CN2798490Y

CN2798490Y - LED desk lamp

Info

Publication number: CN2798490Y
Application number: CN 200520059296
Authority: CN
Inventors: 谭浩垣
Original assignee: Individual
Current assignee: Individual
Priority date: 2005-06-07
Filing date: 2005-06-07
Publication date: 2006-07-19
Anticipated expiration: 2015-06-07

Abstract

The utility model discloses an LED reading lamp, which comprises an EMI filter, a rectifying and filtering circuit, a switching power supply circuit and an LED light source. The utility model is characterized in that the switching power supply circuit comprises a high-frequency transformer T1, a power supply management integrated circuit U2, a feedback circuit, a voltage stabilizing circuit, and a low-frequency rectifying and filtering circuit, wherein the same name end of a primary winding of the high-frequency transformer T1 is connected with an output foot of the U2, and the same name end of a secondary winding of the T1 is connected with the low-frequency rectifying and filtering circuit. The output end of the low-frequency rectifying and filtering circuit is connected with the feedback circuit and the voltage stabilizing circuit. Actual voltage at the output end of the low-frequency rectifying and filtering circuit is compared with reference voltage generated by the voltage stabilizing circuit by the feedback circuit, and the feed back circuit sends information back to the U2. Using the structure, the utility model makes stabile work under voltage between 85V and 265V, isolates between high voltage and low voltage, does not generate frequent flicker, reduces impact for the light source, has the advantages of good light regulation, stable brightness and dose not influence by the fluctuation of urban power supply.

Description

The LED desk lamp

Technical field

The utility model relates to a kind of LED desk lamp.

Background technology

Semiconductor LED light source caloric value is few, does not have radiation, and the efficiency conversion rate is very high, belongs to typical green illumination light source, and the trend that replaces conventional incandescent and fluorescent lighting is arranged.Yet the primary stage that also is in research and development and test manufacture of semiconductor lighting, there are many defectives on the technical merit product quality.

LED desk lamp on the market adopts " resistance-capacitance depressurization " and " Industrial Frequency Transformer " power supply more, wherein " resistance-capacitance depressurization " circuit is simple, directly powers with the 220V civil power, and city's electro-mechanical wave is bigger, very easily light and shade changes with city's electro-mechanical wave in the brightness of light fixture, and this has just lost the advantage that led light source does not have stroboscopic.Add that " resistance-capacitance depressurization " circuit and civil power do not have isolation, the electric leakage accident takes place easily, and when being switched on or switched off power circuit, capacitor charge and discharge moment is attended by impulse current, the major injury led chip, even may cause semiconductor PN to puncture, cause LED to lose efficacy.And use the LED lamp of Industrial Frequency Transformer power supply, owing to there is not the voltage stabilizing measure, the operating current of the LED electric current that oversteps the extreme limit easily when line voltage is high very easily damages led chip, and is bright inadequately again when voltage is low.

Summary of the invention

For overcoming the above-mentioned defective of prior art, the purpose of this utility model is to provide a kind of has the good LED desk lamp of good protection, brightness stability and dimming behavior to led light source.

In order to solve above technical problem, technical solution adopted in the utility model is: electromagnetic interface filter, current rectifying and wave filtering circuit are arranged in the LED desk lamp, after the interference signal of the external AC power supplies of filtering AC power supplies become level and smooth direct current, current rectifying and wave filtering circuit is connected with switching power circuit, and this switching power circuit is connected the led light source of one group of series connection again by interface.Comprise high frequency transformer T1, power management integrated circuit U2, feedback circuit, voltage stabilizing circuit, low frequency current rectifying and wave filtering circuit in the above-mentioned switching power circuit, wherein 5,6,7,8 pin of the end of the same name of the elementary winding of high frequency transformer T1 and U2 join, the end of the same name of the secondary winding of T1 connects the low frequency current rectifying and wave filtering circuit, the output of low frequency current rectifying and wave filtering circuit connects feedback circuit, voltage stabilizing circuit, and the output of feedback circuit connects the feedback pin of power management integrated circuit U2.Feedback circuit is compared the virtual voltage of the output of low frequency current rectifying and wave filtering circuit with the reference voltage that voltage stabilizing circuit produces, feed back to U2.Voltage stabilizing circuit also connects a brightness regulating circuit.

