JPH0731458B2 - Transfer / transport device - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transfer / conveyance device that electrostatically supports / conveys a transfer material and transfers the transfer material onto the transfer material by physical or chemical means.

2. Description of the Related Art Some examples of means for electrostatically transporting a transfer material by forming a belt with an insulating member such as a dielectric are already known. For example, in U.S. Pat.No. 2,567,882, a conductive belt and a dielectric member are laminated to form a two-layered structure to form a conveyor belt, and a transfer material is supplied between the conveyor belt and a charging member. It For this reason, it can be considered as a method in which the paper is not charged by the precharged belt but is sucked by the belt. This embodiment is shown in FIG. 41 is a dielectric belt which is supported and stretched by rollers 42 and 43. A metal belt 44 is supported by rollers 46 and 47. A metal foil 45 is opposed to the metal belt 44 with the dielectric belt 41 interposed therebetween. The transfer material 48 is charged by the bias applied between the metal belt 44 and the metal foil 45. 49 is for short-circuiting the metal foil 45 and the transfer material 48. 410 is transfer material 4
A guide plate for guiding 8 to the belt 41.

In U.S. Pat. No. 3,357,325, a corona discharger is used for adsorption and transfer of a transfer material, and a dielectric single layer belt is used. FIG. 5 shows a schematic view of the embodiment. Reference numeral 51 is a drum-shaped image support, 52 is a dielectric single-layer belt, and 53 and 54 are rollers for supporting, stretching and rotating the dielectric belt 52. 55 is a roller for guiding the transfer material 56. 57 is a corona discharger for attracting the transfer material 56 to the dielectric belt 52 by electrostatic force, and 58 is an image support 51.
A corona discharger for transferring the charged powder image from the transfer material 56 to the transfer material 56.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the one described in U.S. Pat.No. 3,357,325, the belt is a single dielectric layer, but the corona discharger charges the transfer material and adsorbs it onto the dielectric belt. In the case of performing electrostatic transfer, it is necessary to provide a plurality of independent corona dischargers dedicated to transfer at the transfer position. Further, in the one described in U.S. Pat.No. 2,576,882, it is possible to transfer and convey the charging devices as a unit, but it is described in the former U.S. Pat.No. 3,357,325 due to its constitution. Similar to the above, if the transfer belt and transfer material are charged enough to obtain a sufficient transfer force, the insulating property is electrostatically transferred onto the transfer material when the transfer material and transfer belt are separated. It is extremely likely that the charged particles in the image are disturbed and adversely affect the transferred image. For this reason, in the conventional transfer device using the transfer / conveyance belt, it is indispensable to remove the electric charges existing on the belt and the transfer material at the separation position between the transfer material and the conveyance belt. However, it is very difficult to completely remove all the electric charges existing on the transport belt and the transfer material without excess or deficiency, and therefore, use another discharger connected to a special power source for static elimination. What must be done is shown in U.S. Pat. No. 3,244,083. Further, US Pat. No. 3,717,801 discloses that a special discharging device and a power source are used as a method of charging the conveyor belt and the transfer material, but it is hard to say that it is a preferable means in view of economic reasons. Further U.S. Patent No. 2,
In the case of the one described in the specification of 576,882, when the transfer material is curled, the transportability becomes uneasy. In view of the above problems, the present invention realizes a strong transfer property of a transfer material by effectively using the charged electric charge of the transfer belt without using any special means in a charging device, and can achieve a high quality without a complicated static elimination operation. It is to provide a transfer / conveyance device that obtains a transfer image of.

Means for Solving the Problems In order to solve the above problems, according to the present invention, a transfer belt charged with a transfer material and a conductive member provided in contact with the transfer belt prior to the transfer position are connected to an AC power source. It is configured to pass between.

The present invention has the above-described structure, and first transfers a part of the charge accumulated on the surface of the dielectric material to the transfer material at the time of charging the transfer material transport belt, and connects this to ground or an appropriate bias means at the time of charging. By attracting an electric charge of opposite polarity to the dielectric part induced in the belt conductor,
The electrostatic transfer between the strong transfer material and the conveyor belt is realized, and the transfer material can be stably conveyed without any deviation during transfer. Further, in the transfer method of electrostatically transferring an image formed by charged particles, the charge transferred to the transfer material strongly attracts the charged particles, and it is possible to prevent image disturbance even when the transfer belt and the transfer material are separated.

