JP3204294B2 - LED display - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an LED display using a plurality of light emitting diodes, and more particularly, to an LED display in which a display pattern or color mixing does not change significantly even when a part of the light emitting diodes is turned off.

[0002]

2. Description of the Related Art Today, RGB high-intensity light emitting diodes have been developed and used for various LED displays. Such LED indicator, very long lifetime compared to the bulb, because the a and efficient advertising,
It has been used for displaying destination information and road information, for signaling, and the like. An LED display using a light-emitting diode can display a sentence by making the LED display correspond to one character, or display an image handled as one dot. The LED display is formed using a plurality of light emitting diodes. Therefore, it is desired that the display shape of the LED display does not significantly change even when a part of the light emitting diodes constituting the LED display is turned off. JP-A-5-102 discloses such an LED display.
No. 525 and the like.

[0003] On the other hand, a traffic signal is cited as a display device. Traffic lights using light bulbs use reflectors to increase the degree of light collection. Such a reflection plate reflects through a color filter when direct sunlight is applied to the display unit even if a light-blocking member is provided. For this reason, there is a problem in that the light reflected by the reflector appears to be quasi-lit through the color filter, even though the signal in the traveling direction is turned off on a west day or the like. In addition, maintenance-free, in which the number of light emitting unit replacements is small, is a very important factor for a traffic signal in consideration of workability and the like. However, although the signal bulb is used at a voltage of 80% to 90% of the rated voltage and extends its life to about 5000 hours, the voltage is reduced by nearly 12% by the decrease of 1V. For this reason, between the use phase of the signal for the light bulb has decided to use limit so as not to exceed two years. For the stop signal of high importance, 7
They have been replaced in about a month. Therefore, there is a problem that a bulb having a very short life as compared with a light emitting diode must be replaced frequently.

As means for solving such a problem, an LED display utilizing a light emitting diode is disclosed in Japanese Patent Laid-Open No. 5-101.
298 and JP-A-6-219279. LE with multiple light emitting diodes instead of light bulbs
Since all the light emitting diodes of the D display have excellent light emitting characteristics, white light cannot be emitted by using only one kind of LED chip. In the case of using a white traffic signal such as a railway signal, a plurality of light emitting diodes must be combined and mixed to emit white light. Therefore Tei is an LED indicator with a plurality of light-emitting diodes in such complementary relationship
You . Further, although the life of the light emitting diode is long, in a severe outdoor use environment, when a plurality of light emitting diodes are used for a long time, some of the characteristics may be deteriorated. In such a case, an LED display such as a traffic light, for which it is particularly important to maintain reliability, treats light emitting diodes as a group and connects them in parallel. Thus, even if one of the light emitting diode groups connected in parallel is turned off due to disconnection or the like, the function of the traffic light can be prevented from being reduced by the other circuit.

[0005]

However, when light is emitted by a partial light emitting diode, such as when one of the light emitting diodes is turned off, if the shape and chromaticity of the light emitting surface change, it functions as an LED display such as a traffic light. do not do. In particular, it has been extremely difficult and not sufficient to satisfy the uniformity of the display surface and the color mixing at the same time when the conventional LED display is partially turned off.

Accordingly, in view of the above-mentioned problems, the present invention provides an LE that does not greatly reduce the display shape and color mixing even if some of the light emitting diodes used in the LED display are turned off.
D display.

[0007]

The present invention provides a light emitting diode group in which at least two kinds of light emitting diodes having different emission wavelengths are connected in series on a substrate, and an LED display in which two or more light emitting diode groups are connected in parallel. there are, substantially spiral between the light emitting diode group and the first light emitting diode groups arranged in a substantially spiral shape, the first light emitting diode group
A second group of light emitting diodes arranged in a matrix.
It is an ED display. Further, one of the light emitting diodes having different emission wavelengths is an LED display which has higher visibility than the other and is arranged substantially symmetrically with the center of the LED display.
Further, the present invention is also an LED display in which light-emitting diodes having lower luminosity than light-emitting diodes having different emission wavelengths are arranged along the outermost periphery of the display surface of the LED display.

