JPH055855A - Optical scanner - Google Patents

Abstract

PURPOSE:To eliminate the noise to draw scanning lines in many directions by changing the position and the angle of a mirror. CONSTITUTION:In an optical scanner provided with a laser light source, a beam shaping optical system which shapes light emitted from the laser light source, a hologram disk which scans the shaped laser light, a mirror optical system which reflects, separates, and condenses the scanned light, and a photodetector which irradiates a bar code with the scanned light to detect the reflected light, holograms A and B are formed which have space frequencies different from each other so that angles of diffraction of scanned light which is diffracted and scanned on the opposite sides in the incidence direction of laser light to the hologram disk 3 are different from each other, and a mirror 8a is arranged in a position corresponding to the angle of diffraction due to one hologram A out of holograms A and B having different space frequencies, and a mirror 8b is arranged in a position corresponding to that due to the other hologram B.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical scanning device for a laser bar code reader.

[0002]

2. Description of the Related Art A conventional optical scanning device is shown in FIG. 6 as a first conventional example. This is a laser light source 1, a shaping optical system 2 for beam shaping the light emitted from the laser light source 1, a hologram disc 3 for scanning the beam shaped laser light, and a reflection of the scanned scanning light. , A mirror optical system 4 for separating and condensing light, and a photodetector 5 for irradiating the barcode surface with the scanning light and detecting the reflected light. In this case, the shaping optical system 2 includes two beam shaping lenses 6 and a deflecting mirror 7 for changing the optical path. Further, the hologram disk 3 is formed with a plurality of holograms 3a. Further, the mirror optical system 4 includes a plurality of mirrors 8 arranged around the hologram disk 3, a perforated mirror 9, and a condenser lens 10.

In such a configuration, the laser light emitted from the laser light source 1 is beam-shaped by the beam-shaping lens 6, passes through the central hole 9a of the perforated mirror 9, is reflected by the mirror 7, and is rotated. The light enters perpendicularly to the hologram 3a surface of the hologram disc 3. Then, the beam incident on the hologram 3a is diffracted from the back surface side thereof and emitted to become scanning light, and the scanning light is reflected by a mirror 8 arranged in the surroundings and advances upward. , Thereby drawing the scanning lines 11 in various directions intersecting each other. Therefore, the scan line 1
A bar code 12 for reading is placed on the surface 1 to scan the surface thereof, thereby reading information. Then, the reflected light from the surface of the bar code 12 follows the path in the opposite direction to the path described above, and again the hologram disc 3
Through the mirror 7, and this time, is reflected by the mirror surface 9b of the perforated mirror 9 and condensed by the condenser lens 10 and detected by the photodetector 5, whereby the surface of the bar code 12 is described. It becomes possible to read and decode the stored information.

A second conventional example is Japanese Patent Laid-Open No. 58-58.
There is one disclosed in Japanese Patent No. 1119. this is,
The principle of reading can be considered to be almost the same as the case of the above-mentioned first conventional example in that a hologram disc having a plurality of holograms formed thereon is used and rotated to generate a scanning line. In this case, by making each hologram lens in the hologram group slightly decentered, the scanning lines in each direction can be used as a plurality of substantially parallel raster scanning lines.

Further, as a third conventional example, Japanese Patent Publication No. 56-56
There is one disclosed in Japanese Patent Publication No. 21132. This does not use the hologram discs used in the above-mentioned two conventional examples, but instead of the fixed mirror group having a plurality of reflecting surfaces arranged on the circumference and the center of the circumference of the fixed mirror group. It is composed of a rotating mirror that reflects the rotating and incident light beam toward the fixed mirror group, and thereby multi-directional scanning lines can be drawn.

[0006]

In the case of the first conventional example,
As shown in FIG. 5, when the hologram disk 3 is vertically incident, diffracted light K (scanning line) is generated in two directions symmetrical to the incident line. In the case of the normal scanning method, the scanning lines in various directions are drawn one after another in time series, so that there is no case where two or more scanning lines are present at the same time. There is a risk of drawing two scanning lines Ka and Kb. FIGS. 7A and 7B show the states of the signal waveforms a and b when such two scanning lines are detected by the photodetector 5. Thus, when two scanning lines are present at the same time, the photodetector 5 also detects reflected light from the object on the other scanning line, and the combined signal waveform c is obtained as shown in FIG. 7C. Therefore, there is a problem that the signals of the two scanning lines become noises with respect to the signals of the other scanning lines.

