JP2016038535A - Fixation heater and fixation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixation heater excellent in voltage resistance, heat conductivity and surface smoothness; and a fixation device.SOLUTION: A fixation heater of an embodiment includes: a substrate; a conductor; a resistance heating element; and an overcoat layer. The conductor is formed on the substrate. The resistance heating element is formed on the substrate and electrically connected to the conductor. The sectional porosity of the overcoat layer is 5% or less, the overcoat layer adequately covers the resistance heating element, and the average value of the film thickness covering a central vicinity in the short direction of the resistance heating element is in the range of 30 to 40 μm.SELECTED DRAWING: Figure 3

Description

  Embodiments described herein relate generally to a fixing heater and a fixing device that are used for fixing toner in an image forming apparatus.

  A toner fixing heater used in an image forming apparatus is a plate-like heater in which a resistance heating element and a conductor are provided on a heat-resistant and insulating substrate and covered with an overcoat layer mainly composed of glass. is there. The overcoat layer of the fixing heater is desired to have excellent voltage resistance, thermal conductivity, and surface smoothness.

JP 09-260039 A JP2013-125602A

  Embodiments of the present invention provide a fixing heater and a fixing device that are excellent in voltage resistance, thermal conductivity, and surface smoothness.

The fixing heater of the embodiment includes: a substrate; a conductor formed on the substrate; a resistance heating element formed on the substrate so as to be electrically connected to the conductor; the conductor and the resistance heating element An overcoat layer formed so as to cover the surface.
A cross-sectional porosity of the overcoat layer covering the conductor and the resistance heating element is 5%.
The average thickness of the overcoat layer sufficiently covering the resistance heating element and covering the vicinity of the center in the short direction of the resistance heating element is 30 μm to 40 μm.
The range of m.

According to the embodiment of the present invention, it is possible to provide a fixing heater and a fixing device excellent in voltage resistance, thermal conductivity, and surface smoothness.

It is a schematic diagram for illustrating the fixing heater according to the embodiment. It is a schematic cross section of the AA 'line direction of FIG. 1 which concerns on embodiment. FIG. 3 is a schematic diagram for illustrating the state of holes in an overcoat layer, and is a schematic cross-sectional view of the fixing heater in FIG. 2. It is a figure for illustrating the characteristic of the withstand voltage of the overcoat layer concerning an embodiment. It is a graph for demonstrating the relationship between the film thickness of an overcoat layer, and the temperature rising time of the overcoat layer surface. FIG. 3 is a schematic diagram for illustrating a fixing device that is an example of use of a fixing heater.

The invention according to this embodiment includes: a substrate; a conductor; a resistance heating element; a power feeding electrode;
And an overcoat layer. A cross-sectional porosity of the overcoat layer covering the conductor and the resistance heating element is 5% or less, the overcoat layer sufficiently covers the resistance heating element, and a center in the short direction of the resistance heating element The average value of the film thickness covering the vicinity is in the range of 30 μm to 40 μm.

According to this fixing heater, the thermal conductivity and voltage resistance of the overcoat layer can be improved.

The overcoat layer includes at least one selected from the group consisting of silicon oxide (SiO 2), boron oxide (B 2 O 3), barium oxide (BaO), and zinc oxide (ZnO). It contains a material filler and is made of glass having a lead and bismuth content of less than 0.01% by mass.

  According to this overcoat layer, it is possible to improve the thermal conductivity and the hardness of the glass surface by using a glass material in which the content of lead and bismuth, which are environmentally hazardous substances, is less than 0.01% by mass.

  The overcoat layer is composed of a plurality of layers.

  According to this overcoat layer, the thermal conductivity and the voltage resistance can be improved.

  Further, the ten-point average roughness Rzjis (JIS B 0601: 2001) of the overcoat layer is 0.6 μm or less.

  According to this overcoat layer, practically desirable surface smoothness can be realized in toner fixing properties.

  The fixing device according to the present embodiment includes a fixing heater.

  According to this fixing device, the voltage resistance and the toner fixing property can be improved.

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

  The drawings are schematic or conceptual, and the dimensions and ratios of each part are not necessarily the same as actual ones. In addition, since constituent elements denoted by the same reference numerals in the drawings are the same elements, the description thereof is omitted or simplified as appropriate.

  FIG. 1 is a schematic diagram for illustrating a fixing heater 10 according to an embodiment. FIG. 2 is a cross-sectional view of the fixing heater 10 and is a schematic view for illustrating a cross section in the direction of the A-A ′ line of FIG. 1.

