Inspection systems and methods for blow-molded containers

• US 8,208,141 B2
• Filed: 03/09/2011
• Issued: 06/26/2012
• Est. Priority Date: 09/01/2006
• Status: Active Grant

• Current Assignee: Agr International, Inc.
• Original Assignee: Agr International, Inc.
• Inventors: Schmidt, William E., Wolfe, Georg V.
• Primary Examiner(s): Geisel, Kara E
• Application Number:
  US13/044,390
• Publication Number:
  US 20120018925A1
• Time in Patent Office: 475 Days
• Field of Search: 356/239.4, 356/402, 250/223.B, 264/408
• US Class Current: 356/402
• CPC Class Codes: G01B 11/06 for measuring thickness ; e.g. of sheet material thickness measurement by thermal means G01B21/085
• CPC Class Codes: G01B 11/0633 using one or more discrete wavelengths
• CPC Class Codes: G01B 11/245 using a plurality of fixed, simultaneously operating transducers G01B11/2408 - G01B11/2425, G01B11/255 take precedence
• CPC Class Codes: G01N 2021/3181 using LEDs
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/9081 Inspection especially designed for plastic containers, e.g. preforms

Abstract

Systems and methods for in-line inspection of plastic blow molded containers. The inspection system may comprise a plurality of emitter assemblies arranged in a vertical array. Each emitter assembly may cyclically emit light energy in at least two different narrow wavelength bands at a container as the container passes through an inspection area. The system may also comprise a plurality of broadband photodetectors arranged in a vertical array, each photodetector facing at least one of the emitter assemblies with the inspection area therebetween such that the photodetectors are capable of sensing light energy that passes through the container when it is in the inspection area. The system may also comprise a processor in communication with the photodetectors for determining a characteristic of the container based on signals from the photodetectors.

Claims

1. A system for measuring a property of a blow-molded container, the system comprising:

a plurality of emitters, wherein at least a first portion of the plurality of emitters is configured to emit light energy at a first wavelength band and at least a second portion of the plurality of emitters is configured to emit light energy at a second wavelength band as the container passes through an inspection area, wherein the plurality of emitters are configured such that emissions in the same wavelength band from spatially adjacent emitters are offset in time;

a plurality of detectors, wherein each of the plurality of detectors is aligned to receive light energy emitted by at least one of the plurality of emitters and is sensitive to light energy in the first wavelength band and in the second wavelength band; and

at least one processor in communication with the plurality of emitters and the plurality of detectors, wherein the at least one processor is programmed to;

receive from the plurality of detectors a first signal indicating light energy in the first wavelength band received by at least one of the plurality of detectors through the blow-molded container;

receive from the plurality of detectors a second signal indicating light energy in the second wavelength band received by at least one of the plurality of detectors through the blow-molded container; and

determine a characteristic of the blow-molded container considering the first signal and the second signal.

2. The system of claim 1, wherein all of the plurality of emitters are configured to alternately emit light energy at the first wavelength band and at the second wavelength band.

3. The system of claim 1, wherein light energy in the first wavelength band is at least partially absorbed by the blow-molded container, and wherein light energy in the second wavelength band is substantially transmitted by the blow-molded container.

4. The system of claim 1, wherein the first signal is indicative of light in the first wavelength band absorbed by the blow-molded container.

5. The system of claim 1, wherein the plurality of emitters are arranged vertically.

6. The system of claim 5, wherein the plurality of detectors are arranged vertically.

7. The system of claim 1, wherein the characteristic of the blow-molded container is a two-wall average thickness of the container.

8. The system of claim 1, wherein the characteristic of the blow-molded container is selected from the group consisting of mass and volume.

9. The system of claim 1, wherein each emitter comprises:

a first light source that emits light energy in the first wavelength band; and

a second light source that emits light energy in the second wavelength band.

10. The system of claim 1, wherein physically adjacent emitters of the plurality of emitters do not emit light energy simultaneously.

11. The system of claim 1, wherein the first wavelength band is around 1835 nm and the second wavelength band is around 2350 nm.

12. The system of claim 1, wherein the first wavelength band has a bandwidth less than or equal to 200 nm full width at half maximum.

