WO2001084975A2

WO2001084975A2 - Method and apparatus for detecting ophthalmic lenses in packages

Info

Publication number: WO2001084975A2
Application number: PCT/US2001/014056
Authority: WO
Inventors: Dharmendra Jani; Frank D. Tasber; Linda Mosack
Original assignee: Bausch & Lomb Incorporated
Priority date: 2000-05-09
Filing date: 2001-05-01
Publication date: 2001-11-15
Also published as: WO2001084975A3; AU2001261111A1

Abstract

A method and apparatus for detecting under- or over-filling of lenses in packages where ultrasonic energy is directed to the package.

Description

METHOD OF DETECTING LENSES

Background of the Invention

A conventional method of packaging ophthalmic lenses, such as contact lenses, is in so-called blister packages. Such packages include a recess designed to hold an individual lens, usually in a saline solution in the case of soft hydrogel lenses. The blister packages are then enclosed and sealed with lidstock, the lidstock conventionally being a metallic laminate. In an automated process for packaging contact lenses, it sometimes occurs that a recess will be incorrectly filled, usually by two lenses or none, rather than the intended single lens. Each incorrectly filled package escaping detection can represent wasted capacity, material or labor, or lost customer goodwill. Summary of the Invention

The invention provides a method for confirming that an individual contact lens is present in a recess of a blister package, or determining if there is an excess or a deficiency in the number of lenses in the package. The method involves ahgning a package with an ultrasonic detection system and confirming the presence or absence of a lens in the package. According to preferred embodiments, the ultrasonic detection system comprises a source of ultrasonic waves directed towards contents of the package and a receiver to detect at least a portion of the ultrasonic waves reflected from or transmitted through the package contents. The source of the ultrasonic waves may be a transducer acoustically coupled to the package contents, where the ultrasonic waves are directed from the transducer to the package contents, and reflected to the same transducer in connection with the receiver. According to other preferred embodiments, the lens is a contact lens and the package is a blister package having a recess for holding an individual contact lens in an aqueous packaging solution. Brief Description of the Drawings

FIG. 1 is a perspective view of a lens blister package that includes a recess for holding a contact lens and packaging solution.

FIG.2 is a schematic, partial cross-sectional view of a blister package and an apparatus according to a first embodiment of the invention.

FIG. 3 a illustrates an amplitude waveform for the blister package in FIG. 2 containing packaging solution but no lens. FIG. 3b illustrates the waveform of FIG. 3a after performing reference subtraction.

FIG. 4a is a schematic, partial cross-sectional view of a blister package and an apparatus according to the embodiment of the invention, where the package includes a single lens in a concave-down orientation.

FIG. 4b illustrates a waveform for the blister package in FIG. 4a.

FIG. 4c illustrates the Fast Fourier Transform FFT) of the waveform of FIG. 4b.

FIG. 5a is a schematic, partial cross-sectional view of a blister package and an apparatus according to the embodiment of the invention, where the package includes a single lens in a concave-up orientation.

FIG. 5b illustrates a waveform for the blister package in FIG. 5a. .

FIG. 5c illustrates the Fast Fourier Transform of the waveform of FIG. 5b.

FIG. 6a is a schematic, partial cross-sectional view of a blister package and an apparatus according to the embodiment of the invention, where the package includes two superimposed lenses in a concave-down orientation.

FIG. 6b illustrates a waveform for the blister package in FIG. 6a.

FIG. 6c illustrates the Fast Fourier Transform of the waveform of FIG. 6b.

FIG. 7a is a schematic, partial cross-sectional view of a blister package and an apparatus according to the embodiment of the invention, where the package includes two superimposed lenses in a concave-up orientation.

FIG. 7b illustrates a waveform for the blister package in FIG. 7a.

FIG. 7c illustrates the Fast Fourier Transform of the waveform of FIG. 7b.

FIG. 8a is a schematic, partial cross-sectional view of a blister package and an apparatus according to the embodiment of the invention, where the package includes two superimposed lenses in a concave-up orientation and one lens in a concave-down orientation.

