JPH06338380A - Heater and manufacture thereof - Google Patents

Abstract

PURPOSE:To improve the thermal efficiency of a heater section and reduce the power consumption by using a diamond film formed by the vapor phase synthesis method as the protective layer of a heater. CONSTITUTION:A heater 1 is fixed and supported by a heat support section 9 via an adiabatic heater holder 8. A film 10 is rotated or traveled while being slid on the heater 1 face in close contact with the heater 1 face in the direction of an arrow at the prescribed speed by a driving member. The heater 1 is heated to the prescribed temperature by the excitation to the excitation heating resistor 3 of the heater 1. A protective layer made of a polycrystalline diamond film formed by the vapor phase synthesis method is used as the protective layer 6 of the resistor 3. The heat conductivity of the protective layer 6 is increased, and the improvement of the thermal efficiency of the heater 1 section and the reduction of the power consumption can be realized.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heater used in an image forming apparatus such as a copying machine or a laser beam printer, and more particularly to a heater used for heat fixing an unfixed image.

[0002]

2. Description of the Related Art In recent years, Japanese Patent Laid-Open No. 63-313182 proposes a heating device using a fixed heater and a thin film that slides on the heater.

Such a heater will be described with reference to FIGS. 1 and 2 showing the heater according to the present invention. The heater 1 is an elongated substrate 2 having electrical insulation, heat resistance and low heat capacity.
And a current-carrying heating element 3 formed in the shape of a straight strip along the length of the board in the center of the board 2 on the one surface side (front surface side) in the board width direction, and conducting current to both ends of the current-carrying heating resistor. Electrode terminals (connection terminals) 4 and 5 formed on the surface of the substrate, an electrically insulating protective layer 6 such as glass as a heater surface protective layer that covers the surface of the substrate 2 on which the electric heating resistors are formed, and the substrate 2 It has a temperature detecting element 7 such as a thermistor provided on the side (back side). The substrate 2 has, for example, a width of 10 mm
Al ₂ O ₃ , AlN, S with a thickness of 1 mm and a length of 240 mm
It is a ceramic plate such as iC. The energization heating resistor 3 is
For example, Ag / Pd (silver-palladium alloy), RuO ₂ , which has a thickness of 10 μm and a width of 1 mm, is applied by screen printing or the like.
This is a pattern layer formed by firing Ta ₂ N or the like in the atmosphere.
The electrode terminals (connection terminals) 4 and 5 are pattern layers formed by normally baking 10 μm thick Ag coated by screen printing or the like in the air. The electrodes 4 and 5 are usually connectors (not shown). Connect the electric wire via and supply power.

In the heater 1, in order to control and control the temperature of the fixing surface, in the cross section of the apparatus, the current-carrying heat-generating resistor 3 is provided in the central portion of the width region of the fixing nip portion 15 (joining nip portion, pressure portion). The structure is located in. The insulating protective layer 6 side of the heater 1 is the film contact sliding surface side. A voltage is applied to the heater 1 from an AC power source 12 between the electrode terminals 4 and 5 of the energization heating resistor 3, and the energization heating resistor 3 generates heat to raise the temperature. The temperature of the heater 1 is detected by the temperature detection element 7 on the back surface of the substrate, and the detected information is used as the energization control circuit 1
3 is fed back to control the energization from the AC power supply 12 to the energization heating resistor 3, and the temperature of the heater 1 is controlled to a predetermined temperature. The temperature detecting element 7 of the heater 1 has a fixing surface having the best thermal response, that is, a substrate rear surface partial position (corresponding to a position directly below the energization heating resistor 3) corresponding to the formation position of the energization heating resistor 3 on the heater substrate surface side. It is arranged at the substrate rear side partial position).

[0005]

In order to fix an unfixed image, the heat of the heater is transferred through the insulating protective layer on the heater and the film contact sliding surface to fix the image. However, the abrasion of the film becomes severe when the contact sliding distance reaches about 60 km due to abrasion at the time of sliding contact between the insulating protective layer and the film. The abrasion powder generated at this time is nonuniformly attached to the roller that drives the film, so that the driving speed of the film becomes irregular, and as a result, the unfixed image is unfixed. The glassy layer used for the insulating protective film is formed by printing and baking low softening point glass.
It is considered that the film is worn due to the difference in surface shape (difference in friction coefficient) and the difference in hardness between the glassy layer and the film. Therefore, although a filler is mixed in the heat-resistant polyimide film or a Teflon coating or the like is applied to reduce the friction coefficient to prevent the film from being rubbed, the sufficient effect has not been obtained yet.

