstream jaw portion 31b.

  Curling when the recording material P is discharged can be corrected by making a place where the fixing film 30 is bent and pressed at the downstream jaw portion 31b of the heater holder 31. Furthermore, there is an effect of increasing the gloss by locally applying a high pressure to the toner surface on the recording material P that has been heated and pressurized on the upstream side of the fixing nip N together with the recording material P.

(2) Heat Fixing Operation of Fixing Device F The above-described control unit rotates the drive motor in response to a print command output from an external device such as a host computer. The rotation of the output shaft of the drive motor is transmitted to a drive gear 44 (see FIG. 3) provided at the longitudinal end of the shaft core 33a of the pressure roller 33, whereby the pressure roller 33 is predetermined in the arrow direction. It rotates at a peripheral speed (process speed) of.

  The rotation of the pressure roller 33 is transmitted to the surface of the fixing film 30 by the frictional force between the surface of the pressure roller 33 and the surface of the fixing film 30 in the fixing nip portion N. As a result, the fixing film 30 rotates in the direction of the arrow following the rotation of the pressure roller 33 while the inner surface of the fixing film 30 is in contact with the glass coat layer 32 c of the heater 32 and the downstream jaw portion 31 b of the heater holder 31. At this time, the inner surface of the fixing film 30 slides on the glass coat layer 32 c of the heater 32 and the downstream jaw portion 31 b of the heater holder 31 in the fixing nip portion N.

  In order to reduce the sliding resistance between the inner surface of the fixing film 30, the glass coat layer 32 c of the heater 32, and the downstream jaw portion 31 b of the heater holder 31 in the fixing nip N, the surface of the glass coat layer on the side in contact with the inner surface of the fixing film Grease is applied as a lubricant. Grease is a heat-resistant grease obtained by mixing and dispersing a fluorine oil and a fluororesin as a solid lubricant based on a fluorine oil as a liquid lubricant. Grease is interposed between the inner surface of the fixing film 30 and the glass coat layer 32c of the heater 32 so that good slidability of the fixing film 30 with respect to the heater holder 31 and the heater 32 can be maintained even when the fixing device F is used for a long time. ing.

  Further, the control unit turns on a triac (not shown) as an energization control unit in response to the print command. Thus, the triac supplies power to the power supply terminal 32 d of the heater 32 through the heater connector 35. The resistance heating element 32b is energized from the power supply terminal 32d through the power supply electrode. As a result, the heat generating resistor 32 b generates heat, and the heater 32 rapidly rises in temperature to heat the fixing film 30. The thermistor 41 detects the temperature of the heater 32, and the controller captures temperature information output from the thermistor 41. Based on the temperature information from the thermistor 41, the control unit controls the triac so that the temperature information of the heater 32 maintains a predetermined fixing temperature (target temperature).

  The recording material P carrying the toner image (image) t is fixed by the introduction guide 42 with the toner image carrying surface facing upward in a state where the pressure roller 33 is rotated and the temperature of the heater 32 is maintained at a predetermined fixing temperature. The sheet is fed (introduced) into the nip portion N. The recording material P is sandwiched between the surface of the fixing film 30 and the surface of the pressure roller 33 at the fixing nip portion N. Then, the surface of the fixing film 30 contacts the toner image carrying surface (surface) of the recording material P and rotates together with the recording material P. The pressure roller 33 rotates together with the recording material P while the surface of the pressure roller 33 comes into contact with the surface (back surface) opposite to the toner image carrying surface of the recording material P. Thereby, the recording material P is conveyed (clamped and conveyed) in a state of being sandwiched between the surface of the fixing film 30 and the surface of the pressure roller 33.

  In this conveying process, the toner image t is heated and fixed on the recording material by receiving the heat of the fixing film 30 and the pressure of the fixing nip portion N. The recording material P on which the toner image t has been heat-fixed is discharged from the fixing nip portion N while being separated from the surface of the fixing film 30.

(3) Layer structure of fixing film 30 and description of inner surface of base layer 30a FIG. 1 (b) shows the layer structure of the fixing film 30. The fixing film 30 shown in this embodiment includes an endless belt-like (or cylindrical) base layer 30a, an elastic layer 30b laminated on the outer peripheral surface of the base layer 30a, and a release layer laminated on the outer peripheral surface of the elastic layer 30b. It has a mold layer 30c and the like.

  The release layer 30 c is a layer for preventing an offset phenomenon that occurs when the toner once adheres to the surface of the fixing film 30 and moves to the recording material P again. As the release layer 30c, a fluororesin such as PFA, PTFE, FEP and the like having a good release property having a thickness of about 5 to 70 μm can be suitably used. In this embodiment, a uniform fluororesin layer is easily formed by using a PFA tube having a thickness of 15 μm.

  The elastic layer 30b is often used especially for a pressure roller of a fixing device mounted on a color image forming apparatus. The elastic layer 30b makes it possible to heat the toner image t so as to wrap the toner image t regardless of the unevenness of the surface of the recording material P (the toner image carrying surface of the recording material P). It makes it possible to obtain images. In this embodiment, a silicone rubber layer having a relatively high thermal conductivity is used as the elastic layer 30b. As a result, higher on-demand characteristics and better fixing performance can be obtained. Here, the higher on-demand property means that the time for starting energization of the heater and raising the temperature to the fixable temperature is shorter.

  The base layer 30 a is a layer that is disposed on the innermost surface side of the fixing film 30 and contacts the glass coat layer 32 c of the heater 32 and the downstream jaw portion 31 b of the heater holder 31. As the material of the base layer 30a, a heat-resistant and flexible high heat-resistant resin such as polyimide, polyamideimide, and PEEK is used, and the single layer is formed with a thickness of about 10 to 100 μm. In order to efficiently transfer the heat of the heater to the toner image t on the recording material P at the fixing nip N where the heater 32 and the pressure roller 33 face each other with the fixing film 30 interposed therebetween, the fixing film 30 is sufficient for the heater. It is important to have flexibility so that it can be closely attached.

  In order to improve the flexibility of the fixing film 30, it is effective to make the base layer 30a thinner. On the other hand, since the fixing film 30 maintains the mechanical strength by the base layer 30a, when the thickness of the base layer is extremely thin, the strength is lowered, the fixing film is deformed, and wrinkles are easily formed. The required strength cannot be obtained, for example, the end portion is likely to buckle. In order to prevent this, when the base layer 30a is polyimide, the thickness needs to be 10 μm or more. In this embodiment, a cylindrical polyimide resin having a thickness measured by a micrometer of 50 μm and an inner diameter of 18 mm is used as the base layer 30a.

