Optics: measuring and testing – Inspection of flaws or impurities – Transparent or translucent material
Patent
1999-01-25
2000-06-06
Font, Frank G.
Optics: measuring and testing
Inspection of flaws or impurities
Transparent or translucent material
3562391, 3562392, 3562395, 3562396, G01N 2100
Patent
active
060725753
DESCRIPTION:
BRIEF SUMMARY
FIELD AND BACKGROUND OF THE INVENTION
This invention relates to a device for inspecting bottles or the like, with a light source, an image recording element with a respective image analyzing device and a one-piece optical body made of a transparent material. Such a device is known from Unexamined European Patent No. 657,732. The device shown in various modifications in FIGS. 11 through 14 of this document has a ring-shaped optical body with an input and output surface for the optical beam paths. The internal and external ring surfaces of the body are mirrorized, so that an optical beam coming from the bottle is deflected in the direction of the image recording element by reflection after entering the optical body. The required coating of the body on the surfaces provided for reflection is not inexpensive. The optical body becomes useless if the coating is scratched during assembly or operation, and then it must be replaced. Another disadvantage of this inspection device is derived from the fact that the opposing reflective surfaces must be arranged at the same heights, thus requiring a relatively great distance between the imaging body and the side wall of the bottle mouth to be imaged. In addition, the side wall area of the mouth to be inspected can be detected only from an unfavorable angle, so the imaging quality is limited. Furthermore, all the light, even stray light, entering the optical imaging body is reflected. This device is also incapable of label inspection or the like, i.e., checking labels attached to the body of the bottle.
SUMMARY OF THE INVENTION
Consequently, the object of the present invention is to improve on an inspection device in this regard.
This object is achieved by the fact that the one-piece optical body made of a transparent material has a contour designed so that a full-range optical beam path coming from the lighted bottle to be imaged is deflected repeatedly by means of total reflection within the optical body on the path to the image recording element in its passage through the optical body. Because of the design of the body contour causing repeated total reflection of the optical beam, no opaque reflecting surfaces are necessary, so this reduces the manufacturing cost. According to one embodiment of the invention, the surfaces of the optical body causing the total reflection are arranged advantageously at offset heights to one another with at least triple total reflection so that the portions of a bottle to be inspected in the full circumference can be detected from a more advantageous angle. This embodiment is especially advantageous in inspection of a thread.
Since mirrorized surfaces are unnecessary, in contrast with the known related art, the peripheral areas of the bottle to be inspected are lighted from above through the optical body, with the advantage that problem-free ring lighting can be achieved, and secondly, undefined beams of light which are unwanted for the inspection are not reflected in the direction of the image recording element when the limiting angle which is definitive for the total reflection is exceeded, but instead such light can escape the optical body to the outside.
BRIEF DESCRIPTION OF THE DRAWINGS
Preferred embodiments are explained below on the basis of the figures, which show:
FIG. 1a is a vertical section through an optical body for the mouth side wall inspection of bottles, especially with a screw thread;
FIG. 1b is a second embodiment of an optical body with which it is also possible to inspect the inside wall, the bottom and the mouth sealing surfaces of transparent bottles;
FIGS. 1c through 1e is an optical body corresponding to FIG. 1a with a second concentric optical body in three different embodiments, and
FIGS. 2a through 2d is a vertical section through an optical body for imaging the side wall of a bottle.
DESCRIPTION OF THE PREFERRED EMBODIMENT
The rotationally symmetrical body 4 shown in FIG. 1a is arranged coaxially below a CCD camera 2 pointing down. The image is recorded at the moment when an empty bottle 1 to be in
REFERENCES:
patent: 4025201 (1977-05-01), Deane
patent: 4249075 (1981-02-01), Lovalenti
patent: 4750035 (1988-06-01), Chang et al.
patent: 4914289 (1990-04-01), Nguyen et al.
patent: 5536935 (1996-07-01), Klotzsch et al.
Abstract of Japanese Publlication No. 04297810 of Mitsubishi Materials Corp.
International Search Report (PCT Forms 220 and 210).
Font Frank G.
Krones AG
Punnoose Roy M.
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