Adopt structure of the present utility model, can be under 85V-265V voltage steady operation, the LED operating voltage is a dc low-voltage, and is isolated between the high-low pressure, do not produce stroboscopic, and reduces the impact to light source, helps to prolong the useful life of LED.Have dimming function, and good stable is arranged, be not subjected to the influence of city's electro-mechanical wave.

Description of drawings

Fig. 1 is a functional-block diagram of the present utility model;

Fig. 2 is the circuit structure diagram of the utility model one embodiment.

Embodiment

Introduce the utility model in detail below in conjunction with accompanying drawing.

Referring to Fig. 1, Fig. 2.

Electromagnetic interface filter one end of LED desk lamp is by the external AC power supplies of input protection circuit, the other end is through rectifier bridge BD1, the current rectifying and wave filtering circuit that capacitor C 1 is formed connects switching power circuit, comprise high frequency transformer T1 in the above-mentioned switching power circuit, power management integrated circuit U2, feedback circuit, voltage stabilizing circuit, the low frequency current rectifying and wave filtering circuit, wherein the elementary winding of high frequency transformer T1 of the same name terminates on the output pin of U2, the end of the same name of the secondary winding of T1 connects the low frequency current rectifying and wave filtering circuit, the output of low frequency current rectifying and wave filtering circuit connects feedback circuit, voltage stabilizing circuit, feedback circuit is made up of photoelectrical coupler U1 and resistance, and wherein the output of U1 connects the feedback pin of power management integrated circuit U2; The K utmost point of voltage-stabiliser tube U3 connects the reflection end negative pole of U1 in the voltage stabilizing circuit, and U1 compares the virtual voltage of the output of low frequency current rectifying and wave filtering circuit with the reference voltage that U3 produces, feed back to U2.

This switching power circuit is connected one group of led light source through the socket type connector.

In Fig. 2, piezo-resistance R1, insurance F1 form input protection circuit, and the protection of overvoltage, overcurrent is provided for power input.Common mode inductance L1, safety capacitor C 2, C9 form electromagnetic interface filter, stop the interference feedback that circuit produces in the lamp to arrive electrical network, also can stop the interference of electrical network to enter in the desk lamp.

Power management integrated circuit U2 adopts the VIPER22A type, inner integrated overvoltage, overcurrent, overheating protection circuit.

The low frequency current rectifying and wave filtering circuit is made up of rectifier diode D1, filter capacitor C7, and D1 exports low-voltage DC with low pressure high-frequency ac electric rectification, the C7 filtering high frequency composition wherein of big electric capacity.

Voltage stabilizing circuit is made up of voltage-stabiliser tube U3, resistance R 4, R5, R6, capacitor C 6, and U3 produces a precise voltage, contrasts with the power supply virtual voltage in U1.Feedback circuit comprises photoelectrical coupler U1 and resistance R 3, and U1 is with the error of output voltage, and the feedback end that changes into signal of telecommunication input U2 again is the 3rd pin.

Brightness regulating circuit is formed by regulating resistance R 9, resistance R 7 and capacitor C 8.By adjusting the resistance of R9, regulate the burning voltage of U3, thereby regulate output voltage to reach the purpose of light modulation.

Be connected on the interchange input pin of rectifier bridge BD1 from the power frequency electricity of L1 output.The BD1 output plus terminal connects filter capacitor C1 positive pole, and negative terminal connects the C1 negative pole.The different name termination C1 positive pole of the elementary winding of T1,5,6,7,8 pin of termination U2 of the same name.R2, C3 parallel connection, one terminates at the C1 positive pole, and the other end is connected with D3 again, and the D3 positive pole is connected on the end of the same name of the elementary winding of T1.The feedback stage winding of T1, termination high pressure of the same name ground, different name termination D2 positive pole.The D2 negative pole connects U2 the 4th pin, U1 receiving terminal collector electrode and C4 positive pole.The termination high pressure ground of 1 pin of U2,2 pin, C4 negative pole, C5.Another pin of C5 is connected with 3 pin of U1 receiving terminal emitter, U2.

The positive pole of T1 secondary winding termination D1 of the same name.The D1 negative pole meets C7 positive pole, R3 and R5.The positive pole of another termination of R3 U1 transmitting terminal.The negative pole of U1 transmitting terminal connects the K utmost point of U3.The R4 two ends are connected two interpolars of U1 transmitting terminal.C6 is connected the R utmost point and the K interpolar of U3.The R utmost point and the R6 of another termination of R5 U3.R6 meets R7, C8 positive pole and R9.The A termination low pressure ground of T1 secondary winding different name end and C7 negative pole, C8 negative pole, R7, R9, U3.C9 two terminates between high pressure ground and the low pressure ground.

