JP2003237960A - Sheet feeder, automatic document reader, feeder and image forming device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sheet feeder, an automatic document reader, a feeder and an image forming device that can prevent multi-feeding and stabilize feeding without lowering productivity. <P>SOLUTION: The sheet feeder, the automatic document reader, the feeder and the image forming device have the following typical structure. An attraction belt unit 1 so designed that when a sheet is brought in contact with an attraction surface with a given electric charge formed, electrostatic force attracts the sheet to the attraction surface that feeds and carries it, comprises a physical property value measuring part 29 for detecting a physical property value of the fed sheet, a charging roller 10 for forming the electric charge on the attraction surface, and a control circuit 36 for controlling the electric charge formed by the charging roller 10 and an attraction time as a time for which the sheet is in contact with the attraction surface. The control circuit 36 controls the electric charge and the attraction time in dependence on the physical property values of the sheet. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a sheet conveying device for conveying a sheet material in a copying machine, a laser beam printer, a facsimile, etc., and an automatic document reading device, a feeding device, and an image forming apparatus having the same.

[0002]

2. Description of the Related Art Conventionally, as a technique for separating and conveying a sheet from a sheet bundle, a friction separation system is known in which the separation is performed by utilizing the frictional force between a rubber roller, a rubber belt and a sheet. However, it is known that this method causes great deterioration of rubber and has no durability. In addition, the air feeding method that uses air suction to separate air is not a separation method that uses friction, so it has durability, but it requires a large device, takes up space, and is noisy. Are known.

As a technique for solving these drawbacks, a feeding device utilizing electrostatic attraction has been proposed in Japanese Patent Application Laid-Open No. 9-67033. In this electrostatic attraction type feeder, an unequal electric field is formed on the dielectric belt to form an alternating electric charge having a predetermined pitch on the dielectric belt. And
By bringing the sheet into contact with the dielectric belt, the electric potential of the sheet is raised and an electric charge having an opposite polarity to that of the dielectric belt is formed on the sheet. The electric charges formed on the dielectric belt and the electric charges formed on the sheet are attracted by the Coulomb force, and the sheets are adsorbed on the dielectric belt and separated and conveyed one by one.

However, in the electrostatic adsorption type feeding device, when the thick paper is fed, it is necessary to considerably increase the charge amount of the dielectric belt so as to increase the attraction force.
However, if thin paper is fed under the conditions, not only the sheet to be attracted but also the second and subsequent sheets are attracted to the dielectric belt. It is considered that this is because the second and subsequent sheets are pulled by the dielectric belt because the second and subsequent sheets also have a large electric charge.
In order to solve this problem, the dielectric belt is kept in contact with the sheets for a predetermined time (hereinafter, adsorption time) to reduce the adsorption force of the second and subsequent sheets.

FIG. 20 is a graph showing the result of theoretically simulating the attenuation of the attraction force of the second thick sheet of paper to be attracted to the dielectric belt in the conventional electrostatic attraction type feeder. is there. 2 environment (23 ℃, 60% and 23 ℃,
It can be confirmed that the manner of attenuation is different when comparing the (5%) waste paper and the copy output paper at 20 ° C. and 60%. This is because the resistivity, which is the physical property value of paper, is different.

The weight of this thick paper is about 13 gf, whereas the belt suction force applied to the second sheet is 0 time.
It is about 0.4 gf from s. Therefore, the second sheet should not stick to the dielectric belt due to the relationship of 0.4 gf <13 gf.

FIG. 21 shows the attenuation of the suction force of the second thin paper sheet attracted to the dielectric belt. It can be confirmed that the belt suction force at time 0 s is greater than that of thick paper. This is because the electrostatic capacity of thin paper is sufficiently larger than that of thick paper.

