JPH11316507A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent generation of a film guide rib mark, in a film heating system device. SOLUTION: The heating device is provided with a fixed/supported heating body 2 and a film 3 whose inside slides together with the heating body 2 and outside comes into contact with a material to be heated P and moved together with it and constituted so that the material to be heated P is heated by heat from the heating body 2 through the film 3. In such a case, a film guide 1 supporting the film 3 from the inside consists of at least two or more parts 1a (1c, 1e) and 1f. The positions in the longitudinal direction of the ribs 1g and 1j supporting the film 3 of the film guide 1 are different on the upstream and downstream sides.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a film heating type heating device and an image forming apparatus provided with the heating device as an image heating device or a heat fixing device.

[0002]

2. Description of the Related Art Conventionally, in an image forming apparatus such as an electrophotographic copying machine, a printer, and an electrostatic recording apparatus, the surface of a recording material (transfer material sheet, electrostatic recording paper, electrofax paper, printing paper, etc.) is used. As a fixing device (fixing device) for heating and fixing an unfixed image (toner image) formed and supported by an appropriate image forming process means on a surface of a recording material as a permanent fixed image, a heat roller type device is often used. ing.

[0003] This is basically composed of a heating roller (fixing roller) as a heating rotator and an elastic pressure roller as a pressing rotator brought into pressure contact with the heating roller. A recording material on which an unfixed image is formed and carried is introduced into a fixing nip portion (heating nip portion) which is a pressing nip portion of the roller, and the fixing nip portion is conveyed through the fixing nip portion so that heat from the heating roller and fixing are performed. The unfixed image is fixed by heat and pressure as a permanent fixed image on the surface of the recording material by the pressing force of the nip portion.

Recently, a heating device of a film heating system has been put into practical use as a heating fixing device in an image forming apparatus.

This is described, for example, in Japanese Patent Application Laid-Open No. 63-313182.
JP-A-2-1577872, JP-A-4-44072
Nos. 75-44083, 4-204980-204
No. 984, etc., a fixedly supported heating element, a heat-resistant film that slides on the heating element, and a fixing nip section (heating nip section) that is a press-contact nip section between the heating element and the heating element. And a pressure member for forming an unfixed image as a material to be heated is introduced between the film and the pressure member in the fixing nip portion, and the recording material is introduced together with the film. The fixing nip is passed through the fixing nip so that the unfixed image is fixed on the surface of the recording material by heat and pressure with the heat from the heating body via the film and the pressing force of the fixing nip. Further, for example, as an image heating device for heating a recording material carrying an image to improve the surface properties such as gloss, an image heating device for a hypothetical deposition process, and other devices for heating a sheet-shaped heating material. Can be widely used.

In such a heating apparatus of the film heating type, a linear heating element having a low heat capacity such as a so-called ceramic heater can be used as a heating element, and a thin film having a low heat capacity can be used as a film. As the temperature rises, the rise of the fixing nip to the predetermined temperature can be made quicker, so that it is not necessary to heat the heating element during standby, and the recording material as the material to be heated can be quickly removed. Even when the recording material passes, the heating element can be heated to a predetermined temperature until the recording material reaches the fixing nip portion, which is the fixing portion, and compared with other contact heating type devices such as a heat roller type. In addition, power saving and shortening of the wait time (quick start property) are possible, and an on-demand fixing device (film-type on-demand fixing device) can be configured.

The film heating type heating device uses an endless belt or a cylindrical film as a film driving system, and a driving roller is disposed on the inner peripheral side of the film. And a driving system in which the film is stretched and stretched by applying tension to a plurality of members including the above, and the film is rotationally driven by a driving roller, and the film is loosely fitted outside the film guide (tensionless), and the film is sandwiched. There is a pressing rotary member driving method in which a film is driven to rotate with respect to the pressing rotary member by driving a pressing rotary member as a pressing member that forms a pressure contact nip portion with the heating member.

[0008] Since the latter device for driving the rotating body for pressurization requires fewer parts than the former device, etc., the latter device for driving the rotating body for pressurizing has recently been adopted. Many.

FIG. 5 shows a schematic configuration of a conventional example of a heating / fixing apparatus of a film heating type / rotating body driving type / tensionless type. (A) is a schematic cross-sectional view of the device, and (b) is a front view of a film guide.

