JPH06314041A - Heating device, image forming device and heater - Google Patents

Abstract

PURPOSE:To reduce the deterioration and wear of a film caused by making the temperature of a heater higher at a press-contact nip part when a process speed is increased by preheating a material to be heated in an area in front of the heater before the material to be heated is heated at the press-contact nip part. CONSTITUTION:A recording material P with an unfixed toner image T carried passes through an area L in front of the heater while coming close to, or in soft contact with the surface of the heater 20 facing the front area L through a film 25 before rushing into the press-contact nip part N. The area L is sufficiently warmed up by a 2nd resistance heat generater 23b, so that the recording material P and the unfixed toner image T are preheated while they are passing through the area L before the recording material P enters the nip part N. Thus, even in the case of increasing the process speed, excellent heat-treatment ability can be secured even in the case of setting the temperature of the heater lower at the nip part N, and also, good fixation can be secured with reference to the recording material P.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure contact nip formed by a heating member and a pressing member sandwiching the heat-resistant film with a heat-resistant film being brought into close contact with the heating member by a pressing member for sliding conveyance. The material to be heated is introduced between the heat-resistant film and the pressure member of the heating section, and the pressure-contact nip portion is nipped and conveyed together with the heat-resistant film to transfer the heat of the heating element to the material to be heated through the heat-resistant film. The present invention relates to a film heating type heating device. Further, the present invention relates to an image forming apparatus and a heating body.

[0002]

2. Description of the Related Art A film heating type heating device as described above is disclosed, for example, in JP-A-63-313182, JP-A-2-157878, JP-A-4-44075, and JP-A-4-204980. Have been proposed to
In image forming devices such as copiers, laser beam printers, facsimiles, microfilm reader printers, image display (display) devices, recorders, etc., heating and melting by appropriate image forming process means such as electrophotography, electrostatic recording, magnetic recording, etc. Purpose of forming by direct method or indirect (transfer) method on the surface of recording material (electrofax sheet, electrostatic recording sheet, transfer material sheet, printing paper, etc.) as an image support using a toner made of a resin having good properties It can be utilized as an image heating stationary apparatus that heats and fixes an unfixed toner image (fixed image) corresponding to the image information as a permanently fixed image on the surface of a recording material carrying the image.

Further, it is not limited to the fixing device, and can be widely used as a means and a device for heat-treating a material to be heated such as a device for heating a recording material carrying an image to modify its surface property, a hypothetical fixing device, and the like. .

The film heating type heating device is compared with other known heating roller type, hot plate type, belt heating type, flash heating type, open heating type heating devices or image heating fixing devices. ． Since a low-heat-capacity heater can be used as the heater and a thin-film heater with a low heat-capacity can be used, it is possible to save power and shorten the wait time (quick start), and suppress the temperature rise inside the unit. Can be done. The image heating and fixing device is advantageous in that it can prevent offset because the fixing point and the separation point can be set separately, and that it can solve various drawbacks of other types of devices.

FIG. 13 shows an enlarged cross-sectional model view of a main part of a film heating type heating device (image heating and fixing device).

Reference numeral 20 denotes a heating body (ceramic heater), and the heating body 20 has a heat resistant film (fixing film).
25 is brought into close contact with a pressure roller 28 as a pressure member to be slid and conveyed, and the heat resistant film 25 is sandwiched between the heating element 20 and the heating element 20.
A recording material P to be image-fixed as a material to be heated is introduced between the heat-resistant film 25 and the pressure roller 28 in the pressure contact nip portion (fixing nip portion) N formed by the pressure roller 28 and the pressure roller 28 and heat-resistant. The heat of the heating element 20 is applied to the recording material P via the heat-resistant film by nip-conveying the pressure contact nip portion N together with the heat-resistant film 25 to form an unfixed visible image (toner image) T on the recording material P. The image is fixed on the surface of the recording material P by heating. The recording material P passing through the pressure contact nip portion N is the film 25.
Is separated from the surface and is transported.

The heating element 20 is a heat-resistant film 25 or an elongated heat-resistant / insulating / heat-conductive substrate 22 having a longitudinal direction perpendicular to the conveying direction a of the recording material P as a material to be heated. A resistance heating element 23 formed along the length of the substrate at the center of the front side of the substrate in the lateral direction, a heat resistant overcoat layer 24 for protecting the surface of the heating element on which the resistance heating element is formed, and a resistance heating element. This is a linear heating element having a low heat capacity as a whole, which includes a power feeding electrode (not shown) at both longitudinal ends of 23 and a temperature detecting element 29 such as a thermistor for detecting the temperature of the heating element provided on the back surface side of the substrate.

This heating element 20 is fixedly arranged by exposing it downward on the surface side on which the resistance heating element 23 is formed and holding it to a heater support 21 having rigidity and heat insulation.

The heating element 20 is heated by heating the resistance heating element 23 over the entire length of the resistance heating element 23 by supplying power to the electrodes at both ends thereof, and the temperature rise is detected by the temperature detecting element 29. The current is fed back to a temperature control circuit (not shown) to control the energization of the resistance heating element 23 so that the temperature of the heating element is maintained at a predetermined temperature.

The heat-resistant film 25 may have an endless belt shape and may be rotationally driven to be conveyed, or a heat-resistant film 25 may be a roll-wound long film and fed and conveyed.

In the conventional apparatus, the widthwise center of the heating element substrate 22 and the widthwise center of the resistance heating element 23 are substantially aligned with the center of the pressure contact nip portion N.

