KR102130176B1 - Power supply circuit for alteration of flicker frequency of light emitting diode - Google Patents

Abstract

The present invention relates to a power supply circuit. More specifically, it relates to a power supply circuit capable of increasing the flashing frequency of a light emitting diode by using a charge/discharge circuit and a switch installed between an AC voltage source and a load. The power supply circuit according to the invention is connected to an AC voltage source, and a rectifying circuit for full-wave rectifying the AC voltage of the AC voltage source, one end connected to the output side and the light emitting diode array of the rectifying circuit, the other end connected to ground, and the rectification Charged and discharged by a voltage output from the circuit and configured to supply power to the light-emitting diode array, a first switch installed in a path connecting the charge-discharge circuit and the light-emitting diode array, and output from the rectifying circuit And a controller configured to control the first switch such that the charge/discharge circuit is discharged in the section A where the magnitude of the voltage is less than the driving voltage of the LED array so that the LED array flashes at least once in the section A. . The power supply circuit according to the present invention uses a charge/discharge circuit and a switch, and the magnitude of the voltage applied by the AC voltage source is equal to or less than the driving voltage, and a high pulse form with a driving voltage higher than the driving voltage in an area around 180 degrees where the LED cannot be driven. Voltage can be applied. Through this, the flashing frequency of the light-emitting diode can be increased to 240 Hz or more (for 60 Hz AC power).

Description

POWER SUPPLY CIRCUIT FOR ALTERATION OF FLICKER FREQUENCY OF LIGHT EMITTING DIODE

The present invention relates to a power supply circuit. More specifically, it relates to a power supply circuit capable of increasing the flashing frequency of a light emitting diode by using a charge/discharge circuit and a switch installed between an AC voltage source and a load.

Since light emitting diodes (LEDs) have advantages in terms of light efficiency and durability, they are spotlighted as light sources for backlights of lighting devices and display devices.

The light emitting diode is driven at a low direct current. Therefore, conventionally, a power supply device for changing a commercial AC voltage (AC 220 volt) to a DC voltage was used. For example, SMPS (Switched-Mode Power Supply), linear power, and the like were used. However, the conversion efficiency of such a power supply is generally low. In addition, since the life of the electrolytic capacitor among the used parts is short, the use of such a power supply device has a problem of shortening the life of the light emitting diode lighting device.

To solve this problem, a method has been developed in which two strings of light-emitting diodes are directly connected to an AC power source in the forward and reverse directions without converting to DC. However, this method has a problem in that efficiency is low because only 50% or less of the connected light emitting diodes are turned on. In addition, as the magnitude of the input voltage changes, the current flowing through the light-emitting diode changes rapidly, which may adversely affect the light-emitting diode device, and there is a problem that the change in brightness is also large. In addition, since the current flows in the circuit only when the magnitude of the input voltage is greater than or equal to a value capable of operating all of the light-emitting diodes included in the light-emitting diode string, the difference between the waveform of the alternating current and the waveform of the alternating voltage is large. This lowers the problem.

In order to solve the problem of the method of directly using the AC power, various methods have been developed to use AC after rectifying it through a bridge circuit. For example, Korean Patent Publication No. 10-2012-0041093 discloses a method of adjusting the number of light-emitting diodes to which a rectified voltage is applied according to a change in magnitude of the rectified voltage after rectifying the AC voltage. This method has an advantage that the number of light-emitting diodes operating is higher than the method of directly using an AC power source, and thus the efficiency is high, and the power supply time is fast, so that the power factor is improved.

The problem of the method of using the AC power after rectifying using a bridge circuit is to drive the light emitting diode using a full-wave rectified wave having a frequency of 120 Hz, so that the size of the AC power emits light in a significant area around 180 degrees of phase. That is, it is smaller than the driving voltage of the diode, so that no lighting occurs.

The human eye feels continuously, not intermittently blinking, in the case of a light source flickering above the flicker fusion frequency. Therefore, it is felt that the light-emitting diode blinking at a frequency higher than the flashing fusion frequency remains on in the human eye. Most human eyes feel that the light source blinking above 75㎐ is continuous. However, in the case of a person who is sensitive to light, it is also possible to feel the flicker of the light-emitting diode blinking at 120 Hz, and it is preferable to blink at a high frequency if possible because it may cause a seizure.

