| 摘要 |
PURPOSE:To prevent the occurrence of partial deterioration of fluorescent surface by always evenly radiating the entire section of the scanning area of an image- exposing cathode ray tube irrespective of sizes of recording media. CONSTITUTION:The output of a paper size selecting circuit 3 having been selected to the assigned size and a start-timing generating circuit 4 control the opening and closing of AND gates 6, 16 through a gate circuit 5. This results in the connection of the switch S of the selecting circuit 12 to its contact H, the application of the specified voltage from a control power source 13 to a luminance modulating driver 11 and the change in the luminance at the scanning of the fluorescent surface of a cathode ray tube 1 according to the recording video signal of a video signal generating circuit 2. When scanning of the fluorscent surface corresponding to the paper size ends, the output of the circuit 3 inverts and the switch S of the circuit 12 is changed over by way of an inverter 10, by which the specified voltage for low luminance of a power source 14 is applied to the driver 11 and the remaining region of the fluorescent surface is scanned. Hence, the occurrence of the variation in characteristics owing to the partial deterioration of the fluorescent surface through the partial scanning along of the cathode ray tube is prevented and even recording is accomplished. |
