JP2001147612A - Oil applicator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the adhesion of foreign matter, such as paper dust, to the front end of the regulating blade 7 of an oil applicator 3 of a scooping up system. SOLUTION: This oil applicator 3 of a scooping up system scoops up the oil 20 in a tank 18, holds the oil on the surface of a application roller 4 and regulates the oil by the regulating blade 7. The force of the front end of the regulating blade 7 which comes into pressurized contact with the surface of the coating application roller 4 is varied by varying the tensile force of a spring 8. As a result, the adhesion of the paper dust, etc., to the front end of the regulating blade 7 may be prevented and even if the paper dust, etc., adhere to the front end, the paper dust, etc., sticking thereto are peeled by the pressure fluctuation described above and can be again mixed into the oil of the application roller surface.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an oil applying apparatus for applying oil (release agent) to a peripheral surface of a fixing roller for fixing a toner image on recording paper by thermocompression.

[0002]

2. Description of the Related Art In a fixing device mounted on an electrophotographic image forming apparatus, a release agent (silicone oil) is applied to a peripheral surface of a fixing roller in order to separate a recording sheet after fixing a toner image from the fixing roller. An oil application device for applying is provided.

FIG. 4 shows an example of a pumping type oil application device. The illustrated oil applicator includes a pumping roller 6 that is partially immersed in oil 19 in an oil tank 18 and is rotated in the direction of the arrow, and a supply roller that is pressed against the roller 6 and rotated in the direction of the arrow. A roller 5 which is pressed against the supply roller 5 and is pressed against the upper fixing roller 1 to be coated with oil and is rotated in the direction of the arrow to draw oil 19 in an oil tank 18;
Of the application roller 4 via the peripheral surface of the supply roller 5 and the peripheral surface of the supply roller 5, and the amount of the support is regulated by a regulating blade 7 provided such that the tip portion is close to the peripheral surface of the application roller 4. This is a device for applying the toner to the peripheral surface of the upper fixing roller 1 which is rotated in the direction of the arrow after being regulated to be thin and uniform.

[0004] The pumping type oil application device has excellent ability to uniformly apply oil to the peripheral surface of the fixing roller.
Even when a large number of recording papers are continuously passed, a necessary and sufficient oil can be applied uniformly and without interruption, so that an image forming apparatus particularly required to have high image quality (eg, a color copying machine) Tend to be mounted on In addition, since the pumping type oil application device is relatively expensive and large, it is not used for an inexpensive image forming device or a small-sized image forming device.

[0005]

The above-described excellent capability of the pumping type oil application device is such that a sufficient amount of oil is supplied from the supply roller 5 to the application roller 4 and the oil is reduced to a required amount by the regulating blade 7. It is realized by applying the toner to the fixing roller 1 after the regulation. For this reason,
In a pumping type oil application device, a regulating means such as a regulating blade 7 is indispensable. However, foreign matter such as paper powder and toner gradually adheres to the tip (contact portion) of the regulating blade 7, There was a problem that an image defect called an oil streak occurred in an image on the recording paper due to the foreign matter. For this reason, a technique for preventing foreign matter such as paper powder from adhering to the regulating means is desired.

An object of the present invention is to prevent foreign matter such as paper dust from adhering to a regulating means of a pumping type oil application device.

[0007]

According to the first aspect of the present invention, there is provided a pump roller partially immersed in oil in a tank, a supply roller pressed against the pump roller, and a supply roller pressed against the supply roller. An application roller that is pressed against a fixing roller to be applied with oil, and the oil in the tank is carried on the surface of the application roller via the surface of the pumping roller and the surface of the supply roller, and the amount of the carried oil is regulated. An oil applying device that applies the oil to the surface of the fixing roller after the contact is regulated by the means, wherein the regulating unit contacts a surface of the applying roller to regulate an oil carrying amount on the surface to a predetermined amount. An oil applicator comprising: a regulating member provided; and pressure varying means for varying a pressure at which a contact portion of the regulating member contacts a surface of the application roller. Since the pressure at which the contact part of the regulating means contacts the surface of the application roller is varied by the pressure varying means, foreign matter such as paper dust hardly adheres to the contact part. Further, even when foreign matter such as paper dust adheres, the adhered foreign matter such as paper powder is peeled off from the contact portion due to the pressure fluctuation, and again enters the oil on the surface of the application roller. Is prevented from becoming excessively large. The center pressure of the pressure fluctuation may be any side higher than the normal contact pressure, lower than the normal contact pressure, near the normal contact pressure,
In consideration of the range (amplitude) of the pressure fluctuation, it is determined so that the above-described operation is favorably performed. Note that the above configuration also includes a configuration in which the pumping roller and the supply roller are shared (= a single roller has the functions of the pumping roller and the supply roller). Oil is a material having a function as a release agent. For example, silicone oil is used, but another release agent may be used.

