JP2001072281A - Transfer conveying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stably convey a transfer material to a fixing means and to prevent the formation of an abnormal image caused by discharging, by mounting a discharging member on the way in the guiding direction of a guide member capable of guiding the transfer material as an image holding member having a transferred toner image and guiding the transfer material separated from a transfer belt. SOLUTION: When the transfer paper separated from a transfer belt is conveyed on a guide member 18 having a discharging member 36, the attraction force caused by the electrostatic induction is produced between the transfer paper and the guide member 18 made of a material of intermediate resistance, because the transfer paper is charged, and the transfer paper is conveyed on a rib 34 along the guide member 18. Then the transfer paper is discharged by the discharging member 36, here, the sudden electrolytic fluctuation can be prevented by executing the discharging over a wide range with a predetermined distance t1 with respect to a discharging needle 36b, and the flying of the toner can be also prevented. As the transfer paper is conveyed on the rib 34, the transfer paper can be prevented from being soiled even though a main body of the guide member 18 is soiled by the toner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / conveyance apparatus provided in an image forming apparatus such as a copying machine, a printer, a facsimile, etc., and more particularly, to a transfer / conveyance apparatus using a dielectric transfer belt.

[0002]

2. Description of the Related Art In a transfer transfer apparatus of this type, a charge is applied to an endless dielectric transfer belt by a charge applying means, and the transfer belt is rotated by a belt driving means on an image carrier. Is transferred onto a transfer material (transfer paper) on a transfer belt. Further, the transfer paper on which the toner image has been transferred is electrostatically attracted onto the transfer belt and conveyed, and the transfer paper separated from the transfer belt is guided by a guide member to the fixing unit. In a transfer conveyance device using a transfer belt, when a transfer paper on which a toner image has been transferred is separated from the transfer belt, a peeling discharge occurs due to a sudden increase in potential due to a change in a gap between the charged transfer paper and the transfer belt, There is a problem that the toner image in the unfixed state is disturbed and the toner scatters, resulting in an abnormal image. Also,
Similarly, when the transfer paper is conveyed on the guide member or when the transfer member is separated from the guide member, a discharge phenomenon occurs, and the guide member becomes soiled with toner, and the stain adheres to the back surface or the end surface of the next transfer paper. There is a problem.

In Japanese Patent Application Laid-Open No. Hei 6-317990, in a configuration for absorbing slack of a transfer sheet due to a difference in linear speed between a fixing unit and a transfer belt, a guide surface of a guide member is formed of a conductive material, There is disclosed a technology for providing a static elimination brush on the exit side to effectively eliminate static. In Japanese Patent Application Laid-Open No. Hei 6-180538, a change in the volume resistivity of the transfer belt and the volume resistivity of the guide member is reduced to suppress electric field fluctuation, and a plurality of ribs extending in the guide direction are provided on the transfer paper guide surface of the guide member. A technique has been proposed in which the transfer sheet is formed so that the transfer sheet does not directly contact the soiled portion even if the guide member is soiled with toner.

[0004]

Problems to be Solved by the Invention Japanese Patent Laid-Open No. 6-31799
In the configuration described in Japanese Patent Application Laid-open No. 0, since the transfer paper is excessively neutralized on the exit side of the guide member, the transfer paper is less likely to be electrostatically attracted to the next fixing entrance guide member. For this reason, the leading edge of the transfer paper enters the nip portion of the fixing means, and the rear end of the transfer paper is conveyed by the transfer belt. Tended to bulge, in which case an abnormal image was sometimes caused by the discharge. The configuration described in Japanese Patent Application Laid-Open No. 6-180538 has a problem that the static elimination action is weaker than static elimination by a static elimination brush or the like, and an abnormal image of a rib pitch is generated due to discharge when separated from the guide member.

That is, in this type of transfer / transport apparatus, if the charge is removed too much, the transferability of the transfer paper is impaired. Conversely, if the charge is insufficient, the problem of an abnormal image due to discharge occurs.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a transfer / transport apparatus which can obtain a stable transfer property of a transfer material to a fixing means and can suppress occurrence of an abnormal image due to discharge.