The width W of the resistance heating element 23 in the widthwise direction is substantially equal to or less than the width of the pressure contact nip portion N, and the pressure contact nip portion N is heated intensively. It was

[0013]

However, in the case of the constitution in which the pressure contact nip portion N is mainly concentratedly heated as described above, the image heating and fixing device compares the recording material conveying speeds (process speeds) during fixing processing. When the process speed is high, the following problems occurred.

A. Resistance heating element 2 in the pressure contact nip portion N
Sufficient fixability cannot be obtained unless the temperature of 3 is raised. However, if the temperature of the heating element in the pressure contact nip portion N is increased, the heat-resistant film in the pressure contact nip portion N is worn more and the life of the film 25 is shortened. It adheres to the surface and adversely affects the fixed image.

B. When the recording material P carrying the unfixed toner image T plunges into the pressure contact nip portion N and is rapidly heated by the high temperature of the pressure contact nip portion, the moisture contained in the recording material P explodes at a time. A large amount of water vapor is generated and blows out from the pressure contact nip portion N toward the recording material carry-in port of the nip portion as indicated by an arrow b, which causes a problem that the unfixed toner image T is scattered.

This phenomenon is particularly caused when the steam b generated in the pressure contact nip portion N is blown out in the line image perpendicular to the recording material conveying direction a, because the line image blocks the escape path of the steam. Likely to happen.

Therefore, the present invention aims to solve the above problems a and b.

[0018]

The present invention is a heating device, an image forming apparatus, and a heating body characterized by the following constitutions.

(1) A heat-resistant film is brought into close contact with a heating member by a pressure member to be slid and conveyed, and a heat-resistant film in a pressure contact nip portion formed between the heating member and the pressure member with the heat-resistant film sandwiched therebetween. In a heating device for introducing heat to be heated between the heating member and the pressure member and for conveying the heat of the heating body to the member to be heated through the heat resistant film by nipping and transporting the pressure contact nip portion together with the heat resistant film. , The heating body has at least two peaks of heat generation distribution in the direction in which the material to be heated is conveyed,
At least one peak of the heat generation distribution is in the pressure contact nip portion, and at least another peak of the heat generation distribution is disposed upstream of the pressure contact nip portion in the material-to-be-heated conveyance direction. apparatus.

(2) A heat-resistant film is adhered to a heating member by a pressure member and slidably conveyed, and a heat-resistant film in a pressure contact nip portion formed by the heating member and the pressure member sandwiching the heat-resistant film. In a heating device for introducing heat to be heated between the heating member and the pressure member and for conveying the heat of the heating body to the member to be heated through the heat resistant film by nipping and transporting the pressure contact nip portion together with the heat resistant film. The heating element includes at least two resistance heating elements extending on the insulating heat conductive substrate at right angles to the direction in which the material to be heated is conveyed, and at least one resistance heating element is provided in the pressure contact nip portion, and at least another resistance heating element is provided. One resistance heating element is arranged upstream of the pressure contact nip portion in the direction in which the material to be heated is conveyed, and the resistance of the former resistance heating element is R ₁
And R ₂ is the resistance of the latter resistance heating element, R ₁
A heating device having a relationship of ≤ R ₂ .

(3) The temperature detecting element for detecting the temperature of the heating element is arranged on the back side of the heating element in the pressure contact nip region of the heating element (1) or (2). The heating device according to.

(4) Any one of (1) to (3), wherein the material to be heated is a recording material on which an image is to be fixed, and the image heating and fixing device heats and fixes an unfixed image on the recording material. The heating device according to claim 1.

(5) A heat-resistant film is adhered to a heating member by a pressure member and slidably conveyed, and a heat-resistant film in a pressure contact nip portion formed between the heating member and the pressure member with the heat-resistant film sandwiched therebetween. In a heating device for introducing heat to be heated between the heating member and the pressure member and for conveying the heat of the heating body to the member to be heated through the heat resistant film by nipping and transporting the pressure contact nip portion together with the heat resistant film. The heating element includes a resistance heating element extending in a direction perpendicular to the heating material conveyance direction, and at least a part of the resistance heating element is disposed outside the pressure contact nip portion on the heating material loading side. Characteristic heating device.

(6) A heat-resistant film is adhered to a heating member by a pressure member and slidably conveyed, and a heat-resistant film in a pressure contact nip formed between the heating member and the pressure member with the heat-resistant film sandwiched therebetween. In a heating device for introducing heat to be heated between the heating member and the pressure member and for conveying the heat of the heating body to the member to be heated through the heat resistant film by nipping and transporting the pressure contact nip portion together with the heat resistant film. The heating element includes a heat conductive substrate and a heating element formed on the substrate, and the center of the substrate in the lateral width direction is arranged on the heating material carry-in side with respect to the center of the pressure contact nip portion. A heating device characterized in that

(7) The heated material is a recording material on which an image is to be fixed, and an image heating and fixing device for heating and fixing an unfixed image on the recording material is described in (5) or (6). Heating device.

(8) An image forming apparatus comprising the heating device according to any one of (1) to (7) as an image heating fixing device for heating and fixing an unfixed image on a recording material. .

(9) A substrate and a resistance heating element formed on the substrate are basic constituents, and are heating elements for supplying electric power to the resistance heating element to generate heat, and with respect to the relative movement direction with respect to the object to be heated. And at least two exothermic distribution peaks.

(10) A substrate and a resistance heating element formed on the substrate are the basic constituents, and are heating elements for supplying electric power to the resistance heating element to generate heat, and with respect to the relative movement direction with respect to the object to be heated. And at least two resistance heating elements that extend at right angles,
When the resistance of at least one resistance heating element is R ₁ and the resistance of at least one other resistance heating element is R ₂ , R
A heating element having a relationship of ₁ ≤ R ₂ .

