JP2008130422A - Lighting system and liquid crystal display device provided with same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting system capable of improving a dynamic range of an image without using a partition wall for isolating an illumination region the same as a case that the partition wall is used, and provide a liquid crystal display device provided with the same. <P>SOLUTION: A backlight 20 as the lighting system is provided with a point light source 23 including a white LED 21 and a lens 22, a comparison diffusion member 25 with an illumination region 25a corresponding to the point light source 23. A surface of the lens 22 has a minimum curvature radius at a part where a boundary axis I, which links a center of the point light source 23 and an end of the illumination region 25a, passes, and has a shape in which the curvature radius increases as close to an optical axis L side from this part. Radiation intensity of emitted light of the white LED 21 is changed at the lens 22, and radiation strength distribution having a peak in a direction of an angle θm can be obtained. Radiated light of uniform illuminance is obtained in the illumination region 25a and leakage of illuminated light to the adjacent illumination region 25a can be prevented without using a conventional partition wall. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an illumination device suitable for a so-called backlight that illuminates, for example, a transmissive liquid crystal panel from the back side.

  A liquid crystal display device has features such as thinness, low power consumption, and high definition, and a screen size is increasing due to development of manufacturing technology. Therefore, a liquid crystal display device is replaced with a conventional CRT (cathode ray tube) instead of a conventional television. John's application is progressing.

  However, the image displayed on the liquid crystal display device has a problem that the dynamic range is lower than that of the CRT image due to the display method. In order to solve this problem, the liquid crystal panel is divided into a plurality of display areas, a plurality of illumination areas corresponding to the display areas are formed in the backlight, and brightness control of the illumination areas of the backlight is performed independently. There is a liquid crystal display device. In this liquid crystal display device, the luminance of illumination light in each illumination area of the backlight is controlled in accordance with the brightness of an image displayed on the display area of the liquid crystal panel. That is, the illumination area corresponding to the display area displaying the bright image increases the brightness of the illumination light, while the illumination area corresponding to the display area displaying the dark image decreases the brightness of the illumination light. Thereby, the dynamic range of the image is expanded to improve the contrast feeling.

Conventionally, such a backlight having a plurality of illumination areas is as shown in FIG. 15 (see, for example, JP-A-2002-99250). This backlight is a direct type backlight used so that the light source is located directly under the liquid crystal panel. The backlight includes a plurality of light sources 501 and divides the light from each light source 501 by a partition wall 502 to form an illumination area. is doing. The light source 501 is composed of a plurality of cold cathode fluorescent tubes arranged parallel to each other so as to penetrate the partition wall 502, and an LED (light emitting diode) (not shown) arranged for each illumination region below the cold cathode fluorescent tube. ing. While always lighting the said fluorescent tube, the brightness | luminance of said LED is controlled for every illumination area, and the dynamic range of the image displayed on the display area of a liquid crystal panel is expanded. Further, by separating each illumination area by the partition wall 502, interference of illumination light between adjacent illumination areas is prevented, and a high-quality image is obtained.
JP 2002-99250 A

  However, the conventional backlight has the following problems. That is, it takes time to manufacture the partition wall 502 that isolates the illumination area. Also, it takes time to assemble the fluorescent tube so as to penetrate the partition wall 502. Further, since the LED has low directivity, there is a disadvantage that light leaks easily to the adjacent illumination area through the gap between the partition wall and the liquid crystal panel.

  SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an illuminating device that can improve the dynamic range of an image as in the case of using a partition without using a partition that separates the illumination area, and a liquid crystal display device including the same. is there.

  In order to solve the above problems, an illumination device of the present invention includes a plurality of point light sources and a light diffusion member that diffuses light from the point light sources, and the light diffusion member includes the plurality of point light sources. In the illumination device having a plurality of illumination areas formed corresponding to the point light source, a line connecting the center of the point light source and an end of the illumination area corresponding to the point light source is the light. When the angle formed with respect to the axis is θm, the absolute value has a maximum value of radiation intensity in the direction of angle θ satisfying 0 <θ ≦ θm.

  According to the present invention, in the illumination device configured as described above, the point light source includes a light emitting diode and a lens that changes a radiation intensity distribution of light emitted from the light emitting diode.

