JP4858241B2 - Lighting unit and lighting device - Google Patents

Description

  The present invention relates to an illumination unit using an LED (light emitting diode) and an illumination device using the illumination unit. In particular, the present invention relates to a flat light-emitting illuminating device such as a backlight of a liquid crystal panel used for information display such as a television or a personal computer, and an illumination unit used therefor.

  In recent years, the mainstream of television has shifted to thin large-screen televisions. There are two main types of display panels used in thin large screen televisions. One is a liquid crystal panel and the other is a plasma display panel. Of these, the liquid crystal panel does not have a function of emitting light by itself, and therefore requires a backlight illumination device. A large screen is the mainstream of LCD TVs, and a backlight illumination device for it has a large-area light emitting surface that conforms to the dimensions of the liquid crystal panel, and has uniform illumination and high brightness over the entire surface. Is required.

  Hereinafter, a conventional backlight illumination device used in a liquid crystal television will be described.

  The backlight illumination method of the liquid crystal panel is roughly classified into two methods. One of them is a side light system as disclosed in Patent Document 1, in which light emitting light sources (LEDs, cold cathode ray tubes, etc.) are arranged on either the top, bottom, left or right side of the panel (when the size of the liquid crystal panel is small) May be arranged at the corners), and distributes the light from the light source through the light guide plate made of a highly transparent material such as acrylic resin as uniformly as possible to the entire back surface of the liquid crystal panel. is there. Another method is a rear light method as disclosed in Patent Document 2, in which a light emitting light source (single or plural) is arranged immediately after (directly below) a liquid crystal panel, and a prism plate, a diffusion plate, etc. are used. In this method, the illuminance is uniformed as much as possible and the liquid crystal panel is illuminated from behind.

  When the size of the liquid crystal panel is relatively small, such as 15 to 16 inches or less, sufficient illuminance can be obtained by the above-mentioned sidelight method. It is difficult to obtain a satisfactory screen illuminance for a large-screen TV. In contrast, in the rear light system, since a plurality of cathode ray tubes or LED light source arrays can be arranged behind the liquid crystal panel, a liquid crystal screen with high illuminance can be obtained.

  Hereinafter, a conventional rear light emission light source will be described.

  Currently, a cold cathode ray tube is often used as a light source for the rear light system. Recently, with the progress of higher brightness of LEDs, three types of LEDs that emit single colors of red, green, and blue are used. The used LED light source has come to be used. Advantages of using the LED are that it has a long life, saves power, is easy to be reduced in size and thickness, and has excellent impact resistance against dropping and vibration. Furthermore, LEDs that emit monochromatic light in red, green, and blue have a high color purity of each monochromatic light, so that the color reproduction range can be widened.

  When using an LED as the light source of a backlight device for a color liquid crystal display, the illuminance must be averaged over the entire screen in addition to mixing the three primary colors of red, green, and blue into white light. However, in order for the three primary colors emitted from the LED to diffuse, mix appropriately, and make the illuminance uniform, an appropriate distance from the LED light source must be provided. FIG. 9 shows how the illuminance varies on the surface of the diffusion plate due to the difference in the distance from the LED light source to the diffusion plate.

  As shown in FIG. 9 (a), LEDs are mounted on a circuit board 50 as a set of LED chips 51a, 51b, 51c that emit red, green, and blue, respectively, and they are made of transparent resin 52 (hard silicone resin). Or epoxy resin). FIG. 10 shows a state where the LED 51 is bonded on the surface of the circuit board 50 and is covered with a transparent resin 52.

  FIG. 11 shows the light dispersion characteristics of the LED 51 configured as shown in FIG. As shown in this figure, most of the light rays emitted from the LED 51 have a characteristic of being emitted intensively in the front direction. When a diffuser plate having a uniform concentration is installed near the front surface of the LED 51 having such light dispersion characteristics, the so-called “eyeball phenomenon” in which the central portion shines brighter than the peripheral portion on the diffuser plate, as shown in FIG. "Appears. In this case, the diffusion plate becomes a secondary light emitting surface. In addition, when a plurality of LEDs having different emission colors are mounted, the color mixture of light is not sufficient and color unevenness occurs.