As in the case of thick paper, the method of damping the suction force is
Differs depending on the conditions such as additional paper and copy output paper. The weight of the thin paper is about 3 gf with respect to this belt suction force (broken line in FIG. 21), and if the belt suction force is less than this broken line, it can be determined that the second sheet will not be sucked onto the dielectric belt, that is, will not be double fed. .

For example, 0.06 s for 60 ° C. paper at 23 ° C., 0.14 s for 23 ° C., 5% paper,
If copy output paper at 23 ° C and 60% is in contact with a dielectric belt for about 1.5 s, the attraction force of the second sheet to the dielectric belt is attenuated and the second sheet becomes dielectric. It should not stick to your body belt.

As described above, since the damping ratio of the suction force applied to the second sheet is different between the thick paper and the thin paper and between the bleached paper and the copy output paper, the suction time for separation is different. Therefore, in order to separate and convey all of thick paper, thin paper, copy output paper, bleached paper, etc., it is necessary to take a long adsorption time. For example, in the case of thin paper and thick paper shown in FIGS. 20 and 21, it is necessary to take the adsorption time of 1.5 s or more to separate and convey the thin copy output paper (23 ° C., 60%).

[0011]

However, in the above-mentioned conventional electrostatic attraction type feeding device, if the adsorption time is set to be long, the time required for one sheet feeding becomes long, and as a result, There is a problem that the productivity of the image forming apparatus equipped with the feeding device is significantly reduced.

Therefore, the present invention provides a sheet conveying device, an automatic document reading device, a feeding device and an image forming apparatus which can prevent double feeding and perform stable feeding without lowering productivity. The purpose is to

[0013]

In order to solve the above problems, a typical structure of a sheet conveying device, an automatic document reading device, a feeding device and an image forming apparatus according to the present invention is such that a sheet is formed with a predetermined charge. In the sheet conveying device for adhering, feeding, and conveying the sheet to the adsorption surface by using electrostatic force by bringing the sheet into contact with the adsorbed surface, a physical property value detecting unit for detecting a physical property value of the sheet to be fed, and an adsorption A charge forming unit that forms a charge on the surface, and a control unit that controls the amount of charge formed by the charge forming unit and the adsorption time, which is the time during which the sheet is in contact with the adsorption surface, are provided. It is characterized in that the charge amount and the adsorption time are controlled according to the physical property values.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION [First Embodiment] A first embodiment of a sheet conveying device, an automatic document reading device, a feeding device and an image forming apparatus according to the present invention will be described with reference to the drawings. FIG. 1 is a top view of the sheet conveying device according to the first embodiment, FIGS. 2 to 6 are sectional views of the sheet conveying device, showing a flow of suction, separation, and conveying operations, and FIG. 7 is a sheet conveying device. 10 is an electric block diagram showing the wiring path of the electric component, FIG. 8 is a diagram showing an operation sequence of the electric component in the sheet conveying device, FIG. 9 is a charging roller charging pattern diagram for charging the dielectric belt of the sheet conveying device, FIG. FIG. 11 is a sectional view of a sheet physical property value measuring unit in the sheet conveying apparatus, and FIG. 11 is a sectional view of an image forming apparatus equipped with the sheet conveying apparatus.

FIG. 11 shows an automatic document reading device 40 and a feeding device.
3 is a cross-sectional view of an image forming apparatus 42 equipped with 41. FIG. The document is fed and conveyed by the automatic document reader 40, and
Scanned by 43 and the platen belt 44
It is conveyed on the sheet 45 and discharged onto the discharge tray 46. Then, the image read by the document reading unit 43 is the photosensitive drum 47.
It is formed as a latent image on the upper side, and is imaged as a toner image by the developing unit 48. Transfer sheet P placed on the feeding device 41
Is transferred to the transfer / separation unit 50 via the transfer path 49. The toner image formed by the transfer / separation unit 50 is transferred to the transfer sheet P, and is discharged to the outside of the image forming apparatus 42 via the conveyance unit 51 and the fixing device 52.

