JP2002049257A - Fixing device and image-forming device having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a belt-fixing device with which the swelling of a fixing roller due to a releasing agent is prevented and also the quantity of the releasing agent on a fixing belt is controlled, while suppressing the deterioration of the fixing belt and an image-forming device having it. SOLUTION: This fixing device 1 has an endless fixing belt 2 for feeding a sheet-like medium on which toner is fixed; a heating roller 3 on which the fixing belt 2 is wound round and the fixing roller 4; a pressure roller 5 arranged to be counterposed to the fixing roller 4; and a releasing agent supplying means 19 provided with a roller 43 rotated with the fixing belt 2 and to supply the releasing agent; the fixing roller 4 has an isolating layer 40 to isolate a base body 10 from the releasing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device, and more particularly to a belt fixing device having a so-called endless belt and an image forming apparatus such as a copier, a facsimile or a printer having the fixing device.

[0002]

2. Description of the Related Art Image forming apparatuses such as copying machines, facsimile machines, printers, and printing machines generally have a fixing device for fixing a toner image on a sheet-like medium having a toner image as an image to be fixed. are doing.

[0003] The fixing device includes a heating roller having a heat source therein and driven to rotate, and a pressure roller pressed against the heating roller and rotated by the heating roller, and a nip formed by both rollers. A heat roller pair-type fixing device for fixing the toner image by heating and pressing the paper by rotating the rollers and an endless fixing belt and a fixing belt for conveying a sheet-like medium on which the toner is fixed. There is known a so-called belt fixing device of a type including a heating roller and a fixing roller around which a pressure roller is wound, and a pressure roller and the like arranged as opposed to the fixing roller via a fixing belt.

In general, a fixing device includes a releasing agent such as silicone oil for improving the releasability between a sheet-like medium and a member such as a fixing belt that comes into contact with the sheet-like medium. It has a release agent supply means for supplying to the member.

[0005]

In the belt fixing device, the width of the fixing roller is set to be larger than the width of the fixing belt in order to allow a certain amount of deviation of the fixing belt. Therefore, the release agent supplied to the fixing belt is transferred from both ends of the fixing belt to the fixing roller. Since the release agent at the end of the fixing belt does not adhere to the sheet-like medium and is not consumed, the transfer to the fixing roller occurs easily and in large amounts. On the other hand, the fixing roller is often made of an elastic material such as silicon rubber to secure a nip width, and such a material has a property of absorbing a release agent.
Therefore, the releasing agent supplied to the fixing belt is absorbed by the fixing roller over time, and the fixing roller swells with the releasing agent. When the fixing roller swells, the running of the fixing belt becomes unstable, and the conveyance of the sheet medium also becomes unstable, and the pressure at the nip causes problems such as generation of wrinkles and fixing defects in the sheet medium.

On the other hand, there has been known a configuration in which a blade is brought into contact with a fixing belt in order to control the amount of a releasing agent on a fixing belt supplied by a releasing agent supply unit. But,
When the blade is brought into contact with the fixing belt, there is a problem that the fixing belt deteriorates quickly. Although a configuration in which a roller is brought into contact with a fixing belt instead of a blade has also been proposed, conventionally, such a roller was driven to rotate at a relative speed to the fixing belt, so that the deterioration of the fixing belt also occurred. There is a problem that promotes.

Further, the linear velocity of the fixing belt is 80 mm / s.
If it is relatively slow below, per A4 size sheet,
It is sufficient to supply 0.5 mg or less of the release agent to the fixing roller. However, the linear velocity of the fixing belt tends to increase in recent years in order to increase the image forming speed. It is necessary to supply a release agent of 0.5 mg or more to the fixing roller per sheet. In particular, when a color image is formed, the linear velocity of the fixing belt is 156.
mm / s or more, and it is necessary to supply 3 to 4 mg of a release agent to the fixing roller per A4 size sheet. As described above, the amount of the release agent applied to the fixing belt tends to increase.
This promotes swelling of the fixing roller and deterioration of the fixing belt. That is, prevention of swelling of the fixing roller and deterioration of the fixing belt have been particularly important issues in recent years.

The present invention is directed to a belt fixing device for controlling the amount of a release agent on a fixing roller while preventing swelling of the fixing roller by the release agent and suppressing deterioration of the fixing belt, and an image having the fixing device. It is an object to provide a forming device.

[0009]

According to a first aspect of the present invention, there is provided an endless fixing belt for conveying a sheet-like medium on which a toner is fixed, wherein the fixing belt is wound around the endless fixing belt. A heating roller and a fixing roller,
In a fixing device, comprising: a pressure roller disposed to face the fixing roller via the fixing belt; and a release agent supply unit configured to supply a release material to the fixing belt. Further, the present invention is characterized in that it has an isolating layer for isolating the base of the identification applying roller from the release agent.

According to a second aspect of the present invention, in the fixing device of the first aspect, the material of the isolation layer is any one of fluororubber, fluorosilicone, Teflon, and latex.

According to a third aspect of the present invention, in the fixing device of the first aspect, the material of the base is silicon rubber.

The invention described in claim 4 is the first to third aspects of the present invention.
In the fixing device according to any one of the above, the release agent supply unit includes a first roller that is in contact with the fixing belt and that can rotate with the identification attaching belt.

