JP2013004396A - Led lighting device and luminaire - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an LED lighting device which is composed in such a way that when a DC/DC converter is inoperative, a discharge resistor is connected to a capacitor in order to prevent efficiency reduction or heat generation in the LED lighting device, and that the possibility of getting an electric shock when replacing LEDs is eliminated.SOLUTION: In an LED lighting device 9 comprising a rectification circuit 2 which rectifies AC voltage, a DC/DC converter 3 which, upon receiving the output of the rectification circuit 2, supplies limited current to an LED 5, a capacitor 4 which smooths the output of the DC/DC converter 3, and a series circuit composed of a discharge resistor 6 and a switch 8b which are connected in parallel to the capacitor 4, a construction is adopted that the switch 8b consists of a relay switch 8 of normally closed contact type equipped with an operation coil 8a, the operation coil 8a being connected to the DC/DC converter 3 so that a voltage associated with the operation of the DC/DC converter 3 will be supplied to the operation coil 8a, and that the switch 8b is closed when the DC/DC converter 3 is inoperative.

Description

  The present invention relates to an LED lighting device and an illumination device using the LED lighting device.

  FIG. 4 shows a block diagram of a conventional LED lighting device (for example, Patent Document 1). The LED lighting device 10 includes a rectifier circuit 2 that rectifies an AC voltage from an AC power source 1 (for example, a commercial power source), a DC / DC converter 3 that limits an output from the rectifier circuit 2 to a DC current optimum for the LED 5, and a DC A capacitor 4 that smoothes the output of the DC converter 3 is provided. An LED 5 (an array of LEDs) is detachably mounted on the LED lighting device 10 at output terminals T3 and T4.

  The operation of the LED lighting device of FIG. 4 will be described with reference to FIG. The rectifier circuit 2 converts the alternating voltage (a) into a full-wave rectified voltage (b). The DC / DC converter 3 acts as a step-down converter and outputs a pulsating voltage in which the amplitude of the full-wave rectified voltage (b) is reduced. When such a pulsating voltage is applied to the LED 5 as it is, no current flows through the LED 5 near a voltage of 0 V, and thus a light extinction period occurs at a frequency twice that of the AC power supply 1. This light-off period is not preferable because it is perceived as flicker by human eyes. In order to smooth the output pulsating voltage of the DC / DC converter 3 and prevent flickering, a capacitor having a relatively large capacity of several μF to several hundred μF is used as the capacitor 4. The voltage (c) smoothed by the capacitor 4 is applied to the LED 5 and the LED current (d) flows. If the capacitor 4 is connected to the previous stage of the DC / DC converter 3, a so-called capacitor input type circuit configuration is obtained, which is not preferable because the input power factor decreases and the power harmonic current increases. Therefore, it is desirable to connect the capacitor 4 to the subsequent stage of the DC / DC converter 3 as shown in FIG.

  By the way, an electric current does not flow to the LED and no light is emitted unless a voltage higher than the forward voltage of the LED is applied. In the case of a white LED often used for illumination, the forward voltage is about 3.5V. When LEDs are connected in series, a voltage equal to or greater than the number of LEDs × forward voltage (hereinafter referred to as “total forward voltage”) is required as the output voltage of the DC / DC converter 3. In other words, when the output voltage of the DC / DC converter 3 falls below its total forward voltage, no current flows through the LED 5.

  Here, in the LED lighting device 10, when the AC power supply 1 is turned off from the lighting state and the LED 5 is turned off, the DC / DC converter 3 is stopped and the voltage charged in the capacitor 4 is equal to the total forward voltage. It is discharged by the LED 5 until it falls below, but when it falls below the total forward voltage, it remains in the capacitor 4 without being discharged. Since a step-down converter circuit as shown in FIGS. 3A, 3B, etc. is generally used for the DC / DC converter 3, the voltage of the capacitor 4 is not discharged by the DC / DC converter 3 when the operation is stopped.

  Although the charging voltage remaining in the capacitor 4 is gradually spontaneously discharged, the capacitor 4 has a relatively large capacity of several μF to several hundred μF, and thus is charged for a long time. When the user replaces the LED 5 in this charged state, if the user accidentally touches the output terminals (T3, T4) of the LED lighting device 10, there is a possibility of electric shock, which is dangerous. In particular, a user of a lighting device equipped with such an LED lighting device does not expect that there is a risk of electric shock when the AC switch S of the AC power source 1 (commercial power source) is turned off and the LED 5 is turned off. Therefore, it is even more dangerous. Therefore, as shown in FIG. 6, if the discharge resistor 6 is connected in parallel to the capacitor 4, the voltage remaining in the capacitor 4 after the LED is turned off can be discharged.

JP 2008-166192 A JP 2010-55824 A

  However, when a discharge resistor is connected to a smoothing capacitor as shown in FIG. 6, power is consumed by the discharge resistor even during normal lighting, so that the input power increases and the efficiency of the LED lighting device decreases, and the discharge resistor is dissipated. There is a problem that a configuration is required to do this. Therefore, the discharge resistor needs to be connected to the capacitor only when the LED is turned off. Patent Document 2 discloses a configuration in which a discharge switch connected to a discharge resistor is turned on by a signal from a control circuit when there is no load (that is, when an LED is not connected). However, in such a configuration, when the input power is cut off, it is not possible to secure a power source for the control signal in the LED lighting device, and it is not possible to turn on the discharge switch to connect the discharge resistor.

