JPH0682175B2 - Hologram scan - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Outline] In a hologram scanner in which an electromagnetic motor and at least one of a laser light source and a photodetector are housed in a hollow top, a magnetic field generated by the motor affects the laser light source and the photodetector. By eliminating this, the hologram scanner is stabilized.

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a hologram scanner that uses a hologram to perform optical scanning.

2. Description of the Related Art In order to save labor in register operations in supermarkets and the like, a bar code reading device that reads a bar code printed on the exterior of a product and inputs it into a computer is used.

Holographic scanners utilizing holograms are suitable for the optical scanning section of such bar code readers and are widely used. As a powerful means for downsizing such a hologram scanner, a holotop scanner using a hologram rotating body (holotop) has appeared, and a scanner in which an outer rotor type motor is housed in the holotop, that is, the applicant of the present invention A hologram scanner (Japanese Patent Application No. Sho 59-265193) filed on March 18, was invented.

[Conventional technology]

FIG. 2 is a cross-sectional view showing a main part of a hologram scanner according to the prior art. The hologram scanner has a hollow top in which a motor, a laser light source, a photodetector and an A / D converter are housed.

In FIG. 2, 1 is a frame, 2 is an axis, 3 is a lead wire, 4 is a rotor, 5 is a hollow top (hologram rotating body), 6 is a bearing, 7 is a stator, 8 is a reflection type Fresnel lens, and 9 is a laser. Beam exit hole, 10 is laser beam,
11 is a laser light source, 12 and 13 are holograms, 14 is a convex lens, 1
Reference numeral 5 is a photodetector, 16 is a scanning light, 17 is a signal light, and 18 is an A / D converter.

A hollow shaft 2 for fixing the laser light source 11, the lead wire 3 of the stator 7, etc., is fixed to the frame 1, and a hollow top 5 having a rotor 4 on the shaft 2 is rotatably mounted via a bearing 6. A stator 7 and a reflection type Fresnel lens 8 are attached to the shaft 2, a laser light source 11 for emitting a laser beam 10 through a laser beam emission hole 9 opened in the reflection type Fresnel lens 8 is provided, and a hollow top 5 rotated by a rotor 4 is Holograms 12, 13 and convex lens 14 on the bottom slope
And a photodetector 15 is further provided at the lower end of the shaft 2.

The hologram scanner configured as described above is provided with the rotor 4
And the stator 7 constitute a motor, and the hollow top 5 can be rotated. Then, the laser beam 10 from the laser light source 11 is diffracted by the holograms 12 and 13 to become scanning light 16.

In addition, the scattered signal light 17 from the barcode is the hologram 1
The light is diffracted by 2, 13 into parallel light, which is further focused on the photodetector 15 by the reflective Fresnel lens 8 and the convex lens 14, and the photodetector 15 converts the optical signal into an analog electric signal,
The analog electric signal is converted into a digital electric signal by the A / D converter 18, and the barcode can be read.

[Problems to be solved by the invention]

In the conventional hologram scanner shown in FIG. 2, when a predetermined current is passed through the stator 7 to rotate the hollow top 5, a vertical magnetic field 19 as shown in FIG. Affected by laser light source
The emission intensity of 11 may fluctuate, or an erroneous signal may be sent from the photodetector 15 and the A / D converter 18.

Further, since the hollow top 5 is fitted and supported on the shaft 2 at one place via the bearing 6, the rotation of the hollow top 5 becomes unstable and rotational runout easily occurs.

The problem due to the magnetic field can be solved by providing the stator 7 with the laser light source 11, the photodetector 15 and the A / D converter 18 sufficiently separated, but such a method can reduce the size of the hologram scanner. Will be greatly impaired.

[Means for solving problems]

FIG. 1 is a sectional view showing a main part of a hologram scanner according to an embodiment of the present invention.

In FIG. 1 in which the same reference numerals are used for the same parts as in FIG. 2, 21 is a shield plate, 22 is a bearing interposed between the shaft 2 and the shield plate 21, and 25 is a hollow top.

The hologram scanner of the present invention which solves the above problems,
As shown in FIG. 1, a light source 11 for the laser light 10, a photodetector 15, and an electromagnetic motor for rotating the rotating body 25 are housed inside a hollow rotating body (holotop) 25, and are attached to the rotating body 25 or The formed holograms 12 and 13 diffract the laser light 10 that irradiates the holograms 12 and 13 from the inside of the rotating body 25 and emits the laser light 10 to the outside of the rotating body 25, and the emitted light 16 also forms
The rotation of 25 serves as scanning light for the object to be read, and the signal scattered light from the object to be read by the scanning light 17
Is again focused by the holograms 12 and 13 and the photodetector 15
In the hologram scanner of the type to be guided to, the shield plate 21 that partitions the laser light source 11 and the photodetector 15 from the electromagnetic motor is provided.