Further, since the transfer material is pressed against the belt and brought into close contact with the belt by electrostatic force, curling of the transfer material does not cause a big problem.

Embodiment Hereinafter, a transfer / conveyance apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross section of a transfer / conveyance apparatus according to the first embodiment of the present invention. In FIG. 1, reference numeral 11 denotes a rotatable drum-shaped image holding member (hereinafter, simply referred to as a drum), and a photosensitive dielectric layer such as selenium is provided on a drum-shaped conductor support such as aluminum. It is provided. Usually this conductor support is grounded. First, the drum 11 is uniformly charged by the charger 12, and the light corresponding to the original is imaged on the drum 11 through a means (not shown), such as a lens, at the next exposed portion 13. At this time, the charge of the portion exposed to the light while the drum surface is uniformly charged disappears by neutralizing the charge of the opposite polarity induced in the conductor support on the back surface of the photosensitive layer, A latent image is formed, that is, a charge pattern corresponding to the lightness and darkness of the original. This latent image is visualized by the electrostatic force between fine charged particles (hereinafter referred to as toner) in the subsequent developing section 14. Drum 11 thus obtained
At the transfer position 15, the upper toner image is electrostatically transferred to the transfer material 117 (hereinafter, referred to as paper) that is conveyed in time with the toner image, and the remaining toner on the drum 11 is removed. After being wiped by a means such as a blade in the cleaning unit 16, the static elimination unit 17 irradiates the drum 11 with uniform static elimination light to eliminate the static electricity and prepare for the next process.

Here, the portion A is a transfer / conveyance device for paper or the like according to the present invention. The belt 111 has a dielectric layer 112 on the outer side and a conductive layer 11 on the inner side.
It consists of two layers. In this example, a double-layered sheet in which aluminum was vapor-deposited on one surface of a polyester film having a thickness of 90 μm was cut into a predetermined size and the ends were ultrasonically welded. Of course, the outside is nylon, Teflon, etc.
Any dielectric material will do. The inner layer may be made of any material as long as it is a conductor. Furthermore, even if the belt is formed as a single sheet by laminating the dielectric and conductor sheets, there is no problem in practice.

The belt 111 is supported by rollers 114 and 115 and stretched by a not-shown means such as a spring with tension. The surface of the roller 115 is formed of a conductor, and the conductor layer 113 inside the belt 111 is grounded through the roller 115. This may be applied with an appropriate bias depending on the situation. The belt 111 is a roller 1 by a rotating means (not shown).
By driving 15, the transfer unit 15 is rotated in the same direction as the drum 11 and at the same peripheral speed. The surface of the dielectric portion 112 on the outer side of the conveyor belt is charged by the charging corotron 116 in the opposite polarity to the toner. For example, if the toner is negatively charged, the dielectric part of the belt 111 is positively charged, and the electric field based on this positive charge causes the drum to rotate.
This is because the toner on the surface of 11 is electrostatically transferred to the belt 111 side.

Here the paper 117 is in time with the drum 11 and the roller 1
Conductive rubber roller 118 connected to 14 and AC power supply 127
Sent between and. Conductive rubber roller in this embodiment
118 is 1 between the surface where the volume resistance contacts the transfer material and the grounding position.
It is of the order of 0 ⁶ Ω, and the belt 111 is strongly pressed against the scissors roller 114 by means not shown. Paper 1 for this
Even if 17 is curled, the paper 117 is pressed against the belt 111.

