JP2006259341A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent the occurrence of glossy stripes when forming an image, by removing paper powder deposited on an outside area of a sheet size having a high frequency in use. <P>SOLUTION: In a fixing device including fixing members (40, 50, and 60) for fixing toner on a recording medium and a pressure member (70) which is brought into contact with the fixing members to form a nip where the recording medium passes, a rotating cleaning member (80) is brought into contact with surfaces of the fixing members, and an auxiliary cleaning member (90) is brought into contact with ranges corresponding to a prescribed paper passage size on the surfaces of the fixing members from inside to the outside. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a fixing device and an image forming apparatus. More specifically, the present invention relates to a point of cleaning paper dust in a portion protruding from a sheet passing size of a fixing member in a configuration for fixing an unfixed image on a recording medium. is there.

JP 2000-305393 A JP 2003-21980 A JP 2003-122185 A

  In an image forming apparatus such as a copying machine, a printer, or a facsimile, an unfixed image transferred and carried on a sheet-like recording medium such as paper (hereinafter referred to as a sheet) is heated and fixed to copy or record the recorded material. obtain. As a fixing device that performs heat fixing processing, a configuration in which rollers are pressed against each other or a configuration in which a roller and a belt are combined is known. In the configuration using a belt, in place of a roller positioned on the side facing an unfixed image in a fixing device that performs fixing using pressure contact between rollers, a belt stretched between a pair of rollers is not fixed. Arranged so as to face the image, one of the pair of rollers is opposed to a pressure roller that presses the sheet. Among the rollers around which the belt is stretched, the roller facing the pressure roller is a fixing roller, and the rollers other than the fixing roller are heating rollers incorporating a heat source for heating the belt. The basic configuration of such a belt fixing device is disclosed in Patent Document 1, Patent Document 2, and Patent Document 3, for example.

  Since the fixing belt is driven by the slip force of the internal roller, there is a drawback in that smooth rotation of the belt is hindered when a cleaning member or the like is strongly pressed against the belt. Since the heat capacity can be reduced by reducing the temperature, the temperature can be increased in a short time, and there is an advantage that the temperature rise at the time of start-up is faster than in the case where the rollers are nipped and fixed. It is also advantageous for temperature followability (characteristic that the fixing member surface temperature recovers after dropping).

  And, the fixing belt used in such a belt fixing device has a surface coated with a fluororesin for improving releasability, but when rotating in a state of being stretched between the fixing roller and the heating roller, The belt shape bends during rotation. Therefore, the fluororesin on the surface layer does not follow the bending and easily breaks, so that an additive for increasing the hardness cannot be used.

  If the continuous belt is continuously passed through the narrow belt using the fixing belt, the paper dust generated from the side of the size width will come out of the size width on the belt surface. Therefore, there is no phenomenon such as “the paper dust is removed by the next sheet”, and the paper dust is embedded and deposited in the fluororesin layer not containing the additive of the fixing belt. Since the surface of the fixing belt on which paper dust is deposited is different from other belt surface portions, there is a possibility that gloss streaks are generated in a solid image or the like. A normal cleaning roller, for example, a cleaning roller (hollow roller, cleaning roller) disclosed in Patent Document 1 or Patent Document 2 or a cleaning belt disclosed in Patent Document 3 rotates in accordance with the rotation of the fixing belt. It is difficult to completely remove paper dust. Such a problem can also occur in the problem of roller fixing in which the hardness is lowered in order to widen the nip portion.

  In view of these problems, the present invention has an object to prevent the occurrence of glossy streaks during image formation by removing paper dust that accumulates on the outer area of a frequently used sheet size. is there.

  According to the present invention, there is provided a fixing device comprising: a fixing member that fixes toner on a recording medium; and a pressure member that forms a nip that contacts the fixing member and through which the recording medium passes. This is solved by abutting the rotating cleaning body on the surface of the fixing member and further contacting the auxiliary cleaning member from the inside to the outside of the range corresponding to the predetermined sheet passing size on the surface of the fixing member.

