JP2012114236A - Light-emitting diode driving device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make thermal distribution uniform and to make the circuit slim.SOLUTION: The light-emitting diode driving device comprises a first LED 11 having at least one LED element connected with a rectifier circuit 2, a second LED 12 having at least one LED element connected with the first LED 11, a third LED 13 having at least one LED element connected with the second LED 12, first means 21 connected in parallel with the second LED 12 and controlling the amount of electric power to the first LED 11, second means 22 connected in parallel with the third LED 13 and controlling the amount of electric power to the first LED 11 and second LED 12, first current control means 31 for controlling the limitation amount of electric power to the first LED 11 by the first means 21, and second current control means 32 for controlling the limitation amount of electric power to the first LED 11 and second LED 12 by the second means 22. The first current control means 31 and the second current control means 32 are connected in series.

Description

  The present invention relates to a driving device that drives a light emitting diode to light, and more particularly, to a light emitting diode driving device that drives using a AC power source.

  In recent years, light-emitting diodes (hereinafter also referred to as “LEDs”) that can be driven with lower power consumption than incandescent bulbs and fluorescent lamps have attracted attention as light sources for illumination. LEDs are advantageous in that they are small in size and strong in impact resistance, and there is no fear of ball breakage.

  As a power source for such lighting equipment, it is desirable to use an alternating current as a power source such as a household power source. On the other hand, the LED is a DC drive element and emits light only with a forward current. Moreover, the forward voltage Vf of LED currently used frequently for illumination applications is about 3.5V. The LED does not emit light unless Vf is reached, and conversely, if Vf is exceeded, an excessive current flows. Therefore, it can be said that driving by direct current is suitable for the LED.

  In order to meet these conflicting conditions, various LED drive circuits using an AC power source have been proposed (for example, Patent Document 1). Among them, the present applicant has developed an AC multi-stage circuit that drives a multi-stage circuit in which a plurality of LED blocks obtained by connecting a plurality of LED elements in series and connected in series are connected in series by AC full-wave rectification. In this AC multistage circuit, as shown in FIG. 17, an AC power supply 71 is full-wave rectified by a bridge circuit 72 and applied directly to a multistage circuit of an LED block without being smoothed by a smoothing capacitor 73. This AC multistage circuit has the advantages that a large-sized element such as an aluminum electrolytic capacitor that requires high withstand voltage and high capacity characteristics for smoothing is not required, and that no switching power supply is required.

JP 2005-93728 A

  However, in the circuit configuration of FIG. 17, the wiring of some of the switching elements (specifically, the first current detection control means and the second current detection control means) intersect, so that a three-dimensional circuit board such as a multilayer board is used. There is a problem that the circuit pattern becomes complicated, such as the need for wiring. In addition, since the circuit length is relatively long and the width of the conducting wire is narrowed by a more complicated circuit pattern, there is a problem that the heat dissipation of the amount of heat generated by the element is lowered.

  The present invention has been made in view of such a background, and a main object of the present invention is to provide a light-emitting diode driving device that simplifies the circuit wiring pattern and facilitates design while improving heat dissipation. It is in.

Means for Solving the Problems and Effects of the Invention

  In order to achieve the above object, according to the light emitting diode driving device according to the first aspect, a rectifier circuit 2 that can be connected to an AC power source and rectifies an AC voltage of the AC power source, and the rectifier circuit 2 A first LED unit 11 having at least one LED element connected to the second LED unit 12 having at least one LED element connected to the first LED unit 11, and a connection to the second LED unit 12. A third LED unit 13 having at least one LED element, a first means 21 connected in parallel with the second LED unit 12 and for controlling the amount of energization to the first LED unit 11; A second means 22 is connected in parallel with the third LED part 13 and controls the amount of power supplied to the first LED part 11 and the second LED part 12, and a second means for controlling the first means 21. Single current control means 1, a second current control means 32 for controlling the second means 22 includes a said first current control means 31 and the second current control means 32 can be connected in series. Thereby, the first current control means and the second current control means are connected in series, and the wiring does not intersect between them, so that the wiring pattern can be simplified, which is advantageous in terms of the circuit configuration. In particular, the simplification of the wiring pattern also leads to a wider wiring width, and in addition to reducing the electrical resistance of the wiring pattern, heat generated by the element can be dissipated over a wide area, leading to improved heat dissipation.

  Moreover, according to the light-emitting-diode drive device which concerns on a 2nd side surface, said 1st LED part 11 is divided | segmented into several LED division part 16, and said LED division part 16 is at least said 2nd LED part 12 Can be connected to the upstream side and / or the downstream side of the third LED unit 13 or to the upstream side and / or the downstream side of the third LED unit 13. Thereby, by disperse | distributing and arrange | positioning a LED division part, the advantage which can reduce the nonuniformity of lighting and can reduce the loss in the means at the time of LED part light extinction is acquired.

  Furthermore, according to the light emitting diode driving device according to the third aspect, the plurality of LED units are connected to each other on the output line OL, and downstream of the LED dividing unit 16 connected to the output line OL. The second LED unit 12 or the third LED unit 13 is directly connected, and at the interface of the connection between the LED dividing unit 16 and the second LED unit 12 or the third LED unit 13 The output line OL is branched, and the first means or the second means can be connected to the branch line. Thereby, the LED division | segmentation part can be arrange | positioned to the upstream of an LED part, and the loss in the means at the time of LED part light extinction can be reduced.

  Furthermore, according to the light emitting diode driving device according to the fourth aspect, the second LED part 12 or the third LED part 13 is connected to the upstream side of at least one of the LED dividing parts 16, and The output line OL is branched at the interface of connection between the LED dividing unit 16 and the second LED unit 12 or the third LED unit 13, and the first means or the second means is provided on the branch line. Can be connected. Thereby, the LED division | segmentation part can be arrange | positioned in the downstream of an LED part, and the loss in the means at the time of LED part light extinction can be reduced.

  Furthermore, according to the light emitting diode driving device according to the fifth aspect, the current detection means 4 for detecting the amount of current flowing on the output line OL in which the plurality of LED portions are connected in series is provided with a plurality of sub- Current detection means is connected on the output line OL, and each sub-current detection means is between the first LED part 11 and the second LED part 12 and / or the second LED part 12 and the third LED part. The LED unit 13 can be connected in series. Thereby, the first current control means and the second current control means can easily set the threshold values for controlling the energization amounts individually.

  Furthermore, according to the light-emitting diode driving device according to the sixth aspect, the second LED unit 12 and the third LED unit 13 are configured such that the LED dividing unit 16 increases the input voltage rectified by the rectifier circuit 2. It can be turned on earlier than the second LED unit 12 and the third LED unit 13 as the input voltage decreases. Thus, by using the LED unit that is lit for the longest time as the LED dividing unit, the luminance and heat generation of the light emitting surface can be made uniform by the distributed arrangement. That is, the brightness and heat generation can be made uniform by dispersing and arranging the first LED part having the longest lighting time among the plurality of LED parts among the other LED parts. Further, since LED elements having a long lighting time and a large calorific value are not concentrated, a uniform heat distribution is achieved, which is advantageous in terms of heat dissipation.

  Furthermore, according to the light emitting diode driving device according to the seventh aspect, the fourth LED unit 14 having at least one LED element connected to the third LED unit 13 and the fourth LED unit 14 in parallel. A third means 23 for controlling the energization amount to the first LED part 11, the second LED part 12 and the third LED part 13, and a third current for controlling the third means 23. Control means 33, and the LED dividing section 16 can be disposed between the third LED section 13 and the fourth LED section 14. Thereby, the multistage circuit which light-drives the LED stage of 4 steps | paragraphs with AC power supply is realizable.

