JPH1020698A - Fixing device - Google Patents

Abstract

(57) [Summary] To provide a fixing device capable of collecting a surplus liquid while preventing liquid leakage. SOLUTION: When a coating unit 10 is mounted on a main body unit 1, an intermediate roller 4 abuts on a felt 13,
A gap d occurs in the tank opening 15 due to the elastic deformation of the leaf spring 14. As a result, the surplus oil regulated by the blade 5 is recovered into the tank 11 from the gap d. On the other hand, when the coating unit is a single unit, the leaf spring 14 pushes up the felt 13 to bring the tip of the felt into contact with the tank ceiling portion 11b and close the tank opening 15.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device for an image forming apparatus, and more particularly, to a fixing device having an application unit for applying an offset preventing liquid to a fixing roller.

[0002]

2. Description of the Related Art An unfixed image (an image formed by a toner made of a heat-fusible resin or the like) mounted on an image forming apparatus such as a copying machine, a printer, or a facsimile and transferred onto a recording medium such as a transfer sheet. A fixing roller (heating roller) and a pressure roller are pressed into contact with each other, and the recording medium is passed between the two rollers to generate heat and pressure on the recording medium. A thermal fixing device of a type for fixing an unfixed toner image is well known.

In such a fixing apparatus, a small amount of an anti-offset liquid (silicone oil or the like) is applied to the fixing roller to prevent the toner from being offset from the recording medium to the fixing roller. It is common practice to improve the moldability. Conventionally, when a mechanism for supplying the anti-offset liquid to the fixing roller is provided separately from the fixing device, a tank for storing the anti-offset oil, a pump for circulating the oil, a coating member, and the amount of oil are regulated. A collecting member, a tray, and the like for collecting oil from the regulating member are required, and the number of components is increased, and a large space for disposing them is also required.

For this reason, there has been proposed a device in which the offset preventing liquid supply mechanism is unitized and provided as a unit that can be integrated with or integrated with the fixing device. For example, JP-A-6-83227, JP-A-55
Japanese Patent Application Laid-Open No. 7-7995 and Japanese Patent Application Laid-Open No. 4-257885 each include a tank filled with an offset preventing liquid, and a supply member provided in the tank and supplying the fixing roller or the intermediate roller with the offset preventing liquid. A coating unit (fixing device including the coating unit) is shown.

The coating unit described in these publications is disposed below the fixing roller, has a function of recovering excess oil (anti-offset liquid) from the fixing roller or the intermediate roller, and stores the anti-offset liquid. Since the unit has a function for supplying the offset prevention liquid to the fixing roller or the intermediate roller in the unit, there is an advantage that the number of components is reduced.

[0006]

However, the above-mentioned Japanese Patent Application Laid-Open No. 6-83227 and Japanese Patent Application Laid-Open No. 55-779
In the case of the apparatus described in Japanese Patent Application Laid-Open No. 5 (1999) -1995, the upper part of the oil tank is largely open when the application unit is mounted on the fixing device, and the tank is tilted or shaken when moving the main unit. , There is a problem that the anti-offset liquid leaks.

In the apparatus described in Japanese Patent Application Laid-Open No. Hei 4-257885, a lid for sealing the upper surface of the tank is provided, so that excess oil from the fixing roller or the intermediate roller cannot be collected in the tank. However, there is a problem that excess oil accumulates on the lid.

Further, when a cloth-like oil application / supply member such as an application felt is arranged in a tank, the tank is often provided in a thin and long shape. In such a configuration, when the main unit is installed inclined with respect to the longitudinal direction of the tank, the liquid is shifted, and the liquid level detection sensor is provided even though the offset prevention liquid remains in the tank. However, there is a problem that the liquid may be erroneously detected as running out of liquid. When the remaining amount of the liquid is small, the coating / supplying member may not be able to sufficiently suck up the liquid.

SUMMARY OF THE INVENTION It is an object of the present invention to solve the above-mentioned problems in a fixing device having a conventional coating unit, and to provide a fixing device which can recover excess liquid while preventing liquid leakage.

