JPH1137740A - Damage detecting device for paper sheets - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a damage detecting device for paper sheets wherein, by efficiently projecting parallel light from a light source, damage detection is performed with precision based on glossiness based on roughness of the surface of paper sheets. SOLUTION: Recessed parts of inverted truncated cone shape are provided on a substrate surface at specified intervals, an LED is allocated on the bottom part of each recessed part, and parallel light is emitted from a light source having a diaphragm and a reflection mechanism with a spherical mold lens on the recessed part. The parallel light is made incident on a bill 14 at angle of polarization at a sensor group 12, and p-polarization component and s- polarization component of the regular reflection light are photo-detected with a CCD1 and a CCD2, respectively, and a detection processing part performs damage detection for the bill 14 based on the p/s image.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting damage in a sheet processing machine such as a banknote counting and sorting machine.
The present invention relates to a paper sheet damage detection device that irradiates light to paper sheets and detects the degree of damage to the paper sheets based on the ratio between the p-polarized component and the s-polarized component of the specularly reflected light.

[0002]

2. Description of the Related Art Conventionally, there has been known a technique for detecting the degree of damage to paper sheets by utilizing the scattering directivity of reflected light.

[0003] For example, Japanese Patent Application Laid-Open No. 64-13695 discloses a first light receiving device that receives specularly reflected light of a light emitted from a light source on a bill surface.
A damaged bill discriminating device comprising a light receiving element and a second light receiving element for receiving diffusely reflected light on the bill surface, and comparing a ratio of the second light receiving element to the output of the first light receiving element with a predetermined set value. Is disclosed.

However, when using the scattered directivity characteristics of the reflected light, since the fluctuation of the inclination of the surface of the paper sheet and the change of the posture such as the vertical movement of the paper sheet with respect to the conveying path are large, the scattering directivity due to damage is large. It becomes difficult to detect a characteristic change.
For this reason, recently, attention has been focused on a technique for detecting damage from the glossiness due to the roughness of the sheet surface using the ratio of the p-polarized component and the s-polarized component of the specularly reflected light.

For example, Japanese Patent Application Laid-Open No. 63-52284 discloses that a light beam is obliquely incident on a bill and the ratio of the parallel polarization component (p-polarization component) and the vertical polarization component (s-polarization component) of the reflected light. And a bill sorting device configured to detect the presence or absence of the adhesive tape on the bill surface.

Japanese Patent Application Laid-Open No. Hei 8-219730 discloses that a light emitted from a light source is irradiated on a paper sheet with a vibrating surface aligned in a predetermined direction. A configuration in which only the scattered light having a vibration surface in a direction different from that of the applied light is detected by the optical sensor, and the pass / fail determination is performed based on the detection signal output from the optical sensor and the signal for the true paper sheets held in advance. The disclosed paper sheet quality discrimination device is disclosed.

[0007]

However, when such a conventional technique is used, there is a serious problem that damage to paper sheets cannot be detected accurately unless the spread angle of light emitted from the light source is narrow. is there.

To explain this point more specifically, as shown in FIG. 8, when a rod lens is arranged so that light emitted in the normal direction of the light source enters B point at Brewster's angle, In a plane formed by the central axis of the rod lens and the normal of the light source, a light ray emitted in a direction deviated from the normal direction of the light source by θ is applied to the bill at an incident angle η, and the specularly reflected light forms an image. The light is reflected in the direction of the angle φ formed with the system optical axis.

Therefore, for light emitted into the plane defined by the normal line of the light source and the center axis of the rod lens, θ = φ. If this φ is smaller than the aperture angle of the imaging lens, specular reflected light is formed. If the image is formed on the image plane, and φ is larger than the aperture angle of the imaging system lens, the specularly reflected light is not formed on the image forming plane, and only the scattered light is formed.

As a result, since the polarization of the scattered light is completely disturbed, it hardly depends on the roughness of the paper sheet surface. Since the ratio of the scattered light to the reflected light increases, the sensitivity to the state of the sheet surface decreases.

Therefore, in order to perform damage detection based on the glossiness due to the roughness of the paper sheet surface, it is necessary to make the irradiating light as parallel as possible. If it is used, it is not economical and only detection at a point is possible.

From these facts, an LED array is the most practical as an irradiation light source that is small, inexpensive and can irradiate a wide range, and a method of arranging LED chips on a flat substrate as shown in FIG. 9 is mainly used. .

However, if the LED is simply bonded to a flat substrate, the light emitted in an arbitrary direction propagates while spreading, so that φ is ideally 0 °.
Is the most desirable, as shown in FIG.
Will spread with a peak at about 30 °.

[0014] Then, by the spread of the irradiation light,
The reflected light from the paper sheet surface also spreads along the observation optical axis, and as a result, the light reaching the observation surface contains many scattering components, and the specular reflection component containing the roughness information of the paper sheet surface The ratio decreases, and an accurate specular reflected light component cannot be detected.