[0008] Further, there is provided an LED display having a plurality of light emitting diode groups connected in parallel on a substrate, wherein the first light emitting diode group is arranged at least in a spiral shape.
And a second light emitting diode group spirally arranged between the first light emitting diodes arranged in the first spiral shape. Each of the light emitting diode groups has two or more types. It is also an LED display that expresses colors by color mixture using light emitting diodes. Further, the light emitting diode group is a light emitting diode using a gallium nitride-based semiconductor and a light emitting diode using indium, gallium, aluminum, and an arsenic-based semiconductor connected in series, and the gallium nitride-based semiconductors are connected in parallel. The connected LED display.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The present inventor has conducted various experiments,
In an LED display using a plurality of light emitting diodes,
The inventors of the present invention have found that the deformation of the light-emitting display shape and the reduction in color mixing properties, such as when the light is partially turned off, can be greatly improved by the specific arrangement of the light-emitting diodes.

That is, light-emitting diodes in which two or more types of light-emitting diodes are connected in series are treated as a group and are connected in parallel. The light emitting diode groups are arranged in a substantially spiral shape that draws a ring from the center toward the outside. As for the display surface, a plurality of arrangements such as spirals are combined, and all the light emitting diodes are arranged over the entire light emitting display surface of the LED display. Thereby, even if one of the light emitting diode groups is turned off, the display shape is not largely distorted and the color mixing property is not greatly reduced. Since two or more types of light emitting diodes are arranged in a substantially spiral shape as a light emitting diode group, it is easy to adjust the distance between the respective light emitting diodes, and it is possible to dispose the LED on the entire surface of the LED device and to obtain a good color mixture.
It can be a D display. Further, it is possible to provide an LED display in which the color mixing property for each light emitting diode group and the color mixing property when all the light emitting diode groups are turned on are improved. Further, by arranging the light-emitting diodes having lower luminosity on the outer periphery of the LED display for each light-emitting diode group, it is possible to obtain an LED display device having more excellent color mixing. Hereinafter, the present invention will be described in detail with reference to the drawings.

On a printed circuit board on which four layers of copper foil patterns are formed, four kinds of spiral wiring through holes are provided so that light emitting diode groups connected in parallel to each other can be formed. The printed circuit board has a light-emitting diode that can emit yellow light in each spiral light-emitting diode group and a light-emitting diode that can emit blue-green light with higher luminosity, which is complementary to the light-emitting diode, taking color mixing into account. 7: 4
Are arranged on the entire display surface as shown in FIG. The light-emitting diodes capable of emitting blue-green light are each connected in parallel between two blue-green light-emitting diodes using a gallium nitride-based semiconductor. The yellow light emitting diode and the blue green light emitting diode are connected in series for each light emitting diode group. Emitting diode formed on the substrate, 4及 beauty filler to a position beneath the disposed cross-sectional views in a housing having a light-shielding member as shown in FIG. 5 LED chip is injected filled into close contact. In front of the housing, a diffusion lens is used to further mix the light of each light emitting diode. A cord led out of the board and connected to an external power supply is discharged through a packing on the back side of the housing. Hereinafter, each configuration of the present invention will be described in detail.

(Light emitting diodes 101, 102, 201, 202, 2
03, 204) As the light-emitting diode used in the present invention, light-emitting elements using various semiconductors are suitably used. Specifically, GaAl is formed on a substrate by a liquid phase growth method, an MOCVD method, or the like.
N, ZnS, ZnSe, SiC, GaP, GaAlA
s, AlInGaP, InGaN, GaN, AlInG
A semiconductor in which a semiconductor such as aN is formed as a light emitting layer is used. MIS junction, PIN junction
Homo structure and having a pn junction, include the hetero structure to heterostructure or double. The emission wavelength can be variously selected from ultraviolet light to infrared light depending on the material of the semiconductor layer and the degree of mixed crystal thereof. Further, the light emitting layer may have a single quantum well structure or a multiple quantum well structure in order to have a quantum effect.

