GB344315A - Improvements in and relating to cathode beam oscillographs - Google Patents

Abstract

344,315. Oscillographs. ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Bush House, Aldwych, London.-(Assignees of Ackerman, O.; 470, Ella Street, Wilkinsburg, Pennsylvania, U.S.A.) June 23, 1930, No. 19058. Convention date, June 22, 1929. [Class 37.] In order to excite the timing plates of a cathode beam oscillograph, a condenser is normally maintained charged by a stream of electrons impinging on a target, and is allowed to discharge through a resistance when the electron stream is deflected away from the target. As shown in Fig. 1, an evacuated glass vessel 1 contains a heated cathode 2, an anode 4, deflecting plates 10, a metal screen 8, and a target 7, the anode 4 and screen 8 having central holes in alignment with the cathode and target. The anode 4, screen 8, and one of the plates 10 are connected to earth, the other plate 10 being connected to a point on a series of condensers 13 connected between a hightension line 14 and earth, and forming a potential divider. The target 7 is connected to earth through a resistance 15 across which are connected the electro-static timing plates 16 of the oscillograph. If the capacity of these plates is insufficient, a condenser 17 is connected in parallel therewith. When there is only a normal voltage on the line 14, the beam of electrons is directed on to the target 7, causing a current through the resistance 15 the potential across which maintains the plates 16 and condenser 17 charged. On the occurrence of a surge or unusually high voltage on the line 14, the electron beam is deflected off the target 7 and against the screen 8, thereby interrupting the current through the resistance 15 and allowing the plates 16 and condenser 17 to discharge through the resistance 15 at a known rate, thereby imparting a known timing movement to the electron beam of the cathode ray oscillograph. In a modification the apparatus is combined with a cathode ray oscillograph of the kind described in Specification 295,321, [Class 37, Electricity, Measuring &c.], so that a single cathode beam serves as the oscillograph beam and for initiating the timing movement.