JP2009181880A - Lighting sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting sheet for preventing the occurrence of damage during bending while maintaining a predetermined thinness. <P>SOLUTION: The EL lighting sheet 1 includes a sheet base material 2 having flexibility, and a sheet-like EL light-emitting element 3 having flexibility. The base material 2 has a recessed portion 2a, and the EL light-emitting element 3 is arranged in the recessed portion 2a. A center line 9 in the direction of the thickness of a region where the EL light-emitting element 3 is formed passes through the EL light-emitting element 3. This reduces a load on the EL light-emitting element 3 during bending the EL lighting sheet 1 to suppress the occurrence of damage. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an illumination sheet, and more particularly to an electroluminescence (EL) illumination sheet, and is used as, for example, a lighting component of a display unit or a light-emitting component of a decoration unit in various devices such as portable information terminals and home appliances. The present invention relates to an EL illumination sheet.

  The EL illumination sheet has characteristics such as thinness and flexibility, and this characteristic has been an advantage, and it has been widely used as a light emitting member for display screens of various devices such as portable information terminals and home appliances, and for decoration. ing. In recent years, these devices have diversified designs due to the widespread user preferences and ease of use of functions. In connection with this, also in the EL illumination sheet, it is necessary to form a planar sheet into a three-dimensional (three-dimensional) shape by various processes such as insert molding, vacuum forming, high pressure forming, press forming and simple bending.

  However, when the EL illuminating sheet is formed into a three-dimensional shape by, for example, bending, the EL light emitting element is broken and delaminated in a portion where a large load is applied. Problems such as the generation of black spots and the inability to emit light may occur.

  In the EL light-emitting insert film described in Patent Document 1, in order to prevent attenuation of EL light emission luminance and damage or peeling of the EL light-emitting film in curved surface formation, on one side of the light-transmitting film capable of three-dimensional drawing, An EL light emitting layer composed of a transparent electrode, a phosphor layer, an insulating layer and a back electrode is laminated, and an elastomer resin is contained in each layer constituting the EL light emitting layer.

  In the light emitting device with EL described in Patent Document 2, a front electrode layer, a high dielectric layer, a light emitting layer, a back electrode layer, and a protective layer are provided on the substrate film in order to prevent the EL sheet from being broken during bending deformation. An EL sheet is formed by laminating sequentially, and the back electrode layer and the front electrode layer are made of a material in which needle-like indium-tin oxide (ITO) crystals are dispersed in a resin binder, and the back electrode layer of the EL sheet A resin molded product is integrally provided on the outer surface of the side.

  FIG. 10 is a schematic cross-sectional view of the display device described in Patent Document 3. In the display device 81 described in Patent Document 3, a crack is generated in the inorganic insulating film 86 for sealing the organic EL elements 83 to 85, and the organic EL elements 83 to 85 are deteriorated by moisture or oxygen in the air. In order to prevent this, the first substrate 82, the first electrode 83 formed on the first substrate 82, the organic EL layer 84 formed on the first electrode 83, and the organic EL layer 84 The organic EL elements 83 to 85 having the second electrode 85 formed thereon, the inorganic insulating film 86 formed on the organic EL elements 83 to 85 and sealing the organic EL layer 84, and the inorganic insulating film 86 The first substrate 82 has a second substrate 87 formed thereon, and the neutral axis when the bending stress is applied is positioned in the vicinity of the interface between the inorganic insulating film 86 and the second substrate 87. The material and thickness of the second substrate 87 are set.

Japanese Patent No. 3325216 JP 2003-92189 A International Publication No. 2005/027582 Pamphlet

  The following analysis is given from the perspective of the present invention.

  FIG. 6 shows a schematic cross-sectional view of a general EL illumination sheet according to the background art. In a general EL illuminating sheet 61, an EL light emitting element 63 is disposed on a substrate 62 having a certain thickness for portability and shape maintenance. The EL illumination sheet 61 includes a substrate 62 and an EL light emitting element 63 in which a surface electrode layer 64, a light emitting layer 65, a high dielectric layer (insulating layer) 66, a back electrode layer 67 and a protective layer 68 are laminated on the substrate 62. And comprising. In the case of an EL illuminating sheet molded three-dimensionally, the thickness of the base material 62 is normally required to be 100 μm or more for portability and shape maintenance, and is thicker than the thickness of the EL light emitting element 63. Therefore, a center line 69 (ie, a bisector of the thickness of the EL illumination sheet 61) 69 with respect to the thickness of the EL illumination sheet 61 exists in the substrate 62.

