Organic EL device

An organic EL device includes an organic EL panel, an ellipsoidal reflector, a phosphor, and a laser. The organic EL panel includes a substrate and at least one organic EL element, and the substrate includes at least one light incident portion on which light is incident from the outside. The ellipsoidal reflector is disposed outside the organic EL panel in such a manner that the phosphor is disposed at a first focal point of the reflector and the light incident portion of the substrate is positioned at a second focal point of the reflector. The laser is disposed outside the organic EL panel in such a manner that the phosphor can be irradiated with a laser beam. Light emitted from the phosphor enters the substrate from the light incident portion. The light emitted from the phosphor that has entered the substrate diffuses in the in-plane direction of the substrate.

This application is a National Stage Entry of PCT/JP2017/007763 filed on Feb. 28, 2017, which claims priority from Japanese Patent Application 2016-096433 filed on May 12, 2016, the contents of all of which are incorporated herein by reference, in their entirety.

TECHNICAL FIELD

The present invention relates to an organic EL device.

BACKGROUND ART

An organic electro-luminescence (EL) panel is a self-emitting panel provided with an organic EL element (organic EL layer), and can be used as a lighting device, a light source, or a display device, for example. The emission color of the organic EL panel is determined by the material of the organic EL layer (light emission layer). Thus, when the organic EL panel is in practical use, the emission color is fixed already. On this account, it is generally impossible for a user to adjust the emission color (to perform color tuning) of the organic EL panel.

Under these circumstances, there has been proposed an organic EL panel configured so that organic EL layers for red, green, and blue (RGB) are formed separately, and color adjustment is achieved by adjusting the balance among the emission intensities of RGB (Patent Literature 1).

CITATION LIST

Patent Literature

Patent Literature 1: JP H2(1990)-44392 A

SUMMARY OF INVENTION

Technical Problem

However, in the organic EL panel with the above-described RGB separation structure, it is necessary to provide the RGB light emission layers separately. The aperture ratio is thus restricted, so that it is difficult to increase the amount of luminous flux emitted from the light emission surface of the organic EL panel. One possible method for increasing the amount of luminous flux is to increase the driving current. This, however, shortens the life of the organic EL panel.

With the foregoing in mind, it is an object of the present invention to provide a novel organic EL device including an organic EL panel adapted to be color tunable by a user, for example.

Solution to Problem

In order to achieve the above object, the present invention provides an organic EL device including an organic EL panel, an ellipsoidal reflector, a phosphor, and a laser. The organic EL panel includes a substrate and at least one organic EL element, and the substrate includes at least one light incident portion on which light is incident from the outside. The ellipsoidal reflector is disposed outside the organic EL panel in such a manner that the phosphor is disposed at a first focal point of the ellipsoidal reflector and the light incident portion of the substrate is positioned at a second focal point of the ellipsoidal reflector. The laser is disposed outside the organic EL panel in such a manner that the phosphor can be irradiated with a laser beam. Light emitted from the phosphor enters the substrate from the light incident portion. The light emitted from the phosphor that has entered the substrate diffuses in an in-plane direction of the substrate.

Advantageous Effects of Invention

The present invention can provide a novel organic EL device including an organic EL panel adapted to be color tunable by a user, for example.

DESCRIPTION OF EXAMPLE EMBODIMENTS

The organic EL device of the present invention will be described specifically below with reference to the accompanying drawings. It is to be noted, however, that the present invention is by no means limited by the following description. InFIGS. 1A to 4to be described below, the same components are given the same reference numerals, and duplicate explanations thereof may be omitted. Also, in the drawings, the structure of each component may be shown in an simplified form as appropriate for the sake of convenience in illustration, and also, each component may be shown schematically with a dimension ratio and the like that are different from the actual dimension ratio and the like.

