JPH08234598A - Fixing device and image forming device - Google Patents

Abstract

PURPOSE: To provide a fixing device capable of preventing a high temp. offset from occurring while making an excellent fixing property compatible with it. CONSTITUTION: Electrodes 101 and 102 are applied over respective entire area of both sides of a base plate 13 consisting of piezoelectric ceramics such as PZT (zircon lead titanate), the surface of the electrode 101 is provided with an insulating layer 103, a resistive material 14 as a heating element in a linear state is applied thereon, and moreover a protective layer 51 composed of a glass material is provided thereon. Then, supplement of heat for the resistive material 14 is performed for instance, by applying high frequency AC voltage of 40kHz-150W between the electrodes 101 and 102 by a power source 30, and making the base plate 13 vibrate while self-generating the heat in such a manner. Moreover, the occurrence of off-setting is prevented by inserting the toner into fibers of a paper P by the high frequency vibration.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for heating and fixing a fixed image on a recording material, and more particularly to a fixing device having a heater and a sliding film, and an image forming apparatus equipped with this fixing device. .

[0002]

2. Description of the Related Art Conventionally, a heat roller fixing system has been widely used as a means for fixing a toner image on a recording paper. However, this heat roller fixing method has a problem that it takes a long warm-up time until the heat roller reaches a predetermined fixing temperature.

Therefore, the applicant of the present invention has filed Japanese Patent Laid-Open No. 63-3131
No. 82, JP-A No. 2-157878 and the like propose a fixing method using a heat resistant film.

This system (hereinafter referred to as SURF system)
Provides a resistance heating layer on a substrate made of a material with high thermal conductivity such as alumina, and applies heat to the unfixed image via the heat-resistant film while applying pressure with a pressure roller to transfer the toner onto the recording material. Unlike the heat roller method, it is melted and fixed, and only the pressure contact part of the heating element and the pressure roller is heated instead of the entire system, so there is an advantage that the time to reach the fixing temperature is fast and preheating is not required. .

Therefore, the power consumption is lower than that of the heat roller method, and it has been widely accepted in the market.

[0006]

However, since the heat capacity of the heating portion of this fixing method is smaller than that of the heat roller method, depending on the relationship with the amount of heat supplied by the heating element,
The temperature of the pressure contact portion may fluctuate greatly toward the low temperature side or the high temperature side due to paper passing or other external factors. For example, if it fluctuates to the low temperature side, fixing failure or low temperature offset may occur due to insufficient softening and melting of the toner, and if it fluctuates to the high temperature side, the toner completely melts and the cohesive force of the toner May decrease and high temperature offset may occur. Especially when the print speed is increased, it may be difficult to achieve both the fixability and the high temperature offset.

An object of the first invention according to the present application is to provide a fixing device in which prevention of high temperature offset and good fixing property are compatible with each other.

The second object of the present invention is to:
It is an object of the present invention to provide a fixing device capable of achieving the above object with a simple structure.

A third object of the present invention is to provide a fixing device which can achieve the above object at low cost by using materials widely used in the market. .

The object of the fourth invention of the present application is to:
An object of the present invention is to provide an image forming apparatus capable of forming a good image while achieving both prevention of high temperature offset and good fixing property.

A fifth object of the present invention is to provide an image forming apparatus capable of achieving the above object with a simple structure.

The object of the sixth invention of the present application is to:
An object of the present invention is to provide an image forming apparatus that can achieve the above object at low cost by using materials widely used in the market.

[0013]

According to the first invention of the present application, the above object has a heater, a film that slides on the heater, and a pressure member that forms a nip with the film. In the fixing device that fixes the image to be fixed by sandwiching and conveying the recording material supporting the image to be fixed between the film and the pressure member, the heater is provided with the linear heating element and the substrate of the piezoelectric vibrating element. It is achieved by providing a high frequency AC voltage to the substrate.