  FIG. 7 is a schematic cross-sectional view showing a state in which the EL lighting sheet 61 shown in FIG. 6 is mountain-folded so that the EL light-emitting element 63 is on the outer peripheral side, and FIG. 8 shows the EL lighting sheet 61 shown in FIG. The schematic sectional drawing which shows the state folded valley | valve so that the light emitting element 63 may become an inner peripheral side is shown. When the EL lighting sheet 61 is bent and deformed, the extension amount of the EL lighting sheet increases from the center line 69 toward the outer peripheral side of the bending, and the EL lighting sheet is pushed from the center line 69 toward the inner peripheral side of the bending. The amount of shrinkage increases. That is, in FIG. 7, since the EL light emitting element 63 exists outside the center line 69 with respect to the thickness, a tensile force is generated in the plane direction (arrow direction) and is expanded. On the other hand, in FIG. 7, since the EL light emitting element 63 exists inside the center line 69 with respect to the thickness, a compressive force is generated in the plane direction (arrow direction) and is compressed.

  At this time, when the EL illumination sheet 61 is bent so that the bending radius of curvature becomes small, the expansion / contraction force (extension amount) or the compression force (compression amount) locally increases. Each layer forming the EL light emitting element 63 is weak in strength and has weak adhesion between the layers. Therefore, the electrode layers 64 and 67, the light emitting layer 65, and the like may break at a place where a large force acts locally, Peeling may occur. Due to the breakage and peeling, the resistance between the electrodes 64 and 67 is significantly increased, and the voltage applied to the light emitting layer 65 is thereby lowered, which causes problems such as a decrease in light emission luminance, generation of black spots, and inability to perform light emission. become.

Here, the difference in the amount of expansion and contraction in the surface direction after bending the single-layer sheet will be described using a single-layer sheet (cuboid shape) as a model of an EL illumination sheet. FIG. 9 shows a schematic diagram of the model. FIG. 9A is a schematic diagram showing a state before bending the sheet 71 having a length L, and FIG. 9B shows that the radius of curvature of the central portion of the thickness is R with respect to the point 72. It is a schematic diagram which shows the state which bent the sheet | seat 71. FIG. Here, the difference between the length on the inner peripheral side and the length on the outer peripheral side (that is, the difference in the amount of expansion / contraction) Ld when the sheet 71 is bent is expressed by the following formula 1. In FIG. 9B, the length (arc length) after bending of the central portion with respect to the thickness is L ₁ , and the length (arc length) after bending of the portion on the outer peripheral side is L ₂ . Also, the distance in the thickness direction between the length L ₁ portion and the length L ₂ portion as a D. Equation 1 means that the amount of expansion and contraction when the sheet 71 is bent depends on the distance D and the radius of curvature R between the outer peripheral side and the inner peripheral side. Equation 1 also shows that the amount of expansion and contraction increases as the radius of curvature R decreases.

[Formula 1]
Ld = | L ₂ −L ₁ | = | {(R ± D) × L ₁ / R−L ₁ } | = D × L ₁ / R

  When this is applied to the EL illumination sheet according to the background art shown in FIG. 6, when the EL illumination sheet 61 is bent, the center line 69 with respect to the thickness of the EL illumination sheet 61 has the smallest expansion / contraction amount (expansion / contraction rate) ( Strictly speaking, the position at which the amount of expansion and contraction is minimized when a laminated and beam-like object is bent depends on the rigidity of each layer, but the difference in rigidity of each layer in the illumination sheet 61 is not large. In the invention, the difference in rigidity of each layer is not taken into consideration.) According to Equation 1, the amount of expansion / contraction of the EL light emitting element 63 increases as the EL light emitting element 63 moves away from the center line 69 with respect to the thickness of the EL light emitting sheet 61. Will increase. Therefore, the layer existing away from the center line 69 with respect to the thickness is subjected to a greater load, and breakage and peeling are likely to occur.

  It is possible to guide the center line 69 on the light emitting element 63 by reducing the thickness of the base material 62 over the entire surface. However, in this case, the base material 62 becomes too thin, so that the illumination sheet can be used. Problems such as portability and reduced shape maintenance after molding occur.

