JP2013029575A - Fixing device and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fixing device and an image forming apparatus which are capable of reducing offset toner left behind due to a difference of toner physical properties, and which are capable of outputting an image free from image staining due to offset toner.SOLUTION: A fixing device 20 comprises: a fixing belt 23 which is heated by a heating roller 21; a pressure roller 24 which is pressure-welded by the fixing belt 23; and cleaning means 30 which feeds a cleaning web 31 to a surface of the pressure roller 24 and cleans the surface. The fixing device 20 includes a temperature sensor 38 for detecting a surface temperature of the pressure roller 24 and a web motor control part 37 for controlling a feeding amount of the cleaning web 31. The web motor control part 37 determines the feeding amount of the cleaning web 31 of the cleaning means 30, on the basis of toner information stored in an ID chip of toner cartridge.

Description

  The present invention relates to a fixing device and an image forming apparatus.

  In an image forming apparatus using an electrophotographic technique, as a technique used for fixing means for fixing a toner image to a transfer material such as paper, a heating roller incorporating a heat source such as a halogen lamp, which is an example of a fixing rotator, A so-called thermocompression bonding, in which a transfer material carrying a toner image is passed through a nip formed by a pressure roller that rotates while being in pressure contact with the heating roller, which is an example of a pressure rotating body, and the toner image is fixed to the transfer material. The method is widely adopted. In this type of fixing technology, the transfer material carrying the toner image by the pressure roller is pressed against the heating roller with a predetermined pressure, and thus is heated by the heating roller and becomes a molten state. It is desirable that all of the melted toner is fixed on the transfer material, but in reality, only a small part of the melted toner adheres to the heating roller due to the adhesion between the toner and the heating roller. In general, this phenomenon is called an offset phenomenon.

  The types of offset phenomenon include a low temperature offset and a high temperature offset. Low temperature offset means that the toner is not sufficiently heated and the heat is not sufficiently transferred to the inside of the toner layer forming the toner image, so that the toner is not completely melted and fused to the transfer material. A part of the toner layer is crushed and adhered to the heating roller. In this case, since the toner image is not sufficiently fused to the transfer material, a so-called fixing failure occurs in which the toner image can be easily scraped from the output copy. High temperature offset means that when the toner is heated at an unnecessarily high temperature, the viscoelasticity of the toner changes and the adhesion between the toner and the heating roller becomes higher than the cohesion of the toner particles, and the toner adheres to the heating roller. It is.

  On the other hand, for copy images output by an electrophotographic image forming apparatus, there is an increasing demand for higher image quality. In order to ensure the print quality equivalent to the offset image, the trend is to reduce the diameter of the toner or make it spherical like a polymerized toner. For this reason, compared to conventional toners, heat is not easily transmitted to the toner, and the melting is not sufficient, so that there has been a problem that low temperature offset is likely to occur. In particular, it tends to occur when the surface of the paper is uneven, such as uncoated paper.

  As a countermeasure to this problem, as described in Patent Document 1 and the like, a fixing cleaning means that presses a cleaning web such as a non-woven fabric on the heating roller with a pressing roller, and always wipes the surface of the rotating heating roller. It is generally performed. However, spherical and small-diameter toner tends to pass through a small gap formed between the cleaning web and the heating roller, and in order to prevent this, a new portion of the cleaning web to which no toner is attached is always heated or pressed. It is necessary to prevent the gap from being generated as much as possible by pressing the roller. However, it is not desirable to supply a cleaning web having a sufficient area each time a copy is output from the viewpoint of increasing the maintenance frequency of the image forming apparatus or increasing waste from an environmental viewpoint.

  In view of this problem, Patent Document 2 proposes a cleaning unit that can prevent unnecessary web supply by controlling the supply amount of the cleaning web based on image data. In Patent Document 2, as the web feed amount increases as the image data (= toner image area / image area) increases, the feed amount is increased, and slipping from the web paper is less likely to occur.

