Light-emitting display device

Abstract

To provide, at low cost, a light-emitting display device of slim and power-saving type with which it is possible to cause an entire belt-like light-emitting area to statically emit light, cause it to statically emit light in color and brightness gradations, and further cause it to dynamically emit light such that light flows smoothly without breaks, as well as save extra space outside of a display area.SOLUTION: LEDs 2A-2D are arranged at two points on at least one short side of a transparent material 1 having a belt-like light-emitting area 5, and light condensing reflection planes 4A-4D for condensing incident light from an incidence plane and guiding it to direct the travel direction toward a long-side prescribed area are formed near the LED of the transparent material. A sawtooth irregularity 6 for causing light having arrived from each LED to be reflected to change the travel direction to a direction almost perpendicular to the long side is formed on the long side of the transparent material. A reflective exit prism 8 for emitting light reflected from the sawtooth irregularity to the outside is formed with ridgelines in a direction almost perpendicular to the long side, on the rear of the transparent material corresponding to the light-emitting area 5.SELECTED DRAWING: Figure 1

Description

Technical Field

[0004] , , , ,

[0003]

[0001] The present invention relates to a light-emitting display device using LEDs. More specifically, it relates to a light-emitting display device capable of dynamic expression by the light emission of a light guide.

Background Art

[0002] LED display devices in which the light-emitting area changes or moves are used in various applications such as production devices for gaming machines and vending machines, guiding lights, advertising billboards, store displays, vehicle turn signal lamps, indicators for water purifiers, and direction indication displays for autonomous mobile transport vehicles. Generally, the commonly used method is to directly arrange a large number of LEDs in the light-emitting area and sequentially turn them on and off. However, in such a display device, the light emission of each LED appears to shine in a lump.

[0003] In recent years, as artificial intelligence and robot technology have been applied in various fields, the information to be transmitted from machines to humans has been rapidly advanced and diversified, and the importance of the human-machine interface has increased. For example, in an advanced driving assistance system of an automobile, it is necessary to transmit information that allows the driver to appropriately understand the operating state and assistance state of the system. Even for a driver who has taken their eyes off the front instrument panel, light-emitting displays that are intuitive and easy to understand are being provided to the driver from various locations in the interior space such as the ceiling and floor. The information transmitted here varies, such as alarm / attention唤起 / information sharing, depending on the urgency and importance. The important thing is that a display design suitable for the nature of the information is being implemented.

[0004] It should be noted that there is an unclear "唤起" in the original text which may need to be further clarified for a more accurate translation. I translated it as "唤起" for now.A method of displaying information intuitively by placing dynamic light-emitting display devices, which convey information through the color and movement of light, on ceilings and floors is being envisioned. However, when using a display device with a large number of LEDs arranged in a light-emitting area for such applications, the individual LEDs glow excessively brightly, making it unsuitable for displaying information that should be subtly conveyed by being constantly illuminated. Furthermore, while interior design is important for such light-emitting displays, the dotted appearance of the LEDs detracts from creating a calm and relaxing atmosphere, making it undesirable. Against this backdrop, there is a need for a display device that can emit static light with uniform brightness across the entire light-emitting area, while also being able to produce dynamic light that flows smoothly and gently.

[0005] In recent years, there has been an increasing trend towards incorporating display devices that use color changes and light movement to visually communicate the operating status of devices to users in an easily understandable way. In such applications, where soothing visual effects and aesthetic appeal are important, there is a strong demand for display devices that can emit dynamic light that flows smoothly and gently.

[0006] Even in display devices that directly arrange LEDs, it is possible to eliminate the granular appearance of the LEDs by arranging the LEDs at a narrow pitch and placing a diffuser plate in front of them. However, this requires using a very large number of LEDs and controlling the lighting of each one individually, which leads to the problem of complex electronic circuits and wiring, and high device costs.

[0007] To solve these problems, light-emitting devices using light guides have been proposed. For example, Patent Document 1 proposes a light-emitting display device comprising a main light section having a light-emitting area and a secondary light guide section that does not emit light itself but connects to the main light section to guide the light from the LED. This light-emitting display device makes it possible to achieve both static uniform illumination and smooth dynamic illumination with a small number of LEDs. In addition, the use of light guides makes it possible to realize thin display devices. However, this display device has the following drawbacks: ▲1▼ Extra space is required to position the secondary light guide along the strip-shaped light-emitting area, which limits its application. ▲2▼ A structure is required to conceal the secondary light guide for aesthetic reasons, which limits its application. ▲3▼ The cost is high because the fixing and concealing structures of the light guide become complex. ▲4▼ Because a light guide with a complex shape is used, various difficulties arise in mold processing, molding, and handling of the light guide, which is a factor that drives up costs. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2019-129135 [Overview of the project] [Problems that the invention aims to solve]