Referring to FIG. 1, the structure of the suction belt unit 1 which is a sheet conveying device included in the automatic document reading device 40 and the feeding device 41 will be described. The suction belt unit 1 is shown in FIG.
Drive rollers 4 and driven rollers 5 made of metal such as SUS and grounded to GND are rotatably supported on the side plates 2 and 3 shown in FIG.

The drive roller 4 is adapted to be driven by a belt / roller drive motor 6 (see FIG. 7) via a belt clutch 16. Between the driving roller 4 and the driven roller 5, for example, the thickness is about 75 μm, and the volume resistivity is 1.0.
A dielectric belt 7, which is a PI seamless belt of × 10 ¹⁶ Ω · cm, is stretched.

As the dielectric belt 7, an elastomer having a thickness of about 300 μm and a volume resistivity of 1.0 × 10 ¹⁶ Ω · cm may be used. The driven roller 5 is provided with bushes 9 at both ends, and the bush 9 is configured to be movable in the biasing direction of the compression coil spring 8. Therefore, the driven roller 5 is biased to the dielectric belt 7 by pressing the bush 9 in the direction of arrow A with, for example, about 10 N by the compression coil spring 8. Then, the driving force is transmitted to the dielectric belt 7 by the frictional force acting between the drive roller 4 and the dielectric belt 7.

As shown in FIG. 2, when the dielectric belt 7 is charged, the dielectric belt 7 is sandwiched between the charging roller 10 as a charge forming means on the outer peripheral surface and the metal roller 11 on the inner peripheral surface. This is performed by applying an AC voltage from the AC power supply 12 to the charging roller 10. The high voltage waveform is an AC wave as shown in FIG. 9, for example, an AC wave output at Vpp = 8 kV and T2 = (cycle corresponding to a movement amount of the dielectric belt 7 of 3 mm). The surface of the charging roller 10 is made of conductive rubber of 1.0 × 10 ¹⁵ Ω · cm.

Further, so as to contact the dielectric belt 7,
The dielectric belt 7 has SUS for removing electric charges on the surface.
A static elimination needle 32 composed of a conductive wire material such as is disposed to eliminate static electricity from the dielectric belt 7 every one turn.

On the downstream side of the suction belt unit 1 in the sheet conveying direction, a conveying roller pair 13 having EPDM rubber or the like formed on its surface is arranged. As shown in FIG. 1, the conveying roller pair 13 is synchronously driven with the driving roller 4 by a timing pulley 14 and a timing belt 15.

On the side plates 17 and 18 of the suction belt unit 1,
A fan gear 19 is provided, and the fan gear 19 meshes with the gear 20. The gear 20 is fixed to the swing shaft 21,
21 is a stepping motor, and the drive is transmitted from a belt unit drive motor 22 (see FIG. 7). Therefore, the suction belt unit 1 is configured so that the belt unit drive motor 22 causes the swing shaft 21, the gear 20, the fan gear 19, and the side plates 17, 18 to drive together and swing.

As shown in FIG. 2, a surface electrometer 24, which is surrounded and supported by a holder 23 made of a non-conductive resin, is arranged inside the dielectric belt 7. Surface electrometer 24
Is supported so that the distance between the inner peripheral surface of the dielectric belt 7 and the surface electrometer is maintained at, for example, about 1 mm so that the potential on the inner peripheral surface of the dielectric belt 7 can be measured.

Below the suction belt unit 1, a sheet tray 25 on which a sheet bundle P is stacked is arranged. The sheet bundle P stacked on the sheet tray 25 is a tray lifting motor.
The drive of 26 (see FIG. 7) raises the link 27. A sheet height detection sensor 28 is arranged above the sheet tray 25 so that it can be detected when the upper surface of the sheet bundle reaches a predetermined height.

