JPH0916703A - Optical information reader and method therefor and diffraction grating type information recording medium - Google Patents

Abstract

PURPOSE: To provide a diffraction grating type information recording medium, with which multilevel information can be recorded by increasing recording quantity per unit area, and to provide device and method for reading optical information with which the reading of information is speedily performed. CONSTITUTION: An optical information reader 6 is constituted for reading recorded information by vertically irradiating the recording unit of a diffraction grating type information recording medium 1, for which a single or combined diffraction gratings 4 specified by a grating pitch and a grating azimuth are defined as one recording unit and this unit is arranged along the scanning direction of a laser beam 7, with the laser beam 7 from a light source part 8, receiving diffracted light 9 from that irradiated section with an area sensor 10 and operating the grating pitch and grating direction or distribution pattern for each recording unit with a signal processing part 11, based on the detect signal.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diffraction grating type information recording medium in which arbitrary information is written as a plurality of diffraction gratings of a grating pitch and a grating orientation, and information written in the medium is optically read, The present invention relates to an optical information reading device and method for reading information written based on a grating pitch and a grating orientation or a distribution pattern of diffracted light.

[0002]

2. Description of the Related Art An information recording medium in which one-dimensional information such as a bar code is recorded on a plane or two-dimensional information is recorded as a holographic image, an information reading device therefor, and the like are widely used. In addition, various known techniques have been disclosed for a diffraction grating type information recording medium for recording high density information by using a fine diffraction grating as an information recording element, an information reading device thereof, and the like. For example, JP-A-6-76365 and JP-A-5-50788 show specific examples thereof. In Japanese Patent Laid-Open No. 6-76365, "Optical information recording medium and its information reading method", at least one cell composed of a diffraction grating is arranged on a flat substrate, and the cell is divided into n areas. By using each divided area as a mask selectively, for example, an optical information recording medium in which binary data indicating whether or not there is a diffraction grating is represented is manufactured. Also,
A method is disclosed in which one incident light is incident on the cell and the diffracted light emitted from each divided area of the cell is received by the same number of light receiving elements corresponding to the divided areas to reproduce information. On the other hand, the "card and card reader" disclosed in Japanese Patent Laid-Open No. 5-50788 encodes a plurality of diffraction grating patterns having the same or different grating orientations and spatial frequencies (grating pitches), and the coded diffraction grating pattern group. Of a diffracted light by irradiating the card with light of a specific wavelength and setting a plurality of light receiving elements set corresponding to the diffracted direction and the diffracted angle of the diffracted light of the diffraction grating pattern. Disclosed is an apparatus for identifying a diffraction grating based on the above, determining a code from a combination of the identified diffraction gratings, and reading information.

[0003]

All of the above-mentioned known techniques utilize a diffraction grating, but the former is one in which the cells of the diffraction grating are represented by binary data for each divided region, and the amount of information is limited. There is a problem. Further, by arranging n light receiving elements, it is possible to speed up the reading of information, but it is necessary to arrange the light receiving elements with high accuracy, and there is a problem that an error easily occurs in some cases. Also, in the latter case, since the diffraction grating pattern is coded, the amount of information is limited, and since a plurality of light receiving elements are used as in the former case, there are similar problems.

The present invention can record a large amount of information, can read a large amount of information quickly, and can accurately reproduce the information recorded on an information medium, and an optical information reading apparatus and method, and a diffraction grating type information recording. The purpose is to provide a medium.

[0005]

