JP6746908B2 - See-through type LED display device and LED display system using the same - Google Patents

Description

The present invention relates to a see-through type LED display device and an LED display system using the same.

Various LED display devices represented by a dot-matrix display device that displays information by forming desired characters, symbols, or patterns by selectively emitting light from LED elements mounted in a matrix form has become popular. I'm out. In the LED dot matrix display device, the light emitted from the LED elements is directly recognized as the above-mentioned two-dimensional array, so that higher brightness and higher contrast are realized as compared with the display using liquid crystal or the like. It's easy to do. Further, it is also advantageous in that high visibility is easily obtained even when ambient light is radiated on the display surface of the display device. As such an LED dot matrix display device, for example, an LED display panel in which a display window is formed on a surface of a housing accommodating electronic parts and a plurality of LED elements are arranged in a matrix on a wiring board is provided. There is known an LED display device or the like configured to control the display of the LED elements of this LED display panel (see Patent Document 1).

Here, it is assumed that the LED display device described in Patent Document 1 is a display device having a function of transmitting visual information to a person located on the front surface side of the display device, that is, the light emitting surface side of the LED element. Is designed to.

However, with the widespread use of LED display devices in recent years, a person located on the front side of the LED display device can see all the characters, figures, other exhibits, etc. located on the back side of the LED display device. A see-through type LED display device capable of visually recognizing visual information has been demanded.

In an LED display device, a circuit board for an LED element on which an LED element is mounted usually includes a wiring portion, an insulating protective film, and the like, and a portion that is generally colored and poor in visible light transmission is an essential component. It exists in a certain ratio or more with respect to the surface area of the substrate. Therefore, in order to make it a “see-through type”, it is necessary to specially devise the layer structure of the LED element substrate.

For example, an LED display panel designed to emit light from an LED element toward both sides, in which a wiring portion is formed of transparent electrodes, has been developed (see Patent Document 2). By applying the layer structure of the double-sided light emitting type LED display device, it is possible to avoid the wiring portion from obstructing the light transmissivity necessary for ensuring the see-through function.

JP, 2006-145682, A JP, 2009-239235, A

As described in Patent Document 1, in an LED dot matrix display device, light is normally shielded above a light emitting surface side of light emitted from an LED element, leaving a translucent hole formed in accordance with the arrangement of the LED elements. A contrast-enhancing dark layer is disposed. The contrast-enhancing dark color layer darkens the surroundings of the LED element, which is a light-emitting body, to improve the substantial luminance of the light-emitting body during lighting, and further, the luminance during lighting and the darkness during non-lighting. It is arranged for the purpose of increasing the difference from the brightness and improving the contrast in the screen display of the LED dot matrix display device.

In the case of a see-through type LED display device, it is necessary to make the LED element substrate a translucent substrate so that visual information on the back side of the LED display device can be visually recognized from the front side of the LED display device. There is. However, as in the LED display device described in Patent Document 1, a configuration is such that a display window is formed on the housing surface so that high visibility is obtained, and a contrast-improving dark color layer that shields light by leaving a light-transmitting hole is arranged. Therefore, the substrate for the LED element cannot be a substrate having a light-transmitting property.

Further, in the case of the see-through type LED display device, the visibility of the information displayed on the LED display device is further deteriorated by the external light from the back side of the LED display device as compared with the normal LED display device. Therefore, even in the case of a see-through type LED display device, it is required to develop a flexible transparent substrate for the see-through type LED display, which has high visibility of information displayed on the LED display device.

The present invention has been made to solve the above problems, and an object of the present invention is to provide a see-through LED having high visibility of information displayed on the LED display even in the case of a see-through LED display. It is to provide a display device.

As a result of intensive studies, the inventors of the present invention have found that, in a plan view of a flexible transparent substrate on a supporting substrate of a flexible transparent substrate, a contrast-improving dark color portion is provided near the outer edge of the LED element and/or near the inner edge of the LED element. The inventors have found that a see-through type LED display device in which is arranged can solve the above problems, and have completed the present invention.

(1) A see-through type LED display device in which LED elements are mounted on a flexible transparent substrate, wherein the flexible transparent substrate has flexibility, and a haze value measured according to JIS-K7136. Of 20% or less, a wiring portion laminated on the surface of the supporting substrate via an adhesive layer, and a region excluding the mounting region of the LED element, the supporting substrate and the wiring portion. An insulating protective film, which is laminated on the insulating film and has a haze value of 20% or less measured according to JIS-K7136, and in the plan view of the LED display device, in the vicinity of the outer end of the LED element. And/or a contrast-improving dark color portion is arranged near the inner edge of the LED element, and the contrast-improving dark color portion is measured in accordance with JIS-Z8722 according to D65 light source, 10° viewing angle condition ΔL ^*. A see-through type LED display device having a value of 60 or less.

According to the invention of (1), it is possible to avoid a reduction in the visibility of information displayed on the LED display device due to the flexible transparent substrate for see-through type LED display.

(2) The shape of the opening of the contrast-enhancing dark color part is such that the inner diameter of the opening is reduced from the display surface side of the LED display device toward the surface opposite to the display surface side (1). LED display device according to.

According to the invention of (2), in addition to the effect of the invention of (1), it is possible to avoid blocking of light from the LED element by the contrast-enhancing dark color portion, and avoid deterioration of optical characteristics of the LED display device.

(3) The LED display device according to (1) or (2), wherein the coverage of the wiring portion on the support substrate is 2% or more and 10% or less.

According to the invention of (3), in addition to the effect of the invention of (1) or (2), the see-through type in which the visibility of the visual information on the back side is high by specifying the coverage of the wiring portion on the supporting substrate LED display device.

