JP2007017772A - Fixing device and image forming apparatus provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device capable of reducing its power consumption at warm-up time by improving the temperature rise characteristic of a fixing belt. <P>SOLUTION: The fixing device 1 has: a fixing belt 7 which includes a resistor layer generating heat in response to the flow of current and a power feeding section 70 which is formed on the resistor layer and serves as an area to which the current is supplied; a guide member 5 for supporting the fixing belt 7; a pressure roller 4 which is brought into press-contact with the outer surface of the fixing belt 7, so as to form a nip for nipping and conveying a material to be fixed; and a power feeding roller 13 which is brought into press-contact with the fixing belt 7, so as to supply the current to the resistor layer in the power feeding section 70. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device and an image forming apparatus including the same.

  A fixing device mounted on an electrophotographic color printer or a color copying machine is generally a fixing device in which a roller or a fixing belt whose surface is elastic and releasable is heated from the inside by a halogen heater or the like. is there.

  However, in such a fixing device, after the power is turned on, until the roller or the fixing belt reaches a temperature at which the transfer material can be fixed to an object to be fixed such as paper (hereinafter referred to as a fixing temperature). In addition, it takes 1 minute to several minutes. Further, in order to respond to the print request from the user in a short time, it is necessary to maintain the roller and the fixing belt at a high temperature during warm-up, so that the power consumption consumed by the fixing device increases.

  Therefore, while shortening the time until the roller and the fixing belt reach the fixing temperature after turning on the power, the temperature at the time of warming up the roller and the fixing belt is lowered, thereby reducing the power consumption and increasing the temperature. A fixing device with improved characteristics is provided (Patent Document 1). An example of a schematic configuration of such a fixing device is shown in FIG.

  The fixing device shown in FIG. 5 includes a fixing belt 7 having a thin film resistance layer, a power supply roller 100 in contact with the thin film resistance layer, a pressure roller 400 that is disposed to face the power supply roller 100 and is rotatably provided. A driving roller 110 for driving the fixing belt 700, and a tension roller 120 for applying tension to the fixing belt 700.

FIG. 6 is a side view showing a schematic configuration of the power supply roller 100 in the fixing device shown in FIG. The power supply roller 100 includes an electrode member 300 disposed at both ends of the power supply roller 100 and a resin roller 310 having high heat resistance and high electrical insulation. In the fixing device having the configuration shown in FIGS. 5 and 6, the inner surface of the fixing belt 700 is formed by supplying power to the thin film resistance layer by the power supply roller 100 so that the thermal response of the fixing belt 700 is good. Directly heated.
JP-A-7-64416

  However, the conventional fixing device described above has a problem that heat for heating the fixing belt is greatly deprived by a member that contacts the fixing belt, so that the effect of improving the heat responsiveness of the fixing belt is not sufficiently exhibited. It was. That is, in the above-described conventional fixing device, the contact area between the fixing belt 7 and the power supply roller 100 and the heat capacity of the power supply roller 100 are large. For this reason, when the fixing belt 700 is heated, heat that heats the fixing belt 700 is greatly deprived by the power supply roller 100, and the temperature increase rate of the fixing belt 700 becomes slow.

  SUMMARY An advantage of some aspects of the invention is that it provides a fixing device capable of improving the temperature rise characteristics of a fixing belt and reducing the power consumption of the fixing device during warm-up. And

  The above object of the present invention is achieved by the following means.

  (1) A fixing belt that includes a resistor layer that generates heat when current flows, and in which a power feeding unit that is a region to which current is supplied to the resistor layer is formed, and a guide member that supports the fixing belt And a pressure member pressed against the outer surface of the fixing belt to form a nip for sandwiching and transporting an object to be fixed, and a current supply to the resistor layer in the power feeding unit, And a power supply unit that is pressed against the fixing belt.

