KR20050043612A - Plate-shape heater, fixing device and image forming device - Google Patents

Abstract

SUMMARY OF THE INVENTION An object of the present invention is to restrict the width of a long substrate and the formation width of the resistance heating element formed on the substrate, thereby reducing the heat capacity of the substrate with respect to the resistance heating element, thereby improving the temperature rise characteristic and suppressing the occurrence of cracking of the substrate. An object of the present invention is to provide a plate heater that can be used, a fixing apparatus using the plate heater, and an image forming apparatus equipped with the fixing apparatus.

Glass, an inorganic oxide and / or an elongated substrate 1 made of a heat-resistant and electrically insulating material and an Ag / Pd alloy formed in a band shape on the surface of the substrate 1 with a width of 70% or more of the substrate width along the longitudinal direction. Fixation using plate heater (H1) and plate heater (H1) provided with a resistance heating element (2) containing inorganic nitride, and power supply terminal portions (3, 3) formed in succession to the resistance heating element (2). An apparatus 7 and an image forming apparatus 9 on which the fixing apparatus 7 is mounted.

Description

Plate Heater and Fusing Device and Image Forming Device {PLATE-SHAPE HEATER, FIXING DEVICE AND IMAGE FORMING DEVICE}

The present invention provides a plate heater used as a heating source in an OA machine, a home electric appliance, a precision manufacturing apparatus or a test research facility, or a toner fixing apparatus for an OA machine such as a copying machine or a facsimile on which the plate heater is mounted, and the fixing apparatus. It relates to an image forming apparatus.

For example, in an electronic copier, the toner image formed on the surface of the photosensitive drum is transferred to a copy paper or a copy film, which is a heating object, and then passed through the copy paper while being pressed between the plate heater and the pressure roller, and then to the heat of the plate heater. The copy paper is heated to melt the toner to fix it.

This type of conventional plate heater has Ag and Pd on the surface of a planar elongated substrate made of heat-resistant and electrically insulating ceramic material such as Al ₂ O ₃ (aluminum oxide), AlN (aluminum nitride), or SiC (silicon carbide). A paste containing a mixture of (silver and palladium) alloy powder, a glass powder (inorganic binder) and a water-soluble organic binder is printed and fired to obtain a TCR (resistance temperature coefficient) having a thin strip-shaped film thickness of 200 ppm / 占 폚 to 1000 A resistance heating element is formed at about ppm / ° C.

In addition, a feed terminal portion made of a film such as Ag (silver) or Pt (platinum), which is electrically conductive, is formed on both ends of the resistance heating element from the material for forming the resistance heating element, and the surfaces of the resistance heating element and the substrate are insulated from each other. It is coated with this good glassy overcoat layer to protect the resistance heating element from abrasion, impact, and the like, and to protect it from oxidation, sulfidation, electric shock, and the like.

Such a plate heater is advantageous in that it can be thinner and smaller than a tubular light bulb or a tubular heater and at the same time closer to the heating element, resulting in high thermal efficiency and power saving.

However, it has been found that, for example, when the plate heater mounted on the fixing device of the image forming apparatus is intermittently energized and used, problems may occur in the temperature rise characteristic and the substrate.

That is, this type of plate heater is energized because the resistance heating element formed on the surface of the substrate is a strip-shaped film member having a width of about 1/8 to 1/2 of the width of the substrate, and the heat capacity of the ceramic substrate is very small. Heat of the resistive heating element which is directly raised by the electric wave propagates to the substrate, and there is a problem in that it takes a long time to raise the temperature as a heater.

In addition, the plate heater also has a problem that the substrate is cracked due to a thermal shock due to a temperature difference between the portion of the resistance heating element that becomes high in a short time (instantaneous) consisting of the TCR (resistance temperature coefficient) value and the substrate whose temperature does not rise. have.

The manufacture of a ceramic substrate, for example, an alumina substrate, is performed as follows. It shape | molds into thin plate shape in which predetermined thickness was continuous by the doctor blade method, a pressure mold, etc., cuts a thin plate member to the size, and is baked by the heating furnace. Then, the laser beam is abutted according to the marking of the V-shaped concave grooves or the like formed vertically and horizontally in the thin plate member in accordance with the size of the substrate at the time of forming or after the formation of the large thin plate member, and the thin plate member is cut into a rectangle having a predetermined size to produce a large quantity Get a long substrate.

In the case of cutting the thin plate member made of ceramics with a laser, it is heated and melted at a high power density to cut it, or a concave groove is formed by a laser at a cut scheduled portion of the thin plate member, and then mechanically bent into the concave groove in a step. Separate to obtain each substrate. However, the substrate has a burr-shaped ridge of ceramic fine powder residue that is melted and evaporated and adhered along the cutting edge portion (or the concave groove edge portion for cutting) on the incident surface side of the laser, or a small crack occurs. The periphery of the cut substrate is in an uneven state.

The heater completed by forming a resistive heating element or the like by using such a substrate has a burr around the periphery due to a thermal shock in which the substrate is intermittently repeated with heat generation or cooling (stand-by-rest) due to a temperature difference with the resistive heating element or energization. In some cases, the cracks are greatly extended from the micro cracks, resulting in cracks or cracks in the substrate.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and by regulating the width of a long substrate and the formation width of a resistive heating element formed on the substrate, the heat capacity of the substrate for the resistive heating element can be reduced to improve the temperature rise characteristic. An object of the present invention is to provide a plate heater capable of suppressing the occurrence of cracks in a substrate, a fixing apparatus using the plate heater, and an image forming apparatus equipped with the fixing apparatus.

