JPH01244485A - Transfer/conveyance device - Google Patents

Abstract

PURPOSE:To prevent the fluctuation of the resistance value of the surface of a conveying belt due to heating of a fixing device by boosting the electrical resistance of the surface brought into contact with the conveying belt for transfer material in a prescribed position. CONSTITUTION:A corona electrostatic charger 17 conveys the transfer material 8 on which a toner image is formed with the aid of a conductive, endless conveying belt 9, then separates it from the belt 9. Before the belt reaches a fixing device 16 equipped with a heating means 14, a halogen lamp 15, etc., the electrical resistance of the surface of the material 8 brought into contact with the belt 9 is raised. Even if the electrical resistance of the surface on which a toner image is formed rises due to the heating of the means 14, etc., the charge holding property of the material 8 is improved when it is used for continuously forming color images. As a result, the electrostatic adhesiveness between the material 8 and the belt 9 is maintained greatly and constantly; therefore the conveyance of the material 8, image transfer and the separation of the material from the photosensitive drum 1 are enhanced to improve reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a transfer method in which a toner image on a toner image carrier is transferred to a transfer material by physical or chemical means by electrostatically supporting and transporting a transfer material. - Concerning conveyance equipment.

Conventional technology In electrophotographic copying machines and electrophotographic printers, belts are made of insulating materials such as dielectrics in order to ensure transportability of the transfer material and separation of the toner image from the toner image carrier. However, there is known a means for conveying a transfer material by electrostatically bringing it into close contact with the transfer material.

US Pat. No. 3,357,325 uses a corona charger to attract and transfer a transfer material, and proposes a method using a dielectric single-layer belt. FIG. 2 shows a schematic diagram of a conventional example. 21 is a drum-shaped toner image carrier, 22 is a dielectric single-layer belt, and 23 and 24 are rolls for supporting, stretching, and rotating the dielectric belt 22. 25 transfer material 2
27 is a corona charger for adhering the transfer material 2G to the dielectric belt 22 by electrostatic force, and 28 is a roll for transferring the toner image from the image support 21 to the transfer material 26. It is a corona charger.

Japanese Unexamined Patent Publication No. Sho 54-58034 No. Q A proposal is shown in which the corona charger for adsorbing a transfer material in the above example is deleted. The content of the proposal is divided into two depending on the resistance value of the belt component feed.・Resistance value range is 108~1011Ω
・For cm ・Resistance value range is 101 Ω・cm or more, belt thickness is 150μ or less, and saturation charging potential is 2500
This is the case when the value is less than or equal to v. FIG. 3 shows a schematic diagram of a conventional example. The drum 30 charged by the corona charger 29 is exposed to light by the optical system 31 to form a latent image, and the developing device 32 forms a toner image. The toner image is transferred to a transfer key 435 conveyed by the belt 34 of the separation belt device 33 by a transfer corona charger 37 connected to a DC power source 36. After conveying the transfer material 35, the bell 1-34 is neutralized by an alternating current or 10-na charger 38 having a polarity opposite to that of the bell I charger. In order to assist in the separation of the transfer material from the tram, an AC type 1fA39 of 1 to 10 kv is connected in series to the 1 to IQk,v DC power supply of the transfer corona charger as shown in Fig. 4. Alternatively, as shown in FIG. 5, a separate corona charger 41 connected to a separate power source 40, which is an AC power source or a DC power source with a polarity opposite to that of the charging polarity, is arranged downstream of the transfer corona charger 37 when the belt travels. The method is shown7.

Problems to be Solved by the Invention However, the belt proposed in U.S. Pat. be. The capacitance C of the belt is given by the dielectric constant ε and the belt thickness d, and the capacitance per unit area NC is given by C-=ε/d. If you want to obtain a capacity of about LOOpF per unit area as the same capacity as the normal organic belt (ε-2 to 4)
The thickness is 20 to 40μ. With this thickness, the practical strength of the conveyor belt I/closing is weak, so if the belt is several hundred microns thick, sufficient capacity cannot be obtained, and the amount of charge held by the belt is low. Because of the small amount of paper, a corona charger dedicated to transfer is provided at the transfer position, but the transfer ability is weak. This point is also stated in the above-mentioned Japanese Patent Application Laid-Open No. 54-58034, and especially when used continuously, the surface potential of the bell 1 increases,
This is also Japanese Patent Application Publication No. 54. -58034 Moderator tU & This is not practical for transcription due to its obvious drawbacks. Further, when the Bell I/surface potential is changed, the adsorption force of the transfer material also decreases in proportion to it. Furthermore, from the perspective of transfer ability, the polarity of the corona charger for adsorbing the transfer material to the belt surface is the same as that of the 1-ner, so if the resistance value of the transfer material decreases due to moisture absorption, etc. (If the transfer material used to be paper-threaded, the volume resistivity would be approximately 10 due to the influence of environmental humidity.)
The charging current (which varies in the range of 8 to 1011 Ω·cm) flows through the transfer material, which greatly inhibits transferability.

