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: A tracheal tube includes an airway tubular body, an inflatable cuff disposed on the airway tubular body, a suction conduit extending along the airway tubular body to terminate at a suction opening, and a guiding unit disposed on the airway tubular body and adjacent to the suction opening. The guiding unit includes at least one guiding member having a plurality of ribs. Each two adjacent ones of the ribs define a guiding groove that extends toward the suction opening and that terminates at a confluent region in fluid communication with the suction opening so as to guide secretions in the trachea to the suction opening.

Abstract: A device adapted for insertion into one or more of an esophagus, a stomach, an intestine and a colon for detecting a blood-oxygen level associated with at least one mucous membrane region in said one or more of the esophagus, the stomach, the intestine and the colon is disclosed. The device includes a flexible and elongated main body, and a blood oxygen level detecting unit. The blood oxygen level detecting unit includes one or more blood oxygen level detecting modules disposed on the main body and capable of generating one or more signals associated with the blood oxygen level(s) of one or more mucous membrane regions nearby the blood oxygen level detecting module(s).

Abstract: A surgical retractor includes an outer ring unit, a tubular retraction membrane made of a resilient material and including an inner surface defining a passageway, and a lighting unit. The tubular retraction membrane has an outer tubular end connected to the outer ring unit and rollable about the outer ring unit. The lighting unit is connected to an inner tubular end of the retraction membrane and includes a light-emitting ring, and a heat-dissipation ring in contact with the light-emitting ring.

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 control circuit for a switching power converter is provided. The control circuit is installed between a secondary side and an output of the power converter and coupled to control a switching device. The control circuit includes a linear predict circuit, a reset circuit, a charge/discharge circuit, and a PWM circuit. The linear predict circuit is coupled to receive a linear predict signal from the secondary side for generating a charging signal. The reset circuit is couple to receive a resetting signal for generating a discharging signal. The charge/discharge circuit is coupled to receive the charging signal and the discharging signal for generating a ramp signal. The PWM circuit is coupled to receive the linear predict signal for enabling a switching signal and receive the ramp signal for resetting the switching signal.

Abstract: An adaptive synchronous rectification control circuit and a control method are developed. The control circuit comprises an adaptive circuit that generates a reference signal in response to a detection signal of a power converter. A clamped circuit clamps the reference signal at a threshold voltage if the reference signal equals or is greater than the threshold voltage. A switching circuit generates a control signal to control a synchronous switch of the power converter in response to the detection signal and the reference signal. The control method generates the reference signal in response to the detection signal. The reference signal is clamped at the threshold voltage if the reference signal equals or is greater than the threshold voltage. The method further generates the control signal to control the synchronous switch of the power converter in response to the detection signal and the reference signal.

Abstract: A switching control circuit for a switching power converter is provided. The switching control circuit is coupled to a switching device and an auxiliary winding of a transformer. The switching control circuit includes a valley detecting circuit, a valley lock circuit, and a PWM circuit. The valley detecting circuit is coupled to receive a reflected voltage signal from the auxiliary winding of the transformer for outputting a control signal in response to the reflected voltage signal. The valley lock circuit is coupled to receive the control signal for outputting a judging signal in response to the control signal during a first period and a second period following the first period. The PWM circuit outputs a switching signal in response to the judging signal.

Abstract: An adjustable office chair includes a base device, and a seat device disposed on the base device. The seat device includes a fixed seat section, a rear seat section connected pivotally to and disposed behind the fixed seat section, a front seat section connected pivotally to and disposed in front of the fixed seat, and an invertible seat section connected pivotally to a side of the front seat section distal from the fixed seat section. The invertible seat section is movable to a position directly above the fixed seat section to allow a user to sit thereon. The front and invertible seat sections are movable to align with the fixed seat section to allow the user to sit on the fixed seat section. The rear seat section is movable to an inclined position to allow the user to lie on the seat device.

Abstract: An exemplary embodiment of a flyback power converter includes a transformer for power transfer, a high-side transistor, a low-side transistor, two diodes, a control circuit, and a high-side drive circuit. The high-side transistor and the low-side transistor are coupled to switch the transformer. The two diodes are coupled to said transformer to circulate energy of leakage inductance of the transformer to an input power rail of the power converter. The control circuit generates a switching signal coupled to control the high-side transistor and the low-side transistor. The high-side drive circuit is coupled to receive the switching signal for driving the high-side transistor. The transformer has an auxiliary winding generating a floating power to provide power supply for said high-side drive circuit.

