JPH0652455B2 - 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 and conveys a transfer material and transfers the material to the transfer material by a 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, US Pat. No. 2,567,882
In the publication, a conductive belt and a dielectric member are laminated to each other to form a two-layer structure to form a conveyor belt, and the transfer material is supplied between the conveyor belt and the charging member. 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. 71 is a dielectric belt which is supported and extended by rollers 72 and 73. 7
A metal belt 4 is supported by rollers 76 and 77. A metal foil 75 is opposed to the metal belt 74 with the dielectric belt 71 interposed therebetween. The transfer material 78 is charged by the bias applied between the metal belt 74 and the metal foil 75. 79 is for short-circuiting the metal foil 75 and the transfer material 78. Reference numeral 710 is a guide plate that guides the transfer material 78 to the belt 71.

In U.S. Pat. No. 3,357,325, a corona discharger is used for attracting and transferring a transfer material, and a dielectric single layer belt is used. FIG. 8 shows a schematic view of the embodiment. 81
Is a drum-shaped image support, 82 is a dielectric single layer belt, 8
Reference numerals 3 and 84 are rollers for supporting, stretching and rotating the dielectric belt 82. A roller 85 guides the transfer material 86. Reference numeral 87 is a corona discharger for attracting the transfer material 86 to the dielectric belt 82 by electrostatic force, and 88.
Is a corona discharger for transferring the charged powder image from the image support 81 to the transfer material 86.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in U.S. Pat. No. 3,357,325, the belt is a single dielectric layer, but the corona discharger is for charging the transfer material and adsorbing it onto the dielectric belt. In the case of electrostatically transferring, it is necessary to provide a plurality of independent corona dischargers for transfer only at the transfer position. Further, in the US Pat. No. 2,576,882, it is possible to collectively transfer and convey the charging devices, but from the configuration thereof, like the former US Pat. No. 3,357,325, If the conveyor belt and transfer material are charged enough to obtain a sufficient conveying force, electrostatically transferred charged particles on the transfer material are disturbed when the transfer material and the conveyor belt are separated, resulting in a transfer image. Very likely to have a negative impact on. 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.
For this purpose, it is necessary to use a separate discharger connected to a special power source for static elimination.
No. 244,083 and the like. 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, in U.S. Pat. No. 2,576,882, if the transfer material is curled, the carrying property becomes uneasy. Further, in the above configuration, no consideration has been given to the fact that the transfer force is reduced and the transfer efficiency is reduced due to the decrease in the electric resistance of the transfer material.
In view of the above problems, the present invention realizes a strong transfer property of a transfer material without using a special means at the charging position and effectively using the charged electric charge of the transfer belt regardless of the decrease in the electric resistance of the transfer material. However, it is another object of the present invention to provide a transfer / conveyance device that obtains a high-quality transfer image without performing a complicated static elimination operation.

Means for Solving the Problems In order to solve the above problems, according to the present invention, a transfer belt comprising a transfer material comprising two layers of a dielectric portion charged with a transfer material and a conductor connected to ground or any bias power source, The surface provided in contact with the position prior to the position passes between the conductive members coated with the dielectric, and the surface of the coated dielectric is structured to include a charge removing operation.

