JP3651616B2 - Mark detection method and apparatus - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for optically detecting various marks such as barcodes and characters provided on various items such as various prepaid cards such as a pass ticket and a telephone card, and a detection device that implements the detection method. In particular, the present invention relates to a detection mark formed with a fluorescent material.
[0002]
[Prior art]
Conventionally, as a mark detection method of this type, a mark is formed using a fluorescent substance that emits light in the infrared wavelength region, while utilizing the fact that the emission center wavelength of the light irradiated to this mark and the generated fluorescence are different, There is known a method for determining the presence or absence of a mark by separating only a fluorescent component from incident light using an optical filter (see, for example, Japanese Patent Publication Nos. 54-22326 and 61-18231).
[0003]
On the other hand, the present applicant previously irradiated light on a mark formed of a fluorescent material intermittently, and simply detected the presence or absence of afterglow generated from the mark during the stop period of irradiation light. A method and apparatus for detecting the formation position has been proposed (see, for example, Japanese Patent Application Laid-Open No. 5-20512).
[0004]
[Problems to be solved by the invention]
However, in the method of separating reflected light and fluorescence using the optical filter described above, the emission center wavelength of both lights approaches and the intensity of fluorescence is extremely weak compared to the intensity of reflected light. It is technically difficult to accurately separate light, and there is a problem that a large amount of components of reflected light remain to cause a decrease in detection accuracy.
[0005]
On the other hand, in the method using only afterglow, the intensity of reflected light can be effectively separated and detected without causing a problem, but dust adheres to the light incident surface of the detector. If the detection sensitivity is reduced, the absolute value of the afterglow generated from the mark is also lowered, and the afterglow detection accuracy may be lowered.
[0006]
Furthermore, in the method using only afterglow, when external light having the same wavelength as or near to the fluorescence wavelength is simultaneously irradiated, the light is directly input to the light receiving element and converted into an electric signal. As a result, there is a possibility that it may be mistaken for fluorescence even though fluorescence is not generated. Therefore, in order to prevent such misidentification, there is a disadvantage that the use environment is limited, for example, it is required to use the light irradiation and detection position while shielding the external light.
[0007]
As a result of studying such inconveniences, the present inventors have found that the relationship between the light irradiated to the fluorescent material and the generated fluorescence is substantially the same as the relationship between the applied voltage in the CR circuit and the terminal voltage of the capacitor. While changing while maintaining an equivalent phase relationship, external light is generally a constant intensity or random intensity change, and by utilizing the difference in waveform between such signals, It was found that even when various types of light coexist, only the fluorescent component can be accurately extracted.
[0008]
In other words, when periodically and intermittently irradiating light on a mark formed of a fluorescent material, the light emitted from the mark portion is reflected by the mark and the medium below it and the same timing as the reflected light. Thus, fluorescence whose intensity increases or decreases and disturbance light at a substantially constant level are superimposed. Therefore, reflected light, disturbance light, and fluorescence can be separated using the difference in waveform between the two.
[0009]
The present invention has been made on the basis of the above-mentioned knowledge, and does not simply detect the intensity of incident light intensity or the intensity of afterglow, but comprehensively determines changes in the waveform of incident light to form a mark. It is an object of the present invention to provide a detection method and apparatus capable of accurately detecting a mark formation position by determining the position in spite of deterioration of detection conditions of fluorescence generated from the mark.
[0010]
[Means for Solving the Problems]
As shown in FIG. 1, the mark detection method according to the present invention irradiates a mark 17 formed with a fluorescent material on an arbitrary medium 9 with light 17 and detects the fluorescence 30 generated from the mark 16. The position where the mark 16 is formed is detected.
[0011]
A light irradiation step of intermittently irradiating light 17 having a substantially constant intensity, a photoelectric conversion step of taking light emitted from the light irradiation position as incident light 18 and converting it into an electric signal, and converted electric The detection value 19 is compared between the fluorescence intensity detection step of extracting an electric signal having a magnitude corresponding to the change of the fluorescence component in the incident light 18 from the signal as the detection value 19 and the detection value 19 and the comparison value 20 described above. A mark determination step of determining that the mark is formed when the value exceeds 20.
[0012]
Furthermore, it is preferable to provide an incident intensity detecting step of taking out an electric signal having a magnitude corresponding to the change of the incident light 18 during the light irradiation period as the comparison value 20.
