JP2013083528A - Contact type optical line sensor device and method for identifying valuable page space - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform a precise truth and false determination function of a valuable page space in a contact type optical line sensor device which detects fluorescent components of the valuable paper space, etc. by using an ultraviolet light source.SOLUTION: When a UV block filter film 30 which blocks ultraviolet rays is coated or evaporated on a rod lens array 23, a slit 34 which penetrates the ultraviolet rays is provided, and the ultraviolet rays to be penetrated from the slit 34 is monitored, and contrasted with fluorescent output to be detected through the UV block filter film 30. Since the fluorescent output in proportion to fluctuation of light intensity of the ultraviolet rays directly irradiated and reflected on a base material part of a valuable page space is obtained even when the valuable page space is used at a market for a long time, aged, and contaminated, the fluorescent output from the valuable page space is exactly evaluated.

Description

  The present invention relates to an optical line sensor device for detecting fluorescence of a fluorescent substance embedded in a medium by irradiating the medium with ultraviolet light, and particularly for the purpose of discriminating securities, banknotes, credit cards, etc. (referred to as valuable paper or medium). The present invention relates to an optical line sensor device for close contact discrimination and a method for differentiating valuable paper using the same.

Recently, there has been a strong demand for a higher-speed and higher-performance discrimination system for authenticity determination in devices that handle banknotes such as ATMs and banknote processors.
As a method for discriminating these bills and securities, pattern identification using an optical line sensor device has been used for some time.
The optical line sensor device includes a reduction optical line sensor device combining a reduction lens, a mirror, and a CCD, and a contact type optical line sensor device using an equal magnification optical system such as a selfoc lens, and the reduction optical system is a system. The unit price is low, the resolution can be easily adjusted, and the focal depth is deep. However, there are disadvantages that the volume of the sensor is large and that there are many troubles due to dust and foreign matter. Therefore, a contact type optical line sensor device that is easy to maintain has been widely used recently.

On the other hand, on the valuable paper surface, ink, fibers, threads, etc. that emit fluorescence when irradiated with ultraviolet light have been embedded in predetermined portions of the valuable paper surface as marks for determining authenticity.
Therefore, in devices that handle valuable paper such as ATMs and banknote processors, it is becoming desirable to install a contact type optical line sensor device using ultraviolet light as a light source for a discrimination sensor used in the device. There is an expectation that the authenticity judgment ability will be further improved by irradiating the object with ultraviolet light and making fluorescent substances contained in the ink, paper, and constituent materials of the printed matter fluoresce and detecting the weak output and wavelength. Because.

This ultraviolet light contact optical line sensor device emits ultraviolet light from the mounted ultraviolet light source unit and irradiates the target medium, so that fluorescent components such as ink contained in the target medium are excited by ultraviolet light. Then, visible and infrared fluorescence is emitted, and light detection signals are collected at the light receiving unit to form image data, and authenticity determination is performed based on the collected image data.
Cold light source tubes, halogen lamps, ultraviolet LED light sources, etc. can be used as the light source of the ultraviolet light contact type optical line sensor device. Recently, however, a gallium nitride ultraviolet light LED with less visible light component and improved luminance has been developed. Is preferred.

As a line sensor constituting the light receiving part of the ultraviolet light contact optical line sensor device, a single crystal silicon photodiode array, a line CCD element, a sensor IC with a built-in sensor part, an amorphous silicon element, or the like is used.
Patent Document 2 below discloses a fluorescent sensor including an optical filter that transmits only an ultraviolet component (for example, about 300 to 400 nm) of light emitted from an ultraviolet light source.

  Patent Document 3 below discloses a fluorescence sensor in which an ultraviolet light cut filter that removes an ultraviolet component of light reflected from the surface of valuable paper is disposed in a light receiving element.

Japanese Patent Laid-Open No. 2002-230618 JP 2004-265208 A JP 2004-265104 A

In a line sensor using an ultraviolet LED light source, the fluorescence output emitted by ultraviolet light irradiation from ink such as numbers and patterns printed on valuable paper is extremely weak, and in the combination of the light source and the light receiving unit In some cases, sufficient detection sensitivity as a sensor cannot be secured.
In particular, when detecting fluorescence output by ultraviolet light irradiation, it is necessary to improve the ability to judge the authenticity of valuable materials and to detect valuable materials that have been used in the market for a long time or have become contaminated with sebum or detergent. Therefore, a method for discriminating the fluorescence output with respect to the ultraviolet light irradiation intensity is effective.

