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    • 4. 发明专利
    • ELECTROMAGNETIC ULTRASONIC WAVE MEASURING APPARATUS
    • JPS6395352A
    • 1988-04-26
    • JP24131886
    • 1986-10-13
    • HITACHI LTD
    • KADOWAKI TAKASHIITO SUSUMUOZAKA AKIRAFUJITA YASUNOBU
    • G01B17/02G01N29/04
    • PURPOSE:To enable easy and accurate inspector of a defect or the like of material, by providing a circuit to perform a subtraction of a detection signal of an ultrasonic transmitting/receiving coil and a detection signal of a compensation coil. CONSTITUTION:When excited with a DC power source 3, a DC coil 22 generates a DC magnetic flux 4. The magnetic flux 4 is composed mostly of a component 41 vertical to the surface of material 1 to be inspected below the center leg end of a core 21 while containing a parallel component 42. On the other hand, when a pulse current is applied to a transmitting coil 23 from a pulse generator 5, an eddy current 6 is generated on the surface of the material 1. A transverse ultrasonic wave is generated from the eddy current 6 and the component 41 of the magnetic flux 4 or a longitudinal ultrasonic wave is generated from the component 42. The ultrasonic waves reflected from an internal defect of the material 1 are received with a receiving coil 24, mostly as transverse ultrasonic waves and a slightly as longitudinal ultrasonic waves. On the other hand, below the center leg side of the core 21 with a compensation coil 25 set thereon, the magnetic flux 4 mostly consists of a component 43 parallel with the surface of the material 1 and mainly, a longitudinal component is received. The received waves of the coils 24 and 25 are subtracted 7 and a transverse wave component alone of the received wave of the coil 24 is displayed 8 to detect a defect.
    • 6. 发明专利
    • COOLER FOR ELECTRONIC PART
    • JPS58101447A
    • 1983-06-16
    • JP19864581
    • 1981-12-11
    • HITACHI LTD
    • YODA MIKIOSHIBATA EKIZOUOZAKA AKIRASHINOHARA YASUSHI
    • H01L23/36H05K7/20
    • PURPOSE:To effectively cool an electronic part by bonding a gel-like heat transfer medium between a heat sink plate and a printed board and forming a gap which surrounds the periphery of the specific electronic part on the board between the medium which faces the part and the plate. CONSTITUTION:Si gels (heat transfer media) 6a, 6b are formed at both sides of a printed board 1, on which electronic parts 2 are mounted, and heat sink plates 3a, 3b are clamped with screws 8. Slits 11 are formed around the electronic parts between the gel 6a which is contacted with the specific electronic part 2 and the plate 3a. The slits 11 prevent the transfer of heat from other to the parts which less heat ad are weak for the heat. Further, an escaping groove 7 at the clamping and deforming time is formed at the gel 6b bonded to the plate 3b, and a front panel 9 is coupled integrally with the board 1. The printed board unit is cooled by air with a plurality of air gaps formed in parallel. According to this structure, even if a large local heating part exists, the temperature distribution is uniformly performed, effective cooling can be performed while protecting the part which is weak for the heat.
    • 8. 发明专利
    • Short circuit protecting circuit of transistor
    • 短路电路保护电路
    • JPS57118439A
    • 1982-07-23
    • JP318781
    • 1981-01-14
    • Hitachi Ltd
    • OZAKA AKIRAICHIISHI TSUNEOYODA MIKIOSHINOHARA YASUSHIISHIYAMA FUMIO
    • H03K17/08H03K17/082H03K17/64
    • H03K17/0826
    • PURPOSE:To realize a short circuit preventing circuit of a transistor which prevent the transistor from the breakdown due to a short circuit, by connecting a resistor for detection of current in series to a load and turning on a protecting transistor with the voltage at the both ends of the resistor. CONSTITUTION:When a short circuit occures across a load 1, the current flowing through a resistance 14 increases. When this current exceeds the Zener voltage of a Zener diode 17, the base current flows to a transistor (TR)15. As a result, a large current is poured to the base of a TR5 through a resistance 18. This increases the collector current of a TR4. At the same time, the base current increases more than the short circuit current. As a result, the TR4 keeps the saturated state even after the occurrence of a short circuit to reduce the loss caused within the TR4. Meanswhile a fuse 13 is fused to prevent the breakdown of the TR4.
    • 目的:为了实现防止晶体管由于短路导致的击穿的晶体管的短路防止电路,通过将用于电流检测的电阻器连接到负载并以两端的电压来接通保护晶体管, 电阻端。 构成:当穿过负载1发生短路时,流过电阻14的电流增加。 当该电流超过齐纳二极管17的齐纳电压时,基极电流流向晶体管(TR)15。 结果,通过电阻18将大电流注入TR5的基极。这增加了TR4的集电极电流。 同时,基极电流大于短路电流。 结果,即使发生短路,TR4也保持饱和状态,以减少在TR4内引起的损耗。 同时,熔断器13被熔断以防止TR4的击穿。