JPS61130973A - Fixing device - Google Patents

Abstract

PURPOSE:To shorten warming-up time with a light weight and small size and to improve fixing performance by pressing an upper roll having a heat source and thin film belt to each other at >=5mm nip width and bringing a surface to be fixed to the upper roll side. CONSTITUTION:A heater 8 is provided in a hollow metallic roll 6 and the upper roller 2 coated with a release layer 7 on the outside periphery is formed of iron or aluminum with a small wall thickness, light weight and small heat capacity. The nip width W at which the conveying belt 5 consisting of the thin film extended between rollers 3 and 4 and the upper roller 2 contact with each other is set at >=5mm. The entire part is therefore made light weight, small size and inexpensive and the warming-up time is shortened. The excellent fixing performance with less disturbance of image quality is obtd. with low electric power and low pressure.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a fixing device, and more particularly to a fixing device for heating and fixing a transfer paper having a powder toner image in an electrophotographic recording device, a printer, a facsimile, etc. It is something.

(Prior Art) Generally, a fixing device used in electrophotographic recording devices, printers, facsimiles, etc., for heating and fixing transfer paper on which a powder toner image is formed, uses a pair of upper and lower heat rolls. The configured heat roll fixing device and the
Publication No. 18634 and U.S. Patent No. 3,637,976
The one shown in the publication is proposed.

The hot roll fixing device is composed of an upper roll having a release layer formed by applying Teflon coating on the surface of the metal roll, and a lower roll having a core metal roll or a metal roll applied with a soric rubber layer.

The waiting time of such a thermal roll fixing device, that is, the warming-up time, is determined by the time required for the heat source installed inside the roll to reach a temperature at which the roll surface temperature or between the rolls can be fixed. In order to shorten the diameter of both rolls,
Alternatively, it is necessary to reduce the heat capacity by thinning the wall thickness of both rolls, but if both rolls are made small in diameter (small), the pressure range between the upper and lower rolls, that is, the pressure range between the upper and lower rolls becomes narrower, and therefore the temperature of both rolls becomes smaller. Unless the pressure is increased or the pressure (single pressure) between both rolls is increased, the fixing ability deteriorates and the fixing ability cannot be guaranteed.

In this case, increasing the temperature of the rolls requires increasing the power of the heat source, which has the disadvantage of making the whole thing more expensive. The wall thickness of the roll must be made thicker so that it can withstand greater strength, but this also increases the power of the heat source (otherwise it has the disadvantage of lengthening the warming-up time; Attempts to shorten the warming-up time by increasing the power, adjusting the set temperature, or adjusting the roll thickness have had the disadvantage of having limitations.

Furthermore, in order to increase the nip width, there is a method of lowering the hardness of the silicone rubber constituting the lower roll, but lowering the hardness still has the disadvantage that there is a limit in terms of durability.

In addition, in the case of what is shown in Utility Model Publication No. 18634, PI! , 'fl is installed on the upper surface of the hollow lower roll, and the upper belt that comes into contact with the toner image is coated with a highly non-adhesive fluororesin. Although it has a structure that drives at the same speed, the upper belt made of tetrafluoroethylene resin, Mylar, and glass fiber has insufficient heat resistance and durability, and the With heating using a heat source, the toner image is located on the top surface of the transfer paper (photosensitive paper in the above-mentioned practical application), so heating is performed from the transfer paper side, which has the disadvantage of slowing down the fixing speed. There is.

Furthermore, in what is shown in U.S. Pat. No. 3,637,976, the structure of an upper roll and a lower belt is
The upper roll has a three-layer structure of quartz glass, a conductive layer (NES^), and a non-adhesive layer, and the lower belt is an endless belt with low thermal conductivity, and a heat source installed inside the upper roll. The radiant heat is used to heat the toner image on the upper surface of the transfer paper 9, and the transfer paper is heated only when it passes between the upper roll and the lower belt.

However, with this structure, the upper roll has a three-layer structure, which is complicated, and the quartz glass part is easily damaged.Furthermore, since it uses radiant heat, it is subject to various limitations. It had the disadvantage that the whole thing was expensive.

