CROSS-TRACK DISTRIBUTOR FOR VIDEO SIGNALS

摘要

1,216,957. Transistor gating circuits. FERNSEH G.m.b.H. 8 Aug., 1969 [9 Aug., 1968], No. 39817/69. Heading H3T. Colour television signals are switched over a matrix the cross-points of which are produced as integrated circuits on small plates of semiconductor material. A cross-point circuit is shown in Fig. 2 where the input 21 is connected to an output 23 when a switching signal is applied to terminal 25 to thereby switch off normally conducting transistor 109 to raise the potential at point 110 causing diodes 103, 107 to conduct and diode 104 to be cut off. A fixed voltage on terminal 26 is such that, with the cross-point switched off, diode 104 conducts and shunts any residual signal on the input that finds its way over transistor 101 and diode 103. Amplifiers are used in the input and output circuits of the matrix, the input circuit amplifiers having a low output impedance so that a single input may be connected to a number of outlets without affecting the input.