JP2003017755A - Light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light emitting device with high luminance and contrast ratio and a display device which can realize high contrast display in high precision and large angle of visibility, concerning the light emitting device or display device using a semiconductor light emitting device used for a display capable of indicating various kinds of data, a light source of a line sensor or an optical sensor for photo interruptor, etc. SOLUTION: This light emitting device is provided with a light emitting element arranged within a recessed part of a package and a mold member placed on the light emitting element arranged in the recessed part, and the mold member contains a diffusing agent that reduces the drop rate of LED luminance than that of dark luminance of the light emitting device. The light emitting device is used in a display device.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display capable of displaying various data, a light emitting device using a light emitting element used for a light source of a line sensor, an optical sensor such as a photo interrupter, and a display device. , Especially a light emitting device with high emission brightness and contrast ratio and high definition using the same,
The present invention relates to a display device capable of high contrast display with a wide viewing angle.

[0002]

2. Description of the Related Art Today, semiconductor light emitting devices capable of emitting light of ultrahigh brightness of 1000 mcd or more are formed in RGB. A light emitting device using such a light emitting element has begun to be used in various fields such as an LED display capable of full color light emission indoors or outdoors and various sensors and indicators. As an example of a light emitting device using such a semiconductor light emitting element, there is a surface mount type LED as shown in FIGS. 5 (A), 5 (B) and 5 (C). The surface mount type LED can be mounted by the chip mounter and the solder reflow like other surface mount type electronic parts such as a chip resistor. The surface-mounted LED can be miniaturized and can be mounted in a relatively high density and with reliability.

In such a light emitting device, a light emitting element 503 is provided on a package 502 formed of various resins such as epoxy resin and liquid crystal polymer, ceramics and the like.
Are arranged and electrically connected to the outside by an external electrode 504. The light emitting element 503 and the external electrode 504 are electrically connected by a conductive wire such as a gold wire or an electrical connection member 505 which is a conductive adhesive using Ag paste. Further, a light-transmitting mold member 501 is provided on the light emitting element 503 to protect it from the external environment. The surface mount type LED has no lens effect or has a small lens effect, and thus can be visually recognized from a wide range and has a wide viewing angle. On the other hand, the front brightness becomes low. Therefore,
As shown in (B) and (C), light emitted from the light emitting element 503 is reflected on the inner surface of the milky white or white package to improve the light emission efficiency. By supplying electric power to such a light emitting device from the outside, the light emitting device can efficiently emit light.

[0004]

However, such a light emitting device cannot be used as a light emitting device having high brightness and high contrast ratio. Specifically, when the light emitting device is used as a display device or an optical sensor, the front luminance when the light emitting device is emitting light and the dark luminance when the light emitting device is not emitting light (outside brightness when the LED is not lit) It is preferable that the difference in the front reflection brightness due to light is large. That is, a display device or the like can emit light of a desired color by turning on the light emitting device. On the other hand, when the light emitting device is not lit, the black color is displayed. Therefore, a clearer image can be displayed by using a display device having a large contrast ratio ((LED front luminance + front reflection luminance) / front reflection luminance), which is the difference between light emission and non-light emission. Similarly, even when the light emitting device is used for the optical sensor, the light emitting device with less malfunction can be obtained.

In order to increase the difference between the time of light emission and the time of non-light emission, the surface of the package other than the light emitting portion on the side of the light emission observation surface is made black, or the package contains a black colorant or the like to improve the contrast. It is possible to earn a ratio.

However, in the case where the surface on the light emission observation surface side is colored in a dark color system, the contrast ratio is not greatly improved because the area of the dark color portion cannot be made large with respect to the area of the package opening in which the light emitting element is mounted. Therefore, even if the surface on the light emitting surface side except the light emitting portion is made to be a dark color system, the contrast ratio is improved from 27/1 to 44/1, and a sufficient contrast ratio cannot be obtained.
Further, the one in which only the surface is colored in a dark color system causes a decrease in the contrast ratio because the side wall portion of the inner wall of the package opening in which the light emitting element is arranged has a high reflectance depending on the viewing angle.

Further, the dark resin area ratio can be increased by coloring the molding resin, etc., which is the package itself, in a dark color system. However, the reflection by the side wall of the inner wall of the package opening can hardly be used. Therefore, LE
D The front brightness is reduced to less than half that of the white molded resin product. The decrease in the front brightness (LED front brightness + dark brightness) becomes too large with respect to the decrease in the dark brightness. for that reason,
Not only the front brightness is lowered, but the contrast ratio is 32 /
It will be about 1. In either case, the light emitting device cannot have a high LED front luminance and a high contrast ratio. Therefore, an object of the present invention is to provide a light emitting device having higher brightness and a higher contrast ratio, and a display device using the same.

[0008]

The present invention is a light emitting device having a light emitting element arranged in a package recess and a mold member arranged on the light emitting element arranged in the recess. In particular, the mold member contains a diffusing agent that makes the LED luminance reduction rate smaller than the dark luminance reduction rate of the light emitting device.

In the light emitting device according to the second aspect of the present invention, the light emitting elements are at least three types of light emitting elements capable of emitting RGB light.

A light emitting device according to a third aspect of the present invention is a light emitting device having a light emitting element arranged in a recess of a package and a mold member for protecting the light emitting element. In particular, the mold member contains a diffusing agent. Further, the thickness from the light emitting element to the side surface of the package is larger than the thickness of the molding member on the light emitting element.

A light emitting device according to a fourth aspect of the present invention has a dark colorant in the package or on the light emitting surface side surface.

A display device according to a fifth aspect of the present invention has surface-mounted LEDs arranged in a dot matrix and driving means for driving the surface-mounted LEDs. Further, the surface-mounted LED package is of a dark color type, and is sealed with a mold member in which a diffusing agent is dispersed in the recessed opening of the package in which the surface-mounted light emitting element is mounted.

In the light emitting device of the present invention, the light emitted from the light emitting element is diffused by the diffusing agent before reaching the side wall of the inner wall of the package opening. Therefore, there is no absorption loss in the side wall of the inner wall of the package opening. On the other hand, since the mold member on the light emitting element has a small amount of the diffusing agent, diffusion and absorption of light can be suppressed. Therefore, while suppressing the LED brightness decrease (reduce the LED brightness decrease rate)
The contrast ratio can be improved.

Particularly, by coloring the package forming the light emitting device in a dark color such as black, or by printing the light emitting surface side of the light emitting device in black, it is possible to reduce the influence on the decrease in the LED brightness and to remarkably reduce the dark brightness. Can be lowered.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various experiments, the present inventor found that the reduction rate of dark brightness and the LE by adding a diffusing agent.
It was found that a light emitting device which can emit light with higher contrast and higher brightness can be obtained by utilizing the difference in the reduction rate of D brightness, and the present invention has been accomplished.

