JP2003280412A - Fixing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device by which paper is orderly stacked on an ejected paper tray by uniformizing the feeding property of the paper in a width direction by uniformizing pressure distribution in a nip and by obediently feeding the paper to a feeding path without causing extreme downward curling. <P>SOLUTION: In the fixing device constituted of a heater base plate on which a heating element is formed of the alloy of silver-palladium or the like on a ceramic base plate or the base plate of stainless steel or the like and also it is coated with a glass layer, a member (a base plate supporting member) to support the heater base plate, a member made of metal provided so as to reinforce the member and to apply pressure, film made of plastic to incorporate them and a rubber roller rotated and driven by abutting on the film, the curvature of a rubbing surface between the base plate supporting member and a film inner surface is set lower than that of a pressure roller on a downstream side in a pressure area. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a material to be heated which is adhered to a heating body via a film, and the material to be heated and the film are moved together so that the heat of the heating body is heated via a heat resistant film. The present invention relates to a film heating type fixing device.

[0002]

2. Description of the Related Art Conventionally, a heat roller type fixing device has been widely used. This is, for example, a copier,
It is used for fixing toner images in laser beam printers, etc., and the toner image on the recording material is melted and fixed by heating with the heat from the heating element maintained at a predetermined fixing temperature, and is fixed on the recording material. .

FIG. 10 shows an example of a film heating type heating device (image heating device). A cylindrical endless film 4-2 is used as a heat resistant film, and at least one of the perimeters of the film 4-2 is used. The unit is always tension-free (a state in which no tension is applied), and the film is rotated by the rotational driving force of the pressure roller 4-4 as a pressure rotating member. The film is rotated by the fixing roller before the paper enters the fixing nip, and the film is rotated by the rotation of the fixing roller.

When the paper is conveyed into the fixing nip, the paper and the film are rotated and the paper is conveyed by the rotation of the pressure roller. The film 4-2 is characterized in that the film thickness is 100 μm or less, and preferably 10 to 50 μm or so, which has high heat resistance, such as PTFE and P, in order to enhance heat transfer property, reduce heat capacity, and improve quick start property.
A single layer of FA or FEP or PTF on the outer peripheral surface of polyimide, polyamide-imide, PEEK, PES, PPS, etc.
A composite layer film in which E, PFA, FEP and the like are mixed and coated can be used. 4-3 is a heating element 4-1
Is a holder for heat-insulating and supporting, and 4-3 ′ is an instruction stay (iron stay) made of metal such as iron for supporting the film under pressure.

The heating element 4-1 is a horizontally long linear heating element having a low heat capacity, and is formed on a heater substrate 4-5, which is a ceramic substrate such as alumina (Al 2 O 3), as a heating resistor 4-6, for example, Ag. / Pd (silver-palladium) or other electric resistance material having a thickness of 10 to 30 μm and a width of 0.8 to 3 mm is applied and baked by screen printing or the like, and glass or an overcoat layer (protective layer) 4-7 is formed thereon. It is coated with fluororesin. This heating body 4-1 is a groove 4-3 provided along the longitudinal direction on the outer lower surface of a holder 4-3 for heat-insulating and supporting the heating body.
It is fitted and fixed to a by being fixedly supported.

The heating element 4-1 is an energization heating resistor 4-6.
By heating the energization heat generating resistor over the entire length of the energization heat source, the temperature is rapidly raised, and the temperature rise is detected by the temperature detecting element 4-8 and fed back to a control system (not shown) to heat the image. The energization of the heating resistor 4-6 is controlled so that the temperature of the temperature detecting element 4-8 is maintained at a predetermined set temperature.

4-2 is a stay 4-3 including the heating element 4-1.
It is a cylindrical heat resistant film that is fitted onto the
It is loosely fitted to the stay 4-3 including 1 with a margin in the circumferential length. Reference numeral 4-9 is a flange member that receives the end portion of the film as a means for restricting the shift of the film. The reference numeral 4-10 forms a pressure contact nip portion (fixing nip portion) N with the film 4-2 sandwiched between it and the heating body 4-1, and also serves as a pressure rotating body for rotationally driving the film 4-2. The pressure roller is composed of a metal shaft 4-10a and a heat-resistant rubber layer 4-10b having a good releasability such as silicon rubber. The film 4-2 is pressed with a predetermined pressing force by bearing means and urging means (not shown). It is arranged so as to be sandwiched and pressed against the surface of the heating element 4-1. Then, the driving means transmits the rotational driving force through a power transmission system (not shown), and the rotational driving is performed in the counterclockwise direction indicated by the arrow.