The plate heater according to claim 1 of the present invention comprises a long substrate made of a heat-resistant and electrically insulating material, a Ag / Pd alloy formed on a surface of the substrate in a band shape at a width of 70% or more of the substrate width along a length direction, and A resistance heating element comprising an inorganic oxide and / or an inorganic nitride, and a power supply terminal portion formed by successively being provided to the resistance heating element are characterized by being provided.

The plate heater according to claim 1 is characterized in that the width of the resistance heating element formed of a conductor component composed of an Ag / Pd (silver / palladium) alloy and a resistor component composed of glass and an inorganic oxide and / or an inorganic nitride, and a long ceramics The ratio of the width of the resistive heating element to the width of the substrate is larger than that of the conventional one. In other words, the ratio of the width of the substrate to the width of the resistive heating element is made smaller than before. The area of the resistance heating element that generates heat during energization is large, thereby increasing the temperature of the entire substrate surface in a short time, thereby increasing the rising characteristics that can shorten the rise time of the heater temperature.

That is, the temperature rise characteristic of a heater can be improved by increasing the heat generating area ratio of a board | substrate surface.

When the placement width of the resistive heating element with respect to the width of the substrate is less than 70%, the heat generation area of the substrate is low and the amount of heat deprived to the large capacity substrate is large, requiring time for temperature rise as a heater and rapidly requiring high temperature. Not suitable for heaters. Moreover, although 100% may be sufficient as an upper limit, when considering the thing which insulates a resistance heating body with an overcoat layer, up to about 90% is practically preferable.

The resistive heating element is formed of an Ag / Pd alloy in which the conductor component is contained, one containing amorphous binding glass, an inorganic oxide and / or an inorganic nitride having electrical insulation, or a small amount of another material added thereto.

The amorphous glass having electrical insulation added to the Ag-Pd alloy has not only a function as a binder for fixing film, but also has electrical insulation, so that the added amount is increased and decreased to have a function of adjusting resistance as a resistor component.

In addition, the inorganic oxide and / or inorganic nitride which have electrical insulation means that it does not interfere even if it contains compounding (addition) of at least 1 type or multiple types of material of an inorganic oxide or an inorganic nitride.

For example, the weight ratio (Ag / Pd) of the Ag / Pd alloy constituting the resistance heating element is 95/5, 75/25, or the like, so as to reduce the amount of relatively expensive Pd used. In addition, the amount of the inorganic oxide or the inorganic nitride added to the weight of the Ag / Pd alloy of the resistance heating element is about 0.1 to 20% by weight, and the amount of the inorganic oxide, the inorganic nitride and the amorphous glass is about 10 to 70% by weight. The ratio of the conductor component, inorganic oxide and / or inorganic nitride or glass, and the specific material constituting the resistive heating element and the selection of the specific material are appropriately within the regulatory ranges such as the heater rating, characteristics (temperature rise, TCR, etc.), shape, etc. required. You can choose.

In addition, when the content (addition) of the inorganic oxide and / or the inorganic nitride as a filler to the weight of the Ag / Pd alloy is less than 0.1 wt%, a large amount of glass must be added to adjust the resistance of the heating element, so that the heating element is a substrate. And foaming between the glass of the wiring conductor and the overcoat layer, or a large variation in the resistance value, and when the amount of the inorganic oxide exceeds 20% by weight, the adhesion strength of the heat-generating film is lowered and is likely to cause peeling. There is a problem.

In addition, when the addition amount containing an inorganic oxide, an inorganic nitride, and an amorphous glass is less than 10 weight%, the width | variety which makes it impossible to form the resistor of the high resistance value range of 100 mPa-several ohms / square, and lengthens the whole length of a heat generating body narrowly There is a problem that the pattern design of the heating element is limited.

In addition, when the total weight exceeds 70% by weight, there is a problem that the heating element is foamed by the reaction of the substrate, the conductor, the glass of the overcoat layer, or the like, and the variation in the resistance value becomes large.

In addition, in the description of the specification of the present invention, the definitions and technical meanings of terms are as follows unless otherwise specified.

As a board | substrate, what covered the said electrically insulating material which consists of the said ceramics and high heat resistant glass etc. can be used for the ceramics and metal plate which can withstand high temperature as well as electric insulation.

In addition, one or more or a plurality of resistance heating elements are formed on the surface of the substrate in a straight form, are connected in series or in parallel to the power supply, and terminal portions for power feeding are formed at the ends or intermediate portions thereof.

In addition, as a terminal part for electric power feeding, the film | membrane formed from the electrically conductive metal material mainly consisting of Ag (silver), Ag, Pt (silver-platinum alloy), Au (gold), Pt (platinum), etc., or a separate metal foil, plate material It may be formed by a wire or the like.

The plate heater of the present invention may be provided with a temperature detection sensor, a switch, etc. made of a thermistor, a thermocouple, a thermostack, or the like, on the side of the substrate opposite to the surface on which the resistance heating element is formed.

When the sensor for temperature detection is provided on a board | substrate, temperature control can be performed by correctly sequence | heating the temperature of a heater, detecting the resistance change with high precision, and feeding this back to a temperature control circuit. The temperature detection sensor may be installed directly on the board together with the wiring conductor or may be mounted on the board, and the wiring conductor electrically connected to the sensor may be formed by a film like the terminal portion of a feed type film. It may be formed by, for example.

