JPS62215979A - Transfer and carrying device - Google Patents

Abstract

PURPOSE:To satisfactorily and stably carry a transfer material without being influenced by the variation of an environment, by controlling a bias voltage applied to a conductive member for monitoring an electric resistance of the transfer material and feeding the transfer material together with a necessary transfer belt. CONSTITUTION:A transfer material 117 is fed by a carrying belt 111 which is formed by a dielectric layer 112 whose surface is electrified by an electrifier 116, and a carrying belt 111 whose rear side is connected to a ground, and the roller 118 of a conductive member. An electric resistance which is varied by the environment of this transfer material 117 is monitored by a surface potential sensor 122. Subsequently, in accordance wit the result of monitoring, a bias voltage applied to the roller 118 through a bias output controller 124, and its polarity are controlled, and the transfer material 117 is electrified properly. As a result, the transfer material 117 is adsorbed strongly to the belt 111, and under any environment, the transfer material is carried satisfactorily and stably, and the transfer image having a good quality being free from a dislocation 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, in US Pat. No. 2,667B82, a conductive member and a dielectric member are bonded together to form a two-layer conveyor belt, and a transfer material is supplied between the conveyor belt and a charging member. For this reason, it can be seen as a method in which the paper is charged and then attracted to the belt, rather than being attracted to a pre-charged belt.

FIG. 6 shows this embodiment. A dielectric belt 61 is supported and stretched by rollers 52 and 63. A metal belt 64 is supported by rollers 66 and 67. 6
A metal foil 6 faces the metal belt 64 with the dielectric belt 61 in between. The transfer material 68 is charged by the bias applied between the metal belt 64 and the metal foil 66.

Reference numeral 69 short-circuits the metal foil 66 and the transfer material 68.

610 is a guide plate that guides the transfer material 68 to the belt 51.

In US 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. 6 shows a schematic diagram of the embodiment. 61 is a drum-shaped image support, 62 is a dielectric single layer bell), 63.6
4 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, although the belt in U.S. Pat. When performing transfer, it is necessary to provide a plurality of independent corona dischargers dedicated to transfer at the transfer position. Further, in U.S. Pat. No. 2,578,882, it is possible to perform transfer and conveyance by combining charging devices, but due to the structure, the former U.S. Pat. No. 3,3573
Similar to Publication No. 28, when the conveyor belt and the transfer material are charged to the extent that sufficient conveyance force is obtained, the charge that is electrostatically transferred onto the transfer material when the transfer material and the conveyor belt are separated is It is extremely likely that the particles will be disturbed and have an adverse effect on the transferred image. For this reason, in a conventional transfer device using a transfer/conveyance belt, it is essential to perform an operation to eliminate electric charges existing on the belt and the transfer material at a separation position between the transfer material and the conveyance belt. However, it is extremely difficult to completely remove all of the charges existing on the conveyor belt and the transfer material, and to do so, it is necessary to use a separate discharger connected to a special power source for charge removal. This is shown in US Pat. No. 3,244,083, etc. Additionally, U.S. Pat.
Although this method is disclosed in Japanese Patent No. 17801, etc., it is difficult to say that it is a preferable method in view of economic reasons. Additionally, U.S. Patent No. 2576
In Japanese Patent No. 882, if the transfer material is curled, there is concern about the conveyance performance. Further, in the above configuration, no consideration was given to the fact that the conveying force and transfer efficiency were 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 uses a conveyor belt consisting of two layers: a dielectric portion on which the transfer material is charged and a conductor connected to ground or an arbitrary bias power supply; A conductive member connected to a DC power supply that monitors the physical quantity equivalent to the electrical resistance of the transfer material and can switch polarity and control output accordingly, which is provided in contact with the transfer material prior to positioning. It is designed to pass between the two.

By adopting the above-mentioned structure, the present invention first transfers a portion of the electric charge accumulated on the dielectric surface to the transfer material when the transfer material conveying belt is charged, and transfers the electric charge induced in the belt conductor which is grounded or biased. By attracting charges of opposite polarity to the dielectric part of the transfer belt, strong electrostatic adhesion between the transfer material and the conveyor belt is achieved, and the transfer material is conveyed stably without shifting during transfer. . At this time, by changing the polarity and output of the DC power supply connected to the conductive member in accordance with changes in the electrical resistance of the transfer material, the transfer material always retains a charge above a certain level, making it stable in any environment. Conveying power can be achieved. 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. In addition, 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 is not a big problem. Refer to and explain. FIG. 1 shows a cross section of a transfer/conveyance device in a 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), in which a photosensitive dielectric layer such as selenium is coated on a drum-shaped conductor support such as aluminum. It was established. Usually this conductor support is grounded. First, this drum 11 is a charger 1
2, the original corresponding to the document is imaged onto the drum 11 through means (not shown), such as a lens, in the next exposure section 13. At this time, while the drum surface is uniformly charged, the charges on the most exposed parts 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 11 is transferred to the transfer material 1 which is conveyed in synchronization with the toner image at the transfer position 15.
17 (hereinafter referred to as paper),
The remaining toner on the drum 11 is wiped off 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 11 and prepare it for the next process. .

