JPH02162382A - Fusing device - Google Patents

Abstract

PURPOSE:To prevent the surface of a fixed toner image from becoming glossy and to eliminate a decrease in picture quality by roughening the surface of a fixation film on the side where the film contacts with a toner image. CONSTITUTION:The fixation film 24 is formed by laminating a peeling layer 24b of fluororesin, silicone resin, etc., on a heat resistant layer 24a made of a high heat resistant resin film, metal, etc., as a base layer and roughening the external surface of the layer 24b into a roughened surfaces 24c. The surface 24c is formed by working the layer 24b with a sand blast, mixing a filler with the peeling layer material, embossment, etc. Consequently, the decrease in picture quality due to glossiness is eliminated. The fixation film is roughened within a range of 0.3 - 10mum ten-point means roughness.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an image forming apparatus such as a copying machine, a laser beam printer, a facsimile machine, a microfilm reader printer, an image display device, and a recording machine.

More specifically, recording materials (electrofax sheets, electrostatic recording sheets, transfer material sheets, An unfixed toner image corresponding to target image information is formed and carried on the surface of printing paper by a direct method or an indirect (transfer) method, and the unfixed toner image is transferred to a recording material that carries the image. The present invention relates to an image forming apparatus that performs heat-fixing processing to form a permanently fixed image on a surface.

(Prior Art) Conventionally, a fixing device used in this type of device uses a heating roller maintained at a predetermined temperature and a pressure roller having an elastic layer and in pressure contact with the heating roller. A roller fixing method is often used in which a recording material on which a toner image has been formed is heated while being nipped and conveyed.

Also known is an open belt fixing system as disclosed in US Pat. No. 3,578,797. This is a state in which the toner image is brought into contact with a heating web and heated to its melting point and melted; after melting, the toner is cooled to a relatively high viscosity; and ■ the tendency of the toner to stick is weakened. In this method, the adhesive is fixed without causing offset by peeling it off from the heating web.

(Problems to be Solved by the Invention) However, the conventional hot roll fixing method and belt fixing method as described above have the following problems.

Heat roll fixing method ■It takes a considerable amount of time to reach a predetermined temperature, during which time image formation is prohibited.

That is, there is a so-called wait time.

■Because it requires heat capacity, a large amount of electric power is required.

■A special heat-resistant bearing is required because the roller temperature is high for rotating rollers.

■The rollers are in direct contact with the hands, which may be dangerous or require protective materials.

■Due to the roller's constant temperature and curvature, the recording material wraps around the roller and the recording material jams. This makes it easy to see the trouble.

Belt fixing method This method also has the same problems as the above-mentioned heat roller fixing method, such as wait time and large power consumption.

The present invention solves the above-mentioned problems of the conventional apparatus, and makes it possible to reduce the heat capacity of the heating element without causing fixing failure or offset, thereby reducing standby time, power consumption, and It is an object of the present invention to provide an image forming apparatus that causes a small temperature rise inside the machine and has other remarkable features.

(Means for Solving the Problems) The present invention provides an image forming means that forms an unfixed toner image corresponding to target image information by supporting a toner made of heat-meltable resin or the like on the surface of a recording material; A fixing film, a traveling drive means for the fixing film, a heating body disposed on one side of the fixing film with the fixing film therein, and a heating body disposed on the other side of the fixing film, the fixing film being connected to the heating body through the fixing film. a pressure member that brings the unfixed toner image bearing side of the recording material into close contact with each other, and moves the recording material at the same speed and in the same direction as the recording material carrying the unfixed toner image transported from the image forming means side. a toner image heat fixing means for introducing the recording material between the running driven fixing film and the pressure member and heat fixing the unfixed toner image on the surface of the recording material, the toner image heat fixing means The image forming apparatus is characterized in that the fixing film has a rough surface on the side that contacts the toner image of the recording material.

Regarding the rough surface of the fixing film of the image forming apparatus having the above configuration, in particular, the roughness is 0.3 μm≦Rz≦10 μm (R2
The image forming apparatus is characterized in that the roughness is 10 points average roughness).

