JP4950576B2 - Fixing device - Google Patents

Description

The present invention, in order to fix the unfixed toner image on the recording material is relates to a fixing device provided copiers, printers, an image forming apparatus such as a facsimile. In particular, the present invention relates to a technique for preventing a part of a fixed image from adhering to the fixing rotator side in a fixing device provided with a fixing rotator and a pressure rotator that are rotated in contact with each other to form a nip region.

  Conventionally, in an image forming apparatus using an image forming process such as an electrophotographic method or an electrostatic recording method, an electrostatic latent image is formed on a photosensitive drum or the like as an image carrier, and the latent image is formed using a developer. The toner image is developed and visualized as a toner image. The toner image is transferred onto a recording material such as paper, and then the recording material onto which the toner image is transferred is formed by a fixing roller and a pressure roller provided in the fixing device. By passing through the nip portion, the toner image is heat-fixed as a permanent image on the recording material.

FIG. 9 is a schematic configuration diagram of a main part showing a typical example of such an image forming apparatus. The surface of a drum-shaped electrophotographic photosensitive member (hereinafter referred to as “photosensitive drum”) as an image carrier that extends in the direction perpendicular to the paper surface and rotates in the direction of the arrow is connected to a high-voltage power source 2. Are uniformly charged. Next, a laser beam L modulated by an image signal is applied to the charged surface by the laser scanner 3 to form an electrostatic latent image. Toner is supplied to the latent image from the developing device 4 to become a toner image and arrives at the transfer nip portion _NT .

The transfer nip portion _NT includes a nip portion between the photosensitive drum 1 and the conductive transfer roller 5 in contact with the photosensitive drum 1, and the recording is performed at the timing when the toner image portion on the photosensitive drum 1 arrives at the transfer nip portion _NT. The material P is supplied and passes through the nip portion. At this time, a transfer bias is applied to the transfer roller 5 by the high voltage power source 6, and the toner image on the photosensitive drum 1 side is transferred to the recording material P. Thereafter, the recording material P carrying the unfixed toner image leaves the transfer nip portion _NT and is conveyed to the fixing device 9A.

  In recent years, there has been proposed a film heating type fixing device using a fixing method that suppresses power consumption as much as possible without supplying power to the fixing device 9A particularly during standby (see, for example, Patent Documents 1 to 4).

The fixing device 9A has a heat-resistant film (fixing film) 23 that slides with a heater (heating body) 22 as a fixing rotating body, and is pressed against the heater 22 through the film 23 as a pressure rotating body. A pressure member (pressure roller) 24 that forms the fixing nip portion N _F is provided.

The recording material having an unfixed toner image is formed between the fixing film 23 and pressure member 24 of the fixing nip portion N _F are nipped and conveyed from the heater 22 to be granted an unfixed toner image through the fixing film 23 It is fixed as a permanent image on the recording material by pressure heat the fixing nip portion N _F.

  Such a film heating type fixing device 9A can use a low heat capacity linear heating element as a heater and a thin film having a low heat capacity as a fixing film. Is possible.

Further, in this type of film fixing and heating type fixing device 9A, as a method for driving the fixing film 23, pressure is applied as a pressure member while applying tension using a dedicated conveying roller and a driven roller for conveying the fixing film. There are a system for conveying the fixing film between the roller and a tensionless system for driving the cylindrical fixing film with a conveying force of the pressure roller by rotationally driving a pressure roller as a pressure member. The former has the advantage that the transportability of the fixing film can be increased, and the latter has the advantage that the apparatus configuration can be simplified and a low-cost apparatus can be realized.
JP-A-63-313182 Japanese Patent Laid-Open No. 2-157878 JP-A-4-44075 JP-A-4-204980

  One of the problems in the fixing device is an offset phenomenon. This is a phenomenon in which a part of an unfixed toner image adheres to a fixing rotator that comes into contact during fixing and causes an image defect.

