Control circuit for a lighting device with light-emitting diodes

Abstract

A control circuit for an LED lighting device comprising a plurality of LED groups (LED1-LED4) for emitting light in accordance with a rectified voltage, the control circuit comprising: a rectified voltage sensor unit (16) configured to detect the rectified voltage and provide a sensor signal; and a control unit (14) configured to compare reference voltages (VREF1-VREF4) with a current sensor voltage corresponding to a current intensity based on the light emission of the LED groups (LED1-LED4), wherein the reference voltages (VREF1-VREF4) are associated with the respective LED groups (LED1-LED4) and have different levels that are set depending on the sensor signal, and to provide a current path associated with the light emission states of the LED groups (LED1-LED4), wherein the levels of the reference voltages (VREF1-VREF4) are set to be inversely proportional to the rectified voltage, thereby ensuring uniform brightness by compensating for voltage fluctuations, and where the current strength on the current path is controlled depending on the sensor signal.

Description

Technical area

[0001] The present disclosure relates to an LED lighting device, and more particularly to a control circuit for an LED lighting device that compensates power for light emission by a lamp including LEDs. State of the art

[0002] According to the recent development of lighting technology, LEDs are used as a light source to reduce energy consumption.

[0003] A high-brightness LED differs from other light sources in terms of various properties, such as energy consumption, lifespan and light quality.

[0004] However, a lighting device that uses LEDs as a light source requires a large number of additional circuits because LEDs are driven by a constant current.

[0005] To solve the problem described above, an AC direct control type lighting device (AC direct type) was developed.

[0006] The AC direct-type LED lighting device generates a rectified voltage from a standard AC power supply and powers an LED. Because the AC direct-type LED lighting device directly uses the rectified voltage as an input voltage, without the use of an inductor and capacitor, the AC direct-type LED lighting device has a satisfactory power factor.

[0007] Generally, an LED lamp of the LED lighting device includes a large number of LEDs connected in series.

[0008] The LED lighting device can be used in various power supply environments. The power supply conditions may vary from building to building, and they may differ from region to region or country to country. Furthermore, in addition to the conditions described above, the LED lighting device may be located in a temporarily unstable power supply environment.

[0009] In the power supply environment described above, the LED lighting device may receive a rectified voltage that is lower than the rectified voltage intended to power the lamp. In this case, the LED lighting device may not be able to emit light at the intended brightness.

[0010] In addition, when the LED lighting device is operated in an unstable power supply environment, the LED lighting device may not maintain uniform brightness due to a temporary drop in the rectified voltage.

[0011] Thus, a conventional LED lighting device may not be able to maintain uniform brightness due to the environmental factors described above.

[0012] The prior art relevant to the present invention is given by KR 10-1272463 B1, WO 2013 / 100 736 A1, US 2012 / 0 217 887 A1, CN 103 260 300 A and KR 10-1175934 B1. REVELATIONTechnical problem

[0013] Various embodiments relate to a control circuit for an LED lighting device capable of ensuring uniform luminance by compensating for power supplied to a lamp in response to a power supply environmental factor in a building, region, or country, or a temporarily unstable power supply environmental factor. Technical solution

[0014] The invention is defined by the subject matter of the appended independent claims. Particular embodiments are defined by the additional features of the appended dependent claims. In one embodiment, a control circuit for an LED lighting device is provided, which comprises a plurality of LED groups for emitting light in accordance with a rectified voltage.The control circuit may include: a rectified voltage sensor unit configured to detect the rectified voltage and provide a sensor signal; and a control unit configured to compare reference voltages with a current sensor voltage corresponding to a current intensity based on the light emission of the LED groups. The reference voltages are associated with the respective LED groups and have a level adjusted depending on the sensor signal, and provide a current path associated with the light emission states of the LED groups. The current intensity on the current path can be controlled depending on the sensor signal.

[0015] In another embodiment, a control circuit for an LED lighting device is provided, which comprises a plurality of LED groups for emitting light according to a rectified voltage. The control circuit may comprise: a rectified voltage sensor unit configured to provide a sensor signal obtained by detecting the rectified voltage; a rectified voltage compensation circuit configured to generate, depending on the sensor signal, a compensation signal corresponding to changes in the power supplied to the plurality of LED groups; a reference voltage control unit configured to convert the compensation signal and provide reference voltages associated with the respective LED groups;and a plurality of switching circuits provided for the respective LED groups, configured to compare the reference voltages with a current sensor voltage corresponding to a current intensity based on the light emission of the LED groups, and providing a current path associated with the light emission states of the LED groups. The reference voltages can be controlled depending on changes in the power supplied to the plurality of LED groups, such that the current intensity on the current path is controlled. Beneficial effects

[0016] According to embodiments of the present invention, the control circuit of the LED lighting device can compensate for a power supply environmental factor in a building, region, or country, or for a temporarily unstable power supply environmental factor, by adjusting the current. Thus, the control circuit can compensate for the light emission power of a lamp using LEDs.