Furthermore, with regard to the rough surface of the fixing film, the image forming apparatus is particularly characterized in that the average interval of the unevenness having a depth of 0.3 μm or more is 50 μm or less.

(Function) (1) The recording material to which the image is to be fixed is introduced between the fixing film and the pressure member, which are running in the same direction at the same speed as the recording material conveyance direction, and the unfixed toner remains on the fixing film surface. When the image-bearing side is in close contact with the fixing film and is overlapping with the fixing film, the mutual pressure contact area (fixing nip area) between the heating body and the pressure member is subjected to squeezing pressure, and the surfaces may become misaligned or wrinkled due to the speed difference. They overlap as one and pass in close contact with each other without coming close to each other.

(2) Heating process During this process of passing through the mutual pressure contact section, the unfixed toner image on the surface of the recording material is softened and melted by heating by the heating body via the fixing film. In this case, the heating body, fixing film, toner image, and recording material are well pressed together by the pressure member at the mutual pressure contact portion of the heating member and the pressure member, and heat is transferred effectively, so that the heat is heated for a short time. The toner is sufficiently softened and melted to provide good fixing properties.

Here, a note will be made regarding the softening and melting of the toner described in the present invention. The temperature conveniently expressed as the toner's "melting point" refers to the minimum temperature required for the toner to fix. In some cases, the viscosity decreases to such an extent. Therefore, even if it is conveniently expressed as melting during fixing, the viscosity may actually decrease to the extent of softening. The present invention also includes such cases. Similarly, even when it is conveniently expressed that the toner has been cooled and fixed, depending on the toner, it may be more appropriate to say that the toner has become viscous rather than assimilated. The present invention also includes such cases.

■Cooling process The toner image that is in close contact with the fixing film surface and sequentially passes through the mutual pressure contact area of the heating body and the pressure member.The recording material portion that has been softened and melted by heating is kept in close contact with the fixing film surface even after passing through the pressure contact area. The conveyance is continued for a while, and this period is used as a cooling process, in which the heat of the toner softened and melted in the heating process is radiated, and the toner is cooled and fixed. This cooling and solidification greatly increases the cohesive force of the toner, causing it to behave as a group, and while the adhesion and fixing force to the recording material side increases, the cohesive force to the fixing film side extremely decreases. For the recording material, when the toner is heated and softened and melted in the heating process, it is pressed by the pressure member, so at least a part of the toner image penetrates into the surface layer of the recording material, and the permeated portion is cooled and assimilated. The anchor effect caused by this increases the adhesion and fixation power of the cooled and solidified toner to the recording material side.

(2) Separation (separation) process After the toner image is cooled and assimilated in the above cooling process, the recording material is sequentially separated from the fixing film surface. At this time of separation, the toner image is cooled and assimilated, and the adhesion/fixing force to the recording material is sufficiently large, but the adhesion and fixation force to the fixing film is extremely small, so the part of the recording material where the image has been fixed generates toner offset with respect to the fixing film. They are easily separated one after another without any problems.

In this way, the recording material on which the image is to be fixed is made to run in close contact with the fixing film at the same speed so that the unfixed toner image bearing surface faces the running fixing film surface, and the toner image is heated and melted by a heating body through the fixing film. In addition, since the recording material and the fixing film are separated after the toner image is cooled and fixed, toner offset with respect to the fixing film does not occur, and a heating element with a small heat capacity is used, and power is supplied to the heating element. This can be done with a simple configuration, and by maintaining the heating element at a temperature sufficiently high compared to the temperature (melting point or softening point) at which the toner should be heated for fixing, the toner image can be improved efficiently. This makes it possible to heat the image in a fixed amount of time, making it possible to achieve sufficiently good fusing with less energy and no fusing defects.As a result, an image forming device with less standby time during use, less power consumption, and less temperature rise inside the device can be obtained. This effect is achieved.

