JP2016126918A - Illumination device using led - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination device using LED whose light emission amount is adjustable.SOLUTION: An illumination device using LED has an LED group comprising plural in-series connected LEDs for emitting light on the basis of supplied current for light emission, a current control circuit for receiving an AC voltage from a power source terminal and supplying AC current, and a rectifying circuit for rectifying the AC current from the current control circuit and supplying the rectified AC current to the LED group. The current control circuit has a first capacitor provided between the power source terminal and the rectifying circuit, and a light emission amount adjusting circuit which is provided in parallel to the first capacitor and changes a flowing current value on the basis of an operation. First current flowing in the first capacitor and second current flowing in the light emission amount adjusting circuit are supplied to the rectifying circuit, and pulsed flow having a current cut-off period is supplied from the rectifying circuit to the LED group.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an illumination device using LEDs.

  An illumination device (hereinafter referred to as an LED illumination device) using a light emitting diode (hereinafter referred to as an LED) includes a plurality of LEDs and a drive circuit for supplying a drive current to the LED, and the drive current is supplied to the LED. Supplying the LED causes the LED to emit light. The LED can convert electric power into light more efficiently than other light emitting devices, but the drive circuit generates heat, and this heat generation causes a reduction in the efficiency of the lighting device.

  A driving circuit of a general LED lighting apparatus supplies an LED current for causing a LED group configured by connecting a number of LED elements in series to perform a light emitting action. In a general LED lighting device, the drive circuit of the LED lighting device generates a lot of heat in order to control the LED current 45 flowing in the LED group to an appropriate value, causing a reduction in efficiency. Apart from such a drive circuit with a very large amount of heat generation, an LED lighting device has been developed that suppresses the heat generation amount of the drive circuit of the LED lighting device, and such technology is disclosed in WO2014 / 046254A1 (Patent Document 1).

WO2014 / 046254A1

  The LED illuminating device described in Patent Document 1 does not mention measures for adjusting the amount of light emitted by the LED illuminating device or measures against fluctuations in power supply voltage. It would be very convenient if an LED lighting device that generates a small amount of heat and that can adjust the amount of light emitted by the LED lighting device or that can suppress fluctuations in the amount of emitted light due to fluctuations in power supply voltage can be achieved.

  An object of the present invention is to provide an LED illumination device capable of adjusting the amount of light emitted from the LED illumination device or suppressing the variation in the light emission amount caused by the variation in the power supply voltage.

  The invention that solves the above-described problems includes an LED group configured by connecting a plurality of LEDs that emit light in series based on a supplied light emission current, and a current control circuit that receives an AC voltage from a power supply terminal and supplies an AC current. And a rectifier circuit that rectifies an alternating current from the current control circuit and supplies the rectified current to the LED group, the current control circuit comprising: a first capacitor provided between the power supply terminal and the rectifier circuit; A light emission amount adjusting circuit that is provided in parallel to the first capacitor and changes a current value flowing based on an operation, and a first current flowing through the first capacitor and a second current flowing through the light emission amount adjusting circuit. Is supplied to the rectifier circuit, and a pulsating flow having a current interruption period is supplied from the rectifier circuit to the LED group.

  ADVANTAGE OF THE INVENTION According to this invention, it becomes possible to provide the LED illuminating device which can adjust the light quantity which an LED illuminating device emits, or can suppress the fluctuation | variation of the emitted light amount resulting from the fluctuation | variation of a power supply voltage.

It is a circuit diagram which shows one Embodiment of a LED lighting apparatus. It is explanatory drawing which shows the current waveform of the voltage waveform from an alternating current power supply, a current control circuit, and a light emission amount adjustment circuit. It is a figure which shows the waveform of the LED current which flows through the current by the current control circuit of FIG. 1, and LED group. It is a figure which shows the waveform of the charging / discharging electric current of the capacitor | condenser of the bias circuit described in FIG. FIG. 2 is a current waveform diagram showing a change in LED current flowing through an LED group when the resistance value of the variable resistance value circuit shown in FIG. 1 is changed. It is a circuit diagram which shows other embodiment. It is a figure which shows the change of the LED current which flows through the LED group at the time of changing the resistance value of the resistance value variable circuit of FIG. It is a figure which shows the waveform of the power supply current 15 when the resistance 124 connected in series with the capacitor | condenser 116 described in FIG. It is a figure which shows the waveform of the power supply current 15 at the time of removing the resistance 124 described in FIG. It is a figure which shows other embodiment. It is a figure explaining the change of LED current at the time of changing the capacity | capacitance of the light quantity adjustment circuit of FIG. It is an Example corresponding to the fluctuation | variation of a power supply voltage. It is another Example corresponding to the fluctuation | variation of a power supply voltage.

  The modes for carrying out the invention described below (hereinafter referred to as “examples”) can solve the problems described in the column of problems to be solved by the above-described invention, and are described in the column of effects of the invention. The effects of the invention can be obtained. However, the embodiments described below are not limited to these, and can solve problems other than those described in the column of problems to be solved by the above-described invention, and are also included in the column of effects of the invention. It can also be obtained with effects other than the effects of the described invention. In the drawings used for explaining the various embodiments below, the same reference numerals are assigned to the components having substantially the same functions. Further, the description of the same reference numerals will not be repeated.