[0013] LED in a place where external light is relatively strong such as outdoors
When a display is used, it is preferable to use a gallium nitride-based compound semiconductor for the green and blue colors. Also,
Red and gallium in yellow, aluminum, arsenic based semiconductor or a aluminum, in Ji arm, gallium, it is preferable to use a semiconductor phosphorus. When displaying white as LED indicator, a light emitting diode having a blue-green gallium nitride-based compound semiconductor, yellow aluminum, in Ji arm, gallium, be a light emitting diode having a phosphorus-based compound semiconductor preferably .

The light emitting diode may be used as it is when the casing has a high hermeticity, but the LED chip may be protected with a resin or the like. In order to protect the LED chip with resin etc., fix the LED chip on the cup of the mount lead, and connect both the positive and negative electrodes or one electrode of the LED chip and the inner lead etc. to the conductive material such as gold wire, platinum or aluminum wire. Electrically connected by a conductive wire. If only the electrodes of one polarity without using a conductive wire, a fixed LED chip _{Ag, C, ITO, Sn O} 2
Which conductive material may take the electrical connection including a mount lead with affixing such a conductive paste obtained by mixing a resin binder Do. Next, it is also possible to form a light emitting diode by coating the electrically conductive one with a mold member for protecting the LED chip and a metal wire for electrical connection thereof from external force, moisture and the like. it can.

The mold member can contain a diffusing agent, a coloring agent, a fluorescent substance, and the like, as desired. Thus, the viewing angle can be increased by adjusting the emission peak from the LED chip or by relaxing the directivity. Further, a light emitting diode having a desired light emission wavelength can be used. Specifically, a single LE can be formed by mixing a phosphor emitting a yellow light or a phosphor emitting a red light with a phosphor emitting a green light in a blue-green light emitting diode.
Using the D chip, white light that cannot be emitted can be displayed.

By forming the resin mold into a desired shape, it is possible to have a lens effect of converging or diffusing light emitted from the LED chip. Therefore,
The resin mold may have a laminated structure. Specifically, the shape is a convex lens shape, a concave lens shape, or a combination thereof. Also, the shape of the light emitting diode viewed from the light emission observation surface side can be variously formed such as a true circle, an ellipse, and a square depending on the purpose. As the material of the mold member, 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. The colorant is included in the mold member so as to cut off an undesired wavelength out of the light emitted by the LED chip to provide a filter effect of improving the light emission characteristics. Therefore, various dyes and / or pigments are variously selected according to the emission color of the light emitting diode (main emission wavelength which is the main peak of the emission light). Further, the colorant may be dispersed and formed at various ratios in the mold member as desired. That is, the concentration can be increased or decreased as the LED chip is approached, and various choices can be made. Such a mold member is formed by mixing and stirring a colorant or the like in the raw material of the mold member, and then forming the mold member into a desired shape such as a shell shape.
It can be formed by putting together with an ED chip and curing.

In order to use an LED as a full-color display, a red light emission wavelength is 600 nm to 700 nm and a green light including blue-green is 495 as an RGB light source.
It is preferable to use an LED chip using a semiconductor having a wavelength of 565 nm to 565 nm and a blue light emission wavelength of 430 nm to 490 nm.

(Substrate 103) As the substrate, it is preferable that a plurality of light-emitting diodes be divided into groups, arranged in a spiral shape forming a ring from the center to the outside, and electrically connected. In the present invention, the drawing of a ring from the center to the outside includes both a drawing of a continuous ring and a drawing of a ring intermittently. Further, the spiral shape means that the LED display is substantially arranged on a continuous line that draws a ring from the center of the emission observation surface of the LED display toward the outside.
Therefore, it is possible to variously select the number of light emitting diodes and the number of light emitting diode groups arranged according to the display area of the LED display. In addition, depending on the type of light emitting diode selected, the brightness and the visibility, a spiral shape with good color mixing can be obtained from a spiral line within 30% of an adjacent line.

The spiral second light emitting diode group may be alternately arranged on the spiral of the first light emitting diode group with the light emitting diode of the first light emitting diode group. The second light emitting diode group may be spirally arranged between the spiral lines. The light emitting diode groups are connected in series and / or series / parallel, and the light emitting diode groups are connected in parallel. This allows
Even if one of the light emitting diode groups or some light emitting diodes are turned off due to some trouble, the other light emitting diode group or the remaining light emitting diodes can emit light.

