JP2020113270A - Image acquisition device, paper sheet processing device, bill processing device and image acquisition method - Google Patents

Abstract

To provide an image acquisition device, a paper sheet processing device, a bill processing device and an image acquisition method, which can acquire an image on which a feature of a paper sheet can be detected in an opaque part, and an image in which a feature of the paper sheet can be detected in a transparent part.SOLUTION: An image acquisition device includes: a light-receiving unit that receives first transmitted light in which first irradiation light having a first light quantity has transmitted through a paper sheet, to output a first image signal, and receives second transmitted light in which second irradiation light having a second light quantity has transmitted through the paper sheet, to output a second image signal; and an image generation unit that generates a first transmission image from the first image signal, and generates a second transmission image from the second image signal. The second light quantity is set to be lower than the first light quantity.SELECTED DRAWING: Figure 2

Description

The present invention relates to an image acquisition device, a paper sheet processing device, a banknote processing device, and an image acquisition method. More specifically, the present invention relates to an image acquisition device, a paper sheet processing device, a banknote processing device, and an image acquisition method suitable for detecting the characteristics of a paper sheet having a transparent portion.

Paper sheets such as banknotes (banknotes), gift certificates, and checks have various security features to prevent forgery. For example, the paper used for paper sheets is mainly made of vegetable fiber, but for the purpose of improving durability, water resistance, security, etc., paper made of synthetic fiber or synthetic resin is used. A polymer sheet, which is a sheet of, may be used. Banknotes made from polymer sheets are called polymer banknotes and are difficult to counterfeit.

An optical sensor such as an optical line sensor is usually used when collecting features such as the outer shape of a paper sheet and the presence or absence thereof. However, since the transparent portion transmits light emitted from the optical sensor, the paper having the transparent portion is used. The leaves may be required to be treated differently from ordinary paper leaves having no transparent portion.

For example, in Patent Document 1, one surface of a paper sheet is irradiated with light of different wavelengths from two different light sources, and light transmitted through the paper sheet by these light irradiations is received, thereby The optical reading device and the paper sheet processing device which realize the detection of the watermark image and the detection of the shape and the defect in the same stage are disclosed.

JP, 2013-77163, A

When an image of a paper sheet is used to identify the type, authenticity, etc. of the paper sheet, the image is usually captured by an image acquisition device including an optical line sensor. Transmits the light emitted from the light source of the image acquisition device, for example, infrared light. Therefore, also in this case, the paper sheet having the transparent portion is required to be processed differently from the ordinary paper sheet having no transparent portion.

Specifically, in the paper sheet identification process, first, it is necessary to detect (extract) the outer shape (contour) of the paper sheet from the image data based on the output of the optical line sensor. That is, the image based on the output of the optical line sensor is an image including not only the paper sheet but also the background (the area other than the paper sheet), but the area corresponding to the paper sheet is specified from the entire image. , It is necessary to extract the outer shape of the region. However, in the case of a paper sheet having a transparent portion, the area corresponding to the paper sheet may not be accurately extracted from the entire image.

For example, when a transparent image of a banknote is captured using infrared light in order to detect the characteristics of the ink of a banknote having a transparent part in the opaque part, the infrared light passes through the transparent part, and FIG. The transparent image 210 as shown is obtained, and in the medium area 211 corresponding to a bill, the transparent area 212 corresponding to the transparent portion may be assimilated with the background area 213 corresponding to the area other than the bill. This is because in order to detect the characteristics of the ink in the opaque area 214 corresponding to the opaque section, it is necessary to set the light amount of the light irradiated on the banknote to be high and to increase the output of the light receiving section of the optical line sensor. This is because the output of the light receiving part in the transparent part is saturated. In the case as shown in FIG. 8, there is a possibility that the bill may be erroneously recognized as a torn bill. Further, even if the transparent portion of the banknote has a shade pattern, since the transparent region 212 is a saturated region, the shade pattern cannot be detected from the transparent image 210 including the transparent region 212. Similarly, even if the transparent portion of the banknote has a defect, the transparent image 210 including the transparent region 212 cannot detect the defect of the transparent portion.

Further, as described in Patent Document 1, even when light having different wavelengths is applied to a paper sheet having a transparent portion, only various kinds of light having different wavelengths are transmitted, so It is not possible to accurately detect the outer shape and presence/absence, and it is also impossible to accurately detect the shade pattern or the defect of the transparent portion. For example, when the banknotes are irradiated with visible light and infrared light with a light amount capable of detecting the characteristics of the ink in the opaque part, the output of the light receiving part is saturated in both cases in the transparent part with high transmittance. Therefore, the outer shape cannot be detected.

As described above, conventionally, by using an image of a paper sheet, the shape and presence/absence of the paper sheet, the characteristics of the ink, the characteristics of the paper sheet such as the light and shade pattern and the defect are not limited to the opaque portion but the transparent portion. There was room for improvement in terms of detection.

The present invention has been made in view of the above circumstances, and an image capable of acquiring an image capable of detecting the characteristics of a paper sheet in an opaque portion and an image capable of detecting the characteristics of a paper sheet in a transparent portion. An object is to provide an acquisition device, a paper sheet processing device, a banknote processing device, and an image acquisition method.

In order to solve the above-described problems and achieve the object, the present invention is an image acquisition device, which is a light source that irradiates a sheet with light, and a first light amount of a first light amount emitted from the light source. The irradiation light receives the first transmitted light transmitted through the paper sheet and outputs the first image signal, and the second irradiation light of the second light amount emitted from the light source is the paper sheet. A light-receiving unit that receives the second transmitted light that has passed through the second image signal and outputs a second image signal, and a first transmitted image is generated from the first image signal, and a second transmitted image is generated from the second image signal. And an image generation unit that generates a transmission image of the second light amount, and the second light amount is set to be smaller than the first light amount.

Further, in the present invention, in the above-mentioned invention, the first light amount is set to a light amount including a saturated region in the first transmission image, and the second light amount is set in the second transmission image in the second transmission image. It is characterized in that a region corresponding to the saturated region is set to a light amount that does not saturate.