[1. Description of Overall Configuration of LED Lighting Device 100 Circuit]
[1.1 Description of circuit configuration]
An example of the overall circuit configuration of the LED lighting device 100 will be described below with reference to FIG. The LED lighting device 100 is connected to an AC power source 102 that is a commercial power source of, for example, 100V through a connection terminal 104 and a power switch 106, and is supplied with power of, for example, 100V from the AC power source 102. The LED lighting device includes a current control circuit 110 having a function as a drive circuit, a full-wave rectifier circuit 200, an LED group 450 that emits light based on a flowing current, and a bias current 24 that is supplied to the LED group 450 to provide LED lighting. A bias circuit 220 is provided to reduce the magnitude of change in the light emission amount of the device 100 over time (hereinafter referred to as flicker).

  A current control circuit 110 shown as an example in FIG. 1 includes a capacitor 114 that supplies a current 12, a light emission amount adjustment circuit 120 that supplies a current 14, and a discharge resistor 112 that functions as a discharge circuit. The full-wave rectifier circuit 200 is supplied with current 12 and current 14 from the AC power supply 102 via the capacitor 114. An alternating current is also supplied to the full-wave rectifier circuit 200 via the discharge resistor 112, but the current value supplied to the full-wave rectifier circuit 200 via the discharge resistor 112 is much higher than the current 12 and the current 14. It is a small value, and the influence on the issuing operation of the LED group 450 is very small. Therefore, in the following description, the current supplied to the full-wave rectifier circuit 200 via the discharge resistor 112 is ignored.

  The resistor 124 and the resistor 126 constitute a resistance value variable circuit 122, and the current 14 flowing through the capacitor 116 can be changed by changing the resistance value of the resistor 126 from a predetermined value, for example, 10 KΩ to zero Ω. Although only the resistor 126 may be provided without providing the resistor 124, when both the resistor 124 and the resistor 126 are provided, the amount of heat generated by the current 14 may be distributed to the resistor 124 and the resistor 126. It is possible to suppress the temperature rise of individual resistors. For example, the LED lighting device 100 can be attached to the ceiling or the like, and only the resistor 126 of the variable resistance circuit 122 can be taken out of the LED lighting device 100 and attached to the user. In such an arrangement, the user can adjust the brightness of the LED lighting device 100 by changing the current value of the LED current 45 flowing through the LED group 450 by setting the resistance value of the resistor 126 by operation. . That is, when the operator changes the resistance value of the resistor 126, the resistance value of the resistance value variable circuit 122 connected in series with the capacitor 116 can be adjusted, and the light emission amount of the LED lighting device 100, that is, dimming can be performed. . By providing the resistor 124, heat generation of the resistor 126 formed of a variable resistor can be suppressed, and the influence of heat of the resistor 126 can be reduced. Reduction in the amount of heat generated by the resistor 126 leads to a longer life of the resistor 126.

  In FIG. 1, the supply power of the AC power supply 102 is 100 V 50 Hz, the capacitor 114 is 2.2 μF, the capacitor 116 is 1.0 μF, the total resistance value of the variable resistance circuit 122 is 400Ω, the resistance value of the discharge resistor 112 is 1 MΩ, the resistance 226 is 1 KΩ, resistor 228 is 500 kΩ, capacitor 224 is 2 μF, LED group 450 is a white LED 35 series circuit, AC voltage supplied from AC power supply 102, current 12, current 14, AC current Sixteen waveforms are shown in FIG. This waveform is a simulation result that is simulated using a Quiet Universal Circuit Simulator (hereinafter referred to as QUICS), which is a simulation program for which usage methods and explanations are provided by Yamanashi University and Tottori University. The waveforms shown in the other figures shown below are also the results of simulation by QUICS.

  The waveform in FIG. 2 shows a state between 0.02 seconds and 0.04 after the power switch 106 is closed. During this period, the operation is in a steady state, and a similar waveform is repeated as time passes. However, the description is omitted, and only a state between 0.02 seconds and 0.04 is described. Current 12, current 14, and AC current 16 are all in advance phase with respect to AC voltage 10 supplied from AC power supply 102. From the viewpoint of the advance phase, current 12, current 14, and AC current 16 are all AC. The current flows prior to the rise of the voltage 10, but the output voltage of the full-wave rectifier circuit 200 is higher than the voltage applied to the LED group 450 from the bias circuit 220 in the period from 0.02 seconds to time t1 in FIG. It is in a low state and the current 20 does not flow. That is, the voltage between the output terminals of the full-wave rectifier circuit 200 is smaller than the voltage between the terminals of the LED group 450, and the current 20, the current 12, and the current 14 do not flow.

  At the time t1 when the voltage output from the full-wave rectifier circuit 200 becomes higher than the voltage between the terminals of the LED group 450, the current 20 starts to flow, and the current 12 and the current 14 start to flow. The alternating current 16 supplied to the full-wave rectifier circuit 200 is a vector sum of the current 12, the current 14, and the current flowing through the discharge resistor 112. As described above, the current flowing through the discharge resistor 112 is much smaller than the current 12 and the current 14, and is ignored here. The output voltage of the full-wave rectifier circuit 200 decreases with an increase in the charge of the capacitors 114 and 116, the current 12 and the current 14 gradually decrease, and the alternating current 16 that is the vector sum thereof gradually decreases. At time t2, the output voltage of the full-wave rectifier circuit 200 becomes lower than the terminal voltage of the LED group 450, and the current values of the current 20, the alternating current 16, the current 12, and the current 14 are cut off. Of course, a discharge current flows through the discharge resistor 112, but since the current value is small as described above, the current value of the discharge resistor 112 is ignored in the above description.

