4566 results about "Constant current source" patented technology

The invention comprises a system, catheter and method for measuring the cross-sectional areas and pressure gradients in any hollow organ, such as, for example, blood vessels. One embodiment of such a system includes: an impedance catheter capable of being introduced into a targeted site; a solution delivery source; a constant current source; a balloon inflation control device; and a data acquisition and processing system that receives conductance and / or pressure gradient data from the catheter and calculates the cross-sectional area of the targeted site. In one embodiment, the catheter has an inflatable balloon along its longitudinal axis, thereby enabling the breakup of any materials causing stenosis at the targeted site and / or distention and delivery of an optional stent into the targeted site.

A current direction detection circuit includes a monitoring transistor having a control terminal and an output terminal respectively connected with a control terminal and an output terminal of a ground side output transistor; an impedance element having one terminal connected with an input terminal of the monitoring transistor and the other terminal grounded; first and second constant-current sources; a diode-connected reference transistor interposed between the first constant-current source and ground potential; and a sensing transistor interposed between the second constant-current source and the impedance element and having a control terminal connected with the control terminal of the reference transistor. The current direction detection circuit is small yet capable of minimizing power loss of a switching regulator.

A cathode potential controller for controlling a common cathode potential applied to a self light emission type display panel in which an emission state of each of pixels is driven and controlled in accordance with an active matrix drive system, the cathode potential controller including: a self light emitting element; a constant current source; an electrode-to-electrode voltage measuring portion; a cathode potential determining portion; and a cathode potential applying portion.

The present invention is directed to a fluorescent light fixture assembly including a ballast and a novel lighting element that includes an array of LEDs and at least one converter module that enables the existing ballast providing an AC power input to supply DC power to the LED array. The lighting element includes a body that contains the LED array and the converter modules and shares the configuration of the lighting element that is to be retrofitted. The lighting element receives power from the pre-existing ballast, wherein the converter module provides a constant current source to power the LED array. Thus, the lighting element, including the converter module, replaces the conventional fluorescent light tube in a cost-effective retrofit manner with the existing ballast.

A novel and advantageous power supply is disclosed for lighting systems employing semiconductor light sources where the semiconductor light sources are connected in series. The power supply includes a constant current source to supply current to the semiconductor light sources and a bypass switch is provided around each semiconductor light source, or each sub-string of series connected semiconductor light sources. By opening or closing respective bypass switches, individual semiconductor light sources or sub-strings of semiconductor light sources can be illuminated or extinguished as desired. If the bypass switches are electrically controllable, such as semiconductor switches or relays, failures of one or more semiconductor light sources can be determined by the power supply and failed light sources can be bypassed and / or redundant semiconductor elements illuminated to replace failed light sources. Further, if the bypass switches are semiconductor switches, the power supply can employ pulse width modulation techniques to dim one or more semiconductor light sources as desired.

Disclosed are systems and methods which provide trial stimulators suited for use interoperatively and during patient trial. Trial stimulator embodiments provide a patient interface and / or clinician interface which appears and functions substantially the same as an interface of a pulse generator controller which will be used after a trial period. A compliance monitor feature may be provided to facilitate verifying the proper use of the trial stimulator during a trial period. A diagnostic feature may be provided to facilitate verifying proper operation of various aspects of a trial stimulator, such as electrode impedance analysis. Trial stimulators of embodiments provide stimulation to a plurality of tissues and / or areas of the body, such as spinal cord stimulation, deep brain stimulation, etcetera. Embodiments provide for multi-electrode stimulation and multi-stimulation programs. Embodiments are configured to provide active discharge of stimulation pulses as well as to utilize constant current sources in providing the stimulation pulses.

The invention discloses a battery managing system (BMS) testing platform comprising a testing platform main control computer, a high-precision cell voltage simulator, a high-precision large-current constant-current source, a high-precision thermotank, a battery managing system to be tested, a whole vehicle controller simulator and the like which are connected by CAN buses. The battery managing system is connected with a cell box air cooling device, a vehicle relay assembly and the like. The battery managing system testing platform can truly simulate the output state of a battery, comprising single cell voltage, total voltage, charging and discharging current, temperature and the like of the battery, can complete various communication and command functions, protection functions, battery heavy current applying process between the battery managing system and the whole vehicle, and the test and the verification on the functions of overhead protection and the like of the battery. The invention can carry out testing evaluation on the data collection precision of the battery managing system, the evaluation precision of the charge state of the battery and the like.

Electrical circuit componentry is switchable into a defibrillator circuit to deliver a constant pacing current to a patient. The circuitry may include a constant current source inserted in a leg of the defibrillator circuit or a resistor of selected value inserted between a high voltage source and the high side of a defibrillator circuit.

