JP2007178284A - Detection device for detecting an object embedded in a planar object - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a detection device capable of detecting surely information of the position or the like of an object buried in a planar object by detecting an electromagnetic wave transmitted through the planar object or an electromagnetic wave reflected by the planar object by scanning surely the whole surface of the planar object by the electromagnetic wave. <P>SOLUTION: This detection device for detecting the buried object in the planar object includes a conveyance mechanism 13 for conveying the planar object, an irradiation part 10 for irradiating the conveyed planar object linearly with the electromagnetic wave, and a detection part 11 for detecting the transmitted electromagnetic wave through the planar object or the reflected electromagnetic wave from the planar object in the electromagnetic wave. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

The present invention detects an object embedded in a planar object, such as a detection device that detects the position of an object such as an RFID tag (non-contact IC tag) in a planar object from a change in the propagation state of a propagating electromagnetic wave. The present invention relates to a detecting device. In particular, an electromagnetic wave including a frequency range of 30 GHz to 30 THz (an electromagnetic wave of a frequency range called a millimeter wave to a terahertz wave, also referred to as a terahertz wave in this specification) is embedded in a planar object such as paper. The present invention relates to an apparatus for detecting the position of an object such as an RFID tag.

In recent years, an ID element (RFID: Radio Frequency IDentification) technology has been developed for electronically holding individual information in a tag equipped with an IC chip and transmitting the information in a non-contact manner by electromagnetic induction. It is starting to be applied.

Specifically, as an application of such technology, information can be written in a non-contact manner using a predetermined wireless tag reader / writer or a read-only interrogator with respect to a small wireless tag (responder) storing predetermined information. And a system that performs reading. Since such a system communicates data using an antenna provided in each of the tag and the reader / writer, and can communicate even when the tag is separated from the reader / writer, it is used for various applications. .

RFID tags that are small enough to fit into paper have been developed, and ultra-small tags with a size of 0.4 mm square and a thickness of 0.06 mm have been developed. Patent Document 1 discloses a technology that uses this to insert RFID tags into papers such as gold vouchers, forms, securities, passports, banknotes, official documents, and contracts that require authenticity determination. .

However, paper with a sufficiently small RFID tag does not impair the appearance of the paper because the tag itself is small, but the position of the tag is not known. Even if the position of the tag is controlled in the squeezing process, the exact position of the tag that has been squeezed is likely to be unknown due to deformation of the paper itself in the drying process or the like in paper production.

Since the communication distance of a small RFID tag is only on the order of millimeters to centimeters, if the user does not know the position of the tag, the reader / writer is held over the dark clouds on the paper, which is inefficient. Therefore, it may be necessary to print a mark that allows the user to know the position of the tag. In such a case, it is necessary to accurately know the position of the tag in the printing process.

In addition, when printing a mark that indicates the tag position on the RFID tag interleaved paper, even if the RFID tag position in the paper is known in advance, the tag position may differ depending on the type of paper and the print batch. In such a case, it is inefficient for the print operator to enter the tag position for each print batch.

In addition, when printing on paper in which an RFID tag is inserted, the tag may be damaged by the pressure of the roller or the like, and therefore, a change process such as reducing the pressure of the roller at the tag position must be performed. For this purpose, it is necessary to know the position of the tag.
JP 2002-298118 A

As described above, when an object such as a small RFID tag is embedded in a planar object such as paper, it is important to measure the position of the embedded object. Accordingly, an object of the present invention is to detect an object such as a small RFID tag in a planar object using an electromagnetic wave such as a terahertz wave.

In view of the above problems, a detection device of the present invention for detecting an object embedded in a planar object has the following elements. That is, a transport mechanism for transporting a planar object, an irradiation unit for linearly radiating electromagnetic waves to the transported planar object, and among the electromagnetic waves, an electromagnetic wave or a planar object that has passed through the planar object A detecting unit for detecting the electromagnetic wave reflected by.

Moreover, in view of the said subject, the processing method of this invention is characterized by the following. That is, when processing such as image formation is performed on the surface of a planar object using the above detection device, the influence of the embedded object on the processing process and the object in which the processing process is embedded based on the detection information of the detection device The processing conditions are changed to reduce the influence on the machining.