According to a fifth aspect of the present invention, in the fixing device according to the fourth aspect, the release agent supply means contacts a first roller and supplies a release agent to the first roller. And a leveling member for leveling the layer thickness of the release agent on the first roller.

According to a sixth aspect of the present invention, in the fixing device according to the fourth aspect, the release agent supply means contacts the first roller and supplies the release agent to the first roller. A roller, driving means for rotating and driving the second roller, a supply member which abuts on the second roller and supplies the release agent to the second roller, and a supply member for the release agent on the second roller. And a leveling member for leveling the layer thickness.

The invention according to claim 7 is the invention according to claims 4 to 6
Wherein the first roller is disposed at a position facing the heating roller via the fixing belt.

According to the present invention, there is provided an endless fixing belt for conveying a sheet medium on which toner is fixed,
A heating roller and a fixing roller around which the fixing belt is wound; a pressure roller disposed to face the fixing roller via the fixing belt; and a release agent supply unit for supplying a release material to the fixing belt Wherein the release agent supply means has a first roller which comes into contact with the fixing belt and can rotate with the identification attaching belt.

According to a ninth aspect of the present invention, in the fixing device according to the eighth aspect, the release agent supply means contacts a first roller and supplies a release agent to the first roller. And a leveling member for leveling the layer thickness of the release agent on the first roller.

According to a tenth aspect of the present invention, in the fixing device according to the eighth aspect, the release agent supply means contacts the first roller to supply the release agent to the first roller. A roller, driving means for rotating and driving the second roller, a supply member which abuts on the second roller and supplies the release agent to the second roller, and a supply member for the release agent on the second roller. And a leveling member for leveling the layer thickness.

According to an eleventh aspect of the present invention, in the fixing device according to any one of the eighth to tenth aspects, the first roller is disposed at a position facing the heating roller via the fixing belt. It is characterized by having done.

According to a twelfth aspect of the present invention, there is provided an image forming apparatus having the fixing device according to any one of the first to eleventh aspects.

[0021]

FIG. 1 schematically shows a fixing device to which the present invention is applied and an image forming apparatus having the fixing device. The image forming apparatus is a well-known one such as a copying machine, a facsimile, a printer and the like, and may be any type of image forming apparatus that can use a fixing device to which the present invention is applied.
Although the image forming apparatus of the present embodiment forms a color image, it may form a single color image.

The image forming apparatus 20 includes image forming apparatuses 21C, 21Y, and 21 that form an image for each color according to a document image.
M, 21BK, image forming devices 21C, 21Y, 21M, 2
1BK, and a manual feed as sheet-like medium supply means for supplying various sheet-like media to a transfer area where the image forming apparatuses 21C, 21Y, 21M, 21BK and the transfer apparatus 22 face each other. Tray 23, paper cassettes 24, 24, manual tray 23, paper cassette 2
The image forming apparatus 2 converts the sheet-like medium conveyed from
1C, 21Y, 21M, 21BK, a registration roller 30 that supplies the sheet at the timing of image formation, and a fixing device 1 that fixes a sheet-like medium after transfer in a transfer area.
And

The image forming apparatus 20 includes plain paper (hereinafter simply referred to as plain paper) generally used for copying and the like, 90K paper such as an OHP sheet, a card and a postcard, and a basis weight of about 10
It is possible to use as a sheet medium any of thick paper having an equivalent weight of 0 g / m ² or more, and so-called special sheets (hereinafter simply referred to as special sheets) having a larger heat capacity than paper, such as envelopes.

Each image forming device 21C, 21Y, 21M, 21
BK develops the respective colors of cyan, yellow, magenta, and black, and uses different toner colors.
The configuration of C is changed to each image forming apparatus 21C, 21Y, 21M, 21
This will be described as a representative of BK. The image forming device 21C includes a photosensitive drum 25C as an electrostatic latent image carrier, and a photosensitive drum 2
It has a well-known configuration including a charging device 27C, a developing device 26C, a cleaning device 28C, and the like which are sequentially arranged in the rotation direction A of 5C, and receives exposure light 29C between the charging device 27C and the developing device 26C. The electrostatic latent image carrier may have a belt shape instead of a drum shape.

As shown in FIG. 2, the fixing device 1 includes an endless fixing belt 2 for conveying a sheet-like medium on which toner is fixed, a heating roller 3 around which the fixing belt 2 is wound, and a fixing roller 4. A pressure roller 5 disposed opposite to the fixing roller 4 via the fixing belt 2, heaters 6, 7, 17 provided inside the heating roller 3, the pressure roller 5, and the fixing roller 4; A thermistor 8 disposed opposite to the heating roller 3 via the fixing belt 2 as a temperature detecting means for detecting the temperature of the fixing belt 2, and disposed opposite to the pressure roller 5 to detect the temperature of the pressure roller 5 A thermistor 18 as a temperature detecting means, and a releasing agent supplying means 19 for supplying a releasing agent mainly composed of silicone oil to the fixing belt 2.