[0010]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides a fixing roller, a pressure roller, and an offset preventing device which is provided so as to be integrally mounted on an apparatus body. A fixing unit having an application unit for applying the liquid, the application unit includes a tank for storing the anti-offset liquid, and the anti-offset liquid in the tank is partially immersed in the anti-offset liquid and the fixing unit or the intermediate member. A supply member for supplying the offset prevention liquid to the fixing roller, and a pressing unit for pressing the supply member against the fixing roller or the intermediate member, wherein the coating unit is not integrally mounted on the apparatus main body. When the supply member closes the opening of the tank by the pressing force of the pressurizing means and the application unit is integrally attached to the apparatus main body, the supply Member proposes to move to open the opening of the tank by being pressed against the fixing roller or the intermediate member.

The coating unit is disposed below the fixing roller or the intermediate member, and an upper surface of the tank is formed in a concave shape in which a ceiling portion is dropped downward and a periphery is surrounded by a side wall. An opening of the tank is provided on the ceiling of the upper surface, the amount of application is regulated by the regulating member, the excess liquid falling from the fixing roller or the intermediate member is received on the upper surface of the tank, and the excess liquid is passed into the tank through the tank opening. Suggest to retrieve.

[0012] Further, a projection is provided at a central portion of the bottom surface of the tank in the axial direction of the fixing roller and at one end in a direction perpendicular to the roller axis, and the supply member is a cloth member. It is proposed to dispose the lower end of the in the tank projection.

Further, it is proposed that the remaining amount of the offset preventing liquid is detected at the tank protrusion. Further, the coating unit is provided so as to be movable between a pressure contact position where the supply member is pressed against the fixing roller or the intermediate member and a separation position where the supply member is separated from the fixing roller or the intermediate member, and during the fixing operation. It is proposed that only the pressed position be moved.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view schematically showing an embodiment of the present invention. The fixing device shown in FIG. 1 includes a main unit 1 and a coating unit 10 of the fixing device. The main unit 1 includes a fixing roller 2, a pressure roller 3, a coating roller 4, a metering blade 5, a separation claw 6,
And so on. In this figure, the housing of the main unit 1 is not shown.

On the other hand, the coating unit 10 located below the main unit 1 includes a tank 11, an oil 12 as an anti-offset liquid stored in the tank, and a felt as a supply member whose lower end is immersed in oil. 13 and one side of the felt 13 while holding and molding.
And a leaf spring 14 for urging one side upward.

The upper surface of the tank 11 is surrounded by side walls 11a.
, And the ceiling portion 11b is configured in a concave shape (a saucer shape) in which it is lowered downward. An opening 15 is provided substantially at the center of the ceiling 11b. One end of the leaf spring 14 as a pressing member is fixed to the lower surface of the tank ceiling 11b, and a part of the felt 13 is attached to the lower surface of the leaf spring 14. The lower end of the felt 13 is impregnated in the oil 12, and the other end is folded back on the upper surface of the leaf spring 14. One side of the bottom surface of the tank 11 protrudes downward to form a convex portion 11c. The convex part 11c
An oil remaining amount detection sensor 16 is provided near the outside of the apparatus.

Now, as shown in FIG. 1A, the main unit 1 of the fixing device and the coating unit 10 in the image forming apparatus.
When the fixing roller 2 is integrally mounted, the application roller (intermediate member) 4 provided in contact with the lower portion of the fixing roller 2
Abuts the felt 13 through the opening 15 of the tank 11;
Leaf spring 14 and felt 1 against the urging force of leaf spring 14
Push the free end of 3 down. As a result, felt 13
A gap d is formed between the front end of the tank 11 and the front end of the ceiling 11b of the tank 11.

The oil in the tank 11 is sucked up by the felt 13, supplied to the application roller 4, and further applied to the fixing roller 2. The oil applied to the fixing roller 2 is regulated to a fixed amount by the metering blade 5, and surplus oil falls onto the ceiling 11 b of the tank 11. The surplus oil is collected in the tank 11 through the gap d. The size of the gap d may be a size necessary for collecting the excess oil, and may be a small gap. Since the size of the gap d is small as described above, even if the liquid surface (oil surface) shakes or tilts when the main unit is moved or the like, the risk of oil leakage can be significantly reduced as compared with the conventional case. it can.

As shown in FIG. 1B, when the application unit 10 is in a single state, the contact of the application roller 4 is released, so that the distal end of the leaf spring 14 rotates counterclockwise in the figure. Then, the right end (returned portion) of the felt 13 in the figure is pressed against the opening end of the tank ceiling 11b, and the opening 15 is closed. Thereby, the coating unit 1
In the case of the single movement, oil leakage in the tank 11 is prevented. Therefore, for example, when exchanging the coating unit, it is possible to avoid a danger that oil in the tank leaks when a new coating unit is attached to the main unit.

