JP2002139942A - Fixing roll and fixing device provided with fixing roll - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a fixing roll where sufficient mechanical strength can be secured and the rising time can be greatly shortened. SOLUTION: In a fixing roll, a toner image is heat melted by a heating source outside a core metal and melt stuck to transfer material by being abutted to a press roll at a specified pressure and having the transfer material where the toner image is transferred inserted between the fixing roll and the press roll. The fixing roll is provided with the core metal 1 and a mold release layer 4 on the core metal 1 and an insulating layer 2 that is in between the core metal 1 and the core release layer 4 as well as being between the core metal 1 and the heating source.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an electrophotographic copying machine,
The present invention relates to a fixing roller used for an apparatus using an electrophotographic process, such as a facsimile and a printer, and a fixing device having the fixing roller.

[0002]

2. Description of the Related Art As a fixing device of an electrophotographic apparatus, there is known a fixing device including a heating roller as a fixing roller and a pressure roller for pressing the heating roller. In this fixing device, a sheet carrying a developer image composed of a powder developer passes through a nip portion between a heating roller and a fixing roller, so that the developer on the sheet is melt-pressed and fixed. Conventionally, as a fixing roller heated from the outer peripheral side, JP-A-2000-1
No. 81258 is known. This fixing roller generates Joule heat by an excitation coil arranged on the outer peripheral surface,
It is heated by this Joule heat.

[0003]

However, in the conventional fixing roller heated from the outer peripheral side, when the thickness of the fixing roller is increased in order to increase the rigidity, there is a problem that the rise time is delayed. When the thickness of the fixing roller is reduced in order to shorten the rise time, the heat capacity is reduced and the rise is quickened, but the thinning deteriorates the mechanical strength deflection, as shown in the nip shape in FIG. In addition, there is a problem that the nip width in the central portion is narrowed and the fixing property is deteriorated.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a fixing roller having a sufficient mechanical strength and a significantly reduced rise time, and a fixing device having the fixing roller.

[0005]

Means for Solving the Problems In order to achieve the above object, the invention according to claim 1 is to contact a pressure roller with a predetermined pressure,
A fixing roller that heats and fuses the toner image from a heating source outside the cored bar and fuses the toner image onto the transfer material by inserting a transfer material onto which the toner image has been transferred through the pressing roller. At
The fixing roller has a cored bar and a release layer on the cored bar, and is insulated between the cored bar and the release layer, and between the cored bar and the heating source. A fixing roller provided with a layer. In this configuration, since the core and the heat source are insulated by the heat insulating layer, the core is not affected by the heat capacity of the core at the time of rising, and the core can be thickened, and sufficient strength can be obtained. As a result, the rise of the temperature can be accelerated, and the deterioration of the fixing property due to the narrow nip width can be prevented.

According to a second aspect of the present invention, in the fixing roller according to the first aspect, a release layer substrate is provided between the release layer and the heat insulating layer.
In this configuration, since the core metal and the release layer substrate are insulated by the heat insulating layer, the core metal can be made thicker than the release layer substrate without affecting the rising, and sufficient strength can be obtained. Thus, the release layer substrate can be made thinner, the rise of the temperature can be made faster, and the deterioration of the fixing property due to the narrow nip width can be prevented. Further, since the release layer is formed on the release layer substrate, the range of selection as the heat insulating layer is extremely wide.

According to a third aspect of the present invention, in the fixing roller according to the second aspect, the core metal is fixed in a thrust direction at a step-shaped portion of the release layer substrate. . In this configuration, since the metal core and the release layer substrate are fixed in the thrust direction, the heat insulation layer between the metal core and the release layer substrate may cause the core metal and the release layer substrate to be misaligned. Absent.

According to a fourth aspect of the present invention, in the fixing roller according to any one of the second to third aspects, the thickness of the release layer substrate is smaller than that of the cored bar. In this configuration, the thickness of the release layer substrate is made thinner than the core metal, and the rise time can be shortened, and the mechanical strength can be imparted to the core metal, thereby shortening the rise time and making the nip width uniform. Can be compatible.

According to a fifth aspect of the present invention, in the fixing roller according to any one of the first to fourth aspects, the heat insulating layer is formed such that both ends are thicker than a central portion thereof. It is characterized by having. With this configuration, the temperature distribution at the time of rising can be made uniform between the central portion and the end portion, and it is possible to prevent the end fixing property of the first and second sheets immediately after the rising from deteriorating.

