CN110662324A

CN110662324A - Driver and lighting module

Info

Publication number: CN110662324A
Application number: CN201810688420.1A
Authority: CN
Inventors: 张清富; 李志峰; 杨旭生
Original assignee: Landes Vance
Current assignee: Landes Vance; Ledvance GmbH
Priority date: 2018-06-28
Filing date: 2018-06-28
Publication date: 2020-01-07
Also published as: DE102019117474A1

Abstract

The invention relates to a driver (100) for a lighting module, and to a lighting module having such a driver (100) and a light emitting element (300). The driver has driver inputs (P1, P2, P3, P4) for receiving a supply voltage output by an electronic control device (ECG). The driver also has driver outputs (301,302) for supplying power to the light emitting elements. Furthermore, the driver has a bridge (110) for rectifying the supply voltage and providing a rectified voltage; and a power switching transistor (135) for switching the rectified voltage to supply power on the driver output (301, 302). An LC circuit (102,104) is provided across the bridge (110) to stabilize the voltage between the driver outputs (301, 302).

Description

Driver and lighting module

Technical Field

The present invention relates to a driver for a lighting module and a lighting module comprising said driver.

Background

Fluorescent lamps have been a well-known and widely used lighting device for many years as an effective replacement for incandescent light bulbs. However, with the advent of LED lamps, more efficient and longer life lighting devices can be achieved. Furthermore, the material of LED lamps is safer compared to fluorescent lamps, since for example mercury is not needed. Therefore, there is a need for: existing fluorescent lamps are replaced with LED lamps, preferably without changing the entire luminaire or fixture.

Currently available fluorescent light fixtures typically include an electronic ballast (also known as an electronic control device, abbreviated as ECG) for regulating and limiting the current supplied to the fluorescent lamp. Therefore, an LED lamp (LED retrofit lamp) for replacing a fluorescent lamp or a halogen lamp needs to be compatible with ECG.

Fig. 1 shows a driver for an ECG designed to be compatible with power supplies in different regions, including europe, middle east and africa (EMEA) and the asia-pacific (APAC) regions. The ECG provides outputs P1, P2, P3 and P4, which are connected to the driver shown in fig. 1 through

filaments

222, 224, 226 and 228, respectively. The ECG supplies the high frequency signal to the driver via the relay contactor (or switch) 230 and the capacitor 240 through the ECG output terminals P1 to P4. The energy from the ECG is used to power a ballast provided across the

driver outputs

301, 302. The ECG may be a smart ECG that can drive different fluorescent tubes, such as 28W, 35W, 49W and 80W fluorescent tubes. The smart ECG can vary the output current of the smart ECG based on the resistance detected by

filaments

222, 224, 226 and 228. As a result, the lower the fluorescent lamp power, the higher the frequency of the smart ECG output.

The driver of fig. 1 is a passive circuit. It includes

bridge diodes

112, 114, 116 and 118. They form a bridge connected in parallel to the input filter capacitor 120 and the resistor 132.

Another resistor 134 together with a capacitor 138 and a diode 139 controls the gate of a power switch transistor 135. The drain of the power switch transistor 135 is connected to the first output 301 of the driver via a resistor 136. The source of the power switch transistor 135 is connected to the second output 302 of the driver through the relay coil 130 arranged in parallel with the filter capacitor 180.

The voltage between the driver outputs 301,302 depends on the energy provided by the ECG and the capacitance value of the capacitor 240. The capacitance value Z of capacitor 240 varies with the frequency f of the smart ECG output according to the following formula:

as a result, the capacitance of capacitor 240 decreases as the frequency output by the smart ECG increases. The reduced capacitance will in turn cause the voltage between the driver outputs 301,302 to rise. This voltage may rise beyond the specified voltage range of the lighting element connected between

terminals

301, 302. As a result, the power switching transistor 135 may overheat and/or fail.

