JP4651421B2 - Fixing device and image forming apparatus provided with the fixing device - Google Patents

Description

  The present invention relates to a fixing device and an image forming apparatus including the fixing device, and in particular, a fixing device having high cleaning capability and capable of maintaining the prevention of back surface contamination of transfer paper for a long period of time, and The present invention relates to an image forming apparatus including the fixing device.

  In image forming apparatuses such as copying machines, printers, and fax machines, toner is attached to an electrostatic latent image formed on a photosensitive drum, and the attached toner is transferred to a transported recording medium (transfer paper) and transferred. There is a type in which a later transfer paper is heated and fixed by a heat fixing means, and a toner image is fixed to the transfer paper (electrophotographic system).

An example of this type of conventional image forming apparatus (printer) will be described with reference to FIG.
FIG. 8 is a schematic configuration diagram of a conventional printer. The printer includes a color printer and a monochrome (monochrome) printer. FIG. 8 is an example of a monochrome printer.

  As shown in FIG. 8, the printer 100 includes a charging unit 102, a developing unit 104, a transfer unit 105, a drum cleaning unit 106, and a charge removing unit 107 around the photosensitive drum 101. A registration roller pair 108 and a heat fixing unit 109 are provided on the side of the transfer unit 105. Further, an exposure unit and a sheet feeding unit (not shown) are also provided. P is transfer paper.

  The photosensitive drum 101 is rotated counterclockwise by a driving unit (not shown). The charging unit 102 uniformly charges the surface of the rotating photosensitive drum 101. The above-described exposure means scans the laser beam L based on an image signal sent from a personal computer (hereinafter referred to as a personal computer) or the like, and forms an electrostatic latent image on the surface of the photosensitive drum 101 after uniform charging. Form. This electrostatic latent image is conveyed to the developing area of the developing unit 104 as the photosensitive drum 101 rotates.

The developing unit 104 includes a storage unit that stores toner, a stirring paddle that stirs the toner, a developing roll, a regulating blade, and the like.
The toner is attached only to the electrostatic latent image on the photosensitive drum 101 and develops the electrostatic latent image into a toner image.

  The transfer unit 105 stretches the endless paper transport belt 105c by two stretching rollers 105a and the transfer roller 105b, and rotates it clockwise by at least one of the rollers. Further, a contact / separation mechanism (not shown) is provided so that the paper transport belt 105c is brought into contact with and separated from the photosensitive drum 101.

  In the vicinity of the exit of the transfer nip formed by the contact between the paper conveyance belt 105c and the photosensitive drum 101, the transfer roller 105b is in contact with the back surface (the inner surface of the loop) of the paper conveyance belt 105c. A transfer bias having a polarity opposite to that of the toner is applied to the transfer unit 105 by a power source (not shown), and a transfer electric field is formed in the transfer nip by this application.

  On the other hand, a paper feeding unit (not shown) feeds the transfer paper P at a predetermined timing and sandwiches it between the rollers of the registration roller pair 108. The registration roller pair 108 sends the transfer paper P sandwiched between the rollers toward the transfer nip at a timing at which the transfer paper P can be superimposed on the toner image developed on the photosensitive drum 101.

  The transfer paper P that has entered the transfer nip by this feeding has its front surface (upper surface) superimposed on the toner image on the photosensitive drum 101. Then, after the toner image is electrostatically transferred from the surface of the photosensitive drum 101 to the front surface due to the influence of the transfer electric field and the nip pressure, the toner image exits the transfer nip. Next, the paper is conveyed toward the heat fixing unit 109 as the paper conveying belt 105c rotates.

  The heat fixing unit 109 includes a heating roller 109a having a heater such as a halogen lamp therein, a pressure roller 109b pressed against the heating roller 109a by a spring (not shown), and a cleaning roller 109c that rotates while contacting the pressure roller 109b. And a separation claw 109d. Also provided is a surface temperature detecting means 109e for detecting the surface temperature of the heating roller 109a.

