JP2005003734A - Luminescent display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a small and thin type luminescent display device of low power consumption, with which simple letters and figures can be displayed by making the letters and figures directly emit light. <P>SOLUTION: Recessed and projection parts 2a matched with the figure of a desired display image 1 are formed on the back of a light guide plate 2, and light emitting elements 3 are arranged on the side faces of the light guide plate 2 so that the light can be guided into the light guide plate 2. Then, the shape of the recessed and projection parts is displayed by irregularly reflecting the the light guided from the side faces. Two or more sets of the light guide plates with these light emitting elements can be used as the structure. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a light-emitting display device capable of displaying a certain image with lightning, such as a guidance display in a public building or a simple advertisement. More particularly, the present invention relates to a light-emitting display device that has a very simple configuration and is easy to appeal using composite colors.
[0002]
[Prior art]
Unlike LED dot matrix display devices and liquid crystal display devices, the display image is not changed at any time, and as a device that displays certain images and characters, such as advertisements and guidance display boards at stations, etc., electric signboards etc. Are known. For example, as shown in FIG. 4, these electric signs are provided with a light source such as a fluorescent tube 51 as a backlight in a reflection case 52, and an image is displayed on the surface of the backlight via a light diffusion plate 53. By installing the drawn display panel 54, the display panel image is lit up. In such a configuration using a fluorescent tube as a backlight, unless the distance between the fluorescent tube 51 and the display panel 54 is increased, the vicinity of the fluorescent tube 51 becomes too bright and becomes dark when separated, so that the image of the fluorescent tube becomes dark. Since it appears and a uniform display image cannot be obtained, there is a problem that the depth becomes thick and the apparatus becomes large (see, for example, Patent Document 1).
[0003]
In order to solve such a problem, as shown in FIG. 5 and used in a liquid crystal display device or the like, a linear shape in which one or a plurality of fluorescent tubes or light emitting diodes (LEDs) are arranged from the side of the light guide plate 61 is used. An image is drawn on the upper surface side by using a planar light source that introduces light from the light source 62 or a point light source and emits light uniformly from the surface side through a light diffusing plate 63 or the like provided on the surface of the light source. There is also known a configuration in which the display panel 64 or the liquid crystal panel is arranged to display an image of the display panel or the liquid crystal panel (for example, see Patent Document 1). In this case, a light reflection film is provided on the back surface or side surface of the light guide plate, or a reflective film pattern of a different size is provided on the back surface of the light guide plate in order to make the luminance uniform on the surface. There is also.
[0004]
[Patent Document 1]
JP-A-8-153405 (FIGS. 17 and 18)
[0005]
[Problems to be solved by the invention]
As described above, when a display image that does not change is displayed by lighting up, the display panel on which the image is drawn is irradiated directly from the light source from the back surface, or by the backlight that is made a uniform planar light source by the light guide plate. By doing so, it is possible to illuminate a beautiful display image and display it with a good appearance. However, in the case of direct irradiation, since the distance between the light source and the display panel has to be increased, the size is increased, and the method using the light guide plate has a problem that the cost is increased. Furthermore, in any of these methods, the display panel is lit up instead of being directly displayed by the light from the light source, so the use of the light from the light source is indirect and wasteful and consumes a lot of power. There is a problem of increased costs.
[0006]
On the other hand, for example, in the case of a simple information display such as an “emergency exit” in a building, an “entrance” or “exit” in a public building, or a billboard with a simple display, the power consumption is low and the price is low. In addition, it is desired that the display be formed thin and draw as much eye-catching as possible.
[0007]
The present invention has been made in view of such a situation, and provides a small and thin light-emitting display device that displays simple characters and figures by directly emitting light, has low power consumption, and is small. Objective.
[0008]
[Means for Solving the Problems]
The present inventor makes irregularities such as hairline processing and embossing on the back surface of the light guide plate and introduces light into the light guide plate from the side surface of the light guide plate with LEDs or the like. It has been found that only the portion where is formed appears to emit light. When light from another display or the like is emitted in a direction perpendicular to the light guide plate, the light is transmitted through the light guide plate as it is, so that the display under the light guide plate and the unevenness of the light guide plate are formed. When two or more light guide plates with irregularities are stacked and light is incident from the side surfaces of the respective light guide plates, the images of the light guide plates are superimposed. It was found that it can be displayed. When two or more light guide plates are overlapped, each light emitting element is shielded so that light of each light emitting element does not crosstalk between the light guide plates, and a gap is provided between the light guide plates. Need to form.