A rotational force acts on the film 4-2 due to the frictional force between the roller 4-10 and the outer surface of the film 4-2 due to the rotational driving of the pressure roller 4-10 (the recording material P is pressed to the nip portion N). When it is introduced into the film 4-2, the rotational force indirectly acts on the film 4-2 via the material P to be heated,
Is pressed and slid on the surface of the heating element 4-1, and is rotationally driven in the clockwise direction a indicated by an arrow. The stay 4-9, which also serves as a film inner surface guide member, facilitates rotation of the film 4-2.

As described above, the front end of the recording material P supporting the unfixed image (toner image) T to be image-fixed on the basis of the press of the copy button or the print command signal of the copying machine such as the copying machine, Based on the signal detected by a sensor (not shown) arranged on the front side of the device, the pressure roller 4
The rotation drive of -10 is started, and the temperature rise of the heating body 4-1 is started.

When the rotation peripheral speed of the film 4-2 is stabilized by the rotation of the heating roller 4-10 and the temperature of the heating body 4-1 rises to a predetermined value, the film 4-2 in the fixing nip portion N is pressed against the film 4-2. The recording material P to be image-fixed as a material to be heated is introduced between the roller 4-10 and the fixing nip portion N is conveyed together with the film 4-2 so that the heat of the heating body 4-1 is generated. Is applied to the recording material P via the film 4-2, and the unfixed developer image T is heated and fixed on the surface of the recording material P. The recording material P that has passed through the fixing nip portion N is separated from the surface of the film 4-2 and conveyed. The area of the nip N includes the pressure roller 4-10 and the substrate 4.
It is a region between -1 where pressure and temperature are applied.

Further, the heating element 4-1 has conductive patterns 5-15 and 5-16 of the heating resistor 5-12 and a heating resistor 5 as shown by the heating element front surface and the heating element back surface in FIG. -12
Power feeding electrode pattern 5-13-5-14, a temperature detecting element 5-24 such as a thermistor, and a conductive pattern 5-of this element.
22, 5-23 and conductive patterns 5-22, 5 through through holes 5-20, 5-21 penetrating from the back surface of the heating element.
Power supply electrode patterns 5-18 and 5-19 of the temperature detecting element 5-24, which energize -23, are arranged.

As shown in FIG. 12, a connector 5-31 for fixing and supporting the heating element on the stay is attached to the feeding pattern 5-13-5-14 of the heating element, and the connector 5-31 is attached.
By the heating spring 5-32 as an internal electric contact, the heating resistor 5-12 is connected to the power source 5- through the power feeding wire 5-33.
34 and a triac 5-35, etc. are connected.

Further, the feeding electrode pattern 5-18 of the heating element,
A connector 5-36 for fixing and supporting the heating element to the stay is attached to the stay 5-19, and a pressure spring 5-37 as an electrical contact in the connector is used to detect a temperature via a power supply wire 5-38. The element 5-24 is connected to the A / D converter 5-39 of the control system. As the temperature information of the heating element, the thermistor voltage of the temperature detecting element 5-24 provided in the paper passing area of the recording material P is input to the A / D converter 5-39 and taken into the CPU 5-40 as digital data.

The CPU 5-40 controls the triac 5-35 to control the temperature of the heating element to a predetermined constant temperature based on the input digital data. As a control method,
The method of controlling the pressurizing voltage or current of the heating resistor 5-12 or controlling the energization time is adopted. Methods for controlling the energization time include zero-cross wave number control for controlling whether or not to energize for each half-wave of the power supply waveform, phase control for controlling a phase angle for energizing for each half-wave of the power supply waveform, and the like.

On the other hand, in the fixing film, as shown in FIG. 10, the conductive primer is -600 V for improving the image.
Bias is applied and high voltage is applied to leaf spring contact 4-1.
1 to the conductive primer 4-13 of the film 4-2 through the conductive rubber 4-12. The film consists of a polyimide film, a conductive primer layer, and PTFE and PFA or FEP on it.
A composite layer film having a total thickness of 60 μm was used, which was coated with a fluororesin consisting of a mixture of the above, and the mixture of PFA or FEP with respect to this PTFE was 10 to 30% by weight or more.