[0017] In addition, since the control circuit compensates the power to emit the lamp that supplies the LEDs for light emission, the LED lighting device can emit light with uniform brightness in different power supply environments, making it possible to maximize the reliability of products. Short description of the drawing Fig. 1 is a circuit diagram illustrating a control circuit for an LED lighting device according to an embodiment of the present invention. Fig. Fig. 2 is a waveform diagram for describing the operation of the control circuit according to the embodiment in Fig. 1. The Fig. 3A and Fig. 3C show waveform diagrams describing a rectified voltage, a sensor signal, and a peak sensor signal. Fig. Figure 4 shows a graph illustrating changes in reference voltages. Fig. 5 is a graph illustrating that the power is changed by compensation according to the embodiment of the present invention. Fig. 6 is a block diagram illustrating a compensation circuit according to another embodiment of the present invention. Fig. Figure 7 is a graph illustrating that the performance is improved by the compensation according to the embodiment in Fig. 6 is changed. Invention mode

[0018] In the following, exemplary embodiments of the present invention are described in detail with reference to the accompanying drawings. The terms used in the present description and claims are not limited to typical dictionary definitions, but are to be interpreted within the context of the meanings and concepts inherent in the technical idea of ​​the present invention.

[0019] The embodiments described in the present specification and the configurations illustrated in the drawings are preferred embodiments of the present invention and do not represent the complete technical idea of ​​the present invention. Thus, various equivalent solutions and modifications may be provided, suitable for replacing the embodiments and configurations at the time of filing this application.

[0020] The present invention discloses embodiments configured to compensate for a power change caused by a fluctuation in the rectified voltage due to a power supply environment using a current.

[0021] A control circuit of an LED lighting device according to an embodiment in Fig. 1 is arranged to perform the following: a current control function for light emission of a lamp 10 and a function for compensating for changes in the power supplied to the lamp 10 depending on fluctuations in the rectified voltage caused by an environmental factor of the power supply.

[0022] With reference to Fig. 1, the LED lighting device according to the embodiment of the present invention may include a lamp 10, a power supply unit, and a control unit 14. The power supply unit provides a rectified voltage obtained by converting a commercial voltage for the lamp 10, and the control unit 14 provides a current path for the light emission of the lamp 10.

[0023] The lamp 10 comprises LEDs connected in series and divided into several groups. The respective groups of the lamp 10 emit light sequentially according to a ripple of the rectified voltage provided by the power supply unit, as shown in Fig. 2 is shown.

[0024] Fig. Figure 1 shows that the lamp 10 comprises four LED groups LED1 to LED4 connected in series, whereby the number of LED groups can be varied according to a designer's specifications. Each of the LED groups LED1 to LED4 can comprise multiple LEDs connected in series, parallel, or series-parallel. For ease of description, the multiple LEDs are represented by a single diode symbol.

[0025] The power supply unit is designed to rectify an external AC voltage and output the rectified voltage.

[0026] The power supply unit may include an AC voltage source VAC having an AC voltage, and a rectifier circuit 12 for outputting a rectified voltage by rectifying the AC voltage. The AC voltage source VAC may include a commercially available power supply.

[0027] The rectifier circuit 12 performs full-wave rectification of a sinusoidal AC voltage from the AC voltage source VAC and outputs the rectified voltage. Thus, as shown in Fig. 2, the rectified voltage has a ripple with which its voltage level rises / falls based on the half cycle of the AC voltage.

[0028] The control unit 14 performs current control for the light emission of the respective LED groups LED1 to LED4. The control unit 14 can be implemented as a chip and configured to provide a current path through an external current sensor unit comprising a current sensor resistor Rs, one end of which is grounded.

[0029] According to the configuration described above, the LED groups LED1 to LED4 of the lamp 10 are sequentially turned on or off depending on the rises or falls of the rectified voltage. When the rectified voltage rises to successively reach the light emission voltages V1 to V4, the control unit 14 selectively provides a current path for light emission by the LED groups LED1 to LED4.

[0030] The light emission voltage V4 of the LED group LED4 is defined as a voltage to drive each of the LED groups LED1 to LED4 to emit light, the light emission voltage V3 of the LED group LED3 is defined as a voltage to drive the LED groups LED1 to LED3 to emit light, the light emission voltage V2 of the LED group LED2 is defined as a voltage to drive the LED groups LED1 and LED2 to emit light, and the light emission voltage V1 of the LED group LED1 is defined as a voltage to drive only the LED group LED1 to emit light.

