9476 results about "Voltage drop" patented technology

A motor controller includes a power source unit providing a direct current output, a drive unit including a drive coil, first and second transistor units, a voltage drop component, and a processor. The transistor units are coupled to the power source unit and the drive unit, and enable electricity to flow through the drive coil in a first direction when the first and the second transistor units are in conducting and non-conducting states respectively, and in an opposite second direction when the first and the second transistor units are in non-conducting and conducting states respectively. The voltage drop component has a first end coupled to the drive unit and a grounded second end. The processor is coupled to a junction of the drive unit and the voltage drop component, and provides first and second pulse-width-modulated signals to the first and second transistor units, respectively.

A circuit for a lighting device comprises a sub-circuit which comprises a series current regulator and a group of solid state light emitters. The current regulator and the solid state light emitters are arranged in series. In some embodiments, the circuit further comprises a fan electrically connected in series in the sub-circuit. In some embodiments, the circuit further comprises a second sub-circuit which comprises a second series current regulator and a second group of solid state light emitters, the first sub-circuit and the second sub-circuit being arranged in parallel. In some embodiments, an anode of the series current regulator is electrically connected to a cathode of one of the solid state light emitters. Also, methods of lighting wherein a sum of voltage drops across light emitters and a current regulator is in the range of from 1.2 to 1.6 times the line voltage.

A fault detection mechanism for a LED string comprising a plurality of serially connected LEDs, the fault detection mechanism comprising: a control circuitry; and a voltage measuring means, in communication with the control circuitry, arranged to measure the voltage drop across at least one LED of the LED string, the control circuitry being operable to: measure the voltage drop, via the voltage measuring means, at a plurality of times, compare at least two of the measured voltage drops, and in the event the comparison of the at least two voltage drops is indicative of one of a short circuit LED and an open circuit LED, output a fault indicator.

A light-emitting diode (LED) driver according to the present invention consists of a voltage pre-regulator and multiple linear current regulators with an adaptively-controlled drive voltage. In this LED driver, the efficiency maximization is achieved by eliminating the sensing of the voltage drops across the linear regulators, i.e., by removing the external voltage feedback for the adjustment of the output voltage of the pre-regulator. In the LED driver of the present invention, the self-adjustment of drive voltage is achieved by relying on a relatively strong dependence between the gate-to-source and drain-to-source voltages of a current-regulating transistor, e.g., a MOSFET, operating in the linear region. The driver powers all LEDs in a string with a constant current and provides consistent illumination and optimum operating efficiency at low cost over a wide range of input/output voltage and temperature.

An active matrix electroluminescent display device has a current sampling resistor within each pixel in series with the display element. A feedback signal represents the voltage drop across the current sampling resistor and the pixel drive signals are modified in dependence on the feedback signal to control the current driven through the display element. In this way, threshold compensation is provided, whilst enabling a single voltage-driven drive transistor to be employed.

A current-mode switching regulator uses adaptive current sensing to reliably monitor an inductor current in a cost-efficient and power-efficient manner. A semiconductor switch periodically turns on to conduct the inductor current. A voltage drop across the semiconductor switch is monitored when the semiconductor switch is on. A variable gain amplifier with an automatic gain control loop generates a feedback signal from the voltage drop of the semiconductor switch when conducting to provide an indication of the inductor current to a controller. The automatic gain control loop compensates for any variations in the on-resistance of the semiconductor switch.

The present invention provides an image display device that reduces variations in brightness of the light emitting elements included in the device due to a voltage drop on the power source line of the device and TFT threshold voltage variations and displays good quality images. The image display device is equipped with a pixel circuit voltage detecting means to selectively output a voltage internal to a pixel circuit included in each of a plurality of pixels of the device to a signal line to which the pixel circuit connects. Its drive circuit is equipped with a voltage addition means to add the signal line voltage and a signal voltage corresponding to image data to be displayed and output a sum voltage to the signal line again.

A drive circuit of a display device, which comprise only single conductive TFTs and in which amplitude of an output signal is normal, is provided. A pulse is inputted to TFTs 101 and 104 so that the TFTs would turn ON and then potential of a node á rises. When the potential of the node á reaches (VDD-VthN), the node á became in a floating state. Accordingly, a TFT 105 then turns ON, and potential of an output node rises as a clock signal reaches the level H. On the other hand, potential of a gate electrode of the TFT 105 further rises due to an operation of capacitance 107 as the potential of the output node rises, so that the potential of the output node would be higher than (VDD+VthN). Thus, the potential of the output node rises to VDD without voltage drop caused by a threshold of the TFT 105. An output at the subsequent stage is then inputted to TFTs 102 and 103 to turn the TFTs 102 and 103 ON, while the potential of the node á drops down to turn the TFT 105 OFF. A TFT 106 turns ON at the same time so that the potential of the output node would reach the level L.