(4) A multi-layer display surface type LED display system, further comprising a rear side display device for displaying visual information on the rear side of the LED display device according to any one of (1) to (3).

According to the invention of (4), in addition to the effects of the inventions of (1) to (3), a person located on the front side of the LED display device recognizes the information displayed on the LED display device at the same time. The visual information on the back side of the LED display device can be visually recognized.

The see-through type LED display device of the present invention is a see-through type LED display device capable of avoiding deterioration of visibility of information displayed on the see-through type LED display device.

It is a partial enlarged plan view of the front side of a see-through type LED display device in which an LED element is mounted on a flexible transparent substrate of the present invention. It is sectional drawing showing the cross section of the AA part of FIG. 1, and is a drawing with which explanation of one mounting mode of the LED display device of this invention is provided. It is sectional drawing showing the cross section of the AA part of FIG. 1, and is drawing used for description of the other mounting aspect of the LED display apparatus of this invention. It is a front view of a see-through type LED display device of the present invention. It is a front view showing an example of an embodiment of a see-through type LED display device of the present invention.

Hereinafter, the details of the see-through type LED display device of the present invention will be sequentially described with reference to the embodiments. The present invention is not limited to the following embodiments and can be implemented with appropriate modifications within the scope of the object of the present invention.

<LED display device>
[overall structure]
As shown in FIG. 2, the LED display device 1 of the present embodiment is a see-through type LED display device in which LED elements are mounted on a flexible transparent substrate.

As shown in FIG. 2, in the see-through type LED display device 1 of the present embodiment, the wiring portion 13 is laminated on the surface of the support substrate 11 preferably made of a thermoplastic resin with the adhesive layer 12 interposed therebetween. Then, as shown in FIG. 2, in order to improve the migration resistance of the flexible transparent substrate, an insulating protective film 15 is laminated on the support substrate 11 and the wiring portion 13 so as to cover a region other than the mounting region a of the LED element 2. ing.

Here, the insulating protective film 15 is laminated on the support substrate 11 on the surface of the support substrate 11 via the adhesive layer 12. The adhesive layer 12 remains on the support substrate 11 after the wiring portion 13 is etched. In the present invention, the adhesive layer 12 is not essential, and the wiring portion 13 may be directly laminated on the support substrate 11 by depositing a metal foil, for example. Here, as shown in FIG. 2 and FIG. 3, the mounting area of the LED element 2 is a joint portion of the LED element 2 to the wiring portion 13 and a peripheral portion thereof, where light emitted from the LED element 2 is emitted. The space required as a path for reaching the outside of the flexible transparent substrate 10. In FIG. 2, the insulating protective film 15 is arranged so that the position of the LED element mounting through-hole 151 of the insulating protective film 15 overlaps with the LED element mounting region.

The flexible transparent substrate 10 according to this embodiment is a wiring substrate having “translucency”. However, it is not always necessary that the whole is completely transparent, and it is sufficient if the wiring substrate has at least 60% or more of its surface having “translucency”. In the present specification, “having a light-transmitting property” means colorless and transparent or colored semi-transparent through visual information located on the back side of the transparent or translucent film or sheet. Means that it is visible under the desired use environment. In addition to the haze value of the light transmissive portion, the light transmittance of the portion in the visible light region is about 80% or more. The light transmittance of the flexible transparent substrate 10 in the visible light region, that is, the visible light transmittance can be measured by a method according to JIS R3212.

Further, on the LED display device 1 of the embodiment of FIG. 2, the contrast improving dark color portion 14 is arranged near the outer side of the end of the LED element in the plan view of the LED display device 1. The contrast improving dark color portion 14 can be formed of, for example, a resin base material containing a black pigment or a dark color pigment. The vicinity of the outside of the end of the LED element means a peripheral portion of the LED element 2 and a region close to the end 21 of the LED element, such as the area where the contrast improving dark color portion 14 is arranged in FIG. ..

An LED display device 1a of FIG. 3, which is another embodiment of the present invention, will be described. On the LED display device 1a of the embodiment of FIG. 3, the contrast improving dark color portion 14 is disposed near the inner side of the end on the LED element in the plan view of the LED display device 1a. The vicinity of the inside of the end on the LED element is an area above the LED element 2a and inside from the end 21a of the LED element, as in the area where the contrast improving dark portion 14a is arranged in FIG. , An area close to the end 21a of the LED element.

Here, in the conventional general see-through type LED display device, as described above, external light passes from the back side of the LED display device, and thus the visibility of the information displayed on the LED display device deteriorates. It is extremely difficult to completely prevent this, because of the structure of the see-through type LED display device that allows light to pass through.

On the other hand, in the see-through type LED display device 1 (1a) of the embodiment of FIGS. 2 and 3, the LED display device having a translucency as an essential property for maintaining the property of the see-through type LED display. At the same time, the contrast-improving dark color portion 14 (14a) is arranged in the vicinity of the outer edge of the LED element and/or in the vicinity of the inner edge of the LED element, thereby impairing the original translucency of the see-through type LED display device. Instead, the see-through type LED display device 1 has high visibility of information displayed on the LED display device.

By arranging the contrast-enhancing dark color portion 14 (14a) near the outside of the edge of the LED element and/or near the inside of the edge of the LED element, the contrast-enhancing dark color portion 14 causes the contrast-enhancing dark color portion 14 when viewed from the front side of the LED display device. The outer periphery of the LED element 2 is visually recognized as a dark color (see FIGS. 1 and 4). Therefore, the see-through type LED display device 1 of the present embodiment can realize the same contrast as that of the conventional LED display device.

