JP2758447B2 - Laser barcode scanner using hologram - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a laser barcode scanner using a hologram disc.

2. Description of the Related Art Examples of a conventional laser barcode scanner will be sequentially described below.

First, as a first conventional example, as disclosed in Japanese Patent Application Laid-Open No. Sho 60-254112, a hologram disk
The layers have a layer structure, and the layers have diffraction directions in opposite directions. At least one of the layers is formed to be axially symmetric with respect to the rotation axis. in this case,
The focus position on the scanning plane is prevented from being shifted due to wavelength fluctuation of the light source or the like.

As a second conventional example, as disclosed in Japanese Patent Application Laid-Open No. 63-218914, at least two band-shaped holograms which intersect each other are formed on a reading window, The light beam is deflected by passing through the optical disk and becomes scanning light for the medium to be read, thereby making it possible to reduce the size of the apparatus.

As a third conventional example, as disclosed in Japanese Patent Application Laid-Open No. 63-156293, a laser beam scanning apparatus for forming a scanning pattern composed of a plurality of scanning lines having different scanning directions corresponds to a scanning line. A mirror group consisting of a plurality of mirrors provided as described above and a single bottom common mirror for further reflecting the reflected light from the mirror group and directly emitting the light to the outside, thereby making the entire apparatus compact. Is being planned.

As a fourth conventional example, a hologram provided on a rotating disk is irradiated with a light beam to draw a scanning line, and the same hologram using the reflected light for scanning and irradiating an object surface to be read, or the same. A condensing hologram having a focal point at the same position as the hologram is used, and a signal is detected to read information.

Problems to be Solved by the Invention In the case of the first conventional example, two diffraction gratings are provided, and one of the diffraction gratings causes discontinuous movement of the light beam in the scanning line direction due to wavelength fluctuation, and the other diffraction grating. Move the discontinuous motion in the opposite direction to cancel, thereby reducing the discontinuous motion of the light beam due to wavelength fluctuation.

However, this method cannot prevent discontinuous movement in the scanning line direction (called the main scanning direction) unless a light beam is vertically incident when the scanning width is not zero. In addition, it is possible to prevent movement in the direction perpendicular to the scanning line (called the sub-scanning direction). However, when this device is applied to a bar code reader, discontinuous movement in the scanning line direction causes a reading error. Cause.

In the case of the second conventional example, it is possible to draw a cross scan line and reduce the size of the apparatus by placing a strip hologram crossing on the reading window. However, in this case, the scan lines crossing at different angles are used. When the number of the holograms is large, the holograms have to be stacked thicker by that much, which requires a high level of technology for the production, and also has the disadvantage that the light use efficiency is reduced.

In the case of the third conventional example, a mirror group for forming a scanning line is provided,
After that, the entire device can be made compact by reflecting the light of the mirror group directly to the outside by the common mirror. However, in such a structure, the direction of the light is adjusted by the optical system up to the common mirror. It is necessary to change it to some extent, and there is a design limitation that it must be arranged immediately before direct emission of light to the outside or immediately before a fixed hologram plate to be synthesized, and the degree of freedom in design is narrow.

In the case of the fourth conventional example, if the light beam is incident on the hologram disk perpendicularly or at a black angle, the reflected light and the primary light of the reflection may be incident on the light receiving element. The angle of incidence must be tilted from normal incidence or the black angle. But if you do this,
Aberrations are easily generated, and the shape of the light beam is easily deformed.
For this reason, a special exposure method for correcting this is required, and the influence of wavelength fluctuation also occurs.

Means for Solving the Problems According to the first aspect of the present invention, light emitted from a laser light source is guided to a hologram disk, and a bar code surface is scanned by light from the hologram disk, and the light is reflected from the bar code surface. In a laser barcode scanner for detecting light by a light receiving element and reading information on the barcode surface, a vertical incidence means for vertically emitting light emitted from the laser light source on a rotation axis of the hologram disk is provided. Was.

According to the second aspect of the present invention, the light emitted from the laser light source is guided to the horom ram disk, the bar code surface is scanned by the light from the hologram disk, and the reflected light from the bar code is detected by the light receiving element. A laser barcode scanner for reading information on the barcode surface, wherein the hologram disk is of a linearly spaced grid, and vertical incidence means for vertically emitting light emitted from the laser light source to the hologram disk. Was provided.

