JPH02155106A - Lighting system - Google Patents

Abstract

PURPOSE:To uniformize lighting even if an object of lighting being an uneven surface, by installing a pyramidal shape portion in the title system. CONSTITUTION:A pyramidal shape portion 28 formed of a conical or poly- pyramidal diffusing plate 26 having its diameter of a degree as large as that of an object of lighting is installed in the title system, then it diffuses light from a ring-shaped light source 24 for lighting up the object of lighting while reflecting and diffusing again light reflected from the object of lighting to light it up again. A uniform lighting can be accordingly made even if the object of lighting has its uneven surface. Thus, a processing circuit can be structurally simplified without making it necessary to consider light and shade resulting from the uneven surface of the object of lighting even in case of processing image pickup signals relative to the object of lighting.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an illumination device that illuminates by diffusing light from an annular light source.

[Prior Art] In production lines for canned juice and canned beer, the product number and manufacturing date attached to the bottom of the can are read as necessary. In addition, cans may be inspected for defects in order to eliminate defective cans. In either case, an image of the can is captured by, for example, a COD camera, and the captured image is processed to read the product number and date of manufacture, and to inspect the can for defects.

When imaging with a COD camera, a dedicated lighting device is used to illuminate the can. For example, a conventional lighting device that illuminates the bottom 12 of the can 10 is shown in FIG.

A lighting system [20 and an imaging device 3] are installed on the production line (not shown).
0 is provided, the bottom portion 12 of the can 10 flowing on the production line is illuminated by the illumination device 20, and an image thereof is taken by the imaging device 30. In the illumination device 20, a strobe annular light source 24 is housed in a frame 22, and a diffuser plate 26 is attached to the lower part of the frame 22.

A hole for imaging is formed in the center of this diffuser plate 26. Frame 22 is an imaging bag! 30, and a CCD camera 34 and a lens system 36 are housed within the housing 32.

When the can 10 is directly under the lighting device 20, the annular light source 24 emits light, and the light diffused by the diffuser plate 26 illuminates the bottom 1 of the can 10.
The reflected light from the bottom 12 of the can 10 passes through the hole in the diffuser plate 26 and enters the lens system 36 and CCD camera 34, so that the bottom 12 of the can 10 is imaged.

If the bottom 12 of the can 10 to be illuminated is flat, uniform illumination can be achieved by the conventional illumination device 20. However, in recent years, there have been various types of bottom shapes for canned beer and canned juice, and there has been a problem that uniform illumination cannot be achieved if the bottom has large irregularities. That is, the third
When the recess 14 is formed in the center of the bottom 12 of the can 10 as shown in the figure, there is a problem in that the recess 14 is darker than the surrounding area.

When reading the characters written on the bottom 12 of the can 10 as shown in FIG. 4(a), the image signal becomes as shown in FIG. 4(b) because the central recess 14 is dark. It is not possible to appropriately determine the threshold value for converting into a value.In other words, if the threshold value Va is set so that the characters in the peripheral part can be read, the entire recessed part 14 becomes dark, and if the threshold value vb is set so that the characters in the recessed part 14 can be read. Characters on the periphery cannot be read.

[The problem that the invention tries to solve! ] As described above, the conventional illumination device cannot uniformly illuminate an object to be illuminated that has large irregularities, such as the bottom of a can, and therefore has a problem in that it is not possible to take a good image of the object to be illuminated.

The present invention has been made in consideration of the above circumstances, and an object of the present invention is to provide a lighting device capable of uniformly illuminating even an uneven object to be illuminated.

[Means for Solving the Problems] The above object is to provide a lighting device that illuminates an object by diffusing light from an annular light source to an object to be illuminated, in which the light diffusion section has a light beam of the same degree as the object to be illuminated. It has a bell-shaped portion formed by a conical or polygonal pyramid-shaped diffuser plate with a diameter of the same size,
This is achieved by a lighting device characterized in that the direction in which the bell-shaped portion expands is directed toward the object to be illuminated.

[Function] According to the present invention, a key-shaped portion formed of a conical or polygonal pyramid-shaped diffuser plate having a diameter comparable to that of the object to be illuminated is provided to diffuse the light from the annular light source. In addition to illuminating the illuminated object, the light reflected by the illuminated object is reflected and scattered again to illuminate the illuminated object, so even if the illuminated object is uneven, it can be illuminated uniformly. .

[Embodiment] FIG. 1 shows a lighting device according to an embodiment of the present invention.
Components that are the same as those in the figures are given the same reference numerals, and descriptions thereof will be omitted.

