JPH06295353A - Bar code reader - Google Patents

Abstract

PURPOSE:To easily work a hole to be engaged with the rotary shaft of a polygon mirror having plural mirror faces, to suppress the generation of a positional deviation by improving weight balance and to attain effective scanning. CONSTITUTION:Since a hole 3A to be engaged with the rotary shaft 2 of the polygon mirror 3 is fixed so as to be inclined from the rotary shaft 2 in a convensional method, the working of the hole 3A is difficult because the hole 3A should be drilled with an angle theta from the horizontal face L of the mirror 3. However this example can easily execute drilling work by setting up the diameter (r1) of the hole 3A larger than the diameter (r) of the rotary shaft 2 (r1>r) while previously estimating the angle 8 so that the vertical drilling of the hole 3A to the horizontal face L can be executed. When the inclining position of the mirror 3 is selected, approximately uniform scanning can be attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a bar code reader having an improved polyhedral mirror (hereinafter also referred to as a polygon mirror) which has a plurality of mirror surfaces and reflects a laser beam emitted from a laser diode to form a scanning beam.

[0002]

2. Description of the Related Art FIG. 11 is a schematic view showing a conventional example of this kind, in which 8 is a bar code, 20 is a motor 1, a rotary shaft of the motor 2, a polygon mirror 3, a laser diode 6 as a light source 6, a lens 7, and a light receiving. A bar code reader 30 including a lens 14, a light receiving element 15, an amplifier 16, a waveform shaper 17, and the like, and a decoder 30 for decoding the bar code. Further, 19 is a scanning beam and 31 is a reading result. That is, in the conventional bar code reader, the laser light emitted from the laser diode 6 is focused by the light projecting lens 7, is applied to the polygon mirror 3 rotated by the motor 1, and is scanned with the laser light. The reflected light of the obtained laser light is guided to the light receiving element 15 via the light receiving lens 14, where the light is converted into an electric signal to read the information of the bar code 8.

By the way, in the bar code reader shown in FIG. 11, one scanning line is formed. This one optical scanning beam is shown by reference numeral 19 in FIG. 12, but if it happens that the dirt 8a, scrap 8b, etc. of the bar code 8 is scanned, it becomes unreadable or erroneous. Therefore, there is also a raster scanning method in which a plurality of scanning beams are formed instead of one scanning beam, and reading is possible by a majority method. FIG. 13 is a schematic view showing such a bar code reader.

As is clear from FIG. 13, this system is designed to support the polygon mirror 3 by inclining it by a certain angle with respect to the rotation axis of the motor 1. The tilt angle of each mirror surface of the polygon mirror 3 is changed for each surface, and the scanning position of the laser beam is changed accordingly, so that the barcode can be raster-scanned with a certain width. As a result, even if the bar code 8 has a stain 8a, a scrape 8b, or the like as shown in FIG. 14, it is possible to correctly read with either scanning beam. In addition, 9 (9a-
9f) shows a scanning light beam group.

[0005]

FIG. 15 is a sectional view for explaining a mounting mode of a polygon mirror. As is clear from this figure, the polygon mirror 3 is attached to the motor 1
In order to engage with, it is necessary to incline the hole 3A of the polygon mirror 3 with respect to the axial center of the polygon mirror 3 to make a hole, which makes machining including the hole position extremely difficult and costly. There's a problem. In particular, if the drilling position shifts, there is a problem that the weight balance is lost when the polygon mirror 3 is attached, the rotation of the motor is increased, and the life of the motor is shortened. Therefore, an object of the present invention is to make the structure relatively simple, and to improve the weight balance to improve the reliability.

[0006]

In order to solve such a problem, in the first invention, a polygon mirror which is composed of a plurality of mirror surfaces and reflects a laser beam emitted from a laser diode to form a scanning beam, and the polygon mirror. A support member for supporting the mirror and a rotation drive means for rotating the polygon mirror via the support member are provided, and the center axis of the polygon mirror is supported by inclining the center axis of the rotation drive means by a predetermined angle. In the bar code reader
The inside diameter of the polygon mirror is made larger than the central axis of the rotation driving means by an amount corresponding to the tilt angle.

