JP2897960B2 - Suction device for sheet members, etc., suction method for sheet members, etc., image recording device, and document handling device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suction device for holding and adsorbing a sheet member such as a transfer sheet and a copy original of an electrostatic recording apparatus, a method for adsorbing the sheet member, and a method for adsorbing the sheet member. The present invention relates to an image recording apparatus and a document handling apparatus for performing the operation.

Prior art As a color copier using the electrostatographic process,
A color copying machine of a color separation image superimposing transfer system in which toner images of different colors sequentially formed on one photoreceptor are superimposed and transferred on the same transfer paper while being aligned and fixed to obtain a color copy. It has been known. In a color copying machine of this type, the transfer sheet is reciprocated and transported a plurality of times at a transfer section in contact with one photoconductor, or the transfer sheet is wrapped around a transfer drum and is rotated multiple times. In addition, the toner images of different colors are formed on a plurality of photoconductors at different timings, the transfer sections of the respective photoconductors are arranged in a straight line, and the transfer paper is conveyed so as to sequentially contact the transfer sections of the respective photoconductors. Also, a method of superimposing and transferring by superposition is known.

In the case where the transfer paper is reciprocated by passing through the transfer section of one photoconductor or the transfer paper is linearly transported by sequentially passing through the transfer sections of a plurality of photoconductors, the unfixed toner is transferred onto the transfer paper. Since the image is on the sheet, the sheet cannot be conveyed while being nipped by the conveying roller pair.

In addition to a color copying machine, a fixing device also has a heater in a monochrome copying machine such as a black-and-white copying machine. In order to prevent heat from being transmitted to the photoconductor and to deteriorate the photoconductor, the transfer position along the photoconductor and the fixing device The distance is considerably large, and the transfer paper carrying the unfixed toner image must be conveyed therebetween.

As a transporting means of the transfer paper carrying the unfixed toner image as described above, a belt which moves and holds the transfer paper on the surface of a circulating endless belt so that the back surface of the toner image carrying surface does not come in close contact with and displaces. The method of transporting the transfer paper by entrainment is widely used.

As a method of holding and transporting a sheet such as a transfer sheet so as not to be in close contact with an endless belt, the following method has conventionally been adopted.

(A) Air suction system The endless belt is provided with a number of holes or is composed of a plurality of belts, and suctions air from a gap between adjacent belts into a suction box provided inside the belt, thereby seating the sheet on the belt surface. To hold and transport.

In this method, an air pump and an air passage are required for sucking air, and there is a disadvantage that the device becomes large.

(B) Grip method A gripper is provided on a belt, and the leading end of a fed sheet is gripped by the gripper to hold and convey the sheet.

In this method, the operation time of the grip is required, and it is difficult to continuously convey the sheet at a high speed.
There is a problem that a conveyance jam occurs due to a gripper grip error.

(C) Method using an electric double layer method A method often used for a transfer belt used in an electrostatic recording apparatus, and an electric double layer is formed on a layer including a belt and a sheet by corona charging or the like to form a sheet. The transfer belt is electrostatically attracted to the transfer belt, held and transferred. Normally, the paper feed resist linear speed of the copier is slightly faster than the process linear speed, so the paper film may cause a transfer deviation at the leading edge of the transfer paper. There is, however, the fact that it has not been sufficiently solved.

Further, when the sheet is simply used for conveyance, the sheet is held and conveyed to the belt by the electric double layer formed by the first corona charge. However, once the sheet is separated from the belt, the holding force is lost and the conveyance is performed. Since the charge on the belt remains, the second sheet must be recharged after the charge of the conveyor belt is removed, which is not practical.

(D) Comb-type electrode embedding method A sheet holding method that is often used in pen plotters and the like, in which two comb-type electrodes are embedded in a dielectric belt so that each tooth meshes with a (+). This is a method of applying the voltage (-).

This method is not only high in cost due to the above configuration, but also difficult to form on an endless belt. Further, even a belt-shaped one is not suitable because the transfer belt of the electrostatic recording apparatus has an adverse effect such as a reduction in transfer efficiency and the occurrence of transfer unevenness due to embedded electrodes. In addition, there is a problem in durability in terms of disconnection of the comb-shaped electrode.

