JPH09197864A - Heating fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating fixing device where the wrinkles of recording material at the time of fixing is prevented. SOLUTION: The recording material carrying an unfixed image passes through a fixing nip part constituted by making a fixing member composed of a heating heater supported by a heat insulating stay holder 12 and fixing film press-contact with a pressure roller 20, so that the unfixed image carried by the recording material is fixed. Then, the pressure roller 20 is made in the shape of an inverse crown, and the surface of the heating heater of the heat insulating stay holder 12 is made in the shape of a normal crown, and the normal crown quantity CR of the heat insulating stay holder 12 is set larger than the inverse crown quantity CR' of the pressure roller 20 (CR>CR'). Thus, an effect for pulling the recording material on both sides is obtained while fixing and carrying the recording material at the inside of the fixing nip part, so that the generation of the wrinkles of the recording material is prevented, and the nip quantity at a center and both ends is maintained to be nearly equal, so that high fixing performance is obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat fixing device provided in an image forming apparatus for forming an image through an image forming process such as an electrophotographic system and an electrostatic recording system.

[0002]

2. Description of the Related Art Conventionally, as a heat fixing device, a device using a heat roller system or a film heating system has been widely used. In particular, a method that keeps power consumption as low as possible without supplying power to the heating and fixing device during standby,
A heat fixing method by a film heating method has been proposed in which a toner image on a recording material is fixed through a film between a heater unit and a pressure roller (Japanese Patent Laid-Open No. 63-313182).
JP-A-2-157878, JP-A-4-44075,
See Japanese Patent Application Laid-Open No. 4-204980, etc.).

FIG. 12 shows a schematic structure of a main part of a heating and fixing device adopting a film heating system. The device is a heating heater 141 fixedly supported by a heat insulating stay holder (support) 142, and the heater 141. A heat-resistant thin film (hereinafter referred to as a fixing film) 143 is sandwiched between the elastic pressure roller 150 and a nip portion (fixing nip portion) N having a predetermined nip width. . The heater 141 is heated / controlled to a predetermined temperature by being energized. The fixing film 143 is composed of a cylindrical member, an endless belt member, or a roll-wound end-web member. The fixing member 143 is applied to the heater 141 surface at the fixing nip portion N by the driving force (not shown) or the rotational force of the pressure roller 150. It is conveyed and moved in the direction of arrow a in the figure while closely contacting and sliding.

The heater 141 is heated to a predetermined temperature and temperature-controlled,
When the recording material P as a heated material is supplied between the fixing film 143 in the fixing nip portion N and the pressure roller 150 in a state where the fixing film 143 is conveyed and moved in the direction of the arrow a, the recording material P is fixed. The fixing film 143 is conveyed in close contact with the surface of the film 143 while sandwiching the fixing nip portion N together with the fixing film 143. Then, in the fixing nip portion N, the recording material P is heated by the heater 141 via the fixing film 143, and the unfixed toner image t carried on the recording material P is held.
Is heat-fixed. The recording material P that has passed through the fixing nip portion N is separated from the surface of the fixing film 143 and conveyed.

By the way, the heater 141 as a heating member
For this, a ceramic heater is generally used. The heater 141 is provided, for example, on the surface (the surface facing the fixing film 143) of the ceramic substrate 141a having electrical insulation, good thermal conductivity, and low heat capacity such as alumina along the substrate length (direction perpendicular to the drawing). Silver Palladium (Ag / Pb) / Ta
An energization heating resistance layer 141b of ₂ N or the like is formed by screen printing or the like, and the surface on which the energization heating resistance layer 141b is formed is covered with a thin glass protective layer 141c.

In the ceramic heater 141, when the energization heating resistance layer 141b is energized, the energization heating resistance layer 141b generates heat and the heater 141 including the ceramic substrate 141a and the glass protective layer 141c.
The entire temperature rises rapidly. The temperature of the heater 141 is detected by a temperature detecting means (not shown) provided on the back surface of the heater 141 and fed back to an energization controller (not shown). Then, the energization control unit controls the power supply to the energization heat generating resistance layer 141b so that the temperature of the heater 141 detected by the temperature detecting means is maintained at a predetermined substantially constant temperature (fixing temperature), and the heater 141 is set to the predetermined fixing. Heated / controlled to temperature.

