JPH1195599A - Fixing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide the fixing device of a copying machine provided with a releasing agent supply nozzle applying a releasing agent to the thermal fixing roller of the copying machine by a uniform and absolute minimum limit quantity. SOLUTION: The releasing agent supply nozzle 43 applying the releasing agent by the uniform and absolute minimum limit quantity is used to apply the releasing agent to the thermal fixing roller 20 at the fixing device 100 fixing an unfixed image formed on a recording material. The releasing agent supply nozzle 43 is provided with a liquid drop growing means having a projecting or recessed shape to accelerate the formation of the liquid drop of the releasing agent at the positions or peripheral parts of plural releasing agent supply holes 68.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device provided in an image forming apparatus such as an electrophotographic printer or a copying machine, and more particularly to a fixing device for fixing an image to a rotating body for heat and pressure fixing. The present invention relates to a fixing device provided with a mechanism for applying a release agent.

[0002]

2. Description of the Related Art Printers using an electrophotographic process,
2. Description of the Related Art An image forming apparatus such as a copying machine includes a fixing device for fixing an unfixed toner image held on a sheet as a recording medium. There are various fixing systems,
Generally, a pressure heating fixing method is widely used.

[0003] A fixing device based on this pressure heating fixing system,
The fixing roller and the pressure roller are arranged to face each other, and a tubular heating heater such as a halogen lamp is arranged, for example, on the center axis of the fixing roller. The heat generated from the halogen lamp is uniformly radiated to the inner wall of the fixing roller, and the temperature distribution on the outer wall of the fixing roller becomes uniform in the circumferential direction. The outer wall of the fixing roller is heated until its temperature reaches a temperature suitable for fixing (for example, 150 to 200 ° C.). In this state, the fixing roller and the pressure roller rotate in opposite directions while being pressed against each other, and sandwich the sheet holding the toner.
At the nip where the fixing roller and the pressure roller are in pressure contact, the unfixed toner on the sheet is melted by the heat conducted from the fixing roller, and the pressure acting on both rollers is further applied to be fixed on the sheet.

The fixing device using the pressure heating fixing method has a configuration in which the surface holding the toner among the two surfaces of the sheet is in direct contact with the surface of the fixing roller, so that a part of the unfixed toner image on the sheet is fixed to the fixing roller. Easy to transfer to the side.
For this reason, a so-called offset phenomenon occurs in which the toner fused to the fixing roller is transferred again to the rear end of the sheet to stain the sheet, or is transferred again to the next conveyed sheet to stain the sheet. There is a disadvantage that it is easy. Therefore, a fixing device using a pressure heating fixing method has a mechanism for applying a release agent for preventing offset to a fixing roller. As the release agent, silicone oil (hereinafter, also simply referred to as “oil”) is used.

The conventional oil application mechanism includes an oil tank that stores oil and extends along the axial direction of the fixing roller, and a felt or roller that is disposed so as to be immersed in the oil in the oil tank. There is a type in which oil is supplied to an oil application roller in contact with a fixing roller in a planar manner through the felt or the like (Japanese Patent Publication No. 61-1986).
No. 10069). However, since such an oil application mechanism stores a large amount of oil in an opened oil tank, oil spills easily occur, and oil stains easily occur. Further, if the image forming apparatus itself is vibrated or installed at an angle, the oil application mechanism also vibrates or tilts when the fixing device is pulled out, so that oil spills are likely to occur from this point as well. Furthermore, in the oil application mechanism that supplies oil to the oil application roller in a planar manner, it is difficult to make the amount of oil applied to the fixing roller uniform along the axial direction of the fixing roller, and image noise such as oil streaks occurs. There was a problem that it was easy.

In recent years, there has been proposed an oil application mechanism in which a plurality of oil discharge holes are provided in a supply nozzle so that oil is supplied to an oil application roller in the form of dots of liquid droplets (Japanese Patent Laid-Open No. Hei 6 (1994)). JP-A-274061, JP-A-Hei 7-
No. 210025). In a mode in which oil is supplied using a nozzle, a closed-type oil tank can be used, so that oil spillage from the tank can be prevented. Also, by adjusting the operation time of the oil pump, the oil supply can be set arbitrarily from a small amount to a large amount.
There is also an advantage that the range of oil supply can be widened.

