Abstract: Owing to the property of bidirectional conduction under the saturation mode, synchronous rectifiers in conventional power converters usually suffer from a reverse current under light loads or a shoot-through current under heavy loads. The reverse current may degrade the converter efficiency and the shoot-through current may damage synchronous rectifiers. The present invention discloses a unidirectional metal oxide semiconductor field effect transistor (UMOS), which comprises a metal oxide semiconductor field effect transistor (MOS), a current detection circuit and a fast turn-off circuit. The current detection circuit detects the direction of the current flowing through the MOS. When a forward current is detected, the fast turn-off circuit is disabled and the channel of the MOS can be formed. When a reverse current is detected, the fast turn-off circuit is enabled and the channel of the MOS cannot be formed.

Abstract: The present invention discloses a bridgeless active power factor corrector with a logic control comprising a high frequency switch controller, a boost inductor, an output filtering capacitor, two boost transistor modules, two boost diodes, two AC input voltage polarity detectors, and two low frequency switch drivers. With a coupling signal, the two AC input voltage polarity detectors respectively control the two low frequency switch drivers in conjunction with the high frequency switch controller to drive the two boost transistor modules with a logic control so that the inductor current releasing electric energy from the boost inductor can flow through the channels of the two boost transistor modules to effectively reduce the body diode conduction loss.

Abstract: Conventional diode rectifiers usually suffer from a higher conduction loss. The present invention discloses a gate-controlled rectifier, which comprises a line voltage polarity detection circuit, a constant voltage source, a driving circuit and a gate-controlled transistor. The line voltage polarity detection circuit detects the polarity of the line voltage and controls the driving circuit to turn on or turn off the gate-controlled transistor. The gate-controlled transistor may be a Metal Oxide Semiconductor Field Effect Transistor (MOSFET) with a gate, a source and a drain or an Insulated Gate Bipolar Transistor (IGBT) with a gate, an emitter and a collector. The constant voltage source is provided or induced by external circuits and referred to the source of the MOSFET or the emitter of the IGBT. Thanks to a lower conduction loss, this gate-controlled rectifier can be applied to rectification circuits to increase the rectification efficiency.

Abstract: The present invention relates to a forward converter with self-driven synchronous rectifiers, which utilizes a secondary driving winding and a secondary driving circuit to drive the synchronous rectifiers in the secondary power loop. The secondary driving circuit, which is composed of a level shifter and a signal distributor, can shift the voltage waveform across the secondary driving winding by a predetermined level and distribute proper driving signals to the synchronous rectifiers to reduce the rectifier conduction loss. Specially, the channel of the freewheeling synchronous rectifier still can be turned on during the dead interval to further reduce the body diode conduction loss.

Abstract: The present invention discloses a forward converter with secondary side post-regulation and zero voltage switching, where the primary side power loop may adopt a single or a dual transistor structure, driven by a primary side driving circuit with a constant duty ratio so that the voltage waveform across the secondary side power winding has a constant pulse width; the secondary side power loop uses a controllable switch, a magnetic amplifier (MA) or an N channel metal oxide semiconductor field transistor (NMOS), to blank the leading edge of the voltage waveform across the secondary side power winding, regulate the output voltage, and achieve zero voltage switching of primary side switch transistors.

Abstract: The present invention discloses a half-bridge LLC resonant converter with self-driven synchronous rectifiers, which utilizes a primary IC controller and a gate driver to drive the secondary synchronous rectifiers. In correspondence with the gate drive output voltages of the primary IC controller to the primary switch transistors, the gate driver for the secondary synchronous rectifiers comprises a differential transformer if the primary IC controller outputs two ground-referenced gate drive voltages, which cannot directly drive the primary switch transistors but can be imposed on the differential transformer; or comprises a DC shifter, a DC restorer and a differential transformer if the primary IC controller outputs two gate-source voltages, which can directly drive the primary switch transistors but cannot be imposed on the differential transformer. The drive voltages of the primary switch transistors are unipolar; however the drive voltage of the secondary synchronous rectifiers can be bipolar or unipolar.

Abstract: The detent means for a heat sink has on each of the two ends of a pressing member a fixing engaging member and a movable engaging member, the movable engaging member is provided thereon with a foldable member. Wherein the pressing member is provided on the heat sink, the fixing engaging member extending downwards to engage protrusions on a side of a fixing seat of a microprocessor, the movable engaging member can be lowered to engage with protrusions on an opposite side of the fixing seat of the microprocessor, and the movable engaging member can be raised to a predetermined level under the action of the foldable member to thereby exert a force on the pressing member, thus the heat sink and the microprocessor at the center of the fixing seat can be press connected with each other.