A physical property value measuring section 29 as a physical property value detecting means for measuring a physical property value of the sheet is arranged downstream of the front end position of the sheet tray 25 in the sheet conveying direction. The physical property value measurement unit 29 includes a pad 30 formed of EPDM rubber and a pad 30.
It is composed of a pad frame 31 which is a metal conductor and surrounds 30. The pad frame 31 is grounded to GND, and the pad 30
The upper surface height is set to be about 2 mm higher than the detection height of the paper surface height detection sensor 28.

Next, the operation of adsorbing, separating and conveying the sheet P will be described step by step with reference to the sequence chart of FIG.

In FIG. 2, first, the bias voltage described above is output from the AC power source 12 (a in FIG. 8), and alternating charges of about 3 mm pitch are formed on the dielectric belt 7. At the same time, by driving the belt and roller drive motor 6 (b in FIG. 8) and connecting the belt clutch 16 (c in FIG. 8),
The dielectric belt 7 is driven in the transport direction. When the dielectric belt 7 is rotated for a predetermined time and sufficient charge is formed on the dielectric belt 7, the belt clutch 16 (d in FIG. 8) and the AC power supply 12 (e in FIG. 8) are turned off.

Next, as shown in FIG. 3, the sheet tray 25
The sheet stack P stacked on the tray P is moved to the tray lifting motor 26 (see FIG. 9).
Drive (see f in FIG. 8). And
When the upper surface of the sheet bundle is detected by the sheet height detection sensor 28 (g in FIG. 8), the tray elevating motor 22 stops driving (h in FIG. 8).

Then, by rotating the belt unit drive motor 26 by a predetermined angle (i in FIG. 8), the suction belt unit 1 is swung to bring the dielectric belt 7 into contact with the upper surface of the sheet bundle P. Sheet bundle P in contact with the dielectric belt 7
The uppermost paper P1 of 1 is polarized by the charges formed on the dielectric belt.

An attraction force acts between the charges formed on the dielectric belt 7 and the polarized sheet bundle P, and the uppermost sheet P1 of the sheet bundle P is attracted onto the dielectric belt 7.

In this state, the belt clutch 16 is connected for a predetermined time (j in FIG. 8). The top sheet P1 of the sheet bundle P is a pad
A dielectric belt 7 is sandwiched between 30 and the driven roller 4 and sandwiched. Since pressure is applied to the uppermost sheet P1 by the pad 30, for example, two sheets from the sheet bundle P, even if they are adsorbed on the dielectric belt, a friction resistance acts on the lower sheet and only the sheet P1 is shown in FIG. Driven roller 4 and pad as shown
It is sandwiched between 30.

Next, by applying a predetermined DC bias to the driven roller 4, the physical property value of the sandwiched sheet P1 is measured (k in FIG. 8). As shown in the right side of FIG. 10, the measurement system includes a dielectric belt 7 having a charged electric resistance R1 and electrostatic capacity C1, a sheet P1 having an electric resistance R2 and electrostatic capacity C2, an electric resistance R3, and an electrostatic capacity. Pad with capacity C3
It can be regarded as a circuit in which 30 is connected in series.

As shown in FIG. 10, this measuring circuit is divided into a resistance measuring circuit 33 for measuring the electric resistance of the sheet P1 and a capacitance measuring circuit 34 for measuring the electrostatic capacitance of the sheet P1. Connected to circuit 35. Arithmetic circuit 35
Is a calculation means for calculating the electrostatic capacity and the electric resistance value, and is connected to a control circuit 36 which is a control means for controlling the amount of electric charge and the suction time during which the sheet is in contact with the suction surface.

Next, as shown in FIG. 5, the belt unit drive motor 22 is driven in the direction opposite to the previous direction (1 in FIG. 8) to swing the belt unit 1. Thereafter, the belt clutch 16 is connected (m in FIG. 8), the AC power source is turned on (n in FIG. 8), and the sheet P1 adsorbed on the dielectric belt 7
To transport.