Reference numeral 1 denotes an elongated film guide (film guide member, stay) having a substantially semicircular trough-shaped cross section, which is a heat-resistant and electrically insulating rigid member capable of withstanding a high load.

Reference numeral 2 denotes a so-called ceramic heater (hereinafter abbreviated as a heater) as a heating element.
Groove 1b provided along the longitudinal direction of the member substantially at the center of the lower surface of
It is a thin and horizontally long member that is fitted and fixedly supported with its front side exposed downward.

Reference numeral 3 denotes a cylindrical heat-resistant film (hereinafter, referred to as a fixing film) as a heating rotator, which is loosely formed with a margin in the circumference of the film guide 1 including the heater 2. The film guide 1 supports the fixing film 3 from the inside.

Reference numeral 4 denotes a pressure roller as a pressure rotating body (pressure member), which comprises a metal core 4a, an elastic layer 4b, and an outermost release layer 4c. A fixing nip portion (heating nip portion) N, which is a press-contact nip portion, is formed by pressing the fixing film 3 against a downward surface of the heater 2 fixedly supported on the lower surface side of the film guide 1 with a predetermined pressing force by a spring. Is formed.

The pressure roller 4 is driven to rotate in a counterclockwise direction indicated by an arrow by a driving means M (a rotary member driving system for pressure).
A rotational force acts on the fixing film 3 by the frictional contact between the outer surface of the roller 4 and the outer surface of the fixing film 3 at the fixing nip portion N due to the rotational driving of the pressure roller 4. Heater 2 at fixing nip N
Clockwise as indicated by the arrow while sliding in close contact with the downward surface of
Then, the outer periphery of the film guide 1 is driven to rotate by a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 4.

In this case, the cylindrical fixing film 3 which is driven to rotate around the outer periphery of the film guide 1 has a fixing nip portion N having a peripheral length and a fixing film portion other than the fixing film portion in the vicinity of the fixing nip portion N. Not in the state).

Thus, the pressure roller 4 is driven to rotate, and the cylindrical fixing film 3 is accordingly moved by the film guide 1.
Of the fixing nip portion N is energized by the heater 2 and the temperature of the fixing nip portion N rises to a predetermined level by the heat generated by the heater 2, and the temperature of the fixing nip portion N is controlled.
A recording material P on which an unfixed image (toner image) t is formed and supported is introduced, and the unfixed image-bearing surface side of the recording material P is brought into close contact with the outer surface of the fixing film 3 in the fixing nip portion N. Together with the fixing nip portion N.

In the process of nipping and transporting the recording material, the heat of the heater 2 is applied to the recording material via the fixing film 3, and the unfixed image t on the recording material P is heated and pressed.

When the recording material P passes through the fixing nip portion N, the recording material P is conveyed from the outer surface of the fixing film 3 with a curvature separated.

The film guide 1 has, in a transverse section, a film guide main body portion 1a having a heater insertion groove 1b provided at a substantially central portion of a lower surface thereof along the longitudinal direction of the member; An upstream film guide portion 1c and a downstream film guide portion 1d provided on the main body portion 1a on both sides on the upstream side and the downstream side in the rotation direction, respectively; and • an upstream film guide portion 1c and a downstream film guide portion 1d. Each of the portions 1c and 1d is composed of a plurality of ribs 1e and the like provided at predetermined intervals along the length of each of the portions 1c and 1d.

The rib 1e has an arc shape along the inner circumferential direction of the cylindrical fixing film, and supports the inner surface of the fixing film.

The film guide main body portion 1a, upstream film guide portion 1c, downstream film guide portion 1d, rib 1e, etc. constituting the film guide 1 are integrally molded products of the same material as a whole.

[0022]

Incidentally, in the conventional fixing apparatus of the film heating type, it is necessary to reduce the heat capacity in order to provide the on-demand property, and therefore, there are the following problems.

