JP3347712B2 - Fixing device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating apparatus for applying thermal energy to a recording material via a heat-resistant film.

[0002] This apparatus includes an electrophotographic copying machine, a printer,
An image heating and fixing device in an image forming apparatus such as a facsimile, that is, a recording material (an electro-fax sheet or an electro-fax sheet) using a toner made of a heat-meltable resin by an appropriate image forming process means such as electrophotography, electrostatic recording, and magnetic recording.
A recording material carrying an unfixed toner image corresponding to the target image information, formed directly or indirectly (transferred) on the surface of an electrostatic recording sheet, transfer material sheet, printing paper, etc. It can be used as an image fixing device for performing a heat fixing process as a permanent fixed image on a surface.

In addition, the present invention is not limited to the image forming apparatus, and can be widely used as a means or a device for heating the image bearing member, such as a device for heating a recording material carrying an image to improve the surface properties.

[0004]

2. Description of the Related Art In an image forming apparatus such as a copying machine, a heat roll fixing method is widely used as a fixing method of a toner image on a recording material.

However, this hot roll fixing method has a problem that it takes a long time to warm up the hot roll to reach a predetermined fixing temperature.

Therefore, the applicant has proposed a thermal head which instantaneously raises the temperature and a film fixing system which uses a thin film which slides on the thermal head to shorten the warm-up time, as disclosed in JP-A-63-313182 and JP-A-Hei. -157
No. 878 and the like. In a film fixing method using a thin film, an endless film is mainly used.

However, in this method, the film may meander. Therefore, a method for preventing the film from meandering is proposed in Japanese Patent Application No. 2-113185, in which one end of the endless film is thickened, a thick portion or a rib is formed, and a member for suppressing the meandering of the film is arranged in this portion. Have been.

[0008]

However, in the above-mentioned conventional example, the thick portion of the film is weak in heat and bending durability, and thus is generally separated from the heater heating portion. Therefore, the non-heat generating portion at the end of the heater has to be greatly extended to both sides. As a result, 1) the device becomes large, especially in the longitudinal direction, and 2) the heater (heating device) becomes long, and heat escapes from the ends, so that the device is completely cooled. In such a case, it takes a long time to warm up, or trying to reach a specified temperature in the same time requires a large amount of power.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a fixing device which solves the above-mentioned problems and performs good heating without increasing the size of the device.

[0010]

SUMMARY OF THE INVENTION The present invention comprises a fixed heater, a film that slides with respect to the heater, and a pressure member that forms a nip with the film. A fixing device for fixing an image to be fixed by nipping and conveying a support that supports the image to be fixed,
The film is an endless film, and the thickness of one end of the film at one end is thicker than the other portion, and the non-heat-generating portion of the heater that slides along with the rotation of the film is a thick film of the endless film. In the fixing device configured to allow the portion to pass, the length of the non-heat generating portion at the end of the heater is different at one end and the other end, and the length of the side end where the thick film portion of the film passes is different. The fixing device is characterized in that the length of the non-heating portion is longer than the length of the non-heating portion at the other end.

According to the above invention, the end of the thick film portion of the film having low durability due to heat is disposed at the non-heating portion of the heater.
In addition, by increasing the length of the non-heat generating portion of the heater only on the thick film portion side of the film, 1) preventing the temperature of the film thick film portion from rising, 2).
3) Since the size of the device is increased, especially the length in the longitudinal direction is shortened, and 3) the heat capacity of the heater is also reduced, the time required to reach the specified temperature is reduced, or the power consumption is reduced when the specified temperature is reached in the same time. Is done.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. First, a reference example of a fixing device as a premise of the present invention will be described with reference to FIGS.

