JPH11167304A - Cleaning device for fixing roller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To keep the performance of a cleaning member without cleaning even in the case of long time printing, and to obtain a high quality print by switching the rotating direction of a cleaning brush with respect to a heat roller to forward rotation and reverse rotation in accordance with the thickness of a printing paper. SOLUTION: The cleaning brush 4 is attached to a fixing part as a heat roller cleaning mechanism. The brush 4 switches the rotating direction to the heat roller 2 to forward and reverse in accordance with the thickness of the printing paper. That is, the brush 4 is constituted to reversely rotate with respect to the rotation of the roller 2 by a printer main body side driving gear 23. The switching from the reverse rotation to the forward rotation can be performed by moving a lever 13 to the thin paper side of a rectangular hole 14 of a brush holder 5, so that a gear 11 becomes in a free condition by being disengaged from the gear 15, the gear 11 rotates with the roller 2 and the forward rotation can be performed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electrophotographic recording apparatus, and more particularly, to a fixing roller cleaning apparatus.

[0002]

2. Description of the Related Art A fixing section of an electrophotographic apparatus is composed of a pair of rollers. The fixing section fixes a toner transferred onto a sheet by the heat and pressure of the rollers while nipping and conveying the sheet between the rollers. The pair of rollers includes a heat roller and a backup roller. Generally, a heat roller covers or coats the surface of a metal cylinder with PFA or the like, which has good release properties, and has a heater inside. A backup roller covers the surface of cylindrical silicon rubber with PFA or the like. I have. In a fixing unit of an electrophotographic apparatus, a so-called unfixed toner remaining without being fixed by printing adheres to a heat roller and causes a reduction in print quality. Many.

As an example of a cleaning mechanism, there is a cleaning brush system which is inexpensive and saves space. The cleaning brush system includes a roller-shaped member having a brush on the outer peripheral surface thereof, which is brought into contact with the surface of the heat roller, and is rotated forward or backward with respect to the rotation of the heat roller to wipe off unfixed toner. Some recent cleaning brush systems have a function of applying silicone oil to improve the releasability of toner on the surface of the heat roller and prevent surface damage.

In the case of a fixing method using heat and pressure, thick paper is more likely to deprive the heat of the surface of the heat roller than thin paper. The amount of toner increases.
When the amount of toner remaining on the heat roller increases, the amount of toner adhering to the surface of the cleaning brush also increases, and toner particles often peel off from the surface of the rotating cleaning brush onto the printing surface, thereby lowering print quality.
For the above reason, the printing quality of the thick paper is much lower than that of the thin paper, and the thickness of the printing paper affects the life of the cleaning brush.

The rotation direction of the cleaning brush is
It is common to fix to either forward rotation or reverse rotation. If the cleaning brush rotates in reverse,
Cleanability of unfixed toner is good, but life is easy to shorten because a large amount of toner adheres to the surface of the cleaning brush.When the cleaning brush rotates forward, cleaning performance of unfixed toner is lower than reverse rotation. However, the service life is characterized by the direction of rotation, such as extending from reverse rotation.

[0006]

When printing is performed for a long time by an electrophotographic apparatus, toner adheres and accumulates on the surface of the cleaning brush, so that the cleaning property is deteriorated and the adhered toner damages the surface of the heat roller. . Further, the cleaning brush method having a function of applying silicon oil causes a large decrease in print quality, such as an inability to appropriately apply oil to the surface of the heat roller. For this reason, conventionally, the entire fixing unit is replaced in accordance with the life of the cleaning brush, or only the cleaning brush is replaced within a relatively short period of time.

An object of the present invention is to extend the life of a cleaning member. And, by extending the life of the cleaning member, an inexpensive product can be provided to the customer.

It is another object of the present invention to provide a high quality printed matter while maintaining the original performance of the cleaning member even during long-time printing.

[0009]

An object of the present invention is to provide a fixing roller cleaning apparatus for rotating a cleaning member in contact with the surface of a heat roller to wipe off unfixed toner. Is achieved by providing means for switching between forward rotation and reverse rotation depending on the thickness of the printing paper.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described with reference to the drawings. FIG. 3 is an explanatory diagram of the internal structure of the fixing unit in the electrophotographic apparatus.

When the transferred paper 1 is conveyed to the fixing section, it passes between the heat roller 2 and the backup roller 3, and the toner on the paper 1 is fixed by the heat transmitted from the heat roller 2. Since the toner on the sheet 1 is not completely fixed, a very small amount of unfixed toner remains on the surface of the heat roller 2. In order to wipe off toner adhered to the surface of the heat roller 2, a cleaning brush 4 is added to the fixing unit as a heat roller cleaning mechanism.

The cleaning brush 4 is a roller-shaped member having a pile length of 2 to 4 mm and a brush mainly made of PPS on the outer peripheral surface, and is brought into contact with the surface of the heat roller 2.
The heat roller 2 is rotated in the reverse direction to wipe off and clean the unfixed toner.

When printing is performed for a long time, toner adheres and accumulates on the surface of the cleaning brush 4, and the cleaning property of the heat roller 2 deteriorates.
Failure to scratch the surface occurs. In order to prevent such a problem, the cleaning brush 4 is provided with a rotation direction switching mechanism.