According to the second invention of the present application,
In the first aspect of the invention described above, the heater has a three-layer laminated structure including a linear heating element, a first substrate made of an insulator, and a second substrate made of a piezoelectric vibrating body. An alternating voltage is achieved by applying it to the second substrate.

Further, according to the third invention of the present application, the above object can be achieved by the first substrate in the second invention, which is an alumina substrate.

According to the fourth invention of the present application,
The purpose is to develop an image bearing member having a photosensitive layer, an exposing means for exposing the image bearing member according to image information, and an electrostatic latent image formed on the image bearing member by the exposure with a developer. A developing device, a transfer device for transferring a developer image to a recording material, and a fixing device in which a film is slid on a heater and a pressing member is brought into pressure contact with the heater via the film, are provided. In the image forming apparatus for sandwiching and conveying the formed recording material between the film and the pressure member of the fixing device to fix the developer image and form an image on the recording material, the heater of the fixing device is used. This is achieved by providing a linear heating element and a substrate of the piezoelectric vibrating body, and providing a means for applying a high frequency AC voltage to the substrate.

Further, according to a fifth invention of the present application, in the above-mentioned fourth invention, the heater of the fixing device has a linear heating element and a first substrate made of an insulating material. This is achieved by forming a three-layer laminated structure with a second substrate made of a piezoelectric vibrating body, and connecting the high frequency AC voltage applying means to the second substrate.

According to the sixth invention of the present application,
The above object is achieved in the above-mentioned fifth invention, in which the first substrate is an alumina substrate.

[0019]

According to the first invention of the present application, when a high frequency AC voltage is applied to a substrate formed of a piezoelectric vibrating body, the substrate vibrates at a high frequency to generate heat, and the heat is linear. It assists the heat generated from the heating element and improves the fixing property. Further, since the toner, which is the image to be fixed on the recording material, is pressed against the recording material by the high frequency vibration and woven into the fibers of the recording material, the occurrence of offset is suppressed.

According to the second invention of the present application,
In the first aspect of the invention, the heater has a three-layer laminated structure including a linear heating element, a first substrate made of an insulator, and a second substrate made of a piezoelectric vibrating body. Since it is applied to the second substrate, the high-frequency vibration of the second substrate and the heat generated by the high-frequency vibration are transferred to the linear heating element side via the first substrate, and the heat of the linear heating element is retained and the toner is removed. Press down.

Further, according to the third invention of the present application, in the above-mentioned second invention, since the first substrate is an alumina substrate, the insulation between the linear heating element and the substrate of the piezoelectric vibrating body is improved. Keep good.

According to the fourth invention of the present application,
A developer image is formed on a recording material by an image carrier, an exposure unit, a developing device, a transfer device, and the like, and the recording material on which the developer image is formed is conveyed to a fixing device. Since a high-frequency AC voltage is applied by a high-frequency AC voltage applying means to the substrate formed of the piezoelectric vibrating body provided on the substrate, the substrate vibrates at high frequency to generate heat, and the heat is linearly heated. By assisting the heat generated from the body, the developer image on the recording material can be fixed well. Further, since the developer image, which is the fixed image on the recording material, is pressed against the recording material by the high frequency vibration, the developer image is woven into the fibers of the recording material, so that the occurrence of offset is suppressed.

Further, according to a fifth invention of the present application, in the fourth invention, the heater is a linear heating element, a first substrate made of an insulator, and a second substrate made of a piezoelectric vibrating body. Since a high frequency AC voltage applying means is connected to the second substrate and a high frequency AC voltage is applied to the second substrate, a high frequency vibration of the second substrate,
The heat generated by the high frequency vibration is transferred to the linear heating element side via the first substrate, and the heat of the linear heating element is held and the toner is pressed.

According to the sixth invention of the present application,
In the fifth aspect of the invention, since the first substrate is an alumina substrate, good insulation is maintained between the linear heating element and the piezoelectric vibrating element substrate.

