JP5701404B2 - Illumination device including organic electroluminescence element - Google Patents

Description

  The present invention relates to an illumination device including an organic EL panel using an organic electroluminescence (hereinafter referred to as organic EL) element.

  In recent years, organic EL panels, which are self-luminous elements, have been used in lighting devices in various modes as planar light sources (see Patent Documents 1 to 7).

  A white light emitting organic EL panel is often used as an illumination device. The white light emitting organic EL panel can be configured by arranging a plurality of red light emitting R, green light emitting G, and blue light emitting B regions, that is, RGB subpixels, in a predetermined order on a substrate.

Japanese Utility Model Publication No. 01-145640 Japanese Utility Model Publication No. 02-52218 Japanese Patent Laid-Open No. 03-241285 JP 09-115667 A JP 2004-031341 A JP 2009-009872 A JP 2009-206030 A

  However, when the white light emitting organic EL panel is manufactured with a wide pitch of RGB subpixels, the RGB subpixel itself becomes conspicuous, and the color mixture of RGB light emitting colors becomes insufficient, resulting in an organic EL panel with RGB light emitting colors. There is a problem that it ends up. On the other hand, when the RGB sub-pixel pitch is made narrow, the aperture ratio of the RGB sub-pixel becomes small, so that the current load on each element for obtaining the desired white luminance becomes large, and the organic EL panel is manufactured. There is a problem that the yield also deteriorates.

  Therefore, in the present invention, an example of a problem is to provide an illumination device that can sufficiently achieve a mixed color of RGB emission colors while maintaining an aperture ratio.

  The present invention is an illumination device including an illumination panel and a housing that houses the illumination panel and has an opening that extracts the illumination light of the illumination panel to the outside. The illumination panels are arranged in parallel in a stripe shape. It has at least one planar light emitting portion composed of a plurality of strip-shaped organic EL elements of different emission colors, and the longitudinal direction of the plurality of strip-shaped organic EL elements is parallel to the plane including the opening, and the planar light emitting portion Are inclined with respect to a plane including the opening.

It is a schematic perspective view which shows the illuminating device of the Example of this invention. It is sectional drawing of the AA line in FIG. It is a top view of the organic electroluminescent panel seen from the board | substrate side direction which comprises the organic electroluminescent panel of the Example of this invention. It is sectional drawing along CC line in FIG. It is a diagram for demonstrating the relationship between the sub pitch Sp of the organic EL element of this invention, and an observer. It is a schematic perspective view which shows the illuminating device of the other Example of this invention. It is a graph which shows the radiance distribution of the organic electroluminescent panel used for the illuminating device of the other Example of this invention. It is a schematic perspective view which shows the illuminating device of the other Example of this invention. It is a schematic sectional drawing which shows the illuminating device of the other Example of this invention. It is a schematic sectional drawing which shows the illuminating device of the other Example of this invention. It is a schematic perspective view which shows the illuminating device of the other Example of this invention. It is a schematic sectional drawing which shows the illuminating device of the other Example of this invention. FIG. 13A is a plan view showing a structure of a lighting device according to another embodiment of the present invention, and FIG. 13B is a cross-sectional view taken along line DD in FIG.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a schematic perspective view showing a first embodiment of a lighting device 11 attached to a ceiling. FIG. 2 is a cross-sectional view taken along line AA in FIG. FIG. 2 shows a state when the lighting device 11 is used. In FIG. 2, the downward direction of the lighting device 11 is the light extraction direction. Here, although it demonstrates as what installs the illuminating device 11 in a ceiling, you may install not only in what is arrange | positioned in a ceiling, for example in the wall surface perpendicular | vertical to a floor surface, walls other than a ceiling.

  The lighting device 11 includes an outer housing 12. The housing 12 stores the organic EL panel 13 and the like inside. The housing 12 is provided with an opening 14 for taking out the illumination light of the organic EL panel 13 to the outside. A flange FL is provided around the opening 14 of the housing 12 so as to serve as an attachment to the ceiling.

  As shown in FIG. 1, the organic EL panel 13 includes a planar light emitting portion 13 </ b> A composed of a plurality of strip-shaped organic EL elements 13 a having different emission colors arranged in parallel in a stripe shape. In FIG. 1, the planar light emitting portion 13A of the set of organic EL elements 13a is indicated by hatching parallel to the stripe extending direction. The organic EL panel 13 is fixed to the housing 12 via a panel support 15 fixed to the housing 12. The organic EL panel 13 is fixed to the panel support 15 with screws or the like, for example. The method for fixing the organic EL panel 13 is not particularly limited.

