JPH05254693A - Paper sheet multiple feed detector - Google Patents

Abstract

PURPOSE:To provide a multiple feed detector which restrains the unstable condition of a paper sheet during transport at the same time, and is less affected by the existence of printing, paper quality or thickness, and changes in surface conditions or external conditions. CONSTITUTION:This multiple feed detector, which detects the multiple feed and dry feed of a paper sheet on a delivery supporting surface 16 which supports paper sheets during delivery, is provided with a pressurized air feed source 14, a nozzle means 10 which has an inlet throttle 11, and outlet throttle 12, and a back pressure chamber 13 between them, sprays pressurized air fed to the inlet throttle from the pressurized air feed source, taking a clearance X from the outlet throttle on the support surface, a pressure detection means 17 which generates an electric signal generated with by detecting the pressure of the back pressure chamber which varies according to the number of the paper sheets on the support surface which is the front surface of the outlet throttle, and a discriminating means 18 which discriminates the dry feed and multiple feed of the paper sheets by comparing the output signal of the pressure detection means with the reference signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is designed for double feeding of paper sheets, that is, they are supposed to be sent one by one, when the printed paper sheets are arranged in page order by a collator prior to bookbinding. The present invention relates to a detection device for detecting the fact that two or more sheets are overlapped and sent in the middle of conveyance, and more particularly to an air pressure conversion type double feed detection device.

[0002]

2. Description of the Related Art Paper sheets collected by a collator have various types such as thickness, surface condition, paper quality, and the like. As a method of non-contact detection of transmission, three methods of a light transmission method, a light reflection method and an ultrasonic wave transmission method are known. Each of these three methods has practical advantages, but it also has the following problems.

That is, the light transmission method is a method of irradiating a paper sheet being conveyed with light from a light source such as a light emitting diode and detecting double feeding by a change in the amount of light transmitted through the paper sheet.
In this method, the amount of transmitted light greatly changes depending on whether or not there is printing at the detection site on the surface of the paper sheet, so there is a drawback that erroneous detection occurs if the detection position shifts midway.

In the light reflection method, the paper sheet is irradiated with a laser beam or the like to capture the reflected light and the double feeding is detected by the triangulation method. Therefore, the surface color and luster of the paper sheet, the paper quality, Alternatively, the amount of reflected light changes depending on the surface condition of the detection site, such as unevenness of the surface due to paper cracking, so there is a limitation on the application that can be applied only when the surface condition of the paper sheet is constant, and the light transmission. As in the case of the method, there is a drawback that erroneous detection occurs if the detection position shifts midway.

The ultrasonic wave transmission method is disclosed, for example, in JP-A-62-70.
As disclosed in Japanese Laid-Open Patent Publication No. 707, the double feeding is detected by applying ultrasonic waves to a paper sheet being conveyed and detecting the intensity of the ultrasonic wave passing through the paper sheet. It is affected by the exposure of the kind and fluctuations of the surrounding air,
In addition, there is a drawback that erroneous detection occurs due to the influence of surface irregularities of paper sheets and changes in ambient temperature.

[0006]

Papers for which double feeding is to be detected during conveyance are papers of various thicknesses, plastic sheets,
There are various types such as metal foils, and the transportation speed of paper sheets is often relatively high, for example, about 1.5 m / sec in the case of a binding machine for bookbinding. Under such measurement conditions during conveyance, the detection target part of a paper sheet cannot be regarded as a rigid body.For example, the movement of the detection target part of each individual paper sheet conveyed one after another is It is in a random and unstable state, and the detection position for each sheet is not always the same, and is constantly changing. This unstable state is especially noticeable on thin paper sheets, and in addition to this, the presence or absence of printing, paper quality, thickness, surface condition, position of the detection target site, and changes in external conditions such as temperature adversely affect the detection results. This causes the development of a reliable double feed detection device to be hindered.

An object of the present invention is to simultaneously suppress the unstable state of paper sheets during conveyance, and to determine whether or not printing is performed.
It is an object of the present invention to provide a double-feed detection device that is not easily affected by changes in paper quality, thickness, surface conditions, and external conditions.

