Driver and lighting device for driving a chain of multiple light-emitting loads

Abstract

The present invention relates to a driving device and an illumination device for driving a plurality of light-emitting load chains, wherein the driving device comprises: a converter connected to each of the plurality of light-emitting load chains, for receiving and converting a power supply voltage, and outputting an output current for the plurality of light-emitting load chains; and a controller connected to each of the plurality of light-emitting load chains, for controlling a ratio of an input current to an output current provided to each light-emitting load chain to match a predetermined ratio allocated to each light-emitting load chain.

Description

[0001] This application is a divisional application of the invention patent application with the application date of September 22, 2017, application number 201710868682.1, and invention name “Driving device and lighting device for driving multiple light-emitting load chains”. Technical Field

[0002] The invention relates to a driving device for driving a plurality of light-emitting load chains and an illuminating device comprising the driving device. Background Art

[0003] In order to enable the same lighting device to be applied in a variety of different application environments, it may be required that the lighting device can generate light of different color temperatures or different colors according to a variety of different application environments, so that the manufacturing cost of the lighting device can be saved and the application range of the lighting device can be expanded without replacing the light source or optical components of the lighting device. In the application of such adjustable color temperature or adjustable color lighting devices, multi-channel DC drivers are often used, such as for LED lighting devices. In the prior art, in order to realize a multi-channel driving device, a switch mode power supply can be used, or a plurality of switch components can be set in each channel, or a closed-loop control can be used to sample the current signal in each channel for subsequent adjustment. The multi-channel driving device of the prior art may also require that the operating frequency of the channel is synchronized with the switching frequency of the converter of the driving device. In addition, a plurality of converters are usually provided in a traditional multi-channel DC driver, and the plurality of converters correspond to a plurality of DC channels respectively. However, the driver designed according to the prior art and the lighting device obtained thereby are not only expensive but also large in size. Summary of the invention

[0004] The present invention provides a novel driving device for driving multiple light-emitting load chains and an illumination device including the driving device. The driving device according to the present invention supports the application of DC multi-channels, has a simple structure, and is low in cost, and does not require the use of closed-loop control to actively sense specific parameters in each channel for subsequent adjustment.

[0005] One of the objects of the present invention is achieved by a driving device for driving a plurality of light-emitting load chains, wherein the driving device comprises: a converter connected to each of the plurality of light-emitting load chains, for receiving and converting a power supply voltage, and outputting an output current for the plurality of light-emitting load chains; and a controller connected to each of the plurality of light-emitting load chains, for controlling the ratio of the input current to the output current provided to each light-emitting load chain to match a predetermined ratio assigned to each light-emitting load chain. The driving device according to the present invention has a simple structure and is capable of modulating the input current in each channel, and the input current in each channel is controlled by the same driving device so that the sum of the lighting effects of the light-emitting load chains of the plurality of channels meets the expected lighting effect. Thus, without changing the load and the driving device, the same driving device can be used to achieve lighting effects with different color temperatures or colors.

[0006] According to a preferred embodiment of the present invention, each light-emitting load chain includes: a switch unit and a light-emitting unit, wherein the switch unit is used to switch the light-emitting unit; and the controller is also used to control the switch unit. The switch unit can be switched on and off according to a control signal of the controller to adjust the current flowing through the light-emitting load chain of each channel and the lighting effect generated by the light-emitting load chain of each channel.

[0007] According to a further preferred embodiment of the present invention, the switch units corresponding to each of the plurality of light-emitting load chains are independent of each other. The controller may send control signals to the plurality of channels simultaneously or sequentially to adjust the current flowing through each channel. The control of one of the plurality of channels does not affect the control of the controller over another channel. In other words, when one of the channels is adjusted, the other channel may be turned on or off according to the control signal of the controller, and when one of the channels fails, the other channels will not be affected by the failure of the channel and can continue to operate normally. In this case, the remaining channels that can operate normally can provide lighting effects sufficient to compensate for the failed channel according to the control signal.

[0008] According to a further preferred embodiment of the present invention, the controller provides a pulse width modulation control signal to the switch unit of each light-emitting load chain, wherein the pulse width modulation control signal is used to adjust the predetermined ratio. The pulse width modulation control signals provided to the plurality of light-emitting load chains have different duty cycles, so that the plurality of light-emitting load chains have different conduction controls, and the lighting effects generated by each light-emitting load chain can be superimposed to obtain the overall lighting effect of the final lighting device.