That is, there is a case where a light-emitting diode such as a shell type is usually made to contain a diffusing agent to cause a diffusing effect. However, if a light diffusing material is contained in such a light emitting diode, the light emission brightness is reduced. The present invention has found that even if a diffusing material is contained in a specific mold member or package, the light emission brightness from the LED is conversely improved. In the light emitting device of the present invention, by including a diffusing agent in the mold member, the LED luminance reduction rate (LED is lower than the dark luminance reduction rate (the rate of reduction of the front reflection luminance due to the external light when the LED is not lit)). The ratio of the decrease in the front brightness of the light emitting device is small, and the light emitting device has a high light emitting brightness and a high contrast.

More specifically, as shown in FIG. 2, the light emitting element 203 is placed in the recess of the package 202 made of liquid crystal polymer or the like. An external electrode 204 is provided on the package 202 so that it can be electrically connected to the outside. The electrode of the light emitting element 203 and the external electrode 204 are
Each is electrically connected by a conductive wire 205 such as a gold wire. In addition, a light-transmitting mold member 201 is provided on the light emitting element 203 to protect the semiconductor from the external environment.
Is provided. Particularly, in the present invention, carbon black is contained in the resin forming the package 202 in order to improve the contrast ratio rather than using the reflection from the light emitting element by the inner wall of the package opening, and a dark color system such as black or gray is used. It is packaged. On the other hand, in the mold member, the diffusing agent 211 is included in consideration that the inner wall of the package opening is also a dark color system and the use of reflection on the inner wall of the package opening cannot be expected. This diffusing agent 2
The inclusion of 11 diffuses the light emitted from the light emitting element toward the inner wall of the package opening as shown by the arrow in FIG. Further, the mold member is arranged on the light emitting element, but since the mold member is thin with respect to the distance to the inner wall of the package opening, absorption and scattering of light is small. Therefore, the reduction of the light emission brightness is suppressed. Hereinafter, each configuration of the present invention will be described in detail. (Mold Member 101, 201) The mold member 201 of the present invention is provided to protect each light emitting element 203 and wires for electrical connection thereof from external force, dust, water and the like. Further, in order to improve the dark brightness while effectively extracting the light from the light emitting element 203, the diffusing agent 211 is used.
Is included. The mold member 201 is made of the diffusing agent 21.
1 by containing 1 than the dark brightness reduction rate LED
As long as the reduction rate of the front luminance is small, it may be formed in one layer, or may be formed in two or more layers as desired, such as a multilayer structure in which the concentration of the diffusing agent 211 and the refractive index are different. Similarly, not only the cross-sectional shape, but also a multi-layer structure having different diffusion concentrations such as increasing annually the concentration of the diffusing agent as seen from the side of the emission observation surface can be adopted. Such a mold member 20
Specific examples of the material 1 include organic members made of resin having excellent weather resistance such as epoxy resin, urea resin, silicon resin, fluorine resin, and polycarbonate resin, and SiO2,
An inorganic member such as Al2O3 is preferably used. In a use environment where the temperature cycle is severe, it is more preferable that the mold member has a thermal expansion coefficient close to that of the package or the like.

The mold member 2 which constitutes the light emitting device.
01 contains various additives such as a colorant, a light stabilizer and a fluorescent substance, if desired, as long as the LED front luminance reduction rate is smaller than the dark luminance reduction rate by including the diffusing agent 211. You can also This makes it possible to adjust the light emission peak from the light emitting element 203 and reduce the directivity to increase the viewing angle. In addition, a light emitting device having a desired emission wavelength can be used. Further, the light emitting device can be more weather resistant even when used outdoors.

The colorant is contained in the mold member 201 and has a filter effect for cutting out an undesired wavelength out of the light emitted by the light emitting element 203 to improve the light emitting characteristics. Therefore, various dyes and / or pigments are variously selected according to the emission color of the light emitting device (main emission wavelength which is the main peak of emission).

Since the light emitted from the light emitting element 203 has a monochromatic peak wavelength, it is possible to form a light emitting device displaying a white color by combining it with a fluorescent substance or the like. In this case, by using a blue gallium nitride-based compound semiconductor with a large emission wavelength energy and a ytrim / aluminum oxide-based fluorescent material added with cerium or a fluorescent material that is a perylene-based derivative, it is possible to achieve high brightness efficiently. It can emit light.

Further, in addition to the diffusing agent used in the present invention, a colorant, a light stabilizing member, a fluorescent substance, etc., which can be contained, are dispersed in the mold member at various ratios to be formed. Is also good. That is, the content concentration can be increased or decreased as it approaches the light emitting element, and various selections can be made. (Diffusing Agent 211) The diffusing agent 211 contained in the mold member 201 reduces the scattering absorption of the light emitted from the light emitting element 203 and is emitted to the light emission observation surface side, and is diffused to the inner wall side of the opening in the package. By scattering a large amount of directed light, the emission brightness of the light emitting device is improved. Also,
By adjusting the content of the diffusing agent 211, the dark brightness of the package opening in which the light emitting element 203 is arranged can be adjusted. As such a diffusing agent 211, an inorganic member such as barium titanate, titanium oxide, aluminum oxide or silicon oxide, or an organic member such as melamine resin, CTU guanamine resin or benzoguanamine resin is preferably used.

In order to show the effect of the present invention, the relationship with the concentration of the diffusing agent using the organic member benzoguanamine resin as the mold member 201 arranged in the package colored black with car black as a dark color system is shown in FIG. Shown in.

From FIG. 4, if the dispersion concentration of the diffusing agent increases,
The front brightness of the light emitting device increases. This is because the light emitted from the light emitting element goes not only in the front direction of the emission observation but also in the inner wall direction of the package opening, so that the lost light absorbed by the side wall is guided to the front side due to scattering of the diffusing material. Conceivable. Also, if the diffusing agent concentration is too high,
On the contrary, the front brightness starts to decrease. It is considered that this is because the ratio of direct light scattered from the LED chip, which is a light emitting element, increases, and the increase in front luminance reaches a ceiling. Further, it is considered that as the concentration of the diffusing agent increases, the effect of external light entering is scattered and reflected, and the effect of lowering the dark brightness is imparted. It has been confirmed that almost the same tendency can be obtained with other inorganic materials.