The plate heater according to claim 2 of the present invention is characterized in that the substrate is made of at least one ceramic material of AlN, Si ₃ N ₄ , Al ₂ O _3, or SiC.

As substrates, nitride ceramics such as AlN (aluminum nitride) and Si ₃ N ₄ (silicon nitride), which are excellent in heat resistance, weather resistance and electrical insulation, oxide ceramics such as Al ₂ O ₃ (aluminum oxide) or SiC (silicon carbide) Formation of carbide-based ceramic materials such as these can prevent occurrence of cracks and cracks.

The plate heater according to claim 3 of the present invention has a width of the substrate of 3 to 7 mm.

If the width of the substrate is less than 3 mm, the rapid heating is high, but the heat amount is small. For example, in the case of a fixing device or the like, the heat amount required for fixing the non-heating toner cannot be transmitted. In addition, if the width exceeds 7 mm, the desired effect is obtained. However, since the area of the portion without the resistive heating element in the substrate width direction becomes large, it is not preferable, and there is a fear of causing an increase in cost.

The plate heater according to claim 4 of the present invention is characterized in that the cut surface around the substrate is subjected to a smooth surface treatment.

In the case where the thin plate member made of ceramic is cut directly or indirectly with a laser beam, the periphery of the substrate is in an uneven state such as burr-shaped ridges of fine ceramic residue or fine cracks are formed on the cut surface. Although many things have arisen, the peripheral part of the board | substrate divided from the board member is chamfered by means, such as grinding, and it is set as the smooth surface.

This smoothing does not mean a precise smooth surface, but refers to the extent to which unevenness and damage are invisible to the eye, and the burrs and minor cracks at the periphery may be excluded.

By performing such a process, even if heat shock etc. are applied to the board | substrate of a heater after ON-OFF is intermittently performed repeatedly, it can prevent that a small crack grows and progresses to a big crack or a crack.

In the plate heater according to claim 5 of the present invention, the glass in the resistance heating element is ZnO-SiO ₂ -based, B ₂ O ₃ -ZnO-based, SiO ₂ -Al ₂ O ₃ -based, B ₂ O ₃ -SiO-ZnO-based, SiO _It is characterized by consisting of at least one amorphous glass of ₂ -Al ₂ O ₃ -CaO system or B ₂ O ₃ -BaO-ZnO system.

These ZnO (zinc oxide)-SiO ₂ (silicon oxide) type, B ₂ O ₃ (boron oxide)-ZnO (zinc oxide) type, SiO ₂ (silicon oxide)-Al ₂ O ₃ (aluminum oxide) type, B ₂ O ₃ (boron oxide)-SiO ₂ (silicon oxide)-ZnO (zinc oxide) type, SiO ₂ (silicon oxide)-Al ₂ O ₃ (aluminum oxide)-CaO (calcium oxide) type or B ₂ O ₃ (oxidation) Boron)-BaO (barium oxide)-ZnO (zinc oxide) -based amorphous glass has excellent fluidity during melting to prevent foaming, thereby obtaining an intimate heating element (membrane) and acting as a binder for fixing film. The adhesion to the substrate can be enhanced to prevent peeling.

In addition, since amorphous glass has electrical insulation properties, the resistance value can be adjusted as a resistor component by increasing or decreasing the amount of the additive added in the heating element (film) forming step. At the same time, a wide range of resistance values can be easily obtained with the paste type and the same composition.

In addition, although crystallized glass may be used as the binder glass, crystallized glass crystallizes due to heating and loses fluidity. As a result, the heating element (membrane) tends to be porous, and at the same time, the resistance is changed by changing the crystal state. easy.

The plate-shaped heater according to claim 6 of the present invention, the inorganic oxide or inorganic nitride in the resistance heating element at least one of _{SiO 2, Al 2 O 3,} TiO 2, ZrO 2 and SiO _2, 2MgO and 2Al ₂ O ₃ and 5SiO ₂ or AlN It is characterized by consisting of one kind.

SiO ₂ (silicon oxide), Al ₂ O ₃ (aluminum oxide), TiO ₂ (titanium oxide), ZrO ₂ ㆍ SiO ₂ , 2MgO · 2Al ₂ O ₃ ㆍ 5SiO ₂ (co-made) which is excellent in heat resistance and weather resistance and electrical insulation By adding and blending one kind or a plurality of kinds of inorganic oxides or inorganic nitrides made of light; cordierite) or AlN (aluminum nitride) as a funnel, the amount of glass can be suppressed by adjusting the resistance value.

In addition, it is possible to prevent foaming or deterioration of the glass between the substrate, the resistance heating element, the wiring conductor and the overcoat layer, to suppress variation or fluctuation of the resistance value during manufacture, and to easily obtain a wide range of resistance values with the same composition as a paste.

The plate heater according to claim 7 of the present invention is characterized in that a glassy overcoat layer is formed on the surfaces of the resistance heating element and the substrate.

The glassy overcoat layer formed on the surface of the resistive heating element and a part of the substrate prevents the resistive heating element from being deteriorated due to oxidation or sulfidation and thus changes in resistance, and protects against damage or abrasion due to electrical insulation and contact. Achieve.

