JP6620722B2 - Fixing apparatus and image forming apparatus - Google Patents

Description

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

  For example, a fixing device that includes a fixing belt (heating belt) and a pressure roller, and that fixes the toner image to the medium conveyed with the toner image formed by the fixing belt and the pressure roller is known. (See Patent Documents 1 and 2).

  In the fixing device of Patent Document 1, a polyimide tubular body containing a heat conductive inorganic fine powder, the heat conductive inorganic fine powder is spherical aluminum nitride, and the heat conductive inorganic with respect to 100 parts by weight of the polyimide resin. A heat conductive seamless belt (resin-based fixing belt) having a powder content in the range of 10 to 40 parts by weight is used. Further, in the fixing device of Patent Document 2, a fixing belt (nickel-based) having an endless electrical sheet having a micro Vickers hardness of 450 to 650 made of a nickel-manganese alloy containing 0.05 to 0.6% by weight of manganese as a base. Fixing belt).

JP 2005-17720 A Japanese Patent No. 2706432

  By the way, in the case of the above-mentioned resin-based fixing belt, the thermal conductivity in the surface direction and the thickness direction is low and the fatigue strength is inferior to that of the nickel-based fixing belt. In the case of a nickel-based fixing belt, the thermal conductivity in the surface direction and the thickness direction is higher and the fatigue strength is superior to that of a resin-based fixing belt. However, it is desired that the fixing belt (heating belt) has higher thermal conductivity in the surface direction and thickness direction than the nickel-based fixing belt and has excellent fatigue strength.

  An object of the present invention is to provide a fixing device including a heating belt having high thermal conductivity in the surface direction and thickness direction and excellent fatigue strength.

  A first fixing device according to the present invention has an endless shape, a heating belt that contacts a medium on which a toner image is formed while rotating around an axis while being applied with heat, and heats the medium. A pressure body that rotates and pressurizes the medium with the heating belt, and the heating belt is a single layer made of beryllium copper.

  The second fixing device of the present invention is the first fixing device, wherein the beryllium content in the heating belt is 0.1 wt% or more and 0.9 wt% or less.

  The third fixing device of the present invention is the first or second fixing device, wherein the beryllium copper contained in the heating belt is age-hardened.

  A fourth fixing device of the present invention is any one of the first to third fixing devices, wherein the heating belt includes cobalt and nickel, and cobalt and nickel in the heating belt are formed. A content rate is 3.0 wt% or less.

  An image forming apparatus according to the present invention includes a toner image forming unit that forms a toner image on a medium, and any one of the first to fourth fixing devices formed on the medium by the toner image forming unit. And a fixing device for fixing the toner image on the medium.

  According to the fixing device of the present invention, it is possible to provide a fixing device including a heating belt having high thermal conductivity in the surface direction and thickness direction and excellent fatigue strength.

1 is a perspective view of an image forming apparatus according to a mode for carrying out the present invention (hereinafter referred to as the present embodiment). 1 is a schematic view of an image forming apparatus according to an embodiment as viewed from the front side. FIG. 2 is a schematic view of a fixing device constituting the image forming apparatus of the present embodiment as viewed from the front side. It is a table | surface which shows the result of the 1st evaluation test about a heating belt. It is a table | surface which shows the result of the 2nd evaluation test about a heating belt. It is a table | surface which shows the result of the 3rd evaluation test about a heating belt. It is a table | surface which shows the result of the 4th evaluation test about a heating belt.

≪Overview≫
Hereinafter, the overall configuration of the image forming apparatus 10 (see FIGS. 1 and 2) of the present embodiment, the image forming operation by the image forming apparatus 10, the configuration of the fixing device 60 (see FIG. 3) that is the main part of the present embodiment, and The effect of this embodiment will be described in the order of description.

  In the present specification, the directions indicated by arrows Fr and Rr in the figure are the front and back sides of the apparatus depth direction, respectively, and the directions indicated by arrows R and L are the right and left sides of the apparatus width direction, arrow U and arrow Lo, respectively. The directions shown are the upper side and the lower side of the apparatus height direction, respectively. Further, in this specification, the side of the image forming apparatus 10 viewed from the front side in the apparatus depth direction is described as the front side of the image forming apparatus 10.