[0009]
The light-emitting display device according to the present invention includes a light guide plate having a concave and convex portion formed on a back surface in accordance with a desired display image, and a light-emitting element provided on a side surface of the light guide plate so that light can be introduced into the light guide plate. It is made up of.
[0010]
Here, the display image means an image made up of numbers, letters, characters, figures and the like, which can be used for signs such as guidance and advertisement. Further, the unevenness means a state where a linear groove (hairline) or embossing is applied.
[0011]
With this structure, it is possible to reflect the light introduced into the light guide plate as it is without creating a display panel or the like on which the display image is drawn in color or the like, thereby obtaining a display image. That is, on the back surface of the light guide plate, irregularities are formed in the portion matching the shape of the display image, and the light introduced into the light guide plate is irregularly reflected by the uneven portions and emitted to the surface of the light guide plate. It appears that light is emitted from the uneven part. That is, it is observed that the light introduced into the light guide plate emits light directly at the portion where the uneven portion is formed. Therefore, unlike indirect lighting using light introduced into the light guide plate, the light introduced into the light guide plate can be used effectively, and a bright display can be achieved with less input. .
[0012]
A plurality of light guide plates provided with the light emitting elements are provided to be overlapped at a predetermined interval, and a display image figure formed on at least two light guide plates is displayed in a superimposed manner, thereby enabling a simple configuration. 3D display can be performed, and for example, a different light guide plate can be used to make the background blurred, so that a light-emitting display device overflowing with freshness can be obtained. Note that “with a certain interval” means that adjacent light guide plates are spaced so that light from the light emitting elements between them is not mixed to the extent that there is no hindrance. Therefore, as long as the two display images can be overlaid without causing the mutual display images to be dispersed, the images may be largely separated.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
Next, the light-emitting display device of the present invention will be described with reference to the drawings. The light-emitting display device according to the present invention has an uneven portion 2a on the back surface that matches the figure of the desired display image 1, as shown in FIG. A light emitting element 3 is provided on the side surface of the light guide plate 2 so as to be formed on the light guide plate 2 and to introduce light into the light guide plate 2.
[0014]
In the example shown in FIG. 1, the display image 1 is an example of an abbreviation of a company name used for company guidance or advertising. However, the display image 1 is not limited to this example. For example, the display image 1 is an emergency exit for guidance in a building. The present invention can be applied to relatively simple images such as guide lights, display lights at entrances and exits in public buildings, graphics for advertisements, advertisements, and the like when images are displayed constantly.
[0015]
The light guide plate 2 can be the same as that used as a normal backlight, and appropriately reflects the light of the light emitting element incident from the side surface to extract the light in a predetermined direction. That is, it is made of, for example, polycarbonate, acrylic resin (PMMA) or the like, is formed to a thickness of about 0.8 to 25 mm, and the uneven portion 2a is formed on the back surface (the surface opposite to the display surface) of the region where light emission is desired. The region desired to emit light is a portion corresponding to the display image 1 described above. For example, as shown in FIGS. 1B and 1C, when the display image 1 is “ROHM”, An uneven portion 2 a is formed on the back surface of the light guide plate 2.
[0016]
In the example shown in FIG. 1, the portion where the uneven portion 2 a is formed is formed in the recessed portion 2 b that is recessed from the back surface of the light guide plate 2, but the portion of the uneven portion 2 a is clarified and diffusely reflected. In order to make it easy to make it, the concave portion 2b is formed, there is no concave portion 2b, and even if the concave and convex portion 2a is directly formed on the back surface of the light guide plate 2, it hardly changes.
[0017]
The irregularities reflect light irregularly, and may be grooves (hairlines) formed in parallel straight lines, or may be wrinkles in which irregularities are randomly formed such as wrinkles. While the light incident from the side face is totally reflected in the light guide plate 2, the light is diffusely reflected by the concavo-convex portion 2 a on the back surface and emitted from the front surface side. That is, as shown in FIG. 2, the path of the light that has entered the light guide plate 2, the light that has entered the light guide plate 2 travels while repeating total reflection in the light guide plate 2, and travels toward the uneven portion 2 a. The incident angle of the light at the concavo-convex portion 2 a changes, and part of the light faces the upper surface of the light guide plate 2 and is emitted from the light guide plate 2. The light that cannot be emitted is reflected again by the other uneven portion 2a while being totally reflected in the light guide plate 2 again, and is emitted to the surface side, and the light that is reflected by the uneven portion 2a and emitted to the surface side is observed. The part 2a appears to shine.