  As the organic EL panel 13, for example, a planar one extending in the panel plane xy direction is used, and the organic EL panel 13 is arranged so that the surface light emitting part on the light extraction side of the organic EL panel can be seen by the observer from the opening 14. ing. In particular, as shown in FIGS. 1 and 2, the organic EL panel 13 is disposed so as to be inclined at an angle θ in the depth direction Z from the XY plane (opening plane XY direction) including the opening 14 of the housing 12. .

Further, the organic EL panel 13 is fixed to the housing 12 so that the respective longitudinal directions of the organic EL elements 13 a are parallel to the opening plane XY including the opening 14 of the housing 12. If the lighting apparatus 11 directly below the observer views the organic EL panel 13 through the opening 14, the observer not a stripe-shaped organic EL element 13a from the normal direction of the panel plane xy direction, then inclined The organic EL panel 13 is viewed from the direction.

  As shown in FIG. 2, the drive circuit 16 can be disposed on the inner surface of the housing 12 on the back side of the organic EL panel 13 in the depth direction Z of the housing 12. The drive circuit 16 is an electric circuit that is connected to an external power supply line and supplies power to the organic EL panel 13. The drive circuit 16 may be configured to drive the plurality of organic EL elements 13a (light emitting elements) of the organic EL panel 13 under different conditions for each emission color. The drive circuit 16 and the organic EL panel 13 are connected by a conductive cable Cc.

  When the lighting device 11 is used as a lighting module for lighting equipment, the flange FL and the drive circuit 16 are not necessarily provided around the opening 14 shown in FIG. 2, and other external fixing means and power supply means are provided. be able to. In the organic EL panel, two power supply lines to the organic EL panel are required for at least the anode and the cathode. In addition, when an organic EL panel in which a plurality of light emitting elements are arranged is used, if it is desired to drive each light emitting element under different conditions, three or more power supply lines are required.

[Organic EL panel 13]
FIG. 3 is a plan view of the organic EL panel 13 viewed from the substrate side direction (panel normal direction z) constituting the organic EL panel of the present embodiment. FIG. 4 is a cross-sectional view taken along the line CC in FIG. 3 showing the configuration of the organic EL panel 13.

  As shown in FIG. 3, in the organic EL panel 13, the organic EL elements 13 a juxtaposed in a parallel stripe pattern are, for example, organic EL elements having different emission colors of red light emission R, green light emission G, and blue light emission B. The group (also referred to as RGB stripes) can be sequentially arranged. In other words, the organic EL element 13a has the pitch Lp of the RGB emission color groups and the sub-pitch Sp in each group (the total of the width in the short side direction and the bank width of the organic EL elements 13a. (The width is short), and they are juxtaposed in the x direction at regular intervals.

  As shown in FIG. 4, the organic EL panel 13 includes a light-transmitting substrate 20, such as glass and resin, a transparent electrode 30, a bus line 40, an organic layer 50 including a light emitting layer, and a reflective electrode 60. It is constructed by stacking. The organic EL panel 13 is a so-called bottom emission type organic EL panel that takes out light generated in the light emitting layer from the surface of the substrate 20 by applying a voltage between the transparent electrode 30 and the reflective electrode 60. The light extraction surface of the substrate 20 is a flat surface, and the organic EL element 13 a is provided on the surface opposite to the light extraction surface of the substrate 20.

  The plurality of transparent electrodes 30 constituting the anode each have a strip shape, extend along the y direction on the substrate 20, and are juxtaposed in parallel to the x direction at a constant interval. Each of the transparent electrodes 30 is made of a metal oxide conductor such as ITO (Indium Tin Oxide) or IZO (Indium Zinc Oxide).

  A bus line 40 for supplying a power supply voltage to the transparent electrode 30 is formed on each end side of the transparent electrode 30 so as to extend along the y direction.

  An insulating film BK is formed on the bus line 40 of the substrate 20 and the transparent electrode 30. In the insulating film BK, stripe-shaped openings each extending in the y direction are formed. A plurality of banks (partition walls) are formed by providing a plurality of openings on the surface of the insulating film BK. Each of the openings reaches the transparent electrode 30, and the surface of each transparent electrode 30 is in contact with the organic layer 50 at the bottom of the opening.

  On the transparent electrode 30 in each opening of the insulating film BK, a hole injection layer 51, a hole transport layer 52, light emitting layers 53R, 53G, 53B, an electron transport layer 54, and an electron injection layer 55 are stacked in this order. An organic layer 50 configured as described above is formed. A hole blocking layer may be provided between the light emitting layer and the electron transport layer.

