JP3889262B2 - Fixing device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a fixing device that is mounted on an electrophotographic image forming apparatus or the like and includes a roller that fixes a developer (toner) onto the surface of a sheet material (recording paper). In particular, the present invention relates to an improvement in the operation of applying a release agent (oil) to the roller surface.
[0002]
[Prior art]
Conventionally, in a fixing device mounted on an image forming apparatus employing an electrophotographic system such as a copying machine or a printer, a silicone oil or the like is used as a roller for fixing a toner image while nipping and conveying a recording sheet. A release agent is applied. The application of the release agent prevents so-called offset in which a part of the toner on the recording paper adheres to the roller, and prevents the recording paper from being wrapped around the roller, thereby stabilizing high-quality image formation. Can be done.
[0003]
As a configuration for applying oil to the roller, for example, as disclosed in JP-A-8-137317, there is one using a pipe member having a plurality of oil outflow holes. Hereinafter, this configuration will be specifically described.
[0004]
As shown in FIG. 7, the fixing device includes a fixing roller a and a pressure roller b, and an oil tank c is disposed below the rollers a and b. A piezoelectric or electromagnetic pump d is connected to the upper part of the oil tank c, and a pipe member e is connected to the discharge side of the pump d. The pipe member e is positioned above the positions where the rollers a and b are disposed, and extends in parallel with the roller axis. Moreover, oil outflow holes f, f,... Are formed at a plurality of locations along the longitudinal direction of the upper end portion of the pipe member e. By driving the pump d, the oil pumped up from the oil tank c is supplied to the pipe member e, and this oil flows out from the oil outflow holes f, f,. Then, the oil flows down along the outer peripheral surface of the pipe member e and drops from the pipe member e. As shown in FIG. 8 (plan view), an oil receiving plate h having a felt g on the upper surface is disposed at the oil dripping position, and the outer periphery of the oil application roller i is provided on the felt g. The surfaces are touching. Further, the outer peripheral surface of the oil application roller i is also in contact with the outer peripheral surface of the fixing roller a. For this reason, the oil dripped from the pipe member e is applied to the surface of the fixing roller a through the felt g on the oil receiving plate h and the oil application roller i.
[0005]
[Problems to be solved by the invention]
By the way, when the installation state of the image forming apparatus main body is inclined, the arrangement state of the pipe member e is also inclined. Even if the installation state of the main body of the image forming apparatus is horizontal, the arrangement state of the pipe member e may be inclined due to an assembly error of the pipe member e. The oil flowing out from each oil outflow hole f, f,... Flows along the outer peripheral surface of the pipe member e and drops from the lower end thereof. Will flow toward the lower side along the outer peripheral surface of the pipe member e.
[0006]
FIG. 9A shows a dripping state of the oil o when the pipe member e is horizontally disposed. Thus, when the arrangement state of the pipe member e is horizontal, the oil o is uniformly dropped at various places, and the oil o can be uniformly applied over the entire surface of the fixing roller a. . FIG. 9B shows a dripping state of the oil o when the arrangement state of the pipe member e is inclined. Thus, when the arrangement state of the pipe member e is inclined, the oil o flows toward the lower side (to the left in the figure) along the outer peripheral surface of the pipe member e. , The dropping position of the oil o becomes a position different from the predetermined dropping position, resulting in a non-uniform oil application state with respect to the fixing roller a, particularly in a portion where the oil application amount on the fixing roller a is insufficient. There has been a problem that the offset occurs and the recording paper is wound. Further, since oil supply to a part becomes excessive, there is a possibility that oil leakage from the fixing device may occur.
[0007]
The present invention has been made in view of the above points, and an object of the present invention is to provide oil (release agent) to the fixing roller or the pressure roller even when the pipe member is inclined. It is to provide a fixing device capable of uniformly applying the coating.
