JPS6145216A - Laser scanner - Google Patents

Abstract

PURPOSE:To obtain a small-sized, high-reliability, and inexpensive laser scanner by providing a rotating member with a single slanting surface containing one point on the axis of rotation of the rotating member, and forming a hologram on the slanting surface part. CONSTITUTION:Laser light 23 is converted into a plane wave 25, which is reflected by a small mirror 24, then enters the rotating member 20 through the hole in the center of a holed Fresnel lens 29, and the light is diffracted and polarized by a hologram 28 which is the slanting surface of the rotating member 20 to obtain scanning light 25, which is converged to illuminate a bar code 26. Signal scattered light 27 reflected by the bar code 26 returns to the hologram 28 and is converted into a plane wave parallel to the axial line of rotation of the rotating member 20; and the light is converged through the lens 29 provided to one end of the rotating member 20 to focus an image on a photodetector 30 arranged on the rotary axial line of the rotating member 20. Thus, the hologram is provided on the single slanting surface of the rotating member to reduce the size and cost and obtain high reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a laser scanner that scans with laser light and focuses signal scattering light from an object to be read using a hologram. In order to save labor, barcode reading devices have come into use that scan the barcode TA printed on the exterior of a product and input it into a computer.

BACKGROUND ART FIG. 4 is a diagram for explaining the basic configuration of a barcode reading device. In the figure, 1 is an outer casing, 2 is a He-Ne laser as a light source, 3 is a beam expander, and 4 is a A hologram disk having a plurality of holograms, 5 a drive motor thereof, 6 an upper window opened in the operation surface of the housing, 7
is the scanning light, 8 is the signal light, 9 is the ninth perforated mirror that separates the scanning light and the signal light, 2-1lO is the condenser lens, 11 is the photodetector, 12 is the bar code printed on the exterior of the product. are shown respectively. The operation of this device is such that the source passing through the perforated mirror 9 is converged and deflected by the hologram disk 4 to scan the barcode 12 on the product.

The signal light 8 modulated by the barcode 12 is converged again by the hologram disk 4, reflected by the perforated mirror 9, passed through the lens 10, and detected by the photodetector 11. A conventional laser scanner consists of an optical scanning section consisting of a hologram disk and a motor, an input optical system consisting of a laser tube or laser diode, a beam expander, etc.
A recombination system consisting of a perforated mirror, a lens, a filter, and a photodetector, a scanning pattern synthesis mirror system consisting of a group of multiple mirrors, a mirror connecting these components, and a t-1 Because it is assembled inside the housing, these structures are I7J? The parts must be arranged with a precision of 1, and since there are a large number of parts, very high assembly precision is required for each part. Therefore, it is not easy to assemble,
Another drawback is that adjustments are required after assembly. The hologram disk of the Mayumoto scanning unit is a round disk in which light cannot be processed internally, and the optical path area is shared between the optical scanning unit, the incident light such as a perforated mirror, and the re-imaging light separation element. In addition to the above, each group is separate9 and the density is low spatially, making the skin scanning/focusing system more compact, integrating these into a module, and ultimately making the scanner more compact. The drawback was that it was difficult to reduce the price.

To solve the above-mentioned problems, the present invention provides a laser scanner that scans a laser beam and focuses signal scattered light from an object to be read on a hologram. A sloped portion meeting at a point on the line is formed, and the hologram is disposed on the sloped portion.

In the laser scanner, the hologram itself may be used to diffract and scan the laser beam onto the object to be read, but advantageously, a reflecting mirror is provided on the axis of rotation of the inclined surface of the rotating member. By disposing a reflection hologram and making the laser beam incident on the reflection mirror or the reflection hologram from the direction of the axis of rotation, the object to be measured can be scanned with the laser beam.

In order to solve the above-mentioned problems, the present inventors
We have already disclosed a technique for modularizing laser beam scanning and focusing, and forming an inclined surface on a rotating member and arranging a hologram on the inclined surface in order to reduce the size (Japanese Patent Application No. 1983-1999).
No. 224325, etc.).

However, all of the specific examples of the rotating member of this laser scanner have a plurality of hologram-casting slope parts. Each of the plurality of holograms must have a sufficient size to ensure a specific amount of light beam, and the radial direction of the rotating member is still large. Therefore, in the present invention, the dimension in the radial direction is minimized by making the hologram-arranging slope part only a single plane (AA7 asset) that extends at one point on the rotational axis of the rotating member.

