JP6063515B2 - Low flicker light emitting diode lighting device having a plurality of driving stages - Google Patents

Description

  The present invention relates to a light emitting diode (LED) lighting device having a plurality of drive stages, and more particularly, provides a wide and efficient operating voltage range without causing flicker and uniformity problems. The present invention relates to an LED lighting device having a plurality of drive stages for providing.

  This application is one of US Provisional Patent Application No. 14 / 267,916, filed May 2, 2014, which claims the benefit of US Provisional Patent Application No. 61 / 844,438, filed July 10, 2013. Department of continuation application. This application claims the benefit of US Provisional Patent Application No. 61 / 991,627, filed May 12, 2014.

  LED lighting devices that are directly driven by a rectified alternating current (AC) voltage typically employ a plurality of LEDs connected in series to provide the required brightness. As the number of LEDs increases, a higher forward bias voltage is required to turn on the LED lighting device, thereby reducing the efficient operating voltage range of the LED lighting device. As the number of LEDs decreases, large drive currents when the rectified voltage is at its maximum level can affect the reliability of the LEDs.

  The LED lighting device is configured to adjust the luminous flux and the luminous intensity. This time change is generally called flicker. Whether or not it can be perceived, LED flicker has been a concern in the lighting industry due to the potential human impact of LED flicker, which varies from distraction, mild discomfort to nerve problems. . Therefore, there is a need for an LED lighting device that can improve the efficient operating voltage range, reliability, and flicker phenomenon.

  The present invention provides an LED lighting device having a first drive stage and a second drive stage. The first drive stage is driven by a rectified AC voltage to provide light according to a first current, and is driven by a rectified AC voltage to provide light according to a second current. A second light emitting element to be driven, connected in series to the first light emitting element, and configured to control the first current so that the first current does not exceed the first value. Current controller connected in series to the second light emitting element, the second current controller configured to control the second current so that the second current does not exceed the second value Discharging energy to the first light emitting element when coupled in parallel to at least the first light emitting element and the rectified AC voltage is insufficient to turn on the first light emitting element; So that the first light emitting device is kept turned on. A first charge storage unit formed, and a first end and a second current configured to conduct a third current and coupled between the first light emitting element and the first current controller. A path controller having a second end coupled to the controller is included. The second drive stage is coupled in series with the first drive stage to conduct the fourth current and to control the fourth current so that the fourth current does not exceed the third value. A third current controller configured as described above.

  These and other objects of the present invention will become apparent to those skilled in the art after reading the following detailed description of the preferred embodiment illustrated in the various diagrams and drawings.

1 is a diagram of an LED lighting device according to an embodiment of the present invention. 1 is a diagram of an LED lighting device according to an embodiment of the present invention. 1 is a diagram of an LED lighting device according to an embodiment of the present invention. 1 is a diagram of an LED lighting device according to an embodiment of the present invention. It is a figure which illustrates operation | movement of the several drive stage in the LED lighting device of this invention. It is a figure which illustrates operation | movement of the several drive stage in the LED lighting device of this invention. It is a figure which illustrates operation | movement of the several drive stage in the LED lighting device of this invention. It is a figure which illustrates operation | movement of the several drive stage in the LED lighting device of this invention. It is a figure which illustrates operation | movement of the several drive stage in the LED lighting device of this invention. It is a figure which illustrates the current-time characteristic of the light emitting element in the LED lighting device of this invention. It is a figure which illustrates operation | movement of the whole LED lighting device by the Example of this invention. It is a figure which illustrates operation | movement of the whole LED lighting device. It is a figure of the LED lighting device by the other Example of this invention. It is a figure of the LED lighting device by the other Example of this invention. It is a figure of the LED lighting device by the other Example of this invention. It is a figure of the LED lighting device by the other Example of this invention.

1 to 4 are diagrams of LED lighting devices 101 to 104 according to an embodiment of the present invention. Each of the LED lighting devices 101 to 104 includes a power supply circuit 110 and (N + 1) drive stages ST _{1 to} ST _{N + 1} . The power supply circuit 110 receives an AC voltage VS having positive and negative periods to drive (N + 1) drive stages, and converts the output of the AC voltage VS in the negative period using the bridge rectifier 112. , and thereby to provide a rectified AC voltage V _AC values change periodically with time. In another embodiment, the power supply circuit 110 receives any AC voltage VS, performs voltage conversion using an AC-AC converter, and rectifies the converted AC voltage VS using a bridge rectifier 112, which _Can provide a rectified AC voltage VAC whose value changes periodically with time. The configuration of the power supply circuit 110 does not limit the scope of the present invention.

In the LED lighting devices 101 to 103, each of the first to Nth drive stages ST _{1 to} ST _N includes a plurality of light emitting elements, a path controller, a first type current controller, and a second type current control. wherein vessels, and the M charge storage unit _CH 1 to CH _M, where, N is a positive integer greater than one, M is a positive integer equal to 2N less than or 2N. The (N + 1) th drive stage ST _{N + 1} includes a third type of current controller.

In the LED lighting device 104, the first driving stage ST ₁ includes a plurality of light emitting elements, while each of the second N-th driving stage _ST 2 ～ST _N, a plurality of light emitting elements, the route controller, Including a first type of current controller, a second type of current controller, and M charge storage units CH _{1 to} CH _M , where N is a positive integer greater than 1 and M is 2N A positive integer less than or equal to 2N. The (N + 1) th drive stage ST _{N + 1} includes a third type of current controller.