  The light emitting layers 53R, 53G, and 53B are made of a fluorescent organometallic compound that emits red light, green light, and blue light, respectively. The light emitting layers 53R, 53G, and 53B are juxtaposed in a state of being separated from each other by an insulating film BK (bank). That is, the organic layer 50 forms a plurality of light emitting regions separated by the bank BK. These light emitting regions and the like can be formed by applying and drying droplets of light emitting materials of at least two colors corresponding to the respective light emitting color light emitting layers individually by an ink jet method.

  An electron transport layer 54 and an electron injection layer 55 are sequentially formed so as to cover the surfaces of the light emitting layers 53R, 53G, 53B and the insulating film BK. A strip-like reflective electrode 60 constituting a cathode is formed so as to extend in the x direction so as to cover the surface of the electron injection layer 55. The reflective electrode 60 is made of a metal such as Al or an alloy having a low work function and high reflectivity. The reflective electrode 60 constitutes a light reflecting film.

  In the layer configuration of the organic functional layer such as the light-emitting layer described above, it is possible to stack the constituent elements other than the substrate in the reverse order. In any case, the structure of the organic layer and the electrode including the charge transport layer that includes at least the light emitting layer or can also be used is included in the present invention, without being limited to these stacked structures.

  In this manner, the light emitting layers 53R, 53G, and 53B that emit red, green, and blue light emission colors are repeatedly arranged in a stripe shape, and the red, green, and blue light is emitted from the surface of the substrate 20 that serves as a light extraction surface. Are mixed at an arbitrary ratio to emit light that is recognized as a single emission color.

[Operation of lighting device]
In the RGB stripe type organic EL panel 13 of the present embodiment, when the pitch of the organic EL elements of the RGB light emission color of the organic EL element 13a is wide such as the pitch Lp and the sub-pitch Sp, the RGB stripes become conspicuous and the RGB light emission color. There is a concern that the mixed color becomes inadequate and cannot be seen by the white organic EL panel 13. On the other hand, when the pitch of the organic EL elements 13a is narrowed, the area of the bank BK is relatively increased and the aperture ratio is decreased. Therefore, when a desired luminance is obtained, a current load applied to each element increases. Further, when the pitch is narrowed, the number of organic EL elements 13a increases, so that there is a concern that the manufacturing yield of the organic EL panel is deteriorated and the productivity is deteriorated.

  As shown in FIG. 5, even when the user of the lighting device directly looks at the lighting device, the distance from the observer V who is the user to the organic EL panel 13 is considered to be 1 m (1000000 μm) or more. .

  When the distance between the user and the panel is 1 m, consider a panel pitch at which this distance becomes the minimum viewing distance (distance that can be seen by human eyes by mixing the three primary colors). At this time, the pixel pitch of the panel from a place 1 m away from the panel is 4 ′ (0.066 °), and the pixel pitch = 2 × (tan (0.033 °) × 1000000) ≈1150 μm. Therefore, sub pitch 2X / 3: Sp = (pixel pitch) / 3≈380 μm. That is, in lighting applications (distance to the panel is 1 m or more), the 380 μm pitch is a pitch at which RGB stripes cannot be recognized.

  Thus, the RGB stripes can be made difficult to be seen by installing the organic EL panel 13 obliquely in the housing 12 with respect to the XY plane including the housing opening 14. In addition, although it demonstrated to the RGB color stripe of the three primary colors which comprise white, a stripe is not specifically limited to RGB.

  Assuming that an aperture ratio of 90% or more is to be secured, as shown in Table 1, the sub-pitch Sp (calculated when the bank width is 70 μm) of the organic EL panel 13 is required to be 700 μm or more.

  Since RGB stripes cannot be seen at a sub-pitch Sp of 380 μm, Sp = 700 μm is substituted and calculated in order to satisfy cos θ = 380 / Sp [μm]. In order to set the 700 μm pitch organic EL panel 13 to the sub-pitch Sp where the RGB stripe is not visible when viewed from the observer of FIG. 5, it is necessary to tilt the organic EL panel 13 by an inclination angle θ = 57.1 ° or more. In this case, if Sp × cos θ ≦ 380 μm is satisfied, the effect of making the RGB stripe invisible to the observer becomes remarkable. Table 2 shows the calculated inclination angle θ satisfying cos θ = 380 / Sp.

  Thus, in this embodiment, the organic EL panel 13 (xy plane) is arranged obliquely (inclination angle) with respect to the XY plane including the opening 14 in the housing 12 that houses the RGB stripe type organic EL panel 13. θ) makes it possible to make the RGB stripes invisible to the observer, and the pitch is not narrowed indefinitely, thereby reducing the number of organic EL elements 13a and contributing to the manufacturing yield.