The fixing film 143 has a thickness of 20 to 70 μm, which is set to be fairly thin, in order to efficiently apply the heat of the heater 141 to the recording material P as a material to be heated in the fixing nip portion N. The fixing film 143 is composed of three layers of a film base layer, a primer layer, and a release layer. The film base layer side is located on the heater 141 side and the release layer is located on the pressure roller 150 side. The film base layer is made of polyimide, polyamideimide, PEEK or the like having higher insulation than the glass protective layer 141a of the heater 141, and has high heat resistance and elasticity. Further, the film base layer maintains mechanical strength such as tear strength of the entire fixing film 143. The primer layer is a thin layer having a thickness of about 2 to 6 μm, and the releasable layer is the fixing film 14.
3 is a toner offset prevention layer for 3, which is a PF
A fluororesin such as A, PTFE or FEP is coated to a thickness of about 10 μm.

The heat insulating stay holder 142 is made of, for example, a heat-resistant plastic member, holds the heater 141 for heating, and fixes the fixing film 1.
It also serves as a conveyance guide for 43.

In the film heating type heat fixing apparatus using such a thin fixing film 143, since the ceramic heater 141 has high rigidity, the pressure roller 150 having the elastic layer 151 is pressed against the heater 141.
The fixing nip portion N having a predetermined width is formed by deforming the pressing contact portion into a flat shape along the flat lower surface, and by heating only the fixing nip portion N, quick-start heat fixing is realized.

[0010]

However, in the conventional heat-fixing device employing the film heating system,
When the paper, which is a recording material, passes through the fixing device, wrinkles may occur on the paper in the fixing nip portion. This wrinkle is likely to occur especially on thin paper.

Conventionally, in a heat roller type heat fixing device which is generally used, a fixing nip is formed by giving an outer crown shape to the outer diameter of the fixing roller (outer diameter is about 50 to 300 μm and a thick end). A method is used in which the paper conveyance speed in each section is increased at both ends and slowed in the center to generate a force to pull the paper to both sides, thereby preventing the occurrence of paper wrinkles.

On the other hand, in the heat fixing device employing the film heating method, the fixing film corresponds to the heat roller, but it is extremely difficult to give this fixing film an inverted crown shape. There is no unexpected method to form an inverted crown shape due to the difference in thickness of the fixing film, and even if it has an inverted crown shape at the center and the end portion due to its inner diameter and outer diameter, when it is pressed at the fixing nip portion. It is easily flattened.

However, if the fixing film is provided with a difference in thickness between the center and the end, the thickness of the end must be increased, and the fixability of the end is extremely deteriorated.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a heat fixing device capable of preventing wrinkles from being generated on a recording material during fixing.

[0015]

In order to achieve the above object, the invention according to claim 1 is such that a recording material carrying an unfixed image is composed of a heater for heating supported by a heat insulating stay holder and a thin film. By passing through the fixing nip part formed by pressing the fixing member and the pressure roller to each other,
In a heat fixing device for fixing an unfixed image carried on the recording material, the pressure roller has an inverted crown shape, the heating heater surface or the heating heater of the heat insulating stay holder has a regular crown shape, and The feature is that the positive crown amount of the stay holder is set to be larger than the reverse crown amount of the pressure roller.

According to a second aspect of the present invention, a recording material carrying an unfixed image is brought into pressure contact with a heating heater supported by a heat insulating stay holder, a fixing member composed of a thin film, and a pressure roller. In the heating and fixing device, an unfixed image carried on the recording material is fixed by passing through the fixing nip portion, and a discharge roller for conveying the recording material is provided immediately after the fixing nip portion. It is characterized in that the conveying speed of the discharge roller is set to be faster at both ends with respect to the center in the longitudinal direction, or the conveying direction of the discharge roller is directed to the outside at both ends.

