JPH11282304A - Fixing apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To restrain the occurrence of the unevenness in temperature in a fixing apparatus in which the pattern of a resistance exothermic body of an exothermic body sheet is formed by a plurality of meandering patterns arranged so that partially folded bent parts are opposed to each other and the fixing of a recording material is carried out by the heating of the meandering pattern. SOLUTION: In an exothermic part 5e, meandering patterns 5c1 to 5c9 are formed front a feed part 5a toward the center successively by four rows. The folded bent parts 5d being opposed to each other of the respective meandering patterns 5c are formed in nearly V-shapes 5d1, 5d2 instrument into a pair of folded bent parts arranged oppositely, or in a circular-arc shapes 5d3, 5d4 arranged alternately over the entire circumferential direction, or in nearly rectangular shapes 5d5 to 5d9 having an opposite side extending in the direction perpendicular to the opposite direction of the respective folded bent parts 5d to the outside. Thus, the respective folded bent parts 5d being opposite to each other can be brought to near without impairing insulation.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is used in an image forming apparatus for forming an image by attaching a recording material to a recording medium such as paper, and fixing the recording material adhered to the recording medium. About.

[0002]

2. Description of the Related Art Conventionally, there has been known an image forming apparatus provided with an image forming means for forming an image by adhering a recording material such as toner or ink to a recording medium such as paper or film.
Many of these types of image forming apparatuses include a fixing device that fixes a recording material adhered to a recording medium by the image forming unit. As this type of fixing device, a fixing heating roller for heating a recording material adhered to a recording medium,
There is a fixing roller provided with a pressing roller for pressing the recording medium on the outer peripheral surface of the fixing heating roller. In the fixing device configured as described above, the recording medium after image formation is conveyed while being sandwiched between the fixing heating roller and the pressing roller, and the recording material is heated and pressed together with the recording medium, and the recording material is recorded. It can be fixed on a medium.

[0003] The configuration of the fixing heat roller is as follows.
Conventionally, there has been considered a configuration in which a halogen lamp is built in, and the heat generated by the halogen lamp is conducted to the roller surface to raise the temperature of the entire fixing heating roller. However, since the halogen lamp of such a heating roller for fixing is usually disposed near the rotation axis of the roller, the heat efficiency is poor, and the surface of the heating roller for fixing is fixed after the energization of the halogen lamp is started. It took a long time to raise the temperature to a suitable temperature.

Therefore, in recent years, various studies have been made on the heat roller for fixing in order to increase the thermal efficiency and the temperature rising speed. For example, an insulating film material in which a roller body is formed in a cylindrical shape and a pattern of a resistance heating element is formed on the inner surface side along an inner peripheral surface thereof (hereinafter, the entirety including the pattern is referred to as a heating element sheet) is used. It is considered to be arranged. In this case, the roller body is often made of a metal having good thermal conductivity, but the pattern and the roller body are insulated from each other by an insulating film material. Therefore, when the pattern is energized to generate heat, heat is conducted from the vicinity of the inner peripheral surface of the roller body, and the thermal efficiency and the temperature rising rate can be improved satisfactorily.

[0005] This type of pattern is generally formed in a meandering pattern having an arc-shaped bent portion.
When forming a large pattern, a plurality of meandering patterns are formed by arranging vertically and horizontally. In this case, the plurality of meandering patterns are arranged such that the bent portions are partially opposed to each other.

[0006]

However, when a plurality of meandering patterns are arranged with their bent portions facing one to one, the bent portions cannot be arranged very close to each other in order to ensure insulation between the meandering patterns. For this reason, the amount of heat conducted from the pattern is reduced at a portion sandwiched between the pair of bent portions facing each other, so that there is a possibility that the temperature of the surface of the fixing heat roller becomes uneven. In this case, the fixing of the recording material also becomes uneven.

For example, as shown in FIG. 5, in a heating element sheet in which eight meandering patterns 95c are formed in 2 rows × 4 rows, a position Q sandwiched between opposed bent portions 95d.
Therefore, the amount of heat provided for fixing the recording material is reduced. Therefore, the present invention forms the pattern of the resistance heating element of the heating element sheet with a plurality of meandering patterns arranged with a part thereof being bent and facing each other, and fixing the recording material by the heat generation of the meandering pattern. The purpose of the present invention is to suppress the occurrence of temperature unevenness in the fixing device.

