RU2447499C1 - Device for measuring optical characteristics of document - Google Patents

Device for measuring optical characteristics of document Download PDF

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Publication number
RU2447499C1
RU2447499C1 RU2010152149/08A RU2010152149A RU2447499C1 RU 2447499 C1 RU2447499 C1 RU 2447499C1 RU 2010152149/08 A RU2010152149/08 A RU 2010152149/08A RU 2010152149 A RU2010152149 A RU 2010152149A RU 2447499 C1 RU2447499 C1 RU 2447499C1
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Russia
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radiation
document
sources
receivers
device according
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RU2010152149/08A
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Russian (ru)
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Петр Валерьевич Минин (RU)
Петр Валерьевич Минин
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Общество С Ограниченной Ответственностью "Конструкторское Бюро "Дорс" (Ооо "Кб "Дорс")
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Abstract

FIELD: information technology.
SUBSTANCE: device contains sources of radiation located together with receivers in interleaving order, and optical conductor which passes through both emitted and reflected from a document radiation, where radiation receivers can have angle of vision being essentially smaller than angle of divergence of radiation emitted by light source, contain lens and/or diaphragm to constrict field of vision. Additional receivers can be provided to capture passing radiation. Sources of radiation are distributed in groups with radiation of various spectra and combined in clusters.
EFFECT: simplification and downsizing of structure while providing high efficiency of radiation sources utilisation.
10 cl, 5 dwg

Description

Technical field

The invention relates to devices for measuring the optical characteristics of a document, such as the distribution of the reflection coefficient over the surface of a document. The invention can be used in devices for checking the authenticity of sheet documents, for example banknotes.

The ratio of the amount of radiation reflected from the document to the amount of radiation incident on the document is the reflection coefficient of the document. The distribution of the values of one or more optical characteristics of a document over its surface is otherwise called the optical image of the document. The study of the optical image of a document is one of the main ways to control the authenticity of documents, including banknotes. In addition to the reflection coefficient, measured for different wavelengths, devices for measuring optical characteristics are used to measure the transmittance of the document, as well as the luminescence parameters that occur under the influence of exciting radiation of a certain wavelength.

Devices for measuring optical characteristics typically comprise radiation sources and receivers, with the document included in the optical path between the source and receiver. The optical characteristic is determined by measuring the response of the receiver to the radiation of the source.

A device for measuring the optical characteristics of a document may be one-dimensional or two-dimensional. Two-dimensional devices use radiation detector arrays. Two-dimensional devices are able to obtain an image of a document without the need to move the device relative to the document.

One-dimensional devices contain a linearly arranged set of radiation receivers. To obtain an image of a document, it is necessary to move the device relative to the document and record the optical characteristics of individual sections of documents during this movement.

For example, a document moves along a channel near which a device for measuring the optical characteristics of a document is installed. By the time the document in the channel completely passes by the device, the device registers the distribution of optical characteristics over the entire surface of the document. The described device is of this type and is intended for installation near the channel in which the document moves.

State of the art

A device for checking banknotes in accordance with patent US 6172745 (publ. 09.01.2001, G06K 9/74). The known device contains a set of radiation sources, two flat optical fibers, delivering the radiation sources to the surface of the banknote, as well as a set of photodetectors that register radiation diffusely reflected from the surface of the banknote. The radiation sources are placed in the form of two linearly arranged groups, between which, also in a linear order, photodetectors are placed. Each of the photodetectors is equipped with an individual optical system that collects radiation from a specific area on the surface of the banknote. The optical fibers are bent towards each other in such a way as to create high illumination of the banknote in the field of view of the photodetectors. This device allows you to register the image of the banknote in the reflected radiation, when it moves in the direction perpendicular to the axis of the location of the receivers. This device was selected as a prototype.

However, it has a number of disadvantages. Firstly, it is difficult and not compact enough, because to ensure a high and uniform illumination of a banknote, you have to use two fibers and two groups of sources. Secondly, the prototype does not effectively use radiation sources. This disadvantage manifests itself in the case when, to increase the resolution of registration of the image of the banknote in the direction of its movement, it is necessary to make the field of view of the receivers in this direction narrower. Such a requirement is relevant in the control of the authenticity of banknotes, since an increase in resolution allows a more detailed study of the signs of authenticity. The system of two bent optical fibers illuminates a wide band on the surface of the banknote, so a significant part of the radiation does not fall into the narrowed field of view of the receivers and is wasted. The lack of efficiency in the use of radiation causes an additional increase in the number and / or power of light sources, which leads to a complication and / or cost of construction.

