JPH0534615A - Laser bar-code scanner - Google Patents

Abstract

PURPOSE:To offer the laser bar-code scanner which can execute a signal processing of a bar-code by using an amplifier whose band is not so wide and whose cost is low, and also, is inexpensive and compact. CONSTITUTION:In the laser bar-code scanner in which an emitted light from a laser light source 9 is subjected to beam shaping by a beam shaping optical system, its shaped beam is scanned by a rotatable optical scanning machine 11, its scanning light is reflected by plural pieces of mirrors 12 provided in the periphery and plural pieces of scanning lines 13 for intersecting to each other are dram, and by scanning its scanning line 13 on the bar-code surface and detecting its reflected light by a photodetector, read of information of a bar-code is executed, such a large scanning angle limit lens 14 as all the scanning lines 13 for crossing each other are allowed to pass through is provided on an optical path before the scanning line 13 obtained by a fact that the emitted light is scanned by the optical scanning machine 11 and reflected by the mirror 12 is emitted from an emitting window.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION This invention relates to laser bar code scanners.

[0002]

2. Description of the Related Art A conventional laser bar code scanner is disclosed in, for example, Japanese Patent Laid-Open No. 61-25119. This is provided with a laser beam scanning mechanism for deflecting and scanning a laser beam emitted from a laser light source, and a fixed hologram for deflecting a laser beam deflected and scanned by the laser beam scanning mechanism again is used. It is characterized in that it is arranged on the optical path. FIG. 8 shows a configuration including a hologram disc 1 as a fixed hologram. In this case, the scanning light 2 of the parallel laser beam is applied to the rotating hologram disk 1 to be deflected. The deflected beam remains parallel light and moves in the direction of arrow A as the hologram disk 1 rotates. The scanned parallel light is focused on the hologram window 3 and is scanned on a bar code surface (not shown). Then, the reflected light 4 in the opposite direction to the scanning light travels in the opposite direction as shown by the broken line. After passing through the hologram disc 1 again, it is detected by a photodetector (not shown), and the information of the bar code can be read.

In FIG. 8, the hologram disk 1 has a converging function in order to converge a scanned parallel beam. Therefore, the beam scanned at a large scanning angle has an apparently small scanning angle (approximately 0 ° in the figure). In this way the hologram disc 1
Has a function of reducing the apparent scanning angle.

Further, as another apparatus, there is one using an fθ lens in order to ensure the uniform speed of the scanning line of the laser printer. In this case, as a result, the beam scanned at a large scanning angle has an apparently small scanning angle.

[0005]

Generally, there are various methods for reading a bar code label. That is, there are a method of reading with scanning lines that cross each other, which is often used in stores, and a method of reading with scanning lines that are parallel to each other, which is often seen in factories and warehouses. Further, in order to improve the readability, the reading depth is increased. FIG. 6 shows the reading depth. The deeper the reading depth of the scanning light 6 scanned by the optical scanner 5, that is, the distance m from the scanning surface.
At a position B that is 2 m deeper than the position A, the speed 2v of the scanning line at the position B farther from the bar code reader is faster than the speed v of the scanning line at the closer position A. It will increase in proportion to the distance from.

In other words, since the width of the vertical stripe of the bar code does not change, from the viewpoint of signal processing, an amplifier for processing bar code information at a farther position B as shown in FIG. 7 (a). It means that the frequency 7 of the amplifier needs to be high, and the frequency 8 of the amplifier which processes the barcode information in the closer position as shown in FIG. 7B needs to be lower. That is, this indicates that it is necessary to use the amplifier frequency in a wider band. However, such high performance small size,
In reality, developing low-cost amplifiers has become extremely difficult, and cross-scanning has become the mainstream of laser bar code scanners used for POS in recent years. The current situation is that it has not sufficiently dealt with such problems.

[0007]

According to a first aspect of the present invention, light emitted from a laser light source is shaped by a beam shaping optical system, and the shaped beam is scanned by a rotatable optical scanner. Then, the scanning light is reflected by a plurality of mirrors arranged around it to draw a plurality of scanning lines intersecting each other, the scanning lines are scanned on the barcode surface, and the reflected light is detected by light. In a laser bar code scanner for reading information of the bar code by detecting with a scanning device, a scanning line obtained by scanning the emitted light by the optical scanning device and reflecting by the mirror is emitted from an emitting window. A scanning angle limiting lens large enough to pass all the scanning lines crossing each other was arranged on the previous optical path.

According to a second aspect of the invention, in the first aspect of the invention, the scanning angle limiting lens is a hologram lens or a distributed index lens.