  According to the present invention, in the illumination device configured as described above, the surface on the light emission side of the lens has a shape that changes a radiation intensity distribution of the emission light of the light emitting diode.

  According to the present invention, in the illumination device having the above-described configuration, the lens has a shape in which a radius of curvature increases as the surface on the light exit side increases from the position at an angle of θm to the optical axis toward the optical axis. It is characterized by being.

  According to the present invention, in the illumination device having the above-described configuration, a light-shielding member disposed around the point light source is provided.

  In the illumination device having the above-described configuration, the light-shielding member blocks light having an angle greater than θm with respect to the optical axis, out of light emitted from the point light source.

  Further, in the illumination device having the above-described configuration, the present invention is configured such that light emitted from a point light source other than the point light source corresponding to each illumination region is not substantially incident on the plurality of illumination regions of the light diffusion member. Features.

  According to the present invention, in the illumination device configured as described above, the plurality of point light sources is controlled in luminance of emitted light.

  According to another aspect of the present invention, there is provided a liquid crystal display device including the illumination device having the above-described configuration and a liquid crystal panel disposed on a light emission side of the illumination device.

  According to the first configuration of the present invention, the light emitted from the point light source enters the illumination area corresponding to the point light source of the light diffusing member, is diffused in the illumination area, and is substantially uniform. Light is obtained. Moreover, since the point light source has the maximum radiation intensity at an angle θ satisfying an absolute value of 0 <θ ≦ θm, the illuminance of the illumination area corresponding to the point light source can be made higher than that of the adjacent illumination area. Therefore, when this lighting device is used for a liquid crystal panel, the dynamic range of an image displayed on the liquid crystal panel can be improved without providing a partition that separates a plurality of lighting regions from each other.

  The lighting device of the present invention is not limited to a liquid crystal panel, and can be used for a panel of another display device such as an electrophoretic display panel.

  According to the second configuration of the present invention, by changing the radiation intensity distribution of the emitted light of the light emitting diode with the lens, the illuminance in the corresponding illumination region can be effectively increased with a simple configuration. That is, since the directivity of a relatively low light emitting diode can be enhanced by the lens, light leakage to the adjacent illumination region can be reduced as compared with the conventional case.

  According to the third configuration of the present invention, a lens capable of obtaining a predetermined radiation intensity distribution can be easily manufactured.

  According to the 4th structure of this invention, the light from a light emitting diode can be irradiated with a uniform and high illumination intensity in a corresponding illumination area.

  According to the fifth configuration of the present invention, it is possible to effectively prevent leakage of irradiation light to the outside of the illumination area corresponding to the point light source.

  According to the sixth configuration of the present invention, it is possible to reliably prevent leakage of irradiation light to the outside of the illumination area corresponding to the point light source.

  According to the 7th structure of this invention, the leak of the light to an adjacent illumination area can be prevented reliably.

  According to the eighth configuration of the present invention, when the illumination device is used for a liquid crystal panel, the luminance of the emitted light of the plurality of point light sources is controlled according to an image displayed on the liquid crystal panel, thereby The dynamic range of the image displayed on the liquid crystal panel can be improved.

  According to the ninth configuration of the present invention, a liquid crystal display that can improve the contrast of an image displayed on the liquid crystal panel easily and inexpensively by providing an illumination device that can prevent leakage of irradiation light between illumination areas without using a partition wall. A device is obtained.

  Hereinafter, an illumination device according to an embodiment of the present invention will be described in detail with reference to the drawings.

(First embodiment)
Fig.1 (a) is a top view which shows typically the backlight 20 as an illuminating device of 1st Embodiment. FIG. 1B is a schematic cross-sectional view of the backlight 20, and FIG. 1C is a schematic plan view of a white LED (light emitting diode) 21 that is a constituent member of a point light source. The backlight 20 includes a plurality of point light sources 23, and the point light source 23 includes a white LED 21 and a lens 22 disposed on the white LED 21. The white LED 21 is formed by three elements of a red LED 21R, a green LED 21G, and a blue LED 21B having different emission wavelengths. A light diffusing member 25 that diffuses light from the point light source 23 is disposed above the point light source 23. A reflection sheet 24 is provided on the inner surface of the casing that houses the point light source 23. The reflection sheet 24 is formed by a side sheet 24 a disposed on the side of the point light source 23 and a bottom sheet 24 b disposed on the mounting surface side of the white LED 21 of the point light source 23.

