JP2000089602A - Peeling device and fixing device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent trouble in image quality caused by the contact of an image supporting body to which a toner image is transferred with a peeling member peeling the image supporting body from a fixing member by electrifying the peeling member to have the same polarity as the electrification polarity of the image supporting body. SOLUTION: This fixing device 33 is provided with a peeling pawl 54 having a wedged cross section as the peeling member peeling the transfer paper from a heating roll 33a near the exit of a press-contact part 53 between the roll 33a and a pressure roll 33b. The pawl 54 is arranged in a non-contact state so that its tip may form a small gap on the surface of the roll 33a, or arranged so that it may come in contact therewith by very weak force. The voltage having the same polarity as the electrification polarity of the transfer paper is applied to the pawl 54 by a power source 55 for electrifying the pawl 54. The pawl 54 is electrified to the same polarity as the transfer paper. It is desirable that the material of the pawl 54 is dielectric, and material having a large dielectric constant such as balium titanate or cesium niobate is used therefor.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fixing device used in an image forming apparatus to which an electrophotographic method is applied, such as an electrophotographic copying machine or a printer, and a peeling device used in the fixing device. The present invention relates to a peeling device capable of reliably preventing an image quality failure due to contact between an image support onto which an image has been transferred and a peeling member, and a fixing device using the same.

[0002]

2. Description of the Related Art Conventionally, as a fixing device used in an image forming apparatus to which an electrophotographic system such as an electrophotographic copying machine or a printer is applied, for example, a heating roll having a heating source therein and a pressure roll are provided. Are brought into pressure contact with each other, and an image support such as transfer paper on which the unfixed toner image is transferred is conveyed to a pressure contact portion (nip portion) between the heating roll and the pressure roll, and passes through a nip portion between the two rolls. During this operation, the unfixed toner image is fixed on the image support by heat and pressure.

In such a fixing device, a heating roll and a pressure roll are rotated while being pressed against each other, and an image support having an unfixed toner image is passed through a nip portion between the two rolls. Unless any measures are taken when fixing the unfixed toner image on the image support by the pressure, the image support heats and melts, and the adhesive action of the toner causes a wrap around the surface of the heating roll to cause a jam. There is a fear that the device becomes unusable.

Therefore, in the fixing device configured as described above, the thickness of the elastic layer provided on the surface side of the heating roll is set to be large in order to surely separate the transfer paper from the surface of the heating roll. By pressing a pressure roll against a heating roll, the elastic layer on the surface of the heating roll is deformed into a concave shape, and a self-stripping method in which an image support passing through a nip portion of both rolls is separated by itself, or a nip. A method is used in which a peeling claw is provided near the exit of the unit, and the image support is forcibly peeled from the surface of the heating roll by the peeling claw.

[0005]

However, the prior art described above has the following problems. In other words, in the former fixing device employing the self-stripping method, it is necessary to set the thickness of the elastic layer provided on the surface side of the heating roll to be large. Unfortunately, there is a problem that the warm-up time until the surface of the heating roll is heated to a predetermined temperature becomes long.

[0006] In the latter type of fixing device using a separation claw, when the image support is separated from the heating roll by the separation claw, the separation claw and the image support are rubbed.
A problem that a part of the peeling claw comes into contact with the toner image immediately after being fixed on the image support and disturbs the uncured toner image immediately after being fixed, which may cause an image quality failure. Had a point.

Therefore, as a means for solving such a problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 61-205968, a fixing device comprising a pair of rollers and at least one of which has a heating means has two When the paper passes between the rollers, the paper is electrostatically attracted to the roller on the side not in contact with the toner image, and the paper is curved along the surface thereof. It is configured to be separated from the roller. As a means for electrostatically adsorbing the paper to the roller that does not contact the toner image, for example, a corotron is used.

However, in the case of the technique disclosed in Japanese Patent Application Laid-Open No. 61-205968, the paper is electrostatically attracted to the roller that does not come into contact with the toner image. It is necessary to provide a corona charger such as a corotron, and the surface of the pressure roll is exposed to corona discharge.Therefore, there is a problem with the life of the roll surface. Problem.

Accordingly, the present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to provide an image supporting apparatus without taking measures such as charging the roll surface on the pressing side. The peeling device and the use of the peeling device which can surely prevent the occurrence of an image quality failure due to the contact between the peeling member and the image support to which the toner image has been transferred, as well as being able to reliably peel the body from the roll. To provide an improved fixing device.