According to a second aspect of the present invention, in the first aspect, the pressure varying means applies a pressure to the surface of the application roller of the contact portion during a period in which the fixing operation is not performed and the application roller is rotating. An oil application device characterized by varying a contact pressure. If the pressure variable means is operated during the execution of the fixing operation, the thickness of the oil layer on the surface of the application roller tends to be uneven, which may appear as a defect in the recorded image. For this reason, the pressure variable means is not operated during the fixing operation, but is operated during the non-fixing operation and during the rotation of the oil application roller. The invention of claim 3 is
2. The apparatus according to claim 1, wherein the pressure varying unit varies a contact pressure of the contact portion on the surface of the application roller in a state where the application roller is rotated in a reverse direction after the fixing operation is completed. Oil application device. If the application roller is rotated in the reverse direction and the contact pressure is varied after the fixing operation is completed, foreign matter such as paper dust adhered to the contact portion of the regulating means is easily peeled off. For this reason, after the end of the fixing operation,
The contact pressure is varied while the application roller is rotated in the reverse direction. Note that, in this case, the central pressure of the pressure fluctuation is set lower than the normal contact pressure so that the regulating means provided so as to abut in the counter-rotating direction of the application roller being reversed does not damage the surface of the application roller. It is desirable to set it to a lower side, and it is also desirable to set the maximum pressure of the pressure fluctuation to a side lower than the normal contact pressure.

According to a fourth aspect of the present invention, in the first aspect, an oil leveling member that contacts the pressure roller at a position downstream of the temperature detection position of the pressure roller forming a pair with the fixing roller in the rotation direction. An oil application device having a roller. In the fixing device, since the toner image formed on the upper surface of the recording paper is fixed, it is usually sufficient to apply oil (release agent) only to the upper fixing roller, but at the time of fixing the second surface of the duplex printing. In some cases, the first-fixed toner image on the first surface may be transferred to the surface of the lower fixing roller due to heat at the time of fixing the second surface. Therefore, the oil is evenly applied to the surface of the lower fixing roller (= the pressure roller forming a pair with the fixing roller) using the oil leveling roller. The invention according to claim 5 is the oil application device according to claim 4, wherein the surface layer of the oil leveling roller is made of a material having a function of retaining oil. The oil leveling roller is a roller that stores oil transferred from the upper fixing roller to the lower fixing roller and then uniformly applies the oil to the surface of the lower fixing roller. Therefore, a function of impregnating and holding oil is required. As such a material, for example, a silicon sponge can be used. According to a sixth aspect of the present invention, in the fourth or fifth aspect, during the period in which the pressure variable unit is not performing the fixing operation and the application roller is rotating, the contact portion contacts the surface of the application roller while the application roller is rotating. The contact pressure is varied, and the oil leveling roller performs the fixing operation of the image on the second side in a mode in which images are formed on both sides of the recording paper during a period in which the pressure varying means varies the contact pressure. The oil application device is characterized in that the oil application device is rotated during a certain period. For the reason described in the configuration of the second aspect, the pressure variable unit is operated during the non-fixing operation period and during the rotation of the oil application roller. During this pressure change, foreign matter such as paper powder adhering to the contact portion of the regulating means may again enter the oil on the surface of the application roller and be transferred to the lower fixing roller via the upper fixing roller.
Therefore, the leveling roller is rotated during the variable pressure period so that the foreign matter such as the paper dust does not adhere to the leveling roller. Also, the leveling roller is used to heat the image on the second side of the double-sided print due to the heat of the image, and fix the first fixed image on the first side.
In order to prevent the toner image on the surface from being transferred to the surface of the lower fixing roller, oil is supplied to the lower fixing roller when fixing the image on the second surface. It rotates during the fixing operation period.

[0010]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a longitudinal section of the oil application device of the embodiment. In addition, the hatched lines indicating the cross section are omitted, arrows indicating the rotation directions of the respective rollers, broken lines indicating the oil application device, and the like are described.