  In the base layer 30a, the inner peripheral surface of the base layer 30a opposite to the elastic layer 30b (hereinafter referred to as the inner surface of the base layer 30a) is the surface on the fixing nip N side of the glass coat layer 32c of the heater 32 and downstream of the heater holder 31. This surface is in contact with the surface on the fixing nip portion N side of the jaw portion 31b. Accordingly, the inner surface of the base layer 30 a slides on the surfaces of the glass coat layer 32 c and the downstream jaw portion 31 b as the fixing film 30 rotates. In order to reduce the sliding resistance between the surface of the glass coat layer 32c on the inner surface of the base layer 30a and the surface of the downstream jaw portion 31b, grease is applied to the surface of the glass coat layer 32c.

  For the purpose of holding the grease and reducing the contact area between the surface of the glass coat layer 32c and the surface of the downstream jaw portion 31b, the inner surface of the base layer 30a is formed on the smooth flat portion 30a1 and the smooth flat portion 30a1. And a plurality of independent recesses 30a2. Thereby, the frictional resistance between the surface of the glass coat layer 32c on the inner surface of the base layer 30a and the surface of the downstream jaw portion 31b can be reduced.

  The shape of the plurality of concave portions 30a2 independent of the smooth flat surface portion 30a1 on the inner surface of the base layer 30a will be described with reference to FIG. 4A is a partially enlarged schematic view of the inner surface of the base layer 30a from the heater 32 side, and FIG. 4B is a cross-sectional view of the inner surface of the base layer 30a shown in FIG.

  In FIG. 4A, the inside of the frame line in the drawing shows a part of the inner surface of the base layer 30a of the fixing film 30, the white background portion is a smooth flat portion 30a1, and the black background portions are independent. Is a concave portion (hereinafter referred to as a plurality of concave portions) 30a2.

  The smooth flat surface portion 30a1 includes a plurality of convex-shaped protrusions 30a11 that remain between the plurality of recesses 30a2 after the plurality of recesses 30a2 are formed. In the plurality of projecting portions 30a11, the smooth surface 30a12 at the tip is in contact with the surface of the glass coat layer 32c and the surface of the downstream jaw portion 31b (surface contact). For this reason, the smooth flat surface portion 30a1 has a function as a reference flat surface serving as a sliding portion between the surface of the glass coat layer 32c and the surface of the downstream jaw portion 31b. Hereinafter, the smooth plane portion 30a1 is referred to as a convex plane portion 30a1.

  Each of the plurality of recesses 30a2 has an indefinite elliptical shape when viewed from the heater 32 side (see FIG. 4A). In this embodiment, the average outer diameter of the plurality of recesses 30a2 is about 350 μm. The grease is held between the plurality of recesses 30a2, and when the fixing device F is continuously used, the occurrence of slipping and stick slip of the fixing film 30 can be suppressed.

  In the inner surface of the base layer 30a, the abundance ratio of the convex flat portions 30a1 (hereinafter referred to as convex flat portion ratio), the surface roughness of the inner surface of the base layer 30a, and the shapes (depth and volume ratio) of the plurality of concave portions 30a2 are important. This will be described below.

  First, the convex plane part ratio (ratio occupied by the convex flat part 30a1 on the inner surface of the base layer 30a) will be described. If the convex plane area ratio is too large, the amount of grease retained will be small, and the effect of suppressing slipping and stick slip of the fixing film will be small or cannot be obtained when the fixing device is continuously used. For example, when the presence rate is 85%, the effect of suppressing slip and stick slip is hardly observed.

  On the contrary, if the convex flat area ratio is too small, the strength of the fixing film becomes weak, and when the fixing device is continuously used, the strength is lowered, the fixing film is deformed, and wrinkles are easily formed. Further, the end in the longitudinal direction tends to buckle, and the life of the fixing device is shortened. For example, when the existence ratio is 30%, the life of the fixing device is shortened.

  Therefore, in order to suppress the occurrence of slip and stick slip of the fixing film 30 and to maintain the strength of the fixing film 30 so that the fixing film 30 is not deformed, the convex plane area ratio is preferably 40 to 80%. In this embodiment, the convex flat portion ratio on the inner surface of the base layer 30a is 65%. About the convex plane part rate, the presence rate of the convex plane part 30a1 was calculated by image processing using the micrograph.

  Next, the surface roughness of the inner surface of the base layer 30a will be described below. In the inner surface of the base layer 30a, it is important that the surface roughness of the inner surface of the base layer 30a is small. This is because if the surface of the inner surface of the base layer 30a is rougher than a certain level, the portion will be scraped.

  Specifically, on the inner surface of the base layer 30a, when the protrusion peak height Rpk measured by the method according to JIS B0601: 2001 under the condition of the cutoff value λc = 0.8 mm exceeds 2 μm, The effect of suppressing scraping is small or cannot be obtained. In addition, the effect of suppressing shaving is small even when the maximum peak height Rzjis exceeds 3.5 μm, measured under the condition of the cutoff value λc = 0.1 mm by the method according to JIS B0601: 2001. Or you won't get it.

  For example, when the fixing film 30 having a protrusion peak height Rpk of 3 μm on the inner surface of the base layer 30a measured under the above measurement conditions is used, the effect of suppressing slip or stick slip is hardly observed. Similarly, when the fixing film 30 having a maximum peak height Rzjis of 5 μm on the inner surface of the base layer 30a measured under the above measurement conditions was used, almost no slip or stick slip suppression effect was observed.

  Accordingly, in order to obtain the effect of suppressing the slip or stick slip of the fixing film 30, the protrusion peak height Rpk on the inner surface of the base layer 30a is preferably 2 μm or less, or the maximum peak height Rzjis on the inner surface of the base layer 30a is preferably 3.5 μm or less.

  In the present embodiment, the fixing film 30 having a protrusion mountain height Rpk of 0.5 μm on the inner surface of the base layer 30a, measured under the condition of a cut-off value λc = 0.8 mm by a method according to JIS B0601: 2001. Used. In addition, the fixing film 30 having a maximum peak height Rzjis of 1.5 μm on the inner surface of the base layer 30a, which is measured under the condition of a cutoff value λc = 0.1 mm by a method based on JIS B0601: 2001, is used. For the measurement of the surface roughness, a contact-type surface roughness meter [manufactured by Kosaka Laboratory Ltd .: Surfcoder SE-3300] was used.