That is, in an image forming apparatus using a film heating type fixing device, the fixing nip N
Heat is directly applied to the unfixed image (toner image) on the recording material P such as paper from the heater 2 via the fixing film 3,
The heat of the fixing film 3 is partially removed by the film guide 1 that supports the fixing film 3 from the inside. Since the fixing film 3 has a small heat capacity unlike a fixing roller in a heat roller type apparatus, the temperature of the portion from which heat has been taken is reduced and the fixing film 3 reenters the fixing nip N. However, due to this temperature variation, the fixing nip N In some cases, the amount of heat may be insufficient and the amount of heat may be excessive, so that the degree of fixing may be changed, and fixing unevenness may occur to cause unevenness on an image.

This problem has been conspicuous when the on-demand fixing device of the film heating type is developed into a fixing device having a high process speed, and is particularly remarkable when the fixing device is at room temperature.

More specifically, comparing the temperature of the fixing film portion corresponding to the position on each rib 1e of the film guide 1 with the temperature of the fixing film portion corresponding to the position between the ribs 1e, 1e, the former temperature is It becomes lower than the latter temperature.

This is because the fixing film portion corresponding to the position on each rib 1e of the film guide 1 is deprived of heat by the rib 1e by contact with or approaching the rib 1e. This is because the fixing film portion corresponding to the position between 1e is a space where the film does not contact anything between the ribs 1e and 1e, and there is no heat loss due to contact with the rib 1e or approach to the rib 1e.

Then, the temperature of the fixing film portion corresponding to the position on each rib 1e of the film guide 1 and each rib 1e
If the temperature difference from the temperature of the fixing film portion corresponding to the position during 1e is relatively large, the amount of heat is partially insufficient or excessive in the fixing nip portion N due to temperature variation on the surface of the fixing film, and the fixing is performed. And the degree of fixing may change, and fixing unevenness may occur to cause unevenness on the image.

FIG. 6 schematically shows an image in which a "rib mark" which is one of such phenomena is generated. The rib trace is a phenomenon in which, when a solid black image is printed, fixing unevenness due to a temperature difference of the fixing film in the image portion corresponding to the position of the rib 1e of the film guide 1 of the fixing device becomes streak-like density unevenness. . In FIG. 6, ta is a rib trace portion, and a solid black image is shining (blackish) only in an image portion corresponding to the position of the rib 1e of the film guide 1,
Black becomes darker than the image portion corresponding to the position between the ribs 1e.

Therefore, the present invention relates to a film heating type heating device, which is capable of preventing uneven heating of a material to be heated due to the film surface temperature variation by reducing the film surface temperature variation. It is an object of the present invention to prevent the amount of heat from being partially insufficient or excessive in the fixing nip portion N due to the temperature variation on the film surface, thereby preventing the occurrence of fixing unevenness and unevenness such as rib marks on an image.

[0030]

SUMMARY OF THE INVENTION The present invention is a film heating type heating device having the following constitution, and an image forming apparatus provided with the heating device as an image heating device or a heat fixing device.

(1) A fixedly supported heating element, and a film having an inner surface sliding with the heating element and an outer surface contacting and moving with the material to be heated, and the film is moved from the heating element through the film. In a heating device for heating a material to be heated by heat, a film guide member for supporting a film from an inner surface is provided with at least two members.
A heating device comprising at least parts.

(2) The heating device according to (1), wherein the longitudinal positions of the ribs for supporting the film of the film guide are different in the upstream and downstream directions.

(3) The heating device according to (1) or (2), further including a pressure member that forms a heating nip portion of the material to be heated by mutual pressure contact with the heating body with the film interposed therebetween.

(4) The heating device according to any one of (1) to (3), wherein the film is a cylindrical member or an endless belt-like member.

(5) The heating device according to (3) or (4), wherein the pressing member is driven to rotate, and the film is moved by the rotation of the pressing member.

(6) The heating device according to any one of (1) to (5), wherein the material to be heated is a recording material carrying an image to be subjected to heat treatment or heat fixing.

(7) Any one of the above (1) to (6)
An image forming apparatus, comprising: an image heating device or a heat fixing device that heat-treats or heat-fixes an image carried on a recording material by using the heating device described in (1).

<Operation> By forming the film guide with two or more parts (hereinafter, referred to as two parts), it is possible to provide a plate member between the ribs for supporting the film of the film guide from the inner surface. Thus, the difference in the amount of heat taken by the film guide from the film portion between the rib and the rib can be reduced.

Further, by using two components, the heat capacity of the rib member on the upstream side of the nip can be reduced, and the amount of heat taken from the film can be reduced.