In the illumination device 20, the frame 22 is located only on the outside, and an annular light source 24 is housed in a space defined by the frame 22 and the conical portion 28. As shown in FIG. 1, the bell-shaped portion 28 is a conical member having an inclination angle θ of approximately 30 degrees and is made of a diffuser plate material. A diffusion plate 2 is installed at the bottom of the frame 22.
6 is attached, the size of the hole almost matches the size of the bottom of the bell-shaped part 28, and the can 1 which is the object to be illuminated is
It is desirable that the diameter be approximately the same as the diameter of 0.

When the can 10 having irregularities was illuminated using the illumination device 20 of this example, it was possible to illuminate with uniform brightness regardless of the shape of the bottom 12 of the can 10.

For example, even a can 10 with a concave bottom 12 in the center, which could not be illuminated uniformly in the past, now has uniform brightness.

This is due to the provision of the conical shaped portion 28.

Diffused light from the annular light source 24 passes through the diffuser plate 26 and reaches the bottom 12.
However, with only the diffused light passing through the diffuser plate 26, the concave portion 14 is dark and the peripheral portion is bright, as in the conventional case.

However, due to the presence of the cone-shaped portion 28, the illumination of the recessed portion 14 is strengthened and the illumination becomes uniform. This is due to the following reasons. First, the light reflected from the bottom 12 of the can 10 is reflected and scattered again by the conical portion 28 to illuminate the bottom 12. The reflected and scattered light mainly illuminates the central recess 14. . Second, from the annular light 7124 the bell-shaped portion 28
This is because the light diffused through it also illuminates the bottom 12.

The recess 14 in the center is illuminated by the diffused light from the bell-shaped portion 28.
is illuminated more strongly.

FIG. 2(a) shows the bottom part 12 of the can 10 illuminated by the illumination device of this embodiment, and FIG. 2(b) shows the imaging signal of the bottom part 12. Although there are some dark areas at the peripheral border of No. 14, the illumination is almost uniform. Therefore, by setting the threshold value to Vc, it is possible to easily read characters written over the recessed portion 14 and the surrounding area.

The present invention is not limited to the above embodiments, and various modifications are possible.

For example, in the above embodiment, the angle of inclination θ of the conical portion 28 is rarely about 30 degrees, but it may be any angle other than 30 degrees as long as it is not close to 0 degrees or 90 degrees.

Further, in the above embodiment, the position of the cone-shaped portion 28 almost coincides with the position of the annular light source 24, but it may be moved upward or downward. It may be located closer to a certain can 10, or conversely, it may be located closer to the CCD camera 34.

Furthermore, although the shape of the cone-shaped portion is conical in the above embodiment, uniform illumination can be similarly achieved with a polygonal pyramid shape.

Further, in the above embodiment, a case has been described in which a can having a recessed portion in the center is illuminated, but even a flat bottom can of course be uniformly illuminated, and even a more uneven bottom can be uniformly illuminated. Furthermore, the present invention can be applied to the case of illuminating something other than the bottom of a can.

Further, the annular light source is not limited to a strobe, but may be another light source such as a fluorescent lamp or a light source in which light emitting diodes are arranged in an annular shape.

Note that the bell-shaped portion may be attached to the tip of the lens system of the imaging device instead of the illumination device.

[Effects of the Invention] As described above, according to the present invention, since the bell-shaped portion is provided,
Even if the object to be illuminated has unevenness, it can be illuminated uniformly. Therefore, even when processing an image signal of an illuminated object, there is no need to consider brightness and darkness due to unevenness, and the processing circuit can be simplified.

[Brief explanation of the drawing]

Figures 1 fa) and fb) are a cross-sectional view and a bottom view of an illumination device according to an embodiment of the present invention, respectively, and Figures 2 (a) and (b) are respectively a can bottom illuminated by the same illumination device and its imaging. FIG. 3 is a cross-sectional view of a conventional illumination device, and FIGS. 4(a) and 4(b) are diagrams showing the can bottom illuminated by the same illumination device and its imaging signal, respectively. DESCRIPTION OF SYMBOLS 10... Can, 12... Bottom, 14... Recessed part, 20... Illuminating device, 22... Frame, 24... Annular light source, 26... Diffusion plate, 28... Bell Shape section, 30... Imaging device, 32... Housing, 34... COD camera, 36... Lens system. Figure 1 Chaos Figure 4

Claims (1)

[Claims] In an illumination device that diffuses light from an annular light source to an illuminated object using a light diffusing section, the light diffusing section has a conical shape or a polygonal pyramid-shaped diffuser with a diameter comparable to that of the illuminated object. An illumination device comprising a cone-shaped part formed of a plate, and an expanding direction of the cone-shaped part faces the object to be illuminated.