JP2007122979A - Lighting device and illumination device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device and an illumination device capable of easily supplying a voltage suitable for driving an organic EL element. <P>SOLUTION: The illumination device is composed of a light emitting part 1 composed of one or a plurality of organic EL elements 1a, and the lighting device supplying electric power to the light emitting part 1. Since the lighting device is provided with a direct current converting means 2 connected to an alternate current electric source to convert an alternate current voltage of a higher effective value than that of a driving voltage of the organic EL element 1a in the light emitting part 1 to a desired direct current voltage, and to output it; a polarity reversing means 3 to alternately apply the direct current voltage of the same polarity or reverse polarity of the direct current converting means 2 to the light emitting part 1; and a control means 4 to control the direct current converting means 2 so as to output nearly the same direct current voltage as the driving voltage of the organic EL element 1a in the light emitting part 1; the voltage suitable for driving the organic EL element 10 can be supplied easily. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lighting device and an illumination device that supply electric power to an organic EL element serving 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 conventional mainstream light source. Application to thin and lightweight lighting fixtures can be expected. Examples of conventional lighting devices using organic EL elements include those described in Patent Documents 1 and 2.

As shown in FIG. 4, 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, by controlling the on-duty ratio variably in the control means 40, a desired luminance can be obtained.
JP-A-2005-78828 Japanese Patent No. 2663648

  However, in the above conventional example, the converter means 20 is constituted by the diode bridge DB and the smoothing capacitor C0, and is necessary for the organic EL element 10 driven at a low voltage only by rectifying and smoothing the output of the AC power supply PS. The above voltage was supplied. Further, in Patent Document 1, since a plurality of organic EL elements 10 are connected in series so that the drive power supply voltage can be divided and driven even when the drive power supply voltage is high, for example, a commercial power supply can be used without voltage conversion as it is. However, in this case, since the applied voltage per organic EL element varies depending on the number of organic EL elements 10, it is difficult to supply a voltage suitable for driving the organic EL element 10. there were. Furthermore, since the number of organic EL elements 10 that can be used is determined by the drive power supply voltage, the number of organic EL elements 10 cannot be arbitrarily changed, and thus the amount of emitted light cannot be changed. there were.

  The present invention has been made in view of the above points, and an object thereof is to provide a lighting device and a lighting device that can easily supply a voltage suitable for driving an organic EL element.

  In order to achieve the above object, a first aspect of the present invention is a lighting device for supplying power to a light emitting unit composed of one or more organic EL elements, wherein the lighting device is connected to an AC power source and DC conversion means that converts an AC voltage having an effective value higher than the drive voltage into a desired DC voltage and outputs it, and polarity reversal that alternately applies a DC voltage of the same polarity and opposite polarity to the output of the DC conversion means And a control means for controlling the direct current conversion means so as to output a direct current voltage substantially equal to the drive voltage of the organic EL element in the light emitting section.

  According to a second aspect of the present invention, in the first aspect of the invention, the polarity inversion means connects two series circuits in which two switching elements for opening and closing the circuit connection are connected in series to the output terminal of the DC conversion means in parallel. Both ends of the light emitting part are connected between the switching elements in each series circuit.

  The invention of claim 3 is characterized by comprising the lighting device of claim 1 or 2 and a light emitting section.

  According to a fourth aspect of the present invention, in the third aspect of the present invention, the light emitting section is formed by connecting a plurality of series circuits each having an organic EL element and an inductance connected in series.

  The invention of claim 5 is characterized in that, in the invention of claim 3 or 4, the light emitting section comprises one or a plurality of sets in which a pair of organic EL elements are connected in parallel in opposite directions. To do.

  According to the first aspect of the present invention, the polarity inversion means for alternately applying the DC voltage having the same polarity and the opposite polarity to the output of the DC conversion means to the light emitting section, and the DC voltage substantially equal to the driving voltage of the organic EL element in the light emitting section. Since the control means for controlling the direct current conversion means so as to output is provided, the drive voltage of the organic EL element can be easily supplied. In addition, since a driving voltage can be individually supplied to each organic EL element regardless of the number of organic EL elements, any number of organic EL elements can be used and the light emission amount of the light emitting unit can be adjusted. . Furthermore, the lifetime of the organic EL element can be extended by alternately applying a drive voltage and a reverse polarity voltage.

  According to the invention of claim 2, the polarity inversion means comprises two series circuits in which two switching elements for opening and closing the circuit connection are connected in series and connected in parallel to the output terminal of the DC conversion means. Since both ends of the light emitting unit are connected between the switching elements in the circuit, it is possible to easily apply the drive voltage and the reverse voltage to the organic EL element.

