JP6563061B2 - Fixing device - Google Patents

Description

The present invention is an electrophotographic copying machine, relates to a fixing apparatus mounted on an image forming apparatus such as an electrophotographic printer (fixing device).

  As a fixing device mounted on an electrophotographic copying machine or printer, a film heating type is known. This film heating type fixing device includes a heater having a heating resistor on a ceramic substrate, a cylindrical film that moves while in contact with the heater, and a pressure roller that forms a nip portion with the heater sandwiched between the films. Etc. 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 on 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 waiting for a print command is small.

  By the way, as a constituent material of toner for electrophotography in recent years, it is said that many include release wax. This is for the purpose of imparting effects such as adjusting the glossiness of the printed image and the dispersibility of the pigment, and is added to prevent fixing offset. There are several types of fixing offset phenomena as shown below.

  In the process of fixing to the recording material, if the film is not sufficiently heated (low temperature), the toner does not melt sufficiently and the fixing force to the recording material is reduced, so that a part of the toner adheres to the surface of the fixing film. Resulting in. This phenomenon is called cold offset, and the portion where the toner adheres to the film surface appears as an image defect on the recording material. Further, since the fixing toner has a weak fixing force, it may be peeled off from the recording material by friction or the like.

  On the contrary, when the film temperature is too high, the toner is sufficiently melted, but the viscosity is lowered, and a part of the melted toner is peeled off from the recording material to contaminate the film surface. This phenomenon is called hot offset and results in image loss on the recording material, similar to cold offset.

  Therefore, Patent Document 1 proposes to add a wax component to the toner as a release agent when preventing fixing offset. By encapsulating the release wax in the toner, the release wax moves to the interface between the molten toner and the fixing member at the time of heat-fixing, and the anti-offset performance is improved. Further, Patent Document 2 proposes a technique of adding two or more types of release waxes to the toner in order to improve the anti-offset performance.

JP-A-8-184992 JP 2000-3070 A

  By the way, the pressure roller has a cored bar, an elastic layer formed on the cored bar, and a release layer formed on the elastic layer, and is elastic so as not to protrude from the end face of the film. The length of the layer and the release layer is shorter than the total length of the film. Therefore, a gap corresponding to the thickness of the elastic layer and the release layer is formed between the core metal and the film protruding outward from the elastic layer and the release layer of the pressure roller.

  Further, the release wax contained in the toner image is liquefied by the recording material being nipped and conveyed by the film and the pressure roller at the nip portion and being pressurized simultaneously with the heating. Most of the release wax adheres after being transferred to the recording material together with the molten toner image, but a part of the release wax is vaporized to be in a gaseous state. The vaporized release wax component floats in the fixing unit as small-diameter particles having a liquid phase or solid phase diameter of 0.1 μm or less depending on the ambient temperature.

  However, due to the presence of the gap, an air flow is generated in the fixing device when the recording material is conveyed, and the action of pushing out the air in the fixing device together with the recording material to the outside of the printer becomes strong, and the small diameter particles are fixed to the fixing device. (Device) It may be discharged outside.

SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device that can reduce the number of small-sized particles vaporized from a release wax contained in a toner image to the outside of the fixing device .

In order to achieve the above object, a fixing device according to the present invention includes:
A cylindrical film that contacts an unfixed toner image formed on the recording material;
A cover that covers the outer peripheral surface of the film over the longitudinal direction of the film;
A fixing device for fixing an unfixed toner image on a recording material using heat from the film,
As the distance between the outer peripheral surface and the cover of the end of the film in the longitudinal direction is smaller than the distance between the outer peripheral surface and the cover of the central portion of the film in the longitudinal direction, the cover Is provided so as to be curved toward the both end portions from the central portion in the longitudinal direction .
The fixing device according to the present invention includes:
A cylindrical film that contacts an unfixed toner image formed on the recording material;
A pressure roller in contact with the outer peripheral surface of the film;
A support surface that supports an inner surface of an end portion of the film in the longitudinal direction of the film, and a restriction portion that faces the end surface of the film in the longitudinal direction, and restricts movement of the film in the longitudinal direction. A regulating member that is provided one by one at positions corresponding to both end portions of the film in the longitudinal direction;
A cover that covers the outer peripheral surface of the film over the longitudinal direction of the film;
A fixing device that fixes an unfixed toner image on a recording material using heat from the film at a nip portion between the film and the pressure roller,
A distance between an imaginary line connecting positions farthest from the nip portion of the support surfaces of the two regulating members and an end portion of the cover in the longitudinal direction is the imaginary line. The cover is provided so as to be curved toward the both ends from the center in the longitudinal direction so as to be smaller than the distance between the cover and the center of the cover in the longitudinal direction .
The fixing device according to the present invention includes:
A cylindrical film that contacts an unfixed toner image formed on the recording material;
A cover that covers the outer peripheral surface of the film over the longitudinal direction of the film;
A fixing device for fixing an unfixed toner image on a recording material using heat from the film,
The cover is curved so that a central portion in the longitudinal direction swells in a radial direction of the film rather than an end portion.

According to the present invention, it is possible to provide a fixing device capable of reducing the number of small-sized particles vaporized from the release wax contained in the toner image to the outside of the fixing device .

Cross section of image forming apparatus (A) is sectional drawing of the fixing device which concerns on Example 1, (b) is a front view of the fixing device which concerns on Example 1. FIG. FIG. 5A is a cross-sectional view of a fixing device film and a pressure roller in the longitudinal direction according to the comparative example, and a cross-sectional view in the vicinity of the longitudinal direction end, and FIG. (A) is a cross-sectional view of the fixing device according to the first embodiment, and a cross-sectional view of the pressure roller in the longitudinal direction and the vicinity of the longitudinal end, and (b) is a cross-sectional view of the fixing device according to the first embodiment. (A) is a cross-sectional view of the fixing device according to the second embodiment, and a cross-sectional view of a longitudinal end portion of the pressure roller and the vicinity of the longitudinal end portion, and (b) is a cross-sectional view of the fixing device according to the second embodiment. FIG. 6A is a cross-sectional view of the fixing device according to the third embodiment in the longitudinal direction of the film and the pressure roller and the vicinity of the longitudinal end, and FIG. 5B is a cross-sectional view of the fixing device according to the third embodiment. (A) is a cross-sectional view of the fixing device according to the fourth embodiment, and a cross-sectional view of the pressure roller in the longitudinal direction and the vicinity of the longitudinal end, and (b) is a cross-sectional view of the fixing device according to the fourth embodiment. (A) is a cross-sectional view of the fixing device according to the fifth embodiment in the longitudinal direction of the film and the pressure roller, and a cross-sectional view of the vicinity of the longitudinal end portion, and (b) is a cross-sectional view of the fixing device according to the fifth embodiment. (A) is a cross-sectional view of the fixing device according to the sixth embodiment in the longitudinal direction of the film and pressure roller and the vicinity of the longitudinal direction end, and (b) is a cross-sectional view of the fixing device according to the sixth embodiment. (A) is a cross-sectional view of the fixing device according to the seventh embodiment in the longitudinal direction of the film and pressure roller and the vicinity of the longitudinal direction end, and (b) is a cross-sectional view of the fixing device according to the seventh embodiment. FIG. 6A is a cross-sectional view of a fixing device according to an eighth embodiment, a longitudinal end portion of the pressure roller and the vicinity of the longitudinal end portion, and FIG. 5B is a cross-sectional view of the fixing device according to the eighth embodiment. (A) is a cross-sectional view of the fixing device according to the ninth embodiment, and a longitudinal section of the pressure roller and the vicinity of the longitudinal end thereof, and (b) is a sectional view of the fixing device according to the ninth embodiment. (A) is a cross-sectional view of the fixing device according to the tenth embodiment, a longitudinal end portion of the pressure roller and the vicinity of the longitudinal end portion, and (b) is a cross-sectional view of the fixing device according to the ninth embodiment. (A) is a cross-sectional view of the fixing device according to the eleventh embodiment, and a cross-sectional view of the pressure roller in the longitudinal direction and the vicinity of the end in the longitudinal direction. (A) is a longitudinal sectional view of the film, pressure roller, and second film of the fixing device according to the twelfth embodiment, and a cross-sectional view of the vicinity of the longitudinal end portion. Cross section FIG. 10A is a cross-sectional view of a fixing device according to Embodiment 13, and FIG. The figure which showed the structure of the heater of the fixing device which concerns on Example 13. FIG. Diagram showing the radial deflection of the film (A) is a cross-sectional view of the fixing device according to Example 13, (b) is a diagram showing the configuration in the longitudinal direction of the film, flange, and cover according to Example 13, and (c) is Comparative Example 3 and Comparative Example. 4 is a diagram showing the radial distance between the cover and the film in Example 13 and Example 13. Diagram showing the temperature of the recording material, film, and pressure roller during the fixing process (A) is a diagram showing the airflow between the film and the cover (when the distance between the film and the cover is long), (b) is a diagram showing the airflow between the film and the cover (between the film and the cover) When distance is short) (A) is a cross-sectional view of a fixing device according to a modification of the thirteenth embodiment, (b) is a diagram showing a configuration in the longitudinal direction of a film, a flange, and a cover according to the modification of the thirteenth embodiment. The figure which showed the distance of the radial direction of the cover and film in the comparative example 4 and the modification of Example 13