1 is a block diagram illustrating a light emitting diode driving device according to Embodiment 1. FIG. 5 is a block diagram showing a light emitting diode driving apparatus according to Embodiment 2. FIG. 1 is a circuit diagram illustrating a light emitting diode driving apparatus according to Embodiment 1. FIG. It is a graph which shows the waveform of the pulsating voltage which rectified the alternating voltage. It is a graph which shows the current waveform at the time of inputting a pulsating voltage into the circuit of FIG. It is a graph which shows the current waveform based on the control which made much use efficiency. It is a graph which shows the current waveform at the time of operation | movement of an automatic blink circuit. It is a graph which shows a mode that a peak value is reduced and illumination intensity is suppressed. It is a perspective view which shows the example which applied the light emitting diode drive device to the street lamp. It is a circuit diagram which shows the LED lighting apparatus which concerns on Example 2. FIG. 6 is a circuit diagram illustrating a light emitting diode driving apparatus according to Embodiment 3. FIG. It is a schematic diagram which shows the voltage applied at the time of OFF to the LED part which does not provide an LED division part. It is a schematic diagram which shows the voltage applied at the time of OFF to the LED part which provided the LED division part. It is a circuit diagram which shows the flow of an electric current when the automatic blink circuit act | operates in the circuit of FIG. 11, and turns off an LED assembly. FIG. 6 is a circuit diagram illustrating a light emitting diode driving apparatus according to Example 4; FIG. 10 is a circuit diagram illustrating a light-emitting diode driving apparatus according to Example 5. It is a block diagram which shows the light emitting diode drive device which this applicant developed previously.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the embodiment described below exemplifies a light emitting diode driving device for embodying the technical idea of the present invention, and the present invention does not specify the light emitting diode driving device as follows. Further, the present specification by no means specifies the members shown in the claims to the members of the embodiments. In particular, the dimensions, materials, shapes, relative arrangements, and the like of the component parts described in the embodiments are not intended to limit the scope of the present invention unless otherwise specified, and are merely explanations. It is just an example. Note that the size, positional relationship, and the like of the members shown in each drawing may be exaggerated for clarity of explanation. Furthermore, in the following description, the same name and symbol indicate the same or the same members, and detailed description thereof will be omitted as appropriate. Furthermore, each element constituting the present invention may be configured such that a plurality of elements are constituted by the same member and the plurality of elements are shared by one member, and conversely, the function of one member is constituted by a plurality of members. It can also be realized by sharing. In addition, the contents described in some examples and embodiments may be used in other examples and embodiments.

In the present specification, “connected in series” means that, unless otherwise specified, it is sufficient that they are connected in series, and as long as the series connection is maintained, another member is interposed therebetween. I do not disturb that. In the case of direct connection without interposing other members in between, it is stated in principle that it is direct connection. Further, in this specification, the term “earth” is not limited to the so-called grounding but includes a virtual grounding point. For example, a metal case of the lighting device is used as a virtual ground point.
(Embodiment 1)

  FIG. 1 shows a block diagram of a light-emitting diode driving apparatus according to Embodiment 1 of the present invention. A light-emitting diode driving device 100 shown in this figure is connected to an AC power supply AP and includes a rectifier circuit 2 for obtaining a pulsating voltage obtained by rectifying an AC voltage, and an LED assembly 10 including a plurality of LED units. Are connected in series on the output line OL. Here, three LED units are used, and the LED assembly 10 is configured by connecting the first LED unit 11, the second LED unit 12, and the third LED unit 13 in series.

Moreover, the 1st means 21 and the 2nd means 22 for controlling energizing amount are connected to the 2nd LED part 12 and the 3rd LED part 13, respectively at both ends. Since the 1st means 21 and the 2nd means 22 are provided in parallel with respect to the LED part, respectively, they constitute a bypass path for adjusting the energization amount. That is, since the amount of current bypassed by the first means 21 and the second means 22 can be adjusted, the energization amount of each LED unit can be controlled as a result. In the example of FIG. 1, the 1st means 21 is connected in parallel with the 2nd LED part 12, and 1st bypass path BP1 is formed. Moreover, the 2nd means 22 is connected in parallel with the 3rd LED part 13, and 2nd bypass path | route BP2 is formed. In this specification, since an output current may also flow through a bypass path that bypasses the LED unit or the like connected on the output line, it is included in the output line in this sense.
(Current control means)

  Further, in order to perform constant current driving, a current control means is provided for controlling the constant current circuit. In this circuit example, the first means 21, the second means 22, the first current control means 31, and the second current control means 32 constitute a kind of constant current circuit.

  The current control means is connected to the first means 21 and the second means 22 and controls operations such as ON / OFF of the first means 21 and the second means 22 and continuous variable current amount. Specifically, a first current control unit 31 that controls the operation of the first unit 21 and a second current control unit 32 that controls the operation of the second unit 22 are provided. The 1st current control means 31 and the 2nd current control means 32 monitor the electric current amount of LED, and switch the control amount of the 1st means 21 and the 2nd means 22 based on the value. The current control means are connected in series (details will be described later).

  The LED unit is a block in which one or a plurality of LED elements are connected in series and / or in parallel. As the LED element, a surface mount type (SMD) or a bullet type LED can be used as appropriate. Moreover, the package of the SMD type LED element can select the outer shape according to the application, and a rectangular type in a plan view can be used. Furthermore, it goes without saying that an LED in which a plurality of LED elements are connected in series and / or in parallel in the package can be used as the LED portion.

  The subtotal forward voltage, which is the sum of the forward voltages of the LED elements included in each LED unit, is determined by the number of LED elements connected in series. For example, when six LED elements having a forward voltage of 3.6V are used, the subtotal forward voltage is 3.6 × 6 = 21.6V.

  The light emitting diode driving device 100 switches ON / constant current control / OFF of energization of each LED unit based on the current value detected by the current detecting means. In other words, current control is based on the amount of current that is actually energized rather than the voltage value of the rectified voltage, so it is not affected by variations in the forward voltage of the LED element, and the LED unit can be accurately switched at an appropriate timing. Is realized and stable operation with high reliability is expected. For detecting the current value, a current detecting means or the like can be used.

  Specifically, in the example of FIG. 1, the first current control unit 31 controls the energization limit amount to the first LED unit 11 by the first unit 21 based on the energization amount of the first LED unit 11. Specifically, when the first means 21 and the second means 22 are in an ON state and the energization amount reaches a preset first reference current value, the first means 21 causes the first LED unit 11 to be a constant current. To drive. Thereafter, when the input voltage rises and reaches a voltage that can drive both the first LED unit 11 and the second LED unit 12, a current starts to flow through the second LED unit 12, and the current value becomes the first reference current value. If it exceeds, the 1st means 21 will be OFF. Further, the second current control unit 32 controls the energization limit amount to the first LED unit 11 and the second LED unit 12 by the second unit 22 based on the energization amount of the first LED unit 11 and the second LED unit 12. . Specifically, when the energization amount reaches a preset second reference current value, the second means 22 drives the first LED unit 11 and the second LED unit 12 at a constant current. Thereafter, when the input voltage rises and reaches a voltage that can drive the first LED unit 11, the second LED unit 12, and the third LED unit 13, a current starts to flow through the third LED unit 13. Exceeds the second reference current value, the second means 22 is turned off. Finally, the LED drive unit 3 drives the first LED unit 11, the second LED unit 12, and the third LED unit 13 with constant current.

  Here, ON / constant current control / in order from the first LED unit 11 to the second LED unit 12 and the third LED unit 13 by setting so that the first reference current value <the second reference current value. OFF can be sequentially switched.

  As described above, the LED driving device 100 uses an alternating current power supply such as a household power supply, and is arranged in series in accordance with a periodically changing pulsating voltage obtained after full-wave rectification of the alternating current. A plurality of constant current circuits configured to light up an appropriate number of elements are provided, and a plurality of LED current detection circuits can be operated so that each constant current circuit operates appropriately.

  The light emitting diode driving device 100 energizes the first LED unit 11 with a first current value, energizes the first LED unit 11 and the second LED unit 12 with a second current value larger than the first current value, and further The first LED unit 11, the second LED unit 12, and the third LED unit 13 are energized with a third current value that is larger than the second current value. In particular, by restricting the amount of power to each LED unit by constant current control, it is possible to switch the LED unit ON / constant current control / OFF according to the amount of current, and efficiently turn on the LED against the pulsating voltage Can drive.

Each LED section can be configured by connecting a plurality of light emitting diode elements in series with each other. As a result, the pulsating voltage can be effectively divided by a plurality of light emitting diode elements, and variations in the forward voltage Vf and temperature characteristics for each light emitting diode element can be absorbed to some extent, and control in units of blocks can be made uniform. However, the number of LED units and the number of light emitting diode elements constituting each LED unit can be arbitrarily set according to required brightness, input voltage, etc., for example, the LED unit can be configured with one light emitting diode element, It goes without saying that finer control can be performed by increasing the number of LEDs, or conversely, the control can be simplified by using only two LED units.
(Embodiment 2)

In the above configuration, the number of LED units is set to 3, but it goes without saying that the number of LED units can be set to 2 or 4 or more. For example, an example in which a fourth LED unit is further added to the light emitting diode driving apparatus of FIG. 1 is shown in FIG. In the light emitting diode driving device 200 shown in this figure, the fourth LED section 14, the LED driving means 3, and the current detecting means 4 are connected in series to the output line OL. The fourth LED unit 14 is also composed of a plurality of light emitting diodes, like the other LED units. In the example of FIG. 2, the fourth LED unit 14 is connected between the third LED unit 13 and the LED driving means 3. However, as long as the fourth LED unit 14 is connected in series as described above, the connection order is as follows. It can be changed appropriately. The third means 23 is connected in parallel with the fourth LED portion 14 to form a third bypass path BP3. The third means 23 is controlled by the third current control means 33. Further, a drive element control means 5 is connected to the LED drive means 3. Thus, by further increasing the number of connections of the LED units, it is possible to perform finer switching control between the LED units and further improve the LED utilization efficiency. In addition, the number of LED units can be increased to 5 or more, thereby enabling more detailed lighting switching control. Further, in the example of FIG. 2, the switching operation in which each LED unit is turned ON / OFF is divided almost equally with respect to the input current as shown in FIG. 5 described later. The LED units may be switched with different currents (details will be described later). The energization amount of the LED drive means 3 connected on the output line is controlled by the drive element control means 5. Note that when the application voltage of the LED unit is designed to match the maximum value of the input voltage, or when the value of the input voltage itself is equal to the application voltage of the LED unit, the LED driving means 3 and the drive element control means 5 are not provided. Also good.
(Automatic flashing circuit 50)