FIG. 8b illustrates a waveform for the blister package in FIG. 8a.

FIG. 8c illustrates the Fast Fourier Transform of the waveform of FIG. 8b.

FIGs. 9, 10 and 11 are schematic, partial cross-sectional views of a blister package and an apparatus according to additional embodiments of the invention. Detailed Description of the Preferred Embodiment

FIG. 1 illustrates a blister package for an ophthalmic lens such as a contact lens. In the illustrated embodiment, the package 10 includes a recess 12 for holding an individual contact lens 14. Recess 12 terminates at surface 16, and typically a metallic lidstock 18 is sealed to surface 16 so as to sealingly encase recess 12 and enclose package 10. It is conventional for such packages to contain a packaging solution 19, such as saline solution, that is sealed in recess 12 along with the lens 14. Contact lens blister packages are typically made of various grades of a plastic, including polyolefins such as polypropylene or polyethylene.

An occasional problem in manufacturing contact lenses is that a lens may be missing from the blister package 10, or that two lenses - "twins" - may be dispensed into the recess 12 in error. The absence of a lens or the occurrence of twins is more likely to go unnoticed in an automated or semi-automated system where an operator is not manually placing a lens in each package 10 immediately prior to the sealing of the package with lidstock.

FIG. 2 shows schematically an apparatus for detecting an excess or deficiency of lenses in the package 10. The apparatus includes a source of ultrasonic energy, which in the illustrated embodiment, is a transducer 20. For example, transducer 20 may be a piezoelectric transducer, where sound waves are generated by exciting the transducer with a voltage spike. In the illustrated embodiment, transducer 20 is in electrical connection with pulser/receiver 21, pulser/receiver 21 providing the electrical input for transducer 20 to generate high frequency sound waves. Such apparatus are commercially available, for example, a 10-MHz transducer (available from Panametrics, Inc„ Waltham, Massachusetts, USA) and a 35-MHz pulser/receiver (available from JSR Ultrasonics, Inc., Rochester, New York, USA).

Transducer 20 is acoustically coupled to the contents of package 20. In order to ensure an adequate acoustical connection to package 10, a coupling film 22 may be introduced between the transducer 20 and the package 10. The coupling film may be a "wet couplant" having the form of a liquid or gel, such as an aqueous-based gel containing glycerin. Alternately, the coupling film may be a "dry couplant" having the form of a polymer film (such as the film available under the tradename Aqualene from Utex Scientific Instruments, Inc., Mississauga, Ontario, Canada). In the illustrated embodiment, transducer 20 generates ultrasonic energy, in the form of sound waves, that is directed towards the contents of package 10, and reflected back to the transducer. Generally, any discontinuity in the package contents will result in a reflection of the waves accompanied by a phase reversal. In the illustrated embodiment, the reflected signal is received at the pulser/receiver 21 from transducer 20. The strength of the reflected signal is represented by the amplitude of the waveform. This reflected signal is analyzed by controller 23 in electrical connection with the receiver. Optionally, controller 23 may also amplify the signal reflected to and received by the receiver. Controller 23 may include a data acquisition system, such as the Windows-based system available under the tradename Winspect from Utex Scientific Instruments, Inc.

FIG. 3a illustrates a sample waveform obtained from a package 10 including saline solution 19 but no contact lens, as in the apparatus set-up illustrated in FIG. 2. The x-axis in FIG. 3 a represents the temporal locations of the waveforms, expressed in microseconds. The y-axis represents the amplitude of the reflected waveform The relatively high amplitude of reflected waveforms at the left end of the x-axis are attributed to the proximity of the transducer to the bottom of the package 10; the walls of the package 10 and the solution 19 contained therein also contribute to certain levels of background "noise". In other words, most of the ultrasonic energy is reflected back at the transducer/package interface which is indicated by the high amplitude of the reflective waveform. However, by employing controller 23 to perform reference subtraction on the waveform to eliminate "noise" attributed to the package and solution (also referred to as signal averaging), a reference waveform may be obtained as shown in FIG. 3b.