In particular, when the LED display is viewed indoors or outdoors, there is a possibility that various external light such as sunlight may enter. Therefore, the dark brightness of the LED display should be sufficiently reduced and the contrast ratio should be 50 or more. For example, visibility is extremely reduced due to external light reflection. Therefore, the concentration of the diffusing agent depends on the material etc.
-12% is preferable. This optimizes the increase in frontal brightness. Further, the diffusing agent can prevent external light from directly reaching the external electrodes or the like provided on the bottom surface of the package, or even when reaching the external electrodes or the like, reflection and scattering to the outside can be suppressed. Therefore, it is possible to strengthen the tendency for the dark luminance to decrease. Thereby, the contrast ratio can be optimized to 50 or more. Further, a spherical polymer or the like can be suitably used in a range of 0.1 to 20 μm, but if it is too small, the dispersibility is poor, and if it is too large, it tends to settle out easily, so 1 to 5 μm is more preferable. The concentration of this diffusing agent is one or more orders of magnitude higher than the concentration of diffusing that is normally used in bullet-type light emitting diodes. Since the thickness of the mold member on the light emission observation surface side is made thin, even if it is contained by one digit or more, the decrease in the front luminance of the LED can be small. (Packages 102, 202) The package 202 has an external electrode 204 for fixing and protecting the light emitting element 203 in the concave portion and capable of being electrically connected to the outside. Therefore, the package 202 having a plurality of openings can be formed according to the number and size of the light emitting elements 203. Further, preferably, in order to have a light-shielding function, it is colored in a dark color system such as black or gray, or the light emission observation surface side of the package is colored in a dark color system. Package 2
02 is provided with a mold member 201 which is a translucent protector in order to further protect the light emitting element 203 from the external environment.
The package 202 preferably has good adhesiveness to the mold member 201 and higher rigidity than the mold member. In order to improve the adhesiveness with the mold member 201 and to direct the force that acts from the mold member 201 during thermal expansion to the outside, it is preferable that the cylindrical portion has a slanted shape that expands toward the outside. Further, it is desired to have an insulating property in order to electrically shut off the light emitting element 203 and the outside. Furthermore, when the package 202 is affected by heat from the light emitting element 203 or the like, it is preferable that the package 202 has a small coefficient of thermal expansion in consideration of adhesion with the mold member 201. Package 2
The inner surface of the concave portion of 02 may be embossed to increase the adhesion area, or plasma-treated to improve the adhesion to the mold member 201. Package 202 is
The external electrode 204 may be formed integrally with the external electrode 204, or the package 202 may be divided into a plurality of parts and combined by fitting or the like. Such a package 202
Can be formed relatively easily by insert molding or the like.

Polycarbonate resin, polyphenylene sulfide (PP
S), liquid crystal polymer (LCP), ABS resin, epoxy resin, phenol resin, acrylic resin, resin such as PBT resin, or ceramics can be used. Various dyes and pigments are preferably used as the colorant for coloring the package 202 in a dark color system. Specifically, Cr
Preferable examples include 2O3, MnO2, Fe2O3 and carbon black.

The light emitting element 203 and the package 202 can be bonded to each other with a thermosetting resin or the like. Specifically, an epoxy resin, an acrylic resin, an imide resin, or the like can be given. Further, in order to fix the light emitting element 203 and to electrically connect it to the external electrode 204 in the package 202, Ag paste, carbon paste,
Metal bumps or the like can be used. (External Electrodes 104, 204) The external electrodes 204 are used to supply electric power from the outside of the package 202 to the light emitting element 203 arranged inside. Therefore, various ones such as those using a conductive pattern provided on the package or a lead frame can be used. Further, the external electrode 204 can be formed in various sizes in consideration of heat dissipation, electrical conductivity, characteristics of the light emitting element 203, and the like. The external electrode 204 preferably has good thermal conductivity in order to dispose the light emitting elements 203 and to radiate the heat emitted from the light emitting elements 203 to the outside. The specific electric resistance of the external electrode 204 is preferably 300 μΩ · cm or less, and more preferably,
It is 3 μΩ · cm or less. Also, the specific thermal conductivity is
It is preferably 0.01 cal / cm 2 / cm / ° C or higher, more preferably 0.5 cal / cm 2 / cm / ° C or higher. As such an external electrode 204, a copper or phosphor bronze plate whose surface is plated with a metal such as silver, palladium or gold or a solder plating is preferably used. When a lead frame is used as the external electrode 204, it can be used in various ways depending on electric conductivity and thermal conductivity, but a plate thickness of 0.1 mm to 2 mm is preferable from the viewpoint of workability. As the external electrode 204 provided on a substrate such as glass epoxy resin or ceramic, a copper foil or a tungsten layer can be formed. When a metal foil is used on the printed board, the thickness of the copper foil or the like is preferably 18 to 70 μm. Further, gold, solder plating or the like may be applied on the copper foil or the like. (Light-Emitting Element 113, 123, 133, 203) As the light-emitting element 203 used in the present invention, a liquid phase growth method or M
InN, AlN, GaN, etc. are formed on the substrate by the OCVD method or the like.
ZnS, ZnSe, SiC, GaP, GaAs, GaA
lAs, GaAlN, AlInGaP, InGaN, A
A material in which a semiconductor such as lInGaN is formed as a light emitting layer is preferably used. Examples of the semiconductor structure include a MIS junction, a homo structure having a PIN junction or a PN junction, a hetero structure, or a double hetero structure. The emission wavelength can be variously selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the mixed crystallinity thereof. Furthermore, in order to have a quantum effect, the light emitting layer may have a single quantum well structure or a multiple quantum well structure.

The semiconductor thus formed is subjected to a vacuum deposition method, heat,
A desired electrode is formed by using various CVD methods utilizing light, discharge energy and the like. The electrodes of the light emitting element 204 may be provided on one side of the semiconductor or on both sides thereof. Directly full cut the semiconductor wafer on which the electrode is formed with a dicing saw with a blade having a diamond blade tip, or after cutting a groove with a width wider than the blade edge width (half cut), the semiconductor wafer is cut by an external force. Break. Alternatively, an extremely thin scribe line (meridian line) is drawn on the semiconductor wafer by, for example, a grid pattern by a scriber in which the diamond needle at the tip moves reciprocally in a straight line, and then the wafer is split by external force to cut the semiconductor wafer into chips and emit light. An LED chip, which is an element, can be formed.

In order to allow the light emitting device to emit full-color light, an LED chip that emits RGB light emission colors can be used. In particular, when using outdoors, it is preferable to use gallium nitride-based compound semiconductors for green and blue as a high-luminance semiconductor material, and gallium / aluminum / arsenic or aluminum / indium / gallium / phosphorus for red. Although it is preferable to use a system semiconductor, various types can be used depending on the application.

