JPH0896937A - Heater, fixer, and image forming device - Google Patents

Abstract

PURPOSE: To provide a heater, a fixer, and an image forming device which can smoothly carry paper and besides which are easy of manufacture. CONSTITUTION: This is equipped with a slender electrical insulating board 1, where a taper part having an angle of 45 deg. or over to one face is made at a part of at least one side face in longitudinal direction and at least one end face is made lower in smoothness than the center of one face, and a resistance heater 2 which is overlaid on one side of the board. By this constitution, for the side margin of the board 1, the surface becomes very smooth, and the carriage of an object to be fixed is performed smoothly. In addition, the accuracy in dimension in longitudinal direction of the heater can be raised.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating body, a fixing device and an image forming apparatus suitable for fixing toner.

[0002]

2. Description of the Related Art Today, an image forming apparatus such as a copying machine, a printer and a facsimile is disclosed in Japanese Patent Laid-Open No. 2-1578.
The one disclosed in Japanese Patent Publication No. 86 has been put to practical use. This product forms a toner image on a paper by forming an image such as characters, figures, or images with toner, and conveys this paper with rollers etc., and heats the toner with a heating body through a carrying sheet to form a paper. Fix the toner.

As a heating element used in such an image forming apparatus, as disclosed in, for example, Japanese Patent Application Laid-Open No. 2-65086 or Japanese Patent Application Laid-Open No. 3-114755, electric resistance is provided on an electrically insulating substrate. Some have a heating element attached.

FIG. 12 is a partially cutaway front view showing another heating body of this type. Reference numeral 121 is an elongated electrically insulating substrate made of alumina ceramics or the like. 122 is, for example, a silver / palladium-based alloy (Ag / Pd) on one surface of the substrate 1.
It is a resistance heating element formed by applying a resistance paste containing as a main component by a screen printing method and firing. Both ends of the resistance heating element 122 are formed wide, and terminal layers 123, 123 containing a good conductive material such as silver (Ag) as a main component are formed on the surface of the resistance heating element 122. The surface of the resistance heating element 122 is covered with an electrically insulating coating layer 124 made of glass.

FIG. 13 is a partially cutaway perspective view showing a substrate assembly in one manufacturing process of the heating body. 1 in the figure
Reference numeral 31 is a substrate assembly formed by using, for example, a doctor blade method. A plurality of resistance heating elements 132, terminal layers 133 and 133, and an electric insulation coating layer 134 are formed on one surface of the substrate assembly 131. Since the substrate assembly 131 is divided and taken out as individual heating bodies, the individual substrates 131 can be easily attached to the portions indicated by the dotted line A, that is, the side edges of the long sides and short sides of the individual substrates 131. A kerf that can be divided into two is formed. The kerfs are formed in advance by a laser scribing method which is a conventional means for dividing a ceramic substrate or the like in the substrate forming step. That is, the laser beam is applied to the side edges of the individual substrates on the long side and the short side. Then, the substrate aggregate 131 is divided into individual heating bodies by utilizing the cut grooves.

[0006]

However, in the substrate 121 of the heating body formed by the above-mentioned manufacturing method, the substrate material melted by the heat of the laser beam is scattered on the side edge on the incident surface side of the laser beam. It is formed.

FIG. 14 is a partially enlarged side view of the heating body showing the flash in an enlarged manner and in the thickness direction. As shown in the figure, the flash 141 is formed so as to project in the incident direction of the laser beam.

Therefore, during the fixing operation, when the carrying sheet is moved by bringing it into contact with the surface of the heating element on which the resistance heating element 122 is formed, the carrying sheet is caught by the flash of the substrate 121 and is to be fixed. There are problems that the smooth transportation of the body is hindered and the transportation sheet is damaged.

In order to solve this problem, without using the laser scribing method, in the state of the soft green sheet before firing the substrate assembly, the concave groove for dividing into individual substrates is previously pressed. The present inventor tried an experiment for a method of forming by. However, since the general substrate material such as green sheet has the property of shrinking when fired, the lengthwise direction and the short side depend on the dimensions of the board determined by forming the groove before sintering and the dimensions of the board after firing. Differences occurred in both directions. Then, this dimensional difference remarkably occurred in the longitudinal direction of the substrate. Further, in order to solve this problem, it is difficult to predict the shrinkage amount of the substrate in advance and determine the position of the concave groove.