In order to apply an appropriate predetermined tension to the fixing belt 2, a tension is applied to the outer peripheral surface of the fixing belt 2 at a portion downstream of the fixing roller 4 in the rotation direction of the fixing belt 2 and upstream of the heating roller 3. The roller 31 is in elastic contact. The fixing roller 4 includes a core 9 and the core 9.
An elastic layer 10 made of heat-resistant porous silicon rubber as a base material, and a separating layer made of fluororubber formed on the surface of the elastic layer 10 to isolate the elastic layer 10 from a release agent. The heater 17 is built in the shaft 11 which is located at the center of the metal core 9. The separating layer 40 covers not only the surface of the elastic layer 10 but also the side surface of the fixing roller 4, and the inside of the fixing roller 4 is completely shielded from the release agent by the separating layer 40. The material of the isolation layer 40 may be fluorosilicone, Teflon, latex, or the like, in addition to fluororubber.

The fixing roller 4 integrally has a gear 32. The gear 32 is driven to rotate by a unit driving gear 33, whereby the fixing roller 4 is driven to rotate. Is driven. The unit driving gear 33 is driven to rotate by a main body driving gear 34 provided on the image forming apparatus 20 main body side. The unit driving gear 33 integrally has a gear 35 as a driving unit, and the release agent supplying unit 19 is driven by the gear 35.

The release agent supply means 19 includes an idler 36 meshed with the gear 35, an idler 38 meshed with a gear 37 integral with the idler 36, a supply gear 39 meshed with the idler 38, and an integral part of the supply gear 39. Supply roller 41
And a felt 45 as a supply member for supplying the release agent to the supply roller 41, and a release as a leveling member for elastically contacting the supply roller 41 and leveling the layer thickness of the release agent on the supply roller 41. The releasing agent is supplied by the supply roller 41 while being in contact with the agent regulating blade 42 and the supply roller 41, and the release roller is in contact with the fixing belt 2 and is capable of rotating with the fixing belt 2. A coating roller 43 disposed at an opposing position, and a spring (not shown) for urging the supply roller 41 in a direction of contacting the coating roller 43 and pressing the coating roller 43 against the fixing belt 2 with a predetermined pressure are incorporated. Biasing means 44.

The linear speed of the fixing belt 2, that is, the moving speed is 1
Although it is set to 60 mm / s and is set to be higher than the peripheral speed of the supply roller 41, the friction between the application roller 4 and the fixing belt 2, and the friction between the application roller 43 and the supply roller 41, make the application roller 43. Is adapted to rotate with the fixing belt 2. Further, since the application roller 43 is disposed at a position facing the heating roller 3 via the fixing belt 2, the fixing belt 2 is sandwiched between the application roller 43 and the heating roller 3. 2 of the fixing belt 2 without affecting the tension of FIG.
In the direction perpendicular to the plane of the drawing. The rotation of the application roller 43 along with the fixing belt 2 is caused by
Since there is no sliding resistance of the application roller 43 with respect to the fixing belt 2, it contributes to prevention of the deviation of the fixing belt 2,
Further, in order to improve the prevention of the deviation of the fixing belt 2,
It is desirable that the distance between the axes of the heating roller 3 and the application roller 43 be constant. Note that, in order to prevent the fixing belt 2 from shifting, a belt shift roller that satisfies at least one of these conditions may be disposed opposite the fixing roller 4.

The pressure roller 5 is urged by an elastic body (not shown) such as a spring in a direction in which the pressure roller 5 comes into pressure contact with the fixing roller 4. The pressure roller 5 is in contact with the fixing roller 4 at a position facing the fixing belt 5 with the fixing belt 2 interposed therebetween, whereby the nip where the pressure roller 5 is in contact with the fixing roller with the fixing belt 2 interposed therebetween. Is formed. On the upstream side of the fixing unit 16 in the rotation direction of the fixing belt 2 and the pressure roller 5, the sheet medium to be subjected to the fixing, which has been expanded by the image forming apparatus 20 and conveyed by the transfer device 22, is fixed. An upper guide 12 and a lower guide 15 for guiding toward the portion 16 are provided.

The fixing belt 2 is made of nickel and has a thickness of 100 mm.
A 200 μm release layer 14 made of silicon rubber is formed on a μm base 13, and has a small heat capacity and good thermal responsiveness. The base 13 may be made of polyimide, and the thickness may be about 30 to 150 μm in consideration of flexibility. The release layer 14 preferably has a thickness of about 50 to 300 when using silicone rubber, and has a thickness of about 10 to 50 μm when using a fluororesin-based resin. Further, the release layer 14 may have a configuration in which a fluororesin is laminated on silicon rubber. It is desired that the fixing belt 2 be heated instantaneously to the extent that hot offset does not occur. On the other hand, in the fixing region, the fixing belt 2 must have a heat capacity necessary to sufficiently melt and fix the toner. .
The above-mentioned material and thickness of the fixing belt 2 satisfy this condition.

The fixing belt 2 is given a tension of 3 kgf / one side by a tension roller 31. This tension can be set by adjusting the disposition position of the tension roller 31, from 1 kgf (9.8 N) to 3 kgf (2 Ng).
It is preferable to set it in the range of 9.4 N) in order to perform good fixing. The heating roller 3 and the pressure roller 5 are each made of a thin cylindrical cored bar to achieve low heat capacity. The diameter of the core of the heating roller 3 is 20 mm or more and 30 mm or less, the thickness of the concentric metal is 0.3 mm or more and 2.0 mm or less, and the diameter of the core of the pressure roller 5 is 30 mm or more and 50 m.
m or less, and the thickness of the concentric metal is 0.3 mm or more and 1.5 mm
It is as follows. Thereby, the heat capacity of the heating roller 3 becomes 26
cal / ° C. or less, heat capacity of the pressure roller 5 is 36 cal
/ ° C or less.

