45results about How to "High dimming accuracy" patented technology

The invention relates to a monolithic integrated LED (light emitting diode) backlight and LCD (liquid crystal display) power supply driving system. The driving system comprises a master control singlechip, two MOSFET (metal-oxide semiconductor field effect transistor) driving paths, two boost circuits composed of L1, D1, Q1, C1, R1, R2, R3, L2, D2, Q2, C2, R4, R5 and R6 as well as n controllable constant current sources, wherein n is a natural number. A PWM (pulse width modulation) signal output by one PWM module on the singlechip is amplified by virtue of the driving of an MOSFET, one boost circuit is driven to supply power to LEDs, about 110 LEDs are driven, and flexible expanding can be realized according to the actual requirement. The PWM (pulse width modulation) signal output by another PWM module on the singlechip is amplified by virtue of the driving of the other MOSFET, and the other boost circuit is driven to boost a 5V input power supply to 13V and supply power to an LCD, thus a power supply chip is saved and the cost is reduced. In the working period of the boost circuits, an AD (analog-digital) converter on the singlechip continuously detects the currents and voltages of the two boost circuits as well as the currents of all the LED channels, the working state of each module is monitored, and perfect protection function is provided for the system. A timer module on the singlechip provides PWM dimming support for the LED. Thus, the monolithic integrated LED backlight and LCD power supply driving system has higher cost performance.

The invention relates to a linear light modulation switching mechanism of a television measurement system of a large-caliber equipment. An optical filer support and an attenuation slice support of the mechanism are respectively fixed on platforms of two linear switching mechanisms. A first guide rail of the switching mechanism penetrates a platform by a through hole of the platform; a second guide rail is embedded into a groove; and two ends of the first guide rail and two ends of the second guide rail are respectively and fixedly connected with a first vertical plate and a second vertical plate. One end of a screw rod is movably connected with the first vertical plate and the other end of the screw rod passes through a through hole on the second vertical plate and is cooperated with the through hole. A motor is fixed on a third vertical plate of a pedestal and a rotating shaft penetrates the third vertical plate and is fixedly connected with the screw rod. And a nut is threadedly connected with the screw rod and is connected with the platform by a key; and a first spring and a second spring are sleevedly installed on the screw rod and are respectively at two sides of the nut. According to the invention, the provided mechanism has advantages of simple structure, accurate localization, high light modulation precision, low transmission noise, and dimensions of the appearance and the height are small; and moreover, air space between an optical filer and an attenuation slice is small.

The invention relates to a multi-channel LED dimming circuit, which comprises a dimming control unit, a feedback control unit, a voltage regulator and an LED channel array. Wherein the first output end of the dimming control unit is respectively connected with the first input end of the LED channel array and the first input end of the feedback control circuit, and the second output end of the dimming control circuit is connected with the second input end of the LED channel array; A first output terminal of the feedback control unit is connected to an input terminal of the voltage regulator; Anoutput terminal of the voltage regulator is connected with a third input terminal of the LED channel array; An output terminal of the LED channel array is connected to a second input terminal of thefeedback control unit. The invention can effectively suppress the overshoot current of the LED when the dimming MOS tube is turned on, so that the current flowing through the LED lamp string is more stable, the service life of the LED lamp is prolonged, and the flicker of the LED lamp is avoided.

The invention provides a PWM light modulation method and device. A plurality of PWM periods are combined into a control signal, so as to achieve the control of the brightness of illumination equipment. After the above design is employed, the light modulation precision cannot be affected while the frequency of a PWM signal is improve. Through the change of a combined scheme, more light modulation levels can be obtained, thereby achieving higher light modulation precision and a more smooth and flexible light modulation effect.

The invention discloses an LED dimming circuit, a dimming device and a dimming method for improving the dimming precision, wherein the LED dimming circuit for improving the dimming precision comprisesa voltage dividing module, a multi-path selection module, an adjusting module and a constant-current source module, wherein the voltage dividing module is used for dividing the reference voltage output by a direct-current voltage-stabilizing power supply, and outputting the corresponding voltage signals to the multi-path selection module through different taps; the multi-path selection module outputs a control signal to the adjusting module according to the received dimming data, and outputs the voltage signals output by the voltage dividing module corresponding to the taps to the constant-current source module; and the adjusting module is used for adjusting the values of the voltage signals output corresponding to the taps according to the control signal, and the constant-current sourcemodule controls the current flowing through an LED lamp string according to the current received voltage signal. By means of the design of the simple circuit structure, the LED dimming precision can be effectively improved, the circuit structure is simplified, and the implementation cost is lowered.

The invention provides an intelligent fine dimming dental chair oral lamp and a dimming method, and belongs to the field of lighting control. The dental chair oral lamp comprises a main adjusting module, a micro-adjusting module, a micro-controller module, a light source driving module, a lighting unit and a power source module, wherein the main adjusting module is connected with the micro-controller module, and is used for initial dimming of a lighting unit; the micro-adjusting module is connected with the micro-controller module, and is used for fine adjustment of the brightness of the lighting unit; the micro-controller module is used for receiving input signals of the main adjusting module and the micro-adjusting module and used for outputting a control signal to the light source driving module; the light source driving module is connected with the micro-controller module, and is used for receiving the control signal of the micro-controller module and used for brightness adjustment of the lighting unit; the lighting unit is connected with the light source driving module, and is used for receiving an adjusting signal input by the light source driving module and used for brightness updating; the power source module is connected with the main adjusting module, the micro-adjusting module, the micro-controller module and the light source driving module respectively, and is used for providing the power source. The dental chair oral lamp and the dimming method have the benefits that by rapidly combining initial dimming and fine dimming, dimming efficiency and dimming accuracy are improved, and the oral lamp is more convenient to operate.