Further, since the protective layer is made of a material such as glass having a small thermal conductivity, the heat of the heater is not efficiently supplied to the unfixed image, and an excessive amount of heat is required for fixing. When the energization current is increased, the spring material (generally phosphor bronze) forming the connector as shown in FIG. 3 deteriorates due to high temperature creep, causing a drop in contact pressure, an increase in connection resistance value, and further thermal runaway. As a result, the reliability of the connection part and the device is deteriorated. For this reason, there is a demand for a heat fixing device having a longer life (long contact sliding distance), which cannot cope with the increase in fixing speed and the increase in fixing volume.

[0007]

According to the present invention, by using a diamond film having a high electrical insulation property, a high thermal conductivity, a high hardness and a low friction coefficient, which is formed by a vapor phase synthesis method as a protective layer of a heater, This is a solution to the above problem.

The present invention will be described in detail below. The diamond crystal according to the present invention has a thermal conductivity of 600 to 2
100 W / m · k, electric resistance (volume resistivity) 10 ¹⁰ -1
It has physical properties represented by 0 ¹⁶ Ωcm and a hardness of 10000 kgf / mm ² .

In the present invention, the substrate for forming the diamond film is preferably a material suitable for forming a diamond crystal and at the same time capable of mechanical polishing and etching. Such materials include Si, Ta, Mo, W, SiC, WC, SiO ₂ ,
Examples include Al ₂ O ₃ and Si ₃ N ₄ .

The vapor phase synthesis method of diamond crystals used in the present invention is a hot filament CVD method, a microwave plasma CVD method, a direct current plasma CVD method, a high frequency plasma CV.
D method, magnetic field microwave plasma CVD method, combustion flame method and the like can be mentioned. The raw material gas used at this time is a hydrocarbon such as methane, ethane, propane, ethylene, benzene, and acetylene as a carbon source; a halogenated hydrocarbon such as methylene chloride, carbon tetrachloride, chloroform, and trichloroethane; methyl alcohol, ethyl alcohol, etc. _{alcohols; (CH 3) 2 CO,} (C 6 H 5) 2 ketone such as CO; CO, N ₂ gas, such as CO _2, and these _{gases, H 2, O 2, H} 2 O, A mixture of gases such as Ar may be used.

The diamond crystal synthesis conditions are, for example,
In the microwave plasma CVD method using a hydrogen-methane system as a source gas, the methane gas concentration is usually 0.1 to 1.0.
%, Substrate temperature 600 ° C. to 900 ° C., gas pressure 1.33
~ 26.6kPa, total gas flow rate 100 ~ 1000ml
/ Min. And The conditions for forming diamond crystals differ depending on the synthesis method.

The diamond crystal described in the present invention can be confirmed as a diamond crystal by an analysis method such as X-ray diffraction, electron beam diffraction or Raman spectroscopy. For example, in Raman spectroscopy, as shown in FIG.
Has a sharp diamond peak near m ^-1
a broad peak due to carbonaceous non-diamond components in the vicinity cm ^-1 and 1550 cm ^-1 are those slightly with. The thermal conductivity of a diamond crystal largely depends on the crystallinity of diamond, and the crystal having a better crystallinity and less impurities has a better thermal conductivity. (It becomes larger.) Therefore, in the Raman spectrum, 1360 cm ^-1 and 15
It is preferable that a broad peak around 50 cm ^-1 is not observed. The ratio of the presence of diamond and amorphous carbon is determined by Raman spectroscopic analysis of the amorphous carbon peak (1550 cm).
Broad peak around ^-1 ) and diamond peak (1
In terms of intensity ratio (I ₁₅₅₀ / I ₁₃₃₃ ) with respect to 333 cm ⁻¹ , it is ideal that 0 ≦ I ₁₅₅₀ / I ₁₃₃₃ ≦ 1. When I ₁₅₅₀ / I ₁₃₃₃ > 1, the crystallinity of diamond deteriorates and the thermal conductivity decreases. Furthermore, the crystallinity of diamond has a large correlation with the type and concentration of the raw material gas under the film forming conditions. For example, in a methane-hydrogen system, the crystallinity improves as the methane concentration decreases, and the thermal conductivity also increases accordingly. Alternatively, in the methane-hydrogen-oxygen system, the atomic ratio of carbon and oxygen in the raw material gas is O / C = 0.
By setting it to 8, a diamond film with good crystallinity can be obtained. It should be noted that improving the crystallinity of diamond means satisfying the above-mentioned physical properties of diamond, and at the same time, in addition to high thermal conductivity, properties such as high insulation are also realized.