In this embodiment, the core of the heating roller 3 is made of aluminum, has a diameter of 30 mm and a thickness of 1.
5 mm. The surface of the metal core is alumite-treated. It is preferable that the material has a low specific heat and a high thermal conductivity, and other metals such as iron, copper, and stainless steel can be used. Roller diameter 30mm made of aluminum
When the thickness is in the range of 0.6 mm to 1.5 mm, the thickness is 0.7 mm to 1.4 when the roller is made of iron and has a roller diameter of 20 mm.
When the roller is made of iron and has a roller diameter of 30 mm, the thickness can be set in the range of 0.3 mm to 0.9 mm. The reason why the wall thickness is reduced as the diameter increases is in consideration of the axial bending of the roller.

The lower limit of the thickness is an allowable value in consideration of the deformation of the heating roller 3 due to the tension of the fixing belt 2, and the upper limit is an allowable value for obtaining a desired rise time. I have. The reason why the roller diameter is set to 20 mm or more is to secure the belt tension so that the roller does not bend in the axial direction. Roller diameter is 20mm
The reason for setting the sheet-like medium conveyance speed to 200 mm
mm / s or less, the fixing belt 2 even during continuous paper passing
26ca to keep the temperature of the toner at a constant temperature required for fixing.
This is for obtaining a heat capacity of about 1 / ° C.

By setting the heat roller 3 to have a low heat capacity as described above, even if the fixing belt 2 rotates, heat is hardly taken away, and adverse effects on fixing and prolonged rise time are prevented. . Further, even if the temperature is lowered due to continuous fixing or the like, the time until recovery is shortened. The heater 6 heats the fixing belt 2 via the heating roller 3 and the heating roller 3 so that the temperature in the fixing unit becomes 130 ° C. The detection signal from the thermistor 8 is fed back as the temperature of the heater 6. It is controlled by being done.

The elastic layer 10 of the fixing roller 4 is made of Asker C and has a relatively low hardness of 33 ° for the roller rubber hardness, which can be set in the range of 10 ° to 50 °. If the angle is less than 10 °, the nip pressure in the second fixing portion B is insufficient, so that the fixing of the toner becomes insufficient, and the fixing lower limit temperature must be increased. If the angle exceeds 50 °, wrinkles occur in the sheet medium. In consideration of the nip pressure and prevention of wrinkling of the sheet-like medium, it is desirable to set the angle to 33 ° as in this embodiment. The material is a heat-resistant porous elastic body with low heat conductivity and heat insulation, so it reduces the belt heat loss, reduces the temperature drop after rising, and increases the pre-rotation time for temperature recovery. Shortened. Further, since the elastic layer 10 has a relatively low hardness, a sufficient nip width can be obtained even when the pressing force of the pressure roller 5 is small, and good fixing performance can be obtained even under a relatively low temperature and low pressure condition. Obtainable. The layer thickness of the elastic layer 10 is 5 mm, and the layer thickness of the isolation layer 40 is 30 μm.

The pressure roller 5 has a cored bar and an elastic layer of silicon rubber formed on the surface of the cored bar.
It is made of iron, has a diameter of 30 mm and a thickness of 1.0 mm,
The elastic layer is made of silicone rubber and has a thickness of 2 mm. It is preferable that the material of the core metal has a low specific heat and a high thermal conductivity, and other metals such as aluminum, copper, and stainless steel can be used. In addition, when the roller diameter is 30 mm made of iron, the thickness is 0.4 mm to 1.0 mm.
In the case of iron and a roller diameter of 50 mm, the wall thickness is set to 0.1.
When the roller diameter is 30 mm, the thickness is 1.3 mm to 1.5 mm. When the roller diameter is 50 mm, the thickness is 0.6 mm to 1.0 mm. It can be set within a range of 2 mm. The reason why the wall thickness is reduced as the diameter increases is in consideration of the axial bending of the roller. The elastic layer is not always necessary, but when the elastic layer is provided, it is desirable to provide the same isolation layer as in the fixing roller 4 so as to cover at least the entire surface of the elastic layer.

The lower limit of the thickness of the core metal is determined by the fixing pressure.
0.6 kg / cm corresponding to the lower limit ^TwoPressure by surface pressure
The permissible value when the deformation of the roller 5 is considered,
An allowable value for obtaining a desired rise time is shown. Low
The roller diameter is set to 30 mm or more because the fixing pressure is secured and the roller
The range is such that the bending in the axial direction does not occur.
Further, the roller diameter is set to 30 mm to 50 mm because the sheet
When the medium transport speed is 200 mm / s or less,
The temperature of the fixing belt 2 is a constant temperature required for fixing even during continuous paper feeding.
To maintain a heat capacity of about 36 cal / ° C.
It is.

By setting the pressure roller 5 to have a low heat capacity as described above, even if the fixing belt 2 rotates, heat is less likely to be taken off. Since the pressure roller 5 has the heater 7, the temperature of the fixing belt 2 can be reduced. It is possible to prevent the toner from being lowered to adversely affect the fixing and to prolong the rise time. Further, even if the temperature is lowered due to continuous fixing or the like, the time until recovery is shortened. The heater 7 raises the temperature of the pressure roller 5,
In addition to shortening the start-up time, heat is also supplied from the back surface of the sheet-shaped medium during fixing to obtain more stable fixing performance. The pressure roller 5 can form a release layer of 10 μm to 300 μm on the elastic layer.