In the prior art, solutions to this problem have been proposed, as shown in fig. 2. The driver comprises a comparator 140, which comparator 140 outputs a high voltage to the power switching transistor 135 when the voltage between the driver outputs 301,302 exceeds a predetermined value. The filter capacitor 180 provides a voltage to the lighting element connected between terminals 301,302 while the freewheeling diode 185 prevents current from flowing back to the power switch transistor 135 and

bridge diodes

112, 114, 116, 118. In summary, the provision of comparator 140 may help to maintain the voltage across relay coil 130 within a specified range.

Disclosure of Invention

In view of the above-mentioned drawbacks of currently available lighting modules, it is an object of the present invention to provide a driver for LED lamps to retrofit existing lighting modules (e.g. currently available fluorescent light fixtures comprising an ECG) to be compatible with LED lamps.

The driver is designed to be compatible with smart ECG and to improve the stability of the voltage delivered by the driver to the LED lamp. This is achieved by automatically adjusting the output voltage based on the frequency of the input voltage.

The driver may also be cheaper and/or involve simpler circuitry than prior art drivers. Furthermore, the design of the driver may be more compact than the prior art drivers discussed above, especially when the LC circuit of the driver is implemented using Surface Mounted Devices (SMDs).

This problem is solved by a driver for a lighting module according to the independent claim.

Preferred embodiments are given by the dependent claims, the description and the figures.

Accordingly, there is provided a driver for a lighting module, comprising: a driver input for receiving a supply voltage for the ECG output; and a driver output for supplying power to the light emitting element. The bridge rectifies the power supply voltage and provides a rectified voltage; and a power switching transistor switches the rectified voltage to supply power on the driver output. Further, an LC circuit is provided across the bridge for stabilizing the voltage between the driver outputs.

In a first aspect, a driver is provided, wherein the bridge comprises a first bridge input and a second bridge input, wherein an LC circuit is connected between the first bridge input and the second bridge input. This may enable the LC circuit to at least partially cancel out possible changes in capacitance produced by the smart ECG.

According to another aspect, a driver is provided, which is a passive driver. This design may provide a simpler, lower power solution for compatibility with smart ECGs.

According to any of the above aspects, the driver may be used to drive an LED lighting module, such as an LED retrofit tube. The LED modified tube can be a T5LED modified tube or a T8LED modified tube.

It is a further object of the invention to provide a lighting module comprising a driver and a light emitting element, wherein the light emitting element is coupled to a driver output of the driver. The driver is preferably the driver described above. That is, all features disclosed in relation to the driver are also disclosed in relation to the lighting module and vice versa.

The light-emitting element preferably comprises or is a light-emitting diode (LED). The lighting module may be adapted to be placed in an LED lamp.

Drawings

The present disclosure will be more readily understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

figure 1 is a schematic view of a first type of driver for a lighting module known in the prior art,

figure 2 is a schematic view of a second type of driver for lighting modules known in the prior art,

figure 3 is a circuit diagram of an LC circuit,

figure 4 is a graph of the response of the LC circuit shown in figure 3,

figure 5 is a schematic diagram of an exemplary embodiment of a driver for a lighting module,

FIG. 6 is a graph of the voltage between the driver outputs of the driver of FIG. 1, an

Fig. 7 is a graph of the voltage between the driver outputs for the embodiment of the driver shown in fig. 5.

Detailed Description

In the following, exemplary embodiments of the driver and the lighting module will be explained in more detail with reference to the drawings. The same or similar elements or elements having the same effect are denoted by the same reference numerals, and repetitive description thereof may be omitted in order to avoid redundancy. The drawings and the dimensional relationships of the elements shown in the drawings to one another should not be considered to be drawn to scale. However, the individual elements may be illustrated with exaggerated dimensions for better illustration and/or better understanding.

Fig. 3 shows an LC resonant circuit including an inductor L102 and a capacitor C104. Such a resonant circuit produces a characteristic impedance that varies with the input frequency and is lowest at the resonance point, as shown in fig. 4. When the input frequency f is higher or lower than the resonance point, the characteristic impedance Z of the LC circuit increases.