In addition, when organic materials are irradiated with corona discharge for a long period of time, a modified layer is generated in the molecular structure of the surface layer, and when moisture is absorbed, the surface resistance decreases significantly and charge retention is lost, so there are also weaknesses in this respect. It is a method. On the other hand, Japanese Patent Application Publication No. 1973
-The proposal in Publication No. 58034 has a resistance value range of 1011Ω.
・cm or more] In the case where the belt thickness is 150μ or less and the saturation charging potential is 2500V or less, an increase in the belt surface potential during continuous use is prevented by installing a static eliminating corona charger 3B. However, in the third example, the transfer current flowing from the corona charger 37 to the tram 30 flows from the belt 34 to the transfer material 35 to the drum 30, so the adsorption force between the belt and the transfer material is equal to the adsorption force between the transfer material and the drum. Therefore, there is no element that causes any force that would easily cause the transfer material to separate from the drum. If separation occurs, it is due to the stiffness of the transfer material that resists bending against the curvature of the drum, and if the stiffness of the transfer material is small or the drum diameter is large, the probability of separation is about the same. For this reason, proposals shown in FIGS. 4 and 5 have been made to assist in separability, but these proposals all aim to reduce the transferability of toner images.
In particular, if the transfer material is paper and absorbs moisture and its resistance value decreases, this will lead to poor transfer. Furthermore, when an AC power source is used, it is economically disadvantageous due to the high cost of the power source.

In addition, even when the resistance value range is IO8 to 101Ω・cm, there are no particularly excellent factors regarding the separability of the transfer material as in “-1”, and the belt thickness is This is the same as in the case of 150μ or less.

In particular, monochrome copying machines and digital color copying machines using electrophotographic printers, which have recently become widely used,
When the transfer material is paper and color composite copying is performed multiple times on the same copying surface, the transfer material adheres closely to the toner image carrier without separating from the toner image carrier during the multiple copies. They become entangled, often causing copying problems. This phenomenon occurs even with thick transfer materials with high rigidity, and when the phenomenon is observed in detail, the effect of the heated roll type fixing device used in this type of copying machine is transferred to the heated roll side (A copy) Since the moisture on the surface of the transfer material on the hack-up roll side is lower than the moisture on the surface of the transfer material on the hack-up roll side, the surface resistance value increases and becomes greater than the adhesion between the drum and the transfer material or the adhesion between the belt and the transfer material. It was found that poor separation occurred, and in the case of the conventional example mentioned above, it was clearly seen that the adhesion between the belt and the transfer material was inadequate.

In view of the above problems, the present invention effectively utilizes the charging characteristics of the conveyor belt and the transfer material to achieve strong separation and conveyance of the transfer material by controlling the electrical resistance value of the transfer material, thereby achieving high-quality transfer. An object of the present invention is to provide a transfer/conveyance device for obtaining an image.

Means for Solving the Problems In order to solve the above problems, the present invention provides a means for supporting and extending an endless transfer material conveying belt I made of a conductor and rotating it in a fixed direction, and a means for rotating it in a fixed direction. A transfer means that has a corona charger on the back side and transfers the toner image onto the transfer material while sandwiching the transfer +1 between the toner image holder and the transfer material transport belt on the front side of the material transport belt, and a belt running of the transfer means. A transfer/conveyance device comprising at least a means for separating the transfer material from the transfer material conveyance belt on the downstream side, after the transfer material is separated from the transfer + old general conveyance belt, but before the toner on the transfer material is fixed. In addition, a means for increasing the electrical resistance of the surface of the transfer material that was in contact with the conveyor belt is added.

By adopting the above-mentioned structure, the present invention reduces the electrical resistance on the back side of the transfer material after the transfer material is separated from the transfer material conveyance belt and before being transported to the fixing means for fixing the toner on the transfer material. Therefore, when the paper is fed for the next multiple copies, it comes into close contact with the conveyor belt 1- because it retains the charge. The electrostatic adhesion between the transfer material and the toner image carrier is always kept large, and the separability of the transfer material from the toner image carrier becomes highly reliable.

