JP2006058596A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device where a thin-wall fixing roller having higher strength and excellent durability is used, thus the further increase of pressurizing force is attained for increasing image quality and stabilizing fixing properties. <P>SOLUTION: A plurality of ribs 12 for preventing deformation are formed on the inner circumferential face of a thin fixing roller 11, and further, each rib 12 at the central part in the fixing roller 11 is internally provided with a ring-shaped reinforcing member 13. On the outer circumferential face of the ring-shaped reinforcing member 13, the inner shape of a recessed part 14 is formed matching the outer shape of each rib 12, and by joining the recessed part 14 to the rib 12, reinforcing effect is increased, and also, the separation of each reinforcing member 13 can be prevented. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device having a heating / fixing structure that is used in an apparatus using an electrophotographic process, such as an electrophotographic copying machine, a facsimile machine, and a printer, and performs fixing processing of a formed image.

  In recent years, in fixing devices mounted on image forming apparatuses such as copiers and printers, there is an increasing demand for shortening the apparatus warm-up time or saving energy. That is, there is a demand for a short time from when the apparatus is turned on until image formation is completed.

  In the current electrophotographic process, the toner image transferred onto the recording paper is passed through the nip between the fixing roller and the pressure roller of the fixing device together with the recording paper, and during that time heat is applied to the toner to cause melting. At the same time, the formed image is fixed on the recording paper by the pressure between the rollers.

  FIG. 9 is a longitudinal sectional view showing a schematic configuration of a conventional fixing device, FIG. 10 is a transverse sectional view showing a schematic configuration of the conventional fixing device, 1 is a fixing roller having a halogen heater 2 built in as a heating source, 3 Is a pressure roller disposed so as to be in pressure contact with the outer peripheral surface of the fixing roller 1.

  Conventionally, in order to speed up image fixing, it has been possible to shorten the warm-up time by preheating the fixing roller 1 or increasing the capability of a heating source such as the halogen heater 2. There is a demand for image fixing without waiting time while aiming for zero power consumption. As one of countermeasures, it is conceivable to reduce the thickness of the fixing roller 1 to accelerate heat transfer from the heating source inside the roller to the roller surface layer.

  However, when the wall thickness is reduced, the following problems occur.

  That is, the fixing roller 1 and the pressure roller 3 are combined by elastic urging means (not shown) at both ends thereof and pressed against each other. Therefore, the fixing roller 1 is deformed as the thickness of the fixing roller 1 is reduced. This main deformation is bending due to bending force and crushing due to being thin. This deformation is combined into a displacement on the lower surface of the roller, causing unevenness in the axial direction at the contact portion (nip) between the fixing roller 1 and the pressure roller 3, which causes a fixing defect.

  Here, the definition of crushing and bending is clarified. The crushing represents deformation in the roller cross section, and is, for example, a state in which a pipe having a perfect circular cross section is crushed into an ellipse (A state in FIG. 9: crushing amount = D1−D2). On the other hand, the bending is a bending and is a state when the straight pipe is bent with respect to the axial direction (state B in FIG. 10).

  In order to suppress the crushing and the bending, it has been proposed to reinforce the strength by providing convex portions (ribs) on the inner circumferential surface of the fixing roller 1 (see Patent Documents 1 to 3).

  By adopting such a structure, it is verified and implemented that the effect of reducing deformation is large, although the effect is small with respect to axial deformation (deflection).

  FIG. 11 is a cross-sectional view showing an example of a conventional thin-walled fixing roller with ribs. A plurality of ribs 5 for preventing deformation are formed on the inner peripheral surface of the fixing roller 1.

Further, as shown in FIG. 12, a structure has been proposed in which a ring-shaped reinforcing member 6 is provided inside the thin fixing roller 1 to suppress the deformation as described above.
JP-A-8-286541 JP-A-10-123868 JP 2002-196605 A

  In the prior art, in the rib 5 formed integrally with the roller metal core, it is difficult to increase the height of the rib due to the limitation of the manufacturing method. To increase the strength, the width of the rib 5 is increased. However, this method has a problem that the heat capacity of the entire roller is increased due to the presence of the ribs, and the merit of the thin wall is reduced.

