JP4668131B2 - Light guide plate and lighting device - Google Patents

Description

  The present invention relates to a light guide plate and an illumination device including the light guide plate, and more particularly to an LED illumination device in which a phosphor is applied to the light guide plate.

  2. Description of the Related Art Conventionally, as an indoor or outdoor illumination device, an illumination device (for example, a fluorescent lamp) is known which generates light by exciting a phosphor with an LED and uses it as an illumination light source. For example, when white light is generated and used as an illumination light source, a combination of a phosphor and an LED includes a combination of a yellow phosphor and a blue LED (blue light).

  However, in a configuration in which light only passes through the phosphor, the fluorescence intensity varies greatly depending on the thickness of the phosphor. This will be described with reference to FIG. FIG. 7 is a graph showing calculation results of the phosphor film thickness and the fluorescence intensity when the absorption coefficient of the excitation light by the phosphor is 500 / cm and the absorption coefficient by the fluorescence phosphor is 50 / cm. the vertical axis represents fluorescence intensity and the horizontal axis represents the phosphor film thickness. A curve X shows the phosphor film thickness dependence of the fluorescence intensity in the reflection structure, and a curve Y shows the phosphor film thickness dependence of the attenuation of the excitation light when the excitation light passes through the phosphor.

  As shown in FIG. 7, in the curve X, the fluorescence intensity is not substantially changed if the phosphor film thickness is a certain thickness or more, but in the curve Y, the phosphor film thickness dependency is large. The strength is also lowered. Therefore, in the configuration in which the transmission of excitation light occurs, precise control of the phosphor film thickness is required, but there is a problem that it is difficult to control the phosphor film thickness.

  Therefore, in Patent Document 1, in the LED illumination device, the reflection surface disposed opposite to the ultraviolet emission surface of the ultraviolet LED module is provided with a reflecting mirror coated with a phosphor, so that the fluorescence intensity depends on the film thickness. A technique for reducing the size is disclosed.

  Incidentally, in addition to the indoor lighting device, the lighting device includes a backlight as a lighting device that emits light from behind the liquid crystal panel in the liquid crystal display device.

  The backlight uses a configuration in which light is incident on a light guide plate and guided to efficiently emit light from a predetermined range and irradiate the liquid crystal panel with light. Therefore, since this backlight is intended to irradiate light, it can be used as an illumination device that irradiates a room like a general fluorescent lamp.

  Here, an edge type will be described as a conventional backlight.

  In the edge type backlight, a transparent acrylic plate provided behind the liquid crystal panel is used as a light guide, and a light source is provided at one end thereof. The liquid crystal panel is irradiated with light from the surface of the acrylic plate on the liquid crystal panel side using multiple reflection inside the light guide.

  FIG. 8 is a schematic view showing a cross section of the liquid crystal display device 100 having an edge type backlight. As shown in the figure, the liquid crystal display device 100 includes an illumination device 110, a reflection sheet 120, and a liquid crystal panel 130. The illumination device 110 includes an edge light 111, a transparent acrylic plate 112, and a light scattering portion 113.

  Hereinafter, the surface of the acrylic plate 112 on which light from the edge light 111 is incident is referred to as a surface 112a. The surfaces of the acrylic plate 112 that are parallel to the display surface of the liquid crystal panel 130 are referred to as a surface 112b and a surface 112c in this order from the liquid crystal panel side. Further, the surface opposite to the surface 112a of the acrylic plate 112, and the surface 112d.

  The light emitted from the edge light 111 is incident on the acrylic plate 112 through the surface 112a. The light incident on the acrylic plate 112 is repeatedly totally reflected on the surfaces (112b and 112c) (that is, the boundary surfaces) and guided to the surface 112d. Further, a part of the totally reflected light is scattered by the light scattering portion 113 provided on the surface 112c. Of the scattered light, light that does not cause total reflection on the surface 112b of the acrylic plate 112 is emitted from the surface 112b toward the liquid crystal panel 130.

  For example, as shown in FIG. 9, the light scattering portion 113 is configured by a pattern made up of a plurality of circular figures. FIG. 9 is an enlarged view showing a part of the pattern of the diffusion portion on the acrylic plate 112.

  In the circular figure, the radius of the circle is set larger as the centers are arranged at regular intervals and are located farther from the surface 112a. In other words, the farther from the edge light 111, the larger the radius of the circle. This is due to the following reason.

  The amount of light incident on the acrylic plate 112 from the edge light 111 decreases as the light is guided. Therefore, as described above, it is possible to prevent a decrease in the amount of scattered light by increasing the radius of the circle as the distance from the surface 112a increases. Therefore, it is possible to irradiate a uniform light from the surface 112b. For these reasons, the radius of the circle is changed in order as described above.

  The reflection sheet 120 is a member for returning the light leaked from the surface 112 c excluding the portion corresponding to the light scattering portion 113 to the acrylic plate 112. Thereby, increasing the amount of light to be irradiated to the liquid crystal panel 130.

  Moreover, the following patent documents 2 and 3 are disclosed as light guide plates for obtaining white light emission.

  In Patent Document 2, in order to extract white light in a light guide plate device, a phosphor is applied to a concave portion formed on the back surface of the light guide plate into which light is introduced, and LED light is incident from the side surface of the light guide plate. A technique is disclosed in which white light emission is enabled by reflecting the light on a phosphor.