The overcoat layer is made of PbO (lead oxide)-B ₂ O ₃ (boron oxide)-SiO ₂ (silicon oxide) based glass, ZnO (zinc oxide)-SiO ₂ (silicon oxide)-BaO (barium oxide) based Glass, SiO ₂ (silicon oxide)-ZnO (zinc oxide)-Al ₂ O ₃ (aluminum oxide) based glass, SiO ₂ (silicon oxide)-B ₂ O ₃ (boron oxide)-Al ₂ O ₃ (aluminum oxide) ) Free SiO ₂ (silicon oxide)-B ₂ O ₃ (boron oxide)-ZnO (zinc oxide) based glass or SiO ₂ (silicon oxide)-B ₂ O ₃ (boron oxide)-Na ₂ O (sodium oxide) When formed from a glass-based material, the reaction with the material constituting the resistance heating element is small or does not occur at all.

In addition, by adding a filler such as SiO ₂ (silicon oxide), AlN (aluminum nitride), BN (boron nitride) or SiC (silicon carbide) to these glass materials, the thermal conductivity can be improved.

The fixing apparatus according to claim 8 of the present invention includes a pressurizing roller and the plate heater according to any one of claims 1 to 7 in which a resistance heating element is disposed to face the pressing roller.

Since the plate heater which exhibits the effect | action of Claim 1 thru | or 7 is provided, the fixing apparatus which performs ON (energization)-OFF (standby or pause) repeatedly intermittently, the temperature rise at the time of energization is quick At the same time as the fixing speed is increased, the repair caused by the heater which does not cause cracks or cracks on the substrate can be easily performed.

In the fixing apparatus, copying paper or the like is supplied between the roller and the plate heater through the rolled heat-resistant sheet by the rotation of the pressure roller. If there is an uneven portion such as a burr, the heat-resistant sheet or copy paper that comes into contact with the uneven portion may not be smoothly conveyed, but if it is severe, there is a problem of damaging the copy paper or the like. The contact with the copy paper or the like is also good, and they are not damaged.

Moreover, in this fixing apparatus, you may interpose the protection member which does not interfere with the permeation | transmission of a hot wire between a plate heater and a to-be-heated body, and the film etc. for conveying copy papers etc. which are a to-be-heated body are provided in the copying machine etc., too. good.

An image forming apparatus according to claim 9 of the present invention includes means for attaching a toner to an electrostatic latent image formed of a medium, transferring the toner to a coated yarn member to form a predetermined image, and forming an image by a pressure roller. A fixing apparatus according to claim 8 is provided, wherein the toner is fixed by passing the copying member in a press-contact with a plate heater.

With a copying machine, a printer, etc. provided with the fixing apparatus which exhibits the function of Claim 8, the temperature rise at the time of energization of a fixing heater can be quick, and the repair resulting from this heater can be performed easily.

The copy paper used in the present invention is a generic term for a paper, a film, or the like to which a document, a spot or the like is copied.

EMBODIMENT OF THE INVENTION Hereinafter, embodiment of the plate heater which concerns on this invention is described with reference to drawings. FIG. 1 is a front view showing the middle portion of the plate heater H1 cut out, FIG. 2 is a rear view of the plate heater H1 shown in FIG. 1, and FIG. 3 is a portion cut along the arrow marks a-a in FIG. (In addition, the thickness and width of each layer, such as a resistance heating element, a power supply terminal part, a wiring conductor, and an overcoat layer, with respect to the board | substrate shown in each drawing are exaggerated, and are not proportional as a dimension. In addition, the front surface side surface and back surface surface of a board | substrate are things in description of drawing, and may reverse in practical use.

In the drawings, reference numeral 1 denotes a nitride-based ceramic material such as AlN (aluminum nitride) as a main component, for example, having a length of about 300 mm, a width (BW) of about 6.1 mm, and a thickness. It is a long substrate of about 0.7 mm.

In addition, 2 is connected to the front surface side 1a surface of this board | substrate 1, and is formed by connecting so that it may return between intermediate ends among four sets of heat-generating parts 21, ... (about M-shaped) It is a continuous strip-shaped resistance heating element. The resistance heating element 2 has four sets of heat generating parts 21, 21, 21, and 21 with a gap (w, w, w) of about 0.5 mm, a width (HW) of about 1.0 mm, and a thickness of about 10 micrometers and the length of one side are formed in about 280 mm. The width CW is the heat generating portion 21 of the resistance heating element 2 from the shortest point 31 on one side of the substrate 1 to the shortest point 32 on the other side of the substrate, as shown in FIG. The width including the interval w of. This width CW corresponds to the width HW of the resistance heating element 2 itself in the embodiment shown in FIG. 5 described later.

The material of the resistance heating element 2 is made of Ag (silver) Pd (palladium) alloy as a conductor component, and an inorganic oxide having electrical insulation, for example, Al ₂ O ₃ (aluminum oxide), is used as a funnel. In addition, a frit of amorphous glass of SiO ₂ -Al ₂ O ₃ system is added and blended thereto, and the glass frit is fixedly attached to the surface of the front surface side 1a of the substrate 1 as a binder. have. In addition to acting as a binder, this glass frit is an electrical insulator and also acts for resistance adjustment.

Reference numerals 3 and 3 denote terminal portions formed of wide feeder type film electrodes formed on the surface of the front surface side 1a near the end of the substrate 1 as an intermediate layer above or below the end of the resistance heating element 2. And a conducting film thickness mainly composed of Ag, Pt (silver, platinum) alloys or the like (the terminal portion 3 for power supply may be formed so as to have a high film thickness and low resistance).