FIG. 4a illustrates an apparatus set-up similar to FIG. 2, but in FIG. 4a a single contact lens, oriented in a concave-side-down orientation, has been inserted in the package. FIG. 4b illustrates a sample waveform obtained from the apparatus set-up of FIG. 4a, after performing the aforementioned subtraction technique to eliminate expected noise attributed to the package and solution. In FIG. 4b, the x-axis represents the temporal locations of the reflected ultrasonic signal, and the y-axis represents the amplitudes of the reflected signals. The signal in the 6-7 microsecond range of FIG. 4b is attributed to the single lens in FIG. 4a. Optionally, the signal obtained as in FIG. 4b may be amplified and/or integrated to yield a best-fit signal such as shown in FIG. 4c.

FIG. 5a illustrates an apparatus set-up similar to FIG. 2 and FIG. 4a, but in FIG.

5a the package includes a single contact lens, oriented in a concave-side-up orientation. FIG. 5b illustrates a sample waveform obtained from the apparatus set-up of FIG. 5 a, after performing the aforementioned subtraction technique to eliminate expected noise attributed to the package. The signal at the 2 microsecond portion of FIG. 5b is attributed to the single lens in FIG. 5a. In FIG. 5c, the signal obtained in FIG. 5b has been integrated to yield a best-fit signal.

Each of FIGs. 6a, 7a and 8a illustrates an apparatus set-up similar to FIGs. 4a and 5a, but involving different orientations of lenses. In FIG. 6a, two lenses 14 are superimposed in a concave-side down orientation. In FIG. 7a, two lenses 14 are superimposed in a concave-side up orientation. In FIG 8a, two lenses 14 are superimposed in a concave-up orientation and one separate lens is oriented in a concave- down position. FIGs. 6b, 7b and 8b illustrate a sample waveform obtained from the respective apparatus set-ups after performing the aforementioned subtraction technique, and FIGs. 6c, 7c and 8c illustrate best-fit signals integrated from the signals of FIGs. 6b, 7b and 8b, respectively. It can be seen that the signals obtained from the package contents of FIGs. 6a, 7a and 8a are unique from the signals obtained from the aforementioned package contents in FIGs. 4a and 5a.

It is noteworthy that even when two lenses were closely nested together, as in FIGs. 6a and 6b, distinct signals were obtained by the method of this invention that permitted distinguishing this arrangement from packages containing only a single lens. In contrast, contact lenses nested or "stuck" together in this manner are generally difficult to inspect visually.

For an in-line package detection system, at a first station, each package, prior to the intended insertion of a single lens in the package, may be subjected to the ultrasomc energy and reference subtraction is performed on the waveform signal. At a downstream station, after the intended insertion of a single lens in the package, the package is again subjected to the ultrasonic energy and this final observed signal can be compared with the aforementioned signals obtained as in FIGs. 3b, 4b, 5b, etc. Alternately, this observed signal may be amplified and/or integrated as in FIG. 4c, 5c, 6c, etc. By correlating the ultrasonic wave signals in this manner, a determination can be made by an operator, or by automatic means if the controller includes a correlating algorithm, that the package contains one contact lens as intended, or is missing a lens, or contains more than one lens. In the embodiments of FIGs. 1 to 8 discussed above, the packages were evaluated prior to placing lidstock 18 on package 10. Thus, packages that pass the evaluation criteria, i.e., packages that contain a single contact lens, may be transferred to a station for placement of lidstock thereon. Packages that do not pass the evaluation criteria, i.e., packages that contain no contact lens or more than one lens, may be discarded or redirected for adding a lens thereto or redirected for manual inspection.