Further, the present invention is characterized in that, in the above invention, the saturated region is a region where an output of an image signal has a maximum value, and the unsaturated light amount is a light amount at which an output of the image signal becomes less than a maximum value. And

Further, in the present invention according to the above-mentioned invention, the image acquisition device further includes a control unit that controls the light source and the image generation unit, and the control unit is configured such that the first irradiation light and the second irradiation light periodically. The light source is controlled so as to irradiate the first and second irradiation lights at a timing such that they are sequentially irradiated, and the irradiation is synchronized with the timing of the irradiation of the first and second irradiation lights. Then, the image generating unit is controlled so that the first and second image signals are read from the light receiving unit.

Further, in the invention, in the above invention, the light receiving unit receives light emitted from the light source and outputs a third image signal in a state where the paper sheet does not exist, and the image generating unit is A reference waveform is generated from the third image signal, and the second light amount is set so that the reference waveform satisfies a predetermined condition.

Further, in the invention, in the above invention, the light receiving unit receives the light emitted from the light source and transmitted through a reference medium and outputs a fourth image signal, and the image generating unit is configured to output the fourth image signal. A reference medium waveform is generated from the image signal of No. 4, and the first light amount is set based on the transmittance of the reference medium calculated from the reference medium waveform.

Further, the present invention is characterized in that, in the above-mentioned invention, the first light amount is set so that a transmittance of the entire reference medium is constant.

Further, in the invention, in the above invention, the paper sheet is a banknote, a gift certificate, or a check having a transparent portion, and the image generating unit generates a transparent image including an image of the transparent portion. And

Further, the present invention is characterized in that, in the above-mentioned invention, the transparent portion is a portion which exhibits a transmittance of 30 to 90% when irradiated with the first irradiation light.

Further, the present invention is characterized in that the light source irradiates the paper sheet with infrared light.

Further, the present invention is characterized in that the ratio of the second amount of light to the first amount of light is in the range of 1/16 to 1/4.

Further, the present invention is characterized in that the light source irradiates the paper sheet with visible light.

Further, the present invention is a paper sheet processing apparatus including the image acquisition device.

Further, the present invention is a banknote processing device including the image acquisition device.

Further, the present invention is an image acquisition method, wherein the first irradiation light of the first light amount emitted from the light source receives the first transmitted light that has passed through the paper sheet and receives the first image signal. And a light receiving step of outputting a second image signal by receiving the second transmitted light in which the second irradiation light of the second light amount emitted from the light source has transmitted through the paper sheet. An image generation step of generating a first transmission image from the first image signal and a second transmission image from the second image signal, wherein the second light amount is the first It is characterized in that it is set to be smaller than the light quantity of.

According to the image acquisition device, the paper sheet processing device, the banknote processing device, and the image acquisition method of the present invention, it is possible to detect the features of the paper sheet in the transparent portion together with the image in which the features of the paper sheet can be detected in the opaque portion. It is possible to acquire various images.

It is a plane schematic diagram which shows an example of the banknote which has a transparent part, (a) shows a front surface, (b) shows a back surface. It is a figure for demonstrating the outline of Embodiment 1, (a) is a schematic diagram which shows an example of the transparent image of the banknote obtained by irradiating the light of comparatively large light quantity, (b) is a figure. FIG. 6 is a schematic diagram showing an example of a transparent image of a bill obtained by irradiating a relatively small amount of light. It is a perspective schematic view showing the appearance of the banknote handling machine according to the first embodiment. It is a cross-sectional schematic diagram explaining the structure of the imaging part with which the banknote identification apparatus (image acquisition apparatus) concerning Embodiment 1 is equipped. It is a block diagram explaining the composition of the bill discriminating device (image acquisition device) concerning Embodiment 1. 6 is a timing chart showing an example of control of each light source by the light source control unit and control of signal reading from each line sensor by the sensor control unit in the first embodiment. 3 is a flowchart showing a procedure for acquiring a transmission image by infrared light in the banknote identification device (image acquisition device) and the image acquisition method according to the first embodiment. It is a schematic diagram which shows an example of the transparent image of a banknote. 6 is a timing chart showing an example of control of each light source by a light source control unit and control of signal reading from each line sensor by a sensor control unit in a modified embodiment according to the present invention.

Preferred embodiments of an image acquisition device, a paper sheet processing device, a banknote processing device, and an image acquisition method according to the present invention will be described below with reference to the drawings. Various paper sheets such as banknotes, checks, gift certificates, bills, forms, securities, and card-shaped media can be applied as the paper sheets to which the present invention is applied. That is, the banknote processing device is an aspect of the paper sheet processing device. In the following, the present invention will be described by taking an apparatus and method for banknotes as an example. In the following, as a preferred embodiment of the image acquisition device according to the present invention, a banknote identification device having a function of the image acquisition device will be described. The bill validating device may be a device that constitutes a part of the bill handling device, or may be an independent device that is not associated with the bill handling device. In addition, the following description is an example of a banknote identification device (image acquisition device), a banknote processing device, and an image acquisition method.

In the present specification, the reflection image means an image based on the intensity distribution of light reflected by the paper sheet by irradiating the paper sheet with light. Further, the transmission image means an image based on the intensity distribution of the light that is emitted by irradiating the paper sheet with the light.

<Banknotes to be processed>
First, the processing target of this embodiment will be described. The banknote to be processed is preferably a polymer banknote having a transparent portion such as a clear window that transmits the irradiated light, for example, infrared light or visible light. However, the present embodiment is also capable of processing banknotes that do not have a transparent portion, for example, paper banknotes. Among paper bills, a medium having a high transparency in the watermark portion and a medium having a high transparency such as an oil ticket are preferable. Since the synthetic resin (polymer) is suitable as the material of the transparent portion, it is preferable that the bill to be processed is formed of a polymer sheet. In addition, the banknote to be processed may be a banknote (hybrid banknote) in which the transparent portion is formed of a polymer sheet and the opaque portion is formed of paper made of plant fiber or synthetic fiber. As described above, the base material of the bill to be processed is preferably a polymer or a composite material of paper and polymer. An optically variable element (OVD) such as a rainbow hologram may be partially formed in the transparent portion.