(11) A substrate and a resistance heating element formed on the substrate are basic constituent elements, and are heating elements for supplying electric power to the resistance heating element to generate heat, and with respect to the relative movement direction with respect to the object to be heated. And a resistance heating element extending at a right angle, and at least a part of the resistance heating element is disposed outside a pressure contact nip portion with a pressure member that presses a material to be heated against the heating element.

(12) A substrate and a resistance heating element formed on the substrate are basic constituent elements, and are heating elements for supplying electric power to the resistance heating element to generate heat, and with respect to the relative movement direction with respect to the object to be heated. And a resistance heating element extending at a right angle is provided, and the center of the relative movement direction of the substrate with respect to the object to be heated is arranged at a position different from the center of the pressure contact nip portion with the pressing member for pressing the material to be heated against the heating member. A heating element characterized by being.

[0031]

[Action]

1) The heating body surface area (heating body front surface area) on the upstream side of the pressure contact nip portion in the conveying direction of the material to be heated (heater front surface area) has a peak of heat generation distribution, or a resistance heating element exists, or the resistance heating body of the pressure contact nip portion is extended. Since the presence of a portion or good heat transfer from the pressure contact nip portion allows sufficient heating, the material to be heated passes through the front surface region of the heater before entering the pressure contact nip portion, and the material to be heated passes through the film. Pre-heating (pre-heating) is performed by passing the surface of the front surface region in close proximity or while being in slight contact therewith. The preheated material to be heated is subsequently heated in the process of passing through the pressure contact nip portion, and if the material to be heated is a recording material, the toner image is fused and fixed by heating.

Therefore, the material to be heated is preheated in the front surface region of the heating body before being heated in the pressure welding nip portion, so that the heating body temperature in the pressure welding nip portion is set low even when the process speed is increased. However, it is possible to secure good heat treatment properties and good fixing properties for recording materials. A film that accompanies increasing the heating body temperature in the pressure contact nip when the process speed is increased. It is possible to eliminate or reduce the problems of deterioration and wear.

2) By preheating the material to be heated in the front surface area of the heating body before the material to be heated plunges into the pressure contact nip portion, it is possible to evaporate a part of the water content in the material to be heated. In that case, unfixed toner is "sticky" by previous heating
Since the recording material is held in pressure contact with the film, the recording material enters the recording material carry-in side from the pressure contact nip portion of the recording material-containing water vapor due to rapid heating when the recording material plunges without preheating. It is possible to reduce a large number of explosive blowouts of a single time and the scattering phenomenon of the horizontal line toner image due to the blowouts.

3) By providing a resistance heating element in the front area of the heating element, the temperature of the area can be positively and quickly brought to a predetermined temperature, and the wait time can be further shortened.

[0035]

【Example】

<First Embodiment> (FIGS. 1 to 4) FIG. 1 is a schematic configuration diagram of an example of a film heating type image heating and fixing device as a heating device of this embodiment, and FIG. 2 is an enlarged cross-sectional model of a main part. FIG. 3 and FIG. 3 are plane model views of the heating element with the middle part omitted and partially cut away. The same components and parts as those of the apparatus shown in FIG. 13 are designated by the same reference numerals, and the repeated description will be omitted.

In FIG. 1, the heat-resistant film 25 is an endless belt-shaped film, and is fixedly supported by a driving roller 26, a driven roller 27, and a heater support 21 below the rollers 26 and 27. And the three members 26, 27, 20 parallel to each other
It is suspended between them.

The driven roller 27 also serves as a tension roller for the film 25, and the film 25 is conveyed in a clockwise direction at a predetermined peripheral speed as the drive roller 26 is driven to rotate in the clockwise direction, that is, from the image forming portion side (not shown). The unfixed toner image T is rotatively driven without wrinkles, meandering, or speed delay at the same peripheral speed as the conveying speed of the recording material P as a material to be heated having the unfixed toner image T carried on the upper surface.

The pressure roller 28 is a roller having a rubber elastic layer having a good releasability such as silicon rubber, and is sandwiched by the film portion on the descending side of the film 25 and is urged against the lower surface of the heating body 20 by an urging means. For example, the contact pressure is applied with a contact pressure of 4 to 10 kg in total, and the recording material P rotates in the forward counterclockwise direction in the conveying direction.

Since the endless belt-shaped film 25 that is rotationally driven is repeatedly subjected to heat fixing of a toner image, it has excellent heat resistance, releasability, durability, etc., and generally has a total thickness of 100 μm or less, preferably Is a thin wall of 40 μm or less.

For example, polyimide, polyetherimide,
A single layer film of a heat-resistant resin such as PES / PFA (tetrafluoroethylene-fluoroalkylvinyl ether copolymer resin) or a composite layer film, for example, a 20 μm thick film, is provided with PTFE (tetrafluoroethylene) on at least the image contact surface side. (Resin) -PAF or the like, and a release coating layer having a thickness of 10 μm in which a conductive material is added to a fluororesin.

The heater support 21 is made of, for example, high heat resistant resin such as PPS (polyphenylene sulfide), PAI (polyamide imide), PI (polyimide), PEEK (polyether ether ketone), liquid crystal polymer, or these resins and ceramics metal. -Can be composed of composite materials such as glass.

The substrate 22 of the heating element 20 is, for example, a good heat conductor having a thickness of 1 mm, a width of 10 mm, and a length of 240 mm, such as alumina or aluminum nitride.