In order to use a light emitting element capable of emitting RGB light as a light emitting device capable of full color light emission, a red light emission wavelength is 600 nm to 700 nm,
It is preferable to use an LED chip that uses a semiconductor having a green wavelength of 495 nm to 565 nm and a blue wavelength of 400 nm to 490 nm. (Electrical Connection Members 105, 205) Electrical Connection Member 20
5, the ohmic property with the electrode of the light emitting element 203,
Good mechanical connectivity, electrical conductivity, and thermal conductivity are required. When a conductive wire is used, the thermal conductivity is preferably 0.01 cal / cm2 / cm / ° C or higher, more preferably 0.5 cal / cm2 / cm / ° C or higher. The diameter of the conductive wire is preferably Φ10 μm or more and Φ45 μm or less in consideration of workability and the like. Specific examples of such a conductive wire include a conductive wire using a metal such as gold, copper, platinum, or aluminum, or an alloy thereof. Such a conductive wire can easily connect the electrode of each light emitting element 203 and the external electrode 204 etc. by a wire bonding device.

When a conductive paste is used, it can be used by incorporating conductive C, ITO, ZnO, Ag, metal bumps, etc. into a desired resin such as an epoxy resin. By using such a conductive paste, not only electrical conduction but also fixing of the light emitting element 203 can be achieved. (Substrate) A substrate is preferably used for arranging each light emitting device in a desired shape such as a matrix and electrically connecting them. Such a substrate may be used not only for disposing the light emitting device but also as a substrate for a drive circuit. Therefore, it is preferable that the substrate has high mechanical strength and little thermal deformation. Specifically, ceramics on which a conductive pattern such as a tungsten layer is formed, glass epoxy resin on which a conductive pattern such as a copper foil is formed, and a metal or an alloy having an insulating layer on its surface can be preferably used. Since the surface of the substrate on which the light emitting device is mounted coincides with the display surface of the LED display, it may be colored dark brown or black for improving the contrast. Hereinafter, specific examples of the present invention will be described in detail, but it goes without saying that the present invention is not limited thereto.

[0030]

EXAMPLES (Examples 1 to 5) 0.1 mm thick phosphorous copper is pressed and used as an external electrode. This external electrode is molded with a liquid crystal polymer resin. The raw material of this liquid crystal polymer resin is milky white, but 0.4% of carbon black is mixed and it is colored black. The package 102 formed in this way has a thickness of 1 mm and has 3 sides.
mm square. Further, it has an opening (diameter of 2.6 mm) of a concave portion in which the light emitting element is arranged.

LED bare chips 113, 123, 1 are provided as light emitting elements capable of emitting RGB (red, green, blue) light on the lead frame serving as the external electrode 104, respectively.
It was equipped with 33. Light emitting elements 113, 1 capable of emitting BG
In No. 23, a light emitting layer using a gallium nitride based semiconductor was used. As the light emitting element 133 capable of emitting R, a gallium / indium / aluminum / phosphorus semiconductor is used. Each light emitting element was fixed using Ag paste. The light emitting element 133 capable of emitting R is fixed and electrically connected. Since the active layers are formed on the sapphire substrate in the light emitting devices 113 and 123 capable of emitting BG, the gold wires 105 from the same surface side.
Then, the external electrodes were wire-bonded and electrically connected to each other to form a structure as shown in FIG.

Next, a mold member 201 was formed by sealing and curing with epoxy in the package opening. A spherical polymer (benzoguanamine resin, average spherical diameter of about 2 μm) was used as a diffusing agent in an epoxy resin and dispersed and mixed at a weight ratio of 9%. Similarly, only the weight ratio is changed to 1, 3, 6, 12%
Those obtained by dispersing and mixing in Example 2 are also shown in Examples 2, 3, 4, and 5, respectively.
It was formed for use. Each mold member 201 had a thickness of about 1 mm from the end of each light emitting element to the side wall of the package opening, and had a thickness of about 0.2 mm on the light emitting element.

Luminance and contrast ratio as emission characteristics of such a light emitting device were examined by Topcon (BM-7). The front luminance is 823 cd / m 2 when all the RGB are turned on to emit white light, and the dark luminance is 10
It was cd / m2. The dark luminance is measured by arranging an illuminometer in parallel with the light emitting device and irradiating light of 400 lux from the outside. At this time, the contrast ratio is 82:
It is 1.

The RGB light emitting device thus formed was surface-mounted by a chip mounter on a printed board on which a solder cream was printed. This was soldered in a solder reflow furnace to electrically connect each light emitting device and the substrate. In this way, as shown in FIG. 3, an LED display in which 16 × 32 light emitting devices are arranged in a dot matrix with a 4 mm dot pitch can be constructed. A full-color display device can be configured by electrically connecting a substrate on which the light emitting device is arranged and electrically connected to a drive circuit for driving the LED display. (Comparative Example 1) A light emitting device was formed in the same manner as in Example except that the diffusing agent was not added when forming the mold member. Further, similarly, the LED brightness and the dark brightness of the light emitting device were measured. (Comparative Example 2) A light emitting device was formed in the same manner as in Example except that the diffusing agent and the colorant were not added when forming the mold member. Further, similarly, the LED brightness and the dark brightness of the light emitting device were measured. (Comparative Example 3) A light emitting device was formed in the same manner as in Example except that the diffusing agent and the colorant were not added when forming the mold member. Further, similarly, the LED brightness and the dark brightness of the light emitting device were measured. These light emitting devices of Comparative Examples 1 to 3 and Examples 1 to 1
Table 1 shows the results of comparison with the light emitting devices of No. 5 and 5, respectively.
From Table 1, in Example 1, a front luminance of about 1.5 times or more that of Comparative Example 1 was obtained. In contrast, in Example 1, the contrast ratio of Comparative Example 1 was 38: 1, which was extremely high as 82: 1.

[0035]

With the configuration of the present invention, it is possible to configure a display device with good visibility and an optical sensor with less error movement. In particular,
Even if a diffusing agent is contained, the LED brightness can be improved. In addition, the contrast ratio can be improved.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a light emitting device of the present invention.

FIG. 2 is a schematic cross-sectional view showing the operation of the light emitting device of the present invention.

FIG. 3 is a schematic view showing a display device using the light emitting device of the present invention.

FIG. 4 is a diagram showing a relationship between a diffusing agent concentration and front luminance.

FIG. 5 is a schematic cross-sectional view of a light emitting device shown for comparison with the present invention.

[Explanation of symbols]

101 ... Mold member containing diffusing material 102 ... Package 113, 123, 133 ... Light emitting element 104 ... External electrode 105 ... Conductive wire 201 ... Mold member 202 ... Package 211 ... Diffusing material 203 ... Light emitting element 204 ... External electrode 205 ... Electrical connection member 501 ... Mold member 502 ... Package 503 ... Light emitting element 504 ... External electrode 505 ... Electrical connection member

[Table 1]

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[Procedure amendment]

[Submission date] July 8, 2002 (2002.7.8)

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] Full text

[Correction method] Change

[Correction content]

[Document name] Statement

Light emitting device

[Claims]

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display capable of displaying various data, a light emitting device using a light emitting element used for a light source of a line sensor, an optical sensor such as a photo interrupter, and a display device. , Especially a light emitting device with high emission brightness and contrast ratio and high definition using the same,
The present invention relates to a display device capable of high contrast display with a wide viewing angle.

