WO2009110064A1

WO2009110064A1 - Optical sensor and optical waveguide prism

Info

Publication number: WO2009110064A1
Application number: PCT/JP2008/053845
Authority: WO
Inventors: 孝明小西
Original assignee: グローリー株式会社
Priority date: 2008-03-04
Filing date: 2008-03-04
Publication date: 2009-09-11

Abstract

An optical sensor irradiates a light onto an object to be detected which is moving relatively to the sensor itself to detect a light from the object to be detected. The optical sensor includes a plurality of light sources for irradiating lights onto a plurality of separate locations on the object to be detected independently, a single optical receiver element to receive lights from a plurality of locations on the object to be detected for performing photoelectric conversion, and an optical waveguide section which transmits a light outgoing from each of a plurality of light sources for guiding to the object to be detected, while guiding lights from a plurality of locations to the single optical receiver element using each different reflective path.

Description

Optical sensor and light guide prism

The present invention relates to an optical sensor that irradiates light to a detected object such as a paper sheet or a card that moves relative to the sensor main body, and detects light from the detected object. The present invention relates to a configuration of an optical sensor that can detect information from a plurality of positions that are not in the vicinity of an object to be detected that moves relative to a main body. The present invention also relates to a light guide prism used in such an optical sensor.

Conventionally, for paper sheets such as gift certificates, securities, receivables, banknotes, cards such as prepaid cards, credit cards, etc., for example, the purpose of classifying them and whether they are genuine products For the purpose of making a determination (determining authenticity), a bar code is displayed on a part of it, or a part is printed with special ink. For such paper sheets, cards, and the like, it is common to classify or authenticate them using an optical method. Examples of the special ink include an ink that emits infrared rays (causes a fluorescent reaction) when irradiated with visible light, as disclosed in Patent Document 1, for example.

Examples of sensors that detect fluorescence generated from an object to be detected (such as paper sheets and cards) by an optical technique include optical sensors disclosed in

Patent Documents

2 and 3. FIG. 18 is a schematic diagram showing a configuration of an optical system of a conventional optical sensor. Note that FIG. 18 also shows a transport path for transporting an object to be detected for convenience of explanation.

As shown in FIG. 18, the conventional optical sensor 100 includes a light source 101, a first filter 102 that transmits only light having a specific wavelength out of light emitted from the light source 101, and a first filter 102. A light transmissive / reflective mirror 103 that transmits and reflects the light that has passed therethrough and applies light that is orthogonal to the transport path 110 that transports the object to be detected, and a light transmissive / reflective mirror 103 that is emitted from the light source 101. Fluorescence emitted from the object to be detected by irradiation of the light reflected by the light receiving element 104 is received between the light receiving element 104 that receives the light through the light transmitting / reflecting mirror, and between the light receiving element 104 and the light transmitting / reflecting mirror 103, And a second filter 105 that cuts light of a specific wavelength that passes through the first filter 102.

When the optical sensor 100 is configured in this way, the light to be detected is irradiated from the light source 101 to the object to be transported, and the fluorescence emitted from the object to be detected can be detected by the light receiving element 104. For this reason, the fluorescent substance which a to-be-detected object has can be detected, for example, it can be judged whether a gift certificate etc. are genuine or a fake (determination of authenticity).

By the way, it is desired to detect information on a plurality of locations of a detected object by irradiating light to a plurality of separated positions (a plurality of positions separated in a direction non-parallel to the transport direction) that is not in the vicinity of the detected object to be conveyed. There is a case. In such a case, conventionally, a plurality of optical sensors as described above are generally arranged. For example, Patent Document 4 shows a configuration in which a plurality of light sources arranged in a line and a plurality of light receiving elements are arranged.
US Pat. No. 6,985,607 JP 2002-197506 A JP 2003-296792 A JP 2000-307819 A

However, in the conventional method, if information is to be detected from a plurality of positions that are not in the vicinity of the object to be detected (a plurality of positions separated in a direction not parallel to the conveyance direction), it is necessary to increase the number of light sources and light receiving elements. There is. As the number of light sources and light receiving elements increases, the configuration of the electric circuit also becomes complicated. For this reason, when information is obtained from a plurality of positions that are not in the vicinity of the object to be detected, there is a problem that the cost increases.

The present invention has been made in view of the above problems, and is an optical that can detect information at a low cost from a plurality of positions that are not in the vicinity of an object to be detected that moves relative to the sensor body. The purpose is to provide sensors. Moreover, it aims at provision of the light guide prism used for such an optical sensor.

In order to achieve the above object, the present invention provides an optical sensor for irradiating light to a detected object that moves relative to the sensor body and detecting light from the detected object, A plurality of light sources for separately illuminating a plurality of remote positions, a single light receiving element that receives light from the plurality of positions of the detection object and performs photoelectric conversion, and each of the plurality of light sources A light guide unit that transmits light emitted from the plurality of positions and guides the light from the plurality of positions to the single light receiving element using different reflection paths. It is characterized by providing.

According to this configuration, the light from the plurality of positions away from the object to be detected can be guided to a single light receiving element by using different reflection paths. For this reason, when information is detected from a plurality of positions that are not in the vicinity of the detected object that moves relative to the sensor body, the number of light sources is plural, but the number of light receiving elements can be one. That is, the number of light receiving elements can be reduced as compared with the conventional configuration, and information can be detected at a low cost from a plurality of positions that are not in the vicinity of the object to be detected. Moreover, in this structure, it is the structure which guides the light from the several position of a to-be-detected object to a single light receiving element with a light guide part, The distance between several positions is changed freely by the design of a light guide part. It is possible.

In the above configuration, the light guide unit may be formed of a single member. According to this configuration, the number of parts of the light guide unit can be reduced, and the assembly work of the optical sensor becomes easy.

Further, as a more specific configuration of the above configuration, the single member is provided for each of the plurality of light sources and transmits a light emitted from the plurality of light sources, and the detection target. The light guide prism may include a plurality of total reflection surfaces for totally reflecting the light from the object.

According to this configuration, light from a plurality of positions of the detection target is guided to a single light receiving element using total reflection, and it is easy to reduce light loss. For this reason, it is easy to make classification and determination using an optical sensor accurate. Moreover, according to this structure, the light guide part can be produced by resin molding, and the cost required for producing the light guide part can be reduced. For this reason, it is easy to implement | achieve the structure which detects information at low cost from the several position which is not the vicinity of a to-be-detected object.