Further, by making the longitudinal positions of the ribs supporting the film different at the upstream and downstream, a large amount of heat is prevented from being taken away from the same position of the film.

By using two parts, separate members can be used for the film guide main body and the separate rib portion. That is, there is an advantage that the film guide main body portion can be made of a component having excellent heat resistance, and the separate rib portion can be made of a member having a small heat capacity or a member having a low heat resistance but a low cost.

As described above, with respect to the film heating type heating device, the temperature variation on the film surface is reduced,
Prevents uneven heating of the material to be heated due to temperature variations on the film surface.In the case of a heat fixing device, the amount of heat is partially insufficient or excessive in the fixing nip due to the temperature variation on the film surface, causing uneven fixing. As a result, it is possible to prevent unevenness such as rib marks on the image.

[0043]

DESCRIPTION OF THE PREFERRED EMBODIMENTS First Embodiment (FIGS. 1 and 2) (1) Example of Image Forming Apparatus FIG. 1 shows an image forming apparatus having a film heating type heating device according to the present invention as a fixing device. It is a schematic structure figure of an example. The image forming apparatus of this embodiment is a laser beam printer using a transfer type electrophotographic process.

Reference numeral 11 denotes a rotating drum type electrophotographic photosensitive member (hereinafter, referred to as a photosensitive drum) as an image carrier. OP
A layer of a photosensitive material such as C or amorphous silicon is formed on a cylindrical substrate such as aluminum or nickel. Then, it is rotationally driven at a predetermined peripheral speed (process speed) in the clockwise direction of the arrow.

During the rotation process, the photosensitive drum 11 is first uniformly charged to a predetermined polarity and potential by a charging roller 12 as a charging device.

Next, a laser beam scanning exposure L corresponding to a target image information pattern is received by a laser scanner 13 as an exposure device. As a result, an electrostatic latent image corresponding to the target image information pattern is formed on the surface of the rotating photosensitive drum 11.

The laser scanner 13 is turned ON / OFF in response to a time-series electric digital pixel signal of a target image information pattern sent from an external device such as a host computer (not shown).
The laser beam L that is turned off (intensity modulated) is output, and the uniformly charged surface of the rotating photosensitive drum 11 is scanned and exposed with the laser beam.

The electrostatic latent image formed on the surface of the rotating photosensitive drum 11 is visualized by developing the toner in the developing device 14. As a developing method, a jumping developing method, a two-component developing method, or the like is used, and in many cases, a combination of image exposure and reversal developing is used.

The toner image formed on the surface of the rotating photosensitive drum 11 is transferred to the transfer nip formed by the photosensitive drum 11 and the transfer roller 15 at a predetermined control timing. It is sequentially transferred to a material (transfer material) P. A predetermined transfer bias is applied to the transfer roller 15 from a power supply (not shown) at a predetermined control timing, and the toner image on the photosensitive drum 11 is transferred to the recording material P by the action of the transfer bias.

In the image forming apparatus of this embodiment, the cassette paper feeding mode from the paper feeding cassette 21 and the manual feed tray 2
7, the user can select the manual paper feed mode to feed the recording material.

In the case of the cassette sheet feeding mode, the recording materials P stacked and stored in the sheet feeding cassette 21
And one sheet separating member (not shown) separates and feeds the sheet,
Sheet path 23 → first sensor (rear end detection sensor) 24 →
Registration roller 25 → second sensor (registration sensor) 2
6, the paper is fed to the transfer nip at a predetermined control timing.

In the case of the manual paper feed mode, the recording material P inserted into the apparatus from the manual paper feed tray 27 is fed to the paper feed roller 28.
At a predetermined control timing through a path of sheet path 29 → first sensor (rear end detection sensor) 24 → registration roller 25 → second sensor (registration sensor) 26. Sent.

The size of the recording material is detected by the first sensor 24. The recording material size detection may be performed by the second sensor 26. The recording material P is supplied to the transfer nip by the registration roller 25 in synchronization with the toner image formed on the surface of the photosensitive drum 11.

