JPH0444511Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention provides a sheet adsorbent made of a dielectric or a semiconductor with a plurality of sheet electrodes spaced apart from each other in the direction of movement thereof, and applies a voltage to each sheet electrode. The present invention relates to a sheet conveying device that moves a sheet such as paper while adsorbing it by applying a pressure.

2. Description of the Related Art Sheet suction bodies in conventional sheet conveyance devices of this type have been proposed for paper holding in printers, paper feeding in electrophotography, magnetography, etc., paper conveyance, and sheet conveyance transfer devices.

First, a conventional technique will be described using a paper conveyance transfer device of an electrophotographic copying machine as an example.

FIG. 6 and FIG. 7 show a paper conveyance section of a conventional paper conveyance transfer device proposed as a sheet conveyance device for an electrophotographic copying machine. A large number of sheet electrodes C ₁ are arranged at predetermined intervals over the entire length of b.
C ₂ and C ₃ are provided by printing. Then, this sheet electrode is alternately attached to the semiconductive substrate b every three sheets.
It is made long enough to reach the edge of one side. On the other hand, on one side edge of the semiconductive substrate b on the side where the sheet electrode is printed, there is a positive brush electrode e connected to a DC power supply d.
However, on the other side edge, a grounded negative side brush electrode f is in contact over the entire length of the sheet conveyance section, and among the sheet electrodes C ₁ and ₃ , which are lengthened above, are lengthened to one side. The sheet electrode C ₃ has a positive potential, and the sheet electrode C ₁ extended to the other side has a negative potential. The sheet g is attracted to the surface of the sheet adsorbent a by the potential difference between the sheet electrodes C ₁ and C ₃ which are different in the longitudinal direction, and is conveyed as the sheet adsorbent a moves.

In addition, in the transfer section, the brush electrodes are arranged so that the voltage is applied only to the transfer area, and voltage is applied to all of the sheet electrodes C ₁ , C ₂ , and C ₃ that have moved to the transfer section, so that there is no transfer omission. (not shown) are arranged.

Problems to be Solved by the Invention When a sheet conveying device having the configuration shown in FIGS. 6 and 7 is used, the following problems occur.

That is, in the above conventional configuration, each sheet electrode C ₁ or C ₃ that is elongated in the same direction is always at the same potential, and the sheet being conveyed comes into contact with each sheet electrode C ₁ or C ₃ during the conveyance. ,
Electric charge accumulates on sheets such as recording paper that are being conveyed,
When the transfer is performed in the transfer section, high density areas and low density areas occur alternately at the pitch of the sheet electrodes C ₁ and C ₃ for conveyance. This phenomenon is remarkable for high resistance paper such as low water content paper.

Further, conventional paper conveyance devices have the following problems, which will be explained in the case where a dielectric substrate is used as a sheet adsorption member of the paper conveyance device.

In other words, it is common to have a structure in which a sheet adsorbing body formed in an endless shape (belt shape) is rotated, the sheet is adsorbed and conveyed by this, and the sheet is peeled off at a predetermined position. In this case, 1
When the first sheet is peeled off, an electric charge accumulates on the sheet adsorbent (belt), and no electric field is released from the sheet adsorbent, and the adsorption force disappears or becomes very weak, causing the second and subsequent sheets to be removed. Adsorption becomes impossible.

Countermeasures have been taken to address this problem, such as removing static electricity from the sheet adsorbing body after peeling and before adsorption, but this increases the cost and complicates the apparatus.

