JP5639389B2 - LED driving device and LED lighting device - Google Patents

Description

  The present invention relates to an LED driving device and an LED lighting device.

  Conventionally, as an LED driving device for lighting an LED by an AC power supply, for example, as disclosed in Patent Document 1, a pulsating voltage output from a rectifier circuit is connected to a series-connected LED and a constant current circuit. A circuit for applying to is known.

JP 2010-62349 A

  However, in the technique disclosed in Patent Document 1, when the pulsating current voltage exceeds the forward voltage drop Vf of the LED, a voltage drop occurs in the constant current circuit, so that power loss corresponding to the voltage drop occurs. There is a problem that it occurs.

  An object of the present invention is to provide an LED driving device and an LED lighting device with little loss.

The present invention for solving the above problems is an LED driving device for lighting an LED with a pulsating voltage obtained by rectifying an AC voltage with a rectifier circuit, and an LED group composed of a plurality of LEDs connected in series; A constant current circuit connected in series to the LED group; a capacitor connected in series to the LED unit; and applying the pulsating current to the LED unit and the capacitor Control for switching between a first connection state in which a capacitor is charged and a second connection state in which the charged capacitor is connected in parallel to the LED unit and the charge stored in the capacitor is discharged through the LED unit. And a control circuit for performing the above.
According to such a configuration, it is possible to provide an LED driving device with little loss.

According to another invention, in addition to the above invention, the control circuit connects the capacitor in parallel to the LED unit when the pulsating voltage is lower than a terminal voltage of the capacitor. .
According to such a configuration, the first and second connection states can be switched according to the pulsating voltage, so that the control can be reliably performed and the circuit configuration can be simplified.

In addition to the above invention, another invention has a plurality of the LED units, and the number of the LED units corresponding to the value of the pulsating voltage is connected in series when the capacitor is charged, and a part of the LED units is discharged. Alternatively, the capacitors are connected in parallel to all the LED units.
According to such a configuration, since the LED can be lit even when the pulsating voltage is low, the lighting efficiency can be improved.

In addition to the above invention, another invention has a plurality of the LED units, wherein the LED units are connected in series when the capacitor is charged, and the capacitors are connected to some of the LED units when discharged. It is characterized by being connected in parallel.
According to such a configuration, since the terminal voltage of the capacitor can be set to a desired value according to the number of LEDs of the LED units connected in parallel at the time of discharging, the performance of the device can be set to a desired value. Can do.

In addition to the above-mentioned invention, another invention has a plurality of the capacitors, wherein the capacitors are connected in series when charging these capacitors, and the capacitors are connected in parallel when discharging. And
According to such a configuration, since the voltage during charging and discharging can be changed, an efficient device can be obtained even when the difference between the pulsating voltage and the forward voltage drop of the LED group is large. Can do.

In addition to the above-described invention, in another invention, when the capacitor is charged, when the pulsating voltage becomes a predetermined voltage or less, the pulsating voltage is cut off, and the first connection state It further has a shut-off circuit for forcibly shifting to the second connection state.
According to such a configuration, it is possible to shorten the transition period from the first connection state to the second connection state and improve the efficiency of the device.

Another invention is an LED lighting device characterized in that an LED is turned on using the LED driving device described above.
According to such a configuration, it is possible to provide an LED lighting device with little loss.

It is a principle diagram for explaining the operation principle of the present invention. It is the equivalent circuit at the time of charge and discharge of the principle figure of FIG. It is a block diagram which shows the LED drive device which concerns on 1st Embodiment of this invention. It is the equivalent circuit at the time of charge of the LED drive device shown in FIG. 3, and discharge. It is a figure which shows the time change of the voltage of each part of the LED drive device shown in FIG. It is a figure explaining operation | movement of the LED drive device shown in FIG. It is a block diagram which shows the LED drive device which concerns on 2nd Embodiment of this invention. It is a figure explaining operation | movement of the LED drive device shown in FIG. It is a block diagram which shows the LED drive device which concerns on 3rd Embodiment of this invention. It is a figure explaining operation | movement of the LED drive device shown in FIG. It is a block diagram which shows the LED drive device which concerns on 4th Embodiment of this invention. It is a block diagram which shows the LED drive device which concerns on 5th Embodiment of this invention. It is a figure explaining operation | movement of the LED drive device shown in FIG. It is a block diagram which shows the LED drive device which concerns on 6th Embodiment of this invention. It is a figure explaining operation | movement of the LED drive device shown in FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(A) Operation Principle of the Present Invention First, the operation principle of the present invention will be described with reference to FIGS. FIG. 1 is a principle diagram for explaining an operation principle of an LED (Light Emitting Diode) driving device according to the present invention. As shown in FIG. 1, an LED drive device 1 according to the present invention includes a terminal 2 to which commercial power is applied, a rectifier circuit 3, a constant current circuit 4, LEDs 5-1 to 5-n (LED group), and a control circuit. 6 and the capacitor 7 are main components. The constant current circuit 4 and the LEDs 5-1 to 5-n constitute an LED unit 8.

  Here, the rectifier circuit 3 performs full-wave rectification or half-wave rectification of, for example, an AC voltage of 100 V applied to the input terminal 2 and outputs a pulsating voltage. The constant current circuit 4 generates a constant current and supplies it as a drive current to the LEDs 5-1 to 5-n. The LEDs 5-1 to 5-n are configured by connecting a plurality of LEDs in series. As the number connected in series, for example, the number Nm (= INT (Vm / 2 / Vf)) obtained by dividing 1/2 of the maximum value Vm of the pulsating voltage by the forward voltage drop Vf of each LED. What is necessary is just to set so that it may become the following (INT () shows the value which rounded off the decimal point of the value in a parenthesis). The number of LEDs is obtained in this way because when the device is in a steady state, a voltage equal to or higher than the total voltage VF (= Vf × n) of the LED forward drop voltage Vf appears in the capacitor 7. Therefore, in order to charge by connecting them in series in such a state, the voltage applied to the LED needs to be smaller than Vm / 2. Specifically, for example, when the forward voltage drop Vf of each LED is 3.2 V and Vm is 141 V, Nm = INT (141/2 / 3.2)) = 22. As the number, for example, 20 (n = 20) can be selected.