  Each first type of current controller includes an adjustable current source and a current detection and control unit. Each second type of current controller includes an adjustable current source and a voltage detection and control unit. A third type of current controller includes an adjustable current source and a detection and control unit.

For illustrative purposes, the following symbols are used throughout the specification and drawings to represent each element in the LED lighting devices 101-104. A ₁ to A _N and _B 1 .about.B _N each represent a light emitting element in the corresponding driving stage _ST 1 _{~ST N.} D ₁ to D _N, respectively, representative of the path controller in the corresponding driving stage _ST 1 _{~ST N.} CCA ₁ ~CCA _N, respectively, represent a first type of the current controller in a corresponding driving stage _ST 1 _{~ST N.} CCB ₁ ~CCB _N, respectively, represent a second type of the current controller in a corresponding driving stage _ST 1 _{~ST N.} CC _{N + 1} represents a third type of current controller in the (N + 1) th drive stage ST _{N + 1} . ISA ₁ ~ISA _N each represent an adjustable current source in the corresponding first type of the current controller _CCA 1 _{~CCA N.} ISB ₁ ~ISB _N each represent an adjustable current source in the corresponding second kind of the current controller _CCB 1 _{~CCB N.} IS _{N + 1} represents an adjustable current source in the third type of current controller CC _{N + 1} . UNA ₁ ~UNA _N each represent a current sensing and control unit in the corresponding first type of the current controller _CCA 1 _{~CCA N.} UNB ₁ ~UNB _N, respectively, representing the voltage detection and control unit in the corresponding second kind of the current controller _CCB 1 _{~CCB N.} UN _{N + 1} represents the detection and control unit in the (N + 1) th drive stage ST _{N + 1} .

For illustrative purposes, the following symbols are used throughout the specification and drawings to represent the associated current / voltage in LED lighting devices 101-104. V _IN1 ~V _INN, respectively, representing the voltage established across the N-th driving stage _ST 1 ～ST _N from the first. V _{AK1 to} V _AKN represent voltages established across the corresponding first type current controllers CCA _{1 to} CCAN _N , respectively. V _{BK1 to} V _BKN represent voltages established across the corresponding second type current controllers CCB _{1 to} CCB _N , respectively. V _CK represents the voltage established across the third type of current controller CC _{N + 1} . I _{AK1 to} I _AKN represent currents flowing through the corresponding first type current controllers CCA _{1 to} CCAN _N , respectively. I _BK1 ~I _BKN, respectively, representative of the current flowing through the corresponding second kind of the current controller _CCB 1 _{~CCB N.} I _A1 ~I _AN, respectively, representative of the current flowing through the corresponding light emitting element _A 1 to A _N. I _{B1 to} I _BN represent currents flowing through the corresponding light emitting elements B _{1 to} B _N , respectively. I _D1 ~I _DN, respectively, representative of the current flowing through the corresponding routing controller _D 1 to D _N. I _SUM1 ~I _SUMN, respectively, representative of the current flowing through the corresponding drive stage _ST 1 _{~ST N.} The total current of the LED lighting devices 101-104 can be represented by _{ISUM (N + 1)} .

From the first LED lighting device 101 to 103 in N-th driving stage _ST 1 _{~ST N,} are connected in series to the corresponding light-emitting element _A 1 to A _N and the corresponding adjustable current source _ISA 1 ～ISA _N that the current detection and control unit _UNA 1 _{~UNA N,} respectively, currents _I AK1 _{~I AKN} control the value of the adjustable current source _ISA 1 _{~ISA N} according (Regulate: adjustment) configured to. Series to the light emitting element _B 1 .about.B _N respectively corresponding and the corresponding adjustable current source _ISB 1 voltage detection and control unit is connected in parallel to the ~ISB _{N UNB} 1 ~UNB _N, respectively, the voltage _{V BK1} configured to control the value of the adjustable current source _ISB 1 _{~ISB N} according ~V _BKN.

From the second LED lighting device 104 in the N-th driving stage _ST 2 _{~ST N,} the corresponding light-emitting element _A 2 to A _N and the corresponding adjustable current source _ISA 2 ～ISA _N to the current connected in series detection and control unit _UNA 2 _{~UNA N} are each configured to control the value of the adjustable current source _ISA 2 _{~ISA N} as the current _I AK2 _{~I AKN.} Series to the light-emitting element _B 2 .about.B _N respectively corresponding and the corresponding adjustable current source _ISB 2 voltage detection and control unit is connected in parallel to the ~ISB _{N UNB} 2 ~UNB _N, respectively, the voltage _{V BK2} configured to control the value of the adjustable current source _ISB 2 _{~ISB N} according ~V _BKN.

In the (N + 1) th drive stage ST _{N + 1} of the LED lighting devices 101 to 104, the adjustable current source IS _{N + 1} is connected in series to the _{first to} Nth drive stages ST _{1 to} ST _N. In the first configuration, the detection and control unit UN _{N + 1} of the third type of current controller CC _{N + 1} can be connected in series to the adjustable current source IS _{N + 1} and can be adjusted according to the current I _{SUMN. It} is configured to control the value of _{N + 1} . In the second configuration, the detection and control unit UN _{N + 1} of the third type of current controller CC _{N + 1} can be connected in parallel to the adjustable current source IS _{N + 1} and adjustable according to the voltage V _{CK It} is configured to control the value of _{N + 1} . 1-4 depict an embodiment employing the first configuration, but does not limit the scope of the invention.

