CN202941014U

CN202941014U - LED substitute for low-voltage lamp

Info

Publication number: CN202941014U
Application number: CN 201220627489
Authority: CN
Inventors: 顾天一
Original assignee: Individual
Current assignee: Individual
Priority date: 2012-11-21
Filing date: 2012-11-21
Publication date: 2013-05-15
Anticipated expiration: 2022-11-21

Abstract

An LED substitute for a low-voltage lamp is provided. Multiple LEDs (light-emitting diodes) are installed in a housing the LED substitute, wherein a multiple-reflection cover covers the housing. The LED substitute rivals a low-voltage lamp having a non-LED light source in illumination properties. A power adjusting solid-state circuit is configured to be in the housing, and provides a modulated (voltage stabilized) excitation voltage source for the LEDs. The power adjusting circuit at least has a ceramic capacitor and is connected in parallel with power output leads of the lamp. A pair of Zener diodes, positive electrodes of which are connected together, are arranged in parallel with the ceramic capacitor. The power adjusting circuit is positioned in the front of a voltage rectifier and a filter group, wherein the output of the power adjusting circuit is provided to a voltage regulator, and the voltage regulator provides modulated direct-current voltage for LED light sources. Output of the voltage regulator is under modulation by a thermal protection circuit which can limit overheating reaction to a lamp by the LEDs.

Description

The LED substitute of low-pressure lamp

Technical field

The invention relates to electrical appliance, more in particular, is that this LED substitute can be used as the substitute of the low-pressure lamp such as the MR16 Halogen lamp LED and carry out work about the LED substitute of low-pressure lamp.

Background technology

" MR " means the multipath reflection cover, is a kind of glass-reflected cover of pressurized, and inner surface (reflecting surface) is comprised of several facets, is covered with reflecting coating.These facets, by assembling the light from filament, produce concentrated light beam.The reflector of some MR lamp has smooth inner surface, rather than some facets, but generally still is referred to as the MR lamp.Typical MR light fixture has a single-ended quartz halogen filament cryptomere light source, usually by a transformerless electronic power supply power supply.The rated power that this electronic power supply should be able to meet typical MR-16 lamp requires (according to the applicable cases of illumination, its scope is 10 to 100W).The MR-16 lamp is usually with the voltage power supply lower than 120V, and nominal value is 12V.But the voltage that will find a job is 6 or the MR-16 lamp of 24V, is not difficult.For by line voltage from 120 or 240V be down to the magnitude of voltage that is suitable for these lamps, need Switching Power Supply.Most of MR-16 low-pressure lamps are equipped with a lamp socket, and lamp socket has two pins that electrically contact.But also can use other lamp sockets, for example bayonet holder or rotary locking type lamp socket.

The illumination of low-pressure lamp is generally to adopt a magnetic step-down transformer, and this transformer works in the 120V alternating current, produces the interchange output that is about 12V at about 60Hz.When can making LED work, this frequency can not produce the visible flicker of vision in its output.If but adopted transformerless Switching Power Supply, will produce such problem: electronic transformer, usually its oscillator is before connecting and to exporting a load need to exporting before generation current, this load is along with different electronic transformers changes, but the typical set value is 8-10W.Do not load on this numerical value (scope) if transformer detects, transformer can not start (starting unsuccessfully).Generally speaking, the light source of LED-based substitute gives transformer a load, and it is the ten Percent of transformer quota, lower than " ON (connection) " set point of transformer.In addition, high times of the standard 60Hz line frequency that the output frequency that the Switching Power Supply oscillator is set may provide than magnetic transformer.This frequency is sufficiently high, high in the drive circuit of LED light source, producing harmonic wave.LED has the 8-10 nanosecond rise time of (nanosecond), therefore these harmonic waves have enough amplitudes, can effectively turn on and off LED with a subharmonic frequency of oscillator frequency, thereby make LED light source produce flicker, this flicker is apparent for the people who is seeing light.