In order to achieve the above object, the present invention uses at least one diffraction grating as a recording unit and writes arbitrary information in the recording unit as a grating pitch and a grating orientation of the diffraction grating. An optical information reader applied to a diffractive grating type information medium, comprising: a light source unit for irradiating the recording unit with a light beam; and a grating pitch of the diffraction grating included in the recording unit on which the light beam is incident. And an area sensor having a two-dimensional light receiving surface for receiving diffracted light emitted in a specific direction according to the grating direction, and outputting a detection signal corresponding to the light receiving position of the diffracted light, and processing the detection signal. The optical reading device comprises a signal processing unit for reading the information written in the recording unit. More specifically, the light source unit is configured to generate a spot-like light beam including a recording unit composed of a plurality of diffraction gratings and irradiate the plurality of diffraction gratings of the recording units at a time, and the area sensor is It is characterized in that a plurality of diffracted lights emitted from the plurality of diffraction gratings at the same time are simultaneously received to enable reading of information in the recording unit. Further, the signal processing unit processes detection signals based on a plurality of diffracted lights from the area sensor to determine light receiving positions of the plurality of diffracted lights, and calculates a grating pitch and a grating orientation of each diffraction grating. It is characterized in that the information of the recording unit is read. Alternatively, the signal processing unit processes a detection signal based on a plurality of diffracted light from the area sensor, extracts a distribution pattern of light receiving positions of the plurality of diffracted light, and outputs information written in the recording unit. Characterized by reading. Further, the present invention is an optical information reading method applied to a diffraction grating type information recording medium in which arbitrary information is written in the recording unit as at least one diffraction grating as a recording unit as a grating pitch and a grating direction of the diffraction grating. That is, the first procedure of irradiating the recording unit with a light beam from the light source unit and emitting diffracted light in a specific direction according to the grating pitch and the grating direction of the diffraction grating, and the emitted diffracted light of the area sensor The second procedure for receiving the two-dimensional light receiving surface to generate detection signals corresponding to the respective diffracted light, and the information written in the recording medium after being processed by the second processing unit for generating the detection signals An optical information reading method including a third procedure for reading is featured. In the first procedure, a spot-shaped light beam including a recording unit composed of a plurality of diffraction gratings is applied to the recording unit to diffract light in a specific direction according to a grating pitch and a grating direction of each diffraction grating. In the second procedure, the plurality of diffracted lights are received by the two-dimensional light receiving surface of the area sensor to read the information for each recording unit. In the third procedure, the detection signal from the area sensor based on the diffracted light from the recording unit including a plurality of diffraction gratings is processed to individually determine the light receiving positions of the plurality of diffracted lights, and the grating of each diffraction grating is processed. It is characterized in that the pitch and the lattice direction are calculated and the information is read.
Further, in the third procedure, the detection signal from the area sensor based on the diffracted light from the recording unit composed of a plurality of diffraction gratings is processed to extract the distribution pattern of the light receiving positions of the plurality of diffracted light to extract the recording unit. It is characterized by reading the information written in. Further, the present invention is a diffraction grating type information recording medium capable of reproducing prewritten information by a spatial distribution of diffracted light generated by irradiation of a scannable light beam having a predetermined spot shape. Recording units included in a spot shape of the light beam are arranged along a scanning direction of the light beam, and the recording unit includes a set of a plurality of diffraction gratings, and a grating pitch of each diffraction grating and Information that is uniformly or collectively expressed by a grating direction is written, and the set of diffraction gratings receives the light beams at a time and collectively emits the light beams based on the grating pitch and the grating direction of each diffraction grating. A diffraction grating type information recording medium is formed which diffracts in different directions and enables reproduction of information according to the spatial distribution.

[0006]

By irradiating the diffraction grating type information recording medium with a light beam such as a laser beam, diffracted light specified by the grating pitch and the grating direction of the diffraction grating constituting the recording unit is emitted. The position of the emitted light is received by the two-dimensional light receiving surface of the area sensor, and the detection signal is processed by the signal processing unit to obtain the grating pitch and the grating orientation, and the diffraction grating is specified, so that the information of the recording unit is read. be able to. Also, the recording units are collectively irradiated with a spot-shaped light beam that includes the recording units composed of a plurality of diffraction gratings, and the two-dimensional light receiving surface of the area sensor receives a plurality of diffracted lights. It is possible to read the information for each recording unit by obtaining the grid pitch and the grid direction of or of the distribution pattern. Since a large number of diffraction grating groups of arbitrary shapes can be arranged in the recording unit, a large amount of information can be recorded.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. In this embodiment, a case where a laser beam is used as the light beam will be described. FIG. 1 is a schematic diagram showing an outline of a diffraction grating type information recording medium in which recording units made of a single diffraction grating are arranged in the scanning direction of a laser beam and an optical information reading device thereof, and FIG. 2 is a plurality of diffraction gratings. FIG. 3 to FIG. 7 are schematic views showing an outline of a diffraction grating type information recording medium in which recording units consisting of are arranged along the scanning direction of a laser beam and an optical information reading device thereof. It is a top view showing various examples.

As shown in FIG. 1, the diffraction grating type information recording medium 1 of the present embodiment has a metal film deposition plate 5 on which a metal film is vapor-deposited, which is formed on a support 5 such as a rectangular card. The reflective diffraction grating 4 is formed. The diffraction grating 4 is magnified and displayed in FIG. 2, and is formed of a predetermined grating pitch 2 and a grating orientation 3, and the diffraction grating 4 is a single recording unit that constitutes one recording unit. And the recorded information is specified by the lattice orientation 3. The recording medium of the present embodiment is composed of a large number of diffraction gratings 4 arranged in the scanning direction of the laser beam 7 (direction of arrow A in the figure). A diffraction grating manufacturing machine is generally used to form the diffraction grating 4. As the diffraction grating manufacturing machine, there are an exposure type using a laser and an electron beam drawing type.

