JPS605996B2 - Paper-like object identification device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a paper-like object discrimination device, and in particular, it irradiates light over the entire surface of a paper-like object while it is traveling, and detects the transmitted light or reflected light in multiple bands. The present invention relates to a device that compares this detected amount with a detected amount (reference amount) of a paper-like object serving as a reference to determine whether the paper-like object is correct or not.

Various devices have been proposed for determining whether a paper-like object is correct or not, but most of them apply optical methods.

As an example, we focus on the partial characteristics of a paper-like object, that is, a specific part of the pattern printed on the paper-like object, and detect the reflectance, transmittance, color, etc. at that part, and then set this detected value as the reference value. You can compete to see if it matches or not, or “0”, “1”
An example of this method is to check whether the pattern when replaced with a signal matches the reference pattern.・However, this method involves temporarily stopping a moving paper-like object and irradiating light onto a specific area during that period of stopping.
Not only does it take a long time to determine, but if the paper-like object that is automatically conveyed is misaligned or twisted, there may be a misalignment between the detection position (where the light is irradiated) and the predetermined pattern part. occurs, making it impossible to make accurate determinations. Furthermore, according to this method, even if the paper-like object itself is normal, if there is dirt, wrinkles, etc. in the above-mentioned specific areas, the entire paper-like object is judged based on information only from that part, so this paper-like object cannot be considered normal. There is a risk that it will be excluded as such. As described above, the above-mentioned method has the drawback that the discrimination accuracy is affected by the conveyance conditions, local dirt on the paper-like object, and the like. Further, as another example of a conventional discrimination device, one shown in FIG. 1 is known.

This device consists of a detection section and a signal processing section, and the detection section is composed of a flute body 1, a light source 2, a reflector 3, a lens 4, a transparent partition plate 5, and a photoelectric conversion element 6. A paper-like object 8 runs at a constant speed in the darkness of the lotus body 1. The light generated from the light source 2 travels upward in the figure by the reflecting mirror 3, and uniformly illuminates the paper-like object 8 in the width direction (direction perpendicular to the traveling direction) via the lens 4 and the slit 9. The light transmitted through the paper-like object 8 is then guided to the photoelectric conversion element 6 via the slit 10 and converted into an electrical signal. Therefore, in this configuration, when the paper-like object 8 passes through the upper part of the slit 9, a distorted wave having a time function corresponding to the pattern of the paper-like object is obtained from the photoelectric conversion element 6. In order to recognize the entire surface of such a paper-like object 8, an integrator is provided in the signal processing section.

That is, the electrical signal obtained by the photoelectric conversion element 6 is amplified by the amplifier 12 and then passed through the plurality of band filters 13.
, 13, 13..., sine wave components 14, 14, 1 of several specific frequencies are added in parallel to
After that, each leaker 13, 13, 13...
Integrators 15, 15 connected to...
...is integrated during the running period and the amount of electricity is 16,16...
・・・・・・・・・・・・・・・and paper-like object 8
When it has completely left the slit 9, switches 17, 17 are activated.
Activate the memory device 18.
A comparator 20 compares an electric quantity 19 corresponding to a normal paper-like object stored in advance with the output of the integrator, and outputs a determination signal 21. According to the device shown in FIG. 1, the distorted wave amplified by the amplifier 12 recognizes the shape of the paper-like object 8 over the entire surface, and is passed through the wave leakers 13, 13, 13. The sine wave component is divided into a plurality of sine wave components by the integrator 15, 15, and 15 to integrate them over a scanning period, and a paper-like object is discriminated based on the amount of integration. Therefore, according to this method, the time required for discrimination is short, and even if the paper-like object being conveyed is misaligned or twisted, it can be accurately discriminated, and it is also resistant to stains, wrinkles, etc. in specific areas. However, the secondary device shown in FIG. 1 has the following drawbacks.

