JPH06194977A - Heating device - Google Patents

Abstract

PURPOSE:To provide a heating device for preventing lubricant from infiltrating to the contact electrode of a heater and a film surface and having a system for sliding a film in contact with a heating body. CONSTITUTION:As to the heating device for pressing a pressing member 6 contact with the fixed and supported heating body 3 through the film 2, introducing a material to be heated P between the film 2 and the pressing member 6 in accordance with the traveling of the film 2, giving heat energy to the material to be heated P from the heating body 3 through the film 2 and interposing the lubricant 9 between the heating body 3 and the surface of the film 2 coming into contact with the heating body, a dam-shaped, or groove-shaped part, or a member is installed near the electric contact of the heating body 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device of the type which applies heat energy to a material to be heated such as a recording material through a heat resistant film.

This type of heating apparatus is an image heating apparatus in an image forming apparatus such as an electrophotographic copying machine, a printer and a fax machine, that is, a resin meltable by heating by an image forming process means such as electrophotography, electrostatic recording and magnetic recording. Corresponding to the target image information formed by the direct method or the indirect (transfer) method on the surface of the recording material (electrofax sheet, electrostatic recording sheet, recording material sheet, printing paper, etc.) using the toner composed of The unfixed toner image can be utilized in an image forming apparatus that performs heat fixing processing as a permanently fixed image on the surface of a recording material carrying the image.

Further, it is not limited to the image forming apparatus, but it can be widely used as means and apparatus for heat-treating an image carrier such as an apparatus for heating a recording material carrying an image to modify the surface property.

[0004]

2. Description of the Related Art Conventionally, a heating body (thermal heater, hereinafter referred to as "heater") directly fixed to a metal or resin holder, and a heat-resistant film (fixing film) conveyed while being pressed against the heater. And a pressurizing member that pressurizes the recording material as a material to be heated in close contact with the heater through the film, and by applying heat from the heater to the recording material through the film, the recording material is formed and carried on the surface of the recording material. There has been proposed a heating device of a system (film heating system) for heating and fixing an unfixed image on a recording material surface.

The heating device disclosed in, for example, Japanese Patent Laid-Open No. 63-313182, which is a proposal of the present applicant, belongs to this. This apparatus comprises a thin heat-resistant film (sheet), a driving means for moving the film, a heater fixedly supported on one side of the film with the film at the center, and a heater on the other side. It has a pressing member which is arranged so as to face the heater, and which makes the visible image bearing surface of the recording material, which is an image-fixed material, to be in close contact with the heater via the film. At least during image fixing, the film travels at the same speed in the forward direction as the recording material to be image-fixed conveyed and introduced between the film and the pressure member, and is heated by a heater sandwiching the running moving film. It passes through a fixing nip portion as a fixing point formed by pressure contact with a pressure member. As a result, the surface of the recording material on which the visible image is carried is heated by the heater through the film, and the visible image (unfixed toner image) is applied with heat energy to be softened / melted, and then the film is passed through the fixing point to form a film. The recording materials are separated at the separation point.

In such a film heating system,
A low heat capacity heating element can be used as the heater. Therefore, it is possible to save power and shorten the wait time (quick start) as compared with a conventional heating device such as a heat roller system or a belt heating system which is a contact heating system. In addition, it has an advantage that various drawbacks of the conventional heating method can be solved, and is effective.

[0007]

In a film heating type heating device, as a driving means for the film, an endless film which is always tensioned by applying tension to the entire circumference is used as a driving roller from the inside of the film. Driven by, and as an improved version of it, part of the circumference of the film is always tension-free (a state where no tension is applied), and the driving means for the film is the rotational drive of a pressure member provided outside the film. Two types have been proposed, one that is obtained from force (tension-free film heating method).

