| 摘要 |
PURPOSE: A laser beam printer is provided to enhance a printing quality of an image through a modulation of laser beam. CONSTITUTION: An RIP(22) receives document information including text information and image information, and outputs 1-bit bitmap information corresponded to the text information and multi-bit bitmap information corresponded to the image information in accordance with a scanning order, and outputs position information indicating a position of multi-bitmap information on a document. A 1-bit page/band buffer(24) stores 1-bit bitmap information outputted from the RIP(22). A multi-bit page/band buffer(28) stores multi-bit bitmap information outputted from the RIP(22). A position information memory(30) stores position information outputted from the RIP(22). A PVC(26) outputs the first modulation signal corresponded to the 1-bit bitmap information stored in the 1-bit page/band buffer(24) or the multi-bit bitmap information stored in the multi-bit page/band buffer(28) in accordance with a scanning order and the position information stored in the position information memory(30). In addition, the PVC(26) outputs a selection signal for separating a section outputting the 1-bit bitmap information and a section outputting the multi-bit bitmap information during the scanning period. A pulse width modulator(32) outputs the second modulation signal modulated in pulse width for modulating a size of a laser beam based on a size of the multi-bit bitmap information outputted from the PVC(26). A selector(34) selectively outputs the first modulation signal outputted from the PVC(26) or the second modulation signal outputted from the pulse width modulator(32) to a laser diode in accordance with the selection signal.
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