[0008]

According to the first aspect of the present invention, a double feed for detecting double feed and idle feed of the paper sheet on a feed support surface for planarly supporting the paper sheet being fed. The detection device has a pressurized gas supply source for supplying a pressurized gas of a predetermined pressure, an inlet throttle, an outlet throttle, and a back pressure chamber formed between both throttles, and from the pressurized gas supply source. Nozzle means for spraying the pressurized gas supplied to the inlet throttle from the outlet throttle at a predetermined interval onto the supporting surface, and the number of sheets on the supporting surface in front of the outlet diaphragm. The pressure of the back pressure chamber that changes due to pressure detection means for generating a corresponding amount of electric signal, and comparing the output signal of the pressure detection means with a preset reference signal And a determining means for determining double feeding , Whereby it is intended to achieve the above-mentioned problem.

According to a second aspect of the present invention, in the double feed detecting device for the paper sheets according to the first aspect, the pre-pressurized gas supply source includes pressure adjusting means for keeping the supply pressure constant. To do.

According to a third aspect of the present invention, in the double feed detecting device for the sheets according to the first aspect, the pressure value of the pressurized gas supplied to the inlet throttle is detected to generate a corresponding electric signal. The system further includes a supply pressure detection means, and the determination means is configured to perform compensation calculation of supply pressure fluctuation with respect to an output signal of the pressure detection means according to a detection output from the supply pressure detection means. Is.

[0011]

The double feed detection device of the present invention converts the displacement due to the thickness of the paper sheet at the detection target portion into air pressure and detects it. In short, it uses the principle of the air micrometer to detect the weight. It is to detect sending. The nozzle means has a back pressure chamber between the inlet throttle and the outlet throttle, and pressurizes the gas supplied from the pressurized gas supply source to the inlet throttle through the back pressure chamber to discharge the paper from the outlet throttle. Spray almost vertically to the transport support surface. When the number of paper sheets on the supporting surface changes, the back pressure of the outlet throttle changes correspondingly because the gap in front of the outlet throttle changes, and this back pressure change is detected as an electric signal by the pressure detecting means. To be done. The detected electric signal is compared with a predetermined reference signal by the discriminating means to discriminate between the idle feeding and the double feeding.

For example, assuming that the supply pressure to the inlet throttle is Ps, the ambient atmospheric pressure is Pa, and the detected back pressure is Pn, the back pressure Pn is Pa as the gap X in front of the outlet throttle becomes smaller.
To Ps. If there is no paper sheet in front of the outlet diaphragm and the back pressure value when the pressurized gas from the outlet diaphragm directly hits the transport support surface is P ₀ , the paper sheet is in front of the outlet diaphragm. The relationship between the back pressure value P ₁ when only one sheet exists and the back pressure value P ₂ when two sheets exist is P ₀ <P ₁ <P ₂
Becomes Therefore, P ₁ with a dead band width appropriate for the determination means
If the back pressure Pn detected by the pressure detection means is lower than the dead zone width than P ₁ and is lower than the dead zone width, it can be determined that the feed is double feed and the double feed is high.

In the double feed detecting device according to the second aspect, the pressure of the pressurized gas supplied from the pressurized gas supply source to the inlet throttle is kept constant by the pressure adjusting means, and therefore the discriminating means detects it by the pressure detecting means. By simply comparing the back pressure value with the reference value, it is possible to distinguish between blank feed and double feed.

The double feed detection device according to the third aspect deals with the case where the pressure of the pressurized gas supplied from the pressurized gas supply source to the inlet throttle fluctuates. In this case, the device further includes a supply pressure detection means. I'm out. The supply pressure detected by the supply pressure detecting means is used for compensating the back pressure detection signal which is compared with the reference signal in the discriminating means, whereby the back pressure change due to the fluctuation of the supply pressure is compensated.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle of the pneumatic conversion of displacement in the present invention will be explained together with an embodiment. In FIG.
Has an inlet throttle 11 and an outlet throttle 12, and a back pressure chamber 13 is formed between the both throttles. The inlet throttle 11 is supplied with pressurized air having a supply pressure Ps from an air source 14 such as a compressor via a regulator 15 as pressure adjusting means, and the pressurized air is supplied from the outlet throttle 12 via a back pressure chamber 13. It is sprayed almost vertically on the transport support surface 16. The pressure in the back pressure chamber 13 is detected by the pressure detector 17, and the detected output is compared with a reference value by the discriminator 18 to determine normal / idle feed / double feed. Incidentally, FIG.
In the figure, reference numeral 19 is a sheet of paper being conveyed.

