JP2014165104A - Organic EL lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an organic EL lighting device in which luminance unevenness and luminance reduction that progress in light-out due to electric charge remaining (residual electric charge) in an electrode are less likely to occur.SOLUTION: An organic EL lighting device 1 comprises: power supply means 2 supplying a power for lighting an organic EL element (EL); and power supply switch means 3 turning on/off the power to be supplied from the power supply means 2 to the organic EL element (EL). Electric charge stored in an electrode of the organic EL element (EL) at the lighting when the power supply switch means 3 is turned on is removed or reduced at the light-out when the power supply switch means 3 is turned off. In concrete terms, a configuration having a parallel resistor 4 connected in parallel to the organic EL element (EL) can be achieved.

Description

  The present invention relates to an organic EL lighting device for lighting an organic EL element.

  The phenomenon of emitting light of a wavelength corresponding to the electronic band structure when an electric field is applied to a substance is called electroluminescence. A light-emitting element utilizing this phenomenon is an electroluminescence light-emitting element (hereinafter referred to as an EL element).

  As this EL element, there is a so-called organic EL element using an organic substance as a light emitting material in addition to a so-called inorganic EL element using an inorganic substance as a light emitting material. In this organic EL element, a light-emitting layer containing an organic light-emitting material such as Alq3 or PPV is provided between a pair of opposed electrodes, holes and electrons are injected into the light-emitting layer from each of the pair of electrodes, and the light-emitting layer is regenerated inside the light-emitting layer. It is an element that emits light having a wavelength corresponding to the HOMO-LUMO gap of the organic light emitting material by generating excitons by combining them.

  Organic EL elements are likely to play a role in future indoor lighting as thin surface light sources, and each company is working to increase efficiency and output. In addition, when the purpose of illumination is taken into consideration, an increase in area is also required. The basic structure of organic EL is, for example, a structure in which an anode (transparent electrode), a hole injection layer, a hole transport layer, a light emitting layer, an electron transport layer, an electron injection layer, and a cathode (metal electrode) are laminated on a glass substrate. There is. When a DC voltage is applied between the cathode and the anode, ions and electrons recombine in the light emitting layer, and the recombination energy at that time is emitted as light. Briefly, it has a structure in which an organic thin film is sandwiched between an anode and a cathode, and emits light by applying a DC voltage.

  One of the problems with organic EL devices is reliability. That is, when the organic EL element is lit for a long time, a phenomenon that it becomes inconspicuous or extreme luminance unevenness / luminance reduction occurs occurs.

  In order to solve this problem, various techniques have been proposed, and many of them relate to organic thin film materials and film forming processes. For example, in Patent Document 1 below, attention is paid to the film formation conditions, and, “Before film formation, the atmosphere for forming the organic thin film layer is adjusted to an atmosphere containing a low dew point and containing organic vapor, and the organic thin film is formed in the atmosphere. Organic thin film layer forming method of organic EL element, characterized in that a layer is formed. "By this," a high-reliability polymer organic EL element in which dark spots are less likely to occur with time " Can provide a method for forming an organic thin film layer, etc. ”.

JP2007-273229A

  As described above, when the organic EL element is lit for a long time, a phenomenon occurs in which it becomes inconspicuous or extreme luminance unevenness or luminance decreases. These phenomena are greatly influenced by the lighting time, but are also influenced by the lighting time. That is, if the light is turned off for a long time and then turned on again, there will be a phenomenon in which it becomes inconspicuous or extreme luminance unevenness or luminance decreases. This is because the charge (residual charge) accumulated on the electrodes causes an attractive force between the electrodes even during extinction, causing a short-circuit phenomenon partially, and the force acting on the dielectric interface varies depending on the location. This is because the contact density varies depending on the location.

  If electric charges exist in the electrodes, a force acts between the electrodes and the dielectric interface. Although this force is unavoidable during lighting, if there is a charge on the electrode even during extinguishing, this force always exists even when the electrode is not lit, and it tends to cause uneven brightness and inconvenience. This significantly reduces the reliability related to the lifetime of the organic EL element. Therefore, when the light is extinguished, it is necessary to eliminate the residual charge. An object of the present invention is to eliminate the cause of output decrease that occurs when the light is turned off.

  That is, an object of the present invention is to propose an organic EL lighting device that is less likely to cause uneven brightness and lowering of brightness when the light is extinguished by the charge remaining on the electrode (residual charge).

