JPS62215976A - Transfer and carrying device - Google Patents

Abstract

PURPOSE:To easily realize the strong carrying property of a transfer material, and to form a transfer image having a good quality by applying a bias voltage in accordance with the result of monitoring of an electric resistance of the transfer material, to the rear side electric conductor of a transfer material carrying belt whose surface is a dielectric. CONSTITUTION:The electric resistance of a transfer material 117 which is carried by a carrying belt 111 constituted of a dielectric layer 112, and an electric conductor layer 113 whose surface and rear side are electrified by an electrifier 116, and a conductive roller 118 which is connected to a ground is monitored by a surface potential sensor 122. In accordance with the result of this monitoring, a DC bias voltage applied to the layer 113 through a driving roller 115, and the polarity are controlled by a bias output control device 124. In this way, the electrifying charge of the belt 111 is used effectively and the strong carrying property of the transfer material by an electrostatic attraction is realized easily, an image transfer is executed to the transfer material from a photosensitive drum 11 by carrying which is free from the deviation, and the image having a good quality is formed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to a transfer/conveying device that electrostatically supports and conveys a transfer material and performs transfer onto the transfer material by physical or chemical means.

BACKGROUND OF THE INVENTION Several examples are already known of means for electrostatically conveying a transfer material by constructing a belt from an insulating member such as a dielectric material. For example, U.S. Patent 2,567,882
In the publication, a conductive member and a dielectric member are bonded together to form a two-layer structure to constitute a conveyor belt, and the transfer material is supplied through between the conveyor belt and the charging member. For this reason, it can be seen as a method in which paper is charged and then attracted to the belt, rather than being attracted to a pre-charged belt.

FIG. 5 shows this embodiment. 51 is a dielectric belt supported and stretched by rollers 52 and 53.

54 is a metal belt supported by rollers 56 and 57. A metal foil 55 faces the metal belt 54 with the dielectric belt 51 in between. The transfer material 58 is charged by the bias applied between the metal belt 54 and the metal foil 55. Reference numeral 59 short-circuits the metal foil 55 and the transfer material 58. 510 is a guide plate that guides the transfer material 58 to the belt 51.

In US 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. 6 shows a schematic diagram of the embodiment. 61
62 is a drum-shaped image carrier, 62 is a dielectric single-layer belt, and 63 is a drum-shaped image carrier.
．． 64 is a roller for supporting, stretching, and rotating the dielectric belt 62. 65 is a roller for guiding the transfer material 66. 67 is a corona discharger for adhering the transfer material 66 to the dielectric belt 62 by electrostatic force, and 68 is a corona discharger for transferring the charged powder image from the image support 61 to the transfer material 66.

Problems to be Solved by the Invention However, in U.S. Pat.
In the case of electrostatic transfer, it is necessary to provide a plurality of independent corona dischargers at the transfer position, one for charging the transfer material and adhering it to the dielectric belt, and the other for electrostatic transfer. Further, in U.S. Pat. No. 2,576,882, it is possible to perform transfer and conveyance by combining the charging devices, but due to its structure, similar to the former U.S. Pat. No. 3,357,325, If the conveyor belt and transfer material are charged to the extent that sufficient conveyance force is obtained, when the transfer material and the conveyor belt are separated, the charged particles electrostatically transferred onto the transfer material will be disturbed and the transferred image will be disrupted. Therefore, in transfer devices that use conventional transfer/conveyance belts, it is essential to perform an operation to eliminate the electric charge existing on the belt and transfer material at the separation position between the transfer material and the conveyance belt. Ta. However, it is extremely difficult to completely remove all of the charges existing on the conveyor belt and the transfer material.
For this purpose, it is necessary to use a separate discharger connected to a special power source for static elimination, as disclosed in US Patent 3.2.
This is shown in Publication No. 44.083 and the like. Further, as a method of charging the conveyor belt and the transfer material, the use of a special discharger and a power source is shown in US Pat. Furthermore, in US Pat. No. 2,576,882, if the transfer material is curled, there is concern about conveyance performance. Furthermore, in the above configuration, no consideration was given to the fact that the conveyance force and transfer efficiency are reduced due to a reduction in the electrical resistance of the transfer material. In view of the above-mentioned problems, the present invention achieves strong conveyance of the transfer material by effectively using the charged charge of the conveyor belt without using any special means for the charging device, regardless of the decrease in the electrical resistance of the transfer material. However, it is an object of the present invention to provide a transfer/conveyance device that can obtain a high-quality transferred image without going through a complicated static elimination operation.