Therefore, in Japan, there is no flicker phenomenon between 100㎐ and 500㎐ in the lighting certification standard, and European countries are also trying to stipulate to drive lighting at frequencies above 150㎐. The U.S. recently established an Energy Star certification rule, so that if the level of flicker does not exceed a certain standard, it will not be included in the certification. Accordingly, a situation may arise in which light emitting diode lights driven by using the full-wave rectifying wave are fundamentally impossible to sell.

To improve this, Korean Patent Publication No. 10-2010-0104362 discloses a method using a valley fill circuit. Although this method can be expected to improve the flicker phenomenon, a capacitor having a large capacity should be used, and a side effect of deteriorating power factor may occur due to the mounting of the capacitor. In addition, when the input voltage decreases, a flicker of 120 kHz is displayed. Additionally, by separately operating a plurality of groups of light-emitting diodes connected in parallel, the number of light-emitting diodes required increases, leading to an increase in cost and an unlit array.

As another improvement method, a charge/discharge circuit as disclosed in Korean Patent Publication No. 10-2012-0082468 can be used. Even in this case, the flicker phenomenon is improved, but it does not exceed the limit of flicker of 120 Hz. In addition, when the input voltage falls, sufficient charging is not achieved and the start time of discharge is shortened, so that the flicker phenomenon becomes more prominent.

Another problem of the method of using the AC power after rectifying using a bridge circuit is that when the driving voltage is set high, the phase region in which the light emitting diode is lit is small, so the efficiency of using the light emitting diode (effective power consumption of the light emitting diode/DC rating) When the current is driven, the light emitting diode power consumption) and the power factor are lowered, and when the driving voltage is set low, a significant portion of the power is consumed as heat and power efficiency is reduced.

As a method of driving a light-emitting diode using an AC power, a method using triac in dimming control is proposed in Korean Patent Publication No. 10-2011-0091444, but there is a problem that it cannot function as a lighting as the unlit section is longer. .

Korean Registered Patent 10-0971757 Korea Patent Publication 10-2012-0041093 Korea Patent Publication 10-2010-0104362 Korea Patent Publication 10-2012-0082468 Korea Patent Publication 10-2011-0091444

The present invention is to improve the above-described problem, and by applying a high voltage in the form of a pulse higher than the driving voltage to the area around the phase 180 using a charge/discharge circuit and a switch, a power supply capable of increasing the flashing frequency of the light emitting diode It is an object to provide a circuit.

In addition, an object of the present invention is to provide a power supply circuit that increases the efficiency of light-emitting diodes by increasing the power supply efficiency by setting a high driving voltage, and improves the use efficiency of the light-emitting diodes because the phase region in which the light-emitting diodes are lit is wide.

The power supply circuit according to the present invention for solving the above-described problem is connected to an AC voltage source, and a rectifying circuit for full-wave rectifying the AC voltage of the AC voltage source, and one end is connected to the output side and the light emitting diode array of the rectifying circuit, the other end Is connected to the ground, and is charged by a voltage output from the rectifying circuit, and a charging/discharging circuit configured to supply power to the light emitting diode array, and a first switch installed in a path connecting the charging/discharging circuit and the light emitting diode array. In addition, the first switch is controlled so that the charge/discharge circuit is discharged in section A in which the magnitude of the voltage output from the rectifying circuit is less than the driving voltage of the light emitting diode array so that the light emitting diode array flashes at least once in section A. It may include a controller configured to.

By flashing the LED array in section A, it is possible to increase the flashing frequency of the LED array and increase the efficiency of using the LED.

The above-described power supply circuit may further include a second switch installed in a path connecting the output side of the rectifying circuit and the charging/discharging circuit, and the controller controls a charging start time and a charging end time of the charging/discharging circuit. In order to do this, the second switch can be controlled.

In addition, a third switch installed between the output side of the rectifying circuit and the light emitting diode array may be further included, and the controller may blink the light emitting diode array at least once in section B within a driving voltage range of the light emitting diode array. The third switch can be controlled.