  The fixing heater 10 according to the present embodiment is mounted on a fixing device in the image forming apparatus, and mainly heats a medium such as paper passing therethrough and fixes toner.

The fixing heater 10 according to this embodiment includes a conductor 2 formed on one surface of a substrate 1, a resistance heating element 3, an overcoat layer 6 covering the conductor 2 and the resistance heating element 3, and a power supply electrode 4. , And is formed of a power supply electrode 5.

The board | substrate 1 is formed with the material which has heat resistance and insulation, is a long flat plate shape, and thickness is about 0.5-1.0 mm. For example, it is made of aluminum oxide (Al ₂ O ₃ ), aluminum nitride (AlN), glass ceramic, heat resistant composite material, or the like. The shape of the substrate 1 is not limited to the present embodiment as long as it has a short direction and a longitudinal direction intersecting the short direction.

On one surface of the substrate 1, a conductor 2 is formed in a strip shape. The conductor 2 is made of, for example, a low resistance conductor made of a material containing silver (Ag). The conductor 2 is made of a conductor having a sufficiently low resistance value as compared with the resistance heating element 3. The conductor 2 is formed, for example, by applying a paste-like conductor on the substrate 1, and then drying and firing. “Applying” is to apply a conductor onto the substrate 1, and any means may be used, including screen printing.

The conductor 2 supplies electric power to the resistance heating element 3 from the outside, and is electrically connected to the resistance heating element 3 in the longitudinal direction of the substrate 1. The conductor 21 and the conductor 22 constituting the conductor 2 are formed at predetermined intervals along the longitudinal direction of the substrate 1. A resistance heating element 31 and a resistance heating element 32 are connected to the conductor 21 and the conductor 22, respectively. The conductor 21 is formed along the longitudinal direction of the resistance heating element 31. One end of the conductor 21 is electrically connected to the feeding electrode 4 and the other end is electrically connected to the end of the resistance heating element 31. . The conductor 22 is formed along the longitudinal direction of the resistance heating element 32, and one end is electrically connected to the feeding electrode 5 and the other end is electrically connected to the end of the resistance heating element 32. . The conductor 23 is formed along the short direction of the substrate 1, and electrically connects the other end of the resistance heating element 31 and the other end of the resistance heating element 32.

For example, as shown in FIG. 1, the resistance heating element 3 is formed with a constant width in the short direction of the substrate 1, and is formed at predetermined intervals along the longitudinal direction of the substrate 1. 31 and a resistance heating element 32. On the surface of the substrate 1, for example, a low resistance conductor made of a material containing silver (Ag) or the like is used. The resistance heating element 3 is electrically connected to the conductor 2 and generates heat when energized. The resistance heating element 3 is formed along the longitudinal direction on the substrate 1. The resistance heating element 31 and the resistance heating element 32 constituting the resistance heating element 3 are formed with a constant width in the short direction of the substrate 1 and at a predetermined interval along the longitudinal direction of the substrate 1. Yes. The resistance heating element 3 is not limited to the shape of the present embodiment as long as the fixing property of the toner image can be ensured up to the ends in the width direction of the medium such as paper. For example, the substrate 1 may be tapered in the longitudinal direction. Further, when viewed from the short side direction of the substrate 1, a part of the width may be narrowed or a part of the width may be widened. In addition, the conductor 2 and the resistance heating element 3 may be formed on the substrate 1 first, and the order in which they are formed does not affect the manufacturing method and the usage method of the present invention.

As shown in FIG. 1, the pair of power feeding electrodes 4 and power feeding electrodes 5 are formed at the end portions on the substrate 1. The power feeding electrode 4 and the power feeding electrode 5 are electrically connected to the conductors 21 and 22, respectively, and are electrically connected to the conductors 21 and 22. 1 and 2, the pair of power supply electrodes 4 and the power supply electrode 5 are formed at one end of the substrate 1, but may be formed at the other end of the substrate 1. Alternatively, each may be formed at both ends of the substrate 1.

As shown in FIG. 1, the overcoat layer 6 is formed in, for example, a band shape so as to cover the conductor 21, a part of the conductor 22, the conductor 23, and the resistance heating element 3. The overcoat layer 6 covers the conductor 2 and the resistance heating element 3, thereby preventing the conductor 2 and the resistance heating element 3 from being directly exposed to the atmosphere. Thereby, the conductor 2 and the resistance heating element 3 are prevented from being damaged or broken due to external interference (for example, mechanical, chemical or electrical interference).