Further, reference numeral 4 is an overcoat layer of glass, SiO ₂ a SiO ₂ (silicon oxide) as a main component (silicon oxide) - ZnO (zinc oxide) is made of a glass of Al ₂ O ₃ (aluminum oxide) type, the It forms on the surface of the both ends of the terminal part 3 for electric power feeding and the board | substrate 1 from the resistance heating element 2 along the longitudinal direction. That is, a glassy overcoat layer 4 having a layer thickness of 20 µm to 100 µm is formed so as to cover most of the entire surface except for a part of the terminal portions 3, 3.

Further, reference numerals 51 and 51 denote wiring conductors formed by forming the terminal portion 3 and the material on the back surface side 1b of the substrate 1, reference numerals 52 and 52 denote terminal portions of the wiring conductors 51 and 51, Between the distal ends of the wiring conductors 51 and 51, a sensor for temperature detection, for example, a thermistor 6 made of an NTC element, is joined via a conductive adhesive in which Ag / Pd alloy powder or the like is mixed with a resin.

Next, the manufacturing method of this plate heater H1 is demonstrated. First, the elongated substrate 1 made of AlN (aluminum nitride) and having a smooth periphery, and Ag 92 weight% Pd 8 weight% alloy powder, and SiO ₂ -Al ₂ O ₃ -based amorphous glass frit powder for binder and resistance adjustment, about 20 weight% with respect to said Ag. Pd alloy, and the funnel The inorganic oxide powder made of Al ₂ O ₃ as a filler is about 10% by weight based on the total weight of the Ag, Pd (silver, palladium) alloy powder, ethyl cellulose (organic adhesive), and terpineol. The heating element paste which mixed the organic solvent is prepared.

Then, the heating element paste is connected in series to the predetermined forming portion on the front surface side 1a surface of the substrate 1 having a width BW of about 6.1 mm along the lengthwise direction, and connected to each other in series by about 0.5 for each other. A coating film composed of four sets of film thicknesses of about 1.0 mm is formed with a gap (w) of mm interposed therebetween. At this time, the gap between the outermost coating film outer edge and the periphery of the substrate 1 is about 0.3 mm. Thereafter, the coating film is dried and fired in a firing furnace at a firing peak temperature of about 850 ° C. for about 10 minutes.

By this firing, the binders contained in the paste are evaporated and scattered to melt the glass component, which is an inorganic binder, and fix the mixed powder of the Ag / Pd alloy and the inorganic oxide to the surface of the front surface side 1a of the substrate 1. The resistive heating element 2 is formed of the heat generating portions 21,... Of the four-thickness film having a width HW electrically insulated from each other by being attached to each other.

Subsequently, for example, a material having an electric resistance per unit area smaller than that of the resistance heating element 2 on the end and the back surface 1b surface of the resistance heating element 2 extending at both ends of the front surface side 1a surface of the substrate 1, for example. The conductive paste containing the Ag / Pt alloy as a conductive component is applied by screen printing, dried, and then fired as described above, whereby the terminal portions 3 and 3, the wiring conductors 51 and 51 and the terminal portions of the film thickness type for power feeding ( 52, 52).

In addition, after drying the coating film of the said resistance heating body, after apply | coating and drying an electrically conductive paste, you may make it bake both coating films simultaneously.

Thereafter, the overcoat layer 4 is formed. This is because, for example, a glass paste obtained by mixing SiO ₂ -ZnO-Al ₂ O ₃ -based glass powder containing SiO ₂ as a main component and an organic solvent together with ethyl cellulose (organic binder) in the resistance heating element (2). ), A coating film is formed continuously on the part of the terminal portions 3 and 3 for power feeding and on the surface portions of both end portions along the longitudinal direction of the front surface side 1a of the substrate 1 without gaps.

After the coating film is dried, the firing peak temperature is fired in the firing furnace at about 850 ° C for about 10 minutes to form a glassy overcoat layer 4 having a thickness of 15 µm to 100 µm.

The glass paste is lower than the firing temperature of the paste-type paint constituting the resistance heating element 2 at a softening point of about 600 to 800 ° C., and when the firing temperature is increased, the glass paste formed on the front surface side 1a surface portion is melted. Thus, a smooth glassy overcoat layer 4 having a flat surface portion and no unevenness is formed.

In addition, in the final process, the thermistor 6 is bonded to the wiring conductors 51 and 51 through the conductive adhesive formed by mixing Ag and Pd alloy powder etc. with glass (inorganic binder) or water-soluble organic binder, respectively. have.

The plate heater H1 having such a configuration is energized with a circuit configuration as shown in FIG. That is, when the terminal parts 3 and 3 for power supply are energized through the temperature control circuit T, a current flows through the resistance heating body 2, and the resistance heating body 2 generates heat. At this time, the signal current also flows through the thermistor 6.

The substrate 1 is also heated by the heat generated by the resistance heating element 2, and the temperature rises. This heat is applied to the heat-sensitive portion of the central portion of the thermistor 6 mounted on the rear surface side 1b of the substrate 1. It is transmitted to change the resistance value of the thermal portion. The change in the resistance value of the heat-sensitive portion is outputted from the terminal portions 52 and 52 through the wiring conductors 51 and 51, and inputted to the temperature control circuit T to determine whether or not it is in a preferable temperature range. The power applied to) is adjusted by, for example, phase control to adjust the temperature. In addition, this temperature control is not limited to phase control of electric power, but may be adjusted to a predetermined temperature range by controlling voltage and current.

In addition, although not shown, as a safety device (circuit) in this kind of apparatus, multiple safety devices, such as a temperature fuse and a current fuse other than this temperature control circuit T, are provided in parallel.