  Further, in the case where the ring-shaped reinforcing member 6 is used to prevent the deformation of the roller, the reinforcing member 6 is merely provided inside, and therefore the reinforcing member 6 is inadvertently moved or detached. There is a problem in actual use.

  However, at present, further increase in pressure is desired to improve image quality and stabilize fixing properties.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve the above-described conventional problems and to provide a fixing device including a thin fixing roller having a structure having higher strength and superior durability.

  In order to achieve the above object, the invention according to claim 1 is a fixing device comprising a thin fixing roller having a heat source and a pressure roller in pressure contact with an outer peripheral surface of the fixing roller. A plurality of deformation-preventing ribs are formed on the inner peripheral surface of the roller, and at least one of the ribs is joined to the concave portion in a ring-shaped reinforcing member having a concave portion on the outer peripheral surface. With this configuration, the crushing strength of the conventional thin fixing roller with ribs can be further increased, and by reinforcing one or a plurality of ribs as appropriate, there is no excess or deficiency according to the applied pressure. Is possible. Further, by joining the outer peripheral surface of the reinforcing member to the rib as a recess, positioning of the reinforcing member is ensured, there is no fear of detachment, the characteristics are stable, and it can withstand long-term use. Therefore, the fixing roller can be reinforced more than before, and can be made thinner, the heat capacity can be reduced, and the rise time can be shortened. Further, the applied pressure can be increased, and the image quality, fixing property, and the like can be improved by using the image forming apparatus.

  According to a second aspect of the present invention, there is provided a fixing device comprising a thin fixing roller having a heat source and a pressure roller that is in pressure contact with the outer peripheral surface of the fixing roller. A plurality of prevention ribs are formed, and the outer peripheral surface of a ring-shaped reinforcing member is joined to at least one inner peripheral surface between the ribs. The crushing strength of the fixing roller can be further increased, and by appropriately setting and reinforcing at least one rib, reinforcement without excess or deficiency according to the applied pressure is possible. Further, by joining the outer peripheral surface of the reinforcing member to the inner peripheral surface of the fixing roller between the ribs, the positioning of the reinforcing member is ensured and there is no fear of detachment, the characteristics are stable, and it can withstand long-term use. Therefore, the fixing roller can be reinforced more than before, and can be made thinner, the heat capacity can be reduced, and the rise time can be shortened. Further, the applied pressure can be increased, and the image quality, fixing property, and the like can be improved by using the image forming apparatus.

  According to a third aspect of the present invention, in the fixing device according to the first or second aspect, the width of the reinforcing member is set so that the inner portion is narrower than the outer portion. The increase in the heat capacity due to the use can be minimized and the reinforcement efficiency can be increased.

  According to a fourth aspect of the present invention, in the fixing device according to the first or second aspect, a groove is formed on the inner side of the reinforcing member. With this configuration, the reinforcing member is used as described above. It is possible to minimize the increase in the heat capacity due to and increase the reinforcement efficiency.

  According to a fifth aspect of the present invention, in the fixing device according to any one of the first to fifth aspects, the longitudinal elastic modulus of the material of the reinforcing member is equal to or greater than the longitudinal elastic modulus of the core metal material of the fixing roller. This feature makes it possible to prevent loosening at the joint due to the difference in linear expansion during roller heating, eliminate the possibility that the reinforcing member will move or come off during use, and is structurally stable. .

  According to the fixing device of the present invention, the crushing strength of the conventional thin fixing roller with ribs can be further increased, and any part can be reinforced, so that there is no excess or deficiency according to the applied pressure. Is possible. In addition, since the positioning of the outer peripheral surface of the reinforcing member is ensured by using the ribs and the reinforcing member is not likely to come off, the characteristics are stable and it can withstand long-term use.

  Therefore, the fixing roller can be reinforced more than before, and can be made thinner, the heat capacity can be reduced, and the rise time can be shortened. Further, since the applied pressure can be increased, it is possible to improve the image quality, the fixing property, etc. by using the image forming apparatus.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view of a fixing roller for explaining the first embodiment of the present invention, FIG. 2 is an enlarged view of a portion A in FIG. 1, and the fixing roller of this embodiment is shown in FIGS. The fixing device shown in FIG.