[0013]
Further, in the above-described fluorescence intensity detection step, a detection value is formed by detecting the intensity of the incident light 18 immediately after the irradiation light 17 is stopped, and in the above-described incident intensity detection step, immediately before the irradiation light 17 starts irradiation. It is possible to individually detect the intensity of the incident light 18 and the intensity of the incident light 18 immediately before the irradiation light 17 is stopped, and to form a comparison value by dividing the difference between the two.
[0014]
Furthermore, in the above-described fluorescence intensity detection step, the intensity of the incident light 18 immediately after the start of the irradiation of the irradiation light 17 and the intensity of the incident light 18 immediately before the irradiation of the irradiation light 17 are stopped are individually detected. The detected value 19 may be created by taking
[0015]
In the above-described fluorescence intensity detection step, the electrical signal corresponding to the incident light 18 is synchronously detected with a signal that is 90 degrees out of phase with the irradiation light 17, thereby detecting a phase shift from the component of the irradiation light 17. You can also create a value. In this case, in the above-described incident intensity detection step, the electrical signal corresponding to the incident light 18 is synchronously detected with a signal having the same phase as that of the irradiation light 17, so that the reflected light 67 in the incident light 18 has substantially the same phase component. Corresponding comparison values are created.
[0016]
The mark detection apparatus according to the present invention emits light 17 to a mark 16 formed with a fluorescent material on an arbitrary medium 9 as shown in FIG. A light irradiating means 10 for irradiating light 17 having a substantially constant intensity intermittently with a predetermined period; and The photoelectric conversion means 12 that takes in the light emitted from the irradiation position as incident light 18 and converts it into an electrical signal, and the signal intensity immediately after the irradiation stop is detected in synchronization with the irradiation timing of the irradiation light 17 in the light irradiation means 10 described above. Fluorescence intensity detection means 13 that can be output as value 19, and the lowest value corresponding to immediately before the start of irradiation, in synchronization with the irradiation timing of irradiation light 17 in light irradiation means 10 described above, The incident intensity detection means 8 that can output the maximum value corresponding to immediately before the shooting is stopped and the comparison value 20 obtained by dividing the difference between the two and the comparison value 20 and the detection value 19 are compared. Mark determining means 14 for determining the formation position of the mark 16 when the value 20 is exceeded is provided.
[0017]
In addition, while synchronizing the fluorescence intensity detection means 13 with the timing of 90 ° phase shift from the irradiation period of the irradiation light 17 by the light irradiation means 10, half of the output signal from the photoelectric conversion means 12 is inverted and amplified. The detection value 19 can be formed by selectively extracting a DC component from the output signal.
[0018]
Further, both the fluorescence intensity detection means 13 and the incident intensity detection means 8 described above are provided with an analog switch at least at one input end of the differential amplifier circuit, and the analog switch is provided in the fluorescence intensity detection means 13. The incident light intensity detection means 8 is turned on corresponding to a period of the same phase as the light irradiation period, and then the output signal is turned to a low frequency range. You may make it filter with a passage-type filtering means.
[0019]
Furthermore, on the input side of the photoelectric conversion means 12, the optical filtering means 11 that selectively takes in the light component having the same wavelength as the fluorescence 30 from the incident light 18, while the comparison value output from the incident intensity detection means 8 is provided. Is further provided with a signal input determination unit 15 for determining whether or not the mark value is a significant value, and the mark determination unit 14 performs the determination operation only in a period when the signal input determination unit 15 determines that the comparison value is a significant value. It is preferable to be configured to do so.
[0020]
[Action]
With the configuration described above, when the light 17 is irradiated from the light irradiation means 10 to the mark 16, fluorescence 30 having a predetermined wavelength is generated from the light irradiation position on the mark 16 in addition to the reflected light 67. The incident light 18 including the reflected light 67 and the fluorescent light 30 or other external light 70 is selectively taken in by the optical filtering means 11 only with light having the same wavelength as that of the fluorescent light 30, and then the photoelectric conversion means 12. After being converted into an electrical signal, predetermined signal processing is performed.
[0021]
The fluorescence intensity detection means 13 takes out the detection value 19 corresponding to the fluorescence component from the incident light 18 in synchronization with the irradiation timing of the irradiation light 17. On the other hand, the incident intensity detecting means 8 also detects the presence or absence of a mark by forming a comparison value 20 having a magnitude corresponding to the change of the incident light 18 and comparing them with the mark determining means 14.
[0022]
At the same time, the signal input determination means 15 always determines the magnitude of the incident light 18 and starts the determination operation in the mark determination means 14 only when a significant incident light 18 is detected, so that only genuine data can be obtained. The detection value 19 and the comparison value 20 are used.
