JPS62191863A - Multiplex transfer device - Google Patents

Abstract

PURPOSE:To bring a color toner image to a multiplex transfer onto a transfer material by making the titled device satisfy at least two of conditions that the dielectric constant of a dielectric, a volume resistance, and thickness are set to the values of a prescribed range, and also, setting a critical surface tension to a prescribed value or below. CONSTITUTION:Polyester being a dielectric is wound and installed to a transfer drum 5, and in positions (a), (b) of the drum 5, the potential before and after the transfer time point at every transfer of each color toner is measured, and a transfer image is generated actually, and a measurement of the transfer efficiency is executed. As a result, by satisfying at least two conditions among the conditions that for instance, a dielectric constant, a volume resistance, and thickness are 3.0-13.0, 10<3>-10<16>OMEGAcm, and 70-200mum, respectively, and also, setting a critical surface tension to, for instance, 40dyn/cm or below, a color toner image can be brought to a multiple transfer satisfactorily onto a transfer image.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention carries a transfer material on an endlessly moving sheet-like transfer material carrier, and applies a transfer electric field to the transfer material on the transfer material carrier 1. It is a multi-pi transfer device that sequentially forms a plurality of color toner images on an image carrier and transfers them onto a transfer material to form a color image on the transfer material. The present invention relates to a multiplex ΦI,'Ij device that can be applied to image forming devices such as machines and color printers.

[Conventionally Senshi iki] Second [Ta wa iZ? FIG. 2 is an explanatory diagram of a color copying machine for printing a full-color image from a color original on a J: material. In the figure, there is a well-known corona around the photosensitive drum 1.1. Electrical appliances 2, Va optical optical system 3 developing device 4 transfer drum 5. A cleaning machine 6 is placed there. The optical system 3 includes a document scanning section 3a and a color separation filter 3b. -・The direction developing device 4 has four color developing devices around its center ←i4b, and the developing device 4Y is a yellow developing device;
M is magenta developer, 4C is cyan developer, and 4B
is a black developer. The developing device rotates as a whole to sequentially develop each of the four colors on the latent image formed on the photosensitive drum 1.

Further, the rolling tram 5 includes a drum structure including a sill 5a and a connecting part 5g, a transfer discharger 5b, a gripper 5c for grasping the leading edge of the transfer material 7, and an inner discharger 5d for market removal.
and an outer discharger 5e, between the peripheral surfaces of the L-shaped convex body 11
The area number is covered with a sheet-like transfer material carrier. 1st
The figure shows a perspective view of the transfer drum 5, and the transfer tram 5
The cylinders 5a on both sides of the cylinder 5a are connected by a connecting part 5g, and the connecting part 5g is provided with a gripper 5C for gripping the transfer material as shown in the figure.

A sheet-like dielectric material 5h, which is a carrier for the transfer material 1q, is used by being wound around the transfer drum 5 as shown. Further, a dielectric body 5h of the transfer drum 5 is provided on both frame portions of the transfer drum 5.
A cushioning material 5f of urethane rubber cap is wrapped around the photosensitive drum 1 to prevent it from coming into direct contact with the photosensitive drum 1.

With the above configuration, when the transfer of the four-color toner images sequentially formed on the photosensitive drum 1 onto the transfer material by the well-known color electrophotographic method is completed, the inner discharge device 5d and the outer discharge device 5e start discharging and transferring the toner images. After the material is neutralized, the transfer material is separated from the transfer drum 5 by a separating claw 8 and discharged onto a tray 10 via a mature roller fixing device 9.

In the above arrangement, it is effective to operate the transfer discharger 5b so as to transfer each color toner (repeatedly, by increasing the current applied to the transfer discharger 5b sequentially.The reason for this is is explained as follows.

First, a current 11 is applied during the first transfer.

This current charges the dielectric body 5h to Vl, and the toner on the photosensitive tram 1 is transferred to the transfer material. Since the transfer material is moving in synchronization with the photosensitive drum 1, the transfer material on the transfer drum 5F leaves the photosensitive tram after the transfer, but when it leaves the photosensitive drum 711, it removes the nearby air. That is, if the charge of the toner produced by the development of the two photosensitive drums 1 is, for example, negative (-) polarity, the photographic current becomes positive (+).