The contrast-enhancing dark-colored portion according to the present invention may be arranged in either or both of the vicinity of the outside of the end of the LED element and the vicinity of the inside of the end on the LED element. The vicinity of the outside of the end of the LED element refers to an area within 5 mm from the end 21 (21a) of the LED element to the outside, and the vicinity of the inside of the end on the LED element is within 2 mm from the end 21 (21a) of the LED element to the inside. Area. As in the LED display device 1 of the embodiment shown in FIG. 2, the contrast improving dark color portion 14 is arranged near the outer edge of the LED element of the LED element 2 so that high contrast is realized and light from the LED element 2 is realized. However, it is possible to display information by the LED element on the display surface of the LED display device 1 in a state in which the light shielding by the contrast improving dark color portion 14 is reduced. In FIG. 2, the width L1 in which the contrast-enhancing dark color portion 14 is disposed near the outer edge of the LED element is 0.2 mm or more and 4 mm or less, and more preferably 0.5 mm or more and 2 mm or less. It is preferable that the contrast-enhancing dark color portion 14 is disposed at the position.

Further, by providing the contrast improving dark color portion 14a near the inner end of the LED element as in the LED display device 1a of the embodiment of FIG. 3, while achieving high contrast, the contrast improving dark color portion 14a allows see-through. The translucency from the back side of the LED display device 1a of the mold is not impaired, and the visibility of the visual information located on the back side of the LED display device 1a can be made more preferable. In FIG. 3, the width L2 in which the contrast-improving dark color portion 14a is arranged near the inner end of the LED element is 0.2 mm or more and 2 mm or less, more preferably 0.5 mm or more and 1.5 mm or less. It is preferable that the contrast-improving dark color portion 14a is arranged so that

Regarding the tint of the contrast enhancing dark color portion 14, more specifically, ΔL ^* of the contrast enhancing dark color portion under the condition of D65 light source and 10° viewing angle is 60 or less, preferably in accordance with JIS-Z8722. It is 10 or less. By setting the range of ΔL ^* of the contrast improving dark color portion 14 to this range, high contrast can be realized and the visibility of the see-through type LED display device 10 can be improved as described above. According to JIS-Z8722, the ΔL ^* value measured under the conditions of a D65 light source and a 10° viewing angle can be measured using, for example, a spectrocolorimeter CM-700d (manufactured by KONICA MINOLTA).

The see-through type LED display device of the present invention adjusts the visibility of the information by the LED element and the visibility of the visual information located on the back side of the LED display device by adjusting the arrangement of the contrast enhancing dark color portion 14. be able to.

Further, in order to reduce the blocking of light from the LED element by the contrast improving dark color portion and avoid the deterioration of the optical characteristics of the LED display device, the shape of the opening of the contrast improving dark color portion is the display surface side of the LED display device. The shape is preferably such that the inner diameter of the opening is reduced from the opposite side to the display surface side. The shape in which the inner diameter of the opening is reduced is a so-called reverse taper side wall shape. The "inverted taper side wall shape" means the display surface side (the surface of the contrast improving dark color portion 14 of the LED display device in which the opening is formed, like the shape of the opening 141 (141a) shown in FIG. 2 or FIG. It is a shape in which the hole diameter of the opening is reduced from the opening side) toward the opposite side of the display surface side (the rear opening side of the contrast improving dark color portion 14). Note that, as shown in FIG. 2 or 3, it is more preferable that the reduction of the hole diameter is linear, and the surface shape of the wall forming the opening is substantially flat. This is because the pressing die used to form the reverse tapered side wall shape can be easily processed, and more precise processing can be performed.

As in the LED display device 1 of FIG. 2, the contrast improving dark color portion 14 in which the contrast improving dark color portion is arranged near the outer side of the end of the LED element and the shape of the opening portion 141 is a reverse taper side wall shape. Light shielding of the contrast improving dark color portion 14 can be reduced as compared with the contrast improving dark color portion which is not in the shape of an inverted taper side wall.

Even when the contrast improving dark color portion is arranged near the inner end of the LED element as in the LED display device 1a of FIG. 3, the shape of the opening 141a is a reverse tapered side wall shape. If it is a portion, it is possible to reduce the light shielding of the contrast improving dark color portion 14 as compared with the contrast improving dark color portion in which the shape of the opening 141 is not a reverse tapered side wall shape.

[Supporting substrate]
First, the supporting substrate 11 that constitutes the see-through type LED display device 1 of the present embodiment is required to be a film or sheet having the flexibility and the light transmitting property of the flexible transparent substrate 10. For example, the support substrate 11 is a resin film having a haze value of 20% or less, preferably 10% or less. Further, “having a light-transmitting property” means that the visual information located on the back side of the transparent or semi-transparent film or sheet that is colorless and transparent or colored is desired. It means that it is visible under the environment of use. In addition to the above-mentioned haze value, the light transmittance in the visible light region is about 80% or more. Although the thickness of the support substrate 11 is not particularly limited, the flexible transparent substrate 10 may be provided with translucency and flexibility as long as the heat resistance and insulation properties of the flexible transparent substrate 10 can be ensured. From the viewpoint of cost reduction, it is generally preferable that the thickness is as thin as possible. Specifically, it is preferably about 10 μm or more and 100 μm or less. Further, the thickness is preferably within the above range from the viewpoint of maintaining good productivity when the roll-to-roll method is used.

