JPS6343474Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fixing device for a copying machine, a printer, etc., in which a toner image on a recording paper is held between upper and lower rollers, conveyed, and fixed.

Conventionally, the toner image on the recording paper adheres to the roller and no image is formed on the recording paper, resulting in a so-called offset phenomenon, and the subsequent recording paper is smeared by the toner adhering to the roller. In order to prevent this, offset prevention liquid such as silicone oil is applied to the rollers.
However, in particular, there is a tendency for the recording paper to wrap around the upper roller, which has a built-in heater. provided. Since the anti-offset liquid is applied over the entire circumferential surface of the roller, the anti-offset liquid that is blocked by the peeling pawl and remains near the peeling pawl ends up staining the recording paper.

An object of the present invention is to provide a fixing device that prevents recording paper from being soiled by offset prevention liquid.

The present invention provides a fixing device in which recording paper having a toner image is conveyed and fixed between rollers disposed above and below that are in pressure contact with each other. A plurality of peeling claws are arranged at intervals in the axial direction of at least one of the rollers, and at least one of the peeling claws that contacts at the side and peels off the recording paper corresponds to an area other than the contact area between the at least one roller and the peeling claw. A means for applying an anti-offset liquid to the outer peripheral surface of the roller is provided, and at least one of the rollers that is downstream in the rotational direction from the peeling claw and upstream from the contact position of the upper and lower rollers is coated with the anti-offset liquid in the axial direction. This fixing device is characterized in that it is provided with a leveling member for uniformizing and leveling.

FIG. 1 is a perspective view of a heat fixing device in a copying machine according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view thereof. A heat roller 1 as an upper roller and a pressure roller 2 as a lower roller are pressed in parallel with each other and rotated in the directions of arrows 3 and 4. heat roller 1
A coating layer 6 made of a material to which toner does not easily adhere, such as Teflon (trade name), is formed on the outer periphery of a right cylindrical body 5 made of a metal with good thermal conductivity, such as aluminum, and a heater 7 is inserted therein. It consists of The pressure roller 2 is constructed of a right cylindrical body 8 made of metal such as aluminum, and a coating layer 9 made of heat-resistant rubber or the like formed on the outer periphery thereof.

Copy paper 12 as a recording paper having a toner image 11 is conveyed to a pressure contact position 10 between heat roller 1 and pressure roller 2 . The toner image 11 is melted when the heat roller 1 and the pressure roller 2 are pressed together, and the toner image 11 is melted onto the copy paper 1.
2, and fixing is performed. In order to prevent the copy paper 12 from being wrapped around the heat roller 1, a peeling claw 13 is provided downstream of the pressure contact position 10 in the rotational direction 3. A plurality of peeling claws 13 are provided at intervals in the axial direction of the heat roller 1.
The heat roller 1 is supported by a torsion spring 15 and resiliently biased against the outer circumferential surface of the heat roller 1 . One end of the torsion spring 15 is locked to the peeling claw 13, and the other end is locked to a fixed position.

Means 16 for applying an anti-offset liquid such as silicone oil to the pressure roller 2 is arranged below the pressure roller 2. An anti-offset liquid 18 is stored in a container 17 extending in the axial direction of the pressure roller 2. This anti-offset liquid 18 is applied to the support plate 34.
The coating is applied to the entire outer circumferential surface of the coating roller 20 by a holding member 19 made of a hygroscopic material such as felt, which is supported by a holding member 19 made of a hygroscopic material such as felt. The application roller 20 is fixed to a rotating shaft 21 having an axis parallel to the pressure roller 2 . The rotating shaft 21 is elastically urged toward the pressure roller 2 by a spring (not shown) so that the application roller 20 comes into even contact with the pressure roller 2, and is rotatably supported. .

FIG. 3 is a simplified front view of the thermal fixing device shown in FIGS. 1 and 2, viewed from the downstream side in the conveyance direction of the copy paper 12, that is, from the left side in FIG. The application rollers 20 are provided at intervals in the axial direction of the rotating shaft 21, and are arranged in a direction 2 in which the copy paper 12 is conveyed.
4 (upper part of the paper in Figure 3) center 25 in the left and right width direction
arranged symmetrically with respect to The anti-offset liquid applied to the pressure roller 2 is applied to the rotating heat roller 1 during a period when the copy paper 12 does not pass through the pressure contact position 10. The shaded area 23 in FIG. 3 where the anti-offset liquid is applied to the heat roller 1 corresponds to the length range of each application roller 20, and is the area where the peeling claw 13 contacts the heat roller 1. 22 in the axial direction. Therefore, the anti-offset liquid is not scraped off and retained by the peeling claw 13.