  Although these reasons are various, one of the biggest causes is an electrostatic force exerted on the toner image from the rotating body.

  In other words, the pressure rotator that contacts the back surface of the recording material carrying the unfixed toner image on its surface may be charged to a negative high potential by continuously conveying the recording material. And the negatively charged toner image are electrostatically repelled, resulting in an offset phenomenon.

  In order to prevent this offset phenomenon, it is preferable that the fixing rotator has the same polarity as the charge of the toner image, and the pressure rotator has a different polarity from the charge of the toner image.

  However, for example, when the surface of the fixing rotator is made of fluororesin and the surface of the pressure rotator is made of silicone rubber, the fixing rotator may be positively charged and the pressure rotator may be negatively charged. . This situation is disadvantageous for the offset phenomenon when the toner image is negatively charged.

  In particular, in the case of a pressure rotating body made of an insulating material such as silicone rubber as described above, it may rise to about −several kV due to frictional charging with the recording material, and the unfixed toner image is negative as described above. In the case of the toner charged in a negative direction, there is a problem that so-called electrostatic offset is easily generated, which is repelled from the surface of the negatively charged pressurizing rotator and moves to the fixing rotator.

  Therefore, a method for increasing the electrostatic adhesion force of the toner image to the recording material has been proposed. One is a method in which a bias voltage is applied to a pressure roller core, which is a pressure rotator, by a high-voltage power source to induce a charge having a polarity opposite to that of the toner image, thereby attracting and fixing the toner to the recording material.

  However, in this method, the roller layer is thick and the resistance of the pressure roller surface is low if the resistance is high, such as silicone rubber, the problem is that the efficiency is low, the cost is increased by using a high-voltage power supply, the circuit There was a problem of complication.

  In addition, a method has been proposed in which a bias voltage is applied to the fixing rotator side by a high voltage power source to induce a charge having the same polarity as the charge of the toner image and the toner is suppressed by a repulsive electric field. Cost increases due to use and circuit complexity are problems.

  Therefore, the surface potential of the pressure roller is reduced to a predetermined low potential that does not cause an offset by making the surface of the pressure roller, which is a pressure rotator, face the surface of the pressure roller, which is a pressure rotator, as a charge eliminating means. A technique for reducing the above has been proposed.

  However, even with this method, depending on the type of the pressure roller member and the recording material, there may be a case where the phenomenon of causing image defects on the recording material cannot be completely prevented.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to more effectively prevent a phenomenon in which a part of an unfixed toner image adheres to a fixing rotating body that contacts at the time of fixing and causes an image defect. to provide a fixing equipment as possible.

The above object is manually achieved in the fixing equipment according to the present invention. In summary, according to the present onset bright, a tubular film, a heater in contact with the inner surface of the film, and a pressure roller that forms a nip portion with the heater through the film, of the pressure roller A fixing device for fixing the unfixed toner image on the recording material by heating while conveying the recording material carrying the unfixed toner image at the nip portion.
The charge eliminating means is provided on a recording material between a charge eliminating member provided at a position facing the surface of the pressure roller so as to directly remove the surface of the pressure roller, and between the charge eliminating member and the surface of the film. There is provided a fixing device having an electrical conduction path in which a rectifying element is arranged so that a charge having the same polarity as the charge of the carried unfixed toner image moves to the surface of the film. .

  According to the present invention, a conduction path from the charge eliminating unit to the surface of the fixing rotator is ensured, and even if the recording material enters the fixing nip region, the charge of the unfixed toner image has the same polarity as that of the unfixed toner image on the surface of the fixing rotator. Hold the charge. This effectively suppresses the phenomenon that the surface of the fixing rotator is charged with a different polarity from that of the toner caused by frictional charging, etc., and the offset phenomenon that part of the toner image adheres to the fixing rotator and causes image defects. It can be effectively prevented.

  In addition, according to the present invention, it can be achieved without using a high-voltage power supply, so that it is possible to achieve low cost and circuit simplification.