Disclosure of invention

The objective of the invention is the construction of a simple and compact device for measuring the optical characteristics of a document, which would allow you to register an optical image of a document with high resolution in the direction of its movement.

The technical results of the claimed device is to simplify and reduce the dimensions of the structure, high efficiency of the use of radiation sources. An additional technical result of the invention is the possibility of increasing the resolution of the registration in the direction of movement of the document.

The claimed technical result is achieved due to the fact that the device for measuring the optical characteristics of the document contains radiation sources that are optically coupled to the document transport channel through the light path, radiation receivers placed together with the radiation sources along a straight line in alternating order and optically coupled to the document transport channel through the light path, the light guide, which is at least part of the light path, having a first and second end, and t kzhe reflecting side and which provides the passage of radiation from the first end to the second and from the second end to the first, the layout area sources and receivers optically coupled to the first fiber end and a second end of the optical fiber is optically coupled to the document transport path.

An additional technical result is achieved due to the fact that in the device for measuring the optical characteristics of the document, the radiation detectors have a field of view angle substantially less than the angle of divergence of the radiation emitted by the light sources.

An additional technical result is achieved due to the fact that the radiation receiver is equipped with a lens that narrows the field of view.

An additional technical result is achieved due to the fact that the radiation receiver is equipped with a diaphragm that narrows the field of view.

An additional technical result is achieved due to the fact that in the device the radiation sources are distributed in groups, and the sources in each of these groups emit radiation of a certain range of wavelengths, and are configured to turn on and off simultaneously, while the radiation sources are combined into clusters containing sources from different groups, and clusters are arranged in alternation with radiation receivers.

An additional technical result is achieved due to the fact that the device additionally has at least one radiation receiver arranged to detect radiation passing through the document.

The use of a light guide in the light path, which ensures the passage of radiation from the first end to the second and vice versa, allows you to place both radiation sources and its receivers on one side of the document transportation channel, which makes it possible to analyze radiation reflected from the document and at the same time significantly reduce the dimensions and simplify the design of the device.

High efficiency of the use of radiation is ensured by the presence of a fiber used both for the passage of radiation from sources and for the passage of radiation reflected from the document. In this case, the optical coupling of the second end of the fiber with the surface of the document can be performed with high energy efficiency. With a sufficiently small distance between the document and the second end of the fiber, the radiation from the sources emerging from this end forms a flare region on the document, the size of which only slightly exceeds the size of the second end of the fiber. For the same reason, a large fraction of the radiation diffusely reflected by the document reaches the second end of the fiber. When diffusely reflected radiation enters the fiber through its second end, it for the most part reaches the first end of the fiber.

If the fiber is made without a reflective coating, then the propagation of radiation in it occurs due to re-reflection from the side faces in the mode of total internal reflection. If the fiber is surrounded by air and is made of glass or transparent plastic with a refractive index of 1.44-1.65, which is common for these materials, then total internal reflection occurs for all rays entering the fiber. Under conditions of severe contamination or dusting of reflecting faces, the total internal reflection is disturbed in the places where dust or dirt particles are deposited, which can lead to radiation losses. To exclude the influence of dust and contaminants, the light guide can be made by applying a reflective coating to the side faces.

Certain radiation losses occur due to reflection of radiation from the input and output ends of the fiber. For most glasses and transparent plastics, these losses are negligible if the angle of incidence does not exceed about 60 degrees. Note that in the case of diffuse reflection close to that described by Lambert's law, the vast majority of the radiation power is reflected at an angle of less than 60 degrees.

In the prototype, an increase in resolution in the direction of movement of the document is achieved by narrowing the visible area for the receiver on the document due to shielding. Since the result of shielding is a useless loss of radiation, this method leads to a sharp decrease in the efficiency of use of radiation sources. Unlike the prototype, the claimed invention allows to increase the resolution while maintaining high efficiency of the use of radiation sources.

We will call the width the size of the fiber in the direction of the line of location of sources and receivers, and the thickness - its size in the direction perpendicular to this line. The length of the fiber we will call the length of the optical path between its first and second ends.