The plate heater H1 has a total width HW of the strip-shaped resistance heating element 2 formed on the substrate surface of 4 mm (for 1 mm × 4 pieces), and a width of the substrate 1 BW of 5.5 mm. . When there is little space | interval w between the heat generating parts 21 of the resistance heating body 2, the width CW occupies about 73% with respect to the width BW of the board | substrate 1. As shown in FIG. In this case, since most of the front surface side 1a of the substrate 1 heats up, and at the same time, the width of the substrate 1 is reduced, the heat capacity of the substrate 1 is reduced, and the heating rate of the heater H1 is increased quickly. do. In other words, the temperature of the entire substrate 1 is increased almost uniformly for a short time after the energization, so that the temperature rise characteristic is improved to provide a compact plate-shaped heater H1.

In addition, since the heat capacity of the heater H1 is reduced, the heater H1 also has a small temperature difference from the heat generating resistance heating element 2, and for example, the ON (energization)-OFF (standby or pause) of the heater is intermittently interrupted. Even if it is performed repeatedly, crack generation of the board | substrate 1 by the thermal shock resulting from a temperature difference can be suppressed.

In addition, since the heater H1 using the substrate 1 smoothed by grinding or the like at the time of forming is removed, fine cracks are removed, so that cracks and cracks are formed on the substrate 1 due to thermal shock such as a temperature difference. It does not cause it.

In addition, this plate heater has a resistance heating element 2 formed of a conductor component of Ag 92% by weight and Pd 8% by weight, and its TCR value exceeds 1000 ppm / ° C, even when a safety circuit such as a device does not operate. The excessive rise of the temperature of the heater H1 can be prevented, and there is no problem of thermally affecting the heater H1 itself, the holding member, or other components other than those present in the vicinity. In addition, even if a high power is input from the rated value, a temperature difference is less likely to occur in the substrate 1, so that there is no crack or crack in the substrate 1.

In addition, when the ratio of Pd having a large specific resistance is reduced to 10% or less, it is possible to form a resistor having a low resistance value range of several mPa / □, and return the resistance heating element 2 to the entire surface of the substrate 1. It can be arrange | positioned etc. and formed long, and it is easy to raise the area ratio with respect to the board | substrate 1.

Therefore, according to the present invention, since the ratio of the area of the resistive heating element 2 to the area of the substrate 1 is large, the improvement of the temperature rise characteristic which is high in heat generation efficiency and quick after heating is attempted, The generation | occurrence | production of the crack and crack can be suppressed, and the plate-shaped heater H1 which tried to miniaturize can be provided.

5 is a front view showing another embodiment of the plate heater H2 of the present invention. The same parts as those in FIGS. 1 to 3 described above are given the same reference numerals, and description thereof will be omitted.

In the plate heater H2 shown in the present embodiment, the width BW of the substrate 1 is about 3.3 mm, and the front surface side 1a of the substrate 1 has the same material composition as that shown in the above embodiment. The pair of resistance heating elements 2 having a width HW of about 2.6 mm is formed.

Such a heater H2 also has a width of the resistive heating element 2 about 80% with respect to the width of the substrate 1, and can exhibit an effect similar to that of the above embodiment.

6 and 7 show an embodiment of the fixing device 7 in which the plate heaters H1 and H2 are assembled. This fixing device 7 is for a copying machine, FIG. 6 is a longitudinal sectional view in which part thereof is cut out, and FIG. 7 is an enlarged cross sectional view of a cutting plane along the arrow line b-b in FIG. 6, and the portion of the heater H1 in the figure. Since is the same as the above embodiment, the description is omitted.

In the figure, reference numeral 71 denotes a pressure roller, and protrudes a rotating shaft 72 pivotally supported by a drive unit (not shown) on both end faces of the cylindrical roller body 73 formed on the outer circumference of the rotating shaft 72. A heat resistant elastic material, for example, a silicone rubber layer 74, is fitted to the surface.

In addition, reference numeral 81 denotes a heater support member which is disposed to face the rotation shaft 72 of the pressure roller 71, and the plate heater H1 is formed in the recess 82 of the support member 81 by the pressure roller 71. It is fixed in the state juxtaposed by Moreover, around the support member 81 containing the heater H1, the endless roll-shaped fixing film 83 which consists of heat resistant sheets, such as a polyimide resin, is wound-wound-mounted.

The smooth surface of the glassy overcoat layer 4 formed above the heater H1 is elastically bonded to the silicone rubber layer 74 of the pressure roller 71 via the fixing film 83. In the figure, P denotes a recording medium such as a copy paper or a film for forming a heated object, in this case, a copy paper, where T1 on the copy paper P is an unfixed toner image printed on it, and T2 is a fixing toner image. .

The fixing device 7 having the above-described configuration is used as a part of the image forming apparatus 9 to fix the unfixed toner image T1 transferred to the coated yarn member such as the copy paper P as described later.

In this fixing device 7, the plate heater H1 is energized through the connectors 85 and 85 that are elasticized by bending the phosphor bronze plate in contact with the terminal portions 3 and 3, for example. Pressure roller 71 rotates by the drive part in the state which heat | fever to the predetermined temperature, and the fixing film 83 which is driven and pressed by this also makes sliding heater contacting the surface of the overcoat layer 4 which covers plate-shaped heater H1. It circulates around the support member 81.