It is preferable that the auxiliary cleaning member has a fluororesin at a portion that contacts the fixing member. It is convenient if the pressure at which the auxiliary cleaning member comes into contact with the fixing member is 10 mN / mm ² or less. The ridgeline where the auxiliary cleaning member comes into contact with the fixing member is more preferably inclined with respect to the direction in which the fixing member rotates so that the inside of the auxiliary cleaning member comes into contact with the downstream position rather than the outside. It is. It is convenient if the auxiliary cleaning member can be removed, or the auxiliary cleaning member can be moved in the width direction of the fixing member. In the case of a so-called belt fixing device, it is preferable that the belt contact surface of the auxiliary cleaning member has a fluororesin, and the pressure at which the auxiliary cleaning member contacts the fixing belt is 10 mN per unit width of the auxiliary cleaning member. / Mm or less is convenient. It is more preferable that the belt contact ridge line of the auxiliary cleaning member is inclined with respect to the rotation direction of the fixing belt so that the inner side of the member is in contact with the downstream position rather than the outer side. It is effective if the auxiliary cleaning member can be removed or moved in the width direction of the fixing belt.

  According to the present invention, in addition to the cleaning roller for the entire sheet passing range, there is provided an auxiliary cleaning member that contacts and rubs the fixing member in a specific range from the inside to the outside of the frequently used sheet size. The accumulated paper dust outside the sheet size is scraped off from the fixing member, and the auxiliary cleaning member also contacts the inner side of the sheet size width. Occurrence can be prevented.

  By coating the surface of the auxiliary cleaning member with the fluororesin on the surface that comes into contact with the fixing member, it becomes difficult for the toner to adhere to the auxiliary cleaning member due to the property of the fluororesin having good releasability. The fixing member can be prevented from being damaged.

By adjusting the pressure of the auxiliary cleaning member in contact with the fixing member to 10 mN / mm ² or less, foreign matters and toner that have been once pinched pass through quickly, so that the fixing member can be prevented from being damaged by foreign matters and toner.

  If the ridge line of the auxiliary cleaning member that contacts the fixing member is slanted so that the inner side contacts the downstream side of the outer side than the outer side with respect to the fixing member rotation direction, the paper dust from the side of the sheet size width is sized. Even if the paper dust comes out of the width, the paper dust moves along the oblique ridge line into the paper passing area, and the next sheet removes the paper dust, so that the paper dust can be prevented from being accumulated on the fixing member. .

  By making the auxiliary cleaning member detachable from the bracket, etc., it is not necessary to attach the auxiliary cleaning member to an unnecessary position, and if it is desired to use at that size, it is only necessary to move it and attach the auxiliary cleaning member. Can be

The details of the present invention will be described below based on the example shown in the drawings.
First, an example applied to a laser printer (hereinafter referred to as a printer) which is an electrophotographic image forming apparatus will be described. FIG. 1 shows a schematic overall configuration of the printer. This printer has a photosensitive drum 1 as a latent image carrier. The surface of the photosensitive drum 1 is uniformly charged by a charging roller 2 as charging means that contacts the drum 1 while being driven to rotate in the direction of arrow A in the figure. Thereafter, scanning exposure is performed by the optical writing unit 3 as a latent image forming unit based on the image information, and an electrostatic latent image is formed on the drum surface. As the charging unit and the latent image forming unit, those different from the charging roller 2 and the optical writing unit 3 can be used. The electrostatic latent image formed on the photosensitive drum is developed by the developing device 4, and a toner image is formed on the photosensitive drum. The toner image formed on the photosensitive drum is a sheet as a recording medium conveyed from a paper feed cassette 6 through a paper feed roller 7 and a resist roller pair 8 by a transfer unit as a transfer means having a transfer roller 5. 9 is transferred. After the transfer, the toner image is fixed on the sheet 9 by the fixing device 10 and is discharged to the outside space 12 via the paper discharge roller 11. A paper discharge tray 13 for stacking and storing sheets 9 is disposed in the external space 12. The untransferred toner remaining on the photosensitive drum without being transferred is removed from the surface of the photosensitive drum 1 by a cleaning unit 14 as a cleaning unit. Residual charges on the photosensitive drum are removed by a static elimination lamp 15 as a static elimination means.