Further, in Patent Document 3, when a plurality of phosphor sheets are used in order to obtain white light emission in a light emitting device, the light emission surface includes a phosphor sheet laminated structure that facilitates multilayer lamination and easy color matching. Technology is disclosed.
JP 2006-59625 A (published March 2, 2006) JP 2003-36714 A (published on February 7, 2003) JP 2004-164977 A (published on June 10, 2004) Japanese Unexamined Patent Publication No. 2006-12868 (released on January 12, 2006) Hitachi Chemical Technical Report No.42 (2004-1)

  However, in the said patent document 1, since a light source is ultraviolet light, in order to cut the direct light from the light source which was not converted with fluorescent substance, there exists a problem that a UV cut filter must be provided. Moreover, since it is set as the structure which irradiates indirect light for the general illumination used indoors, when irradiating light with the widest emission area as bright as possible, there exists a problem that it cannot use suitably.

  Further, the conventional edge type backlight has the following problems when the acrylic plate is enlarged in the light guiding direction (that is, when the length L in FIG. 9 is increased).

  That is, when the radius of the circle (black circle in the figure) is increased as in the pattern before the enlargement, the shape of the circle is completely crushed near the surface 112d from a certain position, and from the surface 112b. Has a problem that it cannot emit light uniformly.

  Further, it is conceivable to increase the size by arranging a plurality of lighting devices 110 shown in FIG. 8 in a certain direction as shown in FIG. However, in this case, since the edge light 111 is arranged between the two acrylic plates, it is difficult to align the arrangement of the lighting devices 110 at a desired position with high accuracy. Therefore, there is a problem that it is difficult to apply to enlargement of the light emitting surface.

  In addition, in Patent Documents 2 and 3, since the purpose is to obtain white light emission, no countermeasure is disclosed for changes in fluorescence intensity due to attenuation of excitation light when excitation light passes through the phosphor. Absent.

  The present invention has been made in view of the above-described conventional problems, and its purpose is to make the light emitting surface uniform and to increase the size of the light emitting surface, and to efficiently extract and use light of a specific color. It is in providing the light-guide plate which can do.

In order to solve the above problems, the light guide plate of the present invention guides predetermined light incident from a predetermined direction along the light output surface and emits the light from the light output surface to the outside. In the light guide plate comprising: a light input unit that bends external light incident from the opposite side of the light exit surface in the predetermined direction and enters the light guide unit; The phosphor film for converting the wavelength of at least a part of the light irradiated on the reflecting surface to the reflecting surface on which the external light is incident to another wavelength and transmitting a part of the light Is applied, and light of a desired color is generated by color mixture of light having a wavelength converted and light having a wavelength not converted, and the light of the desired color is input to the light. The coating thickness of the phosphor film is adjusted so that it enters the light guide part from the part. It is characterized in that it is.

  According to the above configuration, the light input unit is incident on the light guide unit by causing the external light incident from the opposite side of the light exit surface to be bent in a predetermined direction and enter the light guide unit. Light is emitted from the light exit surface to the outside while being guided along the light exit surface. Therefore, the light guide plate itself can be thinned.

In addition, since the external light is guided along the light exit surface in the light guide unit, it is possible to install a light source that emits external light near the surface opposite to the light exit surface of the light guide plate. Furthermore, since it is not necessary to install a light source at the edge portion of the light guide plate, it is possible to easily combine the light emitting surfaces in a matrix form as compared with the conventional edge type backlight configuration. For this reason, it is possible to easily enlarge the light emitting surface. Further, the light input unit has a reflection surface on which external light is incident. Since the phosphor film that converts light into other wavelengths and transmits part of the light is applied, the light whose wavelength is converted and the light that is not converted are emitted in all directions. Are mixed, and the light of the mixed color is emitted to the light guide.

  Therefore, it is possible to extract light of a specific color desired by mixing light, and it is possible to send external light to the light guide unit more efficiently, that is, efficiently without unevenness. For this reason, uniform light emission can be obtained.

As described above, the light guide plate of the present invention can make the light emitting surface uniform and enlarge the light emitting surface, and can efficiently extract and use light of a specific color .

Also, the light guide plate of the present invention, among the light irradiated on the reflecting surface to produce a light of a desired color by mixing the light light and wavelength wavelength has been converted is not converted, the desired color so that light incident on the light guide portion from the light input portion, that has a coating thickness of the phosphor layer is adjusted.

  Thus, by adjusting the coating thickness of the phosphor film, it becomes possible to control the mixing ratio of the light generated from the light input portion to the light whose wavelength is converted and the light which is not converted. It becomes possible to obtain the light of the color which does. For example, even white light desired in an indoor or outdoor lighting device can be easily obtained.

Moreover, the light guide plate of the present invention includes a light guide unit that guides predetermined light incident from a predetermined direction along the light output surface and emits the light from the light output surface to the outside. The light input unit includes: a light input unit configured to bend the external light incident from the opposite side of the light emitting surface in the predetermined direction and enter the light guide unit; The incident reflection surface is coated with a phosphor film that converts at least some of the light emitted to the reflection surface into light of other wavelengths and transmits some of the light. Of the light applied to the reflecting surface, light of a desired color is generated by mixing light of which wavelength is converted and light whose wavelength is not converted, and the light of the desired color is guided from the light input unit to the light guide. to be incident on the portion, characterized in that the coating area of the phosphor film is adjusted It is.