  Furthermore, an automatic flashing circuit 50 can be provided between the LED assembly 10 and the rectifier circuit 2. The automatic flashing circuit 50 includes an illuminance detection unit 51 that detects the illuminance of the surrounding environment, an input voltage detection unit 52 that detects the voltage value of the input voltage that has been full-wave rectified by the rectifier circuit 2, and an input control that limits the amount of current flow. Means 53. The input control unit 53 defines the current limit amount based on the output signal of the illuminance detection unit 51 and the output signal of the input voltage detection unit 52. Here, the current limit amount is determined by the product of the illuminance and the input voltage. With this configuration, not only the conventional ON / OFF control based on the illuminance but also the control of the energization amount based on the voltage value of the input voltage for full-wave rectification can be realized. As a result, there is an advantage that the load on the LED driving means 3 can be reduced.

  In particular, since the LED driving device 100 has a bypass path in the LED unit as a multi-stage circuit, there is a problem that an excessive load is applied to the LED driving means connected in series to the output line OL, resulting in a loss. That is, when the current value of the output line OL decreases, the bypass path automatically operates and the current does not flow to the LED unit, so that the input voltage applied to the output line OL is applied to the LED driving means. For this reason, the LED driving means is required to have a high withstand voltage, and the loss becomes large, and a heat dissipation measure against heat generation is also required. In the case of a normal LED drive circuit that is not a multi-stage circuit, even if the current is reduced, the LED elements are connected in series, so that the voltage does not become 0V. On the other hand, in the multistage circuit according to the present embodiment, since each LED unit has a bypass path as described above, there is a problem peculiar to the multistage circuit that the voltage is bypassed and becomes 0 V when the current decreases. By using the automatic flashing circuit 50 for this problem, there is an advantage that the LED driving means 3 of the output line OL can be turned off to reduce the loss.

  Further, in this method, since the DC voltage is not generated by stepping down the pulsating voltage as in the prior art, a capacitor for smoothing becomes unnecessary, and the reliability and long life of the device are achieved. The capacitance of a capacitor used in a general constant current circuit or a circuit having only a resistor needs to be about 100 to 300 μF. Such a large capacity can be realized only with an electrolytic capacitor at present, and becomes a large-sized capacitor. When a large-size capacitor is mounted on the same substrate as the LED element, the capacitor may inhibit light distribution from the LED element, and the compact design is significantly hindered. In addition, the electrolytic capacitor has a certain life, and this life is remarkably small with respect to the life of the LED element. Therefore, the electrolytic capacitor determines the product life, and the advantage inherent to the LED element of long life cannot be utilized. For example, the life of an aluminum electrolytic capacitor having a large capacity is generally about 20,000 hours. On the other hand, when an LED is used as a light source for illumination, the lifetime of the LED element is about 40,000 hours. Therefore, in a circuit using an electrolytic capacitor, the lifetime of the capacitor affects the product lifetime. .

  In contrast, the multistage circuit described above does not use a smoothing capacitor. Even if it is used temporarily, the capacitance of about 10 μF is sufficient, so that it can be constituted by a part having an extremely long life such as a film capacitor. The reason why the capacitance can be reduced in this way is that it is configured based on the idea that a part of the LED element group connected in series is lit when the input voltage is inherently low in a multistage circuit. In other words, the LED element can be driven even with a certain low voltage, and therefore it is sufficient that the voltage to be maintained by the capacitor is low.

As described above, the LED driving device 100 can optimize the crest factor without determining the product life of the LED lighting device driven by alternating current with the capacitor.
Example 1

  Next, a specific circuit configuration example in which the configuration of FIG. 2 is realized by using a semiconductor element is shown in FIG. In the light emitting diode driving device 500, an output line OL for connecting LED units in series and a control line CL for connecting current control units in series are connected substantially in parallel. Thus, by connecting a plurality of LED units and current control means in parallel, the circuit configuration can be simplified, the wiring pattern can be further simplified, and the necessary number of conductors and pattern length can be reduced. The width of the circuit board to be mounted can be reduced, which contributes to miniaturization of the circuit.

The light emitting diode driving device 300 uses a diode bridge as the rectifier circuit 2 connected to the AC power supply AP. In addition, a fuse and surge protection circuit for preventing overcurrent are provided between the AC power supply AP and the rectifier circuit 2.
(AC power supply AP)

As the AC power supply AP, a commercial power supply of 100V or 200V can be suitably used. 100V or 200V of this commercial power supply is an effective value, and the maximum voltage of the rectified waveform obtained by full-wave rectification is about 141V or 282V.
(LED part)

  Each LED unit is connected in series with each other, divided into a plurality of blocks, and is connected to the first means 21, the second means 22, and the third means 23 by pulling out terminals from the boundaries between the blocks. In the example of FIG. 3, the LED assembly 10 is configured by four groups of a first LED unit 11, a second LED unit 12, a third LED unit 13, and a fourth LED unit 14.

Each LED part 11-14 shown in FIG. 3 represents the LED package 1 in which one LED symbol mounts a plurality of LED chips. In this example, each LED package 1 has six LED chips mounted thereon. Since each LED unit 11 uses three LED packages, a total of 3 × 4 = 12 LED packages and a total of 72 LED chips are used as the LED assembly 10. The number of light emitting diodes connected to each LED unit or the number of LED units connected is determined by the added value of forward voltages, that is, the total number of LED elements connected in series and the power supply voltage to be used. For example, when commercial power is used, the total forward voltage Vf _all is the sum of the Vf of each LED unit is set to be about 282V, or less.

  The LED unit and the LED dividing unit 16 described later include one or more arbitrary numbers of LED elements. As the LED element, one LED chip or a plurality of LED chips combined in one package can be used. In this example, an LED package 1 including six LED chips is used as one LED element shown in the figure.

In the example of FIG. 3, the four LED portions are designed to have the same Vf. However, the present invention is not limited to this example, and as described above, the number of LED units may be 3 or less, or 5 or more. By increasing the number of LED units, it is possible to increase the number of constant current controls and perform finer switching control between the LED units. Furthermore, the Vf of each LED part does not need to be the same.
(First to third means)

  The first means, the second means, and the third means are members for constant current driving corresponding to each LED unit. Such first to third means are constituted by switching elements such as transistors. In particular, FETs are preferable because the saturation voltage between the source and the drain is almost zero, and the amount of current supplied to the LED portion is not hindered. However, it goes without saying that the first means to the third means are not limited to FETs, and can be constituted by bipolar transistors or the like.

  In the example of FIG. 3, LED current control transistors are used as the first to third means. Specifically, the second LED unit 12, the third LED unit 13, the fourth LED unit 14, and the current limiting unit 3 include a first LED current control transistor 21B and a second LED, which are first to third units, respectively. The current control transistor 22B and the third LED current control transistor 23B are connected. Each LED current control transistor is switched between ON state and constant current control in accordance with the current amount of the LED section in the previous stage. When the LED current control transistor is turned off, no current flows through the bypass path, and the LED portion is energized. That is, since the amount of current bypassed by each of the first to third means can be adjusted, the energization amount of each LED unit can be controlled as a result. In the example of FIG. 3, the first means 21 is connected in parallel with the second LED unit 12 to form the first bypass path BP1. Moreover, the 2nd means 22 is connected in parallel with the 3rd LED part 13, and 2nd bypass path | route BP2 is formed. Further, the third means 23 is connected in parallel with the fourth LED portion 14 to form a third bypass path BP3. Furthermore, the fourth LED current control transistor 24B is connected to control the energization amount to the first LED unit 11, the second LED unit 12, the third LED unit 13 and the fourth LED unit 14.

  Here, the first LED unit 11 is not provided with a bypass path or first to third means connected in parallel. This is because the first means 11 connected in parallel with the second LED unit 12 controls the amount of current of the first LED unit 11. For the fourth LED unit 14, the fourth current detection transistor 34B performs current control.