FIG. 1 illustrates a banknote BN1 that is an example of a banknote to be processed. As shown in FIGS. 1(a) and 1(b), the banknote BN1 has a transparent portion BN1a provided in a strip shape at the center in the longitudinal direction and opaque portions BN1b provided on both sides of the transparent portion T1. ing. The transparent portion BN1a is, for example, an area having a transmittance of infrared light (for example, wavelength range: 760 to 1100 nm) of 30 to 90%, and a pattern is printed on each of the front surface and the back surface. The opaque portion BN1b is, for example, a region having a transmittance of infrared light of 10% or less, and a pattern such as a portrait or a price is printed on each of the front surface and the back surface. At least a part of each pattern of the transparent part BN1a and the opaque part BN1b is printed with infrared absorbing ink, and has a light and shade pattern including regions having different transmittances for infrared light.

<Outline of this embodiment>
Next, the outline of this embodiment will be described with reference to FIGS. Conventionally, when a transparent image of a banknote BN1 having a transparent portion BN1a is acquired, for example, as shown in FIG. 8, the output of the transparent region 212 corresponding to the transparent portion BN1a is saturated and blown out, and the transparent portion is transparent. In some cases, the characteristics of BN1a could not be acquired. This is because it is necessary to irradiate the banknote BN1 with light having a relatively large amount of light in order to extract the characteristics of the ink in the opaque portion BN1b.

Therefore, in the present embodiment, when acquiring the transmission image of the banknote BN1 having the transparent portion BN1a, the normal light amount of light (for extracting the characteristics of the ink) and the transmittance of 100% (without the medium) are used as in the conventional case. In the state), the banknote BN1 is irradiated with light whose light amount is reduced so that the output does not saturate (e.g., when the light is saturated at 255 digit when saturated, 200 digit), and two types of transmission images are acquired. As a result, as shown in FIG. 2A, the output of the transparent area 212 corresponding to the transparent portion BN1a is saturated and blown out by the former normal light amount, while the opaque portion BN1b is exposed. A transmission image 210 can be obtained in which the ink features are imaged in the corresponding opaque areas 214. Therefore, it is possible to detect the characteristics of the ink in the opaque portion BN1b and the presence/absence of a defect in the opaque portion BN1b from the transparent image 210. In addition, the latter small amount of light, as shown in FIG. 2B, does not saturate the output of the transparent region 222 corresponding to the transparent part BN1a, and acquires the transmission image 220 in which the characteristics of the transparent part BN1a are captured. You can Therefore, it is possible to prevent the transparent area 222 from assimilating with the background area 223 (area other than the medium area 221) corresponding to the area other than the banknote BN1 (area where the banknote BN1 does not exist), and the two opaque areas 224 (opaque part BN1b). ) Are connected, it is possible to accurately detect the outer shape of the medium area 221 corresponding to the banknote BN1. Further, from the transparent image 220, it is possible to detect the shade pattern of the transparent portion BN1a and the presence/absence of a defect in the transparent portion BN1a. In the latter transmission image 220, since the amount of light applied to the opaque portion BN1b is small, in the opaque region 224 corresponding to the opaque portion BN1b, the characteristic of the ink may not be captured, and blackening may occur. The transparent portion BN1a is preferably a portion that exhibits a transmittance of 30% or more with respect to the light emitted from the light source of the banknote identification device (image acquisition device) according to the present embodiment, for example, 30 to 90%. It may be a portion showing the transmittance of. When irradiating the opaque portion BN1b with a light amount that can extract the characteristics of the ink, if the transmittance of the transparent portion BN1a is 30% or more, the output may be saturated in the transparent region. However, as in the present embodiment. By using light with a small amount of light, it is possible to obtain a transmission image in which the output in the transparent area is not saturated. On the other hand, if the transmittance of the transparent portion BN1a exceeds 90%, the medium presence/absence threshold may not be drawn.

<Configuration of banknote processing device>
Next, the configuration of the banknote handling machine according to this embodiment will be described with reference to FIG. The banknote handling apparatus according to this embodiment may have the configuration shown in FIG. 3, for example. The banknote processing apparatus 300 shown in FIG. 3 is a small banknote processing apparatus installed on a table and used, and includes a banknote identification apparatus (not shown in FIG. 3) that performs banknote identification processing and a plurality of processing target objects. The hopper 301 on which the banknotes are stacked and the banknotes fed out from the hopper 301 into the housing 310 are reject banknotes such as counterfeit banknotes and uncertain banknotes. Two reject sections 302, an operation section 303 for inputting an instruction from an operator, and four operation sections 303 for classifying and accumulating banknotes whose denomination, authenticity, and damage are identified in the housing 310. The stacking units 306a to 306d and the display unit 305 for displaying information such as the identification and counting result of banknotes and the stacking status of each stacking unit 306a to 306d are provided. Of the four stacking units 306a to 306d, the stacking units 306a to 306c store the correct bills, and the stacking unit 306d stores the dirty bills, based on the result of the fitness judgment by the bill validator. The method of distributing the bills to the stacking units 306a to 306d can be set arbitrarily.

<Structure of imaging unit>
Next, with reference to FIG. 4, a configuration of an imaging unit which is a main part of the bill identifying device according to the present embodiment will be described. As shown in FIG. 4, the imaging unit 21 includes optical line sensors 110 and 120 arranged to face each other. A gap through which the bill BN is conveyed is formed between the optical line sensors 110 and 120, and this gap constitutes a part of the conveyance path 311 of the bill processing apparatus according to the present embodiment. The optical line sensors 110 and 120 are located above and below the conveyance path 311 respectively.

The optical line sensor 110 includes two reflection light sources 111, a condenser lens 112, and a light receiving unit 113. The reflection light source 111 has a predetermined wavelength of light (invisible light such as infrared light, monochromatic light such as red, green, blue, or white) on the main surface (hereinafter, referred to as A surface) of the bill BN on the light receiving unit 113 side. Visible light). The condenser lens 112 condenses the light emitted from the reflection light source 211 and reflected by the bill BN. The light receiving unit 113 includes a plurality of solid-state image pickup devices (not shown) arranged in a line in a direction (main scanning direction) orthogonal to the conveyance direction (sub scanning direction) of the bill BN, and the condenser lens 112. The light collected by is received and converted into an electric signal. Then, after the electric signal is amplified, it is A/D converted into digital data and output as an image signal.