According to the detection apparatus or method of the present invention, the planar object is reliably and entirely moved by the electromagnetic wave by the joint action of the movement of the planar object by the transport mechanism and the linear electromagnetic wave to the planar object by the irradiation unit. Can scan. Therefore, by detecting the electromagnetic wave transmitted through the planar object or reflected by the planar object with the detection unit, information such as the position of the object embedded in the planar object can be reliably detected.

An embodiment of an apparatus or method for detecting an object embedded in a planar object according to the present invention will be described.

One embodiment of the detection apparatus includes a transport mechanism such as a rotating roller for transporting a planar object such as paper that is a planar object, and irradiation for irradiating electromagnetic waves linearly on the transported planar object. Part. Furthermore, a detection unit for detecting an electromagnetic wave transmitted through the planar object or an electromagnetic wave reflected by the planar object is provided. Information on the electromagnetic wave detected by the detection unit is supplied to changing means for changing the formation conditions of the image formed on the surface of the planar object such as paper, resin flat plate, wood flat plate, resin sheet or the like. . The electromagnetic wave is typically an electromagnetic wave including a frequency range of 30 GHz to 30 THz.

In particular, the present embodiment provides an apparatus for accurately determining the position of the tag on the paper in which the RFID tag is inserted regardless of the type of paper. Furthermore, it is possible to provide an apparatus for accurately measuring the position of the tag on cardboard, dark paper, or stacked paper.

Hereinafter, a description will be given of a configuration including a high-frequency electromagnetic wave generation device that generates a terahertz wave belonging to the millimeter wave band from the terahertz wave band, a high-frequency electromagnetic wave detection device that detects this electromagnetic wave, and a mechanism that transports paper in which an RFID tag is inserted To do. In this configuration, the electromagnetic wave is linearly irradiated onto the paper in which the RFID tag is inserted, and the electromagnetic wave is transmitted or reflected through the paper in which the RFID tag is inserted, and then the transmitted or reflected electromagnetic wave is detected with a high frequency electromagnetic wave. Focus on the device. The spatial intensity distribution of the electromagnetic waves over the entire surface of the paper can be measured by the cooperative action of the movement of the paper by the transport mechanism and the linear electromagnetic waves collected on the paper by the electromagnetic wave generator.

Paper and RFID tags differ in refractive index, transmittance, and other optical constants for terahertz waves and millimeter waves. For this reason, a difference appears in the intensity of the high-frequency electromagnetic wave detected by the high-frequency electromagnetic wave detection device between the high-frequency electromagnetic wave that is transmitted or reflected only by paper and the high-frequency electromagnetic wave that is transmitted or reflected by the RFID tag.

If the size of the RFID tag and the wavelength of the high-frequency electromagnetic wave to be used are approximately the same, or if the tag is smaller than the wavelength, the high-frequency electromagnetic wave is scattered by the RFID tag. In this case, the position of the RFID tag in the paper can be specified by obtaining the scattering center from the intensity distribution of the high frequency electromagnetic wave detected by the high frequency electromagnetic wave detector. On the other hand, when the size of the RFID tag is larger than the wavelength of the electromagnetic wave used, an electromagnetic wave shadow is generated behind the tag. Therefore, in this case, the position of the RFID tag can be specified from the intensity distribution of the high-frequency electromagnetic wave detected by the high-frequency electromagnetic wave detector.

Electromagnetic waves belonging to the terahertz band to the millimeter wave band have a much higher transmittance with respect to paper than visible light, and therefore, a bundle of about 100 sheets of commercially available printer paper is also transmitted. In addition, cardboard used for a cosmetic box of goods, dark-colored paper, cardboard, etc. are transmitted.