The recording material P, which has received the transfer of the toner image at the transfer nip and has retained the toner image, is sequentially separated from the surface of the rotating photosensitive drum 11 and is conveyed to the heat fixing device 18 through the sheet path 17. Heating at the fixing nip of the fixing device
When the toner image is pressurized, the toner image is fixed on the recording material P to become a permanent image, and is discharged by a discharge roller 19 to a discharge tray 20 outside the apparatus.

On the other hand, the transfer residual toner remaining on the photosensitive drum 11 after the transfer of the toner image to the recording material P (after the recording material separation) is performed by the cleaning device 16.
The surface of the photosensitive drum 11 removed and cleaned from one surface is repeatedly subjected to image formation.

(2) Heat fixing device 18 FIG. 2A is a schematic cross-sectional view showing a schematic configuration of the heat fixing device 18, FIG. 2B is a front view of a film guide, and FIG.
FIG. 2 is a schematic cross-sectional view of a ceramic heater as a heating element.

The heating and fixing device 18 of this embodiment is the same as that of FIG.
As in the case of the above-mentioned heat fixing device, the heat fixing device is a film heating system, a rotating body driving system for pressurization, and a tensionless type. Constituent members and portions common to those of the heat fixing device of FIG. 5 are denoted by the same reference numerals, and description thereof will not be repeated. The heat fixing operation and principle of the apparatus 18 are the same as those of the apparatus shown in FIG.

A. Film guide 1 Film guide 1 is made of a heat-resistant, electrically insulating, rigid material capable of withstanding high loads, for example, liquid crystal poymer, PPS
(Polyphenylene sulfide), PAI (polyamide imide), PI (polyimide), PEEK (polyether ether ketone) and the like.

According to the present invention, the film guide 1
It is made into parts. This will be described later.

B. Ceramic Heater 2 The ceramic heater 2 as a heating element is as follows.
As shown in the cross-sectional model diagram of (c), ・ Long and thin ceramic substrate (heater substrate) with electrical insulation, heat resistance, and good thermal conductivity such as alumina (Al ₂ O ₃ )
2a. A current-generating layer 2b formed by printing a paste of a current-generating material such as silver-palladium on the surface side of the ceramic substrate 2a along the length of the substrate in a narrow band pattern by printing or the like. To ensure protection and insulation,
A glass coating layer 2c covering the surface of the ceramic substrate provided with the energizing heating element layer 2b. A chip thermistor 2d as a temperature detecting element provided on the back surface side of the ceramic substrate 2a.

Heat is generated by passing an AC current whose power is controlled from the power source S to the current-carrying heating element layer 2b. Temperature detection information of the chip thermistor 2d as a temperature detecting element is input to the control circuit 30, and the control circuit 30 operates the heater driving means 31 based on the input information to switch the power supply S from the power supply heating element layer 2b.
To properly control the power to More specifically, a change in temperature within a time when power supply to the heater 2 is turned OFF or ON for a certain period of time when paper is not passed is detected by the chip thermistor 2d, and a target temperature of the heater 2 is determined based on the detection result. Thus, the heater driving means 31 is controlled to control the power to the heater 2 to maintain the heater temperature at the target temperature (print temperature).

C. Fixing Film 3 The fixing film 3 has a total thickness of 100 μm or less in order to reduce the heat capacity and improve the quick start property.
Heat resistance is preferably 40 μm or less and 20 μm or more.
PTFE, PFA, PP with releasability, strength, durability, etc.
S or a single-layer film, or polyimide, polyamide imide, PEEK, PES
It is a composite layer film coated with PFA, FEP, and the like as a mold release.

D. Pressure Roller 4 The pressure roller 4 as a pressure member has an elastic layer 4b formed of heat-resistant rubber such as silicone rubber or a sponge elastic layer 4b formed by foaming silicone rubber on a cored bar 4a. Rotating body, PFA, PTF on elastic layer 4b
A heat-resistant release tube layer 4c made of a fluorine resin such as E or FEP is formed.

The outer diameter of the pressure roller 4 in this embodiment is 2
0.0 mm, and the outer diameter of the cored bar 4a is 13 mm.