In the second aspect of the invention, a polygon mirror having a plurality of reflecting surfaces that reflects the laser light emitted from the laser diode to form a scanning beam, a pair of support members that sandwich the polygon mirror, and the support member. And a rotation driving means for rotating the polygon mirror through one side of the polygon mirror, wherein the center axis of the polygon mirror is tilted by a predetermined angle with respect to the center axis of the rotation driving means and supported. In the polygon mirror, each of the pair of supporting members is provided with an inclination according to the inclination angle, and one supporting member is provided with respect to the other supporting member.
The feature is that it is attached by rotating it by 80 degrees.

Further, in the first and second inventions, while a concave portion or a hole is provided on both end faces of the polygon mirror,
A convex portion that engages with the concave portion or the hole may be formed on the supporting member (third invention), or through holes may be formed on the polygon mirror and the supporting member, respectively.
A pin can be mounted and fixed in this through hole (fourth invention).

[0009]

[Function] It is necessary to make a hole by tilting the axis of the polygon mirror by making the inner diameter of the polygon mirror attached to the pedestal (supporting member) with an inclination larger than the motor rotation axis according to the inclination angle. To reduce the processing cost by facilitating the processing. When the polygon mirror is configured to be sandwiched by a pair of inclined support members, one support member is rotated 180 degrees with respect to the other support member so that the weight of the polygon mirror section is reduced. The rotation axis is made substantially equal to eliminate blurring during rotation of the motor and prevent the life of the motor from being adversely affected. Further, the polygon mirror and the supporting member are configured to be connectable by the concave-convex portion or the through hole, so that the positional deviation during the rotation of the motor can be prevented.

[0010]

1 is a sectional view showing an embodiment of the present invention.
Is a motor, 2 is a rotary shaft of the motor, and 2A is a flange for a stopper, which is integrally formed with the rotary shaft 2. The end surface 2B of the motor rotating shaft 2 is provided with one or a plurality of fixing screw holes. Reference numeral 3 is a polygon mirror having a mirror surface that reflects laser light. A hole 3A for engaging with the motor rotation shaft 2 is formed at the center of the polygon mirror 3, and the diameter of this hole is increased here according to the inclination angle of the pedestal 4 as a support member. ing.

That is, conventionally, the hole 3A for engaging the motor rotating shaft 2 must be machined with a certain inclination with respect to the horizontal plane L of the polygon mirror 3 as described with reference to FIG. The processing was troublesome, but in this embodiment, a large diameter (diameter r <diameter rl) is obtained by taking this inclination into consideration.
By making a hole, the polygon mirror 3 can be machined perpendicularly to the horizontal plane L. In FIG. 1, 20 is an O-ring, 21 is a holding plate, 2
2 is a small screw. The pedestal 4, the polygon mirror 3, the O-ring 20, and the pressing plate 21 are arranged in this order in the motor rotation shaft 2
After inserting the screw into the end face 2B of the motor rotary shaft 2
By tightening and fixing the polygon mirror 3 to the inclined surface of the pedestal 4 with an angle θ by the pressing plate 21 and the O-ring 20, the polygon mirror 3 is fixed.

FIG. 2 is a sectional view showing a second embodiment of the present invention. This is different from that shown in FIG. 1 in that between the polygon mirror 3 and the O-ring 20, a pressing tool 23 having the same angle as the angle θ of the pedestal 4 is provided.
The feature is that it is installed in a state of being rotated once so that the weight is even with respect to the center of rotation of the motor rotation shaft 2, and the rest is the same as in the case of FIG. It is fixed with a small screw 22. It can be said that the pressing tool 23 has a role as a support member that holds the polygon mirror 3 together with the pedestal 4.

FIG. 3 is a sectional view showing a third embodiment of the present invention. The basic configuration is the same as in FIGS. 1 and 2, but in order to clarify the positional relationship between the pedestal 4 and the pressing tool 23 and the polygon mirror 3, the polygon mirror 3 is provided with, for example, a concave portion 3B. By providing the pedestal 4 and the pressing member 23 with the convex portions 4A and 23A that engage with the pedestal 4 and the pressing member 23, the positional deviation does not occur when the motor rotates. Needless to say, a hole may be formed instead of the concave portion 3B and a convex portion that engages with the hole may be formed.

FIG. 4 is a sectional view showing another embodiment of the present invention. This is a modified example of FIG. 3, and instead of forming the uneven portion on the pedestal 4, the pressing tool 23 and the polygon mirror 3, through holes 3C, 4B and 23B are formed as shown and the pins 24 are attached thereto. Then, it is fixed.