According to the third aspect of the present invention, the light emitted from the laser light source is guided to the horom ram disk, the bar code surface is scanned by the light from the hologram disk, and the reflected light from the bar code is detected by the light receiving element. In the laser barcode scanner for reading information on the barcode surface, a vertical incident means for vertically incident light emitted from the laser light source on the hologram disk is provided, and the perpendicular incident means A mirror that reflects vertically diffracted light is provided,
The light reflected by the mirror in the plane having the same rotation axis as the hologram disk and returned to the vicinity of the hologram disk again is deflected again by the optical member rotating integrally with the hologram disk, and the barcode surface is deflected. It was made to scan.

According to the first aspect of the present invention, a light beam is perpendicularly incident on the rotation axis of the hologram disc by the perpendicular incidence means, so that the light beam is always diffracted in the direction of the grating vector of the grating formed on the hologram disc. Therefore, even if there is a wavelength variation in the main scanning direction, no spot is emitted in the scanning direction, so that the wavelength variation is not affected and the beam position does not fluctuate.

According to the second aspect of the present invention, the light beam is vertically incident on the hologram disk of the equally-spaced vertical linear lattice by the vertical incidence means, so that the light beam always moves in the direction of the grating vector of the grating formed on the hologram disk. Since the light is diffracted, the spot does not fly in the scanning direction even if there is an apex variation in the main scanning direction, so that it is not affected by the wavelength variation, and the beam position does not fluctuate.

According to the third aspect of the present invention, the beam which is changed in the grating vector direction of the grating by the perpendicular incidence means is reflected by the mirror, and the reflected light is returned to the vicinity of the hologram disk again to be incident on the optical member. In addition, the scanning angle of the scanning line can be further increased, and the size of the apparatus can be reduced.

Embodiment A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows a vertical incidence means 3 for vertically incident a light beam emitted from a semiconductor laser 1 as a laser light source on a hologram disc 2.
In this case, the vertical incidence means 3 is composed of a collimator lens 4 and a reflection mirror 5. Reference numeral 10 denotes a scanning line.

In such a configuration, a light beam emitted from the semiconductor laser 1 is collimated by a collimating lens 4 and then reflected by a reflection mirror 5 to form a hologram 6 (hereinafter referred to as a grating) formed on the surface of the hologram disk 2. ). At this time, the vertically incident light beam always diffracts in the direction of the grating vector V of the grating 6 as shown in FIGS. 2 (a) and (b) to FIGS. 4 (a) and (b). is there. The effect that the incident light beam always diffracts in the direction of the grating vector V does not cause a position error of the light beam due to a wavelength change in the main scanning direction, so that no reading error occurs. Suitable for reading vertically long lines like a code reader. In this case, a circular beam is made incident on the grating 6 so that the light beam has the same depth and beam diameter in all directions of deflection.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 (a) and (b) to FIG. The present embodiment shows an example for enlarging the scanning angle of a scanning line.

That is, the vertical incidence means 3 and the hologram disk 2
In addition to using the mirror 7 for reflecting the light diffracted by the hologram disk 2, as shown in FIG. 5 (b), a grating 13 as an optical member for enlarging the scanning width of the scanning line is the same as the hologram disk 2. It was formed in a plane having a rotation axis, here, on the surface of the hologram disc 2.

The reason why the scanning angle can be increased will be described with reference to FIG. Now, assuming that light goes around in a two-dimensional plane, if the hologram disk 2 is rotated by θ,
The light reflected by the mirror 7 also returns with an inclination of θ with respect to the reference line l. And the light is hologram disk 2
The light is incident on the grating 6 formed on the surface at an incident angle of 2θ and is deflected at 3θ with respect to the reference line l. Actually, since scanning is not performed in such a two-dimensional plane, 3
θ, but generally the rotation angle of the hologram disc 2 can be scanned at a large angle, thereby increasing the scan angle of the scan line.
The optical diameter on the way can be reduced.

As an optical member, in addition to the above-described grating 6, a rotating mirror 14 having the same rotation axis as the hologram disk 2 on the rotation axis and having the same rotation speed as the hologram disk 2 as shown in FIG. Alternatively, as shown in FIG. 8, a curved rotating mirror 15 and a lens 16 can be used in combination. in this case,
By providing the curved mirror 15 and the grating 6 formed on the hologram disk 2 with a light collecting function, it is not necessary to lengthen the optical path of light received by a light receiving element (not shown). The size can be reduced, and the light receiving efficiency for preventing a decrease in the SN of the detected signal can be further increased.

As a mirror that reflects the diffracted light to generate the scanning light, a mirror 7 composed of a plurality of mirrors as shown in FIG.
Alternatively, a mirror 17 as shown in FIGS. 7 and 8 can be used.

