JPH062462U - Bar code reader optical system - Google Patents

Abstract

(57) [Abstract] [Purpose] This invention prevents the occurrence of a reading error by projecting and irradiating a barcode label with a uniform intensity. According to the present invention, a cylindrical lens 4 having a specific shape is provided along the width direction of the bar 8 on the optical path toward the bar code label 7, and the amount of light incident on each bar 8 is made uniform.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to an optical system of a bar code reader that can make the amount of light incident on each bar on a bar code label uniform.

[0002]

[Prior art]

 Various barcode readers have been developed as means for reading barcodes. For example, in a stationary bar code reader, as shown in FIG. 11, the beam light emitted from a semiconductor laser (LD) 100 serving as a light source is converged by a converging lens 101, and a polygon mirror 102 is swung to a predetermined width to scan a bar code label. It is known that the light is projected toward 103 and is irradiated while scanning in the bar width direction.

[0003]

[Problems to be solved by the device]

By the way, as shown in FIG. 12, the light beam emitted from this bar code reader has a Gaussian distribution (normal distribution) in which the light intensity at the central portion W _C is maximum and the light intensity at both end portions W _E is greatly reduced. However, since there is a large unevenness in the intensity distribution, there is a problem in that the return rate also has unevenness and reading errors occur. Therefore, in view of the above-mentioned conventional drawbacks, the present invention provides a bar code reader optical system capable of preventing a reading error by projecting and irradiating a bar code label with uniform intensity. It is intended.

[0004]

[Means for Solving the Problems]

 That is, this invention is a bar code reader optical system that irradiates light from a light source onto a bar code label to read the bar code written on the bar code label, and the curvature increases from the center to both ends. A spherical cylindrical lens is provided along the bar width direction on the optical path from the light source to the bar code label so that the amount of light incident on each bar on the bar code label is made uniform.

[0005]

[Action]

 The optical system of the bar code reader of the present invention is provided with a cylindrical lens of a specific shape along the bar width direction on the optical path toward the bar code label so that the beam width in the bar length direction orthogonal to the bar width is It is increased toward both ends in the width direction, whereby the amount of light incident on each bar can be made uniform.

[0006]

【Example】

 An embodiment of the present invention will be described below with reference to the accompanying drawings. FIG. 1 shows an optical system of a bar code reader according to the present invention, which is provided with a cylindrical laser 4 in addition to a conventional semiconductor laser 1, a converging lens 2 and a polygon mirror 3. . In the figure, reference numeral 5 indicates a reflection mirror. As shown in FIG. 2, the cylindrical lens 4 is attached so as to face the window 6A opened in the housing 6 of the bar code reader, and has a shape as shown in FIG. That is, as shown in FIG. 4, the cylindrical lens 4 of this embodiment uses an aspherical lens having a substantially K-shaped longitudinal section, and the central portion 4A has the thinnest thickness and is directed toward both end portions 4B and 4C. Is formed so that the wall thickness increases. In the cylindrical lens 4, the outer surface from the central portion 4A to the both end portions 4B and 4C has a curved surface, particularly on the surface facing the barcode label 7, as shown in FIGS. In addition, the curvature (radius of curvature) increases (decreases) from the center toward the end.

Therefore, according to this embodiment, when the beam light from the semiconductor laser (LD) 1 which is the light source passes through the cylindrical lens 4, the light intensity at which the central portion W _C is maximum is shown in FIG. So that it is evened out. As shown in FIG. 10, the beam light after passing through the cylindrical lens 4 is projected and illuminated with a shape distribution in which the bar ends of the bar code label 7 of each bar 8 are elongated in the longitudinal direction.

[0008]

[Effect of device]

 As described above, according to the optical system of the bar code reader according to the present invention, the aspherical cylindrical lens is provided in parallel along the bar width direction on the optical path toward the bar code label, and the bar code label is provided. Since the amount of light incident on the bar is made uniform, it is possible to irradiate each bar described in the bar code label with a substantially constant amount of light, and it is possible to effectively prevent the occurrence of reading errors.

[Brief description of drawings]

FIG. 1 is a configuration diagram showing an optical system of a bar code reader according to the present invention.

FIG. 2 is a perspective view showing a state where the cylindrical lens according to the present invention is attached to a barcode reader.

FIG. 3 is a perspective view showing a cylindrical lens according to the present invention.

FIG. 4 is a sectional view of the cylindrical lens shown in FIG.

5 is a sectional view of the cylindrical lens shown in FIG. 3, taken along the line II-II.

6 is a sectional view of the cylindrical lens shown in FIG.
FIG.

7 is a cross-sectional view taken along the line IV-IV of the cylindrical lens shown in FIG.

8 is a cross-sectional view of the cylindrical lens shown in FIG. 3, taken along the line VV.

FIG. 9 is a graph showing a state in which the beam light intensity distribution is made uniform by the optical system of the barcode reader according to the present invention.

FIG. 10 is an explanatory view showing the shape of the wavefront of the light beam projected on the barcode label by the optical system of the barcode reader according to the present invention.

FIG. 11 is a configuration diagram showing an optical system of a conventional barcode reader.

FIG. 12 is a graph showing the intensity distribution of beam light when an optical system of a conventional barcode reader is used.

[Explanation of symbols]

 1 Light source (semiconductor laser) 4 Cylindrical lens 7 Bar code label

Claims (1)

[Scope of utility model registration request] 1. An optical system of a bar code reader for irradiating a bar code label with light from a light source to read a bar code written on the bar code, wherein an aspheric surface whose curvature increases from a central portion toward both ends. A cylindrical lens having a shape is provided along the bar width direction on the optical path from the light source to the bar code label, and is configured to equalize the amount of light incident on each bar on the bar code label. Optical system of barcode reader.