JP2002033178A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device capable of preventing the side wherefrom heat is taken more from being lower than the other part in a heater having a heat-taking factor differed between both longitudinal ends thereof. SOLUTION: In this film heating device, a body to be heated introduced to a fixing nip part with the center orthogonal to a carrying direction as a carrying reference c is moved and passed integrally with a film 1, whereby the heating value of a heating element 1 is imparted to the body to be heated through the film 1. The heating element is set so that heating values per unit length in both ends 4a1 and 4a1 are differed from that of the center part, and the longitudinal lengths La1 and La2 of the parts having different heating value per unit length in both end parts 4a1 and 4a2 are differed laterally (La1<La2).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heating device for fixing a visible image such as a toner image formed on a heated member such as a recording material to the heated member, and a copying apparatus using the heating device as a fixing device. The present invention relates to an image forming apparatus such as a printer or a printer.

[0002]

2. Description of the Related Art Conventionally, as a heating device (fixing device) used in an electrophotographic image forming apparatus such as a copying machine and a laser beam printer, a heating roller fixing type is well known.

[0003] However, in this method, a high temperature must be maintained at all times, which consumes a large amount of energy and is contrary to energy saving. In addition, even during standby, heat is released into the machine, causing a problem of temperature rise in the machine.

In addition, it takes time to heat the roller to a temperature suitable for heating an object to be heated such as paper.

Japanese Patent Application Laid-Open No. 63-313182 discloses a method in which a pattern of a resistance heating element is provided on an insulating ceramic substrate to form a heater, and the heater is heated to heat the object to be heated via a thin film. It is proposed in the gazette.

According to this method, since the temperature of the heating body rises in a short time, even if the heated body is passed without warming up, the heated body as a paper sheet must reach the fixing nip. The heater can be heated to a required temperature. In addition, no heating is performed during standby, so there is no temperature rise inside the machine and no energy is consumed.

In the heating apparatus (fixing apparatus) of the film heating and fixing method, a bias is applied to the film in order to charge the film surface to a charge of a predetermined polarity. A conductive ring is provided at an end of the pressure roller disposed opposite to the film so as to contact the end of the film, and a bias is applied to the film via the conductive ring.

[0008]

However, in the above-described film heat fixing method, for example, since the heating element is in contact with the conductive ring on the end side, the heating element is connected to the end of the heating element via the conductive ring. Heat is easily taken away, and the amount of heat applied to the object to be heated may not be uniform in the nip.

Further, for example, when the factor for removing heat is different at both ends in the longitudinal direction of the heater, the temperature of the end on the side from which heat is removed is lower than that of other portions.

This phenomenon affects image quality such as poor edge fixing property, uneven fixing property, and uneven gloss when an image is formed.

The thermal conductivity of the substrate of the heating element is 10 to 30 [W
/ m · k], such a problem does not occur much, but the thermal conductivity is higher than this, for example, 50 to 150.
This is particularly likely to occur when a substance of [W / mk] is used as a heater substrate.

An object of the invention according to the present application is to solve the above-mentioned problem by a relatively simple method and to provide a heating apparatus and an image forming apparatus for forming a high-quality image.

[0013]

According to a first aspect of the present invention, there is provided a heating element comprising at least an insulating substrate and a resistance heating element, a film being pressed against and adhered to the heating element, and the film being slid on the surface of the heating element. A rotating pressurized body that is driven while moving, between the film and the pressurized body in the press-contact nip portion of the heated body and the pressurized body via the film, in the transport direction. In the heating device, the heating object is introduced to the heating object through the film by moving and moving the heating object introduced with the center in the direction orthogonal to the film integrally with the film. Is characterized in that the calorific value per unit length at both ends is different from that of the central portion, and the lengths in the longitudinal direction of the portions having different calorific values per unit length at both ends are different on the left and right.

According to a second aspect of the present invention, in the first aspect, the heating element is configured such that a heating value per unit length in a longitudinal direction at both ends of the resistance heating element is different from a central portion in a longitudinal direction. The feature is that the length near the end on the side where the length from the transfer reference to the end of the insulating substrate is longer is longer than the length near the other end.

