JP3356231B2 - Transfer transfer device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / transport device in an electrophotographic image forming apparatus.

[0002]

2. Description of the Related Art As a method for cleaning dirt (mainly toner) attached to the surface of a transfer belt formed of an elastic material, a material having a low friction coefficient or a material having good releasability from toner is used for the belt surface. A coating layer is formed, and cleaning is performed by removing dirt such as toner adhered to the coating layer with a cleaning blade or a brush.

[0003]

The problem that arises when molding a transfer belt is how to coat a material having a low friction coefficient, that is, a hard material, on an elastic belt having elongation. A material having a low coefficient of friction has a lower coefficient of friction as it is harder and exhibits its original properties. However, if the material is coated on an elastic belt, the tension of the belt is increased and the belt cannot be extended. If the belt in this state is forcibly stretched, the coating layer on the surface of the belt is cracked, and the toner enters the cracked portion, and cannot be scraped off with a cleaning plate or a brush, resulting in poor cleaning of the transfer belt surface. There's a problem.
Conversely, if a relatively soft material is used for the low-friction coefficient material so that it can follow the elastic low-belt, the belt tension will not be so high and cracks will be suppressed, but the friction coefficient of the belt surface will be high. As a result, there is a problem that the releasability of the toner is not good and the cleaning of the transfer belt is poor.

[0004]

Therefore, according to the present invention, a coating layer having a low friction coefficient is formed on the surface of an elastic belt constituting a transfer belt in a state where the elastic belt is stretched in advance. In the invention described in Item 2, a coating layer having a low coefficient of friction is formed on the surface of the elastic belt in a state where the elastic belt is heated in advance and stretched in a warm state. In the invention according to claim 3, a rubber belt is used for the elastic belt,
According to a fourth aspect of the present invention, there is provided the transfer / transporting apparatus according to the third aspect, further comprising a belt repairing means for applying zinc stearate to the formed fluorine-coated layer. .

[0005]

According to the first aspect of the present invention, since the coating layer having a low coefficient of friction is formed on the stretched elastic belt, the tensile load on the coating layer when the elastic belt is stretched is reduced. According to the invention described in claim 2, the heating is performed in advance,
In addition, since the coating layer having a low coefficient of friction is formed on the elastic belt that has been stretched in the warm state, the tensile load on the coating layer after drying by heat is reduced. According to the fourth aspect of the present invention, the zinc stearate is repaired on the fluorine coating layer formed in a state in which the transfer belt made of a rubber belt is previously stretched to a use state or heated and stretched in a warm state. By applying by means, even if a crack occurs with time in the fluorine coating layer due to the use of the belt, zinc stearate penetrates into the crack and fills the crack.

[0006]

Embodiments of the present invention will be described below with reference to the drawings. The transfer / conveying apparatus denoted by reference numeral 1 in FIG. 1 supports the belt unit 2 detachably from the main body 1A. The belt unit 2 includes a transfer belt 6 wound around a pair of rollers 4 and 5 for transferring a developed image from the drum-shaped photoconductor 3 shown in FIG. DC solenoid 8 for contact and separation, contact and separation lever 9, bias roller 1 for applying a transfer bias to transfer belt 6
1 and a contact plate 13 for removing charges from the transfer belt 6. A high-voltage power supply 12 for applying a voltage to the cleaning device 16 and a bias roller 11 having a cleaning blade 16A for scraping off residual toner and transfer paper S attached to the surface of the transfer belt 6 is provided to the main body 1A shown in FIG. Is provided.

As shown in FIGS. 1 and 2, the roller 5 has a gear 5b connected to a drive motor (not shown) and is driven to rotate. The transfer belt 6 can move in the transport direction of the transfer paper S (the direction of the arrow A in FIG. 3) at a position facing the photoconductor 3 following the rotation of the roller 5. As shown in FIG. 5, the transfer belt 6 has a two-layer structure, and the surface layer 6b has an electric resistance of 1 × 10 ⁹ Ω to 1 × 10 ¹² Ω on the surface of the belt and an inner layer 6b.
surface resistivity of a is to ^{1 × 10 7 Ω~5 × 10 8} Ω, and its volume resistivity is ^{5 × 10 8 Ω · cm~5 ×} 10 10 Ω · c
It is set to m.