First Example Embodiment

The present example embodiment is directed to an example of an organic EL device configured so that a substrate has one light incident portion.FIGS. 1A and 1Bshow an organic EL device of the present example embodiment.FIG. 1Ais a plan view showing an example of the configuration of the organic EL device of the present example embodiment.FIG. 1Bis a side view of an organic EL panel included in the organic EL device shown inFIG. 1A, as viewed from a lateral side of the organic EL panel. As shown inFIGS. 1A and 1B, the organic EL device10of the present example embodiment includes an organic EL panel16, an ellipsoidal reflector31, a phosphor32, and a laser51. The organic EL panel16includes a substrate11and an organic EL element13. The substrate11includes at least one light incident portion15on which light is incident from the outside. The ellipsoidal reflector31is disposed outside the organic EL panel16in such a manner that the phosphor32is disposed at a first focal point of the ellipsoidal reflector and the light incident portion15of the substrate11is positioned at a second focal point of the ellipsoidal reflector. The laser51is disposed outside the organic EL panel16in such a manner that the phosphor32can be irradiated with a laser beam52(seeFIG. 3). Light emitted from the phosphor32enters the substrate11from the light incident portion15, and the light emitted from the phosphor32that has entered the substrate11diffuses in the in-plane direction of the substrate11. The organic EL device10of the present example embodiment includes one light incident portion15. The details of the light incident portion15will be described below. While the organic EL panel16shown inFIGS. 1A and 1Bis substantially rectangular, the shape of the organic EL panel is not limited thereto. For example, the shape of the organic EL panel may be a substantially polygonal shape other than the substantially rectangular shape, such as a substantially parallelogram shape (including a substantially square shape and a substantially rhombic shape) other than the substantially rectangular shape, a substantially trapezoidal shape, a substantially pentagonal shape, or a substantially hexagonal shape.

In the organic EL device10, it is only necessary that the organic EL panel16includes at least one substrate11and the organic EL element13, and other configurations are not particularly limited. For example, as shown inFIGS. 1A and 1B, the organic EL panel16may include the first substrate11, a second substrate12, a sealing layer14, and the organic EL element13. In the example shown inFIGS. 1A and 1B, one surface of the first substrate11is a mounting surface on which at least one organic EL element13is disposed. The first substrate11and the second substrate12are laminated in such a manner that the mounting surface of the first substrate11and one surface of the second substrate12face each other with the sealing layer14interposed therebetween. The sealing layer14seals a gap between the first substrate11and the second substrate12along an entire periphery of a region where the first substrate11and the second substrate12face each other.

The ellipsoidal reflector31is configured so that, for example: it has an internal shape corresponding to a partial surface of a spheroid so as to include one of the two focal points (first focal point) of the spheroid; the inner surface thereof is a mirror surface; and it has a function of focusing light emitted from the phosphor32disposed at the first focal point to the other focal point (second focal point). As the ellipsoidal reflector31, any conventionally known ellipsoidal reflector can be used.

As the phosphor32, it is possible to use, for example, a phosphor similar to a phosphor that emits light upon excitation with light emitted from, among phosphor-based light emitting diodes (LEDs), a blue LED or an ultraviolet LED. Examples of the phosphor32include phosphors that emit lights in a visible light region, such as a red phosphor that emits red light, a green phosphor that emits green light, and a blue phosphor that emits blue light.

The laser51is not limited as long as it emits a laser beam in a wavelength range capable of exciting the phosphor32.

The material of the first substrate11is not limited as long as it has a light-transmitting property sufficient to allow light emitted from the organic EL element13(to be described below) and the phosphor32to be radiated to the outside of the organic EL panel16. Examples of the material of the first substrate11include: glass such as alkali-free glass, soda-lime glass, borosilicate glass, aluminosilicate glass, and quartz glass; and polyester resins such as polyethylene naphthalate and polyethylene terephthalate. Preferably, the first substrate11is formed of glass. The size (the length and the width) of the first substrate11is not particularly limited, and can be set as appropriate depending on a desired size of the organic EL panel16, for example. The thickness of the first substrate11also is not particularly limited, and can be set as appropriate depending on the material of the first substrate11, environment in which the first substrate11is used, and the like. Generally, the thickness of the first substrate11is 1 mm or less.