  1 and 2, a plurality of deformation preventing ribs 12 are formed on the inner peripheral surface of the thin fixing roller 11, and in this example, every other rib 12 at the center of the roller is provided with a ring-shaped reinforcing member 13. There are three. On the outer peripheral surface of the ring-shaped reinforcing member 13, an inner shape concave portion 14 that substantially matches the outer shape of the rib 12 is formed. By joining the concave portion 14 so as to fit the rib 12, the reinforcing member 13 can be easily formed. So that it does n’t come off.

  As shown in FIG. 2, at the time of joining the rib 12 and the concave portion 14, the inclined portion of the peripheral portion of the rib 12 and the inner peripheral edge portion 14 a of the concave portion 14 of the reinforcing member 13 are in contact with each other. A gap 15 is formed between the central portions of 14. For this reason, in the joint portion between the rib 12 and the recess 14, slight wear occurs due to friction generated by rotating under pressure, but the apex of the rib 12 does not wear due to the presence of the gap 15, The reinforcing member 13 does not come off.

  Next, with reference to FIGS. 3A to 3E, a method for manufacturing the fixing roller of Embodiment 1 will be described.

  First, as shown in FIG. 3A, using a positioning jig 20, a ring-shaped reinforcing member 13 in which a concave portion 14 is formed is inserted into a cylindrical cored bar 21 that serves as the fixing roller 11, and is reinforced. The outer peripheral surface of the member 13 is kept in contact at a predetermined position on the inner peripheral surface of the cylindrical cored bar 21.

  In this state, as shown in FIG. 3B, the outer periphery of the cylindrical metal core 21 is press-deformed by the press jig 22 in the installation direction of the recess 14 of the reinforcing member 13.

  As shown in FIG. 3 (c), the pressing portion on the outer periphery of the cylindrical metal core 21 is depressed, and the rib 12 is formed on the inner circumferential surface of the cylindrical metal core 21 corresponding to the depressed portion. Will be projected so that the rib 12 fits into the recess 14.

  Next, as shown in FIG. 3 (d), the portion of the cylindrical metal core 21 including the recessed portion is shaved with a cutting jig 23, whereby the present embodiment as shown in FIG. The fixing roller 11 is completed.

  The formation positions and the number of ribs 12 and reinforcing members 13 are appropriately set according to the specifications of the fixing roller 11 (roller material, roller length, roller diameter, pressure, heating temperature, etc.). It is most effective as a countermeasure against deformation to be formed and reinforced.

  Further, in the fixing roller 11 having a diameter of 30 mm to 45 mm and a wall thickness t = 0.3 mm to 0.5 mm (see FIG. 2), the height h of the rib 12 is in the range of 0.3 mm to 0.6 mm with good workability. However, since the reinforcing member 13 can be increased in thickness T to about 3 mm to 5 mm, a high crushing strength can be obtained by providing the reinforcing member 13. As a result of the verification test, it was found that the width W should be about 3 mm to 5 mm in order to minimize the increase in heat capacity due to the reinforcing member 13.

  Although various shapes and structures of the ring-shaped reinforcing member of the present embodiment are conceivable, as shown in FIGS. 4 to 6, the width W of the reinforcing member 13 is an inner portion than the outer portion Wa. By making Wb narrower, the heat capacity of the reinforcing member 13 itself can be reduced, and the reinforcing efficiency can be improved.

  Furthermore, as shown in FIG. 7, by providing the groove 16 inside the reinforcing member 13, the heat capacity of the reinforcing member 13 itself can be reduced as described above, and the reinforcing efficiency can be improved.

  Further, by using the same material for the core metal of the fixing roller 11 and the material of the reinforcing member 13, it is possible to prevent loosening of the joint due to a difference in linear expansion during heating. When the metal core material is an aluminum alloy, the reinforcing material is made of steel or stainless steel, so that a slight looseness due to a difference in linear expansion occurs, but the reinforcing effect appears remarkably.

