JPH10271850A - Medium carrying device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a medium carrying device, the carrying characteristic of which is reduced in changes over aging and which can highly stably transport a medium even under a high-humidity condition, by covering the belt-like electrode forming surface of the base material of a stator composed of a fluoroplastic with an insulating layer so that belt-like electrodes may not be exposed. SOLUTION: A medium carrying device is composed of a platy stator 1 and a platy mover 2 and carries the mover 2 together with a medium 3, by utilizing the carrying force applied to the mover 2 from the stator 1 by placing the mover 2 on the stator 1 and the medium 3 on the mover 2. The stator 1 is provided with a plurality of belt-like electrodes 12 arranged in parallel with each other on a base material 11 and an insulating layer 13 covering the electrodes 12. Since the surface of the base material 11 of the stator 1 made of a fluoroplastic material is coated with the insulating layer 13 made of a fluroplastic or silicon resin, the changes, of the carrying characteristic of the carrying device over aging becomes extremely small, and the carrying stability of the device is extensively improved even under a high humid condition.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a copying machine, a printer, a facsimile, an automatic cash dispenser, and the like, and is used for media such as paper sheets and bills, and cards such as cash cards and prepaid cards. The present invention relates to a medium conveying device for conveying, and particularly to a medium conveying device using electrostatic force.

[0002]

2. Description of the Related Art Conventionally, copiers, printers, facsimile machines, automatic cash dispensers and the like have been disclosed in Japanese Unexamined Patent Publication No. 5-27068.
As disclosed in Japanese Unexamined Patent Publication No. 1 (1993), there has been used a transfer device that presses a rubber roller driven by a rotary electromagnetic motor against a medium such as paper sheets. However, in such a transfer device, heat generation and large power consumption of the motor itself become problems, and there is a limit to downsizing due to the configuration using the electromagnetic motor and the rubber roller. In addition, since the frictional force between the rubber roller and the transport medium is used as the force used for transporting the medium, the rubber roller itself or the rubber roller and the medium are used to obtain a stable transport force due to wear of rubber, adhesion of paper powder, and the like. It was necessary to periodically inspect and repair the pressure contact force.

In order to solve these problems, Japanese Patent Laid-Open Publication No.
There is a transfer device using an electrostatic force disclosed in 19602 and JP-A-6-56290. Such a transport device includes a stator having strip electrodes and a movable element having a resistance layer. In Japanese Patent Application Laid-Open No. Hei 5-319602, a paper to be conveyed is directly used as a moving element. In Japanese Patent Application Laid-Open No. 6-56290, a conveyed object such as paper is placed on a moving element having a high resistance value. In both cases, the electrodes of the stator are divided into three systems (three phases), which are sequentially arranged at equal intervals. For an overview of the operating principle, see
-285978 and the above-mentioned JP-A-5-3196.
As disclosed in Japanese Unexamined Patent Application Publication No. 02-206 and Japanese Unexamined Patent Application Publication No. Hei 6-56290, by applying a special combination of voltages to each phase of the stator electrode immediately before transport, positive and negative currents existing in the resistance layer of the mover can be obtained. Is electrostatically polarized. Hereinafter, this operation is referred to as an initial polarization step. When electrostatic polarization is sufficiently advanced in the movable element, when the voltage is applied to each phase of the stator electrode while switching the combination of the voltage patterns for transport, the movable element is transported by repulsion and attraction of electric charges.

[0004] However, the transfer device utilizing the electrostatic force as described above has a problem that the transfer of the moving element becomes unstable in a high humidity environment. It is considered that this is because in a high humidity environment, the movable element and the stator are in a state of being easily adsorbed. For this reason, as a stabilization measure, Japanese Patent Laid-Open No.
Japanese Patent No. 91984 discloses a technique in which a hole is formed in a stator and air is blown out from the hole toward the moving element to prevent the moving element and the stator from sticking together for the purpose of suction removal of the moving element and the stator. I have.

In Japanese Patent Laid-Open Publication No. Hei 5-22959,
For the same purpose, there has been disclosed a technique in which a surface of a moving element or a stator is provided with irregularities to roughen a surface where the moving element and the stator come into contact, or a hole is formed in the moving element.