In the first substrate11, the position of the light incident portion15is not particularly limited. As shown inFIG. 1A, the light incident portion15may be at a corner portion on a side surface of the first substrate11(the lower right corner portion inFIG. 1A). The light incident portion15may have any mechanism as long as it allows light emitted from the phosphor32to be incident on the first substrate11from the outside of the organic EL panel16.

As the organic EL element13, a conventionally known and commonly used organic EL element may be used. The organic EL element13, which includes an organic EL layer and a pair of electrodes, is a laminate in which an electrode layer as one of the pair of electrodes, the organic EL layer, and another electrode layer as the other one of the pair of electrodes are laminated in this order, for example. The pair of electrodes is the combination of an anode layer and a cathode layer, for example. The anode layer is a transparent electrode formed of indium tin oxide (ITO) or the like, for example. The cathode layer is a counter electrode formed of a metal or the like, for example. The organic EL layer has a multilayer structure including, in sequence, a hole injection layer, a hole transport layer, a light emission layer containing an organic EL material, an electron transport layer, and an electron injection layer, for example. The organic EL panel16shown inFIGS. 1A and 1Bis of bottom emission type, for example. In the organic EL panel16of bottom emission type, it is preferable that, for example, the organic EL element13is a laminate in which the transparent electrode (anode), the organic EL layer, and the counter electrode (cathode) are laminated in this order from the first substrate11side. AlthoughFIGS. 1A and 1Bshow an example where one organic EL element13is disposed in a central portion on the mounting surface of the first substrate11, the organic EL panel16of the present example embodiment is not limited to this example, and a plurality of (two or more) organic EL elements may be disposed on the mounting surface of the first substrate11. The emission color of the organic EL element13is not particularly limited. For example, when the organic EL panel16is used as a general interior lighting device, the emission color of the organic EL element13may be white or the like. When the organic EL panel16is used as a design-oriented lighting device or an automobile lighting device, the emission color of the organic EL element13may be white, red (R), green (G), blue (B), or the like.

The second substrate12is a sealing substrate for shielding the organic EL element13from the surrounding atmosphere. The second substrate12is not limited as long as it can shield the organic EL element13from the surrounding atmosphere. For example, sealing glass can be used as the second substrate12. The size (length and width) of the second substrate12is not particularly limited, and may be adjusted as appropriate so as to be substantially the same as or slightly smaller than the size of the first substrate11, for example. The thickness of the second substrate12also is not particularly limited. For example, the thickness of the second substrate12is in the range from 0.5 to 1.0 mm.

The sealing layer14is formed by, for example, applying an adhesive along the outer edge of one surface of the second substrate12(the lower surface inFIG. 1B). The adhesive is not particularly limited. For example, an ultraviolet (UV) curable resin or the like can be used suitably as the adhesive. The sealing layer14is formed so as to be slightly thicker than the organic EL element13. For example, the thickness thereof is in the range from 0.1 to 100 μm.

Next, with reference toFIGS. 2A and 2B, how light travels in the organic EL panel shown inFIGS. 1A and 1Bwill be described. As described above, the organic EL device10of the present example embodiment includes the phosphor32. The phosphor32emits light having a color different from the color of light emitted from the organic EL element13. The emission color of the phosphor32is not particularly limited as long as it is different from the emission color of the organic EL element13, and may be any color such as red (R), green (G), or blue (B), for example.