The pressure roller 4 is pressed by a spring (not shown) through the fixing film 3 to the lower surface of the ceramic heater 1 as a heating element which is fitted and held in the groove 1b on the lower surface of the film guide 1 and has a predetermined width. 5, is driven to rotate by a drive system M in the same manner as in the apparatus of FIG. 5, and the outer surface of the roller 4 and the outer surface of the fixing film 3 are driven by the rotation of the pressure roller 4. A rotational force acts on the fixing film 3 due to the frictional contact between the fixing film 3 and the fixing film 3 at the fixing nip N, and the inner surface of the fixing film slides in the fixing nip N in close contact with the downward surface of the heater 2. The film guide 1 is driven to rotate around the outer periphery of the film guide 1 at a peripheral speed substantially corresponding to the rotational peripheral speed of the pressure roller 4 in the direction a.

(3) Making the film guide 1 into two parts The film guide 1 needs to withstand the high temperature by directly attaching the heater 2 thereto. When the non-sheet passing portion is created by printing small size paper, the temperature of the film guide 1 is partially 3
Close to 00 degrees. Therefore, the film guide 1 in the conventional apparatus shown in FIG.
CP) (product with a heat distortion temperature of 335 degrees, trade name Econole E,
E5008 grade, Sumitomo Chemical).

As shown in FIGS. 2 (a) and 2 (b), the film guide 1 in this embodiment has a heater inserted along the longitudinal direction of the member substantially at the center of the lower surface in the cross section of the film guide 1. The film guide portion 1f on the upstream side in the film rotation direction from the film guide body portion 1a provided with the groove portion 1b is referred to as the film guide body portion 1a and the film guide portion 1d on the downstream side in the film rotation direction from the film guide body portion 1a. -It is a separate part (separate part) from 1e.

Then, the film guide body portion 1a and the downstream film guide portions 1d, 1
e is formed using the same heat-resistant liquid crystal polymer (LCP) as described above, but the upstream film guide portion 1f, which is a separate component, has a lower heat resistance than P.
PS (Tonen, HT1301 grade, heat deformation temperature 270
Degrees).

Since the upstream film guide portion 1f, which is a separate component, does not directly touch the heater 2, the heat resistance of the portion which touches the fixing film at 150 degrees is sufficient.

The upstream film guide portion 1f, which is a separate component, is a horizontally long plate-like member, and has on its outer surface a plurality of longitudinal convex ribs 1g at predetermined intervals along the length of the member. Let me do it. This convex rib 1g is about 1m in width.
m, height about 1 mm.

The shapes of the downstream film guide portions 1d and 1e are the same as those of the conventional film guide 1 shown in FIG. 5, and the rib 1e is a rib having a bone shape (rod shape).

However, the positions of the ribs along the longitudinal direction of the film guide are different between the upstream film guide portion 1f and the upstream film guide portions 1d and 1e as shown in FIG.

The film guide main body portion 1a and the downstream film guide portions 1d and 1e, which are integrally formed with each other, and the upstream film guide portion 1f, which is a separate component, are respectively fixed to the apparatus main body member by supporting means (not shown). It is mounted and supported with the arrangement relationship maintained.

Here, the fixing device 18 of this embodiment in which the upstream film guide portion 1f of the film guide 1 is formed as a separate component as described above, and the film guide 1 of FIG. 5 are not formed as two components. With respect to the conventional device (comparative example), the fixing film temperature was measured in the vicinity of the fixing nip portion N on the upstream side in the film rotation direction. The measuring method was such that a thermocouple was brought into contact with the surface of the fixing film, and the temperature was measured while printing. Table 1 shows the results.

[0075]

[Table 1] Table 1 shows the temperature of the fixing film immediately before the leading edge of the paper enters the fixing device when the first and tenth sheets are printed from the room temperature of the fixing device. The temperature was measured for the fixing film portion at the rib position (on the rib) of the film guide 1 and the fixing film portion between the ribs. Here, between ribs means between ribs on the upstream side.

As is clear from Table 1, in the first sheet, the temperature difference between the fixing film portion on the rib and the fixing film portion between the ribs was 1 in the comparative example.
In contrast to 5 ° C., the temperature was 8 ° C. in this embodiment. On the tenth sheet after printing, the temperature difference between the fixing film portion on the rib and the rib was 15 ° C. in the comparative example, but was 5 ° C. in the present example.