  Next, the shape (depth, volume ratio) of the plurality of recesses 30a2 will be described. In FIG. 4B, the hatched portion in the drawing shows a partial cross section on the inner surface side of the base layer 30a. The upper side in the figure is the inner surface side of the base layer 30a. That is, the portion protruding upward in the drawing is the convex flat portion 30a1, and the portion recessed in the lower side in the drawing is the plurality of concave portions 30a2. The average depth from the upper surface 30a12 of the protruding portion 30a11 of the convex flat portion 30a1 to the bottom surface 30a21 of the concave portion 30a2 is shown as z.

  First, the depth z will be described below. If the depth z is too large, the contact thermal resistance between the surface of the glass coat layer 32c and the inner surface of the base layer 30a increases, so that the heat conduction to the toner image t on the recording material P decreases. As a result, in the recorded image heat-fixed on the recording material, the glossiness of the image is lowered, or fixing failure due to insufficient heating of the toner tends to occur. For example, when the depth z is 15 μm, the glossiness of the image is reduced in the recorded image.

  On the other hand, if the depth z is too small, the grease cannot be held, and the effect of suppressing the slip and stick slip of the fixing film cannot be obtained when the fixing device is continuously used. This is considered due to the fact that the secondary aggregate particle diameter of the fluororesin powder, which is the solid content of grease, is about 2 μm. In other words, since it is not a recess that is large enough to fit the solid content particles that hold the oil content, it is possible to obtain not only the lubricity due to the presence of the solid content particles but also the lubricity due to the oil content held in the solid content particles of the grease. By not. For example, when the depth z is 1 μm, the life improvement effect of the fixing device F cannot be confirmed.

  Therefore, in order to prevent the heat conduction to the toner image t on the recording material P from being lowered and to suppress the slip and stick slip of the fixing film 30, the depth z of the plurality of recesses 30a2 is 2 to 2. 12 μm is preferable. In the present embodiment, the depth z of the plurality of recesses 30a2 is 6 μm.

Next, the volume (per unit area) of the plurality of recesses 30a2 on the inner surface of the base layer 30a will be described below. Regarding the contact thermal resistance between the surface of the glass coat layer 32c and the inner surface of the base layer 30a, the relationship with the depth z of the plurality of recesses 30a2 has been described above, but more strictly, the contact thermal resistance also affects the area ratio of the plurality of recesses 30a2. The contact thermal resistance increases as the area ratio increases. That is, the contact thermal resistance increases as the volume (per unit area) of the plurality of recesses 30a2 increases. Therefore, the volume of the plurality of recesses 30a2 per 1 cm ^{2 of the} inner surface of the base layer 30a needs to be at least 0.6 mm ³ or less from the viewpoint of contact thermal resistance.

Further, the relationship between the retention amount of grease and the abundance ratio of the convex flat portion 30a1 has been described above, but more strictly, the retention amount of grease also depends on the depth z of the plurality of recess portions 30a2, and as the depth increases. The holding amount increases. That is, the smaller the volume (per unit area) of the plurality of recesses 30a2, the smaller the amount of grease retained. Therefore, the volume of the plurality of recesses 30a2 per 1 cm ^{2 of the} inner surface of the base layer 30a is required to be at least 0.07 mm ³ or more from the viewpoint of the amount of grease retained.

Therefore, from the viewpoint of contact thermal resistance and the amount of retained grease, the volume of the plurality of recesses 30a2 per 1 cm ^{2 of the} inner surface of the base layer 30a is preferably 0.07 to 0.6 mm ³ . In the present embodiment, the volume of the plurality of recesses 30a2 per 1 cm ^{2 of the} inner surface of the base layer 30a is 0.24 mm ³ .

  For the measurement of the depth z and the volume of the plurality of recesses 30a2, a laser microscope [manufactured by Olympus Corporation: LEXT OLS4000] was used. The measuring method of the depth z is as follows. The average depth from the upper surface 30a12 of the projecting portion 30a11 of the convex flat portion 30a1 to the bottom surface 30a21 of the concave portion 30a2 is measured under the condition of a cutoff value λc = 0.25 mm by a method according to z = JIS B0601: 2001. The average height Wc of the undulating curve element.

  As a method for producing the fixing film 30 of this embodiment, a method is used in which a polyimide precursor liquid is cast on a cylindrical mold surface, and then imide is converted by heating to form a polyimide resin. The mold can be made of metal, glass, plastic with high heat resistance, or the like.

  As a method for obtaining the shape of the fixing film 30 on the inner surface side of the base layer 30a (the shape having the convex flat portion 30a1 and the plurality of concave portions 30a2), the outer surface of the mold to be used is previously formed on the inner surface of the base layer 30a of the fixing film 30. A method is used in which the shape is processed into an inverted shape. As a method of processing the outer surface of the mold into a predetermined shape of the inner surface of the base layer 30a, there are a method of cutting the mold surface and a method of etching the mold surface. In this embodiment, the die surface is cut to obtain a die having a shape obtained by inverting the inner surface shape of the base layer 30a of the fixing film 30, and the inner surface of the predetermined base layer 30a using the die. A fixing film 30 having a shape was obtained.

(4) Action / Effect of Fixing Film 30 First, description will be given of scraping due to rubbing at the fixing nip N of the fixing film 30 and the heater holder 32. FIG.

  5A, the inner surface of the base layer 130a of the roughened fixing film 130 as a conventional example in the fixing device at the start of use (new article) is in contact with the surface of the downstream jaw portion 131b of the heater holder 131 in the fixing nip portion N. The schematic diagram of the state which is rubbing is shown.