[0015] In a third aspect based on the first aspect, the heating element is characterized in that the heating value per unit length in the longitudinal direction at both ends of the resistance heating element is different from that of the central portion in the longitudinal direction. The length of the stay near the end from the transfer reference to the end of the stay holding the insulating substrate is longer than the length near the other end.

[0016] In a fourth aspect based on the first aspect, the heating element is characterized in that the heating value per unit length in the longitudinal direction at both ends of the resistance heating element is different from the central portion in the longitudinal direction. As for the length, the length near the end where the length from the conveyance reference to the end of the pressing body is longer is longer than the length near the other end.

According to a fifth aspect of the present invention, in the first aspect, the heating element is configured such that a heating value per unit length in a longitudinal direction at both end portions of the resistance heating element is different from a central portion in a longitudinal direction. The length of the film near the end on the side where the length from the transport reference to the end of the film is longer is longer than the length near the other end.

According to a sixth aspect of the present invention, in any one of the above-mentioned aspects, a fan for taking in or exhausting air from the inside of the machine in which the heating device is incorporated is provided at the center of the longitudinal length of the object to be heated in the press-contact nip portion and at the conveyance. It is characterized in that it is attached to either the left or right with respect to the direction.

According to a seventh aspect of the present invention, in any one of the above aspects, the insulating substrate of the heating element has a thermal conductivity of 50 to 150 [W].
/ m · k].

According to an eighth aspect of the present invention, there is provided an image forming apparatus having any one of the above-mentioned heating devices as a fixing device, wherein the visible image formed by toner transferred to the recording material by the image forming means is fixed by the fixing device. It is in.

[0021]

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

(First Embodiment) FIG. 1 shows a first embodiment of the present invention.
An embodiment will be described. The present embodiment shows a case in which the length from the center C of the heated body, which is the center conveyance reference of the recording material, to the end of the heater substrate 3 is different on the left and right.

FIG. 1A shows a state in which a heater 7 is mounted on a stay 2 having a function of a heater holder as viewed from the nip surface side, and FIG. 1B shows a heater unit having the stay 2 mounted thereon. FIG. 5 is a schematic diagram showing a case where the positional relationship between the pressure roller 5 and the pressure roller 5 is viewed from the direction in which the heated body enters.

The heater 7 is formed by coating an electric resistance material such as Ag / Pd (silver palladium) on the surface of the heater substrate 3 made of alumina or the like to a thickness of about 10 μm and a width of 1 to 3 mm by screen printing or the like. Glass or fluororesin is coated thereon as a protective film, and the heater substrate 3 having a thermal conductivity of 50 to 150 [W / mk] is used.

The temperature in the sheet passing area is controlled by a temperature control device (not shown) so that the inside temperature becomes constant.

The stay 2 is made of a heat-resistant resin such as PPS, a liquid crystal polymer, and a phenol resin by molding. Also,
The film 1 has a total film thickness of 100 μm or less in order to reduce the heat capacity and improve the quick start property.
Preferably a single layer of PTFE, PFA, FEP or the like having a heat resistance, release property, strength, durability, etc. of 40 μm or less, 20 μm or more, or polyimide, polyamide imide, PE
PTFE / PFA on outer surface of EK / PES / PPS etc.
-A composite layer film coated with FEP or the like can be used. FIG. 7 shows a cross section at the center of the fixing device, and shows a state in which the recording material is heated by the heating device (fixing device) together with the toner on the recording material in the press-contact nip portion.

As shown in FIG. 1, the resistance heating element 4 of the present embodiment has a narrower width in the conveying direction of the heated body in the vicinity of the left and right ends 4a1, 4b1, so that the width is smaller than that in the center. A large amount of heat is generated per unit length in the longitudinal direction. The left side length from the heated object center C to the end of the heater substrate 3 is a
1. Assuming that the length on the right side is a2, in this case, since a1 <a2, the amount of heat flowing out from the vicinity of the end of the resistance heating element 4 without contributing to the fixing is larger on the right side. If the length from the center of the heating element to the end of the resistance heating element 4 is the same on the left and right, the fixability is poor near the right end.

