JPH02156271A - Electrostatic conveying and transferring device - Google Patents

Abstract

PURPOSE:To restrain the occurrence of the pattern of electrode by alternately supplying high voltage and low voltage to an electrode which is moved to a paper conveying position by a power supply means for attracting paper. CONSTITUTION:Electric field is generated between the group of the electrodes 66 connected to a positive part and an earth part, so that the paper can be attracted. When the paper 50 is fed by a feeding roller 46 in such a state, the paper 50, from its leading edge, is sequentially attracted to a transfer drum 42 at a part where it abuts on the transfer drum 42 and the attracted paper is fed to the transferring position with the rotation of the transfer drum 42, and the toner image of a 1st color is transferred on the paper. At this time, the potential is changed by repeating positive, floating, earth, floating and positive in the electrode 66, so that a state where charge is injected in the specified position of the paper is not kept until reaching the transferring position. Thus, the occurrence of the pattern of electrode is restrained.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electrostatic transport transfer device used in an image forming apparatus such as an electrophotographic copying machine.

2. Description of the Related Art In image forming apparatuses such as electrophotographic copying machines, an image carrier (
Represented by a photoreceptor. ) A common method for transferring the toner image formed on a transfer material (typically paper) is to transport the paper over the toner image and simultaneously charge the paper from the back side to electrostatically attract the toner. It is true. especially,
The transfer method, in which the paper is once supported on a transfer drum that is driven to rotate in synchronization with the photoreceptor, is mainly used in color copying machines because it enables multiple transfers to the paper. .

There are two ways to support the paper on the transfer drum: mechanical gripping mechanisms such as grippers, and electrostatic adsorption. Since the paper can be supported, it is possible to narrow the paper interval regardless of the size of the paper in the longitudinal direction, which has the advantage of increasing the copying speed accordingly.

FIG. 13 is a view showing a conventional electrostatic transfer transfer device that embodies a method of supporting paper on a transfer drum by electrostatic adsorption. 2 is a photoreceptor, which sends a toner image T obtained by being developed by a developing device (not shown) to a transfer position. 4
is a transfer drum that is rotatably supported so as to contact or be close to the surface of the photoreceptor 2 through the paper at the transfer position. As shown in FIG. 14 and FIG. 15, respectively, a resin film 6 formed in an endless shape and a plurality of electrodes 3a formed alternately at regular intervals inside the resin film 6.
, 3b and these electrodes 3a.

8b to the resin film 6, and a support 10 made of an insulator. Note that the width of the support body 10 is made smaller than the width of the resin film 6, so that the electrodes 3a, 3
b are alternately exposed inside the resin film 6, so that each brush can receive power from a different power supply brush. Transfer brushes 12a and 12b are provided inside the transfer drum 4 for transferring and adsorbing paper.
And suction brushes 14a, 14b, 16a, 16b are fixed.

FIG. 16 is a power supply connection diagram of each brush. Transfer brushes 12a and 1 that slide on the electrodes 8a and gb at the transfer position
2b is connected to the positive side of the power supply 18 via the switch 20, and the negative side of the power supply 18 is grounded. A suction brush 14a slides on the electrode 8a at a paper transport position other than the transfer position.

A suction brush 14b 16a is grounded and also slides on the electrode 8b at the paper conveyance position.

16b are each connected to the positive side of the power supply 22.26 via a switch 24.28, and the negative side of the power supply 22.26 is grounded.

The operation of the electrostatic transfer transfer device having the above configuration will be explained.