<< Overall configuration of image forming apparatus >>
The overall configuration of the image forming apparatus 10 will be described with reference to FIGS. 1 and 2. The image forming apparatus 10 is an electrophotographic apparatus that includes a main body 20, a paper feed cassette 30, a conveying device 40, a toner image forming unit 50, a fixing device 60, and a control unit CU. ing.

  The main body 20 has a function of accommodating a paper feed cassette 30, a transport device 40, a toner image forming unit 50, a fixing device 60, and a control unit CU therein. The main body 20 is a box-shaped exterior. A part of the upper surface of the main body 20 is a discharge tray 22 from which the medium S on which the toner image is fixed (image is formed) is discharged. Note that a lid 24 is provided on the left end surface of the main body 20 as viewed from the front side, and a fixing device 60 described later can be attached to and detached from the main body 20 in a state where the lid 24 is tilted (see FIG. 1). ing.

  The paper feed cassette 30 has a function of accommodating the medium S on which an image is formed in an overlapping manner. The paper feed cassette 30 is disposed on the lower side of the main body 20.

  The transport device 40 has a function of transporting the medium S stored in the paper feed cassette 30 along the transport path P from the paper feed cassette 30 to the discharge tray 22. The conveying device 40 includes a plurality of driven rollers and driving rollers, and a driving source (not shown) that drives the plurality of driving rollers. Here, the direction indicated by the arrow Y in the figure is the transport direction of the medium S.

  The toner image forming unit 50 has a function of forming a toner image on the medium S conveyed by the conveying device 40. The toner image forming unit 50 is disposed in the center of the main body 20 when viewed from the front side. The toner image forming unit 50 includes a photoconductor 51, a charging device 52, an exposure device 53, a developing device 54, and a transfer roller 55.

  The toner image forming unit 50 charges the photoconductor 51 rotating around the axis by the charging device 52, exposes the photoconductor 51 by the exposure device 53 to form a latent image, and forms the latent image as a toner image by the developing device 54. The toner image is developed and the toner image is transferred to the medium S by the transfer roller 55. As described above, the toner image forming unit 50 forms a toner image on the medium S.

  The fixing device 60 has a function of fixing the toner image on the medium S (the medium on which the toner image is formed) on which the toner image is transferred by the toner image forming unit 50. The fixing device 60 is disposed on the left side in the main body 20 as viewed from the front side (on the downstream side in the transport direction of the medium S with respect to the toner image forming unit 50 in the transport path P of the medium S). Since the fixing device 60 is a main part of the present embodiment, a specific configuration of the fixing device 60 will be described later.

  The control unit CU has a function of receiving image data from an external device (not shown) and controlling each element constituting the image forming apparatus 10 based on the image data. Specific functions of the control unit CU will be described in the description of an image forming operation and a supply operation described later.

≪Image formation operation≫
Next, an image forming operation by the image forming apparatus 10 of the present embodiment will be described with reference to FIG.

  First, the control unit CU that has received image data from an external device (not shown) operates the toner image forming unit 50. Then, the charging device 52 charges the photoconductor 51, the exposure device 53 exposes the photoconductor 51 to form a latent image, and the developing device 54 develops the latent image as a toner image. An image is formed.

  In addition, the control unit CU operates the conveying device 40 so that the toner image formed on the photoconductor 51 is transferred around the axis of the photoconductor 51 (the portion where the photoconductor 51 and the transfer roller 55 are in contact). The medium S is sent to the transfer position in accordance with the timing of reaching the position. Then, the transfer roller 55 transfers the toner image formed on the photoconductor 51 to the medium S, and the toner image is formed on the medium S.

  Next, the control unit CU operates the fixing device 60 to fix the toner image transferred to the medium S by the transfer roller 55 on the medium S. Then, the medium S on which the toner image is fixed, that is, the medium S on which the image is formed, is further conveyed downstream in the conveying direction by the conveying device 40 and is discharged to the discharge tray 22 of the main body 20 to perform the image forming operation. finish.

≪Configuration of main part (fixing device) ≫
Next, the configuration of the fixing device 60, which is a main part of the present embodiment, will be described in detail with reference to FIG.