FIG. 1 is a sectional view of an image forming apparatus using a fixing device according to a reference example on which the present invention is based. Reference numeral 1 denotes a document table made of a transparent member such as glass, which scans the document by reciprocating in the direction of arrow a. A short-focus small-diameter imaging element array 2 is disposed immediately below the original table 1, and the original image placed on the original table 1 is illuminated by an illumination lamp 3, and the reflected light image is reflected by the array 2. Photosensitive drum 4
It is slit-exposed on top. The photosensitive drum 4 rotates in the direction of arrow b. Reference numeral 5 denotes a charger, for example, which uniformly charges the photosensitive drum 4 coated with a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. The photosensitive drum 4 uniformly charged by the charger 5 forms an electrostatic image subjected to image exposure by the array 2. This electrostatic image (electrostatic latent image) is visualized by the developing device 6 using a powder toner made of a resin or the like that softens and melts when heated.

On the other hand, the recording material P such as recording paper stored in the cassette S is rotated while being pressed vertically in synchronization with the feed roller 7 and the image on the photosensitive drum 4 in a synchronized manner. It is fed onto the photosensitive drum 4 by a pair of conveying rollers 8. Then, by the transfer discharger 9,
The toner image formed on the photosensitive drum 4 is a recording material P
Transcribed above. Thereafter, the recording material P separated from the photosensitive drum 4 by a known separating unit is guided to a fixing device 11 by a conveyance guide 10, and is discharged onto a tray 22 after being subjected to a heat fixing process. After the transfer of the toner image, the residual toner on the photosensitive drum 4 is removed by the cleaner 23.

FIG. 2 is an enlarged sectional view of the fixing device 11.
In the figure, reference numeral 12 denotes a low-heat-capacity linear heating element fixed to the apparatus, for example, having a thickness of 1.0 mm and a width of 10 mm.
The resistive material 14 is applied to an alumina substrate 13 having a width of 1.0 mm on an alumina substrate 13 having a length of 240 mm and a length of 240 mm. Energization is DC 100V cycle 20msec
A pulse corresponding to a desired temperature and energy release amount controlled by the temperature detecting element 15
The pulse width is changed and given. The pulse width is almost 0.
5 to 5 msec.

The alumina substrate 13, the resistance material 14, and the protective layer 51 are integrally mounted on the heat insulator 53 with a heat-resistant double-sided tape or a heat-resistant adhesive. The heat insulator 53 is attached to a stay 52 that supports the heating unit. The stay 52 needs to be made of a material and a structure that does not cause a large deflection at the center even when pressed by the pressure roller 19. The temperature detecting element 15 is also attached to the alumina substrate 13 on the surface opposite to the resistance layer.

As described above, the fixing film 16 moves in the direction of the arrow in the drawing while coming into contact with the heating element 12 whose temperature and energy are controlled. An example of the fixing film 16 is a heat-resistant film having a thickness of 20 μm, for example, a release layer obtained by adding a conductive material to a fluororesin such as PTFE and PFA on at least the image contact surface side of polyimide, polyetherimide, PES, and PFA. Is an endless film coated with 10 μm. Generally, the surface in contact with the transfer material has a total thickness of less than 100 μm, and more preferably less than 70 μm.
The driving of the fixing film 16 is performed by the driving roller 17 and the driven roller 18 and the tension, and moves without wrinkles in the direction of the arrow.

Reference numeral 19 denotes a pressure roller having a rubber elastic layer of silicon rubber or the like having good releasability. The pressure roller 19 presses the heating element 12 via the fixing film 16 with a total pressure of 4 to 15 kg, and rotates by pressing against the film 16. .

The unfixed toner 20 on the recording material P is guided to a fixing section by an entrance guide 21, and a fixed image is obtained by the above-described heating.

In this embodiment, the endless film 16
Used was a heat-resistant film having a thickness of 20 μm and a polyimide film having a thickness of about 500 μm only at one end and 5 mm at the end. In the production method, dipping, drying, and firing were repeated at least 10 times only at the ends. Further, a film coated with 10 μm of PTFE except for the ends was used thereon.

FIG. 3 shows a film meandering prevention mechanism. That is, the thick film portion 16-a of the endless film 16 is pressed by the regulating member 60. In this case, the radius of curvature Ra of the edge 53a of the heat insulator 53 on which the thick film portion 16-a of the film 16 slides is equal to the radius of curvature R of the edge of the heat insulator 53 on which the other portion of the film 16 slides. than,
It is set to be large. This is shown in FIG.

