HUBERTUS SCHRADE PATENT ? penblade release patent nfo wanted

[BACKSPRINGER]

I've searched hundreds of patents , has anyone ever viewed the patent for the pen blade release switchblade knife produced by Hubertus ? I wonder was it patented ? When ? Was it produced by anyone else before Hubertus ? Could this be the patent sold by Schrade before he left Germany ? Some literature suggests he did , however it is my understanding that he was in Germany sometime before 1916 and Kuno Ritter didn't set up shop until 1932 .Does anybody know for sure what German company bought it ? If Schrade did sell a patent would'nt it have remained in his name ? It seems that only the assignee would change . Anyone knowlegable about patent searching out there ? can anyone give me the patent information , drawings of this knife ?

[knife7knut]

I realize this is an old post but as I recall pen blade release mechanisms were prevalent on large folding knives in the mid 19th century.You would probably have to research English and/or German patent archives.