3447 results about "Square wave" patented technology

The present invention provides for systems and methods for dimming a LED matrix functioning as a backlight to an avionics display. A system according to an embodiment of the present invention comprises a processor for receiving inputs of ambient lighting and temperature, as well as light generated by the LED matrix. The processor provides modulated pulse wave signals (square waves) to two control circuits for controlling the LED matrix in two modes. At low dimming levels, the processor modulates the duty cycle of a first square wave for affecting the light level and maintains a minimal duty cycle of a second square wave. Once the highest light level is obtained by increasing the duty cycle of the first square wave, the processor then modulates a second square wave by increasing its duty cycle. The duty cycle of the second square wave is modified by a circuit to produce a voltage level which is provided as an input to control light level of the LED matrix. As the duty cycle of the second signal is increased, so is the voltage level provided to the LED matrix and the light generated by the LED matrix.

A square wave generator suitable for use with an electrosurgical device is provided. The square wave generator includes a voltage source configured to output a waveform and a comparator operatively coupled to the voltage source and configured to output energy in the form of a square wave. The generator may also include at least one sensor configured to sense an operational parameter of the energy outputted from the comparator and to provide a sensor signal corresponding thereto and a controller adapted to receive the at least one sensor signal and in response thereto control the voltage source.

A ground fault detector and detection method for a vehicle that can determine the cause of the occurrence of a ground fault after detecting the presence of the ground fault. The output terminal of a high-voltage battery is connected to one side of a coupling capacitor. In operation, a pulse signal is applied to a measurement point on the other side of the coupling capacitor, and the voltage generated at that point is detected. Whether the high-voltage battery or the electrical equipment units are grounded is determined. To determine the cause of the ground fault, the oscillation frequency of the square-wave pulse signal is changed and applied to the measurement point. From the change in voltage amplitude detected, it is determined whether the cause of the ground fault is a resistive or a capacitive ground fault, according to the change in the impedance of the battery or the units.

The present invention discloses a backlight including external electrode fluorescent lamps and a method for driving the backlight. The backlight includes fluorescent lamps having external electrodes made of an electrically conductive material for wrapping the outer peripheral surfaces including edge cross-sections on both ends of a glass tube with a layer of fluorescent substance applied thereon. The backlight is constructed in a manner that a plurality of such fluorescent lamps are installed at the outer portions of a plastic light guide, and an alternating current type power source is applied from the outside to the fluorescent lamps by installing a plurality of the fluorescent lamps between a reflecting plate and a diffusing plate and electrically connecting them with one another. The backlight of the present invention is driven by a square wave from a switching inverter, and is characterized by the use of an overshooting waveform and a self-discharge effect favorable to an initial discharge, thereby driving it using a low frequency of several dozen kHz and thus realizing high luminance and high efficiency.

A multi-output switching power supply may include a PWM regulator circuit arranged in cascade upstream of each output to receive, as an input, a square wave voltage signal with a predetermined duty cycle. The regulator circuit may include an auxiliary switching device for modulating the duty cycle of the input signal to supply, as an output, a regulated direct current voltage. A control circuit for the PWM regulator circuit may include a detector circuit for detecting the trailing edges of the voltage signal input to the regulator circuit which emits a pulse coinciding with each of the trailing edges. The control circuit may also include a ramp signal generator that is controlled by the emitted pulses. The ramp signal generator may be connected to the non-inverting input of a comparator having an inverting input for receiving a signal indicative of the error in the regulator output voltage.

A single-stage electronic ballast device outputs a square wave current to drive an HID lamp, which includes a rectifying and power factor correction unit, a bridge converter and a controller circuit. The rectifying and power factor correction unit has an input connected to an AC power source to rectify an AC power to a DC power. The bridge converter comprises two bridge arms formed by four switches, load terminals defined by midpoints of the two bridge arms and the HID lamp is connected between the load terminals. The bridge converter converts DC current to square wave current to drive the HID lamp with power control. The load terminals are selectively connected to output of the rectifying and power factor correction unit to adjust waveform of input current for higher power factor. The controller circuit has output connected to DC link voltage terminal and load terminal of the bridge converter.

A resonant DC-DC converter used to drive an LED array includes a half-bridge converter configured to receive DC input power and produce a square wave voltage. A resonant tank circuit that includes an inductive element, a first resonance capacitor, and a second resonance capacitor, is coupled to the half-bridge converter to receive the square wave voltage such that a generally sinusoidal AC voltage is produced across the second resonance capacitor. An output transformer with a primary winding and one or more secondary windings, is coupled in parallel to the second resonance capacitor, and a clipping circuit is coupled to the primary winding such that the voltage across the primary winding does not substantially exceed the voltage of the DC input power. An output rectifier is coupled to the one or more secondary windings of the output transformer and is configured to produce a generally DC output voltage.