[0007]

According to the first aspect of the present invention, a toner image on an image carrier is transferred to a transfer material, and the transfer material can be electrostatically attracted and conveyed. Transfer belt, a charge applying means for applying an electric charge to the transfer belt, a belt driving means for rotating the transfer belt, and a transfer conveyance device having a guide member for guiding a transfer material separated from the transfer belt, A configuration is adopted in which a static elimination member is provided in the guide direction of the guide member.

According to a second aspect of the present invention, in the configuration of the first aspect, the guide member is made of a medium-resistance material, or is a medium-resistance or conductive material and is in contact with the transfer material. The surface is made of an insulating or medium-resistance material.

According to the third aspect of the present invention, the first or second aspect is provided.
In the configuration described above, a configuration is adopted in which the static elimination member is grounded and provided so as not to contact the transfer material.

According to a fourth aspect of the present invention, in the configuration of the third aspect, the static elimination member has an extended shape on the back surface side of the guide member.

According to the invention described in claim 5, claim 1 or 2
In the configuration described above, the static elimination member is provided on the back surface side of the guide member and connected to a grounded or low-potential conductive member and provided so as not to contact the transfer material. Is adopted.

According to a sixth aspect of the present invention, in the configuration of the fourth aspect, the back surface of the guide member is formed of a medium resistance material, and the charge removing member is in contact with the back surface of the guide member. Has been adopted.

According to a seventh aspect of the present invention, in the configuration of the fifth aspect, the back surface of the guide member is formed of a medium resistance material, and the conductive member is in contact with the back surface of the guide member. It has a configuration.

According to an eighth aspect of the invention, in the configuration of the seventh aspect, the conductive member is formed directly as a conductive layer on the back surface of the guide member.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. As shown in FIG. 1, the transfer transport device 2 in the present embodiment includes a dielectric transfer belt 4, a charge application unit 6 that applies electric charges to the transfer belt 4, and a belt driving unit that rotates the transfer belt 4. A driving roller 8 and a driven roller 10, a cleaning unit 12 for cleaning the surface of the transfer belt 4, a housing 14, and a transfer paper 16 as a transfer material separated from the transfer belt 4 are guided to a fixing unit (not shown). It has a guide member 18 and the like.

The transfer belt 4 is provided so as to contact a photosensitive drum 20 as an image carrier at a transfer position (nip portion). Although not shown, as is well known, the photosensitive drum 20 is uniformly charged by a charging unit, then is exposed to an image by an exposure unit to form an electrostatic latent image, and the electrostatic latent image is formed by a developing unit. It is developed into a toner image. The transfer paper 16 supplied from a paper supply unit (not shown) is imaged (toner image) on the photosensitive drum 20 by a pair of registration rollers 22.
Is transferred to the nip portion between the photosensitive drum 20 and the transfer belt 4 at a timing when the leading end of the transfer belt 4 coincides with a predetermined position in the transport direction.

The transfer belt 4 is constituted by a medium resistance member made of an elastic rubber member. The surface of the transfer belt 4 is made of a fluorine-based material, has a low surface friction coefficient, and can be stably cleaned by the cleaning unit 12. As a fluorine-based material,
Polyvinylidene fluoride, tetrafluoroethylene and the like are coated with a dispersing material to a thickness of about 5 to 15 μm, and have a surface resistivity (JISK691) of 1 × 10E10Ω to 1 ×
10E12Ω. For the material of the inner base layer, a rubber material such as chloroprene rubber, EPDM rubber, epichlorohydrin rubber, or a blend material thereof is used.
If necessary, a conductive material such as carbon or metal oxide is blended to control the resistance value. Surface resistivity of base layer (J
ISK6911) is 1 × 10E7Ω to 5 × 10
E9Ω is appropriate.

The drive roller 8 has a metal core and a rubber material wound around its outer periphery, and is electrically floated. The driven roller 10 is made of a metal member, and the transfer roller 4
It also has a function as a feedback roller that feeds back a current that does not flow to zero. The driving roller 8 includes
Rotational force in the direction of the arrow is transmitted by a drive source (not shown),
Since the outer peripheral surface of the drive roller 8 and the back surface of the transfer belt 4 have a high friction coefficient between the rubber surfaces, the rotational force of the drive roller 8 is transmitted without slipping, and the transfer belt 4 rotates. The driven roller 10 rotates together with the movement of the transfer belt 4.