[0010]

According to a first aspect of the present invention, there is provided a peeling device for peeling an image support on which a toner image is fixed from a pair of fixing members at least one of which is a roll. In the vicinity of the exit of the press-contact portion of the fixing member, a peeling member for peeling the image support from the fixing member formed of a roll is provided, and charging means for charging the peeling member to the same polarity as the charging polarity of the image support is provided. It is what was constituted.

According to a second aspect of the present invention, there is provided a fixing device for fixing a toner image on an image support by conveying while at least one of the pair of fixing members is formed by a pair of rolls. In the vicinity of the exit of the pressure contact portion of the fixing member, a peeling member for peeling the image support from the fixing member made of a roll is provided, and a charging unit for charging the peeling member to the same polarity as the charging polarity of the image support is provided. Is a fixing device.

Further, the invention according to claim 3 is the fixing device according to claim 2, wherein the charging means also serves as a means for charging a fixing member formed of a roll.

Further, the invention according to a fourth aspect is the fixing device according to the second or third aspect, wherein the peeling member is grounded via a rectifying element.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings.

FIG. 2 shows a digital copying machine as an image forming apparatus to which the fixing device according to the present invention is applied.

In FIG. 2, reference numeral 1 denotes a main body of the digital copying machine, and an automatic document feeder for automatically feeding the originals 2 in a state of being separated one by one is provided above the digital copying machine main body 1. An (ADF) 3 and an image reading device 4 for reading an image of the document 2 conveyed by the automatic document conveying device 3 are provided. The image reading device 4 illuminates a document 2 placed on a platen glass 5 with a light source 6, and reflects a reflected light image from the document 2 on a full-rate mirror 7.
And an image reading element 11 such as a CCD through a reduction optical system including half rate mirrors 8 and 9 and a lens 10.
It is configured to scan and expose on top.

The image information of the document 2 read by the image reading device 4 is stored in a temporary storage device (not shown), and an IPS (Image Process) as needed.
After a predetermined image processing is performed by the ing system 12, a ROS (Raster Output Scanner) is performed according to the image information on which the image processing is performed.
r) 13, the photosensitive drum 14 as an image carrier
Image exposure is performed thereon to form an electrostatic latent image. R above
The OS 13 includes a semiconductor laser 15 that emits a laser beam according to image information, and a polygon mirror 1 that scans a laser beam emitted from the semiconductor laser 15.
6 and mirrors 17 and 18 for exposing the laser beam scanned by the polygon mirror 16 onto the photosensitive drum 14. Prior to the image exposure by the ROS 13, the photosensitive drum 14 is uniformly charged to a predetermined potential of a predetermined polarity (for example, a negative polarity) by a primary charger 19 composed of a scorotron, and as described above, The image of the document 2 is exposed by the ROS 13, and an electrostatic latent image is formed. The electrostatic latent image formed on the photosensitive drum 14 is developed by a developing device 20 as a developing unit to become a toner image. In the developing device 20, for example, a negatively charged toner having the same polarity as the charged polarity of the photosensitive drum 14 is used, and development is performed by a reversal developing method. However, the present invention is not limited to this.
The development may be performed by a regular development method using a positively charged toner having a polarity opposite to the charge polarity of the photosensitive drum 14. This toner image is transferred to the transfer charger 21
The transfer paper 22 to which the toner image has been transferred is transferred from the photosensitive drum 14 by the charge removal of the peeling charger 23, while being transferred onto the transfer paper 22 by the positive charge of. The transfer paper 22 to which the toner image is transferred from the photosensitive drum 14 is supplied by a paper feed roll 28 from one of a plurality of paper feed cassettes 24, 25, 26, and 27 provided inside the copying machine body 1. Rolled paper and transport roll 29
And the resist gate 31 via the pre-registration roll 30
And is stopped once. Then, the transfer paper 2
Reference numeral 2 denotes a resist roll 3 that passes through a resist gate 31 that opens in synchronization with a toner image formed on the surface of the photosensitive drum 14 and is disposed downstream of the resist gate 31.
2, the toner image is conveyed to the surface of the photosensitive drum 14 and, as described above, the toner image formed on the surface of the photosensitive drum 14 is transferred, and then is separated from the surface of the photosensitive drum 14.