In addition, in order to reduce the total high-frequency distortion (THD) of the current waveform flowing through the light-emitting diode array, a current limiting circuit configured to limit the current flowing through the charge/discharge circuit may be further included.

Further, in order to improve the power factor, a charging circuit configured to be connected to and charged with the output side of the rectifying circuit in the section A may be further included.

According to another embodiment of the power supply circuit according to the present invention, by connecting to an AC voltage source, the rectifying circuit for full-wave rectifying the AC voltage of the AC voltage source, one end is connected to the output side and the light emitting diode array of the rectifying circuit, the other end A charging/discharging circuit connected to ground, charged by a voltage output from the rectifying circuit, and configured to supply power to the light-emitting diode array, connected in series with the charging/discharging circuit, and connecting the charging/discharging circuit to the rectifying circuit. The fourth switch connects or disconnects the output side and the light emitting diode array, and the fourth switch so that the charging and discharging circuit is charged in section B in which the magnitude of the voltage output from the rectifying circuit is within the driving voltage range of the light emitting diode array. The fourth switch is controlled so that the charge/discharge circuit is discharged in the section A where the magnitude of the voltage output from the rectifying circuit is less than the driving voltage of the LED array so that the LED array flashes at least once in the section A. A power supply circuit is provided that includes a controller configured to control.

In addition, further comprising a third switch installed between the output side of the rectifying circuit and the light emitting diode array, the controller blinks the light emitting diode controlling the third switch so that the light emitting diode array flashes at least once in the B section. A power supply circuit for converting frequencies is provided. The controller may control the fourth switch so that the charging and discharging circuit is charged when the third switch is off.

According to another embodiment of the power supply circuit according to the present invention, the rectifying circuit is connected to an AC voltage source to rectify the AC voltage of the AC voltage source, and is connected in series with the rectifying circuit and the light emitting diode array, and the rectifying circuit Charged and discharged by a voltage output from and configured to supply power to the light-emitting diode array, a fifth switch installed in a path for bypassing the charge-discharge circuit, and installed in a path for bypassing the light-emitting diode array The sixth switch, the seventh switch installed in a path connecting the charge/discharge circuit and the light-emitting diode array in series, and the rectification in section B where the magnitude of the voltage output from the rectification circuit is within the driving voltage range of the light-emitting diode array The fifth switch is turned on, the seventh switch is turned off so that the voltage at the output terminal of the circuit is directly applied to the LED array, and the magnitude of the voltage output from the rectifying circuit exceeds the driving voltage of the LED array. In the section, the fifth switch is turned off, the seventh switch is turned on, and the magnitude of the voltage output from the rectifying circuit is such that the voltage at the output terminal of the rectifying circuit is distributed and applied to the light emitting diode array and the charging/discharging circuit. The charging and discharging circuit is discharged in section A below the driving voltage of the light emitting diode array, so that the fifth switch is turned on so that the light emitting diode array flashes at least once in the section A, and the sixth switch is turned on/off. A power supply circuit is provided that includes a controller configured to control the fifth switch, the sixth switch, and the seventh switch.

In addition, the charging and discharging circuit is a charging pump including a switching device configured to connect a plurality of capacitors and a plurality of capacitors in parallel or in series, and the controller when the charging and discharging circuit is discharged in the section A, the plurality of A power supply circuit is provided to control the switching device so that its capacitors are connected in series.

The power supply circuit according to the present invention uses a charge/discharge circuit and a switch, and the magnitude of the voltage applied by the AC voltage source is equal to or less than the driving voltage, and a high pulse form with a driving voltage higher than the driving voltage in an area around 180 degrees where the LED cannot be driven. Voltage can be applied. Through this, the flashing frequency of the light-emitting diode can be increased to 240 Hz or more (for 60 Hz AC power). Since the light-emitting diode is blinked by a pulse voltage in a region around 180 degrees out of phase where the light-emitting diode is extinguished, the flashing frequency of the light-emitting diode is doubled. Through this, the flicker phenomenon can be improved.

In addition, when the driving voltage is set high, the problem that the light emitting diode is not driven in a significant region around the phase 180 degrees is solved by applying a high pulse type voltage higher than the driving voltage around 180 degrees, thereby providing power efficiency and light emitting diode. The utilization efficiency is improved at the same time.