The rollers 4 and 5 are rotatably supported by a support 7 as shown in FIGS. The support 7 can swing about the support shaft 5 a of the roller 5 located downstream of the transfer position with respect to the photoconductor 3 in the transfer paper transport direction indicated by the arrow A among the rollers 4 and 5. . The support 7 is operated by a DC solenoid 8 driven on the transfer position side of the transfer belt 6 by a signal from a control plate 8A. That is, the DC solenoid 8
, A contact / separation lever 9 is connected, and the contact / separation lever 9 moves the support 7 to move the transfer belt 6 toward and away from the photoconductor 3.

[0009] The control plate 8A is arranged such that the leading end of the transfer paper S conveyed in a state where it is aligned with the leading end position of the image formed on the photoreceptor 3 by the registration roller 10 serving as the paper conveying means is transferred to the photoreceptor 3. When approaching, a drive signal is issued to drive the DC solenoid 8. Accordingly, when the solenoid 8 is driven, the support 7 comes close to the photosensitive drum 3 and the transfer belt 6 comes into contact with the photosensitive drum 3. Body 3
A nip portion B that can be conveyed while being in contact with is formed.

In this embodiment, the above-described rollers 4, 5
Among them, the roller 4 located on the photoconductor 3 side is configured as a driven roller with respect to the roller 5 on the driving side,
A conductive roller such as a metal roller having a relatively large electric capacity is floated to provide a function of preventing discharge due to charge-up. Therefore, the charge on the roller 4 is eliminated through the transfer belt 6 having the above-described electrical characteristics. The surface shape of the roller 4 is shown in FIG.
As shown in FIG. 3, both ends 4a, 4a in the axial direction are formed in a tapered shape to prevent the transfer belt 6 from shifting.

The roller 5 on the driving side is formed of an insulating roller for preventing abrupt movement of electric charges which causes peeling discharge when the transfer paper S is separated from the transfer belt 6, which will be described later. Insulating EP rubber or chloroprene rubber is selected as a material in order to also have a function of increasing a grip force on the transfer belt 6 at the time of driving.

The bias roller 11 is provided downstream of the roller 4 in the moving direction of the transfer belt 6 (left side in FIGS. 3 and 4) so as to contact the inside of the transfer belt 6. The bias roller 11 constitutes a contact electrode for applying a charge having a polarity opposite to the charge polarity of the toner on the photoconductor 3 to the transfer belt 6.
It is connected to the.

The contact plate 13 is on the downstream side of the bias roller 11 in the moving direction of the transfer belt 6 (left side in FIGS. 3 and 4), and corresponds to the transfer paper transport surface of the extended portion of the transfer belt 6. On the paper passing surface side, it is arranged at a position facing the transfer paper S with the transfer belt 6 interposed therebetween. The contact plate 13 is for detecting a current flowing on the transfer belt 6 as a feedback current, and a current supplied from the bias roller 11 is controlled by detecting the current.
For this reason, the transfer control plate 1 for setting the supply current to the bias roller 11 according to the detection current is provided on the contact plate 13.
The transfer control plate 14 is connected to the high-voltage power supply 12.

In such a transfer / transport apparatus 1, as shown in FIG. 4, the support 7 moves the transfer belt 6 closer to the photoconductor 3 as the transfer paper S is fed out from the registration roller 10. A nip portion B having a width of about 4 to 8 mm corresponding to the length along the transfer paper conveyance direction is formed between the photoconductor 3 and the photoconductor 3.

On the other hand, the surface of the photoconductor 3 is, for example,-
The toner is charged to 800 V, and as shown in FIG. 6, the toner moves to the nip portion while positively charged toner is electrostatically attracted to the surface. The photoreceptor 3 is arranged near the photoreceptor 3 before reaching the nip portion, and its surface potential is reduced by a pre-transfer neutralization lamp (PTL) 15 that weakens the charge on the surface of the photoreceptor 3. In FIG. 6, the height of the charged charges is represented by the size of a circle, and the pre-transfer static elimination lamp 15
The state in which the amount of the charged electric charge has decreased is shown smaller than the circle indicating before the charge elimination.