  (2) The power feeding unit is formed at both ends of the fixing belt that does not contribute to image formation, the guide member is provided to support both ends of the fixing belt, and the power feeding unit includes the fixing belt. The fixing device according to (1), wherein the fixing device is pressed against both ends of the fixing device.

  (3) The fixing device according to (1) or (2), wherein the power supply unit is arranged to face the pressure member via the fixing belt.

  (4) The fixing device according to (1) or (2), wherein the power supply unit is arranged to face the guide member with the fixing belt interposed therebetween.

  (5) In order to prevent buckling of the fixing belt, the fixing belt further includes buckling prevention means disposed at the center of the fixing belt so as to face the pressure member via the fixing belt. The fixing device according to any one of (1) to (4).

  (6) An image forming apparatus comprising the fixing device of (1) to (5).

  According to the present invention, the thermal responsiveness of the fixing belt is improved by minimizing the contact area between the fixing belt and the member in contact with the fixing belt and the heat capacity of the member in contact with the fixing belt.

  As a result, the temperature rise characteristic of the fixing belt is improved, and the power consumption of the fixing device during warm-up can be reduced.

  The first embodiment of the present invention will be described below.

  FIG. 1 is a perspective view showing a schematic configuration of a fixing device 1 according to the first embodiment of the present invention.

  The fixing device 1 includes a resistor layer 43 (see FIG. 3 to be described later) that generates heat as a current flows, and a fixing belt 7 in which a power feeding unit 70 that is a region where current is supplied to the resistor layer 43 is formed. And a pressure roller 4 (pressure member) pressed against the outer surface of the fixing belt 7 to form a nip for holding and conveying the object to be fixed, and a guide 5A (guide member) for supporting the fixing belt 7. And a power feeding roller 13 </ b> A (power feeding means) that is pressed against the fixing belt 7 in order to supply a current to the resistor layer 43 in the power feeding unit 70. The above nip means an area sandwiched between the fixing belt 7 and the pressure roller 4.

  The guide 5 </ b> A is disposed inside the fixing belt 7 and is provided so as to support both ends of the fixing belt 7.

  In addition, the power supply unit 70 is also formed at both ends of the fixing belt 7, and the power supply roller 13 </ b> A can supply a current to the power supply unit 70 at each end of the fixing belt 7. Two are provided inside each of the belts and are pressed against the fixing belt 7. By being provided in this way, the power supply roller 13 </ b> A is disposed so as to face the pressure roller 4 with the fixing belt 7 interposed therebetween.

  Since the fixing belt 7 is pressed toward the pressure roller 4 by the power supply roller 13A, the fixing belt 7 has a wavy cross section at the nip. As a result, the rigidity of the fixing belt 7 in the longitudinal direction is increased, and buckling of the fixing belt 7 that can be caused by the pressure received from the pressure roller 4 is prevented.

  FIG. 2 is a perspective view illustrating a schematic configuration of the fixing device when a large nip pressure is required in the first embodiment.

  In the fixing device of the present embodiment, when a large nip pressure is required, the fixing device further includes a buckling prevention roller 14 (buckling prevention means) for preventing buckling of the fixing belt from the configuration shown in FIG. May be provided. When the buckling prevention roller 14 is disposed at the center of the fixing belt 7, the above-described buckling prevention effect is most exerted.

  FIG. 3 is a cross-sectional view of the fixing belt 7 in the first embodiment. In FIG. 3, the upper side shows the outside of the fixing belt 7 (that is, the lower side shows the inside of the fixing belt 7).

  The fixing belt 7 includes a release layer 41 for promoting separation of the transfer material from the fixing belt 7 in order from the outside to the inside, and an elastic layer provided when an image with high glossiness is required to be formed. 42, the resistor layer 43 described above, a base material layer 44 formed of an insulating member, and a reinforcing layer 45 for reinforcing the rigidity in the longitudinal direction of the fixing belt.

  The release layer 41 is made of, for example, a fluorine film having a thickness of about 5 μm.