The paper 32 placed on the paper feed tray 30 is sent out at a predetermined timing by the rotation of a feed roller 34 that is pivotally supported so as to come into contact with the upper surface of the paper 32. When the leading edge of the paper reaches the vicinity of the transfer drum 4, the switch 24 is turned on, and the output voltage of the power supply 22 is applied to every other electrode 8b via the electrode 14b, and the electric field generated between the electrodes 3a and 3b causes the paper to The resin film 6 and the resin film 6 are charged with different polarities and come to exert an attractive force to each other. When the paper supported on the surface of the transfer drum 4 reaches the vicinity of the transfer area in synchronization with the rotation of the transfer drum 4, the switch 20 is turned on and the electrode 3a is turned on.
, 3b, a DC voltage is applied to both of them, and the paper forms a toner image T.
Transfer is performed by electrostatically attracting the toner image T on the photoreceptor 2, which is charged to the opposite polarity and rotates at the same peripheral speed as the paper. At this time, a DC voltage is applied to the suction brushes 14b and 16b located downstream of the transfer brush 12b, and if this copy is a full color copy, the first
The paper that has undergone color transfer is continuously supported on the transfer drum. Transfers using the second and third colors are performed in the same manner, and when three or four transfers are completed, the switch 28 is turned off, and the paper is peeled off from the transfer drum 4 by the peeling claw 36 and placed on the conveyor belt 38. Sent out. In the case of monochrome copying, the switch 28 is always turned off, and the paper is ejected every time - times of transfer are completed.

Problems to be Solved by the Invention When an electrostatic transfer transfer device having the configuration shown in FIGS. 13 to 16 is used, the following problems occur.

That is, in the conventional configuration described above, since the plurality of electrodes 3a and 3b are always at the same potential when paper is being transported, the charges injected into the portions of the sheet being transported that correspond to the electrodes and the portions that are not connected to the electrodes are different. Moreover, since the paper has a relatively high resistance, this difference in injected charge is carried over to the transfer position, and therefore, the transfer efficiency differs depending on the difference in injected charge, resulting in a difference in the transferred image. High concentration areas and low concentration areas occur alternately depending on the pitch of the electrodes.

This phenomenon (hereinafter referred to as electrode pattern) is noticeable in high-resistance paper such as low water content paper.

Therefore, an object of the present invention is to provide an electrostatic transfer transfer device that can suppress or prevent electrode patterns.

On the other hand, in this type of electrostatic transfer transfer device, if there are defects such as minute protrusions on the surface of the photoreceptor or the surface of the resin film,
There is a problem in that discharge occurs between the photoreceptor and the transfer drum through the defective portion, resulting in damage to the photoreceptor or the resin film. In particular, there is a risk of ignition if the resin film is flammable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an electrostatic transfer transfer device capable of preventing damage to a photoreceptor and a resin film due to discharge.

Means for Solving the Problems The above-mentioned technical problems are solved by an electrostatic transfer transfer device having the following configurations (1) and (2).

(1) A semiconductive resin film that moves while keeping the paper to which the toner image of the photoconductor is transferred in close contact with the outer surface at least at the transfer position, and a plurality of electrodes arranged in parallel at regular intervals inside this resin film. and a transfer power supply means that contacts the electrode that has moved to the transfer position among the electrodes and supplies a voltage with a polarity opposite to the scratchability of the toner; , and a paper adsorption power supply means that alternately supplies high and low voltages to form an electrostatic transfer transfer device.

(2) In the configuration of (1), the volume resistivity of the resin film is 106 Ω·cm to 10'2 Ω·CIn.

Here, high voltage and low voltage mean a relatively + (plus) side voltage and a relatively - (minus) side voltage. Therefore, specific combinations of high voltage and low voltage include +2000V and +500V, +1500V and OV, +1000V and -500V, and OV and -1500V.
, -500V and -2000V.

According to the configuration of operation (1), the paper adsorption power supply means alternately supplies high voltage and low voltage to the electrode moved to the paper transport position, so that the paper that comes into contact with the resin film is
It is adsorbed onto the resin film by the electric field formed between the electrode group to which a high voltage is supplied and the electrode group to which a low voltage is supplied.
It is transported according to the movement of the resin film. At this time, looking at the potential of each electrode, as the resin film moves, high voltage application and low voltage application are repeated alternately, so the electrodes are not always at the same potential, and the injected charge is Generation of electrode patterns caused by being carried over to the transfer position is suppressed.