Means and Effects for Solving the Problems The present invention has been developed in view of the above-mentioned problems, and is based on the invention, in which the electric charge of the sheet electrode for sheet adsorption of the sheet adsorption body changes from positive to negative as the sheet adsorption body is transported. Therefore, the present invention aims to provide a sheet conveying device that prevents the accumulation of charge at the place where the adsorption force is generated, thereby preventing the occurrence of shading in the image at the transfer section. Alternatively, a sheet electrode is provided on a semiconductive endless sheet adsorbent, and a voltage is applied to the sheet electrode to adsorb the sheet to the surface of the sheet adsorbent, and as the sheet adsorbent moves, the sheet is attached to the surface of the sheet adsorbent. In the sheet conveyance device for conveying sheets, a large number of the sheet electrodes are arranged on a surface of the sheet suction body opposite to the sheet suction surface at intervals in the moving direction of the sheet suction body, and The means for applying voltage to the sheet electrode includes a high voltage electrode that contacts the sheet electrode and applies a high voltage to the sheet, and a low voltage electrode that contacts the sheet electrode and applies a low voltage to the sheet, and The high voltage electrode and the low voltage electrode are arranged alternately with respect to the moving direction of the sheet adsorbent,
For any of the sheet electrodes whose position changes due to movement of the sheet adsorbent,
The structure is such that high voltage and low voltage are applied alternately, and the sheet that is in contact with the other side of the sheet suction body is attracted to the sheet suction body due to the potential difference between each sheet electrode, and the sheet suction body It is conveyed as it moves. At this time, each sheet electrode of the sheet suction body alternately changes to high voltage and low voltage as the sheet suction body moves, and one place has a high potential,
Or the potential never becomes low.

Embodiment An embodiment of the present invention will be described based on FIGS. 1 to 5.

In the figure, 1 is a sheet adsorbent formed in a long strip shape.
This sheet suction body 1 is made of a semiconductive or dielectric base, and a large number of sheet electrodes 2 are arranged on the surface of the sheet suction body 1 opposite to the sheet suction surface to control the movement of the sheet suction body 1. They are provided by printing at intervals in the direction.

Reference numerals 3a and 3b are brush electrodes provided on the surface of the sheet adsorbent 1 on which the sheet electrode 2 is provided, and in contact with both end portions of the sheet electrode 2. A plurality of these brush electrodes 3a, 3b are arranged at equal intervals in the moving direction of the sheet adsorbent 1, and are arranged alternately in a staggered manner on both sides. The brush electrode 3a on one side is connected to a DC power source 4 to form a high voltage electrode, and the brush electrode 3b on the other side is grounded to form a low voltage electrode. The distance between each of the brush electrodes 3a and 3b is larger than the distance between the sheet electrodes 2, for example, the distance between six brush electrodes.
The distance between the sheets a and 3b in the moving direction of the sheet adsorbers 1 is equal to the distance between three sheet electrodes 2.

In the above configuration, the sheet adsorbent 1 is connected to the electrode 3
When moving relative to a and 3b, each sheet electrode 2 of the sheet adsorbent 1 sequentially comes into sliding contact with the electrodes 3a and 3b,
The potential of each sheet electrode 2 changes repeatedly in the order of positive → float → earth → positive → float... On the other hand, the sheet 5 placed on the surface of the sheet adsorbent 1
is attracted by the potential difference between the electrodes 3a and 3b facing each other on both sides in the moving direction, and is moved together with the sheet attracting member 1. At this time, the potential of the sheet electrode 2 facing the sheet 5 changes from plus → float → earth → float →... as described above, so the sheet 5
A specific charge never accumulates in the .

FIG. 3 shows a case where the sheet conveyance device of the present invention is used in a sheet conveyance transfer device of an electrophotographic copying machine.

In the figure, 6 is a photoreceptor, and a toner image is formed on the surface of this photoreceptor 6 by a process well known as an electrophotographic copying machine. Reference numeral 7 denotes a sheet adsorbent configured in the shape of an endless belt.
It is designed to touch the object and move in the same direction and at the same speed. A large number of sheet electrodes are provided on the back side of the sheet suction body 7, similar to those shown in FIGS. Brush electrodes 3a and 3b are provided alternately. Also, a transfer part brush electrode 9 is located at a position facing the photoreceptor 6.
is provided.

Therefore, the paper (sheet) fed from the paper feeder (not shown) to the sheet suction body 7 is transferred to the sheet suction body 7.
The toner image is attracted by the sheet adsorber 7 and conveyed as the sheet adsorbent 7 moves, and the toner image formed on the photoreceptor 6 is transferred to the transfer portion brush electrode 9 at the transfer portion that contacts the photoreceptor 6, and then to the next toner image. Transported to the process.

The resistance of the semiconductive substrate constituting the sheet adsorbent 7 is 10 ¹⁰ Ω·cm, the width of the sheet electrode 2 is 1 mm,
The interval between the sheet electrodes is 1 mm, the width of the brush electrodes 3a and 3b is 1.5 mm, the interval between the brush electrodes 3a and 3b in the moving direction of the sheet adsorbent 7 is 6 mm in terms of center distance, and the applied voltage is 1.5 kV. Further, the surface speed of the sheet adsorbent 7 was 80 mm/sec.