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 an electrophotographic printer equipped with a transfer/conveyance device according to the present invention. In FIG. 1, reference numeral 1 denotes a rotatable drum-shaped I/toner image holder (hereinafter simply referred to as a drum);
For example, a photosensitive dielectric layer such as selenium is provided on a tram-shaped conductor support such as aluminum. Usually this conductor support is 'grounded'. First, this tram 1 is uniformly charged by a charger 2, and in the next exposure section 3, light corresponding to the print I/document is emitted by means (not shown) such as a semiconductor laser, an LEI) array, a liquid crystal shutter array, and a lens optical system. etc., and is imaged onto the tram 1. At this time, -
The electric charge on the drum surface exposed to light is neutralized with the opposite polarity electric charge induced in the conductor support on the back side of the photosensitive layer, and the electric charge disappears, corresponding to the original to be printed. A buckoon of charge, or latent image, is formed. This latent image is then deposited with fine insulating charged particles (hereinafter referred to as 1-ner) by electrostatic force in the developing section 4.
Visualized. The toner image of the tram 1-1- thus obtained is electrostatically transferred by the transfer means 5 to the transfer material 8 conveyed in synchronization with the I-toner image, and the toner image of the tram 1-1- The remaining toner is removed from the cleaning section 6.
After the drum 1 is wiped away by means such as a blade, the charge eliminating section 7 directs a negative charge eliminating light to 1) to eliminate the charge on the drum 1, and the drum 1 is ready for the next printing process.

Next, a transfer/transport device for a transfer material such as paper according to the present invention, which is applied to the electrophotographic printer using the generally known toner described above, will be described in detail. In Figure 1, the conveyor belt 9 has a thickness of 0.6 fins and a volume resistivity of 5 x 1012Ω.
・cm carbon-dispersed polyurethane resin molded into an endless shape with a circumference of 380 ms was used. As mentioned above, the charge discharge time constant of the conveyor belt has a capacitance component of C-ε.
/d, if the resistivity is shifted from ρ, the resistance component R is given by R-ρd, so it becomes the time constant CR-ερ, and the time constant of the conveyor belt used here is ε-3, which is about 1.3 seconds. . Therefore, in 1.3 seconds, more than 70% of the charge is discharged by -1x, so if the same part of the belt does not pass through the transfer means 5 within this time, there is no need for a corona charger for charge removal. If the volume resistivity becomes too high, unnecessary electrification of the belt I~ as described above will occur, making it impossible to inject charge into the belt, resulting in poor transfer and poor adhesion of the transfer material to the belt. The belt 9 is a roll 10.1
1, and stretched by means (not shown) using tension such as springs. The surfaces of these rolls are made of a conductor and are grounded through the inside of the belt 9. An appropriate bias may be applied to this depending on the situation.

The belt 9 is rotated by driving the roll 10 or 11 by a rotational drive means (not shown) so that the direction of rotation and running at the transfer site where the transfer means 5 is located is the same as that of the tram 1 and the circumferential speed is the same. Here, drum peripheral speed 1
The speed was set at 601 II/sec. Therefore, the belt completes one rotation in approximately 2.4 seconds. A transfer corona charger 12 is installed inside the transfer region of the conveyor belt 9, and a high voltage Uzuki II is applied by a DC high voltage power source 13 of reverse polarity to transfer the toner onto the transfer material 8. This is because, for example, if the toner is positively charged, the transfer charger 12 is a negative electrode, and a transfer current flows to positively charge the negative charge on the back side of the bell 1-9. Based on the movement of charges, the toner on the surface of the drum 1 is transferred to the transfer material 8 present on the surface side of the bell l-9. Bell I with high electrical resistance or Bell 1 with a large discharge time constant
As mentioned above, if enough charge moves to charge the capacitance component of , transfer becomes impossible because no transfer current flows, but in the belt according to the present invention, after passing through the transfer site due to the resistance component, Since self-discharge is generated at the transfer site and a transfer current flows through this resistance component when reaching the transfer site, transfer can be assisted.