Here, the mu section is a transfer/conveyance device for paper, etc. according to the present invention. The belt 111 is composed of two layers: a dielectric layer 112 on the outside and a conductor layer 113 on the inside. In this example, the thickness is 90
A sheet of two-layer structure in which aluminum was vapor-deposited on one side of a μm polyester film was cut out to a predetermined size and the ends were welded using ultrasonic waves. Of course, the outside can be made of dielectric material such as nylon or Teflon, and its thickness is 10%.
A suitable thickness is from μm to 200 μm. The inner layer may be made of any material 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 111 is supported by rollers 114 and 116, and is stretched by means (not shown) using tension such as a spring. The surface of the roller 116 is made of a conductor,
The conductor layer 113 inside the belt 111 is connected to the roller 11
It is grounded through 6. An appropriate bias may be added depending on the situation. The belt 111 is rotated by driving a roller 115 by a rotating means (not shown) so that the direction of movement in the transfer section 16 is the same as that of the drum 11 and the circumferential speed is the same. The surface of the dielectric portion 112 outside the conveyor belt is charged by a charging corotron 116 to a polarity opposite to that of the toner. For example, if the toner is negatively charged, the dielectric portion of the belt 111 is positively charged.
This is because the toner on the surface of the drum 11 is electrostatically transferred to the belt 111 side by an electric field based on this positive charge.

Here, the paper 117 is connected to a DC power source 123 that controls the polarity and output voltage by monitoring the physical quantity corresponding to the electrical resistance of the roller 114 and the transfer material in synchronization with the drum 11.
and a conductive rubber roller 118 connected to the conductive rubber roller 118. In this embodiment, the conductive rubber roller 118 has a volume resistance of about 106 Ω, and is strongly pressed against the roller 114 with the belt 111 sandwiched therebetween by means not shown.

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, charges flow into the paper 11 from the charged surface of the dielectric portion 112 of the belt 111. At this time, how much the paper is charged is belt 111, paper 117, and 4! The capacitance and resistance of the air gap layer at the interface between the rubber roller or the belt, paper, and the conductive rubber roller, the polarity and output voltage of the DC power supply 123 connected to the conductive rubber roller, and the conductive rubber roller 11
Nip width when pressing 8 to belt 111, belt 111
determined by the circumferential speed of

FIG. 2 shows an equivalent circuit, and the ON state of Sw corresponds to when the paper 117 is passing between the belt 111 and the conductive rubber roller 118.

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 transport. It disappears. In this FIG. 2, Q(b) is the amount of charge per unit area held by the belt 111 before reaching the conductive rubber roller 118, and Cb, O
p, Ca, Cr are each Bel per unit area) 111
, paper 117° air gap layer, conductive rubber roller 11
Rp, RIL, and Rr are the volume resistances of the paper per unit area, the air gap layer, and the conductive rubber roller 118, respectively, and ■ is the voltage of the DC bias power supply 123.

The distribution of charges on the paper 117 and the belt dielectric surface at this time is shown in the third diagram.
As shown in the figure. By applying a bias to the conductive rubber roller, 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. As for 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 paper will become smaller, so the initial charge transfer from the belt should be kept small. good. This can be done in the direction of increasing the potential on the surface of the belt dielectric when viewed from the ground position, that is, if the belt is positively charged, the polarity is positive, and if the belt is negatively charged, it is negative polarity. In this way, the bias power supply 12 is applied to the belt conductor layer.
FIG. 4 shows the charge distribution on the paper 117 and the belt 111 under high humidity when a voltage of 3 was applied. Although the bias output must take into consideration various variables of the equivalent circuit shown in FIG. 2, it is sufficient to set the amount of charge on the paper 117 to approximately 10 μO/d or more. Here, by changing the output of the bias power supply 123 of the belt conductor layer in accordance with the decrease in the electrical resistance of the paper 117, it is possible to realize a constant and stable conveying force regardless of the decrease in the electrical resistance of the paper 117. can.

At this time, the electrical resistance of the paper 117 is monitored by the surface potential sensor 122 shown in FIG. Alternatively, the bias output may be controlled using a sensor that monitors a physical quantity other than that shown in FIG.

In addition, when the electrical resistance of the paper 117 increases due to low humidity, the conductive rubber roller 118 is simply grounded. Snoring 117. Conductive rubber roller 1
If the capacitance of the paper 117 is small, the charge remaining on the belt dielectric layer is larger than that of the paper, so when the paper 11γ is separated from the conveyor belt 111, This will cause image distortion. At this time, it is sufficient to apply a bias in the direction of lowering the potential of the conductive rubber roller 118 when viewed from the ground position, contrary to the case of high humidity.