When mixed color display is performed by using light emitting diodes having two or more kinds of light emission wavelengths, although it depends on light emission luminance,
It is preferable to arrange a smaller number of light emitting diodes with higher visibility. Furthermore, by arranging light emitting diodes with higher visibility at the center symmetry of the LED display,
The color mixing property of each light emitting diode group can be further improved. (Note that the central symmetry in the present invention means L
When the display surface of the ED display is converted into a perfect circle, it is symmetrically arranged from the center point, and each position is within 15% of the distance from the center. )

It is preferable that the light emitting diode having higher visibility is not located at the center of the LED display. The central part also corresponds to the central part of the condenser lens used for the housing. Therefore, the light emitting diode having high visibility is conspicuous, and the color mixing property is reduced. Similarly, it is preferable to dispose a light-emitting diode with lower visibility at a portion corresponding to the light-emitting region of the LED display. When a light-emitting diode with high visibility is arranged at the outermost part, there is no color mixture with the outside, so that the region is conspicuous, and a region where color mixture does not occur partially is formed. This reduces the color mixing. Therefore, it is preferable to arrange light emitting diodes with low visibility on the outer periphery of the display unit for each light emitting diode group.

When the light emitting diodes of the LED display in consideration of the color mixing are formed in a spiral shape, a relatively simple circuit design can be made, but the electrical connection between the light emitting diodes is still complicated. Therefore, it is preferable to use a substrate in which three or more conductive patterns are stacked via an insulator. By forming this conductive pattern for each layer, even if a plurality of light emitting diode groups and light emitting diodes having two or more different emission wavelengths are used, the light emitting diodes can be freely arranged and wired on the substrate. . Further, heat from the light emitting diode can be efficiently released using the conductive pattern. That is, an increase in the temperature of the light emitting diode may cause a shift in emission wavelength or a decrease in luminance. Furthermore, the life of the light emitting diode may be significantly reduced. In particular, when the light emitting diodes are arranged close to each other in order to improve color mixing, it is necessary to consider the influence of heat generated from the light emitting diodes. Therefore, it is preferable to dissipate heat from the light emitting diode using the conductive pattern of the multilayer substrate on which the conductive pattern is formed. Specifically, the heat radiation portion is formed by setting the conductive pattern on the outermost surface (backmost surface) side of the substrate on which the light emitting diodes are arranged and connected to a larger area than other conductive patterns. The connection between the conductive pattern and the light emitting diode can be made with a lead frame of the light emitting diode using solder or the like. The connection between the heat radiating portion of the conductive pattern and the lead frame of the light emitting diode can be a mount lead and / or an inner lead. Since the heat from the LED chip is directly conducted to the mount lead on which the LED chip is mounted, it is more preferable to increase the area of the conductive pattern connected to the lead in order to improve heat dissipation. In order to increase the area of the conductive pattern, it is preferable to use a layer of a conductive pattern different from the conductive pattern electrically connected to the light emitting diode. Thereby, the electrically independent conductive pattern can arrange the heat radiation area freely and freely.

The substrate 103 on which the light emitting diodes are arranged may be used not only for the arrangement of the light emitting diodes but also for the substrate for the driving circuit. The substrate is preferably one having high mechanical strength and low thermal deformation. Specifically, a substrate using ceramics, glass, or the like on which a conductor such as a copper foil is formed can be suitably used. Since the surface of the substrate on which the light emitting diodes are mounted coincides with the display surface of the LED display, it is preferable that the surface be colored dark brown or black to improve the contrast. In addition, unevenness may be applied to improve the adhesion to the filler.