In the embodiment of the present invention, each of the light emitting elements A _{1 to} A _N and B _{1 to} B _N may employ a single LED or a plurality of LEDs connected in series. 1-4 include single-junction LEDs, multi-junction high-voltage (HV) LEDs, or any combination of various types of LEDs. An example using multiple resulting LEDs is depicted. However, the types and configurations of the light emitting elements A _{1 to} A _N and B _{1 to} B _N do not limit the scope of the present invention. In a specific driving stage, a drop-out voltage V _{DROP for} turning on a corresponding current controller is lower than a cut-in voltage V _{CUT for} turning on a corresponding light emitting device. small. A particular light emitting element can be placed in a conducting on state when the voltage established across the particular light emitting element exceeds the light emitting element cut-in voltage V _CUT . If the voltage established across a particular light emitting element does not exceed the light emitting element's cut-in voltage V _CUT , the particular light emitting element may be placed in a non-conductive off state. The value of the cut-in voltage V _CUT is related to the number or type of LEDs in the corresponding light emitting element and can vary in different applications.

In an embodiment of the present invention, each of the M charge storage units CH _{1 to} CH _M may employ a capacitor or one or more elements that provide a similar function. However, the types and configurations of the charge storage units CH _{1 to} CH _M do not limit the scope of the present invention.

In an embodiment of the present invention, each of the path controllers D _{1 to DN} may be a diode, a diode-connected field effect transistor (FET), a diode-connected bipolar junction transistor (BJT), or other element having a similar function, or One or more elements that provide similar functions may be employed. However, the types and configurations of the path controllers D _{1 to DN} do not limit the scope of the present invention. When the voltage established across a particular path controller exceeds the turn-on voltage of the path controller, the particular path controller is forward biased and short circuited (short -When a voltage established across a particular routing controller does not exceed the turn-on voltage of the routing controller, the particular routing controller is reverse biased and opened Functions as an open-circuited device.

5 to 8 are diagrams illustrating the operation of the first in the LED lighting device 101 to 103 according to an embodiment N-th driving stage _ST 1 ～ST _N of the present invention. Drive stage ST ₁ in the LED lighting device 101 to 103 is used for illustrative purposes, here, FIG. 5, a first type of the current controller CCA ₁ current - voltage curve (I-V curve 6 illustrates the IV curve of the second type of current controller CCB ₁ and FIG. 7 illustrates the equivalent circuit of the _first drive stage ST ₁ during different stages of operation. FIG. 8 illustrates the IV curve of the _first drive stage ST1, and FIG. 9 illustrates the current controller CC _{N + 1 in} the (N + 1) th drive stage ST _{N + 1} of the LED lighting devices 101 to 104. It is a figure which illustrates operation | movement. V _DROPA , V _DROPB , and V _DROPC are used to _turn on the first type current controller CCA ₁ , the second type current controller CCB ₁ , and the third type current controller CC _{N + 1} , respectively. Represents dropout voltage. V _OFFA , V _OFFB , and V _ONB represent threshold voltages, and the first type current controller CCA ₁ or the second type current controller CCB ₁ operates based on the threshold voltage. Switch. I _SETA1 , I _SETB1 , and I _SETC are current setting values of the first type current controller CCA ₁ , the second type current controller CCB ₁ , and the third type current controller CC _{N + 1} , respectively. Is a fixed value representing An arrow R indicates a rising period of the voltage V _AK1 , the voltage V _BK1 , or the voltage V _CK . An arrow F indicates a falling period of the voltage V _AK1 , the voltage V _BK1 , or the voltage V _CK .

In FIG. 5, during the rising and falling periods of the voltage V _AK1 when 0 <V _AK1 <V _DROPA , the first type current controller CCA ₁ is not fully turned on and the current I _AK1 is It operates as a voltage-controlled element in a linear mode that varies in a specific way with the voltage V _AK1 . For example, if the first type of current controller CCA ₁ is implemented using a metal oxide semiconductor (MOS) transistor, the relationship between the current I _AK1 and the voltage V _AK1 operates in the linear region. It can correspond to the IV characteristic of the MOS transistor when

During the rising and falling periods of the voltage V _AK1 when V _AK1 > V _DROPA , the current I _AK1 reaches I _SETA1 and the first type of current controller CCA ₁ switches to constant current mode, Functions as a current limiter. The current detection and control unit UNA ₁ is configured to clamp the current I _AK1 to I _SETA1 . For example, in response to an increase in the current I _D1 , the current detection and control unit UNA ₁ can consequently decrease the value of the adjustable current source ISA ₁ . Similarly, in response to a decrease in current I _D1, the current sensing and control unit UNA ₁ may result, increase the adjustable value of the current source ISA _1. Therefore, the current I _AK1 (= I _D1 + ISA ₁ ) flowing through the _first drive stage ST ₁ can be maintained at a fixed value I _SETA1 instead of changing with the voltage V _AK1 .