In addition, in some embodiments, a high voltage higher than the driving voltage may be applied to the light emitting diode in the form of a pulse having a higher frequency through switching.

1 is a view schematically showing an embodiment of a power supply circuit according to the present invention.
FIG. 2 is a block diagram of the controller shown in FIG. 1.
3 is a diagram showing an example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 1.
4 is a diagram showing another example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 1.
5 is a view showing another example of a voltage waveform input to the light emitting diode array in the power supply circuit shown in FIG. 1.
6 is a view schematically showing another embodiment of a power supply circuit according to the present invention.
7 is a view schematically showing another embodiment of a power supply circuit according to the present invention.
8 is a diagram illustrating an example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 7.
9 is a view schematically showing another embodiment of a power supply circuit according to the present invention.
10 is a diagram showing an example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 9.

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

In the following, the embodiments introduced below are provided as examples in order to sufficiently convey the spirit of the present invention to those skilled in the art. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms.

1 is a view schematically showing an embodiment of a power supply circuit according to the present invention.

Referring to FIG. 1, an embodiment of a power supply circuit according to the present invention includes a first switch 11, a second switch 12, a third switch 13, a controller 20, and a charge/discharge circuit 30 , It includes a rectifying circuit (3) and a current or voltage limiting circuit (4).

One embodiment of the power supply circuit according to the present invention effectively controls the charging and discharging time of the charging/discharging circuit 30 connected to the rectifying circuit 3, so that the magnitude of the voltage output from the rectifying circuit 3 is the load. The LED array 2 can be operated even when the driving voltage is lower than or equal to the driving voltage. Through this, the flashing frequency of the light-emitting diode array 2 is increased, and the light-emitting diode utilization efficiency (light-emitting diode effective power consumption/light-emitting diode power consumption when driving the DC rated current) is increased.

The rectifying circuit 3 serves to fully rectify the AC voltage input. The rectifying circuit 3 may be a bridge diode circuit. The rectifying circuit 3 may be installed between the AC voltage source 1 and the charge/discharge circuit 30 as shown in FIG. 1.

The switches 11, 12, and 13 may be configured with a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) switch or the like. The first switch 11 installed in the path connecting the charge/discharge circuit 30 and the light emitting diode array 2 and the second installed in the path connecting the output terminal of the rectifying circuit 3 and the charge/discharge circuit 30 The switch 12 is used to adjust the discharge time and charge time of the charge/discharge circuit 30. By adjusting the charging point and the discharging point, the LED array 2 is flashed in a region where the voltage output from the rectifying circuit 3 is equal to or less than the driving voltage of the LED array 2.

When the second switch 12 is turned on, charging occurs in the charging/discharging circuit 30 while the output terminal of the rectifying circuit 3 is connected to the charging/discharging circuit 3, and when the first switch 11 is turned on, the charging/discharging circuit ( 3) and the light emitting diode array 2 are connected, and discharge occurs in the charging/discharging circuit 30 to supply power to the light emitting diode array 2.

The third switch 13 installed in the path connecting the output terminal of the rectifying circuit 3 and the light-emitting diode array 2 in series determines when the voltage output from the rectifying circuit 3 is applied to the light-emitting diode array 2. Adjust. When the third switch 13 is turned off, voltage is not applied to the light emitting diode array 2. The third switch 13 serves to change the flashing frequency of the light emitting diode array 2.

The controller 20 checks the magnitude or phase of the voltage output from the rectifying circuit 3 and controls the first switch 11 and the second switch 12 to control the discharge time and the charging time.

In addition, the controller 20 controls the on/off time of the third switch 13. When the magnitude of the voltage output from the rectifying circuit 3 is greater than or equal to the driving voltage of the light emitting diode array 2, the third switch 13 may remain on or repeat on/off.

When the on/off is repeated, the light emitting diode array 2 is driven by the pulse voltage, and the shape of the pulse voltage is determined by adjusting the time that the third switch 13 is turned on and off.

