JP2007018943A - Lamp unit and backlight device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lamp unit and a backlight device capable of obtaining uniform white light without color unevenness. <P>SOLUTION: This lamp unit 10 comprises at least one light emitting means 11, 12, 13 arranged facing an image forming surface 20c of a light guide plate 20 forming a part of a backlight light source, and emitting red, green and blue light respectively, and a lens part 18 for imaging the light emitted from the light emitting means 11, 12, 13, on the image forming surface 20c of the light guide plate 20 with a predetermined refractive index. The lens part 18 diffuses each light of red, green and blue colors almost uniformly over the whole of the same image forming region R on the image forming surface 20c. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a lamp unit and a backlight device for forming a backlight light source of a transmissive image device.

  In recent years, color liquid crystal panels have been widely used as display screens for mobile phones, digital video cameras, digital still cameras, liquid crystal displays for personal computers, liquid crystal televisions, and the like (see, for example, Patent Document 1). The liquid crystal panel does not emit light itself and outputs an image by changing the amount of light transmitted through the backlight for each pixel. The quality of the color reproducibility is determined by how wide the chromaticity of the backlight is. In particular, in a color liquid crystal panel using a three-color mixture of red (R), green (G), and blue (B) light emitting diodes (LEDs), good color reproducibility can be obtained.

  As shown in FIG. 5, a backlight using a three-color mixture of LEDs basically has a light source device (light emitting device) composed of a rectangular plate-shaped light guide plate 100 having a size of a liquid crystal display unit (not shown) and LEDs. Means) 102. In the case of a so-called side light system, the red LED 102 a, the green LED 102 b, and the blue LED 102 c of the light source device 102 are respectively disposed along the side end surface 100 a of the light guide plate 100. Light emitted from each of the LEDs 102 a to 102 c is incident from the side end surface 100 a of the light guide plate 100 that forms an image formation surface, and the traveling direction thereof is changed by reflection in the light guide plate 100 and is emitted from the main surface 100 b of the light guide plate 100. It has come to be. A reflection plate 104 is disposed on the back surface opposite to the main surface 100b of the light guide plate 100. The reflection plate 104 reflects light emitted from the main surface 100b of the light guide plate 100 to the back surface side. Light can be directed to the surface 100b side. Further, between the front side of the light guide plate 100, that is, between the main surface 100b of the light guide plate 100 and the liquid crystal display unit (not shown), diffusion for diffusing light emitted from the light guide plate 100. A plate 108 is interposed.

JP 2005-129242 A

  By the way, one of the most important issues in RGB-LED three-color mixing is to mix the three colors uniformly. As is clear from FIG. 5, the red LED 102a, the green LED 102b, and the blue LED 102c of the light source device 102 have different light emitting positions (in the figure, the emitted light from each LED is indicated by a broken line). Even if the central part can be whitened, the surrounding area is slightly red or blue, and after mixing the three colors, the color is slightly reddish and slightly bluish It becomes a whitish white.

  That is, in the conventional three-color mixing of RGB-LEDs, the light from each of the LEDs 102a to 102c having different light emitting positions is emitted at substantially the same radiation angle around the light emitting point, and Since only the image plane area is irradiated, color unevenness occurs, and uniform white light cannot be obtained over the entire image plane 100a. Therefore, there is a possibility that the quality of the display image is deteriorated.

  Furthermore, in the prior art, the diffuser plate 108 is provided to achieve light whitening, but there is a problem that light is attenuated by the diffuser plate and the light emission efficiency is lowered. Similarly, some light source devices attempt to diffuse light by dispersing a diffusing material such as silica in a resin material placed on each color LED 102a, 102b, 102c. In this case as well, light emitted from each LED is emitted. Since it attenuates, there is a problem that the light emission efficiency is lowered.

  The present invention has been made paying attention to the above circumstances, and an object of the present invention is to provide a lamp unit and a backlight device capable of obtaining uniform white light without color unevenness.

