| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a display device of an electronic musical instrument which has excellent visibility and whose power consumption can be suppressed low. <P>SOLUTION: The input potential of a logic gate G2 instantaneously rises to H, but then gradually falls along a discharge curve based upon the time constant of a capacitor C1 and a resistance R3. When the input potential of the logic gate G2 is higher than a threshold potential, a transistor Tr1 is turned on. The cathode of an LED 1 is therefore grounded through a resistance R2. An output Q, on the other hand, is at L, so the cathode of the LED 1 is grounded through a resistance R1 and a diode D1 and then grounded by the resistances R1 and R2 in parallel, so that the LED 1 illuminates brightly (with first lightness). When the input potential of the logic gate G2 gradually falls below the threshold potential, the transistor Tr1 is turned off. The LED 1, therefore, has second lightness (second mode) darker than the first lightness (first mode). <P>COPYRIGHT: (C)2007,JPO&INPIT |
