JP7270532B2 - Display unit and display device - Google Patents

Description

The present invention relates to display units and display devices.

A display screen of a large display device is configured by arranging a plurality of display units in a matrix. The display unit includes a circuit board, a plurality of light emitting elements mounted in a matrix on the circuit board, and a reflection suppressing member having a canopy that suppresses the incidence and reflection of external light such as sunlight.

In this type of display device, when it snows, snow adheres to the antireflection member having the eaves, causing a problem that light emitted from the light emitting elements is blocked. Therefore, a display unit has been developed that includes a heating element that generates heat when energized. For example, Patent Literature 1 discloses a display unit in which a heating element is attached to a reflection suppressing member and the heat of the heating element is conducted to the reflection suppressing member to heat the reflection suppressing member.

JP 2019-174646 A

In the prior art, the snow adhering to the antireflection member is melted by increasing the temperature of the surface of the antireflection member. However, in order to reliably melt the snow under severe weather conditions such as heavy snowfall, strong winds, and low temperatures, a large amount of heat is required, resulting in a problem of increased energy consumption. Further, when the antireflection member is provided away from the heating element, the temperature of the surface of the antireflection member cannot be increased sufficiently. Therefore, in order to increase the temperature of the entire surface of the antireflection member, it is necessary to install heat generating elements densely over the entire antireflection member. Therefore, the structure of the display unit becomes complicated.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a display unit and a display device which have a simple structure and are capable of melting snow.

To achieve the above object, a display unit according to the present invention includes a plurality of light emitting elements mounted on a circuit board. Moreover, the display unit includes a reflection suppressing member that covers the circuit board. Further, the display unit includes a heating element provided on the antireflection member. The antireflection member includes a back surface facing the circuit board and a front surface opposite to the back surface. The antireflection member has a base portion having an opening for accommodating the light emitting element, and an eaves portion provided on the surface of the base portion and protruding in a direction perpendicular to the surface. The eaves are hydrophilic, and the surface of the base is water-repellent .

In the display unit according to the present invention, at least part of the antireflection member is hydrophilic. Therefore, water tends to stay in the reflection suppressing member, and the staying water contributes to snow melting, so energy consumption can be suppressed, and snow can be melted with a simple structure.

1 is a perspective view of a display device according to Embodiment 1 of the present invention; 1 is a front view of a display unit according to Embodiment 1 (a) A cross-sectional view along line AA in FIG. 2, (b) A cross-sectional view along line BB in FIG. CC arrow cross-sectional view of FIG. 3 (b) 1 is a block diagram showing an electrical configuration of a display device according to an embodiment; FIG. Cross-sectional view of a display unit provided with a hydrophilic treatment film according to Embodiment 2

Display unit 10 and display device 100 according to the present embodiment will be described below with reference to the drawings.

In addition, the same code|symbol is attached|subjected to the part which is the same or corresponds in each figure. For ease of understanding, the Y-axis direction is the rising direction of the display unit 10 and the display device 100 according to the present embodiment, and the X-axis direction and the Y-axis direction are the horizontal directions of the display unit 10 and the display device 100. XYZ orthogonal coordinates are set with the direction perpendicular to the X-axis direction as the Z-axis direction.

Embodiment 1
First, the display device 100 according to Embodiment 1 will be described.
As shown in FIG. 1, the display device 100 is configured by arranging a plurality of display units 10 for displaying images in a matrix on a support frame 200 . A display surface 101 is a surface on which an image is displayed in the display device 100 .

Each display unit 10 is laid out in a matrix on the support frame 200 and fixed to the support frame 200 by screws or the like.

2 is a front view, FIG. 3(a) is a cross-sectional view taken along the line AA in FIG. 2, and FIG. 3(b) is a cross-sectional view taken along the line BB in FIG. , a case 40, a circuit board 20 provided in the case 40, a plurality of light emitting elements 30 mounted on a mounting surface 22 of the circuit board 20, and a louver 50 functioning as a reflection suppressing member having a hydrophilic film 53. And prepare.
Among the louvers 50 , those that particularly prevent external light from entering the light emitting elements 30 are sometimes referred to as eaves 52 .

