Pogo Ball was invented by Raphael J. Van Der Cleyen and Wilfried F. Ribbens with a Bengium patent granted in May, 1969.  They entered a licensing agreement with Les Usines Fabelty, S.A. to exploit the patent on October 27, 1969.  On February 21, 1970, it was amended to sell outright to Fabelty ownership of all patents.  March of 1970, Fabelty applied for a US patent.

Fabelty became insolvent on November 30, 1972 without ever producing the product in the US, but the patent was issued on Feb 13, 1973.

Fabelty was liquidated in 1977 under Belgium law, however there was no referencing of the US patent.  

Fast forward a little bit, 1985, after all European patents expired, the toy (Lolobal) became quite popular in Europe.

Hasbro wanted to jump on the bandwagon as quickly as possible, and it sought patent right starting May of 1986.  Hasbro started marketing the toy in November of 1986 to target Christmas with the familiar name “POGO BAL” (no, one l is not a typo).  And it became quite popular the next couple of years.