A dimmable, light-emitting diode (LED) power supply adapted to provide a direct current (DC), constant current (“constant current source”) from a conventional, phase-controlled 120 VAC, 60 Hz power source is disclosed. The constant current source of the present invention utilizes two processes to control dimming. In a first process, the phase angle of the input voltage is used to control the duty cycle of a line frequency pulse width modulation (PWM). In a second process, a proportional-current limit adjustment is used to control the average current to the LED during the ON time of the line frequency by PWM. As a result, at relatively low phase angles, peak currents can be lowered, reducing flicker and improving the audible noise levels generated by the circuit.

A method includes coupling electrodes to a patient's head and identifying whether any of the electrodes form a functional set, such that a desired therapeutic effect is achieved when the two or more electrodes deliver a total amount of current to the patient regardless of what portion of the total amount of current each respective electrode carries. One or more constant current sources are provided, each having a supply and return terminal, which supply and return equal amounts of current at any given time. The constant current source(s) are coupled to the electrodes in such a manner that each supply terminal and each return terminal is coupled to no more than the electrodes of a single one of the functional sets, if any, or to a single one of the electrodes not included in one of the functional sets.

High side driver circuitry for a defibrillator circuit employs respective capacitors connected to respective gates of silicon controlled rectifiers serving as high side switches. Applying a voltage pulse to a selected capacitor turns on the associated SCR. Positive turn-on of the high side SCRs is insured by inserting a constant current source into the low side activation current path at start-up.

The method and system described herein is designed to illuminate, control, and network LEDs lights used onboard marine platforms. Disclosed is a method and system for illuminating a portion of a marine vessel or platform. A lighting system is controlled by generating a lighting signal for controlling plurality of LED lights placed in a plurality of positions within the vessel. An LED space is designed to illuminate LEDs (or other lighting fixtures) by providing a controller for providing constant current source via a switching regulator configuration.

The present invention provides a current sensor capable of adjusting an offset value at a zero magnetic field more easily and detecting a current magnetic field generated by a current to be detected with high sensitivity and high precision. The current sensor has: first and second magnetoresistive elements disposed along a conductor so that resistance values change in directions opposite to each other in accordance with a current magnetic field generated by a current to be detected flowing in the conductor; and first and second constant current sources that supply constant currents equal to each other to the first and second magnetoresistive elements, respectively. The current sensor further includes a differential amplifier that detects the difference between voltage drops occurring in the first and second magnetoresistive elements by the constant current. The current to be detected is detected on the basis of the difference between the voltage drops.

In an EL display device which performs area grayscale display, image quality is improved and stabilized. A plurality of subpixels each having light emitting elements which emit light of approximately the same color and a plurality of monitor pixels each having the same number of subpixels as the pixel are provided. The light emitting element in the monitor pixel is manufactured at the same time as the light emitting element in the pixel, and the electrode of the light emitting element in the monitor pixel is connected to a different constant current source in each subpixel. A circuit for changing a potential of the electrode of the light emitting element in the pixel for each subpixel in accordance with a potential change of the electrode of the light emitting element of the monitor pixel, thereby the aforementioned purposes are achieved.

A system and method for providing a constant current source driver for a light emitting diode string. The converter includes a current sensor that derives feedback signal corresponding to a peak current through the light emitting diode string. The feedback signal is used by a controller to vary a duty cycle of the controller to regulate the average current. The controller is operable to regulate the average current as the number of light emitting diodes is increased and / or decreased.

A dimmable, light-emitting diode (LED) power supply adapted to provide a direct current (DC), constant current (“constant current source”) from a conventional, phase-controlled 120 VAC, 60 Hz power source is disclosed. The constant current source of the present invention utilizes two processes to control dimming. In a first process, the phase angle of the input voltage is used to control the duty cycle of a line frequency pulse width modulation (PWM). In a second process, a proportional-current limit adjustment is used to control the average current to the LED during the ON time of the line frequency by PWM. As a result, at relatively low phase angles, peak currents can be lowered, reducing flicker and improving the audible noise levels generated by the circuit.

A photoelectric converting apparatus of the present invention includes a photoelectric converting element, a resetting transistor in which a source is connected to the photoelectric converting element and a drain is connected to a resetting power source, a readout transistor in which a gate is connected to the photoelectric converting element and a drain is connected to a readout power source, a signal line connected to a source of the readout transistor, a selecting transistor connected between the readout power source or the signal line and the readout transistor, and a constant current source connected to the signal line.