According to a sixth aspect of the present invention, in the fixing roller according to any one of the second to fifth aspects, the linear expansion coefficient of the core metal is equal to that of the release layer substrate. .
With this configuration, loosening of the core metal and deformation of the release layer substrate due to a difference in linear expansion coefficient between the core metal and the release layer substrate can be prevented.

Further, according to a seventh aspect of the present invention, a toner image is transferred to a center by contacting the pressure roller with a predetermined pressure and inserting a transfer material on which the toner image is transferred between the pressure roller and the pressure roller. In a fixing device provided with a fixing roller that heats and melts from a heat source outside of gold and fuses on a transfer material, the fixing roller includes:
A core bar, and a release layer on the core bar, a heat insulation layer is provided between the core bar and the release layer, and between the core bar and the heating source. And a fixing device provided with a fixing roller. In this configuration, since the core metal and the release layer substrate are insulated by the heat insulating layer, the core metal can be made thicker than the release layer substrate without affecting the rising, and sufficient strength can be obtained. In addition, the release layer substrate can be made thinner, the rise of the temperature can be made faster, the deterioration of the fixing property due to the narrow nip width can be prevented, and the warm-up time and heating The driving time of the source can be shortened together with the effect of saving energy.

[0012]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a longitudinal sectional view of the fixing roller according to the first embodiment of the present invention. As shown in FIG. 1, the fixing roller 10 includes a hollow cylindrical cored bar 1, a heat insulating layer 2 formed on the cored bar 1 in a hollow cylindrical shape, and a hollow cylindrical separating bar on the heat insulating layer 2. It comprises a mold layer base 3 and a release layer 4 formed in a hollow cylindrical shape on the release layer base 3.

The metal core 1 and the release layer substrate 3 are both made of a metal material. Specifically, a metal material such as an aluminum alloy, a copper alloy, iron, and stainless steel is used.
By selecting a material having a linear expansion coefficient equal to or close to that of the core metal 1 and the release layer substrate 3, it is possible to prevent the release metal substrate 1 from expanding relative to the core metal 1 and loosening the core metal. Core 1
Can be prevented from expanding with respect to the release layer substrate 3 and deforming the release layer substrate 3 so that the outer diameter and runout deviate from the drawing tolerance.

The heat insulating layer 2 is made of a heat-resistant material such as ceramic felt and rock wool having heat resistance. The release layer 4 is formed to a thickness of 10 to 30 μm,
(Perfluoroalkoxy), PTFE (polytetrafluoroethylene) or a mixture thereof.

As a heating source disposed outside the core bar 1, a non-contact type halogen lamp or the like which heats from outside the fixing roller 10 can be used in addition to the electromagnetic induction heating as in the prior art. As the contact type, a planar heat source, a ceramic heater, or the like can be used.
When using this contact type, the heating source is disposed between the heat insulating layer 2 and the release layer 4.

According to the fixing roller 10 of the first embodiment,
Since the core metal 1 and the release layer substrate 3 are insulated by the heat insulating layer 2, the core metal 1 can be made thicker than the release layer substrate 3 without affecting the rising, and sufficient strength can be obtained. Can be. In this case, the cored bar 1 may be solid. As described above, since sufficient mechanical strength can be obtained by increasing the thickness of the cored bar 1, the release layer substrate 3 can be thinned, and the rise of the temperature can be accelerated. For example, the thickness of the release layer substrate 3 can be set to 1 mm or less, and the rise time can be greatly reduced.

FIG. 2 is a diagram showing a method of manufacturing the fixing roller of FIG. As shown in FIG. 2, first, the inner surface of the cored bar 1 is held by a mandrel jig 20, and then a spinning roller 21 is pressed against one side of the outer peripheral surface of the release layer substrate 3, and the other side (spinning roller). A backup roller 22 for preventing deformation of the outer peripheral surface of the release layer substrate 3 is brought into contact with the roller 21 (on the side facing the roller 21).

Next, the backup roller 22 is rotated, and the spinning roller 21 is rotated and moved along the outer peripheral surface of the release layer substrate 3 to perform a spinning process. By reducing the diameter, the heat insulating layer 2 is pressed and the core metal 1 and the release layer substrate 3 are fixed.

