JP2722984B2 - Diffraction grating detector - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for detecting a diffraction grating, and more particularly to a diffraction grating detection device which is particularly suitable for detecting a diffraction grating formed at least in part by a non-transparent member. is there.

[0002]

2. Description of the Related Art As a method of printing images such as characters and characters on booklets and cards, there is a method using an intermediate transfer medium. An example of this method will be briefly described in a case where a long film is used as an intermediate transfer medium.

[0003] An adhesive layer is formed on one surface of a long film used as an intermediate transfer medium. When an image on the film is transferred to a booklet, a card, or the like, the adhesive layer is formed together with the image. It is transferred to booklets and cards. The film on which the adhesive layer is formed is first conveyed in the longitudinal direction, and is positioned and stopped at a position facing the transfer ribbon coated with paint. After the film is positioned, the thermal head heats the portion corresponding to the print pattern of the transfer ribbon, and the paint at the heated portion becomes an image, from which the adhesive layer of the film is formed from the transfer ribbon. Is transferred to When the image is transferred from the transfer ribbon to the film, the film is transported in the longitudinal direction again, positioned and stopped at a position facing a booklet or a card, and the image on the film is heated and pressed by a transfer roll or the like. Then, the adhesive layer is transferred to a booklet or a card, and one printing operation is completed.

When printing on a passport, a traveler's check, a driver's license, etc. by the above-described method, a mark for preventing forgery such as a pattern is transferred to the passport, the traveler's check, the driver's license, etc. together with the image. There is. When transferring the anti-counterfeit mark, a holographic grating is recorded on the film surface opposite to the surface on which the adhesive layer is formed, at intervals of the predetermined amount in the longitudinal direction of the film. A plurality of holographic marks are formed in advance. Then, when transferring an image or an adhesive layer from a film to a passport, a traveler's check, a license, etc., the image recorded on the holographic mark near the image to be transferred is converted to a passport, a traveler's check, a license, etc. by any means. Transfer at the same time.

In the transfer method using a film, as described above, it is necessary to position the film conveyed in the longitudinal direction at a position facing a transfer ribbon, a booklet, a card, and the like. Therefore, in order to reliably position the film, a plurality of marks or notches for position detection are provided on the film at equal intervals in the longitudinal direction, and the marks are provided at a position facing the transfer ribbon, booklet, card, or the like. It is desirable to detect notches and notches. And, as described above, since a plurality of holograms are already formed at equal intervals in the longitudinal direction of the film used for transferring the forgery prevention mark together, the hologram It is convenient if the position of the film is detected by detecting the position.

The holographic grating recorded on the holographic mark is, of course, a kind of diffraction grating. Therefore, if the holographic mark on the film can be detected as described above, it will be used in various fields. It is needless to say that the presence or absence of a diffraction grating (including a holographic grating) can also be detected, which is convenient, for example, for controlling the positioning of a reading unit approaching a holographic memory.

[0007]

In order to detect the presence or absence of the diffraction grating, a method of irradiating the diffraction grating with light and detecting the diffracted light from the diffraction grating can be considered. In this case, if the incident angle of the irradiation light with respect to the normal line of the diffraction grating and the emission angle with respect to the normal line of the diffraction light are set to be equal, the reflected light and the diffraction light emitted from the diffraction grating at an angle equal to the incident angle of the irradiation light If the incident angle of the irradiation light and the emission angle of the diffracted light are made different, the distinction between the reflected light and the diffracted light can be easily made.

However, since the exit angle of the diffracted light is determined only when the incident angle of the irradiation light is determined, both the incident direction of the irradiation light and the exit direction of the diffracted light have an angle with respect to the normal of the diffraction grating. If it is set so as to have it, it is necessary to adjust the position when installing the light emitting side of the irradiation light and the light receiving side of the diffracted light, and there is a problem that the adjustment becomes complicated.

In the case where at least a part of a diffraction grating to be detected is formed of a non-transparent member, such as a hologram on a film on which an adhesive layer of a color having a diffuse reflection property such as white or gray is formed. The light applied to the diffraction grating is reflected in all directions by the non-transparent portion, and generates reflected light different from the diffracted light. Therefore, when at least a part of the diffraction grating to be detected is formed of a non-transparent member, the directivity of the diffracted light is increased so that the diffracted light can be distinguished from the reflected light.
It is important to arrange the light receiving side of the diffracted light at a position corresponding to the directivity.

