JPH0257313B2 - - Google Patents

Description

[Detailed description of the invention]

[Technical Field of the Invention] The present invention relates to a large color display device for displaying information such as images and characters in color on an electronic display board at a baseball field, or outdoors on the roof or wall of a building. [Technical background of the invention and its problems] In general, this type of large color display device is required to be visible as a color television image from a long distance, for example, 200 meters away.
The display surface is formed into a rectangular shape with one side of 5 m or more. As shown in FIG. 1, a plurality of picture elements 2 each consisting of three or four light sources emitting at least red, green, and blue light are arranged in a matrix on the display surface 1. It is desirable that these picture elements 2 be small and provided as many as possible in order to obtain display screen brightness, color tone when mixed colors, and image resolution comparable to those of a general color television image. For this reason, 1 picture element 2
The desired size is 90mm or less on one side. By the way, for example, if a rectangular picture element 2 with a side of 90 mm is placed on a rectangular display surface of 5.5 m in height and 14 m in width, it will be 60 m in height.
There will be a total of 9,300 pieces, 155 pieces per side and 155 pieces horizontally.
As light sources constituting these picture elements 2, incandescent light bulbs, cathode ray tubes, light emitting diodes, fluorescent lamps, etc. are conceivable, or some of them are already in practical use. However, using these light sources alone has advantages and disadvantages, and is problematic in practice. In other words, those using a fluorescent lamp as a light source, as seen in Japanese Utility Model Publication No. 48-23343,
It is formed in a U-shape. When viewed from the front, the light-emitting part is almost I-shaped, and the effective light-emitting area that can be used as a display surface is small, so the amount of light is small and the power required is low. There are drawbacks that don't diminish as much as you might think. Furthermore, as seen in Japanese Patent Publication No. 51-12239, a unit is also known in which red, green, blue, and white straight tube fluorescent lamps are arranged side by side and housed in a transparent case. However, this device has a complicated structure because it supports multiple fluorescent lamps.
Furthermore, since the socket portion is displayed on the front side, the unit becomes large, making it difficult to construct a picture element with a side of 90 mm or less, and the depth of the unit also becomes large. moreover,
This item requires a transparent case, so
There is a drawback that the brightness of the display surface decreases. Furthermore, when considering a light emitting diode as a light source, red and green can provide a practical amount of light, but a blue light emitting diode cannot provide a practical amount of light, so it cannot form a picture element. Furthermore, devices using cathode ray tubes as light sources are already in practical use. For example, as shown in FIG. 2, one picture element 2 is composed of a set of four cathode ray tubes 3 that emit light of two green G, one red R, and one blue B. There is. However, in this case, the shape of the display part of the cathode ray tube 3 is circular and high voltage is required, so the socket part (not shown) becomes large for electrical insulation reasons, and the cathode ray tubes 3 are placed close to each other. This makes it difficult to install the Therefore, the effective light emitting area occupied by the display section relative to the area occupied by the picture element 2 is small, about 22%, and since the picture element 2 is large, the mounting density on the display surface 1 is also reduced.
Therefore, there is a risk that image resolution will deteriorate and visibility at short distances will also deteriorate. Furthermore, the average luminance (hereinafter referred to as average luminance) when emitting white light is as dark as 900 cd/m ² , and the display luminance contrast decreases during the daytime outdoors, which may result in poor visibility. In addition, for those that use incandescent light bulbs as a light source,
As shown in FIG. 3, one picture element 2 is constructed by arranging three color incandescent light bulbs 4 emitting red R, green G, and blue B in a triangular shape. There is. However, in this case, since the shape of the display part of the incandescent bulb 4 is almost circular and the amount of heat generated is large, it is difficult to arrange the incandescent bulb 4 in close proximity. Therefore, the effective light emitting area occupied by the display section of the incandescent light bulb 4 is small, about 44% of the area occupied by the picture element 2, and the picture element 2 is also relatively large, resulting in a low mounting density on the display surface 1.
Therefore, there is a risk that the image resolution will deteriorate and the visibility at short distances will deteriorate. In addition, the incandescent light bulb 4 consumes a lot of power, and in order to obtain the amount of light required for the picture element 2, the power consumption for one picture element is approximately 61W, and the power consumption for one picture element of the cathode ray tube 3 is approximately 61W.
The disadvantage is that it is about 8 times that of 8W, making it uneconomical. Furthermore, as shown by the dotted line in FIG. 14, the incandescent light bulb 4 has the disadvantage that the blue color is biased toward the green side, so that the display range of blue color is narrowed and the white color also has a reddish tinge. [Object of the Invention] The present invention has been made in view of the above-mentioned drawbacks, and it is an object of the present invention to provide a large-sized color display device that can improve the visibility of display and at the same time solve the problem of colors that can be displayed by picture elements. [Summary of the Invention] In order to improve the visibility of the display on a large color display device, it is sufficient to increase the average brightness of picture elements so that the brightness contrast with the surroundings becomes large. For this reason, it is possible to use a light source with high brightness, or to increase the effective light emitting area if the brightness is the same. Therefore, in the