As described above, since the heat insulating layer 2 is provided between the cored bar 1 and the release layer substrate 3, the mechanical strength of the cored bar 1 can be sufficiently ensured. As a result, since the core metal 1 has mechanical strength, even if the release layer substrate 4 is made thinner, a sufficient nip width at the center can be ensured as shown in FIG. As a result, defective fixing can be prevented.

FIG. 4 is a view showing a main part of a fixing roller according to a second embodiment of the present invention. FIG. 4A is an enlarged sectional view of a main part of the fixing roller immediately after spinning, and FIG. FIG. 4 is an enlarged sectional view of a main part of the fixing roller after cutting the diameter to a predetermined diameter.

As shown in FIG. 4, the structure of this fixing roller is the same as that of the first embodiment, except that the diameter of the release layer substrate 3 outside the cored bar 1 is reduced by spinning. The difference is that the amount is increased and that the thickness of the core bar 1 is larger than that of the release layer substrate 3.

As shown in FIG. 4A, after the spinning process is performed so that the inner diameter of the end portion side of the release layer substrate 3 is smaller than the outer diameter of the core bar 1, the outer portion of the release layer substrate 3 is formed. 3a is removed by cutting to obtain a predetermined diameter. As a result, as shown in FIG. 4B, the thickness of the part of the release layer substrate 3 located outside the end of the cored bar 1 is increased. The core 1 is sandwiched by the thick portion 3b whose inner diameter is smaller than the outer diameter of the core 1, and cannot move in the thrust direction. Thereafter, the release layer 4 is coated on the outer periphery of the release layer substrate 3.

According to the fixing roller of the second embodiment,
Even if the heat insulating layer 2 is provided between the core metal 1 and the release layer substrate 3, the core metal 1 and the release layer substrate 3 do not shift in the thrust direction.

FIG. 5 is a diagram showing the rise time of the fixing roller. As shown in FIG. 5, by setting the thickness t [mm] of the heat insulating layer 2 in the range of 0.5 <t ≦ 5 in the fixing roller of FIG. It is possible to prevent the material cost from increasing by increasing the thickness of the heat insulating layer 2.

The thickness of the heat insulating layer 2 is less than 0.5 mm (FIG. 5).
When the thickness is set to medium, t <0.5, the heat-insulating material 2 is compressed and the rise time hardly changes from the case without the heat-insulating layer 2, and exceeds 5 mm (the line of t ≧ 5 in FIG. 5). However, since the rise time does not change from the case of 5 mm, the heat insulating layer 2 is unnecessarily thickened.

FIG. 6 is a diagram showing a modification of the fixing roller of FIG. As shown in FIG. 6, the fixing roller in FIG. 4 (B) does not have the same diameter in the axial direction, that is, does not make it straight, but passes the end bearing, that is, the diameter D2 of the journal 3c. By making the diameter smaller than the diameter D1 of the region, the diameter of the bearing can be reduced, so that the apparatus can be downsized.

FIG. 7 is a diagram showing a main part of a fixing roller according to a third embodiment of the present invention, and FIG. 8 is a diagram showing a temperature distribution immediately after rising. As shown in FIG. 7, the basic configuration of the fixing roller is the same as that of the fixing roller shown in FIG. 4B, except for the thickness of the heat insulating layer 2 and the thickness of the metal core 1. That is, the thickness of the heat insulating layer 2 is made thicker at both ends than the thickness of the heat insulating layer Ct at the center, and the thickness of the core bar 1 is made thinner at both ends than at the center.

With such a configuration, the heat insulating effect changes between the center and the end. Specifically, when the thickness of the heat insulating layer 2 is small, the heat of the heating element escapes to the metal core 1 on the inner peripheral surface, so that the temperature rise is delayed. Since heat hardly escapes to the core metal 1 on the inner peripheral surface, the temperature rises quickly. Therefore, as shown in FIG. 8, the temperature distribution immediately after the rise is different from the rise curve C2 in the case where the heat insulating layer having a uniform thickness is provided, after the thickness of the heat insulating layer 2 is changed as shown in FIG. Is improved in the axial direction as shown by the rising curve C1.