[0008]
[Means for Solving the Problems]
-Summary of invention-
In order to achieve the above-mentioned object, the present invention is formed in a shape that allows the release agent to uniformly flow down to the release agent supply means that supplies a liquid release agent for application to the roller surface. Provide guide pieces. Accordingly, the release agent can be uniformly applied to the necessary portions of the roller surface regardless of the inclination of the cylindrical body (pipe member) that supplies the release agent.
[0009]
-Solution-
Specifically, a pair of rollers for fixing the developer onto the surface of the sheet material while nipping and conveying the sheet material, and a release agent supply means for supplying a liquid release agent toward at least one surface of these rollers And a fixing device provided with And a mold release agent supply means is provided with a cylindrical body and a guide means. The cylindrical body extends substantially parallel to the roller to which the release agent is supplied and has a hole for releasing the release agent. The guide means causes the release agent that has flowed out of the hole of the cylindrical body to flow down. Further, the guide means is formed in a shape corresponding to the hole for releasing the release agent and having a shape that uniformly spreads in the axial direction of the roller perpendicular to the flow down direction as the release agent flows down in the flow down direction. A guide piece is provided. The specific shape of the guide piece is such that the dimension in the roller axial direction perpendicular to the flow-down direction of the release agent gradually increases in the flow-down direction.
[0010]
Due to this specific matter, when the release agent is applied to the roller surface, the liquid release agent flows out from the hole of the cylindrical body, and this release agent flows down the surface of the cylindrical body. The released release agent flows from the cylindrical body along the guide piece. At this time, the guide piece is formed in a shape that uniformly spreads in the axial direction of the roller perpendicular to the flow-down direction as the mold-release agent flows down in the flow-down direction. It is possible to prevent the wasteful supply of oil. That is, even if the cylindrical body is inclined, it is possible to evenly apply the release agent to the roller surface by each guide piece.
[0011]
When the upper end of the guide piece is positioned in the immediate vicinity of the release agent outflow hole, the release agent that has flowed out of the release agent outflow hole is not reduced even if the width of the upper end portion of the guide piece is reduced. It is guided smoothly by the guide piece, and wasteful release agent can be reduced while avoiding an increase in size of the guide piece. For example, when the guide piece is formed of a material having permeability, the release agent is smoothly guided even if the guide piece is new.
[0012]
Also, when the upper end of the guide piece is brought into contact with the release agent outflow hole in the surface of the cylindrical body, the release agent flowing out from the release agent outflow hole is smoothly guided by the guide piece. It is possible to reduce wasteful release agents.
[0013]
Further, when one end of the guide piece comes into contact with the surface of the cylindrical body and the other end passes through the vertical lower side of the cylindrical body and extends toward the roller to which the release agent is supplied, the mold release Even if the release agent that has flowed out of the agent outlet hole falls from the cylindrical body without being guided by the guide piece, the release agent is received by the guide piece and guided toward the roller. Become. For this reason, the release agent leakage (oil leakage) from the apparatus can be prevented.
[0014]
When the guide piece is formed of a material having permeability, it is possible to avoid a situation in which the release agent that has flowed into the guide piece drops from a location other than the lower end of the guide piece. It is possible to reliably supply the roller.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
[0016]
FIG. 1 is a perspective view showing a part of a fixing device according to this embodiment. FIG. 2 is a side view showing a part of the fixing device in section. As shown in these drawings, the fixing device includes a fixing roller 1 and a pressure roller 2 that are arranged in parallel in the vertical direction and are in pressure contact with each other. Each of the fixing roller 1 and the pressure roller 2 has a rubber layer made of silicon rubber on an aluminum pipe, and includes heaters 11 and 21 made of halogen lamps therein. A driving source (for example, a motor) (not shown) is connected to the fixing roller 1, and each roller 1, 2 rotates in the direction indicated by an arrow in the figure as the driving source is driven. The toner image on the recording paper P is heated and fixed while the recording paper P is nipped and conveyed.