(Filler 501) The filler 501 is required to have good adhesion to the light emitting diode, the housing 402, the substrate on which the light emitting diode is disposed, and the like. In addition, the filler 501 is required to have mechanical strength and work efficiency for protecting the electric circuit to which the light emitting diode is connected. Such a filler 5
01, specifically, an epoxy resin, a urethane resin,
Silicon resin and the like can be mentioned. In particular, a naturally curable silicone rubber is more preferable as having excellent weather resistance. The filler 501 is provided on the display surface side of the LED display. Therefore, a dye and / or a pigment such as dark brown or black may be contained in the filler for the purpose of improving the contrast. Further, a heat conductive member may be included in the filler for the purpose of radiating heat from the light emitting diode. Since the heat conducting member is disposed between the light emitting diodes, it is required that the heat conducting member does not conduct electricity. Specific examples include copper oxide, silver oxide and titanium oxide.

(Case 402) The case 402 used in the present invention is a material for mechanically protecting each light emitting diode arranged in a spiral shape on a substrate from the outside, and has a desired size and Various shapes can be formed. The housing 402 may be provided with a light-blocking member in order to reduce the influence of extraneous light applied to the light-emitting diode. The housing may be formed integrally with the light-shielding member, or from the viewpoint of workability, the light-shielding member and the housing may be separately formed, and after the housing is installed, the light-shielding member may be combined to improve productivity. May be. In addition, the angle of the light blocking member can be changed in various ways to improve the visibility. Further, the light-shielding member is made of a material different from that of the housing, for example, the light-shielding member is made of a metal having high thermal conductivity, such as aluminum or copper, and the housing is made of a polycarbonate resin or the like, thereby improving the heat dissipation of the light emitting diode and stabilizing the light emission characteristics. You can also. The housing is preferably provided with a lens that collects light from the light emitting diode. In particular, if the housing of the LED display has a lens that collects the light from the light emitting diode via packing such as urethane foam, the color mixing property can be improved by using light emitting diodes with a wide viewing angle and different emission colors. Can be further improved. When a light emitting diode is used unlike a light bulb, the thickness can be reduced. However, if the position of the light emitting display surface of the light emitting diode and the lens are too far apart, the brightness decreases. On the other hand, if the position of the display surface of the light emitting diode and the lens are too close, the color mixing property is reduced when two or more types of LED chips are used. Therefore, various selections such as the lens focal point and the luminance of the light emitting diode can be selected as desired. The distance between the display surface of the light emitting diode and the lens surface is preferably 60 mm or more and 100 mm or less, depending on the luminance and the like. More preferably, it is 78 mm or more and 95 mm or less.

The housing 402 is exposed to the external environment, so that moisture, dust, and the like do not enter. The housing 402 and the housing, and the opening of an electric cord 403 that establishes electrical continuity between the housing and the light emitting diode. Are preferably sealed with packing. Further, an opening for circulating the air inside the housing in which the light emitting diode is arranged or discharging the air to the outside can be formed.

Since the housing 402 is affected by heat from a light emitting diode or the like, it is preferable that the housing 402 has a small coefficient of thermal expansion in consideration of adhesion to a filler. In addition, it is desirable to use a material that is easy to mold because it is formed into a desired shape. Specifically, various materials such as a polycarbonate resin, an ABS resin, an epoxy resin, and a phenol resin, aluminum, an alloy thereof, and the like are preferable as a material of such a housing.
In particular, aluminum is particularly preferable because heat of the light emitting diode can be released to the outside.

The light-shielding member can be used to prevent the light-emitting diode from being difficult to see due to external light irradiation. Therefore, the length, thickness, and angle of the light blocking member are determined in consideration of the installation location and the set viewing distance.
It is preferable that the angle of the light shielding member can be changed according to the viewing distance. The installation angle of the light shielding member with respect to the housing can be selected as desired depending on the viewing distance, the installation angle of the housing, and the like, but is preferably 0 ° to 10 ° with respect to the vertical direction of the display surface. Further, the light shielding member may be colored black or the like for the purpose of improving the light shielding efficiency.

The light shielding of the LED display varies depending on the installation angle of the LED display, the length and thickness of the light shielding member, the angle of the light shielding member with respect to the housing, and the like. Considering the usage environment, the LED display should be tilted from 0 to 10 degrees with respect to the ground plane and grounded, or the length of the light shielding member should be increased so that sunlight rays of 30 to 45 degrees are not directly irradiated. It is preferable to arrange them to improve the contrast. When the partial change in the amount of light on the display surface is direct sunlight, it can be shielded to some extent by a light shielding member.