In this embodiment, the position of the RFID tag inserted in the paper can be specified regardless of the type of paper or the state of the paper. Based on this information, for example, the pressure by the fixing roller is reduced in the printing process. RFID tag damage can be reduced. Thus, by performing the printing condition changing process that reduces the influence of the printing process on the embedded object, the yield of image formation on the paper surface can be improved. Also, since the position of the RFID tag inserted is specified, based on this information, the influence of the embedded object, which is the RFID tag, on the printing process can be reduced, and the mark indicating the position of the RFID tag can be printed accurately Can do. This makes it easy for the user to read / write the information of the RFID tag inserted in the paper.

By the way, as a method for obtaining the position of a sufficiently small RFID tag, a method using visible light or a method using X-rays can be considered. That is, a method of measuring the position of the tag by using visible light or X-rays and observing through paper is also conceivable. However, when visible light is used to determine the position of the RFID tag, the visible light does not pass through dark paper or cardboard, cardboard used for product cosmetic boxes, etc. The situation where the position can be measured is limited. Also, the method of using X-rays to determine the position of the RFID tag is not very desirable because the apparatus becomes large and there is a risk of exposure.

Embodiments of a position detecting apparatus or method such as an RFID tag according to the present invention will be described below with reference to the drawings.

(Example 1)
FIG. 1 is a perspective view showing Example 1 of the present invention. In this embodiment, as shown in FIG. 1, the paper (thick paper, dark paper, etc.) on the uppermost surface of the bundle of paper 12 with the RFID tag stacked on the printing paper feed tray 14 is conveyed. Paper is fed to a printing press (not shown) using a roller 13 as a mechanism (moves to the left in FIG. 1). The terahertz wave generation device 10 and the terahertz wave detection device 11 are installed so as to sandwich the paper fed to the printing machine up and down.

Here, the terahertz wave emitted from the terahertz wave generator 10 forms a linear focal point on the paper. Then, the terahertz wave transmitted through the paper is detected by the terahertz wave detection device 11. The terahertz wave detection device 11 includes, for example, a plurality of terahertz wave detectors arranged in a line.

Since the terahertz wave is focused on the linear focus and the paper is moved to the printing press, the terahertz linear focus will scan the entire range of the paper before the paper is taken into the printing press. .

In the terahertz wave generator 10, for example, a backward traveling wave tube (BWO: Backward Wave Oscillator) having a frequency of 1 THz is used, and is condensed linearly using an optical system such as a lens or a mirror. For the terahertz wave detection device 11, for example, an array of pyro elements is used. In order to increase the detection efficiency, an optical system including a lens and a mirror may be used in front of the terahertz wave detection device 11.

Because the refractive index and transmittance of the RFID tag and paper for terahertz waves are different, the presence of the RFID tag can be determined from the difference in the intensity of the terahertz wave that has passed through the paper and the terahertz wave that has passed through the RFID tag. . Therefore, when the RFID tag is at one point on the linear focus of the terahertz wave, it is possible to determine where the RFID tag exists on the linear focus.

For example, when a terahertz wave detector 11 having a plurality of terahertz wave detectors arranged at intervals of 100 μm is used, the following signal is obtained, whereby the position of the RFID tag can be obtained. 2 (a) and 2 (b) plot the positions of the terahertz wave detectors arranged at 100 μm intervals on the horizontal axis and the intensities of the terahertz waves detected by the respective detectors on the vertical axis. When there is no RFID tag at one point on the linear focal point of the terahertz wave, the difference shown in the graphs shown in Fig. 2 (a) and (b) is obtained (however, Fig. 2 is a schematic diagram) Is). If a signal like the graph 2 in FIG. 2 (b) is obtained, it is found that the RFID tag exists at the corresponding position (the position where the intensity is lowest) on the terahertz wave line focal point.

Alternatively, the position of the RFID tag may be detected by obtaining two-dimensional image data from the paper fed by the roller 13 and the output signal from the linear detector, and performing image recognition.