[0009] In view of the above circumstances, the present invention provides an inexpensive, thin, and power-saving light-emitting display device that can uniformly emit static light across an entire strip-shaped light-emitting area, emit static light with gradients of color and brightness, and emit dynamic light that flows smoothly without interruption, while saving extra space outside the light-emitting area. [Means for solving the problem]

[0010] This invention was made to solve the problem of a strip-shaped light-emitting display device that provides smooth, dynamic light effects. This light-emitting display device consists of a light guide having a band-shaped light-emitting area and LEDs, with two or more LEDs arranged on at least one short side of the light guide, and a focusing reflective surface formed near each LED of the light guide to focus the incident light from the incident surface and guide it toward a predetermined area on the long side, and a sawtooth pattern of irregularities arranged in the predetermined area to change the direction of travel of the light arriving from each LED and reflect it toward a direction approximately perpendicular to the long side, and a reflection-emitting prism arranged on the back of the light guide corresponding to the light-emitting area in a direction approximately parallel to the long side to emit the light reflected from the sawtooth pattern to the outside, and is characterized by being able to change the brightness gradient and the color gradient of the light-emitting area by changing the order of light emission, light intensity and light emission color of the LEDs to perform dynamic display effects. [Best Mode for Carrying Out the Invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 shows a typical configuration of LEDs and a light guide, which are components of the display device of the present invention, and is a view from the front (observer side). Hereinafter, the longitudinal direction of the display surface of the light guide will be the X-axis, the direction perpendicular to the display surface will be the Y-axis, and the thickness direction of the light guide will be the Z-axis (positive direction towards the observer). Four LEDs are arranged on both short sides of the strip-shaped light guide 1, with LED2A and LED2B on the left short side and LED2C and LED2D on the right short side.

[0012] The light guide has a pair of focusing and reflecting surfaces 4A to 4D formed in close proximity to LEDs 2A to D. Sawtooth grooves 6 are arranged along the upper and lower long sides of the light guide. On the back surface of the light guide in the effective area 5 (opposite the observer), reflection and emission prisms 8, which reflect light and emit it outside the light guide, are arranged along ridges approximately parallel to the longitudinal direction. Figure 1 shows the ridges of the reflection and emission prisms as solid lines. The entire surface of the light guide (the side facing the observer) is mirrored.

[0013] Figure 2 shows the optical path before and after the light from LED2A is focused by the focusing reflective surface 4A. The light emitted from LED2A is taken into the light guide from the incident surface 3A. The focusing reflective surface is a pair of curves similar to a parabola in the XY plane, and reflects the light radiating from LED2A so as to align it within a certain angular range in the XY plane, guiding it to a predetermined area 7A on the upper long side. Here, some light is generated that does not reach the predetermined area and does not contribute to the intended illumination display, but the main effective light is guided to the predetermined area.

[0014] Figure 3 shows the optical path before and after the light from LED2B is focused by the focusing reflective surface 4B. The pair of focusing reflective surfaces 4B similarly reflect the light radiating from LED2B, aligning it within a certain angular range in the XY plane, and guiding it to a predetermined area 7B on the lower long side. In Figure 1, the light from LED2C and 2D is guided to predetermined areas 7B and 7C on the upper and lower long sides, respectively, using a similar principle.

[0015] The upper and lower long sides are formed with sawtooth grooves, which reflect the light arriving from the LED so that its direction of travel is changed to a direction approximately perpendicular to the long side. The reflective-emitting prism is formed as a continuous groove or ridge along the edges approximately parallel to the long side. The light that has been reflected by the sawtooth grooves and its direction of travel is reflected by the reflective-emitting prism and emitted in the forward direction. Here, in the light guide path from the focusing reflective surface to the sawtooth grooves, the angle between the direction of the edges of the reflective-emitting prism and the light guide direction in the XY plane is small (almost parallel), so the light that hits the reflective-emitting prism is not emitted in the forward direction. On the other hand, in the light guide path after the direction of propagation has been changed by reflection from the sawtooth irregularities, the direction of the ridge of the reflective-emitting prism and the direction of light guidance are almost perpendicular, so the light that hits the prism surface is reflected and emitted in the forward direction.