In addition, among the three steps of ■heating, ■cooling, and ■separation mentioned above, if the toner can be sufficiently melted at high temperature (if the viscosity of the toner is high enough when heated and melted), the toner can be sufficiently melted in the heating process. The recording material may be separated from the fixing film surface immediately after being melted at a high temperature (when the toner temperature is above the melting point), and the cooling step after the heating step may be omitted, and this is within the scope of the present invention. .

(2) As mentioned above, the unfixed toner image to be fixed on the recording material is located at the pressure contact area (fixing nip area) between the heating body and the pressure member.
In the heating process in which it passes through the fixing film, it is heated by a heating body through the fixing film, softening and melting (lowering the viscosity), and is brought into close contact with the surface of the fixing film by the pressure applied between the heating body and the pressure member. It solidifies in the cooling process while remaining in close contact (
Since the fixed toner image is separated from the fixing film after its viscosity is increased (increased viscosity), the outer surface shape of the fixed toner image that has been separated from the fixing film follows the surface shape of the surface of the fixing film on the side in contact with the toner image. Therefore, if the surface of the fixing film in contact with the toner image is too smooth, the surface of the fixing toner image will follow suit and become glossy, reducing image quality and quality.

In order to avoid this problem, toner images in a low viscosity state that have been softened and melted in the heating process are not sufficiently cooled and solidified and are essentially in the low viscosity state immediately after being softened and melted. Separation causes another problem in that a so-called high-temperature offset phenomenon tends to occur.

In the present invention, the surface of the fixing film in contact with the toner image is roughened, so that the surface shape of the fixed toner image follows the rough surface of the fixing film, thereby preventing the occurrence of gloss. This solves the problem of image quality deterioration due to gloss.

The specific degree of the above-mentioned rough surface of the fixing film was experimentally determined that the viscosity was 0.3 μm≦R,,≦10 μm, and the depth was 0.3 μm≦R, ≦10 μm.
It has been found that when the average interval of irregularities of 3 μm or more is 50 μm or less, there is no deterioration in image quality due to the gloss of the fixed toner image, or the image quality is small enough to be within a practical range.

(Embodiment) The apparatus of this embodiment is an electrophotographic copying apparatus of a reciprocating original table type, a rotating tram type, and a transfer type.

(1) Overall schematic configuration of the device (Fig. 1) In Fig. 1, 100 is a device housing, and 1 is a reciprocating motion consisting of a transparent plate member such as a glass plate disposed on the top plate 100a of the machine housing. There is a type document mounting table, and the top plate 100a of the machine casing is placed on the right side a in the drawing.
, are driven to reciprocate in the left direction a at predetermined speeds.

G is a document, which is placed by placing the image side to be copied facing down on the top surface of the document table 1 according to a predetermined placement standard, and placing the document pressure bonding plate 1a on top of it and pressing it down. .

Reference numeral 100b denotes a slit opening, which serves as a document illumination section, and is opened on the surface of the top plate 100a of the machine casing, with its length extending in a direction perpendicular to the direction of reciprocating movement of the document table 1 (direction perpendicular to the plane of the paper). The downward image surface of the document G set on the document platform 1 passes through the position of the slit opening 100b sequentially from the right side to the left side during the forward movement of the document platform 1 to the right side a. During the passage, the light from the lamp 7 is received through the slit opening 100b and the transparent original table 1, and the document is illuminated and scanned. The illumination scanning light reflected from the document surface is imaged and exposed on the surface of the photosensitive drum 3 by the short focus and small diameter imaging element array 2.

The photosensitive drum 3 is coated with a photosensitive layer such as a zinc oxide photosensitive layer or an organic semiconductor photosensitive layer, and is driven to rotate clockwise as shown by an arrow around a central support shaft 3a at a predetermined circumferential speed, and is charged during the rotation process. The charged surface is charged with positive or negative polarity by the device 4, and the image-forming exposure (slit exposure) of the above-mentioned yXM image is performed on the charged surface, so that the exposed original image is formed on the surface of the photosensitive drum 3. Electrostatic latent images corresponding to the images are sequentially formed.

This electrostatic latent image is sequentially visualized by a developing device 5 using toner made of a resin or the like that softens and melts when heated, and the developed toner image is transferred to a location where a transfer discharger 8 is provided as a transfer section. I will do it.