A mixer circuit of the present invention includes a gain stage configured to receive a first signal and a modulated bias current, and in accordance therewith, produce an output signal, the gain stage generating a first current and receiving the modulated bias current from a bias circuit on a common node. The bias circuit includes an input configured to receive a second signal, and in accordance therewith, generate the modulated bias current. The mixer circuit also includes a current shunt circuit for generating a second current. The first current, the second current, and the modulated bias current are coupled to the common node. In one embodiment, the first signal is approximately a square wave, and the frequency of the first signal is one-third the frequency of the second signal.

A method for the detection and the characterization of corrosion in multi-layer metallic structures using a pulsed eddy current technique. For this technique, a coil (or coils) is used both as field source (driven by a square wave voltage-controlled excitation), and/or as field sensor (measuring a transient response). The field sensor allows the capture of information about the condition of the area of the structure under inspection. The ability of this technique to detect corrosion hinges on the use of a transient response feature (i.e., Lift-off Point of Intersection) to infer the presence of material loss. With the help of a calibration standard, the Lift-off Point of Intersection provides the ability to quantify material loss in multi-layered structures. The results obtained with this method are independent of lift-off variations inherent to field inspections (i.e., changes in distance between the transducer and test object).

The invention relates to a square wave three phase brushless permanent magnet dc motor. In order to solve the problems existed in the prior square wave permanent magnet motor and sine wave permanent magnet motor, a magnetic pole number 2P is equal to 8 on a rotor iron core; a slot number Z is equal to 12 of a stator iron core, twelve teeth comprises three big teeth, three middle teeth and six small teeth;a mechanical angle ratio of the big teeth is 50 degree +/- 5 degree, the mechanical angle ratio of the middle teeth is 40 degree +/- 5 degree,the mechanical angle ratio of the small teeth is 15 degree +/- 5 degree,and a total mechanical angle ratio of one big tooth plus one middle tooth plus two small teeth is equal to 120 degree.The three phase concentrated windings respectively wind on the big teeth and middle teeth, each phase only has two concentrated windings and the three phase motor only has six concentrated windings. The motor can generate a stable torque when driven by a three phase square wave current and a torque fluctuation index is equivalent to that of the sine wave permanent magnet. The motor of the invention has a series of advantages of minimum winding end, minimum air gap, minimum material, minimum locating torque and minimum loss or the like.

The invention discloses a DC/DC converter. The DC/DC converter includes a square wave generator, which is used to output a series of voltage in form of square wave. The said square wave generator includes a serial capacitor which is connected to serial inductor and parallel inductor. Primary side of transformer is cascaded to a serial inductor in the DC/DC converter, then connected to an inductorin parallel. Secondary side of transformer is connected to a rectification circuit so as to provide a rectified DC voltage for output load circuit. The first characteristic resonance frequency of theserial capacitor and the serial inductor are expressed as fs. The second characteristic resonance frequency of the serial capacitor and the serial inductor as well as parallel inductor are expressed as fn where fs>fn. Switching of variable frequency in the converter carries out the output adjustment. Based on frequency switching between first and second characteristic resonance frequency, the converter realizes high conversion efficiency when working under high input voltage.

A system for producing an image using an imaging system includes a) transmitting at least one signal of energy toward an object to be imaged by using two transmitters having the same output amplitude but of an opposite sign, or by using one transmitter to perform the task; b) exciting at least one transducer element to produce limited-diffraction array beams or their square-wave approximations with two levels of quantitations for both sine and cosine functions, c) weighting the received signals spatially with limited-diffraction array beams, their square-wave approximations, or spatial Fourier transform, and d) digitizing and then transferring received signals through high-speed optical fibers to a system for image reconstructions.

A radio comprising an FET mixing device for multiplying a first-frequency signal with a second frequency signal to generate a third frequency analog mixer output signal. A local oscillator input port receives a periodic sinusoidal local oscillator signal at a local oscillator frequency from an external local oscillator source. A drive circuit generates a substantially square-wave two-voltage level switching signal for driving said mixing device. An analog-to-digital converter generates a digital representation of said third frequency analog mixer output signal.

The invention provides a dimmable LED (Light-Emitting Diode) driving circuit and a driving method. An input current in a first power-level circuit is controlled as a square wave signal within a rectifier conducting time interval by an input current control circuit, the peak value of the input current is a constant value and meets the requirement of the minimum load current of an electronic transformer, and the valley value of the input current is zero; and the input current is kept at zero within a rectifier nonconducting time interval. The load current of the electronic transformer can be kept larger than the minimum load current, and thus, a normal working state can be kept in the working process, and the problem of LED load flicker caused by the switching off of the electronic transformer is avoided; in addition, information on the input current is detected through a dimmable signal generating circuit so that a dimmable signal for representing information on a conduction angle of a rectifier is obtained, an LED load is precisely dimmed, the dimming range is wide, and the dimming effect is good; and finally, constant-current control for the current of the LED load is realized by an output current control circuit, and therefore, the brightness stability of the LED load is ensured.