Further, in the case of the second conventional example, an example of scanning lines in two directions intersecting with each other is described, but a method in the case of disposing a mirror around the entire circumference of the hologram disk is mentioned. Absent. In general, it is necessary to emit scan lines in all directions in order to improve the reading performance of the barcode, and it is advantageous to arrange a mirror around the entire circumference of the hologram disc for that purpose, but It does not describe how to solve the problem in case.

Further, in the case of the third conventional example, a rotating mirror is used instead of the hologram disk. However, in this case, since it has an asymmetrical shape, a sound due to wind is generated or it is rotated. There is a problem that the number cannot be increased. Further, the hologram disc cannot perform raster scanning or scanning for changing the focal position. Further, there is a problem that the received light intensity is small because a large area cannot be taken due to windage loss or the like, and the received light intensity becomes small as the optical path length becomes long. If the rotating mirror is changed to a polygon, it is difficult to draw a scanning line in any direction because the scanning angle cannot be widened.If it is drawn, the scanning line can be drawn at a point far from the polygon. It is necessary to divide, and the whole optical system becomes large.

[0009]

According to a first aspect of the present invention, there is provided a laser light source, a shaping optical system for beam-shaping the light emitted from the laser light source, and a hologram disk for scanning the beam-shaped laser light. And a mirror optical system for reflecting, separating, and condensing the scanned scanning light, and a photodetector for irradiating the scanning light on a barcode and detecting the reflected light. A hologram having different spatial frequencies is formed so that the diffraction angles of the scanning light diffracted and scanned on the opposite side to the incident direction of the laser light on the disk are different from each other. A mirror was arranged at a position corresponding to the diffraction angle of one hologram, and a mirror was arranged at a position corresponding to the diffraction angle of the other hologram.

According to a second aspect of the invention, a laser light source,
A shaping optical system for beam shaping the light emitted from the laser light source, a hologram disk for scanning the beam shaped laser light, and a mirror optical system for reflecting, separating and condensing the scanned scanning light, In an optical scanning device provided with a photodetector for irradiating the barcode with the scanning light and detecting the reflected light, the scanning light diffracted and scanned on the opposite side to the incident direction of the laser light on the hologram disk. Holograms having different spatial frequencies are formed so that the diffraction angles are different from each other, and one of the two scanning lights generated by the one hologram is used for signal reading and the other scanning light is used. In order not to be used for signal reading, the mirrors at the positions for reflecting the two scanning lights are arranged so as to have different angles.

According to a third aspect of the invention, a laser light source is provided,
A shaping optical system for beam shaping the light emitted from the laser light source, a hologram disk for scanning the beam shaped laser light, and a mirror optical system for reflecting, separating and condensing the scanned scanning light, In an optical scanning device provided with a photodetector for irradiating the barcode with the scanning light and detecting the reflected light, the scanning light diffracted and scanned on the opposite side to the incident direction of the laser light on the hologram disk. Holograms having different spatial frequencies with different diffraction angles were formed, and the mirror was arranged only on one scanning light side of the two scanning lights generated by the one hologram.

[0012]

According to the first aspect of the invention, since each hologram has different spatial frequencies and the mirrors are arranged at the positions corresponding to the different diffraction angles, two scanning lines are generated at the same time. This will prevent the signal from becoming sloppy or noisy.

According to the second aspect of the invention, since the mirrors are arranged at different angles corresponding to the diffraction angle, the same effect as that of the first aspect of the invention can be obtained.

According to another aspect of the present invention, the mirror is disposed only on one scanning light side of the scanning lights having different diffraction angles obtained by passing through the holograms having different spatial frequencies. By using only one of the two symmetrical scanning lines generated by vertically entering the hologram for scanning, the same effect as that of the invention according to claim 1 can be obtained.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. 1 (a) (b) and 2. Regarding the overall configuration of the optical scanning device and its reading operation, the first conventional example (see FIG.
The description is omitted here, and the same reference numerals are used for the names of the same parts.

Here, the hologram disks 3 as shown in FIG. 2 are different so that the diffraction angles of the scanning light diffracted and scanned on the opposite side to the incident direction of the laser light on the hologram disk 3 are different from each other. Holograms A and B having spatial frequencies are formed. Further, as shown in FIG. 1A, a mirror 8a is arranged at a position corresponding to the diffraction angle of one hologram A having different spatial frequencies, and as shown in FIG. 1B, the other hologram B is used. The mirror 8b is arranged at a position corresponding to the diffraction angle.