  The plurality of point light sources 23 are arranged in a matrix direction at a pitch of 28 mm on the bottom surface of the casing. No partition wall is provided between the casing and the light diffusion member 25 to separate the illumination areas from each other.

  The light diffusing member 25 uses CLAREX (trade name) DR-IIIC DR-60C manufactured by Nitto Jushi Kogyo Co., Ltd., and has a thickness of 2.0 (mm) and a haze ratio of 96 (%). Is used. The light diffusing member 25 has a transmittance of 93% and an absorptance of 7%. The reflectance of light at an incident angle of 0 ° is 3.3%, the reflectance of light at an incident angle of 20 ° is 3.2%, and the reflectance of light at an incident angle of 40 ° is 3.8%. The reflectance of light with an incident angle of 60 ° is 11.0%. The light diffusing member 25 is arranged so that the lower surface is located at a height of h = 20 (mm) from the mounting surface of the point light source 23. A plurality of illumination areas 25 a, 25 a,... Are formed in the light diffusion member 25 corresponding to the plurality of point light sources 23. The illumination areas 25a, 25a,... Of the light diffusing member 25 are virtually defined by boundary lines 25b, 25b,.

  FIG. 2A is a schematic cross-sectional view of the point light source 23, and FIG. 2B is a schematic plan view of the point light source 23. FIG. 3 is a schematic cross-sectional view for explaining the positional relationship between the point light source 23 and the light diffusing member 25. The lens 22 of the point light source 23 can be formed using a transparent resin material such as PMMA (polymethyl methacrylate), PC (polycarbonate) and EP (epoxy resin), or transparent glass.

  As will be described below, the lens 22 has a shape for changing the radiation intensity distribution of light from the white LED 21 to a predetermined distribution. In FIG. 3, L is the optical axis that faces the normal direction of the light emitting surface of the white LED 21. Also, let I be the axis (hereinafter referred to as the boundary axis) from the center of the point light source 23 toward the end of the illumination region 25a of the light diffusion member 25, that is, the virtually drawn boundary line 25b. In addition, the center of the point light source 23 means a point where the center of gravity of the light emitting region in the plan view of the white LED 21 is lowered to the lower side which is the mounting surface. The boundary axis I passes through the boundary line 25b on the lower surface of the diffusing member 25. If the angle between the optical axis L and the boundary axis I is θm (°), the width H (mm) of the illumination area and the distance h (mm) from the mounting surface of the white LED 21 to the lower surface of the light diffusion member 25 The value of θm is determined by. For example, when H = 28 mm and h = 20 mm, θm is about 35 °.

  The surface of the lens 22 is generally composed of an optical axis portion 22a through which the optical axis L passes and a side portion 22b that faces in a direction substantially perpendicular to the optical axis. The shape of the optical axis portion 22a on the surface of the lens 22 is a curve with a radius of curvature of 2 mm in a section passing through the optical axis in the direction of the angle θm from the center of the point light source 23, that is, the portion through which the boundary axis I passes. To do. The portion closer to the optical axis L than the portion through which the boundary axis I passes is formed in a gentle curved shape so that the radius of curvature increases toward the optical axis L. This gentle curve is connected at the point where the optical axis L passes. On the other hand, the side portion 22b of the surface of the lens 22 is formed as follows by setting an axis I 'extending in a direction perpendicular to the optical axis L from the center of the point light source 23. That is, in a curve having a radius of curvature of 2 mm drawn from the center of the point light source 23 in the direction of the angle θm, a line extending from the point where the axis I ′ direction coordinate is maximum to the axis I ′ in the direction parallel to the optical axis L. To set the cross-sectional shape of the side portion 22b.