The resin used as the material of the support substrate 11 is required to have high heat resistance. Specifically, it is preferable that the resin has a heat shrinkage initiation temperature of 100° C. or higher, or a resin whose heat resistance is improved by annealing treatment so that the temperature becomes 100° C. or higher. Usually, the heat generated from the LED element causes the temperature around the element to reach about 90°C. In addition, for example, when forming a thermosetting insulating protective film, it is assumed that the heating temperature for thermosetting may reach up to about 100°C. From both of the above viewpoints, it is preferable that the resin forming the support substrate 11 has heat resistance equal to or higher than the above temperature. In the present specification, the "heat shrinkage start temperature" means that a sample film made of a thermoplastic resin to be measured is set in a TMA device, a load of 1 g is applied, and the temperature is increased to 120°C at a temperature rising rate of 2°C/min. Warm up, measure the amount of shrinkage at that time (% display), output this data and read the temperature and the amount of shrinkage recorded from the graph, read the temperature away from the 0% baseline due to shrinkage, and then perform the heat shrinkage This is the starting temperature.

The supporting substrate 11 is required to be a resin that can provide the insulating property required for the flexible transparent substrate 10. Generally, the support substrate 11 has a volume resistivity (measured in accordance with JIS C6481) (in this specification, "volume resistivity" means this value) of 10 ¹⁴ Ω. It is preferably at least 10 cm and more preferably at least 10 ¹⁸ Ω·cm. The volume resistivity can be measured, for example, by using a digital ultra-high resistance/micro ammeter 5450/5451 manufactured by ADC.

As described above, as preferable examples of the resin used as the supporting substrate 11 required to satisfy the requirements such as flexibility and transparency, heat resistance, insulation, light resistance and weather resistance, polyimide (PI), polyethylene naphthalate ( PEN), polyethylene terephthalate (PET), amorphous polyarylate, polysulfone, polyether sulfone, polyetherimide, fluororesin, liquid crystal polymer and the like can be mentioned. Among them, polyethylene naphthalate (PEN), which has improved heat resistance and dimensional stability by performing heat resistance improvement treatment such as annealing treatment, can be particularly preferably used.

[Contrast enhancement dark part]
The contrast-enhancing dark color portion 14 according to the present embodiment is supported on the support substrate 11 in the vicinity of the outer edge of the LED element for the purpose of improving the visibility of the information displayed by the see-through type LED display device 10. It is arranged directly on the surface of the substrate 11 or via another functional layer.

The contrast improving dark color portion 14 may be a blackened or darkened insulating protection layer (not shown) arranged to improve the migration resistance of the flexible transparent substrate 10.

The contrast improving dark color portion 14 can be formed by, for example, a so-called in-mold for forming the contrast improving dark color portion 14 by closing the LED display device in a mold and supplying blackened or darkened injection resin. When the contrast-enhancing dark color portion is formed as the contrast-enhancing dark color layer, it may be formed by an insulating thermosetting ink to which an appropriate amount of black or dark pigment is added.

As the black or dark color pigment, various conventionally known pigments can be widely used as long as they can form the contrast-improving dark color portion satisfying the above-mentioned insulating property and tint. For example, an inorganic pigment such as carbon black or titanium pigment subjected to insulation strengthening treatment, or oxazine-based, pyrrole-based, quinacridone-based, azo-based, perylene-based, dioxane-based, isoindolinone-based, induslen-based, Dark-colored organic pigments such as quinophthalone type, perinone type, and phthalocyanine type can be used. Further, a pigment obtained by mixing two or more kinds of these pigments can also be used in the same manner as long as it satisfies the above-mentioned insulating property and tint.

Further, as a dark organic pigment, a benzimidazolone pigment, 4-[(2,5-dichlorophenyl)azo]-3-hydroxy-N-(2,5-dimethoxyphenyl)-2-naphthalenecarboxamide, 1-[ (4-Nitrophenyl)azo]-2-naphthalenol, bis[3-hydroxy-4-(phenylazo)-2-naphthalenecarboxylic acid] copper salt, N,N′-bis(2,4-dinitrophenyl)-3 ,3'-dimethoxy-1,1'-biphenyl-4,4'-diamine, 3,4,9,10-perylenetetracarboxylic acid diimide, Δ2,2'(1H,1'H)-binaphtho[2. 1-b] thiophene-1,1'-dione and N,N'-(10,15,16,17-tetrahydro-5,10,15,17-tetraoxo-5H-dinaphtho[2,3-a:2 A pigment containing at least one brown pigment selected from the group consisting of',3'-i]carbazole-4,9-diyl)bis(benzamide) and a phthalocyanine pigment is particularly preferable. By using a brown pigment and a phthalocyanine pigment instead of a black pigment such as carbon black, absorption of infrared light is suppressed, so that heat generation due to absorption of infrared light can be suppressed. Furthermore, by using a brown pigment and a phthalocyanine pigment, even if the thickness of the contrast-improving dark color portion 14 is reduced, the contrast-improving dark color portion 14 has a black color and can realize high contrast. .. Therefore, it is preferable to use a pigment containing a brown pigment and a phthalocyanine pigment from the viewpoint of productivity. The brown-based pigment is preferably a benzimidazolone-based pigment from the viewpoints of dispersibility of the pigment in the contrast-enhancing dark color portion 14 and adhesiveness between the contrast-enhancing dark color portion 14 and other layers.

