JP5518813B2 - Surface illumination light emitting device - Google Patents

Description

  The present invention relates to a surface illumination light-emitting device used for signboard backlight illumination, LCD backlight, signal display, vehicle display device, and the like.

  As a light source for a surface illumination light emitting device, an LED (light emitting diode) with low power consumption, high luminance and long life is being used, but the light emitted from the LED is highly directional and uniform over a wide area. It is difficult to obtain a light amount distribution.

  Therefore, in Patent Document 1, a large number of linear V-shapes in a direction perpendicular to the incident direction of light from the LEDs are within the entire area of the surface of the transparent acrylic plate in which a plurality of LEDs are arranged at regular intervals on the end. A configuration has been proposed in which grooves are arranged in parallel in parallel with each other, and incident light is scattered and reflected and diffused and refracted by the V-shaped grooves.

  In Patent Document 2, a light guide is disposed between a lamp housing having a light source housing for housing LEDs and a display plate covering the opening, and the inner wall surface of the lamp housing is subjected to embossing. A configuration has been proposed in which light from the LED is scattered inside the light guide, and the light irradiated on the inner wall of the lamp housing is diffusely reflected and scattered again inside the light guide.

  Further, in Patent Document 3, an inner surface of a casing having an opening and containing a point light source is used as a reflection surface, and a part of light provided at a portion blocking the opening on the point light source is transmitted and reflected and diffusely reflected. Uniform illumination light by limiting the amount of light in the central part emitted from the light emitting part with strong directivity by the outer reflective part and the light transmissive central reflective part having a higher reflectance than the outer reflective part The structure which obtains is proposed.

JP 7-270624 A JP 2003-186427 A JP 2011-049176 A

  However, in the configuration proposed in Patent Document 1, there is a hot spot (bright local area of light) due to the irradiation of LED light on the end face of the transparent acrylic plate, which is a light guide plate for introducing light, and brightness of surface illumination. Depending on the situation, the hot spot becomes conspicuous, and there is a problem that the illuminance uniformity of the surface illumination light cannot be secured.

  Further, in the configuration proposed in Patent Document 2, there is a problem that the apparatus becomes large because the lamp housing needs to have a certain height in order to obtain the illuminance uniformity of the illumination light.

In Patent Document 3, as shown in FIG. 8, a plurality of concentric slits 205a are formed immediately above the LED light source 203 (see FIG. 9) of the light transmitting substrate 204 that covers the upper surface opening of the rectangular box-shaped casing 202. The arrangement of arranging the light-shielding plate (radiation-side reflecting portion) 205 is proposed, but according to this, the slit 205a and the light-shielding portions are alternately distributed as shown in FIG. In particular, in the vicinity of the LED light source 203, since the area of the light shielding plate 205 is set large, the light is divided when the light passes through, and the difference in light intensity becomes stronger. As a result, a shadow is easily formed by the light shielding plate 205 , which adversely affects the uniformity of light intensity.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a surface illumination light-emitting device capable of making the light intensity distribution uniform over the entire area.

In order to achieve the above-mentioned object, the invention according to claim 1 is characterized in that an opening facing the bottom wall of a light guide box having a bottom wall and a side wall standing around the bottom wall is covered with a light transmission plate, In the surface illumination light-emitting device in which the inner surface of the bottom wall and the side wall of the light guide box is a reflection surface, and an LED light source is disposed on the bottom wall in the light guide box, the light source box is directly above the LED light source in the light guide box. A radial light shielding body is disposed on the LED light source, and the radial light shielding body is configured by a blind portion located immediately above the LED light source and a plurality of light shielding pieces extending radially outward from the periphery of the blind portion. characterized in that that.

The invention according to claim 2 is characterized in that, in the invention according to claim 1 , the light shielding piece is formed into a shape whose width becomes narrower as it goes away from the center of the blind portion in the radial direction.

According to a third aspect of the present invention, in the first or second aspect of the present invention, a hole is formed in a central portion of the blind portion of the radial light shield.

  According to the present invention, the highly directional light from the LED light source is shielded by the blind portion of the radial light shield, and even if there is a portion where direct light does not reach the light transmission plate, the light is reflected by the radial light shield. The light intensity is evenly mixed inside the light guide box due to the light guide effect due to the turbulence, so that the light with uniform intensity passing through the plurality of slits formed between the plurality of light shielding pieces of the light shielding body is light. The light is emitted from the entire surface of the transmission plate and used for illumination. That is, the plurality of light shielding pieces of the radial light shielding body function to correct mismatch between the light intensity around the blind portion and the light guide box by adjusting the balance between light reflection and transmission.