FIG. 2 is a plot of only the intensity of the detected terahertz wave, but it is also possible to use both intensity and phase change, or phase change. For example, a well-known method using a means for irradiating a femtosecond laser to a photoconductive antenna made of gallium arsenide or the like as a terahertz wave source will be described. In this case, a method of irradiating a photoconductive antenna similar to that on the generation side with a femtosecond laser is also used for terahertz wave detection. The femtosecond laser is divided by a half mirror or the like, and one is irradiated to the photoconductive antenna on the generation side, and the other is irradiated to the photoconductive antenna on the detection side. At this time, a delay optical system is used that synchronizes the generated terahertz wave and the femtosecond laser light applied to the detection side so as to reach the detection side photoconductive antenna at the same time. By using a delay optical system that synchronizes the time when the generated terahertz wave reaches the detector, a time waveform graph of the terahertz wave as shown in FIG. 3 can be obtained (FIG. 3 is a schematic diagram).

FIG. 3 shows time on the horizontal axis and the amplitude of the detected terahertz wave on the vertical axis. A time waveform (a) in FIG. 3 is a time waveform of a terahertz wave when only the paper is transmitted. On the other hand, the time waveform (b) in FIG. 3 is a time waveform of the terahertz wave that has passed through the RFID tag. A time waveform (a) can be obtained by scanning the delay optical system with only the paper portion, and a time waveform (b) can be obtained by scanning the delay optical system with a portion having the RFID tag.

That is, in contrast to the terahertz wave transmitted only through the paper, the terahertz wave transmitted through the RFID tag is not only attenuated in intensity but also delayed in phase. From both the intensity attenuation and phase delay of the terahertz wave, it was found that the RFID tag exists in the relevant part (which can be seen from the position of the terahertz wave detector that detected both and the position on the detected time axis). The position of the tag can be obtained.

If the position of the RFID tag can be detected, damage to the RFID tag may be prevented by reducing the pressure of the roller 13 on the RFID tag in the printing press. In addition, a mark that clearly indicates the position of the RFID tag to the user may be printed. In this case, there is provided changing means for changing the formation conditions (for example, the pressure of the fixing roller) of the mark (image) formed on the surface of the paper (planar object). When printing a mark that clearly indicates the tag position, the tag position may be measured again immediately before printing. Further, tag position information may be written to the tag itself by a writer.

In this embodiment, the terahertz wave is focused on the linear focal point. However, the terahertz wave is condensed at one point, and is sufficiently faster than the transport speed in the direction intersecting the transport direction (typically, the perpendicular direction). The focus may be scanned at a speed. Alternatively, a planar terahertz detector (image sensor) may be used by irradiating a terahertz wave on a plane.

Further, in this embodiment, the terahertz wave generator and the detector are installed above and below the paper bundle 12 in which RFID is inserted, but the terahertz wave generator is provided inside the roller 13 which is a part of the paper transport mechanism, A detector may be incorporated.

For the terahertz wave generation method and detection method, a terahertz wave generated by irradiating the photoconductive antenna made of gallium arsenide or the like with a femtosecond laser may be used, but the following method may be used. . That is, a terahertz wave using parametric oscillation by a nonlinear optical effect may be used, or a method using a terahertz laser that generates a terahertz wave by injecting a current into a semiconductor having a quantum multiple well structure may be used.

(Example 2)
Next, Example 2 will be described. In the second embodiment, as shown in FIG. 4, the terahertz wave generator 10 and the terahertz wave detector 11 are placed above and below a part of the bundle of paper 12 in which the RFID tags stacked on the printing press paper feed tray 14 are inserted. Is installed.

Again, the terahertz wave emitted from the terahertz wave generator 10 forms a linear focus on the paper. Then, the terahertz wave transmitted through the paper is detected by the terahertz wave detection device 11. The terahertz wave detection device 11 includes, for example, terahertz wave detectors arranged in a line.

Also in this embodiment, since the terahertz wave is focused on the linear focus and the paper is moved to the printing machine side, the entire range of the paper is covered by the terahertz wave linear focus before the paper is taken into the printing machine. Will be scanned.

In this case, the terahertz wave is linearly collected on the uppermost surface of the bundle of paper 12 in which the bundled RFID tags are inserted, but even if the RFID tag exists on the second or third surface, A signal similar to 2 may be obtained. However, since the uppermost paper that is first taken into the printing press is moved to the left by the roller 13, the signal indicating the RFID tag of this paper appears for a moment and then disappears immediately. On the other hand, when the RFID tag is present on the linear focus of the RFID tag interleaving paper on the second surface and below, a signal indicating the presence of the RFID tag remains appearing.