In the present specification, brown pigments include benzimidazolone pigments, 4-[(2,5-dichlorophenyl)azo]-3-hydroxy-N-(2,5-dimethoxyphenyl)-2-naphthalenecarboxamide. , 1-[(4-nitrophenyl)azo]-2-naphthalenol, bis[3-hydroxy-4-(phenylazo)-2-naphthalenecarboxylic acid] copper salt, C.I. I. Pigment Brown7, N,N'-bis(2,4-dinitrophenyl)-3,3'-dimethoxy-1,1'-biphenyl-4,4'-diamine, 3,4,9,10-perylenetetracarboxylic acid Diimide, Δ2,2′(1H,1′H)-binaphtho[2,1-b]thiophene-1,1′-dione and N,N′-(10,15,16,17-tetrahydro-5,10. ,15,17-Tetraoxo-5H-dinaphtho[2,3-a:2',3'-i]carbazole-4,9-diyl)bis(benzamide) Refers to pigments. The benzimidazolone pigment is a pigment having a benzimidazolone skeleton represented by the following general formula (1). Specifically, PigmentYellow120, PigmentYellow151, PigmentYellow154, PigmentYellow175, PigmentYellow180, PigmentYellow181, PigmentYellow194, Pigment Red175, PigmentRed176, PigmentRed185, PigmentRed208, Pigment Violet32, PigmentOrange36, PigmentOrange62, PigmentOrange72, but PigmentBrown25 etc., not limited thereto .. From the viewpoint of color gamut, C.I. I. Pigment Brown 25 is more preferable.

The primary particle size of the benzimidazolone pigment is preferably 0.01 μm or more and 0.20 μm or less. By setting the primary particle diameter of the benzimidazolone pigment in such a range, the dispersibility of the pigment in the contrast-enhancing dark color portion 14 can be improved.

4-[(2,5-dichlorophenyl)azo]-3-hydroxy-N-(2,5-dimethoxyphenyl)-2-naphthalenecarboxamide is specifically C.I. I. Pigment Brown 1 and the like. 1-[(4-nitrophenyl)azo]-2-naphthalenol is specifically C.I. I. Pigment Brown 2 and the like. The bis[3-hydroxy-4-(phenylazo)-2-naphthalenecarboxylic acid] copper salt specifically includes C.I. I. Pigment Brown 5 and the like. N,N'-bis(2,4-dinitrophenyl)-3,3'-dimethoxy-1,1'-biphenyl-4,4'-diamine is specifically C.I. I. Pigment Brown 22 and the like. Specific examples of 3,4,9,10-perylenetetracarboxylic acid diimide include C.I. I. Pigment Brown 26 and the like. Δ2,2′(1H,1′H)-binaphtho[2,1-b]thiophene-1,1′-dione refers specifically to C.I. I. Pigment Brown 27 and the like. N,N'-(10,15,16,17-tetrahydro-5,10,15,17-tetraoxo-5H-dinaphtho[2,3-a:2',3'-i]carbazole-4,9- Diyl)bis(benzamide) means specifically C.I. I. Pigment Brown 28 and the like. In addition to the above brown pigments, C.I. I. Pigment Brown 7 may be used.

The phthalocyanine-based pigment is a pigment having a phthalocyanine skeleton, and is a concept that also includes phthalocyanine to which various metals are coordinated. Specifically, C.I. I. PigmentGreen7, C.I. I. Pigment Green 36, C.I. I. PigmentGreen37, C.I. I. Pigment Blue 16, C.I. I. Pigment Blue 75, or C.I. I. Pigment Blue 15 and the like, but the present invention is not limited to this. It is preferable to use an amorphous phthalocyanine pigment that is a blue pigment.

The primary particle size of the phthalocyanine-based pigment is preferably 0.15 μm or more and 0.20 μm or less. With such a range, the dispersibility of the pigment in the contrast improving dark color portion 14 can be improved.

The content of the brown pigment in the contrast improving dark color portion 14 is 43 parts by mass or more and 233 parts by mass or less with respect to 100 parts by mass of the phthalocyanine pigment (the content ratio of the brown pigment and the phthalocyanine pigment is a mass ratio). 30:70 to 70:30), and 66 parts by mass or more and 150 parts by mass or less (the content ratio of the brown pigment and the phthalocyanine pigment is 40:60 to 60:40 by mass ratio). It is more preferable to set the range). By setting the content ratio in such a range, the hiding property of the contrast improving dark color portion 14 can be made preferable.

The content of the pigment in the contrast-enhancing dark color portion 14 can be specified by the transmittance of light having a specific wavelength in the light transmittance test. Further, in order to make the content of the brown pigment such as benzimidazolone pigment and the content of the phthalocyanine pigment preferable in terms of realizing high contrast and infrared transparency, the contrast improving dark color portion 14 should be provided. A brown pigment such as a benzimidazolone pigment and a phthalocyanine pigment contained therein are 80% by mass or more in the total amount of the pigment components, and the transmittance of light having a wavelength of 450 nm in the light transmittance test in the contrast improving dark color portion 14 Is 5% or more and 27% or less, and the transmittance of light having a wavelength of 700 nm is preferably 3% or more and 20% or less. The phthalocyanine-based pigment has a property of transmitting a certain amount of light having a wavelength of 450 nm and not transmitting light having a wavelength of 700 nm. A brown pigment such as a benzimidazolone pigment has a property of transmitting a certain amount of light having a wavelength of 700 nm and a property of not transmitting light having a wavelength of 450 nm. Therefore, by specifying the transmittance of light having a wavelength of 450 nm and the transmittance of light having a wavelength of 700 nm in the light transmittance test, the content of brown pigments such as benzimidazolone pigments and the content of phthalocyanine pigments can be determined. The content ratio with respect to the amount can be specified.