  Recently, for example, as described in Patent Document 3, a mechanism has been developed in which a cleaning member is not disposed on the fixing roller side (image surface side) but a cleaning web is disposed on the pressure side. This is because when the cleaning web is added to the image surface side, the roller or belt surface side is damaged, and an abnormal image such as a vertical stripe is generated. However, when a cleaning member is added to the pressure surface side, the degree of penetration of the offset toner changes depending on the toner start-off temperature, which is a physical property of the toner, so that the optimum feeding amount of the cleaning web changes. For example, when the pressure roller temperature is lowered by passing paper, it becomes difficult for the web to penetrate into the web, and slippage from the web is likely to occur. On the other hand, there is a circumstance that the pressure roller temperature cannot be so high from the viewpoint of print quality (toner blister or the like). The above-described toner flow-out start temperature measuring apparatus uses a flow tester that evaluates the flow characteristics of a flowable material such as resin from the relationship of temperature, pressure, and flow velocity. The toner blister occurs when a toner image is formed on the coated paper, and expands when air (and moisture) in the gap between the toner and the gap between the toner and the recording medium is fixed. The coated paper side has a poor air permeability, so there is no escape space for the thermally expanded gas. As a result, bubbles are generated in the toner layer, and the fixed image is disturbed.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a fixing device and an image forming apparatus capable of solving the above-described conventional problems, reducing the amount of offset toner remaining due to the difference in toner physical properties, and outputting an image free from image smear due to the offset toner. Yes.

  In order to achieve the above object, the present invention provides a fixing rotator heated by a heating means, a pressure rotator pressed against the fixing rotator, and a cleaning web delivered to the surface of the pressure rotator. The transfer material carrying the unfixed toner image is passed through the nip between the fixing rotator and the pressure rotator so that the unfixed toner image is formed by the action of heat and pressure. In the fixing device fixed to the transfer material, the fixing device includes a control unit that controls a feeding amount of the cleaning web of the cleaning unit, and the control unit feeds the cleaning web of the cleaning unit based on toner information to be used. The fixing device is characterized in that it is determined.

  According to the present invention, the feed amount of the cleaning web for removing the toner adhering to the belt or the roller due to the offset is controlled according to the offset toner amount by controlling the web feed amount based on the information of the toner to be used. As a result, the web can be fed by an appropriate amount, a stable print quality can be secured over time, and the life of the cleaning web can be extended.

1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment of the present invention. 1 is a schematic diagram illustrating a fixing device of the present invention. FIG. 5 is a schematic diagram illustrating an operation mechanism for winding of a fixing cleaning unit. 3 is a control flow of the image forming apparatus according to the embodiment of the present invention. 6 is a table showing a relationship between a pressure roller temperature and toner adhesion. 6 is a table showing an example of a web control table of a fixing device. 10 is a table showing another example of a web control table of the fixing device. 10 is a table showing still another example of the web control table of the fixing device. It is a table | surface of the coefficient applied to the web feed amount for every transfer material.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a schematic cross-sectional view illustrating an example of an image forming apparatus. The image forming apparatus shown here includes a plurality of image carriers 2Y, 2C, 2M, and 2K made of a drum-shaped photoconductor, and an intermediate transfer belt 3 made up of an endless belt in contact with the peripheral surface of these image carriers. have. The intermediate transfer belt 3 is wound around support rollers 4, 5, 6, guided by a guide roller 8, and rotationally driven in the direction of arrow A by a drive motor (not shown). On the other hand, the image carriers 2Y to 2K are also driven to rotate counterclockwise in FIG. 1 by a motor (not shown).

  In each of the image carriers 2Y to 2K, toner images of different colors are formed. In the illustrated example, a yellow toner image, a cyan toner image, a magenta toner image, and a black toner image are formed on the image carriers 2Y to 2K. It is formed. The toner image formed on the surface of each image carrier is transferred to the surface of the intermediate transfer belt 3.

  The configuration for forming a toner image on each image carrier 2Y, 2C, 2M, 2K and transferring the toner image to the intermediate transfer belt 3 is substantially the same except that the color of the toner image is different. Therefore, only a configuration in which a toner image is formed on one of the image carriers 2Y and the toner image is transferred to the intermediate transfer belt 3 will be described. As shown in FIG. 1, image forming means for forming a toner image on the surface of the image carrier 2Y is provided around the image carrier 2Y. The image carrier 2Y is counterclockwise in FIG. When rotated in the direction, the image carrier 2Y is charged to a predetermined polarity by a charging device including a charging roller 7 to which a charging voltage is applied. The charged image carrier 2Y is irradiated with a light-modulated laser beam L emitted from an optical writing device (not shown), whereby an electrostatic latent image is formed on the image carrier 2Y. This electrostatic latent image is visualized as a yellow toner image by the developing device 9.

  A primary transfer device composed of a transfer roller 10 is disposed on the opposite side of the intermediate transfer belt 3 from the image carrier 2Y, and a transfer voltage is applied to the transfer roller 10 to form the image carrier 2Y. The toner image is transferred onto the intermediate transfer belt 3 that rotates in the arrow A direction. The transfer residual toner adhering to the image carrier 2Y after the toner image transfer is removed by the cleaning device 11.