Hereinafter, the above phenomenon will be described in detail. The organic thin film used for the organic EL element has low electrical conductivity and can be regarded as having a property as a dielectric. For this reason, it is necessary to make the thickness of the organic thin film very thin (for example, about several tens of nm) in order to increase the efficiency. Therefore, even if the applied voltage is several volts, the electric field strength is on the order of 10 ⁸ V / m, which is very strong. As shown in FIG. 6, an attractive force acts between the parallel plate electrodes, and the magnitude of the force per unit area is expressed by Equation (1).
Here, F is the magnitude of the force [N], ε is the dielectric constant of the dielectric, and E is the electric field strength between the electrodes.

When two types of dielectrics exist between the capacitors, a force acts not only on the electrodes but also on the dielectric interface as shown in FIG. F ₁ , F ₂ , and F _{3 in} FIG. 7 can be expressed by Expression (2).
Here, FIG. 7 shows the direction of force when ε ₂ > ε ₁ .

Moreover, since the organic EL element has a large area of the light emitting portion (usually several cm square to 10 cm square or more), there are the following problems in manufacturing.
(A) It is difficult to make the thickness of the dielectric film uniform, and the thickness tends to be non-uniform.
(B) Since the transparent conductive film has a resistance value and it is difficult to control the value, a voltage drop occurs on the anode surface, and the electric field strength in the dielectric varies depending on the location.

  By design, the organic EL element has only one light emitting layer (thin dielectric layer is thin and the voltage between terminals is low), and several types of light emitting layers are connected in series (dielectric) The layer is thicker and the voltage across the terminals is relatively high).

  First, what kind of problems occur with respect to the above-mentioned (A) and (B) for the type having only one light emitting layer (the dielectric layer is thin and the voltage between terminals is low)? I'll think about it.

Let's consider what kind of trouble exists in the case of (A). FIG. 8 shows a schematic diagram of the representative case. Since a constant voltage is applied to the electrode, both the electric field strength and the electric flux density in the place where the thickness is thin (region [2] in FIG. 8) are the surroundings (region [1] in FIG. 8). Get higher. Therefore, the force acting on the region [2] (F _{2 in} FIG. 8) is larger than the force acting on the region [1] (F _{1 in} FIG. 8). Therefore, a force for further shortening the distance between the electrodes acts in the region [2]. At the same time, the region [2] dielectric has a tendency to spread in the region [1] at the boundary surface of the region, so that the density of the portion tends to be reduced. It will approach. As a result, the portion is in a state close to a short circuit, no current flows through the entire surface, and no light is emitted. Or it leads to the phenomenon that only one part emits light.

Consider the case of (B). A conceptual diagram of this case is shown in FIG. Since the transparent conductive film used for the anode has resistance, a voltage drop on the anode surface occurs as the distance from the feeding point from the electrode increases. Therefore, the electric field strength and electric flux density near the feeding point (region [2]) are larger than those at a distant location (region [1]). The forces F ₁ and F ₂ acting between the electrodes in the region [2] and the region [1] are expressed by Expression (3).
Here, F ₂ > F ₁ is satisfied from E ₂ > E ₁ . Therefore, a force for further shortening the distance between the electrodes acts in the region [2]. At the same time, the region [2] dielectric has a tendency to spread in the region [1] at the boundary surface of the region, so that the density of the portion tends to be reduced. It will approach. As a result, the portion is in a state close to a short circuit, no current flows through the entire surface, and no light is emitted. Or it leads to the phenomenon that only one part emits light.

  Here, considering the case where there is no variation in the surface resistance of the transparent conductive film, a comparison was made between the vicinity of the feeding point and a location away from it, but if there is a variation in the surface resistance, it is a place that is at the same distance from the feeding point. It is easy to understand that the same phenomenon occurs. When the organic EL that has been allowed to stand for a long time after being lit is lit, or when the organic EL is lit for a long time, the luminance may decrease and luminance unevenness may occur in both cases.

  Next, with respect to the types (A) and (B) described above, some types of light emitting layers are connected in series (the dielectric layer is thick and the voltage between terminals is relatively high). Consider what kind of problems will occur. In this case, the force applied between the electrodes is basically the same as that having only one light emitting layer (the dielectric layer is thin and the voltage between terminals is low), but the dielectric layer is thick. Therefore, a short circuit between the electrodes does not occur. However, as shown in FIG. 7, due to the force applied to the dielectric interface, the density of the dielectric changes with time, causing a change (increase or decrease) in the terminal voltage. In addition, when the force applied to the dielectric interface varies from place to place, the contact density at the interface changes from place to place, causing uneven brightness.