In this figure, the transfer paper P carrying the unfixed toner is conveyed from right to left in the figure and passes between the fixing roller 2 and the pressure roller 3. At this time, since the offset prevention oil is applied to the fixing roller 2, the offset of the toner T to the fixing roller 2 is prevented.

Incidentally, the tank 11 has a shape as shown in FIG. That is, the fixing roller 2 has a rectangular planar shape that is long in the axial direction, and the convex portion 11c is formed on one side of the tank bottom surface as described above. The convex portion 11c does not have the size of the entire length in the tank longitudinal direction, and is provided at a predetermined size at the center portion in the tank longitudinal direction (axial direction of the fixing roller). Further, the tank bottom surface is inclined toward the convex portion 11c, and when the remaining amount of oil becomes extremely small, the oil is stored only in the convex portion 11c. The felt 13 has a shape as shown in FIG.
a is disposed in the convex portion 11c of the tank. Note that the oil remaining amount detection sensor 16 (see FIG. 1) is provided at a position corresponding to the convex portion 11c.

With such a configuration of the application unit, when the main unit is installed in an inclined state with the remaining oil amount being extremely small, as shown in FIG.
2 is stored in the protrusion 11c, and the felt 13 can surely suck up the oil. In addition, even when the oil level is very low, the oil level detection sensor 16
Can reliably detect the oil 12, and the tank 11
This prevents erroneous detection of running out of oil even though the oil remains inside.

In a conventional oil tank having a flat bottom surface, when the main unit is installed in an inclined state with the remaining amount of oil being extremely small, as shown in FIG.
2 is offset to the corner of the tank 31, so that not only the felt 13 cannot suck up the oil, but also the remaining amount detection sensor 16 detects that the oil has run out despite the remaining oil. If the application unit is replaced or discarded due to this erroneous detection, the residual liquid (oil) may leak from the discarded application unit and cause environmental pollution. However, in this embodiment, when the remaining oil detection sensor detects that the oil has run out, almost all of the oil in the tank is consumed, and there is little risk of contamination by residual oil.

Next, another embodiment of the present invention will be described. In the fixing device shown in FIG.
Are a tank 12, an oil 12 serving as an anti-offset liquid stored in the tank, an application roller 23 serving as a supply member having a lower part immersed in oil, and a pressing member for urging the application roller 23 upward. And a spring 22. The application unit 20 can be moved in the vertical direction by being guided by a guide member (not shown).
An eccentric cam 24 is provided below the tank 21 to move the coating unit 20.

The upper surface of the tank 21 is surrounded by side walls 21a.
, And the ceiling 21b is configured in a concave shape (a saucer shape) in which it is lowered downward. An opening 25 is provided substantially at the center of the ceiling 21b, and the ceiling 21b is inclined toward the opening 25. The size of the opening 25 is the size of the coating roller 2.
It is smaller than 3.

Now, when the fixing device operates, FIG.
As shown in (2), the eccentric cam is rotated to a predetermined position, and pushes up the tank 21 to move the coating unit 20 upward. When the application unit 20 is raised to some extent, the application roller 23 provided in the tank comes into contact with the fixing roller 2 and the spring 22 is compressed. When the tank 21 moves upward, the movement of the application roller 23 is regulated, so that a gap d is formed between the application roller 23 and the tip of the tank ceiling 21b.

The oil 12 in the tank 21 is applied to the fixing roller 2 by the application roller 23. The oil applied to the fixing roller 2 is regulated to a fixed amount by the metering blade 5, and excess oil falls onto the tank ceiling 21b. The surplus oil is collected in the tank 21 through the gap d. The size of the gap d may be a size necessary for collecting the excess oil, and may be a small gap. Since the size of the gap d is small as described above, even if the liquid surface (oil surface) shakes or tilts when the main unit is moved or the like, the risk of oil leakage can be significantly reduced as compared with the conventional case. it can. In the present embodiment, the tank ceiling 21b is inclined toward the opening 25, so that the surplus oil can be collected smoothly.