In fig. 5, an exemplary embodiment of a driver 100 for a lighting module is shown. The drive is similar in some respects to the prior art drive of figure 1. However, the driver of fig. 5 differs in that: it includes LC circuits 102,104 within its bridge rectifier (or rectifier bridge) 110.

In particular, the bridge rectifier 110 comprises a first bridge input 111 and a second bridge input 113 and a first bridge output 115 and a second bridge output 117. The first bridge input 111 is connected to the first bridge output 115 via a bridge diode 112. The second bridge input 113 is connected to the first bridge output 115 via a bridge diode 114. The second bridge output 117 is connected to the first bridge input 111 via a bridge diode 116. The second bridge output 117 is connected to the second bridge input 113 via a bridge diode 118.

The LC circuits 102,104 are connected between a first bridge input 111 and a second bridge input 113. The LC circuits 102,104 enable some of the energy received from the smart ECG to pass through. By choosing an appropriate frequency for the resonance point of the LC circuits 102,104, the resulting impedance will be lower when the smart ECG produces a frequency near the resonance point. This results in the voltage between the output terminals 301,302 remaining relatively stable. More specifically, this results in the output voltage remaining within a specified range, which for some LEDs may be between 5V and 35V. This therefore prevents thermal problems from occurring that could damage or destroy the power switch transistor 135.

Fig. 6 and 7 show the difference in output voltage between the driver of fig. 1 and the driver of fig. 5. In particular, fig. 6 shows that the voltage between the driver outputs 301,302 of the driver of fig. 1 is about 65V. Fig. 7 shows that the voltage between the driver outputs 301,302 of the driver of fig. 5 fluctuates only slightly around a value of 18.6V. It is thus clear that the embodiment of fig. 5 produces an output voltage that remains stably within the specified range.

It is obvious to the person skilled in the art that the embodiment shown merely describes one example of the possibilities. Thus, the embodiments discussed herein should not be construed as limiting these features and configurations. Any possible combination and configuration of the features described may be selected in accordance with the scope of the invention.

List of reference numerals

P1, P2, P3, P4 ECG output terminals

100 driver of lighting module

102 inductor

104 capacitor

110 bridge rectifier

111. 113 a first bridge input and a second bridge input

115. 117 first and second bridge outputs

112. 114, 116, 118 bridge diode

120 input filter capacitor

130 relay coil

132 resistor

134 resistor

135 power switching transistor

136 resistor

138 capacitor

139 diode

140 comparator

142 diode

143 resistor

144 resistor

145 resistor

146 resistor

148 resistor

180 filter capacitor

185 freewheel diode

222. 224, 226, 228 filament

230 relay contactor

240 filter capacitor

301. 302 first driver output and second driver output

Claims

1. A driver (100) for a lighting module, comprising:

driver inputs (P1, P2, P3, P4) for receiving a supply voltage output by an electronic control device (ECG);

a driver output (301,302) for supplying power to the light emitting element;

a bridge (110) for rectifying the supply voltage and providing a rectified voltage; and

a power switching transistor (135) for switching the rectified voltage to supply power on the driver output (301, 302);

the method is characterized in that:

the driver comprises an LC circuit (102,104), the LC circuit (102,104) being arranged across the bridge (110) to stabilize the voltage between the driver output terminals (301, 302).

2. The driver (100) as defined in claim 1, wherein the bridge (110) comprises a first bridge input (111) and a second bridge input (113), wherein the LC circuit (102,104) is connected between the first bridge input (111) and the second bridge input (113).

3. The driver (100) of claim 1 or 2, wherein the driver is a passive driver.

4. A lighting module comprising a driver (100) according to any one of the preceding claims and a light emitting element, wherein the light emitting element is coupled to a driver output (301,302) of the driver (100).