  The point light source 23 having the lens 22 having the surface shape set as described above can obtain angular characteristics as shown in FIG. In FIG. 4, the horizontal axis is an angle representing the direction from the center of the point light source 23, and the vertical axis is the normalized radiation intensity. 0 ° on the horizontal axis indicates the direction of the optical axis L. As shown in FIG. 4, the point light source 23 having this lens 22 has a peak of radiation intensity in the direction of the angle θm, and the radiation intensity increases toward 0 ° at an angle θ whose absolute value is smaller than the angle θm. Is reduced.

  By using the point light source 23 having such a radiation intensity distribution, an illuminance distribution as shown in FIG. 5 is obtained in the illumination region 25a of the light diffusion member 25. In FIG. 5, the horizontal axis is the distance in the direction perpendicular to the optical axis L from the center of the point light source 23, and the vertical axis is the normalized intensity normalized by the maximum value. On the horizontal axis of FIG. 5, the width between −H / 2 and H / 2 corresponds to the width of the illumination area 25a. In FIG. 5, in addition to the illuminance distribution of the present embodiment, the illuminance distribution when the light diffusing member 25 is irradiated by the point light source of the first comparative example using only LEDs is shown superimposed. In FIG. 5, while the illuminance distribution of the point light source 23 of the present embodiment is indicated by a solid line, the illuminance distribution of the point light source of the first comparative example is indicated by a broken line. As can be seen from FIG. 5, by using the point light source 23 having the lens 22 of the present embodiment, illumination light having a substantially uniform illuminance can be obtained in the illumination area 25 a corresponding to the point light source 23.

  FIGS. 6A and 6B are schematic cross sections showing the shape of each lens and the result of ray tracing in each lens for the point light source 23 of the present embodiment and the point light source 123 of the second comparative example. FIG. FIG. 6A is a diagram showing the point light source 23 of the present embodiment, and FIG. 6B is a diagram showing the point light source 123 of the second comparative example. The point light source 23 of the present embodiment and the point light source 123 of the second comparative example include the same white LED 21, but the surface shapes of the lenses 22 and 122 are different from each other. In the point light source 23 of this embodiment, the surface of the lens 22 has a small radius of curvature at the angle θm in the cross section passing through the optical axis, and the radius of curvature at the optical axis side is larger than the angle θm. It is formed into a shape. On the other hand, in the point light source 123 of the second comparative example, the surface of the lens 122 is formed in a spherical shape having a substantially single curvature radius.

  In the lens 22 included in the point light source 23 of the present embodiment, as shown in FIG. 6A, the light ray path that passes through the portion smaller than the angle θm with respect to the optical axis passes through the portion larger than the angle θm. It becomes denser than the light beam path, and a predetermined directivity is obtained. On the other hand, in the lens 122 included in the point light source 123 of the second comparative example, as shown in FIG. 6B, the light path is almost uniform at any angle with respect to the optical axis, and there is almost no directivity. .

  FIGS. 7A and 7B are diagrams for explaining the characteristics of the point light source 23 of the present embodiment. FIGS. 8A and 8B show the point light source 123 of the second comparative example. It is a figure explaining the characteristic which has. In FIG. 7A and FIG. 8A, the horizontal axis is the angle from the center of the point light source, and the vertical axis is the normalized radiation intensity. 7B and 8B, the horizontal axis is the distance from the center of the point light source, and the vertical axis is the normalized illuminance. As shown in FIG. 7A, the point light source 23 of the present embodiment has a peak of radiation intensity in a direction of 35 ° with respect to the optical axis, and as a result, as shown in FIG. 7B. Illumination light with substantially uniform illuminance is obtained within a range corresponding to the illumination region 25a.

  On the other hand, as shown in FIG. 8A, the point light source 123 of the comparative example has a radiation intensity distribution in which the radiation intensity decreases as the angle from the optical axis increases with the optical axis direction as a peak. . As a result, as shown in FIG. 8B, an illuminance peak is formed at the central portion through which the optical axis passes, and the illuminance is significantly reduced at a position corresponding to the end of the illumination area. As described above, according to the present embodiment, by using the lens 22 having a predetermined surface shape, the characteristics of light from the white LED 21 are changed, and illumination light with uniform illuminance is obtained in the illumination area 25a. be able to.