  According to the invention of claim 3, since electric power is supplied to the light emitting section using the lighting device according to claim 1 or 2, an illuminating device capable of obtaining the effect of the invention of claim 1 or 2 can be realized.

  According to the invention of claim 4, since the light emitting section is formed by connecting a plurality of series circuits in which the organic EL element and the inductance are connected in series, the inrush generated when the polarity of the voltage applied to the light emitting section is reversed. The current can be suppressed and deterioration of the organic EL element can be prevented.

  According to the invention of claim 5, the light emitting section includes one or a plurality of sets in which a pair of organic EL elements are connected in parallel in opposite directions to each other, so that a drive voltage and a reverse voltage are alternately applied. In this case, since one of the pair of organic EL elements is always lit, the voltage use efficiency can be increased.

(Embodiment 1)
Hereinafter, a first embodiment of the present invention will be described with reference to FIG. As shown in FIG. 1, the present embodiment is a lighting device that includes a light emitting unit 1 including one or more organic EL elements 1 a and a lighting device that supplies power to the light emitting unit 1. DC conversion means 2 that is connected to a power source and converts an AC voltage having an effective value higher than the drive voltage of the organic EL element 1a in the light emitting section 1 to a desired DC voltage, and has the same polarity as the output of the DC conversion means 2 And polarity inversion means 3 for alternately applying a DC voltage of opposite polarity to the light emitting section 1 and control for controlling the DC conversion means 2 so as to output a DC voltage substantially equal to the drive voltage of the organic EL element 1a in the light emitting section 1. Means 4 are provided.

  The organic EL element 1 a of the light emitting unit 1 emits light when a DC voltage is applied in a specified direction, and is driven by a DC voltage output from the DC conversion means 2 here. The light emitting unit 1 of the present embodiment is configured with one organic EL element 1a (see FIG. 1A) and when configured with a pair of organic EL elements 1a connected in parallel (FIG. 1 ( b))), and the latter organic EL element 1a is configured to be opposite to each other. In addition, the number of the organic EL elements 1a of the light emitting unit 1 is not limited to one or two, but a plurality of sets of a pair of organic EL elements 1a connected in parallel in opposite directions. It may be configured.

  The DC conversion means 2 is composed of a rectifier circuit 2a and a step-down converter circuit 2b, and full-wave rectifies an AC voltage from an AC power source using a rectifier circuit 2a composed of a diode bridge, and a rectified pulsating voltage is obtained. The voltage is stepped down to a predetermined DC voltage using the step-down converter circuit 2b. The step-down converter circuit 2b controls the switching element Q such as a MOSFET by the control means 4 to change the on-duty ratio of the switching element, that is, performs a PWM control to generate a DC voltage of a desired magnitude in the organic light emitting unit 1 In this embodiment, the control means 4 always outputs a voltage (driving voltage) V0 necessary to drive one organic EL element 1a of the light emitting unit 1 in this embodiment. PWM control is performed. Since the diode bridge of the rectifier circuit 2a, the circuit configuration of the step-down converter circuit 2b, and the PWM control by the control means 4 are well known, detailed description thereof is omitted here.

  The polarity reversing means 3 is composed of switching elements 3a to 3d such as MOSFETs, and the switching elements 3a and 3b connected in series and the switching elements 3c and 3d connected in series are connected in parallel. Are connected to the output terminal of the step-down converter circuit 2b. The light emitting unit 1 is connected between the connection point of the switching elements 3a and 3b and the connection point of the switching elements 3c and 3d, and the output voltage V0 of the step-down converter circuit 2b is applied. The switching elements 3a to 3d can be turned on / off by a control signal from an inversion control means (not shown) for controlling them, and the switching elements 3a to 3d are turned on / off to emit light. A forward voltage V0 and a reverse voltage V0 are alternately applied to the unit 1.

  Specifically, a pulse as shown in the upper part of FIG. 1C is supplied from the inversion control means to the switching elements 3a and 3d, and at the same time, a pulse as shown in the lower part of FIG. 1C is supplied to the switching elements 3b and 3c. By supplying, the switching elements 3a and 3d and the switching elements 3b and 3c are alternately turned on / off. The on-time of the switching elements 3a and 3d is substantially equal to the on-time of the switching elements 3b and 3c. When the light emitting unit 1 is composed of one organic EL element 1a (see FIG. 1A), the forward voltage V0 is applied to the organic EL element 1a when the switching elements 3a and 3d are on, and 3b and 3c are off. When the switching elements 3a and 3d are turned off and the switching elements 3b and 3c are turned on, a reverse voltage V0 is applied to the organic EL element 1a and the light is turned off (see FIG. 1C). .

