44results about How to "Avoid strobe" patented technology

An LED driving device and its method are suitable for driving and regulating an illumination brightness of at least one LED. After switching the phase angle of an alternating voltage through a regulation circuit, an integration circuit and a filter circuit are utilized to generate a stable constant voltage. Next, the magnitude of the constant voltage is regulated in stage through a driving circuit based upon a control signal of a control circuit, and the voltage is converted into a constant current for driving the LED. Accordingly, the invention utilizes the constant current with stage variation to achieve the effect of linear dimming to prevent flickering.

The invention provides an adjustable illuminating lamp capable of imitating natural lights, comprising a light-emitting light source, a driving power supply, a control device and a time signal generator, wherein the driving power supply is electrically connected with the light-emitting light source; the control device is used for controlling the driving power supply; the time signal generator is connected with the control device in a signal manner; the light-emitting light source at least comprises a first secondary light source and a second secondary light source; a C / P (Citopic) value of emitted lights of the first secondary light source is more than 3.0 and the C / P value of the emitted lights of the second secondary light source is less than 2.5; the C / P values which are changed along with time and light strength information are stored in the control device; time information is sent to the control device by the time signal generator and a control signal is output to the driving power supply by the control device according to the input time information; the driving power supply is used for respectively controlling the strength of all the secondary light sources, so that a light source with the corresponding C / P value and light strength is formed by the light-emitting light source. The adjustable illuminating lamp capable of imitating the natural lights, provided by the invention, has the substantial characteristics of being beneficial to human health and being particularly applicable to habitation environments including indoor offices, homes and the like, and closed environments including airplanes, submarines for illumination and the like.

Disclosed are light-emitting diode (LED) driver circuits, methods, and a switch mode power supply. In one embodiment, an LED driver can include: (i) a silicon-controlled rectifier (SCR) and a rectifier bridge configured to receive an AC voltage, and to generate a phase-loss half sine wave voltage signal; (ii) a threshold voltage control circuit configured to receive a threshold voltage and an input voltage signal that represents the phase-loss half sine wave voltage signal, and to determine whether to output the threshold voltage based on angle information of the input voltage signal; (iii) a first control circuit configured to compare the input voltage signal against the threshold voltage output by the threshold voltage control circuit, and to generate a first control signal; and (iv) a power switch controllable by the first control signal to be off until an absolute value of the AC voltage is reduced to zero.

Disclosed is a light source device applied to collecting images of spherical objects which easily generate specular reflection such as on pearl and the like. The existing light source only can emit uniform light to one surface of a spherical object, but can not resolve problems of shadow, facula, specular reflection and the like caused by uneven illumination on the surface of the object. The light source device comprises a sphere, which is characterized in that the sphere comprises an outer sphere and a transparent inner sphere, the outer sphere and the inner sphere have the same sphere center, same camera shooting holes are arranged on the inner sphere and the outer sphere, the camera shooting hole on the inner sphere is communicated with the camera shooting hole on the outer sphere, the outer sphere is equipped with a plurality of luminous bodies which emit light inwards, and the upper end and the lower end of the sphere is equipped with through holes. The light source device resolves problems that in the image collecting process, the surface of the pearl generates shadow, facula, specular reflection and the like caused by uneven lighting.

The invention relates to an electronic ballast and its working method. It has a half-bridge electronic ballast for driving fluorescent lamps or HID lamps to emit light; It also has: a central control circuit connected to the inverter frequency control terminal of the half-bridge electronic ballast; a voltage sampling circuit connected to the voltage detection signal input terminal of the central control circuit; transformer rectification and stabilization The voltage circuit is connected with the city AC and is used to provide power to the central control circuit and the voltage sampling circuit; the voltage sampling circuit is used to detect the voltage fluctuation of the city AC through the transformer rectification and voltage stabilization circuit; Fluctuation controls the inverter frequency of the half-bridge electronic ballast to keep the luminance of fluorescent lamps or HID lamps constant. The electronic ballast of the invention can improve the light efficiency of the fluorescent lamp or the HID lamp, prevent flickering and keep the brightness constant.

The invention discloses a light-emitting diode lighting system and a control method driven by alternating current without flickering. The light-emitting diode lighting system has a rectifier, a string of light-emitting diodes, a mobile power supply and a controller. The rectifier receives an AC input voltage to generate a rectified voltage on the input power line and a ground voltage on the ground line. The LED string includes a plurality of LEDs connected in series and has a main anode and a main cathode. The main anode is coupled to the input power line. The mobile power supply is connected to the input power line and the main cathode. The controller guides the first driving current from the main cathode to the ground wire, and guides the second driving current from the mobile power supply to the ground wire. The second driving current increases the stored electric energy of the mobile power supply. Both the first and second driving currents flow through the LED strings. When the AC input voltage is about zero volts, the mobile power supply releases electric energy to make at least one LED emit light.

Embodiments of the invention provided a driving circuit for powering a light-emitting diode (LED) light source. The driving circuit includes a rectifier, a filter capacitor, and a control circuit. The rectifier converts an AC voltage from an AC power source to a rectified AC voltage. The filter capacitor coupled to the rectifier filters the rectified AC voltage to provide a DC voltage. The control circuit controls power supplied to the LED light source. The control circuit enables a discharging current periodically to discharge the filter capacitor if a switch coupled between an AC power source and a rectifier is turned off and disables the discharging current if the control circuit determines that the switch is turned on.

The invention discloses a high-power factor and non-strobe LED drive circuit which comprises a voltage reduction type converter structure and a boosting type converter structure at the same time. By the adoption of the structure, the high-power factor and non-strobe LED drive circuit can continuously work within one power frequency cycle, energy is transmitted from input voltage to output voltage all the time, and output current does not have power frequency ripple waves. According to the high-power factor and non-strobe LED drive circuit, the purposes of improving the power factor and avoiding strobe can be achieved at the same time without a large output capacitor or a special power factor correction constant output control chip.