During the rising period of the voltage V _AK1 before the current I _D1 reaches I _SETA1 , the current detection and control unit UNA ₁ turns on the adjustable current source ISA ₁ and the first type of current controller CCA. ₁ functions as a current limiter in a constant current mode in which the current I _AK1 (= I _SETA1 + I _D1 ) is clamped at a fixed value of I _SETA1 . When the current I _D1 reaches I _SETA1 , the current detection and control unit UNA ₁ turns off the adjustable current source ISA ₁ and the first type of current controller CCA ₁ has a current I _{AK1 Switch} to cut-off mode, increasing with _ID1 .

During the falling period of the voltage V _AK1 before the current I _D1 decreases to I _SETA1 , the current detection and control unit UNA ₁ turns off the adjustable current source ISA ₁ and the first type of current controller CCA. ₁ operates in a cut-off mode where the current I _AK1 decreases with the current I _D1 . When the current I _D1 decreases to I _SETA1 , the current detection and control unit UNA ₁ turns on the adjustable current source ISA ₁ and the first type of current controller CCA ₁ has a current I _AK1 of I _It functions as a current limiter in the constant current mode clamped at a fixed value of _SETA1 .

In FIG. 6, during the rising and falling periods of the voltage V _BK1 when 0 <V _BK1 <V _DROPB , the second type current controller CCB ₁ is not fully turned on and the current I _BK1 is It operates as a voltage controlled element in a linear mode that varies in a specific manner with the voltage V _BK1 . For example, if the second type of current controller CCB ₁ is implemented using MOS transistors, the relationship between current I _BK1 and voltage V _BK1 is the MOS transistor when operating in the linear region. It is possible to correspond to the IV characteristics.

During the rising period of the voltage V _BK1 when V _BK1 > V _DROPB , the current I _BK1 reaches I _SETB1 and the second type of current controller CCB ₁ switches to the constant current mode, and the current limiter Function as. The voltage detection and control unit UNB ₁ is configured to clamp the current I _BK1 to I _SETB1 .

During the rising period of the voltage V _BK1 when V _BK1 > V _OFFB , the voltage detection and control unit UNB ₁ is configured to turn off the adjustable current source ISB ₁ and the second type of current The controller CCB ₁ switches to the cut-off mode. In other words, the second type of current controller CCB ₁ functions as an open element. During the falling period of the voltage V _BK1 when V _BK1 <V _ONB , the voltage detection and control unit UNB ₁ is configured to turn on the adjustable current source ISB ₁ and the second type of current Controller CCB ₁ switches to constant current mode and functions as a current limiter, thereby clamping current I _BK1 to I _SETB1 . Threshold voltage _{V ONB} is equal to the threshold voltage _{V OFFB,} or larger than the threshold voltage _{V OFFB.} In an embodiment, a non-zero hysteresis width (V _ONB −V _OFFB ) is provided to prevent the second type current controller CCB ₁ from frequently switching operating modes due to variations in the voltage V _BK1 . obtain.

7, when the first driving stage ST ₁ is operated in a first step is _{V1 <V} IN1 _<V2, as depicted in the left side of FIG. 7, the light-emitting element _{A 1} is the light-emitting element _{B 1} Connected in parallel. When the first driving stage ST ₁ operates in the second stage where V _IN1 > V3, the light emitting element A ₁ is connected in series to the light emitting element B ₁ as depicted on the right side of FIG. .

In FIG. 8, the light emitting element A ₁ , the light emitting element B ₁ , and the path controller D ₁ are kept off during the rising period when the voltage V _IN1 is low. Voltage V _IN1, increasing period to reach the turn-on voltage V _A1 is the sum of the cut-in voltage for turning on the current controller CCA _first cut-in voltage and the first type of order to turn on the light-emitting element A _{1 Meanwhile} , the first type current controller CCA ₁ and the light emitting element A ₁ are turned on, _allowing the current I _A1 to gradually increase with the voltage V _IN1 until it reaches I _SETA1 , and the voltage V _IN1 is During the rising period to reach the turn-on voltage V _B1 , which is the sum of the cut-in voltage for turning on the light emitting element B ₁ and the cut-in voltage for turning on the second type current controller CCB ₁ , types of current controller CCB ₁ and the light-emitting element _{B 1} represents is turned on, a current _{I B1 is,} with the voltage _{V IN1} to reach the _{I SETB1} It makes it possible to increase people to. With the path controller D ₁ still off, the current I _SUM1 is equal to the sum of the currents I _A1 and I _B1 , the current I _A1 is controlled by the first type of current controller CCA ₁ and the current I _B1 is controlled by the current controller CCB ₁ of the second kind. The value of the turn-on voltage _{V A1,} either can equal to the value of the turn-on voltage _{V B1,} or may be different from the value of the turn-on voltage _{V B1.} In other words, the current _ISUM1 begins to increase at a voltage V1 equal to the smaller of the turn-on voltage V _A1 and the turn-on voltage V _B1 .