FIG. 2 is a block diagram of the controller shown in FIG. 1. Referring to FIG. 2, the controller 20 includes a memory 21, a voltage or phase detection circuit 22, and a switch control unit 23. The voltage detection circuit checks in which range the instantaneous value of the voltage output from the rectifying circuit 3 belongs. As the voltage detection circuit, various circuits widely used in the field of electronic circuits can be used. For example, a voltage comparator using a plurality of OP amplifiers can be used. A phase detection circuit can be used for the controller 20 instead of a voltage detection circuit that directly detects the voltage. The phase detection circuit can be configured by using a zero cross detector or the like capable of detecting the moment when the instantaneous value of the voltage becomes zero. Since the instantaneous value of the voltage output from the rectifying circuit 3 varies depending on the phase, the change in the instantaneous value can be seen through the change in phase.

In the memory 21, driving data for driving the switches 11, 12 and 13 according to the magnitude of the voltage output from the rectifying circuit 3 is stored. The driving data is determined according to the number and driving voltage of the light-emitting diodes, the flashing frequency of the required light-emitting diode array, and the like.

The switches 11, 12, and 13 may be controlled according to the voltage or phase detected for each channel without using a memory, or by using a counter element such as a timer.

The charge/discharge circuit 30 is charged by the output voltage of the rectifying circuit 3 and then discharged in a section in which the magnitude of the voltage output from the rectifying circuit 3 is less than the driving voltage of the light emitting diode array 2, and the light emitting diode array (2) It plays a role of applying power to. In this embodiment, a capacitor is used as an example of the charge/discharge circuit 30. When the second switch 12 is turned on, the charging/discharging circuit 30 is connected to the rectifying circuit 3 to store electrical energy in the charging/discharging circuit 30. When the first switch 11 is turned on, the charge/discharge circuit 30 is connected to the light emitting diode array 2 and discharge occurs in the charge/discharge circuit 30 to supply power to the light emitting diode array 2. An inductor may be used as the charge/discharge circuit 30.

The current limiting circuit or voltage limiting circuit 7 serves to limit the current or voltage applied to the load. The current limiting circuit or the voltage limiting circuit is for preventing excessive current from flowing through the light emitting diode array 2, and is connected in series to the light emitting diode array 2. The current limiting circuit can be implemented with a resistor, a capacitor, a bipolar transistor, or a Morse transistor. In addition, it can be implemented by a method of implementing a combination of a field effect transistor (FET) or a transistor (TR) and an auxiliary device, and a method using an integrated circuit such as an OP AMP or a regulator.

In addition, between the power supply circuit and the AC voltage source 1, a surge protection circuit comprising a resistor 6, a surge suppression element (not shown), a fuse 5, etc. for protecting the power supply circuit from surge voltages may be further included. Can.

In addition, it is preferable to further include a current limiting circuit 9 arranged in series with the second switch 12, for example, as shown in FIG. 1, between the second switch 12 and the ground. . In the present embodiment, when the second switch 12 is turned on, current flows toward the charge/discharge circuit 30, and harmonic components are generated in the current waveform flowing through the light emitting diode array 2. Using the current limiting circuit 9 to limit the current flowing to the charge/discharge circuit 30 during charging, the total harmonic distortion (THD) can be reduced.

In addition, although not shown, in order to improve the power factor by minimizing the difference between the current waveform and the voltage waveform below the driving voltage of the light emitting diode array 2, a charging circuit configured to be charged below the driving voltage may be further included. This charging circuit can be used for the purpose of supplying the driving power of the switches 11, 12, and 13.

3 is a diagram showing an example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 1. Referring to Fig. 3, the operation of the power supply circuit will be described.

As a result of measuring the magnitude of the voltage output from the rectifier circuit 3 by the controller 20, when it is determined that the controller 20 belongs to the area A below the driving voltage, the second switch 12 and the third switch 13 are turned on. , The first switch 11 is turned off (because the charge/discharge circuit is not charged yet, the first switch 11 is turned off). The third switch 13 is turned on, but since the voltage of the input source is less than the driving voltage, the light emitting diode array 2 is not turned on.

Since the second switch 12 is turned on, the charge/discharge circuit 30 is charged. However, since the voltage is low, electric energy is not stored enough to operate the light emitting diode array 2.