As shown in FIG. 6, the conveyed sheet P1
Passes through the sheet detection sensor 37, and when the sheet detection sensor 37 catches the leading edge signal of the sheet P1 (o in FIG. 8), the belt clutch 16 is separated and engaged (p in FIG. 8), and the AC power supply 12 is turned off.
Set to F (q in FIG. 8). After that, after the sheet detection sensor 37 catches the trailing edge signal of the sheet P1 (r in FIG. 8), the belt / roller drive motor 6 is turned off (s in FIG. 8).

As shown in FIG. 7, the belt, roller drive motor 6, tray elevating motor 26, and belt unit drive motor 22 receive oscillation of a predetermined pulse output from a pulse oscillator 53 by a motor driver 54. Driven, CP
It is controlled by U55.

After the physical property values (electrostatic capacity, electric resistance) of the sheet P1 are detected by the above detection method, the adsorption failure of the sheet P1 on the dielectric belt 7 or the dielectric belt 7 is detected according to the physical property values.
Controls parameters that affect adsorption and separation that suppress double feed due to simultaneous adsorption of two sheets.

The parameters are mainly 1. 1. Amount of electric charge on the dielectric belt 7 (FIG. 9: Surface potential amount Vpp of the dielectric belt 7), 2. 2. The charge pitch on the dielectric belt 7 (FIG. 9: surface potential period T2 of the dielectric belt 7), 3.
There are three times from the time when the dielectric belt 7 is brought into contact with the sheet bundle P until the suction belt unit 1 is raised (FIG. 8: suction time T1).

As an example of the control, if it is judged that the sheet P1 to be fed is a thin paper based on the measured values (electrical resistance, electrostatic capacity) of the physical property value measuring section 29 shown in FIG. T1 is lengthened to about 1.5 s, for example. Then, the suction force of the sheet located under the sheet P1 to the dielectric belt is sufficiently attenuated, and then the suction belt unit 1 is raised to feed the sheet. When the present invention is used as the feeding device 41 shown in FIG. 11, the sheet P is often replenished with a paper pack (not shown) of the same paper type and size. Therefore the feeding device
In many cases, the uppermost sheet P1 and the lowermost sheet of the sheets stacked on 41 are of the same paper type and the same size. Therefore, if it is determined that the uppermost sheet P1 is a thin sheet, it is determined that the second and subsequent feedings are all thin sheets, and the control for advancing the sheet as shown in FIG. 4 is not performed. The electrification from the second sheet fed is the surface potential amount Vpp of the dielectric belt 7 and the surface potential cycle T of the dielectric belt 7.
2 is controlled to be small. As a result, the suction force applied to the sheet below the sucked sheet is also reduced, so that the suction time T2 is controlled to be shorter than the previously described 1.5 s.

On the contrary, if the physical property value measuring unit 29 determines that the first sheet P1 to be fed is thick paper, the feeding control is performed by shortening the adsorption time T1 to, for example, about 0.2 s. For feeding the second and subsequent sheets, Vpp and T2 are increased in order to further increase the suction force between the suction sheet P1 and the dielectric belt 7. The adsorption time T1 can be separated in about 0.2 seconds, which is the same as the previous time, because the weight of the sheet to be fed is heavy.

Similarly, for copy output paper and the like, the electric resistance and electrostatic capacity of the paper are measured to determine the paper type, environment, etc., and control is performed accordingly.

Further, as shown in FIG. 8, the surface potential meter 24 constantly monitors the surface potential of the surface of the dielectric belt 7. It is detected whether or not a desired potential is placed on the belt according to the magnitude of the potential amount (s in FIG. 8) or the attenuation rate of the potential amount (slope of s to t in FIG. 8). If the attenuation rate is large depending on the environment, the amount of potential generated from the AC power source (Fig. 9
Vpp) is increased. If the electric potential amount (s in FIG. 8) of the belt surface potential sensor is smaller than a predetermined value due to deterioration of durability or damage of the dielectric belt 7, the operation unit of the image forming apparatus 42 (which will be described later) equipped with this suction belt unit 1 ( A message notifying that the belt should be replaced is displayed in (not shown).