The method for measuring the transmittance of the contrast-enhancing dark color portion 14 is, for example, gravure-coating an infrared-transmissive dark ink containing the above-mentioned pigment and a curing agent on white PET, laminating polyethylene thereon, and at least 45° C. An infrared reflection sheet is prepared by aging treatment at 55° C. or less for 168 hours and curing by heating, and light having a wavelength of 300 nm to 1200 nm is measured by a spectrophotometer (“U-4100” manufactured by Hitachi High-Technologies Corporation). The reflectance can be measured by measuring the reflectance (%) and determining the transmittances of light having a wavelength of 450 nm and light having a wavelength of 700 nm, respectively.

The pigment containing the brown pigment and the phthalocyanine pigment is preferably 20 parts by mass or more and 50 parts by mass or less, and 35 parts by mass of the mixed pigment with respect to 100 parts by mass of the resin component in the contrast improving dark part 14. It is more preferable that the amount is not less than 45 parts by mass. By setting the content of the mixed pigment within this range, the color tone of the contrast improving dark color portion 14 can be stabilized.

An inorganic black pigment may be supplementarily added to the contrast improving dark color portion 14 in a ratio within a predetermined range to adjust the black tint to a desired tint. Carbon black is a typical example of an inorganic black pigment. The inorganic black pigment may be added in a range of 3% by mass or more and 50% by mass or less based on the mass ratio of the base resin. When the addition amount is within this range, the appearance of the contrast-enhancing dark color portion 14 can be appropriately adjusted to an optimum tint while maintaining other desirable physical properties of the contrast-enhancing dark color portion 14 in the present invention.

As the thermosetting resin that forms the contrast-enhancing dark color portion 14, a known thermosetting resin can be appropriately used as long as the thermosetting temperature is about 100° C. or lower. Specifically, a thermosetting resin having a polyester resin, an epoxy resin, an epoxy resin, a phenol resin, an epoxy acrylate resin, a silicone resin, or the like as a base resin can be preferably used. Among these, the polyester thermosetting resin is particularly preferable as the material for forming the contrast-improving dark color portion 14 of the see-through type LED display device 1 because of its excellent flexibility.

Regarding the tint of the contrast-enhancing dark color portion 14, it is preferable that the ΔL ^* value measured according to JIS-Z8722 under the conditions of D65 light source and 10° viewing angle is 60 or less, preferably 10 or less. By setting the ΔL ^* value of the contrast improving dark color portion 14 in the above range, the tint of the contrast improving dark color portion 14 can be sufficiently black or dark, and the visibility of the display information can be sufficiently improved by the improvement of the contrast. .. Further, since the ΔL ^* value of the contrast-enhancing dark color portion 14 is 60 or less, it is possible to prevent the difficulty in adjusting the brightness of the display of the LED display device 10 due to the diffuse reflection of visible light in the same layer. .. According to JIS-Z8722, the ΔL ^* value measured under the conditions of a D65 light source and a 10° viewing angle can be measured using, for example, a spectrocolorimeter CM-700d (manufactured by KONICA MINOLTA).

[Adhesive layer]
The adhesive layer 12 is not essential in the present invention, but the wiring portion 13 on the surface of the flexible transparent substrate 10 can be formed by, for example, a dry laminating method via the adhesive layer 12. The adhesive forming the adhesive layer 12 contains a main resin, a curing agent and a solvent, and also contains various other additives as required. As other additives, an adhesion auxiliary agent and the like can be mentioned as an example. The adhesive is preferably a two-component type in which the main resin and the curing agent are mixed immediately before use. When forming the adhesive layer, the base resin reacts with the curing agent and is crosslinked to have a high molecular weight. Urethane-based, acrylic-based, and epoxy-based resins can be appropriately selected as the main material resin. Among these main material resins, from the viewpoint of mechanical properties and electrical properties, a urethane-based adhesive having excellent flexibility and insulating properties can be preferably used as the adhesive forming the adhesive layer 12. Among the above adhesives, an acrylic adhesive having excellent transparency can be preferably used as the adhesive forming the adhesive layer 12 from the viewpoint of optical characteristics. Depending on the usage environment of the flexible transparent substrate 10, an epoxy adhesive having excellent heat resistance and chemical resistance can also be preferably used.

[Wiring part]
As shown in FIG. 1, the wiring portion 13 is a wiring pattern formed on the surface of the flexible transparent substrate 10 by a conductive base material such as a metal foil. The wiring portion 13 has a function of, for example, conducting between 1000 or more LED elements 2 and supplying a necessary current to supply electricity, and also functions as a heat radiation portion in the flexible transparent substrate 10. Is.

The thermal conductivity λ of the material forming the wiring portion 13 is preferably 200 W/(m·K) or more and 500 W/(m·K) or less, and more preferably 300 W/(m·K) or more and 500 W/(m·K) or less. preferable.

The electrical resistivity R of the wiring forming the wiring portion 13 is preferably 3.00×10 ⁻⁸ Ωm or less, and more preferably 2.50×10 ⁻⁸ Ωm or less. Here, the thermal conductivity λ can be measured, for example, by using a thermal conductivity meter QTM-500 manufactured by Kyoto Electronics Manufacturing Co., Ltd., and the electrical resistivity R can be measured, for example, by Keithley Model 6517B electrometer. Can be used. According to this, for example, in the case of copper, the thermal conductivity λ is 403 W/(m·K) and the electrical resistivity R is 1.55×10 ⁻⁸ Ωm. As a result, variations in light emission between the LED elements are reduced, stable light emission is possible as a whole of the see-through type LED display device, and the life of the LED elements is extended.

The layout of the wiring portion 13 is not limited to a specific layout or the like as long as the LED element 2 can be mounted. However, the LED display device 1 may be arranged such that the ratio of the portion of the one surface of the support substrate 11 covered by the wiring portion 13, that is, the substrate coverage by the wiring portion is 40% or less. preferable. Further, it is more preferable that the coverage of the wiring portion 13 on the support substrate 11 is 2% or more and 10% or less.