  Hereinafter, the present invention will be described in detail with reference to the drawings. Although the preferred embodiment of the present invention is an example of the best embodiment of the present invention, the present invention is not limited by the following examples, and various other configurations are possible within the scope of the idea of the present invention. It is possible to replace this with a known configuration.

[Example 1]
(1) Example of Image Forming Apparatus FIG. 1 is a cross-sectional view showing a schematic configuration of an image forming apparatus in which a fixing device according to the present invention can be mounted. This image forming apparatus is a full-color printer using an electrophotographic recording technique.

  An image forming unit that forms a toner image on the recording material P includes four image forming stations Pa, Pb, Pc, and Pd. Each image forming station includes a photoreceptor 117, a charging member 119, a laser scanner 118, a developing device 120, a transfer member 124, and a cleaner 122 for cleaning the photoreceptor. The image forming unit further includes a belt 123 that conveys the toner image while being carried, and a secondary transfer roller 121 that transfers the toner image from the belt to the recording material P. Since the operation of the image forming unit is well known, detailed description thereof is omitted.

  The recording material P is fed out one by one from the cassette 102 by the rotation of the roller 105, and this recording material is conveyed to the secondary transfer nip formed by the belt 123 and the secondary transfer roller 121 by the rotation of the roller 106. The recording material P onto which the unfixed toner image has been transferred at the secondary transfer nip is sent to the fixing unit 109, and the toner image is heated and fixed to the recording material at the fixing unit.

  The recording material P exiting the fixing unit 109 is discharged onto the tray 112 by the rotation of the roller 111.

(2) Fixing unit (fixing device) 109
A fixing device constituting the fixing unit 109 will be described. FIG. 2A is a cross-sectional view illustrating a schematic configuration of the fixing device 109 according to the present exemplary embodiment. FIG. 2B is a front view of the fixing device 109 according to the present embodiment as viewed from the upstream side in the recording material conveyance direction. FIG. 2C is a diagram illustrating a schematic configuration of the ceramic heater 15 of the fixing device 109 according to the present embodiment.

  The fixing device 109 includes a heating unit 10 and a pressure roller 30 as a pressure member. The heating unit 10 includes a tubular film (endless film) 16, a film guide 19 as a support member, a ceramic heater (heat source) 15 as a nip portion forming member, and the like. A film 16, a film guide 19, a ceramic heater (hereinafter referred to as a heater) 15, and a pressure roller 30 are all in a direction (hereinafter referred to as a longitudinal direction) orthogonal to the recording material conveyance direction (see FIG. 2A). It is a long member.

  A heater 15 is supported on the film guide 19, and a film 16 is loosely fitted on the film guide. By sandwiching the film 16 between the heater 15 and the pressure roller 30, a nip portion N is formed by the film and the pressure roller.

  Hereinafter, each member will be described in more detail. The pressure roller 30 has a round shaft-shaped cored bar (shaft portion) 30A made of a metal material such as iron, SUS, or aluminum. An elastic layer 30B mainly composed of silicone rubber or the like is formed in a roller shape on the outer peripheral surface between the support shaft portions 30A1 (see FIG. 2B) at both ends in the longitudinal direction of the core metal 30A. Further, a release layer 30C mainly composed of PTFE, PFA, FEP or the like is formed on the outer peripheral surface of the elastic layer 30B.

  The support shaft portions 30A1 at both ends in the longitudinal direction of the cored bar 30A are rotatably supported by bearings 41 on left and right side plates 40 that constitute a part of the metal frame 39 of the fixing device 109.

  The film guide 19 is formed in a substantially concave shape in cross section using a predetermined heat resistant material. On the flat surface of the film guide 19 on the pressure roller 30 side, a groove 19A is formed along the longitudinal direction, and the heater 15 is supported by this groove.

  The heater 15 includes a thin plate-like substrate 15A mainly composed of ceramic such as alumina or aluminum nitride. On the film sliding surface on the film 16 side of the substrate 15A, a heating resistor 15B mainly composed of silver, palladium or the like is pattern-printed along the longitudinal direction of the substrate. Further, a conductive portion 15C for energizing the heating resistor 15B and an electrode portion 15D for supplying power to the heating resistor via the conductive portion are printed on the film sliding surface. Further, a protective layer 15E mainly composed of a heat-resistant resin such as glass, fluorine resin, or polyimide is provided on the film sliding surface so as to cover the heating resistor 15B.

  The film 16 is formed in a cylindrical shape so that the inner peripheral length of the film is longer than the outer peripheral length of the film guide 19 and is loosely fitted to the film guide without tension. As the layer structure of the film 16, a two-layer structure is adopted in which the outer peripheral surface of an endless strip-shaped base layer mainly composed of polyimide is covered with an endless strip-shaped surface layer composed mainly of PFA.

  The film 16 fitted on the film guide 19 is arranged in parallel with the pressure roller 30, and both ends in the longitudinal direction of the film guide are urged by a pressure spring 42 in a horizontal direction perpendicular to the direction of the bus of the pressure roller. ing. The heater 15 supported by the film guide 19 brings the film 16 into contact with the outer peripheral surface (surface) of the pressure roller 30 in a pressurized state by the pressure of the pressure spring 42. As a result, the elastic layer 30B of the pressure roller 30 is crushed and elastically deformed, and a nip portion N (see FIG. 2A) having a predetermined width is formed between the surface of the pressure roller and the outer peripheral surface (surface) of the film 16. .

  In FIG. 2A, reference numeral 43 denotes a guide for guiding the recording material P to the nip portion N. Reference numeral 44 denotes a guide for guiding the recording material P discharged from the nip portion N.

  With reference to FIGS. 2A and 2C, the heat fixing processing operation of the fixing device 109 will be described. A driving force of a motor (not shown) provided in the image forming apparatus is transmitted to a gear (not shown) provided at a longitudinal end portion of the core metal 30A of the pressure roller 30, whereby the pressure roller rotates in the arrow direction. To do. The film 16 rotates in the direction of the arrow following the rotation of the pressure roller while the inner peripheral surface (inner surface) of the film slides on the protective layer 15E of the heater 15.