Means for Solving the Problems In order to solve the above problems, the present invention monitors the physical quantity corresponding to the electrical resistance of the charged dielectric portion of the transfer material and the transfer material, and switches the polarity accordingly. The conveyor belt is configured to pass between a two-layer conductor belt connected to a bias power source for controlling the output, and a grounded conductive member provided in contact with the conveyor belt prior to the transfer position. It is something.

By adopting the above structure, the present invention first transfers a portion of the charge accumulated on the dielectric surface to the transfer material when the transfer material conveying belt is charged, and then monitors the electric resistance of this and the transfer material to adjust the output voltage. By attracting charges of opposite polarity to the dielectric part induced in the belt conductor connected to the controlling bias power supply, strong electrostatic adhesion between the transfer material and the conveyor belt is achieved, preventing misalignment during transfer. This allows the transfer material to be conveyed stably without any problems. At this time, by changing the bias polarity and output of the belt conductor layer in accordance with changes in the electrical resistance of the transfer material, the transfer material always retains a charge above a certain level, and stable conveying force can be achieved in any environment. . Furthermore, in a transfer method in which an image using charged particles is electrostatically transferred, the charge transferred to the transfer material strongly attracts the charged particles, making it possible to prevent image disturbance even when the conveyance belt and the transfer material are separated. Furthermore, 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 pose a major problem.

Embodiment Hereinafter, a transfer/conveyance device which is an embodiment of the present invention will be described with reference to the drawings. FIG. 1 shows a cross section of a transfer/conveyance device in a first embodiment of the present invention.

In FIG. 1, reference numeral 1 is a rotatable drum-shaped image holding member (hereinafter simply referred to as a drum), in which a photosensitive dielectric material such as selenium is layered on a drum-shaped conductor support such as aluminum. It has been established. Usually this conductor support is grounded. First, this drum 1) is the charger 1
The drum 1) is uniformly charged by the drum 1), and in the next exposure section 13, light that matches the original is imaged onto the drum 1) through a means (not shown), such as a lens. At this time, while the drum surface is uniformly charged, the charges on the parts exposed to light disappear by being neutralized with charges of opposite polarity induced in the conductor support on the back side of the photosensitive layer. A pattern of charges corresponding to the brightness and darkness of the original, that is, a latent image, is formed. This latent image is subsequently processed into fine charged particles (hereinafter referred to as toner) in the developing section 14.

) is visualized by the electrostatic force between The toner image thus obtained on the drum 1) is transferred to the transfer material 1, which is conveyed in synchronization with the toner image, at a transfer position 15.
) 7 (hereinafter referred to as paper),
The remaining toner on the drum 1) is wiped away by means such as a blade in the cleaning section 16, and then uniformly irradiated with a static eliminating light in the static eliminating section 17 to eliminate static electricity on the drum 1) before proceeding to the next process. Be prepared.

Here, part A is a transfer/conveyance device for paper, etc. according to the present invention. 1) 1 is composed of two layers: a dielectric layer 1) 2 on the outside and a conductive layer 1) 3 on the inside. In this example, the thickness is 9.
A sheet with a two-layer structure in which aluminum was vapor-deposited on one side of a 0 μm polyester film was cut out to a predetermined size, and the ends were welded using ultrasonic waves.