The circuit board 20 is made of an insulating resin material, glass material, ceramic material, or the like. A display control circuit and a heating element drive circuit, which will be described later, are formed on the circuit board 20 . The circuit board 20 also has a mounting surface 22 on which mounted components are arranged on the display surface 101 side.
Each light emitting element 30 functions as a pixel forming an image, and displays the image as a whole. The light-emitting elements 30 are formed of 3-in-1 type surface-mounted LED elements and mounted in a matrix on the mounting surface 22 of the circuit board 20 . For example, as shown in FIG. 2, they are mounted in a matrix of 7 rows×7 columns.

As shown in FIGS. 3A and 3B, the case 40 is composed of a frame, and has a first opening 41 which is an opening on the display surface 101 side and an opening on the side opposite to the display surface 101. and a second opening 42 . The case 40 is formed in a frame shape by combining four linear members made of a resin material such as polycarbonate resin or acrylic resin. Further, the cross-sectional central portion of each linear member is processed to have a concave shape, and a concave portion is provided. The peripheral edge portions of the circuit board 20 and the protective portion 23 are accommodated in this concave portion.

The louver 50 is arranged to cover the first opening 41 of the case 40, as shown in FIGS. The circuit board 20 is provided with wiring (not shown) for supplying electric power to the light emitting element 30, mounted parts, and the like. Therefore, when external light enters the circuit board 20, it is reflected by the wiring and is visually recognized as reflected light. The louver 50 suppresses the occurrence of reflected light by blocking external light from entering the circuit board 20 .

The louver 50 is made of a resin material by injection molding, and includes a flat plate-shaped base portion 51 and a plurality of eaves portions 52 provided on the base portion 51 .

The base portion 51 includes a back surface 51a and a front surface 51b opposite to the back surface 51a. Further, the rear surface 51a is arranged to face the mounting surface 22 of the circuit board 20 with the protective portion 23 interposed therebetween. Both the back surface 51 a and the front surface 51 b are formed parallel to the display surface 101 . Further, the base portion 51 has a thickness of dimension TH1. As shown in FIG. 4 , the base portion 51 has openings 54 formed in a matrix to accommodate the light emitting elements 30 arranged on the mounting surface 22 of the circuit board 20 . Therefore, in this embodiment, the openings 54 are formed in 7 rows×7 columns.

The eaves portion 52 is provided on the surface 51b of the base portion 51, protrudes in the direction perpendicular to the display surface 101, that is, in the Z-axis direction, and attenuates external light incident from oblique directions. The eaves 52 extend in the X-axis direction between the rows of the openings 54 in the vertical direction (Y-axis direction) of the base 51 and between the upper and lower sides of the base 51 in parallel to each other. is provided. In this embodiment, as shown in FIGS. 3B and 4, eight eaves 52 are provided at equal intervals. Moreover, as shown in FIGS. 2 and 3A, the horizontal length of the eaves portion 52 is the same as the horizontal length of the base portion 51 .

As shown in FIGS. 3A and 3B, the louver 50 is formed with a transparent or black hydrophilic film 53 having hydrophilicity. The hydrophilic film 53 is formed by applying hydrophilic paint. As a result, the water adhering to the louver 50 blends with the hydrophilic film 53 formed on the surface of the louver 50 .

As shown in FIGS. 3A and 3B, a protective portion 23 is provided between the base portion 51 and the mounting surface 22 of the circuit board 20 to protect the mounting surface 22 from foreign substances such as water and dust. It is The protective portion 23 is made of a resin material having water repellency, such as silicone resin or epoxy resin.

As shown in FIGS. 3A, 3B, and 4, a plurality of first heating wires 61 are provided extending in the X-axis direction below the plurality of eaves 52. As shown in FIGS. The first heating wire 61 is a metal wire made from a material such as nichrome, which is an electrothermal conductive metal. In addition, the first heating wire 61 may not only be embedded in the base portion 51 of the louver 50 but also partially contact the base portion 51 . Alternatively, it may be embedded in the eaves portion 52 . Further, the first heating wire 61 may be provided in contact with a metal material or the like having high thermal conductivity provided on the base portion 51 of the louver 50 .

As shown in FIG. 3( a ), the end of the first heating wire 61 is connected to a first communicating portion 68 extending in the direction opposite to the display surface 101 . The first communicating portion 68 is a metal wire similar to the first heating wire 61, passes through the protective portion 23 and the circuit board 20, and is connected to the connector 29 provided on the opposite side of the mounting surface 22 of the circuit board 20. are doing.