On the other hand, FIG. 1 shows a constitutional view of the main body, in which a photosensitive roller 1-2 is charged to approximately -600 V by a charging roller 1-6, and a laser scanner 1-11 is based on image information.
The laser L is emitted from the above to form a latent image. Then, the toner adheres to the portion where the latent image is formed by the developing roller.

On the other hand, the paper P is conveyed from the cassette by the pickup roller 1-10, is conveyed to the transfer position Tr through the conveying roller 1-1, and is applied to the transfer roller 1-3 (around 1 kV to 5 kV). So the photosensitive drum 1-
The image formed on 2 is transferred to paper and the fixing device 1-
5, the sheet is discharged to the discharge roller 1 through the fixing nip T portion.
The toner remaining after being conveyed by 6 for image output and being transferred on the photosensitive drum 1-2 at the same time is cleaned by the cleaning unit 1-7 to prepare for the next image formation again.

FIG. 4 shows a conventional structure in which the paper is conveyed out of the fixing nip after a series of printing operations.

In the downstream of the nip, the paper is conveyed below the nip horizontal line to the outside of the nip, or in Japanese Patent Laid-Open No. 10-
As shown in Japanese Patent No. 312124, it is configured to be gently conveyed upward. The film is opened upward outside the area where the pressure roller and the film are pressed.

However, in such a structure, the paper is conveyed so as to curl downward from the fixing nip so as to be wrapped around the pressure roller. As the printing speed increases and the printing speed increases, the fixing temperature and the pressing force increase, and the temperature and the pressure are applied to the paper in the fixing nip in a shorter time, and the stress on the paper further increases. As a result, if you try to forcibly correct the waviness and wrinkles of the paper in the transport system after fixing, more stress will be generated inside the paper and wrinkles will occur, and eventually the paper tray discharged will It will be an unsightly situation where it will be loaded cluttered.

[0021]

SUMMARY OF THE INVENTION In the above conventional example,
When a print command is issued to the main body of the machine and the fixing device is pre-multi-rotated and the film and the pressure roller rotate in the directions of the arrows in FIG. 10 to reach a certain temperature or higher, as described in the conventional example. Starting from latent image formation, development is performed according to an electrophotographic process, toner is transferred to paper, and the toner is conveyed to a fixing device. Before the paper enters the fixing nip, the film is rotated by the fixing roller, and the film is rotated by the rotation of the fixing roller.

When the paper is transported into the fixing nip, the rotation of the pressure roller rotates the film and the transport of the paper and the film. In the nip, the temperature on the paper becomes around 100 ° C, water or water vapor contained in the paper is generated, the paper curls so that it wraps around the pressure roller, and it is transported after fixing and is conveyed to the printer's discharge surface. Even if they are loaded, they are not loaded in an orderly manner, and when the number of sheets is further increased, the paper drops from the paper ejection guide, which makes the document arrangement complicated.

The present invention has been made in view of the above problems, and an object thereof is to make the pressure distribution in the nip uniform so as to make the transportability of the paper uniform in the width direction and curl the paper extremely downward. It is an object of the present invention to provide a fixing device that can be directly conveyed to a conveyance path and can be stacked on a discharge tray in an orderly manner without performing the above.

[0024]

In order to achieve the above object, the present invention provides a heating element formed of an alloy such as silver-palladium on a substrate such as a ceramic substrate or a stainless steel plate, and a glass layer is further formed thereon. Coated heater substrate, member for supporting the heater substrate (substrate supporting member), metal member provided to reinforce the member and apply pressure, plastic film containing these, and the film In a fixing device composed of a rubber roller that abuts against and can be driven to rotate, the curvature of the rubbing surface of the substrate support member and the inner surface of the film is set to be smaller than the curvature of the pressure roller in the downstream side in the pressure area. Is characterized by.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the accompanying drawings.

2 to 7 show an embodiment of the present invention.
In the area where the paper is conveyed from the upstream side into the nip and the heat-resistant plastic stay and the pressure roller are in contact with each other via the film at the downstream side as illustrated, the radius r of curvature of the plastic stay is smaller than the radius R of the pressure roller. When there is no intervening paper, the structure is raised above the horizontal line formed by the nip.

<First Embodiment> In the present invention, for example, as shown in FIG. 2, the radius rx at which the plastic stay 2-3 comes into contact with the film 2-2 on the downstream side of the nip is eight.
mm, and the radius R of the pressure roller 2-10b is 10 mm
Is.