  In exactly the same manner as described above, a cyan toner image, a magenta toner image, and a black toner image are respectively formed on the image carriers 2C, 2M, and 2K shown in FIG. 1, and these toner images are transferred to the yellow toner image. Then, the toner images are sequentially transferred onto the intermediate transfer belt 3, and a composite toner image is formed on the intermediate transfer belt 3. The transfer residual toner on each of the image carriers 2C, 2M, 2K after the toner image transfer is removed by the cleaning device is the same as in the case of the first image carrier 2Y.

  On the other hand, a support roller 6 positioned at the lowermost of the support rollers around which the intermediate transfer belt 3 is wound is provided with a transfer roller 16 as an example of a secondary transfer device with the intermediate transfer belt 3 interposed therebetween. A transfer material P made of, for example, paper or a resin sheet is fed between the transfer roller 16 and the intermediate transfer belt portion wound around the support roller 6 as indicated by an arrow. At this time, a predetermined transfer voltage is applied to the transfer roller 16, whereby the composite toner image on the intermediate transfer belt 3 is transferred onto the transfer material P. Instead of the transfer roller 16, a transfer device such as a transfer belt, a transfer brush, or a corona discharger can be used. Either type of transfer device is used to transfer the toner image transferred to the intermediate transfer belt 3 to the transfer material P. The transfer material P onto which the toner image has been transferred is further conveyed leftward in FIG. 1 and passes through the fixing device 20.

FIG. 2 is a schematic configuration diagram illustrating a configuration of the fixing device 20.
In FIG. 2, the fixing device 20 is a belt fixing system, and a fixing belt 23 wound around a heating roller 21 and a fixing roller 22 as a fixing rotating body, and pressure applied to the fixing roller via the fixing belt 23. And a pressure roller 24 as a rotating body. The fixing roller 22, the pressure roller 24, and the heating roller 21 are rotatably supported in the longitudinal direction of a casing (not shown) of the fixing device 20, and are each rotated in the direction of an arrow by a driving unit (not shown). Various heating methods of the heating roller 21 can be applied. In this example, the heating roller 21 is heated by the heater lamp 25 disposed in the hollow.

  The fixing belt 23 is an endless belt formed of a PI layer having a thickness of 90 μm, and has an outer peripheral surface coated with an offset preventing agent such as a PFA film. The fixing roller 22 and the pressure roller 24 are rubber rollers arranged to face each other. When the pressure roller 24 is pressed toward the center of the fixing roller 22 via the fixing belt 23, the pressure roller 24. And a fixing belt 23 form a nip portion. Reference numeral 26 denotes a tension roller that applies tension to the fixing belt 23, and is formed of a cylindrical aluminum tube. The pressure roller 24 can be depressurized to the fixing roller 22 by a depressurization mechanism (not shown). Reference numeral 27 denotes a heater lamp disposed in the hollow of the pressure roller 24.

  The driving unit includes a motor and a reduction gear train, and is gear-connected to the fixing roller 22. When the driving unit is rotationally driven in the arrow direction shown in FIG. 2, the fixing roller 22 rotates in the arrow direction. As the fixing roller 22 rotates, the pressure roller 24 and the fixing belt 23 that are in pressure contact with the fixing roller 22 rotate in the direction of the arrow at the same speed.

  Heat from the heater lamp 25 disposed in the hollow of the heating roller 21 is transmitted to the fixing belt 23 through the heating roller 21, and the fixing belt 23 is heated. By the reverse rotation of the pressure roller 24 and the fixing belt 23, the transfer material P is conveyed while the toner image T is heated and melted at the nip portion.

  In the fixing device having the above-described configuration, the transfer material P on which the toner image is formed is conveyed in the arrow direction shown in FIG. 1 from the pre-fixing guide 28 disposed on the upstream side of the fixing belt 23 in the transfer material conveyance direction. The toner image of the transfer material is fixed by heating and melting at the nip portion. Thereafter, the transfer material P is separated from the fixing belt 23 by the separation plate 29 after the exit of the nip, and discharged to the transfer material discharge portion (not shown) by the conveyance roller 17 arranged on the downstream side in the transfer material conveyance direction. Is done. A paper discharge sensor 18 is disposed at the fixing outlet in order to confirm that the transfer material has passed at a predetermined timing.

