JP2002033177A - Heating device and image forming device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heating device capable of preventing the temperature of the end part on the side from which 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 heater 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 7 is imparted to the body to be heated through the film 1. The heating element 7 has heat insulating effect parts 11A1 and 11A2 having a heat insulating effect different from the other part on both ends of a stay 2 for retaining an insulating board 3, and the heat insulating effect is differed between the lateral heat insulating effect parts 11A1 and 11A2.

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 / m · k] 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 a stay for holding the insulating substrate has a heat insulating effect portion having a different heat insulating effect from the other portions at both ends, and the left and right heat insulating effect portions have different heat insulating effects.

According to a second aspect, in the first aspect, the heat insulating effect portion is formed by a recess.

According to a third aspect of the present invention, in the first aspect, the heating element has a longer end from the transfer reference to the end of the insulating substrate than the other end. The heat insulating effect of the heat insulating effect portion near the stay end is large.

[0016] In a fourth aspect based on the first aspect, the heating element has a longer end on the side from the transfer reference to the end of the stay than the other end. The heat insulating effect of the heat insulating effect portion near the stay end is large.

In a fifth aspect based on the first aspect, the heating element has a longer end from the conveyance reference to the end of the pressing body than the other end. The heat insulating effect of the heat insulating effect portion in the vicinity of the stay end is large.

In a sixth aspect based on the first aspect, the heating element is such that an end on the longer side from the transport reference to the end of the film has a greater length than the other end. The heat insulating effect of the heat insulating effect portion near the stay end is large.

According to a seventh 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 arranged so that the fan is located at the center of the longitudinal length of the object to be heated in the press-contact nip and is conveyed. It is characterized in that it is attached to either the left or right with respect to the direction.

In an eighth aspect based on any of the above aspects, the insulating substrate of the heating element has a thermal conductivity of 50 to 150 [W].
/ m · k].

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

[0022]

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

(First Embodiment) This embodiment shows a case where the length from the center C of the object to be heated to the end of the heater substrate 3 is different on the left and right as shown in FIG.

FIG. 9A 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. 9B shows a heater unit in which the stay 2 is mounted. 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 formed by molding with a heat resistant resin such as PPS, liquid crystal polymer, phenol resin and the like. Further, the film 1 has a film thickness of 100 μm or less in total, preferably 40 μm or less, and preferably 20 μm or more in terms of heat resistance, release property, strength, durability, etc., in order to reduce the heat capacity and improve the quick start property. Single layer of PTFE, PFA, FEP, etc., or polyimide, polyamide imide, PEE
PTFE, PFA, etc. on the outer surface of K, 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 medium is heated by the heating device (fixing device) together with the toner on the recording medium in the press-contact nip portion.

FIG. 1A shows a heater substrate 3 as an insulating substrate provided with a resistance heating element 4, and FIG.
Is shown, and the heater substrate 3 is provided on the stay 2.
Is formed, and a heater as a heating element is formed by fitting the heater substrate 3 into the stay 2.

This heater has a recess 2a in a frame indicated by a two-dot chain line when the stay 2 is viewed from the nip surface side in FIG.
Attached to. Although the length relationship is different, FIG. FIG. 1C is substantially the same as FIG. 9B.

As shown in FIG. 1B, left and right depressions 11A1 and 11A2 are formed on the bottom of the recess 2a of the stay 2 (shown in black in the figure).
These left and right depressions 11A1 and 11A2 are provided corresponding to the left and right ends of the resistance heating element 4. The left and right depressions 11A1 and 11A2 are formed such that opposing portions facing each other are pointed, and the length of the right depression 11A2 is longer than the left depression 11A1. Hollow 11A
FIG. 8 is a schematic view of the device 1 as viewed obliquely from an enlarged view.

On the other hand, as shown in FIG. 1C, the length from the center c of the object to be heated to the end of the heater substrate 3 is represented by a1, a1 on the left side.
Assuming that a2 is on the right side, the length relationship is a1 <a2. In this case, since the amount of heat flowing out of the resistance heating element 4 at the end is considered to be larger on the right side than on the left side, in the present embodiment, the recesses 1 provided near both ends of the stay 2 are provided.
In FIG. 1, the right recess 11 is larger than the left recess 11A1.
The heat insulation effect of A2 is increased.

In the case of this embodiment, the right recess 11A
As a method for enhancing the heat insulating effect in Step 2, as shown in FIG. 11, the width and depth of the depression are the same (αa1 = αa2, δa1).
= Δa2), and the length in the longitudinal direction was increased (Aa1 <A
a2).

Naturally, the area of the right recess 11A2 is larger. Left and right recesses 11 near the stay end
Both A1 and 1A2 protrude outside the resistance heating element 4. By providing the recesses 11A1 and 11A2 having different lengths (areas) on the right and left in the vicinity of the stay end, heat can be prevented from flowing out from the end of the resistance heating element 4 and the object to be heated can be uniformly formed in the nip. Can be heated.