[0008]

Means for Solving the Problems and Effects of the Invention According to the first aspect of the present invention, there is provided a fixing heating roller for heating a recording material adhered to a recording medium;
A pressing roller for pressing the recording medium on the outer peripheral surface of the fixing heating roller, wherein the recording medium is transported while being sandwiched between the fixing heating roller and the pressing roller, and the recording material adheres to the recording medium. Wherein the fixing heating roller is configured to supply current to a cylindrical roller body and an insulating film material disposed along the inner or outer peripheral surface of the roller body. And a heating element sheet formed by forming a pattern of a resistance heating element that generates heat in response thereto, and the pattern of the resistance heating element is formed of a plurality of meandering patterns arranged with bent portions facing each other, and The bent portions facing each other are alternately arranged over the entire circumferential direction.

In the present invention having the above-described structure, the pattern of the resistance heating elements of the heating element sheet provided on the fixing heating roller is formed by a plurality of meandering patterns arranged with their bent portions facing each other. The bent portions facing each other are alternately arranged over the entire circumferential direction. That is, in the opposing portion of the meandering pattern, the bent portions of each meandering pattern are arranged alternately (in a so-called zigzag shape), and are arranged over the entire circumference.

Therefore, even if the bent portions are brought closer to each other in the opposite direction, insulation between the meandering patterns can be ensured, and the pattern density in the opposite portion can be increased. Therefore, according to the present invention, the amount of heat transmitted from the pattern can be made uniform, and the occurrence of temperature unevenness can be favorably suppressed.

According to a second aspect of the present invention, there is provided a fixing heating roller for heating a recording material adhered to a recording medium, and a pressing roller for pressing the recording medium against an outer peripheral surface of the fixing heating roller. A fixing device for fixing the recording material adhered to the recording medium by transporting the recording medium while sandwiching the recording medium between the fixing heating roller and the pressing roller, wherein the fixing heating roller is formed in a cylindrical shape. A roller body, and a heating element sheet formed by forming a pattern of a resistance heating element that generates heat in accordance with energization on an insulating film material disposed along the inner peripheral surface or the outer peripheral surface of the roller main body. The pattern of the resistance heating element is formed of a plurality of meandering patterns arranged with the bent portions facing each other, and the bent portions facing each other are formed of a pair of bent portions facing each other. It is characterized in that it is formed into a substantially V-shape entering into.

In the present invention having the above-described structure, the pattern of the resistance heating elements of the heating element sheet provided on the fixing heating roller is formed of a plurality of meandering patterns arranged with the bent portions facing each other. The bent portions facing each other are formed in a substantially V-shape that enters between a pair of bent portions disposed to face each other.

Therefore, even if the bent portions formed in a substantially V-shape are brought close to each other in the above-mentioned opposite direction, the insulation between the meandering patterns can be ensured. Can be increased. Therefore, according to the present invention, the amount of heat transmitted from the pattern can be made uniform, and the occurrence of temperature unevenness can be favorably suppressed.

In the present invention, the bent portion formed in a substantially V-shape is formed so as to enter between a pair of bent portions opposed to each other.
Compared with the invention described above, the density of the pattern in the opposing portion can be further increased, and the occurrence of temperature unevenness can be more favorably suppressed. In addition, since the density of the pattern can be easily increased, the meandering pattern can be applied to a heating element sheet having a high density and a large calorific value as a whole. Can be suppressed.

According to a third aspect of the present invention, there is provided a fixing heating roller for heating a recording material adhered to a recording medium, and a pressing roller for pressing the recording medium on an outer peripheral surface of the fixing heating roller. A fixing device for fixing the recording material adhered to the recording medium by transporting the recording medium while sandwiching the recording medium between the fixing heating roller and the pressing roller, wherein the fixing heating roller is formed in a cylindrical shape. A roller body, and a heating element sheet formed by forming a pattern of a resistance heating element that generates heat in accordance with energization on an insulating film material disposed along the inner peripheral surface or the outer peripheral surface of the roller main body. A pattern in which the pattern of the resistance heating element is formed by a plurality of meandering patterns arranged with the bent portions facing each other, and the bent portions facing each other extend in a direction orthogonal to the facing direction. It is characterized in that it is formed in a substantially rectangular having sides outward.