In the nip portion B shown in FIG.
The upper toner is transferred onto the transfer paper S by the transfer bias from the bias roller 11 located on the transfer belt 6 side. In this case, the transfer bias from the high voltage power supply 12 to the bias roller 11 is set at -1.5 KV to -2.0 KV, and the potential of the transfer belt 6 at the nip B based on this is -1.3 KV to -2.0 KV. It is set to 1.8 KV.

The potential at the nip portion B of the transfer belt 6 is set for the following reason. That is,
3 and 4, the current value output from the high-voltage power supply 12 is I _1, and the value when a feedback current value flowing from the contact plate 13 to the ground via the transfer belt 6 is I ₂ , I ₁ between these two over I ₂ = I _OUT (However, I _OUT: constant) controlling the value of I ₁ so that the relation is obtained for ... (1). this is,
Temperature, regardless of variations occurring in the production quality of changes in the environmental conditions and the transfer belt 6 such as humidity, is done to eliminate the change in the transfer efficiency by stabilizing the surface potential V _P on the transfer sheet S .

[0018] That is, by Mitateru the current flowing to the photosensitive member 3 side through the transfer belt 6 and the transfer sheet S as I _{OU T,} the transfer belt due to low resistance or high resistance of the surface resistance V _P on the transfer sheet S 6 is prevented from affecting the separation performance and transfer performance of the transfer paper S.

[0019] Thus, the potential of the transfer belt 6 at the nip portion B described above in the present embodiment is set to obtain a surface potential V _P of the transfer paper based on the above reasons, I _OUT in this case In the case of this embodiment, I _OUT = 35 μA ±
When set to 5 μA, good transfer was obtained. In addition,
Surface potential V _P on the transfer sheet S, the environment, by the paper type or the resistance change of the transfer belt 6, a transfer belt 6 described above relates to the potential "-1.3KV~-1.8KV" this range Sometimes it comes off.

When the image is transferred from the photosensitive member 3, the transfer paper S is also charged at the same time. Therefore, the transfer paper S is electrostatically attracted onto the transfer belt 6 and the transfer paper is separated from the photoconductor 3 by the relationship between the true charge on the transfer belt 6 and the polarization charge generated on the transfer paper S side. I can do it. This depends on the height of the transfer bias (−1.3 KV or more) with respect to the charging potential (−800 V) of the photoconductor 3 and, apart from such an electrostatic relationship, the curvature of the photoconductor 3 The transfer paper S is promoted by the peeling operation by the strength of the stiffness of the transfer paper S using the separation.

However, such electrostatic attraction due to such a potential difference causes a current to flow easily through the photosensitive member 3 at high humidity due to a change in environmental conditions, so that transfer paper cannot be separated properly. For this reason, since the resistance value of the surface layer 6b of the transfer belt 6 shown in FIG. 5 is set slightly higher, the transfer of the true charge to the transfer paper S in the nip portion B is delayed so that the photoconductor 3 And the bias roller 11 is positioned downstream of the nip portion B in the transfer paper transport direction. This delays the transfer of the true charges from the transfer belt 6 to the transfer paper S, delays the flow of current to the photoconductor 3, and causes the electrostatic attraction relationship between the transfer paper S and the photoconductor 3 to move. Is to be avoided.

To delay the transfer of the true charge used in this case means that no charge is generated on the transfer sheet S on the upstream side until the transfer sheet S reaches the nip portion on the photosensitive member 6 side. This prevents the transfer paper S from being wound around the photoconductor 3 and also prevents the transfer paper S from separating from the photoconductor 3 from being poorly separated.

Further, it is better to select a transfer belt 6 having a small resistance change due to environmental change. For example, when a rubber belt is used as the elastic belt,
It is desired to select a material having a low hygroscopic property and a stable resistance value, such as chloroprene rubber (CR rubber), instead of a material having a high hygroscopic property such as urethane rubber.

The current I _OUT flowing to the photosensitive member 3 side
Is not unambiguous, and can be reduced when the potential of the toner used is low, as in a digital system, and conversely, when the pre-transfer neutralization lamp 15 is not used, It increases as the surface potential of the body 3 increases.