  The heating resistor 15B of the heater 15 is energized from the commercial power supply 203 through the triac 202, whereby the heating resistor generates heat and the heater is heated. The triac 202 is controlled by a CPU and a memory such as a RAM and a ROM so that the detected temperature of the temperature detecting element 201 that monitors the temperature of the non-sliding surface (back surface) of the substrate 15A maintains the fixing temperature (target temperature). Controlled by the unit 200.

  The recording material P carrying the unfixed toner image T is guided to the nip portion N by the guide 43. While the recording material P is nipped and conveyed at the nip portion N, the heat of the heater 15 and the pressure of the nip portion are applied to the unfixed toner image, whereby the toner image is heated and fixed on the recording material. The recording material P that has exited the nip portion N is guided by the guide 44 and fed to the roller 111.

(3) Explanation of small-diameter particles by release wax contained in toner The release wax is included in the toner of the unfixed toner image T carried by the recording material P. As described above, most of the release wax adheres after being transferred to the recording material P together with the molten toner image T, but a part of the release wax is vaporized into a gaseous state. The vaporized release wax component floats in the fixing device 109 as a small particle having a liquid phase or solid phase diameter of 0.1 μm or less depending on the ambient temperature. At this time, by allowing the small-diameter particles to float in the fixing device 109 for a long time, the small-diameter particles can be aggregated with each other or can be captured by surrounding members and the number of small-diameter particles discharged can be reduced.

(4) Description of the gap between the film and the core of the pressure roller in the fixing device of the comparative example FIG. 3A is a longitudinal end portion of the film 16 and the pressure roller 30 of the fixing device 109 according to the comparative example. It is sectional drawing of the longitudinal direction edge part vicinity. FIG. 3B is a cross-sectional view of the fixing device 109 according to the comparative example taken along one-dot chain line S0 in FIG. FIG. 3C is a cross-sectional view of the fixing device 109 according to the comparative example taken along one-dot chain line S1 in FIG.

  The release layer 30C and the elastic layer 30B of the pressure roller 30 are soft, and there is a possibility that the pressure roller 30 may be damaged or damaged when it is rubbed against a surrounding member. Therefore, in order to prevent the release layer 30C and the heater 15 from rubbing, the release layer is outside the end face 16A of the film in the longitudinal direction even if the thermal expansion, dimensional tolerance, or rattling of the pressure roller and the film is taken into consideration. The length of the pressure roller in the longitudinal direction is determined so as not to protrude.

  In this way, the lengths in the longitudinal direction of the release layer 30C and the elastic layer 30B are limited to be short, so that as shown in FIG. In general, the layer protrudes outside without contacting the layer. Therefore, a gap V corresponding to the thickness of the release layer and the elastic layer is formed between the core metal 20A and the film 16 protruding outward from the release layer 30C and the elastic layer 30B. Accordingly, a gap V is formed between the metal core 20 </ b> A and the film 16 on both sides in the longitudinal direction of the pressure roller 30.

  Here, the gap V is defined as follows in the cross section in the nip portion N formation region indicated by the broken line S1 in FIG. That is, the surface formed by the elastic layer 30B and the release layer 30C inside the two tangent lines b1 and b2 connecting the outer peripheral surface of the core metal 30A and the outer peripheral surface of the film 16 (the hatched portion indicated by M in FIG. 3C) ) Is defined as a gap area V when the space area is extended to the end face 16A of the film.

  Subsequently, the relationship between the gap region V and the airflow will be described with reference to FIG. When the recording material P is conveyed, the air around the recording material P is moved by the viscosity of the air. As a result, the air in the fixing device 109 tends to flow from the recording material introduction port I of the fixing device to the recording material discharge port O. That is, the air in the fixing device 109 tends to flow from the recording material introduction port I on the upstream side of the gap region V to the recording material discharge port O on the downstream side in the recording material conveyance direction. Further, the air around the pressure roller 30 and the film 16 also moves with the rotation of the pressure roller and the film.

  In the fixing device 109 of this comparative example, for example, the air around the surface of the film 16 and the outer peripheral surface (surface) of the core metal 30A of the pressure roller 30 is moved.

  In the gap region V, air around the surface of the film 16 and the surface of the core 30A is collected, and an air flow a3 is generated while gradually changing the direction. Specifically, in the gap region V, the movement direction a1 of the surface of the film 16 and the movement direction a2 of the surface of the cored bar 30A coincide, and an air flow a3 from the recording material introduction port I to the recording material discharge port O is generated. To do. That is, the air flow accompanying the conveyance of the recording material P coincides with the direction of the air flow a3 in the gap region V, and the air flow from the recording material introduction port I toward the recording material discharge port O increases.

  Further, as the outlet on the downstream side in the recording material conveyance direction of the nip surface formed in the vertical direction between the surface of the pressure roller 30 and the surface of the film 16 in the nip portion N approaches the vertical upward direction, the upward upward movement due to heat increases. It also coincides with the direction of airflow. Therefore, the air flow from the recording material introduction port I toward the recording material discharge port O becomes larger.

  Thus, the presence of the gap regions V on both sides in the longitudinal direction of the pressure roller 30 strengthens the action of pushing the air in the fixing device 109 together with the recording material P out of the image forming apparatus. As a result, the small-diameter particles generated in the fixing device 109 are discharged outside the fixing device in a short time, so that the aggregation of the small-diameter particles and the supplement to the surrounding members of the small-diameter particles do not occur sufficiently. May be discharged out of the fixing device.

(5) Description of Airflow Suppression Member FIG. 4A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to the present embodiment in the longitudinal direction and the vicinity of the longitudinal direction. FIG. 4B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along an alternate long and short dash line S2 in FIG.

  As shown in FIGS. 4A and 4B, the fixing device 109 suppresses the generation of airflow when the recording material P carrying the toner image is conveyed to the gap area V by the nip portion N. The airflow suppressing member 45 is provided. Specifically, a part of the bearing 41 protrudes into the gap region V, and a part of the bearing 41 functions as the airflow suppression member 45. In other words, the airflow suppression member 45 also serves as the bearing 41.

  The shape of the airflow suppression member 45 will be described. If the airflow suppression member 45 is rubbed strongly with the film 16, the film may be damaged. In order to prevent the film 16 from being damaged, it is necessary to fix the airflow suppression member 45 at a position at a distance greater than the thickness of the film from the heater 15. That is, the airflow suppression member 45 is preferably fixed at a position where the distance between the airflow suppression member and the heater 15 is larger than the thickness of the film 16. Thereby, since the film 16 does not receive force from both the airflow suppression member 45 and the heater 15 at the same time, the film is not damaged.

  In addition, a portion of the film 16 that protrudes outward in the longitudinal direction from the surface formed by the elastic layer 30B and the release layer 30C of the pressure roller 30 is lifted from the heater 15 by the rigidity of the film itself during the rotation of the film, thereby suppressing airflow. There is a possibility of contact with the member 45. However, since the distance between the airflow suppression member 45 and the heater 15 is larger than the thickness of the film 16, even if the portion contacts the airflow suppression member 45, it can escape to the heater 15 side, and the film 16 is damaged. Can be suppressed.

  Further, when the airflow suppressing member 45 is rubbed strongly with the release layer 30C and the elastic layer 30B of the pressure roller 30, the release layer and the elastic layer may be damaged. In order to suppress breakage of the release layer 30C and the elastic layer 30B, the airflow suppression member 45 needs to be prevented from coming into contact with the release layer and the elastic layer.

  In this embodiment, the airflow suppression member 45 has a rectangular parallelepiped shape. 4A, the distance between the airflow suppression member 45 and the film 16 is 0.5 mm, and the distance between the airflow suppression member 45 and the elastic body 30B is 0.5 mm. Further, the entire surface of the airflow suppression member 45 was brought into contact with the surface of the core metal 30 </ b> A in the longitudinal direction of the pressure roller 30.

