JPH0793454A - Bar code reader - Google Patents

Abstract

PURPOSE:To obtain a compact and inexpensive bar code reader with simple, constitution by providing a transparent lens obtained by integrating a flood lens and a light receiving lens into one body and an optical scanning part scanning a bar code by vibrating by driven by an electromagnetic driving means. CONSTITUTION:In an optical reading part 20, the flood lens body 51 converging light beams from a laser diode 4 as a light source and the light receiving lens part 52 condensing reflected light 7 from the bar code 8 are integrated to be the transparent lens 50 consisting of transparent resin or glass. The planar reflection mirror of the optical scanning part 70 vibrates by driven by the electromagnetic driving means 60 impressing signals of different phases to two coils and when the light beams from the laser diode 4 is converged by the transparent lens 50 and guided to the planar reflection mirror, reflected light 6 from the planar reflection mirror vibrates to right and left to scan the bar code 8. Reflected light 7 from the bar code 8 is condensed by the transparent lens 50 and guided to a light receiving unit 10 to be photoelectric-converted.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reader for optically scanning a bar code which is printed digital information to read bar code information. This type of bar code reader optically reads a bar code attached to a product or the like in order to manage the product or the like, and is installed in a production line of a factory or a checkout place of a supermarket. In general, a barcode reader scans a barcode surface with an optical means (for example, a laser light source and a rotating polygon mirror), photoelectrically converts an intensity signal of light reflected from the barcode by a light receiver (for example, a photodiode), The output is waveform-shaped and converted into a binary pulse train, and then a combination of pulse widths is identified and output as an encoded data train to the outside.

[0002]

2. Description of the Related Art FIG. 5 is a schematic view of a bar code reader showing a conventional device of this type. In the figure, 8 is a bar code, 13 is a motor 1, a rotary polygon mirror that is rotated in a predetermined direction by the motor 1, a laser diode 4 as a light source 4, a light projecting lens 5, a light receiving lens 9, a light receiver 10 and an amplifier 11. An optical reading unit including a waveform shaper 12 and the like, and a decoder 14 that decodes bar code information based on a signal from the optical reading unit 13. Further, 6 is a scanning beam, 7 is reflected light, and 15 is a reading result.

In this bar code reader, a laser beam emitted from a laser diode 4 is focused by a light projecting lens 5, and the laser beam is reflected by an optical scanning section 3 composed of a rotary polygon mirror 2 rotated by a motor 1. As a scanning beam 6, the barcode 8 is scanned. The reflected light of the laser light obtained by hitting the barcode 8 is guided to the light receiver 10 through the light receiving lens 9 and photoelectrically converted by the light receiver 10. The electric analog signal photoelectrically converted by the light receiver 10 is amplified to a constant voltage by the amplifier 11, and then shaped into a binarized signal by the waveform shaper 12 and output to the decoder 14. The decoder 14 analyzes the combination of the pulse widths of the binarized pulse signal, converts the combination into encoded data according to a prescribed format, and outputs the read result 15 to the outside.

[0004]

The optical scanning unit 3 for scanning the light beam 6 on the surface of the bar code 8, which is one component of the optical reading unit 13 in the conventional bar code reader shown in FIG. The rotating polygon mirror 2 is a polygonal prism having a prismatic structure having a plurality of reflecting planes in the circumferential direction, and the motor 1 is a columnar structure having a rotor and a stator. A volume space that combines the cylindrical structure of the motor is required. Also, the polygon mirror cannot be used as a reflecting surface because it hangs near the sides and between the upper and lower ends between adjacent reflecting surfaces of the polygon mirror, and the polygon mirror cannot be used as a reflecting surface due to the dripping caused by mechanical cutting. The unusable area (ineffective area) must be secured in the width and height directions of each reflecting surface as an addition of the size of the light beam of the light source, and the volume increases as the number of surfaces increases. Have. Further, since the optical path of the light beam scanning the barcode from the light source by the optical scanning unit and the optical path of the reflected light reflected from the barcode and guided to the light receiver are largely different, the installation location of the light source and the light receiver is limited. This creates a wasted space and increases the overall size of the device, and the optical path of the light beam from the light source to the bar code and the optical path of the reflected light from the bar code are significantly different, so the light projecting lens and the light receiving lens are separated. However, since a fixture for fixing each lens is required, the number of parts is increased and the cost becomes high.

Therefore, an object of the present invention is to eliminate the above-mentioned drawbacks of the conventional device and to provide a small-sized and inexpensive bar code reader having a simple structure.

[0006]

In order to achieve the above object, the present invention is a bar code reader for optically scanning a bar code to read bar code information. The bar code reader collects a light source and a light beam from the light source. A transparent lens body that integrates a lens function for emitting light and a lens function for condensing reflected light from a barcode, an optical scanning unit including a plate-shaped reflective mirror made of a magnetic material and a torsional oscillator having a pair of spring parts. An electromagnetic driving unit that has two coils installed at both ends of the torsional vibrator of the optical scanning unit with a space therebetween, and applies signals having different phases to the two coils; And a light receiver for converting the reflected light from the generated barcode into an electric signal.