Therefore, according to the first aspect of the present invention, the effect of pulling the recording material to both sides while fixing and transporting the recording material in the fixing nip portion can be obtained, so that wrinkles are not generated in the recording material. In addition to the prevention, the nip amount at the center and the nip amount at both ends can be kept substantially the same, so that a high fixing property can be obtained.

Further, according to the second aspect of the invention, since the effect of pulling the recording material to both sides immediately after the fixing nip portion can be obtained, it is possible to prevent the recording material from wrinkling.

[0019]

Embodiments of the present invention will be described below with reference to the accompanying drawings.

<Embodiment 1> FIG. 1 is a block diagram of an essential part of an image forming apparatus provided with a heat fixing device according to the present invention. The process speed of the image forming apparatus according to the present embodiment is 9
4 mm / sec.

In FIG. 1, reference numeral 1 is a photosensitive drum, and the photosensitive drum 1 is constructed by coating a photosensitive material such as OPC on a cylindrical substrate made of aluminum, nickel or the like. This photosensitive drum 1 is rotationally driven in the direction of the arrow in the figure, and first, the surface thereof is a charging roller 2 as a charging device.
Are uniformly charged by. Next, turn on according to the image information
Scanning exposure is performed by the laser beam 3 controlled to be turned on / off, and an electrostatic latent image is formed on the photosensitive drum 1. This electrostatic latent image is developed by the developing device 4 and visualized as a toner image. As the developing method, a jumping developing method, a two-component developing method, a FEED developing method, etc. are used.
Image exposure and reversal development are often used in combination.

Thus, the visualized toner image is transferred from the photosensitive drum 1 onto the recording material P conveyed at a predetermined timing by the transfer roller 5 as a transfer device.
At this time, the recording material P is nipped and conveyed between the photosensitive drum 1 and the transfer roller 5 with a constant pressure, and the recording material P carrying the unfixed toner image is conveyed to the heat fixing device 6 according to the present invention.
The heat fixing device 6 receives the fixing of the toner image.
The transfer residual toner remaining on the photosensitive drum 1 without being transferred to the recording material P is removed from the surface of the photosensitive drum 1 by the cleaning device 7.

Next, the structure of the heat fixing device 6 according to the present invention will be described with reference to FIG.

FIG. 2 is a cross-sectional view showing the structure of the heating and fixing device 6. In FIG. 2, 10 is a fixing member, and the fixing member 10 is composed of a fixing film 13 and a heater 11 for heating.

The fixing film 13 is a thin film having a small heat capacity. Specifically, the fixing film 13 is 100 in order to enable quick start.
Polyimide, polyamideimide, PEEK, PES, PPS, P having heat resistance and thermoplasticity with a thickness of μm or less
It is made of a film such as FA, PTFE or FEP. Further, the thickness of the fixing film 13 needs to be 20 μm or more in order to have a sufficient strength for constructing a long-life heat fixing device and to secure high durability. Therefore, the thickness of the fixing film 13 is 20 μm or more, 1
The optimum value is 00 μm or less. In order to prevent the offset of the toner and to ensure the separability of the recording material P, the surface of the fixing film 13 is mixed with a heat-resistant resin having a high releasability such as PFA, PTFE, FEP, and a silicone resin, or is used alone. Need to be covered with. In this embodiment, the fixing film 1
3 is formed by forming a primer layer of about 4 μm and a releasable layer of about 10 μm on a polyimide film having a diameter of 25 mm and a thickness of 50 μm.

The heating heater 11 is provided inside the fixing film 13, and the heating heater 11 heats the toner image on the recording material P at the fixing nip portion to heat the toner image on the recording material P. Fix it. The heater 11 for heating is provided with a heat-generating resistance layer of Ag / Pd (silver palladium), RuO ₂ , Ta ₂ N, etc. on the surface of a highly insulating ceramic substrate such as alumina by screen printing along the longitudinal direction. It has a thickness of about 10 μm and a width of about 1 to 5 mm and is applied in a linear or strip shape.