That is, in the case of the curve C1, the heat conduction from the heating element to the metal core 1 is different in the axial direction. The amount of heat that escapes can be compensated for, and the temperature at the time of rising becomes the same at the center and at the end, so that the fixing property of the end of the first and second sheets immediately after the start of the fixing roller is improved.

FIG. 10 is an explanatory view showing the main structure of an electrophotographic image forming apparatus such as a copying machine, a printer, a facsimile, etc., provided with the fixing roller according to the present invention. FIG.
As shown in FIG. 1, the image forming apparatus includes a photosensitive drum 54a on which an electrostatic latent image is formed, and a photosensitive drum 54a.
Roller 54b that performs charging processing in contact with or in close proximity to
A developing roller 54e for applying toner to the electrostatic latent image on the photosensitive drum 54a, a power supply 54h for applying a DC voltage to the charging roller 54e, and a toner image on the photosensitive drum 54a being conveyed from a paper feeding unit. A transfer roller 54f for performing transfer processing on the transferred transfer paper P, and a cleaning device 54 for removing and collecting residual toner on the surface of the photosensitive drum 54a.
g, a surface voltmeter 54 d for measuring the surface potential of the photosensitive drum 54 a, and a fixing device 40 having the fixing roller 10 and the pressure roller 30. Reference numeral 54c indicates exposure such as laser light or reflected light of a document.

An image forming operation in the image forming apparatus configured as described above will be described. First, the surface of the photosensitive drum 54a is uniformly charged to a high potential by supplying a DC voltage from the power supply 54h to the charging roller 54b which is in contact with the photosensitive drum 54a.

Immediately thereafter, when the surface of the photosensitive drum 54a is exposed 54c, the potential of the exposed portion decreases. Since the exposure 54c has a light amount distribution corresponding to the density of the image, the exposure 54c forms a potential distribution for the recorded image, that is, an electrostatic latent image on the surface of the photosensitive drum 54a.

Next, when the portion on which the electrostatic latent image is formed passes through the developing roller 54e, toner adheres according to the level of the potential, and a toner image is formed by visualizing the electrostatic latent image. You. Next, the transfer paper P is conveyed at a predetermined timing to a portion where the toner image is formed, and overlaps the toner image. After the toner image is transferred onto the transfer sheet P by the transfer roller 54f, the transfer sheet P is separated from the photosensitive drum 54a.

Next, the separated transfer paper P is conveyed through a conveyance path, is fixed by heat and pressure by a fixing roller 52 and a pressure roller 53, and is then discharged out of the apparatus. After the completion of the transfer, the surface of the photosensitive drum 54a is cleaned by a cleaning device 54g, and the residual charge is erased by a residual charge erasing means (not shown) to prepare for the next image forming process.

FIG. 11 is a view showing the use state of the fixing roller of the above embodiment used in the image forming apparatus of FIG. As shown in FIG. 11, a fixing roller 10 used in this image forming apparatus includes a heat generating device (not shown) such as an electromagnetic induction heating source, a halogen lamp, a sheet heating source, and a ceramic heater outside a cored bar. The nip portion N is provided and is in pressure contact with the pressure roller 30. The fixing roller 2 melts and fixes the toner T on the transfer paper P sent to the nip N by the pressure of the nip N and the radiant heat from the heat generating device.

At this time, as described above, since the fixing roller having the release layer substrate which is thermally isolated from the core metal by the heat insulating layer and has a reduced thickness is used as the fixing roller, the rate of temperature rise of the fixing roller is as follows. , The rise time can be greatly reduced, and power saving can be achieved. That is, both the warm-up time and the drive time of the heating source can be reduced. Note that the present invention is not limited to the above embodiment. That is, various modifications can be made without departing from the gist of the present invention.

[0037]

As described above, according to the first aspect of the present invention, the core can be thickened without being affected by the heat capacity of the core at the time of rising, and sufficient strength can be obtained. As a result, the rise of the temperature can be accelerated, and the deterioration of the fixing property due to the narrow nip width can be prevented.

According to the second aspect of the present invention, the core metal can be made thicker than the release layer substrate without affecting the rise, sufficient strength can be obtained, and the release layer substrate can be made thin. As a result, the rise of the temperature can be accelerated, and the deterioration of the fixing property due to the narrow nip width can be prevented. Further, since the release layer is formed on the release layer substrate, the range of selection as the heat insulating layer is extremely wide.