From these facts, when damage is detected from the glossiness due to the roughness of the paper sheet surface using the ratio of the p-polarized component and the s-polarized component of the specularly reflected light, Obtaining a good light source is an extremely important elemental technology.

In view of the above, the present invention solves the above-mentioned problems, and efficiently irradiates parallel light from a light source to accurately detect damage based on glossiness due to the roughness of the paper sheet surface. It is an object of the present invention to provide a kind of damage detection device.

[0017]

In order to achieve the above object, a first aspect of the present invention is to irradiate light to a paper sheet, and to illuminate the paper sheet based on a ratio of a p-polarized component and an s-polarized component of specularly reflected light. In the paper sheet damage detection device for detecting the degree of damage to the paper sheets, recesses having an inverted frustoconical shape are provided on the substrate surface at predetermined intervals, and LEDs are arranged at the bottom of each recess. A light emitting means having a provided aperture reflection mechanism, and the light emitted by the light emitting means is incident on the paper at a Brewster angle,
A light receiving unit that receives the p-polarized component and the s-polarized component of the specularly reflected light, and a ratio between the p-polarized component and the s-polarized component of the specularly reflected light received by the light-receiving unit, based on the obtained ratio. Detecting means for detecting the degree of damage to the paper sheet.

According to a second aspect of the present invention, the light emitting means has a spherical resin mold lens in an opening of the concave portion.

According to a third aspect of the present invention, the sheet is irradiated with light, and the degree of damage to the sheet is detected based on the ratio between the p-polarized component and the s-polarized component of the specularly reflected light. In the paper sheet damage detection device, an LED array in which LEDs are arranged at predetermined intervals on a substrate surface, and a black resin film in parallel with an incident surface on which the light emitted by the LED array enters the paper sheet. Light-receiving means for irradiating the light at a Brewster angle on the paper sheet through the disposed louver film and receiving a p-polarized component and an s-polarized component of the specularly reflected light,
P-polarized light component of the specularly reflected light received by the light receiving means and s
And a detecting means for detecting a degree of damage to the paper sheet based on the determined ratio, based on the determined ratio.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. In the present embodiment,
The case where the present invention is applied to a bill damage detecting device will be described.

FIG. 1 is a functional block diagram showing a configuration of a bill damage detecting device 10 used in the present embodiment.

As shown in FIG. 1, the bill damage detecting device 10 includes a light source 11, a sensor system 12, a detection processing unit 13
Consists of

The light source 11 has a mechanism (hereinafter referred to as an "aperture reflecting mechanism") for collimating the light emitted from the LED and narrowing the directivity thereof. Concave portions having a conical shape (a shape in which the head of a cone is cut and inverted) are provided at predetermined intervals, LEDs are arranged at the bottom of each concave portion, and a spherical resin mold is provided on the upper portion of the concave portion. By providing a lens, such a diaphragm reflection mechanism is realized.

The sensor system 12 irradiates light incident from the light source 11 on the bill 14 at an angle of Brewster's angle, receives the p-polarized component of the specularly reflected light by the CCD 1, and converts the s-polarized component into the CCD 2. To receive light.

The detection processing unit 13 detects the p received by the CCD 1
This is a processing unit that divides the polarization component by the s-polarization component received by the CCD 2 and detects the degree of damage to the bill 14 using the resulting p / s as an index.

As described above, in the bill detecting device 10,
Using the light source 11 capable of efficiently irradiating the parallel light, the banknote 1
4 is to detect damage based on glossiness due to surface roughness. The damage targeted for detection in the present embodiment is a paper fiber itself or its bond weakened due to aging, the hardness is lost, and the bill surface is roughened.

Next, a specific configuration of the light source 11 shown in FIG. 1 will be described.

FIG. 2 is a diagram showing an example of the configuration of the light source 11 shown in FIG.

As shown in FIG. 1, the light source 11 has recesses having a shape of an inverted frustoconical cone having a predetermined size at predetermined intervals on a substrate 20, and an LED 21 disposed on the bottom surface of each of the concave portions. It is composed. Note that the conical surface of the concave portion is plated with gold so as to function like a reflection mirror.

Here, in the present embodiment, the width of the opening of the concave portion is set to 1.3 mm, and the width of the bottom surface of the concave portion is set to 0.6 mm.
mm, the depth of the recess is 0.6 mm, and the angle formed by the conical surface from the opening of the recess toward the bottom surface with the bottom surface is 60 °.

For this reason, of the light emitted by the LED 21, the light emitted to the conical surface of the concave portion is reflected by the conical surface in the opening direction, and as a result, the spread of the light emitted by the LED 21 is suppressed. Is done.

