1666 results about "Duty cycling" patented technology

A light emitting diode (LED) lighting system includes a controller to control current in one or more LEDs in response to a dimming level input. The LED lighting system implements a dimming strategy having two modes of operation that allow the LED lighting system to dim the LEDs using an active value of an LED current less than a full value LED current while maintaining continuous conduction mode operation. In an active value varying mode of operation, the controller varies an active value of the LED current for a first set of dimming levels. In an active value, duty cycle modulation mode of operation, the controller duty cycle modulates an active value of the LED current for a second set of dimming levels. In at least one embodiment, the active value of the LED current varies from a full active value to an intermediate active value as dimming levels decrease.

A buck-boost switching regulator includes two buck switches and two boost switches. Two ramp voltages VY and VY are generated. The voltage VY is compared to a voltage VEA1 that is proportional to the output of the switching regulator. This defines the duty cycle of the two buck switches. The voltage VX is compared to a voltage VEA2 that is inversely proportional to the output of the switching regulator. This defines the duty cycle of the two boost switches. The regulator seamlessly transitions between Buck, Boost and Buck-Boost modes depending on input and output conditions.

A device for heating or cooling a body of a user is provided. The device includes a thermoelectric module, a heat sink thermally coupled to the thermoelectric module, a wetting material in thermal communication with the heat sink, and a controller for cycling the thermoelectric module in accordance with a duty cycle. Additionally, a method of heating or cooling a portion of a body of a user is provided. The method includes cycling electrical power to a thermoelectric module at a duty cycle, transferring heat from the thermoelectric module to a heat sink, and evaporating a liquid from a wetting material disposed on the heat sink. The evaporated liquid enters the surrounding atmosphere.

A method is presented for enabling radio-frequency (RF) communications between an implantable medical device and an external device in a manner which reduces the power requirements of the implantable device by duty cycling its RF circuitry. A wakeup scheme for the implantable device is provided in which the external device transmits a data segment containing a repeating sequence of special wakeup characters and a device ID in order to establish a communications session with the implantable device. The wakeup scheme may be designed to operate using multiple communications channels.

A fixing device includes a fuser member, a heater, a thermometer, and a power supply controller. The fuser member is subjected to heating. The heater is adjacent to the fuser member to heat the fuser member. The thermometer is adjacent to the fuser member to detect an operational temperature of the fuser member. The power supply controller controls power supply to the heater by adjusting a duty cycle. The controller includes a duty cycle calculator, a driver circuit, and a duty cycle modifier. The duty cycle calculator is operatively connected to the thermometer to calculate a primary value of the duty cycle based on the operational temperature. The driver circuit is operatively connected to the duty cycle calculator to supply power to the heater according to the duty cycle. The duty cycle modifier is connected between the duty cycle calculator and the driver circuit to modify the duty cycle.

Provision is made in the housing of a host to provide a socket, or sockets, to which a peripheral piece of equipment can be connected for receiving directly from the host the low voltage DC power it requires. The socket(s) are connected electrically to the outputs of a power supply (or regulator) of a host for providing the low voltage needed to power the peripheral. The power supply may be mounted on the rear face of a computer. The principal feature of the invention resides in the use of a connector for connecting the host DC power to the peripheral DC power usage device. The connector comprises pins connected to a selected resistor in the power supply. The resistor value (i.e., resistance) is selected to produce a pre-determined control voltage which is fed back to a DC to DC converter in the host's internal power supply. The converter comprises a pulse width modulation control device. The control voltage determines the duty cycle (i.e., pulse width) of the modulation to reduce the output from a maximum voltage to an appropriate voltage suitable for the particular peripheral power usage device. Thus, by simply selecting the appropriate connector (or cable) having the proper pins correlated to a selected resistor previously installed in the power supply, the voltage level for the corresponding peripheral device is automatically selected. In an alternative embodiment, the DC power distribution apparatus of the present invention comprises a stand-alone unit having one or more universal ports for receiving a cable with a connector containing the appropriate pins for a selected DC power usage device.

A sag corrector apparatus for providing voltages temporarily (ride-through) to a load during momentary electrical disturbances in the power supply line. In one embodiment, the disclosed apparatus compensates for voltage sags by using a variable duty cycle boost converter to boost the sagged line voltage to resemble desired voltage levels during occurrence of voltage sags. The boosted voltage available to a connected load during a sag depends on a sequence of operation of various control pulses. Duty cycle of the boost converter is controlled by changing the width (duration) of the control pulses. To prevent voltage shoot-throughs from over-boosting, an energy clamp circuit is provided to dissipate excess energy. Embodiments of the sag corrector circuit can be additionally integrated with power protection functions.

Systems and methods are provided for compensating for variations in line voltages the power an electro-kinetic air transporter and conditioner device. The electro-kinetic air transporter and conditioner device includes a high voltage generator that provides a potential difference between at least one emitter electrode and at least one collector electrode. The high voltage generator is driven by both a DC voltage obtained from an AC voltage source, and a low voltage pulse signal. The DC voltage is stepped down to produce a voltage sense signal indicative of a level of AC voltage source. The voltage sense signal is monitored. At least one of a pulse width, duty cycle and frequency of the low voltage pulse signal is adjusted, based on the monitored voltage sense signal, in order to substantially maintain the potential difference at a desired level.