Separately from this, the above-mentioned Japanese Patent Laid-Open No. 2-65.
As described in Japanese Patent Application No. 086, a resistance heating element is formed on a surface opposite to a substrate surface on which a flash is formed by a laser scribing method, and this surface is used as a sliding heating surface, and the transfer sheet is caught by the flash. A heating element that prevents this is also known. However, this heating body has a problem that the substrate surface on which the laser scribing method is performed is different from the substrate surface on which the resistance heating element is formed, and thus the work of reversing the substrate is required in the manufacturing process, which complicates the manufacturing process. It was Also,
Some burrs were also generated when the substrate was cracked on the surface opposite to the surface on which the laser scribing method was performed.

An object of the present invention is to provide a heating body, a fixing device and an image forming apparatus which can eliminate the above problems by improving the method for forming the substrate of the heating body.

[0012]

According to the first aspect of the present invention,
A taper portion having an angle of 45 ° or more with respect to one surface is formed on at least a part of one side surface along the longitudinal direction, and at least one end surface is formed to have lower smoothness than the central portion of the one surface. And a resistance heating element attached to one surface of the substrate.

The reason for forming the angle of the tapered portion to be 45 ° or more with respect to one surface of the substrate is as follows.

For example, in the state of the green sheet before firing the substrate, when the taper portion is formed by pushing the pressing die to a certain depth in the thickness direction of the substrate having a flat surface, the green around the taper portion is formed. The sheet is compressed and the density of this part becomes high. When such a green sheet is sintered, the amount of shrinkage at the time of sintering differs between the compressed portion and the non-compressed portion, which may cause distortion inside the substrate and cause substrate cracking. If the taper portion having the same depth is formed, the angle of the taper portion is 45 ° or more with respect to one surface of the substrate, and the angle is 45 ° or more, the green sheet is compressed. The volume of the green sheet becomes small, and the volume of the high density portion of the green sheet can be made relatively small. Therefore, the boundary between the high density portion and the low density portion of the green sheet can be suppressed to a relatively small area, and the probability that the substrate will be damaged when the green sheet is sintered can be reduced.

Further, even if the taper portion has the same depth, the width of the substrate can be made narrower by setting the angle with respect to the one surface of the substrate to be 45 ° or more, and a thinner heating element can be constructed.

The angle of the taper portion is measured by the flat surface of the taper portion having the largest angle with respect to one surface of the substrate.

In the heating body described in the claims below, the substrate is preferably made of a ceramic material such as alumina, but other insulating materials may be used.

The resistance heating element is generally formed by using a resistance material such as a silver / palladium alloy-based material or a ruthenium oxide-based material by, for example, a screen printing method, but other materials may be used. You may provide using methods other than. The shape is not particularly limited.

Further, the end surface of the substrate means a side surface along the edge side direction of the substrate.

The side surface and the end surface of the electrically insulating substrate are
When the substrate is very thin, the side edge and the edge are the side surface and the edge surface, respectively.

The side surface and the end surface of the electrically insulating substrate are
For example, it may be covered with a glass film or the like.

According to a second aspect of the present invention, in the heating element according to the first aspect, the surface roughness of one surface of the substrate and the taper portion are substantially equal.

It should be noted that the above-mentioned approximately equality is ± 1.5 μm
Means a degree. The reason is as follows.
When a substrate is formed of a ceramic material such as alumina by using, for example, the doctor blade method, the surface roughness of the substrate surface is generally about 0.1 to 1.
It becomes 5 μm. If the tapered portion is formed by, for example, a pressing die, the surface roughness thereof can be set to be equal to or slightly larger than that of the substrate surface (Ra is about 0.1 to 3.0 μm).
Therefore, “substantially equivalent” is an expression for including the substrate manufactured by the above manufacturing method in the definition of the substrate of claim 2.

In the heating element according to claim 1 or 2, the tapered portion formed on the side surface of the substrate may be formed adjacent to only one surface side of the substrate or adjacent to both surface sides thereof. Good. Further, it may be formed individually on both side surfaces along the longitudinal direction of the substrate or may be formed on only one side surface.

Further, the taper portion does not have to be formed over the entire length of the side surface along the longitudinal direction of the substrate, and may be formed only at least on the portion where the fixing target or the transport sheet slides. .

The center of the plane is not limited to the central portion of one surface of the substrate, but means the entire surface of the substrate excluding the side edges.

