JP2008004321A - Lighting device, electro-optical device, and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lighting device capable of deleting brightness unevenness. <P>SOLUTION: The lighting device, used, for instance, as a backlight for a liquid crystal display, is provided with a light guide plate, a light source, and a first craze film. The light source is arranged at an end face of the light guide plate to make light incident into the light guide plate. The first craze film is arranged on a face of either a light-irradiation face or a reflecting face of the light guide plate, with a plurality of crazes formed. This way, the lighting device can enhance dispersion of light irradiated from an irradiation face to delete brightness unevenness. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a lighting device used as a backlight of a display panel.

  In the liquid crystal display device, an illumination device is provided on the back side of the liquid crystal display panel in order to perform transmissive display. Light emitted from the illumination device passes through an optical sheet such as a diffusion sheet or a prism sheet, and then enters the liquid crystal display panel vertically. The liquid crystal display device displays the color display by transmitting the light emitted from the illuminating device to a color filter that transmits light of each wavelength of red, green, and blue stacked on the substrate of the liquid crystal display panel. Realized.

  An illuminating device includes a light guide plate and a light source provided on an end face of the light guide plate, and an LED (Light Emitting Diode) is often used as the light source. However, since the LED is a point light source, luminance unevenness occurs due to insufficient diffusibility of light, and there is a problem that the light emitting area of the light guide plate is reduced.

  The following Patent Document 1 describes a technique for manufacturing a visual field selective film having high visual field selectivity by utilizing regular directional crazing.

JP-A-11-231108

  This invention is made | formed in view of the above point, and makes it a subject to provide the illuminating device which can eliminate brightness nonuniformity.

  In one aspect of the present invention, the lighting device includes at least one of a light guide plate, a light source that is disposed on an end surface of the light guide plate and causes light to enter the light guide plate, and a light exit surface or a reflective surface of the light guide plate. And a first craze film in which a plurality of crazes are formed and disposed on either one of the surfaces.

  Said illuminating device is used, for example as a backlight of a liquid crystal display device, and is provided with a light-guide plate, a light source, and a 1st craze film. The light source is disposed on the end face of the light guide plate and makes light incident on the light guide plate. The first craze film is disposed on at least one of the light exit surface and the reflection surface of the light guide plate, and a plurality of crazes are formed. By doing in this way, said illuminating device can improve the scattering property of the light emitted from a light-emitting surface, and can eliminate brightness nonuniformity.

  In one aspect of the illumination device, the first craze film is disposed on both the light exit surface and the reflection surface of the light guide plate, and the light is laminated on the first craze film. A reflective sheet is further provided. Thereby, the scattering property of the light emitted from the light exit surface can be further enhanced.

  Another aspect of the above illumination device is a second craze film in which the light guide plate has a plurality of crazes substantially orthogonal to the plurality of crazes. That is, as a light guide plate of the illuminating device, a two-layer laminated craze film is used. By doing in this way, said illuminating device can aim at thickness reduction rather than using another member as a light-guide plate while expanding the emission direction of scattered light.

  As for the suitable one aspect | mode of said illuminating device, the said light guide plate has a predetermined pattern formed in the surface facing the surface in which the said several crazes are formed.

  In another aspect of the illumination device, the depth of the plurality of crazes is inclined at a predetermined inclination angle with respect to the light output surface of the light guide plate. Thereby, said illuminating device can emit more scattered light in the orthogonal | vertical direction with respect to the said light emission surface.

  In another aspect of the illumination device described above, the interval at which the plurality of crazes are formed differs depending on the location on the surface where the first craze film is disposed. By doing in this way, the brightness | luminance of the scattered light in said illuminating device can be varied with the place on the surface where the said 1st craze film is arrange | positioned.

  In another aspect of the present invention, the illumination device includes a light guide plate and a light source that is disposed on an end surface of the light guide plate and causes light to enter the light guide plate, and the light guide plate includes a plurality of crazes. Craze film.