As shown in FIG. 4, the ends of adjacent first heating wires 61 are connected to each other by a second heating wire 62 extending in the Y-axis direction. The second heating wire 62 is also embedded in the base portion 51 . The first heating wire 61, the second heating wire 62, and the above-described first communication portion 68 constitute one continuous heating wire 60 (heating element). The first heating wire 61 and the second heating wire 62 are preferably integrally molded with the base portion 51 when the louver 50 is injection molded.
In addition, in FIG. 4, in order to represent the positional relationship between the eaves portion 52 and the first heating wire 61, the portion where the eaves portion 52 is provided on the surface 51b is indicated by a dashed line.

Next, the electrical configuration of the display device 100 will be described. As shown in FIG. 5 , the display device 100 includes a first power supply circuit 91 that supplies externally input power to the plurality of light emitting elements 30 of each display unit 10 , and a first power supply circuit 91 that supplies externally input power to each display unit 10 . , a second power supply circuit 92 that supplies power to each of the heating wires 60, and a control device 90 that performs various controls. An outside air temperature sensor 70 is connected to the control device 90 and outputs outside temperature data to the control device 90 .

Furthermore, an external indicator 110 is connected to the control device 90 . The external indicator 110 outputs a display instruction signal that instructs the image to be displayed to the control device 90 . The external indicator 110 is installed in a command room or the like that issues a command to the display device 100 .

The control device 90 executes various controls including drive control of the light emitting element 30 and power supply control to the heating wire 60 .

In driving control of the light emitting element 30 , the control device 90 first performs various conversion processes on the display instruction signal supplied from the external indicator 110 . Various conversion processes performed by the control device 90 include enlargement/reduction processing of an image in accordance with the screen size of the display device 100, image quality enhancement processing, and the like. Next, based on the converted display instruction signal, a PWM (Pulse Width Modulation) signal for controlling the light emitting element 30 is generated and output to the driving circuit 28 of each display unit 10 .

The first power supply circuit 91 includes an AC/DC conversion circuit. The AC/DC conversion circuit converts an alternating current with a constant voltage input from the outside into a direct current, and outputs the direct current to the control device 90 and the drive circuit 28 of each display unit 10, respectively.

The drive circuit 28 controls the voltage of the direct current supplied from the first power supply circuit 91 to a voltage determined according to the duty ratio of the PWM signal input from the control device 90 and outputs the voltage to the light emitting element 30 . The light emitting element 30 emits light upon receiving power supplied from the driving circuit 28 .

The second power supply circuit 92 includes an AC/AC conversion circuit and a switch circuit 93 . The AC/AC conversion circuit converts an alternating current with a constant voltage input from the outside into an alternating current with a voltage suitable for driving the heating wire 60 . The heating wire 60 provided in each display unit 10 is connected to the second power supply circuit 92 through the connector 29 provided in each display unit 10, and receives power supplied from the second power supply circuit 92 to generate heat. do.

The switch circuit 93 is connected to the control device 90 and controls the conductive state of the electric path connecting the second power supply circuit 92 and the heating wire 60 based on the output from the control device 90 . When the switch circuit 93 is in a conducting state (on), an alternating current converted into a voltage suitable for the heating wire 60 is output to the heating wire 60 of the display unit 10 . When the switch circuit 93 is in a non-conducting state (OFF), supply of alternating current from the second power supply circuit 92 to the heating wire 60 is interrupted.

Further, the control device 90 controls on/off of the switch circuit 93 based on the output value from the outside air temperature sensor 70 . For example, when the control device 90 determines that the outside air temperature is lower than the predetermined set temperature α based on the output value of the outside air temperature sensor 70 , the control device 90 turns on the switch circuit 93 to supply power from the second power supply circuit 92 . Power is supplied to the hot wire 60 . On the other hand, when the control device 90 determines that the outside air temperature is equal to or higher than the predetermined set temperature α based on the output value of the outside air temperature sensor 70 , the control device 90 turns off the switch circuit 93 to turn off the power from the second power supply circuit 92 . Power supply to the hot wire 60 is stopped.