(1) Fixing device: Oil applying device 3 shown
Is an electrophotographic image forming apparatus (copier, printer,
Facsimile). The fixing device is a device that performs an image fixing process by thermocompression by passing a recording paper onto which a toner image has been transferred through a nip between the upper fixing roller 1 and the lower fixing roller 2. In the figure, 13, 13
Is a thermistor for detecting the surface temperature of the fixing rollers 1 and 2, 14 is a cleaning roller for cleaning the surface of the upper fixing roller 1, and 16 is a device for separating the recording paper after image fixing from the upper fixing roller 1. Reference numeral 15 denotes a guide for introducing recording paper on which a toner image is formed by an electrophotographic method into a fixing device, and 17 denotes a guide for leading out the recording paper after image fixing. Reference numeral 20 denotes a leveling roller having a surface layer made of silicon sponge. Side).

Driving means (driving source / driving force transmission mechanism) for rotating the upper fixing roller 1 and the lower fixing roller 2 are known. Further, a temperature control for controlling a heater (not shown) in the upper fixing roller 1 based on a temperature detected by the thermistor 13 (for example, on / off control) is also known. Therefore, their description is omitted. These are shown in FIG.
The driving unit of the fixing device is collectively shown.

(2) Oil applicator: The oil applicator shown by the dashed frame 3 has a part of its peripheral surface immersed in oil (silicone oil, release agent) 19 in an oil tank 18 and is directed in the direction of the arrow. A rotating drawing roller 6, a supply roller 5 pressed against the drawing roller 6 and rotated in the direction of the arrow, and an arrow direction pressed against the supply roller 5 and pressed against the fixing upper roller 1 to be applied with oil. And an application roller 4 that is rotated. Pressure contact between the application roller 4 and the upper fixing roller 1 is realized by displacing the oil application device 3 to the left in the drawing. The figure shows a state in which the application roller 4 and the upper fixing roller 1 are pressed against each other. On the other hand, when the application roller 4 is separated from the upper fixing roller 1, the oil application device 3 is displaced rightward in the figure.

Driving means (driving source / driving force transmitting mechanism / in FIG. 2 (a), shown as a "driving unit of the application roller") for rotating each of the rollers 6, 5, 4 in the directions shown. And the driving means (driving source / driving force transmission mechanism) for displacing (pressing / separating) the oil application device 3 as described above are well-known, and therefore description thereof is omitted. In the above configuration, a configuration in which a single roller is used as the pumping roller 6 and the supply roller 5 may also be used.

The oil 19 in the oil tank 18 is carried on the peripheral surface of the pumping roller 6 and then transferred onto the peripheral surface of the supply roller 5 and carried on the peripheral surface. And carried on the peripheral surface. The amount of oil on the peripheral surface of the application roller 4 is regulated to a constant amount by the regulating blade 7. The material of the peripheral surfaces of the rollers 6, 5, and 4 that carry the oil and the principle of the oil being carried on the peripheral surfaces of the rollers 6, 5, and 4 are well-known, and thus description thereof is omitted.

(3) Restriction means: The restriction means for restricting the amount of oil carried on the surface of the application roller 4 to a predetermined amount is a restriction blade 7 whose front end is pressed against the surface of the application roller 4.
A spring 8 for applying a biasing force to the regulating blade, a lever 9 for varying the tension of the spring 8, a gear 10 integral with the lever 9, a gear 11 meshing with the gear 10, and a gear 11
And a motor 12 for applying a driving force to the motor.

The regulating blade 7 is a plate made of SUS (stainless steel) in the present apparatus. The regulating blade 7 is integrally supported by a support member 7b.
b is rotatably supported by a pin 7a protruding from a support plate (not shown) of the casing in a direction perpendicular to the paper surface. For this reason, when the rear end side of the support member 7b is pulled upward in the drawing by the spring 8, the regulating blade 7 rotates about the pin 7a as a support shaft, and the front end portion thereof comes into pressure contact with the surface of the application roller 4. . In addition, when the force of the spring 8 pulling the rear end side of the support member 7b is weakened, the above-described pressing force is also weakened.

One end of the spring 8 is connected to the rear end of the support member 7b, and the other end is connected to a pin 9a at the tip of the lever 9. The base of the lever 9 is provided integrally with the gear 10 on the front side of the gear 10, and the gear 10 is rotated by a pin 10a protruding from a support plate (not shown) of the casing in a direction perpendicular to the plane of the drawing. Supported as possible. For this reason, when the gear 10 rotates counterclockwise in the figure, the spring 8 pulls the support member 7b upward in the figure, and the force of the leading end of the regulating blade 7 pressing the surface of the application roller 4 is pressed. Strengthen. Conversely, when the gear 10 rotates clockwise in the figure, the force of the spring 8 pulling the support member 7b upward in the figure is weakened, and the force of the tip of the regulating blade 7 pressing the surface of the application roller 4 is also increased. Weakens.