  The invention described in claim 1 is a lamp unit for forming a backlight light source of a transmissive image apparatus, and is disposed opposite to an imaging surface of a light guide plate forming a part of the backlight light source. A light emitting unit that emits red, green, and blue light, and a lens unit that forms an image of the light emitted from the light emitting unit on the imaging surface of the light guide plate with a predetermined refractive index. , Red, green, and blue lights are diffused substantially uniformly over the same imaging region on the imaging surface.

  The invention described in claim 2 is characterized in that, in the invention described in claim 1, the lens portion and the light emitting means are unitized by molding in a transparent resin.

  The invention described in claim 3 is the invention described in claim 1 or 2, wherein the lens portion is formed of a Fresnel lens.

  According to a fourth aspect of the present invention, in the invention described in the third aspect, the plurality of convex portions constituting the Fresnel lens are all at the same height in a region corresponding to a light source of one color. And

  The invention described in claim 5 is the invention described in claim 2, wherein the lens portion is formed of the transparent resin.

  A sixth aspect of the invention receives the light emitted from the lamp unit according to any one of the first to fifth aspects and the light emitting means of the lamp unit and emits backlight light for the transmissive image device. And a light guide plate.

  The lamp unit described in claim 1 includes a lens unit that diffuses each of red, green, and blue light substantially uniformly over the same imaging region on the imaging surface. The three colors can be uniformly mixed on the imaging surface of the light guide plate to form uniform white light. In addition, the presence of the lens portion eliminates the need for a conventional diffusion plate, so that attenuation can be reduced and emission efficiency can be increased. Therefore, it is possible to solve the problem of attenuation and size due to the diffusion material, which has been a problem in the past when eliminating color unevenness.

  According to the invention described in claim 2, the same effect as that of the invention described in claim 1 can be obtained, and the lens unit and the light emitting means are unitized by being molded in a transparent resin. As a result, assembly and handling become easy.

  According to the invention described in claim 3, the same effect as that of the invention described in claim 1 or claim 2 can be obtained, and since the lens portion is composed of a Fresnel lens, red, green and blue colors can be obtained. The unique function of the lens unit that diffuses each light substantially uniformly over the same imaging region on the imaging surface can be realized easily and effectively. In addition, since the Fresnel lens has the same function as a normal lens and is thin and light, it can be reduced in size and weight.

  According to the invention described in claim 4, the same effect as that of the invention described in claim 3 can be obtained, and the inclination angle and thickness of the protrusions can be made by making the heights of the plurality of protrusions the same. By changing the refractive index and changing the refractive index, the structure of the mold for molding the Fresnel lens can be simplified, and it is easy to manufacture and design and adjustment are easy.

  According to the invention described in claim 5, the same effect as that of the invention described in claim 2 can be obtained, and the lens portion is formed using a transparent resin that integrates the lens portion and the light emitting means. Therefore, it is possible to reduce the manufacturing cost by reducing the manufacturing process and the number of parts.

  The invention according to claim 6 can provide a backlight device capable of providing the same operational effects as the invention according to any one of claims 1 to 5.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. 1 to 3 show a lamp unit 1 according to an embodiment of the present invention. The lamp unit 1 constitutes a backlight device 10 for a transmissive image device together with a light guide plate 20 positioned opposite to the lamp unit 1.

  The light guide plate 20 is in the shape of a rectangular plate having the size of a liquid crystal display unit in a transmissive image device, a main surface 20a that emits backlight light, a back surface 20b opposite to the main surface 20a, a lamp It has a mixed-color imaging surface 20c that is a side end face that faces the unit 1 and forms images by mixing three colors (red, green, and blue) light emitted from the lamp unit 1.

  As shown in FIG. 4, the backlight device 10 includes the lamp unit 1 and the light guide plate 20, and a reflection plate 51 is disposed on the back surface opposite to the main surface 20 b of the light guide plate 20. The light emitted from the main surface 20b of the light guide plate 20 to the back side is reflected by the reflecting plate 51 to guide the light to the main surface 20b side, and a liquid crystal display unit (not shown) is provided on the main surface 20b side of the light guide plate 20. A lens sheet 53 is provided in between.

  In addition, as a material of the light guide plate 20, a translucent material such as an acrylic resin can be used. A light reflector (not shown) is disposed on the back surface 20 b side of the light guide plate 20.

