Method and apparatus for inspecting glass containers

This invention relates to method and apparatus for inspecting glass containers and other types of containers having transparent or translucent sidewalls for defects, and especially to inspecting the finish portion of glass containers for defects such as horizontal checks. The entire finish portion is illuminated by diffused light and the check-type defects reflect light upwardly into an Erfle eyepiece which is then imaged onto a matrix-type light sensor.

This invention relates to inspecting glass containers and other types of 
containers having transparent or translucent sidewalls for defects, and 
especially to inspecting glass containers for defects such as horizontal 
checks in the finish portion thereof. 
BACKGROUND OF THE INVENTION 
In the manufacture of glass containers, a defect that is sometimes found 
which is difficult to detect comprises a generally horizontal check or 
mirror-like flaw in the neck or finish portion of the container. It is 
essential that such defects or flaws be detected even though they be few 
in number, with respect to the total number of containers being 
manufactured. 
The prior art has employed various types of inspection devices primarily 
relying on illuminating the defect and then reading the presence of 
reflected light emitted by the defect. The following U.S. patents all 
relate to such devices which are satisfactory to a greater or lesser 
degree in detecting defects, primarily to directing and reading the 
scattered light by altogether different forms of apparatus. The patents 
are: 
U.S. Pat. No. 3,349,906--Calhoun et al. 
U.S. Pat. No. 3,834,429--Schulz 
U.S. Pat. No. 4,140,901--Fischer et al. 
U.S. Pat. No. 4,213,042--Beach et al. 
All of the aforesaid patents involve methods and apparatus which are 
substantially different and less effective than the present invention. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide method and apparatus 
for quickly inspecting the finish portion of a hollow, transparent 
container for horizontal checks on the surface or buried in the walls 
thereof and rejecting those containers having such defects or flaws. 
It is a further object of the present invention to provide such method and 
apparatus wherein glass containers can be inspected without rotation 
immediately after forming and annealing while they are relatively cool or 
at ambient temperature, following such operations. 
Another object of the invention is to provide such method and apparatus 
which is relatively simple and economical whereby the finish area of 
containers can be inspected without rotation in a very expedient manner. 
Generally, the invention comprises moving the hollow containers 
successively through an inspection station, momentarily interrupting the 
lateral movement of each container and retaining same stationarily upright 
at the inspection station, directing a concentrated source of radiant 
energy to which the container is transparent downwardly through the 
complete region of the finish portion to thereby illuminate the sidewalls 
thereof, and causing a portion of the light to be redirected upwardly 
axially by any existent checks. The redirected light is imaged onto a 
light-sensitive detector, such as a video camera stationarily mounted 
axially facing downwardly and adjacent to the container upper lip area. 
The redirected sensed light is detected by the sensor during stationary, 
non-rotational retention of the container at the inspection station and 
the sensor produces a reject signal for subsequent rejection of the flawed 
container.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring to the drawings, the containers 10 are adapted to be moved 
through an inspection station on a rotary inspection machine, such as by a 
starwheel mechanism, as is known in the art. The rotary inspection machine 
(not shown), and specifically its starwheel mechanism, moves each 
container 10 in upright position to the inspection station, as shown in 
FIG. 1. The container is preferably inspected while being moved laterally 
in-line without stoppage. However, its lateral movement may also be 
interrupted momentarily by stopping the starwheel for a required brief 
inspection interval. Normally, the containers are newly-formed but not 
sufficiently hot to require special handling techniques or non-checking 
materials to handle the same. The inspection is preferably conducted 
immediately following the annealing procedure to remove inherent stresses 
from the containers and while they are at ambient temperature. 
When each container 10 is positioned at the inspection station, it is 
preferably resting upright on a non-rotatable disc or pad. With the 
container in proper position for inspection, a source of radiant energy 
such as provided by an incandescent source or flash lamp 12, in the form 
of an annular ring or circular tube, is mounted within a suitable hollow 
circular chamber 13. The lamp 12 is connected to a suitable power source 
such as a 110 V electrical line. A diffuser plate 14 in the form of a 
translucent circular disc is mounted beneath hollow chamber 13, with both 
the diffuser plate and the chamber having a central opening or aperture. 
