The invention relates generally to methods of non-destructive analysis. More particularly, the invention relates to an inspection method and device for quickly and non-destructively analyzing a container material for the presence of leaks.
Closed packages are used to package a wide variety of products, including foods, condiments, and medicines, as well as other products such as batteries, and cosmetics. These packages function to contain and protect the products contained within them. They may also function as barriers to elements that might degrade, corrode, or otherwise compromise the quality of the product, including, for example, moisture, bacteria and other undesired microorganisms, and oxygen. The integrity of the packaging material is therefore of utmost importance, particularly when the contents are medicines. A liquid medicine contained within a package which has defects may slowly leak out undetected, resulting in a lower effective dosage. The medicine may become contaminated with a microbial agent, thereby compromising the health of the individual to whom the medicine is administered.
Various methods have been developed to detect leaks in packaging material. These methods include line scan camera surface inspection systems, LED systems, hydrocarbon leak detection systems, and SF6 detection systems. See, for example, U.S. Pat. Nos. 5,361,626; 5,499,529; 5,363,968; and 5,969,373. Other methods involve testing for flow of a gas such as CO2 or helium leaking from a package. Demorest et al. (1992) J. Plastic Film and Sheeting 8:109-123. These methods generally involve introduction of a gas into the package headspace by flushing the package and its contents prior to sealing; forcing the gas into the package after sealing with a pressurized bomb; or providing the gas as a normal component of the product or package. Typically, once the gas is introduced, a pressure differential is induced across the packaging material, and any gas leaks detected. Detection is generally accomplished by infrared detection device or by mass spectrometer. The detection limits of these methods are relatively high, however, and as a consequence, leaks may go undetected.
There is a need in the art for a rapid, sensitive, and effective inspection method which can analyze packaging material for defects before it is filled with a product.
The present invention provides methods and devices for detecting imperfections in a packaging material prior to filling with a product to be packaged. Packaging materials formed into a packaging unit are inspected or non-destructively analyzed by (1) applying a gas simultaneously with or immediately after forming the packaging unit; (2) detecting any gas which has passed through the packaging material of the packaging unit; and (3) analyzing the detected gas in a manner which makes it possible to quickly determine whether the packaging unit should xe2x80x9cpassxe2x80x9d inspection based on criteria such as amount of gas measured.
In some embodiments, the packaging unit is a blister, and is formed by mechanical deformation with a piston. The piston has a lumen extending through the piston, through which a gas is forced.
Detection is carried out by a detection means. In some embodiments, the detection means is a thermal conductivity sensor. The detection means can detect leaks as small as about 1 xcexcm to about 0.1 xcexcm in the packaging material.
The detection means may be part of an inspection system, comprising a detection device, and a signal means for transmitting a signal to a filling means, which may be part of a manufacturing system. The signal means transmits either a positive or a negative signal to the filling means. A positive signal is generated in the event that no gas above detection limits is detected, and the filling means fills the packaging unit with product. A negative signal is generated in the event that gas is detected, and the filling means skips the defective packaging unit. Since containers with flaws are not filled with product, there is less product waste. Furthermore, since containers with flaws are not filled with product, the probability that the product will become contaminated with microorganisms, or will become chemically and/or physically altered before dispensing to a user is reduced.
An advantage provided by the inspection system of the present invention is that it can be integrated into a manufacturing system for the manufacture of containers, such as blister packs. Integration of manufacturing and inspection reduces inspection time.
These and other aspects, objects, advantages and features of the present invention will become apparent to those skilled in the art upon reading this disclosure and reviewing the drawings forming a part hereof.