The optical line sensor 120 includes two reflection light sources 121, a condenser lens 122, a light receiving section 123, and a transmission light source 124. The reflection light source 121 has a predetermined surface of light (invisible light such as infrared light, monochromatic light such as red, green, blue, or white) on the main surface (hereinafter, referred to as B surface) of the bill BN on the light receiving portion 123 side. Visible light). The condenser lens 122 condenses the light emitted from the reflection light source 121 and reflected by the bill BN. The light receiving unit 123 includes a plurality of solid-state image pickup devices (not shown) arranged in a line in a direction orthogonal to the conveyance direction of the bill BN, and receives the light condensed by the condenser lens 122. Convert to electrical signal. Then, after the electric signal is amplified, it is A/D converted into digital data and output as an image signal.

The transmissive light source 124 irradiates the surface B of the banknote BN with light of a predetermined wavelength (invisible light such as infrared light, monochromatic light such as red, green, blue, or visible light such as white light). The transmissive light source 124 is arranged on the optical axis of the condenser lens 112 of the optical line sensor 110, and a part of the light emitted from the transmissive light source 124 passes through the banknote BN and is transmitted to the optical line sensor 110. The light is condensed by the condenser lens 112 and detected by the light receiving unit 113.

Each of the light sources 111, 121, and 124 has a linear light guide (not shown) extending in a direction (main scanning direction) perpendicular to the paper surface of FIG. 4, and both end portions (one end portion) of the light guide. ) Is provided with a plurality of LED elements (not shown).

Each of the reflection light sources 111 and 121 includes, as an LED element, for example, a plurality of LED elements capable of irradiating light in different wavelength bands, and is configured to irradiate light in a selected wavelength band. Specifically, for example, each of the reflection light sources 111 and 121 includes an LED element that emits infrared light (IR) and an LED element that emits visible light (monochromatic light such as red, green, blue, or white). And irradiates the paper sheets with infrared light and visible light, respectively.

The transmissive light source 124 includes, for example, a plurality of LED elements capable of irradiating light in different wavelength ranges as LED elements, and is configured to irradiate light in a selected wavelength range. Specifically, for example, the transmissive light source 124 includes an LED element that emits infrared light (IR) and an LED element that emits visible light (monochromatic light such as red, green, blue, or white). And irradiates the paper sheets with infrared light and visible light, respectively.

Each of the optical line sensors 110 and 120 repeatedly captures an image of the bill BN conveyed in the conveying direction and outputs an image signal, whereby the bill identifying device according to the present embodiment displays an image of the entire bill BN. get. The bill identifying device according to the present embodiment acquires a reflection image of the A surface of the bill BN and a transmission image of the bill BN based on the output signal of the optical line sensor 110, and based on the output signal of the optical line sensor 120, the bill identification device. The reflection image of the B side of BN is acquired.

<Configuration of bill validator (image acquisition device)>
Next, the configuration of the banknote identification device (image acquisition device) according to the present embodiment will be described with reference to FIG. As shown in FIG. 5, the banknote identification device (image acquisition device) 1 according to the present embodiment includes a control unit 10, a detection unit 20, and a storage unit 30.

The control unit 10 includes a program for implementing various processes stored in the storage unit 30, a CPU (Central Processing Unit) that executes the program, various hardware controlled by the CPU, and an FPGA (Field). It is configured by a logic device such as a Programmable Gate Array). The control unit 10 controls each unit of the bill identifying apparatus 1 based on the signal output from each unit of the bill identifying apparatus 1 and the control signal from the control unit 10 according to the program stored in the storage unit 30. Further, the control unit 10 has the functions of the light source control unit 11, the sensor control unit 12, the image generation unit 13, the shape detection unit 14, and the identification unit 15 according to the program stored in the storage unit 30.

The detection unit 20 includes a magnetic detection unit 22, a thickness detection unit 23, and a UV detection unit 24, in addition to the above-described image pickup unit 21, along the banknote transport path. The imaging unit 21 images the banknote as described above and outputs an image signal (image data). The magnetic detection unit 22 includes a magnetic sensor (not shown) that measures magnetism, and detects the magnetism of the magnetic ink, security thread, or the like printed on the bill by the magnetic sensor. The magnetic sensor is a magnetic line sensor in which a plurality of magnetic detection elements are arranged in a line. The thickness detection unit 23 includes a thickness detection sensor (not shown) that measures the thickness of a bill, and the thickness detection sensor detects a tape, a double feed, or the like. The thickness detection sensor detects a displacement amount of a roller facing each other across the conveyance path when a bill passes, by a sensor provided in each roller. The UV detection unit 24 includes an ultraviolet irradiation unit (not shown) and a light receiving unit (not shown), and receives the fluorescence generated when the ultraviolet irradiation unit irradiates the banknote with ultraviolet rays and the ultraviolet ray that transmits the banknote. Detected by.

The storage unit 30 is composed of a nonvolatile storage device such as a semiconductor memory or a hard disk, and stores various programs and various data for controlling the bill validator 1. In the storage unit 30, the wavelength range of the light emitted from each of the light sources 111, 121, and 124 during one cycle of image capturing by the image capturing unit 21, the timing of turning on and off each of the light sources 111, 121, and 124, The value of the forward current flowing through the LED element of each light source 111, 121, 124, the timing of reading a signal from each optical line sensor 110, 120, and the like are stored as imaging parameters.

It should be noted that the one-cycle imaging means the wavelength range of the light emitted from each light source 111, 121, 124, the turning on and off of each light source 111, 121, 124, the value of the forward current flowing through each LED element, and signal reading. It refers to an imaging pattern for which the timing of execution and the like are set. An image of the entire banknote is acquired by continuously performing the imaging of one cycle as one cycle.