In this embodiment, R is 1.0 mm, Ra
Was set to 3.5 mm, during which the radius of curvature was changed smoothly. Thereby, salmon, sharpness, and the like due to bending of the film thickness portion 16-a at the end portion were prevented, and the durability was greatly improved.

FIG. 5 shows another reference example on which the present invention is based. That is, the thickness of the film end is increased as a separate member on the base film 16 with the adhesive layer 61 interposed therebetween.
This is the case where the ribs 62 are bonded. In this case, since the rigidities of the base film 16, the adhesive 61, and the ribs 62 are different,
The durability against bending has been greatly improved. Note that heat-resistant silicone rubber, fluorine rubber, urethane, or the like was used as the rib, and a silicon-based, fluorine-based, acrylic-based, or the like was used as the adhesive, and was bonded to the surface of the base film 16. The thickness of the rib 62 was 0.5 to 2 mm.

FIG. 6 shows still another embodiment of the present invention. That is, this is an example in which the guide plate 63 is used instead of the driven roller. In this case, the radius of curvature of the guide plate is changed by Ra 'where the end thick film passes, and R' in the other portions, so that Ra '>R'. Also in this case, the durability was improved.

Although illustration is omitted, another embodiment will be described. In other words, this is a case where thickened portions are provided on both sides of the film 16. In this case, the durability of the film was improved by providing the heat insulator 53 or the guide plate 63 with portions having a large radius of curvature at both ends.

An embodiment of the present invention will now be described with reference to FIGS.
This will be described with reference to the drawings shown in FIG.

The configuration of the fixing device according to the embodiment of the present invention is the same as that shown in FIGS. FIG. 7 shows a film meandering prevention mechanism. That is, the thick film portion 116-a of the endless film 116 is pressed by the regulating member 160. The film 116 is moved to one side in advance as indicated by an arrow, and the meandering is suppressed by pressing the film thick film portion 116-a with the regulating member 160.

FIG. 8 shows an alumina substrate 113, a resistance material 1
14 is a front view of the heater 112 in which the protective layer 151 is integrated. In FIG. 8, the heating portion is made of the resistance material 114 of 1.0 m.
m and a thickness of about 10 μm on the alumina substrate 113, the width of the non-heating portion was 4.0 mm, and a low-resistance material 114 ′ was coated thereon with a width of 6.0 mm to form electrodes.
Note that ruthenium oxide, silver palladium, or the like was used as the resistance material 114, and silver, platinum, gold, or the like was used as the low-resistance material 114 ′. The length b of the heat generating portion is set to be slightly larger than the maximum paper passing size or the maximum image area length. For example, when passing A3-size paper, it is set to about 230 mm when passing A4-size paper. In the non-heat-generating portion of the heater 112, the length c of the side on which the thick film portion 116-a of the film 116 passes is longer than the length d of the other end. This is because in order to lower the temperature of the portion A through which the thick film portion of the film 116 passes, it is necessary to be farther away from the heater 112 than the other end.

In this embodiment, c = 50 mm and d = 20
mm, the temperature at which the thick film portion 116-a of the film 116 passed was sufficiently lowered, so that the durability of the film 116 was improved. The relationship between the distance from the end of the heater to the end of the heater and the temperature is such that as the distance from the heater to the non-heater of the heater 112 increases, the temperature decreases. By further increasing the value of c, the thick portion 116-a of the film 116
And the temperature dropped further. Therefore, it is thought that the durability is improved. Although the alumina substrate 113 of the heater is extended only on one side, that is, on the side of c, since the heat capacity is smaller than the case where both sides are extended, the time for warming to a certain temperature is short, and the same time is constant. To reduce the temperature to lower power.

Further, since only one side of the heater 112 is extended, there is also an advantage that the size of the apparatus is hard to be increased.

FIGS. 9 to 11 show modifications of the present embodiment. FIG. 9 shows that the film thickness at the edge of the film
16 are provided as separate members on the rib
This is the case in which In this case, the base film 11
6, the rigidity of the adhesive 161 and the rib 162 are different,
Since the adhesive force of the adhesive 161 with respect to the temperature rise has been reduced, it has conventionally been difficult to achieve both the miniaturization and the reduction of the power consumption or the weight reduction in order to prevent the temperature rise,
This has been realized in the present embodiment.