  The fixing device 60 includes a heating belt 61, a pressure roller 62 (an example of a pressure body), a heat source 63, a pressing portion 64, a support member 65, a temperature sensor 66, a housing HG, and a pair of side plates ( (Not shown). The heating belt 61, the pressure roller 62, the heat source 63, the pressing unit 64, the discharge unit 70, and the suction unit 80 are each long, and in a state in which their longitudinal directions are aligned with each other (in the apparatus depth direction). Are positioned on the pair of side plates. The fixing device 60 is long, and is attached to the main body 20 of the image forming apparatus 10 with the longitudinal direction thereof aligned with the apparatus depth direction (see FIG. 1). Note that components other than the housing HG constituting the fixing device 60 are accommodated in the housing HG.

<Heating belt>
The heating belt 61 has a function of heating the toner image (the toner constituting the toner image) formed on the medium S by the toner image forming unit 50 and the medium S. The heating belt 61 is endless. The heating belt 61 is rotated by a pressure roller 62 (described later) while being heated by a heat source 63 (described later). Here, the symbol O in FIG. 3 indicates the axis (rotation center) of the heating belt 61, and the arrow C indicates the rotation direction of the heating belt 61. The heating belt 61 presses the medium S on which the toner image conveyed by the conveying device 40 is formed with a pressure roller 62 at a nip N described later. As a result, the heating belt 61 contacts the medium S on which the toner image is formed while rotating around the axis, heats the medium S, and pressurizes the medium S passing through the nip N with the pressure roller 62. The toner image is fixed on the medium S.

  Flange (not shown) is fitted into both ends of the heating belt 61, and the heating belt 61 is bonded and fixed to each flange. Each flange is rotatably supported by a pair of side plates via a shaft (not shown).

  The heating belt 61 is, for example, a single layer belt made of beryllium copper. Here, the beryllium copper means an alloy obtained by adding at least a beryllium powder to molten copper and then dispersing and solidifying the alloy. Then, the heating belt 61 is a belt composed of an alloy containing copper as a main component and at least beryllium added. Here, the “main component” in the present specification means, for example, that the wt% (weight percentage) of copper in the heating belt 61 is 90 wt% or more. Further, as described above, the heating belt 61 contains beryllium. However, the beryllium content in the heating belt 61 is preferably 0.1 wt% or more and 0.9 wt% or less for the reason described later. Furthermore, it is preferable that the beryllium contained in the heating belt 61 is age-hardened for the reasons described later. Further, as described above, the components other than the main components in the heating belt 61 may be, for example, components containing cobalt and nickel. In this case, it is preferable that the content rate of cobalt and nickel in the heating belt 61 is 3.0 wt% or less for the reason described later. Here, the age hardening treatment in the present specification refers to heat treatment at 315 ° C. for 3 hours in an atmosphere of an inert gas such as nitrogen or argon.

<Pressure roller>
The pressure roller 62 has a function of pressing the toner image (the toner constituting the medium) formed on the medium S by the toner image forming unit 50 and the medium S together with the heating belt 61. The pressure roller 62 is a roller including a long shaft and a coating layer (made of silicon rubber as an example) that covers the outer periphery of the shaft. The pressure roller 62 is disposed on the lower side of the heating belt 61 when viewed from the apparatus depth direction. Further, the lower part of the heating belt 61 in a state of being recessed along the outer periphery of the pressure roller 62 is in contact with the upper part of the pressure roller 62. The above-described nip N means a contact portion between the pressure roller 62 and the heating belt 61 formed by the pressure roller 62 and the heating belt 61.

  A driving source (not shown) is connected to one end of the shaft of the pressure roller 62. The pressure roller 62 is driven by a drive source, rotates around the axis, and rotates the heating belt 61. Here, an arrow B in FIG. 3 indicates the rotation direction of the pressure roller 62.

<Heat source>
The heat source 63 has a function of applying heat for the heating belt 61 to heat the medium S. As an example, the heat source 63 is a rod-shaped halogen lamp. The heat source 63 is disposed above the axis O in the heating belt 61 so as to face the inner periphery of the heating belt 61. The heat source 63 emits light and applies heat to the heating belt 61 when a voltage is applied from a power source (not shown).