13. The system of claim 1, wherein each of the plurality of emitters comprises at least one of a light emitting diode (LED) and a laser diode.

14. The system of claim 1, wherein at least one of the plurality of detectors comprises an InGaAs photodetector.

15. A system for blow-molding containers, the system comprising:

an oven for heating blow-molded container performs;

a blow molder for molding the heated performs into blow-molded containers; and

an inspection system for measuring a property of the blow-molded containers as the blow-molded containers pass through an inspection area after molding by the blow molder, the inspection system comprising;

a plurality of emitters, wherein at least a first portion of the plurality of emitters is configured to emit light energy at a first wavelength band and at least a second portion of the plurality of emitters is configured to emit light energy at a second wavelength band, wherein the plurality of emitters are configured such that emissions in the same wavelength band from spatially adjacent emitters are offset in time;

a plurality of detectors, wherein each of the plurality of detectors is aligned to receive light energy emitted by at least one of the plurality of emitters and is sensitive to light energy in the first wavelength band and in the second wavelength band; and

at least one processor in communication with the plurality of emitters and the plurality of detectors, wherein the processor is programmed to;

receive from the plurality of detectors a first signal indicating light energy in the first wavelength band received by at least one of the plurality of detectors through the blow-molded container;

receive from the plurality of detectors a second signal indicating light energy in the second wavelength band received by at least one of the plurality of detectors through the blow-molded container; and

determine a characteristic of the blow-molded container considering the first signal and the second signal.

16. The system of claim 15, wherein the at least one processor is further programmed to send a control signal to the oven to change a parameter of the oven based on the characteristic determined by the at least one processor.

17. The system of claim 15, wherein the at least one processor is further programmed to send a control signal to the blow molder to change a parameter of the blow molder based on the characteristic determined by the at least one processor.

18. A method of measuring a property of a blow-molded container, the method comprising:

emitting light energy at a first wavelength band through a blow-molded container as the blow-molded container passes through an inspection area using at least a portion of a plurality of emitters, wherein emissions at the first wavelength band from spatially adjacent emitters are offset in time;

detecting the light energy in the first wavelength band transmitted through the blow-molded container;

emitting light energy at a second wavelength band through the blow-molded container;

detecting the light energy in the second wavelength band transmitted through the blow-molded container; and

determining a characteristic of the blow-molded container considering the light energy in the first wavelength band transmitted through the blow-molded container and the light energy in the second wavelength band transmitted through the blow-molded container.

19. The method of claim 18, wherein the emitting light energy in the first wavelength band and the emitting light energy in the second wavelength band is performed by a plurality of emitters.

20. The method of claim 18, wherein the detecting the light energy in the first wavelength band and the detecting the light energy in the second wavelength band is performed by a plurality of detectors, wherein each detector of the plurality of detectors is sensitive to light energy in the first wavelength band and in the second wavelength band.

21. A method of manufacturing a blow-molded container, the method comprising:

heating a preform with a preform oven;

forming a blow-molded container from the heated preform by a blow-molder;

emitting light energy at a first wavelength band through the blow-molded container as the blow-molded container passes through an inspection area after formation of the blow-molded container by the blow-molder using at least a portion of a plurality of emitters, wherein emissions at the first wavelength band from spatially adjacent emitters are offset in time;

detecting the light energy in the first wavelength band transmitted through the blow-molded container;

emitting light energy at a second wavelength band through the blow-molded container;

detecting the light energy in the second wavelength band transmitted through the blow-molded container; and

determining a characteristic of the blow-molded container considering the light energy in the first wavelength band transmitted through the blow-molded container and the light energy in the second wavelength band transmitted through the blow-molded container.

22. The method of claim 21, wherein the emitting light energy in the first wavelength band and the emitting light energy in the second wavelength band is performed by a plurality of emitters.

23. The method of claim 21, wherein the detecting the light energy in the first wavelength band and the detecting the light energy in the second wavelength band is performed by a plurality of detectors, wherein each detector of the plurality of detectors is sensitive to light energy in the first wavelength band and in the second wavelength band.

24. The method of claim 21, further comprising changing a parameter of the oven based on the characteristic.

25. The method of claim 22, further comprising changing a parameter of the blow molder based on the characteristic.