In this state, of the above-mentioned separated air, negatively charged air is deposited on the surface of the transfer material, and positively charged air is deposited on the photosensitive drum surface. And middle I: The negative I load attached to the photographic material is
This affects the positive charges generated during transfer on the back surface of the dielectric 5h, and acts to weaken the transfer electric field as a whole. At this time, since the transferred toner itself is also negative, the transfer electric field is weakened in the same way as the phenomenon described above. Therefore, it is necessary to increase the transfer current in order to compensate for the next transfer electric field.

The relationship between the transfer current and the charging potential of the dielectric material 5h is as follows: The transfer current of the second pass and the charging potential of the dielectric material are respectively I2. If V2, then II<I2. Vl<v2. Wood, IV2-V
It is preferable that ll be at least 0.5 KV or higher. A similar relationship holds true for subsequent transfer steps.

Further, the material of the dielectric 5h is Teflon.

Films such as polyester and triacetate-1 were used, but these dielectrics have a high saturation charge potential.
For this reason, if the potential after transfer becomes too high during transfer, a strong peeling discharge will occur when the transfer material and photosensitive drum l are separated, which will disturb the toner image on the transfer material due to transfer and cause IN. .

In order to solve this problem, in an electrophotographic color copying machine, it is preferable to set the potential after finishing the 11 colors to about 3 KV.

However, if the saturation charging potential of the F- dielectric is high, it is necessary to finely control the transfer current in order to satisfy the above condition 6 (lV2-Vl l>0.5KV). Also, it saturates with a small current.;1? In order to reach the electric potential, it is necessary to reduce the current during transfer of 'J'S 1 color', which makes the corona discharge unstable, resulting in poor transfer. There was a problem.

- After the transfer of each color toner to the transfer material is completed and the transfer material is separated from the transfer drum 5, the dielectric body consists of a fur brush etc. placed at an appropriate position on the circumference of the transfer drum 1-. Some items need to be cleaned using a cleaning device. The reason for this is that the image is generally transferred to the entire surface of the transfer material supported by the dielectric 5h of the transfer drum 5, except for the portion gripped by the gripper at the tip. For this purpose, a photosensitive drum is used.
The developed images formed on the second transfer material form a wider image than the transfer image formed on the transfer material. Therefore, all the toner images on the outside of the transfer material are transferred to the dielectric material 5h, and when a transfer material larger than the previous paper size is applied after 1, the toner image on the outside of the transfer material becomes a stain on the back of the transfer material. This caused a drop in quality.

Therefore, it is necessary to completely clean the residual toner on the dielectric surface between the end of the previous transfer process and the start of the next transfer process. However, the conventionally used dielectric 5
Films made of polyester, triacetate, or the like have a problem in that it is difficult to clean the residual toner charged on the film between the sheets. For this reason, in commonly used cleaning devices such as the fur brush method, it is necessary to increase the rotation speed of the fur plan and increase the thickness of the thread in order to increase the contact pressure after the brush, making the device very complicated. It had no choice but to become larger.

[Problem that the invention seeks to solve]

The present invention solves the above-mentioned problems that occur when a dielectric material is used as a transfer material carrier in a multi-transfer device and the electric field for transfer is increased for each transfer.

[Configuration to solve the problem]

The multiple transfer 'A' position of the present invention that achieves the above object is a device that sequentially performs multiple transfer onto a color toner image transfer material that is primarily formed on an image bearing member, and the transfer material is held in L of the device. a dielectric member for transporting and guiding the transfer material to the transfer position of the image carrier; a dielectric support means for supporting the dielectric member; The transfer discharge means is provided with a transfer discharge means that sequentially increases current or voltage for each color, and the dielectric has a dielectric constant of 3.0 to 13, o, and a volume resistivity. is 1
0'l~1016Ω*cm.

The thickness satisfies at least two of the conditions of 70 to 200 gm, and the critical surface tension is 40 d y
Use materials of n/cm or less. .

In addition, dielectric material is used for each color in the lower stage of the transfer discharge as described in 1-.
The outer cleaning means of the cleaning stage F, which is made of polyvinylidene fluoride (PVdF) and is provided facing the dielectric, uses a fur brush.