Further, when the directivity of the diffracted light is enhanced, a slight deviation of the direction of the diffraction grating in the plane in which the diffraction grating extends greatly affects the optical path of the diffracted light, and the diffracted light can be introduced to the light receiving side. Therefore, it is desirable to take measures to correct the optical path shift due to the shift of the direction of the diffraction grating and to surely guide the diffracted light to the light receiving side.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and a first object of the present invention is to detect the presence or absence of a diffraction grating, such as the detection of a hologram on a film used as an intermediate transfer medium. In addition, the present invention provides a diffraction grating detection device suitable for detecting the presence or absence of a diffraction grating at least partially formed of a non-transparent member. It is in. A second object of the present invention is to improve the directivity of the diffracted light and correct the optical path deviation due to the deviation of the direction of the diffraction grating to reliably guide the diffracted light to the light receiving side. It is to provide a diffraction grating detection device.

[0012]

According to a first aspect of the present invention, there is provided an apparatus for detecting a diffraction grating, comprising: a detection light having a single wavelength directed toward the diffraction grating; And a light receiving means for receiving the diffracted light from the diffraction grating irradiated with the detection light, wherein the light emitting means has an optical axis of the diffracted light parallel to a normal line of the diffraction grating. And the light receiving means is arranged in a direction parallel to the normal line and at a position on the diffraction grating on the normal line passing through the irradiation position of the detection light. I do.

In order to achieve the second object, according to the present invention, a light scattering means for scattering the diffracted light is provided on an optical path of the diffracted light. Further, the second
According to a third aspect of the present invention, an optical path correcting optical system for correcting the optical path of the diffracted light toward the light receiving means is provided on the optical path of the diffracted light. In the invention according to claim 4, the optical path correcting optical system is constituted by a conical conduit fiber. Further, in the invention according to claim 5, the optical path correcting optical system is constituted by a reflection mirror.

[0014]

According to the first aspect of the present invention, since the optical axis of the diffracted light is parallel to the normal of the diffraction grating and the light receiving means is on the normal of the diffraction grating passing through the irradiation point of the detection light. The diffracted light diffracted by the diffraction grating can be reliably received by the light receiving means. In addition, since the detection light output by the light emitting means has a single wavelength, the light intensity of the diffracted light diffracted by the diffraction grating by the irradiation of the detection light is smaller than the light intensity of the reflected light reflected by the diffraction grating. It becomes sufficiently strong, so that it is easy to distinguish the diffracted light from the reflected light, and the diffraction grating can be reliably detected.

Further, according to the present invention as set forth in claims 2 to 5, even if there is a shift in the direction of the diffraction grating in the plane on which the diffraction grating extends, the shift of the optical path caused by the shift is eliminated. This is advantageous in that the corrected diffraction light can be reliably guided to the light receiving means, and the diffraction grating can be reliably detected.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. First, a member on which a diffraction grating is formed will be described with reference to FIG. In FIG. 5, 1 is a transparent film, 1
1 is an image, and 13 is a hologram (corresponding to a diffraction grating).

The transparent film 1 is used as an intermediate transfer medium when an image is printed on a passport, a traveler's check, a license (neither is shown) or the like by a method using an intermediate transfer medium. The adhesive layer 16 is formed to be long and has a diffuse reflection color such as white or gray on one surface 15. The image 11 is, for example, transferred from a transfer ribbon (not shown) coated with a sublimable paint by heating a thermal head (not shown), and the surface 15 of the transparent film 1 on which the adhesive layer 16 is formed. Is formed. The image 11 is transferred to a passport, a traveler's check, a license, etc. together with the adhesive layer 16 by heating and pressing the transparent film 1 with a transfer roll (not shown).

The holographic mark 13 is a holographic grating (not shown) corresponding to a mark for preventing forgery, such as a pattern to be transferred to a passport, a traveler's check, a license, etc., together with the image 11. Is formed on the surface 17 of the transparent film 1 opposite to the surface 15 on which is formed. This holographic mark 13 is a transparent film 1
A plurality of transfer areas of one image 11 are formed on the transparent film 1 at equal intervals in the longitudinal direction X, one for each transfer area of one image 11. In a printing apparatus (not shown) using the transparent film 1 having such a configuration as an intermediate transfer medium, an image 11 from the transfer ribbon to the transparent film 1 is formed.
The transfer of the image 11 and the transfer of the image 11 from the transparent film 1 to a passport, a traveler's check, a license or the like are continuously and repeatedly performed while the transparent film 1 is transported in the longitudinal direction X.