According to configuration (2), the volume resistivity of the resin film is 1012
Since it is smaller than Ωcm, there is less difference in the charge injected into the paper moved to the transfer position through the resin film between the part corresponding to the electrode and the part not corresponding to the electrode. The transfer electric field becomes uniform between the areas where the electrode is applied and the area where it is not, and the generation of electrode patterns can be prevented. In addition, the volume resistivity of the resin film was set to 10' Ω・c
Since it is set larger than m, even if a discharge occurs between the photoreceptor and the resin film at the transfer position, the discharge current will not be continued due to the discharge current limiting ability.
There is no risk of damage to the resin film or photoreceptor. In other words, when the volume resistivity is relatively small, the discharge continues when it starts through a defect such as a protrusion, whereas when the volume resistivity is relatively large, the discharge continues. Even if the discharge starts, it will stop early due to the voltage drop across the high resistance resin film.

Example Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a partially cutaway side view of an electrostatic transfer transfer device to which the present invention can be applied, FIG. 2 is an enlarged view of the broken part in FIG. 1, and FIG. 3 is along the line ■-■ in FIG. 4 is a partial perspective view of the transfer drum shown in FIG. 1;

In FIG. 1, reference numeral 40 indicates an electrostatic latent image formed on the surface of the photoreceptor 40, which is developed in black and white or color by a developing device (not shown); A transfer drum is arranged so as to be in contact with the transfer drum; 44 is a brush power supply device for supplying power to the electrodes of the transfer drum 42;
46 is a feed roller that feeds the paper 50 placed on the paper feed tray 48 in the direction of the transfer drum 42; 52 is a peeling claw whose tip is movable toward and away from the transfer drum 42 at the peeling position; 54; is a conveyor belt that conveys the paper peeled off by the peeling claw 52 toward a fixing device that does not face the sheet.

As shown in FIG. 4, the transfer drum 42 includes a rigid drum 62 made of metal or the like, an insulating support 64 provided on the outer periphery of the rigid drum 62, and a plurality of drums provided on the support 64 at regular intervals. It consists of a strip-shaped electrode 66 and a semiconductive resin film 68 that is tightly attached to the support 64 and the electrode 66 so that the vicinity of the end of the electrode 66 is exposed. Here, the semiconductive resin film 68 is made of a resin such as acrylic, vinyl chloride, polyester, polypropylene, or various rubber containing an appropriate amount of an antistatic agent such as carbon black, and has a volume resistivity of 106 to 10'20. - cm, and its thickness is, for example, 0.25 mm. The electrode 66 can also be formed on the support 64 by conventional conductive patterning techniques such as etching, screen printing, etc., and has a width of about 0.5 m. For example, as shown in FIG. 5, a support 64 made of polyester and having a thickness of 50 μm
If a Cu electrode 66a with a thickness of 35 .mu.m is formed on the surface of the Cu electrode 66a by etching, and an N1 electrode 66b with a thickness of 2 to 3 .mu.m is formed on the surface of the Cu electrode 66a for the purpose of preventing oxidation and improving wear resistance, it can be used for a long period of time. A transfer drum can be provided.

Regarding the spacing between each electrode, if it is 1 mm or more, electrode patterns are likely to occur, so the smaller the spacing, the better; however, if it is too small, secondary problems such as short circuits will occur, so the spacing should be about 0.
5 is optimal. The support body 64 has a hardness (JIS K6
301) is made of an elastic material whose angle is 50° or less, or by interposing a homogeneous elastic material layer (not shown) between the support 64 and the rigid drum 62, the contact force between the transfer drum and the photoreceptor is stabilized. 1, it becomes possible to stabilize the transfer efficiency, etc. In FIG. 4, the vicinity of the end of the electrode 66 is exposed because power is supplied to one side of the transfer drum 42 by a brush power supply device to be described below.

As shown in FIG. 3, the brush power supply device 44 is provided to cover the exposed electrode portion of the transfer drum 42, and inside the brush power supply device 44, two brushes for power supply for performing various functions are arranged in the circumferential direction. arranged in alternating rows. Brush power supply device 44
have different functions depending on their positions in the circumferential direction, and as shown in FIG. and a second Wi feeding section 443 inserted upstream of the peeling position. Since the arrangement of the brushes in the transfer section 441, the first conveyance section 442, and the second conveyance section 443 is the same, the configuration of the first conveyance section 442 will be explained with reference to FIG. Note that this figure shows a cross section corresponding to one row of brushes arranged in two rows. A plurality of recesses 56a are formed inside the housing 56 at regular intervals in the circumferential direction, and inside the recesses 56a,
A first suction brush 78 made of a base body 78a and conductive fibers 78b is housed. The first suction brush 78 can be connected to an external circuit via the metal plate 58 and the connection terminal 60 provided at the bottom of the base 78a. The height al at which the first suction brush 78 projects from the inner surface of the housing 56 is, for example, 1.5 to 2.0 mm, and the length a2 at which the brush bites into the electrode forming surface EL of the transfer drum.
is approximately 1 stop, for example. As described above, in this embodiment, each brush is accommodated in the recess 56a of the housing 56, so that the conductive fibers 78b are prevented from spreading or falling down.