According to a third aspect of the present invention, there is provided an electrically insulating elongated substrate in which at least one side face along the longitudinal direction is formed such that a portion on one side is smoother than a portion on the other side and at least one end face. , A resistance heating element attached to one surface of the substrate.

The portion of the side surface of the substrate on the one surface side is a portion formed adjacent to the one surface, and the portion of the substrate side surface on the other surface side is formed adjacent to the other surface. Means that.

The above-mentioned highly smooth side surface portion does not have to be formed over the entire length of the side surface along the longitudinal direction of the electrically insulating substrate, and at least the portion on which the body to be fixed or the transport sheet slides. It is sufficient if it is formed only on.

Further, in the heating body according to the first to third aspects, the end surface of the substrate may be formed in any way. For example, when cutting out from a substrate aggregate, a groove may be cut using a laser scribing method, or a cut surface when cutting using a sandblast may be an end surface.

According to a fourth aspect of the present invention, a part of at least one side surface along the longitudinal direction is formed in a mold, and at least one end surface is grooved and cut by a laser scribing method. And a resistance heating element attached to one surface.

The term "mold formation" means that the shape is processed by, for example, a pressing die in a soft state before the substrate is sintered.

The kerfs formed by the laser scribing method are not limited to those that are completely continuous, and include those in which a plurality of dot-shaped depressions are continuously provided. Irradiation with the laser beam may be performed from either side of the electrically insulating substrate.

In the case where only one side edge in the longitudinal direction is formed by molding, for example, this substrate is located at the outermost end of the substrate assembly, so that one side edge in the longitudinal direction is divided. There may be a case where it is not necessary to form a concave groove for.

According to a fifth aspect of the present invention, there is provided the heating element according to any one of the first to fourth aspects, a conveying sheet which can travel in a direction intersecting the longitudinal direction of the heating element, and a conveying sheet. The heating element is arranged so as to face the heating element via the sheet so as to be in pressure contact with the heating element, and heat from the heating element acts on the toner forming the image on the fixing object and the fixing object via the transport sheet. And a fixing roller for conveying the body.

According to a sixth aspect of the present invention, there is provided a means for adhering toner to an electrostatic latent image formed on a medium to form a reverse image and transferring the reverse image to a fixing member to form a predetermined image. The fixing device according to claim 5 is provided.

[0037]

The heating element according to any one of claims 1 to 4 is a fixing member such as a sheet or a conveying sheet for conveying the fixing member when a fixing operation is carried out by being incorporated in a fixing device.
It is pressed against the surface on the side where the resistance heating element is formed. At this time, the object to be fixed is heated by the heat generated by the heating element.

In the heating element according to the first aspect, the substrate has a part of at least one side surface along the longitudinal direction, which is 4 per surface.
A tapered portion having an angle of 5 ° or more is formed.
With a substrate having such side surfaces, the side surfaces along the longitudinal direction can be easily formed by, for example, forming a mold. Moreover, since the amount of contraction in the longitudinal direction during sintering of the substrate is large, the accuracy of the distance between the end faces is less smooth than the central portion of one face. With such a side surface, it can be formed by cutting out by a laser scribing method or the like, for example.

Therefore, if the above-mentioned forming method is used, the side surface in the longitudinal direction on which the body to be fixed slides becomes very smooth and the frictional resistance can be suppressed to a low level. Since the cutting is performed, it is possible to obtain the heating body in which the longitudinal dimension of the substrate can be accurately set.

Since the angle of the taper portion is formed to be 45 ° or more with respect to the one surface of the substrate, when the substrate is divided from the substrate aggregate at the taper portion, the division surface is relative to the one surface of the substrate. It becomes easier to form a right angle. Further, it is possible to make it difficult for the paper or the transport sheet to come into contact with the burrs formed on the edge portion of the taper portion located on the back surface side of the substrate when the substrate is divided from the substrate assembly.

When the heating element is manufactured by the above-mentioned manufacturing method, the direction in which the mold is pressed, the direction in which, for example, a laser beam is applied for cutting out, and the direction in which the resistance heating element is printed are the same. Therefore, it is not necessary to invert the substrate in the heating body forming step.

The heating element according to claim 2 has the same action as the heating element according to claim 1.

According to the third aspect of the present invention, in the substrate, at least one side face along the longitudinal direction is formed such that a portion on one surface side is higher in smoothness than a portion on the other surface side and at least one end surface. With such a substrate, the side surfaces along the longitudinal direction can be easily formed by, for example, molding. In addition, the end face, which is difficult to obtain the accuracy of the distance between both sides due to a large contraction amount in the longitudinal direction during sintering of the substrate, can be formed by cutting out by, for example, a laser scribing method.