  In still another aspect of the present invention, an electro-optical device including the above-described illumination device and a display panel illuminated by transmission of light emitted from the illumination device can be configured.

  In still another aspect of the invention, an electronic apparatus including the electro-optical device as a display unit can be configured.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the illumination device of the present invention is applied to a liquid crystal display device.

[First embodiment]
FIG. 1 is a cross-sectional view of a liquid crystal display device 100 according to the first embodiment of the present invention. The liquid crystal display device 100 mainly includes a lighting device 10 and a liquid crystal display panel 20. The illumination device 10 is mainly composed of a light guide plate 11 and a light source unit 15. The liquid crystal display panel 20 is disposed to face the upper surface side of the light guide plate 11. The light source part 15 is arrange | positioned at the end surface 11c of the light-guide plate 11, and is provided with several LED16 which is a point light source. The illumination device 10 includes a reflection sheet 14 on the lower surface side of the light guide plate 11.

  The light L emitted from each LED 16 enters the light guide plate 11 from the end surface 11 c of the light guide plate 11. In the light guide plate 11, the upper surface functions as a light output surface 11 a that emits light, and the lower surface functions as a reflective surface 11 b that reflects light. The light L changes direction by repeating reflection between the light exit surface 11a and the reflection surface 11b of the light guide plate 11, and exits from the light exit surface 11a to the outside. The emitted light L travels toward the liquid crystal display panel 20. Here, a craze film 17 is laminated on the light exit surface 11 a of the light guide plate 11. A plurality of crazes 17 a are formed on the craze film 17. As will be described in detail later, the light L is scattered by the plurality of crazes 17 a when passing through the craze film 17. The craze film 17 functions as the first craze film in the present invention.

  The liquid crystal display panel 20 has a display area substantially the same as the light emission area of the light guide plate 11. The liquid crystal display panel 20 is configured by bonding substrates 1 and 2 made of glass or the like through a sealing material 3 to form a cell structure and enclosing a liquid crystal 4 therein. The liquid crystal display panel 20 includes a polarizing plate 5 on the outer surfaces of the substrates 1 and 2.

  For example, a diffusion sheet 12 and a prism sheet 13 are provided as optical sheets between the illumination device 10 and the liquid crystal display panel 20. The diffusion sheet 12 has a role of diffusing the light L emitted from the light guide plate 11 in all directions. The prism sheet 13 has a role of condensing the light L on the liquid crystal display panel 20 and has a shape in which a prism shape having a substantially triangular cross section is extended in one side direction (direction of a side perpendicular to the cross section). . The light L emitted from the light guide plate 11 illuminates by passing through the optical sheet and then passing through the liquid crystal display panel 20.

  Next, the illumination device 10 according to the first embodiment will be described. Fig.2 (a) is sectional drawing of the illuminating device 10 which concerns on 1st Embodiment, FIG.2 (b) is a top view of the illuminating device 10 which concerns on 1st Embodiment.

  As shown in FIG. 2A, a craze film 17 in which a plurality of crazes 17 a are formed is laminated on the light exit surface 11 a of the light guide plate 11. The craze film 17 is made of, for example, plastic. “Crazy” as used in the present invention refers to a substantially linear crack or crack formed in a plastic film. In general, resin fibrils that remain between the walls of cracks or cracks formed on the plastic film are referred to as "crazes", and those that are spread and have no resin fibrils remaining are "cracks". In some cases, “craze” in the present invention includes both of them.

  As shown in FIG. 2B, in the illumination device 10 according to the first embodiment, the plurality of crazes 17 a are formed on the craze film 17 at a predetermined interval, and each craze 17 a is emitted from the light source unit 15. It is formed substantially perpendicular to the direction of the light L.

  FIG. 3 is an enlarged cross-sectional view of the illuminating device 10, and is an enlarged view of a portion surrounded by a wavy line 30 in FIG. 2A.