The power connection of each part of the brush power supply device will be explained with reference to FIG. In addition, in the figure, the brush power supply device 44 is connected to the first conveyance section 44.
This corresponds to a developed plan view cut away between the second and second conveyance sections 443 (section A in FIG. 1). In the transfer section 441, 70 is a transfer brush, which is connected to the positive side of a transfer power source 74 via a switch 72.
The negative side of 4 is grounded. According to this configuration, a voltage having a polarity opposite to that of the toner can be supplied to the electrode that has moved to the transfer position as the transfer drum rotates.

Auxiliary transfer brushes 76 are provided on both sides of the transfer brush 70, and by grounding these, the electric field in the transfer section can be stabilized and good transfer quality can be obtained. can. That is, since transfer is generally performed by the charged toner particles on the photoreceptor moving along the lines of electric force that form the transfer electric field, by providing an auxiliary transfer brush, the transfer electric field is confined in a narrow space. It is possible to prevent the toner particles from being transferred before they move to the transfer position, and defects such as blurring of the transferred image are less likely to occur. In the first conveyance section 442, the first suction brushes 78 are alternately connected to the switch 80 and the ground section. 82 is a first suction power source provided between the switch 80 and the ground portion. In the second conveyance section 443, 8
Reference numeral 4 designates second suction brushes, which are alternately connected to the changeover switch 86 and the ground portion. Changeover switch 8
6 switches the connection of the second suction power source 88, whose negative side is grounded, between the connection to the positive side and the connection to the ground portion.

Conventionally, brush power was supplied from the inside of the transfer drum, which made the wiring connections described above extremely complicated.However, if the brush power is supplied from the outside of the transfer drum as in this example, maintenance becomes easier. In addition to improving the performance, the degree of freedom in wiring also increases. Furthermore, since the brush power supply device is provided on one side of the transfer drum, the device can be made compact.

Furthermore, compared to the case where the brush power supply device is divided into both sides of the transfer drum, it is not necessary to take much time to adjust the pitch between the brushes.

The operation of the apparatus of this embodiment will be explained below. Transfer drum 4
2 is rotated and the switch 80 is turned on, as the transfer drum 42 rotates, the electrode 66 corresponding to the first conveying section 442 changes to positive, floating, ground, floating, floating, etc. as shown in FIG. Since the potential changes repeatedly in the positive, .

The period during which the electrode is floating is provided to prevent a short circuit between the positive part and the ground part of the brush via the same electrode. An electric field is formed between the electrode group connected to the positive part and the ground part, making it possible to attract paper. When the paper 50 is sent out by the feed roller 46 in this state, this paper is transferred to the transfer drum 42.
The transfer drum 42 is successively attracted to the transfer drum 42 starting from the tip at the contact portion with the transfer drum 42 . The paper adsorbed onto the transfer drum 42 is sent to the transfer position as the transfer drum 42 rotates, where it is transferred to the first transfer position.
A colored toner image is transferred. At this time, since the state in which charges are injected into a specific position of the paper at the paper transport position is not maintained until the transfer position, electrode patterns are less likely to occur. The paper onto which the first color toner image has been transferred is adsorbed by the transfer drum 42 as it is, and then rotates two or three more times to transfer the second and subsequent color toner images. For transfer of toner images of the second and subsequent colors, the second conveyance section 443 is also in a paper adsorption state, similar to the East 1 Manchuria 442. When the transfer of all the toner images is completed, the switch 86 is switched to the ground side at a timing earlier than the leading edge of the paper reaches the peeling position by a predetermined time, and the suction force in the second conveying section 443 is gradually removed. The paper is peeled off from the transfer drum 32 by a peeling claw 52 and sent to the next process such as a fixing device by a conveyor belt 54. Here, the reason why the second conveying section 443 is grounded at the above timing is due to the extrusion that occurs when the paper is forcibly peeled off by the peeling claw 52 before the static elimination of the resin film is completed with an appropriate time constant. This is to prevent the phenomenon of toner scattering.