Therefore, when the above-mentioned forming method is used, the side surface in the longitudinal direction on which the body to be fixed slides becomes very smooth and the frictional resistance is suppressed to a low level. It is possible to obtain a heating element whose dimensions can be set accurately.

When the heating element is manufactured by the above manufacturing method, the direction in which the mold is pressed, the direction in which, for example, a laser beam is irradiated for cutting by the method and the direction in which the resistance heating element is printed are the same. It is not necessary to invert the substrate in the heating body forming step.

In the heating element according to the fourth aspect, since the substrate has a part of at least one side surface along the longitudinal direction in which the object to be fixed slides, this part has a very high smoothness. Can be formed. Further, since at the time of sintering the substrate, the amount of contraction in the longitudinal direction is large, it is possible to cut at least one of the end faces where it is difficult to obtain the accuracy of the interval by laser scribing after the substrate is sintered.

Therefore, the side edges of the sliding surface of the substrate, which are formed in the longitudinal direction, have a very smooth surface, and the frictional resistance with the object to be fixed or the sheet for conveyance can be kept low, and at the same time, It is possible to obtain a heating body in which the longitudinal dimension of the substrate can be accurately set.

When the heating element is manufactured by the above manufacturing method, the direction in which the mold is pressed, the direction in which the laser beam is applied for cutting by the method, and the direction in which the resistance heating element is printed are the same. There is no need to invert the substrate in the heating body forming process.

According to a fifth aspect of the present invention, in the fixing device, a fixed body on which a predetermined image is formed with toner is inserted between the heating body and the fixing roller according to any one of the first to fourth aspects. By the rotation of the fixing roller, the member to be fixed travels between the heating member and the fixing roller together with the sheet for conveyance. Then, the heat generated by the heating body acts on the toner forming the image of the fixing target through the transport sheet, and the toner is fixed to the fixing target.

At this time, the object to be fixed or the sheet for conveyance can be smoothly conveyed by the heating element according to any one of claims 1 to 4.

In the image forming apparatus according to the sixth aspect, toner is attached to the electrostatic latent image formed on the medium to form a reverse image, and the reverse image is transferred to form a predetermined image on the fixing body. To do. Then, the toner attached to the fixing target is fixed by the fixing device according to the fifth aspect. At this time, a clear image can be formed by the action of the fixing device according to the fifth aspect.

[0052]

EXAMPLES Examples of the heating element of the present invention will be described below with reference to FIGS. 1 is a partially cutaway front view showing a first embodiment of a heating element of the present invention, FIG. 2 is a partially cutaway rear view, and FIG. 3 is an enlarged cross-sectional view taken along the line AA in FIG. FIG. 4 and FIG. 4 are side views of the same side. In addition,
3 and 4 show the heating element partially enlarged in the thickness direction, and the burr is enlarged and schematically shown in the drawing.

In these figures, reference numeral 1 denotes a length of about 300 mm, a width of about 10 mm, and a thickness of 0.65 made of an electrically insulating material such as alumina ceramics (A1203).
It is a 1 mm elongated substrate. As shown in FIGS. 3 and 4, this substrate 1 has a tapered portion 11a formed of an inclined surface on the side surface along the longitudinal direction on the one surface 11 side. Further, a flash 13 is present on the end surface of the substrate 1 on the one surface 11 side over the entire side edge. The surface of the tapered portion 11a may have some undulations that occur when the substrate 1 is sintered.

Reference numeral 2 indicates a length of about 230 mm, a width of about 2 mm, and a thickness of about 1 formed along the longitudinal direction on one surface 11 side of the substrate 1.
It is a strip-shaped resistance heating element mainly composed of 0 μm silver / palladium (Ag / Pd) alloy. 3 and 3 have a length of about 15 mm formed by laminating at both ends of the resistance heating element 2,
The terminal portion for power supply is made of a good conductive material mainly composed of a wide silver-palladium (Ag.Pd) alloy having a width of about 6 mm.

Reference numeral 4 denotes a thickness of about 2 made of a glass material or the like formed so as to cover almost the entire area of the one surface 11 side of the substrate 1 including the resistance heating element 2 except for the terminals 3 and 3 and a part of the substrate 1.
It is an electric insulation coating layer of 0 to 100 μm.