  Since the crazes 17a are cracks or cracks formed in the craze film 17 as described above, the crazes 17a become air layers. Therefore, a difference in refractive index occurs at the boundary between the portion of the craze film 17 where no craze 17a is formed and the craze 17a. Moreover, since the craze 17a is a crack or a crack, the shape of the wall surface of the craze 17a is irregular. Therefore, as shown in FIG. 3, the light reaching the boundary with the craze 17a out of the light L incident on the light guide plate 11 is scattered and reflected by the craze 17a in a direction substantially perpendicular to the craze 17a, and the scattered light Lr. As a result, light is emitted from the craze film 17. By doing in this way, the illuminating device 10 can improve the scattering property of the light emitted from the light emission surface 11a.

  As shown in FIG. 2B, since the light L emitted from the LED 16 serving as the point light source requires a certain distance to diffuse, the light L is not sufficiently diffused near the light source unit 15. Therefore, the area Ba between the adjacent lights L becomes dark, resulting in luminance unevenness. However, in the lighting device 10 according to the first embodiment, a part of the light L is scattered and reflected at the boundary with the craze 17a, and as shown in FIG. Since scattered light Lr is emitted from the craze film 17 in a direction opposite to the direction of the light L emitted from the light source unit 15, luminance unevenness that occurs near the light source unit 15 can be eliminated.

[Second Embodiment]
Next, a lighting device according to a second embodiment of the present invention will be described. FIG. 4A is a cross-sectional view of the lighting device 10 according to the second embodiment, and FIG. 4B is an enlarged cross-sectional view of the lighting device 10 according to the second embodiment. If it says, it is an enlarged view of the part enclosed by the wavy line 31. FIG.

  In the illuminating device 10 according to the second embodiment, unlike the illuminating device 10 according to the first embodiment, the craze film 18 is also laminated on the reflection surface 11b of the light guide plate 11.

  As shown in FIG. 4B, in the illuminating device 10 according to the second embodiment, the light reflected and returned by the reflection sheet 14 is scattered and reflected at the boundary with the craze 18a and guided as scattered light Lr2. It returns to the inside of the optical plate 11. As described above, the illuminating device 10 can also improve the scattering property of the light emitted from the light exit surface 11 a by the craze film 18 laminated on the reflection surface 11 b, and the luminance unevenness generated in a place near the light source unit 15. Can be eliminated. Accordingly, in FIG. 4A, the craze film is laminated on both the light exit surface 11a and the reflection surface 11b. However, the present invention is not limited to this. Instead, the craze film is only on the reflection surface 11b. It is good also as laminated. In the illuminating device 10 according to the second embodiment, the craze film is laminated on either the light exit surface 11a or the reflection surface 11b by laminating the craze film on both the light exit surface 11a and the reflection surface 11b. It is possible to further improve the light scattering property than to do.

[Third embodiment]
Next, the illuminating device which concerns on 3rd Embodiment of this invention is demonstrated. Fig.5 (a) is sectional drawing of the illuminating device 10 which concerns on 3rd Embodiment, FIG.5 (b) is a top view of the illuminating device 10 which concerns on 3rd Embodiment.

  In the illuminating device 10 according to the third embodiment of the present invention, unlike the illuminating device according to each of the above-described embodiments, the light guide plate itself is configured by laminating two craze films 17 and 19. This craze film 19 functions as a second craze film in the present invention.

  The craze 17a of the craze film 17 and the craze 19a of the craze film 19 are substantially orthogonal to each other. Thereby, as shown in FIG. 5B, the lighting device 10 has both the direction substantially perpendicular to the craze 17 a and the direction substantially perpendicular to the craze 19 a, in other words, the light L emitted from the light source unit 15. The scattered light Lr can be emitted not only in the direction but also in the direction perpendicular thereto, and the emission direction of the scattered light can be expanded. Moreover, the illuminating device 10 can achieve thickness reduction rather than using another member as a light-guide plate.

