JP4654891B2 - Lighting device and lighting device - Google Patents

Description

  The present invention relates to a lighting device and an illumination device using an organic EL element as a light source.

  In recent years, organic EL devices have been actively studied as thin solid-state light emitting devices. An organic EL device is a device in which a thin light emitting layer made of an organic compound is sandwiched between electrodes, and emits light when a voltage is supplied between the electrodes. The organic EL element can be configured as a thin and lightweight light-emitting element, and the driving voltage is about several to several tens of volts, which is lower than that of a discharge lamp that is a mainstream light source in the past, so that a lighting device can be configured at low cost. Application to thin and lightweight lighting fixtures can be expected. As a conventional lighting device using an organic EL element, there is one as described in Patent Document 1.

As shown in FIG. 6, this conventional example includes a converter means 20 that converts AC power supplied from an AC power source PS into DC power, and an organic EL element by turning on / off the DC current supplied from the converter means 20. Switching means 30 for intermittently supplying a forward current to 10 and control means for switching on / off of the switching means 30 at a switching frequency higher than that of the AC power supply PS and for controlling the on-duty ratio of the switching means 30 40, the on-duty ratio is controlled by the control means 40 so as to obtain a desired luminance value by an external dimming mechanism that can be adjusted to a desired luminance by a user or the like by a dial or the like, By turning on / off the switching means 30 in accordance with the on-duty ratio, the organic EL element 10 flashes and emits light. There. Here, since the switching means 30 performs switching at a frequency higher than that of the AC power supply PS, the flickering of luminance is prevented and the light emission life is improved. In addition, the control means 40 can variably control the on-duty ratio to obtain a desired luminance. Further, as described in Patent Document 2, it is known that applying a reverse voltage to the organic EL element 10 increases the lifetime of the element.
JP 2005-78828 A Japanese Patent No. 2663648

  However, in the above conventional example, since the organic EL element 10 blinks and emits light by turning on / off the switching means 30, the forward voltage and the reverse voltage are alternately applied to the organic EL element 10. Although the lifetime can be extended, there is a problem in that the output of the organic EL element 10 cannot be increased because the luminance of the organic EL element 10 is low.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a lighting device and a lighting device capable of extending the life of an element without reducing the luminance of the organic EL element.

  In order to achieve the above object, the invention of claim 1 is a lighting device for supplying a driving voltage to one or a plurality of organic EL elements, a direct current power supply means for outputting a desired direct current voltage, and a direct current power supply means. Drive voltage supply means for receiving output and supplying drive voltage to the organic EL element, detection means for detecting the stop of voltage supply of the DC power supply means, and reverse to the organic EL element when the voltage supply of the DC power supply means is stopped And reverse voltage supply means for supplying a polarity voltage.

  According to a second aspect of the present invention, in the first aspect of the invention, the reverse voltage supply means uses the residual charge of the capacitor provided at the output terminal of the DC power supply means when the voltage supply of the DC power supply means is stopped. A voltage having a reverse polarity is supplied to the EL element.

  According to a third aspect of the present invention, in the first or second aspect of the present invention, the drive voltage supply means connects the series circuit of the switching element, the first organic EL element, the inductance and the capacitor to the output terminal of the DC power supply means and The reverse voltage supply means is composed of first and second switching elements, and the first switching element is a switching of the drive voltage supply means. The second switching element is connected between the connection point between the second organic EL element of the drive voltage supply means and the diode and the power supply side terminal of the DC power supply means. The switching element of the drive voltage supply means is connected to the power supply side of the DC power supply means.

  According to a fourth aspect of the present invention, in the first or second aspect of the present invention, the driving voltage supply means connects the series circuit of the switching element, the first organic EL element, the inductance and the capacitor to the output terminal of the DC power supply means and The reverse voltage supply means is composed of first and second switching elements, and the first switching element is a switching of the drive voltage supply means. The second switching element is connected between the connection point between the second organic EL element of the drive voltage supply means and the diode and the ground side terminal of the DC power supply means. The switching element of the drive voltage supply means is connected to the ground side of the DC power supply means.

  The invention of claim 5 is characterized by comprising the lighting device according to any one of claims 1 to 4 and one or more organic EL elements.

  According to the first aspect of the present invention, since the DC power supply means for outputting a desired DC voltage is provided, a stable DC voltage can be supplied to the organic EL element, and therefore the luminance is higher than that in the case of flashing light emission. can do. In addition, when the output of the DC power supply means is received, the drive voltage supply means for supplying the drive voltage to the organic EL element, the detection means for detecting the stop of the voltage supply of the DC power supply means, and when the voltage supply of the DC power supply means is stopped And a reverse voltage supply means for supplying a reverse polarity voltage to the organic EL element, so that the reverse polarity voltage can be supplied to the organic EL element when the lighting device is turned off. Life can be extended.

