HK1120700A - A luminescent sheet and method of producing the same - Google Patents

Description

Light emitting sheet and method for manufacturing the same

Technical Field

The present invention relates to a light-emitting sheet in which an EL (electroluminescence) material is used.

Background

An EL sheet is one example of a light emitting device that has recently received attention. EL sheets have been known to have features of ease of manufacture and high durability. Thus, they have been used in various fields relating to advertising media, lighting use, decoration use, backlight use, and the like.

When used for the above purpose, the EL sheet is used for a long time in many cases, and thus a serious problem occurs with respect to power consumption. Thus, it has been attempted to achieve low power consumption by utilizing a technique of improving luminous efficiency by allowing a plurality of light sources to flash or by causing diffuse reflection of light, for example, as described in japanese patent laid-open (kokai) No.11-45062a (1999), japanese patent laid-open (kokai) No.2005-108776A, and japanese patent laid-open (kokai) No. 2002-196705A. However, the method disclosed in the above document requires a highly complicated structure and driving control.

Disclosure of Invention

An object of the present invention is to provide a low power consumption light emitting sheet obtained in a more convenient manner.

The invention is summarized as follows:

(1) a light-emitting sheet obtained by allowing a sheet capable of causing light emission to be subjected to a perforation treatment.

(2) The light-emitting sheet according to item (1), wherein the sheet capable of causing light emission is an electroluminescent sheet.

(3) The light-emitting sheet according to the item (1) or (2), wherein the hole area ratio is 5% to 80%.

(4) The light-emitting sheet according to any one of the items (1) to (3), wherein the hole diameter at the time of the perforation treatment is 0.1 to 20mm and the interval length between the hole centers is 0.2 to 50 mm.

(5) The light-emitting sheet according to any one of items (1) to (4), which has been subjected to a perforation process in a matrix pattern.

(6) The manufacturing method of a light-emitting sheet according to any one of the items (1) to (5), comprising allowing a sheet capable of causing light emission to be subjected to a punching treatment.

(7) The method according to item (6), wherein the perforation treatment means used is drilling, heated needle treatment, punching, flat die cutting, rotary die cutting or laser treatment.

Effects of the invention

According to the present invention, a low power consumption light emitting sheet obtained in a more convenient manner can be provided.

Drawings

Fig. 1 shows a cross-sectional view of an unperforated luminescent sheet.

Fig. 2 shows a case where the punching process is performed from the second electrode (back electrode) layer side.

Fig. 3 shows a formula for determining the aperture area ratio of the associated perforation process pattern.

Fig. 4 shows a formula for determining the aperture area ratio of the associated perforation process pattern (next to fig. 3).

The various numbers in the figures represent the following:

1-transparent substrate

2-first electrode (transparent electrode) layer

3-luminescent layer

4-dielectric layer

5-second electrode (Back electrode) layer

Detailed Description

The light-emitting sheet of the present invention is a sheet capable of causing light emission, which has been subjected to a perforation treatment. By performing the punching process of the sheet capable of causing light emission, a low-power-consumption light-emitting sheet can be obtained. Further, by adjusting the hole diameter and the hole area ratio at the time of the punching process, the luminance reduction can be significantly prevented.

Preferred examples of the above sheet capable of causing luminescence include an electroluminescent sheet.

When an electroluminescent sheet is used as the sheet capable of causing light emission, an example thereof is an electroluminescent sheet comprising a transparent substrate on which at least a first electrode (transparent electrode) layer, a light-emitting layer, and a second electrode (back electrode) layer are formed.

The above-mentioned transparent substrate is not particularly limited as long as it is transparent. However, it is preferred that such transparent substrate is flexible. Examples of materials for such a transparent substrate include: polyesters such as polyethylene terephthalate, polybutylene terephthalate, or polyethylene naphthalate (polyethylene naphthalate); wholly aromatic polyanilides (perhalolyaromatic polyamides); aliphatic polyamides such as nylon 6, nylon 66, or nylon copolymers; polymethyl methacrylate; and a polycarbonate. The thickness of the substrate film to be used is not particularly limited and is usually 1 to 1000. mu.m, preferably 5 to 500. mu.m, particularly preferably 50 to 200. mu.m for practical use.