In order to solve this problem, in the present embodiment, the amount of heat generated per unit length in the longitudinal direction of the left and right end portions 4a1 and 4a2 is larger than the amount of heat generated per unit length in the central direction in the central portion. are doing. In addition, the line width of the narrow resistance heating element 4 at the left and right ends 4a1 and 4a2 is made equal, and the length La2 of the right end 4a2 in the longitudinal direction is set.
Is made longer than the longitudinal length La1 of the left end 4a1, and the heat generation of the right end 4a2 of the resistance heating element 4 is made larger than the heat generation of the left end 4a1.

(Second Embodiment) FIG. 2 shows a second embodiment. This embodiment shows a case where the length from the heated object center C to the end of the stay 2 is different on the left and right.

FIG. 2 is a schematic diagram similar to the first embodiment. In the first embodiment, the case where the length from the heated object center C to the end of the heater substrate 3 is different on the left and right has been described.
In FIG. 2, the length from the heated object center C to the end of the heater substrate 3 is equal on the left and right sides. However, if the left side length to the end of the stay 2 is b1 and the right side length is b2, b1 <b2 Is assumed, the amount of heat flowing out from the vicinity of the end of the resistance heating element 4 without contributing to the fixing is larger on the right side because of the longer stay 2.

In this embodiment, similarly to the first embodiment, the amount of heat generated per unit length in the longitudinal direction at both ends 4b1 and 4b2 is calculated from the amount of heat generated per unit length in the longitudinal direction at the center. The amount of heat generated at the right end 4b2 is larger than the amount of heat generated at the left end 4b1.

In the present embodiment, of the two resistance heating elements 4 arranged in parallel, the length (Lb1, Lb2) of the left and right ends of one of the resistance heating elements 4 (upper side in the figure) is the same. (Lb1 = Lb2) and are formed to be narrow with the same line width, and the other resistance heating element 4 at the right end 4b2 also has a length L.
The line width is formed narrow over b3.

Therefore, the right end 4b2 is connected to the left end 4b1.
, The amount of heat generated in the portion of the length Lb3 increases. Also in this case, for the same reason as in the first embodiment, the length in the longitudinal direction of a portion where the amount of heat generated per unit length in the longitudinal direction in the vicinity of the end of the resistance heating element 4 is larger than that in the center is: It is substantially longer on the right side, which has more heat outflow than on the left side.

(Third Embodiment) FIG. 3 shows a third embodiment of the present invention.
An embodiment will be described. In the present embodiment, the heated object center C
The case where the length from the right to the end of the pressure roller 5 is different on the left and right.

FIG. 3 is a schematic view similar to that of the first embodiment. The end of the pressure roller 5 is in contact with the heater substrate 3 without the resistance heating element 4. Further, the pressure roller 5 rotates, and its surface is constantly in contact with air at a high speed, so that it is easily cooled. Therefore, the end of the resistance heating element 4 is connected to the heater substrate 3.
Large amount of heat easily escapes to the end of the pressure roller 5 through the pressure roller.
As shown in FIG. 3, assuming that the length from the heated object center C to the left end of the pressure roller 5 is c1 and the length from the right end is c2, the length relationship is c1 <c2.

The left end 4c1 and the right end 4c of the resistance heating element 4
2 is a notch, and the left and right ends 4c1 and 4c2 are cut at the same width and the same line width at both ends, so that the heat generation amount per unit length in the longitudinal direction of the central portion is left and right ends 4c1 and 4c2. And the length Lc2 of the right end 4c2 is made longer than the length Lc1 of the left end 4c1 while increasing the heat generation amount per unit length in the longitudinal direction.
The heat value of the right end 4c2 is larger than the heat value of the left end 4c1.

Also in this case, similarly to the above-described embodiment, since the pressure roller 5 is longer on the right side and the heat is likely to flow out of the heating body due to the longer length, the calorific value of the right end 4c2 is larger than that of the left end 4c1. The heat is uniformly applied to the object to be heated inside the nip.

The amount of heat generated per unit length in the longitudinal direction is the same as that of the central portion on both sides near the extreme end of the resistance heating element 4.