[0025]

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

(First Embodiment) FIG. 1 is a vertical sectional view showing an image forming apparatus according to a first embodiment of the present invention. FIG.
In FIG. 1, reference numeral 1 denotes an original placing table made of a transparent member such as glass, which reciprocates in the direction of arrow a to scan the original. A short-focus small-diameter image-forming element array 2 serving as an exposing unit is arranged immediately below the original document table 1, and the original image placed on the original document table 1 is illuminated by an illumination lamp 3, and the reflected light image is the above-mentioned. Slit exposure is performed on the photosensitive drum 4, which is an image carrier, by the array 2. The photosensitive drum 4 rotates in the direction of arrow b. Further, 5 is a charger, for example, uniformly charging the photosensitive drum 4 coated with a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer. On the photosensitive drum 4 uniformly charged by the charger 5, an electrostatic image is formed by image exposure by the array 2. This electrostatic image (electrostatic latent image) is visualized by a developing device 6 as a developing device using powder toner made of resin or the like that is softened and melted by heating. On the other hand, the recording paper P, which is a recording material stored in the cassette S, is a pair of conveyances that are rotated in pressure contact with each other in the vertical direction at a timing so as to be synchronized with the image on the feeding roller 7 and the photosensitive drum 4. By the roller 8, the photosensitive drum 4
Sent up. Then, the transfer discharger 9 which is a transfer device
Thus, the toner image formed on the photosensitive drum 4 is transferred onto the recording paper P. After that, the recording paper P separated from the photosensitive drum 4 by the known separation means is guided to the fixing device 11 by the conveyance guide 10, is heated and fixed, and is then discharged onto the tray 22. After the toner image is transferred, the residual toner on the photosensitive drum 4 is removed by the cleaner 2
Removed by 3.

FIG. 2 is an enlarged sectional view of the fixing device 11.
In the figure, reference numeral 12 is a heater having a low heat capacity fixed to the apparatus. For example, a resistance material 14 is formed on a substrate 13 made of a piezoelectric vibrating body having a thickness of 1.0 mm, a width of 10 mm and a longitudinal length of 240 mm. It is applied to a thickness of 0.0 mm, and electricity is applied from both ends in the longitudinal direction.

Energization is performed with a voltage value of 100 V and a cycle of 20 mse.
The pulse width is varied according to the desired temperature and the amount of energy released, which is controlled by the pulsed waveform voltage of c and is controlled by the temperature measuring element 15. The pulse width is approximately 0.5 to 5 msec.

As described above, the fixing film 16 is brought into contact with the heater 12 whose temperature and energy are controlled, and the fixing film 16 moves in the direction of the arrow in the drawing. As an example of the fixing film 16, a heat-resistant film having a thickness of 20 μm, for example, polyimide, polyetherimide, PES, PFA, and a release agent in which a conductive material is added to at least the image contact surface side of a fluororesin such as PTFE or PFA It is an endless film having a layer coated with 10 μm. Generally, the total thickness is less than 100 μm, more preferably less than 70 μm. This fixing film 16
Driven by the drive roller 17 and the driven roller 18 and the tension, it moves in the direction of the arrow without wrinkles.

Numeral 19 is a pressure roller having a rubber elastic layer such as silicone rubber having a good releasability, and presses the heater 12 through the fixing film 16 with a total pressure of 4 to 15 kg to rotate in pressure contact with the film 16.

The unfixed toner 20 on the recording paper P is guided to the fixing section by the entrance guide 21 and obtains a fixed image by the above heating.

FIG. 3 is an enlarged sectional view of the heating nip portion of the fixing device 11 shown in FIG. In the figure, 13 is a substrate made of piezoelectric ceramics such as PZT (lead zirconate titanate), and the electrodes 1 are formed on both sides in the pressure roller direction.
01 (pressure roller side, front side) and 102 (back side) are painted. An insulating layer 103 is provided on the surface of the electrode 101, and a resistance material 14 which is a linear heating element is applied on the insulating layer 103. Furthermore, a protective layer 51 made of a glass material is covered thereover.