  The lamp unit 1 is disposed opposite to the imaging surface 20c of the light guide plate 20 and emits red, green, and blue light respectively, and the light emitted from the light emitter A with a predetermined refractive index. The lens part B to be imaged on the 20 imaging surface 20c is formed by molding in a transparent resin 15 (for example, acid anhydride epoxy; refractive index about 1.4). The side wall of the resin 15 is confined with Cr plating.

  The light emitting means A is a so-called side light system, and includes a red LED chip 11, a green LED chip 12, and a blue LED chip 13 which are mounted on the driver LSI 30 and arranged in a line along the imaging surface 20 c of the light guide plate 20. Have. The driver LSI 30 is electrically connected to the Cu stems 32 and 33 plated with, for example, Ag (1 to 2 μm) via the wiring 19. These stems 32 and 33 are also embedded in the resin 15.

  The lens portion B is configured as a microlens portion 18 formed by patterning the resin 15 into a predetermined lens shape. The microlens unit 18 is opposed to the first Fresnel lens unit 18 a positioned facing the red LED chip 11, the second Fresnel lens unit 18 b positioned facing the green LED chip 12, and the blue LED chip 13. And a third Fresnel lens portion 18c.

  As shown in FIGS. 1 and 3, the Fresnel lens portions 18a to 18c are generally arranged in a single thin plate by cutting out the curved surface of a normal lens into an annular shape and forming an annular zone. (The surface of a spherical or aspherical lens is divided into concentric fine widths, and only the inclination angle is replaced with a prism on a flat surface), the spherical portion 40 located at the center and the concentric outer surface The first convex portion 42 having a substantially wedge-shaped annular shape and the second convex portion 44 having a substantially wedge-shaped annular shape concentrically positioned outside the first convex portion 42.

  Each Fresnel lens constituting the lens part B is extracted by a one-dot chain line in FIG. 3, and in the Fresnel lens part for one light source, each convex part 40, 42, 44 has a height H (structure depth). Are all the same, with different spacing and slopes. That is, it has a binary diffraction structure with heights of “1” and “0”, and the interval between the convex portions 40, 42, 44 changes continuously in consideration of the dispersion rate, the angle correction rate, and the like. Taking the structure. Note that, between the Fresnel lens portions 18a, 18b, and 18c with different light sources, the height H varies depending on the wavelength and the light intensity.

  As described above, since the thickness of the lens portion can be made uniform by configuring the Fresnel lens, the structure of the mold for molding the lens portion B can be simplified and can be easily manufactured and designed and adjusted.

  Each of the Fresnel lens portions 18a to 18c receives the red, green, and blue light from the LED chips 11, 12, and 13 facing each other on the imaging surface 20c of the light guide plate 20, respectively. The light diffused from the red LED chip 11 via the Fresnel lens portion 18a is indicated by a broken line, and diffused from the green LED chip 12 via the Fresnel lens portion 18b so as to be diffused substantially uniformly throughout the whole (see FIG. 2). The light diffused from the blue LED chip 13 via the Fresnel lens portion 18c is indicated by a solid line), its shape and size, and the LED chips 11, 12, 13 and the light guide plate A separation distance between 20 and 20 is set. In relation to this, in the case of the present embodiment, for example, the distance Y between the upper end of each LED chip 11, 12, 13 and the lower end of the microlens unit 18 is set to 1.00 mm, The distance X between the lower end and the imaging surface 20c is set to 2.00 mm. The width W of the lamp unit 1 is set to about 0.8 mm, the length L of the lamp unit 1 is set to about 7 mm, and the length l of the driver LSI 30 is set to 2.79 mm.

  As described above, the lamp unit 1 according to the present embodiment is a microlens that diffuses red, green, and blue light substantially uniformly over the same imaging region R on the imaging surface 20c of the light guide plate 20, respectively. Since the portion 18 (18a, 18b, 18c) is provided, the color unevenness can be eliminated, and the three colors can be uniformly mixed on the imaging surface 20c of the light guide plate 20 to form uniform white light. Further, the presence of the microlens portion 18 eliminates the need for the conventional diffuser plate 108 (see FIG. 5), so that the emission efficiency can be increased by reducing attenuation. Therefore, it is possible to solve the trade-off between the attenuation due to the diffusing material and the problem of size, which has been a problem in the past when eliminating the color unevenness.