[0017]
Around the fixing roller 1, an upper peeling claw 12, an upper cleaning roller 13, a fixing roller temperature detector 14, and an oil application roller 3 are disposed. On the other hand, a lower peeling claw 22, a lower cleaning roller 23, and a pressure roller temperature detector 24 are disposed around the pressure roller 2.
[0018]
Each of the peeling claws 12 and 22 is for peeling the recording paper P to be wound around the rollers 1 and 2 from the surface of the rollers 1 and 2. Each of the cleaning rollers 13 and 23 is a felt roller, and collects offset toner attached to the surfaces of the rollers 1 and 2 by sliding contact with the surfaces of the fixing roller 1 and the pressure roller 2. is there.
[0019]
Each of the roller temperature detectors 14 and 24 is a thermistor and detects the surface temperature of the rollers 1 and 2 that are in contact with each other. The temperature detection results of the roller temperature detectors 14 and 24 are sent to a fixing controller (not shown). The fixing control unit controls the operation of the power supply unit based on the detection results of the roller temperature detectors 14 and 24 to turn on / off the heaters 11 and 21 which are heat sources in the rollers 1 and 2. The temperatures of the rollers 1 and 2 are adjusted.
[0020]
The oil application roller 3 is a roller whose surface is made of rubber, and receives oil (liquid release agent) from an oil supply mechanism 4 as a release agent supply means described later, and applies this oil to the surface of the fixing roller 1. To do.
[0021]
Next, the oil supply mechanism 4 for supplying oil to the surface of the fixing roller 1 will be described.
[0022]
An oil tank 41 is installed at the lower end of the fixing device. Oil O is accommodated in the oil tank 41. As this oil O, dimethyl silicone oil having a viscosity of 100 CS to 300 CS can be used, but modified silicone oil (for example, reactive silicone oil, non-reactive silicone oil, etc.) may be used. However, it is not preferable that the viscosity is high because pump suction becomes difficult.
[0023]
A pump 42 is connected to the upper part of the oil tank 41, and a pipe member 44 is connected to the discharge side (upper side in the drawing) of the pump 42 via a tube 43. The pipe member 44 is installed in parallel with the fixing roller 1 at an obliquely upper side of the fixing roller 1. The pipe member 44 is formed with oil outflow holes 45, 45,... At a plurality of locations in the longitudinal direction. Therefore, the oil O pumped up from the oil tank 41 as the pump 42 is driven is supplied to the pipe member 44 through the tube 43 and flows out from the oil outlet holes 45, 45,. It is like that. Further, one end (the end opposite to the side connected to the pump 42) of the pipe member 44 is closed by caulking processing or the like, and each oil outflow occurs when oil is supplied to the pipe member 44. The oil is prevented from flowing out from places other than the holes 45, 45,. The length dimension of the pipe member 44 is substantially the same as that of the fixing roller 1 and the pressure roller 2, and the region where the oil outflow hole 45 is formed is the dimension in the longitudinal direction of these rollers 1 and 2. It corresponds to.
[0024]
The inner diameter of the pipe member 44 is determined by the discharge capacity of the pump 42. For example, when the oil outflow rate per unit time of the pump 42 is about 3 to 30 g / min, the inner diameter of the pipe member 44 is 5-10 mm is suitable. The material of the pipe member 44 is not particularly limited, and a metal pipe made of aluminum, iron, or brass can be used. Furthermore, the oil outflow hole 45 preferably has a diameter of about 0.5 to 1.5 mm, and the oil outflow hole 45 can be formed by, for example, press working or laser processing. Further, the number of the oil outflow holes 45 is arbitrary, but it is necessary that the number of the oil outflow holes 45 be such that the oil O can be uniformly applied to substantially the entire outer peripheral surface of the fixing roller 1 (for example, 7 to 9). In this embodiment, the oil outflow holes 45, 45,... Are all set to have the same diameter. However, since oil O is supplied from one end of the pipe member 44, the pressure loss is taken into consideration. The diameter of the oil outflow holes 45, 45,... Is gradually increased from the upstream side to the downstream side of the pipe member 44 so that the oil discharge amount from each oil outflow hole 45, 45,. Also good. In addition, each numerical value mentioned above is not limited to this.