During the rising period when the voltage _{V IN1} is reached _V BK1 _{= V OFFB} to V2, the current controller CCB ₁ of the second type, the current _{I B1} is directed towards the routing controller _{D 1,} it It switched to cut-off mode for turning on the routing controller D ₁ by. Current _{I SUM1} is equal to the current _{I B1} and the current _{I A1,} both current _{I A1} and the current _{I B1} is controlled by the current controller CCA ₁ of the first type. Since the current _{I B1} flows through the path controller _{D 1,} current _{I D1} is gradually increased with the voltage _{V IN1.} In response, the first type of current controller CCA ₁ consequently decreases the value of the adjustable current source ISA ₁ so that the overall current I _AK1 is still maintained at a fixed value I _SETA1 . When the value of the current source ISA ₁ decreases to zero at V _IN1 = V3, the first type of current controller CCA ₁ switches to the cut-off mode. The current _ISUM1 is then controlled by the _subsequent drive stage.

In FIG. 9, during the rising and falling periods of the voltage V _CK when 0 <V _CK <V _DROPC , the third type current controller CC _{N + 1} is not fully turned on and the current I _CK is It operates as a voltage controlled element in a linear mode that varies in a specific manner with the voltage V _CK . For example, if the third type of current controller CC _{N + 1} is implemented using MOS transistors, the relationship between the current I _CK and the voltage V _CK is that of the MOS transistor when operating in the linear region. It can correspond to IV characteristics. During the rising and falling periods of the voltage V _CK when V _CK > V _DROPC , the current I _CK reaches I _SETC and the third type current controller CC _{N + 1} switches to constant current mode, Functions as a current limiter.

Similarly, the operations of the second to Nth drive stages ST _{2 to} ST _{N in} the LED lighting device 104 can be similarly illustrated in FIGS. 5 to 8, while (N + 1) of the LED lighting device 104. The operation of the current controller CC _{N + 1 in} the th drive stage ST _{N + 1} can be similarly illustrated in FIG.

In the present invention, the charge storage units CH _{1 to} CH _M may be connected in parallel to one or more of the light emitting elements A _{1 to} A _N and B _{1 to} B _N , respectively. The charge storage units CH _{1 to} CH _M can reduce the flicker of the LED lighting devices 101 to 104, where M is less than or equal to 2N.

In the embodiment where M = 2N, each of the light emitting elements A _{1 to} A _N and B _{1 to} B _N is connected in parallel to a corresponding charge storage unit. For illustrative purposes, FIG. 1 includes four light emitting elements A ₁ -A ₂ and B ₁ -B _{2 in} which an LED lighting device 101 is connected in parallel to charge storage units CH ₁ -CH ₄ , respectively. , N = 2 and M = 4 above. However, the number and configuration of the charge storage units does not limit the scope of the present invention.

In the embodiment where M <2N, each of the light emitting elements B _{1 to} B _N is connected in parallel to a corresponding charge storage unit. For illustrative purposes, FIG. 2 shows that the LED lighting device 102 includes four light emitting elements A ₁ -A ₂ and B ₁ -B ₂ , of which the light emitting elements B ₁ -B ₂ are charge storage units. 2 depicts the above example with N = 2 and M = 2 respectively connected in parallel to CH ₁ -CH ₂ . However, the number and configuration of the charge storage units does not limit the scope of the present invention.

In embodiments where a M <2N, the charge storage unit _CH 1 to CH _M of M is parallel to the light-emitting element having the longest turn-on time of the light-emitting element _A 1 to A _N and _B 1 .about.B _N Can be linked to. For illustrative purposes, FIG. 3 shows that the LED lighting device 103 includes four light emitting elements A ₁ -A ₂ and B ₁ -B ₂ , of which the light emitting elements A ₁ and B ₁ are charge storage units. 2 depicts the above example with N = 2 and M = 2 respectively connected in parallel to CH ₁ -CH ₂ . However, the number and configuration of the charge storage units does not limit the scope of the present invention.

In an embodiment where M = 1 <2N, the charge storage unit CH ₁ is connected in parallel to a plurality of light emitting elements having the longest turn-on time among the light emitting elements A _{1 to} A _N and B _{1 to} B _N. Can be done. For illustrative purposes, FIG. 4 shows that the LED lighting device 104 includes three light emitting elements A ₂ and B ₁ -B ₂ , of which the light emitting elements B ₁ -B ₂ are connected to the charge storage unit CH ₁ . Depict the above example with N = 2 and M = 1, connected in parallel. However, the number and configuration of the charge storage units does not limit the scope of the present invention.

FIG. 10 is a diagram illustrating current-time characteristics of the light emitting elements in the LED lighting devices 101 to 104. 10 shows the current-time characteristics of a light-emitting element that employs the first configuration, and the lower part of FIG. 10 shows the current-time characteristics of the light-emitting element that employs the second configuration. . In FIG. 10, I _LED represents a current flowing through a light emitting element adopting the first configuration, and I _LED ′ represents a current flowing through a light emitting element adopting the second configuration. Light emitting elements A1, A2, B1, or B2 in the LED lighting device 101, light emitting elements B1 or B2 in the LED lighting device 102, light emitting elements A1 or B1 in the LED lighting device 103, or light emitting elements B1 or B2 in the LED lighting device 104 Such a light emitting element adopting the first configuration is connected in parallel to a corresponding charge storage unit. Light-emitting elements that employ the second configuration, such as the light-emitting element A1 or A2 in the LED lighting device 102, the light-emitting element A2 or B2 in the LED lighting device 103, or the light-emitting element A2 in the LED lighting device 104, have a slight charge storage. Not connected to the unit in parallel.