[0016] Figure 4 is a cross-sectional view of a reflecting-out prism, where arrows indicate the optical path where light reaching the prism surface is reflected and changes direction towards the front (positive Z-axis direction). The proportion of light emitted changes depending on the height H and pitch P of the reflecting-out prism 8; therefore, the brightness distribution within the light-emitting area can be appropriately controlled by designing it to gradually change the height and pitch. Since the pitch of the reflecting-out prism is directly visible to the observer, it is desirable to keep the pitch at 2 mm or less to avoid being visually distracting at normal viewing distances. Figure 1 shows a coarser pitch than the desirable pitch for visualization.

[0017] Figure 5 illustrates the optical path in which light reaching the sawtooth grooves is reflected and changes direction. There are two types of sawtooth grooves: symmetrical sawtooth grooves 6α that reflect light from both the left and right sides in a direction approximately perpendicular to the edge of the reflecting-out prism, and asymmetrical sawtooth grooves 6β that reflect light from one side in a direction approximately perpendicular to the edge of the reflecting-out prism.

[0018] The 6β reflective surface shape can reflect light entering at a wider angle than the 6α reflective surface shape in a direction approximately perpendicular to the ridge of the reflecting / emitting prism (A). On the other hand, the direction in which light arriving from the right is reflected by the 6β reflective surface shape is significantly deviated from the direction perpendicular to the reflecting / emitting prism, so the light does not become emitted towards the observer (B). Thus, the 6β reflective surface shape has both advantages and disadvantages, but the advantages outweigh the disadvantages in areas close to the LED. To ensure that the light emission area is appropriately set according to the light emission of each LED, a symmetrical sawtooth uneven area and an asymmetrical sawtooth uneven area are separated.

[0019] Figure 6 illustrates the division of areas 6α and 6β. Area 6α is formed in the area where light arriving from both the left and right sides is to be used for display illumination. In the case of 6β, the obtuse angle side is arranged to face outward (towards the LED). Here, it is not necessary for all the arranged sawtooth protrusions to have the same shape; in some cases, slightly changing the angle of the reflective surface depending on the position where it is formed may be preferable to make the display brighter. Also, by making the reflective surface of the sawtooth protrusions a gently curved surface, the angle of propagation after reflection is widened, which leads to an improvement in the viewing angle characteristics.

[0020] Figure 7 illustrates the relationship between the predetermined areas on the upper and lower long sides corresponding to each of the LEDs 2A to D and their brightness distributions. When each of the LEDs 2A to D is illuminated individually, the brightness distribution at the center of the short side is 9A to D. The brightness profiles of each LED overlap with those of adjacent LEDs. When two or more LEDs are lit simultaneously, the brightness distribution is the sum of the brightness distributions when they are lit individually. The fact that the profiles overlap with those of adjacent LEDs is important for creating a visual effect that continuously changes the light-emitting area, and is also important for illuminating the entire area simultaneously with uniform brightness. The brightness distribution when each LED is lit individually can be controlled by the shape of the light-gathering reflective surface and the placement of the LEDs.

[0021] Figure 8 illustrates the principle of changing the luminance distribution when performing dynamic effects. As an example, it shows the case where the current value (=luminous flux) of LED2A is increased first, followed by the current values ​​of LED2B, LED2C, and LED2D being increased sequentially with time differences. The luminance distribution when the current value of LED2A is 50% is denoted as A50, and the luminance distribution when the current value is 100% is denoted as A100. The observed luminance distribution L is the sum of the luminance distributions of each individual LED, so it changes from L1 → L2 → L3 → ... L8. By continuously changing the current value of each LED, a light effect is achieved in which a band of light extends from left to right, becoming stronger as it moves. Furthermore, when all four LEDs are lit simultaneously, the entire display will emit light with a seamless and uniform luminance distribution.

[0022] In the light-emitting display device of the present invention, in addition to the effect display by the above-described luminance change, by using a package in which three RGB chips are combined into one package, it is also possible to perform an effect display that dynamically changes the color gradation. If LED2A is lit blue (B), LED2B and LED2C are lit green (G), and LED2D is lit red (R) simultaneously, the display will change in color gradation from blue - light blue - green - yellow - red.

[0023] By changing the emission color and emission intensity of each LED, dynamic effect displays can be performed in various variations. As an example, first, all of LED2A~D are lit blue, and then, as described above, when the red emission is changed by sequentially and continuously changing the emission intensities of LED2A, 2B, 2C, and 2D, a band-shaped emission with a magenta gradation will smoothly move from left to right on the blue background color.