The optimal range of the volume resistivity of the resin film will be described below. Figure 8 shows the spark generation rate due to discharge and the electrode electrode when resin films with various volume resistivities were prepared and the volume resistivities were measured using the measurement method described later. Pattern occurrence degree and volume resistivity ρ7
It is a graph showing the relationship between In the same figure, the horizontal axis is the volume resistivity, the vertical axis is the spark generation pattern and the degree of electrode pattern generation, and the curves shown by solid lines and broken lines correspond to the electrode pattern generation degree and the spark generation rate, respectively. Incidentally, in order to change the volume resistivity, the content of an antistatic agent such as carbon black contained in the resin film may be changed. Regarding the spark generation rate, the volume resistivity of the resin film is 10
If it is larger than 6 Ω・cm, it is 0 (%), and this tendency is 105 to 106 V/cm (10 to 100 V
/μm) (The results were almost the same in the transfer electric field f'L using DAt.The reason why the spark generation rate is 0 at such a relatively high volume resistivity is due to the discharge between the photoreceptor and the transfer drum. This is thought to be because even if the discharge starts, it will stop instantaneously due to the voltage drop across the high-resistance resin film.On the other hand, the degree of electrode pattern generation is 10
It has been found that at a commonly used transfer electric field of 5 to 10'V/am, the volume resistivity of the resin film gradually increases as it becomes larger than 10'20.am. With the configuration of the present invention (1), even though the state in which electric charges are injected into a specific position of the paper at the paper transport position is not maintained until the transfer position, such an electrode pattern may occur. This is thought to be because when the volume resistivity of the resin film is large, the magnitude of the transfer electric field formed at the transfer position differs between the portion corresponding to the electrode and the portion not corresponding to the electrode. In order to eliminate the non-uniformity of the transfer electric field due to the presence or absence of electrodes, it is effective to reduce the distance between the electrodes. Therefore, if the spacing is made smaller than 0 and 5 in this example, the critical value (10" Ω cm) will also be different, and the resistivity will be larger than 1012 Ω Cl11. However, due to problems with electrode manufacturing technology such as screen printing or secondary problems such as short circuits, the spacing between the electrodes may not be reduced to 0.
．． Since it is difficult to make the thickness smaller than 5 mm, the above-mentioned critical value can be said to be effective and appropriate in preventing the occurrence of electrode patterns. Based on the above results, the volume resistivity of the resin film is 106 Ω・cm to 10
By wiping within the range of '2 Ω·cm, damage to the resin film or photoreceptor due to discharge can be prevented, and generation of electrode patterns on the transferred image can be prevented.

Incidentally, depending on the material, the volume resistivity of a semiconductive resin film does not necessarily remain constant when the applied electric field is changed. That is, as shown in Fig. 9, there is material A in which the measured volume resistivity is almost constant regardless of the electric field applied to the resin film, and there is also material A in which the measured volume resistivity is almost constant regardless of the electric field applied to the resin film. There is also a material B that changes significantly depending on the situation. For this reason, the volume resistivity of the resin film is set to 10" to 1012
The question is what kind of electric field should be set in the range of Ω·cm. In other words, in what range is the electric field applied to the resin film, the transfer electric field (10S~
It is necessary to clarify whether 10' V/am) is applied, and by clarifying this, the electric field to be applied when measuring the volume resistivity of the resin film becomes clear.