Examples of the material for the first electrode layer include, but are not particularly limited to, metals, alloys, metal oxides, conductive organic compounds, and mixtures thereof. Specific examples thereof include: semiconductive metal oxides such as tin oxide doped with antimony, fluorine, or the like (for example, ATO or FTO), tin oxide, zinc oxide, Indium Tin Oxide (ITO), or Indium Zinc Oxide (IZO); metals such as gold, silver, chromium or nickel; mixtures or stacks of such metals and conductive metal oxides; conductive inorganic substances such as copper iodide or copper sulfide; conductive organic materials such as polyaniline, polythiophene, or polypyrrole; and the above examples and a stack of ITO. The thickness of the first electrode layer is typically 50 to 50000 nm.

The first electrode layer and the second electrode layer may be formed on the above substrate according to a method appropriately selected from, for example, the following methods based on materials suitable for the above materials: wet processes such as printing processes and coating processes; physical methods such as a vacuum deposition method, a sputtering method, and an ion plating method; and chemical methods such as a thermal CVD (chemical vapor deposition) method, a plasma CVD method, and a photo CVD method.

According to the present invention, a light-emitting layer is provided between a first electrode layer and a second electrode layer. The light emitting layer may be formed in a planar layer in such a manner that the light emitting layer covers one surface of each electrode layer. Alternatively, the light emitting layer may be partially provided.

The material for the light-emitting layer is not particularly limited as long as it is used to cause light emission upon application of an electric fieldMaterials for optical phenomena. Examples of such materials that can be used include: inorganic EL materials, e.g. active zinc sulfide ZnS: X (where X is an activator element, e.g. Mn, Tb, Cu, Sm or Ag), Y₂O₂S:Eu、Y₂O₃:Eu、Zn₂SiO₄:Mn、CaWO₄:Pb、BaMgAl₁₀O₁₇:Eu、CaS:Eu、SrS:Ce、SrGa₂S₄:Ce、CaGa₂S₄:Ce、CaS:Pb、BaAl₂S₄Eu or YVO₄Eu; low molecular weight organic EL materials such as aluminum-quinolinol complex (aluminum-quinolinol complex) or aromatic diamine derivatives (e.g., triphenyldiamine (triphenyldiamine) derivatives); and polymer organic EL materials such as polyphenylene 1, 2-vinylene (polyphenylenevinylene). The thickness of the light-emitting layer is not particularly limited; however, it is usually 5 to 100 μm and preferably 10 to 80 μm in terms of easy handling. For example, when an inorganic EL material is used, preferable examples of a method of forming a light emitting layer include a bar coating (bar coating) method, a hob coating method, a gravure coating method, a knife coating method, a spin coating method, a dip coating method, a screen printing method, a slide coating method, and a sputtering method. When an organic EL material is used, a vacuum deposition method as well as an inkjet method can be used.

According to the present invention, it is preferable to provide a dielectric layer for improvement of luminous efficiency. A dielectric layer is provided between the first electrode layer and the second electrode layer and preferably between the light emitting layer and the second electrode layer. Preferred examples of materials for the dielectric layer include insulating materials having a high dielectric constant, such as TiO₂、BaTiO₃、SrTiO₃、PbTiO₃、KNbO₃、PbNbO₃、Ta₂O₃、BaTa₂O₆、LiTaO₃、Y₂O₃、Al₂O₃、ZrO₂AlON, ZnS, silicon oxide, silicon nitride or antimony doped tin oxide. The thickness of the dielectric layer is not particularly limited; however, it is usually 5 to 100 μm and preferably 10 to 80 μm in terms of easy handling. As appropriate selected, e.g., based on the applicationThe following methods of forming the material may form a dielectric layer on the substrate: wet processes such as printing processes and coating processes; physical methods such as a vacuum deposition method, a sputtering method, and an ion plating method; chemical methods such as a thermal CVD (chemical vapor deposition) method, a plasma CVD method, and a photo CVD method. Preferred examples of the method of forming the dielectric layer include a bar coating method, a hob coating method, a gravure coating method, a knife coating method, a spin coating method, a dip coating method, a screen printing method, a slide coating method, and a sputtering method.

