JPH09186366A - LED display device and display device using the same - Google Patents

Abstract

(57) Abstract: An object of the present invention is to provide an LED display having high brightness, high reliability and high weather resistance even when used for a long time, and a display device using the same. According to the present invention, a substrate on which a plurality of LEDs are arranged, a casing for covering and protecting at least the periphery of the substrate and fixing the substrate, the LED, the substrate and the casing are provided. In an LED display having a filling material filled between the bodies, a thermal conductivity of 100 W / is provided between the LEDs arranged on the substrate via the filling material.
An LED display provided with a light shielding member of (m · K) or more and a display device using the same. [Effects] The present invention can provide an LED display device having high weather resistance and high reliability without color shift or luminance reduction even when used for a long time, and a display device using the same.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED display having excellent visibility and weather resistance and a display device using the same, and particularly to an LED display having no color shift even when used for a long time and having excellent reliability. And a display device using the same.

[0002]

2. Description of the Related Art Today, the development of silicon technology such as LSI and optical communication technology has made it 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 are increasing more and more. In particular, there is an extremely high demand for a large-sized display device that is viewed by an unspecified number of people. As such a large-sized display device, there are known a multi-vision which displays a combination of many cold cathode tubes and a liquid crystal projector which uses a liquid crystal filter.

However, the above-mentioned method has a large device weight and a large device volume. Moreover, since a high voltage is used for driving, maintenance and inspection is difficult. Alternatively, there is a problem that the usage environment is limited. For this reason, large-scale display devices have not come into widespread use. On the other hand, recently, a solid-state light emitting element (hereinafter referred to as an LED) capable of emitting full-color display RGB (red, green, blue) three primary colors with high brightness has been developed. With the development of the LED, the LED is suddenly attracting attention as a large display device and the like.
A display device using an LED can have an extremely small device volume and device weight as compared with a conventional display device, and at the same time, can have a long life. Further, it is relatively easy to manufacture as compared with a display using a conventional cold cathode fluorescent lamp, and the driving voltage and power consumption are extremely small, so that it is particularly promising as a large-sized display device. In order to make the LED emit light in multiple colors, red,
Full-color display can be performed by arranging three or more LED chips of green and blue and combining the respective emission colors. Specifically, when all the LED chips are turned on, it becomes white, red and green become yellow, and green and blue become cyan. Further, the brightness of each LED can be adjusted to produce various kinds of emission colors. The LEDs are arranged in a matrix on the substrate, and the space between the LEDs, the substrate and the casing is protected by a filler, and the LED can be used as an LED display. L like this
Examples of the ED display include JP-A-7-261674 and JP-A-7-288342.

A specific example of a display device using LEDs is shown in FIG.
And FIG. This LED display capable of full-color display includes a casing 501, LEDs 503 arranged in a matrix on a substrate 502 housed in the casing, and L
And an encapsulating resin 504, which is a filler that protects the ED and the inside of the housing. A hood 505 is integrally formed with a casing 501 made of an epoxy resin as a light shielding member to improve visibility.

However, in the present day when the visibility and the reliability are required to be improved, the display device having the above structure is not sufficient, and further improvement in the reliability and high durability are required.

[0006]

SUMMARY OF THE INVENTION In view of the above problems, the present invention is L, which has high reliability and weather resistance even when used for a long time.
An object is to provide an ED display device and a display device using the same.

[0007]

DISCLOSURE OF THE INVENTION The present invention includes a plurality of LEs.
An LED having a substrate on which D is arranged, a casing for covering and protecting at least the periphery of the substrate and fixing the substrate, and the LED and a filling material filled between the substrate and the casing. In the display, heat conductivity of 10 is provided between the LEDs arranged on the substrate through a filler.
It is an LED display provided with a light shielding member of 0 W / (m · K) or more. It is an LED display in which a plurality of LEDs are arranged in a matrix. The invention of the present application is the L
The ED is an LED display including a semiconductor having an emission wavelength of 610 to 700 nm, a semiconductor having an emission wavelength of 495 to 565 nm, and a semiconductor having an emission wavelength of 430 to 490 nm. Further, it is a display device including the above-mentioned LED display device and a driving unit electrically connected to the LED display device.