Since the area 22 where the peeling claw 13 contacts the heat roller 1 is not coated with anti-offset liquid,
As mentioned above, the offset prevention liquid does not accumulate due to the peeling claw. Therefore, the copy paper that is wrapped around the heat roller 1 and whose leading edge comes into contact with the peeling claw 13 will not be stained by the anti-offset liquid.

A leveling member 27 is provided downstream of the peeling claw 13 of the heat roller 1 in the rotational direction 3 and upstream of the contact position 10 between the heat roller 1 and the pressure roller 2 . The leveling member 27 includes a contact piece 28 made of a material such as rubber that extends over the entire length of the heat roller 1 in the axial direction, and a support member 29 that brings the contact piece 28 into elastic contact with the heat roller 1. . A contact position 30 between the contact piece 28 and the heat roller 1 is located downstream of a vertical line 31 passing through the axis of the heat roller 1 in the rotation direction 3 . Therefore, the excess anti-offset liquid dammed up by the contact piece 28 is removed by the reference numeral 32.
It can be stored as shown in .

The anti-offset liquid applied by the application roller 20 adheres to the upper roller 1 from the lower roller 2, and as shown in FIG.
By storing a large amount of the liquid, the anti-offset liquid is applied to the downstream side of the leveling member 27 over the entire circumferential surface of the heat roller 1 in a uniform thickness. In this way, the toner image on the copy paper 12 is prevented from adhering to the heat roller 1. Although the anti-offset liquid adheres to the area including the contact area 22 other than the application area 23 via the contact position 10, the amount is very small, so the amount stored by the peeling claw 13 is small. . Therefore, staining of the copy paper is prevented.

FIG. 5 is a perspective view of a portion of another embodiment of the present invention, and FIG. 6 is a cross-sectional view of the embodiment. The same reference numerals are used for corresponding parts of the previously described embodiments. In this embodiment, an application roller 20a is in contact with the pressure roller 2 over its entire axial length. The holding member 19a applies the anti-offset liquid in the container 17 to the application roller 20a. The holding member 19a has notches 35 corresponding to the plurality of peeling claws 13 that contact the heat roller 1 at intervals in the axial direction to prevent the anti-offset liquid from being applied to the contact area 22 thereof. This notch 35 creates a region on the application roller 20a and the pressure roller 2 where the anti-offset liquid is not applied, so that the anti-offset liquid is not stored by the peeling claw 13. The other configurations are similar to those of the previous embodiment.

Fig. 7 is a cross-sectional view of yet another embodiment of the present invention. This embodiment is similar to the embodiment of Fig. 5 and Fig. 6, but it is noteworthy that the application roller 20a in Fig. 5 and Fig. 6 is omitted, and the holding member 19a is brought into elastic contact with the pressure roller 2.

The present invention can be implemented not only in copiers, but also in connection with printers and the like. The present invention can also be implemented in connection with a so-called pressure fixing device that does not have a heater 7 and performs fixing only by pressure contact force.

As described above, according to the present invention, since the anti-offset liquid is not applied to the portion corresponding to the peeling pawl, the leading edge of the recording paper that comes into contact with the peeling pawl is not stained by the anti-offset liquid.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of one embodiment of the present invention, FIG. 2 is a cross-sectional view of the first embodiment, and FIG.
FIG. 4 is a simplified front view of the heat fixing device of the embodiment shown in FIG. FIG. 6 is a cross-sectional view of the embodiment shown in FIG. 5, and FIG. 7 is a cross-sectional view of still another embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Heat roller, 2... Pressure roller, 12... Copy paper, 13... Peeling nail, 16... Application means, 1
9, 19a... Holding member, 20, 20a... Application roller.

Claims (1)

[Claims for Utility Model Registration] In a fixing device in which recording paper having a toner image is conveyed and fixed between rollers disposed above and in pressure contact with each other, at least one of the rollers is provided with a pressure contact position of the upper and lower rollers. A plurality of peeling claws are arranged at intervals in the axial direction of at least one of the rollers, and the peeling claws that come into contact with each other on the downstream side in the rotational direction to peel off the recording paper are arranged at intervals in the axial direction of at least one roller, and at least in an area other than the contact area between at least one of the rollers and the peeling claw. Means for applying an offset prevention liquid to the outer peripheral surface of at least one of the corresponding rollers is provided, and at least one of the rollers downstream of the peeling claw in the rotational direction and upstream of the contact position of the upper and lower rollers is provided with an offset prevention liquid. A fixing device comprising a leveling member for uniformizing and leveling a liquid in an axial direction.