S is a cassette loaded with transfer material sheets P as recording materials, and the sheets in the cassette are fed one by one by the rotation of the feeding roller 6, and then the toner on the drum 3 is transferred by the registration roller 9. The timing is set so that when the leading edge of the image forming section reaches the position of the transfer discharger 8, the leading edge of the transfer material sheet P also reaches the open position of the transfer discharger 8 and the photosensitive drum 3, so that they are aligned. and fed synchronously. Then, a transfer discharger 8 is applied to the surface of the feeding sheet.
As a result, the toner images on the photosensitive drum 3 side are sequentially transferred.

The sheet to which the toner image has been transferred in the transfer section is sequentially separated from the three surfaces of the photosensitive drum by a separating means (not shown), and guided by a conveyance guide 10 to a fixing device 11, which will be described later, to heat the unfixed toner image carried thereon. After undergoing fixing processing, the image is discharged onto a paper discharge tray 12 outside the machine as an image-formed product (copy).

On the other hand, the surface of the photosensitive drum 3 after the toner image is transferred is subjected to removal of adhered contaminants such as residual toner by a cleaning device 13, and then turned over and used for image formation.

(2) Fixing device (Figures 1 and 2) 24 is an endless belt-shaped fixing film, which includes a drive roller 25 on the left side, a driven roller 26 on the right side, a separation roller 27 arranged below the drive roller 25, These four members 2 of the low heat capacity linear heating body 20 as a heating body arranged below between the driving roller 25 and the driven roller 26 are parallel to each other.
The suspension is installed between 5, 26, 27, and 20.

The driven roller 26 is an endless belt-shaped fixing film 2.
The fixing film 24 is fixed clockwise at a predetermined circumferential speed as the drive roller 25 rotates clockwise, that is, the unfixed toner image Ta conveyed from the image forming section 8 side. wrinkles, meandering, etc. at the same peripheral speed as the conveyance speed of the transfer material sheet P carrying the
Rotation is driven without speed delay.

Reference numeral 28 denotes a pressure roller having a rubber elastic layer such as silicone rubber with good mold releasability as a pressure member. The lower surface is pressed against the lower surface by a biasing means (not shown) with a total pressure of, for example, 4 to 7 kg, and is rotated in a forward counterclockwise direction in the conveying direction of the transfer material sheet P.

Endless belt-shaped fixing film 24 that is rotatably driven
The outer peripheral surface, that is, the surface of the transfer material sheet P serving as a recording material on the side that comes into contact with the toner image is roughened. This fixing film 24 will be described in detail in section (4) below.

The low heat capacity linear heating body 20 as a heating body is made of, for example, Ta2 along the longitudinal direction approximately at the center of the lower surface of the alumina substrate 21, which has a thickness of 1.0 mm, a width of 10 mm, and a length of 240 mm.
A linear or band-shaped heating element 22 is provided by coating an electrically resistive material such as N to a width of 1.0 mm.

In the case of this example, current is applied to the linear or band-shaped heating element 22 from both ends of its length to generate heat over the entire length of the heating element 22. Power supply is DClooV cycle 20m5e
The energization control circuit has a pulse-like waveform of c, and is configured to give a pulse according to the desired temperature and energy release amount controlled by the temperature detection element 23 by changing the pulse width, and the pulse width is approximately 0.5 to 0.5. It is controlled within a range of 5 m5 ec, and the heating element 22 instantly generates 200 cc each time a pulse is manually applied.
A-heat to around 300°C. Further, in this example, a sheet leading/trailing edge detection sensor (not shown) is provided closer to the fixing device on the upstream side in the transfer material sheet conveyance direction than the fixing device 11, and the heating element 22 is energized by the sheet detection signal from the sensor. The period is controlled to the required period during which the sheet P passes through the fixing device 11.