  An experiment was performed on the number of small-diameter particles discharged for the fixing device 109 of this embodiment. For the fixing device 109 of the comparative example, an experiment was performed on the number of small-diameter particles to be discharged. Further, in the fixing device 109 of this embodiment, the small-diameter particles that are discharged also when the airflow suppression member 45 is provided only on the left side in the longitudinal direction of the pressure roller 30 and when provided on both sides in the longitudinal direction of the pressure roller 30. A number of experiments were performed. Further, in each of the fixing devices 109 of the present embodiment and the comparative example, an experiment was performed on the number of small diameter particles to be discharged even when the angle of the fixing device was changed.

  Specifically, the angle of the nip portion N of the nip portion N with respect to the installation surface of the image forming apparatus is 0 degree and 90 degrees (the direction in which the outlet on the downstream side of the recording material conveyance direction of the nip portion N faces upward) The configuration is as follows.

  Then, the evaluation method of the discharge | emission number of small diameter particles is demonstrated. In the evaluation method, the inside of a sealed chamber of 3 cubic meters is filled with purified air, an image forming apparatus is installed in the chamber, and an image with a printing rate of 5% is measured for 10 minutes after measuring a small particle size concentration. did. For the measurement, a nanoparticle size distribution measuring instrument FMPS3091 (manufactured by TSI) was used.

  Table 1 shows the concentration under each condition when the measured value of the small particle concentration is 1 in Comparative Example 1 (a configuration in which the airflow suppression member 45 is not provided and the angle of the nip surface is 90 degrees with respect to the horizontal plane).

  From Table 1, the fixing device 109 of the present embodiment (providing the airflow suppression member on the left and right, or only on the left and right) provides the airflow suppression member 45 in the gap region V, thereby reducing the number of discharged small-diameter particles. I was able to suppress it. Further, in the fixing device 109 having the configuration in which the airflow suppression members 45 are provided not on the left side in the longitudinal direction but in the gap region V on both the left and right sides in the longitudinal direction of the pressure roller 30, the suppression ratio of the discharge number of small diameter particles is further increased. You can see that it ’s big. Further, it can be seen that in the fixing device 109 configured such that the exit of the nip portion N faces upward, the ratio of suppressing the number of small-diameter particles discharged is larger.

  Although not shown in Table 1, even in the fixing device 109 configured such that the angle of the nip portion N of the nip portion N with respect to the horizontal plane is between 0 degrees and 90 degrees, the number of discharged small-diameter particles can be suppressed, It was confirmed that the suppression ratio increases as the angle increases.

  That is, in the configuration of the present embodiment, the effect of suppressing the discharge number of small-diameter particles is greater when the recording material discharge direction at the nip N has a component that is vertically upward with respect to the installation surface of the image forming apparatus.

  Since the fixing device 109 according to this embodiment includes the airflow suppression member 45 in the gap region V, the airflow suppression member can shield the gap region, and the air in the fixing device accompanying the conveyance of the recording material P is imaged together with the recording material. The action of extruding out of the apparatus can be weakened. As a result, the generation of the air flow a3 from the recording material introduction port I toward the recording material discharge port O can be suppressed, and the flow of air in the fixing device 109 can be reduced. As a result, it is possible to lengthen the time until the small diameter particles generated in the fixing device 109 are discharged out of the fixing device.

  Therefore, the small-diameter particles are easily aggregated and the small-diameter particles are easily collected around the small-sized particles before the small-sized particles are discharged to the outside of the fixing device 109, and the number of small-sized particles discharged to the outside of the fixing device can be reduced. There is an effect.

  It is more effective if the airflow suppression member 45 is provided in the gap region V on both sides in the longitudinal direction of the pressure roller 30. In the case where one of the gap areas V on both sides in the longitudinal direction of the pressure roller 30 is not sufficiently shielded, the air flow is concentrated there, and the number of small-diameter particles discharged cannot be reduced without the air flow rate being lowered. There is.

  In the fixing device 109 of this embodiment, since the airflow suppression member 45 also serves as the bearing 41, the above-described effects can be obtained without increasing the size of the fixing device 109 or the image forming apparatus itself.

[Example 2]
FIG. 5 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 5A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 5B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along one-dot chain line S3 in FIG.

  The fixing device 109 according to the first embodiment is configured such that the entire surface of the airflow suppression member 45 is brought into contact with the surface of the core metal 30 </ b> A in the longitudinal direction of the pressure roller 30. The fixing device 109 shown in this embodiment has the same configuration as that of the fixing device of Embodiment 1 except that a part of the airflow suppression member 45 is not brought into contact with the surface of the core metal 30A in the longitudinal direction of the pressure roller 30. It is as.

  As shown in FIG. 5A and FIG. 5B, the airflow suppression member 45 is a core metal facing surface (axis) that does not contact the surface of the core metal 30A with a part of the airflow suppression member in the longitudinal direction of the pressure roller 30. Part facing surface) 45A. With this configuration, it is possible to reduce the discharge amount of small-diameter particles to the outside of the apparatus while suppressing an increase in driving torque of the pressure roller 30 by reducing an area where the airflow suppressing member 45 and the core metal 30A slide. Furthermore, with this configuration, generation of rubbing noise between the core metal 30A and the airflow suppression member 45 can be suppressed.

[Example 3]
FIG. 6 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 6A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 6B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along a dashed line S4 in FIG.

  The fixing device 109 according to the present embodiment has the same configuration as the fixing device according to the first embodiment, except that the airflow suppression member 45 also serves as the guide 43.

  As shown in FIGS. 6A and 6B, a part of the guide 43 protrudes into the gap region V, and a part of the guide 43 functions as the airflow suppression member 45. In other words, the airflow suppression member 45 also serves as the guide 43.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45 is provided in the gap region V, the effect described in the first embodiment can be obtained. In addition, since the airflow suppression member 45 also serves as the guide 43, the above-described effects can be obtained without increasing the size of the fixing device 109 or the image forming apparatus itself.

  In this embodiment, the guide 43 and the airflow suppression member 45 are integrally formed. However, the guide and the airflow suppression member are separately formed of different materials, and the guide and the airflow suppression member are integrally coupled. You may make it make it. For example, the resin airflow suppressing member 45 and the metal guide 43 may be integrally coupled using a connecting member such as a screw.

[Example 4]
FIG. 7 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 7A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 7B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along a dashed-dotted line S5 in FIG.

  The fixing device 109 of the present embodiment has the same configuration as that of the fixing device of the first embodiment, except that the airflow suppressing member 45 also serves as the guide 44.

  As shown in FIG. 7A and FIG. 7B, a part of the member of the guide 44 protrudes into the gap region V, and a part of the guide 44 functions as the airflow suppressing member 45. In other words, the airflow suppression member 45 also serves as the guide 43.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45 is provided in the gap region V, the effect described in the first embodiment can be obtained. In addition, since the airflow suppression member 45 also serves as the guide 44, the above-described effects can be obtained without increasing the size of the fixing device 109 or the image forming apparatus itself.

  In this embodiment, the guide 44 and the airflow suppressing member 45 are integrally formed. However, the guide and the airflow suppressing member are separately formed of different materials, and these guides and the airflow suppressing member are integrally coupled. You may make it make it. For example, the resin airflow suppressing member 45 and the metal guide 44 may be integrally coupled using a connecting member such as a screw.

[Example 5]
FIG. 8 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 8A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 8B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along one-dot chain line S6 in FIG.

  The fixing device 109 according to the present embodiment has the same configuration as the fixing device according to the first embodiment, except that the airflow suppressing member 45 also serves as the frame 39.

  As shown in FIGS. 8A and 8B, a part of the member of the frame 39 protrudes into the gap region V, and a part of the frame 39 functions as the airflow suppressing member 45. In other words, the airflow suppression member 45 also serves as the frame 39.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45 is provided in the gap region V, the effect described in the first embodiment can be obtained. Further, since the airflow suppression member 45 also serves as the frame 39, the above-described effects can be obtained without increasing the size of the fixing device 109 or the image forming apparatus itself.