The transfer paper 22 separated from the surface of the photosensitive drum 14 is transported to a fixing device 33 by a transfer material transport device transport device 50, and the toner is transferred onto the transfer paper 22 by the fixing device 33 by heat and pressure. The image is fixed. The transfer paper 22 on which the toner image is fixed is discharged by an outlet roll 34 of a fixing device 33 onto a discharge tray 36 outside the apparatus by a discharge roll 35 as it is in the case of normal single-sided copying. In the case of double-sided copying, the transfer sheet 22 having the toner image fixed on one side thereof is not discharged to the outside of the apparatus by the discharge roll 35, but the transport direction is changed downward by the reversing gate 37, and the three rolls are transferred. Is once conveyed to the reversing passage 40 by the tri-roll 38 and the reversing roll 39 pressed against each other. Then, the transfer paper 22 is conveyed to the two-sided passage 42 by the reversing roll 39 and the two-sided roll 41 which are reversed this time, and is once conveyed from the two-sided passage 42 to the registration gate 31 via the pre-registration roll 30. Stop, and as described above, the resist gate 31 and the resist roll 3
2, the toner image is conveyed in synchronism with the toner image on the photosensitive drum 14, and is transferred onto a discharge tray 36 by a discharge roll 35 after the toner image is transferred and fixed.

After the toner image transfer step is completed, the surface of the photoreceptor drum 14 is cleaned of residual toner and paper dust by a cleaning device 43 to prepare for the next image forming step.

FIG. 3 is an enlarged view of the image forming section of the digital copying machine constructed as described above.

In FIG. 3, reference numeral 14 denotes the photosensitive drum. As the photosensitive drum 14, for example, a photosensitive member using an organic photoconductive substance is used.
The photosensitive drum 14 is driven at a predetermined rotational speed along a direction indicated by an arrow A by a driving unit (not shown). The surface of the photosensitive drum 14 is uniformly charged to a predetermined potential by a primary charger 19 made of a scorotron or the like. Thereafter, on the surface of the photosensitive drum 14, the laser light LB is scanned and exposed according to the image information by the ROS 13 that performs image exposure based on the image information, and an electrostatic latent image is formed. The electrostatic latent image formed on the photosensitive drum 14 is
a to form a toner image. Further, the toner image formed on the surface of the photoconductor drum 14 is charged by the transfer auxiliary charger 44 and is auxiliary-charged.
29 and the resist roll 32, the photosensitive drum 1
Transfer paper 2 conveyed at a predetermined timing to the surface of
2 is transferred by the charging of the transfer charger 21. The transfer paper 22 to which the toner image has been transferred as described above is neutralized by a peeling charger 23, peeled off from the surface of the photosensitive drum 14, and is conveyed to the fixing device 33 by the conveying belt 51 of the paper conveying device 50. The toner image is fixed on the transfer paper 22 by heat and pressure by the heating roll 33a and the pressure roll 33b of the fixing device 33, and is discharged onto a discharge tray 36 provided outside the device. The cleaning device 43 removes residual toner and the like from the surface of the photosensitive drum 14 on which the transfer of the toner image has been completed, so that the surface is ready for the next image forming process. In the drawing, reference numeral 45 denotes a housing of the cleaning device, 46 denotes a cleaning brush, 47 denotes a cleaning blade, 48 denotes a film seal, and 49 denotes a collected toner conveying means.

FIG. 4 is a structural view showing the fixing device.

This fixing device 33 is, as shown in FIG.
It has a heating roller 33a having a heating source 52 inside, and a pressure roller 33b arranged to be in pressure contact with the heating roller 33a. The heating roller 33a and the pressure roller 33b are pressed against each other with a predetermined pressure,
The transfer paper 22 as an image support on which the toner image has been transferred from the surface of the photosensitive drum 14 is transported to the nip 53 between the rollers 33a and 33b.

The transfer sheet 22 carrying the unfixed toner image is melted by heat and pressure while passing through the nip 53 between the heating roller 33a and the pressure roller 33b. Then, the toner image is fixed on the transfer paper 22 to become a permanent image.

In this embodiment, a peeling member for peeling the image support from the fixing member formed of a roll is provided near the outlet of the pressure contact portion of the pair of fixing members, and the peeling member is charged with the image support. It is configured to provide charging means for charging to the same polarity as the polarity.

That is, in the fixing device 33 according to this embodiment, as shown in FIG. 1, the heating roll 3a is located near the exit of the pressure contact portion 53 between the heating roll 33a and the pressure roll 33b.
A separation claw 54 having a wedge-shaped cross section is provided as a separation member for separating the transfer sheet 22 from the transfer claw 3a.
4, the transfer paper 22 is forcibly peeled off from the surface of the heating roll 33a.