  Hereinafter, the fixing device according to the present invention will be described in more detail with reference to the drawings. However, the dimensions, materials, shapes, relative arrangements, and the like of the components described in the following examples are not intended to limit the scope of the present invention only to them.

Example 1
First, referring to FIG. 1, illustrating an example of an image forming apparatus to which a fixing device and a constant wearing location according to the present invention is applied.

FIG. 1 shows a schematic configuration of an electrophotographic laser beam printer 11 which is an embodiment of an image forming apparatus to which the fixing device of the present invention is applied .

  In FIG. 1, an image forming apparatus 11 includes a drum-shaped electrophotographic photosensitive member, that is, a photosensitive drum 1 as an image carrier constituting an image forming unit. Further, a charging roller 2 as a charging unit, a laser scanner 3 as an exposure unit, and a developing device 4 as a developing unit are arranged around the photosensitive drum 1 as an image forming unit.

  The surface of the photosensitive drum 1 is uniformly negatively charged by the charging roller 2, and then laser light is irradiated by the laser scanner 3. The intensity of the laser light L applied to the photosensitive drum 1 is modulated based on an image signal sent from an external device to a laser beam printer.

  The negative charge disappears in the portion irradiated with the laser beam L on the photosensitive drum 1, and a potential difference is generated in the shape of the image to form an electrostatic latent image.

  The electrostatic latent image is conveyed to the opposite portion between the developing device 4 and the photosensitive drum 1 by the rotation of the photosensitive drum 1 in the direction of the arrow, and the electrostatic latent image is negatively charged by the developing device 4 as a developer. The toner is sequentially developed with the toner.

The toner image developed by the developing device 4 is sequentially transferred by the transfer roller 5 to the recording material P sent to the transfer nip portion _NT from the paper feeding device 10 as recording material supply means.

  A DC high voltage generator 6, which is a transfer voltage application unit, is connected to the transfer roller 5, and a positive transfer voltage is applied to the transfer roller 5. The DC high voltage generator 6 is controlled by a transfer voltage controller 7.

The recording material P onto which the toner image has been transferred at the transfer nip portion _NT is separated from the photosensitive drum 1 and sent out to the fixing device 9 as the photosensitive drum 1 rotates.

  Next, the configuration of the fixing device 9 will be described. In this embodiment, the fixing device 9 is a so-called tensionless type fixing device of a film heating method and a pressure rotating body driving method.

  First, a conventional tensionless type fixing device 9A will be described with reference to FIG. FIG. 2 is a cross-sectional view of the fixing device.

  The fixing device 9 </ b> A includes a fixing rotator 23 and a pressure rotator 24 that rotate in contact with each other to form a nip region. The fixing device 9A holds the recording material P carrying the unfixed toner image between the fixing rotator 23 and the pressure rotator 24 so that the unfixed toner image contacts the fixing rotator 23 in the nip region. The unfixed toner image is fixed on the recording material P.

  More specifically, the fixing device 9A is fitted into a film inner surface guide member 21 having heat resistance and rigidity, and a concave groove portion provided on the lower surface of the film inner surface guide member 21 along the length of the film inner surface guide member 21. And a fixed heater 22 that generates heat when energized. A cylindrical fixing film 23 as a fixing rotating body is disposed so as to surround the outer periphery of the film inner surface guide member 21 and the heater 22.

  The heater 22 uses a linear heater as a substrate structure. For example, the heater 22 includes an elongated heat-resistant, insulating, and heat-conductive substrate 22a whose longitudinal direction is perpendicular to the fixing film 23, and a central portion in the short direction on the surface side of the substrate 22a. A resistance heating element 22b is arranged along the longitudinal direction of the substrate. The surface of the heating element on which the resistance heating element 22b is formed is protected by a heat-resistant overcoat layer 22c, and a feeding electrode 22d is connected to the longitudinal end of the resistance heating element 22b. Further, a temperature measuring element 22e such as a thermistor for detecting the temperature of the resistance heating element 22b is disposed on the back side of the substrate 22a.