[0008]

With the structure of claim 1 of the present invention, the heat emitted from the LED is collected and released to the outside, so that deterioration of the luminous intensity of the LED can be suppressed and the life of the LED can be extended. Further, since the adhesion between the filler and the casing is improved, it is possible to prevent dust, water and the like from entering the inside of the casing. It is possible to improve external quantum efficiency and suppress power consumption. Further, by adopting the constitution of claim 2 of the present invention, it is possible to reduce a change due to color shift as a display device. With the configuration according to claim 3 of the present invention, color shift due to deterioration of luminous intensity can be suppressed and reliability can be improved even in full-color display in which a large amount of heat is generated. In particular, it is possible to prevent a color shift due to a shift in the luminance characteristic of each semiconductor and a shift in the luminance characteristic due to the difference in durability.
With the configuration according to claim 4 of the present invention, it is possible to provide an LED display device having high reliability even when used for a long time.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As a result of various experiments, the inventor of the present invention has newly found that the visibility and reliability are greatly changed depending on the structure of the housing in which the LED is protected and the specific arrangement of the light shielding member. Came to invent. The present invention will be described in detail below.

The LED is an external heating or LED
There is a problem in that the emission brightness is modulated by the heat generated by the emission of light and the desired emission color cannot be obtained. Particularly in an LED that emits multiple colors, there is a problem that a large amount of heat is generated and a large change in luminance appears as uneven color. Further, there is a problem that the characteristics of the luminance change with respect to the temperature change are different for each semiconductor having a different emission wavelength and the difference in the thermal durability characteristics is that the luminance change for each semiconductor appears as color unevenness of the entire display. In some cases, the emission wavelength of the semiconductor used for the LED may shift even further. On the other hand, when an LED display device is constructed by using a member having good heat dissipation as a housing, the difference in the coefficient of thermal expansion of the housing, the printed circuit board supporting the LEDs, and the encapsulating resin as a filler, and the resin Due to the deterioration, the adhesion between the casing and the filler may be deteriorated and may be partially peeled off. When peeling occurs, water, dust, and the like enter the inside of the display device, and the emission brightness of the LED decreases. In severe cases, the LED and its drive circuit may be destroyed and display may not be possible. In particular, the frame interface of the housing is that there is no substrate on which the LED is placed, so the mechanical strength is weak and water and dust easily enter the inside of the display device and the drive circuit side.
There is a problem that the ED display is easily destroyed. In order to solve the above-mentioned problems, the inventor of the present application configures a casing and a light-shielding member separately, and improves the adhesion between the light-shielding member that performs a light-shielding and heat collecting / dissipating function through the filler and the filler. (EN) An LED display in which color misregistration is reduced and reliability is improved by functionally separating it into a tubular structure, and a display device using the same. Hereinafter, the present invention will be described in detail with reference to the drawings.

FIG. 1 is a schematic sectional view of the present invention, and FIG. 2 is a schematic schematic diagram of the present invention. A printed circuit board 10 in which LEDs 102 are arranged in a matrix and electrically connected to each other in a resin case 101 which is a casing.
3 is filled with a filling material 104 such as a silicone resin. Between each LED, a convex portion of a flat plate aluminum louver 105 using a flat plate of aluminum alloy as a light-shielding / collecting / radiating member is fitted and fixed in a fitting portion of a resin case. A part of the light shielding member 105 is arranged between each LED and the printed circuit board via a sealing resin which is a filling material 104. Therefore, each heat dissipation member can collect the heat emitted from the LED through the filler 104 and dissipate the heat to the outside. On the other hand, the casing 101 does not directly collect the heat generated from the LED 102 or has a small amount of heat.
The temperature change due to the heat generation of D is low, and the case 1
It is considered that the adhesion of the filler 104 on the frame side portion 01 of 01 is improved. Further, even if the adhesiveness between the light shielding member 105 and the filling material 104 is lowered and the light shielding member 105 may be partially peeled off, the substrate 103 is provided under the substrate 103, and sufficient mechanical strength can be maintained. Therefore, it is considered that the adhesion on the frame side is improved, the mixing of impurities is prevented, and the reliability is significantly improved. Each component of the present invention will be described below.