  Thereby, by adjusting the coating area of the phosphor film, it becomes possible to control the mixing ratio of the light converted from the wavelength and the light not converted, from the light input portion. Color light can be obtained. For example, even white light desired in an indoor or outdoor lighting device can be easily obtained.

In the light guide plate of the present invention, it is preferable that the reflecting surface transmits a part of light irradiated to the reflecting surface.

  In order to solve the above problems, an illumination device of the present invention includes the light guide plate and a light emitting element that emits external light, and the light emitting element has a light emitting surface on a light emitting surface that is a reflecting surface of the light input unit. It is characterized by being disposed in a position facing the free side.

  According to said structure, it becomes possible to show | play the effect acquired with the light-guide plate mentioned above also with an illuminating device. In addition to obtaining indoor illumination with uniform light emission, the light emitting surface can be increased in size, so that it can be suitably used in large outdoor lighting.

  In the lighting device of the present invention, the external light is preferably light emitted from a light emitting diode or a semiconductor laser. This makes it possible to use a general-purpose light emitting diode or semiconductor laser as a light source that emits external light, without requiring a special light source, so that a lighting device can be obtained at low cost. .

As described above, the light guide plate of the present invention includes the light input unit that bends the external light incident from the opposite side of the light emitting surface in a predetermined direction and enters the light guide unit. The fluorescent light that converts the wavelength of at least a part of the light irradiated to the reflecting surface to the reflecting surface on which the external light is incident and converts the wavelength of the light to another wavelength and transmits a part of the light. By applying the body film, the external light incident from the opposite side of the light emitting surface is applied to the light guide unit as light of a specific color in which the light whose wavelength is converted and the light which is not converted are mixed. Since the light is incident, the light incident on the light guide unit is guided along the light exit surface, and is emitted to the outside from the light exit surface , and the wavelength of the light applied to the reflection surface is converted. The desired color is generated by mixing the light and the light whose wavelength is not converted. As light is incident on the light guide portion from the light input portion, the coating thickness of the phosphor film is adjusted. Accordingly, the light emitting surface can be made uniform and the light emitting surface can be enlarged, and a light guide plate that can efficiently extract and use light of a specific color can be provided.

  An embodiment of the present invention will be described as follows.

  Initially, the structure of the illuminating device 1 of this Embodiment is demonstrated, referring FIGS. Next, the optical path of light in the illumination device 1 will be described. The lighting device 1 is a commonly used indoor or outdoor lighting device such as a fluorescent lamp.

  FIG. 1 is a perspective view showing a schematic configuration of a lighting device 1 according to the present embodiment. FIG. 2 is an enlarged cross-sectional view illustrating the configuration of the surfaces 13 a and 13 b of the bent portion 13 of the light guide plate 2. FIG. 3 is a cross-sectional view showing the configuration of the light guide plate 2 as viewed in the direction of arrows AA in FIG. FIG. 4 is a top view showing the arrangement of the LED unit 3.

  As shown in FIG. 1, the illumination device 1 of the present embodiment includes a light guide plate 2 and an LED unit 3, and guides light emitted from the LED unit 3 to a desired range by the light guide plate 2. This is an LED illumination device that emits light.

  Here, the light guide plate 2 is a component that can be integrally formed, for example, by processing one transparent substrate and performing a surface treatment on the processed substrate. However, hereinafter, for convenience of explanation, the structure of the light guide plate 2 will be described by dividing the light guide plate 2 into a plurality of parts.

  As shown in FIG. 1, the light guide plate 2 includes a light guide part 11, a light guide part 12, and a bent part 13 (light input part). Further, the bent portion 13 is surrounded by the light guide portion 11 and the light guide portion 12. In the following description, for the sake of convenience of description, the light guide part 11 and the light guide part 12 will be described as having shapes that are symmetrical with respect to the bent part 13.

  The light guide 11 has surfaces 11a to 11h and has a substantially rectangular parallelepiped shape. The surface 11a (light emission surface) is a surface on the irradiation side, and the surface 11b is a surface on the LED unit 3 side. The surfaces 11c to 11f are surfaces that are adjacent to the bent portion 13 and exposed to the outside, and are formed as surfaces 11d, 11c, and 11e in this order from the front surface in the drawing. Further, the surface 11d and the surface 11e face each other with the bent portion 13 interposed therebetween. The surface 11f is a surface opposite to the surface 11c. The front surfaces 11g and 11h are the remaining surfaces, and the front surface in the figure is the front surface 11g and the back surface is 11h.

  The surfaces 11f to 11h are inclined toward the bent portion 13 with respect to the surface 11a. That is, the angle between the surfaces 11f to 11h and the surfaces 11a and 11b is inclined so that the angle formed with the surface 11b is larger than the angle formed with the surface 11a. This is merely a preferred configuration for the present embodiment, and is not limited to this, and may be a right angle case.