  In the EL light-emitting insert film described in Patent Document 1 and the EL light-emitting device described in Patent Document 2, damage is prevented by improving the material of the EL layer. It has not changed. That is, since the EL layer is at a position deviating from the center line with respect to the thickness, for example, when the bending is performed so that the radius of curvature R is 5 mm or less, the EL layer is broken or broken due to the large extension force or compression force. The possibility of delamination increases. In this case, since the EL illumination sheet cannot be set to have a predetermined radius of curvature or more, restrictions are imposed on the design (three-dimensional shape) applied to the electronic device.

  In the display device described in Patent Document 3, the first substrate 82 needs to have a certain thickness (usually about 100 μm) from the viewpoint of portability and shape maintenance after molding. In addition, the thickness of the second substrate 87 needs to be increased as the thickness of the first substrate 82 increases in order to adjust the position of the neutral axis. That is, the entire thickness of the display device 81 greatly depends on the thickness of the first substrate 82. Therefore, the display device 81 has to be thick as a whole. Further, when the display device 81 becomes thick, there arises a problem that flexibility is lowered.

  The objective of this invention is providing the illumination sheet which can prevent generation | occurrence | production of the damage at the time of bending, maintaining predetermined | prescribed thinness.

  According to a first aspect of the present invention, a flexible sheet-like base material and a flexible sheet-like light emitting element are provided, the base material has a concave portion, and the light emitting element is a concave portion. It is to provide an illumination sheet disposed inside.

  According to the preferable form of the first aspect, the thickness of the base material in the recess is thinner than the thickness of the light emitting element.

  According to a preferred embodiment of the first aspect, the light emitting element has a first electrode layer, a light emitting layer, an insulating layer, a second electrode layer, and a protective layer, and the center line with respect to the thickness of the region where the light emitting element is disposed. Passes through the first electrode layer, the light emitting layer, the second electrode layer, the boundary between the substrate and the light emitting element, or the boundary between the first electrode layer and the light emitting layer.

  According to the preferable form of the first aspect, the thickness of the base material in the recess is 10 μm or more and less than 100 μm.

  The present invention has at least one of the following effects.

  In the present invention, by placing the light emitting element so as to be applied to the center of the thickness of the bent portion, the load applied to the light emitting element at the time of bending (the amount of expansion (stretching rate) and the amount of pressing (pressing rate) of the light emitting device). Is made smaller. Thereby, generation | occurrence | production of the damage (a fracture | rupture, delamination, etc.) in an illumination sheet can be suppressed. That is, it is possible to suppress problems such as a decrease in light emission luminance, black spot generation, and inability to emit light due to the damage.

  Moreover, the width | variety of the three-dimensional shaping | molding of an illumination sheet can be expanded by reducing the load at the time of bending. For example, according to the present invention, the illumination sheet can be bent with a smaller radius of curvature (for example, a radius of curvature of 5 mm or less). Thereby, the freedom degree of the design of the electronic device which uses an illumination sheet can be raised.

  In the present invention, since the position of the light emitting element with respect to the center line of the thickness of the bent region is adjusted by arranging the light emitting element in the concave portion formed in the base material, the position of the light emitting element can be adjusted without forming the concave portion. Compared with the case of adjusting, the illumination sheet can be made thinner. Specifically, according to the present invention, the thickness of the base material under the light emitting element (that is, the thickness of the base material in the recess) is made thinner than the thickness of the base material required for conveyance and shape maintenance. Since the position of the line can be adjusted, the load on the light emitting element can be reduced while reducing the thickness of the entire illumination sheet.

  In the present invention, since the load is adjusted according to the position of the light emitting element, it is not necessary to use a special material for each layer constituting the light emitting element.

  The EL illumination sheet according to the first embodiment of the present invention will be described. FIG. 1 shows a schematic cross-sectional view of the EL illumination sheet according to the first embodiment. The EL illumination sheet 1 includes a substrate 2 and an EL light emitting element 3. A recess 2a is formed in the base material 2, and the EL light emitting element 3 is disposed in the recess 2a. The base material 2 is a light-transmitting resin and may be colorless or colored. For example, as shown in FIG. 1, the EL light emitting element 3 includes a surface electrode layer (first electrode layer) 4, a light emitting layer 5, a high dielectric layer (insulating layer) 6, and a back electrode layer (second electrode layer) 7. , And a protective layer 8 are laminated. The EL light emitting element 3 may be an inorganic material or an organic material.