Effect of the Invention With the above configuration, the present invention first transfers a part of the electric charge accumulated on the surface of the belt dielectric material to the transfer material during charging of the transfer material conveying belt, and induces it in the belt dielectric in the ground or bias state. The electrostatic attraction between the strong transfer material and the conveyor belt is realized by attracting the electric charge of the opposite polarity to the dielectric part that is being formed, and the transfer material can be stably conveyed without deviation during transfer. is there. At this time, even if the electric resistance of the transfer material is reduced, the transfer material can always have a certain level or more of electric charge by the dielectric material coated on the surface of the conductive member, and a stable carrying force can be realized in any environment. Further, in the transfer method of electrostatically transferring the image by the charged particles, the charge transferred to the transfer material strongly attracts the charged particles, and the image disturbance can be prevented 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 the charger 1.
2 is uniformly charged, 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 in the subsequent developing section 14 by electrostatic force between fine charged particles (hereinafter referred to as toner). The toner image thus obtained on the drum 11 is transferred at the transfer position 15,
The remaining toner on the drum 11 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 cleaned by the cleaning unit 16.
After being wiped off with a blade or the like at
Then, the drum 11 is radiated with uniform charge-eliminating light to remove the charge, and the drum 11 is prepared 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 is composed of two layers, a dielectric layer 112 on the outer side and a dielectric layer 113 on the inner side. In this embodiment, the thickness is 9
A double-layered sheet in which aluminum was vapor-deposited on one side of a 0 μm polyester film was cut into a predetermined size, and the ends were ultrasonically welded. Of course, the outer side may be made of a dielectric material such as nylon or Teflon, and its thickness is preferably 10 μm to 200 μm. The material of the inner layer is not limited as long as it is a conductor, and its thickness is arbitrarily determined from the mechanical strength of the belt including the dielectric layer. Further, even if a belt is formed as a single sheet by laminating dielectric and conductor sheets, or a seamless endless conductor belt is coated with a dielectric layer, formed by laminating, dipping or the like. There is no problem in practice.

The belt 111 is supported by rollers 114 and 115, and is stretched by means such as a spring (not shown) using tension. The surface of the roller 115 is formed of a conductor, and the conductor layer 113 inside the belt 111 is the roller 115.
Is grounded through. This may be appropriately biased depending on the situation. The belt 111 is rotated by driving the roller 115 by a rotation unit (not shown) so that the operation direction of the transfer unit 15 is the same as that of the drum 11 and the peripheral speeds are matched. The surface of the dielectric portion 112 on the outer side of the conveyor belt is charged to the opposite polarity to the toner by the charging corotron 116. This is because, for example, if the toner is negatively charged, the dielectric portion of the belt 111 is positively charged, and the toner on the surface of the drum 111 is electrostatically transferred to the belt 111 side by the electric field based on this positive charge. is there.

Here, the paper 117 is fed between the roller 114 and the roller 118 whose surface is covered with a dielectric and whose conductive member is grounded in time with the drum 11. In this embodiment, the roller 118 is a metal roller.
A 0 μm polyester sheet is wound around the belt 111 by means of a means (not shown) to pinch the roller 11
4 is pressed strongly. Reference numeral 122 denotes a conductive static elimination brush, which is installed at a position apart from the contact position between the roller 118 and the belt 111.

The belt 117 charged when the paper 117 is brought into close contact with the belt 111 by passing between the roller 118 and the belt 111.
Electric charges flow into the paper 117 from the surface of the first dielectric part 112. At this time, how much the paper is charged depends on whether the belt 111, the paper 117, and the roller 118, or the belt 111 and the paper 1.
It is determined by the capacitance and resistance of the air gap layer at the interface between 17 and the roller 118, the value of the capacitance of the roller 118 itself, the nip width when the roller 118 is pressed against the belt 111, and the peripheral speed of the belt 111. FIG. 2 is an equivalent circuit. When the SW is ON, the paper 117 is the belt 111 and the roller 1.
Corresponding to when passing between 18.

It is known that the electrical resistance and electrostatic capacity of paper greatly fluctuate depending on the external environment.Especially at high humidity, the electrical resistance of paper remarkably decreases, and it becomes difficult to retain electric charges and stable conveyance is possible. I can not expect it. If the electric charge of the belt 111 is brought into direct contact with the surface of the conductive member, the belt 1
A large amount of electric charge leaks in 11 and adversely affects the efficiency of electrostatic transfer. In FIG. 2, Q (b) is the roller 1
The amount of electric charge per unit area held by the belt 111 before reaching 18, Cb, Cp, Ca, and Cr are electrostatic capacities of the belt 111, paper 117, air gap layer, and roller 118 per unit area, respectively. Rp and Ra represent the volume resistance of the paper 117 and the air gap layer per unit area, respectively.