As shown in FIGS. 1 and 5, the peeling claw 54 is formed in a wedge-shaped cross section.
It is arranged in a non-contact state so as to form a slight gap on the surface of the heating roll 33a, or is arranged so as to contact with a very weak force. Further, a plurality of the peeling claws 54 are provided along the axial direction of the heating roll 33a, so that the transfer paper 22 can be reliably peeled from the surface of the heating roll 33a over the entire width thereof. I have. Further, a voltage of, for example, about 1 kV of a positive polarity having the same polarity as the charging polarity of the transfer paper 22 is applied to the peeling claw 54 by a power supply 55 for charging the peeling claw as a charging unit. Reference numeral 54 is configured to be charged to the same polarity as the transfer paper 22. The voltage applied to the peeling nail 54 by the peeling nail charging power supply 55 is applied to the peeling nail 54 when the image support is made of a material having a high dielectric constant such as an OHP sheet instead of the transfer sheet. A higher voltage than normal may be applied.

It is preferable to use a dielectric material as the material of the peeling claw 54 in order to prevent the charge from being released and to enable the peeling claw 54 to be charged at a low potential. As a material constituting the peeling claw 54, for example, barium titanate, strontium titanate, potassium niobate,
A material having a large dielectric constant, such as sodium niobate or cesium niobate, can be used.

In this embodiment, the pressure roll 3
A power supply 56 for applying a positive voltage having a polarity opposite to that of the toner transferred onto the transfer paper 22 to the metal core 33b ′
Is connected, and electrostatically attracts the toner image from the back side of the transfer paper 22 to prevent the toner image from being offset to the heating roll 33a. It is needless to say that the pressure roll 33b need not be charged in this way.

In the digital copying machine to which the fixing device according to this embodiment is applied in the above-described configuration, the image support is rolled without taking any means such as charging the roll surface on the pressure side in the following manner. As a matter of course, it is possible to surely remove the toner image from the image support due to the contact between the peeling member and the image support on which the toner image has been transferred.

That is, in a digital copying machine to which the fixing device according to this embodiment is applied, as shown in FIG.
At a predetermined timing, a toner image corresponding to the image of the original 2 is formed on the photosensitive drum 14, and the toner image is transferred to the transfer paper 2 by the positive charging of the transfer charger 21.
Transfer paper 22 onto which the toner image has been transferred
Is transported to the fixing device 33, and the fixing device 33 fixes the toner image on the transfer paper 22 by heat and pressure, thereby copying the image of the original 2.

In the fixing device 33, as shown in FIG. 3 and FIG.
After the transfer paper 22 carrying the unfixed toner image has passed through the nip portion 3b, when the leading end of the transfer paper 22 reaches the tip of the peeling claw 54 near the exit of the nip portion 53, the transfer paper 22 is heated by a heating roll. It is peeled from the surface of 33a by the peeling claw 54.

At this time, a positive voltage having a polarity opposite to the charging polarity of the toner is applied to the pressure roll 33b by the power source 56 in order to prevent the offset of the toner. The transfer paper 22 is again charged to a positive polarity with the opposite polarity to the toner. Then, as the transfer of the transfer paper 22 further proceeds, as shown in FIG. 6, the voltage applied to the separation claw 54 charged to the same polarity as that of the transfer paper 22 causes the transfer paper 22 and the separation claw 54 The electrostatic repulsion generated between them acts as a cushioning material,
Reduce the contact force between the transfer paper 22 and the peeling claw 54;
The transfer paper 22 can be peeled with a weak peeling force, and the peeling claw 54 can be prevented from rubbing the surface of the transfer paper 22. Therefore, the transfer paper 2
2 can be surely peeled off from the heating roll 33a, and the transfer paper 22 on which the toner image has been transferred.
It is possible to reliably prevent the occurrence of an image quality failure due to the contact between the release claw and the release claw 54.

Embodiments 2 to 4 FIGS. 7 to 9 show Embodiments 2, 3, and 4, respectively, of the present invention. The same parts as those in Embodiment 1 are denoted by the same reference numerals. In the second embodiment,
As shown in FIG. 7, the charging polarity of the transfer paper 22 is negative, and a negative voltage having the same polarity as the charging polarity of the transfer paper 22 is applied to the peeling claw 54 by the power supply 55. Have been.

In the third embodiment, as shown in FIG. 8, instead of applying a voltage to the peeling claw 54 by a power source, the peeling claw 54 is grounded via a diode 60, and the transfer generated in the transfer step is performed. The peeling claw 54 is configured to be charged to the positive polarity having the same polarity as the transfer paper 22 by using the charged charge of the paper 22. In this case, the power supply 55 is not required. However, even in the embodiment shown in FIG. 8, a power supply 55 is provided in parallel with the diode 60, the peeling claw 54 is once charged to a predetermined potential by the power supply 55, and then the power supply 55 is cut off. Peeling nail 54
May be maintained at a predetermined potential.

Further, the fourth embodiment is basically configured in the same manner as the third embodiment, except that the diode 6
The connection polarity of 0 is in the opposite direction, and the peeling claw 54 is charged to a negative polarity.