The set temperature α is preferably set to a temperature at which the snow adhering to the louver 50 continues to remain without melting when it is assumed that snow has fallen. For example, it can be set to 3°C to 5°C. However, it is not limited to these.

Next, the function of the louver 50 having the hydrophilic film 53 formed thereon will be described.
Heat is transferred to the louver 50 by the heat generated by the heating wire 60, and the surface temperature of the louver 50 rises. As a result, the snowflakes adhering to the louver 50 are melted, and the water becomes familiar with the surface of the louver 50 due to the hydrophilic film 53 on the surface of the louver 50, spreads, and stays. The snowflakes that next hit the louver 50 are absorbed by the remaining water by the hydrophilic film 53 and are easily melted. When a large amount of snowflakes collide and the snow does not melt in time, snow temporarily accumulates, but the accumulated water melts or slides down because the accumulated water intervenes between the accumulated snow and the surface of the louver 50.例文帳に追加

The contact angle θ1 of water with respect to the louver 50 having the hydrophilic film 53 is preferably 50 degrees or less, more preferably 30 degrees or less. When the contact angle θ1 exceeds 50 degrees, when snow adheres to the louver 50, water droplets move from the surface of the louver 50 toward the snow, resulting in low melting efficiency. Such a phenomenon can be suppressed when the contact angle θ1 is 50 degrees or less. When the contact angle θ1 is 30 degrees or less, water spreads on the surface of the louver 50 without forming droplets, forming a thin water film. Forming a thin water film increases the efficiency of melting. In addition, when there is a temperature distribution on the surface of the louver 50, water moves from a high-temperature portion to a low-temperature portion, thereby accelerating snow melting in the low-temperature portion. Furthermore, by preventing the formation of water droplets after melting, it is possible to prevent degradation in visibility due to light scattering or the like when the display device 100 emits light as a display board.

As a method of imparting hydrophilicity to the louver 50, the method of applying hydrophilic paint to the louver 50 has been exemplified in the above description, but other methods are also possible.
For example, a plasma treatment of exposing the louver 50 to plasma, a flame treatment of oxidizing the surface of the louver 50 by flame, and other chemical treatments are applied to modify the surface region of the louver 50 . It is also possible to mix an additive that improves

For example, various organic and inorganic hydrophilic paints can be used as the hydrophilic paint for forming the hydrophilic film 53 . As the organic hydrophilic paint, those based on general resins such as urethane, acryl, alkyd, silicone and fluororesin to which hydrophilic resins and hydrophilic inorganic substances such as silica are added can be used. In the case of these paints, the visibility of the display unit 10 can be improved by coloring them black by adding a black pigment such as carbon black, a dye, or the like.

As the inorganic hydrophilic paint, for example, a metal alkoxide such as silicate, titanium alkoxide, zirconium alkoxide, etc. is used, and a solidified inorganic particle can also be used. These are also preferably colored black like organic hydrophilic paints. Also, for example, a method of applying colloidal particles such as silica or alumina is effective. Since the inorganic paint can be formed into a thin film, not only does the color change slightly when applied to a black base, but it is also possible to impart an anti-reflection effect due to light interference by setting the film thickness.

As for the coating method, the surface of the louver 50 may be subjected to base treatment and undercoating as necessary, and then the hydrophilic coating may be applied by any coating method such as spray coating, dip coating, or brush coating.

The film thickness of the hydrophilic film 53, that is, the film thickness of the paint layer is preferably 1 μm or more and 200 μm or less in the case of organic hydrophilic paint. If the film thickness is less than 1 μm, peeling of the film tends to occur during use, and the film cannot withstand long-term use. If the film thickness is more than 200 μm, the cost of the paint increases and the shape of the louver 50 is affected.

In the case of an inorganic hydrophilic paint, the film thickness of the hydrophilic film 53 is preferably 0.1 μm or more and 2 μm or less. If it is less than 0.1 μm, sufficient hydrophilicity cannot be obtained. A film thickness of more than 2 μm is not preferable because peeling or the like tends to occur. When applying colloidal particles, the thickness is preferably 0.02 μm or more and 0.5 μm or less. If it is less than 0.02 μm, sufficient hydrophilicity cannot be obtained. A film thickness exceeding 0.5 μm is not preferable because it tends to peel off and becomes cloudy, leading to a decrease in visibility as a display unit.