  FIG. 9 is a diagram showing a point light source 223 of the third comparative example. The point light source 223 has a strong directivity compared to the point light source 123 of the second comparative example because the lens 222 has an aspherical surface, but the illuminance is different from that of the point light source 23 of the present embodiment. Have a distribution. As shown in FIG. 9, the surface of the lens 222 of the point light source 223 of the third comparative example has a concave cross section in which a portion near the optical axis is recessed toward the white LED 221 than a portion around the optical axis. As a result, as shown by a curve A in FIG. 10, an illuminance distribution is obtained in which the illuminance is substantially uniform in the vicinity of the optical axis, but the illuminance is relatively large even outside the range where the illuminance is substantially uniform.

  This is because the surface of the lens 222 of the third comparative example has a shape that emits emitted light to the side of the white LED 221 as well. In FIG. 10, the illuminance distribution by the point light source provided with the hemispherical lens is shown by being overlapped with a curved line B by a broken line. In FIG. 10, the horizontal axis represents the distance from the optical axis, and the vertical axis represents the amount of emitted light. Further, H ′ in FIG. 10 is the width of the illumination area to be irradiated by one point light source 123.

  FIG. 10 also shows a curve C representing the amount of light when the point light sources 223 of the third comparative example are arranged at predetermined intervals and all the light sources are turned on. In addition, a curved line D representing the amount of light when the point light sources provided with hemispherical lenses are arranged at predetermined intervals and all the light sources are turned on is shown superimposed. As shown by the curve C in FIG. 10, when the adjacent point light sources 223 of the third comparative example are turned on, a substantially uniform amount of light can be obtained between the adjacent illumination areas. There is a leakage of illumination light between the matching illumination areas. Therefore, when the illumination device is configured using the point light source 223 of the third comparative example, the contrast of the display image is not sufficiently improved.

  On the other hand, as shown in FIG. 7B, the point light source 23 of the present embodiment can obtain illumination light with substantially uniform illuminance within a range corresponding to the illumination area 25a, and the illumination area 25a. Since the illuminance outside can be significantly reduced, it is possible to effectively prevent the illumination light from leaking between the adjacent illumination regions 25a.

  The liquid crystal display device configured using the backlight 20 of the present embodiment can effectively expand the dynamic range of images displayed on the liquid crystal panel. Specifically, a liquid crystal display device is configured by disposing a transmissive liquid crystal panel on the light emitting side of the light diffusion member 25 of the backlight 20 of the present embodiment. The liquid crystal display device includes a luminance control circuit that controls the luminance of the point light source 23 of the backlight 20 based on an image displayed on the liquid crystal panel. With this luminance control circuit, the luminance of the corresponding point light source 23 is controlled to be high for the illumination region corresponding to the display region for displaying a bright image on the liquid crystal panel. On the other hand, the brightness of the corresponding point light source 23 is controlled to be low in the illumination area corresponding to the display area where the dark image on the liquid crystal panel is displayed.

  Thereby, the dynamic range of the image displayed on the liquid crystal panel can be expanded. Further, the backlight 20 according to the present embodiment does not require a partition wall that separates the illumination areas as in the prior art, and thus has a simple structure, is easy to assemble, and can be manufactured at low cost. Therefore, the contrast of the image of the liquid crystal display device can be improved easily and inexpensively as in the conventional case. Further, since the backlight 20 of the present embodiment uses only the white LED 21 as a light source, the emission spectrum of the cold cathode fluorescent tube and the LED as in the conventional backlight using the cold cathode fluorescent tube and the LED as the light source is as follows. There is no problem of color reproduction error caused by the difference.

  In the above embodiment, the lens 22 of the point light source 23 uses a transparent resin material added with a diffusing agent from the viewpoint of efficiently mixing the emitted light from the three LEDs of the red LED 21R, the green LED 21G, and the blue LED 21B. Is preferred. Thereby, the occurrence of color unevenness between the illumination areas can be more effectively prevented.