However, since the fluorescence output fluctuates in proportion to the amount of ultraviolet light directly irradiated onto the medium, there arises a problem that the fluorescence output cannot be measured accurately unless the intensity of ultraviolet light simultaneously irradiated can be monitored.
In addition, the irradiation intensity of the medium may decrease due to the operation of the ultraviolet light source for a long time, and it is necessary to correct this intensity with the amount of current supplied to the LED or to detect the performance life of the light source. come.

  Accordingly, the present invention provides a contact-type optical line sensor device that detects a fluorescent component such as valuable paper using an ultraviolet light source, and is provided with a slit that transmits ultraviolet light when the UV blocking filter film is formed. A contact type optical line sensor device capable of improving a precise authenticity judgment function on valuable paper by monitoring ultraviolet light to be compared with fluorescence output detected through a UV blocking filter film, and the same An object is to provide a method for identifying valuable paper.

  The present inventor has examined the fluorescence output of valuable paper by a light receiving sensor, and when forming a UV blocking filter film that blocks ultraviolet light, a slit that transmits ultraviolet light is provided there, and the ultraviolet light that is transmitted through the slit is transmitted. It has been found that a precise authenticity judgment function on valuable paper can be improved by monitoring light and comparing it with a fluorescence output detected through a UV blocking filter film.

  The contact type optical line sensor device of the present invention is a contact type optical line sensor device for detecting fluorescence of a fluorescent material embedded in a medium by irradiating the medium with ultraviolet light. A light receiving element that receives the reflected light reflected from the medium at a predetermined angle or the transmitted light that has passed through the medium, and an optical path from the ultraviolet LED light source to the light receiving element. A filter lens for blocking ultraviolet light emitted from the ultraviolet LED light source is installed in any one of optical paths from the ultraviolet LED light source to the light receiving element. Are provided with one or more slits that transmit ultraviolet light.

If it is this structure, the ratio of the fluorescence amount which passed the filter film on the basis of the ultraviolet light amount permeate | transmitted from a slit will be calculated | required by combining the filter film | membrane and slit which are ultraviolet light blocking materials. In other words, the amount of light transmitted through the slit can be used as a reference, and a fluorescence output proportional to the variation in the amount of ultraviolet light irradiated to the medium and reflected or transmitted can be obtained. Can be made.
In addition, the reflection intensity or transmission intensity of the medium may decrease due to aging or contamination of the medium, or the irradiation intensity to the medium may decrease due to aging of the light emitting element of the ultraviolet LED light source. Since a sufficient monitor light amount of the transmitted ultraviolet light can be directly obtained, this reduced intensity can be determined. Therefore, the medium can be a target for collection using this determination value. In addition, it is possible to correct an energization current to the light emitting element. Alternatively, the performance life of the light emitting element can be estimated.

  Further, in the present invention, there is a case where the output of ultraviolet light that has been reflected or transmitted by the base material itself of the valuable paper surface passing through the slit portion and the fluorescence output of ink or the like synergistically, and there are at least two slits for separating the output. It is preferable to be provided. This is because it is preferable to use light amounts collected from a plurality of locations in order to read out the output of the ultraviolet light component from the light amount transmitted through the slit and use it as a reference.

The filter film may be provided, for example, on the end surface of the rod lens. By providing on the end surface of the rod lens, it can be integrated with the rod lens, and the handling becomes convenient.
Further, the valuable paper surface discrimination method of the present invention is a method of detecting the light amount ratio of the fluorescence amount of the medium transmitted through the filter film to the ultraviolet light amount transmitted through the slit, using the contact optical line sensor device of the present invention. is there.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing a contact-type optical line sensor device that detects an image of securities, banknotes, and the like (hereinafter referred to as “medium S”). The contact-type optical line sensor device includes detection units 12 and 13 that are disposed opposite to a banknote transport path 11 for transporting the medium S linearly in the x direction. The banknote conveyance path 11 conveys the medium S straightly in a posture along the conveyance direction x. Each detection unit 12 and 13 is the same shape, and is arrange | positioned symmetrically. Hereinafter, the structure of the upper detection unit 12 will be mainly described.

