JPH0247682A - Fixing device - Google Patents

Abstract

PURPOSE:To prevent toner from being offset at a place corresponding to a contact member by providing a releasing agent supply means which supplies a releasing agent more to the outer peripheral surface of a pressure roller corresponding to the contact member than to other outer peripheral surfaces. CONSTITUTION:When a heat roller 1 and the pressure roller 2 rotate, the releasing agent supply means 7 coats the outer peripheral surface of the pressure roller 2 with the releasing agent 10. Namely, the releasing agent supply means 7 supplies the releasing agent directly to the outer peripheral surface 2a of the pressure roller 2 and the releasing agent 10 is stored in a pipe 8. Oil similar to silicone oil with which a paper web 6a is impregnated is used as the releasing agent 10. Therefore, the releasing agent 10 is applied more to the part corresponding to the slide contact part of the contact member 4 than any other outer peripheral surface. Consequently, the rest toner is prevented from remaining on the contact member 4 which comes into slide contact with the outer peripheral surface of the pressure roller 2 to prevent copying paper S from being stained, the maintenance is facilitated, and the cost for copying is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a fixing device that is incorporated into a toner transfer type image forming device such as an electrophotographic copying machine or a laser beam printer and fixes transferred toner on a sheet. .

2. Description of the Related Art In general, in image forming apparatuses such as electrophotographic copying machines and printers, toner transferred onto copy paper is fixed by heating while applying pressure. As shown in FIG. 9, this type of fixing device includes a heating roller (20) with a built-in heater (25), and a pressure roller (22) that presses against the heating roller (20) with a predetermined pressure. Those with the following are common. A paper web type cleaning device (28) is usually installed on the heating roller (20> side).This cleaning device (28) is designed to prevent mold release agents such as silicone oil from seeping into the cloth material. This paper web (28a) is
8a) is brought into sliding contact with the outer circumferential surface (20a) of the heating roller (20), and the dirt on the outer circumferential surface (20a) is wiped off. Also, both rollers (20).

(22) are provided with separation claws (26) and (27), respectively, to prevent the copy paper (S) from wrapping around the roller.

By the way, the toner (T) transferred to the copy paper (S) is
The copy paper (S) that can be conveyed in the direction of arrow (A) is
0) and (22), it is melted and fixed by heating and pressure. And when this takes hold,
Usually, a portion of the toner (T) is offset to the outer peripheral surface (20a) of the heating port (20) and becomes residual toner (T1). This remaining toner (T1) is removed by the cleaning device (28
), but if the copy density is high, the paper web (28a)
A small amount of residual toner (T2) is not completely wiped off.
and is transferred from the heating roller (20) side to the pressure roller (22) side at the nip portion.

This is because the outer circumferential surface (22a) of the pressure roller (22) has poorer toner releasability than the outer circumferential surface (20a) of the heating roller (20). That is, the heating roller (20)
The paper web (28a) has completely applied oil to the outer peripheral surface (20a) of the pressure roller (22).
This is because oil as a mold release agent is not applied to the outer peripheral surface (22a) of the mold.

By the way, the remaining toner (T2) transferred to the pressure roller (22) side will be offset to the back side of the next copy sheet. Normally, this residual toner (T2) is so small that even if it is offset to the back side of the copy paper, it cannot be seen with the naked eye, and it hardly causes any substantial problems as image noise.

However, the outer peripheral surface (
22a), there was a problem that the transferred residual toner (T2) accumulated, so to speak, and was offset, staining the back surface. That is, in the separating claw (27) on the pressure roller (22) side, the remaining toner (T2) is accumulated little by little at the tip as the pressure roller (22) rotates.

When the staying toner (T3) collected in this way has accumulated to a certain extent, it separates from the tip of the separating claw (27) when the pressure roller (22) starts rotating from a stopped state, and the staying toner (T3) separates from the tip of the separation claw (27), leaving the outer peripheral surface (22a ).

When the copy paper passes through the nip, this staying toner (T3) is offset to the back surface of the copy paper, causing stains on the back surface of the copy paper, and appears as image noise from the front surface of the copy paper.

In order to avoid the above problems, it is conceivable to apply a mold release agent to the pressure roller (22) side as well. For example, a plurality of small holes are bored in the peripheral wall of the pipe, the surface of the vibrator is covered with felt, etc., and a release agent application roller containing silicone oil is placed around the outer circumference of the pressure roller (22). Attempts have been made to bring the surface (22a) into sliding contact with the surface (22a) so that it can be driven and rotated.