In such a film heating type heating device, when the heating device is an image fixing device, the film is sandwiched between the heating body and the pressing member in consideration of the fixing property and the offset property. The fixing nip portion is pressurized with a certain amount of force or more and is high in temperature. As a result, the slidability between the film and the heater deteriorates, and when the frictional force becomes larger than the frictional force between the film and the driving roller, the film cannot run and move. Especially in the case of the tension-free film heating method, the slidability between the film and the heater deteriorates, and if this becomes greater than the frictional force between the film and the recording material carrying the unfixed image, the film travels. However, there is a problem in that the unfixed image is disturbed due to the occurrence of slip between the film and the recording material.

Therefore, the present applicant has previously proposed a method of solving the above-mentioned problem by interposing a lubricant between the film and the heater.

However, when a conventional tubular endless film is used, as the number of times of use increases, the lubricant inside the film travels along the surface of the heater and penetrates into the contact at the end of the heater. In some cases, the heater does not generate heat due to a defect, or the temperature control is disturbed in the case of a heater in which a contact of a temperature detecting element for temperature control is provided on the heater.

Further, the lubricant on the inside of the film comes out so as to wrap around the outside of the film and adheres to the surface of the film. Therefore, depending on the lubricant, the recording material may be soiled or an offset may be generated. Further, in the tension-free film heating type heating device, since the frictional force between the surface of the film and the recording material is reduced, there is a problem that slip is likely to occur.

According to the present invention, in a film heating type heating device in which a lubricant is interposed between a film and a heater, a contact electrode is provided between a heating surface (a lubricant application surface) of the heater and a contact electrode. It is a first object of the present invention to provide a heating device capable of preventing the lubricant from entering and preventing contact failure due to the lubricant entering the contact.

The present invention also provides the above heating device,
By preventing the lubricant inside the film from wrapping around to the film surface (outside), it is possible to prevent stains on the recording material due to the lubricant, offset, and slip between the film and recording material in the tension-free film method. The purpose is.

[0014]

According to the present invention, the first object is to bring a pressure member into pressure contact with a fixedly supported heating body through a film, and to move the film while the material to be heated is moved. Is introduced between the film and the pressure member, heat energy is applied to the material to be heated from the heating body through the film, and between the heating body and the surface where the film contacts the heating body. In the heating device in which the lubricant is interposed, the first invention is achieved by providing a weir-shaped or groove-shaped portion or member near the electric contact portion of the heating body.

A second object is to bring the film into contact with and slide it against a fixedly supported heating element, and to bring a material to be heated into close contact with the surface of the film opposite to the heating element so that the film together with the heating element. A heat energy is applied to the material to be heated from the heating body through the film by moving through the position, and a lubricant is interposed between the heating body and the surface where the film contacts the heating body. The present invention is achieved by the second invention in which the heating device is provided with a portion having a shape for preventing the lubricant from moving to the heated material contact surface of the film, at the end portion of the film.

[0016]

According to the present invention, according to the first aspect of the present invention, even if the lubricant moves across the heater surface, the dam-like or groove-like portion or member provided in the vicinity of the electric contact is provided. Further movement is blocked and does not reach the electrical contacts.

Next, according to the second aspect of the invention, a portion for preventing the lubricant from moving to the contact surface of the material to be heated of the film is provided at the end portion of the film, and the lubricant is provided on the surface of the film. It will not adhere.

[0018]

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

<First Embodiment> FIG. 2 is a cross-sectional view showing a schematic structure of a tension-free film heating type heating apparatus as a first embodiment of the present invention. In this embodiment, this heating device is used as an image heating and fixing device of the image forming apparatus.

In FIG. 2, reference numeral 1 denotes a heat-resistant resin-made laterally long stay extending in the axial direction, which serves as an inner surface guide member of the endless heat-resistant film 2 described below.

2 is an endless heat-resistant film,
The stay 1 including the heater 3 is externally fitted. The inner peripheral length of the endless heat-resistant film 2 is larger than the outer peripheral length of the stay 1 including the heater 3 by, for example, about 3 mm. Therefore, the film 2 has a peripheral length longer than that of the stay 1 including the heater 3. It fits loosely with a margin.