Of course, the outside may be made of vAit material such as nylon or Teflon, and its thickness is suitably 10 μm to 200 μm. The material of the inner layer does not matter as long as it is a conductor, and its thickness is arbitrarily determined depending on the mechanical strength of the belt together with the dielectric layer. Furthermore, a belt can be formed as a single sheet by gluing dielectric and conductor sheets together, or a dielectric layer can be formed by coating, gluing, dipping, etc. on a seamless endless conductor belt. In practice, there is no problem.

The belt 1) 1 is supported by rollers 1) 4, 1) 5 and stretched by means (not shown) of tension, such as a spring. The surface of the roller 1) 5 is made of a conductor,
Belt 1) Inside conductor l of 1 1) 3 is the above roller 1
) 5 to a power source 123 whose output is variable. Belt 1) 1 is rotated by a roller 1 by a rotating means (not shown).
) 5, the transfer unit 15 is rotated in the same direction of operation as the drum 1) and at the same circumferential speed. The surface of the dielectric portion 1) 2 outside the conveyor belt is charged by a charging corotron 1) 6 to a polarity opposite to that of the toner.

For example, if the toner is negatively charged, the dielectric part of bell l-1) 1 is positively charged, and the electric field based on this positive charge removes the toner on the surface of drum 1) from bell) 1) 1 side. This is because the image is transferred electrostatically to the image.

Here, the drum 1) 7 is sent between the roller 1) 4 and the grounded conductive rubber roller 1) 8 in synchronization with the drum 1). In this embodiment, conductive rubber roller 1
) 8 has a volume resistance of approximately 1ObΩ, and is strongly pressed against the roller 1) 4 by sandwiching the belt 1) 1 by means not shown.

When Gio 1) 7 passes between the conductive rubber roller 1) 8 and belt 1) 10 and is brought into close contact with the belt 1) 1, the electrically charged surface of the dielectric part 1) 2 of the belt 1) 1 is transferred to Gio 1) 7. Charge flows into it. At this time, how much the paper is charged depends on the capacitance and resistance of the air gear layer at the interface between belt 1) 1, paper 1) 7, and the conductive rubber roller, or the belt, paper, and conductive rubber roller, and the belt conductor layer. Connected DC current 1
23 polarity and output voltage, and conductive rubber roller 1) 8
Belt 1) Nip width when pressing on 1, Bel I-1) 1
determined by the circumferential speed of FIG. 2 shows an equivalent circuit in which the ON state of Sw corresponds to when the belt 1) 7 is passing between the belt 1) 1 and the conductive rubber roller 1) 8.

It is known that the electrical resistance and capacitance of paper vary greatly depending on the external environment, and especially in high humidity, the electrical resistance of paper decreases significantly and it becomes difficult to retain charge, making it difficult to expect stable conveyance. It disappears. In this FIG. 2, Q (b) is the amount of charge per unit area held by the belt 1) 1 before reaching the conductive rubber roller 1) 8, Cb,
Cp, Ca.

Cr is Bel per unit area +-iit, 1)
7. The capacitance of the air gap layer and the conductive rubber roller 1) 8. Rp, Ra, and Rr are the volume resistivity of the air gap layer and the conductive rubber roller 1) 8 per unit area, respectively. indicates the voltage of the bias power supply 123.