[Action]

In the hologram scanner equipped with the above means, an electric field is passed through the stator 7 to generate an electromagnetic field, which is shielded by a shield plate.
Blocked by 21 laser light source 11, photodetector 15 and A / D converter 18
In addition, the hollow top 25 is supported by the shaft 2 at two points, that is, the conventional bearing 6 and the newly provided bearing 22, and rotates, so that the rotation is stable and the rotational runout is reduced.

As a result, the reliability of reading the signal light 17 was improved, and the effect of achieving further miniaturization was obtained.

〔Example〕

The embodiment will be specifically described below with reference to FIG.

In FIG. 1, a hollow top 25 is fitted on a shaft 26 through a rotatable bearing 6 and is provided with a rotor 4 and a housing 26, and holograms 12 and 13 and a convex lens 14 are provided on the bottom slope and fitted into the housing 26. The housing 27 includes a magnetic shield plate 21 which is fitted to the shaft 2 through a rotatable bearing 22 so that the magnetic shield plate 21 is integrally formed. The shield plate 21 includes the stator 7 and the laser light source 11 for A / D conversion. It is separated from the container 18.

The hologram scanner constructed in this way operates in the same manner as the hologram scanner shown in FIG.
Can rotate and read the barcode. The magnetic field (19) generated by energizing the stator 7 to rotate the hollow top 25 does not affect the laser light source 11, the A / D converter 18, and the photodetector 15 by providing the shield plate 21. At the same time, since the bearing 6 and the bearing 22 sandwiching the stator 7 rotatably support the hollow top 25, the rotation of the hollow top 25 is more stable and more accurate than the conventional structure.

In the embodiment described above, the bearing 22 may be a ball bearing or an oilless plain bearing, and when the hollow top 25 has the same rotational accuracy as the conventional hollow top 5, the bearing 22 may be replaced by a small gap. Note that it is okay to enable.

〔The invention's effect〕

As described above, according to the present invention, although a laser light source, a photodetector, etc. are housed in the hollow top together with a motor for rotation thereof, the laser light source, the photodetector, etc. are not affected by the magnetic field generated by the motor. And, the rotation accuracy is improved by supporting the hollow top on its support shaft at two separate locations.

As a result, the hologram scanner has high performance and is highly effective in improving reliability.

[Brief description of drawings]

FIG. 1 is a sectional view showing a main part of a hologram scanner according to an embodiment of the present invention, FIG. 2 is a sectional view showing a main part of a hologram scanner according to a conventional technique, and FIG. 3 is generated in a stator in a hollow top. The magnetic field that In FIG. 1, 2 is a shaft for supporting a stator of an electromagnetic motor, 4 is a rotor of the electromagnetic motor, 7 is a stator of the electromagnetic motor, 10 is laser light emitted from a laser light source, 12, 13 is a hologram, 15 is a photodetector, 16 is a holotop. The emitted laser light 17 is the signal scattered light (laser light) 21 from the object to be read, the shield plate 22 is the bearing 25, and the rotating body (holotop) is the bearing 25.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Fumio Yamagishi 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Hiroyuki Ikeda 1015, Kamedotachu, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited ( 72) Inventor Yuji Inagaki 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa Fujitsu Limited

Claims (2)

[Claims] 1. A light source (11) for a laser beam (10), a photodetector (15), and the rotating body (25) inside a hollow rotating body (25).
And an electromagnetic motor for rotating the
The hologram (12, 13) attached to or formed on the diffracted laser beam (10) that irradiates the hologram (12, 13) from the inside of the rotator (25) is diffracted to the rotator (25).
The emitted light (16) is emitted to the outside and the rotating body (2)
The rotation of (5) functions as scanning light for the object to be read, and the signal scattered light (17) from the object to be read due to the scanning light is again focused by the hologram (12, 13) and the photodetector (15 ), A shield plate (21) for partitioning the laser light source (11) and the photodetector (15) from the electromagnetic motor is provided. 2. The shield plate (21) fixed to the rotating body (25) is fitted to a shaft (2) supporting a stator (7) of the motor via a bearing (22). The hologram scanner according to claim 1, characterized in that the hologram scanner is characterized.