On the other hand, the transfer paper S that has passed through the nip B is
The transfer belt 6 is conveyed in accordance with the movement of the transfer belt 6, and the electrostatic attraction relationship between the transfer belt 6 and the transfer belt 6 is relaxed or released by the charge removing action of the contact plate 13. The speed at which is reduced depends on these factors when the resistance value of the transfer paper S is R and the capacitance is C, and the time constant (τ) = C · R (2) Required by

Therefore, since the time required for the charge amount to be reduced easily in the OHP sheet or the transfer paper S having a high resistance at low humidity, the separation of the curvature by the roller 5 on the driving side is likely to occur. Done. Therefore, the diameter of the roller 5 is 1
It is set to 6 mm or less. Further, when such a roller 5 is used, high-quality 45K paper (rigidity 21 [cm
^3/100]) experimental result that separation is possible of is obtained.

When the transfer of the image onto the transfer sheet S and the separation of the transfer belt 6 are completed, the contact / separation lever 9 is released in response to the excitation of the DC solenoid 8 being released.
The support 7 is separated from the photoconductor 3. Then, the surface is cleaned by the cleaning device 16.

The transfer paper S peeled off from the photoreceptor 3
Is electrostatically attracted to the transfer belt 6 and the fixing unit 17
Is transported between the heating roller 17a and the pad roller 17b. The fixing unit 17 heats and melts the toner on the transfer paper S and presses the toner on the transfer paper S to fix the toner on the transfer paper S.

The cleaning device 16 is provided with a cleaning blade 16A, and the toner transferred from the surface of the photoreceptor 3 or scattered around the transfer belt 6 without being transferred by rubbing the transfer belt 6. Is scraped off the toner and the paper powder of the transfer paper S when the toner adheres.

The transfer belt 6 rubbed by the cleaning blade 16A has a low friction coefficient in order to prevent an increase in driving force due to an increase in rubbing resistance or a phenomenon such as turning up of the cleaning blade 16A. . For this reason, in this embodiment, the surface of the transfer belt 6 is coated with fluorine (polyvinyldene fluoride). The toner or paper dust scraped off from the surface of the transfer belt 6 is collected by the collecting screw 16B into the main body 1.
A is stored in a waste toner collecting container (not shown).

On the other hand, the inner layer 6a of the transfer belt 6 described above
Is made of a rubber belt, and the surface layer 6b is made of a hard fluorocarbon resin having a low coefficient of friction. The surface layer 6b is applied to the surface of the rubber belt stretched to the state of use wound around the rollers 4 and 5 by applying a liquid fluorocarbon resin, or by heating the rubber belt to maintain the heat-retaining state. After being stretched to a state of use wound around the rollers 4 and 5, a fluororesin is applied to the surface thereof, and then dried. That is, after applying the liquid fluororesin, it is baked and dried in a state where it is stretched in advance to an elongation ratio in a use state. The elongation here is 2-3%.

Accordingly, in using the transfer belt made of rubber, even if the belt is wound around the rollers 4 and 5, the surface layer 6b is formed on the inner layer 6a which has been stretched in advance, so that the belt is wound on the surface layer 6b. The tensile load is reduced, and the surface layer 6b
Cracks are prevented.

Next, a transfer / conveyance device having a function of restoring the transfer belt 6 will be described with reference to FIG. FIG.
1 to 6 are denoted by the same reference numerals as those used in the transfer / conveyance device 1 shown in FIGS.
The description is omitted.

The transfer / transportation device 20 shown in FIG. 7 is obtained by adding a restoring means 21 to the transfer / transportation device 1 described above.
The repairing means 21 is an application roller whose surface is impregnated with powdered zinc stearate.
It is rotatably supported further downstream (to the right in FIG. 7), and comes into contact with the surface of the transfer belt 6 when separated from the photoconductor 3.

The zinc stearate is applied to the surface of the transfer belt 6 which has been cleaned as the transfer belt 6 moves, and the belt surface layer 6b formed of a fluororesin is used as the transfer belt 6 is used.
And penetrate into the subtle cracks that occur in the cracks. Thus, the transfer belt 6 after cleaning is
By applying powdered zinc stearate to the surface, cracks that occur over time can be repaired. 7 is a bias terminal made of a conductive member also serving as a stay of the bias roller 11, and a transfer bias from the high voltage power supply 12 is supplied to the bias roller 11 via the bias terminal 22. I have.