In the present invention having the above-described structure, the pattern of the resistance heating elements of the heating element sheet provided on the fixing heating roller is formed by a plurality of meandering patterns arranged with their bent portions facing each other. The bent portions opposed to each other are formed in a substantially rectangular shape having outside facing sides extending in a direction perpendicular to the facing direction.

Therefore, even if the opposing sides of the bent portion are brought close to each other, insulation between the meandering patterns can be ensured, and the pattern density in the opposing portion of the bent portion can be increased. Therefore,
According to the present invention, the amount of heat transmitted from the pattern can be made uniform, and the occurrence of uneven temperature can be favorably suppressed.

Further, according to the present invention, the insulation between the meandering patterns can be similarly secured regardless of whether or not the opposite sides are alternately arranged. For this reason, between a plurality of meandering patterns arranged with the bent portions facing each other,
The present invention can be applied favorably even when the number of the opposing bent portions is different from each other.

According to a fourth aspect of the present invention, in addition to the configuration of the third aspect, the distance between the opposite sides of the bent portions facing each other can obtain a desired temperature distribution on the outer peripheral surface of the fixing heating roller. As described above, different intervals are set in each part. As described above, the opposing sides in the third aspect of the invention extend in a direction orthogonal to the opposing direction of the bent portion. Therefore, the temperature distribution on the outer peripheral surface of the heating roller for fixing can be easily changed by adjusting the interval between the opposed sides.
Therefore, in the present invention, the intervals between the opposed sides are set to different intervals in each part so that a desired temperature distribution can be obtained on the outer peripheral surface of the fixing heat roller.

Therefore, in the present invention, in addition to the effect of the third aspect of the invention, the amount of heat provided for fixing the recording material can be adjusted as desired in each section, so that the fixing can be performed more favorably. Such an effect is produced. For example, at both ends in the axial direction of the fixing heat roller, the amount of heat radiation tends to be large and the temperature tends to be lower than that at the center. However, such a difference in the amount of heat radiation is canceled out, and the temperature distribution is made more uniform. be able to.

The invention according to claim 5 is the invention according to claim 3 or 4.
In addition to the configuration described above, a part of the bent portion of the meandering pattern facing each other is formed in a substantially arc shape or a substantially V shape so that a desired temperature distribution is obtained on the outer peripheral surface of the fixing heat roller. It is characterized by being staggered.

According to the third or fourth aspect of the present invention, when a part of the bent portions facing each other in the meandering pattern is formed in a substantially arc shape or a substantially V shape and arranged alternately, the pattern density in that portion is reduced. It can be further increased. Therefore, in the present invention, a part of the bent portions facing each other is formed in a substantially arc shape or a substantially V shape so as to obtain a desired temperature distribution on the outer peripheral surface of the fixing heating roller, and is arranged alternately. ing.

Therefore, in the present invention, in addition to the effect of the third or fourth aspect, the amount of heat provided for fixing the recording material is adjusted as desired in each section, and the above-mentioned fixing is performed more favorably. The effect that it can do is produced. For example,
At both ends in the axial direction of the heating roller for fixing, the amount of heat radiation tends to be large and the temperature tends to be lower than that at the center, but such a difference in the amount of heat radiation can be offset to make the temperature distribution more uniform. it can.

[0024]

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view illustrating a configuration of an electrophotographic printer P (corresponding to an image forming apparatus) configured using the fixing device of the present invention. This printer P is a laser printer that performs exposure using a laser. First, the configuration of the printer P will be briefly described with reference to FIG.

The printer P includes a paper feed cassette section A in which sheets as recording media are stacked and stored, a manual paper feed section B capable of sucking sheets one by one, and a paper feed cassette section A or a manual paper feed section. A sheet conveying section C for conveying the sheet sucked from the section B, a drum-type electrophotographic photosensitive member, a charger, a developing device,
An electrophotographic process unit D (corresponding to an image forming unit), which includes a static eliminator and the like, and forms an image by attaching toner as a recording material to the conveyed paper, and modulates the charged photoconductor according to image data. A laser beam scanner S (exposure device) that scans and exposes the laser beam thus formed to form an electrostatic latent image on the photoconductor, a heating roller for fixing, a pressing roller, and the like. And a paper discharge unit F that conveys the paper on which the toner is fixed to a tray at the upper part of the main body.

