| 摘要 |
PURPOSE:To automatically obtain a prescribed display contrast by detecting the voltage level supplied to an LCD, (liquid crystal display element) driving circuit and selecting such LCD driving voltage in accordance with the detected level that the prescribed display contrast is obtained. CONSTITUTION:The output is a level detecting circuit 10 is fetched and is converted to a level corresponding to a prescribed display contract out of 16 stages of level (0-15). A reference value is subtracted from the converted value, and the resultant is given to flip flops F0-F3 of an LCD driving circuit 3 as a 4-bit selecting signal. Then, the LCD driving voltage given from the LCD driving circuit 4 to display memory 2 is changing to obtain the prescribed display contrast. Though the reference value is 0 normally, the reference value is in putted with the operation of operation key 6 and is written in a RAM 3 when a user requires the change of contrast.
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