In other words, the graphic signal amplified by the amplifier 12 is a distorted wave that depends on the pattern of the graphic, but it is difficult to increase the resolution because the moving paper-like object is recognized through a wide slit. It is. Therefore, the distorted wave does not strictly indicate the characteristics of the pattern of the paper-like object, but is a so-called rough pattern converted into an electrical quantity. The device shown in FIG. 1 applies the distorted waves to a plurality of wave leakers, and extracts only the alternating current component of the distorted waves. As a result, when a simulated paper-like object made by a copying machine etc. is passed through this device, the pattern of the normal one and the simulated one is almost the same, so the amount of electricity obtained from each Obishiro leaker is This is almost the same as in the case of a normal object, making it difficult to accurately discriminate the above-mentioned simulated paper-like object.
In other words, the apparatus shown in FIG.
Although this technique is advantageous in identifying locally similar objects and local defects, the accuracy in identifying a simulated paper-like object to which the same pattern is added throughout is extremely low. Furthermore, according to the device shown in FIG. The amount of electricity stored is the amount of electricity obtained from each integrator when a normal paper-like object is passed through it in advance, so the scanning speed when obtaining the amount of electricity of a normal paper-like object to be stored in the memory 8 is (
(conveying speed) and the actual conveying speed of the paper-like object to be inspected must match.

If the carrier speed is no longer constant, the graphical signal obtained from the amplifier changes, and the amount of electricity obtained from each leaker changes. Therefore, the output of the integrator also changes, eventually causing an error in the comparator 20. Therefore, in the apparatus shown in FIG. 1, the permissible value of the comparison limit in the comparator 201 must be increased by taking into account the change in the conveyance speed, but widening the permissible value also reduces the discrimination accuracy. means to lower. The present invention was made in order to solve various problems associated with the follow-up device, and it is possible to accurately discriminate even pseudo paper-like objects made by copying machines, etc., and the discrimination result does not affect the conveyance speed of the paper-like object. The purpose of the present invention is to provide a discriminating device that prevents this from occurring.

According to the present invention, a pseudo paper-like object made using a copying machine or the like can be created to have almost the same pattern as a normal paper-like object, but the color distribution state (distribution state) over the entire surface of the paper-like object is Focusing on the large difference, we have made it possible to distinguish between normal paper-like objects and pseudo-paper-like objects from this color distribution state (distribution state). It is also possible to detect defects.

The present invention will be described in detail below with reference to the drawings.

The apparatus of the present invention also includes a detection section and a signal processing section, similar to the conventional example shown in FIG. FIG. 2 is a diagram showing an embodiment of the configuration of the discriminating device of the present invention. In this figure, 25-1, 2
5-2, 25-3, 25-4 are conveyor belts, 26-1,
26-2, 26-3, 26-4 are rotating rollers for driving each belt, and the paper-like object 27 is attached to the belt 25-4.
1, 25-2 and belts 25-3, 25-4, and conveyed in the direction of arrow 28. An illumination unit 32 composed of an illumination light source 29, a condensing lens 30, and a transparent guide 31 functioning as a slit is used to illuminate the paper-like object 27 being conveyed.
uniformly illuminates a predetermined area in the width direction. Light receiving unit 3
3 is a diffusion plate/guide plate 34 and a plurality of light receivers 35-1, 3
5-2, 35-3, etc., and the light transmitted through the paper-like object 27 is transmitted to the plurality of light receivers 3.
5-1, 35-2, 35-3...
・The light is received uniformly. Here, each light receiver has a different wavelength sensitivity, and receives transmitted light in multiple bands.
FIG. 3 shows an example of the wavelength sensitivity of each light receiver when the number of light receivers is three, for example. In FIG. 3, curve A shows the spectral sensitivity of the first light receiver 35-1, and curves B and C show the spectral sensitivity of the second and third light receivers 35-2 and 35-3, respectively. A photoreceiver with these spectral sensitivities can be easily realized, for example, by combining a silicon photodiode with an appropriate colored glass filter. FIG. 4 is a diagram showing the relationship between the illumination and light receiving areas and the traveling position of the paper-like object.