  Since the LED chips 51a, 51b, 51c shown in FIG. 9A are mounted close to each other, the three colors of red, green, and blue are mixed and become white light when a little away from the light source, but the illuminance is emitted. It will not be uniform unless it is far from the source.

  FIG. 9B shows the relative illuminance distribution when a diffuser plate is placed at a position S1 that is relatively close to the LED and the light from the LED is received as a secondary light emitting surface. At this position, the light from each light source is not sufficiently diffused, so there is a large unevenness in the illuminance distribution. When the diffuser plate is placed at the position S2 away from the light source, the relative illuminance distribution becomes uniform as shown in FIG. 9C. As described above, if the distance between the LED and the diffusion plate is increased, the eyeball phenomenon and the color unevenness are alleviated, but the depth becomes large and the thinning cannot be achieved.

  As described above, in the method of forming a uniform white illumination light source by separating the light source and the diffuser plate serving as the secondary light emitting surface, the entire liquid crystal display has a large depth, and the backlight device is configured by a cold cathode ray tube. And it will not change. In such a structure, the characteristics of the extremely small LED of the element are not fully utilized.

  Even if the distance between the LED chip and the diffusion plate is short, in order to eliminate the eyeball phenomenon and the color unevenness, it is necessary to perform sufficient reflection and diffusion between the spatial distances of the two.

  As a proposal for a thin and lightweight lighting device that takes advantage of the characteristics of LEDs, a lighting unit that uses three types of LEDs that emit red, green, and blue, and a thin, large-area lighting unit that uses multiple LEDs. A configuration example of the illumination device is disclosed in Patent Document 2.

  The lighting unit of the above disclosed example is shown in FIG. This illumination unit has a Fresnel concave mirror 61 having a plurality of concentric steps, and the concave surface space of the Fresnel concave mirror 61 is filled with a transparent resin 62 having a high degree of transparency and is formed in a predetermined shape. The surface of the transparent resin 62 (interface with air) is finished to be a smooth surface except for the central portion. At the center bottom of the Fresnel concave mirror 61, three LED chips 64 mounted on the circuit board 63 and emitting light of red, green and blue are arranged so as to be embedded in the transparent resin 62.

In the LED illumination unit formed as described above, among the light rays emitted from the LED chip 64, light close to the optical axis is emitted in the front direction (R61), but as the emission angle increases, the transparent resin 62 increases. Reflection on the surface increases, and all light rays exceeding the total reflection angle are reflected to the concave mirror 61 side. The reflected light beam repeats multiple reflections between the concave mirror 61 and the surface of the transparent resin 62, and is emitted to the outside while diffusing in the outer circumferential direction (R62 to 64). In the process of repeating multiple reflections, an illumination unit is disclosed in which three color light beams are mixed to become almost white light, and the color unevenness and the illuminance unevenness are small over the entire light emission area of the illumination unit.
JP 2003-297127 A JP 2006-148036 A

  Currently, thin large-screen TVs are the mainstream of TVs, and large-screen LCD TVs have a large share. In the future, backlight devices such as liquid crystal televisions must meet various demands such as power saving, high brightness, high color rendering, long life, low cost, light weight, impact resistance, and high speed response. A light-emitting diode as a light source is an optimal device to meet the above requirements. A large-area thin backlight device using the light-emitting diode, which is thin, lightweight, low-cost and good in color rendering, can be expected to greatly expand in the future and is very promising and useful.

  However, in the above disclosed example, first, the concave mirror 61 of a Fresnel reflecting member having a complicated step shape is used, and it is assumed that it takes considerable man-hours and costs to manufacture this. In addition, the entire area of the Fresnel reflecting member on the concave surface side is formed by close-contact molding of the transparent resin 62 by a method such as outsert molding, and it is estimated that this processing also requires a considerable cost.