(Ceiling body 101) This is an article for mechanically protecting an LED arranged in a desired shape such as a matrix on a substrate from the outside and can be formed in a desired size. As the housing, since the light shielding member has a heat collecting / dissipating function, it is less likely to be affected by heat from the LED, but a material having a small coefficient of thermal expansion is preferable in consideration of adhesion with the filler. Further, as the material of the casing, a polycarbonate resin, an ABS resin, an epoxy resin, a phenol resin or the like is preferable in view of ease of molding. It is preferable that the housing be provided with a recess for fixing the light shielding member so that the arrangement of the light shielding member does not change due to the deformation of the filler or the light shielding member due to the temperature change. As a result, the visibility can be improved and the stress of the light blocking member and the encapsulating resin can be dispersed. The angle of the light shielding plate can be changed depending on the shape of the recess. Alternatively, a fixing portion such as a screw may be provided. Further, the inner surface of the housing may be embossed to increase the adhesion area, or plasma treatment may be performed to improve the adhesion to the filler. Since the light-shielding member having high thermal conductivity of the present invention is arranged between the LEDs, it functions as a light-shielding member by extending a part of the casing as an LED light-shielding plate at the top or bottom of the casing. You can also have it.

(LED 102) As the LED 102, a light emitting element formed by molding various kinds of semiconductors with resin is used. One type of semiconductor in the LED may emit monochromatic light, or a plurality of semiconductors may be used to emit monochromatic or multicolored light. Specifically, GaA is formed on the substrate by liquid phase epitaxy or MOCVD.
1N, ZnS, ZnSe, SiC, GaP, GaAlA
s, AlInGaP, InGaN, GaN, AlInG
A material in which a semiconductor such as aN is formed as a light emitting layer is used. Examples of the semiconductor structure include a homo structure, a hetero structure, and a double hetero structure having a MIS junction and a PN junction. The emission wavelength can be selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and its degree of mixed crystal. The LED mold is provided to protect each LED chip and the like from the outside. Generally, it is constituted by using a resin. Further, by including a diffusing agent in the resin mold, it is possible to reduce the directivity from the LED and increase the viewing angle. Further, by forming the resin mold into a desired shape, it is possible to have a lens effect of converging or diffusing the light emitted from the LED. Therefore,
The resin mold may have a laminated structure. Specifically, it is a convex lens shape, a concave lens shape, or a combination thereof. Further, the resin mold itself may be colored to serve as a filter for cutting out unwanted wavelengths. As a material of the resin mold, a transparent resin having excellent weather resistance such as an epoxy resin and a urea resin is suitably used. As the diffusing agent, barium titanate, titanium oxide, aluminum oxide, silicon oxide and the like are preferably used.

When considering the use of an LED display device outdoors, it is preferable to use gallium nitride-based compound semiconductors for the green and blue systems, and gallium-aluminum-arsenic-based semiconductors and aluminum-based systems for the red system.
It is preferable to use an indium-gallium-phosphorus semiconductor. The effect of the present invention is particularly great in the above-described LED of the semiconductor, which has a large amount of heat generation and a different semiconductor material in place of high emission brightness. Also, if desired, LEDs with different wavelengths
It is also possible to use a multicolor light emitting device in which a plurality of chips are arranged on the stem. For example, two blue LEDs and one green LED and one red LED can be used. In this case as well, the amount of heat generated is particularly large, so the effect of the present invention is great. In order to use an LED as a color display, a red emission wavelength is 610 nm to 700 nm, a green emission wavelength is 495 nm to 565 nm, and a blue emission wavelength is 430 n.
It is preferable to use LEDs using semiconductors from m to 490 nm.

(Substrate 103) The substrate 103 on which the LEDs 102 are arranged is used for arranging the LEDs in a desired shape and electrically connecting them, and may also serve as a substrate for a drive circuit in some cases. Is also good. The arrangement of LEDs can be matrix shaped when used for display. Further, as long as the light shielding member of the present invention can be arranged, the LEDs may be arranged as desired such as arrow signals. As the substrate 103 of the present invention, a substrate having high mechanical strength and low thermal deformation is preferable. Specifically, a printed circuit board made of ceramics, glass, aluminum alloy or the like can be preferably used. Since the surface of the substrate on which the LED is mounted coincides with the LED display surface, it is preferable that the surface of the substrate is colored to improve the contrast. In addition, the filler 103
In order to improve the adhesiveness with