In an electrostatic recording apparatus, an endless belt is used to convey a sheet. In addition to the above-described transfer / conveying apparatus belt, an automatic document feeding apparatus automatically feeds a document onto a contact glass of a copying machine or a document reading apparatus. Document feeder (Automatic Docu
ment Feedre: ADF) conveyor belt.

Currently used ADF transport belts include:
A rubber belt with a high coefficient of friction that is driven while the original is pressed against the surface of the contact glass is used,
When a document is conveyed while being pressed against a contact glass surface using a transfer belt made of a rubber-based material, there is a disadvantage that the surface is easily stained by contact with the document and the contact glass, and dirt is not easily removed from the belt surface. Furthermore, if the original is a highly translucent tracing paper or thin paper, the dirt pattern is also read and exposed, and the quality of the copied image and the reproduced image is degraded. Has become.

Therefore, it has been proposed to mix an antifouling agent into the material of the belt, apply an antifouling oil, or contact a cleaning blade in order to make the belt less likely to become dirty. The fact is that the effect is low and the durability is lacking.

On the other hand, some devices that utilize an electrostatic attraction force without using a rubber belt as a transport belt have been proposed.

For example, Japanese Patent Application Laid-Open No. 53-116825 proposes a device for burying a pattern electrode in an insulating belt and applying a voltage to the electrode to attract and transport a document by electrostatic force as an ADF transport belt. I have. However, the structure of the endless belt in which the pattern electrode is embedded and the means for applying a high voltage to the rotating part are complicated, which not only increases the cost, but also breaks the pattern electrode and feeds power due to bending at the roller winding part. There is a problem in durability such as abrasion of parts.

Japanese Patent Application Laid-Open No. 63-288843 also provides a document conveying belt charging means and a means for adjusting the distance between the belt and the surface of the contact glass. If possible, there has been proposed an apparatus capable of charging a transport belt by a charging unit with a wider interval to electrostatically attract and transport a document. However, the charging method described in this publication is based on the application of a DC voltage, and a uniform charging by this method does not provide a strong suction force. It is difficult to transport and hold it from above.

Japanese Patent Application Laid-Open No. 63-288844 discloses that the surface of the conveyor belt in contact with the member to be conveyed is formed of an amorphous silicon film layer to prevent contamination of the conveyor belt surface.
In addition, a means has been proposed in which means for charging the surface of the amorphous silicon layer is provided so that a member to be conveyed can be electrostatically attracted and conveyed.

However, this method requires the formation of a belt by depositing amorphous silicon on a conductive substrate, and has the disadvantage of increasing the cost of the belt itself.Since amorphous silicon has photoconductivity, it is absorbed by light irradiation. The power changes. Therefore, when used for an ADF transport belt, the potential (adhesive force) after exposure of the original changes depending on the type of paper and the number of repeats, and a problem such as occurrence of jams during discharge occurs.

DISCLOSURE OF THE INVENTION The present invention has been made in view of the above-described problems of various conventional sheet holding and conveying systems, and has a simple configuration which can reliably hold a sheet or the like by suction, and is low cost, compact, and highly durable. It is an object of the present invention to provide a sheet sucking apparatus having a property, a method of sucking such a sheet, and an image recording apparatus and a document handling apparatus for performing such sucking.

Means for Solving the Problems The present invention solves the above-mentioned problems by contacting a member for holding a sheet member or the like and a surface of the holding member on the side where the sheet member or the like is held, with respect to the suction device. A voltage application means for applying a voltage to the surface in such a state and forming an alternating charge density pattern on the surface is provided. In the suction method, a member for holding a sheet member or the like, a voltage application unit is brought into contact with the surface on the side where the sheet member or the like is held, and a voltage is applied to the surface in a state of contact.
An alternating charge density pattern is formed on the surface.