FIG. 3 is a diagram showing the relationship between the amount of light and the angle φ between the reflected light and the imaging optical axis when the light source 11 shown in FIG. 2 is used. Here, the light amount is obtained by the ray tracing method using the directional characteristics obtained experimentally.

As shown in FIG. 3, when the light source 11 is used, the light amount becomes maximum when φ is about 0 °, and the angle φ
Is smaller than 30 °, the gloss distribution of the bill 14 can be accurately detected, and the bill 14
Damage can be detected.

Next, another configuration of the light source 11 shown in FIG. 1 will be described.

FIG. 4 is a diagram showing another configuration of the light source 11 shown in FIG.

As shown in the figure, the light source 11 is provided with a spherical resin mold lens 40 above a concave portion having an inverted frustoconical shape shown in FIG. As a result, a light source closer to parallel light can be formed.

That is, the resin mold lens 40
Plays a role of parallelizing the light emitted by the LED 21 and the light reflected by the conical surface forming the side wall of the concave portion.

Next, a specific configuration of the sensor system 12 shown in FIG. 1 will be described.

FIG. 5 is a block diagram showing a specific configuration of the sensor system 12 shown in FIG.

As shown in the figure, the unpolarized light emitted by the light source 11 is prevented from spreading in the direction perpendicular to the axis of the lens by the cylindrical rod lens 51 while the cover glass 5
The banknote 14 is irradiated at an incident angle of Brewster's angle via the cover glass 52 and the reflected light is transmitted through the cover glass 52 and the folding mirror 53 to form the selfoc lens array 5 for imaging.
4 is incident.

Thereafter, the light that has passed through the imaging Selfoc lens array 54 is split by the polarizing beam splitter 55, and the CCD 1 receives the p-polarized component of the specularly reflected light, and the CCD 2 receives the s-polarized component.

As described above, the sensor system 12 is configured to separately receive the p-polarized light component and the s-polarized light component of the specularly reflected light from the bill 14 and output the received light amount to the detection processing unit 13. I have.

Next, the configuration of the detection processing unit 13 shown in FIG. 1 will be described.

FIG. 6 is a diagram showing a hardware configuration of the detection processing unit 13 shown in FIG.

As shown in FIG.
Are amplifiers 61 and 62, a multiplexer 63, and A
It comprises a / D converter 64, a memory 65, and a CPU 66.

The light receiving outputs detected by the CCD 1 and the CCD 2 are amplified by the amplifiers 61 and 62, and are converted into time series data by the multiplexer 63.

The time-series data is A / D-converted by the A / D converter 64 and stored in the memory 65, so that the CPU 66 performs an arithmetic process based on the data stored in the memory 65.

More specifically, the CPU 66 comprises a CCD 1
Is divided by the s-polarized component image obtained from the CCD 2 to obtain a p-polarized component / s-polarized component image (hereinafter referred to as “p / s image”), and the p / s image is obtained. Is detected as a portion having a high degree of damage.

For example, the middle of a bill is folded many times,
In the case of a banknote whose central part is intensively damaged, p / s
A partial damage degree can be detected from a partial integration amount near the center of the image.

In the case of a banknote having a large damage as a whole, the pixel value of the p / s image becomes large as a whole, so that the degree of damage can be detected from the ratio with the total integrated amount of the new ticket held in advance. .

As described above, in the present embodiment,
An aperture reflecting mechanism in which concave portions having an inverted frustoconical shape are provided at predetermined intervals on the substrate surface, LEDs are provided at the bottom of each concave portion, and a spherical resin mold lens is provided above the concave portions. The parallel light is emitted from the light source 11 having the following formula, and the parallel light is incident on the bill 14 at the Brewster angle in the sensor system 12, and the p-polarized component of the specularly reflected light and s
Since the polarization components are received by the CCD 1 and the CCD 2, respectively, and the determination processing unit 13 is configured to detect the damage of the bill 14 based on the p / s image, the following effects can be obtained.

1) It is possible to obtain a light source that emits parallel light with good directivity with a simple configuration.

2) Damage detection based on glossiness due to the roughness of the surface of the bill 14 can be performed with high accuracy.

3) A small and inexpensive sensor system capable of stably detecting the degree of damage can be constructed.

In this embodiment, concave portions having an inverted frustoconical shape are provided at predetermined intervals on the substrate surface, LEDs are provided at the bottom of each concave portion, and a spherical surface is provided on the upper portion of the concave portion. Although the light source 11 having the aperture reflection mechanism provided with the resin mold lens described above is used, it is also possible to irradiate the banknote 14 with parallel light using a louver film.

FIG. 7 is a view showing the structure of the louver film. As shown in FIG. 7A, the louver film has a structure in which a thin black resin film and a transparent resin are arranged in multiple layers. As shown in FIG. 2B, light having a spread and emitted in a direction parallel to the black resin film is blocked at a certain angle or more determined by the gap between the black resin films and the thickness of the louver film.