During sufficiently larger before increasing period to rectified AC voltage V _AC is turned on the light emitting device, a light emitting device employing the second configuration, remains off, while employing the first configuration The light emitting element can be kept in the on state by the energy discharged from the corresponding charge storage unit. The corresponding path controller is arranged to prevent energy stored in the corresponding charge storage unit from being discharged through the corresponding current controller.

During the rising period or the falling period when the rectified AC voltage _VAC becomes sufficiently large, the light-emitting element adopting the first configuration or the light-emitting element adopting the second configuration It may be maintained in the oN state by the rectified AC voltage V _AC is charging.

During the falling period after the rectified AC voltage _VAC is no longer large enough to turn on the light emitting device, the light emitting device employing the second configuration remains in the off state, while the first configuration is The employed light emitting device can still be kept on by the energy discharged from the corresponding charge storage unit. The corresponding path controller is arranged to prevent energy stored in the corresponding charge storage unit from being discharged through the corresponding current controller.

  As depicted in FIG. 10, the introduction of a charge storage unit allows a light emitting device employing the first configuration to have a longer turn-on time than a light emitting device employing the second configuration.

In FIG. 11, two of the four light emitting elements A _{1 to} A ₂ and B _{1 to} B ₂ (N = 2 and M = 2) are connected in parallel to the respective charge storage units CH _{1 to} CH _2. or is a diagram illustrating the overall operation of the LED lighting device 103 in the case where the charge storage unit CH ₁ of one shared are connected in parallel. FIG. 12 is a diagram illustrating the overall operation of the LED lighting device 103 when the charge storage unit is not employed. E _{1 to} E ₃ represent the overall intensity / flux of the LED lighting device 103 under consideration. FIG. 12 is used as a comparison with FIG. 11 to illustrate how flicker can be improved with the charge storage unit under consideration depicted in FIGS. It should be noted that FIG. 12 is by no means the intended operation of the present invention.

The voltage _V AK1 _{~V AK2} and _V BK1 _{~V BK2,} the value is associated with rectified AC voltage _{V AC} varies periodically with time, used to drive the cycle of t0~t7 is described It is, where the period between t0~t3 belong to the rise period of the rectified AC voltage _{V AC,} the period between the t4~t7 belongs to the falling period of the rectified AC voltage _{V AC.} Table 1 below tabulates the operation modes of the light emitting elements A _{1 to} A ₂ and B _{1 to} B ₂ according to the configuration depicted in FIG. The following Table 2, the operation mode of the light-emitting element _A 1 to A ₂ and _B 1 .about.B ₂ in accordance with the configuration depicted in FIG. 12 are tabulated.

In Figure 12 and Table 2, at the beginning of the rising period, and at the end of the falling period, rectified AC voltage _{V AC} is insufficient to turn on the light-emitting element _A 1 to A ₂ and _B 1 .about.B ₂ . Without the charge storage unit under consideration, the light emitting elements A _{1 to} A ₂ and B _{1 to} B ₂ remain in the off state between t0 and t1 and between t6 and t7. Between t1 to t6, since the rectified AC voltage _{V AC} is increased or decreased, the light-emitting element _A 1 to A ₂ and _B 1 .about.B _2, together are sequentially turned on, the first driving stage ST ₁ and second driving stage ST _2, as depicted in the left side of FIG. 7, two turned-on light-emitting elements are connected in parallel (indicated by "P" in table 1 and table 2) first In the stage, or as depicted on the right side of FIG. 7, two turned-on light emitting elements are connected in series (indicated by “S” in Table 1 and Table 2) in the second stage. obtain. More specifically, the entire luminous intensity / light flux of the LED lighting device 103 changes in stages, and all the light emitting elements A _{1 to} A ₂ and B _{1 to} B ₂ operate in an on state in a series configuration. E3 is reached between t3 and t4.

In FIG. 11 and Table 1, the rectified AC voltage V _AC is insufficient to turn on the light emitting elements A _{1 to} A ₂ and B _{1 to} B ₂ at the beginning of the rising period and at the end of the falling period. . The charge storage unit under consideration, the light-emitting element A ₁ and B _1, regardless of the rectified AC voltage V _AC, during the entire driving period between t0 to t7, be held in the ON state. More specifically, if the rectified AC voltage _VAC is still small, the overall luminous intensity / flux of the LED lighting device 103 under consideration is maintained at E1 between t0 and t1 and between t6 and t7. obtain.

  As is well known to those skilled in the art, LED flicker is periodic due to waveforms characterized by changes in amplitude, average level, periodic frequency, shape, and / or duty cycle. As represented by the following equation, the flicker rate (Percent Flicker) and the flicker index (Flicker Index) are historically used evaluation indexes for quantifying flicker.

  In equation (1), MAX represents the maximum luminous intensity / light flux of the LED lighting devices 101-104, while MIN represents the minimum luminous intensity / flux of the LED lighting devices 101-104. In equation (2), AREA1 represents the sum of the luminous intensity / luminous flux within the duration of the drive cycle when the luminous intensity / luminous flux of the LED lighting devices 101-104 exceeds its average value, while AREA2 represents the LED lighting It represents the sum of luminous intensity / luminous flux within the duration of the driving cycle when the luminous intensity / luminous flux of the devices 101 to 104 is lower than the average value.