In the above configuration, the light guide section includes a plurality of mirrors, and the plurality of mirrors are incident on the plurality of first mirrors that transmit a part of incident light and reflect the remaining part. A plurality of second mirrors that reflect all of the light may be included. Even in this configuration, since the number of light receiving elements can be reduced, information can be detected at a low cost from a plurality of positions that are not in the vicinity of the detection object.

In the above configuration, the wavelength of light emitted from the light source may be different from the wavelength of light received by the single light receiving element. According to this configuration, for example, it is possible to provide an optical sensor capable of detecting the presence of special ink that emits fluorescence when irradiated with light.

As a more specific configuration of the above configuration, the light emitted from the light source may be visible light, and the light received by the single light receiving element may be infrared light.

In the above configuration, the plurality of light sources may emit light having different wavelengths. According to this configuration, it is possible to detect information with a single light receiving element for an object to be detected having different characteristics at a plurality of positions.

In the above configuration, the plurality of light sources may be alternately lit. According to this configuration, for example, it is possible to grasp which position the information is detected from among a plurality of positions of the detected object. In addition, when a plurality of light sources emit light having different wavelengths, information can be individually detected for each wavelength.

In the above configuration, the plurality of light sources and the single light receiving element may be disposed on the same side as viewed from the object to be detected. According to this configuration, the optical sensor can be easily downsized. It can also be used for objects to be detected such as cards that are difficult to transmit light.

Further, in the above configuration, the plurality of light sources includes two light sources, a first light source and a second light source, the light guide prism is formed of resin, and the first light source and the light guide prism Between the second light source and the light guide prism, and between the light guide prism and the single light receiving element, a filter that restricts light that can pass through to the light of a specific wavelength region. May be arranged.

In order to achieve the above object, the light guide prism of the present invention functions as a light exit surface and an entrance surface, and has a plurality of entrance / exit surfaces on the same plane, and the plurality of entrance / exit surfaces. And a plurality of first inclined surfaces that function as total reflection surfaces, and are provided for further total reflection of light totally reflected by the plurality of first inclined surfaces. A plurality of second inclined surfaces; and an emission surface that emits light totally reflected by the plurality of second inclined surfaces, wherein each of the plurality of incident / exit surfaces is provided on the first inclined surface. And a plane portion that is formed by providing a partial plane on a part of each of the plurality of first inclined surfaces and functions as a transmission surface. And

According to this configuration, the light guide prism can input light from a plurality of distant positions from any one of the plurality of incident / exit surfaces and guide the light to one output surface through different reflection paths. In addition, the light guide prism can transmit light incident from the plane portion without being totally reflected. For this reason, if the light guide prism of this configuration is used, the light from the plurality of light sources is transmitted to the detected object, and the light from the plurality of positions of the detected object is used using different reflection paths. It becomes possible to lead to a single light receiving element. That is, according to this structure, the light guide prism used for the optical sensor which can detect the information of the detected object moving relatively with respect to the sensor main body at a low cost from a plurality of positions separated from each other can be provided.

According to the present invention, it is possible to provide an optical sensor capable of detecting information at a low cost from a plurality of positions that are not in the vicinity of an object to be detected that moves relative to the sensor body. Moreover, according to this invention, the light guide prism used for such an optical sensor can be provided.

It is a schematic perspective view which shows the external appearance of the optical sensor of 1st Embodiment of this invention. It is a schematic sectional drawing which shows the structure of the sensor part with which the optical sensor of 1st Embodiment is provided. It is a schematic perspective view at the time of seeing the light guide prism of 1st Embodiment from diagonally upward. It is a schematic perspective view at the time of seeing the light guide prism of 1st Embodiment from diagonally downward. It is a figure for demonstrating the effect | action of the plane part which the light guide prism of 1st Embodiment has. It is a figure for demonstrating the effect | action of the 1st-3rd inclined surface which the light guide prism of 1st Embodiment has. It is a block diagram which shows the circuit structure in the optical sensor of 1st Embodiment. It is a flowchart which shows the flow of the initial adjustment in the optical sensor of 1st Embodiment. It is a flowchart which shows the operation | movement at the time of operation | use of the optical sensor of 1st Embodiment. It is a schematic plan view which shows the state in which the optical sensor of 1st Embodiment was attached to the conveying apparatus for gift certificate conveyance. It is a schematic diagram for demonstrating the structural example of a gift certificate. It is a figure which shows the state in which the direction of the gift certificate conveyed by a conveying apparatus is upside down compared with the case of FIG. It is a schematic sectional drawing which shows the structure of the sensor part with which the optical sensor of 2nd Embodiment of this invention is provided. It is a schematic diagram for demonstrating the structural example of the gift certificate different from the gift certificate of FIG. It is a schematic sectional drawing which shows the structure of the sensor part with which the optical sensor of 3rd Embodiment of this invention is provided. It is a block diagram which shows the circuit structure in the optical sensor of 3rd Embodiment. It is a figure which shows the modification of this invention, and is a figure which shows the structural example of the light guide prism in case the number of light sources is three. It is a figure which shows the modification of this invention, and is a figure which shows the structure by which a light source and a light receiving element are arrange | positioned on a mutually opposing surface side seeing from a to-be-detected object. It is the schematic which shows the structure of the optical system of the conventional optical sensor.

Explanation of symbols

1, 2, 3 Optical sensor 21 First light source 22 Second light source 25 Light guide prism (light guide)
27 Light-receiving photodiode (light-receiving element)
41, 51

Light guide portion

41a, 51a

First half mirror

41b, 51b

Second half mirror

41c, 51c

First reflection mirror

41d, 51d Second reflection mirror 70 Detected object 81 Planar portion (transmission surface)
82 First inclined surface (total reflection surface)
83 Second inclined surface (total reflection surface)
251 Input / output surface (a)
252 Input / output surface (b)
253 Output surface 254 First inclined surface (a) (total reflection surface)
255 1st inclined surface (b) (total reflection surface)
256 Second inclined surface (total reflection surface)
257 groove 258 flat surface (transmission surface)

Hereinafter, embodiments of the optical sensor of the present invention will be described with reference to the drawings. The optical sensor of the present invention is an optical sensor that irradiates light to a detected object that moves relative to the sensor body and detects light from the detected object. Here, examples of the detected object include paper sheets such as gift certificates, stock certificates, bonds, and bills, and cards such as prepaid cards and credit cards.