The recessed part 2a is formed in the part (for example, bending part) which shape | molds the EL illumination sheet 1 in a three-dimensional shape. By disposing the EL light emitting element 3 in the concave portion 2a, the thickness of the base material 2 in the concave portion 2a (the thickness of the base material 2 in the EL light emitting element 3 arrangement portion in FIG. 1) and the thickness of the EL light emitting element 3 are determined. The EL light emitting element 3 can be brought closer to the center line (bisector) (the center line with respect to the thickness of the bent portion) 9 of the total thickness H ₁ . Preferably, the center line 9 passes through the EL light emitting element 3. Thereby, the load to the EL light emitting element 3 applied when the EL illumination sheet 1 is bent can be reduced.

  The depth of the recess 2a or the thickness of the substrate 2 (including the thickness of the recess 2a portion) is adjusted so that the center line 9 preferably passes through a predetermined layer or boundary. In particular, it is preferable to set the center line 9 so as to pass through a lower layer or boundary in terms of strength. For example, it is preferable that the center line 9 passes through the surface electrode layer 4, the light emitting layer 5, or the back electrode layer 7. In particular, a layer formed by vapor deposition has a lower strength than a layer formed by printing or the like, and is therefore preferably located on the center line 9 or in the vicinity thereof. Or since the intensity | strength of the boundary of the base material 2 and the surface electrode layer 4, the boundary of the surface electrode layer 4 and the light emitting layer 5, etc. is low, you may be located on the center line 9 or its vicinity.

  The position of the center line 9 is adjusted by adjusting the depth of the recess 2a or by adjusting the thickness of the substrate 2 in the recess 2a as a method other than changing the thickness of the EL light emitting element 3. be able to. At this time, when the depth of the recess 2 a is deeper than the thickness of the EL light emitting element 3, the exposed surface (protective layer 8) of the EL light emitting element 3 is lower than the upper surface of the substrate 2. For example, as shown in FIG. 1, the recess 10 may be formed by the inner wall side surface of the recess 2 a and the upper surface (protective layer 8) of the EL light emitting element 3.

Here, the EL illuminating sheet 1 according to the present invention and the EL illuminating sheet according to the background art will be compared with respect to the distance between the center line and the EL light emitting element with respect to the thickness of the bent portion (light emitting element and substrate recess). FIG. 4 is a schematic cross-sectional view of an EL illumination sheet according to the background art in which EL light-emitting elements are arranged on a base material having no recess. In the EL illumination sheet 1 of the present invention and the EL illumination sheet 41 according to the background art, the same EL light emitting element 3 is used for comparison. In FIG. 1, the distance between the center line 9 and the surface electrode layer 4 is d ₁ , and the distance between the center line 9 and the back electrode layer 7 is d ₂ . Further, in FIG. 4, the distance between the center line 9 and the back electrode layer 7 and d _5. The distance d ₁ is the sum of the thickness of a part of the light emitting layer 5 and the surface electrode layer 4, and the distance d ₂ is the thickness of a part of the light emitting layer 5, the high dielectric layer 6 and the back electrode layer 7. In contrast, the distance d ₅ is the total thickness of a part of the base material 42, the surface electrode layer 4, the light emitting layer 5, the high dielectric layer 6, and the back electrode layer 7. Accordingly, since the distances d ₁ and d ₂ are shorter than the distance d ₅ , when the EL lighting sheet 1 is bent, the extension force or the pressing force applied to the EL light emitting element 3 (particularly the back electrode layer 7) is the EL lighting sheet. This is less than when 41 is bent.

Next, an EL illumination sheet according to the second embodiment of the present invention will be described. FIG. 2 shows a schematic cross-sectional view of an EL illumination sheet according to the second embodiment of the present invention. In the first embodiment, the depth of the recess 2 a is deeper than the thickness of the EL light emitting element 3, and the exposed surface of the EL light emitting element 3 exists at a position lower than the upper surface of the substrate 2. , The depth of the recess 22 a is shallower than the thickness of the EL light emitting element 3, and the upper surface of the EL light emitting element 3 protrudes from the substrate 22. Here, in the EL illuminating sheet 21, the thickness of the EL illuminating sheet (in FIG. 2, the thickness from the bottom surface of the base material 22 to the top surface of the EL light emitting element 3 = t ₁ + t ₂ ) is H ₂ , and the base material in the recess 22a portion The thickness of 22 (the thickness of the base material 22 of the EL light emitting element arrangement portion) is t ₁ , the thickness of the EL light emitting element 3 is t ₂ , the thickness of the base material 22 is t ₃ , and the back electrode from the center line 9 a thickness of up to layer 7 and d _3.

