JP2016024919A - Led driving device and led lighting device - Google Patents

Abstract

An LED drive device that can be housed in a straight tube type casing, can be reduced in size and weight, and can reduce noise. A circuit board PCB that can be housed in a straight tube-type housing and on which wiring patterns P1 to P6 are formed, a DC power source that is connected to the wiring pattern and has a rectifying unit and a first capacitor C1, and a wiring pattern And a non-insulating converter having a switching element SW, a reactor L, a diode D, and a second capacitor C2, and at least the first capacitor, the switching element, and the reactor when the switching element is conductive The first current loop LP1 is formed through the wiring pattern, and at least when the switching element is non-conducting, at least the reactor, the diode, and the second capacitor form the second current loop LP2 through the wiring pattern. The loop length is set to less than twice the length of the second current loop. [Selection] Figure 1

Description

  The present invention relates to an LED driving device that drives a light emitting diode (LED), and more particularly to an LED driving device and an LED lighting device that can reduce radiation noise and conduction noise.

  Conventionally, a built-in LED lighting device is known (Patent Document 1). This built-in power supply type LED illuminating device has an advantage that it can be easily replaced with an existing fluorescent lamp, and the installation work cost can be reduced as compared with an external power supply type.

  The LED illumination device includes an LED light emitting unit and an LED driving device that drives the LED light emitting unit. In the LED lighting device with a built-in power source, the LED light emitting unit and the LED driving device are housed in an elongated tube made of glass or resin. In addition, it is necessary to reduce the weight of the LED driving device in order to prevent the LED lighting device from falling off.

  For this reason, the circuit configuration (component arrangement) of the LED drive device is subject to spatial restrictions such as the length, width, and component height of the circuit board (PCB), and the number of components used in the LED drive device is reduced. It is required to reduce the size and weight.

JP 2010-92990 A

  Further, the LED driving device is also required to have electrical characteristics. In particular, noise generated in the LED driving device has an influence such as radio wave interference on peripheral devices of the LED lighting device. For this reason, the countermeasure which arrange | positions a noise filter and a shielding material with respect to an LED drive device can be considered. However, disposing a noise filter and a shielding material is in a trade-off relationship with hindering reduction in size and weight of the LED driving device.

  An object of the present invention is to provide an LED driving device and an LED lighting device that can be accommodated in a straight tube type casing, can reduce noise, and can be easily reduced in size and weight.

  The LED driving device of the present invention includes a circuit board that can be housed in a straight tube-type housing and has a wiring pattern formed thereon, a DC power source that is connected to the wiring pattern and includes a rectifying unit and a first capacitor, and the wiring pattern. And a non-insulating converter having a switching element, a reactor, a diode, and a second capacitor, and at least when the switching element is conductive, at least the first capacitor, the switching element, and the reactor. Forming a first current loop through the wiring pattern, and at least when the switching element is non-conductive, at least the reactor, the diode, and the second capacitor form a second current loop through the wiring pattern. The length of the first current loop is set to be less than twice the length of the second current loop. And said that you are.

  According to the present invention, since the length of the first current loop is set to be less than twice the length of the second current loop, it can be accommodated in a straight tube type casing, and noise can be reduced and easy. It is possible to provide an LED driving device and an LED lighting device that can be reduced in size and weight.

It is a circuit pattern schematic diagram of the LED drive device according to the first embodiment of the present invention, showing a first current loop when the switching element is on. It is a circuit pattern schematic diagram of the LED drive device according to the first embodiment of the present invention, showing a second current loop when the switching element is OFF. It is a circuit diagram of the LED drive device which concerns on Example 1 of this invention. It is a figure which shows the electric field strength with respect to the frequency of the radiation noise of the LED drive device which concerns on Example 1 of this invention. It is a figure which shows the disturbance wave voltage with respect to the frequency of the conduction noise of the LED drive device which concerns on Example 1 of this invention. It is a circuit pattern schematic diagram of a conventional LED driving device, and is a diagram showing a first current loop when a switching element is on. It is a circuit pattern schematic diagram of a conventional LED driving device, and is a diagram showing a second current loop when the switching element is off. It is a figure which shows the electric field strength with respect to the frequency of the radiation noise of the conventional LED drive device.

  Hereinafter, an LED drive device and an LED illumination device according to an embodiment of the present invention will be described in detail with reference to the drawings.