Conventional overcoat layers often use glass containing lead. This is because lead has a low softening point, good workability, and excellent electrical insulation. However, the lead component is a hazardous substance and is subject to official regulations. Thus, bismuth-based glass has been studied as an alternative to low-melting glass containing lead. However, since bismuth is collected only in a trace amount as a by-product when producing a large amount of lead, it is very expensive to collect. In addition, it is less toxic than lead but not completely harmless, so it may be subject to official regulations in the future. Considering these reasons, there is a problem in continuing to use bismuth as a material for the overcoat layer in the future. Therefore, the present inventor examined the realization of an overcoat layer excellent in voltage resistance, thermal conductivity, and surface smoothness using a glass material having a lead and bismuth content of less than 0.01% by mass. As a result, it contains at least one selected from the group consisting of at least silicon oxide (SiO 2), boron oxide (B 2 O 3), barium oxide (BaO), and zinc oxide (ZnO), and the content of lead and bismuth is The glass material with an inorganic oxide filler added at less than 0,01 mass% was used.

Since the filler has a higher thermal conductivity than glass, the thermal conductivity of the overcoat layer 6 is improved by adding the filler. Moreover, since the hardness of the overcoat layer 6 can be formed high, the surface of the overcoat layer 6 is hardly damaged, and deterioration of print quality caused by the generation of the scratch can be suppressed.

When adding a filler to glass, in order to improve each characteristic of the overcoat layer 6 mentioned above, the particle size and content of the filler were adjusted. For example, when the particle size of the filler is too large or the content is too large, the filler itself does not dissolve by heat, so that the glass that softens and flows during firing cannot sufficiently entrain the filler. Therefore, the ratio of bubbles mixed in the glass increases, and the voltage resistance of the overcoat layer 6 is reduced. In addition to the fact that the glass surface itself is not formed smoothly due to the deterioration of the softening fluidity of the glass, the filler is finely exposed on the surface of the overcoat layer 6 after firing, and the smoothness of the surface of the overcoat layer 6 is impaired. It is. As a result, the toner fixing property is affected, and the print quality is deteriorated.

In addition to the filler described above, the overvoltage layer 6 has good voltage resistance. For example, when forming the overcoat layer 6 by screen printing, when extruding the glass paste from the squeegee, the air holes 7 are formed by bubbles contained in the glass paste. In addition, the gas generated when the solvent is vaporized during the baking of the glass paste, or the glass that softens and flows at a high temperature reacts with the substrate 1 or the conductor formed on the substrate 1, and the generated gas. The holes 7 are also formed. When the holes 7 remain inside the overcoat layer 6, the portion where the holes 7 exist is substantially the same as the thin film thickness of the overcoat layer 6, so that the withstand voltage is partially reduced. Cause.

The overcoat layer 6 is formed by applying a paste-like glass, then drying, and baking a plurality of times. By forming the glass layer thin per process, the gas contained in the glass layer is easily discharged to the outside during firing. Also, the holes 7 formed in the firing process are filled with paste-like glass applied thereon. As a result, since no pinhole that penetrates the overcoat layer 6 is formed, current leaking through the pinhole can be prevented. Further, the formation of partial holes 7 due to the residual internal gas can suppress the occurrence of a phenomenon that the film thickness is substantially reduced.

  FIG. 3 is a schematic cross-sectional view of the fixing heater 10 in FIG. In general, the porosity is a value that characterizes the proportion of pores in a substance having a porous structure. In the present invention, the area (A) of the cross section of the overcoat layer 6 and the area (B) of all the holes 7 observed in the cross section of the overcoat layer 6 are measured, and the area ratio ((B / A) × 100 [%]) Is defined as the cross-sectional porosity.

The fixing heater 10 as a measurement target is cut along the line AA ′ in FIG. 1, and the observation target portion is cut into a predetermined size. As shown in FIG. 2, an average film thickness portion where the overcoat layer 6 sufficiently covers the resistance heating element 3 and covers the vicinity of the center in the short direction of the resistance heating element 3 is defined as T.