[0023]
【The invention's effect】
As described above, the present invention comprehensively determines the signal change of the incident light 18 in synchronization with the irradiation light 17 to form the detection value 19 corresponding to the component of the fluorescence 30, while the magnitude of the incident light 18 itself. Since the comparison value 20 is created based on the above, the fluorescence component is reduced due to the deterioration of the optical sensor or the adhesion of dust, or the irradiation light 17 is specularly reflected and resembles the fluorescence component in a pseudo manner. Even when a waveform change occurs, the mark formation position can be accurately detected.
[0024]
Further, by shifting the phase 90 degrees from the irradiation light 17 and synchronously detecting the incident light to extract the fluorescent component, the influence of disturbance light can be reduced as much as possible, and the presence or absence of a minute phosphor can be determined.
[0025]
Further, by making the determination operation of the presence / absence of the mark 16 only when the intensity of the incident light 18 exceeds a certain level, erroneous determination due to noise can be prevented as much as possible.
[0026]
【Example】
Hereinafter, the present invention will be described in more detail based on an example implemented in a mark detection device that reads a bar code-shaped mark formed on a cash card-shaped card as illustrated in FIGS. Of course, the present invention can be implemented in substantially the same manner in an apparatus for detecting mark information of various shapes including characters provided on various articles.
[0027]
As shown in FIG. 2, the card 21 uses, for example, a white polyester film as a base material 22, and on the upper surface side of the base material 22, a base layer 23 of an arbitrary design whose reflectance is adjusted in advance is printed and formed. By applying a magnetic paint on the lower surface side, a magnetic layer 24 for recording main information in a rewritable manner is formed. Furthermore, a mark 16 made of a fluorescent material is printed on the base layer 23 on the upper surface side so that security sub-information can be fixed.
[0028]
The mark 16 formed on the base layer 23 is invisible, for example, made of a fluorescent material that generates fluorescence 30 having a wavelength different from the central wavelength of the irradiation light 17 corresponding to the irradiation light 17 in the infrared region. A bar-shaped mark 16 in the form of a strip perpendicular to the longitudinal direction of the card 21 is formed, and predetermined security sub-information such as a card issuing store code or a personal identification number is used for the card with the mark 16. 21 is recorded on the recording medium.
[0029]
The bar code formed as the mark 16 includes a ground pattern part 25 in the conventional bar code shown in FIG. 3A and a data part 27 constituted by a plurality of bars 26 indicated by hatching. b) Inverted as indicated by the hatched lines in FIG. 5B, and by providing a phosphor layer in the gap 29 provided between the bars 26 and the introduction part 28 sandwiching the front and back of the data part 27, the data part 27 is Before the detection by scanning, the introduction part 28 sufficiently longer than each bar 26 and the gap 29 constituting the data part 27 is detected.
[0030]
By adopting such a configuration, it is possible to make the contrast uniform over the entire area of the data portion 27, to prevent erroneous detection of the thickness of the first bar 26a at the scanning start position, and to automatically adjust the detection level. It is configured to be more stable.
[0031]
Examples of the fluorescent material constituting the mark 16 include rare earth elements such as neodymium (Nd), ytterbium (Yb), eurobium (Eu), thulium (Tm), praseodymium (Pr), dysprosium (Dy), or the like. It is preferable that the mixture is formed of a phosphor powder in which the emission center is used and the emission center includes an oxide such as phosphate, molybdate or tungstate. However, as long as the fluorescence 30 having afterglow is generated by irradiating with light having an arbitrary wavelength, it is needless to say that the material can be changed as appropriate.
[0032]
In this embodiment, when a fluorescent paint containing a phosphor such as Li (NdO.9YbO.1) P4O12 is formed by screen printing, for example, when excitation light in the near infrared region having a wavelength of about 800 nm is irradiated. In addition, the fluorescence 30 in the infrared region having a peak value at a wavelength near 1000 nm is generated, and the afterglow with a decay time of 90 to 10% of about 400 to 600 μs is generated even when the light irradiation is stopped. doing.
[0033]
As shown in FIG. 4, the mark detection apparatus according to the present invention includes a signal generation unit 31 that generates various control signals, a running unit 32 of the card 21 formed as described above, and its A light irradiation unit 33 for the card 21 transferred by the card running unit 32, a photoelectric conversion unit 34 that takes in the light 18 from the position irradiated with the light 17 and converts it into an electrical signal, and a mark 16 from the converted electrical signal Are provided with a mark detection unit 35 that outputs a mark signal S1 corresponding to the formation position, and a data processing unit 36 that determines the data content on the card 21 from the detected mark signal S1.