[0009] According to a further preferred embodiment of the present invention, the switch unit includes: a transistor, a first resistor, a second resistor and a first diode; and the light emitting unit includes: a capacitor, a light emitting diode and a second diode; wherein the cathode of the first diode is connected to the control electrode of the transistor through the first resistor, one end of the second resistor is connected to the node between the first resistor and the control electrode, and the other end is connected to the anode of the first diode, and the cathode of the second diode is connected to the working electrode of the transistor through the capacitor, and the light emitting diode is connected to both ends of the capacitor. Each light emitting load chain may include only one switch element, one reverse current protection diode, one output capacitor and one light emitting diode, wherein the switch element is controlled by a pulse width modulation control signal provided by a controller, that is, for example, when the control signal is a high level signal in a cycle, the switch element is opened to conduct the current path; when the control signal is a low level signal in a cycle, the switch element is closed to cut off the current path. This makes each light emitting load chain have an extremely simple and low-cost structure, and can further reduce the cost and size of the lighting device including the driving device and multiple light emitting load chains.

[0010] According to a preferred embodiment of the present invention, the controller is further used to control the sum of the input currents passing through each light-emitting load chain to be equal to the output current. The controller selectively turns on part or all of the light-emitting load chains in the plurality of light-emitting load chains, and further makes the sum of the duty cycles of the pulse width modulation signals used to control each light-emitting load chain to be 100%.

[0011] According to a preferred embodiment of the present invention, the controller is further used to control only one of the multiple light-emitting load chains to be turned on each time. In this case, when one of the multiple light-emitting load chains is turned on, the other light-emitting load chains will be turned off, which ensures that the total output current is distributed to each load chain in a controllable manner.

[0012] According to a preferred embodiment of the present invention, the controller is further used to control the conduction time periods of at least two of the multiple light-emitting load chains to overlap, be the same, or be different. The multiple light-emitting load chains can be turned on or off at the same time, that is, when one of the light-emitting load chains is turned on or off, the other light-emitting load chains are turned on or off. Thus, the final lighting effect formed by the multiple light-emitting load chains depends on all the light-emitting load chains. Thus, the final lighting effect formed by the multiple light-emitting load chains depends on some of the light-emitting load chains.

[0013] According to a preferred embodiment of the present invention, the controller is further used to control at least one of the plurality of light-emitting load chains to be initially turned on, which can protect the circuit and prevent overvoltage from being caused by no load at startup.

[0014] According to a preferred embodiment of the present invention, each light-emitting load chain has a different color temperature from each other or is composed of light-emitting elements of different colors. One of the multiple light-emitting load chains can provide the lowest color temperature, and another light-emitting load chain can provide the highest color temperature. The multiple light-emitting load chains can respectively have, for example, red, green, blue or white LED chips.

[0015] According to a preferred embodiment of the present invention, the driving device further comprises: an intermediate circuit unit connected between the converter and the plurality of light-emitting load chains. The intermediate circuit unit may be, for example, a capacitor with a small capacitance, so that the voltage of the capacitor can change rapidly with the voltage of the plurality of light-emitting load chains, and can also reduce the error of current distribution in the load chain.

[0016] According to a preferred embodiment of the present invention, the controller is further configured to control the frequency of the pulse width modulation control signal to be less than the switching frequency of the converter and greater than the power supply frequency. The frequency of the pulse width modulation control signal should be selected to avoid interference with other frequencies of the output current as much as possible, such as the power supply frequency and the switching frequency of the converter.

[0017] Another object of the present invention is achieved by a lighting device, wherein the lighting device comprises the driving device described above. The lighting device according to the present invention has a simple structure and low cost, and can change the control signal provided to each light load chain according to a specific application without replacing the driving device or the light source, so as to provide lighting with different color temperatures or colors that meet the specific application requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings constitute a part of this specification and are used to help further understand the present invention. These drawings illustrate embodiments of the present invention and are used together with the specification to explain the principles of the present invention. In the accompanying drawings, the same components are represented by the same reference numerals. The drawings show:

[0019] Figure 1 A schematic structural diagram of a driving device according to an embodiment of the present invention is shown;

[0020] Figure 2 A schematic diagram showing a circuit structure of a lighting device according to an embodiment of the present invention is shown;