  The surface temperature detecting means 109e outputs a signal corresponding to the surface temperature of the heating roller 109a to a heater power source (not shown). The heater power supply adjusts the power supply amount to the internal heater of the heating roller 109a based on this signal. Thereby, the surface temperature of the heating roller 109a is maintained within a predetermined range.

  The heating roller 109a is rotated counterclockwise by driving means (not shown). The pressure roller 109b abuts on the heating roller 109a to form a fixing nip, and rotates following the rotation of the heating roller 109a. The transfer paper P fed into the heat fixing means 109 is sandwiched between the fixing nips so that its front surface is in close contact with the heat roller 109a.

  Then, the toner image is fixed on the front surface due to the heating by the heating roller 109a and the influence of the nip pressure. After the toner image is fixed, the transfer paper P passes through the fixing nip, is separated from the heating roller 109a by the separation claw 109d, and is then discharged out of the printer.

A slight amount of offset toner transferred to the surface of the heating roller 109a at the fixing nip is transferred from the surface of the heating roller 109a to the surface of the pressure roller 109b at the fixing nip, and further transferred to the surface of the cleaning roller 109c.
A cleaning blade (not shown) is in contact with the surface of the cleaning roller 109c, and the offset toner transferred to the surface of the cleaning roller 109c is scraped and removed (see, for example, Patent Document 1).

As the cleaning means, conventionally, the following system is known.
(1) The above-described cleaning roller method (cleaning roller 109c in FIG. 8): This method has a drawback that the cleaning roller is accompanied by the heating roller, so that the life is long, but the cleaning ability is not high.
(2) Cleaning blade method: This method has good cleaning properties when conditions (such as the degree of sliding contact between the heating roller and the cleaning blade) match, but it is difficult to determine the conditions.
In addition, since it slides with the mating member (heating roller), the life of the heating roller and the cleaning blade may be shortened.
Furthermore, due to the sliding, there is a drawback that the heating roller may be damaged by the toner fixed to the cleaning blade over time.

In order to solve these drawbacks, a cleaning web system is employed in high-speed machines of image forming apparatuses. Here, the cleaning web method is a method in which a roll-like cloth soaked with oil is disposed opposite to the pressure roller, and the offset toner adhered to the surface of the pressure roller by sliding the cloth against the pressure roller. This is the removal method.
However, the cleaning web method has sufficient cleaning ability and life, but has a disadvantage that the cleaning device becomes complicated and large.

By the way, in the monochrome printer, oil-less fixing in which oil is not applied to the fixing member (fixing (heating) roller) by using a wax-containing toner.
On the other hand, in the conventional color printer, oil having excellent releasability is applied to the fixing member. The reason is that the toner adhesion amount is increased by forming a color image by superposing a plurality of color toners, and the releasability is inferior to that of the monochrome toner due to the characteristics of the color toner.

Japanese Patent Laid-Open No. 2004-271539

However, due to recent market demands (maintenance-free, pen writing on the surface of transfer paper, etc.), oilless fixing with wax-containing toner is also progressing in color machines (color printers).
In the case of oilless fixing, a contact type separation claw (for example, the separation claw 109d in FIG. 8) is required for separating the transfer paper from the fixing member for the following reason.

  That is, in the low / medium speed machine having a relatively low transfer paper conveyance linear speed, the transfer paper is separated from the fixing member by the curvature + non-contact separation plate method. However, in high-speed machines with fast transfer paper linear speeds, the fixing nip is widened to ensure fixability, so the fixing roller diameter increases, and contact-type separation with better transfer paper separation performance than the non-contact separation plate method. Transfer paper separation by a nail (hereinafter simply referred to as a separation nail) is required.

  When the separation claw is in contact with the fixing member, offset toner accumulates at the contact point and downstream thereof. The offset toner accumulated on the separation claw is fixed to the fixing member (heating roller 109a) when the fixing unit (the heating fixing unit 109 in FIG. 8) is stopped, and when the fixing unit rotation of the next job (job = printing operation) starts. May fall from the separation claw. In this case, the dropped toner moves from the fixing member (heating roller) to the pressure roller, and adheres to the back surface of the first sheet of the job as toner contamination.