  As shown in FIG. 5A, the inner surface of the base layer 130a of the fixing film 130 has fine irregularities, and the fixing film 130 rotates in the direction of the arrow as the pressure roller (not shown) of the fixing device rotates. Yes. Further, there are fine irregularities on the surface of the downstream jaw portion 131 b of the heater holder 131. Here, since the contact area is low due to the contact between the fine irregularities, the contact surface pressure increases, and the stress on the contact surfaces of both increases. Further, when the unevenness on the inner surface of the base layer 130a and the unevenness on the surface of the downstream jaw portion 131b rub against each other, a force for bringing the inner surface of the base layer 130a and the surface of the downstream jaw portion 131b into close contact with each other at the fixing nip portion N. For this reason, rubbing and rubbing occurs while the unevenness of each other is engaged, and a high stress is applied to the engaged portion. As a result, the surface of the downstream jaw 131b and the inner surface of the base layer 130a are shaved.

  Since both the material of the heater holder 131 and the base layer 130a of the fixing film 130 are high heat-resistant resins, they are cut away from each other to some extent. However, since the heater holder 131 is substantially stationary with respect to the rotating fixing film 130, only the surface of the downstream jaw portion 131b is scraped. On the other hand, since the fixing film 130 is rotating, the entire circumference of the inner surface of the base layer 130a is scraped. Therefore, the fixing film 130 has a larger amount of scraping powder.

  In FIG. 5B, the inner surface of the base layer 130 a of the roughened fixing film 130 as a conventional example in the fixing device that has been used continues to rub against the surface of the downstream jaw portion 131 b of the heater holder 131 at the fixing nip portion N. A schematic diagram of the state is shown.

  As shown in FIG. 5B, the inner surface of the base layer 130a of the fixing film 130 and the surface of the downstream jaw 131b of the heater holder 131 are scraped as described above with the use of the fixing device. The fine irregularities on the surface of the part are gradually rounded. Since the heater holder 131 is substantially stationary with respect to the rotating fixing film 130, only the surface of the downstream jaw portion 131b is scraped. Therefore, the unevenness is rounded little by little as soon as the inner surface of the base layer 130a of the fixing film 130. However, due to the remaining unevenness, the contact area between the two remains low, and the frictional surfaces are rubbed with each other being engaged. Therefore, even if the unevenness is slightly rounded, it is difficult to reduce the generation amount of the shaving powder.

  And if it cuts more than a certain amount, not only the generation of scraping powder, but also the particulate material added to the heater holder 131 and the base layer 130a of the fixing film 130 falls off, which becomes an abrasive, and further scrapes. It will trigger. As a result, with the use of the fixing device, shaving powder is generated at an accelerated rate. For example, as the particulate material of the heater holder 131, there is a glass fiber added to the heater holder 131 for strength reinforcement. Examples of the particulate material of the base layer 130a of the fixing film 130 include a carbon-based additive for reinforcing the base layer 130a.

  6A, the inner surface of the base layer 30a of the fixing film 30 of this embodiment in the fixing device at the start of use (new article) is rubbed against the surface of the downstream jaw portion 31b of the heater holder 31 in the fixing nip portion N. A schematic diagram of the state is shown.

  As shown in FIG. 6A, the inner surface of the base layer 30a of the fixing film 30 has a convex flat portion 13a1 and a plurality of concave portions 30a2, and the tips of the plurality of protruding portions 13a11 constituting the convex flat portion 13a1. Is a smooth surface 13a12. The fixing film 30 rotates in the direction of the arrow as the pressure roller (not shown) 33 rotates. The surface of the downstream jaw 31b of the heater holder 31 has fine irregularities. Here, on the inner surface of the base layer 30a of the fixing film 30, the smooth surface 13a12 of the convex flat portion 13a1 comes into contact with the surface of the downstream jaw portion 31b. Therefore, when the unevenness on the surface of the downstream jaw portion 31b and the inner surface of the base layer 30a are rubbed, the unevenness of each other is hardly engaged, and high stress due to the engagement of the unevenness is hardly applied. Therefore, compared with the conventional roughened fixing film 130, generation of scraping powder in the fixing device at the start of use (new article) can be suppressed.

  FIG. 6B is a schematic view showing a state in which the inner surface of the base layer 30a of the fixing film 30 of this embodiment is in sliding contact with the surface of the downstream jaw portion 31b of the heater holder 31 at the fixing nip portion N in the fixing device that has been used. The figure is shown.

  As shown in FIG. 6B, the surface of the downstream jaw 31b is scraped as described above with the use of the fixing device, so that the fine irregularities on the surface of the downstream jaw 31b are gradually rounded. . In particular, since the heater holder 131 is substantially stationary with respect to the rotating fixing film 30, only the surface of the downstream jaw portion 31b is scraped. Therefore, the unevenness is rounded little by little as soon as the inner surface of the base layer 30a of the fixing film 30. Then, since the smooth surfaces 13a12 of the plurality of projecting portions 13a11 constituting the convex flat portion 13a1 of the inner surface of the base layer 30a of the fixing film 30 come into contact with the surface of the downstream jaw portion 31b, the contact area between the two is greatly increased. To increase. Further, since the unevenness between the inner surface of the base layer 30a and the surface of the downstream jaw portion 31b is hardly engaged with each other, high stress due to the engagement of the unevenness is hardly applied. Therefore, the generation of abrasion powder on the inner surface of the base layer 30a of the fixing film 30 in the fixing device when the use is continued can be greatly suppressed.

  Next, scraping due to rubbing at the fixing nip N of the fixing film 30 and the heater 32 will be described. In the rubbing between the fixing film 30 and the fixing nip N of the heater 32, the rubbing surface of the heater 32 with the inner surface of the base layer 30a of the fixing film 30 is covered with the glass coat layer 32c. The inner surface of 30a is unilaterally shaved.

  7A, the inner surface of the base layer 130a of the roughened fixing film 130 as a conventional example in the fixing device at the start of use (new article) is in contact with the surface of the glass coat layer 132c of the heater 132 in the fixing nip N. The schematic diagram of the state which is rubbing is shown.

  As shown in FIG. 7A, the inner surface of the base layer 130a of the fixing film 130 has fine irregularities, and the fixing film 130 rotates in the direction of the arrow as the pressure roller (not shown) of the fixing device rotates. Yes. The surface of the glass coat layer 132c of the heater 132 is slightly uneven. Here, since the contact area is low due to the contact between the fine irregularities, the contact surface pressure increases, and the stress on the contact surfaces of both increases. Further, when the irregularities on the surface of the glass coat layer 132c and the irregularities on the inner surface of the base layer 130a are rubbed together, a force for bringing the surface of the glass coat layer 132c and the inner surface of the base layer 130a into close contact at the fixing nip portion N. For this reason, rubbing and rubbing occurs while the unevenness of each other is engaged, and a high stress is applied to the engaged portion. As a result, the inner surface of the base layer 130a of the fixing film 130 is scraped off.