Examples of the material forming the wiring portion 13 include metal foils such as aluminum, gold, silver, and copper. The thickness of the wiring portion 13 may be appropriately set according to the withstand current and the like required for the flexible transparent substrate 10, and is not particularly limited, but an example is a thickness of 10 μm or more and 50 μm or less. From the viewpoint of improving heat dissipation, the thickness of the wiring portion 13 is preferably 10 μm or more. If the thickness of the metal layer is less than the above lower limit, the effect of thermal contraction of the support substrate 11 is large, and the warp after the solder reflow treatment is likely to be large. It is preferably 10 μm or more. On the other hand, when the thickness is 50 μm or less, it is possible to maintain sufficient flexibility of the flexible transparent substrate 10 and prevent deterioration of handling property due to increase in weight.

In order to make the LED display device transparent so that visual information on the back side of the LED display device can be visually recognized from the front side of the LED display device, indium tin oxide (ITO) is used as a material for forming the wiring portion. Conductive oxides such as indium zinc oxide (IZO), tin oxide, zinc oxide, indium oxide, aluminum zinc oxide (AZO), metals such as nickel, and conductivity such as polyaniline, polyacetylene, polyalkylthiophene derivatives, and polysilane derivatives. It is also possible to use a conductive material capable of forming a transparent electrode such as a polymer, carbon nanotube or graphene.

[Insulation protection film]
The insulating protective film 15 is mainly formed on the surface of the wiring substrate 13 and the supporting substrate 11 except for a portion where electrical bonding is required by a thermosetting ink or an ultraviolet curable ink, and is mainly formed on the flexible transparent substrate 10. Stacked to improve migration characteristics. Like the support substrate 11, the insulating protective film 15 is required to be able to maintain the flexibility and translucency of the flexible transparent substrate 10. The haze value and other optical characteristics specifically required for the insulating protective film 15 are similar to the same characteristics required for the support substrate 11, and the haze value is 20% or less, preferably 10% or less.

A thermosetting ink can be preferably used as the insulating ink for forming the insulating protective film 15. As the thermosetting ink, a known ink can be appropriately used as long as the thermosetting temperature is about 100° C. or lower. Specifically, it is possible to use an insulating ink which is a urethane-based, acrylic-based, or epoxy-based resin and whose main resin is the same resin as the main resin of the adhesive forming the adhesive layer 12. it can. Among these, urethane-based thermosetting insulating ink can be preferably used as a material for forming the insulating protective film 15 of the flexible transparent substrate 10 because of its excellent flexibility and insulating property. ..

[Other functional layers]
The flexible transparent substrate 10 is provided with another functional layer as necessary within a range that does not impair the above-mentioned requirements such as flexibility and translucency, heat resistance, insulation, and light resistance and weather resistance. It may be. In order to improve UV resistance, heat resistance, waterproofness, and antifouling property especially when used outdoors, for example, an overcoat layer made of a fluororesin or the like on the surface of the insulating protective film 15 or the like. The case of separately laminating a coating layer capable of improving the above can be cited as an example of a preferred embodiment of the flexible transparent substrate.

<See-through type LED display device>
The LED display device 1 shown in FIG. 4 can be obtained by mounting the LED element 2 on the flexible transparent substrate 10 and integrating it with other necessary members. For example, as shown in FIG. 5, the LED display device 1 is supposed to be arranged on the front surface of a show window or the like. In this case, a person located on the front side of the LED display device 1 can visually recognize the visual information on the back side of the LED display device 1 simultaneously with the recognition of the information displayed on the LED display device 1. .. For example, as schematically shown in FIG. 5, it is possible to visually recognize the state of products and the like in the show window located on the back side of the LED display device 1 at the same time as the character information and the like displayed on the LED display device 1. Such an embodiment can be cited as an example of a preferred embodiment of the LED display device 10.

[LED element]
The LED element 2 that constitutes the see-through type LED display device 1 by being mounted on the flexible transparent substrate 10 is a light emitting element that utilizes light emission at a PN junction portion in which a P-type semiconductor and an N-type semiconductor are joined. A structure in which a P-type electrode and an N-type electrode are provided on the upper and lower surfaces of the element and a structure in which both the P-type and N-type electrodes are provided on one surface of the element have been proposed. The LED element 2 having any structure can be used in the LED display device 1 of the present invention, but in particular, an LED element with a driver IC (Wordsemi) capable of realizing control of RGB light emission in one element by a minimum current circuit arrangement. WS2812C etc.) can be particularly preferably used as the LED element mounted on the see-through type LED display device 1.

<Manufacture of flexible transparent substrate>
The method for producing the flexible transparent substrate of the present invention is not particularly limited, and it can be produced by a conventionally known method for producing an electronic substrate. An example of a specific manufacturing method will be described below.

[Etching process]
First, on the surface of the support substrate 11, the wiring part 13 such as a copper foil which is a material of the wiring part 13 is laminated to obtain a laminated body which is a material of the flexible transparent substrate 10. As a laminating method, the wiring portion 13 is laminated by a method of adhering a metal foil to the surface of the supporting substrate 11 with an adhesive. Next, an etching mask patterned in the shape of the wiring portion 13 is formed on the surface of the metal foil of the above laminated body. The etching mask is provided so that the wiring pattern forming portion of the metal foil which will be the wiring portion 13 will be protected from corrosion by the etching solution in the future. The method for forming the etching mask is not particularly limited, and for example, the etching mask may be formed on the surface of the laminated sheet by exposing the photoresist or dry film through the photomask and then developing, or an inkjet printer or the like. An etching mask may be formed on the surface of the laminated sheet by the above printing technique. Next, the metal foil in the portion not covered with the etching mask is removed with an immersion liquid. As a result, the portion of the metal foil other than the portion that becomes the wiring portion 13 is removed. Finally, the etching mask is removed using an alkaline stripping solution. As a result, the etching mask is removed from the surface of the wiring portion 13. As described above, in this etching step, the non-masked portion of the copper foil or the like is removed to form a non-conducting portion, but the adhesive layer 12 in that portion remains on the surface of the supporting substrate 11 and is completed. The adhesive layer 12 exists on substantially the entire surface of the support substrate 11 of the flexible transparent substrate 10.