[0031] The control unit 14 may use a current sensor voltage detected by the current sensor resistor Rs, and the current sensor voltage may be changed by the current intensity on the current path, which changes according to the light emission states of the respective LED groups of the lamp 10. The current flowing through the current sensor resistor Rs may comprise a constant current.

[0032] The control unit 14 includes a plurality of switching circuits 31 to 34 and a reference voltage control unit 20. The plurality of switching circuits 31 to 34 provide a current path for the LED groups LED1 to LED4, and the reference voltage control unit 20 provides reference voltages VREF1 to VREF4.

[0033] The reference voltage control unit 20 includes a plurality of resistors R1 to R5 connected in series to receive a constant voltage VREF. The reference voltage control unit 20 may include a plurality of voltage sources to provide the reference voltages VREF1 to VREF4.

[0034] In the reference voltage control unit 20, resistor R1 is connected to ground, and resistor R5 receives the constant voltage VREF. Resistor R5 serves as a load resistor for adjusting an output. Resistors R1 to R4 output reference voltages VREF1 to VREF4, which have different levels. Among the reference voltages VREF1 to VREF4, reference voltage VREF1 can have the lowest voltage level, and reference voltage VREF4 can have the highest voltage level.

[0035] The AC resistors R1 to R4 may be configured to output four reference voltages VREF1 to VREF4 whose levels progressively increase in response to changes in the rectified voltage applied to the LED groups LED1 to LED4.

[0036] The reference voltage VREF1 has a level to turn off the switching circuit 31 at the time when the LED group LED2 emits light.

[0037] More specifically, the reference voltage VREF1 can be set to a level equal to or lower than the current sensing voltage formed in the current sensing resistor Rs by the light emission voltage of the LED group LED2.

[0038] The reference voltage VREF2 has a level to turn off the switching circuit 32 at the time the LED group LED3 emits light. More specifically, the reference voltage VREF2 can be set to a level equal to or lower than the current sensing voltage generated in the current sensing resistor Rs by the light emission voltage of the LED group LED3.

[0039] The reference voltage VREF3 has a level sufficient to turn off the switching circuit 33 at the time the LED group LED4 emits light. Specifically, the reference voltage VREF3 can be set to a level equal to or lower than the current sensing voltage generated in the current sensing resistor Rs by the light emission voltage of the LED group LED4.

[0040] The reference voltage VREF4 can be set to a higher level than the current sensor voltage formed in the current sensor resistor Rs by the upper limit level of the rectified voltage.

[0041] The switching circuits 31 to 34 are commonly connected to the current sensing resistor Rs to provide the current sensing voltage.

[0042] The switching circuits 31 to 34 compare the current sensing voltage of the current sensing resistor Rs with the reference voltages VREF1 to VREF4 of the reference voltage control unit 20 and are turned on / off to provide a selective current path for controlling the lamp 10 to emit light.

[0043] Each of the switching circuits 31 to 34 receives a high-level reference voltage, the switching circuit being connected to an LED group remote from the position to which the rectified voltage is applied.

[0044] Each of the switching circuits 31 to 34 may include a comparator 50 and a switching element, and the switching element may include an NMOS transistor 52.

[0045] The comparator 50 included in each of the switching circuits 31 to 34 includes a positive input terminal (+) configured to receive a reference voltage, a negative input terminal (-) configured to receive a current sensor voltage, and an output terminal configured to output a result obtained by comparing the reference voltage with the current sensor voltage. The NMOS transistor 52 included in each of the switching circuits 31 to 34 is turned on or off to selectively provide a current path according to the output of the comparator 50 applied to its gate electrode.

[0046] According to the configuration described above, the control circuit according to the embodiment in Fig. 1 a function for the light emission by the lamp. This function is described with reference to Fig. 2 described.

[0047] When the rectified voltage is in its initial state, the LED groups are off. Thus, the current sensing resistor Rs provides a low-level current sensing voltage.

[0048] More specifically, when the rectified voltage is in the initial state, all the switching circuits 31 to 34 maintain the on state because the reference voltages VREF1 to VREF4 applied to the positive input terminals (+) of the respective switching circuits 31 to 34 are higher than the current sensor voltage applied to the negative input terminals (-).

[0049] Subsequently, when the rectified voltage rises and reaches the light emission voltage V1, the LED group LED1 of the lamp 10 emits light. When the LED group LED1 of the lamp 10 emits light, the switching circuit 31 of the control unit 14, which is connected to the LED group LED1, provides a current path.

[0050] When the rectified voltage reaches the light emission voltage V1, causing the LED group LED1 to emit light, the current path is formed through the switching circuit 31, and the current sensing voltage level of the current sensing resistor Rs rises. However, since the current sensing voltage is at a low level at this time, the on-states of the switching circuits 31 to 34 are not changed.