[0024] The light emission of the display device of the present invention becomes light emission in which the pitches of the sawtooth irregularities are arranged in stripes. Since the angle of these stripes changes with the viewing direction, the light emission has a three-dimensional effect that makes the thin light guide appear to have depth, enhancing the aesthetic value. The pitch of the sawtooth irregularities is important because it affects the three-dimensional effect and texture of the light emission.

[0025] In a general light-emitting display device used indoors, the appearance from a distance of approximately 30 cm to 1 m is important, and a desirable pitch of the sawtooth irregularities for such applications is 0.5 to 5 mm.

[0026] Regarding the behavior of light in the light guide in the present invention, to some extent, there is also light that causes undesirable noise emission without contributing to the intended effect. For the light incident surface, the light collecting and reflecting surface, the sawtooth irregularities, and the outer peripheral end surface that does not correspond to any of these, measures such as black painting or attaching black tape are effective for the purpose of absorbing light and removing noise emission.

[0027] In this invention, the light-emitting area can be formed on the back surface of the light guide with a freely designed pattern. An example is shown in Figure 9. The hatched area is the light-emitting area, which can be a wave-like design as in (A) or a design with letters or symbols arranged as in (B). In these cases, a reflective emission prism can be formed on the back surface within the light-emitting area, forming a ridge line approximately parallel to the longitudinal direction, and the back surface outside the light-emitting area can be made into a mirror surface. Furthermore, in this invention, it is also possible to curve the material in the thickness direction (Z direction), allowing for expansion into various shapes.

[0028] In this invention, the external shape of the light guide is not limited to a rectangle, but can also be a gently curved shape. In this case, the reflected and emitted prism is formed by curving the edge so that it follows the curved longer side.

[0029] Figure 10 shows an example configuration of a light-emitting display device having an arc-shaped light-emitting area. The light from LEDs 2A to 2D is focused by the light-gathering reflective surfaces 4A to 4D. In the previous embodiment, the predetermined areas of LEDs 2A to 2D were set alternately on the upper and lower edges, but in this configuration example, all predetermined areas are set on the upper edge (large diameter side). Sawtooth grooves 6 are formed on the long side of the large diameter side, and the direction of propagation is changed to be approximately perpendicular to the reflective output prism by the sawtooth grooves before being emitted by the reflective output prism.

[0030] In this invention, the number of LEDs is not limited to two on each of the short sides, but can be arranged in groups of three or more. The requirement of this invention is to reflect the light from each LED so that it is aligned within a certain angular range by a focusing reflective surface, and to guide the light to a predetermined area on the long side. There are many variations in which of the upper and lower long sides the predetermined area is located and in what order. The basic principle of this invention holds true if the angle (in the XY plane) between the edge of the reflecting / emitting prism and the direction of light guidance in the light guidance path to the predetermined area is small.

[0031] In the display device of the present invention, mounting multiple LEDs on the same substrate reduces the cost of electronic components and harnesses, which offers a particularly significant advantage.

[0032] Some electronic products, such as the front structure of a household air conditioner's indoor unit, have detachable components. When it is necessary to illuminate such components, attaching electronic components directly to the detachable structure requires routing harnesses using connectors, etc. This complicates the structure, increasing costs, making maintenance cumbersome, and increasing the likelihood of malfunctions. In contrast, according to the present invention, the LED board can be installed on the fixed (non-detachable) component side of the main body, and the light guide can be installed on the detachable component side, resulting in a simple structure and a light-emitting display device that is free from malfunctions and other problems.

[0033] In the light-emitting display device of the present invention, the part directly involved in the display is the light-emitting area of ​​the light guide, and it is preferable to cover parts not involved in the display, such as the LED substrate and the light-collecting reflective surface, with an opaque material to prevent them from being exposed. The first purpose of this is to improve the aesthetic appearance when the display is not emitting light, and the second purpose is to avoid a decrease in display quality, as if the LED substrate part were exposed, light that does not enter the light guide and leaks out would directly enter the viewer's field of view. Furthermore, while the light-emitting display device of the present invention can display light dynamically as is, it is also possible to diffuse the light emitted from the light guide by providing a light-diffusing plate or the like in front of the display area, thereby resulting in a softer light emission and adding a new design aesthetic.

[0034] Furthermore, as shown in Figure 11, the light-emitting display device itself is positioned in a location that is not directly visible, and the light emitted from the light guide illuminates the illuminated surface 10, allowing for indirect observation of the illuminated light.

[0035] As the material for the light guide of the present invention, a highly transparent thermoplastic resin is preferably used, and specifically, examples include polymethyl acrylate, polycarbonate, and polyolefin resins. The light guide can be mass-produced inexpensively by injection molding using a corresponding mold.