In order to prevent the toner on the back surface of the transfer paper from being contaminated, it is necessary to reliably collect the toner dropped from the separation claw with a cleaning mechanism.
Here, in FIG. 8, the cleaning roller 109c is used as the above-described cleaning mechanism. However, as described above, the cleaning roller system has a long life because the cleaning roller is brought along with the pressure roller 109c, but has a drawback that the cleaning capability is not high.

  The present invention has been made to solve the above-described problems, and has a high cleaning capability and a fixing device capable of maintaining the back surface of the transfer paper for a long period of time, and the fixing device. An object is to provide an image forming apparatus provided.

In order to achieve this object, the toner image on the transfer paper is fixed by the fixing means (the fixing roller 10 in FIG. 1A) and the pressure means (the pressure roller 20), and then the transfer paper is separated from the fixing means. In the fixing device provided with the contact type separation means (11) for
A fixing unit (TU) that does not include a sliding cleaning unit in the fixing unit and that lowers the releasability of the transfer paper of the pressure unit than the fixing unit;
Offset toner cleaning means (cleaning device 30) for removing offset toner adhering to the pressure means;
Control means (control device 40) for controlling the offset toner cleaning means,
The control means is a control in which the offset toner cleaning means slides or comes into contact with the pressurizing means for a short time immediately after the start of the printing operation, and does not slide or come into contact during printing (FIG. 1B). ) .

  The above configuration is illustrated in FIGS. 1A and 1B, for example. In this way, by making the releasing means of the pressing means worse (lower) than the fixing means, the toner dropped from the contact-type separation claw means or the like to the fixing means is transferred to the pressing means side, and the fixing means By not having a sliding cleaning means, it is possible to prevent sliding flaws of the fixing means.

  Further, since the offset toner cleaning means slides or contacts the pressurizing means only for a short time immediately after the start of the job, and does not slide or contact during the job (printing), the dropped toner at the start of the job It can be reliably removed by the offset toner cleaning means to prevent the transfer paper from being stained. Further, since the offset toner cleaning means and the pressure means (both means) do not slide or abut during the job, the wear of both means can be reduced and the life of both means can be extended.

The front Symbol control means (control device 40), the offset toner cleaning to means (first cleaning device 31 in FIG. 3) is the pressure means (pressure roller 20), the printing operation immediately after the start of the short A configuration may be adopted in which control is performed only for time and not during printing .

  The above configuration is illustrated in FIGS. 3A and 3B, for example. In this way, the offset toner cleaning unit abuts against the pressurizing unit only immediately after the start of the job, and is separated during the job, so that the dropped toner is surely removed at the start of the job, and the backside of the transfer paper is removed. Can be prevented. In addition, since the offset toner cleaning unit and the pressurizing unit do not contact each other during the job, both the units are less worn, and the life of both units can be extended.

The front Symbol offset toner cleaning unit may be configured is the pressure means during the cleaning (pressure roller 20) in contact with the cleaning blade (cleaning blade 31a in Figure 3 (A)).
The above configuration is illustrated in FIGS. 3A and 3B, for example .

The front Symbol offset toner cleaning unit may be configured a contact with a felt cleaning pad (32a in FIG. 4 (A)) to the pressurizing means at the time of cleaning.

  The above configuration is illustrated in FIGS. 4A and 4B, for example. In this case, by using a felt cleaning pad for the offset toner cleaning means, the offset toner is reliably removed at the time of contact, and the toner damped to the cleaning pad is entangled with the felt fibers. At the time of separation, it is possible to make it difficult for the toner to remain in the pressure unit.

The front Symbol offset toner cleaning means comprises comprises a roller (cleaning roller 33a in FIG. 5 (A)),
The control means (control device 40) controls the rotation of the roller so as to abut against the pressing means for a short time after the start of printing, and the rotation of the roller to the pressing means during printing. It is good also as composition which performs .

  The above configuration is illustrated in FIGS. 5A and 5B, for example. In this way, a roller is used for the offset toner cleaning unit, and the offset toner on the pressurizing unit is reliably removed by contacting the pressurizing unit with rotation stopped for a short time immediately after the start of the job. By rotating, the wear of the pressing means and the cleaning roller is prevented and a long life is achieved. Further, since it is not necessary to contact or separate the offset toner / cleaning means, the configuration is simple, and the accumulated toner can be prevented from falling on the pressure means.