[0025]
Below the pipe member 44, an oil receiving plate 46 that is inclined is provided. Between the pipe member 44 and the oil receiving plate 46, a felt guide sheet 5 which is a characteristic feature of this embodiment is disposed. That is, the oil receiving plate 46 receives the oil O flowing out from the oil outflow holes 45, 45,... Of the pipe member 44 along the guide sheet 5. The configuration of the guide sheet 5 and the oil O flowing operation will be described later.
[0026]
Further, the outer peripheral surface of the oil application roller 3 is in contact with the lower end of the guide sheet 5, and the oil O soaked into the guide sheet 5 is applied to the outer peripheral surface of the fixing roller 1 through the oil application roller 3. It has become.
[0027]
Further, a rubber coating blade 48 is in contact with the outer peripheral surface of the oil application roller 3, and the oil O on the outer peripheral surface of the oil application roller 3 is made uniform by the application blade 48 in a thin film shape. ing.
[0028]
Further, an oil pan 49 is disposed below the oil receiving plate 46. The oil pan 49 is for collecting the oil O when excess oil that has not adhered to the oil application roller 3 drops from the oil receiving plate 46. The oil pan 49 is connected to the oil tank 41 by an oil recovery tube 49 a so that the recovered surplus oil is returned into the oil tank 41. That is, the oil O is circulated between the oil tank 41 and the pipe member 44, and only a necessary amount of oil can be applied to the outer peripheral surface of the fixing roller 1 through the oil application roller 3. Yes.
[0029]
An oil remaining amount detection sensor 41 a for detecting the remaining amount of oil in the oil tank 41 is disposed inside the oil tank 41. When the remaining oil amount detection sensor 41a detects that the remaining amount of oil in the oil tank 41 has become a predetermined amount or less, a warning is displayed on the display panel of the image forming apparatus, and the user is informed of oil. The supply is encouraged. Further, when the oil is insufficient, the image forming apparatus may be temporarily disabled.
[0030]
Next, the characteristic part of this form in the pipe member 44 and its peripheral part will be described. As shown in FIGS. 3 and 4, the guide sheet 5 as a guide means is attached to the side surface of the pipe member 44. The guide sheet 5 is made of a felt having a thickness of about 1 mm, for example, and has a plurality of guide pieces 51, 51,... Formed in a triangular shape so that the width dimension gradually increases toward the lower side. .. Are integrally formed with a connecting portion 52 that connects the lower end edges of the guide pieces 51, 51,... In the horizontal direction. Further, the guide pieces 51, 51,... Are arranged corresponding to the positions of the oil outflow holes 45, 45,. In other words, the guide pieces 51, 51,... Are positioned so that the center line of the triangular guide piece 51 and the position of the oil outflow hole 45 overlap in the vertical direction.
[0031]
In this embodiment, the oil outflow hole 45 of the pipe member 44 is formed at the upper end of the pipe member 44. However, the oil outflow hole 45 of the pipe member 44 is formed more than the upper end of the pipe member 44 as shown in FIG. You may form in the position of the side (right side in FIG. 5) where the guide sheet 5 is stuck. The position of the oil outflow hole 45 is such that an angle α formed by a straight line L1 connecting the axis of the pipe member 44 and the upper end and a straight line L2 connecting the axis of the pipe member 44 and the center of the oil outflow hole 45 is 5 for example. It is set to be -30 ° (preferably 5-10 °). According to this configuration, most of the oil O flowing out from the oil outflow hole 45 flows on the right side surface of the pipe member 44 in FIG. 5 (see the arrow in the figure), and this oil O smoothly flows into the guide seat 5. It is designed to be absorbed.