Furthermore, in conventional laser scanners (including the above-mentioned laser scanner that we disclosed earlier), the incident beam to the hologram (or mirror) and the signal condensed light occupy the same optical path area, so that the incident light and the condensed light are The light beams have to be separated using a perforated mirror, a perforated lens, a small mirror, etc., which imposes constraints on the optical system configuration and prevents the miniaturization of laser scanners.

In contrast, in a preferred embodiment of the laser scanner of the present invention, a reflecting mirror is provided on the rotational axis of the single slope portion of the rotating member, and the laser beam is directed onto this reflecting mirror from the side opposite to the signal convergence source side of the hologram. Since the laser beam is incident and the reflected light is used for scanning, there is no restriction on the structure of the optical system as mentioned above.

Example Embodiments of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a diagram illustrating a first embodiment of a laser scanner according to the present invention. In the figure, 20 is a rotating member, 21 is a stator, 22 is a bearing, (barcode), 2
7 is a signal scattered light, 28 is a hologram, 29 is a perforated Fresnel lens, and 30 is a semiconductor photodetector.

In this embodiment, a rotating member 20 having a T-shape obtained by cutting a cylinder diagonally
A hologram 28 is disposed on the elliptical cutting slope. This rotating member 20 is supported by bearings 22 to form nine rotors, and together with the stator 21, constitutes a motor. Therefore, the 0He-Ne laser or semiconductor laser (
The laser beam emitted from the collimator (not shown)
The C laser beam 23) is converted into a plane wave 25 by a small mirror 24, and then enters the rotating member 20 through the hole in the center of the perforated Fresnel lens 29, forming an inclined surface of the rotating member 20. It is diffracted and deflected by the hologram 28 (
Scanning light 25), barcode printed on the exterior of the product 26
A focused beam of light is irradiated on top. The signal scattered light 27 reflected from the barcode 26 returns to the hologram 28, where it is converted into a plane wave parallel to the rotation axis of the rotating member 200, and is converted into a plane wave parallel to the rotation axis of the rotating member 200.
Member 2゜0-qIC provided hole, Vne ApL/
The light is focused on the 7th lens 29 and formed into an image on a semiconductor photodetector 30 disposed on the rotational axis of the rotating member 20 .

In this way, in this embodiment, the incident optical system, the scanning section, and the reimaging optical system are highly integrated using rotating members and are modularized. Since this rotating member has a single facet hologram and no idle 71 sets, compared to the conventional multiple facet (segment) type,
Since the light condensing area per seven assets is the same, the dimension in the radial direction is minimized. The dimension in the radial direction is theoretically about 1/1 (approximately 5/7) of that of a hologram consisting of two 7-assets.

A hologram can be created by interfering a spherical wave from an obliquely downward direction with a plane wave from a direction parallel to the axis of rotation on an emulsion attached to the inclined surface of the rotating member 20. FIG. 7 is an m-th diagram illustrating a second embodiment of the invention. In the figure, the same parts as in the first embodiment are designated by the same reference numerals.

In this embodiment, there is a reflection fi at the center of the hologram 40 on the single slope portion of the rotating member 20, that is, at the portion that intersects with the axis of rotation.
41'i. The reflecting mirror can be arranged by depositing silver or aluminum on the center of the hologram, or by pasting a twisted mirror. Then, a reflecting mirror 41 is inserted from the outside of the rotating member 20 along the rotational axis.
The reflected light 251: the object to be read (
(barcode) 26. barcode 26
Similarly to the first embodiment, the second scattered signal light 27 reflected by
The hologram 40 converts the wave into a plane wave parallel to the rotational axis of the rotating member 20 , converges it with a 7-Renel lens 43 at the other end of the rotating member 20 , and forms an image on the semiconductor photodetector 30 .

The optical system of this second embodiment is similar to the first embodiment,
The laser beam can be scanned by rotating the rotating member 200 times. The reason why this scanning is possible is that if the laser beams ft and 42t are incident on the reflecting mirror 41 along the axis of rotation of the rotating member 200,
This is because the scanning of the reflected light of the reflecting mirror 41 and the scanning of the hologram 40 as the member rotates 200 times can be drawn as the same scanning locus.