As shown in FIG. 3, the cut-out cross section is embedded in a support such as a resin, and fixed and buffed, and the cross section of the fixing heater 10 is processed to be smooth. Thereafter, the cross section of the overcoat layer 6 in the fixing heater 10 is enlarged to a predetermined size with a laser microscope, and the holes 7 observed on the cross section of the overcoat layer 6 are counted. In addition, the entire area (A) of the cross section of the overcoat layer 6 to be observed and the total area (B) of the vacancies 7 observed on the cross section of the overcoat layer 6 are measured by image analysis software. Is divided by the total cross-sectional area (A) of the overcoat layer 6 to calculate the cross-sectional porosity ((B / A) × 100 [%]).

As shown in FIG. 4, the inventor creates a sample in which the cross-sectional porosity ((B / A) × 100 [%]) of the overcoat layer 6 and the film thickness T of the overcoat layer 6 are changed, The withstand voltage was measured. In the prepared sample, the cross-sectional porosity ((B / A) × 100 [%]) of the overcoat layer 6 is 2%, 5%, 10%, 15%, and the film thickness T of the overcoat layer 6 Are 20 μm, 30 μm, 40 μm, and 55 μm.

The withstand voltage is evaluated by applying an AC voltage for 3 seconds between the resistance heating element 3 and the entire surface of the overcoat layer 6 and measuring the current flowing until 3 seconds have passed. The applied voltage is increased every 0.25 kV, and the voltage at the time when a current of 3 mA or more flows is defined as a withstand voltage value (dielectric breakdown voltage). A withstand voltage value of 1.5 kV or less was regarded as defective, a value obtained by dividing the number of defects by the number of measurement samples was defined as a defect rate, and level determination was performed based on the defect rate as shown in FIG. The defect rate in FIG. 4 is 0%, ○ is greater than 0% and less than 5%, Δ is greater than 5% and less than 30%, and x is greater than 30% and less than 100%. ◎ and ○ are practical levels for the fixing heater 10. As shown in FIG. 4, if the cross-sectional porosity is 10%, the film thickness T needs to be 55 μm or more, but if the cross-sectional porosity is 5% or less, the film thickness T is 55 μm of the conventional product. It was found that even if it was formed to a thickness of 30 μm, it was practical.

In the present embodiment, as a result of suppressing the formation of the holes 7 in the overcoat layer 6, the voltage resistance of the overcoat layer 6 can be improved. Therefore, even if the film thickness T of the overcoat layer 6 is 30 μm, which is thinner than the conventional film thickness of 55 μm, it is possible to maintain practical voltage resistance. Furthermore, the film thickness is desirably in the range of 40 μm to 55 μm from the viewpoint of reliably maintaining the withstand voltage.

FIG. 5 shows the measurement results of the film thickness and the temperature rise time of the overcoat layer 6 having a cross-sectional porosity of 5% or less realized in the present embodiment. For example, when the film thickness T of the overcoat layer 6 is 40 μm, which is thinner than 55 μm of the conventional product, the time to reach the fixing temperature can be shortened to 90% compared with the conventional product having a film thickness of 55 μm. It was.

If the film thickness T of the overcoat layer 6 can be reduced, the thermal conductivity of the overcoat layer 6 is improved, and the time for the heat of the resistance heating element 3 to reach the surface of the overcoat layer 6 is shortened. Can do. As a result, the time (heating time) for the fixing heater 10 to reach the fixing temperature can be shortened and the rise of the fixing heater 10 itself becomes faster, so that the printing speed is improved. In addition, it is possible to reduce the power consumption of the image forming apparatus incorporating the fixing heater.

As shown in FIGS. 4 and 5, by forming the cross-sectional porosity of the overcoat layer 6 to 5% or less, the voltage resistance of the film thickness T could be improved. Thereby,
The film thickness T can be formed in the range of 30 μm to 40 μm, which is thinner than the conventional product, and the thermal conductivity of the overcoat layer 6 can be improved.

  The toner fixability of the fixing device 100 has a great influence on the surface condition as well as the thermal conductivity of the overcoat layer 6. The overcoat layer 6 needs to have a smooth surface in order to ensure slidability and print quality of a heating target such as paper.

The overcoat layer 6 is formed by baking glass having a softening temperature of 660 ° C. to 700 ° C. at 810 ° C. to 850 ° C. In the present embodiment, since the baking is performed at a temperature higher by 100 ° C. or more than usual compared with the softening temperature of the glass, the glass is sufficiently softened and flowed, and the surface of the overcoat layer 6 is densely formed.