The fixing film 24 is not limited to an endless belt shape.
As shown in the figure, the fixing film 24 with an end wound around the feed-out shaft 30 is passed between the heating body 20 and the pressure roller 28 and under the separation roller 27, and then fixed to the take-up shaft 31. The transfer material sheet P may also be configured to run at the same speed as the conveyance speed of the transfer material sheet P from the feed-out shaft 30 side to the take-up shaft 31 side.

(3) Fixing execution operation The leading edge of the transfer material sheet P carrying the unfixed toner image Ta on the upper surface, which was conveyed from the transfer section 8 to the fixing device 11 by the image forming operation of the device in response to the image formation start signal, is connected to the fixing device. When detected by the above-mentioned sensor (not shown) disposed near the fixing film 24, the rotation (or running) of the fixing film 24 is started, and the transfer material sheet P is guided by the guide 29 and moved to the heating body 2.
The unfixed toner image surface enters between the fixing sheet 24 and the pressure roller 22 at the pressure contact portion N of the pressure roller 28 and the pressure roller 28, and the unfixed toner image surface is moved in the same direction at the same speed as the conveyance speed of the sheet P. The film passes through the mutual pressure contact portion N between the heating body 20 and the pressure roller 28 while being subjected to a clamping force while being in close contact with the lower surface of the fixing film 24 and being overlapped with the fixing film 24 without causing surface deviation or wrinkles. To go.

This process of passing through the mutual crimping part is referred to as the heating process (action).
The toner image is heated to soften and melt as described in item (1)-0. As described above, in the heating process in this embodiment, the heating element 20 is provided with the linear heating element 22, and the heating element 22, which is formed integrally with the heating element 21 and has a low heat capacity, is energized in a pulsed manner to repeatedly generate heat. Heating body 21 configured as follows.
It is carried out by That is, the toner image Ta on the sheet P conveyed at a predetermined conveyance speed, together with the fixing film 24 on which the sheet P is conveyed, is sequentially transferred to a linear heating section determined according to the width of the heating element 22 of the heating element 20. Within the effective width W
It is fed into the tank and heated to become a softened and fused image Tb.

The sheet portion that has passed through the mutual pressure contact portion N between the heating body 20 and the pressure roller 28 is spread between the heating body 20 and the separation roller 27 until it reaches the position of the separation roller 27, and is a fixing member that is traveling in the forward direction. It continues to be conveyed while remaining in close contact with the film portion.

This conveyance process is used as a cooling process in the above (action) (1)-
As described in item 0, the heat of the softened/melted toner Tb is radiated, and the toner is cooled and solidified Tc.

When the fixing film 24 reaches the position of the separating roller pair 27, the running direction of the fixing film 24 is turned away from the sheet P surface along the surface of the separating roller 27 having a large curvature, and the fixing film 24 and the sheet P are separated from each other (separated). ), and the sheet P is discharged to the paper discharge tray 11. By the time of this separation, the toner has sufficiently cooled and solidified and the above (action) (
1) As mentioned in item -0, the adhesion/fixing force of the toner to the sheet P is sufficiently large, and the force to the fixing film 24 is extremely small, so the separation of the fixing film 24 and the sheet P is caused by the This can be done easily and sequentially without substantial toner offset.

In this embodiment, the linear heating element 22 of the heating element 20 reaches the melting point (or fixable temperature) of the toner in a short time by applying electricity.
Since the temperature is raised to a sufficiently high temperature, preheating of the heating element is not necessary.

In the device of this embodiment having such a structure, the toner image made of heat-resistant toner on the sheet P is first heated and melted by the heating body 20 via the fixing film 24, and in particular, the surface layer portion thereof is completely softened. melt. At this time, the heating body, fixing film, toner image, and sheet are brought into close contact with each other by the pressure roller 28, and heat is efficiently transferred.

Thereby, the heating of the sheet P itself can be suppressed as much as possible, and the toner image can be efficiently heated and melted. In particular, by limiting the time for energization and heat generation, it is possible to save energy.

A small heating element is sufficient, so its heat capacity is small, and there is no need to heat up the heating element in advance, so power consumption during non-image formation can be reduced, and temperature rise inside the machine can also be prevented. .