At this time, the distribution of charges on paper 1) 7 and the belt dielectric surface is shown in the third diagram.
As shown in the figure. Here, a bias power supply 123 is applied to the belt conductor layer.
By adding , it is possible to cancel the above-mentioned fluctuation in the amount of charge movement caused by the fluctuation in the electrical resistance of the paper. Regarding the polarity of the DC power supply, for example, if the electrical resistance of the paper decreases due to high humidity, the time constant of the charge leaking from the belt will become smaller, so the initial charge transfer from the belt should be kept small. . This can be done in the direction of lowering the potential on the surface of the belt dielectric when viewed from the grounding position, that is, if the belt is positively charged, it should be set to negative polarity, and if it is negatively charged, it should be set to positive polarity. Paper 1) 7 and Bell) 1) under high humidity when bias is applied to the belt conductor layer in this way.
The charge distribution at 1 is shown in FIG. Bias power supply 123
The output of 7 is approximately 10 μC/n (although it is not necessary to consider various variables of the equivalent circuit in Fig. 2).
All you have to do is make it more than that. Here, by changing the bias output of the belt conductor layer in accordance with the decrease in the electrical resistance of the belt 1) 7, a constant and stable conveying force can be realized regardless of the change in the electrical resistance of the belt 1) 7. I can do it. At this time, the electrical resistance monitor of Gio 1) 7 was the first one.
This is done by the surface potential sensor 122 shown in the figure, and always
) The bias output may be changed so that the surface potential of 7 remains above a certain level even in a high humidity environment, or the bias output may be controlled using a sensor that monitors a physical quantity different from that shown in Figure 1. It's okay.

In addition, if the electrical resistance of the paper 1) 7 increases due to low humidity, simply grounding the belt conductor layer 1) 3 will prevent the belt dielectric layer 1) 2, the paper 1) 7, the conductive rubber roller 1) 8 If the paper 1
) 7 has a small capacitance, the charge remaining on the belt dielectric layer is larger than that of paper, so 1) 7 is the conveyor belt 1) 1
Image distortion occurs when the image is separated from the image. At this time, it is sufficient to apply a bias in the direction of pushing up the potential of the belt dielectric as viewed from the ground position, contrary to the case of high humidity.

At this time, the electrostatic attraction between the belt conductor part 1) 3 and the belt 1) 7 is the product of the electric field strength E applied to the belt dielectric part 1) 3 and the amount of charge Qp of the belt 1) 7. From this, the charge Qp transferred to Gio 1) 7 by the conductive rubber roller 1) 8
The greater the number, the stronger the adsorption force will be generated. Therefore, the conductive rubber roller 1) 8 is used to transfer charges from the belt 1) 1 to the paper 1) 7, and if it is a conductive member, the same effect can be expected regardless of the material and shape.

In this way, Gion 1) 7, which was strongly attracted to belt 1) 1, reaches the transfer position 15 without worrying about falling off or slipping, and belt 1)
Due to the electric field created by the charges of opposite polarity to the toner distributed on the drums 1 and 1), the toner image on the drum 1) and the drum 1) is electrostatically transferred from above the drum 1) facing the drum 1).

After the transfer, the paper 1) 7 is separated without the need for any special equipment due to the adsorption force between the paper 1) 7 and the belt 1) 1 and the rigidity of the paper 1) 7 itself, and the paper 1) 7 is separated from the belt 1). Finish the transfer while keeping it in close contact with 1.

After that, the belt 1) 1 and the paper 1) 7 are separated by the curvature of the roller 1) 5 and the rigidity of the paper 1) 7, and the receiver is passed to the fixing guide 1) 9, and passes through the fixing device 120 as shown in the figure. The paper is transported to the paper output tray, and copying is completed.

U.S. Pat. No. 3,717,801 discloses that the charges on the charged dielectric belt and the charges on the toner on the paper 1) attract each other, and when the belt 1) 7 and the belt 1) 1 are separated, the toner moves in the traveling direction. The problem of causing image disturbances that scatter backwards has been taken up. As a countermeasure to this, U.S. Patent No. 3.717
, No. 801, a special operation is performed on the charging method. Furthermore, several methods have been proposed in which electricity is removed from the paper and the dielectric at a position where the paper and the belt are separated. However, by adopting the configuration of the present invention, the charge transferred to the paper itself strongly attracts the toner even after the belt and paper are separated, so a high-quality transferred image can be obtained without the need for a special charge eliminator. .

Further, in FIG. 1, reference numeral 121 denotes a belt cleaning device, which removes toner electrostatically by applying a bias of polarity opposite to that of the toner to a conductive fur brush, for example. It has been experimentally confirmed that when cleaning the toner adhering to the belt 1) 1, the lower the amount of charge on the heald 1) 1, the lower the bias voltage applied to the fur brush and the more efficient cleaning can be performed.