  In FIG. 7B, the inner surface of the base layer 130 a of the roughened fixing film 130 as a conventional example in the fixing device that has been used continues to rub against the surface of the glass coat layer 132 c of the heater 132 in the fixing nip N. A schematic diagram of the state is shown.

  As shown in FIG. 7 (b), the inner surface of the base layer 130a of the fixing film 130 is scraped as described above with the use of the fixing device, so that there is a slight unevenness between the inner surface of the base layer 130a and the surface of the glass coat layer 132c. It will be rounded one by one. However, due to the remaining unevenness, the contact area between the two remains low, and the frictional surfaces are rubbed with each other being engaged. Therefore, even if the unevenness on the inner surface of the base layer 130a of the fixing film 130 is slightly rounded, the amount of scraped powder is hardly reduced.

  And if it cuts more than a certain amount, not only the generation of scraping powder but also the particulate material added to the base layer 130a of the fixing film 130 falls off, and they become an abrasive, inducing further scraping. End up. As a result, with the use of the fixing device, shaving powder is generated at an accelerated rate. For example, the particulate material of the base layer 130a of the fixing film 130 includes a carbon-based additive for reinforcing the base layer 130a.

  8A, the inner surface of the base layer 30a of the fixing film 30 of this embodiment in the fixing device at the start of use (new article) rubs against the surface of the glass coat layer 32c of the heater 32 at the fixing nip N. A schematic diagram of the state is shown.

  As shown in FIG. 8A, the inner surface of the base layer 30a of the fixing film 30 has a convex flat portion 13a1 and a plurality of concave portions 30a2, and the tips of the plurality of protruding portions 13a11 constituting the convex flat portion 13a1. Is a smooth surface 13a12. The fixing film 30 rotates in the direction of the arrow as the pressure roller (not shown) 33 rotates. The surface of the glass coat layer 132c of the heater 32 has slightly fine irregularities. Here, on the inner surface of the base layer 30a of the fixing film 30, the smooth surface 13a12 of the convex flat portion 13a1 comes into contact with the surface of the glass coat layer 132c. Therefore, when the irregularities on the surface of the glass coat layer 132c and the inner surface of the base layer 30a rub against each other, the irregularities are hardly engaged with each other, and high stress due to the irregularities is hardly applied. Therefore, the generation of shaving powder in the fixing device at the start of use (new article) can be suppressed as compared with the fixing film 130 having the roughened inner surface of the base layer 130a as a conventional example.

  FIG. 8B is a schematic view showing a state in which the inner surface of the base layer 30a of the fixing film 30 of this embodiment is rubbed against the surface of the glass coat layer 32c of the heater 32 in the fixing nip N in the fixing device that has been used. The figure is shown.

  As shown in FIG. 8 (b), when the irregularities on the surface of the glass coat layer 132c and the inner surface of the base layer 30a rub against each other, the irregularities are hardly engaged with each other. The stress due to can be reduced. Therefore, the generation of scraping powder on the inner surface of the base layer 30a of the fixing film 30 in the fixing device when the use is continued can be greatly suppressed.

  Due to the mechanism described above, the scraping of the fixing film 30 with the heater holder 31 and the heater 32 by the rubbing at the fixing nip portion N is less than that of the fixing film 130 having a roughened inner surface of the conventional example. By using the fixing film 30 shown in FIG.

  Next, the effect of suppressing the slip and stick slip of the fixing film 30 when the fixing device F is continuously used by suppressing the shaving powder will be described.

  First, the slip and stick slip of the fixing film 30 will be described.

  The slip of the fixing film 30 occurs when the sliding resistance at the fixing nip portion N between the inner surface of the base layer 30a of the fixing film 30 and the surface of the downstream jaw portion 31b of the heater holder and the surface of the glass coat layer 32c of the heater increases.

  The rotation driving of the fixing film 30 is performed by the driven rotation by the frictional force between the release layer 33 c on the surface of the pressure roller 33 generated by the driving of the pressure roller 33 and the release layer 30 c on the surface of the fixing film 30. .

  When the recording material P passes through the fixing nip N (when the toner image t is fixed), the release layer 33 c on the surface of the pressure roller 33 generated by the rotation of the pressure roller 33 and the toner image of the recording material P The recording material P is conveyed by the frictional force with the surface (surface) opposite to the carrying surface. Further, the fixing film 30 is driven to rotate by the frictional force between the toner image carrying surface (front surface) of the recording material P and the release layer 33 c on the surface of the fixing film 30.

  Here, since the recording material P has various media and carries the toner image t according to the recorded image, the release of the toner image carrying surface (surface) of the recording material P and the surface of the fixing film 30 is performed. The frictional force with the layer 30c varies depending on the situation. When this frictional force is small, the sliding resistance at the fixing nip portion N between the inner surface of the base layer 30a of the fixing film and the surface of the downstream jaw portion 31b of the heater holder and the surface of the glass coat layer 32c of the heater overcomes the fixing film 30. Cannot be driven to rotate.

  If slip occurs in the fixing film 30 when the recording material P is passed, the recording material P is conveyed by the rotation of the pressure roller 33 while the fixing film 30 is stopped. As a result, the portion of the recording material P in contact with the surface of the fixing film 30 is excessively heated, and a hot offset occurs where the toner image t is separated from the surface of the fixing film 30. Further, a part of the toner image t may be scraped off on the surface of the fixing film 30 that has stopped, and the image quality is greatly deteriorated. Further, the sliding resistance at the fixing nip portion N of the fixing film 30 is increased, so that the release layer 33c on the surface of the pressure roller 33 and the surface (back surface) of the recording material P opposite to the toner image carrying surface. If the frictional force is exceeded, the recording material P cannot be transported and a jam occurs.

  The stick slip of the fixing film 30 also occurs when the sliding resistance at the fixing nip portion N of the fixing film 30 increases, and particularly when the fixing device is operated at a low speed and a high temperature.

  When the sliding resistance at the fixing nip portion N of the fixing film 30 increases, the phenomenon that the above-described slip of the fixing film 30 occurs for a moment may be repeated. This phenomenon is called stick-slip. As described above, chattering noise may be generated due to the fixing film 30 periodically stopping and sliding. Especially for color printers that require high gloss on the toner image surface after fixing, heat fixing under high pressure and high gloss on glossy paper can be achieved at low speed and high temperature. Since there is a mode using a fixing operation, stick slip is likely to occur.