[Modification]
Next, a modified example of the present invention will be described. FIGS. 6A and 6B are cross-sectional views of the illumination device 10 according to the first modification. In the illuminating device 10 according to the first modification, the light guide plate 11 has a predetermined pattern formed on the surface facing the surface on which the craze film 17 is laminated. In the light guide plate 11 shown in FIG. 6 (a), an example in which a hemispherical pattern or a bowl-shaped pattern is formed on the reflective surface 11b is shown. In the light guide plate 11 shown in FIG. 6 (b), on the reflective surface 11b. As an example, a pattern having a triangular cross-sectional shape is formed as the predetermined pattern. The light L propagating through the light guide plate is reflected in such a predetermined pattern, so that the angle of incidence on the light exit surface 11a changes, so that it easily exceeds the critical angle with respect to the light exit surface 11a. Therefore, in the illuminating device 10 according to the first modified example, the amount of light emitted from the light exit surface 11a is increased and the luminance is improved as compared with a general illuminating device in which a predetermined pattern is not formed. By providing the craze film 17 on the light exit surface 11a, the light scattering property can also be enhanced.

  FIG. 7 is an enlarged cross-sectional view of the illumination device 10 according to the second modification. 2A is an enlarged view of a portion surrounded by a wavy line 30. FIG. In FIG. 3, the depth direction of the craze 17a is substantially perpendicular to the light exit surface 11a. However, in the illumination device 10 according to the second modification, instead, as shown in FIG. The depth direction is inclined at a predetermined inclination angle with respect to the light exit surface 11a. By doing so, the emission direction of the scattered light Lr can be directed in a direction perpendicular to the light exit surface 11a, that is, by the liquid crystal display panel 20.

  FIG. 8 is a plan view of the illumination device 10 according to the third modification. In each of the embodiments described above, in the lighting device 10, the plurality of crazes 17 a are formed on the craze film 17 at a predetermined interval. However, in the lighting device 10 according to the third modification, on the light exit surface 11 a. The interval between the crazes 17a formed is changed depending on the location, and the interval at which the crazes 17a are formed is varied depending on the position on the light exit surface 11a. Thereby, the brightness | luminance of the scattered light radiate | emitted from the light emission surface 11a changes with places on the light emission surface 11a. Specifically, the scattered light increases as the location on the light exit surface 11a where the interval at which the crazes 17a are formed is reduced, and decreases as the location on the light output surface 11a is increased at the interval where the crazes 17a are formed. That is, the brightness of the scattered light increases as the location on the light exit surface 11a where the interval between the formation of the crazes 17a is reduced, and decreases as the location on the exit surface 11a where the interval between the formations of the crazes 17a is increased.

  In a general lighting device, the farther away from the light source unit 15, the less light L emitted from the LED 16 reaches. Therefore, the luminance of light emitted from the light exit surface 11 a at a position away from the light source unit 15 also decreases. In the illuminating device 10 according to the third modified example, as shown in FIG. 8, the scattered light emitted from the light exit surface 11 a is reduced at a place away from the light source unit 15 by reducing the interval at which the crazes 17 a are formed. Increase the brightness of the scattered light. Thereby, in the illuminating device 10 which concerns on a 3rd modification, the fall of the brightness | luminance of the light emitted from the light emission surface 11a in the place away from the light source part 15 can be suppressed.

  Further, in each of the above-described embodiments, the craze 17a is formed so as to be substantially perpendicular to the light emission direction from the LED 16. However, the present invention is not limited to this. Instead, the craze 17a is Needless to say, the LED 16 may be formed at a predetermined angle with respect to the direction perpendicular to the light emission direction. Thereby, the emission direction of the scattered light in the light exit surface can be arbitrarily changed.