  As a method of modeling the Fresnel reflection surface, a Fresnel reflection surface shape is integrally formed on one surface side of the transparent resin 62, and a reflective method such as aluminum or silver is applied to the surface by a method such as vacuum deposition or sputtering film formation. A method of forming a Fresnel reflecting surface by forming a metal thin film having a high rate is also promising. Although this method can be manufactured at a lower cost than using a separate reflecting member as described above, the method of forming a reflective film by vacuum deposition also increases the cleaning and adhesion strength of the substrate before vapor deposition. It is hard to say that the cost is low, considering the pre-treatment.

  In order to uniformly diffuse a light beam emitted from an LED chip, which can be said to be a point light source, with a small depth to a surface light source uniformly, it is necessary to skillfully combine diffuse reflection and diffusivity.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide an illumination unit and an illumination device that have less illuminance unevenness and color unevenness and are easy to assemble and low cost.

  In order to solve the above problems, an illumination unit of the present invention includes a light emitting diode and a diffuser plate disposed in front of the light emitting diode, and the diffuser plate has a diffuse reflectance with a diffuse reflectance that varies depending on a location. It has an inclined pattern.

  Further, the inclined pattern of the diffuser plate has a continuous inclination such that the diffuse reflectance decreases as the distance from the front surface of the light emitting diode increases.

  The inclined pattern of the diffusing plate has a gradually decreasing diffuse reflectance as the distance from the front surface of the light emitting diode increases.

  Further, the diffusion plate is made of a transparent material of a polymer material, and has fine irregularities formed on the surface, and the inclined pattern is formed by changing the density of the irregularities depending on the location.

  The diffusion plate is made of a transparent material of a polymer material, and the inclined pattern is formed on the surface by printing light diffusion material ink with a predetermined density pattern.

  The diffusion plate is obtained by printing the light diffusing material ink by ink jet printing or silk screen printing.

  Moreover, the said diffuser plate forms many inclination | tilt patterns by forming many microbubbles which scatter a light ray inside, and changing the density of this microbubble with a place.

  Further, a housing is provided which is disposed on the outer periphery of the light emitting diode and has a reflection surface for reflecting the reflected light from the diffusion plate.

  Further, the reflection surface formed on the housing is a diffuse reflection surface.

  Further, the reflection surface formed on the housing is a mirror reflection surface.

  Further, an antireflection film is applied to the surface of the diffusion plate.

  Further, a fine pitch Fresnel lens or microprism with positive optical power or negative optical power is formed on the surface of the diffusion plate, and the density of the Fresnel lens or microprism is changed depending on the location.

  Further, the light emission color of the light emitting diode and the color of the reflection surface formed on the housing are substantially the same color.

  In addition, the illumination device of the present invention is characterized in that a large number of illumination units are arranged and arranged.

  In addition, a second diffusion plate is installed on the front surface of the plurality of lighting units arranged and arranged with a predetermined space therebetween.

  The second diffusing plate has a diffusing function with a very thin layer thickness from the surface on the light emitting side.

  According to the illumination unit of the present invention, the illumination unit having a uniform illuminance distribution is simplified by including the diffuser plate having the diffuse reflectance gradient pattern in which the diffuse reflectance varies depending on the location on the front surface of the light emitting diode. This can be realized at low cost with simple components.

  In addition, according to the lighting device of the present invention, a large-area lighting device having a uniform illuminance distribution can be realized by installing the second diffusion plate in front of the plurality of lighting units arranged and arranged.

  Hereinafter, the best mode for carrying out the invention will be described with reference to the drawings.

(Embodiment 1)
FIG. 1 is an exploded perspective view of the lighting unit 1 according to the first embodiment. In FIG. 1, reference numeral 10 denotes a housing made of a milky white plastic molded product having a high diffuse reflectance. At the center of the housing 10, there is a circular hole 11 for the LED chip to enter, and a diffuse reflection surface 12 that is concavely curved toward the outer periphery is formed. The diffuse reflection surface 12 forms an almost parabolic surface. An outer peripheral wall 13 is formed on the four sides of the housing 10, and a special diffuse reflection film 20, which is a film-like or sheet-like diffuser plate, is stretched and bonded to the upper end surface 14. For bonding the housing 10 and the special diffuse reflection film 20, it is preferable to use an ultrasonic welding method.