In order with LED light source, to substitute the MR-16 halogen light source, attempt.The problems referred to above that run into when adopting LED are: LED does not draw enough current activation Switching Power Supplies.In addition, Switching Power Supply may be exported the instantaneous voltage spike at any time, can damage the sensitive LED source in the LED substitute.

Therefore, we need to solve the LED substitute of the problems referred to above, are used for substituting low-pressure lamp.

Summary of the invention

This LED substitute of low-pressure lamp is the substitute of typical halogen or other non-LED light source low-pressure lamps.This LED substitute of low-pressure lamp, have typical low pressure form factor, and several LED are housed in its shell, and outer casing upper cover has a multipath reflection cover, and the illumination provided has the photocurrent versus light intensity of the low-pressure lamp that can be comparable to non-LED light source.Dispose the power adjustments solid-state circuit in shell, to LED, providing the excitation (excitation) of being regulated voltage source.This power conditioning circuitry at least has a ceramic capacitor, in parallel with the power supply output lead of lamp.A Zener diode preferably antianode connected together and power adjustments ceramic capacitor are arranged in parallel.Before power conditioning circuitry is positioned at voltage rectifier and bank of filters (its output offers a voltage regulator, and this voltage regulator provides modulated direct voltage to LED light source).The output of voltage regulator can be subject to LED being dimmed or the modulation of the thermal protection circuit that turn-offs according to temperature conditions in lamp housing.

These characteristics of the present invention and other characteristics, along with detailed description and illustration hereinafter, perspicuousness more will become.

The accompanying drawing explanation

Fig. 1 is the perspective view of low-pressure lamp LED substitute of the present invention.

Fig. 2 is the plane graph of low-pressure lamp LED substitute of the present invention.

Fig. 3 is the principle schematic of first embodiment of the drive circuit of invention low-pressure lamp LED substitute.

Fig. 4 is the principle schematic of second embodiment of the drive circuit of invention low-pressure lamp LED substitute.

Fig. 5 is the principle schematic (provide and dim compensation) of the 3rd embodiment of the drive circuit of invention low-pressure lamp LED substitute.

Similar means the consistent individual features of some accompanying drawings (illustrating) with reference to characteristic.

Embodiment

Embodiment describes

As shown in figure 14, the invention provides a kind of low-pressure lamp LED substitute.This LED substitute (10 in figure) as halogen reflector substitute has a typical low voltage bulb form factor, several LED lamps (15 in figure) are housed in its shell, outer casing upper cover has a multipath reflection cover (25 in figure), and the illumination provided has the photocurrent versus light intensity that can be comparable to Halogen lamp LED.This LED substitute (in figure 10) has a lamp socket (in figure 30), extends two from lamp socket and electrically contacts pin (figure 35).

Be arranged in power adjustments solid-state circuit in shell (in figure 305) and power adjusting circuit (in figure 310) and providing modulated excitation (excitation) voltage source to the LED lamp.Power conditioning circuitry (305) comprises at least one ceramic capacitor (C5), in parallel with output lead J1 and the J2 of the typical 12V AC power of this substitute (10).C5 is pottery preferably, in order to the mean time between failures (MTBF) MTBF with mean time between failures (MTBF) MTBF (the being approximately 50000+ hour) same order of typical LED bulb LED1-LED3 is provided.The preferred value scope of capacitor C5 be when about 50V rated value between 0.015uF.As shown in Figure 4, another embodiment provides that an antianode connects together, the Zener diode (U3 ' in figure and U4 ') in parallel with the ceramic capacitor C13 ' of power adjustments.The Zener limiting voltage preferably is located at about 19V.The preferred value scope of capacitor C13 ' be when about 50V rated value between 0.015uF.

With reference to Fig. 3, power conditioning circuitry can comprise (being preferably) all-wave voltage rectifier, by diode D1, D2, D3 and D4, formed, this voltage rectifier is connected to a bank of filters that comprises capacitor C1 and C2, make to provide the direct voltage output of the LED drive circuit U1 (it is to direct-current LED light source (15) (LED1, LED2 and LED3) power supply) to pressure regulation steady, an exemplary driving U1 can be a Maxim MAX 16820, and it provides the about 2MHz high-brightness LED that has the high-side current sensing and dim in about 5000: 1 to drive.The YIN of rectifier output is connected to the IN end (pin 1) that drives U1.Drive U1 preferably can provide for scope the adjustment output of about 5V at about 4.5 to 28V VIN input voltage.