When the louver 50 is made hydrophilic by applying a hydrophilic paint, unlike other methods, the material of the louver 50 can be a material other than resin, such as metal or ceramics, which can provide the same function. have the advantage of being able to

The surface temperature of the louver 50 when the snow melts is preferably 3° C. or higher and 60° C. or lower. Below 3°C, snow melts slowly. If the temperature exceeds 60° C., the melting speed is not improved, leading to waste of input energy. In addition, the generation of steam becomes noticeable, which may lead to a decrease in visibility as a display unit.

Embodiment 2
In Embodiment 1, the entire surface of the louver 50 is made hydrophilic, but it is also possible to make only the portion that contributes to snow melting hydrophilic. The display unit 10 according to Embodiment 2 having such a configuration will be described below. As shown in FIG. 6, in the display unit 10, a hydrophilic film 53 is formed on the upper surface of the eaves portion 52 of the louver 50 to make it hydrophilic. Since water remains in the hydrophilic film 53, snowflakes are likely to adhere to the portion where the hydrophilic film 53 is formed. Therefore, the snow can be melted more efficiently than when the entire surface of the louver 50 is made hydrophilic. Although not shown, the portion of the louver 50 where the hydrophilic film 53 is not formed is an untreated resin surface, which is a water-repellent surface. This portion may be subjected to a water repellent treatment to enhance water repellency. For example, a paint containing silicone or fluororesin, or a paint whose water repellency is enhanced by the addition of silicone, fluorine compound, or the like can be used.

In addition, in the second embodiment, the portion to which snow easily adheres is limited and made hydrophilic, leaving a water-repellent portion in the periphery, so that the water generated in the hydrophilic portion does not easily flow over the water-repellent portion. Therefore, it becomes easy for water to remain in the hydrophilic portion without flowing away. Also, the existence of a sufficient amount of water in the portion where snowflakes tend to adhere facilitates the progress of melting. In addition, since a large amount of water tends to exist and stay in the portion of the hydrophilic film 53, accumulated snow tends to slide off.

Further, in Embodiment 2, since the surface of the louver 50 on which the hydrophilic film 53 is not formed is maintained water-repellent, snow accretion does not increase on this portion. Therefore, even if snowflakes adhere, no energy is required for melting.

The hydrophilicity of the hydrophilic film 53 is preferably approximately the same as that of the hydrophilic film in the first embodiment. The water repellency of the louver 50 is preferably such that the contact angle θ2 of water with respect to the louver 50 exceeds 50 degrees, more preferably 60 degrees or more. At 50 degrees or less, the effect of suppressing movement of water is small, and partial hydrophilization is difficult to occur.

The hydrophilic film 53 according to the second embodiment can be formed by the hydrophilic method shown in the first embodiment. As a method for forming the hydrophilic film 53 by painting, a spray method is easy. Hydrophilic film 53 can be formed on desired portions by spraying diagonally above louver 50, which is the direction in which snowflakes mainly collide.

When both the hydrophilic treatment and the water-repellent treatment are carried out, the hydrophilic paint is sprayed obliquely from above, and the water-repellent paint is sprayed obliquely from below. A method of spraying a water-repellent paint from above, a method of making the entire surface water-repellent and then spraying a hydrophilic paint from obliquely above, and the like can be employed. In particular, the former two methods are preferable due to the ease of application of the hydrophilic paint and the high stability of the hydrophilic film after application.

Embodiment 3
The display unit is exposed to various contaminants such as dust, smoke, exhaust gas, etc. in the usage environment, and adhesion of these substances to the surface causes deterioration of hydrophilicity of the surface. In the hydrophilization treatment of Embodiments 1 and 2, by applying a dispersion of inorganic nanoparticles and fluororesin, it is possible to suppress the deterioration of hydrophilicity due to contamination and melt snow. can.

The configurations of the display device and the display unit in this embodiment are the same as those in the first or second embodiment.

The hydrophilic film of Embodiment 3 is formed of a film having a structure in which a porous thin film in which inorganic nanoparticles are aggregated and solidified is impregnated with a dispersion liquid in which fine fluororesin is dispersed. This hydrophilic film is produced, for example, by preparing a dispersion containing inorganic nanoparticles and water-repellent resin particles, applying this dispersion to the surface of the louver 50, drying it, and aggregating it.

