JPH10233534A - Led display and display device using it - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize and LED display which can be maintained in a highly reliable state even when the display is used for a long time and has a high weather resistance by filling up the space between the LED and its substrate and an enclosure with a filler and mixing an infrared-ray reflecting member in the filler. SOLUTION: A printed board 103 on which LED lamps 102 capable of emitting R, G, and B light rays are arranged in a matrix-like state and electrically connected to each other is sealed in a resin case 101 which is formed as the enclosure of an LED display with a filler 104, such as the silicon resin, etc. Then TiO2 is contained in the filler 104 as an infrared-ray reflecting member and heat radiating members are formed by inserting and fixing aluminum louvers 105 into and in the inserting sections of the case 101 formed between each LED lamp 102 so as to radiate the heat from the amps 102 to the outside after collecting the heat through the filler 104. Therefore, an LED display which can be maintained in a highly reliable state even when the display is used for a long time under a sever condition and has a high weather resistance can be obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

TECHNICAL FIELD The present invention relates to a destination display board,
LE used for LED displays and various displays
The present invention relates to a D display and the like, and more particularly, to an LED display having stable light emission characteristics even when used for a long time and having excellent reliability in the field and a display device using the same.

[0002]

2. Description of the Related Art Today, with the development of silicon technology such as LSI and optical communication technology, it has become possible to process and transmit a large amount of information. Along with this, social demands for full-color and large-sized display devices capable of processing a large amount of image information have been increasing more and more. In particular, there is an extremely high demand for a large display device that can be visually recognized by an unspecified number of people. As such a large-sized display device, a display device displaying a combination of a large number of cold cathode tubes and a liquid crystal projector using a liquid crystal filter are known. However, the above-mentioned method has a large device weight and a large device volume. In addition, maintenance and inspection are difficult because a high voltage is used for driving. The method described below has a problem that it is difficult to increase the size and the use environment is limited. For this reason, large-sized display devices have not yet reached widespread use.

[0003] On the other hand, R which can display full color recently has been developed.
Semiconductor light emitting devices capable of emitting ultra-high luminance in each of three primary colors of GB (red, green, and blue) have been developed. With the development of the LED lamp using the semiconductor light emitting device, a device using the LED lamp has been attracting attention as a large display device or the like. A display device using an LED lamp can have an extremely small device volume and device weight as compared with other display devices, and can have a long life. Further, it is relatively easy to manufacture as compared with a display or the like using a cold-cathode tube, and has extremely low driving voltage and power consumption.

In order to emit light in multiple colors, three or more types of LED chips of red, green and blue colors are arranged on a common substrate such as a stem in one LED lamp, and each of the LEDs emits light of a different color. Full color display is performed by combination. Alternatively, the display may be performed by combining LED lamps capable of individually emitting red, green, and blue light.
Specifically, when all of the RGB LED chips are turned on, white can be obtained by mixed color display. Red and green colors are yellow, and green and blue colors are cyan. Further, the brightness of each LED chip can be adjusted to provide various emission colors. Such an LED display using an LED lamp is composed of a body, an LED lamp arranged in a matrix on a base slope housed in the body, and an LED lamp.
An ED lamp and a sealing resin which is a filler for protecting the inside of the housing. In addition, a hood is integrally formed with a housing made of epoxy resin as a light shielding member for improving visibility.

[0005]

SUMMARY OF THE INVENTION However, LEDs
With the spread of the display, stable characteristics are required even in use in a more severe environment. Therefore, today, when the visibility and the reliability are required to be improved, the display device having the above configuration is not sufficient, and further improvement in the reliability and weather resistance are required. In view of the above problems, the present invention is an LED having high reliability and high weather resistance even when used for a long time.
An object of the present invention is to provide a display and a display device using the same.

[0006]

According to the present invention, there is provided a substrate on which LEDs are arranged, a housing for covering and protecting at least the periphery of the substrate and fixing the substrate, the LED, the substrate, and the housing. And a filler filled between the bodies, wherein the LED display has an infrared reflecting member during the filling. further,
In addition, a display device includes the above-described LED display and a driving circuit electrically connected to the LED display.

[0007]

The LED chip has a characteristic that the emission wavelength shifts and / or the luminance decreases as the temperature rises. Ti0 ₂ used in the present invention absorbs visible light while reflecting infrared radiation. Therefore, by suppressing the temperature rise of the LED display due to radiant heat from the outside, LED
It is possible to suppress a shift in the emission wavelength of the lamp and a decrease in luminance. Further, since the thermal expansion of the filler can be made extremely small, the adhesion between the filler and the LED lamp or the housing can be improved, and the weather resistance can also be improved. Furthermore, T
The contrast can be improved by i0 ₂ itself absorbing visible light. Therefore, a highly reliable LED display device can be obtained even when used for a long time.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has conducted various experiments,
It has been found that visibility and reliability are greatly changed by including a specific substance in the filler for protecting the LED lamp, and the inventors have made an invention based on this.