The material for the second electrode layer is not particularly limited as long as it is a conductive material. Examples of such a material include a metal film made of a conductive paste or formed by physical deposition, and the above-described material for the first electrode layer. The thickness of the second electrode layer is typically 50 to 50000 nm. Preferred examples of the method of forming the second electrode layer include a bar coating method, a hob coating method, a gravure coating method, a knife coating method, a spin coating method, a dip coating method, a screen printing method, a slide coating method, and a sputtering method.

After the second electrode layer is formed, an adhesive sheet or the like serving as a protective layer for the second electrode layer is applied to the second electrode layer, and thus a sheet capable of causing light emission having a light-emitting surface which is one surface of a transparent substrate can be obtained.

If necessary, a design may be imparted to the light emitting surface by printing a pattern, text, or the like directly on the transparent substrate using, for example, a translucent color ink and a color filter, or by applying an adhesive sheet subjected to printing with a translucent color ink to the transparent substrate.

The thickness of the sheet capable of causing luminescence is preferably 5mm or less and more preferably 0.2 to 2 mm.

By allowing the above sheet capable of causing light emission to be subjected to a punching process, the low power consumption light emitting sheet of the present invention can be obtained.

Fig. 1 shows a cross-sectional view of a light-emitting sheet without perforations, which is obtained by providing a first electrode (transparent electrode) layer 2, a light-emitting layer 3, a dielectric layer 4, and a second electrode (back electrode) layer 5 on a transparent substrate 1. Fig. 2 shows a case where the punching process is performed from the second electrode (back electrode) layer 5 side.

The perforation process may be performed in such a manner that the holes have a desired shape and size. However, in order to obtain uniform light emission, it is preferable to perform the punching process in such a manner that holes having a uniform size are arranged in parallel at equal intervals in a matrix pattern, for example, a staggered pattern (60 °), a vertically staggered pattern, a parallel pattern, a staggered pattern of rectangular holes having circular corners, a parallel pattern of rectangular holes having circular corners, a staggered pattern of square holes, a parallel pattern of square holes, a staggered pattern of hexagonal holes (60 °), a staggered pattern of rectangular holes, or a parallel pattern of rectangular holes (see fig. 3 and 4).

Examples of the hole shape include, but are not particularly limited to, a circle, an ellipse, a triangle, a rectangle, a polygon, and a star. The diameter of the hole produced by the piercing process is not particularly limited; however, it is usually 0.1 to 20mm and preferably 0.5 to 10mm according to practical use. The interval length between the centers of the holes is usually 0.2 to 50mm, preferably 0.2 to 20mm, and further preferably 0.5 to 10 mm.

In order to prevent a reduction in brightness caused by the punching process and to achieve low power consumption, the aperture area ratio is preferably 5% to 80% and more preferably 10% to 60%. The term "pore area ratio" as used herein means the percentage (%) of the total area of pores over the area of the sheet. When the punching process is uniformly performed, the hole area ratio can be calculated by the following formula: [ (area of single hole x number of holes) × 100/area of sheet ].

Further, the hole shape, the hole diameter, the length of the interval between the hole centers, and the hole area ratio are selected as necessary. Thus, a light-emitting sheet having a reverse side to which a see-through effect (transparency) is imparted can be obtained.

Examples of the method of the punching treatment include, but are not particularly limited to, punchingProcessing, such as drilling, heated needle processing, punching, flat die cutting (punching with a flat blade), rotary die cutting (punching with a rotary blade); and the use of carbon dioxide (CO)₂) Laser, TEA-CO₂Laser, YAG laser, UV-YAG laser, excimer laser, semiconductor laser, YVO₄Laser processing with a laser, YLF laser, or picosecond laser.

When the power consumption of the non-perforated light emitting sheet is designated as 100%, the power consumption of the light emitting sheet of the present invention is generally in the range of 0% and 90% or less and preferably 30% to 90%.

When the brightness of the non-perforated light-emitting sheet is designated as 100%, the brightness of the light-emitting sheet of the present invention is generally 50% to 100% and preferably 70% to 100%. When the above-described luminance is 50% or more, sufficient visibility can be achieved.

The luminance (luminescence) according to the present invention can be obtained by the following formula: luminance (found value)) x [ sheet area- (single pore area × number of pores) ].