The charge applying means 6 is disposed so as to be in contact with the back surface of the transfer belt 4 downstream of the nip portion between the transfer belt 4 and the photosensitive drum 20, via the bias terminal 26. And a transfer bias roller 28 connected to a high voltage power supply 24. The transfer bias roller 28 is made of a metal member such as SUS. The charge applying means 6 has a current control unit (not shown). The current control unit applies a transfer bias to the transfer bias roller 28 from the high-voltage power supply 24 and transfers the transfer bias from the high-voltage power supply 24 via the transfer bias roller 28. The current I1 supplied to the belt 4 is compared with the current I2 which does not flow from the transfer belt 4 to the photosensitive drum 20 and is fed back via the driven roller 10, and the difference (I1-I
The output of the high voltage power supply 24 is controlled so that 2) becomes a constant value K. By this output control, the current flowing from the transfer belt 4 to the photosensitive drum 20 is set to a constant value (substantially K), and the toner image is transferred onto the transfer paper 16 under the stable transfer conditions at all times. Note that the current control unit may be configured to also serve as the main control of the image forming apparatus provided with the transfer / conveyance device 2.

The cleaning means 12 has a cleaning blade 30 which comes into contact with the surface of the transfer belt 4 to scrape off residual toner and the like, and a screw-like collecting member 32 which collects residual toner and the like accumulated in the housing portion of the housing 14. are doing.

Next, the guide member 18 will be described in detail with reference to FIGS. The guide member 18 is provided on the transfer paper 16.
Have a plurality of ribs 34 on the guide surface for guiding the. The ribs 34 have a length that extends in the transfer direction (guide direction) of the transfer paper 16, and a plurality of ribs 34 are formed at intervals in a width direction substantially orthogonal to the transfer direction of the transfer paper 16. As the material of the guide member 18, a medium-resistance resin material, for example, antistatic ABS (trade name: Toyolac Parel), polycarbonate and ABS
Resin (trade name: Multilon) or the like is used, and the volume resistivity is 1 × 10E8Ωcm to 1 × 10E.
A medium resistance of 13 Ωcm which is close to the resistance of the transfer belt 4 is selected.

A central portion of the guide member 18 is hollowed out to form a concave portion 35, and a static elimination member 36 is provided in the concave portion 35 in a buried state. The static elimination member 36 is formed of a stainless steel material, and has a base portion 36a extending in the longitudinal direction of the guide member 18 (the width direction of the transfer paper 16), and a large number integrally formed on the base portion 36a so as to rise obliquely upward. Of the static elimination needle 36b. In the present embodiment, the pitch of the static elimination needle 36b is 2 mm. Base part 36
“a” is grounded to the casing of the image forming apparatus (not shown).

As shown in FIG. 2, the distance t1 between the tip of the static elimination needle 36b and the lower surface of the guide member 18 without the rib 34 is set to at least 0.5 mm or more. At the time of guiding the guide 16 (at the time of conveyance), the tip of the static elimination needle 36b does not directly contact the transfer paper 16. It is desirable that the distance t2 between the transfer paper 16 and the tip of the static elimination needle 36b when the transfer paper 16 is transported on the upper surface of the rib 34 is approximately 2 to 4 mm. Guide member 18
3 is fixed to the housing 14 with screws (not shown) via screw insertion holes 18a and 18b formed at both ends, as shown in FIG. FIG. 4 is a diagram viewed from the arrow A side in FIG.