[0036] Some of the light that reaches the reflective prism 8 is emitted to the back side rather than towards the observer. By placing a light-reflecting material (diffuse or specular) behind this back side, the light emitted to the back side can be reflected back towards the observer, allowing the reflected light to be used for display as well. Depending on the purpose, such a structure may be used.

[0037] One feature of the display device of the present invention is that, because the light guide is transparent, the back side is visible. Therefore, if the display device of the present invention is placed in front of some structure or in front of another display panel, the structure or other object behind it will be visible when the display device is not emitting light, and the illuminated display of the display device of the present invention will be visible when it is emitting light. Specifically, by placing the display device of the present invention in front of a liquid crystal panel or the like, a layered display can be achieved.

[0038] Furthermore, one or more LEDs can be added to the back of the display device of the present invention, emitting light towards the observer. For example, by controlling the light emission of the LEDs on the back so that it can be seen through the display device of the present invention, it becomes possible to provide a display device that displays in a layered manner with the point-like light of the LEDs and the band-like light of the display device of the present invention. Effects of the Invention

[0039] According to the present invention, the light emitted from each LED is distributed in a gentle, mountain-like pattern with peaks at different positions, and these distributions overlap. Therefore, by continuously changing the light intensity of the LEDs, the light moves smoothly and continuously. This makes it possible to create effects that make the light appear to flow smoothly, and by lighting them simultaneously, it is also possible to achieve static illumination where the entire display emits light uniformly. [Industrial applicability]

[0040] The present invention can be used as a strip-shaped light-emitting display device. In particular, it can be suitably used as an interior illumination for automobiles, illumination for amusement machines, a light-emitting display device for indicating the operating status of electronic devices, a human-machine interface, and the like. [Brief explanation of the drawing]

[0041] [Figure 1] This figure shows the basic configuration of the present invention's light-emitting display device. [Figure 2] This diagram illustrates the behavior of light emitted from LED2A and reflected by a focusing reflective surface. [Figure 3] This diagram illustrates the behavior of light emitted from LED2B and reflected by a focusing reflective surface. [Figure 4] A diagram illustrating the behavior of light reaching the reflected / exited prism. [Figure 5] A diagram illustrating the behavior of light upon reaching the sawtooth-like surface. [Figure 6] Diagram illustrating the formation areas of two types of sawtooth-like grooves. [Figure 7] This figure illustrates the relationship between the configuration of the present invention's light-emitting display device and its brightness distribution characteristics. [Figure 8] A diagram illustrating the principle of continuous change in brightness distribution. [Figure 9] Diagram showing design examples of the light-emitting area. [Figure 10] A diagram showing another example configuration of a light-emitting display device. [Figure 11] A diagram illustrating an example of an applied use of a light-emitting display device. [Explanation of symbols]

[0042] 1. Light guide 2A~2D LED 3A,3B Incidence plane 4A~4D Light-gathering reflective surface 5. Illumination Area 6. Serrated teeth 7A~7D Designated Area 8 Reflection and emission prism 9 Brightness distribution L1~L8 combined luminance distribution 10 Illuminated surface

Claims

1. The device consists of a light guide having a strip-shaped surface and LEDs, with two or more LEDs arranged on at least one short side of the light guide, and a focusing reflective surface formed near each LED of the light guide to focus the incident light from the incident surface and guide it toward a predetermined area on the long side, and in this predetermined area a sawtooth pattern is arranged to change the direction of travel of the light arriving from each LED and reflect it toward a direction approximately perpendicular to the long side, and on the first surface formed along the long side of the light guide, opposite to the observer's side, a reflection-emitting prism is arranged along a ridge approximately parallel to the long side to emit light toward the outside, so as to form an emission area. A light-emitting display device is configured such that the predetermined area is provided on a surface formed along the long side of the light guide, other than the first surface and the second surface on the observer's side facing it, and the shape of each light-collecting reflective surface and the arrangement of each LED are determined such that the luminance distribution of the light-emitting area when each LED is lit individually is arranged at different positions in the direction of the long side, and the luminance distributions of two or more LEDs that are adjacent in the direction of the long side overlap, and by changing the order of light emission, the intensity of light emission, and the color of light emission of the LEDs, dynamic effects can be displayed by changing the luminance gradient and the color gradient of light emission within the light-emitting area.

2. The light-emitting display device according to claim 1, wherein the longer side is formed in a curved shape, and the reflective emission prism is formed by curving the ridge line along the curved longer side.

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