  The detection unit 12 has a dimension in the length direction (y direction perpendicular to the paper surface in FIG. 1) compared to a dimension in the thickness direction (z direction in FIG. 1) and a dimension in the width direction (x direction in FIG. 1). It is quite long and has an elongated shape. The detection unit 12 includes an elongated box-shaped casing 16 provided with an opening in the lower direction, an elongated plate-shaped translucent cover 17 attached to the casing 16 so as to close the opening, and a casing. The unit body is housed in the body 16.

  The material of the housing 16 is preferably a substance such as a metal or a resin that is durable against ultraviolet light irradiation and does not emit fluorescence even when irradiated with ultraviolet light. For example, if it is a metal, it is iron, stainless steel, aluminum, copper, brass or the like. If it is a metal itself, it does not emit fluorescence, but it may fluoresce depending on the rust preventive material coated on the surface, and it is desirable to actually use ultraviolet light to confirm the presence or absence of fluorescence. As the resin, general-purpose resins such as polycarbonate, polyacetal, nylon, ABS, saturated and unsaturated polyester can be used. Similarly, the resin may emit fluorescence from added fillers, stabilizers, pigments, UV absorbers, etc., and it is preferable to adopt after confirming the presence or absence of fluorescence.

The translucent cover 17 is formed of a transparent material such as glass that transmits ultraviolet light and visible light, and a resin portion 36 is attached to one or both ends in the width (x) direction. The resin portion 36 has an inclined surface provided so as not to be an obstacle to the medium S being caught when passing through the detection unit.
The inside of the unit main body is partitioned by an elongated wall 18a extending in the length (y) direction. The partition wall 18a and both outer walls of the housing 16 define two elongated rooms U and V arranged in the width (x) direction. A room U located downstream in the x direction houses a light emitting element 29 of an ultraviolet LED light source and a rod lens array 23 that receives reflected light from the medium S. Further, a room T in which the sensor light receiving unit 24 is installed is partitioned in the back of the room U in which the rod lens array 23 is installed, that is, on the opposite side to the translucent cover 17. The sensor light-receiving part 24 has an elongated shape like the translucent cover 17, and is attached so that its length (y) direction coincides with the length (y) direction of the unit body. The sensor light receiving unit 24 has its image detection direction (−z direction) directed toward the translucent cover 17.

The sensor light receiving unit 24 takes in the light emitted from the rod lens array 23 through an opening 25 provided at the boundary between the room U and the room T. The room U and the room T are partitioned so that stray light other than the light that has passed through the rod lens array 23 does not enter the sensor light receiving unit 24.
The sensor light receiving unit 24 is formed by arranging sensor IC chips in which a light receiving element and a driver unit are integrated, and mounting them in a line on a substrate. The driver unit is a circuit part that generates and supplies a bias current for driving the light receiving element. In addition, a signal processing unit is connected to the sensor light receiving unit 24 to read and process a light detection signal of the light receiving element. The type of the light receiving element is not limited. For example, an amorphous silicon pin photodiode, silicon pn or pin photodiode is used, and is selected from the viewpoints of wavelength sensitivity characteristics, high speed operation, high resolution, and dynamic range.

  The rod lens array 23 has an elongated shape in the length (y) direction, and is disposed facing the sensor light receiving unit 24. The rod lens array 23 is a lens element for forming a fluorescent image of the medium S on the photosensitive surface of the sensor light receiving unit 24 as an equal-magnification erect image. The rod lens array 23 is attached to the housing 16 with the positions in the width (x) direction and the length (y) direction entirely superimposed on the sensor light receiving unit 24.

  The rod lens array 23 has a detection area of an image to be observed (the other focal point of the rod lens array 23 when the sensor light receiving unit 24 is one focal point of the rod lens array 23; referred to as an observation line). A predetermined distance outside the outer surface is set (this detection area is indicated by R1 in FIG. 1). A straight line extending from the detection area R1 and passing through the central axis (optical axis) of the rod lens array 23 is parallel to the z axis and reaches the photosensitive surface of the sensor light receiving unit 24. The detection area R1 also extends in the length (y) direction in the same manner as the unit body.