  Reference numerals 31a, 31b, and 31c denote LED chips that emit red, green, and blue light, respectively, and are mounted on the surface of the circuit board 30 as shown in FIG. The three LED chips 31a, 31b, and 31c are protectively coated with a transparent resin 32 (heat resistant resin such as hard silicone resin and heat resistant epoxy resin).

  Since the LED chip has a high current density per volume, it generates a large amount of heat, and a mounting structure with good heat dissipation is indispensable. Efficient heat dissipation is indispensable for driving at higher luminance within the rated specification of the LED. For this reason, the circuit board 30 is made of an aluminum base. In order to further increase the heat dissipation efficiency, it is preferable to use a copper-based circuit board.

  For the special diffuse reflection film 20, instead of using a conventional uniform diffusion degree, for example, a plastic milky white sheet or film, a special diffusion film whose diffuse reflectance changes in a predetermined pattern is used as a diffusion member. Use.

  FIG. 3 shows an example of the special diffuse reflection film 20. In this example, an inclined pattern in which the diffuse reflectance gradually changes is formed concentrically. The darker the black part in the center near the front of the LED, the higher the diffuse reflectance. Accordingly, in the dark area, most of the incident light is diffusely reflected. Then, it is shown that the transmitted light increases and the diffuse reflectance decreases as the color becomes lighter away from the front surface of the LED.

  By optimizing the diffusion pattern formed on the special diffuse reflection film 20 and its diffusion gradient, the three colors of light emitted from the red, green and blue LED chips are mixed with white light having no color unevenness. At the same time, the illuminance can be made uniform, and a lighting unit having a target size can be realized.

  A difference in diffuse reflectance due to this region will be schematically described. FIG. 4 shows a diffuse reflection state in a region having a high diffuse reflectance (the dark black portion). When the light ray R is incident, most of the light ray is diffusely reflected and some of the light is transmitted through the film. To the other side. This region is a surface close to perfect diffuse reflection, and exhibits diffuse reflection that approximates a cosine distribution as shown.

  FIG. 5 shows a diffuse reflection situation in a region where the diffuse reflectance and transmittance are about half and half of the light ray R incident on this region is diffusely reflected on the lower surface side. The other amount of light is transmitted through the film and emitted to the upper surface side. As shown in FIG. 5, the transmitted light has an insulator-like diffusion shape extending in the traveling direction of the light.

  As described above, the special diffuse reflection film 20 is processed with a predetermined inclined pattern so that the diffuse reflectance continuously changes from a high diffuse reflectance to a low diffuse reflectance.

  Next, how the light rays emitted from the LED chips 31a, 31b, and 31c (collectively referred to as the LED 31) diffuse in the illumination unit 1 will be described with three examples.

  FIG. 6 shows a diagonal sectional view of the lighting unit 1 (for convenience of explanation, only one LED 31 is shown). The roughly circular shape and the lion-shaped figure in the drawing represent the light diffusion characteristics at that position, and the size of the figure showing the light diffusion characteristics shown in the figure is not proportional to the light intensity. Not a qualitative state.

  First, as shown in FIG. 6A, when the light ray R1 in the light ray group emitted from the LED 31 mounted at the center of the illumination unit 1 enters the position P1 near the center of the special diffuse reflection film 20, It is diffusely reflected at that position (first-order diffuse reflection) and diffused in all directions. A part of the light ray R1 passes through the special diffuse reflection film 20 and is emitted to the outside in a divergent manner. As described above, diffuse reflection is dominant in the vicinity of the center, and most of the amount of light diffuses into the internal space 40 of the lighting unit 1. When the light ray R2 is traced as one of the infinitely existing primary diffused light, the light ray R2 reaches the diffuse reflection surface 12 of the housing 10, and diffuse reflection (secondary diffuse reflection) occurs there. Furthermore, one of the secondary diffuse reflection light rays R3 reaches one point P2 of the special diffuse reflection film 20, and third-order diffuse reflection occurs at that position. A part of the light beam R3 is transmitted through the special diffuse reflection film 20 and radiated outward. As described above, the diffuse reflectance is different between the positions P1 and P2, and the ratio of the amount of light transmitted through the special diffuse reflection film 20 and emitted to the outside is greater at the position P2.