However, on the other hand, as shown in FIG. 7A, it is difficult to accurately grow the size of the generated droplet 4 to an intended size. This is because the oil 3 adheres and spreads around the discharge hole 2 and eventually starts growing the droplet 4 together with the oil 3 discharged from the other discharge hole 2 in the vicinity. For this reason, there is a problem that even if the amount of the oil 3 as a whole can be controlled, it is difficult to accurately control the size and the growth rate of the droplet 4 generated by each discharge hole 2.

When the supply nozzle 1 is inclined, as shown in FIG.
Travels along the surface of the supply nozzle 1 and goes down the slope, and is together with the oil 3 discharged from the other discharge holes 2. The oil 3 is dropped at a position shifted from a predetermined dropping position, and the amount of the droplet 4 at that time also becomes larger than the predetermined amount.

[0009]

As described above, in the above-described configuration in which droplets are grown from the discharge holes of the supply nozzle, when the fixing device is tilted, oil from the discharge holes is transmitted along the nozzle surface, so And the droplets do not grow at predetermined positions. This causes problems such as oil dripping in unintended locations, the growth of droplets of the intended size not being obtained, and variations in the ejection amount increasing, resulting in image noise such as oil streaks and offsets. There is.

Therefore, the present invention promotes the formation of stable droplets by forming a structure such as a protrusion or a groove at a position where the release agent drops from the discharge hole provided in the supply nozzle. Thus, the release agent is dropped at a predetermined position without being affected by the inclination of the nozzle, and the release agent can be uniformly supplied in the entire axial direction of the release agent supply nozzle.

[0011] Further, the contact area of the droplet with the release agent supply nozzle is reduced so that the droplet can be freely dropped with a smaller droplet, thereby enabling finer supply control of the release agent. Accordingly, an object of the present invention is to provide a fixing device capable of preventing occurrence of image noise.

[0012]

According to the first aspect of the present invention, there is provided a rotating body for fixing a toner image held on a sheet by heat and pressure, and an axial direction of the rotating body. A coating means extending along the axis and applying a release agent to the rotating body; a supply nozzle extending along the longitudinal direction of the application means and supplying the release agent to the application means from a plurality of discharge holes. The supply nozzle is provided with a droplet growing means for growing the release agent discharged from each of the discharge holes into a droplet and dropping the release agent at a position below the discharge hole. Device.

The droplet growth means is characterized in that the release agent discharged from each of the discharge holes is grown in the form of a droplet and dropped below each of the discharge holes.

According to a second aspect of the present invention, the droplet growth means is formed by a convex body provided near the discharge hole and protruding outward from an outer surface of the supply nozzle. The fixing device according to claim 1, wherein:

[0015] The droplet growing means is characterized by providing the convex body in the vicinity of the discharge hole.

According to a third aspect of the present invention, there is provided the fixing device according to the second aspect, wherein the discharge hole is opened at the top of the convex body.

[0017] The droplet growth means is characterized in that the ejection hole is opened at the top of the convex body.

The invention according to a fourth aspect is characterized in that the droplet growing means is provided in the vicinity of the discharge hole and has a concave structure depressed inward from an outer surface of the supply nozzle. The fixing device according to claim 1, wherein:

[0019] The droplet growth means is characterized in that it is provided with a concave structure which is depressed inward from the outer surface of the supply nozzle in the vicinity of the discharge hole.

According to a fifth aspect of the present invention, there is provided the fixing device according to the fourth aspect, wherein the discharge hole is opened at the bottom of the concave structure.

[0021] The droplet growing means is characterized in that the discharge hole is formed by opening at the bottom of the concave structure.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing a fixing device according to the first embodiment.