With respect to the image recording apparatus, a member for holding the transfer sheet or the original sheet is brought into contact with the surface of the holding member on which the sheet is held. The above problem is solved by having a voltage applying means for forming a charge density pattern. In a document handling apparatus, a member for holding a document sheet and a surface of the member on which the document sheet is held are brought into contact with each other, a voltage is applied to the surface in the contact state, and a charge density alternating with the surface is applied. The above problem is solved by having a voltage applying means for forming a pattern.

The alternating charge density pattern formed on the surface of the member holding the sheet member or the like on the side where the sheet member or the like is held,
An uneven electric field is formed near the surface of the holding member. The sheet member or the like is attracted to the holding member by the uneven electric field and is held so as not to be displaced.

According to a preferred embodiment, the charge density pattern is striped or checkered. It is preferable that the pitch of the charge density pattern is 0.1 to 20 mm. Further, it is preferable to apply an AC voltage that forms a charge density pattern in which the charge densities-[sigma] and + [sigma] are alternately and regularly arranged, or a non-uniform alternating voltage. The voltage applying means is preferably a roller-shaped electrode or a blade-shaped electrode.

The member holding the sheet member or the like is made of a high volume resistor, in which the charge density pattern formed on the surface is difficult to disappear, especially 10 ¹⁶ to
With a volume resistance of 10 ¹⁷ Ωcm, a plurality of sheets can be conveyed continuously. Further, the volume resistance is such that the surface potential of the member holding the sheet member or the like is attenuated to half or less of the surface potential of the member during the time required from the position where the voltage is applied to the separation position of the sheet member or the like. If it is a body, the charge density pattern is sufficiently attenuated at the separation position of the sheet member or the like conveyed by the holding member, and the sheet member or the like can be easily separated.

For example, if the holding member is used as a transport belt for transporting a copy original onto a contact glass surface of a copying machine or the like, and if the distance between the belt and the contact glass surface is set to be equal to or greater than the maximum thickness of the original to be used, The original is electrostatically attracted to the surface of the endless belt, and is transported over the contact glass in a state where the image side of the original and the contact glass surface are not in contact with each other. This not only increases the reliability and durability of the transport belt, but also Even if the original is written with a pencil, the contact glass is rubbed by the contact glass, and the contact glass is contaminated, so that it adheres to the surface of the belt and becomes dirty, and is not reproduced on a copy.

The above and other objects and features of the present invention will become apparent from the following detailed description with reference to the accompanying drawings.

DETAILED DESCRIPTION OF THE INVENTION Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a diagram showing one embodiment of the basic configuration of the present invention.

A transport belt 2 for holding and transporting a sheet 1 such as transfer paper is configured as an endless belt made of a dielectric material, and is wound and supported by a support roller 4 and a drive roller 4 '. The support roller 4 is made of metal and grounded. As shown in FIG. 2A, an electrode roller 3 for forming a charge pattern is provided so as to be in contact with the outer surface of the conveyor belt 2 at a position wound around the support roller 4, and the electrode roller 3 is provided with an AC power supply 5. AHz AC voltage is applied. The support roller 4 serves as a counter electrode for that purpose.

As shown in FIG. 2 (b), the electrode for forming a charge pattern may be a blade-shaped electrode 3 'whose tip is brought into sliding contact with the outer surface of the conveyor belt 2 at a position wound around the support roller 4.

The transport belt 2 is moved at a constant speed v mm / s in the direction of the arrow by the driving roller 4 ′, and the sheet feeding position of the sheet 1 is located downstream of the contact position of the electrode 3 with respect to the moving direction of the transport belt. , And is in a range in contact with the support roller 4 as a counter electrode.

Therefore, before the sheet 1 is fed to the surface of the conveyor belt 2, an AC voltage is applied from the AC power supply 5 via the electrode 3, whereby the surface of the conveyor belt 2 is applied as shown in FIG. As shown in a), a charge density pattern in which the charge densities-[sigma] and + [sigma] are alternately arranged at a pitch of v / A mm is formed. A similar charge density pattern is formed on the back surface of the conveyor belt 2 with a phase shift of 180 °.