Reference numeral 12 denotes a heat insulating stay holder which holds the heater 11 for heating and prevents heat radiation in the direction opposite to the fixing nip portion, and is made of liquid crystal polymer, phenol resin, PPS, PEEK or the like. There is. The fixing film 13 is loosely fitted on the heat insulating stay holder 12 with a margin, and the fixing film 13 is rotationally driven in the direction of the arrow in the figure. Since the fixing film 13 rotates while rubbing against the internal heating heater 11 and the heat insulating stay holder 12, it is necessary to suppress the frictional resistance between the heating heater 11 and the heat insulating stay holder 12 and the fixing film 13 to be small. . Therefore, the heating heater 1
A small amount of a lubricant such as heat resistant grease is applied to the surfaces of the heat insulating stay holder 1 and the heat insulating stay holder 12, so that the fixing film 13 can rotate smoothly.

The pressure roller 20 as a pressure member is
Elastic layer 2 formed by foaming heat resistant rubber such as silicone rubber or fluororubber or silicone rubber on the outside of the core metal 21
2 to form the elastic layer 2 as in the present embodiment.
A releasable layer 23 made of PFA, PTFE, FEP or the like may be formed on the second layer 2.

In order to form a fixing nip portion necessary for heat fixing between the pressure roller 20 and the fixing film 13, the pressure roller 20 is sufficiently pressed from both end portions in the longitudinal direction by a pressing means (not shown). By receiving a driving force from one end portion in the longitudinal direction via the cored bar 21, it is rotationally driven in the direction of the arrow in the figure. As a result, the fixing film 13 is driven to rotate outside the heat insulating stay holder 12 in the direction of the arrow in the figure.
A drive roller (not shown) may be provided inside the fixing film 13 and the fixing film 13 may be rotated by rotationally driving the drive roller.

In FIG. 3, the heat insulating stay holder 12 is attached to the recording material P.
The state seen from the advancing direction of is shown.

In this embodiment, the heat insulating stay holder 1 is used.
2 is made of PPS, and as shown in FIG. 3, the heat insulating stay holder 12 does not have a flat surface on the fixing nip surface side (that is, the heater 11 surface side) but a downward convex convex crown shape. doing. In FIG. 3, the heat insulating stay holder 1
The positive crown amount of 2 is indicated by CR, and the heat insulating stay holder 12 is swollen by the height of CR at the maximum portion with respect to the straight line shown by the dotted line.
The size of R is set to 450 μm. This will be described later. Since the heating heater 11 is attached to the heat insulating stay holder 12, the heating heater 1
1 also has a regular crown shape following the surface shape of the heat insulating stay holder 12.

Here, a method of measuring the positive crown amount CR of the heat insulating stay holder 12 will be described.

The heat insulating stay holder 12 is turned upside down and placed on a horizontal surface plate, and the surface of the heater 11 is measured with a height gauge or a micrometer. For the pressure roller 15, the amount of reverse crown is measured by a laser outer diameter length measuring machine.

By the way, the positive crown amount CR is defined as the difference in height between the longitudinal center and the longitudinal end on the surfaces of the heat insulating stay holder 12 and the heater 11, as shown in FIG. FIG. 4 shows a state in which the pressure roller 20 is viewed from the traveling direction of the recording material P.
R'is defined as the difference (D2-D1) / 2 between the outer diameter D1 at the longitudinal center of the pressure roller 20 and the outer diameter D2 at the end. In this embodiment, the reverse crown amount CR ′ of the pressure roller 20 is set to 150 μm.

As described above, in the present embodiment, the fixing nip surface of the heat insulating stay holder 12 has a regular crown shape, and the pressure roller 20 has an inverted crown shape. Table 1 shows the relationship between the size of the positive crown amount CR of the heat insulating stay holder 12 and the reverse crown amount CR ′ of the pressure roller 20 and the frequency of occurrence of wrinkles (paper wrinkles) on the recording material P.

[0036]

[Table 1] According to Table 1, the wrinkle occurrence frequency was 77/100 when the positive crown amount CR of the heat insulating stay holder 12 was 0 μm and the reverse crown amount CR ′ of the pressure roller 20 was 0 μm. From here, set the positive crown amount CR of the heat insulating stay holder 12 to 15
When it is increased to 0,300 μm, the speed at the fixing nip portion becomes faster at the end portion and slower at the center portion, so that the degree of wrinkles gradually becomes better. This principle is shown in FIG.

