JPH0696258A - Light beam scanner - Google Patents

Abstract

PURPOSE:To execute a light beam scan in many directions with a compact shape. CONSTITUTION:The scanner is provided with a hologram plate 1 for scanning an incident light beam L1, and a prism 2 having the refracting surface 2b for allowing a part of a scanning light beam L2 outputted from the hologram plate 1 to be made incident, refracting and outputting it, and the reflecting surface 2d for allowing another part of the scanning light to be made incident, reflecting it internally and allowing it to be made incident on the refracting surface 2b at a different incident angle. The scanning light beam 12 which is made incident directly on the refracting surface 2b of the prism 2 and refracted becomes a light beam L4 scanned in one direction, is reflected internally by the reflecting surface 2d, made incident on the refracting surface 2b at a different incident angle and the refracted scanning light beam becomes the light beam L4 scanned in the other direction. Since the light beam L4 scanned in plural directions is generated by using the same refracting surface 2b of the prism, the light beam scan in many directions can be executed by a compact shape.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light beam scanning device, and more particularly to a light beam scanning device suitable for use in a bar code reader.

[0002]

2. Description of the Related Art Bar code readers are being widely used as point-of-sales (POS) input terminals or device terminals for factory automation (FA) product management automation.

A bar code reader scans a bar code attached to a product located at a relatively distant position with laser light,
There is one that receives reflected light from a bar code with a sensor and reads it, and a light beam scanning device is used for such a bar code reader.

The light beam scanning device for laser light is a scanning light which is diffracted by a rotating hologram plate to change its direction gradually, and the scanning light is made incident on a scan pattern forming mechanism composed of a plurality of mirrors. It is general that the contents of the barcode can be read regardless of the orientation of the barcode by scanning in multiple directions.

[0005]

However, in the above-mentioned conventional scanning device, in order to increase the scanning direction of the light beam, it is necessary to additionally install a mirror, which makes it difficult to dispose the mirror and the scanning device of the scanning device. There was a problem that it was unavoidable to increase the size.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object of the present invention is to provide a light beam scanning device capable of scanning a light beam in multiple directions with a compact shape without using a mirror.

[0007]

To explain the structure of the present invention, a light beam scanning device includes a hologram plate 1 having a moving diffraction surface 1a for scanning an incident light beam L1 and an output from the hologram plate 1. Of the scanning light beam L2, at least one refracting surface 2b for injecting, refracting and outputting a light beam within a predetermined scanning region, and at least one refraction surface for injecting and internally reflecting another light beam within a predetermined scanning region. The surface 2b is provided with a prism 2 having at least one reflecting surface 2d which makes the light beam in the predetermined scanning area incident at a different incident angle or at a different incident position.

[0008]

In the above structure, a part of the scanning light beam L2 is directly incident on the refracting surface 2b of the prism 2 and is refracted to become a light beam L4 which is scanned in one direction.
Further, another part of the scanning light beam L2 is internally reflected by the reflecting surface 2d of the prism 2 and is incident on the refracting surface 2b at a different incident angle and is refracted to be a light beam L4 which is scanned in the other direction. Become.

However, since the light beam L4 which is scanned in a plurality of directions is formed by using the same refracting surface 2b of the prism, the light beam scanning in a plurality of directions can be performed in a compact shape without providing a large number of mirrors. You can

[0010]

Embodiment 1 FIG. 1 shows the appearance of a bar code reader in which the light beam scanning device of the present invention is installed.
1 is provided with a substantially rectangular reader body 4 (FIG. 2) with the rear lower surface supported. The lower half of the front part of the reader body 4 is a recess, and a prism 2 is provided. From this prism 2, a laser light beam L4 is emitted toward a base 3 below,
The base 3 is scanned in multiple directions (five in four directions in this embodiment). When the article 5 with the bar code 51 is placed on the base 3, the light beam L4 passes over the bar code 51 and is reflected as a signal light of strong and weak in accordance with the change of the reflectance of the bar code 51, and then again. The light is input to the light receiving sensor in the device via the prism 2.