As shown in FIG. 3, the heaters 6 and 17 are connected to a power supply 46 as voltage applying means, and the heater 7 is connected to a power supply 47 as voltage applying means. It generates heat. The heaters 6 and 17 are connected in parallel to a power supply 46. The voltages of the power supplies 46 and 47 are both 100 V, the output W1 of the heater 6 is 650 W, and the output W2 of the heater 7 is 4
00W, the output W3 of the heater 17 is 150 W,
>W2> W3. The power supply 46 and the thermistor 8 are connected via a control means 48, and the power supply 47 and the thermistor 18 are connected via a control means 49.

The temperature detected by the thermistor 8 is compared with a set temperature of 175.degree.
When the temperature exceeds 175 ° C., the application of voltage to the heater 6 and the heater 17 by the power supply 46 is stopped.
The temperature detected by the thermistor 18 is compared with the set temperature of 150 ° C. by the control means 49, and when the temperature exceeds 150 ° C., the voltage application to the heater 17 by the power supply 47 is stopped. As described above, the heater 6 and the heater 17 are simultaneously controlled by the same power supply 46 based on the temperature of the fixing belt 2 on the heating roller 3. With this control, the temperature of the fixing roller 4 heated by the heater 17 becomes approximately 100 when stable.
℃. W1>W2> W described above
The relationship of 3 is to satisfy the condition for controlling the temperature of the fixing roller 4 in this manner.

The heater 17 can be connected not to the power supply 46 but to a power supply 47. In this case, the heater 7 and the heater 17 are simultaneously controlled by the same power supply 47. Become. Even when the heater 17 is connected to the power supply 47, it is desirable that the heater 717 be connected to the power supply 47 in parallel. Also, the heater 17
May be connected to a power source provided separately from the power sources 46 and 47. However, from the viewpoint of simplification of structure and control, the power source is connected to any of the power sources 46 and 47 as described above and the heater 6 or It is desirable to control simultaneously with either one of the heaters 7. It is known that the output of the heaters 6, 7, 17 is desirably 700 W or less in consideration of the inrush current when the power switch is turned on and the flickering phenomenon of the fluorescent lamp when the heater is turned on and off.

In the fixing device 1, the fixing roller 4 is
Therefore, the image formed on the first few sheet-shaped media in the image formation at the time of startup after the power of the image forming apparatus 20 is turned on, or in the image formation performed again after a while from the previous image formation Has improved glossiness. As shown in FIG. 4, in the image forming apparatus 20,
It is known that when the temperature of the heating roller 3 is lower than 145 ° C., the glossiness falls below the reference value of 10%, and the desired image quality cannot be obtained. However, as is apparent from FIGS. If it has, the temperature of the heating roller 3 is kept at 145 ° C. or higher from the first sheet passing, and the gloss
%, The temperature of the heating roller 3 is set to 1 in the first sheet passing when the heater 17 is not provided.
Below 45 ° C., the gloss is less than 10%. The number of sheets passed was five.

The reason that the temperature drop of the heating roller 3 is small when the heater 17 is provided is that the rotation of the fixing belt 2 is stopped after the pre-rotation is stopped at the time of startup or during the standby after the previous image formation. Is stopped, and thereafter, the rotation of the fixing belt 2 is started with the start of image formation. At the start of the rotation, the fixing belt 2 is warmed not only by the heating roller 3 but also by the fixing roller 4. Even if the belt 2 starts rotating, the heating roller 3
Does not cause a large temperature drop due to heat absorption by the fixing belt 2. Therefore, the heater 17
In this case, the temperature of the heating roller 3 is maintained at 145 ° C. or higher even when the sheet-like medium is passed, and good image formation can be performed. On the other hand, when the fixing belt 2 is not provided with the heater 17, the fixing belt 2 is heated only by the heating roller 3. This causes a large temperature drop. Therefore, when the first sheet is passed, the heat roller 3 is further heated by the heat absorbing action of the sheet medium.
, The desired image quality cannot be obtained.

FIGS. 5 to 7 show the case when the image forming apparatus 20 starts up after the power is turned on. However, the same result is obtained when the image forming apparatus 20 is on standby after a lapse of time from the previous image formation. I know. As is clear from FIGS. 5 and 6, when the temperature of the heating roller 3 reaches 150 ° C., the fixing belt 2 is pre-rotated, and the entire fixing belt 2 is heated to some extent. Although the temperature of the fixing belt 2 is different from that of the embodiment, a thermistor is disposed at a position facing the fixing roller 4 via the fixing belt 2 and the temperature is detected by the thermistor. Further, in the case where the sheet-shaped medium was continuously supplied and the fixing was performed, 90 kg paper was used, and when the single-color image formation was performed at 30 sheets / min, the color image formation was performed at 6 sheets / min. In each case, the fixability and glossiness were good. In particular, when a color image is formed, an image with optics is desired. However, if the image forming apparatus 20 of the present embodiment is used, a color image can be formed satisfactorily both at the start of image formation and during continuous paper feeding. I found that I could do it.