The thickness of the fiber determines the size of the area of illumination on the document, which is measured in the direction of movement of the document. The radiation from this area, reflected by the document, is delivered to the receivers. By the level of radiation reaching the receiver, one can judge the reflection coefficient of the document.

Thus, the reflection coefficient of a document is measured in the region specified by the thickness of the fiber. The size of this area, in fact, determines the resolution of the device, measured in the direction of movement of the document, upon receipt of the image of the document. The smaller this size, the higher the resolution.

Optimization of the geometric parameters of the fiber and its location in the device allows for high resolution in the direction of movement of the document while maintaining high radiation efficiency. The optimal relative position of the fiber and the receiver allows energetically efficient connection of the receiver with the first end of the fiber. For this, it is necessary that the first end of the fiber completely covers the field of view of the receiver. The specified condition ensures that the receiver receives the largest amount of reflected radiation. Namely, if the condition is met, the same energy gets into the photodetector, minus the small propagation loss in the fiber, as if the receiver was located directly near the illuminated area of the document.

To ensure high resolution in the direction of movement of the document, it is necessary to choose the thickness of the light guide slightly less than the size (in the same direction) of the smallest object on the document that needs to be optically resolved. The thickness of the fiber can be structurally set over a wide range, without significant deterioration in the efficiency of use of radiation. It can be noted that reducing the thickness of the fiber does not require changing the angle of the field of view of the receiver if the fiber and the receiver are optimally positioned relative to each other.

Additional optimization of the parameters of the receivers makes it possible to increase the resolution also in the direction of the line of sources and receivers. Each of the receivers receives radiation from its portion of the flare region on the document. The linear size of this section in the direction along the line of location of the sources and receivers is determined by the angle of the field of view of the receiver and the length of the fiber. It can be found in the reverse rays. To do this, it is necessary to construct the course of the extreme rays emerging from the receiver at an angle of the field of view, then entering the fiber through the first end, then propagating through the fiber, then leaving the fiber through the second end and, ultimately, reaching the surface of the document. The distance between the rays on the surface of the document and gives the size of the area from which the receiver receives radiation. The size of this section is determined by the requirements for the resolution of registration of the image of the document and, generally speaking, should be as small as possible. Accordingly, the angle of the field of view of the receiver should be as small as possible.

Optimization of parameters of radiation sources can be aimed at achieving the maximum possible uniformity of illumination, since uneven illumination leads to errors in the measurement of the optical characteristics of the document. To increase uniformity, it is important that the exposure areas from individual emitters overlap substantially on the surface of the document. To increase the overlap, it is necessary, as far as possible, to increase the size of the exposure zone of one emitter. The path of rays from the emitter to the surface of the document is similar to the above path of rays to the receiver, except for their opposite direction. To increase the size of the exposure zone from the source, sources with a large divergence of radiation should be used. Therefore, in an optimally designed device, the angle of the field of view of the receiver is significantly less than the divergence of the radiation source.

For optimization purposes, narrowing the receiver's field of view can be achieved in two ways. Firstly, the radiation receiver can be equipped with an additional lens. An example of such a receiver, manufactured by many manufacturers, is a phototransistor in a plastic case with an integrated lens. Secondly, to narrow the field of view, a diaphragm can be used to cut off the side rays. Both of these methods can be used separately or together. It should be borne in mind that narrowing with the help of the diaphragm reduces the efficiency of using radiation from sources, since the radiation cut off by the diaphragm is uselessly lost. The use of the lens practically does not reduce efficiency. On the contrary, increasing the diameter of the lens allows you to collect radiation from a larger area and increase energy efficiency.

On the other hand, the lens does not provide a sharp boundary of the field of view, and a relatively small amount of energy can still enter the receiver from areas of the document that are far beyond the calculated field. On the contrary, the diaphragm provides a fairly sharp border of the field of view. Therefore, the most optimal is to use a combination of both options. Using the lens, the main narrowing of the field of view is set, and the side rays located outside the calculated field are cut off with the diaphragm. In this case, the energy loss is small, and at the same time errors are eliminated due to the entry into the receiver of lateral rays related to neighboring areas of the document.

When controlling the properties of a document, such as its authenticity, it is important to obtain the optical characteristics of the document recorded for several radiation wavelength ranges. To measure these characteristics, it should be possible to alternately illuminate the document with radiation from several different wavelength ranges. With this kind of lighting, the optical characteristics of a document can be measured successively for several different ranges. To this end, the sources are divided into groups, the sources of each of which emit radiation of a certain range of wavelengths, and are configured to turn on and off simultaneously. To ensure uniform illumination, sources belonging to different groups are combined into clusters, and the clusters themselves are arranged in alternation with radiation receivers. The concept of a cluster involves several sources located close to each other. Each of the clusters can be considered as a single radiation source with a switched radiation wavelength range.