In the present embodiment, a water-repellent resin may exist on the surface of the display unit, but since this is distributed in dots on the continuous hydrophilic surface, the film as a whole maintains high hydrophilicity, and the effect of snow melting. does not affect

The hydrophilic film of this embodiment has two physical properties of hydrophilicity and water repellency. Such a surface exhibits the property that neither hydrophilic nor water-repellent adherents stick to it easily, and these adherents can be easily removed with water. Therefore, even in an environment that is easily polluted, high hydrophilicity is maintained, and the snow-melting effect is less likely to decrease.

The inorganic nanoparticles that make up the dispersion are not particularly limited as long as they can form a porous hydrophilic coating, and examples include silicon, magnesium, aluminum, titanium, cerium, tin, zinc, germanium, indium, and antimony. fine particles of elements such as , and fine particles of oxides and nitrides of these elements. Further, inorganic fine particles which are not themselves hydrophilic may be treated with various substances to make them hydrophilic. These inorganic fine particles can be used alone or in combination of two or more.

The average particle size of the inorganic nanoparticles is preferably 3 nm or more and 100 nm or less, more preferably 5 nm or more and 70 nm or less. If the average particle diameter is less than 3 nm, the hydrophilic film may become too dense, and the hydrophilicity and antifouling properties may deteriorate. If the average particle size exceeds 100 nm, the hydrophilic film will easily peel off.

The water-repellent resin constituting the dispersion is not particularly limited, but is preferably a fluororesin that is stable against ultraviolet light and heat. coalescence), PFA (tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer), ETFE (ethylene-tetrafluoroethylene copolymer), ECTFE (ethylene-chlorotrifluoroethylene copolymer), PVDF (polyvinylidene fluoride), PCTFE (polychlorotrifluoroethylene), PVF (polyvinyl fluoride), fluoroethylene-vinyl ether copolymer, fluoroethylene-vinyl ester copolymer, copolymers and mixtures thereof, and other resins to these fluororesins A mixture of

As the water-repellent resin, one in which solid particles or liquid particles are dispersed in a liquid is used. The average particle diameter is preferably 50 nm or more and 500 nm or less, more preferably 100 nm or more and 250 nm or less. If the average particle size is less than 50 nm, the film will be homogeneous and the characteristic antifouling property cannot be obtained. When the average particle size exceeds 500 nm, the film tends to peel off, and dust tends to adhere due to unevenness.

The mass ratio of the inorganic nanoparticles to the water-repellent resin in the dispersion is preferably 60:40-98:2, more preferably 70:30-98:2. If the ratio of the water-repellent resin is higher than the above range, the exposed surface of the water-repellent resin becomes too large, and the hydrophilicity as a whole decreases. On the other hand, if the ratio of the water-repellent resin is too small, the exposure of the water-repellent resin is too small, resulting in the same antifouling property as in the case of only the inorganic nanoparticles.

The solvent that constitutes the dispersion liquid is not particularly limited, but water or a hydrophilic solvent can be used. For example, alcohols such as ethanol, methanol, 2-propanol and butanol; ketones such as acetone, methyl ethyl ketone and diacetone alcohol; esters such as ethyl acetate, methyl acetate, cellosolve acetate, methyl lactate, ethyl lactate and butyl lactate; Organic acids such as acetic acid; ethers such as methyl cellosolve, cellosolve, butyl cellosolve, and dioxane; glycols such as ethylene glycol, diethylene glycol, and propylene glycol; diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, propylene glycol monomethyl ether, 3-methoxy- glycol ethers such as 3-methyl-1-butanol; glycol esters such as ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, diethylene glycol monobutyl ether acetate and diethylene glycol monoethyl ether acetate; and N-methylpyrrolidone. These can be used singly or in combination of two or more.

The solid content concentration in the dispersion is not particularly limited, but is preferably 0.1% by mass or more and 20% by mass or less. The solid content here is the component remaining after removing the vaporized component (solvent, etc.) by heating at 100°C. If the solid content concentration is less than 0.1% by mass, the hydrophilic film becomes too thin, and desired hydrophilicity and antifouling properties may not be obtained. If the solid content concentration exceeds 20% by mass, the hydrophilic film becomes too thick, defects such as cracks and voids occur, and the film tends to peel off, failing to obtain the desired antifouling performance.