The front Symbol offset toner cleaning means comprises comprises a roller (cleaning roller 33a in FIG. 6),
The control means causes the roller to slide on the pressure means (pressure roller 20) with a linear speed difference for a short time after the start of printing, and also rotates the roller to the pressure means during printing. It is good also as a structure which performs control to perform .

  The above configuration is illustrated in FIGS. 6A and 6B, for example. In this way, for a short time immediately after the start of the job, the offset toner on the pressure unit is driven by driving with a linear velocity difference between the roller and the pressure unit, and sliding the roller with the pressure unit. Can be reliably removed. Further, during the job, since the roller is not rotated and does not slide with respect to the pressure unit, wear of the pressure unit and the offset toner cleaning unit can be prevented and a long life can be achieved.

  Also, when cleaning, the roller is not stopped and rotated with a difference in linear velocity, so that the toner stains are not biased in the circumferential direction of the roller, and the offset toner adheres uniformly to the cleaning roller, resulting in a longer service life. Can be

The front Symbol roller (cleaning roller 35a in FIG. 7 (A)) may be is made of felt.

The above configuration is illustrated in FIGS. 7A and 7B, for example. By this way, by the offset toner cleaning means is a felt roller, contact time or removes at reliably offset toner slide, and, since the dammed toner is entangled in the fibers of the felt, brought It is difficult to re-transfer to the pressurizing means during rotation.

The image forming apparatus may be configured to include the fixing device.
In this way, it is possible to reliably remove the offset toner generated in the image forming apparatus and extend the lifetimes of both the pressure unit and the offset toner cleaning unit. Therefore, for example, even a color image forming apparatus can meet demands such as maintenance-free and pen writing on the transfer paper surface.

According to the first aspect of the present invention, by using a roller for the offset toner cleaning unit, the offset toner on the pressurizing unit is surely removed by contacting the pressurizing unit with the rotation stopped for a short time immediately after the start of the job. Can be removed. Further, since the cleaning roller is rotated during the job, wear of the pressing means and the cleaning roller is prevented, and a long life is achieved. Further, since it is not necessary to contact or separate the offset toner / cleaning means, the construction is simple, and the accumulated toner can be prevented from falling on the pressure means.

According to the second aspect of the present invention, a roller is used as the offset toner cleaning unit, and the roller is driven with a linear velocity difference for a short time immediately after the start of the job and is slid with the pressurizing unit. The offset toner can be reliably removed. Further, by not sliding along with the job during the job, wear of the pressurizing means and the offset toner cleaning means can be prevented, and a long life can be achieved.
In addition, when cleaning, the roller is rotated with a linear speed difference without stopping, so that the toner contamination is not biased in the circumferential direction of the roller and the toner adheres uniformly to the cleaning roller, thus extending the service life. can do.

According to the third aspect of the present invention, by the offset toner cleaning means is a felt roller, the toner was stopped Ki allowed is entangled in the fibers of the felt, difficult to re-transferred to the pressing means when turns with.

According to the fourth aspect of the present invention, the offset toner generated in the image forming apparatus can be surely removed, and the lifetimes of both the pressurizing means and the offset toner cleaning means can be extended. Therefore, for example, even a color image forming apparatus can meet demands such as maintenance-free and pen writing on the transfer paper surface.

<Basic concept of the present invention>
In the present invention, the toner to be surely removed is one that has fallen from the separation claw at the start of rotation of the unit (for example, the heat fixing unit 109 in FIG. 8). There is no need to recover.
Therefore, in order to achieve a long life while reliably preventing “back stain” due to toner dropping from the separation claw with a simple configuration as much as possible, the following may be performed.
(1) The cleaning member is “slidably contacted” with the fixing member for a short time immediately after the start of the unit rotation in which the toner falls from the separation claw.
(2) During other unit operations, the cleaning member is not “slidably contacted” with the fixing member.