〔Example〕

Regarding the dielectric material 5h of the multiple transfer device according to the present invention, what about the dielectric material? iF electrical properties and dielectric constant depending on thickness.

The results of investigating the relationship between volume resistivity will be explained below.

FIG. 6 shows the results of measurements made with polyester (hereinafter referred to as PET) films used as dielectrics and with different thicknesses in order to examine the relationship between dielectric constant and charging potential.

PET as an absorbent was wound around the transfer drum 5, and the voltage was set at positions a and b of the transfer drum 5 shown in FIG. A transferred image was actually created and the transfer effectiveness; ↑l was measured. These 7Il11 fixed points a and b indicate the positions immediately before and after the charging area of the transfer charger, respectively.

It represents the potential at each measurement point a, b.

The subscripts of measurement points a and b indicate the rotation speed of the transfer drum. The transfer conditions were determined as follows. The moving speed of the dielectric was approximately 160 mm/sec, the opening width of the transfer (IP appliance) was 22 mm, and the distance between the discharge wire and the photosensitive drum was approximately 11 mm.
As mm 1 color 11 transfer 200 river A (6,3KV)
, 2 colors rj 300 gA (7,3KV) , 3
Color 400, A (8, IKV), 4 colors 1] 500. A
(8,8KV), sequentially under the conditions of B)/? iF'
It shows the potential when it is set. Note that the numbers in parentheses indicate the voltage applied to the charger. The time between repeated charging of the comb is about 3 seconds each time, and the temperature and humidity environment is 20° C. and 60%.

FIG. 7 shows the transfer rate of multiple transfer under the transfer conditions shown in FIG. 6 described above. The multiple transfer efficiency is 80
If the ratio is divided by %, phenomena such as unevenness in both images occur, and the image quality is significantly impaired.

In order to explain FIG. 6, the equation 1q regarding the 5th episode capacity jη will be used.

Dielectric capacity 1. VC is j1? Electric charge:,f Between Q and 4iF electric potential V, there is a relationship of Q=CV or V-17/C.

−・Fang, Shizuka′・[Yong! 1i: C is C=εS/d (ε
: Dielectric constant.

S2 Determined by the area of the dielectric, d: thickness of the dielectric,
The charged potential (2) of the dielectric is expressed as V=Qd/εS.

Now, PET is used as the dielectric material, and only the thickness is changed (i.e., the dielectric constant ε, I[? The heavy charge Q is the same), so the charged potential after transfer is v200lm/V100gm=2,V
The relationship was 100 μm/V50gm=2, and such charging was actually observed. As can be seen from Figures 6 and 7, when the charged potential after transfer becomes 3KV or more, the multiple transfer efficiency decreases significantly. It was done.

From the above results, it can be seen that there are two methods for suppressing the charging potential to about 3 KV after transfer without changing the charging conditions during transfer.

The first method is to change the thickness of the dielectric (e.g. PE
In the case of T, it is about 50ILm). Another method is to change the permittivity of the dielectric (for example, PET (7LiA electric constant is εPET=3.2t').
For a dielectric with Jε=12, the thickness is about 200 lm and 5
Charger equivalent to 0gm thick PET (gr can be obtained).

Now, examining the problems in the method of changing the thickness of the dielectric material, the dielectric material is used by being wound around a transfer drum as shown in FIG. Since the only places that support this dielectric are the cylinders 5a on both sides and the connecting part 5g, it depends on the strength of the dielectric, but in the case of PET, B4
When trying to support a transfer material of the size (JIS standard), if it is less than 70 gm, unevenness will easily occur and the transfer will be difficult.
Q-material and dielectric: V-body become difficult to adhere to. Since an air layer exists between the two in such a portion where they do not come into close contact with each other, the dielectric constant of this portion decreases, and as a result, the band-shaped potential increases after transfer, resulting in transfer failure and deterioration of image quality.

On the other hand, the 1 conductivity of the dielectric cannot be easily changed because it is the same value as that of the resin constituting the dielectric.

Therefore, it is necessary to select from among various dielectric materials 1.