On the other hand, the optical information reading device 6 includes a support (not shown) on which the diffraction grating type information recording medium 1 is mounted, a moving means (not shown) for moving the support in the direction of arrow A, and a moving means. The light source section 8 for irradiating the diffraction grating type information recording medium 1 with the laser beam 7 as an incident light and the diffracted light 9 emitted from the irradiation portion of the diffraction grating type information recording medium 1 are received to detect the coordinates of the light receiving position. It comprises an area sensor 10 having a two-dimensional light receiving surface, a signal processing unit 11 having a decoder for reproducing information by calculating the grating pitch and the grating direction of the diffraction grating 4 based on the detection signal from the area sensor 10.
In this embodiment, the laser light oscillation device that emits the laser beam 7 is adopted as the light source unit 8, but the present invention is not limited to this. For example, a light source unit having a bright line spectrum, a white light source unit, a light source unit outside the visible range such as X-rays, an oscillating wave such as a microwave, or the like may be used. In addition, the area sensor 10
A photodiode array, a phototransistor array, a photomultiplier tube, a CCD array, etc., which are arranged on a plane are applied. An X-ray camera is used when the light source unit is an X-ray, and an antenna or the like is used when the light source unit is a microwave.

The area sensor 10 is arranged at a position opposed to the diffraction grating type information recording medium 1, and when a laser beam is vertically incident on the surface of the diffraction grating type information recording medium 1 from the light source section 8, the irradiation portion of the diffraction grating 4 is irradiated. The diffracted light 9 is reflected from. In this case, the diffracted light 9 is reflected in the direction orthogonal to the lattice orientation 3 shown in FIG. Since the diffracted light 9 is received by the specific point P of the area sensor 10, the angles α and β shown in FIG. 1 are obtained from the coordinates of the specific point P on the area sensor 10 and the coordinates of the diffraction grating 4. In this case, since there is one diffraction grating 4, its coordinates are at the origin position. Therefore, the angles α and β are obtained by inputting the detection signal representing the coordinates of the specific point P to the signal processing unit 11, and since the diffracted light 9 is orthogonal to the lattice orientation 3, the lattice orientation can be easily adjusted to the angle β. Required to. Further, the diffraction angle θ of the diffracted light 9 can be easily obtained from the angle.
When the laser beam 7 is vertically incident on the diffraction grating type information recording medium 1, the grating pitch 2 is obtained by λ / sin θ. Where λ is the wavelength of the laser beam 7 and θ is the diffraction angle. As described above, the lattice pitch 2 can be obtained by obtaining θ. All of the above calculations are performed by the signal processing unit 11 based on the coordinates of the diffracted light 9 received by the area sensor 10. By scanning the laser beam 7 in the direction of arrow A and irradiating each diffraction grating 4, the emission direction of the diffracted light 9 from each recording unit is sequentially obtained by the area sensor 10 and the signal processing unit 11, and all the diffraction gratings are obtained. The grid pitch and grid orientation of 4 can be calculated. Therefore, the information recorded on the diffraction grating type information recording medium 1 can be reproduced.

Although FIG. 3 shows one diffraction grating 4, FIG. 4 shows a plurality of diffraction gratings 4a, 4b, 4c ... 4h having different grating pitches and grating directions as recording units 50. Shows the array.

As the recording unit for expressing the information of the diffraction grating type information recording medium 1, one diffraction grating 4 may be used and arranged along the scanning direction of the laser beam 7 as described above. The eight sets of the diffraction gratings 4a to 4h shown in FIG. 4 may be one recording unit 50. FIG. 5 shows an arrangement of a plurality of the recording units 50. This diffraction grating type information recording medium has recording units 50a, 5a.
0b, 50c ... Are arranged in the scanning direction and multi-valued information is recorded. As shown, for example, recording unit 5
0a is a set of 8 pieces having different grid pitches 2 and grid orientations 3, and multi-valued information can be recorded by these groups. Further, as shown in FIG. 5, the recording units 50a, 50b, 50c, ... Are composed of recording units in which diffraction gratings 4a, 4b having different shapes are combined, so that complex multivalued information can be recorded. The reading device applied to such a diffraction grating type information recording medium 1 needs to read information collectively for each recording unit 50. Therefore, as shown in FIG. 2, the laser beam needs to be a wide laser beam 7a having an appropriate spot shape in the scanning direction.