  As shown in FIG. 11, the introduction of the charge storage unit can increase MIN in equation (1) and AREA2 in equation (2), thereby increasing the flicker rate and flicker index of LED lighting devices 101-104. Can be lowered.

13 to 16 are diagrams of LED lighting devices 105 to 108 according to other embodiments of the present invention. Similar to the LED lighting devices 101 to 104 depicted in FIGS. 1 to 4, each of the LED lighting devices 105 to 108 similarly has a power supply circuit 110 and (N + 1) drive stages ST _{1 to} ST _{N + 1} ( N is a positive integer). However, in the LED lighting devices 105 to 107, each of the first to Nth drive stages ST _{1 to} ST _N includes a plurality of light emitting elements, a path controller, and two first-type current controllers. In this respect, it differs from the LED lighting devices 101-103. The LED lighting device 108 is an LED in that each of the second to Nth drive stages ST _{2 to} ST _N includes a plurality of light emitting elements, a path controller, and two first type current controllers. Different from the lighting device 104.

Each first type of current controller in LED lighting devices 105-108 includes an adjustable current source and a current detection and control unit, the IV curve of which can also be shown in FIG. . In the first type of current controller represented by CCA _{1 to} CCAN _N, the currents connected in series to the corresponding light emitting elements A _{1 to} A _N and the corresponding adjustable current sources ISA _{1 to} ISA _N , respectively. detection and control unit _UNA 1 _{~UNA N} are each configured to control the value of the adjustable current source _ISA 1 _{~ISA N} as the current _I AK1 _{~I AKN.} In the first type of the current controller represented by CCA ₁ '~CCA _N', respectively corresponding light emitting element _B 1 .about.B _N, and series to the corresponding adjustable current source ISA ₁ '~ISA _N' The coupled current detection and control units UNA ₁ ′ to UNA _N ′ are configured to control the values of the current sources ISA ₁ ′ to ISA _N ′ adjustable according to the currents I _AK1 ′ to I _AKN ′, respectively. .

  According to the multi-stage driving scheme described above, the present invention can flexibly turn on a plurality of light emitting devices using a plurality of current control units. With the above charge storage unit, the present invention can reduce the change in luminous intensity of the LED lighting device. Therefore, the present invention can provide an LED lighting device capable of improving an efficient operating voltage range, reliability, and flicker phenomenon.

  Those skilled in the art will readily recognize that numerous modifications and changes of the apparatus and method may be performed while retaining the teachings of the present invention. Accordingly, the above disclosure should be construed as limited only by the metes and bounds of the appended claims.

DESCRIPTION OF SYMBOLS 101 LED lighting device 102 LED lighting device 103 LED lighting device 104 LED lighting device 105 LED lighting device 106 LED lighting device 107 LED lighting device 108 LED lighting device 110 Power supply circuit 112 Bridge rectifier A ₁ -A _N Light emitting element B ₁ -B _N Light-emitting elements CH _{1 to} CH _M Charge storage units D _{1 to DN} Path controller CCA _{1 to} CCA _N First type current controller CCA ₁ ′ to CCA _N ′ First type current controller CCB _{1 to} CCB _N second type current controller CC _{N + 1} third type current controller ISA _{1 to} ISA _N adjustable current source ISA ₁ 'to ISA _N ' adjustable current source ISB _{1 to} ISB _N adjustable current Source IS _{N + 1} adjustable current source UNA ₁ -UNA _N current detection and control unit UNA ₁ '-U NA _N 'current detection and control unit UNB _{1 to} UNB _N voltage detection and control unit UN _{N + 1} detection and control unit V _AC rectified AC voltage V _{IN1 to} V _INN drive stage ST _{1 to} ST _N established voltage V _{AK1 to} V _AKN Current Controllers CCA _{1 to} CCAN _N Established Across Voltages V _{BK1 to} V _BKN Current Controllers CCB _{1 to} CC B _N Established Across Voltages V _CK Current Controller CC _{N + 1} transverse to the voltage I _AK1 was established ~I _AKN current controller _CCA 1 _~CCA current flowing through the _N I _BK1 ~I _BKN current controller _CCB 1 _~CCB current flowing through the _N I _A1 ~I _aN emitting element a ₁ to a current flowing through the _N I _B1 ~I _BN current flowing through the light-emitting element _B 1 ~B _N I _D1 ~I _N routing controller _D 1 to D current flowing through the _N I _SUM1 ~I _SUMN driving stage _ST 1 _~ST current flowing through the _N I _{SUM (N +} 1) total current of the LED lighting device

Claims (15)

