JP2000028534A - Illumination device for can inside inspection - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device for can inside inspection, capable of improving uniformity of brightness of the inside of a can. SOLUTION: In this illumination device for can inside inspection, for illuminating the inside of a can 1 by a number of spot beams, by arranging a number of optical fibers 2 equally on upper parts at an angle around an opening part 1a of the can 1 in order to photograph and inspect the inside of the can 1, optical axes Lx of the optical fibers 2 are arranged so as to be in contact with a supposed concentric circle 6 in the opening 1a.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lighting device suitable for photographing and inspecting the inner surface of a can.

[0002]

2. Description of the Related Art In order to photograph and inspect the inner surface of a can, a large number of optical fibers are uniformly arranged obliquely upward around the opening of the can to illuminate the inner surface of the can with a large number of spot lights. Japanese Patent Laid-Open No. 62-187841 proposes an optical fiber in which the optical axis of an optical fiber passes through the center of a can.

[0003]

The conventional apparatus has a problem that the uniformity of the brightness on the inner surface of the can is low, and it is difficult to perform a high-precision inspection. The present invention has been made in view of the above circumstances, and has as its object to provide a lighting device for inspecting the inner surface of a can, which can improve the uniformity of brightness of the inner surface of the can.

[0004]

In order to achieve the above-mentioned object, the present invention provides a method for photographing and inspecting an inner surface of a can by arranging a large number of optical fibers around the opening of the can evenly and obliquely upward. In the illumination device for inspecting the inner surface of the can, which illuminates the inner surface of the can with a large number of spot lights, the optical axis of the optical fiber is in contact with a concentric circle assumed inside the opening. According to the present invention, since the optical axis of the optical fiber is configured to be in contact with the concentric circle assumed in the opening, the spot light of the optical fiber travels in a spiral shape while reflecting the inner wall of the can, so that the number of times of reflection is large. The brightness uniformity is improved.

[0005]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a lighting device for inspecting the inner surface of a can according to the present invention will be described below with reference to FIGS. FIG. 1 is a plan view of a lighting device for inspecting the inner surface of a can, and FIG. 2 is a longitudinal sectional view of a lighting device for inspecting the inner surface of a can. 1 and 2, reference numeral 1 denotes a can, and an opening 1a of the can 1
, A large number of optical fibers 2 are evenly arranged obliquely upward. Although FIG. 1 shows only four optical fibers to simplify the drawing, a large number of optical fibers are actually arranged.

The optical fiber 2 is connected to a light source 3 and illuminates the inner surface of the can 1 with a number of spot lights emitted from the optical fiber 2. Above the optical fiber 2, a CCD camera 4 for photographing the inner surface of the can 1 is arranged.
It is connected to the. The optical axis of the CCD camera 4 coincides with the axis of the can 1, and the focal point of the CCD camera 4 is focused on the bottom of the can and below the inner wall. Each of the optical fibers 2 is
The optical axis Lx is disposed so as to be in contact with a concentric circle 6 concentric with the can 1 supposed inside the opening 1 a of the can 1.

Next, the operation of the illumination device for inspecting the inner surface of a can configured as described above will be described. Optical axis Lx of optical fiber 2
Is in contact with the concentric circle 6 assumed inside the opening 1a of the can 1, so that the spot light emitted from the optical fiber 2
As shown in (2), it proceeds in a spiral shape while reflecting the inner wall of the can. Therefore, the spot light incident on the inner wall of the can is reflected many times by the inner wall of the can and reaches the bottom of the can. That is, the number of times of reflection of the spot light on the inner wall of the can increases, and the uniformity of the brightness of the inner surface of the can improves. The bottom surface of the can and the lower portion of the inner wall of the can which are uniformly illuminated in this way are photographed by the CCD camera 4, and the obtained image is processed by the image processing device 5, and the inner surface of the can is inspected.

The inclination angle θ of the optical fiber 2 with respect to the horizontal plane also affects the number of spot light reflections. The smaller the inclination angle θ, the greater the number of reflections. In order to make the light incident on the conical portion located above, the inclination angle θ is selected as small as possible within a range where the spot light is incident on the cylindrical portion below the conical portion of the can 1.

FIGS. 3 and 4 show a second embodiment of the illumination device for inspecting the inner surface of a can according to the present invention. FIG. 3 is a plan view of the lighting device for inspecting the inner surface of a can, and FIG. 4 is a longitudinal sectional view of the lighting device for inspecting the inner surface of a can. 3 and 4, the same members as those in FIGS. 1 and 2 are denoted by the same reference numerals, and description thereof will be omitted.

In this embodiment, the optical fiber 2 is arranged such that its optical axis Lx is in contact with a circle which is the opening 1a of the can 1. The spot light emitted from the optical fiber 2 is set to be incident on the top surface of the opening 1a of the can 1. The focus of the CCD camera 4 is set on the top surface of the opening 1a of the can 1. According to the present embodiment, the scratch 7 formed radially on the opening 1a of the can 1 can be photographed by the CCD camera 4.

[0011]

As described above, according to the present invention,
Since the spot light of the optical fiber travels in a spiral shape while reflecting on the inner wall of the can, the number of reflections increases and the uniformity of brightness improves.

[Brief description of the drawings]

FIG. 1 is a plan view showing a first embodiment of a lighting device for inspecting the inner surface of a can according to the present invention.

FIG. 2 is a vertical sectional view showing a first embodiment of a lighting device for inspecting the inner surface of a can according to the present invention.

FIG. 3 is a plan view showing a second embodiment of the illumination device for inspecting the inner surface of a can according to the present invention.

FIG. 4 is a longitudinal sectional view showing a second embodiment of the illumination device for inspecting the inner surface of a can according to the present invention.

[Explanation of symbols]

 Reference Signs List 1 can 1a opening 2 optical fiber 3 light source 4 CCD camera 5 image processing device 6 concentric circle 7 scratch Lx optical axis of optical fiber

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Akira Fujiwara 1170-14 Kinmeicho, Soka City, Saitama Prefecture Fujitronix F-term (reference) 2G051 AA11 AA13 AB02 AB06 BA01 BB01 BB17 CA04

Claims (1)

[Claims] 1. In order to photograph and inspect the inner surface of a can, a large number of optical fibers are equally arranged obliquely upward around the opening of the can, and the inner surface of the can is illuminated with a large number of spot lights. A lighting device for inspecting a can inner surface, wherein an optical axis of an optical fiber is in contact with a concentric circle assumed in an opening.