Next, the transfer paper 16 on the guide member 18 is
Will be described. When the transfer paper 16 separated from the transfer belt 4 is conveyed over the guide member 18 having the above-described charge removing member 36, the transfer paper 16 is electrically charged, so that the transfer paper 16 is electrically charged. The transfer paper 16 is attracted to the guide member 18 by electrostatic induction.
Is transported along the ribs 34 along the. Then, the transfer paper 16
Is removed by the charge removing member 36, but the charge is removed over a wide range with the distance (t1) between the charge removing needle 36b and the charge removing needle 36b, so that a sudden electric field fluctuation does not occur, and thus toner does not scatter. Since the guide member 18 is conveyed on the ribs 34, even if the main body of the guide member 18 is contaminated with toner, the contaminant does not adhere to the transfer paper 16.

The static elimination member 36 is grounded, but has a lower static elimination efficiency than a conventional case where a direct current bias having a polarity opposite to that of the transfer bias is applied to the static elimination needle.
Is transported in a state where electric charges still remain. For this reason, an electrostatic attraction force is continuously generated between the remaining charge and the guide member 18, and stable transfer is performed until the transfer paper 16 passes through the guide member 18. Further, due to the charge elimination to some extent, no abrupt electric field fluctuation occurs when the transfer paper 16 is separated from the guide member 18, and an abnormal image due to toner scattering or discharge does not occur.

The configuration in which the neutralizing member 36 is grounded is simpler than the conventional configuration in which a DC bias having a polarity opposite to that of the transfer bias is applied to the neutralizing needle. In addition, in particular, when a positive polarity is used for the transfer bias, there is an advantage that the amount of ozone generated in the transfer and transfer device including the charge elimination can be extremely reduced. In the present embodiment, the guide member 18 is formed of a medium-resistance material. However, even if the guide member 18 is formed by coating an insulating material on a medium-resistance material or having a two-layer structure with an insulating layer, the guide member 18 may be formed by an electrostatic attraction force. A stable transfer of the transfer paper 16 is obtained. A similar function can be obtained by providing a medium resistance material or an insulating material on a conductive material.

FIG. 5 shows a guide member and a charge removing member in another embodiment. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and have the same configuration except for the main part, so that the description is omitted. In the present embodiment, the guide member 38 is
The base portion 36a of the charge removing member 36 is provided on the rear surface side of the guide member 18 so as to correspond to the shape of the concave portion 40.
Has a shape extended in the transport direction. Due to the extended shape of the base portion 36a, the charge removing member 36 is reliably grounded, and the electrostatic attraction force required for stable conveyance of the transfer paper 16 can be increased. The back surface of the guide member 38 may be formed of a medium-resistance material, and the base portion 36a may contact the back surface. Further, the charge removing member 36 may be set to a low potential via a low resistance element or a constant voltage element without grounding the base portion 36a.

FIG. 6 shows a guide member and a charge eliminating member in another embodiment. The same parts as those in the above-described embodiment are denoted by the same reference numerals, and have the same configuration except for the main part, so that the description is omitted. The guide member 44 in this embodiment has a concave portion 46, and aluminum plates 48, 50 as conductive members are provided in contact with the back surfaces 44c, 44d of the guide member 44, which are the inner surfaces of the concave portion 40. I have. The aluminum plates 48 and 50 are electrically connected to the static elimination member 36. Therefore, the aluminum plates 48 and 50 are also connected to the static elimination member 36.
Grounded.

The aluminum plates 48 and 50 serve as the guide members 4
4, because it is in contact with the back surfaces 44c and 44d of the medium resistance,
Electric charges accumulated in the guide member 44 can be released as current. Thereby, the guide member 44 having a medium resistance is charged by the rubbing in the transfer of the transfer paper 16, and the transfer paper 1 is charged by the influence thereof.
6 can prevent an abnormal image that disturbs the unfixed image. Similar effects can be obtained by directly plating or depositing metal such as aluminum or copper on the back surfaces 44c and 44d of the guide member 44 or coating with a conductive paint instead of the metal plates such as the aluminum plates 48 and 50. be able to. In this case, there is an advantage that the adhesion between each conductive layer and the guide member 44 is further improved, and the function of releasing charges is further improved. In addition, since the conductive layer is thin and soft, it can follow the thermal expansion of the guide member 44, and can prevent functional deterioration due to poor contact.