(First embodiment)
First, the optical sensor of the first embodiment will be described. The optical sensor of the first embodiment is configured as an optical sensor capable of detecting special ink that emits fluorescence having a wavelength in the infrared region when irradiated with light in the visible region.

FIG. 1 is a schematic perspective view showing the appearance of the optical sensor of the first embodiment. As shown in FIG. 1, the optical sensor 1 of the present embodiment includes a housing 11 and a sensor cover 12. A sensor unit (to be described later) is accommodated in the housing 11. The first window portion 12a and the second window portion 12b of the sensor cover 12 formed of a transparent resin emit light from the sensor portion to the outside, and incident light from the outside to the sensor portion. It is provided to make it.

FIG. 2 is a schematic cross-sectional view showing a configuration of a sensor unit included in the optical sensor 1 of the first embodiment. In FIG. 2, the object to be detected is also shown for convenience of explanation. As shown in FIG. 2, the sensor unit 20 includes a first light source 21, a second light source 22, a first light projecting filter 23, a second light projecting filter 24, and a light guide prism (light guide unit). 25, a light receiving side filter 26, a light receiving photodiode 27, a first light quantity monitor 28, a second light quantity monitor 29, and a circuit board 30.

In the optical sensor 1 of the first embodiment, each of the first light source 21 and the second light source 22 is configured by an LED (Light emitting diode) that emits light with a wavelength of 590 nm (amber light). ing. The reason why the two light sources of the first light source 21 and the second light source 22 are provided is that the two information are not in the vicinity of the object to be detected 70 (the two positions are separated by, for example, several centimeters). It is for detecting. In addition, although LED is used as a light source in this embodiment, it is not limited to this, For example, other light emitting elements, such as a semiconductor laser, may be used.

The first light projecting side filter 23 and the second light projecting side filter 24 are both high-pass filters that transmit visible light and cut infrared light with respect to light emitted from the first light source 21 or the second light source 22. (Infrared cut filter). In this embodiment, for example, the transmittance of light with a wavelength of 400 to 580 nm is 60% or more, the transmittance of light with a wavelength of 580 to 600 nm is 40% or more, and the transmittance of light with a wavelength of 750 to 800 nm is 0.6%. Hereinafter, a filter having a light transmittance of 0.2% or less for light having a wavelength of 800 to 1000 nm is used.

The light guide prism 25 transmits most of the light emitted from the first light source 21 and the second light source 22 through the flat portion 258 and guides it to the detected object 70. On the other hand, most of the light from the detected object 70 entering through the first window portion 12a of the sensor cover 12 is guided to the light receiving photodiode 27 while being totally reflected. Further, most of the light from the detected object 70 incident through the second window portion 12b of the sensor cover 12 is entirely reflected by a reflection path different from the light incident through the first window portion 12a. The light is guided to the light receiving photodiode 27 while being reflected.

The light guide prism 25 of the present embodiment is formed by resin-molding, for example, Acrypet (registered trademark; a methacrylic resin molding material of Mitsubishi Rayon, a colorless transparent resin), and is composed of a single member. FIG. 3A is a schematic perspective view of the light guide prism 25 according to the first embodiment as viewed obliquely from above. FIG. 3B is a schematic perspective view of the light guide prism 25 according to the first embodiment viewed obliquely from below.

As shown in FIGS. 3A and 3B, the light guide prism 25 includes an incident / exit surface (a) 251 and an incident / exit surface (b) 252 formed in a substantially circular shape, and an output surface 253 formed in a substantially rectangular shape. And comprising. The incident / exit surface (a) 251 is a light exit surface for guiding light from the first light source 21 to the detected object 70 and an incident surface on which light from the detected object 70 is incident. The incident / exit surface (b) 252 is a light exit surface for guiding the light from the second light source 22 to the detected object 70 and an incident surface on which the light from the detected object 70 is incident. The emission surface 253 is an emission surface of light when the light from the detected object 70 is guided to the light receiving photodiode 27. The light guide prism 25 has a bilaterally symmetric structure with respect to a plane that includes the central portion of the emission surface 253 and is orthogonal to the emission surface 253.

The inclined surface facing the input / output surface (a) 251 or the input / output surface (b) 252 is the same as the first inclined surface (a) 254 (inclination angle: about 36 °, see FIG. 5) having different inclination angles. 1 inclined surface (b) 255 (inclination angle: about 45 °, see FIG. 5). The first inclined surface (a) 254 and the first inclined surface (b) 255 are opposed to the second inclined surface 256 (inclination angle: about 32 °, see FIG. 5). The first inclined surface (a) 254 and the first inclined surface (b) 255 have a groove 257 formed in a part thereof, and the bottom surface of the groove 257 includes an incident / exit surface (a) 251 and an incident / exit surface ( b) and a plane portion 258 parallel to the emission surface 253.

The operation of the light guide prism 25 formed in this way will be described with reference to FIGS. FIG. 4 is a diagram for explaining the operation of the flat portion 258 included in the light guide prism 25 of the first embodiment. FIG. 5 is a diagram for explaining the operation of the first

inclined surfaces

254 and 255 and the second inclined surface 256 included in the light guide prism 25 of the first embodiment.

As shown in FIG. 4, the light emitted from the first light source 21 or the second light source 22 and incident on the flat surface portion 258 passes through the flat surface portion 258 and reaches the detected object 70. That is, the flat portion 258 functions as a transmission surface. However, since the light emitted from the first light source 21 and the second light source 22 has some extent, there is also light that hits the first inclined surface 254 or the second inclined surface 255 instead of the flat portion 258. Such light is reflected and lost, but this amount is relatively small and does not cause a problem. Note that the plane portion 258 also transmits light from the detected object 70.

5 is a diagram for explaining the operation of the first inclined surface (a) 254 and the second inclined surface 256, and the right diagram in FIG. 5 is the first inclined surface (b) 255 and It is a figure for demonstrating the effect | action of the 2nd inclined surface. As shown in FIG. 5, the light incident on the light guide prism 25 from the detected object 70 is totally reflected by the first inclined surface (a) 254 or the first inclined surface (b) 255. Thereafter, the light is further totally reflected by the second inclined surface 256 and guided to the light receiving photodiode 27. That is, the first inclined surface (a) 254, the first inclined surface (b) 255, and the second inclined surface 256 function as a total reflection surface.