[0006]

However, in the method of blowing air by making holes in the stator, the number of blower pipes increases in proportion to the extension of the transport path, and the blower and external power for air compression are increased. The cost including installation is greatly increased, and at the same time, the size of the transfer device is increased. Therefore, it is difficult to differentiate the transfer device from a transfer path using a conventional electromagnetic motor. Further, if the distance between the moving element and the stator is too large, the conveyance stability is reduced. Therefore, the distance between the moving element and the stator needs to be always kept constant. For this purpose, it is necessary to control the flow rate, pressure, and the like of the air for blowing, and a control circuit, a flow rate sensor, a distance sensor, and the like are added, so that the cost increases and the product is not practical.

Also, a method of providing irregularities on the surface of the moving element or the stator is to mix the spacer material such as glass beads into the adhesive and apply it to the moving element or the stator. The degree of dispersion in the adhesive is an important factor, and the uniformity of the irregularities changes significantly. As a result, in order to obtain transport stability over the entire surface of the stator, it is necessary to uniformly control the mixing ratio and the degree of dispersion of the spacer material described above. High precision is required, accompanied by a significant increase in cost. When such a spacer material and an adhesive are applied to the moving element,
Because the weight of the mover is significantly increased, the maximum weight of the medium that can be conveyed is reduced. Even if the technique disclosed in Japanese Patent Application Laid-Open No. 5-22959 was used, stable operation could not be obtained in a high-humidity environment, and the transport characteristics deteriorated with a significant change with time.

[0008]

In order to solve the above-mentioned problems, the present invention provides a stator having a plurality of strip electrodes arranged in parallel on an insulating base material and provided with an insulating layer covering the strip electrodes. And a medium for transporting the movable element by using an electrostatic force generated between the stator and the movable element by switching a polarity of a voltage applied to the strip electrode in a predetermined pattern. In the transfer device, the base material is made of a fluorine-based resin material, and the insulating layer is made of a fluorine-based resin material. The insulating layer covers at least a band-shaped electrode forming surface of the base material so that the band-shaped electrode is not exposed. It was decided that.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a block diagram showing an example of an embodiment of a medium conveying device according to the present invention. FIG. 1 (a) is an overall perspective view, and FIG. 1 (b) is a side view of a stator. FIG. 2 is a combination of block diagrams of a driving mechanism. The medium transporting apparatus according to the present embodiment includes a plate-like stator 1 and a moving member 2, the moving member 2 is mounted on the stator 1, and the medium 3 is mounted on the moving member 2.
Is carried, and the moving element 2 and the medium 3 are conveyed together by the conveying force acting on the moving element 2 from the stator 1.

The stator 1 has a plurality of strip electrodes 12 arranged in parallel on a base material 11 at predetermined intervals, and an insulating layer 13
Is provided. Hereinafter, the surface where the movable element 2 and the stator 1 are in contact is referred to as a sliding surface. The base material 11 is an insulator using a fluororesin. As an example of a fluororesin, PT
There are FE, FEP, ETFE, PFA, PCTFE and the like. In this embodiment, PTFE having high resistance, low moisture absorption, and low dielectric constant is used.

Here, glass fibers may be mixed into the fluororesin material constituting the base material 11. By mixing glass fibers, it is possible to prevent the substrate 11 from bending. The shape and thickness of the base material 11 can be freely designed, but when PTFE is used as the base material 11,
Since PTFE has a strong non-adhesive property, it may not be possible to form the strip electrode 12 and the insulating layer 13 thereon as it is. In such a case, the adhesion can be improved by a known surface modification technique such as a chemical treatment with a liquid ammonia solution of metallic Na or a discharge treatment in NH ₃ .

The strip electrode 12 can be made of any conductive material such as gold or copper, and can be formed on the substrate 11 by a known technique such as printing or etching. The strip-shaped electrode 12 is divided and connected into three phases.
Phase, called the C phase, the strip-shaped electrode connected to the A phase is 12A,
The strip electrodes connected to the B phase are indicated as 12B, and the strip electrodes connected to the C phase are indicated as 12C. The width and electrode pitch of the strip electrode 12 can be freely set. For example, the electrode pitch can be set to 0.2 mm, 0.4 mm, 1.0 mm, and the like, and the electrode width can be set to 0.1 mm, 0.2 mm, 0.3 mm, and the like. In the present embodiment, the electrode pitch is 0.4 mm,
Take a stator with an electrode width of 0.1 mm as an example.