  As shown in FIG. 2, the fixing device 10 is in pressure contact with the fixing roller 50, the heating roller 60, the fixing belt 40 wound around these rollers, and the fixing belt 40 through the fixing belt 40 in an unillustrated device casing. The pressure roller 70 is arranged. The fixing roller 50 incorporates a heat source (hereinafter referred to as a heater) 55 and is covered with a rubber 50a having a fluororesin / rubber on the surface layer. The heating roller 60 is made of a metal pipe having heaters 65 and 66 therein. The fixing belt 40 is configured by stacking silicone rubber on a base material of a metal film (for example, Ni, SUS, etc.) or a resin film (for example, PI, PAI) and a fluororesin on the surface layer. The fixing belt 40 is driven and rotated by the fixing roller 50, but may be driven and rotated by the heating roller 60. As with the fixing roller 50, the pressure roller 70 that rotates in contact with the fixing roller 50 with the fixing belt 40 interposed therebetween has a heater 75 therein and is covered with a rubber 70a having a fluororesin on the surface layer.

  The heaters 55, 65, 66, 75 in the respective rollers 50, 60, 70 detect the temperatures of the fixing belt 40 and the pressure roller 70 by temperature sensors 53, 63, 73 arranged in the vicinity of the respective rollers. The lighting is controlled by doing. However, a plurality of temperature sensors 53 for the fixing roller 50 exist in the longitudinal direction of the fixing roller 50 and detect the temperatures at the center and the end in the sheet passing area.

  In the belt fixing device 10 configured as described above, the sheet to which the toner corresponding to the image information is attached is formed by the pressure contact deformation of the rubber layer 50a of the fixing roller 50 and the rubber layer 70a of the pressure roller 70. When passing through the nip portion, heat and pressure are obtained by the fixing belt 40 heated by the fixing roller 50 and the heating roller 60 and further by the pressure roller 70 to fix the toner. The toner remaining on the fixing belt 40 is cleaned by a cleaning roller 80 that is in contact with the fixing belt 40 on the side opposite to the pressure roller 70. Paper dust is generated from the sheet to be passed, and this is also generally removed by the cleaning roller 80. However, since the cleaning roller 80 rotates in accordance with the fixing belt 40, the paper dust is completely removed only by this cleaning roller. It is difficult to do. In particular, when continuous sheet feeding of narrow sheets is continued, paper dust generated from the side of the sheet size width comes out on the belt surface outside the sheet size width and does not contain additives for increasing the hardness. There is a possibility that the fixing belt is buried and deposited in the fluororesin layer. A rubbing cleaning member 90 as an auxiliary cleaning member for cleaning such paper dust, particularly paper dust that can accumulate in the vicinity of a portion corresponding to a side edge of a sheet of a predetermined size on the surface of the fixing belt is in contact with the fixing belt 40. Is provided.

  As shown in FIG. 3, the rubbing cleaning member 90 has a predetermined range in the width direction of the fixing belt 40, in the illustrated example, a range from the inner side to the outer side of the B4 vertical size sheet and an inner side to the outer side of the A4 vertical size sheet. A total of four are arranged in this range, abut against the fixing belt 40, and rub against the belt 40 by rotation of the fixing belt 40. The arrangement position of the rubbing cleaning member is determined so as to contact the fixing belt 40 in a range from the inside to the outside of the frequently used sheet size. In general, the A4 vertical, A4 horizontal, B4 vertical, B5 horizontal, and B5 vertical sizes are rubbed so that they are within the range from the inside to the outside of the side edge of the frequently used sheet according to the individual usage environment. A cleaning member 90 is installed. By this rubbing cleaning member 90, paper dust outside the sheet size is scraped off from the fixing belt 40, and the rubbing cleaning member 90 also rubs against the fixing belt 40 even inside the sheet size width. The change in the difference is also dull, and the occurrence of gloss streaks can be suppressed.

  As shown in FIG. 4, the rubbing cleaning member 90 may cover the base material 90 a with a fluororesin and abut the fluororesin layer 90 b on the fixing belt 40. If there is a small amount of paper dust and a large amount of offset toner remains on the fixing belt 40, if the toner adheres to the rubbing cleaning member 90, the adhered toner cools and hardens when the power is turned off. If the fixing belt 40 resumes rotation in such a state, the fixing belt 40 may be damaged as a side effect. By using the fluororesin layer 90b as a rubbing surface, it is difficult for toner to adhere, the belt can be prevented from being scratched, and side-effect gloss streaks can also be prevented.