As described above, the amount of electric charge and the time are controlled according to the physical property values of the sheet, and thus the suction force acting between the first sheet P1 and the dielectric belt 7 and 2 are adjusted according to the sheet to be fed. By properly setting the suction force acting between the first sheet and the dielectric belt 7, it is possible to prevent defective feeding and double feeding regardless of whether the sheet to be fed is thin paper, thick paper, or copy output paper.

Since the suction time can be controlled according to the sheet to be fed, the feeding time per sheet can be shortened and the feeding speed can be increased. The productivity of the device is improved. Further, along with this, it can be used in a high-speed copying machine and the copy volume increases.

Further, by setting the voltage applied to the dielectric belt to an appropriate value capable of attracting the sheet, it is not necessary to apply extra power, and the power of the image forming apparatus 42 can be reduced.

Second Embodiment Next, a second embodiment of the sheet conveying device, the automatic document reading device, the feeding device and the image forming apparatus according to the present invention will be described with reference to the drawings. Figure 12-Figure
16 is a sectional view of the sheet conveying device according to the present embodiment,
FIG. 17 is a diagram showing a flow of suction, separation, and transport operations, FIG. 17 is an electrical block diagram showing wiring paths of electrical components in the sheet transport device, FIG. 18 is a diagram showing an operation sequence of electrical components in the sheet transport device, and FIG. It is a detailed view of a physical property value detection unit of the sheet.

This embodiment differs from the first embodiment in the position of the physical property value measuring section and the feeding operation of the sheet conveying device. The operation of sucking, separating, and transporting the sheet P will be described step by step with reference to the sequence chart of FIG.

First, as in the first embodiment, the dielectric belt 7 is charged in the state shown in FIG. 12 (a in FIG.
e) Next, as shown in FIG. 13, the suction belt unit 1 is lowered (i in FIG. 18) and is brought into contact with the upper surface of the sheet bundle P for a predetermined time (T1) to suck the uppermost sheet P1 of the sheet bundle P. . Then, as shown in FIG. 14, the suction belt unit 1 is raised (k in FIG. 18) to separate the uppermost sheet P1.

Next, as shown in FIG. 15, the belt clutch 16 is connected (1 in FIG. 18), and the sheet P1 attracted to the dielectric belt 7 is conveyed. Up to this point, the control is the same as in the first embodiment. However, unlike the first embodiment, the physical property value of the sheet has not been detected yet, and therefore the first feeding sheet is controlled at the adsorption time T1 that is determined in advance.

As shown in FIG. 15, when the front end of the sheet P1 reaches the physical property value measuring section 60 and the sheet detection sensor 37 detects the front end of the paper (n in FIG. 18), the belt and roller drive motor 6 are stopped ( 18 a). The sheet P1 is stopped while being sandwiched by the physical property value measuring unit 60, and in this state, the sheet P1 is
The physical property value of is detected.

As shown in FIG. 19, the metallic disk 62 attached to the control tube 61a of the solenoid 61 rises when a voltage is applied to the solenoid 61 (a in FIG. 18). As a result, the sheet P1 is sandwiched between the disc 62 and the sensor lever 63 with a predetermined pressure. The sensor lever 63 is made of a conductive metal and is provided with an urging means (not shown) for urging the sheet P1 toward the disc 62.

The disk 62 is connected to the GND, and the physical value of the sheet is detected by applying a predetermined voltage V to the sensor lever 63 (c in FIG. 18). The sensor lever 63 is connected to the resistance value measuring circuit 33 and the electrostatic capacity measuring circuit 34 via a switch circuit 64, and the resistance value and the electrostatic capacity of the sheet P1 can be measured by switching the switch circuit 64. The detected physical property value of the sheet is transferred to the arithmetic circuit 35, subjected to arithmetic processing, and then transferred to the control circuit 36. The feeding operation from the second sheet is controlled by the physical property value of this sheet. The parameters and method to be controlled are the same as those in the first embodiment, and detailed description thereof will be omitted.