  FIG. 8 is a cross-sectional view showing the main part of the fixing roller for explaining the second embodiment of the present invention. The second embodiment is different from the first embodiment in that the fixing roller 11 between adjacent ribs 12 is shown. The outer peripheral surface of the reinforcing member 13 is joined to the inner peripheral surface of the reinforcing member 13. By doing so, the reinforcing member 13 is reinforced between the ribs 12 in a wider range than that of the first embodiment. It will be held firmly.

  Also in Embodiment 2, the installation location of the reinforcing member 13 is arbitrary, and may be installed between at least one or more ribs 12.

  As described above, according to the present embodiment, the crushing strength of the conventional fixing roller having a thin wall structure with ribs can be further increased. Reinforcement without any possible is possible.

  Further, when the rib is formed, the reinforcing member can be easily fixed by forming the convex rib in the concave portion of the outer peripheral portion of the reinforcing member.

  In addition, although the rib and the reinforcing member are joined at a certain amount of wear due to friction caused by rotation under pressure, the apex of the rib is worn due to the presence of a gap formed between the reinforcing member and the rib. Therefore, the reinforcing member will not come off.

  By installing such a reinforcing member inside the fixing roller, the thin fixing roller can be reinforced more than before, making it thinner, reducing heat capacity, and shortening the rise time. To do.

  Further, by mounting the fixing device employing the fixing roller of the present embodiment on the electrophotographic image forming apparatus, the pressure can be increased, so that the image quality and the fixability of the image forming apparatus can be improved.

  INDUSTRIAL APPLICABILITY The present invention is applied to a fixing device having a heating / fixing structure for fixing a formed image in an apparatus using an electrophotographic process, and particularly requires an increase in pressing force and has higher strength and superior durability. It is effective when applied to a thin fixing roller that requires a new structure.

1 is a cross-sectional view of a fixing roller for explaining Embodiment 1 of the present invention. Part A enlarged view in FIG. (A)-(e) is explanatory drawing which concerns on the manufacturing method of the fixing roller of Embodiment 1. FIG. Explanatory drawing of the shape and structure of Example 1 in the ring-shaped reinforcing member of this embodiment Explanatory drawing of the shape and structure of Example 2 in the ring-shaped reinforcing member of this embodiment Explanatory drawing of the shape and structure of Example 3 in the ring-shaped reinforcing member of this embodiment Explanatory drawing of the shape and structure of Example 4 in the ring-shaped reinforcing member of this embodiment FIG. 5 is a cross-sectional view showing a main part of a fixing roller for explaining Embodiment 2 of the present invention. A longitudinal sectional view showing a schematic configuration of a conventional fixing device Cross-sectional view showing a schematic configuration of a conventional fixing device Sectional view of a conventional thin fixing roller with ribs Sectional drawing which shows the principal part in the other example of the conventional thin fixing roller with a rib

Explanation of symbols

11 Fixing roller 12 Rib 13 Reinforcing member 14 Recess 14a Inner peripheral edge 15 Clearance 16 Groove 20 Positioning jig 21 Cylindrical cored bar 22 Pressing jig 23 Cutting jig Wa Width of outer part of reinforcing member Wb Inner part of reinforcing member Width of

Claims (5)

In a fixing device comprising a thin fixing roller having an internal heat source and a pressure roller in pressure contact with the outer peripheral surface of the fixing roller,
A plurality of deformation-preventing ribs are formed on the inner peripheral surface of the fixing roller, and the concave portion of the ring-shaped reinforcing member having a concave portion formed on the outer peripheral surface is joined to at least one of the ribs. A fixing device characterized. In a fixing device comprising a thin fixing roller having an internal heat source and a pressure roller in pressure contact with the outer peripheral surface of the fixing roller,
A plurality of deformation preventing ribs are formed on the inner peripheral surface of the fixing roller, and an outer peripheral surface of a ring-shaped reinforcing member is joined to an inner peripheral surface between at least one of the ribs. Fixing device.   3. The fixing device according to claim 1, wherein the width of the reinforcing member is such that the inner portion is narrower than the outer portion.   The fixing device according to claim 1, wherein a groove is formed in an inner portion of the reinforcing member.   6. The fixing device according to claim 1, wherein a longitudinal elastic coefficient in a material of the reinforcing member is equal to or larger than a longitudinal elastic coefficient in a core metal material of the fixing roller.

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