[0018]
That is, in a backlight used for a normal liquid crystal display device, an electric signboard, and the like, in order to extract uniform light from the front surface side, a reflection pattern whose reflection amount is adjusted according to the light intensity is formed on the back surface. In some cases, the light guide plate 2 according to the present invention has a configuration in which light is not reflected by reflection on the back surface of the light guide plate 2 but is formed on the back surface thereof. On the other hand, light incident from the back side of the light guide plate 2 can pass through the light guide plate 2 as it is. Therefore, as will be described later, by overlapping two or more light guide plates at regular intervals, an image displayed by a plurality of light guide plates can be superimposed.
[0019]
The depth of the unevenness depends on the amount of light incident from the light emitting element 3 and the size of the light guide plate 2, but the height at which the light sufficiently repeats total reflection in the light guide plate 2 and is reflected on the upper surface side by the uneven portion 2a. If it is. In the example of the hairline shown in FIG. 1, grooves having a depth of about 0.015 mm are formed at intervals of about 0.02 mm with a light guide plate 2 of 22 mm (length) × 80 mm (width) × 2 mm (thickness). .
[0020]
The light emitting element 3 may be, for example, an LED chip as it is, or a lamp type covered with a dome-shaped resin, or a chip type light emitting element in which an LED chip is mounted on a chip-like insulating substrate and covered with a resin. Further, instead of the LED, it may be incident from another light source through an optical fiber, and a light source such as a fluorescent tube or a cold cathode tube can be used for a large display device. In the present invention, since the light of the light emitting element is directly used as a display image, the use efficiency thereof is high, and the brightness can be sufficiently obtained by the LED if the display is about the normal guide light.
[0021]
The light emitting element 3 is preferably provided with light emitting elements of three primary colors of red (R), green (G), and blue (B) because the display color can be displayed almost in full color. In the case of an LED, the red light emitting element can be manufactured using an InGaAlP compound semiconductor. For a green light emitting element, a GaN compound semiconductor or a GaP compound semiconductor is used, and in the case of a blue light emitting element, a GaN compound semiconductor is used. It is possible to obtain light emission with high brightness with a very small chip of about 0.22 to 0.26 mm × 0.22 to 0.26 mm, respectively. As shown in FIG. 1, by providing the light plate 2 with one color on each of the left and right sides, it was possible to sufficiently display an image on the uneven portion 2 a formed on the light guide plate 2. When the light guide plate is large, bright display can be achieved by providing a large number of light emitting elements.
[0022]
As shown in FIG. 1, the light emitting elements 3 (R), 3 (G), and 3 (B) of the respective colors are arranged so as to be left and right so that light is uniformly distributed in the light guide plate 2. It is preferable because it is easy to diffuse. That is, if light is incident from the center of one side surface of the light guide plate 2, it is relatively easy to diffuse, but if it is incident from the end, the diffusion of light toward the opposite end is sufficient. Therefore, the light emitting elements of the same color that face each other are arranged on the opposite other end side, so that light of any color is easily diffused throughout the light guide plate 2.
[0023]
Further, by forming a drive circuit so that each of the R, G, and B light emitting elements 3 can be turned on and off independently, only the light emitting elements of a desired color are turned on to control the color of the display image. It is possible to mix two or three colors to emit intermediate colors, and change the drive current of each light emitting element and adjust the brightness to mix the colors so that it is almost full color. The desired color can be used to display an image. By using an LED as the light emitting element, such a background color can be easily controlled.
[0024]
As shown in FIG. 1A, the light emitting element 3 may be provided slightly apart from the side surface of the light guide plate 2, or may be directly attached to the light guide plate 2 or may have a recess in a part of the side wall of the light guide plate. It may be formed so that a light emitting element is put therein. Depending on the directivity characteristics of the light emitting element 3, the light emitting element 3 is attached so as to be easily incident and diffused into the light guide plate 2. Although not shown, the periphery of the light emitting element 3 is covered with a reflective film so that light that does not enter the light guide plate 2 does not leak to the display surface side, and almost all of the light emitted by the light emitting element 3 is covered. It is desirable that the light is incident on the light guide plate 2. Furthermore, the side wall on which the light emitting element 3 is provided is not limited to the opposite side wall of the light guide plate, but may be provided on the entire side wall, or may be provided on only one side wall. It is determined according to the required amount of light emission.
[0025]
Further, although not shown, when the light emission in the light guide plate is not uniform, the light from the light guide plate can be uniformly emitted by providing a light diffusion plate made of polycarbonate or the like on the surface side. .
