Product segment and geographic information (Details) (USD $)	3 Months Ended		6 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 31, 2013	Mar. 31, 2012
Total sales	$ 10,435,935	$ 11,320,988	$ 22,366,313	$ 26,748,215
Video Recorder Products [Member]
Total sales	5,617,210	6,337,583	12,177,361	14,663,921
Tv Receiver Products [Member]
Total sales	3,922,930	4,036,006	8,272,616	10,174,117
Non Tv Receiver Products [Member]
Total sales	$ 895,795	$ 947,399	$ 1,916,336	$ 1,910,177