The radiation that hits the surface of the document is partially reflected from it, partially absorbed, and the rest comes from the back of the document. The ratio of the amount of radiation coming from the back of the document to the amount of radiation incident on the document is the transmittance of the document. If the device is supplemented with at least one receiver placed with the possibility of detecting radiation transmitted through the document, the device will be able to measure the transmittance of the document. In order to find the distribution of the transmittance over the surface of the document, you can use well-known photodetector arrays, consisting of many photodetectors located along a straight line,

Such a ruler must be placed on the reverse side of the channel in which the document moves, opposite the second end of the fiber. The resulting image of the document can include both the distribution of the reflection coefficient and the transmittance, each of which can be measured for different ranges of radiation wavelengths.

The invention is illustrated by the following drawings.

Figure 1 shows a diagram of the passage of rays from a source to a document, in a plane perpendicular to the line of location of sources and receivers.

Figure 2 shows a diagram of the passage of the rays reflected from the document in a plane perpendicular to the location of sources and receivers.

Figure 3 shows the location of radiation sources and receivers along the width of the fiber.

Figure 4 shows a diagram of the passage of rays from sources and the course of reflected rays.

Figure 5 shows the location of imaginary images arising from re-reflection from the side faces of the fiber.

A device for measuring the optical characteristics of a document contains emitters 1, the radiation of which enters through the first 2 end of the optical fiber 3. This is shown in Fig. 1, in a projection directed along the line of location of sources and receivers. The radiation moves in the light guide 3 from its first 2 end to the second 4 end, either in a straight line or in a zigzag path due to total internal reflection from the large 5 lateral reflecting faces.

The flat fiber 3 has the shape of a rectangular parallelepiped, elongated in the direction of the line of location of sources and receivers. Document 6 moves in the transport channel, perpendicular to the plane of the light guide 3, in the direction shown by the arrow. After leaving the fiber 3 through its second 4 end, the radiation falls on the document 6 and forms a flare region on the document 7. Due to the small gap between the second 4 end and the document 6, the radiation diverges insignificantly during the passage from the second 4 end to the document 6. Therefore, the size of the flare region 7 is only slightly larger than the size of the second 4 ends.

As shown in FIG. 2, after diffuse reflection from the document 6, the radiation from the flare 7 is directed towards the second 4 end of the optical fiber 3. Due to the small gap between the second 4 end and the document 6, most of the radiation from the document 6 reaches the second 4 end face. Further, the radiation enters the fiber 3 through the second 4 end and propagates in it to the output through the first 2 end. At the same time, it can propagate both in a straight line and with re-reflection from the large 5 reflecting faces of the optical fiber 3.

The radiation emerging from the first 2 ends is limited by the diaphragm 8 and enters the radiation receiver 9. Each of the receivers is equipped with an integrated single-lens optical system, which reduces its angle of field of view.

As shown in FIG. 3, the emitters 1 and the receivers 9 are arranged in a line, along the first 2 ends of the optical fiber 3, in alternating order. The number and arrangement of emitters is selected in such a way as to ensure uniform illumination of the document. The emitters are arranged with a constant step S, while the extreme emitters are offset relative to small 10 reflecting faces by a distance S / 2. Note that the small 10 reflective faces are perpendicular to the large 5 reflective faces shown in FIG. 1. With this arrangement of emitters 1, the reflection of their radiation from small 10 reflecting faces can be considered as creating imaginary sources 1 ', extending a number of sources on both sides outside the range of sources 1. The step of imaginary sources 1' will also be S. Therefore, the illumination created on the surface of document 6 will periodically change with step S, but will not have additional unevenness near the edges of the channel 11 to move the document 6 and the corresponding small 10 reflecting edges of the fiber 3.

If possible for structural and economic reasons, it is necessary to increase the number of emitters 1 and reduce the distance between them so that each point in the area 7 of the illumination on the document receives radiation from as many sources as possible. Thus, it is possible to achieve the best uniformity of illumination. If each point receives radiation from a maximum of two sources, then the irregularity of illumination can be minimized by choosing the distance between the first and second ends of the optical fiber 3, as described in RF patent No. 2402815 (published on October 27, 2010).