In the area A, the third switch 13 may be turned off to prevent the voltage output from the rectifying circuit 3 from being input to the light emitting diode array 2. This is because the light emitting diode does not operate in this section, and only heat is generated.

As a result of measuring the magnitude of the voltage output from the rectifying circuit 3 by the controller 20, when the region B of the driving voltage is reached, since the voltage of the input source is greater than or equal to the driving voltage, the light emitting diode array 2 is turned on. Since the second switch 12 is turned on, electrical energy is continuously charged to the capacitor that is the charge/discharge circuit 30. When charging is completed, the second switch 12 may be turned off, but as shown in FIG. 3, it may be turned on continuously.

As a result of measuring the magnitude of the voltage output from the rectifying circuit 3 by the controller 20, when it is determined that the area A has been reached again, electricity is charged in the capacitor by turning on the first switch 11 after a certain time has elapsed. Energy is supplied to the light-emitting diode array 2 to turn on the light-emitting diode array 2. After the discharge starts, the first switch 11 is turned off at a certain point in time to turn off the light emitting diode array 2 again. That is, the light emitting diode in the area A is blinking once. At this time, the timing of starting and stopping the discharge is determined in conjunction with variables such as the net voltage of the light-emitting diode, the charging capacity, the voltage fluctuation of the input source, and the set driving frequency.

In this embodiment, the light emitting diode array 2 is turned on while entering from area A to area B, and is turned off when it reaches area A, and lights up again when the voltage due to the discharge of the charge/discharge circuit 30 is applied to area A It turns off when the discharge stops. That is, if driven by the 60 ㎐ AC voltage source 1, the flashing frequency of the light emitting diode array 2 increases to 240 kHz.

As described above, the current waveform as shown in FIG. 3 can be obtained even when the second switch 12 and the third switch 13 are continuously turned on. Therefore, in the embodiment illustrated in FIG. 1, the second switch 12 and the third switch 13 may be removed. That is, the second switch 12 can be removed when it is not necessary to adjust the charging start time and the charging end time, and the third switch 13 can be removed when a flashing frequency of 240 Hz or more is not required. .

4 is a diagram showing another example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 1. In this example, the light emitting diode array 2 flashes in the region B, so that the flashing frequency of the light emitting diode array 2 is increased to 240 Hz or more.

As a result of measuring the magnitude of the voltage output from the rectifying circuit 3 by the controller 20, when it is determined that the controller 20 belongs to the area A below the driving voltage, the third switch 13 is turned on and the first switch 11 And the second switch 12 are turned off.

As a result of measuring the magnitude of the voltage output from the rectifying circuit 3 by the controller 20, even when it is determined that the driving voltage range has reached the B region, except for the section in which the light emitting diode array 2 is turned off. The third switch 13 remains on. When the period in which the light emitting diode array 2 is to be turned off in the B area is reached, the third switch 13 is turned off, and then turned on again after a certain period of time. When blinking once in section B, as shown in FIG. 4, the blinking frequency increases to 360 Hz.

If it is necessary to further increase the flashing frequency, as shown in FIG. 5, the number of flashings in section B may be increased. At this time, if the time when the third switch 13 is turned on/off, the duty cycle and frequency can also be adjusted. It is preferable to adjust the time when the third switch 13 is turned on/off so that the average power applied to the load is constant. In the region where the voltage is small, when the on time of the third switch 13 is increased, and when the voltage is large, when the on time of the third switch 13 is shortened, the average power applied to the load is constant. can do.

As shown in FIG. 4, the second switch 12 is turned on in a period in which the third switch 13 is turned off by synchronizing with the third switch 13, or turned off when the third switch 13 is turned on. , It can be turned on/off regardless of the third switch 13. As shown in FIG. 5, after charging is turned on in a part of section B, it may be turned off when charging is completed.

Then, when it is determined that the magnitude of the voltage output from the rectifying circuit 3 has reached the area A again, the electrical energy charged in the capacitor is turned on by turning on the first switch 11 after a certain time has elapsed. ). After the discharge starts, the first switch 11 is turned off at a certain point in time to turn off the light emitting diode array 2 again. The time point for starting and stopping the discharge can be appropriately selected within the area A.