In FIG. 5, the pressure roller 20 is crushed into an inverted crown shape by the regular crown shape of the heat insulating stay holder 12, and the radius of gyration in the fixing nip portion is large at both ends and small at the central portion. It is shown that the conveyance speed is high, the conveyance speed at the center is low, a force pulling the recording material P to both sides is generated, and the wrinkle level of the recording material P is improved.

As shown in Table 1, the heat insulating stay holder 1
When the positive crown amount CR of 2 was increased to 450 μm, wrinkles did not occur on the recording material P. However, looking at the fixing nip amount at this time, it was 9 mm at the center and 6 mm at the end, and the fixing property was poor at the end.

Therefore, the reverse crown amount C of the pressure roller 20 is
R ′ is combined with the positive crown amount CR of the heat insulating stay holder 12. In the present embodiment, the experiment was conducted with the reverse crown amount CR ′ of the pressure roller 20 set to 150 μm. Positive crown amount CR = 0 μm, reverse crown amount C
When R ′ = 150 μm, there is little effect on wrinkles.
This is the reverse crown amount C on the elastic layer 22 of the pressure roller 20.
This is because the elastic layer 22 is crushed in the fixing nip portion even if R ′ = 150 μm is applied, and the effect of the reverse crown is not seen.

By combining the inverted crown shape of the pressure roller 20 and the regular crown shape of the heat insulating stay holder 12, both the wrinkle prevention effect and the high fixing property are achieved. The crown amount CR of the heat insulating stay holder 12 and the reverse crown amount CR ′ of the pressure roller 20 collectively shown in Table 2 are necessary for preventing wrinkles, but the heat insulating stay holder 12
Has a structure in which pressure is applied at both ends in order to apply pressure with the fixing film 13 covered. Since the pressure roller 20 is heated and pressed by the heat insulating stay holder 12 made of resin, the pressure roller 20 is bent in a direction to cancel the positive crown amount CR of the heat insulating stay holder 12. Therefore, unless the positive crown amount CR of the heat insulating stay holder 12 is made larger than the reverse crown amount CR ′ of the pressure roller 20, the pressing force in the vicinity of the longitudinal center becomes weak and the central fixing property deteriorates.

If only the positive crown amount CR of the heat insulating stay holder 12 is increased and the reverse crown amount CR ′ of the pressure roller 20 is set to 0, the central pressing force increases, but
The pressure applied to the end portions becomes weak and the fixing property at the end portions deteriorates.

The better results can be obtained by providing the heat insulating stay holder 12 with a normal crown and the pressure roller 20 with a reverse crown, and the positive crown amount CR> the reverse crown amount C.
It turns out that this is the case when the R'relationship holds. still,
In this experiment, recycled paper of 64 g / m ² was used as the recording material P.

[0043]

[Table 2] Upper stage: wrinkles Middle stage: fixability (end portion) Lower stage: fixability (center) <Second Embodiment> Next, a second embodiment of the present invention will be described.

Since the entire structure of the heat fixing device according to the present embodiment is the same as that of the first embodiment, the description thereof will be omitted.

In the present embodiment, as shown in FIG. 6, the regular crown shape attached to the heater surface side of the heat insulating stay holder 32 is not a curved (parabolic) regular crown shape but a trapezoidal straight line. It has a convex shape that is tied down. The reverse crown shape of the pressure roller 40 is not a curved line but a trapezoidal linear shape. This is shown in FIG. Reference numeral 32 denotes a heat insulating stay holder used in the present embodiment. As described above, the heat insulating stay holder 32 has a heater surface side having a trapezoidal downward convex shape. In FIG. 6, CR indicates the positive crown amount of the heat insulating stay holder 32, and CR ′ indicates the reverse crown amount of the pressure roller 40.

The materials of the heat insulating stay holder 32 and the pressure roller 40 are the same as those in the first embodiment. Then, also in the present embodiment, the same effect as that of the first embodiment is obtained.