  The control circuit 6 is a circuit that controls the connection relationship between the capacitor 7 and the LED unit 8. Specifically, when the pulsating voltage Vp output from the rectifier circuit 3 is lower than the terminal voltage Vc of the capacitor 7 (when Vp <Vc), the capacitor 7 is connected to the LED unit 8 (in series connection). The constant current circuit 4 and the LEDs 5-1 to 5-n) are connected in parallel, and the pulsating voltage Vp is the sum of the terminal voltage Vc of the capacitor 7 and the forward drop voltage Vf of the LEDs 5-1 to 5-n (= When it is higher than the sum of VF) (when Vp> Vc + VF), the capacitor 7 is connected in series to the LED unit 8.

  The capacitor 7 is constituted by, for example, an electrolytic capacitor or a ceramic capacitor. When the capacitor 7 is connected in series, the capacitor 7 is charged by a pulsating voltage. When the capacitor 7 is connected in parallel, the charged charge is discharged via the LED unit 8. .

  Next, the operation of the above principle diagram will be described with reference to FIG. When the commercial power supply is applied to the terminal 2 in a state where no charge is accumulated in the capacitor 7, the rectifier circuit 3 rectifies the AC voltage of the commercial power supply and outputs it as a pulsating voltage. At the start of the operation, no charge is accumulated in the capacitor 7 and the terminal voltage of the capacitor 7 is 0 V. Therefore, when the pulsating voltage rises, the control circuit 6 connects the capacitor 7 in series with the LED unit 8. Connecting. As a result, the circuit shown in FIG. 1 is represented as an equivalent circuit as shown in FIG. In this state, when the pulsating voltage rises, the capacitor 7 is charged in the direction indicated by the plus / minus symbols in FIG. When the voltage applied to the LEDs 5-1 to 5-n exceeds VF, the LEDs 5-1 to 5-n are turned on.

  When the pulsating voltage changes from rising to falling, the voltage applied to the LED unit 8 and the capacitor 7 decreases. When the voltage obtained by adding the terminal voltage Vc of the capacitor 7 to the sum VF of the forward drop voltages of the LEDs 5-1 to 5-n becomes lower than the pulsating voltage (when VF + Vc <Vp), the control circuit 6 The LED unit 8 is connected in parallel. As a result, the circuit shown in FIG. 1 is represented as an equivalent circuit as shown in FIG. In such a state, the electric charge accumulated in the capacitor 7 is discharged through the constant current circuit 4 and the LEDs 5-1 to 5-n, thereby turning on the LEDs 5-1 to 5-n.

  When the operation as described above is repeated, the apparatus is in a steady state, the charge charged / discharged with respect to the capacitor 7 is balanced, and the terminal voltage of the capacitor 7 is stabilized at a voltage close to VF. That is, the discharge timing is determined by whether or not Vp <Vc is satisfied, and the charging timing is determined by whether or not Vp> Vc + VF is satisfied. Therefore, when the terminal voltage Vc of the capacitor 7 increases, the discharge time becomes longer. On the other hand, since the charging time is shortened, the voltage is controlled to decrease. Further, when the terminal voltage Vc of the capacitor 7 is lowered, the discharging time is shortened while the charging time is lengthened, so that the voltage is controlled to increase. In this way, control is performed so that the terminal voltage of the capacitor 7 becomes constant.

  Incidentally, when a voltage is applied from the power source to the LEDs 5-1 to 5-n, as shown in FIG. 2A, the pulsating voltage is the constant current circuit 4, the LEDs 5-1 to 5-n, and the capacitor. 7 is divided. As described above, since the terminal voltage Vc of the capacitor 7 is a value close to VF in the steady state, the voltage applied to the constant current circuit 4 is reduced by about VF as compared with the case where the capacitor 7 is not used. Thereby, the loss in the constant current circuit 4 is reduced. In other words, the loss in the constant current circuit 4 is represented by the product of the voltage applied to the constant current circuit 4 and the flowing current, so that the loss decreases as the voltage decreases. In addition, since the charge accumulated in the capacitor 7 is discharged through the LEDs 5-1 to 5-n as shown in FIG. 2B, the accumulated charge can be used effectively. The lighting time can be extended to reduce the occurrence of flicker.

  As described above, according to the LED driving device 1 according to the present invention, the voltage applied to the constant current circuit 4 is divided and reduced by the capacitor 7 connected in series. The loss in 4 can be reduced. In addition, the charged capacitor 7 is connected in parallel to the constant current circuit 4 and the LEDs 5-1 to 5-n and discharged, thereby effectively utilizing the accumulated charge and extending the lighting time to flicker. Generation can be reduced.

  In the above example, as described above, the control circuit 6 switches the parallel and series connection states based on the mutual relationship between Vc, Vp, and VF. The connection state may be switched based on the voltage of the unit, or the connection state may be switched based on a voltage other than these. Specifically, the connection state may be switched based on the relationship between only Vp and Vc, or the connection state may be switched based on the relationship between only Vp and VF. Alternatively, a predetermined voltage Va instead of Vc and VF may be obtained, and the connection state may be switched based on the relationship between this and Vp.

  Further, the connection state may be switched based on current instead of voltage, or the connection state may be switched based on time. Specifically, for example, as a method of switching the connection by the current, for example, when the current flowing from the rectifier circuit 3 becomes a predetermined value or less, the connection is made in parallel, and when the current exceeds the predetermined value, the connection is made in series. You may make it change into a connection. Furthermore, as a method of switching the connection based on time, for example, the counter is reset at the timing when the pulsating voltage becomes 0 V, and the count operation is started. When the count value reaches a predetermined value, the parallel connection is performed in series. After switching, when the count value becomes another predetermined value, it may be switched from parallel to serial, and when the pulsating voltage becomes 0 again, the counter may be reset and restarted. In addition, the above is an example and it cannot be overemphasized that methods other than this may be sufficient. In short, parallel and series switching may be performed based on predetermined conditions (for example, voltage, current, and time) so that the balance of charges charged and discharged with respect to the capacitor 7 is balanced.