[0034]
The signal generation unit 31 generates at least a drive signal S2 used in the light irradiation unit 33 and three types of timing signals S3, S4, and S5 used in the mark detection unit 35. The signal generation unit 31 generates a clock signal S6. 37 and a control signal generation circuit 38 for generating various control signals S2 to S5 from the generated clock signal S6.
[0035]
As shown in FIG. 5A, the clock signal generation circuit 37 continuously generates a pulsed clock signal S6 at a constant time interval of about 100 μsec, for example. On the other hand, in the control signal generation circuit 38, the signal level is switched every time five clock signals S6 are input, so that the level changes at a time interval of about 500 μsec as shown in FIG. 5B. A wavy drive signal S2 is formed. Further, the control signal generation circuit 38 outputs a pulse signal in conjunction with the input of, for example, the fourth, sixth and ninth clock signals S6 from the rising edge of the drive signal S2, thereby allowing the control signal generation circuit 38 to output the pulse signal shown in FIG. The three types of timing signals S3 to S5 synchronized with the drive signal S2 are formed as in (e).
[0036]
The card running unit 32 horizontally shifts at a constant speed of, for example, about 200 to 400 mm per second while supporting both side edges of the card 21 by the rollers 40 that are rotationally driven by the motor drive circuit 39 corresponding to the insertion time of the card 21. Thus, the bar code-like mark 16 formed with a fluorescent material on the upper surface side of the card 21 passes through the lower positions of the light irradiation unit 33 and the photoelectric conversion unit 34. Data relating to the operation timing of the motor drive circuit 39 is sent to the data processing unit 36 to inform the data processing necessary time for determining the mark contents.
[0037]
The light irradiation unit 33 includes a light emission source drive circuit 41 that amplifies the power of the drive signal S2 output from the signal generation unit 31, and a light emission source 42 that generates light by energization from the light source drive circuit 41. Is done.
[0038]
As shown in FIG. 2, the light emission source 42 is obtained by attaching a glass fiber light guide 44 to a light emitting portion of a light emitting element 43 such as a light emitting diode that generates near infrared light having a light emission center wavelength of about 800 nm. . The front end of the light guide 44 is brought close to the surface of the card 21 to a distance of 2 mm or less, and the entire light guide 44 is placed on the surface orthogonal to the transition direction of the mark 16 and 45 from the horizontal direction. It is arranged with an inclination angle of ˜60 °.
[0039]
The photoelectric conversion unit 34 that converts the light 18 incident from the light irradiation position on the card 21 into an electrical signal, a detector 45 that converts the incident light 18 into a change in current, and the current change into a voltage change. It is comprised from the alternating current amplifier circuit 46 amplified to predetermined magnitude | size.
[0040]
The detector 45 selectively passes only light of the wavelength of the fluorescence 30 generated from the mark 16 on the light receiving surface of a light receiving element 47 such as a photocell or a photodiode having a light receiving sensitivity in the infrared region. A light guide 49, which is substantially the same as the light source 42 side, is used.
[0041]
Here, the front end of the light guide 49 on the detector 45 side is adjacent to the front end of the light guide 44 on the light emission source 42 side, and on the surface orthogonal to the transition direction of the mark 16 described above, for example, about 105 to 115 °. By providing the inclination angle, only the light 18 emitted from the irradiation position of the irradiation light 17 on the surface of the mark 16 is captured. The captured light 18 is converted into a voltage proportional to the intensity of the incident light 18 by the light receiving element 47, amplified to a predetermined voltage value by the AC amplifier circuit 46, and then input to the mark detection unit 35 to be marked. A signal S1 corresponding to the position is extracted.
[0042]
The present invention is characterized by the configuration of the mark detection unit 35, and includes a sample hold circuit 50 for measuring a change in the waveform shape of the incident light 18 illustrated in FIG. Comparison circuits 51, 52, and 53, and first and second display circuits 54 and 55.
[0043]
As illustrated in FIG. 6, the sample hold circuit 50 includes a capacitor 57 for holding an input voltage value on the input side of a voltage buffer circuit 56 using an OP amplifier, and timing signals S <b> 3 to S <b> 3 sent from the signal generator 31. 5 includes an analog switch 58 that is turned on at the input of S5 as one set of sampling circuits 60, and includes a first to a third set of sampling circuits 60, and is sent from the photoelectric conversion unit 34. A series of voltage changes S7 corresponding to the intensity of the incident light 18 as exemplified in f) are individually and periodically sampled at a plurality of time points, and each detected value can be held until the next sampling time. Is.