According to the third aspect of the invention, the light emitted from the laser light source is shaped by the beam shaping optical system, and the shaped beam is scanned by the rotatable optical scanner.
The scanning light is reflected by a plurality of mirrors arranged around it to draw a plurality of scanning lines that intersect with each other, the scanning lines are scanned on the bar code surface, and the reflected light is detected by a photodetector. In a laser bar code scanner for reading the information of the bar code by detecting, the emitted light is scanned by the optical scanner and the scanning line obtained by being reflected by the mirror is emitted from the emission window. A reflecting mirror having a curved reflecting surface is arranged on a separate optical path of each scanning line.

[0010]

According to the first aspect of the invention, the apparent scanning angle can be made small by using a single scanning angle limiting lens for a large number of scanning lines in multiple directions at one time. Thus, it is possible to prevent the scanning width from changing so much depending on the depth.

According to the second aspect of the invention, since the scanning angle limiting lens is a hologram lens or a distributed index lens, it can be made thinner than the configuration according to the first aspect.

According to the third aspect of the present invention, the normal reflection is performed by reflecting the scanning line by a reflecting mirror having a curved reflecting surface on each optical path before the scanning line is emitted from the emission window. Since the function of the mirror and the function of reducing the apparent scanning angle can be obtained at the same time, and the lens in the vicinity of the exit window can be omitted, the structure can be made thinner than the invention according to claim 2.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. FIG. 1 shows the overall configuration of this apparatus. That is, the emitted light from the laser light source 9 is beam-shaped by a beam-shaping optical system (not shown), and the shaped beam is scanned by the hologram disk 11 as an optical scanning device that can rotate via the mirror 10. To be done. In addition, the hologram disk 11 is a motor 11
It can be rotated by a. Then, the scanning light obtained by the scanning is reflected by a plurality of mirrors 12 arranged around the scanning light and travels upward to draw a plurality of scanning lines 13 intersecting each other, and the scanning is performed. The present invention relates to a laser bar code scanner for reading information of the bar code by scanning the line 13 on the bar code surface (not shown) and detecting reflected light from the bar code surface by a photo detector (not shown). is there.

Here, the scanning line 13 obtained by scanning the emitted light by the hologram disk 11 and reflecting it by the mirror 12 is on the optical path in the vicinity of the emission window before being emitted from the emission window (not shown). In addition, a single lens 14 as a scanning angle limiting lens that is large enough to pass all the scanning lines that cross each other is disposed. The shape of the lens 14 is formed as a thick convex lens having a semicylindrical shape.

In such a structure, the lens 14 has the function of reducing the apparent scanning angle θ'of light incident at a certain scanning angle θ, as shown in FIG. In addition, each scanning line 13 striking the lens 14
Since the beam is a light which converges gently or a light which diverges, it is made to converge on the reading area by the lens 14. By disposing one large lens 14 in the vicinity of the exit window in this way, each scanning line has a small apparent scanning angle θ ′ at a time, so that the scanning width does not change so much even if the depth becomes deep. I will be done. Therefore, it is possible to prevent the signal frequency of the bar code from changing much depending on the depth, so there is no need to use the frequency of the amplifier in a wide band, and the size is small and the band is not very wide.
It becomes possible to perform bar code signal processing with a low-cost amplifier, which makes it possible to obtain an inexpensive and compact laser bar code scanner.

Next, a second embodiment of the present invention will be described with reference to FIG. Here, instead of using the convex lens 14 as described above as the scanning angle limiting lens, a flat plate-shaped distributed index lens 15 (or hologram lens) having a condensing function due to the distribution of the refractive index is provided. It was done. By providing such a flat lens having no wall thickness, the scanner can be made even thinner.

Next, a third embodiment of the present invention will be described with reference to FIG. Here, as the scanning angle limiting lens, a concave mirror 16 as a reflecting mirror having a curved reflecting surface is used. In this case, the concave mirror 16 is arranged on each optical path of each scanning line 13 before the scanning line 13 obtained by being reflected by the mirror 12 is emitted from the emission window. Further, the reflecting mirror having the curved reflecting surface is not limited to the concave mirror 16, and a parabolic mirror or a cylindrical mirror may be used.

However, when a rotating mirror is used in the optical scanning device, the rotating mirror has a curvature.
When a hologram scanner is used as the optical scanning device, the hologram is provided with the aberration opposite to that of the concave mirror 16 or the parabolic mirror. Specifically, as shown in FIG. 5, the surface of the hologram 19 is exposed with the reference light 17 having the same wavelength as the reproduction wavelength by using the concave mirror 16 (or parabolic mirror) used on the object light 18 side. As a result, the grating is formed so as to have an aberration opposite to that of the concave mirror 16.

As described above, by reflecting the scanning line by the concave mirror 16 (parabolic mirror or cylindrical mirror), it is possible to simultaneously obtain the function of the normal reflecting mirror and the function of reducing the apparent scanning angle. Is possible,
Further, this makes it possible to omit the lens near the exit window, and thus to obtain a much thinner scanner.