(B) First Embodiment FIG. 3 is a diagram showing a configuration example of a first embodiment of the present invention. As shown in this figure, the LED drive device 10 according to the first embodiment includes power terminals 11 and 12, diodes 13a to 13d, a constant current circuit 14, an LED block 15, diodes 16 and 17, resistors 18 and 19, and capacitors. 20, a transistor 21, and a diode 22. Here, for example, an AC voltage (for example, 100 V) of a commercial power supply is applied to the power supply terminals 11 and 12. The diodes 13a to 13d constitute a bridge circuit, full-wave rectifies the input AC voltage, and generates and outputs a pulsating voltage. The constant current circuit 14 includes resistors 14a and 14b and transistors 14c to 14e, and controls so that a constant current flows through the resistor 14b. Specifically, when a certain current or more is passed through the resistor 14b, the transistor 14e is turned on, and current is passed between the collector and emitter of the transistor 14e via the resistor 14a, so that the base currents of the transistors 14c and 14d are bypassed. Is done. As a result, the transistors 14c and 14d are turned off to limit the current. By such an operation, the current flowing through the resistor 14b is controlled to be constant. The LED block 15 includes n LEDs 15-1 to 15-n connected in series. In this embodiment, n = 20, and the forward voltage drop Vf of each LED is 3.2V.

  The diodes 16 and 17 are reverse-biased and forward-biased according to the pulsating voltage output from the diodes 13a to 13d, and the capacitor 20 is connected in parallel with the constant current circuit 14 and the LED block 15 or connected in series. Take control. Resistors 18 and 19 are bias resistors of the transistor 21. The capacitor 20 is charged by a pulsating voltage when connected in series with the constant current circuit 14 and the LED block 15, and discharged to the constant current circuit 14 and LED block 15 when connected in parallel. In this example, the capacitor 20 is constituted by, for example, an electrolytic capacitor having a withstand voltage of 100 V and a capacity of 22 μF. Needless to say, other breakdown voltages and capacities may be used. In addition, for example, a ceramic capacitor can be used instead of the electrolytic capacitor.

  In the example of FIG. 3, the transistor 21 is configured by an NPN bipolar transistor, and controls the capacitor 20 to be connected in parallel with the constant current circuit 14 and the LED block 15 or in series connection. The diode 22 is in a forward bias state when a current is passed to the capacitor 20 (at the time of charging), a reverse bias state is established between the emitter and base of the transistor 21, and the transistor 21 is cut off.

  Next, the operation of the first embodiment will be described with reference to FIGS. When supply of commercial power to the power supply terminals 11 and 12 is started in a state where no charge is accumulated in the capacitor 20 (a state where the terminal voltage Vc of the capacitor 20 is 0), full-wave rectification is performed by the diodes 13a to 13d. The generated pulsating voltage is output.

  When the terminal voltage Vc of the capacitor 20 is 0, when the pulsating voltage increases, the diode 16 is in a reverse bias state, while the diode 17 is in a forward bias state. In such a state, when the pulsating voltage Vp increases and the voltage becomes higher than the total forward voltage VF (= Vf × n) of the LEDs 15-1 to 15-n constituting the LED block 15, the constant current circuit 14, current is passed to the LEDs 15-1 to 15-n via the LED 14, and these are lit. The current output from the LEDs 15-1 to 15-n flows into the anodes of the diodes 13d and 13c via the diode 17, the capacitor 20, and the diode 22. Thereby, the capacitor 20 is charged. At this time, since the diode 22 is in a forward bias state, the base 21 and the emitter of the transistor 21 are reversely biased, and the transistor 21 is cut off. As a result, the constant current circuit 14, the LED block 15, and the capacitor 20 are connected in series as shown in FIG. 4A, so that the capacitor 20 is charged by the current output from the constant current circuit 14. The

  When the pulsating voltage changes from rising to falling, and the pulsating voltage Vp becomes lower than the sum of the total forward voltage VF of the LEDs 15-1 to 15-n and the terminal voltage Vc of the capacitor 20 (Vp <VF + Vc). Since the voltage applied to the LEDs 15-1 to 15-n is lower than VF, the LEDs 15-1 to 15-n are turned off. When the pulsating voltage further decreases and becomes lower than the terminal voltage Vc of the capacitor 20, the diode 16 enters the forward bias state, and the diode 17 enters the reverse bias state. At this time, since no current is passed to the diode 22, the transistor 21 is turned on by the current passed from the capacitor 20 through the resistor 18 between the base and emitter of the transistor 21. As a result, the constant current circuit 14, the LED block 15, and the capacitor 20 are connected in parallel as shown in FIG. 4B. As a result, the electric charge accumulated in the capacitor 20 is discharged through the constant current circuit 14 and the LED block 15. As a result, the LEDs 15-1 to 15-n are turned on.

  FIG. 5 is a diagram showing temporal changes in the terminal voltage Vc of the capacitor 20 and the charging current and discharging current of the capacitor 20 when the supply of the power supply voltage is started in a state where no charge is accumulated in the capacitor 20. It is. As shown in this figure, when the supply of the power supply voltage is started, the terminal voltage Vc of the capacitor 20 increases with time and is stabilized at a constant voltage (substantially the same voltage as VF). The charging current of the capacitor 20 is defined by the current value of the constant current circuit 14 and becomes a constant current. In addition, the charging current flows for a long time at the beginning of power supply, but decreases as the terminal voltage Vc of the capacitor 20 increases, and converges to a constant value when a predetermined time elapses. In addition, the discharge current of the capacitor 20 does not flow at the beginning of power supply, but starts to flow when the terminal voltage Vc of the capacitor 20 reaches VF, and converges to a certain value after a certain period of time. The current value of the discharge current is defined by the current value of the constant current circuit 14 as in the case of the charging current. Further, the time during which the discharge current flows converges to a certain value when a certain time elapses. Needless to say, when the voltage of the capacitor 20 is stable, the amount of charge charged in the capacitor 20 is equal to the amount of charge discharged.