In order to reduce the heat capacity of the film 2 and improve the quick start property, the film thickness is preferably 100 μm or less in total, and PTFE / PFA having heat resistance, releasability, strength, durability, etc. It is preferable to use a single layer such as FEP or a composite layer film in which the outer peripheral surface of polyimide, PEEK, PES, PPS or the like is coated with PTFE, PFA, FEP or the like. In this example, the outer peripheral surface of polyimide was coated with PTFE.

The heater 3 extends in the axial direction at a substantially central portion of a substrate made of alumina or the like, and has, for example, A
Electrical resistance material (heating element) such as g / Pd (silver palladium)
4 is formed to have a thickness of 10 μm and a width of 1 to 3 mm by screen printing or the like, and a protective layer 5 having a coat of glass, fluororesin or the like is formed thereon. The contact electrodes 10 for supplying electric power to the heating element 4 are provided so as to be located on both front and back surfaces of one end portion in the longitudinal direction of the heating element 4. This simplifies the device by supplying power to one side of the one end. If this contact electrode is provided on the same surface at both ends, the width of the heater 3 must be made large in order to secure a sufficient size of the contact electrode and a sufficient distance between the contacts for safety, which is an advantage of the present invention. This is because the power saving and the shortening of the wait time using the low heat capacity heating element are impaired. In the present embodiment, a through hole is formed in the end of the heating element from the end of the heater 3 on the side where there is no contact electrode for power supply in the heater 3, and the screen on the back surface of the heater (the surface not contacting the film) is formed. Power is supplied by a power supply pattern 11 formed by printing or the like.

Reference numeral 6 in the drawing denotes a film pressure roller as a rotating body for driving the film 2 by forming the fixing nip portion N by sandwiching the film 2 with the heater 3, and a central shaft 7 and this shaft. And a roller portion 8 formed as a heat-resistant rubber elastic body having a good releasability such as an external silicone rubber, and the end portion of the central shaft 7 is driven by a driving means (not shown) to rotate in a counterclockwise direction indicated by an arrow. Is driven to rotate. Pressure roller 6
The endless heat-resistant film 2 is also rotationally driven in the clockwise direction as indicated by the arrow by rotating.

When the endless heat-resistant film 2 is not driven, most of the remaining portion except the portion sandwiched between the nip portion N of the heater 3 and the pressure roller 4 is tension-free. ing.

When the pressure roller 6 is rotationally driven, a moving force is applied to the film 2 at the nip portion N by a frictional force between the film 2 and the rotary pressure roller 6, and the film 2 has a speed substantially equal to the rotational peripheral speed of the pressure roller 6. The back surface of the film is the surface of the heating element 3 (=
It is rotationally driven clockwise while sliding on the surface of the protective layer 5. When the film is driven, tension is applied to the film only at the nip portion N and on the upstream side of the nip portion N in the moving direction of the film, and only at the portion between the nip portion and the film inner surface guide portion near the nip portion.

In the state in which the film is driven and the heating element 4 of the heater 3 is energized, the recording material P carrying the unfixed toner image T is formed between the rotating film 2 in the nip portion N and the rotating pressure roller 6. When introduced with the image bearing surface facing upward, the recording material P passes through the nip portion N together with the film 2, and the thermal energy of the heater 3 which is in contact with the back surface of the film at the nip portion N causes the film 3 to pass through the film. The toner image T is applied to the recording material P via the toner 2 and heat-fixed.

The lower surface of the heater 3 in the fixing nip portion N,
That is, the frictional resistance between the film 2 and the heater 3 is reduced between the protective layer 5 of the heater 3 and the back surface (inner surface) of the fixing film 2, that is, the surface of the recording material P opposite to the side in contact with the toner image T. A lubricant 9 is interposed in order to achieve this.

The lubricant 9 does not substantially disappear or deteriorate even when used at high temperatures, and does not attack other contact members such as the stay 1 made of heat-resistant resin or the like. It is necessary. According to the experiments by the inventors,
Fluorine grease as the lubricant 9 (for example, DEMUNUM GREASE L-6 manufactured by Daikin Industries, Ltd.)
5 etc.) or silicone oil may be used.

