JP2007033762A - Fixing device and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fixing device and an image forming device of low price and high reliability which prevents poor oil supply. <P>SOLUTION: The fixing device has a movable oil sucking body 10 which sucks releasing oil in an oil tank 5, an oil supply roller which contacts the movable oil sucking body 10 and an oil application roller 8 which contacts the oil supply roller 7 and supplies the releasing oil to a fixing roller 2 or a fixing belt 3 and the movable oil sucking body 10 moves approximately in the vertical direction of an axis direction of the oil supply roller. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a fixing device mounted on an electrostatic recording image forming apparatus such as a copying machine, a facsimile machine, or a printer, and an image forming apparatus.

In the market for image forming apparatuses such as printers, copiers, and facsimiles, there is an increasing demand for high reliability and low cost. In order to provide a space-saving image forming apparatus that satisfies all these requirements, it is an important issue to examine the layout by function.
In general, in an image forming apparatus, a toner image is formed on an image carrier such as a photoreceptor or an intermediate transfer member by a toner image forming process, and the toner image is transferred from the image carrier to a recording medium such as a supplied transfer paper or OHP film. After the toner image is fixed on the recording medium by the fixing device, the recording medium is discharged out of the device.
The fixing device has a heating and fixing method in which a toner image transferred to a transfer paper is passed between heated roller pairs so that the toner is melted by heat and pressure and penetrates into the fiber of the paper to fix the toner image. Many have been adopted.
At that time, in order to prevent so-called toner offset that occurs in the fixing roller, it is common to apply Teflon (registered trademark) coating or coating on the surface of the fixing roller to improve the releasability of the toner. In order to prevent the offset, a technique of applying and supplying so-called fixing oil typified by silicon oil to the surface of the fixing roller is widely adopted. Since a number of mechanisms are employed for the oil application mechanism (oil supply device) to the surface of the fixing roller, description of a representative example is omitted.
However, in almost all mechanisms, the offset toner on the fixing roller is not completely lost, and in the case of an oil supply device that is in contact with the fixing roller, a part of the offset toner is transferred to and adhered to the oil supply device.
Although the offset toner is melted on the fixing roller, when it leaves the fixing roller, it is solidified because it drops below its melting point, and when this solidified material accumulates on the oil supply device, the oil supply at the deposited location is Stagnation, offset toner is increased, contamination in the fixing device is promoted, and image quality is deteriorated.
Therefore, in the case of the oil supply device that is in contact with the fixing roller, once the oil application failure occurs due to the adhesion of the offset toner, the offset toner is cumulatively increased to contaminate the oil supply device, and the oil supply failure is further deteriorated. It has a problem that becomes a vicious circle, and hinders high reliability of the fixing device.
Patent Document 1 proposes a mechanism for scraping off offset toner by bringing a counter blade into contact with an oil supply roller. In addition, as a technique for cleaning the offset toner that has adhered to other members by the fixing roller or the transition, Patent Document 2 discloses a technique that moves the contaminated part of the web cleaning unit to suppress the reattachment of contaminants. Has been proposed.
JP 2003-122168 A JP 2002-278347 A

However, in the case of Patent Document 1, it is necessary to select a high-performance material excellent in heat resistance, wear resistance, and oil swell resistance, such as silicon rubber, as a counter blade. It was difficult.
Further, in Patent Document 2, when oil is applied by impregnating a web sheet with oil, the web sheet is thin, so that a sufficient amount of oil cannot be held and only a small amount of oil can be applied. In addition, when the oil supply system and the web cleaning system are arranged separately, the web sheet absorbs the oil that transitions through the surface of the fixing roller, resulting in a problem that the oil consumption increases. I had it.
SUMMARY OF THE INVENTION An object of the present invention is to provide an inexpensive and highly reliable fixing device and image forming apparatus that prevent oil supply failure.

To achieve the above object, an invention according to claim 1 is directed to an oil absorber that absorbs release oil in an oil tank, an oil supply roller that contacts the oil absorber, a contact roller that contacts the oil supply roller, and a fixing roller. Alternatively, the main feature is a fixing device that includes an oil application roller that supplies release oil to the fixing belt, and the oil absorber is provided so as to be movable in a direction substantially perpendicular to the axial direction of the oil supply roller.
According to a second aspect of the present invention, in the fixing device according to the first aspect, as the oil absorber, in addition to a fixed oil absorber immersed in an oil tank, a thin sheet-like movable oil that can be wound around a shaft. The main feature is a fixing device in which an absorber is provided and the movable oil absorber is brought into contact with the oil supply roller.
According to a third aspect of the present invention, an image forming apparatus equipped with the fixing device according to the first or second aspect is the main feature.