present invention, light emitting diodes, which can be closely arranged without heat generation or obstacles such as sockets, are used as red and green light sources to improve the effective light emitting area ratio and reduce power consumption. In addition, high brightness can be obtained by using a fluorescent lamp, an incandescent lamp, or a back-illuminated liquid crystal display as a blue light source whose luminous intensity is significantly reduced when a light emitting diode is used. [Embodiment of the Invention] Next, an embodiment of the present invention will be described based on FIGS. 4 to 7. FIG. 4 shows a large number of picture elements 2 arranged side by side as one unit of display constituting the display surface 1 of the large color display device shown in FIG. In this figure, a portion 11 emits red light, which is located on one side above the center of the picture element 2, and is formed by 20 light emitting diodes 12 that emit red light. As shown in FIGS. 6 and 7, this light emitting diode 12 has a Fresnel lens 13 formed on the head of the cover part, and these lenses are placed close to each other on the side.
They are arranged in parallel on one printed wiring board 14 by soldering or the like. Note that the protective resistor 15 and the like necessary for causing the light emitting diode 12 to emit light are provided on the printed wiring board 1 which is arranged in parallel at the back of the board 14 when viewed from the display surface 1 side of the display device.
It is attached to 6. Reference numeral 17 denotes a part that emits green light, two of which are arranged diagonally of picture element 2, and each part 56 emits green light.
It is formed by individual light emitting diodes 18. These light-emitting diodes 18, like the light-emitting diodes 12 that emit red light, have a Fresnel lens on the head of the light-emitting part, and when the sides are in contact with each other, 1
They are arranged in parallel on two printed wiring boards 14.
The area of the portion 17 that emits green light is approximately 5.5 times the area of the portion 12 that emits red light. Reference numeral 19 denotes a portion that emits blue light, and is formed by a fluorescent lamp 20 that emits blue light. As shown in FIG. 5, this fluorescent lamp 20 has an arc tube display section 21 bent into a substantially U-shape to form a rectangular shape.
The base portion 22 is bent at a substantially right angle toward the inside of the picture element 2 and connected to a socket (not shown), and is disposed on the other side below the center of the picture element 2. Next, the operation of this embodiment will be explained. The main wavelength of the light emitting diode 12 that emits red light is 660 nm, as shown in FIG. 14, and therefore exhibits a clear red color with higher brightness than a light bulb or cathode ray tube. Further, the light emitting diode 18 that emits green light can emit light in substantially the same color as a light bulb or a cathode ray tube. Also, since the light emitting diodes 12 and 18 are small, the luminous intensity of each is 0.2 cd for red and 0.2 cd for green.
Although the brightness is low at 0.12 cd, the brightness is 7000 cd/m ² for red, which is higher than that of a light bulb, and the brightness of green is 5000 cd/m ² , which is equivalent to that of a light bulb. Since the light emitting diodes 12 and 18 have almost no problem with heat generation and operate at low voltage, they do not require a socket and can be easily connected to each other by directly soldering them onto the printed wiring board 14. Can be placed next to each other. Furthermore, since the shape itself is small,
It can be matched to the surface shape of the picture element 2, and can also be placed in gaps between other light sources. Therefore, the effective light emitting area relative to the area occupied by one picture element 2 can be increased, and the average brightness of the picture element 2 can be increased. In addition, since the power consumption of the light emitting diodes 12 and 18 is small, the mounting area and power consumption when the light emitting diodes 12 and 18 are placed adjacent to ^each other as shown in FIG. , the green part 15 is 2800 mm ² and the output is 10 W. In this way, power consumption can be much lower than that of light bulbs, improving economic efficiency. Also, the influence of temperature changes is small. In addition, a fluorescent lamp 20 that emits blue light
Unlike light bulbs, the emitted light color is not biased toward green, and the color gamut is thus widened. Furthermore, as shown in FIG. 5, in the fluorescent lamp 20, the arc tube display section 21 can be modified to match the shape of the picture element 2, and does not require high voltage. There is no need for a particularly large socket, and the effective light emitting area can be widened relative to the area occupied by one picture element 2. Also, the brightness
At 2400cd/m ² , it has twice the brightness of a cathode ray tube. In this way, the effective light emitting area of both the light emitting diodes 12 and 18 and the fluorescent lamp 20 can be increased relative to the area occupied by one pixel 2, so overall, when arranged as shown in FIG. If the area occupied by 2 is 6400 mm ² (80 mm x 80 mm), the effective light emitting area is 4500 mm ² , or 70%, and the effective light emitting area can be much improved compared to the conventional one. For this reason, picture element 2
The average brightness is 3200cd/ ^m2 , approximately 1.8 times that of incandescent bulbs only, and approximately 3.6 times that of cathode ray tubes only.
It can be twice as bright. Furthermore, in a large color display device, the red, green, and blue light sources that make up the picture element 2 are mixed in an observation state where they are sufficiently fused, and the colors can be visually recognized as a color display. Both the light-emitting diodes 12 and 18 and the fluorescent lamp 20 can be arranged in a narrow space to suit the space, so the area occupied by the picture element 2 is reduced to 6400 mm ² (80 mm x 80 mm), compared to the conventional one, without reducing the effective light emitting area. 8100mm ² (90mm×
90mm).
Conventionally, a color television image could only be viewed from a distance of 50 meters or more, but in this embodiment, it can be viewed as a color television image even from a distance of approximately 30 meters. In addition, each data of the conventional example and this example is shown in Table 1 and Table 2.