[0032]
Further, as described above, the guide pieces 51, 51,... Are arranged corresponding to the positions of the oil outflow holes 45, 45,. The oil O that has flowed out of the gas flows into the guide pieces 51 positioned below the oil O. For this reason, the flow rate of the oil O in each guide piece 51, 51, ... can be made into substantially the same amount mutually. Since each guide piece 51, 51,... Is formed in a triangular shape, the oil O soaked into the guide piece 51 flows down the guide piece 51, as shown by the solid line in FIG. It will flow equally toward the lower end of 51 (the base of the triangle). The oil O is applied to the outer peripheral surface of the fixing roller 1 from the lower end of each guide piece 51, 51,... Via the connecting portion 52 and the oil application roller 3.
[0033]
As described above, according to the present embodiment, the oil flowing out from the oil outflow holes 45, 45,... Of the pipe member 44 and flowing down along the guide pieces 51, 51,. Since the oil O is formed in a shape that uniformly spreads in the direction perpendicular to the flow direction as the oil O flows down, the oil O is uniformly applied to the necessary portions of the surface of the fixing roller 1. That is, wasteful oil supply can be prevented by flowing down only in the direction of the arrow shown by the solid line without flowing down in the direction of the arrow shown by the broken line in FIG. 4, and the pipe member 44 is inclined. Even in the situation, the oil O can be evenly applied to the surface of the fixing roller 1 by the guide pieces 51, 51,. By uniformizing the oil application on the surface of the fixing roller 1, the occurrence of the offset can be avoided and the winding of the recording paper P around the rollers 1 and 2 can be prevented, so that high-quality image formation is stabilized. Can be performed.
[0034]
In this embodiment, as shown in FIG. 3, the upper end of the guide piece 51 is in contact with the surface of the pipe member 44, and the lower end passes through the pipe member 44 vertically below and extends toward the oil application roller 3. Therefore, even if the oil O flowing out from the oil outflow hole 45 falls from the pipe member 44 without being guided by the guide piece 51, the oil O is received by the guide piece 51 as shown by the arrows in FIG. It is guided toward the oil application roller 3. For this reason, the release agent leakage (oil leakage) from the apparatus can be prevented.
[0035]
-Other embodiments-
In the above-described embodiment, the case where the upper ends of the guide pieces 51, 51,... Of the guide sheet 5 are brought into contact with the pipe member 44 has been described, but as shown in FIG. The upper ends of the pieces 51, 51,... May be arranged at positions corresponding to the oil outflow holes 45, 45,. In this case, the upper end of each guide piece 51 is preferably as close as possible to the pipe member 44.
[0036]
In the above embodiment, the oil O flowing down the guide pieces 51, 51,... Of the guide sheet 5 is applied to the outer peripheral surface of the fixing roller 1 through the oil application roller 3. The present invention is not limited to this, and the oil flowing down the guide pieces 51, 51,... May be applied directly to the outer peripheral surface of the application roller 3.
[0037]
Further, the configuration in which the oil supply mechanism 4 applies the oil O to the outer peripheral surface of the fixing roller 1 has been described. However, the oil supply mechanism 4 can be applied to a configuration in which the oil O is applied to the outer peripheral surface of the pressure roller 2 or It is also possible to apply to a configuration in which oil O is applied to the outer peripheral surface.
[0038]
Further, the shape of the guide piece 51 of the guide sheet 5 may be any shape as long as the width dimension gradually increases toward the lower side, and is not necessarily limited to a triangle.
[0039]
In addition, a configuration in which the oil outflow hole 45 is covered by the upper end portion of the guide piece 51 of the guide sheet 5 may be employed. According to this, even when the oil supply pressure to the pipe member 44 is higher than necessary, the situation where the oil O from the oil outflow hole 45 is scattered can be avoided, and the oil outflow hole 45 can be avoided. It is possible to supply all of the oil O flowing out of the guide sheet 5.