The illustrated fixing device 100 is of a pressure heat fixing type, and is incorporated in an image forming apparatus such as a printer having a known electrophotographic image forming means. The fixing device 100 includes a fixing roller 20 provided rotatably in the direction of arrow a, a pressure roller 30 provided in pressure contact with the fixing roller 20, and driven to rotate with the rotation of the fixing roller 20. Heaters 21 and 31 for heating the rollers 20 and 30 and an oil applying mechanism 40 for applying a release agent for preventing offset to at least one of the rollers (the fixing roller 20 in the illustrated example) are provided. The fixing roller 20 and the pressure roller 30 correspond to a rotating body for fixing the toner 11 held on the sheet 10 by heat and pressure. As the release agent, silicone oil is used.

The fixing roller 20 is a hollow metal pipe 2
2 is a roller in which the outer peripheral surface is coated with silicone rubber and a release layer 23 having good release properties and heat resistance to toner is formed. On the central axis of the fixing roller 20, a tubular heating heater such as a halogen lamp 21 is arranged.
The fixing roller 20 has a driving gear (not shown) fixed to one end thereof, and is driven to rotate by a driving source (not shown) such as a motor connected to the driving gear.

The pressure roller 30 is a hollow metal pipe 3
2, a roller provided with a silicone rubber layer 33 on the outer periphery thereof, and the halogen lamp 31 is arranged on the center axis of the roller. The silicone rubber layer 33 is a rubber layer having releasability from which the sheet 10 is easily separated from the surface and having heat resistance. The pressure roller 30 is pressed in a direction toward the fixing roller 20 by a spring material (not shown).
When the toner can be sufficiently fixed only by the halogen lamp 21 built in the fixing roller 20, the pressure roller 3
The 0-side halogen lamp 31 may be omitted.

In the fixing operation, first, a predetermined voltage is applied to the halogen lamps 21 and 31, and the radiant heat generated from the halogen lamps 21 and 31 causes the outer wall temperatures of the fixing roller 20 and the pressure roller 30 to be fixed. Heat to the appropriate temperature. The sheet 10 holding the unfixed toner 11 is conveyed from the right as indicated by an arrow b in FIG. 1 and is sent toward a nip 12 which is a contact portion between the fixing roller 20 and the pressure roller 30. Sheet 1
0 is conveyed while being nipped by the nip portion 12 while the heat from the fixing roller 20, the heat from the pressure roller 30, and the pressure applied from the pressure roller 30 are applied. As a result, the unfixed toner 11 is fixed on the sheet 10. The toner 11 is held on the side of the sheet 10 that contacts the fixing roller 20. The sheet 10 that has passed through the nip portion 12 is naturally separated from the fixing roller 20 by a curvature according to the strength of the sheet 10 itself, and is conveyed leftward in FIG. The sheet 10 is conveyed by a discharge roller (not shown) and discharged onto a discharge tray (not shown).

Next, the configuration of the oil application mechanism 40 will be described.

The oil application mechanism 40 extends along the axial direction of the fixing roller 20 and supplies oil to the fixing roller 2.
The coating unit 41 includes a supply nozzle 43 that extends along the longitudinal direction of the coating unit 41 and supplies oil to the coating unit 41 from a plurality of discharge holes 68. As shown in FIG. 2, the oil application mechanism 40 further includes a closed oil tank 45 for holding oil 44.
And an oil conveying means 46 for feeding the oil 44 stored in the oil tank 45 to the supply nozzle 43.

The application means 41 of the present embodiment includes an oil application roller 50 which is arranged on the sheet carrying side of the fixing roller 20 and presses against the fixing roller 20, and an oil supply roller 53 which presses against the oil application roller 50. , Is provided.

The oil application roller 50 is a roller in which a silicone rubber layer 52 is provided on the outer periphery of a metal pipe 51 as shown in FIG.

As shown in FIG. 2, the oil supply roller 53 is a roller in which an outer periphery of a cylindrical metal core 55 having a plurality of through holes 54 is covered with an oil impregnating material 56. The supply nozzle 43 is disposed on the shaft in a non-rotating state. The through holes 54 are small holes having a predetermined diameter and are formed at substantially equal intervals. This through hole 54
The inner and outer surfaces of the cored bar 55 communicate with each other via. The oil impregnating material 56 is formed of a porous material such as sponge, paper, felt, and silicone rubber. The oil 44 supplied from the supply nozzle 43 to the inner surface of the core bar 55 passes through the through hole 54 of the core bar 55, reaches the outer surface of the core bar 55, and impregnates the oil impregnating material 56.

