JPH04102002A - Paper sheet thickness detector - Google Patents

Abstract

PURPOSE:To make it possible to detect thickness of paper sheets with a high sensitivity by tightly inserting a paper sheet between a grounded potential surface and a detecting electrode and pressing the sheet by a pressing mean. CONSTITUTION:When a paper sheet 1 transferred is going into the gap between a roller 30 and an electrode plate 9, the roller 9, acting against the force of a spring 34, rotates by an amount corresponding to the thickness of the paper sheet 1 clockwise around its rotation axis 33 to tightly catch the paper sheet 1 between the roller and the electrode plate 9. When the paper sheet is caught between the roller 30 and the electrode plate 9, the electrode plate 9 detects a change of the electrostatic capacity corresponding to the change of permittivity which is determined by the thickness and material properties of the paper sheet 1. Therefore, if paper sheets have the same material properties, the permittivity changes according to the changes of the sheet thickness, and such changes of the thickness are detected as the changes of the electrostatic capacity by the electrode plate 9.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a paper sheet thickness detection device for detecting the thickness of paper sheets such as banknotes and copy paper.

(Prior Art) A device using a potentiometer is widely used as a thickness detecting device for a sheet of paper such as cloth or paper.As shown in FIG. Passing route 2
It is constructed by arranging a potentiometer 3 on top. This potentiometer 3 has an arm 5 attached to the rotating shaft 4.
, a roller 6 is rotatably attached to the tip of the arm, and a spring 7 is used to keep the roller 6 on the path 2 through which it always passes.
The force is applied to the lower surface side of the . In the state shown in FIG. 12, when the paper sheet 1 moves in the direction of the arrow and comes under the roller 6, the roller 6 rides on the paper sheet 1, causing the arm 5 to rotate clockwise. The rotation of the arm 5 is transmitted to the rotating shaft 4, and an output voltage proportional to the amount of rotation of the arm 5, that is, the thickness of the paper sheet 1, is output as a thickness detection signal of the paper sheet 1, as shown in FIG. It will be done.

[Problem to be solved by the invention]

However, in the method of detecting the thickness of the paper sheet 1 using the potentiometer 3, the amount of rotation of the arm 5 corresponding to the thickness of the paper sheet 1 is very small, and therefore the output voltage level from the potentiometer 3 is also very small. (There was an inconvenience that the thickness of the paper sheet 1 such as thin paper could not be detected with high accuracy.

In addition, when the paper sheet 1 is being conveyed at high speed, when the roller 6 rides on the paper sheet 1, an extra movement occurs due to the reaction, and as shown in FIG. 13, the output voltage waveform changes. There is an inconvenience that overshoe P appears.

In order to prevent such an overshoe P from occurring, it is necessary to make the biasing force of the spring 7 very strong, and in this case, the roller 6 will come into strong contact with the stage 2, which will cause the paper sheet 1 to be transported in the conveyance system. This causes a problem in that it becomes a load and the power consumption of the transport system increases.

Furthermore, in order to accurately detect the thickness using this type of potentiometer 3, it is necessary to attach the roller 6 to the stage 2 in the X direction, which is the running direction of the paper sheet 1, and in the Y direction, which is perpendicular to the traveling direction on the plane. The assembly was extremely difficult, as it had to be assembled with high precision to avoid even the slightest inclination in the upper and lower directions.

Furthermore, for example, when transporting banknotes one by one, 2
When detecting the overlapping state based on paper thickness, it is necessary to arrange a plurality of rollers 6 closely in the width direction of the paper sheet 1 to detect the thickness of the paper sheet 1 over the entire width. However, as is well known, since the potentiometer 3 has a large dimension in the width direction, it is inconvenient that the rollers 6 cannot be arranged in the width direction of the paper sheet 1 with high density.

The present invention has been made to solve the above-mentioned conventional problems, and its purpose is to provide an electrostatic detection device that can effectively solve the various problems caused by the conventional potentiometers. .