With the charge density pattern thus formed, the third
As shown in the figure, an uneven electric field is formed near the surface of the belt 2. The force acting on the unit volume of the dielectric material of the sheet 1 due to this electric field is expressed as follows using the Maxwell's stress tensor, and the sheet 1 is applied to the transport belt 2 by a component fx perpendicular to the sheet surface. It is electrostatically attracted, held without displacement, and carried along with the conveyor belt 2 to be conveyed.

Assuming that the direction perpendicular to the sheet surface is x, the conveying direction is y, and the direction perpendicular to the conveying direction in the sheet surface is z, the component forces fx, fy in the x, y, and z directions of the force acting on the unit volume of the dielectric. , fz are as follows, respectively.

In the above equation, E is the electric field, D is the electric flux density,
x, y, and z indicate components in the respective directions.

The applied voltage may be obtained by superimposing a DC component on an AC voltage.

Further, as shown in FIG. 2 (b), a non-uniform alternating voltage is applied as a power source for outputting a non-uniform alternating voltage without using a power source 5 'for applying a voltage to the conveyor belt 2 as a regular AC power source. In this case, a charge density pattern in which the pitch between the (−) charge and the (+) charge is non-uniform depending on the location is formed on the front surface of the conveyor belt 2, and the reverse polarity is the same as that of the front surface on the back surface. A pattern is formed.

In each of the above examples, the charge density pattern is formed in a stripe shape, but may be formed in a checkered pattern or the like.

However, in any case, a sheet holding / transporting ability that is the same as that of the above-described example can be obtained.

The sheet holding force of the conveyor belt can be measured as follows.

As shown in FIG. 8, for example, A3 size plain paper 1 is fed to the conveyor belt 2 according to the size of the conveyor belt, and when the contact length between the paper and the conveyor belt becomes 100 mm, ie, the contact area Is 300 cm ² , the tensile strength is measured with a spring scale M attached to the rear end of the paper 1 and is used as a holding force.

Next, the results of measuring the relationship between the pitch of the charge pattern formed on the conveyor belt and the applied voltage and the holding force (tensile force measured by a spring) with respect to the conveyor belts having several thicknesses by the above-described method are shown in FIG. This will be described with reference to FIGS.

PET with volume resistance of 10 ¹⁶ to 10 ¹⁷ Ωcm
(Polyethylene phthalate trade name Mylar) Using a single-layer type film (thickness: 25 μm, 50 μm, 75 μm), the belt conveyance was 120 mm / s, and the attraction force was measured.

FIG. 4 shows the results of measuring the attraction force for each of the above-mentioned belts while keeping the amplitude of the AC voltage constant (4 kVp-p) and changing the applied frequency. As a result, when the pitch of the stripe shape was set in the range of 0.1 mm to 20 mm, a good suction force (1
kg f).

FIG. 5 shows the results of measuring the attraction force while changing the applied voltage while keeping the applied frequency constant (20 Hz). As a result, in the case of the 75 μm belt which is easy to handle in terms of strength, a good attraction force was obtained at a peak value of 2.5 kVp-p or more from the peak value, but as can be seen from the graph, as the belt thickness became thinner. , The rise of the adsorption force shifted to the lower voltage side. In addition, the charge density pattern was not formed on the belts at an applied voltage at which no attraction force was generated in each belt. For this reason, in order for each belt to generate an attraction force, at least an applied voltage higher than the charging start voltage is necessary. By increasing the voltage from the peak value to the peak value by 500 Vp-p or more from the charging start voltage. It was found that a desired adsorption force was obtained.

Embodiment 1 An embodiment in which the present invention is applied to a conveying device of an electrostatic recording apparatus using the same configuration as that of FIG. 1 will be described. The transport belt is configured as a one-layer type high-resistance PET film (75 μm) endless belt, and is rotatably supported by a drive roller and a support roller. The support roller is made of metal and is grounded, the transport belt is wound around the outer surface, and a roller-shaped charge pattern forming electrode is provided at the position in contact with the outer surface of the transport belt, and the load electrode is provided with an AC power supply of 4 kVp- An alternating voltage of p, 60 Hz is applied. In addition, the transfer conveyance belt is moved at a constant speed of 120 mm / s in the direction of the arrow by the driving roller,
The transfer paper is fed at a position downstream of the electrode contact position with respect to the moving direction of the transport belt and at a position in contact with the transport belt on the support roller. The transport distance was set to 240 mm. Therefore, before the transfer paper is fed to the surface of the transport belt, an AC voltage is applied from the AC power supply through the electrodes, whereby a charge density pattern is formed at a pitch of 2 mm on the surface of the belt. To hold and convey the transfer paper. Thereafter, the transfer paper is separated from the drive roller unit at the separation position, and is fixed to a fixing device by a guide plate.