As a first comparison, in the EL illumination sheet 41 according to the background art shown in FIG. 4 in which the EL light emitting element 3 is arranged on the base material 42 without forming a recess, the thickness of the base material 42 is set to t ₆ , The thickness of the EL light emitting element 3 is t ₇ , and the thickness of the EL illumination sheet 41 is H ₄ (= t ₆ + t ₇ ).

As a second comparison, an EL illumination sheet having the same configuration as the display device described in Patent Document 3 is shown in FIG. The EL illuminating sheet 51 has the same EL light emitting element 3 as the EL illuminating sheet 21 and the like, the thickness of the EL illuminating sheet 51 is H ₅ , the thickness of the first base material 52 is t ₈ , and the EL light emitting element 3. the thickness _{t 9,} and the EL light emitting element 3 the thickness of the upper portion of the second substrate 53 and _{t 10} in. In the EL illumination sheet 51, the center line 9 to the thickness H ₅ of the EL-illuminated sheet, the thickness of the second substrate such that the EL illumination sheet 21 becomes the same position according to the second embodiment shown in FIG. 2 It has set the _{t 10} is.

_Here, taking an example of t 1 _{~t 10,} compares each form. First, in the EL illuminating sheets 21, 41, 51, the same EL light emitting element 3 is used, and t ₂ = t ₇ = t ₉ based on the thickness of the EL light emitting element actually manufactured. = 75 μm. Further, the thicknesses t ₃ , t ₆ , and t ₈ of the base materials 22, 42, and 52 are set to the same thickness of 100 μm on the basis of the normal thickness required for portability and shape maintenance ( Also in Patent Document 3, the thickness of the first base material is 100 μm). Here, in the EL illuminating sheet 21 of the present invention, if the thickness t ₃ of the base material 22 can ensure 100 μm, the portability and the shape maintenance can be secured, so the thickness t ₁ of the base material 22 in the recess 22 a. Can be less than 100 μm, for example 30 μm. Then, since t ₂ = 75 μm, H ₂ = 105 μm. On the other hand, in the EL lighting sheet 51 according to the background art, when the position of the center line 9 passing through the EL light emitting element 3 with respect to the EL light emitting element 3 is the same as the position in the EL lighting sheet 21 of the present invention, the EL lighting is performed. In the sheet 21, the center line 9 is located at a position 22.5 μm (= H ₂ / 2-30 μm) from the lower surface (the bottom surface of the recess 22 a) of the light emitting element, and therefore the center line with respect to the thickness H ₅ of the EL illumination sheet 51. For 9 to be the center, H ₅ = 245 μm and t ₁₀ = 70 μm. Therefore, the thicknesses of the EL illuminating sheets 21, 41 and 51 are H ₂ = 105 μm, H ₄ = 175 μm, and H ₅ = 245 μm, respectively.

First, when the EL illumination sheet 21 of the present invention shown in FIG. 2 is compared with the EL illumination sheet 41 shown in FIG. 4 which is the first comparison reference, the EL illumination sheet 21 of the present invention shown in FIG. According to this, it is possible to reduce the load applied to the center line 9 or a layer in the vicinity thereof at the time of bending. That distance d ₃ even back electrode layer 7 which is positioned farthest from the center line 9 is shorter than the distance d ₅ between the center line 9 and the back electrode layer 7 in the EL illumination sheet 41 according to the background art, the present According to the invention, the load applied to the EL light emitting element 3 at the time of bending can be reduced as compared with the EL illumination sheet 41. Further, even if the overall thickness of the EL illuminating sheet is compared, according to the comparison of the numerical values given in the examples, even if the thicknesses t ₃ and t _{6 of the} base materials 22 and 42 are the same, the present invention This can be made 70 μm thinner than the first comparative control.