[0007]

In the present invention constructed as described above, the plate-shaped reflecting mirror of the optical scanning section is driven by the electromagnetic driving means for applying signals having different phases to the two coils and is vibrating. When the light beam is converged by the transparent lens body and guided to the plate-shaped reflection mirror, the reflected light from the plate-shaped reflection mirror sways to the left and right to scan the barcode. The reflected light from the bar code is condensed by the transparent lens body, guided to the light receiver, and photoelectrically converted.

[0008]

FIG. 1 is a schematic configuration diagram of a bar code reader showing an embodiment of the present invention. The same parts as those of the conventional device shown in FIG. Figure 1
5 is different from the conventional device shown in FIG. 5 in that the laser diode 4 as a light source is used in the optical reading section 20.
A transparent resin (for example, polycarbonate or PMMA) in which a light projecting lens unit 51 having a lens function of converging a light beam from the lens and a light receiving lens unit 52 having a lens function of condensing the reflected light 7 from the barcode 8 are integrated. Etc.) or a transparent lens body 50 made of glass, and an optical scanning unit 70 that is driven by an electromagnetic driving unit 60 and reciprocally vibrates.

The structures of the electromagnetic driving means 60 and the optical scanning section 70 are shown in FIG. In FIG. 2, 71 is the optical scanning unit 70.
Which is a torsion oscillator that constitutes a first reflection coil and is composed of a plate-shaped reflection mirror 72 made of a magnetic material and a pair of first torsion springs 73.
The torsion oscillator 74, the outer frame portion 75 made of a magnetic material, the second torsion oscillator 77 including the pair of second torsion springs 76, and the pair of end portions 78. The surface of the plate-shaped reflection mirror 72 of the first torsion oscillator 74 is formed as a mirror surface by aluminum vapor deposition means or the like. The plate-shaped reflection mirror 72 and the outer frame portion 75 can reciprocally vibrate about the first and second torsion springs 73 and 76, respectively. The torsional vibrator 71 has a pair of end portions 7 attached to both leg pieces 81 and 82 of a substrate 80 having a U-shaped cross section.
8 and 78 are firmly fixed to each other by a pressing member 79 so as to be fixed. The electromagnetic drive means 60 includes a torsion oscillator 71.
Of a pair of yokes 61 and 62 fixed to the bottom of the substrate 80 and coils 63 and 64 wound around the pair of yokes 61 and 62. Is configured so that an electric signal is applied to each of them separately. As the coils 63 and 64, other than the coils wound around the yokes 61 and 62, those formed in a sheet shape can be used.

Next, the operations of the electromagnetic driving means 60 and the optical scanning section 70 shown in FIG. 2 will be described. Electromagnetic driving means 6
When an electric current is passed through the coil 63 (or 64) of 0, magnetic flux is generated, and a force for attracting the outer frame portion 75 of the magnetic body arranged near the yoke 61 (or 62) is generated. Therefore, by applying electric signals having different phases to the two coils 63 and 64, respectively, the first and second oscillators 74 and 77 are
The plate-shaped reflection mirror 72 and the outer frame portion 75 reciprocally oscillate about the first and second torsion springs 73 and 76 as rotation centers. When the light beam from the laser diode 4 is guided to the plate-like reflection mirror 72 that reciprocally oscillates in this manner, the light beam 6 as the reflected light sways to the left and right. The angle at which the light beam 6 swings to the left and right is twice the angle at which the plate-shaped reflecting mirror 72 swings. In this way, by applying electric signals having different phases to the two coils 63, 64, the light beam from the laser diode 4 is guided and reflected by the plate-like reflection mirror 72 that reciprocally oscillates, thereby causing light to be reflected on the bar code surface. To scan.

In this embodiment, the two coils 6
I explained that the winding directions of 3, 64 are the same,
It is also possible to use two coils 63 and 64 having different winding directions. In this case, by applying an in-phase electric signal from the electromagnetic driving means 60 to the two coils 63 and 64, the plate-shaped reflection mirror 72 is reciprocated. Optical scanning can be performed by vibrating.

Since the amplitude of the torsional oscillator 71 changes in proportion to the magnetic attraction force or the electrostatic attraction force which is a driving source, a large attraction force is required to obtain a wide optical scanning width, and a large driving power is required. Is required. Therefore, in this embodiment, the resonance frequencies of the first and second oscillators 71 and 77 are different from each other, and the resonance frequency of the first torsion oscillator 71 is higher than that of the second torsion oscillator 77. The outer frame portion 75 of the second vibrator 77 is configured to be set by the electromagnetic drive means 60 by the electromagnetic drive means 60.
When driven at the resonance frequency of 7, the amplitude of the outer frame portion 75 of the second vibrator 77 is small, and the amplitude of the plate-shaped reflecting mirror 72 of the first vibrator 71 is large, so that the plate-shaped mirror 72 can be driven with a small driving power. A wide optical scanning width can be obtained by increasing the amplitude of the reflection mirror 72 (such a torsional oscillator is filed by the applicant as Japanese Patent Application No. 4-291839).