  In the example of FIG. 3, the fourth LED current control transistor 24 </ b> B is the LED driving unit 3. In addition to the configuration in which the LED driving unit is used alone as described above, for example, by connecting a resistor in parallel to the LED driving unit, the current is bypassed when the amount of current increases, and the LED driving unit is connected to the LED driving unit. You may comprise so that load may be reduced.

In the example of FIG. 3, an FET is used as the LED current control transistor. In the configuration in which ON / OFF switching is controlled in units of LED units using the first LED current control transistor 21B, the second LED current control transistor 22B, and the third LED current control transistor 23B, LED current control at each stage is performed. Since control semiconductor elements such as FETs constituting the transistors are respectively connected to both ends of the LED portion, the withstand voltage of the control semiconductor element is protected by the subtotal forward voltage of the LED portion. For this reason, there is an advantage that a small semiconductor element having a low withstand voltage can be used.
(First current control means 31, second current control means 32, third current control means 33)

  The 1st current control means 31, the 2nd current control means 32, and the 3rd current control means 33 are members which control so that the 1st-3rd means corresponding to a LED part may perform constant current drive at an appropriate timing. . The first to third current control means can also use switching elements such as transistors. In particular, the bipolar transistor can be suitably used for detecting the amount of current. In this example, the first current control means 31 is the first current detection transistor 31B, the second current control means 32 is the second current detection transistor 32B, the third current control means 33 is the third current detection transistor 33B, and the drive element control means Reference numerals 5 and 4 denote fourth current detection transistors 34B, respectively. Needless to say, the current control means is not limited to the bipolar transistor, and can be constituted by a comparator, an operational amplifier or the like.

In the example of FIG. 3, the current control means is constituted by a current detection transistor. Each current detection transistor controls the operation of the LED current control transistor. That is, each current detection transistor is turned ON / constant current control / OFF, thereby switching the LED current control transistor to OFF / constant current control / ON.
(Current detection means 4)

  On the other hand, the current detection means 4 includes a plurality of sub current detection means. In the example of FIG. 3, the four LED current detection resistors include a first LED current detection resistor 4A, a second LED current detection resistor 4B, a third LED current detection resistor 4C, and a fourth LED current detection resistor 4D. These also function as protective resistors for the LEDs. The LED current detection resistors 4A, 4B, 4C, and 4D detect constant current drive of the LED elements constituting the LED unit by detecting the current supplied to the LED assembly 10 in which the LED units are connected in series by a voltage drop or the like. Do. Further, in order to perform constant current driving, a current control means is provided for controlling the constant current circuit. In this circuit example, the first means 21, the second means 22, the third means 23, the first current control means 31, the second current control means 32, and the third current control means 33 constitute a kind of constant current circuit. .

The resistance value of each LED current detection resistor defines at which current timing each current detection transistor is turned on / off. Here, the resistance values of the LED current detection resistors are set so that the first current detection transistor 31B, the second current detection transistor 32B, the third current detection transistor 33B, and the fourth current detection transistor 34B are turned on in this order. Yes.
(Reference current value)

Here, the first current detection transistor 31B switches the first LED current control transistor 21B from ON to OFF, and the second current detection transistor 32B switches the second LED current control transistor 22B from ON to OFF. Set lower than the second reference current value. The third current detection transistor 33B sets a third reference current value for switching the third LED current control transistor 23B from ON to OFF higher than the second reference current value. Further, the fourth current detection transistor 34B sets a fourth reference current value for switching the fourth LED current control transistor 24B from ON to OFF higher than the third reference current value. By setting the first reference current value <the second reference current value <the third reference current value <the fourth reference current value, the first reference current value <the second reference current value <the fourth reference current value. ON / constant current control / OFF can be sequentially switched in the order from the LED unit 11 to the second LED unit 12, the third LED unit 13, and the fourth LED unit 14. When the input voltage decreases, the LEDs are turned off in the reverse order.
(Description of operation)

The light emitting diode driving device 300 can improve the LED utilization efficiency and power factor while maintaining a power supply efficiency of 80% or more, and can be composed of a circuit mainly composed of semiconductor elements. Can be realized. The operation of the first to third current control means and the first to third means in the case of inputting the pulsating voltage of FIG. 4 in the circuit example of FIG. 3 will be described below with reference to the current waveform of FIG. . The input voltage applied to the LED assembly 10 is the pulsating voltage of FIG. Here, the operation for one cycle is examined. First, while the voltage rises from 0 V to the subtotal forward voltage Vf _B1 of the first LED unit 11, the current is blocked by the first LED unit 11. Therefore, as shown in FIG. 5, there is a section where no current flows. When twelve LED elements having the forward voltage of 3.6 V described above are used, the subtotal forward voltage Vf _B1 is 3.6 × 12 = 43.2 V, so that the pulsating voltage is between 0V and 43.2V. Do not energize.

Next, when the pulsating voltage rises to near the subtotal forward voltage Vf _B1 of the first LED unit 11, the first LED current control transistor 21B, the second LED current control transistor 22B, and the third LED current control in the circuit diagram of FIG. Since all the transistors 23B are ON, the first bypass path BP1, the second bypass path BP2, and the third bypass path BP3 are all opened. As a result, current begins to flow through the path of the first LED unit 11 → the first LED current control transistor 21B → the second LED current control transistor 22B → the third LED current control transistor 23B → the fourth LED current control transistor 24B. As the pulsating voltage increases, the current flowing through the first LED unit 11 also increases, so that the amount of current gradually increases as shown in FIG. As the amount of current further increases, the amount of current flowing from the first LED section 11 to the first LED current detection resistor 4B through the first bypass path BP1, the second bypass path BP2, and the third bypass path BP3 also increases.

When the pulsating voltage further rises and reaches the current set by the first LED current detection resistor 4A, the first current detection transistor 31B is turned on to start energization. As the pulsating voltage rises, the collector current of the first current detection transistor 31B is gradually increased. As a result, the voltage drop of the first transistor load resistor 36B is increased, and the collector voltage of the first current detection transistor 31B is lowered. For this reason, the gate voltage of the first LED current control transistor 21B decreases and switches from ON to OFF. As a result, the first bypass path BP1 is interrupted and energization of the second LED unit 12 is started. At this time, during the transition period in which the first current control transistor 21B is switched from ON to OFF, that is, until the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 of the first LED unit 11 and the second LED unit 12, The second LED unit 12 is not lit, and the first LED unit 11 is driven with a constant current. As a result, the level is I-1 in FIG.

In this state, when the pulsating voltage continues to rise and reaches the subtotal forward voltage Vf _B1 + Vf _B2 of the first LED unit 11 and the second LED unit 12, the second LED unit 12 starts to be turned on, as shown in FIG. Thus, the increase in current value is resumed. Then, when the current gradually increases and the amount of current flowing through the second LED current detection resistor 4B increases, when the current value set by the second LED current detection resistor 4B is reached, the second current detection transistor 32B operates. Start. As a result, the collector current of the second current detection transistor 32B is gradually increased, so that the voltage drop of the second transistor load resistor 37B increases. As a result, the gate voltage of the second LED current control transistor 22B decreases, switching from ON to OFF, the second bypass path BP2 is interrupted, and energization to the third LED unit 13 is started. At this time, until the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 + Vf _B3 of the first LED unit 11 to the third LED unit 13, the third LED unit 13 is not lit, and the first LED unit 11 and the second LED unit 12 are driven with a constant current. As a result, the level is I-2 in FIG.

Similarly, ON / OFF switching and constant current driving are performed for the third LED unit 13. That is, when the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 + Vf _B3 of the first LED unit 11 to the third LED unit 13, the lighting of the third LED unit 13 is started, as shown in FIG. The increase in current value is resumed. When the amount of current flowing through the third LED current detection resistor 4C increases and reaches the current value set by the third LED current detection resistor 4C, the third current detection transistor 33B starts operating. Then, the collector current of the third current detection transistor 33B is gradually increased, and the voltage drop of the third transistor load resistor 38 is increased. As a result, the gate voltage of the third LED current control transistor 23B decreases, switching from ON to OFF, the third bypass path BP3 is interrupted, and energization to the fourth LED unit 14 is started. At this time, the fourth LED unit 14 is not lit until the pulsating voltage reaches the voltage Vf _B1 + Vf _B2 + Vf _B3 + Vf _3A of the first LED unit 11 to the fourth LED unit 14, and the first LED unit 11 is not lit. The second LED unit 12 and the third LED unit 13 are driven with a constant current. As a result, the level I-3 in FIG. 5 is realized.