In the comparative example, between the ribs 1e
The fixing film is in a space where none of the fixing films come into contact with each other, and the fixing film receives heat only from the rib 1e to the film guide. In this embodiment, however, there is a flat plate between the ribs 1g and 1g. Is absorbed by the flat plate not only in the portion of the rib 1g but also in the portion between the ribs 1g and 1g.
The difference is smaller between 1 g.

Further, with respect to the apparatus of this embodiment and the apparatus of the comparative example, plain paper (thickness: 64 g / m ² ) was continuously printed in solid black from room temperature to check the occurrence of rib marks. Table 2 shows the results.

[0079]

[Table 2] In the comparative example, traces of the ribs are conspicuous from the appearance of the first sheet, and are still evident even on the tenth sheet. Here, the extent of the rib trace gradually improves as the film guide 1 warms up as a whole.

On the other hand, in the present embodiment, it can be seen that there is a remarkable improvement effect at a level where the first sheet is faintly recognized, and it disappears completely on several sheets.

As described above, the film guide 1 for supporting the fixing film 3 from the inner surface is composed of at least two parts, so that the main body portions 1a, 1d, and 1 of the film guide 1 are formed.
For e and the separate part 1f, it is possible to use another material which is optimal for each. Thereby, since the heat resistance may be low for the separate portion 1f, a low-cost component can be used.

Further, a plate member can be provided between the ribs 1g for supporting the fixing film of the film guide 1 from the inner surface, and the film guide is provided from the fixing film portion on the rib 1g and between the ribs 1g. The difference in the amount of heat deprived of the fixing film can be reduced, the temperature variation on the surface of the fixing film is reduced, and the amount of heat is partially insufficient or excessive in the fixing nip portion N. Unevenness can be prevented.

<Second Embodiment> (FIG. 3) In this embodiment, the fixing device 18 of the above-described first embodiment is provided as a separate part in the upstream film guide portion 1f of the film guide 1. FIG. 3 shows the vertical convex rib 1g thus set.
It is changed to the one in the oblique direction as shown in FIG. This obliquely convex rib 1g has a width of 1 mm and a height of 1 mm.

The other components and materials are the same as those of the first embodiment.

The occurrence of rib marks was also examined for the apparatus of this embodiment. Table 3 shows the results.

[0086]

[Table 3] In the apparatus of this embodiment, the effect of preventing the rib trace was further enhanced, and no rib trace was generated even when the first sheet was started from room temperature.

<Third Embodiment> (FIG. 4) In this embodiment, as shown in FIG. 4, in the fixing device 18 of the first embodiment, a substantially central portion of the lower surface is formed along the length of the member. Both the upstream and downstream film guide portions 1f and 1i in the film rotation direction are separate parts from the film guide main body portion 1a provided with the heater fitting groove 1b.

The downstream film guide portion 1i, which is a separate component, has a horizontally long plate-like member like the upstream film guide portion 1f, and has a plurality of outer surfaces provided at predetermined intervals along the length of the member. The book has ribs 1j.

The upstream and downstream film guide portions 1f
And 1i, the longitudinal positions of the ribs 1g and 1j are different between upstream and downstream.

In this embodiment, the ribs 1g and 1j of the film guide portions 1f and 1i on the upstream side and the downstream side are obliquely arranged as in the second embodiment (FIG. 3). In the case of the oblique rib shape, the positions of the ribs 1g and 1j are not so affected, but the rib positions are not biased to a specific portion of the film.

The other device configuration is the same as in the above embodiment. Film guide body 1a and separate parts 1f and 1i
Were the same as in the above examples.

The occurrence of rib marks was also examined for the apparatus of this embodiment. When the same experiment as in the second example was performed, the same result as in Table 3 was obtained.

Further, the ribs 1g and 1j of the film guide portions 1f and 1i on the upstream side and the downstream side can be formed as vertical convex ribs as in the apparatus of the first embodiment. However, it is preferable that the positions of the ribs 1g and 1j are different between the upstream and the downstream.

<Others> 1) In the present invention, the heating device of the film heating type is
As a film driving method, an endless belt or a cylindrical film is used for the film, a driving roller is disposed on the inner peripheral surface side of the film, and tension is applied to the film between a plurality of members including the driving roller. Alternatively, a driving system in which the film is stretched and suspended and the film is rotationally driven by a driving roller may be used.