In this figure, 27 indicates a paper-like object, and 36 indicates an illumination and light receiving area, that is, the area of the transparent guide 31 and the diffuser plate 34 in FIG. In this figure, the paper-like object 27 is conveyed in the direction of the arrow 28 across the illumination and light-receiving area 36, but the area 36 is sufficiently spaced so that the paper-like object 27 does not run outside the area 36. Widely set. By doing this, it is possible to eliminate the effects of displacement or skew in the conveyance position of the paper-like object 27. In this way, when the paper-like object 27 passes through the region 36 and the transmitted light is received by the plurality of light receivers, the light receiver output is sent to the signal processing section.

The signal processing section will be explained again using FIG. 2. Light receiver 35-1, 35-2, 35-3, ......
The electrical signals obtained are sent to front layer amplifiers 37-1 and 37-3, respectively.
7-2, 37-3....... are amplified to appropriate zero-bell voltage signals, and the signals 38-1, 38-2, 38-3
......... These signals are then integrator 39-1,
Added to 39-2, 39-3……………. 40 again
is a photo switch that detects the light edge of the paper-like object being conveyed and generates a tip signal 41. This signal 41 is sent to a timing circuit 42, which receives this signal 41 and generates a timing signal for controlling the integration timing of each integrator. The integration time is the time from when the paper-like object 27 reaches the illumination and light-receiving area 36 to when it completely passes through. In this way, the signal power W,, V2, V8, integrated for a predetermined time by each integrator...
・It is.

Signal V. , V2, V3 are then added to an adder 43, which adds the signals V, , V2, V3 and outputs a signal Y. The divider 44-1 divides the signal V by the signal Y to obtain the signal V, and the divider 44-2 divides the signal V by the signal Y.
2 to obtain signal V2. In this way, the signal V,,V
2, . . . . . . . are obtained, these signals V, , V 2 . , ……………, guided by 45-3,
Reference voltage setting circuits 46-1, 46-2, .・・・． ...
......It is compared with each reference voltage set in 46-3. Reference voltage setting circuit 46-1, 46-2...
Each of the reference voltages set in 46-3 is determined in advance by passing a normal paper-like object through the system of the present invention. The reason for calculating the ratio of each band's output after making it a multi-band as described above is to eliminate the effects of local dirt, damage, overall dirt, and changes in the conveyance speed of the paper-like object. .

In other words, in the flow process of securities, etc., in addition to partial damage and stains, overall stains occur, and when considering unused paper-like objects as a standard, those that have been used for a long period of time are exposed to light throughout. Transmittance decreases to about 70% to 65%. This fact means that a normal determination cannot be made simply by detecting the amount of transmitted light, but this problem can be solved by making a determination using the relative value of the multiband output as described above. Furthermore, since the signals V, , V2 are completely unrelated to the transport speed, the allowable comparison limits in the comparators 45-1 and 45-2 can be minimized. Each comparator compares the input signal and the reference signal, and if the difference between the two is within a predetermined range, it outputs a signal “1”, and if it is outside the range, it outputs a signal “0”.
” is output.

Each of these outputs is then led to an AND circuit 47,
If the AND condition of the circuit 47 is satisfied, its output Vo becomes “1”.
”, the paper-like object to be tested is determined to be normal, and if Vo is "0", the paper-like object to be tested is determined to be abnormal.Now, regarding a certain type of reference paper-like object, 3 The outputs of the light receiving system for the two bands are V, , V2, and V3, and the fluctuation rate of the transmittance of each band of an arbitrary paper-like object is K.
,,K2,K3, Y=K,V, 10k2V20k3V3 V,=k,V,/Y V2=k2V2/Y.

Except in special cases, even if the transmittance changes due to overall dirt, almost no spectral deviation is observed. That is, except for special cases, it can be said that k, main k2 character k3=k. Therefore, each value above becomes: Y;k(V, 10V20V3)=kY.

VI〒kVI/kY.

V2≠kV2/kY.

However, Yo of V and Vo2 of V are values related to a paper-like object serving as a reference.

