Abstract: A resonant half-bridge flyback power converter includes: a first transistor and a second transistor which form a half-bridge circuit; a transformer and a resonant capacitor connected in series and coupled to the half-bridge circuit; and a switching control circuit configured to generate a first driving signal and a second driving signal to control the first transistor and the second transistor respectively for switching the transformer to generate an output voltage. The first driving signal is configured to magnetize the transformer. The second driving signal includes at most one pulse between two consecutive pulses of the first driving signal. The switching control circuit generates a skipping cycle period when an output power is lower than a predetermined threshold. A resonant pulse of the second driving signal is skipped during the skipping cycle period. The skipping cycle period is increased in response to the decrease of the output power.

Abstract: A resonant half-bridge flyback power converter includes: a first transistor and a second transistor which form a half-bridge circuit; a transformer and a resonant capacitor connected in series and coupled to the half-bridge circuit; and a switching control circuit configured to generate a first driving signal and a second driving signal to control the first transistor and the second transistor respectively for switching the transformer to generate an output voltage. The first driving signal is configured to magnetize the transformer. The second driving signal includes at most one pulse between two consecutive pulses of the first driving signal. The switching control circuit generates a skipping cycle period when an output power is lower than a predetermined threshold. A resonant pulse of the second driving signal is skipped during the skipping cycle period. The skipping cycle period is increased in response to the decrease of the output power.

Abstract: A half-bridge flyback power converter: a first transistor, a second transistor and a third transistor which form a half-bridge circuit. The first transistor is turned on for generating a negative circulated current for achieving zero voltage switching of the second transistor. The second transistor is turned on for magnetizing a transformer. The third transistor is turned on during a demagnetized time period to generate an output voltage. The physical size of the first transistor is smaller than physical size of the third transistor.

Abstract: A flyback power converter includes: a first transistor switching a transformer for generating a primary switching current and an output voltage; and a second transistor generating a circulated current to achieve ZVS (zero voltage switching) of the first transistor; wherein the flyback power converter actively forces at least one switching cycle to be operated in a DCM (discontinuous conduction mode) operation when the primary switching current is determined to have been operating in a non-DCM operation for a predetermined number of switching cycles. The flyback power converter generates a demagnetized signal which emulates the demagnetized time of the transformer for controlling the second transistor during the non-DCM operation. The flyback power converter calibrates the demagnetized signal according to the demagnetized time during the actively fored DCM operation.

Abstract: A patch having expansion and supporting effects, comprising a body (10, 10A, 10B), at least one first support member (20, 20A, 20B), and at least one second support member (30, 30A, 0B).

Abstract: A patch having expansion and supporting effects, comprising a body (10, 10A, 10B), at least one first support member (20, 20A, 20B), and at least one second support member (30, 30A, 0B).

Abstract: A body cavity illumination apparatus has a position-controlling trocar and an intra-corporeal light element. The position-controlling trocar has a sticker, a positioning device, a trocar tube, and a trocar connector. The sticker has a through hole. The positioning device is deposited on the sticker. The trocar tube is connected to the positioning device, extends through the sticker, and has an inner end and an outer end. The trocar connector is connected to the outer end of the trocar tube. The intra-corporeal light element is detachably mounted in the position-controlling trocar and has a shaft, a shaft connector, a cable connector, and a light cable. The positioning-controlling trocar may provide a holding effect to the intra-corporeal light element without manual holding to keep the position. In use, the intra-corporeal light element may provide an intra-corporeal illumination effect at multi-angles.

Abstract: A rib belt has a dragging belt and two patches. The dragging belt is length adjustable and has two opposite ends. The two patches are respectively connected to the two opposite ends of the dragging belt. Each one of the two patches has an adhesive face. The dragging belt drags the two patches in a stretching manner to resist a contracting force caused by muscle contraction.

Abstract: A body cavity illumination apparatus has a position-controlling trocar and an intra-corporeal light element. The position-controlling trocar has a sticker, a positioning device, a trocar tube, and a trocar connector. The sticker has a through hole. The positioning device is deposited on the sticker. The trocar tube is connected to the positioning device, extends through the sticker, and has an inner end and an outer end. The trocar connector is connected to the outer end of the trocar tube. The intra-corporeal light element is detachably mounted in the position-controlling trocar and has a shaft, a shaft connector, a cable connector, and a light cable. The positioning-controlling trocar may provide a holding effect to the intra-corporeal light element without manual holding to keep the position. In use, the intra-corporeal light element may provide an intra-corporeal illumination effect at multi-angles.

Abstract: A circuit for driving a light source includes a power converter coupled between a power source and the light source, and a controller coupled to the power converter. The power converter receives power from the power source and provides a regulated power to the light source. The controller receives a conduction status signal indicating a conduction state of a dimmer coupled between the power source and the power converter, and adjusts the brightness of the light source based on the conduction status signal. The controller also receives an operation indicating signal indicative of operation of an ON/OFF switch coupled to the dimmer, and adjusts color temperature of the light source based on the operation indicating signal.