FIG. 2 shows the fixing unit 5 disposed in the heat fixing unit E.
FIG. 2 is a cross-sectional view illustrating the configuration of FIG. The fixing device 51 includes a fixing heating roller (hereinafter, simply referred to as a heating roller) 1 for heating the toner attached to the sheet, and heat-resistant silicon rubber or the like provided around a metal shaft 53a. A pressing roller 53 for pressing the sheet against the outer peripheral surface, discharge rollers 55 and 57 for discharging the sheet to the outside of the apparatus, sheet guides 59 and 61 for guiding the sheet to a predetermined position, and covering the heating roller 1 and the pressing roller 53. A cover 63 and the like are provided. The heating roller 1 having the characteristic configuration of the present invention provides heat for fixing the toner to the sheet in the fixing device 51, and the discharge roller 55, with the sheet sandwiched between the heating roller 1 and the pressing roller 53. It also plays the role of transporting in the 57 directions.

Next, the heating roller 1 will be described in detail. FIG. 3 is a cross-sectional view illustrating a configuration in which the fixing device 51 is cut along the rotation axis of the heating roller 1. This heating roller 1
Has a hollow cylindrical roller body 3 made of aluminum, and a heating element sheet 7 provided with a resistance heating element pattern 5 that generates heat in accordance with energization on an inner peripheral surface of the roller body 3, A sponge tube 9 made of a silicon sponge as a material is sequentially arranged.
A pair of bearings 11 is fitted and fixed to the outer peripheral surface of the roller body 3 near both ends, and a spur gear 13 is fitted and fixed to one outer side.

Here, the pair of bearings 11 are made conductive by dispersing carbon in PPS (polyphenylene sulfide) having excellent heat resistance.
Is rotatably supported by a heat-resistant resin frame 67 together with the metal shaft 53a. The roller body 3 is grounded via the bearing 11, and the pressing roller 53 is grounded via the metal shaft 53a. For this reason, it is possible to prevent the charged toner and the like from adhering to the heating roller 1 or the pressing roller 53 and also to prevent the occurrence of noise and the like.

Further, a rotational force is transmitted to the spur gear 13 from a drive system (not shown), whereby the roller body 3 can be rotated to convey the paper. Further, a portion of the outer peripheral surface of the roller body 3 that is in pressure contact with the pressing roller 53 is
Coating treatment with fluororesin which is excellent in heat resistance and releasability is performed.

Next, FIG. 4 is a plan view showing the structure of the heating element sheet 7. In FIG. 4, a dashed line C represents the center line of the heating element sheet 7, and the heating element sheet 7 is configured substantially symmetrically with respect to the dashed line C. As shown in FIG. 4, the heating element sheet 7 includes an insulating film material 17 formed by stacking two polyimide films having an insulation property of 3 KV withstand voltage, and a stainless steel (SUS) on the surface thereof.
The pattern 5 is formed by sticking a thin film of the above and performing an etching process. The insulating film material 17 is formed in a rectangular sheet shape, and its long side has the same length as the roller body 3 and its short side has almost the same length as the inner circumference of the roller body 3. For this reason, if the insulating film material 17 is rolled in the short side direction (hereinafter referred to as the circumferential direction) and stored in the roller body 3, the heating element sheet 7 is arranged in a cylindrical shape over the entire inner peripheral surface of the roller body 3. can do.

The pattern 5 has a substantially rectangular power supply portion 5a at both ends in the long side direction (hereinafter, referred to as an axial direction) of the insulating film material 17.
5b (see FIG. 3 for 5b). This power supply unit 5
Both a and 5b have a length slightly shorter than the short side of the insulating film material 17 in the circumferential direction, and a large number (four rows in the circumferential direction, Heating portions 5e composed of meandering patterns 5c (10 rows in the axial direction, a total of 40) are provided.

Each meandering pattern 5c has five bent portions 5d at both ends in the axial direction.
"e" is formed by sequentially connecting the meandering pattern 5c in the axial direction between the power supply units 5a and 5b. The configuration of each meandering pattern 5c will be described later in detail. In addition, the heat generating portion 5e is provided with the insulating film material 1 in the circumferential direction as a whole.
7 is formed over substantially the entire length of the pressing roller 5 in the axial direction.
3 has a slightly longer length than the press-contact portion. Furthermore,
On the surface of the heat generating portion 5e, the heat generating portion 5 is located between the heat generating portion 5e and the insulating film material 17.
e, another polyimide film 19 is stacked on the roller body 3 so as to expose the power supply units 5a and 5b.