  FIG. 6 is a diagram for explaining lighting angles of the LEDs 15-1 to 15-n in a state where the terminal voltage Vc of the capacitor 20 is stable. As shown in this figure, in the first embodiment, when the pulsating voltage Vp is higher than Vc + VF (Vp> Vc + VF), the charging current flows through the capacitor 20 and the LEDs 15-1 to 15-n are in the lighting state. Become. Further, when the pulsating voltage Vp is lower than Vc (Vp <Vc), a discharge current flows from the capacitor 20 and the LEDs 15-1 to 15-n are turned on. In addition, when the voltage of the capacitor 20 is stable, the electric charge flowing into and out of the capacitor 20 is equal, so that τ during charging and discharging shown in FIG. 6 is equal. In the case of the first embodiment shown in FIG. 3, the input power conduction angle is 35 degrees, and the lighting angle is 70 degrees.

  As described above, according to the first embodiment, when the capacitor 20 is charged, the voltage applied to the constant current circuit 14 is shared by the capacitor 20. Loss can be reduced. Further, when the capacitor 20 is discharged, the charge accumulated in the capacitor 20 is discharged via the LEDs 15-1 to 15-n, so that the charge accumulated in the capacitor 20 is effectively used and the lighting time is increased. The occurrence of flicker can be prevented by extending the length.

(C) 2nd Embodiment FIG. 7: is a figure which shows the structural example of the LED drive device which concerns on 2nd Embodiment of this invention. In FIG. 7, parts corresponding to those in FIG. As shown in FIG. 7, the LED drive device 10A according to the second embodiment has a constant current circuit 34 and an LED block 35 added as compared with the case of FIG. 3, and the cathode of the LED 35-m, the emitter of the transistor 14e, Are connected by a diode 36, and the connection between the input side of the constant current circuit 14 and the cathodes of the diodes 13a and 13b is released. Other configurations are the same as those in FIG.

  Here, the constant current circuit 34 has the same configuration as that of the constant current circuit 14 and is set so that a current having the same value as the constant current circuit 14 flows. The LED block 35 includes m LEDs 35-1 to 35-m connected in series. In the second embodiment shown in FIG. 7, m = 4 and n = 16. Since the LEDs 35-1 to 35-m are configured by the same types of LEDs as the LEDs 15-1 to 15-n, the respective forward drop voltages Vf are the same (for example, 3.2 V).

  Next, the operation of the second embodiment will be described. In the second embodiment shown in FIG. 7, when the capacitor 20 is charged, the transistor 21 is turned off, the LED block 15, the LED block 35, and the capacitor 20 are connected in series, and the current from the constant current circuit 34. As a result, the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on, and the capacitor 20 is charged.

  On the other hand, when the capacitor 20 is discharged, the transistor 21 is turned on, the capacitor 20 is connected in parallel with the constant current circuit 14 and the LED block 15, and the charge accumulated in the capacitor 20 is the diode 16, the constant current circuit. 14, discharged via the LED block 15 and the transistor 21.

  Here, as described above, in the second embodiment shown in FIG. 7, since m = 4 and n = 16, the capacitor 20 is charged with 20 LEDs connected in series during charging. The Further, at the time of discharging, the capacitor 20 is discharged in a state where 16 LEDs are connected in series. Therefore, in the second embodiment shown in FIG. 7, as shown in FIG. 8, the terminal voltage Vc of the capacitor 20, the total forward drop voltage VF1 of the LEDs 15-1 to 15-n, and the LEDs 35-1 to 35-35. When the pulsating voltage Vp becomes higher than the value (VF1 + VF2 + Vc) obtained by adding the total forward drop voltage VF2 of m (VF1 + VF2 + Vc <Vp), the capacitor 20 is charged. When the voltage is lower than the terminal voltage (Vc> Vp), the capacitor 20 is discharged. In the second embodiment, the input power conduction angle is 70 degrees, the 16 lamp lighting angle (the angle at which the LEDs 15-1 to 15-n are lit) is 140 degrees, and the four lamp lighting angle (the LEDs 35-1 to 35-35). The angle at which n lights up is 70 degrees.

  The above is based on the assumption that the balance between the charge to be charged and the charge to be discharged is balanced, but in reality, the charge cannot be sufficiently discharged due to the short discharge period. More specifically, when the voltage of the capacitor 20 is equal to VF1 (= 51.2V), the discharge period is a period in which the pulsating voltage is VF1 or less, but since this period is short, the discharge period is accumulated in the capacitor 20. The charged electric charge is not sufficiently discharged, and the terminal voltage of the capacitor 20 rises above VF1. For this reason, since the charge start voltage (= VF1 + VF2 + Vc) increases, the charge period is shortened, and as a result, the balance of charges is balanced.

  In 2nd Embodiment, efficiency can be adjusted by adjusting the division | segmentation number of LED. Specifically, if the value of n is increased and the number of m is decreased by that amount, the conduction angle is decreased, while the charging start voltage is increased and the loss in the constant current circuit 34 is decreased. Can be improved.

  As described above, according to the second embodiment of the present invention, the LED is divided into two modules, a constant current circuit is provided for each of the modules, and discharge is performed on one module. Therefore, the conduction angle and efficiency can be adjusted by adjusting the number of divisions of the LEDs.