The LED drive circuit U1 of pressure regulation (voltage stabilizing), its output can be subject to the modulation (R3 is the thermistor of a positive temperature coefficient, is the series shunt with resistor R4) of thermal protection circuit.It is controlling the charging (to LED1, LED2 and the LED3 of LED) to capacitor C4 at the input DIM (pin 3) that dims of U1, when temperature surpasses default safe threshold value in lamp housing (20 in figure), by shunt regulator U2, gradually dim and turn off LED.When power reduction preferably is located at about 60 ℃, the attenuating rate is made as and cuts down 50% power in the time of about 73 ℃, and (or maximum allowable temperature 85%) prevents unpredictalbe situation and lamp system (10 in figure) is caused to pyrolytic damage.Can be by pulse-width modulation (PWM) or linear mode by power reduction.The set point of U2 is determined by the resistance R 5 with respect to thermistor R3 and R4 and R6.

The forward bias of shunt regulator U2 is provided by the tandem compound of resistance R 1 and R2, and R1 is directly connected to positive side (plus side) VIN of filtering direct voltage.Shunt regulator output U2 is connected to CSN (the current sense pin 2) input that adjuster/LED drives U1.Adjuster/LED drives U1 output DRV (pin 5) to cause the door of the N raceway groove of metal oxide semiconductor field effect tube (MOSFET) Q1, its output presents to Schottky (Schottky) diode D8, for LED provides modulated input voltage of (voltage stabilizing).The diode of standard can be used for D8, but (Schottky) diode that preferably adopts Schottky, because its forward drop is lower, that is to say, the Schottky diode is approximately 0.25V, and the diode of standard is approximately 0.6V.

Voltage drop on series resistance R1 and R2 is providing modulated direct voltage of (voltage stabilizing) to several LED (being LED1, LED2 and the LED3 of LED).Resistance R 7 and capacitor C 3 are from adjuster or drive the ground connection (pin 4) chip U1 that enough VCC (pin 6) isolation are provided.Inductor L1 works together with filtering capacitor C1-C2, and additional DC pulse filtering is provided.But between LED3 and Q1, inductance value can be down to about 50 μ H due to L1, thus maintain one can with the small-sized form factor of the form factor compatibility of MR-16 lamp.

Referring again to Fig. 4, on figure, illustrate: the present invention can amplify in proportion, holds the more LED lamp of more number, the array for example be comprised of 10 LED (LED1 to LED10).The ceramic capacitor C13 ' that the Zener diode U3 ' of transient state restriction and U4 ' are parallel to power adjustments above was discussed.This C13 ', as the C5 in Fig. 3, the high-frequency component of exporting for the electronic switch power at J1 ' and J2 ' provides a path, so that electronic power supply can sense enough loads, makes himself to connect.In order to increase the efficiency of voltage commutation, the Schottky provided (Schottky) diode D1 ', D2 ', D3 ' and D4 ' have low V _fValue (being approximately 0.25V).

Filter capacitor C1 ' preferentially adopt tantalum material to make to C9 ', and its mean time between failures (MTBF) (MTBF) should be for example, with the mean time between failures (MTBF) of typical LED array (: LED1 to LED10) at the same order of magnitude.R1 ' is identical with the function of R1 in Fig. 3 and R2 with R2 '.Yet, LED drive circuit U1 ' also further by with resistance R 1 ' with the capacitor C 14 of R2 ' parallel connection ' be subject to the exchanging protection of transient state input.

