| 摘要 |
<p>PURPOSE: To protect an element from damage due to a parasitic high electric field induced in a circuit when control voltage for a liquid crystal display screen is switched by preparing a protection circuit provided with three specific transistors(TRs). CONSTITUTION: In the case of controlling the columns of the liquid crystal display screen, a means 10 receives video voltage V and samples the voltage V by a sampling pulse ECH, so that voltage to be transferred to an output plot S so as to be impressed to the columns C of the screen appears on the output (s) of the means 10. The control circuit CCC is provided with the protection circuit CP, TRs T1, T2 are connected in series between the output (s) and a plot S, a TR T3 is connected between the intermediate point (m) of the TRs T, T2 and a point M led to an earth, and these TRs are controlled by signals S1 to S3 generated from a circuit 20. The signal S1 closes the TRs T1, T2 and opens the TR T3. The signal S2 opens the TRs T1, T2 and closes the TR T3. The signal S3 closes the TRs T2, T3 while opening the TR T1.</p> |