If the paper resistance becomes too low, all charge on the belt will be lost, and both transport and electrostatic transfer efficiency will be lost. The charge distribution at this time is shown in FIG. Considering roller 118 as a grounded conductor roller with capacitance Cext connected, no matter how small Rp is, the charge on the belt is eventually divided by Cb and Cext. Will remain. Therefore, Cext is C
If it is too small as compared with b, the electric charge of the belt 111 hardly moves to the paper 117 and the roller 118. Therefore, the dielectric covering the conductive member is preferably 300 μm or less. Further, because of the function of the above-mentioned coated dielectric, the shape is not limited to the roller, and for example, a blade-shaped conductive member may be coated with the dielectric. FIG. 4 shows the distribution of charges on the paper 117 and the belt 111 under high humidity by the roller 118 coated with a dielectric. The capacitance of the dielectric must take into consideration various variables of the equivalent circuit shown in FIG. 2, but the amount of charge on the paper 117 may be set to approximately 10 μC / m ² or more. By doing so, it is possible to realize a stable conveying force above a certain level regardless of the reduction in the electrical resistance of the paper 117.

However, if the surface of the dielectric of the roller 118 is not neutralized, the disappearance of the charge from the surface of the dielectric will naturally decrease according to the number determined by the resistance value and the capacitance of the dielectric of the roller 118 itself, and When the body is made thick, or when a dielectric having a large volume resistivity is coated, such spontaneous charge dissipation may be extremely slow. In this case, electric charge is accumulated by the repeated contact with the paper 117 and the belt 111. An equivalent circuit in this case is shown in FIG. As you can see, roller 1
The charge is accumulated on the dielectric surface of the roller 18 so that the roller 118
The surface potential of the sheet rises and the flow of charges into the paper 117 is prevented. FIG. 6 shows the distribution of charges on the paper 117, the belt 111, and the roller 118 at this time. By destaticizing the dielectric surface of the roller 118,
The electric charge of the belt 111 is always shown in FIG.
You can move to 7.

When the electric resistance of the paper 117 rises due to low humidity, the electrostatic charges of the belt dielectric 112, the paper 117, and the roller 118 are simply divided.

At this time, the electrostatic attraction between the belt dielectric 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. From this, the more the electric charge leaked from the paper 117 by the roller 118, the weaker the adsorption force becomes. This is because the electric field strength E applied to the belt dielectric portion 113 becomes smaller as the charge on the belt disappears.

In this way, the paper 117 strongly attracted to the belt 111 falls off and reaches the transfer position 15 without worrying about slippage, and reaches the belt 1.
A toner image is electrostatically transferred onto the paper 117 from the surface of the drum 11, which is opposed to the toner 11 and the paper 117, by an electric field generated by electric charges having a polarity opposite to that of the toner. Since a certain amount of electric charge remains on the belt, stable transfer is always performed even in high humidity.

After the transfer, the paper 117 and the belt 111 are separated by the suction force of the belt 117 and the rigidity of the paper 117 itself without any special device being required, and the transfer is completed while the paper 117 is in close contact with the belt 111.

After that, the belt 111 and the paper 117 are separated by the curvature of the roller 115 and the rigidity of the paper 117 themselves, transferred to the fixing guide 119, passed through the fixing device 120, and conveyed to a discharge tray (not shown) to complete copying. To do. US Patent 3,
No. 717,801, the electric charge on the charged dielectric belt and the electric charge on the toner on the paper 117 are attracted to each other, and the paper 117
When the belt 111 is separated from the belt 111, the problem that the image is disturbed in which the toner scatters backward with respect to the traveling direction is taken up. As a countermeasure, in U.S. Pat. No. 3,317,801, a special operation is performed 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, the roller 11 by repeatedly passing the paper
It is possible to avoid obstruction of the transfer of charges to the transfer material due to the accumulation of charges on the dielectric surface at 8. For this reason, 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 requiring a special charge eliminating device. Further, in FIG. 1, reference numeral 121 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. When cleaning the toner attached to the belt 111, it was experimentally confirmed that the lower the charge amount of the belt 111 is, the more efficiently the bias applied to the fur brush can be performed at a low voltage. It was found that the roller 118 in the configuration of FIG. 1 divides the electric charge of the belt 111 into the paper 117 and the roller 118, and reduces the charge amount of the belt 111 itself, so that the cleaning property is also significantly effective.