(Second Embodiment) FIG. 2 shows a second embodiment of the present invention.
An embodiment will be described. This embodiment shows a case where the length from the center of the body to be heated to the end of the stay 2 is different on the left and right.

FIG. 2 is a schematic view similar to FIG. 1 and shows a case in which the length from the center C of the object to be heated to the end of the heater substrate 3 is different between the left and right in the first embodiment. In the illustrated embodiment, the length from the heated object center C to the end of the heater substrate 3 is equal in the left and right directions, but the length from the center C to the left and right ends of the stay 2 is b1 and b2, respectively. b1 <
Since the length relationship of b2 is assumed, the amount of heat flowing out of the resistance heating element 4 is considered to be larger on the right side as the stay 2 is longer.

In this embodiment, as in the first embodiment, recesses 11B1 and 11B2 having different heat insulation effects are provided near the left and right ends of the stay 2 in the vicinity.

Then, heat is prevented from flowing out from the end of the resistance heating element 4 due to the length of the stay 2, so that heat is uniformly applied in the longitudinal direction of the heated object inside the nip.

In the present embodiment, as shown in FIGS. 2 and 12, the lengths and widths (areas of planes) of the left and right depressions 11B1 and 11B2 are the same on the left and right (Ab1 = Ab2, αb1 = α).
b2), the depth is made deeper in the right indent 11B2 than in the left indent 11B1 (δb1 <δb2), and the volume is made different, so that the heat insulation effect is made different.

As described above, by providing a deeper (larger volume) recess near the end of the stay 2 where the heat escapes more, the heat insulation effect is increased, and the object to be heated can be uniformly distributed in the nip. Can be heated.

(Third Embodiment) FIG. 3 shows a third embodiment. This embodiment shows a case where the length from the heated object center C to the end of the pressure roller 5 is different on the left and right.

FIG. 3 is a schematic diagram similar to that of the first embodiment shown in FIG. 1, in which the end of the pressure roller 5 is in contact with the heater substrate 3 having no 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, a large amount of heat easily escapes from the end of the resistance heating element 4 to the end of the pressure roller 5 through the heater substrate 3. In FIG. 3, if the length from the heated object center C to the left and right ends of the pressure roller 5 is c1 and c2 on the left and right, respectively, the relationship is c1 <c2.

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 apt to flow out of the heater 5 because of the longer length, the heat insulation effect by the recesses 11C1 and 11C2 is reduced by the right side rather than the left side. Otherwise, heat is not uniformly applied to the object to be heated inside the nip.

In order to increase the heat insulating effect of the right recess 11C2 more than that of the left recess 11C1, as shown in FIGS. 3 and 13, the width of the recess (αc1 <αc2) is widened to the right. The other dimensions are equal (length: Ac1 = Ac2, depth: δc1 = δc2). By doing so, the plane area is increased (the volume is increased), and the outflow of heat from the resistance heating element 4 at the right end can be prevented.

As shown in FIG. 10, a ring 12 made of conductive rubber or the like is attached to the end of the pressure roller 5 to apply a bias to the film via the metal core 6 of the pressure roller 5. In this case, the ring 12 is almost the same size as the diameter of the pressure roller 5, and even if it does not come into contact with the pressure roller 5, it is considered that heat flows from the film 1 so that Assuming that the recess 11 is a part, the recess 11 may be provided in the vicinity of the end of the stay 2 so that the heat insulating effect is different between the left and right similarly to the present embodiment.

(Fourth Embodiment) FIG. 4 shows a fourth embodiment of the present invention.
An embodiment will be described. In the present embodiment, the heated object center C
This shows a case where the length from to the end of the film 1 is different between the left and right.

FIG. 4 is a schematic diagram similar to the first embodiment shown in FIG. 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. Furthermore, the film 1 rotates and its surface is constantly in contact with air at a high speed, so that it is easy to cool. Therefore,
A large amount of heat easily escapes from the end of the resistance heating element 4 to the end of the film 1 through the heater substrate 3.

In the present embodiment shown in FIG. 4, the length from the center C of the object to be heated to the edge of the film 1 is left and right, respectively.
Assuming that 1 · d2, there is a relationship of d1 <d2.

In this case, heat is easily taken away at the right end of the film 1, and the temperature of the right side of the inner end of the nip is lower than that of the other parts.

Therefore, similarly to the above embodiments, the recesses 11D1 and 11D2 are provided near both ends of the stay 2, so that the right recess 11D2 can obtain a more heat insulating effect.