In this embodiment, as is clear from FIG.
1'fI: In use, the optical path region of the incident light 420 is automatically separated from the optical path region of the signal condensed light 440. As a result, the perforated Lennel lens 29, the small mirror 24, the holder for the small mirror 29, and the other hand Rk for separating the incident light and the signal light, which are required in the SGL embodiment, can be omitted.

Since there are no small mirrors, etc., it is possible to place a photodetector very close to the 7-lens lens and form an image on it. In this way, the laser scanner of this embodiment has a simplified configuration, a reduced number of parts, a smaller size, and more modularization.

For example, a plane mirror may be used as the reflector 41 to reflect the convergent laser beam, and a concave mirror or a parabolic mirror may be used to converge parallel light to add a converging effect to the convergent light. Even if a reflection hologram is used instead, the size of the zero reflection@41 is usually 3 to 4 fiφ since the necessary beam diameter at the starting point of the scanning beam is usually about 1 to 2 mφ, and in this case, the rotating member 20 is Fig. 3 is a diagram illustrating a third embodiment of the present invention. In the figure, the same parts as in the first and second embodiments are denoted by the same reference numerals 7C.

In this embodiment, like the second embodiment, the hologram 50
A reflecting mirror 41 is arranged at the center of the hologram to separate the optical path region of the incident light 42 from the optical path region of the signal condensed light 51. As a result of this separation of the optical path regions, the signal condensed light by the hologram is once parallelized. Since there is no need to convert the signal light 27 into light and then converge it with a 7-lens lens, the signal light 27 can be converted into a hologram 5.
0 directly onto the photodetector 30. The round hologram 50 for this purpose is called a self-focusing hologram, which combines a diverging spherical wave from diagonally below the slope of the rotating member and a convergent spherical wave forming an image on the photodetector from below in the direction of the rotation axis. It can be created by interference on an emulsion. tz, a window may simply be provided on the upper surface of the rotating member 20, and a 7-Renel lens is not required.

In this way, this embodiment has a simpler configuration, a reduced number of parts, a smaller size, and a higher module ratio than the second embodiment.

Effects of the Invention As is clear from the above explanation, according to the present invention, by disposing a hologram on a single slope of the rotating member, the relationship between laser beam scanning and focusing can be modulated into a more sophisticated configuration. , which enables smaller size, higher reliability, and lower cost.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a main part for explaining a first embodiment of a laser scanner according to the present invention, and FIG. 2 is a sectional view of a main part for explaining a second embodiment of a laser scanner according to the present invention. FIG. 3 is a ninth sectional view of a main part of a laser scanner according to a third embodiment of the present invention, and FIG. 4 is a schematic diagram of a basic configuration of a conventional bar code reading device. Engineering...outer casing, 2...laser, 3...
... Beam expander, 4 ... Hologram disk, 5 ... Drive motor, 7 ...
Scanning light, 8...Signal light, 9...Perforated mirror, 10...Condensing lens, 11...
Photodetector, 12...Barcode, 20...
...Rotating member, 21...Stator, 22...
...bearing, 23...incident light, 24...
・Small mirror, 25...Scanning light, 26...Bar code, 27...Signal scattered light, 28...Hologram, 29...Perforated flap. Renel lens, 3
0...Photodetector, 40...Hologram, 41...Reflector, 42...Incoming light,
43. Old... Fresnel lens, 44... Signal condensed light, 5o... Hologram, 51...
Signal focusing light.

Claims (1)

[Claims] 1. In a laser scanner that scans a laser beam and focuses signal scattered light from an object to be read using a hologram, a rotating member includes a single point on the axis of rotation of the rotating member. 1. A laser scanner characterized in that a slope is formed and the hologram is disposed on the slope. 2. The laser scanner according to claim 1, wherein the hologram itself is used to diffract and scan laser light onto the object to be read. 3. A reflecting mirror or a reflection hologram is disposed on the rotation axis of the inclined surface of the rotating member, and a laser beam is incident on the reflection mirror or reflection hologram from the direction of the rotation axis. A laser scanner according to claim 1, which scans a measurement object with a laser beam.