FIG. 4 is a perspective view when a cleaning brush rotation direction switching mechanism is added to the fixing unit. The cleaning brush 4 is detachable and can be replaced periodically. More specifically, the cleaning brush 4 is attached to the brush holder 5, and the fixing is performed by inserting the U grooves 8 (two locations) of the brush holder 5 into the pins 7 (two locations) of the fixing unit main body 6. The attachment of the brush holder 5 to the main body 6 is completed.

FIG. 1 is an explanatory view of the cleaning brush rotating direction switching mechanism, and shows a state in which the cleaning brush 4 moves backward. Both ends of the cleaning brush 4 are metal shafts 9
And both ends of the shaft 9 are provided with a sleeve bearing 10
And is supported by the brush holder 5. In order to rotate the cleaning brush 4, the driving side of the shaft 9 is D
A gear 11 that is cut and D-cut at the center is assembled on the shaft 9, and an E-ring 12 is added to the drive-side end of the shaft 9 to prevent the gear 11 from coming off. The gear 11 can move left and right on a D-cut portion of the shaft 9. Gear 11 is lever 13
The gear 15 is provided so as to mesh with the gear 11.

A bearing holder 20 is fixed to the fixing unit body frame 21 with screws 22, sleeve bearings 19 are mounted on both ends of a center hole of the bearing holder 20, and a gear 16 having a metal shaft 17 as a center is attached to the fixing unit body frame 21. It is attached outside. Metal shaft 17
Has a D-cut portion, and a gear 15
Are attached via an E-ring 18.

The gear 16 is connected to a drive gear 23 on the printer main body side, and the cleaning brush 4 can be rotated by the drive gear 23 on the printer main body in a direction reverse to the rotation of the heat roller 2.

The thickness is less than 90 kg paper or 104 g.
When printing less than / m ² paper (thin paper), the amount of unfixed toner is smaller than when printing thick paper, so that the cleaning brush 4 can be rotated with respect to the heat roller 2 in order to extend the life. It is like that.

FIG. 2 is an explanatory view in the case where the cleaning brush 4 performs a forward rotation. The switching from the reverse rotation to the forward rotation is performed by moving the lever 13 to the “thin paper side” of the square hole 14 of the brush holder 5 so that the lever 13
The gear 11 is disengaged from the gear 15 while being supported by the cleaning brush 4 and the power from the printer body side gear 23 is not transmitted to the cleaning brush 4.
Becomes free with respect to the rotation direction and rotates together with the heat roller 2, so that forward rotation is possible.

As described above, according to this embodiment, the switching between the forward rotation and the reverse rotation of the cleaning brush 4 is performed by moving the lever 13 to the thick paper / thin paper side along the square hole 14 of the brush holder 5. By switching, the gear 11,
This is performed depending on whether the gear 15 is engaged. The cleaning brush 4 can be moved forward and backward by reversing the direction of rotation of the printer body side drive gear 23.

[0021]

According to the present invention, a long life of the cleaning member can be realized, and a long life of the cleaning member can provide an inexpensive product to the customer. Further, the original performance of the cleaning member can be maintained even in long-time printing, and a high-quality printed matter can be provided.

[Brief description of the drawings]

FIG. 1A is a longitudinal sectional view of a cleaning brush rotation direction switching mechanism (in a case of selecting a thick paper side) according to an embodiment of the present invention, and FIG. 1B is a plan view of FIG.

FIG. 2A is a longitudinal sectional view of a cleaning brush rotation direction switching mechanism (in the case of selecting a thin paper side) according to an embodiment, and FIG.
2 is a plan view of FIG.

FIG. 3 is an explanatory diagram of an internal structure of a fixing unit.

FIG. 4 is a perspective view when a cleaning brush rotation direction switching mechanism of the embodiment is added to a fixing unit.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Paper, 2 ... Heat roller, 3 ... Backup roller, 4 ... Cleaning brush, 5 ... Brush holder, 6 ...
Fixing unit body, 7 ... pin, 8 ... U groove, 9 ... shaft, 10
... Sleeve bearing, 11 ... Gear, 12 ... E-ring,
13 ... lever, 14 ... square hole, 15 ... gear, 16 ... gear,
17: shaft, 18: E-ring, 19: sleeve bearing, 20: bearing holder, 21: fixing unit body frame, 22: screw, 23: printer body side drive gear.

Claims (3)

[Claims] In a fixing roller cleaning device for rotating a cleaning member in contact with the surface of a heat roller to wipe off unfixed toner, the direction of rotation of the cleaning member with respect to the heat roller is changed according to the thickness of printing paper. An apparatus for cleaning a fixing roller, comprising: means for switching between dynamic rotation and reverse rotation. 2. A fixing roller cleaning apparatus for rotating a cleaning member in contact with a surface of a heat roller to wipe off unfixed toner, wherein the direction of rotation of the cleaning member with respect to the heat roller is set to 90 kg paper thickness of printing paper. Or more than 104 g / m ² paper (thick paper) and thickness 9
A fixing roller cleaning mechanism, comprising: means for selectively switching between a sheet of paper less than 0 kg and a sheet of paper less than 104 g / m ² (thin paper). 3. A fixing roller cleaning device for rotating a cleaning member in contact with a surface of a heat roller to wipe off unfixed toner, wherein the direction of rotation of the cleaning member with respect to the heat roller is set to 90 kg paper thickness of printing paper. A means for switching to reverse rotation when the paper is more than or 104 g / m ² paper (thick paper), and switching to forward rotation when the paper is less than 90 kg thick or less than 104 g / m ² (thin paper). Fixing roller cleaning device.