  In the present embodiment, an example in which the frame 39 and the airflow suppression member 45 are integrally formed has been described. However, the frame and the airflow suppression member are separately formed of different materials, and the frame and the airflow suppression member are integrally coupled. You may make it make it. For example, the resin airflow suppressing member 45 and the metal frame 39 may be integrally coupled using a connecting member such as a screw.

[Example 6]
FIG. 9 is an explanatory diagram of the fixing device 109 according to the present embodiment. FIG. 9A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 9B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along a dashed line S7 in FIG.

  In the fixing device 109 according to the first to fifth embodiments, the example in which a part of the stationary member such as the bearing 41, the guide 43, the guide 44, the frame 39, and the like does not move is used as the airflow suppression member 45 has been described. The fixing device 109 according to the present exemplary embodiment has the same configuration as the fixing device according to the first exemplary embodiment except that the airflow suppression member 45R is formed on a part of the pressure roller 30 and is rotated together with the pressure roller. It is as.

  The fixing device 109 of the present embodiment also has an airflow suppression member 45R in the gap region V. Specifically, the airflow suppression member 45 </ b> R is formed on the surface of the core metal 30 </ b> A of the pressure roller 30. A part of the airflow suppression member 45R enters the gap region V.

  The shape of the airflow suppression member 45R will be described. If the airflow suppressing member 45R is rubbed strongly with the film 16, the film 16 may be damaged. In order to prevent the film 16 from being damaged, the airflow suppression member 45R needs to be fixed at a position at a distance greater than the thickness of the film from the heater 15. That is, the airflow suppression member 45 is preferably fixed at a position where the distance between the airflow suppression member and the heater 15 is larger than the thickness of the film 16. Moreover, since the airflow suppression member 45R is rotated with the core metal 30A of the pressure roller 30, the airflow suppression member may be in contact with the release layer 30C and the elastic layer 30B.

  In the present embodiment, the airflow suppressing member 45R has a ring shape, and the airflow suppressing member 45R is fitted and fixed to the cored bar 30A. In FIG. 9A, the distance between the airflow suppression member 45R and the film 16 is set to 0.5 mm. The airflow suppressing member 45R and the elastic body 30B, and the airflow suppressing member 45R and the cored bar 30A are in contact with each other.

  The airflow suppression member 45R is formed of a material having a smaller volumetric specific heat than the core metal 30A. Thereby, the heat capacity of the airflow suppressing member 45R can be made smaller than that of the core metal 30A. As a result, when the nip portion N is heated to the fixing temperature, the amount of heat absorbed by the airflow suppression member 45R can be reduced, and energy saving of the fixing device 109 can be achieved. In this embodiment, a resin member having a volume specific heat smaller than that of iron, which is a material of the core metal 30A, is used as the material of the airflow suppressing member 45R.

  The experiment of the number of small-diameter particles to be discharged was also performed on the fixing device 109 of this embodiment. The experimental method for the experiment and the method for evaluating the number of discharged small-diameter particles are the same as in Example 1. The results are shown in Table 2.

  From the experimental results shown in Table 2, in any fixing device 109 of this embodiment, the number of small-diameter particles discharged can be suppressed by providing the airflow suppression member 45R in the gap region V. In addition, in the fixing device 109 having the configuration in which the airflow suppression member 45R is provided on both sides in the longitudinal direction of the gap region V on both sides in the longitudinal direction of the pressure roller 30, the suppression rate of the discharge number of small diameter particles is larger. I understand. Further, it can be seen that in the fixing device 109 configured such that the exit of the nip portion N faces upward, the ratio of suppressing the number of small-diameter particles discharged is larger.

  Although not shown in Table 2, even in the fixing device 109 configured such that the angle of the nip portion N of the nip portion N with respect to the horizontal plane is between 0 degrees and 90 degrees, the number of discharged small-diameter particles can be suppressed, It was confirmed that the suppression ratio increases as the angle increases.

  Since the fixing device 109 of the present embodiment also includes the airflow suppression member 45R in the gap region V, the effect described in the first embodiment can be obtained. Further, since the airflow suppression member 45R is fixed to the core metal 30A of the pressure roller 30, the above-described effects can be obtained without increasing the size of the fixing device 109 or the image forming apparatus itself.

[Example 7]
FIG. 10 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 10A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 10B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along one-dot chain line S8 in FIG.

  The fixing device 109 according to the present embodiment has the same configuration as that of the sixth embodiment except that a part of the elastic body 30B of the pressure roller 30 also serves as the airflow suppressing member 45R.

  As shown in FIGS. 10A and 10B, a part of the elastic body 30B of the pressure roller 30 protrudes into the gap region V, and a part of the elastic body 30B functions as the airflow suppression member 45R. doing. In other words, a part of the elastic body 30B also serves as the airflow suppression member 45R.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45R is provided in the gap region V, the effect described in the sixth embodiment can be obtained. In addition, since a part of the elastic body 30B of the pressure roller 30 also serves as the airflow suppression member 45R, the above-described effects can be obtained without increasing the size of the fixing device 109 or the image forming apparatus itself.

[Example 8]
FIG. 11 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 11A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 11B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along a dashed line S9 in FIG.

  The fixing device 109 according to the present embodiment has the same configuration as that of the sixth embodiment except that a part of the core metal 30A of the pressure roller 30 also serves as the airflow suppression member 45R.

  As shown in FIGS. 11A and 11B, a part of the core metal 30A of the pressure roller 30 protrudes into the gap region V, and a part of the core metal 30A functions as the airflow suppression member 45R. doing. In other words, a part of the core metal 30A also serves as the airflow suppression member 45R.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45R is provided in the gap region V, the effect described in the sixth embodiment can be obtained. In addition, since a part of the core metal 30A of the pressure roller 30 also serves as the airflow suppressing member 45R, the above-described effects can be obtained without increasing the size of the fixing device 109 or the image forming apparatus itself.

[Example 9]
FIG. 12 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 12A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 12B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along a dashed-dotted line S10 in FIG.

  The fixing device 109 according to the present embodiment is configured such that the outer diameter of the support shaft portion 30A1 of the core 30A of the pressure roller 30 is smaller than that of the core 30A of the pressure roller 30 according to the first to eighth embodiments. The configuration is the same as that of the fixing device of the first embodiment.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45 is provided in the gap region V, the effect described in the first embodiment can be obtained. Further, since the outer diameter of the support shaft portion 30A1 of the core metal 30A of the pressure roller 30 is smaller than that of the core metal 30A of the pressure roller 30 of the first embodiment, the air current is suppressed when the nip portion N is heated to the fixing temperature. The amount of heat absorbed by the member 45 is reduced, and energy saving of the fixing device 109 can be achieved. If the configuration of the fixing device 109 of this embodiment is applied to the fixing devices of Embodiments 2 to 8, energy can be saved in the fixing device of each of the embodiments.

[Example 10]
FIG. 13 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 13A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to this embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 13B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along a dashed line S11 in FIG.

  The fixing device 109 of this embodiment has a point that a halogen heater 60 as a heat source is provided inside the film 16, and that a nip forming member 15 formed of a metal having high thermal conductivity such as aluminum is used instead of the heater 15. Except for this, the configuration is the same as that of the fixing device of the first embodiment. The film 16 is heated by the halogen heater 60 through the nip forming member 15.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45 is provided in the gap region V, the effect described in the first embodiment can be obtained. The configuration of the fixing device 109 according to this embodiment may be applied to the fixing devices according to the second to eighth embodiments.

  The halogen heater 60 is not limited to the inside of the film 16 and may be disposed outside the film 16 to heat the surface of the film 16. A configuration in which the halogen heater 60 is not required may be employed by using the self-heating type film 16.