When the fixing device does not operate, the eccentric cam 24 is rotated to a different predetermined position to move the coating unit 20 downward as shown in FIG. 2B. When the application unit 20 is lowered to some extent, the application roller 23 provided in the tank is separated from the fixing roller 2, and the application roller 23 closes the opening 25 by the pressing force of the spring 22. This reliably prevents oil leakage when the fixing device is not operating. Therefore, when the apparatus moves with a large danger of oil leakage, it corresponds to the time when the fixing device is not operated, so that oil leakage during the apparatus movement is more reliably prevented.

The fixing device of the embodiment described with reference to FIGS. 1 to 3 may be configured so that the coating unit is moved up and down when the device is operating or not operating. Further, the present invention can be applied not only to a system having a fixing roller with a built-in heater but also to a fixing device having a fixing roller of an induction heating system.

[0030]

As described above, according to the fixing device of the present invention, even if the liquid level (oil level) fluctuates or tilts when the image forming apparatus is moved or the like, the risk of oil leakage is conventionally reduced. The size can be significantly reduced. In addition, the danger of oil leakage when the coating unit alone is avoided.

According to the second aspect of the present invention, since the upper surface of the tank is concave, surplus oil (offset prevention liquid) dropped on the upper surface of the tank can be collected in the tank without spilling.

According to the third aspect of the present invention, the cloth-like supply member can reliably suck up the oil even when the remaining amount of the oil is extremely small. According to the configuration of the fourth aspect, the oil remaining amount detection sensor can reliably detect the oil even when the oil remaining amount is extremely small. Detection is prevented.

According to the configuration of claim 5, oil leakage when the fixing device is not operated is reliably prevented. Therefore, when the apparatus moves with a large danger of oil leakage, it corresponds to the time when the fixing device is not operated, so that oil leakage during the apparatus movement is more reliably prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an embodiment of the present invention.

FIG. 2 is a perspective view showing an oil tank and a coating felt of a coating unit of the fixing device.

FIG. 3 is a cross-sectional view showing a state of an oil tank when the device is installed at an angle.

FIG. 4 is a cross-sectional view illustrating a problem in a conventional oil tank.

FIG. 5 is a cross-sectional view schematically showing another embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 fixing device main unit 2 fixing roller 4 coating roller 5 metering blade 10, 20 coating unit 11, 21 oil tank 12 offset prevention liquid (oil) 13 oil coating felt 14 leaf spring 15, 25 opening 16 oil remaining amount detection Sensor 22 Spring 23 Application roller 24 Eccentric cam

Claims (5)

[Claims] 1. A fixing device comprising: a fixing roller; a pressure roller; and an application unit provided so as to be integrally mounted to an apparatus main body and applying an offset preventing liquid to the fixing roller. A tank for storing the anti-offset liquid, a supply member that is partially immersed in the anti-offset liquid in the tank and supplies the anti-offset liquid to the fixing roller via the fixing roller or the intermediate member, and a supply member. A pressurizing unit that presses the fixing roller or the intermediate member; and when the application unit is not integrally mounted on the apparatus main body, the supply member of the tank is pressed by the pressing force of the pressurizing unit. Closing the opening, and when the application unit is integrally mounted to the apparatus main body, the supply member is pressed by the fixing roller or the intermediate member. The fixing device is further moved so as to open the opening of the tank. 2. The tank according to claim 1, wherein the coating unit is disposed below the fixing roller or the intermediate member, and an upper surface of the tank is formed in a concave shape in which a ceiling portion is dropped downward and a periphery is surrounded by a side wall. An opening of the tank is provided on the ceiling of the upper surface, the amount of application is regulated by the regulating member, the excess liquid falling from the fixing roller or the intermediate member is received on the upper surface of the tank, and the excess liquid is passed into the tank through the tank opening. The fixing device according to claim 1, wherein the fixing device is collected. 3. A protruding portion is provided at a central portion of the bottom surface of the tank in the axial direction of the fixing roller and at one end in a direction perpendicular to the roller axis, wherein the supply member is a cloth member, and the cloth supply member is The fixing device according to claim 1, wherein a lower end portion of the fixing device is disposed inside the tank protrusion. 4. The method according to claim 3, wherein a remaining amount of the offset prevention liquid is detected at the tank protrusion.
3. The fixing device according to claim 1. 5. The coating unit is provided so as to be movable between a pressing position where the supply member is pressed against the fixing roller or the intermediate member and a separation position where the supply member is separated from the fixing roller or the intermediate member. The fixing device according to claim 1, wherein the fixing device is moved to the pressing position only during a fixing operation.