Abstract: A switching power supply includes a power converter which includes a transformer and a switch, a current sensor, a switch controller and a compensation resistor. The current sensor is operable for generating a current monitoring signal indicating a current through a primary winding of the transformer. The switch controller is operable for receiving a feedback signal indicating an output voltage of the power converter, generating a driving signal based on the feedback signal to control an input power and an output power of the transformer, receiving a line voltage signal indicating an input voltage of the power converter, and generating a compensation current corresponding to a peak value of the line voltage signal. The compensation resistor is coupled between the current sensor and the switch controller. A voltage of the current monitoring signal is inversely proportional to the input voltage under control of the compensation current and the compensation resistor.

Abstract: A switching power supply includes a power converter which includes a transformer and a switch, a current sensor, a switch controller and a compensation resistor. The current sensor is operable for generating a current monitoring signal indicating a current through a primary winding of the transformer. The switch controller is operable for receiving a feedback signal indicating an output voltage of the power converter, generating a driving signal based on the feedback signal to control an input power and an output power of the transformer, receiving a line voltage signal indicating an input voltage of the power converter, and generating a compensation current corresponding to a peak value of the line voltage signal. The compensation resistor is coupled between the current sensor and the switch controller. A voltage of the current monitoring signal is inversely proportional to the input voltage under control of the compensation current and the compensation resistor.

Abstract: A driving circuit for driving a light source having an adjustable color temperature is provided. The driving circuit includes a power converter, coupled between a power source and the light source and operable for receiving power from the power source and for providing a regulated power to the light source; and a color temperature controller, coupled to the power converter and operable for receiving a switch monitoring signal indicative of an operation of a power switch coupled between the power source and the power converter, and for adjusting the color temperature of the light source based on the switch monitoring signal.

Abstract: An illuminated surgical retractor system includes a surgical retractor and at least one illumination device. The surgical retractor includes an outer ring, a light-transmissive hollow inner ring, and a tubular retraction membrane which extends between the output ring and the inner ring and which has a first open end connected to and spread open by the outer ring and a second open end connected to and spread open by the inner ring. The illumination device is disposed in the inner ring and is operable to emit a light beam. The illumination device includes a magnetic component which is responsive to an applied magnetic field to cause the illumination device to change a direction in which the light beam is emitted.

Abstract: A control circuit and a method for controlling a power converter are provided. The method for controlling the power converter includes the following steps. A detection signal is received from the secondary side of the power transformer and a first switching signal is generated in accordance with the detection signal. A second switching signal is generated in accordance with the first switching signal. A voltage signal is generated in accordance with the second switching signal. A comparison signal is generated in accordance with the first switching signal and the second switching signal. The voltage signal and the comparison signal are compared for outputting a comparison result. A gate signal is generated in accordance with the detection signal and the comparison result to control on and off states of a synchronization switch.

Abstract: A circuit for driving a light source includes a power converter coupled between a power source and the light source, and a controller coupled to the power converter. The power converter receives power from the power source and provides a regulated power to the light source. The controller receives a conduction status signal indicating a conduction state of a dimmer coupled between the power source and the power converter, and adjusts the brightness of the light source based on the conduction status signal. The controller also receives an operation indicating signal indicative of operation of an ON/OFF switch coupled to the dimmer, and adjusts color temperature of the light source based on the operation indicating signal.

Abstract: An illuminated surgical retractor system includes a surgical retractor and at least one illumination device. The surgical retractor includes an outer ring, a light-transmissive hollow inner ring, and a tubular retraction membrane which extends between the output ring and the inner ring and which has a first open end connected to and spread open by the outer ring and a second open end connected to and spread open by the inner ring. The illumination device is disposed in the inner ring and is operable to emit a light beam. The illumination device includes a magnetic component which is responsive to an applied magnetic field to cause the illumination device to change a direction in which the light beam is emitted.

Abstract: A synchronous rectifying circuit for a switching power converter is provided. The synchronous rectifying circuit includes a power transistor, a diode, and a control circuit. The power transistor and the diode are coupled to a transformer and an output of the power converter for rectification. The control circuit generates a drive signal to switch on the power transistor once the diode is forward biased. The control circuit includes a monitor circuit. The monitor circuit generates a monitor signal an off signal to switch off the power transistor in response to a pulse width of the drive signal for generating an off signal to switch off the power transistor. The monitor circuit further reduces the pulse width of the drive signal in response to a change of a feedback signal. The feedback signal is correlated to an output load of the power converter.

Abstract: A dual switches Flyback power converter with a wide input voltage range according to the present invention comprises an input diode and an energy-storage capacitor. The input diode can prevent the reflected voltage from the power transformer of the power converter to charge the electrolytic capacitor of the power converter. The energy-storage capacitor will store the reflected voltage and the energy of the leakage inductor of the power transformer. The energy stored in the energy-storage capacitor will be recycled to the output voltage of the power converter. Further, the input diode can be replaced by an input transistor to prevent the reflected voltage from the power transformer to charge the electrolytic capacitor.

Abstract: An exemplary embodiment of a power converter is provided. The power converter includes a transformer, a power device, a switching controller, and a capacitor. The power device is coupled to the transformer for switching the transformer to product output of the power converter. The switching controller receives a feedback signal for generating a switching signal coupled to drive the power device. An input circuit of the switching controller is coupled to the transformer to sample an input signal for generating the feedback signal, and the input signal is correlated to the output of the power converter. The capacitor is coupled to the switching controller to provide frequency compensation for a feedback loop of the power converter. Input of the power converter is without an electrolytic capacitor, and a maximum output current of the power converter is a constant current.