However, since the transport belt has a high resistance, the charge density pattern formed once hardly disappears, and a plurality of sheets can be transported continuously. However, the charge density pattern is not attenuated at the separation point, and a separation claw is required for separating the paper. Therefore, an embodiment that does not require a separation claw at a separation point will be described below.

Example 2 The transport belt was a single-layer type dielectric film (100 μm).
m) It is configured as an endless belt, and is rotatably supported by a driving roller and a supporting roller. The volume resistivity of this dielectric film was 10 ⁸ Ω · cm, and it was a polyester film in which carbon was dispersed. The support roller is made of metal and is grounded, and the transport belt is wound around the outer surface, and at that position, a roller-shaped charge pattern forming electrode is provided in contact with the outer surface of the transport belt, and the electrode is provided with a 4 kVp-
An alternating voltage of p, 60 Hz is applied. Further, the transfer conveyance belt is driven at a constant speed (v)
The transfer paper moves at 0 mm / s, and the transfer paper is fed at a position in contact with the conveyor belt.

Also, the distance (l) from the electrode roller to the paper separation point is
The belt charged to 240 mm and reached by the electrode roller reaches the separation point after 2 seconds (l / v). Before the transfer paper is fed to the surface of the conveyor belt, an AC electrode is applied from an AC power supply via an electrode, whereby a charge density pattern is formed at a 2 mm pitch on the surface of the belt. To hold and convey the transfer paper.

At this time, since the transport belt has a medium resistance, the charge density pattern attenuates with time. The damping is expressed as volume resistance R,
When expressed as the relative dielectric constant x and the surface potential And decays exponentially. FIG. 6 shows the relative dielectric constant x
3 is a decay curve of surface potential due to volume resistance calculated assuming that 3 is 3. FIG. 7 shows the relationship between volume resistance and time when the surface potential attenuates to 1/10 and 1/100. From this graph, the surface potential is attenuated to 1/100 after 2 seconds. By setting it to 1.64 × 10 ⁸ Ωcm, the charge density pattern is almost completely attenuated at the transfer paper separation position. Separation of paper is facilitated, and separation errors can be reduced. In this embodiment, a resistor that attenuates to 1/100 was selected, but even a half reduced the separation error. Thereafter, the transfer paper is separated from the driving roller unit at the separation position, and is guided to a fixing device by a guide plate and fixed.

Next, FIG. 9 is a view showing an embodiment of another basic configuration of the present invention, in which the transport belt 2 has a conductive layer 2b provided on the entire inner peripheral surface of a dielectric layer 2a. The transport belt 2 is wound and supported by a drive roller 4 'and a grounded metal support roller 4 as in the transport device of the first invention. An electrode 3 for forming a charge pattern connected to an AC power supply 5 is in contact with the outer surface of the transport belt 2 at a position where the belt 3 is wound around the support roller 4.

With this configuration, (+) and (-) charge density patterns are regularly formed on the outer surface of the dielectric layer of the conveyor belt 2 as shown in FIG. Also in this case, as shown in FIG. 10 (b), by using a power supply 5 'for outputting a non-uniform alternating voltage as a power supply for forming a charge pattern, a non-uniform charge density pattern is formed on the outer surface of the dielectric layer 2a. Is formed. FIGS. 10 (a) and 10 (b) show an example in which a blade is used as the electrode 3, but it is needless to say that the electrode roller may be in contact with the outer surface of the belt.