In such a structure, the corresponding mirror 8 is inserted by interposing the incident line 13 incident on the hologram disk 3.
FIG. 1 shows a specific example in which the positions a and 8b are shifted.
A description will be given based on (a) and (b). Now, as shown in FIG. 1A, when the incident line 13 is made incident on the position corresponding to the hologram A, the scanning light 14 diffracted by this is reflected by the mirror 8a, and then used as a reading beam. However, the other diffracted scanning light 15 is not reflected because the position of the mirror 8b is displaced with respect to the diffraction angle, and thus is not used as a reading beam. On the other hand, as shown in FIG. 1B, when the incident line 13 is made incident on the position corresponding to the hologram B, the scanning light 15 diffracted by this is reflected by the mirror 8b and then used as a reading beam. However, the other diffracted scanning light 14 is not reflected because the position of the mirror 8a is displaced with respect to the diffraction angle, and thus is not used as a reading beam.

As described above, the holograms A and B have different spatial frequencies, and the mirrors 8a and 8b are arranged at the positions corresponding to the different diffraction angles.
The scanning lights 14 and 15 of the book are not generated. Therefore, since the read signal does not become dull or a noisy signal does not occur, it is possible to always stably draw multi-directional scanning light and perform accurate reading.

Next, a second embodiment of the present invention is shown in FIG.
A description will be given based on (b). Here, hologram A,
One scanning light 14 (or scanning light 15) of the two scanning lights generated by B is used for signal reading,
The angles of the mirrors 8a and 8b at which the two scanning lights 14 and 15 are respectively reflected are changed so that the other scanning light 15 (or the scanning light 14) is not used for signal reading. It was done. The hologram disk 3 has the same structure as that shown in FIG.

In such a structure, the corresponding mirror 8 is inserted by interposing the incident line 13 incident on the hologram disk 3.
FIG. 1 shows a specific example in which the angles a and 8b are shifted.
A description will be given based on (a) and (b). As shown in FIG. 3A, when the incident line 13 is incident on the position corresponding to the hologram A, the scanning light 14 diffracted by the incident line 13 is reflected by the mirror 8 a and then emitted from the inside of the housing 16. Then, the other diffracted scanning light 15 is not emitted from the housing 16 to the outside because the angle of the mirror 8b is displaced from the diffraction angle. The inner wall of the housing 16 is made black so as not to affect the reading of signals. On the other hand, FIG.
As shown in (b), when the incident line 13 is made incident on the position corresponding to the hologram B, the scanning light 15 diffracted by the incident light 13 is reflected by the mirror 8b and emitted to the outside of the housing 16, and then read. The other diffracted scanning light 14 used as a beam is reflected by the mirror 8 with respect to the diffraction angle.
Since the angle a is arranged so as to be displaced, it is not emitted from the housing 16 to the outside, so that the scanning light 14 is absorbed by the inner wall of the housing 16 so as not to be used as a reading beam. You can Therefore, in the case of the present embodiment as well, two scanning lines 14 and 15 do not occur at the same time, and the same effect as in the case of the first embodiment described above can be obtained.

A third embodiment of the present invention will be described with reference to FIG. Here, of the P region on the side of one scanning light 14 of the two scanning lights 14 and 15 generated by one hologram (for example, hologram A) of the hologram disk 3 located at the incident position S of the incident line. The mirror 8 is provided only at the position 17a. Therefore, the mirror 8 is arranged only at the positions 17a, 18a, 19a, 20a of one of the regions sandwiching the hologram disk 3 and the positions 17b, 18b, 18b, 18b of the regions Q on the opposite side are arranged.
By not providing the mirror 8 on 19b and 20b, it becomes possible to use only one of the two scanning lines constantly generated by one hologram for reading and scanning. The same effect as in the case of the first embodiment can be obtained.

[0022]

The invention according to claim 1 is a laser light source,
A shaping optical system for beam shaping the light emitted from the laser light source, a hologram disk for scanning the beam shaped laser light, and a mirror optical system for reflecting, separating and condensing the scanned scanning light, In an optical scanning device provided with a photodetector for irradiating the barcode with the scanning light and detecting the reflected light, the scanning light diffracted and scanned on the opposite side to the incident direction of the laser light on the hologram disk. A hologram having different spatial frequencies with different diffraction angles is formed, and a mirror is arranged at a position corresponding to the diffraction angle by one of the holograms having different spatial frequencies, and the other hologram. Since the mirror is arranged at the position corresponding to the diffraction angle by, each hologram has different spatial frequency and corresponds to the different diffraction angle. Since the mirrors are arranged at different positions, two scanning lines will not be generated at the same time, and the reading signal will not be dulled or a noisy signal will not be generated. Multi-directional scanning light can always be drawn stably, which enables accurate reading.