Furthermore, in electrophotographic printers, latent images are often developed by reversal development, and a corona charger for transfer is used with a polarity opposite to that of the drum 1. Due to rectification, if the transfer corona charger 12 is used to negatively charge the drum, an excessive transfer current may flow and cause the drum to deteriorate. However, if the belt is sandwiched between the belts and charged, the buffering effect of the resistance component of the belt will prevent the transfer. It is possible to reduce the current.

According to the present invention, the following structure needs to be added in a tree-like manner. That is, the transfer means 5 of the transfer material conveying belt
On the traveling downstream side of the transfer site where is located, the diameter of the belt support roll 11 is made smaller, and the transfer material is separated from the transfer material conveying belt I, which utilizes the rigidity of transfer A, and the transfer material is After the transfer material is separated from the belt, the heating means 14 is used to remove moisture contained in the transfer material or adsorbed to the transfer surface in order to increase the electrical resistance of the surface where the transfer material was in contact with the belt. The structure consists of: In addition, in order to easily separate the transfer material from the belt, a corona charger 1 is connected to the high-voltage electric current tA 18 in a manner opposite to the I call 11 in order to neutralize the electric charge that causes the transfer material to adhere to the belt.
7 may be installed. In this case, since the high-voltage power supplies 13 and 18 have the same polarity, there is no problem in simplifying the power supply by supplying them separately from the same high-voltage power supply.

From the viewpoint of transportability of the transfer material, the above-mentioned additional configuration improves the charge retention property of the transfer material on the side that contacts the belt, or in other words, increases the discharge time constant. As mentioned earlier, when transfer) A is ordinary paper, the resistance value fluctuates significantly, so the discharge time constant also changes accordingly, and the higher the resistance value, the better the charge retention. Even if the charge retention property on the conveyor belt side is slightly reduced, sufficient conveyance performance can be obtained. However, if the resistance value of the transfer material decreases and the The fixing means for the toner used in the electrophotographic process is, of course, to heat the surface on which the toner is placed to thermally fuse it to the surface of the transfer material. Since a method of fixing toner is generally adopted, the electric resistance on the front and back sides of the transfer material tends to be higher on the side on which the heated l-toner is placed and lower on the back side. This tendency is more noticeable when the transfer material is thick.Therefore, in the case of multiple copies or double-sided copying where copies are made on both sides, even if the conveyor belt I/configuration provides sufficient conveyance performance, In the case of composite copying in which copies are made multiple times on the same surface, the adhesion force between the toner image carrier and the transfer material exceeds the adhesion force between the belt and the transfer material. (Highly reliable transfer material) It becomes difficult to obtain general feeding and separation properties. In order to solve this situation, the above-mentioned method is used to correct the electrical resistance by heating the surface on which the toner is not placed before the transfer + O is conveyed to the heat fixing means. This is a function of composition. Note that the means for preheating is not necessarily limited to immediately after the transfer material is separated from the conveyor belt, but may also be used to heat the surface of the transfer material on which the 1-ner is not placed again after passing through the fixing means, or for electrophotography. Even if you heat the paper just before feeding it into the printer, the effect you get remains the same.

The transfer/first general feeding device according to the present invention has the above configuration. An electrophotographic printer using a semiconductor laser scanner in the optical system equipped with this device was used to
The following experiment was conducted in an environment with a temperature and humidity of 5% to confirm the effects of the present invention. That is, an electrophotographic printer to which this transfer/conveyance device is applied can be mounted on the transfer/conveyance device while the Δ4 size transfer) A is being fed horizontally. In this printer, the photoreceptor tram that serves as the I/ner image holder is a selenium/tellurium photoreceptor with a diameter of 150 m*, and the circumferential speed of the photoreceptor drum and transfer material conveyance speed at the conveyor belt l- are as described in 1-. 160+n/sec, the latent image on the photoreceptor is visualized using toner charged to the positive polarity using a reversal development method, and the high voltage DC power supply 13 is set to the negative polarity of 6.0, V
The image was transferred onto the transfer material 8 using the corona charger 12. After being separated from the conveyor belt I, the transfer material to which I. The temperature at a portion of this halogen lamp 15 is 200°C. Next, the transfer material is transferred to a heating roll fixing device 1 which serves as a fixing means.
9, where the toner is fixed on the surface of the transfer material.The heating roll of the fixing device and the linear pressure of the hack-up roll are 15 kg/cm, and the heating roll temperature is 80°C.
It is. The transfer material is A4 size, the direction of the fibers is perpendicular to the longitudinal direction of the transfer material, the weight is 130 g, and the moisture content is 9%. Printing I was carried out twice for 100 sheets, and the sheets were discharged using I-ray 20 and collected. At this time, defective separation of the transfer material from the tram 1 occurred for 78 sheets during the two-time L1 printing on one side. At this time, the transfer current flowing from the belt to the roller J was 63 tt A during the first printing, and 4 tt A during the second printing because the moisture in the transfer paper decreased during heat fixing and the resistance value increased.
It was 0μA. As a result of measuring the surface resistance of the transfer material that falls off after fixing during one-sided initial printing, it was found that the I.
X 1012Ω, the back side is 7X1011Ω, approximately 0
．． The resistance on the back of the 3 digits was low. Next, halogen lamp 1
5 was turned on and 100 sheets were printed twice on one side continuously in the same manner and collected on a paper discharge tray. At this time, there was no defective separation of the transfer paper from the drum. The transfer current to the drum was 35μA during the second printing, which was 5μ8 lower than when the halogen lamp was not lit (resulting in an increase in resistance). As a result of measuring the surface resistance of the transfer material after fixing, the surface resistance on which the I.ner was applied was 3.times.10@12 .OMEGA., and the surface resistance on the reverse side thereof was 9.times.10.sup.12 .OMEGA., which was the opposite value from the above-mentioned state.