The thickness of the diamond layer is a thickness that can ensure a sufficient dielectric strength under the conditions of use of the heater and a mechanical strength capable of protecting the heater from the pressing force at the time of fixing, and is in the range of several μm to several 1000 μm. I wish I had it. Preferably, it is several tens of μm to several hundreds of μm.

After forming the diamond film or layer on the above-mentioned substrate, a heating resistor serving as a heater is formed by a PVD method such as a sputtering method, the resistance value is measured, and trimming is performed if necessary. Similarly, Au, Ag, and Cu are used to form electrode terminals by a sputtering method. Next, after a ceramic paste (adhesive) is formed on the diamond film, the heating resistor, and the electrode terminals by screen printing or the like, a ceramic insulating substrate is attached and baked to bond them. The method of forming the heating resistor and the electrode terminal is not limited to the PVD method such as the sputtering method, the vacuum deposition method, the ion plating method, and the like.
You may use methods, such as CVD method, plating, and screen printing. After that, the diamond film forming substrate is removed by mechanical polishing or chemical etching. here,
The surface of the diamond film reflects polycrystallinity, and the better the crystallinity, the higher the surface roughness. A few hundred
It is 0Å to several μm. However, since the surface roughness of the diamond film after removing the substrate is equal to the surface roughness of the substrate used for forming the diamond film, the surface roughness of the overcoat layer is Rmax. Can be less than a few 100Å. Further, an electrode tab is attached to the electrode terminal by brazing, a wire is pressed against the electrode tab, and the heater is bonded to the heater holder to complete the heater of the present invention.

In the present invention, by using the diamond film formed by the vapor phase synthesis method as the protective layer of the heater, the thermal efficiency of the heater portion is improved, the power consumption is reduced, and the abrasion resistance and the sliding property of the protective layer are improved. It realizes a heater with excellent movability.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below with reference to the drawings.

<Embodiment 1> FIG. 5 is a partially enlarged sectional view of a heating and fixing apparatus using a heater according to an embodiment of the present invention.
The heater 1 is fixedly supported by a heater supporting portion 9 via a heat insulating heater holder 8. Reference numeral 10 denotes an endless belt-shaped or long web-shaped heat-resistant film such as polyimide having a thickness of about 40 μm, and 11 denotes a rotary pressure roller as a pressure member for pressing the film against the heater 1. The film 10 is rotated or moved while sliding on the heater 1 surface in a state of being in close contact with the heater 1 surface in a direction of an arrow at a predetermined speed by a driving member (not shown) or a rotational force of the pressure roller 11. To do. The heater 1 is heated to a predetermined temperature by energizing the energization heating resistor 3 of the heater 1, and the recording material 16 is used as a material to be heated in the fixing nip portion 15 in a state where the film 10 is moved and driven. The film 10
The recording material 16 becomes the film 10 by introducing the recording material 16 on the surface side.
The recording material 16 is passed through the fixing nip portion 15 together with the film 10 while closely adhering to the surface, and heat energy is applied to the recording material 16 from the heater 1 via the film 10 in the course of the movement, and the unfixed toner image 17 on the recording material 16 is applied. Is melted and fixed by heating.

FIG. 6 is a schematic sectional view showing the first embodiment. In the figure, 1 is a heater, 2 is a ceramic substrate, and 3 is A.
A heating resistor made of g / Pd, 4 an electrode terminal made of Cu, 5 a substrate such as Si for forming a diamond film, 6 a protective layer made of a polycrystalline diamond film, 8 a heater holder, 12 an electrode tab , 13 are brazing materials made of AuSi, and 14 are wires.

