JP2004200177A - Light source using light emitting diode - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a light source using light emitting diodes, which is the comparatively inexpensive surface light source, and in which the brightness of respective regions of a light guiding plate can be changed, and furthermore, in which the light emitting color of the light guide plate can be changed. <P>SOLUTION: The light guide plate 7 is a plate-formed body, and the light introduced from the peripheral face leaks from at least one face of the front and rear faces. A plurality of light emitting diode elements 1r, 1g, 1b are arranged opposing to one peripheral face of the light guide plate 7, and has three light emitting colors. Because the surface light source in which the light guide plate 7 and the light emitting diode elements 1r, 1g, 1b are combined is obtained by this constitution, the surface light source can be provided at a comparatively lower price. Furthermore, by means of the arrangement of the light emitting diode elements 1r, 1g, 1b and the lighting control, the brightness of the respective regions of the light guide plate 7 can be changed, and the light emitting color of the light guide plate 7 can be changed according to the light emitting color and the arrangement of the light emitting diode elements 1r, 1g, 1b. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a light source using a light emitting diode suitable for lighting and display.

Conventionally, a light guide plate, a long substrate arranged opposite to the side surface of the light guide plate, and a plurality of light emitting devices arranged in a longitudinal direction on the substrate so as to face the side surface of the light guide plate A surface lighting device provided with a diode is provided (for example, see Patent Document 1).
JP-A-6-281929

  The technique described in Patent Literature 1 discloses that the size of a reflecting surface determined by the size of a flat surface and the size of the radius of curvature of the rounded tip of a cross-sectional shape of a convex portion formed on the back surface of a light guide plate is applied to a light emitting diode. The greater the distance, the more uniform illumination can be obtained. However, the emission color is not particularly described.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a relatively inexpensive surface light source that can change the brightness of each region of the light guide plate and also emits light from the light guide plate. It is an object of the present invention to provide a light source using a light emitting diode that can change the light source.

  The invention according to claim 1 is a light guide plate that leaks light introduced from the peripheral surface of the plate-like body from at least one of the front and back surfaces, and a plurality of light colors arranged in a plurality facing the peripheral surface of the light guide plate. A light-emitting diode element.

  According to this configuration, a relatively inexpensive surface light source can be provided by a combination of the light guide plate and the light emitting diode element, and the brightness of each region of the light guide plate changes by the arrangement of the light emitting diode element and lighting control. Can be added, and the emission color of the light guide plate can be changed according to the emission color and arrangement of the light emitting diode elements.

  According to a second aspect of the present invention, in the first aspect of the present invention, the light guide plate is used for an illuminating device provided with a display pattern on at least one of the front and back surfaces of the light guide plate. Light emitting diode elements are arranged so as to increase the number.

  According to this configuration, since the amount of leakage light from the light guide plate is increased in a portion of the display pattern where the amount of transmitted light is large, the contrast between the bright and dark portions of the display pattern is emphasized so that the display pattern can be recognized. It will be easier.

According to a third aspect of the present invention, in the first aspect of the present invention, the light guide plate is used for an illuminating device provided with a display pattern on at least one of the front and rear surfaces of the light guide plate. Are arranged in such a manner that light emitting diode elements of a plurality of emission colors are arranged so as to match with each other.
According to this configuration, the color contrast can be emphasized in the colored display pattern, so that the display pattern can be easily recognized.

  According to a fourth aspect of the present invention, in the first aspect of the invention, the light output of each of the light emitting diode elements is dimmed by dimming means.

  According to this configuration, the light intensity of the light guide plate can be adjusted by dimming the light emitting diode element.

  According to a fifth aspect of the present invention, in the first aspect of the present invention, each light emitting diode element is connected to each group such that the plurality of light emitting diode elements form a plurality of groups, and the lighting state of each light emitting diode element is set to each group. It is characterized by being controllable.

  According to this configuration, it is possible to change the light distribution by performing lighting or dimming for each group.

  According to the configuration of the present invention, a relatively inexpensive surface light source can be provided by the combination of the light guide plate and the light emitting diode element, and the brightness of each region of the light guide plate is controlled by the arrangement and lighting control of the light emitting diode element. And it is possible to change the light emission color of the light guide plate according to the light emission color and arrangement of the light emitting diode elements.