(Filler 104) As the filler 104,
It is required that the LEDs 102, the housing 101, the substrate 103 on which the LEDs are arranged, and the light shielding member 105 have good adhesion. In addition, mechanical strength and weather resistance are required to protect the internal circuit. Furthermore, it is necessary to efficiently conduct heat generated by the LED to the light shielding member. The thermal conductivity is preferably 0.1 W / (m · K) or more, more preferably 0.15 W / (m · K) or more. Specific examples of such a filler include epoxy resin, urethane resin, and silicone resin. Further, a coloring dye may be contained in these resins in order to improve the contrast. Further, a heat conducting member may be included for the purpose of improving heat conduction. Since the heat conducting member is also arranged between the LEDs, it is required not to conduct electricity. Specific examples thereof include copper oxide and silver oxide.

(Light-shielding member 105) Light-shielding member 1 of the present invention
05 prevents each of the LEDs 102 from becoming hard to be visually recognized by external light. On the other hand, it is also a heat conducting member used for collecting the heat generated from the LED 102 through the filling material 104 and radiating it outside. In the invention of the present application, if the light-shielding member has good thermal conductivity, the thermal expansion is inevitably small, which is particularly preferable. Therefore, the heat conductivity of the light shielding member 105 is preferably 100 W / (m · K) or more, and more preferably 130 W / (m · K) or more. Specifically, it is a simple substance of aluminum or copper or an alloy thereof. These thermal conductivities can be selected depending on the composition of the alloy. That is,
Mg, Si, Fe, Cu, Mn, C in the base metal
By incorporating a desired amount of another metal such as r, Zn, Ni, Ti, Pb, or Sn, the thermal conductivity, the expansion coefficient of the metal, the hardness, etc. can be selected. Further, the light-shielding member can be made into a multi-layered structure by using different members to have a plurality of functions such as electromagnetic wave absorption and heat radiation. In order to improve the heat dissipation effect, it is preferable to increase the surface area of the light shielding member. Specifically, the shape of the light shielding member may be a corrugated shape, or the structure of the light shielding member may be a honeycomb shape or a porous member. FIG. 4 shows a light blocking member that is preferably used in the present invention. FIG.
In (A), the structure of the light-shielding portion is a multilayer in which copper is sandwiched between aluminum alloys. In FIG. 4B, the central portion of the light shielding portion has a porous shape. In FIG. 4C, the shape of the light shielding member is a wavy shape. Further, it is possible to improve the cooling and heat radiation effects by changing only the shape of the light shielding member which is not in contact with the light shielding member which is in contact with the filler. Further, it is preferable to color the light shielding member in black or the like for the purpose of improving the light shielding efficiency. It is preferable that the light shielding member is configured as a concave portion of the housing so that the angle can be changed according to the viewing distance. Further, by changing the angle of the light shielding member, the electromagnetic waves emitted from the LED can be efficiently absorbed. In this case, it can be selected as desired depending on the viewing angle and distance, but is preferably 0 to 10 with respect to the vertical of the substrate 103.
Degree is preferred. As the arrangement of the light shielding member 105, the heat collection efficiency can be further improved by disposing the light shielding member 105 between the LEDs in a matrix with the filler 104 interposed therebetween. in this case,
The light blocking member 105 is arranged between the LEDs in a matrix, that is,
It may be formed in a cross shape, or may be provided along rows or columns between the LEDs.

(Driving Means 301) The driving means 301 used in the present invention is one electrically connected to an LED display 302 having a lighting circuit and a plurality of LEDs arranged therein. Specifically, an LED display arranged in a matrix or the like is driven by an output pulse from a driving circuit. As the drive circuit, a RAM (Random Access) that temporarily stores input display data is used.
Memory) and the data stored in the RAM.
A gradation control circuit that calculates a gradation signal for lighting the ED to a predetermined brightness, and a driver that is switched by the output signal of the gradation control circuit to light the LED. Such a driving means can be formed by using a CPU. The gradation control circuit calculates the lighting time of the LED from the 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 the driver of the LED to switch the driver. The LED can be turned on when the driver is turned on and turned off when the driver is turned off. Less than,
Embodiments of the present invention will be described, but it goes without saying that the present invention is not limited to only specific embodiments.