In the case of the present embodiment, as shown in FIGS. 4 and 14, the shapes of the left and right depressions 11D1 and 11D2 are greatly different. The left and right depressions 11D1 and 11D2 are
The length, width and depth are the same (Ad1 = Ad2, αd1 = αd
2, δd1 = δd2), but the left hollow 11D1
Is a pointed wedge, the right recess 11D2 is an ellipse,
Due to the difference in shape between the two, the right hollow 11D2 has a larger area and volume and a smaller contact area with the heater 7, so that the heat insulating effect is larger.

With this configuration, it is possible to prevent heat from escaping from the end of the resistance heating element 4 near the right end of the stay 2 and to uniformly heat the object to be heated in the nip.

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

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

Taking a laser beam printer as an example, the fan 10 is usually mounted on the left or right with respect to 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. Fan 1
Reference numeral 0 is attached slightly upstream of the fixing device. FIG. 6 is a conceptual diagram when this configuration is viewed from above. Fan 1
Regardless of whether the value of 0 is the intake air or the exhaust gas, the temperature near the fan 10 of the fixing device is likely to be low, 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 be exerted on one side of the center of the heated object. Also in this case, a recess 11 is provided near the end of the stay 2 on the side where heat is easily taken away by the fan 10 so that a heat insulating effect can be obtained from the other end, for example, as in the above embodiments. Thus, heat can be uniformly applied to the object to be heated inside the nip.

In the embodiment described above, the number of the recesses 11 is two at both ends in one stay 2.
In some cases, the number may be increased. That is, a large number of fine depressions 11 may be displayed. Regarding the shape, it is only necessary to select a shape such that heat is easily released from the end of the resistance heating element 4 and the heat insulating effect by the recess 11 can be obtained more than the other end.

In each of the above-described embodiments, the stay 2 is formed with a concave portion 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.

[0057]

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 plan view of a heater substrate, (b) is a plan view of a stay, and (c) is a front view of a fixing device.

FIG. 2 is a schematic diagram of a fixing device according to a second embodiment;
(A) is a plan view of a heater substrate, (b) is a plan view of a stay, and (c) is a front view of a fixing device.

FIG. 3 is a schematic diagram of a fixing device according to a third embodiment;
(A) is a plan view of a heater substrate, (b) is a plan view of a stay, and (c) is a front view of a fixing device.

FIG. 4 is a schematic diagram of a fixing device according to a fourth embodiment,
(A) is a plan view of a heater substrate, (b) is a plan view of a stay, and (c) is a front view of a fixing device.

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.

FIG. 8 is a perspective view of the stay in FIG. 1;

9A is a schematic view of a heater, and FIG. 9B is a front view of a fixing device.

FIG. 10 is a schematic view showing an example of using a conductive rubber ring;
(A) is a schematic diagram of a heater, (b) is a front view of a fixing device.

FIG. 11 is an enlarged perspective view of an end of the stay of FIG. 1;

FIG. 12 is an enlarged perspective view of an end of the stay of FIG. 2;

FIG. 13 is an enlarged perspective view of an end of the stay of FIG. 3;

FIG. 14 is an enlarged perspective view of an end of the stay of FIG. 4;

[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 Recess 12 Conductive rubber ring

 ──────────────────────────────────────────────────続 き Continuing on the front page F term (reference) 2H033 AA03 AA10 BA05 BA26 BE03 3K058 AA02 AA22 AA86 BA18 CA12 CA23 CA46 CE02 CE13 CE17 DA04 GA06 3K092 PP18 QA06 QB02 QB33 QB76 QC25 RF03 RF11 RF12 RF14 RF17 RF26 V04 V31 V04

Claims (9)

[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 provided to a body, the heating body has a heat insulating effect portion having a different heat insulating effect from other portions at both ends of a stay holding the insulating substrate, and heat insulation at the left and right heat insulating effect portions. A heating device characterized by different effects. 2. The heating device according to claim 1, wherein the heat insulating effect portion is formed by a depression. 3. The heat-insulating effect of the heat-insulating effect portion in the vicinity of a stay end at an end portion having a longer length from the transfer reference to the end of the insulating substrate than the other end portion. The heating device according to claim 1, wherein is larger. 4. The heat-insulating effect of the heat-insulating effect portion in the vicinity of the stay end at the end having a longer length from the conveyance reference to the end of the stay than at the other end. The heating device according to claim 1, wherein is larger. 5. The heat-insulating portion of the heating element near the stay end near the end where the length from the conveyance reference to the end of the pressing body is longer than the other end. The heating device according to claim 1, wherein the heat insulating effect is large. 6. The heat-insulating portion of the heat-insulating effect portion is closer to the stay end at the end having the longer length from the transport reference to the end of the film than at the other end. The heating device according to claim 1, wherein the effect is large. 7. 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 either the left or right with respect to the transport direction. The heating device according to any one of claims 1 to 6, wherein 8. 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]. 9. A fixing device comprising the heating device according to claim 1, wherein a visible image formed by toner transferred to a recording material by an image forming unit is fixed by the fixing device. Image forming device.