(C) Third Embodiment FIG. 9 is a diagram illustrating a configuration example of an LED drive device according to a third embodiment of the present invention. In FIG. 9, parts corresponding to those in FIG. As shown in FIG. 9, the LED drive device 10B according to the third embodiment excludes the diodes 16 and 17, the resistors 18 and 19, the capacitor 20, the transistor 21, and the diode 22 as compared with the case of FIG. 7. The LED 15-n is directly connected to the anodes of the diodes 13c and 13d. The input side of the constant current circuit 14 is connected to the input side of the constant current circuit 34, and the cathode of the LED 35-m is connected to the base of the transistor 14e. Further, a constant current circuit 44 and a charge circuit 45 are added, and the cathode of the diode 47 of the charge circuit 45 is connected to the base of the transistor 34e. The output side of the constant current circuit 44 is connected to the capacitor 20 via the diode 46. Furthermore, one end of the capacitor 20 is connected to the cathodes of the diodes 13 a and 13 b via the diode 48, and the other end is connected to the anodes of the diodes 13 c and 13 d via the diode 49.

  Here, the constant current circuits 14, 34, and 44 have the same configuration and output constant currents having the same value. The charge circuit 45 includes a capacitor 20 and diodes 46 and 47, one end of the capacitor 20 is connected to the output side of the constant current circuit 44 via the diode 46, and the other end is connected to the base of the transistor 34 e via the diode 47. It is connected. In the embodiment shown in FIG. 9, n = 16 and m = 4. That is, the LED block 15 is composed of 16 LEDs, and the LED block 35 is composed of 4 LEDs.

  Next, the operation of the third embodiment will be described. When the power supply voltage is applied to the LED driving device 10B and the pulsating voltage rises and becomes higher than the total forward drop voltage VF1 (= 51.2V) of the LEDs 15-1 to 15-n, the constant current circuit 14 is turned on. Thus, the LEDs 15-1 to 15-n are turned on. At this time, the LEDs 35-1 to 35-m are in the off state, and no current flows through the capacitor 20. In such a state, the pulsating voltage further rises and is higher than the total direction drop voltage VF2 (= 12.8V) and VF1 (= VF1 + VF2 (= 64V)) of the LEDs 35-1 to 35-m. Becomes higher, the current output from the constant current circuit 34 flows to the anodes of the diodes 13c and 13d via the LEDs 35-1 to 35-m, the resistor 14b, and the LEDs 15-1 to 15-n. As a result, the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on. At this time, since the current from the LED 35-m flows to the resistor 14b, the transistor 14e is turned on. As a result, since the current output from the resistor 14a almost flows through the transistor 14e, a sufficient base current does not flow through the transistors 14c and 14d, and the transistors 14c and 14d are turned off. As a result, the constant current circuit 14 is cut off. Thereby, the current from the constant current circuit 14 to the LED block 15 is cut off.

  In this state, when the pulsating voltage further rises and the voltage of the capacitor 20 is Vc, and the pulsating voltage becomes higher than VF1 + VF2 + Vc, the constant current circuit 34 is operated by the same operation as described above. Is further cut off, and the LEDs 15-1 to 15-n, LEDs 35-1 to 35-m, and the capacitor 20 are connected in series, and the current from the constant current circuit 44 is supplied. Accordingly, the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on, and the capacitor 20 is charged.

  Next, when the pulsating voltage decreases and becomes lower than VF1 + VF2 + Vc, the diodes 46 and 47 are cut off and the constant current circuit 44 is cut off. As a result, the current from the diode 47 to the resistor 34b is cut off, and the constant current circuit 34 is turned on. Thereby, the current output from the constant current circuit 34 flows to the LEDs 15-1 to 15-n via the LEDs 35-1 to 35-m and the resistor 14b. As a result, the constant current circuit 14 continues to be cut off, and the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are lit.

  Further, when the pulsating voltage decreases and becomes lower than VF1 + VF2, the current does not pass to the LEDs 35-1 to 35-m, so that the LEDs 35-1 to 35-m are turned off and the constant current circuit 34 is cut off. It will be in the state. As a result, since the current from the LED 35-m to the resistor 14b is cut off, the constant current circuit 14 is turned on, and the LEDs 15-1 to 15-n are turned on by the current output from the constant current circuit 14. .

  When the pulsating voltage further decreases and becomes lower than VF1, the current from the power source to the constant current circuit 14 is cut off, but the electric charge accumulated in the capacitor 20 is constant current via the diodes 48 and 49. It is supplied to the circuit 14 and the LEDs 15-1 to 15-n. As a result, the electric charge accumulated in the capacitor 20 is discharged via the diode 48, the constant current circuit 14, the LED block 15, and the diode 49. As a result, the LEDs 15-1 to 15-n are lit by the charges accumulated in the capacitor 20. Such an operation is repeated according to a change in the pulsating voltage.

  FIG. 10 is a diagram for explaining the operation at this time. As shown in FIG. 10, when the pulsating voltage is less than VF1, the LEDs 15-1 to 15-n are lit by the electric charge accumulated in the capacitor 20, and the pulsating voltage exceeds VF1 + VF2. When the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on and the pulsating voltage exceeds VF1 + VF2 + Vc, the LEDs 15-1 to 15-n, the LEDs 35-1 to 35-m, and the capacitor 20 are The capacitors 15 are connected in series, and the capacitor 20 is charged by the pulsating voltage, and the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on.

  As described above, according to the third embodiment, since the LEDs 15-1 to 15-n can be constantly turned on, the lighting efficiency of the LEDs can be increased. Further, since the angle at which the LED is lit can be widened, the power factor can be increased. In the circuit shown in FIG. 9, a power factor of about 96% can be realized. In addition, since the conduction angle is wide, the light controllable range by the dimmer can be widened.