That is, an LED used under outdoor or other conditions
In the display, besides the heat that the LED lamp itself emits,
LED through filler by infrared rays from external environment
The lamp heats up. In particular, the area of the filler on the display surface is not small. Therefore, in the field or the like, the temperature rise from the LED display surface has a particularly large effect and cannot be ignored. In addition, it is considered that when the color is colored in a dark color system to improve the contrast, the influence is further increased. Such changes in the LED display caused by infrared irradiation from the external environment include modulation of the emission wavelength of the LED lamp, shift in emission brightness, and reduction in adhesion of the filler. Such a change in light emission characteristics is caused by LE
The color balance of the D display is broken and a desired color tone cannot be obtained. In addition, a decrease in adhesion of the filler due to a difference in thermal expansion coefficient or the like may cause a decrease in reliability due to penetration of moisture or the like. The present invention relates to an LED display in which an infrared reflecting member that reflects infrared rays from the external environment is contained in a filler to suppress a temperature rise of the LED display, to reduce color unevenness and / or luminance unevenness, and to improve reliability. It can be a container. Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic perspective view of the present invention, and FIG. 2 is a schematic sectional view of the present invention. An LED lamp 102 capable of emitting RGB light is arranged in a matrix in a resin case 101 which is a case, and a printed circuit board 103 electrically connected to each other is sealed with a filler 104 such as a silicon resin. Between each LED lamp, an aluminum louver 105 using a flat plate as a light-shielding and heat-collecting / dissipating member is fitted and fixed in a fitting portion of a resin case. Part of the light blocking member 105 is disposed between the LED lamps and the printed circuit board with a filler therebetween.
The filling portion 104 contains TiO ₂ as an infrared reflecting member. Therefore, each heat radiating member can collect the heat emitted from the LED lamp through the filler 104 and radiate the heat to the outside. On the other hand, the surface of the LED display is exposed to infrared rays and the like from the outside, but the infrared rays are reflected by the infrared reflecting member, so that the heat absorbed by the filler is extremely small. Therefore, deterioration of the filler due to heat, LED
Extremely little unevenness in color, unevenness in brightness, etc. due to color shift, decrease in brightness, etc. of the lamp. Hereinafter, each configuration of the present invention will be described in detail.

(Infrared Reflecting Member) The infrared reflecting member used in the present invention reflects external infrared rays which raise the temperature of the LED display surface. The infrared reflecting member contained in the filler needs to maintain sufficient adhesion with the filler. Such, Ti0 ₂ and the like as an infrared reflection member. In the case of using the Ti0 ₂ as an infrared reflection member improves the surface contrast of the display to absorb visible light as well as reflecting the infrared particularly preferred. Further, as shown in FIG. 3A, the filler may be multi-layered, and the content of the infrared reflecting member may be changed according to each layer. FIG. 3A shows the distribution of the infrared reflecting members in the thickness direction of the filler, and the distribution is larger on the upper side (surface side) and smaller on the lower side (substrate side). Similarly in FIG.
As in (B), the content of the infrared reflecting member may be continuously changed in the film thickness direction. Specifically, the number of infrared reflecting members contained in the filler provided on the front surface side of the display surface is more inclined than the number of the infrared reflecting members in the filler provided on the inner side, so that infrared rays can be efficiently emitted. Can be reflected. Such specific, Ti0 ₂ as infrared reflective member may be formed by Tsuyonetsu precipitate separated hydroxides from aqueous titanium salt solution. Formed Ti0 ₂ can also be sieved to desired particle size is obtained.

(Filler 104) As the filler 104 used in the present invention, the LED lamp 102, the casing 1
01, good adhesion to the substrate 103 on which the LED lamps are arranged, the light shielding member 105, and the infrared reflection member is required. In addition, mechanical strength and weather resistance are required to protect the internal circuit. Further, it is necessary to efficiently conduct heat generated from the LED lamp to the outside. Specific examples of such a filler include an epoxy resin and a silicone resin. Further, the filler may have a multilayer structure according to the purpose. Specifically, a filler to be first injected into the body is a first filler, such as an epoxy resin or a nylon resin containing copper oxide, silver oxide, or the like. Next, there is an example in which a filler such as a highly weather-resistant silicone resin containing an infrared reflecting member is used on the display surface side of the LED lamp as the second filler. In the above configuration, the first filler disposed inside the casing while uniformly dispersing the heat generated therein may be formed using a resin having lower weather resistance than the second filler. The respective fillers may be formed with their functions separated.