[0021] Figure 3 A schematic diagram showing a pulse width modulation signal in multiple cycles of a driving device according to an embodiment of the present invention;

[0022] Figure 4 A schematic diagram showing an implementation of a pulse width modulation signal in a single cycle of a driving device according to an embodiment of the present invention;

[0023] Figure 5A schematic diagram showing another implementation of a pulse width modulation signal in a single cycle of a driving device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0024] Figure 1 1 is a schematic diagram of the structure of a driving device 100 according to an embodiment of the present invention. The driving device 100 according to the present invention comprises: a converter 2 connected to each of the plurality of light-emitting load chains 1, for receiving and converting a power supply voltage Us, and outputting an output current Io for the plurality of light-emitting load chains 1; and a controller 3 connected to each of the plurality of light-emitting load chains 1, for controlling an input current I provided to each of the light-emitting load chains 1. I The ratio to the output current is matched to a predetermined ratio assigned to each luminous load chain 1 .

[0025] For example, the converter 2 may be implemented as a buck converter or a flyback transformer, and the output current for the multiple light-emitting load chains 1 is provided by the choke of the buck converter or the secondary coil of the flyback transformer. The controller 3 may be implemented as a pulse width modulation controller 3 to provide pulse width modulation (PWM) control signals with different duty cycles to the multiple light-emitting load chains 1. Each light-emitting load chain 1 may include one or more LED lighting elements, and the LED lighting elements are powered by the direct current provided by the converter 2. The LED lighting elements of each light-emitting load chain 1 are turned on or off according to the duty cycle of the pulse width modulation signal, so that the input current I of each light-emitting load chain 1 is I The ratio of the input current Io to the output current Io meets the expected requirements. I Control is performed so that the sum of the lighting effects of the light-emitting load chains of multiple channels meets the expected lighting effect. Thus, lighting effects with different color temperatures or colors can be achieved using the same driving device without changing the load and the driving device.

[0026] The controller 3 is also used to control the frequency of the pulse width modulation control signal to be less than the switching frequency of the converter 2 and greater than the power frequency. The frequency of the pulse width modulation control signal should be selected to avoid interference with other frequencies of the output current as much as possible, such as interference with the power frequency and the switching frequency of the converter 2. For example, when the power frequency is 100 Hz and the switching frequency of the flyback converter is 33-120 kHz, in this case, the frequency of the pulse width modulation signal provided by the controller 3 may be, for example, 2-4 kHz.

[0027] Figure 2A schematic diagram of the circuit structure of a lighting device according to an embodiment of the present invention is shown. The converter 2 of the driving device provides a DC current for the lighting load of the lighting device. The lighting device also includes an intermediate circuit unit connected between the converter 2 and a plurality of light-emitting load chains, wherein the intermediate circuit unit is implemented as a capacitor with a predetermined capacitance, and the capacitor is used as an output capacitor of the lighting device. In the design of the output capacitor of a general LED driver, the output capacitor should have a large capacitance to avoid high ripple of the LED module, and the LED module should always be connected to the output capacitor. However, in the present invention, unlike the general design, the capacitance of the capacitor of the driving device is small and is designed so that the voltage of the capacitor can change rapidly with the voltage of the plurality of light-emitting load chains, which can particularly reduce the error of current distribution in the plurality of load chains. In accordance with Figure 2 In the case of two channels of the illustrated embodiment, at least one of the two channels should start conducting before the voltage of the capacitor C0 of the intermediate circuit unit rises to an overvoltage level, in particular in transient conditions such as startup.

[0028] The plurality of light load chains according to the present invention may be implemented to have the same or different circuit structures, or may differ only in the same or different LED lighting components. In the embodiment of the present invention, two light load chains with the same circuit structure are shown as an example, wherein the difference between the two light load chains may be, for example, only in the LED lighting components. In this embodiment, Figure 2 The first light-emitting load chain on the left side includes a switch unit 11 and a light-emitting unit 12, wherein the switch unit 11 includes: a transistor, a first resistor R1, a second resistor R2 and a first diode D1; and the light-emitting unit 12 includes: a capacitor, a light-emitting diode and a second diode D2. The cathode of the first diode D1 is connected to the control electrode of the transistor through the first resistor R1, one end of the second resistor R2 is connected to the node between the first resistor R1 and the control electrode, and the other end is connected to the anode of the first diode D1, and the cathode of the second diode D2 is connected to the working electrode of the transistor through the capacitor, and the light-emitting diode is connected to both ends of the capacitor. An input terminal for inputting a pulse width modulation signal is connected to the anode of the first diode D1, wherein the transistor is turned on or off according to the pulse width modulation signal at the input terminal, thereby allowing current to flow through the light-emitting diode or preventing current from flowing through the light-emitting diode. In this embodiment, the Figure 2 The second light-emitting load chain on the right has the same circuit structure as the first light-emitting load chain.