The invention discloses a pulse width modulation (PMW) modulation circuit which specifically comprises a first transmission door, a first current comparer, a first alternative selector, a reset set (RS) trigger, two input nor gates, a phase inverter, a first N-channel metal oxide semiconductor (NMOS) tube, an error accumulation capacitor and a comparer with the selection function. The PMW modulator circuit can certainly modulate external input PWM signals according to current actually flowing through a light-emitting diode (LED), the duty ratio is adjusted, the duty ratio of the PWM signals actually participating in dimming in the circuit can be dynamically and correspondingly modulated as actual current change of the LED, and a signal driving switch of the LED is controlled to enable the luminance of the LED in all digital pulse periods to be equal to a preset value to improve PME dimming accuracy.

The invention relates to a dimming method suitable for load characteristic of an electroless fluorescent lamp. Pulse frequency modulation (PFM) is combined with pulse density modulation (PDM); based on satisfying different dimming outputs, the PFM dimming frequency at each PDM section is close to resonant frequency so as to realize the smooth dimming and guarantee the stable and reliable work of the electroless lamp. The control method overcomes the disadvantages of narrow dimming range of the PFM and step dimming of the PDM and realizes the smooth and wide electroless fluorescent lamp dimming. The electroless fluorescent lamp dimming method has advantages of broad dimming range, high dimming precision, high reliability and so on.

The invention relates to a multi-channel LED dimming circuit, comprising: a dimming control unit, a feedback control unit, a voltage regulator and an LED channel array; wherein, the first output terminals of the dimming control unit are respectively connected to the first input of the LED channel array terminal and the first input terminal of the feedback control circuit, the second output terminal of the dimming control circuit is connected to the second input terminal of the LED channel array; the first output terminal of the feedback control unit is connected to the input terminal of the voltage regulator; the voltage regulator’s The output end is connected to the third input end of the LED channel array; the output end of the LED channel array is connected to the second input end of the feedback control unit. The invention can effectively suppress the overshoot current of the LED when the dimming MOS tube is turned on, so that the current flowing through the LED lamp string is more stable, prolongs the service life of the LED lamp, and avoids the flickering of the LED lamp.

A controller for controlling dimming of a light-emitting diode (LED) light source provides a pulse signal by comparing a sensing signal indicative of a current flowing through the LED light source to a reference signal. The controller controls the current through the LED light source according to the pulse signal during a first state of a pulse-width modulation signal and cutting off the current through the LED light source during a second state of the pulse-width modulation signal. The controller receives a dimming request signal indicative of an operation of a power switch coupled between an AC power source and a bridge rectifier and adjusts both a level of the reference signal and a duty cycle of the pulse-width modulation signal based on the dimming request signal.

The invention discloses a dimmable LED (Light-emitting Diode) illumination drive circuit based on a silicon-controlled dimmer. The drive circuit comprises the silicon-controlled dimmer and a rectifier bridge, wherein the silicon-controlled dimmer and the rectifier bridge are sequentially connected with an input signal; an output of the rectifier bridge is connected with a silicon-controlled phase detection module; an output of the silicon-controlled phase detection module is connected with input ends of a pulse generator and a LOG curve generator; an output end of the LOG curve generator is connected with an input end of a sample-and-hold module; an output end of the pulse generator is connected with a control end of the sample-and-hold module; an output end of the sample-and-hold module is connected with an input end of a voltage controlled current source; and an output of the voltage controlled current source is connected with an LED load, and controls the current on the LED load. The drive circuit is high in dimming linearity, suitable for the human eye feeling, and high in dimming precision without delay, and can eliminate a wave on a control signal of the voltage controlled current source.

The invention relates to a light dimming method suitable for an electromagnetic induction lamp. By means of the method, subsection dimming, pulse number modulation (PDM) and frequency conversion are combined, and the novel subsection frequency conversion PDM light dimming method is obtained; N light dimming stages are set, different-integral-multiple electromagnetic induction lamp work cycles are set at the different light dimming stages to serve as PDM turn-on time, namely the PDM turn-on time set at the different light dimming stages is different. It is guaranteed that the PDM turn-on time at the same light dimming stage keeps unchanged, and smooth changes of the PDM light dimming empty rate are achieved by controlling the PDM turn-on time of the light dimming stages. By means of the light dimming method, the defect that the PDM light dimming scope is not wide is overcome, the shortcoming of PDM staged light dimming is overcome, and smooth and wide-scope light dimming of the electromagnetic induction lamp is achieved. The light dimming method has the advantages of being wide in light dimming scope, high in light dimming accuracy, high in reliability and the like.