[0030]

According to the first or second aspect of the present invention, since the charge removing member is provided in the middle of the guide member in the guide direction of the transfer material, the transfer material is stably conveyed while being electrostatically attracted to the guide member. In addition to the above, since the transfer material can be neutralized, the occurrence of an abnormal image due to the discharge after the guide member can be suppressed.

According to the third aspect of the present invention, the static elimination member is provided so as not to contact the transfer material and the static elimination member is grounded, so that insufficient static elimination and excessive static elimination can be reliably prevented, and the transfer material can be stabilized. The conveyance and the suppression of abnormal images can be improved.

According to the fourth aspect of the present invention, since the discharging member has a configuration extended on the back side of the guide member, the grounding of the discharging member can be ensured. It is possible to prevent the occurrence of an abnormal image due to insufficient static elimination.

According to the fifth aspect of the present invention, since the discharging member is provided on the back side of the guide member and connected to the grounded or low potential conductive member, the grounding of the discharging member is performed. Can be ensured, and occurrence of an abnormal image due to insufficient static elimination can be prevented.
In addition, since the charge removing member is provided so as not to contact the transfer material, excessive charge removal can be prevented, and stable transfer of the transfer material by electrostatic attraction can be obtained.

According to the sixth aspect of the present invention, since the discharging member is configured to be in contact with the back surface of the medium resistance guide member, the electric charge accumulated in the guide member can be released as a current and the guide member can be released. It is possible to prevent the occurrence of an abnormal image due to the electrification.

According to the seventh aspect of the present invention, since the conductive member connected to the neutralizing member is in contact with the back side of the medium resistance guide member, the electric charge accumulated in the guide member is converted into a current. The guide member can be released, and the occurrence of an abnormal image due to charging of the guide member can be prevented.

According to the eighth aspect of the present invention, since the conductive member is formed as a conductive layer formed directly on the back surface of the guide member, the conductive member can follow a change in thermal expansion of the guide member.
It is possible to prevent the deterioration of the abnormal image suppression function over time due to poor contact.

[Brief description of the drawings]

FIG. 1 is a schematic front view of a transfer conveyance device according to one embodiment of the present invention.

FIG. 2 is a schematic sectional view of a guide member.

FIG. 3 is a schematic plan view of a guide member.

FIG. 4 is a side view of a main part of a guide member.

FIG. 5 is a schematic sectional view of a guide member according to another embodiment.

FIG. 6 is a schematic sectional view of a guide member according to another embodiment.

 ────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Ryo Tagami 1-3-6 Nakamagome, Ota-ku, Tokyo F-term in Ricoh Co., Ltd.

Claims (8)

[Claims] A transfer belt configured to transfer a toner image on an image carrier to a transfer material and electrostatically adsorb and transfer the transfer material; a charge applying unit configured to apply a charge to the transfer belt;
In a transfer conveyance device having a belt driving means for rotating the transfer belt and a guide member for guiding a transfer material separated from the transfer belt, a charge removing member is provided in the guide direction of the guide member. Transfer device. 2. The transfer conveying device according to claim 1, wherein the guide member is made of a medium-resistance material.
Alternatively, a transfer / conveying apparatus characterized in that the transfer material is a medium-resistance or conductive material and a surface in contact with the transfer material is made of an insulating or medium-resistance material. 3. The transfer / conveying device according to claim 1, wherein the charge removing member is grounded and provided so as not to contact the transfer material. 4. The transfer conveyance device according to claim 3, wherein the charge removing member has an extended shape on the back side of the guide member. 5. The transfer / conveying device according to claim 1, wherein the static elimination member is provided on a back side of the guide member and is connected to a grounded or low-potential conductive member. And a transfer conveyance device provided so as not to contact the transfer material. 6. The transfer conveyance device according to claim 4, wherein the back surface of the guide member is formed of a medium resistance material, and the charge removing member is in contact with the back surface of the guide member. apparatus. 7. The transfer device according to claim 5, wherein the back surface of the guide member is formed of a medium resistance material, and the conductive member is in contact with the back surface of the guide member. Transport device. 8. The transfer / transport apparatus according to claim 7, wherein the conductive member is formed as a conductive layer directly on the back surface of the guide member.