It is a sectional side view of the surface illumination light-emitting device concerning this invention. (A), (b) is a top view of the surface illumination light-emitting device based on this invention. It is a fragmentary perspective view which shows the light which permeate | transmits the slit of the radiation shielding body of the surface illumination light-emitting device which concerns on this invention. It is a figure which shows the light intensity distribution of the surface illumination light-emitting device based on this invention. It is a top view which shows another form of the surface illumination light-emitting device which concerns on this invention. It is a perspective view which shows another form of the surface illumination light-emitting device which concerns on this invention. It is a perspective view which shows another form of the surface illumination light-emitting device which concerns on this invention. It is a top view of the conventional surface illumination light-emitting device. It is sectional drawing which shows the light which permeate | transmits the slit of the surface illumination light-emitting device shown in FIG.

  Embodiments of the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a side sectional view of a surface illumination light emitting device according to the present invention, FIGS. 2A and 2B are plan views of the same surface illumination light emitting device, and FIG. FIG. 4 is a partial perspective view showing transmitted light, and FIG. 4 is a view showing a light intensity distribution of the same surface illumination light emitting device.

  As shown in FIGS. 1 and 2A, the surface illumination light-emitting device 1 according to the present invention includes a rectangular light guide box 2 having an open top surface. The light guide box 2 has a rectangular shape. The bottom wall 2 </ b> A and four rectangular side walls 2 </ b> B erected around the bottom wall 2 </ b> A are configured. Here, the inner surface of the bottom wall 2A and the side wall 2B of the light guide box 2 is subjected to reflection treatment, and each inner surface of the bottom wall 2A and the side wall 2B constitutes a reflection surface. As shown in FIG. 1, an LED light source 3 is disposed at the center of the light guide box 2, and light having high directivity is emitted upward from the LED light source 3. The inner surfaces of the bottom wall 2A and the side wall 2B may be constituted by, for example, a white reflecting surface that diffuses and transmits light.

  The upper opening of the light guide box 2 is covered with, for example, a white light transmission plate 4 that diffuses and transmits light, and the LED light source 3 directly above the LED light source 3 inside the light guide box 2. A radial light shielding body 5 for totally reflecting light from the LED light source 3 toward the LED light source 3 is disposed horizontally. As shown in FIG. 2A, the radial light shield 5 includes a circular blind portion 5A positioned immediately above the LED light source 3, and a plurality of radial light shields 5 extending radially outward from the periphery of the blind portion 5A. Each of the light shielding pieces 5B is formed in a needle shape whose width becomes narrower from the center of the blind portion 5A in the radial direction. Accordingly, a plurality of slits 5a extending radially outward are formed between the light shielding pieces 5B of the radial light shielding body 5, and the slits 5a are blind portions 5A opposite to the light shielding pieces 5B. The width increases as the distance from the center increases.

  In the surface illumination light emitting device 1 configured as described above, when light having strong directivity is emitted upward from the LED light source 3, the light is blinded by the radial light shield 5 disposed immediately above the light source. The light is totally reflected by 5A and diffused in the lateral direction while repeating reflection and scattering between the reflecting surfaces (inner surfaces) of the bottom wall 2A and the side wall 2B of the light guide box 2 and the radial light shielding body 5, as shown in FIG. As shown, the light passes through the slits 5a formed between the plurality of light shielding pieces 5B of the radial light shielding body 5, passes upward, passes through the light transmission plate 4, and is emitted upward to be used for illumination. Here, since each slit 5a is continuously formed so as to increase in width as the distance from the center of the blind portion 5A increases in the radial direction as described above, the light passing through the slit 5a is blocked on the way. There is no.

  Thus, the highly directional light emitted from the LED light source 3 is shielded by the blind portion 5A of the radial light shield 5, and even if there is a portion where the direct light does not reach the light transmission plate 4, the radial light shield. The light intensity is uniformly mixed inside the light guide box 2 by the light guide effect due to the reflection of light by 5 and the diffused radiation, so that the plurality of slits 5a formed between the plurality of light shielding pieces 5B of the radial light shielding body 5 are provided. The passing light having uniform intensity is emitted from the entire surface of the light transmission plate 4 and used for illumination. That is, the plurality of light-shielding pieces 5B of the radial light-shielding body 5 adjust the balance between reflection and transmission of light so that the light intensity between the periphery of the blind portion 5A of the radial light-shielding body 5 and the light intensity in the periphery of the light guide box 2 is reduced. Serves to correct inconsistencies.