Next, in the above-described printing apparatus, the diffraction according to one embodiment of the present invention, which is used for positioning and stopping the transparent film 1 at a place where a transfer ribbon, a passport, a traveler's check, a license or the like is provided. A schematic configuration of the grid detection device will be described with reference to FIG. In FIG. 1, the diffraction grating detection device of the present embodiment, which is indicated by the reference numeral 3, is disposed above a region where the hologram 13 of the transparent film 1 conveyed in the longitudinal direction X passes so as to face the surface 17 of the transparent film 1. It is provided with a laser light source 31 (corresponding to light emitting means), an optical fiber 35 (corresponding to light receiving means), and supporting frames 37 and 39.

The laser light source 31 outputs a single-wavelength laser beam L1 (corresponding to detection light) toward the surface 17 of the transparent film 1. The laser light source 31 includes an optical system such as a collimator lens for outputting a parallel laser beam L1. The optical fiber 35 receives the diffracted light L3 from the holographic mark 13 when the laser beam L1 is irradiated on the holographic mark 13 provided on the surface 17 of the transparent film 1 being conveyed.
Is incident from the end face 36 of the optical fiber 35 and guided into the inside thereof.

The support frame 37 supports the optical fiber 35, and the optical fiber 35 supported by the support frame 37, as shown in FIG. In the state where the light is irradiated upward, it is positioned at a position on the normal line Y passing through the irradiation position P1 (corresponding to the detection light irradiation position on the diffraction grating), and the optical axis S1 of the optical fiber 35 is
In a direction parallel to the normal Y of Support frame 39
Supports the laser light source 31. The laser light source 31 supported by the support frame 39 is
The direction in which the laser beam L1 is output is such that the optical axis S3 of the diffracted light L3 from 3 is parallel to the normal Y of the holographic mark 13.

In the diffraction grating detector 3 of this embodiment, as shown in FIG. 1, the distance M1 from the light emitting surface 32 of the laser light source 31 to the irradiation point P1 of the laser beam L1 on the surface 17 of the transparent film 1 is measured. The surface 17 of the transparent film 1
From the irradiation position P1 of the upper laser beam L1 to the optical fiber 3
The distance M3 to the end face 36 of No. 5 is set relatively long.

In the diffraction grating detecting device 3 of this embodiment having such a configuration, when a laser beam L1 of a parallel light beam is output from the laser light source 31, the laser beam L1 is applied to the surface 17 of the transparent film 1 being conveyed. Irradiated on top. When the holographic mark 13 approaches the optical axis S5 (FIG. 1) of the laser beam L1 while the transparent film 1 is being conveyed, the holographic mark 13 is irradiated with the focused laser beam L1. When the holographic mark 13 is irradiated with the laser beam L1, the holographic mark 13 and the transparent film 1 are transparent. Therefore, most of the laser beam L1 transmits the transparent film 1 from the surface 17 side to the surface 15 side.

However, a part of the laser beam L1 is reflected at the irradiation point P1 on the hologram 13 and reflected light emitted from the hologram 13 at an angle equal to the angle between the optical axis S5 of the laser beam L1 and the normal Y. L5 (FIG. 1). Further, since the adhesive layer 16 formed on the surface 15 of the transparent film 1 has a non-transparent color, the laser beam L1 transmitted to the surface 15 side is irregularly reflected in all directions by the adhesive layer 16, and the irregularly reflected light (see FIG. (Not shown), a blurred bright portion is generated at the irradiation position P3 (FIG. 1) on the adhesive layer 16. Further, a part of the laser beam L1 is
The diffracted light L3 having an optical axis S3 oriented parallel to the normal Y of the hologram 13 is generated by being diffracted at the irradiation point P1 on the hologram mark 13.

Of the reflected light L5, the distance M3 from the irradiation point P1 of the laser beam L1 on the surface 17 of the transparent film 1 to the end face 36 of the optical fiber 35 is set to be long. No light is incident on 36. In addition, the irregularly reflected light of the laser beam L1 irregularly reflected in all directions on the adhesive layer 16 causes the end face 36 of the optical fiber 35 to irradiate the irradiation point P3 on the adhesive layer 16 at the time when the laser beam L1 is irradiated onto the hologram 13. Since it is not located on the normal Y of the passing hologram 13, the optical fiber 35
Is hardly incident on the end face 36.

