Abstract: A cooling liquid 28 with a boiling temperature lower than the maximum allowed temperature for the operating atmosphere of switching elements 42 and which is highly insulative is used to liquid seal the switching elements 42. This cooling liquid 28 is cooled by a liquid cooler 50. The cooling liquid 28 vaporizes and removes the heat generated by the switching elements 42 to cool the switching elements 42. Vaporized cooling liquid 28 is cooled by the liquid cooler 50 and is liquefied. The switching elements 42 can be efficiently cooled and the size of the apparatus can be reduced.

Abstract: A MOS transistor (Q.sub.M) detects an increase of the collector current (I.sub.C) of an IGBT device (Q.sub.O). When an excess current passes, the transistor (Q.sub.M) turns on, which restricts the gate voltage (V.sub.G) of the IGBT device (Q.sub.O) to decrease the collector current (I.sub.C). This protects the IGBT device (Q.sub.O) from the excess current. A Zener diode (D.sub.Z) placed on a path which is for detecting the excess current of the IGBT device (Q.sub.O) restricts the current passing through the path. This decreases reactive power which is consumed in protecting the device (Q.sub.O) from the excess current while protecting a drive circuit from an erroneous operation.

Abstract: The present invention relates to an improvement in an electrode structure of a semiconductor device having a MOSFET chip, wherein a source terminal is directly connected to a source electrode of the semiconductor device so that the source terminal overlaps with the source electrode. By employing the electrode structure, a semiconductor device having a high switching speed, low power loss and high mass productivity is obtained.

Abstract: One surface of a cathode sliding compensator is finished as an irregular surface while another surface thereof is finished as a sliding surface. The irregular surface is arranged to contact with a cathode electrode layer of a semiconductor element while the sliding surface is arranged to contact with a cathode conductor, and junction surfaces therebetween are electrically and mechanically connected by pressurization. Thus, the irregular surface bites into the cathode electrode layer to attain excellent electrical and mechanical connection between the cathode electrode layer and the cathode sliding compensator, while slidingness can be effectively retained between the cathode conductor and the cathode sliding compensator by the function of the sliding surface.

Abstract: An automatic exposure adjusting device for use in a variable copying magnification type copying apparatus, which controls quantity of light of a light source by detecting photographic density of an original document by the use of a photo detector and includes a shielding plate formed with a slit aligned with an optical path for subjecting a photosensitive member to exposure. The photo detector is provided below and adjacent to the light source, while the shielding plate is provided below and adjacent to a copy face of the original document.