Further, according to the third aspect of the present invention, it is possible to prevent displacement of the core metal and the release layer substrate due to the heat insulating layer between the core metal and the release layer substrate. Further, according to the invention of claim 4, it is possible to achieve both a reduction in the rise time and a uniform nip width.

Further, according to the fifth aspect of the present invention, it is possible to prevent the end fixing properties of the first and second sheets immediately after rising from deteriorating. According to the invention of claim 6,
The loosening of the core metal and the deformation of the release layer substrate due to the difference in the linear expansion coefficient between the core metal and the release layer substrate can be prevented.

According to the seventh aspect of the present invention, the core metal can be made thicker than the release layer substrate without affecting the rise, sufficient strength can be obtained, and the release layer substrate can be made thin. The temperature rise can be accelerated, the deterioration of fixability due to the narrow nip width can be prevented, and both the warm-up time and the driving time of the heating source can be shortened. This has the effect of saving energy.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of a fixing roller according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating a method of manufacturing the fixing roller of FIG.

FIG. 3 is a diagram illustrating a shape of a nip portion of the fixing roller of FIG. 1;

4A and 4B are diagrams illustrating a main part of a fixing roller according to a second embodiment of the present invention, in which FIG. 4A is an enlarged cross-sectional view of the main part of the fixing roller immediately after spinning, and FIG. FIG. 4 is an enlarged sectional view of a main part of the fixing roller after cutting to a predetermined diameter.

FIG. 5 is a diagram illustrating a rise time of a fixing roller.

FIG. 6 is a diagram showing a modification of the fixing roller of FIG.

FIG. 7 is a diagram illustrating a main part of a fixing roller according to a third embodiment of the invention.

FIG. 8 is a diagram showing a temperature distribution immediately after rising.

FIG. 9 is a diagram illustrating a shape of a nip portion of a conventional fixing roller.

FIG. 10 is an explanatory diagram illustrating a main configuration of an image forming apparatus including a fixing roller of the present invention.

FIG. 11 is a diagram illustrating a use state of the fixing roller of the present invention used in the image forming apparatus of FIG. 10;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Core metal 2 Heat insulation layer 3 Release layer base 3a Outer part 4 Release layer 10 Fixing roller

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2H033 AA02 AA30 BA05 BB04 BB12 BB19 BB23 BE06 3J103 AA02 AA15 AA24 AA33 AA41 AA51 BA16 BA17 BA19 BA22 BA24 FA01 FA15 FA18 FA20 GA02 GA57 GA58 GA60 GA66 HA01 HA03 HA04 HA05 HA19 HA32 HA33 HA36 HA37 HA43 HA51 HA54 HA60 3K058 AA02 BA18 DA04 DA26 GA06

Claims (7)

[Claims] 1. A toner image is transferred from a heating source outside a metal core by contacting a pressure roller with a predetermined pressure and inserting a transfer material on which a toner image is transferred between the pressure roller and the pressure roller. In a fixing roller that is heated and melted and fused onto a transfer material, the fixing roller has a core metal and a release layer on the core metal, and a fixing layer is provided between the core metal and the release layer. And a heat insulating layer is provided between the core metal and the heating source. 2. The fixing roller according to claim 1, wherein a release layer base is provided between the release layer and the heat insulating layer. 3. The fixing roller according to claim 2, wherein the core metal is fixed in a thrust direction at a step-shaped portion of the release layer substrate. 4. The fixing roller according to claim 2, wherein a thickness of the release layer substrate is smaller than a thickness of the core metal.
La. 5. The fixing roller according to claim 1, wherein the thickness of the heat insulating layer is greater at both ends than at the center. 6. The fixing roller according to claim 2, wherein the core metal and the release layer substrate have the same linear expansion coefficient. 7. A toner image is transferred from a heating source outside the cored bar by contacting the pressure roller with a predetermined pressure and inserting a transfer material on which the toner image is transferred between the pressure roller and the pressure roller. In a fixing device including a fixing roller that is heated and melted and fused onto a transfer material, the fixing roller includes a core metal and a release layer on the core metal, and the fixing roller is separated from the core metal. A fixing device including a fixing roller, wherein a heat insulating layer is provided between the mold layer and the core metal and the heating source.