In the present embodiment, the heating element 20 is provided with two first and second low-heat-capacity energizing heating elements 23a and 23b on the surface of the substrate 22 thereof. The two electric heating elements 23a and 23b are formed in parallel on the surface of the substrate 22 at intervals along the longitudinal direction as shown in FIG. 3, and each of them is made of Ag / Pd, RuO ₂ , Ta ₂ N, etc. The electric resistance material is applied in a linear or strip shape by screen printing or the like.

The width of the first electric heating element 23a is 2.5 mm.
The width of the second electric heating element 23b is 1 mm. Reference numerals 31a, 31a, 31b and 31b are power supply electrodes that are formed on both end surfaces of the substrate surface by conducting to both end portions of the first and second electric heating elements 23a and 23b. It is formed by coating by screen printing or the like. Between the electrodes 31a and 31a and between the electrodes 31b and 31b
The first and second energization heating elements 23a and 23b each generate heat over their entire length by being energized by an energization circuit (not shown).

The heat resistant overcoat layer 24 for protecting the surface of the heating element 20 is, for example, a heat resistant glass layer.

Reference numerals 29a and 29b denote first and second temperature detecting elements (thermistors and the like), which are arranged in contact with the positions on the back side of the substrate corresponding to the positions of the first and second resistance heating elements 23a and 23b, respectively. It is set up.

Then, the film 2 is attached to the heating body 20.
5 in a state where the pressure roller 28 is pressed against the heating roller 20 and the pressure roller 28 is pressed against the heating roller 20 with the film 25 interposed therebetween, the width region of the pressing nip portion N (about 3 mm in this embodiment). The first resistance heating element 23a is positioned within the width), and the second resistance heating element 23b is positioned upstream of the pressure contact nip portion N in the film transport direction.
That is, L is a width region (heating body front face region) of the heating body surface portion on the upstream side in the film transport direction with respect to the pressure contact nip portion N, and the second resistance heating element 23b is located in the heating body front face region L. There is.

The first and second resistance heating elements 23a and 23b are respectively set to a predetermined temperature, for example, the first temperature, according to the outputs of the first and second temperature measuring elements 29a and 29b provided on the back surface of the substrate. The temperature of the resistance heating element 23a is adjusted to 190 ° C, and the temperature of the second resistance heating element 23b is adjusted to 180 ° C.
The heat distribution at that time is as shown in FIG.

With the above-described structure, the recording material P carrying the unfixed toner image T on the front surface region L of the heating body 20 through the film 25 of the heating body 20 before entering the pressure contact nip portion N. The object passes through the surface of the front surface region L while approaching or lightly contacting it. The front area L of the heating element is the second resistance heating element 2
Since the recording material P is sufficiently warmed by 3b, the recording material and the unfixed toner image are preheated while the recording material P passes through the front area L of the heating body before entering the pressure contact nip portion.

The preheated recording material P is subsequently heated by the heat generated by the first resistance heating element 23a in the process of passing through the pressure contact nip portion N, and the toner image T is heated and fused and fixed.

Therefore, the recording material P and the unfixed toner image T
Is pre-heated in the front region L of the heating body, so that even when the process speed is increased, it is possible to secure good fixing property even if the heating body temperature in the pressure contact nip portion N is set low. It is possible to eliminate or reduce the problem of deterioration and wear of the film 25 which is caused by raising the temperature of the heating body in the pressure contact nip portion N when the process speed is increased.

Preheating of the recording material in the front surface region L of the heating body before the recording material P rushes into the pressure contact nip portion N makes it possible to evaporate a part of the moisture in the recording material, and the unfixed toner T Since the preheating causes "stickiness", the recording material P is rapidly heated when the recording material P plunges into the pressure contact nip portion N where the recording material P and the film 25 come into pressure contact with each other without preheating. It is possible to reduce a large amount of explosive blowout of the contained water vapor from the pressure contact nip portion N to the recording material carry-in side, and the scattering phenomenon of the horizontal line toner image due to the blowout.

The second resistance heating element 23 is provided in the front area L of the heating element.
By providing b, the temperature of the region L can be positively and quickly brought to a predetermined temperature, and the wait time can be further shortened. <Second Embodiment> (FIG. 5) In the first embodiment, the first and second resistance heating elements 23a and 23b of the heating element 20 are independently associated with each other.
Although the temperature control is performed on each of them according to the temperature detected by the second temperature detecting elements 29a and 29b, only the first resistance heating element 23a corresponding to the pressure contact nip portion N is temperature controlled and the front surface region L of the heating element L is controlled.
A constant power may be applied to the second resistance heating element 23b corresponding to.

For example, in the first embodiment, the second
As shown in FIG. 5, the temperature detecting element 29b of No. 1 is removed, and constant power is applied to the second resistance heating element 23b to generate the first resistance heating element 2b.
3a was adjusted in temperature to 190 ° C. based on the temperature detected by the temperature detecting element 29 corresponding thereto, and the image fixing process of the recording material P was executed. As a result, sufficient fixing property was obtained as in the first embodiment.
In addition, a good fixed image without toner scattering was obtained.

The front surface region L of the heating element outside the pressure contact nip portion N
The electric power applied to the second resistance heating element 23b corresponding to the first resistance heating element 23 in the press contact nip portion N is
It is smaller than the maximum power applied to a. This is because in the heat generating portion in the pressure contact nip portion N, most of the generated heat amount is deprived by the film 25, the recording material P, the pressure roller 28, etc., and the temperature decreases, so more power is consumed. .

As a method of reducing the electric power applied to the second resistance heating element 23b, there are methods such as lowering the applied voltage and increasing the resistance value of the resistance heating element 23b, but any method may be used.