(Objective of the Invention) This invention eliminates the drawbacks of the conventional products as described above, makes the entire device smaller and lighter, and is less expensive. Furthermore, the warm-up time is shortened. It is an object of the present invention to provide a fixing device that can perform high fixing with low power and pressure, has excellent fixing performance, and has little disturbance in image quality due to fixing.

[Structure of the invention]

This invention has an internal heat source and an upper roll consisting of a metal roll and a surface release layer, and an am* belt made of a heat-resistant film located below the upper roll, with a nip width of 5-
The rollers are brought into contact with each other as described above, and the surface to be fixed is on the upper roll side.

If the nip width is less than 5 mm, sufficient fixing performance cannot be obtained when the upper roll surface temperature is at an appropriate temperature. Or the linear speed of the transfer paper had to be slowed down.

[Example of invention] Embodiments of the invention shown in the drawings will be described below.

FIG. 1 shows a fixing device according to the present invention, and this fixing device includes a lower belt I, an upper roll 2 that comes into contact with approximately the center of the upper surface of the lower belt L, and 1 is composed of a pair of rollers 3.4 arranged at a predetermined interval in the horizontal direction, and a conveyor belt 5 made of a heat-resistant film stretched between the pair of rollers 3.4, and The upper roll 2 has a surface mold release layer 7 formed on the outside of a hollow metal roll 6, and a heater 8 as a heat source is provided inside the hollow.

Note that lO is a transfer paper having toner 9 on its upper surface.

The upper roll 2 is made of iron or aluminum, but is preferably made of iron in order to be thin, that is, sufficiently durable, lightweight, and have a small heat capacity, and its wall thickness hum is 50 μm. ~1000μm
It is preferably in the range of 70 μm to 600 μm.

The surface release layer is made of a fluoropolymer, such as tetrafluoroethylene (PTFE) (Teflon, manufactured by DuPont),
Made of 3-fluoride heptaethylene (FEP), PFA, etc., several tens of microns thick.
m to several hundred μm is preferable, and the roll diameter DUR is l
O-tsuru to 50fl, preferably 20-tsuru to 45-tsuru is good.

The thickness and diameter of the upper roll are selected within the above ranges in order to manufacture a fixing device that uses low power, is small, lightweight, inexpensive, and has high durability. In particular, the above preferable range was required in order to keep the power of the heat source as low as possible.

On the other hand, the conveyor belt 5 of the lower belt l that comes into contact with the upper roll 2 as described above is made of polyimide (Kapton (manufactured by DuPont), TI Receipt Toshi), nylon film, etc., and has a thickness of hl, .

is 10 μm to 20011 m.

The thickness of the lower belt was selected based on the strength of the belt, ease of assembly and installation, ease of use of materials, cost, etc.

Then, if necessary, a release layer is formed on the surface, and this release layer is made of a fluoropolymer, such as Teflon, or a silicone rubber layer with a thickness of 20μ, for example.
For m1 silicone rubber, a thickness of 50 μm or 100 μm is formed.

and a pair of rollers 3.4 that drive the conveyor belt 5.
Even if both rollers 3.4 are driven,
Even if either one of them is driven, the conveyor belt 5 may move in a direction perpendicular to the conveyance direction and the horizontal direction while the conveyor belt 5 is still being driven, that is, while the conveyor belt 5 is moving. A mechanism is provided to prevent this.

Note that the width when the lower belt l and the upper roll 2 are in contact with each other as described above, that is, the width WH2 is WNP≧
5 cranes, and the fixing pressure when the transfer paper is positioned between the lower belt 1 and the upper roll 2 is 10 to 20 g/-
The temperature of the heater 8 is approximately 300W to 700W, and the temperature of the heater 8 is 1III when a fixing device is installed.For example, when the copy button of an electrophotographic copying device is pressed, the heater 8 is turned on in conjunction with , it turns OFF when the paper ejection is completed, but ON-OFF control may be performed by a temperature sensor etc. as necessary.Furthermore, the lower belt 1 and the upper roll 2 are driven as described above. Both rollers 3.4 of the lower belt 1 may be driven individually or only one of them may be driven, and the upper roll 2 may or may not be driven. However, the surface speed of the upper roll 2 and the top surface speed of the conveyor belt 5 are completely different.

Next, an experimental example using the fixing device configured as described above will be described below.