The above piezoelectric ceramic substrate 13 and electrode 1
01, 102, insulating layer 103, resistance material 14, protective layer 5
1 is integrally formed, and as shown in FIG.
3 is attached by heat-resistant double-sided tape or heat-resistant adhesive. The heat insulator 53 is attached to the stay 52 that supports the heater portion. This stay 52
It is necessary to have a material and a structure that do not cause a large bending in the central portion even when pressure is applied by the pressure roller 19.

The piezoelectric ceramic substrate 13 may be made of barium titanate, zirconia oxide or the like, but PZT (lead zirconate titanate) used in this embodiment is moldable,
Most suitable in terms of cost. The electrodes 101 and 102 are made by printing a paste containing silver / Pt and glass as a main component and firing it, and have excellent electric conductivity. Insulating layer 10
Reference numeral 3 is made of a material having a small heat capacity such as alumina having a thickness of 0.1 to 2 mm, and is bonded to the front electrode 101 with an adhesive or the like. In this embodiment, as a heating resistance material on this,
A paste containing Ag / Pd (silver palladium) and glass as a main component is printed and fired, and further, a glass paste is printed thereon as a protective layer and fired.

A power source 30 serving as a means for applying a high frequency AC voltage between the electrodes 101 and 102, for example, 40
An alternating voltage of 150 W at a frequency of kHz is applied, whereby the substrate 13 vibrates and self-heats.
In the fixing device of the present invention, 1 kHz to 1 MHz, 50 to 4
A high frequency AC voltage of 00 W can be used.

In the experiment, by adopting this embodiment to the fixing device capable of fixing the linear heating element at a temperature of about 170 ° C., the temperature of the linear heating element capable of fixing is about 150 ° C., about 20 ° C. It became low. This is the piezoelectric ceramic substrate 1
When the high frequency AC voltage is applied, the element 3 vibrates in the direction of the arrow J and self-heats, thereby assisting the resistance material 14 which is a linear heating element.

Further, as shown in FIG. 4, it was observed that the toner particles were folded into the fibers of the paper by vibrating the piezoelectric ceramic substrate 13, which also suggests that the fixing property should be improved. . Further, since the toner has entered deep inside the fibers of the paper, the offset resistance against high temperature offset, electrostatic offset, etc. is also improved.

(Second Embodiment) FIG. 5 is an enlarged sectional view of a nip portion of a fixing device using the second embodiment. In this embodiment, the piezoelectric ceramic substrate 13 is arranged only on the upstream side of the resistance material 14 which is a linear heating element, and the substrate 103 of alumina or the like is used on the downstream side of the resistance material 14 so as not to vibrate.

With this configuration, when the recording paper P is separated from the fixing film 16, the temperature thereof is sufficiently lower than the fixing temperature, and the toner can be prevented from being offset to the fixing film 16.

Therefore, by using this embodiment, it is possible to supply a high-value-added fixing device in which the upstream and downstream sides of the heater substrate are functionally separated.

(Third Embodiment) FIG. 6 shows an enlarged sectional view of a heat generating portion of a fixing device using the third embodiment. In this embodiment, the piezoelectric ceramic substrate 13 is covered with a heat insulating member 106 made of liquid crystal polymer or the like to effectively send heat to the nip side.

According to this embodiment, the heat diffused to the surroundings by the high frequency vibration can be released from one place, and the electric power consumed for the vibration can be suppressed low.

[0043]

As described above, the first aspect of the present application
According to the invention, since the heater is provided with the linear heating element and the substrate formed of the piezoelectric vibrating body, and the high frequency AC voltage is applied to the substrate, the fixing property is improved and the offset is prevented. And a highly reliable fixing device can be supplied.

According to the second invention of the present application,
In the first aspect of the invention, the heater has a three-layer laminated structure including a linear heating element, a first substrate made of an insulator, and a second substrate made of a piezoelectric vibrating body. Since the voltage is applied to the second substrate, it is possible to provide a fixing device having the above effect with a simple structure.