  The light guide unit 12 includes surfaces 12a to 12h at the same positions as the light guide unit 11, respectively. That is, the surfaces 12a to 12h correspond to the surfaces 11a to 11h of the light guide unit 11, respectively. In addition, the surface 12a corresponds to the light emission surface described in the claims, similarly to the surface 11a.

  The light guides 11 and 12 are made of the same material, and at least the insides of the light guides 11 and 12 are made of a material capable of guiding light, for example, a transparent acrylic material or glass material. The

  Further, when light is guided in the light guide portion 11, the scattering portions are formed on the surfaces 11b and 11f to 11h in order to improve the uniformity of the light. This will be described with reference to FIG. In FIG. 3, the light guide unit 11 side is illustrated, but a scatterer is similarly formed in the light guide unit 12 symmetrically with respect to the bent portion 13.

  The surface 11b of the light guide 11 has a predetermined pattern for scattering light. An example of this pattern is the pattern shown in FIG. However, the pattern is not limited to the pattern shown in FIG. 9, and various known patterns can be applied. The pattern may be any pattern as long as the figure constituting the pattern becomes larger as the distance from the surface 11c increases. In the following, the figure is referred to as a light scattering portion. Moreover, the area | region except the light-scattering part of the surface 11b is called a non-scattering area | region.

  A reflective material that reflects light or a scattering material that scatters light is applied to the surfaces 11 f to 11 h of the light guide unit 11. For example, a white paint may be applied to each surface. Moreover, the part to which the reflective material or the scattering material is applied is referred to as a light scattering portion.

  As shown in FIG. 1, the bent portion 13 includes surfaces 13a and 13b and an inner surface 13c. The surface 13a (reflection surface) is a surface on the LED unit 3 side and is a surface adjacent to the surfaces 11c to 11e of the light guide unit 11. The surface 13b (reflection surface) is a surface on the LED unit 3 side and is a surface adjacent to the surfaces 12c to 12e of the light guide unit 12. The inner surface 13c is a surface on the irradiation side. The surface 13a and the surface 13b are adjacent to each other, and the intersection line is parallel to the surface 11c of the light guide 11 and the surface 12c of the light guide 12. Further, the light guide unit 11 and the light guide unit 12 have been described as having a shape that is symmetrical with respect to the bent portion 13, but the bent portion 13 is formed on the light guide plate 2. It is preferable to be provided at the center.

  Moreover, the surface 13a * 13b has the same shape. Furthermore, as shown in FIG. 3, when the surface that is perpendicular to the surfaces 11 a and 12 a and passes through the intersection line is a first virtual surface, the surface 13 a and the surface 13 b are in relation to the first virtual surface. Thus, they are inclined at a predetermined angle (θ) in opposite directions.

  Moreover, the bending part 13 is comprised with the material in which the inside and the inner surface 13c can guide light. Further, as shown in FIG. 2, the surfaces 13a and 13b are formed of a reflective layer made of a material that reflects light (for example, aluminum). The reflective layer is preferably a film having a high reflectance with respect to the entire visible light spectrum, and may be silver or white resin in addition to aluminum.

  In order to prevent the shadow of light from being generated by the bent portion 13, the surfaces 13a and 13b are made of a material that transmits light a little (for example, white paint), or a reflector that completely blocks light. In the case of (for example, aluminum), it is preferable to have a structure in which light is leaked from a part of the bent portion 13.

  In the manufacture of the bent portion 13, for example, an acrylic plate is formed in the shape shown in FIG. 1, and then aluminum is vapor-deposited on the surfaces 13a 'and 13b' before forming aluminum to form the surfaces 13a and 13b. That's fine. Alternatively, aluminum may be deposited on a region corresponding to the reflective region (that is, the surfaces 13a 'and 13b'), and then the aluminum corresponding to the transmissive region may be removed.

  Further, after the surfaces 13a and 13b of the bent portion 13 are formed of a material that reflects light, the phosphor 15 is applied thereon.

  The phosphor 15 has a material that converts the wavelength of the irradiated light when irradiated with light. Specifically, the light passing through the phosphor 15 is converted into fluorescence and generated in all directions. Examples of the phosphor 15 include a yellow phosphor (such as YAG and ZnSe), a green phosphor (such as β-sialon), a red phosphor (such as calcium, aluminum, and silicon trinitride), and a blue phosphor. . In this embodiment, in order to obtain light of a desired color, it is appropriately selected.

  As mentioned above, the light guide part 11, the light guide part 12, and the bending part 13 process these three members by processing (cutting) one transparent plate (acrylic board etc.) and performing surface treatment etc., for example. What is necessary is just to manufacture integrally. Moreover, each light guide part 11 * 12 and the bending part 13 may be formed separately, and each part may be joined, and the light guide plate 2 may be comprised.

  Moreover, the shape of the light guide part 11 and the light guide part 12 is not limited to the shape mentioned above. To the last, the light guide part 11 and the light guide part 12 should just be set so that the area of a reflective surface is large, so that the distance from the bending part 13 is at least.

  The LED unit 3 (light emitting element) is composed of a light emitting diode (hereinafter, blue LED) that emits blue (B). In addition, as shown in FIG. 1, the blue LED has a light emitting surface of the blue LED at a position where the surfaces 13 a and 13 b of the bent portion 13 are not opposed to the surfaces 11 a and 12 a, as shown in FIG. 4. And on the first imaginary plane and on the center point of the intersection line.