The fixing device 1 includes a plain paper mode in which fixing is performed when the sheet medium is plain paper, and a special sheet mode in which fixing is performed when the sheet medium is a special sheet.
Each of these modes may have a single color mode for forming a single color image and a color mode for forming a color image. In the present embodiment, these modes are switched by setting the special sheet mode when the manual feed tray 23 is used, and by switching between the monochrome mode and the color mode by the operation of the operator. It is also possible to automatically determine whether the sheet-shaped medium is a plain paper or a special sheet by a known means until the sheet-shaped medium reaches the fixing device 1, An operator can directly select a desired mode by pressing a key on an operation panel (not shown) provided on the main body side of the image forming apparatus 20, and the operator can perform the same operation. By specifying which paper feed cassette 24 to use, it is shown whether the sheet medium contained in the paper feed cassette 24 is plain paper or special sheet. There control means automatically determines and mode is switched accordingly, that can be can be performed indirectly by the operation of the operator via the control means.

The speed at which the sheet-like medium is conveyed by the fixing belt 2, ie, the fixing speed, can be changed in each mode. In this case, when the switching is performed, the fixing speed may be changed automatically. Alternatively, the fixing speed may be selected and changed by the operation of the operator. If the fixing speed is reduced, the amount of heat applied to the sheet-like medium in the fixing area increases, so that it is easy to obtain a glossy image. If a sufficient amount of fixing heat is applied, the degree of melting of the toner is increased, and the smoothness of the image surface is improved.

According to the present embodiment, when the power of the image forming apparatus 20 is turned on, the image forming apparatus 20 is in a state in which good fixing can be performed, the start-up is completed, and the image forming and fixing can be performed. Become. When the operator performs a well-known operation of starting image formation, the photosensitive drum 25C is charged by the charging device 27C with the rotation of the photosensitive member 25C in the direction A, and the photosensitive drum 25C is charged by the exposure light 29C according to the original image. A latent image is formed, this electrostatic latent image is developed by a developing device 26C, and the toner image formed on the photoconductor 25C is transferred onto a sheet-like medium conveyed in the direction of arrow B on a known transfer device 22. Then, the toner remaining on the photoconductor 25C after the transfer is scraped off by the cleaning device 28C to clean the photoconductor 25, and is used for the next charging.

The sheet-like medium to which the cyan toner has been transferred is conveyed in the direction of arrow B by the transfer device 22, and performs the same image forming process as the above-described image forming process in the image forming device 21C. 21M and 21BK sequentially transfer yellow, magenta and black toners as appropriate, transfer all the toner necessary for image formation, and then transfer the toner from the transfer device 22 to the fixing device 1 to transfer the upper guide 12 and the lower guide. 15 guides the fixing unit 16.

While the sheet-like medium is conveyed by the movement of the fixing belt 2, the toner is heated and pressed in the fixing unit 16 and is fused and fixed on the sheet-like medium. Even when continuous fixing is performed, heating by heaters 6, 7, 17
Heat is supplied to such an extent that hot offset does not occur, and good fixing is performed, and there is no need to interrupt fixing and perform reheating. The sheet medium after the fixing is discharged out of the image forming apparatus. According to the fixing device 1, the OHP
Even when fixing the sheet, a sufficiently large amount of fixing heat can be supplied as long as the fixing quality such as hot offset does not deteriorate, so that the OHP sheet surface is smoothed, irregular reflection is suppressed, and gloss is reduced. Is improved. Also, absorption and scattering of transmitted light are suppressed inside the toner, so that a good image can be formed.

With the fixing, the release agent is consumed by adhering to the sheet-like medium. However, the coating roller 43 is driven to rotate with the rotation of the fixing belt 2.
The release agent on the application roller 43 is supplied to the fixing belt 2. A release agent is supplied to the application roller 43 by the supply roller 41, and the release agent on the supply roller 41 is
After being supplied by the felt 45, the release agent regulating blade 42 uniformly uniforms the layer to an appropriate thickness, so that a uniform and appropriate amount of the release agent is supplied to the application roller 43. Therefore, the release agent, which is uniformly and appropriately controlled in a good amount, is also supplied to the fixing belt 2. In this embodiment, 3 to 4 mg of the release agent is supplied to the fixing belt 2 per A4 size sheet. The release agent is supplied to the fixing belt 2
The fixing belt 2 is also prevented from deteriorating because the rotation is performed by the roller-shaped application roller 43 that rotates.

Further, the release agent supplied to the fixing belt 2 is transferred from the end of the fixing belt 2 to the fixing roller 4. Since the fixing roller 4 has the isolation layer 40 formed thereon, Is not swollen by the release agent,
The running of the fixing belt 2 is stable over time, and the conveyance of the sheet-like medium is always performed in a stable manner, thereby preventing the generation of wrinkles and fixing defects of the sheet-like medium.

The fixing device to which the present invention is applied and the image forming apparatus provided with the fixing device have been described. The temperatures controlled by the control means 48 and 49 are constant in the present embodiment. The temperature can be changed as appropriate according to the temperature inside or outside the image forming apparatus 20 detected by a thermometer (not shown) provided in the apparatus 20, and the fixing belt 2, the heating roller 3, the fixing roller 4, the pressure roller 5 It should be adjusted according to the heat capacity and the like. The thickness and material of the fixing belt, the diameter, the thickness, and the material of the heating roller and the pressure roller can be appropriately combined.

