Method and apparatus for inspecting liquids in transparent containers

A system for inspecting a liquid filled container for particulate contamination comprising:

• a. a source of radiation directed at said liquid filled container,
• b. means to rotate said liquid about an axis while said container is held stationary at an inspection station,
• c. means to dissect the article image into a plurality of columns which extend from the bottom of the container through the top of the liquid meniscus,
• d. sensing means to separately monitor each of said columns to detect changes in illumination,
• e. means to translate said changes in illumination into voltage signals,
• f. means to form a composite signal of all of said voltage signals.
• g. means to accept or reject said liquid filled container based upon a comparison of said composite signal to a standard reference signal.

A method for inspecting the meniscus of a rotating liquid in a transparent stationary container for particulate contamination comprising the steps of:

• a. illuminating said meniscus,
• b. monitoring said meniscus at two portions in which the voltage signals generated by the meniscus decay would be substantially similar for changes in illumination due to moving particulate matter and meniscus decay,
• c. electronically translating each of said changes in illumination into a voltage signal,
• d. substantially eliminating the voltage signals due to the meniscus decay by electronically subtracting the voltage signals originating in each of said two portions,
• e. forming a composite signal of all of said moving particulate matter voltage signals,
• f. comparing said composite signal to a standard reference signal and based thereon accepting or rejecting said liquid filled container for particulate contamination.

A method for inspecting a liquid filled transparent container for foreign particles in the liquid, said method comprising the steps of:

• a. placing the article at an inspection station,
• b. rotating said liquid about an axis below the speed that will cause cavitation and bubbling of the liquid while holding said container stationary,
• c. illuminating said article,
• d. dissecting said rotating liquid volume into a meniscus volume image and a sub-meniscus volume image,
• e. monitoring said sub-meniscus volume image for changes in illumination which are indicative of moving particulate matter,
• f. monitoring said meniscus volume image at two portions, in which the voltage signals generated by the meniscus decay would be substantially similar, for changes in illumination which are indicative of moving particulate matter and the meniscus decay of the rotating liquid,
• g. electronically translating each of said changes in illumination into voltage signals,
• h. substantially eliminating the voltage signals due to the meniscus decay by electronically subtracting the voltage signals originating in each of said two portions,
• i. forming a composite signal of all of the moving particulate matter signals from said sub-meniscus volume and said meniscus volume,
• j. comparing said composite signal to a standard reference signal and based thereon accepting or rejecting said liquid filled container for particulate contamination.

A system for inspecting a liquid filled container for particulate contamination comprising:

• a. a source of radiation directed at said liquid filled container,
• b. means to rotate said liquid about an axis while said container is held stationary at an inspection station,
• c. means to dissect the image of said rotating liquid into a meniscus volume image and a sub-meniscus volume image,
• d. means to monitor said sub-meniscus volume image for changes in illumination due to moving particulate matter,
• e. means to monitor said meniscus volume image at two portions, in which the voltage signals generated by the meniscus decay would be substantially similar, for changes in illumination due to moving particulate matter and the meniscus decay of the rotating liquid,
• f. means to electronically translate said changes in illumination into voltage signals,
• g. means to substantially eliminate the voltage signals due to the meniscus decay by electronically subtracting the voltage signals originating in each of said two portions,
• h. means to form a composite voltage signal of all of said moving particulate matter voltage signals,
• i. means to compare said composite signal to a standard reference signal, and means to accept or reject said container based thereon.

A system for inspecting in relative size particulate matter in a liquid comprising:

• a. a light source,
• b. means to maintain said light source at a constant intensity,
• c. means to rotate said liquid about an axis while said container is held stationary at an inspection station,
• d. sensing means to monitor only changes in the illumination value of selected portions of said liquid filled container and to translate said changes in illumination into voltage signals,
• e. means to form a composite signal of all of said voltage signals,
• f. means to accept or reject said liquid filled container based upon a comparison of said composite signal to a standard reference signal,
• whereby the intensity of the illumination value reflected by particles of constant reflectivity are always proportionate to the cross sectional area of the particles viewed.

A method for inspecting illuminated articles wherein each of said articles comprise a liquid-filled transparent container, that may have a multiplicity of specular reflections on or in itself, which liquid is to be inspected for the presence of foreign particles, said method comprising the steps of:

• a. placing the article at an inspection station having associated article illuminating means,
• b. rotating said article about an axis to cause any of said foreign particles to rotate in planes substantially parallel to said axis of rotation,
• c. while the illuminated liquid and any particles therein continue to swirl, dissecting the article image into a plurality of columns each of which intersect all of said planes at more than one point,
• d. continuously monitoring with separate sensing means each of said columns to detect changes in illumination,
• e. electronically translating said changes in illumination into voltage signals,
• f. forming a composite signal of said voltage signals,
• g. comparing said composite signal to a standard reference signal and based thereon accepting or rejecting said article for particulate contamination;
• whereby the image of particulate matter which moves past a column with a saturated sensing means will be detected as it passes through a column with an unsaturated sensing means.

A method for inspecting a sub-meniscus volume of a rotating liquid within a stationary transparent container to detect particulate contamination, said method comprising the steps of:

• a. placing the article at an inspection station,
• b. rotating said liquid about an axis while holding said container stationary,
• c. illuminating said article,
• d. dissecting said sub-meniscus volume image into a plurality of columns each of which extend from the bottom of the container through the top of said sub-meniscus volume,
• e. continuously monitoring with separate sensing means each of said columns to detect changes in illumination,
• f. electronically translating said changes in illumination into voltage signals,
• g. forming a composite signal of said voltage signals,
• h. comparing said composite signal to a standard reference signal and based thereon accepting or rejecting said article for particulate contamination;
• whereby the image of particulate matter which moves past a column with a saturated sensing means will be detected as it passes through a column with an unsaturated sensing means.