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention includes an oscillation circuit and a resonator separate and independent from the oscillation circuit, changes a tuning point in response to a change in external capacitance, and outputs a detection signal corresponding to the change in the tuning point. The passage path of the sheet of paper includes a ground potential plane at a position sandwiching the sheet of paper, and a detection circuit that detects and supplies changes in capacitance to a resonator of the tuned circuit. electrodes are arranged to face each other, and at least one side of the ground potential surface and the detection electrode is pressed against the other side directly or indirectly through an intermediary member to sandwich the paper sheet without a gap. The structure is characterized in that a pressing means is provided.

[Effect]

In the above configuration, when the paper sheet is conveyed along the passage path and enters between the detection electrode and the ground potential surface, the pressing means is provided on at least one side of the ground potential surface and the detection electrode. Therefore, the paper sheet is sandwiched between the ground potential surface and the detection electrode without any gap by the pressing force of the pressing means. At this time, an electric field is generated from the detection electrode toward the ground potential plane by driving the electrostatic sensor circuit, and the paper sheet passes through the electric field. The dielectric constant of the path section of this electric field changes depending on the thickness of the paper sheet sandwiched between the detection electrode and the ground potential surface, and a change in capacitance corresponding to this change in dielectric constant is detected by the detection electrode. That capacitance change is applied to the resonator of the tuned circuit. The resonator of the tuning circuit changes its tuning point in accordance with the change in capacitance, and the electrostatic sensor circuit outputs a voltage signal corresponding to the change in the tuning point as a sheet thickness detection signal.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. 1st
A first embodiment of a paper sheet thickness detecting device according to the present invention is shown in FIGS.

In these figures, a passage path 2 of a conveyance system through which paper sheets 1 such as banknotes, copy paper, plastic film, cloth, etc.
An electrode plate 9 functioning as a detection electrode and a roller 30 are arranged facing each other. This roller 30 is made of rubber or synthetic resin, and the zero rotation shaft 31 is rotatably fitted into a synthetic resin rotation shaft 31 and is fixed to the tip of a movable arm 32 made of a conductor. A rotation support shaft 33 is fitted near the proximal end of the movable arm 32, and the movable arm 32
is rotatable on this rotational support shaft 33. Movable arm 3
One end side of a spring 34 is locked to the base end side of the spring 34, and this spring 34 constantly pulls the movable arm 32 upward with elastic restoring force, and moves the movable arm 32 counterclockwise around the rotational shaft 33 as a fulcrum. The roller 30 is brought into pressure contact with the electrode plate 9 by rotation. 20 A roller 30, a movable arm 32, a rotating support shaft 33,
The spring 34 constitutes a pressing means that utilizes the lever principle of the movable arm 32. The movable arm 32 is connected to the ground and serves as a ground potential plane (when the rotating shaft 31 is made of a conductor, both the movable arm 32 and the rotating shaft 31 serve as a ground potential plane), and the electrode plate 9 is connected to the lead 22. It is connected to the electrostatic sensor circuit 23 via.

An example of the electrostatic sensor circuit 23 is shown in FIG.

This electrostatic sensor circuit includes an oscillation circuit 14, a ceramic resonator 15 functioning as a tuning circuit, a detection circuit 16,
The amplifier circuit 17 and the AFC (Automatic F
(requency control) circuit 18, this circuit is formed on a circuit board,
This circuit board is covered by a shield case. The shield case is connected to the ground plane of the circuit.

The oscillation circuit 14 has a built-in ceramic resonator 19, and has a 0°5
An ultra-high oscillation frequency signal of GHz to 10 GHz, IGHz in this embodiment, is output. An electrode plate 9 functioning as a detection electrode is connected via a lead 22 to the output terminal side of the ceramic resonator 15 functioning as a tuning circuit. In order to stabilize the resonant frequency of the resonator 15, the length of the conductor from the surface of the electrode plate 9 to the ceramic resonator 15 via the lead 22 is nλ/4 (n is an integer of 1 or more, λ is shorter than the wavelength of the resonant frequency. The ceramic resonator 15 changes the tuning point with the oscillation circuit 14 in response to the change in capacitance detected by the electrode plate 9, and generates a voltage signal corresponding to the change in the tuning point using the oscillation frequency of the oscillation circuit as a carrier wave. output as an amplitude modulated signal.