Further, ON / OFF switching and constant current driving are also performed for the fourth LED unit 14. That is, when the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 + Vf _B3 + Vf _B4 of the first LED unit 11 to the fourth LED unit 14, the fourth LED unit 14 is turned on, as shown in FIG. Thus, the increase in current value is resumed. When the amount of current flowing through the fourth LED current detection resistor 4D increases and reaches the current value set by the fourth LED current detection resistor 4D, the fourth current detection transistor 34B starts operating. Then, the collector current of the fourth current detection transistor 34B is gradually increased, and the voltage drop of the fourth transistor load resistor 39B is increased. As a result, the gate voltage of the fourth LED current control transistor 24B decreases, and the current supply to the LED current control transistor 24B concentrates. At this time, until the pulsating voltage reaches the voltage Vf _B1 + Vf _B2 + Vf _B3 + Vf _3A of the first LED unit 11 to the LED current control transistor 24B, the first LED unit 11, the second LED unit 12, and the third LED The unit 13 and the fourth LED unit 14 are driven with a constant current. As a result, the level I-4 in FIG. 5 is realized.

  In the vicinity of the maximum pulsating voltage, all the LED current control transistors 21B, 22B, and 23B are completely turned off, and a current flows through all the LED assemblies 10 through the LED current detection resistors. Thereby, the electric power near the maximum voltage can be used effectively. However, it is not always necessary to turn off the fourth means in the final stage. For example, even if the fourth LED current control transistor 24B is kept on, it is possible to supply current to all the LEDs. In this case, the current value can be limited by applying constant current control at the peak portion of the input voltage by not turning off the fourth LED current control transistor 24B.

  When the pulsating voltage reaches the maximum voltage of 141 V, the voltage value starts to decrease, indicating an operation pattern opposite to the above. Further, after the pulsating current voltage reaches 0 V which is the minimum voltage, the above operation is repeated because it starts to rise again.

  Thus, the level for constant current drive can be freely set by setting the LED current detection resistor and the current detection transistor. In the above circuit example, a high-performance LED driving device such as small size, low cost, and light weight can be realized by not using a coil or a large-capacity capacitor. Furthermore, suppression of harmonic noise can be expected by not performing high-frequency switching.

  Further, in the above method, since control is performed according to the amount of current that actually flows through the LED unit or the like, accurate lighting control can be performed without depending on variations in characteristics of each LED element, in particular, individual differences in Vf. Further, since the control itself can be realized with a very simple circuit configuration, an expensive control element such as a microcomputer is unnecessary, and it can be configured only with a semiconductor element, and there is an advantage that the cost can be reduced.

In addition, in the above configuration, the energization amount of the LED unit is not constant, and the current value is changed by different constant current control. As a result, the life of the LED unit having a long lighting time can be reduced by suppressing the amount of current. Specifically, the constant current control amount, that is, the energization control amount of the first LED unit that has the longest lighting time is minimized, and the energization control amount of the fourth LED unit that has the shortest lighting time is maximized. As a result, since the current value when the first LED unit is turned on when the fourth LED unit is turned off is small, the heat generation amount (current value × lighting time) can also be suppressed. That is, it is possible to suppress deterioration of the first LED portion when compared with the fourth LED portion. The same can be said for the relationship with the second LED unit. In this way, the constant current control current amount is not constant, but by changing the LED portion having a longer lighting time to be lower, the non-uniformity of the life characteristics of the light-emitting diode element is alleviated and stable for a longer period of time. Thus, lighting control of the usable light emitting diode is realized.
(LED current detection resistor)

  In the above example, the LED current detection resistors are individually provided for each LED unit and the like. Specifically, as shown in FIG. 3, the current detection of the first LED unit 11 is performed by the first LED current detection resistor 4A, the current detection of the second LED unit 12 is performed by the second LED current detection resistor 4B, and the third Current detection of the LED unit 13 is performed by the third LED current detection resistor 4C, and current detection of the fourth LED unit 14 is performed by the fourth LED current detection resistor 4D. However, the LED current detection resistors constituting the current detection means may be shared by the LED units and the like. That is, each current control unit performs control based on the current amount of the common current detection unit, whereby the circuit configuration can be simplified.

In the above circuit example, because the LED assembly 10 is connected in series with a single line, the current waveform is shown in the graph of FIG. 5 by performing constant current control with a different current value for each LED unit. As shown in step, it is stepped. On the other hand, an example of control in which utilization efficiency is more important than power factor is shown in the voltage waveform of FIG. In this control example, the resistance value is set so that the constant current control of each LED unit is closer to each other than in the example of FIG. 5, and the output is increased by increasing the total current amount and bright illumination. Light can be obtained. The measured values when the circuit constant is configured as the LED current waveform shown in FIG. 6 are: power supply efficiency = 90%, LED utilization efficiency = 53%, power factor 95%, and the power factor is slightly reduced compared to FIG. However, it was confirmed that the LED utilization efficiency could be improved. In this way, even if the circuit configuration is the same, it is possible to configure a lighting device corresponding to the required specifications by selecting circuit constants.
(Reference current value)

  Here, the first current detection transistor 31B switches the first LED current control transistor 21B from ON to OFF, and the second current detection transistor 32B switches the second LED current control transistor 22B from ON to OFF. Set lower than the second reference current value. The third current detection transistor 33B sets a third reference current value for switching the third LED current control transistor 23B from ON to OFF higher than the second reference current value. Further, the fourth current detection transistor 34B sets a fourth reference current value for switching the fourth LED current control transistor 24B from ON to OFF higher than the third reference current value. In this way, by setting the first reference current value <second reference current value <third reference current value <fourth reference current value, the first LED unit 11, the second LED unit 12, the third LED as described above. The unit 13 is switched from OFF to ON in the order of the LED driving means 3 (fourth LED current control transistor 24B), and in the reverse order from ON to OFF.

An example of controlling the current waveform of FIG. 5 using the circuit of FIG. 3 will be described. The AC voltage of the commercial power supply is rectified by the rectifier circuit 2 and becomes the pulsating voltage of FIG. In the circuit example of FIG. 3, no bypass capacitor is used. While the voltage rises from 0 V to the subtotal forward voltage Vf _B1 of the first LED unit 11, the current is blocked by the first LED unit 11, and no current flows. When the pulsating voltage rises to near the subtotal forward voltage Vf _B1 , the first LED current control transistor 21B, the second LED current control transistor 22B, the third LED current control transistor 23B, and the fourth LED current control in the circuit diagram of FIG. Since all the transistors 24B are ON, the first bypass path BP1, the second bypass path BP2, the third bypass path BP3, and the fourth bypass path BP4 are all opened, and the current is from the first LED unit 11 to the first LED. Current control transistor 21B → first LED current detection resistor 4B → second LED current control transistor 22B → second LED current detection resistor 4B → third LED current control transistor 23B → third LED current detection resistor 4C → fourth LED current control It starts to flow along the path of the transistor 24B → the fourth LED current detection resistor 4D. As the pulsating voltage increases, the current flowing through the first LED unit 11 increases, and the amount of current flowing through the first LED current detection resistor 4B also increases.

When the pulsating voltage further rises and reaches the current set by the first LED current detection resistor 4A, the first current detection transistor 31B is turned on to start energization. As the pulsating voltage increases, the collector current of the first current detection transistor 31B is gradually increased. As a result, the gate voltage applied from the first transistor load resistor 36B to the first current control transistor 21B decreases. Then, a constant current operation is performed for a while, and when the input voltage reaches a predetermined voltage at which the first LED unit 11 and the second LED unit 12 can be turned on simultaneously, an overflow occurs and switches from ON to OFF. As a result, the first bypass path BP1 is interrupted and energization of the second LED unit 12 is started. At this time, until the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 of the first LED unit 11 and the second LED unit 12, the second LED unit 12 is not lit and the first LED unit 11 is Constant current drive.

In this state, when the pulsating current voltage rises and reaches the subtotal forward voltage Vf _B1 + Vf _B2 of the first LED unit 11 and the second LED unit 12, the lighting of the second LED unit 12 is started. As a result of the gradual increase in the amount of current supplied to the second LED current detection resistor 4B, when the set current value is reached, the second current detection transistor 32B starts operating. As a result of the gradual increase in the collector current of the second current detection transistor 32B, the current branched to the second LED current control transistor 22B side decreases, and the gate voltage of the second LED current control transistor 22B decreases. Then, it is switched from ON to OFF through constant current drive, the second bypass path BP2 is cut off, and energization to the third LED unit 13 is started. At this time, until the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 + Vf _B3 of the first LED unit 11 to the third LED unit 13, the third LED unit 13 is not lit and the second LED unit 12 is driven by constant current.

Similarly, when the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 + Vf _B3 of the first LED unit 11 to the third LED unit 13, the lighting of the third LED unit 13 is started, and the increase of the current value is resumed. The When the amount of current flowing through the third LED current detection resistor 4C increases and reaches the set current value, the third current detection transistor 33B starts operating. Then, the collector current of the third current detection transistor 33B is gradually increased, and the current flowing from the third transistor load resistor 38B to the third LED current control transistor 23B is branched to the third current detection transistor 33B side. The gate voltage of the LED current control transistor 23 decreases, switches from ON to OFF through constant current driving, the third bypass path 3 is cut off, and energization to the fourth LED unit 14 is started. At this time, the fourth LED unit 14 is not lit until the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 + Vf _B3 + Vf _B4 of the first LED unit 11 to the fourth LED unit 14, and the third LED unit 14 is not lit. The LED unit 13 is driven with a constant current.