  Further, the lamp unit 1 of the present embodiment is unitized by molding the microlens portion 18 (18a, 18b, 18c) as the lens portion and the LEDs 11, 12, 13 as the light emitting means in the transparent resin 15. As a result, assembly and handling are facilitated.

  Further, in the lamp unit 1 of the present embodiment, since the lens portion is composed of Fresnel lenses 18a, 18b, and 18c, red, green, and blue light are respectively spread over the same imaging region R on the imaging surface 20c. The unique function of the microlens unit 18 that diffuses substantially uniformly can be realized easily and effectively. In addition, since the Fresnel lens has the same function as a normal lens and is thin and light, it can be reduced in size and weight.

  Further, in the lamp unit 1 of the present embodiment, since the microlens portion 18 is formed using the transparent resin 15 that integrates the microlens portion 18 and the LEDs 11, 12, and 13, the manufacturing process and the number of parts are reduced. As a result, the manufacturing cost can be reduced.

  Needless to say, the present invention is not limited to the above-described embodiments, and can be variously modified without departing from the scope of the invention. For example, in the above-described embodiment, the side light system in which the LEDs 11, 12, and 13 are arranged to face each other along the side end portion of the light guide plate 20 is employed. A direct illumination form in which LEDs are arranged can also be adopted.

  In the above-described embodiment, only one set of the three color LEDs 11, 12, and 13 is provided. However, a plurality of LED sets may be provided depending on the application. Moreover, in embodiment mentioned above, although each LED11,12,13 is arranged in a line, the arrangement | sequence form of LED is arbitrary, For example, you may arrange | position LED in a matrix form.

  The lamp unit 10 is not limited to providing each of the red, green, and blue LEDs 11, 12, and 13. For example, the lamp unit 10 may have any color such as two red LEDs, two greens, and one blue. A plurality of LEDs may be provided.

  Further, the lamp unit 10 may have a color (intermediate color) having an intermediate wavelength spectrum of each color, for example, an orange color, in addition to the three colors of LEDs 11, 12, and 13 of red, green, and blue. Good.

1 is a schematic perspective view of a backlight device according to an embodiment of the present invention. It is a figure which shows schematically the illumination aspect of the backlight apparatus of FIG. It is a figure which shows the shape of a Fresnel lens part concretely. It is a perspective view which shows roughly the structure of the backlight apparatus which concerns on this Embodiment. It is a perspective view which shows the structure of the conventional backlight apparatus roughly.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Lamp unit 10 Backlight apparatus 11, 12, 13 LED chip (light emission means)
15 Resin 18 Micro lens part (lens part)
18a, 18b, 18c Fresnel lens portion 20 Light guide plate 20c Imaging surface

Claims (6)

  A lamp unit for forming a backlight light source of a transmissive image device, which is disposed facing an imaging surface of a light guide plate that forms a part of the backlight light source, and emits red, green, and blue light. A light emitting unit that emits light; and a lens unit that forms an image of light emitted from the light emitting unit on the imaging surface of the light guide plate with a predetermined refractive index. The lens unit emits red, green, and blue light. A lamp unit characterized in that each lamp unit diffuses substantially uniformly over the same imaging region on the imaging surface.   2. The lamp unit according to claim 1, wherein the lens unit and the light emitting means are unitized by being molded in a transparent resin.   The lamp unit according to claim 1, wherein the lens unit includes a Fresnel lens.   4. The lamp unit according to claim 3, wherein the plurality of convex portions constituting the Fresnel lens are all at the same height in a region corresponding to a light source of one color.   The lamp unit according to claim 2, wherein the lens portion is formed of the transparent resin. A lamp unit according to any one of claims 1 to 5, and a light guide plate that receives light emitted from the light emitting means of the lamp unit and emits backlight light for a transmissive image device. The backlight device.

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