Regarding the charging current used in the above explanation, it is important to use a corona discharge current under stable conditions, and to use the nth
Condition 1: The difference between the color and the n+1th color must be north of 0.5 KV 1 Furthermore, due to conditions such as leak prevention, the first color is l OO#LA ~ 200 tiles A, and the second color is 200 tiles A ~
It is safe to use 300 A, the third color is 3008 LA to 400 LA, and the fourth color is 400 LA to 500 JLA.

The shaded area in Fig. 8 indicates the dielectric 41? including these conditions.
It shows the practical range in which good multiple transfer can be performed with respect to the dielectric constant and thickness of the dielectric scattering material so that the electric potential does not exceed the aforementioned 3 KV.

Volume resistivity is directly related to the ability to retain a charged charge, so changes in the temperature and humidity environment may reduce the adsorption force of the transfer material to the dielectric, causing the transfer material to separate from the transfer drum. Dispersing carbon powder in PVC to reduce volume resistance to 1
When the conveyance characteristics were investigated for those having a resistance of 08 Ωem to 1016 Ωcm, stable conveyance characteristics were shown in the shaded area A in FIG.

- For the transfer current condition, 1 color 11 is 200. A.

The second color 1-1 is 300 ru A, the third color is 400 tile A, and the fourth color [1 is 500 ru A, and the test environment is a temperature of 30″0.
, 7FiA degree is 80%. At this time, conditions in which the multiple transfer efficiency is stable at 80% or more for yellow, magenta, cyan, and black are shown in the shaded area B in the figure.

That is, the claws in areas A and B in the figure indicate the practical range. Considering changes in usage conditions such as temperature and humidity environment, ease of mounting, etc., the preferred range of volume resistance is 1Q10 ~
1Q15Ωcm, and the thickness at this time is loo8Lm~2
Approximately 00 μm is good.

Based on the above results, the charging characteristics of the resins that have been put into practical use were investigated, and the results shown in FIG. 4 were obtained. FIG. 5 shows an investigation of multiple transfer efficiency. Note that a and b on the horizontal axis in FIG. 4 correspond to Jllll fixed points a and b in FIG. 6 above. FIG. 5 shows the results of measuring the transfer efficiency -V of each color toner for each existing resin film.

As is clear from these experimental results, polyvinylidene fluoride resin (hereinafter referred to as PV
dF) has a dielectric constant of ε=12.0 and a volume resistance of 1014
The best sheet 1t was found in terms of Ω*cm (conveyance characteristics), ease of winding around a transfer drum, and multiple transfer characteristics even at a thickness of 200 mm.

Furthermore, it has been found that PVdF is extremely superior to other resin films in terms of the cleaning properties after multiple transfer described below, and the reasons for this will be discussed below.

As mentioned above, in order to remove the residual toner adhering to the surface of the substrate after multiple transfer is completed, it is preferable to rub the surface with a cleaning means such as a fur brush. Toner, which is a charged particle, is strongly electrically adsorbed to the dielectric material, and toner using polyester or styrene resin has high surface energy, so the surface of the dielectric material itself By using a toner with low energy, toner cleaning can be facilitated.

Using the multi-transfer device shown in Figure 2, we transferred the toner image directly onto the dielectric film without supplying any transfer material, and then operated a fur brush cleaning device to examine the cleaning characteristics. It looked like Table 2.

In Table 2, the mark X in the table indicates that the cleaning during one rotation of the transfer drum was poor, and the next multiple transfer would cause the history of the transfer material to be distorted. The mark Δ indicates that the above-mentioned 'Af5 scratch did not occur but the cleaning was insufficient, and the mark O indicates that the toner on the dielectric was completely removed.

In addition, the critical surface tension in the table is a physical property that is related to the magnitude of surface energy; the smaller the surface energy, the smaller the critical surface tension.

By the way, the above-mentioned cleaning device is, in detail, a fur brush 5j equipped with a suction device using back pressure; tA? ff
It is composed of brushes 51 facing each other with a body film in between. This brush 51 has a good pressing effect so that the dielectric material is not deformed by the contact pressure when the fur brush 5j is brought into contact with the 7A heavy body, and a rotating roller may be used in place of the fur brush.

On the other hand, the fur brush 5j has a diameter of 28 mm.