The insulating layer 13 is made of a fluorine-based paint or a silicon-based paint to prevent the strip-shaped electrode 12 from being exposed, mainly for the purpose of interlayer insulation of the strip-shaped electrode 12, moisture proofing, and reduction of current consumption. The surface on which the strip electrode 12 is formed is coated. The thickness of the insulating layer 13 is arbitrary, but if the thickness is excessively large, the conveying force is weakened. If the thickness is too small, air discharge occurs. In the present embodiment, coating was performed at a thickness of about 80 μm.

In FIG. 1, the insulating layer 13 is provided only on the surface of the substrate 1 on which the strip electrodes 12 are formed. However, the insulating layer 13 may be provided so as to cover the entire surface of the substrate 11. The base of the mover 2 is, for example, PET, polyimide (PI), polycarbonate, polyamide, glass fiber, or the like. In this embodiment, a 25 μm-thick PET whose surface resistance on the surface on which the medium 3 is placed is adjusted to 10 ¹¹ to 10 ¹⁵ [Ω / □] is used. As a method of adjusting the surface resistance, a method of applying an antistatic agent having a weak antistatic effect or the like can be used. In addition to this, similarly to the stator, a flexible printed circuit board having electrodes therein can be used as the moving element 2.

The power supply 5 is a voltage source for applying a voltage to the strip electrode 12, and supplies a positive voltage and a negative voltage to the drive circuit 6. The drive circuit 6 can freely switch positive and negative voltages and 0 [V] (ground potential) to each of the A-phase, B-phase and C-phase of the strip-shaped electrode 12, respectively.
The polarity of the voltage applied to each phase is changed by a control signal from the control circuit 7. The drive circuit 6 includes a control circuit 7
The voltage value to be applied can be changed according to the signal from.

Hereinafter, in the present embodiment, the voltage polarity applied to each phase is represented as [A-phase polarity, B-phase polarity, C-phase polarity]. The positive polarity is represented by P, the negative polarity by N, and the ground potential by G. For example, when applying a positive polarity voltage to the A phase, a negative polarity voltage to the B phase, and a negative polarity voltage to the C phase, [P, N,
N]. The operation will be described below.

The medium transport device utilizing the electrostatic force polarizes the electric charge in the moving element 2 into a predetermined pattern, and repulses and attracts the polarity of the polarized electric charge and the polarity of the voltage applied to the strip electrode 12. Use Here, an initial polarization step of pre-polarizing the charges in the moving element 2 to be transported is required. The pattern of the voltage applied to the strip electrode 12 during the initial polarization step is called an initial polarization pattern, and the voltage pattern applied to the strip electrode 12 during transport is called a transport pattern.

FIG. 2 is an explanatory view showing the principle of movement of the moving element in the present embodiment. When the moving element 2 on which the medium 3 has arrived reaches the transport start position, under the control of the control circuit 7, the driving circuit 6 outputs an initial polarization pattern, for example, [N,
P, P] is applied to each phase of the strip electrode 12. When [N, P, P] is applied to each phase of the strip electrode 12, due to the influence of the electric charge charged in the electrode, as shown in FIG. Charges of opposite polarity accumulate. When sufficient charges are accumulated in the initial polarization pattern in the movable element 2, as shown in FIG. 2 (2), the voltage applied to the strip electrode 12 is the first stage pattern of the transport pattern [P, N, G]. , The same polarity repels and the opposite polarity attracts between the polarity of the voltage applied to the strip electrode 12 of each phase and the polarity of the electric charge polarized in the moving element 2. Due to the repulsion and attraction of the electric charges in the strip-shaped electrode 12 on the stator 1 side and the electric charges in the movable element 2, the movable element 2 and the medium 3 placed thereon start moving in the direction shown by the arrow.

When the moving element 2 moves by one pitch of the band-shaped electrode 12, the force in the conveying direction is weakened and the downward suction force is increased, and at the same time, the frictional force between the moving element 2 and the stator 1 is significantly increased. The mover 2 stops to move up. next,
As shown in FIG. 2C, the voltage applied to the strip electrode 12 is the second stage pattern of the transport pattern [G, P,
N], the moving element 2 is moved by one pitch of the electrode in the direction of the arrow and stopped by the same operation as described above. Further, although not shown, when the voltage applied to the strip-shaped electrode 12 is switched to the third stage pattern [N, G, P] of the transport pattern, the moving element 2 moves the electrode 1 pitch in the direction of the arrow by the same operation as described above. Move a minute and stop. Thereafter, the moving element 2 moves in the direction indicated by the arrow in FIG. 2 by one pitch of the strip electrode 12 by sequentially and repeatedly applying the first to third steps of the transport pattern. If the switching frequency of the three stages of the transport pattern is called a driving frequency, the moving speed of the movable element 2 can be controlled by changing the driving frequency. Speed is improved.