(Embodiment 1)
This embodiment is mainly used for display. As shown in FIG. 1, a plurality of light emitting diode elements 1r, 1g, 1b are arranged so as to face an end face of a flat light guide plate 7. is there. Red, green, and blue light emitting diode elements 1r, 1g, and 1b are used. By using the light emitting diode elements 1r, 1g, and 1b having different emission colors, the mixed color light becomes almost white. The light guide plate 7 is a transparent plate, and is formed so as to guide light while reflecting a part of the light introduced from the end face, and to leak the remaining light from at least one of the front and back surfaces. Therefore, a diffusion plate having a diffuse transmission property is provided on a surface of the light guide plate 7 that leaks light to assist light leakage, and a reflection plate is provided on a surface that does not leak light. The reflecting plate is a small reflecting plate having a small area having diffuse reflectivity and a mirror surface superimposed on the back surface side. The small reflecting plate has an area such that the amount of leaked light becomes almost uniform regardless of the position of the light guide plate 7. And placement is taken into account. In short, in the vicinity of the light emitting diode elements 1r, 1g, 1b, the area of the small reflector per unit area is reduced, and as the distance from the light emitting diode elements 1r, 1g, 1b increases, the area of the small reflector per unit area increases. Make it bigger.

  In the example shown in FIG. 1, the light emitting diode elements 1r, 1g, and 1b are arranged in a line on the end face of the light guide plate 7, but if a larger number of light emitting diode elements 1r, 1g, and 1b are arranged as shown in FIG. Light can be emitted with high luminance. Further, as shown in FIG. 3, by arranging the light emitting diode elements 1 (1r, 1g, 1b) on all the end faces of the light guide plate 7, it is possible to increase the luminance and the uniformity of the luminance.

  The light emitting diode elements 1r, 1g, 1b in the present embodiment are connected in series as a group for each light emitting color, and as shown in FIG. 4, a switching transistor Qr is provided for each series circuit of the light emitting diode elements 1r, 1g, 1b for each color. , Qg. It is connected in series between the collector and the emitter of Qb. Switching transistors Qr, Qg. Qb is individually controlled by the control circuit 2. Therefore, the switching transistors Qr, Qg. The luminance of each light emitting diode element 1r, 1g, 1b can be adjusted by changing the on / off duty of Qb. That is, it is possible to change the light color by changing the color mixture ratio of each color or to change the overall luminance. That is, the control circuit 2 can be used as a light control unit and a color control unit.

(Embodiment 2)
To perform display using the light guide plate 7 described in the first embodiment, as shown in FIG. 5, a display panel 8 provided with a display pattern is disposed so as to overlap the light guide plate 7. In FIG. 5, the light guide plate 7 is sandwiched between the display panel 8 and the reflection plate 9. The reflecting plate 9 is the same as that described in the first embodiment.

  In the present embodiment, the light emitting diode elements 1 are arranged in a sinusoidal manner so that the arrangement density changes in each region of the arrangement range so that one surface of the light guide plate 7 on which the display panel 8 is overlapped has uniform brightness. . That is, the arrangement density at the central portion in the longitudinal direction of the end surface of the light guide plate 7 is smaller than that at the peripheral portion. By employing such a configuration, it is possible to improve the uniformity of the brightness of the surface of the light guide plate 7.

  Here, the sinusoidal rule means that when the distance from the center of the arrangement range of the light emitting diode elements 1 is x, the density of the light emitting diode elements 1 is set so that a + sin (x / b · π) is satisfied. It is to be. a and b are constants. The light distribution in this case is as shown by the solid line in FIG. FIG. 6 shows the distance to the irradiation surface parallel to the surface on which the light emitting diode elements 1 are arranged as a unit distance, and the distance from the reference point facing the center of the arrangement range of the light emitting diode elements 1 in the irradiation surface as the unit distance. The result is shown on the horizontal axis after division.

  In FIG. 6, the arrangement range of the light-emitting diode elements 1 is ± 2, and a = 1.5 and b = 4. At this time, it was found that the illuminance difference was small in the range of ± 1.5, and that the illuminance suddenly decreased outside the range of ± 2.5. That is, uniform illuminance can be obtained in a place where the distance from the reference point is within a predetermined range on the irradiation surface.

  As a comparative example, the light distribution when the light emitting diode elements 1 are arranged at a uniform density on one plane is shown by a broken line in FIG. When the light-emitting diode elements 1 are arranged in the range of ± 2 similarly to the above-described configuration, the illuminance higher than the illuminance obtained at the position of ± 2.5 in the above-described configuration is obtained in the range of ± 3.5. However, the illuminance difference due to the distance is larger than in the above configuration.