  Here, the distribution of the light intensity (light relative intensity) of the surface illumination light-emitting device 1 according to the present embodiment is shown in FIG. 4. As is clear from FIG. 4, according to the surface illumination light-emitting device 1 according to the present invention. For example, a substantially uniform light intensity distribution can be obtained over the entire area.

  When the light intensity of the blind portion 5A portion of the radial light shielding body 5 is lower than the periphery of the light guide box 2, as shown in FIG. The light intensity is adjusted by inserting a slit 5b. The width of the slit 5b is as narrow as possible, and if the light intensity is insufficient, the number of the slits 5b may be increased to a symmetrical position. Thereby, uniform light emission is possible. Alternatively, the light intensity may be adjusted by making a small-diameter hole in the central region of the blind portion 5A. If the light intensity is insufficient, a plurality of holes 5c may be formed at symmetrical positions as shown in FIG. Alternatively, the light intensity may be adjusted by reducing the diameter of the blind portion 5A. On the contrary, when the light intensity of the blind portion 5A portion of the radial light shield 5 is higher than the periphery of the light guide box 2, the diameter of the blind portion 5A may be enlarged.

  Further, in the present embodiment, the plurality of light shielding pieces 5B of the radial light shielding body 5 are formed in needles extending radially linearly, but the light shielding pieces 5B may be bent in the same direction even if they are bent in the same direction. The shape may not be similar to the internal shape of 2. In the present embodiment, the shape of the light shielding piece 5B has been described as being needle-shaped. However, it is only necessary that the width becomes narrower as the distance from the radial direction increases, and the shape does not necessarily need to be acicular. For example, the shape which cut off the front-end | tip of a needle | hook etc. may be sufficient.

  By the way, the distance L1 between the radial light shield 5 and the light emitting surface (upper surface) of the light transmission plate 4 and the distance L2 (see FIG. 1) between the radial light shield 5 and the LED light source 3 are for obtaining the effect of the present invention. It becomes an important factor. Specifically, when the radial light shield 5 and the light transmission plate 4 are close to each other because the distance L1 is too small, the pattern of the radial light shield 5 is projected as a shadow on the light transmission plate 4 to increase the distance L1. This makes it easier to obtain a more uniform light intensity. If the distance L2 is too small, the amount of light beam that can be extracted decreases, and the amount of light beam that can be extracted can be increased by increasing the distance L2. However, if the distance L2 is too large, the light shielding effect by the radial light shield 5 is weakened.

  The height h of the light guide box 2 is (L1 + L2). From the above, the higher the height h of the light guide box 2, the greater the amount of light flux used for surface illumination and the uniformity of the light intensity. Is advantageous.

  However, when the height h of the light guide box 2 is limited, as shown in FIG. 6, the surface illumination light emitting device 1 shown in FIG. 1 and FIG. It is possible to adopt a configuration to In this case, as shown in FIG. 7, the partition which divides between each basic unit may be abbreviate | omitted.

  In addition, although the above embodiment demonstrated the form which arrange | positioned one LED light source 3 in the light guide box 2, you may arrange | position multiple LED light sources 3. FIG. In addition to air, the light guide box 2 may be filled with other substance media such as a liquid other than air or a solid.

DESCRIPTION OF SYMBOLS 1 Surface illumination light-emitting device 2 Light guide box 2A Bottom wall of light guide box 2B Side wall of light guide box 3 LED light source 4 Light transmissive plate 5 Radial light shield 5A Blind part of radial light shield 5B Radial light shield 5a Radial light shield Body slit 5b Radial light shield slit 5c Radial light shield hole h Height of light guide box L1 Distance between radial light shield and light transmission plate L2 Distance between radial light shield and LED light source

Claims (3)

An opening facing the bottom wall of the light guide box having a bottom wall and a side wall standing around the bottom wall is covered with a light transmission plate, and the bottom wall of the light guide box and the inner surface of the side wall are reflecting surfaces. In the surface illumination light-emitting device formed by arranging the LED light source on the bottom wall in the light guide box,
Arranging a radial light shield directly above the LED light source in the light guide box ,
The radial light shielding body is composed of a blind portion located immediately above the LED light source and a plurality of light shielding pieces extending radially outward from the periphery of the blind portion. Light emitting device. Surface lighting emitting device according to claim 1, characterized in that molding the light shielding piece to a shape in which the width becomes narrower as the distance in a radial direction from the center of the blind portion. Surface lighting emitting device according to claim 1 or 2, wherein the forming the hole in the center of the blind portion of the radial light shield.

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