61 and 62 are formed in parallel with each other on the other surface 12 side of the substrate 1 along the extending direction of the resistance heating element 2 and are similar to the terminals 3 and 3 in a silver-palladium (Ag.Pd) alloy. A pair of wiring conductors mainly having a width of about 1 mm and a film thickness of about 10 to 30 μm. 63 and 64 are wiring conductors 61 and 6
2 is a wide temperature detection terminal integrally formed at both ends.

Reference numeral 6 is a temperature detecting element such as a thermistor for electrically connecting the other ends of the wiring conductors 61 and 62.
The temperature detection element 6 detects the heat generation temperature of the resistance heating element 2 and is electrically connected to a temperature control circuit (not shown) via the wiring conductors 61, 62 and 63, 64 temperature detection terminals to connect the resistance heating element 2 to the temperature control circuit. It has a mechanism to control the temperature.

Next, a method of manufacturing the heating element will be described with reference to FIGS.

FIG. 5 is a simplified diagram showing an apparatus for forming the substrate 1 by the doctor blade method, for example. The process of forming the substrate 1 will be described. First, kneading was performed by adding fine particles of alumina (Al203) as a raw material of the substrate 1 to polyvinyl butyral as a binder, polyethylene glycol and octyl phthalate as a plasticizer, menhaden oil as a peptizer, and trichloroethylene and ethyl alcohol as a solvent. And make paste 51.

Next, the paste 51 is transferred to a funnel-shaped container 52, and the paste 51 flowing out of the container 52 is extruded from between a base 53 and a blade 54 fixed at a predetermined interval t to a predetermined position. A continuous alumina green sheet 55 having a thickness t is formed. The continuously formed green sheet 55 has a plurality of elongated convex portions 56, 56, ... At predetermined intervals (equal to the width of the substrate 1).
A press type pressing die 57 that moves in the direction of the middle arrow is pressed to form the concave grooves 7, 7, ... On the upper surface of the green sheet 55.

FIG. 6 is a partially enlarged sectional view of the green sheet showing the shape of the groove 7. The groove 7 is formed in a V shape as shown in the drawing, and the opening angle of the V shape is 15
About 30 degrees, the depth is 1 / thickness of the green sheet 55
It is about 3 to 1/2. With this setting, the substrate assembly after sintering of the green sheet is less likely to be inadvertently cracked for each substrate of the individual heating bodies, and the substrate assembly can be easily handled. Easy to divide into substrates.

When it is necessary to form a through hole in the substrate, it is possible to form a groove and a through hole in the green sheet at the same time by using a pressing die having a projection for forming the through hole.

The concave grooves 7, 7, ... May be continuously formed by using a roller-type pressing die that rotates in response to the flow of the continuously formed alumina green sheet 55. .

FIG. 7 is a partially cutaway perspective view showing a substrate assembly 71 in which the above-described green sheet 55 is sintered at a predetermined temperature for a predetermined time in a heating furnace and a resistance heating element and the like are further formed. . In order to set the substrate length to 300 mm, for example, before forming the resistance heating element, the substrate assembly 71 has a kerf formed by laser scribing from the one surface 11 side of the substrate 1 to a portion indicated by the CC line. As a result, the kerf and the concave grooves 7, 7, ... Enclose the resistance heating element 2 formed in a later step, that is, the kerf and the concave grooves 7, 7 ,. The body dimensions are set. The substrate assembly 71 is further divided in the subsequent steps at the concave grooves 7, 7, ..., Thus, the substrate 1 of each heating body is obtained.

The resistance heating element 2 is, for example, a silver-palladium alloy (Ag / Pd) or ruthenium oxide (Ru02).
It is formed by a resistance paste obtained by kneading a powder of a conductive material such as, for example, frit glass (inorganic binder), an organic binder and the like. Then, the resistance paste is applied to the substrate assembly 71.
Between the concave grooves 7, 7 on the one surface 11 side, that is, on the substrates 1, 1, ... of each heating body by a screen printing method, and after drying, baking is performed at about 850 ° C. for about 10 minutes. It is fixed to the aggregate 71.

The terminal portions 3 and 3, the wiring conductors 61 and 62, and the temperature detection terminals 63 and 64 are made of a conductive paste having a smaller electric resistance than the resistance paste at a predetermined position on one surface or the other surface of the substrate assembly 71. It is formed by applying it by a printing method and then firing it. This conductive paste is a silver / palladium alloy (Ag / Pd), silver (Ag), silver / platinum alloy (Ag / Pt), gold (Au), platinum having a smaller palladium content than the above resistance paste. A conductive material having a low resistance such as (Pt) is used.