By the way, the position at which the polygon mirror is tilted does not have to be anywhere. In an extreme case, for example, when the vertex position of the polygon mirror or the position where the interior angle of a certain surface is divided into two, the raster light trace of the scanning light beam passes through the same position twice during one rotation of the polygon mirror. Therefore, the number of raster scan lines may be half the number of polygon mirror surfaces. Therefore, in this embodiment, the following measures are taken.

FIG. 5 is an explanatory view for explaining an embodiment in such a case. This shows a polygon mirror. (A) is a top view, (b) is a sectional view taken along the line AA,
This is the case where the number of mirror surfaces is eight. Reference numeral 3 indicates a polygon mirror, 3A indicates a hole, and 3B indicates a concave portion or a hole. That is, here, an example is shown in which the position where the polygon mirror 3 is tilted is an angular position (θx) of 10 to 12 degrees from the vertex position of the polygon mirror 3.

Similarly, when the polygon mirror 3 is a dodecahedron, as shown in FIG.
The angular position (θx) is set to -10 degrees, and more generally, as shown in FIG. 7, the angular position (θx) is approximately ¼ of the internal angle α of the polygon mirror 3 from the vertex position of the polygon mirror 3. 6A is a top view of the polygon mirror,
(B) shows the AA sectional view. 8 and 9 show
It is an explanatory view for explaining an example of a scanning light beam formed by a polygon mirror.

That is, FIG. 8 shows the case where the polygon mirror is an octahedron. As is clear from the figure, θx = 10
It can be seen that the intervals between the scanning light beams are substantially uniform when the angle is -12 degrees. Further, FIG. 9 shows an example in which the polygon mirror has a dodecahedron. In this case, when θx = 8 to 10 degrees, it can be seen that the intervals between the scanning light beams are substantially uniform. Similarly, in the case of an n-face, it can be said that the intervals between the scanning light beams are generally uniform at about 90 / n degrees.

FIG. 10 is a structural diagram for explaining a structural example of the pedestal (or the supporting member) used in the present invention.
For example, in the case of an octahedral polygon mirror, for example, if it is configured as shown in FIG. 3, the concave portion or the hole portion 3B of the polygon mirror 3 as shown in FIG. 10 is formed on the base 4 as shown in FIG. 10 to form a convex portion 4A which engages with the concave portion or the hole portion 3B on the line connecting the center of rotation 4B of the base 4 and the center of the convex portion 4A. In addition, the polygon mirror 3 is tilted according to the tilt angle. In addition, a support member (shown as a holding tool 23 in FIG. 3) having the same structure as the pedestal 4 is turned upside down (upside down) and is attached in a state of being rotated 180 degrees around the rotation center 4B.

The above relationship is not limited to the case where the polygon mirror is an octahedron, but also when the polygon mirror is a 10-sided polyhedron or another polyhedron, basically there is a slight difference in the angular position at which the polygon mirror is tilted. The description is omitted because it is the same as the case.

[0021]

According to the present invention, the inner diameter of the polygon mirror attached to the inclined support member is formed larger than the motor rotation shaft according to the inclination angle of the polygon mirror. There is no need to incline and drill a hole, which facilitates processing and reduces processing cost. Further, if the weight of the polygon mirror part is made uniform with respect to the center of the rotation axis, motor noise is eliminated and it is possible to prevent the life of the product from being adversely affected. If it is configured so that it can be coupled with, it is possible to obtain an advantage that it is possible to prevent a position shift when the motor rotates.

In addition, by making the above arrangement at the position where the polygon mirror is tilted, it becomes possible to perform substantially uniform scanning and improve the reading accuracy. In addition, a convex portion that engages with the concave portion or the hole portion of the polygon mirror is formed on the pedestal, and an inclination according to the inclination angle is provided on the line connecting the center of rotation of the pedestal and the center of the convex portion, and the same structure is used. Since it is turned upside down and rotated by 180 degrees, it is possible to reduce the manufacturing cost for manufacturing the support member including the pedestal, and it is also possible to obtain advantages such as easy parts management by sharing the parts. .

[Brief description of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention.

FIG. 2 is a sectional view showing a second embodiment of the present invention.

FIG. 3 is a sectional view showing a third embodiment of the present invention.

FIG. 4 is a sectional view showing a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram for explaining a fifth embodiment of the present invention (when the polygon mirror is an octahedron).