<Pressing part>
The pressing portion 64 has a function of pressing a portion forming the nip N in the heating belt 61 against the pressure roller 62. The pressing portion 64 is disposed inside the heating belt 61 and below the axis O when viewed from the apparatus depth direction. The pressing portion 64 includes a pressing member 64A and a sheet member 64B. When viewed from the depth direction of the device, the pressing member 64A is recessed in a curved shape on the lower side. Further, the curved portion of the pressing member 64A is covered with the sheet member 64B. The sheet member 64B is arranged such that the sheet member 64B is sandwiched between the pressing member 64A and the heating belt 61, so that the load due to pressing is reduced compared to the case where the pressing member 64A is in contact with the heating belt 61. It has become. That is, the sheet member 64B has a smaller coefficient of friction than the pressing member 64A.

<Supporting member>
The support member 65 is long. The support member 65 is configured such that a pair of long L-shaped metal plates are alternately opposed to each other, and the cross section is rectangular. The support member 65 is disposed on the upper side of the pressing portion 64 when viewed from the apparatus depth direction. The support member 65 supports the pressing member 64A by screwing as an example.

<Temperature sensor>
The temperature sensor 66 has a function of detecting the temperature of the heating belt 61. The temperature sensor 66 is disposed inside the heating belt 61 and on the left side of the support member 65 when the fixing device 60 is viewed from the front side. Further, the temperature sensor 66 is in contact with the inner periphery of the heating belt 61. In addition, the temperature (data regarding temperature) detected by the temperature sensor 66 is transmitted to the control unit CU at a predetermined cycle.

≪Effect≫
Next, the effect of this embodiment will be described with reference to the tables of FIGS.

<Effect of brother 1>
The first effect is that the heating belt 61 is made of beryllium copper. The first effect will be described while comparing Comparative Examples 1 to 3 and Examples 1 to 5 in the tables of FIGS. 4 and 5.

  In each table, T (s.) Is the time until the temperature of the heating belt 61 reaches 25 (° C.) to 150 (° C.) in the fixing device 60. Δ (° C.) is the difference in temperature of the non-sheet passing portion of the medium S with respect to the temperature of the central portion in the longitudinal direction of the heating belt 61 when 100 sheets of the medium S are passed. P (sheets) is the number of media S on which the heating belt 61 is broken. When P (sheet) did not break at 600 k, the evaluation test was completed at that time. In the evaluation result column, the thermal conductivity in the surface direction is a result derived from Δ (° C.). The thermal conductivity in the thickness direction is a result derived from T (s.). The fatigue strength is a result derived from P (sheets).

In addition, although the evaluation test was performed using the image forming apparatus 10, the main conditions of the evaluation test are as follows.
-Heating belt 61 thickness 35 μm
-Conditions of the heat source 63 for heating the heating belt 61 Applied voltage 100V, input power 800W
・ Pressure roller 62 conditions Rubber elastic layer Silicone rubber 270μm, Hardness JIS-A 20 degrees, Thermal conductivity 0.8W / mK
Toner release layer PFA fluororesin 30μm
・ Fixing temperature 150 ℃
・ Printing speed 40ppm
-Media S printing conditions A4 size vertical feed

  Comparative Examples 1 and 2 show cases where a stainless steel single layer belt and a nickel single layer belt are used as the heating belt 61, respectively. Hereinafter, the following can be understood by comparing the evaluation results of Comparative Examples 1 and 2 with the evaluation results of Comparative Example 2 and Examples 1 to 5 on the basis of the evaluation results of Comparative Examples 1 and 2.

  That is, from the evaluation results of Comparative Examples 1 and 2 and Comparative Example 3, the copper single-layer heating belt 61 containing no beryllium is superior to Comparative Examples 1 and 2 in terms of thermal conductivity. However, Comparative Example 3 is inferior in terms of fatigue strength as compared with Comparative Examples 1 and 2.

  In addition, Examples 1 to 5 are superior to Comparative Examples 1 and 2 in any item of the evaluation results.

  From the above, the heating belts 61 of Examples 1 to 5, which are examples of the present embodiment, have higher thermal conductivity in the surface direction and thickness direction than those of Comparative Examples 1 and 2, and fatigue strength. Is excellent. Accordingly, the fixing device 60 of the present embodiment includes a heating belt 61 having high thermal conductivity in the surface direction and thickness direction and excellent fatigue strength. Therefore, the fixing device 60 and the image forming apparatus 10 of the present embodiment are superior in fixing performance as compared with Comparative Examples 1 and 2.

