JPS633391A - Bar code reader - Google Patents

Abstract

PURPOSE:To expand a range that laser beams can scan by oscillating laser beams in the direction perpendicular to a scan direction by means of a bimorph reflecting laser beams when they are scanned from a polygon mirror. CONSTITUTION:A convergence lens 3 converges the laser beams 2 from a semiconductor laser 1 in a spot-like shape with a desired diameter. The optical path of the beams 2 is provided with the bimorph 4 with a reflection part. A commercial power source is added to the bimorph 4, oscillated, and deformed to reflect the beams 3. Then oscillating scan laser beams 2a' and 2a'' are formed. They are reflected on the reflection plane 5a of the polygon mirror 5, become oscillating scan laser beams 2b' and 2b'', and drawn scan loci 8' and 8'' in the direction perpendicular to the scan direction B on the scan plane 7. By adjusting the voltage of the commercial power source impressed on the bimorph 4, the scan widths of the loci 8' and 8'' can easily be modified.

Description

[Detailed Description of the Invention] [Objective of the Invention] (Industrial Application Field) The present invention scans a laser beam on a scanning surface on which a bar code is applied, and detects the bar code based on the reflected light from the scanning surface. The present invention relates to a barcode reading device for reading codes.

(Prior Art) As is well known, barcode reading devices using laser light include a fixed scanner type device described in Japanese Utility Model Application No. 58-105648, and a barcode reading device disclosed in Japanese Utility Model Application Publication No. 59-15565.
There is a wand scanner system, which is described in Publication No. 3 and the like, in which a laser pre-transmitter/receiver is held in the hand and scans a scanning surface on which a bar code is applied.

Fixed scanner type scanners are mainly used to read barcodes on items conveyed by a belt conveyor or the like. In this case, the barcode is printed directly on the object, or printed on a label or affixed to the object. Since such barcodes may have printing defects or stains, there is a risk that reading errors may occur if a single laser beam is used to scan the scanning surface on which the barcode is applied. To prevent this, the scanning range of the laser beam is widened by repeatedly moving the scanning position of the laser beam in a direction perpendicular to the scanning direction. In particular, in recent years, a wide variety of products are often transported on the same belt conveyor, and the position of the barcode varies considerably, so there is a demand for widening the scanning range of the laser beam.

Conventionally, as a method for widening the scanning range of laser light as described in 1., Document 5PIL', Vol. 84 L
aserScanning Components &
There is one described in Tea (197fi). In this device, a polygon mirror scans the laser beam, and a galvanometer mirror vibrates the laser beam in a direction perpendicular to the scanning direction.
The scanning range of the laser beam is widened.

(Problems to be Solved by the Invention) However, the conventional configuration described in 1-1 uses a galvanometer mirror, which has the disadvantage of increasing the external dimensions and increasing the cost.

Further, the control circuit for controlling the galvano mirror also has a problem in that its configuration is complicated, its external dimensions are large, and the cost 1 is also high. Furthermore, since the galvano mirror is provided near the light reception signal sensor that receives the reflected light from the scanning surface, there is a possibility that the galvano mirror may generate magnetic or electrical noise, which may adversely affect the light reception signal.

As a solution to the above-mentioned drawbacks, Japanese Patent Laid-Open No. 52-
There is one described in Publication No. 77532. In this method, the laser beam is scanned by a polygon mirror, and the laser beam is vibrated in a direction perpendicular to the scanning direction by a mirror driven by a motor and a spring, thereby widening the scanning range of the laser beam. are doing.

However, since the mirror is vibrated by a motor and a spring, there are problems in terms of durability, and it is difficult to vibrate the mirror at high frequencies. In particular, such problems become more serious in fixed scanner systems that require high-speed scanning.

- On the other hand, Japanese Patent Publication No. 59-9947 discloses that the rotation axis of a polygon mirror is tilted at a slight angle with respect to the mirror surface, and the polygon mirror scans a laser beam and vibrates the laser beam in a direction perpendicular to the scanning direction. This is shown here.

However, in this (1) configuration, since the rotation axis of the polygon mirror is tilted at a small angle with respect to the mirror surface, the Tj 8 of the co-rotating system is unbalanced or unbalanced, so it is necessary to rotate the polygon mirror at high speed. Can not.