As shown in FIG. 8, the core metal 6 of the pressure roller 5
When a ring 11 made of conductive rubber or the like is attached to the end of the pressure roller 5 in order to apply a bias to the film 1 through the ring, the ring 11 is approximately the same size as the diameter of the pressure roller 5. In addition, since it is considered that the amount of heat flows from the film 1 even when it is not brought into contact with the pressure roller 5, if this is considered as a part of the pressure roller 5, as in this embodiment, the resistance heating element The object to be heated can be uniformly heated by making the length in the longitudinal direction of the portion where the amount of heat generated by the unit length in the longitudinal direction is larger than that in the center portion near the left and right end portions.

(Fourth Embodiment) FIG. 4 shows a fourth embodiment. This embodiment shows a case in which the length from the center of the object to be heated to the end of the film 1 is different on the left and right.

FIG. 4 is a schematic diagram similar to the first embodiment. Such a configuration is used when different flanges 9 are used on the left and right. The end of the film 1 is in contact with the heater substrate 3 having no resistance heating element 4. further,
The film 1 rotates, and its surface is in constant contact with air at a constant speed, so that it is easily cooled. Therefore, the resistance heating element 4
A large amount of heat easily escapes from the end of the film 1 to the end of the film 1 through the heater substrate 3.

In the present embodiment shown in FIG. 4, if the length from the center C of the object to be heated to the left end of the film 1 is d1, and the length from the right end to the right is d2, the relationship is d1 <d2. . In this case, heat is easily taken away by the film 1, and the temperature on the right side of the inner end of the nip is lower than that on the other side. In order to uniformly apply heat to the heated object inside the nip,
Left and right ends 4d with respect to the center C of the resistance heating element 4 to be heated
The line widths of 1, 4d2 are made narrower than the central portion, the heat generation amount per unit length in the longitudinal direction is made larger at the left and right end portions than at the central portion, and the length Ld2 of the right end portion 4d2 is made the left end portion 4d1.
Is longer than the length Ld1, and the amount of heat generated at the right end 4d2 is larger than the amount of heat generated at the left end 4d1.

(Fifth Embodiment) FIGS. 5 and 6 show a fifth embodiment of the present invention.

The fan 10 moves with respect to the center line C of the object to be heated.
The case where the camera is attached to either the left or right will be described.

Taking a laser beam printer as an example, the fan 10 is usually mounted on either the left or right of the center line C of the object to be heated in order to prevent the temperature inside the machine from rising and the humidity inside the machine from rising. .

FIG. 5 shows a laser beam printer viewed from a cross section. The fan 10 is mounted slightly upstream of the fixing device. FIG. 6 is a conceptual diagram when this configuration is viewed from above. Regardless of whether the fan 10 is the intake air or the exhaust air, the one near the fan 10 of the fixing device is likely to have a lower ambient temperature, so that it is considered that the amount of heat is easily released. For this reason, even if the way of escaping heat is not different between the right and left of the fixing device itself, there is a possibility that the influence of the fan 10 may appear on one side of the center of the heated object. Also in this case, the resistance heating element 4
By making the heat generation amount per unit length in the longitudinal direction near the right end portion near the center of the heated body longer than the length at the left end portion, the longitudinal length of the portion larger than the central portion,
Heat can be uniformly applied to the object to be heated inside the nip.

In the present embodiment, the width of the resistance heating element 4 near the end and the width of the resistance heating element at the center are constant in the left, right, upper and downstream directions, but may be changed in the left, right, upper and lower directions.

In each of the above embodiments, the stay 2 is formed with a recess for fitting the heater 7, but the stay 2 becomes smaller with the downsizing of the heating device. If heat stress occurs in -2, cracks may occur in the concave portions. However, in the embodiments of the present invention, such cracks can be prevented.

[0049]

As described above, according to the present invention, the unevenness of the amount of heat applied to the object to be heated due to the difference in the amount of heat flowing out can be made substantially uniform.

Further, 50-150
Since a substance having a high thermal conductivity of about [W / m · k] can be adopted, thermal stress generated inside the heater as a heating element can be reduced to prevent cracking.

[Brief description of the drawings]

FIG. 1 is a schematic view of a fixing device according to a first embodiment,
(A) is a figure which looked at the heater from the nip side, (b) is a front view.