Further, as shown in FIG. 1, a UV blocking filter for preventing the ultraviolet light passing through the rod lens array 23 from entering the sensor light receiving unit 24 on the end surface of the rod lens array 23 facing the detection area R <b> 1. A membrane 30 is disposed.
The UV blocking filter film 30 is used for the purpose of accurately detecting the fluorescent component (visible light) emitted from the ink of the medium S irradiated with the ultraviolet light by cutting the ultraviolet light. However, when the medium S is irradiated with ultraviolet light, the fluorescent substance contained in the paper base material itself of the medium S may emit blue (400 to 450 nm) visible light fluorescence. Because of this blue fluorescence, red and green fluorescence emitted from patterns such as numbers printed on the medium S is buried, so that the wavelength characteristics of the UV blocking filter film 30 are improved for the purpose of improving the fluorescence detection capability. Need to adjust. Therefore, the wavelength blocking characteristic of the UV blocking filter film 30 cuts ultraviolet light and sharply blocks light having a wavelength of 410 nm or less, preferably 420 nm or less, more preferably 450 nm or less in the visible light region (400 nm to 700 nm). If so, the fluorescence of the paper substrate of the medium S can be reduced, which is preferable.

Further, it is preferable that the slope to be cut is steeper. For example, it is desirable for stabilizing the detection sensitivity that the difference (wavelength width) between the wavelength at which the light transmittance is reduced to 50% and the wavelength at which the light transmittance is reduced to 10% is in the range of 100 nm or less, particularly preferably 50 nm or less.
The installation position of the UV blocking filter film 30 is not limited to the end face of the rod lens array 23 that faces the detection area R1. For example, you may attach to the end surface facing the sensor light-receiving part 24. FIG. Further, it may be attached to either side of the boundary wall so as to close the opening 25 provided in the boundary wall between the room U and the room T apart from the rod lens array 23.

More generally, it may be disposed at any position between the detection area R1 and the photosensitive surface of the sensor light receiving unit 24. For example, you may attach in the form which covers the photosensitive surface of the sensor light-receiving part 24. FIG. In short, it is only necessary to prevent the ultraviolet light reflected in the detection area R 1 and passing through the rod lens array 23 from entering the sensor light receiving unit 24.
The UV blocking filter film 30 may be of any material and structure as long as it has the above-described wavelength blocking characteristics. For example, an ultraviolet light absorbing film in which an organic ultraviolet light absorber is mixed or coated in a transparent film, and a multilayer thin film of a dielectric thin film or metal oxide having different transmittance and refractive index such as titanium oxide and silicon oxide is deposited on the glass surface. The interference wave filter (bandpass filter) obtained by the above can be adopted.

The UV blocking filter film 30 may be configured independently, but may be directly vapor deposited on an optical member that transmits ultraviolet light, such as a lens or a protective glass plate. Similarly, an ultraviolet light blocking paint that is an organic material may be applied to an optical member that transmits ultraviolet light, such as a lens or a glass plate.
The room U is provided with an elongated ultraviolet LED light source 22 capable of irradiating ultraviolet light obliquely toward the detection area R1. The ultraviolet LED light source 22 is attached to the housing 16 in a state parallel to the sensor light receiving unit 24 along the length (y) direction of the unit body.

  The ultraviolet LED light source 22 is made of a light emitting element 29 made of a semiconductor element that irradiates ultraviolet light, and a transparent material such as an elongated glass for emitting the light of the ultraviolet LED light source 22 toward the detection area R1. And a light guide 27. The light emitting element 29 and the light guide 27 may be attached separately from each other, but it is preferable that the light emitting element 29 is disposed so as to contact the side surface of the light guide 27 and the both are integrated.

The light emitting element 29 is an LED element capable of emitting ultraviolet light having a wavelength of 300 nm or more. The ultraviolet light emitted from the light emitting element 29 can be obtained with a larger fluorescence output as the wavelength is shorter and the emission intensity is stronger. For example, in a gallium nitride system, an ultraviolet LED having a peak at a wavelength of 350 nm to 380 nm is practical and preferable.
Since the ultraviolet LED light source 22 also emits light including weak visible light, in order to remove this visible light, the light emission downstream of the ultraviolet LED light source 22, for example, between the ultraviolet LED light source 22 and the light guide 27, etc. A visible light cut filter (not shown) may be provided. If this visible light cut filter is provided, it is possible to further improve the monitoring accuracy and stabilize the performance. The material and structure of the visible light cut filter is, for example, a multilayer interference wave filter obtained by multilayer deposition of metal oxide or dielectric thin films on the glass surface.