The electrically insulating coating layer 4 (not shown) is
For example, it is formed by applying a glass paste containing lead borosilicate glass as a main component to a predetermined portion on the one surface 11 side of the substrate assembly 71 by a screen printing method, and then firing it.

Similarly, the thermistor 6 (not shown)
A conductive adhesive is printed and applied to one end of each of the wiring conductors 61 and 62 on the other surface of the substrate assembly 71, and the wiring conductors 61 and 62 are placed on the conductive adhesive in correspondence with the electrodes. It Then, this conductive adhesive is heated and solidified, and the thermistor 6 is fixed to the substrate assembly 71.

Then, the kerf (C
-C dotted line) and a force is applied to the substrate assembly 71 so that the most force is applied to the recessed grooves 7, 7, ..., And the substrate assembly is performed at the cut grooves and the recessed grooves 7, 7 ,. Body 71
To obtain individual heating elements.

The heating element manufactured as described above is the substrate 1
The tapered portion 11 is formed on the side surface along the longitudinal direction on the one surface 11 side.
a is formed. The tapered portion 11a is a part of the inner surface of the V-shaped concave grooves 7, 7, .... This taper part 11a
The surface of the corner portion 8 located on the one surface 11 side of the substrate 1 has a higher smoothness than that of the corner portion 15 located on the other surface 12 side because the mold is formed as described above. In addition, the surface of the tapered portion 11a is similarly shaped, so that the substrate 1
The smoothness is higher than that of the side surface located on the other surface 12 side. The side surface located on the side of the other surface 12 has a burr 14 formed when the substrate 1 is broken. However, since it is difficult for the carrying sheet to come into contact with the burr 14, the fixing operation is greatly hindered. Not like that.

Further, as shown in FIG. 4, the end face of the substrate 1 has a flash 13 made of the substrate material (ceramic fine powder residue) which is melted and scattered on the side 11 where the laser beam is incident.
Is formed.

When the end face of the substrate 1 is cut, the laser beam may be irradiated from the other surface side. In this case, the burr 13 is formed on the other surface side of the substrate.

FIG. 8 is an enlarged sectional view in the end face direction showing a second embodiment of the heating element of the present invention. In addition, the same drawing shows the heating body in an enlarged manner particularly in the thickness direction. This heating body has almost the same structure as the heating body of the first embodiment, but a tapered portion 82 is formed on the entire side surface in the thickness direction of the substrate 81 on the side surface along the longitudinal direction.

The surface of the corner portion 84 of the taper portion 82 located on the one surface 83 side of the substrate 81 has a relatively high smoothness because it is formed in the same manner as in the first embodiment and is located on the insertion side of the die. . On the other hand, the corner portion 86 located on the other surface 85 side is lower in smoothness than the corner portion 84 on the insertion side because it is located on the insertion side of the mold. It should be noted that the corner portion 86 located on the delivery side does not greatly hinder the fixing operation because the object to be fixed and the conveying sheet are hard to contact even if the smoothness is somewhat low.

In this method for manufacturing a heating element, the side edges in the longitudinal direction of the individual substrates of the green sheet are completely divided by, for example, a pressing die without forming a groove on the upper surface of the green sheet. This is different from the method for manufacturing the heating element of the first embodiment.

FIG. 9 shows a circuit configuration for controlling the amount of heat generated by these heating elements. In the figure, a broken line frame indicated by 91 is a heating element, 92 is a resistance heating element, 93 and 93 are terminals, and 96 is a thermistor. Also, S is a commercial power source,
T indicates a temperature control circuit. When electricity is applied between the terminals 93 and 93 of the heating element 91 via an SSR (solid state relay) connected to the control terminal of the temperature control circuit, a current flows through the resistance heating element 92 to generate heat. The heat generation temperature of the resistance heating element 92 is conducted to the thermistor 96 and changes the resistance value of the heat sensitive element in the thermistor 96. The temperature control circuit T detects this change in resistance value and determines whether the resistance heating element 92 is in a desired temperature range. When the detected temperature is lower than the desired temperature, the temperature control circuit outputs an ON signal to the SSR to energize the resistance heating element 92. If the detected temperature is higher than the desired temperature, an OFF signal is output to the SSR to cut off the power supply to the resistance heating element 92.