(4) About the fixing film 24 The fixing film 24 has heat resistance, releasability, durability, etc.
In general, single or composite layer films of 100 .mu.m or less, preferably 40 .mu.m or less, can be used.

FIG. 4 is a schematic cross-sectional view of the layer structure of an example of a composite layer film, in which 24a is a heat-resistant layer as a base film of the fixing film, and 24b is the outer surface of the heat-resistant layer 24a (the surface facing the toner image). ), and the degree of freedom of this mold release layer is increased by roughening the surface 24c. This surface of the roughened release layer is the surface of the fixing film that is in contact with the toner image.

The heat-resistant layer 24a is made of, for example, polyimide, polyetheretherketone (PEEK), polyethersulfone (PES).
), polyetherimide (PE■), polyparabanic acid (
PPA), highly heat-resistant resin films such as PFA, and Ni
-3US-Au and other metals with excellent strength and heat resistance can be used.

The release layer 24b is preferably made of, for example, fluororesin such as PTFE (polytetrafluoroethylene)/PFA-FEP, silicone resin, or the like. Release layer 2 for heat-resistant layer 24a
The lamination of 4b is formed by adhesive lamination of the release layer film, lamination of the release layer material by electrostatic coating (coach ink), vapor deposition, CVD, etc., and co-extrusion of the heat-resistant layer material and the release layer material. This can be done by forming a layered film.

The surface roughening 24c of the release layer 24b is performed by sandblasting,
This can be done by mixing a filler into the release layer material, embossing, etc. FIG. 6 shows an example of enphos processing. That is, when laminating a film for the heat-resistant layer 24a and a film for the release layer 24b using a laminator, the release layer film 2
The pressure roller 105 on the 4b side is roughened by etching the outer circumferential surface of the pressure roller 105 to have a roughened surface with a depth of 2 μm.
An embossing roller) is heated by a heater 104 while a backup roller 103 and a roughening roller 105 are heated.
Both films 24a and 24b are laminated by applying pressure between them, and the outer surface of the release layer film 24b is roughened 2.
4c.

When the surface roughening 24c of the release layer 24b is particularly performed by sandblasting, if the adhesive strength between the heat-resistant layer 24a and the release layer 24b is weak, the release layer may peel off. To prevent this, it is recommended to adopt one or a combination of the following measures, or all of them.

(2) The surface of the heat-resistant layer 24a on which the mold release layer 24b is to be formed is sandblasted (R, 0, 1 to 5 μm) 17 in advance, and then the mold release layer 24b is laminated.

(2) The surface of the heat-resistant layer 24a on which the mold release layer 24b is to be formed is subjected to discharge treatment to form the mold release layer 24b.

(2) An adhesive layer of fluororesin or the like is provided between the heat-resistant layer 24a and the release layer 24b. The thickness of this adhesive layer is preferably thin in order to reduce the heat capacity of the fixing film, and is preferably 5 μm or less.

The fixing film 24 may be a single-layer film as long as it has both strength and releasability, and its outer surface can be roughened by the method described above.

For example, PFA reinforced with a filler can be used.

Specific Example 1 Heat-resistant layer 24a: Polyimide film with a thickness of 20 μm. Release layer 24b: PTFE mold release layer with a thickness of 10 μm. Roughness: Ten-point average roughness R2-2 μm, roughness 0. The average distance of unevenness of 3 μm or more is 5 μm or less The surface roughening 24c of the release layer 24b was carried out by sandblasting by spraying glass beads having a particle size of about 20 μm until the above roughness was achieved.

The surface shape of the fixed toner image obtained using this fixing film 24 follows the surface shape of the roughened release layer 24b of the fixing film 24, as schematically shown in FIG. 2 μm, and the average distance of the unevenness was 5 μm or less. As a result, the image quality deterioration of the fixed toner image was small and within a practical range.

Comparative Example 1 In the fixing film of Specific Example 1, when the surface of the release layer is not roughened, the R of the toner image side surface (release layer surface) of the fixing film is 0.1 μm or less. The fixed toner image obtained using such a fixing film has a smooth and glossy surface as shown in the example in FIG. 7, and there is no problem in terms of image quality.

