公开(公告)号：JP2000032763A

公开(公告)日：2000-01-28

申请号：JP12206199

申请日：1999-04-28

Applicant: ST MICROELECTRONICS INC

Inventor： MIHARA MASAAKI

IPC: G05F1/10 ,  H02M7/48 ,  H02M7/538 ,  H02M7/5381 ,  H05B33/08 ,  H05B37/02

Abstract: PROBLEM TO BE SOLVED: To provide a light and inexpensive power circuit driving the capacitive load of an electroluminescent panel and the like. SOLUTION: A phase inverter 12 has an input terminal connected to the output terminal of a differential amplifier 11 and outputs two output signals whose phases are opposite. A push pull driving circuit 13 has primary and secondary input terminals connected to the phase inverter, and has primary/ secondary output terminals connected to a switching element that is mutually turned on/off by driving it by the two output signals which are supplied from the output terminal of the phase inverter and whose phases are opposite. A single turn transformer 14 has taps 14a and 14b connected to a power terminal and a tap 14c connected to primary/secondary output terminals in the push pull driving circuit. Thus, the capacitive load of the electroluminescent panel 16 and the like can be connected to both sides of the single turn transformer.

公开(公告)号：JPH11346481A

公开(公告)日：1999-12-14

申请号：JP7813799

申请日：1999-03-23

Applicant: ST MICROELECTRONICS INC

Inventor： MIHARA MASAAKI ,  CASSIS MARCO

IPC: G09G3/30 ,  H02M7/5387 ,  H05B33/08

Abstract: PROBLEM TO BE SOLVED: To drastically reduce the loss of energy by a method, wherein a Zener diode is connected in series with switching circuits connected to both sides of a capacitive load. SOLUTION: A connection point C of the cathode of a first diode 18 to an electroluminescent(EL) panel 19 is grounded via a first Zener diode 21 and a third switching transistor 22 as constant-voltage elements, which are connected in series. In addition, a connection point D of the cathode of a second diode 20 to the EL panel 19 is grounded, via a second Zener diode 23 and a fourth switching transistor 24. The cathode of the first Zener diode 21 and the cathode of the second Zener diode 23 are connected in the direction of the EL panel 19, and their threshold voltages are made higher than the supply voltage of a DC power supply. As a result, the loss of energy can be reduced, and the EL panel 19 can generate bright light over a long period.