[0051] Subsequently, as the rectified voltage progressively increases and reaches the light-emitting voltage V2, the LED group LED2 of the lamp 10 emits light. When the LED group LED2 of the lamp 10 emits light, the switching circuit 32 of the control unit 14, which is connected to the LED group LED2, provides a current path. At this time, the LED group LED1 also maintains the light-emitting state.

[0052] When the rectified voltage reaches the light emission voltage V2, so that the LED group LED2 is turned on, a current path is formed through the switching circuit 32, and the current sensing voltage level of the current sensing resistor Rs rises. At this time, the current sensing voltage has a higher level than the reference voltage VREF1. Therefore, the NMOS transistor 52 of the switching circuit 31 is turned off by the output of the comparator 50. This means that the switching circuit 31 is turned off, and the switching circuit 32 provides a current path corresponding to the light emission of the LED group LED2.

[0053] Subsequently, as the rectified voltage progressively increases and reaches the light-emitting voltage V3, the LED group LED3 of the lamp 10 emits light. When the LED group LED3 of the lamp 10 emits light, the switching circuit 33 of the control unit 14, which is connected to the LED group LED3, provides a current path. At this time, the LED groups LED1 and LED2 also maintain the light-emitting state.

[0054] When the rectified voltage reaches the light emission voltage V3, causing the LED group LED3 to emit light, a current path is formed through the switching circuit 33, and the current sensing voltage level of the current sensing resistor Rs rises. At this time, the current sensing voltage is higher than the reference voltage VREF2. Therefore, the NMOS transistor 52 of the switching circuit 32 is turned off by the output of the comparator 50. This means that the switching circuit 32 is turned off, and the switching circuit 33 provides a current path corresponding to turning on the LED group LED3.

[0055] Subsequently, as the rectified voltage progressively increases and reaches the light-emitting voltage V4, the LED group LED4 of the lamp 10 emits light. When the LED group LED4 of the lamp 10 emits light, the switching circuit 34 of the control unit 14, which is connected to the LED group LED4, provides a current path. At this time, the LED groups LED1 to LED3 also maintain the light-emitting state.

[0056] When the rectified voltage reaches the light emission voltage V4, causing the LED group LED4 to emit light, a current path is formed through the switching circuit 34, and the current sensing voltage level of the current sensing resistor Rs rises. At this time, the current sensing voltage is higher than the reference voltage VREF3. Therefore, the NMOS transistor 52 of the switching circuit 33 is turned off by the output of the comparator 50. This means that the switching circuit 33 is turned off, and the switching circuit 34 provides a current path corresponding to the light emission of the LED group LED2.

[0057] Although the rectified voltage progressively increases, the switching circuit 34 subsequently maintains the on-state because the reference voltage VREF4 applied to the switching circuit 34 has a higher level than the current sensor voltage formed in the current sensor resistor Rs by the upper limit level of the rectified voltage.

[0058] The rectified voltage begins to decrease after the upper limit level.

[0059] When the rectified voltage drops below the light emission voltage V4, the LED group LED4 of the lamp 10 is switched off.

[0060] When the LED group LED4 of the lamp 10 is turned off, the LED groups LED3, LED2 and LED1 maintain the light-emitting state and the control unit 14 provides a current path through the switching circuit 33 in response to the light-emitting state of the LED group LED3.

[0061] If the rectified voltage then progressively drops below the light emission voltages V3, V2 and V1, the LED groups LED3, LED2 and LED1 of the lamp 10 are switched off successively.

[0062] When the LED groups LED3, LED2 and LED1 of the lamp 10 are successively turned off, the control unit 14 successively provides a current path to the switching circuits 33, 32 and 31, shifting the current path.

[0063] As described above, the LED groups LED1 to LED4 of the lamp 10 can be sequentially turned on and off according to the rectified voltage, and the control unit 14 can selectively provide a current path for light emission by current control.

[0064] Due to an environmental factor of the power supply in a building, region or country or a temporarily unstable environmental factor of the power supply, a non-uniform voltage may be supplied to the lamp 10. In this case, if an AC voltage supply VAC has fluctuations, an inrush current ILED, which is as in Fig. 2 is supplied to the lamp 10, may be variable and thus destabilise the power supplied to the lamp 10.

[0065] The LED lighting device according to the embodiment in Fig. 1 may include a rectified voltage compensation circuit 28 and a rectified voltage sensor unit 16 for providing a sensor signal obtained by detecting the rectified voltage, thereby ensuring uniform brightness by compensating for fluctuations in the voltage supplied to the lamp 10 that occur due to the unstable AC voltage source VAC.

[0066] The rectified voltage sensor unit 16 may be configured to output a sensor signal obtained by dividing the rectified voltage by series-connected resistors Ra and Rb. The rectified voltage sensor unit 16 configured as described above may receive a rectified voltage having the same frequency and waveform as the rectified voltage supplied to the lamp 10, as shown in Fig. 3A is shown.