[0002]

2. Description of the Related Art Today, semiconductor light emitting devices capable of emitting light of ultrahigh brightness of 1000 mcd or more are formed in RGB. A light emitting device using such a light emitting element has begun to be used in various fields such as an LED display capable of full color light emission indoors or outdoors and various sensors and indicators. As an example of a light emitting device using such a semiconductor light emitting element, there is a surface mount type LED as shown in FIGS. 5 (A), 5 (B) and 5 (C). The surface mount type LED can be mounted by the chip mounter and the solder reflow like other surface mount type electronic parts such as a chip resistor. The surface-mounted LED can be miniaturized and can be mounted in a relatively high density and with reliability.

In such a light emitting device, a light emitting element 503 is provided on a package 502 formed of various resins such as epoxy resin and liquid crystal polymer, ceramics and the like.
Are arranged and electrically connected to the outside by an external electrode 504. The light emitting element 503 and the external electrode 504 are electrically connected by a conductive wire such as a gold wire or an electrical connection member 505 which is a conductive adhesive using Ag paste. Further, a light-transmitting mold member 501 is provided on the light emitting element 503 to protect it from the external environment. The surface mount type LED has no lens effect or has a small lens effect, and thus can be visually recognized from a wide range and has a wide viewing angle. On the other hand, the front brightness becomes low. Therefore,
As shown in (B) and (C), light emitted from the light emitting element 503 is reflected on the inner surface of the milky white or white package to improve the light emission efficiency. By supplying electric power to such a light emitting device from the outside, the light emitting device can efficiently emit light.

[0004]

However, such a light emitting device cannot be used as a light emitting device having high brightness and high contrast ratio. Specifically, when the light emitting device is used as a display device or an optical sensor, the front luminance when the light emitting device is emitting light and the dark luminance when the light emitting device is not emitting light (outside brightness when the LED is not lit) It is preferable that the difference in the front reflection brightness due to light is large. That is, a display device or the like can emit light of a desired color by turning on the light emitting device. On the other hand, when the light emitting device is not lit, the black color is displayed. Therefore, a clearer image can be displayed by using a display device having a large contrast ratio ((LED front luminance + front reflection luminance) / front reflection luminance), which is the difference between light emission and non-light emission. Similarly, even when the light emitting device is used for the optical sensor, the light emitting device with less malfunction can be obtained.

In order to increase the difference between the time of light emission and the time of non-light emission, the surface of the package other than the light emitting portion on the side of the light emission observation surface is made black, or the package contains a black colorant or the like to improve the contrast. It is possible to earn a ratio.

However, in the case where the surface on the light emission observation surface side is colored in a dark color system, the contrast ratio is not greatly improved because the area of the dark color portion cannot be made large with respect to the area of the package opening in which the light emitting element is mounted. Therefore, even if the surface on the light emitting surface side except the light emitting portion is made to be a dark color system, the contrast ratio is improved from 27/1 to 44/1, and a sufficient contrast ratio cannot be obtained.
Further, the one in which only the surface is colored in a dark color system causes a decrease in the contrast ratio because the side wall portion of the inner wall of the package opening in which the light emitting element is arranged has a high reflectance depending on the viewing angle.

Further, the dark resin area ratio can be increased by coloring the molding resin, etc., which is the package itself, in a dark color system. However, the reflection by the side wall of the inner wall of the package opening can hardly be used. Therefore, LE
D The front brightness is reduced to less than half that of the white molded resin product. The decrease in the front brightness (LED front brightness + dark brightness) becomes too large with respect to the decrease in the dark brightness. for that reason,
Not only the front brightness is lowered, but the contrast ratio is 32 /
It will be about 1. In either case, the light emitting device cannot have a high LED front luminance and a high contrast ratio. Therefore, an object of the present invention is to provide a light emitting device having higher brightness and a higher contrast ratio, and a display device using the same.

[0008]

The present invention is a light emitting device having a light emitting element and a molding member disposed on the light emitting element, wherein the molding member contains a fluorescent substance and a diffusing agent, A light emitting device having a multi-layer structure in which the concentrations of the agents are different.

The invention according to claim 2 of the present invention is the light-emitting device according to claim 1, wherein the concentration of the fluorescent substance in the mold member increases as it approaches the light-emitting element.

In the light emitting device of the present invention, the light emitted from the light emitting element is diffused by the diffusing agent before reaching the side wall of the inner wall of the package opening. Therefore, there is no absorption loss in the side wall of the inner wall of the package opening. On the other hand, the mold member on the light emitting element has a small amount of the diffusing agent, so that diffusion and absorption of light is suppressed. Therefore, it is possible to improve the contrast ratio while suppressing the decrease in LED brightness (reduce the LED brightness decrease rate).

In particular, by coloring the package forming the light emitting device in a dark color such as black, or by printing the light emitting surface side of the light emitting device in black, it is possible to reduce the influence on the reduction of the LED brightness and to remarkably reduce the dark brightness. Can be lowered.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION As a result of various experiments, the present inventor found that the reduction rate of dark brightness and the LE by adding a diffusing agent.
It was found that a light emitting device which can emit light with higher contrast and higher brightness can be obtained by utilizing the difference in the reduction rate of D brightness, and the present invention has been accomplished.

That is, there is a case where a light emitting diode such as a shell type is usually made to contain a diffusing agent to cause a diffusing effect. However, if a light diffusing material is contained in such a light emitting diode, the light emission brightness is reduced. The present invention has found that even if a diffusing material is contained in a specific mold member or package, the light emission brightness from the LED is conversely improved. In the light emitting device of the present invention, by including a diffusing agent in the mold member, the LED luminance reduction rate (LED is lower than the dark luminance reduction rate (the rate of reduction of the front reflection luminance due to the external light when the LED is not lit)). The ratio of the decrease in the front brightness of the light emitting device is small, and the light emitting device has a high light emitting brightness and a high contrast.