The diffuser plate is mounted closely adjacent to and immediately over the 
finish portion 10a of the container in axial alignment therewith at the 
inspection station. The diffused light is transmitted into and through the 
finish portion 10a, the container being transparent to such transmitted 
light. 
The downwardly-directed diffused light passes into the interior portion of 
the container and brightly illuminates the same. If a defect or flaw, such 
as a horizontal check C is present in the finish of the container, a 
portion of the internally-transmitted light is redirected exteriorly 
upwardly through the central opening in diffuser plate 14 and chamber 13 
into an Erfle lens 15. The lens is mounted within an upper region of 
chamber 13 to gather the upwardly redirected and reflected light from the 
check C as shown in FIG. 3. The light sensor 16 such as a video camera is 
sensitive to the radiant energy emitted by the light source and reflected 
by the defect C. The lens 15 serves to gather and concentrate the 
reflected light in the light sensor 16 to increase its sensitivity. If a 
defect such as a check C is present, the redirected portion of the light 
is caused to pass upwardly through the container surface exteriorly and 
vertically to be collected by the lens system and be detected by the 
sensor. 
The sensor 16 comprising a video camera is preferably a video array camera. 
Such video camera is a matrix array of discrete light-sensitive diodes 
which view the container finish, such as a threaded bottle finish, in a 
horizontal direction. The diodes are sequentially electronically 
interrogated (scanned) to determine which diodes have seen an increase in 
light intensity which results in a greater output voltage from these 
diodes. One can then compare voltages from adjacent diodes or ratios of 
voltages to detect a bright signal and measure the intensity and location 
of the signal. The scan information is used to produce a reject signal. 
The reject signal serves to energize a reject mechanism mounted at a 
subsequent point along an off-loading conveyor which discharges the 
inspected containers. 
The circular lamp element provides 360.degree. illumination so that the 
container or bottle does not require rotation. The reflected light is 
gathered by an Erfle eyepiece (multi-element lens) which provides an 
extremely-wide field of view and excellent correction of all aberrations. 
The wide-angle field of view permits simultaneous imaging of the entire, 
nominally-cylindrical, wall of the finish portion of the container. Such 
system is known to provide excellent spherical and chromatic correction. 
Thus, the present invention provides an improved method and apparatus for 
inspecting the finish area of hollow transparent containers for horizontal 
checks or interior flaws. Such defects can be efficiently and expediously 
determined in glass containers whether they be formed of clear fling glass 
or colored glass. Since the containers need not be rotated, the inspection 
can be achieved in a small fraction of a second for each container. In 
addition, the technique is applicable to non-round containers which are 
mechanically difficult to rotate. Defects, whether they be relatively 
small or large, so long as they exhibit an appreciable horizontal 
component, can be detected by the present invention. The circular lighting 
element and diffuser serve to provide azimuthally symmetric illumination 
of the entire finish portion, with a large diversity of ray directions 
impinging upon the finish. The latter has the effect of ameliorating 
refractive effects of contour variations in the shape of the finish such 
as threads. In addition, the large diversity of light ray directions 
impinging upon the check permits the check to reflect light toward the 
detector for a large range of check orientations. 
The present invention provides a method and apparatus for detecting 
horizontal checks in the finish portion of transparent containers, 
wherever they may be located, by illuminating the finish from above. The 
primary purpose is to enhance the horizontal checks in the prescribed area 
of the container to allow their ready detection and subsequent rejection 
of the container by an independent device dedicated to horizontal check 
detection. This invention illuminates horizontal checks or vertical checks 
having a horizontal component and makes their detection readily possible. 
The present invention lends itself to application to existing inspection 
machines performing multiple inspecting functions at a series of 
sequential inspection stations mounted on a circular machine, for example. 
The apparatus of this invention may be mounted at one of such stations for 
horizontal check detection. 
Various modifications and other embodiments of the present invention may be 
resorted to within the spirit and scope of the appended claims.