<Third Embodiment> (FIG. 6) In the first and second embodiments, the first and second heaters 20 are provided.
Although the resistance heating elements 23a and 23b are independently supplied with electric power to generate heat, both resistance heating elements 23a and 23b may be energized from the same electrode to perform the same temperature control.

This embodiment is an example of this, and as shown in FIG. 6, the first and second resistance heating elements 23a and 23b are energized from the common electrodes 31 and 31 at both ends thereof to generate heat.

The temperature of the heating element 20 is controlled by the first resistance heating element 23.
The temperature in the area of the pressure contact nip portion N is set to a predetermined temperature according to the output of the temperature detecting element 29 corresponding to a.

In such a configuration, the first and second
Since the same voltage is applied between the resistance heating elements 23a and 23b, the current flowing through the resistance heating elements (that is, the power applied to the heating elements) is the resistance value ratio of the resistance heating elements 23a and 23b. Divided by. Here, the resistance value of the first resistance heating element 23a is R ₁ , and the resistance value of the second resistance heating element 23b is R ₂ .

In the heating device of this embodiment, the heating element 2
The heat of 0 is fixing film 25, recording material P, pressure roller 28.
・ Diffuse into the heater support 21 and the like. At this time the first
And the second resistance heating element 23a, 23b, the pressure contact nip portion N
The first resistance heating element 23a in the heating body surface area which is strongly pressed against the film 25 and the recording material P by means of
The amount of heat taken away is larger than that of the second resistance heating element 23b on the side. Therefore, when the same current is applied to the first and second resistance heating elements 23a and 23b, that is, when R ₁ = R ₂ ,
The temperature of the second resistance heating element 23b becomes higher.

When the relationship between the resistance values of both is set to R ₁ > R ₂ , I ₁ <I _{2 is obtained} from V = IR, which is _second to the heat generation amount of the first resistance heating element 23 a portion from W = VI. The amount of heat generated by the resistance heating element 23b is large, and the amount of heat taken by the first resistance heating element 23a is large as described above. The temperature of the resistance heating element 23b is significantly increased. This is not preferable because when the temperature of the pressure contact nip portion N is adjusted to a required temperature, for example, 190 ° C., the second resistance heating element 23b exceeds the heat resistant temperature of the heater support 21 and the film 25.

Therefore, it is preferable that R ₁ = R ₂ or R ₁ <R, where the temperature rise of the second resistance heating element 23 b is relatively small.

In this embodiment, as the heating element 20, a first resistance heating element 23a having a width of 2 mm is centered on a line 4 mm at the most downstream side in the film transport direction on an alumina substrate 22 having a thickness of 1 mm, a width of 10 mm and a length of 270 mm. , 2mm width 1mm centered on the line 7mm from the most downstream in the film transport direction
The resistance heating element 23b was provided, and a heat-resistant glass layer having a thickness of 30 μm was provided as the overcoat layer 24 on the surface.

First and second resistance heating elements 23a and 23b
Are made of the same material, and the resistance value is determined by the width. In this embodiment, 2R ₁ ≈R ₂ .

By incorporating this heating element 20 in the apparatus shown in FIG.
The temperature inside the pressure contact nip portion N was adjusted to 180 ° C. by the temperature detecting element 29 corresponding to the first resistance heating element 23a.

Copier FC-3 / manufactured by Canon Inc.
The recording material P carrying the unfixed image T formed with the toner for No. 5 was heated and fixed at a conveying speed of 100 mm / sec. As a result, a satisfactory fixed image with no toner scattering was obtained. I was able to get it.

Further, the first and second resistance heating elements 23a.
Since the same electrodes 31 and 31 are energized with respect to 23b, between the electrodes on the heating body 20 (electrode 31 in FIG. 3).
It is not necessary to take a creepage distance (between a and 31b), and the heating body 20 itself can be miniaturized.

Further, there is a merit that the structure of the energizing electrode side, which energizes the heating element electrodes 31 from the power source, is simple and can be downsized.

(Comparative Example) As a comparative example, a heating body having the same structure as that of the third embodiment except that the second resistance heating body 23b was not provided with a coating tool was prepared. When the recording material on which the unfixed image is formed and carried by the toner for Canon Co., Ltd. copying machine FC-3 / 5 is conveyed at 100 mm / sec, the fixing property is sufficient. In order to obtain, it was necessary to control the temperature of the heating body by 200 ° C.

When a recording material left in a high humidity environment (humidity 90%) for a long period of time was used, the first several sheets to several tens of sheets were considered to be caused by water vapor in the recording material. Toner scattering was observed on the fine lines of the toner image in the right angle direction.

<Fourth Embodiment> (FIG. 7) The substrate 22 of the heating element 20 does not have to be a flat plate and may have another shape. This embodiment shows an example thereof.

The heating element 20 of FIG. 7 has an arcuate surface toward the upstream side of the film 25 in the transport direction, and the second resistance heating element 23b is disposed on this arcuate surface. The pressure contact nip portion N that is formed with the pressure roller 28 sandwiching it is flat and has a first resistance heating element 23a.

By making the upstream side of the heating member 20 in the film conveying direction an arc-shaped surface as in this embodiment, the adhesion with the film 25 becomes better than that of a flat plate, so that the film 25 is heated efficiently. Since the temperature of the film surface rises, it is effective in improving the fixing property and preventing toner scattering.

In the present embodiment, the upstream side of the heating element 20 in the film transport direction has an arcuate surface, but the whole may have an arcuate surface.