On the other hand, since the diffracted light L3 has an optical axis S3 oriented parallel to the normal Y of the hologram 13, the optical fiber positioned at the normal on the hologram 13 passing through the irradiation point P1 35 reaches the end face 36, and the end face 36
From the optical fiber 35.

A part of the diffracted light L3 incident from the end face 36 of the optical fiber 35 is guided to a light-receiving element (not shown) via the optical fiber 35, and the diffracted light L3 incident on the optical fiber 35 here. The electric signal value is converted into an electric signal having a value corresponding to the amount of light, and the electric signal value is compared with a predetermined threshold value by a comparator (not shown) at the next stage. Then, when the electric signal value exceeds the threshold value, the control circuit (not shown) of the next stage starts the optical fiber 35.
It is assumed that the diffracted light L3 has been detected in
The transport means (not shown) for transporting the transparent film 1 in the longitudinal direction X is controlled, the transport of the transparent film 1 is stopped, and the transparent film 1 is positioned at a predetermined position in the longitudinal direction X.

As described above, in the diffraction grating detecting device 3 of the present embodiment, the single-wavelength laser beam L1 output from the laser light source 31 is irradiated onto the hologram 13 of the transparent film 1, and the diffracted light L3 generated by this is irradiated. Is incident on the end face 36 of the optical fiber 35 to detect the presence or absence of the holographic mark 13. In particular, the laser light source 31 is oriented so that the optical axis S3 of the diffracted light L3 is parallel to the normal Y of the holographic mark 13. While arranging, the optical fiber 35 is
3 was placed in a direction parallel to the normal line Y at a position on the normal line Y passing through the irradiation position P of the laser beam L1.

For this reason, irregularly reflected light of the laser beam L 1 generated by irregular reflection on the adhesive layer 16 and the holographic mark 13
Reflected light L5 of the laser beam L1 generated by the above reflection
Is not incident on the end face 36 of the optical fiber 35 and the diffracted light L3 from the holographic mark 13 is
6, the holographic mark 13 formed on the transparent film 1 can be reliably detected.
Since the optical fiber 35 is located at the position where the diffracted light L3 having the optical axis S3 parallel to the normal Y of the holographic mark 13 is incident, the light of the laser light source 31 is set when the diffraction grating detection device 3 is assembled and installed. It is only necessary to adjust the angle between the axis S5 and the normal Y, and there is no need to adjust the optical fiber 35, and the adjustment work can be simplified.

Further, in the diffraction grating detecting device 3 of the present embodiment, since the single-wavelength laser beam L1 is irradiated onto the hologram 13 of the transparent film 1, non-single-wavelength light is used as the detection light. Compared with the case, the directivity of the diffracted light L3 from the holographic mark 13 can be increased, which is advantageous in that the holographic mark 13 formed on the transparent film 1 can be reliably detected.

If the direction of the holographic mark 13 shifts in the plane in which the transparent film 1 extends, the optical path of the diffracted light L3 shifts in the paper direction in FIG. . Therefore, as shown in FIG. 2, for example, a light scattering means 33 is provided on the optical path of the diffracted light L3, and when the light passes through the light scattering means 33, the diffracted light L3 is scattered. 3, a conical conduit fiber 34 having a truncated conical shape on the optical path of the diffracted light L3 (a conical conduit rod lens may be used) as shown in FIG. The optical path of the diffracted light L3 may be bent toward the end face 36 of the optical fiber 35 by passing through the fiber 34. Here, specific examples of the light scattering means 33 include frosted glass, polished glass, non-Newton glass, and a plastic plate whose surface is roughened or embossed.

Further, instead of the above-mentioned conical conduit fiber 34, as shown in FIG. 4, a reflecting mirror 38 for condensing light is disposed at a position corresponding to the optical path where the diffracted light L3 is shifted, and the optical path is shifted. The diffracted light L3 may be reflected by the reflection mirror 38 and incident on the light receiving element 35A.
Here, specific examples of the reflecting mirror 38 include a conical mirror, a bell-shaped mirror such as a parabolic mirror, an elliptical mirror, and an involute mirror, and a spherical mirror. In FIG. 4, 31A is a laser diode, 31B is a collimator lens unit, and in the diffraction grating detection device 3 shown in FIG. 4, the light receiving element 35A corresponds to a light receiving means.

