1. Field of the Invention
The invention, in general, relates to devices for counting containers, such as glass bottles, and more particularly, a counter that provides an accurate count of containers even when containers dither on their conveyor.
2. Description of the Prior Art
Accurate, non-contact counting of containers is essential in many industrial applications. For example, in the glass container industry production analyzing systems require accurate infeed and outfeed container counts to generate precise reports of container losses on various inspection and container handling devices along the production line. Dither has always presented a difficult problem for such counters. Dither occurs when the flow of containers is impeded and the conveyor continues to run. There are a myriad of reasons for this condition to take place: inspection equipment jams, flow control devices, conveyor jams, etc. Another common occurrence of container dither is caused by inspection and container handling devices that incorporate infeed screws. As the infeed screw rotates to feed containers into the equipment, pulsations are introduced back into the containers upstream of the device. Up to now, all counting systems, including those based on sonic, through beam, diffuse reflection, triple beam and retroreflective sensors have produced multiple "counts" for a single container when the container dithers on the sensing edge of the container counting device. In the prior art, a technique called blanking has been used to attempt to solve this problem. In this technique, the counter is blanked for a predetermined short time period after each count. However, systems that incorporate blanking do not work well, as they are sensitive to the normal line speed variation which occurs continuously in bottle handling systems. Thus it would be highly desirable to provide a container counter that does not produce multiple counts when containers dither.