  When the sliding cleaning member 90 comes into contact with the fixing belt 40, if the contact pressure becomes too strong, the fluororesin on the belt surface is easily damaged. Therefore, a contact pressure adjusting mechanism as shown in FIG. 5 may be added. That is, a leaf spring 91 is attached to the bracket 100 to hold the rubbing cleaning member 90 'rotatably at the fulcrum 90C. A spring 92 that holds the rubbing cleaning member 90 ′ against the fixing belt 40 is also held. At this time, if the contact pressure is increased, the fluororesin on the surface layer of the fixing belt 40 is easily damaged, and gloss streaks are generated as a side effect of the rubbing cleaning member 90. Therefore, the pressure is adjusted to 10 mN / mm or less per width 90d (FIG. 3) of the rubbing cleaning member 90 'that contacts the fixing belt 40. As a result, even if foreign matter or toner is once caught between the fixing belt 40, the foreign matter or toner can easily pass through the rubbing portion, and the belt 40 can be prevented from being scratched. Occurrence can also be prevented. In FIG. 5, the same members as those in FIG. 2 are given the same reference numerals, and the description thereof is omitted.

  In FIG. 3, the rubbing cleaning member 90 is in contact with the fixing belt 40 at a right angle. However, as shown in FIG. 6, the ridge line of the rubbing cleaning member 90 contacting the belt 40 is on the inner side with respect to the rotation direction of the belt 40. It may be slanted so that it may come back and contact. By making the ridge line oblique in this way, paper dust moves along the ridge line into the paper passing area, and the next sheet can remove the paper powder.

  Furthermore, a case where a B4 size sheet or the like is not passed depending on the use state of the machine is also assumed. In such a case, as can be understood from FIG. 6, if the holding leaf spring 91 can be removed and moved out of the sheet passing area 100 a of the bracket 100, the rubbing cleaning member 90 is placed at an unnecessary position. In addition, when there is a need to use a sheet of that size, the attachment position is moved, so that unnecessary rubbing in the effective area of the fixing belt 40 is eliminated.

1 is a schematic configuration diagram of a laser printer which is an image forming apparatus according to the present invention. 1 is a schematic configuration diagram of a main part of a fixing device according to the present invention. FIG. 6 is a diagram illustrating an arrangement position of a cleaning roller and a rubbing cleaning member viewed in the width direction of the fixing belt. It is the schematic which shows that the belt contact surface of a rubbing cleaning member is given the fluororesin. FIG. 6 is a schematic configuration diagram of a main part of another fixing device according to the present invention. It is a figure which shows that a rubbing cleaning member is removable from a bracket. FIG. 6 is a view showing that the belt contact ridge line of the rubbing cleaning member is inclined so as to be drawn downstream.

Explanation of symbols

40 fixing belt 50 fixing roller 50a rubber layer 53 temperature sensor 55 heater 60 heating roller 63 temperature sensor 65, 66 heater 70 pressure roller 70a rubber layer 73 temperature sensor 75 heater 80 cleaning roller 90 rubbing cleaning member

Claims (8)

In a fixing device comprising: a fixing member that fixes toner on a recording medium; and a pressure member that forms a nip that contacts the fixing member and through which the recording medium passes.
A rotary cleaning body contacts the surface of the fixing member,
Further, the auxiliary cleaning member contacts from the inside to the outside of a range corresponding to a predetermined sheet passing size on the surface of the fixing member.   The fixing device according to claim 1, wherein the fixing member includes a tension belt provided with a heat source and a pressure roller in contact with the tension belt.   2. The fixing device according to claim 1, wherein the auxiliary cleaning member has a fluororesin at a portion in contact with the fixing member. The fixing device according to claim 1, wherein a pressure at which the auxiliary cleaning member contacts the fixing member is 10 mN / mm ² or less.   The ridgeline where the auxiliary cleaning member comes into contact with the fixing member is inclined with respect to the direction in which the fixing member rotates so that the inside of the auxiliary cleaning member comes into contact with the downstream position from the outside. The fixing device according to claim 1.   The fixing device according to claim 1, wherein the auxiliary cleaning member is removable.   The fixing device according to claim 1, wherein the auxiliary cleaning member is movable in a width direction of the fixing member.   An image forming apparatus comprising the fixing device according to claim 1.

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