Next, an experiment was conducted under the same experimental conditions as described in "-" by replacing the transfer material conveying belt. Volume resistivity is 5×101]Ω・
A transfer material conveying belt made of metal oxide-dispersed polyester resin with a thickness of 0.3 ++ m (cm) was made and the separation state of the transfer material was observed.As a result, there was no separation failure, but the transfer current was continuous (printing) and sometimes. This was not a desirable result in terms of the image, as it was observed that there was a decrease in the number of particles and transfer defects were observed. This phenomenon is presumed to be due to the fact that the time constant of the belt is approximately 10 seconds and that charge is accumulated during continuous printing. Next, the volume resistivity is 5X108Ω・cm and the thickness is 1. We created a transfer material conveyance belt made of carbon-dispersed polyurethane resin of Qmm.''1
As a result of observing the separation state of the transfer material C under the same conditions as described above, 68 sheets were obtained when the halogen lamp 15 was not turned on, and no defective transfer material separation occurred when the halogen lamp 15 was turned on. However, the charging current from the corona charger flows to the belt,
As a result, the transfer current decreased and transfer defects were observed. Therefore, although adding the heating means 14 was found to be effective in terms of the separation of the transfer material from the toner image carrier,
Considering the transferability, there is an appropriate range for the volume resistivity of the belt, which is estimated to be approximately 10 Kl to IQII Ω·cm.

Effects of the Invention According to the present invention, after the transfer material is separated from the transfer material conveying belt, the electric resistance value on the back side of the transfer material is equalized before being conveyed to the fixing means for fixing the toner on the transfer material. Therefore, when the paper is fed for the next multiple copies, the surface that comes into close contact with the conveyor belt has a high ability to retain electric charge, so the conveyor belt I and transfer A). The electrostatic adhesion force is always maintained high, the separation of the transfer material from the toner image carrier is highly reliable, and the conveyance of the transfer material is extremely stable. There is such a thing as a dog of value.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of an electrophotographic printer equipped with a transport device according to the present invention; FIGS. 2 and 3; FIG. Figures 4 and 5 are transfers using known electrostatic force)A
FIG. 1...Drum, 4...Developing section, 5...
...Transfer means, 8...Transfer material, 9...
Conveyor belt, 12...Corona charger for transfer, 13
．． 18...DC high voltage power supply, 14...Heating means, 15...Halogen lamp, 19...
...Heating roll fixing device. Name of agent Patent attorney Toshio Haka I Meijyo (-L#-guchi)

Claims (1)

[Claims] A means for supporting and stretching an endless transfer material conveying belt made of a conductor and rotating it in a fixed direction, and a means for sandwiching the transfer material between a toner image carrier and the transfer material conveying belt on the front side of the transfer material conveying belt. A transfer/conveyance system comprising at least a transfer means that has a corona charger on the back side to transfer a toner image onto a transfer material, and a means for separating the transfer material from a transfer material conveyance belt on the downstream side of the belt traveling side of the transfer means. The device is characterized by adding means for increasing the electrical resistance of the surface of the transfer material that was in contact with the conveyance belt after the transfer material is separated from the transfer material conveyance belt and before the toner on the transfer material is fixed. transfer/conveyance device.