  According to the second aspect of the present invention, the direct current power supply means has a reverse polarity to the organic EL element by utilizing the residual charge of the capacitor provided at the output terminal of the direct current power supply means when the voltage supply of the direct current power supply means is stopped. Since the voltage is supplied, there is no need to separately prepare a DC power supply for supplying a reverse polarity voltage, and the lighting device can be configured simply.

  According to the invention of claim 3, the drive voltage supply means connects the series circuit of the switching element, the first organic EL element, the inductance and the capacitor to the output terminal of the DC power supply means, and in parallel with the capacitor, the second organic The reverse voltage supply means includes first and second switching elements, and the first switching element is connected to the switching element of the drive voltage supply means and the ground of the DC power supply means. The second switching element is connected between the connection point of the second organic EL element and the diode of the drive voltage supply means and the power supply side terminal of the DC power supply means. Since the switching element of the drive voltage supply means is connected to the power supply side of the DC power supply means, the same effect as in the first aspect can be obtained.

  According to the invention of claim 4, the drive voltage supply means connects the series circuit of the switching element, the first organic EL element, the inductance and the capacitor to the output terminal of the DC power supply means, and the second organic in parallel with the capacitor. A series circuit of an EL element and a diode is connected, the reverse voltage supply means is composed of first and second switching elements, and the first switching element is a switching element of the drive voltage supply means and a power source of the DC power supply means. The second switching element is connected between the connection point of the second organic EL element and the diode of the drive voltage supply means and the ground side terminal of the DC power supply means, Since the switching element of the driving voltage supply means is connected to the ground side of the DC power supply means, the switching of the switching element of the driving voltage supply means can be easily switched on / off. Also it is possible to facilitate the second switching of the on / off switching element of the reverse voltage supply means.

  According to the invention of claim 5, it is possible to realize an illuminating device having the effect of any one of claims 1 to 4.

(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The present embodiment is an illumination device that includes an organic EL element EL1 and a lighting device that supplies a drive voltage to the organic EL element EL1, and the lighting device includes a DC power supply means 2 that outputs a desired DC voltage, The drive voltage supply means 3 that receives the output of the power supply means 2 and supplies the drive voltage to the organic EL element EL1, the detection means 4 that detects the stop of the voltage supply of the DC power supply means 2, and the voltage supply of the DC power supply means 2 It is comprised from the reverse voltage supply means 5 which supplies the voltage of reverse polarity to organic EL element EL1 when it stops (refer Fig.1 (a)). The input terminals of the DC power supply means 2 and the detection means 4 are connected to the AC power supply PS via the power switch SW, and voltage supply from the AC power supply PS and supply stop are performed by switching the power switch SW on / off. Switch.

  The DC power supply means 2 is composed of a rectifier circuit 2a and a step-down converter circuit 2b. The AC voltage VS from the AC power supply PS is full-wave rectified using a rectifier circuit 2a composed of a diode bridge, and rectified pulsating current. The voltage is smoothed by the smoothing capacitor C0, and the smoothed voltage is stepped down to a DC voltage V0 having a desired magnitude using the step-down converter circuit 2b and output to the drive voltage supply means 3 described later. As the step-down converter circuit 2b, for example, a step-down chopper circuit (see FIG. 2A), a forward converter circuit (see FIG. 2B), or a flyback converter circuit (see FIG. 2C) may be used. It is done. Since each circuit configuration and its operation are well-known techniques, description thereof is omitted here.

  A capacitor (not shown) is connected to the output terminal of the step-down converter circuit 2b. When the power switch SW is on, a DC voltage V0 is output between the capacitors. When the power switch SW changes from the on state to the off state, the capacitor is discharged, so that even after the power switch SW is turned off, the voltage is applied to the drive voltage supply means 3 by the residual charge of the capacitor for a certain period of time. Supply.

  The drive voltage supply means 3 receives the output voltage V0 from the direct current power supply means 2 and supplies the direct current drive voltage VD to the organic EL element EL1.

  The detection means 4 rectifies the AC voltage VS from the AC power supply PS by the diodes D1 and D2, smoothes the rectified pulsating voltage by the capacitor C1, and outputs the smoothed voltage to the reverse voltage supply means 5. It has become.

  The reverse voltage supply means 5 supplies a reverse voltage to the organic EL element EL1 when the output from the detection means 4 becomes a predetermined threshold value or less. Note that the voltage necessary for the operation of supplying the reverse voltage is secured by utilizing the residual charge of the capacitor provided in the step-down converter circuit 2b.