Abstract: A surgical retractor includes an outer ring unit, a tubular retraction membrane made of a resilient material and including an inner surface defining a passageway, and a lighting unit. The tubular retraction membrane has an outer tubular end connected to the outer ring unit and rollable about the outer ring unit. The lighting unit is connected to an inner tubular end of the retraction membrane and includes a light-emitting ring, and a heat-dissipation ring in contact with the light-emitting ring.

Abstract: A combined retractor and endoscope system includes a retraction ring and an endoscope unit. The retraction ring includes a tubular inner surface defining a passageway. The endoscope unit includes a flexible arm that can be positioned stably and moved between an edge of an incision and an outer peripheral surface of the retraction ring, and a camera attached to one end of the flexible arm. In a preferred embodiment, the flexible arm has a flexible outer tube body incorporating a support strip that can be bent together with the outer tube body to retain a bent configuration of the outer tube body.

Abstract: An adjustable office chair includes a base device, and a seat device disposed on the base device. The seat device includes a fixed seat section, a rear seat section connected pivotally to and disposed behind the fixed seat section, a front seat section connected pivotally to and disposed in front of the fixed seat, and an invertible seat section connected pivotally to a side of the front seat section distal from the fixed seat section. The invertible seat section is movable to a position directly above the fixed seat section to allow a user to sit thereon. The front and invertible seat sections are movable to align with the fixed seat section to allow the user to sit on the fixed seat section. The rear seat section is movable to an inclined position to allow the user to lie on the seat device.

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.

Abstract: A control circuit for a switching power converter is provided. The control circuit is installed between a secondary side and an output of the power converter and coupled to control a switching device. The control circuit includes a linear predict circuit, a reset circuit, a charge/discharge circuit, and a PWM circuit. The linear predict circuit is coupled to receive a linear predict signal from the secondary side for generating a charging signal. The reset circuit is couple to receive a resetting signal for generating a discharging signal. The charge/discharge circuit is coupled to receive the charging signal and the discharging signal for generating a ramp signal. The PWM circuit is coupled to receive the linear predict signal for enabling a switching signal and receive the ramp signal for resetting the switching signal.

Abstract: A control circuit is developed to adaptively operate a power converter at quasi-resonance (QR) and in a continuous current mode (CCM) to achieve high efficiency. The control circuit includes a PWM circuit generating a switching signal coupled to switch a transformer. A signal generation circuit generates a ramp signal and a pulse signal. The pulse signal is generated in response to the ramp signal for switching on the switching signal. A feedback circuit produces a feedback signal according to an output load of the power converter. The feedback signal is coupled to switch off the switching signal. A detection circuit is coupled to the transformer for generating a valley signal in response to the waveform of the transformer. The valley signal is further coupled to generate the pulse signal when the ramp signal is lower than a threshold. The level of the threshold is correlated to the feedback signal.

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-store 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-store capacitor will store the reflected voltage and the energy of the leakage inductor of the power transformer. The energy stored in the energy-store 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 adaptive synchronous rectification control circuit and a control method are developed. The control circuit comprises an adaptive circuit that generates a reference signal in response to a detection signal of a power converter. A clamped circuit clamps the reference signal at a threshold voltage if the reference signal equals or is greater than the threshold voltage. A switching circuit generates a control signal to control a synchronous switch of the power converter in response to the detection signal and the reference signal. The control method generates the reference signal in response to the detection signal. The reference signal is clamped at the threshold voltage if the reference signal equals or is greater than the threshold voltage. The method further generates the control signal to control the synchronous switch of the power converter in response to the detection signal and the reference signal.

Abstract: A switching control circuit for a switching power converter is provided. The switching control circuit is coupled to a switching device and an auxiliary winding of a transformer. The switching control circuit includes a valley detecting circuit, a valley lock circuit, and a PWM circuit. The valley detecting circuit is coupled to receive a reflected voltage signal from the auxiliary winding of the transformer for outputting a control signal in response to the reflected voltage signal. The valley lock circuit is coupled to receive the control signal for outputting a judging signal in response to the control signal during a first period and a second period following the first period. The PWM circuit outputs a switching signal in response to the judging signal.

Abstract: An active clamp circuit for a QR flyback power converter according to the present invention comprises an active-clamper connected to a primary winding of a power transformer of the QR flyback power converter in parallel. A high-side transistor driver is coupled to drive the active-damper. A charge-pump circuit is coupled to the high-side transistor driver to provide a power supply to the high-side transistor driver in accordance with a voltage source. A control circuit generates a control signal coupled to control the high-side transistor driver. The control signal is generated in response to a PWM signal and an input voltage of the QR flyback power converter.