In this embodiment, the heater 3 is provided with a groove 12 having a depth of 2 mm and a width of 2 mm inside the contact electrode 10 as shown in FIG. The groove 12 is located at a position where the film 2 does not reach in any case, and the lubricant 9 on the inner surface of the film is not touched directly. The groove 9 can prevent the lubricant 9 transmitted on the surface (protective layer 5) of the heater 3 from entering the contact electrode portion 10. According to the experiments by the present inventors, the inner diameter is 25 m.
m, film 2 with a length of 230 mm in the axial direction, width of 8
The optimum grease amount is 50 mg to 150 mg when the heater 3 having a length of mm and a length of 260 mm in the axial direction is used. For this amount of grease, the groove 3 having a width of 2 mm and a depth of 2 mm is sufficient. Even if the heat treatment of 200,000 sheets was performed, the groove 12 was not completely filled with the grease and did not enter the contact electrode side. Further, although the groove 12 of this embodiment is provided in a cubic shape, the shape of the groove is not particularly limited to a cubic shape, and according to the experiments of the present inventors, the contact electrode side of the groove is sharply raised. Although a better result was obtained, a sufficient effect could be obtained if the groove 12 had a certain volume.

<Embodiment 2> In this embodiment, the above-mentioned embodiment 1 is used.
In a fixing device substantially similar to the above, the heater shape is thicker on the film contact surface side at the end as shown in FIG. At this time, the wall 12 at the boundary between the thickened portion and the other portion
The angle θ shown in FIG. 3 is 90 ° or less. By setting this angle θ to 90 ° or less, the lubricant 9
Can more effectively be prevented from entering the contact electrode side. The edge of the film 2 with respect to this heater 3 is in any case on the heating area side with respect to the boundary wall 12 so that it does not get over this wall. Further, the roller portion 8 of the pressure roller 6 is always positioned inside the wall 12. In the present embodiment, the angle θ of the wall 12 is set to 80 ° and the height is set to 2.5 mm, but according to the experiments by the inventors, this angle and shape are sufficient, but the size and the life are increased. For the purpose of illustration, it has been found that it is better to form the wall 12 into a shape having a fold as shown in FIG. Another advantage of this embodiment is that the contact electrode 10 at the end of the heater 3 is thickened to increase the strength, and when the contact is pressed by spring pressure of metal or the like, the pressure can be increased. it can. This is because the increase in the heat capacity of the heater is small compared to making the entire heater thicker,
The power saving, the shortening of the wait time, etc., which are one of the great advantages of the present invention, are hardly impeded.

When the heater 3 of this embodiment is used, the film 2
There is also an advantage that the axial deviation control of the above can be performed by abutting on the wall 12.

<Embodiment 3> In this embodiment, in the fixing device substantially the same as the above-mentioned embodiment 1, the heater 3 itself uses a flat plate shape similar to the conventional one, and its end portion is as shown in FIG. A U-shaped member 13 made of heat-resistant resin is provided so that the tip of the U-shaped member enters the stay 1. The member 13 has sufficient adhesion to the heater 3 on the contact surface with the heater 3 so that the lubricant 9 does not slip between the member 13 and the heater 3. If the heat-resistant resin alone does not provide sufficient adhesion, an elastic body (for example, heat-resistant rubber) may be attached to the contact surface with the heater, or a heat-resistant adhesive may be used to bond the heater. By attaching this member 13, the same effect as that of the above-described embodiment can be obtained, and when this embodiment is used, the structure and manufacturing of the heater 3 can be facilitated and the stay 1 and the heater 3 can be used together as a fixing member. There is an advantage that the adhesive force between the heater 1 and the heater 3 can be increased or other fixing method can be omitted.