  In order to solve the above-mentioned problem, the power supply means for supplying power for lighting the organic EL element, and the power supply switch means for turning ON / OFF the power supplied from the power supply means to the organic EL element, The organic EL lighting device is configured such that the charge accumulated in the electrode of the organic EL element at the time of lighting with the power switch means turned on is removed or reduced when the power switch means is turned off when the power switch means is turned off. When the power switch means is turned on, a forward voltage is applied to the organic EL element to emit light.

  Specifically, by providing a parallel resistor connected in parallel to the organic EL element, the charge accumulated in the electrode of the organic EL element is removed or reduced when the power switch unit is turned off. An organic EL lighting device can be obtained.

  At this time, it is connected in series to the parallel resistance, and includes parallel resistance switch means for turning on / off the connection between the organic EL element and the parallel resistance. When the power switch means is turned on, the parallel resistance switch means While being turned off, the parallel connection between the organic EL element and the parallel resistor is released. On the other hand, when the power switch means is turned off, the parallel resistance switch means is turned on so that the organic EL element and the parallel resistance are in parallel. It is preferable that the organic EL lighting device is configured such that the charges accumulated in the electrodes of the organic EL element are removed or reduced by being connected.

  Further, when the power switch means is turned off, the polarity of the power supplied from the power supply means to the organic EL element is reversed for a predetermined time so that the charge accumulated in the electrodes of the organic EL element is removed or reduced. It can also be set as the comprised organic EL lighting device.

  Moreover, it is an organic EL lighting device for lighting two organic EL elements, and when the power switch means is turned on, the two organic EL elements are connected in parallel, and the power switch means is turned off. Sometimes, by short-circuiting the positive electrode side of one organic EL element and the negative electrode side of the other organic EL element, the negative electrode side of one organic EL element and the positive electrode side of the other organic EL element are short-circuited. It can also be set as the organic EL lighting device comprised so that the electric charge accumulate | stored in the electrode of EL element might be removed or reduced.

  According to the present invention, it is possible to propose an organic EL lighting device that is less likely to cause uneven luminance and lowering of brightness when the light is extinguished by the charge remaining on the electrode (residual charge).

It is a figure which illustrates the organic electroluminescent lighting device of 1st embodiment. It is a figure which illustrates the organic electroluminescent lighting device of 2nd embodiment. It is a figure which illustrates the organic electroluminescent lighting device of 3rd embodiment. It is a figure which shows the change of the electric charge (residual electric charge) of an electrode. It is a figure which illustrates the organic electroluminescent lighting device of 4th embodiment. It is principle explanatory drawing of the force which acts on the electrode of a capacitor | condenser. It is explanatory drawing of the force concerning each part of the capacitor which has two types of dielectrics. It is principle explanatory drawing which shows the force which acts between electrodes when the distance between electrodes is not uniform. It is principle explanatory drawing which shows the force which acts between electrodes when an electrode has resistance value.

  Hereinafter, an organic EL lighting device will be described as an example. The organic EL lighting device includes a power supply means and a power switch means, and the charge accumulated in the electrode of the organic EL element at the time of lighting when the power switch means is turned on is removed or reduced when the power switch means is turned off. It is comprised so that.

1. First Embodiment As shown in FIG. 1, the organic EL lighting device 1 of the present embodiment includes a parallel resistor 4 connected in parallel to an organic EL element (EL) in addition to the power supply means 2 and the power switch means 3. Thus, the charge accumulated in the electrode of the organic EL element (EL) is naturally removed or reduced after the power switch means 3 is turned off. Hereinafter, each component will be described in detail.

[Power supply means]
The power supply means 2 supplies power for lighting the organic EL element (EL), which is a light emitting source, to the organic EL element (EL). Usually, a lighting circuit or the like is built in, and power corresponding to an organic EL element (EL) to be used is supplied. There are various configurations of organic EL elements (EL) used as a light emitting source, and new configurations have been studied, but are not particularly limited. Since the organic EL element (EL) is normally DC driven, a DC power source is used as the power supply means 2 and power is supplied to the organic EL element (EL) in the forward direction.