The electric circuit shown in the lower part of FIG. 19 is a sheet P1.
It is a model figure of the physical-property value of. The sheet P1 has an electric resistance R
It can be regarded as a parallel circuit of a resistor 65 having a capacitance of 65 and a capacitor 66 having a capacitance of C.

After detecting the physical properties of the sheet, the solenoid
The voltage of 61 is turned off (D in FIG. 18) to avoid the disk 62. Then, the belt and roller drive motors are operated again (e in FIG. 18) to convey the sheet P1 (FIG. 16).

As described above, similarly to the first embodiment, the charge amount and the time are controlled according to the physical property values of the sheet, and the first sheet P1 and the dielectric material are adjusted according to the sheet to be fed. By properly setting the attraction force acting between the belts 7 and the attraction force acting between the second sheet and the dielectric belt 7, regardless of whether the sheet to be fed is thin paper, thick paper or copy output paper, feeding failure, Double feeding can be prevented.

Since the suction time can be controlled according to the sheet to be fed, the feeding time per sheet can be shortened and the feeding speed can be increased. The productivity of the device is improved. Further, along with this, it can be used in a high-speed copying machine and the copy volume increases.

Further, by setting the voltage applied to the dielectric belt to an appropriate value capable of attracting the sheet, it is not necessary to apply extra power, and the power of the image forming apparatus 42 can be reduced.

[0058]

As described above, by feeding the sheet while detecting the physical property value of the sheet to be fed, it is possible to provide a feeding device having excellent feeding stability.

Further, depending on the physical property value of the sheet to be fed,
By changing the suction time and feeding, the productivity of the feeding and image forming apparatus can be improved.

Further, by setting the voltage applied to the dielectric belt to an appropriate value capable of attracting the sheet, it is not necessary to apply extra power, and the power of the image forming apparatus can be reduced.

[Brief description of drawings]

FIG. 1 is a top view of a sheet conveying device according to a first embodiment.

FIG. 2 is a cross-sectional view of a sheet conveying device, which illustrates suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 3 is a cross-sectional view of the sheet conveying device, which illustrates suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 4 is a cross-sectional view of the sheet conveying device, which illustrates suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 5 is a cross-sectional view of the sheet conveying device, showing suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 6 is a cross-sectional view of the sheet conveying device, showing suction, separation,
It is a figure which shows the flow of a conveyance operation.

FIG. 7 is an electric block diagram showing a wiring path of electric parts of the sheet conveying apparatus.

FIG. 8 is a diagram showing an operation sequence of electric parts in the sheet conveying apparatus.

FIG. 9 is a charging roller charging pattern diagram for charging the dielectric belt of the sheet conveying device.

FIG. 10 is a cross-sectional view of a sheet physical property value measurement unit in the sheet conveyance device.

FIG. 11 is a cross-sectional view of an image forming apparatus including a sheet conveying device.

FIG. 12 is a cross-sectional view of the sheet transporting device according to the second embodiment, showing a flow of suction, separation, and transport operations.

FIG. 13 is a cross-sectional view of the sheet conveying device, which illustrates suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 14 is a cross-sectional view of the sheet conveying device, which illustrates suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 15 is a cross-sectional view of the sheet conveying device, including suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 16 is a cross-sectional view of the sheet conveying device, including suction, separation, and
It is a figure which shows the flow of a conveyance operation.

FIG. 17 is an electric block diagram showing a wiring path of electric parts in the sheet conveying apparatus.

FIG. 18 is a diagram showing an operation sequence of electric components in the sheet conveying apparatus.

FIG. 19 is a detailed diagram of a sheet physical property value detection unit.