Embodiments 5 and 6 FIGS. 10 and 11 show Embodiments 5 and 6 of the present invention. In Embodiment 5, as shown in FIG. Instead of being formed of the above-described dielectric material, the main body 54a of the peeling claw 54 is made of a metal such as aluminum or stainless steel.
The dielectric thin film 54b described above may be deposited on the tip and the bottom of the device by any method so as to apply a predetermined voltage to the peeling claw body 54a.

In the sixth embodiment, as shown in FIG. 11, a MOS type S is provided between a metal main body 54a serving as an electrode of the peeling claw 54 and a dielectric thin film 54b serving as the peeling claw 43.
Like a semiconductor layer made of i (silicon) or the like, a charge leakage prevention layer 54c exhibiting characteristics as a diode may be provided.

The peeling claw 54 is connected to the heating roll 33.
A plurality of peeling claws 5 are not provided along the axial direction of a.
A baffle type in which 4 is a single plate may be used.

Seventh Embodiment FIG. 12 shows a seventh embodiment of the present invention. In the seventh embodiment, the presence or absence of passage of an image support near the nip portion 53 of the fixing device is not shown. A sensor is provided, and when the image support reaches the peeling nail, a voltage higher than normal is applied to the peeling nail 54 in a pulsed manner, and the other voltage is applied to a lower voltage. . Note that the voltage may be applied to the peeling claw 54 only when the image support reaches the peeling claw.

In controlling the potential applied to the peeling claw 54, it is preferable that a constant repulsive force acts between the image support 22 and the peeling claw 54. Therefore, a DC potential or some AC waveform is superimposed on the DC. A waveform is applied.

[0042]

As described above, according to the present invention, the image support can be surely peeled off from the roll without taking measures such as charging the roll surface on the pressure side. It is possible to provide a peeling device and a fixing device using the same, which can reliably prevent the occurrence of an image quality failure due to the contact between the image support on which the image has been transferred and the peeling member.

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a fixing device to which a peeling device according to a first embodiment of the present invention is applied;

FIG. 2 is a configuration diagram showing a digital copying machine to which the fixing device according to the present invention can be applied.

FIG. 3 is a configuration diagram illustrating an image forming unit of FIG. 2;

FIG. 4 is a configuration diagram showing a fixing device according to the first embodiment of the present invention.

FIG. 5 is a sectional view showing a peeling claw.

FIG. 6 is an explanatory view showing the operation of the peeling device.

FIG. 7 is a configuration diagram showing a fixing device to which a peeling device according to a second embodiment of the present invention is applied.

FIG. 8 is a configuration diagram showing a fixing device to which a peeling device according to Embodiment 3 of the present invention is applied.

FIG. 9 is a configuration diagram showing a fixing device to which a peeling device according to Embodiment 4 of the present invention is applied.

FIG. 10 is a configuration diagram showing a peeling device according to a fifth embodiment of the present invention.

FIG. 11 is a configuration diagram showing a peeling device according to a sixth embodiment of the present invention.

FIG. 12 is a graph showing an operation of a peeling device according to Embodiment 7 of the present invention.

[Explanation of symbols]

22: transfer paper (image support), 33: fixing device, 33
a: heating roll, 33b: pressure roll, 54: peeling nail,
55: Power supply.

Continued on the front page (72) Inventor Ryuichi Inamiya 2274 Hongo, Fuji Xerox Co., Ltd., Ebina City, Kanagawa Prefecture (72) Inventor Hideaki Sekiguchi 2274 Hongo, Ego City, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72) Inventor Sano Haruhiko 2274 Hongo, Ebina-shi, Kanagawa Prefecture F-Xerox Co., Ltd. F-term (reference) 2H033 BA13 BA16 BA20 3F053 AA19 LA02 LA07 LB03

Claims (4)

[Claims] 1. A peeling device for peeling an image support on which a toner image has been fixed from a pair of fixing members, at least one of which is formed of a roll, comprising: A peeling apparatus comprising: a peeling member for peeling an image support from a member; and a charging unit for charging the peeling member to the same polarity as the charging polarity of the image support. 2. A fixing device for fixing a toner image on an image support, wherein at least one of the fixing members is formed by a pair of fixing members made of a roll and conveyed, the fixing device comprising: A fixing device comprising: a separating member for separating the image support from a fixing member comprising a roll; and a charging unit for charging the separating member to the same polarity as the charging polarity of the image support. 3. The fixing device according to claim 2, wherein the charging unit also serves as a unit for charging a fixing member formed of a roll. 4. The fixing device according to claim 2, wherein the peeling member is grounded via a rectifying element.