(D) 4th Embodiment FIG. 11: is a figure which shows the structural example of the LED drive device which concerns on 4th Embodiment of this invention. In FIG. 11, parts corresponding to those in FIG. 7 are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 11, the LED drive device 10C according to the fourth embodiment excludes the diodes 16 and 17, the resistors 18 and 19, the capacitor 20, the transistor 21, and the diode 22 as compared with the case of FIG. 7. The input sides of the constant current circuits 14 and 34 are connected to each other. The cathode of the diode 36 is connected not to the emitter of the transistor 14e but to the base. Further, a charge circuit 50, diodes 61 and 62, transistors 63 and 65, Zener diodes 64 and 67, and resistors 66 and 68 to 70 are newly added. The charge circuit 50 is connected to the LED 15-n by a diode 37.

  Here, the charge circuit 50 includes the capacitor 20 and the diode 51, and is charged by the pulsating voltage, and discharges the charged charges via the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m. To do. In the fourth embodiment, n = m = 10. That is, each of the LED blocks 15 and 35 is composed of 10 LEDs.

  The transistor 63 is configured by, for example, an N-channel MOS-FET, and is turned on when a voltage is applied to the Zener diode 64, and becomes the cathode of the LED 15-n and the LED 35-m via the diodes 61 and 62. Connect. The transistor 65 is composed of, for example, an NPN bipolar transistor. When a voltage is applied to the resistor 66, the transistor 65 is turned on, the gate and the source of the transistor 63 are short-circuited, and the transistor 63 is turned off. To do. Here, when the terminal voltage of the capacitor 20 is Vc, the transistor 65 is turned on when the pulsating voltage becomes higher than Vc, for example, so that the transistor 63 is turned off. Element values such as resistors 66, 68, 69 and Zener diode 67 are set. Further, the element values of the Zener diode 64 and the resistor 70 are set so that the transistor 63 is turned on when the pulsating voltage becomes equal to or lower than a predetermined voltage lower than Vc, for example.

  Next, the operation of the fourth embodiment will be described. When the pulsating voltage increases and becomes equal to or higher than Vc, the transistor 65 is turned on, so that the transistor 63 is turned off. When the transistor 63 is turned off, the diodes 61 and 62 are opened, so that the LEDs 15-1 to 15-n, the LEDs 35-1 to 35-m, and the capacitor 20 are connected in series. When the pulsating voltage rises in such a state, when the voltage applied to the LEDs 15-1 to 15-n exceeds VF1, the current output from the constant current circuit 14 is the LEDs 15-1 to 15-n, It flows to the anodes of the diodes 13c and 13d via the diode 37 and the capacitor 20. As a result, the LEDs 15-1 to 15-n are turned on and the capacitor 20 is charged.

  When the pulsating voltage further rises to Vc + VF1 + VF2 or more, the voltage applied to the LEDs 35-1 to 35-m exceeds VF2, so that the current output from the constant current circuit 34 is the LED block 35, the diode 36, and the resistor 14b. Then, the light flows through the LED block 15 and the capacitor 20 to the anodes of the diodes 13c and 13d. Accordingly, the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on, and the capacitor 20 is charged. At this time, since the constant current circuit 14 is cut off, the current from the constant current circuit 14 to the LED block 15 is cut off.

  When the pulsating voltage starts to decrease and becomes Vc + VF1 + VF2 or less, the LEDs 35-1 to 35-m are turned off and the LEDs 15-1 to 15-n are turned on. When the voltage further decreases to Vc + VF1 or less, the LEDs 15-1 to 15-n are further turned off. When the voltage further decreases to Vc or less, the transistor 65 is turned off, so that the transistor 63 is turned on. As a result, the diodes 61 and 62 are connected to the anodes of the diodes 13c and 13d via the transistor 63, so that the constant current circuit 34 and the LED block 35, the constant current circuit 14 and the LED block 15, and the capacitor 20 are connected in parallel. It will be in the state. As a result, the electric charge accumulated in the capacitor 20 flows to the LED block 15 via the constant current circuit 14 and also flows to the LED block 35 via the constant current circuit 34. Therefore, the LEDs 15-1 to 15-n and the LED 35 -1 to 35-m are connected in parallel and turned on.

  That is, in the fourth embodiment, when the capacitor 20 is charged, the constant current circuit 34 and the LED block 35, the constant current circuit 14 and the LED block, and the capacitor 20 are connected in series to charge the capacitor 20, and the pulsating voltage Accordingly, the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on. When the capacitor 20 is discharged, the constant current circuit 34 and the LED block 35, the constant current circuit 14 and the LED block 15, and the capacitor 20 are connected in parallel, and the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m. Lights up. In such 4th Embodiment, since both LED15-1 to 15-n and LED35-1 to 35-m can be lighted at the time of discharge, lighting efficiency can be improved.

(E) 5th Embodiment FIG. 12: is a figure which shows the structural example of the LED drive device which concerns on 5th Embodiment of this invention. In FIG. 12, portions corresponding to those in FIG. 1 are denoted by the same reference numerals and description thereof is omitted. As shown in FIG. 12, in the LED drive device 10D according to the fifth embodiment, the capacitor 20 is replaced with capacitors 80 to 82 and diodes 83 to 88 are added as compared with the case of FIG. Further, a transistor 90, resistors 91 and 92, and a Zener diode 93 are added. The capacitors 80 to 82 are capacitors having the same breakdown voltage and capacitance, and for example, the breakdown voltage is 100 V and the capacitance is 22 μF.

  Here, the capacitors 80 to 82 and the diodes 83 to 88 operate so that the three capacitors 80 to 82 are connected in series at the time of charging, and the capacitors 80 to 82 are connected in parallel to be discharged at the time of discharging. .

  The transistor 90 is turned off when the pulsating voltage is less than or equal to the chargeable voltage of the capacitors 80 to 82, and is turned on in the other cases so that the resistors 91 and 92 and the Zener diode 93 are turned on. The element value is set. In the fifth embodiment, n = 20 and 200 V is applied as the power supply voltage.