Nothing is attached to the room V on the upstream side in the x direction in the unit main body because the lower detection unit 13 is not designed to detect transmitted light that passes through the medium S. . If necessary, the same thing as the transmissive LED light source 21 in the lower detection unit 13 may be attached.
Next, the transmissive LED light source 21 provided in the lower detection unit 13 in FIG. 1 will be briefly described. In the room V of the lower detection unit 13, visible light and / or infrared light is transmitted to the medium S. A transmissive LED light source 21 for irradiating the light is installed. The transmissive LED light source 21 includes a plurality of light emitting elements (not shown). Each light-emitting element can emit light having a wavelength of 800 nm or more, and three light-emitting elements that can emit light in a desired wavelength region of visible light corresponding to three primary colors such as red, green, blue (RGB) or cyan, magenta, and yellow. And an infrared light emitting element.

Each light emitting element can irradiate light of a different wavelength region. For this reason, each light emitting element has an electrode terminal (not shown), and has a circuit configuration capable of emitting light by switching each light emitting element simultaneously or temporally by selecting an electrode terminal to which a voltage is applied.
The lower detection unit 13 in FIG. 1 is opposed to the upper detection unit 12 in a posture in which the detection unit 13 is inverted 180 degrees around an axis along the length (y) direction with the banknote transport path 11 in between. That is, the detection unit 13 is provided with an opening in the upward direction of the elongated box-shaped housing 16, and the translucent cover 17 is attached to the housing 16 so as to close the opening. The detection unit 13 and the detection unit 12 face each other with the main surfaces of the translucent covers 17 and 17 parallel to the banknote transport path 11 with a gap of 1.5 to 3 mm.

  The element arrangement in the housing 16 of the detection unit 13 includes the transmissive LED light source 21, the ultraviolet LED light source 22 having the same configuration as the upper detection unit 12, a rod lens array 23, and a sensor light receiving unit 24. . The transmissive LED light source 21 is disposed relative to the sensor light receiving unit 24 of the upper detection unit 12, and the light emitted from the transmissive LED light source 21 and transmitted through the medium S passes through the rod lens array 23 and is sensored. The light enters the light receiving unit 24.

With this configuration, the sensor light receiving unit 24 of the upper detection unit 12 in FIG. 1 can detect a transmission image in the detection area R1.
Further, the sensor light receiving unit 24 of the lower detection unit 13 in FIG. 1 can detect the reflected image of the detection area R2 irradiated from the ultraviolet LED light source 22.
The ultraviolet LED light source 22 of the upper detection unit 12 and the transmissive LED light source 21 of the lower detection unit 13 are temporal in order to prevent the transmitted image and the reflected image from entering the sensor light receiving unit 24 at the same time. Light emission is controlled by switching.

  With the above configuration, the sensor light receiving unit 24 can detect the erect image of the reflected image irradiated from the ultraviolet LED light source 22 and reflected by the detection area R <b> 1 in FIG. 1 via the rod lens array 23. Further, the transmission image of the medium S irradiated through the transparent cover 17 on the surface of the housing is also formed as an equal-magnification erect image on the surface of the sensor light receiving unit 24 via the rod lens array 23 and can be detected.

In the embodiment of the present invention, the UV blocking filter film 30 is provided with a slit 34 that transmits ultraviolet light. An example of the shape of the slit 34 provided in the UV blocking filter film 30 will be described with reference to FIGS.
FIG. 2 is a perspective view of the rod lens array 23. A UV blocking filter film 30 is provided on the end surface of the rod lens array 23 opposite to the detection area R1. The UV blocking filter film 30 is divided in the length (y) direction, and ultraviolet light is divided. One or a plurality of slits 34 for transmission are formed. In FIG. 2, the number of slits 34 is “4”, but the number is not limited to this number.

The width along the length (y) direction of the slit 34 is indicated by “w”. When there are a plurality of slits 34, the sum of the widths w of all the slits is expressed as “W” in capital letters.
FIG. 3 is a partially enlarged view showing the end surface of the rod lens array 23 in an enlarged manner. The rod lens array 23 has a structure in which a plurality of rod-shaped lenses parallel to the thickness (z) direction (end surfaces of which are indicated by “23a”) are bundled and aligned in the length (y) direction. .

On this end face, a portion corresponding to the slit 34 is masked with any member, and the UV blocking filter film 30 is deposited or applied, and if the mask is peeled off later, the UV blocking filter film 30 having the slit 34 that transmits ultraviolet light is formed. Can be formed.
The width W of all the slits 34 may be 2 mm or more, preferably 5 mm or more in order to ensure the amount of transmitted ultraviolet light. The number of the slits 34 is not limited as described above, but it is preferable to provide two or more if possible in order to accurately monitor the amount of ultraviolet light reflected from the medium S.