[Embodiment 1] In order to emit light of multiple colors, LEDs are made of InGaN (emission wavelength 525 nm), InGaN (emission wavelength 470 nm), GaAlAs (emission wavelength 660 n) as semiconductors of green, blue and red emission layers, respectively.
m) The semiconductor was connected to the electrical connection portion using a semiconductor, and then covered with an epoxy resin. The LEDs were arranged in a 7 × 7 matrix on a printed board. Next, it was placed and fixed inside a casing formed of a phenol resin. Next, using aluminum as the base material, Mg, S
A part of a light-shielding member, which is a flat plate of an aluminum alloy containing i, Fe, Cu, Mn, Cr, and Zn, is matched with a concave portion provided in a housing, and the LED is arranged on the substrate. Hold vertically. The thermal conductivity of the aluminum alloy is 138 W / (m · K). A part of the light shielding member is inserted between rows of LEDs arranged in a matrix. Except for the tip of the LED, LE, LE
D, a part of the substrate and the light shielding plate were filled with silicone rubber. Then, it was cured at room temperature to form an LED display. Next, this LED display was electrically connected to a drive circuit to form the LED display shown in FIG.

LE by BM-7 manufactured by TOPUKON
The average value of the D display device is the xy chromaticity diagram (Kell Cha
At rt) when white (x = 0.28, y = 0.31)
Was measured. A color misregistration test was performed by continuously lighting at room temperature for 1000 hours. As a weather resistance test, 500 cycles of a temperature of 50 ° C., a humidity of 95%, a time of 1 minute and a temperature of 20 ° C., a time of 1 minute were performed for 500 cycles to check the lighting and appearance of the display device. The measurement results are shown in Table 1 in comparison with Comparative Examples 1 and 2 by setting the result of Example 1 as 1.

[Comparative Example 1] An LED display panel and an LED display device were formed in the same manner as in Example 1 except that the casing and the light shielding member were made of phenol resin.
This LED display device was measured in the same manner as in Example 1.

[Comparative Example 2] The case and the light-shielding member were made of aluminum as a matrix, and Mg, Si, Fe, Cu, Mn,
An LED display panel and an LED display device were formed in the same manner as in Example 1 except that they were each formed of an aluminum alloy containing Cr and Zn. The thermal conductivity at this time is 138 W / (m · K). This LED display device was measured in the same manner as in Example 1. From the results of Table 1, it was found that the display device using the LED display device of the present invention was clearly superior to the display device shown for comparison in reliability, weather resistance and brightness.

[0023]

As described above, the present invention can provide an LED display having high reliability even after long-term use and high weather resistance, and a display device using the same.

[Brief description of the drawings]

FIG. 1 is a schematic cross-sectional view of an LED display device of the present invention.

FIG. 2 is a schematic diagram of an LED display of the present invention.

FIG. 3 is a schematic diagram of a display device using the LED display device of the present invention.

FIG. 4 is a light-shielding member preferably used in the present invention.

FIG. 5 is a schematic sectional view of an LED display shown for comparison with the present invention.

FIG. 6 is a schematic diagram of an LED display shown for comparison with the present invention.

[Explanation of symbols]

 101 Housing 102 LED 103 Printed Circuit Board 104 Filling Material 105 Light Shielding Member 301 Driving Means 302 LED Display 501 Housing 502 On Board 503 LED 504 Encapsulating Resin 505 Hood

[Table 1] Regarding the weather resistance, ◯: No change in appearance was found on the frame side, Δ: Cracks were found.

Claims (4)

[Claims] 1. A substrate on which a plurality of LEDs are arranged, a casing for covering and protecting at least the periphery of the substrate and fixing the substrate, and a space between the LED, the substrate and the casing. In a LED display having a filling material, a light-shielding member having a thermal conductivity of 100 W / (m · K) or more is provided between the LEDs arranged on the substrate via the filling material. LED display. 2. The LED display according to claim 1, wherein the plurality of LEDs are arranged in a matrix. 3. The LED has an emission wavelength of 610 to 700.
nm semiconductor, a semiconductor having an emission wavelength of 495 to 565 nm, a semiconductor having an emission wavelength of 430 to 490 nm,
The LED display according to claim 1, further comprising: 4. The LED display according to claim 1, and the LED.
A display device, comprising: a drive unit electrically connected to the display unit.