A lighting apparatus includes a solid state lamp including one or more solid state lighting elements, and a power circuit including a current limiting device electrically connected to the lamp. The current limiting device configured to impose a maximum threshold on the current delivered to the lamp, wherein the current limiting device functions as essentially a constant current source. The lighting apparatus includes a housing for the power circuit and lamp, as a module unit.

A method and apparatus for driving LED's is disclosed, comprising the steps of receiving a desired intensity value, wherein the desired intensity value represents the desired intensity for the LED's; generating a first switching control signal, wherein the first switching control signal is a pulse width modulated signal whose duty cycle is based on the desired intensity value; switching the LED's on and off based on the first switching control signal, wherein the switching takes place when the desired intensity value is less than a first desired intensity value threshold; generating a desired constant current value based on the desired intensity value, wherein the desired constant current value represents the value of the desired constant current to drive the LED's; determining an actual constant current value, wherein the actual constant current value represents the value of the actual constant current driving the LED's; comparing the actual constant current value with the desired constant current value; and adjusting the output of the primary drive of the LED's so that the actual constant current value is equal to the desired constant current value. A system for providing LED backlighting of a display is also disclosed, comprising a first constant current source driver, wherein the constant current source driver comprises a primary drive and a step-up circuit; a first series connection of LED's, wherein the LED's are driven by the first constant current driver; and wherein the first constant current source provides a forward voltage of 42 volts or greater to drive the first series connection of LED's.

A drive circuit that compensates for the dispersion of the characteristics of drive transistors is disclosed. A switch SW2 is turned off, and switches SW1 and SW3 are turned on. Thereby, a constant current from a constant current source CC1 is flown in a drive transistor T1. Consequently, a gate voltage corresponding to the constant current Is written in the gate of the drive transistor T1. Then, the switches SW1 and SW3 are turned off, and the switch SW2 is turned on. Simultaneously, the voltage of a capacitor C1 on the side of the switch SW4 is varied according to a signal voltage, and thereby the voltage is added to the gate of the drive transistor T1 to flow a current corresponding to the signal voltage in the drive transistor T1.

A phase interpolator circuitry is composed of a delay line, and a phase blender circuit. The delay line delays a first input clock signal to develop a delayed clock signal. The phase blender circuit includes a first inverter receiving the delayed clock signal, and a second inverter receiving a second input clock signal phased away from the first input clock signal. The outputs of the first and second inverters are commonly coupled together. The phase interpolator circuitry additionally includes at least one of constant current sources: first one connected between a power terminal of the first inverter and a power supply, second one connected between a ground terminal of the first inverter and ground, third one connected between a power terminal of the second inverter and a power supply, and fourth one connected between a ground terminal of the second inverter and ground.

An RF amplifier comprises a power amplifier and a dual bias circuit. A dual bias circuit comprises a constant current source and a constant voltage source for biasing the power amplifier. The power may include a heterojunction bipolar transistor (HBT) or a bipolar junction transistor (BJT).

A converter system and method of operating a converter system are disclosed. The converter system comprises a converter power stage that can operate in a Discontinuous Conduction Mode (DCM) in a range of output currents and a Continuous Conduction Mode (CCM) in another range of output currents. The converter power stage includes at least an inductor with an inductor value and a control switch. The converter power stage provides an average current. A current controller is coupled to the converter power stage. When the converter power stage operates in DCM, the converter power stage provides the average current and the current controller is configured to measure the inductor value of the inductor. Furthermore, the current controller can also be configured to measure an input-to-output conversion ratio from the converter power stage.

The invention discloses a multichannel constant-current control circuit applicable to an LED driver, comprising a single output constant-current source and a plurality of channels of output circuits.The multichannel constant-current control circuit is characterized in that each output circuit comprises a current equalizing circuit, a current equalizing control circuit and a load consisting of a plurality of LED lamps; the input of each channel of current equalizing control circuit is from a sampling signal of the sampling resistor to output current, and becomes a public connecting wire afterbeing converted by the current equalizing circuit; the public connecting wire is connected with the other channels to form a current equalizing bus; each channel of current sampling signal and the current equalizing bus voltage are compared and adjusted in the current equalizing control circuit; and an output signal of the current equalizing control circuit can control the size of impedance of a liner adjusting tube of the corresponding current equalizing circuit, then control the size of each channel of current and realize current equalization. The multichannel constant-current control circuit has simple circuit structure and low cost, and is applicable to standard multichannel constant current control of the rear stage of a single-channel constant current power supply.