<Third Embodiment> Next, a third embodiment of the present invention will be described.

Since the entire structure of the heat fixing device according to the present embodiment is the same as that of the first embodiment, the description thereof will be omitted.

In the present embodiment, as shown in FIG. 7, the heat insulating stay holder 33 is not provided with a crown shape, but is formed into a straight shape and has a regular crown to the plate thickness of the ceramic heater 34 attached to the surface of the heat insulating stay holder 33. It has a shape. The plate thickness of the ceramic heater 34 is 1.05 m at the center in order to obtain the same effect as that of the first embodiment.
m and 0.60 mm at the end.

Further, the pressure roller 40 does not have an inverted crown shape on the outer diameter but has a straight shape, and the core metal 41 inside has a regular crown shape. This pressure roller 40
Has a straight shape with an outer diameter of 23 mm at room temperature, and the thickness of the cored bar 41 is set to 17 mm at the center and 15 mm at the ends. Therefore, the thickness of the elastic layer 42 is 3 mm at the center and 4 mm at the ends. Due to thermal expansion of the elastic layer 42 during heating temperature control, the outer diameter of the pressure roller 40 is about 100 μm at the center and at the ends. The pressure was increased by about 300 μm, and the pressure roller 40 secured a reverse crown amount CR ′ of about 100 μm.

Thus, also in the present embodiment, the wrinkle preventing effect is obtained as in the case of the first embodiment.

As described above, by providing a regular crown shape on the heat insulating stay holder 33 side and an inverted crown shape on the pressure roller side 40 in the fixing nip portion, paper wrinkles are generated in the heat fixing device using the fixing film. I was able to prevent it.

<Fourth Embodiment> Next, a fourth embodiment of the present invention will be described.

FIG. 8 is a plan view of the heat fixing device according to this embodiment. In FIG. 8, the fixing film 13
However, in the heat fixing device according to the present embodiment, the heat insulating stay holder 12 shown in FIG.
The ceramic heater 11 and the pressure roller 20 are included.

The fixing film 13 rotates in the direction of the arrow in the figure, and conveys the recording material P while heating and fixing the recording material P. Downstream side of the fixing film 13 (downstream side in the conveyance direction of the recording material P)
Includes three discharge rollers 45, which are connected to the drive shaft 48.
46 and 47 are arranged, and these paper discharge rollers 45 to
By rotating in the direction of the arrow shown in the drawing, the paper 46 nips and conveys the recording material P immediately after fixing with a roller (not shown).
The paper discharge rollers 45 to 47 are made of silicon rubber (roller hardness 60 ° JIS-A).

The discharge roller 46 located at the center in the width direction has an outer diameter of 10 mm and rotates at the same speed as the process speed.

On the other hand, the discharge rollers 45 and 4 located at the ends
7 has an outer diameter of 11 mm, and both paper discharge rollers 4
Since 5 and 47 are attached to the same drive shaft 48 as the central paper ejection roller 46, their angular velocities are the same as those of the central paper ejection roller 46, but the conveyance speed is central because the outer diameter is large. 10% of that of the paper ejection roller 46
It's getting faster. The pressing force acting between the discharge rollers 45 to 47 and the rollers is 500 g each, and the discharge rollers 45 to 47 are
The width of each roller is set to 15 mm. Further, the total pressure of the heat insulating stay holder 12 and the pressure roller 12 is 10
set to kg, fixing nip width 5 mm, pressure roller 1
Since the longitudinal dimension of 2 is set to 220 mm, the pressure per unit area is about 9 g / mm ² .

The effect of this embodiment is shown in Table 3 in comparison with the conventional example (one in which the outer diameters of the discharge rollers are set to be the same).

[0059]

[Table 3] Table 3 shows total pressures of 5 to 20 in the present embodiment and the conventional example, respectively.
The results of examination of wrinkle occurrence frequency and fixability by changing to kg are shown. According to the present embodiment, the effect that the paper discharge roller pulls the paper to both sides appears, the occurrence of wrinkles is small, and the total pressure is 2
Wrinkles occur only when the weight is set to 0 kg.