More specifically, as shown in FIG. 2, the light emitting element 203 is arranged in the concave portion of the package 202 formed of liquid crystal polymer or the like. An external electrode 204 is provided on the package 202 so that it can be electrically connected to the outside. The electrode of the light emitting element 203 and the external electrode 204 are
Each is electrically connected by a conductive wire 205 such as a gold wire. In addition, a light-transmitting mold member 201 is provided on the light emitting element 203 to protect the semiconductor from the external environment.
Is provided. Particularly, in the present invention, carbon black is contained in the resin forming the package 202 in order to improve the contrast ratio rather than using the reflection from the light emitting element by the inner wall of the package opening, and a dark color system such as black or gray is used. It is packaged. On the other hand, in the mold member, the diffusing agent 211 is included in consideration that the inner wall of the package opening is also a dark color system and the use of reflection on the inner wall of the package opening cannot be expected. This diffusing agent 2
The inclusion of 11 diffuses the light emitted from the light emitting element toward the inner wall of the package opening as shown by the arrow in FIG. Further, the mold member is arranged on the light emitting element, but since the mold member is thin with respect to the distance to the inner wall of the package opening, absorption and scattering of light is small. Therefore, the reduction of the light emission brightness is suppressed. Hereinafter, each configuration of the present invention will be described in detail. (Mold Member 101, 201) The mold member 201 of the present invention is provided to protect each light emitting element 203 and wires for electrical connection thereof from external force, dust, water and the like. Further, in order to improve the dark brightness while effectively extracting the light from the light emitting element 203, the diffusing agent 211 is used.
Is included. The mold member 201 is made of the diffusing agent 21.
1 by containing 1 than the dark brightness reduction rate LED
As long as the reduction rate of the front luminance is small, it may be formed in one layer, or may be formed in two or more layers as desired, such as a multilayer structure in which the concentration of the diffusing agent 211 and the refractive index are different. Similarly, not only the cross-sectional shape, but also a multi-layer structure having different diffusion concentrations such as increasing annually the concentration of the diffusing agent as seen from the side of the emission observation surface can be adopted. Such a mold member 20
Specific examples of the material of No. 1 are organic members made of resin having excellent weather resistance such as epoxy resin, urea resin, silicon resin, fluororesin, polycarbonate resin, and SiO ₂ ,
An inorganic member such as Al ₂ O ₃ is preferably used. In a use environment where the temperature cycle is severe, it is more preferable that the mold member has a thermal expansion coefficient close to that of the package or the like.

Further, the mold member 2 constituting the light emitting device.
01 contains various additives such as a colorant, a light stabilizer and a fluorescent substance, if desired, as long as the LED front luminance reduction rate is smaller than the dark luminance reduction rate by including the diffusing agent 211. You can also This makes it possible to adjust the light emission peak from the light emitting element 203 and reduce the directivity to increase the viewing angle. In addition, a light emitting device having a desired emission wavelength can be used. Further, the light emitting device can be more weather resistant even when used outdoors.

The colorant is contained in the mold member 201 and has a filter effect for cutting out an undesired wavelength of the light emitted by the light emitting element 203 to improve the light emitting characteristics. Therefore, various dyes and / or pigments are variously selected according to the emission color of the light emitting device (main emission wavelength which is the main peak of emission).

Since the light emitted from the light emitting element 203 has a monochromatic peak wavelength, it is possible to form a light emitting device displaying a white color by combining it with a fluorescent substance or the like. In this case, by using a blue gallium nitride-based compound semiconductor with a large emission wavelength energy and a ytrim / aluminum oxide-based fluorescent material added with cerium or a fluorescent material that is a perylene-based derivative, it is possible to achieve high brightness efficiently. It can emit light.

Further, in addition to the diffusing agent used in the present invention, a colorant, a light stabilizing member, a fluorescent substance, etc., which can be contained, are dispersed in the mold member at various ratios to be formed. Is also good. That is, the content concentration can be increased or decreased as it approaches the light emitting element, and various selections can be made. (Diffusing Agent 211) The diffusing agent 211 contained in the mold member 201 reduces the scattering absorption of the light emitted from the light emitting element 203 and is emitted to the light emission observation surface side, and is diffused to the inner wall side of the opening in the package. By scattering a large amount of directed light, the emission brightness of the light emitting device is improved. Also,
By adjusting the content of the diffusing agent 211, the dark brightness of the package opening in which the light emitting element 203 is arranged can be adjusted. As such a diffusing agent 211, an inorganic member such as barium titanate, titanium oxide, aluminum oxide or silicon oxide, or an organic member such as melamine resin, CTU guanamine resin or benzoguanamine resin is preferably used.

In order to show the effect of the present invention, the relationship with the concentration of the diffusing agent using the organic member benzoguanamine resin as the mold member 201 arranged in the package colored black with car black as a dark color system is shown in FIG. Shown in.

From FIG. 4, if the dispersion concentration of the diffusing agent increases,
The front brightness of the light emitting device increases. This is because the light emitted from the light emitting element goes not only in the front direction of the emission observation but also in the inner wall direction of the package opening, so that the lost light absorbed by the side wall is guided to the front side due to scattering of the diffusing material. Conceivable. Also, if the diffusing agent concentration is too high,
On the contrary, the front brightness starts to decrease. It is considered that this is because the ratio of direct light scattered from the LED chip, which is a light emitting element, increases, and the increase in front luminance reaches a ceiling. Further, it is considered that as the concentration of the diffusing agent increases, the effect of external light entering is scattered and reflected, and the effect of lowering the dark brightness is imparted. It has been confirmed that almost the same tendency can be obtained with other inorganic materials.

Particularly, when the LED display is viewed indoors or outdoors, there is a possibility that various external light such as sunlight may enter. Therefore, the dark brightness of the LED display should be sufficiently reduced and the contrast ratio should be 50 or more. For example, visibility is extremely reduced due to external light reflection. Therefore, the concentration of the diffusing agent depends on the material etc.
-12% is preferable. This optimizes the increase in frontal brightness. Further, the diffusing agent can prevent external light from directly reaching the external electrodes or the like provided on the bottom surface of the package, or even when reaching the external electrodes or the like, reflection and scattering to the outside can be suppressed. Therefore, it is possible to strengthen the tendency for the dark luminance to decrease. Thereby, the contrast ratio can be optimized to 50 or more. Further, a spherical polymer or the like can be suitably used in a range of 0.1 to 20 μm, but if it is too small, the dispersibility is poor, and if it is too large, it tends to settle out easily, so 1 to 5 μm is more preferable. The concentration of this diffusing agent is one or more orders of magnitude higher than the concentration of diffusing that is normally used in bullet-type light emitting diodes. Since the thickness of the mold member on the light emission observation surface side is made thin, even if it is contained by one digit or more, the decrease in the front luminance of the LED can be small. (Packages 102, 202) The package 202 has an external electrode 204 for fixing and protecting the light emitting element 203 in the concave portion and capable of being electrically connected to the outside. Therefore, the package 202 having a plurality of openings can be formed according to the number and size of the light emitting elements 203. Further, preferably, in order to have a light-shielding function, it is colored in a dark color system such as black or gray, or the light emission observation surface side of the package is colored in a dark color system. Package 2
02 is provided with a mold member 201 which is a translucent protector in order to further protect the light emitting element 203 from the external environment.
The package 202 preferably has good adhesiveness to the mold member 201 and higher rigidity than the mold member. In order to improve the adhesiveness with the mold member 201 and to direct the force that acts from the mold member 201 during thermal expansion to the outside, it is preferable that the cylindrical portion has a slanted shape that expands toward the outside. Further, it is desired to have an insulating property in order to electrically shut off the light emitting element 203 and the outside. Furthermore, when the package 202 is affected by heat from the light emitting element 203 or the like, it is preferable that the package 202 has a small coefficient of thermal expansion in consideration of adhesion with the mold member 201. Package 2
The inner surface of the concave portion of 02 may be embossed to increase the adhesion area, or plasma-treated to improve the adhesion to the mold member 201. Package 202 is
The external electrode 204 may be formed integrally with the external electrode 204, or the package 202 may be divided into a plurality of parts and combined by fitting or the like. Such a package 202
Can be formed relatively easily by insert molding or the like.