[0067] The rectified voltage sensor unit 16 generates and outputs a sensor signal obtained by scaling down the rectified voltage according to the resistance ratio of the resistors Ra and Rb, as shown in Fig. 3B is shown.

[0068] The control unit 14 includes the rectified voltage compensation circuit 28 for changing the reference voltages VREF1 and VREF4 output by the reference voltage control unit 20 using the sensor signal from the rectified voltage sensor unit 16. The rectified voltage compensation circuit 28 includes a voltage sensor unit 40 and a compensation circuit 42. The rectified voltage compensation circuit 28 may be included in the control unit 14 or provided separately from the control unit 14.

[0069] The rectified voltage compensation circuit 28 generates a compensation signal for varying the reference voltages VREF1 to VREF4 output by the reference voltage control unit 20 using the sensor signal from the rectified voltage sensor unit 16. The compensation signal is supplied to the reference voltage control unit 20, and the reference voltage control unit 20 varies the levels of the reference voltages VREF1 and VREF4 according to the compensation signal. This allows the magnitude of the current flowing through the current path to be controlled to provide a constant supply to the lamp 10. This means that the rectified voltage compensation circuit 28 compensates for fluctuations in the voltage supplied to the lamp 10 due to an unstable rectified voltage caused by an environmental factor.

[0070] As a reminder, power can be expressed as the product of current and voltage. Thus, a fluctuation in the power supplied to lamp 10 can be compensated for by controlling the current path to adjust the current intensity of lamp 10. Thus, the power supplied to the light emission of lamp 10 can be maintained at a constant level. This allows the brightness of lamp 10 to be maintained constant.

[0071] The rectified voltage compensation function according to the embodiment of the present invention will now be described with reference to the operation of the voltage sensor unit 40 and the compensation circuit 42.

[0072] First, the voltage sensor unit 40 outputs a voltage sensor signal obtained by detecting the peak of the sensor signal output from the rectified voltage sensor unit 16 as shown in Fig. 3C, and the voltage sensor signal represents fluctuations in the rectified voltage depending on a power supply environmental factor in a building, region, or country, or a temporarily unstable power supply environmental factor.

[0073] The voltage sensor unit 40 supplies the above-described voltage sensor signal to the compensation circuit 42, and the compensation circuit 42 supplies a compensation signal corresponding to the voltage sensor signal to the reference voltage control unit 20. The reference voltage control unit 20 changes the reference voltages VREF1 to VREF4 for the associated LED groups depending on the compensation signal, as shown in Fig. 4 is shown.

[0074] The compensation signal can be set to a level inversely proportional to the fluctuation of the rectified voltage. Furthermore, the compensation signal can hold the reference level, and the level of the compensation signal can be lowered or raised depending on the rise or fall of the rectified voltage.

[0075] More precisely, the compensation circuit 42 outputs Fig. 1, the compensation signal is applied to the node that outputs the highest reference voltage among the nodes between the individual resistors of the reference voltage control unit 20. This means that the compensation signal can be output as a DC voltage and applied to the node between resistors R5 and R4 of the reference voltage control unit 20, which outputs the reference voltage VREF4.

[0076] When the compensation signal is applied to the node that outputs the highest reference voltage among the nodes between the individual resistors of the reference voltage control unit 20, the compensation signal can be continuously converted to the reference voltages VREF1 to VREF4 according to the resistance ratio of the respective resistors R4, R3, R2 and R1.

[0077] For example, when the rectified voltage drops, the compensation circuit 42 provides a compensation signal to the reference voltage control unit 20 having a level inversely proportional to the decreased rectified voltage.

[0078] The reference voltage control unit 20 applies the reference voltages VREF1 to VREF4, boosted by the compensation signal, to the positive terminals (+) of the associated comparator 50 of the switching circuits 31 to 34.

[0079] When the voltage level of the positive terminal (+) is raised, the comparator 50 can apply the raised voltage to the gate electrode of the NMOS transistor 52. The current driving capability of the NMOS transistor 52 is improved, and the magnitude of the current flowing through the current path formed by the NMOS transistor 52 of the switching circuits 31 to 34 is increased depending on the light emission of the corresponding LED groups LED1 to LED4 of the lamp 10.

[0080] The increase in the current flowing through NMOS transistor 52 indicates the increase in the current supplied to lamp 10. Thus, the power supplied to lamp 10 can be kept constant in response to the compensation signal, and the brightness of lamp 10 can also be kept constant.

[0081] On the other hand, even if the rectified voltage is boosted, the compensation circuit 42 supplies a compensation signal having a level inversely proportional to the boosted rectified voltage to the reference voltage control unit 20.

[0082] The reference voltage control unit 20 applies the reduced reference voltages VREF1 to VREF4 to the positive terminals (+) of the corresponding comparators 50 of the switching circuits 31 to 34.