According to experiments conducted by the present inventors while changing the sandblasting conditions of the fixing film, the R2 of the toner image side surface of the fixing film was 0.3 μm or more, and the average interval of unevenness with a depth of 0.3 μm or more was 50 μm or more. , preferably 20μ
m or less, there was no practical problem with the gloss of the fixed image.

Comparative Example 2 When a fixing operation was performed using the fixing film of Example 1 in which the thickness of the release layer 24b was set to 20 μm and the roughness R2 was set to 12 μm, The thickness of the fixing film becomes uneven, resulting in uneven fixing performance depending on location.

■The physical adhesion of toner to the fixing film increases, increasing the amount of offset toner.

According to experiments conducted by the present inventors, the upper limit of R2 that allows such a problem is 10 μm, but preferably 3 μm or less.

Specific example 2 Heat-resistant layer 24a... polyimide film release layer 24b with a thickness of 20 μm... PTFE film release layer 24b with a thickness of 10 μm mixed with SiO2 fine particles with an average particle size of 0.3 μm as a filler. No sandblasting after firing. However, due to the inclusion of the filler, the outer surface of the mold release layer 24b is R2=
Average distance of unevenness of 0.6μm, depth 0.3μm or more 1μ
The surface is in a roughened state of m. Therefore, a unique effect of this example is that there is no need for a separate surface roughening process such as sandblasting.

In addition to SiO2, the filler may be, for example, alumina, titanium oxide, titanium nitride, etc., and low-resistance substances such as metal particles or carbon black particles may also be used.

A unique effect of using a low-resistance material is that the volume resistivity of the release layer can be reduced to 1011 Ω・cm or less by mixing the material.
Preferably, by setting it to 10 7 Ω·cm or less, it is possible to prevent electrostatic offset of the toner by preventing the toner image contacting surface of the fixing film from being charged.

(5) In addition, when the fixing film 24 with ends is used as shown in FIG. It is also possible to use a replacement method (winding and replacement method).

In the case of such a winding and replacing type, it is possible to reduce the thickness of the fixing film regardless of its durability, and it is possible to reduce the power consumption. For example, the fixing film may be made of an inexpensive base material such as a PET (polyester) film, and may be heat-resistant treated and thin, for example, about 12.5 μm or less.

Alternatively, as mentioned above, toner offset to the fixing film surface does not substantially occur, so if the thermal deformation and deterioration caused by use of the fixing film are small, the used sheet that has been wound up on the winding shaft side can be moved in a timely manner. It is also possible to use it repeatedly by controlling the rewinding to the delivery shaft side, or by reversing and exchanging the take-up shaft side and the delivery shaft side (repetitive rewinding method).

For example, in the rewinding and reusable type, the fixing film is
A composite layer film can be used in which a 25 μm thick polyimide resin film is used as a base material with excellent heat resistance and mechanical strength, and a release layer made of a fluororesin or the like with high mold release properties is provided on the surface. At the time of rewinding and reverse running, the pressure release mechanism may be automatically controlled to maintain the contact between the heating body and the pressure roller in a released state.

If the film is to be used multiple times, such as in a rewinding type or an endless belt type, a felt pad is provided for cleaning the film surface, and the pad is impregnated with a small amount of release agent, such as silicone oil, and is brought into contact with the film surface. The film surface may be cleaned and the mold releasability may be further improved by cleaning the film surface. When the fixing film is treated with an insulating fluororesin, static electricity that disturbs the toner image is likely to be generated on the film, so it is a good idea to remove the static electricity using a grounded static eliminator brush. The film may be charged to the extent that the toner image is not disturbed by applying a bias voltage to the brush without being grounded. Furthermore, it is also a good idea to add conductive powder fibers, such as carbon black, to the fluororesin to prevent the above-mentioned image blur due to static electricity. Furthermore, the charge removal and conductivity of the pressure roller can be carried out by the same means. Also,
An antistatic agent or the like may be applied or added.