In such a nozzle device 10, the flow rate of air passing through the inlet throttle 11 and the outlet throttle 12 can be expressed as follows by a well-known theoretical equation of adiabatic change.

[0017]

[Equation 1]

[0018]

[Equation 2]

Here, Q ₁ is the flow rate of the inlet throttle 11, Q ₂
Is the flow rate of the outlet throttle 12, Ps is the supply pressure, Pa is the ambient atmospheric pressure, Pn is the back pressure, d ₁ is the diameter of the inlet throttle 11, d ₂
Is the diameter of the outlet throttle 12, α ₁ is the flow coefficient of the inlet throttle 11, α ₂ is the flow coefficient of the outlet throttle 12, γ is the specific weight of air, g is the acceleration of gravity, k is the specific heat ratio, R is the gas constant, T Is the absolute temperature.

In the equilibrium state, Q ₁ = Q ₂ , and if the temperature is regarded as constant, the relational expression between the gap (displacement) X and the back pressure Pn of the outlet throttle is as follows.

[0021]

[Equation 3]

On the other hand, the formula (3) is theoretically established when the surface area of the cylinder formed by the cross-sectional area S ₂ of the outlet throttle 12, the diameter d ₂ and the displacement X is S ₂₂ , as shown in FIG. This is when S ₂ > S ₂₂ (4). This is because when the displacement X becomes large, the narrowest part of the air passage is defined not by the cylindrical surface area S ₂₂ but by the cross-sectional area S ₂ of the outlet throttle, the flow rate becomes constant no matter how much the displacement X changes, and the back pressure Is also constant.

[0023] ^{_{Here, S 2 = πd 2 2/}} 4, S 22 = πd 2 ·
Because it is X, when this (4) is substituted into equation organize for X, the _{X <d 2/4 (5} ).

When the setting of the gap X is explained by applying a specific numerical value to the embodiment of the double feed detecting device in the conveying line of the collator, usually, the sheets to be collated by the collator are special. The thickness is about 0.03 mm to 0.20 mm except for the ones. Considering the gap X required for detecting the idle feed and the double feed of the paper sheets of all these thicknesses by the detection system once set, the maximum value of the gap X and the support surface 1
The gap X _max with 6 must be 0.4 mm or more when the two thickest 0.2 mm sheets are stacked. Here, X _max is set as follows with some margin. X _max = 0.5 mm (6)

Conventionally, in the displacement-air pressure conversion in a general air micrometer, the gap is set to 0.01 to 0.10.
Although it is used in a narrow range of mm, the maximum gap should be used as X _max = 0.5 mm, which is extremely wide. The thinnest 0.
Entrance diaphragm 11 and exit diaphragm 1 for sensitively detecting double feeding of paper sheets from 03 mm to the thickest 0.20 mm
In order to determine the aperture size of 2, it is first necessary to set which gap value the maximum sensitivity point should be.

FIG. 3 shows the tip of the outlet throttle 12 and the transport support surface 1.
Figure 6 shows the relationship of various gap values with paper sheets on No. 6 above. Here, a thickness of 0.
Considering that the double feed of 1 mm paper is detected with the maximum sensitivity, the maximum sensitivity point is a point 0.15 mm from the support surface 16, so the gap X _s to the maximum sensitivity point is X _s = 0. 35mm (7).

After setting the maximum sensitivity point gap X _s , the diameter of the outlet throttle 12 is determined. Here is the way (3) described above is satisfied theoretically is when satisfying the gap X is (5), in the vicinity of X = d _2/4 according to the experiments (3) is It does not hold, and it holds only when the following expression (8) is satisfied. X ≦ 0.2d ₂ (8)

[0028] Now, when determining the d ₂ from equation (8) it as X because the maximum gap value X _max = 0.5, d ₂ ≦
It is 2.5 mm. Therefore, the diameter d ₂ of the outlet throttle 12 is set to d ₂ = 2.5 mm (9).