The detection circuit 16 detects the amplitude modulation signal output from the ceramic resonator 15, converts it into a signal in the thickness detection signal band of the paper sheet 1, and applies this to the amplifier circuit 17. The amplifier circuit 17 amplifies the detected output and supplies it to a desired signal processing circuit. The AFC circuit 18 corrects changes in the tuning point of the ceramic resonator 15 due to environmental changes, etc., and stabilizes the tuning point of the ceramic resonator 15.

The first embodiment is configured as described above, and below,
In the state shown in FIG. 1 in which the paper sheet 1 is not conveyed to the zero passage path 2 which explains the thickness detection operation of the paper sheet 1, the electrode plate 9 and the movable arm 32 as a ground potential surface are used as intermediary members. They are pressed into contact with each other without any gaps through the rollers 30, and the equivalent circuit of the electrode portion at this time is shown in FIG. 4(a). In this equivalent circuit, R1 is the resistance of the wire 22, C1
Similarly, is the capacitance of the lead 22, Re is the contact resistance of the contact portion between the roller 30 and the electrode plate 9, Cc is the capacitance of the contact portion, and R3 is the resistance of the electrode plate 9.

As shown in FIG. 2, when the paper sheet 1 is being conveyed and is about to enter between the roller 30 and the electrode plate 9, the roller 30 resists the biasing force of the spring 34 to force the paper sheet 1 The paper sheet 1 is rotated clockwise around the rotating support shaft 33 as a fulcrum by the thickness of the paper sheet 1, and the sheet sheet 1 is received, and the sheet sheet 1 is sandwiched between the electrode plate 9 and the electrode plate 9 by the biasing force of the spring 34. The equivalent circuit of the electrode part at this time is the 4th[1J(b)
The change in dielectric constant that depends only on the thickness and material of the paper sheet 1 is expressed as the capacitance change component C4 in FIG. 4(a).
It becomes a state where it is added in series to the circuit. In other words, roller 3
When the paper sheet 1 is sandwiched between 0 and the electrode plate 9,
The electrode plate 9 detects a change in capacitance corresponding to a change in dielectric constant determined by the thickness of the paper sheet 1 and its material. Therefore, if the paper sheets are made of the same material,
The dielectric constant changes corresponding to the change in thickness, and this change in thickness is detected by the electrode plate 9 as a change in capacitance. This change in capacitance is applied from the electrode plate 9 to the ceramic resonator 15 of the electrostatic sensor circuit, and the ceramic resonator 15 outputs an amplitude modulation signal corresponding to the thickness of the paper sheet l.

In this embodiment, since the change in capacitance is detected using the change in the tuning point of the ceramic resonator 15,
It is possible to detect a minute change in capacitance on the order of Xl0-'PF, and from this, it becomes possible to detect the thickness of a paper sheet 1 such as thin paper with ultra-high sensitivity.

In this first embodiment, the pressing means is constructed using the lever principle of the movable arm 32, but this pressing means can be constructed in various other ways.

For example, as shown in FIG. 5, a movable body 36 is fitted into the holding frame 35 so as to be vertically movable, a compressed spring 37 is interposed between the movable body 36 and the holding frame 35, and the spring 37 is attached. The movable body 36 may be brought into pressure contact with the electrode plate 9 by force. In this case, if the holding frame 35 is formed of a conductor, this holding frame 35 will constitute a ground potential surface. Of course, if the movable body 36 is formed of a conductor, this movable body 36 will also constitute a ground potential plane.

Further, as shown in FIG. 6, a leaf spring 38 may be provided so as to be in constant pressure contact with the electrode plate 9, and this may be used as a pressing means.
In this case, the leaf spring 38 constitutes a ground potential surface.

Further, as shown in FIG. 7, the paper sheet 10 passing route 2
The first roller 40 and the second roller 41 are brought into contact with each other and arranged to face each other in the vertical direction, the rotation bearing 42 of the lower second roller 41 is configured as a detection electrode, and the upper first roller 4
0 rotary bearing 44 is configured as a ground potential surface, and the first
The roller 40 may be brought into pressure contact with the second roller 41 by a pressure spring 43, and the pressure spring 43 may be configured as a pressing means.

Furthermore, in the first embodiment, the electrode plate 9 is used as a detection electrode, but the movable arm 32 is connected to the ceramic resonator 15 and used as a detection electrode, and the electrode plate 9 is connected to the ground, for example, and used as a ground potential surface. good.