  The resistor layer 43 is made of, for example, a thin film resistor obtained by depositing SUS by about 7 μm on a substrate made of polyimide.

  The reinforcing layer 45 is formed using, for example, an iron-based material having a small heat capacity and high rigidity. This prevents a reduction in the rigidity of the fixing belt 7 that may occur when the fixing belt 7 has the above-described wavy cross-sectional shape.

  FIG. 3 shows a cross section of the fixing belt 7 in a region other than the power supply unit 70, and the base material layer 44 and the reinforcing layer 45 are omitted from the power supply unit 70. Thereby, the power supply roller 13 </ b> A can contact the resistor layer 43 in the power supply unit 70 and supply current to the resistor layer 43.

  Next, the operation of the fixing device 1 will be described.

  When a current is supplied to the resistor layer 43 by the power supply roller 13A in the power supply unit 70, the resistor layer 43 generates heat, and the temperature of the fixing belt 7 rises.

  The fixing material having the transfer material attached to the surface is conveyed through the center of the nip, which is the region between the fixing belt 7 and the pressure roller 4 where the temperature has increased. During this conveyance, the fixing material is pressed by the fixing belt 7 and the pressure roller 4 and heated by the fixing belt 7 whose temperature has been increased, so that the transfer material adhered to the surface of the fixing material. Is fixed to the fixing material. At the time of fixing, the fixing belt 7 is pressed by the pressure roller 4. At this time, the fixing belt 7 is supported by the power supply roller 13 </ b> A together with the guide 5 </ b> A, thereby preventing the fixing belt 7 from being deformed.

  Here, as described above, the fixing material is conveyed through the central portion of the nip. From this, it can be said that the central portion of the fixing belt 7 is a region contributing to image formation, and the end portion of the fixing belt 7 is a region not contributing to image formation. In view of this, the guide 5A, the power feeding unit 70, and the power feeding roller 13A are provided at the end of the fixing belt 7 (that is, a region that does not contribute to image formation) so that they do not interfere with image formation. Yes.

  As described above, in the fixing device of this embodiment, the power supply roller that supplies current to the fixing belt and also functions as a backup unit that supports the fixing belt and prevents deformation of the fixing belt from the pressing force of the pressure roller. Is provided. For this reason, when forming the nip, it is not necessary to provide a pad having a large contact area with the fixing belt, a backup roller, or the like at a position facing the pressure roller. As a result, the contact area between the fixing belt and the member in contact with the fixing belt and the heat capacity of the member in contact with the fixing belt can be minimized. For example, in the conventional fixing device shown in FIG. 6, since the power supply roller 100 having a large contact area with the fixing belt is provided as the backup unit, the heat for heating the fixing belt 700 is supplied to the power supply roller 100. Many are robbed. On the other hand, in the fixing device according to the present embodiment, it is not necessary to provide a power supply roller as shown in FIG. 6 by applying a power supply roller as the backup means. As a result, as compared with the conventional fixing device, the contact area between the fixing belt and the member in contact with the fixing belt and the heat capacity of the member in contact with the fixing belt can be minimized.

  From the above, in the fixing device according to the present embodiment, the heat responsiveness of the fixing belt is improved, the temperature rising characteristic of the fixing belt is improved, and the power consumption of the fixing device during warm-up can be reduced.

  Next, a second embodiment of the present invention will be described.

  FIG. 4 is a perspective view showing a schematic configuration of the fixing device 2 according to the second embodiment of the present invention. In the following description, components that are the same as those in the first embodiment are denoted by the same reference numerals as those described in the description of the first embodiment. In the fixing device according to the second embodiment, the basic configuration and operation are the same as those of the fixing device 1 according to the first embodiment, and thus the description thereof is omitted.

  In the present embodiment, the wavy guide 5 </ b> B is disposed inside the fixing belt 7 at both ends of the fixing belt 7 so as to face the pressure roller 4 via the fixing belt 7 in order to support the fixing belt 7. Is done.