Furthermore, since the inclination of the rotation axis of the polygon mirror is fixed, the width of the scanning range cannot be changed. Furthermore,
In order to tilt the rotation axis, high-precision machining is required, so there is also the problem of increased costs.

Further, Japanese Patent Application Laid-Open No. 59-132073 discloses a polygon mirror configured to have 1lfI degree on each surface. In this case as well, the above-mentioned
There are problems similar to those described in Japanese Patent No. 9-9947.

Therefore, the purpose of the present invention is to widen the scanning range of the laser beam, while also making it compact, eliminating the need for a complicated control circuit, and reducing costs by improving ease of installation. The present invention provides a code reading device.

[Eleventh aspect of the invention] (Means for solving the problem) The barcode reading device of the present invention has a rotatable polygon mirror that reflects laser light and scans it on a scanning surface on which a barcode is applied. At the same time, a bimorph having a reflection part that reflects the laser beam is provided in the optical path of the laser beam, and the bimorph is vibrated and deformed during scanning by the laser beam, so that the laser beam is directed perpendicular to the scanning direction on the scanning surface. Its unique feature is that it is configured to vibrate in the direction of vibration.

(Function) Along with scanning the laser beam with a polygon mirror,
Since the bimorph oscillates the laser beam in a direction perpendicular to the scanning direction, a simple 1j f using the bimorph,
The scanning range of the laser light can be widened by forming l and j;.

(Example) Hereinafter, a first example of the present invention will be described with reference to FIGS. 1 to 3.

First, in FIG. 1, 1 is, for example, a semiconductor laser, and a laser beam 2 emitted from the laser beam is focused by a focusing lens means 3 consisting of one or more lenses.
The light is focused into a spot with a desired diameter. Reference numeral 4 denotes a bimorph to be described later, which is provided on the optical path of the laser beam 2 and is adapted to reflect the laser beam 2.

Reference numeral 5 denotes a polygon mirror rotatably provided, for example, in the direction of arrow A, which reflects the reflected laser beam 2a from the bimorph 4 using a plurality of reflective surfaces 5a formed on its circumferential surface.
The scanning laser beam 2 which is the reflected light
b is scanned in the direction of arrow B on the scanning surface 7 on which the barcode 6 is applied. Note that 8 indicates the scanning locus of the scanning laser beam 2b.

Now, Bimorph 4 will be explained in detail according to FIG.

Reference numeral 9 denotes a substantially rectangular temporary spring, to which a reflecting portion, such as a reflecting mirror 10, is attached to its tip, and its base end is fastened to a base 11 by bolts or the like (not shown). 12. 12 is a piezoelectric ceramic plate, and these are attached to both sides of the above-mentioned spring 9 by means of contact. Here, the piezoelectric ceramic plate 12.12 has a commercial power source 13.
Is it a variable resistance or a voltage transformer? = The voltage is applied via the voltage adjustment means 14 made of a socket. Thereby, the bimorph 4 is deformed in the direction of arrow C or opposite to arrow C depending on the voltage applied to the piezoelectric ceramic plate 12.12.

Next, the above 1. See also Figure 3 for the effect of +Is formation!
, j as I explain. Commercial power supply 13 for Bimorph 4
, the bimorph 4 vibrates and deforms in response to the frequency of the commercial power source 13. First, when the applied voltage is zero, the bimorph 4 is not deformed as shown by the solid line. In this state, the laser beam 2 from the semiconductor laser 1 via the focusing lens means 3 is directed to the bimorph 4.
The reflected laser beam 2a is reflected by the reflecting mirror 10 as shown by the solid line, and this reflected laser beam 2a is reflected by the reflecting surface 5a of the polygon mirror 5.
The scanning laser beam 2b traces a scanning locus 8 on the scanning surface 7 as shown by a solid line.

Next, when a positive voltage is applied, the bimorph 4 deforms as shown by the dashed line. In this state, the racer beam 2 is deflected and reflected by the reflecting mirror 10 of the bimorph 4 as shown by the dashed line. As a result, the deflection reflected laser beam 2a- is reflected by the reflective surface 5a of the polygon mirror 5, and the deflection scanning laser beam 2b'' is deflected in a direction perpendicular to the scanning direction (arrow B) on the scanning surface 7, and is deflected onto the scanning surface. 7" Second, draw a scanning locus 8- shown by a dashed line (.

