| 摘要 |
PURPOSE:To secure maximum resolution and the linearity of a full scale by comparing plural periodic pattern signals which are different in period from and equal in amplitude to an input image signal with the image signal and imposing pulse width modulation, and selecting one of pulse-width modulated image signals. CONSTITUTION:Pattern signal generation parts 101, 102, and 103 generate periodic pattern signals which have an amplitude nearly equal to the maximum amplitude of a multilevel image signal 100 and differ in period. Comparators 105 and 106 compare the image signal 100 with each periodic pattern signal and outputs a pulse-width modulated image signal of each period. A selector 107 selects one of pulse-width modulated image signal. Individual periodic pattern signals 101a, 102a, and 103a are all nearly equal in amplitude to the input multilevel image signal 100, so the maximum resolution and linearity of the full scale of all of pulse-width modulated image signals 104a, 105a, and 106a outputted by the comparators are secured. Further, if the selector 107 makes a selection according to the image tone of the multilevel image signal 100, a pulse-width modulated image signal 109 of high quality is obtained.
|