Problems to be Solved by the Invention However, this type of applicator roller has a pressure roller (2
2) The oil is applied uniformly to the entire outer circumferential surface, which is undesirable in terms of running costs and maintenance. That is, it is necessary to apply the release agent at least to the part where the tip of the separating claw (27) contacts, and to prevent the remaining toner (T2) from dislocating to the heating roller (22) side in this part. Just prevent it. However,
On the outer peripheral surface (22a) of the pressure roller (22), the same amount of mold release agent is applied to the part where the separation claw (27) comes into sliding contact and the outer peripheral surface which does not require as much mold release agent. , the amount of mold release agent supplied is inevitably large. For this reason, it was necessary to replace the application roller early. Therefore, the frequency of maintenance increases, which is undesirable in terms of maintenance and management, and the amount of oil used increases more than necessary, resulting in problems such as an increase in the overall cost of copying.

In addition, the same problem occurs in that residual toner remains at the tip of the separating claw (26) that slides on the outer circumferential surface (20a) of the heating roller (20), and the thermal sensor for temperature control is attached to the outer circumferential surface ( A similar problem occurs when it is installed in sliding contact with 20a).

SUMMARY OF THE INVENTION An object of the present invention is to prevent residual toner from remaining on a contact member that slides on at least one of the rollers on the outer circumferential surface of the heating roller or the pressure roller, and to prevent stains on copy paper. To provide a fixing device that is easy to maintain and has low copying costs.

Means and Effects for Solving the Problems In order to solve the above problems, the present invention provides: (a) a heating roller equipped with a heat source; (b) a pressure roller that presses against the heating roller; (C)
a contact member slidingly in contact with the outer peripheral surface of at least either the pressure roller or the heating roller; and (d) more release agent on the outer peripheral surface of the pressure roller corresponding to at least the contact member than on the other outer peripheral surfaces. In the above structure, when the heating roller and the pressure roller rotate, a release agent is supplied from the release agent supply means to the outer circumferential surface of the pressure roller. agent is applied. The release agent can be applied directly to the pressure roller, or first applied to the heating roller and then applied to the pressure roller as both rollers rotate. In either form, in the heating roller and the pressure roller, more release agent is applied to the portion corresponding to the sliding contact portion of the contact member than to the other outer peripheral surfaces. Therefore, toner offset itself from the copy paper onto the outer circumferential surface of the heating roller can be prevented as much as possible, and even if the toner is offset from the heating roller, transfer to the pressure roller can be prevented, and as a result, the toner can be prevented from sliding onto the surface of the sheet. No accumulation on sliding contacts.

Embodiments Hereinafter, embodiments of a fixing device according to the present invention will be described with reference to the accompanying drawings.

[First Example 1. 1 and 2 The fixing device of the first embodiment includes a heating roller (1), a pressure roller (2) that is in pressure contact with the heating roller (1), and a pressure roller (2) disposed on the heating roller (1) side. A cleaning device (6) provided therein and a release agent supplying means (7) provided on the pressure roller (2) side.
), and separation claws <3) and <4).

The heating roller (1) has a built-in heater (5) as a heat source, and is adjusted to a predetermined temperature by on/off control of the heater (5) based on a temperature signal from a thermal sensor (not shown). The toner (T) on the copy paper (S) conveyed from the side is heated. Pressure roller (
2) is pressed against the heating roller (1) by a pressure mechanism consisting of a spring means (not shown), and the rollers (1), (2)
The toner (T) on the copy paper (S) passing through the nip section is pressurized. The toner (T) on the copy paper (S) is fixed by heating and pressure when passing through this nip. The heating roller (1) has a core metal whose outer peripheral surface is coated with Teflon, and the pressure roller (2) has a core metal whose outer peripheral surface is coated with an elastic material such as silicone rubber, and the outer peripheral surface of which is coated with Teflon. The tube is coated, and the material itself improves the releasability of the toner to prevent toner offset as much as possible.

The separation claws (3) and (4) are used to prevent the copy paper (S) from wrapping around the roller, and the tip end is attached to the roller (
The outer peripheral surfaces (t) of (1) and (2) are in sliding contact with (2) at a predetermined pressure. And these separation claws (3) and (4) are
A plurality of rollers are arranged at predetermined intervals in the axial direction of each roller (1), <2).

The cleaning device (6) is of a well-known paper web type and sequentially winds up a paper web (6a) wound around a roller (6c) with a roller (6b). This paper web (6a) is pre-impregnated with a release agent such as silicone oil, is prevented from loosening by a spring plate (6d), and is slid onto the heating roller (1) by a pressure roller (6e). A mold release agent is supplied to the outer circumferential surface (Ia) and the outer circumferential surface (18) is cleaned.

The mold release agent supply means (7> is for directly supplying the mold release agent to the outer peripheral surface (2a) of the pressure roller (2), and the mold release agent (10) is contained in the vibrator (8). is accommodated.