Moreover, the LED element 2 can be joined to the wiring portion 13 of the flexible transparent substrate 10 preferably by soldering via a solder layer. This solder joining can be performed by a reflow method or a laser method. In the reflow method, the LED element 2 is mounted on the wiring portion 13 via solder, and then the flexible transparent substrate 10 is transported into the reflow furnace, and hot air having a predetermined temperature is blown to the wiring portion 13 in the reflow furnace. Then, the solder paste is melted and the LED element 2 is soldered to the wiring portion 13. The laser method is a method of locally heating the solder with a laser and soldering the LED element 2 to the wiring portion 13. Regarding the support substrate 11, it is preferable to subject the resin to a heat resistance improvement treatment by annealing treatment in advance, depending on the material resin selected.

[Insulation protection film formation process]
After forming the wiring portion, the insulating protection film 15 is further laminated. This lamination can be performed by a known method. Depending on the material used, a printing method such as screen printing, or various laminating treatment methods such as dry lamination and thermal lamination can be used. Among the above methods, the screen printing method is particularly preferable from the viewpoint of more completely ensuring that the surface of the adhesive layer 12 is filled with fine irregularities.

[Soldering process]
The LED element 2 can be joined to the wiring portion 13 by soldering. The joining by soldering can be performed by a reflow method or a laser method. In the reflow method, the LED element 2 is mounted on the wiring portion 13 via solder, and then the flexible transparent substrate 10 is transported into the reflow furnace, and hot air having a predetermined temperature is blown to the wiring portion 13 in the reflow furnace. Then, the solder paste is melted and the LED element 2 is soldered to the wiring portion 13. The laser method is a method of locally heating the solder with a laser and soldering the LED element 2 to the wiring portion 13. The heating in this treatment varies depending on the type of solder used, but is generally about 170° C., and particularly about 135° C. when using a low melting point solder.

When soldering the LED element 2 to the wiring portion 13, it is preferable to use a method of reflowing the solder by laser irradiation from the back surface side of the support substrate 11. As a result, it is possible to more reliably suppress the ignition of the organic component of the solder due to heating and the resulting damage to the base material.

[Contrast improvement dark part formation process]
The contrast improving dark color portion 14 can be formed by, for example, a so-called in-mold for forming the contrast improving dark color portion 14 by closing the LED display device in a mold and supplying blackened or darkened injection resin. By forming the contrast-improving dark color portion 14 by in-molding, it is possible to easily form the above-mentioned hollow ring-shaped contrast-improving dark color portion 14 having the shape of an inverse tapered side wall. When the contrast improving dark color portion is formed as the contrast improving dark color layer, an insulating thermosetting ink containing an appropriate amount of a black or dark pigment is applied by a roll coating method, a gravure roll coating method, a kiss coating method, etc. It can be formed by applying by a coating method or a printing method.

Further, for example, in the case of arranging the contrast improving dark color portion in the vicinity of the inner side of the end on the LED element, a method of forming it by integrally molding with the reflector of the LED package can be mentioned. Further, in the case of arranging the contrast-improving dark color portion in the vicinity of the outer side of the end of the LED element, a method of arranging by arranging a resin component to be attached later can be mentioned.

As described above, according to the see-through type LED display device of the present invention, it is possible to avoid a reduction in the visibility of the information displayed on the see-through type LED display device.

1, 1a LED display device 11, 11a Support substrate 12, 12a Adhesive layer 13, 13a Wiring part 14, 14a Contrast improving dark color part 141, 141a Contrast improving dark color opening 15,15a Insulating protective film 151, 151a LED element Through hole for mounting 10, 10a Flexible transparent substrate 2, 2a LED element 21, 21a Edge of LED element L1, L2 Width of contrast enhancement dark color part

Claims (3)

A see-through type LED display device comprising LED elements mounted on a flexible transparent substrate,
The flexible transparent substrate is
A supporting substrate having flexibility and having a haze value of 20% or less measured according to JIS-K7136;
A wiring portion laminated on the surface of the support substrate via an adhesive layer,
An insulating protective film which is laminated on the support substrate and the wiring part so as to cover a region other than the mounting region of the LED element and has a haze value of 20% or less measured according to JIS-K7136. ,,
In a plan view of the LED display device, a contrast-improving dark color portion is arranged in the vicinity of an inner end of the LED element,
The shape of the opening of the contrast enhancement dark color portion is such that the inner diameter of the opening is reduced from the display surface side of the LED display device toward the surface opposite to the display surface side,
The see-through type LED display device in which the ΔL ^* value of the contrast-enhancing dark-colored portion measured according to JIS-Z8722 under the conditions of a D65 light source and a 10° viewing angle is 60 or less. The LED display device according to claim 1 , wherein the coverage of the wiring portion on the support substrate is 2% or more and 10% or less. A multi-layer display surface type LED display system, further comprising a rear side display device for displaying visual information on the rear side of the LED display device according to claim 1 or 2 .

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