When the bar code on the light receiving sensor is identified by the built-in decoder, the reading indicator lamp 41 provided on the front upper surface of the reader body 4 is turned on. Since the light beam L4 is scanned in multiple directions, signal light corresponding to the barcode 51 can be obtained even if the posture of the article 5 on the base 3 changes.
It does not become unreadable.

A schematic structure inside the reader body 4 is shown in FIG.
A circular hologram plate 1 is provided above the prism 2 in the vicinity of the horizontal top surface 2e.
It is fixedly supported by the output shaft of and is rotating. A large number of concentric diffraction fringes decentered from the center are formed on the diffraction surface 1a (lower surface in the figure) of the hologram plate 42, and as shown in FIG.
The light beam L1 incident on the center of the plate is rotated on the hologram plate 1 so that the hologram plate 1 is formed on the conical surface having the incident point as the apex.
While being swirled and scanned in the same direction as the arrow (indicated by an arrow in the figure), the hologram plate 1 focuses the light on one point.

As shown in FIG. 5, the prism 2 is a vertical back surface 2d which is orthogonal to the top surface 2e and functions as a reflection surface for internal light.
And a front surface 2a inclined downward and left and right side surfaces 2b, 2
It is composed of c.

In FIG. 3, a laser projector 44 for emitting a light beam L1 is provided in the rear portion of the reader body 4,
Between the laser projector 44 and the rear surface 2d of the prism 2,
A condenser lens 43 and a mirror 45 are provided, and the light beam L1 from the laser projector 44 is condensed by the condenser lens 43 and the mirror 4.
After passing through the hole formed in 5, the light enters the back surface 2d of the prism 2. The mirror 45 reflects the convergent light (broken line in the figure) from the condenser lens 43 upward and makes it incident on the light receiving sensor 46 provided near the top surface of the reader body 4. The output of the light receiving sensor 46 is amplified by the amplifier 47, and the built-in decoder 4
Sent to 8.

A procedure for scanning the light beam in the above structure will be described below. In FIG. 6, the laser projector 4
The light beam L1 emitted horizontally from 4 is the rear surface 2 of the prism 2.
The light enters straight from d and reaches the front surface 2a, where it is totally reflected and enters the center of the hologram plate 1 above. The incident light beam L1 is diffracted obliquely downward by the hologram plate 1,
With the rotation, the scanning light beam L2 turns as described above. The scanning light beam L2 is incident on the top surface 2e of the prism and refracted downward.

While the scanning light beam L2 is within a predetermined swirl region, the scanning light beam L2 is refracted at the top surface 2d and then R
As shown by the loci of 1, R2 and R3, the side surface 2 of the prism 2
It is incident on b, the front surface 2a, and the side surface 2c to be refracted. Then, the refracted light beam L4 is projected onto the base 3 as the scanning line S1 while moving on the locus R1 and is moved on the scanning line S while moving on the loci R2 and R3.
2, S3 is projected onto the base 3. Thus, the scanning lines S1, S2, which are three lines in two directions substantially orthogonal to each other, are formed on the base 3.
S3 is obtained.

When the scanning light beam L2 reaches the turning region, it is refracted at the top surface 2e and then totally reflected at the back surface 2d as shown in FIG. 7, and the reflected light L3 becomes the scanning light beam L2. Is incident on each side surface 2b, 2c of the prism 2 and is refracted at different angles and positions as shown by the loci of R4 and R5. The refracted light beam L4 has the locus R
While moving 4 and R5, they are projected onto the base 3 as scanning lines S4 and S5 which intersect each other.

In this way, as shown in FIG. 8, the loci R1, R2, R3, R4, R are made for each revolution of the hologram plate 1.
The light beam L4 is projected from each point on 5 to the base 3, and as a whole, 5 scanning lines are obtained in 4 directions.