The light source control unit 11 performs dynamic lighting control for sequentially lighting the light sources 111, 121, and 124 in order to capture an image of an individual banknote by each of the light sources 111, 121, and 124. Specifically, the light source control unit 11 controls the turning on and off of each of the light sources 111, 121, and 124 based on the timing set in the imaging parameter. This control is performed using a mechanical clock that changes according to the bill transport speed and a system clock that is always output at a constant frequency regardless of the bill transport speed. Further, the light source control unit 11 sets the magnitude of the forward current flowing through each LED element based on the imaging parameter.

The sensor control unit 12 controls the timing of reading an image signal from each of the optical line sensors 110 and 120 based on the timing set in the imaging parameter, and synchronizes with the timing of turning on and off the light sources 111, 121, and 124. Then, the image signal is read from each line sensor. This control is performed using the mechanical clock and the system clock. Then, the sensor control unit 12 sequentially stores the read image signals in the ring buffer (line memory) of the storage unit 30.

The image generation unit 13 has a function of generating an image based on various signals related to banknotes acquired from the detection unit 20. Specifically, the image generation unit 13 first decomposes the data (image signal) stored in the ring buffer into data for each condition of light irradiation and light reception. Specifically, the received light intensity data of light reflected by irradiating visible light, the received light intensity data of light reflected by irradiating infrared light, and the received light intensity data of light transmitted by irradiating visible light. , Infrared light is radiated and decomposed into received light intensity data of the transmitted light. Then, the image generation unit 13 performs correction processing such as dark output cut, gain adjustment, and correction of bright output level according to the characteristics of each of the decomposed data to generate various images (image data) of the banknote. And stores it in the storage unit 30.

The shape detection unit 14 detects (extracts) the outer shape (contour) of the banknote based on the infrared transmission image A of the banknote, which will be described later, and details thereof will be described later. Further, the shape detection unit 14 outputs the banknote contour information (extracted partial image area) to the identification unit 15.

The identification unit 15 performs identification processing using various signals related to banknotes acquired from the detection unit 20. The identification unit 23 identifies at least a denomination and authenticity of a bill. The identification unit 15 may have a function of determining whether the bill is right or wrong. In that case, the identification unit 15 detects stains, folds, tears, and the like of the banknotes, and also detects the tape or the like attached to the banknotes based on the thickness of the banknotes so that the banknotes can be reused in the market. It has a function of determining which unfit note is not suitable for market distribution.

Moreover, when using the image of the banknote imaged by the imaging unit 21 in order to identify the denomination, the authenticity, the damage, etc., the identification unit 15 uses the outline information of the banknote obtained by the shape detection unit 14. For example, the identification unit 15 defines a medium area corresponding to a banknote as an identification target area in an entire image including a banknote and other areas based on the contour information of the banknote obtained by the shape detection unit 14, Image data in the area is divided into blocks and identification processing is performed by pattern matching or the like.

Further, the identifying unit 15 may detect a shade pattern of a transparent portion of a bill based on an infrared transmission image A described later in order to identify a denomination, authenticity, fitness, etc. You may detect the defect of a transparent part.

<Control method of light source and control method of signal reading from line sensor>
Next, the control of each light source by the light source control unit 11 and the control of signal reading from each optical line sensor 110, 120 by the sensor control unit 12 will be described with reference to FIG. Note that FIG. 6 shows the contents and timing of turning on the light source and reading the signal.

The light source control unit 11 irradiates the infrared light of the light amount a and the infrared light of the light amount b at a timing such that the infrared light of the light amount a and the infrared light of the light amount b are periodically and sequentially irradiated. In addition, it is configured to control each light source. Specifically, as shown in the upper part of FIG. 6, at the imaging position of the optical line sensor 110, the banknotes to be conveyed are irradiated with infrared light of a light amount a from the light source for transmission 124 during one cycle. Then, the transmissive light source 124 irradiates infrared light of a light amount b, the transmissive light source 124 irradiates visible light, the reflective light source 111 irradiates infrared light, and Visible light is emitted from the reflection light source 111. The light amount a and the light amount b correspond to the second light amount and the first light amount, respectively, and the infrared light of the light amount a and the infrared light of the light amount b are respectively the first irradiation light and the first irradiation light. It corresponds to the irradiation light of 2. While the banknote is being irradiated with light, each image pickup device of the light receiving unit 113 is exposed to accumulate electric charges. The sensor control unit 12 is configured to read the image signal from the light receiving unit 113 in synchronization with the irradiation timing of the infrared light of the light amount a and the infrared light of the light amount b. That is, every time the light applied to the bill is switched, the image signal of the light before the switching is read from the optical line sensor 110. As a result, the optical line sensor 110 forms one line of data for forming a transmission image (hereinafter, infrared transmission image A) by the infrared light of the light amount a, and a transmission image by the infrared light of the light amount b (hereinafter, infrared transmission image A) in one cycle. Hereinafter, one line of data forming an infrared transmission image B), one line of data forming a transmission image by visible light (hereinafter, visible transmission image), a reflection image of the A surface by infrared light (hereinafter, One line of data forming the infrared reflection image of the A surface and one line of data forming the reflection image of the A surface by visible light (hereinafter, visible reflection image of the A surface) are acquired. Become.

By repeatedly performing this one-cycle imaging, the infrared transmission image A, the infrared transmission image B, the visible transmission image, the infrared reflection image of the A side, and the visible reflection image of the A side of the entire banknote are obtained. Get each. The infrared transmission image A and the infrared transmission image B correspond to the second transmission image and the first transmission image, respectively.

As shown in the lower part of FIG. 6, at the image pickup position of the optical line sensor 120, first, the reflection light source 121 is turned off for a predetermined period (a period in which light is emitted from the transmission light source 124 to the paper sheet) during one cycle. After that, the reflected light source 121 irradiates the conveyed banknotes with infrared light, and then the reflection light source 121 irradiates visible light. While the banknote is being irradiated with light, each image pickup device of the light receiving unit 123 is exposed to accumulate electric charges. Here again, every time the light applied to the bill is switched, the image signal of the light before the switching is read from the optical line sensor 120. As a result, by the optical line sensor 120, data for one line forming a reflection image of the B surface by infrared light (hereinafter, infrared reflection image of the B surface) in one cycle, and reflection of the B surface by visible light. Data for one line forming an image (hereinafter, a visible reflection image of the B surface) is acquired.