As indicated with a solid-line arrow52inFIG. 2A, a laser beam emitted from the laser51travels in the air toward the phosphor32. The phosphor32is excited by the laser beam, whereby it emits light. As indicated with a solid-line arrow33ainFIGS. 2A and 2B, the light emitted from the phosphor32travels in the ellipsoidal reflector31and is reflected from the inner surface of the ellipsoidal reflector31. Then, as indicated with a solid-line arrow33binFIGS. 2A and 2B, the light from the phosphor32that has been reflected travels in the air toward the light incident portion15. As indicated with a dashed-line arrow33cinFIG. 2B, in the thickness direction of the first substrate11, the light from the phosphor32that has reached the light incident portion15travels inside the first substrate11while being reflected repeatedly from the lower surface and the upper surface of the first substrate11. In the in-plane direction of the first substrate11, as indicated with a dashed-line arrow33cinFIG. 2A, it diffuses throughout the entire surface while being reflected repeatedly from the respective side surfaces of the first substrate11. While the dashed-line arrow33cinFIG. 2Aextends up to the upper side surface of the first substrate11, the light from the phosphor32actually is reflected further from the upper side surface of the first substrate11, and thereafter, the light diffuses throughout the entire surface while being reflected repeatedly from the respective side surfaces of the first substrate11. As indicated with a thick arrow61inFIG. 2B, the light from the phosphor32that has diffused throughout the entire surface is radiated in the air outside the organic EL panel16from the other surface of the first substrate11(the lower surface inFIG. 2B). At this time, emitted light63from the organic EL element13is mixed with the emitted light61, whereby color tuning is achieved.

According to the organic EL device10of the present example embodiment, it becomes possible for a user to adjust the emission color (to perform color tuning) of the organic EL panel16by selecting the phosphor32with emission color necessary for the color tuning, for example. Furthermore, according to the organic EL panel16in the organic EL device10of the present example embodiment, the aperture ratio is not restricted, so that a larger amount of luminous flux is emitted from the light emission surface (the lower surface of the first substrate11inFIG. 2B), as compared with an organic EL panel with the above-described RGB separation structure.

Further, according to the organic EL device10of the present example embodiment in which the ellipsoidal reflector31is disposed outside the organic EL panel16in such a manner that the phosphor32is disposed at the first focal point of the ellipsoidal reflector and the light incident portion15of the substrate11is positioned at the second focal point of the ellipsoidal reflector, it is possible to focus light emitted from the phosphor32on the light incident portion15efficiently.

Still further, according to the organic EL device10of the present example embodiment, instead of causing the sharp laser beam52with a narrow wavelength band to be incident on the light incident portion15directly, light emitted from the phosphor32with a broad wavelength band is caused to be incident on the light incident portion15. This allows a larger energy of light to be utilized.

The organic EL device10of the present example embodiment can be used in a wide range of applications, such as a lighting device of bottom emission type, a light source, and a display device, for example.

Second Example Embodiment

The present example embodiment is directed to an example of an organic EL device configured so that a first substrate includes two light incident portions.FIG. 3is a plan view showing an example of the configuration of an organic EL device of the present example embodiment. As shown inFIG. 3, an organic EL device20of the present example embodiment has the same configuration as the organic EL device10of the first example embodiment, except that the first substrate11further includes a second light incident portion25and that the organic EL device20includes, in addition to the laser51, the ellipsoidal reflector31, and the phosphor32, a second laser81, a second ellipsoidal reflector41, and a second phosphor42disposed near the second light incident portion25. The second light incident portion25has the same shape and mechanism as the light incident portion15. The second light incident portion25is disposed at a corner portion facing the light incident portion15. It is to be noted, however, that the organic EL device20of the present example embodiment is not limited to this example, and the second light incident portion25may be disposed at a different corner portion on a side surface of the first substrate11, for example. The second phosphor42has the same configuration as the phosphor32, except that it emits light having a color different from the colors of lights emitted from the organic EL element13and the phosphor32or it emits light having a color same as the color of light emitted from either the organic EL element13or the phosphor32.