A dispersion liquid having such a structure is prepared, applied to the louver 50, and dried. In addition, the surface of the louver 50 may be subjected to base treatment or undercoating as necessary. Spray coating, dip coating, brush coating, or the like can be used to apply the agglomerates. It is also possible to form the louver 50 by immersing it in a dispersion and drying it. The film thickness of the aggregate film is preferably 0.02 μm or more and 0.5 μm or less as an average film thickness. If the thickness is less than 0.02 μm, sufficient hydrophilicity cannot be obtained, and the contained fluororesin is likely to peel off. A film having a thickness of more than 0.5 μm is easily peeled off and becomes cloudy, leading to deterioration in visibility as a display unit.

EXAMPLES The present invention will be described in detail below with reference to Examples and Comparative Examples, but the present invention is not limited to these.

Comparative example 1
Using the display unit 10 shown in FIG. 2, a snow melting test was conducted as a control test. The contact angle θ between the louver 50 and water was 65 degrees, and the surface of the louver 50 exhibited water repellency. The display unit 10 was installed in an artificial climate chamber at -20°C, and the heating element was energized to raise the temperature. When the temperature of the eaves portion 52 of the louver 50 was measured with a radiation thermometer, the temperature varied depending on the distance from the heating element, and the temperature was about 20°C at the high temperature portion and about 0°C at the peripheral low temperature portion.

Snowfall with a snowfall intensity of 4 cm/h was applied to the display unit 10 in this state. After a sufficient amount of time had passed, the high-temperature areas had a sufficient snow-melting effect, but the low-temperature areas tended to be covered with snow.

Example 1
After framing the louver 50 of the display unit 10 shown in FIG. 2, NIPPE CRYSTACOAT was spray-coated as a hydrophilic paint. The contact angle θ between the louver 50 and water was 25 degrees. The display unit 10 provided with this louver 50 was evaluated in the same manner as in Comparative Example 1.

Although the surface temperature of the louver 50 was the same as in Comparative Example 1, a sufficient snow-melting effect was observed in the high-temperature portion. In addition, only a small amount of snow adhered was observed even in the low temperature area. From the above, it was confirmed that by applying a hydrophilic paint to the surface of the louver 50, the efficiency of snow melting is greatly improved, and a good snow melting effect can be obtained even in low temperature areas.

Example 2
First, frame processing was performed on the louver 50 of the display unit 10 shown in FIG. Then, colloidal silica having an average particle size of about 5 nm (Nikki Shokubai Kasei Cataloid SI550); 2% by weight, polyurethane emulsion (ADEKA BONDITTER HUX-840); 3% by weight, polyoxylethylene lauryl ether; 0.2% by weight. It was immersed in an aqueous dispersion containing and dried. By this treatment, the surface of the louver 50 was covered with a hydrophilic resin film, and the contact angle θ between the louver 50 and water became 30 degrees. The display unit 10 provided with this louver 50 was evaluated in the same manner as in Comparative Example 1, and the same effect as in Example 1 was recognized.

Example 3
Only the upper surface portion of the louver 50 of the display unit 10 shown in FIG. 2 was subjected to hydrophilization treatment. The eaves 52 were subjected to framing from obliquely above the louver 50, and only the upper surface of the eaves 52 was subjected to framing. After that, colloidal silica having an average particle size of about 5 nm (JGC Shokubai Kasei Cataloid SI550); 2.0% by weight, acrylic emulsion (Boncoat 5400EF); Lauryl ether; an aqueous dispersion containing 0.2% by weight was sprayed.

The coated portion was covered with a hydrophilic resin film, and the contact angle θ between the coated portion and water was 27 degrees. The contact angle θ between the portion not subjected to hydrophilization treatment and water was 63 degrees. The display unit 10 provided with this louver 50 was evaluated in the same manner as in Comparative Example 1, and the same effect as in Example 1 was recognized.

Comparative example 2
As a control experiment for Examples 4 and 5, which will be described later, the display unit 10 used in Comparative Example 1 was subjected to oil smoke treatment (contamination treatment). The display unit 10 was installed in a box with an internal volume of 1 m ³ , and 0.3 g of salad oil was heated to 200° C. in this box to generate soot, while 3 g of carbon black dust was added. The box was left for 5 minutes while oily smoke and dust were circulated in the box by wind.