The infrared reflection image of the B surface and the visible reflection image of the B surface are respectively acquired by continuously and repeatedly performing this one-cycle imaging.

As shown in FIG. 6, the time for irradiating each type of light is set to be constant. That is, the charge accumulation time of each image sensor is set constant regardless of the type of light.

On the other hand, the light amount a is set to be smaller than the light amount b. The ratio of the light amount a to the light amount b can be set as appropriate, but is preferably in the range of 1/16 to 1/4.

In the present embodiment, the amount of light is represented by (the magnitude of the forward current of the LED element)×(irradiation time), and the irradiation time is constant as described above, and therefore flows into the LED element of the transmissive light source 124. The value of the forward current is set smaller when the infrared transmission image A is captured than when the infrared transmission image B is captured. Since the forward current of the LED element is proportional to the radiation intensity of the LED element, it can be said that the light amount is proportional to the radiation intensity of the LED element.

In addition, the light amount b includes a saturated region (whitened region) where the infrared transmission image B (more specifically, a medium region corresponding to a banknote in the infrared transmission image B, usually a transparent region corresponding to a transparent portion) is saturated. It is preferable that the light amount is set. Thereby, the feature of the bill, for example, the feature of the ink, can be detected from the infrared transmission image B in the opaque region corresponding to the opaque portion of the bill. In the infrared transmission image B, the entire transparent area may be the saturated area. The saturated area (whitened area) is an area where the output of the image signal becomes the maximum value. Specifically, dark output correction is performed on the outputs of the optical line sensors 110 and 120 so that the output when the light source is turned off is zero, and further, the output of the white reference medium when the light source is turned on is made constant. A region where the output of the image signal becomes a predetermined maximum value (for example, 255 digit) when the data for forming the transmission image is acquired in the absence of the white reference medium after performing the bright output correction for the pixel gain correction. Refers to.

On the other hand, it is preferable that the light amount a is set to a light amount that does not saturate the area corresponding to the saturated area of the infrared transmission image B in the infrared transmission image A (does not cause overexposure). Thereby, from the infrared transmission image A, it is possible to detect the features of the banknote, such as the outer shape and the light and shade pattern, and the presence/absence of a defect in the transparent part in the transparent region corresponding to the transparent part of the banknote. The light amount that does not saturate may be a light amount at which the output of the image signal is below the maximum value.

<Method of detecting outer shape of banknote>
Next, a method of detecting the outer shape of a bill by the shape detection unit 14 will be described. The shape detection unit 14 detects (extracts) the outer shape (outline) of the banknote based on the infrared transmission image A. That is, the medium area (partial image area) is specified from the entire infrared transmission image A including the medium area corresponding to the bill and the background area corresponding to the area other than the bill, and the outer shape of the area is detected.

More specifically, the shape detection unit 14 first binarizes the infrared transmission image A based on a predetermined threshold value. That is, each pixel value of the infrared transmission image A is compared with a predetermined threshold value, and if the pixel value is less than the threshold value, it is determined that the pixel exists, the pixel data is replaced with 1 (white), and the pixel value is If it is equal to or larger than the threshold value, the pixel is regarded as having no medium, and the pixel data is replaced with 0 (black). Subsequently, edge detection is performed on the binarized infrared transmission image A, and the four sides of the bill are detected from the results. Then, Hough transformation is performed to calculate straight lines passing through each side of the bill, and four vertices corresponding to the four corners of the bill are obtained.

In the present embodiment, the light amount a when acquiring the infrared transmission image A is smaller than the light amount b when acquiring the infrared transmission image B, and the infrared transmission image B is saturated in the infrared transmission image A. The amount of light that does not saturate the region corresponding to the region is set. That is, even if the infrared transmission image A is binarized, it is possible to determine that the transparent area corresponding to the transparent portion of the bill is present with the medium. Therefore, it is possible to prevent the transparent region in the infrared transmission image A from being blown out and being combined with the background region. As a result, the outer shape of the bill can be detected in the transparent region as well as the opaque region corresponding to the opaque portion of the bill.

<Image acquisition method>
Next, a process performed by the bill validator 1, and in particular, a method of acquiring the infrared transmission images A and B of the bill will be described. Here, first, a method of setting the light amounts a and b, that is, a method of initial adjustment of the transmissive light source 124 will be described.

The light amount a is preferably set as follows. That is, the transmissive light source 124 is caused to emit light in a state where a medium such as a banknote is not arranged at the imaging position of the optical line sensor 110. Then, the light (for example, infrared light) emitted from the transmissive light source 124 is received by the light receiving unit 113, and the image signal (one-dimensional data) corresponding to the third image signal is output. The image generator 13 also generates a reference waveform from this image signal. Then, the light amount a is set so that this reference waveform satisfies a predetermined condition.

The predetermined condition can be set as appropriate according to the characteristics of the medium to be imaged. For example, the maximum value of the reference waveform is set to 200 digit (saturation is 255 digit, 200 digit is transmittance: 100%). The light amount a may be adjusted by adjusting the magnitude of the forward current of the LED element and the irradiation time, and correction processing (dark output cut, gain adjustment, correction of bright output level, etc.) may be performed.

Further, the light amount a may be calculated from the waveform obtained in a state in which the reference medium having a lower transmittance than the transparent portion of the bill to be imaged is arranged at the image pickup position of the optical line sensor 110.

The light quantity b is preferably set as follows. That is, the transmissive light source 124 is caused to emit light in a state in which the entire white reference medium is arranged at the imaging position of the optical line sensor 110. Then, the light (for example, infrared light) emitted from the transmissive light source 124 is received by the light receiving unit 113, and an image signal (one-dimensional data) corresponding to the fourth image signal is output. The image generator 13 also generates a reference medium waveform from this image signal. Then, the transmittance of the reference medium is calculated from the waveform of the reference medium, and the light amount b is set based on the calculated transmittance of the reference medium. As a specific setting method of the light amount b, it is possible to make the transmittance of the entire reference medium constant. For example, when 255 digits shows saturation, the maximum value of the reference medium waveform is about 1 of 255 digits. The magnitude of the forward current of the LED element and the irradiation time may be adjusted so as to be about 128, which is /2. In order to prevent the output from being saturated at the light amount b, the output of the image signal may be adjusted so that the maximum value of the reference medium waveform becomes 4/5 times after adjusting the LED element.