  The present invention relates to an oil absorber that absorbs release oil in an oil tank, an oil supply roller that contacts the oil absorber, an oil application that contacts the oil supply roller and supplies the release oil to a fixing roller or fixing belt Since the oil absorber is provided so as to be movable in a direction substantially perpendicular to the axial direction of the oil supply roller, a large amount of offset toner accumulates in the vicinity of the contact portion between the oil absorber and the oil supply roller. If the oil absorber is moved before it becomes, it is possible to avoid a shortage of oil supply caused by the accumulated offset toner.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a configuration diagram of a fixing device according to an embodiment of the present invention. This fixing device is mounted on an image forming apparatus having a known structure. The fixing device includes a heating roller 1 having a built-in heat source, a fixing roller 2 having a surface layer formed of silicon sponge or silicone rubber, a fixing belt 3 that is stretched around the heating roller 1, the fixing roller 2, and a roller (not shown), and rotates. In order to form a fixing nip, a pressure roller 4 that presses the fixing roller 2 through the fixing belt 3 is provided.
Similarly, the fixing device includes an oil tank 5 that stores oil to be supplied, a felt-type oil absorber (fixed oil absorber) 6 that pumps oil from the oil tank 5 to the movable oil absorber, and oil absorption. An oil supply roller 7 for delivering oil from the body 6 is provided. The oil supply roller 7 is pressed against the oil application roller 8 by a spring mechanism (not shown), and is driven by the rotation of the oil application roller 8 by a frictional force with the oil application roller 8.
The oil application roller 8 is a roller that delivers oil onto the fixing belt 3, and is pressed against the fixing roller 2 and the fixing belt 3 by a spring mechanism (not shown), and due to the frictional force with the fixing belt 3, the fixing belt 3. Driven by the rotation of
Similarly, the fixing device includes a sheet metal member 9 that presses the oil absorber 6 against the oil supply roller 7 in order to equalize the oil supply amount in the axial direction. The sheet metal member 9 is always pressed toward the oil supply roller 7 by a spring mechanism.
Similarly, the fixing device includes a movable oil absorber 10 that is movable when oil is supplied to the oil supply roller 7. The movable oil absorber 10 is a thin sheet-like member, the end of which is fixed to the shaft 11, and the portion of the movable oil absorber 10 that is sandwiched between the nip between the oil absorber 6 and the oil supply roller 7 is the shaft 11. When the is driven and rotated, it moves so as to be wound up in the upward direction. Reference numeral 12 denotes a rotatable supply shaft around which the movable oil absorber 10 is wound in order to supply the movable oil absorber 10.
Similarly, the fixing device includes a fixing nip entry guide 13 for the transfer paper, a fixing nip outlet guide 14 (14a, 14b), and a case 15. Further, a fixing cleaning roller 16 is provided which is pressed by the fixing roller 2 and the fixing belt 3, rotates following the fixing roller 2 and the fixing belt 3, and adsorbs offset toner on the surface of the fixing belt 3.
Reference numeral 17 denotes a transfer sheet passing through the fixing nip, and is conveyed from the bottom to the top. Reference numeral 18 denotes an unfixed toner image transferred to the transfer paper 17 by a transfer device (not shown), and 19 denotes a toner image fixed to the transfer paper 17 schematically.