  Then, as described above, the film inner surface guide member 21 in which the heater 22 is fitted has the outer peripheral length of about 57 mm, and a cylindrical heat-resistant resin fixing film 23 is loosely fitted from the outside.

  As shown in FIG. 3, the fixing film 23 is composed of, for example, three layers, a polyimide layer having a thickness of 50 μm as the base layer 31, a conductive adhesive layer 32 having a thickness of several μm thereon, and a fluororesin having a thickness of several μm. Of the top layer 33. The inner peripheral length of the fixing film 23 is 3 mm larger than the outer peripheral length of the film inner surface guide member 21 including the heater 22, and the fixing film 23 has a margin in the peripheral length with respect to the film inner surface guide member 21 including the heater 22. It is externally fitted loosely.

  As shown in FIG. 2, the pressure roller 24 constituting the fixing device 9 </ b> A is a pressure roller (pressure roller, drive roller) as a pressure rotator, and the inner surface of the film including the pressure roller 24 and the heater 22. A fixing film 23 is sandwiched between the guide member 21.

  The pressure roller 24 is a rotation composed of a cored bar 25 and a heat-resistant rubber such as silicone rubber and fluorine rubber formed concentrically on the cored bar 25 or an elastic layer 26 formed by foaming silicone rubber or the like. Is the body.

Although not shown, the pressure roller 24 is disposed such that both end portions of the core metal 25 are rotatably supported by bearings between the front and back side plates of the apparatus chassis via bearing members. Then, the pressure roller 24 and the film inner surface guide member 21 forms each other is fixed so as to be pressed against the fixing nip portion (nip area) N _F.

The pressure roller 24 is driven to rotate at a predetermined peripheral speed by the rotation control unit 8. The outer surface and the fixing film 23 of the pressure roller 24 by the rotation of the pressure roller 24, the rotational force acts on the cylindrical fixing film 23 by the pressure contact frictional force in the fixing nip N _F. As a result, the fixing film 23 is driven to rotate on the outer periphery of the film inner surface guide member 21 while the inner surface side is in close contact with the downward surface of the heater 22 and slides.

The recording material P is between while energizing the heater 22, in a state where the heater 22 is heated is temperature control rising to a predetermined temperature, the fixing film 23 and pressure roller 24 of the fixing nip portion N _F Is introduced in a state where an unfixed toner image T is carried thereon.

Then, the toner image carrying surface side of the recording material P is nip portion N _F pinched and conveyed together with the fixing film 23 in close contact with the outer surface of the fixing film 23 in the fixing nip portion N _F. In this nipping and conveying process, the heat of the heater 22 is applied to the recording material P through the fixing film 23, and the unfixed toner image T on the recording material P is heated and pressed on the recording material P to be melt-fixed. Is done. The recording material P passed through the fixing nip portion N _F is the curvature separated from the fixing film 23.

  The laser beam printer 11 that performs the above-described operation has the following problems.

When the recording material P carrying the unfixed toner image T on the surface is continuously conveyed, the pressure roller 24 may be negatively charged due to friction between the recording material P and the pressure roller 24. This phenomenon, when the recording material P bearing the unfixed toner image T on the surface passes through the fixing nip portion N _F, the toner image negatively charged, i.e., negative charge of the toner T is the pressure roller 24 and the electrostatic Therefore, the toner T adheres on the fixing film 23 without being fixed on the recording material P. The fixing film 23 is round, adhering the toner T when the toner T enters the fixing nip N _F were again adheres onto the recording material P, is the offset phenomenon.

  Next, the fixing device 9 of this embodiment will be described with reference to FIG.

  The fixing device 9 of the present embodiment has the same configuration as the above-described conventional fixing device 9A, and members having the same configuration and function are denoted by the same reference numerals, and the description of the conventional fixing device 9A is incorporated. To do.