On the other hand, in the comparative conventional example in which the paper discharge roller has no effect of pulling the paper to both sides, wrinkles do not occur only when the total pressure is 5 kg, and in other cases, wrinkles occur. As for the appearance of wrinkles, it was common that one or three lines were placed in the center of the paper.

Incidentally, in this embodiment, as in the above-mentioned embodiment, the reproduction of 64 g / mm ² was used as the recording material.
Further, in the present embodiment, the position of the discharge roller is provided at a position of about 20 mm downstream of the fixing nip portion.
Although the position of the paper discharge roller closer to the fixing nip portion is effective as a measure against wrinkles, good results can be obtained by disposing the paper discharge roller within about 50 mm downstream of the fixing nip portion.

<Fifth Embodiment> Next, a fifth embodiment of the present invention will be described.

FIG. 9 is a plan view of the heat fixing device according to this embodiment. In FIG. 9, the fixing film 13
And only the discharge rollers 51, 52, 53 are shown,
In the heat fixing device according to the present embodiment, the heat insulating stay holder 12, the ceramic heater 11 shown in FIG.
The pressure roller 20 and the like are included.

In the present embodiment, the discharge rollers 5 at both ends are
Each of 1 and 53 is provided at an angle of about 10 ° so as to have a conveying force toward the outside.

The materials and hardness of the paper discharge rollers 51 to 53 are the same as those in the fourth embodiment. Further, the discharge rollers 51 to 53
Has an outer diameter set to 10 mm and rotates at the same speed as the process speed, and the pressing force acting between the roller and a roller (not shown) is set to 500 g each.

In the present embodiment, the paper discharge rollers 51, 53
However, since the recording material P immediately after the fixing nip portion is pulled to both sides, an effective effect against wrinkles was obtained. The results are shown in Table 4.

[0067]

[Table 4] As shown in Table 4, the wrinkle levels were compared by changing the total pressure applied to 5 to 20 kg. In this embodiment, the discharge rollers 51 and 53 pull the recording material P to both sides, so that the frequency of wrinkles is low, and wrinkles are generated only when the total pressure is 20 kg. On the other hand, in the conventional example, the frequency of wrinkles was high, and wrinkles occurred at a total pressure of 10 kg or more.

As described above, also in this embodiment,
It was found that it is effective against the occurrence of wrinkles as in the above-mentioned embodiment.

The angles of the discharge rollers 51 and 53 are 5 to 3
The range of 0 ° was effective for wrinkles. When the angle is 5 ° or less, there is no effect on wrinkles, and when the angle is 30 ° or more, the recording material P is scratched or diagonal wrinkles are formed on both ends of the recording material P. What was good was around 10 ° used in the present embodiment.

<Sixth Embodiment> Next, a sixth embodiment of the present invention will be described.

FIG. 10 is a plan view of the heat fixing device according to the present embodiment, and FIG. 11 is a front view of the paper discharge roller and the paper discharge roller. Although only the fixing film 13 and the discharge rollers 54, 55, 56 are shown in FIG. 10, the heat fixing device according to the present embodiment includes the heat insulating stay holder 12 and the ceramics shown in FIG. The heater 11 and the pressure roller 20 are included.

In the present embodiment, as shown in FIG. 11, the discharge rollers 57, 59 located at both ends of the discharge rollers 57, 58, 59 have a predetermined angle with respect to the conveying direction of the recording material P. It is characterized by being inclined. With this configuration, the effect of pulling the recording material P to both sides can be obtained, and the wrinkling of the recording material P can be prevented. In this embodiment, the inclination angle of the paper discharge rollers 57 and 59 is set to about 15 °.

As the material of the paper discharge rollers 54, 55, 56, silicon rubber is selected similarly to the above-mentioned embodiment, and its outer diameter is set to 10 mm and its width is set to 15 mm.
It is driven to rotate at the same speed as the process speed.