  As described above, the slip and stick slip of the fixing film 30 occur when the sliding resistance at the fixing nip portion N of the fixing film 30 increases. The sliding resistance of the fixing film 30 at the fixing nip portion N is increased when scraping powder is generated. The sliding resistance at the fixing nip N of the fixing film 30 when scraping powder is generated will be described below.

  In the fixing nip N, grease as a lubricant is interposed between the inner surface of the fixing film base layer 30a, the surface of the downstream jaw 31b of the heater holder, and the surface of the glass coat layer 32c of the heater, thereby fixing the fixing nip of the fixing film. The sliding resistance is reduced. As the fixing device is used, the grease deteriorates in viscosity, and the solid lubricant and the fluorine oil held in the solid lubricant are separated by heating for a long time. The separated fluorine oil easily moves to a place other than the sliding portion between the inner surface of the base layer 30a, the surface of the glass coat layer 32c, and the surface of the downstream jaw portion 31b due to capillary action, resulting in a situation where the oil film runs out. Go.

  In this way, the sliding resistance of the fixing film 30 at the fixing nip portion gradually increases as the fixing device is used. When the sliding resistance at the fixing nip portion of the fixing film 30 becomes larger than a predetermined value, the frequency of occurrence of slips and stick slips of the fixing film 30 increases, so that the fixing device reaches the end of its life before that.

  However, when shavings are generated, the life of the fixing device is reduced. Since the shaving powder is generated and exists at the sliding portion, the grease existing area is replaced. That is, with the generation of shaving powder in the sliding portion, the grease is driven out to a place other than the sliding portion. Furthermore, as the fixing film 30 rotates, the edge portion in the short direction of the glass coat layer 32 c of the heater 32 and the upstream side in the recording material conveyance direction of the heater holder 32 immediately before the fixing film 30 enters the fixing nip N. Occasionally grease is scraped off at the part. Furthermore, the fixing film 30 may accumulate in a portion on the heater holder 32 where the distance between the fixing film 30 and the heater holder 32 immediately after coming out of the fixing nip N is small.

  As a result, the shaving powder moves with the grease, for example, to the above location while holding the grease, and as a result, the grease is depleted as compared with the case where the shaving powder is not generated (sufficiently less). That is, the life of the fixing device is reduced.

  Next, the streaky uneven gloss image will be described.

  When the shaving powder is generated, the solid components of the shaving powder and the grease are easily fixed on the surface of the glass coat layer 32c of the heater 32. Then, the contact thermal resistance between the glass coat layer 32c and the inner surface of the base layer 30a of the fixing film 30 greatly increases at the portion where the fixed matter is generated. Further, in the fixed matter generating portion, the pressure surface pressure between the glass coat layer 32c and the inner surface of the base layer 30a is locally high, and as a result, the temperature and pressure received by the toner image t on the recording material P are fixed. The film 30 becomes non-uniform in a local portion in the longitudinal direction. As a result, in the recorded image, uneven glossiness appears in the recording material conveyance direction, and the image quality is impaired.

  Furthermore, when the fixed matter becomes large, the inner surface of the base layer 30a of the fixing film 30 may be locally scraped, and further, uneven fixing may be promoted to lower the image quality.

  The above adverse effects are all caused by the generation of shaving powder. That is, the above-described adverse effects can be suppressed by suppressing the generation of shaving powder.

(5) Results of Image Output Experiment Next, results of an image output experiment in which printing is performed using a color printer equipped with the fixing device F of this embodiment will be described.

  As for printing durability, CS-814 (Canon sales, product name) is used as a recording material, and an image with a printing rate of 4% for each color of Y (yellow), M (magenta), C (cyan), and BK (black) is used. 200,000 sheets were printed using During endurance, image sampling and occurrence of stick-slip noise were checked at the start of endurance and every 50,000 sheets thereafter.

  A plain paper mode is used as the print mode. In the color printer used in the experiment, the process speed at this time is 150 mm / sec, and the throughput is 25 sheets per minute.

  As a sampling image, HP Premien Presentation 120 gsm (Hewlett Packard, product name) was used as a recording material, and Y, M, C, BK, R, B, and G solid images and halftone images were output, respectively. The glossy paper mode was used as the sampling image printing mode. In the image forming apparatus used in the experiment, the process speed at this time is 30 mm / sec, and the throughput is 5 sheets per minute.

  Image evaluation was performed from sampled images, and ranking evaluation was performed in terms of vertical streaky gloss unevenness, image defects due to fixing slip, and image defects on the end side of the recording material due to damage at the end of the fixing film 30 in the longitudinal direction. . Regarding stick-slip, ranking evaluation was performed for the magnitude and frequency of stick-slip sound during sampling image printing. As the rank, the evaluation was performed by setting the case where the image was bad or no stick-slip sound was generated at all, and the case where it was generated as x.

  The atmosphere environment in which the experiment was performed is a temperature of 23 ° C. and a humidity of 50%.

  The evaluation results are shown in Table 1. As shown in Table 1, image defects and stick-slip noise did not occur until the evaluation of 200,000 sheets was completed.

  Next, the result of an image output experiment in which printing is performed using a color printer equipped with a conventional fixing device will be described as a comparative example.

  The configuration of the color printer of the comparative example is the same as that of the color printer equipped with the fixing device F of this embodiment. The basic configuration of the fixing device of the comparative example is the same as that of the fixing device F of the present embodiment, but only the fixing film is used under different conditions (Comparative Examples 1 to 10).

  As Comparative Example 1, a fixing film having a roughened inner surface of the base layer was used. As Comparative Example 2, a fixing film having only a smooth surface on the inner surface of the base layer was used. As Comparative Example 3, a fixing film having a planar portion composition ratio of 85% on the inner surface of the base layer and having the same structure as that of Example 1 was used for other conditions. As Comparative Example 4, a fixing film having a plane part composition ratio of 30% on the inner surface of the base layer and having the same structure as that of Example 1 was used for other conditions. As Comparative Example 5, a fixing film having a recess depth of 15 μm on the inner surface of the base layer and having the same configuration as in Example 1 was used for other conditions.