[0083] When the voltage level of the positive terminal (+) is lowered, the comparator 50 can apply the lowered voltage to the gate electrode of the NMOS transistor 52. This reduces the current driving capability of the NMOS transistor 52, and the magnitude of the current flowing through the current path formed by the NMOS transistor 52 of the switching circuits 31 to 34 is reduced depending on the light emission of the corresponding LED groups LED1 to LED4 of the lamp 10.

[0084] The reduction in the magnitude of the current flowing through the NMOS transistor 52 indicates the reduction in the magnitude of the current supplied to the lamp 10. Thus, the power supplied to the lamp 10 can be kept constant in response to the compensation signal, and the brightness of the lamp 10 can also be kept constant.

[0085] This means that although the voltage supplied to the lamp 10 fluctuates around the reference point due to an environmental factor, as shown in Fig. 5, the power can be kept constant by the compensation signal described above and the brightness of the lamp 10 can also be kept constant.

[0086] The embodiment of the present invention can be applied to the case where the power supplied to the lamp 10 is linearly changed according to the changes in the AC voltage VAC.

[0087] However, the power supplied to the lamp 10 can be changed, having a waveform, for example a quadratic functional form, according to the change in the alternating voltage VAC.

[0088] Fig. 6 is a graph illustrating that the power supplied to the lamp 10 is varied depending on the change in the AC voltage VAC due to the power supply environment, having the curve shape described above.

[0089] In the present embodiment, the power change range (or the rectified voltage change range) may be divided into five power change sections C1 to C5 to compensate for the power supplied to the lamp 10, which is changed to have a waveform depending on the change in the AC voltage VAC, and a loop gain for compensating for the power change is applied differently to each of the divided sections. Fig. 6 shows that the power variation range is divided into five sections C1 to C5, but the number of power variation sections can be set to different values ​​according to a designer's requirements.

[0090] In the present invention, the compensation circuit 42 may be configured to have five compensation units 100, 102, 104, 106 and 108 corresponding to the five power changing sections, as shown in Fig. 7. This means that the compensation units 100, 102, 104, 106, and 108 of the compensation circuit 42, to which the voltage compensation signal output from the voltage sensor unit 40 is commonly applied, may be implemented in parallel with each other, and the compensation signals output from the compensation units 100, 102, 104, 106, and 108 may be input to the reference voltage control unit 20.

[0091] The compensation unit 100 has a loop gain for compensating the power change according to section C1, the compensation unit 102 has a loop gain for compensating the power change according to section C2, the compensation unit 104 has a loop gain for compensating the power change according to section C3, the compensation unit 106 has a loop gain for compensating the power change according to section C4 and the compensation unit 108 has a loop gain for compensating the power change according to section C5.

[0092] For the compensation units 100, 102, 104, 106, and 108 described above, the highest loop gain can be set for the compensation unit corresponding to the highest power, and the lowest loop gain can be set for the compensation unit corresponding to the lowest power. This means that the loop gains can be set according to a relationship for compensation unit 100 > compensation unit 102 > compensation unit 104 > compensation unit 106 > compensation unit 108.

[0093] In addition, the loop gains of the compensation units 100, 102, 104, 106, and 108 can be adjusted to correspond to the power changes of the corresponding sections C1 to C5. As shown in Fig. 6, the power supplied to the lamp 10 can be changed, having a waveform depending on the change in the AC voltage VAC. Furthermore, the power supplied to the lamp 10 can be changed, having a waveform within the sections C1 to C5. Thus, the compensation units 100, 102, 104, 106, and 108 can be set to have typical values ​​adapted to represent the changes in the corresponding sections C1 to C5. For example, a value obtained by differentiating the change of a section can be set to a loop gain, or a value obtained by correcting the value obtained by differentiating the change of the section can be set to a loop gain for deviation adjustment.

[0094] As described above, the compensation circuit 42 includes the compensation units 100, 102, 104, 106, and 108, which have different loop gains. Each of the compensation units 100, 102, 104, 106, and 108 outputs a compensation signal to which its loop gain is applied when the voltage sensor signal output by the voltage sensor unit 40 is assigned to the compensation unit. This means that the compensation circuit 42 can output a compensation signal to which a different loop gain is applied in each of the sections C1 to C5, depending on the amount of power supplied to the lamp 10 in accordance with the change in the AC voltage VAC.

[0095] This means that the compensation circuit 42 can output the compensation signal, to which a different loop gain is applied in each of the sections C1 to C5, to the node that outputs the highest reference voltage among the nodes between the individual resistors of the reference voltage control unit 20, depending on the amount of power supplied to the lamp 10 in accordance with the change in the AC voltage VAC. Thus, the reference voltage control unit 20 provides the reference voltages VREF1 to VREF4 in which the compensation signal is implemented.