Next, when comparing the EL lighting sheet 21 of the present invention shown in FIG. 2 with the EL lighting sheet 51 shown in FIG. 5 as the second comparison reference, all the center lines 9 pass through the same position of the EL light emitting element 3. ing. Therefore, the load applied to the EL light emitting element 3 at the time of bending is the same. However, in the EL illumination sheet 51 according to the background art, the thickness of the first base material 52 (the thickness of the region where the light emitting element 3 and the second base material 53 are not disposed) t for portability and shape maintenance. ₈ above a certain thickness, for example because it must to 100 [mu] m, in order to pass through the light-emitting element 3 to the center line 9 must its bulky even thickness t ₁₀ of the second substrate, EL illumination sheet the total thickness of 51 H ₅ inevitably be thicker. On the other hand, in the EL lighting sheet 21 according to the present invention, the thickness t ₁ of the base material 22 under the EL light emitting element 3 can be less than 100 μm, for example, 30 μm, and the EL lighting sheet 51 according to the background art. Such a second base material is unnecessary, and the entire thickness H ₂ of the EL illumination sheet 21 can also be reduced. That is, in the EL lighting sheet 21 according to the present invention and the EL lighting sheet 51 according to the background art, only twice the difference in thickness of the base material under the EL light emitting element 3 ((t ₈ −t ₁ ) × 2). The total thickness will be different (for example, the difference of H ₅ −H ₂ = 140 μm occurs in the previous example). Therefore, according to the method of adjusting the position of the center line 9 on the EL light emitting element 3 without forming the recess 22a as in the EL lighting sheet 51 shown in FIG. 5, the overall thickness of the EL lighting sheet 51 is increased. Must be thick. Moreover, when the thickness of the EL illumination sheet 51 is increased in this way, the flexibility of the EL illumination sheet and the design of three-dimensional molding are adversely affected.

  Therefore, according to the present invention, the load applied to the EL light emitting element can be reduced without increasing the overall thickness of the EL illumination sheet.

Thus, in the EL illumination sheet 21 of the present invention, _{t 1} (the thickness of the light-emitting element 3 the lower portion of the base member 22) the thickness of the base material 22 in the recess 22a may be less than 100 [mu] m. In particular, in order for the center line 9 with respect to the thickness of the bent portion (the region where the EL light emitting element 3 is disposed) to pass through the EL light emitting element 3, the thickness t ₁ of the base material 22 in the recess 22a is EL It is preferable that the thickness is smaller than the thickness t ₂ of the light emitting element 3. The thickness t ₁ is preferably such that the bottom of the recess 22a is not broken, and is preferably 10 μm or more, for example.

Next, an EL illumination sheet according to the third embodiment of the present invention will be described. FIG. 3 shows a schematic cross-sectional view of an EL illumination sheet according to the third embodiment of the present invention. In the present embodiment, the thickness t ₄ of the base 32 of the recess 32a is, with is thicker than the thickness t ₅ of the EL light emitting element 3, thinner than the substrate 42 of the EL illumination sheet 41 shown in FIG. 4, for example (For example, less than 100 μm). In this case, the center line 9 is not passed through the EL light emitting element 3, passes through the substrate 32 medium under the EL light emitting element 3, the thickness t ₄ of the base material 32 in the recess 32a, the background art since thinner than the thickness t ₆ of the substrate according to the distance d ₄ between the center line 9 and the light-emitting element 3 (e.g. the back electrode layer 7) may be shorter than the distance d ₅ in the background art. Therefore, also in the present embodiment, the load applied to the EL light emitting element 3 can be made smaller in the present invention than in the background art. Further, the thickness H _{3 of the} entire EL illumination sheet 31 can be made thinner than the thicknesses H ₄ and H _{5 of the} illumination sheets 41 and 51 according to the background art.

  In addition, as shown in FIG. 3, the upper surface of the base material 32 and the upper surface of the EL light emitting element 3 may have the same height so as to form the same surface. That is, the depth of the recess 32 a may be the same as the thickness of the EL light emitting element 3.

  Next, the manufacturing method of the EL illumination sheet which concerns on 4th Embodiment of this invention is demonstrated with reference to FIG. First, in the resin base material 2 having light transmittance, the concave portion 2a is formed in a region where the EL light emitting element 3 is formed. Various methods can be applied to the method of forming the recess 2a. For example, the concave portion 2a can be formed on the planar substrate 2 using vacuum forming, high pressure forming, pressing, or the like. Or the base material 2 which has the recessed part 2a can be created by laminating | stacking the upper base material in which the through-hole used as the recessed part 2a was formed on a planar lower base material. Alternatively, the recess 2a can be formed by manufacturing the base material 2 with a film having the same shape as the EL light emitting element 3 interposed in the formation region of the EL light emitting element 3, and then peeling the film.