For this reason, if the heating element sheet 7 is stored in the roller body 3 as described above, the heating section 5e extends over substantially the entire portion facing the pressing roller 53 in the axial direction and substantially entirely in the circumferential direction. It is arranged around the circumference. As shown in FIG. 3, since the heating element sheet 7 is housed in the roller body 3 with the pattern 5 inside, the insulation between the pattern 5 and the roller body 3 is ensured by the insulating film material 17. Further, since the resistance value of the heat generating portion 5e is much larger than the resistance values of the power supply portions 5a and 5b, the heat generating portion 5e generates heat when power is supplied between the power supply portions 5a and 5b. Further, the heating element sheet 7 includes a sponge tube 9.
Is pressed against the inner peripheral surface of the roller body 3, and the roller body 3 also has good thermal conductivity. And good transmission.

The polyimide film 19 is interposed between the sponge tube 9 and the heat generating portion 5e.
Even if the heating portion 5e is locally overheated for some reason, the sponge tube 9 can be prevented from being thermally damaged.
Therefore, in the heating roller 1, the power supply unit 5 has the following configuration.
An alternating current flows between a and 5b. Returning to FIG.
A pair of electrode holders 21 made of an insulating material are fitted to both ends of the roller body 3. The electrode holder 21 has a flange portion 21 that engages with the edge of the roller body 3 to prevent the roller body 3 from being embedded.
a, and is fitted inside the insulating film material 17 so as not to rotate with respect to the roller body 3 or fall off naturally. Note that the insulating film material 17 is usually merely inserted into the roller body 3 by being rolled into the roller body 3 in order to simplify the manufacturing process and prevent intrusion of air or the like. You may. The electrode holder 21 supports an electrode plate 23 made of phosphor bronze in the diameter direction of the roller main body 3, and both ends 23 a of the electrode plate 23 are bent inwardly of the roller main body 3, respectively, and are connected to the power supply section 5 a or 5 b. In contact. In addition, both ends 23a of each power supply plate 23 are 180 ° from each other of the power supply portions 5a or 5b.
Touch the displaced position.

The outer end surface of each power supply plate 23 is exposed to the outside of the electrode holder 21, and a columnar silver electrode 71 abuts in the vicinity of the center thereof. Each silver electrode 71
Are fixed to the cover 63 via support plates 73 formed by bending a band material such as phosphor bronze into a U-shape, and an AC power supply 75 (primary voltage) is connected between the pair of support plates 73. Have been. Note that a thermostat 77 is interposed between one support plate 73 and the AC power supply 75,
Abnormal heat generation is prevented.

That is, the temperature of the heating roller 1 is adjusted to a predetermined temperature by bringing a thermistor (not shown) into contact with the outer peripheral surface of the roller body 3 and controlling the amount of electricity to the support plate 73 based on the detection signal. . However, when an abnormality occurs in the control system or the like, the temperature of the heating roller 1 may increase abnormally. Therefore, in the fixing device 51, the cover 63
A thermostat 77 is provided, and when the temperature of the heating roller 1 rises abnormally, an energization path from the AC power supply 75 to the one support plate 73 is forcibly shut off. The cover 63 is made of, for example, a resin having sufficient heat resistance, such as PET (polyethylene terephthalate).

Next, the configuration of each meandering pattern 5c will be described. Returning to FIG. 4, the heating unit 5 e includes the power supply unit 5 a
(Or 5b) meandering patterns 5c1, 5c3, 5c5, 5c7, 5c9 sequentially formed from the center toward the center.
Are formed in four rows in the circumferential direction. The outer bent portion 5 of the outermost meandering pattern 5c1 in the axial direction
d0 is formed in an arc shape at a sufficient distance from the power supply section 5a (or 5b). Meandering patterns 5c1, 5
The opposing bent portions 5d1 and 5d2 of c3 are alternately arranged over the entire circumferential direction, and are formed in a substantially V-shape that enters between a pair of opposing arranged bent portions 5d2 or 5d1. Meandering pattern 5c
3, 5c5 opposing bent portions 5d3, 5d4
Are formed in an arc shape alternately arranged over the entire circumferential direction.