(LED lamp 102) LED lamp 10
2 is a light emitting element formed by molding various semiconductors with resin or glass. Specifically, GaAlN, ZnS, Z
nSe, SiC, GaP, GaAIAs, AIInGa
P, InGaN, GaN, InN, AlN, AlInG
A material in which a semiconductor such as aN is formed as a light emitting layer is preferably used. Semiconductor structures include MIS junction, PI
Examples include a homostructure, a heterostructure, and a double heterostructure having an N junction or a PN junction. In addition, a single quantum well structure or a multiple quantum well structure in which the light emitting layer is a thin film in which a quantum effect occurs can be used. The emission wavelength can be variously selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the degree of mixed crystal thereof.

The molding member is suitably provided to protect the LED chip and the like from the outside. Generally, it is constituted by using a resin. Also, by including a diffusing agent in the resin mold, the directivity from the LED chip can be reduced and the viewing angle can be increased. Unnecessary emission wavelengths can also be cut by including a coloring agent.
Furthermore, it can be converted to another color such as a white color using a fluorescent substance. Further, by forming the mold member into a desired shape, it is possible to have a lens effect of converging or diffusing light emitted from the LED chip.
Therefore, a structure in which a plurality of mold members are stacked may be employed. Specifically, the shape is a convex lens shape, a concave lens shape, or a combination thereof. As a material for the mold member, a translucent resin having excellent weather resistance, such as an acrylic resin, an epoxy resin, or a urea resin, is suitably used. As the diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide and the like are preferably used. Examples of the fluorescent substance include an yttrium / aluminum / garnet-based fluorescent substance and a perylene-based derivative.

When considering the use of an LED display device outdoors, it is preferable to use a gallium-based compound semiconductor as the green and blue colors for ultra-high brightness and stable light emission characteristics. It is preferable to use a gallium-aluminum-arsenic-based semiconductor or an aluminum-indium-gallium-phosphorus-based semiconductor. Further, a multicolor light emitting element in which a plurality of LED chips having different emission wavelengths are arranged on a stem as desired, for example, in order to obtain a white color with good color mixing property, can be used. For example, 2 for green
A single LED chip, one blue chip and one red chip, and one LED chip may be provided on a lead terminal and molded into an LED lamp. Note that L as a full-color display
In order to use an ED chip, the emission wavelength of red light must be 61
0 nm to 700 nm, green color is 495 nm to 565
It is preferable to use an LED chip using a semiconductor having an emission wavelength of 430 nm to 490 nm for blue and blue.

(Substrate 103) The substrate 103 on which the LED lamps 102 are arranged is used for arranging the respective LED lamps in a desired shape and electrically connecting them. They may be combined. As the substrate 103 of the present invention, a substrate having high mechanical strength and low thermal deformation is preferable. Specifically, a substrate using ceramics, glass or various resins can be suitably used. The substrate surface on which the LED lamp 102 is mounted is an LED
It is more preferable to be colored to improve the contrast because it matches the display surface. In addition, unevenness may be applied to improve the adhesion to the filler 103.

(Case 101) The case 101 used in the present invention mechanically protects the LED lamps 102 arranged in a desired shape such as a matrix form on a substrate 103 from the outside, and has a desired size. Can be formed. The body 101 preferably has excellent adhesion to the filler. As the material of the casing 101, polycarbonate resin,
An ABS resin, an epoxy resin, a phenol resin and the like are preferred. In addition, a concave portion is provided in the housing, and the angle of the light-shielding plate can be variously changed depending on the shape of the concave portion by being fitted with the convex portion of the light-shielding member. Furthermore, the inner surface of the casing 101 may be embossed to increase the bonding area, or may be subjected to plasma treatment to improve the adhesion with the filler.

(Light shielding member 105)
This prevents each of the ED lamps 102 from being difficult to recognize due to extraneous light. On the other hand, it can also be used as a heat conducting member used to collect heat generated from the LED lamp 102 via the filler 104 and radiate the heat to the outside. Specifically, it is a simple substance of aluminum or stainless steel, an alloy thereof, or the like. Further, it is preferable to color the light shielding member black or the like for the purpose of improving the light shielding efficiency.
It is more preferable that the light shielding member is configured by aligning the concave portion of the housing with the wing so that the angle can be changed in accordance with the viewing distance. As the arrangement of the light shielding member 105, the heat collection efficiency can be increased by disposing the filler 104 between the matrix-shaped LED lamps. In this case, the light blocking members 105 may be formed in a matrix between the LED lamps, or may be provided along the rows or columns between the LED lamps.