<Fifth Embodiment> (FIG. 5) In the heating body 20 of this embodiment shown in FIG.
Is a good heat conductor having a thickness of 1 mm, a width of 10 mm, and a length of 240 mm, such as alumina or aluminum nitride. There is only one resistance heating element 23, and its width is 2.5 mm.
n ₁ is the width center of the press contact nip portion N (heat generation center), n ₂ is the width center of the substrate 22 (widthwise center), and n ₃ is the resistance heating element 2.
3 is the width center (center in the width direction).

In the resistance heating element 23, the width center n ₁ is the substrate 2
It is formed and provided on the surface of the substrate 22 so as to be located on the recording material discharge side by about 1.5 mm from the width center n _{2 of 2} . Further, the pressure roller 28 is placed on the heating body 20 via the film 25 so that the width center of the pressure contact nip portion N and the width center n ₃ of the resistance heating element 23 are substantially aligned with each other and the width of the pressure contact nip portion N is about 3 mm. Are arranged under pressure.

In the above structure, the recording material P carrying the unfixed toner image T is formed on the front surface region L of the heating member which is formed wider than the pressure contact nip portion N upstream of the pressure contact nip portion N before entering the pressure contact nip portion N. Through the film 25 while approaching or lightly contacting the surface of the front surface region L of the heating element 20.

Since a good thermal conductor is used as the heating element substrate 22, the heat generated in the resistance heating element 23 is transferred during the fixing process, and the heating element portion in the front area L of the heating element is also at a high temperature. The recording material P and the unfixed toner image are preheated while the material P is passing through the front surface region L of the heating body before entering the pressure contact nip portion N.
Then, in the process of passing through the pressure contact nip portion N, main heating is performed by the heat generated by the resistance heating element 23, and the toner image T is heated and fused and fixed.

Therefore, also in the case of this embodiment, the first to fourth
In the same manner as in Example 1, a satisfactory fixed image and a good fixed image with no NATO scattering can be obtained.

It should be noted that widening the entire width of the heating body substrate 22 (both the recording material carry-in side and the carry-out side) in order to simply lengthen the heating body front surface area L increases the heat capacity of the entire heating body. Not only the electric power required to raise the temperature of the resistance heating element 23 (the temperature in the pressure contact nip portion N) to the fixing possible temperature is increased, but also the heat transfer from the resistance heating element causes the recording material carry-in side and the carry-out side. Since it is divided into two equal parts, a sufficient effect cannot be obtained. <Sixth Embodiment> (FIG. 9) The heating body 20 of this embodiment shown in FIG. 9 has a substrate 22 having a width of about 8 mm, which is narrower than that of the fifth embodiment, which is 10 mm.

The width center n ₂ of the substrate 22 is substantially aligned with the width center n ₁ of the pressure contact nip portion N, and the resistance heating element 23 is formed outside the pressure contact nip portion N to the front area L of the heating element.

When such a heating body 20 is used, the time (L / (process speed)) for preheating the recording material P and the unfixed toner T before entering the pressure contact nip portion N is the same as the fifth embodiment. Although shorter than in the case of the example, the resistance heating element 23 also generates heat in the heating body front surface region L, so that the temperature of the heating body portion in the heating body front surface region L becomes higher. The effect of is obtained.

Further, since the heat capacity of the entire heating body 20 can be reduced, it is possible to reduce the electric power and the wait time. In particular, if a heat-resistant resin substrate having poor thermal conductivity is used, the power consumption can be further reduced and the wait time can be shortened.

<Seventh Embodiment> (FIG. 10) In the heating element 20 of this embodiment shown in FIG. 10, the width center n ₂ of the good thermal conductive substrate 22 is set to be smaller than the width center n ₁ of the pressure contact nip portion N. By arranging on the recording material carry-in side, and also by arranging the resistance heating element center n _{3 on the} recording material carry-in side, the heating body front surface region L is also configured to generate heat.

With such a structure, the heating member front surface region L for preheating the recording material P before the recording material P enters the pressure contact nip portion N can be lengthened, and the heating member temperature in the region L can be increased. The higher the effect, the higher the effect.

<Example of Image Forming Apparatus> (FIG. 11) FIG. 11 shows an image in which the film heating type heating apparatus according to the present invention as shown in the first to seventh embodiments is incorporated as the image heating and fixing apparatus 11. The schematic structure of an example of a forming apparatus is shown. The image forming apparatus of this embodiment is a reciprocating platen type, a rotary drum type, a transfer type, and a process cartridge attaching / detaching type electrophotographic copying apparatus.

Reference numeral 100 denotes an apparatus casing, and 1 denotes a reciprocating type document placing table made of a transparent plate member such as a glass plate disposed on an upper surface plate 100a of the apparatus casing.
The upper part is driven to reciprocate to the right a and the left a'in the drawing at a predetermined speed.

Reference numeral G denotes an original document, which is placed on the upper surface of the original document table 1 with the image surface side to be copied facing downward according to a predetermined placement standard, and the original document pressure plate 1a is placed on the original document platen 1a and pressed down. Set.

Reference numeral 100b denotes a slit opening serving as a document illuminating section which is opened on the surface of the machine top plate 100a with a direction perpendicular to the reciprocating direction of the document placing table 1 (direction perpendicular to the paper surface) as a longitudinal direction.

The downward image surface of the document G placed and set on the document placing table 1 is sequentially moved from the right side to the left side in the slit opening portion 10 in the forward movement process of the document placing table 1 to the right a.
0b, the light L of the lamp 3 is received through the slit opening 100b and the transparent original placing table 1 for illumination scanning during the passage, and the reflected light on the original surface of the illumination scanning light is image element array. The image is exposed on the surface of the photosensitive drum 4 by 2.