As indicated with a solid-line arrow82inFIG. 3, a laser beam emitted from the second laser81travels in the air toward the second phosphor42. The second phosphor42is excited by the laser beam, whereby it emits light. As indicated with a solid-line arrow43ainFIG. 3, the light emitted from the second phosphor42travels in the ellipsoidal reflector41and is reflected from the inner surface of the ellipsoidal reflector41. Then, as indicated with a solid-line arrow43binFIG. 3, the light from the second phosphor42that has been reflected travels in the air toward the second light incident portion25. In the in-plane direction of the first substrate11, the light from the second phosphor42that has reached the second light incident portion25diffuses throughout the entire surface while being reflected repeatedly from the respective side surfaces of the first substrate11in the same manner as indicated with the dashed-line arrow33cinFIG. 2A. The light from the second phosphor42that has diffused throughout the entire surface is radiated in the air outside the organic EL panel26from the other surface of the first substrate11. Thus, according to the organic EL device20of the present example embodiment, when the emission color of the second phosphor42is different from those of the organic EL element13and the phosphor32, it is possible to mix three emission colors, namely, the emission color of the organic EL element13, the emission color of the phosphor32, and the emission color of the second phosphor42. On the other hand, when the emission color of the second phosphor42is the same as that of either the organic EL element13or the phosphor32, it is possible to mix two emission colors at a ratio different from that in the first example embodiment.

When the organic EL panel in the organic EL device of the present invention is formed in, for example, a substantially hexagonal shape or a substantially octagonal shape, it becomes possible to mix three or more colors with the emission color of the organic EL element by providing three or more light incident portions in the first substrate and using three or more lasers and phosphors.

Third Example Embodiment

The present example embodiment is directed to an example of an organic EL device configured so that a second substrate includes one light incident portion.FIG. 4shows an example of the configuration of an organic EL device of the present example embodiment.FIG. 4is a side view of an organic EL device70of the present example embodiment. As shown inFIG. 4, an organic EL panel in the organic EL device70of the present example embodiment has the same configuration as the organic EL panel16in the organic EL device10of the first example embodiment, except that, instead of a first substrate11, a second substrate12includes a light incident portion15. The organic EL panel shown inFIG. 4is of top emission type, for example. In the organic EL panel of top emission type, it is preferable that, for example, an organic EL element13is a laminate in which the counter electrode (cathode), the organic EL layer, and the transparent electrode (anode) are laminated in this order from the first substrate11side. According to the organic EL device70of the present example embodiment, emitted light61from a phosphor32and emitted light63from the organic EL element13can be radiated from the upper side of the organic EL panel. The organic EL device70of the present example embodiment can be used in a wide range of applications, such as a lighting device of top emission type, a light source, and a display device, for example.

Also in the organic EL device70of the present example embodiment, it is possible to mix two or more colors with the emission color of the organic EL element by providing two or more light incident portions in the second substrate in the same manner as they are provided on the first substrate in the second example embodiment and using two or more lasers and phosphors.

The first to third example embodiments are directed to illustrative examples where the organic EL device is configured so that either the first substrate or the second substrate has the light incident portion(s). It should be noted, however, that the organic EL device of the present invention may be configured so that both the first substrate and the second substrate has the light incident portion(s).

While the present invention has been particularly shown and described with reference to example embodiments, the present invention is not limited to these embodiments. Various changes and modifications that may become apparent to those skilled in the art may be made in the configuration and specifics of the present invention without departing from the scope of the present invention.

This application claims priority from Japanese Patent Application No. 2016-096433 filed on May 12, 2016. The entire disclosure of this Japanese patent application is incorporated herein by reference.

INDUSTRIAL APPLICABILITY

The present invention can provide a novel organic EL device including an organic EL panel adapted to be color tunable by a user, for example. The organic EL device of the present invention can be used in a wide range of applications, such as a lighting device of bottom emission type, top emission type, or the like, a light source, and a display device, for example.

REFERENCE SIGNS LIST