The oil application roller 50 is rotatably supported by the rotation of the fixing roller 20, while the oil supply roller 53 is supported by the rotation of the oil application roller 50. By such a rotation, the oil 44 supplied from the supply nozzle 43 is transmitted from the oil impregnating material 56 of the oil supply roller 53 to the oil application roller 50, and from the oil application roller 50 to the outer periphery of the release layer 23 of the fixing roller 20. Applied to the surface.

[0034] As shown in FIG.
Is in contact with an oil regulating blade 57 for removing oil not applied to the fixing roller 20. The oil regulating blade 57 has a length substantially equal to the axial length of the oil application roller 50. Oil regulating blade 5
7 is received by an oil pan 58 and is passed through an oil tank 45 via a recovery path (not shown).
Is returned to.

Since the oil tank 45 is a closed type, no oil spills even when a large amount of oil 44 is stored, and no oil spills even when vibration is applied or inclined.

As shown in FIG. 2, the oil transfer means 46 includes an oil pump 60, a tube 61 having one end connected to the oil pump 60 and the other end immersed in the oil 44 in the oil tank 45, and one end connected to the oil 44. Tube 62 connected to oil pump 60 and the other end connected to supply nozzle 43
And is composed of

The supply nozzle 43 has a pipe 65 made of stainless steel or the like, and a supply hole 66 is formed by opening one end of the pipe 65. The other end of the pipe 65 is closed by a plug member 67 and the like. A plurality of discharge holes 68 are formed at a predetermined pitch in the pipe 65, and the release agent discharged into each of the discharge holes 68 grows in the form of a droplet, and a droplet growth in which the release agent is dropped at a position below the discharge hole. A tube 69 as a means is provided.

The tube 69 shown in FIG. 2 is inserted into the discharge hole 68 and fixed, and protrudes outward from the outer surface of the pipe 65. The length of the end portion of the tube 69 inserted into the pipe 65 may be limited by the thickness of the pipe 65 or the thickness of the pipe 65.
5 may protrude into the lumen. Such a tube 69
For example, when the discharge of the oil 44 is stopped, unintended seepage of the oil 44 remaining inside the pipe 65 is prevented when the discharge of the oil 44 is stopped due to the difference in the protrusion length of the oil 44. .

The length of the tube 69 is preferably 5 mm or less, and the inner diameter thereof is set to about 0.5 mm to 1 mm.

FIG. 3A shows how the oil 44 is dripped by the tubes 69. The droplet grows at the tip of each tube 69 and drops at a predetermined position.

FIG. 3B shows a state in which the pipe 65 is tilted. Even if the pipe 65 is tilted, the tubes 69 provided in the respective discharge holes 68 are formed.
Droplet growth preferably occurs at the tip of the. With such a tube 69, the oil 4 discharged from the discharge hole 68
The droplets 4 can be dropped at a predetermined position in a predetermined amount without being pulled down the slope without growing the liquid droplets in the vicinity of the discharge hole 68.

The oil 44 passes through the lumen of the tube 69 and grows at the opening end, and the size of the oil 44 drops reaches a sufficient drop weight to drop. The size and growth rate of the droplet are determined by the area of the open end of the tube 69, and the intended predetermined position and amount of the droplet can be obtained.

FIGS. 4 to 6 show a droplet growing means according to another embodiment of the present invention.

First, FIG. 4A shows a configuration in which a bank-like projection 70, which is one form of a droplet growing means, is provided near the discharge hole 68 instead of the tube 69 in FIG. Oil 4
4 is discharged from the discharge hole 68 and reaches the bank-like projection 70, where the oil 44 is collected at the top and corners of the bank-like projection 70, and the droplet grows. The size and speed of the growing droplets can be controlled by the size of the top of the ridge 70 and the height of the protrusion 70 protruding from the outer periphery of the pipe 65. In addition, by providing a plurality of ridge-shaped projections 70, even if the oil 44 discharged from the discharge holes 68 flows on the left or right side in the axial direction of the pipe 65, intended growth of droplets can be realized.