In FIG. 1, a metal roller wound with a dielectric sheet is used. However, for example, an aluminum roller may be anodized to form a dielectric layer on the surface. Alternatively, the dielectric layer may be formed of a shrinkable resin tube. Furthermore, the inside of the roller 118 is not limited to metal,
For example, a rubber material having conductivity may be used.

In the embodiment shown in FIG. 1, the paper 117 is configured to pass above the drum 11, but it may be configured to pass laterally or below the drum 11.

Further, in the present embodiment, the electrophotographic copying apparatus is taken as an example, but the carrying method according to the present invention is also applicable as a transfer / carrying 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. , A transfer material is fed between a conductive member whose surface is coated with a dielectric material, and the transfer material is provided with a means for destaticizing the surface of the dielectric material. Under certain circumstances, transfer a certain level of electric charge from any area, strongly adsorb the transfer material, and perform stable transfer and reliable transfer without misalignment, without any special static eliminator, and without image disturbance Good It is possible to separate the belt and the transfer material and efficiently clean the toner attached to the belt.

[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 FIG. 2 is an equivalent circuit diagram for explaining transfer of charges from a charged transfer / conveyance belt according to the present embodiment to a transfer material. FIG. 3 is a schematic diagram showing a state where the resistance of the transfer material is low and most of the charges are lost from the transfer / conveying belt and the transfer material when the roller 118 is directly grounded, and FIG. 4 is according to this embodiment. 3 is a schematic diagram showing the charge distribution when a transfer material having the same resistance as that in FIG. 3 is transported by the transfer / transport device, and FIG. 5 is FIG. 4 which illustrates the inconvenience caused by not eliminating the dielectric surface of the roller 118. FIG. 6 is a schematic diagram showing the distribution of charges on the transfer / transport belt and the transfer material when charges are accumulated on the dielectric surface of the roller 118, and FIG. 7 is a known method utilizing electrostatic force. Fig. 8 is a schematic view of the transfer material transfer device of Fig. It is a schematic view of the transport device of the known transfer material to use. 11 ... Drum, 12 ... Charger, 13 ... Exposure unit, 1
4 ... Developing unit, 15 ... Transfer unit, 16 ... Cleaning unit, 17 ... Electrification unit, 111 ... Transfer, conveyor belt, 1
12 ... Belt dielectric layer, 113 ... Belt conductor layer,
114 ... driven roller, 115 ... drive roller, 1
16 ... Charger, 117 ... Transfer material, 118 ... Roller, 119 ... Fixing guide, 120 ... Fixing device, 121
…… Conductive fur brush for cleaning 122 …… Conductive brush for static elimination.

Claims (3)

[Claims] 1. A sheet-like or continuous transfer material in the traveling direction is electrostatically supported by using an endless transfer material transport belt,
In an apparatus that conveys and physically or chemically transfers an image to the transfer material, the transfer material transport belt has a surface in contact with the transfer material made of a dielectric and a back surface made of a conductor. Means for supporting and extending and rotating at a constant speed in a certain direction, means for charging the dielectric portion of the transfer material transport belt, and means for grounding or applying an arbitrary bias to the conductor portion of the transfer material transport belt. A means for supplying a transfer material between the charged transfer material conveying belt and a conductive member having a surface coated with a dielectric material, which is arranged prior to the transfer position so as to come into contact with the transfer material conveying belt. A transfer / conveyance apparatus, comprising: a means for destaticizing the dielectric surface coated with the conductive member. 2. The transfer / conveyance apparatus according to claim 1, wherein the conductive member coated with a dielectric is grounded. 3. The transfer / conveyance according to claim (2), wherein the dielectric material covering the conductive member has a relative permittivity of 2 or more and a thickness of 300 μm or less. apparatus.