  Therefore, the present invention prevents the LED lighting device from being reduced in efficiency and heat generation by connecting the discharge resistor to the capacitor even when the control power supply cannot be secured when the DC / DC converter is not operating, such as when the input power is shut off. In addition, an object is to provide a configuration that eliminates the possibility of electric shock during LED replacement.

  A first aspect of the present invention is a rectifier circuit that rectifies an alternating voltage, a DC / DC converter that receives an output of the rectifier circuit and supplies a limited current to an LED, and an output of the DC / DC converter that is smoothed An LED lighting device having a capacitor and a series circuit of a discharge resistor and a switch connected in parallel to the capacitor, the switch comprising a normally closed contact type relay switch having an operation coil, and the operation coil having a DC / DC converter The LED lighting device is configured such that the operation coil is connected to the DC / DC converter so that a voltage related to the operation of the DC / DC converter is applied, and the switch is closed when the DC / DC converter is not operating.

Here, the operation coil is connected between the input terminals of the DC / DC converter.
Moreover, it is good also as a structure by which an operation coil is connected in a DC / DC converter so that the voltage generated resulting from the switching operation of the switching element which comprises a DC / DC converter may be applied to an operation coil.

  The 2nd side of the present invention is the lighting installation provided with the LED lighting device of the above 1st side, the LED which was detachably attached to the LED lighting device, and the LED lighting device and the instrument main part which holds the LED.

It is a figure which shows the LED lighting device of this invention. It is a figure which shows the LED lighting device by the Example of this invention. It is a figure which shows an example of a general DC / DC converter. It is a figure which shows an example of a general DC / DC converter. It is a figure explaining the modification of this invention. It is a figure which shows the conventional LED lighting device. It is a figure explaining operation | movement of a LED lighting device. It is a figure which shows the conventional LED lighting device.

<Basic configuration>
FIG. 1 shows an LED lighting device of the present invention. The LED lighting device 9 includes a rectifier circuit 2 that rectifies an AC voltage from an AC power source 1 (for example, a commercial power source), and a DC / DC converter 3 that receives an output of the rectifier circuit 2 and supplies a limited current to the LED 5. , A capacitor 4 for smoothing the output of the DC / DC converter 3, a series circuit of a discharge resistor 6 and a switch 7b connected in parallel to the capacitor 4, and a DC / DC converter operation detecting means 7a for controlling the switch 7b. The DC / DC converter operation detection means 7a and the discharge switch 7b constitute a DC / DC converter operation detection switch 7.

  In FIG. 1, the rectifier circuit 2, the DC / DC converter 3, the capacitor 4 and the discharge resistor 6 are the same as those described in FIG. Further, the voltage and current waveforms of each part are the same as those shown in FIG.

  The LED lighting device 9 includes input terminals T1 and T2 that receive a voltage from the AC power source 1, and output terminals T3 and T4 to the LED 5 (LED array). The LED 5 is detachably connected to the LED lighting device 9 at the output terminals T3 and T4. The lighting device is configured by the LED lighting device 9, the LED 5, and the fixture main body (not shown) that holds the LED lighting device 9 and the LED 5.

  The switch 7b is a normally closed contact type switch that is closed when there is no control signal from the DC / DC converter operation detecting means 7a. Therefore, when the AC power supply 1 is turned on and the DC / DC converter 3 is operating, the switch 7b is opened by the control signal from the DC / DC converter operation detecting means 7a. After that, when the AC power source 1 is shut off and the DC / DC converter 3 becomes inoperative, the switch 7b is closed due to the absence of the control signal from the DC / DC converter operation detecting means 7a.

  With the above configuration, the discharge resistor 6 is not connected while the LED is lit, so that no wasted power is generated and therefore no heat is generated. Then, since the discharge resistor 6 is immediately connected after the LED is turned off, the charging voltage remaining in the capacitor 4 is discharged through the discharge resistor 6. As a result, no voltage is generated between the output terminals T3 and T4 after the LED is turned off, and the LED can be replaced safely.

<Example>
FIG. 2 shows an LED lighting device according to the first embodiment of the present invention. Under the concept of the basic configuration described above, the LED lighting device 9 of this embodiment includes a normally closed contact type (b contact type) relay switch 8 including an operation coil 8a and a switch 8b, and the switch 8b is connected to the discharge resistor 6. Connected in series. That is, the operation coil 8a is used as an example of the DC / DC converter operation detecting means 7a, and a voltage related to the operation of the DC / DC converter 3 is applied to the operation coil 8a. In the present embodiment, the operation coil 8 a is connected between the input terminals of the DC / DC converter 3 so that the input voltage to the DC / DC converter 3 is applied.