In this way, the resistance heating element 92 is controlled in temperature by controlling the electric power applied to the resistance heating element 92.
The temperature control circuit T has been described in the case of performing ON / OFF control by SSR, but in addition, PWM (Puls
The ON / OFF control may be performed by e Width Modulation (pulse width control method) or the like.

FIG. 10 is a sectional view showing an embodiment of the fixing device according to the present invention. In the figure, 101 is a cylindrical fixing roller, the outer surface of which is covered with a heat resistant elastic material such as silicon rubber (not shown). Reference numeral 102 denotes, for example, the heating element of the above-described embodiment, which is arranged so that the resistance heating element 103 faces the pressure roller 101 and is in pressure contact with the fixing roller 101. A conveying sheet 104 is sandwiched between the pressure roller 101 and the heating body 102, and travels in a direction perpendicular to the longitudinal direction of the heating body 102. The carrying sheet 104 is formed of a heat resistant resin such as a polyimide resin into a tubular shape.

In this fixing device, a connector (not shown) electrically connected to a power source and a heat generation control circuit is provided with a heating element 10.
2 is connected to a predetermined terminal to energize the heating element 102. Then, the sheet 105 on which a predetermined image is formed with toner is inserted between the heating body 102 and the fixing roller 101, so that the sheet 105 is rotated by the fixing roller 101 and the heating sheet 102 and the fixing roller together with the conveying sheet 104. It runs between 101. At this time, the heating element 1
The heat generated in 02 passes through the sheet 104 for conveyance to the sheet 1
The toner acts on the toner forming the image No. 05, and the toner is fixed on the paper. The resistance heating element 103 is formed with a length equal to or larger than the width of the paper 105 used, and can heat the paper 106 substantially uniformly in the extending direction.

FIG. 11 is a schematic sectional view showing an embodiment of the image forming apparatus of the present invention. The figure shows a copying machine as an example of the image forming apparatus. In the figure, 111 is a casing of the copying machine, and 112 is an original placing table provided on the upper surface of the casing 111 and made of a transparent member such as glass. A lamp 113 is provided above the inside of the housing 111.
The light rays reflected from the original 114 irradiated by the light source 13 are reflected by the short-focus small-diameter image forming element array 115 and
Slit exposed on top. The photosensitive drum 116 has, for example, a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer formed on its surface, and rotates in the direction of the arrow. 117 is a charger,
The electrostatic latent image is formed by uniformly charging the zinc oxide photosensitive layer or the organic semiconductor photosensitive layer on the surface of the photosensitive drum 116. A developing device 118 forms a toner image by attaching a toner to the electrostatic latent image.

On the other hand, the paper 120 stored in the cassette 119 is fed to the photosensitive drum 1 by the feeding roller 121.
16 sent up. Then, the toner image formed on the photosensitive drum 116 is transferred onto the sheet 120.

After this, the paper 11 separated from the drum P4
The sheet 9 is further conveyed and guided to the above-described fixing device to fix the toner image on the sheet 120, and then discharged onto the tray 122.

Note that it is not always necessary to form a taper portion on the side surface along the longitudinal direction of the substrate, and even when the side surface perpendicular to one surface of the substrate is formed by a pressing die to be a smooth surface, the sheet for conveyance or the object to be covered is formed. The fixing member can be conveyed relatively smoothly.

The method of forming the green sheet from the ceramic material is not limited to the doctor blade method, but may be, for example, a method of stretching the ceramic material using a roller or a method of pushing the ceramic material using a pressing die. It is also possible to individually form the substrates for each heating body without forming.

A resistance heating element may be formed before grooving the substrate assembly by the laser scribing method. Alternatively, the substrate assembly may be divided in advance into substrates for individual heating elements, and then a resistance heating element may be applied to form the substrate.

The conductive material forming the resistance heating element and the terminal is made of the silver-palladium alloy (Ag.P) of the above embodiment.
It is needless to say that the material is not limited to the d) type and may be a PTC (positive temperature characteristic element) or the like, and is appropriately selected according to the heat generation temperature and the condition of the heater used. Further, the resistance heating element is not limited to one, and a plurality of resistance heating elements may be formed.

In the above embodiment, the wiring conductor is formed on the back side of the substrate and the temperature detecting element such as the thermistor is fixed to the wiring conductor. However, the wiring conductor and the temperature detecting element are not essential. It goes without saying that the present invention can be applied to a heating body that does not have these.

