JPH043298Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to an improved optical scanning device.

(Prior Art) Conventionally, in an optical scanning device that irradiates a rotating polygon mirror with light and scans using the reflected light, the central axis of the rotating polygon mirror and the rotation axis coincide with each other.

FIG. 2 shows the configuration of a conventional optical scanning device. 1 is a rotating polygon mirror, 2 is a driving means for rotating the rotating polygon mirror 1, and 2a is a rotating shaft. The rotating polygon mirror 1 has a rotating shaft 2a located at its center. 3 is a light source (for example, a laser);
The light 4 incident on the rotating polygon mirror 1 is reflected by a reflective surface formed on the side surface of the rotating polygon mirror 1. For example, the light 4 incident on the information pattern surface 5
reach. Here, since the rotating polygon mirror 1 is rotating as shown by arrow A, the reflected light is transmitted to the information pattern surface 5.
The top is scanned in the direction of arrow B in FIG. 2a.

(Problems to be Solved by the Invention) By the way, when the central axis of the rotating polygon mirror and the rotation axis coincide with each other as in this conventional example, a constant location on the information pattern surface 5 is always scanned. That is, in the case of FIG. 2b, a position distanced h from a plane perpendicular to the reflecting surface of the rotating polygon mirror is scanned. Now, when a bar code as shown in FIG. 3a is scanned in the direction of arrow D, the scanning line is always D. However, at this time, if there are voids 6, spots 7, scratches 8, etc. on the scanning line D, as shown in Figure 3b, which is an enlarged view of part S in Figure 3a, accurate information cannot be obtained. do not have. Furthermore, it is necessary to precisely align the scanning line with the desired position of the information pattern. Further, when the information pattern vibrates at a certain frequency, for example when a non-detection object is being conveyed by a conveyor or the like, it is difficult to scan by following the vibration.

The present invention solves the above problems and provides an optical scanning device that can periodically change the scanning location within a certain width range to obtain correct information.

(Means for solving the problem) In order to achieve the above purpose, the rotating polygon mirror is provided with a rotation axis that is eccentric from the central axis, and at an angle other than perpendicular to the reflecting surface of the rotating polygon mirror. It is configured to allow light to enter.

(Function) According to the above configuration, each time the rotating polygon mirror rotates and the reflective surface changes, the distance between the reflective surface and the light source changes, and as a result, the scanned area of the reflected light is within a certain width range. It changes periodically. Therefore, even if there are voids or blemishes on one scan line, they are not on other scan lines, and by combining multiple scan results,
Accurate information can be obtained.

(Example) Hereinafter, an example will be described in detail based on the drawings. FIG. 1 shows an embodiment of the present invention, in which the same reference numerals as in FIG. This is a rotating polygon mirror. The light source 3 causes light to enter the reflective surface of the rotating polygon mirror 11 from a position forming a certain angle θ from a perpendicular surface.

When the above configuration is operated, the light reflected by the reflecting surface 11a of the rotating polygon mirror 11 forms a scanning line on the information pattern surface 5, and the rotating polygon mirror 11
The light reflected by the reflecting surface 11b after turning half a rotation forms a scanning line at q on the information pattern surface 5. There is a width of W between p and q, and the reflective surfaces 11a and 11
A scanning line formed by the light reflected by the reflective surface between the lines b is formed within the range of the width W.

In this embodiment configured as described above, for example, when scanning a barcode, a plurality of different locations are scanned within the width of W, so that voids 6 or the like as shown in FIG. Spot 7,
Alternatively, even if there is a flaw 8, accurate pattern information can be read by setting the pattern with high frequency as the true pattern rather than the most other scanning locations.

Note that if the method of the present invention is used, there is no need to accurately match the scanning position as in the conventional method, and there is no need to follow the vibration of the non-detection object.

By further developing the technology of the present invention and sub-scanning an image using a large number of scanning lines as shown in Figure 4, the entire image information can be read correctly even if there are voids or blemishes on intermediate scanning lines. becomes possible.

(Effects of the Invention) As explained above, the present invention has the advantage that accurate information can be obtained by periodically changing the scanning location within a certain width range.

[Brief explanation of the drawing]

Fig. 1 is a block diagram of an embodiment of the present invention, Fig. 2 is a block diagram of a conventional example, Fig. 3 is a diagram showing the problems of the conventional example, and Fig. 4 is a diagram showing the development of the present invention. FIG. 3 is a diagram showing reading of an information pattern. 2... Rotation drive means, 2a... Rotating shaft, 3...
Light source, 5... Information pattern surface, 11... Rotating polygon mirror, E... Central axis.

Claims (1)

[Scope of utility model registration request] An optical scanning device comprising: a rotating polygon mirror having a rotation axis eccentric from a central axis; and a light source that causes light to enter at an angle other than perpendicular to the reflecting surface of the rotating polygon mirror.