Here, in this specification, “abutment” means that a stationary object is brought into contact with an opponent (for example, the tip of the cleaning blade 31a in FIG. Further, the cleaning roller 33a in FIG.5A is stopped and brought into contact with the pressure roller 20).
“Sliding” means that two objects are in contact with each other in a moving state and slide with a linear velocity difference (for example, between the pressure roller 20 and the cleaning roller 33a in FIG. 6A). Both slide with a linear velocity difference).
Furthermore, both “contact” and “sliding” are collectively referred to as “sliding contact”.

In addition, when the cleaning member is provided on the fixing member, there arises a problem that the fixing member is damaged due to a change with time, particularly when the cleaning member is stained with toner. On the other hand, since the surface of the pressure member (pressure roller) is normally in contact with the back surface of the transfer paper, the releasability is not required as much as the fixing member (a slight amount of toner is allowed).
Therefore, it is advantageous for moving the offset toner on the surface of the fixing member to the surface of the pressure member and collecting the offset toner on the surface of the pressure member by the cleaning member to damage the fixing member.

The surface of the fixing member is required to have high releasability with respect to the toner. Generally, a material having good releasability has a low surface hardness and tends to be easily damaged. When the fixing member is scratched, a solid image or the like becomes a glossy streak and the image quality is remarkably deteriorated.
Further, as described above, FIG. 8 shows a monochrome printer, but the cross-sectional shape of the heat fixing means (fixing unit TU described later) is the same for both color printers and monochrome printers.

  Prior to describing the present invention based on the illustrated embodiment, the concept of the present invention and a fixing device (fixing unit) used in the embodiment of the present invention will be described below.

<Concept Description of the present invention>
1A and 1B are diagrams showing the concept of the present invention, in which FIG. 1A is a schematic configuration diagram of a fixing unit and cleaning means (both are collectively referred to as a fixing cleaning device), and FIG. 1B is a timing chart of the fixing cleaning device. is there.
As shown in FIG. 1A, the fixing unit TU includes a fixing roller 10, a pressure roller 20, and a separation claw 11 (details will be described later).
A cleaning device 30 is disposed below the pressure roller 20 so as to be capable of “sliding (contacting or sliding)” against the pressure roller 20. A control device 40 is connected to the cleaning device 30 and performs the control described below.

Next, the operation of the present invention will be described.
As shown in FIG. 1B, under the control of the control device 40, the fixing motor (not shown) is turned on for a short time immediately after the start of the job, and at the same time, the cleaning member of the cleaning device 30 (see the following embodiments). “Sliding contact” with respect to the pressure roller 20 is started.

  The offset toner that has fallen onto the fixing roller 10 from the separation claw 11 at the start of rotation of the fixing unit TU passes through the fixing nip before the transfer paper (not shown) arrives at the fixing nip. Due to the difference in releasability between the fixing member (fixing roller 10) and the pressure member (pressure roller 20), the offset toner moves to the surface of the pressure roller 20 after passing through the fixing nip.

The offset toner that has moved onto the pressure roller 20 is scraped off by the cleaning member that “slidably contacts” the pressure roller 20 and is removed from the pressure roller 20.
Five seconds after the start of rotation of the fixing motor, the “sliding contact” between the pressure roller 20 and the cleaning member is completed. The fixing motor continues to rotate until the fixing operation ends (Job ends).

<Description of fixing roller>
Next, the configuration of the fixing unit used in common with each embodiment described below will be described.
FIG. 2 is a schematic side view of the fixing unit TU.
As shown in FIG. 2, the fixing roller 10 has a diameter of 50, a silicon rubber layer having a thickness of 4 mm on the surface of an aluminum core, and the outermost surface is covered with a PFA tube. Here, PFA is a tetrafluoroethylene perfluoroalkyl vinyl ether copolymer resin.

The pressure roller 20 has a diameter of 50 mm, a silicon rubber layer with a thickness of 2 mm on the surface of an aluminum core, and the outermost surface is covered with a PFA tube.
A halogen heater (not shown) is disposed inside each of the fixing roller 10 and the pressure roller 20 and is controlled by a temperature control device (not shown).