  First, the present inventor can reduce radiation noise and conduction noise and reduce countermeasure parts such as a noise filter by changing the circuit board pattern in a non-insulated step-down LED driving device that can be embedded in a straight tube. I found From the experimental results, the point of pattern change is to reduce the change between the length of the current loop when the switching element is on (when conducting) and the length of the current loop when the switching element is off (when not conducting).

  Hereinafter, a non-insulated step-down LED driving device capable of incorporating a straight pipe according to the first embodiment will be described with reference to FIGS. FIG. 1 is a schematic circuit pattern diagram of the LED drive device according to the first embodiment of the present invention, and shows a first current loop when the switching element is on. FIG. 2 is a schematic circuit pattern diagram of the LED drive device according to the first embodiment of the present invention, and is a diagram illustrating a second current loop when the switching element is off.

  FIG. 3 is a circuit diagram of the LED driving apparatus according to Embodiment 1 of the present invention. The LED driving device shown in FIG. 3 is a non-insulated step-down type. This LED driving device includes an AC power supply Vac, a full-wave rectification unit DB, a first capacitor C1, a switching element SW, a diode D, a reactor L, and a second capacitor C2.

  The full-wave rectifier DB and the first capacitor C1 constitute a DC power supply according to the present invention. The switching element SW, the reactor L, the diode D, and the second capacitor C2 constitute a non-insulating converter of the present invention, and steps down the first DC voltage of the first capacitor C1 and converts it to a second DC voltage.

  The LED illumination device includes an LED driving device and an LED light emitting unit LED connected in parallel to the second capacitor C2. The switching element SW is composed of, for example, a MOSFET.

  The circuit board PCB shown in FIGS. 1 and 2 can be stored in a straight tube type casing (not shown), and conductive wiring patterns P1 to P6 are formed. Each component such as the first capacitor C1, the switching element SW, the diode D, the reactor L, and the second capacitor C2 of the LED driving device shown in FIG. 3 is a wiring pattern formed on the circuit board PCB shown in FIGS. It arrange | positions at P1-P6 and is soldered to wiring pattern P1-P6.

  The connection between the wiring patterns of each component described above follows the circuit diagram of the LED driving device shown in FIG. Specifically, as shown in FIGS. 1 and 2, the first capacitor C1 is connected to the wiring pattern P1 and the wiring pattern P2. The switching element SW is connected to the wiring pattern P1 and the wiring pattern P3.

  The diode D is connected to the wiring pattern P2 and the wiring pattern P3. Reactor L is connected to wiring pattern P5 and wiring pattern P6. The second capacitor C2 is connected to the wiring pattern P6 and the wiring pattern P2.

  In FIG. 3, when the switching element SW is turned on, a current flows through a path of the first capacitor C1, the switching element SW, the reactor L, the second capacitor C2, and the first capacitor C1. At this time, in the wiring pattern shown in FIG. 1, when the switching element SW is turned on, at least the first capacitor C1, the switching element SW, and the reactor L form the first current loop LP1 via the wiring patterns P1 to P6.

  In FIG. 3, when the switching element SW is turned off, a current flows through a path of the reactor L → second capacitor C2 → diode D → reactor L. At this time, in the wiring pattern shown in FIG. 2, when the switching element SW is turned off, at least the diode D, the reactor L, and the second capacitor C2 form a second current loop LP2 via the wiring patterns P2 to P6.

  The length of the first current loop LP1 is set to be less than twice the length of the second current loop LP2. More specifically, the length of the second current loop LP2 is increased, and the length of the first current loop LP1 is set to 1.2 times the length of the second current loop LP2.

  FIG. 4 is a diagram showing the electric field strength with respect to the frequency of the radiation noise when the length of the first current loop LP1 is 1.2 times the length of the second current loop LP2. As shown in FIG. 4, both the horizontal radiation noise H and the vertical radiation noise V are less than the limit value Lm. In other words, the noise characteristics were improved as compared with the conventional LED driving device described later, and it was possible to meet the VCCI standard.

  FIG. 5 is a diagram illustrating an interference wave voltage with respect to the frequency of the conduction noise of the LED drive device according to the first embodiment of the present invention. As shown in FIG. 5, the conduction noise (peak) Vb is not more than the QP limit value L1. That is, since the conduction noise characteristic also conforms to the VCCI standard, noise countermeasure components such as a noise filter can be reduced.