Next, the acquisition processing of the infrared transmission images A and B of the bill by the bill identifying device 1 will be described with reference to FIG. 7. As shown in FIG. 7, first, the light receiving unit 113 receives the light of the light amount a emitted from the transmissive light source 124 that has passed through the banknote and outputs the image signal S1, and also emits the light from the transmissive light source 124. The light of the thus-obtained light amount b is transmitted through the bill, and the image signal S2 is output (S11). Here, the light amount a is set to be smaller than the light amount b. It should be noted that the light having the light amount a transmitted through the banknote and the light having the light amount b transmitted through the banknote correspond to the second transmitted light and the first transmitted light, respectively, and correspond to the image signal S1 and the image. The signal S2 corresponds to the second image signal and the first image signal, respectively.

Next, the sensor control unit 12 reads the image signals S1 and S2 from the optical line sensor 110, and sequentially stores the read image signals S1 and S2 in the ring buffer of the storage unit 30 (S12).

Then, the image generation unit 13 generates the infrared transmission image A from the data based on the image signal S1, and generates the infrared transmission image B from the data based on the image signal S2 (S13).

As described above, the light amount b is set to the light amount including the saturated region in the infrared transmission image B, and the light amount a is the light amount in which the region corresponding to the saturation region in the infrared transmission image A is not saturated. It is set.

As described above, in the present embodiment, the light receiving unit 113 receives the light of the light amount a emitted from the transmissive light source 124 that has passed through the banknote and outputs the image signal S1, and also the transmissive light source 124. The light of the light quantity b emitted from the banknotes receives the light transmitted through the bill to output the image signal S2, and the image generation unit 13 generates the infrared transmission image A from the image signal S1 and outputs the red image from the image signal S2. An outer transparent image B is generated. Here, the light amount a is set to be smaller than the light amount b, and preferably, the light amount b is set to the light amount including the saturated region in the infrared transmission image B, and the light amount a in the infrared transmission image A is The amount of light that does not saturate the region corresponding to the saturated region is set. Therefore, the features of the opaque portion of the bill can be detected from the infrared transmission image B, and the features of the transparent portion of the bill can be detected from the infrared transmission image A.

In the above-described embodiment, the time for irradiating each type of light (that is, the time for receiving each type of light and accumulating charges in each image sensor) is set so that the light amount a becomes smaller than the light amount b. The case where the value of the forward current flowing through the LED element of the transmissive light source 124 is changed while setting the constant value has been described, but these times may be different from each other. Specifically, the time for irradiating the banknote with light from the transmissive light source 124 is set to be shorter when the infrared transmission image A is captured than when the infrared transmission image B is captured. The value of the forward current flowing through the LED element of the transmissive light source 124 may be the same at times. Further, when the infrared transmission image A is captured, the time during which the banknotes are irradiated with light from the transmission light source 124 is shorter than when the infrared transmission image B is captured, and the bills flow to the LED elements of the transmission light source 124. The value of forward current may be small.

Further, in the above-described embodiment, the case where the light emitted with the light amount a and the light amount b is infrared light has been described, but the light emitted with the light amount a and the light amount b are red, green, blue, etc., respectively. It may be visible light. When green light is emitted, the ratio of the light amount a to the light amount b can be set as appropriate, but is preferably in the range of 1/16 to 1/4. Thus, the ratio of the light amount a to the light amount b may be different depending on the wavelength range used. Further, the magnitudes of the respective light quantities a and b may be different depending on the wavelength range used.

Here, referring to FIG. 9, when the light emitted with the light amount a and the light amount b is visible light, the light source control unit 11 controls each light source and the sensor control unit 12 each optical line sensor 110, 120. The control of signal reading from will be described. Note that FIG. 9 shows the content and timing of lighting the light source and reading the signal, and is the same as the case of FIG. 6 except that the content and timing of lighting the light source are partially different.

In the case shown in FIG. 9, as shown in the upper part of FIG. 9, at the image pickup position of the optical line sensor 110, the banknotes to be conveyed are irradiated with visible light of a light amount a from the transmissive light source 124 during one cycle. Then, the visible light of the light amount b is emitted from the transmission light source 124, the infrared light is emitted from the transmission light source 124, the infrared light is emitted from the reflection light source 111, and Visible light is emitted from the reflection light source 111. As a result, the optical line sensor 110 forms one line of data for forming a transmission image with visible light of a light amount a (hereinafter, visible transmission image A) in one cycle, and a transmission image with a visible light of light amount b (hereinafter, visible image). Data for one line forming a transmission image B), data for one line forming a transmission image by infrared light (hereinafter referred to as an infrared transmission image), one line forming an infrared reflection image of the A surface The data and the data for one line forming the visible reflection image of the A surface are acquired.

By repeatedly performing this one cycle of imaging, a visible transmission image A, a visible transmission image B, an infrared transmission image, an infrared reflection image of the A side, and a visible reflection image of the A side of the entire banknote are respectively obtained. get. The visible transparent image A and the visible transparent image B correspond to the second transparent image and the first transparent image, respectively.

As shown in the lower part of FIG. 9, imaging by the optical line sensor 120 is the same as that shown in FIG.

As shown in FIG. 9, the time for irradiating each type of light is set to be constant. That is, the charge accumulation time of each image sensor is set constant regardless of the type of light.

On the other hand, the light amount a is set to be smaller than the light amount b. The ratio of the light amount a to the light amount b can be set as appropriate, but as described above, when irradiating green light, the ratio of the light amount a to the light amount b is in the range of 1/16 to 1/4. Is preferred.