<Embodiment 4> In this embodiment, in the fixing device substantially the same as the above-mentioned embodiment 1, the heater 3 itself uses a flat plate shape similar to the conventional one, and its end portion is as shown in FIG. Heat resistant absorber 14 (eg Nomex felt)
Is provided. The absorber 14 is provided between the heating region coated with the lubricant 9 and the contact electrode 10, and absorbs the lubricant 9 entering the contact electrode 10 from the heating region. The lubricant 9 once absorbed by the absorber continues to be retained in the absorber 14 by the capillary phenomenon. Further, in order to enhance the effect of this embodiment, a sheet that does not pass the lubricant 9 may be attached to the contact electrode side of the absorber 14. By using this embodiment, it is possible to obtain the same effect as that of the above embodiment, and when using this embodiment, there is an advantage that the heater need not be complicatedly machined and can be easily attached.

<Embodiment 5> In this embodiment, in a fixing device substantially similar to that in Embodiment 1, the fixing film 2a is changed from a conventional simple cylindrical shape to an opening at the end as shown in FIG. It has a shape that narrows inward. In the case of the conventional simple cylindrical film, if the recording material P is subjected to the fixing process many times, the lubricant 9 applied to the back side at the end portion of the film 2a wraps around to the front side (fixing surface). The lubricant 9 that has flowed around the recording material P from the surface of the film 2a.
The recording material is transferred to the surface to stain the recording material, or the releasability of the surface of the film 2a is deteriorated.
A so-called offset phenomenon occurs in which the toner adheres to the surface of a. However, when the lubricant 9 is formed as in this embodiment, it is possible to prevent the lubricant 9 from flowing around from the end portion. According to the experiments conducted by the present inventors, when 50 mg of fluorine-based grease is applied to the heater 3, when the conventional simple cylindrical film is used, the recording material P of the recording material P is fixed when about 5000 sheets are fixed. Contamination was generated on the edges, whereas when the film of this example was used, the recording material was not stained even after the fixing process of about 100,000 sheets. Again 10
In the case of the present embodiment, the reduction amount of the lubricant 9 after the fixing process of ten thousand sheets is also about 1/4 of that in the case of using the simple cylindrical film, which is also an advantage.

Further, as an advantage of this embodiment, in the conventional tension-free film type heating device, the end portion of the film having a relatively large thickness and rigidity is brought into contact with the member for stable running of the film. However, when the present embodiment is used, the thin portion can be controlled by the tension by the internal stay 1, so that the film can be made thinner and the temperature of the heater 3 can be lowered as compared with the contact method. You can <Embodiment 6> In this embodiment, the end portion of the film 2b is widened into a trumpet shape as shown in FIG.

The shape of the film is as shown in FIG. 8 and the longitudinal dimension thereof is longer than that of the roller portion 8 of the pressure roller 6 as shown in FIG. Since the lubricant 9 does not come into contact with the lubricant 9, the lubricant 9 is less likely to wrap around. In addition, the wraparound of the lubricant 9 tends to cause the lubricant 9 adhering to the end portion of the film to be thinly and widely spread between the end portion of the film and the pressure roller 6 like a capillary phenomenon. If it is not in contact with the pressure roller 6, the lubricant 9 attached to the end of the film is
It does not extend to a portion (heated material heating region) in contact with the recording material P on the front side of the film. As a result, the same effect as in the above embodiment can be obtained.

The use of this embodiment is advantageous in that the film can be manufactured relatively easily and the assembling property of the apparatus can be improved.

<Embodiment 7> In this embodiment, a rib 16 having a shape as shown in FIG. 10 is adhered to the outer periphery of the end portion of the film 2c in a fixing device which is substantially the same as the embodiment 5.
The rib 16 is attached so as to be located outside the roller portion 8 of the pressure roller 6. Due to the ribs 16, the lubricant 9 coming out from the inner periphery of the film 2c
When it adheres to the outer peripheral surface of c, the lubricant 9 is prevented from reaching the heating region of the material to be heated of the film 2c, and the same effect as in the above embodiment can be obtained. At this time,
The rib 16 has sufficient height and strength, and when the film tries to approach one side for some reason, the pressure roller 6
Even if it hits the roller portion 8, the rib 16 is prevented from being peeled off or over the roller portion 8, so that the film deviation can be controlled. According to the experiments conducted by the inventors of the present invention, the lubricant did not adhere to the heated region of the material to be heated of the film even after the paper feed test of 150,000 sheets. Further, in this embodiment, since the strength of the film can be obtained even if the film is thinned, the temperature of the heater 3 can be lowered, and there are advantages such as reduction of power consumption and improvement of durability of each component. is there.

