GB2061491A

GB2061491A - Bottle Inspection Method and Apparatus

Info

Publication number: GB2061491A
Application number: GB7936313A
Authority: GB
Original assignee: T I FORDS Ltd
Current assignee: T I FORDS Ltd
Priority date: 1979-10-19
Filing date: 1979-10-19
Publication date: 1981-05-13
Also published as: GB2061491B

Abstract

The invention relates to apparatus for and a method of detecting chipped necks of glass bottles, for receiving crown caps. Light beam 1 is directed to impinge upon a region of neck N of a bottle to produce a well defined emergent beam. If the bottle is perfect, the beam is concentrated along a path to impinge on detector D. If the neck is chipped, the beam is deflected and does not impinge on the detector. The intensity detected light is measured. A defective bottle is indicated if the measured intensity is below a threshold level. <IMAGE>

Description

SPECIFICATION Bottle Inspection Method and Apparatus The present invention relates to a method of and apparatus for bottle inspection apparatus, particularly for detecting chipped necks of glass bottles adapted to be closed by a crown cap. If defective bottles are not rejected before filling with a beverage and capping, various problems can occur ranging from loss of carbonation to glass contamination in the beverage.

The present invention has for its object to provide a method and apparatus which can detect a chip in the neck finish of a bottle at a rate which can be integrated into existing commercial bottle inspection apparatus for detecting dirt or foreign bodies in a bottle and which can carry out the inspection operation at a rate up to 750 bottles per minute or more.

Several proposals have been made for detecting chips in bottle necks. Examples of such detectors are described in British Specifications Nos. 1,185,889; 1,196,277; 1,286,665; 1,290,078; 1,418,727; 1,418,728; 1,478,663; 1,494,426; 1,530,723 and 2,003,268.

The method and apparatus according to the invention.like the prior proposals, uses the optical properties of glass for detecting a defective bottle.

However, instead of measuring radiation reflected from the glass of the bottle neck, the present invention measures radiation passing through the glass and emerging in a well-defined beam.

In order that the invention may be more clearly understood, reference will now be made to the accompanying drawings, in which: Figs. 1 and 2 are diagrams illustrating light paths through a bottle neck which provide welldefined emergent beams, Fig. 3 is a vertical section through the centre of one embodiment of measuring head according to the invention, Fig. 4 is a horizontal-section through the measuring head taken in the line IV-lV in Fig. 3, and Fig. 5 is a diagram of the detector electronic circuit.

Fig. 1 illustrates a portion of the neck N of a glass bottle having a shoulder formation A-B for receiving a crown cap. The light beams 1 and 2 indicate two possible light paths which provide well-defined emergent beams which can be used for carrying out the invention. Light path 1 which impinges on the region of the neck between the points A and B emerges as an almost horizontal well defined beam as shown in Fig. 1. If, however, the portion of the region of the neck between points A and B is missing, then the light emerges in a different direction as shown in Fig. 2.

Likewise, light path 2 emerges from an unchipped neck in a well-defined beam inclined at a longer angle to the horizontal, that direction changing if the neck is chipped. Beams 1 and 2 follow different paths through the glass and therefore enable inspection of different regions of the bottle neck.

Herein the invention will be further described in relation to apparatus making use of light path 1.

In the inspection apparatus a light detector D is positioned as shown in Fig. 1 to be impinged upon by the emergent beam from a perfect bottle.

Upon inspecting a bottle of which the region of the neck between the points A and B is missing, the beam emerges in a different direction as shown in Fig. 2 and the detector D registers a low light intensity.

In order to inspect the whole bottle neck circumference without rotating the bottle, a plurality of light source and detector pairs is mounted in a detector head as indicated in Figs. 3 and 4. Twelve pairs are shown in this embodiment.

The head is formed with a gap to allow the bottle neck to pass through the head in the direction indicated by the arrow in Fig. 4. The detectors D are arranged in the head in positions substantially level with the region A-B of the neck. The light sources L are mounted in the head so as to be inclined and directed towards the neck region A-B along the path 1 as shown in Fig. 1.

All of the light sources and detectors (except for the four detectors D1, D2, D3, D4 and their corresponding light sources) are arranged radially with respect to the bottle when in the central position of the head.

The four detectors D1 to D4 are arranged nonradially in order to leave room for the bottle to pass through the measuring head while maintaining equal spacing of measuring positions.

A bottle is failed if any detector registers a light intensity below a threshold level. The threshold level itself will be based on the average response of all the detectors in order to compensate for differences in optical transmission.

Variations in bottle height and colour are thereby compensated enabling inspection of clear and coloured bottles without adjustment to the apparatus.

As shown in Fig. 5 the output of each detector is amplified and the outputs Vt, V2, etc. of all the amplifiers Al, A2, etc. are averaged in a summing amplifier SA. A potentiometer P 1 is used to generate a threshold proportional to the average detector output and each amplified output is compared to this threshold in respective comparators C1, C2, etc. A 'high' output from any one or more of these comparators indicates a faulty bottle.

In general, only one or at most a few detectors will be effected by a defect and, whilst the signal level from these detectors changes a large amount, the average response, and therefore the threshold, is scarcely affected. It is however possible for the entire neck region to be missing and in order to ensure reliable rejection of such bottles a second, fixed threshold, set at a low level by a potentiometer, is used. Again, the amplified detector outputs are each compared to the threshold and a 'high' output from one or more comparators C'1, C'2, etc. indicates a faulty bottle.