As described above, in the present embodiment, the light incident on the light guide prism 25 from the detected object 70 is finally totally reflected by the second inclined surface 256 and guided to the light receiving photodiode 27. It has become. In order to reduce light loss at this time, the first inclined surface (a) 254 and the first inclined surface (b) 255 having different inclination angles are provided. The inclination angle of the first inclined surface (a) 254 is appropriately designed according to the length of the light guide prism 25 in the left-right direction (the left-right direction is the direction when referring to FIG. 2). is there.

Since the light from the detected object 70 is scattered light, most of the light from the detected object 70 is the first inclined surface (a) 254 or the first inclined surface (b) 255. , Either incident. However, some of the light is incident on the plane portion 258. Since such light is transmitted through the flat portion 258, light loss occurs. However, the ratio of the light incident on the flat portion 258 is small and does not cause a problem.

Returning to FIG. 2, the light-receiving side filter 26 cuts visible light and transmits only infrared light with respect to the light guided to the light-receiving photodiode 27 by the light guide prism 25 (infrared transmission). Filter). In the present embodiment, for example, a filter having a light transmittance of 80% or more at a wavelength of 950 nm and a light transmittance of 1% or less at a wavelength of 800 nm is used.

The light receiving photodiode 27 receives the light that has passed through the light receiving side filter 26, photoelectrically converts it, and outputs an electrical signal. As the light receiving photodiode 27, for example, a silicon_pin photodiode having a sensitivity wavelength range of 320 to 1100 nm and a peak sensitivity wavelength of 960 nm is used.

The first light quantity monitor 28 is used to receive a part of the light emitted from the first light source 21 and detect the light quantity level of the light emitted from the first light source 21. The second light quantity monitor 29 is used to receive a part of the light emitted from the second light source 22 and detect the light quantity level of the light emitted from the second light source 22. The LEDs used for the first light source 21 and the second light source 22 may vary in the amount of light even when driven with the same setting conditions due to temperature changes and deterioration. For this reason, in the optical sensor 1 of the present embodiment, the first light amount monitor 28 and the second light amount monitor 29 are provided so that the amount of light emitted from the first light source 21 and the second light source 22 can be constant. Provided.

As the first light quantity monitor 28 and the second light quantity monitor 29, for example, a photo IC diode having a sensitivity wavelength range of 300 to 1000 nm is used. In the optical sensor 1 of the present embodiment, the light receiving portion of the first light quantity monitor 28 or the second light quantity monitor 29 is disposed at substantially the same height as the light emitting surface of the first light source 21 or the second light source 22. It has a configuration. In this case, due to the directivity of the LEDs used as the

light sources

21 and 22, the light amount monitors 28 and 29 are provided in a place where the light emission amount is small. However, since the light quantity monitors 28 and 29 are provided at positions very close to the first light source 21 or the second light source 22, respectively, sufficient output as a light quantity monitor can be obtained. Of course, the positions of the light quantity monitors 28 and 29 may be arranged at positions where the amount of emitted light is larger.

The circuit board 30 is provided to control the driving of the first light source 21 and the second light source 22 and to process electrical signals from the light receiving photodiode 27, the first light amount monitor 28, and the second light amount monitor 29. FIG. 6 is a block diagram illustrating a circuit configuration of the optical sensor 1 according to the first embodiment.

The light source driving unit 31 is electrically connected to the first light source 21 and the second light source 22 and adjusts the output level of light emitted from them. The adjustment of the output levels of the

light sources

21 and 22 during operation is performed by monitoring monitor signals obtained from the first light quantity monitor 28 and the second light quantity monitor 29, as will be described later, and assuming that the monitor output is constant at a predetermined value. It is adjusted to become.

The identification signal processing unit 32 is electrically connected to the light receiving photodiode 27. Then, the gain adjustment of the electric signal output from the light receiving photodiode 27 is performed by the variable gain unit 32a. The filter / amplifier unit 32b removes noise contained in the signal whose gain has been adjusted and amplifies the signal. The identification signal processing unit 32 inputs the identification signal obtained by processing to the CPU 35. Details of the CPU 35 will be described later.

The first monitor signal processing unit 33 is electrically connected to the first light quantity monitor 28. Then, the gain adjustment of the electric signal output from the first light quantity monitor 28 is performed by the variable gain unit 33a. The filter / amplifier unit 33b removes noise and amplifies the signal included in the signal whose gain has been adjusted. The first monitor signal processing unit 33 inputs a monitor signal obtained by processing to the CPU 35.

The second monitor signal processing unit 34 is electrically connected to the second light quantity monitor 29. Then, the gain adjustment of the electric signal output from the second light quantity monitor 29 is performed by the variable gain unit 34a. The filter / amplifier unit 34b removes noise contained in the signal whose gain has been adjusted and amplifies the signal. The second monitor signal processing unit 34 inputs the monitor signal obtained by processing to the CPU 35.

The CPU 35 includes a built-in AD converter, and converts the received identification signal and monitor signal into digital signals. Then, the CPU 35 processes the identification signal based on the received identification signal and data stored in advance in a memory (not shown) to detect characteristics such as color tone and shading on the object 70 to be detected. Classification of the detected object 70, authenticity determination, and the like are performed. In addition, the CPU 35 confirms the outputs from the first light amount monitor 28 and the second light amount monitor 29 based on the received monitor signal, and outputs a signal to the light source driving unit 31 based on the confirmation result, so that the first light source 21 and the second light source 22 Adjust the drive current.

Next, the initial adjustment of the optical sensor 1 of the first embodiment will be described with reference to FIG. FIG. 7 is a flowchart showing a flow of initial adjustment in the optical sensor 1 of the first embodiment. First, when the optical sensor 1 is assembled, gain adjustment on the light receiving photodiode 27 side is performed using the reference light (step S1). The reference light is prepared in advance as a jig, and the adjustment value adjusted here is used as a fixed value thereafter. Gain adjustment is performed by adjusting the variable gain section 32a.

When the gain of the light-receiving photodiode 27 is determined, the first light source 21 and the second light source 22 are set so that the output level from the light-receiving photodiode 27 becomes a target value using the reference detection object. The LED light amount (LED light emission amount) is adjusted separately (step S2). The reference object to be detected is coated with the same special ink that is to be detected using the optical sensor 1 during operation. The LED light amount is adjusted by adjusting the light source driving unit 31.