  The fixing device 20 is provided with a fixing cleaning means 30. The fixing cleaning means 30 includes a cleaning web 31 in which an aromatic polyamide non-woven fabric is impregnated with silicone oil as a release agent, a supply roller 32 winding a new web, a take-up roller 33 for collecting a used web, foaming It consists of a pressure roller 34 made of silicon resin. A predetermined amount of the cleaning web 31 wound around the winding roller 33 is fed by a web motor 36 described later, and a winding operation is performed with a constant torque. The pressing roller 34 presses the cleaning web 31 against the pressure roller 24 by a support member (not shown) and a pressing spring (not shown). A 3 to 6 mm cleaning nip is formed between the cleaning web 31 and the pressure roller 24 by this pressing, and the toner T adhering to the surface of the pressure roller 24 due to the offset rotates the pressure roller 24 in the direction of the arrow. As a result, the cleaning web 31 is wiped by the cleaning nip.

  FIG. 3 is a schematic diagram for explaining a winding operation mechanism of the fixing cleaning unit 30. The feed amount of the cleaning web 31 is determined by the rotation amount of the take-up roller 33. The take-up roller 33 has a reduction gear 35 attached to a rotation shaft installed in parallel with the take-up roller 33, and rotates by the rotation of a web motor 36 constituted by a step motor via the reduction gear 35. In the present embodiment, the gear reduction ratio is set so that the cleaning web 31 is fed by 0.82 mm by one step rotation of the web motor 36. The web motor 36 is fed by a motor control unit 37 so that a new web is sent out by intermittent control in which the motor operates once for a predetermined number of sheets.

  In the fixing device 20 of the present embodiment, the feed amount of the cleaning web 31 is changed by changing the time for operating the web motor 36 (hereinafter referred to as the web motor operation time). The motor operation interval is 15 sec (cycle).

Next, FIG. 4 shows a control flow of the image forming apparatus having the fixing device 20 described above.
Information on toner used for image formation is input to the control unit of the fixing device 20. As the best method for obtaining the toner information, information on an ID chip 40 provided in a toner container such as a toner cartridge (not shown) is used. In addition to storing the remaining amount of toner stored in the ID chip 40, the manufacturing lot information of the toner manufacture, and toner information confirmed at the time of toner manufacture, for example, toner outflow start temperature as the physical property information of the toner are stored. It is remembered. In this embodiment, the feed amount of the cleaning web 31 is controlled based on this information. When the toner flow start temperature is high, the toner offset with respect to the cleaning web 31 is not sufficiently melted, so that it adheres to the surface of the pressure roller 24 again and adheres to the sheet as toner fixing. FIG. 5 shows the relationship between the toner outflow start temperature and toner fixation. To prevent toner sticking due to slipping from the cleaning web 31, toner sticking is prevented by extending the operation time of the web motor 36. The toner flow start temperature can be measured by the flow tester (CFT-500D / 100D) described above.

  In the fixing device having the above-described configuration, as is apparent from FIG. 5, a large amount of slipping occurs when the toner outflow start temperature is 110 ° C. or higher. In order to prevent this, the web motor operation time is controlled to increase as the temperature rises based on the toner outflow start temperature. If the toner starts flowing out temperature, 110 ° C. or higher in this example, the offset toner does not penetrate into the cleaning web 31 (it stays on the paper as toner particles), so that a slip-through phenomenon from the cleaning web 31 is likely to occur. End up. For this reason, by setting the web motor operating time longer, it is possible to control so that the offset toner does not adhere to the transfer material again. Specifically, based on information in the ID chip 40 at the time of toner replacement, a necessary web feed amount is calculated from the web control table storage unit 38 based on the web control table shown in FIG. 6, and based on the calculated value, The web motor control unit 37 operates the web motor 36 for a desired operation time, and in the fixing device of this example, the sheet is always controlled as described above during sheet passing.

  Further, in the web control table shown in FIG. 6, in addition to the toner outflow start temperature, the winding time of the motor is changed between the single-sided printing and the double-sided printing in the image forming mode. In the case of duplex printing, in addition to offset to the belt side, offset to the pressure side also increases the amount of input to the cleaning web 31. For this reason, in the web control table shown in FIG. 6, in addition to controlling the toner outflow start temperature, the amount of winding of the cleaning web 31 at the time of double-sided printing is changed to be larger than that at the time of single-sided printing.

  By the way, in the image forming apparatus in which the paper interval during paper passing changes depending on the paper size of the transfer material P to pass paper, the amount of toner offset to the cleaning web 31 changes when the paper interval during paper passing changes. It is preferable to control the winding amount of the cleaning web 31 according to the P paper size.

  Therefore, in the present fixing device 20, the web control table shown in FIG. 7 shows the winding amount of the cleaning web 31 according to the toner outflow start temperature stored in the ID chip 40 of the toner cartridge and the paper size of the transfer material P. Control based on In the case of a transfer material having a paper size where the toner start-off temperature is equal to or higher than a certain temperature and the paper interval is wide, the slipping-off from the cleaning web 31 can be suppressed by increasing the winding time of the cleaning web 31. it can.