[0096] As described above, the reference voltages VREF1 to VREF4, which implement the change in the power supplied to the lamp 10, can be applied to the positive terminals (+) of the corresponding comparators 50 of the switching circuits 31 to 34.

[0097] This allows the current driving capability of NMOS transistor 52 to be varied according to changes in the power supplied to lamp 10. Thus, the current supplied to lamp 10 can be adjusted.

[0098] Therefore, the control circuit according to the embodiment of the Fig. 6 and Fig. 7 control the reference voltages using the compensation signal, to which a different loop gain is applied in each of the sections C1 to C5, depending on the amount of power supplied to the lamp 10 in accordance with the change in the AC voltage VAC. Thus, the current supplied to the lamp 10 can be adjusted so that the power supplied to the lamp 10 is kept constant, and the brightness of the lamp 10 can be kept constant.

[0099] Although various embodiments have been described above, it will be apparent to those skilled in the art that the described embodiments are only exemplary. Therefore, the disclosure described in this document should not be limited by the described embodiments.

Claims

[1] Control circuit for an LED lighting device comprising a plurality of LED groups (LED1-LED4) for emitting light in accordance with a rectified voltage, the control circuit comprising: a rectified voltage sensor unit (16) configured to detect the rectified voltage and provide a sensor signal; and a control unit (14) configured to compare reference voltages (VREF1-VREF4) with a current sensor voltage corresponding to a current intensity based on the light emission of the LED groups (LED1-LED4), wherein the reference voltages (VREF1-VREF4) are associated with the respective LED groups (LED1-LED4) and have different levels that are set depending on the sensor signal, and to provide a current path associated with the light emission states of the LED groups (LED1-LED4), wherein the levels of the reference voltages (VREF1-VREF4) are set to be inversely proportional to the rectified voltage, thereby ensuring uniform brightness by compensating for voltage fluctuations, and where the current strength on the current path is controlled depending on the sensor signal. [2] The control circuit according to claim 1, wherein the rectified voltage sensor unit (16) outputs a signal obtained by scaling down the rectified voltage as the sensor signal. [3] Control circuit according to claim 1, wherein the control unit (14) comprises: a rectified voltage compensation circuit (28) configured to generate a compensation signal corresponding to changes in the power supplied to the plurality of LED groups (LED1-LED4) in response to the sensor signal; a reference voltage control unit (20) configured to provide the reference voltages (VREF1-VREF4) into which the compensation signal is converted; and a plurality of switching circuits (31-34) provided for the respective LED groups (LED1-LED4) and configured to compare the reference voltages (VREF1-VREF4) associated with the respective LED groups (LED1-LED4) with the current sensor voltage corresponding to the current intensity on the current path, and to provide the current path corresponding to the light emission states of the LED groups (LED1-LED4). [4] A control circuit according to claim 3, wherein the rectified voltage compensation circuit (28) generates the compensation signal at a level inversely proportional to fluctuations in the rectified voltage. [5] A control circuit according to claim 3, wherein the power variation range is divided into a plurality of sections and the rectified voltage compensation circuit (28) generates the compensation signal by applying a different loop gain in each of the sections. [6] A control circuit according to claim 3, wherein the rectified voltage compensation circuit (28) comprises: a voltage sensor unit (40) configured to detect the peak of the rectified voltage using the sensor signal and to provide a voltage sensor signal corresponding to the peak; and a compensation circuit (42) configured to generate the compensation signal depending on the level of the voltage sensor signal corresponding to the change in power supplied to the plurality of LED groups (LED1-LED4). [7] A control circuit according to claim 3, wherein the rectified voltage compensation circuit (28) comprises: a voltage sensor unit (40) configured to detect the peak of the rectified voltage using the sensor signal and to provide a voltage sensor signal corresponding to the peak; and a compensation circuit (42) configured to divide the change in power into a plurality of sections and to generate the compensation signal corresponding to the change in power supplied to the plurality of LED groups (LED1-LED4) by applying a different loop gain in each of the sections. [8] The control circuit according to claim 7, wherein the compensation circuit (42) comprises a plurality of compensation units (100-108), each of which has the loop gain corresponding to the section and is adapted to output the compensation signal corresponding to the loop gain. [9] The control circuit of claim 1, wherein the control unit (14) decreases the current on the current path when the rectified voltage increases and increases the current on the current path when the rectified voltage decreases. [10] A control circuit according to claim 9, wherein the control unit divides the power variation of the power into a plurality of spans and controls the current by applying a different loop gain in each of the sections. [11] A control circuit for an LED lighting device comprising a plurality of LED groups (LED1-LED4) for emitting light in accordance with a rectified voltage, the control circuit comprising: a rectified voltage sensor unit (16) configured to provide a sensor signal obtained by detecting the rectified