If the sensor light receiving unit 24 detects light including ultraviolet light transmitted through the slit 34 using the rod lens array 23 provided with the slit 34 that transmits ultraviolet light together with the UV blocking filter film 30 as described above, In the signal processing unit 33, the amount of light can be recorded for each pixel of the light receiving element.
The signal processing unit 33 processes these light quantity data to calculate the average value, maximum value, minimum value, etc. of the light quantity transmitted through the slit 34, and the output of the ultraviolet light LED based on this value. By feeding back the level, the input current of the ultraviolet LED can be adjusted to maintain a constant irradiation intensity. Similarly, the average value, the maximum value, the minimum value, etc. of the output that does not include the ultraviolet light transmitted through the UV blocking filter film 30 are calculated, so that the fluorescent output of the fluorescent material such as ink or thread on the medium S can be accurately obtained. It becomes possible to measure.
In addition to improving the accuracy of discrimination by measuring the amount of fluorescence with high accuracy, it is possible to select and collect the medium S that is aged or contaminated with a detergent or the like. Further, by determining a current value necessary to ensure a certain irradiation intensity, the performance life of the light emitting element 29 can be detected, and the user can be notified of the replacement time.

  Although the embodiments of the present invention have been described above, the embodiments of the present invention are not limited to the above-described embodiments. For example, in addition to the configuration of receiving reflected light that is irradiated from the ultraviolet LED light source to the medium and reflected from the medium at a predetermined angle, an ultraviolet LED is attached to the light source 21 and the medium S is irradiated from the ultraviolet LED light source. A configuration in which the transmitted ultraviolet light transmitted through the medium S is received by the sensor light receiving unit through the rod lens array may be employed.

<Example 1>
As a rod lens array, Nippon Sheet Glass SELFOC lens SLA12B was adopted. An aluminum foil with a width of 10 mm is fixed to the end surface of the rod lens array at three positions on both ends and the center, and a band pass filter made of a multilayer film of titanium oxide and silicon oxide is cut from the top to form a bandpass filter. did. Then the aluminum foil was peeled off.

As a result, a rod lens array having slits that transmit ultraviolet light at only three locations was created. This rod lens array was assembled in a housing together with a sensor light receiving unit in which light receiving elements with a resolution of 200 dpi (dots per inch) were arranged.
Furthermore, an ultraviolet LED light source in which 15 UV LED elements (peak wavelength: 365 nm) made by Nichia are arranged in a straight line is prepared, and a single pulse bias current of 20 mA is adjusted to each element to obtain a constant ultraviolet light. Light was emitted and irradiated on a 20 euro banknote to observe the fluorescence pattern.

A graph of the amount of fluorescent light detected by the ultraviolet LED light source is shown in FIG. The horizontal axis represents the pixel position of the light receiving element, and the vertical axis represents the amount of fluorescent light (relative scale) detected by the sensor light receiving unit.
As shown in the figure, the amount of ultraviolet light that has passed through the slit (indicated by a in FIG. 4) is recorded, and the maximum value (indicated by b) and the minimum value (indicated by c) of the fluorescence output that has passed through the UV blocking filter film 30. Can be recorded). Of the fluorescence outputs (b, c) that have passed through the UV blocking filter film 30, b is the fluorescence output of the portion where the fluorescence is emitted, such as the flag portion and numbers, and c is the fluorescence of the base material portion (ground portion) of the medium S. Is the output. By using these values, for example, it is possible to determine the ratio of the light amount (bc) of the fluorescent part that has passed through the UV blocking filter film 30 with reference to the light amount (ac) that has passed through the slit, It is possible to determine the authenticity of the medium S and to determine the medium S in which the fluorescent part has worn due to aging. In addition, when contaminated with a detergent or the like, the output of the base material portion c can be determined as a contaminated medium S because the output is greatly increased by the fluorescence of the detergent.