In the configuration shown in Figure 1, the conductive rubber roller 1) 8 is the belt 1) 1.
It has been found that this method has a significant effect on cleaning performance by transferring the charge of 1) to 7 and reducing the amount of charge of 1) 1 itself.

In the embodiment shown in FIG. 1, the paper 1) 7 is configured to pass above the drum 1), but it is also possible to adopt a structure in which the paper 1) 7 is passed to the side or below the drum 1).

Further, in this embodiment, an electrophotographic copying apparatus is taken as an example, but the conveyance method according to the present invention can also be applied to a transfer/conveyance apparatus used in combination with other transfer methods, such as a transfer method that performs thermal transfer. It is possible.

Effects of the Invention As described above, the present invention consists of two layers of conductors connected to a bias power source that monitors the electrical resistance of a dielectric material such as paper and a transfer material and changes the output voltage according to the results. The transfer material is fed between a belt consisting of a belt and a grounded conductive member provided in contact with the belt prior to the transfer position. The belt is charged with a charge above a certain level even in the environment, strongly adsorbs the transfer material, performs stable conveyance and reliable transfer without deviation, and produces a good belt without image distortion without the need for any special static eliminator. The transfer material can be separated and the toner attached to the belt can be efficiently cleaned.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a transfer/conveyance device according to an embodiment of the present invention. Figure 2 shows an equivalent circuit for explaining the transfer of charges from the charged transfer/transport belt to the transfer material according to this embodiment, and Figure 3 shows the resistance of the transfer material when the rollers 1) and 8 are directly grounded. FIG. 3 is a schematic diagram showing a state in which most of the charge is lost from the transfer/conveyance belt and the transfer material due to low charge. FIG. 4 is a schematic diagram showing the effect of bias on the charge distribution when a transfer material having the same resistance as that in FIG. 3 is transported by the transfer/transport device according to this embodiment. FIG. 5 is a schematic diagram of a known transfer material conveying device using electrostatic force. FIG. 6 is a schematic diagram of a known transfer material conveying device that utilizes electrostatic force. 1)...Drum, 12...Charger, 1
3...Exposure section, 14...Development section, 15
...Transfer section, 16...Cleaning section, 17...Static charge removal section, 1)1...Transfer section
Conveyor belt, 1) 2...Belt dielectric layer, 1)
3... Belt conductor layer, 1) 4... Driven roller, 1) 5... Drive roller, 1) 6
...Charger, 1)7...Transfer material, 1)
8... Conductive roller, 1) 9... Fixing guide, 120... Fixing device, 121...
...Conductive fur brush for cleaning, 122...
... surface potential sensor, 123 ... variable output DC power supply, 124 ... bias output control device. Name of agent: Patent attorney Toshio Nakao (1 person) Figure 1 Figure 2 δW Figure 4

Claims (2)

[Claims] (1) In a device that electrostatically supports and conveys a sheet-like or continuous transfer material in the traveling direction using an endless transfer material conveying belt and physically or chemically transfers an image to the transfer material, The transfer material conveyance belt has a surface in contact with the transfer material made of a dielectric material and a back surface made of a conductive material, and includes means for supporting and extending the transfer material conveyance belt and rotating in a fixed direction at a constant speed; means for charging a dielectric portion of the transfer material conveying belt; means for applying a bias whose polarity can be switched with the belt dielectric portion and whose output voltage is variable; means for monitoring a physical quantity corresponding to the electrical resistance of the transfer material; means for controlling the bias output voltage accordingly; 1. A transfer/conveying device characterized by comprising means for feeding through a grounded conductive member disposed prior to the position. (2) When transferring charged particles electrostatically, the output of the bias is 10 μC/
The transfer/conveyance device according to claim (1), wherein the transfer/conveyance device is set to be charged to m^2 or more.