FIG. 10 is a diagram showing a transcription model. Electrode and some light I
Between the bases of the book, there are seven trees with a conductivity of 1ε3 and a thickness of d, a sheet of paper with a conductivity of 1ε3 and a thickness of d, a gap with a conductivity of 51 and a thickness of CLa, and a gap with a transmittance of 1. A toner l with a dielectric constant of 5 and a thickness d and a photosensitive layer of a photoconductor with a dielectric constant of 5 and a thickness d are bonded in this order, and a transfer power source is connected between the electrode and the base of the photoconductor so that the electrode side is 0. A model with V applied is shown. At this time, if the surface potential of the toner layer after development is V, then
The transfer electric field (electric field applied to the gap) E6 is ε$ εP ea εt
ε, and the electric field E within the resin film is 8 m! P ga εt
becomes ε. Therefore, from equations (1) and (2), E,
/E, =ε, /ε, ...(3). Here, since ε can be set as 1, from equation (3), Es = Ea /ε, (4) can be obtained. Since E is a practical transfer electric field, 10' (
V/cm) <E, < l O' (V/cm)
=45). Therefore, from equations (4) and (5), 10
5/εs (V/am><Es<10
' / εs (V/cm) - (6). Therefore, for example, if the dielectric constant ε of the resin film is 10, then 10' (V/cm) <Es <10' (V
/am) (7), and for materials with ε = 10, the volume resistivity measured by applying an applied electric field within the range of equation (7) is the target. After all, in this specification, the volume resistivity of the resin film is 10'' to 10'2 Ω·mark, which means that when the permittivity is ε, 10'
The volume resistivity of the resin film measured at an arbitrary electric field strength of /εs to 10'/ls (V/cm) is in the range of 101 to 1012 Ω·Ca.

Specifically, if ε,=10, even if 104 to 10
Even if the volume resistivity measured by wiping an applied electric field in a range other than 'V/cm is not within 10@~1012Ω・cll, even if there is a part of the volume resistivity-electric field curve in the region shown by the broken line in Figure 9. As long as they overlap (for example, material B), the volume resistivity of the resin film is 10 6 to 10 12 Ω·cm.

FIG. 11 is a diagram for explaining a method for measuring the volume resistivity of a resin film to be measured. First, as shown in Figure (a),
The resin film 89 to be measured is cut into a square with a side of 100 squares,
The thickness at five arbitrary points within a circle with a radius of 50 u located at the center is measured using a micrometer, and the average value thereof is taken as the thickness of the resin film 89 to be measured. Next, as shown in FIG. 8B, a conductive pattern 90.91 is formed concentrically on the surface of the resin film 89 to be measured by applying a conductive paste such as Dotite D-550 manufactured by Fujikura Kasei Co., Ltd. form,
As shown in FIG. 8C, a conductive pattern 92 is similarly formed on the back side of the resin film 89 to be measured. Then, the volume resistivity of the resin film to be measured having conductive patterns formed on the front and back surfaces as described above is measured according to the method specified in JIS K6723.

By the way, in FIG. 1, upon peeling off the paper after the transfer, the charge removal from the resin film or the paper in the second transport section 443 is not performed instantaneously, but with a time constant depending on the volume resistivity of the resin film. Therefore, it takes a certain amount of time for the paper adsorption force to almost disappear. If the paper is forcibly peeled off by the peeling claw before static elimination of the resin film or the paper is completed, a phenomenon (explosion) in which the toner on the paper is scattered due to peeling discharge occurs.

In this example, the volume resistivity of the resin film is 10'2Ω・Cf
Since it is set smaller than f1, the above time constant is set to 0.
The time can be set to about 1 to 1.0 seconds, and when the peripheral speed of the transfer drum is about 150 ua/sec, the paper adsorption force at the peeling position can be eliminated with sufficient margin.

In other words, to explain with reference to FIG. 6, the changeover switch 86 is switched at a timing such that the paper adsorption force at the peeling position becomes approximately 0 according to the time constant of the resin film 68, and the second conveyance section 443 is By early grounding all corresponding electrodes, explosion can be prevented from occurring.