A method is provided for tracking an object, including positioning a radio frequency (RF) driver to radiate an RF driving field toward the object, and fixing to the object a wireless transponder that includes a power coil and at least one sensor coil. The method also includes receiving the RF driving field using the power coil and storing electrical energy derived therefrom. A plurality of field generators are driven to generate electromagnetic fields at respective frequencies in a vicinity of the object that induce a voltage drop across the at least one sensor coil. A digital output signal is generated at the wireless transponder indicative of the voltage drop across the sensor coil, and the generation of the digital output signal is powered using the stored electrical energy. The digital output signal is transmitted from the wireless transponder using the power coil, and the transmission of the digital output signal is powered using the stored electrical energy. The digital output signal is received and processed to determine coordinates of the object.

A battery voltage Ef of a fuel cell 1 is detected, and a current instruction value which transformed an electric power instruction value Pfc of the fuel cell is reduced at falling-down of the voltage Ef. A current limiter 8 makes the current instruction value a limit value at the time of the falling-down of Ef, and reduces the limit value according to the fall of Ef. For example, current instruction value is restricted so as to begin to reduce battery current IFC at voltage drop alarm level (first threshold value), and become zero at voltage drop protection level (second threshold value).

An improved switching regulator for implantable medical devices includes a control circuit with a capacitor divider to conserve energy, and selectable duty cycles to efficiently match the duty cycle to the charge level in a holding capacitor. The switching regulator charges the holding capacitor to commanded voltage levels, and the holding capacitor provides current for tissue stimulation. The commanded voltage level is reached by “pumping-up” the holding capacitor with the output of the switching regulator. For control purposes, the high voltage (i.e., the voltage across the holding capacitor) is divided between a fixed capacitor and a variable capacitor, and the voltage between the fixed capacitor and the variable capacitor (i.e., the divided voltage) is compared to a reference voltage. The result of the comparison is used to turn-off the switching regulator once the commanded voltage level is reached. The switching duty cycle is set to one of two values. At start-up, or when the output voltage drops below a determined threshold, a low duty cycle is used. Once the output voltage reaches the threshold, a higher duty cycle is used.

A power supply including a regulation circuit that maintains an approximately constant load current with line voltage. An example circuit includes a switch including first, second and third terminals. The first terminal is coupled or decoupled to the second terminal in response to a control signal received at the third terminal. Voltage sense circuitry is included and is coupled to sense a voltage drop across the switch. The voltage drop is representative of a current in the switch during an on time of the switch. The voltage sense circuitry has a variable current limit threshold that increases between a first level and a second level during the on time of the switch. The control signal is responsive to the variable current limit threshold to regulate a power supply with an output characteristic having an approximately constant output voltage below an output current threshold and an approximately constant output current below an output voltage threshold.

A constant voltage/constant power AC adapter converts AC voltage to DC voltage to provide power to a plurality of loads. The adapter's output characteristic is approximately a constant voltage as long as the output current draw by the loads is less than a threshold (e.g. a safety threshold for the adapter). If, however, the power draw on the adapter is such that the output current exceeds the threshold, the adapter then decreases its output voltage to maintain the power draw at a safe level. One or more loads that draw power from the adapter may be adapted to detect a drop in the AC adapter's output voltage. When such a voltage drop is detected, that information tells the load that too much current is being drawn from the adapter and that the load should throttle back (e.g., reducing battery charge current, CPU clock frequency, display brightness, etc.).

This invention generally relates to methods, apparatus and computer program code for improved OLED (organic light emitting diode) display drive systems, in particular to compensate for burn-in.

A method of compensating an OLED display device for burn-in of pixels of the OLED display, the method comprising: measuring a first voltage drop across at least one test pixel of the display; measuring a second voltage drop across at least one other pixel of the display; determining, from said first and second voltages and a from value (V₁) representing a drive voltage increase for a loss in efficiency of said display due to burn-in, an estimated reduction in efficiency of said display due to burn-in; and compensating a drive to said display using said estimated efficiency reduction.

A primary-side flyback power converter supplies a constant voltage and a constant current output. To generate a well-regulated output voltage under varying load conditions, the power converter includes a PWM controller. The PWM controller generates a PWM signal to control a switching transistor in response to a flyback voltage detected from the first primary winding of the power supply transformer. To reduce power consumption, the flyback energy of the first primary winding is used as a DC power source for the PWM controller. The flyback voltage is sampled following a delay time to reduce interference from the inductance leakage of the transformer. To generate a more accurate DC output voltage, a bias current is pulled from the detection input to form a voltage drop across a detection resistor for compensating for the voltage drop of the output rectifying diode.

A silicon-on-insulator (SOI) electrostatic discharge (ESD) protection device that can protect very sensitive thin gate oxides by limiting the power dissipation during the ESD event, which is best achieved by reducing the voltage drop across the active (protection) device during an ESD event. In one embodiment, the invention provides very low triggering and holding voltages. Furthermore, the SOI protection device of the present invention has low impedance and low power dissipation characteristics that reduce voltage build-up, and accordingly, enable designers to fabricate more area efficient protection device.

A probe for connecting a device under test to a measurement device that corrects for dc errors and noise generated by the current flowing through the ground shield of a transmission line used by the probe. The probe identifies a voltage drop in the ground preferably using an additional line between the device under test and the measurement device. The signal provided to the measurement device is corrected based on the identified voltage drop.