On the other hand, in FIG. 6, the diffraction gratings 4a to 4h are collectively arranged in a direction orthogonal to the scanning direction of the laser beam 7.
FIG. 7 shows a plurality of recording units 60, and a plurality of the recording units 60 are arranged in the scanning direction of the laser beam 7.
Also in this case, the diffraction grating type information recording medium 1 has the recording unit 60.
A plurality of a, 60b ... Are arranged in the scanning direction. In this case, the spot shape of the laser beam 7a needs to be vertically long, and is schematically shown in FIG.

FIG. 2 shows an optical information reading device 6a in which a plurality of diffraction gratings 4 as shown in FIGS. 5, 6 and 7 are used as one recording unit 50, 60. The structure of the apparatus is basically the same as shown by the same reference numeral as in FIG. 1, but as described above, the laser beam 7a has a spot shape capable of collectively irradiating one recording unit. The diffraction grating type information recording medium 1a is composed of recording units 60 arranged in the scanning direction (viewed by the arrow A). When the recording medium 60 is irradiated with the wide laser beam 7a, the recording unit 6
Diffracted lights 9a, 9b, 9c ... In different directions from the plurality of diffraction gratings 4a, 4b.
Are emitted all at once. Therefore, the diffracted light 9a, 9b, 9c
Are received at different coordinate positions of the area sensor 10. In this case, when the size of the recording unit is smaller than the size of the area sensor (in other words, when the spot size of the laser beam is sufficiently small), the coordinates of the recording unit 60 are assumed to be the origin position. Each diffracted light 9a, 9b, 9c on the area sensor 10 ...
The grating pitch and grating direction of the corresponding diffraction grating can be calculated based on the light receiving position of.
The information written in 0 can be read and specified. However, the recording unit 6 shown in FIGS.
When the size of 0 is larger than the size of the area sensor and cannot be ignored, the coordinates cannot be assumed to be the origin position. Therefore, in this case, the area sensor 10
The written information is read based on the distribution pattern of the diffracted light developed above. As described above, the written multi-valued information can be read. In any case, the present invention reads the information written in the recording unit by the spatial distribution of a plurality of diffracted lights generated by the irradiation of the laser beam.

As described above, the diffraction grating type information recording media 1 and 1a of this embodiment can record arbitrary multi-valued information by combining a plurality of diffraction gratings as a recording unit, and at the same time, this embodiment. The multi-valued information can be read by calculating the grating pitch, the grating orientation or the distribution pattern by the optical information reading devices 6 and 6a. In the above description, the diffraction grating type information recording mediums 1 and 1a in which multi-valued information is recorded are adopted, but of course the invention is not limited to these.

[0016]

According to the present invention, the following remarkable effects can be obtained. 1) The recording density is increased by adopting a diffraction grating type information recording medium in which diffraction gratings having different grating pitches and grating orientations are vertically or horizontally combined to form one recording unit and arranged in the scanning direction. The amount of recording per unit area can be increased. Therefore, it is applied as an information recording medium that needs to record a large amount of information. 2) Since the amount of information that can be recorded at one time is large, the recording area per unit recording amount can be reduced. 3) Information reading is calculated based on the light receiving point of the diffracted light developed on the area sensor, and accurate reproduction is possible. 4) Since multi-valued information can be read collectively for each recording unit, the reading speed can be improved as a whole.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a configuration of an optical information reading device used for reading information from a diffraction grating type information recording medium having a single diffraction grating as a recording unit.

FIG. 2 is a schematic diagram showing a configuration of an optical information reading device used to read information from a diffraction grating type information recording medium having a combination of a plurality of diffraction gratings as one recording unit.

FIG. 3 is a plan view showing one diffraction grating which constitutes a recording unit of the diffraction grating type information recording medium.

FIG. 4 is a plan view showing a diffraction grating type information recording medium in which the diffraction gratings of FIG. 3 are arranged in a scanning direction of a laser beam.

5 is a plan view showing a diffraction grating type information recording medium formed by arranging the plurality of diffraction gratings shown in FIG. 4 as one recording unit along the scanning direction.

FIG. 6 is a plan view showing a diffraction grating type information recording medium in which a set of a plurality of diffraction gratings arranged at right angles to a scanning direction is used as one recording unit.