6 is a view schematically showing another embodiment of a power supply circuit according to the present invention.

In this embodiment, an inductor is used instead of a capacitor, and a separate resistor 7 is installed between the AC voltage source 1 and the load and between the AC voltage source 1 and the inductor of the charge/discharge circuit 30. There is a difference. In this embodiment, a capacitor can be used as the charge/discharge circuit 30 instead of the inductor.

7 is a view schematically showing another embodiment of a power supply circuit according to the present invention.

In the case of this embodiment, instead of the first switch 11 and the second switch 12, a fourth switch 14 is provided between the charge/discharge circuit 30 and the ground. When the fourth switch 14 is turned on, charging proceeds, and when it is turned off, charging is stopped. And when the fourth switch 14 is turned on again in the state of being charged, discharge proceeds, and when it is turned off, discharge is stopped.

8 is a diagram illustrating an example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 7. The operation of this embodiment will be described with reference to FIG. 8.

As a result of measuring the magnitude of the voltage output from the rectifier circuit 3 by the controller 20, when it is determined that the controller 20 belongs to an area below the driving voltage, the third switch 13 is turned on, and the fourth switch 14 is turned on. Off. The third switch 13 is turned on, but since the voltage of the input source is less than the driving voltage, the light emitting diode array 2 is not turned on.

As a result of measuring the magnitude of the voltage output from the rectifying circuit 3 by the controller 20, even when it is determined that the driving voltage range has reached the B region, except for the section in which the light emitting diode array 2 is turned off. The third switch 13 remains on. When the period in which the light emitting diode array 2 is to be turned off in the B area is reached, the third switch 13 is turned off, and then turned on again after a certain period of time. When flashing once in section B, as shown in FIG. 8, the flashing frequency increases to 360 Hz.

In section B, the fourth switch 14 is synchronized with the third switch 13 to be turned on in a period in which the third switch 13 is turned off, and turned off when the third switch 13 is turned on, or the third switch ( It can be turned on/off regardless of 13).

In addition, when it is determined that the magnitude of the voltage output from the rectifying circuit 3 belongs to the region A again, the electric energy charged in the capacitor is turned on by turning on the fourth switch 14 after a certain time has elapsed. To be supplied. After the discharge starts, the fourth switch 14 is turned off at a certain time to turn off the light emitting diode array 2 again. The time point for starting and stopping the discharge can be appropriately selected within the area A.

When the on/off of the third switch 13 is repeated in section B, a pulse-type current as shown in FIG. 5 is input to the light emitting diode array 2.

9 is a view schematically showing another embodiment of a power supply circuit according to the present invention. In the present embodiment, the AC voltage source 1 and the AC voltage source 1 are rectified circuits 3 for full-wave rectification, and charge/discharge circuits 35 and light-emitting diodes sequentially connected in series with the output side of the rectification circuit 3 It includes an array 2 and a current limiting circuit 4.

Then, the charge/discharge circuit 35 is bypassed to bypass and charge/discharge the fifth switch 15 and the light-emitting diode array 2 installed on a conductor connecting the rectifying circuit 3 and the light-emitting diode array 2 in series. Includes a sixth switch (16) installed on a conductor connecting the circuit (35) and a current limiting circuit (4) in series, and a seventh switch (17) installed between the charge/discharge circuit (35) and the light emitting diode array (2). do. The fifth switch 15, the sixth switch 16 and the seventh switch 17 are operated by the control signal of the controller 20.

FIG. 10 is a diagram showing an example of a voltage waveform of an input source and a current waveform input to a light emitting diode array in the power supply circuit shown in FIG. 9. When the magnitude of the full-wave rectified voltage output from the rectifying circuit 3 falls within the A region, the fifth switch 15 is turned on, and the sixth switch 16 and seventh switch 17 are turned off. Although the fifth switch 15 is turned on, since a voltage lower than the driving voltage of the light emitting diode array 2 is applied to the light emitting diode array 2, the light emitting diode array 2 is not turned on.

When the magnitude of the full-wave rectified voltage reaches region B, the light-emitting diode array 2 is turned on.