Without changing the generality of reasoning, we can assume that the emitters 1 are in fact clusters consisting of two or more emitters emitting in different wavelength ranges. The small distance between the emitters that make up the cluster allows us to consider the cluster as a single emitter. For example, for use in a banknote counter, it is optimal to combine two emitters into a cluster, one of which emits in the infrared range, and the other in the visible. In this case, either all infrared emitters or all emitters of the visible wavelength range can be switched on simultaneously. This allows you to create the illumination of the document by radiation from any of the two ranges, for measuring the optical characteristics of the document in each of these wavelength ranges.

The receivers 9 are located in the middle between the respective emitters 1. The diaphragms 8 are arranged so as not to limit the path of the rays from the emitters 1 to the first 2 end of the fiber 3.

Figure 4 shows how diffusely reflected radiation propagates from the surface of the document 6 to the receivers 9a - 9e. The ray path in FIG. 4 is shown in a plane containing a line of location of sources and receivers. In this plane, the rays reaching the receivers propagate linearly in the optical fiber 3. Each of the receivers 9a-9e corresponds to a field of view 12a-12d on the document. The angle of the field of view of the receivers 9, together with the size and location of the diaphragms 8, determines the size of the visibility areas 12. To obtain the most accurate distribution of the optical characteristics on the surface of the document, the width of the visibility areas 12 is selected equal to S. Due to this, the measurement of the optical characteristics of the document is non-overlapping paths without gaps. This arrangement ensures that the characteristics of each point on the surface of the document will be taken into account in the data of only one of the receivers 9, and the resolution of the device will be the maximum possible for a given number of receivers.

In actual device manufacturing, it may be difficult to maintain the exact value of the size S of the scope. In this case, you should choose it slightly higher than S, so that random variations in the parameters of the device instances do not lead to gaps between the tracks and, as a result, to loss of information.

The size of the field of view 12 in the direction of movement of the banknote slightly exceeds the thickness of the light guide 3, as shown in FIG. Thus, the optical resolution of the device in the direction of movement of the document is determined by the thickness of the fiber 3, and in the direction perpendicular to it, by the width of the document transport channel and the number of receivers 9 used.

A large angle of divergence of the radiation of sources 1 is necessary to increase the uniformity of illumination of the surface of the document, while reducing the angle of the field of view of the receiver is required to increase the resolution of the device. Thus, the angle of the field of view of the receivers 9 is significantly less than the angle of divergence of the radiation of the emitters 1.

A single lens integrated into the receiver 9 does not provide a sharp boundary of the field of view, which affects the resolution of the device. If the diaphragm 8 were absent, then the radiation 9 that would not come from the field of view 12 corresponding to the given receiver could get into the receiver 9. For example, radiation from scopes 12a and 12c, which correspond to neighboring receivers 9a and 9c, could get into the receiver 9b. The use of aperture 8 allows you to cut off the peripheral rays and make the border of the field of view sharper.

In addition to increasing the resolution, limiting the field of view of the receiver 9 and the introduction of the diaphragm 8 can reduce the amount of spurious illumination entering the receiver. Spurious illumination is understood as radiation emanating not from the scope of the receiver on the surface of the document and therefore distorting the measurement results of the optical characteristic. In the claimed device, the source of spurious illumination can be a reflection of the radiation of sources coming from the fiber 3 through its second 5 end, back in the direction of the first 2 ends of the fiber and the receivers located behind it 9. Reflection level at small angles of incidence of the beam inside the fiber 3 (up to about 20 degrees) does not exceed 5%, and increases sharply with an increase in this angle over 35 degrees. Thus, the main problem is the radiation reflected from the second 4 ends at a large angle, and then coming out at a large angle from the first 2 ends of the optical fiber 3. The small field of view angle and its sharp boundary do not allow such stray light to penetrate into the receiver 9.

The high efficiency of using radiation sources is illustrated in Fig.5. When reflected from the large 5 faces of the optical fiber 3, imaginary images of the optical fibers 3 'and the illumination regions 7' appear. Upon further reflection, additional imaginary images appear (not shown in the figure), extending to infinity. This effect is well known as multiple reflection from parallel mirrors.