Then, when the copy paper P on which the unfixed toner image T1 has been transferred is conveyed to the fixing device 7, the copy paper P is upper and lower surfaces of the silicon rubber layer 74 of the pressure roller 71 and the fixing film. While both of the (83) planes are rotating, they are made to pass in the direction of the arrow in the figure in the state of being pinched from the upper and lower surfaces. At that time, the copy paper P is baked by the above-mentioned pressurization and heating of the resistance heating element 2, whereby the unfixed toner image T1 is baked to fix the toner image T2 on the copy paper P. .

That is, on the paper input side of the pressure roller 71, the unfixed toner image T1 on the copy paper P is first heated and melted by the heater H1 through the fixing film 83, and at least the surface portion thereof has a large melting point. Melt and melt completely. Then, on the paper discharge side of the pressure roller 71, the copy paper P is separated from the heater H1, and the toner image T2 is naturally radiated to cool and solidify again, and the fixing film 83 is also removed from the copy paper P. Spaced apart.

At this time, since the smooth surface of the glassy overcoat layer 4 formed by covering the resistance heating element 2 of the plate heater H1 as the uppermost layer is in sliding contact with the fixing film 83, the fixing film 83 This smooth rotation allows the copying paper P to be smoothly conveyed together with the fixing film 83 between the pressure rollers 71, and good fixing with little toner seepage can be performed.

Next, a description will be given with reference to the copying machine 9 shown in Fig. 8 as an image forming apparatus incorporating the plate heater H1 and the fixing device 7 according to the present invention. Fig. 6 is a longitudinal sectional view showing a schematic configuration of an image forming apparatus, for example, a copying machine 9, on which the fixing device 7 is mounted. In the drawing, the fixing device 7 portion is the same as the above embodiment, The same code | symbol is attached | subjected and the description is abbreviate | omitted.

In Fig. 8, reference numeral 90 denotes a housing of the copier 9, 91 denotes a document P1 by reciprocating in the direction of the arrow Y in a document mount made of a transparent member such as glass provided on the upper surface of the housing 90. .

Above the housing 90, an illuminating device 9L composed of a lamp for light irradiation and a reflecting mirror is provided, and the reflected light from the document P1 irradiated by the illuminating device 9L is a short focal small diameter imaging element. Slit exposure is performed on the photosensitive drum 9D by the array 9A. This photosensitive drum 9D rotates in the direction of the arrow.

Reference numeral 92 denotes a charger, and for example, charging is uniformly performed on the photosensitive drum 9D coated with a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. In the drum 9D charged by the charger 92, an electrostatic image subjected to image exposure by the imaging element array 9A is formed. This electrostatic image is developed using a toner made of a resin or the like softened and melted by heating by the developing unit 93.

On the other hand, the copy paper P housed in the cassette 9C is rotated by a conveying roller 95 which is pressed in the up and down direction by timing in synchronization with an image on the feeding roller 94 and the photosensitive drum 9D, It is fed onto the drum 9D. Then, the toner image formed on the photosensitive drum 9D by the transfer discharger 96 is transferred onto the copy paper P. As shown in FIG.

Thereafter, the paper P separated from the drum 9D is guided to the fixing device 8 by the conveyance guide 97 and is discharged into the tray 98 after being subjected to heat fixation processing. After the toner image is transferred, the residual toner on the drum 9D is removed by the cleaner 99.

The fixing device 8 is formed in a direction orthogonal to the moving direction of the copy paper P, and has an effective length matched with the width (length) of the maximum sheet paper that can copy the copying machine 9, that is, the maximum sheet paper. Pressurizing roller for transfer against the heat generating resistor 3 so as to extend the heat generating resistor 3 longer than the width (length) to arrange the plate-shaped heater H1 and to elastically bond lightly in the extending direction of the heater H1. 71 is provided.

Then, the unfixed toner image T1 on the sheet of paper P conveyed between the heater H1 and the pressure roller 71 is melted by receiving heat from the resistance heating element 2, and then on the surface of the sheet of paper P, characters and zeros. Make copies of numbers, symbols, drawings, etc. appear.

Such a copying machine 9 incorporating the fixing device 7 is capable of rapidly increasing the copying speed at the same time, even if ON (energizing)-OFF (standby) is repeatedly performed intermittently, and at the same time, the substrate 1 ), There is no breakdown caused by cracks or cracks, so maintenance is easy.

In addition, this invention is not limited to the said embodiment. For example, in the above embodiment, the plate heater is used for fixing the copier, but can also be applied to fixing other OA devices such as printers and facsimiles.

In addition, the present invention is not limited to an OA device, and can be used by being used for heating in household electrical appliances, precision devices for business and experiments, or devices for chemical reactions.

According to the invention described in claim 1 of the present invention, the capacity of the substrate is reduced to increase the heating rate of the heater, and at the same time, the temperature difference between the substrate and the resistance heating element that generates heat is also reduced, and the heater is turned on (energized)-OFF (standby or idle). Even if) is repeatedly performed intermittently, the thermal shock caused by the temperature difference can be alleviated. In addition, since the reduction of the width of the substrate is attempted, there is also an advantage of miniaturizing the plate heater.

Therefore, it is possible to provide a plate heater which attempts to improve the temperature rise characteristic and to prevent occurrence of cracks or distortion of the substrate.

According to the invention of claim 2, there is provided a plate heater having an effect as described in claim 1, wherein the substrate is formed of a ceramic material having excellent heat resistance, weather resistance, electrical insulation, and the like, thereby preventing the occurrence of cracks and cracks. Can provide.