The fixing roller 10 and the pressure roller 20 are driven during a fixing operation by a fixing motor (not shown). The fixing unit TU is stopped during standby, but starts rotating at a job start (print start).
At a fixing nip formed by the fixing roller 10 and the pressure roller 20, a toner image is fixed by applying heat and pressure to a transfer sheet (not shown).
A separation claw 11 for separating the fixing roller 10 and the transfer paper P is disposed on the downstream side of the fixing roller 10.

(1) First embodiment (reference example)
3A and 3B are diagrams illustrating this embodiment, in which FIG. 3A is a schematic configuration diagram of a fixing cleaning device, and FIG. 3B is a timing chart of the fixing cleaning device. In addition, the same code | symbol is attached | subjected to the already demonstrated part and duplication description is abbreviate | omitted.

As shown in FIG. 3A, below the pressure roller 20, a first cleaning device 31 described below is arranged so as to be able to “contact” the pressure roller 20. A control device 40 is connected to the first cleaning device 31 and performs the following control.
The first cleaning device 31 includes a cleaning blade 31a that can contact and separate from the pressure roller 20, a fulcrum 31b that rotatably supports the cleaning blade 31a, a spring 31c that separates the cleaning blade 31a from the pressure roller 20, and a cleaning blade 31a. Is provided with a solenoid 31 d that “contacts” the pressure roller 20.

Next, the operation of this embodiment will be described.
As shown in FIG. 3B, when the solenoid 31d is turned on, the tip of the cleaning blade 31a "contacts" the pressure roller 20, and the offset toner is cleaned.
As in the above “Description of the concept of the present invention”, the solenoid 31d is turned on for 5 seconds after the job starts, and the cleaning blade 31a “contacts” the pressure roller 20 to perform cleaning. After 5 seconds, the solenoid 31d is turned off and the cleaning blade 31a is separated from the pressure roller 20. Then, cleaning is not performed until the end of the job.

(2) Second embodiment (reference example)
4A and 4B are diagrams illustrating this embodiment, in which FIG. 4A is a schematic configuration diagram of a fixing cleaning device, and FIG. 4B is a timing chart of the fixing cleaning device.
As shown in FIG. 4A, a second cleaning device 32 described below is disposed below the pressure roller 20 so as to be able to “contact” the pressure roller 20. A control device 40 is connected to the second cleaning device 32 and performs the following control.

  The second cleaning device 32 includes a felt cleaning pad 32a that can be brought into and out of contact with the pressure roller 20, a lever 32b having the cleaning pad 32a attached to the tip, a fulcrum 31b that rotatably supports the lever 32b, and a cleaning pad 32a. And a solenoid 31d for “contacting” the cleaning pad 32a with the pressure roller 20.

Next, the operation of this embodiment will be described.
As shown in FIG. 4B, when the solenoid 31d is turned on, the cleaning pad 32a “contacts” the pressure roller 20 to clean the offset toner.
As in the above “Description of the concept of the present invention”, the solenoid 31d is turned ON for 5 seconds after the job starts, and the cleaning pad 32a “contacts” the pressure roller 20 to perform cleaning. After 5 seconds, the solenoid 31d is turned off and the cleaning pad 32a is separated from the pressure roller 20. Then, cleaning is not performed until the end of the job.

(3) The third embodiment forms state Figure 5, a diagram showing the present embodiment, (A) is a schematic structural view of a fixing cleaning device, (B) is a timing chart of the fixing cleaning device.
As shown in FIG. 5A, below the pressure roller 20, a third cleaning device 33 described below is disposed so as to be able to “contact” the pressure roller 20. A control device 40 is connected to the third cleaning device 33 and performs the following control.

The third cleaning device 33 includes a cleaning roller 33a that can be rotated with respect to the pressure roller 20, and a brake 33b that is attached to a shaft end (not shown) of the cleaning roller 33a and stops the rotation of the cleaning roller 33a. I have.
The cleaning roller 33a is a φ14 sponge roller covered with a PFA tube having a surface layer of 20 μm. The positions of the pressure roller 20 and the cleaning roller 33a are fixed with a fixed shaft (not shown), and the amount of biting is 1 mm.