7 is a plan view of a diffraction grating type information recording medium in which a plurality of recording units of FIG. 6 are arranged in the scanning direction.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Diffraction grating type information recording medium 1a Diffraction grating type information recording medium 2 Grating pitch 3 Grating direction 4 Diffraction grating 4a Diffraction grating 4b Diffraction grating 4c Diffraction grating 4d Diffraction grating 4e Diffraction grating 4f Diffraction grating 4g Diffraction grating 4h Diffraction grating 5 6 Optical Information Reader 6a Optical Information Reader 7 Laser Beam 7a Laser Beam 8 Light Source 9 Diffracted Light 9a Diffracted Light 9b Diffracted Light 9c Diffracted Light 10 Area Sensor 11 Signal Processor 50 Recording Unit 50a Recording Unit 50b Recording Unit 50c Recording unit 60 Recording unit 60a Recording unit 60b Recording unit 60c Recording unit

Continuation of front page (51) Int.Cl. ⁶ Identification number Office reference number FI Technical display location G06K 19/06 G02B 27/00 P // G11B 7/00 G06K 19/00 C

Claims (9)

[Claims] 1. An optical information reading device applied to a diffraction grating type information medium in which at least one diffraction grating is used as a recording unit and arbitrary information is written in the recording unit as a grating pitch and a grating direction of the diffraction grating. A light source unit that irradiates the recording unit with a light beam, and receives diffracted light that is emitted in a specific direction according to the grating pitch and the grating direction of the diffraction grating included in the recording unit into which the light beam is incident. An area sensor having a two-dimensional light receiving surface for outputting a detection signal corresponding to the light receiving position of the diffracted light, and a signal processing unit for processing the detection signal and reading the information written in the recording unit are provided. An optical information reading device characterized by: 2. The light source unit is configured to generate a spot-like light beam including a recording unit composed of a plurality of diffraction gratings and irradiate the plurality of diffraction gratings of the recording unit at a time, and the area sensor is The optical information reading device according to claim 1, wherein a plurality of diffracted lights emitted from the plurality of diffraction gratings at the same time are simultaneously received to enable reading of information of the recording unit. 3. The signal processing unit processes detection signals based on a plurality of diffracted lights from the area sensor to determine light receiving positions of the plurality of diffracted lights, and determines a grating pitch and a grating direction of each diffraction grating. The optical information reading device according to claim 2, wherein the information is calculated and the information of the recording unit is read. 4. The signal processing unit processes a detection signal based on a plurality of diffracted light from an area sensor, extracts a distribution pattern of light receiving positions of the plurality of diffracted light, and writes the distribution pattern in the recording unit. The optical information reading device according to claim 2, which reads information. 5. An optical information reading method applied to a diffraction grating type information recording medium in which arbitrary information is written in the recording unit as at least one diffraction grating as a recording unit as a grating pitch and a grating direction of the diffraction grating. And
A first procedure of irradiating the recording unit with a light beam from a light source unit and emitting diffracted light in a specific direction according to a grating pitch and a grating direction of a diffraction grating, and the emitted diffracted light on a two-dimensional light receiving surface of an area sensor. An optical system including a second procedure for receiving detection light by the optical disc and generating a detection signal corresponding to each diffracted light, and a third procedure for processing the detection signal by a signal processing unit and reading the information written in the recording medium. Expression information reading method. 6. The first procedure comprises irradiating the recording unit with a spot-shaped light beam including a recording unit composed of a plurality of diffraction gratings, and irradiating the recording unit with a specific direction according to a grating pitch and a grating direction of each diffraction grating. A plurality of diffracted light beams are emitted, and the plurality of diffracted light beams are received by the two-dimensional light receiving surface of the area sensor to enable reading of information for each recording unit in the second step. 5. Optical information reading method of 5. 7. The third step is to process a detection signal from an area sensor based on diffracted light from a recording unit composed of a plurality of diffraction gratings to individually determine light receiving positions of the plurality of diffracted lights, and to determine each diffracted light. 7. The optical information reading method according to claim 6, wherein information is read by calculating a grating pitch and a grating orientation of the grating. 8. The third procedure processes a detection signal from an area sensor based on diffracted light from a recording unit including a plurality of diffraction gratings to extract a distribution pattern of light receiving positions of the plurality of diffracted light. 7. The optical information reading method according to claim 6, wherein the information written in the recording unit is read. 9. A diffraction grating type information recording medium capable of reproducing prewritten information by a spatial distribution of diffracted light having a predetermined spot shape and generated by irradiation of a scannable light beam. Recording units included in the spot shape of the light beam are arranged along a scanning direction of the light beam, and the recording unit is composed of a set of a plurality of diffraction gratings and has a grating pitch of each diffraction grating. And information that is collectively expressed by the grating direction is written, and the set of diffraction gratings receives the light beams collectively and changes the light beams in different directions based on the grating pitch and the grating direction of each diffraction grating. A diffraction grating type information recording medium characterized by being diffracted and capable of reproducing information according to its spatial distribution.