  Next, the operation of the fifth embodiment will be described. Hereinafter, the respective voltages of the capacitors 80 to 82 are assumed to be Vc1 to Vc3, and the sum of the forward drop voltages of the LEDs 15-1 to 15-n is assumed to be VF. In addition, for example, the transistor 90 is set to be in an on state when the pulsating voltage becomes VF × 4-10 (V) or more, and is set to be in an off state when the voltage is less than that. In such a state, when the pulsating voltage rises and becomes equal to or higher than Vc1 + Vc2 + Vc3 + VF, the voltage VF is applied to the LED block 15, so that a current is passed through the LEDs 15-1 to 15-n and lights up. At this time, since the transistor 90 is in an on state (since the pulsating voltage is VF × 4-10 (V) or more), the current output from the constant current circuit 14 is the LED block 15, the diode 17, the capacitor 80, the diode 84, the capacitor 81, the diode 87, the capacitor 82, the diode 22, and the transistor 90 and the anode of the diodes 13 c and 13 d. As a result, the LEDs 15-1 to 15-n are turned on and the capacitors 80 to 82 are charged.

  When the pulsating voltage starts to decrease and becomes less than VF × 4−10 (V), the transistor 90 is turned off. When the transistor 90 is turned off, no current flows to the diode 22, so that the transistor 21 is turned on. When the transistor 21 is turned on, the capacitors 80 to 82 are connected in parallel to the constant current circuit 14 and the LED block 15. More specifically, the capacitor 80 has an upper terminal (plus side terminal) connected to the input side of the constant current circuit 14 via the diode 16, and a lower side terminal (minus side terminal) that connects the transistor 21 and the diode 83. To the cathode terminal of the LED 15-n. The capacitor 81 has an upper terminal (plus side terminal) connected to the input side of the constant current circuit 14 via the diode 85 and a lower side terminal (minus side terminal) via the transistor 21 and the diode 86 to the LED 15 -n. Connected to the cathode terminal. The capacitor 82 has an upper terminal (positive terminal) connected to the input side of the constant current circuit 14 via a diode 88 and a lower terminal (negative terminal) connected to the cathode terminal of the LED 15-n via the transistor 21. Connected to. As a result, the LEDs 15-1 to 15-n are turned on by the electric charges accumulated in the three capacitors 80 to 82 connected in parallel. Even when the voltages of the capacitors 80 to 82 are not uniform, the voltages are equalized in the state of being connected in parallel and are connected in parallel to the LED block 15, so that Vc1 = Vc2 = Vc3≈VF. Become.

  FIG. 13 is a diagram for explaining the operation of the fifth embodiment. As shown in this figure, in the fifth embodiment, capacitors 80 to 82 connected in series with a voltage of 4 × VF (V) are charged during charging, and capacitors connected in parallel with a voltage of VF (V) during discharging. 80 to 82 are discharged. In the fifth embodiment, the input power conduction angle is about 40 degrees, and the angle at which the 20 LEDs are lit is the remaining angle obtained by subtracting the charging period from the ON period of the transistor 90. That is, as shown in FIG. 13, in the fifth embodiment, since the LEDs are lit except for the period τ, the angle obtained by subtracting the 2 × τ period from the entire section is the angle at which 20 LEDs are lit. .

  As described above, according to the fifth embodiment, since the three capacitors 80 to 82 are connected in series to share the voltage, the power supply voltage is considerably higher than the total forward voltage drop VF of the LEDs. Even when the voltage is low (in the fifth embodiment, the peak voltage of the pulsating voltage is about 282 V with respect to VF = 64 V), the power loss in the constant current circuit 14 can be reduced, and the capacitors 80 to 82 are connected. Since discharge is performed in parallel connection, the accumulated charges can be used effectively. In the case where the transistor 90 is provided and the voltage is lowered, the supply of power is cut off, so that the discharge period can be quickly shifted and the accumulated charge can be used effectively. In the above description, the case where the power supply voltage is 200 V has been described as an example, but it goes without saying that the voltage may be 220 V or 240 V or other voltage.

(F) 6th Embodiment FIG. 14: is a figure which shows the structural example of the LED drive device which concerns on 6th Embodiment of this invention. In FIG. 14, parts corresponding to those in FIG. As shown in FIG. 14, the LED drive device 10E according to the sixth embodiment is disconnected from the input of the constant current circuit 14 and the cathodes of the diodes 13a and 13b as compared with the case of FIG. A current circuit 34 and an LED block 35 are inserted. The cathode of the LED 35-m is connected to the emitter of the transistor 14e through the diode 36. Other configurations are the same as those in FIG. In the sixth embodiment, n = 16 and m = 8. Specifically, the LED block 15 is configured by 16 LEDs, and the LED block 35 is configured by 8 LEDs. In the sixth embodiment, 200 V is applied as the power supply voltage.

  Next, the operation of the sixth embodiment will be described. In the following description, the terminal voltages of the capacitors 80 to 82 are Vc1 to Vc3, the sum of the forward drop voltages of the LEDs 15-1 to 15-n is VF1, and the forward drop voltages of the LEDs 35-1 to 35-m. Is the sum of VF2. Further, in the sixth embodiment, for example, the transistor 90 is assumed to be in an off state when the pulsating voltage becomes 4 × VF1 + VF2−10 (V) or less, and is assumed to be in an on state in other cases. .

  When the pulsating voltage rises and becomes Vc1 + Vc2 + Vc3 + VF1 + VF2 or more, the voltages VF1 and VF2 are applied to the LED block 15 and the LED block 35, respectively. As a result, the current output from the constant current circuit 34 is applied to the LED block 35, the diode 36, the LED block 15, the diode 17, the capacitor 80, the diode 84, the capacitor 81, the diode 87, the capacitor 82, the diode 22, and the transistor 90. Via, it flows to the anodes of the diodes 13c and 13d. As a result, the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on, and the capacitors 80 to 82 are charged.