As the mold release agent (10), the paper web (6a)
An oil similar to the silicone oil impregnated with is used. The vibrator (8>) is made of an aluminum cylindrical body, has a plurality of exudation holes (8a) on the peripheral wall, and has holes on the outer peripheral surface.
An oil-permeable layer (9) is formed. The seepage hole (8a) is
A suitable number of small holes are formed at positions corresponding to the separation claws 4) at predetermined intervals in the circumferential direction. Oil-soluble M (9') C. It is formed by coating the surface of the vibrator (8>) with an elastic body such as felt material. 2a), and when the entire supply means (7) rotates in accordance with the rotation of the pressure roller (2), it retains the release agent leaking from the seepage hole (8a) and pressurizes it. The outer peripheral surface (2) of the roller (2)
In a), a larger amount of mold release agent is applied to the area where the separating claw (4) comes into sliding contact than the other outer peripheral surfaces, and the entire outer peripheral surface (2a) is also cleaned.

In the above configuration, when the heating roller (1) and the pressure roller (2) rotate, the entire supply means (7) is driven to rotate, and the oil permeable layer (9) is transferred from the outer peripheral surface (2a) of the pressure roller (2).
) can be completely coated with mold release agent. Then, the copy paper (S) on which the toner image has been transferred is conveyed in the direction of the arrow (A) and passes through the nip between the rollers (1) and (2), so that the toner is deposited onto the copy paper (S). (T) is fixed. At this time,
A portion of the toner (T) is attached to the outer circumferential surface (1a) of the heating roller (1).
) and become the remaining toner. This residual toner is wiped off by a cleaning device (6), but it remains partially when the copy density is high, as in the conventional fixing device. This remaining toner is removed from the roller (1).
, (2) comes into contact with the pressure roller (2) at the nip part, but
On the outer circumferential surface (2a) of this pressure roller (2), a release agent is applied by the release agent supply means (7), so that
It does not transfer to the outer peripheral surface (28) of the pressure roller (2). However, if residual toner is transferred to the outer peripheral surface (2a) of the pressure roller (2), it is only the separation claws (4
) is the sliding contact point. Therefore, in the first embodiment, the mold release agent is supplied exclusively to the area where the tip of the separation claw (4) comes into sliding contact.
It was designed to prevent toner transfer. Of course, the pressure roller (
The release agent applied to 2) is also transferred to the heating roller (1) side, and the toner (T) is transferred to the outer peripheral surface (1a) of the heating roller (1).
It is also necessary to prevent offset itself as much as possible.

[Second Embodiment, Fig. 3] In this second embodiment, a trace amount is added to the pipe (8) of the supply means (7) at a location other than the exudation hole (8a) and the location corresponding to the separation claw (4). A seepage hole (8b) is provided. That is,
The minute seepage holes (8b) had smaller diameters than the above-mentioned seepage holes (8a), and were arranged between the seepage holes (8a) in the axial direction. Note that the other configurations are the same as those of the first embodiment.

According to the above configuration, the outer peripheral surface (2a) of the pressure roller (2)
, the outer peripheral surface other than the part corresponding to the separation claw (4) (
A small amount of mold release agent (10) can also be applied to 2a). Therefore,
The outer circumferential surface (2a) of the pressure roller (2) has improved releasability, which further reduces residual toner transferred to the pressure roller (2) side, making it possible to further remove stains from the copy paper (S). Become.

[Third Embodiment, Figure 4] In this third embodiment, in addition to the exudation hole (8a) corresponding to the separation claw (4), the vibrator (8) of the supply means (7) has a replenishment exudation hole. (8c) is provided. That is, the supplementary seepage holes (8c) had approximately the same diameter as the seepage holes (8a), and were arranged in fewer numbers than the seepage holes (8a) between the seepage holes (8a) in the axial direction. Note that the other configurations are the same as those of the first embodiment.

As a result, the amount of release agent supplied to the pressure roller (2) is
This is equivalent to the case where the minute seepage hole (8b) is provided as in the second embodiment, and the same effect can be obtained.

[Fourth Embodiment, FIG. 5] In this fourth embodiment, the cleaning device (6) is omitted from the fixing device shown as the first embodiment.

Regarding the mold release agent supply means (7), the same one as shown in the first embodiment is used, but in the second and third embodiments.
Those shown in the examples may be used.

[Fifth Embodiment, FIG. 6] This fifth embodiment is a fixing device shown as the first embodiment, in which a cleaning device (6) and a pressure roller (
The separation claw (4) on the side 2) is omitted. That is, there is a possibility that toner remains at the tip of the separation claw (3) even in the heating roller (1). On the other hand, the release agent supplied from the supply means (7) to the pressure roller (2) is supplied to the heating roller (1).
) and improves its releasability. Therefore, in a configuration like the fifth embodiment, the toner (
The offset prevention effect of T) itself to the heating roller (1) prevents toner from staying at the contact portion of the separating claw (3>).

