Image memory.

摘要

An image memory comprises a plurality of memory cell columns (40) for memorizing image data having a predetermined number of bits, common word lines (50) for connecting corresponding memory cells of these memory cell columns, scanning means (52) for sequentially designating memory cells of the memory cell columns on the basis of the scanning operation in synchronism with a clock signal, a column address counter (58) for counting the clock signal to output a column address signal, a write column selector (56) responsive to the column address signal to select a memory cell column into which image data is written, write means (56) for writing image data into the memory cell designated by the scanning means of the memory cell column selected by the write column selector, a read column selector (60) for selecting a memory cell column different from the memory cell column selected by the write column selector, and read means (60) for reading image data from the memory cells designated by the scanning means of the memory cell column selected by the read column selector. The image memory is capable of performing write and read operations at the same time. For performing a refresh operation simultaneously with read/write operation, a read/write/refresh selector may be provided instead of a read/write selector provided in the column address counter. Further, for realizing write and read operations at the same time even when a write clock signal is different from a read clock signal, the memory cell columns may be divided into a plurality of memory cell column groups e.g. odd and even memory cell groups.