  The operation of this embodiment will be described below. When the power switch SW is on, the detection means 4 outputs a constant voltage value to the reverse voltage supply means 5, and during this time, the reverse voltage supply means 5 does not operate and the drive voltage supply means 3 is applied to the organic EL element EL1. A drive voltage VD is supplied. When the power switch SW is switched from the on state to the off state, the AC voltage VS from the AC power source PS is not supplied, so that the output voltage to the reverse voltage supply unit 5 gradually decreases as the capacitor of the detection unit 4 is discharged. When the output voltage from the detection unit 4 becomes a predetermined threshold value or less, the reverse voltage supply unit 5 supplies the reverse voltage to the organic EL element EL1 (see FIG. 1B).

  As described above, the DC power supply means 2 generates the DC voltage V0, and the drive voltage supply means 3 receives the generated DC voltage V0 and supplies the DC drive voltage VD to the organic EL element EL1. Compared to the case, the luminance can be increased, and when the power supply SW of the AC power supply PS is turned off, the reverse voltage supply means 5 receives the output of the detection means 4 and applies a reverse voltage to the organic EL element EL1. Since it is supplied, the lifetime of the organic EL element EL1 can be extended. Further, since the reverse voltage is supplied using the residual charge of the capacitor provided in the step-down converter circuit 2b, it is not necessary to prepare a DC power source for supplying the reverse voltage, and thus the lighting device has a simple configuration. can do.

(Embodiment 2)
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings. In addition, about the site | part which is common in Embodiment 1, a common number is attached | subjected and description is abbreviate | omitted. In this embodiment, two organic EL elements EL1 and EL2 are used, and the drive voltage supply means 3 outputs a series circuit of the switching element Q, the organic EL element EL1, the inductance L, and the capacitor C to the output of the DC power supply means 2. The reverse voltage supply means 5 is composed of two switching elements Q1 and Q2, and is connected to the end and connected in series with the capacitor C in parallel with the capacitor C. The switching element Q2 is connected between the switching element Q of the supply means 3 and the ground side terminal of the DC power supply means 2, and the switching element Q2 is connected to the connection point between the organic EL element EL2 and the diode D of the drive voltage supply means 3 and the DC power supply means 2. The switching element Q of the drive voltage supply means 3 is connected to the power supply side of the DC power supply means 2 (see FIG. 3). a)). The AC power supply PS, the power switch SW, the DC power supply means 2, and the detection means 4 are the same as those in the first embodiment, and are not shown here.

  The operation of this embodiment will be described below. When the power switch SW of the AC power supply PS is on, the output terminal of the DC power supply means 2 outputs the DC voltage V0, and the switching elements Q1 and Q2 of the reverse voltage supply means 5 are kept off. The switching element Q of the drive voltage supply means 3 is switched on and off alternately. In the on state, a current flows in the closed circuit of the switching element Q, the organic EL element EL1, the inductance L, and the capacitor C. In the off state, current flows through the inductance L, the capacitor C, the parasitic diode of the switching element Q2, and the closed circuit of the organic EL element EL1. Therefore, the direct-current voltage V0 / 2 is applied to the organic EL element EL1 and the capacitor C.

  In addition, a current flows through the closed circuit of the capacitor C, the organic EL element EL2, and the diode D, and the DC voltage V0 / 2 is also applied to the organic EL element EL2. Here, the forward voltage of the diode D is lower than V0 / 2 and can be ignored. Therefore, the drive voltage VD is supplied to the organic EL elements EL1 and EL2 by outputting a DC voltage that is double the drive voltage VD of the organic EL elements EL1 and EL2 to the output terminal of the DC power supply means 2, respectively. .

  Here, when the power switch SW of the AC power supply PS is turned off, the switching element Q of the drive voltage supply means 3 is turned off, and the switching elements Q1 and Q2 of the reverse voltage supply means 5 are turned on. Then, a reverse voltage is applied to the organic EL element EL1 by the discharge of the capacitor C in the closed circuit of the capacitor C, the inductance L, the organic EL element EL1, and the switching element Q1, and the output terminal of the DC power source means 2, the switching element Q2, and the organic EL element A reverse voltage is applied to the organic EL element EL2 by the closed circuit of the EL2 and the capacitor C by discharging the capacitor at the output end of the DC power supply means 2. The above operation waveforms are shown in FIG. Since the application time of the reverse voltage depends on the capacitance of the capacitor C, the capacitor at the output end of the DC power supply means 2, etc., the optimum time can be selected by design.

  As described above, even when the two organic EL elements EL1 and EL2 are used, the same effect as in the first embodiment can be obtained.

