JP3802359B2 - 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. 6, 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. 7 (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 disposed 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. 8A shows a dripping state of the oil o when the pipe member e is horizontally arranged. 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. 8B 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 object, the present invention is formed in a release agent supply means for supplying a liquid release agent for application onto the roller surface in a shape that regulates the flow direction of the release agent. A guide piece is provided. Accordingly, the release agent can be applied to the necessary portion 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 to the surface of the sheet material while sandwiching and conveying the sheet material, and a release agent supply means for supplying a liquid release agent to at least one surface of these rollers A fixing device provided is assumed. 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 provided with a guide piece that is formed of a permeable material and has a shape in which the width dimension gradually decreases toward the lower side so as to regulate the flow-down direction of the release agent. The upper end portion of the guide piece is brought into contact with the side surface of the cylindrical body, and the hole of the cylindrical body is formed on the side where the guide piece is slightly in contact with the upper end of the cylindrical body.
[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, since the guide piece is formed in a shape in which the width dimension gradually decreases toward the lower side, the flow-down direction of the release agent is directed to the portion with the shortest width dimension at the lower end of the guide piece. Become. For example, when the guide piece is formed in an inverted triangle, the release agent flows down toward the top of the lower end. Therefore, it becomes possible to regulate the flow-down direction of the release agent according to the shape of the guide piece. Even if the cylindrical body is inclined, the oil is directed toward the lower end of the guide piece. The flow-down direction is regulated, and the release agent can be applied to the necessary portion of the roller surface.
Moreover, since 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 becomes possible to accurately regulate the flow direction of the agent.
Further, the upper end portion of the guide piece is brought into contact with the side surface of the cylindrical body so that the release agent flowing out from the hole of the cylindrical body is allowed to flow down, while the hole of the cylindrical body is formed more than the upper end of the cylindrical body. Since it is formed on the side where the guide piece is slightly in contact, most of the release agent that has flowed out of the hole of the cylindrical body can be flowed in the direction toward the guide piece. That is, it is possible to avoid a situation in which the release agent that has flowed out of the hole of the cylindrical body drops without flowing through the guide piece.
[0011]
Moreover, the following are mentioned as a specific structure of a guide piece. In other words, a plurality of guide pieces are arranged along the roller extending direction. According to this, the flow-down direction of the release agent is a direction regulated by each guide piece. In other words, the flow point of the release agent can be set at the lower end of each guide piece, and it is possible to supply the release agent evenly to a plurality of locations, and supply the release agent to almost the entire roller surface. Can be performed reliably.
[0014]
Moreover, the following is mentioned as a structure which specified the positional relationship of the hole of a cylindrical body and a guide piece concretely. That is, holes in the cylindrical body are formed at a plurality of locations along the roller extending direction, and each guide piece is arranged corresponding to the position of the hole in the cylindrical body. Similarly, holes in the cylindrical body are formed at a plurality of locations along the roller extending direction, and a plurality of guide pieces are arranged corresponding to the holes in the cylindrical body. According to these configurations, since the oil flowing out from each hole flows into the guide pieces corresponding to the holes, the oil flow rate in each guide piece can be made uniform. For this reason, it is possible to reliably apply the release agent to substantially the entire roller surface. In particular, according to the latter configuration, the oil pour point from the guide means can be increased without increasing the number of holes in the cylindrical body, and the release agent can be applied to almost the entire roller surface. Can be performed more reliably.
[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). Further, since the oil O is supplied from one end of the pipe member 44, the diameter of the oil outlet holes 45, 45,... Is increased from the upstream side to the downstream side of the pipe member 44 in consideration of pressure loss. The oil discharge amount from each oil outflow hole 45, 45,... In addition, each numerical value mentioned above is not limited to this.
[0025]
Below the pipe member 44, there is provided an oil receiving plate 46 that is inclined and a felt material 47 is mounted on the oil receiving plate 46. In other words, the oil receiving plate 46 receives the oil O flowing out from the oil outflow holes 45, 45,... Of the pipe member 44 and flows down toward the felt material 47, so that the oil O is soaked into the felt material 47. It comes to let you.
[0026]
Further, the outer peripheral surface of the oil application roller 3 is in contact with the felt material 47, and the oil O soaked into the felt material 47 is applied to the outer peripheral surface of the fixing roller 1 through the oil application roller 3. Yes.
[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 FIG. 3, a guide sheet 5 as 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 an inverted triangular shape so that the width dimension gradually decreases toward the lower side. These guide pieces 51, 51,... Are integrally formed with a connecting portion 52 that connects the upper end edges of the guide pieces 51,. Further, the guide pieces 51, 51,... Are arranged corresponding to the positions of the oil outflow holes 45, 45,. That is, the guide pieces 45, 45,... Are formed so that the center line of the inverted triangular guide piece (straight line L indicated by a one-dot chain line in FIG. 3) and the position of the oil outflow hole 45 overlap in the vertical direction. .
[0031]
Further, as shown in FIG. 5 (a cross-sectional view taken along line IV-IV in FIG. 3), the oil outflow hole 45 of the pipe member 44 is on the side where the guide sheet 5 is adhered from the upper end of the pipe member 44. It is formed at a position (right side in FIG. 5 ). 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 °). For this reason, 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 is smoothly absorbed by the guide sheet 5. It is like that.
