Bill Cosby To Alleged 15-Year-Old Victim You Extorted Me In Bogus Lawsuit

12/4/2014 11:51 AM PST

Bill Cosby is lashing out at the woman who claims he got her drunk and then sexually assaulted her at the Playboy Mansion in 1974 ... saying she's a liar who tried extorting him and raising the price as new women came forward.

Cosby just filed legal docs -- obtained by TMZ -- in which he says Judy Huth's lawyer approached his attorney, Marty Singer, last month and made "ominous references to criminal penalties." The docs say Huth's lawyer demanded $100K for silence, and later increased the demand to $250K as more women came forward.

In the new docs, Cosby notes the woman -- who is now 56 years old -- tried to sell the story to the tabloids around 10 years ago but no one bit. So the comedian says it's total BS that she would now say she had a repressed memory, which would allow her to file a  civil lawsuit. In other words, she'd have to file suit within 3 years of the time she remembered, but she supposedly remembered a decade ago.

The docs say her story falls apart because she claims she and Cosby played a "drinking game" 40 years ago ... yet Cosby is "a life-long non-drinker."

The docs also say Huth's lawyer was sketchy when he tried squeezing money out of Cosby, not even knowing if Huth went to a therapist.

Cosby is demanding that the lawsuit get dismissed, and he wants monetary sanctions as well.