When the paper 117 passes between the conductive rubber roller 118 and the belt 111 and is brought into close contact with the belt 111, electric charges flow into the paper 117 from the surface of the dielectric portion 112 of the charged belt 111. At this time,
How much the paper is charged depends on the capacitance and resistance of the air gap layer at the interface between the belt 111 and the paper 117 and the conductive rubber roller, or the interface between the belt and the paper and the conductive rubber roller, and the conductive rubber roller.
It is determined by the output voltage and frequency of the AC power supply 127 connected to 118, the nip width when the conductive rubber roller 118 is pressed against the belt 111, and the peripheral speed of the belt 111. FIG. 2 shows an equivalent circuit that seems to determine the distribution of electric charges flowing in by the conductive rubber roller 118, and a schematic diagram showing the distribution of electric charges after the paper 117 has passed through the conductive rubber roller 118. FIG. 2A is an equivalent circuit, in which Sw is ON and the paper 117 is passing between the belt 111 and the conductive rubber roller 118. In FIG. 2 (a), Q (b) is the charge amount per unit area held by the belt 111 before reaching the conductive rubber roller 118, and Cb, Cp, Ca, Cr are the belt 111 per unit area, respectively. , Paper 117, air gap layer, conductive rubber roller 118 capacitance, Rp, Ra, Rr is the paper 117 per unit area, the air gap layer, conductive rubber roller 118 volume resistance, V (f) is It shows an AC power supply voltage. When a bias is applied to the conductor layer 113 of the belt 111, the electrostatic capacitance Cb is grounded via the bias power supply.

It is known that the electrical resistance and capacitance of paper greatly fluctuate depending on the external environment.Especially at high humidity, the electrical resistance of paper remarkably decreases, making it difficult to retain electric charges and stable transport can be expected. Disappear. The distribution of charges on the paper 117 and the belt dielectric surface at this time is shown in FIG. 2 (b). Also, under low humidity, the electrical resistance of the paper increases significantly, making it difficult for the inflow of electric charges. Here, when the conductive rubber roller 118 is connected to the AC power supply 125, the inflow of electric charge from the belt 111 to the paper 117 is promoted or suppressed periodically. Therefore, it is possible to inject a substantially constant electric charge into the paper over a wide range from high humidity to low humidity. FIG. 2C shows the charge distribution when the conductive rubber roller 118 is connected to the AC power supply 127.

Further, when the transfer is performed electrostatically, 100 Hz or higher is desirable because there is a risk of uneven transfer when the frequency of the AC voltage is low.

At this time, the electrostatic attraction between the belt conductor portion 113 and the paper 117 is the product of the electric field strength E applied to the belt dielectric portion 113 and the charge amount Qp of the paper 117. Therefore, conductive rubber roller 11
The more the charge Qp transferred to the paper 117 by 8 is, the stronger the attraction force is. Therefore, the conductive rubber roller 118 is for moving the electric charge from the belt 111 to the paper 117, and the same effect can be expected as long as it is a conductive member regardless of the material and shape. Further, if the resistance value of the conductive member becomes too large, the time constant that regulates the movement of charges becomes too large, and the injection of charges into the paper is hindered. The volume resistance is between the position where the conductive material contacts the transfer material and the ground position.
The preferable range is 10 ¹¹ Ω or less.

In this way, the paper 117 strongly attracted to the belt 111 reaches the transfer position 15 without worrying about slipping off and slipping, and the toner distributed on the belt 111 and the paper 117 generates an electric charge having a polarity opposite to that of the toner. The toner image is electrostatically transferred from the paper to the paper 117.

After the transfer, the paper 117 is separated without any special device due to the suction force of the paper 117 and the belt 111 and the rigidity of the paper 117 itself, and the transfer ends while the paper 117 is in close contact with the belt 111.

After that, the belt 111 and the paper 117 are combined with the curvature of the roller 115 and the paper 117.
After being separated by its own rigidity, it is delivered to the fixing guide 119, passes through the fixing device 120, and is conveyed to a discharge tray (not shown) to complete copying.

In US Pat. No. 3,717,801, the charge on the charged dielectric belt and the charge on the toner on the paper 117 are attracted to each other, and the paper 117 and the belt are attracted.
The problem of image disturbance in which toner is scattered backward in the traveling direction at the time of separation of 111 is taken up. As a countermeasure, the method described in U.S. Pat. No. 3,717,801 uses a special operation as a charging method. Also, some methods have been proposed in which the charge of the paper and the dielectric is removed at the position where the paper and the belt are separated. However, by adopting the configuration of the present invention, since the electric charge transferred to the paper itself strongly attracts the toner even after the separation of the belt and the paper, a high-quality transferred image can be obtained without the need for a special charge eliminating device. .