A signal light corresponding to a change in the reflectance is reflected and transmitted from the bar code scanned by the light beam L4, and a signal light (broken line in FIG. 3) returning from the same direction as the light beam projection direction is generated. , The front surface 2a of the prism 2 or each side surface 2b, 2
The light is refracted at c, enters the hologram plate 1 through the top surface 2e, is diffracted, and changes its direction vertically downward. Then, the light enters the front surface 2 a from the inside, is totally reflected in the horizontal direction, and reaches the condenser lens 43. After passing through the condenser lens 43, as described above, the light is reflected by the mirror 45 and input to the light receiving element 46.

In this way, it is possible to obtain scanning lines of four directions and five lines by using a compact prism having five surfaces of the top surface 2e, the back surface 2d, the front surface 2a, and the both side surfaces 2b and 2c. Compared to using a plurality of mirrors, the barcode reader main body can be downsized.

An example of the dimensions of each part of the prism used in this embodiment is shown in FIGS. 9 (a) and 9 (b) (in the figure, the unit is
mm).

In this embodiment, since the front surface 2a of the prism 2 is used as a reflecting surface for making the light beam L1 emitted from the laser projector 44 incident on the hologram plate 1, the structure can be further simplified and compact. .

[0023]

Second Embodiment Although a reflection type hologram plate is used in the above embodiment, a transmission type hologram plate is used instead of the reflection type hologram plate, and a laser projector 44 is provided above the hologram plate 1 as shown in FIG. Alternatively, even if the light beam L1 is directly incident on the plate surface of the hologram plate 1, the scanning light beam L2 similar to that in the above-described embodiment can be obtained.

In each of the above-mentioned embodiments, the shape of the prism is not limited to the above, and a plurality of reflecting surfaces are formed, or the reflecting surface also serves as a refracting surface, and further, a shape of reflecting a plurality of times inside the prism. Can also be

Further, the hologram plate may be divided into a plurality of regions so that the diffraction angles and the focal lengths are made different.

[0026]

As described above, the light beam scanning device of the present invention has a compact shape and can perform light beam scanning in multiple directions, and can be suitably used for bar code readers and the like.

[Brief description of drawings]

FIG. 1 is an overall perspective view of a bar code reader including a light beam scanning device of the present invention.

FIG. 2 is a perspective view of the main body of the barcode reader.

FIG. 3 is a schematic structural diagram of the inside of the main body of the barcode reader.

FIG. 4 is a perspective view of a hologram plate.

FIG. 5 is a perspective view of a prism.

FIG. 6 is an optical path diagram of a light beam scanning device.

FIG. 7 is an optical path diagram of a light beam scanning device.

FIG. 8 is an optical path diagram of a light beam scanning device.

FIG. 9 is a side view and a front view of a prism.

FIG. 10 is an optical path diagram of a light beam scanning device according to another embodiment of the present invention.

[Explanation of symbols]

 1 Hologram plate 1a Diffraction surface 2 Prisms 2a, 2b, 2c Refraction surface 2d Reflection surface

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsuro Ishizuka 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Japan Auto Parts Research Institute (72) Inventor Ikuyasu Kato 14 Iwatani, Shimohakaku-cho, Nishio-shi, Aichi Stock Japan Auto Parts Research Institute, Inc. (72) Inventor Yasuhiko Koike 1-1-1, Showa-cho, Kariya city, Aichi prefecture Nihon Denso Co., Ltd.

Claims (1)

[Claims] 1. A hologram plate having a moving diffractive surface for scanning an incident light beam, and among the scanning light beams output from the hologram plate, a light beam within a predetermined scanning area is incident, refracted and output. At least one refracting surface, and at least one of the other light beams in the predetermined scanning area are incident and internally reflected to be incident on the at least one refracting surface at an incident angle or an incident position different from that of the light beam in the predetermined scanning area. A light beam scanning device comprising: a prism having a reflecting surface.