The supply roller 41 is not always necessary, and a felt 45 may be applied to the application roller 43 to apply the release agent directly to the application roller 43. In this case, the release agent regulating blade 42 Provided for the application roller 43. According to this configuration, although the stability of the release agent supply is higher when the supply roller 41 is provided, the configuration of the release agent supply unit 19 can be simplified as compared with the case where the supply roller 41 is provided.

[0055]

According to the first aspect of the present invention, there is provided an endless fixing belt for conveying a sheet-like medium on which toner is fixed, a heating roller and a fixing roller around which the fixing belt is wound, In a fixing device including a pressure roller disposed opposite to the fixing roller via a fixing belt, and a release agent supply unit that supplies a release material to the fixing belt, the fixing roller has a surface Since the fixing roller has a separating layer for separating the base of the fixing roller from the release agent, the fixing roller does not swell due to the release agent,
It is possible to provide a fixing device in which the running of the fixing belt is stable over time, the conveyance of the sheet-shaped medium can be always performed stably, and the occurrence of wrinkles and fixing defects of the sheet-shaped medium can be prevented. it can.

According to a second aspect of the present invention, in the fixing device of the first aspect, the material of the isolation layer is any one of fluororubber, fluorosilicone, Teflon, and latex. It is possible to provide a fixing device capable of forming an isolation layer by selecting a suitable material.

According to a third aspect of the present invention, in the fixing device according to the first aspect, since the material of the base is silicon rubber, a nip required for fixing can be favorably formed between the base and the pressure roller. Since the swelling is prevented, it is possible to provide a fixing device capable of satisfactorily fixing.

The invention described in claim 4 is the first to third aspects of the present invention.
In the fixing device according to any one of the above, since the release agent supply unit includes the first roller that is in contact with the fixing belt and that can rotate with the identification attaching belt, the deterioration of the fixing belt is suppressed. A fixing device capable of supplying a release agent to the fixing belt can be provided.

According to a fifth aspect of the present invention, in the fixing device of the fourth aspect, the release agent supply means contacts a first roller and supplies a release agent to the first roller. And a leveling member for leveling the layer thickness of the release agent on the first roller, so that the amount of the release agent controlled to an appropriate amount can be stably formed on the fixing belt while the deterioration of the fixing belt is suppressed. A fixing device that can supply the fixing device can be provided.

According to a sixth aspect of the present invention, in the fixing device of the fourth aspect, the release agent supply means contacts the first roller and supplies the release agent to the first roller. A roller, driving means for rotating and driving the second roller, a supply member which abuts on the second roller and supplies the release agent to the second roller, and a supply member for the release agent on the second roller. Since there is provided a leveling member for leveling the layer thickness, it is possible to provide a fixing device having a higher release agent supply stability than when the release agent is directly supplied to the first roller by the supply member. it can.

The invention according to claim 7 provides the invention according to claims 4 to 6
In the fixing device according to any one of the above, since the first roller is disposed at a position facing the heating roller via the fixing belt, the fixing belt is disposed between the first roller and the heating roller. And a fixing device that can prevent the fixing belt from shifting.

According to the present invention, there is provided an endless fixing belt for conveying a sheet-like medium on which toner is fixed,
A heating roller and a fixing roller around which the fixing belt is wound; a pressure roller disposed to face the fixing roller via the fixing belt; and a release agent supply unit for supplying a release material to the fixing belt In the fixing device, the release agent supply means has the first roller which is in contact with the fixing belt and is capable of rotating with the identification fixing belt. A fixing device capable of supplying a mold agent can be provided.

According to a ninth aspect of the present invention, in the fixing device according to the eighth aspect, the release agent supply means contacts a first roller and supplies a release agent to the first roller. And a leveling member for leveling the layer thickness of the release agent on the first roller. Therefore, it is possible to provide a fixing device with a relatively simple configuration and high stability in supply of the release agent.

According to a tenth aspect of the present invention, in the fixing device according to the eighth aspect, the release agent supply means contacts the first roller to supply the release agent to the first roller. A roller, driving means for rotating and driving the second roller, a supply member which abuts on the second roller and supplies the release agent to the second roller, and a supply member for the release agent on the second roller. Provided is a fixing device which has a leveling member for leveling the layer thickness, and can stably supply an appropriate amount of a release agent, which is controlled to be uniform and appropriate, to the fixing belt while suppressing deterioration of the fixing belt. Can be.

According to an eleventh aspect of the present invention, in the fixing device according to any one of the eighth to tenth aspects, the first roller is disposed at a position facing the heating roller via the fixing belt. Therefore, it is possible to provide a fixing device in which the fixing belt is sandwiched between the first roller and the heating roller, and the deviation of the fixing belt can be prevented.

According to a twelfth aspect of the present invention, there is provided an image forming apparatus having the fixing device according to any one of the first to eleventh aspects. can do.

[Brief description of the drawings]

FIG. 1 is a side view schematically illustrating a fixing device to which the present invention is applied and a color image forming apparatus including the fixing device.

FIG. 2 is a side view of the fixing device shown in FIG.

3 shows a heater provided in the fixing device shown in FIG. 1,
It is the schematic which showed the aspect of connection of a voltage application means and a temperature detection means.