  As is clear from the above description, it can be said that it is desirable to arrange the light emitting diode elements 1 according to a sinusoidal rule in order to obtain uniform illuminance within the target range of the irradiation surface.

  Further, when the light emitting diode elements 1 are arranged so as to be in close contact with each other, the temperature of the central part may be higher than that of the peripheral part due to heat generation of the light emitting diode element 1, but the arrangement density of the central part is higher than that of the peripheral part. The temperature difference between the central portion and the peripheral portion can be reduced by reducing the temperature. Such an arrangement can also be obtained with a sinusoidal rule as described above. When the temperature of the light-emitting diode element 1 rises, the light-emitting characteristics may change, or in some cases, the light-emitting diode element 1 may be destroyed. However, as described above, it is necessary to reduce the temperature difference between the central part and the peripheral part in the arrangement range. As a result, variations in light emission characteristics are reduced, and reliability is improved.

  The light emitting diode elements 1 may be divided into a plurality of groups, and the lighting state may be controlled for each group. In this case, a difference can be provided between the brightness of each region of the light guide plate 7. Here, by controlling the lighting state of the light emitting diode element 1 by employing the same configuration as the control circuit 2 of the first embodiment, the control circuit 2 can be used as a dimming unit.

  As shown in FIG. 7, by providing the terminal pins 5 arranged in the same manner as the fluorescent lamp, it becomes possible to use a normal fluorescent lamp socket. That is, it can be used in place of a display device using a fluorescent lamp and a light guide plate. Other configurations and operations are the same as those of the first embodiment.

(Embodiment 3)
In order to make the display pattern easier to recognize when the display panel 8 is provided as in the second embodiment, it is conceivable to increase the contrast of the display pattern. As a technique for increasing the contrast, it is desirable to arrange the light emitting diode elements 1 such that the greater the amount of transmitted light in the display pattern, the greater the amount of light leakage from the light guide plate 7. It should be noted that the increase / decrease of the amount of leaked light can also be controlled by the reflection plate 9.

  When the display pattern is colored as shown in FIG. 8 (the regions Dr, Dg, and Db are colored red, green, and blue in the illustrated example, respectively), the display pattern is shown in FIG. As described above, it is desirable to arrange the light emitting diode elements 1r, 1g, and 1b, which emit light having colors similar to those of the regions Dr, Dg, and Db, in the vicinity of the regions Dr, Dg, and Db. With this configuration, the color of the colored portion of the display pattern is clarified, the color contrast is enhanced, and the recognizability of the display pattern can be improved. Note that this configuration may be applied as needed.

It is a perspective view showing Embodiment 1. It is a principal part perspective view which shows the other example of Embodiment 1. FIG. 9 is a perspective view of a main part showing another example of the first embodiment. It is a circuit diagram same as the above. It is a top view showing Embodiment 2. It is operation | movement explanatory drawing same as the above. It is a front view same as the above. FIG. 10 is an exploded perspective view showing Embodiment 3. It is a perspective view same as the above.

Explanation of reference numerals

DESCRIPTION OF SYMBOLS 1 Light emitting diode element 1r, 1g, 1b Light emitting diode element 2 Control circuit 7 Light guide plate 8 Display panel 9 Reflector Dr, Dg, Db area

Claims (5)

  A light guide plate that leaks light introduced from the peripheral surface of the plate-like body from at least one of the front and back surfaces, and a plurality of light emitting diode elements that are arranged opposite to the peripheral surface of the light guide plate and have a plurality of emission colors. A light source using a light emitting diode.   Used in a lighting device provided with a display pattern on at least one of the front and back surfaces of the light guide plate, wherein light-emitting diode elements are arranged such that the amount of light leakage from the light guide plate increases as the amount of transmitted light in the display pattern increases. A light source using the light emitting diode according to claim 1.   Used in a lighting device provided with a display pattern on at least one surface of the front and back of the light guide plate, a plurality of light emitting diode elements of a plurality of emission colors to match the color of the colored portion in the display pattern and the light color leaking from the light guide plate The light source using the light emitting diode according to claim 1, wherein the light source is arranged.   2. A light source using a light emitting diode according to claim 1, wherein the light output of each of said light emitting diode elements is dimmed by dimming means.   The light emitting diode element is connected to each group so that the plurality of light emitting diode elements form a plurality of groups, and a lighting state of each light emitting diode element can be controlled for each group. Light source using a light emitting diode.

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