A method and apparatus for driving LED's is disclosed, comprising the steps of receiving a desired intensity value, wherein the desired intensity value represents the desired intensity for the LED's; generating a first switching control signal, wherein the first switching control signal is a pulse width modulated signal whose duty cycle is based on the desired intensity value; switching the LED's on and off based on the first switching control signal, wherein the switching takes place when the desired intensity value is less than a first desired intensity value threshold; generating a desired constant current value based on the desired intensity value, wherein the desired constant current value represents the value of the desired constant current to drive the LED's; determining an actual constant current value, wherein the actual constant current value represents the value of the actual constant current driving the LED's; comparing the actual constant current value with the desired constant current value; and adjusting the output of the primary drive of the LED's so that the actual constant current value is equal to the desired constant current value. A system for providing LED backlighting of a display is also disclosed, comprising a first constant current source driver, wherein the constant current source driver comprises a primary drive and a step-up circuit; a first series connection of LED's, wherein the LED's are driven by the first constant current driver; and wherein the first constant current source provides a forward voltage of 42 volts or greater to drive the first series connection of LED's.

A drive circuit that compensates for the dispersion of the characteristics of drive transistors is disclosed. A switch SW2 is turned off, and switches SW1 and SW3 are turned on. Thereby, a constant current from a constant current source CC1 is flown in a drive transistor T1. Consequently, a gate voltage corresponding to the constant current Is written in the gate of the drive transistor T1. Then, the switches SW1 and SW3 are turned off, and the switch SW2 is turned on. Simultaneously, the voltage of a capacitor C1 on the side of the switch SW4 is varied according to a signal voltage, and thereby the voltage is added to the gate of the drive transistor T1 to flow a current corresponding to the signal voltage in the drive transistor T1.

An LED array switching apparatus comprises, on a single PCB substrate: a plurality of LED arrays D1 to Dn connected in series, each LED array having a forward voltage; an AC voltage supply coupled to the plurality of LED arrays; and a plurality of constant current sources G1 to Gn, coupled to outputs of LED arrays D1 to Dn, respectively, each of the constant current sources being switchable between a current regulating state and an open state such that as the voltage of the AC voltage supply increases, LED arrays are switched on and lit to form a higher forward voltage LED string, and as the voltage of the AC voltage supply decreases, LED arrays are switched off and removed from the LED string starting with the most recently lit LED array.

The present invention is an apparatus to enhance the Life of LED devices in an LED matrix for illumination. It comprises of a spare LED matrix in addition to a main LED matrix. It further comprises of a constant current source which is the power source. Such constant current source is coupled directly to said main LED matrix and powers it up accordingly. In adverse conditions, say when the ambient temperature is high, continuous operation of said main LED matrix at full power will deteriorate the LED life. A power converter coupled to said constant current source operates and draws current to power on said spare LED matrix. This relieves said main LED matrix from full power and the reduction in illumination is largely compensated by said spare LED matrix. This invention further comprises a controller which senses temperature and other parameters and operates said spare LED matrix intelligently. The present invention is also a method to operate said apparatus to maximize LED life or to maximize illumination.

Detecting the rotational direction of a rotor is feasible by allowing a constant current source to supply a constant current flowing from an electric potential supply line to the earth in response to a turning-on action of a switch. Accordingly, detecting both the rotational speed and the rotational direction of the rotor is feasible by using three wiring cables of a power source line, an earth line, and a signal line outputting a pulse signal in accordance with the rotation of the gear. Using such a one-stage voltage adjustment enables the detection signal processing circuit to reduce electric power consumption compared with a system requiring a two-stage voltage adjustment.

The invention relates to a constant current output type induction type wireless power transmission converter and a parameter selection method of the constant current output type induction type wireless power transmission converter. The constant current output type induction type wireless power transmission converter and the parameter selection method are suitable for induction type wireless power transmission occasions with fixed air gaps and current type loads. The converter comprises a high-frequency inverter circuit, a primary side compensation capacitor, a loose coupling transformer, an auxiliary side compensation capacitor, a rectification filtering circuit and a load. The resonant frequency of the primary side compensation circuit is equal to that of the auxiliary side compensation circuit, the high-frequency inverter circuit works at the resonant frequency, converter output currents are from a constant current source, the magnitude of the output currents is only relevant to input voltages and the mutual inductance of the loose coupling transformer, input impedance is pure, reactive circulation and device stress are reduced, and efficiency is improved. Converter constant current output characteristics are taken into consideration in the parameter selection method, and on the premise that the distance between the air holes, the size of the transformer and the load are given, mutual inductance, inductance values and coupling coefficients of primary side windings and auxiliary side windings are acquired iteratively with efficiency maximization of the converter as the goal.