FIG. 4B shows a bank-like projection 71 having the same shape as the bank-like projection 70 but having an opening of the discharge hole 68 at the top. In the ridge-like projection 71, the oil 44 is discharged from the discharge hole 68 at the top of the ridge, spreads over the top of the ridge, and reaches the end corner of the ridge-like projection 71 to start forming a droplet. . Here, when the droplet 44 grows to a predetermined droplet size, the oil 44 is eventually dropped and the oil 44 is supplied to a predetermined position.

The height of the ridges 70 and 71 protruding from the pipe 65 is preferably about 2 mm, and the width thereof is preferably about 2 mm.

FIG. 5A shows a structure in which a groove 72, which is another form of the droplet growing means, is provided near the discharge hole 68 on the outer surface of the pipe 65. The oil 44 is discharged from the discharge hole 68 and reaches the groove 72, where the groove 72
The oil 44 collects at the bottom and corners of the liquid crystal to grow droplets. The size and speed of the growing droplet can be controlled by the width of the bottom of the groove 72 and the depth of the groove 72 from the outer surface of the pipe 65. Also, by providing a plurality of grooves 72, even if the oil 44 discharged from the discharge hole 68 flows to the left or right side in the axial direction of the pipe 65,
The intended droplet growth can be realized.

FIG. 5B shows the groove 7.
2 is a groove 73 having the same shape as that of No. 2 but having an opening of the discharge hole 68 at its bottom. In the groove 73, the oil 44 is discharged from the discharge hole 68 at the bottom, spreads to the bottom, and reaches the end corner of the groove 73 to start forming a droplet. Here, when the droplet 44 grows to a predetermined droplet size, the oil 44 is dropped and supplied to a predetermined position.

Each of the grooves 72 and 73 preferably has a depression amount from the outer surface of the pipe 65 of about 1 mm and a width of about 2 mm.

FIG. 6A shows a configuration in which a rod-shaped projection 74, which is another form of the droplet growing means, is provided near the discharge hole 68 on the outer surface of the pipe 65. . The oil 44 is discharged from the discharge hole 68 and the rod-shaped projection 74 is formed.
, Where it is transmitted toward the tip of the rod-shaped projection 74 and the droplet grows. The size and speed of the growing droplet can be controlled by the length of the rod-shaped protrusion 74, the amount of protrusion of the rod-shaped protrusion 74 from the outer surface of the pipe 65, and the shape and thickness of the tip of the rod-shaped protrusion 74. By providing a plurality of rod-shaped projections 74, even if the oil 44 discharged from the discharge hole 68 flows around the discharge hole 68 without any intention, the intended growth of the droplet can be realized.

The length of the rod-shaped projection 74 is preferably 3 m.
m, and the thickness thereof is preferably about 1 mm. Further, the shape of the tip portion may be a conical shape, a needle shape, or a flat shape.

FIG. 6B shows a cross section of a structure in which a pin 75 is inserted into the discharge hole 68 instead of the rod-shaped projection 74. In this case, the thickness of the pin 75 is smaller than the diameter of the opening of the discharge hole 68 so that a predetermined gap is formed. This gap allows the oil 44 to flow through the pipe 6
5 and the oil 4
4 reaches the tip portion through the pin 75. Here, the oil 44 grows a droplet, and drops when the droplet reaches the drop weight. By intentionally changing the thickness and the shape of the tip of the pin 75, a drop of a predetermined size can be obtained freely, and the length is preferably about 5 mm.

The end of the inserted pin 75 has a claw 7
7 are provided, and are hooked on the inner wall of the pipe 65 to prevent the pipe 65 from falling off. Further, to prevent the pin 75 from falling into the inside of the pipe 65, the pin 7
A fall prevention collar (not shown) may be provided in the middle of 5.