The pressure roller 2-10b has a diameter of 20 mmφ,
The core metal 2-10a is a round bar of aluminum 6 mmφ, and a silicon rubber layer and a surface layer 2-4 coated with a fluororesin or a core covered with a fluorine tube is used. The outer diameter of the film 2-2 is 24 mmφ, which is an endless film of polyimide resin coated with fluororesin. The substrate 2-1 is made of alumina and has a thickness of 1.0 mm and a width of 6 mm.

The cross-sectional width of the pressure area of the nip is 8 mm, the length in the longitudinal direction is 240 mm, and the pressing force is 15 kgf. Further, the paper conveyance speed is 86 mm / in this embodiment.
sec, the fixing temperature control temperature is 195 ° C.

FIG. 3 shows the relationship between the pressure roller and the film in the downstream region of the nip portion. The surface layer of the pressure roller is raised above the horizontal line in the nip, and has the action of discharging the paper above the horizontal.

In FIG. 1, which shows the constitution of the main body by conveying the paper in the upward direction, the paper is loaded on the paper discharge tray 1-12 in an orderly manner without going against the shape of the conveying path.

Further, the direction of curl in which the paper is discharged out of the nip in this configuration will be described with reference to FIG.

The radius of the pressure roller is R, and the radius of the film conveyed downstream of the nip along the plastic stay is r.
Immediately after being discharged, the paper is placed on a horizontal plate as shown in FIG. 6, and the curl amount L of the front end of the paper at that time is measured. In the above condition, after passing through the nip, the upward curl is expressed as + L, and the downward curl is expressed as -L. Curl down is measured on a horizontal plate with the paper turned upside down.

In the combination of the main body structure and the fixing device as shown in FIGS. 1 and 2, Rx = 3, 5, 8, for R = 10 mm.
10, 12, 15, 20 mm, that is, rx / R = 0.
3, 0.5, 0.8, 1.0, 1.2, 1.5, 2.0
Fig. 7 shows a summary of the above. In the figure, x indicates that the discharged paper is disturbed due to the curl of the paper and the sheets are not loaded in order, and ◯ indicates the state in which they are loaded in order. re / R = 1.
At 0, the sheet is ejected in both the upper and lower curved surface tangential directions immediately after passing through the nip, but the value of L becomes slightly negative due to the influence of gravity immediately after the ejection of the sheet. rx / R = 0.5, that is, R =
When 10 mm and rx = 5 mm, L = 0, and the stackability is further improved.

In the configuration of a so-called face-down paper path in which the printing surface faces downward after stacking after passing through the nip as shown in FIG. 1, the stackability is further improved when the L value is slightly positive.

<Embodiment 2> In the present invention, in the relationship between the pressure roller diameter in the pressure area and the pressure roller diameter in the downstream area, the radius of curvature of the pressure roller is R and the pressure on the downstream side in the paper conveying direction is It has been found that when the radius of curvature of the substrate supporting member that rubs against the inner surface of the film in the region is r, the effect is more remarkable if it is configured such that r ≦ (1/2) * R. Has a radius of curvature of R = 10 mm, and the radius of curvature of the substrate supporting member that rubs against the inner surface of the film is r = 3.
In the case of mm, even if the paper conveying speed, the pressing force, and the temperature were further increased, the papers were properly loaded on the discharge tray.

In the present embodiment, the paper conveyance speed is 100 mm / sec, the pressure is 18 kgf, and the fixing temperature control temperature is 210 ° C.

<Embodiment 3> Since curling of the paper after fixing is particularly noticeable at both ends, r ≦ (1/2) * R at both ends of the fixing nip in the structure described in Embodiment 2. Configure to be satisfied.

FIG. 8 shows the relationship of A4 size width dimensions.
An area of 1/3 or more of the paper width size L is configured so that the above expression is satisfied at both ends of the fixing nip. That is, in the region of 1/3 or more of both ends with respect to the width L of the paper, the nipping of the paper in the nip (the surface layer of the pressure roller is raised above the horizontal line in the nip, and the paper is discharged above the horizontal). The function that works like) is generated.

Since the width of the paper A4 is 210 mm,
/ 3, that is, the squeeze is applied to the paper up to 70 mm from both ends of the paper. 85mm from both left and right sides of the heater
The area is defined as (1), and the above expression is satisfied up to an area corresponding to 1/3 of the A4 size width.

