| 摘要 |
<p>An inexpensive A-D converter circuit comprising a signal conversion circuit for converting an analog signal into a digital signal based on a reference voltage, in which the whole reference voltage is varied periodically, the output signal just ahead of the signal conversion circuit is held by an output buffer, and the output signal of the signal conversion circuit and the signal just ahead are added. Also, in the A-D converter circuit, after the above addition, a difference between two consecutive pieces of data of the output data of the signal conversion circuit is detected. When the data difference is within a given range, then the output of the above addition is selected, while for the data difference exceeding the given range double the above output is selected. Further, to be able to increase the number of gradations without expanding the capacity of a display memory, parallel data stored in the display memory for image display purposes are respectively received and held by a latch whenever they are output from the display memory, and the next data output from the display memory and the data output from the latch are added.</p> |