The paper discharge rollers 57, 58 and 59 are made of POM, the width thereof is 10 mm, the outer diameter is 15 mm, and the pressure acting between the paper discharge rollers 54 to 57 is set to 1000 g. In addition, in the present embodiment, in order to obtain the same effect as in the case of obliquely feeding each of the discharge rollers as in the fifth embodiment, the discharge rollers 57 to 59 and the discharge rollers 54 to 5 are obtained.
The pressure between 7 and 1000 g is large as compared with the fifth embodiment.
Set to.

Further, in this embodiment, the paper discharge rollers 54 to
The configuration can be simplified as compared with the fifth embodiment in that the number of drive shafts 60 of 57 can be one.

Thus, also in the present embodiment, the same effect as the effect shown in Table 4 obtained in the fifth embodiment is obtained against wrinkles.

In the above embodiment, silicon rubber is used for the paper discharge roller, but the present invention is not limited to this, and the same effect can be obtained by using CR rubber. Further, as a measure against wrinkles, it is possible to use the above embodiments in combination.

[0078]

As is apparent from the above description, claim 1
According to the described invention, the recording material is fixed in the fixing nip portion.
Since the effect of pulling the recording material to both sides while being conveyed can be obtained, wrinkles can be prevented from occurring on the recording material, and the nip amounts at the center and both ends can be kept substantially the same, which is high. Fixability can be obtained.

According to the second aspect of the present invention, since the effect of pulling the recording material to both sides immediately after the fixing nip portion can be obtained, it is possible to prevent the recording material from wrinkling.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a main part of an image forming apparatus including a heat fixing device according to the present invention.

FIG. 2 is a cross-sectional view of a heat fixing device according to the present invention.

FIG. 3 is a front view of a heat insulating stay holder of the heat fixing device according to the first embodiment of the present invention.

FIG. 4 is a front view of a pressure roller of the heat fixing device according to the first embodiment of the present invention.

FIG. 5 is a diagram for explaining a conveyance speed in a fixing nip portion of the heat fixing device according to the first embodiment of the present invention.

FIG. 6 is a front view of a heat insulating stay holder and a pressure roller of the heat fixing device according to the second embodiment of the present invention.

FIG. 7 is a front view of a heat insulating stay holder and a pressure roller of the heat fixing device according to the third embodiment of the present invention.

FIG. 8 is a plan view of a heat fixing device according to a fourth embodiment of the present invention.

FIG. 9 is a plan view of a heat fixing device according to a fifth embodiment of the present invention.

FIG. 10 is a plan view of a heat fixing device according to a sixth embodiment of the present invention.

FIG. 11 is a front view of a paper discharge roller and a paper discharge roller of a heat fixing device according to a sixth embodiment of the present invention.

FIG. 12 is a sectional view of a main part of a conventional heat fixing device.

[Explanation of symbols]

 10 Fixing Member 11 Heating Heater 12 Insulation Stay Holder 13 Fixing Film 20,40 Pressure Roller 32,33 Insulation Stay Holder 43-47 Paper Ejection Roller 51-56 Paper Ejection Roller 57-59 Paper Ejection CR CR Regular Crown CR ' Reverse crown amount

Claims (2)

[Claims] 1. A recording material carrying an unfixed image is passed through a fixing nip formed by pressing a heating heater supported by a heat insulating stay holder, a fixing member made of a thin film, and a pressure roller against each other. As a result, in the heat fixing device for fixing the unfixed image carried on the recording material, the pressure roller has an inverted crown shape, and the heating heater surface of the heat insulating stay holder or the heating heater has a regular crown shape. At the same time, the heat fixing device is characterized in that the positive crown amount of the heat insulating stay holder is set to be larger than the reverse crown amount of the pressure roller. 2. A recording material carrying an unfixed image is passed through a fixing nip formed by pressing a heating heater supported by a heat insulating stay holder, a fixing member composed of a thin film and a pressure roller against each other. In this way, in the heating and fixing device which is provided with a paper discharge roller for fixing the unfixed image carried on the recording material and for conveying the recording material immediately after the fixing nip portion, A heating and fixing device characterized in that both ends are made faster than the center in the longitudinal direction or the conveyance direction of the discharge roller is directed outward at both ends.