(Second Embodiment)
Fig.11 (a) is a top view which shows typically the backlight 80 as an illuminating device of 2nd Embodiment, FIG.11 (b) is a schematic cross section of the backlight 80 of this embodiment, FIG. 11C is a schematic plan view of the white LED 81 constituting the point light source 83. Similar to the first embodiment, the backlight 80 of the present embodiment includes a plurality of point light sources 83 arranged in the matrix direction, and the point light sources 83 are disposed on the white LEDs 81 and on the white LEDs 81. The formed lens 82 is included. The white LED 81 is formed by three elements of a red LED 81R, a green LED 81G, and a blue LED 81B.

  A light diffusing member 85 is disposed above the point light source 83, while a reflection sheet 84 is provided on the inner surface of the casing that houses the point light source 83. The reflection sheet 84 is formed of a side sheet 84 a on the side of the point light source 83 and a bottom sheet 84 b on the mounting surface side of the white LED 81. The point light source 83, the light diffusion member 85, and the reflection sheet 84 are the same as those in the first embodiment. On the other hand, this embodiment is different from the first embodiment in that a light shielding member 86 disposed around the point light source 83 is provided.

  The white LED 81 and the lens 82 of the point light source 83 have the same configuration as the white LED 21 and the lens 22 of the first embodiment. The point light sources 83 including the white LEDs 81 and the lenses 82 are arranged in a matrix direction at a pitch of 28 mm. The light diffusion member 85 is arranged at a height of h = 20 mm from the mounting surface of the point light source 83. A plurality of illumination areas 85 a, 85 a,... Are formed on the light diffusing member 85 corresponding to the plurality of point light sources 83. These illumination areas 85a, 85a,... Are virtually defined by boundary lines 85b, 85b,..., And the width H of the illumination area 85a is 28 mm.

  12A is a schematic sectional view of the point light source 83 and the light shielding member 86, and FIG. 12B is a schematic plan view of the point light source 83 and the light shielding member 86. As shown in FIGS. 12A and 12B, the backlight 80 of the present embodiment has a light shielding member 86 having a right triangular cross section around a point light source 83 having the same configuration as that of the first embodiment. In a square shape in plan view.

  The backlight 80 according to the present embodiment corresponds to the lens 82 of the point light source 83 having a surface shape similar to that of the first embodiment and a light shielding member 86 around the point light source 83. Leakage of illumination light to the outside of the illumination area 85a can be further effectively prevented. That is, the light shielding member 86 of the present embodiment effectively reduces the radiation intensity at an angle θ whose absolute value is larger than θm, as compared with the angle characteristics of the point light source 23 of the first embodiment shown in FIG. Can be reduced.

  FIG. 13 is a diagram showing angle characteristics of light obtained by the point light source 83 and the light shielding member 86 of the present embodiment. In FIG. 13, the horizontal axis is an angle representing the direction from the center of the point light source 83, and the vertical axis is the normalized radiation intensity. As shown in FIG. 13, the point light source 83 and the light shielding member 86 have a peak of the radiation intensity in the direction of the angle θm, and greatly reduce the radiation intensity at an angle θ having an absolute value larger than the angle θm. it can. With such a radiation intensity distribution, an illuminance distribution of illumination light as shown in FIG. 14 is obtained. As can be seen from FIG. 14, illumination light having a substantially uniform illuminance can be obtained within a range corresponding to the width H of the illumination area, while leakage of illumination light is effectively prevented outside the width H of the illumination area. it can.

  A liquid crystal panel is disposed opposite to the light emitting side of the backlight 80 of this embodiment, and a luminance control circuit for controlling the luminance of the point light source 23 of the backlight 80 is provided to constitute a liquid crystal display device. Since the backlight 80 can highly prevent leakage of illumination light to adjacent illumination areas, this liquid crystal display device can further expand the dynamic range of images displayed on the liquid crystal panel.

  In the present embodiment, the light shielding member 86 may be made of any material as long as it can block light in the direction of the angle θ having an absolute value larger than the angle θm, but in order to reduce loss due to light absorption. In addition, it is preferable to use a reflector material.

  Further, in the point light sources 23 and 83 of the backlights 20 and 80 of the above embodiments, the peak of the radiation intensity exists in the direction of the angle θm with respect to the optical axis L, but the absolute value is smaller than the angle θm. And you may have the peak of radiation intensity in the direction of angle theta larger than 0.