When the LED light amount is determined for each of the

light sources

21 and 22, the output level of the first light amount monitor 28 and the output level of the second light amount monitor 29 are set to target values under the determined LED light amount. Gain adjustment is performed (step S3). The adjustment value adjusted here is used as a fixed value thereafter.

The operation of the optical sensor 1 that has been initially adjusted as described above will be described with reference to FIG. FIG. 8 is a flowchart showing an operation during operation of the optical sensor 1 of the first embodiment.

During operation, first, the first light source 21 and the second light source 22 of the optical sensor 1 are turned on (step S11). Then, it is confirmed whether or not the monitor outputs from the first light quantity monitor 28 and the second light quantity monitor 29 are within a target range (step S12). This confirmation is performed by the CPU 35. Specifically, the confirmation is performed by comparing the target value stored in advance in the memory with the output value obtained from the monitor signal.

In the case where the monitor output is not within the target range for at least one of the first light source 21 and the second light source 22, the output of the light source (LED) whose monitor output is not within the target range is output. A change is made (step S13). For example, the output change amount may be determined with reference to an amount by which the monitor output deviates from the target range. When the output of the first light source 21 and / or the second light source 22 is changed, it is confirmed again whether or not the monitor output is within the target range, and this operation is performed until the monitor output is within the target range. Is repeated.

When the monitor output is within the target range for both the first light source 21 and the second light source 22, the measurement of the detected object 70 is performed with both the light sources turned on. That is, the output from the light receiving photodiode 27 is taken into the CPU 35 (step S14). The CPU 35 performs classification of the detected object 70, authenticity determination, and the like based on the acquired information and information stored in advance in the memory.

Thereafter, it is confirmed whether or not the measurement by the optical sensor 1 is finished (step S15). When the measurement is continued (the measurement is not terminated), the operations from step S12 to step S14 are repeated.

Next, the operation of the optical sensor 1 according to the first embodiment configured as described above will be described using an example in which the detected object 70 is a gift certificate. FIG. 9 is a schematic plan view showing a state in which the optical sensor 1 of the first embodiment is attached to a gift certificate carrying device. As shown in FIG. 9, the transport device is provided with an upper guide plate 61 and a lower guide plate 62, and a portion sandwiched between the upper guide plate 61 and the lower guide plate 62 serves as a transport path 63. In addition, the conveyance direction of the gift certificate 70 in FIG. 9 is a direction perpendicular | vertical with respect to a paper surface.

The optical sensor 1 is disposed on the upper side of the upper guide plate 61, and is attached so that the sensor cover 12 side faces downward (the sensor cover 12 faces the transport path). And only the truncated cone 12c part (there are two) of the front-end | tip of the sensor cover 12 is attached so that it may protrude from the upper guide plate 61 and may protrude on the conveyance path 63. FIG. The reason for projecting only the portion of the truncated cone 12 c is to prevent the conveyed gift certificate 70 from hitting the sensor cover 12 of the optical sensor 1 and causing a jam.

Further, the optical sensor 1 is attached to the transport device so that the window portion 12a and the window portion 12b of the sensor cover 12 are aligned in a direction substantially perpendicular to the transport direction of the gift certificate 70. For this reason, it is possible to obtain information of two regions separated in the direction non-parallel to the conveyance direction of the gift certificate 70 by the optical sensor 1.

FIG. 10 is a schematic diagram for explaining a configuration example of a gift certificate. As shown in FIG. 10, the gift certificate 70 has a bar code 71 printed with special ink in a portion surrounded by a broken line. In this example, the barcode 71 is printed with special ink that emits fluorescence having a wavelength in the infrared region when irradiated with visible light (in this embodiment, amber light with a wavelength of 590 nm). For this reason, the barcode 71 cannot be visually observed. The use of the bar code 71 that cannot be seen in this way has an advantage that the appearance of the gift certificate is not impaired and an advantage that information for preventing forgery is provided.

By the way, the gift certificate 70 transported by the transport device may be transported along the transport path 63 in the direction as shown in FIG. 10, or may be transported along the transport path 63 in the direction as shown in FIG. For this reason, unless information is obtained from two areas separated in a direction non-parallel to the direction of conveyance of the gift certificate 70, the barcode information of the gift certificate 70 conveyed through the conveyance device is missed. There is a case. In addition, FIG. 11 is a figure which shows the state which the direction of the gift certificate conveyed by a conveying apparatus is upside down compared with the case of FIG.

In this regard, according to the optical sensor 1 of the first embodiment, light is separately irradiated to two regions that are separated from each other. Then, fluorescence (infrared light) generated in each of the two regions can be detected by the single light receiving photodiode 27 by the light guide prism 25. For this reason, the barcode 71 can be detected regardless of the orientation of the gift certificate 70 in the vertical direction.

As described above, according to the optical sensor 1 of the first embodiment, information on two areas away from the object to be detected 70 (the two areas are separated in a direction non-parallel to the transport direction) 22 and a single light receiving photodiode 27. That is, unlike the conventional configuration, it is not necessary to increase the number of light receiving elements in accordance with the increase in the number of light sources, and the use of the optical sensor 1 of this embodiment is advantageous in terms of cost (the signal received by the light receiving element). Including the advantage that only one processing circuit is required. The light guide prism 25 can be manufactured by resin molding, and the introduction of the light guide prism 25 can be reduced in cost compared to the increase in the number of light receiving elements.

Further, in the case of the optical sensor 1 according to the first embodiment, if the distance between the two

light sources

21 and 21 and the size design of the light guide prism 25 are changed, the separation distance between the two points where the detection target 70 is to be detected can be set. You can change it freely. For this reason, the application example of the optical sensor 1 of the first embodiment may be as follows, for example.

That is, for example, the optical sensor 1 according to the first embodiment is applied so that the presence of the special ink included in the detected object 70 is not lost due to a shift in the transfer position of the detected object 70 conveyed through the conveying device. Also good.

Further, for example, when there are a plurality of types of the detected object 70 conveyed by the conveying device, the width of the detected object 70 may differ depending on the type. In such a case, the optical sensor 1 of the present embodiment may be applied to detect the presence of the special ink for any type of the detected object 70 so as not to be damaged.