Next, in order to obtain the diameter d ₁ of the entrance diaphragm 11, the area ratio s (= 4Xd ₂ / d ₁ ² ) formed by the entrance diaphragm 11 and the exit diaphragm 12 and the detection sensitivity Kn (back) are calculated from the equation (3). Pressure P
It is necessary to know the relationship with the differential value of n). Figure 4 shows (3)
From the equation, the vertical axis represents the detection sensitivity Kn, the horizontal axis represents the area ratio s, and the sensitivity curve is a sensitivity curve drawn with the supply pressure Ps as a parameter. When Pn / Ps is 0.527 or less in absolute pressure, the area ratio s showing the maximum sensitivity Kn _max is 2 kgf / c when the supply pressure Ps is 2 kgf / c.
When changing to m ^2, it changes from 0.577 to 1.24. From FIG. 4, the diameter d ₁ of the entrance throttle 11 at which the maximum detection sensitivity Kn _max is obtained can be obtained by the following equation (10) if the gap X, the diameter d ₂ of the exit throttle 12 and the area ratio s are given. .. d ₁ = (4Xd ₂ / s) ^1/2 (10)

In the collating machine, about 0.5 kgf is used for a part of paper feeding.
Air pressure of / cm ² is used. If this is used as an air pressure source for double feed detection, the pressure is adjusted by the regulator 15 and the supply pressure to the inlet throttle 11 is 0.4 kgf.
/ Cm ² is suitable. From FIG. 4, the supply pressure Ps
Is 0.4 kgf / cm ^2, the area ratio s showing the maximum detection sensitivity is 0.8. Also, X is 0.35m from the formula (7).
Since m and d ₂ are 2.5 mm from equation (9),
Substituting into equation (10) gives d ₁ = 2.2 mm. Therefore, the actual diameter d ₁ of the entrance throttle 11 is set to d ₁ = 2.0 mm (11).

Since the parameters governing the pneumatic conversion of the displacement could be determined by the above calculation, simulation and experiment were carried out using these parameters, and the results shown in FIG. 5 were obtained. Curves of theoretical values in FIG. 5 are d ₁ = 2.0 mm, d ₂ = 2.5 mm, α ₁ =
0.7, α ₂ = 0.82, X _max = 0.5 mm, Ps =
It is a simulation result of the static characteristic curve by the theoretical formula (3) when 0.4 kgf / cm ² . The curve of the experimental value is an actual measurement value of the back pressure Pn when the distance from the state where the tip of the outlet throttle 12 and the transport support surface 16 are in contact with each other is increased to a gap of 0.5 mm. From FIG. 4, it can be seen that the theoretical value and the measured value are in good agreement, and the gap X = 0.
It can also be seen that, with a back pressure change of between 5 mm and 0.3 mm, a blank feed, a single feed, and a double feed for an object having a paper thickness of 0.1 mm can be sufficiently identified.

FIG. 6 shows the configuration of the apparatus of the embodiment when incorporated in the transport line of the collator. In FIG. 6, reference numeral 30 denotes a paper feeding device in the line, and a double feeding detection device is combined with the output side table surface as the supporting surface. This double feed detection device is similar to the nozzle device 20 described above.
And an air pressure source 21, a regulator 22, a supply pressure detector 23, and a back pressure detector 24.
The detection output of 4 is amplified by amplifiers 25 and 26, respectively, and then A
The A / D converter 27 digitizes it, the personal computer 28 discriminates it, and outputs it to the plotter 29. The design of the nozzle device in this case is similar to that described with reference to FIG.

7 to 10 show the results of the double feeding detection experiment of four types of paper sheets by the apparatus shown in FIG. In FIG. 7, when the imitation paper 26 g / m ^{2 has a} thickness of 0.03 mm, FIG. 8 shows the carbon paper 30 g / m ^{2 having a} thickness of 0.05 mm, and FIG. 9 shows the embossed paper 128 g / m ^{2 having a} thickness of 0.095 mm. In this case, FIG. 10 shows a case where the embossed paper has a thickness of 256 g / m ^{2 and a} thickness of 0.19 mm. From these results, it can be confirmed that the idle feeding and the double feeding of various different sheets can be sufficiently detected under the same setting of the nozzle device and the same detection condition.