As such a packaging material, polycarbonate resin, polyphenylene sulfide (PP
S), liquid crystal polymer (LCP), ABS resin, epoxy resin, phenol resin, acrylic resin, resin such as PBT resin, or ceramics can be used. Various dyes and pigments are preferably used as the colorant for coloring the package 202 in a dark color system. Specifically, Cr
Preferable examples include ₂ O ₃ , MnO ₂ , Fe ₂ O ₃ and carbon black.

The light emitting element 203 and the package 202 can be adhered to each other with a thermosetting resin or the like. Specifically, an epoxy resin, an acrylic resin, an imide resin, or the like can be given. Further, in order to fix the light emitting element 203 and to electrically connect it to the external electrode 204 in the package 202, Ag paste, carbon paste,
Metal bumps or the like can be used. (External Electrodes 104, 204) The external electrodes 204 are used to supply electric power from the outside of the package 202 to the light emitting element 203 arranged inside. Therefore, various ones such as those using a conductive pattern provided on the package or a lead frame can be used. Further, the external electrode 204 can be formed in various sizes in consideration of heat dissipation, electrical conductivity, characteristics of the light emitting element 203, and the like. The external electrode 204 preferably has good thermal conductivity in order to dispose the light emitting elements 203 and to radiate the heat emitted from the light emitting elements 203 to the outside. The specific electric resistance of the external electrode 204 is preferably 300 μΩ · cm or less, and more preferably,
It is 3 μΩ · cm or less. Also, the specific thermal conductivity is
It is preferably 0.01 cal / cm ² / cm / ° C or higher, more preferably 0.5 cal / cm ² / cm / ° C or higher. As such an external electrode 204, a copper or phosphor bronze plate whose surface is plated with a metal such as silver, palladium or gold or a solder plating is preferably used. When a lead frame is used as the external electrode 204, it can be used in various ways depending on electrical conductivity and thermal conductivity, but a plate thickness of 0.1 mm to 2 mm is preferable from the viewpoint of workability. As the external electrode 204 provided on a substrate such as glass epoxy resin or ceramic, a copper foil or a tungsten layer can be formed. When a metal foil is used on the printed board, the thickness of the copper foil or the like is preferably 18 to 70 μm. Further, gold, solder plating or the like may be applied on the copper foil or the like. (Light-Emitting Element 113, 123, 133, 203) As the light-emitting element 203 used in the present invention, a liquid phase growth method or M
InN, AlN, GaN, etc. are formed on the substrate by the OCVD method or the like.
ZnS, ZnSe, SiC, GaP, GaAs, GaA
lAs, GaAlN, AlInGaP, InGaN, A
A material in which a semiconductor such as lInGaN is formed as a light emitting layer is preferably used. Examples of the semiconductor structure include a MIS junction, a homo structure having a PIN junction or a PN junction, a hetero structure, or a double hetero structure. The emission wavelength can be variously selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the mixed crystallinity thereof. Furthermore, in order to have a quantum effect, the light emitting layer may have a single quantum well structure or a multiple quantum well structure.

The semiconductor thus formed is subjected to a vacuum deposition method, heat,
A desired electrode is formed by using various CVD methods utilizing light, discharge energy and the like. The electrodes of the light emitting element 204 may be provided on one side of the semiconductor or on both sides thereof. Directly full cut the semiconductor wafer on which the electrode is formed with a dicing saw with a blade having a diamond blade tip, or after cutting a groove with a width wider than the blade edge width (half cut), the semiconductor wafer is cut by an external force. Break. Alternatively, an extremely thin scribe line (meridian line) is drawn on the semiconductor wafer by, for example, a grid pattern by a scriber in which the diamond needle at the tip moves reciprocally in a straight line, and then the wafer is split by external force to cut the semiconductor wafer into chips and emit light. An LED chip, which is an element, can be formed.

In order to allow the light emitting device to emit full-color light, an LED chip that emits RGB light emission colors can be used. In particular, when using outdoors, it is preferable to use gallium nitride-based compound semiconductors for green and blue as a high-luminance semiconductor material, and gallium / aluminum / arsenic or aluminum / indium / gallium / phosphorus for red. Although it is preferable to use a system semiconductor, various types can be used depending on the application.

In order to use a light emitting element capable of emitting RGB light as a light emitting device capable of full color light emission, the red emission wavelength is from 600 nm to 700 nm.
It is preferable to use an LED chip that uses a semiconductor having a green wavelength of 495 nm to 565 nm and a blue wavelength of 400 nm to 490 nm. (Electrical Connection Members 105, 205) Electrical Connection Member 20
5, the ohmic property with the electrode of the light emitting element 203,
Good mechanical connectivity, electrical conductivity, and thermal conductivity are required. When a conductive wire is used, the thermal conductivity is preferably 0.01 cal / cm ² / cm / ° C or higher, more preferably 0.5 cal / cm ² / cm / ° C or higher. The diameter of the conductive wire is preferably Φ10 μm or more and Φ45 μm or less in consideration of workability and the like. Specific examples of such a conductive wire include a conductive wire using a metal such as gold, copper, platinum, or aluminum, or an alloy thereof. Such a conductive wire can easily connect the electrode of each light emitting element 203 and the external electrode 204 etc. by a wire bonding device.

When a conductive paste is used, it can be used by incorporating conductive C, ITO, ZnO, Ag, metal bumps, etc. into a desired resin such as an epoxy resin. By using such a conductive paste, not only electrical conduction but also fixing of the light emitting element 203 can be achieved. (Substrate) A substrate is preferably used for arranging each light emitting device in a desired shape such as a matrix and electrically connecting them. Such a substrate may be used not only for disposing the light emitting device but also as a substrate for a drive circuit. Therefore, it is preferable that the substrate has high mechanical strength and little thermal deformation. Specifically, ceramics on which a conductive pattern such as a tungsten layer is formed, glass epoxy resin on which a conductive pattern such as a copper foil is formed, and a metal or an alloy having an insulating layer on its surface can be preferably used. Since the surface of the substrate on which the light emitting device is mounted coincides with the display surface of the LED display, it may be colored dark brown or black for improving the contrast. Hereinafter, specific examples of the present invention will be described in detail, but it goes without saying that the present invention is not limited thereto.