  Thereby, also in this embodiment, the fixing belt 7 has a wavy cross section at the nip. As a result, the rigidity in the longitudinal direction of the fixing belt 7 is increased in the same manner as in the first embodiment, and buckling of the fixing belt 7 that can be caused by the pressure received from the pressure roller 4 is prevented.

  In addition, two power supply rollers 13 </ b> B are arranged outside the fixing belt 7 at each of both ends of the fixing belt 7 so as to face the guide 5 </ b> B through the fixing belt 7.

  In the fixing device according to this embodiment, the power supply roller 13B prevents the fixing belt 7 from being deformed so as to swell in a direction away from the guide 5B due to the pressing force of the pressure roller 4. For this reason, also in the fixing device in the present embodiment, the power supply roller 13B functions as the backup unit described above, and the same effects as those described in the first embodiment can be exhibited.

  Note that one or more power supply rollers 13B may be provided at each of both ends of the fixing belt 7 as long as the power supply rollers 13B function as the backup unit and can supply a sufficient current to the resistor layer.

  Further, in the fixing device of the present embodiment, when a large nip pressure is required, the fixing device 2 includes a buckling prevention roller (buckling) for preventing buckling as in the fixing device 1 shown in FIG. Prevention means) may be provided. Similarly to the above, when this buckling prevention roller is disposed at the center portion of the fixing belt 7, the effect of preventing buckling is maximized.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims.

  For example, the pressure member for pressing the fixing belt is not limited to the above-described pressure roller, and may be a belt, a pad, or the like.

  The image forming apparatus provided with the fixing device of the present invention may be any one of a monochrome / color copying machine, a printer, a FAX, and a complex machine thereof.

1 is a perspective view showing a schematic configuration of a fixing device according to a first embodiment of the present invention. FIG. 3 is a perspective view illustrating a schematic configuration of a fixing device when a large nip pressure is required in the first embodiment. FIG. 3 is a cross-sectional view of the fixing belt 7 in the first embodiment. FIG. 6 is a perspective view illustrating a schematic configuration of a fixing device according to a second embodiment of the present invention. FIG. 10 is a cross-sectional view illustrating a schematic configuration of a conventional fixing device. FIG. 6 is a side view illustrating a schematic configuration of a power supply roller 10 in the fixing device illustrated in FIG. 5.

Explanation of symbols

1, 2 fixing device,
4 Pressure roller (pressure member),
5A, 5B guide (guide member),
7 Fusing belt,
13A, 13B feeding roller (feeding means),
14 Buckling prevention rollers (buckling prevention means),
43 resistor layer,
70 Power supply unit.

Claims (6)

A fixing belt that includes a resistor layer that generates heat as current flows, and that forms a power feeding unit that is a region where current is supplied to the resistor layer;
A guide member for supporting the fixing belt;
A pressure member pressed against the outer surface of the fixing belt to form a nip for sandwiching and transporting an object to be fixed;
In order to supply a current to the resistor layer in the power supply unit, a power supply unit that is pressed against the fixing belt;
A fixing device. The power feeding unit is formed at both ends of the fixing belt that does not contribute to image formation,
The guide member is provided to support both end portions of the fixing belt,
The fixing device according to claim 1, wherein the power feeding unit is in pressure contact with both ends of the fixing belt.   The fixing device according to claim 1, wherein the power feeding unit is disposed to face the pressure member via the fixing belt.   The fixing device according to claim 1, wherein the power feeding unit is disposed to face the guide member with the fixing belt interposed therebetween.   In order to prevent buckling of the fixing belt, the fixing belt further comprises buckling prevention means disposed at the center of the fixing belt so as to face the pressure member through the fixing belt. The fixing device according to claim 1.   An image forming apparatus comprising the fixing device according to claim 1.

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