Sony today (Wednesday) blamed a huge fall-off in revenue from its film division for being partly responsible for a 20-percent plunge in quarterly operating profit in the last yarter. Sony said its operating profit fell to $1.5 billion, down from $1.89 billion in the comparable quarter a year ago. Sony was also unable to turn out a film that was the equal of Spider-Man and Men in Black 2 at the box office. Sony also cited a slowdown in sales of its PlayStation 2 game consoles, although it reported improvement in sales of DVD recorders and flat-panel TV sets.