[0040]
【The invention's effect】
As described above, according to the present invention, the release agent supplying means for supplying the liquid release agent to be applied to the roller surface is configured to flow uniformly in the axial direction of the roller. A formed guide piece is provided. For this reason, it is possible to apply the release agent evenly to the necessary portions of the roller surface regardless of the inclination of the cylindrical body that supplies the release agent. As a result, it is possible to eliminate problems such as occurrence of offset and winding of the recording paper due to non-uniformity of oil application to the rollers, and high-quality image formation can be stably performed. In addition, oil supply to a part is not excessive and oil leakage does not occur.
[0041]
Further, when one end of the guide piece is in contact with the surface of the cylindrical body and the other end extends toward the roller to which the release agent is supplied by passing vertically below the cylindrical body, Even if the release agent that has flowed out of the agent outlet hole falls from the cylindrical body without being guided by the guide piece, the release agent is received by the guide piece and guided toward the roller. . For this reason, leakage of the release agent from the apparatus (oil leakage) can be prevented, and the reliability of the fixing apparatus can be improved.
[0042]
Further, when the guide piece is formed of a material having permeability, it is possible to avoid a situation in which the release agent that has flowed into the guide piece drops from a position other than the lower end of the guide piece. The reliability of uniform oil application can be improved.
[Brief description of the drawings]
FIG. 1 is a perspective view illustrating a part of a fixing device according to an embodiment.
FIG. 2 is a side view showing a part of the fixing device in section.
FIG. 3 is a side view showing an arrangement state of a guide sheet.
FIG. 4 is a front view showing an arrangement state of a guide sheet.
FIG. 5 is a cross-sectional view for explaining a modified example of the oil outflow hole.
6 is a view corresponding to FIG. 4 for explaining a modified example of the guide sheet. FIG.
FIG. 7 is a view corresponding to FIG. 1 in a conventional example.
FIG. 8 is a plan view of a pipe member and its peripheral part in a conventional example.
FIGS. 9A and 9B are diagrams showing a state in which oil is dripped from a pipe member in a conventional example, where FIG. 9A shows a horizontal arrangement of the pipe member, and FIG. It is a figure which shows each case.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fixing roller 2 Pressure roller 4 Oil supply mechanism (release agent supply means)
44 Pipe member (cylindrical body)
45 Oil outflow hole 5 Guide sheet (guide means)
51 Guide piece O Oil (release agent)
P Recording paper (sheet material)

Claims (6)

Fixing provided with a pair of rollers for fixing the developer on the surface of the sheet material while nipping and conveying the sheet material, and a release agent supply means for supplying a liquid release agent toward at least one surface of these rollers In the device
The release agent supplying means is
A cylindrical body extending substantially parallel to the roller to which the release agent is supplied and having a hole for releasing the release agent;
Guide means for flowing down the release agent that has flowed out of the hole of the cylindrical body,
The guide means is arranged corresponding to the hole for releasing the release agent, and is formed in a shape that uniformly spreads in the axial direction of the roller perpendicular to the flow down direction as the release agent flows down in the flow down direction. A fixing device comprising a piece. The fixing device according to claim 1.
The fixing device is characterized in that the guide piece is formed in a shape in which the dimension in the roller axial direction perpendicular to the flow-down direction of the release agent gradually increases in the flow-down direction. The fixing device according to claim 1 or 2,
A fixing device characterized in that the upper end of the guide piece is positioned in the immediate vicinity of the release agent outflow hole. The fixing device according to claim 3.
A fixing device, wherein an upper end of the guide piece is in contact with a release agent outflow hole in the surface of the cylindrical body. In the fixing device according to any one of claims 1 to 4,
One end of the guide piece is in contact with the surface of the cylindrical body, and the other end of the guide piece extends toward a roller through which the release agent is supplied by passing vertically below the cylindrical body. In the fixing device according to any one of claims 1 to 5,
The fixing device, wherein the guide piece is formed of a material having permeability.

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