The input 1 of LED drive circuit U1 ' ' to 6 ' similar with the connected mode in Fig. 3.But; except the heat dissipation protection provided by shunt regulator U2 ' and related resistors R4 ', R5 ' (thermistor) and R6 ', the circuit of LED lamp as shown in Figure 4 also carries out voltage loss protection by R7 ', R8 ', C10 ' and transistor Q2 ', and (its output also is connected to dim and inputs DIM (pin 3 ').Transistor Q2 ' has a pullup resistor R3 ', and drives the VCC input of U1 ' to have a pullup resistor R10 '.DC-isolation is over the ground provided by capacitor C12 '.

Adjuster/LED drives U1 ' output DRV (pin 6 ') to cause the door of N NMOS N-channel MOS N field effect transistor (MOSFET) Q1, its output is presented to diode D5 ', for LED array (LED1 ' to LED10 ') provides modulated input voltage VIN of (voltage stabilizing).Capacitor C 11 ' be parallel to LED array, make voltage more steady, and the payment LED1 ' of array branch is to LED5 ' and the LED6 ' of array branch to the voltage difference that may produce between LED10 '.Inductance L 1 ' work together with C1 '～C9 ', provide additional DC pulse filtering.But between R1 ' and Q1, inductance value can be down to about 50 μ H due to L1 ', thus maintain one can with the small-sized form factor of the form factor compatibility of MR-16 lamp.

With reference to Fig. 5, this low-pressure lamp LED substitute can comprise and dim compensating circuit, and this compensating circuit is comprised of diode D13, resistance R 13 and capacitor C 4.This dims compensating circuit and has adopted low tension minor power supply and electronic low pressure dimmer, can carry out flicker free and dim.(alternating current) rear end cutting type dimmer copped wave AC wave shape when the 60Hz cycle starts, dim low that degree can not be supplied with enough voltage so that drive chip U1MAXI 6820 (or equivalent devices) to remain on "on" position or wake-up states.Because the electric current that suddenly is reduced to each LED, driving chip " enter sleep " at every turn, can have influence on the output of LED.When the voltage of transporting to chip is turned down to lower than the 8V direct current, " connect-turn-off " circulation of this kind of LED output can become apparent shake and flicker.Dim compensating circuit and be connected to CSN and the DIM input that drives U1.

Fig. 5 is equal in fact Fig. 3, only at pin 2 places that drive chip U1, has added resistor R13, between capacitor C4 and shunt regulator U2, has been connected diode D13.Diode D13, resistor R13 and capacitor C4 are the configurations that drives chip U1 that is connected to of exemplary (typical case), can realize the required compensation that dims, and avoid the scintillation of lamp in dimming process.Dim compensating circuit and adopted (alternating current) rear end cutting type dimmer, thereby make capacitor C4 by the electric current of feeding of the main tributary after capacitor makes capacitor C4 receive continuously the 12V direct current and to store it from pulsation continuously.So just can make LED MR 16 flicker-freely dimmed.Capacitor C4 delivers to electric current to drive chip U1, even while guaranteeing to be adjusted to extremely secretly, voltage also never is down to critical level.

In addition, diode D13 plays the effect of a unidirectional valve, guarantees when capacitor C4 discharges, electric current can not be fed back to main circuit.

In addition, can calculate the numerical value of trying to achieve resistor R13, guarantee that capacitor C4 can not discharge too fast, that is to say, R13 and C4 form a R-C loop, and in loop, capacitor C4 keeps enough residual charges, are enough to make chip U1 keep " waking " state in low pressure cycle.Moreover optional value of getting resistor R13, make resistor R13 protection chip U1 not receive excessive drive current.

Be only below concrete exemplary applications of the present invention, protection scope of the present invention is not constituted any limitation.In addition to the implementation, the present invention also can have other execution mode.All employings are equal to the technical scheme of replacement or equivalent transformation formation, all within the present invention's scope required for protection.