When the power supply is AC for driving the light emitting diode group, a power supply for the light emitting diode can be provided by providing a rectifier circuit or the like. Further, when one of the light emitting diode groups or the light emitting diodes connected in parallel within the light emitting diode group cannot be turned on , a control circuit for detecting a power change of the light emitting diode group and detecting an abnormality can be provided. is there. In particular, when one of the circuits connected in parallel is disconnected, a large amount of power flows to the other circuit, so that the luminance is improved. Therefore, it is preferable that the allowable amount of the light emitting diode is set in consideration of the increased current.

[0031]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Specific embodiments of the present invention will be described below, but it goes without saying that the present invention is not limited to these embodiments.

Example 1 A blue-green light-emitting diode (emission wavelength: 495 nm) having a light-emitting layer of an LED chip containing InGaN and InGa
An LED display was constructed using a yellow light emitting diode (590 nm) with AlAs. Two ceramic substrates on which a conductive pattern was formed were adhered, and blue-green and yellow light-emitting diodes were arranged on the substrate on which the three-layer conductive pattern was formed, as shown in FIG. Two light emitting diode groups shown in FIG. 2 are arranged in a spiral. When all the light emitting diodes are arranged, it becomes as shown in FIG. As shown in FIG. 6, the surface of the substrate is formed such that a pattern connected to a lead wire of a light emitting diode on which an LED chip is mounted serves as a heat dissipation surface. The internal circuit of the LED display is a three-parallel circuit for each light emitting diode group. In each circuit, as shown in FIG. 3, a blue-green color is connected in parallel, and a conductive pattern is formed so as to connect a blue-green color and a red color in series. The power cords connected to the external power from the respective light emitting diodes and the board were respectively connected by solder, and then fixed in the railway signal housing shown in FIGS. 4 and 5. The LED display is disposed in an aluminum die-cast housing provided with a light-shielding member, and the surface thereof is sealed with a silicone rubber filler 501. The display surface of the housing 402 is provided with a white lens 401 at a distance of 80 mm from the display surface of the LED display in order to display light from the LED display with better color mixing. Further, the electrical wiring 403 of the LED display was sealed in the housing through rubber packing from the back surface of the housing. The traffic light thus formed was disconnected for each part, and the shape and color mixing of the light emitting display surface were examined.
Note that a control circuit is provided to protect the light emitting diode.

The LED display formed as described above is
It was measured by PKON BM-7. Input power 20.4W
Axial light degree (frequency 60Hz) is 2 8.9 cd,
(X, y) = (0.4952, 0.401) on the chromaticity coordinates
6). Next, one of the spirally arranged light emitting diode groups was intentionally disconnected. In this state, the same measurement was performed for each light emitting diode group.
6.3 cd and 16.6 cd. On the chromaticity coordinates, (x, y) = (0.4918, 0.4200) and (x, y) = (0.4920, 0.4183),
Even if one of the light emitting diodes was turned off, the color mixture was good and the deviation of the chromaticity diagram was extremely small. Similarly, no matter which spiral light emitting diode group was turned off, the light emitting surface was observed in a perfect circular shape. Next, one of the blue-green light emitting diodes intentionally connected in parallel was turned off from a state where all the light emitting diodes were made to emit light. In this state, it was 25.8 cd when similarly measured. On chromaticity coordinates,
(X, y) = (0.4989, 0.4060),
Even if one of the blue-green light emitting diodes connected in parallel was turned off, the color mixing did not significantly deteriorate. It is conceivable that the color mixture collapse was caused by the fact that one blue-green light emitting diode was turned off and the current flowing in the other blue-green light emitting diode was increased but not doubled. Even if any of the spiral light emitting diode groups are turned off or partially turned off, they still fall within the railway signal standards.