  Therefore, when the AC power supply 1 is turned on and an input voltage is applied to the DC / DC converter 3, an exciting current flows through the operation coil 8a, thereby opening the switch 8b. Thereafter, when the AC power supply 1 is shut off and no input voltage is applied to the DC / DC converter 3, the control signal from the operation coil 8a disappears, and the switch 8b is closed. As a result, the switch 8b is closed when the DC / DC converter 3 is not operating, and the charging voltage remaining in the capacitor 4 is discharged via the discharge resistor 6.

  With the above configuration, the discharge resistor 6 is not connected while the LED is lit, so that no wasted power is generated and therefore no heat is generated. The power consumed by the operation coil 8a of the relay switch 8 is much smaller than the power when the discharge resistor 6 is always connected. Since the discharge resistor 6 is immediately connected after the LED is turned off, the charging voltage remaining in the capacitor 4 is discharged immediately after the LED is turned off. As a result, no voltage is generated between the output terminals T3 and T4 after the LED is turned off, and the LED can be safely replaced after the LED is turned off.

  An illumination device can be configured by including the LED lighting device 9, the LED 5 that is detachably mounted on the LED lighting device 9, and the fixture main body (not shown) that holds the LED lighting device 9 and the LED 5. By mounting the LED lighting device 9 described above, it is possible to provide an illumination device that can safely replace the LED after the AC power source 1 is shut off and turned off.

<Modification>
In the above embodiment, an example in which the operation coil 8a of the relay switch 8 is connected between the input terminals of the DC / DC converter 3 has been shown, but it occurs due to the switching operation of the switching elements constituting the DC / DC converter 3. A voltage to be applied may be applied to the operation coil 8a.

  For example, when a general step-down converter circuit as shown in FIG. 3A or 3B is used as the DC / DC converter 3, the current transformer CT is inserted into the path a or b in FIG. 3A or the path c in FIG. 3B. As shown, the CT output may be applied to the operation coil 8a. The DC / DC converter 3 in FIG. 3A includes a transistor 31 (switching element), a control circuit 32 that performs PWM control of the transistor 31, a current limiting coil 33, a diode 34, and a detection resistor 35. The control circuit 32 includes: The transistor 31 is PWM-controlled at a predetermined frequency (for example, about several tens of kHz) so that the voltage generated in the detection resistor 35, that is, the LED current becomes constant at a predetermined value. 3B includes a transistor 31 (switching element), a control circuit 32 that performs PWM control of the transistor 31, a transformer 36, and a diode 37. The control circuit 32 sets the transistor 31 to a predetermined frequency (for example, several PWM control at about 10 kHz).

  In the case of the above modification, the control circuit 32 is stopped and the transistor is turned off when the AC switch S is closed and turned off by remote control, that is, the input voltage is applied to the DC / DC converter 3. Even when 31 is in an open state, no voltage is applied to the operation coil 8a, and the switch 8b can be closed. Therefore, according to the configuration of the modified example, it is possible to safely replace the LED regardless of whether the LED extinguishing state is due to the interruption of the AC power supply 1 or the extinguishing control by the remote controller.

In the above embodiment, the operation of the DC / DC converter 3 is monitored by the operation coil unit of the relay switch. However, the operation is not limited to the relay switch, and a photocoupler using a semiconductor may be used.
The above embodiment can also be applied to an LED lighting device using a DC / DC converter other than the circuit configuration shown in FIG. 3A, and the configuration of the modified example is also applied to coils constituting the DC / DC converter. can do.

  As described above, in the LED lighting device and the lighting device using the LED lighting device, the discharge resistor is connected to the capacitor when the DC / DC converter is not in operation to prevent the LED lighting device from being reduced in efficiency and heat generation, and when the LED is replaced. The possibility of electric shock can be eliminated.

2. 2. Rectifier circuit DC / DC converter4. Capacitor 5. LED
6). 6. Discharge resistance DC / DC converter operation detection switch 7a. DC / DC converter operation detecting means 7b. Switch 8. Relay switch 8a. Operating coil 8b. Switch 9. LED lighting device

Claims (4)

An LED lighting device,
Rectifier circuit for rectifying AC voltage,
A DC / DC converter for receiving the output of the rectifier circuit and supplying a limited current to the LED;
A capacitor for smoothing the output of the DC / DC converter, and a series circuit of a discharge resistor and a switch connected in parallel to the capacitor;
The switch comprises a normally closed contact type relay switch having an operation coil, and the operation coil is connected to the DC / DC so that a voltage generated in connection with the operation of the DC / DC converter is applied to the operation coil. An LED lighting device connected to a DC converter and configured to close the switch when the DC / DC converter is not operating.   The LED lighting device according to claim 1, wherein the operation coil is connected between input terminals of the DC / DC converter.   2. The LED lighting device according to claim 1, wherein the operating coil is applied to the operating coil such that a voltage generated due to a switching operation of a switching element constituting the DC / DC converter is applied to the operating coil. LED lighting device connected in the converter. LED lighting device according to any one of claims 1 to 3,
An LED that is detachably mounted on the LED lighting device, and an illumination device that includes the LED lighting device and a fixture main body that holds the LED.

Images