[0044]
In this embodiment, the timing signal S3 shown in FIG. 5C is applied to the first sampling circuit 60a, and the voltage value immediately before stopping the irradiation of the light 17 is indicated by a thick line in FIG. The maximum value Vm of the incident light 18 is detected. Further, the timing signal S4 shown in FIG. 5D is applied to the second sampling circuit 60b, and the intensity of the afterglow shown by the broken line in FIG. Detect as. Further, the timing signal S5 shown in FIG. 5E is applied to the third sampling circuit 60c, and the lowest value of the incident light 18 shown by the thin line in FIG. Detect values individually. In this way, the change in the waveform of the incident light 18 is obtained as the change in the voltage value so that the proportion of the afterglow intensity in the whole can be determined.
[0045]
An OP amplifier is used for the first comparison circuit 51 for determining the value of each detection value described above, and the afterglow voltage value Vd extracted from the second sampling circuit 60b of the sample hold circuit 50 is applied to the negative input terminal thereof. The detection value is input as it is. On the other hand, by dividing the difference between the voltage values extracted from the first and third sampling circuits 60a and 60c by the variable resistor 62, the voltage value Vc is input as a comparison value indicated by a one-dot chain line in FIG. When the detection value Vd exceeds the comparison value Vc, a predetermined signal S8 is output to the third comparison circuit 53.
[0046]
Here, the second comparison circuit 52 compares the maximum value Vm output from the first sampling circuit 60a with a predetermined set value, and outputs a predetermined signal S9 during a period when the maximum value Vm is below the set value. When the maximum value Vm exceeds the set value, the output of the signal S9 is stopped, and its output terminal is connected in parallel to the output side of the first comparison circuit 51 via the diode 63 connected in the forward direction. A signal is input to the three comparison circuit 53.
[0047]
The third comparison circuit 53 applies the output from the first comparison circuit 51 and the second comparison circuit 52 to the negative side input terminal of the OP amplifier and compares it with the set value, and provides a switching element 64 by an FET provided on the output side. On-off regulation. While both the output voltages from the first and second comparison circuits 51 and 52 are lower than the set value, the “1” signal corresponding to the detection of the mark 16 is output to the data processing unit 36, but at least one of them is output. When there is an "H" level signal output from the comparison circuits 51 and 52, the signal S1 sent to the data processing unit 36 becomes "0" indicating that the mark 16 is not detected.
[0048]
Accordingly, during the period in which the output signal S8 from the first comparison circuit 51 is indefinite because the intensity of the incident light 18 is low, an “H” level signal S9 is output from the second comparison circuit 52 to the minus of the third comparison circuit 53. As a result of being applied to the side input terminal, the output of the third comparison circuit 53 is forcibly set to the “0” state to inform the data processor 36 that the mark 16 has not been detected.
[0049]
On the other hand, in the state where the intensity of the incident light 18 is equal to or higher than a certain value and the mark detection is normally performed, the output from the second comparison circuit 52 is lowered to the “L” level. The third comparison circuit 53 operates in response to the change in the output level from the output, that is, the detection of the fluorescence component, and the presence / absence of mark detection is determined as shown in FIG.
[0050]
The determination possible time by the third comparison circuit 53 is displayed by causing the LED 65 of the first display circuit 54 provided on the output side of the second comparison circuit 52 to emit light. Further, the detection time of the mark 16 is notified by causing the LED 66 of the second display circuit 55 provided on the output side of the third comparison circuit 53 to emit light.
[0051]
Note that the capacitor 57 and the resistor 59 provided on the input side of the sample hold circuit 50 and the capacitor 68 and the resistor 69 provided on the input side of the third comparison circuit 53 constitute an integrating circuit. This prevents the input level from rising instantaneously and malfunctioning.
[0052]
Also, the timing of sending the timing signals S3 to S5 is set closer to the flickering timing of the irradiation light 17 in correspondence with the emission characteristics of the fluorescence 30 generated from the mark 16, so that the fluorescence component and the reflected light component can be transmitted. Separation can be performed more accurately. In that case, it is possible to detect the value of the fluorescence 30 from the voltage values immediately after the start of light irradiation and immediately before the irradiation stop without detecting afterglow.
[0053]
Further, the comparison operation of each detection value may be a digital type using a microprocessor instead of the analog type using an OP amplifier as described above. In this case, instead of or in addition to selectively sampling the voltage value in the characteristic portion of the input waveform, the entire shape of the waveform can be detected and the change can be obtained by digital processing.