According to the first aspect of the present invention, light emitted from a laser light source is guided to a hologram disk, a bar code surface is scanned by light from the hologram disk, and reflected light from the bar code surface is received by a light receiving element. In the laser barcode scanner which reads the information on the barcode surface by detecting the light from the laser light source, a vertical incident means for vertically incident light emitted from the laser light source on a rotation axis of the hologram disk is provided. When the light beam is perpendicularly incident on the rotation axis of the hologram disk by the incident means, the light beam is always diffracted in the direction of the grating vector of the grating formed on the hologram disk. Even if there is fluctuation, the spot does not fly in the scanning direction, so it may be affected by wavelength fluctuation. Therefore, there is an effect that the beam position does not fluctuate.

According to a second aspect of the present invention, light emitted from a laser light source is guided to a horom ram disk, a bar code surface is scanned with light from the hologram disk, and reflected light from the bar code surface is detected by a light receiving element. A laser barcode scanner for reading information on the barcode surface, wherein the hologram disk is of a linearly spaced grid, and vertical incidence means for vertically emitting light emitted from the laser light source to the hologram disk. Since the light beam is vertically incident on the hologram disk of the equally-spaced vertical linear lattice by the vertical incidence means, the light beam is always diffracted in the direction of the grating vector of the grating formed on the hologram disk. Therefore, even if there is a wavelength fluctuation in the main scanning direction, a spot is formed in the scanning direction. Without being affected by the wavelength fluctuation because there field, not cause variations in the beam position.

According to the third aspect of the present invention, the light emitted from the laser light source is guided to the horom ram disk, the bar code surface is scanned by the light from the hologram disk, and the reflected light from the bar code is detected by the light receiving element. In the laser barcode scanner for reading information on the barcode surface, a vertical incident means for vertically incident light emitted from the laser light source on the hologram disk is provided, and the perpendicular incident means A mirror that reflects vertically diffracted light is provided,
The light reflected by the mirror in the plane having the same rotation axis as the hologram disk and returned to the vicinity of the hologram disk again is deflected again by the optical member rotating integrally with the hologram disk, and the barcode surface is deflected. Since scanning is performed, the light beam deflected in the direction of the grating vector of the grating by the vertical incidence means is reflected by a mirror, and the light reflected and returned to the vicinity of the hologram disk is again incident on the optical member, thereby performing scanning. The scanning angle of the line can be further expanded,
In addition, there is an effect that the device can be made compact.

[Brief description of the drawings]

FIG. 1 is a perspective view showing a state of a vertical incidence means according to a first embodiment of the present invention, and FIGS. 2 to 4 show incident light in a direction of a lattice vector when the light is vertically incident. FIG. 5 (a) is a side view showing a second embodiment of the present invention, FIG. 5 (b) is a plan view of the hologram disk, and FIG. 6 is scanning of a scanning line. FIGS. 7 and 8 are explanatory diagrams for explaining the principle of enlargement of the corner, and FIG.
It is a side view which shows the modification of. DESCRIPTION OF SYMBOLS 1 ... Laser beam, 2 ... Hologram disk, 3 ... Vertical incidence means, 7 ... Mirror, 13, 14, 15 ... Optical member, 17 ... Mirror

Claims (3)

(57) [Claims] 1. A light beam emitted from a laser light source is guided to a hologram disk, a bar code surface is scanned by light from the hologram disk, and light reflected from the bar code surface is detected by a light receiving element to detect the bar light. In a laser barcode scanner for reading information on a code surface, a hologram ram is provided, which is provided with vertical incidence means for vertically irradiating light emitted from the laser light source on a rotation axis of the hologram disc. Laser barcode scanner. 2. A light emitted from a laser light source is guided to a hologram disk, a bar code surface is scanned by light from the hologram disk, and reflected light from the bar code surface is detected by a light receiving element to detect the bar code. In a laser barcode scanner for reading information on a code surface, the hologram disk has a linear lattice of equal intervals, and vertical incidence means for vertically emitting light emitted from the laser light source to the hologram disk is provided. A laser barcode scanner using a hologram characterized by the following. 3. A light emitted from a laser light source is guided to a hologram disk, a bar code surface is scanned by the light from the hologram disk, and light reflected from the bar code surface is detected by a light receiving element, and the bar code is detected. In a laser barcode scanner for reading information on a code surface, a perpendicular incidence means for vertically emitting light emitted from the laser light source to the hologram disc is provided, and the light is vertically incident on the hologram disc by the perpendicular incidence means. A mirror for reflecting the diffracted light, wherein the light reflected by the mirror and returned to the vicinity of the hologram disk in a plane having the same rotation axis as the hologram disk is integrated with the hologram disk and rotates. The bar code is scanned again by being deflected by a member. Laser bar code scanner using a hologram to.