229results about How to "Constant current" patented technology

A main power supply continuously provides a current to a power input terminal of an integrated circuit device under test (DUT). The DUT's demand for current at the power input terminal temporarily increases during state changes in synchronous logic circuits implemented within the DUT. To limit variation (noise) in voltage at the power input terminal arising from these temporary increases in current demand, a charged capacitor is connected to the power input terminal during each DUT state change. The capacitor discharges into the power input terminal to supply additional current to meet the DUT's increased demand. Following each DUT state change the capacitor is disconnected from the power input terminal and charged to a level sufficient to meet a predicted increase in current demand during a next DUT state change.

In a tomography apparatus and a method for operating a tomography apparatus for generation of multiple energy images, in which high-energy projections and low-energy projections are acquired by alternating adjustment of a voltage and a further control variable (namely the current or the exposure time), given a set first voltage value and a set first control value of the further control variable, and given a set second voltage value and a set second control value of the further control variable, x-rays generated by an x-ray radiator exhibit essentially the same x-ray dose or photon flow.

The invention belongs to the technical field of light source illuminating and electronics, in particular relates to an intelligent general light-emitting diode (LED) street lamp illuminating power supply system. The system comprises an input surge protection and electromagnetic interference suppressing circuit, a BOOST-BUCK isolation backlash power factor correction switch power circuit, an LED chip temperature detection circuit, an ambient brightness detection circuit, a permanent calendar chip, a peripheral circuit, an LED failure detection circuit, a singlechip circuit and a constant-current output control circuit. In the switch power circuit of the invention, a circuit structure is simplified and circuit efficiency is improved based on an active power factor correction (PFC) control chip L6562,; and the singlechip circuit monitors the ambient brightness, the temperature of the LED chip, time and LED fault in real time by taking a chip STC12C5606AD as a control core and intelligently adjusts the output brightness of the LED according to different situations, so that energy is saved and the service life of an LED street lamp is prolonged effectively at the same time.

A high efficiency power drive device enabling serial connection of LED lamps thereto, which includes a power source filter circuit, an AC to DC rectifier, a power factor correction circuit and an LED constant current drive circuit. The power factor correction circuit is utilized using the so-called transition mode technique to obtain voltage required by the LED lamps when serially connected, and current control is used to achieve a state whereby the current and voltage are in the same phase. A current control IC and an externally set resistor are further used to eliminate the need to adopt any CPU (central processing unit) while accurately directly controlling the output pulse width of PWM (Pulse Width Modulation).

The invention discloses an LED (light emitting diode) constant current driving circuit with current detection and an LED backlight system. The LED constant current driving circuit with current detection comprises a reference voltage module, a reference current generating module, an output current control module, an output current and output end voltage detection module and a PWM (pulse width modulation) control signal generating module. According to the invention, the control signal duty cycle of a switching tube is adjusted by feeding back the minimum current in LED light string so as to drive LED light string by constant current. Meanwhile, the current and output voltage of the LED light string is detected to judge whether the LED light string undergoes open circuit or short circuit; and when all LED light strings have problem, the output current control module is controlled to close the current output.

The invention discloses a contact-type reliability test bed capable of conducting mixed loading on an electric main shaft. The test bed is composed of the electric main shaft, a connecting shaft unit, a torque loading device, a radial force electromagnetic loading device, an axial force electromagnetic loading device and a swing arm device. The test bed can load an axial force, a radial force and a torque on the electric main shaft at the same time, control the magnitudes of the three forces in a coordinate mode to simulate cutting forces in different magnitudes and different directions, really and reliably simulate the cutting forces of the electric shaft in practical working conditions, and provide a test foundation for reliability acceleration tests of the electric shaft.

A light engine driven directly from the AC power line has multiple series connected arrays of LEDs each with an associated current limiting transistor. The current from each current limiting transistor goes through a corresponding current sensing resistor and all these resistors are connected in series. The voltage across each current limiting transistor is applied across the next LED array so that as the voltage increases during the power line cycle, the next array becomes activated by the increasing voltage across the previous current limiting transistor. When this happens the previous current limiting transistor is turned off. This continues until all the arrays are activated at the peak of the line, at which point the array current is controlled by the last current limiting transistor.