[0026]
According to the light emitting display device of the present invention, it is only necessary to form a concavo-convex portion that matches the shape of the image to be displayed on the back surface of the light guide plate and attach the light emitting element so that light can enter from the side wall of the light guide plate. Simple figures and characters can be emitted with a desired emission color and displayed. That is, the light incident from the side wall of the light guide plate travels in the light guide plate while being totally reflected inside the light guide plate because of the large refractive index difference between the light guide plate and the surrounding air, but is formed on the back side of the light guide plate. Since the light reaching the uneven portion is irregularly reflected by the uneven portion, it is not regularly reflected but irregularly reflected on the surface side. Therefore, it is observed that only the portion where the uneven portion is formed emits light, and is displayed as an image of the shape where the uneven portion is formed. By providing the light emitting elements of the three primary colors R, G, and B as described above, light can be emitted in a desired color.
[0027]
As a result, the utilization efficiency of light to be introduced is very good, a bright image can be displayed even with a small amount of light, and if a single color display is sufficient as a light emitting element, only one ordinary LED is provided on each side. For example, an emergency exit guide light in a building can be displayed with sufficient attention, and power saving can be achieved. In addition, a display panel, a light source, a housing for holding them, and the like are not required, and the light guide plate only needs to be thick, so that it can be installed in a very thin state and attached to a wall or the like.
[0028]
In the above-described example, the light guide plate is composed of only one light guide plate and a light emitting element that makes light incident on the light guide plate. Since it is transmitted, for example, as shown in FIG. 3, two or more sheets can be stacked to form a composite image. In other words, the first light guide plate 2 is formed with a concavo-convex portion corresponding to the image similar to the image shown in FIG. 1 described above, and the second light guide plate 21 has a frame-like image 11 provided only around the periphery. A concavo-convex portion corresponding to is formed. Then, the color of the light emitting element 3 incident on the first light guide plate 2 and the color of the light of the light emitting element 3 incident on the second light guide plate 21 are changed, and the light emitting element incident on the second light guide plate 21 is changed. By reducing the amount of light and blurring it, it can be displayed as an image in which a pattern with a different emission color is superimposed.
[0029]
The images provided on the plurality of light guide plates do not need to be provided in a place where the images do not overlap, and for example, light guide plates corresponding to images that overlap with the figure of Mt. Fuji can be superimposed. Even when images overlap on the upper and lower light guide plates, as described above, the light emitted from the lower light guide plate is observed through the upper light guide plate as it is, and the upper light guide plate is based on the same theory as described above. Since light is emitted in a shape that matches the image formed on the light guide plate, although there is a color mixture of the upper and lower colors, an image in which both are superimposed can be displayed. Similarly, a display device can be configured by stacking three or more light guide plates.
[0030]
In addition, when different designs are formed on the light guide plate and displayed in a superimposed manner, it is necessary to turn on the light emitting elements provided on two or more light guide plates, so that the light of each light emitting element does not mix. In addition, it is necessary to coat with a reflective film so as to prevent light leakage from each light emitting element, and to separate the light guide plates so that light does not travel between the light guide plates. Usually, by providing a gap between the light guide plates, since the refractive index of air is small, it is easy to totally reflect, and it is easy to reflect to the upper surface side by unevenness, so that color mixing can be prevented.
[0031]
【The invention's effect】
According to the present invention, simple display images for advertisements and simple displays such as emergency exits, entrances and exits in buildings can be configured with a very inexpensive device, and light can be used very effectively. Therefore, a light-emitting element can be formed using a semiconductor element such as an LED, and a light-emitting display device that is extremely power-saving and inexpensive can be obtained. In addition, the display color can be changed by periodically changing the emission color, and an accented display device can be obtained.
[Brief description of the drawings]
FIG. 1 is an explanatory view showing an embodiment of a light emitting display device according to the present invention.
FIG. 2 is an explanatory diagram of a principle of emitting light by an uneven portion provided on a light guide plate of a light emitting display device according to the present invention.
FIG. 3 is an explanatory view showing another embodiment of a light emitting display device according to the present invention.
FIG. 4 is an explanatory view showing an example of a conventional electric signboard.
FIG. 5 is an explanatory diagram of a configuration of a backlight used in a conventional electric signboard or liquid crystal display device.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Display image 2 Light guide plate 2a Uneven part 3 Light emitting element

Claims (2)

A light-emitting display device comprising: a light guide plate having a concave and convex portion matching a figure of a desired display image formed on the back surface; and a light emitting element provided on a side surface of the light guide plate so that light can be introduced into the light guide plate. The light emitting display according to claim 1, wherein a plurality of light guide plates provided with the light emitting elements are provided so as to overlap each other at a predetermined interval, and a figure of a display image formed on at least two light guide plates is displayed in an overlapping manner. apparatus.

Images