  In addition, when the light emitting unit 1 is configured by connecting a pair of organic EL elements 1a in parallel (see FIG. 1B), the upper side in the figure when the switching elements 3a and 3d are on, and 3b and 3c are off. A forward voltage V0 is applied to the organic EL element 1a to emit light, and a reverse voltage V0 is applied to the lower organic EL element 1a to turn off the light. When the switching elements 3a and 3d are turned off, and 3b and 3c are turned on, a reverse voltage V0 is applied to the upper organic EL element 1a and the light is extinguished, and a forward direction is applied to the lower organic EL element 1a. The voltage V0 is applied to emit light.

  By the way, since the organic EL element 1a includes a parallel plate capacitor structure due to its structure, the capacitor is electrically connected in parallel with the diode. For this reason, when switching the organic EL element 1a, if the switching frequency is increased, the polarity is reversed before the capacity of the organic EL element 1a is charged, and the discharge is started and sufficient light emission does not occur. sell. Therefore, considering the capacity of the organic EL element 1a, the switching frequency is preferably about several kHz or less. If the switching frequency is too low, blinking of the organic EL element 1a is noticeable, so at least twice the frequency (50 Hz or 60 Hz) of the commercial power supply, more preferably several hundred Hz or more is desirable.

  As described above, since the step-down converter circuit 2b (DC conversion means 2) always outputs the drive voltage V0 of the organic EL element 1a, the drive voltage is applied to each organic EL element 1a regardless of the number of organic EL elements 1a. V0 can be supplied. Therefore, the light emission amount of the light emitting unit 1 can be changed by arbitrarily changing the number of the organic EL elements 1a. Moreover, it is known that the lifetime of the organic EL element 1a is extended by applying a voltage having a polarity opposite to the driving voltage of the organic EL element 1a (see Patent Document 2). In this embodiment, the organic EL element 1a is applied to the organic EL element 1a. Since the forward voltage V0 and the reverse voltage V0 are alternately applied, the lifetime of the organic EL element 1a can be extended. Furthermore, when the light emitting unit 1 is configured by connecting a pair of organic EL elements 1a in parallel in opposite directions, any one of the organic EL elements 1a always emits light, so that the applied voltage can be used efficiently. Can do.

(Embodiment 2)
Hereinafter, a second embodiment of the present invention will be described with reference to FIG. Since the basic configuration of the present embodiment is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  When the forward voltage V0 and the reverse voltage V0 are alternately applied to the organic EL element 1a, the polarity of the applied voltage is reversed in parallel with the organic EL element 1a as shown in the upper part of FIG. In this case, the inrush current flows due to the presence of the capacitor, and the organic EL element 1a may be deteriorated. Therefore, in the present embodiment, as shown in FIG. 2A, a plurality of organic EL elements 1a are connected in parallel to form a light emitting unit 1, and an inductance 1b is connected in series to each organic EL element 1a. Yes.

  As described above, since the inductance 1b is connected in series to each organic EL element 1a, as shown in FIG. 2 (c), the inrush current generated when the polarity of the applied voltage is reversed is suppressed by the inductance 1b, and the organic EL element 1a. Can be prevented. In addition, since the inductance 1b is connected to each organic EL element 1a, the inductance 1b can be reduced as compared with the case where one inductance 1b is used for all the organic EL elements 1a. As shown in FIG. 2 (b), the light emitting unit 1 includes a pair of a pair of organic EL elements 1a connected in parallel in opposite directions and an inductance 1b connected in series with each organic EL element 1a. A plurality of sets may be connected in parallel.

(Embodiment 3)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. Since the basic configuration of the present embodiment is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, two capacitors C1 and C2 are connected in series to the output terminal of the step-down converter circuit 2b so that the step-down converter circuit 2b outputs a voltage 2V0 that is twice the drive voltage V0 of the organic EL element 1a. It is controlled by the control means 4. The polarity inversion means 3 is formed by connecting two switching elements 3a and 3b in series, and is connected in parallel with the series circuit of capacitors C1 and C2 of the step-down converter circuit 2b. The light emitting unit 1 is formed by connecting a pair of organic EL elements 1a in parallel in opposite directions and an inductance 1b in series, sandwiched between capacitors C1 and C2, and switching elements 3a and 3b. It is connected between the sandwiched points.

  The inversion control means of the polarity inversion means 3 controls the switching elements 3a and 3b to be alternately turned on / off, and the on-time of each is substantially equal. Therefore, when the switching element 3a is on and 3b is off, the voltage V0 output to the capacitor C1 is applied to the light emitting unit 1, and the reverse voltage V0 is applied to the upper organic EL element 1a in FIG. A forward voltage V0 is applied to the lower organic EL element 1a. When the switching element 3a is turned off and 3b is turned on, the voltage V0 output to the capacitor C2 is applied to the light emitting unit 1, and the forward voltage V0 is applied to the upper organic EL element 1a to reduce the lower voltage. A reverse voltage V0 is applied to the organic EL element 1a on the side.