In this embodiment, ten-point average roughness Rzjis (JIS B 0601: 2001) is used as a parameter for evaluating the surface state of the overcoat layer 6. Rzjis in the overcoat layer 6 of the fixing heater 10 is desirably less than 1.0 μm in practice.

  In order to evaluate the surface state of the overcoat layer 6, Rzjis was measured at a measurement distance of 2.5 mm and a measurement speed of 0.5 mm / sec using a contact-type ten-point average roughness measuring machine. The measurement was performed not on a portion near the periphery of the overcoat layer 6 but on a normal surface where the overcoat layer 6 sufficiently covered the resistance heating element 3 and did not contain foreign matters or bulges.

The ten-point average roughness Rzjis of the overcoat layer 6 in this embodiment is 0.6 μm or less, and a sufficiently small value can be realized as compared with 1.0 μm which is practically desirable. For this reason, the toner fixability is good, and the overcoat layer 6 has a dense surface, whereby the voltage resistance can be improved.

The overcoat layer 6 in the present embodiment was able to achieve high voltage resistance even when the film thickness T was thin, by improving the cross-sectional porosity. By forming the film thickness T thinly, the thermal conductivity was improved, and since practically sufficient surface smoothness was obtained, the toner fixability was improved.

Next, an embodiment of the fixing device 100 including the fixing heater 10 will be described. FIG. 6 is an explanatory view showing a fixing device 100 as an example of use of the fixing heater 10. The fixing device 100 includes a fixing heater 10, a fixing film 200, and a pressure roller 300. The fixing device 100 is actually built in the image forming apparatus, but the image forming apparatus is omitted.

  The fixing film 200 is a roll film made of a heat resistant sheet such as a polyimide resin. A fixing heater 10 is disposed at the bottom of the fixing film 200.

  The pressure roller 300 is a roller configured to be rotatable by a rotation shaft. A silicone rubber layer is formed on the surface of the roller as a heat-resistant elastic material. The silicone rubber layer is in elastic contact with the fixing heater 10 via the fixing film 200.

  The fixing heater 10 is energized and heat is generated in the heating resistor 3, and the heat heats the fixing film 200 and the pressure roller 300 through the substrate 1. When the sheet 400 having the toner image 500 attached thereto is fed by the rotation of the fixing film 200 and the pressure roller 300, the toner image 500 is heated and melted and softened and melted. Thereafter, on the paper discharge side of the pressure roller 300, the paper 400 is separated from the fixing heater 10, and the toner image 500 'is naturally dissipated to be cooled and solidified to be separated from the fixing device.

  According to the present embodiment, by using the fixing heater 10 having excellent voltage resistance, thermal conductivity, and surface smoothness, it is possible to realize the fixing device 100 having a fast start-up and excellent fixability. it can.

In the present embodiment, the example in which the fixing heater 10 is used for toner fixing of the fixing device 100 has been described. However, the present invention is not limited to this embodiment. For example, it can be used as a heat source for heating or heat retention by being mounted on household electrical products, precision instruments for business use or experiments, equipment for chemical reaction, and the like.

Although the embodiments of the present invention have been described, these embodiments are presented as examples, and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Conductor, 3 ... Resistance heating element, 4, 5 ... Electrode for electric power feeding, 6 ... Overcoat layer, 7 ... Hole, 10 ... Fixing heater

Claims (5)

A substrate;
A conductor formed on the substrate;
A resistance heating element electrically connected to the conductor and formed on the substrate;
On the substrate, the conductor and the resistance heating element are covered, and the cross-sectional porosity is 5%.
In the following, the average value of the film thickness where the overcoat layer sufficiently covers the resistance heating element and covers the vicinity of the center in the short direction of the resistance heating element is in the range of 30 μm to 40 μm. A fixing heater, comprising: an overcoat layer; The overcoat layer includes at least one selected from the group consisting of boron oxide (B2O3), silicon oxide (SiO2), barium oxide (BaO), and zinc oxide (ZnO), and an inorganic oxide filler The fixing heater according to claim 1, wherein the fixing heater is made of glass having a lead and bismuth content of less than 0.01% by mass. The fixing heater according to claim 1, wherein the overcoat layer is formed of a plurality of layers. The fixing heater according to any one of claims 1 to 3, wherein the ten-point average roughness Rzjis of the overcoat layer is 0.6 µm or less. The fixing heater according to any one of claims 1 to 4, which heats a passing medium;
A roller for pressing the medium during heating;
And fixing the toner image attached to the medium by heating and pressurizing the medium.

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