Similarly, FIG. 9 shows the dimensional relationship of the A3 size width. In the A3 size width, L = 297 mm, and in order to configure the above formula up to a region corresponding to 1/3 of the A4 size width, the above formula is satisfied within a region of 114 mm from both ends of the heater. By doing so, the nipping of the paper on the paper occurs and the curling of the paper can be prevented.

Further, other effects of paper transportation will be described.

In the constitution of the fixing device according to the present invention, pressure is applied at both ends, and in the case of A4 width, the total load is 18 kg. Since the pressure distribution in the nip is slightly higher in the region of both ends ⅓ than in the center, in the conventional configuration as shown in FIG. 4, that is, the configuration in which the paper is discharged downward after passing through the nip, The width is wide at both ends, and the balance of paper transportability is lost in the central region and both end regions. As a result, the paper is likely to be wrinkled.

As in the present invention, the surface of the pressure roller is bulged above the horizontal line in the nip at both ends, and the paper is discharged above the horizontal line. Is reduced, and as a result, the pressure distribution in the nip becomes more uniform in the center and both end regions, and the transportability of the paper becomes uniform.

The dimensions of each component are the same as those of the second embodiment, the radius of curvature R of the pressure roller is 10 mm, the radius of curvature r of the substrate supporting member that rubs against the inner surface of the film is 3 mm, and the paper transport speed is 100 mm / sec. , Pressing force = 18 kgf,
Fixing temperature control temperature = 210 ° C. Since both ends of the paper are predominantly curled, the paper is neatly stacked on the discharge tray with this configuration.

[0046]

As is apparent from the above description, according to the present invention, the paper is directed upward in the nip of the pressure area, that is, the curvature of the rubbing surface between the substrate supporting member and the inner surface of the film. Is configured to be smaller than the curvature of the pressure roller on the downstream side in the pressure area, the pressure distribution in the nip is made uniform, and the transportability of the paper becomes uniform in the width direction. It is transported straight to the transport path without curl and is loaded on the paper discharge tray in an orderly manner.

[Brief description of drawings]

FIG. 1 is a configuration diagram of an entire main body.

FIG. 2 is an overall view of a fixing unit of the present invention.

FIG. 3 is an explanatory diagram of the present invention.

FIG. 4 is an explanatory diagram of the present invention.

FIG. 5 is an explanatory diagram of a conventional configuration.

FIG. 6 is an explanatory diagram of the present invention.

FIG. 7 is an explanatory diagram of the present invention.

FIG. 8 is an explanatory diagram of the present invention.

FIG. 9 is an explanatory diagram of the third embodiment of the present invention.

FIG. 10 is an explanatory view of a conventional example and is a cross-sectional view of the entire fixing unit.

FIG. 11 is a perspective view showing the entire fixing unit.

FIG. 12 is an explanatory diagram of a substrate.

[Explanation of symbols]

1-1 Conveyor roller 1-2 Photosensitive drum 1-3 Transfer roller 1-4 Development sleeve 1-5 Fixing unit 1-12 Paper ejection tray 2-1 Substrate 2-2 film 2-3 plastic stay 2-4 Pressure roller surface

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Tatsufumi Mizuno             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation (72) Inventor Ryo Ono             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation F term (reference) 2H033 AA15 BA25 BA26 BB29 BB30                       BB33 BE03                 3K058 AA61 BA18 DA21 GA03 GA06

Claims (3)

[Claims] 1. A heater substrate in which a heating element is formed of an alloy of silver-palladium or the like on a ceramic substrate or a substrate such as a stainless steel plate, and a glass layer is further coated thereon, and a member for supporting the heater substrate ( Substrate supporting member), a metal member provided to reinforce the member and apply a pressure, a plastic film containing these members, and a rubber roller which is in contact with the film and can be rotationally driven. In the fixing device, the curvature of the rubbing surface between the substrate supporting member and the inner surface of the film is set to be smaller than the curvature of the pressure roller on the downstream side in the pressure region. 2. A part of the surface of the pressure roller is located above the horizontal line of the nip obtained by pressing the film and the pressure roller immediately after the downstream of the nip. The fixing device according to item 1. 3. When the radius of curvature of the pressure roller is R and the curvature of the substrate support member that rubs against the inner surface of the film in the pressure region on the downstream side in the paper transport direction is r, r ≦ (1/2) * R is a fixing device.