Further, opposing bent portions 5d5 and 5d6 of the meandering patterns 5c5 and 5c7, and the meandering pattern 5c7.
, 5c9 oppositely bent portions 5d7, 5d8,
The opposite bent portions 5d9 and 5d9 of the central meandering patterns 5c9 and 5c9 are each bent portion 5d9.
It is formed in a substantially rectangular shape having outside facing sides extending in a direction (parallel to the alternate long and short dash line C) perpendicular to the facing direction d. The interval T0 between the opposing sides of the bent portions 5d9 and 5d9 facing each other at the center is set wider than the interval T1 between the opposing sides of the bent portions 5d7 and 5d8 opposing each other.

In the fixing device 51 having the above-described structure, the bent portions 5d facing each other have a pair of bent portions (5d2 or 5d1) disposed facing each other.
V-shaped into the gap, arc-shaped alternately arranged over the entire circumferential direction, or a substantially rectangular shape having outside facing sides extending in a direction orthogonal to the direction of facing each bent portion 5d. I have. Therefore, even if the bent portions 5d facing each other are brought close to each other in the facing direction, insulation between the meandering patterns 5c can be ensured,
The pattern 5 in a portion facing the bent portion 5d
Can be increased. Therefore, pattern 5
And the amount of heat transferred from the heater can be made uniform, and the occurrence of uneven temperature can be favorably suppressed.

In addition, the bent portions 5 facing each other
d is substantially V-shaped to enter between a pair of bent portions (5d2 or 5d1) arranged oppositely, arcuately arranged alternately over the entire circumferential direction, and orthogonal to the opposing direction of each bent portion 5d. In this case, the pattern 5 is formed in a substantially rectangular shape having the opposite sides extending in the outer direction on the outer side, and the density of the pattern 5 in the opposite portion gradually decreases. Further, in the fixing device 51, the interval T0 between the opposing sides of the bent portions 5d9, 5d9 opposing each other at the center is made wider than the intervals between the other opposing sides. For this reason, the density of the pattern 5 in each bent portion 5d becomes higher toward both ends in the axial direction, and the amount of heat generated by the heat generating portion 5e also changes.

At both ends of the heating roller 1 in the axial direction, the amount of heat radiation is large and the temperature tends to be lower than that at the center.
In the fixing device 51, the amount of heat generated increases toward both ends in the axial direction. Therefore, such a difference in the amount of heat radiation can be offset to make the temperature distribution even more uniform.
Further, in the fixing device 51, the heat generating sheet 7 is pressed against the inner peripheral surface of the roller body 3 by the sponge tube 9, so that the thermal efficiency and the temperature rising speed of the heating roller 1 can be further improved.

It should be noted that the present invention is not limited to the above embodiment at all, and can be implemented in various forms without departing from the gist of the present invention. For example, in the above embodiment, the amount of heat generated is increased toward both ends in the axial direction, and the temperature distribution in the heating roller 1 is made uniform. However, when a desired temperature distribution having a specific bias is desired to be realized, Each bent portion 5d according to the temperature distribution
Can be different.

In the bent portions 5d5 to 5d9, the insulation between the meandering patterns 5c5 to 5c9 can be similarly secured regardless of whether the opposite sides are alternately arranged. Therefore, the meandering patterns 5c5 to 5c9
The number of pattern folds may be different between them. In this case, the amount of heat generated between the meandering patterns 5c5 to 5c9 can be made different depending on the change in the number of pattern folds, and a desired temperature distribution can be realized more favorably. Further, any one or two of the bent portions 5d having the substantially V-shaped, arc-shaped, or substantially rectangular shape may be used to form the heating element sheet.

Further, the heating element sheet 7 includes the roller body 3.
May be arranged along the outer peripheral surface of the second embodiment, and in this case, the same operation and effect as those of the above-described embodiment are produced. When the heating element sheet 7 is disposed along the outer peripheral surface of the roller body 3 as described above, the operation of disposing the heating element sheet 7 is further facilitated as compared with the above-described embodiment. On the other hand, in the above-described embodiment, since the heat generated by the heating element sheet 7 is conducted to the paper and the toner via the roller body 3, the temperature distribution on the surface of the heating roller 1 can be made more uniform. Can be.

In the above embodiment, the insulating film material 17 is used.
Is constituted by stacking two polyimide films, but may be constituted by one polyimide film as long as the polyimide film has sufficient insulating properties. Further, regardless of whether the heating element sheet 7 is provided on the inner peripheral surface or the outer peripheral surface of the roller body 3, the heating element sheet 7 does not necessarily require the insulating film material 17 to be provided toward the roller body 3. . For example, if some kind of insulating layer is provided on the inner peripheral surface or the outer peripheral surface of the roller main body 3, the pattern 5 can be disposed toward the roller main body 3 side.

