| 摘要 |
PURPOSE:To improve the gradation with simple constitution by applying pulse width correction in response to a density level of a picture signal subject to pulse width modulation. CONSTITUTION:A picture signal 12 subject to pulse width modulation is inputted to delay lines 1-8, the signal is subject to delay of a time Td every time the signal passes through one line, a counter 9 counts a picture clock having a frequency 8 times in response to the pulse width of the picture signal 12, the signal is modulated into a 3-bit code and outputs QA-QC are ORed with the picture signal 12, inputted respectively to select inputs A-C of a selector 10 and any of data inputs D0-D7 is selected. An output Q of a flip-flop 11 is set by a leading edge of a signal outputted from the delay line 5 and reset by the leading edge with an OR signal between the output of the selector 10 and the picture signal 12. Thus, the pulse width is corrected in response to the density level of the picture signal to improve the gradation. |