Claims

1. a low-pressure lamp LED substitute comprises following these parts:

A kind of shell;

Several light-emitting diodes in shell;

Semitransparent reflector lens on shell, these semitransparent reflector lens will be focused on from light-emitting diode, the light that goes out from the shell loss;

The electrical contact that makes the lamp energising in case back;

The LED drive circuit of voltage commutation-pressure regulation, the licensed conduct of this LED drive circuit is inputted the constant-current voltage-stabilizing of low-voltage AC generation and its response as the output to LED from transformer;

A ceramic capacitor of electric cross-over connection low-voltage alternating-current input, this ceramic capacitor provides enough loads to transformer, makes transformer connect input;

Be connected to the thermal protection circuit of the LED drive circuit of voltage commutation-pressure regulation, this thermal protection circuit reduces at the power of the near light-emitting diode of energy when the LED lamp surpasses the preset threshold temperature value;

The zener diode in parallel with ceramic capacitor at the low-voltage alternating-current input, the anode of this zener diode connects together, and negative electrode is connected on the terminal separately of low-voltage alternating-current input; And

A kind of between thermal protection circuit and voltage commutation-pressure regulation LED drive circuit, connect dim compensating circuit; it can provide enough voltage to LED drive circuit, makes the flicker free state that can keep light-emitting diode when thermal protection circuit is reduced to the power of light-emitting diode.

2. LED substitute according to claim 1, wherein, shell and MR-16 form factor compatibility.

3. LED substitute according to claim 1, wherein, voltage rectifying circuit comprises several diodes, and with a kind of way of full-wave rectification configuration.

4. LED substitute according to claim 1, also comprised a Schottky (Schottky) diode, and this diode is arranged in the output of the voltage regulator/drive part of voltage commutation-pressure regulation LED drive circuit with electric means.

5. LED substitute according to claim 1, also further comprised the compensating circuit that dims that dims input that is connected to above-mentioned voltage commutation-pressure regulation LED drive circuit.

6. LED substitute according to claim 1, wherein, the voltage commutation of LED drive circuit part has also further comprised the several tantalum capacitors with parallel way cross-over connection rectifier output end.

7. LED substitute according to claim 1, wherein, thermal protection circuit has the configuration that pulse-width modulation dims.

8. LED substitute according to claim 1, wherein, thermal protection circuit is the linearity light adjusting configuration.

9. LED substitute according to claim 1, wherein, several light-emitting diodes are arranged side by side with electric means, and a smmothing capacitor is parallel to LED row.

10. LED substitute according to claim 1, wherein, ceramic capacitor its value when about 50V rated value is about 0.015uF.

11. LED substitute according to claim 1, wherein, a zener diode provides slicing (amplitude limit) effect of about 19V.

12. a low-pressure lamp LED substitute comprises following these parts:

A kind of shell;

Several light-emitting diodes in shell;

The electrical contact that makes the lamp energising in case back;

The LED drive circuit of voltage commutation-pressure regulation, the licensed conduct of this LED drive circuit is inputted the constant-current voltage-stabilizing of low-voltage AC, generation and its response as the output to LED from transformer, wherein, the voltage regulator/drive part of voltage commutation-pressure regulation LED drive circuit comprises that the high-brightness LED of about 2MHz drives (light modulation that it has high-side current sensing and about 5000: 1);

Be connected to the thermal protection circuit of the LED drive circuit of voltage commutation-pressure regulation, this thermal protection circuit reduces at the power of the near light-emitting diode of energy when the LED lamp surpasses the preset threshold temperature value; And

13. a low-pressure lamp LED substitute comprises following these parts:

A kind of shell;

Several light-emitting diodes in shell;

The electrical contact that makes the lamp energising in case back;

Be connected to the thermal protection circuit of the LED drive circuit of voltage commutation-pressure regulation, this thermal protection circuit reduces at the power of the near light-emitting diode of energy when the LED lamp surpasses the preset threshold temperature value.Wherein, thermal protection circuit starts to reduce power in the time of about 60 ℃, and it falls lower powered degree and is: maximum allowable temperature about 85% the time cut down power 50%; And a kind of between thermal protection circuit and voltage commutation-pressure regulation LED drive circuit, connect dim compensating circuit; it can provide enough voltage to LED drive circuit, makes the flicker free state that can keep light-emitting diode when the power of the near light-emitting diode of thermal protection circuit reduces.