Furthermore, for example, when special ink is printed in two areas, the optical sensor 1 of the first embodiment may be applied to detect the special ink at these two positions. In the case of this application example, light from a plurality of positions can be combined and received by the light receiving element, and the presence of special ink can be easily confirmed.

(Second Embodiment)
Next, an optical sensor according to a second embodiment will be described. FIG. 12 is a schematic cross-sectional view illustrating a configuration of a sensor unit included in the optical sensor according to the second embodiment. In FIG. 12, the object to be detected is also shown for convenience of explanation.

The optical sensor 2 according to the second embodiment is different from the optical sensor according to the first embodiment in that the light guide unit 41 included in the sensor unit 40 includes a plurality of mirrors instead of the prism as in the first embodiment. Different from 1. Therefore, only the configuration of the light guide unit 41 is basically described, and the other parts are denoted by the same reference numerals as those in the first embodiment, and the description thereof is omitted unless particularly necessary. The appearance configuration of the optical sensor 2 of the second embodiment is the same as that of the first embodiment.

The light guide unit 41 includes a first half mirror 41a, a second half mirror 41b, a first reflection mirror 41c, and a second reflection mirror 41d. The first half mirror 41a and the second half mirror 41b, and the first reflection mirror 41c and the second reflection mirror 41d are arranged at symmetrical positions, respectively.

The first half mirror 41a and the second half mirror 41b are both configured to transmit a part of incident light and reflect the remaining part. Such a half mirror may be a metal half mirror formed by, for example, forming a metal reflective film very thinly on a transparent member. As another form, a dielectric half mirror (dichroic mirror) formed by laminating a plurality of substances extremely thinly on a transparent member may be used.

In the latter case, it is possible to form a dielectric multilayer film that transmits visible light but does not transmit (reflect) infrared light. In the case of such a configuration, the

light projecting filters

23 and 24 and the light receiving filter 26 can be omitted.

The first reflection mirror 41c and the second reflection mirror 41d are formed so as to reflect all incident light. Such a reflection mirror can be produced by providing a metal film on a transparent member.

FIG. 12 shows a configuration in which the mirrors 41a to 41d are arranged as separate members. However, a resin molded body having a plurality of (four in this embodiment) inclined surfaces serving as reflecting surfaces is formed, and the first half mirror 41a, the second half mirror 41b, the first reflecting mirror 41c, and the first reflecting mirrors are formed on the inclined surfaces. It is good also as a structure which forms the 2 reflection mirror 41d (refer the structure of 3rd Embodiment mentioned later). In this configuration, since the light guide portion 41 can be a single member, the number of parts can be reduced, and it can be manufactured at low cost. Therefore, it can be said that it is a more preferable aspect.

The operation of the optical sensor 2 including the light guide unit 41 configured as described above will be described. Here, a case where the half mirror is a metal half mirror will be described. The light emitted from the first light source 21 is cut from infrared light by the first light-projecting filter 23, partially transmitted by the first half mirror 41a, and partially reflected. The light transmitted through the first half mirror 41 a reaches the detection object 70 via the first window portion 12 a of the sensor cover 12.

The light from the detected object 70 generated by the light irradiation from the first light source 21 reaches the first half mirror 41a via the first window portion 12a. Here, the first half mirror 41a transmits part of the light and reflects part of the light. The light reflected by the first half mirror 41a is all reflected by the first reflection mirror 41c, and only the infrared light of the reflected light reflected here passes through the light receiving side filter 27 and receives the light receiving photodiode 27. It leads to.

Similarly, by emitting light from the second light source 22, the light generated from the detected object 70 reaches the light receiving photodiode 27 via the second half mirror 41b and the second reflecting mirror 41d. That is, similarly to the optical sensor 1 of the first embodiment, the optical sensor 2 of the second embodiment irradiates two separate areas that are not in the vicinity of the detected object 70 separately, and thereby separate positions. In this configuration, the light generated in (1) is guided to a single light-receiving photodiode 27 using different reflection paths depending on the light guide unit 41.

Therefore, the optical sensor 2 of the second embodiment can obtain the same effects as those of the first embodiment. And the optical sensor 2 of 2nd Embodiment can be used by the method similar to the optical sensor 1 of 1st Embodiment.

(Third embodiment)
Next, an optical sensor according to a third embodiment will be described. In the first and second embodiments described above, the case where the wavelengths of the light emitted from the first light source 21 and the second light source 22 are the same has been described. The optical sensor of the third embodiment is a configuration example when the wavelengths of light emitted by the first light source 21 and the second light source 22 are different.

Here, the reason why the first light source 21 and the second light source 22 need to have different wavelengths of emitted light will be described. FIG. 13 is a schematic diagram for explaining a configuration example of a gift certificate different from the gift certificate of FIG. 10.

As shown in FIG. 13, information is printed with special inks having different properties in two areas (first area 72 and second area 73) separated in a direction non-parallel to the conveyance direction of the gift certificate 70. There may be cases. Specifically, for example, a configuration using the special ink as described in the first embodiment for the first region 72 and using the special ink that generates fluorescence (visible light) when the second region 73 is irradiated with ultraviolet rays. There can be. For such a gift certificate 70, when trying to detect the information of the

areas

72 and 73, light sources having different wavelengths are required. The optical sensor of the third embodiment has a configuration that assumes such a gift certificate 70.

FIG. 14 is a schematic cross-sectional view illustrating a configuration of a sensor unit included in the optical sensor of the third embodiment. In FIG. 14, for the convenience of explanation, an object to be detected (gift certificate) is also shown. The external configuration of the optical sensor 3 of the third embodiment is the same as that of the first embodiment.

As shown in FIG. 14, the sensor unit 50 of the optical sensor 3 of the third embodiment includes a first light source 21, a second light source 22, a first light projecting filter 23, and a second light projecting filter 24. A light guide 51, a light receiving photodiode 27, a first light quantity monitor 28, a second light quantity monitor 29, and a circuit board 30.

The configurations of the first light source 21, the first light projecting side filter 23, the light receiving photodiode 27, the first light amount monitor 28, and the second light amount monitor 29 are the same as the configurations of the first embodiment. Then, explanation is omitted.

