摘要:
The invention discloses a method for controlling the time sharing starting of electronic ballasts and a delayed-started electronic ballast. According to the method, the electronic ballasts are delayed-started after being energized, and delay time for the delayed starting of the electronic ballasts is a random number acquired based on the temperature of the ballasts. The delayed-started electronic ballast includes an electronic ballast body and a delay switch. After the adoption of the technical scheme of the invention, a delayer with the delay time set by virtue of random numbers corresponding to different environmental temperature is additionally arranged in the ballast, and multiple ballasts connected in parallel in a circuit can be started at different time points after different delay time under the control of the same control switch, which remarkably reduces current impact on a power grid and reduces a voltage drop condition.
摘要:
A ballast circuit for a lighting system using an induction fluorescent lamp utilizes an AC-DC rectification circuit, a DC-DC boost power conversion circuit, a DC-AC half bridge inverter circuit, and a resonating circuit to ignite the lamp and maintain substantially constant power output of the lamp, while the DC-AC half bridge inverter circuit is further comprised of a gate isolation transformer connected in a half bridge inverter schematic which uses a ballast integrated circuit (IC) to drive a high side MOSFET and a low side MOSFET and the gate isolation transformer electrically isolates a gate signal to the high side MOSFET.
摘要:
A light-emitting element driving circuit controls the luminance of light-emitting elements by using a PWM signal. A display device includes the driving circuit and multiple light-emitting elements. The driving circuit includes a control circuit that generates a control signal by using a divided signal based on an input PWM signal, and a light-emitting element driving unit that drive the light-emitting elements by using the control signal. The control signal includes a larger number of frequency components in comparison with frequency components of the input PWM signal.
摘要:
According to one or more embodiments, an inverter provides a light source with an input voltage. A protection circuit shuts down the inverter based on an overvoltage protection level that is detected based on the input voltage. A protection circuit control part shuts down the operation of the protection circuit during a predetermined interval. Abnormal operation of the protection circuit caused by a high voltage provided when the light source is turned on may be prevented. Therefore, a turn-on defect of the light source may be prevented.
摘要:
A low-power display control method and associated display controller is provided. The low-power display control method detects a sensing signal to generate a sensing result. A control signal is generated according to the sensing result to control a power conversion controller to operate in a low-power power saving mode. In response to a wake-up event, the control signal is deasserted and an associated auxiliary circuit is also turned off, and then the display controller is woken up to restore to a normal operating mode.
摘要:
A single stage electronic ballast with power factor correction is provided. The single stage electronic ballast can work under the present intensity discharge lamp without any change and provide higher efficient, lower power consumption of lighting system, and better lighting quality of lamps. The single stage electronic ballast can also provide a stable current to load (lamp) for a long time. The single stage electronic ballast includes a first switch and a second switch that are controlled with complementary switching so as to provide an output voltage in response to the input power source and the variation of the load.
摘要:
System and method for adjusting brightness of one or more cold-cathode fluorescent lamps. The system includes a voltage selector configured to receive a dimming voltage and a first threshold voltage and generate an output voltage. The output voltage is selected from a group consisting of the dimming voltage and the first threshold voltage. Additionally, the system includes an oscillator coupled to a first capacitor and configured to generate a ramp signal with the first capacitor, and a signal generator configured to receive the ramp signal and the output voltage and generate a first signal. The first signal corresponds to a lamp brightness level. Moreover, the system includes a brightness detector configured to receive the first signal and output a second signal. The second signal indicates whether the lamp brightness level is higher than a threshold brightness level.
摘要:
A dimming ballast allowing individual control of multiple lamps is described. The ballast includes a lamp driver to control at least one lamp. Further, the ballast includes a current sensing module , connected as part of a feedback loop from the at least one lamp to the lamp driver, the current sensing module being configured with a maximum allowable output current value for each lamp. A lamp resonant circuit, connected between the lamp driver and the at least one lamp, operates over the entire range of the output current values. A lamp status module is coupled to the lamp driver for monitoring at least one condition related to the at least one lamp being controlled. Moreover, a control module controls the lamp driver independently based on a feedback loop from the lamp status module. Various embodiments of the dimming ballast along with related methods are also described.
摘要:
A current control circuit for light emitting diodes includes a power source, a current converting unit, a switch control unit and a number of transformers. The current control circuit provides direct current. The current converting unit is electrically connected to the power source and includes two couples of field effect transistors. The switch control unit is electrically connected to the current converting unit and is capable of providing a number of pulse signals to control the current converting unit. The two couples of field effect transistors receive pulse signals from the switch control unit and are alternately switched on and off. The direct current from the power source is converted into corresponding alternating current for the transformers. The current control circuit can provide stable and consistent current, enabling light sources to keep uniform brightness.
摘要:
A circuit arrangement for striking a discharge lamp, comprising: a drive apparatus, having an output adapted to provide a drive signal with a predeterminable frequency; an inverter, which is coupled to the output of the drive apparatus, and having an output adapted to provide a square-wave signal with a predeterminable duty factor; a load circuit, which is coupled to the output of the inverter and has at least one terminal for the discharge lamp, the load circuit comprising a lamp inductor, which is coupled in series between the output of the inverter and the at least one terminal for the discharge lamp; a first control loop with a first reference variable, a first manipulated variable and a first controlled variable, the first control loop having a first time constant; a second control loop with a second reference variable, an auxiliary manipulated variable and a second controlled variable, the second control loop having a second time constant; and a strike detection apparatus, which is adapted to detect striking of the discharge lamp and, after detection of the striking to switch over the first and the second control loops from the striking operation mode to the continuous operation mode. The auxiliary manipulated variable of the second control loop represents the first reference variable of the first control loop, the first time constant being smaller than the second time constant by at least a factor of 10, and the first manipulated variable represents the duty factor of the output signal of the inverter.