Next, the operation will be described. When the oil runs on the surface of the fixing belt 3 while abundantly present, the oil lubrication action on the surface of the fixing belt 3 reduces the friction coefficient μ between the oil application roller 8 and the fixing belt 3, and the oil The application roller 8 is set to a pressure setting that does not follow rotation. Since the oil application roller 8 does not rotate, excessive oil application is not performed on the surface of the fixing belt 3.
When the transfer paper 17 passes through the fixing nip, the oil on the surface of the fixing belt 3 transits to the transfer paper 17 and the amount of oil on the surface of the fixing belt 3 decreases, and the friction coefficient μ between the oil application roller 8 and the fixing belt 3 increases. The oil application roller 8 is driven by the frictional force.
When the oil application roller 8 rotates, the oil transitions from the oil supply roller 7 to the surface of the oil application roller 8, and the amount of oil on the surface of the oil supply roller 7 decreases, so that the friction between the oil supply roller 7 and the oil application roller 8 occurs. The coefficient μ increases and the oil supply roller 7 is driven by the frictional force. As the oil supply roller 7 rotates, the oil in the oil absorber 6 is supplied to the surface of the oil supply roller 7 via the movable oil absorber 10.
As this operation continues, the amount of oil on the surface of the fixing belt 3 gradually increases. When the oil application roller 8 is supplied to the fixing belt 3 with an amount of oil that has a friction coefficient μ that cannot rotate the oil application roller 8, the oil supply from the oil application roller 8 to the fixing belt 3 is stopped. In an actual printing state, this operation is cycled so that oil application to the surface of the fixing belt 3 is not delayed.
Most of the offset toner that has shifted to the fixing belt 3 side adheres to the surface of the fixing cleaning roller 16 and is cleaned, but part of the offset toner slips through and adheres to the surface of the oil application roller 8. A part of the toner further adheres to the surface of the oil supply roller 7 and accumulates in the vicinity of the contact point between the movable oil absorber 10 and the oil supply roller 7 (deposition offset toner 20).
The accumulated offset toner 20 cannot move anywhere and stays there, hindering the delivery of oil from the movable oil absorber 10 to the oil supply roller 7, or the pattern of the deposit becomes an oil streak and becomes a fixing belt. 3 reaches the surface and causes streaks in the fixed image.

In the present invention, before the accumulated offset toner 20 is accumulated excessively, the shaft 11 is rotated and the movable oil absorber 10 is wound up, so that the new surface of the movable oil absorber 10 (the oil supply roller 7 is in contact). (The unused surface on the upstream side in the winding direction) can be brought into contact with the oil supply roller 7, and oil supply failure due to the accumulated offset toner 20 can be avoided, further contamination of the movable oil absorber 10, or oil Oil streaks in the image due to supply failure can be prevented.
Further, when the movable oil absorber 10 is not disposed, a drive mechanism for moving the oil absorber 6 in the upward direction in the figure before deposits are excessively accumulated in the oil absorber 6 fixed to the sheet metal 9 can be provided. That's fine.
As described above, when there is sufficient oil on the surface of the fixing belt 3, the oil supply roller 7, and the oil application roller 8, the friction coefficient μ becomes low, so that the oil supply roller 7 and the oil application roller 8 are set to hardly rotate. It is. Therefore, if a rotational speed detection sensor is arranged on either shaft of the oil supply roller 7 or the oil application roller 8, the oil is sufficiently supplied if the rotational speed per hour is low when paper is not passed. If the number of revolutions per hour is high, the control means (not shown) can determine that the oil supply is stagnant.
A control mode in which the shaft 11 is driven before deposits are accumulated excessively, and the movable oil absorber 10 is moved by a fixed amount in relation to the number of normal prints and the amount of toner consumed in the toner image forming system upstream of the fixing device. In general, the rotational speed of the oil supply roller 7 and the oil application roller 8 per hour is used as an identification standard, and when the rotational speed per time exceeds a threshold value, an oil supply failure has occurred. If the control means determines and the control configuration is such that the movable oil absorber 10 is moved by a certain amount, the reliability is further improved, and even if oil streaks occur in the image, it can be restored.

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

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Heating roller 2 Fixing roller 3 Fixing belt 4 Pressure roller 5 Oil tank 6 Oil absorber 7 Oil supply roller 8 Oil application roller 9 Sheet metal 10 Movable oil absorber 11 Shaft 12 which winds a movable oil absorber Wound shaft 13 Fixing nip entry guide 14 Fixing nip exit guide 15 Case 16 Fixing cleaning roller 17 Transfer paper passing through fixing nip

Claims (3)

  An oil absorber that absorbs release oil in the oil tank; an oil supply roller that contacts the oil absorber; an oil application roller that contacts the oil supply roller and supplies the release oil to the fixing roller or fixing belt; And the oil absorber is provided so as to be movable in a direction substantially orthogonal to the axial direction of the oil supply roller.   2. The fixing device according to claim 1, wherein a thin sheet-like movable oil absorber that can be wound around a shaft is provided as the oil absorber, in addition to the fixed oil absorber immersed in the oil tank. A fixing device, wherein an absorber is brought into contact with the oil supply roller.   An image forming apparatus comprising the fixing device according to claim 1.

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