As Comparative Example 6, a fixing film having a recess depth of 1 μm on the inner surface of the base layer and having the same configuration as in Example 1 was used for other conditions. As Comparative Example 7, a fixing film having a recess volume per 1 cm ² of the base layer inner surface of 0.05 mm ³ and having the same configuration as that of Example 1 was used for the other conditions. As Comparative Example 8, a fixing film having a recess volume per 1 cm ² of the base layer inner surface of 0.70 mm ³ and having the same configuration as in Example 1 was used for other conditions.

  As Comparative Example 9, the surface roughness of the inner surface of the base layer is measured by a method according to JIS B0601: 2001 under the condition of a cut-off value λc = 0.8 mm, and the fixing film has a protrusion peak height Rpk of 3 μm. Was used. With respect to other conditions, the fixing film has the same configuration as in Example 1. As Comparative Example 10, the surface roughness of the inner surface of the base layer was measured using a fixing film having a maximum peak height Rzjis of 5 μm measured by a method according to JIS B0601: 2001 under the condition of a cutoff value λc = 0.1 mm. Using. With respect to other conditions, the fixing film has the same configuration as in Example 1.

  The evaluation results are shown in Table 2. In Comparative Example 1, stick slip and vertical stripe-like gloss unevenness occurred on 150k sheets, and fixing slip occurred on 200k sheets. In Comparative Example 2, stick slip occurred at 100k sheets, and fixing slip occurred at 150k sheets. In Comparative Example 3, stick slip and vertical stripe-like gloss unevenness occurred on 150k sheets, and fixing slip occurred on 200k sheets. In Comparative Example 4, an image defect due to damage occurred at the edge of the fixing film in 200k sheets. In Comparative Example 5, the gloss level remained greatly reduced from the initial 200 k sheets.

  In Comparative Example 6, stick slip occurred at 100k sheets, and fixing slip occurred at 150k sheets. In Comparative Example 7, stick slip occurred at 150k sheets, and fixing slip occurred at 200k sheets. In Comparative Example 8, the gloss level remained greatly reduced from the initial 200 k sheets.

  In Comparative Example 9, fixing slip, stick slip, and vertical stripe-like gloss unevenness occurred on 200k sheets. In Comparative Example 10, fixing slip, stick slip, and vertical stripe-like gloss unevenness occurred on 200k sheets.

  The reason why the life of the fixing device of this embodiment can be effectively extended compared to Comparative Examples 1 and 2 is due to the action and effect of the fixing film 30 described in (4). Regarding the differences in fixing slip, stick slip, vertical stripe-like gloss unevenness, fixing film edge damage, and glossiness in Comparative Examples 3 to 10, explanations regarding each parameter in the fixing film 30 of the present embodiment described in (3) are given. It is as follows.

(6) Summary As described above, according to the fixing film 30 of this embodiment, the heater holder 31 and the inner surface of the fixing film 30 can be prevented from being scraped. As a result, it is possible to suppress the slip and stick slip of the fixing film 30 and extend the life of the fixing device more effectively, and further suppress the occurrence of uneven gloss and obtain a high-quality recorded image. be able to.

[Example 2]
Another example of the fixing film 30 will be described. The fixing film 30 shown in this example has the same configuration as the inner surface of the base layer of the fixing film of Example 1 (the ratio of the convex flat surface area, the surface roughness of the inner surface of the base layer, the depth of the recess, the recesses per 1 cm ^{2 of the} inner surface of the base layer inner film. The volume is the same), but the shape of the protrusion and the recess is different.

  9, FIG. 10, FIG. 11, FIG. 12, and FIG. 13 are enlarged schematic views of a part of the inner surface of the base layer 30a of the fixing film 30 of this embodiment from the heater 32 side.

  The fixing film 30 shown in FIG. 9 is provided with a plurality of square recesses 30a2 that are independent of four sides in the longitudinal direction and the short direction of the fixing film 30 on a smooth flat portion 30a1. The plurality of independent square recesses 30 a 2 are arranged in a staggered pattern along the longitudinal direction of the fixing film 30. Hereinafter, the fixing film 30 having the inner surface of the base layer 30a shown in FIG. 9 is referred to as Example 2-1.

  The fixing film 30 shown in FIG. 10 is provided with a plurality of square concave portions 30a2 independently on the smooth flat surface portion 30a1 so that the diagonal direction is the same as the longitudinal direction of the fixing film 30. The plurality of independent square recesses 30 a 2 are arranged so as to be slightly shifted in a direction obliquely intersecting with the longitudinal direction of the fixing film 30. Hereinafter, the fixing film 30 having the inner surface of the base layer 30a shown in FIG. 10 is referred to as Example 2-2.

  In the fixing film 30 of Example 2-1 and Example 2-2, the size of the square recess 30a2 is about 310 μm on one side.

  The fixing film 30 shown in FIG. 11 has an inner surface of the base layer 30a having a shape obtained by inverting the convex flat portion 30a1 and the concave portion 30a2 of the inner surface of the base layer 30a of the fixing film 30 of the first embodiment. That is, the shape of the protrusion 30a11 constituting the convex flat portion 30a1 on the inner surface of the base layer 30a is an indeterminate ellipse, and the average outer diameter of the protrusion 30a11 is about 650 μm. Hereinafter, the fixing film 30 having the inner surface of the base layer 30a shown in FIG. 10 is referred to as Example 2-3.

  A fixing film 30 shown in FIG. 12 is formed by forming convex flat portions 30 a 1 and concave portions 30 a 2 on the inner surface of a base layer 30 a into a plurality of oblique lines that obliquely intersect the longitudinal direction of the fixing film 30. Hereinafter, the fixing film 30 having the inner surface of the base layer 30a shown in FIG. 12 is referred to as Example 2-4.

  The fixing film 30 shown in FIG. 13 has a concave portion 30a2 having a complicated shape such that a meandering protrusion 30a11 and a substantially rhombic protrusion 30a12 are provided on a smooth flat surface 30a1 along the longitudinal direction of the fixing film 30. Is formed. Hereinafter, the fixing film 30 having the inner surface of the base layer 30a shown in FIG. 13 is referred to as Example 2-5.

  For the fixing films 30 of Examples 2-1, 2-2, 2-3, 2-4, and 2-5, an image output experiment equivalent to (5) of Example 1 was performed. As a result, image defects and stick slip did not occur until the evaluation of 200,000 sheets was completed.