[Example 11]
FIG. 14 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 14A is a cross-sectional view of the film 16 and the pressure roller 30 of the fixing device 109 according to the present embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 14B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along a dashed-dotted line S12 in FIG.

  The fixing device 109 of this embodiment uses a nip forming member 15 formed of a resin with low friction instead of the heater 15 of the heating unit 10. The metal core 30A of the pressure roller 30 has a hollow structure, and a halogen heater 61 is disposed inside the metal core as a heat source. The halogen heater 61 heats the pressure roller from the inside of the pressure roller 30. The recording material carries an unfixed toner image on the surface on the pressure roller 30 side and is introduced into the nip portion N. Except for these points, the fixing device 109 of the present embodiment has the same configuration as the fixing device of the first embodiment.

  Also in the fixing device 109 of the present embodiment, since the airflow suppression member 45 is provided in the gap region V, the effect described in the first embodiment can be obtained. The configuration of the fixing device 109 according to this embodiment may be applied to the fixing devices according to the second to eighth embodiments.

[Example 12]
FIG. 15 is an explanatory diagram of the fixing device 109 according to this embodiment. FIG. 15A is a cross-sectional view of the film 16, the pressure roller 30, and the second film 16 </ b> E in the fixing device 109 according to the present embodiment in the longitudinal direction and the vicinity of the longitudinal direction end. FIG. 15B is a cross-sectional view of the fixing device 109 according to the present embodiment taken along one-dot chain line S12 in FIG.

  The fixing device 109 of this embodiment uses a nip forming member 15 formed of a resin with low friction instead of the heater 15 of the heating unit 10. A second heating unit 10E is provided on the side of the pressure roller 30 opposite to the heating unit 10. The recording material carries an unfixed toner image on the surface on the pressure roller 30 side and is introduced into the nip portion N. Except for these points, the fixing device 109 of the present embodiment has the same configuration as the fixing device of the first embodiment.

  The second heating unit 10E has the same configuration as the heating unit 10, and has a cylindrical second film 16E, a second film guide 19 as a second support member, and a second nip portion forming member. Second ceramic heater (hereinafter referred to as a heater) 15E. By elastically deforming the elastic layer 30B of the pressure roller 30 through the second film 16E by the second heater 15E, the second pressure roller surface and the second film surface have a second width of a predetermined width. A nip portion NE is formed. Then, the second heater 15E heats the surface of the pressure roller 30 through the second cylindrical film 16E at the second nip portion NE.

  In the fixing device 109 of this embodiment, the second film 16E rotates in the direction of the arrow following the rotation of the pressure roller 30E. Accordingly, as shown in FIG. 15B, in the gap VE formed between the core 30A of the pressure roller 30 and the second film 16, the movement direction a1E of the surface of the second film 16E and the pressure roller 30 The moving direction a2E of the surface of the metal core 30A matches. For this reason, an air flow a3E from the recording material discharge port O to the recording material introduction port I is generated.

  Since the air flow a3E is in a direction that cancels the air flow that moves with the recording material P, the air flow suppressing member 45h provided in the gap region V causes the small-diameter particles to move out of the image forming apparatus more effectively than the fixing device 109 of the first embodiment. The number of discharges can be reduced.

  The configuration of the fixing device 109 according to this embodiment may be applied to the fixing devices according to the second to eighth embodiments.

[Example 13]
(1) Configuration of Fixing Device The fixing device according to this embodiment will be described with reference to FIGS. 16 (a), 16 (b) and FIG. This fixing device is a film heating type fixing device (fixing device) mounted on a printer (image forming apparatus) using an electrophotographic recording technique.

  16A is a cross-sectional view showing a schematic configuration of the fixing device, and FIG. 16B is a front view of the fixing device shown in FIG. 16A from the upstream side in the recording material conveyance direction. In FIG. 16B, for convenience of explanation, the cover 500 is shown cut at the center in the short direction. FIG. 17 is a diagram illustrating a schematic configuration of the heater 2 of the fixing device.

  The fixing device forms a tubular film (rotating body) 100, a heater (heating body) 200 that contacts the inner peripheral surface (inner surface) of the film and heats the film, and a nip portion N via the heater and the film. A pressure roller (pressure member) 300 is provided. Further, the fixing device includes a holder (supporting member) 400 that supports the heater 200, a cover 500 that covers the outer peripheral surface (front surface) of the film 1, two flanges (holding members) 600 that hold the ends of the film 100, and a holder. A stay 700 for reinforcing 400, and the like.

  The film 100, the heater 200, the pressure roller 300, the holder 400, the cover 500, and the stay 700 are all members that are long in the direction orthogonal to the recording material conveyance direction (hereinafter referred to as the longitudinal direction).

  The film 100 has a three-layer structure including a base layer 110, an elastic layer 120, and a surface layer 130. The base layer 110 is a cylindrical base layer that bears mechanical properties such as torsional strength and smoothness of the film 100, and is made of a resin such as polyimide or a metal such as SUS having high thermal conductivity, an alloy, or the like. The elastic layer 120 formed on the outer peripheral surface of the base layer 110 is made of silicone rubber or the like in order to improve followability to the recording material P such as recording paper. The elastic layer 120 may not be formed in consideration of cost and the like.

  The surface layer 130 formed on the outer peripheral surface of the elastic layer 120 is made of PFA or PTFE having good releasability so that dirt such as toner and paper powder is hardly attached.

  In this embodiment, the film 100 having an outer diameter of φ18 and a longitudinal length of 230 mm is used. The base layer 110 uses SUS having a thickness of 30 μm. The elastic layer 120 is made of silicone rubber having a thickness of 250 μm. The surface layer 130 used was a PFA coating treatment formed with a 30 μm release layer.

  The heater 200 has an elongated substrate 200A in the longitudinal direction. As the substrate 200A, an insulating ceramic substrate such as alumina or aluminum nitride, a heat resistant resin substrate such as polyimide, PPS, or liquid crystal polymer is used.

  A heating resistor 200B such as Ag / Pd (silver palladium) is linearly formed by screen printing or the like on the inner surface of the substrate 200A (hereinafter referred to as a film sliding surface) along the longitudinal direction of the substrate. Or it is coated and formed in the shape of a narrow strip. Further, on the film sliding surface on the film 100 side of the substrate 200A, a conductive part 200C for energizing the heating resistor 2B and an electrode 200D for supplying power to the heating resistor via this conductive part are obtained by screen printing or the like. It is coated and formed in a narrow strip shape.

  Further, an insulating protective layer 200E made of, for example, glass or polyimide resin is formed on the film sliding surface of the substrate 2A so as to cover the heating resistor for the purpose of protecting the heating resistor 200B and ensuring insulation. is there.

  A temperature detection element 800 such as a thermistor is in contact with the surface of the substrate 200A opposite to the film sliding surface (hereinafter referred to as a film non-sliding surface) at the center in the longitudinal direction of the substrate.

  In this embodiment, the heater 200 is made of alumina as the material of the substrate 2A, the Ag / Pd heating resistor 2B is formed on the substrate, and the insulating protective layer 2E made of glass is further formed. . The size of the substrate 200A is 5.83 mm in the direction parallel to the recording material conveyance direction (hereinafter referred to as the short direction), 270 mm in the longitudinal direction, and 1 mm in thickness.

  The pressure roller 300 has a metal core 310 made of a material such as iron or aluminum. An elastic layer 32 made of a material such as silicone rubber is formed on the outer peripheral surface between the shaft portions 310A at both ends in the longitudinal direction of the cored bar 310. Further, a release layer 330 made of a material such as PFA is formed on the outer peripheral surface of the elastic layer 32. The hardness of the pressure roller 300 is 40 degrees at an Asker C-type hardness meter of 9.8 N (1 kgf load) so as to satisfy the width and durability of the fixing nip N portion, which will be described later, satisfying the fixing property. To 70 degrees is preferred.