[0020]

According to the first aspect of the invention, the light emitted from the laser light source is shaped by the beam shaping optical system, and the shaped beam is scanned by the rotatable optical scanner.
The scanning light is reflected by a plurality of mirrors arranged around it to draw a plurality of scanning lines that intersect with each other, the scanning lines are scanned on the bar code surface, and the reflected light is detected by a photodetector. In a laser bar code scanner for reading the information of the bar code by detecting, the emitted light is scanned by the optical scanner and the scanning line obtained by being reflected by the mirror is emitted from the emission window. Since a scanning angle limiting lens that is large enough to pass all the scanning lines that cross each other is arranged on the optical path, a large number of scanning lines in multiple directions can be used to scan an apparent scanning angle with one scanning angle limiting lens at a time. It is possible to make it small, and this makes it possible to make the scanning width not much different from the depth depending on the depth with a simple structure and at a low cost. Since it performs signal processing by a small amplifier in valence, in which it is possible to provide a compact scanner inexpensive.

According to the second aspect of the invention, since the scanning angle limiting lens is a hologram lens or a distributed index lens, it can be made thinner than the configuration of the first aspect.

According to a third aspect of the present invention, the light emitted from the laser light source is shaped by a beam shaping optical system, the shaped beam is scanned by a rotatable optical scanner, and the scanning light is scanned. By drawing a plurality of scanning lines that intersect with each other by being reflected by a plurality of mirrors arranged around it, scan the scanning lines on the barcode surface, and detect the reflected light with a photodetector In a laser bar code scanner for reading the information of the bar code, each scanning line before the emission line is scanned by the optical scanning device and reflected by the mirror to obtain a scanning line. Since a reflecting mirror having a curved reflecting surface is provided on each of the separate optical paths, the reflecting line reflects the scanning line, and the normal reflecting mirror functions and the apparent scanning angle. Together becomes effects can be reduced and can be obtained at the same time, in which even more may be thinner than the arrangement of the invention described in claim 2 can be omitted in the vicinity of the lens of the exit window.

[Brief description of drawings]

FIG. 1 is a side view showing an overall configuration of a laser barcode scanner that is a first embodiment of the present invention.

FIG. 2 is a schematic diagram showing a relationship between a certain scanning angle incident on a lens and its apparent scanning angle.

FIG. 3 is a side view showing a second embodiment of the present invention.

FIG. 4 is a side view showing a third embodiment of the present invention.

FIG. 5 is an explanatory diagram showing a method of forming a grating in which a hologram has an aberration opposite to that of a concave mirror.

FIG. 6 is a schematic diagram showing the relationship between reading depth and scanning line speed.

FIG. 7A is a waveform diagram showing a state when the amplifier frequency is high, and FIG. 7B is a waveform diagram showing a state when the amplifier frequency is low.

FIG. 8 is a schematic diagram showing a state of a scanning principle of a scanning line which is a conventional example.

[Explanation of symbols]

9 Laser light source 11 Optical scanner 12 mirror 13 scan lines 14 Scanning angle limiting lens 15 distributed index lens 16 Reflector

Claims (3)

[Claims] 1. A light beam emitted from a laser light source is shaped by a beam shaping optical system, the shaped beam is scanned by a rotatable optical scanner, and the scanning light is disposed around the beam. By drawing a plurality of scanning lines which are reflected by a plurality of mirrors and intersect each other, the scanning lines are scanned on the bar code surface, and the reflected light is detected by a photodetector so that the information of the bar code is In a laser bar code scanner for reading, the scanning lines crossing each other on the optical path before the scanning lines obtained by scanning the emitted light by the optical scanning device and reflecting by the mirror are emitted from the emission window. A laser bar code scanner characterized in that a scanning angle limiting lens that is large enough to pass all of the above is provided. 2. The laser barcode scanner according to claim 1, wherein the scanning angle limiting lens is a hologram lens or a distributed index lens. 3. A light beam emitted from a laser light source is shaped by a beam shaping optical system, the shaped beam is scanned by a rotatable optical scanner, and the scanning light is arranged around it. By drawing a plurality of scanning lines which are reflected by a plurality of mirrors and intersect each other, the scanning lines are scanned on the bar code surface, and the reflected light is detected by a photodetector so that the information of the bar code is In a laser bar code scanner for reading, scanning lines obtained by scanning the emitted light by the optical scanning device and reflected by the mirrors are on separate optical paths of the respective scanning lines before being emitted from an emission window. A laser bar code scanner characterized in that a reflecting mirror having a curved reflecting surface is provided in the laser bar code scanner.