ARTICLE INSPECTION BY SUCCESSIVELY TELEVISED IMAGES

• US 3,598,907 A
• Filed: 05/20/1968
• Issued: 08/10/1971
• Est. Priority Date: 05/20/1968
• Status: Expired due to Term

• Current Assignee: Edward J. Stephens, William H. Drinkuth
• Original Assignee: Edward J. Stephens, William H. Drinkuth
• Inventors: Drinkuth, William H., Stephens, Edward J.
• Application Number:
  US04/730,377
• Time in Patent Office: 1,177 Days
• US Class Current: 348/127
• CPC Class Codes: G01B 11/022 by means of tv-camera scanning
• CPC Class Codes: G01N 2033/0081 containers; packages; bottles
• CPC Class Codes: G01N 21/9027 in containers after filling
• CPC Class Codes: H04N 7/18 Closed-circuit television [CCTV] systems, i.e. systems in which the video signal is not broadcast

Abstract

A liquid-filled transparent container is spun momentarily to cause the liquid therein to swirl, and successive video frames provide voltage analogs through a television camera. A memory device is synchronized with the camera and stores at least one of the voltage analogs so that a comparator can subtract one successive analog signal from another to generate an error signal if foreign particles are present in the swirling liquid.

Claims

1. A method for inspecting articles wherein each of said articles comprise a transparent container containing a quantity of liquid, 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, b. scanning the article with a television camera to produce a voltage signal indicative of the image seen by said camera, c. storing said voltage signal in a memory device for subsequent use, d. moving the container so that the orientation of the liquid to be inspected is altered, e. scanning the article a second time with said television camera to produce a second voltage signal representing the second image seen by said camera, f. comparing said voltage signals to provide an error signal whenever said second voltage signal does not bear a predetermined relationship to said first voltage signal, and g. synchronizing said voltage signals with respect to one another, said step of comparing said synchronized voltage signals comprising a process of subtracting said first and second voltage signals from one another to produce said error signal when the difference exceeds a threshold value.

2. A system for inspecting a liquid filled transparent container which is to be inspected for the presence of foreign particles in the liquid, and comprising means for rotating the article momentarily so that the liquid is allowed to swirl while the article is held at an inspection station, a television camera for viewing said article, means for causing said camera to generate successive voltage signals indicative of said article images, a memory device for storing at least one such voltage signal, switching means causing said stored voltage signal to be recalled in timed relationship with a succeeding voltage signal, a comparator for combining said recalled voltage with said succeeding voltage and for generating an error signal whenever said signals do not bear a predetermined relationship to one another and, means for synchronizing said camera with said memory device so that said voltage signals are fed to said comparator in accurately indexed relationship to one another.

3. The system according to claim 2 and further including a light source so arranged adjacent one end of the container as to illuminate the particles.

4. The system according to claim 3 wherein said comparator subtracts said voltage signals from one another to provide said error signal, and a reject device operable in response to said error signal to separate a container with foreign particles from these containers without foreign particles.

5. A method for inspecting transparent containers for the presence of foreign particles in a liquid contained therein, said method comprising the steps of a. spinning the container so that the liquid contents are swirled therein, b. scanning the coNtainer and its contents with a television camera to produce a voltage signal indicative of the image seen by said camera, c. storing said voltage signal in a memory device, d. scanning the container and its contents a second time to produce a second voltage signal representing the second image seen by said camera, and e. recalling the stored voltage signal to compare it with said second voltage signal.

6. The method according to claim 5 and further characterized by the steps of a. synchronizing said voltage signals with respect to one another, b. comparing said voltage signals to provide an error signal whenever said second voltage signal does not bear a predetermined relationship to said first voltage signal.

7. The method according to claim 6 and further characterized by the additional step of stopping the rotation of said spinning container prior to the scanning steps so that only the liquid contained therein continues to move between said scanning steps, said step of comparing said synchronized voltage signals comprising a process of subtracting said first and second voltage signals from one another to produce an error signal which is not effected by stationary particles on the container and not effected by defects in said transparent containers.

8. The method according to claim 6 and further characterized by rejecting said container when the amplitude of said error signal exceeds a threshold value.

9. The method according to claim 6 and further characterized by rejecting said container when the time base width of said error signal exceeds a length corresponding to a predetermined particle size.

10. A method for inspecting articles comprising the steps of a. placing the article at an inspection station, b. scanning the article with a television camera to produce an electric signal which varies in accordance with the image seen by said camera, c. storing said signal in a memory device for subsequent use, d. rotating the article so that the orientation of the inspection portion with respect to the camera is altered, e. stopping rotation of the article to cause swirling of the liquid, f. scanning the article a second time with said camera to produce a second electric signal, g. synchronizing said signals with respect to one another, and h. comparing said signals to provide an error signal whenever said first and second signals do not bear a predetermined relationship to one another.

11. The method according to claim 10 wherein said step of comparing said first and second signals comprises a process of subtracting one from the other to produce said error signal in response to moving particles in the swirling liquid, said error signal being uneffected by stationary particles on the container and uneffected by optical defects in the transparent container.

12. The method according to claim 10 and further characterized by the additional step of illuminating the container from a light source so that the liquid provides a relatively dark background against which the particles stand out for a better contrast in the field of view of the camera.

13. A system for inspecting liquid filled transparent containers for the presence of foreign particles in the liquid, said system comprising a. means for supporting an article at an inspection station, b. means for rotating the article on its longitudinal axis, said means for rotating the container being carried out long enough to impart a swirling motion to the liquid and to any foreign particles therein, said article being held stationary at least momentarily, c. a television camera for generating successive video frames, each of said frames includes a pattern of electrical signals which vary in accordance with the successive images seen by said camera, d. a memory device for storing at least one such pattern of electrical signals, e. synchronizing means for said stored signals, f. and a comparator for combining saiD stored signals with a current video frame to generate an error signal whenever said compared patterns of electrical signals do not bear a predetermined relationship to one another, said comparator being effective to subtract said pattern of electrical signals from one another to generate said error signal.

14. The system according to claim 13 further characterized by a reject device operable in response to said error signal to separate a container with foreign particles from those without foreign particles.

15. The system according to claim 13 further characterized by a light source adjacent one end of the container at said inspection station for illuminating the particles in the liquid filled container.