As described above, the stator 1 according to the present embodiment in which the base material 11 is made of a fluorine-based resin material and the insulating layer 13 is made of a fluorine-based resin material or a silicon-based resin material.
The time-dependent change in the transport characteristics of a conventional and a stator in which a general glass epoxy base material was coated with a resist as in the past was measured in a normal atmosphere. Here, variables such as the electrode pitch were the same.

The index of the characteristic evaluation is the arrival rate. The arrival rate is obtained by dividing an actual moving distance by a distance to be originally moved and displaying the ratio. When the moving element moves the distance as instructed, the arrival rate is 100%. Conversely, when the moving element does not operate at all, the arrival rate is 0%. When the above-mentioned stators were left standing for two days in a high-humidity environment of 40 ° C. and 90%, the arrival rate was measured. Then, 9
The arrival rate of 9 to 100% was obtained, and the change with time of the transport characteristics was remarkably improved.

Next, the transport characteristics in a high humidity environment were evaluated. As a result, the conventional stator has an absolute water content of 0.
015-0.020 (75-98% at 25 ° C. relative humidity)
At the time when the water content reaches 0% to 20%, whereas the stator 1 of the present embodiment has an absolute water content of 0.053 (corresponding to about 45 ° C. and 80%). Even under the conditions, a reaching rate of 98 to 100% was obtained.

The medium transporting device utilizing electrostatic force is easily affected by moisture. However, by forming the stator 1 from a resin material having low hygroscopicity and high water repellency as in the present embodiment, It is possible to obtain a medium transfer device in which the change in transfer characteristics with time is very small and is less affected by environmental humidity. Further, since the strip-shaped electrode 12 on the stator 1 forms a capacitor between adjacent electrodes, a large instantaneous current flows every time the applied voltage pattern is switched. However, the time during which the large current flows is extremely short, and the resistance between the electrodes is extremely high constantly, so that almost no current is consumed. Therefore, it can be said that the medium conveyance device using the electrostatic force consumes the current only when the applied voltage pattern changes, so that the more frequently the applied voltage pattern is switched,
Power consumption increases. The switching speed of the applied voltage pattern can be expressed as a drive frequency ω [Hz]. Further, the current consumption depends on the impedance Z of the stator 1.
The impedance Z is a function of the frequency ω and is used in a manner similar to “electrical resistance”. Ohm's law I = V /
When the applied voltage V is constant due to Z (ω), the current consumption I
Is inversely proportional to the impedance Z (ω). This current flows between adjacent strip-shaped electrodes 12 due to a potential difference on the stator 1. FIG. 3 is an explanatory view showing a capacitor model taking adjacent strip electrodes 12A and 12B as an example. When the resistance value R between the electrodes is extremely large, an electric circuit model approximation is taken taking neighboring strip electrodes 12A and 12B as an example. Then, the result is as shown in FIG.

The capacitance C of the capacitor is expressed by the following equation (1) using the electrode area S, the inter-electrode distance d, the relative permittivity of the stator ε, and the permittivity of vacuum ε ₀ .

[0025]

C = ε ₀ εS / d (1) The impedance Z (ω) is expressed by the following equation (2).

[0026]

## EQU2 ## Z (ω) = 1 / Cω (2) The impedance Z (ω) decreases as the driving frequency ω increases, so that more current is consumed during high-frequency driving. However, since the impedance Z increases as the capacitor capacitance C decreases, the current consumption I decreases according to Ohm's law described above. Capacitor capacity C
Is proportional to the relative dielectric constant of the stator, so that the current consumption is reduced when the stator is formed using a material having a small dielectric constant.
In the conventional stator, the dielectric constant of the glass epoxy used for the base material and the solder register used for the insulating layer is generally in the range of about 4 to 7. On the other hand, in the case of the stator 1 according to the present embodiment, the dielectric constant of the fluororesin used for the base material and the fluororesin or silicon resin used for the insulating layer is in the range of about 2 to 4. Thereby, the stator 1 of the present embodiment
Can reduce current consumption as compared with the conventional stator.