8 and 9 show a second embodiment of the paper sheet thickness detecting device according to the present invention.

In this second embodiment, an electrostatic sensor circuit and a detection electrode are housed in the National Sports Festival 10, and the other configurations are the same as the first embodiment. As shown in FIG. 1O, the national body 10 has a housing recess 11 therein, and a circuit board 12 on which an electrostatic sensor circuit is formed in the housing recess
is accommodated. This circuit board 12 is covered by a shield case 13, and the circuit board Fi12 is accommodated in the accommodation recess 11 of the national body 10 while being covered by the shield case 13.

The proximal end of a needle-shaped detection electrode 20 is connected and fixed to the circuit board 12 by soldering or the like, and the distal end of the detection electrode 20 is housed and fixed in an electrode insertion hole 21 provided in the national body 10. ing. A roller 30 of a pressing means configured in the same manner as in the first embodiment is pressed against the detection electrode 20. Note that 10a in the figure is a reference plane of the national polity 10, and this reference plane and the tip surface of the detection electrode 20 are aligned. Further, this reference surface is subjected to various treatments such as chamfering in order to improve the passage of the paper sheet l.

Also in this second embodiment, when the paper sheet 1 does not pass between the national polity 10 and the roller 30, the roller 30 is in pressure contact with the detection electrode 20 without any gap, as shown in FIG. The equivalent circuit of the electrode part at that time is shown in Figure 11 (
It is expressed as shown in a). In other words, the equivalent circuit at this time is a resistance R4 of the detection electrode 20, a parallel circuit of a contact resistance RC and a capacitance CC at the contact portion between the detection electrode 20 and the roller 30, and a pressing means consisting of the roller 30 and the movable arm 32. It is expressed as a circuit in which a resistor RA of a portion and a parallel circuit of a capacitor OA of that portion are connected in series.

In this state, as shown in FIG. 9, when the paper sheet 1 is conveyed along the passage path 2 and enters between the roller 30 and the national body 10, its equivalent circuit is as shown in FIG. 11(b). As shown in Fig. 11(a), the change in capacitance C- corresponding to the change in dielectric constant depending on the thickness and material of the paper sheet 1 is shown in Fig. 11(a).
is added in series to the circuit. In this second embodiment as well, the lines of electric force from the detection electrode 20 to the movable arm 32 functioning as a ground potential surface pass through the inside of the paper sheet 1. Changes in capacitance corresponding to the thickness of the body 1 are detected with ultra-high sensitivity, and the detection signal is output from the electrostatic sensor circuit.

In this second embodiment as well, the pressing means can take various forms, and as in the case of the first embodiment, the pressing means shown in FIGS. 5 and 6 can be adopted. .

Further, in this second embodiment, the detection electrode 20 is configured by being divided into a first electrode part and a second electrode part, the first electrode part being fixed to the circuit board 12 side, and the second electrode part being fixed to the circuit board 12 side. The parts are inserted and fixed into the electrode insertion holes 21 of the national polity 10, and when the circuit board 12 is accommodated together with the shield case 13 in the accommodation recess 11 of the national polity 10, the first electrode part and the second electrode part are restored to the spring state. Either the pressure welding connection is made using force (in this case, one of the first electrode part and the second electrode part is made of a conductor spring), or the connection is made electrostatically by facing each other with a certain minute gap between them. It is also possible to adopt a method in which
The work of assembling the shield case 13 into the housing recess 11 can be facilitated.

Note that the present invention is not limited to the above-mentioned embodiments, and can take various embodiments. For example, in each of the above embodiments, the ground potential plane is connected to the ground, but it is not necessarily necessary to connect it directly to the ground, and even if a pseudo ground is configured at high frequency, it will operate in the same manner as described above. When a circuit is driven with an ultra-high frequency signal of about IGHz, the shield case connected to the ground of the circuit and the ground potential surface become imaginary short-circuited, and the ground potential surface is configured to have the same potential as the shield case. Because you can.