  Next, the surface electrode layer 4, the light emitting layer 5, the high dielectric layer (insulating layer) 6, the back electrode layer 7, and the protective layer 8 are sequentially laminated inside the recess 2 a of the substrate 2, so that the EL light emitting device 3 is formed, the EL illumination sheet 1 is obtained. The surface electrode layer 4 can be formed by applying a light-transmitting conductive ink by a method such as a screen printing method and then drying or depositing a conductive film by a vacuum evaporation method or the like. . The light emitting layer 5 can be formed by printing a light emitting ink in which a light emitter is uniformly dispersed in a resin paste in the same manner as the surface electrode layer 4, heating and drying. The high dielectric layer (insulating layer) 6 can be formed by printing, heating, and drying an insulating ink obtained by diffusing a high dielectric substance in a resin paste in the same manner as described above. The back electrode layer 7 can be formed by printing, heating, and drying carbon ink in which carbon powder is mixed in a resin paste in the same manner as described above. The protective layer 8 can be formed by printing, heating and drying resin ink in the same manner as described above.

  Note that the light emission operation principle, the constituent material, the three-dimensional shape forming method, and the like of the illumination sheet are well known to those skilled in the art and are not directly related to the present invention, and thus detailed description thereof is omitted.

  The illumination sheet of the present invention has been described based on the above embodiment, but is not limited to the above embodiment, and is within the scope of the present invention and based on the basic technical idea of the present invention. It cannot be overemphasized that various deformation | transformation, change, and improvement can be included with respect to a form. Further, various combinations, substitutions, or selections of various disclosed elements are possible within the scope of the claims of the present invention.

  Further problems, objects, and developments of the present invention will become apparent from the entire disclosure of the present invention including the claims.

  The illuminating sheet of the present invention can be used for lighting parts, ornaments, etc. in display devices of various devices such as electronic devices (for example, portable information terminals), home appliances, and motor vehicles.

1 is a schematic cross-sectional view of an EL illumination sheet according to a first embodiment of the present invention. The schematic sectional drawing of the EL illumination sheet which concerns on 2nd Embodiment of this invention. The schematic sectional drawing of the EL illumination sheet which concerns on 3rd Embodiment of this invention. The schematic sectional drawing of the EL illumination sheet which concerns on background art. The schematic sectional drawing of the EL illumination sheet which concerns on background art. The schematic sectional drawing of the EL illumination sheet which concerns on background art. The schematic sectional drawing of the EL illumination sheet which concerns on background art. The schematic sectional drawing of the EL illumination sheet which concerns on background art. The schematic diagram which shows the model of an illumination sheet. FIG. 6 is a schematic cross-sectional view of a display device according to Patent Document 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 EL illuminating sheet 2 Base material 2a Recessed part 3 EL light emitting element 4 Surface electrode layer 5 Light emitting layer 6 High dielectric material layer 7 Back electrode layer 8 Protective layer 9 Center line 10 Recessed part 21 EL illuminating sheet 22 Base material 22a Recessed part 31 EL illuminating sheet 32 Substrate 32a Concave portion 41 EL illumination sheet 42 Substrate 51 EL illumination sheet 52 First substrate 53 Second substrate 61 EL illumination sheet 62 Substrate 63 EL light emitting element 64 Surface electrode layer 65 Light emitting layer 66 High dielectric layer 67 Back electrode layer 68 Protective layer 69 Center line 71 Model 72 Point 81 Display device 82 First substrate 83 First electrode 84 Organic EL layer 85 Second electrode 86 Inorganic insulating film 87 Second substrate

Claims (4)

A sheet-like base material having flexibility;
A sheet-like light emitting element having flexibility,
The substrate has a recess;
The illumination sheet, wherein the light emitting element is disposed in the recess.   The illumination sheet according to claim 1, wherein a thickness of the base material in the recess is thinner than a thickness of the light emitting element. The light emitting element has a first electrode layer, a light emitting layer, an insulating layer, a second electrode layer, and a protective layer,
The center line with respect to the thickness of the region where the light emitting element is disposed is the first electrode layer, the light emitting layer, the second electrode layer, the boundary between the base material and the light emitting element, or the first electrode layer. The illumination sheet according to claim 1, wherein the illumination sheet passes through a boundary of the light emitting layer.   The thickness of the said base material in the said recessed part is 10 micrometers or more and less than 100 micrometers, The illumination sheet as described in any one of Claims 1-3 characterized by the above-mentioned.

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