[0054]
[Second embodiment]
Next, another embodiment of the present invention will be described with reference to FIGS. 7 to 9. Since the configuration other than the mark detection unit 35 ′ and the signal generation unit 31 ′ is substantially the same as that of the first embodiment described above, Description is omitted.
[0055]
Here, as shown in FIG. 9A, the clock signal generation circuit 37 ′ in the signal generation unit 31 ′ continuously generates a pulsed clock signal S6 at a constant time interval of about 250 μs, for example. On the other hand, the control signal generation circuit 38 'includes two D-type flip-flops 71 and 72 as shown in FIG. 8, and both clock signal input terminals 73 and 74 are connected to each other by the clock signal generation circuit 37'. Connect in parallel with the output. Further, between the data input terminal 75 of the first flip-flop 71 and the inverting output terminal 76 of the second flip-flop 72, the non-inverting output terminal 77 of the first flip-flop 71 and the data input terminal 78 of the second flip-flop 72 are connected. They are directly connected to each other.
[0056]
With this configuration, every time two clock signals S6 are input from the non-inverting output terminal 77 of the first flip-flop 71, the output level is inverted at a time interval of about 500 μs as shown in FIG. 9B. A rectangular wave drive signal S2 is output. Further, from the non-inverted output terminal 79 in the second flip-flop 72, the first control signal S10 having the same frequency as the drive signal S2 and delayed in phase by 90 degrees as shown in FIG. As shown in FIG. 9D, the second control signals S11 having the same frequency as the drive signal S2 and the phase advanced by 90 degrees are output.
[0057]
The light emission source drive circuit 41 is a transistor switch 80 that is turned on in conjunction with the input of the drive signal S2, and connects the Zener diode 81 between the emitter and base to limit the base voltage, while the light emitting element is connected in series with the collector. 43 are connected.
[0058]
As shown in FIGS. 7 and 8, the mark detection unit 35 ′ uses the first and second control signals S10 and S11 to shape the detection signal S7 into a predetermined signal S12 illustrated in FIG. 9F. When the synchronous rectification circuit 82, the low-pass filtering circuit 83 that removes the AC component from the signal S12 and outputs the signal S13 that increases or decreases in response to the detection of the fluorescence 30, and the input of the significant signal S13 are determined. And a comparison circuit 84 for outputting the mark signal S1.
[0059]
The synchronous rectifier circuit 82 described above connects the two input terminals 87 and 88 in the differential amplifier circuit 86 using the OP amplifier 85 in parallel to input the detection signal S7, and in series with each of the input terminals 87 and 88. The analog switches 89 and 90 are interposed, and the analog switches 89 and 90 are individually controlled to be turned on and off using the control signals S10 and S11.
[0060]
That is, the analog switch 89 provided at the positive input terminal 87 of the OP amplifier 85 is turned on corresponding to the “H” level period in the first control signal S10, while the analog switch 90 provided at the negative input terminal 88 is turned on. The second control signal S11 is turned on corresponding to the “H” level period.
[0061]
Here, the “H” level period in the first control signal S10 is a period delayed by 90 degrees from the irradiation period of the light 17 by the light emitting element 43, whereas the “H” level period in the second control signal S11. The period is a period in which the phase is advanced by 90 degrees. Therefore, in the detection signal S7 input to the synchronous rectification circuit 82, the second half of the light irradiation and the first half of the period when the light irradiation is stopped are stopped at the positive input terminal 87 via the analog switch 89. The latter half period and the first half period irradiated with light are separately input to the minus side input terminal 88. As a result, from the output side of the synchronous rectifier circuit 82, as shown in FIG. 9 (f), the input period of the detection signal S7 with respect to the plus side input end 87 is non-inverted and amplified as a change in plus voltage. During the input period to 88, the signal S12 is extracted as a negative voltage change by inverting amplification.
[0062]
By the way, the change of the detection signal S7 is composed of only the mark 16 and the reflected light 67 from the display medium 9 of the mark 16 in a period in which the light 17 is not irradiated on the mark 16, and as a result, FIG. ) Becomes a rectangular wave as shown by the one-dot chain line. Therefore, the output signal from the synchronous rectifier circuit 82 is also inverted in the first half of the reflected light component and non-inverted in the second half as shown by the hatching in FIG. Are extracted as equal signals.