Further, reference numeral 121 in FIG. 1 denotes a belt cleaning device, which electrostatically removes toner by applying a bias having a polarity opposite to that of the toner to a conductive fur brush, for example. When cleaning the toner adhering to the belt 111, it was experimentally confirmed that the lower the charge amount of the belt 111, the more efficiently the bias applied to the fur brush can be applied at a low voltage.
In the configuration shown in FIG. 1, the conductive rubber roller 118 transfers the electric charge of the belt 111 to the paper 117 and reduces the amount of charge on the belt 111 itself.

FIG. 3 is a diagram showing a second embodiment of the present invention. Instead of the conductive rubber roller 118 in FIG.
This is an example using 26. Also in this case, the same effect as that of the configuration shown in FIG. 1 was obtained.

In the embodiment shown in FIGS. 1 and 3, the paper 117 is the drum 1
Although the structure of passing the upper part of 1 is adopted, it is also possible to adopt the structure of passing the side or the lower part of the drum 11 or the like. Further, in FIGS. 1 and 3, the conductor portion of the belt 111 is kept in the grounded state, but an appropriate bias may be applied to this. Further, an arbitrary DC voltage may be superimposed on the AC output and connected to the conductive member.

In this embodiment, the electrophotographic copying apparatus is taken as an example, but the transfer method according to the present invention is also applicable as a transfer / transfer apparatus used in combination with another transfer method, for example, a transfer method for performing thermal transfer. It is possible.

EFFECTS OF THE INVENTION As described above, the present invention is provided so as to be in contact with a belt composed of two layers of a dielectric material charged with paper and a conductor grounded or biased, and prior to the transfer position. , By transferring the transfer material between the conductive material connected to the AC power supply, the charge is transferred from the belt dielectric part to the transfer material, the transfer material is strongly adsorbed, and stable transfer without deviation is ensured. It is possible to perform the transfer and to separate the belt and the transfer material without image disturbance and to efficiently clean the toner adhering to the belt without providing any special charge removing device.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a transfer / conveyance apparatus according to an embodiment of the present invention, and FIGS. 2A to 2C are equivalent circuits for explaining the distribution of charges on a belt and a paper and schematic diagrams of the charge distribution. FIG. 4 is a cross-sectional view of a transfer / transport device according to another embodiment, FIG. 4 is a schematic side view of a transfer material transport device using a known electrostatic force, and FIG. 5 is a transfer / transport device using a known electrostatic force. It is a schematic side view of a conveyance apparatus. 111 …… Conveyor belt, 112 …… Belt dielectric layer, 113 ……
Belt conductor layer, 116 ... Charger, 117 ... Transfer material, 118
…… Conductive rubber roller, 122 …… Conductive brush.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-59-184377 (JP, A) Actual development 60-128359 (JP, U) Actual public 60-6839 (JP, Y2)

Claims (5)

[Claims] 1. A transfer material carrying belt is composed of a dielectric material on the surface in contact with the transfer material and a conductive material on the back surface, and is endless for electrostatically supporting and carrying the transfer material in a sheet form or in a continuous direction. -Shaped transfer material transport belt, means for supporting and extending the transfer material transport belt and rotating at a constant speed in a certain direction, and means for charging a dielectric portion of the transfer material transport belt,
Means for grounding the conductor portion of the transfer material conveying belt or applying an arbitrary bias, and connected to an AC power source arranged prior to the transfer position so as to contact the charged belt and the transfer material conveying belt. A transfer / conveyance device comprising means for supplying the transfer material through the transfer member. 2. The transfer / conveyance apparatus according to claim 1, wherein the conductive member has a volume resistance value of 10 ¹¹ Ω or less between a portion in contact with the transfer material and the ground. 3. The transfer / conveyance apparatus according to claim 2, further comprising means for pressing a conductive member against the transfer material conveyance belt. 4. The transfer / conveyance device according to claim 3, wherein the conductive member has a roller-like shape. 5. The transfer / conveying device according to claim 4, wherein the conductive member is a rubber material.