According to a second aspect of the present invention, a laser light source, a shaping optical system for beam-shaping the light emitted from the laser light source, a hologram disk for scanning the beam-shaped laser light, and the scanned light are used. In a light scanning device equipped with a mirror optical system that reflects, separates, and condenses scanning light, and a photodetector that irradiates the scanning light on a barcode and detects the reflected light, One of two scanning lights generated by one hologram is formed by forming a hologram having different spatial frequencies so that the diffraction angles of the scanning light diffracted and scanned on the opposite side to the incident direction are different from each other. The scanning angles of the mirrors at the positions for reflecting the two scanning lights are mutually changed so that the scanning lights of the two scanning lights are used for the signal reading and the other scanning light is not used for the signal reading. Having provided, by disposing the mirror at different angles corresponding to the diffraction angle in this way, in which it is possible to obtain the same effect as the first aspect of the present invention.

According to a third aspect of the present invention, a laser light source, a shaping optical system for beam-shaping the light emitted from the laser light source, a hologram disk for scanning the beam-shaped laser light, and the scanning are performed. In a light scanning device equipped with a mirror optical system that reflects, separates, and condenses scanning light, and a photodetector that irradiates the scanning light on a barcode and detects the reflected light, One of two scanning lights generated by one hologram is formed by forming a hologram having different spatial frequencies so that the diffraction angles of the scanning light diffracted and scanned on the opposite side to the incident direction are different from each other. Since the mirror is arranged only on the scanning light side, one of the scanning lights having different diffraction angles obtained by passing through the holograms having different spatial frequencies in this way. The same as the invention according to claim 1, wherein only one of the two symmetrical scanning lines generated by vertically arranging the mirror on the side of the scanning light of the above is used for scanning. It is possible to obtain various effects.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing a state where a position of a mirror is shifted according to a first embodiment of the present invention.

FIG. 2 is a front view showing a state of a hologram disc.

FIG. 3 is a configuration diagram showing a state in which the angle of the mirror according to the second embodiment of the present invention is shifted.

FIG. 4 is a configuration diagram showing a third embodiment of the present invention.

FIG. 5 is an optical path diagram showing a problem of a conventional scanner.

FIG. 6 is a configuration diagram showing a first conventional example.

FIG. 7 is a waveform diagram showing a signal waveform of a scanning line detected by a photodetector.

[Explanation of symbols]

 1 laser light source 2 shaping optical system 3 hologram disc 4 mirror optical system 5 photodetectors 8a, 8b mirror A hologram B hologram

Claims (1)

Claim: What is claimed is: 1. A laser light source, a shaping optical system for beam-shaping the light emitted from the laser light source, a hologram disc for scanning the beam-shaped laser light, and the scanned optical system. In a light scanning device equipped with a mirror optical system that reflects, separates, and condenses scanning light, and a photodetector that irradiates the scanning light on a barcode and detects the reflected light, A hologram having different spatial frequencies is formed so that the diffraction angles of the scanning light diffracted and scanned on the opposite side to the incident direction are different, and the diffraction angle by one of the holograms having different spatial frequencies The optical scanning device is characterized in that the mirror is arranged at a position corresponding to the position and the mirror is arranged at a position corresponding to the diffraction angle of the other hologram. . 2. A laser light source, a shaping optical system for beam-shaping the light emitted from the laser light source, a hologram disk for scanning the beam-shaped laser light, and reflection and separation of the scanned scanning light. In a light scanning device equipped with a mirror optical system for condensing and a photodetector for irradiating the barcode with scanning light thereof and detecting reflected light thereof, the direction of incidence of laser light on the hologram disk is opposite. A hologram having different spatial frequencies is formed such that the diffraction angles of the scanning light diffracted to the side and scanning are different from each other, and one of the two scanning lights generated by the one hologram reads a signal. In order to prevent the other scanning light used for the above from being used for signal reading, the mirrors at the positions for reflecting the two scanning lights are arranged so as to be different from each other. Optical scanning device. 3. A laser light source, a shaping optical system for beam-shaping the light emitted from the laser light source, a hologram disk for scanning the beam-shaped laser light, and reflection / separation of the scanned scanning light. In a light scanning device equipped with a mirror optical system for condensing and a photodetector for irradiating the barcode with scanning light thereof and detecting reflected light thereof, the direction of incidence of laser light on the hologram disk is opposite. A hologram having different spatial frequencies is formed so that the diffraction angles of the scanning light diffracted and scanned to one side are different, and only one scanning light side of the two scanning lights generated by the one hologram is formed. An optical scanning device having a mirror.