A light emitting diode (LED) lighting device having a plurality of drive stages,
A first drive stage having a positive end and a negative end,
A first light emitting device coupled to the positive end and driven by a rectified alternating current (AC) voltage to provide light according to a first current;
A second light emitting device coupled to the negative end and driven by the rectified AC voltage to provide light according to a second current;
A first adjustable current source , connected between the first light emitting element and the negative end, so that the first current does not exceed a first value; A first current controller configured to control the current of
The second current is connected between the positive end and the second light emitting element, and configured to control the second current so that the second current does not exceed a second value. 2 current controllers,
When connected in parallel to at least the first light emitting element, the energy is discharged to the first light emitting element when the rectified AC voltage is insufficient to turn on the first light emitting element. A first charge storage unit configured to hold the first light emitting device in a turned-on state, and a third current to conduct, the first light emitting device, comprising a first path control unit having a second end coupled to the first end and the second current controller connected between the first adjustable current source, the first driving stage When,
Coupled in series with the first drive stage to conduct a fourth current and configured to control the fourth current such that the fourth current does not exceed a third value. third Bei example and a second drive stage comprising a current controller of,
The second current controller comprises:
A second adjustable current source coupled to the positive end and configured to conduct a sixth current;
Configured to regulate the sixth current in accordance with the second current or the third current and coupled to the second end of the first path controller and the second adjustable current source A second detection and control unit comprising a first end and a second end coupled to the second light emitting element;
The LED lighting device , wherein the rectified AC voltage is applied to a series configuration of the first drive stage and the second drive stage .   The first charge storage unit stops discharging the energy to the first light emitting device when the rectified AC voltage is sufficient to turn on the first light emitting device; The LED lighting device of claim 1, further configured to begin charging with a rectified AC voltage.   When connected to the second light emitting element in parallel and discharging the energy to the second light emitting element when the rectified AC voltage is insufficient to turn on the second light emitting element. The LED lighting device according to claim 1, further comprising a second charge storage unit configured to hold the second light emitting element in a turned-on state.   A third light emitting device coupled between the rectified AC voltage and the first driving stage and driven by the rectified AC voltage to provide light, A charge storage unit is connected in parallel to the first light emitting element and the third light emitting element, and the rectified AC voltage is ineffective for turning on the first light emitting element and the third light emitting element. If sufficient, discharge energy to the first light emitting element and the third light emitting element, thereby holding the first light emitting element and the third light emitting element turned on. The LED lighting device according to claim 1, further comprising a third drive stage configured as described above and including the third light emitting element.   When the first charge storage unit has the rectified AC voltage sufficient to turn on the first light emitting element and the third light emitting element, the first light emitting element and the third light emitting element. The LED lighting device of claim 4, further configured to stop discharging the energy to and begin to be charged by the rectified AC voltage. During the rising or falling period of the rectified AC voltage when the voltage established across the first current controller does not exceed the first voltage, the first current controller is Operating in a first mode in which one current varies with the voltage established across the first current controller;
During the ramp-up period when the voltage established across the first current controller exceeds the first voltage but does not exceed a second voltage, the first current controller is Operating in a second mode in which the first current is maintained at the first value;
During the ramp-up period when the voltage established across the first current controller exceeds the second voltage, the first current controller is turned off by the first current controller. The LED lighting device according to claim 1, wherein the LED lighting device operates in a third mode. During the falling period when the voltage established across the first current controller exceeds the second voltage but does not exceed a third voltage, the first current controller is , the first current is operating in the second mode is maintained at the first value, the third voltage is greater than said second voltage, LED lighting device according to claim 6. During the rising or falling period of the rectified AC voltage when the voltage established across the second current controller does not exceed a fourth voltage, the second current controller is Operating in a first mode in which two currents vary with the voltage established across the second current controller;
During the rising period or the falling period when the third current does not exceed the second value, the second current controller maintains the second current at the second value. Operate in the second mode,
During the rising period or the falling period when the third current exceeds the second value, the second current controller is in a third mode in which the second current controller is turned off. The LED lighting device according to claim 1 which operates. During the rising or falling period of the rectified AC voltage when the voltage established across the third current controller does not exceed the sixth voltage, the third current controller is Operating in a first mode in which a current of 4 varies with the voltage established across the third current controller;
During the rising or falling period when the voltage established across the third current controller exceeds a sixth voltage, the third current controller causes the fourth current to The LED lighting device according to claim 1, wherein the LED lighting device operates in a second mode maintained at the third value. The first current controller comprises:
A second end connected to the first end and the negative end connected between the first light emitting device and the first path controller, and configured to conduct a fifth current . Said first adjustable current source having an end ;
A first detection and control coupled in parallel with the first adjustable current source and configured to regulate the fifth current according to a voltage established across the first current controller. The LED lighting device according to claim 1, comprising a unit. The LED lighting device includes a first detection and control unit connected between the second light emitting element and the negative end,
The first current controller comprises:
A first end connected to the first light emitting device and the first path controller, and the second light emitting device and the first light emitting device are configured to conduct a fifth current . Said first adjustable current source having a second end coupled between a sensing and control unit ;
Are connected in series to said first adjustable current source, and said first current configured the first and to adjust the fifth current according to the second current sensing and control unit The LED lighting device according to claim 1, comprising: The third current controller comprises:
A third adjustable current source configured to conduct the fourth current;
A third detection and control unit coupled in series with the third adjustable current source and configured to control the third adjustable current source according to the fourth current. The LED lighting device according to 1.   The LED lighting device according to claim 1, wherein the first path controller includes a diode, a diode-connected field effect transistor (FET), or a diode-connected bipolar junction transistor (BJT). When the first path controller is turned off, the first light emitting device is connected in parallel to the second light emitting device;
2. The LED lighting device according to claim 1, wherein when the first path controller is turned on, the first light emitting element is connected in series to the second light emitting element. When the first path controller is turned off, the third current is zero and the fourth current is equal to the sum of the first current and the second current;
The LED lighting of claim 1, wherein the first current, the second current, the third current, and the fourth current are equal when the first path controller is turned on. apparatus.

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