| 摘要 |
1,089,408. Modulating light; pulse circuits. INTERNATIONAL BUSINESS MACHINES CORPORATION. Oct. 14, 1965 [Feb. 24, 1965], No. 43567/65. Headings H3P and H4F A circuit for charging and discharging a capacitive load, e.g. an electro-optic crystal 8, comprises a tank capacitor 12 connected through an inductance 10 to the unearthed crystal plate 9 so as to form an oscillating circuit. Diodes D1 and D2 which block the flow of current towards the inductance but permit current to flow in the opposite direction are connected at the ends of the inductance and are by-passed by switches S1 and S2 which are closed intermittently by pulses derived from the data pulses, as shown, so as to transfer electrostatic energy from the tank capacitor to the crystal plate and then to return electrostatic energy from the crystal plate to the tank capacitor. After each return of energy to the tank capacitor i.e. after switch S2 is opened, a voltage pulse is applied to the tank capacitor through diode D4 to compensate for any losses, e.g. resistance losses, occurring during the operation of the circuit, and at the same time to ensure that the crystal is completely discharged the voltage on conductor 14, which is connected through diode D3 to the crystal plate and is normally subjected to a voltage equal to the initial voltage to which the tank capacitor is originally charged, is reduced to zero. The voltages on conductors 14 and 16 are derived from clock pulses which arc differentiated 20, delayed 22 and applied to a monostable circuit 24. In order that a half wave voltage may exist on the crystal by the discharging of the tank capacitor it is necessary that the initial voltage be greater than the half wave voltage by an amount equal to the voltage remaining on the tank capacitor after discharging. When the half wave voltage is applied across crystal 8 the plane of polarization of the plane polarized light from source 4 is changed by 90 degrees and thus the light is deflected in birefringent element 6. |