<Effect of brother 2>
The second effect is that the beryllium content in the heating belt 61 is not less than 0.1 wt% and not more than 0.9 wt%. The second effect will be described while comparing Comparative Example 3 in the table of FIG. 5 and Examples 1-5.

  In the case of Comparative Example 1, the heating belt 61 does not contain beryllium. In contrast, the heating belt 61 of Examples 1 to 5 contains beryllium, and the beryllium content is 0.1 wt% or more and 0.9 wt% or less. And according to the table | surface of FIG. 5, although the comparative example 3 and Examples 1-5 are the single layers based on copper similarly, Examples 1-5 are fatigue strength compared with the comparative example 3. Is excellent in terms of.

  Therefore, at least the beryllium content in the heating belt 61 is 0.1 wt% or more and 0.9 wt% or less, compared with the case where the heating belt 61 does not contain beryllium in terms of fatigue strength. Are better.

<Effect of brother 3>
The third effect is that the beryllium copper constituting the heating belt 61 is age-hardened. The third effect will be described while comparing Examples 2, 4, 6, and 7 summarized in the table of FIG.

  Example 2 and Example 6 have the same beryllium content, although there is a difference in the presence or absence of cobalt and nickel. Further, Example 4 and Example 7 have the same beryllium content although there is a difference in the presence or absence of cobalt and nickel. Comparing each, it can be seen that the age hardening treatment is superior in terms of T (s.) And Δ (° C.).

  Therefore, when the age hardening treatment of beryllium copper is performed, it is superior in terms of thermal conductivity as compared with the case where the age hardening treatment of beryllium copper is not performed.

<Effect of brother 4>
The fourth effect is an effect that the contents of cobalt and nickel in the heating belt 61 are 3.0 wt% or less. The fourth effect will be described while comparing Examples 8 to 12 summarized in the table of FIG.

  Examples 8-12 differ only in the content rate of cobalt and nickel, respectively. According to the table of FIG. 7, the evaluation results equivalent to or higher than those of Comparative Examples 1 and 2 are shown in any of the examples. And all the evaluation results tend to be excellent, so that the content rate of cobalt and nickel is small. Moreover, if the content rate of cobalt and nickel is 3.0 wt% or less, it is superior to Comparative Examples 1 and 2.

  Therefore, when the cobalt and nickel content is 3.0 wt% or less, the thermal conductivity and fatigue strength are greater than those of Comparative Examples 1 and 2 and the case where the cobalt and nickel content is greater than 3.0 wt%. Is excellent in terms of.

  As described above, the present embodiment has been described by taking the present embodiment as an example, but the technical scope of the present invention is not limited to the present embodiment. For example, the following forms are also included in the technical scope of the present invention.

  For example, in the fixing device 60 of this embodiment, the halogen lamp disposed in the heating belt 61 is described as the heat source 63. However, if the heating belt 61 is a belt made of beryllium copper, the configuration of the heat source may be different. For example, the heating belt 61 may be heated by electromagnetic induction by an induction coil (not shown).

10 Image Forming Apparatus 50 Toner Image Forming Unit (Example of Forming Unit)
60 fixing device 61 heating belt 62 pressure roller (an example of a pressure member)
63 Heat source S Medium

Claims (4)

A heating belt that is endless, contacts the medium on which the toner image is formed while rotating around the axis while being heated, and heats the medium;
A pressurizing body that rotates around an axis and pressurizes the medium with the heating belt;
With
The heating belt is a single layer made of beryllium copper ,
The content of beryllium in the heating belt, Ru der least 0.1 wt% 0.9 wt% or less,
Fixing device. The beryllium copper contained in the heating belt is age hardened,
The fixing device according to claim 1 . The heating belt is configured to include cobalt and nickel,
The content of cobalt and nickel in the heating belt is 3.0 wt% or less.
The fixing device according to claim 1 or 2. A toner image forming unit for forming a toner image on a medium;
A fixing device according to any one of claim 1 to 3, the fixing device for fixing a toner image formed on the medium by the toner image forming unit to the medium,
An image forming apparatus.

Images