Further, according to the third invention of the present application, in the above-mentioned second invention, the first substrate is an alumina substrate, so that a material widely used in the market is used and the cost is low. In the above, it is possible to provide a fixing device that achieves the above effects.

According to the fourth invention of the present application,
Since the heater of the fixing device is provided with the linear heating element and the substrate formed of the piezoelectric vibrating body and the means for applying the high frequency AC voltage is provided on the substrate, the fixing property is improved and the offset is prevented. An excellent image can be formed and an image forming apparatus with high reliability can be supplied.

Further, according to the fifth invention of the present application, in the above-mentioned fourth invention, the heater is a linear heating element, a first substrate made of an insulator, and a second substrate made of a piezoelectric vibrating body. Since the high-frequency AC voltage means is connected to the second substrate by forming a three-layer laminated structure with the substrate, it is possible to provide an image forming apparatus having the above effects with a simple configuration.

According to the sixth invention of the present application,
In the above fifth invention, since the first substrate is the alumina substrate, a material widely used in the market is used.
It is possible to provide an image forming apparatus that achieves the above effects at low cost.

[Brief description of drawings]

FIG. 1 is a schematic diagram of a copying machine according to a first embodiment of the present invention.

FIG. 2 is a schematic view of a fixing device according to the first exemplary embodiment of the present invention.

FIG. 3 is an enlarged cross-sectional view of a nip portion of the fixing device according to the first exemplary embodiment of the present invention.

FIG. 4 is a schematic diagram of post-fixing toner according to the first exemplary embodiment of the present invention.

FIG. 5 is an enlarged cross-sectional view of a nip portion of a fixing device according to a second exemplary embodiment of the present invention.

FIG. 6 is an enlarged cross-sectional view of a heater of a fixing device according to a third exemplary embodiment of the present invention.

[Explanation of symbols]

2 short-focus small-diameter image-forming element array (exposure means) 4 photosensitive drum (image carrier) 6 developing device (developing device) 9 transfer discharging device (transfer device) 12 heater 13 piezoelectric ceramic substrate (second composed of piezoelectric vibrating body)
Substrate 14 resistance material (linear heating element) 19 pressure roller (pressure member) 30 power supply (means for applying high-frequency AC voltage) 101, 102, 104, 105 electrode 103 insulating layer (first insulating material) Substrate) P Recording paper (Recording material)

Claims (6)

[Claims] 1. A heater, a film sliding on the heater, and a pressure member forming a nip with the film,
In a fixing device for fixing and fixing a fixed image by sandwiching and conveying a recording material supporting a fixed image between a film and a pressure member, the heater is provided with a linear heating element and a substrate of a piezoelectric vibrating element. A fixing device, characterized in that a high-frequency AC voltage is applied to the substrate. 2. The heater comprises a linear heating element, a first substrate made of an insulator, and a second substrate made of a piezoelectric vibrating body.
The fixing device according to claim 1, wherein the fixing device has a layered structure and a high-frequency alternating voltage is applied to the second substrate. 3. The fixing device according to claim 2, wherein the first substrate is an alumina substrate. 4. An image carrier having a photosensitive layer, exposure means for exposing the image carrier according to image information, and an electrostatic latent image formed on the image carrier by the exposure with a developer. And a fixing device in which a film is slid on a heater and a pressing member is brought into pressure contact with the heater via the film. In the image forming apparatus, the recording material on which the image is formed is nipped and conveyed between the film and the pressing member of the fixing device to fix the developer image and form an image on the recording material. An image forming apparatus comprising: a linear heating element and a substrate of a piezoelectric vibrating body, and means for applying a high frequency AC voltage to the substrate. 5. The heater of the fixing device has a three-layer laminated structure including a linear heating element, a first substrate made of an insulator, and a second substrate made of a piezoelectric vibrating body, and a high frequency AC voltage is applied. The means are connected to the second substrate.
The image forming apparatus according to item 1. 6. The image forming apparatus according to claim 5, wherein the first substrate is an alumina substrate.