At this time, the electrostatic attraction between the belt conductor part 113 and the paper 117 is the product of the electric field strength E applied to the belt dielectric part 113 and the amount of charge Qp of the paper 117.

From this, the paper 117 is removed by the conductive rubber roller 118.
The more charges Qp that move, the stronger the adsorption force will be generated. Therefore, the conductive rubber roller 118
This is to transfer the charge from the paper 117 to the paper 117, and if it is a conductive member, the same effect can be expected regardless of the material and shape. In this way, the paper 1 strongly attracted to the belt 111
17 reaches the transfer position 15 without fear of falling off or slipping, and is transferred to the drum 1 facing the belt 111 and paper 117 by an electric field created by charges of opposite polarity to the toner distributed on the paper 117.
A toner image is electrostatically transferred onto the paper 117 from above.

After the transfer, the paper 117 is separated without any special device due to the adsorption force between the paper 117 and the belt 111 and the rigidity of the paper 11 itself, and the transfer is completed while the paper 117 remains in close contact with the belt 111.

Thereafter, the belt 111 and the paper 117 are separated by the curvature of the roller 116 and the rigidity of the paper 117 itself, and the paper is transferred to the fixing guide 119, passed through the fixing device 120, and conveyed to a paper output tray (not shown) for copying. Complete. US Patent 37
Publication No. 17801 deals with the problem that the charges on the charged dielectric belt and the charges on the toner on the paper 117 attract each other, and when the paper 117 and the belt 111 are separated, the toner scatters backward in the traveling direction, causing image disturbance. There is. As a countermeasure to this problem, US Pat. No. 3,717,801 uses a special 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 adhesion IJ-ning device, which electrostatically removes toner by applying a bias of the opposite polarity to the toner to a conductive fur brush, for example. When cleaning the toner attached to the belt 111, the belt 11
It has been experimentally confirmed that the lower the charge amount of No. 1, the more efficient cleaning can be performed with a lower bias voltage applied to the fur brush. In the configuration shown in FIG. 1, the conductive rubber roller 118 transfers the charge on the belt 111 to the paper 117,
It has been found that reducing the amount of charge on the paper 117 has a significant effect on cleaning performance. In the embodiment shown in FIG. 1, the paper 117 is passed above the drum 11. It is also possible to have a structure in which it passes through the side or below the drum 11.

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 is provided with a belt consisting of two layers: a dielectric material such as paper that is charged and a conductive material that is grounded or in a biased state, and is brought into contact with this belt prior to the transfer position. , a configuration in which the transfer material is fed between a conductive member connected to a DC voltage power source that monitors a physical quantity equivalent to the electrical resistance of the transfer material and changes the output voltage according to the result. The belt dielectric section charges the paper with an electric charge above a certain level in any environment, strongly adsorbs the transfer material, and performs stable conveyance and reliable transfer without shifting, without the need for any special static eliminator. The belt and transfer material can be separated well without image disturbance, and the toner adhering to the belt can be efficiently removed.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a transfer/conveyance device according to an embodiment of the present invention, and FIG. 2 is an equivalent circuit diagram for explaining the transfer of electric charge from a charged transfer/conveyance belt to a transfer material according to this embodiment. FIG. 3 is a schematic diagram showing a state in which when the roller 11B is directly grounded, the resistance of the transfer material is low and most of the charge is lost from the transfer/conveyance belt and the transfer material. FIG.・A schematic diagram showing the effect of bias on the charge distribution when a transfer material with the same resistance as that shown in Figure 3 is conveyed by a conveyance device. Figure 6 is a schematic diagram of a known transfer material conveyance device that uses electrostatic force. 6 are schematic diagrams of a known transfer material conveying device that utilizes electrostatic force. 11...Drum, 12...Charger, 1
3...Exposure section, 14...Development section, 16
...Transfer section, 16...Cleaning section, 17...Static elimination section, 111...Transfer section
Conveyor belt, 112... Belt dielectric layer, 11
3... Belt conductor layer, 114... Driven roller, 116... Drive roller, 11
6... Charger, 11 completed... Transfer material, 1
18... Conductive roller, 119...
Fixing guide, 12o...Fuser, 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 and 1 other person 2nd
Figure W Figure 4 Figure 5, S Figure 6

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 electrically charging a dielectric portion of the transfer material conveying belt; means for grounding or applying a desired bias to a conductive portion of the transfer material conveying belt; A means for supplying a transfer material between a conductive member placed prior to the transfer position, a means for monitoring a physical quantity corresponding to a resistance value of the transfer material, and a means connected to the conductive member in accordance with this. A transfer/conveying device characterized by comprising means for controlling the polarity and output voltage of a DC power source. (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.