JPS63180184A - Bar code reader - Google Patents

Abstract

PURPOSE:To surely read bar codes eve though the position of the bar code is shifted rectangularly to the scanning direction, by attaching a polygon mirror to a motor rotary shaft with a tilt of a fine angle so that a scanning line can reach a direction crossing the scanning direction. CONSTITUTION:Light emitted from a laser light source 26 is condensed by a condenser lens 27 and projected on a reflecting surface 38 of a polygon mirror 28 to be reflected in the direction where a bar code exists. The mirror 28 is rotated by a motor 29 and therefore the light reflecting angle varies. Thus the code 24 is scanned. The reflected light received from the code 24 is received by a photodetecting element 33 via a photodetecting lens 32 and the photoconverted signals are sent to a decoder for reading. The center of the inner diameter of the mirror 28 is different from an axis 34 of the motor 29 by a fine angle theta and therefore, the scanning light beam varies rectangularly to the scanning direction. Thus the code 24 can be surely read even though the position of the code 24 is shifted in the direction crossing the scanning direction.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a barcode reading device of a type using a polygon mirror.

(Prior Art) Conventionally, as this type of barcode reading device, there is a type using a polygon mirror.

Figure 5 shows an overall view of such a barcode reading device using a polygon mirror, in which 1 indicates a conveyor, 2
3 is the baggage being carried on conveyor 1, and 3 is baggage 2.
A barcode 4 is attached to this label 3. On the other hand, 5 is a scanner of a barcode reading device, and more specifically, as shown in FIG. 6 and FIG. The light is irradiated onto a polygon mirror 8 having a reflective surface. By rotating this polygon mirror 8 with a motor 9, the above-mentioned irradiation light is transmitted to the barcode 4.
and both limit positions 10a, 10b.
The space between the barcodes 4 is scanned in the direction in which the barcodes 4 are arranged. The light reflected from the barcode 4 is received by the light receiving element 12 via the light receiving lens 11, and the photoelectrically converted signal is sent to a decoder (not shown) for reading. In the case of the above-mentioned conventional device, the scanning line by the scanning light is shown by the straight line 13 in FIG. If 113 matches the position of barcode 4, it can be read without any problem.

(Problem to be Solved by the Invention) However, as shown in FIG. 8, when the label 3 is attached at a different position and the barcode 4 is shifted in the direction crossing the scanning direction (downward in the figure), , barcode 4 is scan line 1
It doesn't match 3. Therefore, there arises a problem that the labels cannot be read, and this poses a problem in that the position at which the label 3 is attached must be strictly controlled.

Therefore, in order to solve the above-mentioned drawbacks, the Japanese Patent Publication No. 59-9947
As shown in the above publication, a method has also been invented in which a plurality of scanning lines 13 are generated in a direction intersecting the scanning direction by tilting the rotation axis at a slight angle with respect to the central axis of the polygon mirror.

However, polygon mirrors are mirror-finished based on the central axis. Therefore, if you try to tilt the center axis with respect to the mirror surface, you will need to rework the center hole after finishing the mirror surface machining. This has the drawbacks of damaging the mirror surface that has already been machined, and causing vibration due to the unbalance due to the tilted central shaft hole, which can damage the motor bearing and adversely affect the optical system. Ta.

Therefore, an object of the present invention is to separate the main body of the polygon mirror from the boss and tilt the central axis hole of the boss at a slight angle with respect to the central axis hole of the polygon mirror. To provide a bar code reading device that does not generate vibrations, etc. by using a boss to correct unbalance caused by tilting the center shaft hole.

[Structure of the Invention] (Means for Solving the Problems) The barcode reading device of the present invention separates a polygon mirror main body and a boss, and tilts the central axis hole of the boss at a slight angle with respect to the central axis hole of the polygon mirror. The feature is that the unbalanced vibration caused by this is corrected on the boss side.

(Function) Since the central axis hole of the polygon mirror and the central axis hole of the boss are tilted at a slight angle, the reflective surface of the polygon mirror is tilted with respect to the rotation axis, so the scanning line is also tilted in the direction that intersects the scanning direction. It can be spread evenly, and it can be easily processed and unbalance can be easily corrected. Furthermore, the mounting angle θ can be changed by replacing the boss.

(Embodiment) An embodiment of the present invention will be described below with reference to FIGS. 1 to 4. First, in FIG. 3, 21 is a conveyor, 22 is a load carried on the conveyor 21, 23 is a label affixed to the load 22, and 24 is a label 2.
This is the barcode attached to 3. On the other hand, 25 is a scanner, which will be explained below with reference to FIGS. 1 and 2. 26 is a laser light source, and the light emitted from this laser light source 26 is focused by a condenser lens 27 and irradiated onto a polygon mirror 28. This polygon mirror 28 is rotated in the direction of arrow B by a motor 29, and the scanning light reflected by the polygon mirror 28 heads in the direction where the barcode 24 is located, and reaches both limit positions @30a, 30b is scanned in the direction in which the barcodes 24 are lined up to form a scanning line 31 in the direction of arrow C (see FIG. 3). And barcode 24
The reflected light is received by the light receiving element 33 via the light receiving lens 32, and the photoelectrically converted signal is sent to a decoder (not shown) and read. As shown in FIG. 1, the boss 35 fitted to the motor shaft 34 and the polygon mirror 28 fitted thereto are arranged so that the axes of the motor shaft 34 and the polygon mirror 28 are tilted by an angle θ° as shown in FIG. ing. The boss 35 is made of a material having a higher specific gravity than the polygon mirror 28, and has a balance hole 36 for correcting imbalance caused by the tilt of the axis. The polygon mirror 28 and the boss 35 are fixed with a set screw 37.