[Experiment example-■]

In this experimental example, a fixing device as shown in FIG. 2 was used.

That is, this fixing device has an upper roll cleaner or oil application device 20 that contacts the upper roll 2 as necessary, a belt cleaner 21 is provided on the conveyor belt 5 as necessary, and a heater 8 is provided with a belt cleaner 21 as necessary. A heater power supply control device 22 is connected, and the same members as those in the previous embodiment are given the same numbers and the description thereof will be omitted.

The upper roll 2 is made of iron, has a diameter (Du++) of 35 mm, and a wall thickness (h□) of 0.5 mm. 5 cranes,
The surface release layer was a Teflon layer with a thickness of 20 IIm, while the conveyor belt 5 was made of Kapton with a thickness of 50 μm.
The surface layer was made of silicone rubber and had a thickness of 100 μm.

In addition, the fixing pressure acting on the transfer paper is 10 g/d, the width of 27 sheets (W work,) is 9 m, and the linear speed of the transfer paper is 70 B/SeC.
The power of the heater 8 is 400W, the driving method is to drive only the roller 4 of the lower belt, and the upper roll 2 is rotated by the conveyor belt 5, and the temperature control is ON only when the transfer paper passes, that is, when copying When the button was turned on, it was turned on, and w4m was turned off when paper ejection was completed.

When fixing a transfer paper having a toner image on the upper surface under the above conditions, the thickness of the conveyor belt 5 hIL? is 5
Good fixing performance could be obtained in both cases of 0 am and 20 μm, and good images with little disturbance in image quality could be obtained.

[Experimental Example-■] This experimental example was also carried out using a fixing device as shown in FIG. 2, and each condition was different from that of the above-mentioned Experimental Example-■.

That is, the material of the upper roll 2 is made of iron, and
Diameter (DIll) is 40ts, wall thickness (h□) is 0.6
m, the surface release layer was a Teflon layer with a thickness of 20 μm, while the conveyor belt 5 was made of a TI sheet with a thickness of 75 μm;
The surface layer was a Teflon layer with a thickness of 20 μm.

In addition, the fixing pressure acting on the transfer paper is 20 g/aj, the nip width (W□) is 1-2 cranes, and the linear speed of the transfer paper is 140 W.
/sec, the power of the heater 8 was 600 W, the driving method was to drive the roller 4 of the lower belt 1 and the upper roll 2 separately, and the temperature was controlled by a sensor.

When fixing a transfer paper with a toner image on the upper surface under the above conditions, the thickness of the conveyor belt is 75 μm and 50 μm.
Good fixing performance could be obtained in any case of μm, and good images with little disturbance in image quality could be obtained.

〔Effect of the invention〕
I By having the structure as described above, this invention is extremely small and lightweight, and can be manufactured at low cost.Moreover, the warming amplifier time can be shortened, and fixing can be performed with low pressure and low power. It has good performance and also has excellent effects such as less disturbance of the image due to fixing.

[Brief explanation of drawings]

The drawings show a fixing device according to the invention, FIG. 1 is a schematic diagram, and FIG. 2 is a diagram showing the fixing device according to the invention on which experiments were conducted. 1... Lower belt 2... Upper roll 3.4... q-ra 5... Conveyor belt 6... Metal roll 7. ... i. Surface female layer 8 ... Heater 9 ... Toner = 10 ... Transfer paper 20 ... Upper roll cleaner or oil coating II
IW. 21...Belt cleaner 22...Heater power supply control vtIW□...
・Nip width

Claims (2)

[Claims] (1) An upper roll having an internal heat source and consisting of a metal roll and a surface release layer is brought into contact with a thin film belt made of a heat-resistant film located below the upper roll so that the nip width is 5 mm or more. A fixing device characterized in that the fixing device is configured such that the surface to be fixed is on the upper roll side. (2) The thickness of the metal roll is h_U_R, and the diameter is D_
When U_R is defined as h_R_L_T and the thickness of the thin film belt made of the heat-resistant film is h_R_L_T, 50 μm≦h_U.
_R≦1000μm, 10mm≦D_U_R≦50mm
The fixing device according to claim 1, wherein 10 μm≦h_U_L_T≦200 μm.