In this embodiment, first, a polycrystalline diamond film 6 was formed on the diamond film forming Si substrate 5 ((a) of FIG. 6). The portion of the Si substrate where the diamond film is not formed was previously masked with a resist. This substrate was placed in an alcohol solution in which diamond abrasive grains of 15 to 30 μm were dispersed, and a scratch treatment was performed using an ultrasonic oscillator, and then the resist on the mask was removed. This substrate was placed in the apparatus shown in FIG. 7 to form a diamond film. FIG. 7 is a schematic view of a hot filament CVD apparatus for forming diamond. In the figure, 20 is a quartz reaction tube, 21 is an electric furnace, 22 is a tantalum filament, 23 is a substrate, and 24 is a raw material gas inlet port, which are not shown. It is connected to the gas cylinder, gas flow controller, and valve. Two
A gas exhaust port 5 is connected to a mechanical booster pump, a rotary pump, and a valve (not shown).
The substrate was installed in the apparatus shown in FIG. 7, and after exhausting it with a vacuum pump (not shown), 1 ml / mi of methane was supplied from a gas cylinder (not shown)
n. , Hydrogen 999 ml / min. At a flow rate of 1, the pressure inside the reaction tube was adjusted to 6.00 kPa by a pressure adjusting valve (not shown), and the electric furnace 21 was used to heat the inside of the reaction tube to 900 ° C. and the filament to 2100 ° C. To form a diamond film. The synthesis time at this time is 2
At 0 hours, the resulting diamond film had a thickness of 40 μm. Scanning electron microscope (S
According to EM observation, it was a polycrystalline film with a clear self-shaped surface. According to Raman spectroscopic analysis, a sharp peak of diamond is observed near 1333 cm ⁻¹ , and the intensity ratio between the amorphous carbon peak and the diamond peak is I ₁₅₅₀ / I _1333.
It was ≦ 0.1. Further, the thermal conductivity of the diamond film produced under the same conditions was measured by the radiative cooling method.
It was 0 W / m · k.

On this diamond film, as the heating resistor 3, Ti of 200 Å and Au of 10 μm were sequentially formed by the sputtering method. Measure the resistance value of the heating resistor,
Trimming was performed as necessary to obtain a desired resistance value. Subsequently, Cu was sputtered to form the electrode terminal portion 4 (above, (a) of FIG. 6). Then, an alumina paste (adhesive) is applied to the ceramic substrate 2 made of alumina.
Were bonded and fired to be integrated ((b) of FIG. 6). At this stage, the Si substrate is mechanically polished and Si etchant (for example, HF / HNO ₃ / CH ₃ COO) is used.
H) was used to remove (FIG. 6 (c)).

In the heater substrate or insulating substrate from which the Si substrate has been removed, the brazing material 13 made of AuSi is used to bring the electrode terminals 4, the electrode tabs 12 made of a copper alloy and the ceramic substrate 2 to a melting point of the brazing material of 370 ° C. or higher. It heated and brazed and alloyed ((d) of FIG. 6). The wire 14 is pressed against the attached electrode tab 12 ((e) of FIG. 6),
The heater 1 was bonded to the heater holder 8 ((f) in FIG. 6). By flash-plating Au on the surface of the electrode terminal portion 4 when the heater 1 is manufactured, the wettability of the brazing material can be improved during brazing, and stable connection reliability can be obtained. As the electrode tab material, a metal such as Kovar, 42 alloy, phosphor bronze or the like can be used in addition to the copper alloy. The brazing material preferably has a melting point of 250 ° C. or higher, and AuGe, AuSu or the like can be used in addition to AuSi. Further, by forming Au, Ni, Au / Ni by flash plating or the like for the purpose of preventing surface oxidation before brazing on the surface of the Cu electrode terminal and providing chemical resistance when removing the Si substrate, more stable The brazing can be realized. At this time, the purpose of forming the Ni layer is to prevent excessive diffusion of Cu in the brazing material.

The heater 1 manufactured as described above is
The heat generated by energization can be efficiently supplied to the recording material side, and stable heater performance can be realized without causing thermal deterioration of heater constituent members.

<Embodiment 2> In the same manner as in Embodiment 1, Si
A polycrystalline diamond film was formed on the substrate. A schematic view of the microwave plasma CVD apparatus used for diamond formation is shown in FIG. In the figure, 26 is a quartz reaction tube, 27 is a Si substrate, 28 is a source gas introduction system, 29 is a microwave power source, 3
Reference numeral 0 is a microwave waveguide, and 31 is a vacuum exhaust system.