The invention belongs to the technical field of electronics, and relates to an LED (light emitting diode) street lamp driving circuit capable of regulating output illuminance automatically. The driving circuit comprises an input surge protection and electromagnetic interference suppression circuit, a single-tube flyback switch power circuit with a power factor correction function, an environment illuminance detection circuit, a chip temperature detection circuit, a perpetual calendar chip, the periphery circuit of the calendar chip and an output current automatic regulation switch circuit controlled by a microcomputer; a dual-control working mode with the primary light control and auxiliary time control by the microcomputer for a general switch control module provided by the invention; and when the primary control is out of control, the auxiliary control replaces working automatically, and the light control according to the set illuminance controls the starting and closing operation of the street lamp. The driving circuit provided by the invention has the advantages of power factor correction, can regulate the output current automatically according to time, the environment illuminance and the LED chip temperature, can control the luminosity to regulate the output current directly as the control mode, and compared with the traditional low-frequency PWM (pulse width modulation) control method, the electromagnetic interference is less, and is more friendly to human eyes.

The invention discloses a tension roll control device for a plate and strip processing line and a tension control method, belonging to the field of tension control of tension rolls on the plate and strip processing line in the metallurgical industry. The tension roll control device comprises a tension roll group, an auxiliary roll frequency converter and a main roll frequency converter, and further comprises an auxiliary roll speed encoder, a main roll speed encoder, a load distributor, a tension regulator, a feedforward compensation unit and a tensiometer, wherein two ends of the load distributor are respectively connected with the auxiliary roll frequency converter and the main roll frequency converter; the auxiliary roll frequency converter comprises an auxiliary roll rotation speed control unit and an auxiliary roll torque control unit; and the main roll frequency converter comprises a main roll rotation speed control unit and a main roll torque control unit. The tension roll control device has the advantages of high control response speed and high control precision. A control method of the tension roll control device comprises the steps of: (1) main/slave load distribution for the tension rolls; (2) complex tension control of the tension rolls; and (C) dynamic compensation. The method has the advantages of small steady state error of a torque loop, short anti-disturbance recover time, constant rotation speed and good anti-disturbance performance.

A switching power supply for achieving a constant current drooping characteristic of sufficient accuracy with low cost and the minimum number of components. In the switching power supply, a secondary duty limiter circuit outputs a clock signal from the time a switching element is turned off until the time the on duty of secondary current, which starts flowing to a secondary winding of a transformer, is fixed at a predetermined value. A clock signal selector circuit selects and outputs the clock signal when a load increases and the on duty of the secondary current reaches the predetermined value. Consequently, when the load increases, a direct current output voltage decreases and an output characteristic becomes a constant current drooping characteristic. At this point, when the voltage of an element current detection signal reaches an overcurrent protection reference voltage, a drain current control circuit outputs a turn-off signal for determining the turn-off of the switching element, therefore the peak current of the secondary current is kept at a fixed value.

This disclosure provides systems, methods and apparatus for wireless power transfer and particularly wireless power transfer to remote system such as electric vehicles. In one aspect a circuit for wireless power transfer is provided. The circuit comprises an inductive element for receiving wireless power from a magnetic field associated with a wireless power transfer transmitter device. The circuit further comprises an output configured to be connected to a load. The circuit further comprises a voltage detector configured to detect the voltage across the load. The circuit further comprises at least one switching element between the inductive element and the output. The circuit further comprises a controller configured to maintain a current in the inductive element substantially constant as the voltage detected across the load varies.

A system and method for driving a LED is disclosed. The system is switched in turn between a constant-current mode circuit and a constant-voltage mode circuit. Accordingly, the forward voltage of the LED could be maintained constant, and the efficiency in power consumption could be substantially increased.