FIG. 6C is a sectional view of an example of a droplet growing means using a substantially C-ring shaped clip 76. The entire shape of the clip 76 is formed in a C-shape, and an arc portion inside the C-shape fits on the outer periphery of the pipe 65 with a gap. Further, a protrusion is provided near the middle point of the inner circular portion, and the protrusion is inserted into the discharge hole 68. This projection is smaller than the diameter of the opening of the discharge hole 68, so that the oil 44 can be freely discharged from the inside of the pipe 65 when inserted. The oil 44 propagates along the protrusion to grow a droplet at the end of the clip 76. The droplets grown here have a weight suitable for dropping and are simultaneously dropped.

The embodiments described above are described for facilitating the understanding of the present invention, but are not described for limiting the present invention. Therefore, each element disclosed in the above embodiment is intended to include all design changes and equivalents belonging to the technical scope of the present invention.

For example, the ridges 70 and 71 and the groove 7
Although the example in which 2, 73 are provided on the entire circumference of the pipe 65 is shown, the same effect can be obtained by providing only on the circumference of the pipe near the discharge hole 68.

[0057]

As described above, according to the present invention, a stable droplet is formed by forming a structure such as a projection or a groove at a position where a release agent is dropped from a discharge hole provided in a supply nozzle. Promote the formation of As a result, the release agent can be dropped at a predetermined position without being affected by the inclination of the nozzle, and the release agent can be uniformly supplied in the entire axial direction of the release agent supply nozzle. In addition, by reducing the contact area of the droplet with the release agent supply nozzle, it is possible to freely obtain droplets with smaller droplets, and it is possible to control the supply of the release agent more finely. With the above configuration, it is possible to provide a fixing device that can prevent the occurrence of image noise.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a fixing device according to an embodiment of the present invention.

FIG. 2 is a schematic diagram illustrating an oil flow path of a fixing device according to an embodiment of the present invention.

FIG. 3 is a diagram for explaining oil dropping according to the embodiment of the present invention.

FIGS. 4A and 4B are schematic diagrams for explaining an example of a droplet growing means according to an embodiment of the present invention.

FIGS. 5A and 5B are schematic diagrams for explaining an example of a droplet growing means according to an embodiment of the present invention.

FIGS. 6A to 6C are schematic diagrams for explaining an example of a droplet growing means according to an embodiment of the present invention.

FIG. 7 is a diagram for explaining oil dropping of a release agent supply nozzle according to a conventional technique.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... sheet, 11 ... toner, 20 ... fixing roller, 21 ... halogen lamp, 23 ... release layer, 30 ... pressure roller, 31 ... halogen lamp, 40 ... oil application mechanism, 41 ... application means, 43 ... supply nozzle 44, oil, 50, oil application roller, 53, oil supply roller, 54, through hole, 57, oil regulating blade, 65, pipe, 68, discharge hole, 69, tube, 70, ridge projection, 71, ridge 72 ... groove, 73 ... groove, 74 ... rod-like protrusion, 75 ... pin, 76 ... clip, 77 ... claw, 100 ... fixing device.

Claims (5)

[Claims] A rotating member for fixing a toner image held on a sheet by heat and pressure; an applying means extending along an axial direction of the rotating member and applying a release agent to the rotating member; A supply nozzle extending along the longitudinal direction of the application unit and supplying the release agent to the application unit from a plurality of discharge holes, wherein the supply nozzle is discharged from each of the discharge holes. A fixing device provided with a droplet growing means for growing a release agent in the form of droplets and dropping the releasing agent below the discharge holes. 2. The liquid ejecting apparatus according to claim 1, wherein the droplet growing means is provided near the discharge hole and is formed of a convex body protruding outward from an outer surface of the supply nozzle. 3. The fixing device according to claim 1. 3. The fixing device according to claim 2, wherein the discharge hole is opened at the top of the convex body. 4. The apparatus according to claim 1, wherein the droplet growing means is provided in the vicinity of the discharge hole and has a concave structure depressed inward from an outer surface of the supply nozzle. The fixing device as described in the above. 5. The fixing device according to claim 4, wherein the discharge hole is opened at the bottom of the concave structure.