Regarding the mold release agent supply means (7), the same one as shown in the first embodiment is used, but the one shown in the second and third embodiments may also be used. .

[Sixth Embodiment, Figure 7] In this sixth embodiment, in the fixing device shown as the fifth embodiment, the release agent supplying means (7) is replaced with the heating roller (1).
It is placed on the side. In the case of the sixth embodiment, on the outer peripheral surface (1a) of the heating roller (1), the separating claw (3)
More release agent is directly applied to the area corresponding to the area than the other outer peripheral surface (1a). Therefore, the purpose here is to prevent the toner from staying at the tip of the separating claw (3), as in the fifth embodiment, and to prevent the toner (T) on the copy paper (S).
The effect of preventing offset to the heating roller (1) is further enhanced.

Of course, as for the mold release agent supply means (7), the one shown in the first embodiment, or the one shown in the second or third embodiment may be used.

[Seventh Embodiment, FIG. 8] In the fixing device of the seventh embodiment, a release agent supply means (11) is composed of a tank (12) and a coating member (13). The tank (12) is arranged below the pressure roller (2) and stores silicone oil as a mold release agent (10). The coating member (13) is made of a plate-shaped felt material or the like, and its lower end is immersed in the release agent (10) in the tank (12), and its upper end has a convex coating piece (13a).
are formed in multiple numbers. This application piece (13a) is formed at a location corresponding to the separation claw (4) that slides on the pressure roller (2), and slides on the outer peripheral surface (2a) of the pressure roller (2).

According to the above configuration, the mold release agent (10
) is from the application piece (13a) to the outer peripheral surface of the pressure roller (2) (
2a), and the same effects as in the first embodiment are achieved.

The applicator member (13) also has the seepage hole (8b) shown in the second and third embodiments between the applicator pieces (13a).

A small application piece having the same function as (8C) may be formed.

[Other Embodiments] Note that the fixing device according to the present invention is not limited to the above embodiments, and can be variously modified within the scope of the gist.

In particular, there is a risk that toner may accumulate not only at the contact point of the separation claw but also at the contact point of the thermal sensor (not shown), so the supply point of the mold release agent should correspond to the contact point of the thermal sensor. It's okay.

Effects of the Invention As detailed above, according to the present invention, in a fixing device equipped with a contact member that makes sliding contact with at least one of the heating roller and the pressure roller, the outer peripheral surface of the roller corresponding to the contact member is provided with a Since a release agent supply means is provided to supply more release agent than the outer peripheral surface of the contact member, it is possible to prevent toner from offsetting to the area corresponding to the contact member as much as possible. This eliminates the problem of offset to the back side of the copy paper, and prevents the copy paper from becoming stained. In addition, the mold release agent is
It is sufficient to supply at least a portion of the outer circumferential surface of the roller corresponding to the contact member, and the amount used is smaller than when it is evenly supplied to the entire outer circumferential surface. Therefore, the deterioration of the release agent supplying means is reduced, the service life is long, maintenance is easy, and the fixing device as a whole has excellent economic efficiency.

[Brief explanation of the drawing]

1 to 8 show respective embodiments of the fixing device according to the present invention, FIG. 1 is a cross-sectional view of the first embodiment, and FIG. 2 is a cross-sectional view of the first embodiment.
FIG. 3 is a perspective view of the main part of the second embodiment, FIG. 4 is a perspective view of the main part of the third embodiment, FIG. 5 is a cross-sectional view of the fourth embodiment, and FIG. The figure is a cross-sectional view of the fifth embodiment, FIG. 7 is a cross-sectional view of the sixth embodiment, and FIG. 8 is a longitudinal cross-sectional view of the seventh embodiment. FIG. 9 is a cross-sectional view showing a conventional fixing device. (1)...heating roller, (2)...pressure roller, (
la). (2a)...outer peripheral surface, (3), (4)...separation claw, (7)...mold release agent supply means, (8)...vibrator, (8a), (8b), (8c) - seepage hole, (9)
...Oil purifying layer, (10)...Mold release agent, (11)...
・Release agent supply means, <12)...Tank, (13)・
...Coating parts.

Claims (1)

[Scope of Claims] 1. A heating roller equipped with a heat source; a pressure roller in pressure contact with the heating roller; a contact member in sliding contact with the outer peripheral surface of at least either the pressure roller or the heating roller; A fixing device comprising: a release agent supply means for supplying more release agent to the outer peripheral surface of the pressure roller corresponding to the contact member than to other peripheral surfaces.