FIG. 6 is a fifth embodiment of the present invention (where the polygon mirror is 10
It is an explanatory view for explaining (in the case of a face piece).

FIG. 7 is an explanatory diagram for explaining a fifth embodiment of the present invention (when the polygon mirror is a general polyhedron).

FIG. 8 is an explanatory diagram for explaining an example of a scanning light beam formed by an octahedral polygon mirror.

FIG. 9 is an explanatory diagram for explaining an example of a scanning light beam formed by a polygonal mirror of a dodecahedron.

FIG. 10 is an explanatory diagram for explaining a structural example of a pedestal used in the present invention.

FIG. 11 is a schematic diagram showing a conventional example of a barcode reader.

FIG. 12 is an explanatory diagram for explaining the problem of FIG. 11.

FIG. 13 is a schematic diagram showing a conventional example of a barcode reader capable of raster scanning.

14 is an explanatory diagram for explaining the operation of FIG. 13. FIG.

FIG. 15 is a cross-sectional view for explaining an example of a mounting mode of the polygon mirror in FIG.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Motor, 2 ... Motor rotation axis, 3 ... Polygon mirror (multifaceted mirror), 4 ... Pedestal, 6 ... Light source, 7 ... Lens, 8
... bar code, 8a ... dirt, 8b ... blurred, 9,19 ...
Scanning light beam, 20 ... O-ring, 21 ... Holding plate, 22
… Screw screws, 23… Holders, 24… Pins.

Claims (6)

[Claims] 1. A polygon mirror having a plurality of mirror surfaces for reflecting a laser beam emitted from a laser diode to form a scanning beam, a support member for supporting the polygon mirror, and a rotation of the polygon mirror via the support member. A bar code reader comprising: a rotation driving means for driving the polygon mirror, wherein the center axis of the polygon mirror is tilted by a predetermined angle with respect to the center axis of the rotation driving means and supported. The barcode reader is characterized in that it is larger than the central axis of the rotation driving means by the amount corresponding to the above. 2. A polygon mirror which is composed of a plurality of reflecting surfaces and reflects a laser beam emitted from a laser diode to form a scanning beam, a pair of support members sandwiching the polygon mirror, and one of the support members. A rotary drive means for rotationally driving the polygon mirror, wherein the central axis of the polygon mirror is tilted by a predetermined angle with respect to the central axis of the rotary drive means and is supported by the bar code reader. A bar code reader, characterized in that each of a pair of support members is provided with an inclination according to the inclination angle, and one support member is attached by being rotated by 180 degrees with respect to the other support member. 3. The bar according to claim 1, wherein a concave portion or a hole is provided on both end surfaces of the polygon mirror, and a convex portion engaging with the concave portion or the hole is formed on the supporting member. Code reader. 4. The bar code reader according to claim 1, wherein a through hole is formed in each of the polygon mirror and the supporting member, and a pin is mounted and fixed in the through hole. 5. A polygon mirror having a plurality of mirror surfaces for reflecting a laser beam emitted from a laser diode to form a scanning beam, a support member for supporting the polygon mirror, and the polygon mirror rotated through the support member. In a bar code reader comprising: a rotation driving means for driving the polygon mirror, the center axis of the polygon mirror being tilted at a predetermined angle with respect to the center axis of the rotation driving means, and being supported by the polygon mirror. A bar code reader characterized in that an angular position of about a quarter of an inner angle of a polygon mirror is set from a certain vertex position. 6. A polygon mirror, which is composed of a plurality of mirror surfaces and reflects a laser beam emitted from a laser diode to form a scanning beam, a pair of support members sandwiching the polygon mirror, and one of the support members. A bar code reader comprising: a rotation driving unit that rotationally drives the polygon mirror, wherein the center axis of the polygon mirror is tilted by a predetermined angle with respect to the center axis of the rotation driving unit and supported. In addition, a concave portion or a hole is bored from the apex position to an angular position of about 1/4 of the inner angle of the polygon mirror, and a convex portion engaging with the concave portion or the hole is formed on the supporting member, respectively, and one of the supporting members is supported. Inclining the polygon mirror on a line connecting the center of rotation of the member and the center of the convex portion, and turning over the other supporting member having the same structure as this supporting member, Barcode reader, wherein the mounting is rotated 180 degrees about the rotation axis to the polygon mirror.