In the configuration of the present invention, since the conductive layer 2b is provided on the entire inner peripheral surface of the transport belt and is grounded via the support roller 4, the electric charge induced also at the interface between the dielectric layer 2a and the conductive layer is provided. A pattern is formed. Further, the sheet feeding position of the sheet 1 is not limited to the range wound around the support roller 4 as long as the sheet 1 is located downstream from the contact position of the electrode 3.

 Next, an embodiment of this configuration will be described.

Embodiment 3 An embodiment in which the invention having the basic configuration shown in FIG. 9 is used in a transport device of an electrostatic recording apparatus will be described. The transport belt 2 is of a two-layer type, and a surface layer 2a is constituted by a dielectric film (40 μm), and a lower layer 2b is constituted by an end deposit made of aluminum deposition (10 μm), and is rotatably supported by a drive roller and a support roller. The volume resistance of this dielectric was 10 ⁸ Ω · cm.
The support roller 4 is made of metal and is grounded.
Is wound, and a charge pattern forming electrode 3 on a roller is provided in contact with the outer surface of the transport belt at that position. An alternating voltage of ± 2 kV, 60 Hz is applied to the electrodes from an AC power supply. The transfer belt is moved at a constant speed of 120 mm / s in the direction of the arrow by the driving roller 4 ', and the paper feed position of the transfer paper is downstream from the contact position of the electrode with respect to the movement direction of the transfer belt. The transfer distance is 240 mm. Therefore, before the transfer paper is fed to the surface of the transport belt, an AC voltage is applied from the AC power supply through the electrodes, whereby a charge density pattern is formed at a pitch of 2 mm on the surface of the belt. You. The transfer paper is fed onto the transport belt from the paper feed position, and is held and transported by the transport belt.
At this time, since the upper layer of the conveyor belt has a medium resistance, the charge density pattern is attenuated to less than half at the separation position of the transfer paper, and the transfer paper is easily separated. Thereafter, the transfer sheet separated from the transfer belt is transferred to a transfer position, and the toner image on the photoconductor is transferred to the transfer sheet.

Further, in the two-layer type conveyor belt of this embodiment, since there is an aluminum layer as a conductive layer as a lower layer, the paper feed position need only be limited to the downstream side from the contact position of the electrode, and even at high temperature and high humidity. Sufficient adsorption power was obtained.

The sheet conveying device according to each of the above embodiments is not limited to the transfer sheet conveying device described in each of the above embodiments, but also an automatic document feeder (Automatic Document Feeder) that automatically conveys a document onto a contact glass of a copying machine. It can also be used for conveyor belts (Feeder: ADF).

An embodiment in which the present invention is applied to an ADF conveyance belt will be described below.

Fourth Embodiment FIG. 11 is a diagram showing a transport belt of an ADF to which the present invention is applied and the vicinity thereof. An ADF 11 is provided so as to cover the upper surface of a contact glass 10 provided on the top surface of the copying machine body 9 and to contact the transport belt 12. The conveyor belt 12 is made of a dielectric sheet such as a PET film, and is stretched so that the running portion facing the contact glass 10 is stretched between the driving roller 14 and the driven roller 15 so as to be horizontal and strictly parallel to the contact glass. It has been like that. A gap is provided between the outer surface of the lower running portion of the conveyor belt 12 and the upper surface of the contact glass 10, and the gap is at least equal to or greater than the maximum thickness of the original to be used.

A charge pattern forming device 16 is provided in contact with the belt 12 wound around the driven roller 15 on the document insertion side, and an AC voltage is applied from an AC power supply 17. The roller 15 also serves as a counter electrode. Documents on the document feed table 18 are picked up by roller 1
9, the sheet is fed to the belt 12 within the range wound around the roller 15 downstream of the charge pattern forming device 16 in the belt circumferential direction via the conveying roller 20 and the entrance guide 21.

A charge density pattern having a pitch of v / A mm is formed on the conveyor belt 12 by the charge pattern forming device 16 and the AC power supply 17 (v is the belt speed in mm / sec, and A is the cycle Hz of the applied AC voltage).