According to the medium transport device of the embodiment described above, the base material 11 of the stator 1 is made of a fluororesin material,
By coating the surface with a fluorine resin or a silicon resin, the change over time in the transport characteristics is extremely small, and the transport stability is significantly improved even in a high humidity environment. The stator 1 of the present embodiment can be easily manufactured by using a known electronic circuit board manufacturing technology, and requires no special device or special technology, so that there is no increase in cost due to technical development.

For this reason, it is not necessary to disperse a special spacer in a resin at a highly controlled weight ratio and with high precision as in the conventional case, and to coat it on the stator with high uniformity. Also, there is no need for a complicated control unit such as air pressure control or air flow control, and further, a large number of detection devices such as a position detection sensor and a flow sensor are not required. Therefore, the medium conveyance device of the present embodiment has a very small increase in cost regardless of the length of the conveyance path, and does not affect the product competitiveness at all.

In addition, fluororesins and silicone resins have extremely low moisture absorption and are excellent in moisture-proof properties.
The effect on the transport characteristics due to moisture absorption can be greatly delayed. Further, by configuring the stator 1 using a material having a low dielectric constant such as a fluororesin or a silicon resin,
Since the required current during high-frequency driving is reduced, power consumption during driving is reduced. Due to the reduction in power consumption, the capacity of the high-voltage power supply to be used can be reduced, so that not only the size of the device can be reduced, but also the cost of the device. When the power consumption is the same, the use of the stator 1 of the present embodiment enables driving at a higher frequency. Since the drive frequency is proportional to the transport speed, the maximum transport speed can be improved by increasing the maximum drive frequency.

In the present embodiment, a substrate-like linear transfer device has been described as an example. However, since the fluororesin and the silicon resin have high flexibility, the stator 1 can be manufactured from a flexible substrate. Therefore, a curved conveyance path having a curved portion can be configured. Further, in the present embodiment, the moving element 2 having a predetermined resistance value is used, but if the resistance value of the medium 3 to be conveyed is sufficiently high, the moving element is not used, and It is also possible to carry the medium 3 directly.

Further, the moving element 2 may have a structure in which an electrode is provided inside similarly to the stator 1 and an initial polarization state is created by applying a voltage to this voltage.
Further, the insulating layer 13 may be provided so as to cover not only the side of the base 11 on which the strip-shaped electrode 12 is formed, but also the entire surface of the base 11.
In this case, a higher moisture-proof effect can be obtained.

[0032]

As described above, according to the present invention, in a medium transporting apparatus utilizing electrostatic force, a fluororesin material is used for a base of a stator, and a fluororesin or By providing the insulating layer coated with the silicone resin, a change with time in the transport characteristics is extremely small, and high transport stability can be obtained even in a high humidity environment.

[Brief description of the drawings]

FIG. 1 is a configuration diagram illustrating an example of an embodiment of a medium conveyance device according to the present invention.

FIG. 2 is an explanatory view showing a moving principle of a moving element.

FIG. 3 is an explanatory diagram showing a capacitor model.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Stator 2 Moving element 12 Strip electrode 13 Insulating layer

Claims (6)

[Claims] 1. A plurality of strip-shaped electrodes are arranged in parallel on an insulating base material, a moving element is mounted on a stator provided with an insulating layer covering the strip-shaped electrodes, and a voltage polarity applied to the strip-shaped electrodes is determined. By switching in a given pattern, utilizing a static force generated between the stator and the movable element, in a medium transport apparatus that transports the movable element, the base material is made of a fluororesin material, A medium transport device, wherein the insulating layer is made of a fluorine-based resin material, and the insulating layer covers at least a surface of the base material on which the strip-shaped electrode is formed so that the strip-shaped electrode is not exposed. 2. The medium transport device according to claim 1, wherein the insulating layer is made of a silicon-based resin material. 3. The medium transport device according to claim 1, wherein the fluororesin material forming the base material and the insulating layer comprises:
A medium transport device comprising a material having a relative dielectric constant of 4 or less. 4. The medium transporting device according to claim 2, wherein the fluorine-based resin material forming the base material and the silicon-based resin material forming the insulating layer are materials having a relative dielectric constant of 4 or less. Media transport device. 5. The medium transporting device according to claim 1, wherein glass fibers are mixed into the fluorine-based resin material forming the base material. 6. The medium transport device according to claim 1, wherein a medium to be transported is used as the movable element, and the medium is transported by utilizing an electrostatic force generated between the stator and the medium. A medium transport device characterized by direct transport.