(Driving device) As a driving device, the LED of the present invention having a plurality of LED lamps having a lighting circuit and the like is arranged.
It is electrically connected to the ED display. Specifically, an LED display arranged in a matrix is driven by an output pulse from a drive circuit. A RAM for temporarily storing input display data as a drive circuit
(Random, Access, Memory) and R
A gradation control circuit that calculates a gradation signal for lighting an LED lamp to a predetermined brightness from data stored in the AM, and a driver that is switched by an output signal of the floor control circuit to light each LED lamp And The gradation control circuit calculates a lighting time and / or luminance of the LED lamp from data stored in the RAM, and outputs a pulse signal. The gradation signal, which is a pulse signal output from the gradation control circuit, is input to a driver of the LED lamp to switch the driver. The LED lamp is turned on when the driver is turned on, and is turned off when the driver is turned off. Hereinafter, embodiments of the present invention will be described, but it goes without saying that the present invention is not limited to only specific embodiments.

[0020]

【Example】

(Example 1) In order to emit multicolor light from an LED lamp, InGaN (emission wavelength: 525 nm), InGaN (emission wavelength: 470 nm), and GaAlAs (emission wavelength: 660 n) were used as semiconductors of green, blue, and red light emitting layers, respectively.
m) The semiconductor was connected to the electrical connection portion using a semiconductor, and then covered with an epoxy resin. The LED lamps were arranged in a 16 × 16 matrix on the base slope on which the conductive pattern was formed, and mounted using an automatic soldering device. This was arranged for each substrate inside a housing formed of epoxy resin and fixed with screws.

[0021] Next, as the infrared reflecting member, a titanium hydroxide was heated in a titanium salt aqueous solution Yonka, to form a powder of Ti0 ₂ by passing through a sieve. Ti0 mixing ₂ powder into silicone resin to obtain a slurry as a filler infrared reflective member containing by stirring. Except for the tip portion of the LED lamp, the housing, the LED lamp, the substrate and a part of the light shielding member were filled with a silicone resin containing an infrared reflecting member. Then, cure at room temperature and LED
The display was configured. Next, 50 LED display devices in which this LED display was electrically connected to the drive circuit were formed.

The LED display device is fully lit and the average value is x ·
In the y chromaticity diagram (Kell Chart), white (x =
0.31, y = 0.31), and then lit continuously for 1000 hours using pseudo sunlight, and the luminance and color shift at this time were observed. As a weather resistance test, a temperature of 50 ° C. and a humidity of 95% were measured using a sunshine weather meter.
Time 1 minute, temperature 20 ° C, humidity 95% time 1 minute, 50
After 0 cycles, a lighting check and an appearance check of the display device were performed.

(Comparative Example 1) Ti0 was used as an infrared reflecting member.
LED display panel and LE in the same manner as in Example 1 except that a silicone resin not containing ₂ was used as a filler.
50 D display devices were formed. The luminance and color shift of this LED display device were measured in the same manner as in Example 1, and a weather resistance test was performed. As a result of the measurement, when the average luminance of Example 1 was 1, the average of Comparative Example 1 was 0.7. In Example 1, no color shift occurred, but in Comparative Example 1, color shift occurred. Furthermore, in Example 1, there was no delamination observed at the interface between the case and the filler, and all were lit.
In Comparative Example 1, there was one that did not light up partially. As a result of observing these LED displays, peeling occurred at the interface between the casing and the filler.

[0024]

As described above, the LED of the present invention is
The display and the display device using the same have high reliability even when used for a long time under severe conditions such as outdoors,
An LED display having high weather resistance and a display device using the same can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view of an LED display of the present invention.

FIG. 2 shows the LED of the present invention in FIGS. 1A-1A.
It is a schematic sectional drawing of a display.

FIG. 3 is a schematic cross-sectional view of a filler containing the infrared reflecting member of the present invention, and FIG. 3A shows a filler having a multilayer structure. FIG. 3B shows that the content of the infrared reflecting member during filling is inclined.

[Explanation of symbols]

 101 ... today body 102 ... LED 103 ... printed circuit board 104 ... filler 105 ... light shielding member

Claims (2)

[Claims] 1. A substrate on which an LED lamp is disposed, a housing for covering and protecting at least the periphery of the substrate and fixing the substrate, and a space filled between the LED lamp, the substrate and the housing. L having a filler
An ED display, comprising an infrared reflecting member during the filling. 2. The LED display according to claim 1, wherein said LED is
A display device, comprising: a driving circuit electrically connected to the display.