FIG. 12 is a side view of an electrostatic transfer transfer device showing another embodiment. This device includes a resin film 94 formed in the shape of an endless belt, and a pair of rollers 96.9 on which the resin film 94 is mounted.
8 and the horizontal surface of the resin film 94, respectively.
A cyan photoreceptor 100, a magenta photoreceptor 102, a yellow emergency photoreceptor 104, and a resin film 94 are used together with the photoreceptors 100, 102, and 104, on which the same original image is reproduced using magenta and yellow toners. Elastic rollers 106, 106, and 110 that rotate while pinching each other, and a brush power supply device 1 that supplies a predetermined voltage to electrodes provided inside the resin film 94 at the transfer position and paper conveyance position.
12. Incidentally, the electrical connection of the brush of the brush power supply device 112 and the arrangement of the electrodes can be performed according to each of the previous embodiments, so the explanation thereof will be omitted.

When the paper 40 is fed from the paper cassette 38 by the feed roller 36, the leading edge of the paper is detected by a paper feed sensor (not shown), and this detection causes each photoreceptor 100, 1 to
The timing of image writing to 02 and 104 is determined. At the same time, a predetermined electric field is applied by the brush power supply device 112 to the paper transport position and the transfer position. When the paper adsorbed to the resin film 9 passes directly under the photoreceptors 100, 102, and 104, a cyan image, a magenta image, and a yellow image are transferred to the paper, respectively, and as a result, multiple transfer images of the same image are formed. The photoreceptor 100.102.104 has
Image writing is performed sequentially with a delay corresponding to the conveyance time of the paper, and control is performed so that each of the three colors overlaps. The paper on which multiple transfer has been completed is further sent to a fixing device, where fixing is performed.

Effects of the Invention As detailed above, according to the configuration of the present invention (1), the state in which charges are injected into a specific position of the paper at the paper transport position is not maintained until the transfer position. This has the effect of suppressing the occurrence of electrode patterns. Further, according to the configuration of the present invention (2), the volume resistivity of the resin film is made smaller than 10120 cm, so that
The generation of electrode patterns can be effectively prevented, and the same volume resistivity is greater than 106 Ωcm.
This has the effect of preventing damage to the photoreceptor or resin film due to discharge.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway side view of an electrostatic transfer transfer device showing an embodiment of the present invention, Fig. 2 is an enlarged view of the broken part in Fig. 1, and Fig. 3 is a view taken along line I-III in Fig. 1. 4 is a partial perspective view of the transfer drum shown in FIG. 1, FIG. 5 is a sectional view showing a specific configuration example of the electrode shown in FIG. 4, and FIG. 6 is a partial perspective view of the transfer drum shown in FIG. FIG. 7 is an explanatory diagram of the power supply section of the device shown in FIG. 1. FIG. 8 is the relationship between the spark generation rate, the degree of electrode pattern generation, and the volume resistivity of the resin film. Figure 9 is a graph to explain the electric field dependence of volume resistivity, Figure 10 is an explanatory diagram showing a transfer model, and Figure 11 is a graph to explain the method for measuring the volume resistivity of a resin film. FIG. 12 is a side view of an electrostatic transfer transfer device showing another embodiment of the present invention, and FIGS. 13 to 16 are diagrams for explaining the prior art. 0... Photoreceptor, 2... Transfer drum, 4.112... Brush power supply device, 6... Resin film, 8... Electrode, 0... Transfer brush, 8. ...First suction brush, 4...Second suction brush. Applicant: Fuji Xerox Co., Ltd. Agent: Patent Attorney Ko Matsumoto゛Monday ear part 1; Applied voltage (V/cm) Fig. 11 Fig. d (b) (C) Fig. 12 Fig. 15 Fig. 13 Fig. 14

Claims (2)

[Claims] (1) A semiconductive resin film that moves while keeping the paper on which the toner image of the photoreceptor is transferred in close contact with the outer surface at least at the transfer position, and a plurality of electrodes arranged in parallel at regular intervals inside this resin film. a transfer power supply means that contacts one of the electrodes that has moved to the transfer position and supplies a voltage with a polarity opposite to that of the toner; and one of the electrodes that has moved to the paper conveyance position; An electrostatic transfer transfer device comprising: a power supply means for sucking paper that alternately supplies a high voltage and a low voltage. (2) The volume resistivity of the resin film is 10^6Ω・cm to 10
The electrostatic transfer transfer device according to claim 1, characterized in that the resistance is ^1^2 Ω·cm.