In this embodiment, since the surface of the pressure roller 24 is made of an insulating material of silicone rubber, the recording material P carrying the negatively charged unfixed toner image T on the surface is fixed to the pressure roller 24. the surface potential of the passes through the fixing nip portion N _F pressure roller 24 with the film 23, charged particularly large negative.

  For example, if the process speed is set to 100 mm per second, letter size (LTR size) paper is used as the recording material P, and processing is performed at a speed of 16 sheets per minute, the pressure roller 24 from about −3 kV to −6 kV depending on the type of the recording material P. Is charged.

  Therefore, in this embodiment, the fixing device 9 having the configuration shown in FIG. 4 is used.

  That is, in the fixing device 9 of the present embodiment, the static elimination needle 41 is fixed to the paper feed guide 27 as the static elimination means, and the tip of the static elimination needle 41 is disposed so as to have a certain distance from the surface of the pressure roller 24. ing.

  Further, a conduction path K1 is arranged from the static elimination needle 41 to the conductive adhesive layer 32 of the fixing film 23, and a charge having the same polarity as the charge of the unfixed toner image from the static elimination needle 41 toward the fixing film 23 is provided on the path K1. A moving rectifier element (diode) D1 is arranged. The output end of the diode D1 is connected to the brush electrode 42 which is a contact electrode, and the brush electrode 42 is in electrical contact with the conductive adhesive layer 32 of the fixing film 23 in this embodiment. .

As described above, the recording material P bearing the unfixed toner image T is negatively charged on the surface, passes through the fixing nip portion N _F of the pressure roller 24 and the fixing film 23, the surface potential of the pressure roller 24 Is negatively charged. In the case of the above configuration, the surface potential of the fixing film 23 is about 0 to +100 V, and the surface potential of the pressure roller 24 is −several kV.

  Due to the potential difference, the negative charge charged on the surface of the pressure roller 24 passes through the conduction path K1 from the tip of the static elimination needle 41 to the surface of the fixing film 23 or near the surface via the diode D1, It flows into the conductive adhesive layer 32 through the brush electrode 42. As a result, the surface potential of −several kV of the pressure roller 24 is reduced to near 0 V, and electrostatic repulsion between the negatively charged toner T and the pressure roller 24 across the recording material P is eliminated. As a result, the toner T is fixed not on the fixing film 23 but on the recording material P, and the offset phenomenon that occurs when the toner T adheres to the fixing film 23 can be alleviated.

  FIG. 5 shows a fixing device 9B having a configuration in which the static elimination needle 41 is provided in the conventional fixing device 9A shown in FIG. 2 in the same manner as the fixing device 9 of this embodiment. However, the fixing device 9B is different from the fixing device 9 of this embodiment in that the static elimination needle 41 is grounded. Other configurations are the same.

  That is, the major difference between the fixing device 9 of this embodiment shown in FIG. 4 and the fixing male value 9B of the configuration shown in FIG. 5 is that the place where the discharging current from the discharging needle 41 flows is the fixing device of this embodiment. 9 is the surface of the fixing film 23 or in the vicinity of the surface, which is the conductive adhesive layer 32 in the present embodiment, whereas the fixing device 9B shown in FIG. 5 is grounded.

  The configuration of the fixing device 9 of the present embodiment can increase the static elimination effect as compared with the fixing device 9B shown in FIG. 5 in which the static elimination needle 41 connected to the ground is arranged in the conventional configuration shown in FIG.

  The potential difference between the pressure roller 24 and the fixing film 23 has a great influence on the static elimination effect. The potential difference in the configuration of FIG. 5 is a difference of 0 V (ground) and −several kV (the surface of the pressure roller 24). On the other hand, in the configuration of the fixing device 9 of this embodiment, the potential difference is about +100 V (the surface of the fixing film 23) and −several kV (the surface of the pressure roller 24). Becomes larger.

  FIG. 6 shows the surface potential value of the pressure roller 24 when a plain paper (Xerox 4024) having a basis weight of 75 g is printed at a process speed of 100 mm per second in the configuration including the conduction path K1 and the diode D1 in the configuration of the present embodiment. .