For this reason, in the sensor system 12 shown in FIG. 5, the black resin film of the louver film and the axis of the rod lens 51 are arranged orthogonal to each other in the irradiation optical system until the light reaches the bill 14. Accordingly, it is possible to suppress the axial spread of the rod lens 51, and it is possible to irradiate the banknote 14 with light close to parallel light.

When such a louver film is used, since the light component having a spread is absorbed by the louver film, the irradiation light intensity is reduced as compared with the case where the aperture reflection mechanism is used. Similar to the damage detection device 10, damage detection based on the glossiness due to the surface roughness of the bill 14 can be performed with high accuracy.

[0059]

As described in detail above, the first aspect of the present invention provides concave portions having an inverted frustoconical shape on a substrate surface at predetermined intervals, and disposes LEDs at the bottom of each concave portion. Since the light emitting means having the aperture stop reflecting mechanism emits light, the following effects can be obtained.

1) Parallel light with good directivity can be obtained with a simple configuration.

2) Damage detection based on glossiness due to the roughness of the paper sheet surface can be accurately performed.

3) It is possible to construct a small and inexpensive sensor capable of stably detecting the degree of damage.

In the second aspect of the present invention, since a spherical resin mold lens is further provided at the opening of the concave portion, it is possible to acquire parallel light with even higher directivity.

In the third invention, the light emitted from the LED array is incident on the paper sheet via a louver film provided with a black resin film in parallel with the incident surface on which the light is incident on the paper sheet. With this configuration, it is possible to accurately detect damage based on the glossiness due to the roughness of the paper sheet surface.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing a configuration of a bill damage detection device used in the present embodiment.

FIG. 2 is a diagram showing an example of a configuration of a light source shown in FIG.

FIG. 3 is a diagram showing the relationship between the amount of light and the angle φ between the reflected light and the imaging optical axis when the light source shown in FIG. 2 is used.

FIG. 4 is a diagram showing another configuration of the light source shown in FIG.

FIG. 5 is a block diagram showing a specific configuration of the sensor system shown in FIG. 1;

FIG. 6 is a diagram illustrating a hardware configuration of a detection processing unit illustrated in FIG. 1;

FIG. 7 is a diagram showing a structure of a louver film.

FIG. 8 is a view showing the concept of a conventional sensor irradiation optical system.

FIG. 9 is a view showing the shape of a conventional LED substrate.

FIG. 10 is a diagram showing an intensity distribution of an angle φ formed by specular reflection light and an imaging optical axis when the LED substrate shown in FIG. 9 is used.

[Explanation of symbols]

1,2 ... CCD, 10 ... Billage damage detection device, 11 ...
Light source, 12: sensor system, 13: detection processing unit, 14 ...
Banknotes, 20 board, 21 LED, 40 resin mold lens, 51 rod lens, 52 cover glass, 53 folding mirror, 54 selfoc lens array, 55 polarizing beam splitter, 61, 62
Amplifier 63: Multiplexer 64: A / D converter 65: Memory 66: CPU

Claims (3)

[Claims] 1. Damage detection of a paper sheet which irradiates light to the paper sheet and detects a degree of damage to the paper sheet based on a ratio of a p-polarized component and an s-polarized component of the specularly reflected light. In the apparatus, light emitting means having an aperture reflecting mechanism in which concave portions having an inverted frustoconical shape are provided at predetermined intervals on the substrate surface, and LEDs are arranged at the bottom of each concave portion, and the light emitting means emits light. Light receiving means for receiving light at the Brewster's angle on the paper sheet and receiving a p-polarized component and an s-polarized component of the specularly reflected light, respectively, and a p-polarized component of the specularly reflected light received by the light receiving means. s
A sheet damage detecting device, comprising: a detection unit that obtains a ratio to a polarization component and detects a degree of damage to the sheet based on the obtained ratio. 2. The paper sheet damage detecting device according to claim 1, wherein said light emitting means has a spherical resin mold lens in an opening of said concave portion. 3. Damage detection of a paper sheet by irradiating the paper sheet with light and detecting a degree of damage to the paper sheet based on a ratio between a p-polarized component and an s-polarized component of the specularly reflected light. In the device, an LED array in which LEDs are arranged at predetermined intervals on a substrate surface, and a louver film in which a black resin film is arranged in parallel with an incident surface on which the light emitted by the LED array enters the paper sheet. Light receiving means for receiving the p-polarized component and the s-polarized component of the specularly reflected light of the light at the Brewster angle through the Brewster angle, respectively; Polarization component and s
A sheet damage detecting device, comprising: a detection unit that obtains a ratio to a polarization component and detects a degree of damage to the sheet based on the obtained ratio.