The second light source 22 is an LED that emits ultraviolet light having a wavelength of 370 nm. The second light projecting side filter 24 is a blue filter that passes ultraviolet light and cuts visible light. Specifically, the blue filter is, for example, a filter having a maximum transmittance with respect to light having a wavelength of 370 nm.

The light guide portion 51 has a structure in which a plurality of mirrors 51a to 51d are formed on a transparent resin member 51e that is integrally formed. Specifically, a first half mirror 51a, a second half mirror 51b, a first reflection mirror 51c, and a second reflection mirror 51d are formed on four inclined surfaces of the transparent resin member 51e.

The first half mirror 51a and the second half mirror 51b are metal half mirrors in this embodiment, and have a configuration in which a thin metal film is formed on the inclined surface of the transparent resin member 51e. However, these may be a dielectric half mirror formed by forming a dielectric multilayer film on the inclined surface of the transparent resin member 51e. The first reflection mirror 51c and the second reflection mirror 51d are metal mirrors formed by forming a metal film on the inclined surface of the transparent resin member 51e so as to reflect all incident light.

In the light guide 51, a first light receiving side filter 52 is disposed between the first half mirror 51a and the first reflecting mirror 51c. The first light-receiving side filter 52 is an infrared transmission filter that cuts visible light and transmits only infrared light. In the present embodiment, as the first light receiving side filter 52, for example, a filter having a light transmittance of 80% or more for a wavelength of 950 nm and a light transmittance of 1% or less for a light having a wavelength of 800 nm is used.

In the light guide 51, a second light receiving side filter 53 is disposed between the second half mirror 51b and the second reflecting mirror 51d. The second light receiving side filter 53 is a visible transmission filter that cuts ultraviolet light and transmits visible light. In the present embodiment, as the second light-receiving side filter 53, for example, a filter that transmits light of a red component (wavelength of about 640 nm to about 770 nm) is used. However, different filters may be used according to the color of light (fluorescence) to be detected (for example, orange, yellow, etc.).

The operation of the light guide 51 configured as described above will be described. First, the light emitted from the first light source 21 will be described. A part of the light incident on the light guide 51 is reflected by the first half mirror 51 a, but the remaining part is transmitted and reaches the object 70 to be detected. Then, a part of the light from the detected object 70 generated thereby is transmitted through the first half mirror 51a, but the remaining part is reflected. The light reflected by the first half mirror 51 a passes through the first light receiving side filter 52 (note that the visible light component is cut), and is totally reflected by the first reflecting mirror 51 c to the light receiving photodiode 27. It reaches.

Next, the light emitted from the second light source 22 will be described. A part of the light incident on the light guide 51 is reflected by the second half mirror 51 b, but the remaining part is transmitted and reaches the object 70 to be detected. A part of the light generated from the detected object 70 is transmitted through the second half mirror 51b, but the remaining part is reflected. The light reflected by the second half mirror 51b passes through the second light-receiving side filter 53 (note that the ultraviolet light component is cut), and is totally reflected by the first reflecting mirror 51c to the light-receiving photodiode 27. It reaches.

Similar to the optical sensor 1 of the first embodiment, the circuit board 30 controls the driving of the first light source 21 and the second light source 22, and includes the light receiving photodiode 27, the first light amount monitor 28, and the second light amount monitor 29. It is provided to perform the electrical signal processing. FIG. 15 is a block diagram illustrating a circuit configuration of the optical sensor 3 according to the third embodiment.

As shown in FIG. 15, the circuit configuration of the optical sensor 3 of the third embodiment is basically the same as that of the optical sensor 1 of the first embodiment. The same parts as those in the first embodiment are denoted by the same reference numerals, and the description thereof is omitted. The difference from the first embodiment is that an alternating lighting control unit 36 is provided.

The alternating lighting control unit 36 controls the operation of the light source driving unit 31 so that the first light source 21 and the second light source 22 are switched in order at predetermined time intervals and turned on (alternate lighting). In the optical sensor 3 of the third embodiment, as described above, the object is to detect two pieces of information having different properties printed at different positions of the detected object 70.

For this reason, the optical sensor 3 has two

light sources

21 and 22 that irradiate different positions and emit light having different wavelengths. The optical sensor 3 according to the third embodiment is also configured to detect information of two different areas with only the single light receiving photodiode 27. Therefore, unless the first light source 21 and the second light source 22 are turned on separately, the two special inks having different properties printed on the detection target 70 cannot be detected. For this reason, it is necessary to alternately turn on the first light source 21 and the second light source 22, and an alternating lighting control unit 36 is provided.

Note that the time interval at which the alternating lighting control unit 36 alternately turns on the first light source 21 and the second light source 22 is measured in consideration of, for example, the speed at which the detected object 70 is conveyed, the size at which the special ink is printed, and the like. Or by performing a simulation or the like.

In the present embodiment, the wavelength of the fluorescence received by the light receiving photodiode 27 differs depending on whether the first light source 21 is turned on or the second light source 22 is turned on. In this case, the sensitivity of the light receiving photodiode may be different. In consideration of such points, the gain adjustment value of the light receiving photodiode 27 is separately determined when the first light source 21 is used and when the second light source 22 is used at the initial adjustment stage of the optical sensor 3. The setting condition of the identification signal processing unit 32 may be changed in accordance with alternating lighting of the

light sources

21 and 22.

If the optical sensor 3 of the third embodiment configured as described above is attached to the transport device, special inks having different properties in the two areas of the transported gift certificate 70 are separately detected, and the gift certificate classification and It is possible to perform authenticity determination. In the case of the configuration of the present embodiment, it is necessary to manage the gift certificate 70 so that the top and bottom of the gift certificate 70 are not reversed (see FIGS. 10 and 11) during transportation.

In the case of the configuration of the present embodiment, the two regions of the detected object 70 are separately irradiated with light, thereby causing the light generated at different positions to be single by using different reflection paths by the light guide unit 51. The light receiving photodiode 27 is guided. That is, the number of light receiving elements can be reduced to one without increasing the number of light receiving elements in accordance with the increase in the number of light sources. Therefore, even when two special inks having different properties are printed at a plurality of positions that are not in the vicinity of the detected object 70, it is possible to detect such information at a low cost.

(Other)
The present invention is not limited to the embodiment described above, and various modifications can be made without departing from the object of the present invention.