  Here, when obtaining white light from a blue LED, there are a method using a yellow phosphor and a method using a green phosphor and a red phosphor. When the above is combined, light can be mixed to obtain white light.

  Further, the LED unit 3 may use a light emitting diode that emits ultraviolet light (hereinafter referred to as an ultraviolet light LED). In this case, white light is obtained by using a blue phosphor, a green phosphor, and a red phosphor. Is possible. In addition, the combination of the said LED and fluorescent substance is a case where white light is obtained, and it is also possible to obtain a desired color by combinations other than the above, and is selected suitably.

  Furthermore, the number of light emitting diodes used in the LED unit 3 is not limited to one, and a plurality of light emitting diodes may be provided. In the case of providing a plurality of light emitting diodes, the light emitting surfaces thereof are on opposite sides of the surfaces 13a and 13b of the bent portion 13 that are not on the surfaces 11a and 12a, and are on the first virtual surface and the intersections. It is preferable to collect and arrange near the center point of the line.

  By the way, in the sense that the phosphor is brought closer to the light source, it is generally considered to mix the phosphor with the resin protecting the LED chip, but in that case, the LED portion 3 to the surfaces 13a and 13b of the bent portion 13 are used. Variations occur in the optical path up to and, in fact, the color of the light changes depending on the viewing direction. Therefore, in the light guide plate 2 of the present embodiment, the fluorescent material 15 is applied with a certain thickness on the reflecting surface, that is, the surfaces 13a and 13b of the bent portion 13, so that the generated fluorescence is efficiently extracted and used. At the same time, the color does not change even if the viewing direction changes.

  Next, the optical path of the light when the LED unit 3 is caused to emit light will be described with reference to FIGS. In addition, since the light guide plate 2 has a symmetrical shape with respect to the first virtual surface, an optical path of light sent to the light guide unit 11 side will be described below. However, the optical path shown below is an example, and the present invention is not limited to this. Moreover, one plane formed by the surface 11a of the light guide unit 11 and the surface 12a of the light guide unit 12 is referred to as an irradiation side plane.

  First, the entire flow until the light emitted from the LED unit 3 becomes light irradiated from the irradiation side plane will be described.

  As shown in FIG. 3, light emitted from the LED unit 3 at a predetermined angle (φ) with respect to the first virtual plane (hereinafter referred to as excitation light) is reflected by the surface 13 a of the bent portion 13 and the phosphor 15. The wavelength is converted by, and fluorescence is generated in all directions. The fluorescence may be emitted to the outside as it is depending on the generation direction, or may be reflected by the surface 13 a of the bent portion 13 and emitted to the outside through the phosphor 15. The reflection at the bent portion 13 will be described later in detail. There is also light that is not converted into fluorescence but is reflected by the surface 13a of the bent portion 13 and is emitted to the outside as excitation light. Therefore, white light in which fluorescence and excitation light are mixed is emitted to the light guide unit 11.

  By the above, light (predetermined light) radiated from the surface 13a of the bent portion 13 in the direction (predetermined direction) of the surfaces 11c to 11e of the light guide portion 11 passes through the surfaces 11c to 11e of the light guide portion 11. And enters the light guide 11. In this case, light incident is refracted by the surface 11c-11e.

  Then, the light is guided while repeating total reflection along the surface 11 a inside the light guide unit 11. Specifically, the light incident on the light guide unit 11 is totally reflected in the non-scattering regions (that is, boundary surfaces) of the surface 11 a and the surface 11 b and travels in the light guide unit 11. Further, of the incident light, the light irradiated on the scattering portion of the surface 11b is scattered by the scattering portion. Of the scattered light, light that does not undergo total reflection at the surface 11a is emitted from the surface 11a. This becomes light irradiated from the irradiation side plane, and is irradiated to the side irradiated as white light.

  Further, even in the light that is repeatedly reflected and guided to the end portion (that is, the surface 11f) of the light guide unit 11, the light is not emitted to the outside because a scattering portion is formed on the surface 11f. The light is reflected or scattered at least on the light guide unit 11 side. Therefore, it is possible to utilize efficiently light incident from the outside.

  Of the light emitted from the LED unit 3, there is also light that directly enters the light guide unit 11 from the surface 11 c without being reflected by the surface 13 a of the bent portion 13.

  Then, the reflection at the bent portion 13, with reference to FIG. 2, will be described in detail.

  On the surface 13 a of the bent portion 13, as shown in FIG. 2, the excitation light emitted from the LED portion 3 is reflected by the surface of the phosphor 15 and light that is absorbed inside the phosphor 15 and becomes fluorescent. , And the light transmitted through the phosphor 15 and reflected by the surface 13a. The light reflected from the surface of the phosphor 15 is incident on the light guide unit 11 as the excitation light.

  On the other hand, the excitation light that has passed through the phosphor 15 is reflected by the surface 13 a, and again passes through the phosphor 15 and is emitted to the outside. However, while being transmitted through the phosphor 15, it is absorbed by the phosphor 15. By converting the wavelength of light, fluorescent light is generated.