Next, the operation of this embodiment will be described.
As shown in FIG. 5B, when the brake 33b is turned on under the control of the control device 40, the rotation of the cleaning roller 33a stops and “contacts” the pressure roller 20 to clean the offset toner. To do.

  As in the above “Description of the concept of the present invention”, the brake 33b is turned on for 5 seconds after the job starts, and the cleaning roller 33a “contacts” the pressure roller 20 to perform cleaning. After 5 seconds, the brake 33d is turned off, and the cleaning roller 33a rotates with the pressure roller 20 again and does not perform cleaning until the end of the job.

(4) Fourth Embodiment shaped state 6 is a diagram showing the present embodiment, (A) is a schematic structural view of a fixing cleaning device, (B) is a timing chart of the fixing cleaning device.
As shown in FIG. 6A, below the pressure roller 20, a fourth cleaning device 34 described below is disposed so as to be “slidable” on the pressure roller 20. A control device 40 is connected to the fourth cleaning device 33 and performs the following control.

  The fourth cleaning device 33 drives the cleaning roller 33a attached to the cleaning roller 33a that can be rotated with respect to the pressure roller 20 and the shaft end (not shown) of the cleaning roller 33a at a constant rotational speed. And a clutch 34b for controlling the cleaning roller drive motor 34a ON / OFF with respect to the cleaning roller 33.

Next, the operation of this embodiment will be described.
As shown in FIG. 6B, the clutch 34b is turned off and the cleaning roller drive motor 34b is turned on under the control of the control device 40. Then, since the cleaning roller 33a rotates at a speed slower than the linear speed of the pressure roller 20, the cleaning roller 33a "slids" with respect to the pressure roller 20 with a linear speed difference to clean the offset toner.
Here, the linear velocity of the cleaning roller is 165 mm / sec with respect to the linear velocity of the pressure roller of 200 mm / sec.

  As in the above “Description of the concept of the present invention”, the cleaning roller drive motor 34a is turned on for 5 seconds after the job starts, and the cleaning roller 33a “slides” with the pressure roller 20 to perform cleaning. After 5 seconds, the cleaning roller 34b rotates with the fixing roller 20 by turning on the clutch 34b, and does not perform cleaning until the end of the job.

(5) Fifth Embodiment shaped state 7 is a diagram showing the present embodiment, (A) is a schematic structural view of a fixing cleaning device, (B) is a timing chart of the fixing cleaning device.
As shown in FIG. 7A, below the pressure roller 20, a fifth cleaning device 35 described below is disposed so as to be “slidable” on the pressure roller 20. A control device 40 is connected to the fifth cleaning device 35 and performs the following control.

The fifth cleaning device 35 includes a felt cleaning roller 35a that can be rotated with respect to the pressure roller 20, a cleaning roller drive motor 34a, and a clutch 34b.
The cleaning roller 35a is a φ14 felt roller. The rotating shaft 35b of the cleaning roller 35a is pressed against the pressure roller 20 by a spring (not shown) on one side. A cleaning roller drive motor 34a for driving the cleaning roller 35a at a constant rotational speed is attached to the end portion of the cleaning roller shaft.

Next, the operation of this embodiment will be described.
As shown in FIG. 7B, the clutch 34b is turned off and the cleaning roller drive motor 34b is turned on under the control of the control device 40. Then, since the cleaning roller 35a rotates at a speed slower than the linear speed of the pressure roller 20, the cleaning roller 33a "slides" with respect to the pressure roller 20 to clean the offset toner.
Here, the linear velocity of the cleaning roller is 165 mm / sec with respect to the linear velocity of the pressure roller of 200 mm / sec.

  As in the above “Description of the concept of the present invention”, the cleaning roller drive motor 34a is turned on for 5 seconds after the job starts, and the cleaning roller 35a “slides” with the pressure roller 20 to perform cleaning. After 5 seconds, the cleaning roller 35a rotates with the fixing roller 20 when the clutch 34b is turned on, and does not perform cleaning until the end of the job.