[Second Embodiment]
When the radiance distribution of the organic EL panel 13 is a strong light intensity distribution in the front direction of the organic EL panel 13 or a normal Lambertian light intensity distribution, the amount of light reaching the observer from the organic EL panel 13 installed obliquely from the opening plane Becomes weaker. Further, even if the light in the front direction is reflected by a mirror or the like, the light is RGB stripe light with a pitch of 700 μm.

  Therefore, efficient light extraction can be achieved by applying a mirror finish to the inner wall of the housing 12 shown in FIG. 1, at least the inner wall from the organic EL panel 13 to the opening 14.

  Further, the apparatus shown in FIG. 6 includes a mirror M that intersects the organic EL panel 13 and faces a plane including the opening 14 of the housing 12 (a mirror whose intersection line with the organic EL panel is parallel to the opening plane). The embodiment is the same as the configuration shown in FIG. 1 except that it also has an efficient light extraction. In particular, when the organic EL panel has a strong radiance distribution in an oblique direction at an angle b ° from the vertical direction (panel normal direction z) of the organic EL panel 13, the crossing angle 180-b ° (with respect to the organic EL panel 13) If the mirror M is arranged at an angle formed by the mirror M and the organic EL panel 13, an effect of reducing light loss in the observation direction can be obtained.

  Furthermore, the organic EL element 13a may be formed to have a radiance distribution other than that of the normal plane, which is higher in intensity than the radiance distribution in the normal plane including the organic EL element 13a of the organic EL panel 13 during driving. preferable. The organic EL panel 13 installed obliquely by optically designing the organic layer of the organic EL element 13a so as to have a strong radiance distribution from the organic EL panel 13 toward the observer (oblique from the front of the organic EL panel 13). The light extraction can be made effective as compared with the case of using one having a strong radiance distribution in the normal direction.

  Therefore, the results of an experiment in which two types of organic EL panel having a Lambertian light intensity distribution and an organic EL panel having a strong radiance distribution obliquely from the normal direction of the panel are created and evaluated will be described.

  The layer configuration of the cathode (reflecting electrode), the light emitting layer, the hole transport layer, the hole injection layer, and the anode (transparent electrode) in the organic layer configuration shown in FIG. 4 was formed on a glass substrate having a thickness of 1.1 mm. . In the one having a Lambertian light intensity distribution (60:45 elements) and the one having a strong radiance distribution obliquely from the panel normal direction (120: 10 elements), only the film thickness of the light emitting layer and the hole transport layer is obtained. Two types of organic EL panels were formed with the same configuration except that the ratio was changed.

  Table 3 shows the layer structure.

  Next, with reference to FIG. 7, an experiment for examining optical characteristics of 120: 10 element and 60:45 element organic EL panels will be described. Both the 120: 10 element and 60:45 element organic EL panels exhibited a broad spectrum with an emission wavelength of approximately 500 nm peak (5 V). The distribution of the radiance at this time with respect to the emission angle was measured for a 120: 10 element organic EL panel and a 60:45 element organic EL panel. The radial direction of the graph shown in FIG. 7 indicates radiance, and the circumferential direction indicates the emission angle. Curves 120: 10 and 60:45 show the radiance distributions of the 120: 10 element and 60:45 element organic EL panels, respectively.

  As can be seen from the radiance distribution, in the organic EL panel having 60:45 elements, the radiance was uniform in almost all emission angle ranges. In the 120: 10 element organic EL panel, the radiance at an emission angle of about 45 ° was improved as compared with the former case.

  As described above, a 60:45 element organic EL panel having a Lambertian light intensity distribution may be used obliquely with respect to the housing opening XY plane, but has a strong radiance distribution in the normal oblique direction. Further, it can be seen that the optical extraction of the organic EL panel obliquely installed can be made effective by optically designing the organic layer of the organic EL panel. Furthermore, if the mirror is arranged in the direction of strong radiance distribution in which the organic EL panel is unevenly distributed, strong light extraction from the organic EL panel in the observer direction can be achieved. That is, it is preferable that the organic EL element is formed so that the radiance distribution has a maximum value except for the normal plane along the longitudinal direction.

  In a housing for housing an RGB stripe organic EL panel, when the organic EL panel is disposed obliquely with respect to the XY plane including the opening, the organic EL panel is in the observer direction (the oblique direction of the organic EL panel). ) Is preferably optically designed so that the radiance distribution is strong.

[Third embodiment]
In FIG. 8, two organic EL panels 13 are electrically connected through a fixing member (not shown) so that the light extraction surface of the organic EL element faces the opening 14 in one housing 12. The embodiment same as the configuration shown in FIG. 2 and FIG. It arrange | positions so that the intersection line of organic EL panels may become parallel to the said opening plane.