The gear 10 is meshed with a gear 11, and the gear 11 is rotatably supported by a pin (not shown) protruding from a support plate (not shown) of the casing in a direction perpendicular to the plane of the drawing. . The gear 11 has a motor 12
The rotational force (forward / reverse rotation) is transmitted from the motor through a driving force transmission mechanism (not shown). The motor 12 is a member that constitutes a part of a driving section of the variable pressure mechanism shown in FIG.

Therefore, when the motor 12 rotates in the forward direction (forward rotation), the gear 11 to which the driving force has been transmitted rotates clockwise in the drawing, whereby the gear 10 rotates counterclockwise. As described above, the force at which the tip of the regulating blade 7 presses against the surface of the application roller 4 is increased. Also,
When the motor 12 rotates in the reverse direction (reverse rotation), the gear 11 to which the driving force is transmitted rotates in the counterclockwise direction in the figure, whereby the gear 10 rotates in the clockwise direction, as described above. The force with which the tip of the regulating blade 7 presses against the surface of the application roller 4 is reduced. Instead of the forward / reverse rotation of the motor 12, a well-known member for switching the rotation direction of the gear 11 at an appropriate timing is provided at an appropriate position of a driving force transmission mechanism from the motor 12 to the gear 11. The above-described operation may be realized without switching the rotation direction of 12. In the following description, the forward / reverse rotation of the motor 12 includes such a case.

(4) Variable pressure operation: An operation (variable pressure operation) in which the tip of the regulating blade 7 changes the pressure applied to the surface of the application roller 4 will be described with reference to FIG.
The pressure variable operation is an operation realized by the forward / reverse rotation of the motor 12 as described above. The normal rotation / reverse rotation of the motor 12 is realized by the control unit that controls the image forming sequence issues appropriate instructions to the drive unit of the pressure variable mechanism at the timing described below.

FIG. 3 (a) shows the timing for performing the variable pressure operation during the image forming sequence. As shown in the drawing, during the period in which the fixing operation is not being performed and the application roller 4 is rotating, the motor 12 is rotated forward / reversely to apply the pressure contact applied from the tip of the regulating blade 7 to the surface of the application roller 4. Vary the force. The reason for avoiding the fixing operation period is that if the pressure is changed during the fixing operation, the thickness of the oil layer on the surface of the application roller is likely to be uneven, and the recorded image is likely to be defective. The reason why the pressure is changed during the rotation period of the application roller is that when a small amount of foreign matter such as paper dust adhered to the tip of the regulating blade 7 is peeled off due to the pressure change, the application roller 4 This is because it is easy to be spilled into the oil layer on the surface.

FIG. 3B shows the timing when the variable pressure operation is performed during the non-image forming operation. As shown in the drawing, the application roller 4 is rotated independently of the image forming sequence, and the motor 12 is rotated forward / reverse during the rotation period, and is applied to the surface of the application roller 4 from the tip of the regulating blade 7. To vary the pressing force. The variable pressure operation in the present invention may be executed independently of the image forming sequence.

FIG. 3C shows the timing when the variable pressure operation is performed after the end of the image forming operation. As shown in the drawing, after the fixing operation has been completed, the regulating blade 7 is rotated in the reverse direction (counterclockwise in FIG. 1).
The pressure contact force applied to the surface of the application roller 4 from the tip of the roller is varied. The reason why the application roller 4 is rotated in the reverse direction immediately after the end of the fixing operation is that foreign matters such as paper dust adhered to the tip of the regulating blade 7 are easily peeled off by the fixing operation. If the central pressure of the pressure fluctuation is set to a side lower than the normal contact pressure, the regulating blade 7
Can be prevented from damaging the surface of the application roller 4.

(5) Smoothing roller 20 and variable pressure operation: variable pressure period at the tip of regulating blade 7 and smoothing roller 2
FIG. 2 shows the relationship between the pressure welding and the pressure releasing timing of 0.
This will be described with reference to FIG. As described above, the leveling roller 20 is a roller provided on the downstream side of the thermistor 13 so that the surface layer portion is formed of silicon sponge and can be pressed against / released from the peripheral surface of the lower fixing roller 2. The function of temporarily holding the oil transferred from the oil application roller 4 to the lower fixing roller 2 via the upper fixing roller 1 and the function of uniformly applying the temporarily held oil to the surface of the lower fixing roller 2 are provided. Play.