  As described above, based on the toner physical property information stored in the ID chip 40 in the toner cartridge, the paper feed amount of the cleaning web 31 is changed depending on the paper size of the transfer material to pass, so that any paper size In this case, the web can be fed by an appropriate amount according to the amount of offset toner, so that stable print quality can be secured over time, and the life of the cleaning web can be extended.

  By the way, when the transfer material P to be passed is coated paper, the offset amount with respect to the cleaning web 31 is smaller than that of uncoated paper. This is presumably because the coated paper has a smooth surface compared to the uncoated paper, so that heat is easily transmitted to the toner and the offset amount is small.

  Therefore, in the fixing device of the present embodiment, the web motor operation time is set to be shorter in the case of the coated paper as compared to the uncoated paper. Specifically, when the transfer material P is coated paper and uncoated paper, the winding time of the cleaning web 31 is set as shown in the web control table shown in FIG. As a result, it is possible to maintain a state where there is no slip-through from the cleaning web 31.

  In this way, stable print quality is maintained by changing the feed amount of the cleaning web 31 between coated paper and non-coated paper based on the information of the toner outflow start temperature stored in the ID chip 40 of the toner cartridge. be able to.

  Further, in the fixing device 20, an optimum feed amount is grasped in advance for each transfer material P used by the user and stored in the control unit. A value obtained by multiplying the optimum web feed amount by a certain coefficient based on the information of the toner outflow start temperature is controlled as the web feed amount. Thus, by controlling the optimum feed amount for each paper type, it is possible to maintain a high-quality image without slipping over time. FIG. 9 shows a web feed amount table of coefficients to be applied to the toner outflow start temperature with respect to the optimum web feed amount. A web feed amount reference table preset for each transfer material used in this manner is stored in the memory of the control means, and further, the feed amount of the cleaning web 31 is controlled by the information on the toner outflow start temperature. Even for such a transfer material, an optimal web feed amount is always ensured, and a stable image can be output.

As mentioned above, although preferable embodiment of this invention was described, this invention is not limited only to the said embodiment, Various modifications can be made.
For example, although the belt fixing type fixing device 20 has been described, the fixing device 20 may be a roller fixing type, and therefore the fixing rotator may be a fixing roller. Further, the pressure rotating body is not limited to the pressure roller, and the present invention can also be applied to a fixing device using a pressure belt.

DESCRIPTION OF SYMBOLS 20 Fixing device 21 Heating roller 22 Fixing roller 23 Fixing belt 24 Pressure roller 30 Fixing cleaning means 31 Cleaning web 32 Supply roller 33 Winding roller 36 Web motor 37 Web motor control part 40 ID chip

JP 2002-258657 A JP-A-2005-024619 JP 2008-04-0053 A

Claims (10)

A fixing rotator that is heated by a heating unit; a pressure rotator that is pressed against the fixing rotator; and a cleaning unit that sends a cleaning web to the surface of the pressure rotator to clean the surface. In a fixing device in which an unfixed toner image is fixed to a transfer material by the action of heat and pressure by passing a nip between a fixing rotator and a pressure rotator through a transfer material carrying a toner image.
Control means for controlling the amount of cleaning web delivered by the cleaning means;
The fixing device determines the feeding amount of the cleaning web of the cleaning device based on toner information to be used.   The fixing device according to claim 1, wherein the toner information is toner physical property information stored in an ID chip provided in a toner cartridge containing toner to be used.   The fixing device according to claim 2, wherein the toner physical property information is a toner outflow start temperature.   4. The fixing device according to claim 1, wherein the control unit changes a feeding amount of the cleaning web between single-sided printing and double-sided printing. 5.   5. The fixing device according to claim 4, wherein the control unit changes the double-sided printing so that the amount of feeding of the cleaning web is longer than that during single-sided printing.   6. The fixing device according to claim 4, wherein the control unit changes a feeding amount of the cleaning web between single-sided printing and double-sided printing.   The fixing device according to claim 1, wherein the control unit changes the feeding amount of the cleaning web according to a paper size to pass the paper.   The fixing device according to claim 1, wherein the control unit changes a feeding amount of the cleaning web between coated paper and uncoated paper.   9. The fixing device according to claim 1, wherein the memory of the control means has a reference table of a cleaning web feed amount preset for each sheet to be passed.   An image forming apparatus comprising the fixing device according to claim 1.

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