Therefore, the document fed from the document feed table 18 is electrostatically attracted to the transport belt and transported for the reason described above. Since a gap equal to or greater than the maximum thickness of the original is provided between the contact glass 10 and the transport belt 12, the original surface is transported to a predetermined position without rubbing against the surface of the contact glass 10. After exposure, the original is conveyed in the discharge direction by the conveyor belt 12, separated from the conveyor belt 12 by curvature separation at the position of the drive roller 14, and the exit guide is provided.
After passing through 22, the sheet is discharged to a document receiver 24 by a discharge roller 23.

If the original is a book original, flip up the ADF and place the original on the contact glass 10 by hand, and use the ADF as the original platen or use another platen as is conventionally known. is there.

In the ADF of this embodiment, a small gap is formed between the surface of the contact glass and the document surface, but the amount is small, and is sufficiently within the so-called depth of field of the lens.
The out-of-focus problem does not occur practically.

However, it is also possible to finely adjust the position of the lens of the exposure system based on the thickness of the original paper and correct it.

FIG. 12 shows an example of a copying machine provided with a transfer paper transport belt and a document transport belt according to the present invention. In this copying machine, the original is fed onto the contact glass 10 by the ADF 11. The ADF 11 is provided with a document conveying belt 12 according to the present invention.

The manuscript fed onto the contact glass 10 is exposed
An image is formed on the photosensitive drum 31 through 30 to form a latent image,
A toner image is formed by a known electrophotographic process.

Transfer paper feed cassettes 32 are provided in three stages below the copying machine, and the transfer paper fed from each paper feed cassette is fed to the photoconductor 31 via the vertical transport belt 33 according to the present invention. After the toner image is transferred, the transfer paper is sent to the fixing unit 35 via the transport belt 34 according to the present invention, and after being fixed, is discharged to the paper discharge tray 36, and the copying is completed. An alternating voltage is applied to each of the conveyor belts 12, 33, and 34 from the AC power supply 5 through the electrodes 3 and 16.

The transport device of the present invention is not limited to a sheet-like member such as a transfer sheet or a document, but can hold and transport a dielectric member having a large flat surface and capable of being supported on this surface.

Effects As described above, according to the present invention, the sheet-like member can be reliably held by the simple structure and electrostatically attracted and held without being shifted, and the transfer deviation is prevented when the transferred object is the transfer paper. In the case where the conveyed object is a document conveyed on the contact glass of a copying machine, not only the reliability and durability are increased without rubbing with the contact glass, but also the reproduction of the belt dirt and the dirt on the copy is prevented. The effect is also obtained for improving the copy quality. In general, it is possible to reduce the size and cost of the apparatus. In addition, since the charge pattern is formed by the charge pattern forming electrode and the sheet is held by this, durability and reliability are improved, and when a material whose charge density pattern is hardly attenuated is used, a plurality of sheets are used. Can be continuously conveyed. Conversely, when a material whose charge density pattern is easily attenuated is used, the separability of the conveyed sheet is improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing the basic structure of the first invention, FIGS. 2 (a), (b) and 3 are explanatory views for explaining the operation thereof, and FIG. 4 is a tensile force with respect to the charge pattern and pitch. FIG. 5 is a curve diagram showing a characteristic of a tensile force with respect to an applied voltage, FIG. 6 is a curve diagram showing an example of a surface potential decay curve over time due to the volume resistance of the conveyor belt, and FIG. FIG. 7 is a curve diagram showing the relationship between volume resistance and time when the surface potential is attenuated to a predetermined ratio, FIG. 8 is an explanatory diagram showing a holding force measuring means of the transport device according to the present invention,
9 is an explanatory view showing the basic structure of the second invention, FIGS. 10 (a) and 10 (b) are explanatory views for explaining the operation thereof, and FIG. 11 is an embodiment in which the present invention is applied to an automatic document feeder. FIG. 12 is a cross-sectional view showing an example of an electrophotographic copying machine provided with a sheet conveying member according to the present invention. DESCRIPTION OF SYMBOLS 1 ... Sheet 2 ... Conveyer belt 2a ... Dielectric layer 2b ... Conductive layer 3,3 ', 16 ... Charge pattern forming electrode 4,15 ... Belt winding roller and counter electrode 5,17 ... AC Power supply 5 'Power supply for applying alternating voltage 6 Photoconductor 7 Transfer charger 10 Contact glass 11 Automatic document feeder 12 Document transport belt 31 Photoconductor 33, 34 Transfer Paper transport belt

