A quick search of the US Patent database yielded the following patents: Pentax was awarded Patent 4097876 in 1978 for what looks like the LX system. The application was filed in 1976 and refers to the following earlier patents: 3994001, filed by Olympus in 1974, has drawings that look similar to the Pentax patent; patents 3730063 and 3791276, filed by Minolta in 1971, both describe Off The Film or Off the Shutter metering, but the drawing configurations are a little different from the Pentax and Olympus patents.
If you'd like to take a look at these cool historical documents yourself, you can find them at the US Patent and Trademark Office website: http://164.195.100.11/netahtml/search-adv.htm --Mark - This message is from the Pentax-Discuss Mail List. To unsubscribe, go to http://www.pdml.net and follow the directions. Don't forget to visit the Pentax Users' Gallery at http://pug.komkon.org .