In the case where the light-emitting sheet of the present invention is used as an advertising medium, a decorative medium, or a warning board applied to a notice board or a show window of commercial buildings, vehicles, etc., such a light-emitting sheet may be protected by applying protective sheets on both sides of the light-emitting sheet. Such a protective adhesive sheet to be used is not particularly limited as long as it is transparent. Preferably, a scratch-resistant (hard coating) treatment is performed on such a protective sheet. Further preferably, such a protective sheet has a protection against gas (e.g., H)₂O or O₂) The performance of the barrier. When such protective sheets are attached to a wall or window, a variety of commercially available adhesives may be used.

Examples of the invention

The present invention is hereinafter described in more detail with reference to the following examples and comparative examples, although the technical scope of the present invention is not limited thereto.

In the following examples and comparative examples, a power consumption value, a power consumption ratio, luminance when light is emitted at 1W, luminosity, and an aperture area ratio were measured and calculated as described below.

[ measurement of Power consumption value and calculation of Power consumption ratio ]

Power consumption values of the unperforated luminescent sheet (comparative example) and the perforated luminescent sheet (example) were measured using Wat Checker (keishku Giken co., Ltd.).

Power consumption value is current (a) x voltage (V) x power factor

In addition, the ratio of the power consumption of the perforated light emitting sheet to the power consumption of the non-perforated light emitting sheet (comparative example 1) was designated as a power consumption ratio.

[ measurement of luminance and calculation of luminance and luminosity when light emission is performed with 1W of power consumption ]

The luminance of the non-hole portion of the non-perforated light emitting sheet (comparative example) and the luminance of the perforated light emitting sheet (example) were measured using a luminance meter LS-100 (MINOLTA).

Based on the above luminance (find value (cd/m)²) Luminance at the time of light emission) is obtained by the following formula:

luminance × [ (100-pore area ratio)/100 ]. Further, the luminance at the time of light emission calculated by the above formula is divided by the power consumption to calculate the luminance at the time of light emission per unit power consumption. The luminance (cd) is obtained by the following formula: [ lightness × [ sheet area- (single pore area × number of pores) ] ]

[ determination of the pore area ratio ]

Fig. 3 and 4 show how the hole area ratios resulting from different perforation treatment patterns are determined. In the following examples, the pore area ratio was determined according to the formula for the parallel pattern of square pores in fig. 4 (7). Further, in fig. 3 and 4, the letters "D", "P", "SP", "LP", "W", and "L" represent a circular hole diameter, pitch, square hole pitch (rectangular hole pitch (short)), rectangular hole pitch (long), hole width, and hole length (long), respectively. In FIGS. 3 and 4, the hole area ratio meter in each figureThe calculation formula is as follows: (1) staggered pattern:(2) vertical staggered pattern:(3) parallel pattern:(4) staggered pattern of rectangular holes with rounded corners:(5) parallel pattern of rectangular holes with rounded corners:(6) interlacing of square aperturesPattern formation:(7) parallel pattern of square holes:(8) staggered pattern of hexagonal holes (60 °):(9) staggered pattern of rectangular holes:(10) parallel pattern of rectangular holes:

[ example 1]

The invention is explained below with reference to fig. 1.

The first electrode (transparent electrode) layer 2(50nm thick) was formed by sputtering ITO on a 100 μm thick polyethylene terephthalate sheet (DIAFOILT-100, Mitsubishi Polyester Film Corporation) used as the transparent substrate 1. Subsequently, a ZnS: Cu solution (FEL-190, Fjikura Kasei Co., Ltd.) was applied to the ITO face of the first electrode layer 2, thereby forming a light-emitting layer 3 having a thickness of 50 μm and dried at 100 ℃ for 30 minutes using a dryer. Thereafter, a barium titanate solution (FEL-615, Fjikura Kasei co., Ltd) was further applied thereto, thereby forming the dielectric layer 4 to have a thickness of 50 μm. Drying was carried out using a desiccator at 100 ℃ for 30 minutes as described above. Thus, a sheet was obtained. Subsequently, a conductive paste (PEC-198, Fjikura Kasei co., Ltd) was applied to the above-described dielectric layer (barium titanate), thereby forming the second electrode (back electrode) layer 5 to have a thickness of 50 μm. For curing, the conductive paste was heated at 100 ℃ for 30 minutes using a dryer. An adhesive sheet (PET50(a) PL SHIN, lingec Corporation) was laminated thereto so as to obtain a sheet capable of causing luminescence.