  6, the configuration of the conventional fixing device 9 </ b> A shown in FIG. 2 is provided with a static elimination needle connected to the ground (fixing device 9 </ b> B shown in FIG. 5), and the configuration of the fixing device 9 of the present embodiment shown in FIG. 4. Shown in comparison.

  In the configuration of the present embodiment, the static elimination effect on the surface of the pressure roller is larger than the configuration of the fixing device 9B that directly grounds from the static elimination needle 41 without passing through the fixing film 23. The difference is getting bigger. After passing 20 sheets continuously, the surface potential reaches +300 to +500 V in the configuration of the present embodiment (first embodiment), and a difference of about 600 V is generated from the configuration in which the static elimination needle 41 is directly connected to the ground. Yes.

  With this effect, it is possible to more effectively prevent an offset phenomenon in which a part of the toner adheres to the fixing film 23 that is in contact with the fixing and causes image defects.

  In addition, the above configuration can be achieved without using a high-voltage power supply, so that it is inexpensive and simplification of the circuit can be achieved.

Example 2
Next, a second embodiment of the present invention will be described with reference to FIG.

  The fixing device 9 of the second embodiment has the same configuration as that of the fixing device 9 of the first embodiment. Members having the same configuration and function are denoted by the same reference numerals, and the fixing device 9 of the first embodiment ( And the explanation made about the conventional fixing device 9A) is used, and the explanation here is omitted.

The configuration of the fixing device 9 of Example 1 can prevent the occurrence of offset. However, when the recording material P enters the fixing nip portion N _F leaving the positive transfer voltage applied from the transfer roller 5, positive charges are accumulated in the fixing device 9. For example, in a low humidity environment, the amount of charge accumulated in the fixing device 9 becomes large. This is because the resistance increases because the amount of moisture contained in the recording material P decreases in a low humidity environment, and when the transfer bias is applied with a constant current in this state, the voltage increases as the resistance of the recording material P increases. This is because of this.

  Thus, depending on the operating environment, the positive transfer voltage applied to the recording material P becomes too large, and the surface of the fixing film 23 may be positively charged.

  In the present embodiment, in addition to the configuration of the first embodiment, an earth path K <b> 2 that is grounded (grounded) via the brush electrode 42 from the conductive adhesive layer 32 that is on the surface of the fixing film 23 or in the vicinity of the surface is provided.

  In the path K2, a rectifying element (diode) D2 is arranged so that charges of an unfixed toner image and charges different in polarity move toward the ground. With this configuration, the positive charge applied to the recording material P at the time of transfer is not held by the fixing film 23 by flowing into the ground through the ground path K2.

  As described above, in the present embodiment, the ground path K <b> 2 is provided with the diode D <b> 2 for holding the negative charge obtained by the charge removal of the pressure roller 24 in the fixing film 23.

  In the configuration of the second embodiment, since the potential difference between the pressure roller 24 and the fixing film 23 is reduced by several hundred V compared to the configuration of the first embodiment shown in FIG.

  However, in the fixing film 23, the positive charge is eliminated by the ground path K2 and the diode D2, and the negative charge obtained by the charge removal is supplied from the pressure roller 23, so that the surface potential is effectively prevented from being offset. Can be induced and stabilized in a negative direction.

  Since the fixing film 23 is a rotating body that is in direct contact with the toner T, the surface potential is more sensitive than the potential of the pressure roller 24. Therefore, even if the neutralization effect of the pressure roller 24 is slightly reduced, the configuration that easily induces the surface potential of the fixing film 23 to the minus side is effective for preventing the offset.

  Further, in the configuration of the present embodiment, the potential on the surface of the fixing film has a polarity effective for preventing the offset, as compared with the conventional configuration of the fixing device 9A shown in FIG. It can be induced.