  When the pulsating voltage starts to decrease and the voltage becomes 4 × VF1 + VF2−10 (V) or less, the transistor 90 is turned off and the supply of the pulsating voltage is cut off. When the supply of the pulsating voltage is interrupted, no current flows through the diode 22, so that the transistor 21 is turned on. When the transistor 21 is turned on, the capacitors 80 to 82 are connected in parallel to the constant current circuit 14 and the LED block 15 connected in series according to the same operating principle as in the fifth embodiment. As a result, charges are supplied to the LED block 15 from the three capacitors 80 to 82 connected in parallel, so that the LEDs 15-1 to 15-n are turned on.

  When the pulsating voltage starts to rise again and the voltage becomes 4 × VF1 + VF2−10 (V) or more, the transistor 90 is turned on and supply of the pulsating voltage is started. When the pulsating voltage becomes Vc1 + Vc2 + Vc3 + VF1 + VF2, the LEDs 15-1 to 15-n and the LEDs 35-1 to 35-m are turned on, and the capacitors 80 to 82 are connected in series and charged.

  As a result, during the charging period of the capacitors 80 to 82, the capacitors 80 to 82, the LED block 15, and the LED block 35 are connected in series to charge the capacitors 80 to 82, and the LEDs 15-1 to 15-n, The LEDs 35-1 to 35-m are turned on. In the discharging period, capacitors 80 to 82 are connected in parallel, connected to the constant current circuit 14 and the LED block 15 connected in series, and the LEDs 15-1 to 15-n are turned on.

  By repeating the above operation, the capacitors 80 to 82 are connected in parallel during the discharge period, so that the terminal voltage variation between the capacitors is made uniform and the capacitor 80 is connected to the LED block 15. Vc1 to Vc3, which are terminal voltages of ˜82, are close to VF1.

  As described above, according to the sixth embodiment of the present invention, the efficiency can be adjusted by adjusting the number of divisions of the LEDs, and the capacitors 80 to 82 are connected in series. Power loss in the constant current circuit 34 can be reduced. Further, since the supply of the pulsating voltage is cut off immediately after the end of the charging period by the transistor 90, the discharging period can be extended to increase the efficiency. In the above description, the case where the power supply voltage is 200 V has been described as an example, but it goes without saying that the voltage may be 220 V or 240 V or other voltage.

(G) Modified Embodiment The above-described embodiment is an example, and it goes without saying that there are various modified embodiments. For example, the number of LEDs in each of the above embodiments is an example, and it goes without saying that other numbers may be used. In each of the above embodiments, the circuit is configured using an analog circuit. However, the present invention is not limited to such a case. For example, the circuit may be configured using a digital circuit. It is. In that case, in the circuit shown in FIG. 1, the control circuit 6 can be realized by a central processing unit such as a CPU.

  In each of the above embodiments, an NPN bipolar transistor is used as an active element. However, for example, a PNP bipolar transistor may be used. Alternatively, other elements such as an FET element or a three-terminal regulator can be used. Further, although an N channel MOS-FET is used as a switching element, a P channel MOS-FET may be used. In each of the above embodiments, the capacitor has been described by taking a 22 μF capacitor having a withstand voltage of 100 V as an example, but it goes without saying that a capacitor having a withstand voltage and a capacity other than this may be used.

  In the third and sixth embodiments, some LED units are connected in parallel at the time of discharging, but not all LED units may be connected in parallel to the capacitor. .

  In addition, although the embodiments in which the plurality of capacitors 80 to 82 are in a series state when charging and in a parallel state when discharging are shown as the fifth and sixth embodiments, such a configuration is, for example, the first to the first It is also possible to add to the four embodiments. In this case, the number of capacitors to be used is not limited to three, and an appropriate number of capacitors may be selected according to the relationship between the power supply voltage and VF.

  Moreover, although embodiment which interrupts | blocks supply of a pulsating voltage according to a pulsating voltage was shown as 5th and 6th embodiment, such a structure can also be added to 1st-4th embodiment, for example. Is possible.

  In the above embodiment, the commercial power supply is used after full-wave rectification, but may be used after half-wave rectification.

  In each of the above embodiments, only the LED driving device has been described. For example, by incorporating the LED driving device shown in each of the above embodiments in a lighting device having a light bulb shape, efficient LED lighting is possible. An apparatus can be realized. Note that the LED lighting device is not limited to a light bulb shape, and may have other shapes.

1, 10A, 10B, 10C, 10D, 10E LED driving device 2 terminal 3 rectifier circuit 4 constant current circuit 5-1 to 5-n LED
6 Control circuit 7 Capacitor 8 LED block 11, 12 Power supply terminal 13a-13d Diode 14, 34, 44 Constant current circuit 15, 35 LED block (LED group)
16, 17 Diode 18, 19 Resistor 20 Capacitor 21 Transistor 22 Diode 45, 50 Charge circuit 80-82 Capacitor 63, 65, 90 Transistor

Claims (5)

In an LED driving device that lights an LED with a pulsating voltage obtained by rectifying an AC voltage with a rectifier circuit,
A plurality of LED units each having an LED group composed of a plurality of LEDs connected in series, and a constant current circuit connected in series to the LED group;
A plurality of LED units are connected in series, capacitors are connected in series to the LED units, a first connection state in which the pulsating current is applied to the LED units and the capacitors to charge the capacitors, and the charged A control circuit for controlling the switching between a second connection state in which a capacitor is connected in parallel to some LED units of the plurality of LED units and the electric charge stored in the capacitor is discharged through the LED units. And an LED driving device. 2. The LED driving device according to claim 1, wherein the control circuit connects the capacitor in parallel to the partial LED unit when the pulsating voltage becomes lower than a terminal voltage of the capacitor. A plurality of said capacitor, charging of these capacitors connected in series said plurality of capacitors, during discharging LED driving device according to claim 1 or 2, characterized in that connected in parallel said plurality of capacitors . When charging the capacitor, if the pulsating voltage becomes equal to or lower than a predetermined voltage, the pulsating voltage is cut off and forcedly shifted from the first connection state to the second connection state. The LED driving device according to claim 3 , further comprising a cutoff circuit . An LED lighting device, wherein the LED is turned on using the LED driving device according to claim 1 .

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