  In addition, the excitation light that has entered the phosphor 15 and the converted fluorescence also become light in all directions due to scattering. Since the light emitted in the direction of the surface 13a is reflected, both the excitation light and the fluorescence are reflected by the surface 13a, and the mixed light is visibly white and emitted from the phosphor 15.

  In general, since the fluorescence has a smaller absorption coefficient in the phosphor 15 than the excitation light, the surface 13a under the phosphor 15 is made of a material that can reflect light, so that the lower direction of the phosphor 15 It is possible that the fluorescent light directed toward the surface is reflected by the surface 13a and emerges from the surface of the phosphor 15. Therefore, the light emitted from the phosphor 15 can be increased.

  Moreover, in the above, the surface 13a * 13b of the bending part 13 was comprised with the material which reflects light. However, if a part of the surfaces 13a and 13b is made of a material that transmits light, and the inside of the bent portion 13 and the inner surface 13c are made of a member that transmits light similar to the light guide portion 11 or the like, It is also possible to emit light from the LED unit 3 directly from the surfaces 13a and 13b of the bent portion 13. In this case, it becomes possible to irradiate the irradiation side with more uniform light from the light guide plate 2.

  As described above, in the light guide plate 2, the bent portion 13 causes the light emitted from the LED portion 3 to bend toward the surfaces 11 c to 11 e of the light guide portion 11 and enter the light guide portion 11. The light incident on the light guide unit 11 is emitted from the surface 11a to the irradiation side while being guided along the surface 11a. Therefore, the light guide plate 2 itself can be thinned.

  Moreover, in the light guide part 11, in order to guide the light inject | emitted from the LED part 3 along the surface 11a, the LED part 3 which emits external light is made close to the surface opposite to the surface 13a * 13b of the light-guide plate 2. It becomes possible to install. Furthermore, since it is not necessary to install the LED unit 3 at the edge part of the light guide plate 2, the surfaces 11a and 12a (that is, the irradiation side plane) can be easily formed in a matrix form as compared with the configuration of the conventional edge type backlight. It becomes possible to combine. For this reason, it becomes possible to easily enlarge the light emitting surface.

  Further, since the bent portion 13 is surrounded by the light guide portions 11 and 12, and the reflected light is emitted in all directions by the phosphor 15, more light is emitted from the LED portion 3 without unevenness, that is, efficiency. It becomes possible to send to the light guide parts 11 and 12 well. For this reason, uniform light emission can be obtained.

  Further, the bent portion 13 fluoresces the surfaces 13a and 13b on which external light is incident so that at least some of the wavelengths of the light irradiated on the surfaces 13a and 13b are converted into light of other wavelengths. Since the body 15 is applied, fluorescence, which is light whose wavelength has been converted, and excitation light, which is not converted, are emitted in all directions, so that the light is mixed and emitted as white light. Will be.

  Therefore, it becomes possible to take out white light by mixing light, and the bent portion 13 is surrounded by the light guide portions 11 and 12, so that the external light is more evenly, that is, the light guide portion is more efficient. 11 can be used. For this reason, uniform light emission can be obtained, and uniform white light can be irradiated to the irradiation side.

  As described above, the light guide plate 2 of the present embodiment can make the light emitting surface uniform and increase the size of the light emitting surface, and can efficiently extract and use white light.

  In addition, the lighting device 1 including the light guide plate 2 can be used as an indoor lighting device that emits light uniformly, and can also be suitably used as a large outdoor lighting device.

  Here, with reference to FIG. 5, the light intensity, that is, the light intensity due to the mixture of the fluorescence reflected from the bent portion 13 and the excitation light is changed by changing the coating film thickness of the phosphor 15. explain. FIG. 5 is a graph showing the calculation results of the coating film thickness and the light intensity of the phosphor 15, the vertical axis represents the light intensity, and the horizontal axis represents the coating film thickness (t). Curves A to C show the coating film thickness dependence of the fluorescent light intensity in the reflective structure, and curves D and E show the dependence of excitation light attenuation on the coating film thickness when the excitation light passes through the phosphor 15. Showing gender.

  Curve A shows the case where the absorption coefficient of the external incident light by the phosphor 15 (hereinafter referred to as excitation light absorption coefficient) is 500 / cm, and the absorption coefficient by the fluorescent material of phosphor 15 (hereinafter referred to as fluorescence absorption coefficient) is 100 / cm. The curve B shows a case where the excitation light absorption coefficient is 500 / cm and the fluorescence absorption coefficient is 50 / cm, and the curve C shows an excitation light absorption coefficient of 100 / cm and a fluorescence absorption coefficient of 50. The case of / cm is shown. Curves D and E show cases where the excitation light absorption coefficients are 500 / cm and 100 / cm, respectively.

  Referring to the graph of FIG. 5, when the fluorescence is extracted from the incident side of the excitation light, the fluorescence emitted from the surfaces 13a and 13b can be obtained if the excitation light reaches a thickness of the phosphor that does not reach the surfaces 13a and 13b. Since the light intensity is constant, the light intensity does not depend on the coating thickness of the phosphor. Therefore, in the above case, if the coating thickness of the phosphor is more than a certain value, it is not necessary to control the coating thickness of the phosphor.