When the pulsating voltage reaches the subtotal forward voltage Vf _B1 + Vf _B2 + Vf _B3 + Vf _B4 of the first LED unit 11 to the fourth LED unit 14, the lighting of the fourth LED unit 14 is started and the increase in the current value is resumed. Is done. When the amount of current flowing through the fourth LED current detection resistor 4D increases and reaches the set current value, the fourth current detection transistor 34B starts operating. Then, the collector current of the fourth current detection transistor 34B is gradually increased, and the current flowing from the fourth transistor load resistor 39B to the fourth LED current control transistor 24B is branched to the fourth current detection transistor 34B side. The gate voltage of the LED current control transistor 24B decreases, and energization to the LED current control transistor 24B is continued while the fourth bypass path BP4 is in the ON state.

  In the vicinity of the maximum pulsating voltage, all the LED current control transistors 21B, 22B, and 23B are completely turned off, and a current flows to all LEDs through the fourth LED current detection resistor 4D. Thereby, the electric power near the maximum voltage can be used effectively. When the pulsating voltage reaches the maximum voltage of 141 V, the voltage value starts to decrease, and the operation opposite to the above occurs.

  In this circuit example, the current values for operating the LED units and the LED driving means 3 can be easily adjusted individually by the LED current detection resistors. On the other hand, by using a plurality of LED current detection resistors, heat loss due to these increases, and there is a demerit that the LED part is divided as a module.

  On the other hand, as a merit, there is no crossing of wiring, and a three-dimensional wiring is unnecessary and a circuit configuration is easy. In the above circuit, the first means 21, the first current control means 31, and the first current detection means 4A turn on / off the first bypass path BP1 based on the energization amount of the first LED unit 11. The first switching means for switching is configured, and the second means 22, the second current control means 32, and the second current detection means 4B are based on the energization amounts of the first LED portion 11 and the second LED portion 12. Second switching means for switching ON / OFF of the second bypass route BP2 is configured.

In the above examples, the first LED unit 11 is switched to the second LED unit 12, the third LED unit 13, and the fourth LED unit 14 in this order, and the fourth LED unit 14 to the third LED unit 13, The second LED unit 12 and the first LED unit 11 are switched off in this order. For this reason, the lighting time of each LED part differs. Therefore, it is preferable to arrange the LED elements so that the fourth LED part having a long turn-off period is not conspicuous and not dispersed for each LED part. For example, for each row, the LED element belonging to the first LED part, the LED element belonging to the second LED part, the LED element belonging to the third LED part, the LED element belonging to the fourth LED part, and the first, second, third , Fourth, and LED elements are alternately arranged. Alternatively, from the upper left to the right, not in row units, but from the upper left to the right, LED elements belonging to the first LED part, LED elements belonging to the second LED part, LED elements belonging to the third LED part, LED elements belonging to the fourth LED part, The LED elements belonging to different LED sections are arranged one by one in the order of the first, second, third, fourth, and lower right. Also, the lighting time is not limited to one by one, but by arranging LED elements by appropriately dispersing LED units, such as a unit of two, three or more units, or a configuration in which the units are arranged apart from each other in a periodic arrangement. The difference can be made inconspicuous. Thereby, even if it repeats lighting with a 60 Hz cycle of a commercial power supply, it can be used as if the LED elements are continuously lit without making the user aware of blinking. The same effect can be obtained by using a separate inverter circuit and increasing the lighting cycle.
(Details of automatic flashing circuit 50)

3 is provided with an automatic blinking circuit 50 between the rectifier circuit 2 and the LED driving apparatus 300 of FIG. 3 includes a phototransistor as the illuminance detection means 51, an illuminance detection base resistor as the input voltage detection means 52, and an input current control transistor 53A as the input control means 53. This automatic flashing circuit 50 is connected to an input control means 53 on the control line CL for controlling the drive element control means 5 (fourth current detection transistor 34A) and upstream of the drive element control means 5. Yes. As a result, the input control means 53 is turned on, the control line CL is branched and a current flows, so that the drive element control means 5 can be controlled to operate the LED drive means 3, and the LED section connected to the output line OL. Automatic flashing is achieved by adjusting the current of the. Specifically, when the automatic blinking circuit 50 is operated to turn off the LED assembly 10, the current is branched so that the fourth current detection transistor 34 </ b> B that is the LED driving unit 3 is not energized. .
(Illuminance detection means 51)

As the illuminance detection means 51, an illuminance sensor capable of detecting an illuminance change in the surrounding environment can be used. Examples of such illuminance sensors include phototransistors, photo ICs, photodiodes, CdS, and the like. These elements generally detect the illuminance as an electrical change by changing the current value according to the illuminance. Among these, a phototransistor is preferable because it has a higher response speed than a photo IC. In particular, in a multi-stage circuit, since a response speed on the order of μs is required, a phototransistor is more suitable than a photo IC of about ms. The phototransistor has the collector side connected to the + side of the rectifier circuit 2 via the illuminance detection collector resistor 55. The emitter side is grounded via an illuminance detecting emitter resistor 56 and a high frequency component removing capacitor 57.
(Input voltage detection means 52)

The input voltage detection means 52 is an element that emits an output signal corresponding to the input voltage, and a resistor can be suitably used. The illuminance detection base resistor which is the input voltage detection means 52 shown in FIG. 3 has one end connected to the collector side of the phototransistor and the other end grounded via an input voltage detection base resistor 58 described later.
(Input control means 53)

  Based on the output signal of the illuminance detection means 51 and the output signal of the input voltage detection means 52, the input control means 53 branches the current flowing through the control line CL of the light emitting diode driving device 300 through the current limit line LL, and outputs the output line. Suppress lighting of the LED assembly on the OL. Here, a bipolar transistor is used with the input control means 53 as the input current control transistor 53A. The input current control transistor 53A has its emitter side grounded and its collector side connected to the current limit line LL. The current limit line LL branches the control line CL. The base side is grounded via the input voltage detection base resistor 58. Further, the emitter side of the phototransistor is connected to the base side via an illuminance detection emitter resistor 56, and this is connected in parallel to an input voltage detection resistor 52A as the input voltage detection means 52. The input current control transistor 53A is inputted by adding together the voltage drop generated by the output current of the phototransistor and the output current flowing through the input voltage detection resistor 52A.

  When the LED driving unit 3 is controlled only according to the illuminance, the current control transistors 21B to 23B are bypassed in the intermediate state from the lighting state to the extinguishing state or from the extinguishing state to the lighting state. As a result, a current flows in a state where a large voltage is applied to the LED 3, and there is a problem that the loss of the LED driving means 3 increases. Therefore, by adding a periodically changing pulsating voltage (input voltage) to the control by the input voltage detecting means 52, the ON / OFF threshold value of the LED driving means 3 becomes clear (the intermediate state is lost). ), Loss of the LED driving means 3 can be prevented. Conventionally, there is no idea of using an automatic blinking circuit for such an application, and the present technology can relax the specifications such as the rating of the LED driving means, which can contribute to a reduction in circuit configuration cost. Further, in this configuration, since the rectified pulsating voltage is not required to be smoothed, an electric field capacitor for smoothing can be dispensed with, which can contribute to the reliability and long life of the LED lighting device.

  In the example of FIG. 3, the current limit amount is determined by the product of the illuminance and the input voltage. Thus, not only the illuminance of the surrounding environment is detected and turned on / off, but also the energization amount can be controlled based on the voltage value of the input voltage subjected to full-wave rectification, and the load on the LED driving means 3 can be reduced. Needless to say, the automatic flashing circuit can be externally mounted in addition to being incorporated in the lighting device.

  FIG. 7 shows a current waveform when the automatic flashing circuit is operated. In this example, the current limit amount by the input control means 53 is increased as the illuminance increases, and the current limit amount is decreased as the illuminance decreases. For example, when a light-emitting diode driving device is used for a street lamp, if the lighting is relatively bright at dusk, lighting of the street lamp is unnecessary or only a little lighting is required, so the current limit amount is increased, in other words, the energization amount is decreased. . In this circuit example, as the amount of current increases, the first LED unit 11, the second LED unit, the third LED unit 13, and the fourth LED unit 14 are turned on in this order. 14, the 3rd LED part 13, the 2nd LED part 12, and the 1st LED part 11 are light-extinguished in order. As a result, as shown in FIG. 7, the current waveform changes so as to start missing from the central part of the chevron, and as the current limit increases, that is, as the illuminance increases, the missing part spreads left and right. In the example of FIG. 7, the dashed line indicates the current waveform at 100 lux, the broken line indicates 150 lux, and the solid line indicates 250 lux.