FIG. 4 is a correlation diagram showing a correlation between the temperature of a heating roller provided in the fixing device shown in FIG. 1 and the glossiness of an image formed on a sheet-like medium.

FIG. 5 is a correlation diagram showing a change in temperature in each section of the fixing device when the fixing device shown in FIG. 1 starts up, and is a correlation diagram showing a relationship between the number of sheet-passing sheets and the temperature. is there.

6 is a correlation diagram showing a change in temperature in each part of the fixing device when the fixing device in which the fixing roller is not provided with a heater as compared with the fixing device shown in FIG. FIG. 7 is a correlation diagram illustrating a relationship between the number of passed sheets and the temperature.

FIG. 7 shows the correlation between the number of sheets passed when the fixing device starts up and the glossiness of an image formed on a sheet-like medium, and shows the glossiness when the fixing roller has a heater and when it does not. FIG. 4 is a correlation diagram for comparison.

[Explanation of symbols]

REFERENCE SIGNS LIST 1 fixing device 2 fixing belt 3 heating roller 4 fixing roller 5 pressure roller 6 heater provided in heating roller 7 heater provided in pressure roller 8 temperature detecting means 10 base of fixing roller 17 heater provided in fixing roller 19 Release Agent Supply Means 20 Image Forming Apparatus 40 Separation Layer 43 First Roller 41 Second Roller 42 Equilibrium Member 45 Supply Member 46 The same voltage applying means as a heater and a fixing roller provided in a heating roller are provided. Voltage applying means for applying a voltage to the provided heater 47 Voltage applying means for applying a voltage to the heater provided on the pressure roller 48 First temperature detecting means 49 Second temperature detecting means

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) F16C 13/00 F16C 13/00 EZ (72) Inventor Genichi Yasui 1-3-3 Nakamagome, Ota-ku, Tokyo No. 6, Ricoh Co., Ltd. (72) Inventor Hiroshi Yoshinaga 1-3-6, Nakamagome, Ota-ku, Tokyo, Japan Ricoh Co., Ltd. (72) Hideo Furukawa, 1-3-6, Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Shoji Hayashi 1-3-6 Nakamagome, Ota-ku, Tokyo ・ Ricoh Co., Ltd. Ricoh Co., Ltd. (72) Inventor Kenichi Hasegawa 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd. (reference) 2H033 AA09 AA39 BA11 BA12 BA43 BA44 BA45 BB05 BB 06 BB28 3J103 AA02 AA15 AA24 AA33 AA41 AA51 BA02 BA34 BA41 BA43 FA03 FA05 FA09 FA12 FA21 GA02 GA57 GA58 GA60 GA66 HA03 HA04 HA05 HA13 HA18 HA41 HA43 HA47 HA53

Claims (12)

[Claims] An endless fixing belt for conveying a sheet-like medium on which toner is fixed; a heating roller and a fixing roller around which the fixing belt is wound; and a fixing roller opposed to the fixing roller via the fixing belt. And a release agent supplying means for supplying a release material to the fixing belt, wherein the fixing roller has a surface of an identification attaching roller on a surface of the release agent. A fixing device having an isolation layer for isolating the fixing device. 2. The fixing device according to claim 1, wherein the material of the isolation layer is any one of fluoro rubber, fluorosilicone, Teflon (registered trademark), and latex. 3. The fixing device according to claim 1, wherein a material of said base is silicon rubber. 4. A fixing device according to claim 1, wherein said release agent supply means has a first roller which comes into contact with said fixing belt and is capable of rotating with said identification attaching belt. A fixing device characterized by the above-mentioned. 5. A fixing device according to claim 4, wherein said release agent supply means contacts a first roller and supplies a release agent to said first roller. And a leveling member for leveling the thickness of the release agent. 6. A fixing device according to claim 4, wherein said release agent supply means contacts a first roller and supplies a release agent to said first roller. A driving unit for rotating and driving the roller, a supply member that contacts the second roller and supplies a release agent to the second roller,
A leveling member for leveling the layer thickness of the release agent on the roller. 7. The fixing device according to claim 4, wherein the first roller is disposed at a position facing the heating roller via the fixing belt. Fixing device. 8. An endless fixing belt for transporting a sheet medium to which toner is fixed, a heating roller and a fixing roller around which the fixing belt is wound, and facing the fixing roller via the fixing belt. A pressure roller, and a release agent supply unit that supplies a release material to the fixing belt, wherein the release agent supply unit contacts the fixing belt and contacts the identification attaching belt. A fixing device comprising a first roller that can rotate. 9. A fixing device according to claim 8, wherein said release agent supply means contacts a first roller to supply a release agent to said first roller, and a supply member for supplying said release agent to said first roller. And a leveling member for leveling the thickness of the release agent. 10. A fixing device according to claim 8, wherein said release agent supply means contacts a first roller and supplies a release agent to said first roller; A driving means for rotating and driving the roller, a supply member which comes into contact with the second roller and supplies the release agent to the second roller, and an equalizing means for equalizing the layer thickness of the release agent on the second roller. And a fixing member. 11. The fixing device according to claim 8, wherein the first roller is disposed at a position facing the heating roller via the fixing belt. Fixing device. 12. An image forming apparatus comprising the fixing device according to claim 1.