| 摘要 |
1,162,745. Typewriters etc.; selective printing. INTERNATIONAL BUSINESS MACHINES CORP. 9 May, 1967 [3 June, 1966], No. 21388/67. Heading B6F. [Also in Division H3] A thyristor circuit (see Division H3) is used to operate a print hammer winding 2. When thyristor 1 is fired to operate the hammer, a commutating capacitor 7 switches off a thyristor 4 and through a diode 12 rapidly charges a capacitor 13 with its upper plate negative. The commutating capacitor rapidly charges through a transistor 5 which is now conducting and capacitor 13 begins to charge in a positive direction through resistor 14. This continues until the capacitor voltage fires thyristor 4 and so through the action of the commutating capacitor switches off 1 and de-energizes the print hammer. If the timing components 10-14 are omitted the circuit is bi-stable. |