If the values on the vertical axis in FIG. 4 are used, a−c = 727, b−c = 75, and the light amount ratio [(bc) / (ac −)) = 0.103, and the obtained numerical values are parameters. By managing it, it becomes possible to determine authenticity and to distinguish old and contaminated media S.
<Example 2>
In order to suppress the influence of the fluorescence of the paper substrate of the euro banknote, the fluorescence output was measured in the same manner as in Example 1 by changing the characteristics of the UV blocking filter film attached to the rod lens array to those having a cut characteristic of 450 nm or less. . The result is shown in FIG. The ratio of the amount of light (bc) transmitted through the UV blocking filter film, that is, the light amount ratio [(bc) / (ac)] with respect to the amount of light transmitted through the slit (ac) is 0. From 103 to 0.135. As a result, it was found that the contrast was increased and the detection capability was improved.

<Example 3>
When a bandpass filter film that cuts visible light of 400 nm or more was attached to the upper part of the LED element of the ultraviolet LED light source under the same conditions as in Example 2, and the characteristics were evaluated, the graph shown in FIG. 6 was obtained. .
According to this graph, the light quantity ratio [(bc) / (ac)] is 0.151, which is an effective measure for improving the detection capability and stabilizing the detection performance.

It is sectional drawing which shows the contact | adherence type | mold optical line sensor apparatus which detects the image of medium S, such as securities and a banknote. 4 is a perspective view of a rod lens array 23. FIG. 4 is an enlarged partial view of the rod lens array 23 showing an enlarged end surface of a sensor light receiving unit 24. FIG. It is the graph of the light quantity of fluorescence which assembled the rod lens array which has the slit which permeate | transmits ultraviolet light in the both ends and center of a UV blocking filter film | membrane in a housing | casing, and irradiated the ultraviolet light to the euro banknote and observed the fluorescence pattern. It is the graph which changed the characteristic of the UV blocking filter film into the thing of the characteristic of a cut of 450 nm or less, and measured the fluorescence output in order to suppress the influence of the fluorescence of the paper base material of a euro bill. It is the graph which measured the fluorescence output by mounting | wearing the LED element upper part with the band pass filter which cuts visible light of 400 nm or more in order to eliminate the influence of the visible light component emitted from the ultraviolet LED light source itself.

DESCRIPTION OF SYMBOLS 12, 13 Detection unit 22 Ultraviolet light LED light source 23 Rod lens array 24 Sensor light-receiving part 28 Visible light cut filter layer 30 UV cut filter film 33 Signal processing part 34 Slit S Media, such as securities and banknotes

Claims (7)

In the contact-type optical line sensor device that detects the fluorescence of the fluorescent material embedded in the medium by irradiating the medium with ultraviolet light,
An ultraviolet LED light source for irradiating ultraviolet light;
A light receiving element that receives the reflected light reflected from the medium by the ultraviolet LED light source and reflected from the medium at a predetermined angle or transmitted light transmitted through the medium;
A rod lens array provided in an optical path from the ultraviolet LED light source to the light receiving element;
In any one of optical paths from the ultraviolet LED light source to the light receiving element, a filter film that blocks ultraviolet light emitted from the ultraviolet LED light source is installed,
A contact-type optical line sensor device, wherein one or a plurality of slits that transmit ultraviolet light is provided in a part of the filter film.   The contact type optical line sensor device according to claim 1, wherein at least two slits are provided.   The contact optical line sensor device according to claim 1, wherein the filter film has a characteristic of blocking visible light and ultraviolet light having a wavelength of 420 nm or less.   The contact-type optical line sensor device according to claim 3, wherein the filter film has a characteristic of blocking visible light and ultraviolet light having a wavelength of 450 nm or less.   The contact type optical line sensor device according to any one of claims 1 to 4, wherein a band-pass filter that cuts visible light having a wavelength of 400 nm or more is mounted on the ultraviolet LED light source.   The contact type optical line sensor device according to claim 1, wherein the filter film is provided on an end surface of the rod lens. A method of identifying valuable paper by irradiating a medium with ultraviolet light and detecting fluorescence of a fluorescent substance embedded in the valuable paper,
Using the contact optical line sensor device according to any one of claims 1 to 6, the medium is irradiated with the ultraviolet light from the ultraviolet LED light source,
The reflected light reflected at a predetermined angle from the medium or the transmitted light transmitted through the medium is received through the rod lens array provided in the optical path from the ultraviolet LED light source to the light receiving element,
A valuable paper surface identification method for detecting a light amount ratio of a fluorescence amount of a medium transmitted through the filter film to an ultraviolet light amount transmitted through the slit.

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