〔Effect of the invention〕

The present invention is configured such that the ground potential surface and the detection electrode are arranged opposite to each other on the passage of the paper sheet, and the paper sheet is sandwiched between the ground potential surface and the detection electrode without any gap by the pressing means. , the electric lines of force from the detection electrode to the ground potential surface penetrate the inside of the paper sheet. Changes in dielectric constant, which is determined only by the thickness of the paper sheet and its material, can be detected as a change in capacitance, so there is no error at all, and the desired thickness of the paper sheet can be detected with ultra-high sensitivity. It becomes possible to detect the source.

Furthermore, as described above, the present invention is configured to detect the thickness of a sheet of paper by generating an electric field between the detection electrode and the ground potential surface and allowing the object to be detected to pass through the electric field without any gaps. There are no problems such as difficulty in assembling the roller or generation of overshoe output due to reaction when the roller rides on the paper sheet, which is the case when a potentiometer is used in the conventional method for detection. It is also so weak that it can be removed by processing it with an electric circuit. In addition, since the pressing force of the pressing means for sandwiching the paper sheet between the ground potential surface and the detection electrode without any gaps is sufficiently smaller than the pressing force of the potentiometer roller, when detecting the thickness, it is necessary to There's no need to put a load on it.

Furthermore, since the device of the present invention can be formed thinner and smaller than conventional potentiometers, it is possible to mount detection electrodes in a high density in the width direction of the paper sheet, which increases the width of the paper sheet. It is possible to detect finely directional thickness variations.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram showing a first embodiment of the paper sheet thickness detection device according to the present invention, FIG. 2 is an explanatory diagram of the thickness detection operation in the same embodiment, and FIG. 3 constitutes the present invention. FIG. 4 is a circuit diagram showing an example of an electrostatic sensor circuit; FIG. 4 is a circuit diagram showing an equivalent circuit of the electrode portion in the same embodiment when detecting the thickness of a paper sheet and at other times; FIGS. FIG. 7 is an explanatory diagram showing various other embodiments of the pressing means applied to the device of the same embodiment, FIG. 8 is a configuration diagram showing the second embodiment of the present invention, and FIG. An explanatory diagram of the thickness detection operation of a paper sheet, FIG. 10 is a configuration diagram of the main body of the apparatus constituting the same embodiment, and FIG. ) is a side view showing the national polity in cross section, Part 1
Figure 0 (C) is a bottom view of the main body of the device, Figure 11 is a circuit diagram showing the equivalent circuit of the electrode portion in the same embodiment, comparing the time when detecting the thickness of a sheet of paper and the time other than that. This figure is a perspective view showing a conventional thickness detecting device using a potentiometer, and FIG. 13 is an explanatory diagram of a waveform for detecting the thickness of a sheet of paper by the conventional device. DESCRIPTION OF SYMBOLS 1... Paper sheet, 2... Passing path, 3... Potentiometer, 4... Rotating shaft, 5... Arm, 6...
・Roller, 7... Spring, 9... Electrode plate, 10...
National polity, 11...Accommodation recess, 12...Circuit board, 13
... Shield case, 14... Oscillation circuit, 15...
・Ceramic resonator, 16...detection circuit, 17...
Amplifier circuit, 18... AFC circuit, 19... Ceramic resonator, 20... Detection electrode, 21... Electrode insertion hole, 22... Lead, 23... Electrostatic sensor circuit, 30
...Roller, 31... Rotating shaft, 32... Movable arm,
33... Rotating shaft, 34... Spring, 35... Holding frame, 36... Movable body, 37...- Spring, 38... Leaf spring, 4o... First roller, 41... Second roller, 42.44... Rotating bearing, 43... Pressure spring. Applicant Uchide Seisakusho Co., Ltd. Agent Patent Attorney Igarashi Kiyodai Jump No. 10

Claims (1)

[Claims] It has an oscillation circuit, and a tuning circuit that includes a resonator separate from the oscillation circuit, changes a tuning point in response to a change in external capacitance, and outputs a detection signal corresponding to the change in the tuning point. An electrostatic sensor circuit is provided, and a ground potential plane and a detection electrode that detects and supplies a change in capacitance to a resonator of a tuning circuit are arranged opposite to each other at positions sandwiching the paper sheet in the path through which the paper sheet passes. , at least one side of the ground potential surface and the detection electrode is provided with a pressing means for pressing the one side against the other side directly or indirectly through an intermediary member to sandwich the paper sheet without a gap. A device for detecting the thickness of paper sheets.