Next, the operation of the above configuration will be explained. First, as described above, the light emitted from the laser light source 26 passes through the condensing lens 27.
The light is condensed and irradiated onto the reflective surface 38 of the polygon mirror 28, where it is reflected in the direction where the barcode 24 exists. Since this folding polygon mirror 28 is rotated in the direction of arrow B by a motor 29, as the rotation progresses, the reflection angle of the light changes, so that the scanning light for the barcode 24 is directed to the arrow C where the barcode 24 is lined up. scanned in the direction.

Then, the reflected light from the barcode 24 is transmitted to the light receiving lens 32.
The light is received by the light receiving element 33 via the light receiving element 33, and the photoelectrically converted signal is sent to a decoder for reading and scanning.

By the way, as an example, the eight reflecting surfaces 38 have different angles θ with respect to the center of the inner diameter of the polygon mirror 28 and the shaft 34 of the motor 29. For example, the scanning light reflected from the downward reflecting surface 38 at an angle θ shown in FIG.
2, and when the angle θ shown in FIG.
The scanning light is reflected from the reflecting surface 38 whose angle θ is upward as shown in FIG.
Scan the upper part of 2. Therefore, polygon mirror 2
During one rotation of 8, a plurality of scanning lines 31 can be made to alternate in a direction intersecting the scanning direction.

According to the above embodiment, during one rotation of the polygon mirror 28, a plurality of reflecting surfaces 38 having different angles θ with respect to the shaft 34 of the motor 29 provided around the polygon mirror 28 are formed.
Accordingly, the scanning line 31 can be spread in a direction intersecting the scanning direction. Therefore, even if the barcode 24 deviates from the reference position in the cross direction, it can be read reliably, and therefore the position of the label 23 should not be strictly controlled as in the past. becomes unnecessary. Furthermore, even if a plurality of reflective surfaces having different angles θ with respect to the axis 34 of the motor 29 are formed around the polygon mirror 28 as described above, the polygon mirror 28
It is only necessary to tilt the axis of the boss 35 to which the polygon mirror 28 is attached at an angle θ with respect to the axis of the polygon mirror 28, and the processing of the polygon mirror 28 itself may be the same as the conventional method. Therefore, the mirror surface (reflection surface 38) of the polygon mirror is less likely to be damaged, unlike the conventional method disclosed in Japanese Patent Publication No. 5.9-9947, in which the in-shaft body of the polygon mirror is directly tilted. Also, boss 3
In machining No. 5, since the boss 35 does not have a mirror-finished portion, there is no need to pay much attention to machining the shaft hole. When the balance is corrected by the weight reduction method, since the boss 35 is made of a material with a specific gravity heavier than that of the material of the polygon mirror 28, only a small amount of volume needs to be removed to correct the unbalanced weight. In general, when correcting the balance, a dummy polygon mirror for testing is attached and the balance is corrected, so the polygon mirror in actual use is not used, so there is no damage to the mirror surface (reflection surface 38) of the polygon mirror.

ISENI () -) 1r Example) In the above explanation, the balance correction method has been explained as a weight loss method, but the same effect can be achieved even if the weight increase method is applied. In addition, when using the l increase method, it is preferable that the material of the boss has a specific gravity equal to or lighter than that of the polygon mirror.

[Effects of the Invention] According to the present invention, the polygon mirror is mounted through the boss so as to be inclined at an angle θ with respect to the rotation axis of the motor, so that the scanning line can be spread in a direction intersecting the scanning direction. Not only can the barcode be reliably read even if the barcode is misaligned in a direction crossing the scanning direction, but polygon mirrors in particular can be processed easily as before. In addition, since the polygon mirror and motor axis are tilted, unbalance can be easily corrected using the boss, which prevents early damage to the motor bearings and vibrations that adversely affect the optical system. It has excellent effects.

Furthermore, by changing the boss, the mounting angle θ can be changed.

[Brief explanation of the drawing]

1 to 4 show one embodiment of the present invention, in which FIG. 1 is a side view from the scanner to the barcode, FIG. 2 is a plan view, FIG. 3 is a perspective view, and FIG. Figures (a) to (C) are views corresponding to Figure 1 in different states for explaining the operation, and Figure 5 is a view corresponding to Figure 3 of the conventional structure, and Figures 6 and 7 are the same. Figures 1 and 2 equivalent figures, No. 8
The figure is a diagram equivalent to Figure 3 showing the problem state of the same structure. In the figure, 24 is a barcode, 28 is a polygon mirror, 29
34 is a motor, 35 is a boss, 36 is a balance hole, 37 is a set screw, and 38 is a reflective surface (mirror surface). Agent Patent Attorney Nori Chika Ken-Kan Shu Hiroshi Mitsumata Collection 2 Figure 5 tA4!2! Figure 5 Figure 7

Claims (1)

[Claims] A rotating polygon mirror having a plurality of reflective surfaces on its periphery is provided, and the polygon mirror is irradiated with light emitted from a light source, and each of the reflective surfaces reflects the light in the direction of the barcode. The polygon mirror is separated into a polygon mirror body and a boss, and the axis of rotation of the boss is tilted by an angle θ with respect to the axis of the polygon mirror. When correcting the unbalance by using the weight loss method, the specific gravity of the boss material is made larger than that of the polygon mirror material.
A barcode reading device characterized in that the specific gravity of the boss material is the same or lower when using the bulking method.