2) As a means for protecting the ceramic heater as a heating element, a safety element, for example, a temperature fuse or a thermoswitch is interposed in series in the power supply line to the AC line of the heater and brought into contact with or close to the heater. It is good to arrange.

3) The heating element is not limited to a ceramic heater. For example, an electromagnetic induction heating member such as an iron plate or another heater structure may be used.

4) The pressing member need not be a roller.
For example, it may be a rotating belt member.

5) The reference for transporting the material to be heated may be the one-side transport reference or the two-side transport reference.

6) In the present invention, the heating device is not limited to the heating and fixing device of the embodiment, but may be an image heating device for heating a recording material carrying an image to improve the surface properties such as gloss.
Means and devices for heating the material to be heated, such as an image heating device to be assumed, a heating and drying device for the material to be heated, and a heating laminating device, are widely included.

[0100]

As described above, according to the present invention, for a film heating type heating device, a film guide is composed of two or more parts (two parts) to support the film of the film guide from the inner surface. A plate member can be provided between the ribs, and the difference in the amount of heat taken by the film guide from the film portion between the ribs and the ribs can be reduced.

Also, the heat capacity of the rib member on the upstream side of the nip can be reduced by using two parts, and the amount of heat taken from the film can be reduced.

Further, by making the longitudinal positions of the ribs supporting the film different at the upstream and downstream sides, it is possible to prevent a large amount of heat from being taken from the same position of the film.

By forming two parts, separate members can be used for the film guide main body and the separate rib portion. That is, there is an advantage that the film guide main body portion can be made of a component having excellent heat resistance, and the separate rib portion can be made of a member having a small heat capacity or a member having a low heat resistance but a low cost.

As described above, with respect to the film heating type heating device, the temperature variation on the film surface is reduced,
Prevents uneven heating of the material to be heated due to temperature variations on the film surface.In the case of a heat fixing device, the amount of heat is partially insufficient or excessive in the fixing nip due to the temperature variation on the film surface, causing uneven fixing. As a result, it is possible to prevent unevenness such as rib marks on the image.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an image forming apparatus according to a first embodiment.

2A is a schematic cross-sectional view showing a schematic configuration of a heat fixing device according to the first embodiment, FIG. 2B is a front view of a film guide, and FIG. 2C is a cross section of a ceramic heater as a heating element. Surface model drawing

FIG. 3 is a front view of a film guide of a heat fixing device according to a second embodiment.

FIG. 4 is a schematic cross-sectional view showing a schematic configuration of a heat fixing device according to a third embodiment.

FIG. 5A is a schematic cross-sectional view showing a schematic configuration of a conventional example of a film heating system, a rotating body driving system for pressurization, and a tensionless type heat fixing device, and FIG. 5B is a front view of a film guide.

FIG. 6 is a diagram schematically showing an image in which “rib marks” have occurred.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Film guide 1a Film guide main body part 1b Heater fitting groove part 1c ・ 1d Upstream and downstream film guide parts 1e Bone-shaped (rod-shaped) ribs 1f ・ 1i Upstream and downstream film guide parts 1g ・ 1j as separate parts Rib 2 Heating element (ceramic heater) 3 Fixing film 4 Pressure roller

Claims (7)

[Claims] 1. A fixedly supported heating element, and a film in which an inner surface slides with the heating element and an outer surface contacts and moves with the material to be heated, and the heat from the heating element via the film is provided. A heating device for heating a material to be heated according to (1), wherein the film guide supporting the film from the inner surface is constituted by at least two parts. 2. The heating device according to claim 1, wherein the ribs for supporting the film of the film guide have different longitudinal positions in the upstream and downstream directions. 3. The heating device according to claim 1, further comprising a pressure member that forms a heating nip portion of the material to be heated by being mutually pressed against a heating body with a film interposed therebetween. 4. The heating device according to claim 1, wherein the film is a cylindrical member or an endless belt-like member. 5. The heating device according to claim 3, wherein the pressing member is driven to rotate, and the film is moved by the rotation of the pressing member. 6. The heating apparatus according to claim 1, wherein the material to be heated is a recording material carrying an image to be subjected to a heat treatment or a heat fixing. 7. An image heating device or a heat fixing device for heating or thermally fixing an image carried on a recording material, wherein the heating device according to claim 1 is provided. Image forming apparatus.