| 摘要 |
PURPOSE:To enable an abnormal rotation of a type wheel to be securely detected, by a system wherein during the time when a plurality of type wheels are rotated a predetermined angle from an initial position, it is detected by a photosensor whether two through-holes provided in each of the type wheels are communicated with each other. CONSTITUTION:When each of the type wheels 1-1-1-n is located at the initial position, the through-holes 21, 22 provided in each of the type wheels are communicated with each other in line, so that light from a light emitter 11a of a transmission type photosensor 11 passes through the through-holes 21 to be received by a light receiver 11b, an initial position return discriminating circuit 13 discriminates the returning to the initial position of each of the type wheels on the basis of a signal S2 from a detecting circuit 12, and an abnormality discrimination signal S8 is not outputted from a rotation abnormality discriminating circuit 17. After a printing operation is started, the through-holes 21, 22 are moved in the mutually communicated condition until the rotation of the type wheels is stopped by the first type- selecting piece, and when the type wheels are rotated by a predetermined angle, the through- holes 22 come to a position in registration with the photosensor 11. At this moment, when abnormal rotation is present in one of the type wheels, the light receiver 11b does not receive light, and the circuit 17 outputs the signal S8. Accordingly, misprinting can be prevented from occurring.
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