In the present embodiment, the restoration means 21 is a roller, but may be an application brush. The application roller serving as the repair unit 21 is configured to apply the zinc stearate in contact with the transfer belt 6 distant from the photoreceptor 3, for example, by fixing the repair unit 21 to the support 7, It is also possible to adopt a configuration in which the transfer belt 6 can be moved together with the contact / separation operation, and is always in contact with the transfer belt 6.

Alternatively, the restoring means 21 may be configured to be able to freely contact and separate from the transfer belt 6 with an actuator such as a solenoid (not shown). At this time, in the case of a copying machine, the actuator is connected to control means according to the control plate 8A or the like shown in FIG. 1 in which the number of copies is set in advance. To drive the application roller and brush to transfer belt 6
, And may be automatically repaired. Further, the actuator is connected to a manual switch provided on an operation unit (not shown) on which a numeric keypad and the like are arranged, and a user of the device looks at the copy image, and when the background dirt is conspicuous, operates the manual switch to operate the actuator. The transfer belt 6 may be repaired.

[0038]

According to the present invention, when forming a coating layer on the surface of a transfer belt composed of an elastic belt made of a hard material having a low coefficient of friction, the elastic belt is previously stretched to the same elongation as when used. Since the material having a low coefficient of friction is coated while being stretched or heated and kept warm, the tensile load on the formed coating layer is reduced, and the elastic belt is prevented from cracking. Accordingly, it is possible to prevent the toner and the like from entering the cracks, thereby providing a transfer / transport device having excellent cleaning performance.

Further, by applying zinc stearate to the formed fluororesin coating layer by a repairing means, it is possible to repair cracks which occur with time in the coating layer due to the use of the transfer belt. This leads to the provision of a transfer conveyance device that can obtain good cleaning performance over a period.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating a schematic configuration of a transfer / conveyance apparatus according to an embodiment of the invention.

FIG. 2 is a plan view illustrating a schematic configuration of a transfer belt unit.

FIG. 3 is a layout diagram illustrating a schematic configuration of a transfer / conveyance device of the present invention.

FIG. 4 is an arrangement diagram showing an operation at the time of transfer of the transfer / conveyance device shown in FIG. 3;

FIG. 5 is a partially enlarged cross-sectional view of a transfer belt used in the transfer conveyance device of the present invention.

FIG. 6 is an enlarged view showing a transfer operation of toner particles.

FIG. 7 is a layout diagram illustrating a schematic configuration of a transfer / conveyance apparatus having a belt repair unit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 20 Transfer conveyance device 3 Photoconductor 6 Transfer belt 6b Coating layer with low friction coefficient 21 Belt repair means S Transfer paper

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tadashi Matsuda 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (72) Yuko Harazawa 1-3-6 Nakamagome, Ota-ku, Tokyo Ricoh Co., Ltd. (72) Inventor Koichi Ishii 1-3-6 Nakamagome, Ota-ku, Tokyo, Ricoh Co., Ltd. (56) References JP-A-4-29276 (JP, A)

Claims (4)

(57) [Claims] 1. The method according to claim 1, wherein the image information on the photoreceptor is transferred onto a transfer paper.
And a transfer layer using an elastic belt as a transfer belt for electrostatically adsorbing and transferring the transfer paper, wherein a coating layer having a low friction coefficient is formed on the surface of the elastic belt in a state of being stretched in advance. A transfer conveyance device characterized by the above-mentioned. 2. The method according to claim 1, wherein the image information on the photoreceptor is transferred onto a transfer paper.
And, in the transfer conveying device using an elastic belt to a transfer belt for attracting transport the same transfer paper electrostatically, pre-warmed, and <br/> the elastic belt in a state of being stretched in the heat retaining state A transfer layer, wherein a coating layer having a low coefficient of friction is formed on the surface of the sheet. 3. The transfer / transport apparatus according to claim 1, wherein a rubber belt is used as the elastic belt, and a fluorine coating layer is formed on the surface of the belt. 4. A rubber belt is used as an elastic belt, a fluorine coating layer is formed on the surface of the belt, and belt repair means for applying zinc stearate to the fluorine coating layer is provided. 3. The transfer conveying device according to 1 or 2.