FIGS. 3 and 4 are perspective views showing different embodiments of the transparent lens body having a lens function of condensing the light beam from the laser diode 4 and the reflected light from the bar code 8, respectively. FIG. 3 shows a transparent lens body 50a having a light projecting lens portion 51a and a light receiving lens portion 52b formed by forming two convex portions having a predetermined curvature on a transparent resin (polycarbonate, PMMA, etc.) or glass. The light projecting lens 51a of the transparent lens body 50a sets the curvature at which the light beam converges at Q with the refractive index n of the material being constant according to the distance to the light emitting point P of the laser diode 4 and the point Q corresponding to the bar code surface. It can be obtained by selecting and forming a hemispherical surface which is selected and has a curvature and projects only in the emission direction of the light beam of the transparent lens body 50a. Also, the light receiving lens 5
2a is also the same method as the light projecting lens 51a, and the generation point Q1 of the reflected light from the barcode surface and the light receiving point R of the light receiver 10
By selecting the curvature at which the reflected light converges at R with the bending ratio n of the material being constant according to the distance to, and forming a hemispherical surface protruding only in the incident direction of the reflected light of the transparent lens body 50a with that curvature. can get.

4 is different from the embodiment of FIG. 3 in that the light projecting lens portion 51b and the light receiving lens portion 52b of the transparent lens body 50b are formed by a diffraction grating. The light projecting lens portion 51b and the light receiving lens portion 52b of the transparent lens body 50b have their respective curvatures selected as described with reference to FIG.
(Dense).

[0015]

As described above, according to the present invention,
By configuring the optical scanning unit with a torsional oscillator having a plate-shaped reflection mirror, the optical scanning unit can have a planar structure,
In addition, it is possible to optically scan a wide range of the barcode surface by reciprocally vibrating the plate-shaped reflecting mirror and increasing the amplitude interval, and the optical path of the light beam from the optical scanning unit and the reflection from the barcode. Since the optical path of the light can be brought close to each other, it becomes possible to integrate two lenses, which collect the light beam from the light source and the reflected light from the barcode, into one transparent lens body. Since the whole can be miniaturized and the two lenses are integrated into one transparent lens body, the number of parts can be reduced, so that an inexpensive bar code reader can be provided.

[Brief description of drawings]

FIG. 1 is a schematic configuration diagram of a bar code reader showing an embodiment of the present invention.

FIG. 2 is a perspective view showing a configuration of an electromagnetic driving unit and an optical scanning unit of FIG.

FIG. 3 is a perspective view showing an embodiment of the transparent lens body of FIG.

FIG. 4 is a perspective view showing an embodiment of a transparent lens body different from that in FIG.

FIG. 5 is a schematic configuration diagram showing a conventional barcode reader.

[Explanation of symbols]

 4 light source (laser diode) 8 bar code 10 light receiver 20 optical reading unit 50 transparent lens body 51 light emitting lens unit 52 light receiving lens unit 60 electromagnetic drive means 63 coil 64 coil 70 light scanning unit 71 torsional oscillator 72 plate reflection Mirror 74 First torsion oscillator 75 Outer frame 77 Second torsion oscillator

Claims (6)

[Claims] 1. A bar code reader which optically scans a bar code to read bar code information, and a light source, a lens function of condensing a light beam from the light source, and a reflected light from the bar code. A transparent lens body having an integrated lens function, an optical scanning unit composed of a plate-shaped reflecting mirror made of a magnetic material and a torsional oscillator having a pair of springs, and an interval between both ends of the torsional oscillator of the optical scanning unit. Electromagnetic driving means for applying signals having different phases to the two coils and light receiving for converting the reflected light from the bar code condensed by the transparent lens body into an electric signal A bar code reader characterized by being equipped with a container. 2. The optical scanning unit according to claim 1, wherein the optical scanning unit includes a first oscillator having a plate-shaped reflecting mirror and a pair of springs, and a pair of springs of the first oscillator. A second vibrator connected to the outer frame part and a pair of spring parts made of a magnetic material; and two coils arranged at both ends of the second vibrator with a space between them. A barcode reader comprising an electromagnetic drive circuit for applying signals having different phases to two coils. 3. The optical scanning unit according to claim 1, wherein the optical scanning unit includes a first oscillator having a plate-shaped reflecting mirror and a pair of springs, and a pair of springs of the first oscillator. A second vibrator which is connected and has an outer frame part made of a magnetic material and a pair of spring parts; and two coils which are installed at both ends of the second vibrator and are spaced apart from each other and have different winding directions. ,
A bar code reader comprising an electromagnetic drive circuit for applying in-phase signals to the two coils. 4. The method according to claim 1 or 2, wherein
The bar code reader is characterized in that each of the two coils has a sheet shape. 5. The method according to claim 1 or 2, wherein
A bar code reader characterized in that the two lenses of the transparent lens body are spherical surfaces having different curvatures. 6. The method according to claim 1 or 2, wherein
A bar code reader characterized in that the two lenses of the transparent lens body are made of diffraction gratings having different shapes and periods.