  As described above, with the configuration in which the current is limited so that the missing portion spreads from the central portion to the left and right as the illuminance rises, an advantage that flickering of lighting at high illuminance can be reduced can be obtained. That is, as shown in FIG. 8, generally, the peak value is generally reduced, and in other words, the amount of current is limited from the left and right of the waveform. In this method, the higher the illuminance, the shorter the lighting time of the LED, which may be recognized by the user as flicker. On the other hand, if the current is limited so that it is missing from the middle of the current waveform, the left and right current waveforms remain, in other words, the lighting time is relatively long, so that the flicker can be reduced compared to the method of narrowing the current waveform from the left and right An effect is obtained.

  In the above configuration, the usage time for each LED element is different for each LED unit. Specifically, the lighting time of the first LED unit 11 is the longest, and the lighting time of the fourth LED unit 14 is the shortest. For this reason, suppression of variation in element lifetime due to use frequency can also be considered. In the above circuit configuration, since the LED units are connected in series, it is difficult to control the voltage of each LED unit. For this reason, about the LED part with high use frequency, the number of LED elements to be connected is increased, and by connecting not only in series but also in parallel, the current amount per element can be reduced and heat loss can be suppressed.

In the light emitting diode driving device 100 of the first embodiment, the wiring pattern is simplified by configuring the output line OL and the signal line CL in a ladder shape so that the circuit wiring patterns do not intersect. Specifically, for the output line OL, a first LED current control transistor 21B, a second LED current control transistor 22B, a third LED current control transistor 23B, and a fourth LED current control transistor 24B are connected in series. On the other hand, the first current detection transistor 31B constituting the first current control means 31, the second current detection transistor 32B constituting the second current control means 32, the third current detection transistor 33B constituting the third current control means 33, A fourth current detection transistor 34B constituting the drive element control means 5 is connected in series. Thus, by connecting the current control means in series, it is possible to avoid the intersection of the wirings between them and simplify the wiring pattern. Further, by simplifying the wiring pattern, the width of the wiring can be widened, and the electrical resistance of the wiring pattern can be reduced. Furthermore, it leads to the improvement of heat dissipation.

  The LED driving device 100 shown in FIG. 3 includes a control line CL in which a plurality of LED units are connected in series, and current control means for turning these LED units on and off at appropriate timing and performing constant current control. The control line CL connected in series is substantially parallel. Further, a longitudinal line CR that bridges the output line OL and the control line CL is connected in a ladder shape.

  In this way, the circuit wiring patterns can be simplified so as not to intersect. As a result, it is possible to obtain an advantage that the line width of the conducting wire can be widened, the resistance value is reduced, and heat dissipation using the wiring pattern is promoted. Furthermore, since the circuit length can be shortened, the circuit pattern is simplified, which is advantageous in terms of heat dissipation. In particular, when the LED driving device 500 is used for a street lamp as shown in FIG. 9, the shape of the street lamp is often elongated, and the circuit board is often elongated according to the shape. Even in such a shape, it is advantageous that the circuit pattern can be widened by designing the circuit length to be short.

In addition, since the shape of the substrate can be elongated by configuring the LED portions in a row, an illumination device suitable for a street light having an elongated shape as shown in FIG. 9 can be realized. The example of FIG. 9 includes a case portion 75 that houses the light-emitting diode driving device, a fixing portion 76 that attaches the case portion 75 to a pole or the like, and a sensor portion 77 that incorporates an automatic flasher. Thus, in a street lamp in which the outer shape of the case portion is elongated, a substrate in which the LED portions are arranged in a straight line in a row can be suitably used.
(Example 2)

Furthermore, by utilizing the long lighting time of the first LED unit 11 and increasing the number of LED elements used in the first LED unit 11, the number of LED elements having a long lighting time can be increased and the variation in lighting can be reduced. Benefits are gained. Such an example is shown in FIG. In the LED lighting device 500 shown in this figure, the number of LED packages constituting the first LED unit 11 is six, and the number of LED packages used in the other second to fourth LED units is two. As a result, the first LED unit 11 is three times as many as the other LED units, and the first LED unit 11 alone constitutes half of the number of LED elements, the number of LED elements having a long lighting time is increased, and the LED having a short lighting time. By reducing the number of elements, variations in lighting can be made inconspicuous.
(Example 3)

As described above, each LED unit is turned on periodically by repeatedly turning on and off, and the lighting time varies depending on the LED unit. In the above example, the first LED unit 11, the second LED unit 12, the third LED unit 13, and the fourth LED unit 14 are turned on in order in accordance with an increase in the input voltage that is full-wave rectified by the rectifier circuit 2. As the voltage drops, the fourth LED unit 14, the third LED unit 13, the second LED unit 12, and the first LED unit 11 are turned off in this order. For this reason, the lighting time of the LED unit is the first LED unit 11> the second LED unit 12> the third LED unit 13> the fourth LED unit 14, and only the specific LED unit has a longer lighting time, the specific LED unit There is a possibility that the lighting unevenness that only the lighting time becomes short occurs. In particular, when the LED portions are arranged in order, the pattern of turning on and off is gradually repeated, and the user may perceive such a pattern. Therefore, it is conceivable to disperse such lighting patterns so as not to be perceived, approaching more uniform lighting. A light emitting diode driving apparatus 600 according to such an example is shown in FIG. In the circuit example shown in this figure, the fourth current detection transistor 34C is used as the drive element control means 5.
(LED division part 16)

  Here, utilizing the fact that the lighting time of the first LED unit 11 is longer than the other LED units, the first LED unit 11 is divided into a plurality of LED dividing units 16, and each LED dividing unit 16 is The second LED unit 12, the third LED unit 13, and the fourth LED unit 14 are directly connected. In this way, by dividing the first LED part with the longest lighting time into the LED dividing parts 16 and arranging them between the other LED parts, the uneven lighting time is suppressed and the lighting is brought closer to uniform lighting. It is possible to make it difficult for the user to perceive the difference. In addition, it is possible to obtain an advantage that the heat generated by the lighting of the LED elements can be easily radiated uniformly by arranging the first LED portions having the longest lighting time and the large amount of heat generation.

  Furthermore, by arranging the LED dividing section 16 obtained by dividing the first LED section 11 into a plurality of LED sections, an effect of reducing loss can be obtained as compared with the circuit example of FIG. That is, in the example of FIG. 3, since a plurality of bipolar transistors as current control means are connected in series on the control line CL and connected in a ladder shape to the output line OL, as shown in FIG. In addition, an equal voltage is applied to the blocks of the control line CL and the output line OL connected in parallel. There is no problem if the LED section is lit, in other words, if the first to third means FET is OFF, but if the input voltage drops gradually and the FET is turned ON, the bypass As a result of the current flowing through the path and the LED unit not being energized, no voltage drop due to the LED unit occurs. In other words, the voltage drop of the output line OL is partially lost. In other words, the voltage drop of the bypass circuit is lost. Therefore, in order to match the voltage of the control line CL, other than the output line OL. A voltage is newly applied to the part. Here, if the voltage Vce of the bipolar transistor in the control line CL is 4 V, for example, it is necessary to consume a voltage equivalent to 4 V in the output line OL. In FIG. Nevertheless, power is consumed by the FET. This loss occurs every period in each FET. Therefore, in order to reduce such a useless loss of the FET, the LED dividing unit 16 is arranged on the output line OL as shown in FIG. As a result, as a result of the LED dividing unit 16 acting as a resistance component and carrying the voltage, the voltage at the FET can be brought close to 0 V, and an advantage that loss, that is, generation of heat can be avoided can be obtained.

This problem does not occur in a circuit in which LED elements that are not multi-stage circuits are connected in series, or in a circuit in which current control means are connected in parallel even in a multi-stage circuit, as shown in FIG. 3 on a common control line CL. This is a problem peculiar to a multistage circuit caused by arranging them in series. And by arrange | positioning the LED division | segmentation part 16 before and after the branch point of each bypass path | route like FIG. 11, it can eliminate, without adding extra parts. Further, as described above, it can contribute to the dispersion and uniformity of the light emission pattern and the uniformity of heat dissipation, and is effective for such a multistage circuit.
Example 4

  In the circuit example of FIG. 11 described above, the control line CL in which the current control means is connected in series is completely connected to the output line OL and the ground line GL. In this configuration, when the automatic blinking circuit 50 operates to turn off the LED assembly 10, a current flows through a path indicated by a solid line arrow in FIG. At this time, the LED driving means 3 is OFF, and the LED assembly 10 should not be energized originally. However, in the configuration in which the LED dividing section 16 is provided between the bypass paths as shown in FIG. 14, a path for energization is formed through the input control means 53 instead of the LED drive means 3. 14, a minute current flows along a path indicated by a broken line. In other words, the LED dividing unit 16 in the LED assembly 10 may be slightly lit even though the LED driving unit 3 is OFF. is there.