Further, the present invention can be applied not only to the above-described printer P but also to various image forming apparatuses such as a copying machine and a facsimile. Further, the present invention is not limited to an electrophotographic image forming apparatus, and can be applied to a hot melt inkjet type image forming apparatus which forms an image by melting and ejecting solid ink at normal temperature.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of a printer to which the present invention has been applied.

FIG. 2 is a cross-sectional view illustrating a configuration of a fixing device of the printer.

FIG. 3 is a cross-sectional view of the fixing device cut along a rotation axis of a heating roller.

FIG. 4 is a plan view illustrating a configuration of a heating element sheet of the heating roller.

FIG. 5 is an explanatory diagram showing a problem of a conventional heating element sheet.

[Explanation of symbols]

1. Heating roller for fixing 3. Roller body 5
... Patterns 5a, 5b ... Power supply unit 5c ... meandering pattern
d: folded part 5e: heating part 7: heating element sheet 9
... Sponge tube 17 ... Insulating film material 23 ... Electrode plate 5
DESCRIPTION OF SYMBOLS 1 ... Fixing device 53 ... Press roller 71 ... Silver electrode 7
5: AC power supply D: Electrophotographic process unit E: Thermal fixing unit P
… Printer

Claims (5)

[Claims] 1. A fixing heating roller for heating a recording material adhered to a recording medium, and a pressing roller for pressing the recording medium on an outer peripheral surface of the fixing heating roller, wherein the recording medium is What is claimed is: 1. A fixing device for fixing a recording material adhered to a recording medium by being conveyed while being sandwiched between a fixing heating roller and a pressing roller, wherein the fixing heating roller is a cylindrical roller body; A heating element sheet formed by forming a pattern of a resistance heating element that generates heat in response to energization on an insulating film material disposed along the inner peripheral surface or the outer peripheral surface of the main body; The pattern is formed by a plurality of meandering patterns arranged with the bent portions facing each other, and the bent portions facing each other are alternately arranged over the entire circumferential direction. Wear device. 2. A fixing heating roller for heating a recording material adhered to a recording medium, and a pressing roller for pressing the recording medium on an outer peripheral surface of the fixing heating roller, wherein the recording medium is What is claimed is: 1. A fixing device for fixing a recording material adhered to a recording medium by being conveyed while being sandwiched between a fixing heating roller and a pressing roller, wherein the fixing heating roller is a cylindrical roller body; A heating element sheet formed by forming a pattern of a resistance heating element that generates heat in response to energization on an insulating film material disposed along the inner peripheral surface or the outer peripheral surface of the main body; The pattern is formed by a plurality of meandering patterns arranged with the bent portions facing each other, and the bent portions facing each other are substantially V-shaped to enter between a pair of bent portions arranged opposite to each other. Fuser, characterized in that formed. 3. A fixing heating roller for heating a recording material adhered to a recording medium, and a pressing roller for pressing the recording medium on the outer peripheral surface of the fixing heating roller, wherein the recording medium is What is claimed is: 1. A fixing device for fixing a recording material adhered to a recording medium by being conveyed while being sandwiched between a fixing heating roller and a pressing roller, wherein the fixing heating roller is a cylindrical roller body; A heating element sheet formed by forming a pattern of a resistance heating element that generates heat in response to energization on an insulating film material disposed along the inner peripheral surface or the outer peripheral surface of the main body; The pattern is formed of a plurality of meandering patterns arranged with the bent portions facing each other, and the bent portions facing each other have opposite sides extending in a direction orthogonal to the facing direction on the outside. Fuser, characterized in that it is formed in a rectangular. 4. The space between the opposite sides of the bent portions facing each other is set to be different at each portion so that a desired temperature distribution is obtained on the outer peripheral surface of the fixing heating roller. The fixing device according to claim 3, wherein: 5. A part of the bent portion of the meandering pattern facing each other has a substantially arc shape or a substantially V shape so that a desired temperature distribution can be obtained on the outer peripheral surface of the fixing heat roller.
The fixing device according to claim 3, wherein the fixing device is formed in a letter shape and arranged alternately.