Further, in this embodiment, a laser light source is used as the light emitting means. However, any other light source that outputs light other than laser light may be used as long as it outputs light of a single wavelength. If the light source cannot output light of a focused light beam to a certain extent, a light collecting means such as an aperture lens may be interposed between the light emitting means and the transparent film. In this embodiment, an optical fiber is used as the light receiving means. However, a light receiving element such as a pin photodiode may be used, and the distance between the light receiving means and the hologram is equal to the incident angle of the detection light. If the configuration can be such that the emitted reflected light is not detected, an arbitrary distance can be set regardless of the distance between the light emitting means and the hologram.

In this embodiment, a transparent film on which an adhesive layer of a color having a diffuse reflection property is formed as an intermediate transfer medium used when printing an image of a character, a character, or the like on a booklet, a card, or the like. Although the case of detecting the above holographic mark has been described, the diffraction grating detection device of the present invention is not limited to such a holographic mark at least partially formed of a non-transparent member, for example, other than a holographic memory or a holographic grating. It goes without saying that the present invention is applicable to the detection of a diffraction grating and various diffraction gratings formed entirely of a transparent member or a non-transparent member.

[0035]

As described above, according to the present invention, there is provided an apparatus for detecting a diffraction grating, comprising: a light emitting means for outputting a detection light of a single wavelength to the diffraction grating; Light receiving means for receiving the diffracted light from the diffraction grating, wherein the light emitting means is disposed in a direction in which the optical axis of the diffracted light is parallel to the normal to the diffraction grating, and the light receiving means Since it is configured to be disposed in a direction parallel to the normal line and at a position on the normal line passing through the irradiation position of the detection light on the diffraction grating, the presence or absence of the diffraction grating can be easily detected. In addition, it is possible to provide a device configuration that can be easily adjusted at the time of assembling and installing, and in particular, it can be suitable for detecting the presence or absence of a diffraction grating at least partially formed of a non-transparent member. .

[Brief description of the drawings]

FIG. 1 is an explanatory diagram illustrating a schematic configuration of a diffraction grating detection device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a schematic configuration of a diffraction grating detection device according to another embodiment of the present invention.

FIG. 3 is an explanatory diagram showing a schematic configuration of a diffraction grating detection device according to still another embodiment of the present invention.

FIG. 4 is an explanatory diagram showing a schematic configuration of a diffraction grating detection device according to a modification of the embodiment shown in FIG. 3;

FIG. 5 is a plan view showing a transparent film on which a plurality of holographic marks are formed.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 13 Holographic mark (diffraction grating) 16 Adhesion layer (non-transparent member) 3 Diffraction grating detection device 31 Laser light source (light emitting means) 31A Laser diode (light emitting means) 31B Collimator lens unit (light emitting means) 33 Light scattering means 34 Conical conduit fiber 35 Optical fiber (light receiving means) 35A Light receiving element (light receiving means) L1 Laser beam (detection light) L3 Diffracted light S1 Optical fiber optical axis S3 Diffractive optical axis P1 Laser beam irradiation point (detection light irradiation point on diffraction grating) Y Hologram Normal

Claims (5)

(57) [Claims] 1. An apparatus for detecting a diffraction grating, comprising: a light emitting means for outputting a detection light of a single wavelength toward the diffraction grating; and receiving a diffraction light from the diffraction grating irradiated with the detection light. The light emitting means is disposed in a direction in which an optical axis of the diffracted light is parallel to a normal line of the diffraction grating, and the light receiving means is in a direction parallel to the normal line, and A diffraction grating detection device, wherein the diffraction grating detection device is provided at a position on a normal line on the diffraction grating that passes through the irradiation position of the detection light. 2. The diffraction grating detection device according to claim 1, wherein a light scattering means for scattering the diffracted light is provided on an optical path of the diffracted light. 3. The diffraction grating detection device according to claim 1, wherein an optical path correcting optical system for correcting the optical path of the diffracted light toward the light receiving means is provided on the optical path of the diffracted light. 4. The diffraction grating detection device according to claim 3, wherein the optical path correcting optical system is constituted by a conical conduit fiber or a conical conduit rod lens. 5. The diffraction grating detecting device according to claim 3, wherein said optical path correcting optical system is constituted by a reflection mirror.