[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 an inverted triangle shape, the oil O soaked into the guide piece 51 flows down the guide piece 51, and the flow direction is the lower end (inverted triangle) of the guide piece 51. Direction toward the lower apex). The oil O drops from the lower ends of the guide pieces 51, 51,..., Soaks into the felt material 47 through the oil receiving plate 46, and is applied to the outer peripheral surface of the fixing roller 1 through the oil application roller 3. Will be.
[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,. The flow direction is regulated toward the apex of the lower end of each. For this reason, even if the pipe member 44 is inclined, it is possible to apply the oil O to a necessary portion of the surface of the fixing roller 1 by the regulation in the flow direction. The oil O can be uniformly and reliably applied to substantially the entire surface of the fixing roller 1. 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]
-Modification-
Next, a modified example of the present invention will be described. This example is a modification of the shape of the guide sheet 5, and other configurations are the same as those of the above-described embodiment. Therefore, only the shape of the guide sheet 5 will be described here.
[0035]
The guide sheet 5 of the above-described embodiment has a configuration in which one guide piece 51 is disposed corresponding to the position of each oil outflow hole 45, 45,... Of the pipe member 44. That is, the guide pieces 45, 45,... Are formed so that the center line of the inverted triangular guide piece (straight line L indicated by a one-dot chain line in FIG. 3) and the position of the oil outflow hole 45 overlap in the vertical direction. .
[0036]
As shown in FIG. 4 , the guide sheet 5 of the present embodiment has two inverted triangular guide pieces 51 </ b> A and 51 </ b> B arranged corresponding to the positions of the oil outflow holes 45, 45,. It has been configured. That is, two inverted triangular guide pieces 51A and 51B are formed adjacent to each other, and the boundary line between these guide pieces 51A and 51B (the straight line L indicated by a one-dot chain line in FIG. 4 ) and the position of the oil outflow hole 45 are The guide sheet 5 is formed so as to overlap in the vertical direction.
[0037]
According to this configuration, the oil dripping point from the guide sheet 5 can be increased without increasing the number of the oil outflow holes 45, and more uniform application of the oil O to the entire surface of the roller can be achieved. It can be done more reliably.
[0038]
-Other embodiments-
In the above-described embodiment, the oil O dropped from the guide pieces 51 of the guide sheet 5 is once received by the oil receiving plate 46, and this oil O passes through the felt material 47 and the oil application roller 3 to the fixing roller 1. It was made to apply | coat to an outer peripheral surface. The present invention is not limited to this, and the oil dropped from the guide pieces 51, 51,... May be directly dropped onto the outer peripheral surface of the oil application roller.
[0039]
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.
[0040]
Further, the shape of the guide piece 51 of the guide sheet 5 may be any shape as long as the width dimension gradually decreases toward the lower side, and is not necessarily limited to an inverted triangle.
[0041]
【The invention's effect】
As described above, according to the present invention, the guide formed in a shape that regulates the flow direction of the release agent to the release agent supply means for supplying the liquid release agent to be applied to the roller surface. A piece is provided. For this reason, it is possible to apply the release agent to a necessary portion 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.
[0042]
Further, the guide piece, because it forms a material having a permeability, it is possible to avoid a situation where the release agent that has flowed into the guide piece will be dropped from the portion other than the lower end of the guide piece, the release The flow direction of the agent can be accurately regulated, and the reliability of uniform oil application to the roller can be improved.
[0043]
Furthermore, since the hole of the cylindrical body is formed on the side where the guide piece is slightly in contact with the upper end of the cylindrical body, most of the release agent flowing out from the hole of the cylindrical body is used as the guide piece. This can prevent the situation where the release agent that has flowed out from the hole in the cylindrical body drops without flowing through the guide piece, and this also ensures the reliability of uniform oil application to the roller. Can be improved.
[0044]
In addition, when a plurality of guide pieces are arranged corresponding to the holes of the cylindrical body, the flow point of the oil from the guide means can be set without increasing the number of holes of the cylindrical body. Therefore, it is possible to more reliably apply the release agent to almost the entire roller surface.
[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 of a pipe member.
FIG. 4 is a view corresponding to FIG. 3 in a modified example.
5 is a cross-sectional view taken along the line IV-IV in FIG.
6 is a view corresponding to FIG. 1 in a conventional example.
FIG. 7 is a plan view of a pipe member and its peripheral part in a conventional example.
FIGS. 8A and 8B are diagrams showing a state in which oil is dripped from a pipe member in a conventional example, where FIG. 8A shows a horizontal arrangement of the pipe member, and FIG. 8B shows an inclined arrangement of the pipe member. 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 51 Guide piece O Oil (release agent)
P Recording paper (sheet material)

Claims (4)

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,
Said guide means is formed of a material having permeability, has a and releasing agent guide piece has a width dimension toward the lower side is formed to gradually decrease becomes shaped so as to regulate the flow-down direction of the The upper end of the guide piece is in contact with the side surface of the cylindrical body, while the hole of the cylindrical body is formed on the side where the guide piece is slightly in contact with the upper end of the cylindrical body. a fixing device characterized in that is. The fixing device according to claim 1.
A plurality of guide pieces are arranged along a roller extending direction. The fixing device according to claim 2.
The hole of the cylindrical body is formed at a plurality of locations along the roller extension direction,
Each of the guide pieces is arranged corresponding to the position of the hole of the cylindrical body. The fixing device according to claim 2.
The hole of the cylindrical body is formed at a plurality of locations along the roller extension direction,
A plurality of guide pieces are arranged corresponding to the holes of the cylindrical body, respectively.

Images