| 摘要 |
PURPOSE:To check abnormalities of a beam detecting means before it happens that beams can not be detected, thereby to prevent interruption of printing by arranging to detect that the strength of said beam incident upon said beam detecting means is lowered to a predetermined value. CONSTITUTION:A laser beam B scanned by a rotary mirror 12 is detected by a beam detecting means 14 outside the recording area of a photosensitive body 13. A driving means 15 inputs a modulation signal on the basis of a beam detecting signal output from the beam detecting means 14, whereby a laser oscillator 11 is driven in accordance with the modulation signal from the driving means 15. Thus, data is recorded at a predetermined position on the photosensitive body 13. A beam strength detecting means 16 detects, on the basis of the beam detecting signal output from the beam detecting means 14, that the strength of the laser beam B incident upon a photo- receiving surface of the beam detecting means 14 is lowered to a predetermined value. In consequence, based on the output of the beam strength detecting means 16, a controlling means 17 controls an informing means 18 to inform the result of the detection by the beam strength detecting means 16 before the beam comes not to be detected due to the deterioration of the strength of the laser beam B incident upon the photo- receiving surface of the beam detecting means 14. |
