| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To solve the problem with a constant current circuit for controlling currents of a plurality of LEDs, wherein the circuit is complicated and has limitations on cost reduction because it includes, e.g., an MOSFET and an IC controlling the MOSFET. <P>SOLUTION: A plurality of p-type impurity regions are disposed with equal spacing on the surface of an n-type semiconductor layer, and a first metal layer is provided to form an ohmic contact with the p-type impurity regions on the entire surface and to form a Schottky junction with the n-type semiconductor layer. By using it so as to apply a reverse voltage to the pn junction, a constant current drive element for controlling current flowing by pinch-off current can be provided. Only by connecting the element in series on low voltage side of the LED, a current flowing through the LED by the pinch-off current can be controlled as a constant value. Thus, an inexpensive and simple LED drive circuit can be achieved as compared with a constant current circuit having a combination of an MOSFET and an IC for gate control. <P>COPYRIGHT: (C)2011,JPO&INPIT</p> |