[Power switch means]
The power switch means 3 is for turning on / off the power supplied from the power means 2 to the organic EL element (EL). In FIG. 1, the power switch means 3 is provided in the wiring path which conducts the positive electrode side of the power supply means 2 and the positive electrode side of the organic EL element. Various switches can be used as the power switch means 3.

[Parallel resistance]
As shown in FIG. 1, the parallel resistor 4 is connected in parallel to an organic EL element (EL). The resistance value of the parallel resistor 4 is not particularly limited, but is preferably 10 kΩ to 1 MΩ, and more preferably 50 kΩ to 300 kΩ.

  The parallel resistance 4 removes or reduces charges accumulated in the electrodes of the organic EL element (accumulated when the power switch means 3 is turned on) when the power switch means 3 is turned off. FIG. 1 shows a state when the power switch means 3 is turned off and is extinguished.

In the organic EL lighting device 1 of the first embodiment, power loss due to the parallel resistance 4 occurs during lighting. Its magnitude is inversely proportional to the resistance value of the parallel resistor 4 and proportional to the square of the voltage applied to the organic EL element (EL). For example, if the applied voltage is about 5 V at the maximum and the resistance value of the parallel resistor 4 is 100 kΩ, the power consumption is about 0.25 mW. Considering that the power consumption of the organic EL element is about 2 W, it seems to be acceptable in practical use.
At this time, when the distance between the electrodes is 100 nm and the relative permittivity of the dielectric is 3 in the 10 cm square organic EL element, the capacitance is as shown in the equation (4).
Since the time (time constant) required for discharging the residual charge is given by C × R, when R = 100 kΩ, it is 0.27 seconds, and the residual charge can be removed in a short time.

2. Second Embodiment In the organic EL lighting device 1 of the first embodiment described above, power loss due to the parallel resistance 4 occurs during lighting, but this is solved by the organic EL lighting device 1 of the second embodiment. . In the second embodiment, in addition to the components of the first embodiment, as shown in FIG. 2, a parallel resistance switch means 5 is provided.

[Parallel resistance switch means]
The parallel resistance switch means 5 is connected in series to the parallel resistance 4 and is used to turn on / off the connection between the organic EL element (EL) and the parallel resistance 4. Various switches can be used as the parallel resistance switch means 5. As shown in FIG. 2, when the power switch means 3 is turned on, the parallel resistance switch means 5 is turned off and the parallel connection between the organic EL element and the parallel resistance 4 is released. As a result, power loss during lighting due to the parallel resistor 4 does not occur.

  On the other hand, when the power switch means 3 is turned off, the parallel resistance switch means 5 is turned on, and the organic EL element (EL) and the parallel resistance 4 are connected in parallel, as in the first embodiment. Charges accumulated in the electrodes of the organic EL element (EL) (accumulated during lighting when the power switch means 3 is turned on) are removed or reduced.

  In this way, the parallel resistance switch means 5 may be configured to be turned off / on in conjunction with the ON / OFF of the power switch means 3, but such a configuration can be realized using various means. it can. For example, if a multi-pole (two-pole) switch is used, the configuration is simple. In addition, power switch detection means for detecting ON / OFF of the power switch means 3 is provided, and parallel resistance switch control means for turning OFF / ON the parallel resistance switch means 5 according to a detection signal from the power switch detection means is provided. May be.

2. Third Embodiment FIG. 3 shows an organic EL lighting device according to a third embodiment. In the present embodiment, when the organic EL is turned off, the power source is connected to the organic EL in the opposite direction (plus / minus is inverted), thereby erasing the charge (residual charge). Hereinafter, a specific description will be given based on FIG.

  Similar to the above-described embodiment, this embodiment also includes power supply means 2 for supplying power for lighting the organic EL element (EL) to the organic EL element.

  In this embodiment, the inversion first wiring 61 and the inversion second wiring 62 are also provided. The first inversion wiring 61 has a load resistor 7 and branches from the negative electrode side of the organic EL element (EL). When the light is extinguished, the first power switch means 31 (described later) sets the tip side y1 to the positive electrode of the power supply means 2. Connected with the side. The second inversion wiring 62 has a load resistor 7 and branches from the positive electrode side of the organic EL element (EL). When the light is extinguished, the tip side y2 is connected to the power source means 2 by the second power switch means 32 (described later). Connected to the negative electrode side.

