| 摘要 |
PURPOSE:To prevent the duty ratio of a recording head drive from exceeding the maximum rating of a recording head and thereby to protect the recording head effectively from the runaway of a microprocessor or the like by neglecting a recording request signal during a prescribed period depending on a recording head drive time. CONSTITUTION:When recording data of 64 rasters or above corresponding to the number of recording elements are received from a host system 2 through an interface circuit 4, they are stored in VRAM 5. Next, with a carriage started to move in the horizontal direction, the recording data stored in the VRAM 5 are transferred to a shift register 9a of a recording head 9 by using a recording data transfer circuit 7. Subsequently, a drive time t1 is set in a heat time register 13 and the recording head 9 is driven to conduct recording. On the occasion, a recording request signal HREQ is neglected for a period about 20 times as long as a recording head drive time by a protection circuit. Accordingly, the duty ratio of a drive does not exceed 1/20 even in the case when a microprocessor runs away, and thus the breakdown of the recording head 9 is prevented effectively. |