  Conversely, when the phosphor coating thickness is controlled so that the excitation light is reflected by the surfaces 13a and 13b and reaches the phosphor 15 surface, the excitation light The coating thickness of the phosphor 15 is determined by the mixing ratio with the fluorescence. In order to increase the fluorescence color, the coating film thickness of the phosphor 15 may be increased. In order to increase the excitation light color, the coating film thickness of the phosphor 15 may be decreased.

  For example, when controlling the color using the excitation light so as to generate a pseudo white color by combining the excitation light of the blue LED and the yellow phosphor 15, it is necessary to control the amount of excitation light emitted from the phosphor 15. There is. Therefore, by adjusting the phosphor film thickness to a thickness that converts the desired amount of light irradiated to the surfaces 13a and 13b into fluorescence, the mixing ratio of fluorescence and excitation light is controlled, and white light is controlled. Can be generated. The light intensity of the fluorescence needs to be determined depending on the individual material due to the influence of the conversion efficiency.

  As described above, the light intensity generated from the bent portion 13 can be controlled by adjusting the coating film thickness of the phosphor 15. In addition, desired light intensity and color can be obtained.

  Moreover, if the application area of the fluorescent substance 15 is changed, the light intensity reflected from the bending part 13 will change. Thereby, the ratio of excitation light is increased / decreased by the increase / decrease in the application area of the fluorescent substance 15.

  For example, when controlling the color using the excitation light so as to generate a pseudo white color by combining the excitation light of the blue LED and the yellow phosphor 15, it is necessary to control the amount of excitation light emitted from the phosphor 15. There is. Therefore, by adjusting the phosphor area to the area where the desired amount of light irradiated to the surfaces 13a and 13b is converted into fluorescence, the mixing ratio of fluorescence and excitation light is controlled, and white light is controlled. Can be generated.

  However, in order to mix both lights into a specific color light (for example, white), it is determined by the reflectance of the phosphor surface of the excitation light, the conversion efficiency at the phosphor, the spectrum of both wavelengths, and the like.

  As described above, the light intensity generated from the bent portion 13 can be controlled by controlling the application area of the phosphor 15. In addition, desired light intensity and color can be obtained.

  Further, as shown in FIG. 6, the light guide plate 2 may include a reflection plate 21 a inside the light guide portion 11 and a reflection plate 22 a inside the light guide portion 12. FIG. 6 is a perspective view showing a configuration of the light guide plate 20 including the reflection plate 21a and the reflection plate 22a. Hereinafter, the light guide unit 11 will be described, but the light guide unit 12 has the same configuration.

  The reflection plate 21a is arranged perpendicular to the surface 11a. Further, the reflecting plate 21a has a shape that is the same as a bent shape with respect to a line (center line) that is a line parallel to the one side of a rectangle having a side length d and that passes through the center of the rectangle. Yes. Further, the reflecting plate 21a is symmetrical with respect to a plane perpendicular to the surface 11a, that is, a plane that bisects the light guide portion 11 through the intersection line of the surface 11g and the surface 11h.

  According to said structure, the light which injected into the light guide part 11 is reflected also in the reflecting plate 21a. Therefore, it is possible to control the amount of light in the surface by increasing the amount of light in the reflected direction, and to uniformly control the amount of light in the surface. In addition, the number of the reflecting plates 21a is not limited to one, and can be increased or decreased as necessary.

  Moreover, in the said light-guide plate 2, the surface 13a * 13b of the bending part 13 may incline in a mutually different direction at the same angle ((theta)) with respect to a 1st virtual surface. Thereby, it is possible to make the amount of light reflected by the surface 13a and the surface 13b the same by irradiating external light from a certain position on the first virtual plane in the direction of the irradiation side plane. Therefore, the same amount of light can be incident on the light guide unit 11 and the light guide unit 12.

  In the light guide plate 2, the surface 11c of the light guide 11 and the surface 12c of the light guide 12 are configured to be perpendicular to the surface 11a and the surface 12a. However, the present invention is not limited to this. For example, the surface 11c is inclined with respect to the first virtual plane in a direction in which light bent (reflected) by the surface 13a is refracted in the direction of the surface 11a, and the surface 12c May be inclined with respect to the first imaginary plane in a direction in which light bent (reflected) by the surface 13b is refracted in the direction of the surface 12a.

  Further, in the light guide plate 2, the light from the LED part 3 is reflected (bent) using the two surfaces 13 a and 13 b of the bent part 13, but the present invention is not limited to this. For example, if it is the structure which reflects the light from 3 parts of LED parts, it may be a curved surface like the surface except the bottom face of the cone, or it may be four faces except the bottom face of the quadrangular pyramid. Also good.

  The light guide plate 2 has a configuration in which the light guide portion 11 and the light guide portion 12 are symmetrical with each other. Thereby, compared with the case where the light guide part 11 and the light guide part 12 are asymmetrical shapes, the structure of the light guide plate 2 can be simplified.

  On the other hand, in the light guide plate 2, the light guide unit 11 and the light guide unit 12 have been described as being symmetrical with each other, that is, the same shape, but is not limited thereto. Even if the areas of the surface 11a of the light guide 11 and the surface 12a of the light guide 12 are different, by changing the pattern of the surface 11b and the surface 12b, per unit area emitted from the surface 11a and the surface 12a. It is also possible to have the same amount of light.