The photosensitive drum 4 is coated with a photosensitive layer such as a zinc oxide photosensitive layer, an organic semiconductor photosensitive layer, and the like.
It is rotationally driven in the clockwise direction indicated by an arrow b at a predetermined peripheral speed around a, and in the course of the rotation, it is subjected to uniform charging treatment of positive polarity or negative polarity by the charger 5, and the uniformly charged surface is subjected to the above-mentioned By receiving the image formation exposure (slit exposure) of the document image, an electrostatic latent image corresponding to the image-formed exposure document image is sequentially formed on the surface of the photosensitive drum 4.

This electrostatic latent image is successively visualized by the developing device 6 with toner made of resin or the like which is softened and melted by heating,
The toner image, which is the visible image, moves to a portion where the transfer discharger 9 as a transfer portion is provided.

Reference numeral S denotes a cassette in which transfer material sheets P as recording materials are stacked and housed, the sheets in the cassette are fed out and fed one by one by the rotation of the feeding roller 7, and then the drum 4 by the registration roller 8. When the tip of the upper toner image forming portion reaches the portion of the transfer discharger 9, the tip of the transfer material sheet P also arrives at the position between the transfer discharger 9 and the photosensitive drum 4, and the timing is adjusted so that they coincide with each other. It is then delivered synchronously.

Then, the toner image on the side of the photosensitive drum 4 is sequentially transferred by the transfer discharger 9 to the surface of the fed sheet.

The sheet to which the toner image has been transferred at the transfer portion is sequentially separated from the surface of the photosensitive drum 4 by a separating means (not shown), and is guided to the fixing device 11 by the conveying device 10 to carry the unfixed toner. The image T is heated and fixed, and a guide 43 and a discharge roller 44 are formed as an image formed product (copy).
Then, the sheet is discharged onto the sheet discharge tray 12 outside the machine.

The surface of the photosensitive drum 4 after the image transfer is subjected to removal of adhering contaminants such as transfer residual toner by the cleaning device 13 and is repeatedly used for image formation.

The PC is a process cartridge which is attached / detached to / from the cartridge attaching / detaching portion 50 in the apparatus main body 100. In the case of this example, the photosensitive drum 4, the charging device 5, the developing device 6 and the cleaning device 13 as an image carrier are provided. The four process devices are included and can be collectively attached to and detached from the apparatus main body 100. <Another Configuration Example of Heating Device> (FIG. 12) FIGS. 12A, 12B, and 12C show other configuration examples of the film heating type heating device, respectively.

In the case of (a), an endless belt-shaped heat-resistant film 25 is suspended and stretched between two members of the heating body 20 and the driving roller 26, and the driving roller 26 rotationally drives.

In the case of (b), a cylindrical heat-resistant film 25 is loosely fitted on the outside of the heating body 20 and the film guide member 51 holding the heating body 20, and the heating body 20 is heated.
The film 25 is pressed against the film by a pressure roller 28, and the pressure roller 28 is rotated to drive the film 2
5 is a structure (pressurizing roller drive type) in which the inner surface of 5 is driven to rotate while closely sliding on the surface of the heating body 20.

In the case of (c), the heat-resistant film 25 is not an endless belt-shaped one, but a long end film wound in a roll is used.
It is configured to run at a predetermined speed from the side to the winding shaft 53 side via the heating body 20.

[0102]

As described above, the material to be heated is preheated in the front surface region of the heating body before being heated in the pressure contact nip portion, so that the heat in the pressure contact nip portion is heated even if the process speed is increased. Even if the body temperature is set low, it is possible to secure good heat treatment performance and good fixing performance for recording materials.When the process speed is increased, the heating body temperature of the pressure contact nip part becomes high. It is possible to solve or reduce the problems of deterioration and wear of the film due to the deterioration of the film.

It is possible to partially evaporate the water content in the heated material by preheating the heated material in the front surface area of the heating body before the heated material plunges into the pressure contact nip portion. Since the unfixed toner is given a “stickiness” by this preheating, the recording material accompanies a rapid heating when the recording material plunges into the pressure nip part where the recording material comes into pressure contact with the film without preheating. Explosive, large-scale blowout of material-containing water vapor from the pressure contact nip to the recording material loading side,
It is possible to reduce the scattering phenomenon of the horizontal line toner image due to the blowing.

By providing the resistance heating element in the front area of the heating element, the temperature of the area can be positively and quickly brought to a predetermined temperature, and the wait time can be further shortened.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a film heating type heating device (image heating and fixing device) according to a first embodiment.

[Fig. 2] Enlarged cross-sectional model view of main parts

[Fig. 3] Plan view of the heating element with the middle part omitted and partially cut away

[Fig. 4] Graph of the position of the heating element in the lateral direction and the amount of heat generated

FIG. 5 is an enlarged cross-sectional model view of a main part of the second embodiment device.

FIG. 6 is a plane model view of the heating body of the third embodiment device with the middle part omitted and partially cut away.

FIG. 7 is a plane model view of the heating body of the fourth embodiment device with the middle part omitted and partially cut away.

FIG. 8 is a structural model diagram of a main part of a fifth embodiment device.

FIG. 9 is a structural model diagram of a main part of a sixth embodiment device.

FIG. 10 is a schematic model diagram of a main part of a seventh embodiment device.

FIG. 11 is a schematic configuration diagram of an example of an image forming apparatus.

12 (a), (b), and (c) are schematic views of another example of the configuration of the film heating type heating device.

FIG. 13 is an enlarged cross-sectional model view of a main part of a heating body of a conventional device.