The sources and detectors are continuously energized but a fail signal is only routed to the reject mechanism of the machine if it occurs while a bottle is in the measuring position. The presence of a bottle at the measuring position is detected by suitable means and allows any reject signal produced when a bottle is present to pass to the reject memory.

In the embodiment illustrated, the energizing voltage for the sources is d.c. Alternatively, however, an a.c. supply could be used, together with a.c. coupling between the detectors and their amplifiers. This would give improved performance at the low signal levels encountered with some highly absorbing coloured bottles since the effects of d.c. offsets caused, for example, by amplifier drift would be eliminated. Furthermore, phase discrimination could be used to eliminate any "cross-talk" between different source/detector pairs.

Claims

1. Apparatus for detecting defective neck portions of glass bottles adapted to be closed by a crown cap, in which the bottles are moved in single file through an inspection station with the crown neck portions of the bottles substantially in a common plane, characterized by an emitter for directing a beam of radiant energy to impinge upon and pass through the glass at a region of the neck portions which provides, in the case of a perfect neck portion, a well-defined emergent beam which is concentrated along a predetermined path, a detector positioned on said path to be impinged upon by the emergent beam from a perfect neck portion, and means for measuring the intensity of the radiant energy impinging upon the detector whereby a bottle having a defective neck portion in the region where the beam passes therethrough produces a deflection of the emergent beam and a reduction in the intensity of the radiant energy which impinges upon the detector.

2. Apparatus according to claim 1, characterized by a plurality of pairs of emitters and detectors, the emitters directing their radiant energy through different regions respectively of a neck portion being inspected to produce a corresponding plurality of said well-defined emergent beams concentrated, when the neck portion is perfect, along respective predetermined paths on which the respective paired detectors are positioned, said detectors being associated with means for measuring the intensities of the radiant energy impinging on the respective detectors and means for producing a reject signal when the intensity of the radiation impinging on any detector is below a threshold level.

3. Apparatus according to claim 2, characterized by some of said pairs of emitters and detectors being arranged radially with respect to the neck portion being inspected and some other pairs are arranged nonradially, whereby the different regions of the neck portion through which the emitters respectively direct their radiant energy are substantially equally spaced around the neck portion.

4. Apparatus according to claim 2 or 3, characterized by means for summing amplifier connected to produce an output which is the average of the outputs of the respective detectors, a plurality of comparators corresponding to the number of detectors, and means for feeding to each said comparator the output from a respective detector for comparison with a threshold value derived from the output of the summing amplifier, thereby to produce comparator outputs indicating whether or not the corresponding detector has detected a defect in the neck portion.

5. Apparatus according to claim 4, characterized by a further plurality of comparators corresponding in number to the detectors, and means for feeding to each said further comparator the output from a respective detector for comparison with a fixed threshold value which is lower than the threshold value derived from the output of the summing amplifier.

6. Apparatus according to claim 2, 3, 4 or 5, characterized by the emitters directing their radiation simultaneously onto the neck portion being inspected.

7. Apparatus according to any preceding claim, characterized by the or each emitter emitting radiant energy in the region of visible or invisible light.

8. Apparatus according to any preceding claim, characterized by the or each emitter being located above the top of the neck portion being inspected and arranged to direct its radiation on to the neck portion in a direction such that the refracted emergent beam, when the neck portion is perfect, is directed along a substantially horizontal path.

9. Apparatus according to any preceding claim, characterized by the or each emitter and detector being continuously energized during inspection of a plurality of bottles, means being provided for detecting the presence of a bottle in the inspection station and allowing any reject signal produced when a bottle is present to pass to a reject memory.

10. Apparatus for detecting defective neck portions of glass bottles adapted to be closed by a crown cap, substantially as hereinbefore described.

11. Method of inspecting translucent bottles having neck portions adapted to be closed by a crown cap in order to detect defective neck portions, characterized by directing a beam of radiant energy through a region of the neck portion which produces a well-defined emergent beam which is concentrated along a predetermined path when the neck portion is perfect and is deflected from said path when the neck portion is defective, measuring the intensity of the emergent radiant energy directed along said predetermined path, and producing a reject signal when the measured intensity is below threshold level.

12. Method according to claim 11, characterized by directing a plurality of beams of radiant energy through different regions respectively of a neck portion being inspected to produce a corresponding plurality of said welldefined emergent beams concentrated along respective predetermined paths when the neck portion is perfect, measuring the intensities of the radiant energy directed along said respective paths, and producing a reject signal when the measured intensity along any of said paths is below a threshold level.

13. Method according to claim 12, characterized by comparing the measured intensities in the respective paths with a threshold derived from the average of the measured intensities in each of the paths, and producing a reject signal in dependence upon the results of said comparisons.

14. Method according to claim 12 or 13, characterized by also producing a reject signal in dependence upon the results of comparing said respective measured intensities with a fixed threshold.

1 5. Method according to any one of claims 11 to 14, characterized in that the radiant energy comprises visible or invisible light radiation.

16. Method according to any one of claims 11 to 15, characterized by directing the radiant energy from above the level of the top of the neck portion to impinge upon the neck portion in a direction or directions such that the or each refracted emergent beam, when the neck portion is perfect, is directed along a substantially horizontal path.

17. The method of detecting defective neck portions of translucent bottles adapted to be closed by a crown cap, substantially as hereinbefore described.