| 摘要 |
In a horizontal AFC circuit, a window output is produced from a window generating circuit 4 in response to an AFC output having a relatively long time constant, derived from a first AFC circuit 2. The window output is synchronously differentiated by an edge detecting circuit 5. Another AFC output having a relatively short time constant, derived from a second AFC circuit 3, is present within a window range under the normal condition. A horizontal oscillation output derived from an OR circuit 10 into which outputs from a DFF 8 and an AND circuit 7 are inputted, corresponds to the AFC output from the second AFC circuit 3. Also, when the AFC output of the second AFC circuit 3 is not present within the window range, the output from the OR circuit 10 corresponds to the edge outputs from the edge detecting circuit 5.
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