  Next, with reference to FIG. 6B, the situation when a light beam is incident around the middle of the special diffuse reflection film 20 will be described. Of the group of light rays emitted from the LED 31, when the light ray R4 travels to the position P3 of the special diffuse reflection film 20, it is diffusely reflected (primary diffuse reflection) at that position and diffused in all directions. A part of the light ray R4 is transmitted through the special diffuse reflection film 20 and radiated and emitted to the outside. When the light ray R5 is traced as one of the infinitely existing primary diffused light, the light ray R5 reaches the diffuse reflection surface 12 of the housing 10, and diffuse reflection (secondary diffuse reflection) occurs there. Further, one of the secondary diffuse reflection light rays R6 reaches one point P4 of the special diffuse reflection film 20, and third-order diffuse reflection occurs at that position. A part of the light ray R6 is transmitted through the special diffuse reflection film 20 and radiated outward. At the position P3, the amount of light that is transmitted through the special diffusive reflection film 20 to the incident light amount and radiated to the outside is about half.

  Next, with reference to FIG. 6C, the situation when a light ray enters the vicinity of the outer periphery of the special diffuse reflection film 20 will be described. In the group of light rays emitted from the LED 31, when the light ray R7 enters the position P5 near the outer periphery of the special diffuse reflection film 20, the characteristic of the special diffuse reflection film 20 is almost transparent at that position, and diffuse reflection at the position P5. Hardly occurs and is divided into a reflected ray R8 and a transmitted ray R9. The refractive index of the special diffuse reflection film 20 is about 1.5, and the light reflectivity is around 30% at the incident angle around the position P5. Accordingly, about 70% of the light ray R7 travels straight as transmitted light R9 and advances to the outside, and about 30% reaches the diffuse reflection surface 12 as reflected light ray R8, where diffuse reflection occurs and is emitted around the four sides.

  As described above, the light emitted from the LED is reflected and diffused innumerably between the special diffusion film 20 and the diffuse reflection surface 12, and each color light is mixed and turned into white light. Is averaged.

  In this way, the vicinity of the light emitting source (LED chip) has a high diffuse reflectance (low transmittance), and the special diffused reflection film 20 having a diffuse reflectance that decreases with increasing distance from the light emitting source (LED chip). Strong light rays are distributed and distributed to the outer periphery by diffuse reflection, and the illuminance is made uniform. Then, by setting the diffuse reflectance and the change inclination thereof optimally, it is possible to realize a high-efficiency lighting unit free from illuminance unevenness and color unevenness using a light emitting diode.

  In the present embodiment, as shown in FIG. 3, an inclined pattern in which the diffuse reflectance gradually changes depending on the location is formed on the transparent plastic film, and the special diffuse reflective film and the concavely curved diffuse reflector are used to make the thin This realizes an illumination unit with extremely little illuminance and color unevenness over a wide range even in the depth.

  In order to further increase the light emission efficiency of the illumination unit 1, it is effective to apply an antireflection film on the surface of the special diffuse reflection film 20. Since the refractive index of the film is about 1.5, the reflectance on one side of the film is about 4%. Therefore, by applying the antireflection film, the light emission efficiency can be improved by less than 4%.

  As a method for processing and forming the pattern of the special diffuse reflection film 20 described above, for example, a light diffusing material ink is printed on a transparent plastic film made of a polymer transparent material with a density change by silk printing or ink jet printing. Can be formed. Alternatively, it can be produced very easily and at low cost by forming fine irregularities on the surface of the film by changing the density. The shape of the inclined diffusion pattern can be easily changed in a very short time by using an ink jet printing method. Therefore, it is possible to respond quickly to specification changes, etc., and to easily develop product series.