  By configuring as described above, the forward voltage V0 and the reverse voltage V0 can be alternately applied to the organic EL element 1a even in the on / off control of the two switching elements 3a and 3b. The circuit configuration of the inverting means 3 can be simplified, and switching control is facilitated. Further, since the inductance 1b is connected in series to the pair of organic EL elements 1a, an inrush current at the time of voltage polarity reversal can be suppressed.

(Embodiment 4)
Hereinafter, a third embodiment of the present invention will be described with reference to FIG. Since the basic configuration of the present embodiment is the same as that of the first embodiment, the same components are denoted by the same reference numerals and description thereof is omitted.

  In the present embodiment, the step-down converter circuit 2b is controlled by the control means 4 so as to output a voltage 2V0 that is twice the drive voltage V0 of the organic EL element 1a, and the polarity inversion means is provided at the output end of the step-down converter circuit 2b. 3, a switching element 3a, 3b connected in series is connected, and a series circuit of the light emitting unit 1 and the capacitor C3 is connected in parallel to the switching element 3b. The light emitting unit 1 is formed by connecting a pair of organic EL elements 1a connected in parallel in opposite directions and an inductance 1b in series.

  The inversion control means of the polarity inversion means 3 controls the switching elements 3a and 3b to be alternately turned on / off, and the on-time of each is substantially equal. Therefore, when the voltage V0 is output to the capacitor C3 and the switching element 3a is on and 3b is off, the forward voltage V0 is applied to the upper organic EL element 1a in FIG. A reverse voltage V0 is applied to the EL element 1a. When the switching element 3a is turned off and 3b is turned on, the voltage V0 output to the capacitor C3 is applied to the light-emitting portion 1, and the reverse voltage V0 is applied to the upper organic EL element 1a. A forward voltage V0 is applied to the organic EL element 1a on the side.

  By configuring as described above, the forward voltage V0 and the reverse voltage V0 can be alternately applied to the organic EL element 1a even in the on / off control of the two switching elements 3a and 3b. The circuit configuration of the inverting means 3 can be simplified, and switching control is facilitated. Further, since the inductance 1b is connected in series to the pair of organic EL elements 1a, an inrush current at the time of voltage polarity reversal can be suppressed.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure which shows the illuminating device of 1st embodiment of this invention, (a) is a circuit diagram which shows the case where there is one organic EL element, (b) is connecting a pair of organic EL element in the opposite direction in parallel (C) is a waveform diagram showing the relationship between the switching operation of the polarity inversion means and the voltage applied to the organic EL element. It is a figure which shows the illuminating device of 2nd embodiment of this invention, (a) is a circuit diagram at the time of connecting all the organic EL elements in parallel in the same direction, (b) is a pair of organic EL element reverse each other It is a circuit diagram at the time of connecting two or more sets in parallel in the direction, (c) is an explanatory view showing the effect of inductance. It is a circuit diagram which shows the illuminating device of 3rd embodiment of this invention. It is a circuit diagram which shows the illuminating device of 4th embodiment of this invention. It is a circuit diagram which shows the illuminating device using the conventional organic EL element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light emission part 1a Organic EL element 1b Inductance 2 DC conversion means 2a Rectifier circuit 2b Step-down converter circuit 3 Polarity inversion means 3a-3d Switching element 4 Control means

Claims (5)

  A lighting device that supplies power to a light emitting unit composed of one or a plurality of organic EL elements, and is connected to an AC power source and applies an AC voltage having a higher effective value than a driving voltage of the organic EL elements in the light emitting unit to a desired DC voltage DC conversion means for converting to and outputting, polarity inversion means for alternately applying a DC voltage of the same polarity and opposite polarity to the output of the DC conversion means, and the drive voltage of the organic EL element in the light emission section are substantially equal A lighting device comprising: control means for controlling the direct current conversion means so as to output a direct current voltage.   The polarity reversing means comprises two series circuits in which two switching elements for opening and closing the circuit connection are connected in series and connected in parallel to the output terminal of the DC conversion means, and a light emitting section between the switching elements in each series circuit The lighting device according to claim 1, wherein both ends thereof are connected.   An illumination device comprising the lighting device according to claim 1 and the light emitting unit.   The lighting device according to claim 3, wherein the light emitting unit is formed by connecting a plurality of series circuits each having an organic EL element and an inductance connected in series. 5. The lighting device according to claim 3, wherein the light-emitting unit includes one or a plurality of sets each including a pair of organic EL elements connected in parallel in opposite directions.

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