Furthermore, when a negative voltage is applied, the bimorph 4 deforms as shown by the broken line. In this state, racer beam 2
The reflection mirror 10 of the bimorph 4 is deflected and reflected as shown by the broken line. As a result, the deflection reflected laser beam 2
a" is reflected by the reflective surface 5a of the polygon mirror 5, and deflects in a direction perpendicular to the scanning direction of the deflection scanning laser beam 2b" or scanning surface 7", resulting in a scanning locus 8" shown by a broken line on the scanning surface 7. draw

According to this embodiment with such a configuration, the following effects can be achieved. That is, a polygon mirror 5 that reflects the laser beam 2 to scan it on the scanning surface 7 and a bimorph 4 having a reflection mirror 10 that reflects the laser beam 2 are provided, and the bimorph 4 is vibrated and deformed when the laser beam 2 is scanned. By this, laser beam 2
Since it is configured to vibrate in a direction perpendicular to the scanning direction on the scanning surface 7''2, the scanning range of the laser beam 2, that is, the scanning laser beam 2b, 2b-, 2b'' can be widened. Since the amount of deformation of the bimorph 4 is proportional to the voltage applied to the piezoelectric ceramic plate 12, the width of the scanning range (the width in the direction perpendicular to the direction of arrow B) can be easily changed by adjusting the applied voltage. , Bimorph 4 change It; Since Q can be small, there is no need to apply a resonant frequency, and the commercial power frequency can be applied to IJLI.
Since it is convenient to do so, the configuration of the voltage adjustment means 14 is
It can be converted into llt. In addition, since the bimorph 4 can be configured with a simple structure in which the piezoelectric ceramic plate 12 is attached to the plate spring 9, the productivity can be improved and the overall cost can be reduced.

FIG. 4 shows a second embodiment of the present invention, which differs from the first embodiment in that the voltage adjustment means 14 is replaced by
By providing a voltage frequency adjustment means 15 that can adjust the frequency and voltage (this is the point achieved in 1).In this second embodiment as well, it is possible to achieve the same effects as in the first embodiment. In particular, by applying a high-frequency voltage to the bimorph 4 using the voltage frequency adjustment means 15, the bimorph 4 can be vibrated and deformed at the same frequency, making it possible to cope with high-speed scanning.

In each of the above embodiments, the bimorph 4 is arranged between the semiconductor laser 1 and the polygon mirror 5, but the invention is not limited to this. For example, the bimorph 4 may be arranged between the polygon mirror 5 and the scanning surface 7. You may also set it.

[Effects of the Invention] As is clear from the above description, the present invention provides a bimorph that serves as a reflection part for reflecting the laser beam in the optical path of the laser beam, and vibrates and deforms the bimorph during scanning by the laser beam. Since the laser beam is configured to be excited in a direction perpendicular to the scanning direction on the scanning surface, the scanning range of the laser beam can be widened, and the control circuit can be made smaller and smaller. This has the excellent effect of eliminating the need for this process, improving manufacturability, and reducing costs.

[Brief explanation of drawings]

1 to 3 show a first embodiment of the present invention, FIG. 1 is a perspective view, FIG. 2 is a perspective view of the main part, and FIG. 3 is a perspective view for explaining the operation. FIG. 4 is a diagram of FIG. 2F showing a second embodiment of the present invention. In the drawings, 2 is a laser beam (laser light), 4 is a bimorph, 5 is a polygon mirror, 6 is a barboard, 7 is a scanning surface, and 10 is a reflection mirror (reflection part). Figure 1

Claims (1)

[Claims] 1. In a barcode reading device that scans a laser beam on a scanning surface on which a barcode is applied and reads the barcode based on the reflected light from the scanning surface, a barcode reader is provided that is rotatably installed and that scans the laser beam. A polygon mirror that reflects the light and scans it on the scanning surface, and a bimorph that has a reflective part that reflects the laser light in the optical path of the laser light are provided, and the bimorph is vibrated and deformed when being scanned by the laser light. A barcode reading device characterized in that the laser beam is configured to vibrate in a direction perpendicular to the scanning direction on the scanning surface.