[0029] In the switch unit 11 of the first light-emitting load chain and the switch unit of the second light-emitting load chain, resistors and diodes are respectively provided, that is, the switch unit 11 of the first light-emitting load chain includes a first resistor R1, a second resistor R2 and a first diode D1, and the switch unit of the second light-emitting load chain includes a third resistor R3, a fourth resistor R4 and a third diode D3. Such a preferred design enables the conduction time of the switch units of the two channels to overlap, for example, overlap by 1 μs, as described below. Figure 5 Shown.

[0030] Only one switch may be provided in each channel of the light-emitting load chain, and the switch is used to determine whether the LED lighting element in the channel is connected to the output capacitor of the intermediate circuit unit. Moreover, the multiple channels are controlled so that the sum of the duty cycles for each channel is 1, and only one channel is connected to the output capacitor of the intermediate circuit unit at a time. Thus, the average current of each channel is determined by its corresponding duty cycle and the total output current provided by the driving device, that is, the current of the channel is equal to the output current multiplied by the duty cycle for the channel.

[0031] In addition, for example, the converter 2 is implemented as a flyback transformer with an output current of 100 kHz, and the power supply current passes through the second diode D2, the first capacitor C1, the first light-emitting diode LED1 and the first transistor T1 of the first light-emitting load chain, or the power supply current passes through the fourth diode D4, the second capacitor C2, the second light-emitting diode LED2 and the second transistor T2 of the second light-emitting load chain. In other words, depending on the conduction of the two channels, the power supply current flows through the first channel or the second channel. When the first capacitor C1 or the second capacitor C2 is connected in parallel with the capacitor C0 of the intermediate circuit unit, the first capacitor C1 and the second capacitor C2 act as the main capacitor relative to the capacitor C0 of the intermediate circuit unit. The first capacitor C1 and the second capacitor C2 can be designed according to the topology of the driving device, for example, 470 μF in a single-stage flyback application and 330 nF in a second-stage buck application.

[0032] Figure 3 FIG. 1 is a schematic diagram showing a pulse width modulation signal in multiple cycles of a driving device according to an embodiment of the present invention. Figure 3 The two pulse width modulation signals in the circuit respectively have different duty ratios, and the sum of the two duty ratios is 1. According to the first pulse width modulation signal PWM1, the ratio of the input current of the first light-emitting load chain to the output current provided by the converter matches the predetermined ratio. According to the second pulse width modulation signal PWM2, the ratio of the input current of the second light-emitting load chain to the output current of the converter matches the predetermined ratio. Moreover, Figure 3It can also be clearly seen that the polarities of the two signals are just opposite, that is, when the first pulse width modulation signal PWM1 is at a high level, the second pulse width modulation signal PWM2 is at a low level, or when the first pulse width modulation signal PWM1 is at a low level, the second pulse width modulation signal PWM2 is at a high level.

[0033] Figure 4 A schematic diagram showing one implementation of a pulse width modulation signal in a single cycle of a driving device according to an embodiment of the present invention. Figure 4 In a single cycle, when the first pulse width modulation signal PWM1 starts to change from a high level to a low level, the second pulse width modulation signal PWM2 immediately starts to change from a low level to a high level. In this case, the on-times of the two channels do not overlap.

[0034] Figure 5 A schematic diagram showing another implementation of a pulse width modulation signal in a single cycle of a driving device according to an embodiment of the present invention. Figure 5 In a single cycle, the time it takes for the first pulse width modulation signal PWM1 to change from a high level to a low level is longer, and during this time, that is, before the first pulse width modulation signal PWM1 has not changed to a low level, the second pulse width modulation signal PWM2 changes from a low level to a high level. In this case, the on-times of the two channels overlap, and the overlapping time can be changed according to the hardware design of the switch unit in each channel and the specific application requirements. In addition, for example, in an embodiment not shown in the accompanying drawings, the on-times of the two channels can completely overlap, that is, the on-times of the two channels are the same. In this case, the on and off times of the two channels are the same, that is, they are turned on and off at the same time. Therefore, the luminous intensity and color temperature of the lighting device depend on the luminous intensity and color temperature of the two channels.