  In addition, the backlights 20 and 80 of the above embodiments are used for a liquid crystal panel to constitute a liquid crystal display device, but may be used for a panel of another display device such as an electrophoretic display panel.

FIG. 1A is a schematic plan view showing a backlight as the illumination device of the first embodiment, FIG. 1B is a schematic sectional view of the backlight, and FIG. 1C is a point light source. It is a schematic plan view which shows white LED which is a structural member. FIG. 2A is a schematic cross-sectional view of a point light source, and FIG. 2B is a schematic plan view of the point light source. It is a schematic cross section explaining the positional relationship between a point light source and a light diffusing member. It is a figure which shows the angle characteristic of a point light source. It is the figure which overlapped and showed the illuminance distribution by the point light source of 1st Embodiment, and the illuminance distribution by the point light source of a 1st comparative example. FIG. 6A is a schematic cross-sectional view showing a light tracking result in the point light source of the first embodiment, and FIG. 6B is a schematic cross-sectional view showing a light tracking result in the light source of the second comparative example. FIG. 7A is a diagram showing the angle characteristics of the point light source of the first embodiment, and FIG. 7B is a diagram showing the illuminance distribution by the point light source of the first embodiment. FIG. 8A is a diagram showing the angle characteristics of the point light source of the second comparative example, and FIG. 8B is a diagram showing the illuminance distribution by the point light source of the second comparative example. It is a figure which shows the point light source of a 3rd comparative example. It is the figure which piled up and showed the illuminance distribution of the point light source of the 3rd comparative example, and the illuminance distribution of the point light source which has a hemispherical lens. FIG. 11A is a schematic plan view showing a backlight as the illumination device of the second embodiment, FIG. 11B is a schematic cross-sectional view of the backlight, and FIG. 11C is a point light source. It is a schematic plan view which shows white LED which is a structural member. 12A is a schematic cross-sectional view of a point light source and a light shielding member, and FIG. 12B is a schematic plan view of the point light source and the light shielding member. It is a figure which shows the angle characteristic of the light obtained by a point light source and a light-shielding member. It is a figure which shows the illumination intensity distribution of the illumination light obtained by a point light source and a light-shielding member. It is a figure which shows the conventional backlight.

Explanation of symbols

20 Backlight 21 White LED
DESCRIPTION OF SYMBOLS 22 Lens 22a Optical-axis part of the lens surface 22b Side part of the lens surface 23 Point light source 24 Reflection sheet 25 Light-diffusion member 25a Illumination area 25b Boundary line

Claims (9)

A plurality of point light sources, and a light diffusion member that diffuses light from the point light sources,
The light diffusing member has a plurality of illumination areas formed corresponding to the plurality of point light sources,
When the angle between the line connecting the center of the point light source and the end of the illumination area corresponding to the point light source is θm with respect to the optical axis,
An illuminating device having a maximum value of radiation intensity in a direction of an angle θ satisfying an absolute value of 0 <θ ≦ θm. The lighting device according to claim 1.
The point light source includes a light emitting diode and a lens that changes a radiation intensity distribution of light emitted from the light emitting diode. The lighting device according to claim 2,
The illumination device according to claim 1, wherein a surface of the lens on the light emission side has a shape for changing a radiation intensity distribution of light emitted from the light emitting diode. The lighting device according to claim 3.
The illuminating device according to claim 1, wherein the lens has a shape in which a radius of curvature of the surface on the light emitting side increases toward the optical axis from a position at an angle of θm with respect to the optical axis. The lighting device according to claim 1.
An illuminating device comprising: a light shielding member disposed around the point light source. The lighting device according to claim 5.
The said light shielding member shields the light of the angle larger than (theta) m with respect to the said optical axis among the lights radiate | emitted from the said point light source. The lighting device according to claim 1.
The illumination device characterized in that light emitted from a point light source other than the point light source corresponding to each illumination region does not substantially enter the plurality of illumination regions of the light diffusion member. The lighting device according to claim 1.
The illumination device, wherein the plurality of point light sources are controlled in luminance of emitted light. A lighting device according to any one of claims 1 to 8,
A liquid crystal display device comprising: a liquid crystal panel disposed on a light emitting side of the illumination device.

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