(Conventional experiment)
Next, the experiment of the conventional example with respect to Example 1 is demonstrated. FIG. 6 is a schematic diagram of a circuit pattern of a conventional LED driving device, and shows a first current loop when the switching element is on. FIG. 7 is a schematic circuit pattern diagram of a conventional LED driving device, and shows a second current loop when the switching element is OFF. It is assumed that the circuit of the conventional LED driving device is the same as that shown in FIG.

  As shown in FIGS. 6 and 7, the first capacitor C1, the switching element SW, the diode D, the reactor L, and the second capacitor C2 are connected through wiring patterns P11 to P17.

  In the wiring pattern shown in FIG. 6, when the switching element SW is turned on, at least the first capacitor C1, the switching element SW, and the reactor L form a first current loop LP11 via the wiring patterns P11 to P17.

  In the wiring pattern shown in FIG. 7, when the switching element SW is off, at least the diode D, the reactor L, and the second capacitor C2 form the second current loop LP12 via the wiring patterns P13 to P17.

  The length of the first current loop LP11 is about 2.0 times the length of the second current loop LP12. FIG. 8 is a diagram showing the electric field strength with respect to the frequency of the radiation noise when the length of the first current loop LP11 is 2.0 times the length of the second current loop LP12. As shown in FIG. 8, both the horizontal radiation noise H and the vertical radiation noise V exceed the limit value Lm. That is, the noise characteristic is poor and does not conform to the VCCI standard.

(Comparative Example 1)
Next, the experiment of the comparative example 1 with respect to Example 1 is demonstrated. In order to reduce the area of the current loop, the length of the second current loop was shortened, and the length of the first current loop was about 3.0 times the length of the second current loop. Also in this case, the noise characteristic is deteriorated depending on the frequency band.

(Comparative Example 2)
Next, the experiment of the comparative example 2 with respect to Example 1 is demonstrated. Only the length of the first current loop was shortened, and the length of the first current loop was about 2.0 times the length of the second current loop. In this case, compared with Comparative Example 1, noise characteristics were improved in the entire frequency band.

  From the above experimental results, not only the area of the entire current loop but also the ratio between the length of the first current loop and the length of the second current loop, that is, the inductance of the current path when the switching element SW is on and the switching element SW It is presumed that reducing the change with the inductance of the current path at the time of off acts on noise reduction.

  As described above, according to the first embodiment of the present invention, the length LP1 of the first current loop is set to be less than twice the length of the second current loop LP2, and thus is accommodated in the straight tube type casing. It is possible to provide an LED driving device and an LED lighting device that can reduce noise and can be easily reduced in size and weight.

  In addition, this invention is not limited to the LED drive device and LED lighting apparatus which concern on Example 1 mentioned above. In the LED driving device and the LED lighting device according to the first embodiment, the step-down conversion unit as illustrated in FIG. 3 is applied. However, for example, the step-down conversion unit or the step-up / step-down conversion unit may be applied.

Vac AC power supply DB Full wave rectification unit C1 First capacitor SW Switching element D Diode L Reactor C2 Second capacitor LED LED light emitting units P1 to P5, P11 to P17 Wiring pattern LP1 First current loop LP2 Second current loop L1 QP limit value L2 AVE limit value Vb Conduction noise (peak)
V Vertical radiation noise H Horizontal radiation noise

Claims (4)

A circuit board that can be stored in a straight tube-type housing and on which a wiring pattern is formed;
A DC power source connected to the wiring pattern and having a rectifier and a first capacitor;
A non-insulating converter connected to the DC power source via the wiring pattern and having a switching element, a reactor, a diode, and a second capacitor;
At the time of the conduction of the switching element, at least the first capacitor, the switching element and the reactor form a first current loop through the wiring pattern,
At the time of non-conduction of the switching element, at least the reactor, the diode, and the second capacitor form a second current loop through the wiring pattern,
The length of the first current loop is set to be less than twice the length of the second current loop.   2. The LED driving device according to claim 1, wherein a length of the first current loop is set to 1.2 times or less of a length of the second current loop.   The LED driving device according to claim 1, wherein the non-insulating converter is a step-down converter. The LED driving device according to any one of claims 1 to 3,
An LED light emitting unit connected in parallel to the second capacitor;
A straight tube type LED lighting device.

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