Further, the image forming apparatus of the present invention is not limited to a copying machine, but extends to all apparatuses such as facsimiles and printers that form an image using toner.

[0089]

According to the first aspect of the present invention, the side faces in the longitudinal direction can be easily formed, for example, by molding, and the end faces can be easily formed by cutting out by, for example, the laser scribing method. It is possible to easily provide a heating body which can suppress the frictional resistance relatively low and at the same time can accurately set the dimension of the substrate in the longitudinal direction.

According to the invention described in claim 2, it is possible to provide a heating body having the effect of the heating body according to claim 1.

According to the invention described in claim 3, it is possible to provide a heating body having the effect of the heating body according to claim 1.

According to the fourth aspect of the present invention, since the side surface of the conveying sheet in contact with the longitudinal direction has high smoothness, the frictional resistance between the sheet to be fixed and the conveying sheet can be kept relatively low. Further, since at least one of the end faces is cut by grooving by the laser scribing method, it is possible to provide a heating body capable of accurately setting the longitudinal dimension of the substrate.

According to the invention of claim 5, by the effect of the heating element according to any one of claims 1 to 4,
It is possible to provide a fixing device that can smoothly convey an object to be fixed or a sheet for conveyance and that can store a heating element with high accuracy.

According to the sixth aspect of the invention, the effect of the fixing device according to the fifth aspect can provide an image forming apparatus capable of forming a clear image.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view showing a first embodiment of a heating body of the present invention.

FIG. 2 is a partially cutaway rear view of the same.

FIG. 3 is an enlarged cross-sectional view taken along the line AA of FIG.

FIG. 4 is an enlarged side view of the heating element shown in FIG. 1 in the short side direction.

FIG. 5 is a simplified diagram showing an apparatus for forming a substrate 1 by a doctor blade method.

FIG. 6 is a partially enlarged cross-sectional view showing a green sheet in one manufacturing process of the heating body of the present invention.

FIG. 7 is a partially cutaway perspective view showing a substrate assembly in one manufacturing process of the heating body of the present invention.

FIG. 8 is an enlarged side view in the short knitting direction showing a second embodiment of the heating element of the present invention.

FIG. 9 is a circuit diagram showing an example of a circuit for controlling the amount of heat generated by the heating element of the present invention.

FIG. 10 is a sectional view showing an embodiment of a fixing device of the present invention.

FIG. 11 is a schematic sectional view showing an embodiment of the image forming apparatus of the present invention.

FIG. 12 is a partially cutaway front view showing a conventional heating body.

FIG. 13 is a partially cutaway perspective view showing a substrate assembly in one manufacturing process of a conventional heating body.

14 is a partially enlarged side view of the heating element of FIG.

[Explanation of symbols]

1, 81 ... Substrate, 2 ... Resistance heating element, 7 ...
・ Concave groove, 8, 15, 84, 86 ... Corner, 71 ...
・ Substrate assembly, 11a ... Tapered portion, 13 ...
Flash, 101 ... Pressure roller, 102 ... Heating body, 104 ... Conveying sheet

Claims (6)

[Claims] 1. A taper portion having an angle of 45 ° or more with respect to one surface is formed on a part of at least one side surface along the longitudinal direction, and at least one end surface is formed to have lower smoothness than a central surface portion of the one surface. And a resistance heating element that is attached to one surface of the substrate. 2. The heating element according to claim 1, wherein the surface roughness of the one surface of the substrate and the taper portion of the one surface are substantially equal to each other. 3. An elongated substrate having an electrically insulating edge, in which at least one side surface along the longitudinal direction, a portion on one surface side is formed to be smoother than a portion on the other surface side and at least one end surface; And a resistance heating element applied to the heating element. 4. An electrically insulating elongated substrate having a part of at least one side surface along the longitudinal direction formed by molding, and at least one end surface of which is cut by grooving by a laser scribing method; A resistance heating element; and a heating element. 5. The heating element according to claim 1, a transport sheet capable of traveling in a direction intersecting a longitudinal direction of the heating element, and a heating element via the transport sheet. A fixing roller which is arranged so as to face the heating member under pressure and causes heat from the heating member to act on the toner forming the image of the fixing target through the transport sheet and also conveys the fixing target. And a fixing device. 6. A means for adhering toner to an electrostatic latent image formed on a medium to form a reversal image, and transferring the reversal image to a fixing member to form a predetermined image. An image forming apparatus comprising: the fixing device described above.