| 摘要 |
PURPOSE:To prevent a malfunction in synchronization change by providing a means which detects whether an outside video signal is inputted or not, a means which detects the state of a synchronization change switch and a means which detects the state of a mode change switch. CONSTITUTION:A signal PIN which represents the presence/absence of the input of the outside video signal is detected by a PIN input detection circuit 9 and a signal INT which represents the changing state of a synchronization change switch 3 is detected by a change logical operation circuit 8. Also, a signal CPU which represents the state of the mode change switch is detected by a mode change signal detection circuit 10. In other words, it is an internal synchronization when it is detected that the outside video signal is not inputted by the circuit 8 and when the inputting of the signal is recognized, it is an external synchronization with the recognition of the selection of the external synchronization at the circuit 9. Also, when a mode except an RGB signal output mode is selected by the circuit 10, it is the external synchronization. Thus, by an automatic synchronization change, the malfunction in the synchronization change can be prevented. |