For example, it is assumed that the paper feed speed is 10 centimeters per second, the width of the terahertz wavy line focus (width in the paper movement direction) is about 500 micrometers, and the size of the RFID tag is 500 micrometers. Then, the time for the RFID tag on the moving uppermost paper to cross the terahertz wavy focal point is about 10 milliseconds. Therefore, when a signal indicating the presence of the RFID tag is obtained for 10 milliseconds, it indicates the presence of the RFID tag on the uppermost paper. When a signal indicating the presence of the RFID tag for a longer time is obtained, the signal indicates the presence of the RFID tag in the paper on the second side and below. However, since the above estimate excludes scattering and diffraction of electromagnetic waves, a signal indicating the presence of the RFID tag is actually obtained for a longer time than the above estimate.

In this way, it is possible to detect only the RFID tag in the uppermost paper that is being taken into the printing press.

Two sets of terahertz wave generation / detection devices may be provided. Two sets of terahertz wave generator / detectors are installed at a certain distance (for example, 1 cm). Then, after the RFID tag is detected by the first detection device, if the RFID tag is detected by the second detection device after a certain period of time, it is determined that the RFID tag is in the uppermost paper. I will give you.

In this embodiment, by detecting the position of the RFID tag in a state where the bundle of paper 12 with the RFID tag inserted is still bundled, the detection information can be fed back to the printing machine earlier. Other points are the same as in the first embodiment.

(Example 3)
Example 3 will be described below. In the third embodiment, as shown in FIG. 5, the terahertz wave generation device 10 and the terahertz wave detection device 11 are installed on the top of the bundle of paper 12 in which the RFID tag stacked on the printing press paper feed tray 14 is inserted. . The terahertz wave emitted from the terahertz wave generator 10 forms a linear focus on the uppermost surface of the bundle of paper 12 in which the RFID tag is inserted. Then, the terahertz wave reflected by the bundle of paper 12 in which the RFID tag is inserted is detected by the terahertz wave detecting device 11 on the same side. Also here, the terahertz wave detection device 11 is, for example, one in which terahertz wave detectors are arranged in a line.

As the terahertz wave generation device 10 and the terahertz wave detection device 11, those described in the first embodiment can be used. Again, in order to increase the detection efficiency, an optical system including a lens and a mirror may be used before the terahertz wave detection device 11.

Even in this configuration, the reflectivity of the RFID tag and the paper with respect to the terahertz wave is different, so the presence of the RFID tag is calculated from the difference in the intensity and phase of the terahertz wave reflected by the paper and the terahertz wave reflected by the RFID tag. It is done. Therefore, when the RFID tag is present at one point on the linear focal point of the terahertz wave, it is possible to determine where the RFID tag is present on the linear focal point.

The processing after the detection of the position of the RFID tag and others are also performed in the same manner as described in the first embodiment.

(Example 4)
next. Example 4 will be described. In Example 4, a Michelson interferometer is constructed using a terahertz wave generator 20 and a terahertz wave detector 21, a terahertz wave half mirror 22, a terahertz wave mirror 23, and a movable terahertz wave mirror 24, as shown in FIG. To do. At this time, on one side of the Michelson interferometer, the lens 25 and the lens 26 are arranged on the paper 27 on which the RFID tag is inserted so as to focus.

For the terahertz wave generator 20, for example, a highly coherent light source such as BWO may be used, but a terahertz wave generated from a photoconductive antenna may be used. The terahertz wave generator 20 may include an optical system that emits a parallel beam.