Regardless of whether the fixing film is of an endless belt type, a winding and replacing type, or a rewinding and reusing type, it is possible to facilitate the replacement of the fixing film by configuring a cartridge that can be attached to and removed from a predetermined part of the fixing device 11. can.

The configuration of the heating element 20 and the control of energization to the heating element 22 are not limited to those in the embodiment. The heating element 20 may be of a heat roller type, or the heating element 22 may have a thick film resistor or PTC characteristics. A ceramic chip array may also be used, and the energization control may be normal energization rather than pulsed energization control.

The toner heated and melted in the heating process may be cooled and solidified by natural heat radiation, or by forced cooling using a blower means, heat radiation fins, etc.

If the toner melts sufficiently at a high temperature, as shown in the example in Figure 8, if the toner is melted at a sufficiently high temperature in the heating process (fixing nip), it can be immediately transferred to the recording material (transfer material) without a cooling process after the heating process. The sheet) P may be separated from the fixing film 24 surface.

The above-described embodiments are transfer-type electronic copying devices, but the image forming process and means include a direct type in which a toner image is directly formed and carried on electrofax paper, electrostatic recording paper, etc., and a magnetic recording image forming type. Copying machines, laser beam printers, facsimile machines, microfilm reader printers, display devices, and recording machines that form an image using heat-fusible toner on a recording material using other appropriate image forming processes and means, and fix it by heating. The present invention can be effectively applied to various image forming apparatuses such as the above.

(Effects of the Invention) As described above, the present invention makes it possible to reduce the heat capacity of the heating body, which is the heating means, without causing fixation failure or offset in a toner image heat fixing type image forming apparatus, and to It is possible to realize an image forming apparatus that can always stably output an image formed product with good fixed image quality with less time, power consumption, and internal temperature rise. Furthermore, the thin fixing film can be used repeatedly over a long period of time without any problem of wrinkles.

Further, in the present invention, since the surface of the fixing film in contact with the toner image is made rough, the surface shape of the fixed toner image is covered by the rough surface of the fixing film, thereby preventing the occurrence of gloss. This eliminates the problem of image deterioration due to gloss.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional front view showing the schematic configuration of an embodiment of the apparatus, FIG. 2 is an enlarged view of the fixing device, FIG. 3 is a schematic diagram of another example of the fixing device configuration, and FIG. 4 is a diagram of the fixing film. Fig. 5 is a schematic diagram showing the surface shape of a fixed toner image; Fig. 6 is a process diagram of roughening the surface of the release layer by embossing; Fig. 7 is a glossy fixation diagram. FIG. 8, which is a schematic diagram showing the surface shape of a toner image, is a schematic diagram of another example of the structure of the fixing device. 3 is a drum-type rotating photoreceptor, 11 is a fixing device, 24 is a fixing film, 20 is a heating element, 28 is a pressure roller, and P is a transfer material sheet.

Claims (1)

[Scope of Claims] (1) An image forming means for forming an unfixed toner image corresponding to target image information by supporting toner made of heat-melting resin or the like on the surface of a recording material, a fixing film, and A means for driving the fixing film, a heating body disposed on one side of the fixing film, and a heating body disposed on the other side of the fixing film, and a means for moving the recording material through the fixing film to the heating body. A fixing device that is equipped with a pressure member that brings the toner image bearing side into close contact, and is driven to run in the same direction at the same speed as the conveyance speed of the recording material that carries the unfixed toner image that is conveyed from the image forming means side. a toner image heat fixing means for introducing the recording material between the film and the pressure member and heating and fixing the unfixed toner image on the surface of the recording material; the fixing film of the toner image heat fixing means is for recording. An image forming apparatus characterized in that a surface of the material that comes into contact with a toner image is a rough surface. (2) The image forming apparatus according to claim 1, wherein the rough surface of the fixing film has a roughness of 0.3 μm≦R_z≦10 μm (R_z is 10-point average roughness). (3) The image forming apparatus according to claim 1, wherein the rough surface of the fixing film has an unevenness having a depth of 0.3 μm or more and an average interval of 50 μm or less.