[Explanation of symbols]

 11 Fixing Device (Film Heating Type Heating Device) 20 Heater Support 22 Substrate 23.23a.23b Resistance Heating Element 24 Overcoat Layer 25 Heat Resistant Film 26 Drive Roller 27 Driven Roller 28 Pressure Roller 29.29a.29b Temperature Detector 31 ・ 31a ・ 31b Power supply electrode N Pressure contact nip part L Front area of heating element (pre-heating part)

Claims (12)

[Claims] 1. A heat-resistant film in a pressure-contact nip portion formed by a heating body and a pressing member, wherein a heat-resistant film is brought into close contact with a heating member by a pressing member and slidably conveyed, and the heating-resistant film is sandwiched between the heating member and the pressing member. In a heating device that introduces the material to be heated between the pressure member and conveys the heat of the heating body to the material to be heated via the heat resistant film by sandwiching and conveying the pressure contact nip portion together with the heat resistant film, The heating element has at least two heat generation distribution peaks in the direction in which the material to be heated is conveyed, and at least one heat generation distribution peak is at the pressure contact nip portion and at least one other heat generation distribution peak.
The heating device is characterized in that two peaks of heat generation distribution are arranged on the upstream side of the pressure contact nip portion in the material-to-be-heated conveyance direction. 2. A heat-resistant film in a pressure-contact nip portion formed by the heating body and the pressing member, wherein the heat-resistant film is brought into close contact with the heating member by a pressing member and slidably conveyed, and the heating-resistant film is sandwiched between the heating member and the pressing member. In a heating device that introduces the material to be heated between the pressure member and conveys the heat of the heating body to the material to be heated via the heat resistant film by sandwiching and conveying the pressure contact nip portion together with the heat resistant film, The heating element includes at least two resistance heating elements extending on the insulating heat conductive substrate at right angles to the direction in which the material to be heated is conveyed, and at least one resistance heating element is provided in the pressure contact nip portion and at least one other heating element. Two resistance heating elements are arranged upstream of the pressure contact nip portion in the material-to-be-heated conveyance direction,
A heating device having a relationship of R ₁ ≦ R ₂ where R ₁ is the resistance of the former resistance heating element and R ₂ is the resistance of the latter resistance heating element. 3. The temperature detecting element for detecting the temperature of the heating body is arranged on the rear surface side of the heating body in the pressure contact nip region of the heating body. Heating device. 4. The image heating fixing device according to claim 1, wherein the material to be heated is a recording material to be image-fixed, and the image-heating fixing device heat-fixes an unfixed image on the recording material. The heating device described. 5. A heat-resistant film in a pressure-contact nip portion formed between the heating body and the pressing member, wherein the heat-resistant film is brought into close contact with the heating member by a pressing member and slidably conveyed, and the heat-resistant film is sandwiched between the heating member and the pressing member. In a heating device that introduces the material to be heated between the pressure member and conveys the heat of the heating body to the material to be heated via the heat resistant film by sandwiching and conveying the pressure contact nip portion together with the heat resistant film, The heating element includes a resistance heating element extending in a direction perpendicular to the direction in which the material to be heated is conveyed, and at least a part of the resistance heating element is disposed outside the pressure contact nip portion on the heating material loading side. And heating device. 6. A heat-resistant film in a pressure-contact nip portion formed by a heating body and a pressing member, wherein the heat-resistant film is brought into close contact with a heating member by a pressing member and slidably conveyed, and the heating-resistant film is sandwiched between the heating member and the pressing member. In a heating device that introduces the material to be heated between the pressure member and conveys the heat of the heating body to the material to be heated via the heat resistant film by sandwiching and conveying the pressure contact nip portion together with the heat resistant film, The heating element includes a heat conductive substrate and a heating element formed on the substrate, and the center of the substrate in the widthwise direction is arranged on the heating material carry-in side with respect to the center of the pressure contact nip portion. A heating device characterized by the above. 7. The heating according to claim 5, wherein the material to be heated is a recording material on which an image is to be fixed, and an image heat fixing device for heating and fixing an unfixed image on the recording material. apparatus. 8. An image forming apparatus comprising the heating device according to claim 1 as an image heating fixing device for heating and fixing an unfixed image on a recording material. 9. A heating body, which comprises a substrate and a resistance heating element formed on the substrate as a basic constituent body and supplies electric power to the resistance heating element to generate heat, and with respect to a relative moving direction with respect to a heated object. A heating element having at least two peaks of heat generation distribution. 10. A heating body that includes a substrate and a resistance heating element formed on the substrate as a basic constituent body and supplies electric power to the resistance heating element to generate heat. comprising at least two of the perpendicular extending resistance heating element, the resistance of at least one resistance heating element and R _1, the resistance of the other of the at least one resistance heating element when the R _2, the relationship of R ₁ ≦ R ₂ A heating element characterized by being present. 11. A substrate and a resistance heating element formed on the substrate as a basic constituent body, which is a heating element for supplying electric power to the resistance heating element to generate heat, and with respect to a relative movement direction with respect to a heated object. A heating element comprising a resistance heating element extending at a right angle, and at least a part of the resistance heating element is disposed outside a pressure contact nip portion with a pressure member for pressing a material to be heated against the heating element. 12. A heating body, which comprises a substrate and a resistance heating element formed on the substrate as a basic constituent body and supplies electric power to the resistance heating element to generate heat, and with respect to a relative movement direction with respect to a heated object. A resistance heating element extending at a right angle is provided, and the center of the relative movement direction of the substrate with respect to the object to be heated is arranged at a position different from the center of the pressure contact nip portion with the pressing member for pressing the material to be heated with the heating member. A heating element characterized by being present.