[0063]
On the other hand, when the irradiation light 17 scans the mark 16, due to the afterglow of the fluorescence 30, as shown by the solid line in FIG. It shows a change in which the fluorescent component decreases exponentially from when the light irradiation is stopped. Therefore, the output signal S12 from the synchronous rectification circuit 82 is also extracted as a signal that is sufficiently larger on the plus side than on the minus side as a result of being selectively non-inverted and amplified in the period when the fluorescent component is large and inverted in the small period. It is.
[0064]
Therefore, in this embodiment, the output signal S12 from the synchronous rectifier circuit 82 is further removed through the low-pass filter circuit 83 to remove only the DC component. That is, in the state where the mark 16 indicated by the alternate long and short dash line in FIG. 9E and FIG. 9F is not scanned, the plus side and the minus side are equal, so both are canceled and the filtering circuit There is no output from 83.
[0065]
However, in the state where the mark 16 indicated by the solid line in FIG. 9E is scanned, the components of the external light 70 and the reflected light 67 are canceled, but the component of the fluorescence 30 is on the positive side. Overwhelmingly large. Therefore, the signal S13 is extracted from the filtering circuit 83 as a positive DC voltage.
[0066]
This signal S13 is further input to a comparison circuit 84 using an OP amplifier 91, and a comparison voltage obtained by dividing a voltage stabilized by a constant voltage diode 92 by a variable resistor 93. Vc ' And its size are compared, and the comparison voltage Vc ' When a significant signal S13 exceeding 1 is input, the output voltage is set to the “H” level state, and the mark signal S1 for specifying the detection of the mark position is output.
[0067]
[Third embodiment]
Further, the mark detector 35 ″ shown in FIG. 10 is based on the configuration of the mark detector 35 ′ in the second embodiment described above, and the second and third comparison circuits 52 and 53 in the mark detector 35 in the first embodiment. In addition, peripheral circuits of the first and second display circuits 54 and 55 are added, so that only the parts different from the above embodiment will be described below.
[0068]
In other words, the synchronous rectification circuit 82 ′ that extracts the fluorescent component includes the analog switch 89 only at the plus side input end 87 of the OP amplifier 85. Furthermore, the comparison value in the comparison circuit 84, which was a semi-fixed value in the second embodiment, is changed in accordance with the magnitude of the input signal. Here, the circuit configuration is substantially the same as that of the synchronous rectification circuit 82 ′ for obtaining the fluorescent component described above, but the drive signal S2 corresponding to the irradiation timing of the irradiation light 17 is used as a signal for turning on / off the analog switch 89a. doing.
[0069]
With this configuration, the signal S14 output from the synchronous rectifier circuit 82a is inverted only in the afterglow part in the fluorescence component as shown in FIG. 9 (g), and therefore after passing through the low-pass filter circuit 83a, Since the fluorescent portion is canceled and a signal S15 whose level changes with the magnitude corresponding to the reflected light 67 is output, the comparison value is obtained by dividing the signal with the variable resistor 93. Vc ″ Is created.
[0070]
The period of the drive signal S2 in the above embodiment is about 1 msec, which is set to about twice the afterglow time of the fluorescent material constituting the mark 16, but the value of both the period and the afterglow time can be changed as appropriate. Can be implemented.
[0071]
Furthermore, instead of fixing the mark detection device side and moving the mark 16, for example, the light irradiation unit 33 and the photoelectric conversion unit 34 are integrated into a portable probe shape, and the mark 16 side is fixed and detected. The apparatus side may be shifted manually or automatically. Alternatively, the irradiation light 17 may be scanned, and the light 18 emitted from the scanning position may be detected by the detector 45.
[Brief description of the drawings]
FIG. 1 is a schematic diagram showing a basic configuration of the present invention.
FIG. 2 is an explanatory diagram showing light irradiation and a detection state with respect to a mark.
FIG. 3 is an explanatory diagram showing an example of a barcode-shaped mark formed on a card.
FIG. 4 is a block diagram showing the overall configuration of the mark detection apparatus according to the first embodiment of the present invention.
FIG. 5 is a waveform diagram showing a mark detection state in the first embodiment.
FIG. 6 is an electric circuit diagram showing details of a mark detection unit in the first embodiment.
FIG. 7 is a block diagram illustrating an overall configuration of a mark detection apparatus according to a second embodiment of the present invention.
FIG. 8 is an electric circuit diagram showing details of a mark detection unit in the second embodiment.
FIG. 9 is a waveform diagram showing the relationship between signals in the second embodiment.
FIG. 10 is an electric circuit diagram showing details of a mark detection unit in a third example similar to the second example.