CO was used in such a manner that holes having uniform hole sizes were arranged in parallel at equal intervals in a matrix pattern (hole shape: square (1 cm. times.1 cm); interval length between hole centers: 22.5 mm; and hole area ratio: 20%)₂The laser subjects the above-mentioned sheet (14cm × 25cm) capable of causing luminescence to a perforation treatment. Thus, the light emitting sheet is manufactured. The power consumption value of the light emitting sheet and the luminance at the time of light emission were measured at AC 100V of 50 Hz. Luminance of 306cd/m². In addition, the current was 0.08A, the voltage was 103.3V, and the power factor was 0.46.

[ example 2]

The piercing process was performed in the same manner as in example 1 except that the interval length between the centers of the holes was 18mm (hole area ratio: 30%) while keeping the hole diameter constant. Thus, the light emitting sheet is manufactured. The power consumption value of the light emitting sheet and the luminance at the time of light emission were measured at AC 100V of 50 Hz. Luminance is 339cd/m². In addition, the current was 0.07A, the voltage was 102.8V, and the power factor was 0.44.

[ example 3]

The piercing process was performed in the same manner as in example 1 except that the interval length between the centers of the holes was 14mm (hole area ratio: 50%) while keeping the hole diameter constant. Thus, the light emitting sheet is manufactured. The power consumption value of the light emitting sheet and the luminance at the time of light emission were measured at AC 100V of 50 Hz. Luminance is 399cd/m². In addition, the current was 0.04A, the voltage was 102.7V, and the power factor was 0.64。

[ example 4]

The piercing process was performed in the same manner as in example 1 except that the interval length between the centers of the holes was 12mm (hole area ratio: 70%) while keeping the hole diameter constant. Thus, the light emitting sheet is manufactured. The power consumption value of the light emitting sheet and the luminance at the time of light emission were measured at AC 100V of 50 Hz. Luminance is 462cd/m². In addition, the current was 0.02A, the voltage was 102.0V, and the power factor was 0.69.

Comparative example 1

The power consumption value and the luminance at the time of light emission of the non-perforated light emitting sheet were measured at AC 100V and 50 Hz. The resulting luminance was 245cd/m². In addition, the current was 0.11A, the voltage was 103.1V, and the power factor was 0.38.

Table 1 shows these results.

[ Table 1]

	Aperture area ratio (%)	Power consumption (W)	Ratio of Power consumption (%)	Luminance (cd/m)2)	Luminance when light emission is performed with 1W power consumption	Luminosity (cd)
							Example 1	20	3.8	88	306	64.4	8.57
Example 2	30	3.2	74	339	74.2	8.31
							Example 3	50	2.6	60	399	76.7	7.00
Example 4	70	1.4	33	462	99.0	4.85
							Comparative example 1	0	4.3	100	245	57.0	8.57

Based on the results shown in table 1, it was confirmed that the punching process reduced the power consumption of the light emitting sheet. In addition, in each example, the luminance obtained when light is emitted with 1W power consumption is higher than that obtained in the case of the light emitting sheet of comparative example 1. Further, even with an increased aperture area ratio, the luminance reduction ratio is significantly reduced. Thus, the light emitting sheet of the present invention is confirmed to have excellent performance so as to be used as a low power consumption light emitting sheet.

Industrial applicability

The luminescent sheet of the present invention may be used in a variety of fields relating to advertising media, decorative media, warning boards, lighting applications, backlighting applications, and the like.

Claims (7)

1. A light-emitting sheet obtained by allowing a sheet capable of causing light emission to be subjected to a punching process.

2. A light-emitting sheet according to claim 1, wherein the sheet capable of causing light emission is an electroluminescent sheet.

3. The luminescent sheet according to claim 1, wherein the aperture area ratio is 5% to 80%.

4. The light-emitting sheet according to claim 1, wherein the hole diameter at the time of the perforation process is 0.1 to 20mm and the interval length between the hole centers is 0.2 to 50 mm.

5. The luminescent sheet according to claim 1, which is subjected to a perforation treatment in a matrix pattern.

6. The method for producing a light-emitting sheet according to claim 1, comprising allowing a sheet capable of causing light emission to be subjected to a perforation treatment.

7. A method according to claim 6, wherein the perforation process is carried out by drilling, heated needle processing, punching, flat die cutting, rotary die cutting or laser processing.