voltage; a rectified voltage compensation circuit (28) configured to generate, in response to the sensor signal, a compensation signal corresponding to the change in power supplied to the plurality of LED groups (LED1-LED4); a reference voltage control unit (20) configured to convert the compensation signal and provide reference voltages (VREF1-VREF4) associated with the respective LED groups (LED1-LED4); and a plurality of switching circuits (31-34) provided for the respective LED groups (LED1-LED4) and configured to compare the reference voltages (VREF1-VREF4) with a current sensor voltage corresponding to a current intensity based on the light emission of the LED groups (LED1-LED4), and providing a current path associated with the light emission states of the LED groups (LED1-LED4), wherein the level of the reference voltages (VREF1-VREF4) is set to be inversely proportional to the rectified voltage, thereby ensuring uniform brightness by compensating for voltage fluctuations, and wherein the reference voltages (VREF1-VREF4) are controlled in dependence on changes in the power supplied to the plurality of LED groups (LED1-LED4) such that the current on the current path is controlled. [12] A control circuit according to claim 11, wherein the rectified voltage compensation circuit (28) comprises: a voltage sensor unit (40) configured to detect the peak of the rectified voltage using the sensor signal and to provide a voltage sensor signal corresponding to the peak; and a compensation circuit (42) configured to generate the compensation signal depending on the level of the voltage sensor signal corresponding to the change in power supplied to the plurality of LED groups (LED1-LED4). [13] A control circuit according to claim 11, wherein the rectified voltage compensation circuit (28) comprises: a voltage sensor unit (40) configured to detect the peak of the rectified voltage using the sensor signal and to provide a voltage sensor signal corresponding to the peak; and a compensation circuit (42) configured to divide the range of change of the rectified voltage into a plurality of sections and to generate the compensation signal in accordance with the change in the power supplied to the plurality of LED groups (LED1-LED4) by applying a different loop gain in each of the sections. [14] The control circuit according to claim 13, wherein the compensation circuit (42) comprises a plurality of compensation units (100-108), each of which has the loop gain corresponding to the section and is adapted to output the compensation signal corresponding to the loop gain. [15] The control circuit of claim 11, wherein the rectified voltage compensation circuit (28), the reference voltage control unit (20) and the plurality of switching circuits (31-34) are included in a control unit (14) implemented as a chip. [16] The control circuit of claim 11, wherein the reference voltage control unit (20) and the plurality of switching circuits (31-34) are included in a control unit (14) implemented as a chip. [17] The control circuit of claim 11, wherein the rectified voltage compensation circuit (28) generates the compensation signal to decrease the current on the current path when the rectified voltage increases and to increase the current on the current path when the rectified voltage decreases. [18] A control circuit for an LED lighting device comprising a plurality of LED groups (LED1-LED4) for emitting light in accordance with a rectified voltage, the control circuit comprising: a rectified voltage compensation circuit (28) configured to generate a compensation signal from a sensor signal provided as a function of the rectified voltage, said compensation signal corresponding to changes in the power supplied to the plurality of LED groups (LED1-LED4); and a circuit configured to provide a current path for light emission by the LED groups (LED1-LED4), which emit light in response to changes in the rectified voltage, and to control a current intensity on the current path in response to the compensation signal, wherein reference voltages (VREF1-VREF4) are assigned to the respective LED groups (LED1-LED4) and have different levels that are set depending on the sensor signal, and provide a current path assigned to the light emission states of the LED groups (LED1-LED4), wherein the level of the reference voltages (VREF1-VREF4) is set to be inversely proportional to the rectified voltage, thereby ensuring uniform brightness by compensating for voltage fluctuations, and where the current strength on the current path is controlled depending on the sensor signal. [19] A control circuit according to claim 18, wherein the rectified voltage compensation circuit (28) comprises: a voltage sensor unit (40) configured to detect the peak of the rectified voltage and to provide a voltage sensor signal corresponding to the peak; and a compensation circuit (42) configured to generate the compensation signal depending on the level of the voltage sensor signal corresponding to the change in power supplied to the plurality of LED groups (LED1-LED4). [20] A control circuit according to claim 18, wherein the circuit comprises: a reference voltage control unit (20) configured to provide the reference voltages (VREF1-VREF4) associated with the respective LED groups (LED1-LED4); and a plurality of switching circuits (31-34) provided for the respective LED groups (LED1-LED4) and configured to compare the reference voltages (VREF1-VREF4) with a current sensor voltage corresponding to the current intensity based on the light emission of the LED groups (LED1-LED4), and providing the current path associated with the light emission states of the LED groups (LED1-LED4), and wherein the reference voltages (VREF1-VREF4) are controlled depending on the compensation signal, such that the current on the current path is controlled.

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