Incidentally, the above embodiments have been described the case of a monochrome printer, the possible use of the present invention to a color printer, Ru course der.
The present invention can also be applied to a fixing roller and a pressure roller both provided with a separation claw, and a fixing roller having no separation claw and a pressure roller only. It is.
Furthermore, the present invention can be applied not only to roller fixing, but also to those using a belt on the pressure side, those using a belt on the fixing side, and those using a belt on both sides of fixing and pressing.

2A and 2B are diagrams illustrating a concept of the present invention, in which FIG. 1A is a schematic configuration diagram of a fixing unit and cleaning means (both are collectively referred to as a fixing cleaning device), and FIG. 2B is a timing chart of the fixing cleaning device. It is a schematic side view of a fixing unit used in each embodiment of the present invention. 1A and 1B are diagrams illustrating a first embodiment of the present invention, where FIG. 1A is a schematic configuration diagram of a fixing cleaning device, and FIG. 1B is a timing chart of the fixing cleaning device. 4A and 4B are diagrams illustrating a second embodiment of the present invention, in which FIG. 5A is a schematic configuration diagram of a fixing cleaning device, and FIG. 5B is a timing chart of the fixing cleaning device. 4A and 4B are diagrams illustrating a third embodiment of the present invention, in which FIG. 5A is a schematic configuration diagram of a fixing cleaning device, and FIG. 5B is a timing chart of the fixing cleaning device. 9A and 9B are diagrams illustrating a fourth embodiment of the present invention, where FIG. 9A is a schematic configuration diagram of a fixing cleaning device, and FIG. 9B is a timing chart of the fixing cleaning device. FIG. 10 is a diagram illustrating a fifth embodiment of the present invention, in which (A) is a schematic configuration diagram of a fixing cleaning device, and (B) is a timing chart of the fixing cleaning device. It is a schematic block diagram of the conventional printer.

Explanation of symbols

P transfer paper TU fixing unit 10 fixing roller 11 separation claw 20 pressure roller 30 cleaning device 40 control device 31 first cleaning device 31a cleaning blade 31b fulcrum 31c spring 31d solenoid 32 second cleaning device 32a cleaning pad 32b lever 33 first 3 cleaning device 33a cleaning roller 33b brake 34 fourth cleaning device 34a cleaning roller drive motor 34b clutch 35 fifth cleaning device 35a cleaning roller 35b rotating shaft 100 conventional printer 101 photoconductor drum 102 charging means 104 developing means 105 transfer Unit 105a Tension roller 105b Transfer roller 105c Paper transport belt 106 Drum cleaning means 10 Charge removing means 108 Rejisutoro - roller pair 109 heat fixing unit 109a heating roller 109b pressure roller 109c cleaning roller 109d separation claw 109e surface temperature detecting means

Claims (4)

In a fixing device provided with a contact type separation means for separating the transfer paper from the fixing means after fixing the toner image on the transfer paper by a fixing means and a pressure means,
The fixing unit does not include a sliding cleaning unit, and the fixing unit lowers the releasability of the transfer sheet of the pressure unit than the fixing unit; and
A roller as an offset toner cleaning means for removing offset toner adhering to the pressure means;
Control means for controlling the offset toner cleaning means,
Wherein, the short time after the start of printing, the roller rotation is stopped by contact with the pressurizing means, during printing, to perform a control to rotate with said roller to said pressure means A fixing device characterized. In a fixing device provided with a contact type separation means for separating the transfer paper from the fixing means after fixing the toner image on the transfer paper by a fixing means and a pressure means,
The fixing unit does not include a sliding cleaning unit, and the fixing unit lowers the releasability of the transfer sheet of the pressure unit than the fixing unit; and
A roller as an offset toner cleaning means for removing offset toner adhering to the pressure means;
Control means for controlling the offset toner cleaning means,
Wherein, the short time after the start of printing, the roller, with a linear velocity difference is slid on the pressing means, during printing, to perform a control to rotate with said roller to said pressure means A fixing device characterized by the above. In Fixing device according to claim 1 or claim 2 wherein,
The fixing device, wherein the roller is made of felt. An image forming apparatus comprising the fixing device as claimed in any one of claims 3.

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