As shown in the figure, during the pressure variable period and during the fixing operation of the second side of the double-sided printing, the leveling roller 20 is used.
To rotate. The reason is as follows. In FIG. 2A, the rotation of the leveling roller 20 is performed by issuing an instruction from the control unit to the driving unit of the fixing device.

That is, for the above-described reason, the variable pressure operation in the image forming sequence is executed during a period other than the fixing operation period and during the rotation of the oil application roller 4. If foreign matter, such as paper powder, adhering to the tip of the regulating blade 7 again enters the oil on the surface of the application roller due to the above-described pressure fluctuation, the foreign matter may be transferred to the lower fixing roller 2 via the upper fixing roller 1. is there. For this reason, during the above variable pressure period,
The leveling roller 20 is rotated so that the foreign matter does not adhere to the leveling roller 20. Further, at the time of fixing the image on the second surface of the double-sided printing, oil is applied to the surface of the lower fixing roller 2 in order to prevent the toner image of the first fixed surface from being transferred to the surface of the lower fixing roller. The leveling roller 20 needs to be supplied, and the smoothing roller 20 is rotated during this period.

[0028]

According to the present invention, in a pumping type oil applying apparatus, the regulating means for regulating the oil on the surface of the oil applying roller contacts the surface of the applying roller to reduce the amount of oil carried on the surface by a predetermined amount. And a pressure varying means for varying the pressure at which the contact portion of the regulating member comes into contact with the surface of the application roller. Force can be varied, and foreign matter such as paper dust can be prevented from adhering to the contact portion. Further, even when foreign matter such as paper dust adheres, the adhered foreign matter such as paper powder can be peeled off from the contact portion by the above-described pressure fluctuation and can be again immersed in oil on the surface of the application roller. It is possible to prevent the amount of foreign matter, such as paper dust, from becoming excessively large.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a configuration of an oil application device according to an embodiment.

2A is a block diagram showing a configuration of a control unit of the apparatus shown in FIG. 1, and FIG. 2B is a timing chart showing a relationship between a variable pressure operation period and a rotation period of an oil leveling roller.

3A and 3B show operation timings of the variable pressure mechanism of the apparatus of FIG. 1, wherein FIG. 3A shows an operation during an image forming sequence, FIG. 3B shows an operation during a non-image forming operation, and FIG. The operation of is described below.

FIG. 4 is a cross-sectional view showing a configuration example of a conventional oil application device.

[Description of Signs] 4 Oil application roller 7 Regulator blade 8 Spring 9 Lever 10 Gear 11 Gear 12 Motor

 ──────────────────────────────────────────────────続 き Continued on front page F term (reference) 2H027 ED25 FA13 2H033 BA43 BA44 BA45 BA46 4F040 AA02 AB08 AC01 CB02 CB33 DA04 DA12 DA16 9A001 BB06 HH23 KK42

Claims (6)

[Claims] 1. A pump roller partially immersed in oil in a tank, a supply roller pressed against the pump roller, and a coating roller pressed against the supply roller and pressed against a fixing roller to be coated with oil. A roller, and the oil in the tank is carried on the surface of the application roller via the surface of the pumping roller and the surface of the supply roller, and the amount of the carried is regulated by regulating means. A regulating member having a contact portion that contacts a surface of the applying roller and regulates an amount of oil carried on the surface to a predetermined amount; An oil applying device, comprising: a pressure varying unit that varies a pressure at which the unit contacts the surface of the application roller. 2. The pressure changing unit according to claim 1, wherein the pressure changing unit changes a contact pressure of the contact portion on a surface of the application roller during a period in which a fixing operation is not performed and the application roller is rotating. An oil applicator, characterized in that: 3. The pressure changing device according to claim 1, wherein the pressure changing unit changes the contact pressure of the contact portion to the surface of the application roller while the application roller is rotated in a reverse direction after the fixing operation is completed. An oil applicator, which is variable. 4. An oil leveling roller according to claim 1, further comprising an oil leveling roller abutting on the pressure roller at a position downstream of the temperature detection position of the pressure roller forming a pair with the fixing roller in the rotation direction. An oil application device characterized by the above-mentioned. 5. The oil application device according to claim 4, wherein a surface layer of the oil leveling roller is made of a material having a function of retaining oil. 6. The application roller surface of the contact portion according to claim 4, wherein the pressure variable unit is configured to perform a fixing operation while the application operation is not being performed and the application roller is rotating. The oil leveling roller performs a period during which the pressure varying unit varies the contact pressure, and a fixing operation of an image on the second surface in a mode in which images are formed on both sides of the recording paper. The oil application device is rotated during a period when the oil is applied.