  In FIG. 9, eight organic EL panels 13 are electrically connected via a plurality of fixing members 70 so that the light extraction surface of each organic EL element faces the opening 14 in one housing 12. The embodiment same as the configuration shown in FIG. 2 is shown except that it is connected and fixedly arranged like a bellows. Since the organic EL element 13a (reflecting electrode) also functions as a mirror, efficient light extraction in the front direction can be achieved.

  FIG. 10 shows an organic EL panel 13b using a single flexible substrate in an accordion-like manner so that the light extraction surface of each organic EL element faces the opening 14 in one housing 12. The same embodiment as that shown in FIGS. 2 and 9 is shown except that the planar light emitting portion 13A is formed so as to be inclined with respect to the opening plane.

  In FIG. 11, four triangular organic EL panels 13 are arranged through a fixing member (not shown) so that the light extraction surface of each organic EL element faces the opening 14 in one housing 12. The same embodiment as that shown in FIG. 2 is shown except that it is electrically connected and fixedly arranged in a quadrangular pyramid shape. Since the organic EL element 13a also functions as a mirror, efficient light extraction in the front direction can be achieved.

[Fourth embodiment]
In FIG. 12, in order to suppress the visual recognition of light emission from the normal direction of the organic EL panel 13, a flange EAV protruding in parallel with the stripe extending direction of the organic EL element 13a is provided at the peripheral edge of the opening 14. Except for this, the same embodiment as that shown in FIG. 12 is shown. It should be noted that the flange EAV protruding in parallel with the stripe extending direction of the organic EL element 13a can be provided in any of the embodiments.

[Fifth embodiment]
FIG. 13A is a plan view showing a lighting device structure of a fifth embodiment of the present invention, and FIG. 13B is a cross-sectional view taken along the line DD in FIG.

  FIG. 13 shows a modification of the embodiment shown in FIG. 11, in one housing 12, twelve two sheets are centered so that the light extraction surface of each organic EL element faces the light emitting surface toward the opening 14. An equilateral triangular organic EL panel 13c is arranged around the respective isosceles apex angles, and the bottom and top sides of 36 trapezoidal organic EL panels 13d are alternately connected via a fixing member (not shown). FIG. 11 shows an embodiment identical to that shown in FIG. 11 except that they are connected and fixedly arranged concentrically. In this example, the organic EL element 13a also functions as a mirror, so that efficient light extraction in the front direction can be achieved. By arranging a plurality of organic EL panels in the chandelier type, it is possible to suppress variation in luminance depending on the position of the observer. In this embodiment, a collar portion (not shown) may be provided in the same manner as in the fourth embodiment.

  In any of the embodiments, for protection, a transparent lid member such as glass or acrylic, or a grid made of metal, resin, or the like may be disposed in the housing opening 14.

DESCRIPTION OF SYMBOLS 11 Illuminating device 12 Housing 15 Panel support part 13 Organic EL panel 14 Opening part 16 Drive circuit 20 Board | substrate 30 Transparent electrode 40 Bus line 50 Organic layer 53R, 53G, 53B Light emitting layer 60 Reflective electrode BK Insulating film Cc Cable connector

Claims (6)

A lighting device comprising: a lighting panel; and a housing that houses the lighting panel and has an opening for taking out the illumination light of the lighting panel to the outside,
The lighting panel includes at least one flat light extraction surface,
The flat light extraction surface, a plurality of strip-shaped organic EL elements of different luminescent colors from each other in parallel juxtaposed stripes,
The longitudinal direction of the plurality of strip-shaped organic EL elements is parallel to a plane including the opening, and the flat light extraction surface is disposed to be inclined with respect to the plane including the opening. Lighting device.   2. The lighting device according to claim 1, wherein the organic EL element has a local maximum radiance distribution at a driving time other than a normal plane along a longitudinal direction of the organic EL element. The angle θ formed by the plane including the opening and the flat light extraction surface satisfies Sp × cos θ ≦ 380 [μm], where Sp is the periodic interval between the adjacent organic EL elements. The lighting device according to claim 2.   The lighting device according to claim 2, wherein at least a part of the inner wall of the housing is mirror-finished. Intersecting the flat light extracting surface, and, according to claim 2, line of intersection of said flat light extraction surface, characterized in that it further comprises at least one plane mirror parallel to a plane including the opening Lighting device. Intersecting the flat light extracting surface, and the illumination device according to claim 2, line of intersection of said flat light extraction surface, characterized by further comprising a parallel additional lighting panel in a plane containing the opening .

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