When the magnitude of the voltage increases above the driving voltage and reaches the C region, the fifth switch 15 is turned off, the seventh switch 17 is turned on, and the voltage is charged/discharged circuit 35 and the light emitting diode array 2 ). The capacitors connected in parallel of the charge/discharge circuit 35 are charged by the voltage applied by being distributed and the light emitting diode array 2 is continuously lit.

Again, when the magnitude of the voltage reaches area B, the seventh switch 17 is turned off, and the fifth switch 15 is turned on.

Again, when the magnitude of the voltage reaches area A, the sixth switch 16 is turned on after a certain period of time, and electrical energy stored in the charge/discharge circuit 35 is supplied to the light emitting diode array 2. After the discharge starts, the sixth switch 16 is turned off at a certain time to turn off the light emitting diode array 2 again.

If necessary, for example, when the driving voltage is set high and the LED array 2 cannot be driven with one capacitor, the charge/discharge circuit 35 having two or more capacitors connected in parallel is connected to the LED array. When charging in series connection with (2) and discharging in area A, a charge pump that converts the capacitors in series using a separate switching device and connects them in parallel with the light emitting diode array 2 may be used.

It should be understood that the embodiments described above are illustrative in all respects and not restrictive. The scope of the present invention is indicated by the following claims rather than the above detailed description, and it should be interpreted that all changes or modified forms derived from the meaning and scope of the claims and their equivalent concepts are included in the scope of the present invention. do.

1: AC voltage source 2, 8: light emitting diode array
3: Rectifier circuit 11: First switch
12: second switch 13: third switch
14: fourth switch 20: controller
30, 35: charge and discharge circuit

Claims (7)

A rectifying circuit that is connected to an AC voltage source and rectifies the AC voltage of the AC voltage source,
A charging and discharging circuit configured to be charged by the voltage output from the rectifying circuit and to supply power to the light emitting diode array,
A first switch connecting or blocking a path connecting the charge/discharge circuit and the light emitting diode array;
A second switch connecting or blocking a path connecting the output side of the rectifying circuit and the charging/discharging circuit;
The first switch is controlled so that the charge/discharge circuit is discharged in section A in which the magnitude of the voltage output from the rectifying circuit is less than the driving voltage of the light emitting diode array so that the light emitting diode array flashes at least once in section A, and the Power supply for converting the flashing frequency of the light-emitting diode including a controller configured to control the second switch so as to control the charging start time and the charging end time of the charging and discharging circuit according to the change in the magnitude or phase of the voltage output from the rectifying circuit Supply circuit. According to claim 1,
A power source for converting the flashing frequency of the light emitting diode further comprising a current limiting circuit configured to limit the current flowing through the charge/discharge circuit in order to reduce total harmonic distortion (THD) of the current waveform flowing in the light emitting diode array. Supply circuit. According to claim 1,
In order to improve the power factor, the power supply circuit for converting the flashing frequency of the light emitting diode further comprises a charging circuit configured to be connected and charged in the section A to the output side of the rectifying circuit. A rectifying circuit that is connected to an AC voltage source and rectifies the AC voltage of the AC voltage source,
A charging and discharging circuit configured to be charged by the voltage output from the rectifying circuit and to supply power to the light emitting diode array,
A fourth switch connecting or blocking a path connecting the charging/discharging circuit to the output side of the rectifying circuit and the light emitting diode array,
The fourth switch is controlled so that the charge/discharge circuit is discharged in the section A where the magnitude of the voltage output from the rectifying circuit is less than the driving voltage of the LED array, so that the LED array flashes at least once in the section A, Converting the flashing frequency of the light emitting diode including a controller configured to control the fourth switch so that the charging start time and the charging end time are controlled according to the change in the magnitude or phase of the voltage output from the rectifying circuit. Power supply circuit. According to claim 4,
A power source for converting the flashing frequency of the light emitting diode further comprising a current limiting circuit configured to limit the current flowing through the charge/discharge circuit in order to reduce total harmonic distortion (THD) of the current waveform flowing in the light emitting diode array. Supply circuit. According to claim 4,
In order to improve the power factor, the power supply circuit for converting the flashing frequency of the light emitting diode further comprises a charging circuit configured to be connected and charged in the section A to the output side of the rectifying circuit. delete

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