For example, in the first to third embodiments described above, with reference to the drawings shown in FIGS. 2, 12, and 14, the

light guide portions

25, 41, and 51 have a symmetrical structure. did. However, the present invention is not limited to this configuration. It suffices if information of two areas separated in a direction non-parallel to the conveyance direction of the detected object 70 can be detected, and the light guides 25, 41, 51 may of course have an asymmetric structure.

Further, for example, in the first and second embodiments described above, the first light source 21 and the second light source 22 are not alternately lit. However, the present invention is not limited to this, and the first light source 21 and the second light source 22 may be alternately turned on. In this way, it is possible to distinguish whether the information detected by the light receiving photodiode 27 is based on when the first light source 21 is turned on or when the second light source 22 is turned on. That is, it can be grasped where information (for example, bar code information) printed with special ink is located in the gift certificate 70 to be conveyed.

In addition, when such alternating lighting is performed, the S / N ratio of the signal when the special ink (bar code 71) of the gift certificate 70 is detected can be improved. That is, when alternating lighting is not performed, there is a possibility that unnecessary light enters the light receiving photodiode 27 by turning on one of the light sources, and the S / N may be deteriorated. This point can be eliminated by alternating lighting.

Further, for example, in the first to third embodiments described above, information on two distant areas that are not in the vicinity of the detected object 70 is obtained by using two

light sources

21 and 22 and one light receiving photodiode 27 ( The configuration of detecting using a light receiving element) is shown. However, the present invention is not limited to this, and the optical sensor of the present invention is a sensor that detects information of three or more regions that are not in the vicinity of the detected object 70 by using one light receiving element with three or more light sources. Can be applied. Hereinafter, the configuration of the light guide unit in the case of detecting information on three separate areas that are not in the vicinity of the detected object 70 is shown in FIG.

FIG. 16 is a diagram illustrating a configuration example of the light guide prism when the number of light sources is three. FIG. 16 is a plan view showing a modified configuration of the light guide prism shown in FIG. 3A. The configuration illustrated in FIG. 16 is a configuration that can detect information of a portion surrounded by a broken-line circle. In the figure, 81 is a plane part (transmission surface) for transmitting light emitted from the light source, and 82 is a first inclined surface (total reflection surface) for totally reflecting light from the object to be detected. Reference numeral 83 denotes a second inclined surface (total reflection surface) that further totally reflects the light reflected by the first inclined surface 82. In the description method of FIG. 16, the first inclined surface 82 indicates the outer surface of the light guide prism, and the second inclined surface 83 indicates the inner surface of the light guide prism. The light guide prism configured in this way also transmits light emitted from a plurality of light sources and guides it to a detected object, and uses different reflection paths for light from a plurality of positions of the detected object. To a single light receiving element.

In the first to third embodiments described above, the

light sources

21 and 22 and the light receiving photodiode 27 are arranged on the same side when viewed from the object 70 to be detected. However, the present invention is not limited to this configuration. That is, for example, as shown in FIG. 17, the

light sources

21 and 22 are arranged on one side with the detected object 70 conveyed on the conveyance path 63 interposed therebetween, and the light guide unit (for example, the light guide prism 25) is arranged on the other side. However, it may be arranged upside down as in the case of FIG. However, the arrangement as in the first to third embodiments is preferable because the optical sensor can be reduced in size and can be applied to an object to be detected that does not transmit light.

In the first to third embodiments described above, the configuration in which the detected object is transported by the transport device is shown as the configuration in which the detected object moves relative to the optical sensor. However, the optical sensor of the present invention can be applied even when the object to be detected moves relative to the optical sensor by moving the optical sensor itself.

The present invention uses, for example, an optical method to classify paper sheets such as gift certificates, stock certificates, receivables, and banknotes, and prepaid cards, cards such as credit cards, and the like. It can be suitably used as a sensor for performing authenticity determination or the like.

Claims

An optical sensor that irradiates a detected object that moves relative to the sensor body and detects light from the detected object,
A plurality of light sources for separately irradiating a plurality of separated positions of the object to be detected;
A single light receiving element that receives and photoelectrically converts light from the plurality of positions of the detected object;
The light emitted from each of the plurality of light sources is transmitted and guided to the detected object, and the light from the plurality of positions is guided to the single light receiving element using different reflection paths. A light guide;
An optical sensor comprising:
The optical sensor according to claim 1, wherein the light guide unit is made of a single member.
The single member is provided for each of the plurality of light sources to transmit light emitted from the plurality of light sources, and to totally reflect light from the object to be detected. The optical sensor according to claim 2, wherein the optical sensor is a light guide prism including a plurality of total reflection surfaces.
The light guide unit includes a plurality of mirrors, and the plurality of mirrors transmits a part of incident light and reflects a remaining part of the plurality of first mirrors and reflects all incident light. The optical sensor according to claim 1, further comprising a plurality of second mirrors.
The optical sensor according to claim 1, wherein the optical sensor is formed so that a wavelength of light emitted from the light source is different from a wavelength of light received by the single light receiving element.
6. The optical sensor according to claim 5, wherein the light emitted from the light source is visible light, and the light received by the single light receiving element is infrared light.
The optical sensor according to claim 1, wherein each of the plurality of light sources emits light having a different wavelength.
The optical sensor according to claim 1, wherein the plurality of light sources are alternately lit.
The optical sensor according to claim 1, wherein the plurality of light sources and the single light receiving element are arranged on the same side as viewed from the object to be detected.
The plurality of light sources include two light sources, a first light source and a second light source,
The light guide prism is formed of resin,
Light that can pass between the first light source and the light guide prism, between the second light source and the light guide prism, and between the light guide prism and the single light receiving element. The optical sensor according to claim 3, wherein a filter that restricts the light to light in a specific wavelength region is disposed.
A plurality of light incident / exit surfaces that function as light exit surfaces and light incident surfaces and are located on the same plane;
A plurality of first inclined surfaces which are opposed to each other in a state of being inclined with respect to each of the plurality of incident / exit surfaces and function as total reflection surfaces;
A plurality of second inclined surfaces provided to further totally reflect the light totally reflected by the plurality of first inclined surfaces;
An emission surface that emits light totally reflected by the plurality of second inclined surfaces, and
The first inclined surface is arranged to face each of the plurality of incident / exit surfaces in parallel, and a partial flat surface is provided on a part of each of the plurality of first inclined surfaces. A light guide prism, characterized by being provided with a flat portion that is formed by and functions as a transmission surface.