[0027]

EXAMPLES (Examples 1 to 5) 0.1 mm thick phosphorous copper is pressed and used as an external electrode. This external electrode is molded with a liquid crystal polymer resin. The raw material of this liquid crystal polymer resin is milky white, but 0.4% of carbon black is mixed and it is colored black. The package 102 formed in this way has a thickness of 1 mm and has 3 sides.
mm square. Further, it has an opening (diameter of 2.6 mm) of a concave portion in which the light emitting element is arranged.

LED bare chips 113, 123, 1 are provided as light emitting elements capable of emitting RGB (red, green, blue) light on the lead frame serving as the external electrode 104, respectively.
It was equipped with 33. Light emitting elements 113, 1 capable of emitting BG
In No. 23, a light emitting layer using a gallium nitride based semiconductor was used. As the light emitting element 133 capable of emitting R, a gallium / indium / aluminum / phosphorus semiconductor is used. Each light emitting element was fixed using Ag paste. The light emitting element 133 capable of emitting R is fixed and electrically connected. Since the active layers are formed on the sapphire substrate in the light emitting devices 113 and 123 capable of emitting BG, the gold wires 105 from the same surface side.
Then, the external electrodes were wire-bonded and electrically connected to each other to form a structure as shown in FIG.

Next, the mold member 201 was formed by sealing and curing with epoxy in the package opening. A spherical polymer (benzoguanamine resin, average spherical diameter of about 2 μm) was used as a diffusing agent in an epoxy resin and dispersed and mixed at a weight ratio of 9%. Similarly, only the weight ratio is changed to 1, 3, 6, 12%
Those obtained by dispersing and mixing in Example 2 are also shown in Examples 2, 3, 4, and 5, respectively.
It was formed for use. Each mold member 201 had a thickness of about 1 mm from the end of each light emitting element to the side wall of the package opening, and had a thickness of about 0.2 mm on the light emitting element.

Luminance and contrast ratio as emission characteristics of such a light emitting device were examined by Topcon (BM-7). The front luminance is 823 cd / m ² when all RGB are turned on and white light is emitted, and the dark luminance is 10
It was cd / m ² . The dark luminance is measured by arranging an illuminometer in parallel with the light emitting device and irradiating light of 400 lux from the outside. At this time, the contrast ratio is 82:
It is 1.

The light-emitting device capable of emitting RGB light thus formed was surface-mounted by a chip mounter on a printed board on which a solder cream was printed. This was soldered in a solder reflow furnace to electrically connect each light emitting device and the substrate. In this way, as shown in FIG. 3, an LED display in which 16 × 32 light emitting devices are arranged in a dot matrix with a 4 mm dot pitch can be constructed. A full-color display device can be configured by electrically connecting a substrate on which the light emitting device is arranged and electrically connected to a drive circuit for driving the LED display. (Comparative Example 1) A light emitting device was formed in the same manner as in Example except that the diffusing agent was not added when forming the mold member. Further, similarly, the LED brightness and the dark brightness of the light emitting device were measured. (Comparative Example 2) A light emitting device was formed in the same manner as in Example except that the diffusing agent and the colorant were not added when forming the mold member. Further, similarly, the LED brightness and the dark brightness of the light emitting device were measured. (Comparative Example 3) A light emitting device was formed in the same manner as in Example except that the diffusing agent and the colorant were not added when forming the mold member. Further, similarly, the LED brightness and the dark brightness of the light emitting device were measured. These light emitting devices of Comparative Examples 1 to 3 and Examples 1 to 1
Table 1 shows the results of comparison with the light emitting devices of No. 5 and 5, respectively.
From Table 1, in Example 1, a front luminance of about 1.5 times or more that of Comparative Example 1 was obtained. In contrast, in Example 1, the contrast ratio of Comparative Example 1 was 38: 1, which was extremely high as 82: 1.

[Table 1]

[0032]

With the configuration of the present invention, it is possible to configure a display device with good visibility and an optical sensor with less error movement. In particular,
Even if a diffusing agent is contained, the LED brightness can be improved. In addition, the contrast ratio can be improved.

[Brief description of drawings]

FIG. 1 is a schematic plan view of a light emitting device of the present invention.

FIG. 2 is a schematic cross-sectional view showing the operation of the light emitting device of the present invention.

FIG. 3 is a schematic view showing a display device using the light emitting device of the present invention.

FIG. 4 is a diagram showing a relationship between a diffusing agent concentration and front luminance.

FIG. 5 is a schematic cross-sectional view of a light emitting device shown for comparison with the present invention.

[Explanation of symbols] 101 ... Mold member containing diffusing material 102 ... Package 113, 123, 133 ... Light emitting element 104 ... External electrode 105 ... Conductive wire 201 ... Mold member 202 ... Package 211 ... Diffusing material 203 ... Light emitting element 204 ... External electrode 205 ... Electrical connection member 501 ... Mold member 502 ... Package 503 ... Light emitting element 504 ... External electrode 505 ... Electrical connection member

Continued front page    (72) Inventor Hayato Takeuchi             100, 491, Oka, Kaminaka-cho, Anan City, Tokushima Prefecture             Gaku Kogyo Co., Ltd. F-term (reference) 5F041 AA10 AA14 DA07 DA14 DA19                       DA36 DA43 DA55 FF01

Claims (5)

[Claims] 1. A light emitting device disposed in a package recess,
A light emitting device having a mold member disposed on the light emitting element arranged in the recess, wherein L is lower than a dark luminance reduction rate of the light emitting device in the mold member.
A light-emitting device comprising a diffusing agent that reduces the ED luminance reduction rate. 2. The light emitting device according to claim 1, wherein the light emitting element is at least three types of semiconductor light emitting elements capable of emitting RGB light. 3. A light emitting device having a light emitting element arranged in a recess of a package and a mold member for protecting the light emitting element, wherein the package is formed from the light emitting element rather than the thickness of the mold member on the light emitting element. A light emitting device, wherein a thickness up to a side surface is larger and a diffusing agent is contained in the mold member. 4. The light emitting device according to claim 3, wherein a dark colorant is contained in the package and / or on the light emitting surface side surface of the package. 5. A display device comprising surface-mounted LEDs arranged in a dot matrix and driving means for driving the surface-mounted LEDs, wherein the surface-mounted LED package is a dark color system. A display device characterized by being sealed with a mold member in which a diffusing agent is dispersed in a package concave opening in which a light emitting element is mounted.