  FIG. 8 shows the surface potential value of the fixing film when plain paper (Xerox 4024) having a basis weight of 75 g is printed at a process speed of 100 mm per second with the configuration including the ground path K2 and the diode D2 according to the present embodiment. . In FIG. 8, the configuration of the conventional fixing device 9A shown in FIG. 2 is compared with the configuration of the fixing device 9 of this embodiment shown in FIG.

  The surface potential of the fixing film 23 is about + 150V during paper passing in the configuration of the conventional fixing device 9A, whereas it is induced to the minus side up to about + 50V in the configuration of the fixing device 9 of this embodiment. .

  In the first and second embodiments, the tensionless type fixing device including the fixing film 23 and the pressure roller 24 has been described. However, the principle of the present invention is that the fixing device uses a fixing roller instead of the fixing film 23. It is also applicable to. It can also be implemented in pressure fixing using the pressure of both rotating bodies.

  Further, the image forming apparatus is not limited to the printer described in the first embodiment, and may be a color image forming apparatus, and other various image forming apparatuses provided with a fixing device known to those skilled in the art. It can be.

1 is a schematic configuration diagram of a laser beam printer showing an embodiment of an image forming apparatus to which a fixing device according to the present invention is applied. It is a schematic block diagram of the conventional tensionless type fixing device. 3A and 3B are diagrams illustrating a configuration of a fixing film, in which FIG. 3A is a cross-sectional view, and FIG. 3B is a front view. 1 is a schematic configuration diagram of a first embodiment of a fixing device according to the present invention. It is a schematic block diagram of the conventional tensionless type fixing apparatus provided with the static elimination needle. It is a figure which shows the surface potential transition of the pressure roller in a 1st Example and a prior art example. It is a schematic block diagram of the 2nd Example of the fixing device which concerns on this invention. It is a figure which shows the surface potential transition of the fixing film in a 2nd Example and a prior art example. It is a schematic block diagram of the conventional laser beam printer.

Explanation of symbols

1 Photosensitive drum (image carrier)
2 Charging roller (charging means)
3 Laser scanner (exposure means)
4 Developing device (Developing means)
5 Transfer roller (transfer means)
6 Transfer High Voltage Generating Device 7 Transfer Voltage Control Unit 8 Rotation Control Units 9, 9A, 9B Fixing Device 10 Paper Feed Device 11 Laser Beam Printer 21 Film Inner Surface Guide Member 22 Heater 23 Fixing Film (Fixing Rotator)
24 Pressure roller (Pressure rotating body)
25 Pressure roller core 26 Pressure roller elastic layer 27 Paper feed guide 31 Fixing film: Base layer 32 Fixing film: Conductive adhesive layer 33 Fixing film: Top layer 41 Static elimination needle (static elimination means)
42 Brush electrode (contact electrode)
L Laser beam N _F Fixing nip (nip area)
N _T transfer nip P recording material T unfixed toner image K1 conduction path K2 from the static elimination needle to the fixing film diode D2 between the fixing film and ground D1 diode between K1 (rectifier element)
Diode between D2 and K2 (rectifier element)

Claims (2)

A cylindrical film, a heater in contact with the inner surface of the film, a pressure roller that forms a nip portion together with the heater via the film, and a static elimination means that neutralizes charges on the surface of the pressure roller. A fixing device for fixing the unfixed toner image on the recording material by heating while conveying the recording material carrying the unfixed toner image at the nip portion,
The charge eliminating means is provided on a recording material between a charge eliminating member provided at a position facing the surface of the pressure roller so as to directly remove the surface of the pressure roller, and between the charge eliminating member and the surface of the film. An electrical conduction path provided with a rectifying element so that a charge having the same polarity as that of the carried unfixed toner image moves to the surface of the film . A ground path in which a rectifying element is disposed so that charges having a polarity opposite to that of the unfixed toner image carried on the recording material from the surface of the film to the ground side move;
The fixing device according to claim 1, wherein the ground path is branched from the electrical conduction path .

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