[Explanation of symbols]
8 Incident intensity detection means
9 Display media
10 Light irradiation means
11 Optical filtering means
12 Photoelectric conversion means
13 Waveform detection means
14 Mark judgment means
15 Signal input judging means
16 mark
17 Irradiation light
18 Incident light
19 Detection value
20 Comparison value
21 cards
30 fluorescence
31 Signal generator
32 Card running section
33 Light irradiation part
34 Photoelectric converter
35 Mark detector
36 Data processing section
37 Clock signal generation circuit
38 Control signal generation circuit
39 Motor drive circuit
41 Light source driving circuit
42 Light source
43 Light Emitting Element
45 Detector
46 AC amplifier circuit
47 Light receiving element
48 Optical filters
50 Sample hold circuit
51 First comparison circuit
52 Second comparison circuit
53 Third comparison circuit
54 First display circuit
55 Second display circuit
56 Voltage buffer circuit
60 Sampling circuit
67 Reflected light
70 External light
71 First flip-flop
72 Second flip-flop
82 Synchronous rectifier circuit
83 Filter circuit
84 Comparison circuit
89 Analog switch
90 Analog switch

Claims (3)

A method of detecting the formation position of a mark by irradiating light on a mark formed with a fluorescent material on an arbitrary medium and detecting the fluorescence generated from the mark by the irradiated light,
A light irradiation step of intermittently irradiating the mark with irradiation light having a substantially constant intensity;
In the light irradiation step, reflected light emitted correspondingly during irradiation of the irradiation light from the light irradiation position on the mark, and its intensity increases with a predetermined time constant from the start of irradiation of the irradiation light. A photoelectric conversion process that takes in incident light including fluorescence whose intensity decreases and converts it into an electrical signal;
A fluorescence intensity detection step for extracting, as a detection value, an electrical signal having a magnitude corresponding to a change in the intensity of the fluorescence in the incident light from the electrical signal converted in the photoelectric conversion step;
An incident intensity detection step for extracting, as a comparison value, an electric signal having a magnitude corresponding to the intensity change of the incident light during the irradiation period of the irradiation light from the electric signal converted in the photoelectric conversion step,
A mark determination step of comparing the detection value with the comparison value and determining that the detection value is a boundary position of the mark when the detection value exceeds the comparison value ;
Further, in the fluorescence intensity detection step, a detection value is formed from an electrical signal having a magnitude corresponding to the intensity of incident light immediately after the irradiation light irradiation is stopped.
In the incident intensity detection step, the intensity of incident light immediately before the start of irradiation of the irradiation light and an electric signal having a magnitude corresponding to the intensity of incident light immediately before stop of irradiation of the irradiation light are individually detected, and the difference between the two is detected. A mark detection method in which a comparison value is formed by dividing the pressure . A mark detection device that irradiates a mark formed with a fluorescent material on an arbitrary medium with light, detects fluorescence generated from the mark by the irradiation light, and detects a mark formation position,
A light irradiating means for irradiating the mark while intermittently irradiating the irradiation light with a substantially constant intensity;
From the light irradiation position on the mark by the light irradiation means, the intensity of the reflected light emitted correspondingly during the irradiation of the irradiation light and the intensity increases with a predetermined time constant from the start of irradiation of the irradiation light. Photoelectric conversion means that takes in incident light including fluorescence that decreases in intensity and converts it into an electrical signal;
Fluorescence intensity detecting means that can synchronize with the irradiation timing of the irradiation light in the light irradiation means, and that can output the signal intensity immediately after the stop of light irradiation in the electric signal output from the photoelectric conversion means, as a detection value;
Synchronize with the irradiation timing of the irradiation light in the light irradiation means, the difference between the lowest value corresponding to immediately before the irradiation light irradiation start in the electrical signal output from the photoelectric conversion means and the maximum value corresponding to immediately before the irradiation stop Incident intensity detection means capable of outputting a divided comparison value;
A mark detection apparatus comprising: a mark determination unit that compares the comparison value with a detection value and determines a mark boundary position when the detection value exceeds the comparison value . The mark detection device according to claim 2,
On the input side of the photoelectric conversion means, provided with an optical filtering means for selectively capturing a light component having the same wavelength as fluorescence from the incident light,
Signal input determination means for determining whether or not the comparison value output from the incident intensity detection means is a significant value;
A mark detection apparatus in which the mark determination unit can perform a determination operation only during a period in which the signal input determination unit determines that the comparison value is a significant value .

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