  Therefore, as a circuit example for avoiding such a situation, a light emitting diode driving device 700 that can reliably turn off the LED driving means 3 is shown in FIG. A light-emitting diode driving device 700 shown in this figure has the same configuration as that of FIG. 11 and has a control line CL in parallel with the output line OL halfway, and is shared with the output line OL halfway. Specifically, the control line CL is connected to the output line OL on the upstream side of the LED dividing unit 16 at the final stage. As a result, the current of the control line CL is finally integrated with the output line OL, and the LED driving means 3 is energized. In other words, the current in the bypass path blocks the path that flows to the input control means 53.

On the other hand, a bipolar transistor for controlling the LED driving means 3 is provided on the second control line CL2 separate from the control line CL. As a result, since the path through which the current of the bypass path flows to the input control means 53 is interrupted, the LED assembly 10 can be turned off by turning off the LED driving means 3 regardless of the ON state of the current control means 53. .
(Smoothing circuit 50)

Furthermore, the light emitting diode driving device can include a smoothing circuit at the output stage of the rectifier circuit 2. The smoothing circuit prevents the discharge from starting until the input voltage drops to a predetermined capacitor discharge start voltage.
(Example 5)

  In the above smoothing circuit, an FET is used as a discharge element. In this case, since the voltage Vds at the time of ON is relatively large, the loss is large and the heat generation amount is also large, and heat dissipation must be taken into consideration. Therefore, this problem can be solved by using a thyristor instead of the FET as the discharge element. An example of such a circuit is shown in FIG. 16 as a light-emitting diode driving device 800 according to the fifth embodiment. A smoothing circuit 50B shown in this figure serves as a charging path for charging the smoothing capacitor 51B, and includes a resistor 52B and a discharge blocking diode 53B interposed in series between the rectifier circuit 2 and the + side of the smoothing capacitor 51B. Is provided. As a discharge path for discharging the smoothing capacitor 51B, a thyristor is provided as a discharge element 55B connected in parallel with the resistor 52B and the discharge blocking diode 53B with respect to the connection point CP. A Zener diode is connected to the gate of the thyristor. As described above, the drive circuit of the thyristor can be greatly simplified, and a bipolar transistor or the like can be eliminated from the smoothing circuit. Furthermore, since the thyristor itself has a rectifying action, a rectifying element such as a diode for regulating the charging / discharging path can be eliminated, and the number of parts can be greatly reduced.

  Furthermore, according to the circuit of FIG. 16, the loss of the discharge element can be reduced. For example, in the FET, the voltage Vds at the time of ON is about 4V, but in FIG. 16, the voltage at the time of ON of the thyristor can be suppressed to about 1V. As a result, the loss can be reduced, the heat dissipation can be improved and the heat countermeasure can be simplified as much as no extra heat is generated. According to the experiments by the present inventors, in the example of the smoothing circuit using the FET, the loss of the FET is 1.3 W and the substrate loss is 2.4 W. In the example of FIG. The substrate loss was reduced to 3 W and 1.2 W, and the usefulness of the above configuration was confirmed.

  Since the light emitting diode driving device as described above includes an LED element, the LED device and the driving circuit thereof are arranged on the same wiring board, so that the lighting device or the lighting that can be turned on by turning on the household AC power supply It can be used as an instrument.

  The light emitting diode driving device of the present invention can be suitably used as a lighting device, particularly a street lamp.

100, 200, 300, 500, 600, 700, 800 ... LED driving device 1 ... LED package 2 ... rectifier circuit 3 ... LED driving means 4 ... current detecting means; 4A ... first LED current detecting resistor; 4B ... second LED current detection resistor 4C ... third LED current detection resistor; 4D ... fourth LED current detection resistor 5 ... drive element control means 10 ... LED assembly 11 ... first LED unit 12 ... second LED unit 13 ... third LED unit 14 ... 4th LED part 16 ... LED division | segmentation part 17 ... Protection resistance 19 ... Bypass capacitor 21 ... 1st means; 21A, 21B ... 1st LED current control transistor 22 ... 2nd means; 22A, 22B ... 2nd LED current control Transistor 23 ... Third means; 23A, 23B ... Third LED current control transistor 24B ... Fourth LED current control transistor 27 ... First gate Resistor 28 ... second gate resistor 29 ... third gate resistor 31 ... first current control means; 31A, 31B ... first current detection transistor 32 ... second current control means; 32A, 32B ... second current detection transistor 33 ... first Three current control means; 33A, 33B ... third current detection transistors 34A, 34B, 34C ... fourth current detection transistors 36, 36B ... first transistor load resistors 37, 37B ... second transistor load resistors 38, 38B ... third transistor Load resistors 39, 39B ... Fourth transistor load resistor 41 ... First base resistor 42 ... Second base resistor 43 ... Third base resistor 44 ... Protection element 45 ... Protection switching element 50 ... Automatic flashing circuit 50B ... Smoothing circuit 51 ... Illuminance detection means 52 ... input voltage detection means; 52A ... input voltage detection resistor; 52B ... resistance 53 ... input Means: 53A ... Input current control transistor 55 ... Illuminance detection collector resistor 55B ... Discharge element 56 ... Illuminance detection emitter resistor 57 ... High frequency component removing capacitor 58 ... Input voltage detection base resistor 75 ... Case portion 76 ... Fixed portion 77 ... Sensor Part AP ... AC power supply; CP ... Connection point BP1 ... First bypass route; BP2 ... Second bypass route; BP3 ... Third bypass route OL ... Output line; CL ... Control line; CL2 ... Second control line CR ... Longitudinal line LL ... current limit line; GL ... ground line

Claims (7)

A rectifier circuit (2) that can be connected to an AC power source and rectifies the AC voltage of the AC power source,
A first LED section (11) having at least one LED element connected to the rectifier circuit (2);
A second LED part (12) having at least one LED element connected to the first LED part (11);
A third LED part (13) having at least one LED element connected to the second LED part (12);
A first means (21) connected in parallel with the second LED section (12), for controlling the amount of electricity to the first LED section (11);
A second means (22) connected in parallel with the third LED part (13), for controlling the amount of electricity to the first LED part (11) and the second LED part (12);
First current control means (31) for controlling the first means (21);
Second current control means (32) for controlling the second means (22);
With
The light emitting diode driving apparatus, wherein the first current control means (31) and the second current control means (32) are connected in series. The light-emitting diode driving device according to claim 1,
The first LED part (11) is divided into a plurality of LED dividing parts (16),
The LED dividing section (16) is connected to at least the upstream side and / or the downstream side of the second LED section (12), or the upstream side and / or the downstream side of the third LED section (13). A light emitting diode driving device characterized by the above. The light-emitting diode driving device according to claim 2,
The plurality of LED units are connected in series on an output line (OL),
The second LED unit (12) or the third LED unit (13) is connected to the downstream side of the LED dividing unit (16) connected on the output line (OL),
And the output line (OL) is branched at the interface of the connection between the LED dividing section (16) and the second LED section (12) or the third LED section (13). A light emitting diode driving device comprising a first means or a second means connected to the top. The light emitting diode driving device according to claim 3,
The second LED part (12) or the third LED part (13) is connected to the upstream side of at least one of the LED dividing parts (16),
And the output line (OL) is branched at the interface of the connection between the LED splitting part (16) and the second LED part (12) or the third LED part (13), and on the branch line A light-emitting diode driving device comprising a first means or a second means connected. The light emitting diode driving device according to claim 4,
As the current detection means (4) for detecting the amount of current flowing on the output line (OL) in which the plurality of LED units are connected in series, a plurality of sub current detection means are provided on the output line (OL). Connected,
Each sub-current detection means is between the first LED part (11) and the second LED part (12) and / or between the second LED part (12) and the third LED part (13), A light emitting diode driving device characterized by being connected in series. A light-emitting diode driving device according to any one of claims 2 to 5,
The LED dividing section (16)
Along with the rise of the input voltage rectified by the rectifier circuit (2), the second LED part (12) and the third LED part (13) are turned on before the input voltage is lowered, and the second LED A light emitting diode driving device characterized in that the LED is turned off later than the unit (12) and the third LED unit (13). The light emitting diode driving device according to any one of claims 2 to 6, further comprising:
A fourth LED part (14) having at least one LED element connected to the third LED part (13);
Third means for controlling the amount of current supplied to the first LED part (11), the second LED part (12) and the third LED part (13) connected in parallel with the fourth LED part (14) (23)
Third current control means (33) for controlling the third means (23);
With
The LED drive unit according to claim 1, wherein the LED dividing unit (16) is disposed between the third LED unit (13) and the fourth LED unit (14).

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