  In the pressure roller 300, shafts 310A at both ends in the longitudinal direction of the cored bar 310 are rotatably supported by the frame F of the fixing device.

  In this embodiment, as the pressure roller 300, a silicone rubber layer is formed as an elastic layer 320 on a φ13 aluminum core 31 with a thickness of 3.5 t, and a release layer 330 is formed on the silicone rubber layer as a thickness of 40 μm. The one covered with a conductive PFA tube is used. The hardness is 60 degrees, the outer diameter is φ20, and the length of the elastic layer 320 in the longitudinal direction is 226 mm.

  The holder 400 is formed of a heat-resistant resin such as liquid crystal polymer, PPS, or PET in a substantially concave shape in cross section. The holder 400 supports the heater 2 by a groove 400A formed along the longitudinal direction on the flat surface of the holder on the pressure roller 300 side.

  The stay 7 is disposed on the flat surface of the holder 400 opposite to the groove 400A. This stay 700 is used to uniformly transmit the pressure applied to both ends of the stay in the longitudinal direction by a pressurizing spring 900 described later in the longitudinal direction of the holder 4. Therefore, rigidity is enhanced by using a rigid material such as iron, stainless steel, gin-coated steel plate, etc., and making the cross-sectional shape substantially U-shaped.

  The flange 600 disposed at the end of the film 1 in the longitudinal direction is formed of a heat resistant resin such as liquid crystal polymer, PPS, or PET. The flange 600 includes a restriction portion 600A for restricting the movement of the film 100 in the longitudinal direction and a support portion 600B for supporting the inner surface of the end portion of the film 1 in the longitudinal direction. The longitudinal end of the holder 400 and the longitudinal end of the stay 700 are supported by the restricting portion 600A of the flange 600, and the flange 600 is arranged in parallel with the film 100 and supported by the frame F via the restricting portion 600A. ing.

  The support portion 600B protrudes from the restriction surface 600A1 of the restriction portion 600A against which the film end abuts when the film 100 moves in the longitudinal direction, and supports the inner surface of the film 100.

  A pressure spring 900 disposed between the restriction portion 600 </ b> A of the flange 600 and the frame F presses both ends in the longitudinal direction of the stay 700 through the flange 600 in a direction orthogonal to the generatrix direction of the pressure roller 300. . As a result, the stay 700 presses both ends in the longitudinal direction of the holder 400 in the same direction, and presses the heater 200 against the surface of the pressure roller 300 via the film 100. As a result, the elastic layer 330 of the pressure roller 3 is crushed and elastically deformed, and a nip portion N (see FIG. 16A) having a predetermined width that is uniform in the longitudinal direction between the surface of the pressure roller 300 and the outer surface of the film 100. It is formed.

  In this embodiment, liquid crystal polymer is used as the material of the holder 400 and PET is used as the material of the flange 600. The length that the support portion 600B of the flange 600 supports the inner surface of the film 100 is 10 mm. As a material for the stay 700, a gin-coated steel plate is used. The pressure applied to the pressure roller 300 is 196 N (20 kgf), and at this time, a nip portion N width of 7 mm is obtained.

(2) Heat Fixing Processing Operation of Fixing Device Fixing processing will be described with reference to FIGS. 16 (a), 16 (b) and FIG. The driving force of the motor M is transmitted to the gear G provided at the longitudinal end of the core bar 310 of the pressure roller 300, whereby the pressure roller rotates in the direction of the arrow. The film 100 rotates in the direction of the arrow following the rotation of the pressure roller while the inner surface of the film 100 slides on the heater 200. In this embodiment, the recording material P is conveyed at a speed of 120 mm / sec by the rotation of the pressure roller 300 and the film 100.

  The heating resistor 200B of the heater 200 is energized from the commercial power supply 1030 via the triac 1020, whereby the heating resistor 200B generates heat and the heater is heated. The TRIAC 1020 has a CPU, RAM, ROM, etc. so that the detection temperature of the temperature detection element 8 that detects the temperature of the surface opposite to the surface in contact with the film 100 of the substrate 200A maintains the fixing temperature (target temperature) 230 ° C. It is controlled by the control unit 1000 comprising the above memory.

  The recording material P carrying the unfixed toner image T is introduced into the nip portion N. The recording material P is nipped and conveyed by the nip portion N, and the heat of the heater 200 and the pressure of the nip portion are applied to the unfixed toner image T. As a result, the toner image is heated and fixed on the recording material. Discharged.

(3) Description of Cover The cover 500 is made of a heat resistant resin such as PPS or PET. The cover 500 is formed in a substantially semicircular cross section so as to cover substantially the entire area other than the nip portion N across the circumferential direction of the surface of the film 100. The cover 500 is supported by the frame F at both ends in the longitudinal direction of the cover via a support member (not shown) such as a bracket, and covers the film in the vicinity of the film 100 so as not to let the heat generated by the heater 200 escape. It is installed as follows.

  Since both end portions in the longitudinal direction of the film 100 rotate while being supported by the support portion 600B of the flange 600, the outer surface of the film 100 is unlikely to swing in the radial direction. On the other hand, since the central portion in the longitudinal direction of the film can be rotated without being restricted except for the nip portion N, the outermost surface of the film is on the outer side at the opposite position farthest from the nip portion in the rotational direction of the film 100. Easily deforms by shaking.

  In the fixing device of the present embodiment, the shake amount in the longitudinal direction of the film 100 when the recording material P is conveyed by the nip portion N is shown in FIG. In FIG. 18, the support surface 600B1 (see FIG. 19B) that supports the inner surface of the film 100 directly below the center in the short direction of the cover 500 in the support portion 600B of the flange 600 is set as a reference (zero). At both ends in the longitudinal direction of the film 100, the inner surface of the film is supported by the flange 600, so that the amount of shake is close to zero, and the amount of shake is large at the central portion that is restricted only by the nip portion N.

  When the cover 500 comes into contact with the outer surface of the film 100, damage to the film or poor fixing due to the heat of the film 100 being taken away by the cover 500 occurs. It was arranged considering the amount of flare and part tolerance.

  In this embodiment, the shape of the cover 500 is optimized in consideration of the amount of shake in the longitudinal direction of the film 1 shown in FIG. For this reason, the cover 500 can be disposed closer to the film 100 than the conventional example.

  Here, FIG. 19A shows a cross section of the cover 500 of this embodiment. A virtual surface obtained by extending the support surface 600B1 of the support portion 600B of the flange 600 in the longitudinal direction is 600L. FIG. 19B is a diagram illustrating the shape of the cover 500 in the longitudinal direction.

  The radial distance of the film 100 between the virtual surface 600L at the position S2 farthest from the nip portion N in the rotation direction of the film 100 and the inner surface of the cover 500 in FIG. 19A is shown in FIG. The distance in the radial direction of the film 100 between the imaginary surface 600L and the inner surface of the cover 500 at four locations (1) to (4) from the end to the center in the longitudinal direction is shown. Comparative Example 3 and Comparative Example 4 have a configuration in which the distance is constant in the longitudinal direction.

  A dotted line and a solid line shown in FIG. 19A are the cross-sectional shape of the center portion and the cross-sectional shape of the end portion in the longitudinal direction of the cover 500 according to the embodiment 13, respectively. At the end of the cover 500, the distance between the inner surface of the cover 500 and the virtual surface 600L is shorter than that at the center. In the rotational direction of the film 100, the radial deflection of the outer surface of the film 100 is the largest at the position S2, so that the inner surface of the cover 500 is separated from the virtual surface 600L in the radial direction to increase the distance.