  Therefore, even in the above case, that is, in the case of asymmetry, it is possible to irradiate the indoor side with uniform light. In addition, even if the position of the LED unit 3 is limited by changing the size ratio between the light guide unit 11 and the light guide unit 12, uniform light can be emitted from the surfaces 11a and 12a. Is possible.

  Further, in the light guide plate 2, if the reflection sheet is placed so as to face the surface 11b and the surface 12b, it is possible to increase the amount of light emitted from the surface 11a and the surface 12a. .

  Moreover, although LED was used as a point light source in the said embodiment, it is not limited to this, You may utilize light sources other than LED, for example, a semiconductor laser. Further, instead of the point light source, a line light source may be arranged along the intersection line. As a result, a general-purpose light source can be used as a light source that emits external light without requiring a special light source, so that an illumination device can be obtained at low cost.

  Furthermore, in order to realize as bright illumination as possible, it is necessary to increase the luminance of the light emitting element. Therefore, in the LED unit 3, since it is necessary to use a watt-class (for example, 2W) high-power LED chip, a light-emitting element having a package with good heat dissipation is required. As an example of this light emitting element, for example, the structure described in Patent Document 4 can be cited. In the above structure, the heat radiator on which the LED chip is directly mounted may be a metal or a ceramic such as AlN, and is preferably used.

  Moreover, although the illuminating device 1 of this Embodiment was demonstrated as a normally used indoor or outdoor illuminating device, for example, a fluorescent lamp etc., it is not restricted to this, The liquid crystal panel of a liquid crystal display device is irradiated from a back surface It can be suitably used as a backlight.

  The present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the claims, and the technical means disclosed in different embodiments can be appropriately combined. Such embodiments are also included in the technical scope of the present invention.

  The present invention can be suitably applied to indoor and outdoor lighting devices such as fluorescent lamps. Moreover, it can be suitably used as a backlight for irradiating the liquid crystal panel of the liquid crystal display device from the back side.

Is a perspective view showing an embodiment of the lighting device of this embodiment. Is an enlarged sectional view showing the configuration of the bent portion of the light guide plate in the lighting device. It is an AA cross-sectional view taken along line of a light guide plate of the illumination device shown in FIG. It is the figure which showed arrangement | positioning of LED in the said illuminating device. It is a graph which shows the calculation result of a fluorescent substance coating film thickness and light intensity. It is a perspective view which shows the other structure of the light-guide plate in the said illuminating device. It is a graph which shows the calculation result of fluorescent substance film thickness and fluorescence intensity. It is a sectional view showing a structure of a liquid crystal display device provided with a conventional edge-type backlight. It is the perspective view which expanded and showed a part of pattern of the spreading | diffusion part on the acrylic board in the said liquid crystal display device. It is sectional drawing which shows the structure at the time of arranging the conventional edge type | mold backlight in parallel.

DESCRIPTION OF SYMBOLS 1 Illuminating device 2 Light guide plate 3 LED part (light emitting element)
11 light guide 11a surface (light exit surface)
12 light guide part 12a surface (light emission surface)
13 Bent part (light input part)
13a Surface (reflection surface)
13b Surface (reflection surface)
15 Phosphor 20 Light guide plate 21a Reflector 22a Reflector

Claims (6)

In a light guide plate including a light guide unit that emits light from a light emitting surface to the outside while guiding predetermined light incident from a predetermined direction along the light emitting surface.
A light input unit that bends external light incident from the opposite side of the light exit surface in the predetermined direction and enters the light guide unit;
The light input unit converts the wavelength of at least a part of the light irradiated on the reflecting surface to the reflecting surface on which the external light is incident, and converts some of the light to other wavelengths. A phosphor film to be transmitted is applied ,
Of the light irradiated to the reflecting surface, light of a desired color is generated by color mixing of light whose wavelength is converted and light whose wavelength is not converted, and the light of the desired color is guided from the light input unit. A light guide plate, wherein a coating thickness of the phosphor film is adjusted so as to be incident in an optical part . In a light guide plate including a light guide unit that emits light from a light emitting surface to the outside while guiding predetermined light incident from a predetermined direction along the light emitting surface.
A light input unit that bends external light incident from the opposite side of the light exit surface in the predetermined direction and enters the light guide unit;
The light input unit converts the wavelength of at least a part of the light irradiated on the reflecting surface to the reflecting surface on which the external light is incident, and converts some of the light to other wavelengths. A phosphor film to be transmitted is applied ,
Of the light irradiated to the reflecting surface, light of a desired color is generated by color mixing of light whose wavelength is converted and light whose wavelength is not converted, and the light of the desired color is guided from the light input unit. A light guide plate, wherein a coating area of the phosphor film is adjusted so as to be incident in an optical part . The reflective surface may include a light guide plate according to claim 1 or 2, characterized in that transmits part of the light irradiated to the reflecting surface. The light guide plate according to any one of claims 1 to 3 ,
A light emitting element that emits external light,
The illuminating device according to claim 1, wherein the light emitting element is disposed at a position where a light emitting surface is opposed to a side that is not a light emitting surface of the reflecting surface of the light input unit. 5. The illumination device according to claim 4 , wherein the external light is light emitted from a light emitting diode. 5. The illumination device according to claim 4 , wherein the external light is light emitted from a semiconductor laser.

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