  In the present embodiment, the first power switch means 31 and the first power switch means 31 are used as power switch means for turning ON / OFF the power supplied from the power supply means 2 to the organic EL element (EL) (forward power ON / OFF). Dual power switch means 32 is provided. Here, the first power supply switch means 31 switches the connection between the positive electrode side x1 of the organic EL element (EL) and the tip end side y1 of the inversion first wiring 61 with the positive electrode side of the power supply means 2 as a basic axis. It is. The second power switch means 32 switches the connection between the negative electrode side x2 of the organic EL element (EL) and the tip end side y2 of the inversion second wiring 62 with the negative electrode side of the power supply means 2 as a basic axis. is there.

  At the time of lighting, the first power switch means 31 is positioned on the positive electrode side x1 of the organic EL element (EL) and the second power switch means 32 is positioned on the negative electrode side x2 of the organic EL element (EL). The EL element (EL) is caused to emit light.

  On the other hand, when the light is turned off, the first power switch means 31 is positioned on the tip side y1 of the reversing first wiring 61 for a predetermined time, and the second power switch means 32 is positioned on the tip side y2 of the reversing second wiring 62 for a predetermined time. By reversing the polarity of the electric power supplied from the power supply means 2 to the organic EL element (EL) for a predetermined time (applying a reverse voltage, in detail, the voltage in the direction opposite to that when the power switch means is turned on is turned on. The charge accumulated in the electrodes of the organic EL element is removed or reduced. After the reverse voltage is applied, for example, the first power switch means 31 and the second power switch means 32 may be set in a free state.

  Here, the time τ for applying the reverse voltage (the predetermined time) is obtained as follows. It is preferable to provide control means (reverse voltage application time control means) so as to apply the reverse voltage for the time τ to control the first power switch means 31 and the second power switch means 32.

In FIG. 3, it is assumed that the charge Q ₀ [C] is stored in the electrode during lighting. From the moment when the first power switch means 31 and the second power switch means 32 are switched and turned off, the charge Q of the electrode begins to change as shown in FIG. The change is shown by Formula (5).
Here, R is the resistance value of the load resistor 7 shown in FIG. 3, and C is the capacitance of the organic EL. From this equation, the time τ for connecting the switch to the terminal 2 is obtained by equation (6).
For example, when R = 100 kΩ and C = 2.7 × 10 ⁻⁶ C, τ = 0.817 s.

2. Fourth Embodiment FIG. 5 shows an organic EL lighting device according to a fourth embodiment. This organic EL lighting device lights two organic EL elements. Charge (residual charge) is removed or reduced by using a pair of organic EL elements (EL1, EL2) that emit light by being connected in parallel when turned on and by reversely connecting the organic EL elements when turned off.

Specifically, in this embodiment, two organic EL elements are arranged in parallel at the time of lighting shown in FIG. 5A (each power switch means 35, 36, 37, 38 is in the ON position). When the light is turned off as shown in FIG. 5B (each power switch means 35, 36, 37, 38 is in the OFF position), the positive side of one organic EL element (EL1) and the other organic By short-circuiting the negative electrode side of the EL element (EL2), and short-circuiting the negative electrode side of one organic EL element (EL1) and the positive electrode side of the other organic EL element (EL2), The accumulated charge is removed or reduced.
Hereinafter, a specific description will be given based on FIG.

  Similar to the above-described embodiment, this embodiment also includes power supply means 2 for supplying power for lighting the organic EL element to the organic EL element. However, the first organic EL element (EL1) and the second organic EL element (EL2) are used as the organic EL elements to be lit. The first organic EL element (EL1) and the second organic EL element (EL2) are connected in parallel during lighting.

  In this embodiment, a short-circuit first wiring 81 and a short-circuit second wiring 82 are also provided. The first short circuit wiring 81 is for short-circuiting the positive electrode side of the first organic EL element (EL1) and the negative electrode side of the second organic EL element (EL2) when the light is extinguished. 82 is for short-circuiting the negative electrode side of the first organic EL element (EL1) and the positive electrode side of the second organic EL element (EL2) when the light is extinguished.

In the present embodiment, the first positive power supply switch means 35, the first negative power supply switch means 36, the second positive power supply switch means 37, and the second negative power supply switch means 38 are provided as the power switch means.