【table】

[Table] In the above embodiment, the portion 19 that emits blue light was formed by the fluorescent lamp 20 that emits blue light, but this is based on Table 3 showing the brightness and power of the light source that emits blue light. As you can see, the brightness
Although it is bright at 2400cd/ ^m2 , the power consumption is small at 4W, and the arc tube display section 21 is
This is because it has the advantage of being able to be molded to suit, but is not limited to, Figure 10,
Same as fluorescent lamp 20 as shown in FIG.
It may be formed using an incandescent light bulb 23 having a brightness of 2400 cd/m ² or a liquid crystal display 24 with backlighting. As shown in FIG. 11, this incandescent light bulb 23 consists of a bulb 25 and a base 26, and the tip of the bulb 25 is provided with a colored portion 27 colored blue. This incandescent light bulb 23 is screwed into a socket 29 provided with a protective gasket 28. As shown in FIG. 13, the backlit liquid crystal display 24 includes a rectangular plate-shaped liquid crystal 30, polarizing plates 31 and 32 located on the front and rear surfaces of the liquid crystal 30, and polarizing plates 31 and 32 located on the rear surface of the polarizing plate 32. a light source 34 consisting of an incandescent light bulb located at the rear center of the diffuser plate 33;
0, it is formed of a reflecting plate 35 that supports and fixes the polarizing plates 31, 32 and the diffuser plate 33. Note that the diffusion plate 33 is coated with a blue filter.

〔Effect of the invention〕

According to the present invention, since a light emitting diode is used as a light source that emits red and green light, the colors are clear, the color corresponds well to the shape of the pixel, and it is effective for the area occupied by one pixel. The light emitting area can be increased, and therefore the average brightness of the picture elements can be improved, and visibility can be improved. Furthermore, it is possible to reduce the size of picture elements without reducing the effective light emitting area, and as a result, it is possible to arrange a large number of picture elements at high density in one display device, making it possible to finely display the display and to The visibility of the color display can be improved. Furthermore, power consumption can be reduced and economical efficiency can be improved.

[Brief explanation of the drawing]

FIG. 1 is a front view schematically showing a large color display device, FIGS. 2 and 3 are front views showing conventional picture elements, and FIG. 4 is a front view of a picture element of the large color display device of the present invention. FIG. 5 is a front view showing one embodiment, FIG. 5 is a perspective view showing a fluorescent lamp, FIGS. 6 and 8 are front views showing a light emitting diode, and FIGS. 7 and 9 respectively.
10 and 12 are front views of picture elements showing other embodiments of the present invention, and FIG. 11 is a side view showing an incandescent light bulb. FIG. 13 is a sectional view showing a back-illuminated liquid crystal display, and FIG. 14 is a chromaticity diagram. 1... Display surface of a large color display device, 2... Picture element, 12, 12a... Light emitting diode that emits red light, 18... Light emitting diode that emits green light, 20... Blue light emission 21...A luminous tube display section; 23...An incandescent lamp that emits blue light; 24...A backlit liquid crystal display that emits blue light.

Claims (1)

[Scope of Claims] 1. In a large color display device that displays information by arranging a large number of picture elements having light sources of red, green, and blue light emitting colors, the picture elements are light emitting lights that emit light of red and green colors, respectively. 1. A large color display device comprising a diode and at least one light source of a fluorescent lamp, an incandescent lamp, and a backlit liquid crystal display that emit blue light. 2. The large color display device according to claim 1, characterized in that a fluorescent lamp that emits blue light is used as the light source for blue light. 3. The large color display device according to claim 1, characterized in that an incandescent light bulb that emits blue light is used as the light source for blue light. 4. A large-sized color display device according to claim 1, characterized in that a backlit liquid crystal display that emits blue light is used as a light source for blue light. 5. The large color display device according to claim 1 or 2, wherein the fluorescent lamp that emits blue light has an arc tube display section formed in a substantially rectangular shape. 6. The large color display device according to any one of claims 1 to 5, wherein the light emitting diode is constituted by an aggregate of a plurality of light emitting diodes.