The invention provides an intelligent traffic isolation device which is characterized by comprising a plurality of automatic lifting columns, each automatic lifting column comprises an insulating box body mounted and embedded under the surface, a hollow insulating sleeve is arranged in the insulating box body and is fixedly connected with a bottom plate of the insulating box body, a lifting column body is movably sheathed inside a hollow cavity of the insulating sleeve, the bottom end of the lifting column body is an iron column, the upper end is anti-collision rubber, the outer surface of the iron column is connected with an electrified coil in a winding way, a permanent magnet corresponding to the iron column is arranged in the insulating sleeve, and a spring is connected between the bottom plate of the insulating box body and the lifting column body. When the lifting column body extends out of the surface, the iron column is positioned under the surface. The intelligent traffic isolation device provided by the invention can control and automatically regulate the quantity of lanes in the up-and-down direction and solve the road congestion problem occurring in specific time periods at a lower cost.

The invention discloses a pixel circuit of an active organic electroluminescent display. The pixel circuit comprises a first transistor, a second transistor, a third transistor, a fourth transistor, a fifth transistor, an organic lighting emitting diode, a first capacitor and a second capacitor. The invention further discloses a programming method of the pixel circuit of the active organic electroluminescent display. The programming method includes that in the first frame period, programming includes stages of initializing, threshold voltage latch, data loading and lighting of the organic light emitting diode; in continuous N frame periods from the second frame, programming only includes stages of data loading and lighting of the organic light emitting diode; and repeating the above process consecutively and circularly. In case of threshold voltage drift of the driving transistor and ageing of the organic light emitting diode, current of the organic light emitting diode is always kept constant, and programming speed of the pixel circuit is effectively increased.

A power supply provides power to a power terminal of an integrated circuit device under test (DUT). The DUT's demand for current at the power input terminal may temporarily increase due, for example, to state changes in the DUT. To limit variation (noise) in voltage at the power input terminal, a supplemental current is supplied to the power input terminal.

Provided is a massage roller or ball comprising: a) a rigid cylindrical or spherical body; b) a sheet of a heating pad placed over the cylindrical body; c) a rechargeable battery placed inside of the cylindrical or spherical body; wherein current from the battery makes the heating pad increase in temperature. Provided is a massage roller comprising: a) a rigid cylindrical body; b) two end caps, with each end cap placed at one end of the cylindrical body; c) a sheet of foam placed over the cylindrical body; d) a sheet of woven carbon fiber placed over the foam, the sheet of carbon having two conductors that do not touch each other; e) a cylindrical shell placed inside of the body; f) a rechargeable battery placed inside of the shell; g) two lead wires carrying current from the battery to the conductor, each wire connected to one of the conductors; wherein current from the battery heats the heating pad.

The invention discloses a pixel circuit of an active organic electroluminescence displayer and a driving method of the pixel circuit. The pixel circuit is arranged at the crossing part of a scanning line which provides the row form of control signals and a signal line which provides the column form of data signals. The pixel circuit comprises a first switch transistor, a second switch transistor, a third switch transistor, a fourth switch transistor, a driving transistor, an organic light-emitting diode, a first capacitor and a second capacitor. The pixel circuit can compensate the threshold voltage drift (including positive threshold voltage and negative threshold voltage) of the transistors, control signal multiplexing is carried out on several adjacent pixel rows, accordingly, the number of control signal lines is reduced, and the requirement for periphery driving is lowered. Therefore, cost is lowered, a high-speed programming mode can be achieved, and the active organic electroluminescence displayer is suitable for large-size and high-resolution displaying.

In a converter device, an N-type FET is connected in series between an input terminal and an output terminal and an N-type FET is connected between the side of the output terminal of the N-type FET, and a ground terminal. A smoothing circuit and a comparator circuit are connected to the side of the output terminal of the circuits. The output side of the comparator circuit is connected to an H/S driver circuit controlling the N-type FET₁ through an inverter and directly connected to an L/S driver circuit controlling the N-type FET₂. A reference voltage correction circuit is included in the comparator circuit, and the comparator circuit outputs an appropriate switching control signal by comparing a correction reference voltage, obtained through comparison of a divider voltage in accordance with the time average value of an output voltage with a reference voltage, with the divider voltage.