[0034]

As described above, according to the present invention, by comparing the back pressure detection values of the nozzle device with the preset reference value as the threshold value, various commonly used paper sheets are used. It is possible to discriminate between normal feeding, idling, and double feeding under the same detection conditions, and it is possible to suppress the paper sheets at the detection site by blowing pressurized gas at the time of detection. At the same time, suppression of fraud is achieved. Even if there is unevenness in the paper quality of the paper sheets, unevenness of the surface due to the presence or absence of printing, or unevenness of the surface originally possessed by the paper sheets, the outlet diaphragm has a certain opening area, Since the gap with the leaf surface is much larger than the surface irregularities, the surface irregularities have the advantage that they do not affect the back pressure change and do not appear as disturbance.
Therefore, it is possible to detect a stable back pressure change during the transportation of the paper sheets and to discriminate between the idle feeding and the double feeding.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a configuration of a double feed detection device according to a basic principle of the present invention.

FIG. 2 is an enlarged explanatory view of a main part for explaining an action of an air flow in an outlet throttle of a nozzle device.

FIG. 3 is an explanatory diagram showing a relationship between a tip of an outlet throttle and a gap X.

FIG. 4 is a sensitivity curve diagram showing a change in detection sensitivity depending on the opening area ratio of the inlet and outlet throttles.

FIG. 5 is a diagram showing a theoretical value and a measured value of back pressure detection.

FIG. 6 is a configuration diagram showing an embodiment combined in a paper feeding line of a collator.

FIG. 7 is a diagram showing an actual measurement result in the case of an imitation paper having a thickness of 0.03 mm.

FIG. 8 is a diagram showing an actual measurement result in the case of carbon paper having a thickness of 0.05 mm.

FIG. 9 is a diagram showing an actual measurement result in the case of 0.095 mm thick embossed paper.

FIG. 10 is a diagram showing an actual measurement result in the case of an embossed paper having a thickness of 0.19 mm.

[Explanation of symbols]

 10 Nozzle Device 11 Inlet Throttle 12 Outlet Throttle 13 Back Pressure Chamber 14 Air Source 15 Regulator 16 Transport Support Surface 17 Pressure Detector 18 Discriminating Device

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tomohiko Ishikawa Nagaoka, Ibaraki-cho, Higashi-Ibaraki-gun, Ibaraki 3781-1 Industrial Technology Center, Ibaraki (72) Inventor Katsunori Ichimo, Naka-gun, Naka-gun, Ibaraki Shinchi 141-3 Bunshodo Seiki Co., Ltd. (72) Inventor Hiroshi Toki, Naka-cho, Naka-gun, Ibaraki Pref.

Claims (3)

[Claims] 1. A double feed detection device for detecting double feed and idle feed of a paper sheet on a conveyance support surface for planarly supporting a paper sheet being conveyed, and supplies a pressurized gas having a predetermined pressure. And a back pressure chamber formed between the inlet throttle, the outlet throttle, and both throttles, and the pressurized gas supplied from the pressurized gas supply source to the inlet throttle is supplied from the outlet throttle. Nozzle means for spraying on the supporting surface at a predetermined interval and the pressure in the back pressure chamber, which changes according to the number of sheets on the supporting surface in front of the outlet diaphragm, are detected and dealt with. A pressure detecting means for generating an electric signal of an amount, and a judging means for comparing an output signal of the pressure detecting means with a preset reference signal to judge the idling and the double feeding of the sheets. A multi-feed detection device for paper sheets. 2. The double-feed detection device for paper sheets according to claim 1, wherein the pressurized gas supply source includes pressure adjusting means for maintaining a constant supply pressure. 3. A supply pressure detecting means for detecting a pressure value of the pressurized gas supplied to the inlet throttle to generate a corresponding electric signal, wherein the determining means is based on a detection output from the supply pressure detecting means. 3. The double feed detection device for paper sheets according to claim 1, wherein the double feed detection device is configured to perform a compensation calculation of a supply pressure fluctuation with respect to an output signal of the pressure detection means.