  By the way, as shown in FIG. 4, it is conceivable to arrange the switching element Q of the drive voltage supply means 3 and the switching element Q2 of the reverse voltage supply means 5 on the ground side. In this case, the switching element Q can be easily switched on / off, and the switching element Q2 can be easily turned on when the AC power supply PS is turned off.

(Embodiment 3)
Hereinafter, a third embodiment of the present invention will be described with reference to the drawings. In addition, about the site | part which is common in Embodiment 1, a common number is attached | subjected and description is abbreviate | omitted. In the present embodiment, two switches S1 and S2 are provided as the reverse voltage supply means 5 between the drive voltage supply means 3 and the organic EL element EL1 (see FIG. 5A). The switch S1 switches the contact between the terminal T1 connected to one end of the organic EL element EL1 and the terminal R1 on the power supply side and the terminal R2 on the ground side of the driving voltage supply means 3, and the switch S2 is an organic EL element. The contact between the terminal T2 connected to the other end of EL1, the ground side terminal R3 and the power source side terminal R4 of the drive voltage supply means 3 is switched.

  The operation of this embodiment will be described below. When the power switch SW of the AC power supply PS is on, the switch S1 connects the terminals R1 and T1, the switch S2 connects the terminals R3 and T2, and the drive voltage VD is applied to the organic EL element EL1. Is done. When the power switch SW is turned off, the switch S1 connects the terminals R2 and T1, and the switch S2 connects the terminals R4 and T2, whereby a reverse voltage is applied to the organic EL element EL1. The above operation waveform diagram is shown in FIG.

  By configuring as described above, the reverse voltage can be applied to the organic EL element EL1 only by using the two switches S1 and S2 as the reverse voltage supply means 5, so that the circuit configuration can be simplified.

It is a figure which shows 1st embodiment of the illuminating device of this invention, (a) is a whole circuit diagram, (b) is an operation | movement waveform diagram. FIG. 2 is an example of a step-down converter circuit used in the DC power supply means of the present invention, where (a) is a step-down chopper circuit, (b) is a forward converter circuit, and (c) is a flyback converter circuit. It is a figure which shows 2nd embodiment of the illuminating device of this invention, (a) is a circuit diagram, (b) is an operation | movement waveform diagram. It is a circuit diagram which shows the case where arrangement | positioning of a switching element same as the above is changed. It is a figure which shows 3rd embodiment of the illuminating device of this invention, (a) is a whole circuit diagram, (b) is an operation | movement waveform diagram. It is a circuit diagram which shows the illuminating device using the conventional organic EL element.

Explanation of symbols

EL1, EL2 Organic EL element 2 DC power supply means 3 Drive voltage supply means 4 Detection means 5 Reverse voltage supply means

Claims (5)

  A lighting device that supplies a drive voltage to one or more organic EL elements, a DC power supply that outputs a desired DC voltage, and a drive voltage that receives the output of the DC power supply and supplies a drive voltage to the organic EL elements Supply means, detection means for detecting the stop of voltage supply of the DC power supply means, and reverse voltage supply means for supplying a reverse polarity voltage to the organic EL element when the voltage supply of the DC power supply means is stopped A lighting device characterized by.   The reverse voltage supply means supplies a voltage having a reverse polarity to the organic EL element using a residual charge of a capacitor provided at an output terminal of the DC power supply means when the voltage supply of the DC power supply means is stopped. The lighting device according to claim 1.   The drive voltage supply means connects a series circuit of a switching element, a first organic EL element, an inductance and a capacitor to the output terminal of the DC power supply means, and a series circuit of a second organic EL element and a diode in parallel with the capacitor. The reverse voltage supply means is composed of first and second switching elements, and the first switching element is connected between the switching element of the drive voltage supply means and the ground side terminal of the DC power supply means. The second switching element is connected between the connection point between the second organic EL element and the diode of the drive voltage supply means and the power supply side terminal of the DC power supply means, and is the switching element of the drive voltage supply means. The lighting device according to claim 1 or 2, characterized in that is connected to the power supply side of the DC power supply means.   The drive voltage supply means connects a series circuit of a switching element, a first organic EL element, an inductance and a capacitor to the output terminal of the DC power supply means, and a series circuit of a second organic EL element and a diode in parallel with the capacitor. The reverse voltage supply means is composed of first and second switching elements, and the first switching element is connected between the switching element of the drive voltage supply means and the power supply side terminal of the DC power supply means. The second switching element is connected between the connection point between the second organic EL element and the diode of the driving voltage supply means and the ground side terminal of the DC power supply means, and the switching element of the driving voltage supply means The lighting device according to claim 1 or 2, characterized in that is connected to the ground side of the DC power supply means.   An illumination device comprising the lighting device according to claim 1 and one or more organic EL elements.

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