Thus, in the field of view of the receiver 9 is not only the real area of exposure 7, but also its imaginary image 7 '. Since the losses due to rereflection are small, the luminosities of imaginary images 7 'do not differ much from the luminosities of the real illumination region 7. Thus, the receiver 9 sees a virtually infinite, equally luminous plane consisting of the real illumination region 7 adjacent to each other and a plurality of its imaginary images 7' . Therefore, it will record almost the same energy level as if in the absence of a fiber, the receiver (along with aperture 8) was at a very small distance from the illumination region 7. Thus, the use of fiber 3 of the described configuration allows the energy efficiency of the measuring system to be high and small depending on the distance between the document 6 and the receiver 9. At the same time, the dimensions of the optical fiber 3 can be changed over a wide range so as to set the required dimensions of the field of view on the document, not changing receiver characteristics.

The above reasoning is valid provided that the first 2 end of the optical fiber 3 completely covers the field of view of the receiver 9. Otherwise, it cannot be argued that the receiver 9 sees an infinite, equally luminous plane, and therefore its response will be lower.

Claims (10)

1. A device for measuring the optical characteristics of a document, containing radiation sources optically coupled to the document transport channel by means of the light path, radiation receivers placed together with the radiation sources along the line in alternating order and optically coupled to the document transport channel by the light path, a light guide, at least part of the light path and elongated along the specified line, having a first and second end face, as well as reflecting sides, and providing Chiva passage of radiation from the first end to the second and from the second end to the first, the layout area sources and receivers optically coupled to the first fiber end and a second end of the optical fiber is optically coupled to the document transport path.
2. The device according to claim 1, in which the radiation detectors have an angle of view substantially less than the angle of divergence of the radiation emitted by the light sources.
3. The device according to claim 2, in which the radiation receiver is equipped with a lens that narrows the field of view.
4. The device according to claim 2 or 3, in which the radiation receiver is equipped with a diaphragm that narrows the field of view.
5. The device according to any one of claims 1 to 3, in which the radiation sources are distributed in groups, and the sources in each of these groups emit radiation of a certain range of wavelengths, and are configured to turn on and off simultaneously, while the radiation sources are combined into clusters containing sources from different groups, and clusters are arranged in alternation with radiation receivers.
6. The device according to claim 4, in which the radiation sources are distributed in groups, and the sources in each of these groups emit radiation of a certain wavelength range, and are configured to turn on and off simultaneously, while the radiation sources are combined into clusters containing sources from different groups, and clusters are arranged in alternation with radiation receivers.
7. The device according to any one of claims 1 to 3, in which there is additionally at least one radiation receiver arranged to detect radiation passing through the document.
8. The device according to claim 4, in which there is additionally at least one radiation receiver arranged to detect radiation passing through the document.
9. The device according to claim 5, in which there is additionally at least one radiation receiver arranged to detect radiation passing through the document.
10. The device according to claim 6, in which there is additionally at least one radiation detector arranged to detect radiation passing through the document.
RU2010152149/08A 2010-12-21 2010-12-21 Device for measuring optical characteristics of document RU2447499C1 (en)

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6172745B1 (en) * 1996-01-16 2001-01-09 Mars Incorporated Sensing device
GB2429767A (en) * 2005-09-06 2007-03-07 Int Currency Tech Banknote output control device that prevents supply of stacked banknotes
EP1730500B1 (en) * 2004-03-23 2007-07-11 Koenig & Bauer AG Optical system for creating an illuminating strip
RU2007109222A (en) * 2007-03-14 2008-09-20 Интернэйшнал Карренси Текнолоджиз Корпорэйшн (TW) Paper money identifier
RU2344481C2 (en) * 2003-05-23 2009-01-20 Гизеке Унд Девриент Гмбх Device to check up banknotes

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6172745B1 (en) * 1996-01-16 2001-01-09 Mars Incorporated Sensing device
RU2344481C2 (en) * 2003-05-23 2009-01-20 Гизеке Унд Девриент Гмбх Device to check up banknotes
EP1730500B1 (en) * 2004-03-23 2007-07-11 Koenig & Bauer AG Optical system for creating an illuminating strip
GB2429767A (en) * 2005-09-06 2007-03-07 Int Currency Tech Banknote output control device that prevents supply of stacked banknotes
RU2007109222A (en) * 2007-03-14 2008-09-20 Интернэйшнал Карренси Текнолоджиз Корпорэйшн (TW) Paper money identifier

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