FIG. 4 shows the results of an experiment using the embodiment of the present invention shown in FIGS. 1 and 2 and the conventional example shown in FIGS. 6 and 7 with the same parameters. The transfer paper was conditioned at low temperature and low humidity, standard environment, and high temperature and high humidity, and copies were obtained using the two techniques described above. As a result, compared to the copy grade of the conventional apparatus shown by the dotted line, the apparatus of the present invention produced better copies on all sheets.

Next, an example in which the present invention is implemented in a sheet conveying device will be described based on FIG. 5.

In this embodiment, the resistance of the sheet adsorbent 10 formed into an endless belt is 10 ¹⁴ Ω·cm, and the brush electrode 3
The voltages applied from a and 3b are alternately +750V and -
750V, and the other parameters are the same as those explained in the embodiment of the paper conveyance transfer device.

In FIG. 5, the paper sent out from the paper feeder 11 is transferred to the sheet suction body 1 which rotates at 1200 mm/sec.
0 and transported.

According to this example, it was confirmed that even a sheet adsorbing member (sheet conveyance belt) using a dielectric substrate could also adsorb the second and subsequent sheets.

In each of the above embodiments, the electrodes are arranged on both sides of the sheet suction body in the width direction, but each electrode is placed on one side or in the middle of the sheet suction body with a high voltage,
It may be arranged alternately with low voltage.

Effects of the invention According to the invention, as the sheet adsorbers 1, 7, 10 move, the potential of the sheet electrodes 2 provided on the sheet adsorbers 1, 7, 10 changes, and the sheet adsorbers 1, 7, 10 change in potential. When the present invention is applied to a paper conveyance transfer device, it is possible to prevent the accumulation of electric charge on sheets conveyed in contact with this, and when the present invention is applied to a paper conveyance transfer device, all sheets of paper can be coated without any shading in the copy density regardless of temperature and humidity. I was able to get a good copy. Also, when applied to a paper conveyance device, there is no need to use a special static eliminator, and the second and subsequent sheets can be attracted and conveyed, and conventional problems can be solved with a simple configuration. .

Further, according to the present invention, the amount of brush electrodes 3a, 3b used can be reduced.

Further, according to the present invention, when used in a paper conveyance transfer device, there is no need to form the paper suction electrode in a sheet shape that is particularly long compared to the conventional method, and the invention can be made inexpensive and compact.

[Brief explanation of the drawing]

Figure 1 is a plan view of the main parts of this invention seen from the back side.
FIG. 2 is a side view, FIG. 3 is a front view showing the sheet conveyance transfer device, FIG. 4 is a diagram showing copy grade against paper humidity control conditions, FIG. 5 is a front view showing the sheet conveyance device, and FIG. The figure is a plan view of the main parts of the conventional example as seen from the back side, and FIG. 7 is a side view. 1 is a sheet adsorbent, 3 is an electrode, and 3a and 3b are brush electrodes.

Claims (1)

[Claims for Utility Model Registration] A sheet electrode is provided on a dielectric or semiconductive endless sheet adsorbent, and the sheet is adsorbed on the surface of the sheet adsorbent by applying a voltage to the sheet electrode. In the sheet conveying device that conveys the sheet as the sheet suction body moves, the sheet electrode is arranged on a surface of the sheet suction body opposite to the sheet suction surface at an interval in the moving direction of the sheet suction body. A large number of the sheet electrodes are arranged at intervals, and as a means for applying voltage to the sheet electrode, there are a high voltage electrode that contacts the sheet electrode and applies a high voltage to the sheet, and a high voltage electrode that contacts the sheet electrode and applies a low voltage to the sheet. low voltage electrodes are provided, and the high voltage electrodes and the low voltage electrodes are arranged alternately with respect to the moving direction of the sheet attracting body, and the positions of the high voltage electrodes and the low voltage electrodes change as the sheet attracting body moves. A sheet conveying device characterized in that a high voltage and a low voltage are alternately applied to arbitrary ones of the sheet electrodes.