FIGS. 10 to 11 show the case where the material and shape of the non-heat generating portion at the end of the heater are changed. That is, FIG. 11 shows a case where the width of the resistance material 114 is greatly increased and the low resistance material 114 ′ as an electrode is disposed only at the end portion, and practically hardly heat is generated. FIG. 11 shows a case in which the thickness of the resistance material 114 is also greatly increased only in the non-heat generating portion. In this case, heat generation hardly occurs.

[0033]

As described above, according to the first aspect of the present invention, when an endless film having one end portion thicker than the other end portion is used, the end portion of the thick film portion of the film which is less durable due to heat. Is disposed in the non-heat-generating portion of the heater, and the non-heat-generating portion of the heater is lengthened only on the thick film portion side of the film, thereby 1) preventing the temperature of the film thick film portion from rising, and 2) increasing the size of the apparatus, especially Since the length in the longitudinal direction is shortened and 3) the heat capacity of the heater is also reduced, the time required to reach the specified temperature is shortened, or the power consumption is reduced when the specified temperature is reached in the same time.

[Brief description of the drawings]

FIG. 1 is a sectional view of a copying machine showing a reference example on which the present invention is based.

FIG. 2 is a sectional view of a fixing device of the copying machine shown in FIG. 1;

FIG. 3 is a sectional view of a film and a regulating member of the fixing device of FIG. 2;

FIG. 4 is a diagram illustrating a heat insulating member of the fixing device of FIG. 2;

FIG. 5 is a diagram showing another reference example of a fixing device on which the present invention is based.

FIG. 6 is a diagram showing still another reference example of a fixing device on which the present invention is based.

FIG. 7 is a cross-sectional view of a film and a regulating member according to the embodiment of the fixing device of the present invention.

FIG. 8 is a top view of a heater of the fixing device according to the embodiment of the present invention.

FIG. 9 is a sectional view of a film showing a modification of the fixing device according to the embodiment of the present invention.

FIG. 10 is a top view showing a modification of the heater of the fixing device according to the embodiment of the present invention.

FIG. 11 is a top view showing another modification of the heater of the fixing device according to the embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 16 ... Film 16a ... Film thick film part 17 ... Driving roller 18 ... Driven roller 19 ... Pressure roller R, Ra ... Heat insulator 53
R ', R'a: radius of curvature of film guide 63 114: resistance heating element 114': low resistance material (electrode) 116: film 116a: film thick film portion 161: adhesive layer 162: rib

Continued on the front page (72) Inventor Atsushi Asai 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Katsuaki Kobayashi 3-30-2, Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. (72) Inventor Shigeo Kimura 3-30-2 Shimomaruko, Ota-ku, Tokyo Canon Inc. (72) Inventor Akira Yamamoto 3-30-2 Shimomaruko 3-chome, Ota-ku, Tokyo Canon Inc. (72) Invention Person Kensaku Soka 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (72) Inventor Atsushi Atsushi 3-30-2 Shimomaruko, Ota-ku, Tokyo Inside Canon Inc. (56) References 3-136082 (JP, A) JP-A-4-86247 (JP, A) JP-A-3-25477 (JP, A) JP-A-2-81552 (JP, U) (58) Fields investigated (Int. Cl. ^7, DB name) G03G 13/20 G03G 15/20

Claims (1)

(57) [Claims] 1. A support having a fixed heater, a film sliding with respect to the heater, and a pressing member forming a nip with the film, and supporting an image to be fixed between the film and the pressing member. A fixing device for fixing the image to be fixed by pinching and conveying the film, wherein the film is an endless film, and the thickness of one end of one side of the film is thicker than other portions, In the fixing device, the thick film portion of the endless film passes through a non-heat generating portion of the heater that slides with the rotation, and a length of the non-heat generating portion at an end of the heater is one end. And a length of the non-heat generating portion at the side end through which the thick film portion of the film passes is longer than a length of the non-heat generating portion at the other end.