Comparative Example 1 The measurement was performed in the same manner as in Example 1 except that the arrangement of the light emitting diode group was changed from a spiral shape to two concentric circular light emitting diodes alternately. As in Example 1, the color mixing when one of the light emitting diode groups was turned off was examined. It was found that the color mixing property was significantly reduced as compared with Example 1. It is considered that the color mixing property is greatly reduced due to the absence of the light-emitting diodes which are concentrically close to each other.

[0035]

According to the first aspect of the present invention, the reliability of the LED display is improved, and even when one of the light emitting diode groups is turned off, the display shape of the LED display device is changed or the color mixture is deteriorated. LE does not drop significantly
It can be a D display. In particular, an LED display having high color mixing can be obtained when mixed color display is performed by combining monochromatic light emitting diodes having different emission wavelengths.

According to the configuration of claim 2 of the present invention, even when one of the light emitting diode groups is turned off, the other light emitting diode group does not greatly deteriorate the color mixing as compared with the case of full lighting. can do.

By adopting the configuration of claim 3 of the present invention, it is possible to prevent color unevenness and obtain an LED display having higher color mixing.

With the configuration of claim 4 of the present invention, the reliability of the LED display is improved, and the display shape of the LED display does not change even when one of the light emitting diode groups is turned off. can do. Further, an LED display having high color mixing can be obtained.

According to the configuration of claim 5 of the present invention, light emitting diodes having different driving voltages can be stably emitted with high luminance.

[Brief description of the drawings]

FIG. 1 is a schematic plan view of a light emitting display unit according to the present invention.

FIG. 2A is a configuration diagram illustrating a first light emitting diode group in FIG. 1, and FIG. 2B is a configuration diagram illustrating a second light emitting diode group in FIG.

FIG. 3 is a schematic diagram showing an example of a circuit diagram of the LED display of the present invention.

FIG. 4 is a schematic diagram showing a railway signal using the LED display of the present invention.

FIG. 5 is a schematic sectional view of the railway traffic signal in FIG.

FIG. 6A is a partial cross-sectional view of a substrate on which a light emitting diode used in the present invention is arranged, and FIG.
(B) shows the plan view.

[Description of Reference Numerals] 101: yellow light emitting diode 102: blue-green light emitting diode 103, 601: substrate 201: yellow light emitting diode of first light emitting diode group 202: Blue-green light-emitting diode of first light-emitting diode group 203: Yellow light-emitting diode of second light-emitting diode group 204 Blue-green light-emitting diode of second light-emitting diode group 401: Condensing lens 402 ... housing 403 ... power supply connection cord 501 ... filler 602 ... conductive pattern of the board on which the mounting leads are arranged 603 ... conductivity of the board on which the mounting leads are arranged Conductive pattern on the substrate on which the inner leads with a smaller surface area than the conductive pattern are placed

Claims (5)

(57) [Claims] 1. A light emitting diode group in which at least two types of light emitting diodes having different emission wavelengths are connected in series on a substrate, and an LED display in which two or more light emitting diode groups are connected in parallel, wherein the light emitting diode group a first light emitting diode groups arranged in a substantially spiral shape, between the first light emitting diode group
LED indicator, which comprises chromatic <br/> a second light emitting diode groups arranged in a substantially spiral shape. 2. The LED display according to claim 1, wherein one of the light-emitting diodes having different emission wavelengths has higher visibility than the other and is arranged symmetrically about the center of the LED display. 3. The LED display according to claim 1, wherein light-emitting diodes having lower luminosity than the light-emitting diodes having different emission wavelengths are arranged along the outermost periphery of the display surface of the LED display. 4. An LED display having a plurality of light emitting diode groups connected in parallel on a substrate, wherein the first light emitting diode group includes at least a spirally arranged light emitting diode group; And a second light emitting diode group spirally arranged between the first light emitting diodes spirally arranged, each of the light emitting diode groups being expressed by color using two or more types of light emitting diodes. An LED display characterized by being made to work. 5. The light-emitting diode group includes a light-emitting diode using a gallium nitride-based semiconductor and a light-emitting diode using indium, gallium, aluminum, and arsenic-based semiconductors connected in series. The LED indicator according to claim 4, wherein the LED indicators are connected in parallel.