The terahertz wave emitted from the terahertz wave generator 20 is divided into two beams by the terahertz wave half mirror 22. One is transmitted through the terahertz wave half mirror 22 and then reflected by the terahertz wave mirror 23, reaches the terahertz wave half mirror 22 again, is reflected here, and reaches the terahertz wave detector 21. The other is reflected by the terahertz wave half mirror 22, then focused on the paper 27 on which the RFID tag is inserted by the lens 25, and then returned to the parallel beam by the lens 26 again. Thereafter, the light is reflected by the movable terahertz wave mirror 24, reaches the terahertz wave half mirror 22 through the lens 26, the paper 27 in which the RFID tag is inserted, and the lens 25. Then, after passing through the terahertz wave half mirror 22, it merges with the terahertz wave that has passed through the other side, and is detected by the terahertz wave detector 21.

At this time, interference between terahertz waves occurs on the side that has passed through the paper 27 in which the RFID tag is inserted and the side that does not. For example, the movable terahertz wave mirror 24 is adjusted in advance with only the portion of the paper 27 into which the RFID tag is inserted, so that the terahertz wave detection sensitivity is maximized (intensifying interference). Then, when the paper 27 with the RFID tag inserted is moved using the roller 28, the interference condition changes when the RFID tag reaches the terahertz wave focal portion, and the value detected by the terahertz wave detector 21 changes. To do. That is, a phase change is detected. Thereby, the position of the RFID tag can be obtained.

Since the method of this embodiment uses terahertz wave interference, it is possible to detect the position of the RFID tag with higher sensitivity. The processing after the detection of the position of the RFID tag is the same as that described in the first embodiment.

FIG. 3 is a perspective view showing the arrangement of the detection apparatus according to the first embodiment that detects the position of the RFID tag in paper using transmitted terahertz waves. It is a schematic diagram which shows the mode of the signal of the case where there is no RFID tag in paper (a) and when it exists (b). It is the schematic diagram of the signal which showed the phase delay when the RFID tag is in paper and when it is not. FIG. 6 is a perspective view showing an arrangement of a detection apparatus according to a second embodiment that detects the position of an RFID tag in a bundle of paper bundled using transmitted terahertz waves. FIG. 10 is a perspective view showing an arrangement of a detection apparatus of Example 3 that detects the position of an RFID tag in paper using a reflected terahertz wave. FIG. 10 is a diagram illustrating an arrangement of a detection apparatus according to a fourth embodiment that detects the position of an RFID tag in paper using the arrangement of a Michelson interferometer.

Explanation of symbols

10, 20 Irradiation unit (Terahertz wave generator)
11, 21 detector (terahertz wave detector)
12 A bundle of planar objects (a bundle of paper with RFID tags inserted)
13, 28 Transport mechanism (roller)

Claims (10)

An apparatus for detecting an object embedded in a planar object,
A transport mechanism for transporting a planar object;
An irradiation unit for linearly irradiating the planar object to be conveyed with electromagnetic waves;
Among the electromagnetic waves, a detection unit for detecting an electromagnetic wave transmitted through the planar object or an electromagnetic wave reflected by the planar object;
A detection device comprising: 2. The detection device according to claim 1, wherein the irradiating unit irradiates the electromagnetic wave linearly on the planar object by condensing the linear focal point. The irradiating unit irradiates the planar object with electromagnetic waves linearly by condensing the electromagnetic wave at one point and scanning the focal point in a direction intersecting a conveyance direction of the planar object. 1. The detection device according to 1. 2. The detection device according to claim 1, further comprising changing means for changing a formation condition of an image formed on the surface of the planar object based on information on the electromagnetic wave detected by the detection unit. 2. The detection device according to claim 1, wherein the detection unit detects an object embedded in the planar object based on a change in at least one of an intensity and a phase of the electromagnetic wave. 2. The object detection device according to claim 1, wherein the irradiation unit and the detection unit constitute a Michelson interferometer. 7. The detection device according to claim 1, wherein the electromagnetic wave includes an electromagnetic wave including a frequency range of 30 GHz to 30 THz. When using the detection device according to any one of claims 1 to 7, when processing the surface of the planar object, based on the detection information of the detection device, the effect that the embedded object has on the processing step and A processing method comprising: changing processing conditions for reducing an influence of a processing step on the embedded object. 10. The detection / processing method according to claim 9, wherein the processing is image formation. 9. The processing method according to claim 8, wherein the object embedded in the planar object is an RFID tag that is an electronic component.