  In the period between the time point t2 and the time point t1 illustrated in FIG. 2, the alternating current 16 does not flow. For this reason, the current 20 does not flow during the period between the time point t2 and the time point t1. FIG. 3 shows the waveforms of current 20 and LED current 45. The current 20 flows as shown in the period diagram from the time point t1 to the time point t2, and does not flow during the period between the time point t2 and the time point t1. The bias current 24 supplied from the bias circuit 220 is supplied to the LED group 450 together with the current 20 as described below. The period between the time point t2 and the time point t1 is a period in which the current 20 is not supplied, but since the bias current 24 is continuously supplied, the LED current 45 has a small current value, but the period between the time point t2 and the time point t1 Continues to flow. As a result, the LED current 45 continues to emit light although the amount of light emission decreases.

  FIG. 4 is a graph showing a waveform of the charging / discharging current 22 of the capacitor 224 included in the bias circuit 220. The graph is shown in a direction in which the discharge current of the current 22 flowing through the capacitor 224 is a positive value and the charging current is a negative value. Therefore, the negative waveform that starts to flow from the time point t1 in FIG. 4 represents the charging current that flows into the capacitor 224 via the diode 222. On the other hand, a waveform showing a positive value in FIG. 4 represents the bias current 24 supplied from the capacitor 224 to the LED group 450 via the resistor 226.

  The diode 222 of the bias circuit 220 serves to increase the charging current of the capacitor 224. When the diode 222 is removed, the charge / discharge current of the capacitor 224 flows through the resistor 226. The charging current of the capacitor 224 decreases, and as a result, the bias current 24 also decreases.

  An LED current 45 shown in FIG. 3 flows through the LED group 450, and the LED group 450 performs a light emitting operation according to the LED current 45. Each 452 constituting the LED group 450 is configured by, for example, a white LED assuming general illumination, but is not limited to a white LED. Colors other than white, for example, red, orange, yellow, green, blue, or a mixture thereof may be used. For example, when used as a lighting device for growing plants, LEDs of a plurality of colors may be periodically arranged so that light having a frequency suitable for plants is emitted. If the light emission color is different, the voltage between the terminals of the LED is different. However, even if the LED group 450 shown in FIG. As will be described below, the LED lighting device 100 generates a very small amount of heat, and is suitable for use in a container lighting device having a refrigeration function, a plant growing lighting device, and the like.

[1.2 Transient response to operation of power switch 106]
In the above description, the operation in the steady state has been described. However, when the power switch 106 is opened, it is desirable to quickly discharge the accumulated charges of the capacitor 114, the capacitor 116, and the capacitor 224 when the power switch 106 is opened. For example, when the operator repeatedly opens and closes the power switch 106 within a short period of time, a new voltage is applied again with the accumulated charges in the capacitor 114, the capacitor 116, and the capacitor 224 accumulated. For example, in the capacitor 114 and the capacitor 116, when the power switch 106 is turned on again, there is a possibility that a voltage having an opposite phase to the accumulated charge is applied. In this case, a large current flows. From this point of view, it is desirable to quickly discharge the accumulated charges of 114, capacitor 116, and capacitor 224. The discharge resistor 112 constitutes a discharge circuit for discharging the charges of the capacitor 114 and the capacitor 116. 228 constitutes a discharge circuit for discharging the charge accumulated in the capacitor 224. Although the discharge resistance 112 is described as 1 MΩ, a resistance value of 100 kΩ or 50 kΩ may be used in order to enhance the discharge effect. When the opposing value of the discharge resistor 112 is 10 kΩ, the current value of the LED current 45 changes due to the current flowing through the discharge resistor 112, and the characteristics of the LED lighting device 100 change. In this case, it is necessary to set the overall characteristics in consideration of the current flowing through the discharge resistor 112. The resistance value of the resistor 226 can be changed from 50 kΩ to 1 MΩ. When the resistance value of the resistor 226 is 50 kΩ or less, the current value of the bias current 24 decreases.

[1.3 Explanation of flicker prevention]
In FIG. 3, the current 20 is interrupted between time t2 and time 1. For this reason, when the LED group 450 is driven only by the current 20, the LED group 450 is turned off and a flicker phenomenon occurs. 3 receives the bias current 24 from the bias circuit 220 during the cutoff period of the current 20, and the LED group 450 continues to emit light even during the cutoff period of the current 20. Thereby, the flicker phenomenon can be suppressed.

[2. (Explanation of light emission switching operation)
[2.1 Explanation of light emission amount setting and dimming operation]
The amount of light emitted from the LED group 450 can be changed by changing the value of the LED current 45 flowing through the LED group 450 shown in FIG. The current 12 flowing through the capacitor 114 is set to be a reference value that determines the minimum brightness of the LED lighting device 100. When the capacitance of the capacitor 114 is increased, the value of the current 12 is increased, and the minimum reference value of brightness is shifted in the direction of increasing brightness. On the other hand, when the capacitance of the capacitor 114 is reduced, the minimum reference value of the brightness of the LED lighting device 100 is shifted in the direction of darkening. Thus, the minimum reference value of brightness can be set by changing the capacitance of the capacitor 114. Moreover, the maximum value of the brightness of the LED lighting device 100 can be set by setting the current 14 that flows through the capacitor 116 when the resistance value of the resistance value variable circuit 122 is set to a minimum value, for example, zero Ω. The maximum current of the current 14 that determines the maximum value of brightness can be determined by setting the capacitance of the capacitor 116. The maximum value of brightness is determined by the current value of the alternating current 16 that is the total value of the current 12 and the current 14 when the resistance value of the resistance value variable circuit 122 is minimized.