According to the invention as set forth in claim 3, it is possible to provide a high-efficiency plate heater capable of securing the amount of heat generated for fixing the toner, for example.

According to the invention of claim 4, the circumferential portion of the ceramic substrate is chamfered by means of grinding or the like to remove burrs, microcracks, and the like to form a smooth surface, whereby ON (energization)-OFF (standby or pause) is intermittent. Even if a thermal shock such as repeatedly performed on the substrate is applied, a plate heater having an effect as described in claim 1 which can prevent the occurrence of cracks and cracks can be provided.

According to the invention as set forth in claim 5, the amorphous glass contained in the resistance heating element (film) can adjust the resistance value as a resistor component by increasing or decreasing the addition amount thereof, and also obtain an intimate film and act as a binder and have a substrate. It is possible to provide a plate heater that tries to prevent peeling by increasing adhesiveness with.

According to invention of Claim 6, the plate-shaped heater which exhibits the effect which the inorganic oxide or inorganic nitride contained in the resistance heating body (film) prevents foaming or alteration of glass, and suppresses fluctuations or fluctuations of a resistance value. .

According to the invention as set forth in claim 7, the glassy overcoat layer prevents the resistance heating element from being changed by oxidation or sulfidation, thereby changing the resistance value, and at the same time, protects the plate heater from damage or abrasion due to electrical insulation and contact. do.

According to the invention of Claim 8, since it is provided with the plate heater which exhibits the effect of Claims 1-7, in the fixing apparatus which is repeatedly performed ON (energization)-OFF (waiting or resting) intermittently, In addition, the fixing apparatus which can raise the fixing speed rapidly at the time of energization, and can perform maintenance by the heater which does not generate a crack or a crack in a board | substrate easily can be provided.

According to the invention described in claim 9, a copying machine, a printer, or the like having a fixing device that exhibits the effect according to claim 8, wherein the temperature rise at the time of energization of the fixing heater is fast, and the repair caused by the heater can be easily performed. An image forming apparatus such as a copying machine can be provided.

BRIEF DESCRIPTION OF THE DRAWINGS The front view which cut | disconnected the intermediate part which shows embodiment of the plate heater of this invention.

Figure 2 is a rear view of the plate heater of Figure 1;

FIG. 3 is an enlarged cross sectional view of a portion cut along the arrow line a-a in FIG. 1; FIG.

4 is an explanatory diagram showing a configuration of an energization circuit of a plate heater according to the present invention;

Fig. 5 is a front view in which the intermediate portion is cut away showing another embodiment of the plate heater of the present invention.

Fig. 6 is a vertical cross-sectional view of a part showing an embodiment of a fixing apparatus for a copying machine of the present invention incorporating a plate heater.

Fig. 7 is an enlarged cross sectional view of the cut plane along the arrow marks b-b in Fig. 6;

Fig. 8 is a longitudinal sectional view showing a schematic configuration of an image forming apparatus (copier) of the present invention in which a fixing apparatus is assembled.

<Explanation of symbols for the main parts of the drawings>

H1, H2: Plate Heater

1: substrate

2: resistance heating element

3: Terminal part (membrane type electrode for power supply)

4: overcoat layer

7: fixing device

9: image forming apparatus (copier)

71: pressure roller

Claims (9)

A long substrate made of a heat resistant and electrically insulating material, A resistive heating element comprising glass, an inorganic oxide and / or an inorganic nitride in an Ag. Pd alloy formed in a band shape on the surface of the substrate in a longitudinal direction; It is provided with the power supply terminal part formed in succession to this resistance heating element, The width CW including a gap between the heat generating portions from one side shortest end of the substrate of the resistive heating element to the other side shortest end of the substrate is 70% or more relative to the width BW of the substrate. Plate heater. The plate heater according to claim 1, wherein the substrate is made of at least one ceramic material of AlN, Si ₃ N ₄ , Al ₂ O _3, or SiC. The plate heater according to claim 1 or 2, wherein the width of the substrate is 3 to 7 mm. The plate heater according to claim 1 or 2, wherein the cut surface around the substrate is subjected to a smooth surface treatment. The glass of the resistance heating element according to claim 1, wherein the glass in the resistance heating element is ZnO-SiO _{2 type} , B ₂ O ₃ -ZnO type, SiO ₂ -Al ₂ O _{3 type} , B ₂ O ₃ -SiO ₂ -ZnO type, SiO ₂ -Al ₂ A plate heater comprising at least one amorphous glass of an O ₃ -CaO-based or a B ₂ O ₃ -BaO-ZnO-based. According to claim 1, wherein the inorganic oxide or inorganic nitride in the resistance heating SiO _2, Al ₂ O _3, TiO _2, ZrO ₂ and SiO _2, 2MgO and 2Al ₂ O ₃ and 5SiO consisting of at least one kind of _two or AlN Plate heater, characterized in that. The plate heater according to any one of claims 1, 2, 5 and 6, wherein a glassy overcoat layer is formed on the surfaces of the resistance heating element and the substrate. With a pressure roller, The pressurizing roller is provided with the plate heater as described in any one of Claims 1, 2, 5, and 6 in which the resistance heating element is disposed to face the fixing roller. Means for attaching toner on an electrostatic latent image formed of the medium, transferring the toner to a coated yarn member to form a predetermined image; An image forming apparatus, comprising: the fixing apparatus according to claim 8, wherein the toner is formed by passing a coated yarn member on which an image is formed while being pressed against the plate heater by a pressure roller.