FIG. 9 illustrates an alternate apparatus of this invention. In this embodiment, an array of transducers 20 are acoustically connected with the bottom of package 10, with each transducer connected to pulser/receiver 21. This arrangement may yield a more definitive signal in certain circumstances, such as when two lenses are located at different portions of the package, as in FIG. 9 or FIG. 8a. Also, FIG. 9 illustrates evaluation of packages after lidstock 18 has been placed on the package. FIG. 10 illustrates another alternate embodiment, where a transducer 20 is acoustically connected with the lidstock 18 of package 10. For these embodiments, it is preferred that reference subtraction is performed to eliminate "noise" attributed to the package, lidstock and solution.

FIG. 11 illustrates another embodiment, where a transducer 20 (or array of transducers, if desired) is partially immersed in solution 19. In other words, the transducer is in direct acoustical connection with the solution instead of the package 10. This approach avoids the need to form the direct acoustical connection with the package 10. For contact lens applications, it is generally required that the package contents are sterile. Accordingly, for this approach, it may be desirable to sterilize the package contents, for example by autoclaving, after adding lidstock to the package, rather than prior to the contact of the solution with the transducer, to minimize the risk of contamination of the solution by direct contact with the transducer. Alternately, the transducer 20 in the apparatus of FIG. 11 may have the form of an array of transducers, as in FIG. 9, where the individual transducers are partially immersed in the solution 19.

As a further alternative, a color scale may be assigned based on the levels of the wave reflected from the package contents. For example, the presence of a lens or lenses changes the amplitude of the reflected wave, and by assigning different colors to different reflected wave amplitudes, a color-graduated image of the package contents may be captured and displayed on a screen for viewing by an operator. While the invention has been described in connection with various preferred embodiments, various other alternate embodiments may be made without departing from the spirit of the invention and the scope of the appended claims. Such variations will be evident to a person of ordinary skill in the art.

Claims

What is claimed:

1. A method comprising aligning an ophthalmic lens package with an ultrasonic detection system and recognizing the presence or absence of a lens in the package.

2. The method of claim 1 , further comprising recognizing an excess number of lenses in the package.

3. The method of claim 1 , wherein the package comprises a recess for holding an individual contact lens, said recess containing a packaging solution for the lens.

4. The method of claim 1 wherein the ultrasomc detection system comprises a source of ultrasonic waves directed towards contents of the package and a receiver to detect at least a portion of the ultrasonic waves reflected from or transmitted through the package contents.

5. The method of claim 4, wherein the source of ultrasonic waves is a transducer acoustically coupled to the package contents.

6. The method of claim 5, wherein the ultrasonic waves are directed from the transducer to the package contents, and reflected to the same transducer in connection with the receiver.

7. The method of claim 5, wherein the transducer is brought into direct acoustical connection with the package.

8. The method of claim 4, wherein ultrasonic waves received at the receiver are correlated to confirm that a single lens is present in the package, or to determine that the lens is missing, or to determine that an excess number of lenses are present.

9. The method of claim 8, wherein the receiver transfers a signal to a controller where the signal is analyzed and compared with reference data stored in the controller.

10. An apparatus comprising an ultrasonic detection system acoustically coupled to contents of an ophthalmic lens package, the ultrasonic detection system detecting the presence or absence of an ophthalmic lens in the package.

11. The apparatus of claim 10, wherein the detection system further detects an excess number of lenses in the package.

12. The apparatus of claim 10, wherein the ultrasonic detection system comprises a source of ultrasonic waves directed to the package contents and a receiver to detect at least a portion of the ultrasonic waves reflected from or transmitted through the package contents.

13. The apparatus of claim 12, wherein the source of ultrasonic waves is a transducer acoustically coupled to the package contents.

14. The apparatus of claim 13, wherein the ultrasonic waves are directed from the transducer to the package contents, and reflected to the same transducer in connection with the receiver.

15. The apparatus of claim 14, wherein ultrasonic waves received at the receiver are correlated to confirm that a single lens is present in the package, or to determine that the lens is missing, or to determine that an excess number of lenses are present.

16. The apparatus of claim 12, comprising an array of transducers acoustically coupled to the package contents.

17. The apparatus of claim 10, wherein the package comprises a recess to hold an individual contact lens and packaging solution.