Abstract: A heat sink is provided. The heat sink comprises a hollow chassis having a contact face at a bottom portion thereof for attaching to an electronic component and a heat dissipating face at a top portion thereof. A plurality of circularly arranged fins extend from an inner sidewall of the hollow chassis towards a center of the hollow chassis so that gaps between the fins gradually decrease from the inner sidewall of said hollow chassis towards the center of said hollow chassis. At least a heat pipe is positioned between the contact face and the heat dissipating face. At least a fan is positioned at a side of the hollow chassis for generating air to increase an amount of air blowing through wider gaps between said fins to increase the speed of heat dissipation.

Abstract: The detent means for a heat sink has on each of the two ends of a pressing member a fixing engaging member and a movable engaging member, the movable engaging member is provided thereon with a foldable member. Wherein the pressing member is provided on the heat sink, the fixing engaging member extending downwards to engage protrusions on a side of a fixing seat of a microprocessor, the movable engaging member can be lowered to engage with protrusions on an opposite side of the fixing seat of the microprocessor, and the movable engaging member can be raised to a predetermined level under the action of the foldable member to thereby exert a force on the pressing member, thus the heat sink and the microprocessor at the center of the fixing seat can be press connected with each other.

Abstract: A heat sink is provided. The heat sink comprises a hollow chassis having a contact face at a bottom portion thereof for attaching to an electronic component and a heat dissipating face at a top portion thereof. A plurality of circularly arranged fins extend from an inner sidewall of the hollow chassis towards a center of the hollow chassis so that gaps between the fins gradually decrease from the inner sidewall of said hollow chassis towards the center of said hollow chassis. At least a heat pipe is positioned between the contact face and the heat dissipating face. At least a fan is positioned at a side of the hollow chassis for generating air to increase an amount of air blowing through wider gaps between said fins to increase the speed of heat dissipation.

Abstract: The heat-pipe type heat sink structure of the present invention comprises a heat conducting part stackable on an article to be heat sunk and multiple heat-sinking fins on the heat conducting part; wherein the heat conducting part has a through hole, two plug holes of larger diameters are provided on the two ends of the through hole, plugs coated with tin grease layers seal the plug holes by tight fitting and pressing. Then the heat sink is delivered through a hot air furnace; the tin grease layers are cooled again after being melted to complete the heat-pipe type heat sink structure.

Abstract: The conductive seat has parallelly arranged strip members in a bottom area of its base sealed therein with liquid, a plurality of flow channels are formed from and on the bottom of the strip members and are mutually spaced; a return area is formed between the top ends of the strip members and the lid; when the bottom of the base contacts with a heat-generating source, the liquid sealed in the base and absorbing the latent heat from the heat-generating source becomes a vapor flow flowing toward the return area to repeatedly circulate and transmit the heat, thereby the heat is rapidly and uniformly transmitted to the heat sink to further increase the effect of heat sinking.

Abstract: A computer heat sink, it especially suits heat sinking of various chip sets or processors which may generate high temperature during running, and has the effect of better efficiency of heat sinking and inexpensiveness of production.

Abstract: The detent means for a heat sink is provided thereon with an elastic member in connecting with two side clamp holders, the elastic member is bent to render the bending area to be the force bearing point which is communicating in force with the two side clamp holders, the thickness of a lateral arm between the bending area and one of the two side clamp holders is gradually reduced toward the side clamp holder; the lateral arm of the elastic member can be slightly bent and fixed in shape by the force exerting on the elastic member, after being fixed in shape, the elastic variable thereof is fixed for firmly holding by clamping; the detent means can prevent cracking of the main body of the heat source due to an overly large clamping force, and can largely increase the extent of application of the detent means in mating with any of various main bodies of heat sources and heat sinks of different thickness.

Abstract: A computer heat sink, it especially suits heat sinking of various chip sets or processors which may generate high temperature during running, and has the effect of better efficiency of heat sinking and inexpensiveness of production. It includes many heat sinking fins on the periphery of a base which has centrally a receiving space for fixing a fan, when the air flow generated during running of the fan passes through the gaps among the fins, heat exchanging is induced between the air and the fins to effect heat sinking.

Abstract: A securing equipment for a heat dissipater of a CPU includes a holed main body, and a movable element. The heat dissipater is positioned in a holding member for the bottom to abut the top of the CPU. The main body has rear hooks separably connected to rear holes of the holding member. The movable element includes a control part, and a front part having up-sticking portions pivoted to the upper portion of the control part. The lower portion of the control part is pivoted to the front of the main body so as to be pivotable between a vertical position where the up-sticking portions stand upright in a locking position and a horizontal position where the up-sticking portions is in a sloping unlocking position. The front part of the movable element is further formed with hooks, which engage front holes of the holding member when the up-sticking portions stand upright in the locking position, so as to cause the main body to be pressed against the tops of the radiating fins of the heat dissipater.