[0035] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

[0036] Reference Numbers

[0037] 1 Lighting load chain 2 Converter

[0038] 3 Controller

[0039] 100 driving device 200 lighting device Us power supply voltage I O Output current I IInput current 11 Switching unit 12 Light emitting unit T1 First transistor T2 Second transistor R1 First resistor R2 Second resistor R3 Third resistor R4 Fourth resistor D1 First diode D2 Second diode D3 Third diode D4 Fourth diode C1 First capacitor C2 Second capacitor Co Intermediate circuit unit

[0040] LED1 first light emitting diode

[0041] LED2 second light emitting diode

[0042] PWM1 first pulse width modulation signal

[0043] PWM2 is the second pulse width modulation signal.

Claims

1. A driving device (100) for driving a plurality of light-emitting load chains (1), characterized in that: The driving device (100) comprises: A converter (2) connected to each of the plurality of light-emitting load chains (1), for receiving and converting a power supply voltage (Us), and providing an output current (Io) for the plurality of light-emitting load chains (1); and A controller (3) is connected to each of the plurality of light-emitting load chains (1) and is used to control an input current (I I ) and the output current (Io) are matched to predetermined ratios assigned to each of the light-emitting load chains, respectively, Each of the light-emitting load chains comprises: a switch unit (11) and a light-emitting unit (12), wherein the switch unit (11) is used to switch the light-emitting unit (12); and the controller (3) is also used to control the switch unit (11). The switch unit (11) comprises: a transistor, a first resistor, a second resistor and a first diode; and the light emitting unit (12) comprises: a capacitor, a light emitting diode and a second diode; wherein the cathode of the first diode is connected to the control electrode of the transistor through the first resistor, one end of the second resistor is connected to the node between the first resistor and the control electrode, and the other end is connected to the anode of the first diode, and the cathode of the second diode is connected to the working electrode of the transistor through the capacitor, and the light emitting diode is connected to both ends of the capacitor. Thus, by means of the first resistor and the second resistor of the switch unit and the first diode, the conduction time of the plurality of switch units of the plurality of channels of the driving device overlaps.

2. The driving device (100) according to claim 1, characterized in that: The switch units corresponding to each of the plurality of light-emitting load chains are independent of each other.

3. The driving device (100) according to claim 1, characterized in that: The controller (3) provides a pulse width modulation control signal to the switch unit (11) of each light-emitting load chain respectively, wherein the pulse width modulation control signal is used to adjust the predetermined ratio.

4. The driving device (100) according to any one of claims 1 to 3, characterized in that: The controller (3) is also used to control the input current (I I ) is equal to the output current (Io).

5. The driving device (100) according to any one of claims 1 to 3, characterized in that: The controller (3) is also used to control only one of the multiple light-emitting load chains (1) to be turned on each time.

6. The driving device (100) according to any one of claims 1 to 3, characterized in that: The controller (3) is further used to control the conduction time periods of at least two light-emitting load chains among the plurality of light-emitting load chains (1) to be partially overlapping, identical or different.

7. The driving device (100) according to any one of claims 1 to 3, characterized in that: The controller (3) is also used to control the initial state of at least one light-emitting load chain among the plurality of light-emitting load chains (1) to be turned on.

8. The driving device (100) according to any one of claims 1 to 3, characterized in that: The plurality of light load chains have different color temperatures or are composed of light-emitting elements of different colors.

9. The driving device (100) according to any one of claims 1 to 3, characterized in that: The driving device (100) further comprises: an intermediate circuit unit connected between the converter (2) and the plurality of light-emitting load chains (1).

10. The driving device (100) according to claim 3, characterized in that: The controller (3) is also used to control the frequency of the pulse width modulation control signal to be smaller than the switching frequency of the converter (2) and larger than the power supply frequency.

11. A lighting device (200), characterized in that: It comprises a driving device (100) according to any one of claims 1-10.

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