  However, as a construction method that can be easily provided with a low loss, good diffuse reflection characteristics, and that the diffuse reflection characteristics can be continuously changed, and can be manufactured in a simple process, it is disclosed in Japanese Patent Application Laid-Open No. 2006-124499. It is extremely useful to use the composition materials and processing methods described.

  In the above disclosed example, by irradiating radiation energy (ultraviolet rays), countless fine bubbles (microbubbles) having a diameter of 1 to 10 μm can be generated in the material, and the amount of radiation energy to be controlled is controlled. This shows that the density of fine bubbles generated in the material can be adjusted. The amount of irradiation energy can be controlled by controlling either the light intensity or the irradiation time. Moreover, this composition can also be easily processed into a film form or a sheet form.

  As is well known, when fine bubbles are present in a transparent body (transparent plastic or the like), light rays are scattered by the bubbles, and the light transmittance decreases as the number of bubbles increases. When the number of bubbles becomes enormous, all light rays are scattered and the object becomes opaque, and the object itself is visually recognized as a white object because all the light rays are diffusely reflected (when the irradiated light is white light). When the size of the bubble is several times to a fraction of the light wavelength, diffuse reflection with extremely high whiteness can be obtained.

  Using a material obtained by processing the composition in the above disclosed example into a film, and exposing the composition film using a photomask whose light transmittance is a gradient pattern as shown in FIG. For example, a film having a diffuse reflectance gradient pattern as shown in FIG. 3 can be easily formed.

  Further, as another method of processing and forming the pattern of the special diffuse reflection film 20, a fine pitch Fresnel lens or micro prism having a positive optical power or a negative optical power is formed on the surface of the special diffuse reflection film 20, The density may be inclined.

  In the present embodiment, the diffuse reflectance change pattern is a concentric inclined pattern, but is not limited to this shape. For example, a pattern may be used in which the diffuse reflectance gradually decreases at predetermined intervals as the distance from the front of the LED increases. Patterns having various shapes, densities, gradation gradients, and steps can be easily generated by a computer, and an exposure photomask can be easily manufactured.

  Moreover, although the diffuse reflection surface 12 of the housing 10 is described by diffusing and reflecting light rays, a metal thin film having a high reflectance such as aluminum or silver is formed on this surface by vacuum deposition or sputtering, and the mirror surface. It can also be a reflective surface. By using a specular reflection surface, the diffusivity is lower than that of the diffuse reflection surface, so that the directivity of the light emission characteristic in the front direction is increased. Whether the diffuse reflection surface or the specular reflection surface is used may be selected according to the required specification of the illuminated object system.

  Moreover, it is desirable that the color of the diffuse reflection surface 12 of the housing 10 is substantially the same color as the emission color of the LED 31.

(Embodiment 2)
Next, FIG. 8 shows an illumination apparatus according to the second embodiment. FIG. 8A is a plan view of the lighting device, and FIG. 8B is a side view. In the second embodiment, a predetermined number of thin large-area planar illumination devices can be easily constructed by arranging and arranging a predetermined number of illumination units 1 as shown in FIG. 8A. When arranged in a grid, there is a concern that the space between the lighting units 1 will be slightly darker and a grid-like dark pattern will appear. However, as shown in FIG. ), There is a considerable amount of the light ray R9 that is emitted obliquely and straight (the light ray R9 that is emitted obliquely and comes from both adjacent lighting units 1). The space never gets dark.

  By the way, when constructing a large-area illumination device by arraying the illumination units 1, in order to make the illuminance more uniform, as shown in FIG. It is desirable to arrange the diffusing plate 2 across a space. By arranging the diffusing plate 2, the obliquely emitted light rays R <b> 9 are dispersedly emitted in the mutually adjacent space areas of the illumination unit 1, so that the decrease in illuminance in this air area is eliminated.