  If the circuit constants are determined as described above, the capacitor 114 is set to 2.2 μF, and the capacitor 116 is set to 1.0 μF, the values of the other circuit components are set to the values described above, and the resistance value of the resistance variable circuit 122 is changed. FIG. 5 shows a change in the current of the LED current 45 in the case of being made. A waveform of the LED current 45 flowing through the LED group 450 when the resistance value of the resistance variable circuit 122 is 400Ω is indicated by an LED current 45 (1). The waveform of the LED current 45 (1) is a pulsating current, and the peak value is about 100 mA. A waveform of the LED current 45 when the resistance value of the resistance value variable circuit 122 is increased to 1200Ω is indicated by an LED current 45 (2). The peak value of the waveform of the LED current 45 is about 85 mA, which is lower than that of the waveform of the LED current 45 (1). A waveform of the LED current 45 when the resistance value of the resistance value variable circuit 122 is further increased to 2000Ω is indicated by an LED current 45 (3). The peak value of the waveform of the LED current 45 is about 80 mA, which is further lower than the peak value of the waveform described above. A waveform of the LED current 45 when the resistance value of the resistance value variable circuit 122 is 4000Ω is indicated by an LED current 45 (4). The peak value of the waveform of the LED current 45 is about 70 mA and is further lowered. In this way, by changing the resistance value of the resistance value variable circuit 122, the peak value of the LED current 45 flowing through the LED group 450 can be changed, and the brightness of the LED lighting device 100 can be adjusted. Increasing the resistance value of the variable resistance value circuit 122 decreases the light emission amount of the LED group 450, and decreasing the resistance value of the variable resistance value circuit 122 increases the light emission amount of the LED group 450.

[2.2 Effects of the dimming operation shown in FIG. 1]
The minimum light emission amount of the LED lighting device 100 can be set by the capacitor 114. In the embodiment of FIG. 5, the capacitor 114 can set a current having a peak value of 70 mA with respect to the LED current 45 having a peak value of 100 mA. Capacitors generate less heat than resistors. Since the current corresponding to the lowest brightness among the LED currents 45 can be set by a capacitor with little heat generation, the heat generation amount of the light emission amount adjustment circuit 120 can be extremely reduced. Since the current value corresponding to the change in brightness adjustment, that is, dimming is set by the light emission amount adjustment circuit 120, the current value flowing through the light emission amount adjustment circuit 120 is suppressed to a value much smaller than the LED current 45, so A calorific value of 100 can be suppressed. In the above description, the capacitor 114 is 2.2 μF and the capacitor 116 is 1.0 μF, but the capacitor 114 may be 1 μF and the capacitor 116 may be 2.2 μF in order to further expand the brightness adjustment range. It is desirable that the capacitance of the capacitor 114 that sets the minimum reference value of brightness be in the range of about one third to two thirds of the total capacitance of the current control circuit 110. When the capacitance of the capacitor 114 is about one third of the total capacitance of the current control circuit 110, about one third of the LED current 45 can be set using a capacitor with a small amount of heat generation. it can. When the capacitance of the capacitor 114 is set to two-thirds of the total capacitance of the current control circuit 110, about two-thirds of the LED current 45 can be set using a capacitor with a small amount of heat generation. it can.

  Further, since the light emission amount adjusting circuit 120 is constituted by a series circuit of the capacitor 116 and the variable resistance value circuit 122, the impedance based on the capacitor 116 for suppressing the current 14 for adjusting the brightness and the resistance value of the variable resistance value circuit 122. Can be controlled. When the capacitor 116 is 1 μF, the impedance of the capacitor 116 is about 3.2K. When the capacitor 116 is 2 μF, the impedance of the capacitor 116 is about 1.6K. A portion corresponding to this impedance can be generated by a capacitor with very little heat generation, and as a result, heat generation of the light emission amount adjusting circuit 120 can be reduced. Further, in the brightest state, that is, in the state where the current 14 is the largest, the resistance value of the resistance value variable circuit 122 is a very small value, for example, zero Ω, so heat generation can be greatly suppressed, and the LED lighting device 100 maintains higher efficiency. it can.

  In the example illustrated in FIG. 1, the variable resistance circuit 122 includes a resistor 124 that is a fixed resistor and a resistor 126 that is a variable resistor, and suppresses heat generation of the variable resistor. Thus, the lifetime of the variable resistor 126 can be extended by adopting a configuration that suppresses heat generation of the variable resistor. Compared to a resistor having a fixed resistance value, the variable resistor has a tendency to shorten its life as the temperature rises. By reducing the current value of the resistor 126, which is a variable resistor, as in this embodiment, The reliability of the LED lighting device 100 can be improved.

  Moreover, since the heat generation of the light emission amount adjustment circuit 120 can be suppressed as described above, the LED group 450 and the current control circuit 110 can be arranged on the same resin circuit board. Further, the LED lighting device 100 can be downsized without a high temperature without using special heat radiating metal fins.

[3.1 Description of another embodiment of LED lighting device 100 having a light emission amount control function]
Another embodiment of the LED lighting device 100 having the function of adjusting the light emission amount of the LED group 450 is shown in FIG. Since the configuration of the same reference numerals performs substantially the same operation, detailed description thereof is omitted. When an AC voltage from the AC power supply 102 is applied to the current control circuit 110 via the connection terminal 104 and the power switch 106, a current controlled based on the capacitor 114 is supplied to the full-wave rectification circuit 200. The peak value of the waveform supplied to the full wave rectifier circuit 200 is determined by the capacitance of the capacitor 114. The full-wave rectification circuit 200 performs full-wave rectification on the AC waveform supplied from the current control circuit 110 and replaces it with a pulsating waveform. This pulsating flow waveform has a cut-off period in which no current flows like the current 20 in FIG. This blocking period increases as the number of LED elements in the LED group 450 in series (hereinafter referred to as the number of stages) is increased.

  The AC voltage from the AC power supply 102 is also supplied to the bias circuit 240 via the connection terminal 104 and the power switch 106. The bias circuit 240 operates in the same manner as the bias circuit 220. In the bias circuit 220 described above with reference to FIG. 1, the current 16 controlled by the current control circuit 110 is added to the full-wave rectifier circuit 200, and the pulsating current rectified by the full-wave rectifier circuit 200 is supplied. Therefore, the value of the charging current supplied to the capacitor 224 included in the bias circuit 220 is small, and the charging period during which the charging current is supplied to the capacitor 224 is short. Therefore, the LED current 45 supplied from the bias circuit 220 to the LED group 450 has a small value.

  An AC voltage is directly supplied from the AC power supply 102 to the bias circuit 240 illustrated in FIG. 6 without passing through the current control circuit 110. Therefore, a larger current can be taken in compared with the bias circuit 220 of FIG. The bias circuit 240 includes a full-wave rectifier circuit 242, a capacitor 244, a resistance variable circuit 130, and rectifiers 246 and 248. Capacitor 244 operates corresponding to capacitor 224. The resistance value variable circuit 130 operates corresponding to the resistance value variable circuit 122. When the resistance value of the resistance value variable circuit 130 is increased by a dimming operation, the LED current 45 supplied from the bias circuit 240 to the LED group 450 decreases. The light emission amount of the LED group 450 decreases. Conversely, when the resistance value of the resistance value variable circuit 130 is decreased by the dimming operation, the LED current 45 supplied from the bias circuit 240 to the LED group 450 increases, and the light emission amount of the LED group 450 increases. In this way, the user can adjust the brightness of the LED lighting device 100 by changing the resistance value of the resistance value variable circuit 130. Note that although the rectifier 246 and the rectifier 248 are provided to stabilize the operation, the rectifier 246 and the rectifier 248 operate without the rectifier 246 and the rectifier 248.

FIG. 7 shows a change in the LED current 45 flowing through the LED group 450 when the resistance value of the resistance value variable circuit 130 shown in FIG. 6 is changed. The capacitor 114 is 1 μF, the capacitor 116 is 2 μF, the resistor 124 is 400Ω, the capacitor 244 is 4 μF, the discharge resistor 112 is 1 MΩ, and the resistor 245 provided in parallel with the capacitor 244 is 500 kΩ. The resistor 245 acts to discharge the electric charge stored in the capacitor 244 when the power switch 106 is opened. Regarding the adjustment of the brightness of the LED lighting device 100, the resistor 245 does not act directly. The resistor 245 is provided to maintain safety.
In the waveform of the LED current 45 shown in FIG. 7, the LED current 45 (11) is a waveform when the values of the resistors 132 and 134 are each 100Ω, and the peak value is about 340 mA. The LED current 45 (12) is a waveform when the values of the resistors 132 and 134 are set to 150Ω, and the peak value is about 245 mA. The LED current 45 (13) is a waveform when the values of the resistors 132 and 134 are 200 Ω, respectively, and the peak value is about 200 mA. The LED current 45 (14) is a waveform when the values of the resistors 132 and 134 are 300 Ω, respectively, and the peak value is about 150 mA. The LED current 45 (15) is a waveform when the values of the resistors 132 and 134 are 500 Ω, respectively, and the peak value is about 120 mA. The LED current 45 (16) is a waveform when the values of the resistors 132 and 134 are 700 Ω, respectively, and the peak value is about 100 mA. The LED current 45 (17) is a waveform when the values of the resistors 132 and 134 are 1000 Ω, and the LED current 45 (18) is a waveform when the values of the resistors 132 and 134 are 2000 Ω, respectively. 45 (19) is a waveform when the values of the resistors 132 and 134 are each 10000Ω. When the values of the resistors 132 and 134 are 1000Ω or less, the peak value of the LED current 45 changes greatly according to the change of the resistance value. However, in the state where the values of the resistors 132 and 134 are respectively larger than 1000Ω, the LED The peak value of the current 45 hardly changes. Therefore, for the operation of switching the light emission amount of the LED lighting device 100, that is, the dimming operation, it is preferable to set the values of the resistors 132 and 134 to 1000Ω or less.

  In FIG. 6, when the current value of the LED current 45 during the period in which the alternating current 16 from the current control circuit 110 is cut off, the resistances 132 and 134 of the resistors 132 and 134 are compared with the case where the values of the resistors 132 and 134 are 1000Ω or less. When the value is larger than 1000Ω, the current value of the LED current 45 decreases. For example, looking at the time of 0.03 seconds, when the values of the resistors 132 and 134 are made larger than 1000Ω, the current value of the LED current 45 is lowered. A larger supply current from the bias circuit 240 during the period in which the alternating current 16 from the current control circuit 110 is cut off is effective in preventing flickering of the LED lighting device 100. Also from this point, it is desirable to set the values of the resistors 132 and 134 to 1000Ω or less.

  By inserting a resistor or a coil in series with the capacitor 114 or the capacitor 116 of the current control circuit 110, the power source current 15 supplied to the LED lighting device 100 can be made into a smooth waveform, and the entire LED lighting device 100 can be supplied. Current, that is, harmonics of the power supply current 15 of the LED lighting device 100 can be suppressed. In the circuit of FIG. 6, a resistor 124 is connected in series with a capacitor 116. Further, a resistor connected in series with the capacitor 114 may be provided. Alternatively, a resistor or a coil may be connected between 110 and the full-wave rectifier circuit 200. FIG. 8 shows a waveform of the power supply current 15 when the resistor 124 is connected in series with the capacitor 116 in series as shown in FIG. 6 and the resistance value of the resistor 124 is 400Ω. At the same time, the power supply voltage waveform of the AC power supply 102 is displayed. 9 shows the power supply voltage waveform of the AC power supply 102 and the waveform of the power supply current 15 as in FIG. However, the waveform shown in FIG. 9 is when the value of the resistor 124 is zero, that is, when the resistor 124 is removed.

  The alternating current 16 supplied from the current control circuit 110 to the LED group 450 via the full-wave rectifier circuit 200 is greatly advanced in phase with respect to the power supply voltage. On the other hand, the bias current 24 supplied from the bias circuit 240 to the LED group 450 is substantially in phase with the power supply voltage. For this reason, the waveform of the power supply current 15 shown in FIG. 9 is such that the alternating current 16 of the current control circuit 110 first suddenly rises and the bias current 24 of the bias circuit 240 suddenly rises when the alternating current 16 begins to decrease. For this reason, the change of the power supply current 15 due to the connection between the alternating current 16 and the bias current 24 becomes large. This change increases the generation of harmonics. On the other hand, in the case shown in FIG. 8, the alternating current 16 rises more smoothly than in the state of FIG. 9, so the connection with the rising portion of the bias current 24 becomes smoother, and the generation of higher harmonics than in the state of FIG. Is suppressed.

[3.2 Effects of the embodiment shown in FIG. 6]
In FIG. 6, the bias circuit 240 receives the power supply voltage without passing through the current control circuit 110 and supplies the bias current 24 to the LED group 450. For this reason, the current value of the bias current 24 can be increased. Further, the bias current 24 supplied from the bias circuit 240 is delayed in phase as compared with the AC current 16 supplied from the current control circuit 110, so that it is suitable for supplying the bias current 24 during the interruption period of the AC current 16. . Furthermore, the power factor of the LED lighting device 100 can be improved.

  By increasing the value of the capacitor 244 included in the bias circuit 240, the supply can be increased to the bias current 24 in the period between the time point t2 and the time point t1 illustrated in FIGS. it can. As a result, the current during the period between time t2 and time t1 of the LED current 45 increases, and flickering of the LED lighting device 100 can be reduced.

[4 Dimming of multiple LED groups 450 and LED groups 451]
Two sets of the LED groups 450 described above are provided (hereinafter, one is referred to as an LED group 451), and the current control circuit 110 (hereinafter, one is referred to as the current control circuit 111) and the bias circuit 220 (hereinafter, one is biased). In the case of operating with the current from the circuit 221), if a dimmer is provided for each of the LED group 450 and the LED group 451, the operation may become troublesome. In the circuit of FIG. 10, the light emission amount of the plurality of LED groups 450 and 451 can be adjusted by one light emission amount adjustment circuit 250. The basic operations of the current control circuit 110, the current control circuit 111, the bias circuit 220, the bias circuit 221, the LED group 450, and the LED group 451 are as described above, and a description thereof will be omitted. Instead of the bias circuit 220, a light amount adjustment circuit 250 that receives an AC voltage from the power supply without using the current control circuit 110, such as the bias circuit 240, may be used.

  A light amount adjustment circuit 250 that supplies current 32 and current 34 to the plurality of LED groups 450 and 451 is provided. The value of the AC current 17 supplied from the AC power supply 102 to the full-wave rectifier circuit 150 of the light amount adjustment circuit 250 via the connection terminal 104 or the power switch 106 can be changed by switching the capacitance of the capacitor 142. The alternating current 17 is rectified by the full-wave rectifier circuit 150 and supplied as the current 32 and the current 34 to the LED group 450 and the LED group 451 through the rectifier 152 and the rectifier 154, respectively, and the light emission amount of the LED group 450 and the LED group 451 is increased. Can be changed. Current 32 and current 34 return to full-wave rectifier circuit 150 via rectifier 156 and rectifier 158, respectively.

  For example, the capacitor 142 includes a plurality of capacitors, and has a structure in which the capacitance of the capacitor 142 is changed by selecting with a changeover switch. Thus, when the user operates the changeover switch, the light emission amounts of the LED group 450 and the LED group 451 which are a plurality of light emitting means can be changed. Since the capacitance of the capacitor 142 is switched, the amount of heat generation is small and high efficiency can be maintained. The resistor 144 is used for adjusting the set value. It works even if it is not provided.

  In the circuit of FIG. 10, when the capacitor 114 of the current control circuit 110 and the current control circuit 111 is 1.5 μF, the LED group 450 and the LED group 451 are in a series structure of 35 white LED elements, and the capacitance of the capacitor 142 is changed. A waveform of the LED current 45 of the LED group 450 or the LED group 451 is shown in FIG. However, in order to make the relationship between the capacitance of the capacitor 142 and the change in the LED current 45 easier to understand, the bias circuit 220 and the bias circuit 221 are separated, and the bias current supplied from the bias circuit 220 and the bias circuit 221 is shown in FIG. It is not supplied in 11 waveforms. The resistor 144 is 50Ω.

  The LED current 45 when the capacitor 142 is 4 μF is the waveform of the LED current 45 (22). The LED current 45 when the capacitor 142 is 3 μF is the waveform of the LED current 45 (24). The LED current 45 when the capacitor 142 is 0.5 μF is the waveform of the LED current 45 (26). The LED current 45 flowing through the LED group 450 and the LED current 45 flowing through the LED group 451 are exactly the same, and FIG. 11 shows the waveform. Thus, when the capacity of the capacitor 142 is increased, the peak value of the LED current 45 flowing through the LED group 450 or the LED group 451 can be changed, and the light emission amount of the LED group 450 or the LED group 451 can be adjusted. When the resistance value of the resistor 144 is increased, the peak value of the LED current 45 shown in FIG. 11 is decreased, and the light emission amount is decreased. On the other hand, when the resistance value of the resistor 144 is decreased, the peak value of the LED current 45 shown in FIG. 11 is increased, and the light emission amount is increased.

  In this way, the amount of light emitted from a plurality of LED groups can be adjusted simultaneously with a simple circuit, and not only the circuit is simple but also the operability is improved. In addition, since it generates very little heat, it can be installed on the wall of a building, etc., and since it does not become high temperature, high safety can be maintained.

[5 Response to voltage drop]
In the lighting of a manufacturing plant, there is a possibility that the power supply voltage for lighting temporarily decreases as the load current of the motor or the like increases. The circuit described in FIG. 12 is a circuit diagram of the LED lighting device 100 including a circuit corresponding to a decrease in power supply voltage. The configuration with the same reference numerals as the configuration described above performs the same operation and has the same effect, so the repeated description is omitted here. Further, the bias circuit 240 may be used instead of the bias circuit 220.

  When the voltage of the power supplied from the AC power supply 102 decreases, the value of the AC current 16 supplied from the current control circuit 110 to the full-wave rectifier circuit 200 decreases, the LED current 45 flowing through the LED group 450 decreases, and the LED group The light emission amount of 450 decreases. The current 12 flowing through the capacitor 114 can be detected by the resistor 516 and the current detection circuit 514, and a decrease in the power supply voltage can be detected. When the current detection circuit 514 detects a drop in the power supply voltage, the current control circuit 512 is operated to increase the current 12. For example, a capacitor may be connected in parallel with the capacitor 114. Even if it is not possible to completely prevent a decrease in the light emission amount of the LED group 450 due to a temporary voltage drop, discomfort can be reduced if the decrease in the light emission amount can be suppressed to some extent. Further, in this circuit, it is possible to adjust the change in brightness with a power source of 50 Hz and 60 Hz. When power is supplied from a commercial power supply of 60 Hz rather than a commercial power supply of 50 Hz, the value of the current 12 of the capacitor 114 increases, and the amount of light emitted from the LED group 450 increases. By detecting the value of the current 12 with the current detection circuit 514 and the resistor 516 and controlling the current with the current control circuit 512, a change in brightness due to the difference between 50 Hz and 60 Hz can be corrected.

  By connecting a capacitor in parallel with the capacitor 114 by the current control circuit 512, a considerable failure can be suppressed without high control accuracy. In this case, the amount of heat generation can be greatly reduced as compared with a method in which the LED current 45 flowing through the LED group 450 is feedback-controlled to a constant value. In order to control with higher accuracy, a current control circuit 513 for controlling the current value of the capacitor 116 may be further provided. However, in the circuit that adjusts the light emission amount of the LED group 450 by controlling the current of the capacitor 116 by the resistor 126, it may be temporarily difficult to adjust the light emission amount when the power supply voltage decreases.

  When the supply voltage from the AC power supply 102 is constant, the current 12 detected by the resistor 516 is determined by the capacitor 114. The current 12 is an alternating current, and the current detection circuit 514 may accumulate a half cycle or one cycle of current in a capacitor or the like, take out the accumulated charge as a voltage, and compare it with a reference value. Note that if the current for one cycle is simply averaged, the average value becomes zero, so it is desirable to rectify and average.

[6 Other examples of voltage drop response]
FIG. 13 shows another embodiment for dealing with a voltage drop. The same reference numerals as those in the above-described configuration perform the same operation and produce the same effect. AC power from the AC power supply 102 is stored in a capacitor 540 included in the DC power supply 526 via the current control circuit 522 and the full-wave rectification circuit 524. The terminal voltage of the capacitor 540 is detected by the voltage detection circuit 528, and the current control circuit 522 controls the current so that the DC voltage stored in the DC power supply 526 is always a constant voltage. For example, the current conduction angle for each half cycle of AC is controlled. In this way, a constant voltage is supplied from the DC power source 526 to the DC / AC converter 530 that converts DC to AC. The DC / AC converter 530 converts direct current power into alternating current power having a constant peak value.

  Even if the voltage of the AC power supply 102 temporarily decreases, the feedback function configured by the DC power supply 526, the voltage detection circuit 528, and the current control circuit 522 can suppress the influence due to the voltage decrease.

  In addition, the DC / AC converter 530 generates alternating current with a full-wave rectifier circuit of 200 Hz and a high frequency of 300 Hz, and supplies it to the current control circuit 110, so that the capacitors 114 and 116 are compared with the power supply voltage of 50 Hz and 60 Hz. The same brightness can be achieved by reducing the capacity. Since an electrolytic capacitor cannot be used for the capacitor 114 or the capacitor 116, a multilayer ceramic capacitor is used. It is very difficult to make more than 2μF with multilayer ceramic capacitors. For this reason, a plurality of capacitors are connected in parallel. Individual capacitors are also very expensive. Capacitance of the capacitor 114 and the capacitor 116 can be reduced. Not only in terms of price, but also in terms of reliability and ease of manufacturing in the manufacturing process, there are significant effects.

  DESCRIPTION OF SYMBOLS 12 ... Current, 14 ... Current, 16 ... AC current, 20 ... Current, 45 ... LED current, 100 ... LED lighting device, 102 ... AC power supply, 104 ... Connection terminal 106: Power switch 110 ... Current control circuit 114 ... Capacitor 116 ... Capacitor 120 ... Light emission amount adjustment circuit 122 ... Resistance value variable circuit 124・ ・ ・ Resistance, 126 ... Resistance, 130 ... Resistance variable circuit, 200 ... Full wave rectification circuit, 220 ... Bias circuit, 224 ... Capacitor, 226 ... Resistance, 228 ..Resistance and bias circuit 240 ... Bias, 450 ... LED group, 514 ... Current detection circuit, 512 ... Current control circuit, 513 ... Current control circuit, 522 ... Current control circuit 524 ... Wave rectifier circuit, 526 ... DC power source, 530 ... DC / AC conversion circuit.

Claims (6)

A group of LEDs configured by connecting a plurality of LEDs that emit light based on the supplied light emission current in series;
A current control circuit for receiving an alternating voltage from a power supply terminal and supplying an alternating current;
A rectifier circuit that rectifies an alternating current from the current control circuit and supplies the rectified current to the LED group,
The current control circuit includes: a first capacitor provided between the power supply terminal and the rectifier circuit; and a light emission amount adjustment circuit that is provided in parallel with the first capacitor and changes a current value flowing based on an operation. A first current flowing through the first capacitor and a second current flowing through the light emission amount adjusting circuit are supplied to the rectifier circuit, and a pulsating current having a current cutoff period is supplied from the rectifier circuit to the LED group. An illumination device using an LED characterized by that. In the illuminating device using LED of Claim 1,
The illumination device using an LED, wherein the light emission amount adjusting circuit includes a series circuit of a second capacitor and a variable resistance value circuit. In the illuminating device using LED of Claim 2,
A lighting device using an LED, further comprising a bias circuit, wherein a bias current is supplied from the bias circuit to the LED group at least during the current interruption period of the pulsating current. A group of LEDs configured by connecting a plurality of LEDs that emit light based on the supplied light emission current in series;
A current control circuit for receiving an alternating voltage from a power supply terminal and supplying an alternating current;
A rectifier circuit that rectifies an alternating current from the current control circuit and supplies a pulsating current having a cutoff period to the LED group;
A bias circuit that receives an AC voltage from a power supply terminal and supplies a bias current to the LED group at least during the interruption period of the pulsating current; and
The bias device has a resistance value variable circuit that changes the bias current value based on an operation, and the illumination device using the LED. A first LED group and a second LED group configured by connecting a plurality of LEDs that emit light in series based on a supplied light emission current;
First and second current control circuits for receiving an alternating voltage from a power supply terminal and supplying an alternating current;
First and second rectifier circuits for generating a pulsating current having a cutoff period for rectifying an alternating current from the current control circuit and supplying the rectified current to the first or second LED group; ,
AC current supplied by the first current control circuit is rectified by the first rectifier circuit to supply a pulsating current to the first LED group,
AC current supplied by the first current control circuit is rectified by the second rectifier circuit to supply a pulsating current to the second LED group,
A third current control circuit that receives an alternating voltage supplied from the power supply terminal and generates an alternating current for dimming based on an operation;
A third rectifying circuit for rectifying the dimming alternating current, and supplying a third pulsating current from the third rectifying circuit to the first LED group and the second LED group. A lighting device using the featured LED. A group of LEDs configured by connecting a plurality of LEDs that emit light based on the supplied light emission current in series;
A current control circuit for receiving an alternating voltage from a power supply terminal and supplying an alternating current;
A rectifier circuit that rectifies an alternating current from the current control circuit and supplies the rectified current to the LED group,
The current control circuit includes: a first capacitor provided between the power supply terminal and the rectifier circuit; and a light emission amount adjustment circuit that is provided in parallel with the first capacitor and changes a current value flowing based on an operation. And detecting a current flowing through the first capacitor to control the first current flowing through the first capacitor to a predetermined value, and the second current flowing through the first current and the light emission amount adjusting circuit is supplied to the rectifier circuit. An illuminating device using an LED, wherein a pulsating flow having a current interruption period is supplied from the rectifier circuit to the LED group.

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