The positive pole of light-emitting diode D4, D5, D6, D7, D8, D9 is connected mutually with negative pole.The C7 positive pole connects the D4 positive pole.The D7 negative pole connects R8 one end, another termination of R8 C7 negative pole.

Energized; electric current is through insurance F1 overcurrent protection; switch S 1 is added in piezo-resistance R1 two ends, and piezo-resistance provides overvoltage protection; electromagnetic interface filter filtering through L1, C2 composition; alternating current becomes high voltage direct current through BD1 rectification, C1 filtering, through the elementary winding of T1, is added in 5,6,7,8 pin of U2; the U2 work that is triggered, the electric current of feedback winding is filtered into the U2 power supply through D2 rectification C4.The secondary winding electric current becomes low-voltage DC through D1, C7 rectifying and wave-filtering simultaneously, uses for light source.R3 is to the direct voltage current limliting of output, and for the U1 sampling, R4 is used for adjusting the operating current of U3.Resistance R 5, R6 and U3 form a reference voltage, and it forms feedback circuit with U1, and voltage error is fed back to 3 pin of U2, and U2 adjusts operating state according to this error voltage, makes the voltage at C7 two ends and light-source brightness keep stablizing.C5 is used for the high frequency composition in the filtering DC feedback voltage.R2, C3, D3 form the drain electrode protective circuit, prevent that the peak voltage that T1 produces from damaging U2.Be connected on after R9, the R7 parallel connection between R6 and the low pressure ground, adjust the voltage that reference voltage that R9 just can adjust U3 just can be adjusted output C7.C8 is connected in parallel on R7, the R9, makes the transition of light source light and shade more level and smooth during adjusting R9.C9 is connected on the interference that can reduce power supply between high pressure ground and the low pressure ground.D4-D9 is six high brightness LEDs of forward series connection, R8 as the current-limiting resistance string therein, the restriction electric current is excessive and damage LED.High brightness white light-emitting diode D4-D9 and current-limiting resistance R8 are connected into one group, and a led light source can constitute by above-mentioned some groups.

Claims

1, the LED desk lamp, comprise electromagnetic interface filter, current rectifying and wave filtering circuit, switching power circuit and led light source, it is characterized in that: comprise high frequency transformer T1 in the described switching power circuit, power management integrated circuit U2, feedback circuit, voltage stabilizing circuit, the low frequency current rectifying and wave filtering circuit, wherein the end of the same name of the elementary winding of high frequency transformer T1 and the output pin of U2 join, the end of the same name of the secondary winding of T1 connects the low frequency current rectifying and wave filtering circuit, the output of low frequency current rectifying and wave filtering circuit connects feedback circuit, voltage stabilizing circuit, the output of feedback circuit connects the feedback pin of power management integrated circuit U2; Feedback circuit is compared the virtual voltage of the output of low frequency current rectifying and wave filtering circuit with the reference voltage that voltage stabilizing circuit produces, feed back to U2.

2, LED desk lamp according to claim 1, it is characterized in that: above-mentioned power management integrated circuit U2 is VIPER22A, feedback circuit comprises resistance R 3 and photoelectrical coupler U1, and U1 is with the error of output voltage, and the feedback end that changes into signal of telecommunication input U2 again is the 3rd pin; Voltage stabilizing circuit is made up of voltage-stabiliser tube U3, resistance R 4, R5, R6, capacitor C 6, and the negative pole of U1 transmitting terminal connects the K utmost point of U3.

3, LED desk lamp according to claim 1 and 2, it is characterized in that: voltage stabilizing circuit also connects a brightness regulating circuit, this brightness regulating circuit is formed by regulating resistance R 9, resistance R 7 and capacitor C 8, and C8 is connected in parallel on R7, the R9, and is connected between the resistance R 6 and low pressure ground in the voltage stabilizing circuit.

4, LED desk lamp according to claim 1 and 2 is characterized in that: be connected by a socket type connector between described switching power circuit and the led light source, wherein led light source is in series by a plurality of light-emitting diodes and current-limiting resistance.

5, LED desk lamp according to claim 3 is characterized in that: be connected by a socket type connector between described switching power circuit and the led light source, wherein led light source is in series by light-emitting diode and current-limiting resistance.