| 摘要 |
PROBLEM TO BE SOLVED: To set a proper input threshold, even when the level of an input signal becomes uncertain due to factors, such as deterioration by selecting one or plural input thresholds to be selected among the prescribed number of input thresholds, based on the level of the input signal. SOLUTION: A voltage comparator 1 outputs an L/H level, whether the input signal IN of a plus input terminal becomes lower or higher than a minus input terminal VR1. An AND gate 2 outputs the logical product of the output of the voltage comparator 1 with the clock signal CLK. When a clock signal CLK is a stationary signal, the AND gate 2 is set to a signal CLK output impossible state or a possible state, by whether the output of the voltage comparator 1 is L or H. A signal VCC, that is, the H level is connected to each data input part D, and the output of the AND gate 2 is connected to each clock input part CK in a shift register 3. The proper input threshold is set by a decoder 4 and by a comparison level and input threshold selecting switches 5 and 6.
|