S that has been scratched with diamond grains
After the i substrate was put into the apparatus shown in FIG. 8 and exhausted by the vacuum exhaust system 31, 25 ml / mi of carbon monoxide was introduced from the source gas introduction system.
n. , Hydrogen 375 ml / min. It is introduced into the quartz reaction tube at the flow rate of
Adjusted to a and microwave output 4 from microwave power supply 29
A diamond film was synthesized at kW and a substrate temperature of 900 ° C.
At this time, the synthesis time was 10 hours and the film thickness was 150 μm. The diamond film synthesized in the same manner is SEM
As a result of observation, the polycrystalline film had a clear self-shaped surface, and the thermal conductivity measured by the radiative cooling method was 1500 W / m · k.

On this diamond film, a paste made of Ag / Pd was applied at a predetermined position by screen printing so that the heating resistor 3 would be formed. The resistance value of the heating resistor was measured and trimming was performed as necessary to obtain a desired resistance value. Next, the Cu paste was applied by screen printing to form the electrode terminal portion 4. Thereafter, an alumina-based paste (adhesive) was applied, and the alumina ceramics substrate 2 was attached and fired to be integrated. A heater was produced by removing the Si substrate in the same manner as in Example 1. Furthermore, after connecting an electrode tab and a wire to the electrode terminal portion, they were adhered to the heater holder portion to complete the heater. As a result of thermal fixing of the recording material using this heater in the same manner as in Example 1, stable fixing similar to that in Example 1 could be realized.

[0026]

As described above, according to the present invention, in the heat fixing heater used in the image forming apparatus by heat fixing, the protective layer of the heater is a diamond film formed by the vapor phase synthesis method. Increase the thermal conductivity of the protective layer,
It is possible to improve the thermal efficiency of the heater section and reduce the power consumption. At the same time, abrasion resistance and slidability as a protective layer can be improved, and a heater with extremely high reliability can be provided. As a result, it becomes possible to supply a large current in a stable manner, increasing the fixing speed,
The fixing size can be increased.

[Brief description of drawings]

FIG. 1 is a plan view of a heating resistor side of a heater according to the present invention.

FIG. 2 is a plan view of the back side of the heater according to the present invention.

FIG. 3 is a sectional view of a heater according to the present invention.

FIG. 4 is measurement data of Raman spectrum of diamond crystal according to the present invention.

FIG. 5 is a sectional view of a fixing device using a heater according to an embodiment of the present invention.

FIG. 6 is a partial sectional view of a heater according to an embodiment of the present invention.

FIG. 7 is a schematic diagram of a hot filament CVD apparatus used for diamond formation in an example of the present invention.

FIG. 8 is a schematic diagram of a microwave plasma CVD apparatus used for diamond formation in an example of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Heater 2 ... Ceramics substrate 3 ... Heating resistor 4 ... Electrode terminal part 5 ... Si substrate 6 ... Insulation protective layer 7 ... Temperature measuring element 8 ... Heater holder 9 ... Back heat insulation layer 10 ... Heat resistant film 11 ... Pressure roller 12 ... Electrode tab 13 ... Brazing material 14 ... Wire 15 ... Fixing nip 16 ... Recording material 17 ... Unfixed toner 20 ... Quartz reaction tube 21 ... Electric furnace 22 ... Tantalum filament 23 ... Substrate 24 ... Gas inlet 25 ... Exhaust outlet 26 ... Quartz reaction tube 27 ... Substrate 28 ... Gas introduction system 29 ... Microwave power source 30 ... Microwave waveguide 31 ... Vacuum exhaust system

Claims (2)

[Claims] 1. A heater having an insulating substrate, a resistance layer supported by the insulating substrate and generating heat when energized, and an electrode terminal portion provided at an end portion of the resistance layer, wherein a gas phase is used as a protective layer for the resistance layer. A heater characterized by using a diamond layer formed by a synthetic method. 2. A method for manufacturing a heater having an insulating substrate, a resistance layer supported by the insulating substrate and generating heat when energized, and an electrode terminal portion provided at an end portion of the resistance layer, wherein a protective layer for the resistance layer is provided. A method for manufacturing a heater, characterized in that the diamond layer is formed by a vapor phase synthesis method.