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Kenichi Mizuma 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Yoshihiro Sakai 1-3-6 Nakamagome, Ota-ku, Tokyo No. Ricoh Co., Ltd. (72) Inventor Noriyuki Kimura 1-3-6 Nakamagome, Ota-ku, Tokyo Incorporation Ricoh Co., Ltd. (72) Kazushige Taguchi 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (72) Inventor Katsuo Sakai 1-3-6 Nakamagome, Ota-ku, Tokyo Inside Ricoh Co., Ltd. (56) References JP-A-58-76849 (JP, A) JP-A-59- 227657 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) B65H 5 / 02,5 / 00 G03G 15/00

Claims (17)

(57) [Claims] 1. A member for holding a sheet member or the like, and a surface of the holding member on which the sheet member or the like is held is contacted, and a voltage is applied to the surface in the contact state, and an alternating voltage is applied to the surface. And a voltage applying means for forming a charge density pattern. 2. The suction device according to claim 1, wherein the charge density pattern is a stripe. 3. The suction device according to claim 1, wherein the charge density pattern is a checkered pattern. 4. The charge density pattern has a pitch of 0.1 to 20 m.
The suction device for a sheet member or the like according to claim 2, wherein m is m. 5. The method according to claim 1, wherein the voltage applying means comprises a charge density of -σ, + σ.
2. An adsorption apparatus for a sheet member or the like according to claim 1, wherein an AC voltage is applied such that a charge density pattern is formed alternately and regularly. 6. The apparatus according to claim 1, wherein said voltage applying means applies a non-uniform alternating voltage. 7. The apparatus according to claim 1, wherein said voltage applying means is a roller-shaped electrode. 8. The apparatus according to claim 1, wherein said voltage applying means is a blade electrode. 9. A suction device for a sheet member or the like according to claim 1, wherein the member holding the sheet member or the like is a high volume resistor in which a charge density pattern formed on the surface is difficult to be erased. 10. The suction device for a sheet member or the like according to claim 9, wherein the volume resistance is 10 ¹⁶ to 10 ¹⁷ Ωcm. 11. A member for holding said sheet member or the like, wherein the surface potential of said member during the time required from the position where a voltage is applied to said member to the separation position of said sheet member or the like is half of that at the beginning of application. The suction device for a sheet member or the like according to claim 1, wherein the suction device is a volume resistor that attenuates below. 12. A voltage applying means is brought into contact with the surface of the member holding the sheet member or the like on the side on which the sheet member or the like is held, and a voltage is applied to the surface in the contact state to alternate with the surface. A method for adsorbing a sheet member or the like, wherein a charge density pattern is formed. 13. An alternate charge density pattern is formed on one surface of a member holding a sheet member or the like, and a similar charge density pattern is formed on the other surface with a 180 ° phase shift. Item 13. The method for adsorbing a sheet member or the like according to Item 12. 14. A current density pattern formed on a surface of a member holding a sheet member or the like is a charge density pattern in which charge densities -.sigma. And + .sigma. Are alternately and regularly arranged. Or the adsorption method of a sheet member or the like according to 13. 15. A member for holding a transfer sheet, and a surface of the member for holding the transfer sheet in contact with the surface on which the transfer sheet is held. An image recording apparatus, comprising: voltage applying means for forming a pattern. 16. A member for holding an original sheet and a surface of the holding member on which the original sheet is held, and a voltage is applied to the surface in the contact state, and a charge density alternating with the surface is applied. An image recording apparatus, comprising: voltage applying means for forming a pattern. 17. A member for holding an original sheet, and a surface of the holding member on which the original sheet is held is brought into contact, and a voltage is applied to the surface while in contact with the member, and a charge density alternating with the surface is provided. A document handling apparatus, comprising: voltage applying means for forming a pattern.