The brush bristles were made of rayon yarn planted at 14,400 filaments/inch2, and the rotation speed was set at 300 rpm. To further increase cleaning efficiency,
It is effective to lower the electrical resistance by replacing the rayon thread with carbon thread, or to reduce the number of rotations of the brush to L, or to use both in combination.

From the above-mentioned examination of the cleaning properties, it has been found that when using a toner made of wood 11ti as described above, it is preferable to have a surface energy of 40 dyn/cm or less.

[Other Examples]

In addition, a tram-shaped electronic photograph 3' was taken as a leave for I-Star Image 4tj.
(The hfx body is shown as an example, but other shapes include a belt shape, and latent image forming methods include a tI-shaped electrode on the latent image body.
It is also possible to form 84 images by the r-ono JAε system jIa system. On the other hand, in addition to the transfer drum, the present invention is also effective for a heald system that moves endlessly.

Furthermore, polyvinylidene fluoride resin (PVd) is used as a dielectric material.
F) is preferred, but this is an example of resins that meet the conditions of the present invention among the resins that Inventor Nagisa recognized as existing. or mesh-like ones are effective.

〔Effect of the invention〕

(1) Obtaining good transfer characteristics by using a dielectric material having the conditions described in the above-mentioned multi-ton transfer device as a transfer material support member and performing multi-copy transfer using a corona beam.
It has become possible to achieve even more cleaning effects by using a cleaning device.

[Brief explanation of drawings]

Fig. 1 is a perspective view of a transfer drum which is an embodiment of the transfer material support means of a 3-multiple transfer device to which the present invention is applied, and Fig. 2 is a perspective view of a transfer drum which is an embodiment of the multi-transfer device to which an electrophotographic method is applied. 3 is an explanatory diagram of a method for determining the charging potential of a dielectric material provided on a transfer drum; FIG. 4 is a graph illustrating the charging characteristics of various dielectric materials;
The figure is: Shown in Figure 54? ! Figure 6 is a graph showing the relationship between the difference in the thickness of PET film and charging characteristics. Figure 7 is a graph showing the multiple transfer efficiency when multiple transfer is performed using the charging characteristics shown in Figure 6. Graph showing transfer efficiency,
FIG. 8 is a graph showing dielectric constant, dielectric thickness, and multi-transferability, and FIG. 9 is a graph showing volume resistance, dielectric thickness, transfer material conveyance 11r property, and multi-ton transfer property. In the figure, ■ is image 41! 4 is a developing device, 5 is a transfer drum, 5b is for transfer; j; 2 electric appliances;
5h is a resin film with an M shape. 6 is a developing device, A is an area showing stable conveyance characteristics, B is an area showing good multiple transfer characteristics, Y is yellow, M is magenta, C is cyan, B K ! i indicates black.

Claims (3)

[Claims] (1) A device that sequentially multiple-transfers color toner images sequentially formed on an image carrier onto a transfer material, holds the transfer material thereon, and transports and guides the transfer material to a transfer position on the image carrier. a dielectric for supporting the dielectric, a dielectric support means for supporting the dielectric,
A multi-transfer device is provided with a transfer discharge means disposed through the dielectric with respect to the image carrier at the transfer position, and the transfer discharge means sequentially increases current or voltage for each color. The body has a dielectric constant of 3.0 to 13.0, a volume resistivity of 10^9 to 10^1^6 Ω・cm, and a thickness of 70 to 200.
A multi-transfer device, characterized in that it satisfies at least two of the conditions of μm, and further has a critical surface tension of 40 dyn/cm or less. (2) The above dielectric material is polyvinylidene fluoride resin (PVd
F) Claim No. 1 characterized in that it is a film (
The multiple transfer device according to item 1). (3) A device that sequentially multiple-transfers color toner images sequentially formed on an image carrier onto a transfer material, holding the transfer material thereon and transporting and guiding the transfer material to a transfer position on the image carrier. a dielectric for supporting the dielectric, a dielectric support means for supporting the dielectric,
A multi-transfer device is provided with a transfer discharge means disposed through the dielectric with respect to the image carrier at the transfer position, and the transfer discharge means sequentially increases current or voltage for each color. A multiple transfer device characterized in that the dielectric is made of polyvinylidene fluoride (PVdF) resin, and the outer cleaning means of the cleaning means provided facing the dielectric is a fur brush.