  In each of the above-described embodiments, the craze 17a is an air layer. However, the present invention is not limited to this. Instead, the craze 17a diffuses light such as a white color material. It may be filled with a diffusible material that can be used. Thereby, the illuminating device 10 can improve the light scattering property more. Alternatively, the craze 17a may be filled with an absorbing material that absorbs light. In this case, the illumination device 10 can emit light only in a specific direction. Further, when an absorptive substance that absorbs a specific wavelength is used as the absorptive substance, the spectral characteristics of light emitted from the light exit surface can be changed.

[Electronics]
Next, specific examples of electronic devices to which the liquid crystal display device 100 according to the present invention can be applied will be described with reference to FIG.

  First, an example in which the liquid crystal display device 100 according to the present invention is applied to a display unit of a portable personal computer (so-called notebook personal computer) will be described. FIG. 9A is a perspective view showing the configuration of this personal computer. As shown in the figure, a personal computer 710 includes a main body 712 having a keyboard 711 and a display 713 to which the liquid crystal display device 100 according to the present invention is applied.

  Next, an example in which the liquid crystal display device 100 according to the present invention is applied to a display unit of a mobile phone will be described. FIG. 9B is a perspective view showing the configuration of this mobile phone. As shown in the figure, the cellular phone 720 includes a plurality of operation buttons 721, a reception port 722, a transmission port 723, and a display unit 724 to which the liquid crystal display device 100 according to the present invention is applied.

  Electronic devices to which the liquid crystal display device 100 according to the present invention can be applied include a liquid crystal television and a viewfinder in addition to the personal computer shown in FIG. 9A and the mobile phone shown in FIG. Type / monitor direct-view type video tape recorder, car navigation device, pager, electronic notebook, calculator, word processor, workstation, videophone, POS terminal, digital still camera, etc.

It is sectional drawing which shows schematic structure of the liquid crystal display device which concerns on 1st Embodiment. It is sectional drawing and the top view of the illuminating device which concerns on 1st Embodiment. It is an expanded sectional view of the illuminating device which concerns on 1st Embodiment. It is sectional drawing of the illuminating device which concerns on 2nd Embodiment. It is sectional drawing and the top view of the illuminating device which concerns on 3rd Embodiment. It is sectional drawing of the illuminating device which concerns on a 1st modification. It is an expanded sectional view of the illuminating device which concerns on a 2nd modification. It is a top view of the illuminating device which concerns on a 3rd modification. It is the schematic which shows the electronic device to which the illuminating device of this invention is applied.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Illuminating device, 11 Light guide plate, 15 Light source part, 16 LED, 17 Craze film, 17a Craze, 20 Liquid crystal display panel, 100 Liquid crystal display device

Claims (9)

A light guide plate;
A light source that is disposed on an end surface of the light guide plate and causes light to enter the light guide plate;
An illuminating apparatus comprising: a first craze film on which at least one of a light exit surface and a reflective surface of the light guide plate is disposed and a plurality of crazes are formed. The first craze film is disposed on both the light exit surface and the reflective surface of the light guide plate,
The lighting device according to claim 1, further comprising a reflection sheet that is laminated on the first craze film and reflects light.   The lighting device according to claim 1, wherein the light guide plate is a second craze film having a plurality of crazes substantially orthogonal to the plurality of crazes.   The lighting device according to claim 1, wherein the light guide plate has a predetermined pattern formed on a surface facing the surface on which the plurality of crazes are formed.   5. The illumination device according to claim 1, wherein a depth direction of the plurality of crazes is inclined at a predetermined inclination angle with respect to a light exit surface of the light guide plate.   6. The lighting device according to claim 1, wherein an interval at which the plurality of crazes are formed varies depending on a place on a surface where the first craze film is disposed. A light guide plate;
A light source disposed on an end surface of the light guide plate, and causing light to enter the light guide plate,
The light guide plate is a craze film in which a plurality of crazes are formed. The lighting device according to any one of claims 1 to 7,
An electro-optical device comprising: a display panel that is illuminated when light emitted from the illumination device is transmitted.   An electronic apparatus comprising the electro-optical device according to claim 1 in a display unit.

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