In the case shown in FIG. 9 as well, as in FIG. 6, the light amount b is a saturated region where the visible transmission image B (more specifically, a medium region corresponding to a banknote in the visible transmission image B, usually a transparent region corresponding to a transparent portion) is saturated. It is preferable that the light amount is set to include the (whitened area). Thereby, the features of the bill, for example, the features of the ink, can be detected from the visible transmission image B in the opaque region corresponding to the opaque portion of the bill. In the visible transparent image B, the entire transparent area may be a saturated area.

Further, it is preferable that the light amount a is set to such a light amount that the region corresponding to the saturated region of the visible transmission image B in the visible transmission image A is not saturated (not blown out). Thereby, from the visible transparent image A, it is possible to detect the characteristics of the banknote, such as the outer shape and the light and shade pattern, and the presence/absence of a defect in the transparent part, in the transparent region corresponding to the transparent part of the banknote.

Further, in the above embodiment, the case where the light emitted with the light amount a and the light emitted with the light amount b have the same wavelength range has been described, but the wavelength regions of the light emitted with the light amount a and the light amount b may be different from each other. ..

Moreover, in the said embodiment, the shape detection part 14 detects the outer shape of a banknote as the characteristic of a banknote based on the infrared transmission image A acquired by small light amount a, and the identification part 15 detects the characteristic of a banknote. The case of detecting the shade pattern of the transparent part and the loss of the transparent part has been described, but the banknote identification device (image acquisition device) 1 detects the presence or absence of a banknote based on the infrared transmission image A or the visible transmission image A. May be. Thereby, even if the transparent portion is located on the end surface of the bill, the bill identifying device 1 can detect the end portion as described above, and thus can accurately detect passage of the bill. In this way, the banknote identification device (image acquisition device) 1 can also be suitably used as a passage sensor that detects the presence or absence of a banknote being conveyed.

Although the embodiments of the present invention have been described above with reference to the drawings, the present invention is not limited to the above embodiments. In addition, the configurations of the respective embodiments may be appropriately combined or changed without departing from the scope of the present invention.

INDUSTRIAL APPLICABILITY As described above, the present invention is a technique useful for acquiring an image in which the features of paper sheets can be detected in the opaque portion and an image in which the features of paper sheets can be detected in the transparent portion.

1: bill validator (image acquisition device)
10: control unit 11: light source control unit 12: sensor control unit 13: image generation unit 14: shape detection unit 15: identification unit 20: detection unit 21: imaging unit 22: magnetic detection unit 23: thickness detection unit 24: UV detection Part 30: storage part 110, 120: optical line sensor 111, 121: reflection light source 112, 122: condensing lens 113, 123: light receiving part 124: transmission light source 210, 220: transmission image 211, 221: medium area 212 222: transparent areas 213, 223: background area 214, 224: opaque area 300: banknote processing device 301: hopper 302: reject section 303: operation section 305: display sections 306a to 306d: stacking section 310: housing 311: transport Road BN, BN1: Banknote BN1a: Transparent part BN1b: Opaque part

Claims (15)

A light source that irradiates paper sheets with light,
The first irradiation light of the first light amount emitted from the light source receives the first transmitted light transmitted through the paper sheet and outputs the first image signal, and the first irradiation light emitted from the light source A light-receiving unit that receives the second transmitted light, which has the second light amount of 2 and has passed through the paper sheets, and outputs a second image signal;
An image generation unit that generates a first transmission image from the first image signal and generates a second transmission image from the second image signal;
The image acquisition device according to claim 1, wherein the second light amount is set to be smaller than the first light amount. The first light amount is set to a light amount including a saturated region in the first transmission image,
The image acquisition apparatus according to claim 1, wherein the second light amount is set to a light amount that does not saturate a region corresponding to the saturated region in the second transmission image. The saturation region is a region where the output of the image signal becomes the maximum value,
The image capturing apparatus according to claim 2, wherein the light amount that does not saturate is a light amount that makes an output of an image signal less than a maximum value. The image acquisition device,
Further comprising a control unit for controlling the light source and the image generation unit,
The control unit is
While controlling the light source so as to irradiate the first and second irradiation light at a timing such that the first and second irradiation light are cyclically and sequentially irradiated,
It is configured to control the image generation unit so as to read the first and second image signals from the light receiving unit in synchronization with the timing of irradiation of the first and second irradiation lights. The image acquisition apparatus according to claim 1, wherein the image acquisition apparatus is an image acquisition apparatus. The light receiving unit receives light emitted from the light source and outputs a third image signal in a state where the paper sheet does not exist,
The image generator generates a reference waveform from the third image signal,
The image acquisition device according to claim 1, wherein the second light amount is set so that the reference waveform satisfies a predetermined condition. The light receiving unit receives the light emitted from the light source that has passed through a reference medium and outputs a fourth image signal,
The image generator generates a reference medium waveform from the fourth image signal,
The image acquisition apparatus according to claim 1, wherein the first light amount is set based on the transmittance of the reference medium calculated from the reference medium waveform. The image acquisition device according to claim 6, wherein the first light amount is set so that the transmittance of the entire reference medium is constant. The paper sheet is a banknote having a transparent portion, a gift certificate or a check,
The image acquisition device according to claim 1, wherein the image generation unit generates a transparent image including the image of the transparent unit. The image acquisition apparatus according to claim 8, wherein the transparent portion is a portion that exhibits a transmittance of 30 to 90% when irradiated with the first irradiation light. The image acquisition apparatus according to claim 1, wherein the light source irradiates the paper sheet with infrared light. The image acquisition device according to claim 1, wherein a ratio of the second amount of light to the first amount of light is in a range of 1/16 to 1/4. The image acquisition apparatus according to claim 1, wherein the light source irradiates the paper sheet with visible light. A paper sheet processing apparatus comprising the image acquisition apparatus according to claim 1. A banknote processing device comprising the image acquisition device according to claim 1. The first irradiation light of the first light amount emitted from the light source receives the first transmitted light transmitted through the paper sheet and outputs the first image signal, and the second light emitted from the light source is received. A light-receiving step of receiving the second transmitted light, which is the second irradiation light having the light amount of, and outputting the second image signal,
An image generating step of generating a first transparent image from the first image signal and generating a second transparent image from the second image signal,
The image acquisition method, wherein the second light amount is set to be smaller than the first light amount.

Images