  Here, the first positive power supply switch means 35 is connected between the positive electrode side of the power supply means 2 and one end side of the short-circuit first wiring 81 with the positive electrode side of the first organic EL element (EL1) as a basic axis. It is to switch. The first negative power supply switch means 36 switches the connection between the negative electrode side of the power supply means 2 and one end side of the short-circuit second wiring 82 with the negative electrode side of the first organic EL element (EL1) as a basic axis. Is. The second positive power supply switch means 37 is connected between the positive electrode side of the power supply means 2 and the other end side of the short-circuit second wiring 82 with the positive electrode side of the second organic EL element (EL2) as a basic axis. It is to switch. The second negative power supply switch means 38 is connected between the negative electrode side of the power supply means 2 and the other end side of the short-circuit first wiring 81 with the negative electrode side of the second organic EL element (EL2) as a basic axis. It is to switch.

  At the time of lighting, as shown in FIG. 5 (a), the first positive power supply switch means 35 is on the positive side of the power supply means 2, the first negative power supply switch means 36 is on the negative side of the power supply means 2, and the second positive electrode The power switch means 37 is positioned on the positive side of the power supply means 2 and the second negative power supply switch means 38 is positioned on the negative side of the power supply means 2 so that the first organic EL element (EL1) and the second organic EL element ( EL2) is connected in parallel to cause both organic EL elements to emit light.

  On the other hand, when the light is turned off, as shown in FIG. 5B, the first positive power supply switch means 35 is connected to one end of the short-circuit first wiring 81 and the first negative power supply switch means 36 is connected to one end of the second short-circuit wiring 82. The second positive power switch means 37 is positioned on the other end side of the second short-circuit wiring 82 and the second negative power switch means 38 is positioned on the other end side of the first short-circuit wiring 81, While short-circuiting the positive electrode side of the organic EL element (EL1) and the negative electrode side of the second organic EL element (EL2), the negative electrode side of the first organic EL element (EL1) and the second organic EL element (EL2) In other words, the charge accumulated in the electrodes of both organic EL elements is removed or reduced. At this time, the first organic EL element (EL1) and the second organic EL element (EL2) are both disconnected from the power supply means 2 and are in an electrically independent state. The first organic EL element (EL1) and the second organic EL element (EL2) preferably have the same capacitance.

  Although the present invention has been described above with reference to specific embodiments, the present invention is not limited to the above-described embodiments, and claims attached to the application of the present application by those skilled in the art or the like. Various changes and modifications can be made without departing from the scope.

1 Organic EL lighting device

2 Power supply means 3 Power switch means
31 First power switch means
32 Second power switch means
35 First positive power switch means
36 First negative power switch means
37 Second positive power switch means
38 Second negative power switch means

4 parallel resistance 5 parallel resistance switch means

61 First wiring for reversal
62 Second wiring for inversion 7 Load resistance

81 First wiring for short circuit
82 Second wiring for short circuit


EL Organic EL device
EL1 First organic EL element
EL2 Second organic EL element

Claims (5)

Power supply means for supplying power for lighting the organic EL element;
Power supply switch means for turning ON / OFF the power supplied from the power supply means to the organic EL element,
The charge accumulated in the electrode of the organic EL element during lighting with the power switch means turned on is configured to be removed or reduced when the power switch means is turned off.
Organic EL lighting device.
By providing a parallel resistor connected in parallel to the organic EL element,
The charge accumulated in the electrode of the organic EL element is configured to be removed or reduced when the power switch means is turned off and turned off.
The organic EL lighting device according to claim 1.
A parallel resistance switch means connected in series to the parallel resistance, for turning on / off the connection between the organic EL element and the parallel resistance;
At the time of lighting with the power switch means turned on, the parallel resistance switch means is turned off, and the parallel connection between the organic EL element and the parallel resistance is released,
When the power switch means is turned off, the parallel resistance switch means is turned on and the organic EL element and the parallel resistance are connected in parallel to remove or reduce the charge accumulated in the electrodes of the organic EL element. Configured to be
The organic EL lighting device according to claim 2.
When turning off the power switch means, the polarity of the power supplied from the power means to the organic EL element is reversed for a predetermined time,
The charge accumulated in the electrode of the organic EL element is configured to be removed or reduced.
The organic EL lighting device according to claim 1.
An organic EL lighting device for lighting two organic EL elements,
When lighting with the power switch means ON, two organic EL elements are connected in parallel,
When turning off the power switch means, the positive electrode side of one organic EL element and the negative electrode side of the other organic EL element are short-circuited, and the negative electrode side of one organic EL element and the positive electrode side of the other organic EL element Are configured such that the charge accumulated in the electrodes of the organic EL element is removed or reduced.
The organic EL lighting device according to claim 1.