(3) Description of Small Diameter Particles from Release Wax Contained in Toner The release wax (hereinafter also referred to as toner wax) is included in the toner of the unfixed toner image T carried by the recording material P. As described above, most of the release wax adheres after being transferred to the recording material P together with the molten toner image T, but a part of the release wax is vaporized into a gaseous state. The vaporized release wax component floats in the fixing device as small particles having a liquid phase or solid phase diameter of 0.1 μm or less depending on the ambient temperature. At this time, by suspending the small-diameter particles in the fixing device for a long time, the small-diameter particles can be aggregated with each other or can be supplemented by surrounding members and the number of small-diameter particles discharged can be reduced.

  When the toner wax used in the image forming apparatus in which the fixing device of this embodiment is mounted is heated, small-diameter particles are generated from around 145 ° C. Therefore, in the image forming apparatus, examples of the generation source of the small diameter particles include the recording material P to which the toner wax adheres and the temperature becomes high, the surface of the film 100, and the surface of the pressure roller 300. FIG. 20 shows the temperatures of the recording material P, the surface of the film 100, and the surface of the pressure roller 300 when the recording material P is conveyed at the nip portion N under the conditions of this embodiment. From FIG. 20, since the only member having a temperature of 145 ° C. is the film 100, it is considered that the small-diameter particles are generated from the surface of the fixing film 1.

  The flow of air around the fixing film 100 will be described with reference to FIG.

  FIG. 21 is an enlarged view of portion A of the fixing device shown in FIG. 16A, and shows the flow of airflow generated around the film surface as the film 100 rotates.

  As shown in FIG. 21 (a), since the film 100 is moving in the direction indicated by the arrow a, it is influenced by the viscosity of the gas, and an air current as indicated by the arrow b is generated in the vicinity of the film 100. Yes. It is considered that the small diameter particles generated on the surface of the film 100 ride on this air stream and are discharged together with the recording material P to the outside of the fixing device. However, since the gas near the inner surface of the cover 500 that is stationary is also affected by the airflow due to the viscosity of the gas, the airflow is suppressed by bringing the cover 500 close to the film 100 as shown in FIG. Thus, the generated small-diameter particles can be easily retained inside the fixing device.

  In the fixing device of this embodiment, the shape of the cover 500 is set as follows in consideration of the change in the shape of the outer surface of the film 100 in the longitudinal direction when the recording material P is conveyed at the nip portion N. . That is, at the position opposite to the nip portion, the cover 500 is configured such that the end portion is shorter than the center portion in the longitudinal direction. Accordingly, it is possible to install the cover 5 closer to the film 1 than the comparative example 4 without bringing the film 100 and the cover 500 into contact with each other.

  Next, the results of evaluating the amount of small-diameter particles discharged outside the image forming apparatus using the image forming apparatuses on which the fixing devices of Comparative Example 3, Comparative Example 4, and the present embodiment are mounted will be described. The evaluation method is that in a N / N environment (temperature 23 ° C., humidity 50%), the sealed chamber of 3 cubic meters is filled with purified air, an image forming apparatus is installed in the chamber, and the toner printing rate is The small particle concentration after continuous printing of a 5% image for 10 minutes was measured. For the measurement, a nanoparticle size distribution measuring instrument FMPS3091 (manufactured by TSI) was used.

  As a result of the evaluation, the discharge amount of small-sized particles to the outside of the machine was reduced by 7% in this example compared with Comparative Example 4. In this embodiment, since the cover 500 can be disposed closer to the film 100 than in the comparative example 4, the airflow flowing between the cover 500 and the film 100 can be suppressed due to the influence of the viscosity of the airflow. It is. On the other hand, in Comparative Example 1, although the effect of reducing the small-diameter particles equal to or greater than that of the present example was observed, an image defect that seems to have contacted the film and the cover occurred.

  As described above, in the longitudinal direction as in the present embodiment, the shape of the cover 500 is such that the distance between the inner surface of the cover and the virtual surface 600L is shorter at the end than at the center. It becomes possible to arrange | position close to a film, without contacting. Thereby, discharge | emission to the exterior of the small diameter particle | grains generate | occur | produced from the film 100 surface can be suppressed. By allowing the small-diameter particles to float in the fixing device for a long time, the small-diameter particles agglomerate with each other or are trapped by surrounding members, so that the discharge amount to the outside of the apparatus can be suppressed.

  Further, in this embodiment, by adopting a simple configuration in which the shape of the cover 500 is changed without adding a new member, it is possible to suppress discharge of small diameter particles to the outside of the image forming apparatus.

  In the thirteenth embodiment, at the position S2 farthest from the nip portion in the rotation direction of the film 100, the distance between the inner surface of the cover 500 and the virtual surface 600L is shorter at the end portion than at the central portion in the longitudinal direction. However, as a modification of the thirteenth embodiment, the distance between the inner surface of the cover 500 and the virtual surface 600L may be shorter in the end portion than in the central portion in the longitudinal direction over the circumferential direction of the film 100. .

  FIG. 22A shows a cross section of the fixing device having this configuration. FIG. 22B shows the shape of the cover 5 in the longitudinal direction at the position S2 in FIG. 22A and the radial distance between the cover 500 and the virtual surface 600L. Further, FIG. 22C shows the radial distance between the inner surface of the cover 500 and the imaginary surface 600L at four positions (1) to (4) in the longitudinal direction at positions S1, S2, and S3 in the circumferential direction of the cover 500. Indicates.

  In this modification, the discharge amount of small-diameter particles to the outside of the machine could be reduced by 23% compared to Comparative Example 4 without bringing the cover 500 into contact with the film 100. That is, the present modification has a reduction effect of the discharge amount of small-diameter particles outside the machine about three times larger than that of the thirteenth embodiment. This is considered to be because the airflow flowing between the cover 500 and the film 100 could be suppressed more than in Example 13.

15: Ceramic heater, 16: Film, 30: Pressure roller, 30A: Metal core, 30B: Elastic layer, 39: Frame, 41: Bearing, 43, 44: Guide, 45: Airflow suppression member, 61: Halogen heater, 109: fixing device, P: recording material, T: unfixed toner image, V: gap

Claims (4)

A cylindrical film that contacts an unfixed toner image formed on the recording material;
A cover that covers the outer peripheral surface of the film over the longitudinal direction of the film;
A fixing device for fixing an unfixed toner image on a recording material using heat from the film,
As the distance between the outer peripheral surface and the cover of the end of the film in the longitudinal direction is smaller than the distance between the outer peripheral surface and the cover of the central portion of the film in the longitudinal direction, the cover Is provided so as to be curved toward the both end portions from the central portion in the longitudinal direction . A cylindrical film that contacts an unfixed toner image formed on the recording material;
A pressure roller in contact with the outer peripheral surface of the film;
A support surface that supports an inner surface of an end portion of the film in the longitudinal direction of the film, and a restriction portion that faces the end surface of the film in the longitudinal direction, and restricts movement of the film in the longitudinal direction. A regulating member that is provided one by one at positions corresponding to both end portions of the film in the longitudinal direction;
A cover that covers the outer peripheral surface of the film over the longitudinal direction of the film;
A fixing device that fixes an unfixed toner image on a recording material using heat from the film at a nip portion between the film and the pressure roller,
A distance between an imaginary line connecting positions farthest from the nip portion of the support surfaces of the two regulating members and an end portion of the cover in the longitudinal direction is the imaginary line. The cover is provided so as to be curved from the center in the longitudinal direction toward both ends so as to be smaller than the distance between the cover and the center of the cover in the longitudinal direction. apparatus. A cylindrical film that contacts an unfixed toner image formed on the recording material;
A cover that covers the outer peripheral surface of the film over the longitudinal direction of the film;
A fixing device for fixing an unfixed toner image on a recording material using heat from the film,
The fixing device, wherein the cover is curved so that a center portion in the longitudinal direction swells in a radial direction of the film rather than an end portion. Furthermore the device, fixing device according to any one of claims 1 to 3, characterized in that a heater in contact with the inner surface of the film.