[0040]

As described above, the present invention relates to a film heating type heating apparatus. In the first invention, the film is formed by changing the shape between the heating region at the end of the heater and the contact electrode. The effect that the lubricant applied to the inner surface can be prevented from entering the contact electrode, contact failure due to the lubricant can be prevented, and stable and favorable heat treatment can be always performed is obtained.

Further, in the second invention, the lubricant is prevented from wrapping around the film surface (front side) by changing the shape of the film end portion, and the recording material is contaminated by the lubricant or the film is formed by the lubricant. It is possible to eliminate the offset of the toner to the toner and to obtain a stable and good fixed image.

[Brief description of drawings]

FIG. 1 is a sectional view of a heater according to a first exemplary embodiment.

FIG. 2 is a schematic sectional view of a fixing device applicable to Embodiments 1 to 7.

FIG. 3 is a sectional view of a heater according to a second exemplary embodiment.

FIG. 4 is a partially enlarged cross-sectional view showing a modified example of the heater of the second embodiment.

FIG. 5 is a perspective view of a heater according to a third exemplary embodiment.

FIG. 6 is a perspective view of a heater according to a fourth exemplary embodiment.

FIG. 7 is a perspective view of a film of Example 5.

FIG. 8 is a perspective view of a film of Example 6.

FIG. 9 is a cross-sectional view of a fixing device according to a sixth exemplary embodiment.

FIG. 10 is a perspective view of a film of Example 7.

[Explanation of symbols]

 2 Film 3 Heater (Heating Body) 6 Pressure Roller (Pressure Member) 9 Lubricant 10 Contact Electrode 12 Groove 13 Inflow Prevention Member 14 Absorber

Claims (7)

[Claims] 1. A pressure member is brought into pressure contact with a fixedly supported heating body through a film, and a material to be heated is introduced between the film and the pressure member as the film moves and moves.
In the heating device, heat energy is applied to the material to be heated from the heating body through the film, and a lubricant is interposed between the heating body and a surface of the film in contact with the heating body. A heating device characterized in that a dam-like or groove-like portion or member is provided near the electrical contact portion of the body. 2. The position of the dam-like or groove-like portion or the position of the member near the electric contact portion of the heating body is inside the electric contact position in the axial direction of the heating body, and the film of the pressing member or the heating body contact. It is outside the member.
The heating device according to. 3. The heating device according to claim 1, wherein the thickness of the heating body in the electric contact portion of the heating body is thicker on the heating surface side than on the heating region. 4. The shape of the dam-like or groove-like portion or member near the electric contact portion of the heating element on the heating area side is 90 ° or less with respect to the heating area surface of the heating element. The heating device according to 1. 5. The heating device according to claim 1, wherein the dam-like or groove-like member provided in the vicinity of the electric contact portion of the heating body has a good absorbability for the lubricant. 6. A film is brought into contact with and slid on a fixedly supported heating body, and a material to be heated is brought into close contact with the surface of the film opposite to the heating body to move and pass through the film together with the film. A heating device in which heat energy is applied to a material to be heated from the heating body through the film, and a lubricant is interposed between the heating body and a surface of the film in contact with the heating body. A heating device characterized in that a portion having a shape for preventing the lubricant from moving to the contact surface of the material to be heated of the film is provided at the end portion of the. 7. The film according to claim 6, wherein the end portion of the film is provided with both the inner peripheral surface and the outer peripheral surface of the film, or a portion where one of these surfaces does not come into contact with another member. Heating device.