The contact angle θ between the louver 50 and water became 74 degrees due to the contamination treatment. A snowfall test similar to Comparative Example 1 was performed using the display unit 10 subjected to the contamination treatment. Slight snow accretion was observed on the contaminated display unit 10 .

Example 4
The display unit 10 of Example 2 was subjected to the same contamination treatment with soot as in Comparative Example 2. Although the contact angle θ between the louver 50 and water became 42 degrees due to the contamination treatment, hydrophilicity was maintained.

Next, the same snowfall test as in Comparative Example 1 was performed using the contaminated display unit 10 . In the display unit 10 of Example 2, only a small amount of snow adhered to the peripheral low temperature area. On the other hand, in the display unit 10 subjected to the contamination treatment, more snow adhered to the low temperature portion than in the case of using the display unit 10 of Example 2. Therefore, although high snow-melting efficiency is maintained, the reduction in efficiency was observed due to the pollution treatment.

Example 5
Frame processing was performed on the louver 50 of the display unit 10 shown in FIG. Then, colloidal silica with an average particle size of about 5 nm (Nikki Shokubai Kasei, Cataloid SI550); 1.2% by weight, colloidal silica with an average particle size of about 25 nm (Nikki Shokubai Kasei Cataloid SI50); 0.3% by weight, fluororesin dispersion Liquid (AGC, AD911E): immersed in an aqueous dispersion containing 0.8% by weight and dried. The contact angle between the louver 50 and water after the treatment was 25 degrees.

After that, in the same manner as in Comparative Example 2, contamination treatment was performed by exposing to oil smoke. Even after the contamination treatment, the contact angle θ between the louver 50 and water was 28 degrees, and high hydrophilicity was maintained.

Next, the same snowfall test as in Comparative Example 1 was performed using the display unit 10 after the contamination treatment. Even after a sufficient amount of time had passed, only a small amount of snow adhered to the surrounding low-temperature areas, demonstrating high snow-melting efficiency.

In Example 5, high snow melting efficiency was maintained even when exposed to oil smoke, carbon dust, etc., and it was confirmed that the louver 50 acquired hydrophilicity and antifouling properties through the treatment in this example. From the above, it can be seen that a good snow-melting effect that is less susceptible to contamination can be obtained.

The display device 100 exemplified in Embodiments 1 to 3 can be installed on a highway or a general road and used as a road information display device that displays warning information or various road information. Also, it can be installed in an outdoor stadium or the like as an image display device other than the road information display device.

Although the display unit 10 and the display device 100 have been described above using the first to third embodiments as examples, the display unit 10 and the display device 100 are not limited to the first to third embodiments.

Reference Signs List 10 display unit 20 circuit board 22 mounting surface 23 protection part 28 drive circuit 29 connector 30 light emitting element 40 case 41 first opening 42 second opening 50 louver 51 base part 51a Back surface 51b Front surface 52 Overhead part 53 Hydrophilic film 54 Opening 60 Heating wire 61 First heating wire 62 Second heating wire 68 First communication part 70 Outside air temperature sensor 90 Control device 91 Third 1 power supply circuit, 92 second power supply circuit, 93 switch circuit, 100 display device, 101 display surface, 110 external indicator, 200 support frame.

Claims (7)

a plurality of light emitting elements mounted on a circuit board;
a reflection suppressing member covering the circuit board;
and a heating element provided in the reflection suppressing member,
The antireflection member is
a base portion including a back surface facing the circuit board and a surface located opposite to the back surface and having an opening for accommodating the light emitting element;
an eaves portion provided on the surface of the base portion and protruding in a direction perpendicular to the surface;
The eaves portion is hydrophilic ,
wherein the surface of the base portion is water repellent;
display unit. The eaves portion comprises a hydrophilic membrane,
The display unit according to claim 1. The hydrophilic film contains inorganic nanoparticles and water-repellent resin particles,
The display unit according to claim 2. the antireflection member contains metal and/or ceramic,
The display unit according to any one of claims 1-3. The upper surface of the eaves portion is hydrophilic,
The display unit according to any one of claims 1-4. The surface of the base portion has water repellency around the eaves portion ,
The display unit according to any one of claims 1-5. Having the display unit according to any one of claims 1 to 6 ,
display device.

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