Therefore, since V, , V2 are values from which fluctuation factors that occur during the distribution process are removed, the variation in detected values is small, and a narrow tolerance range can be set, allowing highly accurate identification. In the above equation, the three outputs V, , V2, V3
Since the outputs V, , V2 are obtained by dividing the individual outputs by the added value Y, overflow of the divider (when the numerator is larger than the denominator) is completely prevented. When there are no hard constraints such as divider overflow, V,′=
A similar effect can be obtained by determining the output ratio using V, /V3, V2'; V2/V3, etc., and performing discrimination based on V,', V2', V3. As described above, in the present invention, light transmitted through a paper-like object is received by a plurality of light receivers, and each light receiver photoelectrically converts signals in different wavelength regions, and then the electrical signals obtained by each light receiver are converted into electrical signals. is introduced into the integrator and integrated for the scanning time, the ratio of the sum Y of each integral value obtained in this way and each integral value is taken, and this ratio V,, V2 and each of the above sum Y are calculated as follows. It is designed to obtain a judgment result by comparing with the value.

Therefore, according to the present invention, the time required for discrimination is short, and in addition to being resistant to misalignment and local stains during transportation, it is possible to discriminate based on the hue distribution ratio over the entire surface of a paper-like object. Therefore, it is possible to easily distinguish pseudo paper-like objects made with almost the same pattern by a photographing device or the like. In addition, according to the present invention, the result of taking the ratio of the multiband output and each band output is compared with the reference value, so the allowable value of the comparison limit in the comparator can be minimized, and the discrimination Accuracy can be increased. In the above description, a case has been described in which light transmitted through a paper-like object is photoelectrically converted, but reflected light may be subjected to optical fin conversion.

Furthermore, in the embodiment shown in FIG. 2, the ratio between the signal Y and the signal V is taken to obtain the signal v, and the ratio between the signal Y and the signal V2 is taken to obtain the signal v2, and these signals v,,v2Y were led to each comparator, and the output signals from each comparator were ANDed, which was used as the discrimination result.As a result of the experiment, the signal Y was the signal v,
, v2, it has become clear that the difference between the reference value and the simulated state of the paper-like object is not so great, so even if the output signal of the comparator 45-3 is not added to the AND circuit 47, the accuracy can be improved. It is possible to perform high discrimination, and even if the judgment result is obtained only from the ratio of the signal V to the signal Y, that is, the signal v, it can accurately eliminate pseudo paper-like objects that have almost the same pattern as normal paper-like objects. can do.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing the configuration of a conventional discrimination device, FIG. 2 is a diagram showing an example of the configuration of the present invention, and FIG. 3 is a diagram showing the spectral characteristics of a plurality of light receivers used in the device of the present invention. 4 are diagrams for explaining the relationship between the transportation state of a paper-like object and the irradiation area in the apparatus of the present invention. 25-1 to 25-4... Conveyor belt, 26-1
~26-4...Rotating roller, 27...Paper-like object, 29...Light source, 30...Condensing lens, 31...Transparent Guide, 34... Diffusion plate/guide plate, 35-1, 35-2, 36-3... Light receiver, 37-1, 37-2, 37-3... Amplifier, 39- 1, 39-2, 39-3...integrator, 43...
...Adder, 44-1, 44-2...Divider,
45-1, 45-2, 45-3... Comparator, 46-
1,46-2,46-3...Reference voltage setting circuit. Next 'Figure 2 Figure 4 Figure 4 Figure

Claims (1)

[Claims] 1. A light source that illuminates a moving paper-like object through a slit that defines a certain area over its width, and a light source that receives transmitted light or reflected light from the paper-like object that is irradiated by this light source, and has different spectral sensitivities. a plurality of light receivers, a plurality of amplifiers for respectively amplifying electrical signals obtained by these light receivers, and a plurality of amplifiers for integrating the signals obtained by these amplifiers during the period during which the paper-like object passes through the certain area. A plurality of integrators, a means for determining the ratio of electrical quantities obtained by these integrators, and a comparator for comparing the electrical quantities obtained by this means with each reference electrical quantity in the case of a reference paper-like object. A paper-like object discrimination device comprising: