JP7092323B2 - LED drive method and lighting equipment using the LED drive method - Google Patents

Description

The present invention relates to an LED driving technique for driving an LED row using an AC input, and more particularly, an LED driving method for driving an LED row using an AC input and a lighting device provided with the driving method. Or about lighting equipment.

LED lighting fixtures that use light emitting diodes (LEDs) have the characteristics of longer life and lower power consumption than conventional lighting fixtures such as fluorescent lamps and incandescent lamps. It is expected as a generation of lighting equipment. On the other hand, as short-term issues, problems related to reduction of noise radiated as radio waves (hereinafter referred to as "noise") and harmonics flowing through AC input (hereinafter referred to as "harmonics"), power supply life, cost, etc. Problems have been pointed out. One of the reasons for these problems is that many LED lighting devices currently convert alternating current to direct current and internally drive it with direct current, which requires a complicated LED peripheral circuit including a power supply circuit. It is considered.

As an LED driving method for driving an LED train using an AC input, an LED driving circuit for driving an LED train having a plurality of LEDs connected in series is disclosed (Patent Document 1). More specifically, the LED drive circuit disclosed in Patent Document 1 includes a rectifier that rectifies an AC input, and a plurality of drive transistors connected to the operational capacitor and the output stage of the operational capacitor via a voltage dividing resistor. It has a constant current drive circuit and a resistor as a current detector inserted between the emitters of the plurality of drive transistors, and one end of the output side of the rectifier is connected to the input side of the LED row. By connecting one end on the output side of the plurality of transistors to connection points having different numbers of LED stages in the LED row, the plurality of transistors are selectively driven in the LED row according to the voltage of the AC input. At the same time, the current flowing through the selectively driven LED row also operates so as to fluctuate according to the voltage of the AC input, and when the AC input voltage is low, the LEDs of the LED row are turned on with a small number of stages. The LED train can be kept lit from low to high AC input voltage.

The conventional LED driving method 1 will be further described with reference to FIG. As shown in FIG. 6, in the LED drive circuit 1, the pulsating current Vo rectified by the full-wave rectifier FR1 such as a bridge diode is input to the LED rows D1 to D9 from the AC input (AC power supply). As shown in FIG. 6, the LED row is exemplifiedly composed of nine LEDs (D1 to D9). The MOSFETs Q1 to Q3 of the LED drive circuit 1 operate as a constant current source that also serves as a switch, and by approximating the current waveform flowing in the LED train to a sine wave, the action of suppressing harmonics flowing in the AC input is suppressed. It also has an effect.

First, at the gate of Q1, the voltage obtained by adding the source voltage (Rs1 + Rs2 + Rs3) × I1 of Q1 at that time to the gate-source voltage VGS value of Q1 when the current I1 flows, that is, the voltage of VGS1 + (Rs1 + Rs2 + Rs3) × I1 or more. To make Q1 conductive, and apply a value larger than the voltage value obtained by adding the source voltages of Q2 and Q3 at that time to the VGS values of Q2 and Q3 through which the currents I2 and I3 flow. Keep Q2 in a state where it can conduct electricity. After the voltage at which the pulsating current Vo gradually rises from 0V and the current I1 can flow to Q1 via the first to fourth stage LEDs (D1 to D4), the first to fourth stages The LEDs (D1 to D4) of the eyes light up, but no current flows through the LEDs (D5 to D9) and Q2 and Q3 of the fifth and subsequent stages, and no current continues to flow through Q2 and Q3. Become. At this time, the output voltage Vop of the operational amplifier OP1 is Vop = {VGS1 + I1 × (Rs1 + Rs2 + Rs3)} × (R1 + R2 + R3) / R3, and the relational expression with the reference voltage Vref that determines the current value is Vref × (Rf1 + Rf2) / Rf1 = I1. × (Rs1 + Rs2 + Rs3) = constant.

After the voltage at which the pulsating current Vo rises and the current I2 can flow to Q2 via the LEDs (D1 to D7) in the first to seventh stages, the LEDs D1 to D7 light up. However, no current continues to flow through the 8th and 9th stage LEDs (D8, D9) and Q3. At this time, the output voltage Vop of the operational amplifier OP1 becomes Vop = {VGS2 + I2 × (Rs2 + Rs3)} × (R1 + R2 + R3) / (R2 + R3). The relational expression with the reference voltage Vref is Vref × (Rf1 + Rf2) / Rf1 = I2 × (Rs2 + Rs3). At this time, the values of the resistors R2 and R3 are set so that I1 × Rs1 + (voltage drop of R2) is larger than the difference δVGS of VGS when the current I1 is passed and when the MOSFTE (Q1) is not passed, and Q1 is set during Q2 operation. Make sure that no current flows through.

Further, the voltage Vo rises, and all the LEDs are lit after the voltage at which the current I3 can flow to Q3 via the first-stage to ninth-stage LEDs (D1 to D9). At this time, the output voltage Vop of the operational amplifier OP1 becomes Vop = (VGS3 + I3 × Rs3). The relational expression with the reference voltage Vref is Vref × (Rf1 + Rf2) / Rf1 = I3 × Rs3. Here, the value of the resistance R1 is set so that I2 × Rs2 + (voltage drop of R1) is larger than the difference δVGS of VGS when the current I2 is passed and when the MOSFTE (Q2) is not passed, and Q2 is set during Q3 operation. Make sure that no current flows through. When Q2 is in an inoperable state, the voltage drop of R2 is also added, so that Q1 is also inoperable. From the above description, it can be understood that it is possible to control the current value flowing through the LED by controlling the reference voltage Vref, and thus control the brightness of the LED.
When the voltage decreases, the operation is the reverse of the above.

Japanese Patent No. 5486698

However, the LED drive method described in Patent Document 1 has such a voltage even when the AC input fluctuates and the voltage applied to the LED train drops from the standard voltage value (for example, -10%). The number of LEDs in the LED row is set so that all the LEDs can be turned on in anticipation of a decrease. In this configuration, the number of LEDs mounted is less than the number that can be turned on without problems if the AC input does not fluctuate and is in the standard voltage state, and in the standard voltage state, the voltage range for the reduced number of LEDs is always used. However, it is the main cause of energy loss in this drive method.

More specifically, in the conventional AC drive method, it is designed with the idea of changing the length of the LED row (the number of LEDs) to be lit according to the voltage level, and the biggest problem of this design is. Is controlled so that the LED row to be lit when the voltage is the highest is the longest. In this case, when the voltage drops to a value at which the longest LED row cannot be turned on, an LED that remains completely off appears in one waveform section (within each pulsating current cycle) of the AC voltage among the LED rows arranged in one row. (That is, such a phenomenon may be perceived by consumers as a defective LED). On the other hand, if the voltage fluctuation is monitored and controlled so that all the LEDs are turned on even when the voltage drops in order to prevent such a phenomenon, a loss due to the power supply fluctuation will always occur.

From another point of view, it can be said that the conventional AC drive method has a big problem that the allowable fluctuation range of the input voltage is narrow. On the other hand, looking at the world, even with the so-called AC100V voltage in Japan, there are various values such as 110V, 115V, 120V as well as 100V in the world, and the situation is the same even with AC200V. When trying to deal with these by the conventional AC drive method, it is necessary to develop a product each time according to each voltage, which has become a big problem in terms of development cost and product inventory management.

In view of the above problems, the present invention controls the timing and position of blinking the LED row according to the voltage value so as to efficiently (effectively) utilize the voltage range of the AC input applied to the LED row, and changes the power supply. It is an object of the present invention to provide an LED driving method that realizes reduction of loss (or improvement of power supply usage rate) due to the above, and a lighting device provided with the LED driving method.

Further, the present invention provides an LED driving method capable of operating from a low voltage to a high voltage by widening the AC input voltage range as well as when the voltage applied to the LED train drops by a constant value from the standard voltage value. It is an object of the present invention to provide a lighting device provided with the LED driving method.

In one embodiment of the present invention, in a series-connected LED train having a feeding end as one end, which is driven by a full-wave rectified pulse flow, a plurality of different LED rows starting from the feeding end are set at different locations. It is connected to a different LED drive unit, and the required LED drive unit is operated according to the instantaneous value of the pulsation to control the lighting of the LED from the power supply end to the LED drive unit connection point, and from the power supply end of the LED row. The farthest LED terminal is connected to the drive unit, and the number of lit LEDs is controlled according to the instantaneous value of the pulsation by conducting or short-circuiting between the LED terminals at a preset single or multiple locations in the LED row. It is an LED driving method characterized by doing.

According to the LED driving method according to the embodiment of the present invention and the lighting device provided with the LED driving method, the voltage range of the AC input applied to the LED row is efficiently controlled in the lighting control of the LED row by the AC drive. By controlling the timing and position of blinking the LED row according to the voltage value so that it can be used effectively), it is possible to prevent the generation of LEDs that are completely turned off in one waveform section of AC voltage (within each pulse flow cycle). , It has the effect of reducing the loss caused by the fluctuation of the power supply or improving the power supply usage rate.
Further, according to the LED driving method according to the embodiment of the present invention and the lighting device provided with the LED driving method, not only when the voltage applied to the LED train drops by a constant value from the standard voltage value, but also when the voltage is AC. We can provide LED drive methods that expand the input voltage range to operate from low voltage to high voltage and lighting equipment equipped with the LED drive method, thereby supporting a wide variety of voltages with a small product group. It becomes possible to do.

It is explanatory drawing explaining the LED driving method and the structural example thereof which concerns on one Embodiment of this invention. It is explanatory drawing explaining the LED driving method and the structural example thereof which concerns on other Embodiment of this invention. It is explanatory drawing explaining the LED driving method and the structural example thereof which concerns on other Embodiment of this invention. It is explanatory drawing explaining the LED driving method and the structural example thereof which concerns on still another Embodiment of this invention. It is explanatory drawing for exemplifying the operation principle of this invention. It is explanatory drawing explaining the variation of the full-wave rectifier in the LED driving method which concerns on one Embodiment of this invention. It is explanatory drawing explaining the conventional LED driving method and the configuration example.

In the embodiment of the present invention, in a series of LED trains having a feeding end driven by a full-wave rectified pulse flow as one end, different LEDs in a plurality of different LED rows starting from the feeding end are used. The LED from the power supply end to the LED drive unit connection point is controlled to light up according to the instantaneous value of the connection with the drive unit and the pulse flow, and the LED terminal at the farthest end when viewed from the power supply end of the LED row is the LED drive unit. It is an LED drive method that controls the number of lit LEDs according to the instantaneous value of the pulsation by conducting between the LED terminals of the LED row at one or more locations while connecting to the LED drive method. It is possible to turn on all the LEs during the pulsation cycle, but here, in order to reduce the connection with the drive unit and LED row and make the explanation of control easy to understand, the instantaneous value of the pulsation is VL. The number of LEDs that light up from the feeding end is gradually increased until the value reaches As an example, an operation model in which all LEDs are turned on when the terminals are connected to each other and VH or higher is used as an example. Is in a row, and the number of LEDs is described as 10 when lit at the standard pulsation peak value.

Next, each embodiment for carrying out the LED driving method and the like according to the present invention will be described in detail with reference to the drawings.

The first embodiment of the present invention will be described as relating to the digital control method of the LED drive method, the second embodiment as relating to the analog control method of the LED drive current, and the third embodiment as relating to the digital / analog mixed control method of the LED drive current. do. In order to improve the stability of the circuit system, for example, additional means for ensuring the stability of the system for a series of negative feedback control operations such as DA converter → constant current drive circuit → AD converter → error calculation are appropriately provided. Although sometimes required, these are not essential parts of the invention and are omitted herein to facilitate understanding of the invention.

Alternatively, for the stability of the analog circuit system, response adjustment may be performed by inserting a capacitor (C) or a resistor (R) as appropriate, but these are also not essential parts of the present invention, and are also In order to facilitate the understanding of the present invention, the description thereof will be omitted.

(Basic Concept of the Present Invention)
As described above, the embodiment of the present invention is based on the digital control method (first embodiment), the analog control method (second embodiment), and the digital / analog mixed control method (third embodiment). ), But the basic concept of the present invention is a voltage value in order to prevent "generation of an LED that remains completely extinguished within each pulsation cycle" mentioned as the above-mentioned problem. The point is that the number of lights in the LED row is flexibly changed and controlled, and the position (LED) to be turned on is flexibly controlled. Therefore, it may be an important process to appropriately predict the peak value (hereinafter referred to as the peak value or the like) after a predetermined elapsed time from the reference point including the peak value of the voltage.

Further, in the second embodiment, instead of predicting the peak value of the voltage waveform, the on / off of each switch in the circuit is controlled depending on the voltage level. Therefore, the same LED lighting control as in the first embodiment and the third embodiment is performed. In any case, there is no change in that the number of lights and the lighting position (that is, the LED to be turned on) in the LED row are flexibly controlled according to the voltage level.

When such LED drive control is performed, it is possible to prevent the occurrence of a place (LED position) where the LED lighting stage continues even if the number of lighting stages of the LED is reduced, and the LED is partially turned off instantaneously. It has the effect that people cannot perceive it.

The operating principle of the present invention will be exemplified by reference with reference to FIG.
FIG. 4 shows the high and low of the pulsating current Vo in the LED driving method (specifically, the driving method shown in FIGS. 1A to 3), and the LED controlled to be turned on / off according to the case of each pulsating current Vo. The relationship with the LEDs in the row is explained. The waveform shown in FIG. 4 (A1) is a full-wave rectified waveform (pulsating flow 1 cycle) in the case of AC110V in which the peak value of the pulsating current Vo is 10% higher than the standard value, and (A2) shows (A2). How the LEDs in the LED row are controlled to be turned on / off according to each voltage step of the waveform shown in A1) is illustrated in chronological order. Further, the waveform shown in FIG. 4 (B1) is a full-wave rectified waveform (pulsating flow 1 cycle) when the peak value of the pulsating current Vo is AC100V, which is a standard value, and (B2) shows (B1). ) Is exemplified in chronological order how the LEDs in the LED row are controlled to be turned on / off according to each voltage step of the waveform shown in). Further, the waveform shown in FIG. 4 (C1) is a full-wave rectified waveform (pulsating flow 1 cycle) in the case of AC90V in which the peak value of the pulsating current Vo is 10% lower than the standard value, and is shown in (C2). Illustrates in chronological order how the LEDs in the LED row are controlled to be turned on / off according to each voltage step of the waveform shown in (C1).

FIG. 4 (A1) shows lighting / extinguishing control of the LED of the LED driving method in the full-wave rectified waveform when the voltage value is high. In (A2), the pulse flow Vo rises from the time t10 from the control reference point (the point where the voltage value of the pulse flow Vo becomes the minimum), and the drive control unit by the LED drive method is at times t11 to t12. In the section, the LEDs (D1 to D4) in the first to fourth stages are turned on, and in the section from time t12 to t13, the LEDs (D1 to D7) in the first to seventh stages are turned on, and the time is set. In the section from t13 to t14, the LEDs (D1 to D2) of the first stage to the second stage are turned off, and the LEDs (D8 to D11) of the eighth stage to the eleventh stage are further turned on (that is,). In the same section, D3 to D11 are lit). Next, in the section from time t14 to t15, the second-stage LED (D2) is further lit (that is, in the same section, D2 to D11 are lit), and the section from time t15 to t16 (that is, in the same section). In the section including the peak value of the pulse flow Vo), the LEDs (D1) of the first stage are turned on again to light all the LEDs (D1 to D11) of the first stage to the eleventh stage. .. After that, as the voltage of the pulsating current Vo drops, as for the LED to be turned on, D2 to D11 are turned on in the section from time t16 to t17, D3 to D11 are turned on in the section from time t17 to t18, and time t18. It is sequentially controlled so that D1 to D7 are turned on in the section from t19 and D1 to D4 are turned on in the section from time t19 to t1a.

Further, in (B2) showing the LED lighting / extinguishing control of the LED driving method in the full-wave rectified waveform when the voltage value shown in FIG. 4 (B1) is average, the control reference point (pulse flow Vo) is shown. The pulsating flow Vo rises from time t20 from the point where the voltage value becomes the minimum), and the drive control unit by the LED drive method is the first to fourth stage LEDs (D1) in the section from time t21 to t22. ~ D4) is turned on, the first to seventh stage LEDs (D1 to D7) are turned on in the section from time t22 to t23, and the first to second stages are turned on in the section from time t23 to t24. The LEDs (D1 to D2) of the above are turned off, and the LEDs (D8 to D11) of the eighth to eleventh stages are further turned on (that is, D3 to D11 are lit in the same section. ). Next, in the section from time t24 to t25 (the section including the peak value of the pulsating current Vo), the LED (D2) in the second stage is further turned on (that is, in the same section, D2 to D11 are turned on. Is in a state of being). After that, as the voltage of the pulsating current Vo drops, D3 to D11 are turned on in the section of time t25 to t26, D1 to D7 are turned on in the section of time t26 to t27, and the time t27 is turned on. It is sequentially controlled so that D1 to D4 are turned on in the section from to t28.

Further, in (C2) showing the LED lighting / extinguishing control of the LED driving method in the full-wave rectified waveform when the voltage value shown in FIG. 4 (C1) is low, the control reference point (pulsating current Vo) is shown. The pulsating current Vo rises from time t50 from the point where the voltage value of D1 to D4) are turned on, and the first to seventh stage LEDs (D1 to D7) are turned on in the section from time t52 to t53. Next, in the section from time t53 to t54 (the section including the peak value of the pulsating current Vo), the LEDs (D1 to D2) in the first to second stages are turned off, and the LEDs (D1 to D2) in the eighth stage to the eighth stage are turned off. The 11th stage LEDs (D8 to D11) are further lit (that is, D3 to D11 are lit in the same section). After that, as the voltage of the pulsating current Vo drops, as for the LED to be turned on, D1 to D7 are turned on in the section of time t54 to t55, and D1 to D4 are turned on in the section of time t55 to t56. It is controlled sequentially.

The drive control unit is based on the current pulsating current Vo value (instantaneous voltage value) and the accumulated waveform information (for example, the average value of the latest 4 to 8 waveform information), and the pulsating current Vo peak immediately after that. The value etc. can be predicted. At this time, the peak value and the like can be predicted at any timing, but for more accurate prediction, the prediction is made at the timing immediately before turning on all the LEDs near the peak value of the pulsating current Vo. It is preferable to let it.

Further, in FIG. 4, the number of LEDs in the LED row is set to 11, and the LEDs at the end of the LED row to be switched on / off in order to avoid the generation of LEDs that are completely turned off during the pulsating current cycle. 1 to D2 (the other end is D5 to D11), and the number of drawer ends is three, but the present invention is not limited thereto (see FIGS. 1A to 3 later). The same applies to the embodiment).

Next, the first embodiment to the third embodiment will be described in detail with reference to FIGS. 1A to 3.

[ First Embodiment ] <Digital control method of LED drive current>
FIG. 1A is a configuration example of the LED driving method 110 according to the first embodiment of the present invention. It is a so-called full digital configuration. In such digital control, the circuit output is usually sufficiently slower than the microprocessor response (reverse) as a system stability issue (from the perspective of preventing system instability and oscillation). In many cases, the response of the processor is sufficiently fast. However, there is also a cost request), but the specific specifications are not the essence of the present invention, so detailed explanations are omitted. Hereinafter, it is assumed that the LED driving method 110 clears this problem.

Further, in FIG. 1A, a resistance having a large value (indicated by a broken line in the figure) that does not affect the operation of each MOSFET is mounted between the gate and the source of Q11 to Q15, and when SW101 to SW106 are opened. Was configured so that no current would flow through the MOSFET. Further, the values of I11 to I15 and Rs11 to Rs15 are set in advance, and the characteristics of Q11 to Q15, Q132, and Q142 are known.
That is, the values of the currents I11 to I15 and the values of the resistors Rs11 to Rs15 are values determined by the driver design procedure (that is, if the current to be passed and the reference voltage / reference current for the driver are determined, they are used for the source. The resistance value is determined as a design value).
Similarly, the characteristics required for the transistors Q11 to Q15, and the characteristics required by the transistors Q11 to Q15, depending on the already determined standard input AC voltage, fluctuation rate, number of LED stages, number of switching taps, current value and switching voltage flowing through each tap, and reference voltage, and The value of each resistance of the conduction switching unit 140 and the characteristics of the transistors Q261 and Q262 are also determined naturally.
Hereinafter, the meanings of "values are preset" and "characteristics are known" have the same meaning.

As shown in FIG. 1A, the LED drive method 110 includes a full-wave rectifier FR1, a drive control unit 120, a constant current drive circuit 130 having a plurality of transistors, a conduction switching unit 140, and an LED train (exemplarily, D11 to D11 to). It consists of 11 LED rows up to D1b).

The LED train has N LEDs (N is an integer of 3 or more; 11 in FIG. 1A as an example) connected in series with each other, and has an AC input (AC power supply) to a full-wave rectifier FR1 such as a bridge diode. The full-wave rectified pulsating current Vo is input to the feeding end 150A and the drive control unit 120 of the LED row.

In the embodiment shown in FIG. 1A, the number N of the LEDs (D11 to D1b) is set to 11 in order to facilitate the understanding of the invention, but the present invention is not limited thereto. Further, lead-out ends 151 to 153 are provided for each of different numbers (may be the same number) of LEDs from the feeding end 150A of the LED row, and each is connected to the driving transistors Q11, Q12, and Q13-1. There is. The terminal 150B of the LED row is connected to the driving transistors Q13-2, Q14, and Q15. The number of drawer ends 151 to 153 is not limited to this.

The constant current drive circuit 130 is a circuit including a plurality of driving transistors Q11, Q12, Q13-1, Q13-2, Q14, Q15, a plurality of switches Sw101 to Sw106, and a plurality of resistors Rs11 to Rs14, respectively. Elements are connected as shown in FIG. 1A. The currents I11, I12, I13-1, I13-2, I14, and I15 flowing through the transistors Q11, Q12, Q13-1, Q13-2, Q14, and Q15 are controlled by the control of the switches Sw101 to Sw106 by the drive control unit 120, respectively. Will be done. The number of driving transistors, switches, and resistors included in the constant current drive circuit 130 is not limited to the example shown in FIG. 1A, and the number of LEDs included in the LED row and the LED row through which the currents I11 to I15 flow. It is changed according to the number of lead wires from and the input AC voltage. Further, in this description, the LEDs are described as one row, but various connection forms such as parallel, series-parallel, and changing the number of parallels are possible, and these are described as one row as a representative.

Here, in the present embodiment, MOSFETs are used as transistors Q11, Q12, Q13-1, Q13-2, Q14, and Q15, and semiconductor switches (CMOS, MOSFETs, bipolar transistors) are used as switches Sw101 to Sw106. However, the present invention is not limited to these, and other equivalent functional products may be adopted.

The conduction switching unit 140 includes transistors Q132, Q142, switches Sw121, 122, and resistors Rc111, 112, 121, 122. The conduction switching unit 140 is the anode (anode or input terminal) of the LED of the jth stage (j is an integer of 2 or more and less than N) counted from the feeding end 150A of the LED row according to the control by the drive control unit 120 described below. ) And the feeding end 150A are switched to a conductive state or a non-conducting state.
In other words, the continuity switching unit 140 conducts or does not conduct the LED between the feeding end 150A of the LED row and the LED in the jth stage counting from the feeding end 150A according to the control by the drive control unit 120. Switch to the state. It goes without saying that the number and location of switching non-conduction are not limited to these explanations, and can be increased or decreased as needed.

The drive control unit 120 includes an AD converter (ADC) 121 for input voltage measurement, a control microprocessor unit (MPU) 122, a DA converter (DAC) 123 for current value setting, and a switch control unit 124.

The control MPU 122 is a computer equipped with a CPU, a memory, a program memory, etc., and acquires the voltage value of the pulsating current Vo rectified by the full-wave rectifier FR1 at predetermined time intervals via the ADC 121, and internally. Pulsating current Vo waveform information (information associated with a voltage value and a time indicating the voltage value) is stored in the memory. The predetermined time may be, for example, a time during which 16 to 128 voltage values, preferably 32 to 64 voltage values can be sampled in one AC input cycle. Further, assuming that the waveform information to be accumulated is one waveform information in one pulsating current cycle, it is sufficient to accumulate two or more latest waveform information from the present time. Although not limited in this embodiment, the control MPU 122 constantly accumulates, for example, the latest 4 to 16 waveform information, and the old waveform information is discarded each time.
It should be noted that these MPU performances are low-priced and low-speed MPUs at the time of filing of the present application, and as described above, it is assumed that the processing performance is such that the system does not become unstable and does not oscillate.

The control MPU 122 predicts the subsequent pulsating flow waveform from the value (instantaneous voltage value) of the pulsating current Vo acquired via the ADC 121 at the present time based on the accumulated waveform information. Based on this predicted pulsating current waveform, the control MPU 122 controls the switch control unit 124 to control the switches Sw101 to Sw106 in the constant current drive circuit 130, respectively, and the transistors Q11, Q12, Q13-1, and Q13-2. , Q14, and Q15 are to be operated, and the current values I11, I12, I13-1, I13-2, I14, and I15 flowing through these transistors via the DAC123 are set. At this time, the control MPU 122 outputs the DAC 123 so that the current values I11, I12, I13-1, I13-2, I14, and I15 fall within the set range according to the voltage value (instantaneous voltage value) acquired via the ADC 121. To adjust the current value.

Next, the LED drive control method by the control MPU 122 will be described based on the LED drive method 110 shown in FIG. 1A.

First, the control MPU 122 performs pulsating current Vo and transistors Q11, Q12, Q13-1, Q13 via the ADC 121 at predetermined time intervals (for example, sampling 32 to 64 voltage values for each AC input cycle). Calculated from the voltage value generated in Rs15 by the current flowing through -2, Q14, and Q15. The acquired value is stored in the control MPU 122 as waveform information. The control MPU 122 sequentially (but is not limited to, the latest 4 to 16 waveform information from the present time) leveling the accumulated waveform information to reduce the influence of noise, and then refers to the value.

In steps 1 to 5 described below, in the LED driving method 110, the LED driving method by the control MPU 122 when the voltage of the pulsating current Vo rises from the control reference point (the point where the voltage value of the pulsating current Vo becomes the minimum). Will be explained.

(Step 1)
The MPU 122 measures the Vo value and the current value flowing through Q11 to Q15 with the ADC at predetermined time intervals, and closes Sw101 when it recognizes the control reference point, for example, when the voltage value of Vo becomes the minimum. Sw opens, and the DAC 123 outputs a voltage obtained by adding (Rs11 + Rs12 + Rs13 + Rs14 + Rs15) × I11 to the VGS standard value of Q11 when a preset current of I11 flows, and then the ADC measurement value of Vs is Vs = Rs15 × I11. The control is started so as to become.

(Step 2)
The MPU 122 learned from Vo · Vs and accumulated information that I11 began to flow in Q11 via LEDs (D11 to D14), and added (Rs11 + Rs12 + Rs13 + Rs14) × I11 to the VGS standard value of Q1 when the current I11 flows. The voltage value is set as the initial DAC value, and the DAC output is adjusted so that Vs = Rs15 × I11 indicating that I11 is a predetermined value.
Around this time, Sw102 is closed and set so that current also flows in Q12.

(Step 3)
The MPU 122 learns from Vo, Vs, accumulated information, etc. that I12 has started to flow in Q12 via LEDs (D11 to D17), and sets the DAC initial value to the VGS standard value of Q12 when a current of I12 flows (Rs12 + Rs13 + Rs14 + Rs15). After outputting the voltage to which × I12 is added, the DAC output is adjusted so that I12 becomes Vs = Rs15 × I12, which is a predetermined value, and before and after that, Sw101 is opened, Sw103 and Sw104 are closed, and Q13-1 and Set so that current flows in Q13-2.

(Step 4)
The MPU 122 opens Sw102 when it learns that I13-1 has started to flow to Q13-1 via LEDs (D11 to D19) from Vo, Vs and accumulated information, and Q13-1 when a current of I13-1 flows. The voltage obtained by adding (Rs13 + Rs14 + Rs15) × I13 to the VGS standard value of is output from the DAC123, and then the DAC output is adjusted so that I13 becomes Vs = Rs15 × I13 which is a predetermined value.
At the same time, Sw121 is closed, Sw103 is opened, Q13-2 is guided, and a current I13-2 is passed through LEDs (D13 to D1b) to Q13-2. Around this time, Sw105 is closed and set so that current flows through Q14. Since I13-1 = I13-2 = I13, the control content of the MPU 122 that controls the DAC output regardless of whether I13-1 flows through Q13-1 or I13-2 flows through Q13-2. There is no change.

(Step 5)
The MPU 122 predicts the voltage waveform of Vo from Vo, Vs and accumulated information, and if it predicts that Vo does not reach a value at which I14 can flow to Q14 via LEDs (D12 to D1b), Vo is sharp. The prediction / judgment is continued until the value is reached and the voltage value starts to decrease. At this time, it goes without saying that the DAC output is adjusted so that I3 becomes Vs = Rs15 × I3, which is a predetermined value.
If it is predicted that Vo will reach a value at which I14 can be passed through Q14 via LEDs (D12 to D1b) in the prediction of the voltage waveform of Vo, the time point at which the current I14 is passed through Q14 is set and the time point is reached. When it is determined that the current has been determined, Sw121 is opened, Sw122 is closed, Q132 is cut off, Q142 is in a conductive state, and a current I14 flows from 150A via Q142 to Q14 via LEDs (D12 to D1b). The voltage obtained by adding (Rs14 + Rs15) × I14 to the VGS standard value of Q14 at the time is output from the DAC123, and the DAC output is adjusted so that I14 becomes Vs = Rs15 × I14 which is a predetermined value. Further, Sw106 is closed and Sw103 is opened to enable Q15 to operate.

(Step 6)
The MPU 122 predicts the voltage waveform of Vo from Vo, Vs and accumulated information, and if it predicts that Vo does not reach a value at which I15 can flow to Q15 via LEDs (D11 to D1b), Vo is sharp. This operation is continued until the value is reached and the voltage value starts to decrease, and the DAC output is adjusted so that I14 becomes Vs = Rs15 × I14, which is a predetermined value.
In the prediction of the voltage waveform of Vo, when it is predicted that Vo will reach a value at which I15 can be passed through Q15 via LEDs (D11 to D1b), the time point at which the current I15 is passed through Q15 is set, and the time point is reached. When it is determined that Sw122 is opened and Q142 is cut off, the current I15 is started to flow through all the LEDs (D11 to D1b) to Q15, and the voltage obtained by adding Rs15 × I15 to the VGS standard value of Q15 when the current I15 flows. Is output from the DAC 123, and then the DAC output is adjusted so that I15 becomes Vs = Rs15 × I15, which is a predetermined value, and the MPU 122 continues to predict the voltage waveform of Vo from Vo, Vs and accumulated information, and Vo. Continues to operate until the peak value is reached.

Then, after the pulsating current Vo reaches the peak value, the voltage decreases, but at that time, the operation in the reverse order of the above steps is performed.

In the above example, in (step 4), it is known that the current I13-1 flows out to the LEDs (D11 to D19), and the Sw121 is operated to conduct the Q132 so that the current flows through the LEDs (D13 to D1b). Although it is controlled, Q13-1 can be deleted by directly operating Sw121 by predicting the voltage Vo.

Further, in the above control method, when the allowable input voltage range is widened, the power consumption also fluctuates accordingly, but the fluctuation of the power may be suppressed by increasing or decreasing the current flowing according to the voltage.

By repeating each step in this way, the LED drive circuit 110 turns on / off each LED in the LED row. Further, the LED drive circuit 110 appropriately turns on / off the individual LEDs in the LED row regardless of whether the predicted peak value of the pulsating current Vo is higher or lower than the reference value. This makes it possible to turn on all the LEDs D11 to D1b at any timing within one cycle of the pulsating current, and eliminate the LEDs that do not light at all within the cycle.

Based on the above explanation, the number of LEDs in the LED row is N (N is an integer of 3 or more), and the LED that is switched on / off in order to avoid non-lighting in the pulsation cycle is the LED row. It is easy for a person skilled in the art to have an arbitrary number of LEDs whose total number does not exceed N from both ends of the LED, and to arbitrarily design the number of drawer ends and the drawer positions among the LEDs in the LED row. You can understand it.

In this case, the LED drive method is an LED train having a feeding end at one end to which a full-wave rectified pulse flow is input, and has N LEDs (N is an integer of 3 or more) connected in series with each other. The LED row includes a conduction switching unit that switches an arbitrary number of LEDs from both ends of the LED row, each of which does not exceed N in total, and the conduction switching unit responds to the (instantaneous) voltage value of the pulsation flow. , The continuity of the LED between the feeding end and the LED in the jth stage (j is an integer of 2 or more and less than N) counting from the feeding end, and the kth stage (k is j) counting from the feeding end. It is controlled to switch between the continuity with the LED from the Nth stage (an integer whose total is less than N) to the Nth stage.

Further, if the technical concept of the present invention is extended based on the above description, although wiring becomes complicated, when conducting between LED terminals, one end is not fixed to the feeding end and any LED is conducted to conduct the LED. It goes without saying that the same effect as above can be obtained even if the number is controlled, and the same effect can be easily obtained even if the number of drawer ends and the drawer position are arbitrarily designed among the LEDs in the LED row. You can understand it.
Further, instead of using a plurality of drive circuits, it is determined whether or not a predetermined current can flow in the LED train according to the peak value of the input pulse flow, and the number of LED trains connected to the end of the drive circuit is determined. It is easy to understand that the same effect can be obtained with a single drive circuit by controlling the number of LEDs that light up by preparing the required number of functions to conduct conduction between LEDs and controlling this. Let's go.
Of course, it is also possible to make the LEDs conductive by using a plurality of drive circuits by the same control as the above-mentioned control method.

Further, the LED driving method includes a plurality of extraction ends provided in the LED row, a plurality of transistors connected to the plurality of extraction ends, and a plurality of switches connected to each of the plurality of transistors. The continuity switching unit and the drive control unit that controls the switch may be further included, and the drive control unit controls the plurality of switches according to the instantaneous voltage value of the pulsating flow of the plurality of transistors. The current flowing through each may be controlled.

(Other variations of LED drive current digital control method)
With reference to FIG. 1B, other variations of the digital control method of LED drive current are shown. Devices, elements, and the like having the same member numbers as those in FIG. 1B in FIG. 1B basically have the same operation functions (even if the operation mechanisms are the same, the required specifications may differ. obtain).

The outline of the LED driving method 115 shown in FIG. 1B is as follows. The MPU in FIG. 1B is a series of "DAC-> constant current circuit->ADC-> error calculation" using the ADC for the pulsating current V ₀ in which the AC input is full-wave rectified by the bridge diode FR1 at predetermined time intervals. Negative feedback control operation is always performed. It is assumed that stability is ensured in this operation, and in this description, the values of I11 to I15 and Rs15 are set in advance, and the characteristics of Q15 are known. The operation will be described in detail with reference.

(Step 1)
The MPU 122 measures the value of Vo, the current waveform flowing through Q15, etc. with the ADC at predetermined time intervals as the voltage value of Rs15, and closes Sw101 when recognizing the control reference point, for example, the time when Vo becomes the minimum voltage. , And the other Sw is opened, and the voltage obtained by adding Rs15 × I11 to the VGS standard value of Q15 when the preset current of I11 flows is output to the DAC123, and then the value of Vs becomes Vs = Rs15 × I11. Start control so that it becomes.

(Step 2)
When the MPU 122 recognizes that I11 flows through Q15 via LEDs (D11 to D14) from Vo · Vs and accumulated information, it calculates the voltage value obtained by adding Rs15 × I11 to the VGS standard value of Q15 when the current I11 flows. It is output as a DAC initial value, and then the DAC output is adjusted so that Vs = Rs15 × I11, which is a value set by I11.

(Step 3)
When the MPU 122 recognizes that I12 flows through the LED (D11 to D17) through the LED (D11 to D17) from Vo, Vs, accumulated information, etc., it opens Sw101, closes Sw102, and sets the DAC setting value to I12, which is the VGS standard of Q15. A voltage obtained by adding Rs15 × I12 to the value is output, and then the DAC output is controlled so that I12 becomes Vs = Rs15 × I12, which is a predetermined value.

(Step 4)
When the MPU 122 learns from the Vo, Vs and accumulated information that I13_1 flows through the LED (D11 to D19 to Q15, it opens Sw102, closes Sw103, and further sets the VGS standard value of Q15 to the VGS standard value when the current I13_1 flows. The voltage to which × I13_1 is added is output from the DAC, and then the DAC output is controlled so that Vs = Rs15 × I13_1, which is the value set by I13_1.

(Step 5)
When the MPU 122 learns that I13_1 flows through the LED (D11 to D19) via the LED (D11 to D19) from Vo, Vs and accumulated information, it closes Sw122, opens Sw103, and conducts a current to Q15 through the path of Sw122 to LED (D13 to D1b). The voltage obtained by adding Rs15 × I13_2 to the VGS standard value of Q15 when the current I13_2 flows so that I13_2 flows is output from the DAC, and then the DAC output is made so that Vs = Rs15 × I13_2, which is the value set by I13_2. To control.

(Step 6)
The MPU 122 predicts the voltage waveform of Vo from Vo, Vs and accumulated information, and if it predicts that Vo does not reach a value at which I14 can flow to Q15 via LEDs (D12 to D1b), Vo is sharp. The prediction / judgment is continued until the value is reached and the voltage value starts to decrease. Needless to say, the MPU 122 controls the DAC output so that Vs = Rs15 × I13_2, which is a value set by I13_2.
When the MPU 122 predicts that the voltage waveform of Vo reaches a value at which I14 can be passed through Q15 via LEDs (D12 to D1b), a time point at which current I14 is passed through Q15 is set, and Vo reaches that time point. Then, Sw122 is opened, Sw121 is closed, and the voltage obtained by adding Rs15 × I14 to the VGS standard value of Q15 when the current I14 flows so that the current I14 flows through the Sw121 to LED (D2 to D1b). Is output from the DAC, and then the DAC output is controlled so that Vs = Rs15 × I14, which is the value set by I14.

(Step 7)
The MPU 122 predicts the voltage waveform of Vo from Vo, Vs and accumulated information, and when Vo predicts that it does not reach the value at which I15 can flow through Q15 via LEDs (D11 to D1b), Vo reaches the peak value. The operation is continued until the voltage value starts to decrease.
Further, when the voltage waveform of Vo is predicted to reach a value at which I15 can be passed through Q15 via LEDs (D11 to D1b), the MPU 122 sets a time point at which the current I15 is passed through Q15, and Vo is set at that time point. When it is determined that the voltage has been reached, Sw121 is opened, the current I15 is started to flow through the LEDs (D11 to D1b), and the voltage obtained by adding Rs15 × I15 to the VGS standard value of Q15 when the current I15 flows is applied from the DAC. After that, the DAC output is controlled so that Vs = Rs15 × I15, which is the value set by I15.
The MPU 122 continues to predict the voltage waveform of Vo from Vo, Vs and accumulated information, and continues to operate until Vo reaches the peak value.

After the pulsating current Vo reaches the peak value, the voltage decreases, but at that time, the above-mentioned reverse operation is performed.
In this example, in consideration of the fact that the number of wires increases in practical use and the work becomes complicated, Sw101 to Sw103 and Sw121 to 122 all have one end in common, but in terms of the operating principle, it is inevitable that one end of Sw is common. Needless to say, the same effect can be obtained by connecting different LEDs as needed.
When the allowable voltage range is widened, the power consumption also fluctuates accordingly, but the current flowing according to the voltage may be reduced to suppress the fluctuation of the power.

[ Second Embodiment ] <Analog control method of LED drive current>
FIG. 2 is a configuration example of the LED driving method 210 according to the second embodiment of the present invention. It is a so-called full analog control method, and it is relatively more difficult to implement than the first embodiment described above (note that it is a digital system that takes into consideration oscillation suppression in full digital control and implementation difficulty of the full analog control method. The analog mixed control method is the third embodiment described later).

As shown in FIG. 2, the LED drive control method 210 is a constant current drive circuit 230 having a full-wave rectifier FR1, an LED train (exemplarily consisting of 11 LED trains from D21 to D2b), a plurality of transistors, and the like. , And a continuity switching unit 240.

The LED drive circuit 210 includes an operational capacitor Op21, constant current drive transistors Q21 to Q26, switch transistor control transistors Q221, Q231, Q241, switch transistor drive transistors Q230, Q240, Q250, and switch transistor (P channel MOSFET). ) Q261, Q262, resistors R21 to R26, Rs21 to Rs26, Rg11, Rg22, etc., which constitute a constant current drive circuit 230 for driving the LED trains (D21 to D2b) with a constant current as shown in FIG. do. Each transistor is a MOSFET, but the number is not limited to this, and the LED in one row is not limited to this. The connection form is possible, and these are described as one column as a representative.

As shown in FIG. 2, as the transistor for driving the LED train (D21 to D2b), Q21 to Q26, Q221, Q231, Q241, Q230, Q240, and Q250 are exemplified, but the transistor is limited to this. It is not something that will be done. Further, the LED row includes 11 LEDs (D21 to D2b) and is provided with drawer ends 251 to 253 and 250B, but is not limited to this number.

In steps 1 to 7 described below, the LED driving method when the voltage of the pulsating current Vo rises from the reference point (for example, the point where the voltage value of Vo becomes the minimum) in the LED driving circuit 210 will be described.

Here, Q21 to Q26 operate as a constant current source that also serves as a switch.

Vref × (Rf2 + Rf1) / Rf1
= (Rs21 + Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I21
= (Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I22
= (Rs23 + Rs24 + Rs25 + Rs26) × I23
= (Rs24 + Rs25 + Rs26) × I24
= (Rs25 + Rs26) × I25
= Rs26 × I26

It works to satisfy the formula.
Here, I21 <I22 <I23 <I24 <I25 <I26.

Further, the switches Q261 and Q262 that conduct the LEDs (D21 to D22) operate by passing a current I261 or I262 through the Q230, Q240, and Q250. Further, Q221, Q231, and Q241 control MOSFETs Q230, Q240, and Q250 that control switches Q261 and Q262.
The characteristics of LEDs and other MOSFETs, including MOSFETs used for the current values of I21 to I26, are known, and on the premise of using these, Rs21 to Rs26, I21 to I26, Rc211 to Rc212, Rc221 to Rc222 , I261 to I262 have been set, and the operation of the LED drive circuit 210 will be described assuming that the circuit operates stably.

(Step 1)
When the value of the pulsating current Vo rectified by the bridge diode FR1 is low and no current flows through the LED train, the arithmetic amplifier Op21 raises the output Vop of the arithmetic amplifier Op21 in order to allow current to flow through the MOSFET (Q21). It is low and no current flows in the LED row.
At this time, a voltage larger than the value obtained by adding (Rs21 + Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I21 to the VGS value of Q1 when the current I21 flows is applied to the gate of Q21 to enable Q21 to operate. In addition, Q22 to Q26 can also operate because a voltage larger than the value obtained by adding each source voltage to the VGS value when a current is passed through each MOSFET is applied to Q22 to Q25 that operate with a current larger than I21. However, Q230, Q240, and Q250 to which the same gate potential is applied via the resistors Rg11, Rg21, and Rg31 use the gate potentials of the preceding stages Q22, Q23, and Q24 as the resistances Rg02 / Rg03, Rg12 / Rg13, and Rg22 / Rg23. Since the Q221, Q231, and Q241 applied via the operation operate to lower the gate potentials of the Q230, Q240, and Q250 and suppress the operation, the switches Q261 and Q262 remain open.
The values of Rg11, Rg21, Rg31 and Rg02 / Rg03, Rg12 / Rg13, Rg22 / Rg23 do not affect the operation of Q22 to Q25, and the influence on the circuit operation is ignored by setting each value to operate. can. The resistance values and ratios of Rg11, Rg21, Rg31, Rg02 / Rg03, Rg12 / Rg13, and Rg22 / Rg23 are sequentially determined as values that do not interfere with the operation in consideration of the characteristics of each MOSFET.

(Step 2)
After the pulsating current Vo gradually rises and the voltage of I21 reaches the voltage flowing through the LEDs (D21 to D24) to Q21, the LEDs D21 to D24 light up.
A voltage obtained by adding (Rs21 + Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I21 to the VGS value when the current I21 is passed is applied to the gate of Q21, and the VGS when the current is passed through each MOSFET to Q22 to Q25 which operate at a current larger than I21. A voltage larger than the value obtained by adding each source voltage to the value is applied, and Q22 to Q25 can also operate, but no current flows through D25 to D2b and Q22 to Q26, and Q221, Q231, and Q241 operate. Q230, Q240, Q250, Q261, and Q262 are in the same state as in (step 1) in the cutoff state.

(Step 3)
After the pulsating current Vo further rises and the voltage of I22 reaches the voltage flowing through the LED rows (D21 to D27) to Q22, the LED rows (D21 to D27) are lit.
A voltage VG2 = VGS2 + (Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I22 obtained by adding (Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I22 to the VGS value when the current I22 is passed is applied to the gate of Q22.
VGS1 = {VGS2 + (Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I22} × R26 / (R25 + R26)-(Rs22 + Rs23 + Rs24 + Rs25 + Rs26) × I22 is applied to the gate of Q21. R25 and R26 are set so that Q21 does not operate, and when I22 flows, Q21 does not operate and I21 does not flow.
As a result, no current flows through Q21, Q23 to Q26, and the LED rows (D28 to D2b), and Q221, Q231, Q241, Q230, Q240, Q250, Q261, and Q262 remain in the same state as before.

(Step 4)
After the pulsating current Vo further rises and the voltage of I23 reaches the voltage flowing through the LED rows (D21 to D29) to Q23, the LED rows (D21 to D29) are lit.
A voltage VG3 = VGS3 + (Rs23 + Rs24 + Rs25 + Rs26) × I23 obtained by adding (Rs23 + Rs24 + Rs25 + Rs26) × I23 to the VGS value when the current I23 is passed is applied to the gate of Q23.
VGS2 = (VGS3 + (Rs23 + Rs24 + Rs25 + Rs26) × I3) × (R25 + R26) / (R24 + R25 + R26)-(Rs23 + Rs24 + Rs25 + Rs26) × I3 is applied to the gate of Q22. R24 is set so that Q22 does not operate, and Q22 is set to a value that does not operate when I23 flows. Since the VGS of Q21 is lower than the VGS of Q22, Q21 also does not work. In this way, Q22 is in the non-operating state when Q23 is operating, but at this time, Q221 is also in the shutoff state, and when Q22 is operating, Q221 is also in the operating state, and Rg02 is so as not to affect the operation of Q22 and Q23. And the value of Rg03 are determined. Further, the value of Rg11 is set so that the Q230 is in the non-operating state when the Q221 is operating, the Q230 is operating when the Q221 is not operating, and the operation of the Q23 is not affected.
As a result, when I23 flows through Q23, Q221 becomes inactive, the voltage drop of Rg11 disappears, Q230 operates, current I261 flows, voltage is generated in Rc211 and the switch consisting of P channel MOSFET (Q261) closes. Conduction between the LEDs (D21 to D22). At this point, no current is flowing through Q21 to Q22, Q24 to Q26, and D2a to D2b.
Then, Q230, Q231, and Q241 continue to operate, and Q221, Q240, and Q250 do not operate.

(Step 5)
When Q261 of the switch is closed, the space between D21 and D22 becomes conductive. Here, the LED rows D21 to D29 and the LED rows D23 to D2b have the same number of LED stages, and by setting the values of the currents I23 and I24 to the same value or so that the difference between them is not large, the voltage drop of the LED train is equivalent. As a value, a current of I24 is passed through the LED (D23 to D2b) via the switch Q261 at the same value of the pulse flow Vo as in (step 4) to light the LED (D23 to D2b). A voltage VG4 = VGS4 + (Rs24 + Rs25 + Rs26) × I24 obtained by adding (Rs24 + Rs25 + Rs26) × I24 to the VGS value when the current I24 is passed is applied to the gate of Q24. VGS3 = (VGS4 + (Rs24 + Rs25 + Rs26) × I24) × (R24 + R25 + R26) / (R23 + R24 + R25 + R26)-(Rs24 + Rs25 + Rs26) × I24 is applied to the gate of Q23. R23 is set so that Q23 does not operate, and Q23 is set to a value that does not operate when I24 flows. The VGS of Q22 and Q21 is lower than the VGS of Q23, and Q21 and Q22 do not operate either. In this way, when Q24 is operating, Q23 is in a non-operating state, but at the same time, Q231 is also in a shut-off state, and when Q23 is operating, Q231 is also in an operating state, and the values of Rg12 and Rg13 are set so as not to affect the operation of Q23. Further, Q240 is set to be in a non-operating state during Q231 operation, but at this time, the value of Rg21 is set so as not to affect the operation of Q24.
As a result, when I24 flows through Q24, Q231 becomes inactive, the voltage drop of Rg21 disappears, Q240 operates, current I261 flows, a potential is generated in Rc211 and the switch consisting of P channel MOSFET (Q261) is closed. Since it remains as it is, the LED (D21 to D22) continues to conduct electricity. No current is flowing through Q21 to Q23, Q25 to Q26, and D21 to D22.
Q240 and Q241 continue to operate, while Q221, Q231, Q230 and Q250 do not.

(Step 6)
After the pulsating current Vo further rises and the voltage at which I25 can flow to Q25 via the LED trains (D22 to D2b) is reached, the LED trains (D22 to D2b) light up.
A voltage VG5 = VGS5 + (Rs25 + Rs26) × I25 obtained by adding (Rs25 + Rs26) × I25 to the VGS value when the current I25 is passed is applied to the gate of Q25.
VGS4 = (VGS5 + (Rs25 + Rs26) × I25) × (R23 + R24 + R25 + R26) / (R22 + R23 + R24 + R25 + R26)-(Rs25 + Rs26) × I25 is applied to the gate of Q24. R22 is set so that Q24 does not operate, and Q24 is set to a value that does not operate when I25 flows. The VGS of Q23, Q22, and Q21 is lower than the VGS of Q24, and Q21 to Q23 do not operate either. In this way, Q24 is in the non-operating state when Q25 is operating, but at this time, Q241 is also in the shutoff state, Q241 is also in the operating state when Q24 is operating, and the values of Rg22 and Rg23 are set so as not to affect the operation of Q24 and Q25. stipulate. Further, the Q250 is set to the non-operating state when the Q241 is operating, and the value of Rg31 is set so that the Q250 operates when the Q241 is not operating and does not affect the operation of the Q25.
As a result, when I25 flows through Q25, Q241 becomes inactive, the voltage drop of Rg31 disappears, Q250 operates, current I262 flows, voltage is generated in Rc221, the switch consisting of P channel MOSFET (Q262) closes, and the LED. Conduction occurs between (D21). No current flows through D21, and Q21 to Q24, Q26, Q221, Q231, Q241, Q230, and Q240 do not operate.

(Step 7)
After the pulsating current Vo further rises and the voltage at which I26 reaches a voltage that can be passed through the LED rows D21 to D2b to the Q26, all the LEDs in the LED rows D21 to D2b are turned on.
A voltage VG6 = VGS6 + Rs26 × I26 obtained by adding Rs26 × I26 to the VGS value when the current I26 is passed is applied to the gate of Q26.
VGS5 = (VGS6 + Rs26 × I26) × (R22 + R23 + R24 + R25 + R26) / (R21 + R22 + R23 + R24 + R25 + R26) -Rs26 × I26 is applied to the gate of Q25. R21 is set, and Q25 is set to a value that does not operate when I26 flows. The VGS of Q24 to Q21 is lower than the VGS of Q25, and Q21 to Q24 do not operate either.
When Q25 stops working, Q250 also stops working and I262 does not flow, so there is no potential difference between both ends of Rc221, and the switch consisting of P-channel MOSFET (Q262) opens both ends of D21, so D21 also lights up and all LEDs from D21 to D2b. Lights up. Q21 to Q25, Q221, Q231, Q241, Q230, Q240, and Q250 do not operate.

After the pulsating current Vo reaches the peak value, the voltage decreases, but at that time, the operation in the reverse order of the above step is performed.

The full analog drive method according to the second embodiment has the circuit configuration and the peculiar operating principle described above, whereby the same effect as that of the first embodiment can be obtained.

[ Third Embodiment ] <Digital-to-analog mixed control method of LED drive current>
FIG. 3 is a circuit configuration example of the LED drive circuit 310 according to the third embodiment of the present invention. It is a so-called hybrid circuit. The significance of adopting such a hybrid configuration is to achieve the stability of the system in a fully digital configuration from another point of view. In other words, the stability of the system, which was performed in full digital, will be borne by the analog circuit part in the hybrid configuration. As a result, the power of the CPU (MPU) required for ensuring the stability of the system is released, and the surplus can be allocated to accurate peak prediction, state prediction, and switch control.

As shown in FIG. 3, the LED drive method 310 includes a full-wave rectifier FR1, a drive control unit 320, a constant current drive circuit 330 having a plurality of transistors, and a conduction switching unit 340. The LED drive method 310 according to the present embodiment is not a simple combination of the LED drive method 110 according to the first embodiment and the LED drive method 210 according to the second embodiment, but rather the LED drive according to the first embodiment. It has the characteristic that a part of the method 110 is replaced with an analog circuit configuration, or an analog drive method is added to the LED circuit 110.

In steps 1 to 7 described below, the LED driving method when the voltage of the pulsating current Vo rises from the reference point (for example, the point where the value of Vo becomes the minimum) in the LED driving method 310 will be described.

Here, the MPU 322 measures the voltage waveform of the pulsating current Vo rectified by the bridge diode FR1 at a predetermined time using the ADC 321 and controls the switch after grasping the operating states of Q31 to Q36.
The current values of I31 to I36 are Vref × (Rf32 + Rf31) / Rf31 = (Rs31 + Rs32 + Rs33 + Rs34 + Rs35 + Rs36) × I31 = (Rs32 + Rs33 + Rs34 + Rs35 + Rs36) × I32 = (Rs33 + Rs34 + Rs35 + By setting I31 to I36 and Rs31 to Rs36 so as to satisfy the requirements, it is possible to eliminate the need to individually set the DAC output for each of I31 to I36, reduce the complexity of processing and the fluctuation of processing time, and simplify the control. It is also possible to appropriately set Rs31 to Rs36 to approximate the current waveform flowing in the LED train to a sine wave and reduce harmonics. Here, a very high resistance that does not affect the operation of other circuits is connected between the gate and the source of Q31 to Q36 (not shown in FIG. 3 because it is complicated), and is connected to the gate. When the switch is open, the MOSFET is cut off and does not operate.
The values of I1 to I6 and the values of Rs31 to Rs36 have already been determined-therefore, Vref, Rf31, and Rf32 have also been determined-the characteristics of the MOSFET (Q31 to Q36) have also been clarified. The following steps will be described assuming that the current circuit system is stable and the stability of the control system is ensured.

(Step 1)
The MPU322 measures the pulsating currents Vo and Vs (current values flowing in Q31 to Q36) with the ADC at predetermined time intervals, and recognizes the control reference point-for example, the time when the Vo value becomes the minimum-and the elapsed time. At the same time, the subsequent Vo waveform, LED row continuity start voltage, etc. are predicted based on the current and past measurement information. The measured voltage of pulsating current Vo is low and Q31 to Q35 do not operate, but MPU322 closes Sw302 and Sw311, opens other Sw312 to Sw316, Sw301, SW303 to Sw306, Sw321 and Sw322, and can operate Q31 and Q32. Make it a state.
Further, the value of Ri32 is set here.

(Step 2)
After the pulsating current Vo gradually rises and I31 can flow to Q31 via the LED rows D31 to D34, the Q31 operates and the current I31 flows through the LED rows D31 to D34 to light up.
The value of Vo is still low, no current flows through D35 to D3b, and Q32 to Q36 do not operate either.
During the operation of Q32, the voltage VG2 = VGS2 + (Rs32 + Rs33 + Rs34 + Rs35 + Rs36) × I32 is applied to the gate VG2 of Q32 by adding (Rs32 + Rs33 + Rs34 + Rs35 + Rs36) × I32 to the VGS value VGS2 when the current I32 flows. Rs32 + Rs33 + Rs34 + Rs35 + Rs36) × I32} × Ri32 / (Ri31 + Ri32)-(Rs32 + Rs33 + Rs34 + Rs35 + Rs36) × I32 are added, but VGS2, Rs32 to Rs36, and I32 are known, so Q31 can be obtained in this VGS1 value range. And tentatively determine the value of Ri31, and prevent Q31 from operating when I32 flows.
The MPU322 detects that Q31 is operating and I31 is flowing from the value of Vs and the Vo value at that time.

(Step 3)
After the pulsating current Vo rises and I32 can flow to Q32 via the LEDs (D31 to D37), the current I32 flows through Q32 and the LED rows D31 to D37 light up.
The MPU322 recognizes that Q32 operates and I32 is flowing from the value of Vs, measures the value of Vo at which Q32 starts operating, opens Sw302 and Sw311, closes Sw303 and Sw312, and stops the operation of Q31. , Q32 and Q33 can be operated. Since the switch is open, Q31 and Q34 to Q36 do not work.
During Q33 operation, the voltage VG3 = VGS3 + (Rs33 + Rs34 + Rs35 + Rs36) × I33 obtained by adding (Rs33 + Rs34 + Rs35 + Rs36) × I33 to the VGS value when the current I33 flows is applied to the gate VG3 of Q33, and VGS2 = {VGS3 + × I33} × Ri32 / (Ri31 + Ri32)-(Rs33 + Rs34 + Rs35 + Rs36) × I33 is added, but since VGS3, Rs33 to Rs36, and I33 are known, Q32 does not work with this VGS2 and does not contradict the previous value. The value is tentatively determined so as not to contradict the previous value within the range that Ri31 can take.

(Step 4)
After the pulsating current Vo further rises and the I33 can flow to the Q33 via the LED rows D31 to D39, the current I33 flows through the Q33 and the LED rows D31 to D39 light up.
When MPU322 recognizes that Q33 operates and I33 is flowing from the value of Vs together with the value of Vo at which Q33 starts to operate, it opens Sw303 and Sw312, closes Sw304 and Sw313, and suppresses the operation of Q31 to Q32. Enable Q33 and Q34 to operate.
During Q34 operation, the voltage VG4 = VGS4 + (Rs34 + Rs35 + Rs36) × I34 obtained by adding (Rs34 + Rs35 + Rs36) × I34 to the VGS value when the current I34 flows is applied to the gate VG4 of Q34, and VGS3 = {VGS4 + (Rs34 + Rs36) + Rs35 to Q33. × I34} × Ri32 / (Ri31 + Ri32)-(Rs34 + Rs35 + Rs36) × I34 is applied, but since VGS4, Rs34 to Rs36, and I34 are known, Q33 does not operate in this VGS3 and is consistent with the previous value. The value is tentatively determined so as not to contradict the previous value within the range that Ri31 can take.

(Step 5)
The MPU322 predicts the Vo voltage waveform from the current Vo value and the elapsed time from the reference point, and closes the SW321 when it predicts that the current I34 can flow through the LED rows D33 to D3b, and is a switch composed of a P-channel MOSFET (Q332). Is operated to conduct current between the LED rows D31 to D32, and the LED rows D33 to D3b are turned on.
Since the number of LED stages of the LED rows D31 to D39 and the LED rows D33 to D3b are the same, the difference between the currents I33 and I34 is set so as not to be large, or if Rs33 is set to 0Ω and I33 = I34, the voltage drop of the LED row It is also possible to close Sw321 and operate a switch consisting of Q332 to pass the current of I34 through the LED rows D33 to D3b to light it without making a prediction.
The MPU322 grasps that I34 is flowing and the Vo value at that time by reading the value of Vs.
After that, MPU322 opens Sw304 and Sw313, closes Sw305 and Sw314, stops the operation of Q31 to Q33, and makes Q34 and Q35 operable.
During Q35 operation, the voltage VG5 = VGS5 + (Rs35 + Rs36) × I35 obtained by adding (Rs35 + Rs36) × I35 to the VGS value when the current I35 flows is applied to the gate VG5 of Q35, and VGS4 = {VGS5 + (Rs35 + Rs36) to Q34. × I35} × Ri32 / (Ri31 + Ri32)-(Rs35 + Rs36) × I35 is applied, but since VGS5, Rs34 to Rs36, and I35 are known, Q33 does not operate on this VGS4 and does not contradict the previous values. Tentatively determine the value so that it does not conflict with the previous value within the range that Ri31 can take.

(Step 6)
The MPU 322 predicts the Vo voltage waveform from the current value of the pulsating current Vo, the elapsed time from the reference point, and the like, and predicts whether or not the current I35 can be passed through the LED rows D32 to D3b.
When it is predicted that it is possible, the MPU 322 opens Sw321 and closes Sw322 when it predicts that it is possible, opens a switch consisting of P-channel MOSFET Q332, closes a switch consisting of Q342, and conducts the LEDs (D31) to conduct the LED rows D32 to D3b. Turn on.
Further, the MPU 322 opens Sw305 and Sw314, closes Sw306 and Sw315, stops the operations of Q31 to Q34, and makes Q35 and Q36 operable. The MPU322 grasps that I35 is flowing and the Vo value at that time by reading the value of Vs.
If it is predicted that it will not be possible, the previous state will be maintained.
When Q36 operates, a voltage VG6 = VGS6 + Rs36 × I36 obtained by adding Rs36 × I36 to the VGS value when the current I36 flows is applied to the gate VG6 of Q36, and VGS5 = (VGS6 + Rs36 × I36) × Ri32 / to Q35. (Ri31 + Ri32) -Rs36 × I36 is applied, but since VGS6, Rs36, and I36 are known, Q35 does not operate in this VGS5, and the range does not contradict the previous value and does not contradict the previous value. The value is determined so as not to contradict the previous value within the range that Ri31 can take.

(Step 7)
The MPU 322 predicts the Vo voltage waveform from the current value of the pulsating current Vo, the elapsed time from the reference point, and the like, and predicts whether or not the current I36 can be passed through the LED rows D31 to D3b.
When it is predicted that it is possible, the MPU 322 opens Sw322 when it predicts that it is possible, opens a switch composed of the P channel MOSFET Q342, and passes a current I36 to the LED (D31) to light all the LED rows D31 to D3b.
Further, the MPU 322 opens Sw315, stops the operations of Q31 to Q35, and operates only Q36. (The switches of Q332 and Q342 are open.)
MPU322 confirms that I36 is flowing and the Vo value at that time.
If it is predicted that it will not be possible, the previous state will be maintained.

After the pulsating current Vo reaches the peak value, the voltage decreases, but at that time, the operation in the reverse order of the above step is performed.

In the LED drive method or drive circuit in the above embodiment, the AC power supply is single-phase, and the description has been made on the premise that this is full-wave rectified. However, the present invention is limited to these single-phase two-wire AC. It's not something. It is also possible to apply the LED drive method or drive circuit according to the above embodiment of the present invention on the premise that the three-phase three-wire AC is full-wave rectified to form a pulsating current. The present invention obtains the same effect as the single-phase alternating current in this case as well.

With reference to FIG. 5, an embodiment in a case where the three-phase three-wire alternating current is full-wave rectified to form a pulsating current will be described. FIG. 5A is a full-wave rectifier FR1 for single-phase two-wire alternating current used in the LED drive method or drive circuit described with reference to FIGS. 1A to 3. In the case of full-wave rectifying the three-phase three-wire alternating current to form one embodiment of the present invention, by adopting the full-wave rectifier FR2 as shown in FIG. 5 (B), the present invention (B) shows. The circuit configuration on the right side when viewed from FR2 is the same as the circuit configuration on the right side when viewed from FR1 in the figure (A) (that is, the LED drive method or drive circuit described by pressing three types of FIGS. 1A to 3). can do.

となる。 However, in the case of three-phase full-wave rectification, as shown in FIG. 5C, the pulsating current does not drop to 0V, so the switching point between the pulsating current and the pulsating current starts from the point where the voltage changes from decreasing to increasing. And. In the case of three-phase full-wave rectification, there is a phase difference of 60 degrees, so in the figure (C), the switching point where the voltage changes from decrease to increase is

Will be.

Further, although the brightness of the LED fluctuates, there is no period of extinguishing the LED, and the LED is always lit. Furthermore, by adopting the LED drive circuit according to the embodiment of the present invention using three-phase full-wave rectification, it is possible to continue lighting the LED even when the phase is open or the voltage drops, including the case of partial lighting. It also has an effect.

Although the LED drive method and the drive circuit according to the embodiment of the present invention have been described above based on the specific example, it is easy for a person skilled in the art to realize a lighting device incorporating the LED drive method and the drive circuit. Needless to say, it is.

For all the components described herein (including claims, abstracts, and drawings) and / or for all steps of all disclosed methods or processes, these features are mutually exclusive. Any combination can be used except for the combination of.

Also, each of the features described herein, including claims, abstracts, and drawings, serves the same, equivalent, or similar purpose, unless expressly denied. Can be replaced with alternative features. Therefore, unless expressly denied, each of the disclosed features is merely an example of a comprehensive set of identical or equal features.

Furthermore, the present invention is not limited to any specific configuration of the above-described embodiments. The present invention describes all novel features or combinations thereof described herein (including claims, abstracts, and drawings), or all novel methods or processing steps described, or them. Can be extended to the combination of.

110, 210, 310 LED drive circuit 120, 320 Drive control unit 130, 230, 330 Constant current drive circuit 140, 240, 340 Conduction switching unit 150A, 250A, 350A Supply end 151 to 153, 251 to 253, 351 to 353 Drawer end

Claims (7)

In a series-connected LED train with a feed end as one end, which is driven by a full-wave rectified pulse flow, different locations of the LED train starting from the feed end are connected to different LED drive units. The required LED drive unit is operated according to the instantaneous value of the pulse flow to control the lighting of the LED from the power supply end to the LED drive unit connection location, and the LED terminal at the farthest end when viewed from the power supply end of the LED row. Is connected to the drive unit, and the number of lit LEDs is controlled according to the instantaneous value of the pulsation flow by conducting or short-circuiting between the LED terminals at a preset single number or a plurality of locations of the LED row.
The control of the number of lighting LEDs is
(1) Whether the number of lighting LEDs reached in advance at predetermined time intervals in one AC input cycle or the voltage value of the pulsating current set in advance at predetermined time intervals in one AC input cycle is reached. Monitor the status of any of
(2) When the number of lighting LEDs reaches the preset number, or the voltage value of the pulsating current reaches the preset value,
(2-1) By closing the switch connected between the terminals of the preset number of LEDs in the LED row or the preset number of LEDs according to a plurality of locations, the LEDs between the terminals are turned off.
(2-2) At the same time as the above (2-1), the LED drive unit connected to the farthest end from the feeding end of the LED row is operated to light the LED row.
(2-3) Before and after the operations of the above (2-1) and the above (2-2) , a newly lit LED and a newly turned off LED or an LED that keeps the turned off are generated in the LED row. A LED driving method, wherein each LED in the LED is controlled to light in at least one of a predetermined time intervals in one cycle of the AC input . The LED driving method is
A plurality of drawer ends provided in the LED row, a plurality of constant current drive units connected to the plurality of drawer ends, and a plurality of constant current drive units.
The switch function that operates in synchronization with the operation of the constant current drive unit and is installed in the required part,
A conduction switching unit that conducts the feeding end and the LED end different from the feeding end, which operates by the switch function,
Further includes a control unit that controls the plurality of constant current drive units, and includes a control unit.
The control unit controls the switch and / or the conduction switching unit together with the constant current drive unit so that a current flows through the LED array having a length corresponding to the instantaneous voltage value of the pulsating current, thereby causing the LED array to flow. The driving method according to claim 1, wherein the flowing current is controlled. The LED driving method is
A constant current drive unit including a plurality of drawer ends provided in the LED row, a plurality of transistors connected to the plurality of drawer ends, and a plurality of switches connected to each of the plurality of transistors.
Further includes a conduction switching unit and a drive control unit that controls the switch.
The drive method according to claim 1, wherein the drive control unit controls the plurality of switches according to the instantaneous voltage value of the pulsating current to control the current flowing through each of the plurality of transistors. The drive control unit
By accumulating the latest waveform information of the pulsating current,
Based on the accumulated waveform information, the waveform including the peak value of the pulsating current is predicted from the instantaneous voltage value of the pulsating current.
The driving method according to claim 3, wherein the instantaneous voltage value of the pulsating current is a waveform including the predicted peak value. The drive control unit includes an ADC for input voltage measurement, a switch control unit, a DAC for setting a current value, an ADC for measuring the input voltage, a switch control unit, and a control MPU for controlling the DAC for setting the current value. Including
The switch control unit controls a plurality of switches connected to each of the plurality of transistors and the conduction switching unit.
The ends of the plurality of switches connected to each of the plurality of transistors are connected to the current value setting DAC.
The driving method according to claim 3 or 4, wherein the source of at least one of the plurality of transistors is feedback-connected to the ADC for input voltage measurement. The drive control unit includes an ADC for input voltage measurement, a switch control unit, a DAC for setting a current value, an ADC for measuring the input voltage, a switch control unit, and a control MPU for controlling the DAC for setting the current value. Including
The switch control unit controls at least the continuity switching unit.
A constant voltage control unit that controls a constant voltage for the constant current drive unit is further provided.
The constant voltage control unit is
The input end (+ side) is connected to the current value setting DAC, and
One of the input ends (-side) is grounded via a resistor and the other end is connected to the source of one of the plurality of transistors via a resistor.
The driving method according to claim 3 or 4, wherein one of the output ends is grounded through a resistor and the other end is provided with an operational amplifier connected to the plurality of switches. A lighting device provided with the driving method according to any one of claims 1 to 6.

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