FIG. 20 is a diagram theoretically simulating the attenuation of the attraction force of a second sheet of thick paper attracted to a dielectric belt in a conventional electrostatic attraction type feeder.

FIG. 21 is a diagram theoretically simulating the attenuation of the attraction force of a second sheet of thin paper attracted to a dielectric belt in a conventional electrostatic attraction type feeder.

[Explanation of symbols]

C1, C2, C3 ... Capacitance P: Sheet bundle P1 ... Top paper R1, R2, R3 ... Electric resistance 1 ... Suction belt unit 2, 3 ... Side plate 4 ... Drive roller 5 ... driven roller 6 ... Belt and roller drive motor 7 ... Dielectric belt 8 ... Compression coil spring 9 ... Bush 10 ... Charging roller 11… Metal roller 12… AC power supply 13… Conveyor roller pair 14… Timing pulley 15… Timing belt 16… Belt clutch 17, 18… Side plate 19 ... fan gear 20 ... Gear 21 ... Swing axis 22… Belt unit drive motor 23… Holder 24… Surface electrometer 25… Sheet tray 26… Tray lifting motor 27… Link 28… Detection sensor 29… Physical property measurement unit 30… Pad 31… Pad frame 32… Static elimination needle 33… Resistance measurement circuit 34… Capacitance measurement circuit 35… Arithmetic circuit 36 ... Control circuit 37… Sheet detection sensor 40… Automatic manuscript reader 41… Feeding device 42 ... Image forming device 43… Original scanning section 44… Platen belt 45… Platen 46… Ejection tray 47 ... Photosensitive drum 48 ... Developer 49… Transport path 50… Transfer, separation section 51… Conveyor 52… Fixing device 53 ... Pulse oscillator 54… Motor driver 55… CPU 60… Physical property measurement unit 61 ... Solenoid 61a ... Control tube 62… Disc 63… Sensor lever 64… Switch circuit 65… resistance 66… Condenser

Claims (8)

[Claims] 1. A sheet conveying device for adsorbing, feeding, and conveying a sheet on an adsorption surface by using electrostatic force by bringing the sheet into contact with the adsorption surface on which a predetermined electric charge is formed. A physical property value detecting means for detecting a physical property value; a charge forming means for forming an electric charge on the adsorption surface; and a control means for controlling an amount of electric charge formed by the charge forming means and an adsorption time for which the sheet is in contact with the adsorption surface. The sheet conveying apparatus, wherein the control means controls the amount of electric charge and the adsorption time according to the physical property value of the sheet. 2. The charge is an alternating charge in which positive and negative charges are alternately placed, and the control means controls the positive and negative charge amounts according to the physical property value of the sheet, and the length between the positive and negative charges. The sheet conveying device according to claim 1, wherein the suction time during which the sheet is in contact with the suction surface is controlled. 3. The physical property value of the sheet is the electrostatic capacitance and electric resistance value of the sheet, and the control means is positive in accordance with the numerical value arithmetically processed by the arithmetic means for arithmetically processing the electrostatic capacitance and electric resistance value. 3. The sheet conveying apparatus according to claim 1, wherein the amount of each negative charge, the length between positive and negative charges, and the suction time during which the sheet is in contact with the suction surface are controlled. 4. An elastic body is interposed in the physical property value detecting means, and the sheet is separated from the sheet bundle by using the frictional force of the elastic body to measure the physical property value of the sheet. 4. The sheet conveying device and automatic document reading device according to items 1 to 3. 5. The sheet conveying apparatus according to claim 1, wherein the physical property value detecting means also serves as a sheet detecting means for detecting the conveyance of the sheet. 6. An automatic document reading device comprising the sheet conveying device according to any one of claims 1 to 5. 7. A sheet feeding device comprising the sheet conveying device according to claim 1. 8. A sheet conveying apparatus according to claim 1, an automatic document reading apparatus according to claim 6, and at least one of a feeding apparatus according to claim 7. Image forming apparatus.