FIG. 2 is a schematic diagram of a fixing device according to a second embodiment;
(A) is a figure which looked at the heater from the nip side, (b) is a front view.

FIG. 3 is a schematic diagram of a fixing device according to a third embodiment;
(A) is a figure which looked at the heater from the nip side, (b) is a front view.

FIG. 4 is a schematic diagram of a fixing device according to a fourth embodiment,
(A) is a figure which looked at the heater from the nip side, (b) is a front view.

FIG. 5 is a schematic diagram of a fixing device according to a fifth embodiment.

FIG. 6 is a schematic diagram of a fixing device according to a fifth embodiment.

FIG. 7 is a schematic diagram illustrating a cross section of the fixing device.

8A and 8B are schematic diagrams illustrating an example of use of a film bias ring, where FIG. 8A is a view of a heater viewed from a nip side, and FIG.
Is a front view.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Film 2 Stay (film guide) 3 Heater board 4 Resistance heating element 5 Pressure roller (Pressure body) 6 Core metal 7 Heater 8 T stay 9 Flange (Film guide) 10 Fan 11 Conductive ring

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H027 JA11 JB13 JB16 JC08 2H033 AA03 AA10 BA25 BA26 BA27 BA29 BE03 CA53 3K058 AA86 BA18 CE02 CE13 CE17 CE19 CE21 CE29 DA05 DA06 GA06 3K092 PP08 PP18 QA02 QA05 QB02 QB QB QB QB QB QB Q QB75 QB76 RA02 RA06 RD28 RF03 RF11 RF17 RF22 VV22

Claims (8)

[Claims] 1. A heating element comprising at least an insulating substrate and a resistance heating element, and a film press-contacted to said heating element,
And a rotary pressurizing body which is driven to move while sliding the film on the surface of the heating body, wherein the film and the film at a press-contact nip portion of the heating body and the pressurizing body which are pressed against each other via the film. The heat quantity of the heating body is heated through the film by moving and moving the heating body, which is introduced with the center in the direction orthogonal to the conveyance direction as the conveyance reference, integrally with the film, between the pressure body and the pressure body. In the heating device applied to the body, the heating element has a heating value per unit length at both ends different from that of the central portion, and a longitudinal length of a portion having a different heating value per unit length at the both ends. Is different between the left and right. 2. The heating element according to claim 1, wherein a length of the heating element per unit length in a longitudinal direction at both ends of the resistance heating element is different from that of a central part in a longitudinal direction, based on the transfer reference. Near the end where the length to the end is longer,
The heating device according to claim 1, wherein the length is longer than a length near the other end. 3. The heating element according to claim 1, wherein a length in a longitudinal direction of a portion different from a central portion in a heat generation amount per unit length in a longitudinal direction at both end portions of the resistance heating element is determined based on the transport reference. 2. The heating device according to claim 1, wherein the length near the end of the stay holding the stay is longer near the other end than the length near the other end. 4. The heating element is characterized in that the longitudinal length of a portion of the resistive heating element at both ends where the amount of heat generated per unit length in the longitudinal direction is different from that of the central portion is determined from the conveyance reference by the pressing element. 2. The heating device according to claim 1, wherein the length near the end on the side where the length to the end is longer is longer than the length near the other end. 5. The heating element is characterized in that the longitudinal length of a portion where the amount of heat generated per unit length in the longitudinal direction at both ends of the resistance heating element is different from that of the central portion is determined from the conveyance reference to the end of the film. The heating device according to claim 1, wherein the length near the end on the longer side is longer than the length near the other end. 6. A fan for taking in or exhausting air from the inside of the machine in which the heating device is incorporated is attached to the center of the longitudinal length of the object to be heated in the press-contact nip portion and to one of the right and left sides with respect to the conveying direction. The heating device according to any one of claims 1 to 5, wherein 7. The heating apparatus according to claim 1, wherein the insulating substrate of the heating body has a thermal conductivity of 50 to 150 [W / m · k]. 8. A fixing device comprising the heating device according to claim 1, wherein a visible image of toner transferred to a recording material by an image forming means is fixed by the fixing device. Image forming device.