  Since the operational effects of the fixing film 30 of the present embodiment are the same as those of the first embodiment in principle, the description thereof is omitted here. However, with regard to the shape of the recess 30a2, the strength of the fixing film 30 is stronger when the recess 30a2 is interrupted (independent) in all directions on the inner surface of the base layer 30a of the fixing film 30. A tensile strength test was performed as a fixing film strength measurement. If the concave portion 30a2 is connected without interruption in a certain direction of the inner surface of the base layer 30a of the fixing film 30, the strength may be slightly lowered and the portion may be broken starting from the portion where the concave portion is connected at the time of breaking. confirmed.

  For example, when compared with Examples 2-1, 2-2, 2-3, 2-4, and 2-5, Example 2-4 had a slightly lower breaking strength in the tensile test than other examples. . However, if the strength of the inner surface of the base layer 30a of the fixing film 30 is sufficiently secured, the fixing film 30 as in Example 2-4 can also be used. Actually, the durability problem due to strength was not confirmed in the fixing film 30 of Example 2-4 as in this evaluation test.

  As described above, also in the fixing film 30 of the present embodiment, the same operational effects as those of the fixing film 30 of the first embodiment can be obtained.

[Other embodiments]
The shape of the inner surface of the base layer 30a of the fixing film 30 is not limited to the shape shown in the first and second embodiments. Any shape may be used as long as the grease is held and a stable contact surface with the heater 32 and the heater holder 31 is obtained.

  The same effect can be obtained in an electromagnetic induction heating type fixing device in which a fixing film capable of electromagnetic induction is used as the fixing film and a ceramic sliding plate is brought into contact with the inner surface of the fixing film instead of the heater. A similar effect can be obtained also in a fixing device of a type that uses a heating roller in place of the pressure roller and presses the film assembly unit to the heating roller.

  In the first and second embodiments, the suppression of scraping caused by the rubbing friction between the rotating fixing film 30 and the substantially stationary heater holder 31 and heater 32 has been described. However, the member rubbing against the inner surface of the fixing film 30 does not necessarily need to be stationary. Even when the member is rubbed by rotating or moving with a speed difference from the inner surface of the fixing film 30, the same effect can be obtained as long as the grease is retained and a stable contact surface is obtained. Can be applied.

  The fixing device F including the fixing film 30 of the first and second embodiments is not limited to use as a device that heat-fixes an unfixed toner image on a recording material. For example, it can also be used as an image heating apparatus that heats an unfixed toner image to be applied to a recording material, or an image heating apparatus that heats a toner image heated and fixed on a recording material to give glossiness to the surface of the toner image.

30: Fixing film, 30a: Base layer, 30a1: Smooth flat part, 30a2: Concave part, 31: Heater holder, 32: Heater, 33: Pressure roller, F: Fixing device, N: Fixing nip part, P: Recording material, t: Unfixed toner image

Claims (14)

A flexible member that is in contact with the recording material carrying the image and moves together with the recording material. The heating member and a base layer that is in contact with the supporting member that supports the heating member are provided on the opposite side of the recording material. In flexible members,
A surface of the base layer that comes into contact with the heating body and the support member has a smooth flat surface portion and a plurality of independent concave portions formed in the smooth flat surface portion.   2. The flexible member according to claim 1, wherein a ratio of the smooth flat portion to the surface having the smooth flat portion and the plurality of concave portions is 40 to 80%.   2. The flexible member according to claim 1, wherein an average depth of the plurality of concave portions of the surface having the smooth flat portion and the plurality of concave portions is 2 to 12 μm.   The average depth of the plurality of recesses is an average height Wc of a waviness curve element measured by a method according to JIS B0601: 2001 under the condition of a cutoff value λc = 0.25 mm. The flexible member according to claim 3. ^2. The volume of the plurality of recesses per 1 cm ^{2 of the} surface having the smooth flat portion and the plurality of recesses is 0.07 to 0.6 mm ³ . Flexible member.   The surface roughness of the surface having the smooth flat portion and the plurality of concave portions is measured under the condition of a cutoff value λc = 0.8 mm by a method according to JIS B0601: 2001. The flexible member according to claim 1, wherein the part mountain height Rpk is 2 μm or less.   The surface roughness of the surface having the smooth flat portion and the plurality of concave portions is measured under the condition of a cutoff value λc = 0.1 mm by a method according to JIS B0601: 2001. The flexible member according to claim 1, wherein a peak height Rzjis is 3.5 μm or less. A heating member, a support member that supports the heating member, and a flexible member that moves in contact with the recording material in contact with the recording material carrying an image, and the heating member and the side opposite to the side in contact with the recording material A flexible member having a base layer in contact with the support member; and a backup member that sandwiches the flexible member together with the heating body and the support member to form a nip portion, and the recording material at the nip portion. In an image heating apparatus that heats an image while sandwiching and conveying the image,
An image heating apparatus, wherein a surface of the base layer that contacts the heating body and the support member includes a smooth flat surface portion and a plurality of independent concave portions formed in the smooth flat surface portion.   The image heating apparatus according to claim 8, wherein a ratio of the smooth flat portion of the surface having the smooth flat portion and the plurality of concave portions is 40% to 80%.   The image heating apparatus according to claim 8, wherein an average depth of the plurality of concave portions of the surface having the smooth flat portion and the plurality of concave portions is 2 to 12 μm.   The average depth of the plurality of recesses is an average height Wc of a waviness curve element measured by a method according to JIS B0601: 2001 under the condition of a cutoff value λc = 0.25 mm. The image heating apparatus according to claim 10. 9. The volume of the plurality of recesses per 1 cm ^{2 of the} surface having the smooth flat portion and the plurality of recesses is 0.07 to 0.6 mm ³ . Image heating device.   The surface roughness of the surface having the smooth flat portion and the plurality of concave portions is measured under the condition of a cutoff value λc = 0.8 mm by a method according to JIS B0601: 2001. The image heating apparatus according to claim 8, wherein the part mountain height Rpk is 2 μm or less.   The surface roughness of the surface having the smooth flat portion and the plurality of concave portions is measured under the condition of a cutoff value λc = 0.1 mm by a method according to JIS B0601: 2001. The image heating apparatus according to claim 8, wherein the peak height Rzjis is 3.5 μm or less.