  The diffusing plate 2 may have a diffusing action over its entire thickness, but in order to reduce light loss within the plate thickness, the diffusion layer 2 should have a diffusing function with a very thin layer thickness on the surface of the light emitting side. It is preferable to use a diffuser plate. In addition, a micro lenticular lens or a micro prism can be formed on one side or both sides of the diffusing plate in order to shape the light beam direction of incident light or outgoing light.

  INDUSTRIAL APPLICABILITY The present invention is suitable for use as a backlight light source for a large-screen liquid crystal television by arranging a large number of LED illumination units to constitute a thin large-area planar light-emitting illumination device.

1 is an exploded perspective view of a lighting unit according to a first embodiment of the present invention. The figure which showed the mounting state of LED of the lighting unit The figure which showed the inclination diffuse reflection pattern formed in the special diffuse reflection film of the lighting unit The figure which showed the situation of diffuse reflection in the part with high diffuse reflectance of the special diffuse reflection film of the same lighting unit The figure which showed the situation of diffuse reflection in the part where the diffuse reflectance and transmittance of the special diffuse reflection film of the same lighting unit are about the same The figure explaining the optical path of the light ray radiated | emitted from LED of the illumination unit, and a diffuse reflection condition The figure which showed the shading pattern of the mask for exposure of the special diffuse reflection film of the illumination unit Configuration diagram of lighting apparatus according to Embodiment 2 of the present invention. A diagram explaining the difference in illuminance unevenness depending on the distance from the light source of the prior art to the diffusion plate Sectional drawing of the LED part mounted on the circuit board in the light emission source Light dispersion characteristics diagram of LED mounted on circuit board in the same light source Diagram showing “eyeball phenomenon” in the same light source Configuration diagram of prior art lighting unit

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Illumination unit 2 Diffusion plate 10 Housing 11 Circular hole 12 Diffuse reflection surface 13 Outer peripheral wall 14 Upper end surface 20 Special diffuse reflection film 30 Circuit board 31 LED
31a, 31b, 31c LED chip 32 Transparent resin 40 Internal space 51 LED
51a, 51b, 51c LED chip 52 Transparent resin 61 Fresnel concave mirror 62 Transparent resin 63 Circuit board 64 LED chip

Claims (12)

A light emitting diode, and a diffusion plate disposed in front of the light emitting diode,
The diffuser is to have a tilt pattern of diffuse reflectance diffuse reflectance varies depending on the location,
The diffusing plate includes a plurality of microbubbles that scatter light rays inside, and the inclined pattern is formed by changing the density of the microbubbles depending on the location . The lighting unit according to claim 1, wherein the inclined pattern of the diffusion plate has a continuous inclination such that the diffuse reflectance decreases with increasing distance from the front surface of the light emitting diode. The illumination unit according to claim 1, wherein the diffuse reflectance of the inclined pattern of the diffusing plate gradually decreases as the distance from the front surface of the light emitting diode increases. 2. The diffuser plate is made of a transparent material made of a polymer material, and has fine irregularities formed on the surface thereof, and the inclined pattern is formed by changing the density of the irregularities depending on locations. Lighting unit. The illumination unit according to claim 1, further comprising a housing disposed on an outer periphery of the light emitting diode and having a reflection surface for reflecting the reflected light from the diffusion plate. 6. The illumination unit according to claim 5 , wherein the reflection surface formed on the housing is a diffuse reflection surface. 6. The illumination unit according to claim 5 , wherein the reflection surface formed on the housing is a mirror reflection surface. The lighting unit according to claim 1, wherein an antireflection film is provided on a surface of the diffusion plate. 2. A fine pitch Fresnel lens or microprism with positive optical power or negative optical power is formed on the surface of the diffusion plate, and the density of the Fresnel lens or microprism is changed depending on the location. The lighting unit according to 1. 6. The lighting unit according to claim 5 , wherein the light emission color of the light emitting diode is the same as the color of the reflection surface formed on the housing. A lighting device comprising a plurality of lighting units according to claim 1 arranged in an array. The lighting device according to claim 11 , wherein a second diffusion plate is installed on a front surface of the plurality of lighting units arranged and arranged with a predetermined space therebetween.